CO2 absorption and desorption performance by ChCl-MEA-PZ deep eutectic solvent aqueous solutions

Abstract

With the increasingly serious climate problem, carbon dioxide capture has been paid more and more attention. Deep eutectic solvent (DES), which is environmentally friendly and simple to synthesize, has attracted considerable attention as a new type of carbon dioxide absorbent. Choline chloride (ChCl) - monoethanolamine (MEA) - piperazine (PZ) DESs were prepared. The chemical reaction between ChCl-MEA-PZ DES and CO2 was confirmed to be the zwitterionic mechanism by NMR spectrum analysis. The influences of molar ratio between ChCl, MEA and PZ, gas–liquid flow rates, water content and CO2 concentration on CO2 absorption character were studied by a microchannel reactor. Under appropriate conditions, CO2 absorption efficiency could reach 99.95 %. The addition of promoter PZ could significantly enhance CO2 absorption performance. Additionally, desorption energy consumption of DES solution after CO2 saturation is lower than that of the standard 30 wt% MEA solution, which proves process friendliness of the DES. This study not only provides technical support but also sheds light on the potential applications of DESs in CO2 capture.