Researchers at the University of Bonn and the University of Montreal have developed a revolutionary catalyst that efficiently converts carbon dioxide and water into methane using electricity. This innovative process has the potential to produce methane in a highly sustainable manner, making it largely climate-neutral when powered by green electricity.
Their findings could pave the way for large-scale production of methane and other vital chemical compounds. This breakthrough has the potential to revolutionize the energy and chemical industries, offering a sustainable solution for a wide range of applications.
“We used electricity as the driving force instead,” explains Prof. Dr. Nikolay Kornienko. “By using climate-friendly electricity, we can produce, for example, methane that doesn’t contribute to global warming.”
The researcher recently made a move from the University of Montreal to the Institute of Inorganic Chemistry at the University of Bonn, where he continued and completed his latest groundbreaking study. “The production of methane – which has the chemical formula CH4 – is challenging because it is necessary to carry out a reaction between a gas and a liquid,” says Kornienko.
In this case, the focus is on the reaction between carbon dioxide (CO2) and water (H2O). To bring these two crucial components together, the researchers utilized a gas diffusion electrode. This reaction involves the separation of the two oxygen atoms (O) from the carbon atom (C) and their replacement with four hydrogen atoms (H) sourced from the water.
The challenge with this process is that water eagerly undergoes a different reaction, splitting into hydrogen and oxygen upon exposure to an electric current.
“This is a competing reaction that we have to avoid,” emphasizes Kornienko’s assistant Morgan McKee, who carried out a large proportion of the experiments. “Otherwise, it would stop us from producing any methane. Therefore, we have to prevent the water from coming into contact with the electrode. At the same time, we still need the water as a reaction partner.”
A newly developed catalyst deposited onto the electrode is the game-changer. It ensures that carbon dioxide reacts more readily and rapidly to produce methane. This is made possible by its “active center,” which not only captures the carbon dioxide but also weakens the bonds between the carbon atom and the two oxygen atoms.
In the subsequent stage, these oxygen atoms are gradually replaced by four hydrogen atoms. The catalyst requires water at this point but must also keep it at a distance to prevent any undesired side reactions.
“In order to achieve this, we bound long molecular side chains to the active center,” explains Prof. Kornienko, who is also a member of the Transdisciplinary Research Area “Matter” at the University of Bonn. “Their chemical structure repels water or, in other words, they are hydrophobic.”
This groundbreaking process, derived from the Greek term for “having a fear of water,” not only keeps H2O molecules away from the active center and the electrode but also acts as a conveyor belt, figuratively snatching hydrogen atoms from water molecules and transporting them to the active center where they react with the carbon atom, ultimately converting CO2 into CH4 in several steps.
With an efficiency of over 80 percent and minimal production of undesired side products, this process sets a new standard. Although not suitable for large-scale methane production, its principles could be adapted into other catalyst materials for widespread technical applications, according to Kornienko.
This revolutionary method isn’t limited to methane production. It has the potential to significantly impact the production of other chemical compounds, such as ethylene, a key raw material for plastics manufacturing. In the near future, this catalyst method could play a pivotal role in making plastic production more environmentally friendly.
Journal reference:
- Morgan McKee, Maximilian Kutter, Yue Wu, Hannah Williams, Marc-Antoine Vaudreuil, Mariolino Carta, Ashok Kumar Yadav, Harishchandra Singh, Jean-François Masson, Dieter Lentz, Moritz F. Kühnel & Nikolay Kornienko. Hydrophobic assembly of molecular catalysts at the gas–liquid–solid interface drives highly selective CO2 electromethanation. Nature Chemistry, 2024; DOI: 10.1038/s41557-024-01650-6
