Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
Molecules. 2010 Dec 16;15(12):9323-39. doi: 10.3390/molecules15129323.
This article reveals the effects of mixed activators on ethylene polymerization and ethylene/1-hexene copolymerization over MgCl₂/SiO₂-supported Ziegler-Natta (ZN) catalysts. First, the conventional ZN catalyst was prepared with SiO₂ addition. Then, the catalyst was tested for ethylene polymerization and ethylene/1-hexene (E/H) co-polymerization using different activators. Triethylaluminum (TEA), tri-n-hexyl aluminum (TnHA) and diethyl aluminum chloride (DEAC), TEA+DEAC, TEA+TnHA, TnHA+ DEAC, TEA+DEAC+TnHA mixtures, were used as activators in this study. It was found that in the case of ethylene polymerization with a sole activator, TnHA exhibited the highest activity among other activators due to increased size of the alkyl group. Further investigation was focused on the use of mixed activators. The activity can be enhanced by a factor of three when the mixed activators were employed and the activity of ethylene polymerization apparently increased in the order of TEA+ DEAC+TnHA > TEA+DEAC > TEA+TnHA. Both the copolymerization activity and crystallinity of the synthesized copolymers were strongly changed when the activators were changed from TEA to TEA+DEAC+TnHA mixtures or pure TnHA and pure DEAC. As for ethylene/1-hexene copolymerization the activity apparently increased in the order of TEA+DEAC+TnHA > TEA+TnHA > TEA+DEAC > TnHA+DEAC > TEA > TnHA > DEAC. Considering the properties of the copolymer obtained with the mixed TEA+DEAC+TnHA, its crystallinity decreased due to the presence of TnHA in the mixed activator. The activators thus exerted a strong influence on copolymer structure. An increased molecular weight distribution (MWD) was observed, without significant change in polymer morphology.
本文揭示了混合活化剂对 MgCl₂/SiO₂负载的齐格勒-纳塔（ZN）催化剂上乙烯聚合和乙烯/1-己烯共聚的影响。首先，通过添加 SiO₂制备了传统的 ZN 催化剂。然后，使用不同的活化剂测试了该催化剂在乙烯聚合和乙烯/1-己烯（E/H）共聚中的性能。三乙基铝（TEA）、三正己基铝（TnHA）和二乙基氯化铝（DEAC）、TEA+DEAC、TEA+TnHA、TnHA+DEAC、TEA+DEAC+TnHA 混合物均用作本研究中的活化剂。结果发现，在单独使用活化剂进行乙烯聚合的情况下，由于烷基基团增大，TnHA 表现出比其他活化剂更高的活性。进一步的研究集中在使用混合活化剂上。当使用混合活化剂时，活性可提高三倍，并且乙烯聚合活性明显按照 TEA+DEAC+TnHA > TEA+DEAC > TEA+TnHA 的顺序增加。当将活化剂从 TEA 改为 TEA+DEAC+TnHA 混合物或纯 TnHA 和纯 DEAC 时，合成共聚物的共聚活性和结晶度均发生强烈变化。对于乙烯/1-己烯共聚，活性明显按照 TEA+DEAC+TnHA > TEA+TnHA > TEA+DEAC > TnHA+DEAC > TEA > TnHA > DEAC 的顺序增加。考虑到使用混合 TEA+DEAC+TnHA 获得的共聚物的性能，由于混合活化剂中存在 TnHA，其结晶度降低。因此，活化剂对共聚物结构有很强的影响。观察到分子量分布（MWD）增加，而聚合物形态没有明显变化。
