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n-Butanol pyrolysis in a flow reactor was investigated at the pressures of 5, 30, 80, 200, and 760 Torr. Synchrotron vacuum ultraviolet photoionization mass spectrometry was used for the identification of pyrolysis species and the measurement of their mole fractions. A detailed kinetic model consisting of 121 species and 658 reactions was developed to simulate the n-butanol pyrolysis. To enhance the accuracy of the model, the rate constants of unimolecular reactions of n-butanol and β-scission reactions of four n-butanol radicals (C4H8OH) were calculated with the variable reaction coordinate–transition-state theory (VRC–TST) and the Rice–Ramsperger–Kassel–Marcus (RRKM) theory coupled with the master equation method. These rates are very sensitive to the mole fractions of pyrolysis species and have been well-validated by the pyrolysis experiment. The model was further validated by the low-pressure premixed flames at different equivalence ratios, oxidation data from the jet-stirred reactor, and ignition delay times. The comparison between predicted and measured results exhibited a good performance of this model. The reaction product analysis and sensitivity analysis were performed to elucidate the chemistry under different conditions.

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a b s t r a c tThe pyrolysis of cyclohexane at low pressure (40 mbar) was studied in a plug flow reactor from 950 to 1520 K by synchrotron VUV photoionization mass spectrometry. More than 30 species were identified by measurement of photoionization efficiency (PIE) spectra, including some radicals like methyl, propargyl, allyl and cyclopentadienyl radicals, and stable products (e.g., 1-hexene, benzene and some aromatics). Among all the products, 1-hexene is formed at the lowest temperature, indicating that the isomerization of cyclohexane to 1-hexene is the dominant initial decomposition channel under the condition of our experiment. We built a kinetic model including 148 species and 557 reactions to simulate the experimental results. The model satisfactorily reproduced the mole fraction profiles of most pyrolysis products. The rate of production (ROP) analysis at 1360 and 1520 K shows that cyclohexane is consumed mainly through two reaction sequences: cyclohexane ? 1-hexene ? allyl radical + n-propyl radical, and cyclohexane ? cyclohexyl radical ? hex-5-en-1-yl radical that further decomposes to 1,3-butadiene via hex-1-en-3-yl and but-3-en-1-yl radicals.

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