Development of Natural Hydrophobic Deep Eutectic Solvents for Precombustion CO2 Capture

Hydrophobic deep eutectic solvents (DESs) have been designed as effective solvents for precombustion CO2 capture by using a conductor-like screening model for real solvents (COSMO-RS). Reliable CO2 solubilities in various compounds and binary solvents were estimated. We have developed new DESs from 38 selected, nature-derived, hydrophobic, and CO2 affinitive compounds. The possibilities of any two of these substances to form DESs were assessed from predicted activity coefficients, followed by an estimation of the CO2 solubilities of the theoretically feasible DESs. 58 promising hypothetical DESs were screened out. Subsequently, eight DESs were successfully prepared and characterized. Most of these DESs have a density larger than 1.0 g/mL at 298.15 K. The DESs have a similarly low volatility as decanoic acid–menthol (1:2) and are thermally stable below 420 K. Vanillin-4-oxoisophorone (1:3) and methyl salicylate-4-oxoisophorone (1:1) have been identified to be very promising for precombustion capture, showing comparable CO2 solubility and viscosity to the well-known, conventionally used Selexol solvent.