Co-solvent system for sugar production from lignocellulosic biomass using biomass derived gamma-valerolactone

A biphasic system of γ-valerolactone (GVL), water, and co-solvent enables facile recovery of lignocellulosic sugars and lignin after biomass deconstruction.

The Science                              

Recovering sugars and lignin from the deconstruction solvent GVL relies on methods that are expensive or may inhibit downstream conversion of sugars to biofuels. A new method examines the use of co-solvents¹ and their impact on sugar yield and economics of biofuel production.²

The Impact

Separation of lignocellulosic biomass components from GVL deconstruction solvent via salt or liquid carbon dioxide is inhibitory to downstream conversion microbes, or cost-prohibitive and a safety hazard, respectively. However, the use of a co-solvent, which renders the GVL system monophasic at reaction temperatures but biphasic at lower temperatures, enables facile recovery of high-yield sugar streams and a substantial portion of the lignin on par with previous methods.

Summary

Biomass deconstruction utilizing the solvent γ-valerolactone (GVL), water, and an acid catalyst is a potentially game-changing approach, providing a number of distinct advantages over traditional deconstruction methods. For example, the GVL method avoids the use of expensive enzymes for biomass hydrolysis, is largely agnostic to biomass type, and is renewable since GVL can be generated from biomass and recycled. Recovery of sugars from the GVL system requires separation into aqueous and organic phases, elicited by the addition of salt or liquid carbon dioxide (CO₂). However, high salt concentrations are inhibitory to bioconversion microbes downstream whereas the high pressures required for liquid CO₂ extraction lead to safety concerns and high capital and operating costs. A recently described alternative method used a variety of co-solvents, which render the GVL system monophasic at reaction temperatures but biphasic at lower temperatures, thus resulting in spontaneous separation of sugar and lignin streams from GVL/co-solvent, a significant advantage over prior recovery methods.¹ A second study examined hypothetical biorefinery configurations and technoeconomic analysis (TEA) for production of ethanol using the GVL system with toluene as a co-solvent.² TEA indicated that the minimum selling price (MSP) of ethanol was reduced to $2.95 per gasoline gallon equivalent (GGE), 12.5% lower than that achieved by the GVL/CO₂ extraction method and 9.7% lower than that of the benchmark enzymatic strategy.

Contacts (BER PM)

N. Kent Peters
Program Manager, Office of Biological and Environmental Research
kent.peters@science.doe.gov, 301-903-5549

(PI Contact)

James Dumesic
University of Wisconsin-Madison
dumesic@engr.wisc.edu

Christos Maravelias
University of Wisconsin-Madison
christos@engr.wisc.edu

Funding

This work was funded by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-FC02-07ER64494).

Publications

¹Motagamwala, A.H. et al. “An engineered solvent system for sugar production from lignocellulosic biomass using biomass derived γ-valerolactone.” Green Chemistry 18, 5756 (2016), DOI:10.1039/c6gc02297a.

²Won, W. et al. “A co-solvent hydrolysis strategy for the production of biofuels: process synthesis and technoeconomic analysis.” Reaction Chemistry and Engineering (2017), DOI:10.1039/c6re00227g.