Reducibility Studies of Ceria, Ce0.85Zr0.15O2 (CZ) and Au/CZ Catalysts after Alkali Ion Doping: Impact on Activity in Oxidation of NO and CO

Catalysts

Linjie Hu¹  Shazam Williams¹  Huitian Ju¹  Donald W. Kirk²  Wojciech Patkowski³  Marek Gliński³  Ewa Maria Iwanek (nee Wilczkowska)³  Zbigniew Kaszkur⁴  Giuseppe Pantaleo⁵  Leonarda Francesca Liotta⁵ 

[1] DCL International Inc., Concord, ON L4K 4T5, Canada;Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, 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: reducibility;    ceria;    cerium-zirconium mixed oxide;    Au catalysts;    CO oxidation;    alkali metal ions;   

DOI  :  10.3390/catal12050524

来源: DOAJ

【 摘 要 】

The aim of these studies was to perform thorough research on the influence of alkali metal ions (Li, Na, K and Cs) on the properties of nanogold catalysts supported on ceria–zirconia. The addition of alkali metal ions onto CeO₂ further affected the reducibility, which was not noted for the Zr-doped support (Ce_0.85Zr_0.15O₂). Despite the substantial impact of alkali metal ions on the reducibility of ceria, the activity in CO oxidation did not change much. In contrast, they do not have a large effect on the reducibility of Au/CZ but suppressed the activity of this system in CO oxidation. The results show that for CO oxidation, the negative effect of potassium ions is greater than that of sodium, which corresponds to the shift in the T_max of the reduction peak towards higher temperatures. The negative effect of Li⁺ and Cs⁺ spans 50% CO conversion. The negative effect was visible for CO oxidation in both the model stream and the complex stream, which also contained hydrocarbons and NO. In the case of NO oxidation to NO₂, two temperature regimes were observed for Au + 0.3 at% K/CZ, namely in the temperature range below 350 °C; the effect of potassium ions was beneficial for NO oxidation, whereas at higher temperatures, the undoped gold catalyst produced more NO₂.

【 授权许可】

Unknown