Core-shell-structured Composite ZSM-5@MCM-41 Catalysts:Fabrication,Characterization,and Enhanced Performance in Hexane Catalytic Cracking  

作　　者：Zhu Jiale Zhu Xuedong Yang Fan 

机构地区：[1]State Key Laboratory of Chemical Engineering,School of Chemical Engineering,East China University of Science&Technology,Shanghai 200237,China

出　　处：《China Petroleum Processing & Petrochemical Technology》2023年第4期41-51,共11页中国炼油与石油化工（英文版）

基　　金：sponsored financially by the National Natural Science Foundation of China (Grant No. 21776076);the Fundamental Research Funds for the Central Universities (Grant No. JKA01211710)。

摘　　要：A series of core-shell zeolites with a ZSM-5 zeolite core and a MCM-41 shell with varying shell thicknesses were successfully fabricated via a cetyltrimethylammonium bromide(CTAB)-directed sol-gel coating method in an ultradilute solution. Extensive characterization techniques, including XRD, TEM, N_(2) adsorption-desorption, NH_(3)-TPD, and IR measurements, confirmed the successful coating of a microporous ZSM-5 core with a mesoporous MCM-41 shell layer and were further employed to explore the textural properties and acidic properties of the samples. The hexane cracking results revealed a significant enhancement in olefin yields after introducing the MCM-41 shell to ZSM-5. Interestingly, a volcanic trend in olefin yields was observed with the increase in the shell thickness. In particular, the highest olefin yield of 51.5%, exceeding that of the core catalyst by 17.1%, was achieved when the shell thickness was controlled at 40 nm.Moreover, the catalyst lifetime investigation revealed that the core-shell composite catalyst exhibited a minimal reduction in hexane conversion of merely 3.8% over a 120 h reaction period, significantly outperforming the 11.3% reduction exhibited by the core catalyst. This remarkable catalytic performance was attributed to the passivation of external acid sites and the introduction of more developed pore channels by the shell, which effectively mitigated unwanted side reactions. The successful synthesis of these core-shell structured catalysts presents a novel strategy for improving catalytic performance in hexane cracking, in addition to serving as a solid foundation for the design of industrial catalysts for light naphtha cracking.

关 键 词：catalytic cracking light olefin CORE-SHELL ZSM-5 ZEOLITE 

分 类 号：TQ426[化学工程]