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Relationship between Atomic Scale Structure and Reactivity of Pt Catalysts: Hydrodeoxygenation of m‑Cresol over Isolated Pt Cations and Clusters

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posted on 2019-12-16, 05:32 authored by Joaquin Resasco, Feifei Yang, Tong Mou, Bin Wang, Phillip Christopher, Daniel E. Resasco
Atomically dispersed late transition-metal cations have attracted significant attention as next-generation heterogenous catalysts. However, relationships between the catalytic behavior of atomically dispersed metal cations and active sites on metal nanoparticles have been difficult to establish, in large part because of the difficulty in characterizing the local atomic structure of these metal species. Here, we use the hydrodeoxygenation (HDO) of m-cresol, a model bio-oil compound, to understand relationships between metal structure and reactivity down to the limit of atomically dispersed active sites. Through a combination of kinetic studies, spectroscopic characterization, and density functional theory calculations, we find that isolated Pt cations supported on TiO2 are significantly less active than small Pt clusters for m-cresol HDO due to their lower activity for hydrogen dissociation and their weaker interaction with m-cresol. We demonstrate that m-cresol HDO reaction kinetics are particularly sensitive to the active Pt structure, suggesting that the catalytic reactivity can be a more reliable indicator of catalyst structure than commonly used characterization approaches. These findings provide insights into the ability of isolated Pt cations to catalyze elementary processes critical for hydrogenation catalysis.

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