Enhancing oxygen permeation through Fe2NiO4–Ce0.8Tb0.2O2−δ composite membranes using porous layers activated with Pr6O11 nanoparticles

Abstract

Fe₂NiO₄–Ce_0.8Tb_0.2O_2−δ (NFO–CTO) composite membranes are of interest to separate oxygen from air. In this study, we investigate the influence of the catalytic activation of NFO–CTO membranes on the oxygen permeation rate. Specifically, the effect of activating porous NFO–CTO layers –coated on both sides of the dense NFO–CTO membrane – with Pr₆O₁₁ nanoparticles is studied. Measurements in the temperature range 850–700 °C revealed a 2–4 fold increase in the oxygen flux after coating a 30 μm-thick porous NFO–CTO layer on both membrane sides, and a 6–12 fold increase relative to the bare membrane after activating the porous layers coated on both sides of the membrane with Pr₆O₁₁ nanoparticles. No degradation of the oxygen fluxes was found in CO₂-containing atmospheres. Pulse isotopic exchange measurements confirmed an increase in the oxygen surface exchange rate of more than one order of magnitude after dispersion of Pr₆O₁₁ nanoparticles on the surface of NFO–CTO composite powders. Electrochemical impedance spectroscopy measurements on symmetrical cells, using Gd-doped ceria (CGO) as the electrolyte and Pr₆O₁₁-activated NFO–CTO electrodes, showed a 10-fold decrease in the polarization resistance compared to non-infiltrated electrodes in air. Modification of porous layers by activation with Pr₆O₁₁ nanoparticles is considered a viable route to enhance the oxygen fluxes across composite membranes.