(131a) Highly Selective Faujasite-Type Zeolite Membrane for Isopropyl Alcohol/Water Vapor Mixtures

In petrochemical industry, most of production processes involve distillation towers for dehydration of products such as various types of alcohol. Generally, distillation separation of water from products consumes a large amount of energy since vaporization of water requires a large amount of heat. Combination of a membrane separation unit with distillation can drastically reduce energy demand for the dehydration of alcohols. Faujasite-type zeolite is a kind of zeolite with both high stability in the presence of steam and strong hydrophilic nature. In this study, we investigated the preparation method of a compact faujasite-type of zeolite membrane, and separation properties were examined for mixtures of isopropyl alcohol(IPA)/water system. Faujasite-type membranes were prepared on the outer surface of tubular porous alumina support (o.d.= 10 mm, average pore diameter = 150 nm) by a secondary growth method including dip-coating of seed crystals and successive hydrothermal synthesis using aluminosilicate hydrogel. Vapor permeation and separation measurements were performed using a stainless steel tube module cell. By optimizing conditions for the dip-coating of seed crystals on the tubular support, seed crystals suitably dispersed in the pores of alumina tube. A compact faujasite-type membrane was formed by growing such seeds supported inside the pores of tubular support. The faujasite-type membrane developed in this study highly separated water from water/IPA mixtures. In the case of an mixture of water/IPA (20/80 wt/wt), the membrane showed a large flux of water of ca.1x10^-6 mol m^-2 s^-1 Pa^-1 with a high separation factor of water/IPA exceeding 3000 at 373 K.