Thermal Stability Study of Ras Lanuf Jet Fuel by NMR-Spectroscopy and Gas Chromatography Mass Spectrometry

The thermal stability of jet fuel produced by Ras Lanuf refinery was studied by nuclear magnetic resonance-spectroscopy (n.m.r.) and gas chromatography-mass spectrometry (g.c.-m.s.). The fuel was thermally stressed for 3 hours at different temperatures: 360, 380, 400, 420, and 440 °C. The vol% of aromatics, olefins, and paraffins was calculated by proton n.m.r. spectroscopy. The buildup of olefinic compounds started at 380 °C. GC analysis indicated that the formation of olefins and aromatics at high temperatures was accompanied by a decrease in C₁₁ and C₁₂ aliphatic fractions. Rapid increases in aromatic contents were observed at high temperatures (420-440 °C). Identification of the newly formed compounds was carried out by g.c.-m.s. The formation of solid Carbonaceous deposits were first observed at 420 °C. Its content reached 19.5 wt% at 440 °C.