Isobaric vapour–liquid equilibria of binary 1-propoxy-2-propanol mixtures with water and alcohols at reduced pressure

A dynamic recirculation apparatus has been used to determine the isobaric phase equilibria of binary 1-propoxy-2-propanol mixtures with water and different alcohols (methanol, ethanol, 2-butanol and 1-hexanol). The systems exhibit both positive and negative deviations from Raoult’s law. No azeotropic mixture is found in any of the systems under investigation. The binary diagram of water/1-propoxy-2-propanol (PnP) shows the well-known liquid–liquid-separation. The experimental results are correlated with the Wilson, NRTL and UNIQUAC model and also compared to the COSMO-RS predictive model and the modified UNIFAC group-contribution method. Additionally, the vapour pressure of PnP has been determined experimentally up to 140 ° C as prerequisite for modelling of the data.