Catalytic hydroconversion of Shaerhu subbituminous coal over an Ni-based MOF-derived carbon matrix superacid catalyst

A magnetic solid acid, TFMSA/CNOFW, was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) into a calcined nickel-organic framework (CNOFW) at room temperature. The extraction residue (ER) of Shaerhu subbituminous coal (SSBC) obtained by ultrasonic extraction with an isometric carbon disulfide/acetone mixed solvent was subjected to non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) over the TFMSA/CNOFW in <i>n</i>-hexane at 300 °C for 4 h. The soluble portions from NCHC (SP_NCHC) and CHC (SP_CHC) were analyzed using a gas chromatograph/mass spectrometer. Results suggest that, compared with SP_NCHC, the introduction of the TFMSA/CNOFW dramatically improved the yield of SP_CHC (from 14.1% to 35.8%). Furthermore, arenes and oxygen-containing compounds were predominant in SP_CHC without cyclanes, indicating that the TFMSA/CNOFW efficiently promoted the cleavage of the [double bond splayed left]CH-O- bridge bonds in SSBC without hydrogenation of aromatic rings. The TFMSA/CNOFW can facilitate the transfer of mobile H⁺ from heterolytic H₂ to the oxygen atom on the [double bond splayed left]CH-O- bridged bonds in SSBC or the substituents of the aromatic rings connected by bridge chains, leading to breakage of the bridged bonds. Such a mechanism was demonstrated by the CHC of 2-(benzyloxy)naphthalene.