铁、钴催化剂乙烯聚合原位紫外-可见光谱研究

in situ UV-Vis STUDIES ON IRON AND COBALT CATALYSTS FOR ETHYLENE POLYMERIZATION

利用乙烯常压聚合原位紫外 可见 (UV Vis)光谱技术 ,对 3个铁、钴络合物作为催化剂前体的催化剂体系进行了研究 .3个铁、钴络合物分别为 2 ,6 双 [1 (2 ,6 二甲基苯基亚胺 )乙基 ]吡啶二氯化铁 (a)、2 ,6 双 [1 (2 ,4,6 三甲基苯基亚胺 )乙基 ]吡啶二氯化铁 (b)和 2 ,6 双 [1 (2 ,6 二异丙基苯基亚胺 )乙基 ]吡啶二氯化钴(c) .实验结果表明 ,MAO对络合物催化剂前体的活化作用是一个快速过程 ;在聚合条件下分别观察到 5 6 0、6 30和 5 80nm的活性峰 ,考察了它们在聚合过程中的生长和在加入无水乙醇逐步使催化剂中毒时活性峰的消失规律 .

By using in situ UV-Vis spectroscopic technique for ethylene polymerization under atmospheric pressure, three catalytic systems with different iron or cobalt complexes as catalyst precursor were studied. The corresponding complexes are 2,6-bis[1-(2,6-dimethylphenylimino) ethyl] pyridine iron ( It) dichloride (a), 2,6-bis[1-(2,4,6-trimethylphenylimino) ethyl]pyridine iron (II) dichloride (b) and 2,6-bis[1-(2,6-diisopropylphenylimino) ethyl] pyridine cobalt dichloride (c). The results showed that the activation of MAO to procatalyst is fast; active absorptions at 560 run, 630 mn and 580 nm were observed, respectively. The rule of growth for active absorptions in polymerization and their disappearance when the catalyst was poisoned by anhydrous batches ethanol, were investigated. Catalytic active species and mechanism were discussed.