Identification of Five- to Seven-Ring Polycyclic Aromatic Hydrocarbons from the Supercritical Pyrolysis of n-Decane

In order to study the formation of carbonaceous solid deposits from aviation fuels in the pre-combustion environment of next-generation high-speed aircraft, we have pyrolyzed the model fuel n-decane (critical temperature, 344.5 °C; critical pressure, 20.7 atm), an alkane component of jet fuel, under supercritical conditions at 570 °C, 100 atm, and 133 sec. The product polycyclic aromatic hydrocarbons (PAH), precursors to the solid deposits, have been analyzed by a two-dimensional high-pressure liquid chromatographic separation technique with ultraviolet-visible absorbance and mass spectrometric detection. The analyses reveal that there are 24 unsubstituted PAH products with molecular weights between 252 and 300. Of these, 12 are benzenoid: benzo[a]pyrene, benzo[e]pyrene, perylene, benzo[ghi]perylene, anthanthrene, benzo[b]chrysene, dibenz[a,c]anthracene, dibenz[a,h]anthracene, dibenz[a,j]anthracene, pentaphene, picene, and coronene; two are methylene-bridged derivatives of two of the benzenoid PAH: 11H-in...