The researchers said this simple and inexpensive sustainable fuels technology could potentially help limit global warming by removing CO2 from the atmosphere to make fuel. The process also reverts oxygen back into the system as a byproduct of the reaction.
Frederick MacDonnell, UTA interim chair of chemistry and biochemistry, 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.”
The team’s the one-step conversion of CO2 and water into liquid hydrocarbons and oxygen can be achieved in a photothermochemical flow reactor operating at 180 to 200°C 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, UTA professor of mechanical and aerospace engineering. "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."
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."
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.
MacDonnell and Dennis' investigations are also focused on converting natural gas for use as high-grade diesel and jet fuel. Additionally, MacDonnell has worked on developing photocatalysts for hydrogen generation, with the goal of creating an artificial photosynthetic system which uses solar energy to split water molecules into hydrogen and oxygen. The hydrogen could then be used as a clean fuel.
