A catalyst containing tetraphosphine ligand for selective tetramerization of ethylene and its preparation method and application

Abstract

The present application relates to a catalyst for selective tetramerization of ethylene containing tetraphosphine ligand and its preparation method and application, the catalyst includes ligand, transition metal compound and activator, wherein, the chemical structure formula of ligand is as shown in the following formula (I): in the formula, groups R1 and R2 are each independently selected from hydrogen, halogen, alkyl; groups R3 to R 10 Each is independently selected from an alkyl, alkenyl or aromatic group. The catalyst is used for selective tetramerization of ethylene to generate 1-octene, which is carried out in an inert solvent. Compared with the prior art, the present application has the advantages of low cocatalyst dosage, high activity and 1-octene selectivity, high total selectivity of 1-hexene and 1-octene, and low polymer content.

Description

Technical Field

[0001] This invention relates to the field of ethylene oligomerization technology, specifically to a catalyst for selective tetramerization of ethylene containing tetraphosphine ligands, its preparation method, and its application. Background Technology

[0002] Linear α-olefins (LAOs) are important chemical raw materials used in the preparation of lubricants, surfactants, etc. 1-Hexene and 1-Octene are indispensable comonomers in the synthesis of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) (the comonomer content in LLDPE is generally 8-10%, and in HDPE it is 1-2%). Traditional ethylene oligomerization catalysis mainly follows the Cossee-Arlman mechanism, where ethylene molecules insert into the catalyst metal center and the linear chain grows. The resulting linear α-olefins usually exhibit a normal distribution, requiring separation and purification for industrial applications. Representative systems include titanium-based, zirconium-based, and iron-based systems. Chromium-catalyzed ethylene oligomerization, however, mainly follows a metal ring mechanism, producing α-olefins with a Schulz-Flory distribution, where the product at the peak has a higher proportion.

[0003] As research has deepened, it has been discovered that the structure of the catalyst plays a crucial role in product distribution; in other words, changes in the ligand skeleton and substituents determine the selective oligomerization effect of ethylene. In recent years, research in this field has focused on the catalytic mechanism of selective oligomerization of ethylene and ligand design, yielding some important results. In 2002, British Petroleum reported the use of PNP-type ligands with the structure PAr2N(R)PAr2 (Ar being an ortho-methoxy-substituted aryl group) for chromium-catalyzed highly selective trimerization of ethylene to 1-hexene (Chem. Commun. 2002, 858-859). In 2004, through substituent modification, Sasol successfully achieved ethylene tetramerization using the aforementioned PNP-type ligand / chromium catalytic system, achieving a 1-octene selectivity of up to 67.5% (J. Am. Chem. Soc. 2004, 126, 14712). In 2008, Sasol synthesized a series of carbon-bridged bisphosphine ligands for the selective tetramerization of ethylene (J. Mol. Catal. A: Chem. 2008, 283, 114). Among them, the phenyl-bridged bisphosphine ligand showed relatively good catalytic performance, with an activity reaching 2240 kg / g Cr / h. However, the selectivity for 1-octene was only 56.8%, and the polymer content in the product was relatively high (0.9%). All of the above-mentioned selective oligomerization systems for ethylene used MAO or MMAO as co-catalysts. These co-catalysts require large quantities and are expensive, which is not conducive to industrial production. In addition, the above-mentioned homogeneous catalysts are prone to bimolecular deactivation, inhibiting catalyst activity. Furthermore, the deactivated catalyst can catalyze the polymerization of ethylene into polymers, affecting the normal operation of the equipment. Summary of the Invention

[0004] The purpose of this invention is to overcome at least one of the defects of the prior art and provide a tetraphosphine-containing ethylene selective tetramerization catalyst with low co-catalyst dosage, high activity and 1-octene selectivity, high total selectivity of 1-hexene and 1-octene, and low polymer content, as well as its preparation method and application.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] To reduce the amount of co-catalyst and improve the activity of the catalytic system, this invention innovatively introduces four P-RR' groups at the 1, 2, 4, and 5 positions of the phenyl group (R and R' can be the same or different, representing R3-R). 10Each ligand (selected independently from alkyl, alkenyl, or aromatic groups) has two coordination centers, effectively suppressing bimolecular deactivation reactions, significantly improving catalyst activity, reducing polymer content, and decreasing MMAO dosage. Simultaneously, this invention introduces sterically tunable alkyl groups and ortho-haloaryl groups onto the phosphorus atom. By introducing ortho-haloaryl groups and sterically less hindrance alkyl groups, this invention successfully improved the 1-octene selectivity of this catalytic system to 75.6%, and the total selectivity of 1-hexene and 1-octene to 95.8%, while further enhancing catalytic activity to a maximum of 4680 kg / g Cr / h. The specific scheme is as follows:

[0007] A catalyst for the selective tetramerization of ethylene containing a tetraphosphine ligand, the catalyst comprising the ligand, a transition metal compound, and an activator, wherein the chemical structural formula of the ligand is shown in formula (I) below:

[0008]

[0009] In the formula,

[0010] Groups R1 and R2 are each independently selected from hydrogen, halogen, or alkyl groups;

[0011] Groups R3 to R 10 Each group is independently selected from alkyl, alkenyl, or aromatic groups.

[0012] Furthermore, the alkyl group is C1-C. 30 Alkyl groups, specifically including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, cyclopentyl, n-hexyl, sec-hexyl, isohexyl, cyclohexyl, n-heptyl, cycloheptyl, n-octyl, n-decyl, 2-methylcyclopentyl, or 2,6-dimethylcyclohexyl.

[0013] Furthermore, the alkenyl group is C1-C. 30 The alkenyl group specifically includes vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-2-butenyl, 2-methyl-1-butenyl, 3-methyl-2-butenyl, 5-hexenyl, 2-cyclohexenyl, 3-cyclohexenyl, or 2-methyl-2-cyclohexenyl; the halogen is fluorine, chlorine, bromine, or iodine.

[0014] Furthermore, the aromatic group is C4-C. 30Aryl groups and their derivatives, specifically including phenyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, 2,6-difluorophenyl, 2,5-difluorophenyl, 2,4-difluorophenyl, 2,3-difluorophenyl, 3,4-difluorophenyl, 3,5-difluorophenyl, 2,6-dichlorophenyl, 2,5-dichlorophenyl, 2,4-dichlorophenyl, 2,3-dichlorophenyl, 3,4-dichlorophenyl, 3,5-dichlorophenyl, p-ethylphenyl, o-ethylphenyl, m-ethylphenyl Naphthyl, 2,4-dimethylphenyl, 2,4-diisopropylphenyl, 2,4-di-tert-butylphenyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl, 3,5-dimethylphenyl, 3,5-di-tert-butylphenyl, 2,4,6-trimethylphenyl, naphthyl, anthraceneyl, biphenyl, 7-fluoro-1-naphthyl, 8-fluoro-1-naphthyl, 7-chloro-1-naphthyl, 8-chloro-1-naphthyl, 9-fluoro-1-anthrayl, 9-chloro-1-anthrayl, 8-fluoro-1-anthrayl or 8-chloro-1-anthrayl;

[0015] Furthermore, the groups R3 to R 10 At least one of them is not phenyl.

[0016] The transition metal in the catalyst system of this invention can be a transition metal compound commonly used in the art. The metal atom in the transition metal compound serves as the active metal center and plays an important role in the catalytic process. Further, the transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, nickel, or palladium; more preferably, the transition metal in the transition metal compound is selected from chromium. Specifically, the corresponding transition metal compound can be any chromium compound capable of enabling oligomerization, and selectable chromium compounds include those with the general formula CrR. n The compound shown has R in its formula. n R is an organic anion or a neutral molecule. n It typically contains 1-15 carbon atoms, where n is an integer from 0 to 6, and the valence state of Cr is between 0 and 6. Specifically, R... n The functional group is an organic compound or other functional group containing a carboxyl group, a β-diketone group, or a hydrocarbon group. From the perspective of ease of solubility and handling, more suitable chromium compounds include one of chromium trichloride-tris(tetrahydrofuran) complex, (benzene)tricarbonylchromium, chromium octanoate (III), chromium hexacarbonyl, chromium acetylacetonate (III), chromium naphthenate (III), chromium 2-ethylhexanoate (III), chromium acetate (III), 2,2,6,6-tetramethylheptanedione (III), and chromium chloride (III). Preferably, the chromium compound is selected from chromium trichloride-tris(tetrahydrofuran) complex, chromium acetylacetonate (III), and chromium 2-ethylhexanoate (III).

[0017] The activator in the catalyst system of this invention plays an activating role in the catalyst system. The activator used in this invention can be any compound that forms an active catalyst when mixed with ligands and transition metal compounds. The activator can be used alone or in combination. The activator includes alkylaluminum compounds, aluminoxane compounds, or organoboron compounds; the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100):1; the molar ratio of the activator to the transition metal element in the transition metal compound is (1-10000):1. Further, the aluminoxane compound specifically includes modified methylaluminoxane MMAO-3A; the molar ratio of the activator to the transition metal element in the transition metal compound is (250-500):1.

[0018] Furthermore, the activator includes alkylaluminum compounds, aluminum oxane compounds, or organoboron compounds.

[0019] Furthermore, the activator includes one or a mixture of several of alkylaluminum compounds, aluminoxane compounds, organoboron compounds, inorganic acids, or inorganic salts.

[0020] Specifically, the activator can be an alkylaluminum compound, which can be various trialkylaluminum compounds, such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, or tri-n-octylaluminum; the alkylaluminum compound can also be an alkylaluminum halide, an alkylaluminum hydride, or an alkylaluminum sesquichloride, such as diethylaluminum chloride (AlEt2Cl) and triethylaluminum chloride (Al2Et3Cl3).

[0021] Specifically, the activator can be an aluminum oxane compound, which is typically prepared by mixing water with an alkyl aluminum compound (e.g., trimethylaluminum). The prepared aluminum oxane oligomer can be a linear compound, a cyclic compound, a cage-like compound, or a mixture thereof. Suitable aluminum oxane compounds can be selected from methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, modified aluminum oxanes, and methylaluminoxane DMAO with volatile components removed, etc.

[0022] Specifically, suitable boron compounds may include cycloboroxanes, triethylborane, triphenylborane, tris(pentafluorophenyl)borane, etc. Organoboron compounds may be used in combination with organoaluminum compounds.

[0023] Preferably, the activator can be selected from methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, and modified methylaluminoxane (MMAO).

[0024] Furthermore, the aluminum oxane compound specifically includes modified methylaluminoxane MMAO-3A.

[0025] Furthermore, the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100):1, preferably (0.1-10):1, and more preferably (0.5-2):1;

[0026] The molar ratio of the activator to the transition metal element in the transition metal compound is (1-10000):1, preferably (1-2000):1, more preferably (100-1000):1, and most preferably (200-400):1.

[0027] A method for preparing a catalyst for selective tetramerization of ethylene containing tetraphosphine ligands as described above, the method comprising: pre-mixing or directly adding the ligand, transition metal compound and activator into the reaction system for in-situ synthesis, thereby obtaining the catalyst for selective tetramerization of ethylene containing tetraphosphine ligands.

[0028] In some embodiments, an active catalyst can be provided by simultaneously or in any order mixing of a ligand having the chemical formula (I), a transition metal compound, and an activator, with or without a solvent. The mixing of the catalyst components can be carried out at temperatures ranging from -20 to 250°C, and the presence of olefins during the mixing process typically exhibits a protective effect, thereby providing improved catalytic performance. Furthermore, the mixing of the catalyst components can be carried out within a temperature range of approximately 20–100°C.

[0029] In some embodiments, separable metal-ligand complexes can be prepared in situ from a transition metal compound and a ligand represented by formula (I). The metal-ligand complex is then added to a reaction medium. Alternatively, a chromium compound and the ligand can be added separately to the reactor, thereby preparing a chromium-ligand complex in situ. In-situ preparation of the complex refers to the preparation of the complex in the medium in which the catalytic reaction occurs, followed by the addition of an activator.

[0030] Application of a catalyst for the selective tetramerization of ethylene containing a tetraphosphine ligand as described above, the catalyst being used for the selective tetramerization of ethylene to produce 1-octene, the reaction being carried out in an inert solvent at a temperature of 0-200°C and a pressure of 10-5000 psig, wherein the concentration of the transition metal in the transition metal compound in the inert solvent is 0.01-10000 μmol / L; further, the reaction temperature is 40-80°C and the pressure is 300-500 psig.

[0031] Furthermore, the reaction is carried out in an inert solvent at a temperature of 0-200°C, preferably 10-120°C, more preferably 15-100°C, further preferably 20-80°C, and ultimately preferably 20-50°C. The reaction pressure is 10-5000 psig, preferably 100-2000 psig, more preferably 300-1000 psig, and ultimately preferably 400-600 psig. The concentration of the transition metal in the transition metal compound in the inert solvent is 0.01-10000 μmol / L, preferably 1-500 μmol / L, and more preferably 0.1-10 μmol / L.

[0032] The inert solvent includes one or more of alkanes, aromatics, alkenes, or ionic liquids. Typical solvents include, but are not limited to, benzene, toluene, xylene, cumene, chlorobenzene, dichlorobenzene, fluorobenzene, n-heptane, n-hexane, methylcyclohexane, cyclohexane, 1-hexene, 1-octene, etc., with toluene and methylcyclohexane being preferred.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) This invention creatively introduces four P-RR' groups at the 1, 2, 4, and 5 positions of the phenyl group (R and R' can be the same or different, representing R3-R). 10 Each ligand is independently selected from alkyl, alkenyl or aromatic groups. The resulting ligand has two coordination centers, which can effectively inhibit the bimolecular deactivation reaction, greatly improve the catalyst activity, reduce the polymer content, and reduce the amount of MMAO used, thus reducing production costs.

[0035] (2) The present invention introduces sterically tunable alkyl groups and ortho-haloaryl groups onto the phosphorus atom. By introducing ortho-haloaryl groups and alkyl groups with less steric hindrance, the present invention effectively improves the 1-octene selectivity, 1-hexene and total 1-octene selectivity and catalytic activity of the catalytic system. Detailed Implementation

[0036] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, % in the text can be considered as mass percentage.

[0037] A catalyst for the selective tetramerization of ethylene containing a tetraphosphine ligand, its preparation method, and its application are disclosed. The preparation method involves pre-mixing or directly adding the ligand, a transition metal compound, and an activator to the reaction system for in-situ synthesis, thereby obtaining the catalyst for the selective tetramerization of ethylene containing the tetraphosphine ligand. This catalyst is used for the selective tetramerization of ethylene to produce 1-octene. The reaction is carried out in an inert solvent at a temperature of 0-200°C and a pressure of 10-5000 psig. The concentration of the transition metal in the transition metal compound in the inert solvent is 0.01-10000 μmol / L. The inert solvent includes one or more of alkanes, aromatics, alkenes, or ionic liquids. In some embodiments, the reaction temperature is 40-80°C and the pressure is 300-500 psig.

[0038] The chemical structural formula of the ligand is shown in formula (I) below:

[0039]

[0040] In the formula, groups R1 and R2 are each independently selected from hydrogen, halogen, and alkyl; groups R3 to R... 10 Each group is independently selected from alkyl, alkenyl, or aromatic groups. The groups R3 to R... 10 At least one of them is not phenyl.

[0041] The transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, nickel, or palladium; the activator includes alkylaluminum compounds, aluminoxane compounds, or organoboron compounds; the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100):1; the molar ratio of the activator to the transition metal element in the transition metal compound is (1-10000):1. The aluminoxane compound specifically includes modified methylaluminoxane MMAO-3A; the molar ratio of the activator to the transition metal element in the transition metal compound is (250-500):1.

[0042] Example 1

[0043] The preparation of complex 1 is carried out in the following steps:

[0044] (1) Preparation of (2-F-Ph)2PCl

[0045] Magnesium powder (0.88 g, 36 mmol) was placed in a Schlenk reaction tube. Tetrahydrofuran (10 mL) was added under nitrogen protection, followed by 5 drops of 1,2-dibromoethane. After reacting for 3 minutes, a tetrahydrofuran solution (40 mL) of o-bromofluorobenzene (5.25 g, 30 mmol) was slowly added at 0 °C. The reaction was allowed to proceed for 1 hour, and the mixture was filtered to obtain a grayish-black tetrahydrofuran solution of o-fluorophenyl magnesium bromide (30 mmol). Phosphorus trichloride (2.06 g, 15 mmol) was dissolved in tetrahydrofuran (10 mL) and cooled to -78 °C. The prepared tetrahydrofuran solution of o-fluorophenyl magnesium bromide (30 mmol) was slowly added (50 mL). After the addition was complete, the mixture was slowly heated to room temperature and stirred for 5 hours until the reaction was complete. The solvent was removed, and the mixture was dissolved in diethyl ether (40 mL), filtered through anhydrous and oxygen-free channels, and the solvent was removed again to obtain a pale yellow oily product, which was directly used in the next reaction.

[0046] (2) Ligand L 1 Preparation

[0047] In a 50 mL Schlenk flask filled with argon, 1,4-dibromo-2,5-difluorobenzene (7.5 mmol, 2.0 g) and 30 mL of redistilled tetrahydrofuran were added. The mixture was stirred and cooled to -95 °C. Diisopropylaminolithium (6.0 mL, 2.5 M hexane solution, 15.0 mmol) was added dropwise to the solution. The mixture was stirred at this temperature for 10 minutes. Diphenylphosphine chloride (15 mmol, 3.3 g) was added. The mixture was allowed to react at this temperature for 1 hour after the addition was complete. The mixture was then moved to room temperature and reacted overnight. Water (20 mL) and dichloromethane (20 mL × 3) were added. The mixture was extracted, and the organic phase was dried and filtered. The filtrate was dried under vacuum and purified by silica gel column chromatography to give an orange-yellow solid product (3.3 g, 90.0%). In a 50 mL Schlenk flask filled with argon, the above-mentioned orange-yellow solid product and redistilled tetrahydrofuran (30 mL) were added, stirred, and cooled to -78 °C. Butyllithium (5.4 mL, 2.5 M hexane solution, 13.5 mmol) was added dropwise, and the mixture was stirred at this temperature for 1 h. Then, (2-F-Ph)₂PCl (15 mmol) prepared above was added dropwise. After the addition was complete, the mixture was reacted at this temperature for 1 h, then moved to room temperature and reacted overnight. Water (20 mL) and dichloromethane (20 mL × 3) were added, and the mixture was extracted. The organic phase was dried and filtered, and the filtrate was dried under vacuum and purified by silica gel column chromatography to obtain the yellow solid product L. 1 (4.0g, 67.0%). 1 H NMR (400MHz, CDCl3) δ7.13-7.15(m,12H),7.21-7.22(m,8H),7.28-7.32(m,2H),7.44-7.47(m,12H),7.65-7.68(m,4H).

[0048]

[0049] (3) Preparation of complex 1

[0050] In a dry Schlenk reaction tube filled with argon, ligand L was added. 1 (443.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 577.9 mg (0.43 mmol, 86.0%) of blue powder.

[0051] Example 2

[0052] The preparation of complex 2 follows these steps:

[0053] (1) Preparation of (2-F-Ph)(Ph)PCl

[0054] Phosphorus diphenyl chloride (1.25 g, 7 mmol) was dissolved in tetrahydrofuran (10 mL) and cooled to -78 °C. A tetrahydrofuran solution (10 mL) of the prepared o-fluorophenyl magnesium bromide (7 mmol) was slowly added to the solution. After the addition was complete, the solution was slowly heated to room temperature and stirred for 5 hours until the reaction was complete. The solvent was then removed, and the solution was dissolved in ether (40 mL), filtered through anhydrous and oxygen-free filter, and the solvent was removed again to obtain a pale yellow oily product.

[0055] (2) Ligand L 2 Preparation

[0056] Reference ligand L 1 The preparation method uses (2-F-Ph)(Ph)PCl (15.0 mmol) instead of (2-F-Ph)2PCl to obtain a colorless oily product L. 2 (4.8g, 83.7%). 1 H NMR (400MHz, CDCl3) δ7.13-7.15(m,14H),7.21-7.22(m,4H),7.29-7.32(m,2H),7.44-7.47(m,18H),7.46-7.67(m,2H).

[0057]

[0058] (3) Preparation of complex 2

[0059] In a dry Schlenk reaction tube filled with argon, ligand L was added. 2(425.0 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 555.9 mg (0.43 mmol, 85.0%) of blue powder.

[0060] Example 3

[0061] The preparation of complex 3 is carried out in the following steps:

[0062] (1) Ligand L 3 Preparation

[0063] Reference ligand L 1 The preparation method uses diethylphosphorus chloride (1.1 g, 15.0 mmol) instead of (2-F-Ph)2PCl to obtain a yellow oily product L. 3 (3.2g, 75.2%). 1 H NMR (400MHz, CDCl3) δ0.98-1.02(m,12H),1.65-1.68(m,8H),7.14-7.16(m,8H),7.33-7.37(m,2H),7.44-7.47(m,12H).

[0064]

[0065] (2) Preparation of complex 3

[0066] In a dry Schlenk reaction tube filled with argon, ligand L was added. 3 (311.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 426.6 mg (0.40 mmol, 79.0%) of blue powder.

[0067] Example 4

[0068] The preparation of complex 4 is carried out in the following steps:

[0069] (1) Preparation of (Ph)(Et)PCl

[0070] Phenylated phosphorus dichloride (1.79 g, 10 mmol) was added to a dry, nitrogen-filled 50 mL Schlenk tube. 10 mL of tetrahydrofuran was added to dissolve it. The solution was then cooled to -78 °C. Ethyl magnesium chloride (10.0 mL, 1.0 M in THF, 10 mmol) was slowly added. After the addition was complete, the reaction was continued at this temperature for 30 minutes. The temperature was then raised to room temperature and the reaction was allowed to proceed for 8 hours. The solution was used directly without purification after the reaction was completed.

[0071] (2) Ligand L 4 Preparation

[0072] Reference ligand L 1 The preparation method uses (Ph)(Et)PCl (15.0 mmol) instead of (2-F-Ph)2PCl to obtain the yellow solid product L. 4 (3.4g, 69.2%). 1 H NMR (400MHZ, CDCl3) δ0.90-1.02(m,6H),1.31-1.61(m,4H),7.10-7.22(m,12H),7.30-7.38(m,2H),7.41-7.44(m,14H),7.46-7.51(m,4H).

[0073]

[0074] (3) Preparation of complex 4

[0075] In a dry Schlenk reaction tube filled with argon, ligand L was added. 4 (359.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 464.5 mg (0.40 mmol, 79.0%) of blue powder.

[0076] Example 5

[0077] The preparation of complex 5 is carried out in the following steps:

[0078] (1) Ligand L 5 Preparation

[0079] Reference ligand L 1 The preparation method uses (Ph)(Et)PCl (15.0 mmol) instead of diphenylphosphine chloride and (Ph)(Et)PCl (15.0 mmol) instead of (2-F-Ph)2PCl to obtain a pale yellow solid product L.5 (3.6g, 80.0%). 1 H NMR (400MHZ, CDCl3) δ0.93-1.02(m,12H),1.42-1.57(m,8H),7.12-7.19(m,8H),7.25-7.38(m,2H),7.41-7.46(m,12H).

[0080]

[0081] (2) Preparation of complex 5

[0082] In a dry Schlenk reaction tube filled with argon, ligand L was added. 5 (311.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 415.8 mg (0.39 mmol, 77.0%) of blue powder.

[0083] Example 6

[0084] The preparation of complex 6 is carried out in the following steps:

[0085] (1) Ligand L 6 Preparation

[0086] Reference ligand L 1 The preparation method uses (2-F-Ph)(Ph)PCl (15.0 mmol) instead of diphenylphosphine chloride and diethylphosphine chloride (15 mmol) instead of (2-F-Ph)2PCl to obtain a pale yellow solid product L. 6 (2.2g, 49.2%). 1 H NMR (400MHz, CDCl3) δ7.13-7.15(m,14H),7.21-7.22(m,4H),7.29-7.32(m,2H),7.44-7.47(m,18H),7.46-7.67(m,2H).

[0087]

[0088] (2) Preparation of complex 6

[0089] In a dry Schlenk reaction tube filled with argon, ligand L was added. 6(329.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 446.4 mg (0.40 mmol, 79.0%) of blue powder.

[0090] Example 7

[0091] The preparation of complex 7 is carried out in the following steps:

[0092] (1) Ligand L 7 Preparation

[0093] Reference ligand L 6 The preparation method uses diisopropylphosphorus chloride (15.0 mmol) instead of diethylphosphorus chloride to obtain a yellow oily product L. 7 (3.7g, 79.2%). 1 H NMR(400MHZ,CDCl3)δ0.88-1.02(m,24H),1.45-1.72(m,4H),7.11-7.17(m,4H ),7.19-7.25(m,2H),7.32-7.39(m,2H),7.41-7.49(m,6H),7.65-7.72(m,2H).

[0094]

[0095] (2) Preparation of complex 7

[0096] In a dry Schlenk reaction tube filled with argon, ligand L was added. 7 (343.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 460.5 mg (0.40 mmol, 80.5%) of blue powder.

[0097] Example 8

[0098] The preparation of complex 8 is carried out in the following steps:

[0099] (1) Ligand L 8 Preparation

[0100] Reference ligand L 6The preparation method uses (Ph)(Et)PCl (15.0 mmol) instead of diethylphosphorus chloride to obtain a yellow oily product L. 8 (2.6g, 50.9%). 1 H NMR (400MHz, CDCl3) δ0.86-1.04(m,6H),1.37-1.51(m,4H),7.13-7.19(m,14H),7.33-7.49(m,14H),7.62~7.71(m,2H).

[0101]

[0102] (2) Preparation of complex 8

[0103] In a dry Schlenk reaction tube filled with argon, ligand L was added. 8 (377.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 545.4 mg (0.45 mmol, 90.2%) of blue powder.

[0104] Example 9

[0105] The preparation of complex 9 is carried out in the following steps:

[0106] (1) Ligand L 9 Preparation

[0107] In a dry Schlenk reaction tube filled with argon, small pieces of sodium (920.0 mg, 40 mmol) and redistilled tetrahydrofuran (50 mL) were added. Diphenylphosphine chloride (4.4 g, 20 mmol) was slowly added dropwise, and the mixture was heated under reflux for 6 h. Excess sodium was removed by filtration in an anhydrous and oxygen-free environment. 1,2,4,5-Tetrafluorobenzene (0.3 g, 2 mmol) was slowly added dropwise to the solution. After the addition was complete, the mixture was heated under reflux overnight. Water (20 mL) and dichloromethane (20 mL × 3) were added, and the mixture was extracted. The organic phase was dried and filtered. The filtrate was dried under vacuum and purified by silica gel column chromatography to obtain a yellow solid product L. 9 (1.1g, 65.0%). 1 H NMR(CDCl3)δ7.19-7.13(m,8H),7.07(m,16H),6.96-6.89(m,18H).

[0108]

[0109] (2) Preparation of complex 9

[0110] In a dry Schlenk reaction tube filled with argon, ligand L was added. 9 (407.1 mg, 0.5 mmol) and CrCl3(THF)3 (374.7 mg, 1.0 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 586.4 mg (0.46 mmol, 92.2%) of blue powder.

[0111] Example 10

[0112] The preparation of complex 10 is carried out in the following steps:

[0113] (1) Ligand L 10 Preparation

[0114] In a dry, nitrogen-filled 50 mL Schlenk tube, o-bromoiodobenzene (2.83 g, 10.0 mmol), diphenylphosphine (1.86 g, 10.0 mmol), Pd(PPh3)4 (58 mg, 0.05 mmol), and triethylamine (1.11 g, 11.0 mmol) were added sequentially. Then, 10 mL of toluene was added to dissolve the starting materials, yielding a bright yellow solution. The solution was stirred at 85 °C for 17 hours. After the reaction was complete, the solution was cooled to room temperature, and 10 mL of water was added and stirred for 5 minutes. The mixture was then separated, and the aqueous phase was extracted with diethyl ether (3 × 10 mL). The combined organic phases were dried over anhydrous magnesium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was further purified by silica gel column chromatography to give 3.1 g (9.1 mmol, 91.2%) of a white solid. The above-mentioned white solid product and tetrahydrofuran (20 mL) were added to a dry, nitrogen-filled 50 mL Schlenk tube. The solution was then cooled to -78 °C, and n-butyllithium (4.0 mL, 2.5 M hexane solution, 10.0 mmol) was added dropwise. The mixture was reacted at this temperature for 1 hour. Subsequently, diphenylphosphine chloride (10.0 mmol) was added dropwise. After the addition was complete, the mixture was brought to room temperature and reacted for 3 hours. After the reaction was completed, 10 mL of water was added to quench the reaction. The mixture was then further separated, extracted with diethyl ether, dried, filtered, evaporated to dryness, and purified by silica gel column chromatography to obtain the white solid product L. 10 (2.8g, 68.3%).

[0115]

[0116] (2) Preparation of complex 10

[0117] In a dry Schlenk reaction tube filled with argon, ligand L was added. 10 (223.1 mg, 0.5 mmol) and CrCl3(THF)3 (187.3 mg, 0.5 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 287.6 mg (0.43 mmol, 85.2%) of blue powder.

[0118] Example 11

[0119] The preparation of complex 11 is carried out in the following steps:

[0120] (1) Ligand L 11 Preparation

[0121] In a dry, nitrogen-filled 50 mL Schlenk tube, o-bromoiodobenzene (2.83 g, 10.0 mmol), diphenylphosphine (1.86 g, 10.0 mmol), Pd(PPh3)4 (58 mg, 0.05 mmol), and triethylamine (1.11 g, 11.0 mmol) were added sequentially. Then, 10 mL of toluene was added to dissolve the starting materials, yielding a bright yellow solution. The solution was stirred at 85 °C for 17 hours. After the reaction was complete, the solution was cooled to room temperature, and 10 mL of water was added and stirred for 5 minutes. The mixture was then separated, and the aqueous phase was extracted with diethyl ether (3 × 10 mL). The combined organic phases were dried over anhydrous magnesium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was further purified by silica gel column chromatography to give 3.1 g (9.1 mmol, 91.2%) of a white solid. The above-mentioned white solid product and tetrahydrofuran (20 mL) were added to a dry, nitrogen-filled 50 mL Schlenk tube. The solution was then cooled to -78 °C, and n-butyllithium (4.0 mL, 2.5 M hexane solution, 10.0 mmol) was added dropwise. The mixture was reacted at this temperature for 1 hour. Then, diethylphosphorus chloride (10.0 mmol) was added dropwise. After the addition was complete, the mixture was brought to room temperature and reacted for 3 hours. After the reaction was complete, 10 mL of water was added to quench the reaction. The mixture was then further separated, extracted with diethyl ether, dried, filtered, evaporated to dryness, and purified by silica gel column chromatography to obtain the white solid product L. 11 (2.6g, 80.5%).

[0122]

[0123] (2) Preparation of complex 11

[0124] In a dry Schlenk reaction tube filled with argon, ligand L was added.11 (175.1 mg, 0.5 mmol) and CrCl3(THF)3 (187.3 mg, 0.5 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 261.4 mg (0.45 mmol, 90.3%) of blue powder.

[0125] Example 12

[0126] The preparation of complex 12 is carried out in the following steps:

[0127] (1) Ligand L 12 Preparation

[0128] Reference ligand L 11 The preparation method uses (Ph)(Et)PCl (10.0 mmol) instead of diethylphosphorus chloride to obtain a white solid product L. 12 (2.3g, 62.5%). 1 H NMR (400MHz, CDCl3) δ0.86-1.04(m,3H),1.37-1.52(m,2H),7.13-7.19(m,8H),7.40-7.51(m,11H).

[0129]

[0130] (2) Preparation of complex 12

[0131] In a dry Schlenk reaction tube filled with argon, ligand L was added. 12 (199.1 mg, 0.5 mmol) and CrCl3(THF)3 (187.3 mg, 0.5 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 259.0 mg (0.41 mmol, 82.6%) of blue powder.

[0132] Example 13

[0133] The preparation of complex 13 is carried out in the following steps:

[0134] (1) Preparation of (2-F-Ph)(Ph)PH

[0135] (2-F-Ph)(Ph)PCl (2.4 g, 10 mmol) was added dropwise to a solution of lithium aluminum hydride (152.0 mg, 4 mmol) in ether (15 mL) at -78 °C and stirred for 30 minutes. The mixture was then heated to room temperature and stirred overnight. The solvent was removed from the mixture, and then hexane (10 mL) and ether (3 mL) were added to dissolve it. The mixture was filtered, and the filtrate was dried under reduced pressure to obtain an oily crude product, which was used directly in the next step.

[0136] (2) Ligand L 13 Preparation

[0137] Reference ligand L 11 The preparation method uses (2-F-Ph)(Ph)PH (10.0 mmol) instead of diphenylphosphine to obtain a white solid product L. 13 (2.6g, 70.6%). 1 H NMR (400MHz, CDCl3) δ0.86-1.04(m,6H),1.37-1.72(m,4H),7.11-7.28(m,7H),7.41-7.50(m,5H),7.62-7.71(m,1H).

[0138]

[0139] (3) Preparation of complex 13

[0140] In a dry Schlenk reaction tube filled with argon, ligand L was added. 13 (184.1 mg, 0.5 mmol) and CrCl3(THF)3 (187.3 mg, 0.5 mmol) were added, and redistilled toluene (10 mL) was added. The mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the mixture was filtered through anhydrous and oxygen-free filter. The solid obtained was washed with n-hexane (5 mL × 3) and dried under vacuum to give 254.6 mg (0.43 mmol, 85.3%) of blue powder.

[0141] Example 14

[0142] A catalyst for selective tetraphosphine ligand-containing ethylene tetramerization, its preparation method, and its application are described below:

[0143] (1) Preparation of catalyst

[0144] In a dry Schlenk reaction tube filled with argon, complex 1 (1.08 mg, 0.8 μmol) and anhydrous methylcyclohexane (20 ml) were added. After stirring for 5 minutes, modified methylaluminoxane MMAO-3A (0.4 mmol, 1.12 mol / L) was added. The mixture was reacted at room temperature for 5 minutes and then set aside for later use.

[0145] (2) Ethylene oligomerization

[0146] A 350 mL stainless steel high-pressure gas reactor was evacuated to a vacuum in an oil bath at 120 °C for 3 hours to ensure an anhydrous and oxygen-free environment. It was then cooled to the reaction temperature, and the reactor was purged three times with ethylene gas. Immediately afterward, the prepared catalyst solution was injected into the high-pressure reactor using a dry glass syringe. The reactor was sealed, stirring was started, and ethylene gas was introduced, adjusting the pressure to 500 psig. The reactor was stirred at 60 °C for 30 minutes. After the reaction, the ethylene gas supply valve was closed, the reactor was cooled to 0 °C, the pressure was released, the reactor was opened, and a quantitative amount of nonane (internal standard) was added and stirred until homogeneous. The reaction was then quenched with approximately 30 mL of 10 wt% HCl aqueous solution. A small amount of the organic phase was filtered and subjected to GC analysis. The remaining mixture in the reactor was filtered, and the solid was collected. The solid was added to a 10 wt% HCl aqueous solution and stirred for 2 hours. After filtration, the solid was dried to constant weight and weighed. The data are shown in Table 1.

[0147] Example 15

[0148] The difference from Example 14 is that complex 1 was replaced with complex 2 (1.05 mg, 0.8 μmol), and the data are shown in Table 1.

[0149] Example 16

[0150] The difference from Example 14 is that complex 1 was replaced with complex 3 (0.86 mg, 0.8 μmol), and the data are shown in Table 1.

[0151] Example 17

[0152] The difference from Example 14 is that complex 1 was replaced with complex 4 (0.94 mg, 0.8 μmol), and the data are shown in Table 1.

[0153] Example 18

[0154] The difference from Example 14 is that complex 1 was replaced with complex 5 (0.86 mg, 0.8 μmol), and the data are shown in Table 1.

[0155] Example 19

[0156] The difference from Example 14 is that complex 1 was replaced with complex 6 (0.89 mg, 0.8 μmol), and the data are shown in Table 1.

[0157] Example 20

[0158] The difference from Example 14 is that complex 1 was replaced with complex 7 (0.92 mg, 0.8 μmol), and the data are shown in Table 1.

[0159] Example 21

[0160] The difference from Example 14 is that complex 1 was replaced with complex 8 (0.97 mg, 0.8 μmol), and the data are shown in Table 1.

[0161] Example 22

[0162] The difference from Example 19 is that the ethylene oligomerization reaction was carried out at 40°C, and the data are shown in Table 1.

[0163] Example 23

[0164] The difference from Example 19 is that the ethylene oligomerization reaction was carried out at 80°C, and the data are shown in Table 1.

[0165] Example 24

[0166] The difference from Example 19 is that the amount of MMAO-3A used is 0.32 mmol, and the data is shown in Table 1.

[0167] Example 25

[0168] The difference from Example 19 is that the amount of MMAO-3A used is 0.48 mmol, and the data is shown in Table 1.

[0169] Example 26

[0170] The difference from Example 19 is that the reaction pressure for ethylene oligomerization is 400 psig, as shown in Table 1.

[0171] Example 27

[0172] The difference from Example 19 is that the reaction pressure for ethylene oligomerization is 300 psig, as shown in Table 1.

[0173] Comparative Example 1

[0174] The difference from Example 14 is that complex 1 was replaced with complex 9 (1.02 mg, 0.8 μmol), and the data are shown in Table 1.

[0175] Comparative Example 2

[0176] The difference from Example 14 is that complex 1 was replaced with complex 10 (0.54 mg, 0.8 μmol), and the amount of MMAO-3A was 0.4 mmol. The data are shown in Table 1.

[0177] Comparative Example 3

[0178] The difference from Example 14 is that complex 1 was replaced with complex 10 (0.54 mg, 0.8 μmol), and the amount of MMAO-3A was 0.2 mmol. The data are shown in Table 1.

[0179] Comparative Example 4

[0180] The difference from Example 14 is that complex 1 was replaced with complex 11 (0.46 mg, 0.8 μmol), and the amount of MMAO-3A was 0.2 mmol. The data are shown in Table 1.

[0181] Comparative Example 5

[0182] The difference from Example 14 is that complex 1 was replaced with complex 12 (0.50 mg, 0.8 μmol), and the amount of MMAO-3A was 0.2 mmol. The data are shown in Table 1.

[0183] Comparative Example 6

[0184] The difference from Example 14 is that complex 1 was replaced with complex 13 (0.48 mg, 0.8 μmol), and the amount of MMAO-3A was 0.2 mmol. The data are shown in Table 1.

[0185] Table 1

[0186]

[0187]

[0188] As can be seen from Table 1, the catalyst provided by this invention has high catalytic activity and selectivity, among which ligand L... 6 The catalytic performance is good, with an activity reaching 4370 kg / g Cr / h, and a 1-octene selectivity of 74.8%, while the total selectivity for 1-hexene and 1-octene reaches 95.8%. Comparisons of Comparative Examples 1 and 3, 15 and 4, 16 and 5, and 18 and 6 show that the phenyl-bridged tetraphosphine ligand provided by this invention exhibits significantly higher activity than the phenyl-bridged bisphosphine ligand, while also reducing the solid polymer content. Comparisons of Comparative Examples 1, 2, and 3 show that the ligand provided by this invention requires less co-catalyst, achieving higher activity with lower co-catalyst dosage.

[0189] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A catalyst for the selective tetramerization of ethylene containing a tetraphosphine ligand, characterized in that, The catalyst comprises a ligand, a transition metal compound, and an activator, wherein the chemical structural formula of the ligand is shown in formula (I) below: ， In the formula, groups R1 and R2 are each independently selected from hydrogen, halogen, or alkyl; Groups R3 to R 10 Each group is independently selected from alkyl, cycloalkyl, alkenyl, or aromatic groups, and the groups R3 to R4 are... 10 At least one of them is not phenyl.

2. The catalyst for selective tetrapolymerization of ethylene containing a tetraphosphine ligand according to claim 1, characterized in that, The alkyl group includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, cyclopentyl, n-hexyl, sec-hexyl, isohexyl, cyclohexyl, n-heptyl, cycloheptyl, n-octyl, n-decyl, 2-methylcyclopentyl, or 2,6-dimethylcyclohexyl.

3. The catalyst for selective tetrapolymerization of ethylene containing a tetraphosphine ligand according to claim 1, characterized in that, The alkenyl group includes vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-2-butenyl, 2-methyl-1-butenyl, 3-methyl-2-butenyl, 5-hexenyl, 2-cyclohexenyl, 3-cyclohexenyl, or 2-methyl-2-cyclohexenyl; the halogen is fluorine, chlorine, bromine, or iodine.

4. The catalyst for selective tetrapolymerization of ethylene containing a tetraphosphine ligand according to claim 1, characterized in that, The aromatic groups include phenyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, 2,6-difluorophenyl, 2,5-difluorophenyl, 2,4-difluorophenyl, 2,3-difluorophenyl, 3,4-difluorophenyl, 3,5-difluorophenyl, 2,6-dichlorophenyl, 2,5-dichlorophenyl, 2,4-dichlorophenyl, 2,3-dichlorophenyl, 3,4-dichlorophenyl, 3,5-dichlorophenyl, p-ethylphenyl, o-ethylphenyl, m-ethylphenyl, etc. 2,4-Dimethylphenyl, 2,4-Diisopropylphenyl, 2,4-Di-tert-butylphenyl, 2,6-Dimethylphenyl, 2,6-Diisopropylphenyl, 3,5-Dimethylphenyl, 3,5-Di-tert-butylphenyl, 2,4,6-Trimethylphenyl, Naphthyl, Anthrayl, Biphenyl, 7-Fluoro-1-naphthyl, 8-Fluoro-1-naphthyl, 7-Chloro-1-naphthyl, 8-Chloro-1-naphthyl, 9-Fluoro-1-anthrayl, 9-Chloro-1-anthrayl, 8-Fluoro-1-anthrayl, or 8-Chloro-1-anthrayl.

5. The catalyst for selective tetrapolymerization of ethylene containing a tetraphosphine ligand according to claim 1, characterized in that, The transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, or palladium; the activator includes alkylaluminum compounds, aluminum oxane compounds, or organoboron compounds; the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100):1; the molar ratio of the activator to the transition metal element in the transition metal compound is (1-10000):

1.

6. The catalyst for selective tetrapolymerization of ethylene containing a tetraphosphine ligand according to claim 5, characterized in that, The aluminum oxane compound specifically includes modified methylaluminoxane MMAO-3A; the molar ratio of the activator to the transition metal element in the transition metal compound is (250-500):

1.

7. A method for preparing a catalyst for selective tetraphosphine ligand-containing ethylene tetramerization as described in any one of claims 1-6, characterized in that, The method involves pre-mixing or directly adding ligands, transition metal compounds, and activators into the reaction system for in-situ synthesis, thereby obtaining a catalyst for the selective tetramerization of ethylene containing tetraphosphine ligands.

8. The application of a catalyst for the selective tetrapolymerization of ethylene containing a tetraphosphine ligand as described in any one of claims 1-6, characterized in that, This catalyst is used for the selective tetramerization of ethylene to produce 1-octene. The reaction is carried out in an inert solvent at a temperature of 0-200℃ and a pressure of 10-5000 psig. The concentration of the transition metal in the transition metal compound in the inert solvent is 0.01-10000 μmol / L. The inert solvent includes one or more of alkanes, aromatics, alkenes, or ionic liquids.

9. The application of the catalyst for selective tetraphosphine-containing ethylene tetramerization according to claim 8, characterized in that, The reaction temperature is 40-80℃; the pressure is 300-500 psig.

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