Perovskite oxide absorbents for oxygen separation

Abstract

AbstractThe fixed‐bed oxygen absorption processes of the series of Ba1−xSrxCo0.8Fe0.2O3−δ oxides were studied by oxygen partial pressure swing absorption in the temperature range of 300–850°C. The results show that SrCo0.8Fe0.2O3−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 k2 with the desorption rate coefficient k2′, all the oxides studied had higher oxygen absorption rates than oxygen desorption ones. In addition, the combined results of X‐ray diffraction analysis, O2‐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 Ba1−xSrxCo0.8Fe0.2O3−δ in the temperature range of 300–600°C. © 2009 American Institute of Chemical Engineers AIChE J, 2009