Abstract: Hydrocracking catalysts with different metal distribution were prepared by impregnation method, where the metals were loaded on ① mixture of Y, β zeolite and amorphous silica-alumina, or ② on SiAl first and then mechanically mixed with Y and ? zeolite mixture, respectively. The effect of metal and acidity distribution on the pore structures, acidity, and hydrocracking performance of the catalyst prepared by two different methods was investigated. The results show that the surface area and acidity are slightly lowered by the second way, compared with the first method. It is proved that shorter distance between metal and acidic center is favorable to the diffusion of reactant from acidic center to metal center, resulting in higher conversion rate, light oil selectivity and the yield of chemical raw materials, while the liquid yield is relatively lower.

Key words: hydrocracking, acid center, metal center, catalyst