Fluidized-bed pyrolysis of oil shale: Oil yield, composition and kinetics

A quartz isothermal fluidized-bed reactor has been used to measure kinetics and oil properties relevant to surface processing of oil shale. The rate of oil formation has been described with two sequential firstorder rate equations characterized by two rate constants. These rate constants together with an expression for the appropriate weighting coefficients describe approximately 97 percent of the total oil produced. A description is given of the results of different attempts to mathematically describe the data in a manner suitable for modeling applications. Preliminary results are also presented for species-selective kinetics of methane, ethene, ethane and hydrogen, where the latter is clearly distinguished as the product of a distinct intermediate. Oil yields from Western oil shale are approximately 100 percent Fischer assay. Oil composition is as expected based on previous work and the higher heating rates (temperatures) inherent in fluidized-bed pyrolysis. Neither the oil yield, composition nor the kinetics varied with particle size between 0.2 and 2.0 mm within experimental error. The qualitatively expected change in oil composition due to cracking was observed over the temperature range studied (460-540°C). Eastern shale exhibited significantly faster kinetics and higher oil yields than did Western shale.