Location of Alkali Ions and their Relevance to Crystallization of Low Silica X Zeolite
Location of Alkali Ions and their Relevance to Crystallization of Low Silica X Zeolite
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DOI：
10.1021/cg100289p
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发表时间：
2010-08-01
影响因子：
3.8
通讯作者：
Okubo, Tatsuya
中科院分区：
文献类型：
--
作者：
Iwama, Marie;Suzuki, Yasuhiro;Okubo, Tatsuya
提出了一种中间加入碱金属离子的新方法，使沸石在晶化阶段具有相选择性。碱金属离子在形成的沸石A，低硅沸石X（LSX），和它们的水凝胶的结晶前的位置进行了研究，以澄清的结晶机制，其中特定的碱金属离子是需要选择性生长的沸石的离子交换等温线。钾离子在结晶过程中的作用对决定晶体的最终物相有重要意义。水合钾离子具有通过强盐析作用组装铝硅酸盐前驱体形成LSX的功能，而钠离子则将相同的结构单元组装成A型沸石。在结晶介质中中间加入钾离子可从动力学上控制最终的沉淀结晶相。在这里，我们提出的方法使沸石A的结构单元被淬灭并沉积到铝硅酸盐水凝胶中，导致在水凝胶相中选择性地形成LSX。
A novel method of intermediate addition of alkali ions is proposed to give phase selectivity of zeolite in crystallization stages. Location of alkali metal ions in formed zeolite A, low silica zeolite X (LSX), and their hydrogel prior to the crystallization is investigated with ion exchange isotherms in order to clarify the crystallization mechanism, where the specific alkali metal ion is required for selective growth of the zeolites. The role of potassium ion for the crystallization is found to be important to determine the final phase of crystals. Hydrated potassium ion has a function to assemble aluminosilicate precursors to form LSX by a strong salting-out effect; otherwise, sodium ion assembles the same building units into zeolite A. Intermediate addition of potassium ion into crystallizing media controls the final precipitating crystalline phase kinetically. Here our proposed method enables the building unit for zeolite A to be quenched and deposited into aluminosilicate hydrogel, resulting in the selective formation of LSX in the hydrogel phase.