Vapor-liquid equilibria in quaternary mixtures of dimethyl ether plus n-butane plus ethanol plus water

The vapor-liquid equilibria, liquid densities, and liquid-liquid phase sepa ration of the quaternary system dimethyl ether (DME) + n-butane + ethanol water were determined at 293.15 K. The vapor-liquid equilibria were measur ed for mixtures with 0-70 wt % dimethyl ether, 0-40 wt % n-butane, 0-70 wt % ethanol, and 0-35 wt % water, depending on the presence of a second liqui d phase. The experiments were carried out in a static vapor pressure appara tus. The UNIQUAC model was used to perform the necessary corrections of the measured vapor-liquid equilibrium data. On the basis of the Gibbs-Duhem eq uation and experimental data, a set of parameters for this model was calcul ated. Using the parameters in the UNIQUAC model, it was possible to describ e the quaternary as well as some of the ternary and all six binary subsyste ms.