Coupling Chemical and Biological Catalysis to Produce Biorenewable Chemicals.

摘要

Recent advances in metabolic engineering have allowed for the production of a wide array of molecules via biocatalytic routes. The high selectivity of biocatalysis to remove functionality from biomass can be used to produce platform molecules that are suitable for subsequent upgrading over heterogeneous catalysts. Accordingly, the more robust continuous processing allowed by chemical catalysis could be leveraged to upgrade biologically-derived platform molecules to produce direct or functional replacements for petroleum products. This thesis discusses our progress in developing processes that utilize a combination of chemical and biological catalysis, and using the perspective of heterogeneous chemical catalysis we identify and address challenges associated with bridging the gap between the two catalytic approaches.;Chapter 3 and Chapter 4 focus on the development of new chemistry that utilizes bio-catalytically-derived platform molecules to yield high-value biorenewable chemicals. In Chapter 3 we show that furylglycolic acid (FA), a pseudo-aromatic hydroxy-acid suitable for co-polymerization with lactic acid, can be produced from glucose via enzymatically derived cortalcerone using a combination of Bronsted and Lewis acid catalysts. Cortalcerone is first converted to furylglyoxal hydrate (FH) over a Bronsted acid site, and FH is subsequently converted to FA over a Lewis acid site. In Chapter 4, Triacetic acid lactone is demonstrated to be a versatile biorenewable molecule with potential as a platform chemical for the production of commercially valuable bifunctional chemical intermediates and end products, such as sorbic acid. In Chapter 8 we extend this chemistry to the upgrading of 4-hydroxycoumarin to produce high-value pharmaceutical building blocks.;Chapter 5 demonstrates that supported Ni, Pt, and Pd catalysts used for liquid phase hydrogenation are inhibited by the biogenic impurities present in biologically-derived feedstocks used to produce high-value chemicals. This inhibition is addressed in Chapter 6, where we show that microenvironments formed around catalytic active sites mitigate catalyst deactivation by biogenic impurities present during production of biorenewable chemicals from biologically-derived species. Finally, in Chapter 7, we use transition state theory as applied to thermodynamically non-ideal systems to explore the origins of the improved stability and activity that we observed in Chapter 6. We conclude with a discussion of future directions.