Effect of the Chemical Atmosphere of the Thermolysis of the Complex PdAg2(OAc)4(HOAc)4 on the Formation of Active Centers in Pd–Ag/CeO2 Catalysts for the Low-Temperature Oxidation of Carbon Monoxide

Resumo

The Pd–Ag/CeO₂ catalysts were prepared by the impregnation of highly dispersed CeO₂ with a solution of the heteroatomic complex PdAg₂(OAc)₄(HOAc)₄. Samples obtained after the thermolysis of PdAg₂(OAc)₄(HOAc)₄ in N₂ and H₂ contained Pd–Ag alloy and Pd particles immobilized on CeO₂. The Pd⁰–CeO₂ metal oxide centers formed at the interface were highly active in the low-temperature reaction of CO oxidation. The particles of Pd were absent from the Pd–Ag/CeO₂ sample prepared by the decomposition of PdAg₂(OAc)₄(HOAc)₄ in an atmosphere of O₂; in this case, a significant portion of the Pd–Ag phase was covered with a film of CeO₂, which dramatically slowed down the rate of reaction at low temperatures.