Study on the CO 2 absorption performance of deep eutectic solvents formed by superbase DBN and weak acid diethylene glycol

Abstract Deep eutectic solvents (DESs), a new class of green solvents, have attracted considerable attention for CO 2 capture. In this study, we synthesised DESs using a superbase, 1,5-diazabicyclo [4.3.0] non-5-ene (DBN), as the hydrogen bond acceptor and a weak acid, diethylene glycol (DEG), as the hydrogen bond donor in different molar ratios to achieve efficient and reversible CO 2 absorption. Experimental results indicate that DES2 (DBN:DEG = 1:2) exhibits optimal CO 2 absorption performance (a maximum absorption capacity of 0.275 gCO 2 /gDES. Deep eutectic solvents at 30°C and flow rate of 30 mL/min). Nuclear magnetic resonance (NMR) spectroscopy reveals that DEG activated by DBN in DESs can react with CO 2 to form carbonates, thereby enabling CO 2 capture. In addition, monoethanolamine was added to the DESs as a promoter, thereby enhancing the CO 2 absorption performance, with a maximum absorption capacity of 0.316 gCO 2 /gDES. 13 C NMR and Fourier transform infrared analyses revealed that the amino and hydroxyl groups in the DESs can simultaneously react with CO 2 to form carbamate and carbonate, achieving synergistic absorption.