Hydrogen permeation in palladium-based membranes in the presence of carbon monoxide

A theoretical model is proposed to describe hydrogen permeation in palladium and silver-palladium membranes in presence of a non-inert gas as CO, it is known indeed that hydrogen flux through palladium-based membranes drastically decreases when H-2 is fed in mixtures containing carbon monoxide due to the interaction of the latter gas with the membrane surface. To model this process, the adsorption step of the well-known approach suggested by Ward and Dao has been suitably modified, since it must be considered as a competitive adsorption of the different non-inert molecules on the metal interface. In particular, the competitive adsorption of CO and H-2 has been examined accounting for the spectrum of information available for CO adsorption on palladium, as well as for hydrogen in palladium and palladium-silver alloys. A validation of the model proposed has been performed through a comparison between several literature data and model calculations, over a rather broad range of operating conditions. A quire good agreement was obtained in the different cases, the model, thus, can be profitably used for predictive purposes (C) 2010 Elsevier B V. All rights reserved.