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Reagent-Triggered Isomerization of Fluxional Cluster Catalyst via Dynamic Coupling
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2020-03-30 , DOI: 10.1021/acs.jpclett.0c00548
Han Guo , Philippe Sautet 1 , Anastassia N. Alexandrova 1
Affiliation  

Metallic cluster catalysts have many thermodynamically accessible isomers with diverse active sites and low reaction barriers, and lately a strong hypothesis emerged that the many catalyst states collectively drive the catalysis. However, it remained a hypothesis that catalyst isomerization is actually kinetically feasible under the current reaction conditions. Using high-temperature dynamics simulations and sampling, a range of orientations, and vibrational energy distributions, we probe how thermal effects and molecular events affect cluster catalyst dynamics. We show that even such a delicate affair as the dissociation or scattering of a methane molecule on the heavy and thus slow Pt13 cluster triggers substantial isomerization of the catalyst, far beyond thermal at 700 K. A kinetic coupling between the methane activity and cluster catalyst dynamics is observed. In return, the thermal dynamics of the cluster affects the methane reaction and scattering probabilities. Hence, molecular events at the surfaces of fluxional cluster catalysts should facilitate the population of an ensemble of catalyst states under the current reaction conditions, with implications for available active sites, reaction mechanisms, and apparent rates.

中文翻译:

动态耦合的簇簇催化剂引发试剂的异构化

金属簇催化剂具有许多热力学上可及的异构体,这些异构体具有不同的活性位点和低的反应势垒,最近出现了一个强有力的假设,认为许多催化剂状态共同驱动了催化作用。然而,仍然存在这样的假设:在当前反应条件下,催化剂异构化实际上在动力学上是可行的。使用高温动力学模拟和采样,一系列方向和振动能分布,我们探究了热效应和分子事件如何影响簇状催化剂动力学。我们表明,即使是如此微妙的事情,例如甲烷分子在重且缓慢的Pt 13上的解离或散射团簇触发了催化剂的大量异构化,远远超过了700 K时的热。观察到了甲烷活性和团簇催化剂动力学之间的动力学耦合。作为回报,团簇的热动力学影响甲烷反应和散射概率。因此,在当前反应条件下,助熔簇状催化剂表面的分子事件应促进整体催化剂状态的聚集,并影响可用的活性位点,反应机理和表观速率。
更新日期:2020-04-24
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