Chemists use electricity to convert waste molecules into valuable liquid fuels

A study has revealed a highly efficient method of producing methanol.

For years, chemists have been trying to synthesize valuable materials from waste molecules. Now, an international team of scientists is investigating how electricity facilitates this process.

In their study, published recently Natural catalystResearchers have demonstrated that carbon dioxide, a greenhouse gas, can be converted into a liquid fuel called methanol in a highly efficient manner.

The process took place by taking cobalt phthalocyanine (CoPc) molecules and uniformly spreading them on carbon nanotubes. GrapheneSimilar to tubes with unique electrical properties. On their surface was an electrolyte solution that, by passing an electric current through it, allowed the CoPc molecules to pick up electrons and use them to convert carbon dioxide into methanol.

Observing chemical reactions

Using a special method based on in-situ spectroscopy to visualize the chemical reaction, the researchers saw for the first time that the molecules turned themselves into methanol or carbon monoxide, which was not the desired product. They found that the path the reaction takes is determined by the environment in which the carbon dioxide molecule reacts.

Adjusting this environment by controlling how the COPC catalyst is distributed over the carbon nanotube surface allowed for eight times more carbon dioxide to be produced than methanol, increasing the efficiency of other catalytic processes and having a wider impact on others. fields, said Robert Baker, co-author of the study and professor of chemistry and biochemistry at The Ohio State University.

„When you take carbon dioxide and convert it to another product, there are many different molecules you can create,” he said. „Methanol is certainly one of the most desirable because it has a high energy density and can be used directly as an alternative fuel.”

Although the transformation of waste molecules into useful products is not a new phenomenon, until now, researchers have often been unable to see how the reaction actually occurs, an important insight for improving and optimizing the process.

„We can improve empirically how something works, but we don’t have an understanding of what makes it work, or what makes one catalyst work better than another,” said Baker, who specializes in surface chemistry. Reactions change when they occur in the face of different substances. „These are very difficult things to answer.”

Advanced Spectroscopy Techniques

But with the help of special techniques and computer modeling, the team has gotten significantly closer to understanding the complex process. In this study, the researchers used a new type of vibrational spectroscopy that allowed them to see how molecules interacted with surfaces, said Quansang Zhu, lead author of the study and a former Ohio State Presidential Scholar.

„We can tell by their vibrational signatures that it’s the same molecule sitting in two different reaction environments,” Zhu said. We were able to correlate that one of those reaction environments is responsible for producing methanol, a valuable liquid fuel.”

According to the study, in-depth analysis found that these molecules interact directly with supercharged particles called cations, which enhance the process of methanol formation.

More research is needed to learn more about what else these cations activate, but such a discovery is key to achieving a more efficient way to make methanol, Baker said.

„We’re looking at very important systems and learning things that have been wondered about for a long time,” Baker said. „Understanding the unique chemistry that occurs at a molecular level is critical to enabling these applications.”

In addition to being a low-cost fuel for vehicles such as airplanes, cars, and cruise ships, methanol produced from renewable electricity can also be used for heat and power generation and to power future chemical innovations.

„There’s a lot of exciting things that can come next based on what we’ve learned here, and some of which we’re already starting to do together,” Baker said. „Work in progress.”

Reference: „Solution environment of molecularly dispersed cobalt phthalocyanine determines methanol selectivity during electrocatalytic CO2 reduction” 8 July 2024, Natural catalyst.
DOI: 10.1038/s41929-024-01190-9

Co-authors include Conor L. Rooney and Hailiang Wang included Yale University, Hadar Shema and Elad Cross from Hebrew University, and Christina Zeng and Julian A. from Binghamton University. This work was supported by the National Science Foundation and the United States-Israel Binational Science Foundation (BSF) International Collaboration.