Single phase specimen of polycrystalline Ba
2Fe
2O
5, which has been a candidate for CO
2 absorbents, was prepared by solid state reaction method under N
2 flow. Ba
2Fe
2O
5 showed weight increase above 450 °C under CO
2 flow, which was originated from CO
2 absorption. The weight decrease due to CO
2 desorption was observed above 1100 °C under CO
2 flow. Thermogravimetry (TG) and X-ray diffraction measurements have revealed that Ba
2Fe
2O
5 can reversibly react with CO
2, which is represented as Ba
2Fe
2O
5 + CO
2 ⇄ BaCO
3 + BaFe
2O
4. Thermodynamic calculation of this reaction was carried out, showing agreement with the results obtained by TG measurements. The reaction kinetics of CO
2 absorption by Ba
2Fe
2O
5 was investigated by TG under various
P(CO
2)'s. The calculated Ellingham diagram of the reaction was found to show agreement with the variation in the equilibrium temperature of the reaction with
P(CO
2). The results of the morphology observation, specific surface area analysis and TG measurement suggested that CO
2 absorption mechanism was described by a superficial reaction, a diffusion-controlled process, and a sintering reaction as the reaction proceeds. The kinetics of CO
2 absorption for the diffusion-controlled process has been analyzed with the Jander function.
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