Influence of Preparation Method of Ag–CeO2 Catalysts on Their Structure and Activity in Soot Combustion

Resumo

The exhaust gases from motor vehicles contain unburned soot particles that pollute the environment and have a detrimental effect on the human health. The solution to this problem requires the development of new highly efficient Pt- and Pd-less catalysts for the oxidation of soot in exhaust gases. In the present work, the catalysts based on the Ag–CeO₂ composition were synthesized by two techniques (co-precipitation and incipient wetness impregnation) and characterized by a complex of physicochemical methods (low-temperature nitrogen adsorption, powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM HR) and temperature-programmed oxidation (TPO)). The catalytic properties of the catalysts were studied in the reaction of soot oxidation. It was shown that the Ag–CeO₂ catalyst prepared by the coprecipitation method was the most active in soot oxidation. The increased activity of the catalyst was associated with the formation of a complex structure, representing an agglomerate of strongly interacting silver and ceria particles, which significant affect the low-temperature activation of oxygen on the catalyst surface as shown by the TPO method.