Abstract: A Sn-β zeolite was prepared by a two-step postsynthesis method. The procedure consists of first creating vacant T-sites with associated silanol groups by dealumination of Al-β zeolite with nitric acid and then impregnating the resulting Si-β zeolite with an aqueous solution of SnCl₄·5H₂O, followed by calcination at varying temperatures. The effects of the amount of vacant T-sites, SiO₂/Al₂O₃ ratio of Al-β zeolite and calcination temperature on the formation of the Sn-β zeolites and their catalytic performances for Baeyer-Villiger oxidation of cyclohexanone were investigated. The structure of the catalysts was characterized by X-ray diffraction, infrared spectroscopy, UV-Vis spectrophotometry, scanning electron microscopy, X-ray fluorescence spectrometry and inductively coupled plasma atomic emission spectrometry. The results show that, the Sn-β zeolite has been synthesized using a two-step postsynthesis method, and the Sn⁴⁺ ions are incorporated in the framework of the zeolite in a tetrahedral environment. The synthesized Sn-β zeolite shows impressive catalytic performance in Baeyer-Villiger oxidation of cyclohexanone using hydrogen peroxide as an oxidant.

Key words: tin, heteroatom zeolite β, cyclohexanone, Baeyer-Villiger oxidation, ε-caprolactone