Multiphase equilibria in systems containing ionic liquids: Experimental investigations of phenomena and molecular modeling

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The phase equilibrium phenomenon salting-out by a nearcritical gas (SONG) in liquid mixtures of ionic liquids is to be explored in both experimental and theoretical work. That particular phenomenon is characterized by a liquid-liquid phase split of (otherwise completely miscible) liquids by pressurization with a gas under conditions which are close to the critical point of vapor-liquid equilibrium of the gas. The SONGphenomenon is expected to enable higher conversion rates in chemical processes and/or an economical extraction of the reaction products. The phenomenon is to be explored for two typical systems, an aqueous system and a nonaqueous system of an ionic liquid. The experimental work is to be supplemented by theoretical work which is aiming to predict such complex high-pressure multiphase equilibria in systems with ionic liquids by molecular simulation (Gibbs Ensemble Monte Carlo Simulations). The intermolecular pair-potentials are already available for the gaseous component and the second (low-molecular) solvent (e.g. water, hexane), but the intermolecular pairpotential of the ionic liquid is to be determined by applying quantum chemistry based models. The mixed interactions have to be determined by mixing rules . That method was recently successfully tested in the applicant s group for predicting the solubility of gases in pure ionic liquids. It provides strong insights into the molecular properties that govern the phase equilibrium in systems with ionic liquids, and the method is also is expected to allow for the reliable prediction of the SONG-phenomenon.