Isobaric vapor-liquid equilibria of the system [formula omitted] at 70.5 and 94.0 kPa

Abstract

Isobaric vapor-liquid equilibrium (VLE) data of ethyl acetate n- butanol were measured at 70.5 and 94.0 kPa using a modified Othmer equilibrium still. The experimental VLE data of this work, which show a positive deviation from ideal solution behavior, were analyzed using the following four group-contribution methods: the ASOG, UNIFAC, modified UNIFAC and UNIQUAC models. For the first three models, interaction parameters from the literature were utilized in the data analysis, whereas in the case of the UNIQUAC model, the optimum interaction binary parameters were obtained by regressing the experimental data using maximum likelihood principles. ASOG predicted the experimental data with the highest deviation in terms of RMSD (root-mean-square deviation) in temperature and vapor-phase mole fraction (1.12 K and 0.042 mole fraction). The modified UNIFAC correlated the experimental data with a maximum RMSD of 0.38 K and 0.015 mole fraction versus an RMSD of 0.92 K and 0.019 mole fraction given by the original UNIFAC. The best correlation was given by the UNIQUAC model (0.11 K and 0.004 mole fraction) which is expected because of the direct regression of the experimental VLE data. Activity coefficients at infinite dilution were calculated from the experimental data and compared with the prediction of the ASOG, UNIFAC, and modified UNIFAC models. The best agreement with experimental limiting activity coefficients was obtained from the modified UNIFAC model (with an absolute average deviation of 11.5%).