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

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.