Knock resistance and anti-knock with hydrocarbon fuels

Cartlidge, J.; Tipper, C. F. H.

doi:10.1016/0010-2180(61)90078-5

Cited by 30 publications

(8 citation statements)

References 11 publications

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“…Hydroperoxides are probably important as the degenerate branching intermediate below about 300" while aldehydes are more important above this temperature. 29 In the oxidation of ethane, acetaldehyde is only a trace product and the low catalytic activity of added acetaldehyde rules it out as the major autocatalyst at 362". Ethylene oxide, a possible autocatalyst in the ethylene oxidation above 400°,31 is not a catalyst in the ethane oxidation at 362" as shown by its negligible effect on the acceleration constant when added in substantial quantity.…”

Section: Discussionmentioning

confidence: 99%

Slow oxidation of ethane and ethylene in the gas phase. Part 1.—General features at 362°C

Knox¹,

Wells²

1963

Trans. Faraday Soc.

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The kinetic and analytical features of the oxidation of ethane and ethylene at 362" are described.In the early stages of the oxidation of ethane, 80 % of the hydrocarbon consumed gives ethylene.In the intermediate stages the ethylene is itself oxidized. In the initial stages of the oxidation of pure ethylene over 80 % of the hydrocarbon consumed gives formaldehyde, and in the intermediate stages the formaldehyde is oxidized to carbon monoxide. The main molecular stages in the oxidation are therefore ethane, ethylene, formaldehyde, carbon monoxide, with water also being formed at the appropriate stages.The kinetics of the ethane oxidation are similar to those of the propane oxidation and the autocatalysis of the reaction is probably due to the oxidation of formaldehyde. The slow start of the acceleration is in part due to the fact that the branching intermediate is not an initial product of the reaction.The general nature of hydrocarbon oxidation reactions is discussed. It is concluded that the main reaction of alkyl radicals with oxygen at 300-400" is usually an abstraction reaction However, there is strong evidence that the H02 radical is unable to abstract H from ethane or most other hydrocarbons, and it is proposed that a key reaction in alkane oxidation is the conversion of HO2 to OH. The reaction 2H02 = 20H+02 is suggested.CnH2n+1+ 0 2 = CnH2n+ HO2.

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Section: Discussionmentioning

confidence: 99%

Slow oxidation of ethane and ethylene in the gas phase. Part 1.—General features at 362°C

Knox¹,

Wells²

1963

Trans. Faraday Soc.

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“…This scheme dating back to the mid 20th century [7,8] laid the foundation for the first mathematical models for predicting ignition [13,25]. At present, the scheme remains largely unchanged in high fidelity chemical kinetic simulations used to improve the efficiency and emissions of combustion systems [11,[26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

“…The auto-oxidation process begins with radical initiation and proceeds by a series of O 2 addition and intramolecular H-atom migration reactions that eventually lead to radical chain-branching, propagation, or termination [7][8][9][10][11][12], as presented in Scheme 1 (see Supporting Information, SI, for detailed description). This scheme dating back to the mid 20th century [7,8] laid the foundation for the first mathematical models for predicting ignition [13,25].…”

Section: Introductionmentioning

confidence: 99%

Additional chain-branching pathways in the low-temperature oxidation of branched alkanes

Wang

Zhang

Moshammer

et al. 2016

Combustion and Flame

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a b s t r a c tChain-branching reactions represent a general motif in chemistry, encountered in atmospheric chemistry, combustion, polymerization, and photochemistry; the nature and amount of radicals generated by chainbranching are decisive for the reaction progress, its energy signature, and the time towards its completion. In this study, experimental evidence for two new types of chain-branching reactions is presented, based upon detection of highly oxidized multifunctional molecules (HOM) formed during the gas-phase low-temperature oxidation of a branched alkane under conditions relevant to combustion. The oxidation of 2,5-dimethylhexane (DMH) in a jet-stirred reactor (JSR) was studied using synchrotron vacuum ultraviolet photoionization molecular beam mass spectrometry (SVUV-PI-MBMS). Specifically, species with four and five oxygen atoms were probed, having molecular formulas of C 8 H 14 O 4 (e.g., diketo-hydroperoxide/ketohydroperoxy cyclic ether) and C 8 H 16 O 5 (e.g., keto-dihydroperoxide/dihydroperoxy cyclic ether), respectively. The formation of C 8 H 16 O 5 species involves alternative isomerization of OOQOOH radicals via intramolecular H-atom migration, followed by third O 2 addition, intramolecular isomerization, and OH release; C 8 H 14 O 4 species are proposed to result from subsequent reactions of C 8 H 16 O 5 species. The mechanistic pathways involving these species are related to those proposed as a source of low-volatility highly oxygenated species in Earth's troposphere. At the higher temperatures relevant to auto-ignition, they can result in a net increase of hydroxyl radical production, so these are additional radical chain-branching pathways for ignition. The results presented herein extend the conceptual basis of reaction mechanisms used to predict the reaction behavior of ignition, and have implications on atmospheric gas-phase chemistry and the oxidative stability of organic substances.

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“…It is interesting to note that the hydrocarbons (propane and triptane), which oxidize readily only at relatively high temperatures, did not give hydroperoxides, the hydrocarbons (w-butane and cyc/ohexane), which oxidize moderately readily, yield mainly monohydroperoxides, and ^-heptane, which oxidizes at relatively low temperatures, gives mainly dihydroperoxides. The bearing of this on the knock ratings of hydrocarbon fuels has been discussed recently by the authors (Cartlidge & Tipper 1961).…”

Section: I O O C H 2o H O •mentioning

confidence: 96%

The peroxides formed during hydrocarbon slow combustion and their role in the mechanism

Cartlidge

Tipper

1961

Proc. R. Soc. Lond. A

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The peroxides formed during the slow combustion of five hydrocarbons in a flow system have been identified and the approximate yields estimated. With propane at 327°C and 2, 2, 3-trimethylbutane at 365 to 385°C the products contained only traces of hydrogen peroxide, its addition compounds with aldehyde and (with C 3 H 8 ) peracetic acid. With n -butane between 310 and 345°C and cylohexane between 290 and 316°C appreciable yields of peroxide were obtained (~ 10 to 20% of the hydrocarbon oxidized). These consisted of the monohydroperoxides, hydrogen peroxide and their addition compounds with aldehydes. With n -C 4 H 10 the relative amount of H 2 O 2 free and combined ( ~ 50% of the total peroxide yield) was much higher than with C 6 H 12 and some perpropionic acid was also detected. With n -heptane between 240 and 310°C the yield of peroxide in the products was also con siderable ( ~ 20% of the hydrocarbon reacted), and consisted mainly of dihydroperoxyheptane and its addition compounds with aldehydes (mainly formaldehyde), with much smaller amounts of monohydroperoxide and hydrogen peroxide (free and combined with aldehyde), diheptylperoxide and possible trihydroperoxyheptane. Packing the vessel increased the relative amount of aldehyde-addition compounds but did not affect the yield of free aldehyde, which apparently depended only on the temperature, being zero at 240°C. All aldehydes up to C 5 H 11 CHO were formed at higher temperatures, but those from C 3 to C 6 only in small yield. A little β -dicarbonyl compound and carboxylic acids were also detected in the products. The modes of formation and decomposition of the peroxides is discussed. It is suggested the dihydroperoxyheptane resulted from the abstraction of a hydrogen atom internally in the C 7 H 15 O 2 radical from the CH 2 group β or γ to the point of original attack, that aldehydes were produced partly by heterogeneous hydroperoxide decomposition and partly by decomposition of RO 2 radicals, and that with n -heptane the aldehyde-hydroperoxide compounds were formed mainly on the walls of the reaction vessel. Chain branching in the oxidation of propane and 2, 2, 3-trimethylbutane was presumably due exclusively to the oxidation of aldehydes formed, whereas with the other three hydrocarbons branching due to homogeneous peroxide decomposition was probably important up to about 350°C.

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Knock resistance and anti-knock with hydrocarbon fuels

Cited by 30 publications

References 11 publications

Slow oxidation of ethane and ethylene in the gas phase. Part 1.—General features at 362°C

Slow oxidation of ethane and ethylene in the gas phase. Part 1.—General features at 362°C

Additional chain-branching pathways in the low-temperature oxidation of branched alkanes

The peroxides formed during hydrocarbon slow combustion and their role in the mechanism

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