Thermal Decomposition of COS

Oya, Masaaki; Shiina, Hiroumi; Tsuchiya, Kentaro; Matsui, Hiroyuki

doi:10.1246/bcsj.67.2311

Cited by 29 publications

(33 citation statements)

References 6 publications

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“…2 in which lines of various types are drawn for only the range of temperature investigated. Our data of k 1 increase from ͑2.7± 0.5͒ ϫ 10 −15 cm 3 molecule −1 s −1 at 298 K to ͑1.04± 0.19͒ ϫ 10 −12 cm 3 molecule −1 s −1 at 985 K, showing a distinct deviation from a linear Arrhenius form, but connecting satisfactorily data for T Ͼ 860 K by Shiina et al, 1 Oya et al, 2 and Woiki et al 3 and those for T = 233-445 K by Klemm and Davis. 6 Fitting our results alone yields an expression for the rate coefficient in the range of 298ഛ T /Kഛ 985:…”

Section: A Experimental Rate Coefficient Below 250 Torrsupporting

confidence: 90%

“…When combined with data for T Ͼ 860 K reported by Oya et al, 2 Woiki et al, 3 and those for T = 233-445 K by Klemm and Davis., 6 we derive a general expression k 1 ͑T͒ = ͑6.63 ± 0.33͒ ϫ 10 −20 T 2.57±0. 19 ϫexp͓− ͑1180 ± 120͒/T͔ cm 3 molecule −1 s −1 ,…”

Section: A Experimental Rate Coefficient Below 250 Torrmentioning

confidence: 85%

“…Measurements of the rate coefficient k 1 at temperatures above 860 K using a shock tube and atomic absorption [1][2][3][4] yield results somewhat consistent with the activation energy, with E a / R in the range of 3400-4560 K and the Arrhenius preexponential factor A in the range of ͑39-100͒ ϫ 10 −12 cm 3 molecule −1 s −1 , except an earlier experiment that employed a shock tube with mass spectrometric product detection and yielded an erroneously small value of k 1 = 1.0ϫ 10 −12 cm 3 molecule −1 s −1 at 2570 K. 5 In contrast, reported rate coefficients near 298 K using various detection methods differ significantly, in a range of ͑0.2-54͒ ϫ 10 −15 cm 3 molecule −1 s −1 . [6][7][8][9] Table I summarizes rate coefficients reported for this reaction.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and theoretical investigation of rate coefficients of the reaction S(P3)+OCS in the temperature range of 298–985K

Lee

et al. 2006

The Journal of Chemical Physics

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The reaction S(3P)+OCS in Ar was investigated over the pressure range of 50-710 Torr and the temperature range of 298-985 K with the laser photolysis technique. S atoms were generated by photolysis of OCS with light at 248 nm from a KrF excimer laser; their concentration was monitored via resonance fluorescence excited by atomic emission of S produced from microwave-discharged SO2. At pressures less than 250 Torr, our measurements give k(298 K)=(2.7+/-0.5)x10(-15) cm3 molecule-1 s-1, in satisfactory agreement with a previous report by Klemm and Davis [J. Phys. Chem. 78, 1137 (1974)]. New data determined for 407-985 K connect rate coefficients reported previously for T>or=860 and Tor=500 Torr, the reaction rate was enhanced. Theoretical calculations at the G2M(CC2) level, using geometries optimized with the B3LYP6-311+G(3df) method, yield energies of transition states and products relative to those of the reactants. Rate coefficients predicted with multichannel Rice-Ramsperger-Kassel-Marcus (RRKM) calculations agree satisfactorily with experimental observations. According to our calculations, the singlet channel involving formation of SSCO followed by direct dissociation into S2(a 1Deltag)+CO dominates below 2000 K; SSCO is formed via intersystem crossing from the triplet surface. At low temperature and under high pressure the stabilization of OCS2, formed via isomerization of SSCO, becomes important; its formation and further reaction with S atoms partially account for the observed increase in the rate coefficient under such conditions.

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Section: A Experimental Rate Coefficient Below 250 Torrsupporting

confidence: 90%

Section: A Experimental Rate Coefficient Below 250 Torrmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

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Experimental and theoretical investigation of rate coefficients of the reaction S(P3)+OCS in the temperature range of 298–985K

Lee

et al. 2006

The Journal of Chemical Physics

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“…The curvature of the calibration curve was determined assuming the single-exponential decay of S atom concentrations by the pressure-independent reference reaction, 3,8 The obtained calibration curve for the high-pressure range is shown in Figure 1, where those at lower pressure range used in the previous study are shown for comparison. The curvature of the calibration curve was determined assuming the single-exponential decay of S atom concentrations by the pressure-independent reference reaction, 3,8 The obtained calibration curve for the high-pressure range is shown in Figure 1, where those at lower pressure range used in the previous study are shown for comparison.…”

Section: Methodsmentioning

confidence: 99%

Investigation on the Insertion Channel in the S(³P) + H₂ Reaction

1998

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To reexamine the possibility of the spin-forbidden, molecular-elimination mechanism of the thermal decomposition of H 2 S, H 2 S + M f S( 3 P) + H 2 + M (1), recently indicated by experimental and theoretical studies, as well as to examine the cause of discrepancies of its rate constants among recent works, the reverse insertion channel of the S( 3 P) + H 2 reaction, S( 3 P) + H 2 + M f H 2 S + M (-1), has been investigated. The experiments have been conducted with an excimer-laser photolysis (248 nm) in a shock tube at a lower temperature range, 900-1050 K, and a higher pressure range up to 4 atm, than previous studies, where the insertion process (-1) was estimated to be dominant over the simple hydrogen-atom-transfer reaction, S( 3 P) + H 2 f H + HS (2). The decay rate of S( 3 P) atoms has been measured by using an atomic resonance absorption spectrometry technique. The measured rate constant agreed well with the extrapolation of the previous measurements for reaction 2, showing that the recombination channel (-1) is still minor at these experimental conditions. The upper limit of the rate constant for reaction 1 derived in the present study was shown to be consistent with the theoretical rate constant calculated by the Troe's formula with the ab initio threshold energy for the intersystem crossing and with reasonable weak collision factors derived from the rate constant for reaction 1 reported by Shiina et al. [J.

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“…Time evolutions of S and O atoms measured under the same experimental condition are shown in Figure 4. S atoms produced in the photolysis showed single exponential decay and the net rate for the reaction S ϩ O 2 was determined by subtracting the contribution of the reaction S ϩ COS (typically 4 -18% of the whole rate) [8,30]. O atoms increase initially via the reaction (2) but then decrease caused by the reaction, O ϩ COS : CO ϩ SO.…”

Section: Reaction Of S(mentioning

confidence: 99%

Studies on the oxidation mechanism of H2S based on direct examination of the key reactions

Tsuchiya

Kamiya

Matsui

1997

Int. J. Chem. Kinet.

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numbers of studies were performed until very recently on the fundamental oxidation reaction mechanism of hydrogen sulfide and related H 9 S 9 O reaction systems.The oxidation process of H 2 S (and some times the catalytic effect of SO 2 ) have been investigated in several flame studies [1 -5], and the reaction mechanisms were discussed based on the measured product distributions. These studies have provided much useful information on the elementary reactions of H 9 S 9 O systems, however, it is generally very difficult to judge the reliability of kinetic/thermodynamic parameters of individual elementary reactions proposed in these indirect studies. It is also noted that even a conventional shock tube study was not performed for clarifying oxidation mechanism of H 2 S (as far as we know), except an ignition delay mea- INTRODUCTIONThe oxidation of hydrogen sulfide in combustion of fossil fuels and the consecutive atmospheric processes of sulfur oxides are creating serious pollution problems on a global scale.Many practical studies for reducing SO x in combustion systems have been conducted from the engineering point of view. In contrast, only very limited (1), the rate constants evaluated by numerical simulations are summarized as; k 1 ϭ 3.1 ϫ 10 Ϫ11 exp[Ϫ 75 kJ mol Ϫ1 /RT ] cm 3 molecule Ϫ1 s Ϫ1 (T ϭ 1400 -1850 K) with an uncertainty factor of about 2. Direct measurements of the rate constants for S ϩ O2 : SO ϩ O (2), and SO ϩ O 2 : SO 2 ϩ O (3) yield k 2 ϭ (2.5 Ϯ 0.6) ϫ 10 Ϫ11 exp[Ϫ(15.3 Ϯ 2.5) kJ mol Ϫ1 /RT ] cm 3 molecule Ϫ1 s Ϫ1 (T ϭ 980 -1610 K) and, k 3 ϭ (1.7 Ϯ 0.9) ϫ 10 Ϫ12 exp[Ϫ(34 Ϯ 11) kJ mol Ϫ1 /RT ] cm 3 molecule Ϫ1 s Ϫ1 (T ϭ 1130 -1640 K), respectively. By summarizing these data together with the recent experimental results on the H 9 S 9 O reaction systems, a new kinetic model for the H 2 S oxidation process is constructed. It is found that this simple reaction scheme is consistent with the experimental result on the induction time of SO 2 formation obtained by Bradley and Dobson.

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Thermal Decomposition of COS

Cited by 29 publications

References 6 publications

Experimental and theoretical investigation of rate coefficients of the reaction S(P3)+OCS in the temperature range of 298–985K

Experimental and theoretical investigation of rate coefficients of the reaction S(P3)+OCS in the temperature range of 298–985K

Investigation on the Insertion Channel in the S(³P) + H₂ Reaction

Studies on the oxidation mechanism of H2S based on direct examination of the key reactions

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Thermal Decomposition of COS

Cited by 29 publications

References 6 publications

Experimental and theoretical investigation of rate coefficients of the reaction S(P3)+OCS in the temperature range of 298–985K

Experimental and theoretical investigation of rate coefficients of the reaction S(P3)+OCS in the temperature range of 298–985K

Investigation on the Insertion Channel in the S(3P) + H2 Reaction

Studies on the oxidation mechanism of H2S based on direct examination of the key reactions

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Product

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Investigation on the Insertion Channel in the S(³P) + H₂ Reaction