Autoxidation of Neat and Blended Aviation Fuels

Abstract

The liquid-phase oxidation of eight fuels and a series of 1:1 blends has been studied at elevated temperature and pressure to simulate some of the chemical-reaction conditions that cause surface fouling in aircraft fuel lines. The time, t, needed to deplete dissolved O 2 by 50% was determined for each blend and component fuel. No simple relationship was found, i.e., linking t for blends and component fuels, attesting to the complexity of aviation-fuel autoxidation. About one-half of the blends oxidize with t being intermediate between the two components. However, many blends between fuels of low thermal stability and fuels which have been severely hydrotreated are found to exhibit unusually slow oxidation, with t being greater than that measured for either component. This phenomenon is not well understood; possible explanations focus on synergistic effects among natural antioxidants, dissolved metals, and aromatics in the blends. Measurements of surface fouling in blends selected for their unusually slow oxidation indicate that thermal stability of fuels can be improved by blending with a paraffinic/cycloparaffinic solvent. Improvements in thermal stability of 1:1 blends are comparable to those achieved by introducing conventional fuel additives.

Extended Liquid-Phase Oxidation of Aviation Fuels

“…Recently we have used a dilution method as a means of estimating relative primary-antioxidant concentration (Jones and Balster, 1998). The rationale for use of this technique is that tenfold dilution of a jet fuel by a paraffinic solvent is equivalent to introducing one-tenth of the existing primary antioxidants into a paraffin.…”

The oxidative stability of synthetic fuels and fuel blends with monoaromatic blending components

“…It was expected that the naturally occurring antioxidant species in conventional fuels and the synthetic phenolic antioxidants added to hydroprocessed fuels may assist in stabilising the final blends. It has also been previously established that blending of stable and non-stable fuels may improve the final blend stability [12,13].…”

Biofuel Surrogate Oxidation: Insoluble Deposits Formation Studied by Small-Angle X-ray Scattering and Small Angle Neutron Scattering

“…Autoxidation kinetics of hydrocarbons in the liquid phase is a subject of interest over a large spectrum of human activity domains as medicine, , materials, transportation, − and the arts. , The free radical mechanism is the most accepted and studied pathway to hydrocarbons degradation, and it is the main route for many complex processes such as lipids degradation, oxidation stability of (bio)­fuels, , stability of polymers, and varnishes degradation of historical paints and instruments.…”