Feasibility of CO₂ Capture from O₂-Containing Flue Gas Using a Poly(ethylenimine)-Functionalized Sorbent: Oxidative Stability in Long-Term Operation

Amine-functionalized sorbents are investigated widely for CO2 capture from flue gas, to mitigate the crisis of global CO2 emission, with the advantages of excellent adsorption and regeneration performance. However, the presence of O2 in flue gas (3–10%) would induce the degradation of the sorbents, and some previous works proposed the strategies at the sacrifice of partial CO2 adsorption capacity. Herein, we focused on the oxidation behavior of PEI-functionalized silica in the long-term operation and analyzed the degradation mechanism by characterizing the oxidized sorbents. The sorbent proved to be oxidative stable under a lower temperature of air exposure, but the oxidative degradation would indeed occur at more harsh temperatures (above 90 °C). This study demonstrated that CO2 capture from O2-containing flue gas was feasible by controlling the operating temperature (below 75 °C), and the effective capacity of above 135 mg/g could be maintained in the cyclic CO2 capture.