Thermally stable membranes based on PdNiAu systems with high nickel content for hydrogen separation

Abstract

PdNiAu-based composite membranes were obtained through sequential electroless deposition, varying their composition by modifying the Ni deposition time. After annealing at high temperature, a single phase with FCC structure was obtained in all the membranes, showing homogeneous alloy composition. A decrease in the lattice parameter was evident as the Ni content increased in the alloy. The permselective properties of the membranes were evaluated at different temperatures and pressures. The results showed that H2 permeance decreased as the Ni composition increased in the film and increased as the lattice parameter increased. The best performance was obtained with the membrane containing 29 at.% Ni (11.40 × 10−4 mol m−2 s−1 Pa−0.5), even higher than that reported for pure Pd. The membrane with higher Ni content (54 at.%) and lower permeance (0.20 × 10−4 mol m−2 s−1 Pa−0.5 at 723 K) overcame the performance of some Ni-containing membranes previously reported. The membranes showed high stability for several days at high temperatures.