Wang Shengkai, Dames Enoch E, Davidson David F, Hanson Ronald K
High Temperature Gasdynamics Lab, Mechanical Engineering, Stanford University , Stanford, California 94305 United States.
J Phys Chem A. 2014 Nov 6;118(44):10201-9. doi: 10.1021/jp5085795. Epub 2014 Oct 23.
The rate constant of the H-abstraction reaction of formaldehyde (CH2O) by hydrogen atoms (H), CH2O + H = H2 + HCO, has been studied behind reflected shock waves with use of a sensitive mid-IR laser absorption diagnostic for CO, over temperatures of 1304-2006 K and at pressures near 1 atm. C2H5I was used as an H atom precursor and 1,3,5-trioxane as the CH2O precursor, to generate a well-controlled CH2O/H reacting system. By designing the experiments to maintain relatively constant H atom concentrations, the current study significantly boosted the measurement sensitivity of the target reaction and suppressed the influence of interfering reactions. The measured CH2O + H rate constant can be expressed in modified Arrhenius from as kCH2O+H(1304-2006 K, 1 atm) = 1.97 × 10(11)(T/K)(1.06) exp(-3818 K/T) cm(3) mol(-1)s(-1), with uncertainty limits estimated to be +18%/-26%. A transition-state-theory (TST) calculation, using the CCSD(T)-F12/VTZ-F12 level of theory, is in good agreement with the shock tube measurement and extended the temperature range of the current study to 200-3000 K, over which a modified Arrhenius fit of the rate constant can be expressed as kCH2O+H(200-3000 K) = 5.86 × 10(3)(T/K)(3.13) exp(-762 K/T) cm(3) mol(-1)s(-1).
利用对一氧化碳的灵敏中红外激光吸收诊断技术，在反射激波后研究了氢原子（H）与甲醛（CH₂O）的氢提取反应CH₂O + H = H₂ + HCO的速率常数，实验温度范围为1304 - 2006K，压力接近1个大气压。使用碘乙烷（C₂H₅I）作为氢原子前驱体，1,3,5 - 三氧杂环己烷作为甲醛前驱体，以生成一个可控的CH₂O/H反应体系。通过设计实验保持氢原子浓度相对恒定，本研究显著提高了目标反应的测量灵敏度，并抑制了干扰反应的影响。测得的CH₂O + H速率常数可以用修正的阿仑尼乌斯公式表示为kCH₂O + H(1304 - 2006K, 1 atm) = 1.97 × 10¹¹(T/K)¹·⁰⁶ exp(-3818K/T) cm³ mol⁻¹ s⁻¹，估计不确定度范围为+18%/-26%。采用CCSD(T)-F12/VTZ - F12理论水平的过渡态理论（TST）计算结果与激波管测量结果吻合良好，并将本研究的温度范围扩展到200 - 3000K，在此温度范围内速率常数的修正阿仑尼乌斯拟合公式可表示为kCH₂O + H(200 - 3000K) = 5.86 × 10³(T/K)³·¹³ exp(-762K/T) cm³ mol⁻¹ s⁻¹。
