A Washington State University-led multi-institutional research team has received a $2.5 million Department of Energy grant that aims to reduce the use of rare and expensive metals in catalytic converters. The project will lower auto manufacturing costs while reducing air pollution.
The team includes the University of New Mexico (UNM), Pacific Northwest National Laboratory and industry partners BASF and Fiat Chrysler. The project is one of 55 nationwide to support new and innovative advanced vehicle technologies.
“This is really about working closely with industry partners to meet emission requirements and to solve national needs,” said Yong Wang, Voiland Distinguished Professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering who is leading the project. “Everyone drives a car, and nobody wants to pay an extra $500.”
Catalytic converters have been used in the U.S. since the 1970s as a way to clean up pollutants from vehicle exhaust. In the catalytic process, precious and scarce metals, such as platinum, palladium and rhodium, are needed to convert carbon monoxide and other pollutants to non‑toxic carbon dioxide, nitrogen, and water.
Increasingly stringent emission standards in recent years as well as the increased popularity of larger vehicles have driven up demand and the price of these rare elements – from a global industry cost of $19 billion in 2018 to a whopping $54.6 billion in 2020. A gram of rhodium costs over $70.
Because of their expense and scarcity, industries are continually looking to use less of these platinum group metals. Unfortunately, during their use at high temperatures, the metal atoms required for the reactions tend to mobilize and fly together into clumps, which reduces catalyst efficiency and performance. This is the primary reason catalytic converters are tested regularly for effectiveness and why manufacturers are forced to use greater amounts of precious metals.
In 2016, UNM and WSU researchers developed thermally durable single-atom catalysts by trapping metal atoms on the surface of cerium oxide, a chemical compound that is commonly used in emission control catalysts. The single-atom catalyst they developed can perform reactions at the low temperatures that are needed for more efficient engines while also surviving the harsh conditions encountered during driving. In this project, the team will apply the same concept to capture palladium and rhodium atoms for catalytic reactions.
The research team aims to reduce the amount of platinum group metals in the converter systems by about three or four times, using a maximum of 2.5 grams of palladium and .3 grams of rhodium in each vehicle. Such a reduction would save between $360 to $820 per vehicle and up to $14.3 billion for the industry.
“This DOE funding allows us to work with industry partners to take our initial discovery into commercial practice,” says Abhaya Datye, Distinguished Regents Professor and Chair of Chemical and Biological Engineering who directs the research at UNM. “It is exciting to get a chance to test catalysts developed in our laboratory under real world conditions.”