Ethylene conversion to ethylidyne on Pd(111) and Pt(111): A first-principles-based kinetic Monte Carlo study
Ethylene conversion to ethylidyne on Pd(111) and Pt(111): A first-principles-based kinetic Monte Carlo study
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DOI：
10.1016/j.jcat.2011.09.035
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发表时间：
2012-01-01
影响因子：
7.3
通讯作者：
Roesch, Notker
中科院分区：
文献类型：
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作者：
Aleksandrov, Hristiyan A.;Moskaleva, Lyudmila V.;Roesch, Notker
我们提出了动力学Monte Carlo模拟乙烯转化为乙炔在Pd（1 1 1）和Pt（1 1 1）表面上，从周期性密度泛函计算得到的反应barrier和的基础上。我们考虑了三种可能的机制，包括四种不同的中间体，乙基，乙烯基，亚乙基，和亚乙烯基。我们的模拟预测，在两个表面上最合理的途径是乙烯->乙烯基->亚乙烯基->乙炔。与先前关于脱氢成乙烯基在Pt（111）上是限速的建议相反，我们发现亚乙烯基到乙炔的氢化在该表面上是至关重要的。在Pd（111）上，乙烯的初始脱氢是限速的。因此，亚乙烯基物质积累在Pt（111）上，而Pd（111）上的所有中间体快速转化为次乙基而没有积累。在Pd（111）和Pt（111）上生成次乙基的模拟表观活化能分别为94 kJ mol（-1）和65 kJ mol（-1），与实验结果吻合较好. (C)2011 Elsevier Inc. All rights reserved.
We present kinetic Monte Carlo simulations of ethylene conversion to ethylidyne on Pd(1 1 1) and Pt(1 1 1) surfaces, on the basis of reaction enthalpies and barriers obtained from periodic density functional calculations. We considered three possible mechanisms encompassing four different intermediates, ethyl, vinyl, ethylidene, and vinylidene. Our simulations predict that the most plausible pathway on both surfaces is ethylene --> vinyl --> vinylidene --> ethylidyne. In contrast to earlier suggestions that the dehydrogenation to vinyl is rate-limiting on Pt(1 1 1), we found the hydrogenation of vinylidene to ethylidyne to be crucial on this surface. On Pd(1 1 1), the initial dehydrogenation of ethylene is rate-limiting. Hence, vinylidene species accumulate on Pt(1 1 1), while all intermediates on Pd(1 1 1) convert rapidly to ethylidyne without accumulation. The simulated apparent activation energies for the formation of ethylidyne on Pd(1 11 ), 94 kJ mol(-1), and on Pt(1 1 1), 65 kJ mol(-1), agree well with experimental results. (C) 2011 Elsevier Inc. All rights reserved.