From sugar to plastic wrap more easily
Like crude oil, basic sugars contain the building blocks for plastics and fuels, but the development of a conversion process for these renewable ingredients has faced stumbling blocks. New research, published in the June 15 issue of Science (2007, 316, 1597–1600), may remove those barriers by perfecting a transition step in the transformation process that produces 5-hydroxymethylfurfural, better known as HMF.
Made from petrochemicals, HMF is used in large quantities to create plastics and so-called fine chemicals, which are used in various specialty products. Now, Z. Conrad Zhang and colleagues at Pacific Northwest National Laboratory (PNNL) have found a way to use glucose and fructose to make HMF, which can then be used to produce anything from paints to biofuels. These two simple sugars could be harvested from plant cellulose or sugar beets, for example, and could serve as potential feedstocks that are much more sustainable than petrochemicals.
The scientists report that they have cleared a major hurdle by using metal halides such as CrCl2 in an ionic-liquid solvent to catalyze and then preserve the HMF produced from glucose and fructose. Their result comes through an unusual catalytic behavior: metal halides actually stabilized HMF once it had formed at catalytic concentrations, instead of enhancing further chemical reactions of the sugar feedstocks.
The team found that CrCl2 as a catalyst with glucose produced HMF at yields approaching 70%. That high recovery rate could help push down costs, which have limited the use of biomass-based sugar stocks for industrial production of HMF. Current methods use acid catalysts to convert fructose or glucose, but the side reactions and byproducts for each sugar lead to problems with purification—and ultimately increase production costs. The PNNL team now intends to work on ways to make purer products.
In related news, another group has recently taken HMF a step further, converting it to a potential transportation fuel.
