While much attention has focused on the use of biomass to produce ethanol, high capacity processes are required for the production of hydrocarbon fuels and chemicals from lignocellulosic biomass. This follows from the fact that relative to crude petroleum, ethanol is of limited use in chemical manufacturing and has lower energy density. Furthermore, the development of biological pathways for the conversion of cellulosic biomass to fuels will result in the generation of huge quantities of lignin residues.
Lignin is also of interest as a feedstock due to the fact that it is more energy-dense than cellulose or hemicellulose. Hence, if efficient methods can be found for lignin deconstruction, a new paradigm would be created, i.e., that of biofuels production from (engineered) lignin-rich plants. However, the utilization of lignin as a resource for the production of biofuels is presently hampered by its resistance to chemical and biological manipulation, and consequently, by a lack of selective and cost-efficient processes for its conversion to fuels and chemicals. The overarching goal of this work is the development of new processes for the direct conversion of lignin to liquid fuels, based on a sound understanding of the chemistry of lignin deconstruction.
Our concept for the utilization of lignin is based on a two-fold approach:
i) Critical properties are being designed into plant cells in order to facilitate the downstream processing of lignin - implementing drivers of evolution that are totally different from those in natural systems. This involves the utilization of research tools for chemical biology combined with directed molecular engineering of critical crop properties; specifically, lignin composition is being targeted, with the aim of optimizing plant metabolism and identifying chemical probes and engineering strategies that stimulate maximal interunit linkages among lignin structures that are most readily cleaved.
ii) The deconstruction of lignin is being studied at the molecular level, to guide both the foregoing lignin engineering activity and the development of improved processes for lignin utilization. These studies will help to shed light on the chemistry involved in the thermal and chemical deconstruction of the important but poorly studied ?-5 linkage in lignin, as well as revealing how critical bonds in lignin can be cleaved in low temperature oxidative processes. In initial work, a series of compounds have been synthesized which model the main interunit linkages in lignin. Using these compounds, solvents and catalysts are being screened which facilitate the oxidative cleavage of these units.
- Funding Agency: National Science Foundation's office of Emerging Frontiers in Research and Innovation (EFRI)
- Dates: 2009-2013 (4 year project)
- Participants: University of Kentucky's Center for Applied Energy Research; Department of Chemistry; Department of Horticulture