New conveyor belt-like catalyst uses electricity to turn CO2 into methane, plastic

A collaboration between researchers at the University of Bonn in Germany and the University of Montreal in Canada has led to the development of a novel catalyst material that can help synthesize methane directly from carbon dioxide (CO2) using electricity.

Even as countries look to reduce their carbon emissions in the future, climate change induced by carbon dioxide gas in the atmosphere remains a problem that must be tackled.

Since CO2 can be trapped from the atmosphere and is a relatively simple molecule to work with, researchers have also developed ways to convert it into useful products such as fuel or feedstock for other applications. Methane is one such feedstock molecule that can be produced from CO2.

Methanation of CO2

Both CO2 and methane (CH4) contain a central carbon atom, and converting the CO2 into the latter requires removing the oxygen atoms and replacing them with hydrogen atoms.

The process has been achieved before using temperatures as high as 600 Fahrenheit (320 degrees Celsius). However, this requires using fossil fuels, which release CO2 into the atmosphere, defeating the purpose of the exercise.

A research team led by Nikolay Kornienko, a professor at the University of Bonn, turned to electricity to power a reaction between CO2 and water that can produce methane.

“By using climate-friendly electricity, we can produce methane that doesn’t contribute to global warming,” said Kornienko in a statement.

Novel catalyst for methane

“The production of methane is challenging because it is necessary to carry out a reaction between a gas and a liquid,” added Kornienko. His team used a gas diffusion electrode to remove oxygen from the CO2 and replace it with hydrogen atoms sourced from water.

The problem with this approach is that while water is a reaction partner, it readily splits into hydrogen and oxygen atoms; when this happens, methane production stops, so the research team had to ensure that the water did not come in contact with the electrode.

To achieve this, the research team produced a novel catalyst that, when deposited onto the electrode, ensures that all carbon dioxide reacts more readily to make methane. Inside the catalyst are “active centers” that weaken the bonds between carbon and oxygen atoms in CO2.

To ensure that only hydrogen atoms replace the oxygen ones in the following step, the researchers bound long molecular side chains to the active center, which repels water molecules.

In addition to keeping water molecules away, these side chains double as a conveyor belt, snatching hydrogen atoms from the water and moving them to the active center, facilitating methane production.

When the new catalyst material was used, the researchers attained an 80 percent methane production efficiency without side reactions involving water splitting. Yet, the research team does not suggest that the material be used for large-scale methane production.

“The reaction principles we have achieved with this catalyst could, however, be realized in other catalyst materials for use in large-scale technical applications,” added Kornienko in a press release .

Potential applications of the technology could include the production of ethylene, which is the starting point for the production of plastics. Thus, the catalyst could make plastic production more environmentally friendly.

The research findings were published today in Nature Chemistry .