Determination of the rate coefficients of the SO2 + O + M → SO3 + M reaction

✍ Scribed by S. M. Hwang; J. A. Cooke; K. J. De Witt; M. J. Rabinowitz

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 360 KB
• Volume: 42
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20472

✦ Synopsis

Rate coefficients of the title reaction R 31 (SO 2 + O + M → SO 3 + M) and R 56 (SO 2 + HO 2 → SO 3 + OH), important in the conversion of S(IV) to S(VI), were obtained at T = 970-1150 K and ρ ave = 16.2 μmol cm -3 behind reflected shock waves by a perturbation method. Shockheated H 2 /O 2 /Ar mixtures were perturbed by adding small amounts of SO 2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k 31 and k 56 values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R 56 ). In the experimental conditions of this study, R 31 is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k 31,0 /[Ar] = 2.9 × 10 35 T -6.0 exp(-4780 K/T ) + 6.1 × 10 24 T -3.0 exp(-1980 K/T ) cm 6 mol -2 s -1 at T = 300-2500 K; k 56 = 1.36 × 10 11 exp(-3420 K/T ) cm 3 mol -1 s -1 at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k 31,0 and k 56 expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at