Palladium–lead alloys for the purification of hydrogen-containing gas mixtures and the separation of hydrogen from them

Abstract

Ingots of palladium alloys with 5, 8, 12, 16, and 20 wt % Pb, which correspond to the Pd-based solid solution region, are prepared by arc melting in a protective atmosphere. Foils 50 μm thick are prepared from the ingots subjected to cold rolling and intermediate vacuum annealing. The membrane characteristics of the foils, which include the strength, the hydrogen permeability, the corrosion resistance, the α ⇄ β hydride transition temperature, and the crystal lattice parameters, have been studied. The Pd–8 wt % Pb alloy is shown to exhibit the maximum specific hydrogen permeability (2.6 N m³ mm/(m² h MPa^0.5)) at 500°C, an adequate plasticity (δ = 12%), a high strength (${\sigma _{{u_{hard}}}}$ = 550 MPa, ${\sigma _{{u_{ann}}}}$ = 230 MPa), and corrosion resistance against one of the hydrocarbon-conversion products (CO₂), which allow us to recommend this alloy for application as the membranes in filtration membrane elements.