Mechanistic investigation into the formation of insolubles in bulk fuel jet fuel using quantum chemical and experimental techniques. (15th February 2023) - Adams, Charlie
Abstract: The SMORS mechanism describing the formation of insoluble material in bulk jet fuel was investigated using density functional and experimental techniques. The first part of the SMORS mechanism, the formation of quinones from the oxidation of indigenous fuel phenols, was shown to proceed via two possible pathways. First, a single-step pathway yielding two quinones and a hydrogen peroxide. Secondly, a two-step pathway yielding a quinone, p-chinole and singlet oxygen. The second step of the SMORS mechanism, the reaction of quinones with electron-rich heterocycles in fuels, was shown to proceed via a homolytic aromatic substitution pathway. These findings, allow us to propose a modified SMORS mechanism, built on our enhanced mechanistic understanding of fuel deposit formation. Highlights: Nitrogen and phenolic compounds are oxidized in a multi-step process form insolubles in jet fuel. Phenols oxidize via two potential pathways to quinones in fuels. The originally proposed electrophilic aromatic substitution mechanism for the coupling between quinones and electron-rich nitrogen heterocycles in fuels was shown to be prohibited. Quinones and electron-rich nitrogen heterocycles instead couple via a homolytic aromatic substitution pathway.