Surface modification of γ-Al₂O₃ with bimetallic Pt–Cu nanoparticles: role of Pt–Cu interaction in the catalytic oxidation of C₃H₈

The incorporation of Cu into the Pt/Al₂O₃ catalyst significantly promoted its performance in the catalytic oxidation of C₃H₈. The bimetallic Pt-Cu catalyst supported on non-reducible γ-Al₂O₃ revealed strong Pt-Cu interaction, as well as the highest activity toward the total oxidation of C₃H₈. Its performance surpassed that of the monometallic Pt/Al₂O₃ and Cu/Al₂O₃ catalysts, showing a synergetic effect while maintaining excellent stability under both dry and wet reaction conditions. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed that Pt sites act as the main active centers, facilitating C₃H₈ adsorption due to the low-frequency bands associated with CO adsorption on low-coordination bridging Pt sites. Also, the adsorption of both C₃H₈ and O₂ was more favorable on the Pt–Cu bimetallic surface than on the individual Pt or Cu catalysts, presumably because of the lower coordination environment of the active sites. During the in-situ reaction, intermediates such as acetates and enolates were detected, which were rapidly oxidized to CO₂. Furthermore, strong Lewis acid sites and surface hydroxyl groups seemed to promote C–H bond cleavage at low temperatures.