Pd and Pd–Ni alloy composite membranes fabricated by electroless plating method on capillary α-Al2O3 substrates

• Porous capillary α-Al2O3 as substrates for the Pd-based membranes preparation.
• Pd and Pd–Ni alloy membranes fabricated by the facile electroless plating method.
• Pd and Pd–Ni membranes showed good stability and hydrogen permeance/selectivity.

Novel home-made porous capillary α-Al2O3 substrates were used as mechanical supports for the Pd-based composite membranes for hydrogen permeation. The rough surface of the substrates with large open pores were modified by vacuum sol–gel dip-coating followed by high temperature calcination treatment. After the introduction of the electroless plating catalysts of Pd particles on the modified surface by an improved catalyzing process, the defect-free Pd and Pd–Ni alloy thin membranes were deposited by cost-effective and facile electroless plating technique. The Pd composite membranes showed a hydrogen permeance of 2.55 × 10−3 mol/(s m2 Pa0.5) at 500 °C, and 730 for the permselectivity of H2/N2. The Pd–Ni alloy composite membranes showed a hydrogen permeance of 2.74 × 10−3 mol/(s m2 Pa0.5), and 640 for the permselectivity of H2/N2 at the same temperature. The Pd and Pd–Ni membranes showed good long-term permeation stability at 500 °C under hydrogen permeation condition. Moreover, the Pd–Ni alloy composite membrane showed a better hydrogen permeation stability of more than 100 h at 300 °C under hydrogen permeation condition without obvious hydrogen embrittlement occurred.