Thermal Decomposition Kinetics of Jet A-1, HEFA-SAF and Jet A-1/HEFA-SAF Blends under Oxidative Atmosphere for Aeronautical Applications

Abstract

This study investigates the thermal decomposition and kinetic behavior of pure Jet A-1, hydroprocessed esters and fatty acids sustainable aviation fuel (HEFA-SAF), and their volumetric blends (50/50, 30/70, and 10/90) under oxidative conditions and heating rates (5, 10, and 15 °C/min) using thermogravimetric analysis (TGA) and model-free kinetic models in NETZSCH Neo Kinetics software. Both Jet A-1 and HEFA-SAF exhibit single-step mass loss events, but HEFA-SAF decomposes at higher temperatures (onset >160 °C, DTG_max up to 203 °C at 15 °C/min), indicating superior thermal stability. Among the blends, the Jet A-1/HEFA-SAF 10/90 blend demonstrated the highest thermal stability with the highest peak decomposition and burnout temperatures. Increasing the HEFA-SAF content reduced the mass loss rates and enhanced oxidative resistance. Kinetic modeling validated a single-step degradation mechanism across all samples. HEFA-SAF consistently showed higher activation energies (up to 93 kJ/mol), high pre-exponential factors (A = 2.95 × 10²⁰ s^–1) and stronger regression coefficient (R² = 0.998), confirming its enhanced bond strength and stability. The Friedman model proved to be the most appropriate to describe the decomposition behavior of all the samples tested due to its sensitivity to conversion-dependent reactions. This permits more precise tracking of changes in E_a in the decomposition process, particularly in thermally complex fuel systems such as Jet A-1/HEFA-SAF blends. The combined use of the KAS and Friedman models improved the interpretation accuracy. These findings underscore HEFA-SAF’s potential as a thermally stable, sustainable aviation fuel with improved combustion efficiency and long-term storage performance compared to those of conventional Jet A-1.