Kinetics of H atom attack on unsaturated hydrocarbons using spectral uncertainty propagation and minimization techniques

Sheen, David A.; Rosado-Reyes, Claudette M.; Tsang, Wing

doi:10.1016/j.proci.2012.06.062

Cited by 40 publications

(44 citation statements)

References 24 publications

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“…Tsang et al 36 have reported k(H + 135TMB → m-xylene + CH 3 ) = 6.7 × 10 13 exp(−3255/T) cm 3 mol −1 s −1 , which in turn is relative to k(H + CH 4 → CH 3 + H 2 ) = 2.4 × 10 11 exp(−7000/T) cm 3 mol −1 s −1 . In recent work, Sheen et al 37 have reanalyzed the data on the H + propene/135TMB system, 17 Kinetics of 1-Butene Decomposition. Unimolecular decomposition of 1-butene via R28 leads to allyl and methyl radicals.…”

Section: Resultsmentioning

confidence: 99%

Evaluated Kinetics of Terminal and Non-Terminal Addition of Hydrogen Atoms to 1-Alkenes: A Shock Tube Study of H + 1-Butene

Manion

Awan

2015

J. Phys. Chem. A

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Single-pulse shock tube methods have been used to thermally generate hydrogen atoms and investigate the kinetics of their addition reactions with 1-butene at temperatures of 880 to 1120 K and pressures of 145 to 245 kPa. Rate parameters for the unimolecular decomposition of 1-butene are also reported. Addition of H atoms to the π bond of 1-butene results in displacement of either methyl or ethyl depending on whether addition occurs at the terminal or nonterminal position. Postshock monitoring of the initial alkene products has been used to determine the relative and absolute reaction rates. Absolute rate constants have been derived relative to the reference reaction of displacement of methyl from 1,3,5-trimethylbenzene (135TMB). With k(H + 135TMB → m-xylene + CH3) = 6.7 × 10(13) exp(-3255/T) cm(3) mol(-1) s(-1), we find the following: k(H + 1-butene → propene + CH3) = k10 = 3.93 × 10(13) exp(-1152 K/T) cm(3) mol(-1) s(-1), [880-1120 K; 145-245 kPa]; k(H + 1-butene → ethene + C2H5) = k11 = 3.44 × 10(13) exp(-1971 K/T) cm(3) mol(-1) s(-1), [971-1120 K; 145-245 kPa]; k10/k11 = 10((0.058±0.059)) exp [(818 ± 141) K/T), 971-1120 K. Uncertainties (2σ) in the absolute rate constants are about a factor of 1.5, while the relative rate constants should be accurate to within ±15%. The displacement rate constants are shown to be very close to the high pressure limiting rate constants for addition of H, and the present measurements are the first direct determination of the branching ratio for 1-olefins at high temperatures. At 1000 K, addition to the terminal site is favored over the nonterminal position by a factor of 2.59 ± 0.39, where the uncertainty is 2σ and includes possible systematic errors. Combining the present results with evaluated data from the literature pertaining to temperatures of <440 K leads us to recommend the following: k∞(H + 1-butene → 2-butyl) = 1.05 × 10(9)T(1.40) exp(-366/T) cm(3) mol(-1) s(-1), [220-2000 K]; k∞(H + 1-butene → 1-butyl) = 9.02 × 10(8)T(1.40) exp(-1162/T) cm(3) mol(-1) s(-1) [220-2000 K]. Analogous rate constants for other unbranched 1-olefins should be very similar. Despite this, a factor of three discrepancy in the branching ratio for terminal and nonterminal addition is noted when comparing the present values with recommendations from a recent model of the important H + propene reaction. This difference is suggested to be well outside of the possible experimental errors of the present study or the expected differences with 1-butene. There thus appear to be inconsistencies in the current model for propene. In particular the addition branching ratio from that model should not be used as a reference value in extrapolations to other systems via rate rules or automated mechanism generation techniques.

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Section: Resultsmentioning

confidence: 99%

Evaluated Kinetics of Terminal and Non-Terminal Addition of Hydrogen Atoms to 1-Alkenes: A Shock Tube Study of H + 1-Butene

Manion

Awan

2015

J. Phys. Chem. A

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“…The Prior model is the jet surrogate fuel model, version 2 (JetSurF 2), 3 augmented to include formation of ethylbenzene and thermal decomposition of HME and tBPO. 23 It has 356 species and 2190 reactions. Measurements from the current experiments and from the literature that were used to constrain the model are listed in Tables 2 and 3, respectively, and will be discussed in detail later.…”

Section: Modeling Methodsmentioning

confidence: 99%

Evaluated Kinetics of the Reactions of H and CH₃ with n-Alkanes: Experiments with n-Butane and a Combustion Model Reaction Network Analysis

2015

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Presented is a combined experimental and modeling study of the kinetics of the reactions of H and CH3 with n-butane, a representative aliphatic fuel. Abstraction of H from n-alkane fuels creates alkyl radicals that rapidly decompose at high temperatures to alkenes and daughter radicals. In combustion and pyrolysis, the branching ratio for attack on primary and secondary hydrogens is a key determinant of the initial olefin and radical pool, and results propagate through the chemistry of ignition, combustion, and byproduct formation. Experiments to determine relative and absolute rate constants for attack of H and CH3 have been carried out in a shock tube between 859 and 1136 K for methyl radicals and 890 to 1146 K for H atoms. Pressures ranged from 140 to 410 kPa. Appropriate precursors are used to thermally generate H and CH3 in separate experiments under dilute and well-defined conditions. A mathematical design algorithm has been applied to select the optimum experimental conditions. In conjunction with postshock product analyses, a network analysis based on the detailed chemical kinetic combustion model JetSurf 2 has been applied. Polynomial chaos expansion techniques and Monte Carlo methods are used to analyze the data and assess uncertainties. The present results provide the first experimental measurements of the branching ratios for attack of H and CH3 on primary and secondary hydrogens at temperatures near 1000 K. Results from the literature are reviewed and combined with the present data to generate evaluated rate expressions for attack on n-butane covering 300 to 2000 K for H atoms and 400 to 2000 K for methyl radicals. Values for generic n-alkanes and related hydrocarbons are also recommended. The present experiments and network analysis further demonstrate that the C-H bond scission channels in butyl radicals are an order of magnitude less important than currently indicated by JetSurf 2. Updated rate expressions for butyl radical fragmentation reactions are provided.

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“…Assuming that the minimum and maximum values of the rate coefficients correspond to 3σ deviations Zsély et al , 2008Zádor et al 2005bZádor et al , 2006b or 2σ deviations (Sheen et al 2009(Sheen et al , 2013Sheen and Wang 2011a) from the recommended value on a logarithmic scale, the uncertainty parameter f can be converted ) at a given temperature T to the variance of the logarithm of the rate coefficient: In this case, specifying k min and k max would be insufficient.…”

Section: Sensitivity and Uncertainty Analysesmentioning

confidence: 99%

Analysis of Kinetic Reaction Mechanisms

Turányi¹,

Tomlin²

2014

202

172

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Kinetics of H atom attack on unsaturated hydrocarbons using spectral uncertainty propagation and minimization techniques

Cited by 40 publications

References 24 publications

Evaluated Kinetics of Terminal and Non-Terminal Addition of Hydrogen Atoms to 1-Alkenes: A Shock Tube Study of H + 1-Butene

Evaluated Kinetics of Terminal and Non-Terminal Addition of Hydrogen Atoms to 1-Alkenes: A Shock Tube Study of H + 1-Butene

Evaluated Kinetics of the Reactions of H and CH₃ with n-Alkanes: Experiments with n-Butane and a Combustion Model Reaction Network Analysis

Analysis of Kinetic Reaction Mechanisms

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Kinetics of H atom attack on unsaturated hydrocarbons using spectral uncertainty propagation and minimization techniques

Cited by 40 publications

References 24 publications

Evaluated Kinetics of Terminal and Non-Terminal Addition of Hydrogen Atoms to 1-Alkenes: A Shock Tube Study of H + 1-Butene

Evaluated Kinetics of Terminal and Non-Terminal Addition of Hydrogen Atoms to 1-Alkenes: A Shock Tube Study of H + 1-Butene

Evaluated Kinetics of the Reactions of H and CH3 with n-Alkanes: Experiments with n-Butane and a Combustion Model Reaction Network Analysis

Analysis of Kinetic Reaction Mechanisms

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Evaluated Kinetics of the Reactions of H and CH₃ with n-Alkanes: Experiments with n-Butane and a Combustion Model Reaction Network Analysis