Process for the production of end-saturated polyalfaolefin lubricants

Abstract

This invention relates to novel and improved catalyst and catalysts systems for the oligomerization of the higher olefins, which produce lubricants having improved properties, such as end-saturated oligomer chains which are needless to hydrogenation process, low kinematic viscosity and/or high viscosity index, low pour point, and high flash point lubricants.

Claims

1-15. (canceled)

16. A process to produce end-saturated PAOs comprising contacting at least one olefin with a catalyst system at oligomerization conditions to produce end-saturated PAOs; wherein the catalyst system comprises a) a compound, b) an activator, and c) a chain transfer agent with formula ZnR.sub.2, wherein R is selected from ethyl and methyl; wherein that compound is of formula (I): ##STR00008## wherein M is selected from titanium, zirconium, hafnium, and rutherfordium; wherein X.sub.1 and X.sub.2 are independently selected from a C.sub.1 to C.sub.20 hydrocarbyl radical and halogen, or X.sub.1 and X.sub.2 join together to form a C.sub.4 to C.sub.12 cyclic or polycyclic ring structure, provided, R.sub.1, R.sub.2, R.sub.4, R.sub.7, R.sub.9, R.sub.10, R.sub.11, R.sub.12, R.sub.13, and R.sub.14 are independently selected from a hydrogen and a C.sub.1 to C.sub.10 hydrocarbyl group; wherein R.sub.3, R.sub.5, R.sub.6, and R.sub.8 are independently a C.sub.1 to C.sub.40 hydrocarbyl group; and wherein the activator is an alumoxane compound or tripropylammoniumtetrakis(perfluoronaphthyl)borate.

17. The process of claim 16, wherein the oligomerization condition comprises a temperature of from about −25° C. to about 150° C., a pressure from about 0.1 MPa to about 20 MPa, and a time period from about 5 minutes to about 36 hours.

18. The process of claim 16, wherein the oligomerization condition comprises one or more solvents selected from isobutane, butane, pentane, isopentane, hexanes, isohexane, heptane, octane, dodecane, and mixtures thereof; cyclic and alicyclic hydrocarbons, and aromatics.

19. The process of claim 16, wherein the olefin is selected from 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 1-heneicosene, and 1-docosene.

20-21. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1. .sup.13C-NMR spectrum of N,N′-bis(2-hydroxy-3,5-di-tert-butylphenyl) 4,5-dimethyl-1,2-phenylenediamine, [L].

[0038] FIG. 2. .sup.1H-NMR spectrum of N,N′-bis(2-hydroxy-3,5-di-tert-butylphenyl) 4,5-dimethyl-1,2-phenylenediamine, [L].

[0039] FIG. 3. .sup.13C-NMR spectrum of [Ti{2,2′-(OC.sub.6H.sub.2-4,6-.sup.tBu.sub.2).sub.2NHMePhMeNH}(Cl.sub.2], [Cat].

[0040] FIG. 4. .sup.1H-NMR spectrum of [Ti{2,2′-(OC.sub.6H.sub.2-4,6-.sup.tBu.sub.2).sub.2NHMePhMeNH}(Cl.sub.2], [Cat].

[0041] FIG. 5. .sup.13C-NMR spectrum of prepared oligomer, Zn/Ti=0.

[0042] FIG. 6. .sup.1H-NMR spectrum of prepared oligomer, Zn/Ti=0.

[0043] FIG. 7. .sup.13C-NMR spectrum of prepared oligomer, Zn/Ti=30.

[0044] FIG. 8. .sup.1H-NMR spectrum of prepared oligomer, Zn/Ti=30.

[0045] FIG. 9. .sup.13C-NMR spectrum of prepared oligomer, Zn/Ti=90.

[0046] FIG. 10. .sup.1H-NMR spectrum of prepared oligomer, Zn/Ti=90.

[0047] FIG. 11. .sup.13C-NMR spectrum of prepared oligomer, Zn/Ti=120.

[0048] FIG. 12. .sup.1H-NMR spectrum of prepared oligomer, Zn/Ti=120.

EXAMPLES

Example 1

Synthesize of N,N′-bis(2-hydroxy-3,5-di-tert-butylphenyl) 4,5-dimethyl-1,2-phenylenediamine, [L]

[0049] 4,5-dimethyl-1,2-phenylenediamine (0.153 g; 1.125 mmol) in 2 mL acetonitrile was introduced slowly to a solution of 3,5-di-tert-butylcatechol (0.50 g; 2.25 mmol) in acetonitrile (5 mL) in the presence of air. After heating to reflux at 75° C. for 4 h, the reactor was cooled to room temperature and continued for 8 h during which time period a gray precipitate of [L] was prepared which was separated by filtration, washed three times with dried n-hexane, and air-dried. The N,N′-bis(2-hydroxy-3,5-di-tert-butylphenyl) 4,5-dimethyl-1,2-phenylenediamine, [L] was characterized by .sup.13C-NMR spectrum (FIG. 1) and .sup.1H-NMR spectrum (FIG. 2).

##STR00006##

Example 2

Synthesize of [Ti(2,2′-(OC.SUB.6.H.SUB.2.-4,6-.SUP.t.Bu.SUB.2.).SUB.2.NHMePhMeNH)(Cl.SUB.2.], [Cat]

[0050] Titanium(IV) chloride (53 μL; 0.483 mmol) was added dropwise to 263 mg (0.483 mmol) of L in 5 mL of toluene at −30° C. The reactor was heated to 25° C. and stirred for a further 3 h. The solvent was removed under vacuum, and the obtained precipitate was crystallized with 10 mL of pentane. Upon standing at −30° C., a black precipitate resulted, which was filtrated and dried to give final product. The [Ti{2,2′-(OC.sub.6H.sub.2-4,6-.sup.tBu.sub.2).sub.2NHMePhMeNH}(Cl.sub.2], [Cat] was characterized by .sup.13C-NMR spectrum (FIG. 3) and .sup.1H-NMR spectrum (FIG. 4).

##STR00007##

Example 3

Synthesis of Oligomerization Products

[0051] After successful synthesis of the ligand and catalyst, it was employed in the coordinative chain transfer oligomerization of 1-decene using ZnEt.sub.2 as chain transfer agent and methylaluminoxane (MAO) as cocatalyst. Synthesis of 1-decene oligomers with prepared Cat and employed catalyst compound employing chain coordination transfer oligomerization (CCTO) technique:

[0052] 10 mL (53 mmol) of dried 1-decene in the presence of 15 mL toluene as a solvent and appropriate amount of ZnEt.sub.2 as chain transfer agent were injected into two-necked 100 mL flask. To this, 5 mL of MAO (10 wt. % in toluene, 7.56×10.sup.−3 mol) was introduced. The oligomerization reaction was started by the injection of a 1.51×10.sup.−3 M solution (7.56×10.sup.−6 mol, prepared by dissolving 0.005 g of synthesized catalyst in 5 mL of toluene) of prepared catalyst at 80° C. After 2 h, the reaction was terminated by the addition of 100 mL of a 5 wt. % HCl/methanol solution.

[0053] Obtained product was centrifuged to separate possible Zn-based solids which had been formed during the reaction. Then, the solution was washed three times with 3 wt. % solution of NaOH/H.sub.2O. The unreacted monomers were extracted by high vacuum (−0.8 bar) distillation at 200° C.

[0054] This method in example was used with different chain transfer agent/catalyst ratio (mol/mol) for obtaining products 1, 2, 3, and 4 from ZnEt.sub.2/Cat ratio of 0, 30, 90, and 120, respectively. Then, the products were washed and distilled to remove lights. The products had the properties given in Table 1.

TABLE-US-00001 TABLE 1 Results of 1-decene oligomerization at different oligomerization conditions.sup.a Zn/Ti Time Yield M.sub.n Entry (mol:mol) (min) (%) Activity.sup.b (g/mol) PDI 1 0.0 120 91.9 449.73 1162 1.42 2 30 120 86.4 423.28 938 1.22 3 90 120 79.7 390.21 630 1.15 4 120 120 74.3 363.75 525 1.31 .sup.aOligomerization conditions: [Cat] = 5.0 mg, 1-decene = 53 mmol, Al/Ti = 1000, T = 80° C.; .sup.b(g oligomer)/mmol cat .Math. h)

[0055] Then, the tacticity and end unsaturation type of the synthesized oligomers were examined by .sup.13C-NMR and .sup.1H-NMR spectroscopies, respectively. The .sup.13C-NMR and .sup.1H-NMR spectra of prepared oligomers at Zn/Ti=0, 30, 90 and 120 are shown in FIG. 5 to FIG. 12 and the data are collected in Table 2. It was found that at Zn/Ti>90 mol/mol, unsaturation content approaches to zero. It means that at these ZnEt.sub.2 contents, fully saturated PAOs are achieved.

TABLE-US-00002 TABLE 2 Pentad distributions and unsaturated structures in the synthesized oligomers Pentad distribution.sup.a (%) Unsaturated structures Entry mm mr rr % Vn % 2 Vn % 3 Vn % Vd 1 0 0 ≅100 ≅0 38.2 53.6 8.2 2 16 23 61 ≅0 31.9 51.3 16.8 3 27 41 32 — — — — 4 31 12 57 — — — — (mm = isotactic, mr = atactic, and rr = syndiotactic).

[0056] The pour point and viscosity analyses of the resulted PAOs are gathered in Table 3. According to the results, employed CCTO technique yields PAOs with 3.5<KV.sup.100<7.0 cSt.

TABLE-US-00003 TABLE 3 The pour point, viscosity and GC results of synthesized oligomers GC Viscosity % % Pour KV.sup.100 KV.sup.40 % % Tetra- >Tetra- point Run (cSt) (cSt) VI <Trimer Trimer mer mer (° C.) 1 7.9 46.0 131.7 6 5 35 54 −48 2 6.8 37.1 134.5 4 6 36 54 −55 3 4.2 17.3 159.7 3 57 28 12 −50 4 3.5 13.5 148.7 9 52 31 8 −59

[0057] To increase KV.sup.100 of the PAO and get higher viscosity grades, oligomerization was conducted at lower temperatures of 75 and 70° C. At these oligomerization conditions, PAO6 and PAO8 were obtained with good yields, too (Table 4).

TABLE-US-00004 TABLE 4 Results of 1-decene oligomerization at different oligomerization conditions.sup.a T Zn/Ti Time Yield M.sub.n Entry (° C.) (mol:mol) (min) (%) Activity.sup.b (g/mol) PDI 5 75 90 120 76.9 380.92 855 1.22 6 70 90 120 74.8 370.51 1221 1.31 .sup.aOligomerization conditions: [Cat] = 5.0 mg, 1-decene = 53 mmol, Al/Ti = 1000 mol/mol; .sup.b(g oligomer)/mmol cat .Math. h)

[0058] The produced PAO6 and PAO8 oligomers had high VI and low pour point (Table 5) which are comparable with commercial PAO6 and PAO8.

TABLE-US-00005 TABLE 5 The pour point, viscosity and GC results of synthesized oligomers GC Viscosity % % Pour KV.sup.100 KV.sup.40 % % Tetra- >Tetra- point Run (cSt) (cSt) VI <Trimer Trimer mer mer (° C.) 5 5.8 28.1 144.9 6 14 46 33 −53 6 8.1 41.1 147.2 3 12 31 54 −55

[0059] They also have fully saturated nature, which is beneficial for their oxidative stability.

[0060] In summary, the produced polyalphaolefins have kinematic viscosity at 100° C. (KV.sup.100 in the range of 2-8 cSt, viscosity index (VI) above 130, and pour points in the range of −40 and −60° C. The prepared hydrocarbon lubricants can be based on either 1-decene or 1-octene monomer or even the mixture of them. The productivity of the process is at least 363.75 g of total product per mmol of transition metal and nearly 92% of monomer is converted to the PAO product in two hours.