Promising Strategy to Synthesize ZSM-5@Silicalite-1 with Superior Catalytic Performance for Catalytic Cracking Reactions
Hongyu Shen, Min Liu, Junjie Li, Xiujie Li, Sujuan Xie, Fucun Chen, Longya Xu, Xinwen Guo, Chunshan Song, Xiangxue Zhu
Abstract
The core–shell ZSM-5@silicalite-1 with regular morphology was prepared through an innovative tandem synthesis strategy for the first time, which combined the insertion of almost all aluminum sites by organotemplate-free synthesis and the sequential crystallization of residual silica sites by organotemplate-oriented synthesis. Samples with different Si and Al distributions could be synthesized by adjusting the tandem synthesis process, including temperature, time, Na2O/SiO2, etc. The obtained Si-rich-ZSM-5 and conventional C-ZSM-5 with a similar Si/Al ratio but different Al distributions, which were demonstrated by X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), and 1,3,5-triisopropylbenzene catalytic cracking analysis, were employed in n-hexane catalytic cracking reaction. Si-rich-ZSM-5 showed a higher stability with a n-hexane conversion of 57.7% at 100 h compared with that of C-ZSM-5 (24.6%), which was attributed to its inactive outer shell. Besides, a high para-xylene selectivity in xylene for the Si-rich-ZSM-5 catalyst was obtained. Hence, this study provides a simple and cost-effective strategy to fabricate highly stable catalysts for cracking reactions.