Dependence of hydrogen flux on the pore size and plating surface topology of asymmetric Pd-porous stainless steel membranes

The influence of the support properties on the characteristics of Pd/PSS composite membranes has been evaluated for a large group of membrane samples prepared by electroless plating. The H-2 permeation in the membranes was found to follow Sievert's law between 325-500degreesC. The steady state H-2 flux was-stable for over 200 h. The hydrogen permeance was measured at 350degreesC with a 1-atm pressure difference and ranged from 20.0 to 5.1 m(3)/(m(2z).h.atm(0.5)) for a Pd layer thickness of 11.7 and 33.8 mum, respectively. The thickness of the membranes and therefore the permeance obtained was dependent on the size of the largest pores present in the support. The thickness of the Pd layer was approximately three times the dimension of the largest pores in the support, consistent with the previous theoretical results of Ma et al. [3].