Theoretical derivation for reaction rate constants of H abstraction from thiophenol by the H/O radical pool

Batiha, Marwan M.; Altarawneh, Mohammednoor; Al-Harahsheh, Mohammad; Altarawneh, Ibrahem; Rawadieh, Saleh

doi:10.1016/j.comptc.2011.05.015

Cited by 9 publications

(6 citation statements)

References 27 publications

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“…Mathieu et al lowered the Zhou rate constant by a factor of 2 to improve agreement with their experiments. Recent calculations indicate a much lower rate constant, but the level of theory (G3B3 and CBS-QB3) used was lower than that of Zhou . In the present work, we have adopted the value of Mathieu et al, but an accurate determination of this rate constant is desirable.…”

Section: Detailed Kinetic Modelmentioning

confidence: 91%

Experimental and Modeling Investigation of the Effect of H₂S Addition to Methane on the Ignition and Oxidation at High Pressures

et al. 2016

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The autoignition and oxidation behavior of CH4/H2S mixtures has been studied experimentally in a rapid compression machine (RCM) and a high-pressure flow reactor. The RCM measurements show that the addition of 1% H2S to methane reduces the autoignition delay time by a factor of 2 at pressures ranging from 30 to 80 bar and temperatures from 930 to 1050 K. The flow reactor experiments performed at 50 bar show that, for stoichiometric conditions, a large fraction of H2S is already consumed at 600 K, while temperatures above 750 K are needed to oxidize 10% methane. A detailed chemical kinetic model has been established, describing the oxidation of CH4 and H2S as well as the formation and consumption of organosulfuric species. Computations with the model show good agreement with the ignition measurements, provided that reactions of H2S and SH with peroxides (HO2 and CH3OO) are constrained. A comparison of the flow reactor data to modeling predictions shows satisfactory agreement under stoichiometric conditions, while at very reducing conditions, the model underestimates the consumption of both H2S and CH4. Similar to the RCM experiments, the presence of H2S is predicted to promote oxidation of methane. Analysis of the calculations indicates a significant interaction between the oxidation chemistry of H2S and CH4, but this chemistry is not well understood at present. More work is desirable on the reactions of H2S and SH with peroxides (HO2 and CH3OO) and the formation and consumption of organosulfuric compounds.

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Section: Detailed Kinetic Modelmentioning

confidence: 91%

Experimental and Modeling Investigation of the Effect of H₂S Addition to Methane on the Ignition and Oxidation at High Pressures

et al. 2016

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“…39 Despite a noticeable difference in the endothermicities of the H−O/S bonds, abstraction of the thiol's H by the O/H radical pool proceeds with rate constants comparable to those corresponding to hydroxyl's H in 2-chlorophenol. 40 The difference between the two compounds could also be rationalized within the formalism of the electron density distribution. As the OH constitutes a stronger electron donating group than SH, one expects that, the π-conjugated system in the 2-CTP molecule displays less nucleophilic character in reference to that of the 2-CP molecule.…”

Section: Computational Detailsmentioning

confidence: 98%

Quantum Chemical Study on Formation of PCDT/TA from 2-Chlorothiophenol Precursor

Dar

Altarawneh

Dlugogorski

2013

Environ. Sci. Technol.

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This contribution investigates the thermochemical and kinetic parameters pertinent to the homogeneous gas-phase formation of two groups of pollutants, polychlorinated dibenzothiophenes (PCDT) and polychlorinated thianthrenes (PCTA) from their 2-chlorothiophenol (2-CTP) precursor. We compare the enthalpic profiles of the formation mechanism of PCDT/TA with the corresponding reactions involved in the gas-phase synthesis of PCDD/F (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, also known as dioxins). Overall, the presence of sulfur atoms greatly reduces the activation enthalpies of the rate determining steps in reference to the oxygenated system of PCDD/F. The rate constants of all elementary reactions are calculated using the transition state theory (TST) over a wide temperature range of 300-1200 K. We performed kinetic calculations for the formation of chlorinated dibenzothiophenes and chlorinated thianthrenes that could be applied to predict yields of these pollutants from 2-CTP up to ∼1200 K, that is, prior to the emergence of dechlorination and oxidation reactions. The results presented herein provide a greatly improved understanding of the gas-phase formation of the sulfur analogs of the notorious dioxins compounds.

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“…For instance, theoretically calculated reaction rate constants for H abstraction from alkanes (up to butanes) by Aguilera-Iparraguirre et al 17 were in accord with recommended analogous values by Walker. 15 Likewise, we have utilized density functional theory (DFT) calculations and chemistry models to compute rate constants for H abstraction by HO 2 from a large array of compounds including methanol, 18 benzene, 19 mercaptans, 20 and alkylated benzenes. 21,22 Despite the progress on the theoretical side, the literature presents a rather limited account of kinetics data germane to H abstraction by HO 2 from an important fuel's category, that is, alcohols.…”

Section: Introductionmentioning

confidence: 99%

Reaction of Hydroperoxy Radicals with Primary C_1–5 Alcohols: A Profound Effect on Ignition Delay Times

Rawadieh¹,

Altarawneh

Batiha³

et al. 2019

Energy Fuels

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Ignition delay times of primary alcohols often display a noticeable sensitivity to their initial reactions with HO 2 radicals. In view of the transient nature of HO 2 radicals, kinetic models on combustion of alcohols utilize theoretically obtained constant parameters for the abstraction HO 2 + alcohols reactions. Rate constants for the title reactions in pertinent kinetic models are often extrapolated from analogous computed values for either alkanes + HO 2 or n-butane + HO 2 reactions. Even for the simplest alcohol, methanol, literature values for the reaction rate constants considerably vary within one order of magnitude. Herein, we compute reaction rate constants for H abstraction from the weakest sites in primary C 1−5 alcohols by HO 2 (methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, n-pentanol, and i-pentanol). In most cases, our reaction rate coefficients tend to slightly exceed corresponding values deployed in pertinent kinetic models. We have thoroughly assessed the predictive performance of literature kinetic models in computing ignition delay times of these alcohols based on the updated rate constants for HO 2 -abstraction reactions. In the case of methanol, updating kinetic parameters for the reaction CH 3 OH + HO 2 → CH 2 OH + H 2 O 2 improves prediction of ignition delay times at lower temperatures in reference to original literature kinetic models. Likewise, a modified kinetic model for n-butane and t-butanol affords better agreement with experimental values of ignition delay times at low temperatures and high pressures. Kinetic parameters presented herein will be useful to accurately account for salient oxidation features of alcohols in real combustion engines.

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Theoretical derivation for reaction rate constants of H abstraction from thiophenol by the H/O radical pool

Cited by 9 publications

References 27 publications

Experimental and Modeling Investigation of the Effect of H₂S Addition to Methane on the Ignition and Oxidation at High Pressures

Experimental and Modeling Investigation of the Effect of H₂S Addition to Methane on the Ignition and Oxidation at High Pressures

Quantum Chemical Study on Formation of PCDT/TA from 2-Chlorothiophenol Precursor

Reaction of Hydroperoxy Radicals with Primary C_1–5 Alcohols: A Profound Effect on Ignition Delay Times

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Theoretical derivation for reaction rate constants of H abstraction from thiophenol by the H/O radical pool

Cited by 9 publications

References 27 publications

Experimental and Modeling Investigation of the Effect of H2S Addition to Methane on the Ignition and Oxidation at High Pressures

Experimental and Modeling Investigation of the Effect of H2S Addition to Methane on the Ignition and Oxidation at High Pressures

Quantum Chemical Study on Formation of PCDT/TA from 2-Chlorothiophenol Precursor

Reaction of Hydroperoxy Radicals with Primary C1–5 Alcohols: A Profound Effect on Ignition Delay Times

Contact Info

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About

Experimental and Modeling Investigation of the Effect of H₂S Addition to Methane on the Ignition and Oxidation at High Pressures

Experimental and Modeling Investigation of the Effect of H₂S Addition to Methane on the Ignition and Oxidation at High Pressures

Reaction of Hydroperoxy Radicals with Primary C_1–5 Alcohols: A Profound Effect on Ignition Delay Times