Optimizing Palladium Use in Emissions Systems

One of the exciting parts of attending the SAE World Congress is the "what if" presentations, the results of innovative experimentation. While the findings, technologies and real-life applications don't currently exist, these opportunities demonstrate the possibilities the future holds. And they are endless.

This strategy to optimize Palladium usage will provide a financial benefit in the future.

Together, with engineers at Chrysler Group LLC, we questioned what would happen to light-off temperature and hydrocarbon conversion if we changed the zoning on the catalyst. Zoning in this case refers to the concentration of the Platinum Group Metal (PGM) in specific areas of the catalyst.

We shortened the zone length from 50 percent of catalyst space to 10 percent, testing at different intervals to determine performance. The same overall mass of Palladium per part was maintained but as the zoning faction decreased, concentration increased.

The result: The catalyst light-off, or operating temperature, performance peaked at a zone fraction of 15 percent.  Overall, an improvement of 18 percent or 11 mg/mi of combined NMOG+NOx emissions was obtained without using additional PGM.

The theoretical background: Catalyst performance is determined by dispersion and reaction kinetics. This experiment led to improved dispersion time by decreasing space velocity and improved reaction kinetics from increased PGM concentration.

The importance: Palladium contributes to on average 85 percent of the total precious metal cost in the emissions system. This strategy to optimize Palladium usage will provide a financial benefit in the future.

This discussion was a part of the Advanced Emission Components and Systems for Gasoline Vehicles presentation series.  It is an important conversation for us to partake in as regulations continue to influence the emission system.