具有MWW结构钛硅分子筛的研究进展

Recent Advances in MWW-Type Titanosilicates

综述了具有MWW结构钛硅分子筛的制备方法、孔道和晶体结构的调变和修饰以及催化应用三个方面的研究进展.与TS-1相比,具有MWW结构钛硅分子筛的制备方法多种多样;其孔道结构可塑性强,通过采用层间剥离、柱撑以及分子水平硅烷化插硅扩孔技术,可以增大和暴露孔道和外表面,满足不同选择氧化反应的要求.由于MWW结构钛硅分子筛拥有复杂而独特的孔道结构,所以在小分子(如直链烯烃等)的环氧化反应,和大分子(环状烯烃,二苯并噻吩等)氧化反应中都表现出优异的催化性能.此外,该钛硅分子筛表现出与TS-1完全不同的溶剂效应,用于烯丙基氯液相环氧化与酮类氨氧化反应主产物选择性更高.

The progress in the preparation,structure modification,and catalytic applications in liquid-phase selective oxidations of MWW-type titanosilicates is reviewed.A novel titanosilicate with the MWW topology,Ti-MWW,has been prepared by various methods such as hydrothermal synthesis using boric acid as a crystallization-supporting agent,dry gel conversion,postsynthesis through reversible structural conversion,and dual structure-directing agents method.Ti-MWW,originating from a lamellar precursor,is readily subjected to various structural modifications,which leads to the catalytic materials with larger porosity suitable for a variety of oxidations.The unique pore and structure properties of Ti-MWW make it to be active and selective for the epoxidation of both linear and cyclic alkenes.Moreover,exhibiting a different solvent effect to TS-1,Ti-MWW shows more advantages in product selectivity in the ammoximation of ketones and epoxidation of alkenes with functional groups.