BaCoO3−δ perovskite-type oxygen carrier for chemical looping air separation, part Ⅰ: Determination of oxygen non-stoichiometry and cyclic stability of oxygen carrier

Oxidation Kinetics of Nanocrystalline Hexagonal RMn1–xTixO3 (R = Ho, Dy)

“…These oxygen transport properties also make perovskite oxides promising material candidates within applications such as solid oxide fuel cells and metal–air batteries. , Generally, bulk transport of oxygen is rate-limiting for particles larger than ∼1 μm, while the catalytic splitting or formation of the O 2 molecule on the surface is rate-limiting for smaller particles . As oxygen vacancies in perovskites have limited mobility, temperatures as high as 600–800 °C are generally required to achieve sufficiently rapid oxygen exchange. , At such elevated temperatures, these materials are prone to degradation and kinetic demixing . The OSC and oxygen exchange kinetics can be improved by doping on the A-site, B-site, or both. , Compared to Sr 0.8 Ca 0.2 FeO 3 and CaMnO 3 , Sr 0.8 Ca 0.2 Fe 0.4 Co 0.6 O 3−δ and Ca 0.8 Sr 0.2 MnO 3 show faster surface oxygen exchange kinetics, shorter times required for oxidation, and smaller activation energy for bulk oxygen diffusion. , Similar kinetics have also been found for SrFeO 3 -based materials , making both material systems good candidates for CLAS at lower temperatures.…”

“… 16 As oxygen vacancies in perovskites have limited mobility, temperatures as high as 600–800 °C are generally required to achieve sufficiently rapid oxygen exchange. 8 , 17 At such elevated temperatures, these materials are prone to degradation and kinetic demixing. 18 The OSC and oxygen exchange kinetics can be improved by doping on the A-site, B-site, or both.…”

BaCoO2 with Tetrahedral Cobalt Coordination: The Missing Element to Understand Energy Storage and Conversion Applications in BaCoO3−δ-Based Materials

“…However, it looks “continuous” from the neutron data in Figure a. Such a property has interesting implications in the reversible oxygen storage/release between these two phases as a continuous behavior without any hysteresis is always targeted to reach high reproducibility for oxygen evolution/reduction reaction applications; Cai et al have recently demonstrated such a scenario by reporting outstanding oxygen carrier capacity with a high stability of hexagonal BCO phases for chemical looping air separation during 50 cycles at 1148 K . The BCO to 12H-BaCoO 2.6 transformation could also explain the reasons for the phase coexistence between these two compounds during BCO synthesis in the literature, as combined TGA-neutron diffraction data were not previously available to estimate the optimum temperature of interest.…”

“…have recently demonstrated such a scenario by reporting outstanding oxygen carrier capacity with a high stability of hexagonal BCO phases for chemical looping air separation during 50 cycles at 1148 K. 52 The BCO to 12H-BaCoO 2.6 transformation could also explain the reasons for the phase coexistence between these two compounds during BCO synthesis in the literature, as combined TGA-neutron diffraction data were not previously available to estimate the optimum temperature of interest. Additional temperature increases resulted in an increase in the BaCoO 2.6 /BaCoO 3−δ phase fraction, which reached 70/30%, respectively, at the highest temperature (1177 K) with continuous oxygen release, Figure S10; at this temperature, the stoichiometry is BaCoO 2.56 .…”

Kinetic and Thermodynamic Enhancement of Low-Temperature Oxygen Release from Strontium Ferrite Perovskites Modified with Ag and CeO2

“…A class of materials of interest is nonstoichiometric perovskite oxides, , with the general formula AB O 3−δ , as they release oxygen at lower temperatures than conventional stoichiometric oxides (e.g., CuO, Fe 2 O 3 ) and with faster kinetics, albeit with lower specific oxygen capacity. − Material screening, using in silico and thermogravimetric methods, has identified strontium ferrite, SrFeO 3−δ , as a suitable candidate material for CLAS, , able to release oxygen in air at a lower T H (400 °C) than most other studied materials. Particles of perovskite OC materials for CLAS can be produced via straightforward solid-state methods from oxide and carbonate precursors , and have demonstrated stable CLAS performance with fast kinetics of oxygen release over up to 1000 redox cycles in air and N 2 .…”