First production of fuel-range liquid hydrocarbons from biological feedstock using the fermentative isobutene pathway
12 May 2015
Global Bioenergies has successfully converted renewable resources first into gaseous isobutene via fermentation, which was then subsequently catalytically oligomerized into a mix of fuel-range liquid hydrocarbons, including iso-octane. In 2014, Global Bioenergies signed a collaboration agreement with Audi on the development of bio-isooctane—a high-performance drop-in biofuel for gasoline engines—derived from bio-isobutene. (Earlier post.)
Gaseous isobutene is one of the main building blocks of the petrochemical industry. Fifteen million tons of isobutene are derived each year from oil, and converted into fuels, plastics and elastomers. Global Bioenergies is developing and scaling up a synthetic biology process to produce isobutene from sugar, cereals, and agricultural or forestry waste instead.
For the first time, a batch of isobutene produced and purified on ARD’s Pomacle-Bazancourt site, located close to Reims in France, has been shipped in pressurized containers to the Fraunhofer Institute on the Leuna refinery platform, close to Leipzig in Germany.
There, the isobutene was oligomerized; this is a basic petrochemical process that has received attention for a number of years in terms of catalyst design and process tuning, with an eye to the oligomerization of light olefins (isobutene and isobutane) in FCC units at refineries.
The resulting product slate contained isooctane (string of two isobutene molecules); isododecane (string of three); isocetane (string of four); as well as longer strings. These compounds are associated with large markets:
Isooctane is the gold standard for gasoline engines, and corresponds to unleaded 100 when used neat.
Isododecane is one of the very few bio-sourced molecules well suited to be blended in jet fuel; its registration as a bio-jet fuel is underway in the US.
Isocetane is a heavier fuel that can be used as an additive for diesel engines.
Longer molecular chains are used in the manufacturing of industrial lubricants.
Industrial fermentation of a gas such as isobutene has numerous advantages, which will translate into a reduced OPEX. We have now successfully aligned our isobutene process with a technology leading to a liquid hydrocarbon mix resembling to light oil. Our target will now be to purify the different components of this mix. Getting high-purity iso-octane is one of the main goals of our alliance with Audi.—Rick Bockrath, Vice President for chemical engineering at Global Bioenergies
Global Bioenergies recently announced the start of the construction in Germany of a 100 tons/year capacity Demo Plant, the last step before large scale commercial exploitation of its isobutene process.