Abstract: A PdAu membrane was prepared by sequential electroless plating of Pd and Au onto the outside surface of porous 冏-Al2O3 substrate followed by annealing and H2/N2 performance evaluation. X-ray diffraction was employed to study the PdAu alloy phase formation at 823 K under H2 and N2 atmospheres. Annealing experiments demonstrated that 200 h was needed to form a stoichiometrically homogeneous, 2-m thick Pd82.63Au17.37 membrane from sequentially deposited layers at 823 K and a noticeable particle agglomeration was observed under N2 atmosphere. The performance of the PdAu alloy membrane was evaluated with respect to the H2 flux and permselectivity between 823 and 423 K, which showed that the PdAu alloy membrane had higher H2 flux and lower activation energy than those of pure Pd membrane. The activation energy in the high temperature range is consistent with bulk diffusion-limited H2 transport, while the changes of these charac-teristics at lower temperatures below 573 K indicate desorption or surface limited H2 flux. After the conclusion of gas studies, the PdAu membrane was broken, the thickness and composition of the PdAu layers were determined by SEM and EDX completely.

Key words: electroless plating, cyanide-free electroless gold plating, palladium-gold composite membrane, palladium-gold alloy, hydrogen permeation