Catalytic Hydroconversion of Ethanol-Soluble Portion from the Ethanolysis of Hecaogou Subbituminous Coal Extraction Residue to Clean Liquid Fuel over a Zeolite Y/ZSM-5 Composite Zeolite-Supported Nickel Catalyst

A novel and highly active zeolite Y/ZSM-5 composite zeolite (CZ)-supported nickel catalyst (Ni/CZ with 10% of Ni loading) was prepared by modified deposition–precipitation to uniformly disperse Ni nanoparticles (NNPs) onto CZ. Hecaogou subbituminous coal was exhaustively extracted with isometric carbon disulfide/acetone mixed solvent to afford the extractable portion and inextractable portion (IEP). Ethanol-soluble portion (ESP) was obtained by ethanolyzing the IEP at 300 °C and subjected to catalytic hydroconversion (CHC) over Ni10%/CZ at 160 °C to afford catalytically hydroconverted ESP (CHCESP). Both ESP and CHCESP were analyzed with a Fourier transform infrared spectrometer, gas chromatograph/mass spectrometer (GC/MS), and quadrupole exactive orbitrap mass spectrometer. The results show that the relative contents (RCs) of both chain alkanes and hydroarenes in CHCESP are significantly higher than those in ESP and cyclanes and alkenes were only detected in CHCESP, while the RCs of both arenes and oxygen-containing organic compounds in CHCESP are much lower than those in ESP and nitrogen- and/or sulfur-containing organic compounds were only detected in ESP with GC/MS. According to the CHC of oxybis(methylene)dibenzene (OBMDB), Ni10%/CZ can effectively activate H2to biatomic active hydrogen (H···H) and the resulting H···H was heterolytically split into an immobile H–attached on Ni/CZ and a mobile H+. H+transfers to an oxygen atom (OA) in OBMDB and cleaves the C–O bridged bond to produce phenylmethanol (PM) and benzylium, followed by H–abstraction from the Ni/CZ surface by benzylium to form toluene. H+transfer to the OA in PM also leads to the cleavage of the C–O bond in PM to produce H2O and benzylium, which abstracts H–from the Ni/CZ surface to yield toluene. H···H transfer to the benzene ring in toluene generates methylcyclohexane. Therefore, Ni10%/CZ catalyzes both H+and H···H transfer. In addition, it proved to be stable for the CHC of OBMDB after 3 cycles.