Metallic porous supports and ceramic interface layer development for H² separation membranes

Hydrogen separation membranes are typically composed of three components: the porous support (either ceramic or metallic which are studied in this work), the porous ceramic interface layer and the hydrogen selective dense layer (mainly Pd or Pd based alloys). The development of a good support and an appropriate ceramic interface layer is a key issue in the high performance membrane manufacturing process. Nowadays there are no metallic supports specifically developed for this application, and the ones used have different features and are manufactured for other applications such as filtering devices. Therefore, there is a clear need of developing porous supports for hydrogen separation membranes. These supports should have a good surface quality (roughness and pore size) to allow a thin selective layer deposition (typically made of Pd). In addition, the development of the ceramic layer is of prime importance because it will allow depositing a Pd continuous layer with a minimum thickness, increasing the hydrogen permeance and decreasing its manufacturing costs due to high price of Pd. In this work the development and characterization 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 interdifussion of Pd and Ag was avoided by deposition of an yttria stabilized zirconia (YSZ) layer by dip coating of nanosized YSZ powders.