Synthesis and characterization of hydrogen-selective sol-gel SiO2 membranes supported on ceramic and stainless steel supports

Novel microporous membranes were developed on porous ceramic and stainless steel supports to separate H2 from CO2 or N2. An extensive synthesis and characterization study was carried out, which yielded novel processing routes for microporous membranes. Examples in this article include rapid thermal processing (RTP), ink-jet printing, and a route for fabricating metal-supported microporous membranes. Pure SiO2 membranes prepared under optimized cleanroom conditions exhibited a reproducible high selectivity for He and H2 towards CO2 and N2 (e.g. average αH2/CO2>70;αH2/N2>150). Microporous membranes prepared with RTP, with an overall processing time of approximately 1 h for the microporous top layer, showed a similar gas permeance and high selectivity. Another breakthrough compared to the state of the art is the introduction of a gas-selective metal-supported microporous membrane. The first prototypes, which were fabricated with a commercial stainless steel filter material as support material, exhibited a comparably attractive selectivity for H2 (e.g. αH2/CO2∼50). Ni- and Co-doped membranes were additionally prepared in this study, since they are recognized as a membrane type with improved stability towards water vapour.