Mechanistic insights into the thermal oxidative deposition of C10 hydrocarbon fuels

Thermal oxidation stability is a key issue for jet fuel when serving as a coolant in aircraft. However, the deposition propensity and mechanism of hydrocarbons with different molecule structures remain ambiguous. In this study, the oxidation stability and deposition propensity of C10 hydrocarbon fuels, i.e. , tetralin, cis- / trans- decalin, exo -tetrahydrodicyclopentadiene ( exo- THDCPD), and n- decane, were determined. The oxidation stability of hydrocarbons follows the order of n- decane >  exo- THDCPD >  trans- decalin >  cis- decalin > tetralin, which is highly associated with the molecular-structure-dependent C–H bond dissociation enthalpy. Differently, the deposition propensity follows the order of trans- decalin >  exo- THDCPD >  n- decane >  cis- decalin > tetralin, which can be associated with the stability of oxidation intermediates, especially the hydroperoxides. The more stable the intermediates are, the fewer deposits will be produced. These results demonstrate the relationship between thermal oxidation stability and hydrocarbon molecular structure, which is helpful for a better understanding of jet fuel deposition mechanism.