High Temperature Durable Three-way Catalysts to Meet European Stage IV Emission Requirements

By characterizing current three-way catalysts (TWCs) after thermal aging, it was possible to use the information obtained to develop a new generation of more thermally durable TWCs. To assess their performance, a dynamic dynamometer was used to age these new TWC formulations (Pt/Rh and Pd/Rh) at a series of different maximum catalyst operating temperature limits (960, 1010 and 1050°C) using a proprietary transient aging cycle. Each catalyst was evaluated periodically throughout the aging on a dynamic dynamometer to assess its emission performance and aging characteristics. After a representative aging time, both the Pt/Rh and the Pd/Rh formulations were capable of meeting European Stage IV emission standards on a production powertrain after prolonged 1050°C aging. The thermal resistance of the new Pt/Rh and Pd/Rh TWCs is significantly better than that of previous technologies. They could be used in close-coupled locations allowing broadened lambda-one operation during high speed driving, thereby minimising the use of overfuelling and improving fuel economy. To realise these benefits it is essential other temperature critical components are robust at the higher temperatures the new advanced catalyst technologies can withstand.