木质素解聚制备含氧芳香化合物的氧化-水解策略研究

Lignin is a natural polymer full of aromatics and oxygen-containing structures. It is significant to depolymerize lignin into oxygen-containing aromatics for both high efficient utilization of the renewable biomass and substitution of the fossil resources. In this project, we are going to study the selective activation and cleavage of the lignin ether bond and adjust the hydrogen bond strength. An oxidation-hydrolysis strategy will be developed for the lignin depolymerization to oxygen-containing aromatics. The transformation of ether bond to ester bond will be achieved by the oxidative cleavage of Cβ–Cγ bond. We will also endeavor to study the key influential parameters which lead to the selective activation of Cβ–Cγ bond. The kind and structure of hydrogen bond, and adjusting of hydrogen bonds strength will also be investigated. An organic-metal hybrid catalyst will be design to simultaneously realize the hydrogen bond weakening, Cβ–Cγ bond activation and cleavage, thus achieving the conversion of ether bond to ester bond for the real lignin. We will explore the mechanism of cooperatively catalytic activation and cleavage of Cβ–Cγ bond. We believe that our study will greatly contribute to the basic understanding of lignin conversion to chemicals.

木质素富含氧和芳香环，利用木质素制备含氧芳香化合物对于可再生资源的高效利用及化石资源的替代具有重要意义。本项目紧密围绕木质素β–O–4主要连接结构中醚氧键的活化和选择断键及其分子氢键的调节等关键科学问题，提出一种氧化-水解的新断键策略，解聚木质素制备芳香羧酸化合物。研究通过选择性氧化裂解Cβ–Cγ键来实现木质素醚氧键转变成酯键过程。探索催化剂对Cβ–Cγ键的选择活化规律；研究氢键的类型和结构、探索调节木质素氢键强弱的途径和方法；设计一种有机-金属杂化催化材料，构建针对氢键削弱、Cβ–Cγ键氧化裂解的协同活化的催化环境，研究原生木质素醚氧键转变成酯键过程。通过实验与理论计算结合，研究多中心协同活化与断裂Cβ–Cγ键，从分子层面上认识切断Cβ–Cγ键微观机理。通过该项目的实施，为木质素的转化提供技术基础和科学依据。

本项目围绕C–C/C–O键选择性裂解关键问题，以β-O-4模型和甘油化合物为探针分子，研究了C–C/C–O键裂解规律，发展了C–C/C–O键裂解催化体系，阐明了其裂解机理。制备了一种Pd-PdO/TiO2催化剂，Pd为脱氢位点，PdO活化Cβ–O键，双组分协同实现CαH–OH中氢定向转移氢解Cβ–O键，实现了木质素无氢解聚。制备了Au/CdS光催化剂，实现了木质素单体光催化脱氢偶联，发展木质素油偶联-加氢制高碳烷烃新路线。以甘油化合物为探针分子，研究了多元醇C–C键选择性裂解的方法；发展了光催化C-C键裂解方法，实现了生物质多元醇常温下C–C键裂解到甲醇、合成气新过程；提出了氧空位介导催化的概念，耦合C–C键氧化裂解和加氢反应，实现了木质纤维素低温甲烷化过程(≤200 °C)。以木质素磺酸钠为碳源前驱体，发展了S-Ni@C电催化剂制备方法。