Characterization of soluble portions from thermal dissolution of Zhaotong lignite in cyclohexane and methanol

Abstract

Thermal dissolution of Zhaotong lignite in cyclohexane and methanol was conducted at 300°C for 2h. The yields of the resulting cyclohexane- and methanol-soluble portions (CHSP and MSP) are 10.1% and 24.3%, respectively. CHSP and MSP were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS). According to analysis with GC/MS, the compounds detected in CHSP and MSP can be classified into alkanes, alkenes, arenes, arenols, anisols, ketones, esters, nitrogen-containing compounds, and sulfur-containing compounds. The most abundant group components in CHSP and MSP are arenols and arenes, respectively. The analysis with FTICRMS shows that On (n=1–6) class species with double bond equivalent (DBE) values of 1–15 are the main acidic compounds in both CHSP and MSP, and the predominant class species in CHSP and MSP are O2 and O3 class species, respectively. Arenepolyols and aromatic carboxylic acids with 1–3 rings account for most of the On class species based on DBE distributions. In addition, fatty acids are also present in CHSP and MSP. Combination of GC/MS and FTICRMS can provide detailed composition information on coal-derived liquids at the molecular level.