Bifunctional hydroformylation on heterogeneous Rh-WOx pair site catalysts
Bifunctional hydroformylation on heterogeneous Rh-WOx pair site catalysts
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DOI：
10.1038/s41586-022-05075-4
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发表时间：
2022-09-08
期刊：
影响因子：
64.8
通讯作者：
Christopher, Phillip
中科院分区：
文献类型：
--
作者：
Ro, Insoo;Qi, Ji;Christopher, Phillip
金属催化的反应通常被假设为在双功能活性位点上进行，由此共定位的反应性物种促进催化循环中的不同基本步骤（1-8）。在均相双核有机金属催化剂上已经建立了双功能活性中心（9-11）。存在负载型金属催化剂上的双功能活性位点的经验证据，例如，在金属氧化物载体界面（2，6，7，12）。然而，由于潜在的活性中心结构的分布、它们的动态重构和所需的非平均场动力学描述，阐明负载型金属催化剂上的双功能反应机制是具有挑战性的（7，12，13）。我们克服了这些限制，通过合成支撑的，原子分散的铑-钨氧化物（Rh-WOx）对网站催化剂。相对简单的对网站的结构和充分的描述，通过平均场建模，使相关的实验动力学与基于第一原理的微观动力学模拟。Rh-WOx对位点通过双功能机制催化乙烯加氢，包括Rh辅助的WO（x）还原、乙烯从WOx转移到Rh和Rh-WOx界面处的H-2解离。在气相乙烯加氢反应中，当产物生成速率为0.1g（丙醛）CM ~（-3）h ~（-1）时，对中心的选择性大于95%。我们的研究结果表明，氧化物负载的对位点可以使双功能反应机制具有高活性和选择性的反应，在工业上使用均相催化剂进行。
Metal-catalysed reactions are often hypothesized to proceed on bifunctional active sites, whereby colocalized reactive species facilitate distinct elementary steps in a catalytic cycle(1-8). Bifunctional active sites have been established on homogeneous binuclear organometallic catalysts(9-11). Empirical evidence exists for bifunctional active sites on supported metal catalysts, for example, at metal-oxide support interfaces(2,6,7,12) . However, elucidating bifunctional reaction mechanisms on supported metal catalysts is challenging due to the distribution of potential active-site structures, their dynamic reconstruction and required non-mean-field kinetic descriptions(7,12,13) . We overcome these limitations by synthesizing supported, atomically dispersed rhodium-tungsten oxide (Rh-WOx) pair site catalysts. The relative simplicity of the pair site structure and sufficient description by mean-field modelling enable correlation of the experimental kinetics with first principles-based microkinetic simulations. The Rh-WOx pair sites catalyse ethylene hydroformylation through a bifunctional mechanism involving Rh-assisted WO(x )reduction, transfer of ethylene from WOx to Rh and H-2 dissociation at the Rh-WOx interface. The pair sites exhibited >95% selectivity at a product formation rate of 0.1g(propanal) CM-3 h(-l) in gas-phase ethylene hydroformylation. Our results demonstrate that oxide-supported pair sites can enable bifunctional reaction mechanisms with high activity and selectivity for reactionsthat are performed in industry using homogeneous catalysts.