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US 7,745,551 B2Granted
Low gel chromium catalysis
AssigneeTotal Petrochemicals Research Feluy
InventorsPhilippe Bodart, Philippe Marechal, Eric Damme
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Abstract
The present invention discloses the use of a chromium-based catalyst system in two serially connected loop reactors for copolymerising ethylene and a comonomer, at reduced productivity, the final polyethylene having a reduced amount of gel.
Claims11
A method for the polymerization of ethylene in a double loop reactor system comprising first and second interconnected loop reactors comprising:
- a) introducing an ethylene monomer, and a diluent carrier liquid into a first loop reactor of said reactor system;
- b) supplying a polymerization catalyst system comprising a supported chromium-based catalyst component to said first loop reactor;
- c) circulating said diluent liquid and ethylene monomer through said first loop reactor while polymerizing said ethylene monomer in the presence of said catalyst system to produce a slurry of polymer fluff particles in said diluent carrier liquid;
- d) withdrawing said slurry from said first loop reactor and supplying said withdrawn slurry to said second loop reactor;
- e) introducing an ethylene monomer and a diluent carrier liquid into said second loop reactor;
- f) circulating said diluent liquid and ethylene monomer through said second loop reactor while polymerizing said ethylene monomer in the presence of said catalyst system to produce a slurry of polymer particles in said diluent in said second reactor;
- g) controlling the polymerization conditions in said first and second reactors to produce a final ethylene polymer at a productivity of less than 3500 grams of polymer per gram of catalyst component and wherein said first and second reactors are operated under conditions such to produce a polymer having a mono modal polydispersity, such conditions comprising operating the first and second reactors at substantially the same temperature;
- h) recovering said ethylene polymer from said second loop reactor.
5 more elements
Dependencies are inferred from the claim text.