The Effects of Temperature on the Yields of the Major Aliphatic and Aromatic Products of Supercritical n-Decane Pyrolysis

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• 作者：Subramanian V. Kalpathy ; Sean P. Bagley ; Mary J. Wornat
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2015
• 出版时间：July 22, 2015
• 年：2015
• 卷：54
• 期：28
• 页码：7014-7027
• 全文大小：1171K
• ISSN：1520-5045

文摘

To investigate the effects of pyrolysis temperature on the production of polycyclic aromatic hydrocarbons (PAH), precursors to solids, in the precombustion environment of fuels for future high-speed aircraft, we have conducted supercritical pyrolysis experiments with the model fuel n-decane, an alkane component of jet fuels. The experiments are performed in an isothermal, isobaric, silica-lined stainless-steel flow reactor at 94.6 atm, 133 s, and at six temperatures in the range of 530鈥?70 掳C, over which n-decane conversion rises from 57% to 92%. The products from the experiments have been analyzed by gas chromatography with flame-ionization and mass-spectrometric detection as well as by high-pressure liquid chromatography with diode-array ultraviolet鈥搗isible absorption and mass-spectrometric detection, and the experimentally measured product yields are reported, as functions of pyrolysis temperature, for 20 major aliphatic products (mostly C₁鈥揅₉ n-alkanes and C₂鈥揅₉ 1-alkenes), 27 one- and two-ring aromatics, and 117 PAH of three to nine aromatic rings. The yield-temperature data of 11 of the one- and two-ring aromatics and all 117 of the PAH products are each found to conform well to the first-order global-kinetic rate expression dY/dt = k_app(1 鈥?X), where Y is the measured aromatic-product yield, X is n-decane conversion, and k_app is the global first-order rate constant, k_app = A_appexp[鈭?i>E_app/(RT)]. The derived values of E_app generally increase with increasing aromatic product size from 68.26 kcal/mol for benzene, to 188.96 kcal/mol for the four-ring PAH pyrene, to 351.94 kcal/mol for the eight-ring PAH benzo[pqr]naphtho[8,1,2-bcd]perylene. In addition to all of the values of E_app and A_app determined for the individual product PAH, linear relationships for E_app and ln A_app as functions of carbon number have been determined, providing a means of modeling the production of PAH of a given carbon number in a generic way.