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TitleHydrogen permeable membranes from palladium coated anodic alumina
Publication TypeBook
Year of Publication2010
AuthorsBrown, I.W.M., Wu J., Nelson M., Bowden M.E., and Kemmitt T.
Series TitleCeramic Transactions
Number of Pages1 - 16
ISBN10421122 (ISSN); 9780470881286 (ISBN)
KeywordsAcid electrolytes, Alloying metals, Alumina ceramic, Alumina template, Aluminum foil, Anodic alumina, Anodic alumina membranes, Anodizing voltage, Ceramic materials, Deposition, Electroless deposition, Gas permeable membranes, Gas separations, glass, High selectivity, High-purity, hydrogen, Hydrogen embrittlement, Hydrogen permeable membranes, Mixed gas, Nano-structured, Palladium, Palladium membrane, Palladium-silver alloy, Pd membrane, Permselectivities, Pore diameters, Porous anodic alumina, Silver, Silver alloys, Thermal cycling, Thin films
AbstractNanostructured anodic alumina membranes have been fabricated from templates prepared by anodizing annealed high-purity aluminum foil. A range of acid electrolytes and anodizing voltage profiles have been used to control the pore diameter, pore separation and thickness in these alumina ceramic templates. Thin films of Pd metal up to 200nm thick have been deposited on the surface of the alumina templates and we have demonstrated that the membranes formed can be used to separate hydrogen from mixed gas streams with very high selectivity. These pure Pd membranes experience hydrogen embrittlement in operation below 350°C and we have employed silver as an alloying metal to help prevent this. An electroless deposition technique was used to obtain thin films of palladium and silver on the porous anodic alumina substrate. The films were tested via thermal cycling and gas separation experiments. The palladium membrane showed clear cracks after thermal cycling while the palladium silver alloy membranes showed no obvious damage. Gas separation tests showed that a membrane with 30% silver displayed increasing permeance (flux) with increasing temperature, with H2/N2 permselectivity of ∼500 and permeance of ∼1.8 μmol/m2.s.Pa at 700°C.

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