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Alex Bowser

Science/Tech Editor

akb6244@psu.edu

Researchers from the Nature Communications journal have shown promise in a new chemical reaction using an iron-based catalyst converting carbon dioxide into jet fuel, which could reduce the amount of pollution caused by the aviation industry.

Carbon dioxide is part of the greenhouse gases that are polluting Earth’s atmosphere through jet engines and is involved in many other processes that burn fossil fuels. Currently, oil is used to make jet fuel, which pumps out carbon dioxide into the environment. Because of this, the carbon footprint produced by airlines makes up 12 percent of CO2 emissions from global transportation.

There have been studies conducted that all try to convert carbon dioxide into fuel one way or another, which most required expensive materials and complex chemical reactions. However, the new catalyst is a powder that is both inexpensive using cheap materials including iron and transforms the CO2 from one chemical conversion process.

When scientists forced carbon dioxide and hydrogen gas to react with one another, they used the iron-based catalyst to separate the carbon atoms from the oxygen atoms and link them with the hydrogen. The result formed hydrocarbon molecule used in jet fuel, while the leftover oxygen atoms formed with the remaining hydrogen to create water.

Dr. Tiancun Xiao, along with some of his colleagues, works in chemistry at the University of Oxford. In order to test the catalyst, they used a small reaction chamber, pressurized to about 10 times the air pressure at sea level, and was set at a temperature of 300 degrees Celsius. In addition to the catalyst and hydrogen atoms, they also added citric acid, manganese, and potassium. 

In just over 20 hours, 38 percent of the carbon dioxide was converted into new chemical compounds, with almost half of the compounds being jet fuel hydrocarbons. The remaining by-products included other types of petrochemicals such as ethylene and propylene, which are used in making plastics and could also be helpful.

“Climate change is accelerating, and we have huge carbon dioxide emissions,” says Dr. Xiao. “The infrastructure of hydrocarbon fuels is already there. This process could help relieve climate change and use the current carbon infrastructure for sustainable development.”

Scientists and researchers are now hopeful in an industry where air travel could potentially be carbon neutral by burning the same amount of carbon used in jet fuel that is in return used to manufacture the fuel itself. In Dr. Xiao’s perspective, there seems to be “no big challenges” in implementing this change, only the “need to optimize the process and make it more efficient.”

However, there is still some concern for how quickly we can see carbon-based jet fuel. Joshua Heyne, an associate professor of mechanical and chemical engineering at the University of Dayton, says that “it looks like it could work,” but believes that “scale-up is always an issue, and there are new surprises when you go to larger scales. But in terms of a longer-term solution, the idea of a circular carbon economy is definitely something that could be the future.”

Oskar Meijerink is a project lead for future fuels at SkyNRG, a Dutch-based firm that works in producing sustainable jet fuel to buy and sell to airports worldwide. He, too, believes that this could also come with issues, but believes that the issue lies in how environmentally-friendly the carbon fuel is.

“You need to use renewable electricity,” Meijerink says. “The challenge is if we are using CO2 from a steel mill, how can we push the steel mill to be carbon neutral itself? The perfect solution would be to have all these industries be more sustainable, and use this to do direct-air capture.”

Even so, Oxford’s new carbon-dioxide-based jet fuel will have to wait its turn, as there are numerous other alternatives currently in the works of being tested in the hopes of being approved and used as alternatives to traditional jet fuel. Most of these alternatives come from feedstocks and use municipal solid waste, straw, woody biomass, and even waste cooking oil, which is a process being pursued by BP.

Despite the competition, Dr. Xiao still believes that the carbon dioxide jet fuel is more than able to compete and even trump the other alternatives. Dr. Xiao is trying to team up with Velocys, a green fuel firm in the works of developing alternative aviation fuels for companies such as Shell and British Airways, the same firm that is currently using municipal waste.