Method of controlling kinematic viscosity of polyalphaolefin

Abstract

The invention relates to a method of the oligomerization of C6 and above olefin monomer whereby, at a fixed monomer/Al halide mole ratio, polyalphaolefins having desirable kinematic viscosities are prepared by controlling the oligomerization temperature. The oligomerization is carried out in presence of an oligomerizing catalyst comprising of aluminum halide and a promoter, and oligomerizing temperatures of about 10° C. to about 120° C.

Claims

1. A process for controlling kinematic viscosity of a polyalphaolefin in a range of 1-70 centistokes at 100° C., the process comprising: oligomerizing C6 and above olefin monomers in presence of an aluminium halide, a promoter, and a solvent to obtain the polyalphaolefin; wherein the promoter is water, an alcohol, a ketone, an ether, or any combination thereof; wherein the kinematic viscosity of the polyalphaolefin is controlled by adjusting oligomerization temperature at a fixed mole ratio of olefin monomer and the aluminium halide, and wherein the mole ratio of the olefin monomer to the aluminium halide is from 10 to 500.

2. The process as claimed in claim 1, wherein the olefin monomer is selected from the group consisting of 1-decene, 1-dodecene, 1-octene and a mixture thereof.

3. The process as claimed in claim 1, wherein a mole ratio of the aluminium halide to the promoter is from 1 to 10.

4. The process as claimed in claim 1, wherein the promoter is iso-butyl alcohol.

5. The process as claimed in claim 1, wherein the olefin monomers and the solvent have a moisture content less than 20 ppm.

6. The process as claimed in claim 1, wherein an oligomerization temperature is in a range from 10° C. to 150° C.

7. The process as claimed in claim 1, wherein the oligomerization temperature is in a range of 25° C. and 90° C.

8. The process as claimed in claim 1, wherein a residence time during the oligomerization is in a range of 0.5 to 8 hours.

9. The process as claimed in claim 1, wherein the solvent is selected from C5 to C19 paraffinic hydrocarbons.

10. The process as claimed in claim 1, wherein a conversion from the monomer to the polyalphaolefin is in a range of 95% to 98%.

11. The process as claimed in claim 1, wherein the oligomerizing C6 and above olefin monomers produces C20-24 dimers, C30-36 trimers, C40-48 tetramers, C50-60 pentamers, and C60+ heavies.

Description

DESCRIPTION OF THE INVENTION

(1) The invention relates to a method of the oligomerization of C6 and above olefin monomer whereby, at a fixed monomer/Al halide mole ratio, polyalphaolefins having desirable kinematic viscosities are prepared by controlling the oligomerization temperature. The oligomerization is carried out in presence of an oligomerizing catalyst comprising of aluminum halide and a promoter, and oligomerizing temperatures of about 10° C. to about 120° C.

(2) A method of oligomerization of C.sub.6 and above olefin monomer to polyalphaolefin having desirable kinematic viscosity is provided. In an embodiment, the process comprising of the step of oligomerizing in the presence of an aluminum halide and a promoter, wherein the mole ratio of the monomer to the aluminum halide is from 10 to 500, preferably from 10 to 350.

(3) In another embodiment, the invention relates to a process for oligomerization of C6 and above olefin monomer to polyalphaolefin having desirable kinematic viscosity, the process comprising of the step of oligomerizing in the presence of an aluminum halide and a promoter, wherein the aluminum halide is selected from the compounds having the formula as R.sub.3-nAlX.sub.n wherein R is a hydrocarbyl group (i.e., an alkyl group), X is a halide and n=0 to 3. In an embodiment, halide can be chloride, bromide or iodide, preferably chloride or bromide. In an embodiment, the aluminum halide is aluminum chloride or aluminum bromide.

(4) In an embodiment, C.sub.6 and above olefin monomer can be olefins of the range C.sub.6 to C.sub.14, wherein, mixtures of C.sub.6 to C.sub.14 olefin monomer can be used. In another embodiment, recycle or redistilled olefin monomer can be used.

(5) In an embodiment, the invention relates to a process for oligomerization of and above olefin monomer to polyalphaolefin having desirable kinematic viscosity, the process comprising of the step of oligomerizing in the presence of an aluminum halide and a promoter, wherein the mole ratio of the aluminum halide to the promoter is from 1 to 10, preferably from 1 to 5.

(6) In an embodiment, the promoter is selected from the compounds consisting of water, an alcohol, a carboxylic acid, an ester, a ketone, an ether, a halogenated hydrocarbon, or any combination thereof. In another embodiment, the promoter is selected from the compounds consisting of water, an alcohol, an ester, a ketone or any combination thereof. In an embodiment, the promoter is iso-butyl alcohol.

(7) The inventors were surprised to find that by controlling the oligomerization temperature, at a fixed monomer/Al weight ratio, polyalphaolefins having desirable kinematic viscosities are prepared. In an embodiment, the oligomerization temperature is in the range from 10° C. to 150° C., although temperatures outside this range can be utilized. The preferred oligomerization temperature is 10° C. to 120° C. For non-adiabatic oligomerizations, to maintain steady state conditions, heat transfer capability may be necessary.

(8) Further the inventors were surprised to find that addition of promoter along with the olefin monomer not only improves bromine number of the resultant polyalphaolefin but also controls the exothermicity of the oligomerization. Hence, the reaction proceeds in control manner, leading to lesser probability of hot spots or run away.

(9) In general, the residence time over which the oligomer product is formed is the time where desired conversions are achieved. In an embodiment, the residence time during oligomerization of about 0.5 to 8 h.

(10) For any oligomerizations carried out using aluminium halides, the reactants as well as the apparatus/equipments should be poison free especially air and moisture. Hence for that all the apparatus/equipments are heated and dried either in vacuum or nitrogen while monomers and solvents are distilled, passed through dessicant columns or stored over dessicants. Manipulation before and during oligomerizations for maintaining inert conditions and atmospheres are carried out wherever necessary.

(11) In an embodiment, no solvent is used during the oligomerization. In another embodiment, the choice of solvent can be related to the oligomerization temperature. In an embodiment, the solvent can be selected from C.sub.5 to C.sub.19 paraffinic hydrocarbons.

(12) After the oligomerization is complete, the conversion from the monomer to oligomer is normally greater than 95%. The oligomerization is stopped by addition of water or alcohol, followed by a catalyst removal step, such as an aqueous wash or filtration, absorption or centrifugation. The next step is removal of monomer, promoter and low boiling oligomers through distillation.

(13) The oligomeric product is essentially hydrogenated but can be optionally either before or after distillation. The hydrogenation is carried out using metallic catalyst and hydrogen. Normally, bromine number below 5 and more preferably below 2 will produce an oligomer with excellent oxidation stability. In an embodiment, the resulting product is typically hydrogenated to saturate the oligomers to provide a product having a desired viscosity, for example 40 cSt or 100 cSt at 100° C.

(14) Depending on the viscosity, the product of the oligomerization typically 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.

(15) One of the features of the invention is that the oligomerized product can be used in variety of application for example, as base oils in lubricants, additives for various compositions, viscosity index improvers, dispersants etc.

(16) All monomers and solvents were used as obtained and contained moisture less than 20 ppm. All chemicals based on aluminium halide were handled under nitrogen atmosphere and used as obtained.

(17) AlCl.sub.3 based chemistry is extensively used to produce PAO. The variation of reactant mol ratios, effect of varying the substituents or solvents have been extensively studied. In this invention, at fixed monomer/Al mole ratio, by varying the temperature, PAO of different viscosities are prepared. This itself is unique especially for preparing low viscosities PAO as each batch can be tuned to produce, e.g., PAO4 in high concentration. Each batch will produce PAO from dimers to pentamers which can be separated by distillation.

(18) The kinematic viscosity (sometimes also called the momentum diffusivity), defined as the ratio of the viscosity μ to the density of the fluid ρ. It is usually denoted by the Greek letter nu (ν) and has dimension (length).sup.2/time.

(19) SVM 3000 Stabinger Viscometer is used to measure the dynamic viscosity and density of oils and fuels according to ASTM D7042-21. From said dynamic viscosity results/values, the SVM 3000 viscometer automatically calculates the kinematic viscosity and delivers measurement results which are equivalent to ISO 3104 or ASTM D445-19a. The dynamic viscosity is the essential value for evaluating the lubricating behavior.

(20) Viscosity index is a dimensionless number and is used to investigate the change in the viscosity at different temperatures. The greater the viscosity index (VI), the smaller the change in fluid viscosity for a given change in temperature, and vice versa. The viscosity index is calculated from the kinematic viscosity at different temperature ranges.

(21) In an aspect of the present invention, the present invention discloses a process for controlling kinematic viscosity of a polyalphaolefin below 70 centistokes, the process comprising the steps of oligomerizing C6 and above olefin monomers in the presence of an aluminum halide, a promoter and optionally, a solvent to obtain a polyalphaolefin; wherein, the kinematic viscosity of the polyalphaolefin is controlled by adjusting oligomerization temperature at a fixed monomer and aluminium halide mole ratio.

(22) In an aspect of the present invention, the present invention discloses a process for controlling kinematic viscosity of a polyalphaolefin in a range of 1-70 centistokes, the process comprising the steps of: oligomerizing C6 and above olefin monomers in the presence of an aluminum halide, a promoter and optionally, a solvent to obtain a polyalphaolefin; wherein, the kinematic viscosity of the polyalphaolefin is controlled by adjusting oligomerization temperature at a fixed monomer and aluminium halide mole ratio.

(23) According to a feature of the present invention, the olefin monomer or monomer is selected from the group comprising of 1-decene, 1-dodecene, 1-octene and any mixture thereof.

(24) According to a feature of the present invention, mole ratio of the olefin monomer or monomer to the aluminum halide is from 10 to 500, more preferably from 10 to 350, most preferably from 40 to 300.

(25) According to a feature of the present invention, mole ratio of the aluminum halide to the promoter is from 1 to 10, preferably from 1 to 5.

(26) According to a feature of the present invention, the promoter is selected from the group/compounds consisting of water, an alcohol, a carboxylic acid, an ester, a ketone, an ether, a halogenated hydrocarbon, or any combination thereof.

(27) According to a feature of the present invention, the promoter is iso-butyl alcohol.

(28) According to a feature of the present invention, the olefin monomers or monomers and the solvents have moisture content less than 20 ppm.

(29) According to a feature of the present invention, the oligomerization temperature is in the range from 10° C. to 150° C.

(30) According to a feature of the present invention, the oligomerization temperature is 25° C. and 90° C.

(31) According to a feature of the present invention, residence time during the oligomerization is in the range of 0.5 to 8 hours.

(32) According to a feature of the present invention, the solvent is selected from C5 to C19 paraffinic hydrocarbons.

(33) According to a feature of the present invention, conversion from the monomer to polyalphaolefin is greater than 95%.

(34) According to a feature of the present invention, the oligomerization comprises C20-24 dimers, C30-36 trimers, C40-48 tetramers, C50-60 pentamers, and C60+ heavies.

(35) According to a feature of the present invention, the kinematic viscosity decreases on increasing the monomer and the aluminium halide mole ratio.

(36) In another aspect of the present invention, the present invention discloses a process for preparing a polyalphaolefin, the process comprising the steps of: a) oligomerizing one or more alpha olefin monomers having C6-C14 carbon atoms under an inert atmosphere in the presence of an aluminum halide, a promoter and optionally, a solvent to obtain an oligomeric product in a reaction mass; wherein the aluminum halide is selected from the compounds having the formula as R.sub.3-nAlX.sub.n; wherein R is a hydrocarbyl group or an alkyl group, X is a halide, and n=0 to 3; wherein the halide is selected from chloride or bromide; b) stopping the oligomerization of the monomers in the reaction mass by addition of water or alcohol; c) removing the aluminum halide from the reaction mass by aqueous wash or filtration or absorption or centrifugation or any combination thereof; d) separating unconverted monomer, the promoter and the oligomeric product from the reaction mass through distillation; e) hydrogenating the oligomeric product to saturate oligomers to provide polyalphaolefin; wherein kinematic viscosity of the polyalphaolefin is below 70 centistokes.

(37) In another aspect of the present invention, the present invention discloses a process for preparing a polyalphaolefin, the process comprising the steps of a) oligomerizing C6 and above olefin monomers under an inert atmosphere in the presence of an aluminum halide, a promoter and optionally, a solvent to obtain an oligomeric product in a reaction mass; wherein the aluminum halide is selected from the compounds having the formula as R.sub.3-nAlX.sub.n; wherein R is a hydrocarbyl group or an alkyl group, X is a halide, and n=0 to 3; wherein the halide is selected from chloride or bromide; b) stopping the oligomerization of the monomers in the reaction mass by addition of water or alcohol; c) removing the aluminum halide from the reaction mass by aqueous wash or filtration or absorption or centrifugation or any combination thereof; d) separating unconverted monomer, the promoter and the oligomeric product from the reaction mass through distillation; e) hydrogenating the oligomeric product to saturate oligomers to provide polyalphaolefin; wherein kinematic viscosity of the polyalphaolefin is below 70 centistokes.

(38) In a feature of the present invention, the hydrogenation is carried out using metallic catalyst and hydrogen.

(39) In a feature of the present invention, conversion from the monomer to oligomer is greater than 95%.

(40) In another aspect of the present invention, the present invention discloses a process for preparing a polyalphaolefin, the process comprising the steps of a) oligomerizing C6 and above olefin monomers under an inert atmosphere in the presence of an aluminum halide, a promoter and optionally, a solvent to obtain an oligomeric product, i.e., polyalphaolefin; wherein kinematic viscosity of the polyalphaolefin is below 70 centistokes.

(41) Table 1 showing the effect of temperature on the viscosity of the PAO at fixed Monomer/Al ratios

(42) TABLE-US-00001 KV@100° C. Oligomerization Oligomerization Monomer/ Temp Temp Al ratio 25° C. 90° C. % Conversion 10 61.1 30.9 95 25 60.1 30.2 97 48 53.9 25.4 98 83 45.6 23.6 98 100 30.4 8.1 96 165 23.4 5.8 96 282 12.1 4.5 95 450 8.6 3.2 96

(43) Table 2 showing the effect of fixing the Monomer/Al ratios during runaway reaction

(44) TABLE-US-00002 KV@100° C. Oligomerization Runaway Reaction Monomer/ Temperature Temperature Al ratio 25° C. 100-110° C. % Conversion 10 61.1 12.9 95 83 45.6 10.9 98 100 30.4 6.5 96 165 23.4 4.0 96 282 12.1 2.1 95

EXAMPLES

(45) The present invention is exemplified by following non-limiting examples:

Example 1

(46) In 2 L CSTR, 250 ml of hexane, 13.6 g of AlCl.sub.3 (0.10 mol) and 4.0 mL iso-butanol was added and stirred for 15 min. The oligomerization temperature was set to 25° C. Addition of 1-decene (C10/AlCl.sub.3 mol ratio=83) was started at flow rate of 8.4 ml/min for 3 hours. After complete addition of monomer, the solution was kept on stirring for additional 1 hour. 100 ml of deionized water was added to quench the reaction followed by another water washing. The subsequent oil obtained was kept on sodium sulphate overnight and filtered. After removal of monomer, the oil was hydrogenated using Nickel on Kieselguhr catalyst. The hydrogenated oil had KV of 45.6 cSt@100° C., VI of 147.

Example 2

(47) The procedure for oligomerization followed was same as described in Example 1 but instead, the oligomerization temperature was set to 90° C. The hydrogenated oil had KV of 23.5 cSt@100° C., VI of 147.

Example 3

(48) The procedure for oligomerization followed was same as described in Example 1 but instead, the C10/AlCl.sub.3 mol ratio was kept as 282. The hydrogenated oil had KV of 12.1 cSt@100° C., VI of 142.

Example 4

(49) The procedure for oligomerization followed was same as described in Example 1 but instead, the C10/AlCl.sub.3 mol ratio was kept as 282 and the oligomerization temperature was set to 90° C. The hydrogenated oil had KV of 4.5 cSt@100° C., VI of 142.

Example 5

(50) The procedure for oligomerization followed was same as described in Example 1 but instead, the C10/AlCl.sub.3 mol ratio was kept as 165. The hydrogenated oil had KV of 23.4 cSt@100° C., VI of 142.

Example 6

(51) The procedure for oligomerization followed was same as described in Example 1 but instead, the C10/AlCl.sub.3 mol ratio was kept as 165 and the oligomerization temperature was set to 90° C. The hydrogenated oil had KV of 5.8 cSt@100° C., VI of 144.

Example 7

(52) The procedure for oligomerization followed was same as described in Example 1 but instead, the C10/AlCl.sub.3 mol ratio was kept as 100. The hydrogenated oil had KV of 30.4 cSt@100° C., VI of 142.

Example 8

(53) The procedure for oligomerization followed was same as described in Example 1 but instead, the C10/AlCl.sub.3 mol ratio was kept as 100 and the oligomerization temperature was set to 90° C. The hydrogenated oil had KV of 8.1 cSt@100° C., VI of 141.

Example 9

(54) The procedure for oligomerization followed was same as described in Example 1 but instead, the monomer/AlCl.sub.3 mol ratio was kept as 48 and the monomer was 1-dodecene. The hydrogenated oil had KV of 53.9 cSt@100° C., VI of 147.

Example 10

(55) The procedure for oligomerization followed was same as described in Example 1 but instead, the monomer/AlCl.sub.3 mol ratio was kept as 48 and the monomer was 1-dodecene, and the oligomerization temperature was set to 90° C. The hydrogenated oil had KV of 25.4 cSt@100° C., VI of 142.

TECHNICAL ADVANTAGES OF THE INVENTION

(56) The present invention has the following advantage over the prior arts: Using fixed monomer/Al ratios, can control viscosity of the resultant PAO by varying the temperature. Particularly, useful advantage in low viscosity PAO preparation where any variation in catalyst amount would not lead to batch failure. Addition of promoter to the feed controls the exotherm during the oligomerization.