Au/Rutile Catalysts: Effect of the Activation Air Flux on the Catalytic Activity for CO Oxidation and the Gold Crystallite Size

详细信息    查看全文

• 作者：Xim Bokhimi ; Rodolfo Zanella ; Antonio Morales
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：August 14, 2008
• 年：2008
• 卷：112
• 期：32
• 页码：12463-12467
• 全文大小：169K
• 年卷期：v.112,no.32(August 14, 2008)
• ISSN：1932-7455

文摘

Gold was supported on nanocrystalline rutile and activated with an air flux between 150 and 850 mL/min to catalyze the oxidation of CO. The corresponding catalysts were characterized by X-ray powder diffraction and refinement of the crystalline structures. The catalytic activity depended on the air flux and had a maximum at 600 mL/min; the activity difference was caused by the variation of the gold crystallite size and morphology with the air flux. The catalyst with the maximum activity had an average gold crystallite with the morphology of a cuboctahedron with depressed Au(100) faces. The quantitative analysis also provided the surface area, volume, specific area, and dimensions and morphology of the average crystallites. An analysis of the dependence of these parameters on the air flux showed that they were not fundamental parameters explaining the catalytic activity. The quantitative analysis also provided the number of gold atoms in the average gold crystallites: 96, 59, 56, and 21 for the samples prepared at 150, 300, 600, and 850 mL/min. It is discussed that, as in microscopic large gold crystallites, the surface properties of the supported gold crystallites could be determined by the reordering of the atom distribution on Au(100) crystallite faces, caused by the relativistic effects on electrons in 5d orbitals.