Characterization of Multifunctional Catalysts for Automotive Exhaust Purification

The basic working principles and the different types of multifunctional catalysts for “three way systems” are reviewed. Test methods for multifunctional catalysts characterizing activity and stability are described. Ageing procedures in air may cause problems with rhodium containing multifunctional catalysts.

Different surface oxidation states of rhodium depending on pretreatment conditions were detected in multifunctional catalysts. The influence of those oxidation states on activity is discussed.