Influence of the preparation method and dopants nature on the WGS activity of gold catalysts supported on doped by transition metals ceria

Gold catalysts supported on ceria doped by different metal oxides (Me = Fe, Mn, Sn) were synthesized by two different methods: coprecipitation (CP) and mechanochemical activation (MA). Samples were characterized by means of XRD, HRTEM, TPR and XPS. Both XRD and HRTEM analyses reveal differences in the average size of the gold and ceria particles. As shown by TPR data, ceria doping improves oxygen mobility, i.e. a higher oxygen capacity was observed while compared with gold catalyst on undoped ceria. The method of preparation and the nature of dopant applied influence the catalytic performance in the water-gas shift (WGS) reaction. The differences in WGS activity between the MA and CP samples were significant. The MA catalysts, doped by Fe and Mn, manifested higher WGS activity than the undoped Au/ceria sample and the sample doped by Sn. A high concentration of Ce3+ ions in the highly active catalysts containing Fe or Mn was registered by XPS and found consistent with an earlier proposed model of the active sites for the WGS reaction. (C) 2013 Elsevier B.V. All rights reserved.