Coupling of methoxy group with organic matter during methanolysis of heavy hydrocarbon using oil shale as an example

Abstract

Alcoholysis has been extensively studied for the conversion of heavy hydrocarbons such as coal and biomass, but the roles of alcohols have not been well elucidated. This work aims to investigate the roles of methanol during methanolysis of heavy hydrocarbon with oil shale as an example. It is found that the oil yield of methanolysis is always higher than that of pyrolysis regardless of the reaction temperature but the effect of methanol on the solid product yield is temperature-dependent. At temperatures lower than 290 °C, methanol promotes the oil shale conversion and the solid product yield of methanolysis is lower than that of pyrolysis, which is mainly attributed to the strong supercritical extraction capability of methanol on the oil shale’s pyrolysis products as well as the promoting effect of methanol on reactions of ether oxygen and carboxyl/carbonyl bonds. At temperatures higher than 320 °C, coupling of methoxy moiety in methanol with the organic matter of oil shale and its pyrolysis products as well as the methanol aromatization lead to the formation of oil components such as aromatics, phenols and high boiling point compounds, which result in the increased oil yield. The complex methanol reactions also make methanol become parts of the solid product, leading to a higher solid yield in the methanolysis in comparison with the pyrolysis.