, 

NASA /CR-2003-212293 

5ulfur L Oxidation and Contrail 

Yrecursor Chemistry 

Kenneth J. De Witt 

University of Toledo, Toledo, Ohio 

April 2003 

https://ntrs.nasa.gov/search.jsp?R=20030055681 2018-05-15T16:39:18+00:00Z
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NASA /CR-2003-212293 

Slulfur Oxidation and 

F’recursor Chemistry 

Kenneth J. De Witt 

University of Toledo, Toledo, Ohio 

Prepared under Grant NAGS2674 

National Aeronautics and 

Space Administration 

Glenn Research Center 

Contrail 

April 2003 
Acknowledgments 

We wish to thank Dr. Martin J. Rabinowitz, NASA Glenn Research Center, the grant monitor, for his invaluable 

advice and support throughout this study. This study was supported by the NASA Glenn Research Center under 

the grant NRA-01-GRC-02 and NAG3-2674. All experiments and computations in this study were performed 

at the NASA Glenn Research Center in Cleveland, Ohio. Additional valuable support was provided 

by Dr. Soon Muk Hwang, Department of Chemical Engineering, University of Toledo. 

, 

This report contains preliminary 

findings, subject to revision as 

analysis proceeds. 

The Propulsion and Power Program at 

NASA Glenn Research Center sponsored this work. 

Available from 

NASA Center for Aerospace Information 

7121 Standard Drive 

Hanover, MD 21076 

National Technical Information Service 

5285 Port Royal Road * 

Springfield, VA 22100 

Available electronically at htb:/ /eltrs.erc.nasa.eov 
Sulfur Oxidation and Contrail Precursor Chemistry 

Kenneth J. De Witt, Principal Investigator 

Department of Chemical Engineering 

The University of Toledo 

Toledo, Ohio 43606 

Abstract 

Sulfuric acid (I :so4), formed in commercial aircraft operations via fuel-S + SO2 + so3 + 

H2S04, plays an important role in the formation of contrails. It is believed that the first step 

occurs inside the combustor, the second step in the engine exit nozzle, and the third step in the 

exhaust plume. Thus, measurements of the sulfur oxidation rates are critical to the understanding 

of contrail formation. Field measurements of contrails formed behind commercial aircraft 

indicate that significantly greater conversion of fuel-bound sulfur to sulfate aerosol occurs than 

can be explained by our current knowledge of contrail physics and chemistry. The conversion of 

sulfur from S(1V) to S(V1) oxidation state, required for sulfate aerosol formation, is 

thermodynamically favored for the conditions that exist within jet engines but is kinetically 

disfavored. The principal reaction pathway is O+S02+M + S03+M. The rates of this reaction 

have never been measured in the temperature and pressure regimes available to aircraft 

operation. 

In the first year (FY02) of this project, we performed a series of experiments to elucidate the rate 

in:formation for the O+S02+M + SO3+M reaction. The work performed is described below, 

following the proposed work plan. Because we used the H2/02 system for an 0-atom source and 

rate coefficients were obtained via computer simulation, construction of a reaction mechanism 

and either recalculation or estimation of thermodynamic properties of H,SO, species are 

described first. 

Reaction Mechanism of the S02/H2/02 System 

For the H2/02 system, we adopted a reaction mechanism of 20 elementary reactions that has been 

tested extensively at various conditions. 1-3 Then, additional reactions for SO2 oxidation by H,O, 

species in the S02/H2/02 system and their rate coefficients were critically reviewed and a 

reaction mechanism of 19 reactions for this system was composed. A comprehensive but 

tnrncated reaction mechanism for the SOl/H2/02 system is given in Table I of Appendix A. A 

brief review of important rate coefficients is given in the Discussion section. 

Thermodynamic data of relevant species of H2/02/S02 System 

In computer modeling using a reaction mechanism for practical combustion systems or for 

extracting rate coefficient information, reliable thermodynamic properties ( A fg(298.15 K), 

H(/T), SP), GP), C,O) of the reacting species are necessary. Recently the value of D0298.15(H013)=118.81 f 0.07 kcal mol-' was measured by Ruscic et From this new bond dissociation 

NASAICR-2003-2 12293 1 
I enthalpy of H20, A fp(298.15 K) of OH=8.9 1 f 0.07 kcal mol-' has been reestablished and the 

differences from the widely used value of Gurvich et ai? or JANAF6 have been discussed in 

great detail4 Previously we had used 9.4 1 k 0.05 kcal mol-' for A fp(298.15 K) of OH, based 

upon the recommendation of Gurvich et al. The difference of 0.49 kcal mol-' from the new value 

of Ruscic et al. is quite large. Considering the uncertainty in obtaining Do(O-H) by Gurvich et al. 

from spectroscopic measurements and an unambiguous direct measurement of Do(H-OH) by a 

photoionization experiment by Ruscic et al., we adopted the new A fp(298.15 K) of 

OH=8.91 k 0.07 kcal mol-' of Ruscic et al. and readjusted all thermodynamic properties of OH 

accordingly. The thermodynamic properties of other species in the H2/02 system are unchanged. 

I While thermodynamic properties of species in the H2/02 system are more or less well 

established, those of H,SO, species (HS, HSO, HOSO, HS02, and HOS02) are virtually 

unknown. Using available experimental data and theoretical calculations, thermodynamic data of 

these species are estimated. Details are described in Appendix B. 

Selection of Experimental Conditions via Sensitivity Analysis 

In determining rate coefficients of the reaction 

an 0-atom source must be found. In this work 0-atoms were produced from H2/02 reactions. Le., 

consume and produce 0-atoms in the H2/02 system are, respectively 

I the H2/02 reaction system was perturbed with a small amount of S02. The major reactions that 

and 

OtH2 + OH+H 

H+02 -+ OH+O 

Hence, in the S02/H2/02 system, R21 would compete with R2. If we use rich H2/02 mixtures, 0- 

atoms would be consumed mainly by R2. This restricts us to consider lean H2/02 mixtures only. 

Figure 1 shows R=llog( [iIpk/[H2]~)I as a function of equivalence ratio $ of H2/02 mixtures, where 

i=O, OH, and H. Small R values indicate production of a large amount of species i. Obviously, 

lean mixtures are more suitable than rich mixtures in this regard. However, at given jet engine 

exhaust nozzle temperatures (900 to 1200 K), the following reaction will compete with Rl for Hatoms 

Thus, it is also desirable to select reaction mixtures that produce a less amount of H-atoms. 

Sensitivity analyses for an elapsed time to reach half of the absorption maximum ( z 50) were 

performed using the following baseline H2/02 mixture (without S02) with various levels of 

sensitization by SO2 at T=1000 K, p=15.0 pmol ~m-~; 0.5% H2/10.0% 02 ($=0.025), 0.15%- 

3.0% S02/ 0.5% H2/10.0% 02 ($=0.025)/Ar. In the baseline mixture, R9, R1, R2, and R3 show 

sensitivities for 750 in that order. Figure 2(a) shows a sensitivity spectra for 0.5% H2/10.0% 

I NASAJCR-2003-2 12293 2 
0;:/89.5% Ar mixture. Adding 0.15%, 0.25%, and 0.5% SO2 to a 0.5% Hz/lO.O% Oz/Ar mixture 

prloduced only a trace level of sensitivity for R2 1. The sensitivity of R2 1 was found to be 

dependent upon the S02/H2 ratio in the mixture. Furthermore, as the S02/H2 ratio is increased, 

the sensitivity of R2 1 and R9 is notably increased together with the relative importance of R2 1 

over R9. Figure 2(b) shows a sensitivity spectra for the 2.0% SO21 0.5% H2/10.0% 02/88.5% Ar 

mixture. Based upon this sensitivity analyses we selected the following three mixtures: for the 

baseline experiments, 0.5% Hz/lO.O% 02/89.5% Ar; for sensitization experiments, 2.0% 

s(>2/0.5% H2/10.0% 02/87.5% Ar and 3.0% SO2/0.5% Hz/lO.O% 02/86.5% Ar. 

Experimental 

The shock tube-laser absorption technique is described in detail el~ewhere.~ Briefly, the test 

section of the shock tube was routinely pumped below 3 p Torr by a Varian V60 Turbopump. 

The combined leak and out-gassing rate of the test section was 5 p, Torr min-'. All shocks were 

initiated within 1 minute of admitting the test gas mixture. Shock velocities were measured using 

4 flush-mounted 1 13A2 1 PCB Piezotronics pressure transducers coupled to Phillips PM6666 

programmable counter-timers. The last pressure transducer was axially coincident with the center 

of the observation windows, 12.7 mm distant from the end wall. Shock speeds were fitted to a 

second-order polynomial in distance. The extrapolated speed to the end wall was used together 

with NASA thermodynamic data' in solving the standard relationships for the reflected shock 

properties, assuming full vibrational relaxation and no chemical reaction at the shock front. The 

computed reflected shock properties were corrected for boundary layer interaction effects using 

the similar method of Michael and S~therland.~~*'~ 

The combined OH and SO2 absorption profiles were measured at 3 10.032 nm (in air), 

corresponding to the Pl(5) line of the (0,O) band of the OH A C t X2 ll transition-at this 

wavelength, SO2 also shows some absorption. The UV light was produced by a CW argon ion 

laser (Coherent Innova 200) pumped ring-dye laser (Coherent 899 - 2 1) running Kiton Red 620 

dye. Intracavity frequency doubling was achieved with an angle tuned LiI03 crystal. For the 

detection of OH radicals and SO2 molecules, a triple beam scheme was employed; probe beam, 

intensity reference beam and a wavelength reference beam (through a burner-stabilized 

methanelair flame). The detector was a combination of interference filter (3 10 nm with 10 nm 

fivhm)-PMT(Thorn EMI9924QBbhigh speed buffedamplifier. The S/N of the "probe beamintensity reference beam" was usually better than 100. The overall electronic time constant 

determined for the entire PMT-buffer-cable system was less than 0.5 p s. 

2+ 

H2/02/Ar and S02/H2/02/Ar test gas mixtures were prepared manometrically and allowed to 

stand for 48 hr before use. Gases were used without further purification. The stated purities were: 

H2,99.9995% (MG Industries, Scientific Grade); 02, 99.998% (MG Industries, Scientific 

Grade); SO2 (anhydrous), 99.98 wt.% (MG Industries, Scientific Grade); Ar, 99.9999% (MG 

Industries, Sputtering Grade). 

NASAICR-2003-2 12293 3 
Results 

Because 3 10 nm UV light is also absorbed by SO2 molecules, it is necessary to determine 

absorption coefficients of SO2 (E e(SO2). The values of E e(SO2) determined are shown in Figure 

3. A least squares fit to the data gives an expression 

(S02)=2.16x IO5 exp(-765.0 IUT) cm2 mol-' 

Evaluation of a characteristic time ( z 50) in the baseline experiments was done in the usual way. 

However, in the sensitization experiments, because there have always been long delays for 

sensible absorption signal rise (OH production), initial absorption by SO2 immediately after the 

reflected shock was subtracted from the total absorption signal and z 50 values were evaluated as 

in the baseline experiments. Figure 4 shows z 50 values measured for the baseline mixture, 0.5% 

H2/10.0% 02/89.5% Ar, and for the sensitization mixtures, 2.0,3.0% S02/0.5% H2/10.0% 

02B6.5, 87.5% Ar. Throughout all of the experiments, densities were kept nearly the same 

between the baseline and sensitization experiments. 

As seen in the figure, the z 50 values of sensitization mixtures are longer at low temperatures and 

increase with S02/H2 ratio. At temperatures above 1200 K, the differences disappear between the 

two levels of sensitization. 

Discussion 

H2/02 System 

Because we generated 0-atoms from the H2/02 reaction system, a complete understanding of the 

H2/02 reaction chemistry is a prerequisite for rate coefficient determination of the O+S02+M -+ 

SO3+M reaction (R2 1). There are three key reactions in H2/02 chemistry: chain branching H+O2 

+ OH+O (Rl), chain propagating O+H2 + OH+H (R2) and chain terminating H+02+M + 

H02+M (R9). A comprehensive review of these three reactions is given here. 

(a) Chain Branching H+O2 + OH+O (R1) 

Figure A( 1) in Appendix A shows the rate coefficient expressions reported recently. The current 

widely used rate coefficient expressions are those of Du and Hessler," Baulch et al." and GRI.12 

Du and Hessler obtained their kl expression, kl=9.76x 1013 exp(-7474 K/T) cm3 mol-' ~~'(960 to 

5300 K) by combining their rate coefficient measurements at very high temperatures (3450 to 

5300 K) with the results of Masten et al.13 (1450 to 3370 K), Shin and Mi~hael'~ (1 103 to 2055 

K) and Pirraglia et ai? (962 to 1705 K). The compilation by Baulch et al. gives an expression 

identical to that of Du and Hessler. Pirraglia et al. combined their relatively low temperature 

results with the high temperature data of Frank and JustI6 (1693 to 2577 K) and reported 

kl=1.9x 1014 exp(4272 K/T) cm3 mol-' s-' (962 to 2577 K). The GRI expression, kl=2.65x 10l6 

exp(4575 WT) cm3 mol-' s-' (300 to 3000 K) is a fit to the combined high temperature 

results of Yu et al.I7 (which, in turn, the results of Yuan et a1.I8 and of Masten et al.) and the 

somewhat low rate coefficients of Pirraglia et al. (especially low temperature data) with the room 

temperature data compiled by Demore et Previously, we (GRC)' reported kl=7.13 x 1013 

T -0.6707 

NASNCR-2003-2 12293 4 
exp(-6957 WT) cm3mol-'s-' (1 050 to 2500 K) based upon OH radical growth rate that 

eliminates any H-atom producing contaminant effect. 

Since the A fff(298.15 K) value of OH has been remeasured (see above), virtually all kl values 

must be reexamined. Hence, with the new thermodata of OH we reevaluated our existing data. 

The rederived expression is kl=3.74x lOI5 T -0.467 exp(-7758 KiT) cm3 mol-' s-'. Extrapolation 

of this expression to room temperature gives about a factor of 2.5 higher than the value 

recommended by Demore et al. As seen, this expression has a negative temperature dependence 

of the A-factor. The temperature dependence of the A-factor has been given by several authors: 

-0.907 by Schott?' -0.927 by Yuan et a1.,'*-0.7 by Masten et 

theoretical calculations of Miller2' and Miller and 

and -0.816 and +OS00 by 

respectively. 

Due to the difficulty in performing experiments at relatively low temperatures, no group has 

exitended their temperature range wide enough to obtain a consistent set of experimental data. 

Instead, the results of Pirraglia et al. (960 to 1200 K) have been extensively used for the fit of the 

kl expression by various authors. Recently we measured OH absorption profiles in various H2/02 

systems at temperatures down to 950 K and up to 3500 K. We are currently analyzing these 

results. A combination of these new results with the previous ones reported in this laboratory' 

will form a consistent set of data over the widest temperature range (950 to 3500 K) ever 

employed by a single laboratory. Based upon this data set, a new rate coefficient expression will 

be produced and the validity of its temperature dependence of the A-factor and the extrapolated 

value to room temperature will be tested. 

(b) Chain Propagating O+H2 + OH+H (R2) 

SO2 molecules in the SO2/H2/O2 system are consumed mainly by O+S02+M + S03+M (R21). 

The chain propagating reaction R2 inherently competes with R2 1 for 0-atoms. Figure A(2) in 

Appendix A shows representative k2 expressions published. Previously we presented 

k2==1.87~ 1014 exp(-6854 WT) cm3 mol-' s-' (1420 to 2430 K). Reevaluation of OH absorption 

data obtained for k2 evaluation with the new OH thermodata yielded k2=2.04 x 1 014 exp(-6972 

WT) cm3 mol-' s-'. The differences between the old and new expressions are less than 3.5% in 

the given temperature range, the new expression being higher with temperature. One notable 

expression for k2 is that of Sutherland et Sutherland et al. reported a non-Arrhenius type ra 

coleficient expression, k2=5.06x lo4 T 2.67 exp(-3480 K/T) cm3 mol-' s-' by combining their 

results of flash photolysis-shock tube work (880 to 2495 K) and the flash photolysis-resonance 

e 

flu.orescence technique (504 to 923 K) with the low temperature data of Presser and Gordon (297 

to 471 K).24 Our k2 expression represents the high temperature data (880 to 2495 K) of 

Sutherland et al. quite well. However, due to the nature of a non-Arrhenius type curve fit, the 

ex-tended temperature fit of Sutherland et al. over-predicts their results at temperatures around 

950 K and above 2500 K. Therefore, in our temperature range (950 to 1100 K), extrapolation of 

our expression should be more appropriate. 

(c) Chain Terminating H+02+M + H02+M (R9) 

Th.e chain terminating R9 reaction plays a governing role for ignition and flame characteristics at 

high pressure and especially at low temperature conditions (see sensitivity spectra in Figure 2). 

NASAICR-2003-2 12293 5 
investigated this reaction to determine rate coefficients. 1,2542 For this reason, many authors 

Experimental data and k9 expressions are plotted in Figure A(3). At room temperature a 

consensus value has been e~tablished.~~ However, in the temperature range of combustion 

(P750 K), the scatter of rate coefficient data is very large. For example, at T-1000 K, there is 

a factor of 3 scatter in the ks values. We performed a series of experiments to determine the ks 

values in the temperature range of 950 to 1150 K using a shock tube-laser OH absorption 

spectroscopy technique in H2/02 system. Experimental data were fit to k9=3.75 x 1OI7 T -o.7 cm6 

molp2 s-'. Our values positioned somewhat in the middle of the data scatter at T=-1000 K. 

Extrapolation of our ks expression also well represents the data of Hsu et 

between 296 K and 640 K and the room temperature result of Carleton et al.33 

at temperatures 

S02/H2/02 System 

As mentioned before, sensitization was used with 2% and 3% S02. Sensitization resulted in a 

remarkable increase of z 50 (see Figure 4). The effect of sensitization level on z 50 becomes more 

noticeable as temperature decreases, but it diminishes as temperature increases. Nevertheless, 

this increase of z 50 is due to depletion of 0-atoms by R2 1, so the H-atom production rate by R2 

is reduced. This, in turn, reduces the branching rate of R1. 

The rate coefficients of R2 1 are derived by computer simulation using the Table I mechanism in 

Appendix A. In computer simulation, at each experimental condition, only the starting k21 value 

was varied so as to minimize the difference between the computed and experimental z 50. Figure 

5 shows the provisional k21 values obtained in this work. R2 1 is a pressure (density) dependent 

reaction. For this type of reaction, it is usual to use two rate coefficient expressions at the 

extreme conditions, a low pressure limit k21.0 and a high pressure limit k2l,=. The rate 

coefficients in the fall-off region are then obtained by interpolation using these two extreme rate 

coefficients. Obviously R2 1 is in the falloff region in our experimental conditions. Therefore we 

computed the starting k21 value using the k21,0, k21.00 ,and a simple Lindemann-Hinshelwood 

interpolation formula 

For k21,=and kzl,o,we used the expressions given by Mueller et 

K/T) cm3 mol-' s-' and by Tr0e,4~ k21,0=4.0X 

respectively. The k21, of Mueller et al. is the only high pressure limit expression ever reported. 

Several measurements of k21.0 have been reported either at high temperature~~~*~'(I435 to 2500 

K) or at low temperatures (<430 K). 19.47-50 In the temperature range of our interest (900 to 1100 

K), no experimental measurements are available. The k21.0 expression shown above was made by 

Troe by fitting the low and high temperature data. Note that at T400 K, the rate coefficient 

value increases with temperature (positive activation energy), while at T>500 K, it decreases 

with temperature (negative activation energy). Our provisional k21 values obtained in the falloff 

region are about a factor of 2 to 3 higher than the theoretical calculations using the equation 

shown above. 

k21.~0=9.2x 10" exp(-1200 

p.o exp(-2650 WT) cm' mol-2 s-I, 

NASNCR-2003-2 12293 6 
Conclusions 

Existing data for H2/02 and S02/H2/02 chemistry were critically reviewed and a reaction 

mechanism was assembled (Table I in Appendix A). Optimum H2/02/Ar and S02/H2/02/Ar 

mixture compositions and experimental conditions were established via a series of sensitivity 

analyses. Shock tube experiments were performed using OH laser absorption spectroscopy for 

the H2/02/Ar mixtures to examine baseline behavior and for the S02/H2/02/Ar mixtures to 

determine k21 values for the conditions selected. The experimental results were analyzed via 

computer simulations and the provisional rate coefficients of R2 1 were obtained. The provisional 

rate coefficients of R2 1 (k21 values) obtained in our experimental conditions are about a factor of 

2 to 3 higher than the theoretical calculations using the expressions of k21,0, k21,=, and the 

parameters of the interpolation formula in Table I of Appendix A. Additionally, temperature 

dependent absorption coefficients of SO2 at OH absorption wavelength were measured. 

Measured or calculated thermochemical and structural data for HS, HSO, HOSO, HS02, and 

H(3S02 species were critically reviewed and thermodynamic data for these species were obtained 

(Appendix B). 

Future Work 

In the second year of this project, besides what is contained in the project plan, the collision 

efficiency effect of SO2 the on pressure dependent reactions, R9 and R2 1, and the interpolation 

formula used in determination of k21 will be examined fbrther. In pressure dependent reactions, 

reaction rates increase with pressure. The increase of collision efficiencies of collision partners is 

equivalent to an increase of density (pressure). If one assigns a high collision efficiency of SO2 

to R9 and R2 1, their reaction rates and z 50 values will increase and result in a lowering of k21 

vailues. (Currently we used a collision efficiency of 1 for SO2 for R9 and R2 1 .) Experiments at 

valrious densities will also be performed to optimize the falloff parameters. Data analysis will be 

completed for the experiments performed to determine the rate coefficients of the chain 

branching reaction R1. 

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Gutman, D.; Hardwidge, E. A.; Dougherty, F. A.; Lutz, R. W.; J. Chem. Phys. 1967,47, 

5950. 

Pirraglia, A. N.; Michael, J. V.; Sutherland, J. W.; Klemm, R. B.; J. Phys. Chem. 1989, 

93,282. 

Davidson, D. F.; Petersen, E. L.; Rohrig, M.; Hanson, R. K.; Bowman, C. T.; TwentySixth Symposium (International) on Combustion; The Combustion Institute: Pittsburgh, 

PA, 1996; p 481. 

Ashman, P. J.; Haynes, B. S.; Twenty-Seventh Symposium (International) on Combustion; 

The Combustion Institute: Pittsburgh, PA, 1998; p 185. 

Mueller, M. A.; Kim, T. J.; Yetter, R. A.; Dryer, F. L.; Int. J. Chem. Kinet. 1999,32, 1 13. 

Hsu, K.-J.; Anderson, S. M.; Durant, J. L.; Kaufinan, F.; J. Phys. Chem. 1989,93, 1018. 

NASNCR-2003-2 12293 8 
33. 

34. 

35. 

36. 

37. 

38. 

39. 

40. 

41. 

42, 

43 * 

44. 

45. 

46. 

47. 

48. 

49. 

50. 

Carleton, K. L.; Kessler, W. J.; Marinelli, W.; J. Phys. Chem. 1993,97,6412. 

Kurylo, M. J.; J. Phys. Chem. 1972, 76,3518. 

Wong, W.; Davis, D. D.; Int. J. Chem. Kinet. 1974,2,401. 

Cobos, C. J.; Hippler, H.; Troe, J.; J. Phys. Chem. 1985,89,342. 

Clyne, M. A. A.; Thrush, B. A.; Proc. Roy. SOC. (London) 1963, A275,559. 

Hikida, T.; Eyre, J. A.; Dorfman, L. M.; J. Chem. Phys. 1971,54,3422. 

Westenberg, A. A.; deHaas, N.; J. Phys. Chem. 1972, 76,1586. 

Ahumada, J. J.; Michael, J. V.; Osborne, D. T.; J. Chem. Phys. 1972,57,3736. 

Bates, R. W.; Golden, D. M.; Hanson, R. K.; Bowman, C. T.; Phys. Chem. Chem. Phys. 

2001,3,2337. 

Michael, J. V.; Su, M.-C.; Sutherland, J. W.; Carroll, J. J.; Wagner, A. F.; J. Phys. Chem. 

A 2002,206,5297. 

Mueller, M. A.; Yetter, R. A.; Dryer, F. L.; Int. J. Chem. Kinet. 2000,32,317. 

Troe, J.; Ann. Rev. Phys. Chem. 1978,29,223. 

Ashtoltz, D. C.; Glanzer, K.; Troe, J.; J. Chem. Phys. 1979, 70,2409. 

Smith, 0. I.; Tseregounis, S.; Wang, S.-N.; Int. J. Chem. Kinet. 1982, 24,679. 

Atkinson, R.; Pitts, J. N., Jr.; Int. J. Chem. Kinet. 1978, 20, 1081. 

Mulcahy, M. F. R.; Steven, J. R.; Ward, J. C.; J. Phys. Chem. 1967, 72,2 124. 

Westenberg, A. A.; deHaas, N.; J. Chem. Phys. 1975,63,5411. 

Atkinson, R,; Baulch, D. L.; Cox, R. A.; Frank, P.; Hampson, R. F.; Kerr, J. A.; Rossi, M. 

J.; Troe, J.; J. Phys. Chem. Re$ Data 1997,26, 1329. 

NASAJCR-2003-2 12293 9 
ILog([i]N/[H,],)I vs. 4; i=O, OH and H 

T = loo0 K, p = 15.0 pmol cm -3 

-3-H 

0.5 

-2 -1.5 -1 -0.5 0 0.5 1 

Log(#) 

Figure 1 .-Absolute ratios of the peak concentrations of 0- and H-atoms and OH radicals to the initial concentration 

of Hz in the H2/02/Ar mixtures as a function of the mixture equivalence ratio, @ , evaluated at T=lOOO K and 

p =15.Opmol ~m-~. Large values indicate the suppression of peak concentrations. 

0.5% Hz, 10.0% Oz, 89.5% Ar 

T=1000 K, p=15.0 kmol ernJ 

-1 -0.5 0 0.5 1 1.5 

Sensitivity 

Figure 2(a).-Sensitivity spectra for ‘I: of the baseline mixture, 0.5% H2/10.0% 02/89.5% Ar. 

T=IOOO K and p =15.Opmol 

NASNCR-2003-2 12293 10 
2.0% Sq, 0.5% H2, 10.0% O,, 87.5% Ar 

T=1000 K, p=15.0 pol cm3 

0 HOSO+M=SO,+H+M 

L_l H+O,=OH+O 

-2 -1 0 1 2 3 

Sensitivity 

Figure 2(b).-Sensitivity spectra for Z 50 of the 2.0% SO2/O.5% H2/10.0% 02/87.5% Ar. 

T=lOOO K and p =15.0pmol ~m-~. 

Absorption Coefficients of SO, at 310 nm 

&,(S0,)=2.16 x lo5 exp(-765.0 KIT) cm2 mol-' 

13 

"# 12 

u . 

n 

11.5 

Y3 

0 

C 

Y 

10.5 

7.0 

I 

8.0 9.0 10.0 11.0 

10000 K/T 

Figure 3.-Base 'e' absorption coefficients of SOz at 3 10 nm. The least squares fit 

expression is E ,(S02)=2.16X lo5 exp(-765.O/T) cm2 mol-'. 

NASA/CR-2003-2 12293 11 
SO2IH2IO2IAr 

3.50 

3.25 

n v) 

1 3 3.00 

ma 

2.75 

a SO2/H2/O2/~0.0/0.5/1O.0/89.5, p=15.4 pol an-3 

9.0 9.5 10.0 10.5 

loo00 KIT 

Figure 4.-Measured Z 50 values of the baseline mixture. 0.5% H2/10.0% 02/89.5% 

Ar and two sensitization mixtures, 2.0% s02/0.5% H2/10.0% 02/87.5% 

Ar and 3.0% S02/0.5% H2/10.0% 02/86.5% Ar. 

0 + so, (+M) = so3 (+M) 

A SO2/H2/O2/Ar=2.0/0.5/1O.0/87.5. p=16.1 pnol ans3 

0 S02/H2/02/A1=3.0/0.5/1 0.0/86.5, p=15.9 pol an-; - theory, p=16.0 pol an-; 

9.0 9.5 10.0 

loo00 K/T 

Figure 5.-The falloff k2, values of the reaction R21, O+S02(+M) + SO,(+M). 

NASNCR-2003-2 12293 12 
Appendix A 

Table I.-Reaction Mechanismu 

- 

reaction A n 0 Note 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

H+02=OH+O 7.13E+13 

O+H2=OH+H 1.87E+14 

OH+H2=H+H20 2.16E+08 

O+H20=OH+OH 4.5 lE+04 

O+O+M=02+M l.OE+17 

Ar,l.O/H2,2.9/ 02,1.2/H20,18.5/ 

H+H+M=H2+M 6.4E+17 

Ar,1.0/ H2,4.0/ H20,12.0/ H,26.0/ 

H+O+M=OH+M 6.2E+ 16 

Ar,l.O/ H20,5.0/ 

H+OH+M=H20+M 8.4E+2 1 

Ar,1.0/ H2,2.5/ H20,16.25/ 

H+02+M=H02+M 7.55E+17 

Ar,1.0/ 02,1.33/H2,3.33/H20,21.3/ 

H02+H=OH+OH 1.5E+14 

H02+H=H2+02 2.5E+13 

H02+H=H20+0 5.OE+12 

H02+0=02+0H 2.OE+13 

H02+OH=H20+02 2.OE+ 13 

H02+H02=02+H202 1.3E+11 

H02+H02=02+H202 4.2E+14 

H202+M=OH+OH+M 1.2E+17 

Ar,0.67/ 02,0.78 / H20,6.0/ 

1 .ooo 

Ar,1.0/ 02,1.33/ S02,1.0/ 

S02+0H+M=HOS02+M 

0.640 

Ar,l.O/ 02,1.5/ S02,12.l/e 

HOSO+M=S02+H+M 

0.450 

1.7E+12 

l.OE+13 

2.8E+13 

7.OE+ 1 2 

9.2E+10 

4.0E+28 

1 .ooo 

7.2E+ 12 

4.5E+25 00 

1.7E+10 

1.6E+3 1 

0.0 

Ar,0.75/ H2,2.5/ H20,12.0/ 

S02+0H=S03+H 4.9E+02 

0.0 

0.0 

1.51 

2.70 

-1.0 

-1 .o 

-0.6 

-2.0 

-0.8 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

-4.0 

0.0 

0.0 

-3.3 

300.0 

0.8 

-4.53 00 

2.69 

6957 

6854 

1726 

732 

0 

0 

0 

0 

0 

505 

350 

710 

0 

0 

-820 

6039 

22900 

1900 

1805 

3225 

720 

1198 

2642 

0 

3 60 

360 

0 

23602 

24759 00 

11977 

e 

e 

e 

e 

e 

f 

f 

e 

b 

d 

e 

b 

d 

e 

b 

d 

e 

C 

C 

C 

NA.SA/CR-2003-2 12293 13 
Table I.-Reaction Mechanisma (continued) 

reaction A n 0 Note 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

SO+O+M=S02+M 3.2E+13 

2.9E+24 

0.550 0.0 

S03+O=S02+02 4.1 1E+1 I 

so~+so=so2+so2 l.OE+12 

S03+H20=H2S04 7.23E+08 

SO+OH+M=HOSO+M 8.OE+2 1 

SO+OH=S02+H 5.2E+13 

s0+02=s02+0 6.2E+03 

HOSO+OH=S02+H20 1.OE+12 

HOSO+02=S02+H02 1.OE+12 

HOS02+M=S03+H+M 3.2E+ 16 

HOS02+H=S02+H20 1.OE+12 

HOS02+0=S03+0H 5.OE+12 

HOS02+OH=S03+H20 l.OE+12 

HOS02+02=SO3+H02 7.8E+11 

Ar,1.00/02,1.33/ H20,10.0/ 

Ar,0.75/ H2,2.5/ H20,12.0/ 

HOSO+H=SO+H20 6.3E-10 

Ar,O.75/ H2,2.5/ H20,12.0/ 

0.0 

-2.9 

00 

0.0 

0.0 

0.0 

-2.16 

0.0 

2.42 

6.29 

0.0 

0.0 

-0.81 

0.0 

0.0 

0.0 

0.0 

0 b 

0 C 

00 d 

e 

3070 

2013 

0 

418 

0 

1535 

-956 

0 

503 

27024 

0 

0 

0 

330 

e 

e 

Rate coefficients are in the form, k = AT exp(- 0 f"). Units are K, cm, mol, and s. 

koo 

ko 

Falloff correction parameters. 

Collision efficiencies. 

b 

e 

'Duplicated reaction. 

NASNCR-2003-2 12293 14 
13.0 

n 

-7 

," 12.0 

P 

-a 

s gJ 11.0 

I 

0 

\ 

, 

c;l 

10.0 

11.5 

n 

v1 

- 

3 

.I 

P 

-a 11.0 

3 

0 

.+ 

s 

M 

10.5 

-GRC (ref.1) 

- -Yuetal, 1994(ref.2) 

- - Du and Hessler, 1992 (ref.3) 

- - - Shin and Michael, 1991 (ref.4) 

- - Pirraglia et al. 1989 (ref.5) 

- Frank and Just, 1985 (ref.6) 

- - - Baulch et al, 1994 (ref.7) 

2.0 4.0 6.0 8.0 10.0 12.0 

10000 KIT 

Figure Al(a).-Rate coefficients of R1, H+OZ + OH+O. 

H + 02 = OH + 0 

(Figure Al(b)) 

- GRC (ref.1) 

s - Yu et ai, 1994 (ref.2) 

- - Du and Hessler, 1992 (ref.3) 

- -Shin and Michael, 1991 (ref.4) 

- - Pirraglia et al. 1989 (ref.5) 

Baulch et ai, 1994 (ref.7) \ 

8.0 8.5 9.0 9.5 10.0 10.5 

loo00 WT 

Figure Al(b).-Exploded plot of the Figure Al(a) for the temperature range of 950 to 1250 K. 

NASNCR-2003-2 12293 15 
0 + Hz = OH + 0 

13.5 

-GRC (&.I) 

- - - Natarajan and Roth, extended fit. 1987 (ref 8) 

- Davidson and Hanson, 1990 (ref9) 

Baulch et al, 1994 (ref 7) 

e;l 

-%herland et al, extended fit. 1986 (ref IO) 

0 

12.0 

4.0 5.0 6.0 

loo00 KIT 

Figure AZ(a).-Rate coefficients of R2, O+Hz + OH+H. 

0 + H2 = OH + 0 

12.0 

0 Baulch et al, 1994 (ref.7) 

- - Sutherland et al, 880-2495 K, 1986 (ref.10) 

- - Sutherland et al, 504-923 K, 1986 (ref.10) 

10.5 - 

7.0 

8.0 9.0 10.0 11.0 

loo00 K/T 

12.0 

Figure AZ(b).-Exploded plot of the Figure A2(a) for the temperature range of 830 to 1250 K. 

NASNCR-2003-2 12293 16 
H + 02 + M=H02 + M 

10". 

- n 

'a 1Ol6 

c;' I 

z 

w0 

3 

0 

\ E 1015 

3 

1 014 

0 

rn 

A 

X 

0 

+ 

0 GRC, M=Ar (ref 1) 

0 

0 Kurylo (ref 19) 

-GRC, fit (ref 1) 

X 

0 

A 

+ 

X 

Getzinger and SchotI, M=Ar (ref 11) 

Getzinger adn Blair. M=Ar (ref 12) 

Gutman. et al, M=Ar (ref 13) 

Pirraglia et al, M=Ar (ref 5) 

Davidson et al, M=Ar (ref 14) 

Ashman and Haynes, M=Ar (ref 15) 

Mueller et al, M=Ar (ref 16) 

Hsu et al (ref 17) 

Carleton, et al (ref 18) 

Wong and Daws (ref 20) 

Cobos, et al (ref 21) 

Clyne and Thrush (ref 22) 

Hikida, et al (ref 23) 

Westenberg and deHass (ref 24) 

Ahumada, et a1 (ref 25) 

Bates et al. fit (ref 25) 

Michael et al. fit (ref 27) 1 

"4 

16.0 

yn 15.5 

c;' 

m 

I 

8" 

-3 N 

wz 15.0 

3 

M 

0 

4 14.5 

14.0 

8 12 16 20 24 28 32 36 40 44 48 52 

loo00 KIT 

Figure A3.-Rate coefficients of R9, H+02+M + HO,+M. 

0 + SO2 + M= SO,+ M 

-Deblore et al, 1997 (ref.28) 

-Smith - et al, 1982 (ref.29) 

Atkinson and Pas, 1978 (ref.30) 

Wcahy et al, 1967 (ref.31) 

-.roe, 1978 (ref.32) 

I Westenberfand deHaas, 1975 (ref.33) 

Atkinson et al, 1997 (ref.34) 

Ashtholz et al, 1979 (ref.35) 

0.0 10.0 20.0 30.0 40.0 50.0 

10000 KIT 

Figure A4(a).-Low pressure limit rate coefficients (k~~.~) of R21,O+SO*+M + S03+M. 

NASAICR-2003-2 12293 17 
1. 

2. 

3. 

4. 

5. I 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

10.75 

9.0 

I 

9.5 10.0 10.5 11.0 

loo00 KIT 

Figure A4(b).-High pressure limit rate coefficients (k2,,00) of R21, 0+S02 + SO3. 

References 

Hwang, S. M.; De Witt, K. J.; Rabinowitz, M. J.; This work 2002 

Yu, C.-L.; Frenklach, M.; Masten, D. A.; Hanson, R. K.; Bowman, C. T.; J, Phys. Chem. 

1994,98,4770. 

Du, H.; Hessler; J. P.; J. Chem. Phys. 1992,96, 1077. 

Shin, K. S.; Michael, J. V.; J. Chem. Phys. 1991,95,262. 

Pirraglia, A. N.; Michael, J. V.; Sutherland, J. W.; Klemm, R. B.; J. Phys. Chem. 1989, 

93,282. 

Baulch, D. L.; Cobos, C. J.; Cox, R. A.; Frank, P.; Hayman, G.; Just, Th.; Kerr, J. A.; 

Murrells, T.; Pilling, M. J.; Troe, J.; Walker, R. W.; Warnatz, J.; J. Phys. Chem. Re$ 

Data 1994,23,847. 

Frank, P.; Just, Th. Ber. Busen-Ges. Phys. Chem. 1985,89, 181. 

Natarajan, K; Roth, P.; Combust. Flame 1987, 70,267. 

Davidson, D. F.; Hanson, R. K.; Combust. Flame 1990,82,445. 

Sutherland, J. W.; Michael, J. V.; Pirraglia, A. N.; Nesbitt, F. L.; Klemm, R. B.; Twentyfirst Symposium (International) on Combustion; The Combustion Institute: Pittsburgh, 

PA, 1986; p 929. 

Getzinger, R. W.; Schott, G. L.; J. Chem. Phys. 1965,43,3237. 

Getzinger, R. W.; Blair, L. S.; Combust. Flame 1970,14, 5. 

Gutman, D.; Hardwidge, E. A.; Dougherty, F. A.; Lutz, R. W.; J. Chem. Phys. 1967,47, 

5950. 

. 

NASAJCR-2003-2 12293 18 
14. 

15.. 

16. 

d 

17. 

18. 

19. 

20. 

21. 

22. 

23. 

24. 

25. 

26. 

27. 

28. 

29. 

30. 

31. 

32. 

33. 

34. 

35. 

361. 

Davidson, D. F.; Petersen, E. L.; Rohrig, M.; Hanson, R. K.; Bowman, C. T.; TwentySixth Symposium (International) on Combustion; The Combustion Institute: Pittsburgh, 

PA, 1996; p 481. 

Ashman, P. J.; Haynes, B. S.; Twenty-Seventh Symposium (International) on Combustion; 

The Combustion Institute: Pittsburgh, PA, 1998; p 185. 

Mueller, M. A.; Yetter, R. A.; Dryer, F. L.; Twenty-Seventh Symposium (International) 

on Combustion; The Combustion Institute: Pittsburgh, PA, 1998; p 177. 

Hsu, K. -J.; Anderson, S. M.; Durant, J. L.; Kaufman, F.; J. Phys. Chem. 1989,93, 1018. 

Carleton, K. L.; Kessler, W. J.; Marinelli, W.; J. Phys. Chem. 1993,97,6412. 

Kurylo, M. J.; J. Phys. Chem. 1972, 76,3518. 

Wong, W.; Davis, D. D.; Int. J. Chem. Kinet. 1974, I, 401. 

Cobos, C. J.; Hippler, H.; Troe, J.; J. Phys. Chem. 1985,89,342. 

Clyne, M. A. A.; Thrush, B. A.; Proc. Roy. SOC. (London) 1963, A275,559. 

Hikida, T.; Eyre, J. A.; Dorfman, L. M.; J. Chem. Phys. 1971,54,3422. 

Westenberg, A. A.; deHaas, N.; J. Phys. Chem. 1972, 76,1586. 

Ahumada, J. J.; Michael, J. V.; Osborne, D. T.; J. Chem. Phys. 1972,57,3736. 

Bates, R. W.; Golden, D. M.; Hanson, R. K.; Bowman, C. T.; Phys. Chem. Chem. Phys. 

2001,3,2337. 

Michael, J. V.; Su, M.-C.; Sutherland, J. W.; Carroll, J. J.; Wagner, A. F.; J. Phys. Chem. 

A 2002,106,5297. 

DeMore, W. B.; Sander, S. P.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, 

C. J.; Ravishankara, A. R.; Kolb, C. E.; Molina, M. J.; Chemical Kinetics and 

Photochemical Data for use in Stratospheric Modeling; Evaluation No. 12; JPL 

Publication 97-4; JPL: Pasadena, CA, January 15, 1997. 

Smith, 0. I.; Tseregounis, S.; Wang, S.-N.; Int. J. Chem. Kinet. 1982, 14, 679. 

Atkinson, R.; Pitts, J. N., Jr.; Int. J. Chem. Kinet. 1978,10, 1081. 

Mulcahy, M. F. R.; Steven, J. R.; Ward, J. C.; J. Phys. Chem. 1967, 71,2124. 

Troe, J.; Ann. Rev. Phys. Chem. 1978,29,223. 

Westenberg, A. A.; deHaas, N.; J. Chem. Phys. 1975,63,5411. 

Atkinson, R,; Baulch, D. L.; Cox, R. A.; Frank, P.; Hampson, R. F.; Kerr, J. A.; Rossi, M. 

J.; Troe, J.; J. Phys. Chem. ReJ: Data 1997,26, 1329. 

Ashtoltz, D. C.; Glanzer, K.; Troe, J.; J. Chem. Phys. 1979, 70,2409. 

Mueller, M. A.; Yetter, R. A.; Dryer, F. L.; Int. J. Chem. Kinet. 2000,32,3 17. 

NASA/CR-2003-2 12293 19 
NASAICR-2003-2 12293 20 
Appendix B 

Hydroxysulfonyl (HOS02) 

Afp(298.15 K)-391.2 kJ mol-' 

0 

Vibrational Frequencies (cm-I) and Degeneracies: 

35 39.8 (1) 

1309.2 (1) 

1296.2 (1) 

1097.2 (1) 

759.3 (1) 

544 (1) 

491 (1) 

437 (1) 

2!52 (1) - torsion 

Ground State Quantum Weight: 2 ( 2A') 

Point Group: C1 

External Rotational Symmetry Number: o =1 

Bond Length (angstrom): 

r(?-0 1 )= 1.6 12 

r(15-02)=1.444 

r(S-03)=1.436 

r( 13 1 -H)=O. 967 

Bond Angle (degree): 

e (so 1 -HI= 1 07.2 

e (0 1 -s-o2)= 1 08 .4 

e(01-s-03)=106.0 

z (02-%01-H)=26.1 

~(03-S-Ol-H)=161.1 

114 3 Plroduct of the Moment of Inertia: I, I, Iz=l .473 x 10- 

Reduced Moment of Inertia: I, = 1.405 x 1 040 g cm2 

Internal Rotational Symmetry Number: n=2 

Barrier to Internal Rotation: Vo=9.5 kJ mol-' 

g cm6 

Enthalpy of Formation 

From Benson's estimate for D0298,~5(H(r-S02)=36f 3kcal mol-',l A@ (298.15 K) =409 kJ 

mol-' (-98 kcal mol-') was derived. This value of A fH0 (298.15 K) gives A rHO (298.15 K)=6 

kcal mol-' for the reaction, HOS02+02 + H02+ so3. 

h4argitan's rate coefficients measurement for the above reaction put an upper limit for the 

reaction endothermicity, ArH0 (298.15 K) I2 kcal mol-' (D0298.15(H(r-s02) I32 kcal mol ). 

Gleason and Howard set a limit on the endothermicity of the reaction (I), A 

-1 2 

(298.15 K) I 3 

NASNCR-2003-2 12293 21 
kcal mol-',3 which places a lower limit of A @ (298.15 K) 2-395.4 kJ mol-' (2-94.5 kcal mol- 

'). Here we adopted Margitan's value of A ,p (298.15 K) = 2 kcal mol-', which gives A @ 

(298.15 Kp391.2 kJ mol-' (-93.5 kcal mol-'). 

Heat Capacity and Entropy 

The molecular structure of HOS02 was taken from the results of MP2 level calculation with ccpVQZ basis set by Majumdar et The reduced moment of inertia, I,, for the hindered internal 

rotation was calculated by assuming HOS02 is essentially a cis form.4 This assumption sets the 

internal rotational symmetry number, n=2. The rotational barrier was calculated using the 

equation, 2 nco/n=(Vd21,)1/2, where c is the speed of light and ais the torsional frequency, 252 

cm-'. 

I 

Hashimoto et al. measured four vibrational frequencies of HOS02 in an argon matrix at I I K.' 

Nagase et al. confirmed the four vibrational frequencies using the same method of Hashimoto et 

al. and also calculated the geometry and vibrational frequencies at the unrestricted HF level with 

the 3-21G(*) basis set.6 Later, Kuo et al. measured vibrational frequencies of HOS02 in the 

argon matrix at 12 K.' The four frequencies reported by Hashimoto et al. and Nagase et al. were 

again confirmed. An additional frequency corresponding to HOS bend at 1296.2 cm-' was 

measured.' Here, we took five experimental frequencies (3539.8, 1309.2, 1296.2, 1097.2,759.3) 

of Hashimoto et al., Nagase et al. and Kuo et al. and four computed frequencies (544,491,437, 

252) of Nagase et al. for the derivation of heat capacity and entropy. 

References 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

Benson, S. W.; Chem. Rev. 1978, 78,23. 

Margitan, J. J.;J Phys. Chem. 1984,88, 3314. 

Gleason, J. F.; Howard, C. J.; J. Phys. Chem. 1988,92,3414. 

Majumdar, D.; Kim, G.-S.; Kim, J.; Oh, K. S.; Lee, J. Y.; Choi, W. Y.; Lee, S.-H.; Kang, 

M.-H.; Min, B. J.; J. Chem. Phys. 2000, 222,723. 

Hashimoto, S.; Inoue, G.; Akimoto, H.; Chem. Phys. Lett. 1984, 207, 198. 

Nagase, S.; Hashimoto, S.; Akimoto, H.; J. Phys. Chem. 1988,92,641. 

Kuo, Y.-P.; Cheng, B.-M.; Lee, Y.-P.; Chem. Phys. Lett. 1991,277, 195. 

NASNCR-2003-2 12293 22 
Hydroxysulfinyl (HOSO) 

A@(O K)-237.4 f 10 kJ mol-' 

Vibrational Frequencies (cm-') and Degeneracies: 

1351 (1) 

34.76 (1) 

1073 (1) 

764 (1) 

343 (1) 

200 (1) - torsion 

Ground State Quantum Weight: 2 ( 2A") 

Point Group: C, 

External Rotational Symmetry Number: o =1 

Bond Length (angstrom): 

r( SO 1 )= 1.66 1 

r(%02)=1.482 

r( 0 1 -H)=O. 9 83 

Bond Angle (degree): 

8 i(S-Ol-H)=106.9 

Product of the Moment of Inertia: I,I,Iz=2.539x 10- 

Reduced Moment of Inertia: Ir=l.585 x 1 04' g cm2 

Internal Rotational Symmetry Number: n=2 

Barrier to Internal Rotation: V0=7.9 kJ mol-' 

e I(o 1 -s-02)= 1 09. 8 

115 3 g cm6 

Enthalpy of Formation, Heat Capacity and Entropy 

The enthalpy of formation of HOSO and its geometry and vibrational frequencies have not been 

measured experimentally. The most reliable information is from theoretical calculations of 

Lalakso et al.' Laakso et al. optimized geometry and vibrational frequencies at the 

MP2=FULL/&3 1 G* level. Energies were obtained with G2 theory. For the enthalpy of 

formation, the changes in G2 energy for the reaction, HOSO -+ OH+SO (ArHO(0 K)=280.8 kJ 

mol-') was obtained and then A &(O K) of HOSO was derived using the measured A fHO(0 K) 

values of OH and SO in the JANAF tables2 Laakso et al. proved the reliability of their 

calculation by comparing their G2 level A @(O K) for the reaction, HS+02 + OH+SO with that 

of the experimental value from the JANAF tables. Only a small difference in the reaction 

enthalpy, ArHO (0 K)= 0.3 kJ mol-' resulted. However, a recent measurement and quantum 

calculation of Do(OH, 0 K)3,4 gave A@ (OH, 0 K)=8.85 k 0.07 kcal mol-' (37.03 f 0.29 kJ mol- 

'). Thus the calculated ArHO(0 K) value for HS+02 + OH+SO reaction by Laakso et al. would 

be different from 0.3 kJ mol-'. Since Do(O K) for HOSO dissociation from Laakso et al. is the 

only available value, we adopted this value and calculated the enthalpy of formation of HOSO 

using the newly measured A fHO of OH and NASA value of SO at 0 K. The recommended 

enthalpy of formation of HOSO is A @ (HOSO, 0 K)= A @(OH, 0 K)+ A @(SO, 0 KF 

NPiSA/CR-2003-2 12293 23 
279.2=37.03+4.7143-279.2 kJ mol-'-237.4f 10 W mol-' (-56.7f 2.4 kcal mol-') with an error 

bound given by Laakso et al. 

For the derivation of heat capacity and entropy we took the molecular geometry and vibrational 

frequencies of Laakso et a]. The barrier to internal rotation (v0=7.9 kJ mol-') was directly taken 

from Laakso et al.'s computed G2 barrier for cis to trans transition of HOSO. 

References 

1. 

2. 

3. 

4. 

Laakso, D.; Smith, C. E.; Goumri, A.; Rocha, J.-D. R.; Marshall, P.; Chem. Phys. Lett. 

1994,227,377. 

Chase, M. W., Jr.; Davis, C. A.; Downey, J. R.; Frurip, D. J.; McDonald, R. A.; Syverud, 

A. N.; J. Phys. Chem. Re$ Data 1985,14, Suppl. 1. 

Ruscic, B.; Feller, D.; Dixon, D. A.; Peterson, K. A.; Harding, L. B.; Asher, R. L.; 

Wagner, A. F.; J. Phys. Chem. A 2001,105, 1. 

Ruscic, B.; Wagner, A. F.; Harding, L. B.; Asher, R. L.; Feller, D.; Dixon, D. A.; 

Peterson, K. A.; Song, Y.; Qian, X.; Ng, C.-Y.; Liu, J.; Chen, W.; Schwenke, D. W.; J. 

Phys. Chem. A 2002,106,2727. 

Sulfinyl (HS02) 

Af@ (298.15 KPl78.2f 8.4 kJ mol-' 

Vibrational Frequencies (cm-*) and Degeneracies: 

2269 (1) 

1600 (1) 

1128 (1) 

1065( 1) 

810 (1) 

431 (1) 

Ground State Quantum Weight: 2 (2A') 

Point Group: C, 

External Rotational Symmetry Number: 0 =1 

Bond Length (angstrom): 

r(S-0 1 )= 1.447 

r(S-02)=1.447 

r(H-02)=1.381 

Bond Angle (degree): 

e (oi-s-02)=123.2 

e (H-S-O~)=IO~.~ 

~(H-S-02(01))=121.1 

115 3 Product of the Moment of Inertia: I, I, Iz=l.485 x 10- g cm6 

NASNCR-2003-2 12293 24 
Enthalpy of Formation 

Banson's estimate for the enthalpy of formation of HS02 was A fff(298.15 K)-l77.4 f 16.7 kJ 

mol-' (-42.4f 4 kcal mol-'). The corresponding 0'298 15(H-S02)=41 kcal mol-' was compatible 

with the fast rate coefficients measured in flame studies at P1600 K for the three-body 

recombination reaction (H+S02+M=HS02+M).' Boyd et al. performed ab initio calculations for 

HSO2 at the HF/STO-3G* leveL2 Using the calculated 0'0(H-S02)=142. 1 kJ mol-' and the 

A &(O K) values of H and SO2 in the JANAF tables: A @(O K)-220.4 kJ mol-' (-52.7 kcal 

mol-') was derived for HS02. Laakso et al. optimized geometry and vibrational frequencies for 

HS02 at the MP2=FULL/6-3 lG* level.4 Energies were obtained with G2 theory. For the 

enthalpy of formation, the change in G2 energy for the reaction, HS02 + H+SO2 ( A J?(O 

K)=56.8 k 10 kJ mol-') was obtained and then A fP(0 K) of HS02 was derived using the 

measured A fP(0 K) values of H and SO2 in the JANAF tables. A fp(298.15 K) of HS02- 

141.4f 10 kJ moT1(-33.8f 2.4 kcal mol-') was recommended. Laakso et al. proved the 

reliability of their calculation by comparing their G2 level A rg(O K) for the reaction, HS+02 + 

Hi-SO2 with that of the experimental value from the JANAF tables. Considering the error limit in 

the G2 ArHO(0 K) value, the difference in the reaction enthalpy,A@(O K)=9.4 kJ mol-' was 

considered excellent. Recently, Denis and Ventura investigated the enthalpy of formation of 

XSO2, X=H, CH3 using the B3LYP and B3PW91 methods with very large basis sets up to ccpV 6Z.5 The enthalpy of formation of HS02, A fg(298.15 K)-l78.2 f 8.4 kJ mol-' (-42.6 f 2 

kcal mol-') resulting from B3PW91 method was recommended. We adopted the enthalpy of 

formation of Denis and Ventura, A fg(298.15 K)-178.2 f 8.4 kJ mol-' for HS02. 

Heat Capacity and Entropy 

Vibrational frequencies of HS02 have not been measured experimentally and only one 

theoretical calculation is available. For the derivation of heat capacity and entropy we used the 

vitlrational frequencies calculated at the MP2=FULL/6-3 1 G* level by Laakso et a1.4 The 

mdecular geometry was taken from the theoretical calculation using the B3PW91 method with 

cc--pV6Z basis set by Denis and Ventura.' 

References 

1. 

2. 

3. 

4. 

5. 

Benson, S. W.; Chem. Rev. 1978, 78,23. 

Boyd, R.; Gupta, A.; Langler, R. F.; Lownie, S. P.; Pincock, J.; Can. J. Chem. 1980,58, 

331. 

Chase, M. W., Jr.; Davis, C. A.; Downey, J. R.; Frurip, D. J.; McDonald, R. A.; Syverud, 

A. N.; J. Phys. Chem. Re$ Data 1985,14, Suppl. 1. 

Laakso, D.; Smith, C. E.; Goumri, A.; Rocha, J.-D. R.; Marshall, P.; Chem. Phys. Lett. 

1994,227,377. 

Denis, P. A.; Ventura, 0.; Chem. Phys. Lett. 2001,344,221. 

NASAICR-2003-2 12293 25 
Mercapto (SH) 

AfIf(0 KF133.03 kJ mol-' 

Enthalpy of Formation 

The current JANAF recommendations for A &(O Kpl36.49 k 5.0 kJ mol-' and A fp(298.15 

Kpl39.33 f 5.0 kJ mol-' are based on the measurements of HS ionization potential and the 

appearance potential of HS' from photoionization of H2S.' The previous NASA recommendation 

for A fp(298.15 K)2 was also 139.33 kJ mol-'. Continetti and Lee3 performed photodissociation 

of H2S at 193.3 nm using H-atom photofragment-translational spectroscopy with mass 

spectroscopic detection. They found D0o(H-Sp349.27 f 2.89 kJ mol-' (83.48 f 0.69 kcal mol-') 

in the secondary photodissociation of HS radicals, formed in the primary H2S photodissociation 

experiments. Nicovitch et 

Br(2P3,2)+H2S=HS+HBr over the temperature range of 3 19 to 43 1 K. Using both the "second law 

method" and the "third law method," an average value of A,@ at a given temperature was 

obtained, then the values of A rH(0 K) and A rP(298.15 K) were calculated by applying heat 

capacity corrections from data in JANAF tables for Br, H2S, HS and HBr. The reported values 

for the enthalpy of formation and the bond dissociation energy are A@(O K)=142.55 f3.01 kJ 

mol-' (34.07k0.72 kcal mol-'), Afp(298.15 KF143.01 k2.85 kJ mol-' (34.18k0.68 kcal mol- 

') and Doo(H-S)=348.23 k3.26 kJ mol-'(83.23 k0.78 kcal mol-'), Do298.15(H-S)=351.96&3.10 

kJ mol-' (84.12 f0.74 kcal mol-'), respectively. We adopted the bond dissociation energy of 

Continetti and Lee, Doo(H-S)=349.27 k2.89 kJ mol-' (83.48 f0.69 kcal mol-') and derived 

kcal mol-'). 

s 

measured the forward and reverse reaction rate coefficients of 

I AfIf(0 K)=Aflfo(S)+ A fh?o(H)-349.27=270.5 126+211.8014-349.27=133.03 kJ mol-' (3 1 .SO 

References 

1. 

2. 

~ 

~ DC, 1993. 

3. 

4. 

Chase, M. W., Jr.; Davis, C. A.; Downey, J. R.; Frurip, D. J.; McDonald, R. A.; Syverud, 

A. N.; J. Phys. Chem. Re$ Data 1985,14, Suppl. 1. 

Mcbride, B. J.; Gordon, S.; Reno, N. A.; Coeflcients for Calculating Thermodynamic 

and Transport Properties of individual Species; NASA TM-45 13; NASA: Washington, 

Continetti, R. E.; Balko, B. A.; Lee, Y. T.; Chem. Phys. Lett. 1991,182,400. 

Nicovich, J. M.; Kreutter, K. D.; van Dijk, C. A.; Wine, P. H.; J. Phys. Chem. 1992,96, 

25 18. 

Hydrogen Sulfur Oxide (HSO) 

I A&IO(O Kp3.8 kJ mol-' 

~ 

Vibrational Frequencies (cm-') and Degeneracies: 

2480 (1) 

1164 (1) 

1026 (1) 

NASNCR-2003-2 12293 26 
Ground State Quantum Weight: 2 (2A") 

Point Group: Cl 

External Rotational Symmetry Number: s= 1 

Bond Length (angstrom): 

r(S-O)=l.494 

L r(S-H)=1.389 

Bond Angle (degree): 

Product of the Moment of Inertia: I,I,IZ=5.O28x 10- 

. 

0 I:H-S-0)=106.6 

117 3 g cm6 

Enthalpy of Formation 

Schurath et al.' measured the chemiluminescence spectrum of the X2A" t A2A' transition of 

HSO and DSO. The A rIf(298.15 K) for the reaction HS+03 + HS0+02 (HS+O3 + 

H5;0*+02, HSO* + HSO) was estimated using the observed highest level of HS-0 vibration, 

v '3=7, which corresponds to 19149 cm-' (54.74 kcal mol-'). Using-A,If(298.15 K)I54.74 

kcid mol-' and the values of the enthalpy of formation of HS and O3 available, Schurath et al.' set 

an upper limit of AfIf(298.15 K)I 14.9 kcal mol-'. White and Gardiner' reanalyzed the results 

of Schurath et al. and presented 12.2 AfIf(298.15 K)<14.1 kcal mol-'. Benson's estimate3 was 

A @(298.15 K)=5 f 4 kcal mol-' Slagle et 

based upon their kinetic work on the reaction 0(3P)+H2S + HSO+H. Davidson et ai? studied 

the reactive scattering of 0 atoms with H2S molecules using a crossed molecular beam mass 

spectrometric detection of HSO radicals. The value of the enthalpy of formation obtained was 

A fp(298.15 K)-1.4 f 1.9 kcal mol-' (-6 f 8 kJ mol-'). Balucani et a1.6 determined A fIf(0 K) 

-0.9 k 0.7 kcal mol-' (-3.8 f 2.9 kJ mol-') from the analysis of high resolution crossed beam 

reactive scattering experiments on the reaction 0(3P)+H2S + HSO+H. Here we took Balucani 

et id.'S value A fIf(0 Kp0.9 f 0.7 kcal mol-' (-3.8 k 2.9 kJ mol-'). 

suggested A fIf (298.15 K)-3 kcal mol-', 

Heat Capacity and Entropy 

The molecular geometries and vibrational frequencies of HSO and DSO radicals were 

determined by Schurath et al.,' Kakimoto et 

of Schurath et al., Kakimoto et al. and Ohashi et al. observed the doppler-limited dye laser 

excitation spectra of the A2A'(003) t X2A"(O0O) vibronic transition of HSO and DSO. Here we 

took the structural parameters of HSO fiom those of Ohashi et ai. and Kakimoto et al., instead of 

the "best fit" values used in vibronic band contour synthesis by Schurath et al. The product of 

moment of inertia, I, I, I,, was calculated using the directly measured rotational constants, B,, By, 

and B, of Ohashi et al. 

and Ohashi et a1.' Following the measurements 

The three ground state (2A") vibrational frequencies, H-SO stretching (a]), H-S-0 bending 

(09, and HS-0 stretching (03), were presented by Schurath et al.' From v '3 progression, 03 

(1 0 13 cm-') was measured. The quantity 02 was estimated (1 063 cm-') using the measured 

bending frequency of DSO and the isotope factor. For 01, the recommended-S-H group 

frequency (2570 ~m-')~ was assigned. However, the harmonic force field analysis by Ohashi et 

al." yielded 02=1164 cm-' and 03=1026 cm-I. The force constant, kl, was estimated by applying 

1 

NASNCR-2003-2 12293 27 
2+ Badger's rule using the bond lengths and force constants of HS(2 ll ) and HS( C ) as references. 

From this estimated force constant 03 1=227 1 cm-' was calculated. 

Here we adopted 032=1164 cm-' and 033=l026 cm-' of Ohashi et al. We believe the 031 value 

from-S-H group frequency is too high and that of Ohashi et al. is too low. Therefore we 

estimated the 031 value in the following manner: Using the known H-0 and H-00 stretching 

frequencies the force constant change from H-0 to H-00 was calculated. For H-00 stretching 

the force constant was reduced by 15% from that of H-0. Since HS and HSO are isovalent 

radicals of HO and HOO, respectively, we calculated the force constant of H-SO by applying the 

same 15% reduction to the H-S force constant. The 03 1 value was calculated to be 

a,=( 112 n c)(kllmH)'"=2480 cm-', where c is the speed of light and mH is the mass of the 

terminal H atom. 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

References 

Schurath, U.; Weber, M.; Becker, K. H.; J. Chem. Phys. 1977,67, 110. 

White, J. N.; Gardiner, W. C., Jr.; Chem. Phys. Lett. 1978,58,470. 

Benson, S. W.; Chem. Rev. 1978, 78,23. 

Slagle, I. R.; Baiocchi, F.; Gutman, D.; J. Phys. Chem. 1978,82, 1333. 

Davidson, F. E.; Clemo, A. R.; Duncan, G. L.; Browett, R. J.; Hobson, J. H.; Grice, R.; 

Mol. Phys. 1982,46,33. 

Bafucani, N.; Casavecchia, P.; Stranges, D.; Volpi, G. G.; Chem. Phys. Lett. 1993,211, 

469. 

Kakimoto, M.; Saito, S.; Hirota, E. J.; Mol. Spectrosc. 1980,80,334. 

Ohashi, N.; Kakimoto, M.; Saito, S.; Hirota, E. J.; Mol. Spectrosc. 1980,84,204 

Herzberg, G. ; Molecular Spectra and Molecular Structure II. Infiared and Raman 

Spectra of Polyatomic Molecules; Van Nostrand: New York, 1945. 

NASAJCR-2003-2 12293 28 
1. AGENCY USE ONLY (Leave blank) 

National Aeronautics and Space Administration 

Washington, DC 20546-0001 

2. REPORT DATE 3. REPORT TYPE AND DATES COVERED 

April 2003 Annual Contractor Report 

NASA CR-2003-212293 

4. TITLE AND SUBTITLE 

Sulfur Oxidation and Contrail Precursor Chemistry 

6. AUTHOR(S) 

Kenneth J. De Witt 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

University of Toledo 

Department of Chemical Engineering 

2801 W. Bancroft St. 

Toledo, Ohio 43606 

B. SPONSORlNGlMONlTORlNG AGENCY NAME(S) AND ADDRESYES) 

I 

11. SUPPLEMENTARY NOTES 

5. FUNDING NUMBERS 

WU-708-8 7-23-00 

NAG3-2674 

8. PERFORMING ORGANIZATION 

REPORT NUMBER 

E-13855 

10. SPONSORlNGlMONlTORlNG 

AGENCY REPORT NUMBER 

Project Manager, Marty J. Rabinowitz, Turbomachinery and Propulsion Systems Division. NASA Glenn Research 

17. SECURITY CLASSIFICATION 18. SECURITYCLASSIFICATION 19. SECURITY CLASSIFICATION 

OF REPORT OF THIS PAGE OF ABSTRACT 

Unclassified Unclassified Unclassified 

Center, organization code 5830,216433-5847. 

20. LIMITATION OF ABSTRACT 

12a. DlSTRlBUTIONlAVAlLABlLlTY STATEMENT 

Unclassified -Unlimited 

Subject Categories: 01 and 07 Distribution: Nonstandard 

Available electronically at m://gltrs.grc.nasa.gov 

This publication is available from the NASA Center for Aerospace Information, 301-6214390. 

13. ABSTRACT (Maximum 200 words) 

12b. DISTRIBUTION CODE 

Sulfuric acid (H2S04), formed in commercial aircraft operations via fuel-S + SO, + SO, + H,SO,, plays an 

important role in the formation of contrails. It is believed that the first step occurs inside the combustor, the second step 

in the engine exit nozzle, and the third step in the exhaust plume. Thus, measurements of the sulfur oxidation rates are 

critical to the understanding of contrail formation. Field measurements of contrails formed behind commercial aircraft 

indicate that significantly greater conversion of fuel-bound sulfur to sulfate aerosol occurs than can be explained by our 

current knowledge of contrail physics and chemistry. The conversion of sulfur from S(IV) to S(V1) oxidation state, 

required for sulfate aerosol formation, is thermodynamically favored for the conditions that exist within jet engines but 

is kinetically disfavored. The principal reaction pathway is O+SO,+M + SO,+M. The rates of this reaction have never 

been measured in the temperature and pressure regimes available to aircraft operation. In the first year (FY02) of this 

project, we performed a series of experiments to elucidate the rate information for the O+S02+M + S03+M reaction. 

The work performed is described below, following the proposed work plan. Because we used the H,/O, system for an 

0-atom source and rate coefficients were obtained via computer simulation, construction of a reaction mechanism and 

either recalculation or estimation of thermodynamic properties of H,SO, species are described first. 

14. SUBJECT TERMS 115. NUMBER OF PAGES 

Sulfur oxidation; Contrail formation 

34 

16. PRICE CODE