Highly stable dual-phase Ce0.9Pr0.1O2-δ-Pr0.6Sr0.4Fe1-xTixO3-δ oxygen transport membranes

Abstract

Mixed ionic-electronic conducting (MIEC) oxygen transport membranes (OTMs) could be used for high-temperature oxygen separation, solid oxide fuel cells (SOFC), and membrane reactors. However, many high-performance OTM materials are chemically unstable in high-temperature CO2 and reducing atmospheres. Here, we proposed a series of 60 wt%Ce0.9Pr0.1O2-δ-40 wt%Pr0.6Sr0.4Fe1-xTixO3-δ (CPO-PSFTxO, x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1) OTMs through Ti doping in Fe-based dual-phase membranes. A small amount of Ti doping increased the oxygen vacancy concentration and simultaneously enhanced the structural stability at high temperatures. The optimal CPO-PSFT0.1O membrane could maintain oxygen permeation fluxes of 0.512 mL min−1 cm−2 and 0.306 mL min−1 cm−2 over 150 h under He and CO2 sweeping at 1000 °C. Furthermore, co-doping with Cu improved oxygen permeability by more than 50 % while maintaining performance stability. Simultaneously, CPO-PSFT0.1O had excellent CO2 resistance and could maintain structural stability in 5 % H2/Ar at 800 °C. This material has potential applications in constructing membrane reactors containing reducing atmospheres and high-temperature SOFC.