Developing a heating procedure to optimise hydrogen permeance through Pd-Ag membranes of thickness less than 2.2 μm
The Pd-Ag films, with a total thickness of <2.2 μm, were deposited by electroless plating on the inside of α-alumina membranes from SCT. The H2 permeances through separated Pd-Ag layers were poor and heating conditions were investigated to improve the H2 permeances through the metal films. The heating temperature, heating time and heating environment all had a significant effect on the H2 permeance and the H2 to N2 selectivity of the Pd-Ag films. The films were oxidised at 310°C for 1 h after heat treatment in Ar at 550°C, and then reduced in H2. This additional surface modification step more than doubled the H2 permeance through the film and only created a moderate amount of membrane defects as indicated by the increase in the N2 permeance. After the heating process, the membranes were characterised from 250 to 410°C using both a sweep gas and a positive pressure difference. © 2002 Elsevier Science B.V. All rights reserved.