Illinois Researchers Pair Nanocatalysts, Food Waste to Reduce Carbon Emissions in Aviation

For researchers from the University of Illinois Urbana-Champaign, a new avenue for reducing carbon emissions can be found on the side.

A side of salad dressing, that is.

In 2020, the United States federal government committed to achieving net-zero carbon emissions by 2050. An important step toward carbon neutrality is embracing sustainable aviation fuel (SAF), an alternative to conventional jet fuel that is made from renewable feedstocks. As part of this initiative, Illinois engineers have been hard at work creating the critical nanocatalysts for converting biocrude oil from food waste such as salad dressing into sustainable aviation fuel.

Hong Yang, a professor of chemical & biomolecular engineering in the College of Liberal Arts & Sciences, and Yuanhui Zhang, a professor of agricultural & biological engineering in the Grainger College of Engineering, joined forces to tackle this problem.

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Their findings, published in Science Advances, present a low-cost, scalable and reusable catalyst to produce an alternative to traditional jet fuel, demonstrating the first production of SAF from food waste-derived biocrude using non-noble metal carbide catalysts.

"There is already an industry effort for SAF production in North America, but primarily in competition with food supply such as soybean oil," said Zhang. "Currently, the United States consumes about 40 million tons of jet fuel annually which only includes about 1% of SAF. We could increase that number to 10-20% from biowaste alone."

Unlike traditional jet fuels derived from fossil crude oil, SAF is made from renewable resources such as biomass, energy crops, food waste, sewage sludge, and algal bloom. For nearly three decades, Zhang’s lab has been working to produce biocrude oil via hydrothermal liquefaction (HTL) of organic waste streams. HTL mimics the natural process of fossil crude formation but accelerates the conversion timeline from millions of years to half an hour.

Yang and Zhang thought that by simultaneously addressing carbon emissions and food waste they could kill two birds with one stone.

After collecting food waste from the Kraft Heinz food plant in Champaign, Illinois, the researchers used HTL to convert the waste into a biocrude oil. This biocrude was upgraded using non-precious metal carbide catalysts developed by Yang’s lab.

"Molybdenum carbide is an attractive option for a catalyst that aids this process because its outer shell electrons interact with biocrude molecules to remove oxygen," Yang said.

For their specific food waste of choice, the team quickly zeroed in on salad dressing because it is preprocessed, homogenous and high in energy. Through a catalytic conversion process, scientists can remove unwanted oxygen in these biocrudes, turning them into hydrocarbon fuels.

"We also have to fine tune the catalysts by adding iron atoms and other species to produce fuel molecules with molecular weights that resemble the fuel composition" said Siying Yu, a chemical & biomolecular engineering graduate student and the first author of the paper.

Going forward, Zhang and Yang will continue collaborating with the goal of enhancing their catalyst design to better convert biocrude made from other biowaste to meet SAF criteria. Specifically, they’d like their catalyst to work for a variety of bio feedstocks such as algae and sewage. The metal carbide nanocatalysts they developed could also be appliable in studying SAF production from oleochemical-based fermentation products and crop-based feedstocks.

"There is no good substitute for aviation fuel for long-haul air transportation, so the research on SAF products is very much needed." Yang said. "I’m optimistic because our students love this research topic. They want to work on something that will change the world."

Other co-authors on this study included Haozhen He, Runnan Gao and Anran Song of the Department of Chemical & Biomolecular Engineering; Sabrina Summers and Buchun Si of the Department of Agricultural & Biological Engineering; and Zhibin Yang and Joshua Heyne of Washington State University. Yang is affiliated with the Department of Chemistry, the Materials Research Laboratory, the Prairie Research Institute, and the Center for Advanced Bioenergy and Bioproducts Innovation.

This study was supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency & Renewable Energy, Bioenergy Technologies Office; DOE Center for Advanced Bioenergy and Bioproducts Innovation, Office of Science, Office of Biological and Environmental Research; and Federal Aviation Administration Office of Environment and Energy through ASCENT, the FAA Center of Excellence for Alternative Jet Fuels and the Environment.

The paper "Upgrading biocrude oil into sustainable aviation fuel using zeolite-supported iron-molybdenum carbide nanocatalysts" is available online.