Effects of gasoline aromatic and lead content on exhaust hydrocarbon reactivity

Heuss, Jon M.; Nebel, George J.; D'Alleva, B.A.

doi:10.1021/es60092a002

Cited by 14 publications

(6 citation statements)

References 7 publications

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“…A critical need remains, however, for kinetic and mechanistic data for the reactions of OH with aromatic compounds in the gas phase (15)(16)(17). This is apparent, not only from the standpoint of the need to develop validated kinetic mechanisms of photochemical smog formation (6)(7)(8)(18)(19)(20), but also with respect to the increased use of aromatic compounds in unleaded gasoline (21) and the resultant increase in ambient concentration of aromatics (22,23) over those already present due to the use of solvents (24).…”

Section: Discussionmentioning

confidence: 99%

Gas phase kinetic study of relative rates of reaction of selected aromatic compounds with hydroxyl radicals in an environmental chamber

Doyle¹,

Lloyd²,

Darnall³

et al. 1975

Environ. Sci. Technol.

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Section: Discussionmentioning

confidence: 99%

Gas phase kinetic study of relative rates of reaction of selected aromatic compounds with hydroxyl radicals in an environmental chamber

Doyle¹,

Lloyd²,

Darnall³

et al. 1975

Environ. Sci. Technol.

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“…Aromatic hydrocarbons are recognized to be an important constituent of anthropogenic emissions in polluted urban atmospheres [l], and, for instance, toluene levels of -250 ppb (parts per billion) have been reported in Japan [2] and levels of -40 ppb are common in the California South Coast Air Basin [3,4].…”

Section: Introductionmentioning

confidence: 99%

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

Atkinson

Carter

Darnall

et al. 1980

Int J of Chemical Kinetics

180

135

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An experimental and modeling study of irradiated toluene-NO,-air, toluene-benzaldehyde-NO,-air, and cresol-NO,-air mixtures a t part-per-million concentrations has been carried out. These mixtures were irradiated a t 303 f 1 K in a 5800-liter Teflon-lined, evacuable environmental chamber, with temperature, humidity, light intensity, spectral distribution, and the concentrations of 0 3 , NO, NOz, toluene, PAN, formaldehyde, benzaldehyde, o-cresol, m-nitrotoluene, and methyl nitrate being monitored as a function of time. For the toluene and toluene-benzaldehyde-NO,-air runs a variety of initial reactant concentrations were investigated. Cresol-NO,-air runs were observed to be much less reactive in terms of 0 3 formation and NO to NO2 conversion rates than toluene-NO,-air runs, with the relative reactivity of the cresol isomers being in the order meta >> ortho > para. The addition of benzaldehyde to toluene-NO,-air mixtures decreased the reactivity, in agreement with previous studies. Alternative mechanistic pathways for the NO, photooxidations of aromatic systems in general are discussed, and the effects of varying these mechanistic alternatives on the model predictions for the toluene and o-cresol-NO,-air systems are examined. Fits of the calculations to most of the experimental concentration-time profiles could be obtained to within the experimental uncertainty for two of the mechanistic options considered. In both cases it is assumed that (1) 0 2 adds to the OH-toluene adduct -75% of the time forming, after a further addition of 0 2 , a C7 bicyclic peroxy radical, and (2) this C7 bicyclic peroxy radical reacts with NO -75% of the time to ultimately form a-dicarbonyls and conjugated y-dicarbonyls (e.g., methylglyoxal + 2-butene-1,4-dial) and -25% of the time to form organic nitrates.The major uncertainties in the mechanisms concern (1) the structure of the bicyclic peroxy intermediate, and (2) the y-dicarbonyl photooxidation mechanism. Good fits to the o-cresol concentration-time profiles in the toluene-NO, runs are obtained if it is assumed that o-cresol

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“…The mechanism of its formation is reasonably well understood; it results from the NO,-air photooxidation of acetaldehyde (3)(4)(5) and other organics (5,6) present in polluted atmospheres. Specifically it is formed from the reaction of NO2 with peroxyacetyl radicals formed in hydrocarbon-NO, photooxidations.…”

Section: Introductionmentioning

confidence: 99%

“…These rate constants mean that reaction with NO3 can be a major sink for phenolic compounds under conditions of photochemical air pollution, especially at night. Possible mechanisms accounting for these results are discussed.Aromatic hydrocarbons constitute a significant portion of the reactive organics emitted into polluted urban atmospheres (1)(2)(3)(4), and substituted phenols are among the products of their NO,-air photooxidation (5-12). However, the subsequent fates of these products in atmospheric systems are not well understood.…”

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confidence: 99%

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Major atmospheric sink for phenol and the cresols. Reaction with the nitrate radical

Carter¹,

Winer²,

Pitts³

1981

Environ. Sci. Technol.

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Evidence has been obtained from studies using two different environmental chambers that phenol and the cresols react rapidly with the nitrate radical (NO3). When a relative rate technique reliable to within at least a factor of 2 was used, the following rate constants for reaction with NO3 a t 300 f 1 K were derived (cm3 molecule-l s-'): phenol, 2 X 10-l2; o-cresol, 1.2 X lo-''; rn-cresol, 7 X p-cresol, 1.3 X lo-".Methoxybenzene, benzaldehyde, and toluene reacted with NO3 too slowly to measure by the techniques employed in this study, and only upper limits of 1 3 X 10-15-8 X cm3 molecule-' s-' could be determined. These rate constants mean that reaction with NO3 can be a major sink for phenolic compounds under conditions of photochemical air pollution, especially at night. Possible mechanisms accounting for these results are discussed.Aromatic hydrocarbons constitute a significant portion of the reactive organics emitted into polluted urban atmospheres (1)(2)(3)(4), and substituted phenols are among the products of their NO,-air photooxidation (5-12). However, the subsequent fates of these products in atmospheric systems are not well understood. For example, cresols are formed in environmental chamber irradiations of toluene-NO,-air mixtures (5-71, but, after their initial buildup, their concentrations decrease a t a rate faster than can be attributed to their known reactions with hydroxyl radicals (8, 13, 14) or with ozone (9, 13). Although this rapid decrease in the cresol concentration generally occurs around the time that NO is consumed and 0 3 begins to build up, it cannot be attributed to reaction between the cresol and 0 3 since the rate constants for these reactions have been measured (9,13) and are too low for them to be of importance in atmospheric systems. This apparent excess rate of decay of the cresols could possibly be due to an experimental artifact in sampling for cresols in the presence of 0 3 , and this possibility is examined in this study.An alternative possibility is that there could be some unknown aspect of the aromatic photooxidation mechanism causing cresol production to decrease around the time 0 3 formation begins or that some other species formed in such experiments reacts rapidly with cresols. For example, nitrate radicals (NOS) are formed in photochemical smog systems from the reaction of O3 with NO2(1) and it may be reaction with this species which accounts for the excess rates of cresol consumption. On the basis of results of experiments reported here, we believe that this is the most probable explanation.Exploratory Runs. Five experiments were conducted in which 200-1400 ppb of 0 3 was injected into the SAPRC -6OOO-L, all-glass chamber (15-17) containing 10-100 ppb of cresols; o-cresol was used most frequently, but similar results were observed for all three isomers. The O3 injections in the absence of NO, resulted in immediate and highly variable decreases in measured cresol concentrations, ranging from 1 to 30 ppb, with the amount of reduction having no obvious dependence on t...

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Effects of gasoline aromatic and lead content on exhaust hydrocarbon reactivity

Cited by 14 publications

References 7 publications

Gas phase kinetic study of relative rates of reaction of selected aromatic compounds with hydroxyl radicals in an environmental chamber

Gas phase kinetic study of relative rates of reaction of selected aromatic compounds with hydroxyl radicals in an environmental chamber

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

Major atmospheric sink for phenol and the cresols. Reaction with the nitrate radical

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Effects of gasoline aromatic and lead content on exhaust hydrocarbon reactivity

Cited by 14 publications

References 7 publications

Gas phase kinetic study of relative rates of reaction of selected aromatic compounds with hydroxyl radicals in an environmental chamber

Gas phase kinetic study of relative rates of reaction of selected aromatic compounds with hydroxyl radicals in an environmental chamber

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

Major atmospheric sink for phenol and the cresols. Reaction with the nitrate radical

Contact Info

Product

Resources

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