An alternative approach to breaking down cellulose and hemicellulose molecules in corn stover biomass could cost less and expand possible end uses beyond cellulosic ethanol, according to new research.
An operation like Poet-DSM’s Emmetsburg, IA, cellulosic ethanol plant breaks down biomass in water, using an acid process followed by an enzyme process. That’s needed because the chemistry to convert the stover’s cellulose, hemicellulose and lignin is different, says Brent Shanks, director of the National Science Foundation’s Center for Biorenewable Chemicals. “Most commonly, people break down the hemicellulose first, then the cellulose.”
That’s an expensive, multi-step process, he explains. “Instead, the trick is to break down the cellulose and hemicellulose together. The solvent has to be relatively inexpensive, relatively robust (to withstand the process) and easily recovered so it can be re-used.”
James Dumesic’s research group at the University of Wisconsin reports initial success with just such a recipe for streamlining cellulose and hemicellulose conversion with a single solvent, gamma-valerolactone, which can be made in the breakdown process.
While results so far show high yields, Dumesic emphasizes that the research is preliminary and not yet ready to scale up outside the lab.
“We believe it would work with other biomass feedstocks and could scale up to a continuous-flow reactor. But it’s going to take time. We’re not going to make this next year.”
A successful scale-up could open the door for converting biomass-based cellulose into levulinic acid and hemicellulose into furfural, two commercially important organic chemicals.
The U.S. uses about 300,000 tons/year of furfural as a solvent and ingredient in adhesives and polymers. It can be further converted to levulinic acid for use in nylon-like polymers, synthetic rubbers, plastics or chemicals, including biofuels.