High-temperature kinetics of the reactions of SO2 and SO3 with atomic oxygen

A nozzle-beam-skimmer sampling system is used to measure species concentration profiles for a lean one-dimensional premixed CO? O₂? 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 scheme is then utilized, along with the measured temperature profiles, to evaluate the rate coefficients k₁ and k₂ over the temperature range of 1435–1850 K. The most satisfactory agreement between the measured net formation rate for SO₃ and that calculated on the basis of reactions (1) and (2) is obtained with the rate coefficients 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.