Preparation and Properties of a High-Performance Deep Eutectic Solvent ChCl-AEEA for Carbon Dioxide Capture

Deep eutectic solvents (DESs) have emerged as a new class of eco-friendly solvents for carbon dioxide (CO₂) capture due to their excellent properties and good stability. In this work, a high-performance deep eutectic solvent ChCl-AEEA absorbent with choline chloride (ChCl) as a hydrogen bond acceptor (HBA) and aminoethyl ethanolamine (AEEA) as a hydrogen bond donor (HBD) was prepared. The formation process of the ChCl-AEEA was determined by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC); the effects of AEEA proportion in the DES β, water content ω_H2O, temperature T, and pressure p_CO2 on the CO₂ absorption capacity of the DES were investigated. The results showed that the CO₂ absorption capacity α of the DES could be as high as 0.8528 mol of CO₂/mol of DES (0.3373 g of CO₂/g of DES) at 313.2 K and 0.1 MPa when ω_H2O was 51.9 wt % and β was 0.8. The corresponding absorption heat was measured to be −48.34 kJ/mol, indicating a low energy consumption for desorption. The absorption capacity of the DES did not change after five absorption and desorption cycles. The absorption of CO₂ in the prepared DES was chemical absorption, which was confirmed by FTIR and the ¹³C nuclear magnetic resonance (¹³C NMR) spectrum.