Structure Sensitivity of Acrolein Hydrogenation by Platinum Nanoparticles on BaxSr1-xTiO3 Nanocuboids

摘要

The structure sensitivity of Pt nanoparticles (Pt-N) for gas-phase acrolein (AC) hydrogenation was probed for Pt-N on BaxSr1-xTiO3 nanocuboid supports with (001) facets in a combined theoretical and experimental study. The insitu selectivity for allyl alcohol increased with the increase of the Sr concentration in the support, which corresponds to modifications in the stable Winterbottom shape and lattice strain of the Pt nanoparticles as a result of the interfacial energy between Pt and the BaxSr1-xTiO3 supports. "Local model" nanofacets of the Pt surface, edge, and corner morphologies were developed as compact representations of adsorption and reaction sites. DFT was used as the primary modeling tool for the equilibrium adsorption states. We argue that adsorption on edge sites is critically important for the overall allyl alcohol selectivity of Pt-N catalysts. A simple model was developed to represent Pt-N strain effects caused by its interaction with the substrate. Bader topological atom, spherical volume averaging charge, and modified bond valence sum analyses were used to understand the bonding structure. Density of states analysis was performed for the structures of Pt-N, adsorbed AC, and intermediate products to examine adsorbate-particle interactions. The simulated hydrogenation of AC on Pt-N nanofacets was compared to the insitu hydrogenation of AC by Pt-N on BaxSr1-xTiO3 to examine the effects of facet, edge, and corner sites on the overall selectivity.