Higher gold atom efficiency over Au-Pd/TS-1 alloy catalysts for the direct propylene epoxidation with H2 and O2

Bimetallic nanoparticles (NPs) have shown amazing charm for their unique structures and catalytic activity. Herein, AuPd alloy NPs with cuboctahedron structure supported on titanium silicalite-1 (denoted as Au-Pd/TS-1) were prepared by the alcohol reduction method, which exhibited higher gold atom efficiency for the direct propylene epoxidation than the traditional Au/TS-1-DP (prepared by the deposition precipitation method). A combination of experimental characterization with density functional theory (DFT) calculations indicates that the charge transfer from Pd to Au atoms promotes the formation of H₂O₂ from O₂ and H₂, and consequently improves the gold atom efficiency of Au-Pd/TS-1 alloy catalysts. The volcano-shaped relationship was established between Pd/Au molar ratio and catalytic activity. Au_0.68Pd_0.32/TS-1 showed the highest gold atom efficiency of ~1000 g_PO h⁻¹ g_Au⁻¹ at 200 °C. The insights reported here may pave the way for unraveling the catalyst structure-catalytic activity relationship of supported nano-gold catalysts.