Influence of external mass transfer and support resistances for hydrogen permeation through composite palladium membranes

Abstract

Palladium membranes represent a suitable alternative to obtain high purity hydrogen for industrial applications. The modeling of hydrogen permeation through composite membranes is important to understand gas separation systems. Here, experimental and calculated hydrogen flux data through composite palladium/alumina membranes were compared. A dense palladium film of 2.4 μm thick was deposited on a porous support and the produced composite membrane presented infinite hydrogen/nitrogen selectivity. Experimental molecular hydrogen flux at 100 kPa and 723 K was 0.1015 ± 0.0009 mol m−2 s−1. Calculated molecular hydrogen fluxes with the conventional permeation model, without considering external mass transfer and support resistances, were at least 5.7 times greater than experimental data. However, calculated hydrogen flux was only 6.7% lower than the experimental flux at 100 kPa and 723 K when external mass transfer and support resistances were included in the conventional permeation model. Thus, external mass transfer resistances and the permeation through the porous support should be considered for a suitable description of hydrogen fluxes through composite palladium membranes.