用多孔大空阻共价有机骨架过渡金属催化剂合成超高分子量聚烯烃

In recent years, we have developed several types of new non-metallocene olefin polymerization catalysts of Ti(IV), Zr(IV) and Hf(IV) with bulky tetra-dentate ligands, some of which show high catalytic activity, long catalytic lifetime, good thermostability and produce ultra-high molecular weight polymers for ethylene and propylene polymerization reactions upon activation with adequate co-catalysts. We have recently also developed a type of self-supported olefin polymerization catalysts, porous coordination polymers of zirconium, which show high catalytic activity, long catalytic lifetime and produce high molecular weight polyethylene with bimodel molecular weight distribution and containing less ashes. However, this kind of catalysts show relatively poor thermostability. In order to develop self-supported catalysts with better catalytic performance and being able to produce ultrahigh molecular weight polyethylene and polypropylene, in this project, a series of self-supported porous olefin polymerization catalysts in the form of covalent organic frameworks are going to be designed and synthesized with the above-mentioned Ti, Zr and Hf complexes as building blocks. Their catalytic properties for the polymerization of ethylene and propylene in the presence of a suitable cocatalyst are going to be studied in detail. The effects of the structure and composition on the performance of the catalysts will be examined for developing better catalysts and improving the polymerization reaction conditions. We hope that, by carrying out this research project, high-performance new self-supported catalysts for the production of ultrahigh molecular weight polyethylene and polypropylene could be developed.

我们课题组最近开发出几种高性能非茂大空阻四齿配体钛、锆、铪烯烃聚合催化剂，其中一些催化剂经适当助催化剂活化后，对乙烯或丙烯聚合表现出催化活性高、寿命长、热稳定性好、生产的聚合物具有超高分子量等特点。我们还开发出一种自固载型含锆多孔配位聚合物催化剂，这种催化剂活性高、寿命长、无需负载化、生产的聚乙烯呈双峰分布、分子量高、含灰分少。美中不足是此种催化剂热稳定性较差。为开发出性能更佳、可生产超高分子量聚乙烯和聚丙烯的自固载型催化剂，本项目拟在前期工作基础上，以上述大空阻四齿配体钛、锆、铪催化剂为结构基元，设计合成一系列新型自固载多孔大空阻共价有机骨架结构催化剂，系统研究催化剂结构和组成对乙烯、丙烯聚合活性、产物结构、分子量及其分布、形态和堆密度的影响，以期开发出具有自主知识产权、活性高、寿命长、可生产超高分子量聚乙烯和等规聚丙烯的高性能自固载型催化剂体系。

聚烯烃树脂是人类社会使用量最大的合成树脂，已经广泛应用于人类生产生活的各个方面。随着人类社会的不断发展，对聚烯烃材料的需求也不断提高，要求聚烯烃产业界和学术界不断开发新催化剂技术和新聚烯烃材料。另一方面，单点烯烃聚合催化剂需要负载化后才能在工业装置上应用，而现有负载化方法会导致催化剂活性大幅度下降，因此有必要开发新负载化方法和途径。我们课题组近年来一直致力于开发高性能茂金属和非茂金属烯烃聚合催化剂以及探索烯烃聚合催化剂自固载化的方法，在本项目中，我们合成出一系列自固载型多孔共价有机骨架水杨醛亚胺单茂铬催化剂、单核大空阻双酚胺三齿和四齿配体钛、锆催化剂以及单茂三价稀土和铬催化剂，研究了新催化剂对相关烯烃聚合反应的催化性能，获得了两种性能优良的多孔共价骨架自负载催化剂体系和多个单核茂金属和非茂金属催化剂。其中自固载型多孔共价骨架水杨醛亚胺单茂铬催化剂具有催化活性高、寿命长、可生产超高分子量聚乙烯的特点，具有良好的应用前景；所合成的含大空阻取代基胺双酚四齿配体钛和锆催化剂对乙烯/1-己烯共聚反应显示出非常高的催化活性和良好的共单体插入率，而且催化剂寿命长，适合用于生产线性低密度聚乙烯和低共单体含量聚烯烃弹性体材料，有良好的应用前景。