Application of Potassium Ion Deposition in Determining the Impact of Support Reducibility on Catalytic Activity of Au/Ceria-Zirconia Catalysts in CO Oxidation, NO Oxidation, and C3H8 Combustion

Catalysts

Linjie Hu¹  Shazam Williams¹  Krishelle Calilung¹  DonaldW. Kirk²  EwaM. Iwanek (nee Wilczkowska)³  Marek Gliński⁴  Zbigniew Kaszkur⁵  LeonardaF. Liotta⁶  Giuseppe Pantaleo⁶ 

[1] DCL International Inc., Concord, ON L4K 4T5, Canada;Department of Chemical Engineering and Applied Science, University of Toronto, Toronto, ON M5S3E5, Canada;Faculty of Applied Science and Technology, Sheridan College, Brampton, ON L6Y5H9, Canada;Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland;Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland;Istituto per lo Studio di Materiali Nanostrutturati (ISMN)-CNR, I-90146 Palermo, Italy;

关键词: CO oxidation;    potassium poisoning;    gold nanoparticles;    ceria-zirconia;    NO oxidation;    propane combustion;   

DOI  :  10.3390/catal10060688

来源: DOAJ

【 摘 要 】

The purpose of the study was to show how a controlled, subtle change of the reducibility of the support by deposition of potassium ions impacts the activity of gold catalysts. Since the activity of supported gold catalysts in carbon monoxide oxidation is known to strongly depend on the reducibility of the support, this reaction was chosen as the model reaction. The results of tests conducted in a simple system in which the only reagents were CO and O₂ showed good agreement with the CO activity trend in tests performed in a complex stream of reagents, which also contained CH₄, C₂H₆, C₃H₈, NO, and water vapor. The results of the X-ray Diffraction (XRD) studies revealed that the support has the composition Ce_0.85Zr_0.15O₂, that its lattice constant is the same for all samples, and that gold is mostly present in the metallic phase. The reducibility of the systems was established based on Temperature Programmed Reduction (TPR) and in situ XRD measurements in H₂ atmosphere. The results show that the low temperature reduction peak, which is due to the presence of gold, is shifted to a higher value by the presence of 0.3 at% potassium ions on the surface. Moreover, the increase of the potassium loading leads to a more pronounced shift. The T₅₀ of CO oxidation in the simple model stream was found to exhibit an excellent linear correlation with the maximum temperature of the low temperature reduction peak of Au catalysts. This means that stabilizing oxygen with a known amount of potassium ions can be numerically used to estimate the T₅₀ in CO oxidation. The results in the complex stream also showed a similar dependence of CO conversion on reducibility, though there was no substantial difference in the activity of the catalysts in other reactions regardless of the potassium loading. These studies have shown that the influence of potassium varies depending on the reaction, which highlights differences in the impact of reducibility and importance of other factors in these reactions.

【 授权许可】

Unknown