Ozone oxidation of solid deposits produced by the thermal stressing of jet fuel

The characterization of carbon deposits produced from the thermal stressing of jet fuel by temperature programmed oxidation (TPO) of ozone oxidized samples was compared to characterization by TPO alone. A significant decrease in the amorphous deposits was formed over the nickel-sulfide crystals after oxidation using ozone. The amount of ordered carbon deposits was nearly the same before and after ozone oxidation while most of the reactive deposits were oxidized. A comparison of the TPO profiles of this sample before and after ozone oxidation showed that the latter oxidizes almost all the deposits present on the surface except leaving behind a small amount of the highly ordered species oxidizing around 780°C. Ozone oxidation removed ∼ 33 μg/sq cm of solid deposits over the surface. Any further increase in the temperature of the reaction caused decomposition of the ozone to molecular oxygen, which was undesirable. Exposure to ozone removed ∼ 90% amorphous carbon deposits at 150°C. This temperature during ozone oxidation was very low to cause any structural changes through any thermal or catalytic reactions. The presence of a high temperature CO₂ peak after removal of most of the amorphous carbon deposits from the substrate was strong evidence that the highly ordered carbon deposits on the sample surface are created during thermal stressing and not produced as an artifact during the characterization of the samples during TPO.