Studies of thermal solution of Utah oil shale kerogen

Batch thermal solution of Hell's Hole Canyon oil shale in hydrocarbon solvents has been studied at temperatures of from 274° to 410°C. Three solvents were used: cyclohexane; 1,2,3,4-tetrahydronaph-thalene; and creosote oil. Five hundred mi 11iliters of solvent and 70 grams of -8 +28 mesh shale particles made up the charge to the 1-liter autoclave reactor. In 24-hour, constant-temperature runs under autogenous pressure, each solvent was found to be capable of removing over 90 percent of the original organic material at extraction temperatures of from 360°-375°C. Cyclohexane (in the supercritical state at all extraction temperatures) extraction resulted in somewhat greater yields than tetralin extraction in runs below 365°C but approximately the same yields as tetralin at higher extraction temperatures. With one oil shale sample, virtually identical yields (which were from 5 to 30 percent lower than those noted for all other samples at comparable temperatures) were observed in both cyclohexane and tetralin extractions. This finding suggests that mass-transfer restrictions within some oil shales may restrict the yield regardless of the solvent used. Carbon-13 nmr analyses of the spent shales showed that the aromaticity of the residual organic material in tetralin-extracted shale increased slightly from the raw shale value of 0.27 and remained essentially constant at a value of 0.31 as extraction temperature increased. Uniform removal of both aromatic and aliphatic organic carbon from the shale is thereby indicated. Pyrolytic processing, in contrast, removes only aliphatic carbons. In constant temperature runs of 24-hour duration, the aromaticity of an oil shale sample increased from the raw oil shale value of 0.17 to 0.28 after cyclohexane extraction at 326°C, while a tetralin-extracted sample of the same oil shale had an aromaticity of only 0.20 after extraction at 321°C. This finding suggests that tetralin is slightly more effective than cyclohexane at removing aromatic portions of kerogen. The nitrogen content of the cyclohexane extracts, which ranged from 1.58 to 2.24 percent, was comparable to that of values reported in the literature for shale oils. The tetralin extracts had somewhat lower nitrogen content, ranging from 0.58 to 1.95 percent. Extract nitrogen content generally increased with extraction temperature. Simulated distillation by gas chromatography shows that the boiling range of the extracts shifted to lower temperatures as extraction temperature increased. An exception was observed for a very rich oil shale, for which a maximum in production of low-boilers with cyclohexane was observed at an extraction temperature of 365°C; either lower or higher extraction temperatures produced a higher boiling extract. Cyclohexane extracts were generally lower boiling and of wider boiling range than tetralin extracts: 48.5% of a 320°C cyclohexane extract of a 17 gal/ton shale boiled below 375°C and 19.8% boiled between 375° and 425°C; for a 326°C tetralin extract of the same shale, the corresponding numbers were 23.2% and 54.8%. Liquid-phase extraction with tetralin may therefore be considered to be a more gentle process in that less alteration of the original organic structure occurs. Kinetic parameters for tetralin extraction were determined by integral, differential, and difference-differential analysis of yield data taken by exposing the sample charge to a temperature ramp (0.2°C/min) then quenching after the desired maximum temperature had been reached. A competitive first-order reaction mechanism for the formation of the soluble bitumen was suggested by the results of each of the analyses: Kerogen --------> Bitumen T<350°C Bitumen T>35O°C. No evidence was found to indicate a difference between the low and high temperature reaction products, the proposed mechanism merely states that two parallel pathways for bitumen formation exist. Mathematically fitting the conversion data to this model resulted in the calculation of the following Arrhenius activation energies and pre-exponential factors: Ai = 2.2 x lOVmin T < 350°C Ej = 20.8 kcal/mole A2 = 1.7 x 1013/min T > 350°C . E2 = 45.7 kcal/mole Good agreement with literature values for low-temperature kerogen conversion was noted.

STUD IES OF THERMAL SOLUTIDN OF UTAH OIL SHALE KEROGEN by Armand Scott Kafesjian A dissertation submitted to the facult.y of The University of Utah in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemical Engineering The University of Utah December 1983 Copyright c Scott Kafesjian 1983 All Rights Reserved • THE Ul\:IVER ITY OF TAH GRADUATE SCHOOL SUPERVISORY CO�1MITTEE APPROVAL of a dis ertalion submitted by Armand Scott Kafesjian Thi di senation has been read b maj orit . Vale has been found to . each member of the follo ..... ing supervisory committee and by be satisfactory. 4-- Alva D. Baer THE UNIVERSITY OF UTAH GRADUATE SCHOOL FINAL READING APPROVAL To (he Graduate Council of The University of Utah: A. Scott Kafesj; an in its I have read the dissert4tion of final form and have found that (I) it formal. citations. and bibliographic style are consistent and acceptable; (2) its illustrative materials including figures. tables. and charts are in place; and (3) the final manuscript is satisfactory 10 the Supervis­ ory Commiuee and is ready for submission to the Graduate School. � ale ff, . 31, 1983 g ust .3�/'7d3 A. Lamont Tyler Chairperson. Supervisor' Commillee Approved for the Major Dep art men t Approved for the Graduate Council ABSTRACT Batch thermal solution of Hell's Hole Canyon oil shale in hydrocarbon solvents has been studied at temperatures of from 274 0 to 410°C. Three solvents were used: cyclohexane; 1.2,3,4 -tetrahydron aph- thalene; and creosote oil. Five hundred mi lliliters of solvent and 70 grams of - 8 +28 mesh sha le particles made up the charge t o the I-liter autoclave reactor. In 24 -h ou r. constant -temperature runs under autogenous pressure, ea ch solvent was found to be capable of r emoving over 90 percent of the original temperatures of from 360°_375°C. organic material at extraction Cyclohexane (in the 5upercritical state at all extraction temperatures) extraction resulted in somewhat greater yields than tetral;n extraction in runs below 365°C but approximately the temperatures. With one oil shale sample, vi rtually identical yields same yields . as tetralin at higher extraction (which were from 5 to 30 percent lower than those noted for all other samples at comparable temperatures) were observed in both cyclohexane and tetralin extractions. This f inding suggests that mass-transfer restrictions within some oil shales may restrict the yield regardless of the solvent used. Carbon-I3 nmr analyses of the spent shales showed that the aromaticity of the residual organic material in tetralin-extracted shale increased slightly from the raw shale value of 0.27 and remained essentially constant at a value of 0.31 as extraction temperature increased. Uniform removal of both aromatic and al iphatic organi c carbon from the shale is thereby indicated. Pyrolytic procesSing, in contrast, removes only aliphatic carbons. In constant temperature runs of 24 -hour duration, the aromatic1ty of an oil shale sample increased from the raw oil shale value of 0.17 to 0.28 afte r cyclohexane extraction at 326°C, while a tetralin-e xt racted sample of the same oil shale had an aromaticity of only 0.20 after extraction at 321°C. This finding suggests that tetral;n is slightly more cyclohexane effective than at removing aromat ic portions of k.erogen. The nitrogen content of the cyclohexane extracts, which ranged from 1.58 to 2.24 percent, was comparable to that of values reported in the literature for shale oils. The tetralin extracts had somewhat lower nitrogen content, ranging from 0.58 to 1.95 percent. Extract nitrogen content general ly increased with extraction temperature. Simulated distillation by gas chromatography shows that the boiling range of the extracts shifted to temperature increased. An exception was observed for a very rich oil '. lower temperat ures as extraction shale, for which a maximum in pr oduction of low-boilers with cyclohexane was observed at an extraction temperature of 365·C; either lower or higher extraction temperatures produced a higher boiling extract. Cyclohexane extracts were generally lower boiling and of wider boili ng range than tetral;n extracts: 48 .5% of a 320·C cyclohexane extract of a 17 gal/ton shale boiled below 375'C and 19.8% boiled between 375' and 425·C; for a 326·C tetral;n extract of the same shale. the corresponding nUmbers were 23.2% and 54.8%. therefore be Liquid-phase ext raction with tetral;n may considered to be a more gentle process alteration of the original organic structure occurs. v in that less Kinetic parameters f or tetralin extraction were determined by integr al, differential. and difference -different i al analysis of yield data taken by exposing the sample charge to a temperature ramp (O . 2-e/ min) then quenchi ng after the desired maximum temperature had A compet it ; ve fi rs t -order reacti on mechani sm for the been reached . f ormation of the soluble bi tumen was suggested by the resu l ts of each of the anal yses : Keroge n I > Bitumen T<350oC ~ Bitumen T>3 50oC . No ev idence was found to indicate a differenc e between the low and high t emperature reaction products, the proposed mechanism mere ly states that two para l lel .. Mathematically pathways for bitume n f ormation exist. fit ti ng the conversion dat a t~ this mode l resulted in the ca lcul ation of the fol lowing Arrhenius acti vati on energies and pre-exponential factors: A) = 2. 2 x 10'/min T < 3500C E) = 20.8 kcal/mo l e A, = 1.7 x 10l3/ min T > 3500C • E, = 45.7 kcal/mo l e Good agreement with li terature values conversion was noted . vi f or low-tempera t ure kerogen To my parents, with gratitude fo r the support and encouragement which they have provided me. CONTENTS ABSTRACT • •• • iv • • • • x • • • • • xii • LI ST OF TAB LES • LIST OF FIGURES. • • • • • • LI ST OF SYMBO LS. xvi • ACKNOWLEDGEMENTS xix · 1. I NT RODUCTl ON 2. PREVlOUS WORK . • 2.1 ·· 2.2 3. 4. • • • • • • • 13 14 17 21 22 29 • • 32 • • · ··• ·• 1 13 Sol ubi l i t y Stud; es. • • • • • • 2.1.1 Therma l Solution • 2. 1.2 Ext ra ct Character . • K~netic Studi es • • • • 2. 2 .1 Meehan; sm of Kerogen Decomposition • 2.2.2 Thermal So l ufion Kinetics. • • • ·• ····· • • • • 3.1 Expe rimenta l Plan • • • · · ·and· ·Procedure · · · · ·. 3 . 2 Experimental Appa ratus • 3. 3 Ana l ytical Methods. • • • • · • · · · ·• ·• 3.3.1 Elementa l Analysis • • ··• · 3.3.2 Simu la ted Di st i llat ion 3.3.3 Carbon-13 Nuclea r Magnetic Reson ance • RESU LT S. . • • ··.··• ·• • ···· 4.1 Yield St ud; es • · ·Sol· vent/Shale · · · · · ·Ratio. ·• • 4. 1.1 Effe ct of • 4. 1. 2 Effect of Particle Size . · ·Organ · • i c Content. 4.1.3 Effect of Sol vent and Sha le EXPE RIME NTAl 4.2 • • • • • • Spe nt Sha l e Organic Resid ue Analysis. 4.2 .1 Elementa l Analysis • • 4. 2. 2 Carbon-13 nmr with CP/MAS. • ·· ··· • • • • 32 37 50 50 54 61 • • • 67 • 67 69 71 71 85 85 96 • • • • • • • • ··· • < 4. 3 Extract Analysis . ··..·· • lOB 4.3 .1 Simulated Distil l ation • 4.3.2 El emental Analysis • • • • 4. 4 Kinetic Study • • • • • • • • • • • 4.4. 1 Theoretical Deve l opment of Kinetic Ana l yses . • • 4.4 . 2 Kinetic Model . ···· l OB 12B 141 143 157 • • • • 167 • • ··.. 5. CONCLUSIONS . .....·· 5.1 Suggestions for Further Work. • • • • • • 170 Appendices A. MASS BALANCE - - CALCULATION OF YlELO • •• •• • 172 B. GC SIMULATED DISTILLATION DATA REDUCTION PROGRAM "SlMDlsr ". . •• . •• ••• •• •• ••• C. 173 • • • • RAW DATA FROM THERMAL SOLUTION EXPERIMENTS IB7 D. ELEMENTAL ANALYSIS DATA • • •• • • • • 194 E. GC SIMULATED DISTILLATION DATA 201 r. FUNCTION MINIMIZATION PROGRAM -- "FUNMIN" . 204 REFERENCES VITA •• • • • • • · • • • • 1x •• • • • • • • • • • • • • • 214 222 LIST OF TABLE S , 1. 1 Proposed Elemental Formulae and Molecular Weights for Kerogen (After Alston, 1978) . 6 1.2 Products of Kerogen Pyrolysis (After Al l red, 1967). 8 3.1 Analys is of the Five He ll' s Hole Canyon Oil Sha l e Samples Used in this Wo rk . . . . . . . . . . . 41 3.2 American Wood Preserver 's Association Standard PI-78 (Revised) -- Standard Specifications for Creosote 0; 1. . . . . . . . . . . . . . . 51 Composition of the n- Paraff in CaliDration Standard with Normal Bo; 1; ng Po; nts and Typical Retention Times of Components 56 Operating Parameters for GC Simu lat ed Di st ill at ; on . . . . . . . . . . . . . 60 3.3 3.4 3.5 Instrument Conditions used in Carbon -I 3 nmr with CP / MAS . •• 4.1 -. 66 Results of Carbon -I3 nmr Analysis of Spent Shales from Linear-Heating Runs 105 C.l Raw Data from Cyclohexane Runs . . 188 C.2 Raw Data from Const an t-Temperature Tetral,n Runs. 189 C.3 Raw Oat a from Creosote 0; 1 Run s . . . 190 C.4 Raw Data from Tetralin Linear-Heating Runs. 191 C.5 Raw Data from Variable Solvent /S hale Ratio Runs 192 C.6 Raw Data from Variable Particle Size Runs 193 0. 1 Elemental Analys i s Resu lt s: Residues of Cyclohexane Extractions . . . . . . . 195 El emental Analysis Results: Residues of ConstantTemperature Tetral;n Extractions . . . 196 0.2 ,. 0.3 Elementa l Analysis Results: Residues of LinearHeating Tetra';n Extractions . . . 197 0.4 Elemental Analysis of Cyclohexane Extracts. 198 0.5 Elemental Ana lysis of Constant-Temperature Tetral in Extracts . . 0.6 Ll L2 . 199 Elemental Ana l ysis of Linear-Heating Tetral,n Extracts. • •. 200 Simulated Distillation Re sults for Cyclohexane Extract.), • • • 202 Simulated Distillation Results for ConstantTempe rature Tetral;n Extracts . . . . . . . . . • . • 203 ". xi LIST OF FIGURES 1. 1 1.2 Ma p Showin9 location of Oil Shale Deposits of The Green River Formation (after McCa rthy . 1976) ·... 3 Schematic of a Vertica l In - Situ Retort. McCarthy and Cha (1976). Reprinted from Colorado School of Mines Quarterly. Vol. 71, No.4, by permis sion . • . • • • . . • • • • • . • • • . • • • 10 2 .1 Overview of Proposed Kerogen Decomposition Schemes • 23 3.1 Schematic Diagram of Furnace and Vessel Interior Tempe rature Traces for a Constant-Temperature Run Illustrating the 2-to-3 hour Induction Period and 34 the Rapid Cool - Down at the End of the Run • • •• 3.2 Schematic Diagram of Furnace and Vessel Interior Temperature Traces for a linear-Heat i ng Run. the Rate of Temp erature Increase of the Interior 3.3 Becomes Constant at About 150°C •. • . • • ·... 36 Schematic O~a9ram of the l - liter Autoclave Used i n Batch Thermal Solution Runs Illustrating its Major Components • • • . • • • . . . • • • • • ·... 38 .... . 43 3.4 Schematic Di agram ....Showing Apparatus and Wiring for Constant-Temperature Runs . • . • • . • • . 3.5 Schematic Diag ram Showing Apparatus and Wiring for linear - Heati ng Runs . • . . . •• •. . .• 3.6 Schematic Diagram of Tube Fu rnace Used to Oxidize Organic Residue from Spent Sha l es . 45 .... 3.7 Ca l ibration Curve for GC Simulated Distillation •• 3. 8 Ill ustrat io n of Calculation of Resolution for n-C 18 and n-C 16 Hydrocarbons Under Simulated Di stil l ation Operating Conditions . •• • • • . 3.9a Insta nt ane~~s a pair of Dipole -Dipole Interaction Between C and H Nuclea r Magnetic Moments • • • • • • • • 48 57 58 63 3.9b Ihe Effect on a Particular Pair of l3C and H Nuclei of Rapid Spinning of the Sample Containing them about an axis oriented at the Magic Angle Relative to the Static Ma~netic Field, Hot Showing the Instantaneous (r) and Average lr av ) Internuclear Vectors. (After 8artuska et al., 1977) . . . . . . . . . . • 63 4.1 Yield vs. Solvent/Shale Ratio in Tetralin, 350' t 3'C. 70 4.2 Yield vs. Temperature in Cyclohexane 72 4.3 Yield vs. Temperature in Tetral;n . . 75 4.4 Yield vs. Temperature for Rich Grade Shales in Cyclohexane (Shale C) and Tetralin (Shale 0). 76 4.5 Yield vs. Temperature for Lean Grade Shale (Shale A) in Cyclohexane and Tetralin. 77 4.6 Yield vs. Temperature for Medium Grade Shale (Shale B) in Cyclohexane and Tetralin . . . . 81 4.7 Yield vs. Temperature in Creosote Oil (Shale 0). 83 4.8 Hydrogen-to-Carbon Atomic Ratios of Residual Organic Material. Solvent: Cyclohexane . . . 87 Nitrogen-to-Carbon Atomic Ratios of Residual Organic Material. Solvent: Cyclohexane . . . 88 Hydrogen-to-Carbon Atomic Ratio of Residual Organic Material. Solvent: Tetralin . . . . 90 HYdrogen-to-Carbon Atomic Ratios of Residual Organic Material from linear-Heating Runs. Solvent: Tetralin . . . . . . . . . . . . . 91 Nitrogen-to-Carbon Atomic Ratios of Residual Organic Material. Solvent: Tetralin . . . . 94 Nitrogen-to-Carbon Atomic Ratios of Residual Organic Material from linear-Heating Runs. Solvent: Tetral;n . . . . . . . . . . . . 95 Plot of Aromatic Carbon in Spent Shale vs. Aromat ic Carbon in Raw Shale for Different Oi 1 Shales, Miknis et al., 1982 . Adapted from Fuel, vol. 61. . . . . . . . . . . . . . . . . 98 4.9 4.10 4.11 4.12 4.13 4.14 xi i i 4.15 4.16 Plot of Aromatic Carbon vs. Retorting Temperature for a 30 gal/ton Colorado Shale, MiKnis et a1., 1982. Adapted from Fuel, vol. 61 . . . . . . . . . . . . . . -.-.-. . . 98 Carbon-13 nmr Spectra of a 55 gal/ton Colorado Shale Heated t o the Indicated Retorting Temperatures for 24 Hours, Miknis and Maciel, 1981. Reprinted from Proceedings of the 14th Oil Shale Symposium. by permission. . . . . . . ....... . 99 4.17 Carbon-13 nmr Spectra of a 54 gal/ton Hell's Hole Canyon Oil Shale . . . . 101 4.18 Carbon-13 nmr Spectra of 35 gal / ton Hell's Hole Canyon 0; 1 Sha l e . . . . 102 4. 19 Carbon-13 nmr Spectra of 43 gal/ton Hell's Hole Canyon Oil Shale used in linear-Heating Runs 104 4.20 Chromatogram of Typical Cyclohexane Extract . . . 110 4.21 Distillation Curve for Typical Cyclohexane Extract 112 4. 22 Chromatogram of typical Fischer Assay Shale Oil . . 113 4.23 Distillation Curve for Typical Fischer Assay Shale Oil 114 4.24 4.25 Variation of Boiling Point Distribution for Cyclohexane Extracts of Shale A (17 gal/ton) with Extraction Temperat~re . . . . . . . . . .• Variation of Boiling Point Distribution f or Cyclohexane Extracts of Shale 8 (35 gal/ton) with Extracti on Temperature . . . . . . . . . 4.26 115 116 Variation of Boiling Point Distribution for Cyclohexane Extracts of Shale C (62 gal/ton) with Ext raction Temperature . . . . . . . 117 4.27 Chromatogram of Typical Tetralin Extract . . 120 4.28 Distillation Curve of Typical Tetralin Extract 121 4.29 Variation of Boiling Point Distribution for Tetral;n Ext racts of Shale A (17 gal/ton) wi th Ext ract i on Temperature. . . . . . . . . 4.30 122 Variation of Boi1;ng Point Distribution for Tetral;n Extracts of Shale B (35 gal/ton) with Extraction Temperature . . . . . . . . . xiv 123 4 . 31 Variation of Boiling Point Distribution for Tetra1 i n Extracts of Shale 0 (54 9a1/ton) w~th Ext ract ion Tempe rature . . . . . . . ... 124 4.32 Hyd rogen -ta-Carbon Ratios of Cyclohexane Extracts. 129 4.33 Ni t ra ge n-to - Carbon Atomic Ratios of Cyc l ohexane Extracts . . . . 131 4.34 NH ragen Content of eye 1ohexa ne Extracts . . 4.35 Hydrogen-ta-Carbon Atomic Ratios of Tetralin Extracts, Constant -Temperature Runs • • . . 4.36 Hydrogen-ta-Carbon Atomic Ratios of Tetralin Extracts, . . . .. . ..... 133 • 134 ·... ....... 135 4.37 Nitrogen-ta-Carbon Atomic Rat; 05 of Tetra l in Extracts, Constant -Tempe ratu re Runs. • • • 137 4.38 .... ·.. Nitrogen Content of Tetra11n Extracts, Constant Temperatu re Runs . . . . . . . . . . . . . . . . . . . Nitrogen Content of Tetralin Ext racts, Li near......... Heating Runs . • . . . . linear-Heat i ng Runs •• • • • • • ·. ......... Nitrogen-ta-Carbon Atomic Ratios of Tetralin Ext ra cts , Linear-Heat ing Runs • •• • • • • 4.39 4.40 4.41 rate 4.42 = O.2°C /mi n. Sol vent: Heatin9 Inte gral Analysis (Coats and Redfern Method) of 149 Different i a 1 Analysi s (A rrheni us Plot) of LinearHeating Yie l d Oata •• • • • • • 4 .44 ·........• • • 152 • 156 Difference-Differentia l Ana l ysis (Freeman-Carroll Method) of Linear-Heatin9 Yield Data • • • • • • • 4.45 140 144 Tetralin . • . • Linear-Heat i ng Yield Data . • • . . • • • • • • . 4.43 139 Yield vs . Temperature in Linear -Heating Runs, 42 9a1 / ton Hen:s Hole Canyon Oil Shale . < 138 Conversion Calculated from Kinetic Model (Equation 4 . 24) Compared with Experimental Data from Linear-Heating Runs • • • • • • • 4.46 • 163 Plot of Reaction Rate Constants. "1 and "2' vs. Tempe rature. • • • • • • • • • • • . . • • • • • • • 165 xv LI ST OF SYMBOL S min- 1 A Pre-exponential factor Al Pre-exponential factor for react ion I, min- 1 A2 Pre-exponentia l factor for react ion 2, min -1 b Durrmy variable in Equation 4.9 d Differentia l operator E Activation energy, kca l /mo le Eo Energy of interaction of two magnetic dipol es, kcal E1 Activation energy for react ion I, kcal/mole E2 Act i vation energy for reaction 2. kcal /mo le f Funct iona l dependence of reaction rate on conversion fa Aromatic1ty fr Weight fraction of organic Imterial in raw shale fs Wei ght fraction of organic material in spent sha le Ho Externa 1 magnetic field vector k Reaction rate constant, mi n- I kl Reaction rate constant for reacti on I, min- I k2 Reaction rate constant for reaction 2, mi n- I m Durnny var; able in Equation 4.9 n Reaction order P R 9 -. Series approximation of te rms in brackets in Equation 4 .. 23, given by Equation 4 . 25 . Gas constant, 1.987 x 10- 3 kcal/mole - K Resolution, defined by Equation 3.1 r Internu cl ear distance, em Average internuclear distance for spinning sample , em S Least squares residual T Absolute temperature. K Tj jth maximum run temperature. linear-heat ing runs. °C Tmax Maximum temperature reached in linear-h eating run, °C Hypothet i ca 1 mi ni mum temperature at wh1 ch kerogen decomposit 1on rate becomes measureable. K t Time, min. tl6 Elution time of n-hexadecane times chart speed, mm tIS Elution time for n-octadecane times chart speed , mm u EIRT, durrmy variable Woe Wei ght of organ i c material re moved from shale, g Wr Weight of raw shale, g Ws Wei ght of spent sha 1e. g w16 Width of n-hexadecane peak, mm WIS· W~ x Fractional convers i on of kerogen dth of n-octadecane peak, mm Fractional conversion of ke ro gen at Tj calculated from Equation 4.24 Yj Fractional yield heat; ng runs (experimental) z; E;/RT, dummy variable zl EI/RT, du~ variable Z2 E2/RT, dummy variable xvi i at jth temperature in l i near- Greek letters B Heating rate, °C/m1n A Difference operator e Angle between external magnetic internuclear vector. radians em Magic angle . 0.955 radians (54.74°) lJ.C Ma gneti c IT()ment of carbon atom. kcal /gauss lJ.H Magnetic roment of hydrogen atom, kcal/gauss " xviii field and carbon -hydrogen ACKNOWLEDGEMENTS This work would not have been possible without the assistance of a number of people and organizations. author wishes Company. to thank For the i r f i nancial support. the the Department of Energy and Equity Oil Appreciation is expressed to Dr. Kurt W. Zilm, Dr. Ronald J. Pugmire, and Dr. Charles L. Mayne for their ass istance in obtaining the nmr spectra and aiding i n their interpretation. The cooperation of Dr. Francis P. Mik nis in obtaining samples of Antrim 011 appreciated. shale is also Than ks are also extended to Ray Cayais for his timely assistance in the machine shop. Finally. sincerest grat it ude is expressed to Or. A. La mont Tyler whose fr iendship , encou ragement, and guidance throughout the duration of this endeavor have been indispensible . CHAPTER I INTROOUCTION Historically. interest in commercial development of the oil shale reserves of the United States has followed a cyclical pattern. D1 scovery of pet ro 1eum at Ii tus vi 11 e, Pennsy han; a in 1859 rna rked the decline of the early oil shale industry in the eastern United States. which was geared toward manufacture of kerosene from crude shale 011. A resurgence of interest in oil shale resources took place 1n the 19205. stimulated by increased demand for gasoline to fuel number of automobiles on the road. the ever - growing A mini - boom in the area of the Green River Formation resulted in the formation of over 200 companies and the filing of thousands of mining claims (Sladek, 1974) on the rich oil shale beds underlying parts of Utah, Colorado, and Wyoming . discovery of large oil . Subsequent reserves in east Texas brought an end to this land rush. The next period of revived interest in 011 shale development was brought about Synthetic near the end of World War II Liquid Fuels Act which was by the passage of the aimed at development of alternative, domestic sources of liquid fuels. Research carried out during this of a nurTtler of new period resulted in the development retorting technologies, and seemed to be proceeding toward large-scale production of shale oil until the discovery of the extensive petroleum reserves in the Mi ddle East. 2 Increased reliance on imported crude oil in the following decades stirred little concern regarding the lack of energy independence of this country until the events of the early and mid-1970s illustrated the consequences volatile excess i ve of regio ns. pet ro 1eum i mportat i on from pol i t i ca 1'y Together with projected increases in demand for liquid-fuels, actions directed toward rapid corrmercial development of the oil shale reserves of the Green River Formation were stimulated by the sudden shortage of crude oil. Recently. the unanticipated decrease in energy consumption has resulted in an excess of crude 011 in the world market and has caused a number of would-be shale-oil producers to critically re-evaluate their synfuel projects. Many of these projects have been i ndefi nitely suspended at the present time; several smallerscale developments are proceeding, however, and production is scheduled to begin late in 1983. Survival of those continuing projects has been a result of g\larant1es to purchase the produced shale-oil and financial assistance from government ...· organizations, thereby lowering the risk. involved in produci ng a product which is to compete in a constantly fluctuatin9 mark.et. Some 14,000 square miles of Utah, Colorado, and Wyoming are underlain by oil shale beds in four basins (Sladek, 1974), constitutin9 the Green R~ver Formation, illustrated in Fig. 1.1. Estimates of the magnitude of the in-place reserves contained in the formation a're on the order of two trillion barrels of 011 equivalent (Dineen and Cook, 1972; Duncan and Swanson. 1965), approximately three times the proven world petroleum reseryes (World Oil, 1977). 3 I 6REEH RIVER -----10 IDAHO ' BASIN (~~~;t ~ 0 SPRING ROCk WAS HAk iE I ASI N I WYO~IJ:!i.__ "":::-""_ _<" IITA. COt..ORADO UI HTA BASIN PI CEANCE BASIN o CAN YO N 6RAKD JUNCTION o 25 75 50 100 Pl I LES D KNOWN DEPOS ITS AREA OF 25 GALLONS 'ER TON OR 6REATEJt Figure 1.1 Map Showing Locati on of Oil Shale Depos its of the Green River Format i on (after McCarthy, 1976) • 4 The 0; 1 sha 1e of the Green River Format i on or i 9 i nated in the Eocene epoch of the Tert ; ary per i ad approx imate 1y 35 to 55 m; 11 i on years ago. During that time, two large fresh-water lakes covered extensive areas of southwestern Wyoming. northeastern Utah, and northwestern Colorado. Simultaneous dep osition of mineral and algal material on the beds of these 1 akes resu lted ; n the accumu 1at i on of th; ck 1ayers of sed; ment s. Climatic changes and gradual uplift of the entire region resulted in di sappearance of the 1akes. Subsequent compact; on of the sediments and action of other geological processes left behind the oil-shale beds and resulted in the presently observed topography of high, steep-sided plateaus cut by streams to produce narrow valleys and canyons. Oil shale beds as thick as 1,500 to 2,000 feet have been identified in some areas of the Piceance Bas;n of northwestern Colorado. The term "all shale" is a misnomer since the parent rock is not a shale and there ;s no oil contained in the material. Green River oil shale ;s best described as a lamellate, fine-grained sedimentary rock ". composed of an intimate mixture of organic and inorganic constituents. Strong bonds, the exact nature of which ;s not completely understood, exist between the organic and inorganic portions, making complete separation of the two portions difficult to accomplish. complete isolation of unaltered organic material has In fact, not been accomplished to date. A typical 25-gallon-per-ton Green River shale consists · of 86.2% inorganic and 13.8% organic material (USBM, 1960). Fifty percent of the inorganic portion consists of dolomite, (CaMg (C0 3 )2) and calcite (CaC0 3 ) (USBM, 1960). which are the primary mineral constituents of Green River 5 oil shale. lesser amou nts of silicates, sulfides, other carbonates, and numerous trace m~nerals portion cons ist s hi ghly are also present (Jaffe. 1962) . prima rily of a materi al cross -l i nked, called kerogen, hi gh-molecular-weight insoluble in conrnon solvents. The organic a complex, macromolecule which 1s Heteroatoms of nitrogen, sulfur, and oxyge n are present in kerogen as are carbon and hydrogen. Typical elemental composi tions and molecular formulae for the organic portion of Green River shale are listed in Table 1.1. In addition to kerogen, mi nor amounts of nat urally occurring soluble material (generally less than 10% of t otal organic), known as natural bitumen, are present in Green River 011 shale. A1thou gh the exact st ructu re of keroge n 1sunk nown, character1 zati on of ke rogen by x-ray diff r act i on (Yen, 1974) and micro-pyrochromato( $chm~ graphy and mass spect romet ry dt -Co11 erus and Pri en, 1976 ) has shown that Green River kerogen consists of a variety of single-and multi-ring structures (tetrali.[ls, isoprenoids, terpen oids , steroids, and carotenoi ds) interconnected by alkanes disulfide, ethe r, and ester linkages. and isoprenoids as well as In rich 011 shale, the kerogen may be thought of as being essentially a continuous phase, throughout wh ic h the mineral constituents are dispersed. After removing all the organic mate rial, the rema i ni ng mineral residue has very little strength and is quite friable. Recovery of crude shale oi l is cOrTmon ly achieved by destructive distl11ation (pyrolysis) of kerogen at high temperatu res (400'-SOO'C); 011 is then collected as the condensate of evolved organic vapors. Shale 011 i s a premium-quality material similar t o petroleum, although 6 Table 1.1 Proposed Elemental Formulae and Molecular Weights for Kerogen (After Alston, 1978) Formula Molecular Composition H C 0 S N Wei ght Reference 206.68 315.07 5.26 1.00 11.08 3083.6 Smith (1961) 215 330 5 1 12 3209.2 Hei stand and Humphries (1976) 150 {6 ) 246.5 (9.86) 4.5 ( .1 8) 1 (.04 ) 14 ( • 56) 2369.2 Stanfield et al. (1951) 200 300 5 1 11 2982.7 Weitcamp and Gutberlet (1970) 3000 Jones and Dickert (1965) < 7 generally higher in nitrogen and sulfur than most crudes. At temperatures above about 400°C. the organic material begins to thermally decompose to recoverable l i quid and gaseous products as well as solid carbonaceous residue which remains on the shale. Some retorts are des 1 gned 1n such a way that thi 5 res i due 15 bu rned to prov; de heat for the thermal decomposition. Typical product y i elds from pyrolysis of Green River 011 shale at 490°C are shown in Table 1.2. Other rrethods such as biochemical lea ching (Meyer and Yen, 1974), and hydrogenation (Schlinger and Jesse, 1967), exploratory re covery schemes. have been employed as small-scale, Other physical and chemical techniques for separation of organic and inorganic matter have been studied, primarily analysis as methods of concentrating kerogen rather than as a recovery technique for further detailed (for example SmHh and Higby, 1960; Hubbard et al., 1952; Thomas and lorenz, 1970). Retorting I.. categori es: technologies may be '. above-ground and i n-s itu . placed in one of two broad Above-ground retorting processes require mining of large quantities of shale. subsequent size reduction and solids-handling processes, retort i ng 1n one of the variety of vessels which have been developed. recovery of the desired products, and, finally. spent sha le disposal. The Paraho, Tosco II, Union A and B, and methods. Petrosh tec.hnologies are repre sentative of the above-ground In-sHu retorting involves in-place generation of recoverable hydrocarbons from the shale. Partial TTrlning of a deposit followed by explosive rubbleization of the remaining shale into the mined-out space constitutes the "modHi ed in -s itu" method. Mi ned sha 1e may then be retorted 1n an above-ground vessel to realize fullest utlilization of 8 Table 1.2 Products of Kerogen Pyrolysis (After Allred, 1967) Percent Conversion of Organic to Oil Gas + Water + Loss Residue Reference 54.3 24.3 21. 5 Smith (1962)a 56.9 21. 2 22.0 Goodfellow et al . (1968)b 61.4 15.9 22.8 Stanfield et a1. (1951)C 61 17 22 Allred (1976)d 62.4 20.5 17.1 this work e a. b. c. d. e. Data from 8 replicate samp l es, 25.2 gal/ton Data from 42 re pli cate samples, 33.2 gal/ton Average of 9 sample~ , 18-52 gal/ton Data cove r multiple ·s amples. 5-93 gal/ton Average of 7 samples, 42-64 gal/ton 9 the resource. The Occidental process is an example of this technology (McCarthy et a1., 1976). "True!! in-situ r etorting methods require no mining; the void space or porosity req uired for adequate mass transer and fluid flow in the bed must be created by some other means. of true in - situ technologies are: Examples the Geokinet;cs horizontal in-situ process wh i ch re 1; es on carefu lly timed detonat; on of exp los i yes to fracture the shale and create void space in the bed (Lekas, 1981), the Equity Oil "BXII process designed to take advantage of voids created by remoyal of minerals by groundwater percolation in the so - called "leached zone" of the Piceance Basin of Colorado (Dougan and Dockter, 1981), and the U.S. Bureau of Mines combination space. of hydraulic exper i menta l fracturing in·situ retort and explosives which uses to create a void Heat may be supp 1i ed to an i n·s i tu retort by inject i on of hot air or superheated steam, or by cont r olled combustion of residual carbon on the shale; in the latter case, the rate of air injection into the bed controls the combustion rate. - An idealized vertical in·situ retort ;s illustrated in Fig. 1.2. A downward·moving combustion front ;s supported by air blown in at the top of the bed and leaves burned-out shale above it as it progresses. Below the combustion front is a zone in which the temperature ;s sufficient f or pyrolysis to occu r, the organiC vapors generated from which are forced contact downward by the combustion air. with cooler shale which is at When the vapors come ; nto elevated, but subretorti ng, temperature in the condensation zone, part ial condensation occurs and the liqui ds flow downward over the shale to a sump from which the 0;1 is pumped to the surface. 10 AIR a RECYCL E GA~; -- ... .., ''. ,. , B U R~ED OUT ZONE " ... " Figure 1. 2 Schematic of a Vertical I n-Situ Retort, McCarthy and Cha (1976). Reprinted from Colorado School of Mines Qu ar terly, Vol. 71, No~ 4, by perm i ssion. II The present work was initially stimulated Robinson and Cook (1975) by the find ings of in examining core samples locations in the Green River Formation. from various They found that samples from the Utah core contained two to three times the amount of natura1ly occurring soluble material as did the Colorado and Wyoming cores. wh ich led them to suggest that a solvent extraction process for recovery of organics might be practicable for Utah shales. Work preliminary to the present study has indicated that a greater proportion of the kerogen in Utah oil shale can be made susceptible to solvent action by moderate heating than kerogen in Colorado oil shale. Wheelwright (1978) compared results for thermal solution of Hell's Hole Canyon. Utah shale in cyclohexane with data of Robinson and Currrnins (1960) for extraction of Colorado shale in tetralin. Sli9htly 9reater organic removal was re co rded in Wheelwright·s experiments than those of Robinson and Currrnins. even though the la tter re searche rs used a longer extraction time. Thorum (19791 compared the solubilities of Hell's Hole Canyon. Utah and Anvn Points. Colorado shales in shale oil l iquids , and observed greater organic removal from the Utah shale. Since the economics of a solvent extraction process for oil Shale are questionable. a more significant impact of the aforementioned findings may lie in the in-situ recovery method discussed previously. As hot condensed oil fl ows downwa rd over unretorted shale 1n an in-situ retort. there wou ld be sufficient contact time for the oil to dissolve a port i on of the bi tumen in the sha 1e. Si nee convers i on of kerogen to bitumen occurs at temperatures well below those requ; red for pyrolysi s of kerogen to oi l. it is conceivab le that the amount of bitumen 12 dissolved would content. be significantly greater than the natural bitumen Changes in product quality and yield could also occur due to thermal solut ion prior to the onset of pyrolysis. To further the preliminary studies of Hsiao (1978), Wheelwright (1978), and Thorum (1979), this study was underta ke n t o characterize the thermal solution process on a laboratory scale for Hel1·s Hole Canyon. Utah oil shale. It wa s desired to determi ne yields (as percent removal of ori gi na 11y present organ; c) obtai nable at subretorti n9 temperatures (275°·385°C) in the presence of either of tw o commerCially-pure solvents (cylohexane or tetralin) or a coal-derived l iquid (creosote oil). In these runs, 011 shale and solvent (0.14 grams of shale per milliliter of s olvent) were held at constant temper ature for 24 -hours. A non- 1sotherma 1 techn i que i nvo 1 vi n9 heat i n9 of the sha 1e and solvent at a constant rate was used to study therma l solution k.inetics in tetralin. Analyses of spent shale as well as the re covered organic matter were performed in order to determi~e the effect of processing conditions on the nature of the products of thermal solution as well as to aid in understanding the mechanism of the decomposit i on of kerogen to soluble material. CHAPTER 2 PREVIOUS WORK Hi star; ca 11y, act; vi t ; es 1eadi n9 to cOlIlTlerci a 1 development of 011 shale deposits and the intensity of scientific research on fundamental problems relating to utilization of the resource have been dictated by the size of known petroleum reserves. As producing fields dwindled 1n size and depletion of these fields was deemed "imminent, II the technology for recovery of synthetic crude from oil shale and other sources was great 1y advanced through 1ntensifi ed research efforts. time, however, At the same petroleum exploration activity underwent a parallel increase; the result of an extensive petroleum discovery was relegation of synthetic fuels production to a position of lesser importance. Recently, decreased demand for liqu id fuels in this country, partic- '. . ularly gasoline, has had such an effect on delaying commercialization of a synthetic fuels indust ry. 2.1 Solubility Studies Early resear chers studying solvent extraction of oil shale kerogen foun ct that only a small amount of the organic matter in oil shale could be extracted with common organic solvents for petroleum at their normal boll i ng points. Gavin and Aydelotte (1922) extracted shales from different regions of the United States, including several samples from the Green River Formation, in a Soxhlet apparatus with tetrachloride, carbon disulfide, acetone, benzene, and chloroform. carbon A 14 so 1ubl1 ity of from 10 to 18 percent of di st i llat; on y; e 1d. depend; ng on the solvent used, was noted for a sample from DeBeque, Colorado. A 30 gallon-per-ton New Brunswick oil shale was studied by McKinney (1924) and foun d t o be from 1.5 percent soluble in ethanol to 3.2 percent soluble in benzene (based on raw shale weight). Schnackenberg and Pri en (1 953) stated that kerogen is only soluble to the extent of two percent or less in tetra ch loride, co","on solvents carbon disulf i de. acetic acid. and cyclohe xano l such as benzene, chloroform. acetone, ethanol, carbon ethyl ether, at atmospheric pressure and the normal boiling point of the solvent. is It natura11y apparent fro m these occurring soluble data material that is only a present minor in amount on of shale. Extraction at the boiling point of the solvent is thus not competiti ve with re cove ry methods involving pyrolysis of the organic material. temperature solvent extraction interest to th ose intent 011. would, however, be of Low- considerable studying the nature of the soluble portion. since little structural alteration would occur during solution. 2.1 . 1 Thermal Solution While extrac t ions performed at the normal boiling point of the solvent result in little recovery of organic mate rial from oil shale, a considerable fraction of the organic material can solvent at elevated, but subretorting. temperatures be removed «400 0 C). by a Engler (1912) deduced that material he referred to as py robitumen, ordinarily insoluble , was rendered soluble when heated to temperatures as low as 200°C. Numerous patents have been granted for processes wh ich exploit the enhanced solubility of oi l shale organic material at moderate 15 temperatures. The first American patent was granted to Ryan (1920) for a method of extracting soluble material from finely crushed oil shale in a 1:1 mixture with heavy shale oi 1 at 315· to 370·C. Day (1922) received a patent for an apparatus designed to extract hydrocarbons from 2-inch shale particles using crude shale oil at 28S- to 370·C. A patent for a process using paraffin oil at 351- to 357-C to remove hydrocarbons from "bituminous sha l e -li ke material" was granted to Hampton (1928) . Additional patent literature on thermal solution. which includes a number of Australian and British patents, ;s too voluminous to review comprehensively. and l ack of experimental detail limits its scientific importance. Those processes cited here are representative of the earliest American thermal solution patents and illustrate that interest in the thermal solution process has been sufficient to stimulate the attention of a number of investigators. In an early study. McKee and Lyder ( 1921) noted that a soluble . intermediate, called bitumen, was formed as a primary product of thermal decompos it ion of kerogen . It was reported that approx imately 35 percent of the organic matter from a Parachute Creek, Colorado sha l e became soluble in carbon disulfide when heated to 41O-C, a substantial increase over the heating. two percent solub l e material that was extracted before The erroneous conclusion was forwarded that bitumen formation begins at a definite temperature between 400· and 410·C. Dulhunty (1942) described two experimental techniques by which he extracted organic material from Glen Davis (Australia) torbanite with benzene. The first technique involved preheating the torbanite alone for an ample length of time to allow conversion of insoluble matter to a 16 soluble form. followed by benzene extraction of the soluble components at 270°C and 560 psi for eight hours. Successively higher preheating temperatures re sulted in a cumul ative yield of 90.3 percent removal of organic material. Of the total extractable product9 81.2 percent was re moved after successive four-hour preheating periods at 340°, 360°, and 380°C; indicating that a significant change in the nature of the torbanite ha d taken place in the temperature range 340°_380°C. A yield of 90. 1 percent organic removal was found us i ng the second technique, that of heating th e t orbanite in benzene at a temperature suffi ci ent to produce soluble material formed. place and removi ng soluble products as they are It wa s postulated that a slight rrolecular rearrangement taking in the temperature range 340° to 360°C was responsible thermal de composi tion for render ; ng the organ; c materi a 1 sol ub 1e. Hub ba rd and Robinson (1950) stud ied Colorado oil shale fro m Parachute Creek and Rifle. of After heating to 350°C i n the absence of oxygen,- 50 percent of the organic material became soluble in benzene, while 87 percent be came soluble after being heated to 500°C. Formation of carbon residue was prevented by rapidly heating the sa mp les for short periods of time. Investigati ons of the applicabi lity of the thermal solution process for comme rcial production of liquid fuels were performed by D'yakova (1944) and Jensen et a1. (1953). D'yakova, us i ng 011 shales from the USSR, stud i ed bat ch and cont i nuous thermal solution us i ng anthracene oil and several shale-oil fractions as solvents. The optimum conditions to ma ximi ze yield (reported to be 90-95 percent of total organic) in the batch pro cess we r e found to be a tempe rature of 420°C and 15-mi nute 17 exposure to solvent for a sulfur-free shale and a 5-minute exposure at 385°-390°C for several shales ~ high-sulfur Choice of solvent and particle size in the range 0.15 to 5.7 nrn did not significant ly affect the yield. A yield of from 85 to 90 percent was reported from a 30- kilogram-per-hour continuous unit. The product slate in terms of gasoline, ker os ene. and gases was reported for both batch and continuous runs. In a U.S . Bureau of Mines study. Jensen et al . (1953) evaluated batch, semi-continuous , and continuous thermal kerosene, quinoline. and anthracene oil. organic removal at 420°C were quinoline as the solvent. solution 1n petroleum Yields as high as 90 percent reported in the batch tests using Extractio n under hydrogen pressure resulted in greater yields and produced a l ower-boiling extract. The thermal solution process was not considered to be a pract i cal corrmercial-scale shale-oil production process. The data of both D'yakova and Jensen et al. indicate a decrease in Ehe "effective solubility" at an extraction temperature higher than that which results in maximum yield. al. attributed this observation to the nat ure of the Jensen et analytical technique used to determine the fraction organic removed, since any coke depOSited on the shale by cracking of the extracting solvent was measured as unconverted organic material. 2.1.2 Extract Character An investigation was conducted by Schnackenberg and Prien (1953) to ga in information on the chemical constitution of kerogen and its decomposition fragments. A temperature of 200°C was used in all runs, and solvents of widely varying chemical and physical properties were 18 employed. In most cases. the carbon-to-hydrogen ratio of product extracts was found to be lower than that of kerogen as well as that of a Fischer Assay 011 . Nitrogen content was found to be l ower in the extracts than in kerogen and the Fischer Assay oil, and extract sulfur content was lower than that of kerogen. It was postulated that two f orms of kerogen exist: heteroatoms which produces polar groups upon decomposition, predominant l y hydroca rb on carbon . one rich in and poor in heteroatoms in and one relation to The latter form was hypothesized to contain the majority of the organic nitrogen and sulfur. Of a1' the solvents employed, tetralin was f ound to give the greatest yie ld (49 . 5 percent of Fi scher Assay yield) under the reaction conditions studied. Subsequent to the above work, a study by Thompson and Prien (1958) to further elucidate the structure of the organic matter dealt with the effect of the ratio of organic to i norganic matter and temperature on the extract i on process us i n9 tetra 1 in as the so 1vent. Samp 1es of 1ean and rich shales as well as a kerogen concentrate (44.4 percent ash) were heated for at least one hour at constant temperature. Their results s howed that the yield, in percent organic removed, wa s independent of shale organic content at 400·C, whi Ie at 200·C and 300·C, the yield varied inversely with organic content . Extract carbon·to·hydrogen ratio was observed to increase with increasing extraction temperature . A "dual-simultaneous " so lution mechanism, said to invo l ve either two forms of kerogen or two types of bonding mechanisms , was postulated . In another study carried out with the intent of determining the structure of kerogen, Robi nson and CUlTlTli ns (1960) extracted Mahogany 19 zone oil shale from Rifle, Colorado with tetral;n at temperatures ranging from 200' to 350'C for 24 to 144 hours . They remarked that very sma 11 amounts of gas were formed (a max i mum of 6 percent convers i on of organic to gas at 350·C.) and that no carbon re s idue was formed in any of their experimental runs. extracted in extracted. 48 hours, At 350·C, 84.9 percent of the kerogen was while after 144 hours, 94.5 percent was In order to study the composition of the extract, the tetralin was removed by steam distillation and the remaining material was separated into four pentane-insoluble material. fractions denoted as oil. wax, resin, and The oil fraction was further separated into polar, aromatic, and paraffinic fractions. At higher temperatures the oil fraction became more aromatic and less paraffinic. Nitrogen content of the extracts increased with temperature while the oxygen and sulfur content decreased. observation~ Based on this it was proposed that portions of the kerogen macromolecule which contain oxygen and sulfur were more easily degraded and made solvent susceptible, as opposed to nitrogen-c ontai ning structures whTch remained relatively insoluble at lower temperatures. saturated heterocylic Kerogen was described as conSisting largely of structures with lesser amounts of cyclic and straight-chain paraffins and a minor amount of aromatics. A study by Robi nson and Cook (1975). which reported that Utah oil shale contained from two to three times the amount of naturally occurring soluble material as other Green River shales~ stimulated" a series of investigations into the process of thermal solution using Utah oil sha 1es in the Chern; ca 1 Eng i neer i ng Department of the Uni vers i ty of Utah. The work of Wheelwright, Hsiao, and Thorum in this area is sum- 20 marized here due to its particular relevance to the present study . in that the experimental apparatus and procedures employed are nearly identical, thereby allowing direct comparison of their results with those of the present work. Thermal solution of oi l shale from an outcrop in Hell's Hole Canyon of eastern Utah in cyclohexane was studied by Wheelwright ( 1978). His results show a maximum of 89 percent convers i on of organiC to a soluble a 24-hour extraction at 344-C. Higher yields than those reported by Robinson and Cumm ins (1960) for extractions of Rifle. form for Colorado shale in tetralin were found even though the experimental conditions of Robinson and Cummins were more severe ~tetralin. a more powerful solvent than cyc l ohexane). the ability of shale oil shale~ (48 hours in In order to study it self to extract so lu ble material from oil Hsiao (1978) co ndu cted tests on Hell l s Hole Canyon sha le in the temperature range 298- to 350·C. Somewhat lower yields than those of Wheelwright (1978) as well as Robinson and Cummins (1960) were reported, varying from 25 percent at 298'C to 56 percent at 350'C. A direct comparison of the amount of material extractable from Hel1 1 s Hole Canyon and Anvil Points, Colorado shales was performed by Th orum (1979). Using sha le oil as the solvent, it was found that the y i eld from a 53-gall on per-ton Utah shale was considerably higher than that from a 85- ga11on per-ton Colorado shale under the same conditions of temperature and time. The standard method of retorting oil sha le to determine oil yield in gallons per ton, the Fischer Assay, results in conversion of approx i mate 1y 78 percent of the organi c matter to oi 1. gas. and water 21 (Allred. 1976). Allred (1976) also reported that 61 percent conversion of organic material to oi l is procedures for Green River oil typical of standard Fischer Assay shales. The standard Fischer Assay procedure involves heating a weighed 011 shale sample at a moderate heat; n9 rate (BOC per mi nute) to a maximum temperature of 500 0 e. then hold i ng the samp le at that temperature until large -scale above -ground production ceases. retorts designed for commercial generally achieve oil yields Fisher Assay oil yield. 011 approaching, production but seldom exceeding, Yie ld s as high as the 107.6 volume percent of Fischer Assay have been reported from the TOSeO II process, 98 percent from the Paraho retort, 102 percent from Union "BII retort, and 82 to 87 percent from the Gas comparison, a yield Combustion of 90 retort percent (Schora et al., organic removal 1977). i n the By thermal solution process (achieved at a temperature well below 50QoC) amounts to 147 percent of the oil yield and 115 percent of the yield of volatiles (Oil, gas, and water) from a Fischer Assay retort. 2.2 Kinetic Studies Studies of the rate of oil production from 011 shale are cortmon in the literature. Since the early work of Maier and Zimmerly (1924). a variety of experimental approaches have been used to eluicidate the mechanism by which kerogen decomposes as well as the kinetic parameters necessary to mathemat i cally describe the rate of decomposition; namely, the activation energy, pre-exponential or frequency factor, and reaction order. The complex nature of kerogen and the sensitivity of the experi- mentally observed conversion data to the physical characteristics of the experimental apparatus have resulted in nearly as many proposed 22 mechanisms as there have been kinetic studies (see Ta ble 2.1). It is beyond the scope of this work to re view all of the proposed kerogen de composit i on schemes and the; r merits (or faults); howoeve r. an overview of several such decomposition schemes is presented in order to i llustrate the variation in the complexity of postulated mechanisms. 2.2.1 Mechanism of Kerogen Decomposition McKee and Lyder (1921) correctly concluded that oil is not formed as a primary product of kerogen decomposition; howeve r, they erroneously concluded that a solid or semi-solid intermediate (bitumen) formed at quite a definite temperature " ••• between 400 0 and 410°C ••• 1I heating was said to result in decomposition of Further bitumen to oil. Subsequent work by Franks and Goodier (1922) showed that si9nificant quantities of bitumen were produced even at 3DOoC. Ma~er later, the work of and Zimmerly (1924) showed that bitumen formation was a function of the t ime and temperature-- of heating and that measurable amounts of bitumen were formed at 275°C. at even lower temperatures, immeasurably slow. first-order They postulated the formation of bitumen although the rate of formation was By mathematically treating bitumen formation as a reaction with respect to the amount of unconverted (insoluble) organic material, an expression for the rate constant, k. was determined fr om which an activation energy of 41.5 kcal/mole over the temperature range 275°C t o 365°C may be calculated. Cane (1948) found that measurable decomposition of Australian torbanite kerogen occurred at 20DoC, and CUnTllins and Robinson (1972) observed measurable decomposition of Green River kerogen at 15DoC over a period of 12 roonths. It appears that the minimum temperature at which 23 Fi gure 2.1 Ove rview of Proposed Kerogen Decomposition Schemes Hubbard and Robinson (1950): Kerogen----oa-Bitumen--+Oil + Gas + Carbon Resid ue Cane (1951): Keroaen ~ Ker0gen '--~ .... Rubberoid ---jIoo '" "" CO 2 + H2S H2S Naphtha Bi tumen ----+ 0; 1----+- Gas Coke Schnackenber9 and Prien ( 1953): Gases Kerogen ---;. Rubberoid ---+ Bitumen .."...". CO 2+H2S CO 2+H2S+H20 Oil---+ Volatile Oil Co ke Allred (1967): Gas Kerogen - -.... Bitumen Carbon Residue ---<.~ (Oil + Gas)liQ -_ .. (Oil + Gas)vap Shul'man and Proskuryakov ( 1968): ~ Vo latiles 6 Aspha 1tenes 1-... Aspha l tenes 3 ...... Mal thenes 3 ~ Carboi ds 4 / ..,. Vo latiles 5 """ Carboids 3 ..... Vo latiles 7 /' ,...:9" Vo latiles 3 Kerogen - + Ma lthenes 1 ------... Asphaltenes 2 ---+ Ma lthenes 2 ~ Carbo; ds 2 ~ ~ Vo latile s 2 ""'M. Carbo i ds 1 ~ Volat ile s 4 Vo latil es 1 24 Fi gure 2.1 (continued) Fausett et a1. (1974): Kerogen , Bitumen Bitumen > Oil + Gas Kerogen + Bitumen , Bitumen + Bitumen Kerogen + Bitumen Kerogen + Bitumen > Bitumen + Oil + Gas , Bitumen + Coke 25 kerogen decomposition may be observed depend s somewhat upon the patience of the inve s tigator. In fact, Cane (1951) has stated that there is no theoretical lower limit to the onset of the decomposition. Torbanite kerogen decompos it i on to a so 1ub 1e form was observed to proceed vi a a distinct int ermediat e given the name "rubberoid. 1I whi ch resulted from the occurrence of gentle cracking and was accompanied by the liberation of a small amount of gas decompose further formed . (Cane, 1951). to bitumen, The rubberoid was said to from which oil, gas, and coke were The activation energy for bitumen production in the temperature range 350' to 400'C was found to be 48.5 kcal/mole. Rubberoid was also included as an intermediate in kerogen decomposi tion first to soluble bitumen then to oil, gas, and coke in a mechanism postulated by Schnackenberg and Prien (1953) in a study of thermal solution at 200'C. Hubbard and Robinson (1950) found that the primary decomposition products of kerogen ultimately, carbon were gas residue and soluble bitumen. were formed by Oil, additional gas, heating. and, A consecutive reaction mechanism is suggested by the values of activation energies determined from the calculated first-order rate constants which are: 27 kcal/mole for temperatures below 437'C and 11 kcal/mole for temperatures above 437-C. In taking into account the induction time in analyzing the data of Hubbard and Robinson (1950), Braun and Rothman (1975) calculated activation energies of 10.6 kcal/mole for temperatures above 487'C and 42. 4 kcal/mole for temperatures below 487' C. The existence of two consecutive first-order reactions was also postulated by Braun and Rothman. 26 An ex amp 1e of the decomposition schemes ext reme camp 1ex ity of some proposed kerogen i s that put forth by Sh ulman and Prosk uryakov (1968) for 8altic shales whi c h incorporates no less than 17 di st inct first-order reactions. Excellent ag reeme nt between the predicted and measured product yield was reported for isothermal pyrolysis at 371-C . Use of the technique of thermogravimetric analysis (TGA) in kinetic studies of kerogen decomposition has increased since 1965 . Values of kinetic parameters may be determined from TGA data by a number of methods, from which mechanistlc features may be inferred, although some prior knowledge of the reaction mechanism is necessary to apply many of the method of analysis. Usin9 the TGA technique, Allred (1967) concluded that a simple kinetic expression was inadequate in describing kerogen pyrolysis and proposed consisting of three reactions. a partial decomposition mechanism Bitumen decomposition to 0;1 and gas was said to be rate·controlling below 482·C with an apparent activation energy of 40 . 5 kc a 1fmo 1e . At hi gher temperatures I decompos it ; on of kerogen and/or transfer of volatile matter out of the inorganic matrix wa s found to be the rate- cont rolling step. A logistic or autocatalytic rate expression fit the experimental data best, which sugge sts that the rate of kerogen present. decomposition depends on the amount of bitumen In a number of other studies. the second-order autocatalytic effects of bitumen have been incorporated into a kinetic model (Fausett et al • • 1974; Wen and Yen, 1977; and Finucane et al . , 1977). Haddadin and Mizyed (1974) studied the kinetics of the pyrolysis of Jordan 011 analysi s shale the data at temperatures of from 280· to 51S ·C. led them to suggest that kerogen Integral decomposition 27 proceeded via a diffusion-controlled, activation energy of 9.8 kcal / mole. heat i n9 TGA stud i es were performed first-order reaction with an Constant.temperature and linear- by Campbe 11 et a1. (1978). who determi ned va 1ues of act i vat i on energy and pre-exponent i a 1 f actor by fitting data for the rate of 011 production to an equation for the rate of product evolution which was derived by Van Heek et a1. (1967). A first-order dependence of the decomposition on unconverted kerogen was assumed and a heating rate of 2·C/min was used. An activation energy of 52.7 kcal/mole and a pre-exponential factor of 1.8xl0 1S min- l were found to best fit the oil-production data, Additional TGA work. using linear heating of the sample has been carried out by Shih and Sohn (1980) and Rajeshwar (19S1). Several meth ods of data analysis were used to determine kinetic parameters in each paper. Shih and Sohn (1980)9 using four different heating rates, determined that first-order kinetics were followed for oil generation with an activation energy of 47.7 kcal / mole and a pre-exponential factor of 4.9xl0 13 min-I. They recommended use of an overall first-order rate expression to predict oil production from oil shale. Rajeshwar (1981)9 us i n9 heat i ng rates of 5, 10 t and 20· e/mi n t reported the average va 1ues of kinetic parameters determined from each of three methods of data analysis used reacti ons for assuming the existence of two consecutive first-order kerogen decompos it i on. An act i v at i on energy of 14.8 kcal/mo1e and a pre-exponential factor of 3.3x10 6 min- 1 were calculated for the bi tumen. first of the two react ions 9 the convers i on of kerogen to For the subsequent decompos i t ion of bi tumen to oi 1, gas 9 and semi-coke residue, the activation energy was found to be 36.1 kcal/mo1e and the pre-exponential factor was 9.8xl0 13 min-I. 28 As pointed out by Rajeshwar et a1. variation in rep orted decomposition of 0;1 kcal!mole and values shale. of (1979). there kinetic parameters is a wide for thermal Act ivat ion energies range from 5 to 57 pre-e xponential factors vary from 10 2 to 10 20 min-I, Equally variable are the proposed decomposition schemes, encompassing simple one-step mechanisms Proskuyakov (1968). and the 17-step mechanism of Shulman and While the majority of researchers have found that first-order rate expressions fit experimental data adequately, a number of investigators have used second-order models to account for the poss ible autocatalytic effect of bitumen on kerogen conversion. Sens it; vity of exper i ment ally observed kerogen conversi on to the apparatus and procedure followed may account for much of the variation in reported kinetic parameters, since restriction of the transfer of reaction products out of and away from the sample caused by the design of the experimental apparatus result lower values of in calculation of significantly activation energy than breaking processes. expected for chemical bond The complex nature of the material being studied as well as some uncertainty of the chemical structure of that material also cont ri bute to the wi de range of reported k; net; c parameters in th at experimental data no doubt represent the simultaneous occurrence of a multitude of chemica l reactions Itaveragedll to account for but a few observable changes in the nature of the organic matter. Additionally. accurate experimental determination of kinetic parameters for a multistep reaction, as the majority of researchers have proposed for kerogen decompOSition. is difficult at best. A better approach. as has been done in the present work, may be to study one step of a given reaction 29 mechani sm us; ng an experi menta 1 arrangement such that the occurrence of other reactions is suppressed. 2.2.2 Thermal Solution Kinetics By heating oil shale in the presence of a solvent of relatively low volatility (so that predominantly liquid solvent is present). the rate of formation of thermally-produced soluble bitumen may be studied. Haddad;n (1980) has performed such a study using Jordan oil shale. The tetralin extraction of minus 200 mesh shale particles was studied in the temperature range 229°_315°C. Kerogen conversion vs. time data from constant temperature runs of up to 1000 minutes duration were temperatures of analyzed from assuming by 229 0 to 260°C, (about 17 hours) first-order an kinetics. activation energy At of 9.0 kcal/mole was calculated, while at higher temperatures (260° to 315°C), a higher extract value of production 20.5 kcal/mole was calculated . which .. accounts diffusion for A ~chani limitations sm for at low temperatures was proposed: Kerogen ~ )j T<260 0C Bitumen ---...,... Extract k3 k, T>260 0C. Asphaltene -.,------;.... Oil - - -...... Extract k-3 Slight pyrolysis was said to occur in the higher temperature range while a diffusion-controlled kinetic mechanism was said to predominate at lower temperatures, although the interpretation of representative of diffusion limitations is questionable. the data as Use of the term "011" in this rrechanism implies that significant thermal cracking 30 of the bitumen ha s occurred . At the t emper ature s used, however , very little thermal alteratio n of the bitumen would be expected and no produc t analysis wa s pr ese nted to justify the us e of the term "oil " in describing the high temperature product. mechani sm s ugge sted by the The competitive react ion low activation energy calculated for low temperatures and the h igh acti vation energy at high t empera tures i s a notewor thy depa rt ure from the consecutive mechanism postulated by so many inve st igators. In a later paper by Haddadin (1982), product analy ses of tetralin extracts and pyrolytic oil fr om Jord an 0; 1 shale showed that tetralin had entered into the rea ct ion somewhat, resulting in improved carbon-to-hydrogen ratio s and lower su lfur content of the e xtract as compared to the oil. In s urveying th e ava i lable literature. it i s apparent that st udy of the products attention. obtained except f or from the thermal wor k of solution has Schnackenberg received and Pr ien Th ompson and Pr ien (1958), ' and Robinson and Cunmins (1960) . pap ers , elemental little (1953) . In those anal ys i s and chemical fractionation of the ext racts was pe r f ormed , but no analy s is of the s pe nt shale was reported. the effec t of the chemica l While pr operties of the so l vent on the extra ct character was studied by Schnackenber9 and Prien (1953) . no s tudie s of the ability of a su percritica l or gani c solvent to extrac t organi c matter from oil s hale are available . Superc ritic al extra c tion of coal. lignite. and wood ha s bee n studied to a greater extent (Whitehead and Wiliams, 1975; TU9rul and Olcay, 1978; and Ca limli and Olcay, 1982) and ha s been shown t o be an effective means of removing organic material from t hese materia l s . 31 The ki net i C5 of the therma 1 so 1ut ; on process has not been extensively studled; only the recent work of Haddadin (1980, 1982) has focused on determining the rate of product ion of sol uble material. That study of Jordan oil shale included only a limited temperature range (229°-315°C). however, and it would be expected that oil shale of different depositional and geologi cal different behavior upon decomposi tion. hi story might e xhibit While the potential quite for an economically competitive (compared with pyrolysis retorting) recovery process based on thermal solution of kerogen is admittedly low, IOOre detailed study of the dis solution process is justified since increased knowledge of the nature of oil shale kerogen and the mechanisms by which it decomposes would result. CHAPTE R 3 EXPERIMENTAL In th~s sect ion the expe ri mental strategy will be de sc ribed along with details of the apparatus used and procedure followed i n carrying out the study. 3.1 As mentioned Experimental Plan previously, observat ion that Utah shales this conta~n study was stimulated by the from two to three times the amount of natu ra 1'y occu rr i n9 sol ub 1e I'Mteri a 1 as other sha 1es of the Green River Formation (Robinson and Cook, 1975). The original intent of the investigation was to study the implications of the enhanced solubility of Utah Shales on an in-situ recovery operation re ga rd ing yield and product quality. based on the premis e that significant amounts of organic matter could be e xt racted by the solvent act ion of produced shale oil flowing past areas of elevated, but subretorting, temperature in the fractured bed. As the project evolved however, it became a characterization of thermal solution of oil shale kerogen at ITI)derate (275°-410°C) temperatures. previously, While s imila r studies have been performed many have been limited in scope to study of variables influencing yield (O·yakova, 1944; Jensen et al . , 1953) and in several cases, product composit ion (Schnackenberg and Prien, 1953; Thompson and Prien, 1958). no published With the exception of the recent work of Haddadl n (1980 ), data are available dealing with the kinetics of the 33 extraction appropriate. process; consequently, a kinetic study was deemed Additionally, the present study includes analysis of the spent shale -- essential information for retorting processes designed to rely on combustion of residual carbon for heat generation, as well as in cons i de rat i cns of the env; r onmenta 1 ; mpact of spent sha 1e di sposa 1 from such a process. The effects of extraction temperature, organic content of the shale. solvent properties, and solvent-to-shale we igh t fraction of originally present organic material solution have been studied in this work . ratio on the removed by thermal liquid and solid reaction products were collected for further analysis to ascertain the influence of the aforementioned parameters on the nature of the products. It was also desired to carry out a kinetic study to determine the rate of decompOSition of kerogen to a soluble form. In pl anning the kinetic study, two criteria were set: to eliminate the effect of the induction or heat-up time on the observed conversion, and to min~m1ze the effect of mass-transfer limitations in removal of soluble mater~a1 from the shale (the conversion of kerogen to a soluble form should be the rate-limiting step, soluble mater~al rather than the transfer of from the shale to the bulk solvent). By performing expe rime nts in such a way that these criteria were met, the i ntrinsic rate of conversion of kerogen to soluble material was determined. As Figure 3. 1 shows, an induction time of fr om two to three hours was unavo idable in constant-temperature runs due to the large thermal inertia of the autoclave used. An isotherma l kinetic study would require runs of varying duration at a number of different temperatures FURNACE --- 1--2-3 HRS ~ , , \ " \ INTERIOR .... '"=> .... .... .... s ~ :EO TIHE .... ~ Figure 3. 1 Schematic Diagram of Furnace and Vessel Interior Temperature Traces for a Constant-Temperature Run Illustrating the 2-to-3 Hour Induction Period and the Rapid Cool-Down at the End of the Run ... w 35 1n order to temperature. total run duration. determine conversion as a function of time and The induction time would be a significant fraction of the time. especially for higher temperature runs of short The occurrence of measurable conversion before a constant temperature was obtained would introdu ce error into the data if the total conversion in the constant tempera tu reo run was (1950) by Braun ha ving occurred at that conversion which occurred duri ng the The analysis of the data of Hubbard and Robinson and Rothman correct ion. In; nterp ret i n9 assumed the that as It wou 1d be di ffi cu 1t to actu rate ly correct the measured conversion for that induction period. tak.en samples (1975) was an the; r data t reached own constant attempt to make such a Hubba rd and temperature Rob; nson immediately. Braun and Rothman calculated an induction time for each temperature used in Hubbard and Robinson's experiments and assumed that no conversion took place during that time. Neither analysis satisfactorily accounts for conversion during the i nauct~on period, however. and other researchers later questioned the analysis Kowallis (1977) of Braun and Rothman. In the present work, a linear-heating technique was used in the kinetic study to circumvent the inaccuracies presented by the existence Of a Significant induction period. This technique involved heating the sample at a constant rate from a low temperature (at which no measurable conversion occurs) to some maximum temperature after whi ch the reaction was quenched. As is evident in Figure 3.2, no error-inducing induction period is present in the tempera ture-t ime trace of the sample, since the rate of tempe rature increase of the interior of the vessel becomes FURNACE ... '" .... ...;;:! ... .... :> INTERIOR a. :0: TIME ~ Figure 3.2 Schematic Diagram of Furnace and Vessel Interior Temperature Traces for a linear-Heating Run. The Rate of Temperature Increase of the Interior Becomes Constant at About 150· C. w '" 37 constant at about 150°C. Since no rreasurable conversion occurs below this temperature, it can be assumed that all decompos i tion occurs during exposure to a linearly increasing temperature ramp. Satisfaction of the second criterion. that of minimizing the effects of mass-transfer restrictions, was accomplished by us i ng a very slow heating rate -- O.2°e/mi n. material i s produced at Slow heat~ng should insure that soluble a slower rate than that at which it is transferred to the bul k solvent. Previous researchers who have employed thermograv imetric analysis, a similar techn iqu e involving linear sample heating, have used higher heating rates of 1.52 °C / min (Allred, 1967), 2'C /min (Campbell et a1.. 1978). and 5 to 20 'C/min (Rajeshwar. 1981). In many cases. the experimental design was such that 011 was produced faster than it could di ffuse out of the shale, resulting in the observation of data which represented the physical process of masstransfer of oil out of the shale rather than the thermochemi cal process ~ of oil production from kerogen. 3.2 Expe rime ntal Apparatus and Procedure Experimental runs were carried out in a one-liter, bolted-closure autoclave, steel serial number 77-9316-1. by Autoclave Engineers . manufactured from 316-stainless A maximum allowable working pressure (MAWP) of 5800 psi at 343'C was quoted by the manufacturer. schema tically shows the vessel and its features. Figure 3.3 The vessel was roounted on a steel stand wh ich also supported the electri c motor used to drive the impeller. An annular electric furnace was placed around the lower portion of the vessel, which rested on a refractory disk to reduce convection currents in the bore of the furnace. The furnace was 38 PRESSURE --GAUGE MAGNETI c: BELT VALVE ..... _._ _---....... _- .... ---_ ... -- --- [f-l':n...., ./" COOll NG WATER ............. INL£T FOR DRIVE .......... SYSTEM I:: J I BOLT FOR LID I I I I ,---r " • 1:1 I •• I I I 'I :: ,I " , " " -~ -' -LID I :: I:: I I ••, . STAINLESS I I I I :: !: STEEl GASKET SUPPORT PURGE INLET COOllNG C:OIL I I dlll:"J _---J: L __ ... IMPE LLER Figure 3.3 Schematic Diagram of the I-liter Autoclave Used i n Batch Thermal Solution Runs Illustrating its Major Components 39 supported by a scissors jack which allowed it to be raised or lowered as desired. The pressure inside the vessel was monitored by a 3-1/2 inch dial pressure gauge. Severa l gauges of differing ranges were used due to the large variation in autogenous pressure depending on the solvent and temperature used . A thermowell downward into the vessel from the lid . and purge inlet tube extended The thermowel1 reached to within 1-1/2 inches of the bottom of the vesse l. ensuring its contact with the contents and rapid response of the type K thermocoup l e to samp l e temperature fluctuations. A helical coollng coil was connected to the interior of the lid, allowing the temperature of the contents to be rapidly decreased upon circulation of water through the coi l . Eight hex-socket bolts held the lid in place and provided sealing pressure on the stainless-steel gasket between the l id and the body of the vesse l . The gasket and sealing surfaces were cleaned thoroughly with either cyclohexane or acetone prior to cl osure . lead - base, high - temperature ant i -sei 2e compound was iPP 1i ed to the threads of the bo lts before tightening . In tightening the bolts , it was important to exert evenly distributed force on the lid so as not to distort it . To ac hieve an even l y distributed force, diametrica ll y opposed bolts were snugged down gradually until all eight bo l ts were secured . The bolts were then tightened incrementally unti l a torque of 125 foot-pounds was applied . This torque is above the manufacturers recommendation of 90 foot-pounds, but was found to be necessary to effect a gas-tight sea l. A magnetically-coupled drive system provided sample agitation, thereby eliminatng any axia l or radial temperature and concentration gradients within the vesse l. Use of the magnetic drive eliminated the 40 need for pa cking seals in the lid since the external drive magnet actuated internal magnets attached di rectly to the impeller shaft. A 1/4-horsepowe r vari able-speed electric IOOtor allowed impeller speeds of from 0 to 1500 RPM to be used. A setting of " I" on the speed controller, corresponding to an impeller speed of 150 RPM, was used in all runs. Oil shale sa mp les were selected from large blocks stored on the first flo or of the chemical en gi neering laboratory. These samples were collected fr om an outcrop in Hell's Hole Canyon, a side canyon of the White River located about 10 miles southeast of Bonanza. Utah Figu re 1.1) . (see Several blocks of differin g grade were selected based on an estimate of their oil yield in gallons per ton calculated from a density Canyon versus oil Fischer Assay Shale by Schmidt correlation de ve lo ped for (1977). The blocks Hell IS Hole selected were subsequentl y re duced 1n size by a jaw crusher and screened to obtain - 8+28 mesh part ic les which were stored in glass jars. total of f i ve blocks were used in experimental runs. Samples from a Analyses of the f ive sample lots are given in Table 3.1. A samp 1e charge to the autocla ve cons 1s ted of app roxi mate 1y 70 grams of shale and 500 milliliters of solvent. (It was shown that this solvent-to -sha le wei ght rat io was well above that wh ic h would affect the y1 e 1d at a g1 ven temperatu re -- see Fi gure 4.1. Runs made wi th other solvent-to-sha1e rat i os were carri ed out by using 70 grams of shale, then adjust i ng the volume of so lYent added to obtai n the des i red va 1ue of the rat io .) After charging the vessel, th e lid was bolted on as pre vious ly descr ibed , the furnace was raised around the lower portion of 41 Table 3.1 Analysis of the Five Hell's Hole Canyon Oil Shale Samples Used in this Work Shale Samp le Shale sp. gr. Schmidt yield (gal/ton)a A 8 C 0 2.26 1 .96 1.69 1.79 17.5 E 35.264.654 .4 Fischer Assay oil, 9al/ton wt. % 62.0 23.74 H20, 9al/ton wt.% 3.2 1.33 2.6 1.09 1.9 0.78 Coke, wt. % 8.95 6.93 4.92 Gas + 1055 9 wt. % 5.21 4.17 4.41 60.77 69.21 73.51 74.85 10.44 1.31 1.674 1.500 75.06 75.42 75.46 10.42 9.85 10.46 1.49 1. 79 1. 73 1.665 1.567 1.663 1. 701 2.034 1.965 81.36 10.55 2. 16 1.556 2.276 88.7 80.3 60.3 74.3 Ash, wt. % Organic Composition C, wt. % H, wt. % N, wt. % H/C N/C (x 100) Ash, wt. %b 50.5 43.5 18.60 16.38 70.3 a gallons per ton ca l cu la ted from Fischer assay/specific gravity correlation (Schmidt, 1977) b determined by oxidation at 450·C. inert weight 42 the vessel. and nitrogen pressure was applied to the interior to ve rify that all seals were tight. Periodically. a check was made prio,r to a run to ensure that no minute, undetectable leaks had developed due to unevenness of the sealing surfaces. This test was performed by pressurizi n9 the vessel to 500 -600 psi 9 with nitrogen. then c10s1 ng the inlet and outlet valves and allow~ng the vessel to stand overnight . If no detectable loss of pressure was observed, the run was continued. Several times when the vessel failed this test, ret ightening the bolts resulted in a gas-tight seal. loosening then On two occasions, it was necessary to re-mach1ne the sealing surfaces of the lid and body of the autoclave to the manufacturers specifications and replace the gasket before the pressure test was passed. After establishing a gas-tight seal, nitrogen was used to purge oxygen from the system, thereby suppress; ng oxi dati on react i ons. The motor was started (speed control setting "1") and power was supplied to < the f urnace. temperature Depending on the type of run to be made (constantor l inear-heating) , one of two types of temperature controllers was employed. For constant-tempe rature runs, a dual-input controller a consisting controller which was control of the of Barber-Coleman supplied furnace model 523B proportio nal by Autoclave Engineers was used for temperature. Figure schematic for the constant-temperature runs. 3.4 shows the wi ring As seen in Figure. 3. 4, the controller input consists of both the furnace and specimen thermocouple Signals. Chromel-alumel type K thermocoup les were used. Although the manufacturer stated that the controller characteristics were ITBtched to the therma 1 inert ia of the autoc 1a ve to provi de rap; d heat -u p with , T.C I ~ o. •• ~ REACTOR VESSEL 2-PEN RECORDER • • FURNACE T.C. SIGNAL TO CONTROLLER t::: ~ Z:::: El 0 ~ TEMPERATURE CONTROLLER ~ ~ ~ :::: t I:::: CONTROLLER OUTPUT 120 VAC Flgure 3.4 Schematlc 01agram Showlng Apparatus and Wlrlng for Constant-Temperature Runs ... w 44 m1 nimum overshoot t some tr1 a l-and-error was necessary to ascertai n the correct specimen and furnace set points requililed to ach i eve a desired specimen temperature. In the case of linear-heating runs, a Lindberg model 59554-C3 progralMlable controller was used. This unit allowed for a progra nmed tempe ratu re ra mp of from 0.1 to 9.9 °Ctmi n to be app 11 ed to the sample. In us ing this controller, it was necessary to operate it manually up to about 140°C since, due to the needs of a previous application, automatic control was not possible at lower temperatures. As seen i n Figure 3 .5, the controller was wi red such that the furnace tempe rature, increased. rather than the Fi gure 3.2 shows a specimen typ~cal tempe rature, was linearly temperat ure-t i me trace for both the furnace and specimen for a temperature ramp of 0 .. 2°C/min.. initial nonlinearity 1n the traces is due to manua l The operation wh1ch causes a rapid temperature rise into the regime of automatic control. after wh ich the traces become linear and approximately parallel. measured on the strip-cha·rt record. As the temperature increase of the 1nterio r varied from 0 .. 190 to O.197°C/min for a furnace ramp sett1ng of O.2°C /mi n (measured to be from 0.21 to 0 .. 23°C/min) . Due to 1ncreased heat flux from the unheated and uninsulated upper portion of the vessel at hi gher tempe ratures. the specimen heating rate decreased to 1ts l owest value near the end of runs to high temperatures (>385°C). Constant-tempe rature runs were of 24-hours durat10n. l1near- heating runs proceeded for from 10 to 22 hours. depending on the maximum temperature reached. At the conc1us10n of a run. power to the furnace was turned off. the furnace was l owered away from the autoclave. and water was circulated through the cool i ng coil to rapidly decrease the sample temp erature at approximately 20°C/min. I • , •• REACTOR 2-PEN RECORDER VESS EL •• 0 • e-; FURNACE T.e. SIGNAL TO CONTROLLER jooDDD D ~LER r:f;:: V :::: ;:;;:; OUTPUT FURNACE PROGRAMMABLE CONTROLLER 10 I 120 VAC DIGITAL TEMPERATURE READOUT Figure 3. 5 Schematic Diagram Showing Apparatus and Wiring for Linear-Heating Runs ... ~ 46 When the vessel rea ched room tempe rature, the cooling water was shut off. the drive system was disabled, and any residual pressure was vented before removi ng the lid. were unscrewed and the The eight bolts used to secure the lid 11d was removed . Any mater; a1 coat 1n9 the cooling coil and impe ller was carefully washed back into the vessel wi th clean solvent. A peristaltic pump was used to transfer most of the vessel contents into a clean beaker. The last traces of solids were removed vessel by repeatedly m111i1iters of solvent. flush i ng the with about 20 to 25 The slurry was then poured into 50 milliliter centri fuge tubes and spun at appro ximate ly 1000 RPM for 15 mi nutes. Centrifugation resulted in recovery of essentially all of the f i ne shale partic les which were suspended in the l iquid phase. These fine solids resulted from partial disintegration of the shale due to contact with the impeller. interior walls. cooling col1. and other shale particles. The extent of di s i ntegrat i on depended in part on the extent of removal by the solvent of the organic "cement" from the shale. thereby weakening the rema i ning inorganic structure. Recovered solids were placed in a Whatman Single-thickness cellulose extraction thimble. 43 x 123 mm size, and were rinsed with refluxing cyclohexane in a Soxhlet apparatus until the eluent appeared clear and colorless. Any organic material which was rendered soluble i n the thermal solut ion process was removed from the Shale i n th is process. A Precision Scientific vacuum oven, catalog number 68351, was used to remove the last traces of cyclohexane from the shale at 100°C, resulting in a clean. solvent-free solid product. under partial vacuum, and a small The oven was operated flow of air was allowed to pass 47 through the oven by opening a valve on the lid of the oven . This air flOft' was found to hasten the drying process ; f our to five hours proved to be adequate time to remove all the cyclohexane. After coo11ng 1n a desiccator to room tempe rature. the extraction thimble and spent shale were After this weighed. step in the procedure, the spent shale appea red ei ther as a fi ne powder or as pa rt ; c 1es approx; mate ly the size of the or; 91 na 1 raw sha 1e. except for some round; n9 of sha rp edges due to attrition. Powdered shale was observed to result from high temperature runs (T >350°C ). while runs at temperatures below about 310°C resulted in spent shale which appeared to be a mixture of both fine powder and lar ge r particles. Based on these observations. there seems to be a temperature range (which depends on the organic content of the shale) above wh i ch the shale part i cles were largely disintegrated. In order to determine the fraction of originally present organic material wh i ch was removed by thermal solution, a portion of the dried spent shale was pyro'yzed~ and oxidized. A Norton model 1133 tube furnace and a Varian mode l 901 - 2075 proportional controller were used 1n this procedure. Figure 3.6 is a schematic diagram of the apparatus. In carrying out this operation , a two-to-four gram sample of spent shale was first weighed in a tared aluminum boat. The boat was then placed on an aluminum ladle and inserted to the midpoint of the tube. alumel A chromel- type K thermocouple was attached to the ladle to measure the temperature and generate the input voltage to the controller. The temperature was maintained at 450°C for a duration of three hours. the first 30 minutes, the tube was volatile organic material. swept with nitrogen to For remove Any nonvolatile organic was then oxidized by THERMOCOUPLE SAMPLE / SAMPLE fOLDER FUME HoOD ~ QUARTZ TUBE \ -=- -=--=- =--= -= -=--= =--= - ------- - -~ '/ TUBE FURNACE / QQ ROTAMETERS '-= rTEMPERATURE CONTROLLER ®® --{><}- N2 ... " !7 Ffgure 3.6 Schematfc Dfagram of Tube Furnace Used to 'Oxfdfze Organfc Resfdue fn Spent Shales -<> '" 49 metering pure oxygen through the tube for the remaining 150 minutes . A rubber stopper with a 1/ 4-1 neh hole bored through it was placed in the outlet of the tube to prevent back-diffusion of air into the tube . At the conclus ion of the procedure, the sample boa t was removed from the l adle and pla ced in a desiccator to cool to room temperature. After cooling, the boat was weighed to determine the fractional weight l oss. At 450°C. decomposition of the inorganic carbonates in Green ~ve r shale is neg l igible (Heistand and Humphries, 1976; Shen, 1977), so that the weight loss in the oxidation process was that due to removal of organic matter remain~ng Samples of in the shale after the thermal raw oil solution process . shale were also analyzed by this technique to determine the we ight fraction of organic material in the raw shale. The mass balance procedure by which the extraction yield was calculated is detailed in Appendix A. It should be mentioned that the entire procedure. proceeding from raw shale to organic-fre.e ash, complete. required from three to four days to This was due to the fact that only one of each major piece of equipment was available . It is strongly recommended that, in future studies of this nature, additional autoclaves be utilized . By employing additional auto claves. more data could be procured in a more practicable manner . Three solvents were used in this work: Eastman cyclohexane, Dupont technical (tetral;n), and creosote oi l. grade o~l. grade 1,2,3.4 -tetrahydronaphtha1ene These solvents were used "'as received," with no further preparation or pur i fication . creosote practi~al Specifications of the obtained from Reilley Tar and Chemical Company of Ironton, 50 Utah, are listed in Table 3.2. The extraction temperature in all runs was above the critical temperature of cyclohexane, 280·C. Extractions wi th eye lohexane are thus cons i dered to be supercrit ieal or "dense·gas" extractions. Since the critical temperature of tetralin is 446-C, all runs wi th th i s so 1vent, as we 11 as those made wi th creosote 0; 1, are considered to be liquid-phase extractions. Although both liquid and vapor phases of tetralin and creosote oil exist in equilibrium at the temperatures used, the vapor phase ;s expected to have 1 ittle or no solvent power due to its low density. 3.3 This section characterizing Analytical Methods describes liquid and the analytical solid materials techniques in this employed study. in Carbon, hydrogen, and nitrogen elemental analysis was performed on both sol id and liquid samples and simulated distillation by gas chromatography was used to samples. determine the boiling point distribution of the liquid Carbon-13 nuclear magnetic resonance (nmr) spectroscopy using cross-polarization and magic-angle spinning (CP/MAS) was employed to determi ne the re 1at i ve amount s of aromat i c and ali phat i c organ i c carbon in the oil Shale samples. Details of the theory behind the latter analytical technique are omitted; however, a brief explanation of the underlying principles is included to orient the reader as to the abilities and limitations of the technique. 3.3.1 Elemental Analysis Simultaneous determination of the weight percent of carbon, hydrogen, and nitrogen in a sample was accomplished using a Perkin-Elmer 51 Table 3.2 Amer i can Wood Preserver's Assoc i at ion Standard PI-78 (revised) -- Standard Specifications for Creosote Oi l Specification not less than not Ill:lre than 1.5 Water, percent by volume Distillation. percent by wei ght. water-free up up up up up to to to to to 210·C 235·C 270·C 315·C 355·C 10.0 40.0 60.0 2.0 12.0 35.0 65.0 77 .0 52 2406 elemental analyzer. The operating pri nciples of the machine are briefly sUl11T1arized as follows: a sample of known weight is combusted in pure oxygen at a controlled temperature. The combustion products are catalyti ca lly converted to carbon dioxide, water , and molecular nitrogen then swept to a thermal conductivity detector, the out put of which is converted to a mi 11 i vo It-l eve lsi gna 1 for each spec ie and is reg i stered on a strip-chart recorder . By combusting a standard materia l (acetan i 1i de) of known element a1 compos it ion, three convers i on factors are calculated to tran sform the millivolt reading for each of the three e l ements to mi 11 ; grams. The wei ght percent of ea ch element may be calculated since the total sample weight is accurately known. volatile material) combustion. was determined by weighing the Ash (non- residue A Perkin-Elmer AD-2Z microbalance wa s used after for all weighings . The combust ion 450·C . temperature was controlled at either 950· or At the higher temperature, decomposition of inorganic carbonates present in the mineral portion of the shale occurred, which resulted in determination of the total carbon (organic plus mineral carbonates) in the sample. The lower combustion temperature was used in following the method of Hei stand and Humphries (1976) to measure organic carbon, hydrogen, and nitrogen (decomposition of the mineral matter for this shale, specifically carbonates , has been shown to be negligible at 450·C). mil l igrams Thi s method required as compared with a somewhat 1 to larger sample 3 milligrams for (5 to 7 total carbon determination), si nce the organic content of the spent sha l es was generally quite small . The combustion period was also extended from the 53 usual 2-1/2 minutes to 6-1/2 minutes to ensure complete volatilization of all organic material. samples were ground In preparation f or elemental analysis , solid in a Spex model 8500 shatterbox consisti ng of a heavy, hardened-steel pu ck and ring spun around the inside of a closed hardened-steel dish at approximately 900 RPM. A fine, homogeneous powder resulted from grinding in the shatterbox . Analysis of liquid extracts required removal of solvent in order to make meaningful measurements . Due to the complexity and wide boiling rang e of creosote 0; 1 as we 11 as the added comp 1i cat i on of probab 1e reaction of components of this solvent with extracted material, no attempt at analysis of creosote 0; 1 extracts wa s made. Separation of cyclohexane from the extract wa s easily accomplished due to the high va lat i1 i ty of th i s so lvent. A simple batch distillation apparatu s heated in a paraffin oi l bath was used for this separation . Partial vacuum of from 10 . 72 to 11.14 psia was applied to remove the last trace s of cyclohexane from the ~ extract . After removing the cyclohexane, a brown to black viscous product having the characteristic odor of shale oil wa s recovered . Removal of the high-boiling solvent, tetralin pOint=207-C) , proved to be somewhat more difficult. (normal boiling Vacuum distillation at approximately 6.86 psia was employed for this separation using a Vigreaux column with par ti al reflux. electri c hot plate with A paraffin oil bath heated by an an ilMlersed magnetic stirring bar provided energy to boil the extract. Boil i ng corrrnenced when the condensate temperat ure (measured at the top of the column) reached about 60·C. The di sti llation was allowed to proceed until a slightly yellowish color was 54 observed in the overhead liquid. The presence of an impurity in the tet ra 11 n the due discovered. to oxi dat i on of 50 lvent du ri ng stara ge was Since th is impurity was of sl ightly higher boiling point than tetra 1i 0, its presence compounded the diffi culty experi enced 1n achieving a good separation of solvent and extracted material. While chromatog raphic analysis of the distilled tetra1;n extracts showed that in no cases was tetralin remova l complete, an approximate value of the weight percent of solvent remaining in the extract could be determined gas by chromatography. By subtracting the carbon and hydrogen of the solvent from the total carbon and hydrogen found by elemental analysis and accounting for the weight of solvent, an estimate of the carbon , hydrogen, and nitrogen content in the tetralin extracts was made. Similarly, by ignoring chromatogram peaks attributable to the so lvent and i mpu rity. the boi 1i ng poi nt di st ri but i on of the extract itself was determined. < gram was facil i tated Elimination of solvent peaks from the chromatoby the high boiling nature of the extracted material -- no m3jor peaks were present in the vicinity of the tetralin peak. Removal complete; thus of cyclohexane from the extracts was assumed to be no correction was applied to results of analyses of cyclohexane extracts. 3.3.2 Simulated Disti llat ion Simulated distillat ion by gas chromatography was carried out on extracted material in order to determi ne the effect of processing conditions on the boiling point distri bution of the extracts. The boiling po i nt dis tribution is one criterion of the quality of a crude fuel and is roughly indicative of the amount of further processing 55 necessary to refine that crude fuel into a desired product such as gasoline or diesel fuel. The analysis was performed in accordance with ASTM (1973) standard chromatograph. 02887-73 This procedure usin g a Hewlett-Packard prescribes the 5830A use of gas temperature programming and a neutral sil icone gum-rubber liq uid phase to accomplish a low-resoluion separation of a mi xture of hydrocarbons according t o boiling point. reproduc;ble~ It is rapid (40 minutes), and requires only a small amount of samp le (1 microliter). Retention time is corre l ated to boiling point temperature by analyzing a standard mixture of n-alkanes whose boiling points are known (Table 3.3). of each A calibration curve obtained by plott ing the boiling point component of the sta nda rd illustra ted in Figure 3.7. versus its retention time is The assumption that individual components are eluted in boiling point order is not strictly true when the sample contains polar roolecules and aromatics (such as sha le oi1)~ since these components elute at a somewhat different time than the n-alkane with a correspond; ng normal bo i 1 i ng po i nt. Fortunately~ the use of a low resolution column has the effect of " smooth ing out II the se factors and allowing the retention time versus boiling point correlation derived from the chromatogram of confidence (Bu tler. 1979). the n-al kane standard to be with Resolution;s defined as follows: (3.1 ) RO = Resolution = In accordance with used the ASTM standard, resolution is required to between three and eight for n-hexadecane and n-octadecane. be Figure 3.B 56 rable 3.3 Composition of the n-Paraffin Calibration St andard With Normal Bo iling Points and Typical Retention Times of Components Carbon Number 5 6 7 8 9 10 11 12 14 15 16 17 18 20 24 28 32 36 40 Normal Bal l ing Point ( • C) 36. 1 69 .0 98.4 125.9 150.8 174.0 195.8 216.2 252 .5 270 . 5 287.5 303.0 317.0 344 391 432 468 498 525 Typical Retention Time (min.) 0.29 0.48 0.91 1. 73 2.93 4.45 5.81 7.59 10.09 11.17 12.51 13.47 14.28 16. 23 19 .51 22.33 24.79 26.95 28.87 57 5 00 400 u (!) w .:> , 3 00 ~ Z H 0 Cl. (!) z 200 H ...J H 0 m 100 OL-__- L____ o 5 ~ 10 ___ _ ' L __ __ L_ _ _ _ 15 20 ~ _ _~ 25 RETENTION TIME, MINUTES Figure 3.7 Calibration Curve for GC Simulated Disti l lation 30 58 2.. 33] ~ f...3.2 16. 5 nm 2B.53 nm RO • 2 X 16.5 • 5.6 2.7 + 3.2 ., !il3lft AREA :t n B.IB fIIREA .. ", II .•• LIH 29f.£B 1 .. 63 317geaBSB 2.13 24 . 33 47675H! 28.~J 1360'S 3 13?eSe 3e~'eBB XFI fIIREfill " 1I.IIBl 8.BS. D. Sl' '';''.'29 11.147 II.'" .... 41 l.tlSea E+ • Figure 3.8 Illustration of Calculation of Resolution for n-C 18 and n-C 16 Hydrocarbons Under Simulated Di st,11ation Condi tions 59 shows the pert; nent chromatogram and the ca 1cu l at; on of reso 1ut i on for the column and specific temperture program used, verifying that the resolution specification was met . Integration of peak s was performed electronically by the HewlettPackard 18850A GC terminal with respe ct to the true baseline. The accumulated area under the chromatogram was assumed to correspond to the amount of samp 1e wh i eh distillation. wou 1d be recovered in the overhead by bu 1k Implicit in this assumption is the supposition that the flame ionization detector responds equally to all components . While the FlO does re spond fairly uniformly to a variety of hydrocarbons. it is the low-resolution nature of the analys is which allows the assumption to be considered valid . In us ing a low-resolution co lumn in analyzing a complex material such as an oil shale extract, a number of components elute simultaneously , resulting in detection of "average" or typical components representative of the actual components of the sample . Choice of operating conditions, column length, and packing material seems to vary greatly among investigators except in selection of the detector, where the FID ;s preferred (Butler, 1979). of the oven temperature is required, Time-progranrning although the heating rate and beginning and final tempera tures vary somewhat. Any set of operating conditions that satisfies the requirements of the ASTM standard is acceptable. Table 3.4 lists the operating parameters and column materials used in this study. A Fortran computer program (see Appendix B) wa s written to reduce the output data retention time from of the chromatogram. each peak to boiling The pro gram converts point by a the cubic-spline 6D Ta ble 3.4 Operating Parameters for GC Simulated Distillation Column 3 1 x 1/8" sta i nless steel S% OV-I OI on 80/ 100 mesh Ch rornosorb PAW / DMCS FlO dete ctor Operati ng Parameters Init ia l temperat ure Fi na l t empe rature Heat; n9 rate In jection port temp erature Detector tempe rat ure Carrier fl ow Sample size (he l i um ) 3S0C 32SoC lOoC/mi n 222°C 32SoC 30 ml /mi n lu t 61 polynomial to the boiling point fit versus retention time relati on derived from the chromatogram of the n-paraffin standard. percent determined for each peak is taken as The area equivalent to weight percent. and a plot of boiling point versus cumulative weight percent recovered at a seri es of temperatures and/or di sti 11 at ; on temperature required for a given weight percent recovery may also be produced. 3.3.3 Carbon-13 Nuclear Magnetic Resonance Dried, ground spent shale samples from several constant -tempe rature runs and from a series of linear-heating runs were analyzed by carbon-13 nmr with cross-polarization and magic-angle spinning. Although carbon- 13 nmr has been used for some time to elucidate structural information . a difference in the general nature of solid materials had limited the applications of the method to liquids until the recent development of the techniques of cross -polarization and magic-angle spinning. Only in ~echnique been applied to such complex natural materials as coa l and oil Shale. The CP/MAS techniques are used the last few years has the to narrow the l i nes of carbon-13 nmr signals so that a greater amount of useful st ru ctu ral information may be obtained. Magic-angle interactions spinning is employed to e l iminate between BC and IH magnetiC dipoles. dipole-dipole In l iquids, the random "tumbling" motions of molecu les averages these interactions t o zero; however, since solid molecules have much less freedom of ' movement. dipole-dip ole observed. interactions which result in line broadening are The energy of interactio n of th e two magnetic dipoles shown schematically in Figure 3.9a oriented at an ang le e to a strong external magnetic field is given by the expression: 62 (3.2) By rotat; ng the sample about an axis oriented at the magi c angle. Om ' with respect to the external field (Figure 3. 9b), the dipole dipole energy of interaction can be made to disappear. the also term 1-3c05 20 vanishes. results in the giving e elimination effect ive ly averaging orientational m = of 54 . 70 . This occurs when Magic -angle chemical-shift spinning anisotropy by variartions of resonance frequency for a given type of carbon atom. The techn; que of cross - po 1a r; zat ion. developed by Pi nes et a1 • (1973). circumvents the problem of long spin - lattice relaxation times in solids. In this technique, two rad io -frequency signals, one at the IH resonant frequency and one at the 13C resonant frequency. are applied with intensities as given by the Hartman-Hahn condition (1962). Under this condition, an effi cient transfer of net magnetization occurs from IH spins to Be sp ins which is II1.Jch faster than the l3e rela xation . By properly timing application of the l3e irradiation field and repeating the process a number of times, the carbon-13 nmr spectrum is obtained by Fourier transform of the time-averaged free induction decay of the transverse 13e nagnetization. A remaining source of line-broa de ning not removed by the ePjMAS methods is that due to dispersion of chemical shifts of a given class of carbon atoms due to small differences in the structural environment of individual atoms be cause of the comp l exity of the molecu l e. An example of this is the variety of chemically di fferent rrethylene groups expected in kerogen, each contributing a signal in the "methyl region" (centered 63 Ho H r / / C Instantane o~s Figure 3.9a Oipole-Dipole Interaction Between aPairof1C and IH Nuclear Magnetic Moments Ho 9. "" H c Figure 3.9b The Effect on a Particular Pair of 13C and 1H Nuclei of Rapid Spinning of the Sample Containing them about an axis oriented at the Magic Angle Relative to the Static Magnetic Field, HO. Showing the Instantaneous (r) and Average (rav) Internuclear Vectors. (after Bartuska et al .• 1977) 64 at 28 to 30 ppm from TMS) but with a slightly different chemical shift depending on nearby structural features. The result is an lIenvelope" of methyl resonances in the spectrum. For more complete details of the underlying theory of crosspolarizat i on and magic-angle spi nning. the interested reader is referred to the work. of Pines et al. (1973) as well as that of Kesserneier and Norberg (1967) . As an analytical technique, carbon-13 nmr with CP/MAS enables quant1tation of the relative amounts of aromatic and aliphatic carbon in a solid sample. which allows a value of aromaticity (defined as the weight fraction of tota l carbon that is aromatic) to be calculated. AromaticHy values are useful in predicting the extent of conversion of kerogen to 011 by retorting and in following changes in carbon-type distribution with the extent of retorting. have reported that the aromatic carbon Mikni s et a1. (1980, 1982) in raw oil unconverted during ind i rect (noncombustion) retorting. shale remained Good agreement was found between the amount of aromatic carbon present in the raw shale and the amount of carbonaceous residue on the spent shale, which was found to have an aromaticity of 1.00. This correlation between raw shale aromatic carbon and spent shale char was based on carbon-13 nmr measurements of raw, partially retorted, and fully retorted 011 shale and was found to hold for 011 shales of differing grades, geographic locations, and geologic ages and formations. Based on this finding , Fausett and Miknis (1981) described a kinetic roode1 by which aliphatic portions of kerogen decomposed to oil and gas with subsequent coking of some of the 011, and aromatic portions remained unconverted as residual 65 carbon. A fault of this roode l is that it does not predict th e presence of aromatics in the shale oil . I n th e present study . ca rbon -1 3 nmr was emp 1oyed wi th CP /MAS t o determine i f the thermal solution process is mo re effective than pyrolytic reto rtin g rrethods in removing aromatic carbon from the shale and t o ascertain whethe r a dif fer e nce in the ability of cyclohexane and tetral;n to remove ar omati cs is obse r ved. The r e l event i nstrument conditions used in obtai ni ng the spectra are given ;n Tab l e 3 . 5. 66 Table 3.5 Instrument Conditions used in Carbon-I3 nmr with CP/MAS Spectrometer frequency 25.150 MHz Spectral width 20000 Hz(795 ppm) Total number of data points 800 Number of transients recorded 10000 90·C pulse width 4. 850 Contact time for CP 1. 50 ms Repitition time 0.40 s Spin frequen cy "s -4.1 kHz CHAPTER 4 RESULTS In this chapter, experimenta l and analytical results are presented Section 4.1 covers the effect of the solvent/shale and di scussed. ratio. particle size. solvent. and shale organic content on the yields obtainable in 24-hour. constant-temperature runs. Section 4.2 discusses the results of elemental analysis (for carbon, hydrogen, and nitrogen) and carbon-13 nmr analysis of the organic portion of spent shales and the influence of extraction temperature and solvent on the HIe and N/C atomic ratios and the aromaticity . GC simulated material. distillation Section 4.3 reports the results of e 1ementa 1 and ana 1ys is of ext racted Finally. 1n Section 4.4 the kinetic analys is is presented. , 4.1 . Yield Studies The initial phase of this work. focused on determination of thermal solution yield using cyclohexane . During the early stages project. the several modifications of experimental of the procedure were adapted with the intention of el imi nating possible sources of errore Cyclohexane proved to be a relatively easy solvent to work. with, consequently. the procedure was "ironed-out" using cyclohexa.ne as the extracting solvent. in the study. previously Additional solvents were selected at a later time The other pure solvent used. tetralin, has been used in coal extractions. for which it is ideally suited due to 68 its abi lity to transfer or "donate" some of its hydrogen atoms to a hydrogen-deficient solute, ske 1etan of coa 1 • Although the kerogen of Green River oil shale is of relatively low such as aromaticity, the the highly aromatic hydrocarbon possible real i zation of greater extraction yields using a hydrogen-donor solvent was deemed worthy of investigation. The th i rd solvent, creosote 011, is a complex coal- derived liquid cons i sting largely of phenolic compounds. It was chosen for study since it is anticipated that any scale-up of the thermal solution process would likely necess i tate use of such a solvent which i s less e xpensive than a pure solvent and for which comp lete recovery was not necessary. Within the range of temperatures that the study encompassed, cyclohexane was always i n the supercrit i cal state (the temperature of the extraction was above the cr~t ic al tempe rature of the solvent. 28DOC) and tetralin was subcritical, making tetralin runs primarily liquid phase extractions. (Although- vapor phase tetralin would also exist. there would be little contact between va po r and solid shale. The low density of the vapor limits i ts ability to act as a solvent for the large molecules supercrit i ca 1 present solvent as extracti ng organi c mater; al temperature used in the in kerogen.) compared to The effectiveness a l i qu i d phase caul d thereby be assessed. constant-temperature runs of solvent a at The hi ghest (382°C) is considerably lower than that at which most retorts operate (generally 47S'C and higher). As po i nted out by Larson and Wen (1981), the high operating temp erature of oil shale retorting processes is a significant drawback to efficient energy recovery from oil shale in the form of liquid fuels due to thermodynami c constraints. 69 Three blocks of shale of differing den sity, thus organic content, were initially chosen for experimental runs. Only a small block. of very rich (62 gal / ton) shale was available; conseque nt ly, a different sampl e of r ich shale of 50 gallon-per-ton assay was obtained for tetral;n and creosote 011 runs. The sha 1e samples used va ri ed from 17 to 62 9a 11 cns per ton (11.3 to 37.9 weight percent organic). with organic content could thus be determined. Any variation in yield Thompson and Pri en (1958) found that yield varied inversely with shale organic content at 200 0 and 300°C. but was essentially independent of organic content at 40QoC for tetral;n extractions of Green River oil shale. Summation of raw data for all thermal solution runs is tabulated in Appendix C. 4.1.1 Effect of Solvent/Sha le Ratio The amount of oil shale and solvent used in experimental runs was normally held constant at 70 grams of shale and 500 milliliters of solvent. In order to determine the variation of yield with the relative amounts of solvent and shale, a series of runs in tetralin was made in which th e amount of solvent was varied, holding the weight of 50 gallonper-ton shale constant at 70 grams. in each run. A temperature of 342°t3°C was used For a solvent density of 0.973 grams per milliliter, the yield is plo tted for runs made at several solvent-to-shale weight ratios in Figure 4.1. 6.95, wh ich is Experimental runs were rrade at a ratio of approximately above the range of ratios in wh i ch the yield was affected, thereby ensuring that an excess of solvent was present. having excess solvent, the yield was 8y not limited by mass transfer reSistance at the shale-solvent interface. 70 1eer---------------------------~ Figure 4 . 1 Yield vs. Solvent/Shale Ratio In Tetralin, · 350' ±3'C . 71 4.1.2 Effect of Particle Size It was also desired to determine the extent of influence of particle size on the yield, if any. Three ranges of particle sizes were avalable: fine (-28 mesh). medium (-8+28 mesh). and coarse (+8 mesh). It was assumed that the organic content of the shale was independent of the particle size. NO attempt was made to divide the sample into narrower size ranges. were used. used. 8 Shale E and a constant temperature of 357 t2·C Tetra'in was the solvent and a 4:1 solvent/shale ratio was The results of the runs were inconclusive -- the highest yield was obtained for the medium size particles (84.2 percent) and the lowest for the fine particles (72.2 percent). particles was 81.3 percent. The yield for the coarse In analyzing these results, it should be ment i oned th at the reproduc i bi 1 i ty of y; e 1d data ; s expected t o be no better than t5 percent, which places the highest and lowest yields just outside the range of experimental uncertainty. Taking into account the wide variation of particle size within the three groupings, it is not surprising that any actual variation of yield with particle size could be masked. Haddadin (1980). in studying the effect of particles from 50 to 300 mesh found that particle size variation had a Significant effect on the tetral in extraction yield in the size range of from 150 to 225 mesh. Outside this size range, the yield was roughly independent of particle size. 4.1.3 Effect of Solvent and Shale Organic Content Figure 4.2 shows the experimental yield from constant-temperature runs made with supercritical cyclohexane for three shales of varying organic content: 11.3, 19.7, and 39.7 percent by weight (shales A, B, .' CI w 100 > 0 ~ w 80 ~ u 60 H Z <{ (!) ~ 0 ~ , CI ....J W H >- 40 ~ /' / o 20f- D SHALE B (35 GPT) ~ 0 260 SHALE A (17 GPT) V SHALE C (62 GPT) 280 300 320 340 360 380 400 EXTRACTION TEMPERATURE, DEG . C Figure 4.2 Yield vs . Temperature in Cyclohexane " N 73 and C, respectively). At higher temperatures, the yield is seen to be independent of organic content and is as high as 90 percent (based on At lower temperatures, il11Tledi ate ly evi dent ad 91 na 1 organi c present). is the significantly lower yield observed from the 35 gallon-per-ton samp 1e (sha 1e B) than that from the other two samp 1es • That the yi e 1 d from the medium grade shale is so much lower than that of the other two samples suggests that some characteristic of this shale is restricting the amount of organic which can be extracted from it. lower yields from this shale were also observed in tetral;n extractions and a possible explanation for this is di scussed in more detail later. Regarding the other two samples, slightly higher yields were obtained from the rich shale (shale C) than contradictory to the tetralin. from the findings lean of shale Thompson (shale and Prien A), which (1958) is with This observation suggests that. on the average. organic- inorganic bonds may be less susceptible to supercritical solvent action than bonds within the kerogen. since more organic-inorganic bonds must exist in the lean Shale. Also worthy of mention is the slight decrease in yield observed at 382 °C extraction temperature for the rich shale. The presence of a broad maximum in yield between 350° and 375°C is thus suggested. Deposition of insoluble higher molecular weight components created by polymerization occuring after extraction ITDst likely is the cause of the reduction in yield. Any insoluble material present on the shale is rreasured as unconverted organic in the oxidation step of the experime ntal procedure. No such maximum was observed for either of the other samples. implying that dilution of extracted material may reduce the extent of po lymeri zat ion. 74 Results of tetral1n e xtractions are surrmarized in Figure 4.3. Aga1n, three grades of shale were used, the same 17 and 3S gallon-per- ton shales (shales A and B) as were used i n cyclohexane extractions, and a SO gallon-per-ton shale (shale 0). The yield, as noted in cyclohexane runs. seems to be nea r 1y 1ndependent of organ; c content at 37 SoC. The yields for the rich and lean shales are nearly superimposed over the entire temperature range studied; however, the 35 gallon-per-ton shale is again observed to be less susceptible to solvent action than the other two samples; significantly lower yields medium grade shale. are observed for the No maxilTlJrn yield is observed with any of these shales as was observed for the rich shale cyclohexane extracts. This absence of any maximum may be attributed to the hydrogen-donor ability of tetral i n; any free radicals formed by bond ru pt ure may be termi nated by add ition of hydrogen from the solvent. A difference in the temperature dependence of the yield for cyclohexane and tetralin extractions of the rich and lean shales is observed in Figures 4.4 and 4.5, which show that the supercritical solvent removes temperatures more (T<365°C). organic matter from these shales at low With increasing temperature, the yield from cyclohe xa ne extractions rises fairly rapidly then levels off at about 350°C, wh i le the tetralin extraction yield shows essentially a linear increase. Since the temperature dependence of the yield is different for the two solvents, a difference in the mechanism of removal of organi c material, due to a basic difference in the physical state of the solvent at the temperatu res of the study, is postu 1ated. Sped fi ca 11y. this difference is that cyclohexane exists in the supercrit1cal fluid c w 100 > 0 L w 80 ~ u 60 H Z « (!) ~ 0 40 o ~ , C -l W H >- 20 SHALE A ct7 GPT) D SHALE B (35 GPT) V SHALE D (50 GPT) 0 260 280 300 320 340 360 380 EXTRACTION TEMPERATURE, DEG. C Figure 4.3 Yield YS. Temperature In Tetralln 400 C\ w 100 > 0 ~ w 80 H 60 a::: u Z <t: t') a::: 0 40 t:. ~ , 0 CYCLOHEXANE 20 C\ t:. TETRA LIN ..J W H ~ 0 260 280 300 320 340 360 380 400 EXTRACTION TEMPERATURE, DEG . C Figure 4.4 Yield vs. Temperature for Rich Grade Shales In Cyclohexane (Shale C) and Tetralln (Shale D) ~ 100r·------------------------------------------~ o (j 80 ~ U H 60 ~ 40 z « (!) ~ , C ....J W H >- o 20 CYCLOHEXANE A TETRAL:IN O. 260 , 280 300 320 340 360 380 400 EXTRACTION TEMPERATURE, DEG. C Figure 4.5 Yield vs. Temperature for Lean Grade Shale (Shale A) in Cyclohexane and Tetralin ~ ~ 78 state, while the tetral1n is present as an equl1ibr1um mixture of liquid and vapor. Use of supercritical fluids has recently been studied as a !Teans of recover1ng organics from coal (Whitehead and W111iams, 1975; Slomk.a and Rutkowski, 1982; Bartle et a1., 1982; Kershaw and Jezko, 19B2) and wood (Cal1ml1 and supercritical 01cay, 1982). extraction little of oil attention shale kerogen, has been given to although Martin and Williams were granted a patent in 1977 for a kerogen extraction process using supercr~t1cal toluene at 440°C and 10 MPa pressure. A yield of 88 percent kerogen removal was reported in this process. The supererit 1 ca 1 ext raet ion techn1 que is an effect 1 ve weans of -extracting organic material of low volatility since the solubility of a low-volatile solute in a supercr1t1 cal fluid is enhanced greatly (up to 1000 times accord~ng to Whitehead and Williams, 1975) above that which would be predicted from Dalton's Law of Part1al Pressures Wise, 1971). (Paul and Supercritical fluids posess add1tional properties which make them ideally suited for extraction of nonporous solids; namely, their low (Wi 11 1ams • viscosity and high 1981) • Under d1ffusivity suffi c1 ent as compared pressu re. the to liquids dens 1ty of supercr1tical fluids is similar to that of liquids. which imparts to the supercr1t1 cal fluid sufficient capacity to act as a solvent for orgnaic molecules of moderate molecular weight. Theoretical models have been developed Vezzetl, (Johnston and Eckert, 1981; 19B2) which allow prediction of the solubility of solids in supercritical fluids; however, these roodels are of little value for complex materials such as coal and oil Shale for wh i ch determination of the thermodynamic properties necessary for the appl i cati on of the roodel is not presently possible. ~ 79 Theoret ica l conside rat ions show that the solubi l1ty of a solute in a supercrit ical fluid increases with the flu id density, wh ich implies that an ext raet 1on temperatu re nea r the erit i ca 1 temperatu re shou 1d be employed for maximum solubility. In a closed vessel, however. the pressure and thus the density of the solvent increase with temperature, so that higher temperatures should result in enhanced yields due to both greater decomposition of kerogen result i ng from the increased thermal energy available for bond-breaking as well as the greater capacity of the flu id for solute JrOlecules beclliuse of its increased density at highe r pressure . Higher yield was observed, as expected, with cyclo- hexane extractions, as mentioned previously. The pressure in the vessel was not controlled. it was simply the autogenous pressure generated upon heating. The extractions thus dependence of yield versus reflects the yield. temperatu re the combined whereas the trends for cyclohexane pressure and temperature yield trends for tetralin extractions represent only· the temperature dependence, since pressure variation has a negligible effect on the density of the liquid phase tetralin . From the experimental results, it can be proposed that the temperature dependence of the yield is approximately linear (tetralin results), whi ch su ggests that the pressure dependence (whi ch is superimposed on the temperature dependence in cyclohexane extractions) is curvilinear. These arguments assume that the yield is not affected by the chemical nature of the solvent. Chemical properties have been shown to significantly affect the yield at 200·C (Schnackenberg and Prien. 1953); solvent has however, little it appears influe nce on that the chemical the yield at nature of the higher temperatures 80 (O'yakova. 1944; Jensen et al., 1953). Researchers have used a variety of solvents in thermal solution studies and obtained simi lar yields with different solvents ; the chemical nature of the solvent lTk1y therefore be considered i nsignificant at temperatures in the range of from 300 0 to 400'C. The preceding qualitat i ve discussion of yield dependence does not apply to the 35 gallon-per-ton shale. This shale gave considerably lower extraction yields than the other samples except at about 375°C; however. Figure 4.6 illustrates that the yield from this shale was essentially independent of the solvent temperature range studied. It is therefore some character of the shale, rather than of the solvent, material removed. A mass used throughout the entire which restri cts the amount of organic transfer limitation within the shale is postulated as limiting the yield from th i s shale sample. Such a mass transfer limi tation could result from a lower natural porosity. As more organic matter is removed (at higher temperatures). the porosity of the shale increases, thereby increasing the available void volume through which transfer of soluble organic material may proceed to the bulk solvent. A mechanism by which the porosity increases as organic matter is removed thus allowi ng IOOre organic to leave the shale matrix, which in turn increases the porosity, and so on, is postulated. While this "positive feedback" mechan i sm no doubt takes place in the other shale samples. the effect 1s much more noticeable in the 35 gallon-per-ton shale. The rapid increase in yield from this shale with increasing temperature is a result of this mechanism. This suggests that the natural porosity of raw shale B was considerably lower than that of the a w 100 > 0 L W 6 80l 0 ~ U H 60 60 0 Z In <t: (!) ~ 0 o~ 40 6 ~ a , -l W H r o 20 CYCLOHEXANE 6 TETRALJ:N 01 260 I I I I I I 280 300 320 340 360 380 EXTRACTION TEMPERATURE, DEG . 400 C Figure 4.6 Yield vs . Temperatu re for Medium Grade Shal e (Shal e B) in Cyclohexane and Tetralin ex> 82 other samples, low enough that no higher yield was observed using the supercritical solvent despite its enhanced ability to penetrate into a nonporous solute. The observation that a sample of oil shale from a particular deposit yields less of its organic material in therma l solution than other samples from the same deposit is deemed to be significant. apparent in the results obtained from different is that a greater variation in the yield shale samples was observed in cyclohexane extractions than in those made with tetral;n as the solvent. observed in this work Also Yields are generally comparable to those found by previous researchers in thermal solution. Runs made with creosote oil as the sol vent were limited to the 50 gallon-per-ton shale. very hi gh temperature. yi e 1d of Interestingl y . as is evident i n Figure 4.7, a 96 percent A lower yield was was observed observed at at 350°C 375°C. extraction indicating the existence of a maximum in the yield versus temperature relation. This maximum occurs at a somewhat lower temperature and is more pronounced than that observed in cyclohexane extractions of rich shale. ind icating that the solvent itself may partially decompose unde r the extraction conditions and participate in polymerizat io n react ions which result in coke deposition on the shale. was noticed on the spent The characteristic odor of the solvent shale after Soxhlet extraction. further evidence that the creosote 011 had reacted with the shale resulting in the deposit ion of insoluble solvent-derived material on the spent shale. No other analyses of creosote oil extracts of spent shale were performed. These runs were carr ied out with the intention of c ~ o 100 :I: 80 w ~ ~ I v ~ U H v 60 Z <t (!) ~ o 40 ~ , 20 V SHALE 0 (SO GPT) C ...J W H >- O. 260 I 280 300 320 340 360 380 400 EXTRACTION TEMPERATURE, DEGo C Ffgure 4 07 Yfe1d VSo Temperature fn Creosote Of1 (Shale 0) en w 84 determining the suitability of a complex, fossil-fuel-derived solvent for extract ion of organics from oil shale. D'yakova (1944). whose study of thermal solution included a coal-derived l iqui d (anthracene oil). found it to be the most satisfactory solvent used 1n semi-continuous operation. Jensen et al. (1953) also used anthracene oil as well as petroleum kerosene and shale 011 fra ctions an solvents in batch thermal solution and observed a maximum yield of from 85 to 90 percent organic remova l in the temperature range 410 0 to 440°C with these solvents. The temperatu re at whi ch the maxi mum yi e 1d recorded with pet ro 1eum kerosene occurred was shifted to lower temperature as the increased; the longest exposure time was 180 minutes. exposure time At this exposure time. the maximum yield was found at about 390°C. The re sults of the present work with creosote oil as an extracting solvent, as well as the previous works of D'yakova (1944). Jensen et al. (1953). Hsiao (1978). and Thorum (1979) . show that crude solvents derived from fossil fuels are as effective in thermal solution as pure solvents in terms of yield of organic material from oil shale. An important consideration in using such solvents is the possibility of solvent decomposition resulting in an undesirable loss of liquid material in the process. That the highest yield obtained in any creosote oil at 350°C is noteworthy. run was observed with This result suggests that phenolic compounds are effective at solvating the organic matter in oil shale. A similar observation was noted by Kin9 and Stock (1982) in study i ng coal dissolution. enhanced the They found that, at 350° and 400°C, the presence of phenol rate of decompositi on of four nHrogen-contai n1 ng 85 compounds. They concluded that phenols enhanced thermal dissolution of , coal via their catalytic influence on cleavage of C-O and C-N bonds. Such bonds are a 1so present in the organ; c rmteri ali n 011 sha 1e, so it seems logical to as sume that phenols could act siml1arly in kerogen decomposition. 4.2 Spent Shale Organic Residue Analysis In this section, the results of elemental analysis and carbon-I3 nmr analysis of spent shales is reported and discussed. The nature of the spent sha 1e 1s an ; mportant cons i de rat ion in process des i gn and has been neglected in many previous reports on thermal solution. Several chemical properties of the spent shale were determined in this work. Addit iona l characterization of the physical properties and more detailed composit i onal analysis of the spent shale from thermal solution is needed. 4.2.1. Elemental Analysis Elemental analysis for carbon, hydrogen, and nitrogen was performed on spent sha 1e res i dues to determi ne the e 1ementa 1 compos it i on of the insoluble organic matter. in a Perkin-Elmer composition Model Finely ground samples were combusted at 450°C 2406 elemental of the organic material analyzer to determine (Heistand and Humphries, the 1976). This technique was judged to be superior to that of analyzing acidwashed (carbonate-free) samples. Results presented in thiS section lnclude the hydroge n-to-carbon (H / C) and nitrogen-to-carbon (N/C) atomlc ratios. The complete results of the analyses are presented in Appendix 86 4.2.1.1 Residues of cyc lohexan e extractions. In Figure 4. 8 are presented the Hie ratios of residues from cyclohexane extractions of For each sha le samp le, the re sidue HIe ratio wa s shales A9 B. and C. similar to that temperatures . of the In general, extraction t emperature port ions of kerogen preferentially original a trend increases wi th removed at higher higher kerogen toward low extraction HIe ratio as decrea si ng is observed, whi ch indicates that HIe rati os temperatures portions are relatively resistant to so lution. ratio at (more saturated) whi le the aromatic The decrease in Hie is most pronounced for the rich shale (shale C) pronounced for the lean shale (shale A). are and l east A possible explanation for this observation is that the rich shale kerogen may contain a greater proportion of hydrogen-rich, solvent-susceptible side chains and bridges between po l ycyc 1i c centers than the 1eaner samp 1es. Deposition of carbon-rich molecules on the spent shales from high-temperature ri chshale extracts may also contribute to the low H/C ratios «1 .0 ) observed for these samples . larson and Wen (1981) observed a similar trend in res idue H/C ra t i os in a ser ies of experiments conducted to study l owtemperature (300·-42S-C) conversion of a 49 gall on-per-ton Piceance Basin shale . An increase in N/C ratio with increa sing extraction temperature was Observed with each sha le, as illustrated in Figure 4.9. For each shale sample, the N/C ratio at low extraction temperatures was lower than that of the raw shale kerogen, but increased to a value consi derably greater than that of the kerogen at high extract ion temperatures. concluded then that nitrogen-containing fragment s of It can be kerogen are 1.8 0 H ..... < ~ 1 .6 1 .4 •• \V U "I w ::J a H (f) w ~ 0 00 V V KEROGEN 00 00 1.2r 1.0~ 0 0.8~ V V 0.61 275 1 1 1 1 300 325 350 375 EXTRACTION TEMPERATURE, DEG. 400 C Figure 4.8 Hydrogen-to-Carbon Atomic Ratio of Residual Organic Material. Solvent: Cyclonex,ne OSh,l. A OSh,1.8 V'Sh,l. C co " 4.0 1"\ 0 0 3.51- v 3.0 -* U ....... z V V 2.5 W ::J 0 H 2.0 (f) w a::: V 1.5 / KEROGEN ~ • I. 01 275 [] V [] 0 [] V [] 0 [] 0 1 300 1 325 1 350 1 375 400 EXTRACTION TEMPERATURE, DEG. C Figure 4.9 Nitrogen-to-Carbon Atomic Ratio of Residual Organic Material. Solvent : Cyclohexane OShal. A OShal. B <;7Shal. C &l 89 considerably less susceptible to solution than hydrocarbon fragments and that the residue contains a much greater proportion of nitrogen- containing structures than kerogen. kerogen nitrogen occurs in This re su lt is as expected, since stable heterocyclic molecules porphyrins (larson and Wen, 1981) and pyrroles (Yen, 1976). residue N/C ratios than those of the kerogen of each such as Th at l ower sample were observed at low extraction temperatures was unexpected. and suggests that some nitrogen exists in easily solubilized fragments having hi gher N/C ratios than that of kerogen or possibly in naturally occurring bitumen. 4. 2.1. 2 Residues of tetra'," extractions . The HIe rat i as of the organic re sid ues from tetralin extractions are illustrated in Figure 4.10 for varying constant extraction temperatures and in Figure 4.11 for residues from linear-heating runs. It is apparent that the Hie ratios increase with increasing extraction temperature for the lean and rich shales in contrast with the decrease in HIe ratio observed in cyc l ohexane extraction residues. A slight decrease in the HIe ratio of the residue from extractions of the medium grade shale at higher temperatures was observed. The difference ;n the trend in residue H/C ratio with temperature of the medium 9rade sha le ' (shale B) as opposed to the rich (sha le 0) and lean (shale A) grade shales is noteworthy and implies that a different mechanism may be acting in extraction of organic matter from the medium grade shale. A similar suggestion was previously made in observing the yield versus temperature data. Preferenti al extraction of low H/C portions of the kerogen of the rich and lean shales may take place at ..' 2. 0 H t- 2.0 0::: I .9L... u I .8 ~ "w:r:: ::J Q H (/) W 0::: "Y 2. I ~ I .7 I .6 0 0 / ... I .5 "Y 0 "Y 0 "Y "Y 0 "Y cP 0 0 0 I .4 I .3 275 300 325 350 400 375 EXTRACTION TEMPERATURE, DEG. C Figure 4. 10 Hydrogen-to-Carbon Atomic Ratio of Residual Organic Material. Solvent : Tetralin OShale A OShale 8 <;7Shale D l'l 1.7 t- 0 H l- <{ I .6 KEROGEN 0 I 0::: u "J: (/) w o 0 I .5 0 w :J 0 H 0 0 0 o 0 0 0 0 DO 0 0 0 I .4t- 0::: 1.3[ 275 I I I I 300 325 350 375 MAX. TEMPERATURE OF RUN, DEG. 400 C Figure 4. 11 Hydrogen-to-Carbon Atomi c Ratios of Residual Organic Material Linea r-Heating Runs. Solvent: r etra lin f~ -'" 92 higher temperatures, lea ving behind an organic res idue of high HIe ratio -- the residues. opposite of what was observed wi,th cyclohexane extraction Possible hydrogenation of kerogen fragments due to hydrogen transfer from the solvent. aided by the long residence time of the process, may also contribute to the increased HIe ratios observed at higher temperatures. From the observed residue HIe ratio from tetralin and cyclohexane extractions, it can be said that the 5upercritical solvent leaves behind a different type of organic residue than tetral;n. Significant differences in the HIe ratios of the organic residues after extraction indicate the need f or ITl)re detailed study of the residues in order to determine the most suitable method by wh ich the spent shale from a thermal solution environmentally process harmful should compounds be in disposed. the The res idue, as types well as of the physical characteristics of the residue, are expected to be considerably different than those of the spent shale from py r olyt ic retort i ng. The HIe rat ios of residues from linear-heating runs in tetralin, as seen in Fi gu re 4.11, temperature. are re lat i ve ly i ndependent of the maxi mum run In these runs, the constant H/C ratio indicates that both aromatic and aliphatic structures are being removed equally, regardless of temperature. Since the sample was exposed to a temperature ramp, the residence time at temperatures sufficient for hydrogen transfer from the solvent to occur (>...350 0C) 1s Truch shorter than for high-temperature, constant-temperature runs, which ·decreases OCcurrence of hydrogen transfer. the Benjamin et a1. likel1hood of the (1979) found that tetralin decomposed to the extent of only one percent in 18 hours at 93 400·C. Their experiments, however, were performed in argon an atmosphere wi t h no other material , such as oil shale, present . Certain component s of coal have been shown to acce lerate hydrogen transfer from tetral;n t o an acceptor compo und (King and Stock , 1982), and minera l matter cata l ysis has been suggested as playing an importa nt ro l e in hydrogen 1981) . tran sfer rea ctions during coal liquefaction (Whitehurst, Similar effects co uld be expected of the organic and inorganic components of oil shale in enhant:ing hydrogen tran sfer from tetra l ;n at temperatures below 400·C . Figure 4. 12 shows the N/C ratios for residue s from constant temperature tetra';n extractions . Identification of trends in this figure is diffi cult and the accuracy of the rather high values of the ratio for rich and lean s hale residues at about 375·C i s suspect due to the low concentrat ion of organic material in the res idue. It appears , however, that with increasing temperature, the N/C ratio of the rich shale (shale 0) re sidue stays constant, that of the lean shale (sha l e A) re s idue increases slightly, and that of the medium grade shale (sha l e B) decreases s 1i ght 1y . The absence of a di s tinct cons i s tent trend in residue N/C ratio with extraction temperature makes interpretation of these re s ul t s chemistry of difficu l t. the nitrogen The best compounds that can be said is complex and is that may depend variab l es other than temperature and organic content of the sha l e . the on A similar conclusion is reached regarding the N/C ratios of residues from linear.heating runs in tetral;n , illus tra ted 350·C, the ratio stays relatively con sta nt. there i s co nsi derable scatter in the data, in Figure 4.13. Below At higher temperatures, due in par t to the l ow 4.5 A 0 0 - ;I( v u "z w 3.5 3.0 2.5 :J 0 H 2.0 (f) w ~ o 4.0 1 .5 0 KEROGEN /TV 0 [J Y, V [J [J V 0 V [J ______ ______ ______ ______ ____ 275 300 325 350 375 400 1.0~1 ~ ~ ~ ~ ~ EXTRACTION TEMPERATURE, DEG. C Figure 4.12 Nitrogen-to-Carbon Atomic Ratios of Residual OrganiC Material. Solvent: Tetralin OShale A OShale B 'VShale 0 ~ , .1" 3.00 A 0 0 * 2. 50 t- U 2.25~ v 'Z W ~ 0 KEROGEN o 0 0 0 0 0 0 0 0 H w 0 2.00 Q C/) 0 0 2.75l 0 I. 75 ~ I .501 275 I I I I 300 325 350 375 0 MAX. TEMPERATURE OF RUN, DEG. 400 C Figure 4.13 Nitrogen-to-Carbon Atomic Ratios of Residual Organic Material from Linear-Heating Runs. Solvent : Tetralin '" ~ 96 concentration of organic matter in the residue. making accurate nitrogen determination difficult. Measured nitrogen concentrations for these high-temperature runs were typically on the order of 0. 05 percent . 4.2.2 Carbon-13 nmr with CP/MAS The technique of carbon-13 nuclear magnetic resonance using crosspolarization and magic -an gle (sect ion 3.3.3). As spinning an analytical has tool, been discussed previously carbon-13 nmr with CP/MAS allows quantification of the relative amounts of aromatic and aliphatic carbon present in an organic solid. Primarily the organ ic carbons are detected since a hydrogen atom must be sufficiently close ( .... 0.35 nm according to Miknis et po larizat ; on of that a1 •• 1982 ) to a ca rbon atom for In 011 ca rbon atom to occu r. cross - shale however, inorgan ic carbon exists in mineral carbonates wh ich , due to the intimate bonding of the organic and inorganic portions of the shale, may be cross -pol ari zed by adjace nt hydrogens. The contr1 but i on of the mi neral carbon to the integrated signa l intensity is small and may be subtracted from the total aromaticity," aromatic. integral or the to fraction allow of calculation total organic of the carbon "apparent which is Since, at present. re so lution is not sufficient to permit detailed stru ct ural elucidation, determination of aromaticity is the primary application of carbon-13 nmr to solid fuels. 4.2.2.1 Application to oil sha l e pyrolysis . Mik.nis and Maciel (1981) have performed carbon-13 analysis on several raw and spent oil shale sa mp les. In analyzing a number of samples of differing aromaticity from Colorado, Michigan, Kentuck.y, and Morocco. they have shown that the amount of carbon residu e remaining on the spent shales 97 after 1ndi rect (noncombusti on) retort; n9 correl ates well to the amount of aromatic carhon in the raw shale as determined by carbon-I3 nmr with CP/MAS. This correlation is shown in Figure 4.14. For a 30 gal/ton Colorado shale. the amount of aromatic carbon present was found to remain relatively constant during retorting. as shown in Figure 4.15. It was therefore concluded that the res idual carbon present after retorting originated material. The increasing retorting in the increase in aromatic fraction aromaticity of the temperature to a illustrated by the spectra in Figure 4.16. value of the spent starting shale with approaching 1.0 is In these spectra, the peak on the left (centered at about 128 ppm from 11-\5) represents aromatic carbons, whl1e the peak on the right (centered at 28-30 ppm) represents al iphatic carbons. Integration gives the area under each pea k, then the determ~ned aromaticity is by the total area. by dividing the area under the aromatic peak Based on the finding that essentially a constant amount of aromatic carbon remains in the shale during retorting, Fausett and Miknis (1981) proposed a kinetic model for kerogen decomposition in which volatile products (oil and gas) are formed most ly from aliphatic portions of kerogen, while aromatic portions of kerogen are converted to carbon residue. 4.2.2.2 Analysis of spent shales from constant-temperatu re runs. While the findings of Miknis and Maciel (1981) were intriguing , they did not seem to agree with qualitative observations of spent shale from the thermal solution process. In particular, little or no coke or residual carbon was observed on spent shales after extraction, and the high yields of organic material occurr1 ng. Preliminary indicated that carbon-13 nmr removal of aromatics was analyses of spent shales from 98 8 Kentucky-Sudbury KentuckyNew Albany D Morocco Michigan Colorado u u -... Colorado .... ~ 2 a ~ ____ a ~ ______ 2 ~ ______- L_ _ _ _ _ _ 4 ~ 6 8 Aromatic Carbon in Raw Shale. 9 Figure 4.14 Pl ot of Aromatic Carbon in Spent Shale vs. Aromatic Carbon in Raw Shale f or Different Oil Shales. Miknis et al •• 1982. Ada pted from Fuel , vol. 61. 9 8 .. 7 ';6 " u -5 --:<:3 u4 . a--- ...0.. - - U- - - ..n LI- D ~2 1 a t a t I 100 '. 200 300 400 Temperature. °C 500 600 Figure 4. 15 Pl ot of Aromatic Carbon vs. Retorting Temperature for a 30 gal/ton Colorado Shale. Miknis et al . • 1982. vol. 61. Adapted from Fuel. 99 250 °C t I I , I I 280 240 200 I I 160 I I I I 120 .0 ppln frl>ln TM5 I I "0 I I 0 1 _"0 I Figure 4.16 Carbon-13 nmr Spectra of a 55 Shale Heated to the Indicated eratures for 24 Hours, Miknis Reprinted from Proceed ings of Symposium, by permission . gal/ton Colorado Retorting Tempand Maciel, 1981. the 14th Oil Shale 100 constant-temperature runs were carried out by the University of Utah Department of Chemistry on shale D. For t ,hese analyses, all samples were finely ground in a Spex shatterbox under a nitrogen atmosphere. Raw shale, cyclohexane extracted, and tetral1n extracted samples were ana lyzed. the spect ra of whi ch are shown in Fi gu re 4.17. The raw sha 1e was found to have an aromaticity of 0.19, a typical value for Green River sha 1es • Spent sha 1e samp 1es after therma 1 sol ut i on were found to have a slightly higher aromaticity: 0.26 after cyclohexane extraction and 0.25 after tetralin extraction. Although the tetra11n extraction was carried out at a higher temperature than the cyclohexane extraction (340°C vs. 305°C). i dent 1ca 1 • the aromaticities of the res idues are ne ar ly Compa red to F1 gu re 4.16, it is appa rent that s1 gn1 fi cant removal of aromatic carbon is taking place during thermal solution. It was expected, based on the results of Miknis and Maciel (19B1). that a higher extraction temperature would result in a more aromatic residue on the spent shale. This was not the case, however. Since both shale samples whose nmr spectra are shown in Figure 4.17 have nearly equal aromaticity. it was thought that tetralln might be slightly more effective at remov~ng aromatics A second set of than cyclohexane. spectra was obtained to test this hypothesis; this time spent shale samples were obtained by extraction of shale B with cyclohexane and tetralin resulting at nearly spent identical shale spectra temperatures. as well as Figu re that of 4.18 shows the raw the shale. Although the yields were the same (40 percent organic remova l) and the extraction temperatures differed by only 5°C, the aromaticity of the cyc 1ohexa ne res 1due 1s s i gn1fi cant ly hi gher than that of the tet ra 1 i n 101 A B C Figure 4.17 Carbon-13 nmr Spectra of 50 gal/ton Hell's Hole Canyon 011 Shale. A. Raw Shale: fa = 0.19 B. Cyclohexane Extracted Shale fa = 0.26, T = 305' C, 54% Yield C. Tetralin Extracted Shale fa = 0.25, T = 349' C, 70% Yield 102 A B C Figure 4.18 Carbon-13 nmr Spectra of 35 gal/ton Hell's Hole Canyon Oil Shale. A. Raw Shale, fa = 0.17 B. Tetra1in Extracted Shale fa = 0.20, T=321°C, 40% Yield C. Cyc10hexane Ext racted Shale fa = 0.28, T=326°C, 40% Yield 103 residue (0.28 vs 0.20). aromatics A somewhat greater selectivity for removal of tetralin is indi cated by this result. by 4. 2. 2.3 Analysis of spent shales from linear·heating runs. Carbon - 13 nmr spectra of spent sha 1es fro m ei ght 1i near - heat i n9 runs were obtained in order to f ollow changes in aromaticity (if any) as the maximum extraction temperature was varied . runs are illust rated in Figure 4.19. Spectra from several of the It is apparent from thi s figure that, as the maximum extract i on temperature i ncreases, both the aromatic and aliphatic peaks dimini sh in he ight, unlike the spectra of Figure 4.16, in wh i ch the aromati c peak rema ins rough 1y the same size regardl ess of r eto rting temperature . In the l owermos t s pectrum of Figure bot h aromatic are 4.19, the aliphatic and II pea ks" nearly ind ist in gu i s hable from the background noise, a dramatic contrast to the spectra of the spent shale from high-temperature pyro lys is retorti ng (uppermost spect rum in Figure 4 . 16) whi ch s hows no s ignal in the aliphati c regi on but a c learly defined peak in the aromati c region. As s ummarized in Table 4. 1 the aromati c ity of the spent shales from linear - heating run s varie s l itt l e with temperature, except for r un TI17 , The s pent s ha l e from this high - temperature (Tmax = 40S'Cj run had an est imated aromaticity of 0.40 ; however , due to the sm all signal (4.8 perce nt of original or ganic remaining on the spent shale) and the l imited pr ec i sion of the gr aphical integration tec hnique used to deter mine aromaticity, th is value is of questionable accuracy . A slight in crea s e in ar omat icity from the raw shale value of 0 . 27 t o the spent shale values is noted , which sugges t s that the small amount of eas ily extracted materia l (about 9 percent organic removed at 104 A B C --.~------..... ---------------------- D Figure 4.19 Ca rbon- 13 nmr Spectra of 43 gal/ton Hell's Hole Canyon Oil Shale used in linear-Heating Runs. A. B. C. D. Raw Shale , fa Tma x " 367"C, Tmax = 382"C, Tmax = 405"C, • 0. 27 fa " 0.29 fa " 0. 29 fa = 0.40 105 Table 4.1 Results of Carbon-13 nmr Analysis of Spent Shales from Linear-Heating Runs Fractional Run ID Tmax{ · C) Yield Raw sha l e fa Wa {g) a 0. 27 4.86 TT -7 287 0.095 0. 31 5. 05 TT -12 320 0.171 0.32 4.77 TT-9 338 0.241 0. 32 4.37 TT -14 353 0.320 0.31 3.79 TT-1 368 0.494 0.29 2.63 TT-15 374 0.602 0. 31 2.22 TT-8 382 0.682 0.29 1.66 TT-17 405 0.952 0.40 b 0. 35 a 8ased on 70 grams of raw shale , 25.7 weight percent organic. b Sma ll signa l -ta-noi se ratio makes thi s value unre l iable . 106 T<287-C) is more aliphatic temperatures . measurement s Si nee ;s ± 0.02 the than that material ac cepted (Pugmire, repeatabi 1ity 1983) , aromat i city of spent sha les after thermal constant at fa = 0. 305 ± 0. 015 . extracted at higher of aromat icity can be said that the it so lution in tetra',n is Thi s finding is notewort hy s ince the aromaticity of spent shales from pyro lytic processes appro aches 1. 0, and has important implications for reco very of kerogen from oil shales of higher aromaticity, su ch as those of the Antrim deposit in Mi chigan or any of the Kentucky 0; 1 shales. Also included in Table 4.1 are the calculated weights of aromatic carbon remaining in the spent sha le based on a raw shale wei ght of 70 grams. 25 . 7 percent of wh ic h 1S organlc carbon . At temper atur es above 320·C . the amount of aromati c carbon is observed to decrea se , wherea s no change in the amount of aromatic carbon in s pent shales fr om pyr o lyti c ret or ting has been observed . as is appar ent in Figure 4 . 15. 4.2.2 . 4 Th erm al so luti on of Antrim (Mic hi ga n ) oil shale. While the kerogen fr om Green River Formation oil shales is relatively low in aromat ic s and therefore exhibits relatively high conversion to oil in pyrolyt;c process ing. oil shales of higher aromaticity from different depo s it s yield considerably less of their organic carbon as oil upon pyrolysis . Such is the case with shales from the Antrim deposit in Mi chigan. whi ch typically yield only 45 perce nt of the organi c carbon as to volati l e produ cts, wh ereas a typical Colorado shale yields 75 percent of the organic carbon as volatiles (from data of Mik nis et a1., 1982) . As report ed by Mikni s and Ma c iel ( 1981) , aromaticities of about 0.50 are typical for Antrim oil shales as compared t o aromaticities of from 0.20 < 107 to 0. 25 for Green River shales . those from the Antrim For such highly aromatic shales as deposit or the Sudbury deposit in Kentucky (fa; 0.4 5), a recovery method which features effective remova l of aromatic carbons would subst an t iall y increase the attractiveness of the resource. Two runs were performed to asse ss the feas i bi 1ity of using the therma l solution process for recovery of organics from Antrim oil shale. In both cases, greater yield than that achieved in pyrolysis was observed; with tetralin as the solvent, the extraction yield was considerably higher than the pyrolysis yield. Using cyclohexa ne as the solvent, a yield of 50.5 percent organic removal was obs erved in a 24- hour extraction at 362'C . Tetralin extr action at 366·C re s ulted in 71.2 percent yield, also in 24 hour s . (With this shale. a temperature of 475"C rather than 450·C was f ound to give the most consistent results in the oxidat i on step of the procedure.) ability of tetralin or its greater Apparently the hydrogen-donor selectivity for extraction of aromatics makes it a superior solvent for the hi ghly aromatic kerogen of the Antrim shale . Although higher than the typical pyrolysis yield. the thermal so luti on yields for the Antrim shale were somewhat lower than those observed temperature: for He ll's Hole Canyon shale at a comparable interpolation of the data in Figures 4.2 and 4.3 to 365"C gives a yield of 85 to 90 percent for cyclohexane extraction and 80 to 85 percent for tetralin extraction. The rrore aromatic kerogen is thought to be the cause of the lower extraction yield observed from the Antrim shale alth ough other factors may also contribute . Further study of th ermal solution of highly aromatic oil shales is warranted based on these preliminary results, since a primary drawback to recovery of lOB organ; cs fr om sha 1es of the Eastern U. S. ; 5 the l ow convers i on to 0; 1 obtained in pyrolytic retorting . 4.3 Extract Analysis Two types of analyses were performed t o characterize the extracted mater; a 1: 5 imu 1ated di s t; 11 at; on by gas chromatography and e 1ementa 1 analysis f or carbon, hydr ogen , and nitrogen content. From the results of these analyses , several important characteristics of the extract were determined whi ch are indi cative of the dependence of the relative qua 1ity of the extracts upon the proces s ;og condit ions (temperature .. solvent used, and shale organic content) under whi ch the extracts were obtained . The characteri stics determined were boiling range, hydrogen- to-carbon (Hie) content . ratio, Inf ormation nitrogen-to-carbon regarding the (N/C) type ratio, and and nitrogen extent of further processing necessary to refine the crude extrads into fuels for a particular application may be determined from this information . 4.3.1 Simulated Distillation By following ASTM specification 0-2BB7 (1973), a rapid and reproducible determination of the boiling range of a hydrocarbon samp l e may be performed . Such a determination was carried out on samples of extracts after so lvent remova l . The presence of residual so lvent in the tetralin extracts was accounted for by subtracting the perc.entage of tetralin (as determined by CG analysis) in the sample. that -all of It was assumed the sample injected was eluted from the column, which corresponds to the assumption that no material of boiling point greater than about 530·C was contained in the samp le . No analysis wa s performed to determine the actual amount of residuum in the extracts. 109 In general, boiling information obtained by GC simulated distillat ion does not agree wi th that obtained by true dis t i llation (Aftens et a1., 1981), Simulated distillation tempe ratures are lower than tho se obtained by simple batch distillati on (by ASTM 0-86, 1972) in the lower boiling range, agree well at mi dpoi nt tempe ratures. and are somewh at hi gher at the upper range. The convenience of the simulated d1stillat ion rrethod in analyzing small samples and the relatively short anal ysiS ti me renders the techn i que invaluable as a means of comparing th e boi l i ng range of various samp le s and determi ni ng the effect .of Appendix E tonta; ns a process; n9 cond1t1 cns on the boil i 09 ran ge . tabula t ion of the simu lated 4.3.1.1 Cyclohexane extracts. cyclohe xane extract 4.20. d~stil1ation (sha le A. data. A typica l chromatogram of a 24 hours at 320°C) is shown i n Figure The low resolut ion of the simulated distillation technique is apparent i n the broad ri s e of the basel i ne fo l lowed by a gradua l decrease to the true base line at the end of the temperature program . The large peak at 0.69 minutes is the solvent pea k ( benzene). A fairly regular series of peaks is obser ve d between 12.70 and 22.20 minutes elut ion t ime ; th ese peaks are most likely due to the presence of a series of n-alkanes . pea ks are less re gu lar. At elution times of les s than 12 minutes . the The variation in the chromatograms of e xt racts of dHferent shale samples appeared primarl1y in the 7 to 12 minutes and greater than 22 minut es elut ion time ran ges. Between 12 and 22 minutes. most chromatograms were domi nated by the n-alkanes of 16 to 28 carbon atoms in len gt h . It is difficult to est ablish any furth e r struct ural features of the extract. and no analyses were perfo r med specifica lly for '" <D lSI J N f'- OJ M CO , f'- \j) -" .-I~" cr. (".J I.':J • ('I ",,(IJ~lDtr.oI'.,,:m'- • t'- M M f'J • .1'- .~'.":\JI~(\J • 'D I() • r.... (0 .,,, . ..:-.t. .J ,. _ .....S), _eJ.... cr'I\J , ,.lO ," "tir~~' '~":'f:~" II~~I~ ,f$/iO ;~~ ,- ~I • • 1..., (,' "" ~~w.:..w (T\ I').tI', .oor f'- " • r·. N"'" "'" a: lSI .'ro, '"• • Figure 4.20 Chromatogram of Typical Cyclohexa ne Extract -o JlI the purpose of structural elucidation. Figure 4.21 shows the plot of the boiling point distribution as boiling point versus the cumulative wei ght percent Appendix B) di st ill ed generated by th e program "SIMDlST" (see from the retention time and area perc ent data from the chromatogram in Figure 4.20. A noteworthy feature of the cyclohexane extract chromatograms t ypified by Figure 4.20 is the ab sence of any significant amount of material li ghter than a ClO par affin (elution time; 5.50 minutes) when compared to a typical Fi scher Assay shale oil (produced at SOO·C) , a chromatogram of which is s hown in Figure 4. 22 . The boiling point di stribution of the Fischer Assay shale oil i s shown in Figure 4.23 • • The occurre nce of extensive thermal cracking i s suggested by the pr esence of re 1at i ve ly 1ow-boi 11 ng spec i es ; n the Fi sher Ass ay oil, while little if any thermal cracking, thus few l ow boil ers, would be expe cted to be produced at extraction temperatures below about 350·C. limited thermal cracki ng, possibly aided by the presence of catalytically active miner al speci es in the inorganic portion of the shale, may occur in extractions carried out at temp erature s between 350· and 400·C. Thi s thermal cracking may be partially responsible for the general trend t oward a lower-boi 1; ng extract as extract ion temperature increases, as shown in Figures 4.24 and 4.25, and in Figure 4.26 below 350·C. was These figures illustrate the weight percent of the extract which found by GC simulated distillation to boil below the five arbitrarily selected temperatures: 200·, 275·, 375·,425·, and 470·C; for varying extraction temper ature s . The enhanced ability of the supercrit ica 1 so 1vent t o extract lower-mo lecul ar-wei ght materi al from 112 o o '" o o '" u 0 0 v I- Z 0 c... 0 0 n (!) --' Z 0 CD 0 0 N o o o o 20 40 60 80 100 CUMULATIVE WEIGHT PERCENT RUN NO. 8-C-l figure 4.21 Distillation Curve for Typical Cyclohexane Extract . 11 3 t:JeES!; .... ~ m u Co ...~ o E m 'o ...'" m f .c u ..... N N ~ .-'".." 11 4 o o '" o o on u 0 0 '" I- -Z 0 a... ~ 0 0 ,., z . ..J 0 CD 0 0 " o o o o 20 40 60 80 iOD CUMULATIVE WEIGHT PERCENT RUN NO. 12-FA-l Fi gure 4.23 Di stillati on Curve for Typ ical Fischer Assay Shale Oil Jl5 <200 275 300 325 350 375 <400 EXTRACTION TEMP ., DEG. C Figure 4.24 Variation of Boiling Po i nt Distribution fo r Cyclohexane Extracts of Sha le A (17 gal /ton) with Extraction Temperature 116 100r-------------------------~ >470 o <:> u o (!) w <470 o , I- 3 o ...J <425 W ID (!) z 50 H ...J H <375 o ID I- Z W U ~ W 0.. <275 <200 275 300 325 350 375 400 EXTRACTION TEMP., DEG. C Figure 4.25 Variation of Boiling Point Distribution for Cyclohexane Extracts of Shale B (35 gal/ton) with Extracti on Temperature 11 7 100r-------------~=0~--_, >470 u <470 (!) w 0 , I0 ...J W al (!) <425 0 :x 50 <375 z H ...J f-t 0 al IZ W U Q: W a.. <275 0 0 <200 275 300 325 350 375 ";00 EXTRACTION TEMP., DEG . C Figure 4. 26 Var i ati on of Boi1ing Point Distribution for Cyc l ohexane Ext r act s of Shale C (62 gal / ton) wi th Extrac ti on Temperature lIB the kerogen at increased temperatures may also contribute to the observed shift in boi l ing point distribution. An interesting difference between Figure 4. 26 for the cyc lohexane extract of rich shale and Figures 4.24 and 4.25 for lean and medium grade shales is the apparent maximum in production of low-molecularweight species which temperatures. an occurs at about 36S-C. At higher extraction increase in hi gher-boil; n9 compone nt s ;s seen. A possib l e explanation for the lower production of low-boiling species at hi gh extractio n temperatures is that any free radicals produced by thermal bond rupture are. in the absence of free hydrogen, combining with other radicals to produce a higher-molecular-weight species of higher boiling point than either of the combining radicals . The most dramatic los s of material occurred in the below 275-C fraction which decrea sed from 61 per cent of the extr act at 353·C extraction temperature to about 30 percent in the 380·C extraction. A corresponding decrease in the yield wa s also observed at extraction temperatures above 365·C with the rich sha l e (see Figure 4.2). from extracted species by the Production of insol uble material mec hanism mentioned previously. and subsequent depo s ition of this material on the sha le would r esu lt in a lower observed yield since the inso1ub1es would be burned off in the oxidation ste p of the experimental procedure (the weight loss from which is used to calcu l ate the yield). That no decrease in yield or loss of low-boiling material was observed with the lean or medium grade shales implies that any free radicals produced from ext racted species were sufficiently diluted in the extracting solvent so as to greatly reduce the probability of reaction of two free radicals to form a higher- I1g rno 1eeu 1ar-wei ght spec i es . Although the same amount of so 1vent wa s used in all runs , approximately two to three and one-half times the amou nt of organic mat er ial was placed in the autocl ave in runs with the 62 gal / ton shale as with the lean and medium gr ade samples, thereby increasing the concentrat ion of t he extracted materia l by a corres ponding amount. 4.3 .1. 2 Tetra' ; " extracts . A typical tetra';n ext ract chromato - gram i s illustrated in Figure 4. 27 (Shale O. 24 hour s at 320·C) . The l arge peak at 0.99 minutes is the solvent peak (benzene). Some residua l tetral;n remains in the extract after vacuum distillation, as evidenced by the peak at 11.02 minutes. material It is likely that some kerogen-derived wa s remove d during the distillation to remove the tetralin; however I on ly tetra 1in wa s detected by GC ana 1ys i s of the overhead. In comparing a tetralin extr act chromatogram before and af ter disti l lation , no significant changes were noted in peaks eluted later than 15 minutes after the start of the run . Any species that elute at nearl y the same time as tetralin would be ma sk ed by the large tetra l ;n peak in the raw extract 9 making difficu l t derived material the determination of the amount of kerogen- at that e l ution time . In ana l yzing the results of simulated di s til l atio n of tetra l i n extracts , it wa s ass umed that any kerogen - derived material lost with the so l vent in the di s t il l ation was insignificant compared to the tota l amount of extract . In Figure 4.28 9 the boiling point d is tribution corresponding to the extract chromatogram i n Figure 4 . 27 i s shown . The varia tion in the boi l ing point di s tribution of tetra l i n ext racts at var i ous tempe r atures i s shown in Figures 4 . 29, 4 . 30, and 4. 31 for s hale s A, B, and D, respectively. In gener al , tetra l i n 120 W81 .8' •• ~ ~ "- ~ ...o e ... ~ ...'"o ~ f ~ '-' Z 8 · 11 ~,.......,.. .... '" .. f' :0 .-'".. • • ·8 121 o o '" o o '" - u ~ 0 0 v I- z 0 "- 0 J. .., D '-' - ~/ ~~ Z ....J 0 (l) 0 0 N o C") o o 20 40 00 60 iOO WEIGHT PERCENT DISTILLED RUN NO. 25-T-1 Figure 4.28 Distillation Curve for Typical Tetralin Extract 122 <200 275 300 325 350 375 '100 EXTRACTION TEMP., DEG. C Figure 4.29 Variation of 80iling Point Distribution for Tetra1in Extracts of Shale A (17 gal/ton) with Extraction Temperature 123 100 >470 ~<470 U Cl <425 !oJ 0 , t- :z 0 ...J !oJ ED Cl 50 z H ...J H 0 ED <375 t- Z !oJ U a: !oJ ll. L <275 <200 0 2 75 300 325 350 375 '100 EXTRA CTION TEMP., DEG. C Fi gure 4.30 Variation of Boi l ing Point Distribution for Tetralin Extracts of Shale B (35 gal /ton ) with Extraction Temperature 124 100 >470 <> <> <> <> U <470 0 <425 (!) W Cl 0 , t3 0 ...J W III (!) 50 z H ...J H <375 0 III tZ W U a: w <275 0 Cl. 0 0 <200 0 275 300 325 350 375 EXTRACTION TEMP., DEG. 400 C Figure 4.31 Variation of Boiling Point Distribution for Tetralin Extracts of Shale 0 (50 gal/ton) with Extraction Tempera ture , 125 extracts were higher boiling and consisted of components having a narrower boiling range than the cyclohexane extracts . A sign ificant fraction of the compone nt s in the tetralin extracts wa s f ound to be in the boiling range 37S--42S·C . This variation in boiling range with solvent. together with the different temperature dependence of the yie ld observed for the two pure solvents, indicates that some aspect of the mechanism of extraction of organic matter is diffe re nt for the two solvents . As was observed for cyc l ohexane extracts, the boiling range of tetra',n extract s shifts toward lower temperatures as the extraction temperature increases, due in part to the occurrence of a limited amount of thermal cracking of the extracted material. illustrated in Figures 4.29, 4.30, and 4.31. This shift is For the rich and lean shales, the shift toward l ower -bOi li ng components illustrated in Figures 4.31 and 4.29 seems to be less pronounced than that observed for cyclohexane extracts of the same shales (Figures 4.26 and 4.24). the medium grade shale, it appears that the effect of For extraction temperature on the bOiling range of the extracts is similar for both tetralin and cylohexane extracts, although the tetra'in extracts are of higher boiling range. temperature, suc h as No decrease in boiling range with increasing was observed for the cyclohexane rich shale extract, was observed for tetralin extracts of any shal e, which is possibly indicative of the transfer of hydrogen from the so l vent to free radicals. If free radicals were to react with hydrogen atoms rather than other hydrocarbon radi cals , no polymerization of extracted speci es, thus no increase in boiling range, would be expected . 126 Compared to the cyclohexane extracts. the tetra';n extracts appear to consist of larger molecules in a form which is relatively una1tered from the parent kerogen. Qualitative observations of the solvent-free extracts uphold this assertion. Cyclohexane extracts were brownish- black in color and possessed an odor similar to that of a Fischer Assay oil. Cyclohexane extracts produced at higher temperatures seemed to be less viscous and would flow more readily than those extracts produced at lower temperatures. Tetralin extracts. on the other hand, emitted an odor reminiscent of that which one would perceive upon sniffing a block of rich oil shale at close range. These extracts were jet black in color, were somewhat shiny in appearance, and were semi-solid as opposed to a viscous liquid at ambient temperature. Therefore, liquid-phase (tetral;n) extraction seems to be a Ugentler" process in that fewer bonds are ruptured than in supercritical extraction, which is in turn gentler than pyrolysis. Tetralin extraction can be said to remove soluble pyrolytic bitumen from the shale, while cyclohexane extraction apparently removes kerogen from the smaller fragments shale, resulting of either pyrolytic bitumen or in a lower-boiling product than tetralin extraction. In both tetralin and cyclohexane extractions, the lowest boiling extract was produced from the rich shale. It is possible that richer shales contain more low-molecular-weight material than lean . shales or that the kerogen of rich shales is such that it is more easily degraded to smaller molecules. The medium grade shale yielded the highest- boiling-range extract of any shale sample and, as mentioned previously, the lowest yield at a given temperature. The diffusion limitation which 127 was postulated to cause the low yields may also be responsible for the higher boiling range of the extracts of this sha le. Haddadin (1982) proposed a mechanism for dissolution of Jordan oil shale in tetral;n which incorporated the diffusion li mitations within the shale . Conver- sion of bitumen to higher-molecular-weight asphaltenes was said to be a consequence of a diffusion restriction. Such a mechanism may be acting to a greater extent in the case of the medium grade sha le than in the other shale samples . The ability of lower-molecular-weight (Wi 11 i ams, 1981) . supercritical fluids components of coal to preferentially extract has been noted previously Although the structure of k.erogen is cons; derably different from that of coal, a similar effect has been observed in supercritical extraction of 011 shale kerogen in the present work. In comparing the boiling point distributions for tetralin and cyc l ohexane extracts. it is apparent that a broad spectrum of lower-molecular-weight species is present in the cyc l ohexane extracts which ;s not observed in tetra lin extracts. Kerogen is a comp lex multipolymer and would be expected to yield a wide variety of products under thermal cracking cond it ions; however, it is gener a lly agreed that 1itt 1e or no thermolysis accompanies supercritical gas extraction at temperatures of 350'C and l ower (8artle et a1.. 1982; Kershaw and Jezko, 1982) . Thermal cracking . therefore. can not be expected to be solely responsible for the product i on of the re 1at i ve ly sma 11 roo 1ecu lar speci es present ; n cyclohexane extracts. Rather, it is postulated that the supercritical state of the cyc l ohexane and its resulting capability to enhance the volatility of portions of kerogen that, together with limited 128 thermolysis, re su lts in an extract which ha s been con s iderably altered from the origina l kerogen and is of lower boiling range than the relatively unaltered tetra lin extract . 4. 3.2 Element al Analysis Extracts from constant -temperatu re runs in cyclohexane and tetralin and lin ear -heating runs in tetra',n were analyzed for carbon , hydrogen, and nit ragen. Appendix D. Camp 1ete resu 1t 5 of the se ana 1yses are presented in In this s ection, trends ;n Hie and N/C ratios and nitrogen content of the extracts are presented and discussed. 4.3. 2.1 the Cyclohexane extracts. cyclohexane extracts is only Generally. the HIe atomic ratio of slightly affected temperature, as illu strated in Figure 4. 32 . by extraction The values of the H/C ratios found for cyc lohexane extracts are similar to those of shale oils produced from Hell's Hole Canyon shale by the Union "8 11 and Paraho DH retortin9 processes which were reported by Lovell (1978) to be 1. 663 and 1.684, respectively . The H/C ratios for each of the re spective samples does not significantly differ from those of the original kerogen, which are represented by the solid symbols at the left of the figure . It can be asserted therefore, that changes in the structure of the organic matter which occur during supercrit;cal extraction result in a decrease in the size of kerogen fragments, as opposed to effecting significant changes in hydrocarbon type (which would alter the H/C ratio). The wide boiling range of components observed in the GC fingerpri nt of the typical cyclohexane extract (Figure 4. 20) supports the assertion that a decrease in mo lecu lar size to a variety of smal ler molecules has occurred during the extraction . 1.8 a H I- / I .7 lU 4: a:: l- x w c 0 I .6 ":c • I .5 0 0 I 4: a:: u KEROGEN 0 c V c V V V c V V V I- I .4f- 1.3t 275 I I I I 300 325 350 375 EXTRACTION TEMPERATURE, DEG. 400 C Figure 4.32 Hydrogen-to-Carbon Atomic Ratios of Cyclohexane Extracts QShaleA DShaleB 'VSha1eC ~ '" '" 130 An observed decrease in residue Hie ratio with increasing extraction temperature (Figure 4.8) viewed together with the constant extract Hie ratio implies either that some hydrogen·rich fragments (H/C>2) are converted to gases or that significant amounts of material of low Hi e ratio (aromatics) are not extracted. It is felt that it ;s a combination of these two factors that explains the observed data. The high conversions of organic matter observed (>90 percent) indicate that some aromatics are being extracted, since Green River kerogen typically contains from 20 to 25 percent aromatic carbon (Res;g et al. t 1978 ; Miknis et al ., 1982). while observations of residual gas pressure indicate that gas production increases at extraction temperatures above 350·C . loss of hydrogen or hydrogen - rich fragments of kerogen to gas at higher temperatures would result in a lower H/C ratio of the residue without altering the extract H/C ratio, assuming that the gases were produced from the kerogen~ rather than the extracted materi al e Figure 4 . 33 shows that extract N/C ratios clearly increase with increasing extraction temperature for cyclohexane extracts of each shale samples which is as expected since heterocycli c nitrogen structures are more re sistant to degradation extraction temperatures. and become soluble only at higher Compared to the N/C ratios of the original kerogen, the extract N/C ratios of the rich grade sha le (shale C) are lower than the kerogen N/C below 350·C extraction temperature, greater than the kerogen N/C at temperatures above 350·C . but That bot h re sidue and extract N/C ratios are higher than those of the kerogen of each sample indicates that very little nitrogen is converted to gases . The data of Fischer (1982) for retorting of oil shale cubes in an inert 2.6 A 0 0 - * v u "Z t- u < a::: t- 2.4 o 2.2 oj, 2.0 KEROGEN ~ X I .6 V V •e .. 275 o V V Vv I .8 W o o o 0 V o o I 300 325 350 375 400 EXTRACTION TEMPERATURE, DEG. C Figure 4.33 Nl trogen-to-Carbon Atomic Ratios of Cyclohexan. Extracts OShal. A OShal. B 'i7Shale C -w 132 at mosphere indicate that all kerogen nitrogen was accounted for in the organic residue or in the shale oil. The nitrogen content of the cyclohexane extracts was high compared to that of most crude oils and increased with increasing extraction temperature as shown in Figure 4.34. Varying the extraction temperature affected the nitrogen content of the medium grade sha le extracts the most; nitrogen increased from 1. 58 percent at 325 -C to 2.24 percen t at 375·C. In comparison, Lovell (1978) reported nitrogen contents of 1.93 percent and 2. 09 per cent in shale 011s produced from Hell's Hole Canyon shale by the respectively. Union "SOl and Paraho OH ret orting processes, The nitrogen contents of cyclohexane extracts are simi lar to those of pyrolytically·produced shale oils. 4.3.2.2 Tetra1in extracts. Figure 4.35 shows the HIe ratios determined on a so lvent-free basis of extracts fr om constant-temperature tetralin runs. As with cyclohexane extracts. extraction temperature did not Significantly alter the extract HIe ratio. In all cases, the extract HIe rat ios were lower than those of the original kerogens, in contrast to the cyclohexane extracts, which had HIe ratios simi lar to those of the original kerogens. This result, taken with the observation that the extract HI e ratios were lower than the kerogen HIe ratio, indi cates that tetralin preferentially extracts lower Hie (more aromatic) portions of kerogen in constant-temperature extractions. As seen in Figure 4.36. Hie ratios of linear-heating tetralln extracts varied considerably, but no dis cernable trend is evident due to the scatter in the data. ratios Except for two data points, the extract HIe are within to.l of the value of 1.556 determined for the 2.5 ~ , 2.3tz w o (!) ~ IH z I- u « ~ l- x w o t- 2. It- o o t- 1. 9 t- "IV V 1. 7 t- 275 0 o V t- r 1.5 V V o V o o I I 300 325 350 I 375 400 EXTRACTION TEMPERATURE, DEG. C Figure 4.34 Nitrogen Content of Cyclohexane Extracts OShaTe A OShaT. B V'ShaT. C w w 1.8 0 H I- 1.7 0:{ ~ u ":r: l- u , 1. 6 t0 I .5 0:{ ~ lX w vi KEROGEN V V Vv 0 I .4 1.3t 275 0 0 ~ V OVO I I I I 300 325 350 375 EXTRACTION TEMPERATURE, DEG. 400 C Figure 4.35 Hydrogen-to-Carbon Atomic Ratios of T.tralin Extracts , Constant-Temperature Runs OShal. A OShal. B 17Shal.O .,.w ~ 1.8 l 0 H I- IJ 1 .71- IJ « ~ u "I 1 .6 I- 1.5 U IJ w IJ KEROGEN IJ ~ IJIJ IJ • « IX IJ IJ IJ IJ IJ IJ 1 .4f- 1 • 31 275 1 1 1 300 325 350 1 375 400 MAX. TEMPERATURE OF RUN, DEG. C Figure 4.36 Hydrogen-to-Carbon Atomic Ratios of Tetralln Extracts, linear-Heating Runs ~ w ~ 136 kerogen. It is not known why the constant-temperature tetralin extracts have Hie ratios lower than th ose of the original kerogens but linear heating extracts have HIe ratios similar to that of the kerogen of that shale sample . suspected~ It i s however, that the difference in the amount of time that the sample was exposed to high temperature in the two types of runs may be a factor . Figures 4.37 and 4. 38 show the N/C ratio s of constant -temperature and linea r-heating tetra' in extracts, re spective ly. With the exception of the constant - temperature extracts of sha le B. a distinct increase in N/C ratios with increasing temperature is seen, as was observed with cyclohexane extracts . As expected, extract nitrogen content increased with temperature for all samples except shale 8. as seen in Figures 4 . 39 and 4.40 . Nitrogen content also increased wi th i ncreas i n9 organi c content in the constant - temperature runs . constant-temperature The relatively l ow nitrogen content of the extracts (Figure 4. 39) was unexpected. The nitrogen content of the lean shale extracts ranged from 0. 58 percent to 1.04 percent. which is from one-third to one-half of that observed i n cyclohexane extracts of the same shale . Only two co nsta nt- temperat ure extracts had a nitrogen co ntent greater than 1.7 percent . ratio of the insoluble residues of Since the N/C constant -temperature tetralin extractions did not significant ly increase (with the exception of two samples for which the suspect, as noted previously), upgrading of accuracy of it the extracts occurs, transfer abilities of tetral;n the is nitrogen suspected possibly aided and the determination was that some in-situ by the hydrogen - l ong residence time of the , " 2.4 "00 -v 2.0 * 1 .8 u 1.6 z 1 .4 ....... l- u 1 .2 ~ 1.0 « l- X W V 2.2 lEROGEN ... V • • o V V V 0 V 0 0 0.8 0.6 275 0 0 V 300 325 350 375 400 EXTRACTION TEMPERATURE, DEG. C Figure 4.37 Nitrogen-to-Carbon Atomic Ratios of retralin Extracts. Constant-Temperature Runs o Shale A 0 Shale B 'i7Shal. 0 ~ w " ,. 3.0 0 1"\ 0 0 - 0 2.5 * • V u "z r 0 KEROGEN 0 0 OJ 0 2.0 tU 0 0 « 1.5 ~ tX 0 lIP O w 1.0 275 300 325 350 375 MAX. TEMPERATURE OF RUN, DEG. 400 C F1gure 4.38 N1trogen-to-Carbon Atom1c Rat10s of Tetral1n Extracts, l1near-Heat1ng Runs w CD 2.5 ~ V , z w 2 "V C!> 0 ~ tH z 1.5 l- t) <t ~ V r "V o "V "V 0 0 I tX 0 O W 0 V 0.5 275 300 325 350 400 375 EXTRACTION TEMPERATURE, DEG. C Figur. 4.39 Nitrog.n Cont.nt of Tetralin Extracts. Constant-Temperature Runs OShal. A OShal. B '\7Shal.D ~ w '" 3 0 ~ z , w 0 2.5 0 ~ H z o 2 I- <t 0 QJ 0 0 0 IDI U ~ 0 0 (!) I- 0 1 .5 l- X w 0 t 1 275 I I I I I 300 325 350 375 400 MAX. TEMPERATURE OF RUN, DEG. C Figure 4. 40 Nitrogen Content of Tetralln Extracts, linear-Heating Runs OShale A OShale B 'VShale 0 -... C> 141 extract ion (24 hours) . Extracts of the shorter-res idence-t ime 1inear- heating runs (Figure 4. 40) had higher nitrogen contents~ ranging from a l ow value of 1.30 percent to a maximum of 2. 86 percent. Only one . linea r - heating extract had less than 1.7 percent nitrogen, the highest nitrogen content of any constant-temperature extract. Above about 360·C . the nitrogen content of linear':"heating extracts was higher than that of cyclohexane extracts . 4. 4 Kinetic Study Since the early work of Maier and Zimmerly (1924 ), researchers have used a variety of experimenta l approaches to the problem of elucidating the mechanism of conversion of kerogen to oi l and determining values of kinetic parameters to mathematically describe the decomposition . Most studi es agree th at the decompos it i on mechani sm is comp 1ex and proceeds via one or ;nore intermediates, the identity of which is often rather nebulou s. However, the existence of an intermediate ca lled bitumen, defined as that material which is soluble in common organic solvents, is fairly well agreed upon. Further, it is agreed that bitumen formation from kerogen takes place at temperatures well below those necessary for oil production. I n order to more fu 11 y character; ze the therma 1 so 1ut i on of oil shale kerogen, a kinetic study of the rate of conversion of kerogen to solub le bitumen was carried out. At the time the study wa s i niti ated, no published data on thermal solution kinetics for Green River oil sh a le kerogen were available, although considerable l iterature on coa l dissolution in various solvents was reviewed (for example, Wiser et al . , 1971; Lytle et a1., 1980; and Traeger, 1980). In mid-1980, the work of 142 Haddadin dea ling with the kinetics of tetralin extraction of Jordan oil shale wa s published. Tha t work was limited to a temperature range of 229--315·C for untreated shale (study of the extraction of decarbonated shale was extended to 360·C) . A mechanism which accounted for diffus ion limitations at low temperatures (T<260·C) was proposed and activation energies were determined for the two dissolution pathways . studied the pyrolysis intermediate. of torbanite kerogen to Cane (1951) a benzene-soluble His kinetic analysis showed that the pyrolysis fol l owed a first-order rate law with an activation energy of 48 . 5 kcal/mole in the temperature range 350'-400'C. The present kinetic study covers a higher temperature range (2Br- 410·C) than that of Haddadin1s study, and is co ncerned with the di sso 1uti on of Green Ri ver 011 sha 1e kerogen, wh i ch mi ght be expected because of its different origin and geological his tory to behave differently than either the Jordan shale st udied by Haddadin or the Australian torbanite s tudied by Cane. Insight into the mechanism of kerogen decomposition to bitumen might be gained by the kinetic study, as well as the elucidation of the kinetics of bitumen formation, rather than oil kinetic formation, study, in as is addition usually studied . to obtaining The objectives of the information pertaining to kerogen decomposition at moderate temperatures, were to determine the intrins i c rate of production of soluble material insoluble kerogen, to determine the numeri c al (bitumen) from the values of the kinetic parameters necessary to mathematically describe the conversion, and to propose , ba sed on the data, a plausible mechanism for the initial stages of kerogen decomposition whereby a soluble intermediate i s formed . 143 Tetra11n was used as the solvent in linear-heating runs for several reasons. First, it was desired to use a , pure solvent in order to facilitate analysis of extracts and residues from these runs. Second. cyclohexane was judged to be unsuitable s i nce the strip-chart record of the interior temperature from preliminary runs with this solvent showed a nonlinearity in the heating ramp at about 2aOoe , perhaps due to a phase-change phenomenon at the eriti ca 1 temperature. Thi rd, as discussed in Section 4.3.1, analysis of the extracts from constanttempe rature runs showed that tetral;n extracted a material that could be considered as bitumen due to its high and narrow boiling range characteristics. whereas the cyclohexane extracts were found to be ITJ')re similar to a Fischer Assay oil than bitumen. All re ported linear-heating runs were made using 70 grams of shale E (43 gal/ton) and 500 milliters of tetralin . the heating ramp was .., calculated from O.197°C /mi n. reasonably good -- actual recorded Thus, The reproducibility of all temperature traces runs were i dentical extraction temperature rea ched. sample heating rates varied from sigmOidal t to except for the maximum Figure 4.41 shows the yields determined for various maximum tempe ratures in linear-heating runs. the curve is 0.190 as expected, The shape of just as would be observed in plotting the quantity lIone minus the fractional weight loss" as recorded in a TGA experiment. From these data, kinetic parameters may be calculated. 4.4.1 Theoretical Development of Kinetic Analyses The derivation of the basic equation from which mathematical analyses have been developed to determine kinetic parameters, as well as c w > 0 L: W ~ u H z « (!) ~ 0 ~ , C -I W H ~ 100 DO t 0 t- 0 0 50~ 0 0 0 ~ 0 [IJ o 0 DO 0 275 I2J 0 300 325 350 375 400 425 MAXIMUM TEMPERATURE OF RUN, DEG. C Figure 4.41 Yield vs . Maximum Temperature in Linear-Heating Runs. 43 gal/ton (Shale E) Hell '5 Hole Canyon Oil Shale. Heating Rate = 0.2°C/mln Solvent: Tetra1in -...... 145 the equations that the analyses are based on , will be prese nted in this section. It is assumed that the isothermal rate of conversion of a substance to decomposition product s may be expressed as a function of a rate constant, k, dependent dependent only on so lely on temperature, the fra ct ion of and some function f, original reactant which * decomposed: (4.1 ) = k(T}f(x}. Changing the independent variable to has temperature by making the substitution, B = *" (4.2) and writ i n9 the Arrheni us form for the temperature dependence of the rate constant gives; The form of f(x) dx or = iA exp (-E/RT}f(x) . (4.3) is either chosen ba s ed on prior knowledge of the decompos ition mechanism of the reacting material or it may be determined by trial-and-error to best fit the experimental data. Equation 4.3 expresses the rate of conversion with respect to temperature in terms of the activation energy (E)9 the pre-exponential factor (A), and the heating rate (6), in addition to the absolute temperature and the conversion . It is the basic equation from which the various mathematical analyses for determination of kinetic parameters begin. Since the first serious theoretical treatment of thermo- 146 gravimet ri c data by van Krevelen et a1. (1 95 1), numerous analyses based on different mathematl c a 1 man i pu 1aU cns of equat i on 3 have appeared in the l iterature . integral Three gener al types of analyses have been deve loped: methods, which utilize conversion ver sus temperature data directly; differen tial methods, which utilize rate of conversion data; and difference-differentia l rates . methods, which involve differences in One of the roore commonly applied methods of analysis of each genera 1 type wa s se 1eeted; the; r deve 1opment and app 1; cat i on to the present data is presented next. 4.4.1.1 Integral method . The integ r al method chosen to apply to kerogen decompositio n wa s that developed by Coats and Redfern (1964). It ha s been previous ly applied to oi l (Rajeshwar, 1981). shale decomposition kinetics The mathematical development begins with Equation 4.3. dx or = ~A exp (4.3) (-E /R T)f(x) . Application of thi s method to thermal decompo s ition data requires either a priori ass umption of the f orm of f(x) or a fonn of f(x) as determi ned by previous experiment. Since the majority of researchers in oil shale de compos ition have found satisfactory resu l ts using a first - order form of the reaction rate (for example: Hubbard and Robinson, 1950; Campbell et al, 1978 ; and Haddadin, 1980) , f( x) was chosen as : (4 . 4) fIx) = I-x , which describes first-order dependence of fraction of un converted or9anic material. the reaction rate on t he 147 Substitution of equation 4.4 into the basic equation f ollowed by rearrangement and integration gives x dx I o r-x = !" IT exp(-E/RT)dT. (4.5) To Assuming that the lower limit of the temperature integral on the righthand side of equation 4.5, To. i s the l owest temperature at which the linear heat ing rate holds real meaning with regard to the process under investigation and that conversion is unmeasurable at lower temperatures, equation 4. 5 may be rewritten as dx A T 10x r-x = i 10exp( -E/RT)dT . (4.6) Integration of the right -hand side of equation 4.6 can not be performed analytically; however, a number of different approximations to the integral have been derived, usually incorporating the substitution: (4 . 7) u = E/RT. Making this substitution in equation 4.6 gives x dx AE I o r-xx = BId a GO e- U - u u2 duo (4.8) Coats and Redfern (1964) inte9rated equation 4.8 by making use of the following approximation: -= U I-be -u '""' ~ m=O (4.9) 148 with b = 2. When b=2, there are three terms in the surrmation; if the third term is small, equation 4.10 results: ARTz [I - In(1 -x ) -- sr- - t2RT] e -E/RT • (4 .10) Rearranging and taking natural logs gives E -lIT ln [-I n(I-X) ] = F (4 .11 ) In equation 4.11, the first term on the right-hand side is essentially constant for typical values of E and A over the range of temperatures in which most rea ctions occur; therefore, a plot of the left-hand side versus reciprocal temperature should give a straight assumed form of f(x) is correct) with a slope of -E /R. l ine (if the Such a plot of the data for conversion of kerogen to bitumen in llnear-heating runs (Figure 4.41) is shown in Figure 4.42. Immediately noticeab le in Figure 4.42 are the two distinct straight lines of different approximately 350·C. 0.30. slope , The the inflection conversion at between this which temperature occurs is at about Linear regression analysis of the two line ar regions resulted in the ca lcu lation of values of 14.5 kcal/mole and 28 .4 kcal/mole for the activation energy in the l ow - temperature (T<350·C) and high-temperature (T>350·C) regions~ respectively. The Coats and Redfern method does not provide f or ca l culation of the pre-exponential factor. D D L5J D FIgure 4.42 Integral AnalysIs (Coats and Redfern) of lInear-HeatIng YIeld Data -... '" 150 While the numerical values of activation energies do not necessarily have mechanistic significance (they mayor may not be indicative of actual reactions that are occurring), it is significant that two straight lines of different slope are observed . The fact that the data points fall in straight lines validates the assumption of a first-order decomposition, while a competitive decomposition mechanism is suggested by the determination of a high activation energy at high temperatures and a low aet;viatian energy at l ow temperatures. result This implies that kerogen conversion to bitumen can occur by two different pathways, one of which is followed at low temperatures, the While the integral method of Coats and other at high temperatures. Redfern has been successfully applied to systems which decompose by a simple mechanism, the accuracy of the kinetic parameters determined for cases involving multiple reactions, such as may be the case for kerogen , is suspect (Flynn and Wall, 1966). 4.4.1.2 Differential method. Mathematically, the differential method used -- the customary Arrhenius plot -- is the simplest. In some cases, differential methods are able to circumvent difficulties inherent to many integral methods (F l ynn and Wall, reliable parameter estimation. 1966), allowing a more A rearran9ment of equation 4.3 gives In[dX/dT] I-x A E = ln i-lIT (4.12) As with the i ntegral method, successfu l determination of A and E rests on choice of the correct form of f(x), which was again chosen to reflect first-order dependence of the decomposition rate on the fraction of 151 The Arrhenius unconverted kerogen . plot method is inferior to the differential method of Friedman (1965) in that it does not r i90rously check for the constancy of rates. kinetic parameters at several heating It should give a reasonably accurate estimate of the parameters, however. Fi gure 4.43 shows the Arrhenius plot, the left-hand side of equation 4.12 plotted versus reciprocal temperature. To construct this plot, as is necessary in applying any differential ITEthod. values of the rate of conversion Considerable with scatter respect resulted derivative. AX / AT. was to when calculated; temperature the were di fference consequently. a required. form nu mer i cal of the formula given by Sestak et al. (1973) was used to calculate these values: (4.13) In applying this formula, values of conversion at regular temperature intervals were required. regular interva ls, experimental a conversion Since the experimental data was not taken at smooth curve was versus temperature han d-d rawn data points. through the from which values of conve rs ion were "picked-off" at four degree intervals . By hand-drawi ng the curve, mathematically ford ng the data to fit some function was avoi ded. As was apparent in the Coats and Redfern plot, Figure 4.42, two straight l ines of differing slopes are observed in the Arrhenius plot; the inflection occurs at about 350°C. 51 opes and intercepts were determined by linear regression, and the calculated kinet i c parameters are: 7 o 6 5 ~ -0 X - D D 4 ...... 1 X ~ 3~ E=44.8 keol/mole 13 C A=I . I*10 /mln D - E=19 . 9 keol/mole 4 A=2 . 2*10 /mln D D D 2 D D I 01 I 1.4 1.5 I 1.6 1.7 I I 1.8 liT, K -I *10 " Figure 4.43 Differential Analysis (Arrhenius Plot) of linear-Heating Yield Data -'" N 153 T<350 0C: E1 Al T>350 oC: E2 A2 = 19 . 9 kcal/mo l e = 2.2 x lOIt./min, = 44.8 kcal/mole = 1.1 x 10 13 /min . Results of the differential analysis of the experimental data are a gai n i ndi cat i ve of a campet it i ve decamp as 1t i on mechani sm, a lthou gh the activation energies are significantly higher than those found from the integral analysis. Similarly, Rajeshwar (1981) found that activation energies calculated by the Coats and Redfern rrethod were somewhat l ower than those found from the Arrhenius method for decomposition of kerogen 1n a nitrogen atmosphere. 4.4.1.3. to ~nalyze Difference-d~fferential method . The third method chosen the experimental data is the difference - differential method developed by Freeman and Carroll (1958) . Freeman and Carroll derived equations for 1 rreversible reactions from which the activation energy and react i on order may be determined graphica ll y . Although the rrethod has received crHicism due to its inevitable magnificat i on of experimental scatter, especially at Rajeshwar, l ow conversions (Sestak et al., 1973; 1981), it seems to be the most widely applied method of analysiS of thermogravimet r ic data (F lynn and Wall, 1966) , possibly because on ly one experimenta l trace is requi red to dete rmi ne a value of the reaction orde r , an assumed parameter in other rrethods. The development of the Freeman-Carroll equations begi ns, as with the previous rrethods , with equation 4.3 ; however, the reaction order, ", is to be determ1ned: 154 ~ = After taking the natural (4 .14) A exp ( _E /RT) ( I_x)n. logarithm of each term in equation 4 .1 4, the following expression i s obtained: dx E (4.15) lnsa;' = ln A - lIT + n In(1-x). Equation 4. 15 can then be written in difference form, 01n~ = -=} (+) ( 4 .16) + n .1n(l-x), where the term lnA has vanished Slnce A i s assumed constant. Equation 4.16 can be rearranged two ways, by dividing the entire expression equation, by either o(IIT) or oln(l- x) . simi lar graphically . values of kinetic I n the present study, From parameters either may be resulting determined the equat i on used to determi ne kinetic parameters is oln~ .1n(l-x) E =-1f+n o1 T • 1 T (4.17) Values of the rate of conversion were required in applying this method; they are th e same values as those calculated for the Ar rhenius method . A plot of oln~ • 1 T .1n(1-x) versus o1 T 155 should result in a straight line of slope n and intercept -E /R . Figure 4.44 shows such a plot for the high conversion " range of the experimental data (0.41 < x < 0.99). At these hi gh convers i cns, the react; on order was f ou nd to be 0.95 (a very good approximation to 1.0), which further verifies the first-order assumption which was made in applying the previous The calculated two methods. activation energy is 41.3 kcal /mo le, which is reasonably close to the value of 44.8 Kcal / mole determined from the Arrhen ius plot at high temperatures. Notably, a conversion of 0. 41 corresponds to roughly 360·C" which ;s close to the inflection point of about 350·C observed in Figures 4.42 and 4.43. At conversi ons lower than 0.41, interpretation of the data was di fficult due to cons iderable scatter, alth ough two other linear regions could be discerned: one in the conversion range 0 to 0 . 17 with an activation energy of 30.3 kcal/mole and a reaction order of 2.8; the other at conversions of from 0.17 to 0.41 with an activation energy of 15.3 kcal/mole and a negative reaction order of -0 . 60. The numerical values of E and n calculated at low conversions are judged unreliable due to the inherent difficulties in applying this method. Although the accuracy of the values of E at low conversions is questionable, an additional regime or regimes of lower activation energy than that observed at high conversions is suggested, which again hints at the ex istence of a competitive decomposition mechanism. More so than with the Coats the kinetic and Redfern and Arrhenius plot methods, parameters ca 1cu lated for compet it i ve react; ons by the Freeman-Carro 11 meth od must be regarded wi th skepticism (Flynn and Wall, 1966). The values of nand E calculated at high conversions by the Freeman-Caro11 method are "reasonable," however, and may be considered as leg i timate. 100r,____________________________________- , 80 1'1 (S) - 60 * ,~I 40 xII-U, - -<lc <l E=41 .5 n=0 . 95 r ./ [] 20 0 -20, ' o , 20 40 60 80 100 120 l:.In<t-X) .. 10 3 61fT Figure 4.44 Difference-Differential Analysis (Freeman-Carroll Method) of Li near-Heating Yield Data ''"" 157 4.4.2 Kinetic Model Three analyses have been applied to the experimental conversion versus temperature data, two of which strongly suggest the existence of a compet i tive decomposi tion mech anism for conversion of kerogen to bitumen, while the other indicates the occurrence of a high-energy rea ction at high conversions and the possibility of a lower-energy reaction at lower conversions. macroscop~c It was therefore decided to propose a decomposition scheme consisting of a parallel or competitive mechanism which had the additional feature of accounting for gas formation. which was found to increase markedly above 350°C: Kerogen I - -- -» Bitumen T<350 0C Bi tumen + Gas T>350 0C. 2 It is not inferred by this mechanism that the characteristics of the bitumen re covered at high temperatures are significantly different from those of the low-temperature product observed in the extract analysis. no evidence to this end was The competitive rrechanism rrerely reflects the evidence obtained in applying mathematical analyses to the experimental data -- that two possible pathways exist for bitumen formation. In order to rrore accurately ascertain the values of the kinetic parameters (activation energy and pre-exponentia l factor) for each of the pathways, the experimental data was fit to an analytical expression for conversion as a function of temperature. Four parameters were 158 adjustible in this expression: E1 • AI. E2 • and AZ. rate of k.erogen decomposition with respect An equation for the to time, .dx/dt, can be written in terms of absolute temperature and the amount of kerogen present as follows: dx : k(T)f(x). (4.18) dt Assuming competitive first-order reactions, equation 4.18 becomes (4.19) where kl and K2 are the temperature-dependent rate constants for the two reactions. By substituting the Arrhenius fann of the rate constant and changi n9 the independent va r i ab 1e to temperatu re by 1ncorporat i n9 the ~heating rate. a, equation 4.19 may be written (4.20) This equation is then integrated by separating variables, (4.21) then carrying out the integration from zero conversion at some temperature, To. to some conversion x at T; (4.22) The r ight-hand side of equation 4.22 may be integrated by parts after maklng the substltutlon zl • E1 /RT. 159 [ .=C z, -In ( l- x) _ez , + [ ~z, where the lowe r limit of f . ez , ·1 ' , z, -d the integration in equation 4.22 has been changed t o zero before carrying out the integration. tion by parts of t he (4.23) Z Z remaining integ rals justified since the same expression re curs. Further i ntegra- in equation 4.23 1s not By calling the terms 1n brackets P(z l ) ' and P(z2)' an expression f or the fra ctiona l conversion may be written: x = I-exp [ - A, E, BR p (z,) - A,E, BR p(z,) 1• (4.24 ) An expression for P(zi) exists 1n terms of an expansion in a series of Bernoulli nu mbe rs (J ahnk.e et a1.. 1960): Zi = _e~ zi [ -0 • 0000035 + 0.998710 + 1. 98487646 Z z2 i i + 11. 7850792 + 20 . 452340 + 21. 14 914 69 + 9.5240411 z 3 Z4 z·i zS i i i ± 0. 0000035 J. zi Us i ng equations 4.24 and 4.25, = -Ei/RT (4. 25) ( 2. the conversion can be calculated explicitly at a given tempera ture. Experime ntal data were fit to equat io n 4.24 by minimizing the least squa re s residua l. denoted S. of the difference between the experimental 160 yield, Yj. 1 •• •• • 18. and the calculated conversion, Xj. at the same Tj , j = Mathematically. To minimize thi s function, which has the form (4 . 27) the simp lex function minimization method of Nelder and Mead (1965) was utilized. A FORTRAN computer code originally written by P. E. Fischer and R. J . Bezama was adapted to the problem at hand (see Appendix Fl . A guess of the four parameters AI' A2 • El _ and E2 was required to initialize the routine . For this purp ose, values of E1 and E2 obtained from each of the graphical methods were used . Values of Al = I x l OS/mi n and A2 = 1 x lOll/min were used in conjunction with the values of E1 and E2 found fr om the integral method; however, in this case the routine did not satisfactory converge. implying that the starti ng guesses were not sufficiently close to the function minimum. When the kinetic parameters found by the Arrhenius plot method were used as initial guesses, convergence to reasonable values of the four parameters occurred . Convergence to simi 1ar va 1ues was observed usi ng the hi gh - temperature act i vat ion energy found from the Freeman-Carroll method used in conjunction with the values of Al' E1, and A2• Converged values of the kinetic parameters were found t o be: 161 A, • 2.2 x lO'+ / mi n, A, = 1.7 x 1013/min, E, = 20.8 kcal /mo 1e. and E2 = 45.7 kcal/mole. A least squares residual of S = 0 . 015 resulted from the min'i mization routine. From the magnitude of the "apparent" activation energies, it can be said that, on the average, weaker bonds are bei ng broken at lower temperatures temperatures . (T <350°C) and strong bonds are be; n9 broken at hi gher Also apparent is that diffusion limitations did not affect the observed yield to any significant degree . These are average values of the kinetic parameters. representat i ve of the broad spectrum of react ions actually occurring in the breakdown of kerogen. These kinetic parameters, together with the ki netic model proposed, might be used in pred~cting kerogen decomposition to bitumen at low to rroderate temperatures or under such conditions that diffusion restrictions within the shale particles is not rate limiting. Reasonable agreement with the limited amount of published data regarding conversion of kerogen to a solvent-sus ceptib le intermediate is noted . As mentioned previously, Cane (1951) rep orted an activation energy of 48 . 5 kcal/mole for conversion of torbanite kerogen to benzeneso l uble bitumen in the tempe rature range 350°-400°C, wh i ch corresponds well to the value of 45.7 kcal/mole found in the present work for 162 temperatures in the range 350°-410°C. Haddadin (1980) found a value of 20.8 kcal/mole in low-temperature (260'-315'C) thermal dissolution of Jordan oil shale, which is very close to the value of 20.5 kcal/mole reported herein for the 287°-350°C temperature range. That such close agreement with literature values of kinetic parameters was found for sha 1es of va ryi n9 gee 1091 c hi story ; s unexpected and may i ndi cate that different types of kerogen undergo decomposition through similar mechani sms. In Figure 4.45 is shown the conversion as calculated using the kinetic parameters found from the least squares fit to the data in equation 4.24 and 4.25. The closeness of fit indicates that the competitive react ion model, consisting of two alternate decompos1t1on pathways, is decomposition adequate to in soluble macroscopi cally bitumen. The model describing does not kerogen 1ncorporate diffu sion resistances which would presumably occur at higher heating rates and higher kerogen conversion rates. would manifest itself in the Such a diffusion restrict10n broadening of the conversion versus temperature trace. so that removal of s olub le material from the shale would take place over a wide r temperature range. It was found that the amount of natural bitumen, determined by exhaustive extraction of the raw shale with cyclohexane to be 8.91 percent of tota l organic. agreed well with the minimum yield .in linear heating runs (8.7 percent of total organic). Therefore, in fitting the data to the analytical expression for conversion, the data was adjusted to account for the presence of natural bitumen 1n the shale, removal of which was not r egarded ~s kerogen decomposition. A correction to adjust , .0 0 UJ > >: 0 UJ a: 0 z -< C) a: 0 ....z 0.5 UJ 0 a: UJ D0 ~ • --' UJ >- I 0.0 250 S~ 300 350 400 450 TEMPERATURE !DEC C) Figure 4. 45 Conversion Calculated from Kinetic Model (Equation 4.24) Compared with Experimental Data from Linear-Heating Runs 'w" 164 the data so that the maximum observed yield wa s 100 perce nt was als o app 11 ed . By app 1y; n9 the se adj ustment 5 , the experi menta 1 yi e 1d ranged from zero to 100 percent of total organic. corrected yield (%) The correction applied was: = ~~O~b~S~,~,~·e~l~d.+%~)~-~na~t~u~r~a~l~b~i~t~u~m~en~~~x 100 max . obs . yie d - natura bitumen (4.28) The curve in Figure 4.45 represents the least -squares fit of the corrected yield to equation 4. 24 . adjacent to the experimental To plot the least - sq uares fit data, the calculated conversion was re - adju s ted by solv ing fo r "observed yield" in equation 4.28 . In Figure 4. 46 is a pl ot of the rate constants, k1 and k2' as calculated from the equatio ns, k, = A, exp(-E, /RT) Imi n, (4.29) and k, The solid = A, exp( -E,/RT) Imin. line represents (4.30) the observed reaction rate constant which shows that the faster reaction is that which is observed at a given temperature. features This para l lel or is as expected for a competitive reaction s. reaction mechanism which For a se ries reaction mechanism, the converse would be true,. that is, the slower reaction of the two would be observed experimentally. -I (f) 2 10 o W I- ,..-- 0 ~ z H 1 -3 0 :E , ~ kl -4 10 o -51 rb 10 250 275 300 325 350 375 400 425 TEMPERATURE, DEG. C Figure 4.46 Plot of Reaction Rate Constants. kl and kZ' vs. Temperature -'" '" 166 A noteworthy departure from previous l y proposed kerogen decomposition schemes is repre se nted by the parallel me c; hanism set f orth in this work . Series mechan i sms are common in the decomposit ion. l iterature on kerogen It is thought that t he slow heating rate used in the present study was benefic i al in resolving the two reaction s whic h~ at the usual higher heating rates employed in TGA studies and at the high temperature common in isothermal observed . kinetic studies, are not normal l y CHAPTER 5 CONCLUSIONS Batch thermal solution of He ll' s Hole Canyon oil shale in hydro- carbon solvents has been studied. Characterization of the process has included the following: • yield studies • elemental ana l ysis • carbon -13 nmr analysis of spent shal e • elemental analysis of extracted material • simulated distillation of extracted material a kinetic study. Considerably higher yields than those typical of pyrolytic processes have been observed with each of the solvents used; namely, cyclohexane, tetra ' in, and creosote oi l. Yields as high as 96 percent organic removal (123 percent of Fischer Assay oi l plus gas yield, 160 percent of Fischer Assay oil yie l d) were recorded in 24-hour run s. formation was observed in the extracti ons. temperature used in the yield studies was lower than typical 379·C~ retorting temperatures. Little gas The highest extraction which is at least 120·C The significant l y lower operat i n9 temperature wou 1d represent a s i zeab 1e energy sav i ngs over retorting processes based on kerogen pyrolysis. In l ight of the greater organic re covery possib l e as well as the benefits of lower operati ng temperature~ further study of t he thermal solution continuous, rather than batch, operation is warranted. process in 168 Elemental and carbon -l3 nmr analysis of spent shales fr om thermal solution suggested that tetra';n was slightly more effective than cyc l ohex ane in extracting aromatic portions of kerogen . Although little difference in the extraction yields was observed between these solvents in extractions of Hell's Hole Canyon shales, a significant difference in yields was observed (71.2 percent for tetral;n extraction, 50 . 5 percent for cyclohexane extraction at 364t2-C) in extractions of hi gh ly aromatic (f a- 0. 50) Antrim oil shale . Thermal solution in tetra';n may consequently be of interest in recovery of organics from oil sha les of th e eastern U.S. which normally show about 45 percent conver sion of kerogen t o oil in pyrolytic retorting . Analysis of the extracts by GC simulated distillation showed that there was a basic difference in the boiling range of the cyc loh exane and tetralin extracts. The cyc l ohexane extracts were higher.boiling and of narrow boiling range, with up between 375- and 475-C. to 54 percent of the extract boiling The observed differences in boiling range for extracts of the two so lvents was attributed in part to the different states in which the so lvents exist at extraction temperatures . Cyclohexane, above it s critical temperature of 280·C in all cases , was able to penetrate the sha le and extract fragments of kerogen, whereas liquid-phase tetral,n (Tc = 449-C) of undergone kerogen whi ch have seemed to recover primarily portions suf f icient thermolysis to become so l uble . Cyclohexane was found to be a slightly more effective so lvent (it gave somewh at higher y; e 1ds) whereas no significant difference at in temperatures be 1ow about 360·C yields obtained solvents was observed at higher extraction temperatures . with the two 169 The extract boiling-point distributions were shifted to slightly lower temperatures as the extraction temperature increased. The only except10n to this observation was 1n the case of cyclohexane extractions of shale C (62 gal / ton). these shales were The boiling point distributions of extracts of shifted to lower extraction temperature up to 365°C. loss temperatures with increasing Above this temperature, however. of l ight components and a shift of boiling range to higher temperatures were observed. This observation may be a consequence of the higher concentration of extracted organic material present in the so 1 vent whi ch wau1dine rease the 1; ke 1; hood of recomb; nat i on react 1 cns of free rad ica ls, thereby producing higher roolecular weight, h1gherboiling species. A linear -heating pa rameters bitumen. technique has been used to evaluate kinetic for the de compos it i on of kerogen to sol ub 1e (pyro lyt i c) l inear-heating runs were made in tetralin at a heating rate of O.2°C / min. dHferential The results analyses of integral, of the data differential. suggested competitive first-order reaction mechanism. the and differenceexistence of a Yield data was subsequently fit to such a model. correcting for the small amount of natural bitumen present in the sample (8.9 percent of total organic) in the analysis. By minimizing the lea st -squares res idua l between the data and the calculated conversion at the maximum temperature I of each of the 18 runs, kinetic parameters for the two pathways were found to be: E ," 20.8 kca1/mo1e A, " 2.2 x 10"/min T < 350 0C 170 E, = 45.7 kcal/mole T A, This model = 1.7 x 10 l ' /m in is unique in that it deviates from the usual consecutive decompos it i on mechan; sms this > 350 0 C model, the hypothesi zed experimental yield for kerogen convers; on. data can be reproduced Us i n9 very accurately. 5.1 More detai led Suggestions for Further Work analysis of both .cyclohexane extracts should be performed. tetralin and (supercritical) A knowledge of the types of molecular species present in the extracts woul d help to better describe the characteristics of the two types of extracts and lead to a better solv~nts understanding of the mechanism of action of the two the underlying cause of the variation of extract as well as character with extraction temperature. Additional solvents, such as a light fraction of shale oil or mixed solvents, such as tetralin and decal in, should be used to determine the effect of the solvent on the extraction kinetics. The kinetics of supercritical extraction should also be studied. It ;s felt that a major thrust of future work in the area of thermal solution should be directed toward oil shales of higher aromatic content than those of the Green River Formation. While higher yields than those possible in pyrolytic processing schemes have been observed in thermal solution of samples of Green River shales in this work, a more substantial improvement in yield over that poss ible with pyrolysis 171 is anticipated from the rrore aromatic Antrim or Devonian shales of the eastern U.S. Analysis of the extraction products of these shales as we ll as carbon -13 nmr analysis of the spent shales would be helpful in this endeavor . APPENDIX A MASS BALANCE -- CALCULATION OF YIELD A mass balance over the organic material can be written for the thermal solution process as follows: weight of organic material in raw shale (9) = weight of organic material in spent shale (9) + weight of organic material removed from shale (g). (A.l) Equation A.I may be rewritten as follows: frW r = f 5 W5 (A.2) + W oe At the rroderate extraction temperatures experienced by the shale, no inorganic decomposition was expected or observed so that an overall mass balance on the shale gives; Wr = (A.3 ) Ws + Woe • By solving for Ws in equation A.3 and substituting it into equation A.2, we get (A.4 ) A rearrangement of equation A.4 can be performed so that the yield can be calculated according to its definition; Yi e 1d or ani c removed Woe fr - f5 = ""'~'i7'7-='-=",,,-,,,,,,,,,~T7"C' ".,.,.-= ,,'-;'-7'-.organic n raw sha e I.. f (I f ) · (A.S) r r r S Values of fr and fs are determined by oxidation of a 2-gram sample of shale at 450°C. APPENDIX B GC SIMULATED DISTILLATION DATA REDUCTION PROGRAM -- "SIMDIST" Th is program converts retention time and area percent data to bo; 1i n9 poi nt and wei ght percent. res pect 1 ve ly. From the retention times and known boiling points of the components of an n-alkane standard mixture, a cubic-spline polynomial is generated by the IMSl subroutine IIICSICU". The coefficients of this polynomial are then used i n the IMSl routine "IC SEV U" t o convert the retention time of peaks of an 011 sample chromatogram to boiling poi nt. Wei ght percent 1s assumed to be equivalent to the area percent under a gi ven peak. At the users option, the prog ram may then produce any combi nation of the follow i ng as output: a boil i n9 poi nt cu rye. a table of wei ght percent cuts, or a table of bolllng pol nt cuts. The program can also take into account the we i ght percent of any solvent peaks present in the calculation of cumulative weight percent dist i lled. Up to 30 product cuts may be calculated to compare various oil samples for distillation range. A plot of boiling point versus cumulat ive weight percent distilled may also be generated. produced using several This plot is of the plotting subroutines available in the Unl vac system 11 bra ry UUCC·UUPLOT. Plott 1 ng 1s done on the Cal Camp plotter. Data is entered in the formats as listed in l i nes 114-140 of the program. The first eight dat a records are included once each time the 174 program is executed. Inclusion of the next four records is dependent on the value ass i gned to the variable rOPT specified in the first data record (line 117). unique to a 91 Yen The ne xt three data records (lines 128-130) are sample oil chromatogram and may be repeated indefinitely so that data from a number of sa mp le chromatograms may be redu ced in one exe cution of the program. A value of NOPT = 3 must be entered in the last data record. In this appendix is a listing of the program, the data input for sample 12-FA-l, and the program output (a table of boning point cuts) for that run. Fi gure 4-23. Not include d is the bolling point curve, wh ic h appears in 175 Program l ;sting ,. c >. 3. C C '. C 5. ••7. PItOGIUH ·SIHDIST" CO NVERTS RH[hlTI ON TIKI 8. 9. 10. ". 13. • DATA BPSTl36. 1 .69 •• 98 .11, 125.6,150.8.1711. ,195 .8,216.2 ,252 .5 .270.5. 287 . 5 . 303 .• 317 •• 31j~ •• 391 . , 11 32 . , 1168. ,1196 • • 525 ./ ACOLO R: ' P£Hl 111. C C C 17. c 16. 19. 20 . 21. C C C C >2. C 23. C 211. C C zo. C 27. 28. C C 29. 30. WTSA (20S) ,WTA (20S) ,BPSA (20S) ,WSTOP {)O) ,TSTOP(30) ,BP{)O ) CHA lUCTER 1 Zl ACOLOR CHARACTER- 7 RUNIO INTEGER POPT . TOPT It NUMBER 1 Bl.ACX' C 15 . 16. 25 . AREA PERCENT DATA FRO" G. C. 0] KIN SION erST ( 19 ) • US! ( 19 ) . C{ 16. 3). BPAlI ( II ) ,11151. (2OS). vr ( 30) • • ll. ~o SIMULATED DISTIllATION TO BOILING POINT CURVE c USER MUST CHOOSE AMONG THE FOLLOWIIiC OPTIONS •••• POPT (PLOT OPTION) 1 Pl.OT or BOILING POINT VS. CUHUl.AT IVE VEIGHT PERCENT DISTILl£D 2 110 PUlT TOPT (TABl.E OPTION) 1 l.lSTS SOIl.IHG POIIIT FOR A GIVEN wEIGHT PE RCENT DI STI LlED (UP TO 30). EH TER NUHBER OF POINTS ( NUH'Ii'T ) AND POI HTS DESIRED ( WSTO P __ AR RAY) 2 l.l STS W'EIGHT PERetHT DISTIl.l.ED FOR A GIVEN BOIl.III G POI NT (UP TO 3D). ENTER IIUHBER OF POINTS ( NUHl) AII D POIMlS DESIRED ( TSTOP __ ARRAY ) 3 PRlh'lS BOTH TABU 1 .A1I1) 2 /I NEITHE R TABl. E IS PRINTED 31. 32. C C C 1I0PT 33 . C 2 311. C 35. C 36. 37 . C C 38. C 1 CAl.IBRATION STANDARD OIl. SAMPl.E 3 ,.D LIST OF VARIABLES •• • •• 39 . c BPST " 0. 111. 112. C C C .rny contdning boil ing points of compon!!nts of n-Ilk .n!! st.nd.rd IIlST ,rr,y containing r!!t!!nUOn U_s of &13. C compon!!nts of n __ lk.ne .t.nd.rd 145. c c 46. .7. C C C tw o-dimension.l . r r. y cont.inln, co!!ff ici !!nts of cubic splln!! polynomi.l . D!!termi ned in ~]CSICU~. .~. 48. C 49. 50 . 51. C C C C 5>. 53. BPAR p.r.~ter . RTSA . rr.y containin g re t e nti on U.es of res olved components of 011 Ample VTSA . rr.y cont,ining wl!1&hts o f resolv.d c Olllponents of 011 aall!pll! C 511, C 55. C 56. 57. C C required 1n BPAR ( ]) tO.ltl." ~ICS]CU· . 176 58. 59. C C WT array containing calculate~ weight percent distilled for de3i r ed boiling point CUU BP Irray containing calculated boiling points for de3ired weight percent cuts 60 . C 61. C 62. 63. C C 611 . 65 . 66. 67. C C WSTOP IrnlY containing de s ired weight percent cut va lues C !STOP array containing desired boiling point cut temperatur e.:!l 68. 69. C C RUNID character value identifying run 70. 71 . C C HUH""" 72. C 73. C 711. C 75. 76. C C lER 77 . 78. 79 . C C C SW 80 . C C C SWZ weight percent of sample boiling over 525 C 81. 82. WSOLV 83. 811. 85. 86. 87. 88. 89. C C C C C C C weight percent of solvent or other undesired peaks 90. C C 91. C 92 . C 93. C 911 . C NUMT WPER number of weight percent cuts (NUMO.'T(:30) number of boiUng point cuts (NUtrr<=30) error parameter from IMSL .:!Iub\out1ne.:!l adjusted (for .:!Iolvent or other undesired peaks) wei ght percent of gi Yen peak weight pe rcent of total .:!Iample eluted from column NUMDl number of peaks (not including solvent peak) ( NUMD1(200) SPAVE weight averaged bOiling point of 5afDple WTA array containing accumulated weight percent It each peak 95. C 96. 97 . 98. C C C XSCALE 99 . 100. 101. 102 . C C C C C x-coordinate of plot, cumulative weight percent .:!Icaled to size of plot YSCALE y- coordinate of plot, boiling point size of plot C 1,ll , lJ,JJ C C C WElCiHT 103. lOll. 105 . 106. 107. 108. 109 . , 10. 11'. c 113. C C C C ,,2. C ISAVE counting variable, counts number of peak.:!l scilllle~ index variables temporary variable used 1n determlnlll10n of weight pe r cent cuts DATA ENTRy •• •• •••• Dltl IllUst be entered in the f ollowing format.:!l: to 177 1111 . 115. , 16 . 117. 118. 119. 120. 121. 122. 123. '2~ . 125 . 126 . m. 128 . 129 . 130 . 131. 132 . 133 . 13~. 135. 136. 131. 138. 139 . 1110 . 1 ~1. 1~2 . 1113. 111 11 • 111 5. 1116. 1117 . 1118 . 1119 . 150. 151. 152. 153. 1511. c c c c Tormlt.(s) POP! c c c c c c c C C C C C C C C C Oil Sample I S ,IIX ,1.7 8flO.5 I NOPT I 5 . IIX . A7 21'10 . 5 . IS 8nD .5 RUHID WSOLV WPER HUMOT \ RTSA(I) WTSA (I), I: 1. HUKDT blink repeat. list thre e lines once f or elch samp le Last En try C C C NOPT (,,3 ) 15 REA D PLOT AII D TABLE OPTION • ••• READ (5,311 ) POP! ,TOPT If ( TOPT . EO.II ) CO TO 100 If ( TOPT . £0 . 2) GO TO 200 c C C 200 100 c C "'. ' 65 . 171. RUNI D RTST(I),I:l , 19 \ BPARe!) . l:l.11 C 163 . 170 . 15 8f5 .1 15 8f5.1 C '62. 166. 167 . 168. 169 . WTS!OP (I) .I=1 , NUMWT : NUMl' \ !S!OP(!) ,I: 1. NUHl' I HOPT 155 . 156. 157. 158 . 159. 160. 161- ZI5 I NUKJT C St.andard C C C C C TOPT c C C C 10 RUD HUHBER Of WEI GHT PE RCEIIT OR BOILI NG POINT CUTS AN D DESIRED WE IG HT PERCENT OR BOILI NG POI NT CUTS •••• READ( 5,311) NU"",,1' READ( S, 36) (WSTO P( 1) ,I: 1 ,NUMlo1' ) I f( TOP T.EO. l) CO TO 100 RU D(S , 311) NUMT READ(S,36)( TSTOP ( I ) , I:l,HUHT) CONTINUE 00 10 I: 1,20S RTSA(l)",O . O COHTINUE NOP! DETERMI NES TYPE Of RUN (STAN DAR D Of! SAMPLE) W1SA(I)",O.O REA O{5, .II ) NOfT, RUNI D IF ( NOP! . EO.3) GO TO 3 00 WRItt ( 6.6) WRITE(6,6) RUNID CO TO ( .IIOO ,SOO) ,NOPT RET ENTION TI I"Z S ( ARRAY ' IITST' ) Of CAL.IBRATIO N STAN DARD ARE REA D IN AN D ECMO PRINTED. BOILI NG POIIITS Of STANDARD COMPONE NTS ARE ASSIGNED TO ARR AY • BPST' IH DATA STATE- 178 172. 173. 17'1 . 175. 176 . 117 • 118. 179. 180. 181. 182. 183 . 1811. 165. 186. 187 . 188. 189 . 190. 191. 192 . 193 . 19'1 . 1,., . C 1100 C C e C C 'ICSICU': II-tSI. SUBROUTINE USED 10 FIT CUBIC SPI.I NE POI.YNOMIAI. TO RETENTlON tIME _ BOII.ING POINT DATA 500 C C C 205. 207208. 209. 210. 211. 212. 213. 21'1. 215. 215. 217. 218. 219 . 220. 221. 222. 223 . 22'1. 225. 225. 227. 228. CAI.I. IeSI cue RTST ,BPST , 19 ,BP AR. C. I 8 ,IER) GO TO lOa SW= O. SWZ=O. INPUT WSOI.V . WPER, NUHD1 •••• READ ( S,25) WSOI.V . WPER , NUHDT WSOI.V=WSOI.V/l00. C e C 195. 197. 198. 199. 200. 201 . 202. 203. 2011 . 2". MEN! READ{S , 111){RTST(I),I=l , 19) READ{S , I 'Il (BPAR{J) ,J;: 1, 'I) WRITE{5,2) WRITE(5,18) WRITE(5 ,1I2) IiR ITE( 5,115) (BPS1( I) ,R1ST( I) , I;: 1,19) 800 700 20 C C C C 500 C C C 30 C C ASS IGN VAlUES OF SAMPI.E RETENT ION TIMES AND WEIGHT PERCENTS TO ARRAYS RTSA AND WTSA •••• READ{S " I1){RTSA(I),WTSA{I) , I=',NUHD1) DO 20 1,,1 , 200 WTSA{I)=WTSA{I)/{WPER_WSOI.V) ISAVE= 1- I IF(RTSA{I) . EQ . O.) GO TO 500 SW=SW+WTSA( I) .W?ER IF(RTSA(I).GT . R1ST{19ll GO TO 700 IF(RTSA{l).G'T.RTST( 1» GO 10 600 GO TO 20 WTA( I):Sw GO TO 20 swZ:SWZ+WTSA(I).WPER GO TO 800 COh'TINUE 'I CSEVU': IMSI. SUBROUTINE TO CONVERT SAMPI.E RETENTION llMES TO BOII.ING POINTS CAI.I. I CSEVU( RTST , BP ST , 19 ,C, I 8 ,RTSA, BPSA , ISAV E ,lEft) CAl.CUI.ATE BPAVE •• •• BPAVE:O. DO 30 I=l,ISAVE BP AVE: BP AVE/ 100 . IF(POP1.EQ.2) GO TO 1000 BPAVE:8PAVE..WTSA(I) · BPSA(I) ' IDPLOT' INITIAlIZES PI.OT OF DESIRED SIZE (I.IBRARY ROUTI NE ) C CAlI. IDPI.OTC8.S , " . ) C C 'DRAWAX' ORAWS AND I.ABEI.S AXES 179 229. 230 . 231. c CALL DRAWAX CRUIiID ) 00 110 I:l.ISAV£ XSCALE"WT A( Il 120. YSCAL.bBPSA ( I )/ 100. 23Z. 233. 2311 • 235. 236 . 2 37. 238. 239 . 2110. 211,. 2112. 2113. 21111. 2115. 2116. 2117. 2118 . 2119. 250. 251. 252. 253 . 2511 • 255. c C C C C c 'POINT' PLA CES DATUM POINT AT COORDINATES (XSCAL £ ,YSCAL£) WHICH ARE THt CUMtn..ATIVE WE IGHT PERCE NT DI STI LLED AN D THE BOllING POI NT . SCALED TO THE SIZE OF THE PLOT 110 C C 1000 C C C 256. 258 . c C 2711. , 300 277 . 278. 27'. 280 . 281. 282. 283 . 2811. 285. CALL FINI CONTINUE OUTPUT FOLLOWS •••• WR l TE ( 6.2) WRITE(6 , 22) ISAV E ,SW.SWZ \o'RlTE(6 , 2) WRITE ( 6.211 ) WRlTE ( 6 , 26) WRIT£ ( 6,28 ) WI! ITE ( 6, 32) ( RTSA ( I l , BPSA (I) , WTA (I) ,1: 1,ISAV£ ) WRI1£(6,2) WRITE( 6 , I!II) 8PAVE IF(TOPT.EQ.4l GO TO 100 If (TO PT.£Q.2 ) GO TO 1100 WR ITE(6 , 8) WRITE( 6 ,12 ) RUNID WRITE{6 , 2) WRITE { 6,38) WRIT£ (6 , 1I2) wrICiHT: O. JJE 1 DETERMINE BOILING POINT fOR DES IRED wrIGHT PER C£NT CUTS •• , . 00 50 II: 1 , ]SAVE 273 . 275. 276. 'flNI ' TERM I NATES PLOTTING (LIBRARY ROU TINE ) C 257. 259. 260. 261. 262 . 263 . 2611. 265 . 266. 267268 . 269 . 270 . 271. 272. CALL POI NT ( XSCAL E ,YSCALEl CONTINUE 50 1200 1100 C C C wrI GHTE wt IGHT+WTSA ( II) ·WP£R IF{ILEO.ll GO TO 50 If (JJ ,GT.N UI1oI'Tl GO TO 1200 IF(WEIGIfl" .a: , WSTOP(JJ)) GO TO 1300 GO TO 50 BP ( JJ l EBPSA CII- ll +( BPSI.. ( II ) - BPSA (II- 1) ) . ( ( WSTOP( JJ) • _IiTA ( Il- l )) 1 ( WTAn Il - IiTA ( 11- 1»)) WRITE ( 6 •.116 ) WSTOP( JJl • ap ( JJ) JJEJ J+l CO NTIN UE I F ( TOPT .£O.ll GO TO 100 CO NTINUE PRINT TABlE Of CUTS .. .. 180 181 3113. A2:'Q""I,JL AlIVE WEIGHT PERCENT ' A3=' IIUH HO. '// 10 3/111, 3115. 311 6. C CALL P[.01(2.5.3.5.-3) CAU. sYMBOL{1 . 0 ,-' . 3 , .21 ,A3 ,0.0.15 ) CALL Sf IiBOL( 0.8 , - 0.611 ., , 11 ,A2 ,0.0,25) CAL.L PLOT(0.O,O.0.3) YA=-.25 3117. 3118 . 3 119 . 350. 351, 352 . C 00 100 1=1,6 XA=-l. ,.FLOAl( Il 353. 35i1 • 355 . XA:XA-.8 IF' n.EQ.n XA:-.95 IF (I.EO . 6) XA:Ii.15 356. 357. 358. 359. 360. lHUI1=O. (l-1) · 20 CAlL H U ~III(XA.YA,,'.IHUH.O 100 C CALL PLOT(0 . O,O.0. 3) 361- 3". 363. c 3611. CA1.L PLOT(S .,O.,2) DO 11 0 l:::l,tI XT: 5 . O-FLOJ.T( 1) 365 . CAlL PLOTCXr,O.o ,) 366. 367. 368. 369. . O) COIv'TINUE C 11. CALL PLOnX! , 0.1 .2) CONTINUE 370. CALL STI1!DL( -0.5 , ' .90 • • ' lI,Al .90 . 0. 16) 371. CALL PLOT(0 .O,O . 0 . 3) 372. 373. XA:-.15 C 374, 376. 00 120 1::1 . 7 Tb _l.1S+Fl.OAT( I) YA.=TJ...O.7 377 . IF 378 . INUH=O+ ( I-" ' lOO CALL NUMBRI(XA ,YA, . , , IHUM, 90.0) CO NTIN UE 375. 379 . 380. 381382. 383. 3811 . 385. 12. CAL L PLOT(0 ., O.,3) CALL PLOTt O. , , • , 2) C 387. 388 . 389 . 13. 391392. 393 . 3911 . C 395. C no DO 1:o'.S YN:fLOAT(I) CALL PLOT(O .' ,YH,2) CALL PLOT( O. O,YN, 3) CALL PLOT( 0.0 ,TN.' ,2 ) COh'TINUE CALL PLQT(S.O ,6 . 0,2) CALL PLOT(S.O,O.O,2) CALL PLOT(0 . O,O. O,3) RETURN END 396 . 397 • 398 . 399. .EO.n YA:-.95 C 386 . 390. (I C C 182 1100. "01. 402. SUBROUTINE POINT(X ,Y ) C "03. C C SUBROUTINE TO Pl.ACE DESIRED SYMBOL AT COORDINATES (X,Y) 40". CAJ..L SYMBOL(X,Y,.100,5 , O. ,_2) R£nJRN 406 . END '05. 183 Input Data for Sample Run ' OAn,n. TElV' . .. DATA U8Jtl 37 ]/'OD 07/11/ 83 10:35: 13 to} 2 2 2. 5 ,. ••5. , 200.0Z75 . 0375 . 0~25.D_70 .0 6. 10.095 7. 2'1.7815 ,.•• 10 . ". 12. 13. ". 15. 5T.l 3D .2 875 2 " . B153 00. 17 00 .'" ". 25 . 26. 27. 28. 29. '0. ". ". 32 . 33. [ND DATA. 'fIN 2 .9275 ".115 13 .4725 1&1 .285 16 .22 1J7 26.95 '2~fA_ 00 .169 00. 150 " 00.27 00 . 329 00.53 00.2116 00.099 00. '1)5 01.7 1 OO.II SO 00 .7110 00 . 58) OS.21 00.1130 00.662 06.59 07.89 09.17 10.38 12.11 13 .59 111.57 15.8 3 17.77 18.81 20.98 22.31 211.63 2'6.55 01 . 3811 02 . 698 01.1102 01.719 01.2311 02 .237 00.997 01.165 01.953 02 .8116 02 .5011 02 .205 00.031 , 7 .5 9 22.33 1 , .0 01.35 01.95 OZ . 99 ()ij.17 5.8075 19 . 5125 28.875 00 . 95 03.55 22. 23. 1.73 00 .II S7 m .53 21. .9 125 12.51 00, 11611 16. 20. 11,175 00.76 01.17 H. "." . ." 00.61111 00.769 00.32 00 .61 01.05 01.117 02.011 00 .21 1 00.31 00 . 237 00 .259 00 .,, 00 .259 00.218 01 .' 3 00.)09 00.1130 00 .7S1 01 . 62 00.1 611 02.110 00.519 00.5110 03.17 00 . 7111 03.31 00. 313 0).81 00 .737 ~.oo 00. 311 9 0/1 • .111 00.386 00.565 011.70 05.05 05.59 06.8) OO.BSO 00.7911 06 .16 00 . 6'16 00 .905 00.539 00 .6115 07.06 00 . 756 08 . 13 09.69 10.73 12 .57 13.75 15 . 01 16.]7 18.03 19.57 21.35 22.93 25.13 00.257 00 .J19J1 00. 27J1 01.1185 00.727 00 . 8113 02.317 02.083 03.169 00.129 03.132 01.5116 08.29 10 .01 10.99 12.67 111.03 15.119 16.92 18.n 20.28 21.67 23.56 25.57 OO.77J1 01.556 00.799 00 . 11111 00.938 01.1167 01.062 00.783 02.1191 01.829 02 . 698 01.759 07.62 08.58 10.23 11 .11 8 12.93 l J1. 31 15.69 17 .21 18.58 20 .58 21.95 211 .10 26.16 03.68 06.113 01.097 00 .872 oo . /lOJI 01 .909 01.89" 00.7711 00.7111 01.888 00.083 00. 137 01 . 029 02 . 11111 00.631 184 Samp 1e Output ••••••••••••••••••••••••••••••••••••••••••••••••••• 1V'fri Kl. ST . A 3D 8P,C 36.10 69.00 98.&1 0 125.60 ItT,MIN ... .29 .91 150.80 1.73 2.93 17&1.00 11.115 195.80 5.81 7.59 216.20 252 .50 270 . 50 287 .50 10.' 0 30).00 1].117 317.00 111 .28 311'1.00 16 .23 '9 .5 1 " .17 12 .5 , 391.00 1132.00 22 . 33 .1168 . 00 2&1 . 79 IIg8.00 26.95 525.00 28.88 185 ................................ " ........•........ RlIN I(). lZ_FA- l " I 'li'ARliIl/v ERIIOR I(). (IER:;: POINTS= 89 SUH OF WTS.:1 00.00115 \IT. PCT. OVER 525Cz . 0000 CU H. RT ,HIN . 170 . 270 .320 . 370 • tll0 .5 30 .610 .710 .760 . 950 BI'.C 1 ~ .8~ ,ODD 42.16 51.27 58.20 .8011 75 . 35 83.30 90.19 92 .71 99.66 1.050 103 . 07 105 . 82 l OT ••n 1. 350 --.000 32.83 1.130 1.170 WI' .PC! 113.111 117.1111 1.1170 1.620 1.7 10 122 .27 125 . 01 1.098 1.268 1.5118 1.816 2.0611 2.590 2.703 2.996 3.3117 3.900 4.393 'L8Bl 5.061 5.612 , . 950 131 . 60 6.1184 2 . 0100 2 . 1100 , 33 .83 7.370 U11.50 2 . 530 2.990 11111.05 7.959 8.799 151.19 1511.60 9.411 10.252 3.310 156 .7 11 3 .550 160 .311 10.607 3.680 162 .27 3 . 870 165 .10 11.701 12 .5113 4.000 167 .04 169.62 173 . 36 178.08 183.92 186.57 192.61 200 . 1111 203.63 205.112 208.02 210.115 216 .5.11 219 . 73 222 .73 2211 .82 228.76 237 ./11 245.68 12.939 13 .427 14.068 111.801 15.1112 16.163 17.128 18.155 18 .887 19.617 20.518 21 . 376 22.620 211.191 2.11.1182 25.361 26 .350 29.411 29.972 3 .170 4.110 Q.1I10 11 . 700 5 . 050 5 . 210 5 . 590 6.160 6 • .1130 6.590 6.830 7.060 7.620 7.890 8.130 8.290 8.580 9.170 9.690 11.269 33) FIIOH 1MS1. ROUTINE ICSEVU 186 10 . 010 10.230 10 . 380 10 .730 10 . 990 11 .480 12. 110 12.570 12.670 12.930 13.590 13.750 14 . 030 14. 310 1 ~.570 15 . 010 15 . ~9 0 15 . 690 15.830 16.37 0 16.920 17 .210 17 . 170 18 . 030 18 . 370 18.580 18.810 19.570 20.280 20 . 580 20.980 21.350 21.670 21.950 22.310 22 . 930 23.560 24.100 24 . 630 25 . 130 25 . 570 26.160 26.550 251.011 25~ .84 257 . 46 263 .48 267.71 274.64 282.3Z 288.35 289.80 293.83 305.06 307.87 312.74 317 .40 321.117 327 .8 5 334 . 33 336.94 338.71 3115.87 353 . ]8 357.115 365 .115 369.23 374.20 371.28 380.67 391.84 1102.19 406.511 412 . 34 417.70 422.35 426 . II~ 1131.71 440.85 450 . 16 458.08 465 . 75 472.84 478.98 1187.12 1192.118 31.737 3Z . 195 33.786 311 .097 35.003 37.169 39.120 110 .805 111.305 113 .11511 1111 . 8511 115.679 11 6.7113 47.621 50.159 51 . 116 52.780 53 .621 5'1 .752 57.381 58.586 60.728 6Z .050 611.1113 65 . 302 65.396 67.612 71.207 711.034 74.189 71.418 77 .5611 79.6110 SO.807 83.6118 87.202 90.263 93.002 95 .504 97.258 99 .253 99.969 l00.0OS AVE B.P.=313 . lil C ••••••••••••••••••••••••••••••••••••••• •••••••••••• JlUN NJ. 12_FJ...1 BP . C VI' PCI' 200 . 00 18.10 275.00 37 . 26 65.33 375 . 00 1125 . 00 eo.1I0 1170 . 00 96.55 NO FILE OPEN APPENDIX C RAW DATA FROM THERMAL SOLUTION EXPERIMENTS In this appendix. tabulated. tetral;n, Data raw data from all fro m constant-temperature and creosote oil respect ive ly. Table '-4 . thermal runs in runs are cyclohexane. are listed in Tables C.l, C.2, and C.3, Data from l ine ar-heat ing runs in tetral;n are given in Tables C.S and Cw6 contain the raw data for runs in which the solvent/shale ratio and the particle size, varied. solution respectively. were In addition to the run identification, the tables include the constant or maximum extraction tempe rature of the run. the fractional organi c content of the sha 1e sample use d. the we i ght of raw sha 1e charged to the autoclave. the weight of solvent-free shale after thermal so 1uti on. the fract i ana 1 organ; c content of the spent sha 1e, and the calculated extraction yield, as percent of original organic removed. Additionally, Table C.5 lists the volume of solvent and solvent/shale ratio used in each run, and Table shale sample used. e.6 lists the particle size of the 188 Tab l e C. l Raw Data from Cyc l ohexane Runs Volume: 500 ml Time: 24 hours Run 10 T(OC) 7- C-2 8- C-2 9- C-2 10- C-2 fr Wr Ws fs Yiel d 300 320 354 364 0.11 3 0.113 0.113 0.113 67 . 719 73 .421 69.660 74 . 681 62 . 873 66.650 61. 900 66.605 0.0586 0. 0356 0.0159 0. 0133 51.1 71. 0 87.3 89. 4 C- 6-A 3-C -l 5- C-l l-C-l 2- C- l 4- C- l 320 325 340 343 350 375 0.197 0.1 97 0.1 97 0. 197 0.1 97 0. 197 69.770 68 . 587 69 . 620 70 . 080 73 . 493 73 . 372 64 . 520 62 . 624 60 . 660 63. 11 5 61.355 55.351 0.1300 0.1 271 0.1008 0. 0880 0. 0757 0. 0253 39. 1 40.6 54.3 60 . 7 66.6 89 .4 19-C- 3 20 -C- 3 17-C- 3 16-C-3 15-C-3 14 - C-3 12- C-3 289 305 324 355 358 373 380 0. 379 0.379 0.379 0.379 0. 379 0. 379 0. 379 68 . 577 69 .1 87 71 .1 77 71.767 69.858 70 . 709 71. 735 57.789 48. 790 49.183 46. 764 44.834 43. 956 48.332 0. 2639 0.1 728 0.1019 0.0574 0. 0700 0. 0622 0. 0815 41. 3 65 . 8 81.4 90.0 87 . 7 89 . 1 85 .4 Ext r. (%) -- 189 Table C. 2 Raw Data from Consta nt-Temperatu re Tetralin Runs Time : 500 ml 24 hrs Run 10 T(OC) 6-T -L Va 1ume: Extr . Yie ld fr Wr Ws fs 27 4 0.113 67.763 65.281 0.0893 23 . 0 3-T -L 299 0.113 69.780 65 . 472 0.0682 42.5 2-T - L 326 0.113 70.293 65 . 625 0.0489 59 . 6 4-T -L 336 0 .11 3 69 . 069 63.154 0 .0420 65 . 6 5-T -L 351 0 . 113 70 .101 60 . 349 0.0282 )) .2 I-T - L 379 0. 11 3 67.079 60 . 018 0.0117 90 . 7 5- T-M 298 0.197 68 . 883 61. 921 0.1459 3-T -M 324 0 .197 67.538 59.098 0. 1236 30.4 42.5 26 -T-M 326 0.197 70 . 515 59.940 0.1285 40.4 4-T -M 338 0.197 69 .387 61.484 0.1010 54.2 2-T -M 345 0. 197 70.108 58.350 0 .0762 66.4 I-T -M 370 0.197 68 . 709 55.282 0.0353 85 .1 3-T - R 286 0 . 297 70 .1 22 60.387 0 . 2164 34 .6 5-T- R(2) 298 0.297 69 . 882 57 . 822 0 . 2097 37.2 25-T-R 320 0 . 297 72 .041 60 . 847 0.1980 41.5 4-T -R 323 0.297 69.926 56.297 0 .1 265 65.7 I-T- R(I) 335 0 . 297 71 .875 52.255 0 . 1307 64.4 2-T - R(2) 349 0.297 70 . 205 46.4 78 0 .0710 81. 9 I-T-R (3) 375 0 . 297 70 . 269 42 . 861 0.022 1 94 . 6 (%) 190 Table C.3 Raw Data from Creosote 011 Runs Volume: 500 ml Time : 24 hours Run Extr. T(OC) fr Wr Ws fs Yie l d 10 CR - 5R 300 0 . 297 70 . 453 62.0 15 0 . 215 35.2 CR-1R 325 0.297 69 . 358 55 . 480 0 . 123 66 . 8 CR-4R 350 0 . 297 70 . 884 48 . 253 0.0 121 97 . 1 CR - 6R 375 0 . 297 71.655 51.808 0 . 0587 85 . 2 (%) 191 Table C.4 Raw Data from Tetra lin Linear-Heating Runs Volume: 500 ml Heat; n9 Rate: Run 10 17-T-5 26-T-5 10 -T-5 20-T-5 12-T-5 16-T-6 19-T-5 9-T-5 18-T-5 11-T-5 14-T-5 2-T- 5 1-T-5 6-T - 5 15-T-5 8-T-5 25-T-5 22-T-5 24 -T- 5 21 -T-5 17-T-5 0.2·C /mi n Ma x. T('C) fr Wr Ws fs Vi el d 287 288 298 316 320 327 330 338 345 351 353 359 367 369 374 382 385 388 397 405 410 0.257 0. 257 0.257 0. 257 0.257 0.257 0.257 0.257 0.257 0. 257 0. 257 0.257 0.257 0.257 0. 257 0. 257 0. 257 0.257 0. 257 0.257 0.257 70.305 70 .148 71 . 072 69.454 70.510 70 . 426 69.418 70 . 638 70.2 12 71.300 70 . 573 72.341 70.260 71.080 71.544 70.452 71.443 70.104 70 . 412 69 . 499 70 . 938 67.421 68.002 68.143 65.829 65 . 735 67.411 65.720 65 . 419 63.025 65 . 528 65 .1 97 64.831 60.185 60.734 60.221 59 . 490 63 . 517 53.206 54 .1 58 52 . 027 52.093 0. 2382 0. 2434 0.2393 0. 2261 0. 2228 0. 2335 0.2080 0.2080 0.180 1 0. 1908 0.1904 0.1741 0. 1489 0. 1384 0.1211 0.0992 0. 1217 0.0473 0.0504 0. 0225 0.0163 9.5 7. 0 9. 1 15. 5 17 .1 11.9" 24. 1 24 . 1 37.3" 31.8 32 . 0 39 . 1 49. 4 53 . 6 60 . 2 68 . 2 59.9" 85 . 7 84.7 93.3 95 . 2 a anomo l ous datum - not inc luded in ki neti c analysis. (%) Table C.5 Raw Data from Variable Solvent/Shale Ratio Ru ns So lvent: Tetralin 24 hours Time: Run Extraction ID T( OC) T-I-I0l T-I-I02 T- I-104 T-I-106 T- I-109 342 344 343 344 342 Sol vent Vol ume(ml ). 310 154 74 432 650 So l vent/ Shale fr Wr 4:1 2:1 1: 1 6: 1 9: 1 0.297 0.297 0.257 0.297 0. 297 70.169 70 . 085 70.049 70 .097 70 .054 Ws 56.208 57.175 59 . 814 55 . 639 55 . 633 fs Yiel d 0.1400 0.1500 0.1437 0.1341 0.1381 61.3 58.4 51.4 63.5 62.3 (%) <D N 193 Ta ble C. 6 Raw Data f rom Var i abl e Pa rticle Si ze Ru ns So l vent: Tetrali n Time: 24 hours Volume: 288 ml (4: 1 sol vent /shale rat i 0) Ru n lD Ext r . T(·C) Partic l e Size fr Wr Ws fs Yie l d (% ) T-1-C 357 +8 0.257 70 . 0JO 51. 963 0.0607 81.3 T- I-l-I 359 - 8+28 0.257 70 . 028 51. 623 0 . 0516 84 . 2 T-I-F 356 - 28 0 . 257 70 . 798 52 . 901 0 . 0821 72.2 APPENDIX D ELEMENTAl ANALYSIS DATA Elemental analysis data is tabulated in this appendix. Analyses of organic residue that are r epo rted we re run on the Perkin-Elmer 240B elemental analyzer at a combustion temperature of 450·C. tempe rature of 950·C was used for all A combustion extract elemental analyses. Included in the tables are the sample identification; the constant or maximum extraction temperature; the weight percent of ~it ro ge n, carbon~ hydrogen 9 and ash ; and the ca lculated hydrogen-to-carbon and nitrogen- to-carbon atomic ratio s. Extract analyses also include the combined oxygen and sulfur content determined by difference. Data for the organic constant-temperature residues runs are respectively. Table 0.3 1 ists re sidues linear-heating from fr om cyclohexane listed the runs in Tables re su lts of in tetralin. analyses are tabulated in Tables 0.4, 0.5, and 0.1 analyses Extract tetralin and 0.2, of organic elemental and 0.6 for cyclohexane, tetral in constant-temperature. and tetral i n 1 i near-heat ;ng extract ;ons. respectively. Data footnote. in Table 0.3 judged to be inaccurate are indicated by a Those data were not considered in the discussion of trends, since they represented an anomalous departure from the other data . In the case of data from run s TT-21 and TT-17, the sma ll amount of organic material remaining in the spent shale is believed to be the cause of the ; na cc uracy. 195 Tab l e 0. 1 Elementa l Analysis Results: Residues of Cyclohexane Extractions Run 10 N/C Ext ract; on Temp . ("C) %C %H %N % Ash H/C 7- C- 2 300 3.55 0.47 0.05 95 . 24 1. 592 1. 196 8-C - 2 320 2. 10 0.27 0.04 96 . 66 1. 535 1. 736 9- C- 2 354 0.75 0.09 0.01 98 . 44 1..420 1. 884 3-C -1 325 9 .1 7 1.1 7 0. 14 88 . 91 1. 531 1.507 5- C-1 340 6.95 0 . 81 0.14 91.88 1.405 1. 776 1- C- 1 343 7. 14 0.81 0 .1 6 90.04 1.365 1.892 2- C-1 350 4.2 1 0.50 0 . 08 94.56 1.434 2 . 016 4- C-1 375 1.81 0. 16 0.04 96 . 20 1. 062 2.230 19- C- 3 289 20. 15 2.48 0 . 43 74.46 1.476 1. 851 20 - C- 3 305 13 . 42 1.60 0.34 82.22 1.429 2.1 52 17-C - 3 324 8.96 0 . 99 0 . 30 88.56 1.331 2 . 921 16- C- 3 355 4.91 0.37 0. 15 93.52 0.893 2 . 603 12 - C- 3 380 6 . 31 0 . 38 0.26 92.43 0.725 3 . 562 (xlOO) 196 Table 0.2 Elemental Analysis Results: Residues of ConstantTemperature Tetralin Extractions Run 10 Temp. ('e) %e %H %N % Ash HIe N/e (x100) 6·T·L 3· T·L 2· T· L 4·T·L 5·T · L l·T· L 274 299 326 333 351 379 6.53 4.77 3.59 2.84 1.88 0.96 0.84 0.59 0.50 0.44 0.30 0.17 0.13 0.09 0.06 0.07 0.06 0.05 90.13 93.64 94.04 95.75 97 . 22 98.16 1.549 1.489 1.690 1.872 1.903 2.090 1.653 1.563 1. 375 2.234 2. 706 4.111 5· T·M 3·T·M 26·T·M 2.T.M(2) l·T·M 298 324 326 331 370 10.02 8.94 7.27 6.20 2.34 1.30 1.20 1.00 0.78 0.28 0.26 0. 12 0.15 0.12 0. 03 87.30 89.13 89.39 92.79 96.17 1.560 1.617 1.650 1.518 1.426 2. 229 1.160 1.830 1.632 1.282 3·T·R 5·T. R(2) 6·T·R 2·T·R(2) 1·T. R(2) 1·T. R(3) 286 298 318 349 360 375 15.21 14.10 14.16 9.24 4.99 0.98 2.00 1.94 1.87 1.28 0.72 0.18 0.34 0.28 0.29 0.18 0.10 0.05 79 .99 81.99 81.48 86.81 92.91 97.54 1.579 1.648 1.585 1.655 1.722 2.161 1.933 1.711 1. 737 1.698 1.718 4.447 Extraction 197 T"ble D.3 Elemental Analysis Results: Residues of LinearHeating Tetralin Ext ract ions Run ID TT-7 TT-IO TT-20 TT -12 TT-16 TT-19 TT-9 TT-18 TT- ll TT-14 TT-2 TT-1 TT-15 TT-8 TT-25 TT-22 TT-24 TT-21 TT-17 Max T (OC) %C %H 287 298 316 320 327 330 338 345 351 353 359 367 374 382 385 388 397 405 410 17. 27 17 .33 16.94 15.89 16 .01 15.71 15.43 14.69 13.97 13.10 12.29 10.56 8.81 7.64 9.5 3" 3.12 3.80 1. 34 0.91 2.15 2. 17 2.25 2.04 2.10 1.97 1.99 1.79 1.80 1.69 12.53 1.37 1.14 0.98 1.17" 0.40 0.49 0.22" 0.15" a data judged inaccurate %N 0.44 0.38 0. 39 0.40 0.40 0.41 0.37 0.24" 0.35 0.31 0. 16" 0.23 0.28 0.14 0.31" 0.08 0.13 0.07" 0.04" N/C % Ash H/C (x100) 77.42 77 .81 79.24 79 .94 79.57 80.73 81.26 81.25 83 .14 84.17 84. 87 87.63 87.06 88 .93 88 . 24 96.42 94.16 97.90 98.20 1.491 1.501 1.593 1. 543 1.575 1. 505 1.550 1.462 1. 542 1.549 1.494 1.554 1.549 1.540 1.478 1.530 1.556 2.003" 2.037" 2.184 1.879 1.963 2. 163 2.123 2.229 2.066 1. 389 " 2. 166 2.009 1.092" 1.830 2.733 1.609 2.824 2. 249 2.840 4. 279" 4.253" 198 Table 0.4 Elemental Analysis of Cyclohexane Extracts Run ID Extraction Temp.(OC) %C %H %N %D+S' H/C N/C (Xl00) 7- C-2 300 80 .14 11.02 1.61 7. 23 1. 650 1.7 22 8- C- 2 320 81.29 11.51 2 . 08 5 . 12 1. 699 2. 193 9-C- 2 354 81.79 11 .39 2. 11 4 . 71 1.671 10- C- 2 364 81 . 41 11.59 2.03 4.97 1.708 2 . 211 2.137 3- C-1 325 78.96 10.86 1.58 8.60 1. 650 I. 715 5-C - l 340 79 . 39 10.97 1. 72 7 . 92 1. 658 1. 857 6-C- 1 362 79 . 83 10.97 2.10 7.10 1. 649 2 . 255 4-C-l 375 79.93 10.77 2 . 24 7.06 1. 617 2 . 402 19-C-3 289 81.60 10.47 1. 88 6.05 1.540 1.975 20 - C-3 305 82.64 10.70 1. 78 4 . 88 1. 554 1. 846 17-C - 3 324 82 . 28 10.87 1. 82 5.03 1. 585 1.896 16- C- 3 355 83.29 10.85 1.99 3 . 87 1.563 2 . 045 15 - C- 3 358 83 .1 5 10.49 1. 97 4. 38 1. 514 2 . 031 14- C-3 373 84 . 88 10 . 60 2. 16 2 . 36 1.500 2. 181 12-C -3 380 84.80 10 .71 2 .1 8 2 . 31 1. 516 2 . 204 a determined by di fference 199 Table D.5 Elemental Analysis of Constant-Temperatu re Tetral;n Extracts Run 10 Extraction Temp.(OC) %C %H %N %D+Sa H/C 2-T-L 326 83.77 10.20 0.58 5.4; 1.461 0.692 4-T -L 333 85 .53 10.25 0.71 3.51 1.438 0.832 5-T -L 351 85.26 10.23 0.84 3.67 0 . 983 1-T -L 379 85 . 74 10.34 1.04 2.88 1. 440 1 .447 4-T -M 338 81. 74 10.52 1. 37 6.37 1.54 5 1.673 2-T -M 345 83.01 10.38 1.43 5.18 1.501 1. 718 I-T -M 370 85 . 21 10.27 1.13 3.39 1.44 7 1.333 3-T - R 286 85 .1 7 10.24 0.61 3.98 1.443 0.714 5-T - R(2) 298 82 . 89 10 .29 1.10 5.72 1.489 1.322 6-T - R 318 82.17 10.42 1. 67 5 . 74 1.522 2 .030 4-T- R 323 81.77 10.27 1.09 6 . 87 1.507 1. 328 2-T-R(2) 349 85.94 10.32 1.40 2.34 1.448 1.633 I-T-R (2) 360 85.20 10.28 1. 29 3. 23 1.441 1.509 I-T -R(3) 375 85.59 10.30 1.95 2.16 1.444 2.277 a determi ned by di fference N/C (.IOO) 1.215 200 Table 0.6 Elemental Analysis of Run \D l inear ~ Heatin9 Max. T Tetra l ;n Ext ra cts %N %0+5a 10.83 1. 70 79.53 9.78 298 81.59 12-T-5 320 9-T - 5 N/C H/C (XIOO) 7.52 1.625 1.823 1.70 8.99 1.476 1. 832 9.98 1. 30 7.13 1. 468 80.03 10.51 1.74 7.72 1.5 77 1.366 1. 864 338 81.63 10.56 2.09 5.72 1. 553 2 .195 18-T- 5 345 83 .60 10.28 2 . 09 4.03 1.476 2 .143 11-T- 5 351 84 . 39 11. 35 2.22 2.04 1.614 2.255 .14 -T-5 353 84.24 10.50 2.20 3.06 1.495 2 . 239 6-T - 5 369 81.50 10.98 2.40 5. 12 1. 616 2.524 15-T -5 374 81.46 11.00 2.10 5.44 1.621 2.210 8-T -5 382 82 . 36 11. 60 2.58 3.46 1. 689 2.685 25- T- 5 385 76.63 9.58 2.26 11. 53 1.500 2 . 528 22 -T-5 388 83.38 12.11 2 . 86 1.65 1.743 2.940 24 -T-5 397 84.53 9. 98 2 .57 2.92 1. 476 2.606 17 - T- 5 405 83.20 10 .51 2 . 51 3.78 1.515 2.586 ( ·C) %C 7-T - 5 287 79.95 26- T-5 288 10-T-5 a determined by d; fference %H APPENDIX E GC SIMULATED DISTILLATION OATA In this appendix are tabulated the results of simulated distillation by gas chromatography of cyclohexane and tetralin constanttemperature extracts. cuts determined for temperature 470·C . cuts Also are 1 isted Listed in Tables E. 1 and E.2 are the temperature each extract listed; are the by namely. run the program "SIMOIST." 200·. 275-, identification. 375'. the temperature, and the average boiling point of the extract. 425'. Five and extraction 202 Table E.I Simulated Disti ll ation Results for Cyc l ohexane Extracts % Boiling Bel ow 275°C 375°C 425°C 420°C Ave. BP 0.04 0.58 1.11 1.61 10.90 16. 24 30 .43 32.77 44.18 48.51 57 . 86 56 . 88 64 . 91 68.31 75.32 78 . 87 86 . 73 86.11 88 .1 8 90.93 3B6 376 348 343 325 340 362 375 0.11 0.16 0. 49 0. 95 11.1 3 12.59 14.29 22 . 77 38.40 41.97 47.86 52 . 48 54.88 57.17 66 . 20 71.51 74.69 75.50 86 .87 86.73 401 396 378 362 275 289 305 324 355 358 373 380 0. 55 1.22 2. 7B 2.23 10.40 6.3B 8.60 0. 33 9. 87 15.92 13.98 18.29 40 . 84 61.49 52.57 30 . 53 33 . BO 45 . 89 41 . 66 47.72 68 . 21 84.50 78 . 31 62 . 74 68 . 92 70.69 62 . 16 65 . 15 82.25 92.84 90 . 22 82.35 89.21 86.B6 83 . 92 81.97 93.61 96 . 69 97.6 1 91.41 390 375 386 371 317 279 292 339 Run Extr. ID T(OC) 200°C 7-C-2 8-C -2 9-C -2 10-C-2 300 320 354 364 3-C-I 5- C-I 6- C-I 4- C-I 18-C-3 19-C-3 20 -C-3 17-C-3 16-C-3 15-C-3 14-C-3 12-C-3 203 Tabl e E.2 Simu l ated Distillation Results for Constant-Tempe rature Tetralin Extracts Run 10 % Boilin9 Bel ow Extr . T(·C) 200·C 275·C 375·C 425·C 470·C Ave . BP 2-T-L 4-T -L I-T-L 326 333 379 0.37 0.03 0.47 6.64 ID . 70 15.01 19 . BB 23 . 25 35 . 70 74.23 78 .02 76 .15 95.89 91.20 89.68 376 391 383 4-T -M 2-T -M I -T-M 338 345 370 0.02 0.11 0.38 1.79 5.78 9.54 17.59 25.09 35.37 59 . 46 64.75 72 . 21 80 .83 80.86 86 . 24 420 409 390 3-T - R 5-T-R(2) I-T- R(I) 2-T - R(I) 2-T- R(2) I-T- R(3) 286 298 335 338 349 375 0.38 2.81 0.89 0. 97 1.40 0.58 7. ID 8. 29 13. 54 11.21 18.22 13 . 97 21. 98 20.58 34.30 30 . 31 28 . 86 38 . 84 71.37 79.77 69 . 40 70.41 80.35 74 . 27 90 . 71 91. 24 82.97 84. 33 95.20 BB . 97 405 392 392 396 371 383 APPENDIX F FUNCTION MINIMIZATION PROGRAM -- "FUNMIN" This program finds a minimum of a function of n variables using the method of Nelder and Mead (1965). Fischer and R. The FORTRAN code was written by P. E. J. Bezama (19 81) and adapted to the present problem by adding the subroutines "FUNC," "SERIES," and "DONE." the n variables are required as input. Initial guesses of From the initial guesses, a polygon or "simplex" consisting of n+1 vertices is generated. values at each of the vertices are calculated and compared. Function The vertex having the highest function value is replaced with another point by reflection of that point through the centroid of the simplex . Three operations reflection, contraction, and expansion -- are used in the replacement. The coefficients ALPHA, BETA, and GAMMA give the factor by which the volume of the simplex reflection, contraction, or neighborhood of the minimum, is changed by the operations of expansion, the respectively. simplex contracts. In the The process continues until the condition ~f (Yi - y)2/n ~ 1 X 10-5 i =1 is net. and y The Yi's are the values of the function at the n+1 vertices is the average of the Yi ' s. On output, the program prints the current val ue of each of the variables, the value of the function being minimized, and the number of ZOS the current function evaluation. After 50 function evaluations, the above information is printed out at only at intervals of SO evaluations or when the stopping criterion is rret. When the stopping criterion is met, the total number of function evaluations required is printed as we 11 as the mi ni mum va 1ue of the func.t i on and the values of the variables at the function minimum. In the example listed, the following input parameters were used: N:4 H=O.S ALPHA=1 .0 BETA=O . S GAMMA=Z.O X(l,l)=A 1=Z . Z X 10 4 X(l,Z)=E 1=19900 X(l,3)=AZ=1.1 X 10 13 X(l,4)=E Z=44BOO. The values of H, ALPHA, BETA, and GAMMA are those found by Nelder and Mead to require the fewest function evaluations. The values of the four input ki netic parameters are those found by the differential rrethod (Arrheni us plat). A minimum function value of 0.0149 was found after 117 function evaluations. Final values of kinetic parameters at the minimum are: 206 A1=2.2 X 10 4 • E1=20800. A2=1. 7 X 10l3. E2=44800. The values of the kinetic parameters found at the minimum are not significantly changed from the input values, indicating that the values calcu lat ed by the Arrhenius method are quite good estimates. 207 Program listing 1. 2. C C 3. C PROGRAM ·FUHHIN" ADAPTED FEB, 19B3 •• C 5. C PROGRAM TO FIND THE MIHHtJH OF' It. FUNCTION. F. OF KANT VARIABLES USING TIiE SIMPLEX METHOD OF liELDER AND KtAD. 6. 7. C C FUHClIOI/ TO BE HINlKIlrD IS GIVDI IN SUBROUTINE "FUNC" s. 10. 11. 12. C C C C C 11<, 15. 16. 17. C C C C 1S. 19. c 20. 21 . 22. C C C Ii 23. C 21<. C 25. 26. 27. C C C H scale factor used to det.ermine the coordinates of the JrI+ 1 vertices of the simplu 1n Ji-dlmenslonal apace 28. 29. 30. C C C BETA 31. C GAMHA 32. C g. 13. 33. C c c 3". C 35. C 36. 37. C C 38. C 39. C .110. 41. C C FOR D£TAI~ VARIABLES: In ..1n pro,ram ••• ALPHA 1(1,J) IrrlY contlin1nl the 18 vllues of conversion frolll eiperilllental runll Irray contllnlnl the 18 cllcullted valuu of conversion It the 18 temperltures of array T C C C Zl c F 52. 53. "'. 55. C C C 56. 57. c C c J=1,II. IrrlY contllnlnll inltial lunses of Ylrllbles with respect to which the function ill to be III1nillliud I IiIIl. C C ex pansion coeffie:1ent, GAHMA>1.0 array containinl the 18 values of lIIull11UIII telllperlture re lched in the 18 linear_hutinl runs 115. 116. 50. 51. contraction coefficient, O.O<BtTA<1.0 T C C reflection coefficient, lLPHA>O.O In subroutine 'f'\JNe' •• • C 119. number of Vlrllbhs 'IIith respect. to which the function 111 to be 1II1nlm1%ed 43. c lHE METHOD, SEE THE FOLLOWING REFERENCE: NeIder, J. A•• nd R. Head, "A Simplel Method for Function MinimizatIon," Coroou ter Journ".1:308313( 1965). 42. .117. 118. or ICON arrlY (!Ontllninl values of function to be IIIin_ imized countinl variable 208 58. c 59. 60 . C C C C ". 62. 65. c c c 66. C 63. (;I. 67. 68. I,IRV,J ARC' ,ARGZ BB C JJ 70 . C C C S1 7'. 75 . 76 . 77. 78. 79 . 8D. 8'82. ... index variable telllporary variable 1n calculation of value of SERIES c c URG C SERIES c argument of p(x). passed frOIll subroutine 'FUNC' value of series approximation of pel) function C COMMON X( 111,10) ,F( 111) ,N.l CON READ( 5.1 OlN ,H, ALPHA ,BETA ,GAHHA 10 2D 83. 85 . 86. 87. 88. array containing the eight Bernoulli nullbers used 1n series approximation of pCx) c c 73. arguments of p(x) fun ctiQn , ElIRT or EURl In f1Jn etion subprogram 'SERIES' ••• 69. 71 . 72. index variables FORMAT( 15 ,1IF1 0 . 3) READ(5,20)(X(' .J ) ,J=l.N ) FORHAT( IIF1S .0) WRIT£(6 . 30) 30 FORMAT( lHl) ICON=D INDEX" 1 liP,.:"," 1 NYl",H.2 NY2=N+3 89. 90. 9'92. NY3::.N+1I 93. 00 lOa K::l,N X{J,K)::X(l,K) IF{ JH .EQ. K ) X(J ,K):X(J ,K)-' 1.H) CONTINUE CAJ..L FUNC",NP1) CAJ..I. ORDER DO 110 J:::l ,N X(HY1,J)::0.0 00 120 I:Z.NPl X( HYl,J):X( HYl,J).X( I .J)/N X( NYZ ,J)= X( JoN 1 ,J) - ( 1 .+ALPHA) -ALPHA- X( 1 ,J) CALL FUNC(HY2,NYZ) IF( F(NY2) .LT. F ( NP1) ) GO TO 500 00 130 IC:N.Z._1 IF( F(HY2) .I.T. F(lC) ) GO TO 1000 CONTINUE IF( F(HY2) .LT. F(11 ) CALL INSERT(HY2,D DO 140 J=l,N X( JoN3 ,J 1 :BETA -X( 1.J h{ 1.-BETA) - X( NYl ,J) CALL FUNC(NY3.NY3) IF ( F(NY3) .I.T. F( 1) ) GO TO 1500 00 150K:l,N DO 100 J:2,HPl JM:.: J-l 9'. 95 . 95 . lOD 97. 98. 99. 11000 100. 10L 102. 12D 103. lOll. 110 105. 106. 107. 108. 109. 110. 111. 112. 11 3 . 1111. 130 '"0 209 115. 00 150 J:l.H "6. 117. 118. 119. 120. 121. 122. 123 . 150 1500 160 X(K,J):.S.(X(K,J)+X(NP1,J» CAlL FlJNC(l,N) CAl.l. ORDER RIbS GO TO 3000 DO 160 IC=NP1,2._1 IF( F( NY3) .1.E. F{IC) ) GO TO 2000 CONTINUE 12!1. CALL INSERT( NY3 . 1) 125. 126. 127. 128. 129 . GO 10 2500 CAll IHSERT(NY3.IC) KIL;" GO TO 3000 CALL IHSERT(HYZ.ICl 2000 2500 1000 130. KIL=3 131. 1)2. GO TO 3000 00 170 J:l.N 500 170 133. nil. X( NY3 ,J ) :GAMMA · XOin , J h( 1 ._GAMMA) .X( NYl ,J ) 135. CAll FUNC(NYJ.NY3) If( F(KY) .1.1. F(NY2) ) GO TO 3500 136. CALL INSER1(HY2,NP1) 137. KIl.:2 138. GO TO 3000 139. 140. 1111, 142. 1/13. lilli, 3500 3000 145. 1116. 141. CAlL INSERT(1IY3.NP1) KIl.:l CALL ERR(KIl.,INDEX) If( INDEX .EO. 1) GO TO 4000 IF(INDEX.EQ.Z) CAlL DONE(NY3 .HY3 ) STOP END C C 1118. SUBROUTINE INSERT( NHY ,NLOW) 149. 150. 151 . 152. 153. 1511. 155. 156 . 157. 158. 159 . 160. 161. 162. 163 . COHMON X(14,10),F(14), N,I CON IF( HLOW .EQ. 1 ) GO TO 100 00 10 1:2,NlDW J:I_l F(J):F(l) 00 10 K= l,N X(J ,K) :X{l ,K) F(NLOW)=F{NHy) D020K=l,N X(NLOW,K):X(NHY,K) RETURN END 1611. 165. 166. 167. 168. 169. 170. 171. 10 100 20 C C SUBROUTINE ORDER COHJoKlN X(1I1 , 10),F (111) ,N,ICO N DHENSION UclO) NP1:H+l 00 10 J=2,NPl JK:J-l 00 20 K:J,NPl IF( F{JK) .G'T. F (K) ) GO TO 20 JK:K 210 20 172 • 10 183. 1811. 185. c c 187. 188. 189 . 190. 19 1. 192 . 193. 1911 . 195 . c "'. IN THIS SUBROUTINE , F (THE CONVERSION) IS CALOJLATED USI NG THE CURRENT VALUES OF TKE FOU R KINETI C PARAHETERS ; X( I.J) , J=1 ••••• 11 EXTE RNAl,. SERIES REAL T(16) . Y(181,ZY(18) CO HMON X{ 111,10) .F{1I1) ,N , ICON DATA T1560 • • 561 •• 571 .• 589 . • 593 . ,603 . , 611 • , 6211. ,626 •• 632. , 6110.,6112 • • 6117 •• 655 . ,661. . 610 .. 618. , 683.1 DATA YlO . 689 . 0 . 0 . 0 .23,7 . 5 77 . 9 .11111 . 17 . 1151 . 17.1151,26.292,26 .521 , I 311.673 ,116.1198 , 51.320 ,58. 898 , 68.082 ,88 . 175 ,87 . 026 . 96.9 .99 . 11261 R: 1.987 8: 0, 195 DO 10 I=INn ,lEND ICON",ICON.l SU l1 lEO . O 00 20 IRhl,18 ARG lE.X{ I , 2)1 ( R" 1{ IRV» ARG2,.-X{ I,ll) 1 ( RI T{ IRV) ) ZY(IRV) :Y ( IRV)/1OO . su Hl '" SU i'll . ( zy ( IRV) . ( 1. ElP{ . X{ 1,1 ) I X( 1 . 2) 1 SERIES( ARG1)1 (BI R) • X{ I . 3) 1 Xc I . 11) 1 SEftIES{AR(2) 1 (BI R»» 11 2 2 0 CONTINUE f( 1):SUHl 10 CONTINUE 00 30 J: INn , lEND If( lCON.LE .50) \lRITE( 6.100) ICON . (X( J ,K), K: l,N ) • F (J) If( ICON. EO. , 00 . OR.I CON . EO. 150 , OR. I CON • EO . 200 . OR . I CON . Gt. 250) \1'1111£( 6 . 1 00) ICON,(X( J ,K l , K=l,N),F ( J ) I 30 CONTINUE FOllHAT( • fUNe EVAL ' . I3 ,5X .'F { ' , II ( t 12.6, ' . ' ) ,' )o:',f'1 0 . 5) IIEl\JRN • 198. 199. ' 00. 201- '02 . 203 . ."'. 2 05 . 206. 207 . 208. • '09. 228 . SUBJlOUTINE FUNC(INIT.IE ND) c c c 197. 225 . 226. 227 . END c , 96. 210. 211. 212. 213. 2111 . 215. 216. 217. 218. 219. 2Z0 . 221. 222. 223. 2211 . DO 30 L: l . N lA (LhX( JH1 .L ) X( JH1,L):X( JX,L) X( JX . L) : :tA ( L) TO. f'( J 11 1) f(JH 1) =F (JX) f'(JK ) ,.FD RETURN 30 '80. 181. 182 . CONTINUE JH 1 ~J-l 173. 1711 . 175. 176. 177 • 178. 179. 10' c END c SUBROUTINE tRR ( I.K ) CO HKO N X( 1I1,1 0) ,f' { 111 ) , N,tCON NPh .... , IF ( K .to . 2 ) GO TO 2500 SU"'" O. SUI1hO 00 10 J K: 1,NPl 211 212 Sample Output fUII C [VAl. F~C [ 'OJ. r UNC [ VAl fllN C EV.u. FUN C IV ll.. FlINC EV ll.. r UNC £VAL. SIMPLD: rUHC [VAl. nINe [VAl 5 5 5 5 5 F( F( F( F( F( F( F( .220000.005. .199000.005. .106000.0111, ,1.118000.005 .)0: .330000.005 • .199000. 005 , ,1060oo.0HI, ... .118000.005 .) . .22 0000.005. .298500+005. .106000.01 ", ,tII800o.00S.h .220000.005. .199000. 005. .159000 . 0111 • ,11118000. 005, )· .220000.005. ,199000.005 , . 106000.01", .67 2000+005. h • " 0000.005. .2118750.005 • .132500.0111 • • 560000.0OS.h 7 .275000.005 . .2111137.005 . . , ,2625.0111 • ,1176000.005. )"' REFLECTED U D CONTRACTED • ,• F( F( F( • 165000..005 , .236312.005 . .2.11 7500. 005. .21 7656.005 • 13 . 2117500.005 . ,251196;.005. . 220000.005 • • 2118150.005, 13 .220000.005 . • 2118150.005, 13 F( .220000.005 • • 2118150.005 , 13 CONTRACTED .31078 .69250 .106110 .51669 • '11230 •• 92987 . 55933 ,125875.0111, .532000+005. ) • '.116021 • "5937.0111, ,1190000.005. ). ,109312.0111 , , &162000+005 ,)& . 132500.0111, .11118000.005. ). .106000.0111, .11118000.005 . ) • .106000.0111, . 560000.005, )& 1.791193 1,093111 ,011680 .09681 11.781113 r UNC EVAl .2 33750+005 , .2767311.005, .120906.0111. .3 11 3000+005,)& rlJ)i C £VAl 15 .223 11 37.005. .2557116.005, .109127.0111, .505750.005,). SIMP1.EX JlEFLECTED JJl D CONTJlACTED 8.35513 1I.6()11113 FUNC EVAl • 2303 12.005, .269738. 005. .117180.0111 • .397250.005. )& FlJ)i C £VAl. F( .225156. 005. .25921111.005, .111590.0111 , .117 8625.005 , )& SIMP1.EX REf1.ECTED JJl D CO NT RACTED 5 . 163118 3.03019 r UNC £VAl. .22859 11.005 • • 2662110.005 , . 1 15316.0111 . .11211375.005. )& FUNC £VAl. . 2277311.005 • • 26111191.005. • 11 11 385.0111, .1137937.005,) • SIMP1.EX REf1.ECl£D JJlD COJriTRACTED 1.669119 .269112 F( • 196367.005 , .275277.005 . .120130+011', .1128969. 005. ) • FlJNC tv Al. 2. F( .23 11 717.005. .260011 6.005. . 112017.0111, . 11537112.005,)· FUNC £VAl 21 SIMP1.EX REF1.ECTED JJlD CONTRACTED 1.16907 .311880 FUNC tvAl. 22 .209150.005 • • 270200+005 . . 1171126.0111. .1137227.005 . )& F( . 2155112. 005. .267661.005 , • 116073·0111, . 1111 1355.005.) • rUN C [VAl 23 SIMP1.EX REF1.ECTED JJlD CONTR ACTEO . 33718 .11208 r UNC EVAI.. .21 0037.005, . 267339.005. • 115902.0111. .115.117110.005 , ) • FLIN C £VAl 25 .223310.005 • • 265203+005 . • 11117611.0111. .11112138.005, ) • SIMP1.EX REf1.ECTED AN O CONTRACTED .39310 .081109 F( .226113·005. .26;:>9110.005 , . 113559·0111, • .11517' .... 005.)& FUNC tvAl.. 26 rUN C [VAl. Z7 F( .218 185.005. .2661181.005, .11 511115.0111. .111139115+005 . )& SIMP1.EX REF1.ECTED AIlD CONT IlA ClED .22189 .051113 F( .2207117.005. .216092.005 , .1283511.0111, .111130112.005,). FlJNC £VAL 2. F( . 220181·005. .277898.005 , .111589.0111, .11116760+005,)& rLlNc £VAl. 29 SII'lPLLX JtEF1.ECTtD AN D CONTRACTED .17550 .06059 FUM C [VtJ, 3. F( .2208111 .005. . 2801116.005, . 131'119·01.11. .11"2.1122.005. )& FUNC [VAl. 31 F( .22 02 10.005. .256667.005 • • 112287. 01". .11116605.005, )& SI)(f1.EX REF1.ECTEO JJl D COIl1RACTED . 12825 .051192 FUMC EVAI.. J2 F{ .215981.005 •• 259695+005, • 1211116.0111. .1150517+005,) • r UNC [VAL 33 .2211178.005. • 26)826.005. • 116360.01 •• • 111111233+005 , ) .. SI)(f1.EX REF1.ECTED AN D CONTRACTED .13196 . 011952 FUN C [VAL FUNC EVAl r UNC EVAl FUN C EVAl SIMP1.EX "" " "" "" " " "" '. .. " "" " 213 f UNC EVAl. FlIN e [VAL 3' F( .21 97 119+005 . f UNC EVAl. F lIN C tv A.l. 36 F( 37 F( . 220073+005 • 38 F ( • 222629. 005 . F( .219296. 005 . . 2399611. 005 . . 126707+01", ,11 111163 ' .005 . )'" F( .220077 . 005. .268 414+005 . .11 5368 . 01 11 , ,11116228.005,)= 35 SIHPLEX REFLECTED AND CO NTRACTED .2 19660.005 , . 2 67069· 005 . ,1275119·0111, . 111111598. 005 . h . 259267. 005 • • 1'6103·0111, .1:1-116103+005 . ) ,. SIMPLEX REFlECTED AND CONTRACTED FUNC £VAL FlINC tv Al. 39 .06099 . 0118115 .05998 .04627 .2536118. 005 • .1 24721.014 . ,.1111 8337. 005 . )" .263273+005 • . 1117 611 . 0UI • • 1111 50113+ 005 ,) ", .061011 . 011508 . 2182115. 005 . .256026. 005 , ,1211508. 0 111, .448'154. 005.)= . 061121 . 0111150 SIMPLEX REfLECTE D AN D CONTRACTED FUN e [VAl fUN e EVAl. "" F( F( . 220670. 005 • . 26 1816+005 , . 11 8)97+0 111 , .11115288.005, ): SIMPLEX REfl.ECTED Mi D CO NTRA CTED F( .219942+005. SIMPLEX REfLECTED SUCCESSfULLY .~1.I8 169. 005 , .12701].0111 , ._115989. 005 , ) '" . 01.11.195 F( .219990+005 , .2675112. 005 , .1 07138. 01 1.1. . _113212.005, )II: f UNC [ VAl '3 F( • 219997. 005 , .2534118.005 • . 126 160.0111 , .4116803+005 , ) ,. fUN C £VAl SIMPLEX REFLE CTED AN D CONTRACTED . 011903 .04111.15 F( .219880. 005 , .254116. 005 . .128564. 011.1 . .41.15458. 005. ): FUMC EVAl F( . 2200211. 005 , .257979.005 , .119218.0111 , .1.11159112.005,)'" fUNC EVAl SIMPLEX REFLECTED AN D CO NTRA CTED .05031 .0111123 F( . 221021.005, . 21.17 11 63. 005 , .1 27630.0 111, .411 6968. 005 . ),. fUNC £VAL F( .221883.005, . 239559.005 • . 132563· 011.1 • •1147931 . 005 , )'" FUN C EVAL SIMPLEX EXPANDED .0 4 359 . 011289 f UNC EVAl Fe .2213116.005. • 258262. 005. .121 155.011.1 • .11_6993+005. ): F( . 220293·005 , . 250692. 005 , . 1255£19.0111 , .1111621.10.005 . ): FUNC EVAL 50 SIMPLEX REFLECTED AND CONTRACTED .049111 . 04375 FUNC [VAl 100 . 01507 FUNC EVAl " " "" "" " F( . 216707. 005, .207371 . 005, .165779.014, .115760 1. 005 . ): STOPPING CRITERIA HAS BEEN MET 117 FUNCiION [VALUATIO NS WERE NEEDED 21686. 20816. . 16578.0111 11 5728 . 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