Density-functional theory study of the catalytic oxidation of CO over transition metal surfaces
Density-functional theory study of the catalytic oxidation of CO over transition metal surfaces
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DOI：
10.1016/s0039-6028(99)00531-2
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发表时间：
1999-08-02
期刊：
影响因子：
1.9
通讯作者：
Scheffler, M
中科院分区：
文献类型：
--
作者：
Stampfl, C;Scheffler, M
近年来，由于计算方法的改进和计算机能力的提高，已经可以对表面的“简单”化学反应进行第一原理研究。我们已经进行了这样的研究，CO在过渡金属表面的催化氧化，特别是在钌表面的不寻常的行为相比，其他过渡金属催化剂已被报道。高气压催化反应器实验已经揭示，对于氧化条件，Ru上的反应速率是所考虑的过渡金属中最高的-相比之下，在超高真空条件下，该速率是迄今为止最低的。我们发现，重要的是要了解的压力依赖性的反应，Ru（0001）可以支持高浓度的氧在表面。在这些条件下，O-金属键与较低覆盖率下的O-金属键相比是弱的。我们已经研究了一些可能的反应途径CO氧化的条件下的高氧气覆盖，包括气相CO在氧气覆盖的表面上的散射反应（Eley-Rideal机制），以及Langmuir-Hinshelwood机制涉及吸附的CO分子和O原子之间的反应。(C)1999 Elsevier Science B. V.保留所有权利。
In recent years, due to improvements in calculation methods and increased computer power, it has become possible to perform first-principles investigations for 'simple' chemical reactions at surfaces. We have carried out such studies for the catalytic oxidation of CO at transition metal surfaces, in particular, at the ruthenium surface for which unusual behavior compared to other transition metal catalysts has been reported. High gas pressure catalytic reactor experiments have revealed that the reaction rate over Ru for oxidizing conditions is the highest of the transition metals considered - in contrast, under ultra-high vacuum conditions, the rate is by far the lowest. We find it important for understanding the pressure dependence of the reaction that Ru(0001) can support high concentrations of oxygen at the surface. Under these conditions, the O-metal bond is atypically weak compared to that at lower coverages. We have investigated a number of possible reaction pathways for CO oxidation for the conditions of high oxygen coverage, including scattering reactions of gas-phase CO at the oxygen covered surface (Eley-Rideal mechanism) as well as the Langmuir-Hinshelwood mechanism involving reaction between adsorbed CO molecules and O atoms. (C) 1999 Elsevier Science B.V. All rights reserved.