Shock Wave Study on the Thermal Unimolecular Decomposition of Allyl Radicals

Fernandes, Ravi X.; Giri, Binod Raj; Hippler, H.; Kachiani, Chatuna; Striebel, Frank

doi:10.1021/jp047482b

Cited by 43 publications

(64 citation statements)

References 28 publications

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“…Figure 6 also demonstrates that the reaction model in Table I is able to reproduce the measured formation of H-atoms. The derived Arrhenius expression for 1-hexene dissociation (R2) and the used rate coefficient values concerning the allyl dissociation (R4) and the bimolecular reaction (R8) in the context of our experiments go well with the results of other experimental and theoretical investigations on these reactions [7,11,[28][29][30]. Because of the limited resolution of our experiments, we are not able to make a clear statement which of the literature rate coefficients for reaction (R2), given by Tsang [7] and Kiefer 11], will fit better to our experiments.…”

Section: -Hexene Experimentssupporting

confidence: 81%

“…Concerning the dissociation of allyl radicals to allene and H-atoms, which was identified as the major source for H-atoms, several expressions for k(T ) are published in literature [25][26][27][28]. The result of the kinetic modeling of our 1-hexene experiments strongly depends on the chosen Arrhenius expression for the allyl dissociation.…”

Section: -Hexene Experimentsmentioning

confidence: 99%

“…The result of the kinetic modeling of our 1-hexene experiments strongly depends on the chosen Arrhenius expression for the allyl dissociation. Fernandes et al [28] investigated the thermal decomposition of allyl radicals by shock tube experiments coupled with H-ARAS as detection method. They performed a series of experiments for pressures around 0.25, 1, and 4 bar for Ar and N 2 as bath gases.…”

Section: -Hexene Experimentsmentioning

confidence: 99%

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Formation of H‐atoms in the pyrolysis of cyclohexane and 1‐hexene: A shock tube and modeling study

Peukert

Naumann

Braun‐Unkhoff

et al. 2010

Int J of Chemical Kinetics

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Cyclohexane (cC 6 H 12 ) plays an important role in the combustion of practical liquid fuels, as a major component of naphthenic compounds. Therefore, the pyrolysis of cyclohexane was investigated by measuring the formation of H-atoms. The thermal decomposition of 1-hexene (1-C 6 H 12 ) was also studied, because of the assumption that 1-hexene is the sole initial product of cyclohexane decomposition. For cyclohexane, the measurements were performed over a temperature range of 1320-1550 K, at pressures ranging from 1.8 to 2.2 bar; 1-hexene experiments were done at temperatures between 1250 and 1380 K and pressures between 1.5 and 2.5 bar. For each experiment, the time-dependent formation of H-atoms was measured behind reflected shock waves by using the method of atomic resonance absorption spectrometry. For the dissociation of 1-hexene to n-propyl (C 3 H 7 ) and allyl (C 3 H 5 ) radicals, the following Arrhenius expression was derived: k R2 (T ) = 2.3 × 10 16 exp(−36,672 K/T ) s −1 . For cyclohexane, overall rate coefficients (k ov ) were deduced for the global reaction cC 6 H 12 → products + H from the H-atom time profiles; the following temperature dependency was obtained: k ov (T ) = 4.7 × 10 16 exp(−44,481 K/T ) s −1 . For both sets of rate coefficient values, an uncertainty of ±30% is estimated. Especially concerning the isomerization cC 6 H 12 → 1-C 6 H 12 , our experimental results are in excellent agreement with the rate coefficient values given by Tsang (Tsang, W. Int J Chem Kinet 1978Kinet , 10, 1119Kinet -1138. A reaction model was assembled that is able to reproduce the H-atom profiles measured for both sets of experiments. According to this model, H-atoms are mostly stemming from the thermal decomposition of allyl radicals (C 3 H 5 ), which arise from the decomposition of 1-hexene. Furthermore, it will be shown that the recombination of allyl radicals with H-atoms to propene (C 3 H 6 ) also represents a very important subsequent reaction.

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Section: -Hexene Experimentssupporting

confidence: 81%

Section: -Hexene Experimentsmentioning

confidence: 99%

Section: -Hexene Experimentsmentioning

confidence: 99%

See 1 more Smart Citation

Formation of H‐atoms in the pyrolysis of cyclohexane and 1‐hexene: A shock tube and modeling study

Peukert

Naumann

Braun‐Unkhoff

et al. 2010

Int J of Chemical Kinetics

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“…Our setup consists of a microwave discharge lamp, a VUV monochromator, and a solarblind photomultiplier connected to a storage oscilloscope. Details of the optical setup and the calibration procedure can also be found in [10,11]. The H-ARAS method provides very high sensitivity for H-atom detection so that concentrations in the range between 5×10 -13 and 1×10 -10 mol/cm 3 can easily be detected.…”

Section: Methodsmentioning

confidence: 99%

Kinetic investigations of the unimolecular decomposition of dimethylether behind shock waves

Fernandes

Fittschen

Hippler

2009

React Kinet Catal Lett

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“…The experimental setup has been described previously, [27][28][29] and only a brief summary is given here.…”

Section: Methodsmentioning

confidence: 99%

Shock-Tube Study of the Thermal Decomposition of CH₃CHO and CH₃CHO + H Reaction

2008

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The thermal decomposition of acetaldehyde, CH3CHO + M --> CH3 + HCO + M (eq 1), and the reaction CH3CHO + H --> products (eq 6) have been studied behind reflected shock waves with argon as the bath gas and using H-atom resonance absorption spectrometry as the detection technique. To suppress consecutive bimolecular reactions, the initial concentrations were kept low (approximately 10(13) cm(-3)). Reaction was investigated at temperatures ranging from 1250 to 1650 K at pressures between 1 and 5 bar. The rate coefficients were determined from the initial slope of the hydrogen profile via k1 = [CH3CHO]0(-1) x d[H]/dt, and the temperature dependences observed can be expressed by the following Arrhenius equations: k1(T, 1.4 bar) = 2.9 x 10(14) exp(-38 120 K/T) s(-1), k1(T, 2.9 bar) = 2.8 x 10(14) exp(-37 170 K/T) s(-1), and k1(T, 4.5 bar) = 1.1 x 10(14) exp(-35 150 K/T) s(-1). Reaction was studied with C2H5I as the H-atom precursor under pseudo-first-order conditions with respect to CH3CHO in the temperature range 1040-1240 K at a pressure of 1.4 bar. For the temperature dependence of the rate coefficient the following Arrhenius equation was obtained: k6(T) = 2.6 x 10(-10) exp(-3470 K/T) cm(3) s(-1). Combining our results with low-temperature data published by other authors, we recommend the following expression for the temperature range 300-2000 K: k6(T) = 6.6 x 10(-18) (T/K) (2.15) exp(-800 K/T) cm(3) s(-1). The uncertainties of the rate coefficients k1 and k6 were estimated to be +/-30%.

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Shock Wave Study on the Thermal Unimolecular Decomposition of Allyl Radicals

Cited by 43 publications

References 28 publications

Formation of H‐atoms in the pyrolysis of cyclohexane and 1‐hexene: A shock tube and modeling study

Formation of H‐atoms in the pyrolysis of cyclohexane and 1‐hexene: A shock tube and modeling study

Kinetic investigations of the unimolecular decomposition of dimethylether behind shock waves

Shock-Tube Study of the Thermal Decomposition of CH₃CHO and CH₃CHO + H Reaction

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Shock Wave Study on the Thermal Unimolecular Decomposition of Allyl Radicals

Cited by 43 publications

References 28 publications

Formation of H‐atoms in the pyrolysis of cyclohexane and 1‐hexene: A shock tube and modeling study

Formation of H‐atoms in the pyrolysis of cyclohexane and 1‐hexene: A shock tube and modeling study

Kinetic investigations of the unimolecular decomposition of dimethylether behind shock waves

Shock-Tube Study of the Thermal Decomposition of CH3CHO and CH3CHO + H Reaction

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Shock-Tube Study of the Thermal Decomposition of CH₃CHO and CH₃CHO + H Reaction