Abstract: With the transformation of energy structure, the demand and price of refined oil and chemical products in market fluctuate sinusoidally. The existing refining transformation technology is irreversible and the production plan cannot be flexibly adjusted to meet market demand. Controlling single-molecule and bimolecular reaction path at micro scale was an effective method to solve the problem of inflexibility in the transition from refining to chemical industry in FCC process. It was proposed that the bimolecular reaction index could be used as a proportional measure of the occurrence of single-molecule and bimolecular reaction. The reaction temperature and the type of molecular sieve catalyst were two significant variables affecting the yields of liquefied gas and gasoline. The results showed that the yields of gasoline and (propylene + butene) over Y zeolite catalyst at 530 ℃ were 47.55% and 13.31%, respectively, and the yields of gasoline and (propylene + butene) over MFI zeolite catalyst at 580 ℃ were 22.05% and 31.45%, respectively. The relationship between reaction temperature and catalyst type ratio and the yield of target products was obtained, and the idea of flexible switching and adjustment of industrial plant production scheme was proposed to form a flexible and efficient catalytic cracking process. The industrial application results showed that the production scheme switching of (propylene + butene) and gasoline could be completed within a few weeks. Flexible production scheme provides technical ideas for low-cost progressive transformation and development.

Key words: monomolecular reaction, bimolecular reaction, bimolecular reaction index, fluid catalytic cracking, Y zeolite, MFI zeolite