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Issue 22, 2000
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Laser powered homogeneous pyrolysis of butane initiated by methyl radicals in a quasi-wall-free reactor at 750–1000 K

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The pyrolysis of n-butane, initiated by methyl radicals has been studied in the temperature range 750–1000 K and at pressures 0.08–0.13 bar in a quasi-wall-free reactor using laser heating by fast vibrational–translational (V–T) energy transfer. This is a convenient method to study homogeneous high-temperature kinetics since the reactor walls remain cold. The radial temperature distribution in the reactor has been investigated by four different methods: stationary heat balance, optical absorption, pressure rise, and the temperature dependence of the rate of an isomerization reaction. Methyl radicals were produced [italic v (to differentiate from Times ital nu)]ia the fast thermal dissociation of di-tert-butyl peroxide and product analysis was performed by the use of GC-MS. The main products of the overall reaction of the model system (n-C4H10 + CH3) were C2H4, C3H6, C3H8, whereas 1-C4H8, n-C5H12, iso-C5H12 were minor components, all showing a strong dependence on temperature. The product distribution and the temperature dependence were analyzed by a kinetic model of 61 species and 164 reactions developed for the high-temperature butane and the low-temperature n-pentane oxidation. Good agreement was found between our experimental investigations and the modeling. However, we had to slightly adjust the rate constants for the reactions

At a temperature of 1000 K we found a larger branching ratio of k3/(k3 + k4) = 1/3 compared to 1/8 as extrapolated from low-temperature data. The total rate coefficient was found to be (k3 + k4) = 8 × 109 cm3 mol−1 s−1 which is about 50% higher than the extrapolated values.

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Article information

29 Jun 2000
14 Sep 2000
First published
18 Oct 2000

Phys. Chem. Chem. Phys., 2000,2, 5127-5132
Article type

Laser powered homogeneous pyrolysis of butane initiated by methyl radicals in a quasi-wall-free reactor at 750–1000 K

E. Goos, H. Hippler, K. Hoyermann and B. Jürges, Phys. Chem. Chem. Phys., 2000, 2, 5127
DOI: 10.1039/B005219L

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