Effect of phenolic antioxidants on the thermal oxidation stability of high-energy–density fuel

The addition of antioxidants is normally adopted to improve the thermal oxidation stability of jet fuel, but the detailed antioxidation mechanism is still ambiguous. Herein, the inhibition of exo-tetrahydrodicyclopentadiene (the main component of JP-10) toward thermal oxidation and deposition by phenolic antioxidants (2,6-di-tert-butyl-4-methyphenol (BHT), 6-tert-butyl-2,4-dimethyphenol (TBDP), 2,6-di-tert-butylphenol (DTBP), 2-tert-butyl-4-methoxyphenol (BHA) and 2-tert-butyl-4-methylphenol (TBMP)) was investigated to reveal antioxidation mechanism and screen the best antioxidant for high-energy–density fuel. The theoretical and experimental results show that the addition of all phenolic antioxidants can significantly inhibit fuel oxidation and prolong the shelf life. Importantly, TBDP and TBMP show better performance than other antioxidants since they can scavenge more radicals per antioxidant molecule. However, antioxidants form dimer products via the addition between phenoxyl radicals and alkyl radicals during short-term thermal stress, which has a higher tendency to produce deposits. Consequently, the addition of phenolic antioxidants causes more severe deposition when jet fuel serves as the coolant in aircrafts. This work would guide the rational design of antioxidant for practical application in high-energy–density fuel.