Proposal of Highly Separation Process by Using Zeolite Membrane with Highly Controlled Diffusion Mechanism

本研究的主要目的是开发一种在酸性溶液中表现出高分离性能的沸石膜。主要结果如下所述。a）具有亲水性质的Silicalite-1：提出了一种称为液相氧化法的方法，用于在具有过氧化氢的水溶液中去除所制备的高硅质MFI型沸石（Silicalite-1）晶体中的模板分子。通过该方法处理的Silicalite-1具有许多硅醇基团，并且显示出高亲水性，导致水分子通过氢键形成刚性网络，其中水分子被选择性地允许通过。B）沸石纳米晶体的制备：首先，通过使用TEOS、模板分子、表面活性剂、水和有机溶剂形成微乳液。将该乳液水热处理以产生MFI型沸石的单分散纳米晶体。c）制备具有高分离性能的沸石膜：首先，通过方法B）制备Silicalite-1的纳米晶体。然后通过方法a）处理晶体以产生具有亲水性质的Silicalite-1的纳米晶体。将由此获得的晶体堆积在氧化铝陶瓷过滤器上，并进行水热处理以将晶体固定在过滤器上，从而制备沸石膜。将该膜应用于丙酮/水和乙酸/水溶液的渗透汽化。对水的分离因子为无穷大，并且对水的渗透比没有任何针孔的沸石膜快100倍。

The main objective of this research is to develop a zeolite membrane showing high separation performance in acidic solution. The major results are described below.a)Silicalite-1 with hydrophilic properties : A method, called liquid phase oxidation method, was proposed for removing template molecules in as-prepared high siliceous MFI-type zeolite (Silicalite-1) crystals in water solution with hydrogen peroxide. Silicalite-1 treated by this method has many silanol groups in it, and showed high hydrophilic properties, leading to a rigid network of water molecules by hydrogen bonds, in which water molecules are selectively allowed to pass through.b)Preparation of nano-crystals of zeolites : First, a micro emulsion was formed by using TEOS, template molecule, surfactant, water and organic solvent. This emulsion was hydrothermally treated to yield mono-dispersed nano-crystals of MFI-type zeolite. The crystal size could be controlled in the range of 60 to 300nm.c)Preparation of zeolite membrane with high separation performance : First, nano-crystals of Silicalite-1 were prepared by the method b). Then the crystals were treated by the method a) to yield nano-crystals of Silicalite-1 with hydrophilic properties. The crystals thus obtained were piled on an alumina ceramic filter and hydrothermally treated to fix the crystals on the filter, producing the zeolite membrane. This membrane was applied to the pervaporation of acetone/water and acetic acid/water solutions. The separation factor for water was infinite, and the permeance for water was faster than that of a zeolite membrane without any pinholes by 100 times.