Green chemistry, biorefineries and second generation biofuels

Things are speeding up. Yesterday's announcement that researchers at the University of Wisconsin-Madison have developed an efficient process to make a chemical intermediate called HMF (hydroxymethylfurfural) from fructose from biomass, is entirely in the line of the integrated vision on biofuels and biomaterials, which we and our friends report about.
These petroleum-free polymers show that it is becoming increasingly likely that almost all products from the petro-chemical industry, will find a green counterpart based on sugars and oleogeanous biomass.

The researchers:

The new process goes beyond making fuel from plants to make industrial chemicals from plants...Dumesic's research group made a series of improvements that raised the HMF output, and also made the HMF easier to extract.

Once made, HMF is fairly easy to convert into plastics or diesel fuel. Although the biodiesel that has made headlines lately is made from a fat (even used cooking oil), not a sugar, both processes have similar environmental and economic benefits, Dumesic says. Instead of buying petroleum from abroad, the raw material would come from domestic agriculture. Expanding the source of raw material should also depress the price of petroleum.

The idea itself is not new, and in fact, Madison has long been a hotbed for research into biomass conversion for kicking the petroleum habit. Professor James Dumesic and his team, however, have broken new ground in terms of creating a process that can compete economically with the more conventional and unsustainable models.

Trying to understand how to use catalytic processes to make chemicals and fuel from biomass is a growing area. 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.

HMF can be converted into plastics, petroleum or diesel fuel extenders, or even into diesel fuel itself. The two-phase process operates at high fructose concentrations (10 to 50 wt.%), achieves high yields (80% HMF selectivity at 90% fructose conversion), and delivers HMF in a separation-friendly solvent.

Prof. James Dumesic—a co-founder of Virent, a company which is commercializing the aqueous phase reforming technology he developed (earlier post)—and his research team reports on this work in the 30 June issue of the journal Science.

The basic approach to this type of biofuel technology is the controlled removal of oxygen from carbohydrates to obtain oxygenated hydrocarbons. The controlled elimination of water from sugars has been studied extensively, and can provide HMF, levulinic acid, and other organic acids.

Although other researchers have previously converted fructose into HMF, Dumesic’s research group made a series of improvements that raised the HMF output and also made the HMF easier to extract.

The new process first dehydrates the fructose in the aqueous phase with the use of an acid catalyst (hydrochloric acid or an acidic ion-exchange resin) with dimethylsulfoxide and/or poly(1-vinyl-2-pyrrolidinone) added to suppress undesired side reactions.

The HMF product then moves to a solvent that carries it to a separate location, where it is extracted. Once made, HMF can be converted into plastics or diesel fuel.

Dumesic is also exploring methods to convert other sugars and even more complex carbohydrates into HMF and other chemical intermediates. In earlier work, Dumesic and his team had demonstrated the dehydration and hydrogenation of an aqueous stream of sorbitol to hexane.

This field of study is ripe for further rapid advances as the revolution in catalysis, computational modeling, and combinatorial chemistry will lead to a suite of catalytic systems that will facilitate the conversion of biomass polysaccarides to liquid alkanes and oxyalkanes for fuel applications.