PROCESS FOR PREPARING POLYALPHA-OLEFINS

Abstract

The invention relates to a process for preparing polyalpha-olefins using a catalyst composition comprising a reaction product of an organometallic complex and a co-catalyst, wherein the comprising an organometallic complex is represented by the general formula: LMXn wherein: (i) L is an organic ligand; (ii) M is a transition metal having a valency of p, wherein the metal M is selected from Ti, Zr, and Hf; (iii) X is an anionic ligand to the metal M, and wherein X is selected from the group consisting of halogens, alkyls, aralkyls, alkoxides, amides, and combinations thereof; (iv) n is the number of X groups and equals p-2.

Claims

1. A process for preparing polyalpha-olefins, comprising: a. providing a feedstream comprising one or more alpha-olefin monomer, wherein the alpha-olefin monomer comprises four to thirty (4-30) carbon atoms; b. contacting the feedstream with a catalyst composition comprising a reaction product of an organometallic complex and a co-catalyst, wherein the organometallic complex is represented by the general formula:
LMX.sub.n wherein: I. L is an organic ligand; II. M is a transition metal having a valency of p, wherein the metal M is selected from Ti, Zr, and Hf; III. X is an anionic ligand to the metal M, and wherein X is selected from the group consisting of halogens, alkyls, aralkyls, alkoxides, amides, and combinations thereof; IV. n is the number of X groups and equals p-2; wherein the organic ligand L is selected from the group consisting of: i. a bridging group bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group; wherein the bridging group contains at least one sp.sup.2 hybridized carbon atom bonded to at least one of the hydrocarbyl groups; ii. a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group; iii. a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group; iv. a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to a tetra-alkyl substituted cyclopentadienyl group and to a 1-indenyl group, wherein the 1-indenyl group comprises a substituent at the second position wherein the substituent is selected from C.sub.3-C.sub.20 alkyl or C.sub.6-C.sub.20 aryl group; v. a substituted or an unsubstituted 1, 2-phenylene bridging group bonded to a substituted or an unsubstituted 1-indenyl group and to a substituted or an unsubstituted 2-indenyl group; vi. a substituted or an unsubstituted 2,2-biphenylene-bridging group bonded to two hydrocarbyl groups, each hydrocarbyl group comprising a substituted indenyl group, wherein the bridging group is bonded at the second position of each of the substituted indenyl group; vii. abridging group comprising a substituted or an unsubstituted styryl moiety bonded to a substituent selected from a Group 16 element of the IUPAC Periodic Table and to a substituted cyclopentadienyl group, wherein the bridging group is bonded to a substituted cyclopentadienyl group at the alpha position of the styryl moiety; viii. a substituted or an unsubstituted 2,2-biphenylene bridging group bonded to a substituted or an unsubstituted indenyl group and to a substituent selected from a Group 15 or a Group 16 element of the IUPAC Periodic Table; ix. a substituted or an unsubstituted 2,2-biphenylene group bonded to a substituent (A) and to a substituent (B), wherein substituent (A) is selected from a Group 15 element of the IUPAC Periodic Table and substituent (B) is selected from a Group 15 or a Group 16 element of the IUPAC Periodic Table, further wherein the group 15 element of substituent (A) is covalently bonded to two sp.sup.2 hybridized carbon atoms; x. a bridging group comprising at least one sp.sup.2 hybridized carbon atom bonded to two substituted or unsubstituted 2-indenyl groups; xi. a substituted or an unsubstituted 1,8-naphthalene-bridging group bonded to two substituted or unsubstituted 2-indenyl groups; and xii. any combination thereof. c. oligomerizing the one or more alpha-olefin monomer in presence of the catalyst composition under conditions sufficient to produce polyalpha-olefins.

2. The process of claim 1, wherein the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group, such as wherein the organometallic complex is selected from the group consisting of: ##STR00055## and any combinations thereof.

3. The process of claim 1, wherein the organic ligand L comprises a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group, such as wherein the organometallic complex is selected from the group consisting of: ##STR00056## and any combinations thereof.

4. The process of claim 1, wherein the organic ligand L comprises a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to a tetra-alkyl substituted cyclopentadienyl group and to a 1-indenyl group, wherein the 1-indenyl group comprises a substituent at the second position wherein the substituent is selected from C.sub.3-C.sub.20 alkyl or C.sub.6-C.sub.20 aryl group, such as wherein the organometallic complex is selected from the group consisting of: ##STR00057## and combinations thereof.

5. The process of claim 1, wherein the organic ligand L comprises a substituted or an unsubstituted 1, 2-phenylene bridging group bonded to a substituted or an unsubstituted 1-indenyl group and to a substituted or an unsubstituted 2-indenyl group; such as wherein the organometallic complex is: ##STR00058##

6. The process of claim 1, wherein the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group bonded to two hydrocarbyl groups, each hydrocarbyl group comprising a substituted indenyl group, wherein the bridging group is bonded at the second position of each of the substituted indenyl group, such as wherein the organometallic complex is: ##STR00059##

7. The process of claim 1, wherein the organic ligand L comprises a bridging group comprising a substituted or an unsubstituted styryl moiety bonded to a substituent selected from a Group 16 element of the IUPAC Periodic Table and to a substituted cyclopentadienyl group, wherein the bridging group is bonded to a substituted cyclopentadienyl group at the alpha position of the styryl moiety; such as wherein the organometallic complex is selected from the group consisting of: ##STR00060## and any combinations thereof.

8. The process of claim 1, wherein the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene bridging group bonded to a substituted or an unsubstituted indenyl group and to a substituent selected from a Group 15 or a Group 16 element of the IUPAC Periodic Table, such as wherein the organometallic complex is: ##STR00061##

9. The process of claim 1, wherein the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene group bonded to a substituent (A) and to a substituent (B), wherein substituent (A) is selected from a Group 15 element of the IUPAC Periodic Table and substituent (B) is selected from a Group 15 or a Group 16 element of the IUPAC Periodic Table, further wherein the group 15 element of substituent (A) is covalently bonded to two sp.sup.2 hybridized carbon atoms, such as wherein the organometallic complex is: ##STR00062##

10. The process of claim 1, wherein the organic ligand L comprises a bridging group comprising at least one sp.sup.2 hybridized carbon atom bonded to two substituted or unsubstituted 2-indenyl groups, such as wherein the organometallic complex is selected from the group consisting of: ##STR00063## and combinations thereof; wherein M is a transition metal having a valency of 4, wherein the metal M is selected from Ti, Zr, and Hf.

11. The process of claim 1, wherein the organic ligand L comprises a substituted or an unsubstituted 1,8-naphthalene-bridging group bonded to two substituted or unsubstituted 2-indenyl groups, such as wherein the organometallic complex is: ##STR00064##

12. The process of claim 1, wherein the one or more alpha-olefin monomer present in the feedstream is selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 4-methyl-1-pentene, 5-methyl-1-nonene, 3-methyl-1-pentene, 3,5,5-trimethyl-1-hexene, vinylcyclohexene, and any combinations thereof.

13. The process of claim 1, wherein the one or more alpha-olefin monomer is oligomerized at a reactor temperature ranging between 25 C. to 150 C.

14. The process of claim 1, wherein the one or more alpha-olefin monomer is oligomerized at a reactor pressure ranging between atmospheric pressure to about 50 psia.

15. The process of claim 1, wherein the cocatalyst is selected from an aluminium containing cocatalyst, a boron-containing cocatalyst, zinc containing cocatalyst, or a combination thereof.

Description

DETAILED DESCRIPTION

[0082] The invention is based, in part, on the discovery of a process for preparing polyalpha-olefins using a catalyst composition comprising an organometallic complex. Advantageously, the polyalpha-olefins prepared from the process of the present invention, demonstrates a balance of high oxidative stability, relatively uniform chemical structure, and a suitable viscosity index at appreciable productivity.

[0083] The following paragraph includes definitions of various terms, expressions and phrases used throughout this specification.

[0084] The use of the words a or an when used in conjunction with the term comprising, including, containing, or having in the claims or the specification may mean one, but it is also consistent with the meaning of one or more, at least one, and one or more than one. The words comprising (and any form of comprising, such as comprise and comprises), having (and any form of having, such as have and has), including (and any form of including, such as includes and include) or containing (and any form of containing, such as contains and contain) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. The method of the invention can comprise, consist essentially of, or consist of particular ingredients, components, compositions, etc., disclosed throughout the specification.

[0085] The term polyalpha-olefin as used herein refers to hydrocarbons or oligomers manufactured by the oligomerization of alpha-olefin monomers. Polyalpha-olefins include for example C.sub.20-24 dimers, C.sub.30-36 trimers, C.sub.40-48 tetramers, C.sub.50-60 pentamers, and C.sub.60+ heavies. Generally, suitable alpha-olefins are represented by the following formula: CH.sub.2CHR where R can be any hydrocarbyl group, such as alkyl, aryl, or aralkyl. For the avoidance of doubt, polyalpha-olefins are distinct from polyolefins (e.g. polyethylene, polypropylene) where polyalpha-olefins are oligomers having relatively a much lower molecular weight, with a much lower number of repeating monomeric units compared to polyolefins having high molecular weight and large number of repeating monomeric units. In various embodiments of the invention, the polyalpha-olefins obtained from the process of the present invention has an average molecular weight (Mw) expressed in terms of g/mol of 200 to 32000, alternatively 300 to 25,000, alternatively 400 to 18,000. The molecular weight provided for the polyalpha-olefins is lower than that of the polyolefins such as polyethylene, which typically have molecular weight in the hundreds of thousands.

[0086] As a general matter, any carbon atom of the various organometallic complexes of the present disclosure may be substituted or unsubstituted, meaning the carbon atom can be attached to one or more hydrogen atoms or one or more of the hydrogen atoms may be replaced with a different moiety, with example substituents including a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, or a heteroatom atom.

[0087] The expression substituted or an unsubstituted cyclopentadienyl group means that a cyclopentadienyl ring may be substituted by one or more substituents selected from hydrogen, a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, a heteroatom atom, or alternatively that a cyclopentadienyl ring is fused to one or more ring system to form a cyclopentadienyl fused ring system. Non-limiting examples of cyclopentadienyl fused ring system includes an indenyl ring, a fused indenyl ring, a substituted indenyl ring, a tetra-hydro indene, a fluorenyl ring, a substituted fluorenyl ring. The fused indenyl ring comprises for example at least one, alternatively two, alternatively three ring systems fused to an indenyl ring. Alternatively, a cyclopentadienyl fused ring system may include one or more ring systems fused with a cyclopentadienyl ring that may be completely saturated or partially saturated in order to attenuate catalyst performance.

[0088] The expression substituted or an unsubstituted indenyl group means that an indenyl ring may be substituted by one or more substituents selected from hydrogen, a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, a heteroatom atom, or alternatively the indenyl ring is fused to one or more ring system to form an indenyl fused ring system.

[0089] The expression substituted or an unsubstituted 2,2-biphenylene group means that a 2,2-biphenylene group may be substituted by one or more substituents selected from hydrogen, a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, or a heteroatom atom.

[0090] The expression substituted or an unsubstituted 1, 2-phenylene bridging group means that a 1, 2-phenylene bridging group may be substituted by one or more substituents selected from hydrogen, a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, or a heteroatom atom.

[0091] The expression substituted or an unsubstituted styryl moiety means that a styryl moiety may be substituted by one or more substituents selected from hydrogen, a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, or a heteroatom atom.

[0092] The expression substituted or an unsubstituted 1,8-naphthalene-bridging group means that a 1,8-naphthalene-bridging group may be substituted by one or more substituents selected from hydrogen, a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, or a heteroatom atom.

[0093] The expression substituted indenyl group or substituted 1-indenyl group or substituted 2-indenyl group means that an indenyl ring may be substituted by one or more substituents selected from hydrogen, a C.sub.1-C.sub.30 alkyl group, a C.sub.6-C.sub.30 aryl group, a heteroatom, or alternatively the indenyl ring is fused to one or more ring system to form a fused indenyl ring system.

[0094] The expression sp.sup.2 hybridized carbon atoms as used herein includes a carbon atom of an aromatic ring, for example, a carbon atom of a phenyl ring and also includes a carbon atom of an alkenyl group, wherein such carbon atom has sp.sup.2 hybridization.

[0095] The expression tetra-alkyl substituted cyclopentadienyl group means a cyclopentadienyl group having a cyclopentadienyl ring substituted by four C.sub.1-C.sub.30 alkyl groups.

[0096] The term hydrocarbyl refers to an organic radical primarily composed of carbon and hydrogen, which may be aliphatic, alicyclic, aromatic, a hydrocarbon ring system, or a fused cyclic ring system, for example a cyclopentadienyl ring or an indenyl ring, or combinations thereof, e.g., aralkyl or alkaryl.

[0097] The expression Group 15 element of the IUPAC Periodic Table means any of the following elements: N, P, As, Sb, Bi.

[0098] The expression Group 16 element of the IUPAC Periodic Table means any of the following elements: O, S, Se, Te, Po.

[0099] Accordingly, the invention is directed to a process for producing polyalpha-olefins, comprising the steps of:

a. providing a feed stream comprising one or more alpha-olefin monomer, wherein the alpha-olefin monomer comprises four to thirty (4-30) carbon atoms;
b. contacting the feed stream with a catalyst composition comprising a reaction product of an organometallic complex and a co-catalyst, wherein the organometallic complex is represented by the general formula: LMX.sub.n wherein: [0100] I. L is an organic ligand; [0101] II. M is a transition metal having a valency of p, wherein the metal M is selected from Ti, Zr, and Hf; [0102] III. X is an anionic ligand to the metal M, and wherein X is selected from the group consisting of halogens, alkyls, aralkyls, alkoxides, amides, and combinations thereof; [0103] IV. n is the number of X groups and equals p-2;
wherein the organic ligand L is selected from the group consisting of: [0104] i. a bridging group bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group; wherein the bridging group contains at least one sp.sup.2 hybridized carbon atom bonded to at least one of the hydrocarbyl groups; [0105] ii. a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group; [0106] iii. a disubstituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group; [0107] iv. a disubstituted alkyl-silyl bridging group, wherein the bridging group is bonded to a tetra-alkyl substituted cyclopentadienyl group and to a 1-indenyl group, wherein the 1-indenyl group comprises a substituent at the second position, wherein the substituent is selected from C.sub.3-C.sub.20 alkyl or C.sub.6-C.sub.20 aryl group; [0108] v. a substituted or an unsubstituted 1, 2-phenylene bridging group bonded to a substituted or an unsubstituted 1-indenyl group and to a substituted or an unsubstituted 2-indenyl group; [0109] vi. a substituted or an unsubstituted 2,2-biphenylene-bridging group bonded to two hydrocarbyl groups, each hydrocarbyl group comprising a substituted indenyl group, wherein the bridging group is bonded at the second position of each of the substituted indenyl group; [0110] vii. a bridging group comprising a substituted or an unsubstituted styryl moiety bonded to a substituent selected from a Group 16 element of the IUPAC Periodic Table and to a substituted cyclopentadienyl group, wherein the bridging group is bonded to a substituted cyclopentadienyl group at the alpha position of the styryl moiety; [0111] viii. a substituted or an unsubstituted 2,2-biphenylene bridging group bonded to a substituted or an unsubstituted indenyl group and to a substituent selected from a Group 15 or a Group 16 element of the IUPAC Periodic Table; [0112] ix. a substituted or an unsubstituted 2,2-biphenylene group bonded to a substituent (A) and to a substituent (B), wherein substituent (A) is selected from a Group 15 element of the IUPAC Periodic Table and substituent (B) is selected from a Group 15 or a Group 16 element of the IUPAC Periodic Table, further wherein the group 15 element of substituent (A) is covalently bonded to two sp.sup.2 hybridized carbon atoms; [0113] x. a bridging group comprising at least one sp.sup.2 hybridized carbon atom bonded to two substituted or unsubstituted 2-indenyl group; [0114] xi. a substituted or an unsubstituted 1,8-naphthalene-bridging group bonded to two substituted or an unsubstituted 2-indenyl group; and [0115] xii. any combination thereof.
c. oligomerizing the one or more alpha-olefin monomer in presence of the catalyst composition under conditions sufficient to produce polyalpha-olefins.

[0116] In various embodiments of the invention, the poly-alpha olefins once formed may be hydrogenated in presence of a hydrogenation catalyst to form a partially saturated or a completely saturated polyalpha-olefin oligomers. In various embodiments of the invention, the polyalpha-olefin is hydrogenated by reaction with hydrogen gas in the presence of a catalytic amount (0.1 to 5 wt. %) of a hydrogenation catalyst. Examples of suitable hydrogenation catalysts are metals of Group VIII of the Periodic Table such as iron, cobalt, nickel, rhodium, palladium and platinum. These catalysts may be deposited on alumina, on silica gel, or on activated carbon in preferred embodiments of the invention. Of these catalysts, palladium and nickel are preferred. Palladium on activated carbon and nickel on kieselguhr are especially preferred. In an embodiment of the invention, the synthesized polyalpha-olefins has some degree of unsaturation. The unsaturation is primarily in the form of vinylidene groups. In an aspect of the invention, the oligomer is synthesized as an unsaturated oligomer, and it is subsequently hydrogenated to produce a saturated oligomer.

[0117] In various embodiments of the invention, the polyalpha-olefins may have some level of unsaturation, such as the presence of double bonds. The unsaturated bonds may be hydrogenated in a hydrogenation reaction. The hydrogenation reaction can be carried out in the presence or absence of solvents. Solvents are necessary only to increase the volume. Examples of suitable solvents are hydrocarbons such as pentane, hexane, heptane, octane, decane, cyclohexane, methycyclohexane and cyclooctane aromatic hydrocarbons such as toluene, xylene or benzene. The temperature of the hydrogenation reaction may range, for example, from about 150 C. to about 500 C., preferably from about 250 C. to about 350 C. The hydrogenation reaction pressure may be, for example, in the range of 250-1000 psig hydrogen. The hydrogenated oligomeric polyalpha-olefins product is then recovered by conventional procedures. In the hydrogenated product, the double bonds formed in the oligomerization step have been hydrogenated so that the oligomer is a separate type of product. The hydrogenated oligomer may be used in the same manner as the unhydrogenated oligomer.

[0118] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group, such as wherein the organometallic complex is selected from the group consisting of:

##STR00027## ##STR00028##

and any combinations thereof.

[0119] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group, such as wherein the organometallic complex is:

##STR00029##

[0120] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group, such as wherein the organometallic complex is:

##STR00030##

[0121] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group, such as wherein the organometallic complex is:

##STR00031##

[0122] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group, such as wherein the organometallic complex is:

##STR00032##

[0123] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group, wherein the bridging group is bonded to two hydrocarbyl groups, each comprising a substituted or an unsubstituted cyclopentadienyl group, such as wherein the organometallic complex is:

##STR00033##

[0124] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene-bridging group bonded to two hydrocarbyl groups, each hydrocarbyl group comprising a substituted indenyl group, wherein the bridging group is bonded at the second position of each of the substituted indenyl group, such as wherein the organometallic complex is:

##STR00034##

[0125] Further examples of organometallic complexes comprising a substituted or an unsubstituted 2,2-biphenylene-bridging group and methods of making such organometallic complexes can be found, for example, in U.S. Pat. No. 9,938,360 to Vadake Kulangara et al.; U.S. Pat. No. 10,400,048 to Vadake Kulangara et al.; U.S. Pat. No. 11,040,995 to Kulangara et al.; and PCT application W02020/043815A1 to Hendriksen et al., each of which is incorporated by reference in its entirety. See also the synthesis methods disclosed in Synthesis, structure, and properties of chiral titanium and zirconium complexes bearing biaryl strapped substituted cyclopentadienyl ligands, W. W. Ellis et al, Organometallics 1993, 12, 4391-4401, and Biphenyl-bridged metallocene complexes of titanium, zirconium, and vanadium: syntheses, crystal structures and enantioseparation, M. E. Huttenloch et al., J. of Organometallic Chemistry 541 (1997), 219-232.

[0126] In various embodiments of the invention, the organic ligand L comprises a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group, such as wherein the organometallic complex is selected from the group consisting of:

##STR00035##

and any combinations thereof.

[0127] In various embodiments of the invention, the organic ligand L comprises a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group and one substituted or an unsubstituted indenyl group is bonded to the bridging group at the first position of the indenyl group, such as wherein the organometallic complex is selected from the group consisting of:

##STR00036##

and any combinations thereof.

[0128] In various embodiments of the invention, the organic ligand L comprises a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group, such as wherein the organometallic complex is:

##STR00037##

[0129] In various embodiments of the invention, the organic ligand L comprises a di-substituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group, such as wherein the organometallic complex is:

##STR00038##

[0130] In various embodiments of the invention, the organic ligand L comprises a disubstituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group, such as wherein the organometallic complex is:

##STR00039##

[0131] In various embodiments of the invention, the organic ligand L comprises a disubstituted alkyl-silyl bridging group, wherein the bridging group is bonded to two substituted or unsubstituted indenyl groups, wherein at least one substituted or an unsubstituted indenyl group is bonded to the bridging group at the second position of the indenyl group, such as wherein the organometallic complex is:

##STR00040##

[0132] In various embodiments of the invention, the organic ligand L comprises a disubstituted alkyl-silyl bridging group, wherein the bridging group is bonded to a tetra-alkyl substituted cyclopentadienyl group and to a 1-indenyl group, wherein the 1-indenyl group comprises a substituent at the second position wherein the substituent is selected from C.sub.3-C.sub.20 alkyl or C.sub.6-C.sub.20 aryl group, such as wherein the organometallic complex is selected from the group consisting of:

##STR00041##

and combinations thereof.

[0133] In various embodiments of the invention, the organic ligand L comprises a disubstituted alkyl-silyl bridging group, wherein the bridging group is bonded to a tetra-alkyl substituted cyclopentadienyl group and to a 1-indenyl group, wherein the 1-indenyl group comprises a substituent at the second position, such as wherein the substituent is selected from C.sub.3-C.sub.20 alkyl or C.sub.6-C.sub.20 aryl group, wherein the organometallic complex is

##STR00042##

[0134] In various embodiments of the invention, the organic ligand L comprises a disubstituted alkyl-silyl bridging group, wherein the bridging group is bonded to a tetra-alkyl substituted cyclopentadienyl group and to a 1-indenyl group, wherein the 1-indenyl group comprises a substituent at the second position, such as wherein the substituent is selected from C.sub.3-C.sub.20 alkyl or C.sub.6-C.sub.20 aryl group, wherein the organometallic complex is

##STR00043##

[0135] Further examples of organometallic complexes comprising a disubstituted alkyl-silyl bridging group and methods of making such organometallic complexes can be found, for example, in U.S. Pat. No. 11,040,995 to Kulangara et al.; and U.S. Pat. Publ. Nos. US2020/115478A1 to Friederichs et al.; US2020/199165A1 to Friederichs et al.; and US2021/115080A1 to Friederichs et al.; each of which is incorporated by reference in its entirety.

[0136] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 1, 2-phenylene bridging group bonded to a substituted or an unsubstituted 1-indenyl group and to a substituted or an unsubstituted 2-indenyl group; such as wherein the organometallic complex is:

##STR00044##

[0137] Further examples of organometallic complexes comprising a substituted or an unsubstituted 1, 2-phenylene bridging group and methods of making such organometallic complexes can be found, for example, in U.S. Pat. Publ. No. US2021/079032A1 to Hendriksen et al., which is incorporated by reference in its entirety.

[0138] In various embodiments of the invention, the organic ligand L comprises a bridging group comprising a substituted or an unsubstituted styryl moiety bonded to a substituent selected from a Group 16 element of the IUPAC Periodic Table and to a substituted cyclopentadienyl group, wherein the bridging group is bonded to a substituted cyclopentadienyl group at the alpha position of the styryl moiety; such as wherein the organometallic complex is selected from the group consisting of:

##STR00045##

and any combinations thereof.

[0139] In various embodiments of the invention, the organic ligand L comprises a bridging group comprising a substituted or an unsubstituted styryl moiety bonded to a substituent selected from a Group 16 element of the IUPAC Periodic Table and to a substituted cyclopentadienyl group, wherein the bridging group is bonded to a substituted cyclopentadienyl group at the alpha position of the styryl moiety; such as wherein the organometallic complex is

##STR00046##

[0140] In various embodiments of the invention, the organic ligand L comprises a bridging group comprising a substituted or an unsubstituted styryl moiety bonded to a substituent selected from a Group 16 element of the IUPAC Periodic Table and to a substituted cyclopentadienyl group, wherein the bridging group is bonded to a substituted cyclopentadienyl group at the alpha position of the styryl moiety; such as wherein the organometallic complex is

##STR00047##

[0141] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene bridging group bonded to a substituted or an unsubstituted indenyl group, and to a substituent selected from a Group 15 or a Group 16 element of the IUPAC Periodic Table, such as wherein the organometallic complex is:

##STR00048##

[0142] Further examples of organometallic complexes comprising a substituted or an unsubstituted 2,2-biphenylene bridging group bonded to a substituted or an unsubstituted indenyl group and methods of making such organometallic complexes can be found, for example, in PCT application W02021/048030A1 to Sainani et al., which is incorporated by reference in its entirety.

[0143] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 2,2-biphenylene group bonded to a substituent (A) and to a substituent (B), wherein substituent (A) is selected from a Group 15 element of the IUPAC Periodic Table and the substituent (B) is selected from a Group 15 or a Group 16 element of the RUPAC Periodic Table, further wherein the group 15 element of substituent (A) is covalently bonded to two sp.sup.2 hybridized carbon atoms, such as wherein the organometallic complex is:

##STR00049##

[0144] In various embodiments of the invention, the organic ligand L comprises a bridging group comprising at least one sp.sup.2 hybridized carbon atom bonded to two substituted or unsubstituted 2-indenyl groups, such as wherein the organometallic complex is selected from the group consisting of:

##STR00050##

and combinations thereof, wherein M is a transition metal having a valency of 4, wherein the metal M is selected from Ti, Zr, and Hf.

[0145] In various embodiments of the invention, the organic ligand L comprises a bridging group comprising at least one sp.sup.2 hybridized carbon atom bonded to two substituted or unsubstituted 2-indenyl groups, such as wherein the organometallic complex is

##STR00051##

wherein M is a transition metal having a valency of 4, wherein the metal M is selected from Ti, Zr, and Hf.

[0146] In various embodiments of the invention, the organic ligand L comprises a bridging group comprising at least one sp.sup.2 hybridized carbon atom bonded to two substituted or unsubstituted 2-indenyl groups, such as wherein the organometallic complex is

##STR00052##

wherein M is a transition metal having a valency of 4, wherein the metal M is selected from Ti, Zr, and Hf.

[0147] In various embodiments of the invention, the organic ligand L comprises a bridging group comprising at least one sp.sup.2 hybridized carbon atom bonded to two substituted or unsubstituted 2-indenyl groups, such as wherein the organometallic complex is

##STR00053##

wherein M is a transition metal having a valency of 4, wherein the metal M is selected from Ti, Zr, and Hf.

[0148] In various embodiments of the invention, the organic ligand L comprises a substituted or an unsubstituted 1,8-naphthalene-bridging group bonded to two substituted or unsubstituted 2-indenyl groups, such as wherein the organometallic complex is:

##STR00054##

[0149] In various preferred embodiments of the invention, the invention relates to a process for producing polyalpha-olefins by polymerizing one or more alpha-olefin monomers in presence of a catalyst composition comprising a reaction product of an organometallic complex and a cocatalyst. Preferably, the cocatalyst is a compound suitable of generating a cationic specie from the organic ligand L to form a non- or weakly coordinating anion.

[0150] In various embodiments of the invention, the cocatalyst is selected from an aluminium containing cocatalyst, a boron-containing cocatalyst, a zinc containing cocatalyst, or a combination thereof. Suitable aluminium-containing cocatalysts comprise aluminoxanes, alkyl aluminium compounds and aluminium-alkyl-chlorides. The aluminoxanes usable according to the present invention are well known and preferably comprise oligomeric linear and/or cyclic alkyl aluminoxanes represented by the formula: R.sup.3(AlR.sup.3O).sub.nAlR.sup.3.sub.2 for oligomeric, linear aluminoxanes and (AlR.sup.3O).sub.m for oligomeric, cyclic aluminoxanes; wherein n is 1-40, preferably n is 10-30; m is 3-40, preferably m is 3-30 and R.sup.3 is a C.sub.1 to C.sub.8 alkyl group and preferably a methyl group.

[0151] Some alternative examples of alumnimum containing cocatalyst include organoaluminum compounds include trimethylaluminum, triethylaluminium, triisopropylaluminum, tri-n-propylaluminum, triisobutylaluminum, tri-n-butylaluminum, triamylaluminium; dimethylaluminium ethoxide, diethylaluminium ethoxide, diisopropylaluminium ethoxide, di-n-propylaluminium ethoxide, diisobutylaluminium ethoxide and di-n-butylaluminium ethoxide; dimethylaluminium hydride, diethylaluminium hydride, diisopropylaluminium hydride, di-n-propylaluminium hydride, diisobutylaluminium hydride and di-n-butylaluminium hydride, tris-perfluorophenylaluminum.

[0152] Suitable boron-containing cocatalysts include trialkylboranes, for example trimethylborane or triethylborane and/or perfluoroarylborane and/or perfluoroarylborate-compounds, triphenylboron, tris-perfluorophenylboron, tetrakisperfluorophenylborate, triphenylcarboniumtetrakis perfluorophenylborate. Suitable zinc containing cocatalyst include diethyl zinc.

[0153] In various embodiments of the invention, the catalyst composition further comprises an activator, an anti-static agent, a scavenger. The term catalyst activator as used herein is to be understood as any compound, which can activate a single-site catalyst so that it is capable of oligomerizing the alpha-olefin monomers present in the feed stream. Preferably the catalyst activator is an alumoxane, a perfluorophenylborane and/or a perfluorophenylborate, preferably alumoxane, more preferably methylaluminoxane and/or modified methylaluminoxane. Activators that may be used include Lewis acid activators such as triphenylboron, tris-perfluorophenylboron, tris-perfluorophenylaluminum and the like and or ionic activators such as dimethylanilinium tetrakisperfluorophenylborate, triphenylcarboniumtetrakis perfluorophenylborate, dimethyl anilinium tetrakis perfluoro phenyl aluminate, and the like.

[0154] In various embodiments of the invention, the catalyst composition may further comprise a co-activator. A co-activator is a compound capable of alkylating the transition metal complex, such that when used in combination with an activator, an active catalyst is formed. Co-activators include alumoxanes such as methylalumoxane, modified alumoxanes such as modified methylalumoxane, and aluminum alkyls such trimethylaluminum, triisobutylaluminum, triethylaluminum, and tri-isopropylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tri-n-decylaluminum or tri-n-dodecylaluminum. Co-activators are typically used in combination with Lewis acid activators and ionic activators when the pre-catalyst is not a dihydrocarbyl or dihydride complex. In various embodiments of the invention, co-activators are also used as scavengers to deactivate impurities in feed or reactors. U.S. Pat. No. 9,409,834 B2 (line 39, column 21 to line 44, column 26) provides a detailed description of the activators and coactivators that may be used with a single site catalyst composition. The relevant portions of this patent are incorporated herein by reference in their entirety.

[0155] A scavenger is a compound that is typically added to facilitate oligomerization or polymerization by scavenging impurities. Some scavengers may also act as activators and may be referred to as co-activators. A co-activator which is not a scavenger may also be used in conjunction with an activator in order to form an active catalyst with a transition metal compound. In some embodiments, a co-activator can be pre-mixed with the transition metal compound to form an alkylated transition metal compound, also referred to as an alkylated catalyst compound or alkylated metallocene. To the extent scavengers facilitate the single site catalyst composition in performing the intended catalytic function, scavengers, if used, are sometimes considered as a part of the catalyst system.

[0156] U.S. Pat. No. 9,409,834 B2, line 37, column 33 to line 61, column 34 provides detailed description of scavengers useful in the process of the present invention for making PAO. The relevant portions in this patent on scavengers, their identities, quantity, and manner of use are incorporated herein in their entirety.

[0157] In various embodiments of the invention, the catalyst composition further comprises a support. For example, the support can be an organic or inorganic material and is preferably porous. Examples of organic material are cross-linked or functionalized polystyrene, PVC, cross-linked polyethylene. Examples of inorganic material are silica, alumina, silica-alumina, inorganic chlorides such as magnesium chloride, talc and zeolite. Mixtures of two or more of these supports may be used. The preferred particle size of the support is from 1 to 120 micrometres, preferably of from 20 to 80 micrometres and the preferred average particle size is from 40 to 50 micrometres.

[0158] In various embodiments of the invention, the process according to the present invention comprises co-feeding a mixture of alpha-olefin monomers along with the catalyst composition. The reaction may be carried out in batch, semi-batch or continuous, in a single or in multi-stage reactors. In a preferred embodiment, the mixture of catalyst composition and alpha olefin monomers are preferably fed into a first oligomerization reactor, where it is partially reacted and then into a second oligomerization reactor where the reaction may be allowed to continue to completion or where the reaction may be allowed to proceed further and then a subsequent mixture of a catalyst composition, alpha olefin monomers and oligomers are fed into a third oligomerization reactor, where the reaction is completed. Additional oligomerization reactors may be used in series.

[0159] It is preferred that each of the reactors may be equipped with a mixing or stirring means for mixing the feed and catalyst to provide intimate contact. In a more preferred embodiment, continuous stirred tank reactors (CSTRs) are used in series. The operation of CSTRs are per se known in the art. Also in an embodiment of the invention, no recycle of unconverted monomer is used. In various embodiments of the present invention, recycle of unconverted monomer is enabled.

[0160] Preferably the reaction conditions are controlled so as to cause effective conversion of the alpha-olefin monomers to the desired polyalpha-olefin products. In a preferred embodiment of the present invention, the reactor temperatures are retained between 25 C. and 150 C., preferably between 25 C. and 80 C. and residence time is regulated depending on the reactor type in sequence. For example, the residence time is about 1.5 to about 3 hours in reactor one and about 0.5 to about 1.5 hours in reactor 2, if used. The residence time in a third reactor, if used, would typically be from about 10 minutes to about 1 hour. The reaction is not particularly pressure-dependent and it is most economical to operate the reactors at a low pressure. In various embodiments of the invention, the one or more alpha-olefin monomer is oligomerized at a reactor pressure ranging between atmospheric pressure to about 50 psia.

[0161] Optionally, in various embodiments of the invention, a suitable amount of hydrogen may be introduced into the reactor in order to moderate the properties of the polyalpha-olefin so obtained. For example, in a further embodiment of the present invention, the polyalpha-olefin may be hydrogenated by a reaction with hydrogen gas in the presence of a catalytic amount (0.1 to 5 wt. %) of a hydrogenation catalyst. Details pertaining to hydrogenation may be similar to what has been described in the PCT application WO2021086926A1, incorporated herein as reference.

[0162] The alpha-olefin monomers may comprise an even number or an odd number of carbon atoms, preferably the alpha-olefin monomer has an even number of carbon atoms. In various embodiments of the invention, polyalpha olefins include monomers having 4-30 carbon atoms, preferably 6 to 18 carbon atoms, and most preferably 8 to 12 carbon atoms. In various embodiments of the invention, the one or more alpha-olefin monomer present in the feed stream is selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 4-methyl-1-pentene, 5-methyl-1-nonene, 3-methyl-1-pentene, 3,5,5-trimethyl-1-hexene, vinylcyclohexene, and any combinations thereof. In various embodiments of the invention, the one or more alpha-olefin monomer is oligomerized at a reactor temperature ranging between 25 C. to 150 C.

[0163] In various embodiments of the invention, the polyalpha-olefins produced by the present inventive process, comprises C.sub.20-24 dimers, C.sub.30-36 trimers, C.sub.40-48 tetramers, C.sub.50-60 pentamers, and C.sub.60+ heavies. The poly-alpha olefins produced from the process of the present invention may be used for preparing lubricant oil. For example, low viscosity crankcase lubricants consist of a mixture of C.sub.30 to C.sub.60 hydrocarbons with an average molecular weight (Mw) between 400-850. High viscosity lubricants have a higher Mw as high as 32K (32200), i.e., the equivalent of an oligomer consisting of 230 monomer decene units.

[0164] It should be understood that the embodiments and the aspects disclosed herein are not mutually exclusive and such aspects and embodiments can be combined in any way. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to yield essentially the same results.