HIGH-TEMPERATURE AND HIGH-PRESSURE WATER SOLUBILITY IN ETHYLBENZENE TO 200°C AND 1 KBAR AND THE ACETIC ACID EFFECT

Abstract

Water solubility in hydrocarbon systems is of great interest for deep oil fields. A new autoclave has been designed to measure phase equilibria in water-hydrocarbon systems up to 400°C and 1.5 kbar. It has been applied for the measurement of water solubility in ethylbenzene with or without acetic acid to 200°C and 1 kbar in the two-phase field. Water solubility was measured by the Karl Fisher method. The acetic acid concentration was measured by FT-IR microspectroscopy. Both the experimental procedure and analytical techniques were validated by showing the consistency of our data with those of Heidman et al. (“High-temperature mutual solubilities of hydrocarbons and water,” AIChE J.31, 376–384, 1995) along the liquid-liquid-vapor curve. At constant pressure, the solubility of water in ethylbenzene increases significantly with temperature. On the other hand, at constant temperature, the solubility of water is constant to 1 kbar at 100°C, and decreases slightly with pressure at 150 and 200°C. Data were regressed by the Krichevsky-Kasarnovsky equation to obtain estimates of the Henry’s law constant and estimates of the molar volume of water at infinite dilution. Acetic acid increases the solubility of water in ethylbenzene and fractionates preferentially into the aqueous phase.