Insight into the structural features of organic species in Fushun oil shale via thermal dissolution

Abstract

Abstract Fushun oil shale (FOS) was subjected to thermal dissolution (TD) under different conditions. The results show that the optimal solvent, temperature, time, and ratio of solvent to FOS are ethanol, 300 °C, 2 h, and 5 ml·g− 1, respectively and the corresponding yield of the soluble portion (SP) is 32.2% (daf), which is much higher than the oil content of FOS (ca. 6%), suggesting that TD in ethanol is an excellent way to extract organics from FOS. According to 3 direct analyses, aliphatic moieties in FOS are the most abundant followed by C O-containing moieties and each cluster in FOS has 3 conjugated aromatic rings on average with fewer substituents. According to the analysis with a gas chromatograph/mass spectrometer, alkanes are predominant in all the SPs. A number of alkenes were identified in the SPs from the TD, while none of the alkenes were detected in acetone-SP obtained at room temperature, implying that the TD can destroy the π-π and intertwining interactions between alkenes and macromolecular structures in FOS. Moreover, a small amount of alkyl-substituted phenols and alkoxy-substituted phenols were detected in ethanol-SP from the TD, which could be the products from ethanolyzing the macromolecular moiety of FOS.