Design of Hyperbranched Amine Polymer-Functionalized PolyHIPEs for Rapid CO2 Capture and Separation

A novel solid amine adsorbent meso-PDVB@HBPE-x was prepared by impregnating and cross-linking the hyperbranched amine polymer (HBP-NH2) in a mesoporous polydivinylbenzene (meso-PDVB) substrate with an open-cell structure. The optimum preparation conditions were investigated in detail, and the CO2 adsorption performance of prepared adsorbents was conducted by a fixed bed dynamic adsorption system. It is suggested that beneficial from the low viscosity, the intramolecular cavity of HBP-NH2, and the open-cell structure of meso-PDVB, the best adsorbent meso-PDVB@HBPE-8, which was slightly cross-linked with ethylene glycol diglycidyl ether (EGDE), exhibited a high CO2 adsorption capacity of 5.64 mmol/g under 25 °C and wet conditions and quick adsorption kinetics (a high Qb/Qe ratio of 0.92). Compared with the low-molecular-weight amine tetraethylene pentaamine, HBP-NH2 processes a higher molecular weight and is easily modified. Through cross-linking with EGDE, the N content and CO2 adsorption capacity of meso-PDVB@HBPE-8 remained stable during 20 absorption (at 25 °C)–desorption (at 90 °C) cycles under wet conditions, showing great regeneration stability. The adsorbents showed great potential in CO2/CH4 separation, achieving a CH4 productivity of 18.86 mmol/g from a 15 mL of CO2/CH4 (20:80, v:v) mixed gas. The strategy of synergistically designing the amine and substrate porous structures demonstrates its advantage in the practical application of CO2 adsorption and separation.