The Physicochemical Properties of Benzyltriethylammonium Chloride-Based Deep Eutectic Solvents and the Corresponding CO ₂ Solubility

Under the guidance of the “dual-carbon” strategy, the development of low-energy-consumption and environmentally friendly solvents for CO2 capture is of great importance. In this study, six deep eutectic solvents (DESs) were prepared using benzyltriethylammonium chloride (TEBAC) as the hydrogen bond acceptor (HBA), and ethylene glycol (EG) and diethylene glycol (DEG) as the hydrogen bond donors (HBD). The density and viscosity were systematically determined in the temperature range of 303.15–333.15 K. The CO2 solubility was measured at temperatures from 303.15 to 333.15 K and pressures up to 2.3 MPa. The DES containing DEG at a 1:3 molar ratio exhibited the highest CO2 solubility, reaching 0.132 at 303.15 K and 1.98 MPa. The PR-NRTL and the modified Krichevsky–Kasarnovsky model were adopted to correlate the solubility data, with absolute average relative deviation of 1.40 and 1.11%, respectively. Furthermore, thermogravimetric analysis (TGA) was used to evaluate the thermal stability, and cyclic experiments were conducted to examine the regeneration performance. Fourier transform infrared spectroscopy (FTIR) was applied to reveal the CO2 absorption mechanism. This study provides systematic experimental data and theoretical support for the application of quaternary ammonium salt–alcohol DESs in the CO2 capture processes.