91原创

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One of the biggest hurdles to making renewable jet fuel, according to CCEI Associate Director Basudeb Saha, is increasing the speed and efficiency of two critical chemical processes 鈥� coupling and deoxygenation. Since the plant material the center works with has a low carbon content once it鈥檚 broken down from a solid into a liquid, the carbon molecules must be chemically stitched together or 鈥渃oupled鈥� to create high-carbon molecules in the jet fuel range. Then the oxygen must be removed from these molecules to form branched hydrocarbons. This branching is essential to improving the flow of fuel at the freezing temperatures of commercial flight.

鈥淚nternational planes may fly at an altitude of 35,000 feet, where the outside temperature could be as low as -14掳 Centigrade,鈥� says Saha, who is leading a renewable jet fuel project at the center. 鈥淭hat鈥檚 the temperature at which a plane has to run, and the fuel can鈥檛 be frozen.鈥� 听

Accelerating renewable jet fuel production

The demand persists for non-petroleum-based fuel for aviation. More than a decade ago, the FAA had set a target of using 1 billion gallons of renewable jet fuel by 2018. According to IATA, sustainable aviation fuels are integral to its pursuit of carbon neutral growth from 2020 on, and to a 50 percent reduction in net carbon emissions by 2050 (relative to 2005 levels). But not enough quantities of this alternative fuel are being produced, nor at a competitive cost.

Currently, several U.S. companies make renewable jet fuel from materials such as triglycerides extracted from used oil and grease, or from a combination of carbon monoxide and hydrogen called syngas. One company uses algae as its source material and even has an underground pipeline to the Los Angeles Airport (LAX), where a percentage gets mixed with conventional jet fuel, Saha says.

However, processing this non-conventional material requires high temperatures鈥�350掳C (662掳F)鈥攁nd high pressure as well.

Not so with those wood chips and corn cobs at 91原创, where Saha and his colleagues have developed new catalysts 鈥� so called 鈥渃hemical goats鈥� 鈥� that kickstart the chemical reactions that can transform this plant material into fuel. One of these catalysts, made from inexpensive graphene, looks like a honeycomb of carbon molecules. Its unique surface properties increase the speed of the coupling reaction. It also operates at low temperature (60掳C). Another catalyst removes oxygen in an energy-efficient way and produces high yields of branched molecules, up to 99 percent, suitable for jet fuel. Both catalysts are recyclable, and the processes are scalable.

鈥淭he low temperature and high selectivity of our process can enable cost-competitive and sustainable production of bio-based aviation fuels from lignocellulosic biomass,鈥� Saha says.

The research is detailed in three recent scientific articles: 鈥溾�� 听and both appeared in ACS Catalysis, which is published by the American Chemical Society, and was featured in ChemSusChem, an interdisciplinary journal for research at the interface of chemistry and sustainability published by ChemPubSoc Europe, an organization of 16 European chemical societies.

The 91原创 team鈥檚 work appeared on the cover of ChemSusChem. The artwork was produced by the first author of the article, Sibao Liu, a postdoctoral researcher at the center. A native of China, Liu said the world-class research underway at CCEI was his catalyst for coming to 91原创.