Using chemical catalysis to select and diversify biological-derived intermediates

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Lin, Hsi-Hsin
Major Professor
Shanks, Brent H.
Kraus, George A
Tessonnier, Jean-Philippe
Roling, Luke T
Li, Wenzhen
Committee Member
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Chemical and Biological Engineering
Technology development for biorenewables fuel and chemical production is a critical direction. To effectively produce chemicals from biomass feedstock, strategies to convert complex lignocellulose structures to downstream products are required. In this work, we studied the conversion route designs from different viewpoints. Firstly, examining the reaction selectivity among multiple reactions to produce novel chemicals. Secondly, comparing overall process efficiency in different routes to determine the most reasonable intermediate. Finally, determined critical issues for reactions between high potential molecules. In the first chapter, strategies for producing fuels and chemicals from biomass were discussed. To achieve high atom and eco-efficiency for chemical production, the integration of chemical and biological catalysis has received more attention recently. Bio-derived platform molecules that can be converted to various commercial chemicals and novel molecules were proposed. The potential of terpene and terpenoids has been highlighted. However, more studies are required to determine the route feasibility of producing novel molecules and select the platform molecules to reach higher overall process efficiency. In the second chapter, we conducted ammonolysis reactions on saturated and unsaturated C4 esters to test the side reactions for converting platform molecules into downstream products. The conjugate addition has been determined as the primary side reaction for unsaturated esters ammonolysis. Reaction temperatures and base concentration in the solution were determined as critical factors to affect the reaction rate and selectivity. The yield was increased from 67.1 % to 90.6 % at 10 oC with 2.1 M ammonium acetate. In the third chapter, we compared the overall route of p-cymene production via limonene and 1,8-cineole to demonstrate the strategy of integrating biological and chemical catalysis. Dehydrogenation of limonene and 1,8-cineole were conducted in a fixed-bed reactor at 250 oC. Hydrogenation metals such as Cu, Ni, Pd, and Pt also showed significant reactivity to convert terpene into p-cymene. These hydrogenation metals supported on acidic oxide can conduct the additional dehydration step for 1,8-cineole in one reactor. The biosynthetic process of 1,8-cineole can reach a higher titer than limonene owing to lower toxicity. Considering that the extra dehydration step for the 1,8-cineole conversion is facile, the route via 1,8-cineole can be more efficient than via limonene. In the fourth chapter, the influence of water on limonene epoxidation has been discussed. Experiments were performed in an ethyl acetate system with a γ-Al2O3 catalyst. Results showed that the water could reduce the reactivity under the same amount of H2O2, but the intrinsic selectivity remained similar. A more detailed correlation between the reactivity and the H2O2/H2O ratio was discussed. In the end, the reactions were compared with a Dean-Stark apparatus and a regular reflux condenser. The results showed that a Dean-Stark trap could achieve a higher H2O2/H2O ratio and limonene conversion rate under the same initial conditions. Overall, water can significantly reduce reactivity in limonene epoxidation has been concluded. Finally, the conclusions were summarized in the fifth chapter and future directions were suggested in the sixth chapter.
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