(556e) Overview of Issues Around Deconstruction of Lignin

There is widespread interest in the development of large-scale, economically competitive biorefineries that combine integrated catalytic, thermal, and biological conversion processes to efficiently utilize all of the materials and energy contained in biomass. In commercial large-scale biorefineries, stringent requirements for process performance and profit/cost metrics will have to be met. However, utilizing biomass-derived carbohydrates for bioethanol production generates similar amounts of lignin as a by-product which is either discarded or burned to recover low-grade heat. To improve the economic competitiveness and reduce the environmental footprint of such biorefineries, technologies are needed that utilize both carbohydrate and lignin fractions of biomass and that ultimately improve biomass-based product yields and selectivities. Simply stated, this implies obtaining greater value from lignin. Successful research and development activities for catalytic lignin deconstruction will require three-dimensions of integrated understanding: (1) catalyst design and characterization, (2) reaction and process engineering, and (3) lignin biosynthesis, structure, extraction, chemistry, and characterization. Often in lignin catalysis, well-designed catalysts are effective on certain model compounds that represent lignin dimers (usually β-O-4 dimer), but fail to be effective on real lignin To solve such issues, research must rely on a deep expertise in (1) characterizing biomass and lignin, (2) building accurate (more complex dimers, oligomers, and polymer systems) lignin models, (3) applying methodologies to resolve the complex mixtures that tend to result from lignin deconstruction, and (4) conducting operando characterization of high temperature and pressure reaction condition. I will present an overview on the issues concerning the deconstruction of lignin with a particular focus on reductive methods for the selective disassembly of lignin with heterogeneous catalysts and hydrogen.