A new process for converting sugar into diesel fuel and feedstock chemicals for the manufacture of plastics, drugs, and other products, could help industry circumvent the problem of rising oil and natural gas prices.

James Dumesic, of the University of Wisconsin-Madison has demonstrated how to make hydroxymethylfurfural (HMF) from the fruit sugar fructose using a straightforward acid-assisted dehydration process. Two additives reduce the formation of side products while butan-2-ol helps push the HMF into the non-aqueous phase ready for extraction. Yields are 80% of HMF with 90% fructose conversion. The HMF product can be used as an intermediate in polymer production and as a diesel-fuel additive, or even as biodiesel itself. Until now, the high cost of HMF has precluded its widespread use.

"Trying to understand how to use catalytic processes to make chemicals and fuel from biomass is a growing area," explains Dumesic. "Instead of using the ancient solar energy locked up in fossil fuels, we are trying to take advantage of the carbon dioxide and modern solar energy that crop plants pick up."

Other researchers have developed fructose to HMF conversion processes but Dumesic's approach balances pressure, temperature, and reactor design for much higher efficiency and uses a solvent extraction process to separate the product from the reaction mixture effectively once the reaction is complete. Dumesic reckons HMF made from sugar has just the same environmental benefits as biodiesel made from fats, such as used cooking oil, with the added bonus of being a useful chemical feedstock for manufacturing too.

Team member Yuriy Roman-Leshkov, a graduate student working with Dumesic, explains the environmental advantages of the sugar to HMF process. "The nice thing about using biomass as a replacement for all these petroleum products is that it is greenhouse-neutral," he explains, "because it does not introduce additional carbon dioxide into the atmosphere."

Fellow researcher Juben Chheda sees the work as part of an explosion of interest in finding alternative sources for petroleum-based chemicals. "We need to develop new process technologies, and HMF is a building block that can replace products like poly(ethylene terephthalate), a plastic used for soda bottles," he adds. "This is a first step for a range of chemical products that can be obtained from biomass resources, replacing those that come from petroleum sources." The conversion process might be adapted to converting other sugars.

Science, 2006, 312, 1933-1937; http://dx.doi.org/10.1126/science.1126337

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