菱沸石分子筛膜的合成调控与气体分离研究进展

Synthesis and Gas Separation of Chabazite Zeolite Membranes

菱沸石(Chabazite,CHA)分子筛膜因其八元环小孔(0.38 nm)三维孔道结构、可调的表面特性、较高的材料稳定性与制备可重复性,在轻质气体分离方面具有优异性能,近年来逐渐成为分子筛膜研究热点之一。本综述介绍了两种CHA分子筛膜(SAPO-34膜、SSZ-13膜)的基本特性,对比了CHA分子筛膜的合成方法(原位合成法、二次生长法、微波加热法)优缺点及其应用现状,并重点针对主流的二次生长法制备SSZ-13膜与SAPO-34膜过程中关键条件对薄膜质量的影响规律进行了详细阐述,包括铺种条件(载体种类、晶种类别、铺种方式),水热合成条件(晶化时间、晶化温度、含水量、硅铝比、模板剂、阳离子种类)与煅烧方式(常规煅烧、分段煅烧、快速热处理),经细化分析总结出上述两种膜的优选合成条件;并进一步汇总了CHA分子筛膜表面化学调控(硅铝比调控、阳离子交换、杂原子替换、氨基功能化、表面修饰)对气体分离增强的策略,总结了CHA分子筛膜在各种气体体系中的分离特点与单组分气体渗透特性。最后,对CHA分子筛膜今后的发展和应用前景进行了展望。

Chabazite(CHA)zeolite membranes exhibit superior performances in light gas separations owing to the eight-membered ring channel structure with small pore size(0.38 nm),adjustable surface characteristics,and high material stability and preparation reproducibility,and have gradually become one of the hot spots of zeolite membrane research in recent years.This review article first introduces the basic characteristics,the two typical CHA zeolite membranes(SAPO-34 and SSZ-13 membranes),then compares the synthesis and preparation methods of CHA zeolite membranes(in-situ synthesis,secondary growth synthesis,microwave heating methods)and analyzes their advantages and disadvantages in application status.The influences of their key synthesis conditions of the secondary growth as the mainstream synthesis method on the qualities of SSZ-13 and SAPO-34 membranes have been elaborated in detail,mainly including 1)the seeding conditions,such as carrier type,seeding crystal and seeding approach;2)the hydrothermal synthesis conditions,such as crystallization time and temperature,water content,silica-to-alumina ratio,structure directing agent,and cation type;3)the calcination approaches,such as conventional calcination,staged calcination,and rapid heating treatments.After comparative analysis,the preferred synthesis conditions of the above two typical CHA zeolite membranes are proposed.Furthermore,the modulation of membrane surface chemistry is discussed for the enhancement in gas separation,such as silica-to-alumina ratio adjustment,ion exchange,heteroatom substitution,amino-group functionalization,and surface modification.The detailed characteristics of gas separation in various gas mixture systems and the permeation properties of different single gases on CHA zeolite membranes are analyzed and summarized as well.Finally,the future development of CHA zeolite membranes is prospected.