Preparation and characterization of dual-layer hollow fibre catalyst membrane for oxygen transport

Asymmetric pore configuration of dual-layer hollow fibre catalyst membrane of NiO-YSZ (inner layer)/La_0.7Sr_0.3Co_0.2Fe_0.8O_3-δ-YSZ (outer layer) has been studied from its morphology and oxygen transport point of view. The membrane was synthesized by phase inversion method and co-extruded using water as the external coagulant and water, ethanol and NMP mixture as the internal coagulant (bore liquid mixture), followed by sintering at 1300 °C for 8h. Volume ratio of water:ethanol:NMP was 4:1:5. The resulted dual-layer membrane has non-sandwich like pore configuration. SEM images of the membrane showed finger-like pores on the internal side and sponge-like pores on the external side. Bending strength of the membrane was 9.76 MPa and nitrogen permeability (gas tightness) was 1.36 x 10⁻⁴ mol.m⁻².s⁻². Pa⁻¹. The oxygen permeability of the membrane at 600, 700 and 800 °C was 2.78 x 10^-8, 2.84 x 10⁻⁸ and 3.10 x 10^-8 mol.s⁻¹.cm^-2, respectively, which is about two order of magnitude lower than oxygen permeability of other reported perovskite-based membranes.