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Hydrogen Permeation through Porous Stainless Steel for Palladium based Composite Porous Membranes

Nayebossadri S

Surface topography and hydrogen permeation properties of Porous Stainless Steel (PSS) substrates for thin–films deposition of Pd–based hydrogen separation membrane were investigated. Hydrogen permeance through the as–received PSS substrates demonstrated a wide range, despite a similar average surface pore size of 15 micron determined by SEM and confocal laser microscopy analyses. The surface pores of the PSS substrates were modified by impregnation of varying amounts of tungsten (W) powder. Maximum hydrogen flux reduction of only 28% suggested that W has a limited effect on the hydrogen permeation through the PSS substrate. Therefore, it is suggested that hydrogen transport through PSS substrates is mainly controlled by the substrate geometrical factors, particularly the ratio of the porosity to tortuosity (ε τ ). The variation in the permeance between the nominally similar PSS substrates indicates the importance to independently assess the hydrogen transport characteristics of each of the components in a composite membrane.