The major bottleneck in the development of fuels from biomass is a source of

Tag : Aromatics Compounds

James Dumesic's team at the University of Wisconsin-Madison set outto convert simple sugars into hydrocarbons that could be blended tomake vehicle fuels that are identical to the ones we use today.'Petroleum has a high energy density, and not all engines currentlyin use are suitable for conversion to run on ethanol,' Dumesicsays.
The key to the team's approach is to remove most of the oxygenatoms from sugar molecules, while keeping a degree of functionalitywithin the molecules to enable further downstream processing. Theytook aqueous solutions of simple sugars such as glucose andsorbitol and reacted them over a platinum-rhenium catalyst. 'Mostof the oxygen atoms are removed, leaving an oily mixture ofalcohols, ketones, carboxylic acids and some cyclic compounds,'Dumesic says. 'These compounds are monofunctional - they only haveone functional group, which makes them much more adaptable forsubsequent conversion.'
The mixture can then be sent over a variety of zeolite catalysts ina range of sequential reactions. 'These catalysts can put branchesinto molecules, or make aromatics, for example,' says Dumesic. 'Youcan flow the products from one reactor to another, ending up with arange of hydrocarbons that you can blend to make gasoline. They arethe sorts of molecule that a petroleum refiner deals with.'
Sugar source
Dumesic says there is some way to go before the system would becommercially viable. 'We are not there yet, but we are learning therules.' He also recognises that the major bottleneck in thedevelopment of fuels from biomass is a sustainable source of sugarswhich does not displace the production of food. 'There are manypeople looking to make sugars from non-edible cellulose and thatwork needs to continue,' he adds.
Jenny Jones of the University of Leeds, UK, who researches thethermal conversion of biomass for energy, says that the workdemonstrates 'some nice chemistry, and the ability to tunedifferent products from the same feedstock is potentially veryuseful'. As well as transport fuel, the process could also producevaluable chemical feedstock molecules which are currently derivedfrom petrochemicals. However, Jones agrees that to make such anapproach sustainable, it is necessary to find efficient ways ofprocessing lignocellulose - the non-edible bulk of biomass - toobtain the sugar molecules in the first place.
Simon Hadlington
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