多级孔聚合物微球负载烯烃催化剂催化丙烯聚合研究

The skill of immobilization of polymerization catalyst is the key technique to realize the large-scale industrial production of polypropylene. Comparing with traditional inorganic supports, organic polymer catalyst supports have the advantages of having well-defined structures, controlled functional groups, etc. For now, studies in the field of organic polymer catalyst support are mainly focused on the design and control of pore structures. As a result, comparatively speaking, there are less reports on immobilization and polymerization by using these supports. In fact, most of the polymerization works that adopted polymer catalyst supports have only performed ethylene polymerization. The main purpose of this project is to prepare a kind of polypropylene catalysts by using hierarchical porous polymer supports and to catalyze the polymerization of propylene. To be specific, it is intended to adjust and control the structure of hierarchical porous polymer micro-spheres, which bearing different functional groups, through manipulating the reaction conditions. Moreover, the immobilization methods of Ziegler-Natta catalyst and the metallocene catalyst on such supports with stability and long life will be explored, respectively. Subsequently, the supported catalysts are meant to be used to catalyze the polymerization of propylene, along with that, the relationship between catalytic activities and catalytic efficiency will be revealed by the means of reaction dynamics analysis. Further, the effect of confined space caused by hierarchical porous structure on the microstructure, polymer morphology and macroscopic properties of polypropylene will also be investigated. The main innovative point of this proposal has three aspects: Firstly, a kind of polymer support, for the first time in history, is used for catalytic polymerization of propylene; Secondly, polypropylene with some unique properties can be synthesized applying the confined space effect introduced by hierarchical pores; Finally, based on the phenomenon of confined polymerization that gradually observed, the origin of confined space effect will be revealed and a model will also be built.

催化剂的负载化是实现聚丙烯大规模产业化生产的关键技术环节。相较传统无机载体，有机聚合物载体有诸如结构明确、官能团可控等优点。目前，有机聚合物载体的研究主要集中于孔结构设计与实现方面，而实际用于负载和烯烃催化的报道较少，且主要集中于乙烯催化领域。本项目旨在研究一类多级孔聚合物载体负载多种聚丙烯催化剂催化丙烯聚合，包括：通过调节反应条件，实现对一类含有不同官能团的多级孔聚合物微球载体结构的调控；探索负载方法，实现载体分别与齐格勒-纳塔催化剂和茂金属催化剂的稳定键接；应用负载化催化剂催化丙烯聚合，从反应动力学等角度揭示催化行为与催化效率间关系；探究多级孔空间限制作用对聚丙烯链段结构、凝聚态结构以及宏观性能的影响。本研究主要创新包括：一类聚合物载体首次用于丙烯催化聚合；利用载体空间限制效应制备结构和性能特殊的聚丙烯；根据受限聚合现象，构建多级孔空间限制效应原理模型。

目前，工业上聚丙烯催化剂已经发展至第六代，工业上烯烃聚合反应通常是非均相的，催化剂基本都需要进行负载化为形态较好的固体催化剂，以确保聚合反应和产物形态可控。然而，相对于催化剂的蓬勃发展，催化剂负载化的研究相对滞后，严重制约了新型催化剂的产业化进程。相较无机载体，多孔有机聚合物载体有结构明确、官能团可控等优点。本项目以一类含氮官能团多级孔交联共聚物为载体负载催化剂，研究丙烯催化聚合行为。主要研究内容包括：应用种子聚合法制备苯乙烯、二乙烯基苯、含氮官能团单体三元共聚多孔微球，通过调节反应条件、配比、官能团种类等实现对孔结构和官能团的双重调控；选择不同给电子体，在氰基官能化载体上负载聚丙烯Z-N催化剂，通过调节反应条件实现催化剂的高效负载；研究不同结构载体负载催化剂的催化过程，全面评价了这类聚合物微球用作聚丙烯催化剂载体的性能，实验结合理论模拟，建立了载体孔结构和聚丙烯产物结构的关系。初步实现了载体的放大，能够一批次制备百克以上、粒径均一、BET比表面积大于40 m2/g的氰基官能化多孔微球，用于聚烯烃中试研究。