Production of Aviation Biofuels

Research Sponsored By: Federal Aviation Administration (FAA)
Principal Investigator: Richard Gustafson
Project Description
Aviation fuel is a complex mixture with stringent end-use requirements. The fuel must have sufficient energy content (enhanced by cycloalkanes), low gelation point (enabled by a narrow molecular weight distribution), and proper lubricity (made possible by aromatic compounds). Currently, biofuels must be blended with petroleum fuels to meet these requirements. New processes are required to produce a 100% biomass based aviation fuel that can be used in existing engines and that can meet carbon emission requirements established by the RFS2.

Current processes to create hydrocarbons from biomass cannot produce the correct mixtures of molecules needed for aviation fuel because lignin and carbohydrates require different processing conditions. Fractionation of biomass into lignin and carbohydrate components, converting them into the needed molecules, and then blending the final products in the correct proportions is the only way to produce a 100% biomass based jet fuel with the required properties.

We will develop an innovative process that combines biomass fractionation, followed by separate carbohydrate and lignin conversion to hydrocarbons with final blending to produce a 100% biomass based aviation fuel. Biomass will be fractionated by steam pretreatment followed by enzymatic hydrolysis. Sugars may be recovered directly or fermented to ethanol which can then be separated from the lignin. The lignin will then be depolymerized to insoluble lignin-derived fragments that are well suited for further conversion to hydrocarbons. The result will be three distinct feedstocks that can be chemically converted separately and optimally to the hydrocarbons needed for jet fuel.

Conversion of lignin fragments, sugars, and alcohols to hydrocarbons will be accomplished by thermal/catalytic processes. Catalytic fast pyrolysis and hydrogenation can be used to convert lignin into naphtenes; high-energy molecules that constitute 40 % of jet fuels. We will catalytically convert sugars and alcohols into olefins and aromatic hydrocarbons using dehydration and oligomerization as well as zeolite upgrading. These processes together generate the molecules that serve as building blocks for a 100 % biomass based aviation fuel.

Thermal/catalytic conversion will result in relatively homogenous molecular products that must be blended to make the final aviation biofuel. We will develop sensors and a model based control system to carry out the blending.

This research builds on the University of Washington work with ZeaChem to produce jet fuel from cellulosic feedstock. The research will result in a bench scale demonstration of an innovative technology to produce 100% biobased jet fuel. Scale to pilot or commercial scale can happen rapidly because of our ZeaChem connection.