UNIVERSITY OF KENTUCKY

Intellectual Merit: 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 project 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. This will require the integration of bio-engineering, chemistry, catalysis and chemical engineering, with the following specific objectives: i) Critical properties will be 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 will involve the utilization of research tools for chemical biology combined with directed molecular engineering of critical crop properties; specifically, lignin composition will be 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 will be 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. Through this research, improved catalytic processes will be developed for the efficient processing of lignin into fuels, as well as valuable chemicals. Broader Impacts: 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. Lignocellulosic biomass could potentially produce over 60 billion gallons of fuel per year, replacing nearly a third of the gasoline used in the US. However, existing pyrolysis processes for lignin deconstruction require high temperatures, making the overall energy balance less favorable. The proposed research will therefore contribute to the national effort to design efficient, cost-effective processes for utilization of our abundant biomass resources. An additional outcome of this project will be the training of students in key aspects of biofuels design and production. Collaboration between the academic departments involved in the project and the Center for Applied Energy Research will not only allow students to receive traditional graduate and undergraduate education, but will also result in their exposure to a broad range of disciplines in the field of energy research. Emphasis will be placed on giving practical experience in the chemical and engineering aspects of the project to those working on plant design and manipulation, and vice versa.

Clarification of Codes