Vapor–Liquid Equilibrium and Excess Enthalpies: Measurements and Modeling for Process Industry

The purpose of this work was to examine vapor–liquid equilibria (VLE) together with excess enthalpies (HE) in order to formulate thermodynamic models for the studied systems to meet the needs of process industry. A static total pressure apparatus, a circulation still, and a headspace gas-chromatograph were used to obtain VLE data. A SETARAM C80 calorimeter with a flow mixing cell was implemented and used for HE measurements and an Anton Paar DMA 512P vibrating tube densimeter for excess volumes (VE). The parallel use of different VLE apparatuses widened the scope of the experiments and ensured the high quality of the VLE data. The studied binary systems consisted of a group of alcohols with alkanes, ethers, esters, and a ketone. Additionally, binary mixtures of ethers and nitriles were studied. The components were selected based on their relevance to chemical industry and to their potential for supporting the sustainable development of eco-friendlier chemical processes. The measured VLE data were modeled by using the Hayden–O’Connell method with the chemical theory for the vapor phase fugacities and the Wilson model, NRTL, UNIQUAC, or UNIFAC model for the liquid phase activity coefficients. The inclusion of also HE data improved the model applicability beyond the original temperature and pressure ranges. The parallel thermodynamic measurements produced data of good quality. The consistency of the data was checked by applying the area test, the point test, and the infinite dilution test on the measured data. For the static total pressure apparatus, the method of Barker was used to reduct the pTz data to pTxy data.