By characterising current three-way catalysts (TWCs) after thermal ageing, 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 new TWC formulations (Pt/Rh and Pd/Rh) at a series of different maximum catalyst operating temperature limits (960 deg C, 1010 deg C and 1050 deg C) using a proprietary transient ageing cycle. Each catalyst was evaluated periodically throughout the ageing on a dynamic dynamometer to assess its emission performance and ageing characteristics. Through analysis of aged standard Pt- and Pd-based technology new Pt/Rh and Pd/Rh TWC formulations have been developed with enhanced thermal durability. These Pt/Rh and Pd/Rh technologies have been aged under representative transient real-world ageing conditions at different temperatures from 960 deg C to 1050 deg C. After extended ageing at 1050 deg C, both the new Pt/Rh and the new Pd/Rh TWC technologies exhibited excellent thermal durability, and were able to achieve better than European Stage IV emissions legislation on a production platform at a relatively low average PGM loading of 35 g/ft3. Minor optimisation of the engine calibration was required with the Pt/Rh technology to bring the NO(x) emissions to within the Stage IV NO(x) standard. In contrast, no calibration modifications were required to the Pd/Rh technology to achieve Stage IV emissions requirements. It has been shown that these TWC formulations can operate at higher peak temperatures than older TWC technology. This feature can be used to widen the lambda one operating window of a vehicle, which will enable improved fuel consumption. To ensure that these fuel economy benefits can be realised, it is essential that other temperature critical powertrain components are robust to these higher operating temperature regimes of the new advanced Pt/Rh and Pd/Rh TWC formulations.
High temperature stable three-way catalysts for European stage IV emissions legislation
Hochtemperaturfeste Drei-Wege-Katalysatoren für die EU-IV-Emissionsgesetzgebungsstufe
Emission Control, 1 ; 181-200
2002
20 Seiten, 24 Bilder, 3 Tabellen
Aufsatz (Konferenz)
Englisch
High Temperature Durable Three-way Catalysts to Meet European Stage IV Emission Requirements
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