Vapor-liquid equilibria for mixtures of ethylene glycol, propylene glycol, and water between 98° and 122°C

Catalytic hydrocracking of sorbitol constitutes an interesting possibility of using excess production of cereals. Such reaction leads to an aqueous solution of ethylene and propylene glycol, butanediols, glycerol, alcohols, which is then to be distilled with the aim of separating the different species present. Since few equilibrium data have been published for this kind of mixtures, the first part of the present work was aimed at producing isothermal vapor-liquid equilibrium data in the range of 98°–122°C for the three binary solutions which can be obtained from water, ethylene glycol and propylene glycol. Afterwards, the equilibrium data were correlated by means of the UNIQUAC model, and the binary interaction parameters were evaluated. Eventually, the equilibrium conditions for the ternary mixture ethylene glycol-propylene glycol-water were experimentally determined, and it was shown that the UNIQUAC model is capable of estimating with very good accuracy the equilibrium conditions for such mixture.