Hydrogen permeabilities (normalized fluxes), were measured for Pd and some Pd alloy membranes at a series of constant upstream H2 pressures, with the down-stream pressure being essentially 0, at 393 to 573K. From these data, activation energies for H permeation, EP, were determined (table 131). Permeabilities were also measured at a series of constant up-stream H concentrations, with the down-stream concentration being essentially 0. Under these conditions, the slopes of the Arrhenius plots gave activation energies which were equivalent to those for H diffusion. It was shown here that, under constant upstream pH2 conditions, non-ideality of the H led to non-linear Arrhenius plots of P for Pd and, especially, for some Pd alloy membranes where the H2 solubilities were significant even at moderate pH2. The permeabilities of a Pd0.77Ag0.23 alloy membrane and a Pd0.94Y0.06 alloy membrane were found to be almost independent of temperature at 423 to 523K, for constant up-stream pressures of 16.1 to 81kPa.

Temperature Dependence of H Permeation through Pd and Pd Alloy Membranes. T.B.Flanagan, D.Wang: Journal of Physical Chemistry A, 2012, 116[1], 185-92