Vapor-Assisted Synthesis of Nanosized Beta-Zeolite from Natural Ores and Using as Efficient Catalysts for Baeyer–Villiger Oxidation

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.