Perovskite oxide absorbents for oxygen separation

The fixed‐bed oxygen absorption processes of the series of Ba 1−x Sr x Co 0.8 Fe 0.2 O 3−δ oxides were studied by oxygen partial pressure swing absorption in the temperature range of 300–850°C. The results show that SrCo 0.8 Fe 0.2 O 3−δ , with the smallest A‐site ion radius, has the largest oxygen absorption capacity (0.402 mmol/g) at 500°C. The oxygen absorption and desorption kinetics fit well with the pseudo‐second‐order kinetics model. Comparing the modeling absorption rate coefficient k 2 with the desorption rate coefficient k 2 ′, all the oxides studied had higher oxygen absorption rates than oxygen desorption ones. In addition, the combined results of X‐ray diffraction analysis, O 2 ‐TPD, room temperature iodometric titration, and thermogravimetric analysis explained the relationship between the oxygen absorption capacities and the average radii of the A‐site ions for this series of Ba 1−x Sr x Co 0.8 Fe 0.2 O 3−δ in the temperature range of 300–600°C. © 2009 American Institute of Chemical Engineers AIChE J, 2009