Pore Size Control and Separation Mechanism of Inorganic Membranes.

Abstract

This article reviews recent research works on inorganic membranes for gas separation. Porous silica membranes with H2/N2 selectivities higher than 1,000 have been produced by chemical vapor deposition and sol-gel methods and applied to membrane reactors and hydrogen recovery processes at elevated temperatures. Carbon membranes developed recently show high O2/N2 selectivities at high permeation rates. Oxygen ion-conductive dense membranes as well as CO2-selective porous membranes have been also realized. The high permeation of CO2 through Y-type zeolite membranes is explained in terms of surface diffusion which is sensitive to pore dimensions.