Rational Fabrication of Polyethylenimine-Linked Microbeads for Selective CO₂ Capture

A series of polyethylenimine (PEI)-linked microporous organic polymers were obtained using glycidyl methacrylate-polyethylenimine monomer (GMA-PEI) and different cross-linking agents. Because of well-defined micropores and CO₂-philic plentiful secondary amines, porous organic polymers (POPs) demonstrate high CO₂ uptake and excellent selectivity over other permanent gases, such as CH₄ and N₂. The adsorption capacity of POPs reaches 92 mg g^-1 at 273 K and 1 bar, which is higher than that of recently reported polymers supported on various porous materials such as MCM-41 (33 mg g^-1), alumina (50 mg g^-1), and SBA-15 (60 mg g^-1) under the analogous conditions. The high CO₂/N₂ and CO₂/CH₄ selectivity is observed and reaches 308 and 39, respectively. It is noteworthy that POPs can be entirely regenerated under mild conditions and no loss in activity is detected after four cycles. Notably, no side product is obtained during the fabrication of POPs. Thus, good adsorption capacity, high selectivity, and energy-saving regeneration of POPs make their use in selective CO₂ capture from flue gas and natural gas promising.