Chemists use electricity to turn waste molecules into valuable liquid fuels

A study has discovered a more efficient method for creating methanol.

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

In their study, recently published in Nature’s Catalysisresearchers demonstrated that carbon dioxide, a greenhouse gas, can be converted into a type of liquid fuel called methanol in a very efficient manner.

This process took place by taking cobalt phthalocyanine (CoPc) molecules and spreading them evenly across carbon nanotubes. graphene-like tubes that have unique electrical properties. On their surface was an electrolyte solution, which, by passing an electric current through it, allowed the CoPc molecules to receive electrons and use them to convert carbon dioxide into methanol.

Observation of chemical reactions

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

Tuning this environment by controlling how the CoPc catalyst was distributed on the carbon nanotube surface allowed carbon dioxide to be up to eight times more likely to produce methanol, a discovery that could increase the efficiency of other processes catalytic and have a far-reaching impact on others. field, said Robert Baker, co-author of the study and professor of chemistry and biochemistry at Ohio State University.

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

While the transformation of waste molecules into useful products is not a new phenomenon, until now, researchers have often been unable to observe how the reaction actually occurs, an essential insight to be able to optimize and improve the process.

“We can empirically optimize how something works, but we don’t really have an understanding of what makes it work, or what makes one catalyst work better than another catalyst,” said Baker, of who specializes in surface chemistry, the study of how chems. reactions differ when they occur on the site of different objects. “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 the complex process. In this study, the researchers used a new type of vibrational spectroscopy that allowed them to see how molecules behave on surfaces, said Quansong Zhu, lead author of the study and former Ohio State Presidential Scholar, whose challenging measurements were vital to the discovery.

“We could tell from their vibrational signatures that it was the same molecule sitting in two different reaction environments,” Zhu said. “We were able to link that one of those reaction environments was responsible for the production of methanol, which is a valuable liquid fuel.”

According to the study, deeper analysis also revealed that these molecules interact directly with charged particles called cations that enhance the methanol formation process.

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

“We’re seeing systems that are very important and learning things about them that have been asked for a long time,” Baker said. “Understanding the unique chemistry that occurs at a molecular level is really important to enable these applications.”

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

“There are a lot of exciting things that could come next based on what we’ve learned here, and some of them we’ve already started to put together,” Baker said. “The work is ongoing.”

Reference: “Solution Environment of Molecularly Dispersed Cobalt Phthalocyanine Determines Methanol Selectivity During Electrocatalytic Reduction of CO2” by Quansong Zhu, Conor L. Rooney, Hadar Shema, Christina Zeng, Julien A. Panetier, Elad Gross, Hailiang Wang and L. Robert Baker, July 8, 2024, Nature’s Catalysis.
DOI: 10.1038/s41929-024-01190-9

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