(226c) Catalytic Conversion of Sugars to Conventional Liquid Fuels

Authors: 
Cortright, R. - Presenter, Virent Energy Systems, Inc.


Current commercial biofuels generation technologies exploit naturally occurring biological pathways which have been optimized through natural selection and genetic engineering to maximize the conversion of sugars into ethanol. However, the presence of oxygen in the molecular structure of ethanol creates substantial disadvantages such as lower volumetric energy value, higher process energy cost associated with dewatering, and infrastructure changes required to ship ethanol to market. Virent Energy Systems has discovered and is now developing innovative and novel catalytic methods that convert plant sugars into non-oxygenated hydrocarbon molecules that have the same volumetric energy value as fossil fuel derived liquid fuels, do not require energy extensive dewatering steps, and can be blended seamlessly to make conventional gasoline, diesel, and jet fuel. These methods utilize Virent's BioForming® technology to produce renewable gasoline, diesel, and jet fuel from a wide range of abundant biomass feedstocks, including non-food varieties. This patented BioForming® platform technology utilizes catalysts and reactor systems similar to those found in standard petroleum oil refineries. Using Virent proprietary catalyst systems, water soluble carbohydrate-derived compounds (e.g. polysaccharides, monosaccharides, polyhydric alcohols, mono-alcohols) are converted into a combination of water, hydrogen, gaseous fuels, and liquid hydrocarbons. The water, fuel gases and any excess hydrogen are easily separated from the liquid hydrocarbon in a simple three-phase separator. The water, fuel gases, and excess hydrogen can be recycled for further use in the system or collected for use in other applications. Depending on the configuration, these catalytic methods can generate a mixture of hydrocarbons with vapor phase characteristics, energy density, and octane ratings that would be applicable as gasoline or a blending mixture for gasoline. Another configuration would allow the generation of non-oxygenated hydrocarbon mixtures with energy density, freezing point characteristics, and vapor pressure characteristics that would allow this mixture to be used as jet fuel. Other process configurations would generate non-oxygenated hydrocarbon mixtures with cetane rating and vapor pressure characteristics that would allow this mixture to be used as diesel fuel.

Virent's novel technology is not limited to any single type of sugar, unlike processes such as fermentation that rely on microorganisms and enzymes. By selecting different catalysts and processing conditions, various types of sugars, including mixed sugar streams and polysaccharides, can be reliably converted into the desired non-oxygenated hydrocarbon fuels. Potential carbohydrate feedstocks include: sucrose (from sugar cane or sugar beets); corn sugar (glucose from conversion of corn starch); sugars derived from hydrolysis of hemicellulose and cellulose (including polysaccharides, organic acids, and furfural byproducts); and water soluble oxygenated compounds such as diols, glycerol, and sugar alcohols. With this capability, the BioForming® process can also utilize the lowest cost biomass sources available in each location and supply more energy without reducing the available food supply. Preliminary economic analysis suggests that converting sugars to conventional liquid fuels with these catalytic methods can economically compete with petroleum fuels at crude oil prices greater than $60/bbl.