Externally self-supported metallic nickel hollow fiber membranes for hydrogen separation

Highly-asymmetric metallic Ni hollow fiber membranes (NHFMs) with a dense inner skin layer and an outer porous substrate were fabricated by a modified phase inversion and sintering technique. A triple-orifice spinneret was used for spinning the hollow fiber precursors with water as the internal coagulant and a solvent-ethanol mixture as the temporary external coagulant. The hollow fiber precursors were sintered in a H2-containing atmosphere at 1100–1400 °C to form dense metallic membranes. Effects of the external coagulant composition and air gap length as well as the sintering temperatures on the morphology of the resultant hollow fiber membranes were systematically investigated. Results indicate that the hollow fiber with an optimal microstructure has achieved a maximum hydrogen flux of 73.17 mmol m−2 s−1 (9.83 mL cm−2 min−1) at 1000 °C, which is about 8 times higher than that obtained from the traditional hollow fiber membrane.