Preparation of palladium-silver alloy composite membranes for hydrogen permeation

Abstract

Pd-Ag/α-alumina composite membranes were fabricated by electroless plating technique. Permeability measurements were performed with hydrogen and nitrogen at temperatures ranging from 423 to 616 K and pressures ranging from 80 to 250 kPa. The results confirmed that the skin layers of prepared membranes were not defect-free. The ideal separation factor of H 2 /N 2 through Pd 0.9 -Ag 0.1 composite membrane ranged from 30 to 178 under the present experimental conditions. Furthermore, a resistance model was used to account for the simultaneous transport of hydrogen through the defects as well as the bulk Pd-Ag alloy film in Pd 0.9 -Ag 0.1 composite membrane. It revealed that the transport mechanism for hydrogen in this membrane was a combination of solution-diffusion and Knudsen diffusion with minimal contribution of viscous flow.