Comparison of pyrolysis characteristics of two Chinese oil shales based on the migration and conversion of organic carbon

In this study, the Huadian oil shale (HD-R) and Balikun oil shale (BLK-R) were pyrolyzed in a fixed-bed pyrolyzer at 360–530 °C. Based on the migration and conversion of organic carbon, their pyrolysis characteristics were investigated and compared. The aliphaticity of Huadian kerogen (HD-K) and Balikun kerogen (BLK-K) are 80.53% and 52.83%, respectively. The HD-K contains more CO, which will render the depolymerization and decomposition of kerogen to occur at low temperatures to produce volatile matters. Thus, the cumulative conversion of the Huadian shale oil is greater than the Balikun shale oil at 390–435 °C. The aliphatic carbons of the BLK-K are mainly present as short methylene chains attached to aromatic rings. They will leave the kerogen matrix with the breakage of relatively weaker CC bonds at β-sites from aromatic rings at medium temperatures. By contrast, aliphatic carbons of the HD-K are dominated by long aliphatic chains. High temperature is necessary to break other stronger CC to form shale oil and gaseous species, which appears to make the oil accumulation conversion of BLK-R exceed that of HD-R at 450–510 °C. Keywords: Oil shale, Pyrolysis, Kerogen, Organic carbon, Thermal bitumen, Shale oi