NASA Technical Memorandum 102443

Detailed Mechanism for

Oxidation of Benzene

David A. Bittker

Lewis Research Center

Cleveland, Ohio

May 1990

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DETAILED MECHANISM FOR OXIDATION OF BENZENE

David A. Bittker

National Aeronautics and Space Admlnlstratlon

Lewis Research Center

Cleveland Ohio 44135

ABSTRACT

A detailed mechanism for the oxidation of benzene is presented and used

to compute experimentally obtalned concentration profiles and Ignltlon delay

tlmes over a wide range of equivalence ratio and temperature. The computed

results agree qualitatively with all the experimental trends. Quantitatlve

agreement Is obtained with several of the composition profiles and for the

temperature dependence of the ign|tlon delay tlmes. There are Ind|catlons,

however, that some Important reactlons are as yet undiscovered in this

mechanism. Recent literature expressions have been used for the rate

coefficlents of most important reactions, except for some involving phenol.

The dlscrepancy between the phenol pyrolysis rate coefficlent used in this

work and a recent |Iterature expression remains to be explained.

INTRODUCTION

The major importance of aromatic hydrocarbons in practlcal engine fuels

has made It imperative to increase our understanding of the oxidation mechanism

of these compounds. Thls knowledge is necessary for controlling the combustlon

and emission characteristics of all gas turbine combustion systems. The

simplest aromatic, benzene, has been studied in several recent papers (Venkat

et al., 1982, McLaln et al., 1979, Kern et al., 1984, Hsu et al., 1984). A

review paper on aromatic hydrocarbon oxldatlon (Brezlnsky, 1986) qualitatively

outlined a benzene oxldatlon mechanism and presented a limited number of

experimentally measured profiles for one benzene-oxygen-nitrogen oxidation in
a high - temperature turbulent flow reactor. A more comprehensiveset of

concentratlon profiles for benzeneox1datlon In the samereactor was recently

reported by Lovell et al. (1988).

Ignition delay tlme measurements(Burcat et al., 1986) have been reported

for benzene-oxygen-argonmixtures ignited behind a reflected shock wave.

These delay times were measuredfrom pressure versus time profiles over a wide

range of starting conditions. The experiments in the last two mentioned

papers cover an equivalence ratio range from 0.5 to 2.0 and a temperature

range from about 1100 to 1600 K. Pressure varied from 1 to about 7 arm.

Thls paper presents a comprehensive benzeneoxidation mechanismwhich Is

used to compute the experimental results glven in the latter two papers. In

the following sections we present the results of using the newmechanismto

compute several concentration profiles for a range of equivalence ratio (¢)

from 0.74 to 1.3. Ignition delay times were also computedfor equivalence

ratlos of 0.5, l.O and 2.0. Weshowthat agreement between experimental and

computedtrends is generally good. A sensitivity analysis Is also presented to

demonstrate which reactions have the most significant effect on the computed

results. All kinetics and sensltlvlty computations were performed using the

NASAKinetics and Sensitivity Code, LSENS(Radhakrlshnan and Blttker, 1986,

1990). This code implements the decoupled direct method for sensitivity

analysis of nonlsothermal systems deve]oped by Radhakrlshnan (1987).

BENZENEOXIDATIONMECHANISM

The present mechanismis based on the qualitative schemeoutlined by

Brezlnsky (1986), which has been comblnedwlth new information presented in

several recent papers, as described below. It is also Important to use the

best possible set of hydrogen-oxygen reactlons, which are an Important part of

all hydrocarbon oxidation mechanisms. The hydrogen oxldatlon schemedeveloped
by Brabbs (1988) was used In these computations. Thls mechanism was obtained

by matching experimental ignition delay times in a shock tube under conditions

similar to those being used in the present study. A complete ]Istlng of the

reactlons and rate coefficients used Is given in table I.

One of the important reactions added to the mechanism of Brezinsky (1986)

Is

C6H 6 + C6H 5 = Cl2HlO + H (2)

It has recently been studied by Fahr and Steln (1988) and had a

significant Impact In obtaining agreement between computed and experimental

results. As an additional source of H atoms, thls reaction increased the

importance of the main hydrogen-oxygen branching reaction

H + 02 = OH + 0 (102)

Reaction (I02) was one of the important steps in the benzene oxidation for all

the experimental conditions studled In thls work. Other significant reactions

are the attack upon benzene by the radlcal pool of O, OH and H species and a]so

the reaction of pheny] radical (C6H 5) with molecular oxygen. These are:

C6H 6 + H = C6H 5 + H2 (4)

C6H 6 + 0 = C6H50 + H (5)

C6H 6 + OH _ C6H 5 + H20 (6)

C6H 5 + 02 = C6H50 + 0 (9)

As discussed by Brezlnsky (1986) and Nlcovlch et al. (1982), reaction (5) is

an addition process whose final products could be either those given or else

phenol. The displacement of a ring hydrogen by oxygen would seem to be a

slmpIer procedure than the rearrangement of the adduct to form phenol.

Therefore, the reaction has been wrltten as the chain-branchlng process.

Another important reaction Is the decomposition of phenoxy radical

C6H50 = C5H 5 + CO (8)
The reactions of the cyclopentadlenyl radical, C5H5, have been written to

conform to the new experimental results of Lovell et al. (1988). Their results

for benzene oxidation In the presence of NO2 Indicated that C5H5 reacts with

the radical pool (0 and OH) rather than wlth molecular oxygen. Therefore the

radlcal plus C5H5 reactions suggested by Brezlnsky (1986) have been used.

The formation and destruction reactions of phenol (C6H5OH)have been

studied In the recent work of He et a1. (1988) and Lovell et al. (1989). The

latter investigators studied the phenol pyrolysis in the sameflow reactor

used for the benzene oxidation studies described by Lovell et al. (1988). The

mechanismand rate coefficients they report were used as the starting point

for selectlng the reactions Involvlng phenol. This species is formed in the

benzeneoxidation by the reverse of reaction (12)

C6H50H_ C6H50+ H (12)

Reaction (12) exerts an Inhibiting effect on the oxidation and the high rate

coefficient given by Lovell et al. (1989) strongly supresses the entire

benzenereaction by competing for H atoms with the H + 02 chain branching

reaction. The pre-exponentlal factor for reaction (12) had to be reduced to

one-nlnth of Lovell's value. Other reactions of phenol with H and OHwere

taken from Lovell et al. (1989), along with the formation of cyclopentadlene

(C5H6) by the reaction of C5H5 with phenol. They are

C6HsOH+ H = C6H6 + OH (13)

C6H50H+ H = C6H50+ H2 (14)

C6H50H+ C5H5 = C6H50+ C5H6 (15)

C6H50H+ OH_ C6H50+ H20 (17)

Phenyl radical dissociates Into two llnear molecules according to the reaction

C6H 5 = C4H3 + C2H 2 (II)

A newly measured rate coefflclent (Braun-Unkhoff et al., 1988) for thls

pyrolysis was used here. Their expression is valid over a wide temperature

4
and pressure range including the condltlons for the data being modeled. The

measured reaction Is actually the Intramolecular rearrangement of phenyl to

form "llnear" C6H 5. This step is assumed to be followed by the very rapid

decomposition of that molecule to C4H 3 and C2H 2.

COMPARISON OF COMPUTED AND EXPERIMENTAL RESULTS

Concentratlon Profiles

Lovell et al. (1988) report composition versus time proflles for

benzene-oxygen-nltrogen oxidations at equivalence ratlos of 0.74, l.O and

1.3. The initial temperature in the flow reactor was 1096 K and remained

essentlally constant. The pressure was I arm. The exact zero of reaction

time is arbitrary, and was taken as the instant of Injection of the fuel into

the hot oxidant stream. In the computations the reactor was modeled as a

constant pressure (l atm) homogeneous batch reaction. For all computations in

this work the thermodynamic data are from the NASA Lewis Research Center data

base which is part of the NASA Chemical Equilibrium Composltlon Computer Code

of Gordon and McBride (1971). The data for phenyl and phenoxy radicals were

reported by Burcat, Zeleznlk and McBride (1985). New thermodynamic data for

several of the minor species were computed by Bonnle 3. McBride of NASA Lewis

Research Center. In particular we should mention that properties for ketyl

(C2HO) and ketene (C2H20) were recomputed using a newly computed heat of

formation for ketyl radical of 38.5 Kcal/mol. New thermodynamic propertles

were also computed for C5H 5, C5H50, and C5H40H by Dr. A. Burcat.

Comparlsons of computed with experlmental profiles are shown in Flgs. l

and 2. Figure I shows benzene and carbon monoxide profiles for the three

equivalence ratios used and Flg. 2 shows phenol and cyclopentadlene proflles.

Quantitative agreement between computed and experimental results is generally

better for benzene and carbon monoxide than for phenol and cyclopentadlene at

all three equivalence ratios. Figure l shows that good quantltatlve agreement

5
Is obtained for the benzene and carbon monoxlde profiles at ¢ = 0.74. The

computed overall rate of the reaction Is s11ghtly slower than the experimental

one, but the curves have close to the same slope for each species. For

¢ = l.O and 1.3 the computed benzene and CO curves show a somewhat faster

reaction rate than observed experlmentally. The percent difference between

computed and experimental slopes ranges from 27 to about 50 for these two

species. Thls change in the computed net rate from s11ghtly slower to faster

than the experimental va]ue as equlvalence ratio changes is an Indication of

an Incomplete mechanism. One or more unknown reactions may be unimportant for

lean mixtures but exert a significant effect on the reaction rate of richer

mixtures. Posslble examples of thls could be a reaction of benzene with the

hydroperoxyl radical or an alternate path for the reaction of benzene with

molecular oxygen. The phenol concentration proflles In Fig. 2 show that the

computed curves Increase faster than the experimental ones for all three

equivalence ratios. The best quantitative agreement is obtained for ¢ = 1.3,

and all computed curves follow the qualitative trends of the experimental

lines. The computed curves for cyclopentadlene show a slower rate of rise

than do the experimental 11nes. The final concentration reached by the

computed curves Is, however, s11ghtly higher than the value for the experimental

curves. In summary, the computed results match all the experimental results

qualltatlvely and there is some good quantitative matching for ¢ = 0.74.

Ignitlon Delay Times

The Ignition delay tlmes.of Burcat et al. (1986) were measured from

pressure versus tlme traces obtained by ignition behind a reflected shock wave.

The tlme Interval between shock passage and the first observed "signlflcant"

pressure rlse was taken as the Ignitlon delay time, _. The reflected shock

conditions reported by Burcat et a1. (1986) were flrst recomputed with
application of a small correctlon for attenuation of the Initial shock

veloclty. Only thlrty-five of the experlmental points reported In Burcat

et al. (1986) were used for our comparisons. A11 data for equlvalence ratio

of 0.25 were excluded, becauseexamination of the pressure traces showedthat

the pressure rlse was very poorly defined for these weak ignitions. In

addition, a11 Ignition delay times less than I00 psec were excluded because

pressure disturbances which cause nonuniform heating of the gas behind the

reflected shock contribute too hlgh a percentage error to these short ignition

delay times (Brabbs and Robertson, 1986). To match the experiment, the

computedignition delay tlme, _p, was obtained from each computedpressure

versus tlme plot. The computations were performed assuming a constant volume

batch reaction zone behind the shock wave. For each data point a computed

Ignition delay t|me was obtained from the computedpressure profile and was

defined as the reaction tlme for a 5 percent rlse in pressure. Thls method

gave temperature Increases between 30 and 50 K. It was considered to be a

satisfactory approximation to the experimental technique, which involved the

reading and Interpreting of photographic pressure traces.

Four mixture conditions amongthree equivalence ratlos were studled. The

experimental conditions for each mixture are given in Table II. Plots of

experlmental and computed Ignition delay time versus the reciprocal of

temperature for the four mixtures are shown in Figs. 3 to 6. The experimental

data polnts are shown for each mixture, as well as a least squares llne for

each set of computed and experlmental data. For a given mixture, each set of

data Is seen to obey an Arrhenlus type equatlon

or _p = A exp (AE/RT)

where R Is the unlversal gas constant and AE is an apparent actlvation

energy which measures the temperature dependence of the delay time for a fixed

set of Initlal concentrations. The agreement between experimental and computed

7
ignition delay times Is good for mixture 3 (¢ = 1.0, strong), falr for mixture

2 (¢ = 1.0, d11ute) and poor to falr for the other two mixtures. For ¢ = 0.5

and the dllute sto|chlometrlc mixture computed values are seen to be

consistently higher than the experlmental values, whereas the opposite

situation occurs wlth the ¢ = 2.0 mixture. It is significant to observe that,

for all mixtures, the computed Ignition delay times have values of AE quite

close to the experimental values. A summary of the differences between

computed and experlmental results |s given In Table III. Listed here are a11

the experimental and computed data points and the standard deviations for each

mixture. In the case of the strong stolchiometrIc mixture the standard

deviation of the computed results is well within the expected experimental

error. For the lean and the rich mixtures, standard deviations are about

45 percent, and the direction of the error Is opposite for the two mixtures,

as noted above.

In summary, the computatlons match closely the temperature dependence of

all the experimental results and quantitatlvely predict the delay times for

one stolchlometrIc mixture. The absolute agreement between computation and

experiment is fair to poor for the other mixtures. The most serious

deficiencies are in predicting delay times of the lean and rich mixtures. For

the lean mixture the predicted ignltlon tlmes are too slow, while for the rich

mixture they are too fast. Similar trends with equivalence ratio were

obtained for the concentration-profile computations, as mentioned above. These

results again suggest an unknown reaction.

Some new measurements of Ignltlon delay times in reflected-shock heated

benzene-oxygen-argon mixtures have recently been reported by ThyagaraJan and

Bhaskaran (1989). Their method of defining ignltlon delay time Is by detectlng

first 11ght emission, and may or may not be equivalent to the pressure-rlse

criterion of Burcat et a1. (1986). These new data agree with those of Burcat

8
for some condltlons but disagree by a factor of 2 to 3 at other conditions.

The temperature dependence of the new data Is much weaker than that of the

Burcat data. The new paper also presents a detailed reaction mechanism which

computes their experimental Ignltlon delay time results. However their

seventy-reactlon mechanlsm contains no steps Involvlng phenol or cyclopentadlene

and Is used by the authors to compute concentration versus time profiles only

for benzene and acetylene. The latter mechanlsm differs In several ways from

our mechanlsm. For example, two important reactlons are written with dlfferent

products. Those given for the benzene plus oxygen atom reaction are phenyl

and hydroxyl radlcal rather than phenoxy and H atom used here and recommended

by NIcovlch et a1. (1982). Also, the products of the phenyl plus molecular

oxygen reaction are C2H3, C2H2 and CO, rather than phenoxy and oxygen atom as

used here and recommended by other Investlgators (Brezlnsky, 1986; Lovell

et a1., 1988). Also no mention is made In thelr paper of different co111slonal

efflclencles for the colllslon partners In the H + 02 + M recombination

reaction. For a mechanlsm to be valld at temperatures around I000 K, these

collislonal efficiencles have to be considered.

In the present work we have used the correlatlon equation of Thyagarajan

and Bhaskaran to compute experimental Ignition delay times for several of

their mixtures and then used our mechanlsm to compute these same delay times.

Equlvalence ratio was varied from 0.5 to 2.0, pressure from 2 to I0 atm and

initial temperature from 1250 to 1750 K. In the worse cases our computed

results were about 50 percent lower than the experimental values. However, the

computed delay tlmes agreed within 15 percent or better with the experlmental

results for several cases. Therefore, even though we do not know the exact

method by which the delay times of Thyagarajan and Bhaskaran are defined, we
can say that our present comprehenslve mechanlsm glves computed ignltlon delay

tlmes qulte conslstent wlth the|r experlmental data.

DISCUSSION

The mechanlsm presented here successfully explains all the qualltatlve

trends and matches quantltatlvely several concentration proflles and Ignltlon

delay tlmes measured durlng the oxldatlon of benzene. During the development

of thls mechanlsm detalled sensitivlty analysls computations were performed to

determine the rate-controlllng reactlons and to monitor the effect of rate

coefflclent adjustments on the computed specles proflles. Figure 7 shows

normalized sens|tlvlty coefflclents for the reactlons whlch control benzene

concentration in the flow reactor experlments of Lovell et a1. (1988). The

magnltude of a coeff_clent Is the approximate percent change In the concentratlon

whlch would be caused by a 1 percent change in the rate coefflclent of the

glven reactlon. A negatlve sign Indlcates that the dlrection of the

concentratlon change Is opposlte to the dlrectlon of the rate coefflclent

change. Results are shown for the lean and rlch equlvalence ratlo, and a

reactlon tlme of 50 msec was chosen for thls and subsequent flgures. Three

reactlons, Independent of equlvalence ratio, are seen to be about equally

Important In controll_ng the consumptlon of the fuel; namely reactlons (8),

(12) and (102). The first and last of these reactlons promotes the oxidatlon,

but reactlon (12), whlch goes in reverse, Inhlblts the consumptlon of fuel.

The Informatlon in Fig. 7 shows the Importance of the competlng H + 02

processes (reactlons (102) and (114)), in controlllng the oxldatlon. Both

reactlons accelerate the oxldatlon process. In the hydrogen-oxygen system, the

H • 02 recomblnatlon Inhlblts the oxidatlon because of its chaln terminatlng

effect. In the benzene-oxygen system, however, hydroperoxyl radlcal acts as a

chaln carrier by react|ng wlth C6H5 radlcal to form hydroxyl radical (reactlon

I0
(lO)). Figure 7 shows that OH attack on benzene (reaction (6)) Is one of the

Important steps affecting Its rate of oxidation. Other reactions Involving

benzene, such as Its pyrolysis and reactions with phenyl and other radicals,

are also important In the mechanism. Since we are using a local sensltlvity

analysls method, we can only pinpolnt those reactions for which moderate rate

coeffIclent changes have an effect on the process. Many other reactions would

affect the oxidation rate of the fuel if their rate coefflclents were very

uncertaln and were changed by large factors.

Figures 8 to lO present sensltlvlty coefficients for carbon monoxide,

phenol and cyclopentadlene at the same conditions used in Fig. ?. Results are

similar for all species. The same three reactlons control all four

concentration profiles, and the accelerating effect of the H + 02 recombination

can be seen. Reactions (8) and (102) have been studied experimentally and

their rate coefficients have small uncertainties. We have only adjusted the

coefflcient of reactlon (8) by a factor of 1.2 to obtain better CO profiles.

The rate coefficient of reaction (12), the pyrolysis of phenol, is not as well

known. For this process we have used an activation energy equal to the

endothermiclty of the reaction, 88 Kcal/mol, which agrees with the value used

by Lovell et al. (1989). The preexponentlal factor was adjusted to give the

best possible flt to all the concentratlon profiles given by Lovell et al.

(1988). The value obtained, 3.0xlO 15, is about a factor of nine lower than

that used by Lovell et al. (19B9). This dlsagreement is another Indlcatlon

that the mechanism may be incomplete. It should be noted that the Lovell rate

coefficlent Is thermodynam|cally cons|stent with the expression given by He

et al. (1988) for the reverse of reaction (12). However, the lower A factor

used here for reaction (12) gives slmllar results when modeling both the flow

reactor and the shock ignition experiments. Some experlmental data are

overpredlcted and others are underpredlcted, depending on equivalence ratio.

II
Sensitivity analysis computations have also been performed to flnd out

which reactions were rate-controlllng on the Ignltlon process. Figures 11 to

13 show sensitivity coefflclents of pressure for three different starting

conditions. All three equivalence ratlos are shown and the temperatures used

range from 1209 to 1435 K. Under all three conditions, reactions (B), (12)

and (102) are the most Important ones which affect the ignition delay tlme as

measured by pressure rise. Reactions (8) and (I02) accelerate the Ignltlon

while reaction (12), which goes in reverse to form phenol, retards the Ignltlon.

These are the same reactions that were found to be most sensltlve In

determining the composition profiles for benzene oxidation at lower temperature

in a flow reactor. These computations show that the H + 02 recomblnatlon

reaction Is one of the rate controlling steps up to a temperature of 1363 K

but decreases In importance as the temperature is raised to 1435 K. As was

observed for the flow reactor oxldatlons, thls process accelerates the

Ignltlon of the fuel.

Thls sensitivity analysis shows that It would be difficult to make any

simple adjustments of rate coefficients In the hope of getting overall better

agreement wlth the experimental data. Any changes In rate coefficients would

Improve agreement at one equlvalence ratlo, but worsen agreement at a dlfferent

equivalence ratio. One has to search for addltional reactions which may resolve

the dlscrepancles. These can be reactions among the normal ground-state

species or possibly reactions among exclted-state species. Although the latter

are not usually considered Important at ordinary combustion temperatures, the

posslbIllty of exclted-state reactlon effects cannot be dlscounted. Reactions

Involving slnglet methylene radical have been suggested as playing a role in

hydrocarbon oxldatlon (Miller and Bowman, 1989). However, llttle accurate

12
Information is knownabout the thermodynamicsand chemical kinetics of excited

state species In the benzene-oxygensystem, as far as can be determined. So

the effect of any excited-state species reactions cannot be investigated at

this time. Wehave, however, madea series of computations with two reactions

not used previously. The first one added is the reaction of benzene wlth

hydroperoxyl radical

C6H6 + HO2 _ C6H5 + H202

AH= 25.6 Kcal/mol

The activation energy was taken as the heat of reaction and the preexponentlal

factor was varied from l.OxlO4 to l.OxlO 13 Computations showedthat thls

reaction had no effect on any varlable profile. In a separate set of

computations the reaction between benzeneand molecular oxygen was wrltten as

an addition and rearrangement process to give products phenoxy and hydroxyl

radlcals

C6H6 + 02 _ C6H50+ OH

AH= 2.3 Kcal/mol

Both the minimumactivation energy of 2.3 Kcal/mol and a higher value of

10 Kcal/mol were assumedand the preexponentlal factor was varied over a wide

range. This reaction had a strong accelerating effect on the oxidation. When

It was used wlth the Lovell mechanismfor phenol reactions, thls reaction

overcame the strong Inhlbltlng effect of the high phenol reactlon rate

coefficients. However, the oxldatlon process becametoo fast, and extremely

poor concentration profiles and Ignltlon delay tlmes were obtained. This

reaction was, therefore, abandoned.

CONCLUDINGREMARKS

A mechanismfor benzeneoxidation has been presented whlch explains

qualitatively all the observed trends of experimental concentration profiles

and ignition delay times over a range of equivalence ratio from 0.50 to 2.0.

13
The computations wlth this mechanism also quantltatlvely match much of these

data. However, It Is clear from our comparisons of computed and experlmental

results that thls mechanism still must be improved to obtain agreement between

computation and experiment and resolve questions about the rate coefficients

of reactions involvlng phenol. The need for additlonal reactions is indicated

by the fact that the computatlons underpredict the experimental results for

some equivalence ratios and overpredict them for other equivalence ratios.

ACKNOWLEDGEMENT

The author gratefully acknowledges the valuable asslstance of

Bonnie J. McBrlde, K. Radhakrishnan and A. Burcat durlng thls work.

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Perturbed by Nitrogen Dioxide Addition. In Twenty-Second Ssmposlum

(Internatlonal) on Combustion, The Combustion Institute, Pittsburgh, PA,

pp. 1063-1074.

Lovell, A.B., Brezinsky, K., and Glassman, I. <1989). The Gas Phase

Pyrolysls of Phenol. Int. J. Chem. Kinetics 21,547.

McLaln, A.G., Oachlmowskl., C.O., and Nllson, C.H. (1979). Chemical Klnetlc

Modeling of Benzene and Toluene Oxidatlon Behind Shock Waves. NASA TP-1472.

Mlller, O.A. and Bowman, C.T. (1989). Mechanism and Modellng of Nitrogen

Chemistry In Combustion. Prog. Energy Combust. Scl. 15, 287.

17
Mll]er, J.A., Mltchel], R.E., Smooke, M.D., and Kee, R.J. (1982). Toward a

Comprehensive Chemical Kinetic Mechanism For The Oxidation of Acetylene:

Comparison of Model Predictions w|th Results From Flame and Shock Tube

Experiments. In Nineteenth Symposlum (International) on Combustion, The

Combustion Institute, Pittsburgh, PA, pp. 181-196.

Nlcovlch, J.M., Gump, C.A. and Ravlshankara, A. R. (1982). Rates of Reactions

of O(3p) Hith Benzene and Toluene. J. Phys. Chem. 86, 1684.

Nlcovlch, J.M. and Ravlshankara, A.R. (1984). Reaction of Hydrogen Atom With

Benzene: Kinetics and Mechanism. J. Phys. Chem. 88, 2534.

Radhakrlshnan, K. (1987). Decoup]ed Direct Method For Sensitivity Analysis In

Combustion Kinetics. In Advances in Computer Methods For Partla] Dlfferentla]

Equatlons VI, R. VIchnevetsky and R.S. Stepleman, International Association

for Mathematics and Computers in Simulatlon, New Brunswick, NJ, pp. 479-486.

Radhakrlshnan, K. and Bittker, D.A. (1986). GCKP86 - An Efficient Code For

Genera] Chemical Kinetics and Sensitivity Analysis Computations. Proceedings

of Fall Meeting of Combustion Institute, Eastern Section, Pittsburgh, PA,

pp. 46-I.

Radhakrlshnan, K. and Bittker, D.A. (1990). LSENS - An Efflclent General

Chem|cal Kinetics and Sensitivity Analysls Code for Gas Phase Reactlons.

RP- , in preparatlon.

NASA

18
Slagle, I.R. and Gutman, D., (1986) Kinetics of the Reactlon of Propargyl

(C3H 3) With Molecular Oxygen From 293-900 K. In Twenty-First Symposium

(International) on Combustion, Combustlon Institute, Pittsburgh, PA,

pp. 875-883.

Thyagarajan, K. and Bhaskaran, K.A. (1989). High Temperature Gas Phase

Oxidation Kinetics of Benzene. In Seventeenth International Shock Tube

Symposium.

Venkat, C., Brezinsky, K. and Glassman, I. (1982). High Temperature Oxidation

of Aromatic Hydrocarbons. In Nineteenth Symposium (International) on

Combustion, The Combustlon Institute, Pittsburgh, PA, pp. 143-152.

19
Number

1

2

3

4

S

6

7

8

g

10

11

12

13

14

IS

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

Sl

52

53

54

55

56

57

58

Sg

TABLE I. - BENZENE OXIDATION MECHANISM

Reactlon

C6H 6 + 02 = C6H 5 + HO2

C6H 6 + C6H 5 _ C12H10 + H

C6H 6 _ C6H 5 + H

C6H 6 + H = C6H 5 + H2

C6H 6 + 0 = C6H50 + H

C6H6 , OH = C6H 5 + H20

C4H3 + M _ C4H2 + H + M

C6H50 = CsH S ÷ CO

C6H5 + 02 = C6H50 + 0

C6H S ÷ HO2 = C6H50 + OH

C6H 6 = C4H3 + C2H 2

C6H50H = C6H50 + H

C6HsOH + H = C6H 6 + OH

C6HsOH + H = C6H50 + H2

C6HsOH + CsH 5 = C6H50 + CsH 6

CsH 6 + 0 = CsH50 + H

C6HsOH + OH = C6H50 + H20

C5H50 = C4H 5 ÷ CO

CsH S * 0 = CsHsO

C5H 5 + OH = CsH40H , H

CsH40H _ C4H 4 + HCO

CsH 5 + HO2 = C5H50 + OH

2 C6H 5 = CI2HIo

C4H S = C2H 3 + C2H 2

C4H2 * 0 = C2HO + C2H

C4H2 + 0 = CO ÷ C3H 2

C4H 2 + OH = HCO + C3H 2

C2H 4 + M = C2H2 + H2

C2H 4 + OH _ C2H 3 + H20

C2H 4 + 0 = CH3 + HCO

C2H 4 + 0 = CH20 + CH2

C2H 4 ÷ OH = CH3 + CN20

C2H 3 + M = C2H2 + H + M

C2H 3 + 02 = CH20 + HCO

C2H3 + H _ C2H 2 + H2

C2H 3 + OH _ C2H 2 + H20

C2H 3 + CH2 = C2H 2 + CH3

C2H 3 ÷ C2H = 2 C2H2

C2H3 + 0 _ C2H20 + H

CH2 + CH2 = C2H 2 + H2

CH2 + CH2 = C2H 3 + H

CH2 + OH = CH + H20

CH2 • 0 = CH + OH

CH2 + 02 = CO2 + 2H

C2H 2 * M = C2H + H

C2H 2 + C2H 2 = C4H3 + H

C2H 2 + 0 = CH2 + CO

C2H 2 + 0 = C2HO + H

C2H 2 ÷ OH = C2H + H20

C2H 2 + OH = C2H20 + H

C2H 2 ÷ C2H = C4H 2 + H

C2H 2 + CH2 = C3H 3 + H

C3H4 ÷ M = C3H 3 + H + N

C2H20 ÷ OH = CH20 + HCO

C2H20 + OH = C2HO + H20

C2H20 + H = CH3 + CO

C2H20 + H = C2HO + H2

C2H20 + 0 = C2HO ÷ OH

C2H20 ÷ 0 = CH20 + CO

A, n Ea,

cm3, mol, sec cal/mol

6.30xi013 0.0 60 000.

4.0x1011 4 000.

5-0x1015 i lOB 000.

3.0xlO 12 B 100.

2.78xi013 4 910.

2.13xi013 4 580.

1.0 x1016 60 000

2.51xi0 II 43 900.

2.1xi012 7 470.

5.OxlO 13 1 000,

4.5xi013 72 530.

3.0xlO 15 88 000.

2.2xi013 7 910.

1.15x10TM 12 400.

4.0xlO 14 25 200.

l.Ox1011 0.0

3.0xlO 13 0.0

3.0xlO 16 15 000.

5.0xlO 13 0.0

1.OxlO13

1.0xlO 1S

2.0xlO 13

3.1xlO 12

1.4xi013

l.Ox1013

1.2xlO 12

3.0xi013

9.33xi016

4.79x1012

3.31xi012

2.51xi013

2.0xi012

7.94xi0 TM

3.98xi012

6.0xlO 12

S.OxlO 12

3.00xlO 13

3.00xlO 13

3.3x1013

4.0x1013

5.0x1012

2.51xi0 ]l

2.0xi011

1.5gxlO 12

4.17xi016

2.0×1012

1.6xi0 TM

4.0xlO 14

6.31xi012

3.2xi0 II

3.0xIO 13

1.2x1013

2.0xlO 17

2.BxlO 13

7.5xi012

1.13x1013

7.5x1013

5.0xlO 13

2.0x1013

0.67

0.68

0.0

32 900.

0.0

0.0

0.0

77 200.

I 230.

1 130.

5 000.

960.

31 500.

-250.

0.0

25 700_

25 000.

1 000.

107 000.

45 900.

g 890.

I0 660.

7 000

200.

0.0

6 600.

65 000.

0.0

3 000.

3 428.

8 000.

8 000.

0.0

Reference and adjustment

factor (A.F.)

McLaln et al. (1979)

Fahr and 5teln (1988)

H5U et al. (1984) (A.F. = 2.0) a

NlcovIch and Ravlshankara (1984)

NIcovlch et al. (1982)

Madronlch and Felder (1985)

Miller et al. (t982)

Lln and Ltn (1986)(A.F. = 1.2)

Lln and Lln (1987)

Estimated

Braun-Unkhoff et al. (1988)

Th_s work

Love11 et aI. (1989)

Love11 et al. (1989)

Thls work

Estlmated

Thls work

Estlmated

Colket (1986)

Estimated

McLaln (1979)

Miller et at. (1982)

Miller et at. (1982)

Mlller et al. (1982)

Nestbrook and Dryer (1984)

1

Westbrook and Dryer (1984)(A.F. - 0.38)

Slagle and Gutman (1986)

Miller et al. (1982)

Westbrook and Dryer (Ig84)

Mlller et al. (1982)

1

Frank et al. (1986)

Frank et al. (1986)

Nestbrook and Dryer (1984)

Nestbrook and Dryer (1984)

Miller eta]. (1982)

Boh]and et al. (1986)

Pamldlmukkala et a1. (IgB7)

Mil}er et al. (1982)

Mlller et al. (1982)

Hestbrook and Dryer (1984)

Miller et a1. (1982)

20
Number

TABLE I

Reaction A,

cm3, mol, sec

60 C2H20 + M = CH2 + CO + M

61 C2HO + 02 = 2 CO + OH

62 C2HO + 0 = 2 CO + H

63 C2NO + OH = 2 HCO

64 C2HO + H = CH2 + CO

65 C2HO + CH2 = C2H 3 + CO

66 C2HO + CH2 = CH20 + C2H

67 C2HO + C2HO = C2H 2 + 2 CO

68 C2H + OH = C2HO + H

69 C2H + 02 = C2HO + 0

70 C2H + 0 = CO + CH

71 CH4 + M = CH3 + H + M

72 CH4 + 02 = CH3 + HO2

73 CH4 + H = CH3 + H2

74 CH4 ÷ OH = CH3 + H20

75 CH4 * 0 : CH3 + OH

76 CH 3 + 02 = CH30 + 0

77 CH 3 + OH : CH30 + H

78 CH30 + M = CH20 ÷ H

79 CH30 + 02 : CH20 + HO2

80 CH30 + H = CH20 + H2

81 CH3 + CH3 : C2H 4 ÷ H2

82 CH3 + 0 = CH20 + H

83 CH3 + CH2(] = CH4 + HCO

84 CH3 + HCO = CH4 + CO

85 CH3 + HO2 = CH30 + OH

86 CH20 + M = HCO + H + M

87 CH20 + OH = HCO + H20

88 CH20 + H = HCO + H2

89 CH20 + 0 = HCO + OH

90 HCO + HO2 _ CH20 + 02

91 HCO + M = H + CO ÷ M

92 HCO + 02 _ CO + HO2

93 HCO + OH : CO + H20

94 HCO + H = CO + H2

95 HCO + 0 = CO + OH

96 CH + 02 : HCO + 0

97 CO * 0 + M = CO2 + M

98 CO + 02 = CO2 + 0

99 CO + OH = CO2 + H

lO0 CO * HO2 # CO2 + OH

lOl 0 + H20 = OH + OH

102 H + 02 -_ OH + 0

I03 0 + H2 = OH + H

104 H + HO2 = H2 + 02

105 0 + HO2 = OH + 02

106 HO2 + OH = H20 + 02

I07 H + HO2 = OH + OH

108 H2 ÷ HO2 = H202 ÷ H

Tog OH + H202 = H20 + HO2

llO HO2 + HO2 = H202 ÷ 02

Ill H + H202 = OH + H20

I12 H202 + M _ OH + OH + M

ll3 H2 + OH = H20 + H

ll4 H + 02 + M _ HO2 + M

If5 H20 ÷ M = H + OH + M

I16 H + 0 ÷ M = OH + M

117 H2 ÷ M = H + H + M

118 02 * M =0 * 0 + M

- Concluded.

n Ea,

cal/mol

2.0xIO 16 60 000.

1.46xi012 2 500.

1.20xlO 12 0.0

l'OxlOl3 1

5.0xlO 13

3.0xlO 13

l.OxIO 13 2 000.

l.OxlO 13 0.0

2.0xlO 13 0.0

5.0xlO 13 l 500.

5,0xlO 13 0.0

2.0xlO 17 88 000.

7.94xi013 56 000.

1.26xlOTM II 900.

2.5OxlO 13 5 OlD.

1.90xlO14 II 720.

4.79xi013 29 000.

6,30x1012 0.0

5.0xlO 13 21 000.

l.OxlO 12 6 000.

2.0x1013 0.0

l.OxlO 16 32 000.

1.29x10 TM 2 000.

l.OxlO lO 0'.'5 6 000.

3,0xlO II 0.5 0.0

2.00xlO 13 O.O 0.0

5.0xIO 16 76 500.

3,0xlO 13 1 200.

2.5xl0 ]3 3 990.

3,5xi013 3 510.

l,OxlO TM 3 000.

2.94x10 TM 15 570.

3.31xl012 7 000.

1,OxlO TM 0.0

2'0xi014 I

l.OxlO 14

l.OxlO 13

5,9xl015 4 I00.

2.5xl012 47 690.

4.17x1011 1 000.

5.75x1013 22 930.

6.8xi013 18 365,

1,89xi014 16 400.

4,20xt014 13 750.

7.28xi013 2 126.

5.0xlO 13 1 000.

8.0xIO 12 0.0

1.34xi0 TM : 1 070.

7.91xi013 j 25 000.

6.1xlO ]2 I 430.

1.8xlO 12 0.0

7.8x101_ 0.0

1.44xi01 45 5TO,

4.74xi013 6 098.

1.46xi015 -l 000.

1.30xlO 15 I05 140.

7.1xlO 18 -l'.O 0.0

2.2xi014 0.0 96 000.

1.8xlO 18 -l.O 118 000.

Reference and adjustment

factor (A.F.)

t

Nestbrook and Dryer (1984)

M111er et al. (1982)

!

Nestbrook and Dryer (1984)

Westbrook and Dryer (1984)

Brabbs and Brokaw (1974)

Brabbs and BroKaw (1974)

Brabbs and Brokaw (1974)

HestbrooK and Dryer (1984)

Westley (1980)

Westbrook and Dryer (1984)

I

I

Warn'atz (1984)

1

Hestley (1980)

Cherlan et al., (1981) b

WestbrcK_k and Dryer (1984)

Brabbs and Brokaw (1974)

Westbrook and Dryer (1984)

Brabbs and MuslaK (1988)

aAdJustment for Increased pressure (approximate) from K1efer et al. (1985) used for Ignltion-delay computatlons.

bcomputed from reverse reaction rate coefflclent and equlllbrlum constant.

COLLISIONAL EFFICIENCIES

Reactlon 112:

Reactlon 114:

Reactlon 115:

Reaction 117:

H2 = 2.3; 02 = 0.78; H20 = 6.0; H202 - 6.6

H2 = 3.0; 02 = 1.3; H20 - 21.3; N2 = 1.3; CO2 = 7.0; C6H 6 = 20.0; CH4 = 5.0

H2 = 4.0; 02 = 1.5; H20 = 20.0; N2 = 1.5; CO2 = 4.0; C6H 6 = 20.0

H2 . 4.1; 02 = 2.0; H20 = 15.0; N2 = 2.0

[Rate constant used equals tabulated expresslon multlplled by adjustment Factor.]

21
TABLE II. - INITIAL MIXTURE CONDITIONS FOR IGNITION DELAY TIME MEASUREMENTS

Mixture Equivalence

ratio,

0.5

1.0

1.0

2.0

Benzene,

mol %

1.354

.516

1.690

1.354

Oxygen,

mol %

20.313

3.868

12.675

5.093

Argon,

mol %

78.333

95.616

85.635

93.553

Initial

temperature

range,

K

1209-1345

1345-1528

1283-1435

1363-1600

Initial

pressure,

arm

1.9-2.2

5.6-7.1

2.0-2.5

2.0-2.6

TABLE III - COMPARISON OF COMPUTED AND EXPERIMENTAL INGINTION DELAY TIMES

Mixture number

and descriptlon

1. Equivalence

ratio : 0.5

p _ 2 ATM.

2. Equlvalence

ratio : 1.0

(dllute)

p = 5-7 ATM.

3. Equivalence

ratio : 1.0

(strong)

p _=2 ATM.

4. Equivalence

ratio = 2.0

p a 2 ATM.

Inltlal

temperature,

K

1209.

1227.

1254.

1276.

1291.

1307.

1314.

1345.

1345.

1374.

1402.

1412.

1428.

1482.

1525.

1528.

1283.

1290.

1294.

1328.

1355.

1369.

1379.

1405.

1408.

1417.

1435.

1363.

1415.

1457.

1540.

1554,

1570.

1582.

1600.

Experlmental

ignltlon

delay time,

psec

878.

743.

435.

330.

272.

185.

202.

159.

755.

604.

415.

412,

367.

213.

122.

122.

750.

613.

607.

490.

303.

287.

291.

198.

189.

178.

151.

1520.

890.

599.

274.

243.

211 .

157.

154.

Computed Ignttion

delay time,

psec

1200,

960.

600.

480.

390,

315.

300.

209.

640.

445.

332.

295.

250.

147.

I00.

99.

760.

700.

660.

440.

320.

280.

258.

208.

178.

163.

130.

780.

440.

320.

150.

130.

II0.

I00.

90.

Percent

difference

36.7

29.2

37.9

45.4

43.4

70.3

48.5

31.4

-]5.2

-26.3

-20.0

-28.4

-31.9

-31.0

-18.0

-18,9

1.3

14.2

8.7

-I0.2

5.6

-2.4

-II.3

5.1

-5.8

-8.4

-13.9

-48.7

-50.6

-46.6

-45.3

-46.5

-47.9

-36.3

-41.5

Percent

standard

devlation

44.5

24.5

8.9

45.6

22
1800

1600

1400

o.

1200

Z

o_ lOOO I-,

_ 8oo

Z

_ r_o

§ 4oo

20O

-\ i

(a) _ = 0.74.

1400 _-_

. 1200 -

O 1000 "-

I.-

_ _o

FZ

_ 6oo

0 40O

2OO

(b)_= _.o.

1800

_" 1600

1400

O

>

v 1200

13.

o.. 1000

Z

_O 800

_ 6oo

Z

O 400

0 21)0

_C6H6

//_/2

20 40 60 80 100 120 140 160 180

TIME, msec

(c)q) = 1.3.

Figure I, - Benzene and CO concentration

versus time, To = 1096 K,

240 -

,-, 200

120

817 i,°

EXPERIMENTAL

COMPUTED

/ C6H5OH /

/'_ c5.6

_"r'_'_.,.-a ,_"r" i i I I I I

(a) q>= 0.74.

200

Q.

o,. 160

-_ 120

_. 80

z

w

0 40

z

0

0 0

I

L /Y _c6;%......-

(b)_ = 1.0.

_3; 120 H5OH

t_" 40 _-f_C5H6

_O _ 1"f_-'_'_"_--'l" "1 - I I I I I

0 20 40 60 80 100 120 140 160 180

TIME, msec

(c) ¢p= 1,3.

Figure 2. - Cyclopentadiene and phenol

concentration versus time. T o = 1096 K.

1000

::L

800

C-- 600

400

200

2000 --

EXPERIMENT

COMPUTE D

/

,'2'

-Z

lOO I I I

7.2 7.4 7,6 7.8 8.0 8.2 8.4

10 O00/T, K -1

I I I

1350 1280 1219

TEMPERATURE, K

Figure 3. - Benzene-oxygen-argon ignition

delay time versus reciprocal of

temperature, q_: 0.5.

23
IOO0

8O0

=L

u_

4oo

I-

>-

,_ 3oo

LU

(3

Z

100

8O

- xpE.,MENT ..

.,=]/

-"1 I I I I 1

6.4 6.6 6,8 7.0 7.2 7,4 7.6

10 O00/T. K -1

I 1 I

1515 1430 1350

TEMPERATURE, K

Figure 4. - Benzene-oxygen-argon ignition

delay time versus reciprocal of temperature, (p = 1,0, dilute mixture 95.6% At,

1000

moo

_- 4O0

_ 2oo

100

_-- _ EXPERIMENT /j

I I I I I

6.8 7.0 7.2 7.4 7.6 7.8 8.0

10 ooo/'r, K-1

I I I

1430 13.50 1280

TEMPERATURE, K

Figure 5. - Benzene-oxygen-argon ignition

delay time versus reciprocal of temperature, _ = 1.0, strong mixture 85.6% At.

2000 --

1000

8O0

_=

I- 400

>-

5

w

a

__ 200

Z

100

EXPERIMENT /

__ ------ COMPUTEu --_. Jf

J

Z-"

_ //

/

so- I I I I I I

6.2 6.4 6.6 6.8 7.0 7.2 7.4

10 000/T, K -1

1 I I I

1615 1515 1430 1350

TEMPERATURE, K

Figure 6. - Benzene-oxygen-argon ignition

delay time versus reciprocal of

temperature,cp = 2.0.

24
NO,

12

8

102

17

114

6

20

REACTION

C6H5OH _C6H50 + H

C6H50_ CsH 5 + CO

H+O2_OH+O

SENSITIVITY COEFFICIENT

-.4 -.3 -.2 -.1 0 .1 .2 .3 4

I I I I I I I I

Z22222Z22 

C,6HsOH + OH _ C6H50 + H20

H+O2+M _-HO2+M E_

C6H6+ OH _ C6H5 + H20 L_

CsH 5 + OH _ CsH4OH + H I_

(a) Equivalence ratio 0.74, temperatu re 1096 K, time = 50 msec.

SENSITIVITY COEFFICIENT

NO.

12

8

102

17

114

6

2O

REACTION

-.16 -+12 -.08 -.04

I I I t

C6HsOH _ C6H50 + H

C6H50_ C5H 5 + CO

H+O2_OH+O

C6HsOH + OH _ C6H50 + H20

H+O2+ M _- HO2+ M

C6H6+ OH _-- C6H5 * 1"120

C5H5+ OH _ C5H4OH + H I_

0 .04 .08 .12 16

I I I I 1

(b) Equivalence ratio 1.3, temperature 1096 K, time = 50 msec.

Figure 7. - Sensitivity coefficients for benzene concentration

25
No.

12

102

114

REACTION

SENSITIVITY COEFFICIENT

-1.4 -1.2 -1.0 --.0.8 -0.6 -0.4 -0.2

I I I I I I I .

C6H50 _ C5H 5 + CO

C6H5OH _ C6H50 + H

H+O2_OH + O

H÷O2+M _HO2+M

C6H 6 + O _ C6H50 * H

17 C6HsOH + OH _C6H50 + H_)

19 C5H5+ O _ C5H50

0 .2 .4 .6 .8 1.0 1.2 1.4

I I I I [ I I

ZZZ22222222 

;E3

(a) Equivalence ratio 0.74, temperature 1096 K, time = 50 msec.

No.

12

102

114

REACTION

SENSITIVITY COEFFICIENT

I I I I I I .

-1.4-1.2-1.0-0.8-0.6-0.4 -0.2 0 .2 .4 ,6 .8 1.0 1.2 1.4

I I I

C6H50 _ CsH 5 + CO

C6H5OH _ C6H50 + H

H + O2_OH + O

H+O2+M _HO2+M

C6H 6 + O _ C6H50 + H L_

17 C6HsOH, OH _- C6H50, H2O

I I I I I

19 C5H5 + O _ C5H50 33

(b) Equivalence ratio 1.3, temperature 1096 K, time = 50 msec.

Figure 8. - Sensitivity coefficients for carbon monoxide concentration.

26
NO.

17

12

8

102

6

2O

114

REACTION

SENSITIVITY COEFFICIENT

-.8 -.6 -.4 -.2 0

I I I I I

E2222222 

.2 .4 .6 .8

I I I I

C6HsOH + OH _ C6H50 * H20

C6HsOH _- C6H50 + H

C6H50 _--- CsH 5 + CO

H+O2_OH+O

c6HB.OH_ %HS +H20

CsH 5 + OH _ CsH4OH + H

H+O2+M _ HO2+ M

(a) Equivalence ratio 0,74, temperature 1096 K, time = 50 msec,

SENSITIVITY COEFFICIENT

NO'I

102

12

8

17!

114

20

6

REACTION

-.8

I

H+O2_OH+O

CoHsOH_- CoHsO÷H

CBHsO_ CsH5+co

C6NsOH + OH _ C6H50 + H20

H+O2+M _HO2+M

C5H 5 + OH _- CsH4OH + H

C,6H 6 + OH _ C6H 5 + H20

-.6 -,4 -.2 0 .2 .4 ,6

I I I I 1 I

Z2 Z;EE;EEE 

E;:EEEEE;EEE 

EE3

(b) Equivalence ratio 1.3, temperature 1096 K, tJme = 50 msec.

Figure 9. - Sensitivity coefficients for phenol concentration.

27
No. REACTION

1021 H+O2_OH+O

e %HsO_ %%. CO

12 CeHsOH = C6H50, H

SENSITIVITY COEFFICIENT

-1.2 -1.0 -.8 -.6 -.4 -.2 0 .2 .4 .6 .8 1.0 1.2

I I I I I I I I I I I I I

I/////////,/,//,/J

15 C6HsOH + C5H 5 _C6H50 + CsH 6

17

19

C_HsC_-I ÷ OH = C6H50 + H20 [_

C6H 6 * OH = C6H S + H20

CsNs÷o _ %HsO

(a) Equivalence ratio 0.74, temperature 1096 K, time = 50 reset.

SENSITIVITY COEFFICIENT

No.

_102

8

12

15

17

6

9

REACTION

-1.6 -1.2 -.8 -.4

I [ I I

H+O2_OH+O

%HsO = %H s÷co

C6HsOH _ C6H50 + H

ICeHsOH + C5H 5 _ C6H50 + CsH 6

CBH5OH + OH ¢ C6HsO + H20 [_

C6H 6 + OH _-_ C6H 5 + H20

CBH 5 + 02 _-_ C6H50 + O _'_

0 .4 .8 1.2 1.6

I I L I t

(b) Equivalence ratio 1.3, temperature 1096 K, time = 50 msec

Figure 10. - Sensi_tty coefficients for cyc_opentadiene concentration.

28
No.

12

8

102

114

9O

17

REACTION

SENSITIVITY COEFFICIENT

-.04 -.03 -.02 -.01 0 .01 .02 .03 .04

I I I I I I I 1

C6HsOH _- C6H50 + H Z22222Z 

C6H50 _ C5H 5 + CO

H+O2_OH+O

H+O2+M _HO2+M

HCO + HO 2 _ CH20 + 02

C6H5OH + OH _-_ C6H50 + H20 [_

C6H 6 + 0 _ C15H50 + H [_

Figure 11. - Sensitivity coefficients for pressure; equivalence ratio 0.5, temperature 1209 K, time = 900 FLsec.

No.

102

12

8

19

9

17

REACTION

H+O2_OH+O

C6H5OH _ C6H50 + H

C6H50 _ C5H 5 + CO

C5H 5 + 0 _ C5H50

C6H 5 + 02 _- C6H50 + O

-.04

I

SENSITIVITY COEFFICIENT

-.03 -.02 -.01 0 .01 .02 .03

I I I I I I I

;E ;EEZE 

C6HsOH + OH _ C6H50 + H20

C6H 6 + O _ C6H50 + H I_

Figure 12. - Sensitivity coefficients for pressure; equivalence ratio 1.0 (85% Ar), temperature 1435 K,

time = 100 iJ.sec.

.04

I

29
NO.

102

12

REACTION

H+O2_OH+O

C6H5OH _ C6H50 + H

C6H50 _ CsH 5 + CO

5 C6H 6 + O _ C6H50 + H

19 C5H 5 + O ¢ C,5H50

114 H + O2+ M_ HO2 + M

17 C6H5OH + OH _ C6H50 + H20

SENSITIVITY COEFFICIENT

-.04 -.03 -.02 --.01

I I I I

0 .01 .02 .03 .04

l I I I I

Figure 13. - SenslUvlty coefficients for pressure; equivalence ratio 2.0, temperature 1363 K, time = 600 iJ.sec.

3O
Report Documentation Page NaltonalAeronautics and

SpaceAdrninislration

1. Report No. 2. Government Accession No. 3, Recipient's Catalog No.

NASA TM- 102443

4. Title and Subtitle

Detailed Mechanism for Oxidation of Benzine

7. Author(s)

David A. Bittker

9. Performing Organization Name and Address

National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135-3191

12. Sponsoring Agency Name and Address

National Aeronautics and Space Administration

Washington, D.C. 20546-0001

5. Report Dale

May 1990

6. Performing Organization Code

8. Performing Organization Report No.

E-5224

10. Work Unit No.

505-62-21

11. Contract or Grant No.

13. Type of Report and Period Covered

Technical Memorandum

14. Sponsoring Agency Code

15. Supplementary Notes

16. Abstract

A detailed mechanism for the oxidation of benzene is presented and used to compute experimentally obtained

concentration profiles and ignition delay times over a wide range of equivalence ratio and temperature. The

computed results agree qualitatively with all the experimental trends. Quantitative agreement is obtained with

several of the composition profiles and for the temperature dependence of the ignition delay times. There arc

indications, however, that some important reactions are as yet undiscovered in this mechanism. Recent literature

expressions have been used for the rate coefficients of most important reactions, except for some involving

phenol. The discrepancy between the phenol pyrolysis rate coefficient used in this work and a recent literature

expression remains to be explained.

17. Key Words (Suggested by Author(s))

Benzene oxidation

Kinetic mechanisms

Aromatic fuel oxidation

18. Distribution Statement

Unclassified- Unlimited

Subject Category 25

19. Security Classif. (of this report) T 20. Security Classif. (of this page)

Unclassified Unclassified

/

21. No. of pages

32

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