Exploring suitable ZSM-5/MCM-41 zeolites for catalytic cracking of n-dodecane: Effect of initial particle size and Si/Al ratio

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• 作者：Guozhu Li¹ ; ² ; Zhenheng Diao¹ ; Jindan Na¹ ; Li Wang¹ ; ² ; ^{wlytj@tju.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：ZSM-5/MCM-41 ; Zeolite ; Desilication ; Recrystallization ; Catalytic cracking
• 刊名：Chinese Journal of Chemical Engineering
• 出版年：2015
• 出版时间：October 2015
• 年：2015
• 卷：23
• 期：10
• 页码：1655-1661
• 全文大小：994 K

文摘

In this study, various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkali-desilication and surfactant-directed recrystallization of ZSM-5. The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied. The results of XRD, TEM N₂-adsorption–desorption, NH₃-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3–4 nm pore size were formed around ZSM-5 crystals, and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5. Catalytic cracking of n-dodecane (550 °C, 4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance, with the improvement higher than 87% in the catalytic activities and 21% in the deactivation rate compared with untreated zeolites. This could be ascribed to their suitable pore structure, which enhanced the diffusion of reactant molecules in pores of catalysts.