Hydrogen permeation through metal membranes at low upstream pressures was considered in the regime where the permeation rate was limited by the surface processes and not by diffusion in the bulk. The mathematical model for the H permeation through asymmetric membrane in the surface-limited regime was briefly introduced. For this model, it was shown that it was not possible to determine the unknown H-related membrane parameters by measuring the permeation flux through the membrane only in one direction. As an alternative to experiments on permeation in both directions, an innovative and simple experimental technique was described that permitted measurement of the permeation and out-gassing rates of the membrane. All of the fluxes were determined from the up-stream pressure change. A mathematical model and procedure were developed which permitted the extraction of all H-related membrane parameters from experimental data without fitting, solution of differential equations or reliance on published parameters. The error of the obtained parameters introduced by the calculation procedure was only a few %.

Determination of Parameters in Surface Limited Hydrogen Permeation through Metal Membrane. B.Zajec, V.Nemanič: Journal of Membrane Science, 2006, 280[1-2], 335-42