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

Pervaporation has attracted increasing attention as an effectives and energy efficient technique for separation of azeotropic or close-boiling liquid mixtures. Polymeric membranes have been widely investigated for pervaporation of these liquid mixtures. However, practical application of polymeric membranes has been limited to dehydration of alcohols because of insufficiency of their thermal, mechanical and chemical stability.

The recent development of hydrophilic zeolite membranes, which were derived on the surfaces of porous tubular supports composed of mullite, α-alumina and cristobalite using the hydrothermal synthesis, have made it possible to overcome the above limitations of hydrophilic polymeric membranes. These membranes are available in the form of cylindrical tubes 12 mm in outer diameter, 9 mm in inner diameter and 800 mm in length.

Two tubular-type modules (double tube-type module, tubular-type module) with many pieces of zeolite membrane, which have high pervaporation performance and can be purchased at a low price, were designed in order to make the zeolite membranes viable for industrial application. These membranes used in the two modules are sealed at one end of a support tube. The double tube-type module is composed of a membrane inserted in the steel tube and group of these modules are put in a vacuum vessel. In the tubular-type module, membranes sealed at one end of a support tube are inserted alternatively at the designated pitch from both tube sheet and fixed at the tube sheet.

In both modules, solvents are fed to the outer side of the zeolite membrane and the permeated gaseous mixture through the inside of membrane is collected by condenser.