Fluid Phase Equilibria 342 (2013) 52–59 Contents lists available at SciVerse ScienceDirect Fluid Phase Equilibria journa l h o me page: www.elsevier.com/locate/fluid Experimental determination and theoretical modeling of the vapor–liquid equilibrium and densities of the binary system butan-2-ol + tetrahydro-2H-pyran Héctor Quinteros-Lama, Marcela Cartes, Andrés Mejía ∗∗ , Hugo Segura ∗ Departamento de Ingeniería Química, Universidad de Concepción, POB 160-C, Correo 3, Concepción, Chile a r t i c l e i n f o Article history: Received 31 October 2012 Received in revised form 13 December 2012 Accepted 18 December 2012 Available online 17 January 2013 Keywords: Vapor–liquid equilibrium Mixing volumes THP Butan-2-ol Association Polar perturbed chain statistical association fluid theory (PPC-SAFT) a b s t r a c t Isobaric vapor–liquid equilibrium (VLE) data have been measured for the binary system butan-2- ol + tetrahydro-2H-pyran at 50, 75, and 94 kPa and over the temperature range from 339 to 370 K using a vapor–liquid equilibrium still with circulation of both phases. Mixing volumes were also determined at 298.15 K and atmospheric pressure with a vibrating tube densimeter. According to experimental results, the zeotropic mixture exhibits slight positive deviation from ideal behavior over the experimental range. The excess molar volumes (˜ v E ) of the system are positive over the whole mole fraction range. The VLE data of the binary mixture satisfy the Fredenlund’s consistency test and were well-correlated by the Wohl, nonrandom two-liquid (NRTL), Wilson, and universal quasichemical (UNIQUAC) equations for all of the measured isobars. The ˜ v E , in turn, were satisfactorily correlated using a second order Redlich–Kister equation. The theoretical modeling of the measured VLE and ˜ v E data has been carried out using the polar per- turbed chain statistical association fluid theory (PPC-SAFT) equation of state. In this molecular based approach, butan-2-ol was described as a polar auto-associating molecule, while tetrahydro-2H-pyran is treated as polar molecule. Molecular interactions between these two components have been approxi- mated in terms of a hetero-association theory. It is demonstrated that a common set of parameters is able to simultaneously reproduce with good agreement both phase equilibrium and excess molar volumes measurements. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Cyclic ethers (such as tetrahydrofuran or THF, 1,4-dioxane and tetrahydro-2H-pyran or THP) can be traditionally found in several industrial applications as solvents and separation agents [1,2] and, additionally, as reportedly established in the case of cyclic ethers of the family of furans, they may constitute alternative additives for producing low pollutant hydrocarbon fuels, or biofuels [3–5]. When compared to traditional branched ethers, as the case of methyl tert-butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME); cyclic ethers of comparable molecular weight exhibit similar boiling tempera- tures, although they are characterized by more attractive properties for fuel blending such as higher densities and surface tensions [3]. In spite of their importance, experimental and theoretical inves- tigations concerning to the description of key thermo-physical ∗∗ Corresponding author. Fax: +56 41 2203897. ∗ Corresponding author. Fax: +56 41 2247491. E-mail addresses: amejia@udec.cl (A. Mejía), hsegura@udec.cl (H. Segura). properties of some members of cyclic ethers – particularly the case of THP and its mixtures – are scarce, incomplete or limited to narrow experimental conditions (see Ref. [5] and references therein). As indicated by Uno et al. [6], THP may be produced from hydrogen, acetaldehyde, alcohol, and acrolein. By means of the quoted synthesis route, the alcohol is necessary to ensure zeotropic behavior thus facilitating distillation. However, to the best of our knowledge, no density data have been reported previously for butan-2-ol + THP. In addition, only partial T–x vapor–liquid equi- librium (VLE) data have been measured for the quoted mixture by Uno et al. [6] over the pressure range 40–98.66 kPa. According to the measurements provided by these authors, namely boiling temperatures at known liquid phase mole fractions, the mixture exhibits positive deviation from ideal behavior and no azeotrope is present. As part of our ongoing research program devoted to the char- acterization of the thermo-physical properties of THP mixtures (THP + n-alkanes [5] + alcohols [7]), this work is undertaken to determine complete and consistent VLE data and densities of 2-butanol + THP and, additionally, to analyze its phase behavior at the light of well established theories for associated solu- tions. 0378-3812/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.fluid.2012.12.021