High-performance polyethylene catalyst as well as preparation method and application thereof
By using inert alkane solvents and alkoxysilane modifiers in the preparation of Ziegler-Natta catalysts, the problems of difficult recovery and unstable performance caused by excessive use of titanium compounds were solved, and efficient and stable polyethylene catalyst preparation and polymerization effects were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI LEADER CATALYST
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-12
AI Technical Summary
In existing Ziegler-Natta catalyst preparation methods, the excessive use of titanium compounds leads to difficulties in recycling, environmental problems, and unstable catalyst performance. Furthermore, traditional titanium trichloride affects catalyst activity and produces undesirable sticky resins.
A stable polyethylene catalyst was prepared by using an inert alkane solvent and an alkoxysilane modifier, through the reaction of a silicon-based dispersant with alkylaluminum, alkylmagnesium, and titanium-containing compounds, thereby reducing the amount of titanium compounds used and improving the stability of the catalyst.
This approach enhances catalyst stability and activity, reduces polymerization rate, makes it suitable for long residence time reactors, and improves polymer bulk density and polymerization efficiency.
Smart Images
Figure CN122011241A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polyolefin catalyst preparation, and in particular to a high-performance polyethylene catalyst, its preparation method, and its application. Background Technology
[0002] Polyolefin materials are among the most important synthetic materials, occupying a crucial position in the national economic structure. The rapid development of the polyolefin industry is due, on the one hand, to the high quality and low price of polyolefin products, and on the other hand, to the development and advancement of highly efficient polyethylene catalysts. In 1956, German organic chemist Ziegler first discovered that the TiCl4 / Et3Al system could effectively catalyze the polymerization of ethylene under relatively low pressure. Subsequently, Italian chemist Natta developed this catalytic system for the isotactic polymerization of propylene, butadiene, isopentenene, etc. These catalysts were later known as Ziegler-Natta catalysts. With continuous progress in this type of catalyst, a large number of polyolefin products on the market are currently produced using catalysts based on this system.
[0003] Ziegler-Natta catalysts are composed of magnesium compounds, titanium compounds, and various electron donors and organoaluminum compounds. Many existing technologies require the addition of excess titanium compounds for precipitation to either extract the catalyst or increase its loading. Catalysts prepared using this method exhibit unstable performance, and the large-scale use of titanium compounds leads to recycling difficulties and environmental problems. Another existing technology uses titanium trichloride / magnesium chloride as active components supported on silica gel to prepare supported polyethylene catalysts. However, this is limited by the titanium trichloride production process. Titanium trichloride is generally obtained by reducing titanium tetrachloride with aluminum / aluminum compounds during catalyst preparation, or by using the commercially available AA titanium trichloride (TiCl3·1 / 3AlCl3). Aluminum trichloride not only affects the loading of the active components and thus the catalyst activity, but also generates undesirable sticky resins during polymerization. Summary of the Invention
[0004] The main purpose of this invention is to overcome the aforementioned problems existing in the current technology by providing a polyethylene catalyst, its preparation method, and its application.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] One of the technical solutions of the present invention is to provide a method for preparing a polyethylene catalyst, comprising the following steps:
[0007] S1. After fluidizing the silicon-based dispersant, disperse it in an inert alkane solvent and add alkyl aluminum to obtain a post-treatment dispersant;
[0008] An inert alkane solvent, alkyl magnesium, alkyl aluminum, and a monohydric alcohol are mixed to obtain a mother liquor.
[0009] S2. The mother liquor obtained in step S1 is added dropwise to the post-treatment dispersant for reaction. A titanium-containing compound is added to continue the reaction, and an alkoxysilane is added to continue the reaction to obtain a polyethylene catalyst.
[0010] In some specific embodiments, in step S1, the silicon-based dispersant in the post-treatment dispersant is selected from any one or more of silica gel, silica gel-alumina, and silica gel-titanium dioxide.
[0011] The inert alkane solvent is selected from any one or more of n-hexane, cyclohexane, hexane, and n-heptane;
[0012] The alkylaluminum is of chemical formula R. 3-n AlX n Compounds in which R is an alkyl group, X is a halogen, and n is an integer of 0 or less than 3.
[0013] In some specific embodiments, the content of SiO2 in the silicon-based dispersant is 80-100 wt%.
[0014] Preferably, the content of SiO2 in the silicon-based dispersant is 94.9-99.9 wt%.
[0015] In some specific embodiments, the silicon-based dispersant may be a porous particulate material with appropriate particle size, specific surface area, pore volume, and pore size, facilitating the dispersion and loading of the effective substance onto the silicon-based dispersant. Preferably, the silicon-based dispersant is a spherical particle with a particle size of 20-60 μm (more preferably 35-45 μm) and a specific surface area of 200-600 m². 2 / g (more preferably 280-450m) 2 The pore volume is 0.5-3.5 mL / g (more preferably 1.0-2.5 mL / g), and the pore size is 30-100 μm (more preferably 20-50 μm).
[0016] In some specific embodiments, the alkylaluminum is selected from any one or more of triethylaluminum, trihexylaluminum, triisobutylaluminum, dichloroethylaluminum, and dichlorodiethylaluminum.
[0017] The alkylaluminum can be the above-mentioned pure product or an inert alkane solution thereof, wherein the inert alkane solution is selected from any one or more of n-hexane, cyclohexane, hexane, and n-heptane.
[0018] In some specific embodiments, in step S1, the amount of alkyl aluminum in the components of the post-treatment dispersant is based on the silicon content in the silicon-based dispersant, and the Si / Al molar ratio is 5-100:1.
[0019] In some specific embodiments, in step S1, the process conditions for fluidizing the silicon-based dispersant are as follows: the silicon-based dispersant is fluidized at 20-1500°C for 0.5-25 hours under inert gas or high-purity air purging conditions.
[0020] In some specific embodiments, in step S1, the inert alkane solvent in the components of the mother liquor is selected from any one or more of n-hexane, cyclohexane, hexane, and n-heptane;
[0021] The alkyl magnesium is selected from any one or more of n-butyl magnesium, isobutyl magnesium, n-butylisobutyl magnesium, dioctyl magnesium, butyloctyl magnesium, ethyl magnesium chloride, and butyl magnesium chloride.
[0022] The alkyl magnesium can be the above-mentioned pure product or an inert alkane solution thereof, wherein the inert alkane solution is selected from any one or more of n-hexane, cyclohexane, hexane, and n-heptane.
[0023] The alkylaluminum is of chemical formula R. 3-n Compounds of Al, wherein R is an alkyl group and n is 0 or an integer less than 3;
[0024] The monohydric alcohol is selected from any one or more of n-octanol and isooctanol.
[0025] In some specific embodiments, the alkylaluminum is selected from any one or more of triethylaluminum, trihexylaluminum, and triisobutylaluminum.
[0026] The alkylaluminum can be the above-mentioned pure product or an inert alkane solution thereof, wherein the inert alkane solution is selected from any one or more of n-hexane, cyclohexane, hexane, and n-heptane.
[0027] In some specific embodiments, in step S1, the mass ratio of inert alkane solvent to silicon-based dispersant in the mother liquor is 4-10:1; the mass ratio of alkyl magnesium to silicon-based dispersant is 0.01-1.0:1; the amount of alkyl aluminum is 0.00001-0.001 mol / g silicon-based dispersant; and the molar ratio of monohydric alcohol to alkyl magnesium is 0.1-5.0:1.
[0028] In some specific embodiments, in step S1, the mother liquor is obtained by reacting an inert alkane solvent, alkyl magnesium, alkyl aluminum, and a monohydric alcohol in an inert atmosphere at 15-45°C for 0.5-25 hours.
[0029] In some specific embodiments, in step S2, the titanium-containing compound is selected from any one or more of titanium tetrachloride, tetraethyl titanate, n-propyl titanate, isopropyl titanate, and n-butyl titanate.
[0030] The chemical formula of the alkoxysilane is Rn Si(OR6) 4-n , where R is an alkyl group and n is an integer less than 4.
[0031] In some specific embodiments, the alkoxysilane is selected from any one or more of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetran-butoxysilane, tetraisobutoxysilane, tetran-pentoxysilane, and tetraisopentoxysilane.
[0032] In some specific embodiments, in step S2, the ratio of the mother liquor to the post-treatment dispersant is 0.01-1.0:1 by mass of alkyl magnesium to silicon-based dispersant;
[0033] The amount of titanium-containing compound used is 0.0001-0.001 mol / g of silicon-based dispersant, and the alkoxysilane is used at a titanium-silicon molar ratio of 1-6:1 with the titanium-containing compound.
[0034] In some specific embodiments, in step S2, the reaction conditions between the mother liquor and the post-treatment dispersant are: stirring thoroughly at 5-50°C for 0.5-25 hours;
[0035] The reaction conditions for adding titanium-containing compounds are: stirring thoroughly at 5-50℃ for 0.5-25 hours;
[0036] The reaction conditions for adding alkoxysilane are: stirring thoroughly at 5-50℃ for 0.5-3 hours.
[0037] In some specific embodiments, the post-treatment dispersant obtained from step S1 is further subjected to solvent evaporation and drying.
[0038] The polyethylene catalyst obtained from step S2 is further subjected to solvent evaporation and drying.
[0039] The second technical solution of the present invention is to provide a polyethylene catalyst, which is prepared by the preparation method described in one of the above technical solutions.
[0040] The third technical solution of the present invention is to provide an application of the polyethylene catalyst as described in the second technical solution above, wherein the polyethylene catalyst is used for long-stay reaction ethylene polymerization in an ethylene gas-phase polymerization apparatus.
[0041] In some specific implementations, a long residence time is defined as a residence reaction time of more than 2 hours.
[0042] Compared with the prior art, the present invention has the following beneficial effects:
[0043] (1) The polyethylene catalyst preparation method provided by the present invention is simple and feasible, and the raw material cost is low. The main features are: THF in the prior art is easily oxidized to form peroxide. When the peroxide accumulates to a certain extent, it will cause danger to the use of THF and pose a huge threat to the subsequent production process.
[0044] The preparation method provided by this invention effectively overcomes the above-mentioned problems by replacing ether solvents such as tetrahydrofuran (THF) with stable inert alkane solvents.
[0045] This invention replaces the traditional AA titanium trichloride with a low-cost and domestically produced titanium-containing compound, such as titanium tetrachloride, to provide the active titanium center for the catalyst, and reduces the amount of titanium-containing compound used.
[0046] (2) The polyethylene catalyst prepared by this invention exhibits stable kinetic behavior, as reflected in:
[0047] This invention stabilizes the active centers of titanium by adding alkoxysilane as a modifier, which slows down the catalyst breakage rate, thereby reducing the polymerization rate in the catalytic ethylene polymerization process and stabilizing the kinetic behavior, making it suitable for reactors with long residence times.
[0048] (3) The polymerization products catalyzed by the polyethylene catalyst prepared by this invention have high bulk density, which is reflected in:
[0049] This invention stabilizes the active centers of titanium by adding alkoxysilane as a modifier, which slows down the catalyst breakage rate, thereby reducing the polymerization rate in the catalytic ethylene polymerization process and resulting in a higher bulk density of the polymer product, making it suitable for reactors with long residence times. Attached Figure Description
[0050] Figure 1 The kinetic properties of the polyethylene catalyst prepared in this invention are shown. Detailed Implementation
[0051] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0052] Unless otherwise specified, the raw materials or processing techniques used in the following embodiments and comparative examples are all conventional commercially available raw materials or conventional processing techniques in the art.
[0053] Example 1:
[0054] A three-necked flask equipped with a magnetic stirrer was filled with 10 g of silica gel treated with nitrogen flow at 800 °C for 8 h, 35 mL of n-hexane, and 1.5 g of dichloroethylaluminum at 45 °C. After reacting for 1 h, the mixture was dried to obtain the post-treated dispersant. The silica gel used had a particle size of 20 μm and a specific surface area of 285 m². 2 / g, pore volume 1.24mL / g.
[0055] A four-necked flask equipped with a magnetic stirrer was filled with 1.3 g of n-butylmagnesium, 0.5 mL of triethylaluminum, and 40 mL of n-hexane under nitrogen protection, and stirred at 25 °C for 0.5 h. Then, 3 mL of isooctanol was added dropwise to the flask through a dropping funnel. After the addition was complete, the mixture was stirred at 25 °C for 5 h to obtain the mother liquor.
[0056] The mother liquor was added dropwise to the post-treatment dispersant, and the mixture was stirred at 45°C for 1 hour after the addition was complete. 0.65 mL of titanium tetrachloride was then added dropwise to a three-necked flask using a dropping funnel. The mixture was stirred at 45°C for 5 hours after the addition was complete. 0.4 mL of tetraethoxysilane was then added, and the mixture was reacted at 45°C for 1 hour.
[0057] After the reaction was completed, the solvent was evaporated and then dried to obtain the finished catalyst CAT1.
[0058] Example 2:
[0059] A three-necked flask equipped with a magnetic stirrer was filled with 10 g of silica gel treated with nitrogen flow at 800 °C for 8.5 h, 35 mL of n-hexane, and 1.5 g of dichloroethylaluminum at 45 °C. After reacting for 1 h, the mixture was dried to obtain the post-treatment dispersant. The silica gel used had a particle size of 22 μm and a specific surface area of 300 m². 2 / g, pore volume 1.23mL / g.
[0060] Under nitrogen protection, 1.4 g of isobutylmagnesium, 0.1 mL of triethylaluminum, and 40 mL of n-hexane were added to a four-necked flask equipped with a magnetic stirrer, and the mixture was stirred at 25 °C for 0.5 h. Then, 2 mL of isooctanol was added dropwise to the flask through a dropping funnel. After the addition was complete, the mixture was stirred at 25 °C for 5 h to obtain the mother liquor.
[0061] The mother liquor was added dropwise to the post-treatment dispersant, and the mixture was stirred at 45°C for 1 hour after the addition was complete. 0.65 mL of titanium tetrachloride was then added dropwise to a three-necked flask using a dropping funnel. The mixture was stirred at 45°C for 5 hours after the addition was complete. 0.4 mL of tetraethoxysilane was then added, and the mixture was reacted at 45°C for 1 hour.
[0062] After the reaction is complete, the solvent is evaporated and then dried to obtain the finished catalyst CAT2.
[0063] Example 3:
[0064] A three-necked flask equipped with a magnetic stirrer was filled with 10 g of silica gel treated with nitrogen flow at 800 °C for 8 h, 35 mL of n-hexane, and 1.5 g of dichloroethylaluminum at 45 °C. After reacting for 1 h, the mixture was dried to obtain the post-treatment dispersant. The silica gel used had a particle size of 25 μm and a specific surface area of 330 m². 2 / g, pore volume 1.23mL / g.
[0065] A four-necked flask equipped with a magnetic stirrer was filled with 13 g of a hexane solution containing 15 wt% n-butylisobutylmagnesium under nitrogen protection, followed by 0.1 mL of triethylaluminum and 40 mL of n-hexane. The mixture was stirred at 25 °C for 0.5 h. Then, 1 mL of n-octanol was added dropwise to the flask using a dropping funnel. After the addition was complete, the mixture was stirred for 5 h to obtain the mother liquor.
[0066] The mother liquor was added dropwise to the post-treatment dispersant, and the mixture was stirred at 45°C for 1 hour after the addition was complete. 0.65 mL of titanium tetrachloride was then added dropwise to a three-necked flask using a dropping funnel. The mixture was stirred at 45°C for 5 hours after the addition was complete. 0.4 mL of tetraethyl orthosilicate was then added, and the mixture was reacted at 45°C for 1 hour.
[0067] After the reaction is complete, the solvent is evaporated and then dried to obtain the finished catalyst CAT3.
[0068] Comparative Example 1:
[0069] A three-necked flask equipped with a magnetic stirrer was filled with 10 g of silica gel treated with nitrogen flow at 800 °C for 8 h, 35 mL of n-hexane, and 1.5 mL of dichloroethylaluminum at 45 °C. After reacting for 1 h, the mixture was dried to obtain the post-treatment dispersant. The silica gel used had a particle size of 225 μm and a specific surface area of 325 m². 2 / g, pore volume 1.25mL / g.
[0070] Under nitrogen protection, 3 g of magnesium chloride and 150 mL of tetrahydrofuran were added dropwise to a three-necked flask equipped with a magnetic stirrer. Then, 3 mL of isooctanol was added dropwise through a dropping funnel, and the mixture was stirred at 50 °C for 3 h. 1.35 g of TiCl3·1 / 3AlCl3 was added, and the reaction was continued for another 3 h to obtain the mother liquor.
[0071] The mother liquor was added dropwise to the post-treatment dispersant, and the mixture was stirred for 1 hour after the addition was complete. After the reaction was complete, the tetrahydrofuran was evaporated to 15 wt%. 150 mL of n-hexane was added, followed by 2.5 g of triisobutylaluminum. After reacting for 0.5 hours, the solvent n-hexane was evaporated and the mixture was dried to obtain the reference catalyst CAT4.
[0072] In this comparative example, the catalyst preparation method used a large amount of ether THF as a solvent and TiCl3·1 / 3AlCl3 as the source of the active center Ti.
[0073] The catalysts prepared in the above embodiments and comparative examples were subjected to catalyst component analysis, small-scale polymerization activity evaluation, and resin analysis, as shown in Table 1.
[0074] (1) The composition of the catalyst was analyzed using the following methods:
[0075] The contents of Al and Mg were determined by disodium ethylenediaminetetraacetate (EDTA) complexometric titration.
[0076] The Ti content was determined by spectrophotometric colorimetry.
[0077] The Cl content was determined by potentiometric titration.
[0078] The alcohol content was obtained by gas chromatography analysis of the extract obtained by extracting the catalyst solid.
[0079] (2) The following methods were used for small-scale aggregate evaluation:
[0080] A 2L stainless steel reactor was heated to 65°C and evacuated, then purged with purified high-purity nitrogen. 1000mL of purified, dried hexane, 1.0mL of triethylaluminum co-catalyst, and the catalyst were added to replace the high-purity nitrogen in the reactor with ethylene. Stirring was then started, and ethylene was continuously added while the temperature was raised to 85°C. The reaction was carried out at 85°C for 2 hours. After the polymerization reaction was completed, the ethylene reaction was stopped, and the mixture was cooled before separating the polyethylene powder from the hexane. The powder was dried, weighed, and the polymerization activity was calculated.
[0081] Calculation of polymerization activity:
[0082] Activity (KgPE / Kgcat) = Polyethylene weight (g) / Catalyst weight (g)
[0083] (3) The following methods were used for the analysis and testing of polyethylene resin:
[0084] Polyethylene resin bulk density: determined according to ASTM-D1895;
[0085] Determination of the particle size distribution of polyethylene resin: sieve using a standard sieve.
[0086] The results are shown in Table 1:
[0087] Table 1
[0088]
[0089] As can be seen from Table 1, compared with CAT4, the polymerization activity of CAT1 to CAT3 is basically not greatly affected, the resin bulk density is increased, and the resin sieve results ≤120 mesh are reduced.
[0090] The kinetic properties of the catalysts prepared in the above embodiments and comparative examples are shown in [reference needed]. Figure 1 ,from Figure 1 As can be seen, the catalysts CAT1, CAT2, and CAT3 prepared by this invention have more stable kinetic behavior than CAT4 prepared by Comparative Example 1.
[0091] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A method for preparing a polyethylene catalyst, characterized in that, Includes the following steps: S1. After fluidizing the silicon-based dispersant, disperse it in an inert alkane solvent and add alkyl aluminum to obtain a post-treatment dispersant; An inert alkane solvent, alkyl magnesium, alkyl aluminum, and a monohydric alcohol are mixed to obtain a mother liquor. S2. The mother liquor obtained in step S1 is added dropwise to the post-treatment dispersant for reaction. A titanium-containing compound is added to continue the reaction, and an alkoxysilane is added to continue the reaction to obtain a polyethylene catalyst.
2. The method for preparing the polyethylene catalyst according to claim 1, characterized in that, In step S1, the silica-based dispersant is selected from any one or more of silica gel, silica gel-alumina, and silica gel-titanium dioxide. The inert alkane solvent is selected from any one or more of n-hexane, cyclohexane, hexane, and n-heptane; The alkylaluminum is of chemical formula R. 3-n AlX n Compounds in which R is an alkyl group, X is a halogen, and n is 0 or an integer less than 3; In the components of the mother liquor, the inert alkane solvent is selected from any one or more of n-hexane, cyclohexane, hexane, and n-heptane; The alkyl magnesium is selected from any one or more of n-butyl magnesium, isobutyl magnesium, n-butylisobutyl magnesium, dioctyl magnesium, butyloctyl magnesium, ethyl magnesium chloride, and butyl magnesium chloride. The alkylaluminum is of chemical formula R. 3-n Compounds of Al, wherein R is an alkyl group and n is 0 or an integer less than 3; The monohydric alcohol is selected from any one or more of n-octanol and isooctanol.
3. The method for preparing the polyethylene catalyst according to claim 2, characterized in that, In the components of the post-treatment dispersant, the alkylaluminum is selected from any one or more of triethylaluminum, trihexylaluminum, triisobutylaluminum, dichloroethylaluminum, and dichlorodiethylaluminum; In the components of the mother liquor, the alkyl aluminum is selected from any one or more of triethylaluminum, trihexylaluminum, and triisobutylaluminum.
4. The method for preparing the polyethylene catalyst according to claim 1, characterized in that, In step S1, the amount of alkyl aluminum in the post-treatment dispersant is based on the silicon content in the silicon-based dispersant, and the Si / Al molar ratio is 5-100:
1. In the components of the mother liquor, the mass ratio of inert alkane solvent to silicon-based dispersant is 4-10:1; the mass ratio of alkyl magnesium to silicon-based dispersant is 0.01-1.0:1; the amount of alkyl aluminum is 0.00001-0.001 mol / g silicon-based dispersant; and the molar ratio of monohydric alcohol to alkyl magnesium is 0.1-5.0:
1.
5. The method for preparing the polyethylene catalyst according to claim 1, characterized in that, In step S1, the process conditions for fluidizing the silicon-based dispersant are as follows: the silicon-based dispersant is fluidized at 20-1500℃ for 0.5-25h under inert gas or high-purity air purging conditions. The mother liquor is obtained by reacting an inert alkane solvent, alkyl magnesium, alkyl aluminum, and a monohydric alcohol in an inert atmosphere at 15-45°C for 0.5-25 hours.
6. The method for preparing the polyethylene catalyst according to claim 1, characterized in that, In step S2, the titanium-containing compound is selected from any one or more of titanium tetrachloride, tetraethyl titanate, n-propyl titanate, isopropyl titanate, and n-butyl titanate. The chemical formula of the alkoxysilane is R n Si(OR6) 4-n , where R is an alkyl group and n is an integer less than 4.
7. The method for preparing the polyethylene catalyst according to claim 6, characterized in that, The alkoxysilane is selected from any one or more of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetran-butoxysilane, tetraisobutoxysilane, tetran-pentoxysilane, and tetraisopentoxysilane.
8. The method for preparing the polyethylene catalyst according to claim 1, characterized in that, In step S2, the ratio of the mother liquor to the post-treatment dispersant is 0.01-1.0:1 by mass of alkyl magnesium to silicon-based dispersant. The amount of titanium-containing compound used is 0.0001-0.001 mol / g of silicon-based dispersant, and the alkoxysilane is used at a titanium-silicon molar ratio of 1-6:1 with the titanium-containing compound. The reaction conditions for the mother liquor and the post-treatment dispersant are: stirring thoroughly at 5-50℃ for 0.5-25 hours; The reaction conditions for adding titanium-containing compounds are: stirring thoroughly at 5-50℃ for 0.5-25 hours; The reaction conditions for adding alkoxysilane are: stirring thoroughly at 5-50℃ for 0.5-3 hours.
9. A polyethylene catalyst, characterized in that, It was prepared according to the preparation method of the polyethylene catalyst according to any one of claims 1-8.
10. An application of the polyethylene catalyst as described in claim 9, characterized in that, The polyethylene catalyst is used for ethylene polymerization in long-stay reactions in an ethylene gas-phase polymerization unit.