精密调控的后过渡金属配合物催化剂及其新型聚乙烯材料

The polyolefin technology represents the developing standard of national petrochemical industry. The current situation of Chinese polyolefin industry produce too much massive polyolefins, but advanced polyolefins in highly demanded; therefore it would be necessary to develop advanced catalysts and techniques within our Chinese companies. The crucially technical problem with ethylene polymerization promoted by the late-transition metal complex pre-catalysts is assumed the “poor thermo-stability”, there is no technique and/or process being under commercializing considered at this moment. Regarding to academic considerations, there are quite limited models of complex pre-catalysts and techniques worthily further investigations. Within the current project, some novel models of the late-transition metal complexes would be designed and synthesized on the hypothesis of the “electron-configuration of complex” suitable for olefin polymerization, meanwhile the finely modifications of present complex pre-catalysts (through varying substituents) enhance the catalytic behavior. More models of complex pre-catalysts would be obtained, of which the thermo-stable catalytic systems are achieved. These catalytic systems highly polymerize ethylene into polyethylenes, and the molecular weights and polydispersity of resultant polyethylenes could be nicely controlled. The detail investigations would be preceded to understand the influences of the different types and molecular structures of late-transition metal complexes on their catalytic behavior of ethylene polymerization and microstructures of obtained polyethylenes; their conclusive observations could regulate the correlations between the kinds and molecular structures of late-transition metal complexes, catalytic activities, the microstructures of resultant polyethylenes. The late-transition metal complex pre-catalysts and their polymerization processes would be improved to meet the requirements of the potential commercialization; iron catalytic systems would target the advanced polyethylenes with highly linearity in various types, meanwhile the nickel analogs would produce branched (or elastomeric) polyethylenes in the sole ethylene polymerization.

聚烯烃技术是衡量一个国家石化发展水平的重要标志.我国聚烯烃现在是中低档过剩和高档短缺，迫切需要解决催化剂与技术的落后局面。后过渡金属配合物催化乙烯聚合的技术瓶颈是“催化体系耐热稳定性差”，没有形成产业化技术和工艺；科学困境在于值得深入研究的催化剂模型和工艺极其有限。本项目将基于烯烃聚合对于“配合物电子构型”原理的要求，展开后过渡金属配合物模型设计合成，以及对已有的配合物催化剂模型进行修饰和性能提高;提供更多有价值的配合物催化剂模型，提高现存模型催化体系耐热稳定性，提高催化乙烯聚合活性，有效调控所得聚乙烯的分子量和分子量分布。研究配合物类型与结构调控乙烯聚合活性和所得聚乙烯微结构的影响，获得配合物类型与结构、催化活性、所得聚合微结构间的规律。提升所得配合物催化剂和聚合工艺的实用价值，利用铁催化体系制备良好品质的高度线性聚乙烯，满足不同需求；利用镍催化乙烯均聚制备支化聚烯烃（或弹性体）。

聚烯烃产业存在巨大的经济利润，然而其研究却出现快速萎缩，聚烯烃催化剂与工艺在过去七十年的发展中逼近了“天花板”，其根源在于新模型催化剂发展以及新结构与高性能的聚烯烃材料难有突破。本项目完成过程中，紧紧围绕过渡金属配合物的设计合成与乙烯催化性能研究，利用不同后过渡金属配合物的特点催化制备“高度线性”或者“高度枝化”聚乙烯产物，获得了新型高性能聚烯烃材料。主要在以下几个方面取得进展：（1）实现了新型催化剂设计制备和已有模型催化剂的改良，部分解决了后过渡金属催化剂“催化体系耐热稳定性差”的问题，并且在部分催化体系中实现了所得聚乙烯微观结构和分子量与分子量分布的精确调控。（2）在实验研究的同时，通过计算化学拟合，直观地揭示了催化剂活性中心的金属净电荷与催化活性呈现线性关系；并利用催化中间体和聚合产物微观结构的分析数据，阐述了不同金属（铁与钴或者镍）催化乙烯聚合机理的差异。（3）利用镍配合物催化乙烯聚合实现了高度枝化聚乙烯甚至弹性体材料的制备，发现“大取代基”引入有利于延长催化剂寿命和提高催化体系的热稳定性，而“吸电子取代基”或者“提高溶解性的叔丁基”引入都有利于提高催化活性，证明聚合过程中“氢迁移导致的链行走”和“金属环化物活性中心”是形成支链的重要原因。（4）确立了铁或钴配合物相似的乙烯聚合特征--获得高度线性产物，部分证实在β-消除时形成端双键产物，不论低聚合度和高聚合度产物中都具有良好端烯再现性，有望提供新型乙烯齐聚催化剂体系和制备新型长链（甚至数万分子量）α-烯烃，具有重要的产业化价值。还开展了新型氮杂原子有机环化物合成的方法学，以及延伸的环境友好与生物质转化的催化体系，为催化剂的设计奠定基础。上述几项进展在国际相关领域和应用领域处于引领地位；研究结果已经发表学术论文84篇，其中SCI收录82篇；申请中国发明专利24件，其中授权专利17件。