Chromium oxide intermetallic diffusion barrier for palladium membrane supported on porous stainless steel

Dense palladium membrane on oxidized porous stainless steel (oxPSS) tube was prepared. Its hydrogen permeance was observed to decline at the temperature higher than 400 °C. SEM–EDX analysis of the cross-section of the annealed tube at 500 °C indicated the occurrence of the intermetallic diffusion. The heat treatment study of the palladium membrane on oxPSS disks in hydrogen atmosphere at various temperatures was essentially carried out. Their SEM–EDX analysis results confirmed that the in situ metal oxide barrier could not inhibit the intermetallic diffusion in hydrogen atmosphere. The chromium oxide layers at different thicknesses were then developed on oxPSS disks before palladium plating by controlled chromium elctrodeposition followed by oxidation in air at 700 °C. The similar heat treatment study and SEM–EDX analysis of these disks revealed that the presence of chromium oxide layer could suppress the intermetallic diffusion. Then, the dense palladium membrane tube with chromium oxide layer was prepared and its heat treatment in hydrogen atmosphere was studied. The result showed the steady increase in hydrogen permeance with increasing temperature.