  Developing good performance and low-cost oxygen permeable membranes for CO2
capture based on the oxy-fuel concept is greatly desirable but challenging.
Despite tremendous efforts in exploring new CO2-stable dual-phase membranes,
its presence is however still far from meeting the industrial requirements.
Here we report a series of new Ca-containing CO2-resistant oxygen transporting
membranes with composition 60wt.%Ce0.9Ln0.1O2-40wt.%Ln0.6Ca0.4FeO3(CLnO-LnCFO;
Ln = La, Pr, Nd, Sm) synthesized via a Pechini one-pot method. Our results
indicate all investigated compounds are composed of perovskite and fluorite
phases, while the perovskite phases in the CNO-NCFO and CSO-SCFO membranes
after sintering generates Ca-rich and Ca-less two kinds of grains with
different morphologies, where the Ca-less small perovskite grains block the
transport of oxygen ions and eventually result in poor oxygen permeability.
Among our investigated CLnO-LnCFO membranes, CPO-PCFO exhibits the highest
oxygen permeability and excellent CO2 stability, which were mainly associated
with the improvement in crystal symmetry, non-negligible electronic
conductivity of fluorite phase and the enhancement in electronic conductivity
of perovskite. Our results establish Ca-containing oxides as candidate material
platforms for membrane engineering devices that combine CO2 capture and oxygen
separation.
