Supported noble metal particles (e.g., Au) on high-surface-area supports are of great importance for many reactions in the field of heterogeneous catalysis. The catalytic activities of noble metal particles are highly size-dependent as confirmed by numerous previous studies. In particular, ultrasmall noble metal nanocatalysts (UNMNs, &lt; 2 nm), referred to nanoclusters with a few to hundreds of atoms, have received substantial attention recently, since they hold a high surface-to-volume ratio and a large proportion of surface (edge and corner particularly) atoms. Our group recently reported a robust soft nitriding method to grow ligand-free ultrafine noble metal nanocatalysts (e.g., Au) onto carbon supports. In this study, we focus on the application of carbon-supported ligand-free Au nanocluster as catalysts for the selective epoxidation of C=C bonds. Using tert-butyl hydroperoxide (TBHP) as an oxidant at 80 °C, the reaction selectivity of epoxidation was found to be highly determined by solvent compositions. In case of styrene oxidation, the benzaldehyde was favorable (&gt; 80%) in apolar solvent, e.g., toluene; while the selectivity to styrene oxide increase in polar solvent, e.g., acetonitrile and water. Over 92% selectivity to styrene oxide was observed in the mixture of acetonitrile and water (80:20, vol). Moreover, similar product selectivity was seen in six other substances including: p-methylstyrene, p-chlorostyrene, o-methylstyrene, cinnamyl alcohol, cyclohexene, and cyclooctene. Our finding indicates that the carbon-gold interaction is critical to varying the kinetic pathways and to controlling the product selectivity of epoxidation.

Au-carbon electronic interaction mediated selective oxidation of styrene

254th National Meeting (2017)

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