Fabrication and characterization of Pd/Nb40Ti30Ni30/Pd/porous nickel support composite membrane for hydrogen separation and purification

A porous nickel support was successfully prepared by uniaxial compression of nickel powders. Microstructures and mechanical properties of Nb40Ti30Ni30 membranes fabricated by magnetron sputtering were investigated. Deposited and annealed Nb40Ti30Ni30 membranes consisted of amorphous and crystalline phases, respectively. Higher base temperature was shown to increase the hardness and elastic modulus of the Nb40Ti30Ni30 membrane. Pd/Nb40Ti30Ni30/Pd/porous nickel support composite membranes were then fabricated using a multilayer magnetron sputtering method. The hydrogen permeability of the composite membranes with amorphous and crystallized Nb40Ti30Ni30 metal layer was measured and compared with that of self-supported Nb40Ti30Ni30 and Pd alloys. Solid-state diffusion was shown to be the rate-controlling factor when the thickness of the Nb40Ti30Ni30 layer was about 12 μm or greater, while other factors were in effect for thinner layers (such as 6 μm). The Pd/Nb40Ti30Ni30/Pd/porous nickel support composite membrane exhibited excellent permeation capability and satisfactory mechanical properties. It is a promising new permeation membrane that could replace Pd and PdAg alloys for hydrogen separation and purification.