Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Civil and Environmental Engineering | en_US |
| dc.contributor.advisor | Leu, Shao-yuan Ben (CEE) | en_US |
| dc.creator | Guan, Jianyu | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/14488 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Novel pretreatment control and analytical technique maximizing monolignols yield from waste lignocellulosic biomass | en_US |
| dcterms.abstract | Economic growth has been driven by fossil fuels and petroleum-based chemicals, yet their continued use has heightened global concerns over climate instability and resource depletion. Lignocellulosic biomass offers a renewable and carbon-neutral alternative, but its efficient utilization has been hindered by its recalcitrance due to the compact and cross-linked architecture of cellulose, hemicellulose, and lignin. This dissertation addresses innovative solutions to overcome these challenges; by elucidating biomass molecular structures using the stat-of-the-art techniques, building novel numerical tools in predicting pretreatment performance, and establishing robust conversion processes for lignin valorization. Lignocellulosic structure with significant diversity among plant species was systematically reviewed, classifying hardwoods, softwoods, grasses, barks, and seeds, and correlating their structural features with recalcitrance. Biorefinery strategies were compared, emphasizing pretreatment approaches and their efficiencies in polysaccharide and lignin utilization. Based on comprehensive experimental studies and sample analyses, a novel index, Pretreatment Depolymerization Factor (PDF), was constructed through acid-organosolv pretreatments of Camellia oleifera shell. The model quantified the hydrolysis kinetics for different Xylan conformations, providing the mechanistic foundation with 91% accuracy. Finally, 2D-HSQC SS-NMR and hydrogenolysis experiments identified Cγ-OH initiated Cβ-Cγ cleavage pathway. This mechanism was incorporated into the PDF simulation to quantitatively clarify its treatment of lignin condensation. As a result, application of the PDF model in semi-continuous biomass pretreatments achieves 40.1 mg g⁻¹ monolignol yield with 95% delignification, nearly three-fold higher than baseline. Finally, ¹³C-labeled plant cell walls were analyzed using solidate-state (SS) NMR method to elucidate biomass molecular architectures. Sequential weak-acid fractionation coupled with advanced SS-NMR reveals covalent lignin-xylan linkages and spatial proximities within secondary cell walls, explaining residual recalcitrance and potential modes of lignin intermolecular connectivity. | en_US |
| dcterms.extent | xiv, 145 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2026 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.accessRights | open access | en_US |
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