Supported metallocene catalysts

摘要

Method employing a supported metallocene catalyst composition in the production of an isotactic ethylene propylene co-polymer. The composition comprises a metallocene component supported on a particulate silica support having average particle size of 10-40 microns, a pore volume of 1.3-1.6 ml/g, a surface area of 200-400 m2/g. An alkylalumoxane cocatalyst component is incorporated on the support. The isospecific metallocene is characterized by the formula:
B(CpRaRb)(FlR′2)MQn  (1)
or by the formula:
B′(Cp′R′aR′b)(Fl′)M′Q′n′  (2)
In the formulas Cp and Cp′ are substituted cyclopentadienyl groups, Fl and Fl′ are fluorenyl groups, and B and B′ are structural bridges. R′ are substituents at the 2 and 7 positions, Ra and R′a are substituents distal to the bridge, and Rb and R′b are proximal to the bridge. M and M′ are transition metals, Q′ is a halogen or a C1-C4 alkyl group; and n′ is an integer of from 0-4.

主权项

1. A supported metallocene catalyst comprising:
(i) an isospecific metallocene catalyst component of the formula:
B′(Cp′R′aR′b)(Fl′)M′Q′n  (2) wherein:
Cp′ is a substituted cyclopentadienyl group;Fl′ is a fluorenyl group;B′ is a structural bridge between Cp′ and Fl′ imparting stereorigidity to said catalyst;wherein B′ is an isopropylidene group;wherein the substituent R′a of said metallocene component is a substituted or unsubstituted phenyl group and the substituent R′b is a methyl group or an ethyl group;M′ is a transition metal selected from the group consisting of titanium, zirconium, hafnium and vanadium;Q′ is a halogen or a C1-C4 alkyl group; andn′ is an integer of from 0-4; (ii) methylalumoxane; and (iii) a particulate silica support characterized by a particle size of 20-35 microns, a surface area of 200-400 m2/gram, a pore volume within the range of 1.3-1.6 ml./gram and a pore diameter within the range of 200-240 Å, and wherein said methylalumoxane is incorporated onto said silica support initially in an amount within the range of 0.4 to 0.7 grams of methylalumoxane per gram of silica support followed by the incorporation of said isospecific metallocene catalyst component.