Pt0.5?Snx/γ?Al₂O₃ catalysts with different Sn loads were prepared by constant volume sequential impregnation method and ultrasonic shock method to improve metal dispersion. The catalysts were characterized by XRD, BET, H₂?TPR, CO?IR and TG, and the effects of Sn content on the active center structure and propane dehydrogenation performance of Pt0.5?Snx/γ?Al₂O₃ catalysts were investigated. The results showed that adjusting the n（Pt）/n（Sn） by changing the Sn content in the samples would lead to the difference in the spatial distribution of Pt and Sn species, and thus affect the mode of action between Pt and Sn. With the increase of Sn, the interaction between Pt?Sn helps to increase the dispersion of Pt, the number of active sites, the improvement of the reaction activity of the catalyst. However, when excessive Sn is introduced, a Pt?Sn alloy is formed, resulting in the coating of Pt, resulting in a decrease in the number of active sites and a decline in the reactivity.

The hierarchical zeolite has become a hotspot in the current molecular sieve research field due to its advantages of efficient mass transfer and shape selection catalysis.The unclear mass transfer optimization mechanism has become a bottleneck restricting the design and development of hierarchical zeolite.This paper briefly introduces recent research and development status of the hierarchical zeolite,reviewes with emphasis the research progress in mass transfer mechanism of Hierarchical zeolite,the current research challenges and the analysis of current research strategy etc,and discussed the significance of mass transfer mechanism in the research and development of graded porous molecular sieve materials and the prospect of future development.