A temperature programmed desorption investigation on the interaction of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) perovskite oxides with CO2 in the absence and presence of H2O and O2

摘要

The adsorption of CO2 on Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSCF) perovskite oxides in the absence and presence of Ct2 and H2O at various temperatures was investigated by temperature programmed desorption (TPD). XRD was used to characterize the phase of the samples before and after adsorption. No CO2 desorption peak was observed when CO2 was adsorbed on BSCF at room temperature. A CO2 desorption peak from the decomposition of surface Sr_(0.6)Ba_(0.4)CO3 appeared after CO2 was adsorbed at 400-700 °C. The reactivity of CO2 with BSCF increased with increasing temperature, and the resulted carbonate became more stable. When CO2 and O2 were co-adsorbed, the CO2 desorption peak shifted to lower temperature and the peak area decreased compared with when only CO2 was adsorbed, which was due to the competitive adsorption of CO2 and O2. The adsorption of CO2 on BSCF was promoted in the presence of H2O. A CO2 desorption peak ranging from ca. 250 to 500 °C, assigned to the decomposition of the bicarbonate, was observed when H2O was added. The amount of CO2 adsorbed on Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) increased when the barium doping level increased from 0.3 to 1.