Carbon dioxide becomes ethanol with metal help

Researchers have found a way to turn CO₂ into ethanol, using cobalt and copper.

The method, which works at a lab scale, is another potential way to use carbon dioxide captured from the atmosphere and industrial processes – although capturing that carbon is still a difficult task.

The team has published their discovery in ACS Catalysis.

“We can remove the greenhouse gas CO₂ from the environment and reintroduce it into a sustainable carbon cycle,” says co-author Professor Carsten Streb, a chemist at Johannes Gutenberg University Mainz, Germany.

There are a variety of techniques scientists are working on to react carbon dioxide with other materials and turn it into useful chemicals.

“To achieve this, we require suitable catalysts capable of this conversion with high selectivity so that we obtain a high yield of the desired product, which – in our case – is ethanol,” says Streb.

Ethanol can be used as a feedstock for other chemicals, or as a fuel. Using it as a fuel would emit CO₂ back into the atmosphere, making this process circular rather than carbon-negative.

Copper has shown promise as a catalyst for reacting with CO₂, and is much cheaper and more abundant than many of the other catalysts used, like palladium or platinum, but it’s generally less efficient and selective.

These researchers developed an electrode, covered with a powder made from a very finely tuned combination of cobalt and copper, using electron microscopy to ensure the surface formed properly.

“The initial challenge is to get carbon dioxide to react,” says Streb. “The bonds between the atoms of the molecule are very strong, but cobalt can break them.”

This causes carbon monoxide to form, which the copper then turns into ethanol.

The researchers tested their substance in a CO₂-saturated environment. Atmospheric concentrations of CO₂, at around 420 parts per million, are much lower.

In this environment, they were able to convert 80% of the carbon dioxide into ethanol.