Supported silver catalysts prepared by deposition in aqueous solution of Ag nanoparticles obtained through a photochemical approach

The preparation of titania and ceria supported silver catalysts through a photochemical approach was here investigated. Ag catalysts were prepared by irradiating at 25 8C and different wavelengths (254 or 300 nm) an aqueous solution of silver acetylacetonate, successively suspending the support, after complete silver photoreduction. Catalytic behaviour and physical properties of these catalysts (LD) were compared with those of Ag samples prepared by conventional techniques, i.e. impregnation (IM) and coprecipitation (CP). Catalysts were characterized by TEM and XRD and tested in the complete oxidation of methanol. Both Ag/TiO2 and Ag/CeO2 samples prepared through the photochemical approach exhibited much higher catalytic activity in the methanol combustion than corresponding IM and CP ones. On the basis of characterization data, the higher activity of the titania supported LD sample was related to the presence of spherical, multiple twinned, highly defective Ag crystallites. In the case of the ceria supported system the better performances of the LD catalyst were explained with the formation of smaller Ag nanoparticles on this sample.