钯纳米胶囊限域空间催化烯烃聚合反应过程研究及产品结构调控

Coordination catalytic polymerization is an effective approach for controlling synthesis of functional polyolefin with the control tacticity, which has multiply significance on reducing energy consumption, saving fossil resource, in-depth processing products’ structures and developing the downstream industry chain of olefin based on coal. For improving the catalytic activity and polyolefins’ tacticity during their catalytic process, we design and construct a new catalytic system of bifunctional ligands chelating palladium nanocapsule reactor with the both characteristics of a “confined geometry space” and the synergy catalytic function of cationic metal activated by the anionic structure units. In the project, we focus on controlling microstructure of functional polyolefin and its’ formation process mechanism within the confined space of nanocapsule reactor with uniform and controllable physical chemical properties, such as morphologies, particle size, pore size and microstructure etc., based on microfluidic technique, and which make the control of polyolefins’ microstructure to be true. Thereof, we investigate the correlative of polyolefin properties including molecular weight and its’ distribution, the content of polar monomers and tacticity of products with catalysts’ properties, and found the regulation law of tuning their physical properties of functional polyolefin products. Subsequently, we establish reaction kinetics model and expound the chemical adsorption behavior of olefin monomer molecules around the catalytic active centers, and characterize their dynamic formation process and the evolution process using the real-time, in-situ technologies. Theoretical calculation is combined with experimental results for further understand the synergistic catalytic activation mechanism between anionic structure units with Lewis acid and cationic palladium units on the molecular level. In a word, the follow-up study has prominent academic significance and application value owing to help for understanding its’ catalytic nature deeply, enrich the catalytic system of olefin polymerization using nanocapsule reactor and enlarge production of high-quality functional polyolefin.

通过配位催化聚合获得功能化聚烯烃产品，具有低能耗、化石资源利用、产品结构深度精细加工以及发展煤制烯烃下游产业链等多重意义。本课题基于配位催化聚合催化活性和立体选择性限制因素基础上，设计并构建了一种具有“限域空间”和阴、阳离子协同活化催化作用机制的双功能配体螯合钯纳米胶囊反应器，发展了基于微流控技术的纳米胶囊催化剂可控制备的研究方法，建立了聚烯烃微结构的可控调节规律及其与催化剂结构的相互关系，阐明了烯烃单体分子在催化活性中心周围的化学吸附行为及其反应动力学特性，实时、实空间地原位表征和分析了催化活性中心的形成及其动态演变过程，理论与实验相结合，在分子水平上深入认识阴、阳离子结构单元协同活化催化作用机制。上述研究对于深入认识配位催化聚合反应本质，丰富高效催化烯烃聚合催化剂体系，推进优质功能化聚烯烃产品的工业化放大生产，具有重要的学术意义和应用价值。

将低碳烯烃通过催化聚合法高效转化成高附加值的且具有精细结构的聚合物产品，具有低能耗、化石资源化综合利用、产品结构深度加工以及发展煤制烯烃下游产业链等多重意义。本项目研究并设计合成了具有阴、阳离子结构单元的酸性质子型离子液体和纳米胶囊钯催化剂，发展了一种多级膜的微膜反应装置平台，用于连续化制备具有限域反应环境的纳米胶囊钯催化剂，调控实现了胶囊钯催化剂的尺寸范围100 nm 左右；拓展了强极性质子型离子液体和含羟基的醇类化合物对烯烃催化聚合反应的强化促进作用，探讨了烯烃聚合物产品结构与催化剂结构的相互关系，当极性质子酸性吡啶基离子液体加入时，烯烃催化聚合的反应活性明显增加，特别是以异丁烯作底物，其催化转化率达到92.7%，二聚产物的选择性为77.3%，醇羟基化合物使得催化聚合产物的选择性更加倾向于单一性，二聚产物的选择性提升了近15%左右，聚合产物的产品质量得到明显提升；烯烃聚合催化体系的循环稳定性，也是提升产品质量的重要影响因素，经静置分离回收的催化剂，可循环使用7次仍能保持活性和选择性不变，深入探讨的催化活性失活机理，确定了碳化层的形成是造成活性丢失的主要原因；利用原位核磁技术，对烯烃催化聚合反应过程实时、实空间地监控，分子水平上分析并探讨了其催化聚合的反应机制，发现了烯烃催化聚合的逐级链增长的“step-by-step”的动态演变过程，深入认识了烯烃催化聚合反应的本质。这些研究结果将为后续高效单一催化选择性的烯烃聚合催化体系的建构及放大化生产制备提供不可或缺的实验数据及技术支撑。