Palladium surface modified La0.6Sr0.4Co0.2Fe0.8O3−δ hollow fibres for oxygen separation

La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) hollow fibres were prepared by a phase inversion/sintering method using polyetherimide as a binder. In order to overcome surface exchange kinetics limitation, LSCF hollow fibres were coated with ∼200 nm palladium (Pd) nanoparticles. The O2 flux of best performing membranes increased by up to 350% in comparison to unmodified LSCF hollow fibres. Optimal enhancement was achieved with a single Pd coating. Additional coatings resulted in reduced O2 fluxes, thus counter acting the beneficial spill-over effect of the catalyst. Long term stability testing in atmospheric air at 850 °C showed that a LSCF membrane modified with a single Pd coating continually outperformed a pure LSCF hollow fibre for over 400 h, though the level of enhancement was reduced over time. A dramatic reduction in performance of more than 45% occurred within the first 24 h of testing, which was attributed to the coalescence and aggregation of Pd catalyst particles to ∼1000 nm size at the LSCF grain boundaries. This greatly reduced the available area for the oxygen species to spill-over onto the LSCF surface and thus reduced the overall O2 flux.

► La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) hollow fibres were coated with palladium (Pd) nanoparticles.
► The O2 flux of best performing membranes increased by up to 350% in comparison to unmodified LSCF hollow fibres.
► Optimal performance was achieved with a single Pd coating.
► LSCF Pd outperformed a pure LSCF hollow fibre for over 400 h testing, though O2 fluxes reduced over time.
► Pd particles aggregated at the LSCF grain boundaries within the first 24 h of testing, reducing O2 fluxes by > 45%.