Faster and cheaper ethanol-to-jet fuel on the horizon

New catalyst and microchannel reactors improve efficiency and costs.

A patented process for converting alcohol from renewable or industrial exhaust gases into jet or diesel fuel is being scaled up at the US Department of Energy’s Pacific Northwest National Laboratory with the help of partners from Oregon State University and the carbon recycling experts at LanzaTech.

Two key technologies drive the energy-efficient fuel production units.

A one-step chemical conversion streamlines what is currently a multi-step process. The new PNNL patented catalyst converts biofuel (ethanol) directly into a versatile “platform” chemical called n-butene. A microchannel reactor design further reduces costs while providing a scalable modular processing system.

See how a PNNL patented catalyst combined with a unique microchannel reactor can convert ethanol into a useful chemical with multiple commercial uses, including jet fuel. Photo credit: Video by Eric Francavilla; Animation by Mike Perkins | Pacific Northwest National Laboratory

The new process would provide a more efficient way of converting renewable and waste-derived ethanol into useful chemicals. Currently, n-butene is produced from fossil raw materials through the energy-intensive cracking – or breakdown – of large molecules. The new technology reduces carbon dioxide emissions through the use of renewable or recycled carbon raw materials. Using sustainably sourced n-butene as a starting point, existing processes can further refine the chemical for numerous commercial applications, including diesel and aviation fuels, as well as industrial lubricants.

“Biomass is a challenging source of renewable energy because of its high cost. In addition, the size of the biomass increases the need for smaller, distributed processing facilities, ”said Vanessa Dagle, co-investigator of the first research study published in ACS Catalysis. “We have reduced the complexity and efficiency of the process while lowering the cost of capital. Once modular, scaled processing has been demonstrated, this approach offers a realistic option for localized, distributed power generation. “

Micro-to-macro aircraft fuel

In a leap towards commercialization, PNNL is working with longtime staff at Oregon State University to incorporate the patented chemical conversion process into microchannel reactors built using newly developed 3D printing technology. 3D printing, also called additive manufacturing, enables the research team to create a folded honeycomb from mini-reactors that significantly increases the effective surface-to-volume ratio available for the reaction.

“The ability to use new multi-material additive manufacturing technologies to combine the production of microchannels with large surface area catalyst supports in one process step has the potential to significantly reduce the cost of these reactors,” says Brian Paul, senior researcher at OSU . “We are pleased to be a partner of PNNL and LanzaTech in this project.”

Robert Dagle biomass fuel

Robert Dagle is holding a vial of fuel made from converting biomass. Photo credit: Photo by Andrea Starr | Pacific Northwest National Laboratory

“With recent advances in microchannel manufacturing processes and the associated cost reductions, we believe the time is right to adapt this technology for new commercial bioconversion applications,” said Robert Dagle, co-principal investigator of the research.

Microchannel technology would allow the construction of bioreactors on a commercial scale near agricultural centers where most of the biomass is produced. One of the major barriers to using biomass as a fuel is long distances to be transported to large, centralized production facilities.

“The modular design reduces the time and risk involved in deploying a reactor,” said Robert Dagle. “Modules could be added over time as demand increases. We call this scaling by enumerating. “

One-fourth of the commercial test reactor will be 3D printed using methods developed in collaboration with OSU and operated on the Richland, Washington, PNNL campus.

Micro-channel technology

Micro-channel mini-reactors significantly increase the efficiency of the chemical conversion of biofuels. Image Credit: Photo courtesy Oregon State University

As soon as the test reactor is completed, the PNNL trading partner LanzaTech will supply ethanol for the process. The patented process from LanzaTech converts high-carbon waste and residues from industries such as steel production, oil refining and chemical production, as well as gases that are produced during the gasification of forest and agricultural residues and municipal waste, into ethanol.

The test reactor will consume ethanol per day, which corresponds to up to half a ton of dry biomass. LanzaTech has already scaled the first generation of PNNL technology for the production of jet fuel from ethanol and founded a new company, LanzaJet, to commercialize LanzaJet ™ Alcohol-to-Jet. The current project represents the next step to streamline this process and at the same time offers additional product streams from n-butene.

“PNNL was a strong partner in developing the ethanol-to-jet technology that LanzaTech spin-off LanzaJet is using in several facilities under development,” said Jennifer Holmgren, CEO of LanzaTech. “Ethanol can come from a variety of sustainable sources and is therefore an increasingly important raw material for sustainable aviation fuel. This project holds great promise for an alternative reactor technology that could be beneficial in this important path to decarbonise the aviation sector. “

A process that can be coordinated

Since the first experiments, the team has continued to perfect the process. When ethanol is passed over a solid silver-zirconia-based catalyst supported on silica, it carries out the essential chemical reactions that convert ethanol to either n-butene or, with some modifications to the reaction conditions, to butadiene.

But more importantly, after long-term studies, the catalyst remains stable. In a follow-up study, the research team showed that if the catalyst lost activity, a simple process could be used to regenerate coke – a hard, carbon-based coating that can build up over time. An even more efficient, updated catalyst formulation is used for the scale-up.

“We discovered the concept for this highly active, selective and stable catalyzed system,” says Vanessa Dagle. “By adjusting the pressure and other variables, we can also tune the system to produce either butadiene, a building block for synthetic plastic or rubber, or an n-butene suitable for making jet fuels or products like synthetic lubricants . Since our first discovery, other research institutions have also started to research this new process. ”

In addition to Vanessa Dagle and Robert Dagle, the catalyst development team included PNNL researchers Austin Winkelman, Nicholas Jaegers, Johnny Saavedra-Lopez, Jianzhi Hu, Mark Engelhard, Sneha Akhade, Libor Kovarik, Vassilliki-Alexandra Glezakou, Roger Rousseau and Yong Wang. Lead scientist Susan Habas from the National Renewable Energy Laboratory also contributed. PNNL employees Ward TeGrotenhuis, Richard Zheng and Johnny Saavedra-Lopez contributed to the development of microchannel technology.

Chemical conversation research was supported by the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, as part of the Chemical Catalysis for Bioenergy (ChemCatBio) consortium sponsored by the Bioenergy Technology Office (BETO). ChemCatBio is a research and development consortium led by a DOE national laboratory dedicated to identifying and overcoming the catalytic challenges involved in converting biomass and waste resources into fuels, chemicals and materials. The public-private scale-up partnership is supported by DOE-BETO and the Oregon State University Innovation Research Fund.

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