High‐temperature kinetics of the reactions of SO 2 and SO 3 with atomic oxygen

A nozzle‐beam‐skimmer sampling system is used to measure species concentration profiles for a lean one‐dimensional premixed COO 2 Ar flame, into which small amounts of sulfur dioxide are introduced. The net formation rate for sulfur trioxide is obtained from the flux fraction profile for this species. The kinetic schemeis then utilized, along with the measured temperature profiles, to evaluate the rate coefficients k 1 and k 2 over the temperature range of 1435–1850 K. The most satisfactory agreement between the measured net formation rate for SO 3 and that calculated on the basis of reactions (1) and (2) is obtained with the rate coefficients\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = 4.4 \times 10^{14} \exp [3163/T]{\rm cm}^{\rm 6} {\rm /mol}^{\rm 2} \cdot {\rm s}$$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$k_2 = 1.32 \times 10^{12} \exp [- 3070/T]{\rm cm}^{\rm 3} {\rm /mol} \cdot {\rm s}$$\end{document}Reactions (1) and (2) are found to be nearly balanced in a substantial region of the flame. Here the data are more sensitive to the difference in activation energies, as opposed to a particular value for either. Implications of this observation on the uncertainty of the deduced temperature dependence for each reaction are discussed, as are some of the procedures used in the data analysis.