Vapor-Assisted Synthesis of Nanosized Beta-Zeolite from Natural Ores and Using as Efficient Catalysts for Baeyer–Villiger Oxidation
Jiwen Si, Ruifeng Guo, Fagui Qiu, Weikun Ning, Yanbin Sun, Wenqing Li, Qinglong Tao, Shiding Miao
Abstract
The nanosize Beta-zeolites with hierarchical structures were time efficiently synthesized from natural diatomite and ball clays under 150 °C via a vapor-assisted method with the absence of solvents and F – anions. The Sn(IV) species were incorporated within frameworks of the presynthesized Beta-zeolite using a modified treatment of acid and tetraethylammonium hydroxide (TEAOH). The dealumination and reconstruction of zeolite frameworks were essential. A high atomic ratio of Si/Sn = 63.95 was obtained and the Sn(IV) species were in a tetrahedral coordination in the zeolite framework, as confirmed by various characterizations. The Sn-Beta zeolites show excellent performance in the Baeyer–Villiger oxidation reaction for the conversion of cyclohexanone to ε-caprolactone, with 63.3% conversion of cyclohexanone and superior selectivity for ε-caprolactone. The durability and stability of the catalyst was acceptable, as evidenced by a slight decrease in conversion of only 2.5% after 5 catalytic runs. These demonstrated a prototype practice in synthesizing Sn-Beta zeolites from natural ores and applicable catalysis in green chemistry.