CN106883899B - Preparation method of poly alpha-olefin synthetic oil with high viscosity index - Google Patents

Abstract

The invention relates to a preparation method of poly alpha-olefin synthetic oil with high viscosity index, which comprises the following steps: adding an oligomerization catalyst into the raw materials, and reacting for 30-120 min at the temperature of 20-50 ℃; separating the catalyst, the reaction product and the unreacted alpha-olefin monomer, distilling and hydrogenating the reaction product to obtain the poly alpha-olefin synthetic oil with the kinematic viscosity of more than 40cSt and the viscosity index of more than 150 at 100 ℃. The method uses cheap branched chain alpha-olefin as a synthetic raw material to replace expensive 1-decene for polymerization to prepare the PAO with high viscosity index. The branched chain alpha-olefin is used as a synthetic raw material, not only can a byproduct be utilized, the utilization rate is improved, but also the high-viscosity-index PAO is prepared by adopting the self-produced decene to replace the expensive 1-decene for polymerization, the cost is reduced, and the economic benefit is increased.

Description

A kind of preparation method of polyalpha-olefin synthetic oil with high viscosity index

technical field

The invention relates to a preparation method of polyalpha-olefin synthetic oil, in particular to a preparation method of high-viscosity polyalpha-olefin synthetic oil suitable for preparing lubricating oil base oil.

Background technique

Polyalphaolefin (PAO) synthetic oil is currently the best synthetic lubricating oil base oil, with high viscosity index, low volatility, low fluidity, good shear performance and excellent high temperature oxidation resistance; and Compared with traditional mineral lubricating oil base oils (I, II, III base oils), PAO has the characteristics of small evaporation loss, good stability, wide temperature range, good compatibility with common materials and non-toxicity. It is not only used in automobiles It is widely used in civilian industries such as aviation, aerospace, and military industries, and it is also the main source of high-grade lubricating oil base oils used in aviation, aerospace, military and other industries.

PAO is generally a class of oligomers with branched chain saturation formed by catalytic oligomerization of C ₆ -C ₂₀ α-olefins, among which 1-decene is the preferred material, and commonly used oligomerization catalyst systems include BF ₃ system, Cr system, Al compound system and Ziegler-Natta etc. Catalytic polymerization of alpha-olefins is a known technique for preparing PAO synthetic lubricating oils. The method for producing PAO is disclosed in many patents, such as US Patent Nos. 3149178; 3382291; 3742082; 3780128; 4172855 and 4956122;

In addition to using 1-decene as a raw material, other raw materials are used to synthesize PAO patents. For example, US Patent No. 4956122 uses ethylene and higher olefins to copolymerize, and can obtain PAO products with a viscosity of 2 to 100 cSt at 100 ° C and a wide viscosity range. . Olefin mixtures of 1-octene, 1-decene and 1-dodecene can also be used to prepare PAO, such as patents CN1505643A and 101102982A. Chinese patent CN103100419A adopts two components of supported organoaluminum compound and proton donor as a catalyst system to carry out the oligomerization reaction of mixed decene, and the conversion rate of mixed decene is greater than 50%, but the performance of the product is not checked. describe. In the international publication WO2006/071135A1 patent, α-olefins are isomerized and oligomerized into higher olefins or a mixture thereof under the action of a catalytic system Al(O)HClTBCh.

Viscosity index (VI) indicates the extent to which the viscosity of any fluid changes with temperature. The higher the viscosity index, the less the fluid viscosity is affected by temperature. my country began to produce synthetic hydrocarbon oil as early as the 1970s, but wax cracking olefins were mostly used, and the product had a low viscosity index and poor thermal stability. In the early 1990s, in order to improve the performance of lubricating oil, Mobil Oil Company developed the HVI-PAO process using C ₆ -C ₂₀ linear α-olefins as raw materials to produce high viscosity index lubricating oil under polymerization conditions. Viscosity index is an important performance index of lubricating oil base oil. Patent CN1948243A provides a method for preparing high viscosity index poly-α-olefin synthetic oil. In a tank reactor, α-decene raw material is mixed with active chromium catalyst Contact, and react at 0.1-2.0MPa, 100-250°C for 2-20 hours; wherein the catalyst is a chromium-loaded type, and the product viscosity index is greater than 190, but this method requires linear α-olefins in α-decene raw materials The weight percentage should not be lower than 95%, the moisture content should be lower than 100ug/g, and the peroxide content should be lower than 5ug/g.

The above-mentioned method for preparing PAO uses expensive 1-decene as a raw material, and adopts a suitable catalytic system to synthesize a higher PAO product with a viscosity index, but uses non-linear olefins (such as mixed decenes or other branched α-olefins) As a raw material, the polymerization effect is poor, the conversion rate is low, and the product viscosity index is not high. The above method is not suitable for the synthesis of high viscosity index PAO products using nonlinear olefins as raw materials. At present, there are few reports on the preparation of PAO with high viscosity index directly by the polymerization of branched α-olefins.

Contents of the invention

The purpose of the present invention is to provide a method for preparing high viscosity index polyalpha-olefin synthetic oil by using cheap branched alpha-olefin as raw material and under the action of supported double active center catalyst. The polyalpha-olefin synthetic oil prepared by the method has good quality, high yield and low cost.

In order to achieve the above object, the present invention provides a method for preparing polyalphaolefin synthetic oil with a high viscosity index, comprising the following steps: adding an oligomerization catalyst to the raw material and reacting for 30 to 120 minutes at a temperature of 20 to 50°C; Catalyst, reaction product and unreacted α-olefin monomer, the reaction product is distilled and hydrogenated to obtain poly α-olefin synthetic oil;

The raw materials include branched α-olefins containing 4 to 14 carbon atoms, linear α-olefins containing 4 to 14 carbon atoms and olefins with intramolecular double bonds, and the weight of the raw materials is 100%. Linear α-olefins account for 0.1-91.0%, linear α-olefins account for 0.5-4.0%, and the balance is olefins with double bonds in the molecule.

The preparation of described oligomerization catalyst:

Using the step-by-step impregnation method, first select the metal salt corresponding to the metal oxide, one of the active components, to dissolve in deionized water, impregnate the carrier with the obtained metal salt solution, stir at 25-50°C for 30-180 minutes, and dry. Take the above-mentioned dried carrier, place it in a muffle furnace for high _- temperature roasting, and if necessary, further reduce the high-valent metal oxide to low priced metal oxides. Then add the above catalyst precursor into another organic solvent of inorganic metal salt for loading, for example, solvents such as toluene, acetone, and chlorophenylisopropanol, to obtain a supported double-active center catalyst, which is then stored for future use. In the preparation step of the above catalyst, the metal salts corresponding to the metal oxides are soluble vanadium salts such as vanadium nitrate, vanadyl oxalate, and vanadyl sulfate; soluble chromium salts such as chromium nitrate, chromium acetate, and chromium sulfate.

Distillation and hydrogenation of reaction products:

In the method provided by the present invention, there is no special requirement for the distillation and hydrogenation process of the reaction product, and the distillation process can adopt atmospheric and vacuum distillation equipment commonly used in the art, as long as it can realize the unpolymerized monomer and dimer, Different products such as trimers and oligomers above tetramers can be separated. Similarly, there are no special requirements for the hydrogenation process, as long as the purpose of product hydrogenation can be achieved, commonly used hydrogenation catalysts, equipment, process conditions, etc. can be used.

According to the method for preparing polyalpha-olefin synthetic oil with high viscosity index in the present invention, the branched alpha-olefin preferably accounts for 5-80%.

In the method for preparing polyalpha-olefin synthetic oil with high viscosity index described in the present invention, the branched alpha-olefin more preferably accounts for 15-60%.

The preparation method of the polyalpha-olefin synthetic oil of high viscosity index described in the present invention, described branched alpha-olefin is preferably selected from 2-butyl-1-hexene, 3-propyl-1-heptene, 4-Ethyl-1-octene, 5-methyl-1-nonene, 4-butyl-1-decene, 3-butyl-1-decene, 2-ethyl-1-dodecene and at least one of the group consisting of 6-ethyl-1-dodecene.

According to the method for preparing poly-α-olefin synthetic oil with high viscosity index in the present invention, the average number of carbon atoms of the branched α-olefin is preferably 8.9-12.5.

The preparation method of the polyalpha-olefin synthetic oil of high viscosity index described in the present invention, described oligomerization catalyst preferably comprises carrier and dual active component, and described dual active component preferably comprises metal oxide and Lewis acid type metal salt .

In the method for preparing polyalpha-olefin synthetic oil with high viscosity index according to the present invention, the Lewis acid type metal salt is preferably selected from the group consisting of AlCl ₃ , FeCl ₃ , SnCl ₄ , TiCl ₄ and ZnCl ₂ at least one.

In the method for preparing polyalphaolefin synthetic oil with high viscosity index according to the present invention, the metal oxide is preferably V ₂ O ₅ and/or CrO.

In the method for preparing polyalphaolefin synthetic oil with a high viscosity index according to the present invention, the carrier is preferably at least one selected from the group consisting of silica, aluminum oxide, chromatography silica gel, and molecular sieves.

In the method for preparing polyalphaolefin synthetic oil with high viscosity index according to the present invention, the molecular sieve is preferably MCM-41, MCM-48 or SBA-15.

According to the method for preparing polyalphaolefin synthetic oil with high viscosity index in the present invention, the reaction temperature is preferably 25-35° C., and the reaction time is preferably 60-100 min.

Compared with the prior art, the beneficial effect of the preparation method of the polyalpha-olefin synthetic oil provided by the present invention is:

(1) Use cheap branched α-olefins as synthetic raw materials to replace expensive 1-decene polymerization to prepare PAO with a high viscosity index. The branched α-olefins used can be selected from the preparation of linear α-olefins, such as 1-hexene , 1-octene, 1-decene, or high-carbon α-olefins (C ₁₂ ~ C ₂₀ ⁺ ) by-products; or from the decene plant, the product is then separated by column chromatography silica gel filtration to remove spent catalysts, etc. Impurities. Using the branched-chain α-olefin as a synthetic raw material can not only utilize by-products to improve utilization, but also use self-produced decene instead of expensive 1-decene to polymerize PAO with a high viscosity index, reducing costs and increasing economic benefits.

(2) The polyalpha-olefin obtained by the preparation method has a higher viscosity index (kinematic viscosity>40cSt at 100°C, viscosity index>150), good quality and high yield; the process is easy to operate and the process is improved economy.

(3) The preparation method uses a supported double-active center catalyst, which is weaker in activity for active branched-chain α-olefins than conventional homogeneous catalysts. Controlled polymerization can be achieved by adjusting the type and ratio of metals The purpose of the degree, the preparation is simple, and the operability is strong.

Detailed ways

The present invention is further described in detail by examples below, but these examples should not be considered as limiting the present invention.

The preparation of embodiment 1 oligomerization catalyst

8g of silica (pore volume 0.50cm ³ /g, average pore diameter 2.0nm, specific surface area 158m ² /g) was impregnated in vanadium nitrate aqueous solution (vanadium loading was 0.20wt%), continuously stirred in a water bath at 25°C Soak for 30 minutes, filter, and vacuum dry at 100°C for 6 hours; place the silica carrier impregnated with vanadium nitrate in a muffle furnace for roasting, first raise the temperature to 120°C, keep the temperature for 2 hours, then raise the temperature to 350°C, keep the temperature for 1 hour, and continue to heat up to 450°C, keep the temperature constant for 6 hours, and finally cool down naturally under nitrogen. The obtained sample was immersed again in a toluene solution of aluminum trichloride (the Al loading was 12.00 wt%), continuously stirred and impregnated at room temperature for 2 hours, and vacuum-dried at 100°C for 6 hours to obtain an oligomerization catalyst for storage until use.

Embodiment 2 Preparation of oligomerization catalyst

8g of silica (pore volume 0.58cm ³ /g, average pore diameter 12.5nm, specific surface area 100m ² /g) was impregnated in vanadyl oxalate aqueous solution (vanadium loading was 0.58wt%), continuously in a 45°C water bath Stir and impregnate for 50 minutes, filter, and vacuum dry at 100°C for 6h; put the silica carrier impregnated with vanadyl oxalate in a muffle furnace for roasting, first raise the temperature to 120°C, keep the temperature for 2h, then raise the temperature to 350°C, keep the temperature for 1h, Continue to heat up to 450°C, keep the temperature constant for 6h, and finally cool down naturally under nitrogen. The obtained sample was again immersed in an isopropanol solution of titanium tetrachloride (Ti loading was 10.68wt%), impregnated with continuous stirring at room temperature for 2 hours, and vacuum-dried at 100°C for 6 hours to obtain an oligomerization catalyst for storage until use.

The preparation of embodiment 3 oligomerization catalyst

Immerse 10g of aluminum oxide (γ-alumina, with a pore volume of 1.34cm ³ /g, an average pore diameter of 20nm, and a specific surface area of 220m ² /g) in an aqueous solution of chromium acetate (with a chromium loading of 12.00wt%), 25 Continuous stirring and impregnation in a water bath at ℃ for 60 minutes, filtering, and vacuum drying at 100 ℃ for 6 hours; put the aluminum oxide carrier impregnated with chromium acetate in a muffle furnace for calcination, first raise the temperature to 120 ℃, keep the temperature for 2 hours, and then raise the temperature to 350 ℃ , keep the temperature for 1h, continue to heat up to 550°C, keep the temperature for 6h, and finally cool down naturally under nitrogen to 200-300°C, pass in reducing gas H ₂ for 1-3h, and reduce the contained chromium oxides to low-priced chromium oxide. The obtained sample was immersed again in an isopropanol solution of titanium tetrachloride (0.10wt% Ti loading), impregnated with continuous stirring at room temperature for 4 hours, and vacuum-dried at 100° C. for 6 hours to obtain an oligomerization catalyst for storage until use.

Embodiment 4 Preparation of oligomerization catalyst

Immerse 10g of aluminum oxide (γ-alumina, with a pore volume of 1.34cm ³ /g, an average pore diameter of 20nm, and a specific surface area of 220m ² /g) in an aqueous solution of chromium nitrate (with a chromium loading of 11.56wt%) at 25°C Stir and impregnate continuously in a water bath for 70 minutes, filter, and vacuum-dry at 100°C for 6 hours; put the aluminum oxide carrier impregnated with chromium nitrate in a muffle furnace for roasting, first raise the temperature to 120°C, keep the temperature for 2 hours, and then raise the temperature to 350°C, Keep the temperature constant for 1 hour, continue to heat up to 550°C, keep the temperature constant for 6 hours, and finally cool down naturally under nitrogen to 200-300°C, and pass in reducing gas CO for 1-3 hours to reduce the contained chromium oxide to low-priced chromium oxide . The obtained sample was immersed again in an isopropanone solution of ferric chloride (0.24 wt% Fe loading), impregnated with continuous stirring at room temperature for 4 hours, and vacuum-dried at 100° C. for 6 hours to obtain an oligomerization catalyst for storage until use.

Embodiment 5 Preparation of oligomerization catalyst

Immerse 10g of SBA-15 molecular sieve (pore volume 5.2cm ³ /g, average pore diameter 3.9nm, specific surface area 500m ² /g) in chromium sulfate aqueous solution (chromium loading 4.20wt%), and continuously stir in a water bath at 25°C Immerse for 80min, filter, and vacuum dry at 100°C for 6h; place the SBA-15 molecular sieve carrier impregnated with chromium sulfate in a muffle furnace for roasting, first raise the temperature to 120°C, keep the temperature for 2h, then raise the temperature to 350°C, keep the temperature for 1h, continue Raise the temperature to 550°C, keep the temperature constant for 6 hours, and finally cool down to 200-300°C naturally under nitrogen, and pass in reducing gas CO for 1-3 hours to reduce the contained chromium oxides to low-priced chromium oxides. The obtained sample was immersed again in a toluene solution of zinc chloride (the loading capacity of Zn was 11.20wt%), continuously stirring and impregnating at room temperature for 4 hours, and vacuum drying at 100° C. for 6 hours to obtain an oligomerization catalyst for storage until use.

Embodiment 6 Preparation of oligomerization catalyst

Immerse 10g of MCM-41 molecular sieve (pore volume 1.20cm ³ /g, average pore diameter 3.20nm, specific surface area 1000m ² /g) in vanadyl sulfate aqueous solution (vanadium loading is 0.38wt%), continuously in a 45°C water bath Stir and impregnate for 3 hours, filter, and vacuum dry at 100°C for 6 hours; put the MCM-41 carrier impregnated with vanadyl sulfate in a muffle furnace for roasting, first raise the temperature to 120°C, keep the temperature for 2h, then raise the temperature to 350°C, keep the temperature for 1h, Continue to heat up to 450°C, keep the temperature constant for 6h, and finally cool down naturally under nitrogen. The obtained sample was again immersed in a toluene solution of tin tetrachloride (Sn loading was 0.86wt%), impregnated with continuous stirring at room temperature for 4 hours, and vacuum-dried at 100°C for 6 hours to obtain an oligomerization catalyst for storage until use.

Example 7

With the catalyst 3.02g that embodiment 1 makes, under nitrogen protection, join in the three-necked round-bottomed flask of 500mL drying, then add 120mL raw material in flask, its composition is branched α-olefin 91% (3-propyl -1-heptene 22.2%, 4-ethyl-1-octene 25.2%, 5-methyl-1-nonene 30.6%, 2-butyl-1-hexene 6.2%, 2-ethyl-1 -dodecene 6.8%), linear α-olefins 4.0% (1-decene 4.0%), olefins with intramolecular double bonds or "internal" olefins 5.0% (5-decene 2.3%, 3-methyl -4-nonene 1.1%, 2-ethyl-3-octene 1.6%), under the condition of water bath 20 ℃, stir the polymerization reaction for 30min, after the reaction, filter and separate the catalyst, distill to remove the monomer and dimer , the product was obtained after hydrogenation, and the product was collected for performance testing, as shown in Table 1.

Example 8

With the catalyst 3.02g that embodiment 1 makes, under nitrogen protection, join in the three-neck round bottom flask of 500mL drying, then add 120mL raw material in flask, its composition is branched α-olefin 88% (3-propyl -1-heptene 20.7%, 4-ethyl-1-octene 26.2%, 5-methyl-1-nonene 31.6%, 2-butyl-1-decene 9.5%), linear alpha-olefin 3.4% (1-octene 3.4%), olefins with intramolecular double bonds, that is, "internal" olefins 8.6% (5-decene 5.6%, 3-methyl-4-nonene 3.0%), in a water bath at 35°C Under the conditions, the polymerization reaction was stirred for 30 minutes. After the reaction, the catalyst was separated by filtration, the monomer and dimer were removed by distillation, and the product was obtained after hydrogenation. The product was collected for performance testing, as shown in Table 1.

Example 9

The catalyst 3.02g that embodiment 1 is made, under nitrogen protection, join in the three-necked round-bottomed flask of 500mL drying, then add 120mL raw material in flask, its composition is branched α-olefin 86.9% (3-propyl -1-heptene 18.5%, 4-ethyl-1-octene 24.2%, 3-butyl-1-decene 27.6%, 2-ethyl-1-dodecene 16.6%), linear α- Olefins 0.5% (1-dodecene 0.5%), olefins with intramolecular double bonds, that is, "internal" olefins 12.6% (5-decene 8.3%, 3-methyl-6-dodecene 4.3%), in In a water bath at 50°C, the polymerization reaction was stirred for 30 minutes. After the reaction, the catalyst was separated by filtration, the monomer and dimer were removed by distillation, and the product was obtained after hydrogenation. The product was collected for performance testing, as shown in Table 1.

Example 10

With the catalyst 3.02g that embodiment 2 makes, under the protection of nitrogen, join in the 500mL dry three-neck round bottom flask, add 120mL raw material in the flask again, its composition is branched α-olefin 90.2% (4-ethyl -1-octene 35.2%, 4-butyl-1-decene 30.6%, 2-butyl-1-hexene 20.1%), linear α-olefin 3.8% (1-decene 3.8%), with Olefins with double bonds in the molecule, that is, 6% "internal" olefins (4.3% for 5-decene, 1.7% for 4-octene), were stirred and polymerized for 30 minutes in a water bath at 25°C. After the reaction, the catalyst was separated by filtration. The monomer and dimer were removed by distillation, and the product was obtained after hydrogenation, and the product was collected for performance testing, as shown in Table 1.

Example 11

With the catalyst 3.02g that embodiment 2 makes, under nitrogen protection, join in the three-necked round bottom flask of 500mL dryness, then add 120mL raw material in flask, its composition is branched α-olefin 80% (3-propyl -1-heptene 32.5%, 4-ethyl-1-octene 25.2%, 2-ethyl-1-tetradecene 22.3%), linear α-olefin 3.6% (1-decene 3.6%), Alkenes with intramolecular double bonds, that is, "internal" alkenes 16.4 (5-decene 8.9%, 6-dodecene 3.2%, 3-methyl-4-nonene 4.3%), in a water bath at 25 ° C, stirring The polymerization reaction was 60 minutes. After the reaction, the catalyst was separated by filtration, the monomer and dimer were removed by distillation, and the product was obtained after hydrogenation. The product was collected for performance testing, as shown in Table 1.

Example 12

With the catalyst 3.02g that embodiment 2 makes, under nitrogen protection, join in the three-necked round-bottomed flask of 500mL drying, then add 120mL raw material in flask, its composition is branched α-olefin 60% (3-propyl -1-heptene 30.2%, 4-ethyl-1-octene 29.8%), linear α-olefins 3.9% (1-decene 3.4%, 1-octene 0.6%), with intramolecular double bonds The olefin is "internal" olefin 36.1% (5-decene 30.3%, 3-methyl-4-nonene 5.8%), in a water bath at 25 ° C, the polymerization reaction was stirred for 120 minutes, after the reaction, the catalyst was separated by filtration. The monomer and dimer were removed by distillation, and the product was obtained after hydrogenation, and the product was collected for performance testing, as shown in Table 1.

Example 13

With the catalyst 3.02g that embodiment 3 makes, under nitrogen protection, join in the three-necked round-bottomed flask of 500mL drying, then add 120mL raw material in flask, its composition is branched α-olefin 40% (3-propyl -1-heptene 40%), linear α-olefins 4.0% (1-decene 4.0%), olefins with intramolecular double bonds that are "internal" olefins 56% (5-decene 40.6%, 2-methanol Base-4-decene 5.6%, 3-methyl-4-nonene 9.8%), under the condition of water bath 28 ℃, stirring polymerization reaction 100min, after the reaction, filter and separate the catalyst, distill to remove the monomer and dimerization Body, after hydrogenation to obtain the product, collect the product for performance testing, see Table 1.

Example 14

With the catalyst 3.02g that embodiment 4 makes, under nitrogen protection, join in the three-necked round bottom flask of 500mL dryness, then add 120mL raw material in flask, its composition is branched α-olefin 35% (5-methyl -1 nonene 20.6%, 2-butyl-1-hexene 6.2%, 2-ethyl-1-dodecene 8.2%), linear α-olefin 2.8% (1-dodecene 2.8%), Olefins with intramolecular double bonds, that is, "internal" olefins 62.2% (5-decene 42.3%, 3-methyl-4-nonene 3.1%, 2-ethyl-3-octene 16.8%), in a water bath for 25 Under the condition of ℃, the polymerization reaction was stirred for 60 minutes. After the reaction, the catalyst was separated by filtration, the monomer and dimer were removed by distillation, and the product was obtained after hydrogenation. The product was collected for performance testing, as shown in Table 1.

Example 15

The catalyst 3.02g that embodiment 5 is made, under the protection of nitrogen, join in the 500mL dry three-neck round bottom flask, then add 120mL raw material in the flask, its composition is branched α-olefin 15% (4-ethyl -1-octene 15%), linear α-olefins 3.7% (1-octene 3.4%, 1-decene 0.3%), olefins with intramolecular double bonds, that is, "internal" olefins 81.3% (5-decene 45% ene, 34.6% 3-methyl-4-nonene, 1.7% 2-ethyl-3-octene), in a water bath at 25 ° C, the polymerization reaction was stirred for 80 minutes. After the reaction, the catalyst was separated by filtration. The monomer and dimer were removed by distillation, and the product was obtained after hydrogenation, and the product was collected for performance testing, as shown in Table 1.

Example 16

With the catalyst 3.02g that embodiment 6 makes, under nitrogen protection, join in the three-necked round-bottomed flask of 500mL drying, then add 120mL raw material in flask, its composition is branched α-olefin 0.1% (6-ethyl -1-dodecene 0.1%), linear α-olefins 3.5% (1-decene 3.5%), olefins with intramolecular double bonds, that is, "internal" olefins 96.4% (5-decene 56.3%, 3- Methyl-4-nonene 23.1%, 2-ethyl-3-octene 5.2%, 2-methyl-5-decene 11.8%), in a water bath at 25 ° C, the polymerization reaction was stirred for 60 minutes, after the reaction , the catalyst was separated by filtration, the monomer and dimer were removed by distillation, and the product was obtained after hydrogenation. The product was collected for performance testing, as shown in Table 1.

Comparative example 1

8 g of silicon dioxide were impregnated in a toluene solution of aluminum trichloride (0.4 wt % aluminum loading), impregnated with continuous stirring at room temperature for 4 h, and dried in vacuum at 100° C. for 6 h. The obtained catalyst 3.02g, under the protection of nitrogen, is added in the dry three-neck round bottom flask of 500mL, then adds 120mL raw material in the flask, and its composition is branched α-olefin 5% (2-butyl-1-hexyl olefins 5%), linear α-olefins 3.4% (1-decene 3.4%), olefins with intramolecular double bonds, that is, "internal" olefins 91.6% (5-decene 79.2%, 3-methyl-4- Nonene 12.4%), in a water bath at 25°C, the polymerization reaction was stirred for 60 minutes. After the reaction, the catalyst was separated by filtration, the monomer and dimer were removed by distillation, and the product was obtained after hydrogenation. The product was collected for performance testing, as shown in the table 1.

Comparative example 2

Immerse 8g of silica in vanadyl oxalate aqueous solution (the vanadium load is 0.36wt%), continuously stir and impregnate in a water bath at 45°C for 3h, filter, and dry in vacuum at 100°C for 6h; the silica carrier impregnated with vanadyl oxalate Put it in a muffle furnace for roasting, first raise the temperature to 120°C, keep the temperature for 2h, then raise the temperature to 350°C, keep the temperature for 1h, continue to raise the temperature to 450°C, keep the temperature for 6h, and finally cool down naturally under nitrogen. The obtained catalyst 3.02g, under the protection of nitrogen, is added in the dry three-neck round bottom flask of 500mL, then adds 120mL raw material in the flask, and its composition is branched α-olefin 90.5% (3-propyl group-1-heptane ene 46.3%, 4-ethyl-1-octene 15.2%, 5-methyl-1 nonene 20.6%, 2-ethyl-1-dodecene 8.4%), linear α-olefin 3.2% (1 -decene 3.2%), alkenes with intramolecular double bonds or "internal" alkenes 6.3% (5-decene 2.5%, 3-methyl-4-nonene 3.1%, 2-ethyl-3-octene 0.7%), under the condition of 25 ℃ of water bath, stirring polymerization reaction 60min, after reaction finishes, filter and separate catalyst, distill and remove monomer and dimer, obtain product after hydrogenation, collect product and carry out performance test, see table 1.

Table 1 Product performance parameters

As can be seen from Table 1, adopting the preparation method of polyalpha-olefin synthetic oil provided by the present invention, using cheap branched alpha-olefin as raw material, under the action of supported double active center catalyst, the polyalpha-olefin synthetic oil prepared has relatively High viscosity index (kinematic viscosity at 100°C > 40cSt, viscosity index > 150), good viscosity-temperature performance and high conversion rate.

Certainly, the present invention also can have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes And deformation should belong to the protection scope of the present invention.

Claims (8)

1. A preparation method of polyalpha-olefin synthetic oil with high viscosity index, is characterized in that, comprises the following steps: add oligomerization catalyst in raw material, react 30～120min under the condition of 20～50 ℃; Separation catalyst, Reaction products and unreacted α-olefin monomers, the reaction products are distilled and hydrogenated to obtain poly-α-olefin synthetic oil; The raw materials include branched α-olefins containing 4 to 14 carbon atoms, linear α-olefins containing 4 to 14 carbon atoms and olefins with intramolecular double bonds, and the weight of the raw materials is 100%. Alkenized α-olefins account for 0.1-91.0%, linear α-olefins account for 0.5-4.0%, and the balance is olefins with double bonds in the molecule; The oligomerization catalyst includes a carrier and a dual active component, the dual active component includes a metal oxide and a Lewis acid metal salt, and the Lewis acid metal salt is selected from AlCl ₃ , FeCl ₃ , SnCl ₄ , TiCl ₄ and at least one of the group consisting of ZnCl ₂ , the metal oxide is V ₂ O ₅ and/or CrO. 2. the preparation method of the polyalpha-olefin synthetic oil of high viscosity index according to claim 1 is characterized in that, described branched alpha-olefin accounts for 5-80%. 3. the preparation method of the polyalpha-olefin synthetic oil of high viscosity index according to claim 2 is characterized in that, described branched alpha-olefin accounts for 15-60%. 4. the preparation method of the polyalpha-olefin synthetic oil of high viscosity index according to claim 1 is characterized in that, described branched alpha-olefin is selected from 2-butyl-1-hexene, 3-propyl -1-heptene, 4-ethyl-1-octene, 5-methyl-1-nonene, 4-butyl-1-decene, 3-butyl-1-decene, 2-ethyl - at least one of the group consisting of 1-dodecene and 6-ethyl-1-dodecene. 5. the preparation method of the polyalpha-olefin synthetic oil of high viscosity index according to claim 1 or 4, is characterized in that, the average number of carbon atoms of described branched alpha-olefin is 8.9-12.5. 6. the preparation method of the polyalpha-olefin synthetic oil of high viscosity index according to claim 1, is characterized in that, described carrier is selected from the group that is formed by silica, aluminum oxide, chromatographic silica gel, molecular sieve at least one of the 7. the preparation method of the polyalpha-olefin synthetic oil of high viscosity index according to claim 6 is characterized in that, described molecular sieve is MCM-41, MCM-48 or SBA-15. 8. The method for preparing poly-α-olefin synthetic oil with high viscosity index according to claim 1, characterized in that, the reaction temperature is 25-35° C., and the reaction time is 60-100 min.