原生木质素的分离和转化效率决定着生物质整体利用的经济性和可持续性，将其同步氧化分离并转化为小分子有机酸是一条相对绿色且简洁的思路，但如何抑制氧化分离过程中惰性碳碳键缩合和深度氧化为二氧化碳途径是难点。基于“lignin-first”策略和固体碱活性氧蒸煮技术，本项目拟在镁碱催化的可控微碱环境中将原生木质素定向氧化为小分子有机酸。首先通过对镁碱的设计、合成、表征和筛选，明确催化剂制备条件与其形貌、组成、碱位点类型以及碱强度关系；接着通过表征反应过程中木质素结构变化，分析小分子降解产物分布与演变规律，解析具有典型结构的木质素模型分子断键机制，进而把握镁碱特性与木质素结构以及反应选择性之间的联动关系；最后结合理论模拟计算与动力学模型，阐明镁碱催化对惰性缩合和深度氧化反应途径的抑制机制，探索催化剂再设计和反应体系调控方法，以期提高原生木质素氧化分离转化选择性，为木质素优先利用提供思路和理论参考。

The feasibility of fractionation and valorization of protolignin in lignocellulosic biomass determines the economy and sustainability of the overall utilization of biomass. Simultaneous separation and degradation of protolignin to low-molecular-weight organic acids such as formic acid and acetic acid by oxidation is a green and facile process design. But this process is hindered by serious side reactions; for instance, inert carbon-carbon bond condensation and deep oxidation to low-value carbon dioxide. According to the lignin-first strategy and the technique of cooking with active oxygen and solid alkali (CAOSA), a novel process for the selective oxidation of protolignin into low-molecular-weight organic acids is developed for which the proposed Magnesium-based catalysts can supply the reaction system with a regulated micro-alkaline environment. Initially, the Magnesium-based catalysts will be designed, prepared, characterized and screened to reveal the correlation between various preparation conditions of catalysts and their surface morphologies, chemical compositions, alkali site types and strength. Subsequently, interactions between degradation products selectivity and properties of Magnesium-based catalyst as well as structures of protolignin are going to be elucidated by monitoring structural changes of lignin during delignification process, investigating the distribution and evolution of products, and analyzing breaking mechanism of bonds for model molecules with a simplified lignin structure. Eventually, on the basis of the calculation of theoretical simulation and the kinetic models, the mechanism of Magnesium-based catalyst to inhibit inert condensation and deep oxidation pathways will be proposed. The following catalyst redesigning and reaction system regulating will be explored to optimize the selectivity of oxidative protolignin separation. The present study can potentially provide the theoretical references for the lignin-first approach to full utilization of lignocellulosic biomass.