Study on the structure, pyrolysis kinetics, gas release, reaction mechanism, and pathways of Fushun oil shale and kerogen in China

Oil shale is of increasing interest as it is considered as an important alternative to traditional energy sources due to its abundant reserves. In this study, the pyrolysis mechanism of oil shale and kerogen was investigated by structural characterization and pyrolysis experiments. The experiments on the structural properties of the base showed that the minerals of the Fushun oil shale were the main components that influenced the pyrolysis of kerogen. Small differences in activation energy between the two were obtained by thermogravimetry, and the optimum heating rates were different. The gas-phase FTIR spectroscopy results showed that the main volatiles during pyrolysis were C2+ aliphatic hydrocarbons, CO2, CO, CH4, C2H4, and CO and CO bonded substances. The Py-GC/MS results showed that the species and yields of the kerogen and oil shale pyrolysis products from molecular level. Moreover, the reaction pathways for both the pyrolysis mechanism were predicted, which included the aliphatic chain breakage reaction, dehydrogenation to form olefin, and aromatization reaction. Based on these experimental results, this study provides a reliable theoretical basis for the future utilization of Fushun oil shale. •The mineral, elemental percentages and functional groups of Fushun oil shale and kerogen were summarized.•The connection and difference between them were revealed base on the results of kinetic analysis.•The release processes of CH4, CO2, H2O and C2+ aliphatic hydrocarbon products were studied in detail.•The process of breaking of weak bonds and aromatization reaction was analyzed from molecular perspective.