The preparation and characterization of silica-supported PtNi catalysts

Abstract In this work we have utilized a relatively simple procedure to produce silica-supported bimetallic Ni Pt catalysts. During deposition-precipitation nickel reacts with the support to form nickel hydrosilicate and simultaneously platinum is adsorbed onto the reacting support. Platinum appears to facilitate the hydrogen reduction of the nickelhydrosilicate. Electron micrographs of reduced and passivated catalysts show the presence of small particles with diameters ranging from 2 to 8 nm depending on the metal loading, a relatively narrow particle size distribution, and crystallites densely and homogeneously dispersed over the support. By infrared experiments we have shown that reduction results in the formation of alloy particles. It is established that the surface composition of the reduced alloy particles is not too different from the bulk deposition. Oxidation leads to a surface enrichment in nickel. The alloys are found to be stable in an oxidizing atmosphere.