Kinetics and Mechanism of Chemical Reaction of CO_2 and Ba_2Fe_2O_5 Under Various CO_2 Partial Pressures

摘要

The reaction kinetics of the CO_2 absorption by Ba_2Fe_2O_5, which shows a reversible reaction with CO_2 represented as Ba_2Fe_2O_5 + CO_2 ? BaCO_3 + BaFe_2O_4, was investigated by thermogravimetry under various CO_2 partial pressures [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 the CO_2 absorption mechanism of Ba_2Fe_2O_5 is 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, showing that the activation enthalpy was about 1.6 × 10~2 kJ/mol.