Aromatisation process as part of bitumen ageing in the light of electronic structure and further oxidation of its components
Szymon Malinowski
Abstract
Research on the aging process of bitumen has been very intensive in recent years. However, they mainly involve the study of its components oxidation process using experimental methods. Therefore, the main objective of this work was to study the aromatization process using the Density Functional Theory (DFT) method. The use of this method allowed to determine the energetics of a aromatization reactions that can occur in bitumen due to both UV radiation and thermal ageing. In addition, the paper explored how the aromatization process affects the polarity of bitumen components, their electrostatic interactions with atmospheric O2 molecules and further oxidative aging. Quantum-chemical calculations indicated that energetically the aromatization reactions of asphaltenes are the most favourable. In addition, aromatization of the hopane molecule leads to the highest increase in electrostatic interactions with atmospheric oxygen molecules and to the greatest degree enhances its oxidation both by radical reactions and formation of the –COOH transition product.