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The role of A‐site ion nonstoichiometry in the oxygen absorption properties of Sr 1+x Co 0.8 Fe 0.2 O 3 oxides
Author(s) -
He Yufeng,
Zhu Xuefeng,
Yang Weishen
Publication year - 2011
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.12246
Subject(s) - oxygen , desorption , chemistry , absorption (acoustics) , brownmillerite , analytical chemistry (journal) , perovskite (structure) , limiting oxygen concentration , solid oxygen , oxygen storage , inorganic chemistry , crystallography , materials science , adsorption , organic chemistry , chromatography , composite material
Sr 1+x Co 0.8 Fe 0.2 O 3 (−0.2 ≤ x ≤ 0.1) oxides have been synthesized and investigated as potential oxygen absorbents for high temperature oxygen separation processes. It was found that the A‐site ion deficient Sr 0.95 Co 0.8 Fe 0.2 O 3 and Sr 0.9 Co 0.8 Fe 0.2 O 3 oxides have larger oxygen absorption capacities, and slightly higher oxygen desorption rates. However, the A‐site ion excess Sr 1.05 Co 0.8 Fe 0.2 O 3 and Sr 1.1 Co 0.8 Fe 0.2 O 3 exhibited much higher oxygen desorption rates, but smaller oxygen absorption capacities. The oxygen absorption capacities were further verified using oxygen temperature‐programmed desorption technique, and the oxygen desorption rates were well described by a pseudo‐second‐order kinetics model. In addition, the long‐term stability of Sr 0.9 Co 0.8 Fe 0.2 O 3 was investigated for 280 h (1120 loops) with switching between oxygen absorption and desorption. The excellent stability was confirmed by X‐ray diffraction patterns which suggested that the cyclic processes of oxygen absorption and desorption took place between the perovskite structure with disordered oxygen vacancies and the brownmillerite structure with ordered oxygen vacancies. © 2010 American Institute of Chemical Engineers AIChE J, 2011