Development of green solvents for efficient post-combustion CO2 capture with good regeneration performance

CO2 emission from post-combustion causes severe impacts on global environment. Hence, to minimize greenhouse effect, it is urgent to develop green solvents for CO2 capture. Herein, deep eutectic solvents (DES) were prepared using glycine (Gly) and proline (Pro) as hydrogen bond acceptors and monoethanolamine (MEA) and ethyl diethanolamine (MDEA) as hydrogen bond donors. The MEA-based DESs exhibited better CO2 uptake capability than MDEA-based DESs. The introduction of ethylene glycol (EG) to [Gly][MEA]/[Pro][MEA] not only enhances the absorption kinetics but also improves the regeneration ability. [Gly][MEA][EG] shows a better CO2 capture performance than [Pro][MEA][EG], reaching to 0.2485 g-CO2/g-DES after 6 h absorption at room temperature. [Gly][MEA][EG] shows an excellent tolerance to water content and CO2 concentration in flue gases and exhibits a robust performance in regeneration with no sustainable solvent loss after 10 cycles of recycles. NMR, FTIR and DFT results indicate that CO2 interacts with DESs via the formation of carbamate through the amine group in MEA and amino acids and via the formation of CO32-/HCO3- via the –OH group in EG. This study offers a novel green solvent for CO2 capture, which is feasible for industrial applications.