杂原子Sn-β分子筛的脱铝补位两步法制备、表征及其催化环己酮Baeyer-Villiger氧化性能

Preparation and Characterization of Sn-β Zeolites by a Two-Step Postsynthesis Method and Their Catalytic Performance for Baeyer-Villiger Oxidation of Cyclohexanone

采用酸处理Al-β脱铝以产生T"空位",再高温焙烧插入Sn,即脱铝补位两步法制备了杂原子Sn-β分子筛.考察了β沸石中T"空位"数量、母体硅铝比和焙烧温度等因素对Sn-β分子筛形成与性能的影响,并利用X射线衍射、红外光谱、紫外-可见光谱、扫描电镜、X射线荧光光谱和电感耦合等离子体原子发射光谱等手段及环己酮Baeyer-Villiger(B-V)氧化反应,对催化剂进行了表征和评价.结果表明,脱铝补位两步法可以制备Sn-β分子筛,且Sn以四配位形式存在于分子筛骨架中,在对环己酮B-V氧化反应中表现出较高的催化活性.

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.