The atmospheric chemistry of Oxygenated fuel additives: <i>t</i>‐Butyl alcohol, dimethyl ether, and methyl<i>t</i>‐butyl ether

Japar, Steven M.; Wallington, Timothy J.; Richert, Joel F. O.; Ball, James C.

doi:10.1002/kin.550221205

Cited by 143 publications

(177 citation statements)

References 14 publications

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“…The methanol oxidation pathway as outlined above produces higher numbers of reactive radicals than the methane oxidation pathway and hence the observed values. Table VII shows that at the higher temperature of 1600 K hydrogen abstraction reactions are much more competitive in terms of fuel consumption than at 1450 K. At higher temperatures, the concerted elimination reactions actually become inhibitive to the global oxidation reaction as their activity introduces chemically inert CO and CO 2 and relatively unreactive CH 4 , slowing the growth of the radical pool.…”

Section: Shock Tubementioning

confidence: 95%

Methyl formate oxidation: Speciation data, laminar burning velocities, ignition delay times, and a validated chemical kinetic model

Dooley

Burke

Chaos

et al. 2010

Int J of Chemical Kinetics

150

204

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The oxidation of methyl formate (CH 3 OCHO) has been studied in three experimental environments over a range of applied combustion relevant conditions: 1. A variable-pressure flow reactor has been used to quantify reactant, major intermediate and product species as a function of residence time at 3 atm and 0.5% fuel concentration for oxygen/fuel stoichiometries of 0.5, 1.0, and 1.5 at 900 K, and for pyrolysis at 975 K. 2. Shock tube ignition delays have been determined for CH 3 OCHO/O 2 /Ar mixtures at pressures of ≈ 2.7, 5.4, and 9.2 atm and temperatures of 1275-1935 K for mixture compositions of 0.5% fuel (at equivalence ratios of 1.0, 2.0, and 0.5) and 2.5% fuel (at an equivalence ratio of 1.0). 3. Laminar burning velocities of outwardly propagating spherical CH 3 OCHO/air flames have been determined for stoichiometries ranging from 0.8-1.6, at atmospheric pressure using a pressure-release-type high-pressure chamber.A detailed chemical kinetic model has been constructed, validated against, and used to interpret these experimental data. The kinetic model shows that methyl formate oxidation proceeds through concerted elimination reactions, principally forming methanol and carbon monoxide as well as through bimolecular hydrogen abstraction reactions. The relative importance of elimination versus abstraction was found to depend on the particular environment. In general, methyl formate is consumed exclusively through molecular decomposition in shock tube environments, while at flow reactor and freely propagating premixed flame conditions, there is significant competition between hydrogen abstraction and concerted elimination channels. It is suspected that in diffusion flame configurations the elimination channels contribute more significantly than in premixed environments. C

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Section: Shock Tubementioning

confidence: 95%

Methyl formate oxidation: Speciation data, laminar burning velocities, ignition delay times, and a validated chemical kinetic model

Dooley

Burke

Chaos

et al. 2010

Int J of Chemical Kinetics

150

204

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“…The observation by Japar et al 26 of acetone and formaldehyde, each with yields of 1.0, implies that reaction of the alkoxy radical OCH2C(OH)(CH3)2 with oxygen is negligible and does not compete with decomposition (reaction 22) under conditions relevant to the atmosphere.…”

Section: -Methyl-2-propanol (T-butyl Alcohol)mentioning

confidence: 96%

“…Perhaps surprisingly considering the current importance of alcohols in urban atmospheric chemistry, only a few studies have been carried out to characterize the products of the OH-alcohol reaction 14, [22][23][24][25][26] . Several of these laboratory studies have included the alcohol-chlorine atom reaction instead of, or in addition to, the alcohol-OH reaction (the two reactions involve similar mechanisms and lead to the same products, see reactions 1a and 1c).…”

Section: Product Studies and Reaction Mechanismsmentioning

confidence: 99%

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Atmospheric chemistry of alcohols

Grosjean¹

1997

J. Braz. Chem. Soc.

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A química atmosférica dos álcoois, os quais são largamente empregados como combustíveis de veículos leves (como o etanol no Brasil) e solventes industriais, foi revista com o foco centralizado em seus aspectos de cinética e mecanismos de reação. A oxidação dos álcoois na atmosfera envolve sua reação com radicais hidroxil (OH). São apresentadas constantes de velocidade para a reação álcool-OH de 33 álcoois saturados, incluindo compostos mono e difuncionais. As meias-vidas atmosféricas são, respectivamente, de uma semana para metanol e t-butil álcool, 2,5 dias para etanol, e de 8-15 h para outros álcoois. São descritos estudos de laboratório para os produtos de reações álcool-OH, e mecanismos são assinalados. Os produtos que predominam são o formaldeído para o metanol, acetaldeído para etanol, acetona para 2-propanol, 2-butanona e acetaldeído para o 2-butanol e acetona e formaldeído para o t-butil álcool.A reação de OH com os álcoois envolve a abstração de um átomo de hidrogênio da ligação C-H, ao passo que na ligação O-H esta abstração é negligível. Os radicais alquil (R) e α-hidroxialquil assim formados reagem então com oxigênio. Essa reação envolve adição para os radicais alquil (R + O2 → RO2) e abstração de H dos radicais α-hidroxialquil (ex. etanol + OH → CH3CHOH, CH3CHOH + O2 → HO2 + CH3CHO). A sequência de reações etanol → acetaldeído → nitrato de peroxiacetila (PAN, CH3C(O)OONO2) é descrita, sendo de grande relevância para a poluição atmosférica urbana no Brasil.Finalmente, recomenda-se que se façam estudos adicionais dos produtos, de maneira a desenvolver uma melhor compreensão da química atmosférica dos álcoois, e de seu papel na qualidade do ar urbano e regional.The atmospheric chemistry of alcohols, which are widely used as motor vehicle fuels (e.g. ethanol in Brazil) and as industrial solvents, has been reviewed with focus on kinetic data and on reaction mechanisms. Oxidation of alcohols in the atmosphere involves their reaction with the hydroxyl radical (OH). Alcohol-OH reaction rate constants are presented for 33 saturated alcohols including monofunctional and difunctional compounds. The corresponding atmospheric half-lives are one week for methanol and t-butyl alcohol, 2.5 days for ethanol, and 8-15 h for other alcohols. Laboratory studies of alcohol-OH reaction products are described and reaction mechanisms are outlined. Major products are formaldehyde from methanol, acetaldehyde from ethanol, acetone from 2-propanol, 2-butanone and acetaldehyde from 2-butanol and acetone and formaldehyde from t-butyl alcohol.The reaction of OH with alcohols involves H-atom abstraction from C-H bonds; H-atom abstraction from the O-H bond is negligible. The alkyl radicals (R) and α-hydroxyalkyl radicals thus formed react with oxygen. This reaction involves addition for alkyl radicals (R + O2 → RO2) and H-atom abstraction for α-hydroxyalkyl radicals (e.g. ethanol + OH → CH3CHOH, CH3CHOH + O2 → HO2 + CH3CHO). The reaction sequence ethanol → acetaldehyde → peroxyacetyl nitrate (PAN, CH3C(O)OONO2) is described and is r...

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“…The OH reaction kinetics and reaction products of some of these ethers and glycol ethers have been studied previously [11,12]. As indicated in reaction (3b), formation of organic nitrates is a termination step, which consumes peroxy radicals and NO x .…”

Section: Introductionmentioning

confidence: 99%

The production of organic nitrates from atmospheric oxidation of ethers and glycol ethers

Espada

Shepson

2005

Int J of Chemical Kinetics

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The production of organic nitrates from OH reaction (in the presence of NO) with methoxy propane, 1-methoxy-2-propanol, ethoxy butane, and 2-butoxyethanol was studied. The measured total organic nitrate yields were 1.8 (±0.4)%, 0.98 (±0.2)%, 7.7 (±2)%, and 9.6 (±1)%, respectively. The total organic nitrate yield for methoxypropane is 26% of that (7.0%) for n-butane. The organic nitrate yield for ethoxy butane is 55% of that (14%) for n-hexane. The peroxy radicals produced from OH reaction with the methylene groups α to the ether linkage have an organic nitrate branching ratio (k 3b /k 3 ) value ∼50% of those in analogous n-alkanes. On the other hand, k 3b /k 3 values for peroxy radical functional groups not adjacent to the ether linkage (in γ and δ positions) are on average 1.7 times greater than for the analogous n-alkyl peroxy radicals. The organic nitrate formation yield for 1-methoxy-2-propanol is almost half that of methoxy propane, while for 2-butoxyethanol it is 21% greater than that of butoxyethane. Our data lead us to the conclusion that the ether linkage imparts an inductive effect that decreases the value of k 3b /k 3 for peroxy radicals adjacent to it, yet has a stabilizing effect, from the additional vibrational modes for those peroxy radicals not adjacent to it, increasing their k 3b /k 3 values. The effect of both the O and OH groups in these molecules and the importance of their position relative to the peroxy group are discussed in this paper. C

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The atmospheric chemistry of Oxygenated fuel additives: t‐Butyl alcohol, dimethyl ether, and methylt‐butyl ether

Cited by 143 publications

References 14 publications

Methyl formate oxidation: Speciation data, laminar burning velocities, ignition delay times, and a validated chemical kinetic model

Methyl formate oxidation: Speciation data, laminar burning velocities, ignition delay times, and a validated chemical kinetic model

Atmospheric chemistry of alcohols

The production of organic nitrates from atmospheric oxidation of ethers and glycol ethers

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