Sweeny Brendan C, Ard Shaun G, Shuman Nicholas S, Viggiano Albert A
National Academy of Sciences, Washington, DC 20001.
Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico, 87117.
Chemphyschem. 2018 Nov 5;19(21):2835-2838. doi: 10.1002/cphc.201800714. Epub 2018 Sep 19.
The mechanisms involved in catalytic oxidation of CO by N O promoted by the AlVO and AlVO ions are evaluated using temperature-dependent rate constants and statistical modeling. Reactions were studied from 300-600 K using a selected ion flow tube (SIFT) apparatus, and the data compared to statistical modeling of proposed mechanisms previously identified by density functional theory (DFT) calculations. Reduction of N O by AlVO was found to take place only by complexation to the Al site; however, attack on the V site also occurred and led to stable association complexes, reducing the overall efficiency of the reaction. As the AlVO (N O) complex resulted from approach on the V site, it did not block the reactive Al site and was observed to further react with N O to form AlVO (N O). The oxidation of CO by AlVO was found to proceed solely by activation on the Al-O site; however, isomerization of complexes formed with CO initially complexed to the V site were found to add to the reactivity, especially at lower temperatures.
利用与温度相关的速率常数和统计模型，评估了由AlVO和AlVO离子促进的NO对CO的催化氧化所涉及的机制。使用选定离子流管（SIFT）装置在300 - 600 K温度范围内研究反应，并将数据与先前通过密度泛函理论（DFT）计算确定的反应机制的统计模型进行比较。发现AlVO对NO的还原仅通过与Al位点络合发生；然而，对V位点的攻击也会发生，并导致形成稳定的缔合络合物，从而降低反应的整体效率。由于AlVO(NO)络合物是由在V位点上的接近形成的，它不会阻塞活性Al位点，并且观察到它会进一步与NO反应形成AlVO(NO)。发现AlVO对CO的氧化仅通过在Al - O位点上的活化进行；然而，最初与V位点络合的CO形成络合物的异构化被发现会增加反应活性，特别是在较低温度下。
