Thermal Decomposition Kinetics of the Thermally Stable Jet Fuels JP-7, JP-TS and JP-900

The thermal decomposition kinetics of JP-7, JP-TS and JP-900 were studied, motivated by the need of the hypersonic vehicle community for a fuel that has a high degree of thermal stability. Decomposition reactions were performed at 375, 400, 425 and 450 °C in stainless-steel ampule reactors. In all cases, the pressure before decomposition was 34.5 MPa (5000 psi). Decomposition as a function of time at each temperature was quantified by analyzing the thermally stressed liquid phase using gas chromatography. These results were used to determine global first-order rate constants that approximate the overall decomposition rate of of each fuel. For JP-7, these first-order rate constants ranged from 1.79 × 10^–5 s^–1 at 375 °C to 3.02 × 10^–4 s^–1 at 450 °C. For JP-TS, the rate constants had values between 1.74 × 10^–5 s^–1 at 375 °C to 2.70 × 10^–4 s^–1 at 450 °C. For JP-900, the rate constants ranged from 1.03 × 10^–5 s^–1 at 375 °C to 3.60 × 10^–4 s^–1 at 450 °C. At all temperatures studied, these three fuels have similar rate constants for thermal decomposition; with only one exception, the values of <i>k</i>′ are identical within the combined uncertainty. The rate constants for the decomposition of RP-2, a fuel being considered as a replacement fuel for hypersonic vehicles, are similar in the temperature range studied. Considering the time needed for 1% of the sample to decompose (<i>t</i>_0.01), we find that required instrument residence times range from 16 min at 375 °C to 30 s at 450 °C. The rate constants measured here, as well as the Arrhenius parameters that we calculate, can be used to design and plan physical property measurements at additional temperatures