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Insights into size-dependent activity and active sites of Au nanoparticles supported on TS-1 for propene epoxidation with H2 and O2

Feng, Xiang, Duan, Xuezhi, Qian, Gang, Zhou, Xinggui, Chen, De, Yuan, Weikang
Journal of catalysis 2014 v.317 pp. 99-104
catalysts, catalytic activity, epoxidation reactions, gold, hydrogen, models, nanogold, oxygen, propylene
Propene epoxidation with H2/O2 is a typical structure-sensitive reaction. For a given support containing tetra-coordinated Ti species such as TS-1, the catalytic activity is greatly influenced by supported Au nanoparticle size. The identification of size-dependent activity of Au catalyst was achieved over a series of Au nanoparticles (2.6–5.1nm) deposited on the exterior surface of TS-1 by employing uncalcined TS-1. Through this approach, we could obtain very stable Au catalysts with distinguishable and uniform-sized Au particles, which are critical for structure-sensitivity analysis. The PO formation rate (molPO s⁻¹molAu⁻¹) over these catalysts was found to vary with average Au diameter (d) as d⁻².⁷±⁰.³. Moreover, typical Au nanoparticles on uncalcined TS-1 appeared as truncated cuboctahedron with top facet of (111). Model calculations derived from the representative Au particle shape and the above size-dependent activity were then performed to show that corner sites of Au nanoparticles are dominant Au active sites for propene epoxidation.