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具有高分离性能的分子筛膜。主要结果如下：a)具有亲水性的Silicalite-1：提出了一种用过氧化氢去除高硅量MFI型沸石(Silicalite-1)晶体中模板分子的方法。这种方法处理的Silicalite-1分子筛中含有大量的硅醇基团，并表现出高的亲水性，通过氢键形成了一个刚性的水分子网络，其中的水分子被选择性地允许通过。b)沸石纳米晶的制备：首先，以正硅酸乙酯、模板分子、表面活性剂、水和有机溶剂为原料形成微乳液。该乳液经水热处理后得到单分散的MFI型沸石纳米晶体。C)制备具有高分离性能的沸石膜：首先，用b)方法制备了纳米Silicalite-1晶体。然后用a)方法对晶体进行处理，得到具有亲水性的Silicalite-1纳米晶体。将得到的晶体堆积在氧化铝陶瓷过滤器上，并进行水热处理，将晶体固定在过滤器上，生成沸石膜。将该膜应用于丙酮/水和醋酸/水溶液的渗透汽化。对水的分离系数为无穷大，对水的渗透速度比无针孔沸石膜快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.