Phase equilibria, critical behavior and derivative properties of selected n-alkane/n-alkane and n-alkane/1-alkanol mixtures by the crossover soft-SAFT equation of state

We present here results from the crossover soft-SAFT equation of state as applied to selected n-alkane/n-alkane and n-alkane/1-alkanol mixtures. The molecular parameters needed to apply the equation to experimental systems were obtained as a function of the molecular weight of the compounds, from published correlations. The fact that the equation takes into account the long range density and composition fluctuations appearing near the critical point enables it to predict with equal accuracy the behavior of the systems far from and close to the critical region. We have found that, for most of the mixtures investigated here, one size binary interaction parameter, with a fixed value for all systems, is enough to quantitatively predict the rich phase behavior shown by these mixtures, while for the case of very asymmetric mixtures, a second binary parameter, also independent of the thermodynamic conditions, is needed to quantitatively describe experimental data. Crossover soft-SAFT accurately reproduces transitions from type I to type V for the critical behavior of the methane/n-alkane and ethane/n-alkane homologous series. The equation also predicts in a quantitative manner the subcritical and critical behavior of the 1-propanol/n-hexane and ethanol/n-butane binary mixtures. Finally, we report speed of sounds of the mixture methane/n-butane and the heat capacities of the mixture 1-propanol/n-decane, in close agreement with experimental data. Results presented here encourage the development of molecular-based equations of state with a term taking into account the singular behavior in the near critical region, especially if one is searching for quantitative predictions in this region for further applications.

[1]  A. Danesh,et al.  Measurements of the Speed of Sound for Mixtures of Methane + Butane with a Particular Focus on the Critical State , 2005 .

[2]  Fèlix Llovell,et al.  Global fluid phase equilibria and critical phenomena of selected mixtures using the crossover soft-SAFT equation. , 2006, The journal of physical chemistry. B.

[3]  Gabriele Sadowski,et al.  Perturbed-Chain SAFT: An Equation of State Based on a Perturbation Theory for Chain Molecules , 2001 .

[4]  S. B. Kiselev,et al.  Predicting mixture phase equilibria and critical behavior using the SAFT-VRX approach. , 2005, The journal of physical chemistry. B.

[5]  Leo Lue,et al.  Renormalization-group corrections to an approximate free-energy model for simple fluids near to and far from the critical region , 1998 .

[6]  George Jackson,et al.  New reference equation of state for associating liquids , 1990 .

[7]  Jianwen Jiang,et al.  Equation of state for thermodynamic properties of chain fluids near-to and far-from the vapor–liquid critical region , 1999 .

[8]  George Jackson,et al.  Phase equilibria of associating fluids , 2006 .

[9]  M. Wertheim,et al.  Fluids with highly directional attractive forces. II. Thermodynamic perturbation theory and integral equations , 1984 .

[10]  Fèlix Llovell,et al.  Thermodynamic properties of Lennard-Jones chain molecules: renormalization-group corrections to a modified statistical associating fluid theory. , 2004, The Journal of chemical physics.

[11]  Liming W. Salvino,et al.  Calculation of density fluctuation contributions to thermodynamic properties of simple fluids , 1992 .

[12]  Hwayong Kim,et al.  Vapor–liquid equilibria for the system 1-propanol+n-hexane near the critical region , 2004 .

[13]  J. Prausnitz,et al.  Thermodynamics for fluid mixtures near to and far from the vapor–liquid critical point , 2004 .

[14]  P. H. van Konynenburg,et al.  Critical lines and phase equilibria in binary van der Waals mixtures , 1980, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[15]  Fèlix Llovell,et al.  Prediction of thermodynamic derivative properties of pure fluids through the Soft-SAFT equation of state. , 2006, The journal of physical chemistry. B.

[16]  Jianguo Mi,et al.  Prediction of global VLE for mixtures with improved renormalization group theory , 2006 .

[17]  K. Wilson.  Renormalization Group and Critical Phenomena. I. Renormalization Group and the Kadanoff Scaling Picture , 1971 .

[18]  T. W. Loos,et al.  High pressure VLE in alkanol + alkane mixtures. Experimental results for n-butane + ethanol, +1-propanol, +1-butanol systems and calculations with three EOS methods , 1995 .

[19]  Josep C. Pàmies,et al.  SAFT Modeling of the Solubility of Gases in Perfluoroalkanes , 2004 .

[20]  Michael E. Fisher,et al.  Critical Exponents in 3.99 Dimensions , 1972 .

[21]  K. Gubbins,et al.  Predictions of the Joule-Thomson Inversion Curve for the n-Alkane Series and Carbon Dioxide from the Soft-SAFT Equation of State † , 2002 .

[22]  Daniel Duque,et al.  Interfacial properties of Lennard-Jones chains by direct simulation and density gradient theory. , 2004, The Journal of chemical physics.

[23]  R. Sadus.  High Pressure Phase Behaviour of Multicomponent Fluid Mixtures , 1992 .

[24]  M. Wertheim,et al.  Fluids with highly directional attractive forces. III. Multiple attraction sites , 1986 .

[25]  B. Sage,et al.  Phase Equilibria in Hydrocarbon Systems. Volumetric and Phase Behavior of the n-Decane-CO2 System. , 1963 .

[26]  L. Vega,et al.  Critical behavior and partial miscibility phenomena in binary mixtures of hydrocarbons by the statistical associating fluid theory , 1998 .

[27]  Zhou,et al.  Escape-time distributions of a periodically modulated bistable system with noise. , 1990, Physical review. A, Atomic, molecular, and optical physics.

[28]  Albright,et al.  Crossover from singular critical to regular classical thermodynamic behavior of fluids. , 1990, Physical review. A, Atomic, molecular, and optical physics.

[29]  Jianguo Mi,et al.  Renormalization group theory for fluids including critical region. I. Pure fluids , 2004 .

[30]  Reatto,et al.  Comprehensive theory of simple fluids, critical point included. , 1989, Physical review letters.

[31]  Josep C. Pàmies,et al.  Solubility of hydrogen in heavy n‐alkanes: Experiments and saft modeling , 2003 .

[32]  Erich A. Müller,et al.  Molecular-Based Equations of State for Associating Fluids: A Review of SAFT and Related Approaches , 2001 .

[33]  Josep C. Pàmies,et al.  Thermodynamic properties and aggregate formation of surfactant-like molecules from theory and simulation. , 2004, The Journal of chemical physics.

[34]  P. S. Chappelear,et al.  Dew-point loci for methane-n-pentane binary system , 1974 .

[35]  I. Polishuk,et al.  Prediction of the critical locus in binary mixtures using equation of state: II. Investigation of van der Waals-type and Carnahan–Starling-type equations of state , 1999 .

[36]  Ioannis G. Economou,et al.  Statistical Associating Fluid Theory: A Successful Model for the Calculation of Thermodynamic and Phase Equilibrium Properties of Complex Fluid Mixtures , 2002 .

[37]  K. D. Luks,et al.  Solubility of ethane in n-decane at pressures to 8.2 MPa and temperatures from 278 to 411 K , 1986 .

[38]  George Jackson,et al.  Statistical associating fluid theory for chain molecules with attractive potentials of variable range , 1997 .

[39]  J. A. White,et al.  Contribution of fluctuations to thermal properties of fluids with attractive forces of limited range: theory compared with PϱT and Cv data for argon , 1992 .

[40]  P. S. Chappelear,et al.  Vapor-liquid equilibrium of the methane-n-hexane system at low temperature , 1977 .

[41]  Josep C. Pàmies,et al.  Phase equilibria of ethylene glycol oligomers and their mixtures , 2005 .

[42]  John A. Zollweg,et al.  The Lennard-Jones equation of state revisited , 1993 .

[43]  Stanley H. Huang,et al.  Equation of state for small, large, polydisperse, and associating molecules , 1990 .

[44]  S. B. Kiselev,et al.  Cubic crossover equation of state for mixtures , 1999 .

[45]  P. S. Chappelear,et al.  Vapor-liquid equilibrium of methane-n-pentane system at low temperatures and high pressures , 1972 .

[46]  J. Gregorowicz.  Solubility of tetracosane in supercritical ethane and ethylene , 2003 .

[47]  C. Peters,et al.  Second-order thermodynamic derivative properties of selected mixtures by the soft-SAFT equation of state , 2006 .

[48]  B. Sage,et al.  Phase behavior in binary and multicomponent systems at elevated pressures: n-pentane and methane-n-pentane , 1970 .

[49]  S. B. Kiselev,et al.  Cubic crossover equation of state , 1998 .

[50]  K. Wilson.  Renormalization Group and Critical Phenomena. II. Phase-Space Cell Analysis of Critical Behavior , 1971 .

[51]  J. Sengers,et al.  Critical fluctuations and the equation of state of Van der Waals , 2004 .

[52]  I. Polishuk,et al.  Simultaneous Prediction of the Critical and Subcritical Phase Behavior in Mixtures of Ethane-n-Alkanes , 2005 .

[53]  Jianguo Mi,et al.  Renormalization group theory for fluids including critical region. II. Binary mixtures , 2005 .

[54]  C. P. Hicks,et al.  Gas-liquid critical properties of binary mixtures , 1975 .

[55]  Lourdes F. Vega,et al.  Vapor−Liquid Equilibria and Critical Behavior of Heavy n-Alkanes Using Transferable Parameters from the Soft-SAFT Equation of State , 2001 .

[56]  G. Jackson,et al.  Predicting the High-Pressure Phase Equilibria of Methane + n-Hexane Using the SAFT-VR Approach , 1998 .

[57]  M. Wertheim,et al.  Fluids with highly directional attractive forces. IV. Equilibrium polymerization , 1986 .

[58]  Daniel Duque,et al.  Phase and interface behaviors in type-I and type-V Lennard-Jones mixtures: theory and simulations. , 2005, The Journal of chemical physics.

[59]  Lourdes F. Vega,et al.  THERMODYNAMIC BEHAVIOUR OF HOMONUCLEAR AND HETERONUCLEAR LENNARD-JONES CHAINS WITH ASSOCIATION SITES FROM SIMULATION AND THEORY , 1997 .

[60]  Lourdes F. Vega,et al.  Prediction of Binary and Ternary Diagrams Using the Statistical Associating Fluid Theory (SAFT) Equation of State , 1998 .

[61]  B. Sage,et al.  Phase Equilibria in Hydrocarbon Systems. Volumetric and Phase Behavior of the Ethane-n-Decane System. , 1962 .

[62]  C. A. Cerdeiriña,et al.  Isobaric heat capacities, densities, isentropic compressibilities and second-order excess derivatives for (1-propanol + n-decane) , 2002 .