Ethylene Conversion to Ethylidyne over Pd(111): Revisiting the Mechanism with First-Principles Calculations
Ethylene Conversion to Ethylidyne over Pd(111): Revisiting the Mechanism with First-Principles Calculations
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DOI：
10.1021/jp8082562
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发表时间：
2009-01
影响因子：
3.7
通讯作者：
L. Moskaleva;Zhao‐Xu Chen;H. Aleksandrov;Amjad Basha Mohammed;Qiao Sun;N. Rösch
中科院分区：
文献类型：
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作者：
L. Moskaleva;Zhao‐Xu Chen;H. Aleksandrov;Amjad Basha Mohammed;Qiao Sun;N. Rösch
在Pd（111）上，乙烯的热活化得到了乙炔。利用更近似的模型，最近在DFT计算的基础上提出了乙烯→乙烯基→乙炔→乙炔的三步反应机理。我们采用了更精细的计算模型，并表征了乙烯在Pd上转化为乙炔的热力学和动力学机制（111）。我们对三种覆盖度的吸附质，1/3、1/4和1/9进行了密度功能板模型研究。最终得到的精细化势能图与之前报道的结果明显不同：我们计算的各个基本步骤的障碍明显低于之前的研究，我们确定整个过程是放热的，与之前的计算结果相反。结果表明，该三步反应机理在Pd（111）上是热力学和动力学上可行的，乙烯脱氢制乙烯的速率为1%。
On Pd(111), thermal activation of ethylene has been reported to yield ethylidyne. Using more approximate models, a plausible three-step mechanism, ethylene → vinyl → ethylidene → ethylidyne, was recently proposed for this process on the basis of DFT calculations. We employed more elaborate computational models and characterized the thermodynamics and kinetics of the mechanism of ethylene conversion to ethylidyne on Pd(111). We carried out density functional slab-model studies for three coverages of the adsorbate, 1/3, 1/4, and 1/9. The resulting refined potential energy landscape turned out to differ notably from that reported previously: our calculated barriers for the various elementary steps are significantly lower than those of previous studies, and we determined the overall process to be exothermic, in contrast to earlier computational results. We show that the three-step mechanism is thermodynamically and kinetically feasible on Pd(111), with the dehydrogenation of ethylene to vinyl being the rate-l...