偏高岭土水热合成4A沸石晶化行为的研究

以偏高岭土为原料合成4A沸石，由于其合成过程工艺简单，成本低而一直受到普遍的关注，对于该法晶化过程的行为研究，近年来陆续出现报道，Rocha等^1]研究认为偏高岭土在碱液中缓慢溶解，形成含SiO3^2-,SiOH基团和Al(OH)4^-的溶液，逐步缩合为硅铝酸钠凝胶，再进一步形成4A沸石晶粒并通过结构重排而转变为4A沸石，王建等^2]研究提出偏高岭土在NaOH溶液中部分溶解，且迅速转变为偏高岭土，并伴有硅铝酸钠凝胶产生，同时偏高岭土也不断在碱液的作用下凝胶化，生成的凝胶再进一步转变为4A沸石，因而合成的4A沸石产品与化学合成法存在着较大的差异。对偏高岭土合成4A沸石的晶化历程，作者曾进行过研究^3]，发现偏高岭土在碱液中溶解很小，由偏高岭土转为4A沸石晶型，主要是在偏高岭土固相的基础上进行的。本文似从合成过程的机理方面，探讨偏高岭土合成4A沸石的晶化过程行为及其与化学法合成产品差异的关键所在。

A Study of Crystallization of Zeolite 4A Prepared by MetaKaolinite

The Crystallization of Zeolite 4A from MetaKaolinite was studied by chemical analysis, FT IR, XRD and SEM. The results show that the Crystallization of Zeolite 4A is primary solid phase transform mechanism. It is found that the Cage Shaped crystal nucleus embryos are firstly formed in the lye of metakaolinite, then the Cage Shaped crystal nucleus embryos are put in order and the crystal of Zeolite 4A is taken shape, Because the metakaolinite method and Chemical Synthesis method have different forming mechanism, the difference of Zeolite 4A on performance is caused.