含溴α-二亚胺镍(Ⅱ)配合物的合成、表征及催化乙烯聚合反应

Synthesis and Characterization of α-Diimine Nickel(Ⅱ) Catalyst Containing Br Groups for Ethylene Polymerization

合成了一种新型含溴α-二亚胺及其镍配合物,采用1H NMR、13C NMR、FTIR、元素分析和XPS等方法进行表征.用配合物作为催化剂,以甲基铝氧烷(MAO)为助催化剂催化乙烯聚合得到高支化度的聚乙烯,并研究了聚合条件(如Al/Ni摩尔比、聚合温度以及配体结构)对催化活性的影响,结果表明,在反应温度为25℃,Al/Ni摩尔比为800时,该催化剂催化乙烯聚合活性高达55 g PE/(mol Ni.h.Pa),且催化剂具有较好的热稳定性.与不含吸电子基团Br的同类催化剂相比,活性相当,但催化剂的热稳定性和聚合所得聚乙烯支化度有较大程度的提高.

A new Br-substituted α-diimine compound and its corresponding Ni（Ⅱ） complex,{bis[N,N′-（3-bromo-2,4,6-trimethylphenyl）imino]acenaphthene}dibromonickel,were successfully synthesized and characterized by 1H NMR,13C NMR,elemental analysis,FTIR and XPS.The pre-catalyst 2 activated by methylaluminoxane（MAO） was tested in the polymerization of ethylene.The results show that the catalyst exhibits highly activity[55 g PE/（mol Ni·h·Pa）].The catalyst system 2/MAO shows the highest activity with the 800 of Al/Ni molar ratio at 25 ℃.It is found that the catalyst containing electron-withdrawing groups Br shows better thermal stability and almost the same catalytic activity as the one without groups Br.At the same time,branching degree is increased in the presence of electron-withdrawing groups Br.