By RYOSUKE NONAKA/ Staff Writer
April 5, 2021 at 07:00 JST
Regulations have been tightened on air pollutants in exhaust emissions from diesel vehicles. (Asahi Shimbun file photo)
KYOTO—A research team said it has developed a durable alloy that can remove nitrogen oxides from automobile exhaust and is 90 percent cheaper than a conventional material that costs more than gold.
“Exhaust purification falls in the technological field Japan is good at, so we want to make the new material commercially available,” said Kohei Kusada, an associate professor of chemistry at Kyoto University, who is part of the team.
Rhodium, a high-performance rare metal, is currently used to remover nitrogen oxides, primary air pollutants in automobile exhaust. Its demand has been growing as stricter emission control regulations are introduced around the world.
Rhodium can cost up to 100,000 yen ($916) per gram, far more expensive than gold, which is typically priced between 6,000 yen and 7,000 yen per gram.
Researchers are trying to develop an alternative substance with a purification ability similar to rhodium.
The research team has been involved in the development of a substance made up of ruthenium and palladium, which have atomic numbers 44 and 46, respectively. Their figures are around the proton number of 45 for rhodium.
The material could remove nitrogen oxides from exhaust gas, but it was too fragile to be used repeatedly.
In the latest endeavor, the scientists added an element known as iridium to ruthenium and palladium to create an alloy consisting of the three rare metals. They confirmed the alloy can be repeatedly used in a stable manner for exhaust purification.
The scientists are now working with automakers to carry out a durability test of the new material under practical conditions.
The team’s research results were published in the German scientific journal Advanced Materials.
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