纳米沸石的合成、性质、组装及应用

Synthesis,Properties,Assembly and Application of Nanosized Zeolite

对纳米沸石的合成、理化性质以及在纳米组装和催化反应中的应用进行了综述。在纳米沸石的合成中 ,采用较低的晶化温度是得到纳米沸石的最主要的途径。与大晶粒的沸石相比 ,纳米沸石表现出一些独特的理化性质 ,如高的外比表面积、丰富的表面硅羟基和自聚集特性等。由于纳米沸石具有很好的单分散性、可调的表面电性质和自聚集性质 ,因此是一种理想的纳米“构建块” ,通过选择合适的模板可以组装出具有各种形貌和结构的多级孔道结构沸石材料。纳米沸石在一些催化反应中也表现出某些方面的独特性能 ,如高的活性。

This paper reviews the synthesis of nanosized silicalite-1,ZSM-5,TS-1,beta,A and Y zeolite.Low-temperature hydrothermal crystallization is the ideal approach for obtaining discrete zeolite colloids with crystal size of less than 100 nm.Other methods,such as confined-space crystallization,peso-solid phase crystallization etc.are also possible for obtaining zeolites with nanosized particles.Dispersed nanosized zeolites have typical colloidal properties such as high external surface area,abundant surface hydroxyl and self-aggregation properties.Zeta potential of colloidal zeolites changes with pH,zeolite composition,crystal size,and structures.The nanozeolites possessed some unique physico-chemical properties which are different from those of the large crystal zeolites.With high dispersibility and abundant surface hydroxyls,nanozeolites are perfect building blocks in nano-assembly technology.Using the assembly properties of nanozeolites,various hierarchical structured zeolite materials have been successfully fabricated.In some of the applications in catalyst field,nanosized zeolites also have the merits of high activity,long lifetime and special selectivity.