Hydrogen transport through a membrane module based on a palladium foil

Experimental data are presented and a mathematical model is suggested for hydrogen transport through a palladium membrane module. The basic working element of the module is a piece of palladium foil secured between two pieces of fine-mesh metallic gauze to prevent the rupture of the foil because of the difference between the outer pressures applied. It is demonstrated that, under the experimental conditions considered, the effect of the supporting metallic gauzes can be neglected. An expression is reported for the hydrogen flux through the foil as a function of the foil thickness and applied pressures. In the particular case of fairly high pressures, the hydrogen flux obeys the well-known Sieverts law, being limited by proton diffusion in the palladium lattice. At low pressures, the hydrogen flux is limited by adsorption-desorption processes on the foil surface. The preexponential factor in the Sieverts law for pure palladium membranes has been refined on the basis of experimental data for the membrane module.