experimental and modeling study of the kinetics of oxidation of butanol− n- ...

Experimental and Modeling Study of the Kinetics of Oxidation ofButanol-n-Heptane Mixtures in a Jet-stirred Reactor

Philippe Dagaut* and Casimir Togbe

CNRS, 1c, AVenue de la Recherche Scientifique, 45071 Orleans cedex 2, France

ReceiVed March 25, 2009. ReVised Manuscript ReceiVed May 14, 2009

The kinetics of oxidation of 1-butanol/n-heptane mixtures (20/80 and 50/50 in mol) was studied experimentallyusing a fused silica jet-stirred reactor. The experiments were performed in the temperature range 530-1070K, at 10 atm, at two equivalence ratios (0.5 and 1), and with an initial fuel concentration of 750 ppm. Akinetic modeling was performed using reaction mechanisms resulting from the merging of validated kineticschemes for the oxidation of the components of the present mixtures (n-heptane and butanol). Good agreementbetween the experimental results and the computations was observed under the present conditions when usingdetailed chemistry, whereas using semidetailed chemistry yielded a less-accurate prediction of the fuel oxidationkinetics.

1. Introduction

The worldwide increase of CO2 and pollutants emissions fromground transportation vehicles using fossil fuels is a majorconcern.1-4 But, during the last two decades the incorporationof nonfossil compounds in automotive fuels to reduce carbonfootprint has increased,5 and mixtures of petrol gasoline with avariety of oxygenates are used worldwide.6 Among these,ethanol has become a major gasoline component, whereas itsincreasing use is also source of concerns since engine exhaustscontaining relatively large amounts of ethanol and acetaldehydemay be very harmful.7-13 In this context, biobutanol (1-butanol)was recently proposed to be blended with gasoline, in part forits higher energy content (26.9-27.0 MJ/L) than ethanol(21.1-21.7 MJ/L) and its low vapor pressure (Reid values of

0.33 psi for 1-butanol, 2 psi for ethanol, and 4.5 psi forgasoline).14 Furthermore, many recent publications15-18 concernthe production of biobutanol by advanced fermentation tech-niques. However, only few studies concern the oxidation/combustion of 1-butanol: engine tests were performed,19-22

stoichiometric CH4 non-premixed atmospheric flames dopedwith four butanol isomers have been investigated,23 and thestructures of rich butanol isomers low-pressure premixed flames(� ) 1.71, 30 torr, i.e., 4 kPa) have been studied.24 Unfortu-nately, these experiments did not provide directly usable datafor kinetic modeling. Recently, few kinetic studies providingexperimental data and chemical kinetic schemes were pub-lished,25-28 but new inputs into experimental databases werestill needed to propose and validate chemical kinetic modelsfor the combustion of 1-butanol blended fuel mixtures.

As part of a continuing laboratory effort to improve theknowledge of fuel combustion kinetics and provide the neededinputs for future modeling, we (i) performed experiments on

* Corresponding author: phone: +(33) 238 25 54 66: fax: +(33) 238 6960 04: e-mail: [email protected].

(1) Barker, T., Bashmakov, I., Bernstein, L., Bogner, J. E., Bosch, P. R.,Dave, R., Davidson, O. R., Fisher, B. S., Gupta, S., Halsnæs, K., Heij,G. J., Kahn Ribeiro, S. Kobayashi, S., Levine, M. D., Martino, D. L., Masera,O., Metz, B., Meyer, L. A., Nabuurs, G.-J., Najam, A., Nakicenovic, N.,Rogner, H.-H., Roy, J., Sathaye, J., Schock, R., Shukla, P., Sims, R. E. H.,Smith, P., Tirpak, D. A., Urge-Vorsatz, D., Zhou, D. Technical Summary.In: Climate Change 2007: Mitigation. Contribution of Working Group IIIto the Fourth Assessment Report of the IntergoVernmental Panel on ClimateChange; Cambridge University Press: Cambridge, United Kingdom and NewYork, NY, USA: 2007.

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Sonomoto, K. J. Biosci. Bioeng. 2007, 104 (3), 238–240.(16) Ezeji, T. C.; Qureshi, N.; Blaschek, H. P. Curr. Opin. Biotechnol.

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214 (A5), 497–511.(22) Gautam, M.; Martin, D. W.; Carder, D. Proc. Inst. Mech. Eng.,

Part A 2000, 214 (A2), 165–182.(23) McEnally, C. S.; Pfefferle, L. D. Proc. Combust. Inst. 2005, 30,

1363–1370.(24) Yang, B.; Osswald, P.; Li, Y. Y.; Wang, J.; Wei, L. X.; Tian, Z. Y.;

Qi, F.; Kohse-Hoinghaus, K. Combust. Flame 2007, 148 (4), 198–209.(25) Dagaut, P.; Togbe, C. Fuel 2008, 87 (15-16), 3313–3321.(26) Dagaut, P.; Sarathy, S. M.; Thomson, M. J. Proc. Combust. Inst.

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Energy & Fuels 2009, 23, 3527–3535 3527

10.1021/ef900261f CCC: $40.75 2009 American Chemical SocietyPublished on Web 06/11/2009

the oxidation of 1-butanol blended fuels in a jet-stirred reactor(JSR) and (ii) proposed a kinetic model representing the data.Since several kinetic schemes for n-heptane oxidation areavailable in the literature, two of them (a detailed scheme29 anda derived reduce scheme30) were used and merged with apreviously used kinetic subscheme for the oxidation of 1-butanoland its mixture with a surrogate gasoline.25 The experimentaland modeling results obtained in the present study are reportedin the next sections.

2. Experimental Section

A fused-silica spherical JSR similar to that used previously31

and operating up to 10 atm was used. It was located inside aregulated electrical resistance oven of ≈1.5 kW itself surroundedby insulating ceramic wool and a stainless steel pressure-resistantjacket. 1-Butanol (99% pure, Aldrich) and n-heptane (>99% pure,Aldrich) were mixed after thorough ultrasonic degassing. The liquidfuel mixture was pumped, using a micropiston HPLC pump(Shimadzu LC-120 ADvp) and an online degasser (Shimadzu DGU-20 A3), and sent to an in-house stainless steel atomizer-vaporizerassembly maintained at 175 °C. A flow of nitrogen (50 L/h) wasused for the atomization. The oxygen (99.995% pure) flow wasdiluted by a flow of nitrogen (<50 ppm of O2; <1000 ppm of Ar;<5 ppm of H2). This oxygen-nitrogen flow was mixed with thefuel-nitrogen flow just before the entrance of the injectors, afterpreheating. All the gases were regulated by thermal mass-flowcontrollers (Brooks 5850E). Residence time distribution studiesshowed that under the conditions of the present study the reactoris operating under macro-mixing conditions.31 As in previouswork,31,32 thermocouple measurements (0.1 mm diameter Pt/Pt-Rh10% located inside a thin-wall fused-silica tube to prevent catalyticreactions on the wires) showed good thermal homogeneity alongthe vertical axis of the reactor. Typical temperature gradients ofless than ca. 2 K/cm were measured. Since the experiments wereperformed under high dilution, the temperature rise due to thereaction was generally less than ca. 30 K. Low-pressure samplesof the reacting mixtures were taken by sonic probe sampling andcollected in 1 L Pyrex bulbs at ca. 40 mBar for immediate gaschromatography (GC) analyses as in refs 32 and 33.

For the measurements of hydrocarbons and oxygenates, capillarycolumns of 0.32 mm i.d. (DB-624, 50m and Al2O3/KCl 50m) wereused with a flame ionization detector (FID) and helium as carriergas. Hydrogen and oxygen were measured using a 0.53 mm i.d.capillary column (Carboplot, 25 m) fitted to a thermal conductivitydetector. Nitrogen was used as carrier gas. Online Fourier transforminfrared (FTIR) analyses of the reacting gases were also performedby connecting the sampling probe to a temperature-controlled gascell (140 °C, 10 m path length, 0.5 cm-1 resolution) via a Teflonheated line maintained at 175 °C. The sample pressure in the cellwas 0.2 bar. This analytical equipment allowed the measurementsof oxygen, hydrogen, 1-butanol, n-heptane, methane, ethane,ethylene, acetylene, propene, 1-butene, 1-pentene, 1-hexene, butanal,ethanal, CH2O, CO, CO2, and H2O, as previously,32 very goodagreement between the GC and FTIR analyses was found for the

compounds measured by both techniques. Carbon balance waschecked for every sample and was found to be typically good (100( 8%).

3. Kinetic Modeling

The modeling was performed using the PSR computer code.34

We used kinetic reaction mechanisms obtained by merging a1-butanol oxidation subscheme25 and two literature schemes forthe oxidation of n-heptane:29,30,35 a detailed scheme29,35 and areduced version30 of the initial n-heptane oxidation scheme29

were used here. To reduce the mechanism, the authors used a2-steps procedure where a truncated scheme was obtained firstand further reduced. The truncated scheme resulted from theelimination of unimportant species for ignition predictions(deviation <0.84%), and their associated reactions ignition. Thereduced mechanism was obtained by removing species notimportant for flame computations. This yielded a reducedmechanism involving 770 reversible reactions among 159species. A list of the discarded species is provided as SupportingInformation. The butanol-heptane semidetailed and detailedschemes involved, respectively, 181 species and 1703 reactionsand 573 species and 2701 reactions. The rate constants for thereverse reactions were computed from the forward rate constantsand the appropriate equilibrium constants calculated usingthermochemical data.25,29,30,36 The two mechanisms used here,including thermochemical data, are available from the authorsand as Supporting Information. To rationalize the results,reaction rates analyses were performed by computing the ratesof consumption (R with a negative sign) and production (R witha positive sign) for every species.

4. Results and Discussion

In this work, the oxidation of two 1-butanol-heptane mixtures(20/80 and 50/50 mol %) was studied. The composition of thereacting mixtures is given in Table 1. The oxidation of thesemixtures was performed in a JSR at a fixed residence time of0.7 s and at 10 atm. During the JSR experiments, 17 specieswere identified and measured by GC/MS, FID, and TCD.Experimental mole fractions as a function of temperature wereobtained for H2, H2O, O2, CO, CO2, CH2O, CH4, C2H6, C2H4,C2H2, acetaldehyde (ethanal), C3H6, 1-butanol, butanal, 1-C4H8,1-C5H10, and 1-C6H12. No new species resulting from theinteractions of the two fuels or their specific fragments couldbe observed

The experimental data were used to compute the rates ofconsumption of 1-butanol and n-heptane over the cool-flameregime (ca. 530-770 K), the negative temperature coefficientwhere the rate of consumption of the fuel decreases withincreasing temperature (ca. 620-770 K), and the intermediate

(29) Curran, H. J.; Gaffuri, P.; Pitz, W. J.; Westbrook, C. K. Combust.Flame 1998, 114 (1-2), 149–177.

(30) Seiser, R.; Pitsch, H.; Seshadri, K.; Pitz, W. J.; Curran, H. J. Proc.Combust. Inst. 2000, 28, 2029–2037.

(31) Dagaut, P.; Cathonnet, M.; Rouan, J. P.; Foulatier, R.; Quilgars,A.; Boettner, J. C.; Gaillard, F.; James, H. J. Phys. E 1986, 19 (3), 207–209.

(32) Dayma, G.; Hadj Ali, K.; Dagaut, P. Proc. Combust. Inst. 2007,31 (1), 411–418.

(33) Dubreuil, A.; Foucher, F.; Mounaim-Rousselle, C.; Dayma, G.;Dagaut, P. Proc. Combust. Inst. 2007, 31 (2), 2879–2886.

(34) Glarborg, P.; Kee, R. J.; Grcar, J. F.; Miller, J. A. PSR: A FORTRANProgram for Modeling Well-stirred Reactors; SAND86-8209; SandiaNational Laboratories: Livermore, CA, 1986.

(35) Curran, H. J.; Gaffuri, P.; Pitz, W. J.; Westbrook, C. K. Combust.Flame 2002, 129 (3), 253–280.

(36) Tan, Y.; Dagaut, P.; Cathonnet, M.; Boettner, J. C. Combust. Sci.Technol. 1994, 102 (1-6), 21–55.

Table 1. Experimental Conditions

initial mole fractions1-butanol-heptane

(mol %)equivalence

ratio 1-butanol n-heptane oxygen

20/80 0.5 1.50 × 10-4 6.00 × 10-4 1.500 × 10-2

20/80 1 1.50 × 10-4 6.00 × 10-4 7.50 × 10-3

50/50 0.5 3.75 × 10-4 3.75 × 10-4 1.275 × 10-2

50/50 1 3.75 × 10-4 3.75 × 10-4 6.375 × 10-3

3528 Energy & Fuels, Vol. 23, 2009 Dagaut and Togbe

and high-temperature oxidation regimes (>770 K). It should benoted at this stage that in absence of n-heptane, 1-butanol wouldnot oxidize below ca. 770 K (cool-flame regime) under JSRconditions similar to those of the present study. Figure 1 showsthe rates of consumption of 1-butanol and n-heptane are verysimilar when these two components have the same initial molefraction in the fuel, whereas in the case of the 1-butanol/heptane20/80 mol % mixture, the rate of consumption of n-heptane isca. 4 times higher than that of 1-butanol, in line with theirrespective initial concentrations in the fuel. Figures 2-9compare the present experimental results to the computations.It can be noticed from Figures 2-5 that the semidetailed modeldoes not accurately represent the mole fractions of the fuelcomponents and of the main products. The model is predicting

too fast the formation of CO, CO2, and H2O above 800 K.Actually, the reduced mechanism30 used here was proposed forautoignition studies in a counter-flow flame configuration, thatis, at temperatures above 1000 K, which did not allow testingof its capability to reproduce experimental results obtained atlow temperatures and high pressures where the role of peroxidesis important, as in this work. Therefore, these modeling resultscould have been expected since the semidetailed low-temper-ature chemistry is less accurate than in the detailed scheme.The present computations indicated that the only species notincluded in the reduced scheme with concentrations higher than1 ppm were C2H4O1-2, bC5H10, C2H5O2H, nC3H7O2H,CH3CO3H, CH3COCH2O2H, and nC3H7COCH3. However, other

Figure 1. The experimental rates of oxidation of 1-butanol and n-heptane during the oxidation of the 1-butanol/heptane 20/80 and 50/50 (mol %)fuel mixtures in a JSR at 10 atm, 700 ms, and � ) 1.

Figure 2. The oxidation of a 1-butanol/heptane 20/80 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 0.5. Comparison between experimentalresults (symbols) and semidetailed modeling (lines and small symbols).

Figure 3. The oxidation of a 1-butanol/heptane 20/80 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 1. Comparison between experimentalresults (symbols) and semidetailed modeling (lines and small symbols).

Oxidation of Butanol-Heptane Energy & Fuels, Vol. 23, 2009 3529

Figure 6. The oxidation of a 1-butanol/heptane 20/80 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 0.5. Comparison between experimentalresults (symbols) and detailed modeling (lines and small symbols).

Figure 4. The oxidation of a 1-butanol/heptane 50/50 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 0.5. Comparison between experimentalresults (symbols) and semidetailed modeling (lines and small symbols).

Figure 5. The oxidation of a 1-butanol/heptane 50/50 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 1. Comparison between experimentalresults (symbols) and semidetailed modeling (lines and small symbols).


C4 and C5 species not considered in the reduced scheme couldalso affect the model predictions.

Figures 6-9 present comparisons between the presentexperimental data and the simulations using the detailed scheme.

Figure 7. The oxidation of a 1-butanol/heptane 20/80 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 1. Comparison between experimentalresults (symbols) and detailed modeling (lines and small symbols).

Figure 8. The oxidation of a 1-butanol/heptane 50/50 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 0.5. Comparison between experimentalresults (symbols) and detailed modeling (lines and small symbols).


As can be seen from these figures, the model represents wellthe consumption of the fuels as well as the intermediateformation of hydrocarbons and oxygenates and that of finalproducts. The model is predicting very well the mole fractionsof CO, CO2, and H2O above 800 K.

Therefore, reaction paths analyses, using the detailed chemicalscheme, were performed to delineate the main oxidation reactionpaths of the fuel. Normalized rates of production (R with a positivesign) and consumption (R with a negative sign) were computedfor every species. For the 20/80 1-butanol/heptane fuel mixture,in stoichiometric conditions and low temperature (640 K), n-hep-tane mostly reacts by H-atom abstraction with OH:

1-Butanol also reacts predominantly with OH:

Butanal is mostly formed from through the oxidation ofn-heptane whereas the route through 1-butanol contributes ca.2% to its formation:

Ethylene formation mostly proceeds through the oxidation of n-heptaneand the intermediate formation and oxidation of ethyl radicals:

Figure 9. The oxidation of a 1-butanol/heptane 50/50 mol % fuel mixture in a JSR at 10 atm, 700 ms, and � ) 1. Comparison between experimentalresults (symbols) and detailed modeling (lines and small symbols).

2107. nC7H16 + OHS C7H15 - 1 + H2O;

R(nC7H16) ) -0.16

2108. nC7H16 + OHS C7H15 - 2 + H2O;

R(nC7H16) ) -0.32

2109. nC7H16 + OHS C7H15 - 3 + H2O;

R(nC7H16) ) -0.32

2110. nC7H16 + OHS C7H15 - 4 + H2O;

R(nC7H16) ) -0.16

2629. C4H9OH + OH ⇒ H2O + aC4H8OH;

R(C4H9OH) ) -0.22

2630. C4H9OH + OH ⇒ H2O + pC4H9O;

R(C4H9OH) ) -0.222

2631. C4H9OH + OH ⇒ H2O + dC4H8OH;

R(C4H9OH) ) -0.088

2632. C4H9OH + OH ⇒ H2O + cC4H8OH;

R(C4H9OH) ) -0.22

2633. C4H9OH + OH ⇒ H2O + C4H8OH - 1;

R(C4H9OH) ) -0.22

2038.nC4KET13S nC3H7CHO + CH2CHO + OH;

R(butanal) ) 0.018

2274. C7H15O-4S nC3H7CHO + nC3H7; R(butanal) ) 0.03

2342. nC7KET14S nC3H7CHO + CH2CH2CHO + OH;

R(butanal) ) 0.013

2346. nC7KET24S nC3H7CHO + CH3COCH2 + OH;

R(butanal) ) 0.877

2351. nC7KET34S nC3H7CHO + C2H5CO + OH;

R(butanal) ) 0.037

2601. pC4H9O ⇒ H + nC3H7CHO; R(butanal) ) 0.018


The formation of formaldehyde also mostly derives from the oxidationof n-heptane oxidation routes:

At higher temperature (820 K) where ca. 50% of the fuel is consumed,n-heptane and 1-butanol still mainly react with OH:

The C4H9OH radicals react with O2, forming a peroxy radicalthat in turn yields carbonyl compounds and OH (Figure 10).Therefore, the oxidation of butanol initiated via the low-temperatureoxidation of n-heptane also contributes to sustaining the radicalpool in this temperature regime. Butanal production via theoxidation of 1-butanol increases from what it was at 620 K, whereasthat through the decomposition of ketohydroperoxides (nC7KET24)strongly declines:

Ethylene production now involves beta-scission reactions of alkylradicals (reactions 137, 224, and 2161), not involved at 640 K:

Finally, formaldehyde’s formation mainly proceeds through thedecomposition of methoxy radicals and the oxidation of vinylradicals:

For the 50/50 1-butanol/heptane fuel mixture, in stoichio-metric conditions and low temperature (640 K), n-heptane stillmostly reacts with OH (Figure 10):

540. C2H4O2HS C2H4 + HO2; R(C2H4) ) 0.427

988. C2H5O2S C2H4 + HO2; R(C2H4) ) 0.202

2554. C2H5O2S C2H4 + HO2; R(C2H4) ) 0.2

35. CH3O(+M)S CH2O + H(+M); R(CH2O) ) 0.064

39. CH3O + O2S CH2O + HO2; R(CH2O) ) 0.158

77. CH2OH + O2S CH2O + HO2; R(CH2O) ) 0.073

504. O2C2H4OH S OH + 2CH2O; R(CH2O) ) 0.107

687. C4H8OH - 1O2S C2H5CHO + CH2O + OH;

R(CH2O) ) 0.062

787. pC4H9OS nC3H7 + CH2O; R(CH2O) ) 0.05

979. CH3COCH2OS CH3CO + CH2O; R(CH2O) ) 0.165

2563. CH2CHO + O2S CH2O + CO + OH;

R(CH2O) ) 0.127

2107. nC7H16 + OHS C7H15 - 1 + H2O;

R(nC7H16) ) -0.153

2108. nC7H16 + OHS C7H15 - 2 + H2O;

R(nC7H16))-0.272

2109. nC7H16 + OHS C7H15 - 3 + H2O;

R(nC7H16) ) -0.272

2110. nC7H16 + OHS C7H15 - 4 + H2O;

R(nC7H16) ) -0.136

2629. C4H9OH + OH ⇒ H2O + aC4H8OH;

R(butanol) ) -0.217

2630. C4H9OH + OH ⇒ H2O + pC4H9O;

R(butanol) ) -0.18

2631. C4H9OH + OH ⇒ H2O + dC4H8OH;

R(butanol) ) -0.17

2632. C4H9OH + OH ⇒ H2O + cC4H8OH;

R(butanol) ) -0.217

2633. C4H9OH + OH ⇒ H2O + C4H8OH - 1;

R(butanol) ) -0.217

Figure 10. Simplified reaction paths during the oxidation of a butanol/heptane 50/50 mol % fuel mixture in a JSR at 700 ms, 10 atm, � ) 1,and 640 K.

2274. C7H15O - 4S nC3H7CHO + nC3H7;

R(butanal) ) 0.024

2303. C7H14OOH4 - 2S OH + nC3H7CHO + C3H6;

R(butanal) ) 0.534


R(butanal) ) 0.23


2614. aC4H8OH + O2 ⇒ nC3H7CHO + HO2;

R(butanal) ) 0.023

137. nC3H7S CH3 + C2H4; R(C2H4) ) 0.157

224. pC4H9S C2H5 + C2H4; R(C2H4) ) 0.169

540. C2H4O2HS C2H4 + HO2; R(C2H4) ) 0.126

988. C2H5O2S C2H4 + HO2; R(C2H4) ) 0.093

2161. C7H15 - 1S C5H11 -1 + C2H4; R(C2H4) ) 0.073

2554. C2H5 + O2S C2H4 + HO2; R(C2H4) ) 0.3

35. CH3O(+M)SCH2O + H(+M); R(CH2O) ) 0.333

104. C2H3 + O2S CH2O + HCO; R(CH2O) ) 0.19

527. C3H5OS C2H3 + CH2O; R(CH2O) ) 0.08


R(CH2O) ) 0.06

2563. CH2CHO + O2 S CH2O + CO + OH;

R(CH2O) ) 0.07


1-Butanol also still reacts with OH by metathesis:

Butanal is mostly formed through the decomposition ofketohydroperoxides, whereas the route through 1-butanol oxida-tion to form butoxy radicals that in turn decompose into butanalis of minor importance even if it has increased significantly fromthe 20/80 1-butanol/heptane fuel mixture case:

As with the 20/80 fuel mixture, ethylene is mostly formed viathe oxidation of ethyl radicals:

Formaldehyde formation results partially from oxidations routesof 1-butanol through the intermediate formation of pC4H8O andC4H8OH-1:

Therefore, the importance of reactions 687 and 787 is muchhigher in the case of the oxidation of the 50/50 1-butanol/heptanefuel mixture.

At higher temperature (820 K), where ca. 50% of the fuel isconsumed, n-heptane and 1-butanol still react predominantlywith OH:

Again, butanal formation proceeds via:

Ethylene is mainly formed by through alkyl radicals decomposi-tion and ethyl oxidation:

2107. nC7H16 + OHS C7H15 -1 + H2O;

R(nC7H16) ) -0.16

2108. nC7H16 + OHS C7H15 - 2 + H2O;

R(nC7H16) ) -0.32

2109. nC7H16 + OHS C7H15 - 3 + H2O;

R(nC7H16) ) -0.32

2110. nC7H16 + OHS C7H15 - 4 + H2O;

R(nC7H16) ) -0.16

2629. C4H9OH + OH ⇒ H2O + aC4H8OH;

R(C4H9OH) ) -0.222

2630. C4H9OH + OH ⇒ H2O + pC4H9O;

R(C4H9OH) ) -0.223

2631. C4H9OH + OH ⇒ H2O + dC4H8OH;

R(C4H9OH) ) -0.089

2632. C4H9OH + OH ⇒ H2O + cC4H8OH;

R(C4H9OH) ) -0.222

2633. C4H9OH + OH ⇒ H2O + C4H8OH -1;

R(C4H9OH) ) -0.222


R(butanal) ) 0.849

2351. nC7KET34S nC3H7CHO + C2H5CO + OH;

R(butanal) ) 0.034


540. C2H4O2HS C2H4 + HO2; R(C2H4) ) 0.442

988. C2H5O2S C2H4 + HO2; R(C2H4) ) 0.212

2554. C2H5 + O2S C2H4 + HO2; R(C2H4) ) 0.21

39. CH3O + O2S CH2O + HO2; R(CH2O) ) 0.115

687. C4H9OS nC3H7 + CH2O; R(CH2O) ) 0.15


979. CH3COCH2OS CH3CO + CH2O; R(CH2O) ) 0.12


R(CH2O) ) 0.095

2107. nC7H16 + OHS C7H15 - 1 + H2O;

R(nC7H16) ) -0.152

2108. nC7H16 + OHS C7H15 - 2 + H2O;

R(nC7H16) ) -0.27

2109. nC7H16 + OHS C7H15 - 3 + H2O;

R(nC7H16) ) -0.27

629. C4H9 + OH + OH ⇒ H2O + aC4H8OH;

R(butanol) ) -0.216

2630. C4H9OH + OH ⇒ H2O + pC4H9O;

R(butanol) ) -0.18

2631. C4H9OH + OH ⇒ H2O + dC4H8OH;

R(butanol) ) -0.106

2632. C4H9OH + OH ⇒ H2O + cC4H8OH;

R(butanol) ) -0.216

2633. C4H9OH + OH ⇒ H2O + C4H8OH - 1;

R(butanol) ) -0.216

2303. C7H14OOH4 - 2S OH + nC3H7CHO + C3H6;

R(butanol) ) 0.326


R(butanol) ) 0.12

2601. pC4H9O ⇒ H + nC3H7CHO; R(butanol) ) 0.477

2614. aC4H8OH + O2 ⇒ nC3H7CHO + HO2;

R(butanal) ) 0.058

137. nC3H7S CH3 + C2H4; R(C2H4) ) 0.194


As before, formaldehyde is mainly produced by decompositionof methoxy radicals and by oxidation of vinyl radicals bymolecular oxygen:

5. Conclusion

The two main objectives of this study were achieved: (i)New data consisting of concentration profiles of reactants,

stable intermediates, and products were obtained as a functionof reaction temperature for the oxidation of 1-butanol-heptanemixtures in a JSR at 10 atm and 700 ms for fuel-lean andstoichiometric mixtures; (ii) A chemical kinetic modeling ofthese experiments was performed using two mechanismsderived from the literature. The more detailed mechanismpermitted a good representation of the present data. It wasused to delineate the main routes involved in the oxidationof the fuel mixtures. Two fuel compositions (1-butanol/heptane 20/80 and 50/50 in mol %) were used, showing verysimilar reaction paths. As expected, increasing the initialfraction of 1-butanol in the fuel increases the importance ofits reaction routes for the formation of the products measuredhere.

The semidetailed scheme gave a reasonable representationof the present data and could probably be useful for futureengine modeling where limiting the size of the chemicalmodel is still of paramount importance. Alternatively, betteraccuracy could be obtained using tabulated chemistry derivedfrom the detailed scheme.

Supporting Information Available: Reaction mechanisms andthe associated thermochemistry and a list of discarded species inthe reduced scheme. This information is available free of chargevia the Internet at http://pubs.acs.org/.

EF900261F

224. pC4H9S C2H5 + C2H4; R(C2H4) ) 0.145

540. C2H4O2HS C2H4 + HO2; R(C2H4) ) 0.128

988. C2H5O2S C2H4 + HO2; R(C2H4) ) 0.096

2161. C7H15 - 1S C5H11 - 1 + C2H4; R(C2H4) ) 0.06

2554. C2H5 + O2S C2H4 + HO2; R(C2H4) ) 0.306

35. CH3O(+M)S CH2O + H(+M); R(CH2O) ) 0.313

77. CH2OH + O2S CH2O + HO2; R(CH2O) ) 0.062

104. C2H3 + O2S CH2O + HCO; R(CH2O) ) 0.147

527. C2H5OS C2H3 + CH2O; R(CH2O) ) 0.063


R(CH2O) ) 0.087



R(CH2O) ) 0.066


experimental and modeling study of the kinetics of oxidation of butanol− n- ...

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