|The three stages of the Centia process, with different reforming pathways for different fuels. Click to enlarge.
Diversified Energy Corporation (DEC) has produced a bio-gasoline fuel very similar to traditional unleaded gasoline using its Centia process, licensed from North Carolina State University (NCSU).
Centia is based on a three-step thermal, catalytic, and reforming process that has the potential to turn virtually any lipidic compound—e.g., vegetable oils, oils from animal fat and oils from algae—into 1-for-1 replacements for petroleum jet fuel, diesel, and gasoline. (Earlier post.)
The three steps are:
Hydrolytic conversion. The feedstock is heated under pressure to separate free fatty acids from glycerol in the triglycerides in the feedstock. Centia accomodates any lipidic compound without modification to the production process.
Decarboxylation. The free fatty acids and solvent are heated, pressurized, and passed through a catalyst in a reactor to produce n-alkanes, the building blocks of fuels.
Reforming long-chain alkanes. The resulting alkanes—straight-chain hydrocarbons of 15-17 carbon atoms—are reformed into branched alkanes and ring structures. The process is optimized to maximize C10 through C14 iso-alkanes. The alkanes can be reformed differently to create a variety of fuel types. By varying the catalyst, temperature, pressure, and kinetics of this third step, Centia can produce a wide range of biofuels that mimic their petroleum-derived counterparts.
The bio-gasoline tests were conducted at NCSU using demonstration reactors, operated under temperature and pressure with a proprietary catalyst developed specifically for the Centia bio-gasoline process.
Starting with an input mimicking what would have originated as soybean oil, the process generated a fuel closely resembling the carbon number profile and molecular composition of unleaded gasoline. A mass conversion efficiency in excess of 90% was achieved.
Further development, optimization, and testing activities are being planned, including an end-to-end Centia system demonstration to make bio-gasoline, Jet A-1/JP-8, and renewable diesel. Development work also is continuing on various steps in the process to show that the fundamental chemistry works regardless of renewable oil input source.
In addition to the bio-gasoline work, Centia has completed the construction and demonstration of a glycerol burner that will safely burn the glycerol byproduct from Centia and provide an energy source back into the process. This same burner could make productive use of the crude glycerol generated from traditional transesterification-based biodiesel plants.
Diversified Energy is also the developer of the HydroMax gasification process. (Earlier post.) In December, the US Department of Defense selected Diversified Energy Corporation and Velocys to design a portable synthetic fuel production system based on DEC’s HydroMax gasification technology and Velocys’ advanced Fischer-Tropsch approach. (Earlier post.)