Sponge-like polyethyleneimine adsorbents with interconnected open channels enabling ultra-high CO2 adsorption and separation capacity

A novel solid amine adsorbent with interconnect open-cell porous structure was successfully synthesized by crosslinking polyethyleneimine (PEI) with ethylene glycol diglycidyl ether (EGDE) via high internal phase emulsion (HIPE) polymerization. The preparation conditions were optimized. The adsorption performance of the prepared adsorbent for CO2 was evaluated by fixed bed dynamic adsorption experiment. The results indicated that the optimal adsorbent PEI70K-E-HIPE-8 exhibited a record high CO2 adsorption capacity of 14.22 mmol/g, amine efficiency of 83% and ratio of breakthrough capacity to equilibrium capacity of 0.92 (abbreviated as Qb/ Qe ratio). Both adsorption capacity and adsorption kinetics are much better than those of PEI70K-E-gel-8 prepared without using HIPE template. The adsorbent also showed good CO2/CH4 separation performance, a CH4 productivity of 54.84 mmol/g could be obtained while using PEI70K-E-HIPE-8 to separated it from a 20 mL CO2/ CH4 (20:80, v:v) mixed gas, remarkably higher than that of PEI70K-E-gel-8 (0.28 mmol/g). PEI70K-E-HIPE-8 could keep a stable adsorption and separation performance after at lease 15 adsorption-desorption cycles. The superior CO2 adsorption capacity and adsorption kinetics make it a promising candidate in practical CO2 adsorption and CO2/CH4 separation application.