Complete Oxidation of CO, Ethanol, and Ethyl Acetate over Copper Oxide Supported on Titania and Ceria Modified Titania

Abstract

Titania and titania modified with 3 and 12 μmol Ce/m2surface area of the titania were prepared and were used as supports for copper oxide. Preparations with 3 and 12 μmol CuOx/m2surface area of the support were tested for the combustion of CO, ethyl acetate, and ethanol. The results show that the Ce-doped titania surface is good as support for CuOxand that the cerium not only enhances the activity of the copper species, but also stabilises the surface area of the TiO2support in the presence of copper oxide. Additions of Al, K, and La are also found to stabilise the TiO2support but, compared with Ce, these elements do not to the same extent enhance the activity of the copper species. Acetaldehyde is observed to be an intermediate in the combustion of both ethanol and ethyl acetate over Cu-Ce-Ti-O catalysts. Since acetaldehyde is more harmful than any of the reactants and also is photochemically active, it is in applications important to assure that the combustion is complete. Cu-Ce-Ti-O catalysts show good performance not only for feeds without water vapour, but also for humid feeds. Although the concentrations of intermediates are affected by the addition of water, there is little effect on the temperature required for obtaining complete conversion to carbon dioxide and water. Characterisation with XRD, FT-Raman, TPR, and XPS indicates that the dispersed copper species are in the form of patches or a bidimensional layer which interacts with the surface of the support. When the content of cerium and copper is low, other types of dispersed copper species are present, which possibly are monomers or dimers. The copper species are predominantly Cu2+species.