Moisture-Responsive Hydrogel Impregnated in Porous Polymer Foam as CO2 Adsorbent in High-Humidity Flue Gas

This work focuses on developing the adsorbent for carbon dioxide (CO2) capture from high-humidity flue gas by loading moisture-responsive polyethylenimine (PEI) hydrogel interface layer in porous polymer matrix. The chemical structure and porous morphology of the porous adsorbents are characterized. The CO2 adsorption capacity and adsorption thermodynamics are studied. Also, the factors that affect the adsorption capacity including different molecular weight of PEI, loading weight and cross-linking degree of hydrogel, and moisture are investigated. The experimental results show that the porous polymer coated with PEI hydrogel exhibits a much higher adsorption capacity for CO2 and keep a high CO2–N2 selectivity by effective utilization of moisture. The CO2 adsorption capacity as high as 4.85 mmol CO2/g of adsorbent is obtained at 40 °C, with 1,4-butanediol diacrylate (BDA)/PEI ratio of 0.25. Moreover, the formation of three-dimensional cross-linked network in hydrogel shows good regeneration stability.