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In order to study the formation of carbonaceous solid deposits from fuels used in next-generation jet aircraft, we have pyrolyzed the model fuel 1-methylnaphthalene, a 2-ring aromatic component of jet fuel, at 585 • C, 110 atm, and 140 sec. The products from the reaction have been analyzed by high-pressure liquid chromatography (HPLC) with ultraviolet-visible (UV) diode-array detection in series with a mass spectrometer. Over thirty individual polycyclic aromatic hydrocarbons (PAH) have been identified from their HPLC retention times, mass spectra, and UV absorbance and/or fluorescence spectra. Of these identified products, 16 have never before been 261 262 M. L. Somers and M. J. WornatThe identification of these products is an essential step in the development of reaction schemes for the formation of PAH and ultimately carbonaceous solids in the supercritical fuel pyrolysis environment. PAH with molecular masses 402 and 426 have also been detected by the mass spectrometer, indicating the presence of 8-ring C 32 H 18 and 9-ring C 34 H 18 PAH. The identification of these 8-and 9-ring products is the subject of ongoing research.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the tane for reviewing instnictons. searching existing data sources, gathering and maintaining the data needed, and comnpleting and reviewing this coltlction of information. SPONSORING I MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR/MONITOR'S ACRONYM(S)AFOSR SUPPLEMENTARY NOTES ABSTRACTSupercritical pyrolysis experiments were conducted with three model fuels at temperatures up to 585 °C and pressures up to 110 atm. The products were analyzed by gas chromatography and high-pressure liquid chromatography with diode-array ultraviolet-visible absorbance and mass spectrometric detection, a technique ideally suited for the isomer-specific analysis of polycyclic aromatic hydrocarbons (PAH), which can serve as precursors to carbonaceous solids. Thirty-nine individual 2-to 9-ring PAH were identified in the supercritical 1-methylnaphthalene pyrolysis products-seventeen of which, for the first time.Reaction pathways involving l-naphthylmethyl, methyl, and naphthyl radicals were developed to account for the formation of the observed PAH products and explain why unobserved PAH were not formed in the supercritical I -methylnaphthalene pyrolysis environment. Likewise, reaction pathways involving benzyl, methyl, and phenyl radicals were developed that accounted for the formation of the forty-four individual PAH identified as supercritical toluene pyrolysis products and explained why unobserved PAH were not formed. The PAH product distribution from methylcyclohexane was extremely similar to that of toluene, indicating that the PAH formation mechanisms devised for toluene applied to supercritical methylcyclohexane as well.