Electrochemical separation of CO2 from a simulated flue gas with high-temperature ceramic–carbonate membrane: New observations

•Highest CO2 flux density among reported in the literature.•First report on facilitated transport of CO2 and O2 through CeO2–carbonate membrane.•Proposed a new model for the facilitated CO2 and O2 transport.

Development of highly efficient and cost-effective carbon capture and storage technology is vitally important to the reduction of carbon emissions and mitigation of global climate change. In this study, a ceramic–carbonate membrane conducting both oxide-ions and carbonate-ions is explored to directly separate CO2 from a simulated flue gas in the temperature range of 550–650 °C. The CO2 permeation flux density is found to increase with temperature as well as concentrations of CO2 and O2, and stable over a testing period of 100 h. It is also observed for the first time that the membrane is permeable to O2. A parallel mechanism responsible for the facilitated CO2 and O2 transport is proposed.