木质素解聚与缩合调控的分子机制

Lignin is the most abundant resource of aromatic compound in nature; its valorization plays a crucial role in lignocellulosic biorefinery. Lignin stubborn structure and condensation phenomenon during lignin depolymerization are common key technologies, and hamper the process of lignin volarization and the next generation biorefinery. So, the molecular mechanism of regulating lignin depolymerization and re-aggregation has become a worldwide problem, which has not been marked clearly so far. To meet the above-mentioned scientific issue, we, for the first time, intend to explore a novel technology on gamma photoelectron oxidation/formic acid induced degradation of lignin from molecular scale level. The primary objective of this project is to clarify the mechanism and effects of transient species (such as free radicals) derived from gamma oxidation biomass. Furthermore, it is also elucidated the degradation pathway of lignin into low-molecule-mass aromatics suitable for downstream processing so that the condensation of lignin was inhibited. Firstly, using lignin model compound as feedstock, we investigate the effect of gamma photoelectron oxidation on the structural active groups of lignin in order to inhibit the condensation reaction during lignin degradation; Secondly, to explain the regulation mechanism of lignin depolymerization and re-aggregation, we further study the effect of transient species (such as free radicals) produced from the gamma photoelectron oxidation on the products features of lignin degradation; Finally, using actual biomass as raw material, we explore the pathway of low–molecular-mass compounds resulted from the gamma ray oxidation /formic acid induced degradation of biomass. Therefore, the findings of this proposal are useful to provide the scientific theory foundation and technology support for lignocellulosic biorefinery in the future.

调控木质素解聚并抑制小分子片段缩合重聚，已成为木质素高效利用和新一代生物炼制的共性关键问题，极具挑战性。至今，木质素解聚与缩合调控的分子机制并不清楚。针对上述科学问题，本项目提出γ光电子氧化-甲酸诱导降解木质素新技术，从分子水平阐明γ光电子氧化自由基形成规律与作用方式，剖析木质素高效降解途径，诠释甲酸阻止小分子片段发生缩合重聚的调控机制。首先，以木质素模式化合物为对象，研究γ光电子氧化-甲酸诱导降解木质素结构β-O-4键的断裂规律，揭示木质素结构碳正离子和亲电受体的[HCOO]-保护机理，抑制分子内C-C键歧化反应发生；其次，研究γ光电子氧化-甲酸诱导降解木质素的反应活化能与降解产物特征，探明木质素解聚限速步骤和缩合重聚的调控策略；最后，以实际生物质为对象，研究γ光电子氧化-甲酸诱导降解生物质目标产物流向，构筑γ光电子氧化-甲酸诱导降解木质素的新技术体系，为木质纤维素生物炼制奠定理论基础。

项目执行情况按照任务书内容有计划、有步骤地进行，总体执行情况良好。自2018年立项以来，完成了任务书规定的研究内容，取得了预期研究目标。研究工作方面，本项目提出了γ光电子高能氧化-甲酸诱导降解木质素新技术，从分子水平上，阐明γ光电子氧化瞬态物种形成规律及其作用方式，构建木质素高效降解途径，诠释木质素解聚和抑制缩合反应的调控机制。在此基础上，建立了高物料装载量（生物质固含量为25-40 wt.%）的γ光电子氧化-甲酸诱导降解木质素的同时，实现了生物质组分的原位分级分离新技术，为新一代生物炼制奠定科学理论基础和提供技术支撑。此外，依托该基金项目资助，我们还进一步研究了分离木质素和纤维素用于生物基衍生催化剂的制备技术。人才培养方面，已培养副高级人才1人（2021年陈毅明评为高级实验员），博士毕业生1名（周华博士毕业后，进入清华大学博士后工作站），在读博士生1名（展旺在西安交通大学攻读博士生），硕士毕业生4名。论文发表方面，目前标注项目编号已发表科研论文13篇。专利申请方面，已获授权国家发明专利1件。经费支出合理，截止2021年12月，直接经费已支出560113.93元，占比89.60%，尚结余直接经费79886.07元，占比10.40%。