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

Zeolite and molecular sieves are widely used in many chemical processes such as heterogeneous catalysis and gas or liquid separation. Recently, great interest has been focused on zeolite films due to their uniform pore sizes and resistance to high temperatures. More recently, we succeeded in preparing polycrystalline zeolite films of ZSM-5, silicalite, ZSM-11 and SAPO by using a Teflon slab, a filter paper and a porous substrate. As the Al distribution and the change in the morphology along the width of film reflected the time course of the crystal growth, we could get much information regarding the crystal growth process by analyzing the film obtained. It was found that the polycrystalline zeolite films are formed through a successive accumulation of zeolite crystals. It was also found that during the initial crystallization of zeolite, the zeolite crystals with high SiO₂/Al₂O₃ ratios are generated.

Next, we investigated the liquid separation potential of the zeolite film. Separation of ethanol/water mixture was carried out by pervaporation through the silicalite film on a porous stainless steel support. It was found that the film has the high ethanol permselectivity with a separation factor α(EtOH/H₂O) of approximately 60 compared to various membranes reported up to now, indicating that the silicalite film is effective for alcohol concentration process.