Processes for preparing metallocene-based catalyst systems for the control of long chain branch content
Methods for preparing a metallocene-based catalyst composition that can impact the long chain branching of ethylene homopolymers and copolymers produced using the catalyst composition are described. The catalyst composition can be prepared by contacting a metallocene compound, a hydrocarbon solvent, and a first organoaluminum compound for a first period of time to form a metallocene solution, and then contacting the metallocene solution with an activator-support and a second organoaluminum compound for a second period of time to form the catalyst composition.
1. A catalyst composition comprising:
(i) a metallocene solution comprising:
a metallocene compound comprising rac-ethylene-bis(indenyl) zirconium dichloride,
a hydrocarbon solvent comprising an olefin solvent and/or an alkane solvent, and
a first organoaluminum compound comprising triisobutylaluminum;
(ii) an activator-support; and
(iii) a second organoaluminum compound.
2. The catalyst composition of claim 1 , wherein the second organoaluminum compound comprises triisobutylaluminum and/or tri-n-octylaluminum.
3. The catalyst composition of claim 1 , wherein:
the second organoaluminum compound comprises trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum ethoxide, diethylaluminum chloride, or any combination thereof.
4. The catalyst composition of claim 1 , wherein the activator-support comprises a fluorided solid oxide, a sulfated solid oxide, a phosphated solid oxide, or a combination thereof.
5. The catalyst composition of claim 1 , wherein the catalyst composition is substantially free of aluminoxane compounds, organoboron or organoborate compounds, ionizing ionic compounds, or combinations thereof.
6. The catalyst composition of claim 1 , wherein:
a weight ratio of the metallocene compound to the activator-support is from 1:1 to 1:100,000; and
a molar ratio of the first organoaluminum compound to the second organoaluminum compound is from 1000:1 to 1:1000.
7. The catalyst composition of claim 6 , wherein:
the activator-support comprises fluorided silica-alumina, fluorided silica-coated alumina, sulfated alumina, or any combination thereof; and
the hydrocarbon solvent comprises 1-hexene and/or heptane.
8. A catalyst composition comprising:
(i) a metallocene solution comprising:
a metallocene compound comprising rac-ethylene-bis(indenyl) zirconium dichloride,
a hydrocarbon solvent comprising an aromatic solvent and/or an alkane solvent, and
a first organoaluminum compound comprising trioctylaluminum;
(ii) an activator-support; and
(iii) a second organoaluminum compound.
9. The catalyst composition of claim 8 , wherein the second organoaluminum compound comprises triisobutylaluminum and/or tri-n-octylaluminum.
10. The catalyst composition of claim 8 , wherein the second organoaluminum compound comprises trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum ethoxide, diethylaluminum chloride, or any combination thereof.
11. The catalyst composition of claim 8 , wherein:
the activator-support comprises a fluorided solid oxide, a sulfated solid oxide, a phosphated solid oxide, or a combination thereof; and
the catalyst composition is substantially free of aluminoxane compounds, organoboron or organoborate compounds, ionizing ionic compounds, or combinations thereof.
12. The catalyst composition of claim 8 , wherein:
a weight ratio of the metallocene compound to the activator-support is from 1:1 to 1:100,000; and
a molar ratio of the first organoaluminum compound to the second organoaluminum compound is from 1000:1 to 1:1000.
13. The catalyst composition of claim 6 , wherein:
the activator-support comprises fluorided silica-alumina, fluorided silica-coated alumina, sulfated alumina, or any combination thereof; and
the hydrocarbon solvent comprises toluene and/or heptane.
14. A catalyst composition comprising:
(i) a metallocene solution comprising:
a metallocene compound comprising methyl(buten-3-yl)methylidene(η5-cyclopentadienyl(η5-2,7-di-tert-butylfluoren-9-ylidene) zirconium dichloride,
a hydrocarbon solvent comprising an aromatic solvent, and
a first organoaluminum compound comprising triisobutylaluminum;
(ii) an activator-support; and
(iii) a second organoaluminum compound.
15. The catalyst composition of claim 14 , wherein the second organoaluminum compound comprises triisobutylaluminum and/or tri-n-octylaluminum.
16. The catalyst composition of claim 14 , wherein the second organoaluminum compound comprises trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum ethoxide, diethylaluminum chloride, or any combination thereof.
17. The catalyst composition of claim 14 , wherein the activator-support comprises a fluorided solid oxide, a sulfated solid oxide, a phosphated solid oxide, or a combination thereof.
18. The catalyst composition of claim 14 , wherein the catalyst composition is substantially free of aluminoxane compounds, organoboron or organoborate compounds, ionizing ionic compounds, or combinations thereof.
19. The catalyst composition of claim 14 , wherein:
a weight ratio of the metallocene compound to the activator-support is from 1:1 to 1:100,000; and
a molar ratio of the first organoaluminum compound to the second organoaluminum compound is from 1000:1 to 1:1000.
20. The catalyst composition of claim 19 , wherein:
the activator-support comprises fluorided silica-alumina, fluorided silica-coated alumina, sulfated alumina, or any combination thereof; and
the hydrocarbon solvent comprises toluene.