Asphaltene aggregation under the influence of structural features and interaction energies: Combination of quantum mechanical and molecular dynamics approaches

Abstract

The importance of the model to predict the aggregation behavior of asphaltene molecules at the molecular level was well established in different studies. Elucidation of the relationship between the interaction energy and the structural characteristics of asphaltene molecules to their aggregation behavior still needs further investigation. For this purpose, we combined the quantum mechanics and molecular dynamics approaches and analyzed the interaction energy of asphaltene to find out the effect of structural features on the aggregation behavior. The interaction energy of asphaltene is used in this study to evaluate the potential of aggregation. We found that asphaltene molecules with smaller aromatic cores and shorter side chains form longer but more unstable stacks in the aggregation phase. If these structures do not have polar groups in the side chains, they will not show significant aggregation behavior in the clustering phase. Also, the length of stacks formed in the accumulation phase can be interpreted and predicted based on the terms such as attractive dispersion energy and steric repulsion in the interaction energy of asphaltene dimers. The aggregation process is explained by analyzing the nature of the interaction energy. As a result, by examining the effect of structural features on interaction energy, a relatively acceptable picture of the aggregation behavior of the asphaltene molecules can be obtained.