Metallocene derivatives as active supports of zirconium-based catalysts for ethene polymerization

Cyclopentadienyl magnesium chloride (MgClCp) and its functionalized. deriva tives represent original and interesting supporting materials to heterogeni ze metallocene catalysts for olefin polymerizations. The synthesis of MgClC p, its functionalization, and the preparation of a catalytic system in whic h the ZrCl2(Flu)(+) moiety is joined on the support through a cyclopentadie nyl ligand are reported. This catalyst was tested in ethene polymerization, and both the catalytic activity and properties of the produced polymer wer e measured. Its performance was compared with that shown by the catalyst Zr Cl(2)CpFlu employed under the same conditions for both unsupported and conv entional supports, such as MgCl2. The results showed a remarkable improveme nt in terms of the activity and polymer properties with these heterogenized catalysts. Moreover, this system showed stability toward leaching processe s and was characterized by good morphological control of the growing polyme r. Finally, catalysts in which [HB(3,5-Me(2)pyrazolyl)(3)]ZrCl2+ and [HB(3, 5-Me(2)pyrazolyl)(3)]ZrClOtBu(+) moieties were bonded to a functionalized M gClCp- support were also synthesized and tested. The results showed that th e proposed supports could be usefully used to heterogenize tailored metallo cene homogeneous catalysts. In fact, new catalysts were prepared that combi ned the peculiar advantages of both heterogeneous and homogeneous catalysts and overcame the disadvantages of the latter, such as a lack of morphology and reactor fouling. (C) 2001 John Wiley & Sons, Inc.