A comparative study of Cu, Ag and Au doped CeO2 in the total oxidation of volatile organic compounds (VOCs)

• IB metals (Au, Ag and Cu) were supported on ceria (CeO2) by two different methods.
• The solids were tested as catalysts for total oxidation of propylene and toluene.
• The deposition-precipitation is better for Au whereas for Ag and Cu it is the impregnation.
• High oxidation states of gold and silver and clusters of copper enhanced catalytic behavior.
• Catalytic activity is linked to the oxidation/reduction potential of the redox IB couples.

Total oxidation of two Volatile Organic Compounds (VOCs), propylene and toluene, was investigated over M/CeO2 catalysts, where M is a metal from IB group (i.e. Au, Ag, Cu), prepared by two different methods: the conventional wet impregnation and the deposition-precipitation. The catalysts have been characterized by means of total surface area (BET), X-ray diffraction (XRD), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance ultra-violet-visible spectroscopy (DR-UV/Vis), and temperature-programmed reduction (TPR), in order to explain the differences observed in their catalytic activity towards the studied reactions. By comparing the two different preparation methods, the presence of metal in high oxidation state for gold and silver, and the presence of clusters for copper were the main factors responsible for the high catalytic activity. This latter was also found to be related, when comparing the different IB metals, to the values of the oxidation/reduction potential of the redox couples of the different metals.

Figure optionsDownload as PowerPoint slide