Search

• The cubic-two-states equation of state was applied to correlate the vapor-liquid and liquid-liquid equilibria of nitriles + hydrocarbons experimental data. • The approach was extended to predict ternary liquid-liquid equilibria of nitriles + 2 hydrocarbons mixtures. • The approach was extended to predict ternary liquid-liquid equilibria of acetonitrile + n -octane + benzothyophene and acetonitrile + n -octane + benzothyophene 1,1 dioxide. The cubic-two-state (CTS) equation of state (EoS) was employed for modeling the liquid-liquid and vapor-liquid equilibria of nitriles + hydrocarbons (alkanes and aromatics) or water mixtures. For nitriles, the five pure compound parameters were determined by fitting the model simultaneously to experimental saturation pressure, density of saturated liquid, enthalpy of vaporization and liquid-liquid equilibrium data when mixed with n-dodecane. For alkanes, the pure parameters were those determined from conventional corresponding states correlations for Soave-Redlich-Kwong EoS. The van der Waals mixing and combining rules were applied for dispersive parameter and covolume, with a temperature-dependent binary parameter. In the case of nitrile mixtures with aromatics and water, cross-association were considered with the previously published CTS combining rules, and no association binary parameters were required. The correlations were very good in all cases. The model was also able to predict selective extraction of sulfur compounds (benzothyophene and benzothyophene 1,1-oxide) from alkanes. Because of its simplicity, therefore, the CTS EoS is a very attractive option for process simulation involving this class of mixtures. [Display omitted] [ABSTRACT FROM AUTHOR]

The cubic two-state equation of state was employed for the correlation of measured mutual solubilities of water and 68 hydrocarbons. A new Kabadi-Danner's type mixing rule is presented, in which the water-water dispersive parameter of the cubic part is corrected due to the presence of a hydrophobic solute. The obtained binary parameters for the water-hydrocarbon pairs had a marked relationship with the chemical family (alkanes, cycloalkanes, aromatics, and unsaturated aliphatics) and with the co-volumes. This allowed the development of general correlations to predict these parameters in the case of lack of experimental solubilities. The model's overall deviations from measured data were 12% and 16% for the solubilities of water in hydrocarbons and of hydrocarbons in water, respectively. The temperature and pressure ranges of the correlated data were 273.2 to 550 K and 1 to 1000 bar, respectively. To check model reliability, the correlations were successfully extended to predict bubble pressures and dew temperatures of water-hydrocarbon binaries and ternaries and mutual solubilities in multi-hydrocarbon mixtures. [ABSTRACT FROM AUTHOR]

The combination of the gradient theory of inhomogeneous interfaces (GTII) with cubic plus association equation of state (CPA EoS) was applied for the correlation of liquid–liquid interfacial tensions of water-hydrocarbons mixtures (alkanes and aromatics) as a function of temperature and pressure. In order to give predictive capability to the proposed method, all binary parameters of the CPA EoS were set to zero, except for aromatics in which one solvation and one binary parameter are required for appropriate description of phase equilibria. GTII was employed in the Helmholtz energy framework, assuming no volume change upon mixing. For binary mixtures, this approximation avoids the time consuming density profile computation and it makes the calculations similar when using excess Gibbs energy models. Only one adjustable constant was necessary to correlate interfacial tensions with less than 1% deviation, in the range of temperatures of the available experimental data. This constant corrects the geometrical mean rule in the estimation of cross influence parameters. The overall average deviation from measured interfacial tensions at 0.1 MPa (0.14 mN/m) is similar to the reported experimental errors (from 0.04 to 0.4 mN/m). Using the parameters determined at 0.1 MPa, the effect of pressure over the interfacial tensions were determined. The proposed model, in general, over-predicts interfacial tensions, especially at very high pressures. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new mixing rule for CPA EoS to correlate water–hydrocarbon mutual solubilities is presented. [•] The new mixing rule has only one additional binary parameter. [•] The binary parameters were determined for alkanes, cycloalkanes and aromatics. [•] The CPA EoS with the new mixing rule is able to describe the minimum HC solubility vs temperature curves. [•] The new mixing rule was successfully employed for multicomponent mixtures. [ABSTRACT FROM AUTHOR]