A smog chamber and modeling study of the gas phase NO<sub>x</sub>–air photooxidation of toluene and the cresols

Atkinson, Roger; Carter, William; Darnall, Karen R.; Winer, Arthur M.; Pitts, James N.

doi:10.1002/kin.550121102

Cited by 179 publications

(152 citation statements)

References 70 publications

(81 reference statements)

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“…Smog chambers are extensively used to conduct aging experiments on anthropogenic aerosols and investigate their potential to form SOA (Izumi and Fukuyama, 1990;Atkinson et al, 1980;Sidhu et al, 2001). Recently, flow-through reactors are drawing a great deal of attention for their advantages over smog chambers.…”

Section: A M Pourkhesalian Et Al: Effect Of Atmospheric Aging On Vmentioning

confidence: 99%

Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles

et al. 2015

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Abstract. In the prospect of limited energy resources and climate change, effects of alternative biofuels on primary emissions are being extensively studied. Our two recent studies have shown that biodiesel fuel composition has a significant impact on primary particulate matter emissions. It was also shown that particulate matter caused by biodiesels was substantially different from the emissions due to petroleum diesel. Emissions appeared to have higher oxidative potential with the increase in oxygen content and decrease of carbon chain length and unsaturation levels of fuel molecules. Overall, both studies concluded that chemical composition of biodiesel is more important than its physical properties in controlling exhaust particle emissions. This suggests that the atmospheric aging processes, including secondary organic aerosol formation, of emissions from different fuels will be different as well. In this study, measurements were conducted on a modern common-rail diesel engine. To get more information on realistic properties of tested biodiesel particulate matter once they are released into the atmosphere, particulate matter was exposed to atmospheric oxidants, ozone and ultraviolet light; and the change in their properties was monitored for different biodiesel blends. Upon the exposure to oxidative agents, the chemical composition of the exhaust changes. It triggers the cascade of photochemical reactions resulting in the partitioning of semi-volatile compounds between the gas and particulate phase. In most of the cases, aging lead to the increase in volatility and oxidative potential, and the increment of change was mainly dependent on the chemical composition of fuels as the leading cause for the amount and the type of semi-volatile compounds present in the exhaust.

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Section: A M Pourkhesalian Et Al: Effect Of Atmospheric Aging On Vmentioning

confidence: 99%

Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles

et al. 2015

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“…However, most quantitative evidence has been found for intermediates that are consistent with the ring-opening route proposed by Atkinson et al (1980). A number of mechanisms have been developed to describe the photooxidation of aromatic compounds (Liang and Jacobson, 2000).…”

Section: Figmentioning

confidence: 99%

“…With 670 implemented reactions for the photooxidation of toluene, the MCM v3 aims to reflect the most detailed current knowledge in the field of toluene photo-oxidation (http://www.chem.leeds.ac.uk/ Atmospheric/MCM/mcmproj.html). According to the historic development in the field of aromatic photooxidation, the MCM v1, launched in 1997, contained a toluene mechanism based mainly on a ring-opening route as proposed by Atkinson et al (1980). For MCM v2 a toluene mechanism was developed that explored the proposed degradation route involving the formation of aromatic oxide/oxepin intermediates (Klotz et al, 2000).…”

Section: Figmentioning

confidence: 99%

“…The two prevailing ring-retaining routes, which form cresol and benzaldehyde as first generation products, are comparatively well understood (Atkinson, 1992;Klotz et al, 1998;Volkamer et al, 2002), whereas the chemistry of the ringopening routes is still very speculative (Smith et al, 1998;Volkamer et al, 2001;. Over the past years several ring-opening routes have been proposed in line with emerging experimental information (Atkinson et al, 1980;Bartolotti and Edney, 1995;Klotz et al, 1997 Fig. 1.…”

Section: Introductionmentioning

confidence: 98%

“…Based on detection of ring-opening products, such as glyoxal and methylglyoxal, Atkinson et al (1980) proposed a reaction channel (here labelled as dicarbonyl route) in which the ring breaks down via a series of peroxide-bicyclic intermediates eventually forming α-dicarbonyls (glyoxal and methylglyoxal) and conjugated γ -dicarbonyls (butenedial, 2-methylbutenedial and 4-oxo-2-pentenal). In the mid-nineties quantum mechanical calculations published by Bartolotti and Edney (1995) suggested that an epoxide-type compound is the most stable intermediate following the OH addition to the ring.…”

Section: Introductionmentioning

confidence: 99%

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Modelling of the photooxidation of toluene: conceptual ideas for validating detailed mechanisms

et al. 2003

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Abstract. Toluene photooxidation is chosen as an example to examine how simulations of smog-chamber experiments can be used to unravel shortcomings in detailed mechanisms and to provide information on complex reaction systems that will be crucial for the design of future validation experiments. The mechanism used in this study is extracted from the Master Chemical Mechanism Version 3 (MCM v3) and has been updated with new modules for cresol and γ -dicarbonyl chemistry. Model simulations are carried out for a toluene-NO x experiment undertaken at the European Photoreactor (EUPHORE). The comparison of the simulation with the experimental data reveals two fundamental shortcomings in the mechanism: OH production is too low by about 44%, and the ozone concentration at the end of the experiment is over-predicted by 55%. The radical budget was analysed to identify the key intermediates governing the radical transformation in the toluene system. Ring-opening products, particularly conjugated γ -dicarbonyls, were identified as dominant radical sources in the early stages of the experiment. The analysis of the time evolution of radical production points to a missing OH source that peaks when the system reaches highest reactivity. First generation products are also of major importance for the ozone production in the system. The analysis of the radical budget suggests two options to explain the concurrent under-prediction of OH and overprediction of ozone in the model: (1) missing oxidation processes that produce or regenerate OH without or with little NO to NO 2 conversion or (2) NO 3 chemistry that sequesters reactive nitrogen oxides into stable nitrogen compounds and at the same time produces peroxy radicals. Sensitivity analyCorrespondence to: M. J. Pilling (M.J.Pilling@chem.leeds.ac.uk sis was employed to identify significant contributors to ozone production and it is shown how this technique, in combination with ozone isopleth plots, can be used for the design of validation experiments.

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DFT and MP2 molecular orbital determination of OH-toluene-O2 isomeric structures in the atmospheric oxidation of toluene

Garca-Cruz¹,

Castro²,

Vivier–Bunge³

2000

J. Comput. Chem.

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We have performed an exhaustive theoretical study, using a density functional theory (DFT) and ab initio techniques, of the possible isomers of the OH–toluene–O2 radical. DFT calculations of the all electron type using the hybrid B3LYP approach and 6‐31G* orbital basis set were employed. In addition to the well‐established ortho position, addition of OH at C1 on the benzene ring of toluene was also considered for the initial methylhydroxycyclohexadienyl adduct. In all, 28 different intermediate structures of the OH–toluene–O2 system, consisting of peroxyl radicals, bicyclic structures, and epoxides, have been explored through fully optimized electronic structure calculations. Starting from the 1,3‐O2‐methylorthohydroxycyclohexadienyl radical, or ortho‐OH adduct, several peroxyl radicals are found to have low‐lying structures contained within a small energy range (about 1 kcal/mol). Only two bicyclic structures are stable with respect to the methylhydroxycyclohexadienyl radical plus O2, one of them being clearly favored. The four possible epoxy structures are all found to lie more than 15 kcal/mol lower than any of their peroxyl and bicyclic isomers. The preference, first noted by Bartolotti and Edney, for structures in which the OH group lies on the same side of the ring as the O2 group, is obeyed in all cases. If the 1‐CH3, 1‐OH cyclohexadienyl radical (or C1–OH adduct) is used as the initial adduct, three peroxyl radicals are expected to be formed, while two bicyclic structure and three epoxides need to be considered. These structures are found to be, in general, less stable than the ones arising from the ortho adduct. However, the 4‐O, 2,3‐epoxy, 1,1‐methylhydroxycyclohexadienyl radical is found to be the most stable of all the isomers considered, and this, by more than 3 kcal/mol. In this work, most structures were also calculated with the MP2 method with a 6‐31G* basis set. The geometries obtained with the two methods are similar. Contrary to the B3LYP method, MP2 always yields an extra stability to structures in which the C1 carbon atom has sp3 hybridization. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 716–730, 2000

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A smog chamber and modeling study of the gas phase NO_x–air photooxidation of toluene and the cresols

Cited by 179 publications

References 70 publications

Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles

Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles

Modelling of the photooxidation of toluene: conceptual ideas for validating detailed mechanisms

DFT and MP2 molecular orbital determination of OH-toluene-O2 isomeric structures in the atmospheric oxidation of toluene

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A smog chamber and modeling study of the gas phase NOx–air photooxidation of toluene and the cresols

Cited by 179 publications

References 70 publications

Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles

Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles

Modelling of the photooxidation of toluene: conceptual ideas for validating detailed mechanisms

DFT and MP2 molecular orbital determination of OH-toluene-O2 isomeric structures in the atmospheric oxidation of toluene

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A smog chamber and modeling study of the gas phase NO_x–air photooxidation of toluene and the cresols