Investigating the impact of temperature on oil shale conversion via supercritical methanolysis: Experimentation, characterization and mechanism insight

In this study, supercritical methanolysis experiments were conducted for Chinese Beipiao (BP) and Jordanian El-Lajjun (EL) oil shales at various temperatures. The methanol-soluble portion (SP), insoluble residue (ISR), and gas were collected and analyzed, revealing the reaction mechanisms and temperature effects in oil shale supercritical methanolysis. The obtained results demonstrated that supercritical methanolysis of oil shale could achieve a mild conversion (<400 °C). The presence of methanol significantly enhanced the SP yield, exceeding the shale oil yield from oil shale obtained from pyrolysis. Maximum SP yields of 5.33 % and 14.43 % for BP oil shale and EL oil shale, respectively, at 370 °C. The results showed that the primary components of the SPs were n-alkanes and fatty acid methyl esters (FAME). Additionally, a comprehensive characterization of the products obtained at various temperatures during supercritical methanolysis identified 11 possible chemical reactions. These results elucidated how temperature influences the molecular composition and structure of methanolysis products, revealed the reaction mechanism underlying oil shale's supercritical methanolysis, and verified the feasibility of producing liquid fuels through this process.