Catalytic hydroconversion of lignite-related model compounds over difunctional Ni-Mg2Si/γ-Al2O3

•Difunctional Ni-Mg2Si/γ-Al2O3 was developed for CHC of lignite-related model compounds.•Oxydibenzene was completely converted to cyclohexane under optimal reaction conditions.•The reaction mechanism for CHC of oxydibenzene over Ni-Mg2Si/γ-Al2O3 was proposed.•CHC over Ni-Mg2Si/γ-Al2O3 includes hydrocracking, dehydroxylation, and hydrogenation.

Catalysts Ni/γ-Al2O3, Mg2Si/γ-Al2O3, and Ni-Mg2Si/γ-Al2O3 were prepared. Their activities for catalytic hydroconversions (CHCs) of some lignite-related model compounds were examined. For the CHCs of oxydibenzene (ODB), benzyloxybenzene, and oxybis(methylene)dibenzene, the suitable loadings of Ni and Mg2Si are 33 and 20% in Ni-Mg2Si/γ-Al2O3, respectively, and the optimal reaction conditions are 4 MPa of initial hydrogen pressure, 240 °C, and 2 h, under which ODB was almost completely converted to cyclohexane. The formation of possible intermediates during the CHC of ODB was discussed. Ni-Mg2Si/γ-Al2O3 was proposed to have 3 functions, i.e., activating H2 to biatomic active hydrogen (H⋯H), releasing H−, and heterolytically splitting H⋯H to release H− as well, resulting in the hydrogenation of aromatic rings and the hydrocracking of CO bonds, respectively.