Patent ID: 7449052

Claim:
Improved composite membrane structure selectively permeable to hydrogen constituted by a continuous filtering film measuring several microns thick and made of palladium or a palladium-based alloy deposited on a rigid porous refractory substrate connected to a pipe for collecting the extracted hydrogen, wherein: said substrate is a permeable sintered metallic body provided with good mechanical resistance or open pores measuring between several microns and about ten microns; a thin metallic film known as the intermediate film with a thickness of between twenty and fifty microns and containing open pores smaller than one micron is deposited on the body of the substrate; the body of the substrate and said intermediate film are made of a metal or alloy having within the range of use temperatures and pressures of the structure, heat expansion coefficients in the presence of hydrogen which are both compatible with those of palladium; the material constituting said intermediate film has within said range a satisfactory chemical stability with regard to the filtering film and said body of the substrate.