CO2 absorption properties and microstructure of the perovskite (Sr,Ca)(Fe, Co)O3-δ with different compositions were characterized by TGA, XRD, FT-IR and Mössbauer spectroscopy (TMS and EMS). (Sr0.5Ca0.5)(Fe0.5Co0.5) O3-δ showed the highest absorption of CO2 in the temperature range of 550°C to 850°C in the series of (Sr,Ca)(Fe, Co)O3-δ. In the Mössbauer spectra of the oxides after CO2 absorption, a new sextet of FeIII spinel compounds appeared in addition to two broad sextets of FeIII species at octahedral and tetrahedral sites of brownmillerite structured CaFeO2.5. It is found directly by EMS that Co atoms in the oxides prefer the tetrahedral sites as +3 valence state. The oxides with high activity of CO2 absorption showed an intense vibration band in the FT-IR spectra. These results suggested that the zigzag structure of the mixed oxides is helpful for understanding the rapid absorption of CO2.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics
- Condensed Matter Physics
- Physical and Theoretical Chemistry