Modelling and systematic experimental investigation of mass transfer in supported palladium-based membrane separators

Hydrogen separation with palladium-based membranes is considered as a promising technology for pre-combustion CO2 capture as well as for industrial hydrogen production. With improvements in membrane permeance, resistances to mass transfer are becoming increasingly important. In this work, a systematic approach is followed in order to discern and account for different contributions to the overall mass transfer resistance, based on a combined experimental and modelling approach. Experiments have been performed that started with pure H2 feed, without sweep, subsequently followed by introducing N2 on the feed side, and N2 sweep gas. Using a phenomenological description for the palladium layer and the dusty gas model for the membrane support, coupled to a 2D Navier–Stokes solver with a convection-diffusion equation to account for possible concentration polarisation, all relevant mass transfer resistances are adequately modelled. For the conditions investigated, the main resistances to mass transfer are concentration polarisation in the retentate, hydrogen permeation through the metallic palladium layer, and a diffusional resistance in the support layer.

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► Combined modelling and systematic experimental investigation.
► Concentration polarisation, support diffusion significant mass transfer resistances.
► In support, diffusion resistance by sweep gas most important.
► Pressure drop over membrane support negligible.