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US 6,444,765 B1Granted
Olefin polymerization process for producing broad MWD polymers
AssigneeEquistar Chemicals, LP
InventorCraig C. Meverden
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Abstract
An olefin polymerization process is described. The process comprises preparing a catalyst system by premixing a first organoaluminum with a supported boraaryl catalyst and then polymerizing an olefin in the presence of the premixed supported catalyst, an activator and a second organoaluminum. The process produces polyolefins having broad and/or bimodal molecular weight distributions compared to the process in which either the first or the second organoaluminum is not used.
Claims9
A process for polymerizing olefins to form a polyolefin product which comprises:
- (a) preparing a catalyst system by premixing a first organoaluminum selected from the group consisting of triisobutyaluminum and triethylaluminum with a supported catalyst comprising a support and an organometallic compound comprising zirconium and at least one boraaryl ligand, wherein the catalyst system has an aluminum:zirconium ratio greater than about 100:1 when the first organoaluminum is triisobutyaluminum and the catalyst system has an aluminum:zirconium ratio less than about 20:1 when the first organoaluminum is triethylaluminum;
- and
- (b) polymerizing an olefin in the presence of the catalyst system, an activator and a second organoaluminum, wherein the second organoaluminum is different from the first organoaluminum;
- wherein the polyolefin product is a bimodal molecular weight distribution polyolefin.
1 more element
Dependencies are inferred from the claim text.