VAPOR-LIQUID-EQUILIBRIUM DATA FOR ETHANOL-N-HEPTANE 1-PROPANOL AND ETHANOL-N-HEPTANE-2-PROPANOL AND THEIR INTERPRETATION BY A SIMPLE ASSOCIATION MODEL

Vapor-liquid equilibrium measurements are reported for ethanol n-heptane-1-propanol and for ethanol n-heptane-2-propanol at 303.15 K. The data consist of total pressure as a function of liquid phase composition and were measured in a Van Ness apparatus. Theoretical results presented by Nagata and Ohtsubo (Nagata, I. and Ohtsubo, K., 1986. Thermochim. Acta, 102: 185 205) were used to develop a simple association model applicable to ternary systems which contain two alcohols and a hydrocarbon. In addition to an equilibrium constant for each alcohol, the model requires a single physical parameter for each hydrocarbon alcohol pair and a cross-association constant for each alcohol-alcohol pair. For binary alcohol hydrocarbon systems, the model reduces to that of Renon and Prausnitz (Renon, H. and Prausnitz, J.M., 1967. Chem. Eng. Sci., 22: 299-307). The model represents the data reported in this paper, as well as data from the literature, with good accuracy.