A Study On The Synthesis Of MSE-Type Heteroatomic Zeolites And Their Catalytic Performance

Heteroatom-containing zeolites is a kind of zeolites containing transition metal elements or main-group elements in the framework.It can not only play the special catalytic performance of transition state metal heteroatom,but also make the pore structure of zeolites can be used,which opens up a new application field for zeolite.In this paper,the construction,modification and catalytic application of MSE-type heteroatom-containing zeolites were studied based on the new molecular sieves with MSE topological structure.In the first part,Sn-MSE was synthesized by the treatment of dealuminated Al-MSE with gas-solid atom implantation method,and their physicochemical properties were characterized.The results show that the synthesis mechanism of Sn-MSE zeolite includes two steps.The first step is that a larger number of silanol nests are formed by the removal of the framework Al species from Al-MSE by the dealumination.In the second step,a reaction of D-MSE with Sn Cl₄ leads to the formation of framework Sn species.Combined with water vapor adsorption characterization,Sn-MSE has a higher hydrophilicity than Sn-BEA.Finally,the catalytic performance of Sn-MSE with high hydrophobicity was evaluated in the Baeyer-Villiger oxidation of 2-adamantanone and cyclohexanone,showing the TOFs of 147 h^-1 and 62 h^-1,respectivelywhich are higher than that of other stannosilicates.Finally,the stability and reusability experiments show that Sn-MSE zeolite has high stability and maintains its catalytic activity after five recycle experiment.Moreover,the Sn content in the used catalyst remains unchanged.Therefore,Sn-MSE zeolite is a renewable catalyst for the Baeyer-Villiger oxidation.In the second part,hierarchical MSE-type titanosilicate zeolites（Meso-Ti-MSE）and microporous MSE-type titanosilicate zeolites（Micro-Ti-MSE）were prepared by the combination of acid treatment,alkaline treatment and gas-solid atom implantation.The Meso-Ti-MSE and Micro-Ti-MSE zeolites were characterized by TEM and N₂adsorption-desorption.Finally,the catalytic performances of the Meso-Ti-MSE and Micro-Ti-MSE zeolites were evaluated by the hydroxylation of phenol with peroxide.The results show that Meso-Ti-MSE zeolite has a better catalytic performance than Micro-Ti-MSE zeolite in the hydroxylation of phenol with peroxide due to its more open pore system.