Catalysts Ni/y-Al2O3. Mg2Si/gamma-Al2O3, and Ni-Mg2Si/gamma-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/gamma-Al2O3, respectively, and the optimal reaction conditions are 4 MPa of initial hydrogen pressure, 240 degrees 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/gamma-Al2O3 was proposed to have 3 functions, i.e., activating H-2 to biatomic active hydrogen (H center dot center dot center dot H), releasing H-, and heterolytically splitting H center dot center dot center dot H to release H- as well, resulting in the hydrogenation of aromatic rings and the hydrocracking of C-O bonds, respectively. (C) 2017 Elsevier Ltd. All rights reserved.