Modern Alchemy: University of North Dakota Aims to Turn Corn Stalks, Stems and Leaves into Jet Fuel

(University of North Dakota/News Wise) One of the significant challenges for renewable alternative fuels could be solved if a consortium of research laboratories led by the University of North Dakota can turn corn waste into jet fuel.

Seames, who will use post-doctorates, graduate and undergraduate students from UND’s chemical engineering and chemistry programs on the project, likens the role of modern chemical engineers to 17^th century alchemists. They sought ways to turn low-value metals such as lead into gold.

“When I tell students that chemical engineers are basically alchemists, they relate to it,” Seames said. “We’re always taking things with less value and turning them into things with more value, whether it’s linking them to a new fuel or taking a waste stream and making it less harmful to the environment.”

A team of scientists and engineers with UND’s ND SUNRISE (Sustainable Energy Research Initiative and Supporting Education) research center will develop a process to convert the lignin contained in corn stover – the stalks, stems and leaves left over after corn is harvested – into jet fuel. Lignin is a polymer that, along with cellulose, forms the structural support of plants.

“About 70 percent of corn stover goes back on to the field to renew the soil,” Seames explained. “That leaves about 30 percent available to use as a biomass raw material. You can imagine that with all the corn we grow in the U.S., that’s millions of tons of product.”

Making jet fuel from plant material is especially challenging, both for safety reasons and for providing enough energy density to enable a jet aircraft to fly the same distance as an airplane using conventional fuel.

“Jets fuels are extremely difficult to formulate,” Seames said. “You need a very high energy density, a very low freezing point and a very low volatility.”

The goal of the DOE research project is to extract cyclohexane compounds from the lignin for use as a jet fuel feedstock. Seames said it’s a complex process based on technology developed at Washington State University (WSU) in Pullman, Wash., by a research team led by Bin Yang, associate professor in biological systems engineering.

Seames outlined the various processes the corn stover will go through before it becomes jet fuel. First, corn stover will be bought from farmers by DOE’s Idaho National Laboratory, where it will be dried, chopped and powdered. It will then be shipped to DOE’s National Renewable Energy Laboratory (NREL) in Golden, Colo., to undergo a process that removes the sugars from the lignin to form a base reactive solution – similar to pickling liquor. This solution will be shipped to UND for further processing and testing.

“This is where Washington State’s technology comes in,” Seames explained. “We'll be working with the catalyst formulation WSU invented. Dr. Yang and his team will be working with a catalyst manufacturer, Advanced Refining Technology, to pelletize the catalyst so that we can put it in the continuous reactors we’ll be building. After providing the initial catalyst, WSU will be working on formulating an improved version of its catalyst, which will then be reoptimized at UND.”

Seames said the reactive lignin solution will be routed through the reactor with hydrogen at high pressure and high temperature.

“The hydrogen and temperature in the presence of the catalyst is going to break the lignin apart and reform it into organic compounds,” he said. “The ones we’re targeting are known as cyclohexanes. These are essentially a non-aromatic version of benzene compounds. The advantage of using cyclohexanes is that they provide the same desirable properties of aromatics for jet fuel, but they aren’t as corrosive or as toxic.”

Once the solution has been optimized, UND researchers will produce a prototype jet fuel that will be sent to the University of Dayton in Ohio for fuel specification testing.

“They’ll be running a series of tests there to compare our samples to the current industry specifications,” Seames noted.

Another project requirement is to demonstrate that the reaction in UND’s engineering-scale reactor can run for at least 100 hours continuously and 500 hours in total.

Seames said UND’s participation and leadership in the project is the result of ND SUNRISE’s reputation for the development and commercialization of renewable fuel technologies.

“We were approached by researchers at NREL and WSU who were looking for a partner with the experience and capability to take WSU’s lab-scale batch reaction and develop it into a larger scale continuous system,” Seames said. "We are looking forward to helping develop this technology towards commercialization with these great university and laboratory partners." READ MORE