CO2 absorption performance of ChCl-MEA deep eutectic solvent in microchannel

Deep eutectic solvent (DES) has been a new type of absorbent for CO2 capture due to the advantages of environmental friendliness, simple synthesis and excellent selectivity. A series of choline chloride (ChCl)-monoethanolamine (MEA) deep eutectic solvents with various water contents were prepared. The effects of gas-liquid flow rate, molar ratio of ChCl-MEA, water content and temperature on CO2 absorption performance and mass transfer were investigated. The addition of an appropriate amount of water can effectively reduce the viscosity of DES and improve its CO2 capture ability. The results show that the CO2 absorption efficiency, absorption rate, loading and mass transfer coefficient of ChCl-MEA deep eutectic solvent are optimal when the water content is 70 wt% for the DES with the molar ratio of ChCl and MEA 1:6. When the water content exceeds 70 wt%, the hydrogen bond network of DES would be destroyed, and its CO2 capture ability would be weakened. According to the Arrhenius equation, the reaction activation energy of CO2 absorption is as low as 7.54 kJ·mol−1 when the water content is 70 wt% in DES with the molar ratio of ChCl and MEA 1:6. This study can provide technical support for the application of deep eutectic solvents in CO2 capture.