LAUSR

Chemical looping air separation has numerous potential benefits in terms of energy saving and emission reductions. The current study details a combination of density functional theory calculation and experimental efforts to design A and B-site co-doped SrFeO3 perovskites as "low temperature" oxygen sorbents for chemical looping air separation. Substitution of the SrFeO3 host structure with Ca and Co lowers oxygen vacancy formation energy by 0.24-0.46 eV and decreases the oxygen release temperature. As a result, Sr1-xCaxFe1-yCoyO3 (SCFC, x = 0.2, 0.0 < y < 1.0) spontaneously releases oxygen at 400-500 oC even under a relatively high oxygen partial pressure (e.g. PO2 = 0.05 atm). Sr0.8Ca0.2Fe0.4Co0.6O3 exhibits a significantly higher oxygen capacity of 1.2 w.t.% at 400 °C and under a PO2 swing between 0.05 and 0.2 atm, when compared to the <0.2 w.t.% capacity for un-doped a SrFeO3 (SF) and Ca doped Sr0.8Ca0.2FeO3 (SCF). Electrical conductivity relaxation (ECR) study demonstrates co-doping of Ca and Co lowers activation energy of oxygen diffusion and surface oxygen exchange by 26.6 and 137.9 kJ/mol accordingly, resulting in fast redox kinetics of SCFC comparing to SCF perovskite. The SCFC oxygen sorbent also exhibits excellent stability for 2000 redox cycling for air separation.