Simultaneously enhanced permeability and stability in Al doped Pr0.6Sr0.4FeO3-δ oxygen transport membrane for CO2 capture

Abstract

The oxy-fuel combustion technology combined with oxygen transport membrane (OTM) shows a promising future for CO2 capture. Considering the crucial roles of oxygen permeability and stability of OTM, a modified strategy is urgent to develop to promote the oxygen permeation flux and stable structure of membranes under CO2 atmosphere. In this work, we discover that the high oxygen permeability and stability of Pr0.6Sr0.4Fe1-xAlxO3-δ (PSFAl) OTM can be obtained simultaneously by doping the appropriate amount of Al ions. The phase transition temperature is reduced and metal-oxygen average binding energy is increased with Al doping, which improves the structural stability. The oxygen vacancy concentration and oxygen release ability are increased by the Al doping from 0.05 to 0.15, and PSFAl0.1 shows the highest non-stoichiometry at 900 °C. The introduction of moderate Al3+ can accelerate the charge transfer and oxygen ions migration processes during the oxygen permeation reaction. And PSFAl0.1 reaches the highest oxygen permeation flux, which was improved by 20% and 17% in comparison with PSF at 900 °C under He or CO2 atmosphere, respectively. These results provide a helpful strategy to design high oxygen permeability and stability perovskite OTM for CO2 capture.