Fluid catalytic cracking (FCC) has been the primary processing technology for heavy oil. Due to the inferior properties of heavy oil, an excellent performance is demanded of FCC catalysts. In this work, based on the acid extracting method, Si-modified pseudo-boehmite units (Si-PB) are constructed in situ and introduced into the structure of kaolin to synthesize a Si-PB@kaolin composite. The synthesized Si-PB@kaolin is further characterized and used as a matrix material for the FCC catalyst. The results indicate that, compared with a conventional kaolin matrix, a Si-PB@kaolin composite could significantly improve the heavy oil catalytic cracking performance of the prepared FCC catalyst because of its excellent properties, such as a larger surface area, a higher pore volume, and a good surface acidity. For the fresh FCC catalysts, compared with the FCC catalysts using conventional kaolin (Cat-1), the gasoline yield and total liquid yield of the catalyst containing Si-PB@kaolin (Cat-2) could obviously increase by 2.06% and 1.55%, respectively, with the bottom yield decreasing by 2.64%. After vanadium and nickel contamination, compared with Cat-1, the gasoline yield and total liquid yield of Cat-2 could increase by 1.97% and 1.24%, respectively, with the bottom yield decreasing by 1.80 percentage points.
Keywords: FCC catalyst; Si modification; catalytic cracking; composite; kaolin; matrix material; pseudo-boehmite.