Comparison Between Turnover Rates of CO Oxidation over Rh0 or Rh x+ Supported on Model Three-Way Catalysts.

The kinetics of CO oxidation over two catalytic sites, either 100% zero-valent or 100% oxidised rhodium atoms, were studied. It was shown that an oxidised rhodium species exhibits a significant higher turnover rate in CO oxidation (factor 25) than the corresponding zero-valent one. This noticeable difference, interpreted with respect to mechanistic considerations, led us to conclude that one of the promoting effects of ceria–zirconia is to stabilise rhodium atoms as oxidised species. [ABSTRACT FROM AUTHOR]