Efficient carbon conversion unlocked

Researchers in the US have found a new, more efficient method to create carbon-based fuels from carbon dioxide.

The researchers discovered a new additive that helps selectively convert CO₂ into fuels containing multiple carbon atoms. This could be a step closer to making renewable liquid fuels not derived from coal or oil.

Desirable fuel

Professor Jonas Peters, from the California Institute of Technology, said: “The results were quite shocking. Usually, in these types of reactions with CO₂, you see a lot of byproducts like methane and hydrogen. In this case, the reaction was highly selective for the more desirable fuels that contain multiple carbons – such as ethylene, ethanol, and propanol.”

Fuels with multiple carbon atoms are desirable as they tend to be liquid, resulting in more energy per volume than gaseous fuels. For instance, propanol is liquid and contains three carbon atoms, storing more energy than methane, a gas with one atom.

Professor Peters, alongside other scientists, is working at the Joint Centre for Artificial Photosynthesis (JACP) to create multi-carbon fuels. Established in 2010, this research program aims to establish a renewable hydrocarbon fuel sector that recycles CO₂ using solar energy.

The scientists used an aqueous solution and a copper electrode which served as both a catalyst and source of energy in place of the sun. CO₂ was added to the solution along with N-substituted arylpyridiniums - organic molecules which form a very thin deposit on the electrode. For reasons not fully understood, the film dramatically improves the reaction creating ethanol, ethylene and propanol. Professor Peters said: “We saw an 80 percent conversion to these multi-carbon fuel products, with only 20 percent or so going into hydrogen and methane.”

The researchers’ next step will see how additives enhance this reaction. Similar additives will also be tested to see if they can further improve selectivity for the desired fuels. Progress in this field could lead to alternate fuels being created efficiently from sunlight, CO₂ and water instead of oil.

The paper was published in ACS Central Science.