Metallocene catalyst composition, and preparation method therefor and use thereof

Abstract

Provided in the present invention are a metallocene catalyst composition, and a preparation method therefor and the use thereof. The composition of the metallocene catalyst composition comprises a carbon-bridged metallocene compound and a substituted metallocene compound in a molar ratio of 10: 1.25-1.5, wherein the structure of the carbon-bridged metallocene compound is [RC(CH3)2(n-BuCp)]MCl2, and the structure of the substituted metallocene compound is [CH2=C(CH3)(n-BuCp)]2MCl2. The metallocene catalyst composition can catalyze the polymerization of ethylene and / or an α-olefin.

Description

A metallocene catalyst composition, its preparation method and application

[0001] Cross-reference information

[0002] This application claims priority to Chinese Patent Application No. 202411548856.2, entitled "A metallocene catalyst composition and its preparation method and application", filed on October 31, 2024, entitled "A metallocene catalyst composition and its preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention belongs to the fields of metallocene compounds and olefin polymerization, and specifically relates to a metallocene catalyst composition, its preparation method and application. Background Technology

[0004] Metallocene catalysts are a class of single-active-center organometallic complexes composed of transition metals or rare earth metals (especially Ti, Zr, or Hf) and at least one cyclopentadienyl ligand or its derivative. The chemical structure of metallocene catalysts is easily tunable, allowing for the customization of polymer properties, such as controlling molecular weight and distribution, and comonomer content, through catalyst structure design. Metallocene catalysts can catalyze the polymerization of ethylene, the stereoregular polymerization of α-olefins, and the copolymerization of ethylene and α-olefins, demonstrating great potential in the field of new material synthesis. Among them, ethylene octene copolymer elastomer (EOC) possesses excellent mechanical and processing properties, has been developed into a series of products, and has been widely applied.

[0005] Metallocene compounds are typically combined with boron compounds and organoaluminum compounds to form metallocene catalytic systems, which are commonly used as catalysts for olefin polymerization. The ligands in their metallocene structures play a crucial role in their structure, and their steric hindrance and electronic effects can be tuned over a wide range, resulting in catalysts with unique steric and electronic properties.

[0006] Metallocene catalysts composed of titanocene compounds, boron compounds, and organoaluminum compounds possess characteristics such as adjustable comonomer insertion amounts and microstructures. For example, CN1328580A discloses a bridged metallocene for olefin copolymerization, which is an organometallic catalyst containing an aryl-substituted bridging moiety. This complex contains a solubilized covalent bridging moiety comprising at least one hydrocarbon silyl substituent. The preparation methods for this type of compound all employ stepwise synthesis; the preparation routes are long, and the product yields are low. The structure of this metallocene is as follows.

[0007] Metallocene catalysts have the advantages of adjustable comonomer insertion amount and microstructure, high catalytic activity, narrow relative molecular weight distribution of the generated polymer, controllable polymer structure, and customizable polymer molecules. Therefore, they have great advantages in the synthesis of polyalphaolefin base oils in the field of lubricating oils, and can produce PAO base oils with controllable composition distribution.

[0008] CN101389668A discloses a bismetallocene catalyst, comprising a bridged bismetallocene and a non-bridged bismetallocene, wherein the metal in the metallocene compound can be titanium, zirconium, or hafnium; however, it does not provide a method for synthesizing the metallocene mixture, because the ligands of the two metallocene compounds are different, and it is not easy to synthesize the two metallocene compound components simultaneously in a one-pot method.

[0009] CN107636029A discloses a catalyst system comprising at least two metallocene compounds, one of which is a bridged monocyclopentadienyl Group 4 transition metal compound (restricted geometry), and the second is a dicyclopentadienyl Group 4 transition metal compound (bridged bis-metallocene or non-bridged bis-metallocene); however, it does not provide a method for synthesizing the metallocene mixture, and given that the ligands of the two metallocene compounds are different, it is not easy to synthesize the two metallocene compound components simultaneously in a one-pot method.

[0010] CN115210277A discloses an ethylene polymer, its preparation method, and a catalyst. The catalyst comprises a single-atom bridged metallocene compound (bridged bis-metallocene) having indenyl and cyclopentadienyl groups and an unbridged hafnium metallocene having two cyclopentadienyl groups (non-bridged bis-metallocene). However, the two metallocenes involve two cyclopentadienyl ligands, making it difficult to synthesize both metallocene compound components simultaneously in a one-pot process. Summary of the Invention

[0011] The present invention aims to provide a metallocene catalyst composition, its preparation method, and its application. This preparation method can produce the metallocene catalyst composition in a one-pot process with high yield, and the resulting metallocene catalyst composition can catalyze the polymerization of ethylene and / or α-olefins.

[0012] To achieve the above objectives, the present invention provides a method for preparing a metallocene catalyst composition, comprising the following steps:

[0013] (1) Under a protective gas atmosphere, n-BuLi solution was added to the reaction flask, cooled to -20℃ to 0℃, and then an amine compound was added and reacted for 12-48h. The solvent was removed to obtain amine lithium.

[0014] (2) Under conditions of -20℃ to 0℃, the amino lithium obtained in step (1) is mixed with a solvent, and 6,6-dimethyl-2-butylfulne and its derivatives are added at -70℃ to -100℃ under a protective gas atmosphere. The reaction is maintained at -70℃ to -100℃ for 1-4h, and then the temperature is raised to 20℃ to 30℃ for 24-100h.

[0015] (3) Add n-BuLi to the reaction solution of step (2) and react for 24-48h. After removing the solvent, add the solvent again and add MCl4·2THF at -70℃ to -90℃ under a protective gas atmosphere. Maintain the reaction at -70℃ to -90℃ for 1-4h, then raise the temperature to 20℃ to 30℃ and react for 24-72h. Remove the solvent, wash, filter and recrystallize to obtain the metallocene catalyst composition.

[0016] According to a specific embodiment of the present invention, preferably, the above preparation method includes the following steps:

[0017] (1) Under a protective gas atmosphere, n-BuLi solution was added to the reaction flask, cooled to -20℃ to -10℃, and then an amine compound was added and reacted for 24-36 h. The solvent was removed to obtain amine lithium.

[0018] (2) Under conditions of -20℃ to -10℃, the amino lithium obtained in step (1) is mixed with a solvent, and 6,6-dimethyl-2-butylfulne and its derivatives are added at -75℃ to -85℃ under a protective gas atmosphere. The reaction is maintained at -75℃ to -85℃ for 2-3 hours, and then the temperature is raised to 20℃ to 30℃ for 24-72 hours.

[0019] (3) Add n-BuLi to the reaction solution of step (2) and react for 36-48h. After removing the solvent, add the solvent again and add MCl4·2THF at -75℃ to -85℃ under a protective gas atmosphere. Maintain the reaction at -75℃ to -85℃ for 2-3h, then raise the temperature to 20℃ to 30℃ and react for 24-36h. Remove the solvent, wash, filter and recrystallize to obtain the metallocene catalyst composition.

[0020] According to a specific embodiment of the present invention, preferably, in step (1), the molar ratio of n-BuLi to the amine compound is 1:0.8-1, more preferably 1:0.9.

[0021] According to a specific embodiment of the present invention, preferably, in step (1), the reaction temperature is -20℃ to -10℃ and the reaction time is 24-30h.

[0022] According to a specific embodiment of the present invention, preferably, the molar ratio of n-BuLi in step (1) to the molar ratio of 6,6-dimethyl-2-butylfulne and its derivatives in step (2) is 1:0.8-1, more preferably 1:0.9.

[0023] According to a specific embodiment of the present invention, preferably, in step (2), after the addition of 6,6-dimethyl-2-butylene, the temperature is raised to 25°C and the reaction is carried out for 44-58 hours.

[0024] According to a specific embodiment of the present invention, preferably, the solvent used in step (2) is a mixture of n-hexane and tetrahydrofuran in a volume ratio of 3-6:1.

[0025] According to a specific embodiment of the present invention, preferably, in step (3), the molar ratio of n-BuLi to MCl4·2THF is 1:0.8-1, more preferably 1:0.9.

[0026] According to a specific embodiment of the present invention, preferably, the molar ratio of n-BuLi added in step (3) to 6,6-dimethyl-2-butylfulne and its derivatives in step (2) is 1:0.8-1, more preferably 1:0.9.

[0027] According to a specific embodiment of the present invention, preferably, the solvent added in step (3) is a mixture of n-hexane and tetrahydrofuran with a volume ratio of 3-6:1, more preferably a mixture of n-hexane and tetrahydrofuran with a volume ratio of 4-5:1.

[0028] According to a specific embodiment of the present invention, preferably, the amine compound is a C3-C6 amine compound, such as one or more of aromatic hydrocarbon amines, cycloalkane amines, and aliphatic hydrocarbon amines, and more preferably one or more of aniline, cyclohexylamine, and tert-butylamine.

[0029] According to a specific embodiment of the present invention, preferably, the metal element of the metallocene catalyst composition includes Ti and / or Zr.

[0030] According to a specific embodiment of the present invention, preferably, the 6,6-dimethyl-2-butylene is prepared by the following steps:

[0031] (1) Under the protection of a protective gas, n-BuBr was added dropwise to CpNa solution at -20 to 0℃ and reacted for 12-24 h to obtain n-BuC5H5;

[0032] (2) Under the protection of a protective gas, the n-BuC5H5 obtained in step (1) is mixed with acetone, and pyrrolidine is added at -20 to 0°C for 18-30 h to obtain 6,6-dimethyl-2-butylfulne.

[0033] According to a specific embodiment of the present invention, preferably, in the process of preparing 6,6-dimethyl-2-butylfulne, the molar ratio of CpNa to n-BuBr is 1:0.9-1, more preferably 1:0.95.

[0034] According to a specific embodiment of the present invention, preferably, in the process of preparing 6,6-dimethyl-2-butylene, the reaction temperature of step (1) is -20°C to 0°C.

[0035] According to a specific embodiment of the present invention, preferably, in the process of preparing 6,6-dimethyl-2-butylfulne, the molar ratio of n-BuC5H5 to acetone is 1:1.5-2.5, more preferably 1:2.

[0036] According to a specific embodiment of the present invention, preferably, in the process of preparing 6,6-dimethyl-2-butylene, the reaction temperature of step (2) is -20°C to 0°C.

[0037] According to a specific embodiment of the present invention, the preparation method of the above-mentioned metallocene catalyst composition includes the following specific steps:

[0038] (1) Under inert gas protection, n-BuLi solution (the reagent solvent is cyclohexane) was added to the reaction flask, cooled to -20℃ to -10℃, and the amine compound was slowly added dropwise with stirring. After the addition was completed, the reaction was carried out for 24-30 hours. The solvent was removed under vacuum to obtain amine lithium.

[0039] (2) Under conditions of -20℃ to -10℃, n-hexane and THF with a volume ratio of 3-6:1 are added to the product of step (1), stirred and dissolved, and under the protection of inert gas, 6,6-dimethyl-2-butylfulne is added at -75℃ to -85℃, and the reaction is maintained at -75℃ to -85℃ for 2-3h, and then the temperature is raised to room temperature (25℃) and stirred for 24-48h.

[0040] (3) Add n-BuLi to the reaction solution of step (2) and continue stirring for 36-48h; remove the solvent under vacuum, then add n-hexane and tetrahydrofuran, and under argon protection, slowly add MCl4·2THF at -75℃ to -85℃, and maintain the reaction at -75℃ to -85℃ for 2-3h; then naturally rise to room temperature and react for 24h.

[0041] (4) The solvent is removed by vacuum extraction, hexane is added for washing, and the mixture is filtered. After the solid precipitate is dried, a solid powder is obtained. The solid powder is then recrystallized with dichloromethane-hexane to obtain crystals, which are the metallocene catalyst composition.

[0042] The pure crystals obtained by the above preparation method have a metallocene composition yield of 54% or higher (based on metal content). Simultaneously, the pure metallocene composition can be used...1 ¹H NMR and MS were used to quantify the molecular structure and component ratio of the composition.

[0043] According to a specific embodiment of the present invention, the preparation method of the above-mentioned 6,6-dimethyl-2-butylene includes the following specific steps:

[0044] (1) Preparation of n-BuC5H5: Under inert gas protection, the THF solution of CpNa was added to the reaction flask and stirred and cooled at -20 to 0℃. n-BuBr was slowly added to the constant pressure dropping funnel, and a large amount of precipitate was formed. After the addition was completed, the reaction was stirred for 12-24h. Ice water was added and stirred. The precipitate was completely dissolved and the layers were separated. The organic phase was taken and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with saturated NaCl aqueous solution and distilled water. The mixture was dried with anhydrous MgSO4, filtered, and most of the low-boiling solvent was removed by vacuum extraction. The fraction at 68℃ / 24mmHg was collected to obtain n-BuC5H5.

[0045] (2) Preparation of 6,6-dimethyl-2-butylfulene: Under inert gas protection, n-BuC5H5 and acetone were added to the reaction flask, and pyrrolidine was slowly added dropwise at -20 to 0℃. The reaction was stirred for 24 h. Ice water was added, and the pH was adjusted to neutral with acetic acid. The organic phase was collected by separation, and the aqueous phase was extracted with diethyl ether. The organic phases were combined, washed with saturated NaCl aqueous solution, dried with anhydrous MgSO4, filtered, concentrated, and separated by column chromatography with petroleum ether-ethyl acetate (volume ratio 3:1) as the mobile phase. After concentration, 6,6-dimethyl-2-butylfulene was obtained.

[0046] The present invention also provides a metallocene catalyst composition, which is prepared by the above-described method for preparing the metallocene catalyst composition.

[0047] According to a specific embodiment of the present invention, preferably, its composition comprises a carbon-bridged metallocene compound and a substituted dimetallocene compound in a molar ratio of 10:1.25-1.5;

[0048] The structure of the carbon-bridged metallocene compound is shown in Formula I:

[0049] [RC(CH3)2(n-BuCp)]MCl2 Equation I,

[0050] In Formula I, R is selected from C3-C6 amino groups (more preferably from aromatic hydrocarbon amino groups, cycloalkane amino groups, aliphatic hydrocarbon amino groups, such as aniline, cyclohexylamino, tert-butylamino), Cp is cyclopentadienyl and its derivatives, and M is Ti or Zr;

[0051] The structure of the substituted metallocene compound is shown in Formula II:

[0052] [CH2=C(CH3)(n-BuCp)]2MCl2 Equation II,

[0053] In Formula II, Cp represents cyclopentadienyl and its derivatives, and M represents Ti or Zr.

[0054] The present invention also provides a metallocene catalytic system comprising the above-mentioned metallocene catalyst composition and a cocatalyst; wherein the cocatalyst is an organoaluminum and / or boron compound.

[0055] The present invention also provides a method for olefin polymerization, which uses the above-mentioned metallocene catalytic system for catalytic reaction, comprising the following steps: adding solvent, olefin feedstock, the metallocene catalyst composition and co-catalyst to a reaction vessel, and carrying out olefin polymerization reaction at 40°C to 120°C, more preferably at 60°C to 100°C.

[0056] According to a specific embodiment of the present invention, preferably, the olefin polymerization includes ethylene polymerization, ethylene-α-olefin polymerization, or α-olefin polymerization.

[0057] According to a specific embodiment of the present invention, preferably, when the metallocene catalytic system (with MAO as a cocatalyst) is used to catalyze the copolymerization of ethylene and 1-octene, the catalytic activity of the metallocene catalyst composition is ≥1.1 × 10⁻⁶. 6 gPE / (mol·M·h).

[0058] The present invention also provides a polyolefin obtained by the above-described olefin polymerization method.

[0059] According to a specific embodiment of the present invention, preferably, when the polyolefin is a copolymer of ethylene and 1-octene, the polymer obtained by catalysis is subjected to... 13 The 1-octene insertion rate of the polyolefin was determined by C NMR to be ≥5.2% mol.

[0060] According to a specific embodiment of the present invention, preferably, when the polyolefin is a 1-decene polymerization product (MAO can be selected as the co-catalyst), the kinematic viscosity KV of the polymerization product at 100°C is 3.15-3.40 cSt, and the viscosity index KI is 129-136.

[0061] This invention enables the one-pot synthesis of metallocene catalyst compositions by controlling reaction conditions, simplifying the synthesis steps, shortening the synthesis route, reducing losses caused by intermediate product separation, and improving the yield. This invention has the following beneficial effects:

[0062] 1. Two types of metallocene compounds are simultaneously synthesized in a one-pot process by controlling reaction conditions. The ratio of the two metallocene compounds in the final product can be adjusted by modifying the proportion of raw materials added during the synthesis process. The two metallocene compounds in the metallocene catalyst composition have the same cyclopentadiene structure. Before metal coordination, the amount of alkylamine added is adjusted to amination of a portion of the cyclopentadiene derivative, thereby achieving the simultaneous synthesis of two metallocene ligands. Finally, after metal coordination, these two types of metallocene compounds are obtained.

[0063] 2. The metallocene catalyst composition of the present invention, through the design of metallocene ligands, achieves the regulation of the metallocene structural space and steric hindrance effect during the catalytic polymerization process, thereby achieving good catalytic polymerization ability. It can catalyze ethylene polymerization, ethylene-α-olefin polymerization, α-olefin polymerization, realize highly active polymerization of ethylene-α-olefin, and prepare low viscosity mPAO, etc. Detailed Implementation

[0064] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0065] Example 1

[0066] This embodiment provides a metallocene catalyst composition C1, which is prepared by the following steps:

[0067] (1) Synthesis of 6,6-dimethyl-2-butylfulene

[0068] A 250 mL three-necked flask was equipped with a magnetic stirrer and a constant-pressure dropping funnel, and evacuated and purged with argon three times. Under argon protection, 100 mL of 0.178 mol CpNa THF solution was added to the reaction flask, and the mixture was stirred and cooled at -10 °C. Under argon protection, 0.167 mol n-BuBr was added to the constant-pressure dropping funnel slowly. The solution turned gray and a large amount of precipitate was formed. After the addition was complete, the reaction solution was a turbid substance containing a large amount of grayish-white precipitate. The reaction was stirred for 12 h. After standing, a grayish-white precipitate was found at the bottom of the flask, and the upper liquid was yellow. 20 mL of ice water was added and stirred. The precipitate dissolved completely and the layers separated. The organic phase was separated and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with 30 mL of saturated NaCl aqueous solution and 10 mL of H2O. The mixture was dried over anhydrous MgSO4 for 6 h, filtered, and most of the low-boiling solvent was removed under vacuum. The fraction at 68 °C / 24 mmHg was collected to obtain 8.9 g of pale yellow liquid, which was identified by NMR as the target product n-BuC5H5, with a yield of 43.5%. 1HNMR (δ, ppm, CDCl3, 400MHz): 6.18-6.50 (m, 4.09H, Cp-H), 2.91 (s, 1.00H, Cp-H), 0.96 (m, 2.96H, Bu-H), 1.29-1.333 (m, 5.89H, Bu-H).

[0069] Under argon protection, 41 mmol n-BuC5H5 and 82 mmol acetone were added to a 100 mL Schlenk flask. The mixture was stirred and cooled at -5 °C, and 61.5 mmol pyrrolidine was slowly added dropwise. The reaction solution turned pale yellow and then red. The reaction was stirred for 24 h. 4 mL of ice water was added, and the pH was adjusted to neutral with acetic acid. The mixture was separated, and the organic phase was collected. The aqueous phase was extracted with diethyl ether. The organic phases were combined, washed with 30 mL of saturated NaCl aqueous solution, dried over anhydrous MgSO4, filtered, and the solvent was concentrated. The mixture was separated by column chromatography using petroleum ether-ethyl acetate (3:1) as the mobile phase. After concentration, 3.7 g of red liquid was obtained, which was identified by NMR as the target product 6,6-dimethyl-2-butylfulne, with a yield of 56%. 1 HNMR (δ, ppm, CDCl3, 400MHz): 6.18-6.50 (m, 3.02H, Cp-H), 2.88 (s, 0.97H, Cp-H), 1.01 (m, 5.96H, C H3-H), 1.96 (d, 1.99H, CH2-H), 1.90 (s, 0.99H, CH-H), 0.96 (m, 2.99H, Bu-H), 1.33 (m, 3.99H, Bu-H).

[0070] (2) Synthesis of metallocene catalyst composition C1

[0071] Under argon protection, 5.5 mmol of n-BuLi was added to a 50 mL Schlenk flask, cooled to -20 °C, and 5 mmol of aniline was slowly added dropwise with stirring. After the addition was complete, the reaction was allowed to proceed for 24 hours. The solvent was removed under vacuum, yielding a white solid. Then, 20 mL of n-hexane and 5 mL of THF were added at -20 °C, and the mixture was stirred to dissolve. Under argon protection, 5 mmol of 6,6-dimethyl-2-butylfuran was added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then raised to 25 °C, and the reaction was stirred for 48 hours. Another 5.5 mmol of n-BuLi was added, and the reaction was continued with stirring for 48 hours. The solvent was removed under vacuum, and 20 mL of n-hexane and 5 mL of tetrahydrofuran were added. Under argon protection, 5 mmol of aniline was slowly added at -78 °C. TiCl4·2THF was reacted at -78℃ for 2 h; then the temperature was naturally raised to room temperature (25℃) and the reaction was continued for 24 h; the solvent was removed under vacuum, hexane was added for washing, the mixture was filtered, and the solid precipitate was dried to obtain a brownish-red solid powder. After recrystallization with dichloromethane-hexane at a volume ratio of 2:1, 1.199 g of brownish-red crystals, i.e., the metallocene catalyst composition, was obtained, with a yield of 64.7%.

[0072] through 1 H NMR and MS tests showed that the metallocene catalyst composition C1 is a mixture of metallocenes, wherein the carbon-bridged metallocene compound has the molecular structure: [C6H5NC(CH3)2(n-BuC5H3)]TiCl2, and the substituted dimetallocene compound has the molecular structure: [CH2=C(CH3)(n-BuC5H3)]2TiCl2, with a molar ratio of 10:1.34. The NMR results for the composition are as follows: 1 HNMR (δ, ppm, CDCl3, 400MHz): 7.29~7.01 (m, 4.85H, Ph-H), 6.13-6.49 (m, 3.18H, Cp-H), 5.40 (s, 0.26H, = CH2), 5.2 4(s,0.22H,=CH2),2.04(s,0.66H,CH3),1.28(s,6H,C(CH3)2),0.96(s,2.99H,Bu-H),1.33-1.96(m,5.89H,Bu-H).

[0073] Example 2

[0074] This embodiment provides a metallocene catalyst composition C2, which is prepared by the following steps:

[0075] (1) Synthesis of 6,6-dimethyl-2-butylfulene

[0076] Same as Example 1;

[0077] (2) Synthesis of metallocene catalyst composition C2

[0078] Under argon protection, 5.5 mmol of n-BuLi was added to a 50 mL Schlenk flask, cooled to -10 °C, and 5 mmol of cyclohexylamine was slowly added dropwise with stirring. After the addition was complete, the reaction was carried out for 36 hours. The solvent was removed under vacuum, yielding a white solid. Then, 20 mL of n-hexane and 5 mL of THF were added at -20 °C and stirred to dissolve. Under argon protection, 5 mmol of 6,6-dimethyl-2-butylfulne was added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then raised to 25 °C, and the reaction was stirred for 48 hours. 5.5 mmol of n-BuLi was added again, and the reaction was stirred for another 48 hours. The solvent was removed under vacuum, and 20 mL of n-hexane and 5 mL of tetrahydrofuran were added. Under argon protection, 5 mmol of cyclohexane was slowly added at -78 °C. The reaction was carried out at -78°C for 2 hours using ZrCl4·2THF, and then allowed to rise naturally to room temperature for 24 hours. The solvent was removed under vacuum, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a solid powder. After recrystallization with dichloromethane-n-hexane at a volume ratio of 2:1, 1.388 g of crystals, i.e., the metallocene catalyst composition, was obtained with a yield of 56.3%.

[0079] through 1 ¹H NMR and MS tests showed that the metallocene catalyst composition C2 is a metallocene mixture, wherein the molecular structure of the carbon-bridged metallocene compound is: [C6H 11 The substituted metallocene compound NC(CH3)2(n-BuC5H3)]ZrCl2 has the molecular structure [CH2=C(CH3)(n-BuC5H3)]2ZrCl2, with a molar ratio of 10:1.29. The NMR results for the composition are as follows: 1 HNMR (δ, ppm, CDCl3, 400MHz): 6.57~6.33 (m, 3.12H, Cp-H), 5.40 (s, 1.01H, C= CH2),1.68(s,1.56H,CH3),1.42(s,6H,C(CH3)2),1.22-1.01(m,11.07H,C6H 11 ),0.96(s,2.99H,Bu-H),1.33-1.96(m,6.05H,Bu-H).

[0080] Example 3

[0081] This embodiment provides a metallocene catalyst composition C3, which is prepared by the following steps:

[0082] (1) Synthesis of 6,6-dimethyl-2-butylfulene

[0083] A 250 mL three-necked flask was equipped with a magnetic stirrer and a constant-pressure dropping funnel, and evacuated and purged with argon three times. Under argon protection, 100 mL of 0.180 mol CpNa THF solution was added to the reaction flask, and the mixture was stirred and cooled at -10 °C. Under argon protection, 0.170 mol n-BuBr was added to the constant-pressure dropping funnel slowly. The solution turned gray and a large amount of precipitate was formed. After the addition was complete, the reaction solution was a turbid substance containing a grayish-white precipitate. The reaction was stirred for 24 h. After standing, a grayish-white precipitate was found at the bottom of the bottle, and the upper liquid was yellow. 10 mL of ice water was added and stirred. The precipitate dissolved completely and the layers separated. The organic phase was separated and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with 10 mL of saturated NaCl aqueous solution and 10 mL of H2O. The mixture was dried over anhydrous MgSO4 for 6 h, filtered, and most of the low-boiling solvent was removed under vacuum. The fraction at 68 °C / 24 mmHg was collected to obtain 9.60 g of pale yellow liquid, which was identified by NMR as the target product n-BuC5H5, with a yield of 46.1%.

[0084] Under argon protection, 41 mmol n-BuC5H5 and 82 mmol acetone were added to a 100 mL Schlenk flask. The mixture was stirred and cooled at -10 °C, and 61 mmol pyrrolidine was slowly added dropwise. The reaction solution turned pale yellow, then red, and the reaction was stirred for 24 h. 4 mL of ice water was added, and the pH was adjusted to neutral with acetic acid. The mixture was separated, and the organic phase was collected. The aqueous phase was extracted with diethyl ether. The combined organic phases were washed with 20 mL of saturated NaCl aqueous solution, dried over anhydrous MgSO4, filtered, and the solvent was concentrated. The mixture was separated by column chromatography using petroleum ether-ethyl acetate (3:1) as the mobile phase. After concentration, 3.87 g of red liquid was obtained, which was identified by NMR as the target product 6,6-dimethyl-2-butylene, with a yield of 58.5%.

[0085] (2) Synthesis of metallocene catalyst composition C3

[0086] Under argon protection, 5.5 mmol of n-BuLi was added to a 50 mL Schlenk flask, cooled to -10 °C, and 5 mmol of aniline was slowly added dropwise with stirring. After the addition was complete, the reaction was allowed to proceed for 24 hours. The solvent was removed under vacuum, yielding a white solid. Then, 20 mL of n-hexane and 5 mL of THF were added at -20 °C, and the mixture was stirred to dissolve. Under argon protection, 5 mmol of 6,6-dimethyl-2-butylfuran was added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then raised to 25 °C, and the reaction was stirred for 48 hours. Another 5.5 mmol of n-BuLi was added, and the reaction was continued with stirring for another 48 hours. The solvent was removed under vacuum, and 20 mL of n-hexane and 5 mL of tetrahydrofuran were added. Under argon protection, 5 mmol of aniline was slowly added at -78 °C. The reaction was carried out at -78°C for 2 hours using ZrCl4·2THF, and then allowed to rise naturally to room temperature for 24 hours. The solvent was removed under vacuum, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a solid powder. After recrystallization with dichloromethane-n-hexane at a volume ratio of 2:1, 1.329 g of crystals, i.e., the metallocene catalyst composition, was obtained with a yield of 53.9%.

[0087] through 1 H NMR and MS tests showed that the metallocene catalyst composition C3 is a mixture of metallocenes, wherein the carbon-bridged metallocene compound has the molecular structure: [C6H5NC(CH3)2(n-BuC5H3)]ZrCl2, and the substituted dimetallocene compound has the molecular structure: [CH2=C(CH3)(n-BuC5H3)]2ZrCl2, with a molar ratio of 10:1.32. The NMR results of the composition are as follows: 1 HNMR (δ, ppm, CDCl3, 400MHz): 7.29~7.01 (m, 5.05H, Ph-H), 6.31-6.49 (m, 4.28H, Cp-H), 5.40 (s, 0.26H, = CH2), 5.2 4(s,0.22H,=CH2),2.04(s,0.66H,CH3),1.60(s,6H,C(CH3)2),0.96(s,2.99H,Bu-H),1.33-1.88(m,5.89H,Bu-H).

[0088] Example 4

[0089] This embodiment provides a metallocene catalyst composition C4, which is prepared by the following steps:

[0090] (1) Synthesis of 6,6-dimethyl-2-butylfulene

[0091] Same as Example 3;

[0092] (2) Synthesis of metallocene catalyst composition C4

[0093] Under argon protection, 5.5 mmol of n-BuLi was added to a 50 mL Schlenk flask, cooled to -20 °C, and 5 mmol of tert-butylamine was slowly added dropwise with stirring. After the addition was complete, the reaction was allowed to proceed for 24 hours. The solvent was removed under vacuum, yielding a white solid. Then, 20 mL of n-hexane and 5 mL of THF were added at -10 °C, and the mixture was stirred to dissolve. Under argon protection, 5 mmol of 6,6-dimethyl-2-butylfuran was added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then raised to 25 °C, and the reaction was stirred for 24 hours. Another 5.5 mmol of n-BuLi was added, and the reaction was continued with stirring for 48 hours. The solvent was removed under vacuum, and 20 mL of n-hexane and 5 mL of tetrahydrofuran were added. Under argon protection, 5 mmol of tert-butylamine was slowly added at -78 °C. The reaction was carried out at -78°C for 2 hours using ZrCl4·2THF. Then the temperature was raised to 25°C and the reaction was carried out for 24 hours. The solvent was removed under vacuum, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a solid powder. After recrystallization with dichloromethane-n-hexane at a volume ratio of 2:1, 1.200 g of crystals, i.e., the metallocene catalyst composition, was obtained with a yield of 60.1%.

[0094] through 1 H NMR and MS tests showed that the metallocene catalyst composition C4 is a metallocene mixture, wherein the carbon-bridged metallocene compound has the molecular structure: [t-C4H9NC(CH3)2(n-BuC5H3)]ZrCl2, and the substituted dimetallocene compound has the molecular structure: [CH2=C(CH3)(n-BuC5H3)]2ZrCl2, with a molar ratio of 10:1.40. The NMR results of the composition are as follows: 1 HNMR (δ, ppm, CDCl3, 400MHz): 6.18-6.48 (m, 3.09H, Cp-H), 1.25 (s, 5.92H, (CH3)2). 5.40 (s, 0.26H, = CH2), 5.24 (s, 0.22H, = CH2), 2.04 (s, 0.66H, CH3), 0.96 (s, 3.09H, Bu-H), 1.33-1.96 (m, 5.99H, Bu-H).

[0095] Test Example 1: C1 Catalysis of Ethylene-1-Octene Copolymerization Using a Metallocene Catalyst Composition

[0096] Before the reaction, the reactor was preheated under vacuum, and then rinsed three times with argon gas. The temperature was then maintained at 80°C. The following materials were added in a glove box: 10 μmol of metallocene catalyst composition C1 (based on the total molar amount of the metallocene catalyst composition), 100 mL of toluene, 10 mL of MAO, and 25 mL of 1-octene. After adding the materials through the feeder, the ethylene pressure was set to 0.8 MPa. After reacting for 30 minutes, the ethylene inlet valve was closed, and hydrochloric acid-ethanol solution was added to terminate the reaction. The mixture was cooled by turning on the cooling water, and the product was removed. It was repeatedly rinsed with hydrochloric acid-ethanol solution to dissolve the reaction residue, and then washed three more times with deionized water. Finally, it was placed in a vacuum drying oven and dried at 60°C to constant weight, yielding 5.42 g of polymer solid. The activity of the metallocene catalyst composition C1 was calculated to be 1.08 × 10⁻⁶. 6 g / (mol·Ti h), based on the polymer 13 The 1-octene insertion rate in the copolymer was calculated to be 7.45% based on the C-NMR spectrum.

[0097] Test Example 2: C2-catalyzed copolymerization of ethylene and 1-octene using a metallocene catalyst composition

[0098] Before the reaction, the reactor was preheated under vacuum, and then rinsed three times with argon gas. The temperature was then maintained at 90°C. The following materials were added in a glove box: 10 μmol of metallocene catalyst composition C2 (based on the total molar amount of the metallocene catalyst composition), 100 mL of toluene, 10 mL of MAO, and 25 mL of 1-octene. After adding the materials through the feeder, the ethylene pressure was set to 0.8 MPa. After reacting for 30 minutes, the ethylene inlet valve was closed, and hydrochloric acid-ethanol solution was added to terminate the reaction. The mixture was cooled by turning on the cooling water, and the product was removed. It was repeatedly rinsed with hydrochloric acid-ethanol solution to dissolve the reaction residue, then rinsed three more times with deionized water. Finally, it was placed in a vacuum drying oven and dried at 60°C to constant weight, yielding 6.75 g of polymer solid. The activity of the metallocene catalyst composition C2 was calculated to be 1.35 × 10⁻⁶. 6 g / (mol·Zr·h), based on the polymer 13 C-NMR spectroscopy calculations showed that the 1-octene insertion rate in the copolymer was 5.2%.

[0099] Test Example 3: C3-catalyzed oligomerization of 1-decene using a metallocene catalyst composition

[0100] The three-necked flask was dried and purged three times with argon gas. 100 mL of 1-decene was added to the flask, followed by 5.0 mL of MAO and 5.0 mg of the metallocene catalyst composition C3 (dissolved in 5 mL of toluene 30 min prior). The mixture was heated to 60 °C and reacted for 8 h. After the reaction was complete, 30 mL of hydrochloric acid-ethanol was added to terminate the reaction. Ethanol was removed by atmospheric distillation, and toluene and monomer were removed by vacuum distillation, yielding the 1-decene oligomer. The monomer conversion was calculated to be 77.2%. The KV of the obtained 1-decene oligomer was 13.35 cSt at 40 °C, 3.42 cSt at 100 °C, and the viscosity index VI was 136.

[0101] Test Example 4: C4 Catalytic Oligomerization of 1-Decanene Catalyzed by Metallocene Catalyst Composition

[0102] The three-necked flask was dried and purged three times with argon gas. 100 mL of 1-decene was added to the flask, followed by 5.0 mL of MAO and 5.0 mg of the metallocene catalyst composition C4 (dissolved in 5 mL of toluene 30 min prior). The mixture was heated to 60 °C and reacted for 8 h. After the reaction was complete, 30 mL of hydrochloric acid-ethanol was added to terminate the reaction. Ethanol was removed by atmospheric distillation, and toluene and monomer were removed by vacuum distillation, yielding the 1-decene oligomer. The monomer conversion was calculated to be 81.4%, and the KV of the obtained 1-decene oligomer was 12.35 cSt at 40 °C, 3.21 cSt at 100 °C, and the viscosity index VI was 129.

[0103] Test Example 5: C2-catalyzed oligomerization of 1-decene using a metallocene catalyst composition

[0104] The three-necked flask was dried and purged three times with argon gas. 100 mL of 1-decene was added to the flask, followed by 5.0 mL of MAO and 5.0 mg of a metallocene catalyst composition C2 (dissolved in 5 mL of toluene 30 min prior). The mixture was heated to 80 °C and reacted for 8 h. After the reaction was complete, 30 mL of hydrochloric acid-ethanol was added to terminate the reaction. Ethanol was removed by atmospheric distillation, and toluene and monomer were removed by vacuum distillation, yielding the 1-decene oligomer. The monomer conversion was calculated to be 78.8%, and the KV of the obtained 1-decene oligomer was 11.83 cSt at 40 °C, 3.15 cSt at 100 °C, and the viscosity index VI was 133.

[0105] Comparative Example 1

[0106] This comparative example provides a metallocene catalyst composition C5, which is prepared by the following steps:

[0107] (1) The synthesis of 6,6-dimethyl-2-butylfulne was the same as in Example 1;

[0108] (2) Synthesis of metallocene catalyst composition C5, by changing the reaction temperature of amine lithium with olefins to -40℃:

[0109] Under argon protection, 5.5 mmol n-BuLi was added to a 50 mL Schlenk flask, cooled to -20 °C, and 5 mmol aniline was slowly added dropwise with stirring. After the addition was complete, the reaction was carried out for 24 hours. The solvent was removed under vacuum to obtain a white solid. Then, 20 mL n-hexane and 5 mL THF were added at -20 °C and stirred to dissolve. Under argon protection, 5 mmol 6,6-dimethyl-2-butylfulne was added at -40 °C, and the reaction was maintained at -40 °C for 2 hours. Then, the temperature was raised to 25 °C and the reaction was stirred for 48 hours. The rest of the reaction was the same as in Example 1.

[0110] The solvent was removed by vacuum extraction, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a brownish-red solid powder. After recrystallization with dichloromethane-n-hexane at a volume ratio of 2:1, 0.6523 g of brownish-red crystals, i.e., the metallocene catalyst composition, was obtained, with a yield of 34.6%.

[0111] Comparative Example 2

[0112] This comparative example provides a metallocene catalyst composition C6, which is prepared by the following steps:

[0113] (1) The synthesis of 6,6-dimethyl-2-butylfulne was the same as in Example 1;

[0114] (2) Synthesis of metallocene catalyst composition C6, by changing the complexation reaction temperature of the double lithium salt with TiCl4·2THF to -40℃:

[0115] Under argon protection, 5.5 mmol n-BuLi was added to a 50 mL Schlenk flask, cooled to -20 °C, and 5 mmol aniline was slowly added dropwise with stirring. After the addition was complete, the reaction was carried out for 24 hours. The solvent was removed under vacuum to obtain a white solid. Then, 20 mL n-hexane and 5 mL THF were added at -20 °C and stirred to dissolve. Under argon protection, 5 mmol 6,6-dimethyl-2-butylfulne was added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. Then, the temperature was raised to 25 °C, and the reaction was stirred for 48 hours. Then, 5.5 mmol n-BuLi was added, and the reaction was stirred for another 48 hours. The solvent was removed under vacuum, and 20 mL n-hexane and 5 mL tetrahydrofuran were added. Under argon protection, 5 mmol TiCl4·2THF was slowly added at -40 °C, and the reaction was maintained at -40 °C for 2 hours. Then, the temperature was naturally raised to room temperature (25 °C), and the reaction was carried out for 24 hours. The rest of the reaction was the same as in Example 1.

[0116] The solvent was removed by vacuum extraction, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a brownish-red solid powder. After recrystallization with dichloromethane-n-hexane in a volume ratio of 2:1, 0.5244 g of brownish-red crystals, i.e., the metallocene catalyst composition, was obtained, with a yield of 28.3%.

[0117] Comparative Example 3

[0118] This comparative example provides a metallocene catalyst composition C7, which is prepared by the following steps:

[0119] (1) The synthesis of 6,6-dimethyl-2-butylfulne was the same as in Example 1;

[0120] (2) Synthesis of metallocene catalyst composition C7: The solvent for the complexation reaction of the double lithium salt with TiCl4·2THF was changed to a volume ratio of hexane and tetrahydrofuran of 1:1.

[0121] Under argon protection, 5.5 mmol n-BuLi was added to a 50 mL Schlenk flask, cooled to -20 °C, and 5 mmol aniline was slowly added dropwise with stirring. After the addition was complete, the reaction was allowed to proceed for 24 hours. The solvent was removed under vacuum, yielding a white solid. Then, 20 mL n-hexane and 5 mL THF were added at -20 °C and stirred to dissolve. Under argon protection, 5 mmol 6,6-dimethyl-2-butylfulne was added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then raised to 25 °C, and the reaction was stirred for 48 hours. Another 5.5 mmol n-BuLi was added, and the reaction was continued with stirring for 48 hours. The solvent was removed under vacuum, and 12.5 mL n-hexane and 12.5 mL tetrahydrofuran were added. Under argon protection, 5 mmol TiCl4·2THF was slowly added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then allowed to rise naturally to room temperature (25 °C), and the reaction was allowed to proceed for 24 hours.

[0122] The solvent was removed by vacuum extraction, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a brownish-red solid powder. After recrystallization with dichloromethane-n-hexane in a volume ratio of 2:1, 0.9006 g of brownish-red crystals, i.e., the metallocene catalyst composition, was obtained with a yield of 48.60%.

[0123] Comparative Example 4

[0124] This comparative example provides a metallocene catalyst composition C8, which is prepared by the following steps:

[0125] (1) The synthesis of 6,6-dimethyl-2-butylfulne was the same as in Example 1;

[0126] (2) Synthesis of metallocene catalyst composition C8: The reaction time of the amine lithium 6,6-dimethyl-2-butyl-richene complexation was changed to -78℃ for 1 hour and then stirred at 25℃ for 12 hours.

[0127] Under argon protection, 5.5 mmol of n-BuLi was added to a 50 mL Schlenk flask, cooled to -20 °C, and 5 mmol of aniline was slowly added dropwise with stirring. After the addition was complete, the reaction was allowed to proceed for 24 hours. The solvent was removed under vacuum, yielding a white solid. Then, 20 mL of n-hexane and 5 mL of THF were added at -20 °C and stirred to dissolve. Under argon protection, 5 mmol of 6,6-dimethyl-2-butylfulne was added at -78 °C, and the reaction was maintained at -78 °C for 1 hour. The temperature was then raised to 25 °C, and the reaction was stirred for 12 hours. 5.5 mmol of n-BuLi was added again, and the reaction was continued with stirring for 48 hours. The solvent was removed under vacuum, and 20 mL of n-hexane and 5 mL of tetrahydrofuran were added. Under argon protection, 5 mmol of TiCl4·2THF was slowly added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then allowed to rise naturally to room temperature (25 °C), and the reaction was allowed to proceed for 24 hours.

[0128] The solvent was removed by vacuum extraction, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a brownish-red solid powder. After recrystallization with dichloromethane-n-hexane in a volume ratio of 2:1, 0.4739 g of brownish-red crystals, i.e., the metallocene catalyst composition, was obtained, with a yield of 26.1%.

[0129] Comparative Example 5

[0130] This comparative example provides a metallocene catalyst composition C9, which is prepared by the following steps:

[0131] (1) The synthesis of 6,6-dimethyl-2-butylfulne was the same as in Example 1;

[0132] (2) Synthesis of the metallocene catalyst composition C9, by changing the molar ratio of n-BuLi to ZrCl4·2THF to 1:1.2:

[0133] Under argon protection, 5.5 mmol of n-BuLi was added to a 50 mL Schlenk flask, cooled to -10 °C, and 5 mmol of cyclohexylamine was slowly added dropwise with stirring. The reaction was allowed to proceed for 36 hours after the addition was complete. The solvent was removed under vacuum, yielding a white solid. Then, 20 mL of n-hexane and 5 mL of THF were added at -20 °C, and the mixture was stirred to dissolve. Under argon protection, 5 mmol of 6,6-dimethyl-2-butylfuran was added at -78 °C, and the reaction was maintained at -78 °C for 2 hours. The temperature was then raised to 25 °C, and the reaction was stirred for 48 hours. Another 5.5 mmol of n-BuLi was added, and the reaction was continued with stirring for another 48 hours. The solvent was removed under vacuum, and 20 mL of n-hexane and 5 mL of tetrahydrofuran were added. Under argon protection, 6.6 mmol of cyclohexane was slowly added at -78 °C. The reaction was carried out at -78°C for 2 hours using ZrCl4·2THF. Then, the temperature was naturally raised to room temperature and the reaction was continued for 24 hours. The solvent was removed under vacuum, and the mixture was washed with n-hexane, filtered, and the solid precipitate was dried to obtain a solid powder. After recrystallization with dichloromethane-n-hexane at a volume ratio of 2:1, 1.425 g of crystals, i.e., the metallocene catalyst composition, was obtained with a yield of 43.8%.

[0134] As can be seen from the above, the metallocene catalyst composition of the present invention exhibits a 1-octene insertion rate of over 5.2% mol during the copolymerization of ethylene and 1-octene, and a catalytic activity ≥ 1.1 × 10⁻⁶. 6 gPE / mol M h; In the preparation of low-viscosity PAO by catalytic oligomerization of 1-decene, the kinematic viscosity KV of the obtained polymer product at 100℃ is 3.15-3.40 cSt, and the viscosity index KI is 129-136.

Claims

1. A method for preparing a metallocene catalyst composition, comprising the following steps: (1) Under a protective gas atmosphere, the n-BuLi solution was cooled to -20°C to 0°C, and then an amine compound was added to react and obtain amine lithium; (2) Under conditions of -20℃ to 0℃, the amino lithium obtained in step (1) is mixed with a solvent, and 6,6-dimethyl-2-butylfulne and / or its derivatives are added at -70℃ to -100℃ under a protective gas atmosphere to carry out the reaction. (3) Add n-BuLi to the reaction solution of step (2) to carry out the reaction. After removing the solvent, add the solvent again. Under a protective gas atmosphere, add MCl4·2THF at -70℃ to -90℃ and keep the temperature at -70℃ to -90℃ to carry out the reaction. Raise the temperature to 20℃ to 30℃ to continue the reaction. Remove the solvent, wash, filter and recrystallize to obtain the metallocene catalyst composition.

2. The preparation method according to claim 1, wherein, The reaction in step (2) is to maintain the reaction at -70°C to -100°C and then raise the temperature to 20°C to 30°C to continue the reaction.

3. The preparation method according to claim 2, wherein, The reaction in step (2) is as follows: maintain the temperature at -70℃ to -100℃ for 1-4 hours, then raise the temperature to 20℃ to 30℃ and react for 24-100 hours.

4. The preparation method according to claim 1, wherein, The reaction in step (3) is as follows: maintain the temperature at -70℃ to -90℃ for 1-4 hours, then raise the temperature to 20℃ to 30℃ and react for 24-72 hours.

5. The preparation method according to claim 1, comprising the following steps: (1) Under a protective gas atmosphere, n-BuLi solution was added to the reaction flask, cooled to -20℃ to 0℃, and then an amine compound was added and reacted for 12-48h. The solvent was removed to obtain amine lithium. (2) Under conditions of -20℃ to 0℃, the amino lithium obtained in step (1) is mixed with a solvent, and 6,6-dimethyl-2-butylfulne and / or its derivatives are added at -70℃ to -100℃ under a protective gas atmosphere. The reaction is maintained at -70℃ to -100℃ for 1-4h, and then the temperature is raised to 20℃ to 30℃ for 24-100h. (3) Add n-BuLi to the reaction solution of step (2) and react for 24-48h. After removing the solvent, add the solvent again and add MCl4·2THF at -70℃ to -90℃ under a protective gas atmosphere. Maintain the reaction at -70℃ to -90℃ for 1-4h, then raise the temperature to 20℃ to 30℃ and react for 24-72h. Remove the solvent, wash, filter and recrystallize to obtain the metallocene catalyst composition.

6. The preparation method according to claim 1, wherein, The preparation method includes the following steps: (1) Under a protective gas atmosphere, n-BuLi solution was added to the reaction flask, cooled to -20℃ to -10℃, and then an amine compound was added and reacted for 24-36 h. The solvent was removed to obtain amine lithium. (2) Under conditions of -20℃ to -10℃, the amino lithium obtained in step (1) is mixed with a solvent, and 6,6-dimethyl-2-butylfulne and / or its derivatives are added at -75℃ to -85℃ under a protective gas atmosphere. The reaction is maintained at -75℃ to -85℃ for 2-3 hours, and then the temperature is raised to 20℃ to 30℃ for 24-72 hours. (3) Add n-BuLi to the reaction solution of step (2) and react for 36-48h. After removing the solvent, add the solvent again and add MCl4·2THF at -75℃ to -85℃ under a protective gas atmosphere. Maintain the reaction at -75℃ to -85℃ for 2-3h, then raise the temperature to 20℃ to 30℃ and react for 24-36h. Remove the solvent, wash, filter and recrystallize to obtain the metallocene catalyst composition.

7. The preparation method according to any one of claims 1-6, wherein, In step (1), the molar ratio of n-BuLi to the amine compound is 1:0.8-1.

8. The preparation method according to any one of claims 1-6, wherein, The molar ratio of n-BuLi in step (1) to the molar ratio of 6,6-dimethyl-2-butylfulne and / or its derivatives in step (2) is 1:0.8-1.

9. The preparation method according to any one of claims 1-6, wherein, The solvent used in step (2) is a mixture of n-hexane and tetrahydrofuran in a volume ratio of 3-6:

1.

10. The preparation method according to any one of claims 1-6, wherein, In step (3), the molar ratio of n-BuLi to MCl4·2THF is 1:0.8-1.

11. The preparation method according to any one of claims 1-6, wherein, The molar ratio of n-BuLi added in step (3) to 6,6-dimethyl-2-butylfulne and / or its derivatives in step (2) is 1:0.8-1.

12. The preparation method according to any one of claims 1-6, wherein, The solvent added in step (3) is a mixture of n-hexane and tetrahydrofuran in a volume ratio of 3-6:

1.

13. The preparation method according to any one of claims 1-6, wherein, The amine compound is a C3-C6 amine compound.

14. The preparation method according to any one of claims 1-6, wherein, The metallocene catalyst composition comprises Ti and / or Zr.

15. A metallocene catalyst composition prepared by the preparation method according to any one of claims 1-14.

16. The metallocene catalyst composition according to claim 15, wherein, The metallocene catalyst composition comprises carbon-bridged metallocene compounds and substituted dimetallocene compounds in a molar ratio of 10:1.25-1.

5. The structure of the carbon-bridged metallocene compound is shown in Formula I: [RC(CH3)2(n-BuCp)]MCl2 formula I, In Formula I, R is selected from C3-C6 amino groups, Cp is cyclopentadienyl and its derivatives, and M is Ti or Zr; The structure of the substituted metallocene compound is shown in Formula II: [CH2=C(CH3)(n-BuCp)]2MCl2 Equation II, In Formula II, Cp represents cyclopentadienyl and its derivatives, and M represents Ti or Zr.

17. A metallocene catalytic system comprising the metallocene catalyst composition and cocatalyst as described in claim 15 or 16; The cocatalyst is an organoaluminum and / or boron compound.

18. A method for olefin polymerization, comprising the steps of using the metallocene catalytic system of claim 17 for catalytic reaction: Solvent, olefin feedstock, the metallocene catalyst composition, and co-catalyst are added to the reactor, and the olefin polymerization reaction is carried out at 40°C to 120°C.

19. The method according to claim 18, wherein, The olefin polymerization includes ethylene polymerization, ethylene-α-olefin polymerization, or α-olefin polymerization.

20. The method according to claim 19, wherein, When the metallocene catalytic system is used to catalyze the copolymerization of ethylene and 1-octene, the catalytic activity of the metallocene catalyst composition is ≥1.1×10⁻⁶. 6 gPE / (mol·M·h).

21. A polyolefin prepared by the method of any one of claims 18-20.

22. The polyolefin according to claim 21, wherein, When the polyolefin is a copolymer of ethylene and 1-octene, the 1-octene insertion rate is ≥5.2%mol.

23. The polyolefin according to claim 21, wherein, When the polyolefin is a 1-decene polymer, the kinematic viscosity (KV) of the polyolefin at 100°C is 3.15-3.40 cSt, and the viscosity index (KI) is 129-136.

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