Kinetics of elementary reactions in low-temperature autoignition chemistry

Zádor, Judit; Taatjes, Craig A.; Fernandes, Ravi X.

doi:10.1016/j.pecs.2010.06.006

Cited by 606 publications

(554 citation statements)

References 486 publications

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“…Considerable work has been performed on the phenyl radical (C 6 H 5 ) and its reactions with O 2 . 1-10 Notably, phenyl oxidation does not follow the ROO -QOOH isomerisation route often encountered when rationalising hydrocarbon radical oxidation; 11 instead, more elaborate peroxyl radical isomerisation channels are accessed. For substituted phenyl radicals there remains significant uncertainty around the key mechanisms and dominant reaction products in their oxidation.…”

Section: Introductionmentioning

confidence: 99%

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Prendergast

Cooper

Kirk

et al. 2013

Phys. Chem. Chem. Phys.

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The reactions of distonic 4-(N,N,N-trimethylammonium)-2-methylphenyl and 5-(N,N,Ntrimethylammonium)-2-methylphenyl radical cations (m/z 149) with O 2 are studied in the gas phase using ion-trap mass spectrometry. Photodissociation (PD) of halogenated precursors gives rise to the target distonic charge-tagged methylphenyl radical whereas collision-induced dissociation (CID) is found to produce unreactive radical ions. The PD generated distonic radicals, however, react rapidly with O2 to form [M + O2]•+ and [M + O2 -OH]•+ ions, detected at m/z 181 and m/z 164, respectively. Quantum chemical calculations using G3SX(MP3) and M06-2X theories are deployed to examine key decomposition pathways of the 5-(N,N,N-trimethylammonium)-2-methylphenylperoxyl radical and rationalise the observed product ions. The prevailing product mechanism involves a 1,5-H shift in the peroxyl radical forming a QOOH-type intermediate that subsequently eliminates •OH to yield charge-tagged 2-quinone methide. Our study suggests that the analogous process should occur for the neutral methylphenyl + O2 reaction, thus serving as a plausible source of •OH radicals in combustion environments. The prevailing product mechanism involves a 1,5-H shift in the peroxyl radical forming a QOOH-type intermediate that subsequently eliminates OH to yield charge-tagged 2-quinone methide. Our study suggests that the analogous process should occur for the neutral methylphenyl + O 2 reaction, thus serving as a plausible source of OH radicals in combustion environments.

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Section: Introductionmentioning

confidence: 99%

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Prendergast

Cooper

Kirk

et al. 2013

Phys. Chem. Chem. Phys.

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“…The subsequent fuel radical, "R", can then react with molecular oxygen. The details of this reaction, and in particular the branching among the possible product channels, is the basis of most of the fuel effects in autoignition (Zádor, Taatjes et al 2010). The formation of an OH radical in the R + O 2 reaction is particularly important, both because OH is an excellent chain carrier and because OH production is kinetically linked to the formation of hydroperoxyalkyl radicals, whose reactions are responsible for low-temperature chain branching (Battin-Leclerc, Herbinet et al 2010).…”

Section: Fundamental Chemistry Experimentsmentioning

confidence: 99%

Analysis of advanced biofuels.

Dec¹,

Taatjes²,

Welz³

et al. 2010

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Long chain alcohols possess major advantages over ethanol as bio-components for gasoline, including higher energy content, better engine compatibility, and less water solubility. Rapid developments in biofuel technology have made it possible to produce C 4 -C 5 alcohols efficiently. These higher alcohols could significantly expand the biofuel content and potentially replace ethanol in future gasoline mixtures. This study characterizes some fundamental properties of a C 5 alcohol, isopentanol, as a fuel for homogeneous-charge compression-ignition (HCCI) engines. Wide ranges of engine speed, intake temperature, intake pressure, and equivalence ratio are investigated. The elementary autoignition reactions of isopentanol is investigated by analyzing product formation from laser-photolytic Cl-initiated isopentanol oxidation. Carbon-carbon bond-scission reactions in the low-temperature oxidation chemistry may provide an explanation for the intermediate-temperature heat release observed in the engine experiments. Overall, the results indicate that isopentanol has a good potential as a HCCI fuel, either in neat form or in blend with gasoline. 4 ACKNOWLEDGMENTSNicolas Dronniou (8362) is acknowledged for his contributions to the HCCI engine experiments, and Judit Zádor and John D. Savee (both 8353), and Giovanni Meloni (University of San Francisco) are acknowledged for their contributions to the experiments at the Advanced Light Source. Ravi X. Fernandes (8353, now RWTH Aachen University) is also acknowledged for his participation in early OH LIF experiments.5

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“…Methyl peroxy (CH 3 O 2 ) radicals are critical intermediates in the atmospheric oxidation (Orlando and Tyndall, 2012) and combustion of hydrocarbons (Zador et al, 2011). In the remote atmosphere, CH 3 O 2 is mainly formed by the reaction of methane with the OH radical via abstraction of an H atom (Reaction R1), followed by the reaction of the produced CH 3 radical with O 2 (Reaction R2).…”

Section: Introductionmentioning

confidence: 99%

A new method for atmospheric detection of the CH<sub>3</sub>O<sub>2</sub> radical

et al. 2017

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Abstract.A new method for measurement of the methyl peroxy (CH 3 O 2 ) radical has been developed using the conversion of CH 3 O 2 into CH 3 O by excess NO with subsequent detection of CH 3 O by fluorescence assay by gas expansion (FAGE) with laser excitation at ca. 298 nm. The method can also directly detect CH 3 O, when no nitric oxide is added. Laboratory calibrations were performed to characterise the FAGE instrument sensitivity using the conventional radical source employed in OH calibration with conversion of a known concentration of OH into CH 3 O 2 via reaction with CH 4 in the presence of O 2 . Detection limits of 3.8 × 10 8 and 3.0 × 10 8 molecule cm −3 were determined for CH 3 O 2 and CH 3 O respectively for a signal-to-noise ratio of 2 and 5 min averaging time. Averaging over 1 h reduces the detection limit for CH 3 O 2 to 1.1 × 10 8 molecule cm −3 , which is comparable to atmospheric concentrations. The kinetics of the second-order decay of CH 3 O 2 via its self-reaction were observed in HIRAC (Highly Instrumented Reactor for Atmospheric Chemistry) at 295 K and 1 bar and used as an alternative method of calibration to obtain a calibration constant with overlapping error limits at the 1σ level with the result of the conventional method of calibration. The overall uncertainties of the two methods of calibrations are similar -15 % for the kinetic method and 17 % for the conventional method -and are discussed in detail. The capability to quantitatively measure CH 3 O in chamber experiments is demonstrated via observation in HIRAC of CH 3 O formed as a product of the CH 3 O 2 self-reaction.

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Kinetics of elementary reactions in low-temperature autoignition chemistry

Cited by 606 publications

References 486 publications

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Analysis of advanced biofuels.

A new method for atmospheric detection of the CH<sub>3</sub>O<sub>2</sub> radical

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Kinetics of elementary reactions in low-temperature autoignition chemistry

Cited by 606 publications

References 486 publications

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Analysis of advanced biofuels.

A new method for atmospheric detection of the CH&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; radical

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A new method for atmospheric detection of the CH<sub>3</sub>O<sub>2</sub> radical