Efficient Slurry-Phase Homopolymerization of Ethylene to Branched Polyethylenes Using -Diimine Nickel(II) Catalysts Covalently Linke

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• 作者：Henri S. Schrekker ; Vasily Kotov ; Peter Preishuber-Pflugl ; Peter White ; Maurice Brookhart
• 刊名：Macromolecules
• 出版年：2006
• 出版时间：September 19, 2006
• 年：2006
• 卷：39
• 期：19
• 页码：6341 - 6354
• 全文大小：627K
• 年卷期：v.39,no.19(September 19, 2006)
• ISSN：1520-5835

文摘

-Diimine nickel(II) complexes covalently linked to a silica support were obtained by the reactionof an amino- or hydroxy-functionalized -diimine nickel complex with silica particles treated with trimethylaluminum. These silica-supported aryl -diimine nickel(II) precatalysts linked via an amino (1a) or hydroxyfunctionality (1b-c) at the p-aryl position, and precatalysts linked via one (2a) or two (2b) hydroxy functionalitiesin the alkyl backbone were used in slurry polymerizations of ethylene to produce branched polyethylenes. Activationof precatalysts with ethylaluminum sesquichloride was effective even at very low Al/Ni ratios of 48. Initialpolymerizations, performed at 60 C and 150 psig ethylene, showed excellent productivities of up to 10.8 kg PEper gram of 1b (3.0 wt % nickel loading). Low productivities at temperatures above 60 C can in part be overcomeby increase in ethylene pressure. For example, a productivity of 6.0 kg PE per gram of 1b (3.0 wt % nickelloading) was obtained at 80 C and 700 psig ethylene. The best polymerization productivities were obtained withtrimethylaluminum as a traceless silica-linker, however, tetrachlorosilane and trichloroborane are attractivealternatives. Branching densities can be controlled by choice of ortho-aryl substituents. No reactor fouling occurswith these supported catalysts.