Rational construction of multiple hollow silicalite-1 zeolite with enhanced quasi acidity for robust vapor-phase Beckmann rearrangement
Peng Zhang, Xianfeng Yi, Changjiu Xia, Xinxin Peng, Shuai Zhang, Chengxiang Li, Anmin Zheng, Xiaoxin Zhang, Yibin Luo, Lifeng Cui, Fuhong Yu, Xingtian Shu
Abstract
Developing efficient and stable zeolites for vapor-phase Beckmann rearrangement of cyclohexanone oxime is still a great challenge to realize ε-caprolactam (CPL) green production. In this work, the hierarchical porous silicalite-1 zeolites with multiple hollow structure (S-1-M) are explored by in-situ desilication—recrystallization post-treatment of spongy highway-like zeolites (S-1-S), which are synthesized through silanization synthesis of conventional bulky silicalite-1 (S-1). Compared to S-1, S-1-M achieves superior catalytic performance, with improving the CPL selectivity from 85.7% to 94.1% and prolonging the catalyst lifetime from 74 to 126 h at a weight hourly space velocity (WHSV) of 6 h−1. Comprehensive physiochemical studies demonstrate that the highly dispersed intracrystalline cavities within S-1-M endow greater mass diffusion and better quasi acidity inducing by the enhanced H-bonds among abundant H-bonded silanols, which is cooperatively responsible for its superior catalytic performance.