Selectivity-determining steps for ethylene hydroformylation, i.e., ethyl hydrogenation versus CO insertion on Rh(111) and Rh@Cu(111) surfaces were investigated by density functional theory calculations. Compared with the Rh(111) surface, the Rh@Cu(111) surface decreases the hydrogenation barrier by 0.12 eV and more significantly the CO insertion barrier by 0.78 eV due to the ensemble and ligand effects. This result indicates that Rh@Cu(111) alloy catalyst can improve the selectivity of the hydroformylation.%采用密度泛函理论对比研究了Rh(111)表面与Rh@Cu(111)表面合金上乙基加氢反应及CO插入反应过程.结果发现,与Rh(111)表面相比,Rh@Cu(111)表面合金的集团效应和配体效应使得加氢反应的能垒降低了0.12 eV,而CO插入反应的却显著降低了0.78 eV.这表明RhCu合金催化剂可以有效地提高氢甲酰化反应的选择性.
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