Yilmaz Ayten, Hindiyarti Lusi, Jensen Anker D, Glarborg Peter, Marshall Paul
Department of Chemical Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark.
J Phys Chem A. 2006 Jun 1;110(21):6654-9. doi: 10.1021/jp0557215.
The thermal dissociation of SO3 has been studied for the first time in the 1000-1400 K range. The experiments were conducted in a laminar flow reactor at atmospheric pressure, with nitrogen as the bath gas. On the basis of the flow reactor data, a rate constant for SO3 + N2 --> SO2 + O + N2 (R1b) of 5.7 x 10(17) exp(-40000/T) cm3/(mol s) is derived for the temperature range 1273-1348 K. The estimated uncertainty is a factor of 2. The rate constant corresponds to a value of the reverse reaction of k1 approximately 1.8 x 10(15) cm6 mol(-2) s(-1). The reaction is in the fall-off region under the investigated conditions. The temperature and pressure dependence of SO2 + O (+N2) was estimated from the extrapolation of low temperature results for the reaction, together with an estimated broadening parameter and the high-pressure limit determined recently by Naidoo, Goumri, and Marshall (Proc. Combust. Inst. 2005, 30, 1219-1225). The theoretical rate constant is in good agreement with the experimental results. The improved accuracy in k(1) allows a reassessment of the rate constant for SO3 + O --> SO2 + O2 (R2) based on the data of Smith, Tseregounis, and Wang (Int. J. Chem. Kinet. 1982, 14, 679-697), who conducted experiments on a low-pressure CO/O2/Ar flame doped with SO2. At the location in the flame where the net SO3 formation rate is zero, k2 = k1[SO2][M]/[SO3]. A value of 6.9 x 10(10) cm3 mol(-1) s(-1) is obtained for k2 at 1269 K with an uncertainty a factor of 3. A recommended rate constant k2 = 7.8 x 10(11) exp(-3065/T) cm3 mol(-1) s(-1) is consistent with other flame results as well as the present flow reactor data.
首次在1000 - 1400K温度范围内研究了SO₃的热分解。实验在常压下的层流反应器中进行，以氮气作为缓冲气体。基于流动反应器的数据，在1273 - 1348K温度范围内，推导出SO₃ + N₂ → SO₂ + O + N₂（R1b）的速率常数为5.7×10¹⁷ exp(-40000/T) cm³/(mol s)。估计的不确定度为2倍。该速率常数对应于逆反应k1的值约为1.8×10¹⁵ cm⁶ mol⁻² s⁻¹。在所研究的条件下，该反应处于过渡区。SO₂ + O（+N₂）的温度和压力依赖性是根据该反应低温结果的外推，结合一个估计的展宽参数以及Naidoo、Goumri和Marshall最近确定的高压极限（《燃烧学会会刊》2005年，30卷，1219 - 1225页）估算出来的。理论速率常数与实验结果吻合良好。k(1)精度的提高使得能够基于Smith、Tseregounis和Wang（《国际化学动力学杂志》1982年，14卷，679 - 697页）的数据重新评估SO₃ + O → SO₂ + O₂（R2）的速率常数，他们在掺杂了SO₂的低压CO/O₂/Ar火焰中进行了实验。在火焰中净SO₃生成速率为零的位置，k2 = k1[SO₂][M]/[SO₃]。在1269K时，k2的值为6.9×10¹⁰ cm³ mol⁻¹ s⁻¹，不确定度为3倍。推荐的速率常数k2 = 7.8×10¹¹ exp(-3065/T) cm³ mol⁻¹ s⁻¹与其他火焰结果以及当前的流动反应器数据一致。
