A new one-step process that converts carbon dioxide and water directly into liquid hydrocarbon could significantly limit global warming by removing CO2 from the atmosphere to produce fuel, chemists and engineers from the University of Texas at Arlington have discovered.
Furthermore, they claim that the process, which harnesses light, heat, and high pressure to create the sustainable fuel, would also release oxygen back into the planet’s atmosphere as a byproduct of the necessary chemical reaction, making it a win-win in terms of environmental impact.
As Frederick MacDonnell, interim chair of chemistry and biochemistry at UTA and co-principal researcher on the project, said in a statement, “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.”
MacDonnell and his colleagues demonstrated that carbon dioxide and water can be converted to liquid hydrocarbons and oxygen in a simple, one-step process using a photothermochemical flow reactor operating at 180 to 200 C and pressures up to 6 atmospheres. A paper detailing the team’s research was published Monday in the Proceedings of the National Academy of Sciences.
The goal is to produce ‘a sustainable solar liquid fuel’
“We are the first to use both light and heat to synthesize liquid hydrocarbons in a single stage reactor from carbon dioxide and water,” explained Brian Dennis, professor of mechanical and aerospace engineering at UTA and the other co-principal investigator of the project.
Dennis explained that the photochemical reaction is driven by concentrated light. The process generates high-energy intermediates and heat, which serves as the catalyst for thermochemical carbon-chain-forming reactions, allowing liquid hydrocarbons to be produced in a single step.
In their experiments, MacDonnell, Dennis and their colleagues used a hybrid photochemical and thermochemical catalyst based on titanium dioxide, a white powder that cannot absorb the entire visible light spectrum. The next step, they explained, will be to develop a photo-catalyst which is better suited to the solar spectrum so that they will be able to more effectively use other kinds of light to improve their chances of developing “a sustainable solar liquid fuel.”
Ultimately, the study authors hope to use parabolic mirrors to concentrate sunlight on the catalyst bed, which would enable them to provide both heat and photo-excitation for the process. If there were any excess heat left over from the reaction, it could be harnessed for other processes needed to produce solar fuel, such as product separation and water purification, the UTA team said.
MacDonnell and Dennis, who have received nearly $2.7 million in grants and corporate funding to study sustainable energy since 2012, are also working on a method to convert natural gas into usable high-grade diesel and jet fuel. Furthermore, MacDonnell has also working on a synthetic photosynthetic system that uses solar power to split water molecules into oxygen and hydrogen, allowing the later to be used as a clean-burning fuel.
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Image credit: University of Texas at Austin
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