Abstract
Treatment of hydroxylated silica or alumina with tris(perfluorophenyl)borane ( 1), bis(perfluorophenyl)borane ( 2) or bis(perfluorophenyl)boron chloride ( 3), provides borane-functionalized supports of variable composition, as revealed by in situ monitoring by 19 F NMR spectroscopy and/or elemental analysis. These chemically treated supports can be impregnated with Cp 2ZrMe 2 to provide supported catalysts for ethylene polymerization. Although some of these supported catalysts are active for ethylene polymerization in the presence of alkylaluminum compounds (e.g., TMA, TIBAL), all of these catalysts are more efficiently activated in the presence of small quantities of methyl aluminoxane, even at very low Al:Zr ratios of 10:1. The polymer properties are quite similar to those produced using the soluble catalyst Cp 2ZrMe 2/B(C 6F 5) 3, again in the presence of MAO at low loading. A variety of experiments suggest that minimal leaching of the metallocene complex from the support occurs under the conditions studied; in particular, production of polyethylene with high bulk densities (>0.2 g/cm 3) and little reactor fouling, even at elevated temperature in toluene slurry, is observed.
Published Version
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