Abstract: In this study, ZSM-5 zeolites were synthesized via the hydrothermal method using sodium metaaluminate,sodium hydroxide,pseudo-boehmite and aluminum isopropoxide as aluminum sources, respectively. Based on the characterization of physicochemical properties and the catalytic performance test of butene cracking, the effect of aluminum source types on the sitting of framework aluminum atoms and structure-activity relationship was investigated. The results showed that the type of aluminum source had little influence on the crystal structure, pore structure, surface morphology, and total acid amount of ZSM-5 zeolite. However, it exerted a significant effect on the distribution of framework aluminum atoms. In the research synthesis system, aluminum sources with higher solubility (e.g., sodium metaaluminate) compared to those with slower hydrolysis rates (e.g., pseudoboehmite and aluminum isopropoxide), the proportion of aluminum atoms located in the straight channels (α-sites) is increased. Due to spatial restriction, zeolites with a high proportion of framework aluminum atoms located at α-sites exhibit high propylene selectivity in butylene catalytic cracking reaction.This study not only verified the structure-activity relationship between the acid site distribution of ZSM-5 zeolites furtherly, and also provided a basis for the directional synthesis of high-performance catalyst for butylene catalytic cracking.

Key words: molecular sieve, acid property, framework aluminum atom, propylene selectivity, hydrothermal synthesis method