Review of Silica Membranes for Hydrogen Separation Prepared by Chemical Vapor Deposition

The application of inorganic silica membranes for sulfur hexafluoride selectivity separation at elevated temperatures has attracted much attention due to their good permselectivity and mechanical strength. These membranes are usually in the form of a thin layer of silica (selective layer) deposited on a thick porous support. One of the methods which is successfully used for deposition of the silica layers is the chemical vapor deposition (CVD), due to its versatility and reproducibility as well as high selectivities obtained with the membranes formed by this method. This chapter starts with a brief description of the basic principles of CVD and its application in the preparation of silica membranes, followed by a complete literature review which surveys the studies that have been carried out on supported silica membranes prepared through CVD and applied in hydrogen separation with two of the most commonly used supports, Vycor glass and alumina.