Chromium-nickel bimetallic center complex catalyst, its preparation method and application

Abstract

The application belongs to the technical field of coordination complex catalysts, and particularly relates to a chromium-nickel bimetallic center complex catalyst and a preparation method and application thereof. Isopropylamine, a cyclohexyl benzyl chlorophosphine and an acid binding agent are added into a solvent to react, and a PNP ligand is obtained; the PNP ligand, acetylacetone chromium and acetylacetone nickel are respectively dissolved in a solvent to obtain a PNP ligand solution, an acetylacetone chromium solution and an acetylacetone nickel solution, and the PNP ligand solution, the acetylacetone chromium solution and the acetylacetone nickel solution are mixed and stirred to react, and a chromium-nickel bimetallic center complex catalyst is obtained. The chromium-nickel bimetallic center complex catalyst prepared by the application can be used for ethylene oligomerization reaction, can quickly activate ethylene molecules and accurately control the chain growth process, and meets the dual demands of high activity and high selectivity of the catalyst for industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coordination complex catalysts, and particularly relates to a chromium-nickel bimetallic center complex catalyst, a preparation method and application thereof. BACKGROUND

[0002] Linear alpha-olefins (LAOs) are straight-chain olefin molecules with a double bond at the head. Due to the relatively active double bond structure, they become important raw materials in the petroleum and chemical industry and are widely used in polymerization and hydrogenation fields, and play an important role in the synthesis of polyethylene, lubricants, plasticizers, alcohols and surfactants. Among them, 1-octene is an important organic synthesis raw material and is widely used. In recent years, the demand for polyolefin elastomer (POE) and linear low-density polyethylene (LLDPE) and other materials has increased significantly, which has led to a sustained increase in demand for 1-octene. Therefore, 1-octene has a very broad market prospect.

[0003] The industry often uses ethylene oligomerization to prepare 1-octene. This method uses a specific catalyst (such as an alkyl aluminum plus a post-transition metal catalyst such as chromium) to perform a homogeneous reaction of selective tetramerization of ethylene in an organic solution to prepare 1-octene. Compared with the traditional method of obtaining 1-octene, the method of preparing 1-octene by ethylene oligomerization has the advantages of high selectivity, low energy consumption and simple operation. Therefore, preparing a catalyst with high reaction activity and good selectivity for 1-octene is the key to the homogeneous preparation of 1-octene by ethylene oligomerization. However, it is often difficult to find a metal homogeneous catalyst with both high catalytic activity and high 1-octene selectivity in the prior art.

[0004] Chinese patent CN119346177A discloses a high-selectivity catalyst, a preparation method and an application in an ethylene oligomerization reaction. The catalyst system includes a phosphine-containing ligand, a transition metal compound, an organic solvent and a cocatalyst. The structural formula of the phosphine-containing ligand is as follows:

[0005] ,

[0006] In the formula, n is an integer in the range of 2-10; R1, R2 and R3 are each independently selected from one or a combination of several of C2-C9 alkyl, aryl, substituted alkyl and substituted aryl. The patent has high selectivity for preparing 1-octene, but the catalytic activity is relatively low. Chinese patent CN117504934A discloses a novel chromium-based catalyst and a preparation method. The preparation of the catalyst is divided into three steps: preparation of dispersion liquid A, preparation of ligand and polymerization reaction. The solvent of the dispersion liquid A is dichloromethane, the storage temperature is -10-10℃, and the vacuum time of the reaction kettle used for the polymerization reaction is 1-3h. Although the catalyst in the patent has high activity, it has poor ability in terms of selectivity for preparing 1-octene. SUMMARY

[0007] The present application aims to provide a chromium-nickel bimetallic center complex catalyst to solve the problem of poor selectivity of 1-octene and poor reaction activity of the existing catalyst in ethylene oligomerization; and simultaneously provide a preparation method and application of the chromium-nickel bimetallic center complex catalyst.

[0008] The structural formula of the chromium-nickel bimetallic center complex catalyst is as follows:

[0009] ,

[0010] In the formula, R 1 is acetylacetone chromium, and R 2 is acetylacetone nickel.

[0011] The preparation method of the chromium-nickel bimetallic center complex catalyst comprises the following steps:

[0012] (1) isopropylamine, cyclohexyl phenyl chlorophosphine and an acid binding agent are added into a solvent to react, so as to obtain a PNP ligand;

[0013] (2) the PNP ligand, acetylacetone chromium and acetylacetone nickel are respectively dissolved in a solvent to obtain a PNP ligand solution, an acetylacetone chromium solution and an acetylacetone nickel solution; the PNP ligand solution, the acetylacetone chromium solution and the acetylacetone nickel solution are mixed and stirred to react, so as to obtain the chromium-nickel bimetallic center complex catalyst.

[0014] In step (1), the acid binding agent is triethylamine, the molar ratio of isopropylamine to the acid binding agent is 1:10-20, the solvent is dichloromethane or trichloromethane, the molar ratio of isopropylamine to the solvent is 1:123-156, and the molar ratio of isopropylamine to cyclohexyl phenyl chlorophosphine is 0.4-0.6:1.

[0015] In step (1), the reaction time is 14-15 hours, and the reaction temperature is 0-30°C.

[0016] In step (1), the structural formula of cyclohexyl phenyl chlorophosphine is as follows:

[0017] .

[0018] In step (1), the cyclohexyl phenyl chlorophosphine is prepared from diphenyl chlorophosphine.

[0019] In step (1), the reaction equation for preparing the PNP ligand is as follows:

[0020] .

[0021] In step (2), the reaction equation for preparing the chromium-nickel bimetallic center complex catalyst is as follows:

[0022] .

[0023] The molar ratio of acetylacetone chromium and acetylacetone nickel in step (2) is 8-16:1, and the molar ratio of the PNP ligand to the total moles of acetylacetone chromium and acetylacetone nickel is 1:1.5-4.5.

[0024] The molar ratio of the solvent to acetylacetone chromium in step (2) is 29-100:1, preferably 40-60:1; the reaction temperature is room temperature, and the reaction time is 1-2 hours.

[0025] The solvent in step (2) is at least one of benzene, toluene, chlorobenzene or xylene.

[0026] The application of the chromium-nickel bimetallic center complex catalyst described in the application is that the chromium-nickel bimetallic center complex catalyst, ethylene and a co-catalyst are added into a solvent to carry out oligomerization reaction to obtain 1-octene.

[0027] The co-catalyst is at least one of methylaluminoxane, modified methylaluminoxane, triethylaluminum or triisobutylaluminum, and the solvent is at least one of cyclohexane, 1,4-dioxane, cyclooctane, methylcyclohexane or toluene.

[0028] The molar ratio of the co-catalyst to the chromium-nickel bimetallic center complex catalyst is 450-600:1, and the molar ratio of the chromium-nickel bimetallic center complex catalyst to the solvent is 1:487-1000.

[0029] The oligomerization reaction temperature is 30-60°C, preferably 35-50°C, the oligomerization reaction pressure is 30-50 atm, and the oligomerization reaction time is 30-50 min.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] (1) By co-coordinating Cr and Ni bimetallic atoms to the organic phosphine ligand, a coordination mode with symmetry is formed, which brings multiple-dimensional performance improvement: the electron cloud density inside the ligand is more uniform, significantly enhancing the reaction stability; the ethylene molecule capture and ring formation rate is accelerated, improving the catalytic activity; the electronic transfer energy barrier is reduced, promoting the generation of long carbon chain products, improving the 1-octene selectivity and reducing the by-products. Compared with the traditional PNP ligand, one benzene ring connected to the P atom is replaced by cyclohexane. Because of the flexible aliphatic structure of cyclohexane compared with the rigid benzene ring, the spatial conformation can be more flexible, reducing the spatial hindrance to ethylene molecule combination. At the same time, the saturated structure of cyclohexane more stably regulates the electron density of the P atom through the sigma bond induction effect, forming a more coordinated coordination environment with the Cr and Ni bimetallic center, further amplifying the performance advantages brought by the structural design.

[0032] (2) The chromium-nickel bimetallic center complex catalyst prepared by the application can be applied to ethylene oligomerization, and the catalytic activity (oligomerization activity >=1.6*10 7 g·mol -1 (Cat)·h -1 ) and the selectivity of 1-octene (>=80%) are verified by experiments. The synergistic effect of the bimetal and the optimization of the ligand structure guarantee high catalytic efficiency, which can quickly activate ethylene molecules and accurately control the chain growth process, meeting the dual demands of high activity and high selectivity of the catalyst for industrial production.

[0033] (3) The introduction of Ni metal can promote ethylene insertion growth, terminate chain growth in time through beta-H elimination, reduce the generation of high molecular weight polymers, reduce the dosage of toxic metal Cr, significantly reduce the toxicity of the system, improve the production safety, prolong the service life of the catalyst, reduce the loss caused by frequent replacement of the catalyst, and further compress the industrialization cost, realize the balance of environmental protection and economy.

[0034] (4) The catalyst preparation process does not require complex equipment and harsh conditions, and is simple and easy to operate; the raw materials are widely available and easy to obtain, especially after replacing part of the benzene ring in the ligand with cyclohexane, the synthesis complexity of benzene ring derivatives is avoided, and the availability of raw materials is further improved. Benefiting from the optimized reaction path and stable molecular structure, the yield of the catalyst is >=90%, which provides a solid foundation for large-scale industrial production and has significant technical transformation advantages.

[0035] (5) Mechanism: The electronic configuration (3d 8 4s 2 ) of nickel makes it more accurate and rapid in the specific ethylene insertion area (C4-C6) and reaction rate compared with other metals such as Cr after being combined with phosphine ligand, so the introduction of Ni atom makes the chromium-nickel bimetallic center complex catalyst more accurate and rapid in capturing two ethylene molecules to form a metal five-membered ring structure compared with the traditional chromium metal catalyst, the metal five-membered ring structure then transfers the captured two ethylene molecules to the Cr on the ligand through H transfer, and finally the Cr metal center captures two ethylene molecules to form a metal nine-membered ring, releases 1-octene after H transfer removal, and because the introduction of Ni occupies the steric hindrance, the further capture of Cr to generate higher carbon number is inhibited. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is the nuclear magnetic resonance spectrum of the PNP ligand in Example 1.

[0037] Figure 2 Electrospray ionization mass spectrum of the chromium-nickel bimetallic center complex catalyst in Example 1.

[0038] Figure 3 Gas chromatogram of the reaction solution containing 1-octene in Example 1, where a is 1-hexene, b is cyclohexane, c is toluene, and d is 1-octene. DETAILED DESCRIPTION

[0039] The application is further described below in conjunction with examples.

[0040] Example 1

[0041] Preparation of PNP ligand:

[0042] In a glove box filled with nitrogen, 50 mL of dichloromethane, 2.26 g of cyclohexyl phenyl phosphine chloride, and 10 mL of triethylamine were sequentially added to a three-necked vacuum reaction flask, and stirred for 15 min to allow them to mix thoroughly. Then, 0.43 mL of isopropylamine was slowly added under ice-bath cooling, and stirred for 30 min, and then continued to be stirred at room temperature for 14 h. After the reaction was completed, the precipitated amine salt was removed by negative pressure filtration, and dichloromethane was removed by distillation under reduced pressure at 50°C. Subsequently, ethanol was added at 80°C to completely dissolve the precipitate, which was then transferred to an ice bath to crystallize for 1 h to precipitate white solids. The white solids were collected by filtration and washed with ether three times, and then placed in a 60°C oven to dry for 8 h. Finally, the PNP ligand was obtained with a calculated yield of 90.5%.

[0043] The yield calculation is: yield = actual moles of product / moles of isopropylamine x 100%.

[0044] The PNP ligand was characterized with CDCl3 as the solvent and TMS as the internal standard. 1 H-NMR (400 MHz, CDCl3): δ 0.974-1.062 (m, 2 H), 1.302-1.565 (m, 22 H), 3.591-3.739 (q, 1 H), 7.118-7.378 (m, 10 H). 13 C-NMR (101 MHz, CDCl3): δ 24.42, 26.05, 27.78, 28.62, 37.76, 51.92, 128.25, 130.64, 132.91, 140.01. The nuclear magnetic resonance spectrum of the PNP ligand is shown in Figure 1 , 31 P-NMR (162 MHz, CDCl3): δ 91.57.

[0045] Preparation of chromium-nickel bimetallic center complex catalyst:

[0046] The PNP ligand 4.092 mmol, acetylacetone chromium 7.44 mmol and acetylacetone nickel 0.744 mmol were respectively dissolved in toluene to obtain a PNP ligand solution, an acetylacetone chromium solution and an acetylacetone nickel solution, and the total mass of toluene was 32 g; the PNP ligand solution, the acetylacetone chromium solution and the acetylacetone nickel solution were mixed and stirred at room temperature for 1 h to obtain an orange solution, which was a chromium-nickel bimetallic center complex catalyst. The electrospray ionization mass spectrum of the chromium-nickel bimetallic center complex catalyst is shown in Figure 2 .

[0047] Preparation of 1-octene:

[0048] In a glove box, 4.092 mmol of the chromium-nickel bimetallic center complex catalyst was loaded into a 2L kettle reactor by using a syringe, vacuumized, and replaced with nitrogen and ethylene gas for 3 times respectively; then the methylaluminoxane and 168 g of cyclohexane measured in the glove box were sequentially added into the reactor, and the molar ratio of the methylaluminoxane to the chromium-nickel bimetallic center complex catalyst was 600:1; under the conditions of an oligomerization temperature of 45℃ and an oligomerization pressure of 40 atm, mechanical stirring was performed for 30 min to obtain a reaction liquid containing 1-octene. The gas chromatogram of the reaction liquid containing 1-octene is shown in Figure 3 . The oligomerization activity of the chromium-nickel bimetallic center complex catalyst was 1.66×10 7 g·mol -1 (Cat)·h -1 , and the 1-octene selectivity was 82.8%.

[0049] Example 2

[0050] Preparation of PNP ligand:

[0051] In a nitrogen-filled glove box, 53 mL of dichloromethane, 2.26 g of cyclohexyl phenyl phosphine chloride and 16 mL of triethylamine were sequentially added into a three-necked vacuum reaction bottle, and stirred for 15 min to make them fully mixed; then 0.5 mL of isopropylamine was slowly added under ice bath, stirred for 30 min, and continued to be stirred at room temperature for 14 h; after the reaction was completed, the precipitated amine salt was removed by negative pressure filtration, dichloromethane was removed by distillation under reduced pressure at 50℃, then ethanol was added at 80℃ to fully dissolve the precipitate, and then transferred to an ice bath to crystallize for 1 h to precipitate white solids. The white solids were collected by filtration and washed with ether three times, and then placed in a 60℃ oven to dry for 8 h. Finally, the PNP ligand was obtained, and the calculated yield was 90.7%.

[0052] The yield calculation formula is: yield = actual moles of product / moles of isopropylamine × 100%.

[0053] The preparation of the chromium-nickel bimetallic center complex catalyst was the same as that in Example 1.

[0054] Preparation of 1-octene:

[0055] In the glove box, 4.092 mmol of the chromium-nickel bimetallic center complex catalyst was loaded into a 2L kettle reactor by using a syringe, vacuumed, and replaced with nitrogen and ethylene gas for 3 times, respectively; then the methylaluminoxane and 400 g of cyclooctane measured in the glove box were sequentially added into the reactor, and the molar ratio of methylaluminoxane to the chromium-nickel bimetallic center complex catalyst was 450:1; under the conditions of oligomerization temperature of 60°C and oligomerization pressure of 50 atm, mechanical stirring was carried out for 50 min to obtain a reaction liquid containing 1-octene. The oligomerization activity of the chromium-nickel bimetallic center complex catalyst was 1.65x10 7 g·mol -1 (Cat)·h -1 , and the 1-octene selectivity was 81.6%.

[0056] Example 3

[0057] Preparation of PNP ligand:

[0058] In the nitrogen-filled glove box, 40 mL of dichloromethane, 2.26 g of cyclohexyl phenyl phosphine chloride and 6 mL of triethylamine were sequentially added into a three-necked vacuum reaction bottle, and stirred for 15 min to make them fully mixed; then 0.35 mL of isopropylamine was slowly added under ice bath, stirred for 30 min, and continued to be stirred at room temperature for 14 h; after the reaction was completed, the precipitated amine salt was removed by negative pressure filtration, dichloromethane was removed by distillation under reduced pressure at 50°C, then ethanol was added at 80°C to completely dissolve the precipitate, and then transferred to an ice bath to crystallize for 1 h to precipitate white solids. The white solids were collected by filtration and washed with ether three times, then placed in a 60°C oven to dry for 8 h, and finally the PNP ligand was obtained with a calculated yield of 90.4%.

[0059] The yield calculation formula is: yield = actual moles of product / moles of isopropylamine x 100%.

[0060] The preparation of the chromium-nickel bimetallic center complex catalyst was the same as that in Example 1.

[0061] Preparation of 1-octene:

[0062] In the glove box, 4.092 mmol of the chromium-nickel bimetallic center complex catalyst was loaded into a 2L kettle reactor by using a syringe, vacuumed, and replaced with nitrogen and ethylene gas for 3 times, respectively; then the methylaluminoxane and 360.5 g of 1,4-dioxane measured in the glove box were sequentially added into the reactor, and the molar ratio of methylaluminoxane to the chromium-nickel bimetallic center complex catalyst was 500:1; under the conditions of oligomerization temperature of 30°C and oligomerization pressure of 30 atm, mechanical stirring was carried out for 50 min to obtain a reaction liquid containing 1-octene. The oligomerization activity of the chromium-nickel bimetallic center complex catalyst was 1.6x107 g·mol -1 (Cat)·h -1 , 1-octene selectivity was 81.2%.

[0063] Example 4

[0064] The PNP ligand was prepared in the same manner as in Example 1.

[0065] Preparation of the chromium-nickel bimetallic center complex catalyst:

[0066] The PNP ligand 5.58 mmol, acetylacetone chromium 7.44 mmol and acetylacetone nickel 0.93 mmol were respectively dissolved in benzene to obtain a PNP ligand solution, an acetylacetone chromium solution and an acetylacetone nickel solution, and the total mass of benzene was 17.4 g; the PNP ligand solution, the acetylacetone chromium solution and the acetylacetone nickel solution were mixed and stirred at room temperature for 2 h to obtain an orange solution, which was the chromium-nickel bimetallic center complex catalyst.

[0067] Preparation of 1-octene:

[0068] 261 g of 1,4-dioxane was used instead of 168 g of cyclohexane, and the rest of the operations were the same as in Example 1. The oligomerization activity of the chromium-nickel bimetallic center complex catalyst was 1.65 x 10 7 g·mol -1 (Cat)·h -1 , 1-octene selectivity was 80.6%.

[0069] Example 5

[0070] The PNP ligand was prepared in the same manner as in Example 1.

[0071] Preparation of the chromium-nickel bimetallic center complex catalyst:

[0072] The PNP ligand 3.162 mmol, acetylacetone chromium 7.44 mmol and acetylacetone nickel 0.465 mmol were respectively dissolved in xylene to obtain a PNP ligand solution, an acetylacetone chromium solution and an acetylacetone nickel solution, and the total mass of xylene was 78.86 g; the PNP ligand solution, the acetylacetone chromium solution and the acetylacetone nickel solution were mixed and stirred at room temperature for 1.5 h to obtain an orange solution, which was the chromium-nickel bimetallic center complex catalyst.

[0073] Preparation of 1-octene:

[0074] 394.32 g of methylcyclohexane was used instead of 168 g of cyclohexane, and the rest of the operations were the same as in Example 1. The oligomerization activity of the chromium-nickel bimetallic center complex catalyst was 1.64 x 10 7 g·mol -1 (Cat)·h-1 1-octene selectivity was 80.2%.

[0075] Example 6

[0076] Preparation of PNP ligand:

[0077] In a glove box filled with nitrogen, 50 mL of chloroform, 2.26 g of cyclohexyl phenyl phosphine chloride and 10 mL of triethylamine were sequentially added into a three-necked vacuum reaction flask, and stirred for 15 min to allow them to be fully mixed. Then, 0.43 mL of isopropylamine was slowly added under ice-bath, and stirred for 30 min, and then continued to be stirred at room temperature for 14 h. After the reaction was completed, the precipitated amine salt was removed by negative pressure filtration, and chloroform was removed by distillation under reduced pressure at 50°C. Subsequently, ethanol was added at 80°C to fully dissolve the precipitate, and then transferred into an ice-bath to crystallize for 1 h to precipitate white solids. The white solids were collected by filtration and washed with ether for three times, and then placed in a 60°C oven for drying for 8 h. Finally, the PNP ligand was obtained with a calculated yield of 88.5%.

[0078] The yield calculation formula is: yield = actual moles of product / moles of isopropylamine x 100%.

[0079] Preparation of chromium-nickel bimetallic center complex catalyst:

[0080] The PNP ligand 1.86 mmol, acetylacetone chromium 7.44 mmol and acetylacetone nickel 0.93 mmol were respectively dissolved in toluene to obtain a PNP ligand solution, an acetylacetone chromium solution and an acetylacetone nickel solution, and the total mass of toluene was 32 g. The PNP ligand solution, the acetylacetone chromium solution and the acetylacetone nickel solution were mixed and stirred at room temperature for 1 h to obtain an orange solution, which was the chromium-nickel bimetallic center complex catalyst.

[0081] Preparation of 1-octene:

[0082] In a glove box, 4.092 mmol of chromium-nickel bimetallic center complex catalyst was loaded into a 2L kettle reactor by using a syringe, and vacuumed and replaced with nitrogen and ethylene gas for three times, respectively. Then, the methylaluminoxane and 168 g of cyclohexane measured in the glove box were sequentially added into the reactor, and the molar ratio of methylaluminoxane to chromium-nickel bimetallic center complex catalyst was 600:1. The oligomerization was carried out at an oligomerization temperature of 45°C and an oligomerization pressure of 35 atm for 40 min under mechanical stirring to obtain a reaction liquid containing 1-octene. The oligomerization activity of the chromium-nickel bimetallic center complex catalyst was 1.61 x 10 7 g·mol -1 (Cat)·h -1 1-octene selectivity was 80.8%.

[0083] Comparative Example 1

[0084] The other steps are the same as in Example 1 except that no nickel acetylacetonate is added. The prepared catalyst has an oligomerization activity of 6.86 x 10 6 g-mol -1 (Cat) h -1 and a 1-octene selectivity of 72.8%.

[0085] Comparative Example 2

[0086] The other steps are the same as in Example 1 except that no chromium acetylacetonate is added. The prepared catalyst has an oligomerization activity of 5.34 x 10 3 g-mol -1 (Cat) h -1 and a 1-octene selectivity of 1.34%.

[0087] Comparative Example 3

[0088] Preparation of PNP ligand:

[0089] In a glove box filled with nitrogen, 50 mL of dichloromethane, 1.95 g of diphenyl phosphine chloride and 10 mL of triethylamine were sequentially added to a three-necked vacuum reaction flask, stirred for 15 min to allow them to mix well; then 0.43 mL of isopropylamine was slowly added under ice-bath cooling, stirred for 30 min, and then continued to stir at room temperature for 14 h; after the reaction was completed, the precipitated amine salt was removed by negative pressure filtration, dichloromethane was removed by distillation under reduced pressure at 50°C, and then ethanol was added at 80°C to completely dissolve the precipitate, which was then transferred to an ice bath to crystallize for 1 h to precipitate white solids. The white solids were collected by filtration and washed with ether three times, then placed in a 60°C oven to dry for 8 h, and finally the PNP ligand was obtained with a calculated yield of 78.5%.

[0090] The preparation of the chromium-nickel bimetallic center complex catalyst and the preparation of 1-octene were the same as in Example 1. The prepared chromium-nickel bimetallic center complex catalyst has an oligomerization activity of 8.68 g x 10 6 g-mol -1 (Cat) h -1 and a 1-octene selectivity of 72%.

Claims

1. A chromium-nickel bimetallic complex catalyst characterized in that The preparation method of the chromium-nickel bimetallic center complex catalyst comprises the following steps: (1) isopropylamine, cyclohexyl phenyl chlorophosphine and an acid binding agent are added into a solvent to react, to obtain a PNP ligand; (2) the PNP ligand, chromium acetylacetonate and nickel acetylacetonate are respectively dissolved in a solvent to obtain a PNP ligand solution, a chromium acetylacetonate solution and a nickel acetylacetonate solution, and the PNP ligand solution, the chromium acetylacetonate solution and the nickel acetylacetonate solution are mixed and stirred to react, to obtain the chromium-nickel bimetallic center complex catalyst; In step (2), the molar ratio of the chromium acetylacetonate and the nickel acetylacetonate is 8-16:1, and the molar ratio of the PNP ligand to the total moles of the chromium acetylacetonate and the nickel acetylacetonate is 1:1.5-4.5, and the structural formula of the PNP ligand is as follows: 。 2. The chromium-nickel bimetallic complex catalyst according to claim 1, characterized in that In step (1), the acid binding agent is triethylamine, the molar ratio of the isopropylamine to the acid binding agent is 1:10-20, the solvent is dichloromethane or trichloromethane, the molar ratio of the isopropylamine to the solvent is 1:123-156, and the molar ratio of the isopropylamine to the cyclohexyl phenyl chlorophosphine is 0.4-0.6:

1.

3. The chromium-nickel bimetallic complex catalyst of claim 1, wherein In step (2), the molar ratio of the solvent to the chromium acetylacetonate is 29-100:1, the reaction temperature is room temperature, and the reaction time is 1-2 hours.

4. The chromium-nickel bimetallic complex catalyst of claim 1, wherein In step (2), the solvent is at least one of benzene, toluene, chlorobenzene or xylene.

5. Use of the chromium-nickel bimetallic complex catalyst according to claim 1, characterized in that The chromium-nickel bimetallic center complex catalyst, ethylene and a co-catalyst are added into a solvent to perform an oligomerization reaction, to obtain 1-octene.

6. Use of a chromium-nickel bimetallic complex catalyst according to claim 5, characterized in that The co-catalyst is at least one of methylaluminoxane, modified methylaluminoxane, triethylaluminum or triisobutylaluminum, and the solvent is at least one of cyclohexane, 1,4-dioxane, cyclooctane, methylcyclohexane or toluene.

7. Use of a chromium-nickel bimetallic complex catalyst according to claim 5, characterized in that The molar ratio of the co-catalyst to the chromium-nickel bimetallic center complex catalyst is 450-600:1, and the molar ratio of the chromium-nickel bimetallic center complex catalyst to the solvent is 1:487-1000.

8. Use of a chromium-nickel bimetallic complex catalyst according to claim 5, characterized in that The oligomerization reaction temperature is 30-60℃, the oligomerization reaction pressure is 30-50 atm, and the oligomerization reaction time is 30-50 min.

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