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With the implementation of Euro V emissions legislation in 2010, the vast majority of light-duty diesel vehicles now employ a diesel particulate filter. The expansion of the Diesel Euro V standard outside Europe is inhibited in part by the low availability of ≺50 ppm sulfur fuel. Having said this, countries such as India and China have ≺50 ppm sulfur fuel available in many urban centers today, with the geographical area covered growing each year. Whilst it is well known that diesel DPF applications require ≺50 ppm sulfur fuel for optimum long-term operation, the ability of the system to withstand periodic "high" sulfur events would be a useful enabler for the early implementation of Euro V legislation to these markets. In this paper, the authors set out to assess the capability of the DOC and cDPF exhaust gas aftertreatment system to cope with periodic high sulfur fuel events.

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.

The prevention of automotive releases of the unpleasant smelling hydrogen sulfide (H2S) is highly desirable. However, the ability to routinely test catalysts for dynamic H2S releases corresponding to the real world has traditionally proved difficult. The work herein identifies the key steps taken to produce a highly repeatable (overall relative standard deviation of typically less than 10%) procedure capable of replicating H2S releases from wide-open throttle (WOT) events. The testing utilized a chassis dynamometer to test a gasoline vehicle (fitted with one TWC system) over a specific transient drive cycle with H2S emissions detected using a chemical ionization mass spectrometer and an infra-red detection based system. The importance of the warm-up and catalyst preparation parts of the test are discussed, including statistical analysis. A repeatable and short test suited to rapid developmental screening of potential catalyst systems is also presented.