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

Abstract

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.