Analytical pyrolysis of jet fuel using different free radical initiators to produce low molecular weight hydrocarbons

Abstract

Employing endothermic hydrocarbon fuels in high speed flights aids in regenerative cooling of the aircraft surfaces and components due to the physical and chemical heat sink mechanisms they offer. The development of such fuels involves a thorough understanding of its pyrolysis characteristics in the presence of additives. In this study, analytical Curie point pyrolyzer is used to conduct pyrolysis of Jet-A1 fuel, and investigate the effect of temperature and free radical initiators on the pyrolysate composition. The temperatures were 590 °C, 740 °C and 920 °C, and the initiators were triethylamine (TEA), 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), phenyl hydrazine (PH), 1-nitropropane (NP), di-tert-butyl peroxide (DTBP), and cumene hydroperoxide (CH). The results showed that, at 590 °C, the addition of TEMPO, NP and PH, all at 5 wt% to the fuel, improved the cracking reactions with 25% decline in yield of alkanes compared to pyrolysis of neat Jet-A1. It was also observed that the yield of alkyl-substituted benzenes was high in presence of TEMPO and PH, while the yield of iso-alkanes was high in the presence of DTBP, CH and TEA. At 920 °C, the yield of low molecular weight alkenes (C3-C7) was high with TEMPO (11.6%) followed by PH (6.8 wt%), TEA (6.7 wt%) and NP (6.5 wt%). The plausible reactions occurring in the presence of initiators are discussed by thoroughly analyzing the pyrolysates.