Reaction mechanism and kinetics of pressurized pyrolysis of Chinese oil shale in the presence of water

A study of reaction mechanisms and chemical kinetics of pressurized pyrolysis of Chinese Liushuhe oil shale in the presence of water were conducted using an autoclave for simulating and modeling in-situ underground thermal degradation. It was found that the oil shale was first pyrolyzed to form pyrobitumen, shale oil, shale gas and residue, then the pyrobitumen was further pyrolyzed to form more shale oil, shale gas, and residue. It means that there are two consecutive and parallel reactions. With increasing temperature, the pyrobitumen yield, as intermediate, first reached a maximum, then decreased to approximately zero. The kinetics results show that both these reactions are first order. The activation energy of pyrobitumen formation from oil shale is lower than that of shale oil formation from pyrobitumen.