Processes for preparing metallocene-based catalyst systems
Methods for preparing single and dual metallocene catalyst systems containing an activator-support are disclosed. These methods can include precontacting of the activator-support and an organoaluminum compound, as well as sequential contacting of two different metallocene compounds to form a dual metallocene catalyst system.
1. A process to produce a catalyst composition, the process comprising:
(i) contacting an activator-support and an organoaluminum compound for a first period of time to form a precontacted mixture; and
(ii) contacting the precontacted mixture with a metallocene compound for a second period of time to form the catalyst composition; wherein:
an activity of the catalyst composition is from about 15% to about 1000% greater than that of a catalyst system obtained by first combining the activator-support and the metallocene compound, and then combining the organoaluminum compound, under the same polymerization conditions.
2. The process of claim 1 , wherein:
the activator-support comprises a fluorided solid oxide, a sulfated solid oxide, a phosphated solid oxide, or a combination thereof; and
the metallocene compound comprises a bridged zirconium or hafnium based metallocene compound with a cyclopentadienyl group and a fluorenyl group.
3. The process of claim 1 , wherein:
the first period of time is at least about 5 minutes; and
the activity of the catalyst composition is from about 25% to about 750% greater than that of a catalyst system obtained by first combining the activator-support and the metallocene compound, and then combining the organoaluminum compound, under the same polymerization conditions.
4. The process of claim 1 , wherein:
the 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; and
the activator-support comprises fluorided silica-alumina, fluorided silica-coated alumina, sulfated alumina, or a combination thereof.
5. The process of claim 1 , wherein:
the weight ratio of the metallocene compound to the activator-support is in a range from about 1:10 to about 1:10,000; and
the weight ratio of the activator-support to the organoaluminum compound is in a range from about 1:5 to about 1000:1.
6. An olefin polymerization process, the olefin polymerization process comprising:
(i) contacting an activator-support and an organoaluminum compound for a first period of time to form a precontacted mixture;
(ii) contacting the precontacted mixture with a metallocene compound for a second period of time to form the catalyst composition; and
(iii) contacting the catalyst composition with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer; wherein:
an activity of the catalyst composition is from about 15% to about 1000% greater than that of a catalyst system obtained by first combining the activator-support and the metallocene compound, and then combining the organoaluminum compound, under the same polymerization conditions.
7. The olefin polymerization process of claim 6 , wherein:
the activator-support comprises fluorided silica-alumina, fluorided silica-coated alumina, sulfated alumina, phosphated alumina, or a combination thereof;
the polymerization reactor system comprises a slurry reactor, a gas-phase reactor, a solution reactor, or a combination thereof; and
the olefin monomer comprises ethylene and the olefin comonomer comprises a C 3 -C 10 alpha-olefin.
8. The process of claim 1 , wherein the weight ratio of the metallocene compound to the activator-support is in a range from about 1:20 to about 1:1000.
9. The process of claim 8 , wherein the metallocene compound comprises a bridged zirconium or hafnium based metallocene compound with a cyclopentadienyl group and a fluorenyl group.
10. The process of claim 9 , wherein the 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 process of claim 1 , wherein the activator-support comprises a fluorided solid oxide.
12. The process of claim 1 , wherein the activator-support comprises a sulfated solid oxide.
13. The process of claim 1 , wherein the activator-support comprises fluorided silica-alumina, fluorided silica-coated alumina, sulfated alumina, or a combination thereof.
14. The process of claim 1 , wherein the metallocene compound comprises an unbridged zirconium or hafnium based metallocene compound containing two cyclopentadienyl groups, two indenyl groups, or a cyclopentadienyl and an indenyl group.
15. The process of claim 1 , wherein the first period of time is from about 30 seconds to about 6 hours.
16. The process of claim 1 , wherein:
the activator-support comprises a fluorided solid oxide, a sulfated solid oxide, a phosphated alumina, or a combination thereof; and
the organoaluminum compound comprises trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, or any combination thereof.
17. The process of claim 16 , wherein the activity of the catalyst composition is from about 25% to about 750% greater than that of a catalyst system obtained by first combining the activator-support and the metallocene compound, and then combining the organoaluminum compound, under the same polymerization conditions.
18. The olefin polymerization process of claim 6 , wherein the polymerization reactor system comprises a loop slurry reactor.
19. The olefin polymerization process of claim 6 , wherein:
the activator-support comprises a fluorided solid oxide, a sulfated solid oxide, a phosphated solid oxide, or a combination thereof; and
the olefin polymer is an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, or an ethylene/1-octene copolymer.
20. The olefin polymerization process of claim 6 , wherein:
the metallocene compound comprises a bridged zirconium or hafnium based metallocene compound with a cyclopentadienyl group and a fluorenyl group; and
the 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.
21. The olefin polymerization process of claim 20 , wherein the catalyst composition is contacted with ethylene and an olefin comonomer comprising 1-butene, 1-hexene, 1-octene, or a mixture thereof.
22. The olefin polymerization process of claim 21 , wherein the activity of the catalyst composition is from about 25% to about 750% greater than that of a catalyst system obtained by first combining the activator-support and the metallocene compound, and then combining the organoaluminum compound, under the same polymerization conditions.