Preparation of highly stable palladium alloy composite membranes for hydrogen separation

Palladium alloy composite membranes for hydrogen separation have been fabricated on a porous stainless steel (SS) support by the vacuum electrodeposition and laminating procedure of thin palladium alloy film less than 25 mm. In spite of the formation of an alloy with copper, the brittleness of the palladium-based membrane due to palladium hydride in the presence of hydrogen diffusing through the membrane was a major problem, which causes a failure of the membrane with formation of pinholes. By preparing the composite membrane without microstructural change, it is possible to obtain both high performance and stable membrane. The permeation behavior for the prepared composite membranes was measured in long-term. During permeation testing, the physical and morphological stability of the composite membranes have been observed and the long-term tests have shown very high performances above 3 months of operation. Furthermore, these composite membranes had the capability to separate hydrogen from gas mixture with complete hydrogen selectivity and can be used to produce ultra-pure hydrogen for applications in membrane reactor and so on.

360°C 380°C 400°C 420°C 440°C PH0.5-PL0.5 Fig. 3. Hydrogen flux for a Pd–Cu alloy composite membranes with 25 mm.