Activating agents for hafnium-based metallocene components
The present invention discloses an active metallocene catalyst system prepared with a hafnium-based metallocene catalyst system and an activating agent comprising an aluminoxane and a sterically hindered Lewis base.
1. A method comprising:
preparing a metallocene catalyst system by combining a hafnium-based metallocene catalyst component and an activating agent;
wherein the hafnium-based metallocene catalyst component is of formula I
R″(CpR 4 )(FluR′ 8 )HfQ 2 (I)
wherein Cp is a cyclopentadienyl ring; Flu is a fluorenyl ring; each R is the same or different and is hydrogen or a hydrocarbyl radical containing from 1 to 20 carbon atoms; each R′ is the same or different and is hydrogen or a hydrocarbyl radical containing from 1 to 20 carbon atoms; R″ is a structural bridge between two Cp rings; Q is a hydrocarbyl radical having from 1 to 20 carbon atoms, a hydrocarboxy radical having from 1 to 20 carbon atoms or a halogen and can be the same or different from each other; and
wherein the activating agent has a low or no co-ordinating capability and comprises an aluminoxane and a Lewis base, and wherein the activating agent comprises a ratio of Lewis base to total aluminum of from 0.5:1 to 0.9:1.
2. The method of claim 1 , further comprising, prior to the combining of the hafnium-based metallocene catalyst component and the activating agent, forming the activating agent by:
mixing the aluminoxane with the Lewis base; and
reacting the aluminoxane and the Lewis base for a period of time sufficient to reach equilibrium, wherein aluminum alkyl present in the activating agent is neutralized by the Lewis base.
3. The method of claim 2 , wherein the period of time sufficient to reach equilibrium ranges from 30 minutes to 2 hours.
4. The method of claim 1 , wherein the Lewis base is a compound of formula R* a-c E (G-R* b-1 ) c or of formula R* (G-R* b-1 ) c wherein G is a group 15 or 16 element of the Periodic Table, b is equal to the valency of G, E is a group 14 or 15 element of the Periodic Table, a is the coordination number of E, c is an integer from 1 to 4, at most equal to a and each R* is independently a hydrogen or an unsubstituted or substituted hydrocarbyl.
5. The method of claim 1 , wherein the Lewis base is a phenol.
6. The method of claim 1 , wherein the Lewis base is a multi-substituted phenol.
7. The method of claim 1 , wherein the metallocene catalyst system has a ratio Al/Hf of from 100 to 5000.
8. The method of claim 1 , wherein the hafnium-based metallocene catalyst component and the activating agent are combined with a support material.
9. The method of claim 1 , wherein all R in formula I are hydrogen.
10. The method of claim 1 , wherein all R and R′ in formula I are hydrogen.
11. The method of claim 1 , wherein position 3 of the cyclopentadienyl ring is occupied by a non-hydrogen substituent and all other R and R′ are hydrogen.
12. The method of claim 11 , wherein the substituent at position 3 of the cyclopentadienyl ring is methyl or tert-butyl.
13. The method of claim 1 , wherein the R at position 3 of the cyclopentadienyl ring is a hydrogen.
14. The method of claim 1 , wherein the cyclopentadienyl ring is substituted at the position 2, position 4, or both, and wherein all other R are hydrogen.
15. The method of claim 1 , wherein one or more of the R comprises two carbon atoms joined together to form a C 4 -C 6 ring.
16. The method of claim 1 , wherein R″ is an alkylidene group having from 1 to 20 carbon atoms, a germanium group, a silicon group, a siloxane group, an alkyl phosphine group, or an amine group.
17. The method of claim 1 , wherein R″ comprises a hydrocarbyl radical having at least one carbon.
18. The method of claim 1 , wherein R″ comprises CH 2 -CH 2 , Ph 2 C, or Me 2 Si.