金属/稀土介孔分子筛催化解聚木质素的机理研究

This project is proposed to utilize metal/rare earth mesoporous molecular sieve as catalyst, depolymerize lignin in a dioxane/methanol or ethanol system, study the refining mechanism, and the designed method is as follows:①Catalytic depolymerization of lignin is the difficult and key point of high-efficiency biomass conversion ②Sn-mesoporous molecular sieve not only has regular porous channel structure, but also possesses excellent performance as a kind of solid acid catalyst. It coincides with the lignin collecting bond’s properties, and can depolymerize lignin with high efficient as a catalyst carrier. ③Supported rare earth catalyst can enhance the hydrothermal stability of mesoporous molecular sieve, disperse the metal nano-particles, and promote the cleavage of C-C bond; ④Supported metal nanoparticles can inactivate the carbocation in the hydrogen status, thus enhance lignin depolymerization yield. This project is proposed to probe into systematic theoretical analysis and experimental research in several aspects, including the reaction system thermal behavior, surface tension, X-ray absorption fine structure spectrum technology detecting the synthesis of metal/rare earth mesoporous molecular sieve, catalyst structure-activity relationship, inactivation mechanism，and diffuse reflectance infrared fourier-transform spectroscopy(DRIFTS) used in in-situ catalytic processes of lignin depolymerization mechanism, thus establish the theoretical model and reaction system of lignin directional catalytic depolymerization with high efficiency.

本项目拟用采用金属/稀土介孔分子筛为催化剂，在二氧六环/甲醇或乙醇体系下催化解聚木质，详细研究其精制机理，构思如下：①催化解聚木质素是生物质高效转化中的难点和关键点；②Sn-介孔分子筛不但具有规则的孔道结构而且是一种性能优异的固体酸催化剂，吻合了木质素连接键的特征，以其为催化剂载体，能够高效解聚木质素；③负载稀土具有增强介孔分子筛的水热稳定性、分散金属纳米颗粒和断裂C-C键的功能；④负载金属纳米颗粒，在临氢状态下有效的钝化正碳离子，提高木质素解聚产率。项目拟通过对反应体系热行为、表面张力、X射线吸收精细结构（XAFS）谱技术检测金属/稀土介孔分子筛合成、催化剂构效关系、失活机理、漫反射傅立叶变换红外光谱（DRIFTS）技术在原位催化环测试分析木质素催化解聚机理等开展深入系统的理论分析与实验探讨，研究金属/稀土介孔分子筛催化解聚木质素的解聚机理，建立木质素高效定向催化解聚的理论模型和反应体系

木质素的高效解聚是研究生物质资源的重要一环。项目围绕木质素高效解聚的研究目标，开展了如下研究：溶剂体系的研究，催化剂的研究和木质素解聚机理的研究。研究了二氧六环/甲醇和异丙醇/甲酸/水体系分别用于碱木质素和玉米秸秆木质素的解聚；研究了酸碱复配型催化剂、多元金属氧化物型催化剂和高分散型分子筛催化剂，实现了木质素的高效解聚；木质素解聚机理的研究发现，木质纤维素中木质素解聚的过程中羟基肉桂酸片段的生成将是控制单体生成的关键一步，碱木质素解聚过程中Lewis酸和加氢活性位点之间的协同作用对解聚效果的影响很大。本项目执行期间共发表了第一标注论文10篇，第二标注论文2篇，第三标注论文1篇，申请了6项发明专利，培养了3名博士，1名硕士。项目研究结果对实现木质素的高效解聚，进而制备液体燃料和高附加值化学品具有重要的参考意义。