Carbon dioxide is leaking from industrial operations into the atmosphere, causing a cascade of dangerous changes to Earth’s climate. But some scientists wondered if instead it could instead be captured and converted to useful chemicals.
A group of scientists with Argonne National Laboratory and the University of Chicago, Northern Illinois University and Valparaiso University, have showed how to make a family of catalysts that can efficiently convert CO2 into ethanol, acetic acid or formic acid.
These are among the most produced chemicals in the U.S. and are found in many commercial products. For example, ethanol is a key ingredient in numerous household products and an additive to nearly all U.S. gasoline.
“If fully developed, our catalysts could convert the CO2 produced at various industrial sources to valuable chemicals,” said Di-Jia Liu, a senior chemist at Argonne and a senior scientist in the Pritzker School of Molecular Engineering at the University of Chicago. “These sources include fossil fuel power plants and bio-fermentation and waste treatment facilities.”
The method used by the team is called electrocatalytic conversion, meaning that CO2 conversion over a catalyst is driven by electricity.
The catalysts are based on tin metal deposited over a carbon support. By varying the size of tin from single atoms to ultra-small clusters and also to larger nano-crystallites, the team could control the CO2 conversion to acetic acid, ethanol and formic acid, respectively. Selectivity for each of these chemicals was 90% or higher.
“Our finding of a changing reaction path by the catalyst size is unprecedented,” Liu said.
‘A win-win situation’
Because the reaction does require electricity, in order to make the technology fully green, Liu said the goal is to use locally generated electricity from wind and solar.
This would require integrating the newly discovered catalysts into a low-temperature electrolyzer to carry out the CO2 conversion with electricity supplied by renewable energy. Low-temperature electrolyzers can operate at near ambient temperature and pressure. This allows rapid start and stop to accommodate the intermittent supply of renewable energy; it is an ideal technology to serve this purpose.
“If we can selectively produce only the chemicals in need near the site, we can help to cut down on CO2 transport and storage costs,” Liu noted. “It would truly be a win-win situation for local adopters of our technology.”
This research benefited from two user facilities at Argonne — the Advanced Photon Source and Center for Nanoscale Materials.
Citation: “Modulating CO2 Electrocatalytic Conversion to the Organics Pathway by the Catalytic Site Dimension.” Xu et al, Journal of the American Chemical Society, April 4, 2024.
Funding: U.S. Department of Energy, Argonne Laboratory Directed Research and Development
—Adapted from an article by Joseph Harmon first published by Argonne National Laboratory.
—Prof. Jacqueline Stewart
