Researchers Synthesize Catalyst to Eliminate Pollutants from Vehicle Exhaust at Ambient Temperature

Scientists from Washington State University, University of New Mexico, Eindhoven University of Technology, and Pacific Northwest National Laboratory have synthesized a catalyst that could potentially endure high temperatures and convert contaminants at about ambient temperature—a significant progress in lowering pollution in present-day cars.

The study has been published in Nature Communications.

Since 1970s, catalytic converters have been used in the United States as a means to eliminate pollutants from vehicle exhaust. Rare metals, like platinum, have been used in a catalytic reaction to convert CO and other pollutants into harmless N₂, CO₂, and H₂O.

But cars have become highly fuel-efficient due to low energy consumption and low exhaust gas temperature, making them difficult to get rid of the pollutants. Indeed, the U.S. Department of Energy has aimed at removing 90% of hazardous emissions at ≤150 °C.

The catalysts not only have to act upon at low temperatures but also ought to exist under severe conditions experienced during the reaction.

The catalyst problem has increased paradoxically as cars have become better and more efficient.

Emiel Hensen, Catalysis Professor, Eindhoven University of Technology.

At the same time, the industry also faces difficulties with the high cost of the rare metals needed for catalysis. For example, although platinum eases chemical reactions for several often-used products and processes, it costs >$800 per ounce.

The scientists synthesized the catalyst based on the activation of single atoms of platinum supported on CeO₂. This catalyst has outclassed the existing technology and reduced the quantity of platinum required, thereby minimizing the overall costs.

The industry wants to make use of every single atom of the precious metals, which is why single-atom catalysis has attracted increased attention.

Abhaya Datye, Distinguished Professor, Department of Chemical & Biological Engineering, University of New Mexico.

In their current study, the scientists first made sure their catalysts were thermally stable, capturing platinum ions on a CeO₂ support at extremely high temperatures. Their method of synthesis led the platinum atoms to firmly bond to their support. Later, they activated the catalyst in CO at approximately 275 °C.

To our surprise, we discovered that the high temperature synthesis made the ceria more easily reducible, allowing it to provide a key ingredient—oxygen—to active sites.

Yong Wang, Voiland Distinguished Professor, Gene and Linda Voiland School of Chemical Engineering and Bioengineering, WSU.

Next, at the platinum sites, the activated oxygen had the potential to remove pollutants at about ambient temperature.

This research directly addresses the 150-degree challenge identified by the U.S. Department of Energy and by automobile companies. The discovery of oxygen activation at near room temperature is extremely useful, and this finding could have a significant impact on the technology of exhaust emission control.

Yong Wang, Voiland Distinguished Professor, Gene and Linda Voiland School of Chemical Engineering and Bioengineering, WSU.

At present, the goal of the scientists is to examine the performance of single-atom catalysts with other pollutants and organic compounds.

This study was financially supported by the U.S. Department of Energy’s Office of Basic Energy Sciences and Netherlands Research Center for Multiscale Catalytic Energy Conversion.