Catalytic hydroconversion of extraction residues from two Chinese lignites to arenes

Abstract

A solid superacid TFMSA/MPZCA was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) into mesoporous zirconia-coated attapulgite (MPZCA). Using TFMSA/MPZCA, the catalytic hydrocracking of coal-related model compounds (CRMCs) oxybis(methylene)dibenzene (OBMDB), benzyloxybenzene (BOB), and di(1-naphthyl)methane (DNM) and the catalytic hydroconversion (CHC) of extraction residues (ERs, isometric carbon disulfide/acetone-insoluble portion) from Huozhou lignite (HL) and Shaerhu lignite (SL) in cyclohexane without H2 were investigated. According to the model reactions, H+ released from TFMSA in TFMSA/MPZCA plays a crucial role in cleaving the > Calk-O- and > Car-C < bridged linkages (BLs) in the CRMCs, and the BLs of > Calk-O- in OBMDB and BOB can be completely cleaved at 170 °C and 190 °C for 3 h, respectively, while the BL of > Car-C < in DNM was not completely cleaved even at 320 °C. At 300 °C, the yields of soluble portions (SPs) from the CHC of HL- and SL-derived ERs significantly increase compared with the non-catalytic hydroconversion of both ERs. Arenes are predominantly abundant in the SPs from the CHC of both ERs and the most abundant compound in the SPs is mesitylene.