Enhancing oxygen permeation of solid-state reactive sintered Ce0.8Gd0.2O2-δ-FeCo2O4 composite by optimizing the powder preparation method

Abstract

Dual phase membranes with mixed ionic-electronic conductivity exhibit promising properties for applications in pure oxygen separation under harsh atmospheres. The conductivity of an individual phase within dual phase membranes is often attenuated by the blocking effects from the other phase(s). Here, facile but effective ways are reported to alleviate such effects by optimizing the powder preparation method for a solid-state reactive sintering process. Powder mixtures with a nominal composition 85 wt% Ce0.8Gd0.2O2-δ:15 wt% FeCo2O4 were prepared by traditional wet ball milling method, as well as a moderate dry mixing approach. Using a modified wet ball milling procedure, homogenous powder mixtures with fine particle size are obtained and the synthesized membrane shows a fine and homogenous microstructure that realizes high oxygen permeance. Besides, a novel “dual phase” membrane having one ionic conductive monophase zone and one mixed ionic-electronic conductive multiphase zone was sintered using dry-mixed powder mixtures. With individual mesoscale percolations, two phase zones provide relatively straight paths for ionic conduction and electronic conduction, respectively, which contributes to achieving the highest oxygen permeance among all the sintered membranes.