日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

Synthetic procedure and formation mechanisms of zeolitic membranes by a vapor-phase transport (VPT) method are described after crystallization techniques of zeolites by dry gel conversion are briefly introduced. In synthesizing zeolitic membaranes with good reproducibility by the VPT method, conditions for forming a dry aluminosilicate gel thin layer on a porous support are essential. A compact composite layer of zeolite and porous alumina can be formed by the VPT method because zeolite is crystallized in the pores of support. It is possible to synthesize a preferentially oriented zeolitic membranes by the selection of alumina source. Co-adsorption, the rate of molecules entering into zeolitic pores, and molecular sieving property as well as permeation through pinholes significantly influence the permeation and separation properties of zeolitic membranes. It is, thus, difficult to predict separation properties for multicomponent mixtures by using the results of permeation tests for unary systems. Further progress of zeolitic membrane synthesis and its utilization requires fundamental research in broad fields of science such as sol-gel sciece of aluminnosilicate systems, and adsorption and diffusion of molecules in zeolitic pores, other than crystallization of dry gels to zeolites.