Selective CO oxidation with nano gold particles-based catalysts over Al2O3 and ZrO2

We present the preparation, characterization and catalytic evaluation of gold-based catalysts over Al(2)O(3), ZrO(2) and 10% ZrO(2)/Al(2)O(3) in selective CO oxidation. Oxidation and reduction pretreatments were evaluated using in situ X-ray diffraction, and the size of gold particles was determined. All catalysts contained gold particles in the range of 2-5 nm, with as-prepared samples containing a mixture of gold species (Au(3+) and Auo). The catalytic tests showed complete CO oxidation at temperatures lower than 100 degrees C, with Au/ZrO(2) sample presenting the best performance. Both the support and pretreatment conditions were found to cause changes to gold species. In situ X-ray diffraction patterns indicated the presence of different gold phases and of nanometer-scale crystallites of gold, which was confirmed by transmission electron microscopy results. It was also found that cationic gold improved the activity of Au/ZrO(2). Concerning stability, time on stream tests showed that all samples were stable to coke deposition and sintering. (c) 2008 Published by Elsevier B.V.