Trace Pd alloyed with Au to boost Au/uncalcined TS-1 catalyzed propane hydro-oxidation to acetone

Selective oxidation of propane to acetone (AC) with H₂ and O₂ provides a direct route to convert low-cost propane into value-added products. Unfortunately, the catalytic activity of conventional Au/Ti-based catalysts is constrained by the high energy barrier for H₂ dissociation. Herein, uncalcined TS-1 supported Au-Pd bimetallic catalysts were prepared, and the relationship between the active-site structure and corresponding performance in the selective oxidation of propane with H₂ and O₂ in the gas phase was systematically investigated. In contrast to the liquid-phase reaction, trace Pd alloyed with Au triggered an increase in both catalytic activity and selectivity, in which Au₂₀-Pd₁/TS-1-B catalyst exhibited excellent activity (170 g_AC·h⁻¹·kg_cat⁻¹) and AC selectivity (90.6%), much higher than those of the Au/TS-1-B catalyst (AC formation rate of 100 g_AC·h⁻¹·kg_cat⁻¹ and AC selectivity of 86.3%). It was found that Pd was gradually isolated into monomers with the increase of Au/Pd molar ratio, and the synergy between Pd single atoms and Au improved the catalytic performance via enhancing hydrogen dissociation and modulating the electronic structure of Au. Furthermore, the reaction conditions were optimized based on the kinetics studies and the Au₂₀-Pd₁/TS-1-B catalyst exhibited enhanced H₂ selectivity (45%) and long-term stability (over 130 h). The insights gained here can offer valuable guidance for the design of Au-Pd catalysts applicable to other gas-phase oxidation reactions.