Catalytic hydroconversion of the light residue from Yinggemajianfeng lignite over a solid superacid

Abstract

TFMSA/ATA was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) onto the acid-treated attapulgite (ATA). Yinggemajianfeng lignite was extracted ultrasonically with a mixed solvent obtain the extract and extraction residue (ER), and then ER was separated by density difference to obtain the light residue (LR). The non-catalytic hydroconversion (NCHC) and TFMSA/ATA-catalyzed hydroconversion of LR were investigated in cyclohexane at 160 °C under 4 MPa of initial hydrogen pressure for 12 h. The soluble portions from NCHC (SPNCHC) and catalytic hydroconversion (SPCHC) were analyzed with a Fourier transform infrared spectrometer and gas chromatograph/mass spectrometer. As a result, the yield of SPCHC (60.0%) is significantly higher than that of SPNCHC (1.8%), suggesting that the thermal dissolution of LR at 160 °C is negligible and TFMSA/ATA significantly catalyzed the hydrocracking of LR to release SPCHC. Oxygen-containing organic compounds, especially 4-methylpent-3-en-2-one and 4-hydroxy-4-methylpentan-2-one, are predominant produced from the CHC of LR, suggesting that the cleavage of > Cα-Oβ- and > Cβ-Oα- bonds in LR significantly proceeded during the CHC of LR over TFMSA/ATA. Such a mechanism was proved by the CHC of oxybis(methylene)dibenzene.