Heterogeneous reaction mechanisms of the reduction of nitric oxide on carbon surfaces: a theoretical analysis
Heterogeneous reaction mechanisms of the reduction of nitric oxide on carbon surfaces: a theoretical analysis
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DOI：
10.1007/s00214-009-0708-8
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发表时间：
2010-09
影响因子：
1.7
通讯作者：
A. Arenillas;B. Arias;F. Rubiera;J. J. Pis-J.;R. López;P. Campomanes;C. Pevida;M. I. Menéndez
中科院分区：
文献类型：
--
作者：
A. Arenillas;B. Arias;F. Rubiera;J. J. Pis-J.;R. López;P. Campomanes;C. Pevida;M. I. Menéndez
在UB 3LYP/6-31 + G（d）和UM 06 -2X水平上研究了NO与两种含活性中心的碳材料模型的反应机理。小的模型是蒽自由基，大的模型也是由十个苯环构成的单价自由基。发现与这两个模型的机制路线导致一个令人满意的理由的实验数据，并显示了重要的作用的温度和氧和氮的表面络合物，在碳质材料中产生的中间步骤的机制，在全球的过程。在这项工作中提出的计算结果表明，在低温下，高吉布斯能垒后出现的N2释放从（NO）2二聚体，最初化学吸附在焦炭表面上，防止随后的演变的系统，结果，CO2排放不发生。另一方面，在高温下，反应物可用的平均能量可能足以克服这一能量势垒，从而导致N2和CO2作为还原产物的形成。N2可能来自两个来源，这取决于NO分子在反应坐标的不同点处的接近。通过一个更大的模型的碳质表面的最佳描述证实了在碳表面上的一氧化氮的还原中N2 O释放的情况。
The mechanism of reaction between NO and two models of carbonaceous materials with active sites was investigated at the UB3LYP/6-31 + G(d) and UM06-2X theory levels. The small model is the anthracene radical and the large one is also a monoradical built with ten benzene rings. The mechanistic routes found with both models lead to a satisfactory justification of the experimental data and showed the important role of the temperature and the oxygen and nitrogen surface complexes, generated in the carbonaceous material at intermediate steps of the mechanism, in the global process. The computational results presented in this work revealed that, at low temperatures, the high Gibbs energy barrier that appears after N2release from the (NO)2dimer, initially chemisorbed on the char surface, prevents the subsequent evolution of the system with the result that CO2emission does not take place. On the other hand, at high temperatures, the mean energy available to the reactants may be sufficient to overcome this energy barrier giving rise to the formation of N2and CO2as reduction products. The N2may come from two sources depending on the approach of the NO molecule at different points of the reaction coordinate. The best description of the carbonaceous surface through a larger model confirms the absence of N2O release in the reduction of nitric oxide on carbon surfaces.