Kinetics of D Atom Reactions with H2, CH4, and D2CO

Klein, Ralph; McNesby, J. R.; Scheer, Milton D.; Schoen, Louis J.

doi:10.1063/1.1729942

Cited by 27 publications

(17 citation statements)

References 8 publications

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“…Klein, McNesby, Scheer, and Schoen [22] measured k19/k18 and k20/k18 (20) From their ratio of k 19 /k 20 , from an assumption that k19/k20 = kl/k21 (21) and from Westenberg and de Haas' value [23] for reaction (21) kl was calculated.…”

Section: ( -4jmentioning

confidence: 99%

Semi-empirical extrapolation and estimation of rate constants for abstraction of H from methane by H, O, HO, and O2

Shaw¹

1978

Journal of Physical and Chemical Reference Data

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It has been concluded that for extrapolating rate constants of atom transfer reactions to and from high temperatures, a useful form of the rate constant is k=A T~exp ( -C IT), where A and C are fitted constants. For kf[cm 3 { (mol s) 1 and T{K, on the basis of previous experimental data, the values of log A and C for the following reactions are: H+CHI =H2 +CH::, log A=7.15. C=4449; O+CH!=OH+ClL, log A=6.71, C=3240; HO+CH4 =H!O+CH:, log A=6.93, C=1485 and Oz+CH~=O"H+CH .. , log A=6.93, C=26I53. At all temperatures, abstraction by HO IS faster than by O. The form of the ,rate constant is equivalent to assuming that ~Cp 0 t, the heat capacity at the constant pressure of activation, is zero. When ~CJl°:i: was estimated and assumed to be constant (in principle, a more accurate assumption than ~CpOt=O), the fit to the experimental data was slightly worse. It is confirmed that at 400 to 700 K, the kinetic and thermodynamic equilibrium constants for the reaction H +CH~=H2+CH: are significantly different. (At 1340 K, they are in agreement.) K.ey words: Estimated rate constants; hydrogen abstraction; methane combustion.

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Section: ( -4jmentioning

confidence: 99%

Semi-empirical extrapolation and estimation of rate constants for abstraction of H from methane by H, O, HO, and O2

Shaw¹

1978

Journal of Physical and Chemical Reference Data

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“…Any uncertainties in the equilibrium constant will therefore be reflected in the derived values of k,. Also, the data of Klein and co-workers (14) On fitting the theoretical data to the form…”

Section: Tunnelling Correctionsmentioning

confidence: 99%

Examination of Possible Non-Arrhenius Behavior in the reactions

Clark¹,

Dove²

1973

Can. J. Chem.

105

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“…This agreement, together with the absence of any systematic deviations, supports the proposed mechanism with Q independent of mixture composition and pressure. The high quantum yields obtained 7 ~8 in the photolysis of HCHO at temperatures above 300°C indicate that reaction (22) or (22a) competes successfully with surface destruction of the HCO radical. Early workers 8 considered the dissociation of HCO to be a first-order unimolecular process ; more recent views 16919 have favoured the second-order process (22), but no decisive experimental evidence is available.…”

Section: Discussion L N H I B I T I O N Of T H E Second Limitmentioning

confidence: 94%

“…The high quantum yields obtained 7 ~8 in the photolysis of HCHO at temperatures above 300°C indicate that reaction (22) or (22a) competes successfully with surface destruction of the HCO radical. Early workers 8 considered the dissociation of HCO to be a first-order unimolecular process ; more recent views 16919 have favoured the second-order process (22), but no decisive experimental evidence is available. The dissociation energy of HCO is still a controversial matter, arguments supporting the " high " value (25-30 kcal) and the " low " value (ca.…”

Section: Discussion L N H I B I T I O N Of T H E Second Limitmentioning

confidence: 94%

The inhibition of the hydrogen + oxygen reaction by formaldehyde

Baldwin¹,

Cowe²

1962

Trans. Faraday Soc.

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The inhibiting action of HCHO on the first and second limits of the H2+02 reaction has been studied in KClcoated vessels at 540°C. The e5ciency of inhibition is almost inversely proportional to the mole fraction of 0 2 , and is less dependent on the mole fraction of H2. This indicates that the main primary termination process is thereaction H+HCH0( 14) which competes with the reaction H+02(2); a smaller contribution results from the reaction of OH+HCHO(lS) competing with OH+H2(1), or from O+HCHO = OHSHCO(13) competing with O+H2 = OH+H(3). The efficiency of inhibition is independent of diameter showing that the HCO radicals are not destroyed at the surface ; this is confirmed by the fact that the fraction of HCO radicals undergoing chaintermination reactions is effectively independent of mixture composition and of pressure over the range 4-100 mrr~ Hg. Evidence against the reactions HCO = H+CO and HC0+02 = C02+0H is provided, and it is concluded that chain termination ultimately results either from the reaction HC0+02 = CO+HO2, or from the reaction HCO+02 = HCO3, the HCO3 radicals being destroyed at the surface. The results permit the evaluation of the ratios k14/k2 and kls/kl(or k13/k3) and from estimates of k14, a value of k2 can be obtained which agrees with earlier estimates.

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Kinetics of D Atom Reactions with H2, CH4, and D2CO

Cited by 27 publications

References 8 publications

Semi-empirical extrapolation and estimation of rate constants for abstraction of H from methane by H, O, HO, and O2

Semi-empirical extrapolation and estimation of rate constants for abstraction of H from methane by H, O, HO, and O2

Examination of Possible Non-Arrhenius Behavior in the reactions

The inhibition of the hydrogen + oxygen reaction by formaldehyde

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