PC-SAFT Modeling of CO2 Solubilities in Deep Eutectic Solvents

Area of Science:

• Physical Chemistry
• Chemical Engineering
• Thermodynamics

Background:

• Deep eutectic solvents (DESs) are novel liquid mixtures formed from solid hydrogen bond donors (HBDs) and acceptors (HBAs).
• Understanding the phase behavior of DESs with gases like CO2 is crucial for applications such as carbon capture and storage.

Purpose of the Study:

• To apply the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) to model the vapor-liquid equilibria (VLE) of DESs with CO2.
• To compare two PC-SAFT modeling strategies: the pseudo-pure component approach and the individual-component approach.

Main Methods:

• PC-SAFT modeling was employed using lactic acid as the HBD and various tetraalkylammonium chlorides as HBAs.
• Two strategies were tested: treating the DES as a single pseudo-pure component or as individual HBD and HBA components.
• Binary interaction parameters were fitted to experimental VLE data for DES + CO2 systems.

Main Results:

• The individual-component approach provided quantitative predictions for DES + CO2 phase behavior across various molar ratios.
• The pseudo-pure component approach required DES-composition specific interaction parameters for accurate modeling.
• Experimental VLE data for DES + CO2 systems were measured and used for model validation.

Conclusions:

• The individual-component strategy in PC-SAFT is superior for predicting the phase behavior of DES + CO2 systems.
• This finding facilitates the design and optimization of processes involving DESs and CO2.