Abstract: In order to improve the properties and catalytic cracking performance of USY zeolite modified by conventional “Hydrothermal hyperstability” process, the conventional “Two-exchange-two-calcination” process was combined with in-situ silica modification method, and the silica-rich USY zeolite was prepared and used for the preparation of FCC catalyst, which was characterized by XRD, N₂ adsorption-desorption, NH₃-TPD, SEM and so on, and the performance of the FCC catalyst was evaluated by ACE unit. The results showed that the crystallinity, crystal lattice parameter, specific surface area, pore volume, surface acidity and micro cracking activity of surface silica-rich USY zeolite were better than those of conventional USY zeolite. Compared with the FCC catalyst made by conventional USY zeolite, the conversion of heavy oil cracked on the FCC catalyst prepared by USY zeolite with silicon-rich surface increased by 3.70 percentage points, and the yield of gasoline and the total yield of liquid products increased by 2.31 percentage points and 1.32 percentage points, respectively, which indicate that the FCC catalyst prepared by USY zeolite with silicon-rich surface layer has excellent catalytic performance.

Key words: surface silica-rich, USY zeolite, catalyst, catalytic cracking