Volumetric and derivative properties under pressure for the system 1-propanol + toluene. A discussion of PC-SAFT and SAFT-VR
Résumé
The density of the asymmetrical binary system 1-propanol + toluene has been measured (882 points) for nine different compositions including the pure compounds at seven isotherms in the range 293.15-353.15 K and 14 isobars up to 65 MPa with a vibrating-tube densimeter, the experimental uncertainty is estimated to be ±0.5 kg m-3. The isothermal compressibility, the isobaric thermal expansivity, and the excess molar volume have been derived. As a function of the composition, the isobaric thermal expansivity shows a non-monotonical behavior involving a maximum, whereas the excess molar volume reveals a complex sigmoid behavior. These results can be interpreted as due to changes in the molecular free-volume, disruption of the order molecular structure, and the breaking or formation of molecular interactions. Without using any binary interaction parameters or taking into account that electron donor-acceptor type of interactions exists between 1-propanol and toluene, PC-SAFT and SAFT-VR predict the density of this binary system within the considered temperature and pressure ranges with an overall AAD less than 0.5%. A satisfactory description of the azeotropic VLE behavior of the binary system is also found, whereas the derived properties, especially the isothermal compressibility, are not satisfactorily predicted.