Metallic porous supports and ceramic interface layer development for H 2 separation membranes

Hydrogen separation membranes are typically composed of three components: the porous support (ceramic or metallic, as studied in the present work), the porous ceramic interface layer and the hydrogen selective dense layer (usually Pd or a Pd based alloy). The development of a good support and an appropriate ceramic interface layer is a key issue in the high performance membrane manufacturing process. Metallic supports specifically developed for this application have yet to be developed; those used have different features and are manufactured for applications such as filtering devices. There is a clear need to develop porous supports for hydrogen separation membranes that have good surface quality (roughness and pore size) to allow the deposition of a thin selective layer (typically of Pd). In addition, the development of the ceramic layer is of importance, to allow the deposition of a Pd continuous layer of minimum thickness to increase hydrogen permeation and decrease manufacturing costs by minimising use of expensive Pd. The development and characterisation of a thin Pd–Ag membrane deposited by PVD on a composite metallic–ceramic porous support is reported. The surface properties of AISI 316L and nickel supports were improved and the interdiffusion of Pd and Ag was avoided by deposition of an yttria stabilised zirconia (YSZ) layer by dip coating of nanosized YSZ powders.