Liquefaction of thermal extracts from co-thermal dissolution of a sub-bituminous coal with lignin and reusability of Ni-Mo-S/Al₂O₃ catalyst

Four thermal dissolution soluble fractions (TDSFs) with different thermal dissolution soluble yields (TDSYs) obtained from thermal and co-thermal dissolutions (CTDs) of a Chinese sub-bituminous Shenfu (SF) coal and lignin were characterized by elemental analysis, FT-IR and synchronous fluorescence spectrum measurements. The hydro-liquefaction properties of the four TDSFs and SF raw coal with and without catalyst were compared and the recycled use property of the catalyst in hydro-liquefaction of the TDSF from CTD of SF coal and lignin was further probed. The results suggests that the TDSF from the thermal dissolution (TD) of SF coal contained much more amount of aromatic components and polyaromatic hydrocarbons (PAHs) with 4 and more rings than those from the CTD of SF coal and lignin at the same temperature. TDSFs gave much higher liquefaction conversions and oil yields than SF raw coal in hydro-liquefaction with or without catalyst. Almost all TDSF was converted with much high yield of oil and the TDSF from CTD of SF coal and lignin gave higher yield of oil than that from the TD of SF coal in hydro-liquefaction with Ni-Mo-S/Al₂O₃ catalyst which demonstrated a good reusability in the hydro-liquefaction of TDSF from the CTD of SF coal and lignin. Carbon deposition was hardly observed in the 4 times recycle used catalyst.