Oxidation of dimethyl ether: Absolute rate constants for the self reaction of CH3OCH2 radicals, the reaction of CH3OCH2 radicals with O2, and the thermal decomposition of CH3OCH2 radicals

Jens Sehested; Knud Sehested; Iesper Platz; Helge Egsgaard; Ole John Nielsen

doi:10.1002/(SICI)1097-4601(1997)29:8<627::AID-KIN8>3.0.CO;2-W

Oxidation of dimethyl ether: Absolute rate constants for the self reaction of CH₃OCH₂ radicals, the reaction of CH₃OCH₂ radicals with O₂, and the thermal decomposition of CH₃OCH₂ radicals

Jens Sehested^*, Knud Sehested, Iesper Platz, Helge Egsgaard, Ole John Nielsen

^*Corresponding author af dette arbejde

52 Citationer (Scopus)

Abstract

The rate constant for the reaction of CH₃OCH₂ radicals with O₂ (reaction (1)) and the self reaction of CH₃OCH₂ radicals (reaction (5)) were measured using pulse radiolysis coupled with time resolved UV absorption spectroscopy. k₁ was studied at 296 K over the pressure range 0.025-1 bar and in the temperature range 296-473 K at 18 bar total pressure. Reaction (1) is known to proceed through the following mechanism: CH₃OCH₂ + O₂ ↔ CH₃OCH₂O₂^# → CH₂OCH₂O₂H^# → 2HCHO + OH (k_prod) CH₃OCH₂ + O₂ ↔ CH₃OCH₂O₂^# + M → CH₃OCH₂O₂ + M (k_RO2) k₁ = k_RO2 + k_prod, where k_RO2 is the rate constant for peroxy radical production and k_prod is the rate constant for formaldehyde production. The k₁ values obtained at 296 K together with the available literature values for k₁ determined at low pressures were fitted using a modified Lindemann mechanism and the following parameters were obtained: k_RO2,0 = (9.4 ± 4.2) × 10^-30 cm⁶ molecule^-2 s^-1, k_RO2,∞ = (1.14 ± 0.04) × 10^-11 cm³ molecule^-1 s^-1, and kprodi,0 = (6.0 ± 0.5) × 10^-12 cm³ molecule^-1 s^-1 where k_RO2,0 and k_RO2,∞ are the overall termolecular and bimolecular rate constants for formation of CH₃OCH₂O₂ radicals and k_prod,0 represents the bimolecular rate constant for the reaction of CH₃OCH₂ radicals with O₂ to yield formaldehyde in the limit of low pressure. k_RO2,∞ = (1.07 ± 0.08) × 10^-11 exp(-(46 ± 27)/T) cm³ molecule^-1 s^-1 was determined at 18 bar total pressure over the temperature range 296-473 K. At 1 bar total pressure and 296 K, k₃ = (4.1 ± 0.5) × 10^-11 cm³ molecule^-1 s^-1 and at 18 bar total pressure over the temperature range 296-523 K, k₅ = (4.7 ± 0.6) × 10^-11 cm³ molecule^-1 s^-1. As a part of this study the decay rate of CH₃OCH₂ radicals was used to study the thermal decomposition of CH₃OCH₂ radicals in the temperature range 573-666 K at 18 bar total pressure. The observed decay rates of CH₃OCH₂ radicals were consistent with the literature value of k₂ = 1.6 × 10¹³exp(-12800/T) s^-1. The results are discussed in the context of dimethyl ether as an alternative diesel fuel.

Originalsprog	Engelsk
Tidsskrift	International Journal of Chemical Kinetics
Vol/bind	29
Udgave nummer	8
Sider (fra-til)	627-636
Antal sider	10
ISSN	0538-8066
DOI	https://doi.org/10.1002/(SICI)1097-4601(1997)29:8<627::AID-KIN8>3.0.CO;2-W
Status	Udgivet - 1 jan. 1997

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10.1002/(SICI)1097-4601(1997)29:8<627::AID-KIN8>3.0.CO;2-W

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Citationsformater

Sehested, J., Sehested, K., Platz, I., Egsgaard, H., & Nielsen, O. J. (1997). Oxidation of dimethyl ether: Absolute rate constants for the self reaction of CH₃OCH₂ radicals, the reaction of CH₃OCH₂ radicals with O₂, and the thermal decomposition of CH₃OCH₂ radicals. International Journal of Chemical Kinetics, 29(8), 627-636. https://doi.org/10.1002/(SICI)1097-4601(1997)29:8<627::AID-KIN8>3.0.CO;2-W

Oxidation of dimethyl ether : Absolute rate constants for the self reaction of CH₃OCH₂ radicals, the reaction of CH₃OCH₂ radicals with O₂, and the thermal decomposition of CH₃OCH₂ radicals. / Sehested, Jens; Sehested, Knud; Platz, Iesper et al.

I: International Journal of Chemical Kinetics, Bind 29, Nr. 8, 01.01.1997, s. 627-636.

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review

Sehested, J, Sehested, K, Platz, I, Egsgaard, H & Nielsen, OJ 1997, 'Oxidation of dimethyl ether: Absolute rate constants for the self reaction of CH₃OCH₂ radicals, the reaction of CH₃OCH₂ radicals with O₂, and the thermal decomposition of CH₃OCH₂ radicals', International Journal of Chemical Kinetics, bind 29, nr. 8, s. 627-636. https://doi.org/10.1002/(SICI)1097-4601(1997)29:8<627::AID-KIN8>3.0.CO;2-W

Sehested J, Sehested K, Platz I, Egsgaard H, Nielsen OJ. Oxidation of dimethyl ether: Absolute rate constants for the self reaction of CH₃OCH₂ radicals, the reaction of CH₃OCH₂ radicals with O₂, and the thermal decomposition of CH₃OCH₂ radicals. International Journal of Chemical Kinetics. 1997 jan. 1;29(8):627-636. doi: 10.1002/(SICI)1097-4601(1997)29:8<627::AID-KIN8>3.0.CO;2-W

@article{e69fdb73fcb7459a9e4fe0b3d77897c5,

title = "Oxidation of dimethyl ether: Absolute rate constants for the self reaction of CH3OCH2 radicals, the reaction of CH3OCH2 radicals with O2, and the thermal decomposition of CH3OCH2 radicals",

abstract = "The rate constant for the reaction of CH3OCH2 radicals with O2 (reaction (1)) and the self reaction of CH3OCH2 radicals (reaction (5)) were measured using pulse radiolysis coupled with time resolved UV absorption spectroscopy. k1 was studied at 296 K over the pressure range 0.025-1 bar and in the temperature range 296-473 K at 18 bar total pressure. Reaction (1) is known to proceed through the following mechanism: CH3OCH2 + O2 ↔ CH3OCH2O2# → CH2OCH2O2H# → 2HCHO + OH (kprod) CH3OCH2 + O2 ↔ CH3OCH2O2# + M → CH3OCH2O2 + M (kRO2) k1 = kRO2 + kprod, where kRO2 is the rate constant for peroxy radical production and kprod is the rate constant for formaldehyde production. The k1 values obtained at 296 K together with the available literature values for k1 determined at low pressures were fitted using a modified Lindemann mechanism and the following parameters were obtained: kRO2,0 = (9.4 ± 4.2) × 10-30 cm6 molecule-2 s-1, kRO2,∞ = (1.14 ± 0.04) × 10-11 cm3 molecule-1 s-1, and kprodi,0 = (6.0 ± 0.5) × 10-12 cm3 molecule-1 s-1 where kRO2,0 and kRO2,∞ are the overall termolecular and bimolecular rate constants for formation of CH3OCH2O2 radicals and kprod,0 represents the bimolecular rate constant for the reaction of CH3OCH2 radicals with O2 to yield formaldehyde in the limit of low pressure. kRO2,∞ = (1.07 ± 0.08) × 10-11 exp(-(46 ± 27)/T) cm3 molecule-1 s-1 was determined at 18 bar total pressure over the temperature range 296-473 K. At 1 bar total pressure and 296 K, k3 = (4.1 ± 0.5) × 10-11 cm3 molecule-1 s-1 and at 18 bar total pressure over the temperature range 296-523 K, k5 = (4.7 ± 0.6) × 10-11 cm3 molecule-1 s-1. As a part of this study the decay rate of CH3OCH2 radicals was used to study the thermal decomposition of CH3OCH2 radicals in the temperature range 573-666 K at 18 bar total pressure. The observed decay rates of CH3OCH2 radicals were consistent with the literature value of k2 = 1.6 × 1013exp(-12800/T) s-1. The results are discussed in the context of dimethyl ether as an alternative diesel fuel.",

author = "Jens Sehested and Knud Sehested and Iesper Platz and Helge Egsgaard and Nielsen, {Ole John}",

year = "1997",

month = jan,

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doi = "10.1002/(SICI)1097-4601(1997)29:8<627::AID-KIN8>3.0.CO;2-W",

language = "English",

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journal = "International Journal of Chemical Kinetics",

issn = "0538-8066",

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TY - JOUR

T1 - Oxidation of dimethyl ether

T2 - Absolute rate constants for the self reaction of CH3OCH2 radicals, the reaction of CH3OCH2 radicals with O2, and the thermal decomposition of CH3OCH2 radicals

AU - Sehested, Jens

AU - Sehested, Knud

AU - Platz, Iesper

AU - Egsgaard, Helge

AU - Nielsen, Ole John

PY - 1997/1/1

Y1 - 1997/1/1

N2 - The rate constant for the reaction of CH3OCH2 radicals with O2 (reaction (1)) and the self reaction of CH3OCH2 radicals (reaction (5)) were measured using pulse radiolysis coupled with time resolved UV absorption spectroscopy. k1 was studied at 296 K over the pressure range 0.025-1 bar and in the temperature range 296-473 K at 18 bar total pressure. Reaction (1) is known to proceed through the following mechanism: CH3OCH2 + O2 ↔ CH3OCH2O2# → CH2OCH2O2H# → 2HCHO + OH (kprod) CH3OCH2 + O2 ↔ CH3OCH2O2# + M → CH3OCH2O2 + M (kRO2) k1 = kRO2 + kprod, where kRO2 is the rate constant for peroxy radical production and kprod is the rate constant for formaldehyde production. The k1 values obtained at 296 K together with the available literature values for k1 determined at low pressures were fitted using a modified Lindemann mechanism and the following parameters were obtained: kRO2,0 = (9.4 ± 4.2) × 10-30 cm6 molecule-2 s-1, kRO2,∞ = (1.14 ± 0.04) × 10-11 cm3 molecule-1 s-1, and kprodi,0 = (6.0 ± 0.5) × 10-12 cm3 molecule-1 s-1 where kRO2,0 and kRO2,∞ are the overall termolecular and bimolecular rate constants for formation of CH3OCH2O2 radicals and kprod,0 represents the bimolecular rate constant for the reaction of CH3OCH2 radicals with O2 to yield formaldehyde in the limit of low pressure. kRO2,∞ = (1.07 ± 0.08) × 10-11 exp(-(46 ± 27)/T) cm3 molecule-1 s-1 was determined at 18 bar total pressure over the temperature range 296-473 K. At 1 bar total pressure and 296 K, k3 = (4.1 ± 0.5) × 10-11 cm3 molecule-1 s-1 and at 18 bar total pressure over the temperature range 296-523 K, k5 = (4.7 ± 0.6) × 10-11 cm3 molecule-1 s-1. As a part of this study the decay rate of CH3OCH2 radicals was used to study the thermal decomposition of CH3OCH2 radicals in the temperature range 573-666 K at 18 bar total pressure. The observed decay rates of CH3OCH2 radicals were consistent with the literature value of k2 = 1.6 × 1013exp(-12800/T) s-1. The results are discussed in the context of dimethyl ether as an alternative diesel fuel.

AB - The rate constant for the reaction of CH3OCH2 radicals with O2 (reaction (1)) and the self reaction of CH3OCH2 radicals (reaction (5)) were measured using pulse radiolysis coupled with time resolved UV absorption spectroscopy. k1 was studied at 296 K over the pressure range 0.025-1 bar and in the temperature range 296-473 K at 18 bar total pressure. Reaction (1) is known to proceed through the following mechanism: CH3OCH2 + O2 ↔ CH3OCH2O2# → CH2OCH2O2H# → 2HCHO + OH (kprod) CH3OCH2 + O2 ↔ CH3OCH2O2# + M → CH3OCH2O2 + M (kRO2) k1 = kRO2 + kprod, where kRO2 is the rate constant for peroxy radical production and kprod is the rate constant for formaldehyde production. The k1 values obtained at 296 K together with the available literature values for k1 determined at low pressures were fitted using a modified Lindemann mechanism and the following parameters were obtained: kRO2,0 = (9.4 ± 4.2) × 10-30 cm6 molecule-2 s-1, kRO2,∞ = (1.14 ± 0.04) × 10-11 cm3 molecule-1 s-1, and kprodi,0 = (6.0 ± 0.5) × 10-12 cm3 molecule-1 s-1 where kRO2,0 and kRO2,∞ are the overall termolecular and bimolecular rate constants for formation of CH3OCH2O2 radicals and kprod,0 represents the bimolecular rate constant for the reaction of CH3OCH2 radicals with O2 to yield formaldehyde in the limit of low pressure. kRO2,∞ = (1.07 ± 0.08) × 10-11 exp(-(46 ± 27)/T) cm3 molecule-1 s-1 was determined at 18 bar total pressure over the temperature range 296-473 K. At 1 bar total pressure and 296 K, k3 = (4.1 ± 0.5) × 10-11 cm3 molecule-1 s-1 and at 18 bar total pressure over the temperature range 296-523 K, k5 = (4.7 ± 0.6) × 10-11 cm3 molecule-1 s-1. As a part of this study the decay rate of CH3OCH2 radicals was used to study the thermal decomposition of CH3OCH2 radicals in the temperature range 573-666 K at 18 bar total pressure. The observed decay rates of CH3OCH2 radicals were consistent with the literature value of k2 = 1.6 × 1013exp(-12800/T) s-1. The results are discussed in the context of dimethyl ether as an alternative diesel fuel.

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