The development of new bimetallic catalysts for selective transformation of highly functionalized biomass derivatives has become an important area of research. The chemical activities of bimetallic vapor-deposited Pt-Sn clusters supported on TiO<sub>2</sub>(110) surfaces are investigated as model systems for understanding Pt-Sn catalysts for selective hydrogenation reactions. The sizes and size distributions of monometallic and bimetallic clusters are studied by scanning tunneling microscopy. In addition, the surface compositions of Pt-Sn bimetallic surfaces are characterized by low energy ion scattering (LEIS) and grazing angle X-ray photoelectron spectroscopy (XPS) studies, and the number of actives sites is probed by temperature programmed desorption (TPD) experiments with CO. XPS experiments provide valuable insight into oxidation states and bimetallic interactions in Pt-Sn particles. For bimetallic clusters prepared by depositing Sn on Pt, the lower surface free energy of Sn results in Sn-rich surfaces with Pt in the core of the clusters. For Pt deposited on Sn clusters, both Sn and Pt coexist at the surface. The activities of these model surfaces for selective hydrogenation of unsaturated aldehydes are studied in a microreactor coupled to an ultrahigh vacuum chamber, where the surfaces can be characterized by XPS before and after reaction. Density functional theory calculations are carried out to understand the interactions of the clusters with the support and the reaction mechanisms for selective hydrogenation.

Growth and activity studies of titania-supported Pt-Sn model catalysts for selective hydrogenation reactions

2019 Spring National Meeting

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