The Effect of High Temperature Ageing on Platinum-Rhodium and Palladium-Rhodium Three Way Catalysts

The durability of platinum-rhodium and palladium-rhodium three way catalysts has been investigated after ageing at elevated temperatures. Catalysts were subjected to inlet temperatures of between 780 and 960 °C for periods up to 100 hours on an engine bench. It may be concluded that platinum-rhodium catalysts have a better resistance to ageing at catalyst inlet temperatures above 840 °C than palladium-rhodium catalysts at the same loading. A new formulation palladium-rhodium catalyst loaded at 60 g/ft3 and a ratio of 9:1 showed substantially improved high temperature durability.