Identification\nof Key Molecular Features in Liquid\nPhase Autoxidation of Hydrocarbons

Sustainable aviation fuel (SAF) derived from renewable\nsources\nrepresents a promising solution to reduce aviation’s environmental\nimpact. However, its implementation currently requires blending with\nconventional fossil jet fuel, which could lead to modification of\nfuel’s initial properties. An important property of hydrocarbons\nis oxidation stability, defined as the resistance to react with oxygen\nat near-ambient temperatures. This property is of utmost importance,\nsince the accumulation of oxidation products may result in system\nfailures. In this study, we aim to understand the relationships between\nthe molecular structure and the oxidation stability of several hydrocarbons\nrelevant to the jet fuel range. For this purpose, we performed accelerated\noxidation tests of various linear and branched paraffins, naphthenes,\nolefins, aromatics, and diaromatics. Our experimental results allowed\nto identify new reactivity relationships, for instance, the impact\nof branch position in methylpentane isomers, ring size and substitutions\nin naphthenes, and olefin substitution degree on oxidation stability.\nFurthermore, our comprehensive study allowed us to correct and supplement\npreviously reported reactivity trends. For instance, we found that\nthe number of substituents in aromatic compounds reduces their stability,\nwhile ortho-substituted aromatics are more reactive than their meta-\nand para-counterparts. Interestingly, we also observed that quaternary\ncarbons can decrease the stability at higher carbon numbers and olefins\ncan present high stability when lacking allylic hydrogens.