H2 separation from gas mixtures through palladium membranes on metallic porous supports

Thin-film palladium membranes are one of the most promising technologies for hydrogen separation from gas mixtures, involving advantages, such as a separation efficiency approaching 100%, high permeability, and operating conditions compatible with upstream fuel conversion processes. In this work, palladium films, with thickness between 10 ìm and 40 ìm, were deposited above stainless steel porous tubular supports using a modified electroless plating technique. The application of vacuum during palladium deposition, together with support abrasion and oxidation above 700°C, were demonstrated to be effective in limiting the presence of film defects. The prepared membranes were then tested in an experimental set-up using a wide range of operating conditions (transmembranal pressure 2-20 bar, temperature 300-550°C) in order to evaluate their performances. A hydrogen permeation flow rate of 0.25 mol/m2s, with a selectivity with respect to CO2 as high as 5000, was obtained at 450°C and 10 bar of partial transmembranal pressure. A mathematical model was set in order to interpolate the experimental data and simulate the permeation of hydrogen through palladium. A good agreement between experimental and simulation results was obtained