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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Temperature and Isotope Dependent Kinetics of Nickel-Catalyzed Oxidation of Methane by Ozone
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Temperature and Isotope Dependent Kinetics of Nickel-Catalyzed Oxidation of Methane by Ozone

机译：臭氧含镍催化氧化氧化氧化的温度和同位素依赖性动力学

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摘要

The temperature dependent kinetics of Ni+ + O-3 and of NiO+ + CH4/CD4 are measured from 300 to 600 K using a selected-ion flow tube apparatus. Together, these reactions comprise a catalytic cycle converting CH4 to CH3OH. The reaction of Ni+ + O-3 proceeds at the collisional limit, faster than previously reported at 300 K. The NiO+ product reacts further with O-3, also at the collisional limit, yielding both higher oxides (up to NiO5+ is observed) as well as undergoing an apparent reduction back to Nit. This apparent reduction channel is due to the oxidation channel yielding NiO2+* with sufficient energy to dissociate. (NiO+)-Ni-4 + CH4 (CD4) (whereas (NiO+)-Ni-4 refers to the quartet state of NiO+) proceeds with a rate constant of (2.6 +/- 0.4) X 10(-10) cm(3) s(-1) [(1.8 +/- 0.5) x 10(-10) cm(3) s(-1)] at 300 K and a temperature dependence of similar to T-0.7 +/- 0.3 (similar to T-1.1 +/- 0.4) producing only the Ni-2(+) + (CH3OH)-C-1 channel up to 600 K. Statistical modeling of the reaction based on calculated stationary points along the reaction coordinate reproduces the experimental rate constant as a function of temperature but underpredicts the kinetic isotope shift. The modeling was found to better represent the data when the crossing from quartet to doublet surface was incomplete, suggesting a possible kinetic effect in crossing from quartet to doublet surfaces. Additionally, the modeling predicts a competing (NiOH+)-Ni-3 + (CH3)-C-2 channel to become increasingly important at higher temperatures.
机译：Ni的温度依赖性动力学+ + O-3的NiO + + CH4 / CD4的和从300到600说明使用选择的离子流动管装置进行测定。总之，这些反应包括催化循环转换到CH4 CH3OH。 Ni的反应+ + O-3进行的碰撞的限制，比以前在300个与O-3，也是在碰撞极限，产生既有较高的氧化物（高达NiO5 +观察）K.所述的NiO +产物进一步反应所报告更快及正进行的表观减少回尼特。这种明显减少信道是由于氧化通道产生NIO2 + *足够的能量而解离。 （的NiO +） - 镍4 + CH 4（CD4）（然而（的NiO +） - 镍4指的NiO +的四状态）的（2.6±0.4）×10（-10）厘米（速率常数进行3）S（-1）[（1.8 +/- 0.5）×10（-10）厘米（3）S（-1）]在300°K和的类似的温度依赖性T-0.7 +/- 0.3（类似于到T-1.1±0.4）仅产生的Ni-2（+）+（CH 3 OH）-C-1通道到基于沿着反应计算驻点反应600 K.统计建模坐标再现实验速率常数作为温度的函数，但underpredicts动力学同位素位移。建模发现，以更好地表示当从四方交叉到双峰表面是不完整的，这表明在交叉处的可能的动力学效应从四方到双峰表面的数据。此外，建模预测竞争（化NiOH +） - 镍-3 +（CH 3）-C-2信道，成为在较高的温度越来越重要。

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