Claims
- 1. A gas-phase process for polymerization of olefins in a plug flow reactor, in which at least one olefin monomer is contacted with a catalyst system comprising a magnesium halide supported titanium-containing component, an organoaluminum component, and at least one external electron donor component in which catalyst system components are added through injection points positioned axially along the reactor, comprising:
adding a first external donor component to the reactor at an injection point axially near an injection point for the supported transition metal containing component, and adding at least a second external donor component to the reactor axially downstream from the injection point for the first external donor component.
- 2. The process of claim 1 wherein the second external electron donor is more stereoregulating than the first electron donor.
- 3. The process of claim 1 wherein the first and second external electron donor compounds are organic silicon compounds having a formula Si(OR)nR′4−n, where R and R′ are selected independently from C1-C10 alkyl and cylcoalkyl groups and n=1-4.
- 4. The process of claim 3 wherein the first and second external electron donor compounds are selected from the group consisting of tetraethoxysilane, dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, isobutylisopropyldimethoxysilane, di-tert-butyldimethoxysilane, n-propyltriethoxysilane, isopropyltriethoxysilane, and octyltriethoxysilane.
- 5. The process of claim 1 wherein the first external electron donor is tetraethoxysilane.
- 6. The process of claim 1 wherein the second external electron donor is dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, or isobutylisopropyldimethoxysilane.
- 7. The process of claim 1 wherein the olefin monomer is propylene.
- 8. The process of claim 7 wherein propylene is polymerized with a minor amount of ethylene, C4+ alpha-olefins, or mixtures thereof.
- 9. The process of claim 1 wherein the plug flow reactor is a cylindrical horizontal, subfluidized stirred-bed reactor in which the ratio of length to diameter is greater than 2.
- 10. The process of claim 1 wherein the injection point of the second external donor component is at least 25% of the length of the reactor downstream from the injection point of the first external donor component.
- 11. A gas-phase process for polymerization of olefins in a cylindrical horizontal, subfluidized stirred-bed plug flow reactor, in which at least one olefin monomer is contacted with a catalyst system comprising a magnesium halide supported titanium-containing component, an organoaluminum component, and at least one external silicon-containing electron donor component in which the catalyst system components are added through injection points positioned axially along the reactor, comprising:
adding a first external donor component to the reactor at an injection point axially near an injection point for the supported transition metal containing component, and adding at least a second external donor component, which is more stereoregulating than the first electron donor, to the reactor at least 25% of the length of the reactor axially downstream from the injection point for the first external donor component.
- 12. The process of claim 11 in which at least 95 mole % of the olefin monomer is propylene.
- 13. The process of claim 12 in which the first electron donor is tetraethoxysilane.
- 14. The process of claim 13 in which the second electron donor is dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, or isobutylisopropyldimethoxysilane.
- 15. The process of claim 14 wherein the injection point of the second external donor component is between 25% to 75% of the length of the reactor downstream from the injection point of the first external donor component.
- 16. The process of claim 15 wherein the injection point of the second external donor component is between 40% to 60% of the length of the reactor downstream from the injection point of the first external donor component.
- 17. The process of claim 11 wherein a second cylindrical horizontal, subfluidized stirred bed plug flow reactor is operated in series with the first reactor.
- 18. The process of claim 11 wherein the organoaluminum component is a trialkylaluminum.
- 19. The process of claim 18 wherein the organoaluminum component is a triethylaluminum.
- 20. The process of claim 17 in which a mixture of propylene and ethylene is polymerized in the second reactor.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application No. 60/345,255, filed Jan. 3, 2002, which is incorporated by reference herein.
Provisional Applications (1)
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Number |
Date |
Country |
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60345255 |
Jan 2002 |
US |