A kinetic study about the reactions of NH(X<sup>3</sup>Σ<sup>−</sup>) with hydrocarbons part 1: Saturated hydrocarbons and acetaldehyde

Röhrig, Michael; Wagner, H. Gg.

doi:10.1002/bbpc.19940980615

Cited by 28 publications

(12 citation statements)

References 20 publications

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“…In order to check the compatibility of the recommended enthalpies of formation by Anderson, &@ K ( N H~) = 192 and A& K(NH) = 357 kJ mol-' were used in this calculation. The result in apparent activation energies are 323 kJ mol-' for reaction (5a) and 309 kJ mol-' for reaction (6). These values are in good agreement with the experimental values of (318k10) and al.…”

Section: Discussionsupporting

confidence: 90%

“…(VIII) also can be used to calculate the apparent activation energies for reactions (5a) and (6). In order to check the compatibility of the recommended enthalpies of formation by Anderson, &@ K ( N H~) = 192 and A& K(NH) = 357 kJ mol-' were used in this calculation.…”

Section: Discussionmentioning

confidence: 99%

“…For NH measurements, absorption profiles were converted into concentration profiles using the absorption coefficient a (336.100 nm) = 3.4 -1 O8 cm2/mol as given in [6] and confirmed here.…”

Section: Methodsmentioning

confidence: 99%

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The Thermal Decomposition of NH₂ and NH Radicals

Deppe

Friedrichs

Ibrahim

et al. 1998

Ber Bunsenges Phys Chem

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The formation of NH2 and NH radicals as well as H and N atoms during the thermal decomposition of hydrazine was investigated over a wide temperature range. For the first time frequency-modulated spectroscopy was used for the detection of NHp radicals behind shock waves. In comparison with the dual beam laser absorption technique, the detection limit has been improved by one and a half orders of magnitude.For reaction (5a) NH2+M + NH+H+M the rate constants were obtained in the temperature range from 2200 to 4000 K ks,=(1.2+0.5)10's~exp [-(318* 10) kJ mol-'/RT] cm'lmol s and for reaction (6) N H c M --t N + H + M in the temperature range from 2500 to 3400 K k6=(l.8+0.8)10'4.exp [-(313? 15) kJ mol-'/RT] cm3/mol s.The experimental apparent activation energies were found to be in good agreement with theoretical calculations and recently recommended enthalpies of formation for NH2 and NH. The competing NH2 decomposition channel (5b) NHz+M -+ N+H2+M was shown to be of minor importance ( < 5%). The kinetic behavior of the unimolecular decomposition of NH2 is compared with that of H20 and k H 2 .

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

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The Thermal Decomposition of NH₂ and NH Radicals

Deppe

Friedrichs

Ibrahim

et al. 1998

Ber Bunsenges Phys Chem

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“…Comparing results for the effective absorption coefficients of the 1 CH 2 radical, for example at T = 2000 K and p = 1 bar, with corresponding values of other radical species, like NH 2 [60,96], OH [97] and NH [98], which are also important in combustion processes, one can conclude from the following ratios α(NH) : α(OH) : α(NH 2 ) : α(CH tot 2 ) ≈ 18 980 : 1970 : 32 : 1 the necessity of high sensitivity of the detection system used for time-resolved 1 CH 2 measurements, especially at such high temperatures.…”

Section: Resultsmentioning

confidence: 99%

Detection of 1CH2 Radicals in Hydrocarbon Pyrolysis Behind Shock Waves Using FM Spectroscopy

Deppe¹,

Wagner²

2001

Zeitschrift Für Physikalische Chemie

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“…Even though large uncertainties in high temperature cross sections of small species are not uncommon, , for sure they may seriously limit the accuracy of NCN rate constant determinations in cases where secondary chemistry may not be completely suppressed. Therefore, a reevaluation of the NCN absorption cross section using two independent detection systems and by careful analysis of the purity and stability of the reaction gas mixtures by gas chromatography (GC), Fourier transform infrared spectroscopy (FTIR), and mass spectrometry (MS) has been performed in this work.…”

Section: Introductionmentioning

confidence: 99%

The Reaction NCN + H₂: Quantum Chemical Calculations, Role of ¹NCN Chemistry, and ³NCN Absorption Cross Section

et al. 2020

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The NCN radical plays a key role for modeling prompt-NO formation in hydrocarbon flames. Recently, in a combined shock tube and flame modeling study, the so far neglected reaction NCN + H2 and the related chemistry of the main product HNCN turned out to be significant for NO modeling under fuel-rich conditions. In this study, the reaction has been thoroughly revisited by detailed quantum chemical rate constant calculations both for the singlet 1NCN and triplet 3NCN pathways. Optimized geometries and vibrational frequencies of reactants, products, and transition states were calculated on B3LYP/aug-cc-pVQZ level with single-point energy calculations carried out against the optimized structures using CASPT2/aug-cc-pVQZ. The determined rate constants for the 1NCN + H2 reaction as well as the newly measured high temperature absorption cross section of 3NCN made a reevaluation of the shock tube data of the previous work necessary, finally revealing quantitative agreement between experiment and theory. Moreover, the new directly measured Doppler-limited absorption cross section data, σ(3NCN, λ = 329.1302 nm) = 2.63 × 109 × exp(−1.96 × 10–3 × T/K) cm2/mol (±23%, p = 0 bar, T = 870–1700 K), are in agreement with previously reported values based on detailed spectroscopic simulations. Hence, a long-standing debate about a reliable high temperature 3NCN absorption cross section has been resolved. Whereas 3NCN + H2 resembles a simple abstraction type reaction with the exclusive products HNCN + H, the singlet radical reaction is initiated by the insertion into the H–H bond. Up to pressures of 100 bar, the main products of the subsequent decomposition of the H2NCN intermediate are HNCN + H as well, with minor contributions of CN + NH2 toward higher temperatures. Although much faster than the triplet reaction, the singlet radical insertion is actually rather slow, due to the necessary reorganization of the HOMO electron density in 1NCN that is equally distributed over the two N atom sites. In general, the distinct reactivity differences call for a separate treatment of 1NCN and 3NCN chemistry. However, as the main reaction products in case of the H2 reaction are the same and as the population of the 1NCN in thermal equilibrium remains low, a properly weighted effective rate constant k(NCN + H2 → HNCN + H) = 2.62 × 104 × (T/K)2.78 × exp(−97.6 kJ/mol/RT) cm3 mol–1s–1(±30%, 800 K < T < 3000 K, p < 100 bar) is recommended for inclusion into flame models that, as yet, do not explicitly account for 1NCN chemistry.

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A kinetic study about the reactions of NH(X³Σ⁻) with hydrocarbons part 1: Saturated hydrocarbons and acetaldehyde

Cited by 28 publications

References 20 publications

The Thermal Decomposition of NH₂ and NH Radicals

The Thermal Decomposition of NH₂ and NH Radicals

Detection of 1CH2 Radicals in Hydrocarbon Pyrolysis Behind Shock Waves Using FM Spectroscopy

The Reaction NCN + H₂: Quantum Chemical Calculations, Role of ¹NCN Chemistry, and ³NCN Absorption Cross Section

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A kinetic study about the reactions of NH(X3Σ−) with hydrocarbons part 1: Saturated hydrocarbons and acetaldehyde

Cited by 28 publications

References 20 publications

The Thermal Decomposition of NH2 and NH Radicals

The Thermal Decomposition of NH2 and NH Radicals

Detection of 1CH2 Radicals in Hydrocarbon Pyrolysis Behind Shock Waves Using FM Spectroscopy

The Reaction NCN + H2: Quantum Chemical Calculations, Role of 1NCN Chemistry, and 3NCN Absorption Cross Section

Contact Info

Product

Resources

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A kinetic study about the reactions of NH(X³Σ⁻) with hydrocarbons part 1: Saturated hydrocarbons and acetaldehyde

The Thermal Decomposition of NH₂ and NH Radicals

The Thermal Decomposition of NH₂ and NH Radicals

The Reaction NCN + H₂: Quantum Chemical Calculations, Role of ¹NCN Chemistry, and ³NCN Absorption Cross Section