High-Temperature Stability of Palladium Membranes on Porous Metal Supports with Different Intermediate Layers

The effectiveness of intermediate layer to prevent intermetallic diffusion is a key factor for application of Pd membranes on porous stainless steel (PSS) support. In this work, electroless-plated Pd membranes were prepared on PSS disks with two different intermediate layers: in situ oxidized metal oxide and sol-gel derived mesoporous yttria stabilized zirconia (YSZ). A thinner, gastight Pd layer can be formed on PSS support with the YSZ intermediate layer, resulting in a higher hydrogen permeance than Pd membranes on PSS support with the in situ oxidized metal oxide intermediate layer. High temperature permeation and 100-h stability tests showed that both intermediate layers were effective as the diffusion barrier for Pd membranes on PSS supports in the temperature range of 773-873 K. At temperatures above 873 K, only the YSZ intermediate layer is effective in preventing intermetallic diffusion and gives a stable Pd membrane. At the elevated temperatures Pd membranes on PSS support with in situ oxidation layer suffer from a chemical and mechanical stability problem due to reduction of metal oxides in hydrogen atmosphere which, results in intermetallic diffusion and possibly weakens the adhesion of the Pd layer on PSS support.