Metallocene dimer selective catalysts and processes to produce poly alpha-olefin dimers

1. A process to produce a poly alpha-olefin (PAO), the process comprising:

introducing a C 6 -C 32 alpha-olefin and a catalyst system comprising activator and a metallocene compound into a continuous stirred tank reactor or a continuous tubular reactor under reaction conditions, wherein the alpha-olefin is introduced to the reactor at a flow rate of at least 100 g/hr; and

obtaining a product comprising PAO dimer and optional higher oligomers of alpha-olefin, or a combination thereof, the PAO dimer comprising 96 mol % or more of vinylidene, based on total moles of vinylidene, disubstituted vinylene, and trisubstituted vinylene in the product, and the metallocene compound is represented by the formula:

wherein:

each of R 1 , R 2 , and R 3 is independently hydrogen, a substituted or unsubstituted linear, branched, or cyclic C 1 -C 20 hydrocarbyl group, wherein at least one of R 1 , R 2 , and R 3 is not hydrogen and at least one of R 1 , R 2 , and R 3 is hydrogen;

each of R 4 , R 5 , R 6 , and R 7 is independently hydrogen, a substituted or unsubstituted linear, branched, or cyclic C 1 -C 30 hydrocarbyl group, or one or more of R 4 and R 5 , R 5 and R 6 , or R 6 and R 7 , taken together with the carbon atoms in the indenyl ring to which they are directly connected, collectively form one or more substituted or unsubstituted rings fused to the indenyl ring;

each of R 8 , R 9 , R 10 , R 11 , and R 12 is independently a substituted or unsubstituted linear, branched, or cyclic C 1 -C 30 hydrocarbyl, silylcarbyl, or germanyl group;

M is a group 3, 4 or 5 transition metal;

each X is independently a halogen, a hydride, an amide, an alkoxide, a sulfide, a phosphide, a diene, an amine, a phosphine, an ether, or a C 1 -C 20 substituted or unsubstituted linear, branched, or cyclic hydrocarbyl group, or optionally two or more X moieties may together form a fused ring or ring system; and

m is an integer equal to 1, 2, or 3.

2. The process of claim 1 , wherein the metallocene compound is represented by the formula:

wherein:

each of R 1 , R 2 , and R 3 is independently hydrogen or a substituted or unsubstituted linear, branched, or cyclic C 1 -C 20 hydrocarbyl or silylcarbyl group;

each of R 4 and R 7 is independently hydrogen, a substituted or unsubstituted linear, branched, or cyclic C 1 -C 30 hydrocarbyl or silylcarbyl group;

each of R 8 , R 9 , R 10 , R 11 , and R 12 is independently a hydrogen, or a substituted or unsubstituted linear, branched, or cyclic C 1 -C 20 hydrocarbyl, silylcarbyl, or germanyl group, or optionally at least three of R 8 , R 9 , R 10 , R 11 , and R 12 are not hydrogen;

each of R 13 , R 14 , R 15 , R 16 , R 17 , and R 18 is independently hydrogen or a substituted or unsubstituted linear, branched, or cyclic C 1 -C 20 hydrocarbyl or silylcarbyl group;

M is a group 3, 4 or 5 transition metal;

each X is independently a halogen, a hydride, an amide, an alkoxide, a sulfide, a phosphide, a diene, an amine, a phosphine, an ether, or a C 1 -C 20 substituted or unsubstituted linear, branched, or cyclic hydrocarbyl group, or optionally two or more X moieties may together form a fused ring or ring system; and

m is an integer equal to 1, 2, or 3.

3. The process of claim 1 , wherein the reaction conditions comprise a reactor temperature of about 120° C. or greater and a reactor pressure of from 15 psia to 750 psia.

4. The process of claim 1 , wherein the reaction conditions comprise a catalyst loading of at least 10,000 g alpha-olefin (gAO) per gram of catalyst (gCat).

5. The process of claim 1 , wherein the reaction conditions comprise a flow rate of the catalyst system of at least 6 gCat/hr.

6. The process of claim 1 , wherein the reaction conditions comprise a reactor residence time of less than 5 hours.

7. The process of claim 1 , wherein the product further comprises, based on total moles (100 mol %) of vinylidene, disubstituted vinylene, and trisubstituted vinylene in the product:

up to 4 mol % trisubstituted vinylene,

up to 4 mol % disubstituted vinylene, or

up to 4 mol % trisubstituted vinylene and disubstituted vinylene.

8. The process of claim 7 , wherein the product comprises, based on total moles (100 mol %) of vinylidene, disubstituted vinylene, and trisubstituted vinylene in the product:

98 mol % or more vinylidene, and

up to 2 mol % trisubstituted vinylene,

up to 2 mol % disubstituted vinylene, or

up to 2 mol % trisubstituted vinylene and disubstituted vinylene.

9. The process of claim 8 , wherein the product comprises, based on total moles (100 mol %) of vinylidene, disubstituted vinylene, and trisubstituted vinylene in the product:

98 mol % or more vinylidene, and

up to 1 mol % trisubstituted vinylene,

up to 1 mol % disubstituted vinylene, or

up to 1 mol % trisubstituted vinylene and disubstituted vinylene.

10. The process of claim 9 , wherein the product comprises, based on total moles (100 mol %) of vinylidene, disubstituted vinylene, and trisubstituted vinylene in the product:

98 mol % or more vinylidene, and

up to 0.5 mol % trisubstituted vinylene,

up to 0.5 mol % disubstituted vinylene, or

up to 0.5 mol % trisubstituted vinylene and disubstituted vinylene.

11. The process of claim 1 , wherein each of R 1 , R 2 , and R 3 is independently hydrogen or a substituted or unsubstituted linear, branched, or cyclic C 1 -C 6 hydrocarbyl group.

12. The process of claim 11 , wherein one of R 1 , R 2 , and R 3 is a substituted or unsubstituted linear, branched, or cyclic C 1 -C 6 hydrocarbyl group, and two of R 1 , R 2 , and R 3 are hydrogen.

13. The process of claim 1 , wherein M is Hf.

14. The process of claim 1 , wherein the metallocene compound is represented by the formula:

or a combination thereof.

15. The process of claim 1 , wherein the activator comprises one or more of:

N,N-dimethylanilinium tetrakis(perfluorophenyl)borate,

N,N-dimethylanilinium tetrakis(perfluoro-naphthyl)borate,

triphenylcarbonium tetrakis(perfluorophenyl)borate,

triphenylcarbonium tetrakis(perfluoronaphthyl)borate,

N,N-dimethylanilinium tetrakis(perfluorophenyl)aluminate,

N,N-dimethylanilinium tetrakis(perfluoronaphthyl)aluminate,

alumoxane,

a modified alumoxane, and

an aluminum alkyl.

16. The process of claim 1 , wherein the C 6 -C 32 alpha-olefin is selected from the group consisting of 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, and combinations thereof.

17. The process of claim 1 , wherein the C 6 -C 32 alpha-olefin is selected from the group consisting of 1-hexene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and combinations thereof.

18. The process of claim 1 , wherein the reaction conditions comprise a reactor temperature of from 130° C. to 180° C., a reactor pressure of from 15 psia to 750 psia, and a catalyst loading of from 25,000 g alpha-olefin (gAO) per 1 g catalyst (gCat) to 90,000 gAO/gCat.

19. The process of claim 18 , wherein the reactor conditions comprise a reactor temperature of from 130° C. to 148° C., a reactor pressure of from 30 psia to 100 psia, and a catalyst loading of from 25,000 g alpha-olefin (gAO) per 1 g catalyst (gCat) to 80,000 gAO/gCat.

20. The process of claim 1 , further comprising functionalizing the PAO dimer with a reactant to form a functionalized PAO product followed by hydrogenation.

21. The process of claim 20 , wherein the reactant is a naphthalene and the functionalized PAO product is a naphthalene PAO dimer adduct.

22. The process of claim 20 , wherein the reactant is an anisole and the functionalized PAO product is an anisole PAO dimer adduct.

23. The process of claim 1 , further comprising hydrogenating the product.

24. A process to produce a lubricant comprising a poly alpha-olefin (PAO), the process comprising:

1) introducing a C 6 -C 32 alpha-olefin and a catalyst system comprising activator and a metallocene compound into a reactor under reaction conditions and obtaining a product comprising PAO dimer and optional higher oligomers of alpha-olefin, or a combination thereof, the PAO dimer comprising 96 mol % or more of vinylidene, based on total moles of vinylidene, disubstituted vinylene, and trisubstituted vinylene in the product, and the metallocene compound is represented by the formula:

wherein:

each of R 1 , R 2 , and R 3 is independently hydrogen, a substituted or unsubstituted linear, branched, or cyclic C 1 -C 20 hydrocarbyl group, wherein at least one of R 1 , R 2 , and R 3 is not hydrogen and at least one of R 1 , R 2 , and R 3 is hydrogen;

each of R 4 , R 5 , R 6 , and R 7 is independently hydrogen, a substituted or unsubstituted linear, branched, or cyclic C 1 -C 30 hydrocarbyl group, or one or more of R 4 and R 5 , R 5 and R 6 , or R 6 and R 7 , taken together with the carbon atoms in the indenyl ring to which they are directly connected, collectively form one or more substituted or unsubstituted rings fused to the indenyl ring;

each of R 8 , R 9 , R 10 , R 11 , and R 12 is independently a substituted or unsubstituted linear, branched, or cyclic C 1 -C 30 hydrocarbyl, silylcarbyl, or germanyl group;

M is a group 3, 4 or 5 transition metal;

each X is independently a halogen, a hydride, an amide, an alkoxide, a sulfide, a phosphide, a diene, an amine, a phosphine, an ether, or a C 1 -C 20 substituted or unsubstituted linear, branched, or cyclic hydrocarbyl group, or optionally two or more X moieties may together form a fused ring or ring system; and

m is an integer equal to 1, 2, or 3; and

2) hydrogenating at least a portion of the product from the first oligomerization to form a lubricant.