Vapor-Liquid equilibria measurement of carbon dioxide+1-hexene and carbon dioxide+2-ethyl-1-butene systems at high pressure

Pressure-composition isotherms were obtained for the carbon dioxide+1-hexene system at 40, 60, 80, 100 and 120 ‡C and pressure up to 120 bar and for carbon dioxide+2-ethyl-1-butene system at 40, 75 and 100 ‡C and pressure up to 115 bar. The accuracy of the experimental apparatus was tested by comparing the measured phase equilibrium data of the carbon dioxide+ 1-hexene system at 40 ‡C and 60 ‡C with those of Wagner and Wichterle 1987], and Jennings and Teja 1989]. The solubility of 1-hexene and 2-ethyl-1-butene for the carbon dioxide + 1-hexene and carbon dioxide+2-ethyl-1-butene systems increases as the temperatures increases at constant pressure. These two carbon dioxide-polar solute systems exhibit type-I phase behavior, which is characterized by an uninterrupted critical mixture curve that has a maximum in pressure. The experimental data are modeled by using the Peng-Robinson equation of state. A good fit of the data is obtained with Peng-Robinson equation of state using two adjustable parameters for carbon dioxide+1-hexene and carbon dioxide+2-ethyl-1-butene systems.