| AVS 60th International Symposium and Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS+NS-WeM |
| Session: | Nanostructures: Reactivity & Catalysis |
| Presenter: | Y. Li, University of California, Riverside |
| Authors: | Y. Li, University of California, Riverside F. Zaera, University of California, Riverside |
| Correspondent: | Click to Email |
The surface structures of catalysts have in some instances a large impact on their catalytic properties. On the other hand, historically, mild reactions are not considered to be surface structure sensitive. In this work we report on our observation that both the size and the shape of Pt nanoparticles strongly affect the selectivity of glycerol oxidation, a reaction that can proceed at room temperature and under atmospheric pressures. In a series of experiment using Pt/SiO catalysts with average particle sizes varying from 3.9 to 6.2nm, it was determined that selectivity toward primary carbon oxidation increases as the proportion of larger particles increases. Aside from this size effect, supported tetrahedral Pt and cuboctahedral Pt also exhibit different selectivity and kinetic behavior from the regular Pt catalysts.(See Fig. 1&2) We propose that these selectivity differences are due to the different adsorption state of the surface species. Dihydroxyacetone (the product of dehydrogenation on secondary carbon) is thermodynamically more stable than glyceraldehyde (the product of dehydrogenation on primary carbon) but with larger steric hindrance effect in the dehydrogenation process. While on the edge and corner parts of the Pt surface, the steric hindrance could be largely reduced comparing to smooth Pt surface, therefore dihydroxyacetone is more favored on smaller particles. (See Fig. 3) Further characterization of the catalysts and their detailed kinetic behavior is currently under way.