Kinetic study on the promotion of CO2 absorption in aqueous N-methyldiethanolamine by amino-functionalized ionic liquids

N-methyldiethanolamine (MDEA) is a commercial amine with the deficiency of slow CO 2 absorption rate. In this study, four amino-functionalized ionic liquids (AFILs), i.e., tetraethylenepentamine dimethylimidazole, pentaethylenehexamine dimethylimidazole ([TMTD][2-MI]), tetraethylenepentamine piperazine, and pentaethylenehexamine piperazine, are synthesized to promote CO 2 absorption rate in aqueous MDEA. The result shown that CO 2 absorption rate in 20 wt% aqueous MDEA-10 wt% [TMTD][2-MI] was 10.7 times than that of 30 wt% aqueous MDEA, demonstrating the highest CO 2 absorption rate intensification in aqueous MDEA reported so far. Furthermore, the mechanism underlying the intensified CO 2 absorption rate was elucidated through pH measurement and nuclear magnetic resonance. The comprehensive ability of CO 2 absorption and deprotonation of [TMTD][2-MI] was the dominant factor for the excellent CO 2 absorption rate intensification.