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.