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Converting Biomass Feedstocks through Heterogeneous Catalysis: How Compressed Liquid Water Influences Catalytic Activity and Stability Public

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Recent technological advances in process intensity and energy efficiency has motivated the use of biomass as a source of sustainable energy. We evaluated how thermochemical biomass conversion reactions operated in a compressed liquid phase can have many process engineering benefits compared to traditional vapor phase reactions, including reduced energy intensive drying steps, reaction intensification and improved thermal management. These process-engineering benefits are the greatest for organics diluted in water, such as algae, food waste, or fermentation feedstocks. The use of heterogeneous catalysts in compressed liquid phase reactions can further improve the selectivity and activity to form a desired product. This is demonstrated in converting food waste at 300 °C and 20.7 MPa reaction conditions using a heterogeneous metal oxide catalyst, which promoted bio-oil yields. A challenge in developing compressed thermochemical processing of biomass is the limited number of heterogeneous catalysts known to be hydrothermally stable under hot liquid water conditions. Therefore, we evaluated how the thermodynamic state of liquid water can influence framework and acid site stability of zeolites; a class of microporous aluminosilicate catalysts with known steric selectivity and Brønsted acidity. The unique hydrothermal stability of the ZSM-5 zeolite framework provided an opportunity to deconvolute the role of water on catalytic activity and stability using ethanol dehydration as a model chemistry. Our work helps evaluate the use of heterogeneous catalysts for compressed liquid phase processing of biomass feedstocks.

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  • 01/05/2021
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  • etd-042419-150838
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  • 2019
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  • 2019-04-24
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