Doctor of Philosophy (PhD)


Chemical Engineering

Document Type



Fuels used in future high-speed jet aircraft will act as coolants to absorb excess heat produced by the engine, exposing the fuel to elevated temperatures and pressures beyond the fuel’s critical point before entering the combustion environment. Fuels used in this capacity are subject to pyrolysis reactions in the supercritical environment, forming polycyclic aromatic hydrocarbons (PAH) and eventually carbonaceous solids, a disastrous effect for aircraft operation. Thus, it is important to understand how different components of jet fuel will react in the supercritical pyrolysis environment, particularly if their reactions will lead to PAH and/or carbonaceous solids. To better understand these reactions, the model fuel 1-methylnaphthalene, an aromatic component of jet fuel, has been investigated in order to determine the supercritical pyrolysis conditions that form PAH and carbonaceous solids. Experiments have been performed at temperatures ranging from 550 to 650 °C, pressures from 50 to 110 atm, and residence times from 70 to 200 seconds in a supercritical fluid flow reactor. The products have been analyzed by high pressure liquid chromatography (HPLC) with diode-array ultraviolet-visible detection (UV) in series with mass spectrometry (MS), as well as gas chromatography with flame ionization detection and mass spectrometry. Over thirty PAH products have been identified, seventeen of which have never before been reported as products of 1-methylnaphthalene pyrolysis or combustion. A 9-ring PAH product, benzo[cd]phenanthro[1,2,3-lm]perylene, has been identified for the first time as a product of any fuel. The structures of all of the products identified from supercritical 1-methylnaphthalene pyrolysis reveal that in this environment, the two-ring aromatic unit remains intact. Reaction pathways explaining the formation of each product species and yield profiles of the products species at varying temperatures and pressures are presented. All PAH product yields were found to increase with respect to both increasing temperature and pressure, and the largest PAH exhibited dramatic increases in yields at conditions where the onset of solids formation was observed. The conversion of 1-methylnaphthalene conformed to a global first-order kinetic reaction rate, and the pressure-dependent and temperature-dependent parameters of the reaction rate have been calculated with respect to conversion of the reactant.



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Committee Chair

Mary Julia Wornat