Modeling the thermodynamic properties and phase behaviour of organic sulfur molecules with a group contribution based statistical associating fluid theory approach (GC-SAFT-VR)

Leveraging the demonstrated accuracy of the group contribution statistical associating fluid theory for potentials of variable range (GC-SAFT-VR) equation of state to predict the phase equilibrium and thermodynamic properties of fluids, we use this approach to study organic sulfur molecules and their mixtures. Knowledge of the phase equilibria and thermodynamic properties of sulfur containing compounds, while of interest in a number of fields, is important to the development of petroleum products with lower sulfur content. In this work the CH(thiophene) and -S- functional groups are characterized by fitting to experimental data for pure thiophene and cross interactions determined in order to extend the GC-SAFT-VR equation of state to the study of organic sulfur molecules. Theoretical predictions are compared with experimental results for the phase behavior of 3-methylthiophene, 2-methylthiophene, and benzothiophene, as well as their binary mixtures with alkanes, alkenes, aromatics, carbon dioxide, and alcohols. As far as we are aware, this work is the first SAFT-based study of mixtures containing thiophene molecules with aromatics, alcohols, and hydrocarbon molecules. The GC-SAFT-VR approach is found to accurately predict the phase behavior of the sulfur organic compounds studied, providing a method to determine the phase behavior of these compounds without heavy reliance on experimental data.