High-flux H2 separation membranes from (Pd/Au)n nanolayers

A novel strategy for the preparation of supported PdAu alloy layers allows the facile and fast fabrication of highly permeable and selective H₂ separation membranes from refractory metals via electroless plating and low-temperature alloying. Homogenous alloying of multiple, separately deposited Pd and Au layers with thickness in the nm range required less than one week at 773 K under atmospheric H₂ as evidenced by X-ray diffraction and H₂ permeation measurements. The H₂ permeation rate JH₂ became stable within a day even, reaching 0.62 mol m⁻² s⁻¹ at 773 K and ΔPH₂ = 100 kPa. The corresponding N₂ leak rate remained constant during a 350 h experiment, resulting in an ideal H₂/N₂ selectivity of 1400 and demonstrating that such membranes tolerate extended operation at that temperature well.