Application of molecular simulation to calculate miscibility of a model asphaltene molecule

The miscibility properties of a model asphaltene molecule with different solvents are studied by means of molecular simulation techniques. The pairwise interaction parameters ɛijɛij and spatial coordination numbers ZijZij, computed for the interaction between an average model asphaltene molecule (Groenzin–Mullins) with toluene by means of a Monte Carlo approach, allow to calculate mixing energies and Flory–Huggins parameters χ(T)χ(T). In particular, using regular solution theory, χ(T)χ(T) allows to calculate Hildebrand solubility parameters. The same type of analysis for asphaltene-n-alkane mixtures was, also, performed and the properties computed are consistent with experimental facts. In addition, independent calculations of the solubility parameter of the asphaltene molecule using molecular dynamics (MD) are consistent with those of the first approach and are close to the range of reported experimental values.