Au–Pd alloying-promoted thermal decomposition of PdO supported on SiO 2 and its effect on the catalytic performance in CO oxidation

Abstract

We have prepared a series of Au–Pd/SiO 2 catalysts by the routine deposition–precipitation method followed by calcination at 200 °C in air for 4 h. The structures of these catalysts have been characterized with powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and H 2-temperature-programmed reduction. Their catalytic activity in CO oxidation has also been studied. We found that the preparation procedure leads to the formation of highly dispersed PdO supported on SiO 2 in Pd/SiO 2, but to the formation of both highly dispersed PdO and Au x Pd alloy nanoparticles in Au–Pd/SiO 2 catalysts. The fraction of metallic Pd in Pd species increases with the increase of Au:Pd molar ratio in Au–Pd/SiO 2 catalysts. We proposed that the alloying of Au and Pd can promote the thermal decomposition of PdO supported on SiO 2. Because of the existence of metallic Pd, Au–Pd/SiO 2 catalysts are more active in CO oxidation than Pd/SiO 2. Au–Pd/SiO 2-0.5 exhibits the same activity as Pd/SiO 2-H 2 in CO oxidation. Our results provide some novel information on the fabrication of supported Au x Pd alloy nanoparticles.