Preparation of thin Pd-based composite membrane on planar metallic substrate: Part II. Preparation of membranes by electroless plating and characterization

The availability of cheap and pure hydrogen is critical for fuel cell infrastructure. Thin and pinhole-free Pd-based membranes could be a significant step in the economical production of pure hydrogen. Thin Pd-based layers can be deposited on a porous substrate with appropriate mechanical strength, but low permeation resistance. Porous stainless steel is advantageous as the substrate for thin Pd-based composite membranes. We previously reported a novel method to coat a ceramic layer as an interdiffusion barrier and surface modifier on commercial porous stainless steel. This paper covers the deposition of Pd films on planar untreated and pre-treated stainless steel substrates as industrial prototypes for scaling-up thin Pd-based composite membranes. A thin (∼5 μm) and pinhole-free Pd composite membrane was successfully achieved with this configuration. Permeation and characterization results of the composite membranes demonstrated the effectiveness of the ceramic layers in preventing interdiffusion and modifying the substrate surface. Hydrogen permeation fluxes up to 95 m3/m2 h were achieved for the composite membrane at 823 K and hydrogen pressure difference of 3.4 bar.