Permeation of hydrogen through pre-oxidized Pd membranes in the presence and absence of CO

The main results of this investigation are: (a) Pd membranes activated by oxidization at 953 K have greater permeabilities than those oxidized in situ at approximate to523 K; the latter is in a commonly employed temperature range for activation/oxidation of Pd membranes, (b) it is shown quantitatively that the non-ideality of H dissolved in Pd accounts for the deviations of the permeabilities at higher pressures from a direct dependence on p(H2)(1/2), (c) the diffusion constants of H in Pd at infinite dilution obtained here agree well with those in the literature, (d) Pd membranes prepared by oxidization at 953 K are more resistant to CO poisoning than those oxidized in situ at 523 K, (e) the permeability of a Pd membrane (oxidation at 953 K) decreases over a 60 min period in the presence but not in the absence of CO, and (f) the CO poisoning increases as the temperature decreases. (C) 2003 Elsevier B.V. All rights reserved.