Compositional And Structural Features Of Shenmu-fugu Coal Liquefaction Residue And Oxidation Using H₂O₂/acetic Anhydride

Coal liquefaction residue(CLR) is an important heavy organic carbon resource. In this work, solvent extraction, combined to FTIR, XPS, NMR, TG, GC/MS, DARTIS/ITMS, ASAPIS/TOFMS, ESI Obitrap MS and ESI FT-ICR MS, were used for characterizing the compositional and structural features of CLR from Shenmu-Fugu subbituminous coal. Optimized conditions were raised for oxidization of CLR using H2O2/ acetic anhydride. Several condensed arenes with high added value were enriched from petroleum ether extractable portion(PEEP) of CLR. Structural portions in PEEP were investigated by ruthenium-ion catalyzed oxidation and GC/MS analysis.Heteroatoms in CLR are mainly present as pyridine, amino, pyrrole, quaternary nitrogen, C-O, COO-, C=O, sulphone, sulfoxide, Aromatic sulfur, aliphatic sulfur, pyrite, and sulfate. CLR is rich in substituted and non-substituted aromatic sturctures, the typical average structural units are disubstituted naphthalene nucleus and trisubstituted anthracene/phenanthrene nucleus, besides some oxygen- and nitrogen- containg heterocycles. The p-p interaction, hydrogen bonds, and Van der Waals’ force were formed between condensed aromatic rings, alkyl, oxygencontaining, and nitrogen-containing groups, froming the assoctiated features in CLR. A typical “capsule structure” was proposed in this work based on the assoctiated features of CLR and solvent extraction behavior. Sequential extraction of CLR was investigated using “petroleum ether→methanol→carbon disulfide”. Isometric acetone and carbon disulfide mixture is suggested for preparation of “HyperCLR” by solvent extraction.Optimized conditions for oxidation of CLR1 using H2O2/acetic anhydride were: H2O2/acetic anhydride/CLR1 = 40 mL/25 mL/1 g, reaction temperature 65 oC, reaction time 36 h. Benzene polycarboxylic acids are predominant in the oxidation mixture with a relative content of 75%. Oxalic acid, malonic acid, succinic acid, and 1,2,3-tricarballylic acid were also identified in both of the oxidation mixture and organic phase from ruthenium-ion catalyzed oxidation of PEEP, indicating carbon bridge bonds in the CLR1.