Abstract
Hydrogen permeselective silica membranes prepared by using a counter diffusion CVD method had been investigated in the effects of deposition temperatures and those of γ-alumina substrates. Hydrothermal stable silica membranes were obtained between 550 and 600 ℃ of deposition temperatures for the TMOS (tetramethyl orthosilicate)/ O2 system. Silica layer deposited at the lower temperature was damaged due to compaction of the deposited silica, while γ-alumina layer (support of the silica layer) must be damaged for the higher deposition temperature. Addition of Ga to γ-alumina is one idea to improve the stability of the support. As a result, decrease of hydrogen permeance through the silica membrane by hydrothermal treatment was reduced. It is important to improve support stability to improve the permeation properties of the silica layer deposited on the support.
