On the mechanisms of PAH and solid formation during thermal degradation of jet fuels

Deposit formation during fuel degradation in a low temperature regime (<300°C) has been generally attributed to autoxidation, but pyrolysis predominates at high temperature. Much previous work has been done at low temperatures, but the future high-performance jet aircraft requires jet fuels thermally stable at high temperatures. There is little information on the mechanisms of solid formation from jet fuels and relevant hydrocarbons. In this paper, the authors focus on the mechanistic aspects of pyrolytic fuel degradation in terms of the formation of polycyclic aromatic hydrocarbons (PAH) and solid deposits. To develop a fundamental understanding, we examined the fuel degradation chemistry by using a number of model compounds. Based on the spectroscopic analyses of liquid and solid products from jet fuels and model compounds, the possible mechanisms for PAH and solid formation are proposed.