Scientists at USDA’s Agricultural Research Service in Peoria, Ill., Have come up with a way to make better biofuel for airplanes from soybean oil.
The fatty acids in soybean oil can be made into a range of industrial products normally made from petroleum, including fuel, ink, and paints. One of the attractions of herbal products is that they recycle carbon from the atmosphere. This makes plants a much more renewable resource than oil and other fossil fuels, which add carbon to the atmosphere when they are mined from the earth and used.
However, soybean jet fuels developed to date contain insufficient amounts of “aromatics”, which impart desirable density to the fuel and help keep the gaskets in jet engines smooth and functioning properly. The current lack of aromatic levels in soy-based jet fuel means that less can be blended with conventional petroleum-derived jet fuels, explained Ken Doll, a research chemist at the National Center for Agricultural Use Research. ‘ARS in Peoria.
Blends using biofuels are one of the ways in which the aviation industry strives to reduce its ‘carbon footprint’, or total greenhouse gas emissions, particularly carbon dioxide (which were to 905 million tonnes in 2018).
One approach to making soybean jet fuel relies on using a precious metal called ruthenium to catalyze reactions that chemically alter the structure and properties of unsaturated fatty acids in the oil. The problem with this approach is that it generates too few aromatics, noted Doll, with the ARS centre’s Bio-Oil Research Unit.
To get around the problem, he and his fellow ARS scientists Bryan Moser and Gerhard Knothe replaced ruthenium with iridium as the primary catalyst in a six-step procedure they designed and received a patent in. November.
In laboratory scale experiments, use of the high oleic soybean oil approach produced jet fuel formulations containing 8 to 35 percent aromatics, a range compatible with conventional jet fuels and beyond what ruthenium-based methods can achieve.
The advance, which the team recently reported in an online issue of the International Journal of Sustainable Engineering, opens the door to an increased mix of biofuels and conventional jet fuels as an emission reduction measure. The process also generates little or no naphthalene, a component of jet fuel that emits soot during combustion.
Researchers are now looking for an industrial partner to expand the process and further assess its commercial potential.
Their research also supports a broader effort at the ARS Center in Peoria to develop new, value-added uses for agricultural products or their waste by-products, as well as to create new, sustainable methods of processing them. Ideally, for example, the iridium used to create soybean jet fuel could be replaced or combined with an earth-abundant catalyst like iron to keep costs down, Doll said.
Oil crops other than soybeans could also be used, including inedible sources such as field dill. “We originally used soybean oil because of its high quality, affordability, and existing refining processes. It’s also a product we’ve always worked with at Peoria, ”added Doll. “But any oil that has high levels of oleic acid would work.”
The efforts of the Peoria team also reflect the United States Department of Agriculture’s participation in the Sustainable Aviation Fuels Grand Challenge along with other federal agencies and stakeholder groups. The challenge is a multi-faceted, whole-of-government commitment to enable the production of 35 billion gallons of sustainable aviation fuel per year by 2050, using “home-grown” and other renewable sources.
The Agricultural Research Service is the principal in-house scientific research organization of the United States Department of Agriculture. On a daily basis, the ARS focuses on solutions to agricultural problems affecting America. Every dollar invested in agricultural research has an economic impact of $ 17.