Studies in Vapour-Liquid Equilibria

Abstract

A programme of practical work, involving both the determination of vapour-liquid equilibrium data for acetic acid systems, and theoretical work, including the development of data reduction programs, has been carried out. The practical work involved modification of the feed and pressure systems of a modified Cathala still and its subsequent testing on the system Ethyl Acetate - n-Butanol at 760 mmHg. The modifications proved successful and the modified Cathala still was further used to obtain data on Acetic Acid-Methanol, Acetic Acid-Ethanol, Acetic Acid-n-Butanol, all at 760 mmHg. This still was also run isothermally for the first time to obtain data for the system Acetic Acid -Butanol at 119°C. The practical work also included the development of a new equilibrium still based on that of Raal Code and Best, the new still being tested on the system Acetic Acid-Water at 760 mmHg, 69.7 °C, 79.9 C and 89.9 C. Consistency testing of all of the experimental data, using a Barker type method, indicated a high level of consistency for all of the systems. A new programming approach was used in producing new versions of the data reduction computer program developed by Gibson-Robinson., The highly structured form of the new versions enabled the programs to be more flexible and thus both the addition of new liquid phase models and "debugging" have been made easier. An additional vapour pressure equation, the Harlacher equation, was introduced into the data reduction program to investigate whether its use improved data-fitting. This equation was compared with the equation already in use, a modified Antoine equation, by running the program on several Acetic Acid systems. No distinct improvement was detected by use.of the new equation.