A detailed kinetic model for aromatics formation from small hydrocarbon and gasoline surrogate fuel combustion

Langer, Raymond; Mao, Qian; Pitsch, Heinz

doi:10.1016/j.combustflame.2022.112574

Cited by 13 publications

(12 citation statements)

References 252 publications

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“…Calculated extinction strain rates of the CH 4 –NH 3 flames using the mechanisms from Shrestha et al, CRECK, and ITV. , …”

Section: Methodsmentioning

confidence: 99%

“…The first mechanism is from Cai et al 37 (referred to as ITV 2015) with 339 species and 2791 reactions (forward and backward counted separately), where the NH 3 chemistry is taken from the GRI-Mech 3.0 mechanism. 38 The second mechanism is an updated version of the same mechanism from Langer et al 39 (referred to as ITV 2021), where the polycyclic aromatic hydrocarbon (PAH) chemistry was largely improved, with 1039 species and up to 6139 reactions. This updated version still uses the same NO x /NH 3 chemistry from the GRI-Mech 3.0 mechanism.…”

Section: Simulation Detailsmentioning

confidence: 99%

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Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Chu,

Scialabba,

Liu

et al. 2023

Energy Fuels

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The global extinction limits of non-premixed nitrogen/ammonia-substituted methane− and ethylene−air counterflow flames were experimentally evaluated. In comparison to nitrogen substitution, ammonia substitution reduced the extinction strain rates more. Measurements of OH* chemiluminescence, of which the intensity correlates with extinction limits, suggest that ammonia substitution reduces OH* production. The effects of transport, thermal and chemical properties on flame extinction of the ammonia-substituted flames were assessed, and it was found that their lower extinction limits were due to reactions that consume radicals, which hinder the chain-branching reactions. To mimic the effect of exhaust gas recirculation on the extinction limits of ammonia-substituted flames, carbon dioxide was added to the oxidizer stream. Lower extinction limits were observed with carbon dioxide addition as a result of thermal and chemical effects. Carbon dioxide addition lowered flame temperatures and, like ammonia substitution, introduced reactions that consume radicals. Nitric oxide (NO) production was quantitatively analyzed by simulations. It was found that, for ammonia flames, NO production was promoted by ammonia oxidation with OH, whereas for carbon dioxide addition, NO production was suppressed by the reduction of OH production.

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“…Calculated extinction strain rates of the CH 4 –NH 3 flames using the mechanisms from Shrestha et al, CRECK, and ITV. , …”

Section: Methodsmentioning

confidence: 99%

Section: Simulation Detailsmentioning

confidence: 99%

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Chu,

Scialabba,

Liu

et al. 2023

Energy Fuels

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“…• self-recombination to form three-membered ring aromatic species was also estimated from that of the analogous reaction of the propargyl radical. 4,69 The kinetics of the complex C 7 H 5…”

Section: Kinetic Modelingmentioning

confidence: 99%

“…Recent kinetic modeling studies − based upon flame-sampling and jet stirred reactor pyrolysis experiments strongly indicate that a highly resonantly stabilized free radical fulvenallenyl (C 7 H 5 · ), which was first proposed by da Silva and Bozzelli as a combustion intermediate, can play a significant role in the gas-phase synthesis of the prototype two-ring polycyclic aromatic hydrocarbon (PAH) naphthalene (C 10 H 8 ). The emergence of naphthalene sets off the growth of PAHs in combustion flames eventually leading to the formation of soot.…”

Section: Introductionmentioning

confidence: 99%

“…Conversely, naphthalene formation in counterflow diffusion flames of various fuels such as acetylene, ethylene, and butene is generally overpredicted also in other literature models. 34 Especially in acetylene and ethylene flames, the interaction between C7 and C3 species (e.g., benzyl, fulvenallenyl, propargyl, propyne, and allene) is key to naphthalene growth. 34 Therefore, a more comprehensive inclusion of "C7" aromatic chemistry is required for the improvement, 35 where fulvenallenyl, along with benzyl, vinylcyclopentadienyl, and tropyl represent crucial intermediates.…”

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confidence: 99%

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Fulvenallenyl Radical (C₇H₅^·)-Mediated Gas-Phase Synthesis of Bicyclic Aromatic C₁₀H₈ Isomers: Can Fulvenallenyl Efficiently React with Closed-Shell Hydrocarbons?

Mebel,

Li,

Pratali Maffei

et al. 2024

J. Phys. Chem. A

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To understand the reactivity of resonantly stabilized radicals, often found in relevant concentrations in gaseous environments, it is important to determine their main reaction pathways. Here, it is investigated whether the fulvenallenyl radical (C 7 H 5• ) reacts preferentially with closed-shell molecules or radicals. Electronic structure calculations on the C 10 H 9 potential energy surface accessed by the reactions of C 7 H 5• with methylacetylene (CH 3 CCH) and allene (H 2 CCCH 2 ) were combined with RRKM-ME calculations of temperature-and pressure-dependent rate constants using the automated EStokTP software suite and kinetic modeling to assess the reactivity of C 7 H 5 • with closed-shell unsaturated hydrocarbons. Experimentally, the reactions were attempted in a chemical microreactor heated to 998 ± 10 K by preparing fulvenallenyl radicals via pyrolysis of trichloromethylbenzene (C 7 H 5 Cl 3 ) and seeding the radicals in methylacetylene or allene carrier gas, with product identification by means of photoionization mass spectrometry. The measured photoionization efficiency curve of m/z = 128 was assigned to a linear combination of the reference curves of two C 10 H 8 isomers, azulene (minor) and naphthalene (major), presumably resulting from the C 7 H 5• plus C 3 H 4 reactions. However, the calculations demonstrated that these reactions are too slow, and kinetic modeling of processes in the reactor allowed us to conclude that the observation of naphthalene and azulene is due to the C 7 H 5• plus C 3 H 3 • reaction, where propargyl is produced by direct hydrogen atom abstraction by chlorine (Cl) atoms from allene or methylacetylene and Cl stem from the pyrolysis of C 7 H 5 Cl 3 . Modeling results under the copyrolysis conditions of toluene and methylacetylene in high-temperature shock tube experiments confirmed the prevalence of the fulvenallenyl reaction with propargyl over its reactions with C 3 H 4 even when the concentrations of allene and methylacetylene largely exceed that of propargyl. Overall, the reactions of fulvenallenyl with both allene and methylacetylene were found to be noncompetitive in the formation of naphthalene and azulene thus attesting the inefficiency of the fulvenallenyl radical reactions with the prototype closed-shell hydrocarbon species. In the meantime, the new reaction pathways revealed, including Hassisted isomerizations between C 10 H 8 isomers and decomposition reactions of various C 10 H 9 isomers, emerge as relevant and are recommended for inclusion in combustion kinetic models for naphthalene formation.

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Reaction path identification and validation from molecular dynamics simulations of hydrocarbon pyrolysis

Schmalz,

Kopp,

Goudeli

et al. 2024

Int J of Chemical Kinetics

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Creation of complex chemical mechanisms for hydrocarbon pyrolysis and combustion is challenging due to the large number of species and reactions involved. Reactive molecular dynamics (RMD) enables the simulation of thousands of reactions and the discovery of previously unknown components of the reaction network. However, due to the inherent imprecision of reactive force fields, it is necessary to verify RMD‐obtained reaction paths using more accurate methods such as Density Functional Theory (DFT). We demonstrate a method for identification and confirmation of reaction pathways from RMD that supplement an established mechanism, using the example of benzene formation from n‐heptane and iso‐octane pyrolysis. We establish a validation workflow to extract reaction geometries from RMD and optimize transition states using the Nudged‐Elastic‐Band method on semi‐empirical and quantum mechanical levels of theory. Our findings demonstrate that the widely recognized ReaxFF parameterization, CHO2016, can identify known pathways from a established soot formation mechanism while also indicating new ones. We also show that CHO2016 underestimates hydrogen migration barriers by up to as compared to DFT and can lower activation barriers significantly for spin‐forbidden reactions. This highlights the necessity for validation or potentially even reparametrization of CHO2016.

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A detailed kinetic model for aromatics formation from small hydrocarbon and gasoline surrogate fuel combustion

Cited by 13 publications

References 252 publications

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Fulvenallenyl Radical (C₇H₅^·)-Mediated Gas-Phase Synthesis of Bicyclic Aromatic C₁₀H₈ Isomers: Can Fulvenallenyl Efficiently React with Closed-Shell Hydrocarbons?

Reaction path identification and validation from molecular dynamics simulations of hydrocarbon pyrolysis

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A detailed kinetic model for aromatics formation from small hydrocarbon and gasoline surrogate fuel combustion

Cited by 13 publications

References 252 publications

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Fulvenallenyl Radical (C7H5·)-Mediated Gas-Phase Synthesis of Bicyclic Aromatic C10H8 Isomers: Can Fulvenallenyl Efficiently React with Closed-Shell Hydrocarbons?

Reaction path identification and validation from molecular dynamics simulations of hydrocarbon pyrolysis

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Fulvenallenyl Radical (C₇H₅^·)-Mediated Gas-Phase Synthesis of Bicyclic Aromatic C₁₀H₈ Isomers: Can Fulvenallenyl Efficiently React with Closed-Shell Hydrocarbons?