Physicochemical synergistic adsorption of CO2 by PEI-impregnated hierarchical porous polymers

Abstract

Amine-functionalized porous polymers have been considered as a prominent chemical adsorption material for carbon capture and storage (CCS) process, because of their large adsorption capacity and high selectivity. By comparison, the low energy-consumption for desorption and high recyclability are the advantages of the physical adsorption approach. In this work, an amine-functionalized hierarchical porous polymer was prepared by HIPE (high internal phase emulsions) template and amine impregnation strategy, and applied as CO₂ adsorbent to realize chemical adsorption and physical adsorption simultaneously. First, a hierarchical porous matrix of poly(styrene-glycidyl methacrylate) was prepared by the HIPE method. The formed meso/micropores in the typical porous polymer matrix could attract CO₂ molecules, where the physical adsorption was achieved. Subsequently, PEI (polyethyleneimine) was impregnated into the porous polymer with abundant macropores, and the numerous of amino groups provided the reaction sites, where the chemical adsorption was achieved. As a result, an effective CO₂ adsorption material was obtained via controlling the porous structure by changing the volume fraction of dispersive phase, impregnation condition and amine loading. Aided by the chemical adsorption of amino groups, the CO₂ adsorption capacity of the obtained adsorbent reached 3.029 mmol/g. Moreover, the CO₂ adsorption thermodynamics confirmed the physicochemical synergistic adsorption, and then the Q_st reduced to 31–42 kJ/mol and a good cyclic stability was obtained. As conclusion, the porous adsorbent showed a good industrial application prospect. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.