MWW族分子筛的结构研究进展

综述了MWW族分子筛结构研究进展。MWW族分子筛虽然具有相同的拓扑结构,但该族分子筛不同成员的微观结构仍有区别,因此用途各异。深入比较了MCM-22分子筛与MCM-49、MCM-56、MCM-36、ITQ-1和ITQ-2分子筛在微观结构上的区别,MCM-22(P)层间氧桥只有部分形成;MCM-22(C)层间氧桥完全形成;MCM-49(P)在2θ为6.5°处无衍射峰,在2θ为26°～29°范围内存在3个尖锐衍射峰;MCM-56(C)主要由约45%的单层晶胞晶体和约55%的二层晶胞晶体组成;MCM-36中的1.8nm×0.7nm的超笼由于支撑被分为两半;ITQ-2是由MCM-22(P)经扩孔制得的厚度为2.5nm的单层分子筛;无论是总比表面积(或介孔面积)还是孔容(或介孔孔容)均存在下列规律:即ITQ-2MCM-36MCM-56MCM-22。比较了MCM-22、MCM-49、B-MWW分子筛与Y及ZSM-5分子筛的IR光谱特征,评述了固体NMR和量子化学计算研究MWW族分子筛中骨架铝分布所取得的成果。MCM-22分子筛已经用作乙苯和异丙苯合成的工业催化剂,B-MWW分子筛在烯烃的环氧化反应中具有工业化前景。

Advances in MWW Zeolite Structure Research

This article describes the advances in the research of the structure of MWW zeolite.Although all MWW zeolite products have the same topology,different members in this family have different microstructures and thus they are used in different applications.This article compares MCM-22 zeolite and MCM-49,MCM-56,MCM-36,ITQ-1 and ITQ-2 zeolite to identify the difference in their microstructures and concludes that：①only partial interlayer oxygen bridge forms in MCM-22（P）;②the interlayer oxygen bridge fully forms in MCM-22（C）;③no diffraction peak is found where 2θ is 6.5° in MCM-49（P） and 3 sharp diffraction peaks are found where 2θ is between 26° and 29°;④MCM-56（C） mainly consists of about 45% single-layer unit cell crystal and about 55% double-layer unit cell crystal;⑤ he 1.8nm ×0.7nm supercage in MCM-36 is halved resulting from support;⑥ ITQ-2 is a single-layer zeolite with a thickness of 2.5nm,produced by reaming MCM-22（P）;⑦there is a law in both total specific surface area（or mesoporous area） and pore volume（or mesoporous pore volume） as follows：ITQ-2MCM-36MCM-56MCM-22.The article compares the IR spectral characteristics between MCM-22,MCM-49,B-MWW zeolite and Y and ZSM-5 zeolite and reviews the advances in solid NMR and in the research on the distribution of framework aluminum in MWW zeolite using quantum chemistry methods.MCM-22 zeolite has been applied as an industrial catalyst in the synthesis of ethylbenzene and cumene and B-MWW zeolite has sound prospect for commercial use in the epoxidation of olefin.