Metal-Organic Framework Adsorbents and Processes for Separation of Biomass-Derived Furanic Molecules
Chiang, Ya Dong
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Furanics are important “platform chemical” precursors to polymers, pharmaceuticals, and fine chemicals, and can also be used as biofuels. In the production of 2,5-dimethylfuran (DMF), the catalytic conversion of the biomass feedstock to DMF leads to mixtures of furans diluted in n- butanol (BuOH)., This leads to uneconomically high costs of in distillation-based separation processes, due to the complex composition and formation of azeotropes. This thesis investigates both the fundamental and process engineering aspects of adsorption-based separations that utilize precisely tailored nanoporous materials as separating agents to enable the separation of furans from BuOH. In particular, this thesis investigates the separation mechanism by tuning the hydrophobicity and selective organophilicity of metal-organic framework (MOFs) materials. MOFs are a group of newly explored nanoporous materials consisting of metal ions/clusters coordinated to organic linker molecules. Two classes of MOFs (i.e., UiO and ZIF) are identified as potential adsorbents with high selectivity, capacity, and reusability based upon their structural properties. The results indicate that hydrophilic defect-engineered UiO-66 adsorbents exhibit excellent adsorption selectivities to remove BuOH and enrich DMF to 99+%. In contrast, the intrinsically hydrophobic ZIF-8 adsorbent shows the ability to separate DMF from mixtures that are furan-diluted and compositional-complex. Through detailed multicomponent adsorption experiments, modeling, and techno-economic analysis, novel separation designs that utilize the ZIF-8 adsorbent in simulated-moving bed adsorption processes show significant process economy advantages over distillation-based processes, primarily due to a large reduction in process energy demand.