Pt3Ti Intermetallic Alloy Formed by Strong Metal-Support Interaction over Pt/TiO2 for the Selective Hydrogenation of Acetophenone

The strong metal-support interaction over Pt/TiO2 catalysts, which were prepared by depositing size-specified Pt colloids (2-6 nm) onto anatase TiO2 nanosheets dominated by the reactive {001} facets, was featured by the formation of Pt3Ti intermetallic alloy and showed a size-dependent effect. After H-2 reduction at 773 K, bulk Pt-Ti alloys in a mixture of disordered and ordered phases were readily formed over 2 nm Pt particle, while Pt3Ti intermetallic alloys, with a thickness of up to 6 atomic layers, were observed on 4-6 nm Pt particles, showing as a Pt3Ti@Pt core-shell architecture where the Ti atom substituted the Pt atom periodically and interacted with the Pt atom electronically. By further raising the temperature for H-2 reduction to 873 K, the 2-6 nm Pt particles turned into well-crystallized Pt3Ti intermetallic alloys. Both bulk Pt-Ti and Pt3Ti intermetallic alloys suppressed considerably the chemisorption of H-2 and CO but dramatically promoted the selectivity for hydrogenating the C=O bond in acetophenone.