Phase equilibria of three binary systems containing 2,5-dimethylthiophene and 2-ethylthiophene in hydrocarbons

• Phase equilibria on three binary systems containing 2,5-dimethylthiophene and 2-ethylthiophene in hydrocarbons was measured with a circulating still.
• Verify the consistency of the experimental data.
• The binary systems exhibited positive deviation from ideal system and no azeotropic behavior was found.
• The VLE data were correlated well by the activity coefficient models.

Isobaric vapor–liquid equilibrium (VLE) data for binary systems 2-ethylthiophene + n-decane, 2,5-dimethylthiophene + n-decane and 2-ethylthiophene + mesitylene were measured at 101.33 kPa using the modified Rose–Williams equilibrium still. Gas chromatography was used to analyze compositions of the samples from the vapor–liquid equilibrium system. Thermodynamic consistency of the experimental data were checked both with the Herington consistency test and point-to-point test of Van Ness, which ensure the reliability of experimental data. The experimental data were correlated by the Wilson and non-random two-liquid (NRTL) activity coefficient models and were compared with original UNIFAC predictive model. The corresponding parameters for the Wilson and NRTL models were obtained. The results show that the calculated values of the vapor-phase mole fraction and bubble point temperature by Wilson, NRTL and UNIFAC models agree well with the experimental data.