Date of Award

5-2026

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Chemistry and Biochemistry

Thesis Sponsor/Dissertation Chair/Project Chair

Hendrik Eshuis

Committee Member

Johannes Schelvis

Committee Member

Nathanael Hirscher

Abstract

Asphaltenes are the heaviest component of crude oil consisting of a wide range of polyaromatic compounds with molar mass in the range of 500-800 g/mol. Asphaltenes tend to aggregate and form nanoclusters which lead to clogged pipelines. Understanding asphaltene aggregation has been a long-standing effort of industry and academia. Such systems are a typical example of systems studied to understand the impact of non-covalent interactions that drive the aggregation. Interactions that can be found to contribute to the stability of these aggregates can be π-π stacking, dispersion forces, and pancake stacking. A small fraction, 3%-4%, of the asphaltenes exist as long-lived radicals, which are often assumed to enhance aggregation. Asphaltene aggregation depends on the small percentage of radicals present among thousands of asphaltenes. This study aims to investigate the impact of radicals on asphaltene aggregation using computational chemistry methods. These aggregations can be modeled to consist of a radical between two asphaltenes. The size of asphaltene changes the amount of energy the aggregation has and how favorable the interactions can be. To do this, different asphaltenes are used based on the amount of carbons in the molecules. The same 10 radicals are used to compare the energies of each model. Using computational analysis, the energies of the interaction will be calculated and analyzed to gain a better understanding of naturally occurring formations. Prior research will be used as reference to understand the context of the quantified energies obtained from the calculations. Overall, as the size of the asphaltene increases, the quantified free energy becomes more negative. This indicates increasing the size of the asphaltene allows for the naturally occurring formations to be more stable than those with smaller asphaltenes. A small enhancement effect of radicals was observed, but quantification requires further study.

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