Conversion of sugars into hydrocarbons for blending into jet and diesel fuels: general considerations

To transform biomass into components compatible with hydrocarbon fuels it is clear there are two main transformations that need to occur, deoxygenation and carbon chain extension.  Deoxygenation is necessary to increase energy content and to compatibilize the components with existing petroleum-derived fuels.  Chain extension is needed to convert intermediates derived from biomass, such as five and six carbon sugars, into components with the correct boiling range for blending with specific fuels.  Through these transformations it becomes possible to produce drop-in fuels that are transparent to the consumer, have unlimited blendability, and can utilize existing infrastructure for storage and transportation. 

The development of transformation routes that efficiently convert biomass-derived intermediates into products that are compatible with the existing fuel infrastructure, which fit within the specifications for gasoline, jet and diesel fuels, is currently an area of intense research interest.  The potential routes for decreasing the oxygen content of biomass intermediates include decarboxylation, dehydration, and hydrodeoxygenation.  Rejection of oxygen as carbon dioxide, decarboxylation, results in significant carbon and mass loss from sugars, while rejection of oxygen as water, dehydration, leads to unsaturated products and undesirable tars.  Hydrodeoxygenation, using hydrogen to remove oxygen as water, produces saturated products and retains carbon, however, uses expensive hydrogen, catalysts and often severe conditions.  This presentation will discuss the difficulties in converting sugars to hydrocarbons and compare the different routes using practical examples to highlight the impact of choosing one route over another.