LIQUID-LIQUID EQUILIBRIA OF FUEL OXYGENATE PLUS WATER PLUS HYDROCARBON MIXTURES .3. EFFECT OF TEMPERATURE

We have measured the ternary liquid-liquid equilibria of water + ethan ol mixtures with, separately, 2,2,4-trimethylpentane and toluene at 5 and 40 degrees C, water + tert-amyl alcohol (TAOH) mixtures with, sepa rately, toluene and hexane at 5 and 40 degrees C, and of water + TAOH + pentane mixtures at 5 degrees C. The ethanol-containing systems exhi bit type 1 Liquid-Liquid phase behavior, and the TAOH-containing syste ms exhibit type 2 behavior. These data, together with the data we have previously reported at 25 degrees C, provide information on how the l iquid-liquid equilibria of these systems change as a function of tempe rature. While the addition of ethanol is found to increase the solubil ity of hydrocarbons in the aqueous phase, the concentration of the hyd rocarbon in the water-rich phase decreases with increasing temperature . With the exception of the hydrocarbon in the water-rich phase, our e xperimental data could be correlated quite well with either the UNIQUA C or NRTL models. For most of the systems considered here the predicti ons of the phase behavior with the liquid-liquid UNIFAC group-contribu tion model are only qualitatively correct. However, the liquid-liquid UNIFAC model erroneously predicts type 2 phase behavior to occur for t he water + ethanol + 2,2,4-trimethylpentane system at 5 degrees C.