Design of Platinum Based Metallic Catalysts for Selective Hydrogenation of Crotonaldehyde

The physicochemical and catalytic properties of Pt/Ni catalysts for the hydrogenation of crotonaldehyde were investigated. The sites for hydrogenation of the carbon - carbon double bond and the carbon - oxygen double bond were identified. While the rate of C=C bond hydrogenation was sensitive to the nature of the group VIII metal, but insensitive to its environment, the rate of C=O bond hydrogenation increased in parallel to the presence of Pt close to a charged metal atom. For the examples of the present study, the positive charge was localized at the Ni atoms in bimetallic catalysts and at Ti^+x cations of titania suboxide clusters decorating the metal particles for the TiO₂ supported catalysts. The magnitude of the positive charge of the atom close to Pt and the concentration of these ensembles seem to be the most important factors for the enhancement of the rate of C=O bond hydrogenation.