Complex, catalyst composition, preparation method and application thereof, and ethylene oligomerization reaction method

Abstract

The invention provides a complex, a catalyst composition, a preparation method and application and an ethylene oligomerization reaction method, and relates to the technical field of ethylene oligomerization. The structural formula of the complex is shown as a formula (I), in the formula (I), R1-R13 are the same or different and are independently selected from any one of hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitryl and C6-C10 aryl; and R14-R16 are the same or different and are respectively and independently hydrogen or C1-C20 alkyl groups. The complex can be completely dissolved in an organic solvent, the concentration of the complex can be accurately metered in industrial operation, and stable operation of the reaction is ensured. The catalyst composition comprises the complex, so that under the action of the catalyst composition, the ethylene oligomerization reaction is rapid in initiation, stable in operation and good in repeatability.

Description

Complexes, catalyst compositions, their preparation methods and applications, and methods for ethylene oligomerization Technical Field

[0001] This invention relates to the field of ethylene oligomerization technology, and more specifically, to a complex, a catalyst composition, its preparation method and application, and a method for ethylene oligomerization reaction. Background Technology

[0002] Linear α-olefins have wide applications in ethylene comonomers, surfactant synthesis intermediates, plasticizer alcohols, synthetic lubricants, and oil additives. In recent years, with the continuous development of the polyolefin industry, the global demand for α-olefins has grown rapidly. Currently, the vast majority of α-olefins are prepared by ethylene oligomerization. The catalysts used in ethylene oligomerization mainly include nickel-based, chromium-based, zirconium-based, and aluminum-based catalysts. In recent years, Brookhart's group (Brookhart, Me et al., J. Am. Chem. Soc., 1998, 120, 7143-7144; WO99 / 02472, 1999) and Gibson's group (Gibson, VC et al., Chem. Commun., 1998, 849-850; Chem. Eur. J., 2000, 2221-2231) have respectively discovered that some Fe(II) and Co(II) tridentate pyridineimine complexes can catalyze ethylene oligomerization. Not only do these catalysts have high catalytic activity, but they also have high selectivity for α-olefins.

[0003] The research group of Professor Wenhua Sun at the Institute of Chemistry, Chinese Academy of Sciences, reported a catalyst for ethylene oligomerization (Organometallics 2006, 25, 666-677). This catalyst is ferric chloride-2-acetyl-1,10-phenanthroline condensate-2,6-dimethylaniline. With the aid of methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), and a molar ratio of aluminum in the aid catalyst to the central metal in the main catalyst of 1000, the oligomerization and polymerization activities reached a maximum of 3.9 × 10⁻⁶ at 40 °C. 7 g·mol(Fe) -1 ·h -1 However, in actual industrial operation, the main catalyst cannot be well dissolved in the solvent, the concentration of the main catalyst solution cannot be accurately measured, and the catalyst feed rate cannot be stably controlled, resulting in reaction fluctuations and unstable operation. This poses significant safety hazards and causes large fluctuations in product quality. Summary of the Invention

[0004] To address the technical problem in existing technologies where the main catalyst solution cannot dissolve well in the solvent and its concentration cannot be accurately measured, leading to large fluctuations in the ethylene oligomerization reaction and unstable operation, one of the objectives of this invention is to provide a complex that can be completely dissolved in an organic solvent. In industrial operation, the concentration of this complex can be accurately measured to ensure stable reaction operation.

[0005] The second objective of this invention is to provide a method for preparing a complex, the complex obtained by which can be completely dissolved in an organic solvent, so that the concentration of the complex can be accurately measured in industrial operation, thereby ensuring stable reaction operation; and the preparation method has simple synthesis steps and good reproducibility.

[0006] A third objective of this invention is to provide a catalyst composition comprising the aforementioned complex, wherein the ethylene oligomerization reaction is rapidly initiated, runs smoothly, and exhibits good repeatability under the action of this catalyst composition.

[0007] The fourth objective of this invention is to provide an application of the above-mentioned complex or the complex prepared by the above-mentioned preparation method or the above-mentioned catalyst composition in the field of ethylene oligomerization.

[0008] The fifth objective of this invention is to provide a method for ethylene oligomerization.

[0009] To achieve one of the above objectives, the present invention provides a coordination compound with the structural formula shown in formula (I).

[0010]

[0011] In equation (I), R1-R 13 Whether identical or different, each is independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and C6-C 10 Any of the aryl groups; R 14 -R 16 Whether they are the same or different, each is independently hydrogen or C1-C 20 Alkyl group; M is selected from any one of Fe, Co, and Ni, with Fe being preferred.

[0012] Specifically, the complex provided by this invention has excellent solubility after being substituted with acetylacetone groups, and can be completely dissolved in organic solvents. Therefore, the concentration of the complex can be accurately measured in industrial operation, thereby ensuring stable reaction operation.

[0013] In some preferred embodiments of the present invention, in formula (I), R1-R 13Same or different, each independently selected from any one of hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro; and / or, R 14 -R 16 Whether the two are the same or different, each is independently selected from hydrogen or C1-C. 10 alkyl.

[0014] In some preferred embodiments of the present invention, R 14 -R 16 They may be the same or different, and are each independently selected from any one of hydrogen, methyl, ethyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-heptyl, and isoheptyl.

[0015] In some preferred embodiments of the present invention, R1-R7 are hydrogen, R8 is methyl, and R9 and R 13 For methyl, R 10 -R 12 It is hydrogen; R 14 and R 16 For methyl, R 15 It is hydrogen.

[0016] To achieve the second objective mentioned above, the present invention provides a method for preparing a complex, comprising:

[0017] Under an inert gas atmosphere, the compound shown in formula (II) and the compound shown in formula (III) react in an organic solvent to generate a compound with the structural formula shown in formula (I), which is the complex.

[0018]

[0019] R1-R 13 Whether identical or different, each is independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and C6-C 10 Any of the aryl groups; R 14 -R 16 Whether the two are the same or different, each is independently selected from hydrogen or C1-C. 20 Alkyl group; M is selected from any one of Fe, Co, and Ni, with Fe being preferred.

[0020] In some preferred embodiments of the present invention, R1-R 13 Whether identical or different, each is independently selected from any one of hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro; R 14 -R 16 Whether they are the same or different, each is independently hydrogen or C1-C 10 alkyl.

[0021] In some preferred embodiments of the present invention, R 14 -R 16 They may be the same or different, and are each independently selected from any one of hydrogen, methyl, ethyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-heptyl, and isoheptyl.

[0022] In some preferred embodiments of the present invention, R1-R7 are hydrogen, R8 is methyl, and R9 and R 13 For methyl, R 10 -R 12 It is hydrogen; R 14 and R 16 For methyl, R 15 It is hydrogen.

[0023] In some preferred embodiments of the present invention, the molar ratio of the compound represented by formula (III) to the compound represented by formula (II) is (1.0-1.9):1. Within this ratio range, the coordination of the metal with the compounds represented by formula (II) and (III) can be more complete.

[0024] In some preferred embodiments of the present invention, the molar ratio of the compound represented by formula (III) to the compound represented by formula (II) is (1.0-1.6):1.

[0025] In some preferred embodiments of the present invention, the molar ratio of the compound represented by formula (III) to the compound represented by formula (II) is (1.0-1.3):1.

[0026] In some preferred embodiments of the present invention, the inert gas is any one of nitrogen, argon and helium, preferably nitrogen.

[0027] In some preferred embodiments of the present invention, the preparation method includes performing the following steps under an inert gas atmosphere:

[0028] S1. Dissolve the compound shown in formula (II) using an organic solvent to obtain solution A;

[0029] S2. Dissolve the compound shown in formula (III) using an organic solvent to obtain solution B;

[0030] S3. The solution B containing the compound shown in formula (III) is added dropwise to the solution A containing the compound shown in formula (II) to carry out a contact reaction, thereby generating a compound with the structural formula shown in formula (I), which is the complex.

[0031] In some preferred embodiments of the present invention, in step S1, the mass fraction of the compound represented by formula (II) in solution A is 0.1-10 mmol / L, preferably 0.5-5 mmol / L; and / or in step S2, the mass fraction of the compound represented by formula (III) in solution B is 0.1-10 mmol / L, preferably 0.5-5 mmol / L.

[0032] In some preferred embodiments of the present invention, the dropping rate is 0.5-2 mL / min. A dropping rate that is too fast results in a large amount of heat release and makes the reaction difficult to control; a rate that is too slow results in poor reaction efficiency and higher time costs.

[0033] In some preferred embodiments of the present invention, the conditions for the contact reaction include: stirring, preferably at a speed of 100-1000 rpm / min, more preferably at 300-800 rpm / min; and stirring for 0.5-24 h.

[0034] According to the present invention, the stirring time can be determined according to the specific circumstances, and stirring is carried out until the reactants in the solution are completely dissolved.

[0035] In some preferred embodiments of the present invention, the temperature of the contact reaction is 20-30°C. The contact reaction can be carried out at room temperature, i.e., within the range defined above. The dissolution steps S1 and S2 are also carried out at room temperature. If the temperature is too low, the reaction time needs to be extended; if the temperature is too high, the reaction is too vigorous, making the reaction difficult to control.

[0036] In some preferred embodiments of the present invention, the organic solvents in steps S1 and S2 are the same, and the organic solvents are selected from C5-C. 20 Straight-chain alkanes, C3-C 20 Branched alkanes or C3-C 20 Cycloalkanes.

[0037] In some preferred embodiments of the present invention, the organic solvent is selected from any one of n-hexane, cyclohexane, n-heptane, and methylcyclohexane.

[0038] In some preferred embodiments of the present invention, the organic solvent is cyclohexane. Studies have shown that cyclohexane has high reactivity as a solvent and is easily separated from the product; therefore, cyclohexane is preferred as the organic solvent.

[0039] To achieve the third objective mentioned above, the present invention provides a catalyst composition comprising:

[0040] 1) The complexes described above or the complexes prepared by the methods described above;

[0041] 2) Aluminoxane compounds.

[0042] In some preferred embodiments of the present invention, the aluminoxane is a C1-C6 alkylaluminoxane or a modified C1-C6 alkylaluminoxane.

[0043] In some preferred embodiments of the present invention, the C1-C6 alkylaluminoxane includes any one of methylaluminoxane, ethylaluminoxane, and isobutylaluminoxane; and / or, the modified C1-C6 alkylaluminoxane is any one of ethyl-modified methylaluminoxane and butyl-modified methylaluminoxane. When a portion of the methyl group in an alkylaluminoxane is replaced by ethyl or butyl, it is called a modified aluminum oxane (MMAO). Any alkylaluminoxane with different substituent groups is called a modified aluminum oxane.

[0044] In some preferred embodiments of the present invention, the C1-C6 alkylaluminoxane is methylaluminoxane (MAO); and / or, the modified C1-C6 alkylaluminoxane is butyl-modified methylaluminoxane.

[0045] In some preferred embodiments of the present invention, the molar ratio of aluminum in the aluminoxane to M in the complex is (30-900):1. Within this range, complete reaction is desirable.

[0046] In some preferred embodiments of the present invention, the molar ratio of aluminum in the aluminoxane to M in the complex is (100-700):1.

[0047] In some preferred embodiments of the present invention, the molar ratio of aluminum in the aluminoxane to M in the complex is (300-500):1.

[0048] In some preferred embodiments of the present invention, the content of the complex is 0.1-500 μmol / L, calculated based on the total volume of the reaction system consisting of the catalyst composition and the solvent. Within this range, the reaction is more favorable.

[0049] In some preferred embodiments of the present invention, the content of the complex is 0.1-100 μmol / L, calculated based on the total volume of the catalyst composition.

[0050] In some preferred embodiments of the present invention, the content of the complex is 0.5-10 μmol / L, calculated based on the total volume of the catalyst composition.

[0051] To achieve the fourth objective mentioned above, the present invention provides the application of the above-mentioned complex or the complex prepared by the above-mentioned preparation method or the above-mentioned catalyst composition in the ethylene oligomerization reaction.

[0052] In some preferred embodiments of the present invention, the complex is used as the main catalyst for catalyzing the oligomerization reaction of ethylene.

[0053] In some preferred embodiments of the present invention, the conditions for the ethylene oligomerization reaction include: a reaction pressure of 0.1-30 MPa; and / or a reaction temperature of -20-150°C, preferably 10-90°C; and / or a reaction time of 30-100 min.

[0054] In some preferred embodiments of the present invention, the conditions for the ethylene oligomerization reaction include: a reaction temperature of 40-85°C, preferably 45-80°C, and more preferably 50-60°C.

[0055] To achieve the fifth objective mentioned above, the present invention provides a method for ethylene oligomerization, comprising: subjecting ethylene to ethylene oligomerization under the action of the above-mentioned catalyst composition.

[0056] In some preferred embodiments of the present invention, the conditions for the ethylene oligomerization reaction include: a reaction pressure of 0.1-30 MPa; and / or a reaction temperature of -20-150°C, preferably 10-90°C; and / or a reaction time of 30-100 min.

[0057] In some preferred embodiments of the present invention, the conditions for the ethylene oligomerization reaction include: a reaction temperature of 40-85°C, preferably 45-80°C, and more preferably 50-60°C.

[0058] In some preferred embodiments of the present invention, the reaction temperature is 40-60°C. If the reaction temperature is too low, the activity is insufficient, leading to an increase in the amount of catalyst required; if the reaction temperature is too high, it will result in an increase in side reactions.

[0059] The above-mentioned catalyst composition can be applied to the oligomerization reaction of ethylene. Ethylene undergoes oligomerization reaction under the action of the above-mentioned catalyst composition. One specific embodiment may include the following steps: (1) replacing the reaction system by high-temperature drying, vacuum replacement and other operations to ensure that the reaction system is free of water and oxygen; (2) replacing the reaction system with ethylene to make the reaction system in an ethylene environment; (3) adding the catalyst composition to the reaction system and stirring thoroughly; (4) introducing ethylene to start the oligomerization reaction, maintaining the reaction pressure at 0.1-30MPa and the reaction temperature at -20-150℃ for 30-100min; (5) stopping the reaction and taking the reaction product for gas chromatography (GC) analysis.

[0060] During the oligomerization process, the complex and aluminoxane (co-catalyst) are mixed in an ethylene atmosphere. As the ethylene pressure increases, the catalytic activity of the ethylene oligomerization reaction increases.

[0061] Ethylene oligomerization using the catalyst composition described in this invention yields ethylene oligomers including C4, C6, C8, and C6. 10 C 12C 14 C 16 C 18 C 20 C 22 The selectivity for α-olefins can reach over 96%. GC analysis after the ethylene oligomerization reaction was completed showed that the oligomerization activity could reach 3 × 10⁻⁶. 7 g·mol(M) -1 ·h -1 Furthermore, the data showed good repeatability. Additionally, the remaining reaction mixture was neutralized with an ethanol solution acidified with 5% dilute hydrochloric acid, but no polymer was obtained.

[0062] Compared with the prior art, the present invention has at least the following advantages or beneficial effects:

[0063] 1. The present invention provides a complex whose concentration can be accurately measured in industrial operation, ensuring stable reaction operation.

[0064] 2. The present invention provides a method for preparing a complex. The complex prepared by this method has its solubility increased by substituting acetylacetone groups, so that it can be completely dissolved in organic solvents. Therefore, the concentration of the complex can be accurately measured in industrial operation, thereby ensuring stable reaction operation. Moreover, the preparation method has simple synthesis steps and good reproducibility.

[0065] 3. The catalyst composition provided by the present invention contains the above-mentioned complex. Under the action of the catalyst composition, the concentration of the complex solution is uniform, which is conducive to accurate metering. The ethylene oligomerization reaction is initiated rapidly, runs stably, and has good repeatability. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0067] It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0068] Example 1

[0069] (I) Preparation of coordination compounds

[0070] 1) Under nitrogen protection and at room temperature (25℃), 0.325 g of 2-acetyl-1,10-phenanthroline-2,6-dimethylaniline was dissolved in 1 L of cyclohexane (i.e., the concentration of 2-acetyl-1,10-phenanthroline-2,6-dimethylaniline was 1 mmol / L) to obtain solution A;

[0071] 2) Under nitrogen protection and at room temperature, 0.256 g of ferrous acetylacetone was dissolved in 1 L of cyclohexane (i.e., the concentration of ferrous acetylacetone was 1 mmol / L) to obtain solution B;

[0072] 3) Under nitrogen protection and at room temperature, solution B was added dropwise to solution A at a rate of 1 mL / min. The molar ratio of ferrous acetylacetone to 2-acetyl-1,10-phenanthroline-2,6-dimethylaniline was 1.6:1. After the addition was complete, stirring was continued for 30 min (800 rpm / min) to obtain a transparent iron complex solution. The concentration of the soluble iron complex solution, calculated as elemental iron, was 0.5 mmol / L.

[0073] (II) Ethylene oligomerization reaction

[0074] (1) The reactor is replaced by high-temperature drying, vacuum replacement and other operations to ensure that there is no water and no oxygen in the reactor;

[0075] (2) Replace the reactor with ethylene to make the reactor be in an ethylene environment;

[0076] (3) Add 997 mL of cyclohexane and 2 mL of the iron complex solution (complex) prepared in step (I) to the reaction vessel, and then add 1 mL of methylaluminoxane solution (the solubility of methylaluminoxane is 1 mmol / L) to make the total volume of the reaction system 1000 mL. The molar ratio of aluminum in the aluminoxane to Fe in the complex is 500:1 (Al / Fe = 500). After stirring thoroughly, introduce ethylene to start the oligomerization reaction.

[0077] (4) Maintain the ethylene pressure at 1 MPa and the reaction temperature at 50°C for 30 min;

[0078] (5) Stop the reaction, take out a small amount of the reaction product for gas chromatography analysis, and neutralize the remaining mixture with 5% hydrochloric acid-acidified ethanol solution. No polymer was obtained.

[0079] Example 2

[0080] This embodiment is basically the same as that of Embodiment 1, except that in step (i), the molar ratio of ferrous acetylacetone to 2-acetyl-1,10-phenanthroline condensed-2,6-dimethylaniline is 1.3:1.

[0081] Example 3

[0082] This embodiment is basically the same as that of Embodiment 1, except that in step (i), the molar ratio of ferrous acetylacetone to 2-acetyl-1,10-phenanthroline condensed-2,6-dimethylaniline is 1.0:1.

[0083] Example 4

[0084] This embodiment is basically the same as embodiment 3, except that in step (1), ferrous acetylacetone is replaced with ferrous acetylacetone.

[0085] Example 5

[0086] This embodiment is basically the same as embodiment 3, except that in step (1), ferrous acetylacetone is replaced with ferrous acetylenone.

[0087] Example 6

[0088] This embodiment is basically the same as embodiment 3, except that in step (1), ferrous acetylacetone is replaced with ferrous valerate.

[0089] Example 7

[0090] This embodiment is basically the same as embodiment 3, except that in step (ii), the methylaluminoxane solution is replaced with the ethylaluminoxane solution.

[0091] Example 8

[0092] This embodiment is basically the same as embodiment 3, except that in step (ii), the methylaluminoxane solution is replaced with isobutylaluminoxane solution.

[0093] Example 9

[0094] This embodiment is basically the same as embodiment 3, except that in step (ii), the methylaluminoxane solution is replaced with butyl-modified methylaluminoxane (wherein, butyl / (butyl+methyl) is 5%) solution.

[0095] Example 10

[0096] This embodiment is basically the same as embodiment 3, except that in step (ii), Al / Fe = 900.

[0097] Example 11

[0098] This embodiment is basically the same as embodiment 3, except that in step (ii), Al / Fe = 300.

[0099] Example 12

[0100] This embodiment is basically the same as embodiment 3, except that in step (ii), Al / Fe = 100.

[0101] Example 13

[0102] This embodiment is basically the same as embodiment 3, except that in step (ii), the reaction temperature is 60°C.

[0103] Example 14

[0104] This embodiment is basically the same as embodiment 3, except that in step (ii), the reaction temperature is 80°C.

[0105] Test case

[0106] The ethylene oligomerization products from Examples 1-14 were analyzed by gas chromatography, and the results are shown in Table 1.

[0107] Table 1

[0108]

[0109]

[0110] As can be seen from the embodiments of the present invention, the complex provided by the present invention can be completely dissolved in organic solvents. Therefore, the concentration of the complex in the reaction system can be accurately measured, thereby ensuring the stable operation of the reaction and possessing industrial application value.

[0111] As can be seen from the data in Table 1, the catalyst composition provided by this invention has very high oligomerization activity, with catalytic activity generally around 2 × 10⁻⁶. 7 g·mol(Fe) -1 ·h -1 The above can reach up to 3.02×10 7 g·mol(Fe) -1 ·h -1 Therefore, when ethylene undergoes oligomerization in the presence of the catalyst composition provided in this invention, the oligomerization reaction can be rapidly initiated.

[0112] The results of Examples 13 and 14 show that the catalyst composition provided by the present invention maintains high activity as the reaction temperature increases.

[0113] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A complex having the structural formula shown in formula (I), In equation (I), R1-R 13 Whether identical or different, each is independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and C6-C 10 Any of the aryl groups; R 14 -R 16 Whether they are the same or different, each is independently hydrogen or C1-C 20 Alkyl group; M is selected from any one of Fe, Co, and Ni, with Fe being preferred.

2. The complex according to claim 1, characterized in that, In equation (I), R1-R 13 Same or different, each independently selected from any one of hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro; and / or, R 14 -R 16 Whether the two are the same or different, each is independently selected from hydrogen or C1-C. 10 Alkyl group, preferably any one of hydrogen, methyl, ethyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-heptyl, and isoheptyl; preferably, R1-R7 are hydrogen, R8 is methyl, and R9 and R 13 For methyl, R 10 -R 12 It is hydrogen; R 14 and R 16 For methyl, R 15 It is hydrogen.

3. A method for preparing a complex, comprising: Under an inert gas atmosphere, the compound shown in formula (II) and the compound shown in formula (III) react in an organic solvent to generate a compound with the structural formula shown in formula (I), which is the complex. R1-R 13 Whether identical or different, each is independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and C6-C 10 Any of the aryl groups; R 14 -R 16 Whether the two are the same or different, each is independently selected from hydrogen or C1-C. 20 Alkyl group; M is selected from any one of Fe, Co, and Ni, preferably Fe; preferably, R1-R 13 Whether identical or different, each is independently selected from any one of hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro; R 14 -R 16 Whether they are the same or different, each is independently hydrogen or C1-C 10 Alkyl, more preferably, is any one of hydrogen, methyl, ethyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-heptyl, and isoheptyl; preferably, R1-R7 are hydrogen, R8 is methyl, and R9 and R 13 For methyl, R 10 -R 12 It is hydrogen; R 14 and R 16 For methyl, R 15 The inert gas is hydrogen; preferably, the molar ratio of the compound shown in formula (III) to the compound shown in formula (II) is (1.0-1.9):1, more preferably (1.0-1.6):1, and more preferably (1.0-1.3):1; preferably, the inert gas is any one of nitrogen, argon and helium, preferably nitrogen.

4. The preparation method according to claim 3, characterized in that, The preparation method includes the following steps performed under an inert gas atmosphere: S1. Dissolving the compound shown in formula (II) in an organic solvent to obtain solution A; S2. Dissolving the compound shown in formula (III) in an organic solvent to obtain solution B; S3. Adding solution B containing the compound shown in formula (III) dropwise to solution A containing the compound shown in formula (II) to conduct a contact reaction, generating a compound with the structural formula shown in formula (I), which is the complex; preferably, in step S1, the concentration of the compound shown in formula (II) in solution A is 0.1-10 mmol. / L, preferably 0.5-5 mmol / L; and / or in step S2, the concentration of the compound represented by formula (III) in solution B is 0.1-10 mmol / L, preferably 0.5-5 mmol / L; preferably, the dropping rate is 0.5-2 mL / min; preferably, the conditions for the contact reaction include: stirring, preferably, the stirring speed is 100-1000 rpm / min, preferably 300-800 rpm / min; the stirring time is 0.5-24 h; and / or, the temperature is 20-30 °C.

5. The preparation method according to claim 3 or 4, characterized in that, The organic solvent used in steps S1 and S2 is the same, and the organic solvent is selected from C5-C. 20 Straight-chain alkanes, C3-C 20 Branched alkanes or C3-C 20 Cycloalkanes, preferably selected from any one of n-hexane, cyclohexane, n-heptane, and methylcyclohexane, more preferably cyclohexane.

6. A catalyst composition comprising: 1) The complex as described in claim 1 or 2 or the complex prepared by any one of claims 3-5; 2) Aluminoxane compounds, preferably C1-C6 alkylaluminoxanes or modified C1-C6 alkylaluminoxanes.

7. The catalyst composition according to claim 6, characterized in that, The C1-C6 alkylaluminoxane includes any one of methylaluminoxane, ethylaluminoxane, and isobutylaluminoxane, preferably methylaluminoxane; and / or, the modified C1-C6 alkylaluminoxane is any one of ethyl-modified methylaluminoxane and butyl-modified methylaluminoxane, preferably butyl-modified methylaluminoxane.

8. The catalyst composition according to claim 6 or 7, characterized in that, The molar ratio of aluminum in the aluminoxane to M in the complex is (30-900):1, preferably (100-700):1, and more preferably (300-500):

1.

9. The catalyst composition according to any one of claims 6-8, characterized in that, Based on the total volume of the reaction system consisting of the catalyst composition and the solvent, the content of the complex is 0.1-500 μmol / L, preferably 0.1-100 μmol / L, and more preferably 0.5-10 μmol / L.

10. The use of a complex as described in claim 1 or 2, a complex prepared by any one of claims 3-5, or a catalyst composition as described in any one of claims 6-9 in an ethylene oligomerization reaction; preferably, the conditions for the ethylene oligomerization reaction include: The reaction pressure is 0.1-30 MPa; and / or the reaction temperature is -20-150°C, preferably 10-90°C, more preferably 40-85°C, even more preferably 45-80°C, and even more preferably 50-60°C; and / or the reaction time is 30-100 min.

11. A method for ethylene oligomerization, comprising: Ethylene is subjected to an ethylene oligomerization reaction under the action of the catalyst composition according to any one of claims 6-9; preferably, the reaction conditions include: a reaction pressure of 0.1-30 MPa; and / or a reaction temperature of -20-150°C, preferably 10-90°C, more preferably 40-85°C, further preferably 45-80°C, and even more preferably 50-60°C; and / or a reaction time of 30-100 min.

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