Simple one-step process to convert water, CO2 into fuel

Scientists have successfully shown that carbon dioxide and water can be directly converted into usable liquid hydrocarbon fuels in a one-step process by using concentrated light, heat and high pressures.
This simple and inexpensive new sustainable fuels technology could potentially help limit global warming by removing carbon dioxide from the atmosphere to make fuel.
The process also reverts oxygen back into the system as a byproduct of the reaction, with a clear positive environmental impact, researchers said.
"Our process also has an important advantage over battery or gaseous-hydrogen powered vehicle technologies as many of the hydrocarbon products from our reaction are exactly what we use in cars, trucks and planes, so there would be no need to change the current fuel distribution system," said Frederick MacDonnell, from University of Texas at Arlington.

The researchers demonstrate that the one-step conversion of carbon dioxide and water into liquid hydrocarbons and oxygen can be achieved in a photothermochemical flow reactor operating at 180 to 200 degrees Celsius and pressures up to 6 atmospheres.
"We are the first to use both light and heat to synthesise liquid hydrocarbons in a single stage reactor from carbon dioxide and water," said Brian Dennis, professor at UTA.

"Concentrated light drives the photochemical reaction, which generates high-energy intermediates and heat to drive thermochemical carbon-chain-forming reactions, thus producing hydrocarbons in a single-step process," Dennis said.
The hybrid photochemical and thermochemical catalyst used for the experiment was based on titanium dioxide, a white powder that cannot absorb the entire visible light spectrum.

"Our next step is to develop a photo-catalyst better matched to the solar spectrum," MacDonnell said.
"Then we could more effectively use the entire spectrum of incident light to work towards the overall goal of a sustainable solar liquid fuel," he said.
The researchers envision using parabolic mirrors to concentrate sunlight on the catalyst bed, providing both heat and photo-excitation for the reaction.
Excess heat could even be used to drive related operations for a solar fuels facility, including product separations and water purification.
The study was published in the journal PNAS.