Influence of noble metals on the structural and catalytic properties of Ce-doped SnO2 systems

This paper discusses the influence of the presence of a second dopant (Pt or Pd) on the SnO2·Ce matrix. The characteristics of the material and the catalytic activity of oxidizing methanol were evaluated. Two routes were used to prepare the SnO2·5 mol% Ce·1 mol% NM (NM=Pt or Pd). Transmission electronic microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and chromatographic assays were used to study the samples. Almost no changes in the morphology were detected when the samples were prepared by the impregnation route. In contrast, preparation by the chemical route (modified polymeric precursor (MPP) route) revealed crystallite growth and CeO2 segregation. No sample showed any metallic cluster, but all the samples containing noble metal displayed a very marked catalytic property, suggesting significant activity even at room temperature. The products formed were CO2 and water, representing a competitive advantage from the standpoint of environmental protection.