Abstract
A thermo- and steam- stable silica membrane was prepared by a counter diffusion chemical vapor deposition method using tetramethyl orthosilicate (TMOS) and O2 as reactants at 873 K. H2 permeance at 873 K permeation test was 1.5 x 10-7 mol m-2 s-1 Pa-1, and H2/N2 permeance ratio was ca. 1000. H2/N2 permeance ratio was kept for 21 h under H2O/N2 ratio = 3 at 773 K that is the typical methane steam reforming conditions for a membrane reactor. 3 pieces of alumina tube substrates were welded by amorphous glass for a module and treated by the CVD at the same time. H2/N2 permeance ratio was over 3000 for the 3 membrane modules with the membrane gaps of 1.8 mm. This shows that uniform treatment was conducted on 3 substrates in the module by the counter diffusion CVD.
