Hydroperoxide formation and reactivity in jet fuels

Potential for Peroxide and Gum Formation in Ultra-Low-Sulfur Diesel Fuels

“…In order to meet the requirements for Ultra-Low Sulfur Diesel (ULSD) fuels with 15 ppm S or less, the sulfur is removed by hydrotreating and other processes. Since some naturally occurring sulfur compounds will decompose hydroperoxides, there are concerns that as ULSD is introduced into the fleet, that these fuels may undergo greater rates of peroxide and/or soluble gum formation during long-term storage, similar to the process that occurs in aviation fuels [1][2][3][4][5][6][7][8]. In addition, hydrotreatment can also remove other naturally occurring fuel constituents that can also function as antioxidants.…”

“…Hydroperoxides have also been shown to initiate fuel autoxidation during long-term ambient storage (storage instability), as well as short-term high-temperature stress in engine systems (thermal oxidative stability). Hydroperoxides act to greatly accelerate the rate of fuel autoxidation as well as lower the initiation temperature at which fuel degradation occurs to form soluble gums and sediments [2,4,5].…”

“…Since the early 1960's a significant amount of research effort has gone into developing test methods for predicting and measuring hydroperoxide concentrations and their effects on jet fuel stability [1][2][3][4][5]. The Navy designed a Low Pressure Reactor (LPR) test method to evaluate storage characteristics of jet fuels.…”

“…The test method effectively predicts long-term storage stability of jet fuels (24 hours predicts about 9 months of ambient) without altering the actual oxidation reaction mechanisms [1]. This and other test methods allowed researchers to study hydroperoxide formation and remediation in jet fuel [1][2][3][4][5]. These studies have led to a series of approved antioxidant formulations designed to control hydroperoxide formation in jet fuels [20].…”

Re-addition of antioxidant to aged MEROX and hydroprocessed jet fuels

“…Hydroprocessing will remove naturally occurring antioxidants including oxygen, sulfur and nitrogen heteroatoms [4]. Unstabilised fuels will tend to react with oxygen to form hydroperoxides which will affect aircraft fuel system seals, diaphragms and materials made of neoprene, nitrile rubber and Buna-N [5][6][7][8][9]. Rates of formation and decomposition of peroxides are driven by storage temperatures, duration and the availability of oxygen [10,11].…”