Minimizing low temperature emissions through advances in metal oxide catalysts, supports and traps

Todd  Toops, Oak Ridge National Laboratory

Removing the harmful pollutants in automotive exhaust has been an intense focus of the automotive industry over the last several decades. Current state-of-the-art catalysts achieve 90% conversion of pollutants between 200 °C and 350 °C and consequently, more than 50% of the emissions occur in the first 2-3 minutes under cold-start or idling conditions. While such performance enables meeting current emission standards, as emissions regulations become more stringent meeting the emission regulations will require increased activity during this warm-up period. To further complicate matters, the increased Corporate Average Fuel Economy (CAFE) standards that will be implemented over the next decade will result in the introduction of more fuel-efficient engines. This will result in lower exhaust temperatures, which further necessitates the need for increased emissions control activity at low temperatures. These low temperature issues are expected to affect a wide range of powertrain options to meet the fuel economy standards including diesel vehicles, gasoline-powered vehicles, and hybrid electric vehicles.

This presentation will outline ongoing research to minimize criteria emissions through the optimization of metal oxides for catalysis, catalytic supports, and as trap materials. The first area that will be discussed is the study of improvements of conventional PGM-based oxidation catalysts with a focus on how modifying the metal oxide support can lead to improved activity. The second approach discussed will be the investigation of novel metal-oxides that are not currently being used in emissions control catalysts, with an emphasis on non-PGM materials. The third system discussed will highlight trap materials and what temperatures a family of materials is active for hydrocarbons and NOx.

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