Catalyst yield from supported metallocene catalysts
AssigneeFina Technology, Inc.
InventorsEdwar Shoukri Shamshoum, Christopher Garland Bauch
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Abstract
The present invention provides a catalyst and a process for increased catalyst activity and polymer yield. The catalyst system used in the process includes at least two supported metallocene catalyst precursor in combination with an oxyorganoaluminum. The process can be applied to the polymerization of olefins, preferably olefin of three carbon atoms and higher, particularly propylene. The catalyst activity and polymer yield for a dual supported metallocene catalyst are increased over that for a single supported metallocene catalyst. The polymer produced by this dual supported metallocene system has a relatively broad molecular weight distribution.
Claims16
A process for the polymerization of propylene consisting of:
- (a) selecting two syndiospecific metallocene catalyst precursors of the formula:
- R".sub.b (CpR.sub.5-b) (CpR'.sub.5-b)MR*.sub.v-2
- where R" is a bridge imparting stereorigidity to the structure to the metallocene by connecting the two cyclopentadienyl rings, b is 1, Cp is a cyclopentadienyl ring, R and R' are substituents on the cyclopentadienyl rings and are a hydride or a hydrocarbyl from 1-9 carbon atoms, each R and R' being the same or different, each (CpR.sub.5-b) and (CpR'.sub.5-b) are different and bilateral symmetry exists for (CpR.sub.5-b) for the distal substituents, M is a Group IIIB, IVB, VB or VIB metal, R* is a hydride, a halogen or a hydrocarbyl from 1-20 carbon atoms, v is the valence of M, wherein each metallocene catalyst precursor is different;
- (b) supporting the metallocene catalyst precursors on a silica treated with an oxyorganoaluminum compound;
- (c) contacting the supported metallocene catalyst with an aluminum alkyl to activate the catalyst;
- (d) introducing said catalyst into a polymerization reaction zone containing propylene;
- (e) withdrawing a polypropylene product.
Dependencies are inferred from the claim text.