The effects of gas mixtures on hydrogen permeation through Pd-Ag/V-Ni alloy composite membrane

The effects of gas mixtures on hydrogen permeation through Pd-Ag coated V-Ni composite membranes were investigated by gas permeation technique in the temperature range of 473-673 K at atmospheric pressure. Dense Pd-25Ag layer was sputtered on the V-15Ni alloy film prepared by arc-melting. Hydrogen permeation experiments for as-prepared Pd-Ag/V-Ni composite membrane were carried out with pure hydrogen and different gas mixtures of H(2)/CO(2) and H(2)/H(2)S. Long-term permeation tests were performed with the mixture feed of 30%-CO(2) in H(2) and 11 ppm-H(2)S in H(2). As the percentage of gas impurity increased, the hydrogen permeability decreased. However, the composite membrane did not suffer irreparable damage when exposed to CO(2) and the flux value for pure hydrogen was readily recovered by post-treatment in the permeation system. For the H(2)S impurity, the interaction with the membrane surface was significantly different compared to CO(2). Membrane permeability rapidly deteriorated when exposed to a small percentage of H(2)S. Nevertheless, the membrane does not seem to be damaged as the permeability was fully recovered by longer post-treatment with pure hydrogen. (C) 2011 Elsevier B. V. All rights reserved.