Enhancement of thermal oxidation stability of endothermic hydrocarbon fuels by using oxygen scavengers

Thermal oxidation stability is one of the important properties for evaluating fuel quality during the storage and use of endothermic hydrocarbon fuels; it reflects the extent to which jet fuel is affected by dissolved oxygen below 260℃ and the depth of oxidation reaction. In this work, the basic properties and thermal stability of endothermic hydrocarbon fuels with oxygen scavengers were evaluated by accelerated oxidation method combined with titration, infrared spectroscopy, particle size distribution and JFTOT. The effect of three oxygen scavengers, viz., triphenylphosphine (TPP), dicyclohexylphenylphosphine (DCP) and 1, 2, 5-trimethylpyrrole (TMP), on the auto-oxidation process of endothermic hydrocarbon fuels were comparatively investigated and the optimal addition amount within the test range was determined. The results show that there is no significant change in the fuel composition and basic physical properties after the addition of oxygen scavengers. The dissolved oxygen concentration in the fuel decreases with the increase of the amount of oxygen scavengers, and the maximum drop is 31.95 mg/m³. The peroxide value and acid value of the samples show different degrees of decline after accelerated oxidation, and the particle size distribution of the micelles tends to be smaller. The JFTOT test results can meet the national standards. In general, the addition of oxygen scavenger can effectively improve the thermal oxidation stability of the fuel; the effect of three oxygen scavengers follows the order of TMP >TPP ≈ DCP and the optimal addition amount is 1.5×10^-5 (by mass fraction).