Kerogens decomposition rate

Kerogen Decomposition. The thermal decomposition of oil shale, ie, pyrolysis or retorting, yields Hquid, gaseous, and soHd products. The amounts of oil, gas, and coke which ultimately are formed depend on the heating rate of the oil shale and the temperature—time history of the Hberated oil. There is Htde effect of shale richness on these relative product yields under fixed pyrolysis conditions, as is shown in Table 5 (10). 

The rate of kerogen decomposition into oil and gaseous products can be an important factor in process design, as can the relative amount of oil and gas produced. Nonisothermal gravimetric analysis was used to compare the relative thermal decomposition rates of the kerogens in the shales under investigation. Details of the pyrolysis studies are presented in the following sections. 

First-order rate expressions are proposed in Table I for the three principal steps light hydrocarbon production (equals kerogen decomposition), primary heavy oil production, and coking. 

Carbon Monoxide. All shale samples showed a significant peak in the Co evolution rates in the temperature range over which oil evolution occurs. At these relatively low temperatures, it is unlikely that the reaction between CO2 and residual char could be a significant source of carbon monoxide (2), and it appears that for these shales and in contrast to the Green River shale (2), the decomposition of the kerogen results in the formation of CO. In the case of the Stuart shale, the processes leading to the formation of the CO in the low temperature range are characterised by a mean activation of n/ 174 kJ mo 1-1 and a distribution of 11 kJ mol-1 (Table 6). 

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