Superbase Ionic Liquid-Based Deep Eutectic Solvents for Improving CO2 Absorption

Carbon dioxide (CO 2 ) is a detrimental greenhouse gas to the environment as the main contributor to global warming. However, the development of efficient methods for CO 2 absorption and separation is still a great challenge. Ionic liquids (ILs) have emerged as promising solvents for CO 2 separation due to negligible vapor pressure and adjustable structures. In this work, a new strategy that three superbase ILs are designed as hydrogen bond acceptor (HBA) and further combined with ethylene glycol (EG) as hydrogen bond donor (HBD) to form novel IL-based deep eutectic solvents (DESs) was proposed for efficient and reversible absorption of CO 2 . The results indicated that both excellent recyclability and high CO 2 mass capacity up to 0.141 g CO 2 /g DES under 40 °C and 100 kPa are achieved by HDBUIm/EG with the mass ratio of 7:3, and the value is much higher than those of most of the reported IL-based DESs. The superior CO 2 absorption and desorption performances were attributed to the synergistic interaction between both IL and EG with CO 2 to form carbamate and carbonate, respectively. This work provides a feasible method for designing IL-based solvents in CO 2 separation applications.