Dec
27
Cleaner Cooler Catalyst For Cleaner Running Cars
December 27, 2017 | 2 Comments
The catalyst uses single atoms of platinum on a cerium oxide surface, is stable at the high exhaust temperatures of a working engine but is active at the lower “cold-start” temperatures of today’s more efficient engines. Image Credit: Cortland Johnson, Pacific Northwest National Lab. Click image for the largest view.
As cars become more fuel efficient, less heat is wasted out the exhaust, which makes it harder to clean up the pollutants being emitted. The work of researchers at Washington State University, Pacific Northwest National Laboratory and the University of New Mexico in creating the catalyst has been published in the journal Science.
The team’s work explored a successful way to create a more powerful catalyst while using smaller amounts of platinum – the most expensive component of emission-control catalysts.
Catalysts have been an integral part of diesel and gasoline-powered engines since the mid-1970s when federal regulations began requiring reductions of carbon monoxide, hydrocarbons and nitrogen oxides. Catalytic converters convert the pollutants to benign gases such as nitrogen, carbon dioxide and water.
The researchers addressed the daunting challenge of designing a catalyst that could endure engine exhaust temperatures of up to nearly 750º Celsius (about 1,500º Fahrenheit) encountered under high engine loads. Yet the catalyst would still have to work when an engine is started cold and must clean up the exhaust before reaching 150º Celsius – more than 100º Celsius less than current systems.
Abhaya Datye, a distinguished professor at the University of New Mexico’s Department of Chemical & Biological Engineering and study co-author explained the lower operating temperatures during cold start are due to increasing fuel efficiency in advanced combustion engines, which leaves less thermal energy in the tailpipe exhaust.
The recent findings grew out of a collaboration between research groups led by Yong Wang, who holds a joint appointment in Washington State University’s Gene and Linda Voiland School of Chemical Engineering and Bioengineering and the Pacific Northwest National Laboratory, and Datye’s catalysis group at New Mexico.
The work builds on research, published in Science last year, in which the Wang and Datye groups found a novel way to trap and stabilize individual platinum atoms on the surface of cerium oxide, a commonly used component in emissions control catalysts. The so-called single-atom catalyst uses platinum more efficiently while remaining stable at high temperatures. Platinum typically trades at prices close to or even greater than gold.
For their latest paper, the researchers steam-treated the catalyst at 750º Celsius, nearly 1,400º Fahrenheit. This made the already stable catalyst become very active at the low cold-start temperatures.
Wang noted, “We were able to meet the challenges of both the high-temperature stability and the low-temperature activity.”
This is very welcome news on a technology front that is gaining more efficiency each year. It seems to answer the cleaning catalyst problem at lower operating temperatures that increased efficiency is driving forward. It may also answer the question of solving a problem creating a new one quite elegantly.
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It seems to answer the cleaning catalyst problem at lower operating temperatures that increased efficiency is driving forward.
It may also answer the question of solving a problem creating a new one quite elegantly.