High-pressure pyrolysis of Green River oil shale

Oil yields, compositions and rates of evolution are reported for heating rates from 1 to 100/sup 0/C/h and pressures of 1.5 and 27 atm. Pyrolysis occurred in an autogenous atmosphere and volatile products were allowed to escape the pyrolysis region continuously. Higher pressures and lower heating rates during pyrolysis cause a decrease in oil yield, although the effects are not additive. The lowest oil yield was approximately 72 wt% or 79 vol% of Fischer assay. Lower oil yield is generally accompanied by lower boiling point distribution, nitrogen content and density and higher H/C ratios. Oils produced at high pressure and slow heating rates are a clear amber color instead of the usual opaque brown. The effect of pyrolysis conditions on biological markers and other diagnostic hydrocarbons is also discussed. Existing kinetic expressions for oil evolution slightly overestimate the shift in the oil evolution rate vs. temperature with a decrease in heating rate. Finally, the rate of oil evolution is retarded by pressure, a factor not taken into account by current kinetic expressions.