Gold supported on partially dehydroxylated γ-Al2O3 was prepared from Au(CH3)2(C5H7O2). The activities of the materials as CO oxidation catalysts were investigated following pretreatment in flowing O2 and, alternatively, in flowing CO. The catalytic activity data are complemented with extended X-ray absorption fine structure and X-ray absorption near edge structure spectra recorded as the samples in flow reactors were treated in O2, in CO, and in CO + O2 while functioning as CO oxidation catalysts. Mass spectrometry was used to identify the gases evolved during the treatments. The data show that samples pretreated in O2 contained predominantly cationic gold and were more active as catalysts than samples pretreated with CO, which contained gold predominantly as zerovalent clusters. These results reinforce recent reports of the role of cationic gold in the catalytic sites for CO oxidation.
© by Oldenbourg Wissenschaftsverlag, München