Alkoxy magnesium carrier polyethylene catalyst main agent and preparation method thereof

Abstract

The invention belongs to the technical field of polyolefin catalysts, and particularly relates to an alkoxy magnesium carrier polyethylene catalyst main agent and a preparation method thereof, an alkoxy magnesium carrier polyethylene catalyst composed of the main agent and a preparation method of the alkoxy magnesium carrier polyethylene catalyst. The main agent is formed by loading titanium-containing halide and aryl-containing ester compounds on an alkoxy magnesium carrier. The alkoxy magnesium carrier polyethylene catalyst provided by the invention has high catalytic activity, and is suitable for producing an ultra-high molecular weight polyethylene product by a slurry polymerization process.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyolefin catalysts, and particularly relates to a main agent of an alkoxymagnesium-supported polyethylene catalyst and a preparation method thereof, as well as an alkoxymagnesium-supported polyethylene catalyst composed of the main agent and a preparation method thereof. Background Art

[0002] In industrial production, the particle morphology, particle size distribution, fluidity and apparent density of polyethylene directly restrict the production capacity, long-term operation stability and energy consumption of the device. These properties of polyethylene mainly depend on the performance of the catalyst used, and are also closely related to the polymerization process technology. The slurry polymerization process is the most important production technology for high-density polyethylene in China. At present, most of the high-density polyethylene produced by the autoclave slurry reaction in China uses Ziegler-Natta titanium (series) catalysts supported on magnesium chloride. Most of the preparation routes of such catalysts are to dissolve magnesium chloride with Lewis bases such as alcohols, esters and ethers to form a complex solution, and then precipitate under the action of titanium compounds to form a catalyst precursor. The technical solutions of such catalysts are disclosed in patent documents such as CN1861650A, ZL00819563.3, CN101148485A, CN100577696C, CN105566524B, CN101148484B, CN1746197A, CN102718901A, CN103772536A, CN113024697A, CN106632753A, CN106632750B, CN106589179A, etc. Such catalysts generally have the advantages of high polymerization activity and concentrated particle size distribution, but usually have poor hydrogen response sensitivity and are often used in ethylene slurry polymerization to prepare ultra-high molecular weight polyethylene, ethylene and α-olefin copolymerization, etc.

[0003] The preparation technical routes of magnesium alkoxide-based catalysts mainly include: one is to process magnesium alkoxide into spherical particles and then react the particles with a titanium compound in an inert solvent to form a catalyst precursor; the second is to react metallic magnesium with a fatty alcohol under the initiation of a chlorine-containing initiator to obtain a magnesium alkoxide carrier, and then react the carrier with a titanium compound to obtain a catalyst; the third is to prepare magnesium alkoxide composite microsphere particles by methods such as suspension spraying of magnesium alkoxide and magnesium chloride, and then react the composite microsphere particles with a titanium compound to obtain a catalyst; the fourth is to dissolve magnesium alkoxide and titanium alkoxide to form a solution containing magnesium alkoxide and titanium alkoxide, and precipitate to form a catalyst under the action of a chlorinating reagent and an alkylaluminum. These methods are disclosed in patent documents such as CN109320639A, CN1989157A, CN114316102A, CN109503741B, CN101120025A, CN102947352A, CN105713116A, US7759445B2, US4859749A, CN100523015C, CN102066429A, CN1127525C, CN1675261A, etc. This type of catalyst has advantages such as high activity and good hydrogen regulation sensitivity, but the powder of this type of catalyst has poor fluidity, the preparation process is relatively complex, the bulk density of the powder needs to be improved, and most of this type of catalyst is applied to the preparation of 1-olefin homopolymers and copolymers, and the development of resin products with a bimodal molecular weight distribution, and is not suitable for the development of ultra-high molecular weight polyethylene products.

[0004] Patent CN94105011 relates to a method of reacting dialkylmagnesium with a halogenating agent to form a magnesium halide reactant, and then reacting with a titanium compound, which can prepare ultra-high molecular weight polyethylene with a narrow particle size distribution and small particle size, but the reaction process is complex. The preparation of ultra-high molecular weight polyethylene involved in patent CN93103156.7 uses a double carrier catalyst. Patent CN103554310A discloses a method for preparing a spherical carrier-supported olefin polymerization catalyst, which is to add a magnesium alkoxide spherical carrier to a solvent to form a magnesium alkoxide spherical carrier slurry, then add a chemical treatment agent of a Group IVB metal halide for treatment, and then obtain it through filtration, washing, and drying. This catalyst can be used to prepare ultra-high molecular weight polyethylene under slurry polymerization conditions, but the catalyst activity is low, and the ash content in the prepared polymer is high, affecting the product quality.

[0005] In view of the above situation, it is still very necessary to develop a catalyst with high polymerization activity, good polymer particle morphology, high bulk density of polymer powder, more concentrated particle size distribution, accurate regulation of polymer molecular weight, and suitable for slurry polymerization process. Summary of the Invention

[0006] The object of the present invention is to provide an alkoxymagnesium-supported polyethylene catalyst suitable for producing ultra-high molecular weight polyethylene products by a slurry polymerization process and a preparation method thereof.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] According to a first aspect of the present invention, there is provided a main agent of an alkoxymagnesium-supported polyethylene catalyst, which is composed of an alkoxymagnesium support loaded with a titanium halide compound and an aryl ester compound.

[0009] According to some embodiments of the present invention, the chemical structural formula of the alkoxymagnesium support is Mg(OR1)(OR2), where R1 and R2 are both alkyl groups containing 2 to 10 carbon atoms; preferably, R1 and R2 are both ethyl groups.

[0010] According to some embodiments of the present invention, the alkoxymagnesium support is a spherical-like particle with an average particle size of 20 to 1500 μm and a bulk density of 0.30 to 0.40 g / cm 3 ; preferably, the average particle size of the alkoxymagnesium support is 200 to 700 μm and the bulk density is 0.32 to 0.38 g / cm 3 .

[0011] According to some embodiments of the present invention, the aryl ester compound is at least one of di-n-butyl phthalate, diisobutyl phthalate, 1,3-dipentyl phthalate, methyl phenylacetate, ethyl benzoate, 1,3-butanediol dimethylbenzoate, 2,3-dimethyl-1,3-butanediol dibenzoate, phenethyl acrylate, phenyl methacrylate, 2-phenylethyl acrylate, 2,4-pentanediol dibenzoate, 2-methyl-3,5-heptanediol dibenzoate, 2,4-pentanediol dibenzoate, 4-ethyl-3,5-heptanediol dibenzoate; based on per mole of the alkoxymagnesium support, the amount of the aryl ester compound used is 0.1 - 100 moles, preferably 0.3 - 30 moles.

[0012] According to some embodiments of the present invention, the titanium halide compound is selected from at least one of the general formula (R1O)aTi(OR2)b(OR3)cXd, where a, b, c are integers between 0 and 4, d is an integer between 1 and 4, and a + b + c + d = 4, R1, R2, R3 are hydrogen and / or alkyl groups, and X is at least one of chlorine and bromine; preferably, the titanium halide compound is selected from at least one of titanium tetrachloride, titanium tetrabromide, chloro-triethoxy titanium, dichloro-diethoxy titanium, trichloro-ethoxy titanium, triisopropoxy titanium chloride; based on per mole of the alkoxymagnesium support, the amount of the titanium halide compound used is 0.1 - 40 moles, preferably 1 - 20 moles.

[0013] According to a second aspect of the present invention, there is provided a method for preparing a main agent of an alkoxymagnesium-supported polyethylene catalyst as described above, which comprises the following steps:

[0014] Under the protection of an inert gas, disperse the alkoxymagnesium support in an inert hydrocarbon organic solvent, then add an organic alcohol, stir and heat to 50 - 100 °C to obtain an alkoxymagnesium support dispersion;

[0015] Add an aryl ester compound to the alkoxymagnesium support dispersion, heat to 60 - 150 °C, stir and react for 1 - 4 hours, then cool to room temperature to obtain a mixed solution;

[0016] Add the mixed solution to a titanium halide preheated to 60 - 80 °C, react for 0.5 - 2 hours to obtain a suspension;

[0017] Cool the suspension to 0 - 40 °C, add a silicon-containing compound, stir and react for 0.5 - 4 hours to form a catalyst intermediate;

[0018] Perform ultrasonic treatment on the catalyst intermediate;

[0019] Heat the ultrasonically treated catalyst intermediate to 40 - 80 °C, add an ether compound, stir and react for 0.5 - 4 hours, and after washing with an organic solvent, obtain the main catalyst.

[0020] According to some embodiments of the present invention, the inert hydrocarbon organic solvent is at least one of aliphatic hydrocarbons, cycloalkanes, and aromatic hydrocarbons; preferably, the inert hydrocarbon organic solvent is decane, toluene; based on per mole of the alkoxymagnesium support, the amount of the inert hydrocarbon organic solvent used is 4 - 40 moles.

[0021] According to some embodiments of the present invention, the organic alcohol is at least one of straight-chain alcohols or isomeric alcohols with C1 - C20; preferably, the organic alcohol is isooctanol, ethylene glycol; based on per mole of the alkoxymagnesium support, the amount of the organic alcohol used is 0.02 - 0.2 moles, preferably 0.05 - 0.1 moles.

[0022] According to some embodiments of the present invention, the silicon-containing compound has the structure of R n SiCl 4-n wherein R is an alkyl group, hydrogen, or an oxygen-containing group, and 0 ≤ n ≤ 3; preferably, the silicon-containing compound is at least one of silicon tetrachloride, methyl dichlorosilane, dimethyl dichlorosilane, trimethyl chlorosilane, dimethyl chlorosilane; based on per mole of the alkoxymagnesium support, the amount of the silicon-containing compound used is 1 - 20 moles, preferably 1 - 5 moles.

[0023] According to some embodiments of the present invention, the ether compound is at least one of a lower aliphatic ether or an ether compound containing two or more ether groups; preferably, the ether compound is methyl ether, ethyl ether, propyl ether, butyl ether, pentyl ether, 1,1-bis(methoxymethyl)cyclopentadiene, propylene oxide, tetrahydrofuran, methyl tert-butyl ether, 1,4-dioxane, 9,9-bis(methoxymethyl)fluorene; preferably, the ether compound is the cyclic ether 1,4-dioxane containing two ether groups; based on per mole of the alkoxymagnesium carrier, the dosage of the ether compound is 0.01 - 2 moles, preferably 0.1 - 1.5 moles.

[0024] According to some embodiments of the present invention, the time of ultrasonic treatment is 0.1 - 1.5 hours, and the ultrasonic frequency is 20 KHz.

[0025] According to the third aspect of the present invention, there is provided an alkoxymagnesium carrier polyethylene catalyst, which comprises the main agent of the alkoxymagnesium carrier polyethylene catalyst as described above and a catalyst activator, and the catalyst activator is an organoaluminum compound.

[0026] According to some embodiments of the present invention, the organoaluminum compound is a chlorine-containing organoaluminum compound, and the chlorine-containing organoaluminum compound is dialkylaluminum monochloride with the chemical structural formula of R2AlCl or alkylaluminum sesquichloride with the chemical structural formula of R3Al2Cl3, wherein R is the same or different alkyl groups containing 1 - 5 carbon atoms.

[0027] According to some embodiments of the present invention, the organoaluminum compound is a chlorine-free organoaluminum compound, and the chlorine-free organoaluminum compound is trialkylaluminum AlR4 or dihydroalkylaluminum AlR42H, wherein R4 represents an alkyl group having 1 - 16 carbon atoms.

[0028] According to some embodiments of the present invention, based on per mole of the alkoxymagnesium carrier, the dosage of the catalyst activator is 0.01 - 2 moles, preferably 0.02 - 0.2 moles.

[0029] According to the fourth aspect of the present invention, there is provided a preparation method of the alkoxymagnesium carrier polyethylene catalyst as described above, which comprises: adding the catalyst activator to the main agent, and after activation at 20 - 40 °C, obtaining a catalyst slurry or obtaining a solid catalyst after drying.

[0030] By adopting the above technical solutions, the present invention has the following advantages compared with the prior art:

[0031] The main agent of the alkoxymagnesium-supported catalyst provided by the present invention is obtained by loading a titanium halide and an aryl ester compound on an alkoxymagnesium support, which helps to improve the performance of the catalyst, especially the activity of the catalyst. The titanium halide provides the active component of the catalyst. After adding the aryl ester compound, the two will react or complex, which will not only improve the activity of the catalyst, but also change the aggregation state. The particle morphology of the polymer directly replicates the particle morphology of the catalyst. The more compact and regular the catalyst aggregates, the higher the bulk density of the polymer prepared by the catalyst.

[0032] The preparation method of the main agent of the alkoxymagnesium-supported catalyst provided by the present invention can effectively improve the particle morphology of the main agent, control the particle size within 3-6 microns, and can regulate the particle size. The polymerization reaction is stable and easy to control.

[0033] The alkoxymagnesium-supported catalyst provided by the present invention constitutes a catalytic system together with a catalyst activator. Only a small amount of activator is required to obtain a highly active olefin polymerization catalyst; the catalyst provided by the present invention is particularly suitable for the slurry polymerization process; using the catalyst of the present invention to carry out ethylene slurry polymerization reaction at 0.7 MPa and 70 °C for 2 hours, the polymerization activity of the catalyst can reach 40,000 gPE / gCat, which can be used to develop ultra-high molecular weight polyethylene products with higher ash content requirements; the ultra-high molecular weight polyethylene product prepared by using the catalyst of the present invention has a higher bulk density, and the bulk density is 0.40-0.48 g / cm 3 , the average diameter of the polymer particles is in the range of 75-200 μm, and the viscosity-average molecular weight of the polymerization product can be accurately controlled within 1.5-10 million. Detailed embodiments

[0034] It should be understood that the embodiments of the present invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments of the present invention have been described in detail, those skilled in the art can easily understand that various modifications are feasible without substantially departing from the teachings of the subject matter of the present invention. Accordingly, all such modifications should be included within the scope of the present invention. Without departing from the gist of the present invention, other substitutions, modifications, changes and deletions can be made to the design, operating conditions and parameters of the following exemplary embodiments.

[0035] According to a first aspect of the present invention, there is provided a main agent of an alkoxymagnesium-supported polyethylene catalyst, which is composed of an alkoxymagnesium support loaded with a titanium halide and an aryl ester compound.

[0036] Preferably, the chemical structural formula of the alkoxymagnesium support is Mg(OR1)(OR2), where R1 and R2 are both alkyl groups containing 2-10 carbon atoms, such as ethyl, propyl, butyl, isopropyl, isobutyl, pentyl, octyl, etc., and preferably R1 and R2 are both ethyl groups.

[0037] Preferably, the alkoxymagnesium carrier is a quasi-spherical particle with an average particle size of 20 - 1500 μm and a bulk density of 0.30 - 0.40 g / cm 3 . Preferably, the average particle size of the alkoxymagnesium carrier is 200 - 700 μm and the bulk density is 0.32 - 0.38 g / cm 3 .

[0038] Preferably, the aryl ester compound is one or a mixture of di-n-butyl phthalate, diisobutyl phthalate, 1,3-dipentyl phthalate, methyl phenylacetate, ethyl benzoate, 1,3-butanediol dimethylbenzoate, 2,3-dimethyl-1,3-butanediol dibenzoate, phenethyl acrylate, phenyl methacrylate, 2-phenylethyl acrylate, 2,4-pentanediol dibenzoate, 2-methyl-3,5-heptanediol dibenzoate, 2,4-pentanediol dibenzoate, 4-ethyl-3,5-heptanediol dibenzoate. Based on per mole of the alkoxymagnesium carrier, the dosage of the aryl ester compound is 0.1 - 100 moles, preferably 0.3 - 30 moles. Typically but not restrictively, the dosage of the aryl ester compound can be 0.1 mole, 0.3 mole, 1 mole, 10 moles, 20 moles, 30 moles, 40 moles, 50 moles, 60 moles, 70 moles, 80 moles, 90 moles, 100 moles.

[0039] Preferably, the titanium-containing halide is at least one selected from the general formula (R1O)aTi(OR2)b(OR3)cXd, where a, b, c are integers between 0 and 4, d is an integer between 1 and 4, and a + b + c + d = 4, and R1, R2, R3 are hydrogen and / or alkyl, and X is at least one of chlorine and bromine. Preferably, the titanium-containing halide is at least one selected from titanium tetrachloride, titanium tetrabromide, chloro-triethoxy titanium, dichloro-diethoxy titanium, trichloro-ethoxy titanium, triisopropoxy titanium chloride. Based on per mole of the alkoxymagnesium carrier, the dosage of the titanium-containing halide is 0.1 - 40 moles, preferably 1 - 20 moles. Typically but not restrictively, the dosage of the titanium-containing halide can be 0.1 mole, 0.5 mole, 1 mole, 5 moles, 10 moles, 15 moles, 20 moles, 30 moles, 40 moles.

[0040] According to the second aspect of the present invention, there is provided a method for preparing the main agent of the alkoxymagnesium carrier polyethylene catalyst as described above, which comprises the following steps:

[0041] (1) Under the protection of an inert gas, disperse the alkoxymagnesium carrier in an inert organic hydrocarbon organic solvent, and then add an organic alcohol, and stir and heat to 50 - 100 °C. Dispersing in the organic hydrocarbon organic solvent is to make the alkoxymagnesium carrier better dispersed and for heat transfer. Adding a very small amount of organic alcohol is to control the particle size of the catalyst.

[0042] (2) Add electron donor I (including aryl ester compounds) to the alkoxymagnesium carrier dispersion obtained in step (1), and then slowly heat it to 60 - 150 °C (for example, 2 - 5 hours) to form a solution. After reaching the temperature, continue stirring and reacting for 1 - 4 hours, and then naturally cool it to room temperature for standby. Adding aryl ester compounds as electron donors will react or complex with titanium halides, which can improve the activity of the catalyst while changing the aggregation state. The particle morphology of the polymer directly replicates the particle morphology of the catalyst. The more compact and regular the catalyst aggregates, the higher the bulk density of the polymer prepared by the catalyst.

[0043] (3) Preheat the titanium halide to 60 - 80 °C, and then slowly add the solution from step (2) dropwise to the titanium halide (for example, 2 - 5 hours). After the addition is completed, react for another 0.5 - 2 hours to obtain a suspension. The titanium halide is the main active component of the catalyst.

[0044] (4) Cool the suspension formed in step (3) to 0 - 40 °C, add a silicon-containing compound, and stir and react for 0.5 - 4 hours to form a catalyst intermediate. The silicon-containing compound has two functions. One is to improve the catalyst activity, and the other is to reduce the content of Mg and Ti metals in the catalyst. This is because Si atoms will coordinate with the carrier and occupy the positions of Ti and Mg atoms, thereby reducing the content of Mg and Ti.

[0045] (5) Transfer the catalyst intermediate formed in step (4) to an ultrasonic treatment device and perform ultrasonic treatment for 0.1 - 1.5 hours. The ultrasonic frequency is 20 KHz. The main function of ultrasonic treatment is to improve the particle morphology of the catalyst, help reduce the agglomeration phenomenon of catalyst particles, and make their particle morphology more spherical.

[0046] (6) After ultrasonic treatment, raise the temperature to 40 - 80 °C, and add electron donor II during the heating process or after reaching the temperature for reaction. After reaching the temperature, stir and react for 0.5 - 4 hours. The role of adding electron donor II is to react or complex with titanium halides to further improve the particle morphology of the catalyst and increase the number of its active centers.

[0047] (6) Wash with an organic solvent and adjust the number of washing times according to the titanium content in the required catalyst to obtain the main agent. This step is to wash away the free and excessive titanium ions in the catalyst slurry.

[0048] Among them, in some embodiments, the inert gas protection can be nitrogen protection.

[0049] In step (1), the typical but non-limiting stirring and heating temperatures are 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C.

[0050] In step (2), the slow heating time is typically but not limited to 2 hours, 3 hours, 4 hours, 5 hours, and the heating temperature is typically but not limited to 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C. The stirring reaction time is typically but not limited to 1 hour, 2 hours, 3 hours, 4 hours.

[0051] In step (3), the preheating temperature is typically but not limited to 60°C, 70°C, 80°C, the slow heating time is typically but not limited to 2 hours, 3 hours, 4 hours, 5 hours, and the further reaction time is typically but not limited to 0.5 hour, 1 hour, 1.5 hours, 2 hours.

[0052] In step (4), the temperature reduction temperature is typically but not limited to 0°C, 10°C, 20°C, 30°C, 40°C, and the stirring reaction time is typically but not limited to 0.5 hour, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours.

[0053] In step (5), the ultrasonic treatment time is typically but not limited to 0.1 hour, 0.5 hour, 1 hour, 1.5 hours.

[0054] In step (6), the temperature increase temperature is typically but not limited to 40°C, 50°C, 60°C, 70°C, 80°C, and the stirring reaction time is typically but not limited to 0.5 hour, 1 hour, 2 hours, 3 hours, 4 hours.

[0055] Preferably, the inert hydrocarbon organic solvent includes aliphatic hydrocarbons such as hexane, heptane, octane, decane, pentane, dodecane, tetradecane, etc.; cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, methylcyclopentane, cyclooctane, etc.; aromatic hydrocarbons such as benzene, toluene, o-xylene, p-xylene, etc. Decane and toluene are preferred. When in use, the alkoxymagnesium carrier is dispersed in the inert hydrocarbon organic solvent and used as a dispersant. The amount of the inert hydrocarbon organic solvent is not particularly important. Calculated based on per mole of the alkoxymagnesium carrier, the amount of the inert hydrocarbon organic solvent is preferably 4 - 40 moles. Typically but not limited to, the amount of the inert hydrocarbon organic solvent can be 4 moles, 10 moles, 15 moles, 20 moles, 25 moles, 30 moles, 35 moles, 40 moles.

[0056] Organic alcohols are used for surface modification of the magnesium alkoxide support, which is more conducive to the uniform loading of subsequent titanium halides. Preferably, the organic alcohol includes at least one of linear alcohols or isomeric alcohols having 1 to 20 carbon atoms, such as methanol, ethanol, propanol, butanol, isopropanol, ethylene glycol, glycerol, cyclohexanol, decanol, isooctanol, dodecanol, 1,4-pentanediol, 1,5-pentanediol, 1,3-butanediol, etc., and isooctanol and ethylene glycol are preferred. The amount of the organic alcohol is very small. Based on per mole of the magnesium alkoxide support, the amount of the organic alcohol is preferably 0.02 to 0.2 mole, and more preferably 0.05 to 0.1 mole. Typically but not restrictively, the amount of the organic alcohol can be 0.02 mole, 0.03 mole, 0.04 mole, 0.05 mole, 0.06 mole, 0.07 mole, 0.08 mole, 0.09 mole, 0.10 mole, 0.11 mole, 0.12 mole, 0.13 mole, 0.14 mole, 0.15 mole, 0.16 mole, 0.17 mole, 0.18 mole, 0.19 mole, 0.20 mole.

[0057] Preferably, the silicon-containing compound has the structure of R n SiCl 4-n (0 ≤ n ≤ 3), where R is an alkyl group, hydrogen, or an oxygen-containing group. Representative compounds include silicon tetrachloride, methyl dichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and dimethylchlorosilane. Based on per mole of the magnesium alkoxide support, the amount of the silicon-containing compound is 1 to 20 moles, preferably 1 to 5 moles. Typically but not restrictively, the amount of the silicon-containing compound can be 1 mole, 2 moles, 3 moles, 4 moles, 5 moles, 10 moles, 15 moles, 20 moles.

[0058] Preferably, the electron donor II is an ether compound, including a lower aliphatic ether or one or a mixture of ether compounds containing two or more ether groups, such as methyl ether, ethyl ether, propyl ether, butyl ether, pentyl ether, 1,1-bis(methoxymethyl)cyclopentadiene, propylene oxide, tetrahydrofuran, methyl tert-butyl ether, 1,4-dioxane, 9,9-bis(methoxymethyl)fluorene, and 1,4-dioxane, a cyclic ether containing two ether groups, is preferred. Based on per mole of the magnesium alkoxide support, the amount of the electron donor II is 0.01 to 2 moles, preferably 0.1 to 1.5 moles. Typically but not restrictively, the amount of the electron donor II can be 0.01 mole, 0.05 mole, 0.1 mole, 0.5 mole, 1 mole, 1.5 mole, 2 moles.

[0059] The ultrasonic treatment device converts industrial frequency electricity into high-frequency electrical signals above 20KHz and transports them to the transducer through a high-frequency cable. The transducer can convert electrical energy into powerful ultrasonic vibrations. When ultrasonic waves are added to the catalyst preparation process, it helps to reduce the agglomeration of catalyst particles, make their dispersion more uniform, break the originally agglomerated particles, so that the particle size of the catalyst is more uniform and the generation of large catalyst particles is reduced.

[0060] According to the third aspect of the present invention, there is provided a magnesium alkoxide-supported polyethylene catalyst, which catalyst comprises components (A) and (B), wherein component (A) is the main agent as described above, and component (B) is a catalyst activator. Component (B) is an organoaluminum compound.

[0061] As the organoaluminum compound of component (B), a chlorine-containing organoaluminum compound can be used, such as dialkylaluminum monochloride with the chemical structural formula R2AlCl or alkylaluminum sesquichloride with the chemical structural formula R3Al2Cl3, wherein R is the same or different alkyl groups containing 1-5 carbon atoms. Representative compounds include (CH3)2AlCl, CH3AlCl2, EtAlCl2, Et2AlCl, Bu2AlCl, Pr2AlCl, etc., and at least one of (CH3)2AlCl and CH3AlCl2 is preferred.

[0062] As the organoaluminum compound of component (B), a chlorine-free compound can also be used. Suitable for use as the chlorine-free compound is trialkylaluminum AlR4 or dialkylaluminum hydride AlR42H. In these formulas, R4 represents an alkyl group having 1 to 16 carbon atoms. Representative compounds include Al(C2H5)3, Al(C2H5)2H, Al(C3H7)3, Al(C3H7)2H, Al(iso-C4H9)2H, Al(iso-C4H9)3, and one or a mixture of these compounds can be used.

[0063] Preferably, based on each mole of the magnesium alkoxide support, the dosage of component (B) is 0.01 - 2 moles, preferably 0.02 - 0.2 moles. Typically but not restrictively, the dosage of component (B) can be 0.01 mole, 0.02 mole, 0.05 mole, 0.1 mole, 0.2 mole, 0.5 mole, 1 mole, 1.5 moles, 2 moles.

[0064] According to the fourth aspect of the present invention, there is provided a method for preparing a magnesium alkoxide-supported polyethylene catalyst as described above, which comprises: adding component (B) to component (A), and after activation at 20 - 40°C, obtaining a catalyst slurry or obtaining a solid catalyst after drying.

[0065] The alkoxymagnesium supported catalyst prepared by the present invention has good particle morphology, with a relatively small catalyst particle size, an average particle size of 3 - 6 μm, and the particle size can be regulated. The catalyst has high activity, the polymerization reaction is stable, and the polymerization reaction is easy to control.

[0066] The alkoxymagnesium supported catalyst prepared by the present invention needs to form a catalytic system together with an activator, and a very small amount of activator can be used to obtain a highly active olefin polymerization catalyst.

[0067] The catalyst of the present invention is particularly suitable for the slurry polymerization process. The catalyst has relatively high activity. Using the catalyst of the present invention to carry out ethylene slurry polymerization reaction at 0.7 MPa and 70 °C for 2 hours, the polymerization activity of the catalyst can reach 40,000 gPE / gCat, and it can be used to develop ultra-high molecular weight polyethylene products with relatively high requirements for ash content.

[0068] The ultra-high molecular weight polyethylene product prepared by using the catalyst of the present invention has a relatively high bulk density, with a bulk density of 0.40 - 0.48 g / cm 3 , the average diameter of the polymer particles is 75 - 200 μm, and the viscosity-average molecular weight of the polymerization product can be accurately controlled within the range of 1.5 - 10 million.

[0069] The above technical solutions of the present invention will be described in detail below through specific examples.

[0070] The test methods for the catalyst performance and the polymer molecular weight in the examples are as follows:

[0071] The activity of the catalyst: It refers to the ratio of the total mass of the polyethylene obtained by polymerization to the amount of the catalyst added.

[0072] Determination of the viscosity-average molecular weight of the product: The viscosity-average molecular weight of the polymer is mainly measured by an Ubbelohde viscometer, and the molecular weight is determined according to GB - ASTMD4020 - 81. A certain amount of UHMWPE powder is dissolved in a decalin solution, and the efflux times of the pure decalin solution and the decalin solution containing UHMWPE are measured with an Ubbelohde viscometer at 135 °C.

[0073] [η] = K × M α

[0074]

[0075]

[0076] η sp = η [e] -1

[0077]

[0078] Where: t - the efflux time of a decalin / UHMWPE mixed solution at a certain concentration from an Ubbelohde viscometer, t0 - the efflux time of a pure decalin solution from an Ubbelohde viscometer, η sp - relative viscosity increment, η [e] - relative viscosity, C - sample concentration (g / ml), m - sample mass (g), S - room temperature correction value when adding decalin, [η] - intrinsic viscosity, K - proportionality constant, α - empirical constant, usually between 0.5 and 1, M - polymer viscosity-average molecular weight.

[0079] In the examples, the catalyst preparation device is a five-necked glass reaction device equipped with a heating and cooling system and equipped with temperature measurement, stirring device, nitrogen inlet, nitrogen outlet and feeding port, and the reaction situation inside the device can be observed.

[0080] Example 1:

[0081] Preparation of the catalyst:

[0082] Under nitrogen protection, 5 g of ethoxymagnesium, 0.34 ml of isooctanol, 34 ml of decane were added to the catalyst preparation device, and 3.5 ml of diisobutyl phthalate was added. It was heated to 150 °C for 3 hours and continued to stir and react at 150 °C for 2 hours. The system was cooled to room temperature, and the solution was uniformly added dropwise to 9.7 ml of titanium tetrachloride preheated to 60 °C at a rapid stirring speed of 800 r / min for 4 hours. After the addition was completed, the reaction was continued for 2 hours. The system was cooled to 10 °C, 5 ml of silicon tetrachloride was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonic-treated at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 3.8 ml of 1,4-dioxane was added for reaction for 1 hour. After washing with hexane, component (A) was obtained.

[0083] 0.12 ml of (CH3)2AlCl was added to component (A) for activation at 20 °C to obtain a catalyst slurry, and a solid catalyst powder was obtained after drying with nitrogen.

[0084] In this example, based on each mole of ethoxymagnesium, the dosage of isooctanol was 0.05 mol, the dosage of decane was 4 mol, the dosage of diisobutyl phthalate was 0.3 mol, the dosage of titanium tetrachloride was 2 mol, the dosage of silicon tetrachloride was 1 mol, the dosage of 1,4-dioxane was 1 mol, and the dosage of (CH3)2AlCl was 0.02 mol.

[0085] After testing with a laser particle size analyzer, the median particle size D50 of the catalyst was 3.74 μm.

[0086] Polymerization evaluation method 1:

[0087] The 2L stainless steel polymerization kettle is purged with nitrogen more than three times, and then the reaction system is purged with polymerization-grade ethylene gas more than three times. Then, 1L of n-hexane and 2ml of triethylaluminum or triisobutylaluminum with a certain concentration are added to the polymerization kettle. After starting the stirring, 3mg of the solid catalyst powder prepared in Example 1 is added. The polymerization kettle is heated to 50°C by a water bath, and ethylene is slowly introduced until the system pressure reaches 0.7MPa. The reaction pressure is kept constant, and the temperature is further raised to 70°C. After maintaining the polymerization reaction at 70°C for 2 hours, the temperature is lowered. After purging with nitrogen, the product is discharged and dried to obtain ultra-high molecular weight polyethylene.

[0088] Example 2:

[0089] Preparation of catalyst:

[0090] Under nitrogen protection, 5g of ethoxymagnesium, 0.34ml of isooctanol, 170ml of decane are added to the catalyst preparation device, and 1.84ml of methyl phenylacetate is added. The mixture is heated to 80°C for 2 hours and stirred at 80°C for another 1 hour. Then the system temperature is lowered to room temperature. Under rapid stirring at a stirring speed of 800r / min, the solution is uniformly added dropwise to 9.7ml of titanium tetrachloride preheated to 60°C over 4 hours. After the addition is completed, the reaction continues for 2 hours. The system temperature is lowered to 10°C, 5ml of silicon tetrachloride is added, and the mixture is stirred and reacted for 2 hours to form a catalyst intermediate. This catalyst intermediate is transferred to an ultrasonic treatment device and ultrasonic-treated at an ultrasonic frequency of 20KHz for 1 hour. After ultrasonic treatment, the system temperature is raised to 50°C, and 3.8ml of 1,4-dioxane is added for reaction for 1 hour. After washing with hexane, component (A) is obtained.

[0091] 0.2ml of (CH3)2AlCl is added to component (A) for activation at 40°C to obtain a catalyst slurry, which is dried with nitrogen to obtain a solid catalyst powder.

[0092] In this example, based on each mole of ethoxymagnesium, the dosage of isooctanol is 0.05mol, the dosage of decane is 20mol, the dosage of methyl phenylacetate is 0.3mol, the dosage of titanium tetrachloride is 2mol, the dosage of silicon tetrachloride is 1mol, the dosage of 1,4-dioxane is 1mol, and the dosage of (CH3)2AlCl is 0.03mol.

[0093] The polymerization evaluation is carried out in the same method as in Example 1.

[0094] Example 3:

[0095] Preparation of catalyst:

[0096] Under nitrogen protection, 5 g of magnesium ethoxide, 0.34 ml of isooctanol, 170 ml of decane were added to the catalyst preparation device, and 1.84 ml of methyl phenylacetate was added. It was heated to 80 °C for 2 hours and continuously stirred at 80 °C for 1 hour. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 800 r / min, the solution was uniformly added dropwise to 96 ml of titanium tetrachloride preheated to 60 °C over 4 hours. After the addition was completed, the reaction continued for 1 hour. The system was cooled to 10 °C, 5 ml of silicon tetrachloride was added, and the reaction was stirred for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonically treated at an ultrasonic frequency of 20 kHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added for reaction for 1 hour. After washing with hexane, component (A) was obtained.

[0097] 0.5 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, and a solid catalyst powder was obtained after drying with nitrogen.

[0098] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.05 mol, the dosage of decane was 20 mol, the dosage of methyl phenylacetate was 0.3 mol, the dosage of titanium tetrachloride was 20 mol, the dosage of silicon tetrachloride was 1 mol, the dosage of 1,4-dioxane was 0.5 mol, and the dosage of (CH3)2AlCl was 0.08 mol.

[0099] The polymerization evaluation was carried out in the same method as in Example 1.

[0100] Example 4:

[0101] Preparation of the catalyst:

[0102] Under nitrogen protection, 5 g of magnesium ethoxide, 0.34 ml of isooctanol, 170 ml of decane were added to the catalyst preparation device, and 1.84 ml of methyl phenylacetate was added. It was heated to 80 °C for 2 hours and continuously stirred at 80 °C for 1 hour. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 800 r / min, the solution was uniformly added dropwise to 24 ml of titanium tetrachloride preheated to 60 °C over 4 hours. After the addition was completed, the reaction continued for 1 hour. The system was cooled to 10 °C, 5 ml of silicon tetrachloride was added, and the reaction was stirred for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonically treated at an ultrasonic frequency of 20 kHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 5.6 ml of 1,4-dioxane was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0103] 1 mL of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0104] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.05 mol, the dosage of decane was 20 mol, the dosage of methyl phenylacetate was 0.3 mol, the dosage of titanium tetrachloride was 5 mol, the dosage of silicon tetrachloride was 1 mol, the dosage of 1,4-dioxane was 1.5 mol, and the dosage of (CH3)2AlCl was 0.16 mol.

[0105] The polymerization evaluation was carried out by the same method as in Example 1.

[0106] Example 5:

[0107] Preparation of catalyst:

[0108] Under nitrogen protection, 5 g of magnesium ethoxide, 0.34 mL of isooctanol, 340 mL of decane were added to the catalyst preparation device, and 3.9 mL of 1,3-dipentyl phthalate was added. It was heated to 110 °C for 2 hours and continuously stirred at 110 °C for 1 hour. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 24 mL of titanium tetrachloride preheated to 80 °C over 4 hours. After the addition was completed, the reaction continued for 1 hour. The system was cooled to 10 °C, 5 mL of silicon tetrachloride was added, and the reaction was stirred for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonic treated at an ultrasonic frequency of 20 KHz for 1 hour. After ultrasonic treatment, the system was heated to 50 °C, and 5.6 mL of 1,4-dioxane was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0109] 0.16 mL of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0110] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.05 mol, the dosage of decane was 40 mol, the dosage of 1,3-dipentyl phthalate was 0.3 mol, the dosage of titanium tetrachloride was 5 mol, the dosage of silicon tetrachloride was 1 mol, the dosage of 1,4-dioxane was 1.5 mol,

[0111] The dosage of (CH3)2AlCl was 0.03 mol.

[0112] The polymerization evaluation was carried out by the same method as in Example 1.

[0113] Example 6:

[0114] Preparation of catalyst:

[0115] Under nitrogen protection, 5 g of magnesium ethoxide, 0.55 ml of isooctanol, 340 ml of decane were added to the catalyst preparation device, and 39 ml of 1,3-dipentyl phthalate was added. It was heated to 110 °C for 2 hours and continuously stirred at 110 °C for 1 hour. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 48 ml of titanium tetrachloride preheated to 80 °C over 4 hours. After the addition was completed, the reaction continued for 1 hour. The system was cooled to 30 °C, 5 ml of silicon tetrachloride was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonically treated at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 5.6 ml of 1,4-dioxane was added and reacted for 4 hours. After washing with hexane, component (A) was obtained.

[0116] 1.1 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, and a solid catalyst powder was obtained after drying with nitrogen.

[0117] In this example, based on each mole of magnesium ethoxide, the dosage of isooctanol was 0.08 mol, the dosage of decane was 40 mol, the dosage of 1,3-dipentyl phthalate was 3 mol, the dosage of titanium tetrachloride was 10 mol, the dosage of silicon tetrachloride was 1 mol, the dosage of 1,4-dioxane was 1.5 mol, and the dosage of (CH3)2AlCl was 0.19 mol.

[0118] The catalyst addition amount was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0119] Example 7:

[0120] Preparation of catalyst:

[0121] Under nitrogen protection, 5 g of magnesium ethoxide, 0.55 ml of isooctanol, 340 ml of decane were added to the catalyst preparation device, and 39 ml of 1,3-dipentyl phthalate was added. The mixture was heated to 110 °C for 2 hours and continuously stirred at 110 °C for 1 hour. Then the system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 48 ml of titanium tetrachloride preheated to 80 °C over 4 hours. After the addition was completed, the reaction continued for 2 hours. The system was cooled to 30 °C, 5 ml of silicon tetrachloride was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonic-treated at an ultrasonic frequency of 20 kHz for 1 hour. After ultrasonic treatment, the system was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0122] 0.5 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0123] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.08 mol, the dosage of decane was 40 mol, the dosage of 1,3-dipentyl phthalate was 3 mol, the dosage of titanium tetrachloride was 10 mol, the dosage of silicon tetrachloride was 1 mol, the dosage of 1,4-dioxane was 0.4 mol, and the dosage of (CH3)2AlCl was 0.09 mol.

[0124] The catalyst addition amount was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0125] Example 8:

[0126] Preparation of the catalyst:

[0127] Under nitrogen protection, 5 g of magnesium ethoxide, 0.55 ml of isooctanol, 84 ml of decane were added to the catalyst preparation device, and 39 ml of 1,3-dipentyl phthalate was added. The mixture was heated to 110 °C for 3 hours and continuously stirred at 110 °C for 1 hour. Then the system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 48 ml of titanium tetrachloride preheated to 80 °C over 3 hours. After the addition was completed, the reaction continued for 1.5 hours. The system was cooled to 40 °C, 28 ml of trimethylchlorosilane was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonic-treated at an ultrasonic frequency of 20 kHz for 1 hour. After ultrasonic treatment, the system was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0128] 0.2 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0129] In this example, based on each mole of magnesium ethoxide, the amount of isooctanol used was 0.08 mol, the amount of decane used was 10 mol, the amount of 1,3-dipentyl phthalate used was 3 mol, the amount of titanium tetrachloride used was 10 mol, the amount of trimethylchlorosilane used was 5 mol, the amount of 1,4-dioxane used was 0.4 mol, and the amount of (CH3)2AlCl used was 0.03 mol.

[0130] The amount of catalyst added was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0131] Example 9:

[0132] Preparation of catalyst:

[0133] Under nitrogen protection, 5 g of magnesium ethoxide, 0.55 ml of isooctanol, and 84 ml of decane were added to a catalyst preparation device, and 39 ml of 1,3-dipentyl phthalate was added. The mixture was heated to 120 °C for 3 hours and stirred at 180 °C for 1 hour. Then the system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 48 ml of triethoxychlorotitanium preheated to 80 °C over 3 hours. After the addition was completed, the reaction continued for 1 hour. The system was cooled to 40 °C, 5.6 ml of trimethylchlorosilane was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and treated ultrasonically at an ultrasonic frequency of 20 KHz for 1 hour. After ultrasonic treatment, the system was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added and reacted for 4 hours. After washing with hexane, component (A) was obtained.

[0134] 0.3 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0135] In this example, based on each mole of magnesium ethoxide, the amount of isooctanol used was 0.08 mol, the amount of decane used was 10 mol, the amount of 1,3-dipentyl phthalate used was 3 mol, the amount of triethoxychlorotitanium used was 10 mol, the amount of trimethylchlorosilane used was 1 mol, the amount of 1,4-dioxane used was 0.4 mol, and the amount of (CH3)2AlCl used was 0.05 mol.

[0136] The amount of catalyst added was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0137] Example 10:

[0138] Preparation of catalyst:

[0139] Under nitrogen protection, 5 g of magnesium ethoxide, 0.55 ml of isooctanol, 84 ml of decane were added to the catalyst preparation device, and 1.9 ml of ethyl benzoate was added. The mixture was heated to 150 °C for 3 hours and stirred at 150 °C for 1 hour. Then the system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 25 ml of titanium trichloride triethoxide preheated to 70 °C over 3 hours. After the addition was completed, the reaction was continued for 1 hour. The system was cooled to 40 °C, 28 ml of trimethylchlorosilane was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonically treated at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added and reacted for 4 hours. After washing with hexane, component (A) was obtained.

[0140] 0.2 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, and a solid catalyst powder was obtained after drying with nitrogen.

[0141] In this example, based on per mole of magnesium ethoxide, the amount of isooctanol used was 0.08 mol, the amount of decane used was 10 mol, the amount of ethyl benzoate used was 0.3 mol, the amount of titanium trichloride triethoxide used was 5.2 mol, the amount of trimethylchlorosilane used was 5 mol, the amount of 1,4-dioxane used was 0.4 mol, and the amount of (CH3)2AlCl used was 0.03 mol.

[0142] The amount of catalyst added was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0143] Example 11:

[0144] Preparation of catalyst:

[0145] Under nitrogen protection, 5 g of magnesium ethoxide, 0.55 ml of isooctanol, 160 ml of decane were added to the catalyst preparation device, and 20 ml of ethyl benzoate was added. It was heated to 150 °C for 3 hours and continued to stir and react at 150 °C for 1 hour. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 25 ml of titanium trichloroethoxide preheated to 60 °C over 5 hours. After the addition was completed, the reaction continued for 0.5 hour. The system was cooled to 20 °C, 28 ml of trimethylchlorosilane was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonic-treated at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0146] 0.18 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, and a solid catalyst powder was obtained after drying with nitrogen.

[0147] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.08 mol, the dosage of decane was 18.8 mol, the dosage of ethyl benzoate was 3.2 mol, the dosage of titanium trichloroethoxide was 5.2 mol, the dosage of trimethylchlorosilane was 5 mol, the dosage of 1,4-dioxane was 0.4 mol, and the dosage of (CH3)2AlCl was 0.03 mol.

[0148] The catalyst addition amount was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0149] Example 12:

[0150] Preparation of the catalyst:

[0151] Under nitrogen protection, 5 g of magnesium ethoxide, 0.68 ml of isooctanol, 160 ml of decane were added to the catalyst preparation device, and 188 ml of ethyl benzoate was added. It was heated to 150 °C for 4 hours and continued to stir and react at 150 °C for 1 hour. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 400 r / min, the solution was uniformly added dropwise to 25 ml of titanium trichloroethoxide preheated to 60 °C over 2 hours. After the addition was completed, the reaction continued for 0.5 hour. The system was cooled to 20 °C, 28 ml of trimethylchlorosilane was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonic-treated at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0152] 0.7 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0153] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.1 mol, the dosage of decane was 18.8 mol, the dosage of ethyl benzoate was 30 mol, the dosage of titanium trichloride triethoxide was 5.2 mol, the dosage of trimethylchlorosilane was 5 mol, the dosage of 1,4-dioxane was 0.4 mol, and the dosage of (CH3)2AlCl was 0.12 mol.

[0154] The amount of catalyst added was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0155] Example 13:

[0156] Preparation of catalyst:

[0157] Under nitrogen protection, 5 g of magnesium ethoxide, 0.68 ml of isooctanol, 160 ml of decane were added to the catalyst preparation device, and 3.6 ml of 2,4-pentanediol dibenzoate was added. The mixture was heated to 150 °C for 4 hours and continued to stir and react at 180 °C for 2 hours. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 600 r / min, the solution was uniformly added dropwise to 48 ml of titanium tetrachloride preheated to 75 °C over 2 hours. After the addition was completed, the reaction continued for 0.5 hour. The system was cooled to 20 °C, 28 ml of trimethylchlorosilane was added, and the mixture was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonic-treated at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 1.9 ml of 1,4-dioxane was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0158] 0.8 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0159] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.1 mol, the dosage of decane was 18.8 mol, the dosage of 2,4-pentanediol dibenzoate was 0.3 mol, the dosage of titanium tetrachloride was 10 mol, the dosage of trimethylchlorosilane was 5 mol, the dosage of 1,4-dioxane was 0.4 mol, and the dosage of (CH3)2AlCl was 0.14 mol.

[0160] The amount of catalyst added was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0161] Example 14:

[0162] Preparation of the catalyst:

[0163] Under nitrogen protection, 5 g of magnesium ethoxide, 0.68 ml of isooctanol, 160 ml of decane were added to the catalyst preparation device, and 7.5 ml of phenethyl acrylate was added. It was heated to 120 °C for 4 hours, and the reaction was continued with stirring at 120 °C for 4 hours. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 600 r / min, the solution was uniformly added dropwise to 48 ml of titanium tetrachloride preheated to 75 °C over 2 hours. After the addition was completed, the reaction was continued for 2 hours. The system was cooled to 10 °C, 4.8 ml of dimethylchlorosilane was added, and the reaction was stirred for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and subjected to ultrasonic treatment at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 11.3 ml of butyl ether was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0164] 0.9 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, and a solid catalyst powder was obtained after drying with nitrogen.

[0165] In this example, based on each mole of magnesium ethoxide, the dosage of isooctanol was 0.1 mol, the dosage of decane was 18.8 mol, the dosage of phenethyl acrylate was 1 mol, the dosage of titanium tetrachloride was 10 mol, the dosage of dimethylchlorosilane was 1 mol, the dosage of butyl ether was 1.5 mol, and the dosage of (CH3)2AlCl was 0.16 mol.

[0166] The catalyst addition amount was 1.8 mg, and the other polymerization evaluation conditions were the same as those in Example 1.

[0167] Example 15:

[0168] Preparation of the catalyst:

[0169] Under nitrogen protection, 5 g of magnesium ethoxide, 0.68 ml of isooctanol, 160 ml of decane were added to the catalyst preparation device, and 3.4 ml of phenyl methacrylate was added. It was heated to 150 °C for 4 hours and continued to stir and react at 160 °C for 1 hour. The system was cooled to room temperature. Under rapid stirring at a stirring speed of 600 r / min, the solution was uniformly added dropwise to 20 ml of titanium tetrabromide preheated to 70 °C over 3 hours. After the addition was completed, the reaction continued for 2 hours. The system was cooled to 20 °C, 25 ml of silicon tetrachloride was added, and it was stirred and reacted for 2 hours to form a catalyst intermediate. The catalyst intermediate was transferred to an ultrasonic treatment device and ultrasonically treated at an ultrasonic frequency of 20 KHz for 1 hour. The system after ultrasonic treatment was heated to 50 °C, and 11.3 ml of dibutyl ether was added for reaction for 4 hours. After washing with hexane, component (A) was obtained.

[0170] 0.2 ml of (CH3)2AlCl was added to component (A) and activated at 40 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder.

[0171] In this example, based on per mole of magnesium ethoxide, the dosage of isooctanol was 0.1 mol, the dosage of decane was 18.8 mol, the dosage of phenyl methacrylate was 0.5 mol, the dosage of titanium tetrabromide was 4 mol, the dosage of silicon tetrachloride was 5 mol, the dosage of dibutyl ether was 1.5 mol, and the dosage of (CH3)2AlCl was 0.03 mol.

[0172] The catalyst addition amount was 1.8 mg, and the other polymerization evaluation conditions were the same as those in Example 1.

[0173] Example 16:

[0174] The preparation method of component (A) was the same as that in Example 1.

[0175] 0.2 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, based on per mole of magnesium ethoxide, the dosage of Al(C2H5)3 was 0.03 mol.

[0176] The catalyst addition amount was 2 mg, and the other polymerization evaluation conditions were the same as those in Example 1.

[0177] Example 17:

[0178] The preparation method of component (A) was the same as that in Example 2.

[0179] 0.3 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, the dosage of Al(C2H5)3 was 0.05 mol per mole of magnesium ethoxide.

[0180] The catalyst addition amount was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0181] Example 18:

[0182] The preparation method of component (A) was the same as that in Example 3.

[0183] 0.4 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, the dosage of Al(C2H5)3 was 0.07 mol per mole of magnesium ethoxide.

[0184] The catalyst addition amount was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0185] Example 19:

[0186] The preparation method of component (A) was the same as that in Example 4.

[0187] 0.5 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, the dosage of Al(C2H5)3 was 0.09 mol per mole of magnesium ethoxide.

[0188] The catalyst addition amount was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0189] Example 20:

[0190] The preparation method of component (A) was the same as that in Example 5.

[0191] 0.6 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, the dosage of Al(C2H5)3 was 0.1 mol per mole of magnesium ethoxide.

[0192] The catalyst addition amount was 2 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0193] Example 21:

[0194] The preparation method of component (A) was the same as that in Example 1.

[0195] 0.3 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, based on every mole of magnesium ethoxide, the dosage of Al(C2H5)3 was 0.05 mol.

[0196] The catalyst addition amount was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0197] Example 22:

[0198] The preparation method of component (A) was the same as that in Example 2.

[0199] 0.2 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, based on every mole of magnesium ethoxide, the dosage of Al(C2H5)3 was 0.03 mol.

[0200] The catalyst addition amount was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0201] Example 23:

[0202] The preparation method of component (A) was the same as that in Example 3.

[0203] 0.4 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, based on every mole of magnesium ethoxide, the dosage of Al(C2H5)3 was 0.07 mol.

[0204] The catalyst addition amount was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0205] Example 24:

[0206] The preparation method of component (A) was the same as that in Example 4.

[0207] 0.5 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry, which was dried with nitrogen to obtain a solid catalyst powder. Among them, based on every mole of magnesium ethoxide, the dosage of Al(C2H5)3 was 0.09 mol.

[0208] The catalyst addition amount was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0209] Example 25:

[0210] The preparation method of component (A) was the same as that in Example 5.

[0211] 0.2 ml of Al(C2H5)3 was added to component (A) and activated at 30 °C to obtain a catalyst slurry. After drying with nitrogen, a solid catalyst powder was obtained. Among them, the dosage of Al(C2H5)3 was 0.03 mol per mole of ethoxymagnesium.

[0212] The catalyst addition amount was 1.8 mg, and other polymerization evaluation conditions were the same as those in Example 1.

[0213] Example 26:

[0214] The catalyst preparation method was the same as that in Example 1.

[0215] Polymerization evaluation method 2:

[0216] The 2 L stainless steel polymerization kettle was purged with nitrogen more than three times, and then purged with polymerization-grade ethylene gas more than three times. Then, 1 L of n-hexane and 2 ml of triethylaluminum or triisobutylaluminum with a certain concentration were added to the polymerization kettle. After starting stirring, 1.8 mg of the solid catalyst powder prepared in Example 1 was added. The polymerization kettle was heated to 50 °C by a water bath, and ethylene was slowly introduced until the system pressure reached 0.7 MPa. The reaction pressure was kept constant, and the temperature was further raised to 65 °C. After maintaining the polymerization reaction at 65 °C for 2 hours, the temperature was lowered. After purging with nitrogen, the product was discharged and dried to obtain an ultra-high molecular weight polyethylene product.

[0217] Example 27:

[0218] The catalyst preparation method was the same as that in Example 2.

[0219] Polymerization evaluation method 2 was adopted, and the polymerization evaluation method was the same as that in Example 26.

[0220] Example 28:

[0221] The catalyst preparation method was the same as that in Example 3.

[0222] Polymerization evaluation method 2 was adopted, and the polymerization evaluation method was the same as that in Example 26.

[0223] Example 29:

[0224] The catalyst preparation method was the same as that in Example 4.

[0225] Polymerization evaluation method 2 was adopted, and the polymerization evaluation method was the same as that in Example 26.

[0226] Example 30:

[0227] The catalyst preparation method was the same as that in Example 5.

[0228] Polymerization evaluation method 2 was adopted, and the polymerization evaluation method was the same as that in Example 26.

[0229] Example 31:

[0230] The preparation method of the catalyst is the same as that of Example 1.

[0231] Polymerization evaluation method 3 is adopted:

[0232] The 2L stainless steel polymerization kettle is purged with nitrogen for more than three times, and then purged with polymerization-grade ethylene gas for more than three times. Then, 1L of n-hexane and 2ml of triethylaluminum or triisobutylaluminum with a certain concentration are added to the polymerization kettle. After starting the stirring, 1.5mg of the solid catalyst powder prepared in Example 1 is added. The polymerization kettle is heated to 50°C by a water bath, and ethylene is slowly introduced until the system pressure reaches 0.7MPa. The reaction pressure is kept constant, and the temperature is further raised to 62°C. After maintaining the polymerization reaction at 62°C for 2 hours, the temperature is lowered. After purging with nitrogen, the product is discharged and dried to obtain an ultra-high molecular weight polyethylene product.

[0233] Example 32:

[0234] The preparation method of the catalyst is the same as that of Example 2.

[0235] Polymerization evaluation method 3 is adopted:

[0236] Polymerization evaluation method 3 is adopted, and the polymerization evaluation method is the same as that of Example 31.

[0237] Example 33:

[0238] The preparation method of the catalyst is the same as that of Example 3.

[0239] Polymerization evaluation method 3 is adopted, and the polymerization evaluation method is the same as that of Example 31.

[0240] Example 34:

[0241] The preparation method of the catalyst is the same as that of Example 4.

[0242] Polymerization evaluation method 3 is adopted, and the polymerization evaluation method is the same as that of Example 31.

[0243] Example 35:

[0244] The preparation method of the catalyst is the same as that of Example 5.

[0245] Polymerization evaluation method 3 is adopted, and the polymerization evaluation method is the same as that of Example 31.

[0246] Example 36:

[0247] The preparation method of the catalyst is the same as that of Example 1.

[0248] Polymerization evaluation method 4 is adopted:

[0249] The 2L stainless steel polymerization kettle is purged with nitrogen for more than three times, and then purged with polymerization-grade ethylene gas for more than three times. Then, 1L of n-hexane and 2ml of triethylaluminum or triisobutylaluminum with a certain concentration are added to the polymerization kettle. After starting the stirring, 1.2mg of the solid catalyst powder prepared in Example 1 is added. The polymerization kettle is heated to 50°C through a water bath, and ethylene is slowly introduced until the system pressure reaches 0.66MPa. The reaction pressure is kept constant, and the temperature is further raised to 62°C. After maintaining the polymerization reaction at 62°C for 2 hours, the temperature is lowered. After purging with nitrogen, the product is discharged and dried to obtain ultra-high molecular weight polyethylene.

[0250] Example 37:

[0251] The preparation method of the catalyst is the same as that in Example 2.

[0252] Polymerization evaluation method 4 is adopted, and the polymerization evaluation method is the same as that in Example 36.

[0253] Example 38:

[0254] The preparation method of the catalyst is the same as that in Example 3.

[0255] Polymerization evaluation method 4 is adopted, and the polymerization evaluation method is the same as that in Example 36.

[0256] Example 39:

[0257] The preparation method of the catalyst is the same as that in Example 4.

[0258] Polymerization evaluation method 4 is adopted, and the polymerization evaluation method is the same as that in Example 36.

[0259] Example 40:

[0260] The preparation method of the catalyst is the same as that in Example 5.

[0261] Polymerization evaluation method 4 is adopted, and the polymerization evaluation method is the same as that in Example 36.

[0262] Example 41:

[0263] The preparation method of the catalyst is the same as that in Example 1.

[0264] Polymerization evaluation method 5 is adopted:

[0265] The 2L stainless steel polymerization kettle is purged with nitrogen for more than three times, and then purged with polymerization-grade ethylene gas for more than three times. Then, 1L of n-hexane and 2ml of triethylaluminum or triisobutylaluminum with a certain concentration are added to the polymerization kettle. After starting the stirring, 1.0mg of the solid catalyst powder prepared in Example 1 is added. The polymerization kettle is heated to 50°C by a water bath, ethylene is slowly introduced until the system pressure reaches 0.64MPa, the reaction pressure is kept constant, and the temperature is further raised to 60°C. After maintaining the polymerization reaction at 60°C for 2 hours, the temperature is lowered, and after purging with nitrogen, the product is discharged and dried to obtain an ultra-high molecular weight polyethylene product.

[0266] Example 42:

[0267] The preparation method of the catalyst is the same as that of Example 2.

[0268] Polymerization evaluation method 5 is adopted, and the polymerization evaluation method is the same as that of Example 41.

[0269] Example 43:

[0270] The preparation method of the catalyst is the same as that of Example 3.

[0271] Polymerization evaluation method 5 is adopted, and the polymerization evaluation method is the same as that of Example 41.

[0272] Example 44:

[0273] The preparation method of the catalyst is the same as that of Example 4.

[0274] Polymerization evaluation method 5 is adopted, and the polymerization evaluation method is the same as that of Example 41.

[0275] Example 45:

[0276] The preparation method of the catalyst is the same as that of Example 5.

[0277] Polymerization evaluation method 5 is adopted, and the polymerization evaluation method is the same as that of Example 41.

[0278] Table 1. Summary of catalyst olefin polymerization and evaluation results of its polymerization products

[0279]

[0280]

[0281] As can be seen from Examples 1-16, the catalyst prepared by the catalyst preparation method disclosed in this article has a relatively small average particle size, which is 3-6μm, and the particle size can be adjusted by adjusting the types and addition amounts of organic alcohols, silicon-containing compounds, and titanium-containing halides. The catalysts all show excellent catalytic activity for ethylene polymerization, and the catalytic activity can reach 4×10 4gPE / gCat. As can be seen from Examples 16 - 25, as the catalyst concentration in the polymerization reactor decreases, the molecular weight of the polymer shows an increasing trend. As can be seen from Examples 26 - 45, as the catalyst concentration in the polymerization reactor decreases and the polymerization temperature decreases, the molecular weight of the polymer shows an obvious increasing trend, but the activity of the catalyst and the bulk density of the polymer decrease, and the attenuation of the activity is more obvious. When the molecular weight is about 10 million, its activity can still reach more than 2×10 4 gPE / gCat, which is very beneficial for the development of ultra-high molecular weight polyethylene with low ash content.

[0282] The above are only the preferred embodiments of the present invention and are not used to limit the scope of implementation of the present invention; any modification or equivalent replacement of the present invention without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A main agent of an alkoxymagnesium-supported polyethylene catalyst, characterized in that, It is composed of a magnesium alkoxide carrier loaded with a titanium halide and an aryl ester compound.

2. The main agent of the alkoxymagnesium-supported polyethylene catalyst according to claim 1, characterized in that, The chemical structural formula of the magnesium alkoxide carrier is Mg(OR1)(OR2), where R1 and R2 are both alkyl groups containing 2 to 10 carbon atoms; preferably, R1 and R2 are both ethyl groups.

3. The main agent of the alkoxymagnesium-supported polyethylene catalyst according to claim 1 or 2, characterized in that The alkoxymagnesium carrier is in the shape of spherical particles, with an average particle size of 20 to 1500 μm and a bulk density of 0.30 to 0.40 g / cm 3 ; preferably, the alkoxymagnesium carrier has an average particle size of 200 to 700 μm and a bulk density of 0.32 to 0.38 g / cm 3 .

4. The main agent of the alkoxymagnesium-supported polyethylene catalyst according to claim 1, characterized in that, The aryl ester compound is at least one of dibutyl phthalate, diisobutyl phthalate, 1,3-dipentyl phthalate, methyl phenylacetate, ethyl benzoate, 1,3-butanediol dimethylbenzoate, 2,3-dimethyl-1,3-butanediol dibenzoate, phenethyl acrylate, phenyl methacrylate, 2-phenylethyl acrylate, 2,4-pentanediol dibenzoate, 2-methyl-3,5-heptanediol dibenzoate, 2,4-pentanediol dibenzoate, 4-ethyl-3,5-heptanediol dibenzoate; based on per mole of the magnesium alkoxide carrier, the dosage of the aryl ester compound is 0.1 - 100 moles, preferably 0.3 - 30 moles.

5. The main agent of the alkoxymagnesium-supported polyethylene catalyst according to claim 1, characterized in that, The titanium halide is selected from at least one of the general formula (R1O)aTi(OR2)b(OR3)cXd, where a, b, and c are integers between 0 and 4, d is an integer between 1 and 4, and a + b + c + d = 4, R1, R2, and R3 are hydrogen and / or alkyl groups, and X is at least one of chlorine and bromine; preferably, the titanium halide is selected from at least one of titanium tetrachloride, titanium tetrabromide, chloro-triethoxy titanium, dichloro-diethoxy titanium, trichloro-ethoxy titanium, triisopropoxy titanium chloride; based on per mole of the magnesium alkoxide carrier, the dosage of the titanium halide is 0.1 - 40 moles, preferably 1 - 20 moles.

6. A method for preparing the main agent of an alkoxymagnesium-supported polyethylene catalyst according to any one of claims 1 to 5, characterized in that, It includes the following steps: Under the protection of an inert gas, disperse the magnesium alkoxide carrier in an inert hydrocarbon organic solvent, then add an organic alcohol, stir and heat up to 50 - 100 °C to obtain a magnesium alkoxide carrier dispersion. Add the aryl ester compound to the magnesium alkoxide carrier dispersion, heat to 60 - 150 °C, stir and react for 1 - 4 hours, then cool to room temperature to obtain a mixed solution. Add the mixed solution to the titanium halide preheated to 60 - 80 °C, react for 0.5 - 2 hours to obtain a suspension. Cool the suspension to 0 - 40 °C, add a silicon-containing compound, stir and react for 0.5 - 4 hours to form a catalyst intermediate. Perform ultrasonic treatment on the catalyst intermediate. Heat the ultrasonic-treated catalyst intermediate to 40 - 80 °C, add an ether compound, stir and react for 0.5 - 4 hours, and after washing with an organic solvent, obtain the main catalyst.

7. The preparation method according to claim 6, wherein The inert hydrocarbon organic solvent is at least one of aliphatic hydrocarbons, cycloalkanes, and aromatic hydrocarbons; preferably, the inert hydrocarbon organic solvent is decane or toluene; based on per mole of the magnesium alkoxide carrier, the dosage of the inert hydrocarbon organic solvent is 4 - 40 moles.

8. The preparation method according to claim 6, characterized in that, The organic alcohol is at least one of straight-chain alcohols or isomeric alcohols having 1 to 20 carbon atoms; preferably, the organic alcohol is isooctyl alcohol or ethylene glycol; based on per mole of the magnesium alkoxide carrier, the amount of the organic alcohol used is 0.02 to 0.2 moles, preferably 0.05 to 0.1 moles.

9. The preparation method according to claim 6, characterized in that, The silicon-containing compound has the structure of R n SiCl 4-n wherein R is an alkyl group, hydrogen, or an oxygen-containing group, and 0 ≤ n ≤ 3; preferably, the silicon-containing compound is at least one of silicon tetrachloride, methyl dichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and dimethylchlorosilane; based on per mole of the magnesium alkoxide carrier, the amount of the silicon-containing compound used is 1-20 moles, preferably 1-5 moles.

10. The preparation method according to claim 6, characterized in that, The ether compound is at least one of lower aliphatic ethers or ether compounds containing two or more ether groups; preferably, the ether compound is methyl ether, ethyl ether, propyl ether, butyl ether, pentyl ether, 1,1-bis(methoxymethyl)cyclopentadiene, propylene oxide, tetrahydrofuran, methyl tert-butyl ether, 1,4-dioxane, 9,9-bis(methoxymethyl)fluorene; preferably, the ether compound is the cyclic ether 1,4-dioxane containing two ether groups; based on per mole of the magnesium alkoxide carrier, the amount of the ether compound used is 0.01 - 2 moles, preferably 0.1 - 1.5 moles.

11. The preparation method according to claim 6, wherein The time of the ultrasonic treatment is 0.1 - 1.5 hours, and the ultrasonic frequency is 20 KHz.

12. An alkoxymagnesium-supported polyethylene catalyst, characterized in that, It includes the main agent of the magnesium alkoxide carrier polyethylene catalyst described in any one of claims 1 - 5 and a catalyst activator, and the catalyst activator is an organoaluminum compound.

13. The alkoxymagnesium-supported polyethylene catalyst according to claim 12, wherein The organoaluminum compound is a chlorine-containing organoaluminum compound, and the chlorine-containing organoaluminum compound is dialkylaluminum monochloride with the chemical structural formula of R2AlCl or alkylaluminum sesquichloride with the chemical structural formula of R3Al2Cl3, where R is the same or different alkyl groups containing 1 - 5 carbon atoms.

14. The alkoxymagnesium-supported polyethylene catalyst according to claim 12, characterized in that, The organoaluminum compound is a chlorine-free organoaluminum compound, and the chlorine-free organoaluminum compound is trialkylaluminum AlR4 or AlR 42 H dialkylaluminum hydride, where R4 represents an alkyl group having 1 to 16 carbon atoms.

15. The alkoxymagnesium-supported polyethylene catalyst according to claim 12, wherein, Based on per mole of the magnesium alkoxide carrier, the amount of the catalyst activator used is 0.01 - 2 moles, preferably 0.02 - 0.2 moles.

16. A method for preparing a magnesium alkoxide-supported polyethylene catalyst according to any one of claims 12-15, characterized in that, It includes: Adding the catalyst activator to the main agent, and after activation at 20 - 40 °C, a catalyst slurry is prepared or a solid catalyst is obtained after drying.

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