基于分子裁剪的木质素选择性零氢解聚过程与机理

Lignin is the most abundant aromatic natural polymer on the globe and it is regarded as a promising renewable starting material for value-added biochemical and high quality fuel. However, the poor phenolic monomers selectivity and serious char formation are big challenges because of the simultaneous cleavage of multiple structure units and various chemical bonds in current lignin utilization technologies. Therefore, we propose here a novel and effective catalytic system for lignin selective transfer hydrogenolysis base on the molecular tailoring method after the careful investigation on the difference between lignin structure units and main chemical bonds. This process will be enhanced via the coupling of hydrogen production from solvent and the in situ lignin hydrogenolysis. In which, a selective cleavage of designated structure unit and chemical bonds would be obtained, which results in the promoted selectivity of target chemicals and a significant char elimination. At the same time, the key scientific problems would be resolved. For example, we can get special knowledge on the principle for catalyst design and control, the synergistic effect between the solvent effect and the catalysis, and the cleavage and recombination methods of the lignin characteristic chemical bonds. Furthermore, the pathway and catalytic mechanism for the selective depolymerization would be achieved, as well as the char elimination mechanism. Therefore, this study would be a good technology support and theory reference for future efficient and selective depolymerization of lignin to desired high-valued chemicals.

木质素是自然界中含量最丰富的天然芳香族聚合物。然而，当前木质素解聚过程存在多化学键、多结构单元同时断裂导致特定产物选择性低、过程易结焦等突出技术难点。针对上述问题，本项目拟通过对木质素结构及主要化学键差异性的解析，设计并构建基于分子裁剪技术的木质素零氢解聚催化新体系，利用催化作用下的溶剂制氢与木质素特征化学键氢解过程的原位耦合，强化木质素选择性催化解聚过程，在无外加氢源的条件下实现木质素分子特征结构单元和化学键的选择性断裂、抑制过程结焦并解决相应关键科学问题。获得催化剂的结构调控规律、得到木质素零氢解聚过程中溶剂效应与催化作用之间的协同作用机制，阐释木质素的结构演变规律，揭示其特征化学键的断裂与重组方式，得到木质素选择性催化解聚反应历程、催化机理与过程消炭机制，从而为木质素的高效催化选择性解聚制备高附加值生物化学品与过程消炭体系的设计提供技术支持与理论借鉴。

木质素是自然界中含量最丰富的芳香聚合物。木质素裁剪可显著提高产物的选择性，减少产物后处理，是一类非常有工业应用潜力的木质素综合利用方法。本项目研究通过对木质素主要结构和化学键连接方式差异性的解析，基于化工过程耦合与强化的理念，设计并构筑了系列廉价的CuCl2，ZnO和离子液体以及多级孔分子筛负载金属或金属氧化物等均相和多相催化剂，通过对催化体系和反应介质的调控，实现了惰性氛围中木质素含酯基单元的选择性裁剪制备对香豆酸酯或对羟基苯丙酸酯；以及无外加氢源/低氢压条件下木质素定向转化制备4-乙基苯酚等高附加值化学品的过程，并阐释了催化剂构效关系、溶剂效应和木质素结构演变规律以及木质素催化转化反应动力学行为与反应历程。此外，还以木质素水热解聚为模型反应，研究了木质素焦的形成与生长机制，相关研究成果可为木质素的高值化利用提供技术借鉴和理论参考。.基于上述研究，项目还在Chem, Green Chem., ChemSusChem等本领域权威期刊上发表论文13篇，获得授权中国发明专利7项。培养青年学术骨干2名，博士后2名，博士研究生3名，硕士研究生10名。