Hydrogen permeation across membranes was measured using a dynamic pressure difference method. In the method, a transient system for continuously monitoring hydrogen flux of a membrane was conducted. Three different membranes, consisting of two pure Pd membranes with different thicknesses and one Pd–Cu membrane supported by porous stainless steel tubes, were taken into account. Three different operating temperatures of 320, 350 and 380C as well as two different initial pressure differences of 5 and 10 atm were considered to evaluate the effects of the operating parameters upon the hydrogen permeation. The results suggested that a threshold of pressure difference was always exhibited at the end of the permeation process, regardless of which membrane was tested. The hydrogen permeation rate could be predicted well for the pressure exponent in the range of 0.1 to 1.0; however, the optimal pressure exponent was located between 0.5 and 0.8. The theoretical analysis indicates that the characteristic time of hydrogen permeation in the present system ranges from 245 to 460s and the entire permeation period was longer than the characteristic time by an order of magnitude. In regard to the effect of membrane temperature on the permeation, the activation energies of the three membranes range from 11 to 18kJ/mol.

Hydrogen Permeation Measurements of Pd and Pd–Cu Membranes using Dynamic Pressure Difference Method. W.H.Chen, P.C.Hsu: International Journal of Hydrogen Energy, 2011, 36[15], 9355-66