Search

Liquid–liquid equilibria at ambient temperature and pressure were measured for four ternary systems: n-hexane + THF + water, n-hexane + acetonitrile + water, n-hexane + 1,4-dioxane + water, and ethyl ether + 1,4-dioxane + water. Partitioning of 1-octene and 1-nonanal in these systems was also measured. The results were modeled with the UNIQUAC and NRTL gE models. The experiments showed an aqueous phase in the n-hexane–THF–water system that was 90% water on average, and an organic n-hexane phase in the n-hexane–acetonitrile–water system that was 96% n-hexane on average. 1,4-Dioxane distributes fairly equally to both phases in the n-hexane–1,4-dioxane–water and ethyl ether–1,4-dioxane–water systems.

Homogeneous catalysts offer many advantages over heterogeneous catalysts, such as higher activities and selectivities. However, recovery of homogeneous catalysts is often complicated by difficulties in separating these complexes from the reaction products. The use of gaseous carbon dioxide (CO2) as miscibility switch for organic and fluorous phases has been proposed to overcome this limitation. By using CO2 as a cosolvent, polar organic reactants can be homogenized with catalysts immobilized in a fluorous phase without using elevated temperatures. The phase behavior underlying this concept is investigated. High-pressure phase equilibria for the systems containing carbon dioxide, an organic (methanol, toluene, or acetone), and perfluoro-n-hexane were measured using a variable-volume view cell, by a method capable of rapid and facile measurement of compositions and density in both phases with no sampling or calibration.

Homogeneous catalysts offer better activity and selectivity than heterogeneous catalysts, but their use is limited by the need to separate them from product and reuse them. Preferential dissolution of gaseous carbon dioxide has been shown to alter phase boundaries and facilitate recovery of such homogenous catalysts. The addition of a polar organic co-solvent to a water/organic biphasic system, coupled with subsequent phase splitting induced by the dissolution of gaseous carbon dioxide creates the opportunity to run homogeneous reactions in an organic/aqueous mixture with a water-soluble catalyst. In homogeneous catalyzed reactions, the catalyst can be tuned to be soluble or insoluble with carbon dioxide present, thus allowing for high catalyst recovery. High-pressure phase equilibria for the systems containing carbon dioxide, an organic (tetrahydrofuran, acetonitrile, or 1,4-dioxane), and water were measured using a variable-volume view cell, by a method capable of rapid and facile measurement of compositions and density in both phases with no sampling or calibration. These systems are well predicted with the Peng–Robinson Equation of State with Huron–Vidal type mixing rules from correlations of the binary systems, with the modified Huron–Vidal 1 (MHV1) and Huron–Vidal–Orbey–Sandler (HVOS) model with UNIQUAC excess energy model performing the best. Applications of the phase behavior on reaction conditions and separations are addressed.

Solid–fluid equilibria are important for supercritical fluid processing design. Few data are available, and predictions require a model for the solute–solvent interactions. An activity coefficient model for solids in supercritical CO2, based on linear solvation energy relationships, is developed. The model fits solubility data at liquid-like densities to an average error of 65%. Extrapolations to gas-like densities are shown.