Feasibility of CO₂ Capture from O₂-Containing Flue Gas Using a Poly(ethylenimine)-Functionalized Sorbent: Oxidative...

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.