Study On The High Pressure Vapor-Liquid Equilibrium Of The Carbon Dioxide+ Acetone, +Ethyl Propanoate, +Diethyl Carbonate Systems

Accurate knowledge of phase behaviors, especially vapor-liquid equilibria (VLE) are essential in the design, development, and operation of supercritical fluid separation processes. Vapor-liquid equilibrium datas for several CO2 and various organic solvents at high pressure have been reported. High-pressure vapor-liquid phase behaviors of binary systems were measured in a cylindrical autoclave with a moveable piston and an observation window. To test the equipment and procedure, the VLE datas of system CO2+ethanol at 333K and 413K were measured. The results show a good agreement between measured datas and literature datas. This paper is a part of our research program whose purpose is to contribute to the development of the thermodynamic database of binary mixtures of CO2+acetone,+ethyl propionate, +diethyl carbonate. Vapor-liquid equilibrium datas of the CO2+acetone system was measured isothermally at 333K,353K,373K and 393K. CO2+ ethyl propionate system was measured at 313 K,333 K,353 K and 373 K. CO2+diethyl carbonate was measured at 313K,333 K,353 K,373 K,393K. The pressure range is from 2.0MPa to 15.0MPa. The mole fractions of carbon dioxide, densities and mole volumes of two phases were obtained respectively. The results show that the solubilities of CO2 in the three solvents increase drastically with pressures at the given temperature, but the contents of these solvents in gas phases increase faintly. And the solubilities decrease with temperatures at the given pressure. The critical values pc,Tc,xc and Vc of the three binary systems were estimated. Their critical curves loci exhibit the second sub of type â… . Experimental solubilities datas of the three solvents in SC CO2 were correlated with the semi empirical equation of Chrastil. The equation can describes the solubilities at high pressure fairly well.