Alkenyl bisphosphine bridged catalyst ligands, catalyst compositions and use thereof

Abstract

The application relates to the technical field of ethylene polymerization, and provides an alkenyl diphosphine bridged catalyst ligand, a catalyst composition and application thereof. The structure of the alkenyl diphosphine bridged catalyst ligand is shown in formula (I), wherein R1 and R2 are the same or different and each is independently selected from aryl; R3 is selected from alkyl, cycloalkyl and aryl; R4 and R5 are the same or different and each is independently selected from hydrogen and alkyl; the hydrogen on the carbon of the alkyl, cycloalkyl and aryl is optionally substituted by one or more substituents. The alkenyl diphosphine bridged catalyst ligand provided by the application has a novel structure, is simple to prepare and has low cost; the catalyst composition can effectively catalyze ethylene oligomerization, has high catalytic activity, the reaction is mild and stable, has good repeatability, has high 1-octene selectivity, has good 1-hexene selectivity in C6 products, and has good industrial application prospect and economic value.

Description

Technical Field

[0001] This invention relates to the field of ethylene polymerization technology, and more specifically, to an alkenyl bisphosphine-bridged catalyst ligand, catalyst composition, and its application. Background Technology

[0002] 1-Hexene and 1-Octene are important organic raw materials and chemical intermediates, mainly used in the production of high-quality polyethylene (PE), lubricating oil base oils, plasticizers, and detergents. Among them, linear low-density polyethylene (LLDPE), produced by copolymerizing 1-hexene or 1-octene with ethylene, significantly improves various properties of PE, particularly its mechanical properties, optical properties, tear strength, and impact strength. This product is highly suitable for packaging films and agricultural covering films for greenhouses and sheds. Polyolefin plastomers and polyolefin elastomers produced by copolymerizing 1-octene with ethylene currently have a large market consumption and demand.

[0003] With the continuous development of the polyolefin industry, the global demand for high-carbon-chain α-olefins such as 1-hexene or 1-octene is growing rapidly. High-purity 1-octene, at the copolymerization level, is in short supply in the market, and its price is significantly higher than that of other long-chain α-olefins. Therefore, developing process technologies with higher 1-octene selectivity has significant economic and social value. Furthermore, in existing technologies, the C6 products contain a large number of cyclic olefins and cyclic compounds as byproducts, which is detrimental to the overall economic efficiency of the process.

[0004] Since the 1970s, research on transition metal complex-catalyzed olefin polymerization and oligomerization has gradually gained attention from scientists. Efforts have been made to research new catalysts and improve existing ones, enhancing catalyst activity and the selectivity of catalytic products. For example, Sasol's patent WO2004056478A1 discloses a PNP framework catalyst that, in ethylene tetramerization, exhibits a C8 component selectivity of approximately 66 wt% and a C6 component selectivity of approximately 21 wt%, with a total selectivity of approximately 84% for 1-hexene and 1-octene. US patent 20100137669A1 discloses a PCCP symmetric framework catalyst, which is more stable than the PNP system in ethylene tetramerization, but the total selectivity for 1-hexene and 1-octene does not exceed 85%. There is still room for further improvement in the total selectivity of existing transition metal complex catalysts for 1-hexene and 1-octene.

[0005] Therefore, improving the overall selectivity of 1-hexene and 1-octene in the reaction products, thereby improving the economic efficiency of the process, is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide an alkenyl bisphosphine-bridged catalyst ligand and a catalyst composition to solve the technical problem of low overall selectivity of 1-hexene and 1-octene in ethylene oligomerization products in the prior art.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides an alkenyl bisphosphine-bridged catalyst ligand, the structure of which is shown in formula (I).

[0009]

[0010] In formula (I), R1 and R2 may be the same or different, and each is independently selected from cycloalkyl or aryl; R3 is selected from alkyl, cycloalkyl, or aryl; R4 and R5 may be the same or different, and each is independently selected from hydrogen or alkyl; the hydrogen on the carbon of the alkyl, cycloalkyl, or aryl group may optionally be replaced by one or more substituents.

[0011] According to some embodiments of the present invention, the alkyl group is C1 to C2. 20 Alkyl groups, preferably C1 to C2. 10 Alkyl, more preferably C1 to C6 alkyl.

[0012] According to some embodiments of the present invention, the cycloalkyl group is C3 to C4. 20 Cycloalkyl groups, preferably C3-C4 10 Cycloalkyl, more preferably C3 to C6 cycloalkyl.

[0013] According to some embodiments of the present invention, the aryl group is C6-C6. 20 Aryl group, preferably C6-C 10 Aryl, more preferably C6-C8 aryl.

[0014] According to some embodiments of the present invention, the substituents are selected from C1 to C2. 20 Alkyl, C3-C 20 cycloalkyl, C1-C 20 Alkoxy, C6~C 20 Aryl.

[0015] According to some embodiments of the present invention, the substituents are selected from C1 to C2. 10 Alkyl, C3-C 10 cycloalkyl, C1-C 10 Alkoxy, C6~C 12 Aryl.

[0016] According to some embodiments of the present invention, the substituents are selected from C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy, C6-C6 cycloalkyl, C3-C6 cycloalkyl, C4-C6 cycloalkyl, C5-C6 cycloalkyl, C6 ...5-C6 cycloalkyl, C5 12 Aryl.

[0017] According to some embodiments of the present invention, the substituent is selected from at least one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, hexyl, cyclopropyl, cyclopentyl, cyclohexyl, methoxy, ethoxy, propoxy, butoxy, phenyl, tolyl, ethylphenyl, propphenyl, biphenyl, and naphthalene.

[0018] According to some embodiments of the present invention, R1 and R2 are selected from cyclopropyl, cyclopentyl, cyclohexyl, and phenyl.

[0019] According to some embodiments of the present invention, R3 is selected from methyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, isopropyl, cyclopropyl, cyclopentyl, cyclohexyl, phenyl, and substituted phenyl.

[0020] According to some embodiments of the present invention, R3 is selected from tert-butyl, isopropyl, cyclohexyl, and phenyl.

[0021] According to some embodiments of the present invention, R4 and R5 may be the same or different, and each is independently selected from hydrogen, methyl, ethyl, propyl, and butyl.

[0022] According to some embodiments of the present invention, R4 and R5 may be the same or different, and each is independently selected from hydrogen, methyl, and ethyl.

[0023] In a second aspect, the present invention provides a method for preparing the alkenyl bisphosphine-bridged catalyst ligand described in the first aspect, comprising:

[0024]

[0025] S1: Compound a, compound b, and triethylamine undergo a first reaction in the first solvent to give compound c;

[0026] S2: Compound d and phosphorus trichloride undergo a second reaction in the second solvent to give compound e;

[0027] S3: Compounds c, e, and triethylamine undergo a third reaction in a third solvent to obtain an alkenyl bisphosphine-bridged catalyst ligand as shown in formula (I);

[0028] Wherein, R1 and R2 may be the same or different, and each is independently selected from aryl; R3 is selected from alkyl, cycloalkyl, and aryl; R4 and R5 may be the same or different, and each is independently selected from hydrogen and alkyl; the hydrogen on the carbon of the alkyl, cycloalkyl, or aryl group may optionally be replaced by one or more substituents.

[0029] According to some embodiments of the present invention, in step S1, the molar ratio of compound b, compound a, and triethylamine is 1:0.01 to 10:0.5 to 10, preferably 1:1 to 3:1 to 3.

[0030] According to some embodiments of the present invention, the first solvent comprises dichloromethane.

[0031] According to some embodiments of the present invention, in step S2, the molar ratio of compound d to phosphorus trichloride is 1:0.1 to 5, preferably 1:0.3 to 1.

[0032] According to some embodiments of the present invention, the second solvent includes diethyl ether.

[0033] According to some embodiments of the present invention, in step S3, the molar ratio of compound c, compound e, and triethylamine is 1:0.1 to 10:0.1 to 10, preferably 1:1 to 3:1 to 3.

[0034] According to some embodiments of the present invention, the third solvent includes dichloromethane.

[0035] Thirdly, the present invention provides a catalyst composition comprising the alkenyl bisphosphine-bridged catalyst ligand described in the first aspect, a transition metal compound, and an aluminum-containing co-catalyst.

[0036] According to some embodiments of the present invention, the transition metal compound is selected from at least one compound of chromium, molybdenum, iron, titanium, zirconium, and nickel.

[0037] According to some embodiments of the present invention, the transition metal compound is selected from at least one of chromium acetylacetonate, chromium isooctanoate, chromium trichloride (tetrahydrofuran), and chromium dichloride (dihydrofuran).

[0038] According to some embodiments of the present invention, the aluminum-containing cocatalyst is an organoaluminum compound.

[0039] According to some embodiments of the present invention, the aluminum-containing cocatalyst is selected from at least one of alkylaluminum compounds, alkoxyaluminum compounds, and alkylaluminum chloride compounds.

[0040] According to some embodiments of the present invention, the aluminum-containing co-catalyst is selected from at least one of methylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, diethylaluminum chloride, ethylaluminoxane, and modified methylaluminoxane.

[0041] According to some embodiments of the present invention, the aluminum-containing co-catalyst is selected from at least one of methylaluminoxane, triethylaluminum, and modified methylaluminoxane.

[0042] In this invention, the modified methylaluminoxane can be selected from alkyl-modified methylaluminoxanes, such as the conventional alkyl-modified methylaluminoxane MMAO in the art.

[0043] According to some embodiments of the present invention, the molar ratio of the transition metal compound, the alkenyl bisphosphine-bridged catalyst ligand of formula (I), and the aluminum-containing co-catalyst, based on the transition metal, is 1:(0.1-10):(1-1000), preferably 1:(0.25-2):(10-700), and more preferably 1:(0.5-2):(100-500).

[0044] Fourthly, the present invention provides the use of the catalyst composition described in the third aspect in the ethylene oligomerization reaction.

[0045] Fifthly, the present invention provides a method for ethylene oligomerization, comprising: continuously adding ethylene, hydrogen and an organic solvent into a reactor in the presence of the catalyst composition described in the third aspect to carry out an ethylene oligomerization reaction.

[0046] According to some embodiments of the present invention, in the ethylene oligomerization reaction, the concentration of the catalyst composition, calculated based on the volume of the organic solvent, is 0.1-10 μmol / L, expressed as a transition metal. For example, when the transition metal is Cr, the concentration of the catalyst composition, expressed as Cr, is 0.1-10 μmol / L.

[0047] In this invention, the reactor used for the ethylene oligomerization reaction can be a commonly used mixing reactor in the art, such as a batch reactor, tubular reactor, or loop reactor containing a stirrer or mixing system.

[0048] According to some embodiments of the present invention, the organic solvent includes aliphatic hydrocarbons and / or aromatic hydrocarbons.

[0049] According to some embodiments of the present invention, the aliphatic hydrocarbon compound is selected from at least one of straight-chain alkanes, branched-chain alkanes, and cycloalkanes; preferably from at least one of pentane, heptane, hexane, cyclohexane, and methylcyclohexane.

[0050] According to some embodiments of the present invention, the aromatic compound is selected from at least one of benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene, monochlorotoluene and their derivatives.

[0051] According to some embodiments of the present invention, in the above reaction, one or more of the catalyst compositions can be premixed and then added together to the reaction system, or each component can be added to the reaction system separately; or the catalyst ligand and transition metal compound can be pre-prepared into a complex and then added to the reaction system together with the aluminum-containing co-catalyst.

[0052] According to some embodiments of the present invention, in the ethylene oligomerization reaction, the volume ratio of hydrogen to ethylene is 1:(1 to 10000), preferably 1:(10 to 2000).

[0053] According to some embodiments of the present invention, the reaction temperature of the ethylene oligomerization reaction is 0-200°C, preferably 0-100°C, more preferably 30-100°C, and even more preferably 40-75°C.

[0054] According to some embodiments of the present invention, the ethylene pressure of the ethylene oligomerization reaction is 0.1 to 20.0 MPa, preferably 0.5 to 10.0 MPa, and more preferably 2.0 to 6.0 MPa.

[0055] According to some embodiments of the present invention, the ethylene oligomerization reaction includes ethylene trimerization and ethylene tetramerization.

[0056] The beneficial effects of this invention are at least as follows:

[0057] (1) The alkenyl bisphosphine-bridged catalyst ligand provided by the present invention has a novel structure, a simple preparation method, and a low cost.

[0058] (2) The catalyst composition provided by the present invention includes an alkenyl bisphosphine-bridged catalyst ligand, which can effectively catalyze the oligomerization reaction of ethylene. The reaction is mild and stable with good reproducibility and high selectivity for 1-octene. Moreover, the 1-hexene selectivity is good in C6 products, and the by-products such as cycloolefins and cyclizations are significantly reduced. It has good industrial application prospects and economic value. Detailed Implementation

[0059] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0060] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0061] In the various embodiments and comparative examples of the present invention, the performance data were tested according to the following test methods:

[0062] (1) Nuclear magnetic resonance: The Bruker AV400 nuclear magnetic resonance instrument was used for detection; the detection conditions were: deuterated chloroform as solvent.

[0063] (2) Room temperature test gas chromatography: Agilent 7890 chromatograph was used for detection; the detection conditions were: SE-54 column, high-purity nitrogen carrier gas, FID detector; the column temperature was programmed in two stages.

[0064] It should be noted that in this invention, Bu is n-butyl. t Bu is schottinki. i Pr is isopropyl, Ph is phenyl, Me is methyl, Cy is cyclohexyl, and Cp is cyclopentyl.

[0065] Preparation Example 1

[0066] Preparation of catalyst ligand I 1 (R1=R2=Ph,R3= i Pr, R4 = Me, R5 = H)

[0067] (1) Dissolve phosphorus trichloride (5 mmol) in diethyl ether (30 mL) and cool to -78 °C. Slowly add isopropenyl magnesium bromide (10 mL, 1 mol / L diethyl ether solution) to the solution. After the addition is complete, slowly raise the temperature to room temperature and stir for 5 hours to obtain diene phosphorus chloride solution for later use.

[0068] (2) At 0°C, diphenylphosphine chloride (15 mmol) was added dropwise to a solution of isopropylamine (18.8 mmol) and triethylamine (4.2 mL) in dichloromethane (10 mL) and stirred for 30 min. Then, the mixture was heated to room temperature and stirred overnight. The solvent was removed from the mixture and anhydrous diethyl ether (20 mL) was added to form a suspension. The suspension was filtered to obtain the filtrate, and then dried under reduced pressure to obtain the phosphine amine compound.

[0069] (3) Dissolve the phosphonamine compound (5 mmol) in dichloromethane (10 mL), add triethylamine (1.7 mL), and then add it dropwise to the diene phosphorus chloride stock solution from step (1) at 0 °C. After the addition is complete, raise the temperature to room temperature and stir overnight. Dry the mixture under vacuum and obtain a white solid powder, namely catalyst ligand I, by alkaline alumina column chromatography. 1 .

[0070] Preparation Example 2

[0071] Preparation of catalyst ligand I 2 (R1=R2=Ph,R3= t Bu, R4 = R5 = H)

[0072] The preparation method is the same as in Preparation Example 1, except that isopropenyl magnesium bromide is replaced with vinyl magnesium bromide and isopropylamine is replaced with tert-butylamine.

[0073] Preparation Example 3

[0074] Preparation of catalyst ligand I 3(R1=R2=Cy, R3=Cp, R4=R5=Me)

[0075] The preparation method is the same as in Preparation Example 1, except that diphenylphosphine chloride is replaced with dicyclohexylphosphine chloride, isopropylamine is replaced with cyclopentylamine, and isopropenyl magnesium bromide is replaced with butenyl magnesium bromide.

[0076] Preparation Example 4

[0077] Preparation of catalyst ligand I 4 (R1=R2=Cp, R3=Ph, R4=Me, R5=H)

[0078] The preparation method is the same as in Preparation Example 1, except that diphenylphosphine chloride is replaced with dicyclopentylphosphine chloride and isopropylamine is replaced with aniline.

[0079] Preparation Example 5

[0080] Preparation of catalyst ligand I 5 (R1 = R2 = 4-MePh, R3 = 2-biphenyl, R4 = Me, R5 = H)

[0081] The preparation method is the same as in Preparation Example 1, except that diphenylphosphine chloride is replaced with di-(4-methylphenyl)phosphine chloride and isopropylamine is replaced with 2-aminobiphenyl.

[0082] Preparation Example 6

[0083] Preparation of catalyst ligand I 6 (R1=R2=Ph,R3= i Pr, R4 = R5 = Bu)

[0084] The preparation method is the same as in Preparation Example 1, except that isopropenyl magnesium bromide is replaced with di-(butyl)vinyl magnesium bromide.

[0085] Example 1

[0086] A 300mL stainless steel polymerization reactor was used. The autoclave was heated to 80℃, evacuated, and purged several times with nitrogen. Then, it was purged with ethylene and cooled to the set temperature. Methylcyclohexane was then added at 60℃, along with 0.5μmol of chromium acetylacetone and 0.5μmol of catalyst ligand I. 1 The mixture, consisting of a co-catalyst modified methylaluminoxane (MMAO), has a total volume of 100 mL, including chromium acetylacetone and catalyst ligand I. 1 The molar ratio of ethylene to MMAO is 1:1:1000, the reaction pressure is controlled at 4 MPa, a mixture of ethylene and hydrogen is introduced (the volume ratio of hydrogen to ethylene is 1:1000), and the ethylene oligomerization reaction is carried out at 60°C.

[0087] Half an hour later, the reaction was complete. The system was cooled to room temperature, and the gaseous product was collected in a gas metering vessel, while the liquid product was collected in an Erlenmeyer flask. 1 mL of ethanol was added as a terminator to terminate the reaction. The gas and liquid products were then analyzed by gas chromatography. The experimental results are shown in Table 1.

[0088] Example 2

[0089] The preparation method is the same as in Example 1, except that catalyst ligand I is used. 1 Replace with catalyst ligand I 2 The experimental results are shown in Table 1.

[0090] Example 3

[0091] The preparation method is the same as in Example 1, except that catalyst ligand I is used. 1 Replace with catalyst ligand I 3 The experimental results are shown in Table 1.

[0092] Example 4

[0093] The preparation method is the same as in Example 1, except that catalyst ligand I is used. 1 Replace with catalyst ligand I 4 The experimental results are shown in Table 1.

[0094] Example 5

[0095] The preparation method is the same as in Example 1, except that catalyst ligand I is used. 1 Replace with catalyst ligand I 5 The experimental results are shown in Table 1.

[0096] Example 6

[0097] The preparation method is the same as in Example 1, except that catalyst ligand I is used. 1 Replace with catalyst ligand I 6 The experimental results are shown in Table 1.

[0098] Table 1

[0099]

[0100] As can be seen from the data in Table 1, the catalytic activity of the catalyst composition provided by the present invention is 1.1 × 10⁻⁶. 8 g·mol(Cr) -1 ·h -1The above-mentioned results demonstrate that the selectivity for 1-octene can reach over 77 wt%, and the content of 1-hexene in C6 exceeds 90 wt%, with the total selectivity of 1-hexene and 1-octene exceeding 90 wt%. This represents a significant increase in the content of 1-hexene in C6 while maintaining high 1-octene selectivity. Compared to existing PNP or PCCP ligands, the catalyst composition including the alkenyl bisphosphine-bridged catalyst ligand provided by this invention exhibits superior catalytic performance. The alteration of the catalyst ligand structure affects the ligand's coordination ability and electronic effects, making the complex formed with the metal more suitable for ethylene oligomerization reactions, thus significantly improving catalytic performance and effectiveness.

[0101] The above experimental results show that the catalyst composition provided by this invention exhibits high selectivity for 1-octene and 1-hexene in the products of ethylene oligomerization. Since the polyolefin field, especially new materials such as POE, C8-LLDPE, and PAO, urgently requires copolymer-grade high-purity 1-octene or 1-hexene, the process technology with higher overall selectivity for 1-octene and 1-hexene has significant economic and social value.

[0102] 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. An alkenyl bisphosphine-bridged catalyst ligand, the structure of which is shown in formula (I), （I） wherein R1 and R2 may be the same or different, and each is independently selected from C3 to C. 20 cycloalkyl, C6~C 20 Aryl; R3 is selected from C1~C 20 Alkyl, C3~C 20 cycloalkyl, C6~C 20 Aryl group; R4 and R5 may be the same or different, and each is independently selected from hydrogen, C1~C2. 20 Alkyl group; the hydrogen atom on the carbon of the alkyl, cycloalkyl, or aryl group is optionally substituted with one or more substituents; The substituent is selected from C1~C1. 20 Alkyl, C3~C 20 cycloalkyl, C1~C 20 Alkoxy, C6~C 20 Aryl.

2. The alkenyl bisphosphine-bridged catalyst ligand according to claim 1, characterized in that, said alkyl is Ci-C 10 alkyl; and / or the cycloalkyl group is C3-C6 10 cycloalkyl; and / or the aryl group is a C6-Ci2 12 aryl; And / or, the substituents are selected from C1 to C2. 10 Alkyl, C3~C 10 cycloalkyl, C1~C 10 Alkoxy, C6~C 12 Aryl.

3. The alkenyl bisphosphine bridged catalyst ligand according to claim 1, wherein, The alkyl group is a C1-C6 alkyl group; And / or, the cycloalkyl group is a C3-C6 cycloalkyl group; And / or, the aryl group is a C6-C8 aryl group; And / or, the substituents are selected from C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy, C6-C6 alkyl, C7-C8 alkyl, C9-C9 alkyl, C1-C9 alkyl, C9 ... 12 Aryl.

4. The alkenyl bisphosphine bridged catalyst ligand of claim 1, wherein, The substituent is selected from at least one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, hexyl, cyclopropyl, cyclopentyl, cyclohexyl, methoxy, ethoxy, propoxy, butoxy, phenyl, tolyl, ethylphenyl, propphenyl, biphenyl, and naphthyl.

5. The alkenyl bisphosphine bridged catalyst ligand according to any one of claims 1 to 4, wherein, R1 and R2 are selected from cyclopropyl, cyclopentyl, cyclohexyl, and phenyl. And / or, R3 is selected from methyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, isopropyl, cyclopropyl, cyclopentyl, cyclohexyl, phenyl, substituted phenyl; And / or, R4 and R5 may be the same or different, and each may be independently selected from hydrogen, methyl, ethyl, propyl, and butyl.

6. The alkenyl bisphosphine bridged catalyst ligand according to claim 5, wherein, R3 is selected from tert-butyl, isopropyl, cyclohexyl, and phenyl. And / or, R4 and R5 may be the same or different, and each may be independently selected from hydrogen, methyl, or ethyl.

7. The method for preparing the alkenyl bisphosphine-bridged catalyst ligand according to any one of claims 1-6, characterized in that, include: S1: Compound a, compound b, and triethylamine undergo a first reaction in the first solvent to give compound c; S2: Compound d and phosphorus trichloride undergo a second reaction in the second solvent to give compound e; S3: Compounds c, e, and triethylamine undergo a third reaction in a third solvent to obtain an alkenyl bisphosphine-bridged catalyst ligand as shown in formula (I).

8. The method for preparing the alkenyl bisphosphine-bridged catalyst ligand according to claim 7, characterized in that, In step S1, the molar ratio of compound b, compound a, and triethylamine is 1:0.01~10:0.5~10; And / or, the first solvent is dichloromethane; And / or, in step S2, the molar ratio of compound d to phosphorus trichloride is 1:0.1~5; And / or, the second solvent is diethyl ether; And / or, in step S3, the molar ratio of compound c, compound e, and triethylamine is 1:0.1~10:0.1~10; And / or, the third solvent is dichloromethane.

9. The method for preparing the alkenyl bisphosphine-bridged catalyst ligand according to claim 8, characterized in that, In step S1, the molar ratio of compound b, compound a, and triethylamine is 1:1~3:1~3; And / or, in step S2, the molar ratio of compound d to phosphorus trichloride is 1:0.3~1; And / or, in step S3, the molar ratio of compound c, compound e, and triethylamine is 1:1~3:1~3.

10. A catalyst composition characterized in that, Includes the alkenyl bisphosphine-bridged catalyst ligand, transition metal compound, and aluminum-containing cocatalyst as described in any one of claims 1-6.

11. The catalyst composition of claim 10, wherein, The transition metal compound is selected from at least one compound of chromium, molybdenum, iron, titanium, zirconium, and nickel.

12. The catalyst composition according to claim 10, characterized in that, The transition metal compound is selected from at least one of chromium acetylacetonate, chromium isooctanoate, chromium trichloride (tetrahydrofuran), and chromium dichloride (dihydrofuran).

13. The catalyst composition of any of claims 10-12, wherein, The aluminum-containing cocatalyst is an organoaluminum compound.

14. The catalyst composition of any of claims 10-12, wherein, The aluminum-containing cocatalyst is selected from at least one of alkylaluminum compounds, alkoxyaluminum compounds, and alkylaluminum chloride compounds.

15. The catalyst composition of any of claims 10-12, wherein, The aluminum-containing cocatalyst is selected from at least one of methylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, diethylaluminum chloride, ethylaluminoxane, and modified methylaluminoxane.

16. The catalyst composition of any of claims 10-12, wherein, The aluminum-containing cocatalyst is selected from at least one of methylaluminoxane, triethylaluminum, and modified methylaluminoxane.

17. The catalyst composition of any of claims 10-12, wherein, The molar ratio of the transition metal compound, the alkenyl bisphosphine-bridged catalyst ligand shown in formula (I), and the aluminum-containing co-catalyst, based on the transition metal, is 1:(0.1-10):(1-1000).

18. The catalyst composition of any of claims 10-12, wherein, The molar ratio of the transition metal compound, the alkenyl bisphosphine-bridged catalyst ligand shown in formula (I), and the aluminum-containing co-catalyst, based on the transition metal, is 1:(0.25-2):(10-700).

19. The catalyst composition of any of claims 10-12, wherein, The molar ratio of the transition metal compound, the alkenyl bisphosphine-bridged catalyst ligand shown in formula (I), and the aluminum-containing co-catalyst, based on the transition metal, is 1:(0.5-2):(100-500).

20. The use of the catalyst composition according to any one of claims 10-19 in the ethylene oligomerization reaction.

21. A process for the oligomerization of ethylene comprising: In the presence of the catalyst composition according to any one of claims 10-19, ethylene, hydrogen and organic solvent are continuously added to the reactor to carry out an ethylene oligomerization reaction.

22. The method of claim 21, wherein, The volume ratio of hydrogen to ethylene is 1:(1~10000).

23. The method of claim 21, wherein, The volume ratio of hydrogen to ethylene is 1:(10~2000).

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