Polyethylenimine-Impregnated Resin for High CO₂ Adsorption: An Efficient Adsorbent for CO₂ Capture from Simulated Flue Gas and Ambient Air

Polyethylenimine (PEI)-impregnated resins with high CO₂ adsorption capacity were successfully prepared in this study. The nonpolar resin HP20 was suitable for PEI loading to achieve high CO₂ adsorption, and the optimal PEI loading was 50 wt %. On the basis of the pore-size distribution of the resin before and after PEI modification, it can be found that mesopores of <43 nm were mainly responsible for PEI loading and pores in the range of 43–68 nm were probably favorable for CO₂ diffusion. The adsorbed amount of CO₂ on HP20/PEI-50 decreased with increasing adsorption temperature because of the dominant role of exothermic reaction of CO₂ adsorption. The adsorption of CO₂ on the adsorbent was very fast, and sorption equilibrium was achieved within 6 min at 75 °C. HP20/PEI-50 almost kept a stable adsorption capacity for CO₂ at concentrations of 15 vol % and 400 ppm in the consecutive adsorption–desorption cycles, and its adsorption capacity was 181 mg/g from pure CO₂ and 99.3 mg/g from 400 ppm CO₂ at 25 °C, higher than all PEI-modified materials reported. The high volume-based amount of CO₂ adsorbed on HP20/PEI-50 (96.0 mg/cm³ at 25 °C and 84.5 mg/cm³ at 75 °C for pure CO₂) is beneficial to reducing the required volume of the adsorption bed for CO₂ capture. This spherical and stable HP20/PEI-50 adsorbent with high and fast CO₂ adsorption exhibits a very promising application in CO₂ capture from flue gas and ambient air