(448e) Perovskite Oxygen Sorbents for “Low Temperature” Thermochemical Air Separation: Correlating Compositions with Redox Performance
- Conference: AIChE Annual Meeting
- Year: 2019
- Proceeding: 2019 AIChE Annual Meeting
- Group: Topical Conference: Innovations of Green Process Engineering for Sustainable Energy and Environment
Wednesday, November 13, 2019 - 9:24am-9:45am
In this study, we systematically investigated the effects of A and B site dopants on the oxygen uptake/release properties of SrFeO3 family of perovskites as oxygen sorbents. Addition of dopants to the A site, namely Ba and La, or the B site, Cu or Mn, increased the oxygen capacity for temperature and pressure swings when compared to undoped SrFeO3. Based on these results, the Mn sample underwent 1000 redox cycles where the sorbent was subjected to oxygen partial pressure swings between 20% O2 and inert at 600 Â°C. The Mn doped sample proved to be stable in terms of oxygen storage capacity, with less than a 3% decrease in capacity. The redox kinetics were similar for the last few cycles when compared to the first few cycles. DFT calculations, in conjunction with the experimental results, indicated that oxygen vacancy formation energies are correlated to initial decomposition temperature for the samples investigated. However, the oxygen storage capacities of the doped samples did not show good correlation with the vacancy formation energies. It was further determined that the dynamic nature of the redox process makes it difficult to use a single vacancy formation energy as the descriptor for the oxygen storage capacities of the sorbents. Instead, a systematic approach was developed to correlate the oxygen storage capacities with the sorbentsâ compositional properties and vacancy formation energies. The findings from this study can potentially be used to develop improved sorbents for thermochemical air separation.