CO2-tolerant oxygen separation membranes targeting CO2 capture application

Burning fossil fuels with O2/CO2 mixture produces a concentrated CO2 stream and thus enables efficient CO2 capture. In an attempt to improve the economic competiveness of this oxy-fuel combustion technology, intensive efforts have been made to develop ceramic oxygen separation membranes that have a potential to reduce the oxygen production costs over the present cryogenic air separation process. In this paper it is proposed that the O2/CO2 mixture could be supplied by using CO2 as sweeping gas to remove the oxygen separated from air by an oxygen selective membrane. State-of-the-art membranes with the perovskite structure, such as SrCo0.8Fe0.2O3−δ (SCF), suffer degradation upon exposure to the acidic gas CO2. This paper reports that the stability of SCF in CO2 can be improved remarkably by reducing its surface basicity through the introduction of Ti ions, while the oxygen permeability is largely retained. The membrane-based O2/CO2 production concept is also verified with a CO2-tolerant membrane tube.