Permeation improvement of LCCF hollow fiber membranes by spinning and sintering optimization

The effects of grain size and wall thickness on the oxygen transport mechanism of (La_0.6Ca_0.4)(Co_0.8Fe_0.2)O_3-δ hollow fiber membranes were investigated. For this purpose, hollow fiber membranes of different geometry were prepared with different spinnerets via phase inversion spinning and subsequently sintered at different temperatures. The influence of the manufacturing conditions on the LCCF microstructure were analysed by SEM, XRD and TEM. With increasing sintering temperature, the grain size increased from 0.4 µm² at 1070 °C to 19.5 µm² at 1245 °C. With bigger grain sizes and lower wall thickness, the oxygen flux shows an increase up to 6.2 ml min⁻¹ cm⁻² (at 1000 °C) in a 50% CO₂ atmosphere. This finding implies that the grain boundaries act as oxygen diffusion barriers.