Effect of Hydrotreating Severity on Jet Fuel Thermal Oxidation Stability of Olefinic Synthetic Kerosene

ABSTRACT Acid‐catalyzed oligomerization of 1‐hexene and cyclohexene was performed over H‐ZSM‐5 at 260°C and 3.5 MPa. The product was distilled to separate the olefinic kerosene (120°C–280°C). To evaluate the impact of hydrotreating severity, the kerosene was hydrotreated over reduced Ni/Al 2 O 3 , and this was repeated nine times. Each kerosene was characterized in terms of distillation profile, vapor pressure, flash point, onset of freezing, density, viscosity, refractive index, and ASTM D3241 jet fuel thermal oxidative stability test (JFTOT). The unhydrotreated kerosene failed JFTOT due to deposit thickness, which was 289 nm (≤ 85 nm required to pass). Eight of nine hydrotreated kerosenes passed the JFTOT with deposit thickness in the range 3–26 nm. Alkene conversion of 33% was sufficient for the kerosene to pass JFTOT. Although fouling species were not identified, fouling species could be converted by mild hydrotreating (160°C, 2 MPa). More severe hydrotreating had no benefit in terms of kerosene properties or thermal oxidative stability. The most severely hydrotreated kerosene resulted in a deposit thickness of only 3 nm, and most remaining alkenes comprised of species where the alkene group was situated between two tertiary carbons.