The Crucial Role of Cluster Morphology on the Epoxidation of Propene Catalyzed by Cu₅: A DFT Study

The selective oxidation of propene to propene oxide (PO) is an industrially relevant and still challenging reaction that requires the design of highly specific catalysts able to improve simultaneously activity and selectivity. Metallic copper exhibits high selectivity toward propene epoxidation that drops when the catalyst surface is oxidized under reaction conditions. On the basis of previous work showing that small planar Cu5 clusters are more resistant to oxidation than 3D ones, we have performed a detailed theoretical study of the mechanism of propene oxidation with molecular O2 and atomic O adsorbed on both planar and 3D Cu5 clusters. The desired pathways leading to PO as well as the undesired routes producing propanal, acetone, or allyl intermediates that finally evolve to acrolein or CO2 have been considered, and the global analysis of all data indicates that planar Cu5 clusters are promising candidates for the selective epoxidation of propene.