Ozone–Persulfate Coupled Oxidation Mechanism of Asphaltene and Resin in Heavy Petroleum Components Based on Reactive Force Field Potential

Abstract

Asphaltene and resin are the most structurally complex and recalcitrant compounds in petroleum, causing them to form persistent pollutants when they enter the environment. In this study, the degradation mechanisms of asphaltene and resin in heavy petroleum components under ozone–persulfate coupled oxidation systems were investigated using reactive force field molecular dynamics simulations. The oxidation process consisted of a rapid reaction phase and a slow reaction phase, wherein components with a higher molecular weight and more ring structures exhibited faster radical consumption rates. The coupled oxidation system demonstrated superior efficiency compared to single-oxidant systems. Hydroxyl radicals demonstrated superior degradation efficiency for macromolecules compared to sulfate radicals. Asphaltene degradation primarily involved the sequential cleavage of side chains around condensed rings, followed by ring-opening and reorganization. Resin degradation preferentially targeted alkyl chains and heterocycles, among which sulfur-containing heterocycles were more readily degraded than oxygen-containing structures. This study provides the reaction network of heavy petroleum components under coupled oxidation, as well as a theoretical foundation for remediating petroleum-contaminated soils.