A bridged quinolinyl-indenyl metallocene catalyst for synthesizing high viscosity PAO

Abstract

The application provides a bridged quinoline-indene metallocene catalyst for synthesizing high-viscosity PAO. The metallocene catalyst claimed by the application has high raw material conversion rate when synthesizing poly-alpha-olefin, can be used for synthesizing high-viscosity PAO by using mixed raw materials, and can keep a very low pour point, and can be used in various fields such as industrial gear oil, lubricating oil and bearing oil.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering, and specifically discloses a bridged quinoline indene metallocene catalyst for synthesizing high-viscosity PAO. Background Technology

[0002] Polyalphaolefins (PAOs) are an important class of synthetic lubricant base oils. Originally developed to meet military needs, they are now widely used in aviation, automotive, and machinery industries. PAOs are obtained through the catalytic polymerization and hydrogenation of alpha-olefins. They possess a regular, sparse molecular structure, with trimers, tetramers, and pentamers as their main components. They exhibit excellent viscosity-temperature properties, thermal stability, low volatility, and low-temperature fluidity, making them widely used as base oils for mid- to high-end lubricants. Based on viscosity, PAOs can be classified into high-viscosity PAOs, medium-viscosity PAOs, and low-viscosity PAOs. High-viscosity PAOs have a viscosity range of 40–1000 mg / L. 2 / s, can be used in harsh lubrication applications with high load and strong shear, and is usually used in combination with low viscosity base oils to formulate industrial gear oils and automotive gear oils with different ISO viscosity grades. It can also be used as automotive gear and heavy-duty transmission oil, high-temperature industrial gear and circulating oil, industrial hydraulic fluid, gas turbine oil for land applications, etc.

[0003] Catalysts used for the synthesis of PAO mainly include aluminum trichloride catalysts, boron trifluoride catalysts, Ziegler-Nata catalysts, metallocene catalysts, and ionic liquid catalysts. Metallocene catalysts, due to their single active center and high catalytic activity, have become a research hotspot in recent years and have been successfully applied in industrial production. PAO molecules synthesized using metallocene catalysts have a unique comb-like structure and lack upright side chains, which determines that they have a higher viscosity index and better thermal stability compared to conventional PAO products.

[0004] Co-catalysts are an important component of metallocene catalytic systems, generally classified into two main categories: alkylaluminoxanes and organoborides. Alkylaluminoxanes include methylaluminoxanes, ethylaluminoxanes, butylaluminoxanes, and mixtures thereof. These co-catalysts require a certain proportion in the catalytic system to exert their catalytic effect; typically, the Al / Zr ratio is 500:1, 1000:1, or even 1500:1 and 2000:1. Alkylaluminoxanes are extremely reactive, reacting violently with moisture and oxygen in the air, accompanied by strong exothermic reactions. Therefore, the large quantities required, their unstable nature, and their high cost limit the application of this type of co-catalyst.

[0005] The performance of PAO products is determined by the degree of polymerization and molecular weight distribution of the oligomer products. Generally, the viscosity and thermal stability of the product increase with the increase of the carbon number of the PAO molecule, while more side chain structures and relatively short linear segments are beneficial for PAO to maintain good flowability at low temperatures. By changing the composition of the catalyst system and the reaction conditions, the product distribution of the oligomerization reaction can be controlled, thereby adjusting the performance of the PAO product.

[0006] For example, patent CN 105885929 discloses a method for reducing the dimer content in the product by adding a chain shuttle. This method uses metallocene as the main catalyst, organoborides as the co-catalyst, and coal-to-α-olefins as the reactants. By adding the chain shuttle dialkylzinc, the dimer content in the polymerization product is significantly reduced, the yield of lubricating oil base oil components is improved, and the resulting product has good low-temperature fluidity.

[0007] US Patent 6548724 discloses a method for preparing low-viscosity metallocene polyalphaolefins (PAOs) using metallocene catalysis on 1-decene. Using a non-bridging metallocene catalyst, the synthesized low-viscosity PAO exhibits excellent viscosity-temperature properties; however, the yield of the dimer reached a maximum of 49% during the synthesis process.

[0008] US Patent 8207390 discloses a method for catalytically synthesizing low-viscosity PAO using an alkyl-substituted dicyclopentadienyl zirconium dichloride and an organoboronide system. Under certain temperature and hydrogen pressure conditions, the viscosity of the synthesized product can reach 4.36 mm. 2 / s, but the yield of dimer is as high as 47%.

[0009] Patent US8748361 describes the synthesis of low-viscosity PAO using a hydrogenated bridged metallocene catalyst system—dimethylsilyl tetrahydroindenyl dichloride and organoborides. The product viscosity was 6.2 mm at 140 °C. 2 / s, at which point the yield of the dimer is approximately 38.7%, and the catalyst activity is approximately 14 kg product / g catalyst.

[0010] Patent US2015 / 0344598 describes the synthesis of low-viscosity PAO using a hydrogenated vinyl-bridged metallocene catalyst—vinyltetrahydroindenezirconium dichloride and organoboronides. Under a certain hydrogen pressure, the catalyst activity can reach 80 kg product / g catalyst, but about 5% of the feedstock is saturated with alkanes.

[0011] Patent CN 1252097 describes the use of a transition metal catalyst containing a large volume ligand and an activator consisting of an organoaluminum compound or a hydrocarbon boron compound or a mixture thereof to polymerize α-olefins, resulting in an oligomer oil comprising a first fraction with a desired composition and a second fraction with an undesirable composition. This method can maximize control over the chemical process, reduce the degree of double bond isomerization of olefins in the feedstock, and increase the yield of olefins converted into oligomer oils.

[0012] Patent CN 101501083 describes the preparation of high-viscosity hydrogenated PAO using an unbridged substituted bis(cyclopentadienyl) transition metal catalyst and a noncoordinated anion activator in the presence of hydrogen, with a kinematic viscosity greater than 20 mm at 100 °C. 2 / s, pour point below -40 ℃.

[0013] Patent CN 108559012 discloses a metallocene catalyst structure for the synthesis of PAO, comprising a substituted aromatic group, a bridging atom, an unsubstituted or 3-monosubstituted or 3,6-disubstituted 5H-indeno[1,2-b]pyridyl group or an unsubstituted or 3-monosubstituted or 3,6-disubstituted 5H-indeno[1,2-b]thiopyranyl group, and a metal coordination group. The catalyst preparation method is simple, low-cost, structurally stable, and exhibits high catalytic efficiency; the product has high viscosity and a low pour point.

[0014] Patent CN113583158 discloses a metallocene catalyst containing a dihydroindo[1,2-b]indole structure. Using this catalyst, along with an alkylaluminum co-catalyst and a chain shuttle, PAO can be synthesized. The viscosity of PAO can be adjusted by regulating the reaction conditions or changing the type of chain shuttle.

[0015] Current technologies for synthesizing PAO require a single α-olefin as a raw material or very high purity. Furthermore, the high pour point of PAO synthesized with high viscosity makes it prone to solidification at low temperatures, limiting its application. In most metallocene-catalyzed polymerization reactions of α-olefins, the product contains a high amount of dimers, but these dimers have very low flash points and are considered useless components in PAO, requiring removal by vacuum distillation, resulting in low product yields. Therefore, developing a new catalyst to reduce dimer selectivity, improve product yield, maintain a low pour point at high viscosity, and ensure good product flowability is a key technical challenge. Summary of the Invention

[0016] To address the aforementioned technical problems, this invention discloses a catalyst for synthesizing high-viscosity polyalphaolefins (PAOs) using a bridged quinoline-indene metallocene catalyst and its application. This invention relates to a catalyst system for synthesizing high-viscosity PAOs, comprising a bridged quinoline-indene metallocene main catalyst and an alkylaluminum co-catalyst, and its application. The metallocene catalyst claimed in this invention exhibits high feed conversion rates during the synthesis of PAOs, and can utilize mixed feedstocks to synthesize high-viscosity PAOs while maintaining a very low pour point. It can be used in various fields such as industrial gear oils, lubricating oils, and bearing oils.

[0017] The present invention adopts the following technical solution:

[0018] This invention discloses a metallocene catalyst comprising a bridged quinoline-indene ligand and a metal. When this catalyst system, composed of a bridged quinoline-indene metallocene as the main catalyst and alkylaluminum as a co-catalyst, is used to synthesize polyalphaolefin (PAO), it exhibits advantages such as high activity, high feedstock utilization, the ability to prepare high-viscosity PAO using mixed feedstocks, high product yield, low product pour point, and a wide operating temperature range.

[0019] A metallocene catalyst having the following structure (Formula I):

[0020]

[0021] Formula I

[0022] Where M is Ti, Zr or Hf, Z is Si or C, X and X' are ligands that form coordinate bonds with Z, and Y and Y' are ligands that form coordinate bonds with M.

[0023] Preferably, X and X' are each independently selected from the group consisting of amino, fluorine, bromine, iodine, chlorine, methyl, ethyl, propyl, n-butyl and isobutyl, and Y and Y' are each independently selected from the group consisting of amino, fluorine, bromine, iodine, chlorine, methyl, ethyl, propyl, n-butyl and isobutyl.

[0024] A method for synthesizing polyα-olefins using a metallocene catalyst: using α-olefins as raw materials and a metallocene catalyst as the main catalyst, a polymerization reaction is carried out.

[0025] Preferably, the α-olefin is a single or mixed α-olefin; a co-catalyst is also added to the synthesis method.

[0026] Preferably, the cocatalyst is an organoboron reagent or an alkylaluminoxane reagent.

[0027] Preferably, the organoboron reagent is selected from one or more of [Ph3C][B(C6F5)4], [PhMe2NH][B(C6F5)4], and B(C6F5)3; the alkylaluminoxane reagent is selected from one or more of methylaluminoxane, ethylaluminoxane, n-propylaluminoxane, and n-butylaluminoxane.

[0028] Preferably, the molar ratio of aluminum in the co-catalyst to the metal in the main catalyst is 10-1000:1; or the molar ratio of boron in the co-catalyst to the metal in the main catalyst is 1-300:1; the α-olefin is selected from one or a mixture of several of 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetracene, and 1-tetradecene.

[0029] The advantages of this invention are:

[0030] For the first time, a bridged quinoline-indene metallocene catalyst system was used to prepare high-viscosity PAO. The product has high viscosity, low pour point, can utilize mixed α-olefin feedstocks, improves the yield of lubricating oil components, and has a high overall yield. Attached Figure Description

[0031] Figure 1 The 1H NMR spectrum of quinoline-indene ligand L1;

[0032] Figure 2 The hydrogen NMR spectrum of silicon-bridged ligand L2;

[0033] Figure 3 This is the 1H NMR spectrum of a silicon-bridged metallocene catalyst with ligands. Detailed Implementation

[0034] To make the above-mentioned features and advantages of the present invention more apparent and understandable, specific embodiments are described below in detail. Unless otherwise specified, the methods of the present invention are conventional methods in the art.

[0035] Example: Synthesis of silicon-bridged quinoline-indene zirconium dichloride

[0036] (1) Preparation of silicon-bridged ligands

[0037]

[0038] 0 o At temperature C, 2-aminobenzaldehyde (starting material 1, 2.42 g, 20 mmol) and 2,3-dihydro-1H-inden-1-one (starting material 2, 2.64 g, 20 mmol) were added to a reaction flask, followed by 50 mL of ethanol. KOH (112 mg, 20 mmol) was dissolved in a small amount of ethanol (20 mL) and slowly added. After the addition was complete, the temperature reached 78°C. o Reflux at C for 2 hours. Reduce the mother liquor to 0.o C, the pH was adjusted to neutral with 1 M hydrochloric acid solution, filtered, and a pale yellow solid was obtained. It was dissolved in ethyl acetate, dried over Na₂SO₄, and then crystallized from ethyl acetate / petroleum ether. Pure quinolinoindene ligand L1 (3.73 g, yield 86%) was obtained. The NMR spectrum and the structure of the compound were in perfect agreement, confirming the successful preparation of the compound.

[0039]

[0040] -78 o At C, a solution of n-butyllithium (0.8 ml, 2 mmol, hexane solvent) was slowly added dropwise to a 20 mL THF solution of ligand L1 (434 mg, 2 mmol). After the addition was complete, the mixture was allowed to return to room temperature and reacted overnight. The mother liquor was then cooled to -78°C. o C. Dichlorodimethylsilane (129 mg, 1 mmol) was slowly added dropwise. After the addition was complete, the reaction was allowed to proceed overnight at room temperature. The reaction was quenched with water, extracted with ethyl acetate, and crystallized from petroleum ether to obtain the silicon-bridged ligand L2 (1H NMR spectrum as shown). Figure 2 As shown in the figure, the yield is approximately 43%.

[0041] (2) Preparation of silicon-bridged ligand metallocene catalysts

[0042]

[0043] -78 o At C, a solution of n-butyllithium (0.8 ml, 2 mmol, hexane solvent) was slowly added dropwise to a 20 mL THF solution of ligand L2 (490 mg, 1 mmol). After the addition was complete, the mixture was allowed to return to room temperature and reacted overnight. The mother liquor was then cooled to -78°C. o C. Slowly add a 10 mL solution of THF containing zirconium tetrachloride (233 mg, 1 mmol). After the addition is complete, allow the mixture to return to room temperature and react overnight. After the solvent is removed, extract with toluene (15 × 3). Filter, and after drying the toluene extract, a small amount of brown solid (0.35 mg) of metallocene catalyst is obtained, yielding 51.2%. NMR results are as follows: Figure 3 As shown, a distinct alkenyl peak is observed at 6.2 ppm, indicating the formation of a product.

[0044] Application Example 1:

[0045] Catalyst preparation:

[0046] Weigh 30.6 mg of silicon-bridged quinoline zirconium chloride and dissolve it in 10 ml of toluene. Add 3 mL of 1.5 mol / LMAO / toluene solution (the molar ratio of aluminum in the co-catalyst to zirconium in the main catalyst is 100) and continue stirring for 30 min before use.

[0047] Synthetic polyalphaolefin products:

[0048] A 250 ml flask equipped with a magnetic stirrer was connected to a double-row pipeline. The air in the reaction flask was removed by evacuation, and the mixture was purged with high-purity nitrogen 3-4 times. 60 g of 1-decene was weighed, and the temperature was raised to 70°C. After 10 min, the pre-prepared catalyst solution was added to initiate the reaction. After 1 h of reaction, 10 ml of hydrochloric acid-ethanol solution (10 wt% hydrochloric acid, 1:9 volume ratio of hydrochloric acid to ethanol) was injected into the flask to terminate the reaction. The flask was washed three times with water, and its composition was analyzed by chromatography. The results are shown in Table 1.

[0049] Application Example 2:

[0050] Same as Application Example 1, except that the reaction temperature is 80°C. o C. The data results are shown in Table 1.

[0051] Application Example 3:

[0052] Same as Application Example 1, except that the reaction temperature is 90°C. o C. The data results are shown in Table 1.

[0053] Application Comparative Example 1:

[0054] Same as in Application Example 1, except that the main catalyst used is rac -Et(Ind)2ZrCl2, the results are shown in Table 1.

[0055] Application Comparative Example 2:

[0056] Same as in Application Example 2, except that the main catalyst used is rac -Et(Ind)2ZrCl2, the results are shown in Table 1.

[0057] Application Comparative Example 3:

[0058] Same as in Application Example 3, except that the main catalyst used is rac -Et(Ind)2ZrCl2, the results are shown in Table 1.

[0059] Application Example 4:

[0060] Similar to Application Example 1, except that the reaction raw materials are 30g of 1-decene and 30g of 1-octene. The data results are shown in Table 2.

[0061] Application Example 5:

[0062] Same as in Application Example 1, except that the reactants are 30g of 1-decene and 30g of 1-dodecene.

[0063] The data results are shown in Table 2.

[0064] Application Example 6:

[0065] Same as in Application Example 1, except that the reaction raw materials are 20g of 1-octene, 20g of 1-decene, and

[0066] 20g of 1-dodecene, the data results are shown in Table 2.

[0067] Application Comparative Example 4:

[0068] Same as in Application Example 4, except that the main catalyst used is rac -Et(Ind)2ZrCl2, the results are shown in Table 2.

[0069] Application Comparative Example 5:

[0070] Same as in Application Example 5, except that the main catalyst used is rac -Et(Ind)2ZrCl2, the results are shown in Table 2.

[0071] Application Comparative Example 6:

[0072] Same as in Application Example 6, except that the main catalyst used is rac -Et(Ind)2ZrCl2, the results are shown in Table 2.

[0073] Table 1 shows the composition, viscosity, and pour point analysis of the polymer products obtained from Application Examples 1-3 and Comparative Examples 1-3.

[0074]

[0075] *Table 1 shows the data after vacuum distillation.

[0076] As can be seen from the data in Table 1, the products obtained by preparing polyα-olefins using a silicon-bridged quinoline-indene metallocene catalyst are similar to those obtained using a classic bridged metallocene catalyst. rac Compared to -Et(Ind)2ZrCl2, while maintaining a similar viscosity, the product has a higher viscosity index and a higher product yield.

[0077] Table 2. Composition, viscosity, and pour point analysis of polymer products obtained from Application Examples 4-6 and Comparative Examples 4-6.

[0078]

[0079] *Table 2 shows the data after vacuum distillation.

[0080] As can be seen from the data in Table 2, the products obtained by preparing poly-α-olefins using silicon-bridged quinoline-indene metallocene catalysts with different raw materials are similar to those obtained by classic bridging metallocene catalysts. racCompared to -Et(Ind)2ZrCl2, the combined effective product yields of trimer, tetramer, pentamer and above are higher, and the product viscosity is higher and the pour point is lower.

[0081] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for synthesizing high-viscosity PAO using a bridged quinoline-indene metallocene catalyst, characterized in that, Polymerization reaction is carried out using α-olefins as raw materials and metallocene catalysts as the main catalysts; The α-olefin is a single or mixed α-olefin; a co-catalyst is also added to this synthesis method; The cocatalyst is an organoboron reagent or an alkylaluminoxane reagent; The organoboron reagent is selected from one or more of [Ph3C][B(C6F5)4], [PhMe2NH][B(C6F5)4], and B(C6F5)3; the alkylaluminoxane reagent is selected from one or more of methylaluminoxane, ethylaluminoxane, n-propylaluminoxane, and n-butylaluminoxane. The molar ratio of aluminum in the co-catalyst to the metal in the main catalyst is 10-1000:1; or the molar ratio of boron in the co-catalyst to the metal in the main catalyst is 1-300:1; the α-olefin is selected from one or a mixture of several of 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetracene, and 1-tetradecene. The structure of the metallocene catalyst is as follows: 。

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