Abstract: 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.

Key words: hydroformylation, rhodium, copper, alloy, density functional theory