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Promotion of Inorganic Phosphorus on Rh Catalysts in Styrene Hydroformylation: Geometric and Electronic Effects
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-01-22 , DOI: 10.1021/acscatal.0c04684
Boyang Liu 1 , Ning Huang 1 , Yu Wang 1 , Xiaocheng Lan 1 , Tiefeng Wang 1
Affiliation  

Rh-based homogeneous catalysts with phosphine ligands are highly active in hydroformylation reactions. Using DFT calculations, we found a similar electronic effect of inorganic phosphorus in the Rh2P structure. The energy profiles demonstrated that Rh2P would significantly enhance the styrene hydroformylation activity in comparison with Rh, which was further confirmed by experiments. Triphenylphosphine (PPh3) was used as the phosphorus source, and Rh2P supported on silica was prepared by impregnation at a relatively low temperature (550 °C). The turnover frequency (TOF) of styrene hydroformylation was increased to 1496 h–1, which was comparable with some single atom catalysts (SACs). Recycling tests showed a good stability in five runs. Furthermore, HAADF-STEM, XPS, and other characterizations confirmed the synthesis of the Rh2P structure. The promotion effect of P was bifunctional. On the one hand, the doped P separated the surface Rh atoms, which eliminated the surface hollow sites and prevented excessively strong adsorption of the reactants. On the other hand, electrons transferred from Rh to P, causing the surface Rh atoms to be positively charged, which was favorable for hydroformylation reactions. The geometric effects improved the dispersion and the electronic effects changed the rate-determining step from CO insertion to phenylpropionyl hydrogenation, both leading to a higher hydroformylation activity.

中文翻译:

苯乙烯加氢甲酰化过程中促进Rh催化剂上无机磷的几何和电子效应

具有膦配体的Rh基均相催化剂在加氢甲酰化反应中具有很高的活性。使用DFT计算,我们发现Rh 2 P结构中无机磷具有类似的电子效应。能量分布表明,与Rh相比,Rh 2 P将显着增强苯乙烯加氢甲酰化活性,这已通过实验进一步证实。三苯基膦(PPH 3)用作磷源,和Rh 2 P负载在二氧化硅上以相对低的温度(550℃)的制备是通过浸渍。苯乙烯加氢甲酰化的周转频率(TOF)增加到1496 h –1,与某些单原子催化剂(SAC)相当。回收测试显示五次运行具有良好的稳定性。此外,HAADF-STEM,XPS和其他特征证实了Rh 2 P结构的合成。P的促进作用是双功能的。一方面,掺杂的P分离了表面Rh原子,从而消除了表面中空位并防止了反应物过强的吸附。另一方面,电子从Rh转移到P,使表面Rh原子带正电,这对于加氢甲酰化反应是有利的。几何效应改善了分散性,电子效应改变了决定速率的步骤,从一氧化碳插入到苯丙酰基加氢,均导致更高的加氢甲酰化活性。
更新日期:2021-02-05
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