On the Mechanisms of Formation of Thermal Oxidative Deposits in Jet Fuels. Are Unified Mechanisms Possible for Both Storage and Thermal Oxidative Deposit Formation for Middle Distillate Fuels?

Abstract

This paper attempts to expand mechanistic understanding of the fundamental chemistry involved in jet fuel thermal oxidative deposit formation. The proposed mechanisms are a synthesis of ideas and results from the fuel community at large; a few new experiments are also reported. In addition, it is suggested that the available literature is consistent with similar chemistry for deposit formation for both storage and thermal oxidative degradation for middle distillates in general.

The Effects of Storage on Turbine Engine Fuels

“…One possible mechanism that leads to the formation of high molecular weight products involves the oxidation of hydrogen containing heteroatomic aromatic compounds to form electrophilic quinone-like species. The quinone-like species reacts with nucleophile present in the fuels to eventually form soluble macromolecular oxidatively reactive species (SMORS) [16]. The initial step of the SMORS mechanism is the reaction of phenol with a peroxy radical to abstract a hydrogen atom.…”

The Instability of Storage of Middle Distillate Fuels: A Review

“…The studies of (Worstell et al, 1981) revealed that heterocyclic nitrogenous compounds in conjunction with polar fuel components promote the formation of sediment in diesel and jet fuels by base catalysis under conditions of accelerated storage. An attempt has been made by Beaver et al (2005) to expand the mechanistic understanding of the fundamental chemistry involved in jet fuel thermal oxidative deposit formation. Wechter and Hardy (1996) reported that fuel sediments are composed of sulfonic acids, which are formed by the oxidation of aromatic thiols and basic condensate arising from the action of oxygen and acids on pyrroles and indoles.…”

Jet Fuel

“…However, this beneficial effect is dependent on the amount of prestressing. Phenol (not hindered alkyl phenols) has been implicated in the formation of deposits during thermal stability testing, and a mechanism involving phenol oxidation was proposed [20] that described the observations with various crude oil and Fischer-Tropsch semisynthetic jet fuel mixtures reasonably well [18]. Phenol (not hindered alkyl phenols) has been implicated in the formation of deposits during thermal stability testing, and a mechanism involving phenol oxidation was proposed [20] that described the observations with various crude oil and Fischer-Tropsch semisynthetic jet fuel mixtures reasonably well [18].…”