Composite palladium membranes with improved durability toward hydrogen embrittlement

Palladium membranes have advantages of high hydrogen flux and exclusive permselectivity for hydrogen due to the unique permeation mechanism. Pure palladium membranes are often damaged by hydrogen embrittlement which causes a fatal fracture of membrane particularly due to a-ß phase transition of the palladium hydride at below the critical temperature (293°C). In order to improve the membrane durability against hydrogen embrittlement at repeated thermal cycling we have attempted the following approaches; 1) Alloying of palladium with silver, 2) Control of the palladium particles as nanometer size by confining palladium particles into the nanometer space of microporous support. For these purposes, we proposed here the fabrication of the palladium-silver alloy membranes and the "pore-fill" type palladium membranes based on an electroless plating process.