Prediction of the phase equilibria for island-type asphaltenes via HMC-WL simulations.

Recent force microscopy experiments have shed light on new possible molecular structures for asphaltenes, which are key compounds for the oil industry. These studies have revealed the significance of asphaltenes with an island molecular architecture, i.e., composed of a large polycyclic aromatic hydrocarbon (PAH) core and alkyl side chains. In this work, we carry out molecular simulations based on a Wang-Landau sampling of the isothermal-isobaric ensemble to determine the thermodynamic properties of island-type asphaltenes at the vapor-liquid coexistence. We first parameterize a coarse-grained force field for these systems, focusing on compounds with a PAH core containing fluorene, fluoranthene, and dibenzothiophene motifs. Then, using this coarse-grained force field, we predict the entire phase envelope, including the boiling points and the critical parameters for a series of island-type asphaltenes.