An XPS Study of the Oxidation of Noble Metal Particles Evaporated onto the Surface of an Oxide Support in Their Reaction with NOx

作者：Smirnov M Yu^*; Vovk E I; Kalinkin A V; Pashis A V; Bukhtiyarov V I

来源：Kinetics and Catalysis, 2012, 53(1): 117-124.

DOI：10.1134/S0023158412010132

The interaction of the model catalysts Rh/Al2O3, Pd/Al2O3, Pt/Al2O3, and Pt/SiO2 with NOx (mixture of 10 Torr of NO and 10 Torr of O-2) was studied by X-ray photoelectron spectroscopy (XPS). Samples of the model catalysts were prepared under vacuum conditions as oxide films >= 100 angstrom in thickness on tantalum foil with evaporated platinum-group metal particles. According to transmission electron microscopic data, the platinum-group metal particle size was several nanometers. It was found by XPS that the oxidation of Rh and Pd nanoparticles in their interaction with NOx occurs already at room temperature. The particles of platinum were more stable: their oxidation under the action of NOx was observed at elevated temperatures of similar to 300 degrees C. At room temperature, the interaction of platinum nanoparticles with NOx hypothetically leads to the dissolution (insertion) of oxygen atoms in the bulk of the particles with the retention of their metallic nature. It was found that dissolved oxygen is much more readily reducible by hydrogen than the lattice oxygen of the platinum oxide particles.

• 出版日期2012-2