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In order to meet recent and future stringent hydrocarbon emission regulations of passenger cars, the use of Pd-containing catalysts is of growing interest. This is especially true for Pd/Rh and Pt/Pd/Rh catalysts. To optimize the function of the individual precious metals, most high-performance catalysts have a double layer configuration. This double layer avoids undesired interactions between Pd and Rh after reacting with exhaust gas at a high temperature level. Of course, these double layer technologies lead to a more complex capacity utilization coating process during the manufacture of the catalyst. The present work summarizes the results of a research program targeting the development of a high-performance single layer Pd/Rh catalyst technology. The starting point was the functional improvement of Pd and Rh only catalysts then subsequently combining the best of these technologies.

Zirconium dioxide (zirconia) is a well-known material often being a major component in the washcoat systems of three-way catalysts (TWC) and diesel oxidation catalysts. One important characteristic of zirconia containing washcoats is an improved aging stability which is required to meet the more and more stringent emission standards. In the last few years the utilization of zirconia became even more important - especially for high sophisticated three-way washcoat systems. This was due to the development of high temperature stable oxygen storage components, containing cerium dioxide (ceria) in combination with different other oxides - one very promising candidate being zirconia. In the present work the results of a research program are discussed, focusing on the influence of zirconia in combination with ceria and additional rare earth promoters on the stability of the oxygen storage characteristics.