Combination of theory and experiment shows how a three-part catalyst helps transform excess CO2 into usable ethanol.
An international collaboration of scientists has taken a significant step toward the realization of a nearly “green” zero-net-carbon technology that will efficiently convert carbon dioxide, a major greenhouse gas, and hydrogen into ethanol, which is useful as a fuel and has many other chemical applications. The study reports a “roadmap” for successfully navigating this challenging reaction and provides a picture of the full reaction sequence using theoretical modeling and experimental characterization.
Led by the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, the group determined that bringing cesium, copper, and zinc oxide together into a close-contact configuration catalyzes a reaction pathway that transforms carbon dioxide (CO2) into ethanol (C2H6O). They also discovered why this three-part interface is successful. The study, which is described in a paper in the July 23, 2021, online edition of the Journal of the American Chemical Society and is featured on the publication’s cover, will drive further research into how to develop a practical industrial catalyst for selectively converting CO2 into ethanol. Such processes will lead to technologies that are able to recycle CO2 emitted from combustion and convert it into usable chemicals or fuels.
None of the three components examined in the study is able to individually catalyze the CO2-to-ethanol conversion, nor can they in pairs. But when the trio is brought together in a certain configuration, the region where they meet opens a new route for the carbon-carbon bond formation that makes the conversion of CO2 to ethanol possible. The key to this is the well-tuned interplay between the cesium, copper, and zinc oxide sites.
“There has been much work on carbon dioxide conversion to methanol, yet ethanol has many advantages over methanol. As a fuel, ethanol is safer and more potent. But its synthesis is very challenging due to the complexity of the reaction and the difficulty of controlling C-C bond formation,” said the study’s corresponding researcher, Brookhaven chemist Ping Liu. “We now know what kind of configuration is necessary to make the transformation, and the roles that each component plays during the reaction. It is a big breakthrough.”
The interface is formed by depositing tiny amounts of copper and cesium onto a surface of zinc oxide. To study the regions where the three materials meet, the group turned to an x-ray technique called in x-ray photoemission spectroscopy, which showed… Brinkwire News Summary.