Insight into molecular compositions of soluble species from sequential thermal dissolution of Liuhuanggou bituminous coal and its extraction residue

Liuhuanggou bituminous coal (LBC) and its extraction residue (ER) were thermally dissolved sequentially in cyclohexane, toluene, and ethanol at 300 °C to obtain soluble portions (SPs) 1–3 (SP1-SP3) from the thermal dissolution (TD) In the total yield (TY) of 10.4% and SPs I-III (SPI-SPIII) from the TD in the TY of 4.9%, respectively. The SPs were analyzed by multiple analytical tools, including gas chromatograph/mass spectrometer (GC/MS), quadrupole exactive orbitrap mass spectrometer (QEOTMS), and Fourier transform infrared spectrometer. The analysis with GC/MS shows that normal alkanes are the most abundant in SPI, while arenes are predominant in SP1, SP2, and SPII. According to the analysis with QEOTMS, abundant heteroatom-containing organic species were concentrated into SP3 and SPIII with molecular masses of 150–750 u. The relative contents of N1 and N1O1 species are predominantly high in SPIII and SP3, respectively.