Abstract
An investigation of the Lewis acid-base interactions between aromatic hydrocarbons and an entrainer cosolvent using vapor-liquid equilibrium data and Fourier transform infrared (FT-IR) spectra is presented. High-pressure vapor-liquid equilibria of several ternary and quaternary systems containing aromatic hydrocarbons, an entrainer, and supercritical carbon dioxide or ethane as a diluent are measured using a dynamic system in which both the vapor and liquid phases are circulated. The aromatic hydrocarbons that are used in this study are anisole, benzaldehyde, and 1-methylnaphthalene, and the entrainer is methanol. The phase equilibria of the ternary and quaternary systems containing carbon dioxide are measured at 373 K and pressures up to 22 MPa. For the ethane systems, equilibrium measurements are made at 372 K and pressures up to 12 Mpa. Enhancement factors determined for anisole and benzaldehyde were found to increase with the addition of methanol as a cosolvent.
Additionally, the thermodynamic relations for two multicomponent fluid phases in equilibrium, in which there are associating components in both phases, are examined. We show that the solubility depends on extent of hydrogen bonding of the solute in both phases. For mixtures in which only the solute and cosolvent associate, the solubility of the solute is shown to explicitly depend on the partitioning of the cosolvent between the two phases.