Polymers for asphaltene dispersion: Interaction mechanisms and molecular design considerations

The prevention of asphaltene self-assembly is a technical challenge of broad scope since asphaltene aggregates can precipitate and cause fouling in production facilities, pipelines and refineries. Although polymeric dispersants are often used as flow improvers and offer great promise for affordable and effective prevention of deposition, the mechanism by which they affect aggregation is relatively understudied. In order to clarify the nature of interactions between polymers and asphaltenes in aliphatic solvents, systematic molecular dynamics simulations were employed to test several organic polymer structures that were reported to be effective in previous experimental studies. Bulk phase simulations with model asphaltenes with different functional groups revealed that several particular structural attributes are effective for maintaining asphaltene dispersity while preventing full aggregation. A specific polymer was determined to be most effective due to its unique capability to occupy the active stacking sites of asphaltene aggregates (i.e. aromatic cores), thereby preventing further n-n stacking of asphaltenes. In addition, the favored polymer was shown to possess superior solubility in aliphatic solvents and exhibit less chain collapse when compared to the other structures tested. Several suggestions are presented to provide insight to the design of more effective polymeric flow improvers. (C) 2017 Elsevier B.V. All rights reserved.