Investigation of effective CO2 capture by ternary deep eutectic solvents based on superbase

The absorption and separation of CO 2 is one of the main strategies to reduce carbon emissions and mitigate global climate change. In this context, a series of ternary superbase/betaine-based deep eutectic solvents (DESs) were synthesized to capture CO 2 , and their density, viscosity and thermal stability were investigated. The effects of temperature, pressure, different hydrogen bond donors (HBDs) and alkalinity of the superbase on their CO 2 affinity were evaluated by the isovolumetric saturation method. The uptake of CO 2 by the DES synthesized from betaine, 1,2-propanediol and 1,8-diazabicyclo(5.4.0)undec-7-ene reached a maximum of 1.5071 mol·kg −1 at 303.15 K and a pressure of 0.187 MPa. The simultaneous chemical and physical adsorption of CO 2 by the ternary DESs was verified by FTIR spectroscopy, and the absorption mechanism was also proposed. The reaction equilibrium thermodynamic model (RETM) was improved to obtain the “Active DES” model, which was correlated with the experimentally determined CO 2 solubility. The reaction equilibrium constants and Henry's law constants were obtained for each ternary system. The ternary superbase/betaine DESs proposed in this paper are green, economical and high-performance absorbers for capturing CO 2 .