新一类介-微孔分子筛催化裂解木质素定向制备高值化学品反应规律研究

Lignin is an abundant biomass, so it is an important significance of efficient utilization of lignin in view of the shortage of fossil resource. Due to the inherent defects of the traditional catalysts, such as liquid strong acid, microporous molecular sieve and mesoporous molecular sieve, used in the lignin catalytic pyrolysis process, this project will prepare a novel meso-microporous molecular sieve with the good stability and high acid strength by the ionthermal synthesis on the supramolecular self-assembly effect of acidic functional ionic liquid, template of block copolymer from ethylene oxide and propylene oxide, soluble metal salts with the strong acid center, and different silica sources, which would make it have the advantages of both microporous and mesoporous zeolites. Through comparative study, it will be clarified that the essential reason why the acid strength and stability of meso-microporous molecular sieve by the ionthermal synthesis is significantly superior to that of the hydrothermal synthesis. Then the meso-microporous molecular sieve will be used in the catalytic pyrolysis of lignin, and base on the characteristic of the effective regulation in the pore structure and acidity of meso-microporous molecular sieve, the aromatic products will be formed with high selectivity. The relationship of the structure and catalytic property will be revealed, and the kinetics and reaction mechanism will be clarified. This study will provide the theoretical basis for the high value utilization of lignin.

木质素是来源丰富的生物质资源，实现木质素的高值利用对于缓解化石资源短缺危机具有重要意义；本项目针对当前木质素催化裂解过程所用液体强酸、微孔分子筛和介孔分子筛等催化剂的固有缺陷，拟在酸功能离子液体存在的离子热条件下，通过酸功能离子液体、环氧乙烷环氧丙烷嵌段共聚物模板剂、能产生强酸中心的水溶性金属盐及不同硅源之间的自组装作用，创制孔壁具有微孔分子筛晶态结构特征，而孔径为介孔尺寸的新一类杂化材料—高稳强酸介-微孔分子筛，使微孔分子筛与介孔分子筛的优点融为一体；通过对比研究，阐明离子热条件创制的介-微孔分子筛在酸强度和稳定性上显著优于水热条件的本质原因；将高稳强酸介-微孔分子筛用于催化木质素裂解反应过程，依据介-微孔分子筛的酸性和孔结构能有效调控的特性，高选择性制备出芳香基产物；明确介-微孔分子筛的结构与催化性能的相关性，以及新催化反应的动力学规律和反应机制，为木质素的高效转化利用提供理论依据。

木质素是来源丰富的生物质资源，实现木质素的高值利用对于缓解化石资源短缺危机具有重要意义。针对当前木质素催化转化过程所用传统酸性催化剂的固有缺陷，以离子液体为介质创制孔壁具有微孔分子筛晶态结构特征，而孔径为介孔尺寸的新一类高稳强酸介-微孔分子筛，用于催化木质素裂解，以期实现木质素的高效转化。本项目设计合成了15种新型功能化离子液体，运用红外、核磁等技术确定了其结构；以上述新型离子液体为溶剂或结构导向剂，创制了8种新型酸性介-微孔分子筛，通过X-射线粉末衍射、电镜等技术表征了其介-微孔结构。研究发现：离子液体种类、介-微孔分子筛合成条件对介-微孔分子筛的晶态结构、孔尺寸、酸性质等因素均产生显著影响，并直接影响介-微孔分子筛的催化活性和选择性。以离子热合成的介-微孔分子筛为催化剂，木质素的裂解率超过65%，主产物高藜芦酸、高香草酸和愈创木酚占裂解产物总量的85%；在相同反应条件下，以微孔ZSM-5为催化剂，木质素的裂解率为48%，主产物占裂解产物总量的60%；以水热合成的介-微孔分子筛为催化剂，木质素的裂解率为30%，主产物占裂解产物总量的27%；表明离子热条件所得介-微孔分子筛的孔道结构和酸性质明显优于微孔分子筛和水热条件所得介-微孔分子筛，更适合催化裂解木质素。在此基础上，还进行了离子液体介质中氧化降解木质素、酸性介孔分子筛催化高藜芦酸（木质素裂解主产物）和油酸的酯化、废油脂裂解、乙二醇与苯甲醛的缩合等研究，拓宽了介孔分子筛、离子液体等新型催化材料的应用范围。