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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 ch combustion

Catalysts, ISSN: 2073-4344, Vol: 10, Issue: 6, Page: 1-13
2020
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Article Description

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 O showed good agreement with the CO activity trend in tests performed in a complex stream of reagents, which also contained CH, CH, CH, NO, and water vapor. The results of the X-ray Diffraction (XRD) studies revealed that the support has the composition CeZrO, 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 H 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 T 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 T 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.

Bibliographic Details

Ewa M. Iwanek (nee Wilczkowska); Leonarda F. Liotta; Shazam Williams; Linjie Hu; Krishelle Calilung; Giuseppe Pantaleo; Zbigniew Kaszkur; Donald W. Kirk; Marek Gliński

MDPI AG

Chemical Engineering; Environmental Science; Chemistry

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