The current study highlights synthesis as a key parameter for obtaining Au-Ir/Al2O3 bimetallic catalysts using the deposition-precipitation with urea (DPU) method. Both co-deposition and sequential deposition (first by adding Au and then Ir and vice versa) were employed. These approaches were compared with the sol-gel and impregnation methods, revealing notable differences in the catalytic oxidation of C3H8 at low temperatures. The Au-Ir/Al2O3 catalysts prepared via co-deposition and sequential deposition demonstrated outstanding results, producing nanoparticles as small as 1 nm when thermally reduced in hydrogen at 400 °C; also, these catalysts exhibited greater capacity for oxidizing C3H8 below 280°C than the Ir/Al2O3 and Au/Al2O3-based catalysts. Characterization of the catalysts was conducted by employing various techniques, including in-situ DRIFTS, UV-Vis, H2-TPR, HAADF-STEM-EDS, XPS and surface acidity determinations by pyridine thermo-desorption. This last technique showed differences in total acidity (Brönsted and Lewis) provoked by the Au-Ir interaction in the different catalysts, which significantly influenced their ability to oxidize C3H8 towards CO2. The results emphasize the effectiveness of the co-deposition and sequential deposition methods using the DPU approach compared to the sol-gel and impregnation methods.
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