(573s) Perovskite Oxides As New Family of Tunable CO2 Sorbents

CO₂ adsorption by solid sorbents represents an attractive option for carbon capture due to its potential for low energy consumption, ease of operation, and minimal corrosion or sorbent loss. This study introduces perovskite oxides as a new family of highly tunable solid sorbents. Despite a relatively limited sorption capacity (~up to 0.68 wt.%) which ties to their surface area, perovskite oxides offer remarkable structural and compositional flexibility to tailor their sorption thermodynamics and kinetics. Using Sr_xLa_1-xFeO₃ (x=0, 0.2, 0.5, and 0.7) as a model system, we demonstrated that varying the A-site composition of the perovskite oxide leads to substantial change in the CO₂ adsorption and desorption behavior, allowing a tunable CO₂ release within a temperature range of 180 to 500+℃. A strong correlation between the oxide surface area and sorption capacity was also established. Despite the low surface area inherent to perovskite oxides, we managed to enhance their surface area from 3 to 5 m²/g (prepared by a salt assisted reactive grinding method) to ~30 m²/g using a electrospinning method. Sr_0.2La_0.8FeO₃ prepared via electrospinning exhibited a relatively moderate desorption temperature (~240°C) and a CO₂ sorption capacity of 0.68 wt.%. Based on analysis of the adsorption isotherms, the Sr_0.2La_0.8FeO₃ sorbent adsorbs CO₂ via chemisorption at low pressures (0-1 kPa) and it switches to physisorption at higher CO₂ partial pressures (10-120 kPa). TEM characterizations revealed that perovskite synthesis via the electrospinning method results in the formation of perovskite nanorods, which exhibit high surface area and unique surface properties compared to oxides prepared with conventional methods. This study demonstrates the tunability of perovskite oxides as a new family of CO₂ sorbent materials and the potential to further enhance their surface area towards practical applications in CO₂ capture and utilization.