Pt–Ag Bimetallic Catalysts Supported on Mesoporous Silica MCM-41 in 4-Nitrophenol Reduction

Mesoporous silica MCM-41 with a specific surface area of 1134 m²/g was prepared. It was used to manufacture supported mono- and bimetallic Pt–Ag catalysts with various metal ratios by incipient wetness impregnation. After the reductive high-temperature treatment of Pt–Ag catalysts, Pt and Ag metal nanoparticles contacting with one another were formed on the surface of the support as shown by X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). The bimetallic catalysts showed an increased reactivity in TPR-H₂ compared to the relevant monometallic catalysts due to the interaction of AgO_x and PtO_y centers. The catalysts were tested in the reduction of 4-nitrophenol with sodium borohydride. A significant increase in 4-nitrophenol reduction rate over bimetallic catalysts was due to the synergistic effect of platinum and silver.