Sequential extraction and characterization of liquefaction residue from Shenmu-Fugu subbituminous coal

Liquefaction residue from Shenmu-Fugu subbituminous coal (LR_SFSBC) was fractionated into extracts 1-6 (E₁-E₆) and inextractable portion (IEP) by sequential extraction with petroleum ether, cyclohexane, methanol, acetone, carbon disulfide (CDS), and isometric CDS and acetone mixture (ICDSAM) followed by analyses with Fourier transform infrared (FTIR) spectrometer, gas chromatography/mass spectrometer (GC/MS) and atmospheric solid analysis probe/time of flight mass spectrometer (ASAP/TOF-MS). In total, 69.06% of LR_SFSBC were extracted by the sequential extraction. Large amounts of multi-substituted alkylarenes and hydroarenes were identified in LR_SFSBC according to GC/MS and FTIR analyses. A series of nitrogen heterocyclic aromatics and arylamines in LR_SFSBC were enriched in E₃. In total 61 compounds were detected with GC/MS, including 48 arenes with a total relative content of 98.72%, while 478 organooxygens, organonitrogens, organosulfurs, and organochlorines were detected with ASAP/TOF-MS. The double bond equivalent, carbon number, and molecular mass distribution of the compounds range from 0 to 13, 6 to 23, and 230 to 511 Da, respectively, by ASAP/TOF-MS analysis. E₁ with the yield of 33.47% could be converted to light oil by catalytic hydroconversion due to its high H/C ratio and low sulfur content, while E₅ could be a promising precursor for preparing carbon materials because of its high carbon content and C/H ratio.