Study on CO2 absorption by EmimCl-MEA deep eutectic solvent in microchannel

Carbon dioxide (CO2) is widely acknowledged as the primary contributor to the greenhouse effect. Microchannel reactors can be used for enhancing chemical processes, solving the problems of limited gas-liquid mass transfer, and have significant advantages in CO2 capture. In this study, the deep eutectic solvent (DES) prepared by mixing ionic liquid (1-ethyl-3-methylimidazolium chloride, EmimCl) and Ethanolamine (MEA) in a molar ratio of 1:1 was selected for CO2 capture in a microchannel. The structure and physical properties of the DES were investigated, and the effects of gas and liquid flow rates, water content, and CO2 concentration on the CO2 absorption properties were analyzed. The increase of the water content not only significantly reduces the viscosity of DES, but also improves the CO2 absorption performance. In addition, the CO2 absorption mechanism of this DES has been obtained by the NMR spectrum, showing that the absorption process is a rapid chemical absorption process between CO2 and MEA. The Cl- of EmimCl could stabilize the protonated amine and prevent it from further reacting with MEACO2-, furthermore increasing the CO2 absorption rate.