Perovskite hollow fiber membranes supported in a porous and catalytically active perovskite matrix for air separation

Abstract

Mixed conducting perovskite membranes have attracted much research interest for use in air separation. However, the application of perovskite hollow fiber membranes is limited by their brittleness. Herein, the fiber bundling in a perovskite matrix is reported to overcome the physical weakness of the individual perovskite hollow fiber membranes. This has been achieved by binding these hollow fibers into one matrix using a porous binder made from the same membrane material, i.e., La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃−δ (LSCF) perovskite. The bending force for one individual LSCF hollow fiber is 2.18 N for a fixed length of 4 cm; in contrast, the bending forces for the LSCF bundle in the same length including 3, 5, 8, and 10 single LSCF hollow fibers are 6.80, 11.77, 23.97, and 39.02 N, respectively. The membrane bundle was evaluated for air separation using a sweep gas mode by passing the air in the shell side and argon through the fiber lumen operated from 800 to 1000 °C. The oxygen flux through the single LSCF hollow fiber at 950 °C was 0.26 mL cm⁻² min⁻¹ (standard conditions) but the bundle gave a higher flux improved by 76% up to 0.46 mL cm⁻² min⁻¹ under similar testing conditions due to the porous matrix with enhanced surface reaction kinetics. The resultant membrane bundle demonstrates exceeding performance for air separation in terms of high oxygen flux, mechanical strength, and thermal stability for an easy scale-up.