Method for preparing 1-octylene through ethylene oligomerization

Abstract

The invention provides a method for preparing 1-octylene through ethylene oligomerization, ethylene is subjected to oligomerization reaction under the action of a catalyst system under anhydrous and anaerobic conditions to obtain 1-octylene, and the catalyst system comprises a transition metal compound main catalyst, a transition metal compound auxiliary catalyst, a transition metal compound main catalyst, a transition metal compound main catalyst and a transition metal compound auxiliary catalyst, the chemical formula of the organic ligand is # imgabs0 #. According to the method for preparing 1-octylene through ethylene oligomerization, the catalytic activity of a catalytic system in the process of preparing 1-octylene through ethylene oligomerization can be improved, the selectivity and yield of 1-octylene are further improved, the generation amount of oligomers can be reduced, and the continuity, stability and efficiency of the preparation process can be improved.

Description

Technical Field

[0001] The invention relates to the field of organic synthesis, in particular to a method for preparing 1-octene by polymerization of ethylene. Background Art

[0002] As an important organic raw material and chemical intermediate, 1-octene can be used to produce polyethylene and to produce plasticizers, fatty acids, detergents and lubricants. Among them, ethylene polymerization, as one of the methods for preparing 1-octene, has the advantages of high catalytic activity, high quenching efficiency and long operation cycle. However, in the process of preparing 1-octene by ethylene polymerization, by-products such as oligomers will inevitably be produced, resulting in low selectivity and yield of 1-octene. Moreover, the production of oligomers will also cause serious blockage of the reactor and its connecting pipelines in the ethylene polymerization process, so the process pipelines and reactors must be cleaned frequently, thereby destroying the continuity, stability and efficiency of the preparation process. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing 1-octene by ethylene polymerization, which can improve the catalytic activity of the catalyst system in the preparation of 1-octene by ethylene polymerization, thereby improving the selectivity and yield of 1-octene, and can also reduce the amount of oligomers generated, thereby improving the continuity, stability and efficiency of the preparation process.

[0004] To solve the above technical problems, the present invention is implemented through the following technical solutions.

[0005] The present invention provides a method for preparing 1-octene by oligomerization of ethylene. Under anhydrous and oxygen-free conditions, ethylene undergoes an oligomerization reaction under the action of a catalyst system to obtain 1-octene, wherein the catalyst system comprises:

[0006] Transition metal compound main catalyst;

[0007] Organic ligand, chemical formula as well as

[0008] Co-catalyst.

[0009] In one embodiment of the present invention, the transition metal compound main catalyst is selected from at least one of chromium isooctanoate, chromium n-octanoate, chromium chloride tetrahydrofuran complex, chromium acetate, chromium acetylacetonate or diisoprene chromium.

[0010] In one embodiment of the present invention, the co-catalyst is selected from at least one of triisobutylaluminum, triethylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, methylaluminoxane or modified methylaluminoxane.

[0011] In one embodiment of the present invention, the co-catalyst includes the triisobutylaluminum and the modified methylaluminoxane, and the molar ratio of the triisobutylaluminum to the modified methylaluminoxane is (0.1-9):1.

[0012] In one embodiment of the present invention, in the catalyst system, the molar ratio of the co-catalyst, the organic ligand and the transition metal compound main catalyst is (500-2000):(0.5-3):1.

[0013] In one embodiment of the present invention, the temperature of the polymerization reaction is 30° C. to 120° C., the reaction pressure is 2 MPa to 8 MPa, and the reaction time is 0.1 h to 1 h.

[0014] In one embodiment of the present invention, the polymerization reaction system further comprises a solvent, and the solvent is selected from at least one of isoparaffins, benzene, toluene, hexane, methylcyclohexane, n-heptane or cyclohexane.

[0015] In one embodiment of the present invention, the preparation of the organic ligand comprises at least the following steps:

[0016] Under a stable gas atmosphere, mixing dichlorophenylphosphine and a reagent uniformly to obtain a mixture;

[0017] placing the mixture in a cold source, cooling the mixture to a first temperature, adding dicyclopentylamine and mixing for a first time to obtain an intermediate product;

[0018] After taking out the intermediate product from the cold source, heating the intermediate product to a second temperature and keeping the temperature for a second time to obtain a reaction product; and

[0019] The reaction product is purified to obtain the organic ligand.

[0020] In one embodiment of the present invention, the first temperature is -5°C to 5°C, and the first time is 0.2h to 0.7h.

[0021] In one embodiment of the present invention, the second temperature is 15° C. to 40° C., and the second time is 8 h to 16 h.

[0022] In summary, the present invention provides a method for preparing 1-octene by ethylene oligomerization, which can improve the catalytic activity of the catalyst system in the preparation of 1-octene by ethylene oligomerization, thereby improving the selectivity and yield of 1-octene. The amount of oligomers generated in the preparation of 1-octene by ethylene oligomerization can be reduced, and there is no need to frequently clean the reaction equipment and pipelines in the preparation process, thereby improving the continuity, stability and efficiency of the preparation process. The preparation cost of 1-octene can be reduced, and the method is suitable for large-scale production of 1-octene.

[0023] Of course, any method of implementing the present invention does not necessarily need to achieve all of the advantages mentioned above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0025] Figure 1 It is the spectrum of the nuclear magnetic resonance hydrogen spectrum of the organic ligand in the present invention. DETAILED DESCRIPTION

[0026] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0027] It should be understood that the present invention can be implemented in different forms and should not be interpreted as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0028] The technical solution of the present invention is further described in detail below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] The present invention provides a method for preparing 1-octene by oligomerization of ethylene, wherein ethylene is subjected to oligomerization reaction under the action of a catalyst system under anhydrous and oxygen-free conditions to obtain 1-octene, wherein the ethylene oligomerization to prepare 1-octene is carried out, for example, by continuous production or intermittent production, and the present invention does not limit the production method. Specifically, the method for preparing 1-octene by oligomerization of ethylene includes at least steps S11-S14.

[0030] Step S11, dehydrating and deoxygenating the reactor.

[0031] Step S12, after the reactor is heated to the reaction temperature, ethylene, solvent and catalyst system are introduced into the reactor and mixed, so that the pressure of the reactor is maintained at the reaction pressure.

[0032] Step S13: After the ethylene stays in the reactor for the reaction time, the materials in the reactor are taken out and cooled.

[0033] Step S14, adding a terminator to the cooled material to obtain 1-octene.

[0034] In one embodiment of the present invention, in step S11, when the reactor is subjected to dehydration and deoxygenation treatment, the reactor is first heated to, for example, 100° C. to 200° C., and then the gas in the reactor is replaced with a stable gas to obtain a reactor free of water and oxygen, which is convenient for the occurrence of ethylene polymerization reaction. The stable gas includes, for example, at least one of nitrogen and an inert gas, and the number of replacements is, for example, at least 3 times. The reactor is, for example, a stirred tank reactor.

[0035] In one embodiment of the present invention, after obtaining a water-free and oxygen-free reactor, in step S12, the speed of the reactor is controlled at a preset speed, the reactor is heated to the reaction temperature, and then ethylene, solvent and catalyst system are introduced into the reactor to maintain the pressure of the reactor at the reaction pressure. Among them, the preset speed is, for example, 500r / min to 2000r / min, the reaction temperature is, for example, 30°C to 120°C, and for example, 50°C to 80°C, the reaction pressure is, for example, 2MPa to 8MPa, and for example, 3MPa to 7MPa, the reaction stress is, for example, provided and controlled by ethylene, the solvent is selected from at least one of isoparaffin, benzene, toluene, hexane, methylcyclohexane, n-heptane or cyclohexane, and the catalyst system includes, for example, a transition metal compound main catalyst, a co-catalyst and an organic ligand.

[0036] In one embodiment of the present invention, in the catalyst system of step S12, the transition metal compound main catalyst is selected from at least one of chromium isooctanoate, chromium n-octanoate, chromium chloride tetrahydrofuran complex, chromium acetate, chromium acetylacetonate or diisoprene chromium, and the concentration of the transition metal compound main catalyst in ethylene, solvent and catalyst system is, for example, 0.005 μmol / mL to 0.08 μmol / mL, and the transition metal compound main catalyst is added to the reactor in a solid or liquid state. Further, in this embodiment, the transition metal compound main catalyst is, for example, chromium acetylacetonate, and chromium acetylacetonate is added to the reactor in a liquid state to improve the uniformity of the dispersion of chromium acetylacetonate in the reactor, so that the catalyst system can better exert catalytic activity. Specifically, after the chromium acetylacetonate and the solvent are evenly mixed, a chromium acetylacetonate solution is obtained, and then the chromium acetylacetonate solution is added to the reactor. Among them, the solvent includes, for example, at least one of xylene, benzene and n-heptane.

[0037] In one embodiment of the present invention, in the catalyst system of step S12, the co-catalyst is selected from at least one of triisobutylaluminum, triethylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, methylaluminoxane or modified methylaluminoxane. Further, in this embodiment, the co-catalyst includes triisobutylaluminum and modified methylaluminoxane, and the molar ratio of triisobutylaluminum and modified methylaluminoxane is, for example, (0.1-9): 1, specifically, for example, 2: 1, 3: 1 or 4: 1. By using triisobutylaluminum and modified methylaluminoxane as co-catalysts, the production cost of 1-octene can be reduced while ensuring that the catalyst system has a high catalytic activity, which is suitable for large-scale production of 1-octene.

[0038] In one embodiment of the present invention, in the catalyst system of step S12, the chemical formula of the organic ligand is And the organic ligand is prepared, for example, according to steps S121-S124.

[0039] S121. Under a stable gas atmosphere, uniformly mix dichlorophenylphosphine and a reagent to obtain a mixture.

[0040] S122, placing the mixture in a cold source, and after the mixture is cooled to a first temperature, adding dicyclopentylamine and mixing for a first time to obtain an intermediate product.

[0041] S123. After taking out the intermediate product from the cold source, the intermediate product is heated to a second temperature and kept warm for a second time to obtain a reaction product.

[0042] S124. Purify the reaction product to obtain an organic ligand.

[0043] In one embodiment of the present invention, in step S121, the stabilizing gas includes, for example, at least one of nitrogen or an inert gas, and the reagent includes, for example, at least one of dichloromethane and triethylamine, and the volume of the reagent is, for example, 20 mL-100 mL. In the present embodiment, the reagent includes, for example, dichloromethane and triethylamine, and the volume ratio of dichloromethane and triethylamine is, for example, (3-7): 1. Among them, dichlorophenylphosphine is used as one of the reactants to react with the dicyclopentylamine added subsequently to synthesize the organic ligand. The reagent, as a reaction solvent, can make the reactant molecules more easily dissociate to form ionic intermediates, thereby promoting the reaction and accelerating the rate of preparing the organic ligand.

[0044] In one embodiment of the present invention, in step S122, the cold source is, for example, an ice bath, the first temperature is, for example, -5°C to 5°C, the first time is, for example, 0.2h to 0.7h, the dicyclopentylamine is added to the mixture by, for example, dropwise addition, and the molar ratio of dicyclopentylamine to dichlorophenyl phosphine is, for example, (2-3): 1. Adding dicyclopentylamine to the mixture by dropwise addition can facilitate the full reaction of dicyclopentylamine and dichlorophenyl phosphine in the mixture, thereby improving the yield and purity of the intermediate product.

[0045] In one embodiment of the present invention, in step S123, dicyclopentylamine and dichlorophenyl phosphine react to generate an organic ligand containing an NPN structure, wherein the second temperature is, for example, 15° C. to 40° C., the second time is, for example, 8 h to 16 h, and the reaction product includes, for example, an organic ligand, a solvent, and unreacted dicyclopentylamine and dichlorophenyl phosphine, etc. Therefore, the reaction product must be purified to improve the purity of the organic ligand containing an NPN structure.

[0046] In one embodiment of the present invention, in step S124, when the reaction product is purified, the reaction product is first filtered to obtain a filtrate, and then the filtrate is subjected to reduced pressure distillation. In the reduced pressure distillation, after the low-boiling point fraction in the filtrate is evaporated, the high-boiling point fraction is collected and taken out from the reduced pressure distillation device, and then the high-boiling point fraction is recrystallized to obtain a white granular solid, that is, an organic ligand containing an NPN structure. The pressure of the reduced pressure distillation is, for example, -0.05Mpa to -0.095Mpa, the solvent during recrystallization includes, for example, dichloromethane, and the temperature of the recrystallization is, for example, -10°C to 20°C.

[0047] In one embodiment of the present invention, after the white granular solid is obtained in step S124, for example, a nuclear magnetic resonance hydrogen spectrum analysis is performed on the solid to determine the structural formula of the white granular solid, and its spectrum is as follows: Figure 1 As shown. Figure 1 It can be seen that the white granular solid has peaks near the chemical shifts (Parts Per Million, PPM) of 7.25, 2.6, 1.6 and 1.5, thus confirming that the chemical formula of the organic ligand is:

[0048] In one embodiment of the present invention, in the catalyst system of step S12, the molar ratio of the co-catalyst, the organic ligand and the transition metal compound main catalyst is, for example, (500-2000): (0.5-3): 1, and further, for example, (800-1500): (1-2): 1. Wherein, the transition metal compound main catalyst and the co-catalyst form an active center under the action of the organic ligand, catalyze the polymerization reaction of ethylene to prepare 1-octene, improve the selectivity and yield of 1-octene, reduce the generation of by-products such as oligomers, thereby improving the continuity, stability and efficiency of the preparation process. Specifically, in this embodiment, by adding the organic ligand, the catalytic activity of the catalyst system is, for example, 2000Kg / gCr-3600Kg / gCr, the selectivity of 1-octene is, for example, 60%-80%, and the content of oligomers is, for example, 0.05wt%-0.5wt%.

[0049] In one embodiment of the present invention, after ethylene, solvent and catalyst system are introduced, in step S13, the reaction time of ethylene staying in the reactor is, for example, 0.1h-1h, and for example, 0.15h-0.5h, and the temperature is lowered, for example, by natural cooling or ice bath cooling, etc. By controlling the residence time, the selectivity and yield of 1-octene can be improved, and the generation of a large number of by-products such as oligomers can be avoided.

[0050] In one embodiment of the present invention, after the material is cooled, in step S14, a terminator is added to the material to obtain 1-octene. The terminator includes, for example, at least one of ethanol, sodium dimethyldithiocarbamate, sodium polysulfide, and sodium nitrite. By adding the terminator, ethylene can be prevented from continuing to participate in the reaction, and side reactions of ethylene can be avoided, thereby improving the yield and selectivity of 1-octene.

[0051] In one embodiment of the present invention, after obtaining 1-octene, the 1-octene may be purified to remove the terminator and solvent in the 1-octene to obtain high-purity 1-octene. The method for purifying 1-octene is, for example, distillation, extraction or crystallization, which may be selected according to actual needs.

[0052] The technical scheme of the present invention is described in detail below through several specific examples and comparative examples. Unless otherwise specified, the raw materials and reagents used in the following examples and comparative examples are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the examples can all be commercially available.

[0053] Example 1

[0054] Before the experiment, a 500 mL stirred tank reactor was replaced with vacuum high-purity nitrogen three times at a high temperature of 150°C, chromium acetylacetonate was mixed with xylene to prepare a chromium acetylacetonate solution, and triisobutylaluminum and modified methylaluminoxane were mixed in a molar ratio of 4:1 as a co-catalyst.

[0055] Under N2 protection, 0.02 mol of dichlorophenylphosphine, 50 mL of dichloromethane and 10 mL of triethylamine were added to a 100 mL three-necked round-bottom flask, stirred, cooled to 0 ° C in an ice bath, and then 0.04 mol of dicyclopentylamine was slowly added dropwise. After stirring for 30 minutes, the ice bath was removed, and the temperature was slowly raised to room temperature. The reaction was continued for 12 hours to obtain a reaction product. The reaction product was filtered, and the filtrate was subjected to reduced pressure distillation at -0.095 MPa. The high boiling point fraction was collected and the fraction was recrystallized using dichloromethane solvent to obtain an organic ligand. The heating temperature during recrystallization was 10 ° C.

[0056] The stirred tank reactor and its connecting pipes are preheated and stabilized to 60°C, and the speed of the reactor is set to 800r / min. Then ethylene is introduced into the reactor to control the pressure in the reactor at 4Mpa, and at the same time, chromium acetylacetonate solution, organic ligand and co-catalyst are added into the reactor according to a molar ratio of 500:1:1, and an appropriate amount of solvent is added to make the concentration of chromium acetylacetonate in the reaction system 0.03μmol / mL. After the residence time of the material in the reactor reaches 10min, the material is continuously taken out of the reactor and cooled in an ice bath, and an ethanol terminator is added to the material to obtain 1-octene.

[0057] Example 2

[0058] The difference between this embodiment and embodiment 1 is that the residence time of the material in the reactor is 20 minutes.

[0059] Example 3

[0060] The difference between this embodiment and embodiment 1 is that the residence time of the material in the reactor is 30 minutes.

[0061] Example 4

[0062] The difference between this embodiment and embodiment 1 is that the residence time of the material in the reactor is 60 minutes.

[0063] Example 5

[0064] The difference between this embodiment and embodiment 1 is that the stirred tank reactor and its connecting pipes are preheated and stabilized to 70° C., and the concentration of chromium acetylacetonate in the reaction system is 0.02 μmol / mL.

[0065] Example 6

[0066] The difference between this embodiment and embodiment 5 is that the residence time of the material in the reactor is 20 minutes.

[0067] Example 7

[0068] The difference between this embodiment and embodiment 5 is that the residence time of the material in the reactor is 30 minutes.

[0069] Example 8

[0070] The difference between this embodiment and embodiment 5 is that the residence time of the material in the reactor is 60 minutes.

[0071] Example 9

[0072] The difference between this embodiment and embodiment 1 is that modified methylaluminoxane is used as a co-catalyst.

[0073] Comparative Example 1

[0074] The difference between this embodiment and embodiment 1 is that the organic ligand is (P(Ph)2N(i-C3H7)P(Ph)2).

[0075] Specifically, under N2 protection, 0.02 mol of dichlorophenylphosphine, 50 mL of dichloromethane and 10 mL of triethylamine were added to a 100 mL three-necked round-bottom flask, stirred, cooled to 0°C in an ice bath, and then 0.01 mol of isopropylamine was slowly added dropwise. After stirring for 30 minutes, the ice bath was removed, and the temperature was slowly raised to room temperature. The reaction was continued for 12 hours to obtain a reaction product. The reaction product was filtered, and the filtrate was subjected to reduced pressure distillation at -0.095 MPa. The high boiling point fraction was collected and the fraction was recrystallized using a dichloromethane solvent to obtain an organic ligand P(Ph)2N(i-C3H7)P(Ph)2. The heating temperature during recrystallization was 10°C.

[0076] The reaction parameters in Examples 1-9 and Comparative Example 1 are summarized in Table 1. In addition, the 1-octene prepared in Examples 1-9 and Comparative Example 1 was subjected to gas chromatography detection and oligomer testing, and the catalyst system in Examples 1-9 and Comparative Example 1 was subjected to catalytic activity testing, and the test results are shown in Table 1.

[0077] Table 1. Reaction parameters and test data of Examples 1-9 and Comparative Example 1

[0078]

[0079] As shown in Table 1, it can be seen from the comparison of Example 3, Example 7 and Comparative Example 1 that when the catalyst system includes the organic ligand containing the NPN structure provided by the present invention, the catalytic activity and 1-octene selectivity of the catalyst system are higher, and the content of oligomers is lower. Therefore, by adding the organic ligand containing the NPN structure to the catalyst system, the catalytic activity and 1-octene selectivity of the catalyst system can be improved, and the content of oligomers can be reduced.

[0080] As shown in Table 1, by comparing Examples 1-4 and Examples 5-8, it can be seen that as the residence time of ethylene in the reactor increases, the catalytic activity of the catalyst system increases, the selectivity of 1-octene increases first and then decreases overall, and the content of oligomers decreases first and then increases overall. Therefore, by controlling the residence time of ethylene in the reactor, the selectivity of 1-octene and the content of oligomers can be changed.

[0081] As shown in Table 1, by comparing Example 1 with Example 5, Example 2 with Example 6, Example 3 with Example 7, and Example 4 with Example 8, it can be seen that as the temperature in the reactor and the concentration of chromium acetylacetonate increase, the catalytic activity of the catalyst system increases significantly. Therefore, by controlling the temperature in the reactor and the concentration of chromium acetylacetonate, the catalytic activity of the catalyst system can be changed.

[0082] As shown in Table 1, it can be seen from the comparison between Example 1 and Example 9 that, compared with the mixture of triisobutylaluminum and modified methylaluminoxane as a co-catalyst, when modified methylaluminoxane is used alone as a co-catalyst, the catalytic activity and selectivity of the catalyst system to 1-octene are higher, and the content of oligomers is lower. Therefore, by changing the type of the co-catalyst, the catalytic activity of the catalyst system, the selectivity to 1-octene, and the content of oligomers can be changed.

[0083] In summary, the present invention provides a method for preparing 1-octene by ethylene polymerization. By introducing an organic ligand containing an NPN structure into the catalyst system for preparing 1-octene by ethylene polymerization, the catalytic activity of the catalyst system can be improved, thereby improving the selectivity and yield of 1-octene. Moreover, the organic ligand provided by the present invention and its preparation method and application can reduce the amount of oligomers generated in the preparation of 1-octene by ethylene polymerization, and there is no need to frequently clean the reaction equipment and pipelines in the preparation process, thereby improving the continuity, stability and efficiency of the preparation process. At the same time, the organic ligand provided by the present invention and its preparation method and application can reduce the preparation cost of 1-octene and are suitable for large-scale production of 1-octene.

[0084] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing 1-octene by ethylene oligomerization, characterized in that: Under anhydrous and oxygen-free conditions, ethylene undergoes an oligomerization reaction under the action of a catalyst system to obtain 1-octene, wherein the catalyst system comprises: Transition metal compound main catalyst; Organic ligand, chemical formula as well as Promoter catalyst.

2. The method for preparing 1-octene by ethylene oligomerization according to claim 1, characterized in that: The transition metal compound main catalyst is selected from at least one of chromium isooctanoate, chromium n-octanoate, chromium chloride tetrahydrofuran complex, chromium acetate, chromium acetylacetonate or diisoprene chromium.

3. The method for preparing 1-octene by ethylene oligomerization according to claim 1, characterized in that: The co-catalyst is selected from at least one of triisobutylaluminum, triethylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, methylaluminoxane or modified methylaluminoxane.

4. The method for preparing 1-octene by ethylene oligomerization according to claim 3, characterized in that: The co-catalyst includes the triisobutylaluminum and the modified methylaluminoxane, and the molar ratio of the triisobutylaluminum to the modified methylaluminoxane is (0.1-9):

1.

5. The method for preparing 1-octene by ethylene oligomerization according to claim 1, characterized in that: In the catalyst system, the molar ratio of the co-catalyst, the organic ligand and the transition metal compound main catalyst is (500-2000):(0.5-3):

1.

6. The method for preparing 1-octene by ethylene oligomerization according to claim 1, characterized in that: The temperature of the polymerization reaction is 30° C. to 120° C., the reaction pressure is 2 MPa to 8 MPa, and the reaction time is 0.1 h to 1 h.

7. The method for preparing 1-octene by ethylene oligomerization according to claim 1, characterized in that: The polymerization reaction system further comprises a solvent, and the solvent is selected from at least one of isoparaffin, benzene, toluene, hexane, methylcyclohexane, n-heptane or cyclohexane.

8. The method for preparing 1-octene by ethylene oligomerization according to claim 1, characterized in that: The preparation of the organic ligand comprises at least the following steps: Under a stable gas atmosphere, mixing dichlorophenylphosphine and a reagent uniformly to obtain a mixture; placing the mixture in a cold source, cooling the mixture to a first temperature, adding dicyclopentylamine and mixing for a first time to obtain an intermediate product; After taking out the intermediate product from the cold source, heating the intermediate product to a second temperature and keeping the temperature for a second time to obtain a reaction product; as well as The reaction product is purified to obtain the organic ligand.

9. The method for preparing 1-octene by ethylene oligomerization according to claim 8, characterized in that: The first temperature is -5°C to 5°C, and the first time is 0.2h to 0.7h.

10. The method for preparing 1-octene by ethylene oligomerization according to claim 8, characterized in that: The second temperature is 15° C. to 40° C., and the second time is 8 h to 16 h.

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