A catalyst using just one or a few palladium atoms removed 90% of unburned methane from natural gas engine exhaust at low temperatures in a recent study. While more research needs to be done, the development of single-atom catalysis has the potential to reduce exhaust emissions of methane, one of the worst greenhouse gases that trap heat at about 25 times the rate of carbon dioxide.
Journal reporting, Catalysis in Naturea research effort between Washington State University and SLAC National Accelerator Laboratory showed that the single-atom catalyst was able to remove methane from engine exhaust at low temperatures, below 350 ° Celsius (662 ° Fahrenheit), while maintaining of the stability of the reaction at higher temperatures .
“It’s almost a self-modulating process that miraculously overcomes the challenges that humans struggle with—low-temperature inactivity and high-temperature instability,” said Yong Wang, Regents Professor at WSU’s Gene and Linda Voiland School of Chemical Engineering and Bioengineering and is a corresponding author. on paper.
Natural gas engines are used in about 30 million to 40 million cars worldwide and are popular in Europe and Asia. It is also used by the gas industry to run compressors that pump natural gas into people’s homes. It is generally considered cleaner than gasoline or diesel engines, producing less carbon and particulate pollution.
However, when these natural gas-powered engines start, they release unburned, heat-resistant methane because their catalytic converters don’t work at low temperatures. Catalysts for methane removal are ineffective at lower exhaust temperatures or they degrade severely at higher temperatures.
“There’s a big drive to use natural gas, but if you use it for combustion engines, there’s always unburned natural gas from the exhaust, and you have to find a way to get that out. Otherwise, it will cause more severe global warming,” said co-author Frank Abild-Pedersen, a staff scientist at the SLAC National Accelerator Laboratory. “If you can get 90% of the methane out of the exhaust and keep the reaction stable, that’s huge.”
A single-atom catalyst with active metals individually dispersed on a support also uses every atom of expensive and precious metals, Wang added.
“If you can make them more reactive, that’s the icing on the cake,” he said.
In their work, the researchers were able to show that their catalyst made from single palladium atoms on a cerium oxide support efficiently removed methane from the exhaust of the engine, even when starting the engine.
They found that the trace amount of carbon monoxide that is always present in the engine exhaust plays a major role in the dynamic formation of active sites for the reaction at room temperature. Carbon monoxide helps a palladium atom migrate to form a two- or three-atom cluster that effectively breaks down methane molecules at low temperatures.
Then, as the exhaust temperatures rise, the sub-nanometer-sized clusters are dispersed into single atoms again so that the catalyst becomes thermally stable. This reversible process enables the catalyst to work efficiently and utilize every palladium atom the entire time the engine is running—including when it’s started from cold.
“We really found a way to keep the supported palladium catalyst stable and highly active and because of the different skills of the whole team, to understand why this happened,” said Christopher Tassone, a scientist of staff at the SLAC National Accelerator Laboratory and co-author of the paper.
Researchers are working to further improve the catalyst technology. They want to better understand why palladium behaves one way while other precious metals such as platinum behave differently.
The research has a way to go before it can be put inside a car, but researchers are working with industry partners as well as the Pacific Northwest National Laboratory to someday move the work closer. of commercialization.
In addition to Wang, Abild-Pedersen, and Tassone, Dong Jiang, senior research associate at the Voiland School, also led the work.
Dynamic and reversible transformation of subnanometre-sized palladium on ceria for efficient methane removal, Catalysis in Nature (2023). DOI: 10.1038/s41929-023-00983-8
Provided by Washington State University
Citation: Catalyst could control methane emissions from natural gas engines (2023, July 20) retrieved July 20, 2023 from https://phys.org/news/2023-07-catalyst-methane-emissions -natural-gas.html
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