Phase equilibria on five binary systems containing 1-butanethiol and 3-methylthiophene in hydrocarbons

Abstract

Isothermal vapor–liquid equilibrium (VLE) of the following systems was measured with a recirculation still: 1-butanethiol + methylcyclopentane at 343.15 K, 1-butanethiol + 2,2,4-trimethylpentane at 368.15 K, 3-methylthiophene + toluene at 383.15 K, 3-methylthiophene + o-xylene at 383.15 K, and 3-methylthiophene + 1,2,4-trimethylbenzene at 383.15 K. 1-Butanethiol + methylcyclopentane and 1-butanethiol + 2,2,4-trimethylpentane systems exhibit positive deviation from Raoult's law, whereas systems containing 3-methylthiophene in aromatic hydrocarbons exhibit only slight positive deviation from Raoult's law. A maximum pressure azeotrope was found in the system 1-butanethiol + 2,2,4-trimethylpentane ( x 1 = 0.548, P = 100.65 kPa, T = 368.15 K). The experimental results were correlated with the Wilson model and compared with original UNIFAC and COSMO-SAC predictive models. Raoult's law can be used to describe the behavior of 3-methylthiophene in aromatic hydrocarbons at the experimental conditions in this work. Liquid and vapor-phase composition were determined with gas chromatography. All measured data sets passed the thermodynamic consistency tests applied. The activity coefficients at infinite dilution are also presented.