X-ray diffraction study on the effects of hydrogen on Pd60Cu40 wt% foil membranes

An as-received Pd60Cu40 wt% foil membrane had been cycled between 50 and 450 °C under a 445 kPa feed pressure and 100 kPa permeate pressure of hydrogen. In the third cycle, this membrane achieved a noticeably low hydrogen permeability of 5.59 × 10−9 mol m−1 s−1 Pa−0.5 at 450 °C. Moreover, the partial pressure exponent was found to deviate significantly from Sieverts' law between 400 and 450 °C. Subsequently, this membrane was cycled twice between 250 and 700 °C achieving a much higher hydrogen permeability of 1.19 × 10−8 mol m−1 s−1 Pa−0.5 which was measured at 450 °C. The activation energy for permeation reduced by more than 60% and the partial pressure exponent decreased to 0.52. The initial poor hydrogen permeability of the membrane was attributed to coring as evidenced by the presence of the disordered FCC phase in the as-received foil. The improvement in hydrogen permeability was linked to the homogenisation effect of hydrogen under the conditions used in this study.