Low viscosity and medium-high viscosity polyalphaolefin base oils, and methods of making and using the same

Abstract

The present application provides a kind of low viscosity and medium-high viscosity poly-alpha-olefin base oil and its preparation method and purposes, the preparation method includes alpha-olefin dimer and haloalkane, in the mediation of alkyl metal halide, hydrogen-alkylation reaction is carried out in inert atmosphere.The present application provides a new route of low viscosity and medium-high viscosity poly-alpha-olefin base oil synthesis, the present application effectively utilizes the dimer byproduct generated in poly-alpha olefin production process, improves its use value, does not need to use toxic catalyst, reduces the damage to equipment, and will not cause environmental pollution, total hydrocarbon yield can reach more than 90%, the content of low viscosity poly-alpha-olefin base oil can reach more than 50%, and the oligomer generated in the preparation process can be used as medium-high viscosity base oil, reduces the waste of product;The base molecular structure of synthesis can be accurately controlled by reaction substrate, so as to prepare PAO of different viscosity.

Description

Technical Field

[0001] This invention relates to the field of base oil preparation technology, and in particular to a low-viscosity and medium-high viscosity polyalphaolefin base oil, its preparation method and uses. Background Technology

[0002] Polyalphaolefins (PAOs) are synthetic base oils obtained by polymerization of long-chain alpha-olefins under the action of Lewis acids (such as BF3 and AlCl3) or Ziegler-Natta catalysts. They are key raw materials for lubricants in high-end equipment such as engines, high-speed trains, and wind power systems. In recent years, with the rapid development of new energy and electric vehicle sectors, there has been a growing demand for ultra-low viscosity polyalphaolefins (PAOs), such as PAO2 (viscosity 1.6–2 mm at 100℃). 2 / s, the main components are C20), PAO3.5 (viscosity 3.5mm at 100℃). 2 The demand for PAO2 (primarily C30) base oils is rapidly increasing. As a fully synthetic saturated hydrocarbon base oil, PAO2 has achieved large-scale application in data center immersion cooling and energy storage system thermal management due to its significant cost advantage compared to fluorinated fluids and its high open-cup flash point. In the field of new energy vehicle thermal management, PAO3.5, with its excellent low-temperature fluidity (pour point below -60°C), moderate boundary lubrication characteristics, and ASIL-D electrical safety rating, is becoming the preferred base oil solution for full-area cooling of power battery packs, integrated lubrication of electric drive systems, and integrated immersion cooling of automotive electronic components. It is worth noting that in the traditional internal combustion engine lubrication field, reducing lubricant viscosity has become an important technical path to improve energy efficiency. Reducing oil viscosity can effectively reduce resistance losses between system friction pairs, thereby significantly improving fuel economy and reducing energy consumption. This technological trend has directly driven the rapid development of engine oil products towards lower viscosity, making PAO3.5 the preferred base oil for ultra-low viscosity 0W-20 and 0W-15 engine oils.

[0003] Traditionally, these two viscosity grades of polyalphaolefin (PAO) base oils are primarily produced through polymerization using boron trifluoride (BF3) catalysis. However, BF3, as a typical Lewis acid catalyst, has significant drawbacks: its strong corrosiveness can easily damage reaction equipment, and its volatile gases are toxic, posing environmental risks. Therefore, developing green alternative catalytic systems has become a research hotspot in this field. Among numerous candidate catalytic systems, metallocene catalysts have attracted considerable attention due to their well-defined active sites and tunable molecular structures. However, metallocene catalytic systems generate 5%-30% dimers during PAO polymerization. These oligomers, possessing only monomethyl side chains, exhibit insufficient isomerization, resulting in significantly deteriorated low-temperature flow properties (pour point > -20°C). This makes them unsuitable for direct use in lubricating oil base oils and often considered waste generated during PAO production, resulting in low market value. This limitation restricts their practical application and leads to product waste.

[0004] US Patent 11078308B2 selectively prepared α-olefin dimers using a metallocene catalyst. These dimers were then reacted with monomeric α-olefins in the presence of boron trifluoride to prepare PAO 3.5 base oil in high yields (>90%). US Patent 8143467B2 used 1-ethyl-3-methylimidazolium chloroaluminate ionic liquid as a polymerization catalyst and 1-decene dimer C20 as a starting material to synthesize a product with a viscosity grade of 10 mm. 2 The product of / s.

[0005] The boron trifluoride used in the above patents is highly toxic to the environment and has more stringent requirements for equipment, while ionic liquids can only synthesize medium-viscosity PAO products.

[0006] In summary, the existing technology has the following shortcomings:

[0007] (1) In the process of preparing polyalphaolefins from alphaolefins by metallocene catalysis, alphaolefin dimers are generated. Due to their low molecular weight, poor fluidity and viscosity, they are difficult to use as base oils, have low utilization value, limit their practical application, and cause waste of products.

[0008] (2) The use of toxic catalysts in the preparation of low-viscosity polyalphaolefin base oils causes equipment damage and environmental pollution.

[0009] (3) Existing technologies are prone to producing unsaturated olefin products during the synthesis of polyα-olefin base oils, which requires dangerous hydrogenation processes, and the oligomers generated during the preparation process cannot be effectively utilized in industry.

[0010] (4) The oligomers produced in the process of synthesizing polyα-olefin base oil by existing technologies are often mixtures with unclear molecular structures. Summary of the Invention

[0011] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide low-viscosity and medium-high viscosity polyalphaolefin base oils, their preparation methods and uses, to improve the problems of ineffective utilization of alpha olefin dimers and equipment damage, environmental pollution or uncontrollable products in the preparation of low-viscosity base oils in the prior art.

[0012] To achieve the above and other related objectives, the present invention provides low-viscosity and medium-high viscosity polyalphaolefin base oils, their preparation methods, and applications.

[0013] The first aspect of the present invention provides a method for preparing polyα-olefin base oil, the method comprising: α-olefin dimer and haloalkane, and performing a hydrogen-alkylation reaction in an inert atmosphere mediated by alkyl metal halides.

[0014] Preferably, the alkyl metal halide is selected from any one or more of ethyl sesquialumina, diethyl aluminum chloride, diisobutyl aluminum chloride, methyl sesquialumina, or isobutyl sesquialumina.

[0015] Preferably, the α-olefin dimer has 12 to 24 carbon atoms.

[0016] More preferably, the α-olefin dimer has 14 to 22 carbon atoms.

[0017] More preferably, the α-olefin dimer has 16 to 20 carbon atoms; for example, it can be 16, 17, 18, 19 or 20.

[0018] Preferably, the number of carbon atoms in the haloalkane is 3 to 14.

[0019] More preferably, the number of carbon atoms in the haloalkane is 3 to 12.

[0020] More preferably, the number of carbon atoms in the haloalkane is 3 to 10; for example, it can be 3, 4, 5, 6, 7, 8, 9 or 10.

[0021] Preferably, the reaction route for the hydrogen-alkylation reaction to synthesize low-viscosity polyalphaolefin base oil is shown in the schematic diagram below.

[0022]

[0023] In the above route, there is only one double bond in Equation III, and the double bond can be located at the two places shown in Equation III.

[0024] Formula III is an α-olefin dimer;

[0025] For illustration, the compound of formula IV is a chloroalkanes among haloalkanes;

[0026] Compounds of Formula I and Formula II are hydrogen-alkylated products.

[0027] Where n takes the value of an integer from 2 to 8; R1 and R2 are independently H or straight-chain alkane groups with 1 to 12 carbon atoms, and R1 and R2 are not both H.

[0028] Preferably, the inert gas is any one or more selected from nitrogen, argon, or helium.

[0029] Preferably, the reaction temperature is -25 to 25°C.

[0030] More preferably, the reaction temperature is -15 to 25°C; for example, it can be -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C or 25°C.

[0031] Preferably, the reaction time is 10 to 15 hours.

[0032] More preferably, the reaction time is 10 to 14 hours; for example, it can be 10 hours, 11 hours, 12 hours, 13 hours, or 14 hours.

[0033] Preferably, the α-olefin dimer is a metallocene α-olefin dimer.

[0034] The metallocene α-olefin dimer described in this invention is an α-olefin dimer formed by the polymerization of α-olefins under metallocene catalysis.

[0035] Preferably, the metallocene α-olefin dimer has a viscosity of 1.5–8 mm at 40°C. 2 / s; for example, it can be 1.5mm. 2 / s, 2.0mm 2 / s, 2.5mm 2 / s, 3.0mm 2 / s, 3.5mm 2 / s, 4.0mm 2 / s, 4.5mm 2 / s, 5.0mm 2 / s, 5.5mm 2 / s, 6.0mm 2 / s, 6.5mm 2 / s, 7.0mm 2 / s, 7.5mm 2 / s or 8.0mm 2 / s.

[0036] Preferably, the viscosity of the metallocene α-olefin dimer at 100°C is 0.5–3 mm. 2 / s; for example, it can be 0.5mm. 2 / s, 1.0mm 2 / s, 1.5mm 2 / s, 2.0mm 2 / s, 2.5mm 2 / s, 3.0mm 2 / s, 3.5mm 2 / s or 4.0mm 2 / s.

[0037] Preferably, the pour point of the metallocene α-olefin dimer is <5°C.

[0038] More preferably, the pour point of the metallocene α-olefin dimer is < -20°C.

[0039] More preferably, the pour point of the metallocene α-olefin dimer is -50 to -20°C; for example, it can be -50°C, -45°C, -40°C, -35°C, -30°C, -25°C, or -20°C.

[0040] Preferably, the haloalkane is a straight-chain haloalkane.

[0041] Preferably, the haloalkane is any one or more selected from chloroalkanes, bromoalkanes, or fluoroalkanes.

[0042] More preferably, the haloalkane is a primary haloalkane and / or a secondary haloalkane.

[0043] Preferably, an organic solvent is also used in the reaction.

[0044] More preferably, the organic solvent is n-hexane.

[0045] Preferably, the mass ratio of the organic solvent to the alkyl metal halide is 1:(0.25-4).

[0046] More preferably, the mass ratio of the organic solvent to the alkyl metal halide is 1:(0.25-1); including but not limited to 1:0.25, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1.

[0047] Preferably, the molar ratio of the α-olefin dimer to the haloalkane is 1:(0.5-5).

[0048] More preferably, the molar ratio of the α-olefin dimer to the haloalkane is 1:(0.8-4).

[0049] More preferably, the molar ratio of the α-olefin dimer to the haloalkane is 1:(1 to 3); including but not limited to 1:1, 1:1.5, 1:2, 1:2.5 or 1:3.

[0050] Preferably, the molar ratio of the α-olefin dimer to the alkyl metal halide is 1:(0.5-3).

[0051] More preferably, the molar ratio of the α-olefin dimer to the alkyl metal halide is 1:(0.8-2.5).

[0052] More preferably, the molar ratio of the α-olefin dimer to the alkyl metal halide is 1:(1-2); including but not limited to 1:1, 1:1.1, 1:1.5 or 1:2.

[0053] Preferably, the method further includes adding a hydrogen donor, wherein the molar ratio of the α-olefin dimer to the hydrogen donor is 1:(0.5-5).

[0054] More preferably, the molar ratio of the α-olefin dimer to the hydrogen donor is 1:(0.8-3).

[0055] More preferably, the molar ratio of the α-olefin dimer to the hydrogen donor is 1:(1.5 to 2.5); including but not limited to 1:1.5, 1:1.7, 1:2, 1:2.1, 1:2.3 or 1:2.5.

[0056] More preferably, the hydrogen donor is any one or more selected from triethylsilane, trimethylsilane, or triphenylsilane.

[0057] Preferably, the method further includes washing the product.

[0058] More preferably, the washing process uses an alkaline aqueous solution with a pH of 7.5 to 9.

[0059] More preferably, the washing process uses an alkaline aqueous solution with a pH of 8 to 9.

[0060] More preferably, the alkali is selected from any one or more of sodium bicarbonate, sodium carbonate, and sodium hydroxide.

[0061] The purpose of washing the product with an alkaline aqueous solution in this invention is to remove alkyl metal halides from the reaction product.

[0062] Preferably, the method further includes distilling the product to remove the reaction solvent, wherein the distillation conditions are 70–90°C; for example, 70°C, 75°C, 80°C, 85°C or 90°C.

[0063] Preferably, the method further includes distillation separation of the product.

[0064] More preferably, the distillation separation includes distilling off unreacted haloalkanes and hydrogen donors at a temperature of 140–160°C and a vacuum of 1–1.5 mbar; for example, the distillation temperature can be 140°C, 145°C, 150°C, 155°C, or 160°C, and the distillation vacuum can be 1.0 mbar, 1.1 mbar, 1.2 mbar, 1.3 mbar, 1.4 mbar, or 1.5 mbar.

[0065] More preferably, the distillation separation includes distilling off unreacted α-olefin dimers at 180–190°C and a vacuum of 1–1.5 mbar; for example, the distillation temperature can be 180°C, 185°C, or 190°C, and the distillation vacuum can be 1.0 mbar, 1.1 mbar, 1.2 mbar, 1.3 mbar, 1.4 mbar, or 1.5 mbar.

[0066] More preferably, the distillation separation includes distilling off the α-olefin dimer and the hydrogen-alkylated product of the haloalkane at a vacuum of 1–1.5 mbar at 200–260°C; for example, the distillation temperature can be 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C, 255°C, or 260°C, and the distillation vacuum can be 1.0 mbar, 1.1 mbar, 1.2 mbar, 1.3 mbar, 1.4 mbar, or 1.5 mbar.

[0067] A second aspect of the present invention provides a low-viscosity polyalphaolefin base oil prepared by the above-described preparation method, wherein the structure of the low-viscosity polyalphaolefin base oil comprises compounds as shown in Formula I or Formula II:

[0068]

[0069] Where n takes the value of an integer from 2 to 8, R1 and R2 are independently H or straight-chain alkane groups with 1 to 12 carbon atoms, and R1 and R2 are not both H.

[0070] Preferably, the value of n is an integer from 2 to 7; for example, it can be any value among 2, 3, 4, 5, 6, and 7.

[0071] Preferably, R1 and R2 are each independently H or a straight-chain alkane group with 1 to 8 carbon atoms; for example, they can be -CH2CH3, -(CH2)2CH3, -(CH2)3CH3, -(CH2)4CH3, -(CH2)5CH3, -(CH2)6CH3 or -(CH2)7CH3.

[0072] More preferably, R1 and R2 are not both H.

[0073] In some preferred embodiments of the present invention, R1 is a straight-chain alkane group having 1 to 12 carbon atoms; R2 is H or methyl.

[0074] Preferably, the low-viscosity polyalphaolefin base oil has 16 to 36 carbon atoms.

[0075] More preferably, the low-viscosity polyalphaolefin base oil has 18 to 32 carbon atoms.

[0076] More preferably, the low-viscosity polyalphaolefin base oil has 20 to 30 carbon atoms; for example, it can be 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30.

[0077] Preferably, the low-viscosity polyalphaolefin base oil has a kinematic viscosity of 1.5–10 mm at 100°C. 2 / s.

[0078] More preferably, the low-viscosity polyalphaolefin base oil has a kinematic viscosity of 1.6–3.6 mm at 100°C. 2 / s; for example, it could be 1.6mm. 2 / s, 1.69mm 2 / s, 1.8mm 2 / s, 2.0mm 2 / s, 2.3mm 2 / s, 2.35mm 2 / s, 2.5mm 2 / s, 3.0mm 2 / s, 3.5mm 2 / s, 4.0mm 2 / s, 4.5mm 2 / s, 5.0mm 2 / s, 5.5mm 2 / s, 6.0mm 2 / s, 6.5mm 2 / s, 7.0mm 2 / s, 7.5mm 2 / s, 8.0mm 2 / s, 8.5mm 2 / s, 9.0mm 2 / s, 9.5mm 2 / s or 10mm 2 / s.

[0079] Preferably, the low-viscosity polyalphaolefin base oil has a pour point of < -60°C.

[0080] More preferably, the pour point of the low-viscosity polyalphaolefin base oil is -80℃ to -62℃; for example, it can be -80℃, -78℃, -76℃, -75℃, -72℃, -70℃, -68℃, -65℃ or -62℃.

[0081] Preferably, the low-viscosity polyalphaolefin base oil has an open flash point >150°C.

[0082] More preferably, the open flash point of the low viscosity polyalphaolefin base oil is 160-200°C; for example, it can be 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C or 200°C.

[0083] The low-viscosity polyα-olefin base oil of the present invention is obtained by distillation of the reaction product obtained by hydrogen-alkylation reaction of α-olefin dimer and haloalkanes at 230-260°C and a vacuum of 1-1.5 mbar.

[0084] A third aspect of the present invention provides a medium-to-high viscosity polyα-olefin base oil prepared by the above-described preparation method.

[0085] The medium-high viscosity polyalphaolefin base oil in this invention is an oligomer generated in the hydrogen-alkylation reaction. After the alpha-olefin dimer and haloalkanes undergo hydrogen-alkylation reaction, the crude product obtained is distilled to remove the solvent, unreacted alpha-olefin dimer and hydrogen-alkylation product, and the remaining product is the medium-high viscosity polyalphaolefin base oil.

[0086] Preferably, the medium-high viscosity polyalphaolefin base oil has a weight-average molecular weight of 1000 to 8000.

[0087] More preferably, the weight-average molecular weight of the medium-high viscosity polyalphaolefin base oil is 1000 to 5000; for example, it can be 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500 or 5000.

[0088] Preferably, the number-average molecular weight of the medium-high viscosity polyalphaolefin base oil is 800 to 5000.

[0089] More preferably, the number average molecular weight of the medium-high viscosity polyalphaolefin base oil is 800 to 3500; for example, it can be 800, 1000, 1500, 2000, 2500, 3000 or 3500.

[0090] Preferably, the medium-high viscosity polyalphaolefin base oil has a kinematic viscosity > 10 mm at 100°C. 2 / s

[0091] Preferably, the medium-high viscosity polyalphaolefin base oil has a kinematic viscosity of 10.5–300 mmHg at 100°C. 2 / s.

[0092] More preferably, the medium-high viscosity polyalphaolefin base oil has a kinematic viscosity of 10.5–100 mm at 100°C. 2 / s.

[0093] More preferably, the medium-high viscosity polyalphaolefin base oil has a kinematic viscosity of 10.5–25 mm at 100°C. 2 / s; for example, it can be 10.5mm. 2 / s, 11mm 2 / s, 12mm 2 / s, 13mm 2 / s, 14mm 2 / s, 15mm 2 / s, 16mm 2 / s, 17mm 2 / s, 18mm 2 / s, 19mm 2 / s, 20mm 2 / s, 21mm 2 / s, 22mm 2 / s, 23mm 2 / s, 24mm 2 / s or 25mm 2 / s.

[0094] Preferably, the viscosity index of the medium-high viscosity polyalphaolefin base oil is >150.

[0095] More preferably, the viscosity index of the medium-high viscosity polyalphaolefin base oil is 151 to 160; for example, it can be 151, 152, 153, 154, 155, 156, 157, 158, 159 or 160.

[0096] Preferably, the pour point of the medium-high viscosity polyalphaolefin base oil is < -40°C.

[0097] More preferably, the pour point of the medium-high viscosity polyalphaolefin base oil is -50℃ to -41℃; for example, it can be -50℃, -49℃, -48℃, -47℃, -46℃, -45℃, -44℃, -43℃, -42℃ or -41℃.

[0098] The fourth aspect of the present invention provides the application of the above-mentioned low-viscosity polyalphaolefin base oil or medium-high viscosity polyalphaolefin base oil in the preparation of lubricating oil or grease products.

[0099] As described above, the low-viscosity and medium-high viscosity polyα-olefin base oils of the present invention, their preparation methods, and their uses have the following beneficial effects:

[0100] 1. The preparation of the low-viscosity and medium-high viscosity polyalphaolefin base oils of this invention does not require the use of toxic catalysts, reduces damage to equipment, and does not cause environmental pollution.

[0101] 2. The poly-α-olefin base oil prepared by the preparation method of this invention is a fully saturated alkane, which does not require a later expensive and dangerous hydrogenation process.

[0102] 3. When preparing polyalphaolefin base oil using the preparation method of the present invention, the total hydrocarbon yield can reach more than 90%, the content of low viscosity polyalphaolefin base oil can reach more than 50%, and the oligomers generated in the preparation process can be used as medium and high viscosity base oils, reducing product waste.

[0103] 4. The preparation method of this invention can precisely control the basic molecular structure of the synthesis through the reaction substrate, thereby preparing PAO with different viscosities, providing a new technical route for the molecular engineering design of synthetic lubricating oils.

[0104] 5. The low-viscosity polyα-olefin base oil prepared by this invention has a well-defined molecular structure, excellent low-temperature performance and lubrication performance, and can be used as a base oil to prepare lubricating oil or grease products. Attached Figure Description

[0105] Figure 1 The results are shown as gas chromatographic detection results of the products of Examples 2 and 3 of this invention; wherein Figure 1 a represents the product detection results of Example 2. Figure 1 b represents the product detection results of Example 3.

[0106] Figure 2 The image shows gel chromatograms of the molecular weight distribution of the oligomers produced in Examples 3 and 5-6 of this invention.

[0107] Figure 3 The product shown is the C20 and 1-chloropropane product in Example 10 of this invention. 13 C10 NMR spectrum.

[0108] Figure 4 The product shown is the C20 and 1-chlorodecane product in Example 5 of this invention. 13 C10 NMR spectrum. Detailed Implementation

[0109] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0110] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0111] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the presence of other method steps before or after the combined steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0112] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention; in the specification and claims of the present invention, unless otherwise expressly stated in the text, the singular forms "a", "an" and "this" include the plural forms.

[0113] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0114] The following compounds and intermediates were characterized by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR). The starting materials and reagents used in the preparation of these compounds were available from suppliers or prepared by methods known to those skilled in the art. The following general synthetic routes are merely illustrative of methods by which the compounds of the present invention can be synthesized, and various modifications to these synthetic routes are possible and inspired by those skilled in the art who have referred to this disclosure.

[0115] This invention provides a novel synthetic route for low-viscosity polyalphaolefin (PAO) base oils. Mediated by ethyl sesquichloride (Et3Al2Cl3), the inactive C=C double bond of olefins can undergo a hydroalkylation reaction with chloroalkanes. The alkyl carbocation generated from dechlorination attacks the C=C double bond of the inner olefin, forming a secondary adduct carbocation. Subsequently, 1,2-hydrogen migration occurs, generating a more stable tertiary carbocation. After ethyl sesquichloride transfers hydride anions to the tertiary carbocation and eliminates ethylene, a saturated hydroalkylated product is finally obtained. This invention utilizes selective hydrogen-alkylation to couple chloroalkanes with the olefin double bond in metallocene-based high-carbon alpha-olefin dimers, promoting branching structural modification to prepare ultra-low-viscosity PAO (PAO2 and PAO3.5) base oils with well-defined molecular structures. A schematic diagram of the specific reaction pathway is shown below. Figure 1 As shown.

[0116] The applicant discovered that under specific reaction conditions, α-olefin dimers not only failed to undergo the expected dimerization or trimerization reactions, but also exhibited a significant tendency towards high polymerization. This polymer has a PAO-like structure and can be used as a medium-to-high viscosity base oil, showing potential application value in lubricating oils. Furthermore, the halogenated hydrocarbons exhibit bifunctional reaction characteristics in this catalytic system. The generated carbocations can not only participate in conventional hydrogen-alkylation reactions as alkylating agents, but also activate the inner olefins through β-hydrogen transfer reactions, enabling them to undergo oligomerization. Based on this bifunctional reaction mechanism, this invention successfully synthesized polyalphaolefin (PAO) base oils of different viscosity grades using halogenated hydrocarbons as alkylating agents and metallocene-based high-carbon α-olefin dimers as raw materials, providing a new route for the synthesis of PAOs with well-defined structures.

[0117] Example 1

[0118] This embodiment uses metallocene catalysis to prepare α-olefin dimers. The specific preparation method is as follows:

[0119] Synthesis of metallocene dimer (C20) catalyzed by metallocene: First, 5 mL of toluene and 0.02 g of bis(tetrahydroindenyl)zirconia dichloride were added to a 15 mL Schlenk flask. Then, 0.06 g of N,N-dimethylaniline tetra(pentafluorophenyl)borate and 5 mL of triisobutylaluminum toluene solution were added successively, followed by vigorous shaking for 1 min to prepare the metallocene catalyst solution. Next, 500 g of 1-decene was added to a dried 1000 mL four-necked flask. After purging with high-purity nitrogen three times, heating was initiated. When the 1-decene was heated to 110 °C, the prepared metallocene catalyst solution was added in three portions using a glass syringe. After all the solution was added, stirring was continued for 1 h, maintaining the reaction temperature between 110-115 °C. After the reaction was complete, 1% acidic clay was added, and stirring was continued for another 1 h. The mixture was then filtered to obtain a clear crude product. 300g of 1-decene dimer was separated by distillation using a thin-film evaporator at 180℃ and a vacuum of 1.2mbar.

[0120] Dimers of 1-octene and 1-dodecene (C16 and C24) were prepared using the same operating procedure described above. The products were separated by vacuum distillation, with the 1-octene dimer collected at 150 °C and 1.2 mbar, and the 1-dodecene dimer distilled off at 210 °C and 1.2 mbar.

[0121] The three dimer products obtained by the above method can all be used as precursors for the hydrogen-alkylation reaction.

[0122] The properties of the α-olefin dimers prepared above were tested, and the results are shown in Table 1. The specific test methods included:

[0123] Viscosity / mm 2 / s Test method / standard: GB / T 265;

[0124] Pour point / °C test method / standard: GB / T 3535;

[0125] Open flash point / °C test method / standard: GB / T 3536-2008.

[0126] Table 1. Viscosity-temperature properties and content of the prepared dimers

[0127]

[0128] In Examples 2-9 and Comparative Examples 1-2 below, 1-decene dimer (C20) and 1-chlorodecane were used as reactants.

[0129] Example 2

[0130] 80 g of C20 and 70 g of 1-chlorodecane were added to a dry 500 mL double-walled glass reaction flask equipped with a constant-pressure funnel. After purging with high-purity nitrogen three times, 300 g of a hexane solution containing ethyl sesquichloride (with a mass concentration of 27.2% ethyl sesquichloride) was added to the constant-pressure funnel and added dropwise to the reaction flask over 2 hours. The reaction temperature was controlled at 15 °C using a circulating bath, and the reaction was carried out for 12 hours. After the reaction, the product was washed with a 10% sodium bicarbonate solution. The crude product was distilled off to remove hexane at atmospheric pressure and 80 °C, and then separated by micro-distillation. First, unreacted 1-chlorodecane and triethylsilane were distilled off under a vacuum of 1.2 mbar at 150 °C. Unreacted C20 was distilled off at 190 °C and 1.2 mbar, and the hydrogen-alkylated product (C30-1) of C20 and 1-chlorodecane was distilled off at 250 °C and 1.2 mbar.

[0131] Example 3

[0132] The difference from Example 2 is that 70.8 g of triethylsilane was added to a solution of 1-chlorodecane and C20. Other experimental methods and operating conditions were the same as in Example 2. Table 2 shows the comparison of yields and product distribution between Example 3 and Example 2. Gas chromatographic detection results of the products from Examples 2 and 3 are as follows: Figure 1 As shown, where Figure 1 a represents the product detection results of Example 2. Figure 1 b represents the product detection results of Example 3, where the calculation formulas for total hydrocarbon yield, olefin conversion rate, and chloroalkane conversion rate are as follows:

[0133]

[0134] Where m0 is the molecular weight of the chloroalkane, m a m represents the feed mass of olefins. b m represents the total weight of hydrocarbons obtained after vacuum distillation at 150℃. c m represents the mass of chloroalkanes fed. d This represents the mass of the unreacted olefin.

[0135] Table 2. Effect of triethylsilane on the hydroalkylation of C20 and 1-chlorosilane.

[0136]

[0137] according to Figure 1As shown in Table 2, when triethylsilane is not added during the reaction, side reactions significantly increase. In addition to the hydroalkylation product C30, 21.4% of C20 dimers (C40) are produced, and even 7.6% of the C20 dimer is formed as a hydroalkylation product of 1-chlorodecane (C50), along with a small amount of oligomers. However, with the addition of triethylsilane, the main products are C30 and oligomers (the oligomers, due to their high boiling point, cannot be fully volatilized under conventional gas chromatography analysis conditions, resulting in their inability to be effectively identified within the gas chromatography detection range), and a very small amount of C40 (1.3%). This indicates that the addition of triethylsilane can effectively inhibit the dimerization reaction of olefins.

[0138] Example 4

[0139] 80 g of C2O and 50.5 g of 1-chlorodecane were added to a dry 500 mL double-walled glass reaction flask equipped with a constant-pressure funnel, followed by 70.8 g of triethylsilane. After purging with high-purity nitrogen three times, 300 g of a hexane solution containing ethyl sesquichloride (with a mass concentration of 27.2% ethyl sesquichloride) was added to the constant-pressure funnel and added dropwise to the reaction flask over 2 hours. The reaction temperature was maintained at 15 °C using a circulating bath, and the reaction was carried out for 12 hours. After the reaction, the product was washed with a 10% sodium bicarbonate solution. The crude product was distilled off at 80 °C under normal pressure to remove hexane, and then separated by micro-distillation.

[0140] Example 5

[0141] The difference from Example 4 is that 105g of 1-chlorodecane was added, while the other experimental methods and operating conditions were the same as in Example 4.

[0142] Example 6

[0143] The difference from Example 4 is that 140g of 1-chlorodecane was added, while the other experimental methods and operating conditions were the same as in Example 4.

[0144] Comparative Example 1

[0145] The difference from Example 4 is that 210g of 1-chlorodecane was added, while the other experimental methods and operating conditions were the same as in Example 4.

[0146] Comparative Example 2

[0147] The difference from Example 6 is that, while keeping the amount of ethyl sesquialuminate added unchanged, the amounts of C20, 1-chlorodecane, and triethylsilane are all reduced to half.

[0148] The effects of different amounts of reactants added in Examples 4-6 and Comparative Examples 1-2 on the reaction are shown in Table 3.

[0149] Table 3. Effect of different reactant ratios on the hydrogen-alkylation reaction.

[0150]

[0151] As shown in Table 1, in Example 4, when the molar ratio of C20 to 1-chlorodecane was 1:1, no oligomers were produced in the product, C30 was prepared with high selectivity, and only a very small amount of dimer C40 was produced. Based on the results of Examples 4-6, as the proportion of 1-chlorodecane gradually increased, the yield of total hydrocarbons and the conversion rate of 1-chlorodecane showed the same trend, first increasing and then decreasing, while the conversion rate of 1-decene dimers changed by approximately 75%. However, when the ratio of C20 to 1-chlorodecane exceeded 1:1, the proportion of C30 in the product decreased. In Examples 5 and 6, although the changes in the C30 and C40 components in the product were not significant, the viscosity of the oligomers increased rapidly with the increase of the proportion of 1-chlorodecane. In Comparative Example 1, when the amount of 1-chlorodecane added was too large, the yield of total hydrocarbons dropped to about 70%, while the conversion rate of 1-chlorodecane decreased to about 50%. This shows that excessive 1-chlorodecane cannot react completely, leading to a significant decrease in conversion rate. In Comparative Example 2, when the amount of ethyl sesquichloride added was large, the proportion of oligomers in the product increased, and the viscosity of the oligomers was too high, making them unusable.

[0152] The oligomers produced in Examples 3 and 5-6 were analyzed by gel permeation chromatography, and the results are as follows: Figure 2 As shown, the results indicate that in the presence of excess 1-chlorodecane, the molecular weight distribution of all oligomers exhibits a clear bimodal distribution. Due to the presence of 1-decene and α-olefin dimers, two olefins with significantly different structures, their steric hindrances are also greatly different, leading to different insertion rates during polymerization and consequently, different molecular weights in the resulting polymers. Furthermore, during polymerization, some polymers undergo hydride transfer to the polymer in the presence of the hydrogen donor triethylsilane, saturating it and ending chain growth, thus losing reactivity. Others undergo β-hydrogen transfer to form double bonds and end chain growth. Excess decane carbocations are reactivated through β-hydrogen transfer, becoming active centers for chain growth and generating polymers with larger molecular weights, resulting in the bimodal pattern and a wider molecular weight distribution.

[0153] Example 7

[0154] The difference from Example 5 is that the reaction temperature is -15°C, while the other experimental methods and operating conditions are the same as in Example 5.

[0155] Example 8

[0156] The difference from Example 5 is that the reaction temperature is 0°C, while the other experimental methods and operating conditions are the same as in Example 5.

[0157] Example 9

[0158] The difference from Example 5 is that the reaction temperature is 25°C, while the other experimental methods and operating conditions are the same as in Example 5.

[0159] The effects of different reaction temperatures on the reaction data in Examples 5 and 7-9 are shown in Table 4.

[0160] Table 4 Effect of reaction temperature on hydrogen-alkylation reaction

[0161]

[0162] Table 4 shows that 1-decene dimer and 1-chlorodecane exhibit high reactivity. Even at relatively low reaction temperatures, the conversion rate of 1-chlorodecane can still reach 83%. With increasing reaction temperature, the total hydrocarbon yield and the conversion rates of C20 and 1-chlorodecane all increase to varying degrees. A higher conversion rate can be achieved at 15℃. Looking at the changes in the total hydrocarbon product composition, the selectivity for C30 decreases with increasing reaction temperature, while the yield of oligomers increases significantly, and the content of C40 also increases significantly. Therefore, the desired viscosity grade of oligomer can be obtained by adjusting the reaction temperature.

[0163] Examples 10-13 and Comparative Examples 3-4 below used 1-decene dimer (C20) and different chloroalkanes as reactants.

[0164] Example 10

[0165] 293g of a hexane solution containing ethyl sesquichloride (with a mass concentration of 27.2% ethyl sesquichloride) was added to a dry 1000mL double-walled glass reaction flask. 57g of triethylsilane and 64g of C20 were weighed and added to the flask. The reaction temperature was maintained at -15℃ by turning on a cold bath. 29g of 1-chloropropane was added to a constant-pressure funnel and slowly added dropwise to the reaction system. After the addition was complete, the reaction was allowed to proceed for 14 hours. After the reaction was complete, the mixture was washed with a 10% sodium bicarbonate solution. The crude product was distilled off at 80℃ under normal pressure to remove the hexane, and then separated by micro-distillation using the same distillation method as in Example 2. The distillation conditions for the hydrogen-alkylated product (C23) of C20 and 1-chloropropane were 200℃ and 1.2mbar.

[0166] Example 11

[0167] The difference from Example 10 is that 34g of 1-chloro-n-butane was added, while other experimental methods and operating conditions were the same as in Example 10; the specific distillation separation was the same as in Example 2, wherein the distillation conditions for the hydrogen-alkylation product (C24) of C20 and 1-chloro-n-butane were 210°C and 1.2mbar.

[0168] Example 12

[0169] The difference from Example 10 is that 44.5g of 1-chlorohexane was added, and the other experimental methods and operating conditions were the same as in Example 10; the specific distillation separation was the same as in Example 2, wherein the distillation conditions for the hydrogen-alkylation product (C26) of C20 and 1-chlorohexane were 220°C and 1.2mbar.

[0170] Example 13

[0171] The difference from Example 10 is that 55g of 1-chloro-n-octane was added, while other experimental methods and operating conditions were the same as in Example 10; the specific distillation separation was the same as in Example 2, wherein the distillation conditions for the hydrogen-alkylation product (C28) of C20 and 1-chloro-n-octane were 235°C and 1.2mbar.

[0172] Comparative Example 3

[0173] The difference from Example 10 is that 44.5g of 2-methyl-1-chlorononane was added, and the other experimental methods and operating conditions were the same as in Example 10; the specific distillation separation was the same as in Example 2, wherein the distillation conditions for C20 and the hydrogen-alkylated product (C30-2) of 2-methyl-1-chlorononane were 250°C and 1.2mbar.

[0174] Comparative Example 4

[0175] The difference from Example 10 is that 55g of 3,7-dimethyl-1-chlorooctane was added, and the other experimental methods and operating conditions were the same as in Example 10; the specific distillation separation was the same as in Example 2, wherein the distillation conditions for the hydrogen-alkylation products (C30-3) of C20 and 2-methyl-1-chlorononane were 250°C and 1.2mbar.

[0176] The results of the effects of different chloroalkanes on the reaction in Examples 10-13 and Comparative Examples 3-4 are shown in Table 5.

[0177]

[0178] As shown in Table 5, the carbon chain length significantly affects the reactivity. The olefin conversion rate gradually increases with shortening of the carbon chain, with 1-chloropropane exhibiting the highest reactivity. In Examples 10-13, all straight-chain chloroalkanes showed high conversion rates (≥95%), with the total hydrocarbon yield remaining stable at approximately 97%. Under excess chloroalkane conditions, short-chain reactants rapidly completed olefin addition due to low steric hindrance, with a C23 product yield approaching 90% and extremely low oligomer content. As the carbon chain length increased, the oligomer content significantly increased. Furthermore, in Comparative Examples 3-4, the use of branched chloroalkanes increased steric hindrance, leading to a significant decrease in total hydrocarbon yield, olefin conversion rate, and chloroalkane conversion rate. This indicates that straight-chain chloroalkanes performed better than branched chloroalkanes.

[0179] The reaction products of Examples 10 and 5 were characterized by carbon NMR spectroscopy, and the results are as follows: Figure 3 and Figure 4 As shown, the results indicate that when 1-chloropropane is used, a variety of C23 products can be generated due to its smaller steric hindrance; when 1-chlorodecane is used, only terminal olefin addition products are generated due to its larger steric hindrance.

[0180] The following Examples 14 and Comparative Examples 5-6 used different α-olefin dimers and different chloroalkanes as reactants.

[0181] Example 14

[0182] 268g of a hexane solution containing ethyl sesquichloride (with a mass concentration of 50% ethyl sesquichloride) was added to a dry 1000mL double-walled glass reaction flask. 78g of triethylsilane and 101g of C16 were weighed and added to the flask. The reaction temperature was maintained at -15℃ by turning on a cold bath. 41.8g of 1-chlorobutane was added to a constant-pressure funnel and slowly added dropwise to the reaction system. After the addition was complete, the reaction was allowed to proceed for 14 hours. After the reaction was complete, the mixture was washed with a 10% sodium bicarbonate solution. The crude product was distilled off at 80℃ under normal pressure to remove the hexane, and then separated by micro-distillation using the same method as in Example 2, yielding the hydrogen-alkylated product (C20') of C16 and 1-chlorobutane.

[0183] Comparative Example 5

[0184] 392g of a hexane solution containing ethyl sesquichloride (with a mass concentration of 50% ethyl sesquichloride) was added to a dry 1000mL double-walled glass reaction flask. 114g of triethylsilane and 148g of C16 were weighed and added to the flask. The reaction temperature was maintained at -15℃ by turning on a cold bath. 153g of 1-chloro-n-tetradecane was added to a constant-pressure funnel and slowly added dropwise to the reaction system. After the addition was complete, the reaction was allowed to proceed overnight. After the reaction was complete, the mixture was washed with a 10% sodium bicarbonate solution. The crude product was distilled off at 80℃ under normal pressure to remove hexane, and then separated by micro-distillation using the same method as in Example 2, yielding C16 and the hydrogen-alkylated product (C30-4) of 1-chloro-n-tetradecane.

[0185] Comparative Example 6

[0186] 395g of a hexane solution containing ethyl sesquichloride (with a mass concentration of 50% ethyl sesquichloride) was added to a dry 1000mL double-walled glass reaction flask. 114g of triethylsilane and 223g of C24 were weighed and added to the flask. The reaction temperature was maintained at -15℃ by turning on a cold bath. 80g of 1-chlorohexane was added dropwise to the reaction system through a constant pressure funnel. After the addition was complete, the reaction was allowed to proceed overnight. After the reaction was complete, the mixture was washed with a 10% sodium bicarbonate solution. The crude product was distilled off at 80℃ under normal pressure to remove the hexane, and then separated by micro-distillation using the same method as in Example 2, yielding C24 and the hydrogen-alkylated products (C30-5) of 1-chlorohexane.

[0187] Data on the reactions of different α-olefin dimers and chloroalkanes in Example 14 and Comparative Examples 5-6 are shown in Table 6.

[0188] Table 6. Effects of different α-olefin dimers and chloroalkanes on the hydrogen-alkylation reaction.

[0189]

[0190] As shown in Table 6, when the carbon chain of the α-olefin dimer or chloroalkane is too long, the conversion rate of the olefin is significantly reduced, and the C20 or C30 product is significantly decreased. The pour points of the C20 product in Example 14 and the C30 products in Comparative Examples 5-6 were tested and compared with the pour points of the α-olefin dimers in Table 1. The results show that the pour point of the C20 product synthesized from C16 and 1-chlorobutane via hydrogen-alkylation in Example 14 can reach -78℃, which is significantly lower than that of C16. However, the pour point of the C30 synthesized from C16 and 1-chlorotetradecane did not improve but rather deteriorated significantly (from -43℃ to -30℃). Although the pour point of the C30 product synthesized from C24 and 1-chlorohexane was significantly improved, it was still much higher than -78℃. The common feature of both is that the C30 products have long alkyl backbones, which seriously affect the low-temperature performance of the products.

[0191] The viscosity-temperature properties and low-temperature flowability of the C20 products prepared in Examples 10 and 14, the C30 product prepared in Example 4, and the oligomer prepared in Example 5 were measured. The results are shown in Table 7. The specific test methods included:

[0192] The test methods for viscosity, pour point, and open flash point are the same as above.

[0193] Viscosity index calculation method / standard: GB / T 1995-1998 Method B.

[0194] Table 7. Viscosity-temperature properties of synthesized PAO2, PAO3.5, and PAO20

[0195]

[0196] The results in Table 7 show that the C20 product prepared in Example 14 has a low pour point and suitable viscosity, making it suitable for commercial use as PAO2. The C20 product prepared in Example 10 has a low pour point, with an open flash point of 175°C. A high flash point is beneficial for improving the safety of lubricating oil, especially in applications such as data centers and energy storage facilities where high coolant requirements are necessary. Its viscosity at 100°C is 2.35 mm. 2 The product can be blended with other low-viscosity base oils as PAO2, or with other base oils of different viscosities as PAO2.5 or PAO3; the C30 product prepared in Example 4 can be used as PAO3.5. Furthermore, the oligomer prepared in this application has a higher viscosity index than commercially available PAO20, indicating that the viscosity of the oligomer in this application changes less with temperature, meaning its viscosity is relatively stable over a wide temperature range. It also has comparable pour point and flash point to commercially available PAO20, demonstrating good application prospects and avoiding the waste of oligomer byproducts in existing technologies.

[0197] In summary, this invention provides a novel technical route for synthesizing low-viscosity and medium-to-high-viscosity PAO. This route uses α-olefin dimer byproducts generated during the metallocene-catalyzed synthesis of polyα-olefins from α-olefins as raw materials, reducing energy waste. Furthermore, the reaction process does not require toxic catalysts, resulting in no environmental pollution, and eliminates the need for subsequent expensive and dangerous hydrogenation processes. The prepared low-viscosity PAO possesses a well-defined molecular structure. In addition to the different viscosities of PAO listed in this invention, in practical applications, PAOs with varying viscosities can be obtained by adjusting the carbon chain length of the reactants, the feed amount, and the reaction temperature, thus meeting industrial demands. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0198] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a polyalphaolefin base oil, characterized in that, The preparation method includes: α-olefin dimer and haloalkane, and hydrogen-alkylation reaction in an inert atmosphere mediated by alkyl metal halides.

2. The preparation method according to claim 1, characterized in that, The alkyl metal halide is selected from any one or more of ethyl sesquialumina, diethyl aluminum chloride, diisobutyl aluminum chloride, methyl sesquialumina, or isobutyl sesquialumina; and / or, the α-olefin dimer has 12 to 24 carbon atoms; and / or, the haloalkane has 3 to 14 carbon atoms; and / or, the inert gas is selected from any one or more of nitrogen, argon, or helium; and / or, the reaction temperature of the hydrogen-alkylation reaction is -25 to 25°C; and / or, the reaction time of the hydrogen-alkylation reaction is 10 to 15 h.

3. The preparation method according to claim 1, characterized in that, The α-olefin dimer is a metallocene α-olefin dimer; and / or, the haloalkane is a straight-chain haloalkane; and / or, the haloalkane is any one or more selected from chloroalkanes, bromoalkanes, or fluoroalkanes; and / or, an organic solvent is also used in the reaction.

4. The preparation method according to claim 3, characterized in that, The organic solvent is n-hexane; and / or, the mass ratio of the organic solvent to the alkyl metal halide is 1:(0.25-4).

5. The preparation method according to claim 1, characterized in that, The molar ratio of the α-olefin dimer to the haloalkane is 1:(0.5-5); and / or, the molar ratio of the α-olefin dimer to the alkyl metal halide is 1:(0.5-3).

6. The preparation method according to claim 1, characterized in that, The method further includes adding a hydrogen donor, wherein the molar ratio of the α-olefin dimer to the hydrogen donor is 1:(0.5-5); and / or, the method further includes washing the product with an alkaline aqueous solution of pH 7.5-9; and / or, the method further includes distilling the product.

7. The preparation method according to claim 6, characterized in that, The hydrogen donor is selected from any one or more of triethylsilane, trimethylsilane, or triphenylsilane; and / or, the base is selected from any one or more of sodium bicarbonate, sodium carbonate, and sodium hydroxide; and / or, the distillation separation includes distilling off unreacted haloalkanes and hydrogen donors at a vacuum of 1 to 1.5 mbar at 140–160 °C; and / or, the distillation separation includes distilling off unreacted α-olefin dimers at a vacuum of 1 to 1.5 mbar at 180–190 °C; and / or, the distillation separation includes distilling off hydrogen-alkylated products at a vacuum of 1 to 1.5 mbar at 200–260 °C.

8. A low-viscosity polyα-olefin base oil prepared by any one of claims 1 to 7, characterized in that, The low-viscosity polyalpha-olefin base oil comprises compounds with structures shown in Formula I and / or Formula II: Where n takes the value of an integer from 2 to 8; R1 and R2 are independently H or straight-chain alkane groups with 1 to 12 carbon atoms, and R1 and R2 are not both H.

9. The low-viscosity polyalphaolefin base oil according to claim 8, characterized in that, The low-viscosity polyalphaolefin base oil has the following properties: kinematic viscosity of 1.5–10 mm at 100°C. 2 / s; Pour point < -60℃; Open flash point > 150℃.

10. A medium-to-high viscosity polyα-olefin base oil prepared by any one of claims 1 to 7, characterized in that, The medium-high viscosity polyalphaolefin base oil has a weight-average molecular weight of 1000–8000; and / or, the medium-high viscosity polyalphaolefin base oil has a number-average molecular weight of 800–5000; and / or, the medium-high viscosity polyalphaolefin base oil has the following properties: kinematic viscosity at 100°C > 10 mm. 2 / s; viscosity index >150; pour point <-40℃.

11. The use of a low-viscosity polyalphaolefin base oil as described in any one of claims 8 to 9 or a medium-to-high viscosity polyalphaolefin base oil as described in claim 10 in the preparation of lubricating oils or greases.

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