Modeling of Ionic Liquid Binary and Ternary Mixture Phase Equilibria at Low and High Pressure With the tPC-PSAFT
Sustainable process-product development & green chemistry
Modelling of Ionic Liquids (T1-1)
Keywords: Ionic Liquids, Phase Equilibria, Thermodynamic Modelling, tPC-PSAFT
Ionic Liquids (ILs) have unique physical properties compared to traditional solvents and in recent years have emerged as suitable alternatives for the development of efficient and environment friendly chemical processes. Accurate knowledge of thermodynamic properties and phase equilibria of IL mixtures with organic solvents, water, carbon dioxide and other widely used compounds is a definite prerequisite in order that such mixtures are considered in an industrial process. Experimental measurements as well as accurate thermodynamic models can be used in this respect. In this work, a molecular thermodynamic model based on truncated Perturbed Chain-Polar Statistical Associating Fluid Theory is developed for the prediction / correlation of IL binary and ternary mixtures. tPC-PSAFT accounts explicitly for size and shape differences between unlike molecules and also for different intermolecular forces, including van der Waals forces, polar forces (due to permanent dipoles and quadrupoles) and hydrogen bonding forces between like (self-association) and unlike (cross-association) molecules. As a result, tPC-PSAFT can be used reliably for thermodynamic and phase equilibria calculations over a wide temperature and pressure range.
Here, the model is used to correlate high pressure phase equilibria data for IL – CO2 and IL – H2O mixtures as well as ternary IL mixtures measured in Delft. In addition, literature phase equilibria data for various IL mixtures are considered. In the current theoretical framework, IL molecules are considered as molecular species with high dipole moment and no ion dissociation is considered. The protocol for model parameter estimation for ILs is developed based on well justified theoretical considerations. The absence of vapor pressure data for ILs calls for an alternative way for parameter estimation compared to what is used for other non-polymer compounds. Binary interaction parameters are fitted to experimental data and used with non further adjustment to predict ternary mixture phase equilibria. For most of the mixtures examined, the agreement between experimental data and model correlation / prediction is very good. In some cases, deviations are observed that require further attention and possible refinement of the model.
Preferred type of presentation: Oral
Presented Monday 17, 11:33 to 11:51, in session Modelling of Ionic Liquid Systems (T1-1).
