Effects of hydrogen and FeNi–S/γ-Al2O3 on the hydroconversion of extraction residue from Geting bituminous coal in cyclohexane

•Ultrasonic extraction is a necessary pretreatment prior to catalytic hydroconversion (CHC).•FeNi–S/γ-Al2O3 obviously increased the yields of soluble portion in E1 and E3 from ERGBC.•CHC over FeNi–S/γ-Al2O3 markedly increased the yields of 1–2 ring(s) arenes.•The resulting H and the stabilizing effect of H2 could play crucial roles in releasing methylarenes.

Extraction residue from Geting bituminous coal (ERGBC) via ultrasonic extraction with isometric carbon disulfide/acetone binary solvent was subjected to thermal dissolution (TD), thermal dissolution under pressurized nitrogen (TDN), non-catalytic hydroconversion (NCHC), and catalytic hydroconversion (CHC) in cyclohexane at 300 °C for 3 h. The catalyst was prepared by thermally decomposing Fe(CO)5 and Ni(CO)4 onto γ-Al2O3. The reaction mixtures from TD, TDN, NCHC, and CHC were sequentially extracted with petroleum ether, carbon disulfide, methanol, acetone, and isometric acetone/carbon disulfide binary solvent to afford extracts 1–5 (E1–E5). Detailed characterizations of the extracts were performed with a gas chromatography/mass spectrometer (GC/MS) and Fourier transform infrared spectrometer. The results show that the yields of E1 and E3 from CHC are appreciably higher than those from others, suggesting the great influence of CHC on the breakage of -CH2- and -O- linkages connected to condensed aromatic rings. According to analysis with GC/MS, alkanes and arenes are the most abundant species in each E1, in which most of the arenes are methylarenes. Arenols and phthalates are the predominant oxygen-containing organic compounds. Arenes with 1 or 2 ring(s) markedly increase by using H2, especially in the presence of the catalyst. The H. catalytically generated over FeNi–S/γ-Al2O3 and the stabilizing effect of H2 on the generated radicals could play crucial roles in cleaving bridged linkages connected to condensed aromatic rings and thereby enhance the yields of alkylarenes through NCHC and CHC. Related mechanisms for the formation of some species derived from NCHC and CHC of ERGBC are discussed.