Preparation of High Stability Pd/Ceramic/Ti-Al Alloy Composite Membranes by Electroless Plating

High stability Pd/ceramic/Ti-Al alloy composite membranes were prepared by electroless plating. Ceramic membranes fabricated by an in situ oxidation method were used as an inter-diffusion barrier between the Pd layer and the Ti-Al alloy support of the membranes to prevent intermetallic diffusion. The stabilities of the ceramic membranes at high temperatures in an H₂ atmosphere were investigated. The permeation performances and stabilities of the Pd/ceramic/Ti-Al alloy composite membranes were also studied. The results showed that the thickness, pore size, and microstructure of the ceramic membranes did not change significantly after the treatment in an H₂ atmosphere at high temperatures, indicating that the ceramic membranes prepared by the in situ oxidation method were stable in an H₂ atmosphere at high temperatures. The thickness of the Pd layer was ~13 μm. The hydrogen permeability and H₂/N₂ selectivity of the Pd composite membranes at 773 K were 2.13 × 10^-3 mol m^-2 s^-1 Pa^-0.5 and 600, respectively. In addition, the H₂ flux, N₂ flux, and H₂/N₂ selectivity of the composite membranes remained nearly constant over three heat cycles (under the same conditions), indicating that the structures of the Pd/ceramic/Ti-Al alloy composite membranes were stable.