Fabrication and operational considerations of hydrogen permeable Mo₂C/V metal membranes and improvement with application of Pd

Mo₂C has previously been demonstrated as an effective catalyst layer to enable stable H₂ permeation through vanadium foils at high temperatures. In this study, this approach was extended to several group V metal foils (V, Nb, and Ta) as well as mixed gas testing. The best permeability was achieved with V, and an activation process was developed to recover the performance of V foils displaying evidence of oxidation. Nb foils yielded ~ 20% the permeability of V, while Ta was too brittle to operate effectively. Mo₂C/V membranes were operated at feed conditions well above the ductile-to-brittle transition pressure without embrittlement; however, the H₂ permeability of Mo₂C/V membranes was significantly attenuated at lower temperatures (< 600 °C). H₂ permeation was also severely inhibited by the presence of N₂ or CO₂ in mixed gas environments due to strong competitive adsorption. The addition of a Pd catalyst layer on top of Mo₂C improved mixed gas stability and increased H₂ permeability to 2 × 10⁻⁸ mol m⁻¹ s⁻¹ Pa^−0.5 at 500 °C for V based membranes. As an interlayer, Mo₂C was demonstrated to be a stable barrier preventing Pd-V interdiffusion at 500 °C while simultaneously allowing significant H₂ permeation.