Effect of bitumen-derived coke on deactivation of hydrodemetallation catalyst (Abstract)

A large-pore hydrodemetallation catalyst was coked with a solution of anthracene or bitumen in mineral oil in an Autoclave batch reactor to obtain coke levels up to 12%. After Soxhlet extraction and resulfiding, physical properties of the coked catalysts were determined, as well as their catalytic activities for hydrogenation (HYO), hydrodenitrogenation (HON) and C-N hydrogenolysis (CNH) using a mixture of naphthalene and indole in nheptane. It was found that the coke produced via bitumen appeared to be porous, whereas that from anthracene was nonporous. Catalytic activities of the coked catalysts decreased with increasing coke content, with HON or CNH activity being more deactivated than HYO activity. The same catalyst was aged in a laboratory flow reactor for a short time with a bitumen feed and the maltene fraction of the bitumen feed in nheptane solvent. A catalytic activity test was performed in-situ after the aging run. Another activity test was performed on the same catalyst after the catalyst was removed and Soxhlet extracted and resulfided. Two types of carbonaceous deposits were identified on catalysts following the flow aging runs: (1) Coke A catalysts - these consisted of deposits obtained directly after the aging run and activity test. The deposits contained relatively large amounts of condensed polymers and seemed to be related to the flash properties of the feed. Significant losses in catalyst surface area and pore volume were caused by this coke. Catalytic activities were best related to f residual, unblocked surface area and poisoned sites. Hydrogenation sites were appreciably more poisoned than CNH sites; and (2) Coke C catalysts - these contained deposits remaining after further Soxhlet extraction of Coke A catalysts. These deposits were typical of normal coke and tended to reach a limiting value with time. These aged catalysts contained less coke than Coke A catalysts and did not exhibit any loss in surface area and pore volume. Activity tests on these catalysts showed that the results were similar to those of the Autoclave-coked catalysts.

EFFECT OF BITUMEN-DERIVED COKE ON DEACTIVATION OF A HYDRODEMETALLATION CATALYST by Kuang-Shing Chu A dissertation submitted to the faculty of The University of Utah in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemical and Fuels Engineering The University of Utah June 1995 Copyright © Kuang-Shing Chu 1995 All Rights Reserved ABSTRACT A large-pore hydrodemetallation catalyst was coked with a solution of anthracene or bitumen in mineral oil in an Autoclave batch reactor to obtain coke levels up to 12%. After Soxhlet extraction and resulfiding, physical properties of the coked catalysts were determined, as well as their catalytic activities for hydrogenation (HYO), hydrodenitrogenation (HON) and C-N hydrogenolysis (CNH) using a mixture of naphthalene and indole in n­heptane. It was found that the coke produced via bitumen appeared to be porous, whereas that from anthracene was nonporous. Catalytic activities of the coked catalysts decreased with increasing coke content, with HON or CNH activity being more deactivated than HYO activity. The same catalyst was aged in a laboratory flow reactor for a short time with a bitumen feed and the maltene fraction of the bitumen feed in n­heptane solvent. A catalytic activity test was performed in-situ after the aging run. Another activity test was performed on the same catalyst after the catalyst was removed and Soxhlet extracted and resulfided. Two types of carbonaceous deposits were identified on catalysts following the flow aging runs: (1) Coke A catalysts - these consisted of deposits obtained directly after the aging run and activity test. The deposits contained relatively large amounts of condensed polymers and seemed to be related to the flash properties of the feed. Significant losses in catalyst surface area and pore volume were caused by this coke. Catalytic activities were best related to f residual, unblocked surface area and poisoned sites. Hydrogenation sites were appreciably more poisoned than CNH sites; and (2) Coke C catalysts - these contained deposits remaining after further Soxhlet extraction of Coke A catalysts. These deposits were typical of normal coke and tended to reach a limiting value with time. These aged catalysts contained less coke than Coke A catalysts and did not exhibit any loss in surface area and pore volume. Activity tests on these catalysts showed that the results were similar to those of the Autoclave-coked catalysts. v r TABLE OF CONTENTS ABSTRACT ................................................................................................................. iv LIST OF TABLES ....................................................................................................... ix LIST OF FIGURES .................................................................................................... xii LIST OF SYMBOLS ............................................................................................... xvii ACKNOWLEDGMENTS ......................................................................................... xxi CHAPTER 1. INTRODUCTION ....................................................................................... 1 2. BACKGROUND ......................................................................................... 5 2.1 Properties of Heavy Residue and Bitumen ................................. 5 2.2 Hydroprocessing Technology for Heavy Residue .................. 11 2.3 Chemistry and Reaction Mechanisms of Hydro processing ...................................................................... 1 8 2.4 Hydroprocessing Catalysts ......................................................... 29 2.5 Catalyst Deactivation ................................................................... 35 3. EXPERIMENTAL .................................................................................... 45 3.1 Catalyst. .......................................................................................... 45 3.2 Catalyst Coking in the Autoclave ............................................... 45 3.3 BET Surface Area and Nitrogen Pore Volume ....................... 56 3.4 Catalytic Activity Tests for Autoclave-Coked Catalysts .......... 56 3.5 Coke Extraction Experiments for Autoclave-Coked Catalysts ........................................................ 66 3.6 Flow Reactor Aging Runs ............................................................ 68 3. 7 Flash Calculations ........................................................................ 72 4. RESULTS ............................................................................................... 75 4.1 Fresh Sulfided Catalyst.. ............................................................. 75 4.2 Autoclave-Coked Catalysts ........................................................ 94 4.3 Properties of Extracted Coke from Autoclave-Coked Catalysts ...................................................... 1 28 4.4 Flow Reactor-Aged Catalysts ................................................... 133 5. DISCUSSION ...................................................................................... 158 5.1 Autoclave-Coked Catalysts ...................................................... 1 58 5.2 Flow Reactor-Coked Catalysts ................................................. 173 6. CONCLUSIONS .................................................................................. 183 6.1 Autoclave-Coked Catalysts ...................................................... 1 83 6.2 Flow Reactor-Coked Catalysts ................................................. 183 APPENDICES A. Mo AND Ni MASS BALANCE FOR FRESH AND BITUMEN +NICKEL TETRAPHENYLPORPHYRIN-COKED HOM CATALYSTS .............................................................................. 185 B. CALCULATIONS FOR NAPHTHALENE TETRALIN EQUILIBRIUM ....................................................................................... 197 C. EQUILIBRIUM CALCULATIONS FOR ETHYLBENZENE HYDROGENATION ............................................ 202 D. CORRECTION OF NAPHTHALENE REACTION RATE CONSTANT FOR EQUILIBRIUM ........................................... 214 E. EQUATIONS FOR RATE CONSTANTS IN THE INDOLE NETWORK ............................................................................ 219 F. CALCULATION OF EFFECTIVENESS FACTOR FOR MODEL COMPOUND REACTION ................................................... 222 G. CALCULATION OF SURFACE AREA, PORE VOLUME, AND PORE SIZE DISTRIBUTION .................................................... 232 H. EQUATIONS FOR EXPECTED PORE VOLUME AND SURFACE AREA ................................................................................. 244 vii ' I. CONVERSIONS AND PRODUCT MOLE YIELDS AT VARIOUS TEMPERATURES FOR AUTOCLAVE-COKED CATALYSTS ............................................... 247 J. RATE CONSTANTS OF INDOLE AND NAPHTHALENE NETWORKS AT VARIOUS TEMPERATURES FOR AUTOCLAVE-COKED CATALYSTS ...................................... 262 K. CALCULATION OF IN-SITU RATE CONSTANTS AND RELATIVE ACTIVITIES FOR FLOW REACTOR-AGED CATALYSTS ....................................................... 277 REFERENCES ....................................................................................................... 280 viii