Thermodynamic and Kinetic Studies of CO2 Capture by Glycol and Amine-Based Deep Eutectic Solvents

Anthropogenic CO2 emissions into the atmosphere are responsible for the global warming, therefore, it is essential to reduce these emissions at the source. Recently, deep eutectic solvents (DESs) have shown great potential to absorb the CO2. In the current study, 15 different types of amine- and glycol-based deep eutectic solvents were synthesized and investigated for CO2 absorption. In general, amine based solvents have shown higher CO2 absorption as compared to glycol based solvents. In particular, the highest CO2 absorption was observed for the tetrabutyl ammonium bromide and methyldiethanol amine (TBAB/4MDEA) system having a CO2 solubility of 0.29 (mol CO2/mol solvent) at 1 MPa and 303.15 K. Thermophysical properties of all synthesized DESs were estimated using the modified Lydersen-Joback-Reid method and Lee-Kesler mixing rule. Experimental CO2 solubility data were well fitted using the nonrandom two liquid and the Peng-Robinson thermodynamic models. Apart, CO2 solubility data were correlated with Henry's law, and Henry's constant was calculated for all DESs. The kinetic modeling of CO2 absorption in DESs was also studied and rate constants were evaluated.