Ethylene polymerization catalyst, process for its preparation and use

Abstract

The present application relates to a kind of ethylene polymerization catalyst and its preparation method and application, the solid formed by MgCl2 alcohol compound after dealcoholization is carrier, TiCl4 is reacted with the carrier to form titanium tetrachloride magnesium initial state catalyst;Different structures of aromatic ether compounds are added as internal donor, the internal donor and titanium tetrachloride magnesium initial state catalyst synergistic effect, finally form the high activity, high copolymerization performance of the ethylene polymerization catalyst of the present application.By optimizing carrier preparation process, screening suitable aromatic ether internal donor, the technical problems of the existing catalyst polymerization activity is low, copolymerization performance is insufficient, product molecular weight distribution control is difficult, the catalyst polymerization activity is high, stability is good, copolymer monomer insertion rate is high, the comprehensive performance of the polyethylene material prepared is excellent, can be widely used in polyethylene homo- and copolymerization product industrial production, preparation process is simple, cost controllable, can realize large-scale industrialization amplification.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and relates to an ethylene polymerization catalyst, its preparation method, and its application. Background Technology

[0002] Polyethylene is one of the world's most produced and widely used synthetic polymer materials. Based on different polymerization processes and product properties, it can be classified into low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene, etc. Its performance mainly depends on the activity, selectivity, and copolymerization properties of the catalyst. Ziegler-Natta (ZN) type catalysts are the most widely used catalyst system in the industrial production of polyethylene due to their high catalytic efficiency, low cost, and strong product adaptability.

[0003] The support is a core component of Zn catalysts. Its structure, specific surface area, pore volume, and other properties directly affect the number, distribution, and structure of active sites, thus determining the catalyst's polymerization activity and product performance. In existing technologies, Zn catalyst supports often utilize nascent magnesium compounds (such as magnesium chloride and magnesium hydroxide). These supports require complex preparation processes and suffer from drawbacks such as small specific surface area, insufficient pore volume, and uneven dispersion of active sites. This results in low catalyst polymerization activity, difficulty in comonomer insertion, and an inability to meet the production requirements of high-performance polyethylene copolymers.

[0004] To address these issues, the industry has attempted to optimize support preparation processes, with the technology of preparing supports from MgCl2 alcohols through dealcoholization gradually gaining attention. However, in existing technologies, the selection of alcohols for MgCl2 alcohols is often limited to a single alcohol, and the dealcoholization process is not precisely controlled, resulting in excessively high residual alcohol content in the support, which affects the subsequent loading of TiCl4 and the formation of active centers. Simultaneously, the selection of internal electron donors and their compatibility with the support and main catalyst are insufficient, especially regarding the structural regulation and synergistic effects of aromatic ether internal electron donors. This lack of in-depth research prevents them from fully leveraging their regulatory role on active centers, resulting in limited improvement in catalyst copolymerization performance and making it difficult to achieve a synergistic balance between high activity and high copolymerization performance.

[0005] In summary, existing Zn catalysts suffer from the following core technical bottlenecks: First, the support preparation process is complex, and the support performance is poor, resulting in low catalyst activity. Second, the choice of alcohols for MgCl2 alcohol dehydration supports is limited, the dehydration process is imprecise, and excessive alcohol residue affects the formation of active centers. Third, the structure of the electron donor in aromatic ethers is not well-suited to the support and the main catalyst, resulting in poor synergistic effect and limited copolymerization performance. Therefore, developing an ethylene polymerization catalyst with MgCl2 as the dehydration support, suitable for aromatic ether electron donors, and high activity and high copolymerization performance to solve the above technical problems would have significant novelty, inventiveness, and industrial application value. Summary of the Invention

[0006] The purpose of this invention is to provide an ethylene polymerization catalyst, its preparation method, and its application. It is applicable to gas-phase and slurry polymerization processes for ethylene homopolymerization and copolymerization of ethylene with α-olefins (1-butene, 1-hexene, etc.), and can be used to prepare high-performance polyethylene homopolymer and copolymer products.

[0007] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a method for preparing an ethylene polymerization catalyst, using a solid formed by heating and de-alcoholizing a MgCl2 alcohol as a support, and reacting TiCl4 with the support to form a titanium tetrachloride magnesium chloride nascent catalyst; adding aromatic ether compounds with different structures as internal electron donors, the internal electron donors and the titanium tetrachloride magnesium chloride nascent catalyst working synergistically to finally form the highly active ethylene polymerization catalyst with high copolymerization performance.

[0008] Specifically, the preparation method of the present invention includes the following steps: Preparation of S1 and MgCl2 alcohols: Under inert gas protection, anhydrous MgCl2 and a monohydric alcohol were added to a reaction vessel, toluene was used as a solvent, the temperature was raised to 80-120℃, and the reaction was stirred for 1.0-4.0 h to form a homogeneous and transparent MgCl2 alcohol system. S2, Preparation of the support: The MgCl2 alcohol system prepared in S1 was heated to 120-180℃ and vacuum degree 0.06-0.10 MPa, and subjected to alcohol removal treatment for 2.0-6.0h. The alcohol residue of the support was controlled to be ≤0.5wt%. The system was then cooled to room temperature to obtain the alcohol-removed MgCl2 support. Preparation of S3 and titanium tetrachloride / magnesium chloride nascent catalyst: Under an inert atmosphere, the MgCl2 support obtained from S2 after alcohol removal was added to a reaction vessel. Toluene was used as a solvent, and the temperature was lowered to -5~15℃. Then TiCl4 was added dropwise, and the reaction was stirred for 0.5~3.0h. Subsequently, the temperature was raised to 40~60℃, and the reaction was maintained at this temperature and stirred for 1.0~3.0h to form titanium tetrachloride / magnesium chloride nascent catalyst. S4. Catalyst Formation: Add an aromatic ether internal electron donor to the titanium tetrachloride / magnesium chloride initial state catalyst in S3, heat to 50~70℃, and stir for 1.0~3.0h. After the reaction is completed, filter, wash, and dry to obtain the ethylene polymerization catalyst.

[0009] Furthermore, in S1, the monohydric alcohol is one or a mixture of two or more of ethanol, isooctanol, and butanol in any proportion.

[0010] Furthermore, in S1, the molar ratio of MgCl2 to monohydric alcohol is 1:(1.0-5.0), preferably 1:(2.0-3.5). This molar ratio ensures that MgCl2 is fully dissolved to form a homogeneous alcohol complex system, avoiding incomplete de-alcoholization and excessive alcohol residue due to excessive monohydric alcohol, or insufficient alcohol leading to inadequate alcohol complex formation and carrier structure defects due to insufficient monohydric alcohol.

[0011] Furthermore, in S1, the amount of toluene used is 3-8 times the mass of anhydrous MgCl2.

[0012] Furthermore, in S2, the specific surface area of ​​the carrier is 100-300 m². 2 / g, pore volume 0.3-0.8 cm³ 3 / g, with a particle size of 20-80 μm. By precisely controlling the dealcoholization process, free alcohols and bound alcohols in the alcoholic compounds can be effectively removed, reducing the impact of residual alcohols on the formation of active centers; the specific surface area, pore volume and particle size range of the carrier can ensure uniform loading of TiCl4, forming a sufficient number and uniformly dispersed active centers.

[0013] Furthermore, the molar ratio of TiCl4 and MgCl2 supports to the electron donors in aromatic ethers is 1:(8-20):(0.1-0.7).

[0014] Furthermore, in S3, through a two-step reaction, the low-temperature reaction can avoid the hydrolysis of TiCl4 and ensure the full coordination of TiCl4 with the support, while the heating and holding can promote the further reaction and form a stable titanium tetrachloride and magnesium chloride initial state catalyst with sufficient active centers; the inert atmosphere protection can prevent the raw materials and products from being oxidized and improve the stability of the catalyst.

[0015] Furthermore, in S4, the inert atmosphere is provided by nitrogen or argon.

[0016] Furthermore, in S4, the electron donor within the aromatic ether is one or a mixture of two or more of anisole, phenylbutanol, p-methyl anisole, p-methoxyanisole, and o-phthalic acid in any proportion.

[0017] In a second aspect, the present invention provides an ethylene polymerization catalyst, which is prepared by the preparation method described in the first aspect.

[0018] In a third aspect, the present invention provides the application of an ethylene polymerization catalyst in the homopolymerization of ethylene or the copolymerization of ethylene with α-olefins to prepare polyethylene. Specifically, the prepared polyethylene material has a viscosity-average molecular weight of 150 × 10⁻⁶. 4 ~300×10 4 The molecular weight distribution is 4.5–7.5, and the bulk density is 0.30–0.38 g·cm³. 3-3Tensile strength ≥38.0 MPa, elongation at break ≥400%, comonomer insertion rate of copolymer products ≥8.5%, impact strength ≥180 kJ·m -2 This material boasts excellent performance and can meet the application needs of high-end fields such as packaging, pipes, and films.

[0019] Furthermore, the α-olefin is one or a mixture of two or more of 1-butene, 1-hexene, and 1-octene in any proportion.

[0020] Compared with the prior art, the present invention has the following advantages: (1) Using the solid formed by heating and de-alcoholizing MgCl2-monohydrin (ethanol, isooctyl alcohol, butanol, etc.) as a support breaks through the limitations of conventional support preparation and simplifies the support preparation process. At the same time, the performance of the support is optimized by precisely controlling the de-alcoholizing process. For the first time, aromatic ether compounds with different structures are screened as internal electron donors to form a synergistic effect with the titanium tetrachloride magnesium chloride primary state catalyst. This is different from the application of single-structure aromatic ether electron donors in the present. It fills the technical gap of synergistic regulation of "MgCl2-monohydrin de-alcoholizing support-primary state catalyst-multi-structure aromatic ether electron donor" and has significant novelty.

[0021] (2) The preparation of the support by the de-alcoholization of MgCl2 alcohols solves the technical problems of complex preparation process and poor performance of traditional support. The specific surface area and pore volume of the support are significantly improved and the active sites are evenly dispersed. By taking advantage of the synergistic effect of the electron donor in the aromatic ether with different structures and the initial catalyst, the electronic environment and spatial structure of the active center are precisely controlled, and the synergistic breakthrough of "high activity" and "high copolymerization performance" of the catalyst is achieved. This effectively solves the core problem of "high activity and high copolymerization performance cannot be taken into account" in the existing technology and has significant creativity. Detailed Implementation

[0022] The present invention will now be described in detail with reference to 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.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0024] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0025] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0026] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0027] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0028] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0029] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0030] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0031] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0032] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0034] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0035] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0036] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, but sequentially is preferred.

[0037] In the following examples, the performance indicators of each polymer were determined using the following methods. Melt flow index (MI) determination: determined according to ASTM-D1238, under condition E, 190°C; Polymer density determination: determined according to ASTM-1050; Polymer bulk density determination: determined according to ASTM-D1895; Determination of polymer particle size distribution: Sieving was performed using standard sieves.

[0038] Determination of polymer molecular weight distribution: Molecular weight distribution was determined using a PL-GPC220 instrument at a temperature of 150℃, with trichlorobenzene as the solvent and a sample concentration of 0.1 mg / ml.

[0039] Example 1: Preparation of MgCl2 / isooctanol Under strict protection of high-purity nitrogen, 20 g of anhydrous MgCl2 and 0.35 mol of isooctanol were added to a 500 mL three-necked flask, along with 100 mL of toluene as a solvent. The mixture was slowly heated to 100 °C and stirred continuously for 2.5 h to form a homogeneous and transparent MgCl2-isooctanol ethanolate system. The ethanolate system was found to be homogeneous and stable, with no obvious precipitate. Rapid stirring and cooling formed a magnesium chloride ethanolate, which was then washed several times with n-hexane.

[0040] The prepared MgCl2-isooctanol ethanol compound was heated to 150℃ and subjected to a vacuum of 0.08 MPa for 4.0 h to remove alcohol, controlling the residual alcohol content of the support to be 0.32% (mass fraction). After cooling to room temperature, a white powdery MgCl2 support after alcohol removal was obtained. The specific surface area of ​​this support was measured to be 220 m² / g. 2 / g, pore volume 0.55 cm³ 3 / g, with a particle size of 40~60 μm, uniform structure, and no obvious agglomeration.

[0041] Under high-purity nitrogen protection, 10 g of the prepared dealcoholized MgCl2 support was added to a 500 mL three-necked flask, along with 80 mL of toluene as solvent. The flask was placed in an ice-water bath and cooled to 5 °C. 32 mL of TiCl4 was slowly added dropwise at a dropping rate of 1.5 mL / min, and the mixture was stirred at low temperature for 1.5 h. Subsequently, the temperature was gradually increased to 50 °C, and the mixture was stirred and maintained at this temperature for 2.0 h to form a pristine titanium tetrachloride-magnesium chloride catalyst. The system was a pale yellow suspension. The mixture was washed three times with n-hexane.

[0042] 0.35 mol of phenylbutyl ether was added to the above reaction system as an internal electron donor, the temperature was raised to 60℃, and the reaction was stirred for 2.0 h to allow the phenylbutyl ether and the initial catalysts of titanium tetrachloride and magnesium chloride to fully cooperate. After the reaction was completed, the product was filtered and washed four times with n-hexane (50 mL each time). The product was then vacuum dried at 60℃ and 0.08 MPa for 4.0 h to obtain the highly active and high copolymerization performance ethylene polymerization catalyst (denoted as Cat-1).

[0043] Testing revealed that the catalyst contained 5.6% titanium and had a polymerization activity of 9850 g·mol(Ti). -1 ·h -1 After being placed in air for 48 hours, the activity retention rate was 97.2%, demonstrating excellent activity and stability.

[0044] The 2 L high-pressure reactor was purged with high-purity nitrogen five times in succession. Then, 1 L of dehydrated n-hexane, 0.5 g of the catalyst prepared in Example 5, and 0.7 mL of triethylaluminum (co-catalyst) were added in sequence. A small amount of nitrogen was introduced to fully flush the solvent and catalyst into the reactor. The reactor was purged with nitrogen three times again, followed by purging with ethylene three times. A mixed gas of ethylene and 1-butene (10% molar fraction of 1-butene) was introduced to control the pressure inside the reactor to 0.9 MPa. Stirring was started (500 r / min), and the temperature was gradually increased to 75°C at a rate of 5°C / min. The reactor was kept at constant temperature and pressure for 2 hours for polymerization. After the reaction was completed, the gas source was turned off, and the reactor was allowed to cool naturally to room temperature. The copolymer was slowly depressurized and then removed. The copolymer was dried at 80°C and a vacuum of 0.08 MPa for 7 hours to obtain a high-performance polyethylene copolymer material.

[0045] The viscosity-average molecular weight of the copolymer was measured to be 240 × 10⁻⁶. 4 The molecular weight distribution is 6.3, and the bulk density is 0.35 g·cm³. 3-3 The tensile strength is 41.2 MPa, the elongation at break is 435%, and the impact strength is 192 kJ·m. -2 The 1-butene insertion rate is 9.8%, which fully meets the application requirements of high-end copolymer products.

[0046] Example 2: Preparation of catalyst (phenylbutyl ether + p-methoxyanisole as internal electron donor) The catalyst was largely the same as in Example 1, except that 0.35 mol phenylbutyl ether was replaced with 0.2 mol phenylbutyl ether and 0.15 mol p-methoxyanisole (a mixed internal electron donor). The resulting catalyst was designated Cat-2.

[0047] Testing revealed that the catalyst contained 5.8% titanium and had a polymerization activity of 10230 g·mol(Ti). -1 ·h -1 After being placed in air for 48 hours, the activity retention rate was 97.8%, and the activity and stability were further improved compared with Cat-1.

[0048] The procedures of Example 1 were repeated, except that the mixed gas was replaced with pure ethylene, while all other conditions remained exactly the same, to obtain a polyethylene homopolymer material. The viscosity-average molecular weight of this homopolymer material was measured to be 260 × 10⁻⁶. 4 The molecular weight distribution is 6.1, and the bulk density is 0.36 g·cm³. -3 The tensile strength is 42.5 MPa, the elongation at break is 420%, and the impact strength is 188 kJ·m. -2 It has excellent performance.

[0049] Comparative Example 1 The catalyst is largely the same as in Example 1, except that no aromatic ether internal electron donor is added, and the resulting catalyst is designated Cat-3.

[0050] The copolymerization of ethylene and 1-butene was carried out using Cat-3, and the copolymerization conditions were exactly the same as those in Example 1.

[0051] The catalyst was tested and found to have a polymerization activity of 6820 g·mol(Ti). -1 ·h -1 The activity was significantly reduced compared to Example 1, and after being placed in air for 48 hours, the activity retention rate was 82.5%; the viscosity-average molecular weight of the prepared copolymer was 180 × 10⁻⁶. 4 The molecular weight distribution is 3.9, the 1-butene insertion rate is 4.2%, the tensile strength is 32.1 MPa, and the impact strength is 145 kJ·m. -2 This demonstrates the synergistic advantage of the MgCl2-monohydrin dealcoholization support and the internal electron donor of aromatic ethers in this invention.

[0052] Comparative Example 2 Compared with Example 1, most of the contents are the same, except that the MgCl2-isooctanol alcohol compound (without heating and alcohol content of 35.2%) prepared in Example 1 is used directly as the support, and the resulting catalyst is designated as Cat-4; the copolymerization reaction of ethylene and 1-butene is carried out using Cat-4, and the copolymerization conditions are exactly the same as those in Example 1.

[0053] The catalyst was tested and found to have a polymerization activity of 7250 g·mol(Ti). -1 ·h -1 The catalyst contains only 3.2% titanium; the prepared copolymer has a viscosity-average molecular weight of 170 × 10⁻⁶. 4 The molecular weight distribution was 3.7, the 1-butene insertion rate was 3.8%, and the product performance decreased significantly, highlighting the necessity of the heating de-alcoholization process of this invention.

[0054] Comparative Example 3 The process was largely the same as in Example 1, except that 0.35 mol phenylbutyl ether was replaced with 0.35 mol anisole as the internal electron donor, and the resulting catalyst was designated Cat-5. The copolymerization of ethylene and 1-butene was carried out using Cat-5 under the same conditions as in Example 1.

[0055] The catalyst was tested and found to have a polymerization activity of 8360 g·mol(Ti). -1 ·h -1 The prepared copolymer material has an insertion rate of 6.5% for 1-butene, which demonstrates that the aromatic ether internal electron donors (phenylbutyl ether and p-methoxyanisole) of the present invention have a better synergistic regulation effect.

[0056] The above examples and comparative examples fully demonstrate that the present invention replaces the traditional nascent magnesium compound support with a MgCl2-monohydrin alcohol dehydrogenation support, and combines the synergistic effect of electron donors in aromatic ethers with different structures and the initial state catalyst of titanium tetrachloride and magnesium chloride, thus solving the core technical problems of the prior art, achieving a significant improvement in catalyst activity and copolymerization performance, and possessing significant novelty, inventiveness and industrial applicability, and can be applied on a large scale in industrial applications.

[0057] 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 an ethylene polymerization catalyst, characterized in that, Includes the following steps: Preparation of S1 and MgCl2 alcohols: Under inert gas protection, anhydrous MgCl2 and a monohydric alcohol were added to a reaction vessel, toluene was used as a solvent, the temperature was raised to 80-120℃, and the reaction was stirred for 1.0-4.0 h to form a homogeneous and transparent MgCl2 alcohol system. S2, Preparation of the support: The MgCl2 alcohol system prepared in S1 was heated to 120-180℃ and vacuum degree 0.06-0.10 MPa, and subjected to alcohol removal treatment for 2.0-6.0h. The alcohol residue of the support was controlled to be ≤0.5wt%. The system was then cooled to room temperature to obtain the alcohol-removed MgCl2 support. Preparation of S3 and titanium tetrachloride / magnesium chloride nascent catalyst: Under an inert atmosphere, the MgCl2 support obtained from S2 after alcohol removal was added to a reaction vessel. Toluene was used as a solvent, and the temperature was lowered to -5~15℃. Then TiCl4 was added dropwise, and the reaction was stirred for 0.5~3.0h. Subsequently, the temperature was raised to 40~60℃, and the reaction was maintained at this temperature and stirred for 1.0~3.0h to form titanium tetrachloride / magnesium chloride nascent catalyst. S4. Catalyst Formation: Add an aromatic ether internal electron donor to the titanium tetrachloride / magnesium chloride initial state catalyst in S3, heat to 50~70℃, and stir for 1.0~3.0h. After the reaction is completed, filter, wash, and dry to obtain the ethylene polymerization catalyst.

2. The method for preparing an ethylene polymerization catalyst according to claim 1, characterized in that, In S1, the monohydric alcohol is one or a mixture of two or more of ethanol, isooctyl alcohol, and butanol.

3. The method for preparing an ethylene polymerization catalyst according to claim 1, characterized in that, In S1, the molar ratio of MgCl2 to monohydric alcohol is 1:(1.0-5.0).

4. The method for preparing an ethylene polymerization catalyst according to claim 1, characterized in that, In S1, the amount of toluene used is 3-8 times the mass of anhydrous MgCl2.

5. The method for preparing an ethylene polymerization catalyst according to claim 1, characterized in that, The molar ratio of TiCl4 and MgCl2 supports to the internal electron donors of aromatic ethers is 1:(8-20):(0.1-0.7).

6. The method for preparing an ethylene polymerization catalyst according to claim 1, characterized in that, In S4, the inert atmosphere is provided by nitrogen or argon.

7. The method for preparing an ethylene polymerization catalyst according to claim 1, characterized in that, In S4, the electron donor of the aromatic ether is one or a mixture of two of phenylbutyl ether and p-methoxyanisole.

8. An ethylene polymerization catalyst, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The application of the ethylene polymerization catalyst as described in claim 8 in the preparation of polyethylene through homopolymerization of ethylene or copolymerization of ethylene with α-olefins.

10. The application according to claim 9, characterized in that, The α-olefin is one or a mixture of two or more of 1-butene, 1-hexene, and 1-octene.