Abstract: NiMoS hydrocracking catalysts containing sulfur precursors calcined under various temperatures were prepared by kneading method, using ammonium tetrathiomolybdate and nickel nitrate as active components, and composite support composed of γ-Al2O3 and modified zeolite Y. The properties of catalysts were investigated by FT-IR, XRD and TEM. Test results indicated that with the increase of calcination temperature, the total acidity of the catalysts with sulfur precursors increased firstly and then decreased; more medium strong acid amount and higher B/L value were observed for these catalysts as compared with the oxidation state catalyst. The interactions between metal component and support in the catalysts containing ammonium tetrathiomolybdate as sulfur precursor were weakened, thus suitable crystal sizes and stacking numbers of active metal components could be obtained and the catalytic performances of the catalysts were improved. However, exceeded high calcination temperature was not in favor of forming suitable average crystal size and stacking number of MoS2 active phase. Catalyst with sulfur precursors calcined at 500 ℃ exhibited good hydrocracking performance: high conversion and liquid yield, as well as high selectivity and outstanding isomerization performance.

Key words: hydrocracking, catalyst, ammonium tetrathiomolybdate