Transformations of Ethylene on the Pd(111) Surface: A Density Functional Study
Transformations of Ethylene on the Pd(111) Surface: A Density Functional Study
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DOI：
10.1021/jp104949w
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发表时间：
2010-10-21
影响因子：
3.7
通讯作者：
Roesch, Notker
中科院分区：
文献类型：
--
作者：
Chen, Zhao-Xu;Aleksandrov, Hristiyan A.;Roesch, Notker
乙烯在VIII族金属上的化学性质对于石化和聚合物工业是重要的。到目前为止，一个完整的基于第一性原理的转化网络的乙烯作为一个原型烯烃系统在金属表面上是缺乏的。本文基于密度泛函平板模型计算，对乙烯在Pd（111）表面的转化反应进行了全面的研究。具体而言，我们表征了一系列物种C（2）H（a）（x = 0-4）的C-H和C-C键断裂以及II异构化的热力学和动力学。因此，脱氢或氢化过程对大多数物种有利，而涉及C-C键断裂或形成的反应具有高势垒。乙炔基（CHC）可能是C-C键断裂的前体。乙撑基被发现位于盆地或势能面，这使得人们能够合理化相关的实验观察。此外，我们注意到，在使用单位键指数二次指数势（UBI-QEP）方法获得的势能面信息时应谨慎。
The chemistry of ethylene on group VIII metals is important for the petrochemical and polymer industries. Thus far, a complete first-principles-based conversion network of ethylene as a prototypical olefin system on metal surfaces is lacking. In this paper we present a comprehensive view on transformations of ethylene on Pd(111), based on density functional slab model calculations. Specifically, we characterized the thermodynamics and kinetics of C-H and C-C bond scission as well as II isomerization of a series of species C(2)H(a) (x = 0-4). Accordingly, dehydrogenation or hydrogenation processes are favored for most species, whereas reactions involving the scission or formation of the C-C bond feature high barriers. Ethynyl (CHC) likely is the precursor of C-C bond scission. Ethylidyne is found to be located in a basin or the potential energy surface, which allows one to rationalize relevant experimental observations. In addition, we note that one should be cautious when using information on the potential energy surface obtained with the unity-bond-index quadratic-exponential-potential (UBI-QEP) method.