Titanium catalyst component for ethylene polymerization, catalyst and preparation and application of titanium catalyst component

Abstract

The invention discloses a titanium catalyst component for ethylene polymerization, a catalyst and preparation and application of the titanium catalyst component. The preparation method of the catalyst component comprises the following steps: magnesium halide is dissolved in an organic solvent capable of dissolving magnesium halide, then an inorganic oxide carrier, a titanium-containing compound and tetrahydrofurfuryl alcohol or a derivative thereof are added in sequence, part of the organic solvent serves as other electron donors and forms a composite electron donor with tetrahydrofurfuryl alcohol or the derivative thereof, and the catalyst component is obtained. The raw materials are fully mixed to react to form suspension liquid, then spray drying forming is carried out, the spherical or sphere-like catalyst component is obtained, and the preparation method and synthesis steps of the catalyst component are simple. The obtained catalyst component has the characteristics of high activity and excellent copolymerization performance when catalyzing ethylene copolymerization or ethylene and alpha-olefin copolymerization under the action of the organic aluminum compound, and the obtained polyethylene powder has the advantages of high stacking density, relatively concentrated powder granularity and low fine powder content.

Description

Technical Field

[0001] The invention belongs to the field of catalysts, and in particular relates to a titanium-based catalyst component for ethylene polymerization, a catalyst, and a preparation method and application thereof. Background Art

[0002] Polyethylene is a plastic variety with the largest global production and wide application. With the development and progress of the polyethylene industry, the production of high value-added polymer resins has become the focus of scientific research. As the core of polyethylene technology, polyethylene catalysts occupy an irreplaceable position in the entire polyethylene development process. Among them, Ziegler-Natta catalysts (ZN catalysts) are the most important catalysts for the production of polyolefins. Research on catalysts mainly focuses on the polymerization activity of catalysts, the particle morphology and particle size distribution of catalysts, the hydrogen regulation performance of catalysts, and the copolymerization performance, and significant progress has been made. However, in order to better meet the needs of industrial production and obtain polyethylene resin products with better performance, the performance of catalysts needs to be further improved.

[0003] The grade of polyethylene resin products is determined by the melt index and density of the polymer powder. Therefore, the hydrogen adjustment performance and copolymerization performance of the catalyst are crucial to the production of new grades of polyethylene resin. When the traditional ZN catalyst catalyzes the copolymerization of ethylene and α-olefin, the content of inserted α-olefin in the obtained copolymer cannot meet people's needs. Therefore, improving the traditional ZN catalyst, improving the copolymerization performance of the catalyst, and improving the insertion efficiency of α-olefin to prepare linear low-density polyethylene (LLDPE) resin has certain theoretical significance and important use value.

[0004] Through the study of the copolymerization of ethylene and α-olefins catalyzed by ZN catalysts, people found that the polymerization conditions and the properties of the catalyst itself have an important influence on the copolymerization. For example, U.S. Patent US8546499B2 indicates that the type of alkyl aluminum can adjust the distribution of comonomers in the polymer chain. Professor Boisson reported in the journal AC Catalysis (ACS Catal. 2020, 10, 7216-7229) that the amount of co-catalyst triethylaluminum can not only regulate the kinetics of copolymerization, but also has a non-negligible effect on the distribution of comonomers in the polymer chain. It is worth noting that although the insertion of comonomers can be changed by changing the polymerization conditions, it is only regulated within a limited range. Improving the copolymerization performance by improving the traditional ZN catalyst is the most effective and direct way to produce new grades and high-performance products. As is known to all, in the synthesis process of ZN catalyst, the type of electron donor is crucial to the catalytic performance of the catalyst. For example, patent CN105384854A uses orthoesters as electron donors to synthesize catalysts to catalyze ethylene polymerization, which improves the bulk density of polymer powder; patents CN105111336A and CN105566524A respectively use organic cyclosiloxanes and gallic acid derivatives to improve the hydrogen adjustment performance of the catalyst. The copolymerization performance of the catalyst can also be improved by selecting a suitable electron donor. Patent CN101885793A uses a composite electron donor containing organic mercaptan to improve the copolymerization performance of the catalyst, but the catalyst synthesis step is relatively cumbersome, and mercaptan is a compound with a bad smell and has some toxicity. The steps of synthesizing the catalyst in patent CN101885795A are similar to those in CN101885793A. The use of a composite electron donor containing organic silicon amine can also improve the copolymerization performance of the catalyst, but the organic silicon amine compound will also have a certain smell and is more expensive. Patent CN104211844A discloses a gas phase fluidized bed LLDPE catalyst and its preparation method and application. This patent adopts a one-step method to prepare LLDPE catalyst. Although this catalyst system has high activity and hydrogen adjustment sensitivity, and the polyethylene product obtained has good morphology and high bulk density; however, the titanium loading process in the catalyst synthesis step requires a large amount of titanium tetrachloride, and also requires a large amount of toluene washing, and the catalyst particles are uneven. This not only increases the energy consumption and material consumption of the catalyst production process, but also pollutes the environment and brings harm to production personnel. Compared with patent CN104211844A, patent CN107759716A uses asymmetric silane compounds as electron donors to synthesize a catalyst suitable for gas phase polyethylene process. The catalyst has high activity, high copolymerization, high hydrogen adjustment sensitivity, and the polyethylene product obtained has good morphology, uniform particles, high bulk density, etc. However, the catalyst needs to add titanium tetrachloride twice, and still requires multiple washing operations, and the synthesis of the catalyst is still somewhat cumbersome. Summary of the invention

[0005] In order to overcome the problems existing in the prior art, the present invention provides a titanium catalyst component for ethylene polymerization and a preparation method thereof. The catalyst component uses tetrahydrofurfuryl alcohol or its derivatives and other electron donors to form a composite electron donor. When used for ethylene polymerization, especially for copolymerization of ethylene and α-olefins, the catalyst component exhibits excellent catalytic copolymerization performance. The Ziegler-Natta titanium catalyst for ethylene polymerization provided by the present invention is suitable for ethylene polymerization, especially for copolymerization of ethylene and α-olefins, to obtain linear low-density polyethylene resin.

[0006] One of the purposes of the present invention is to provide a titanium-based catalyst component for ethylene polymerization, comprising: an inorganic oxide carrier, and a reaction product of the following components supported on the inorganic oxide carrier: a magnesium halide, a titanium-containing compound, and a composite electron donor, wherein the composite electron donor comprises tetrahydrofurfuryl alcohol or its derivatives and other electron donors.

[0007] According to the present invention, the other electron donors are derived from part of the organic solvents in the synthesis process of the catalyst components. Specifically, the other electron donors are selected from at least one of alcohols, phenols, ketones, aldehydes, ethers, amines, pyridines, and titanates, preferably tetrahydrofuran.

[0008] According to the present invention, the structural formula of tetrahydrofurfuryl alcohol or its derivatives is as shown in formula (I):

[0009]

[0010] In formula (I), R1 is one of H and C1-C5 alkyl, R2, R3 and R4 are independently selected from one of H, C1-C15 straight-chain alkyl or branched-chain alkyl, C3-C15 cycloalkyl, C6-C15 aryl, hydroxyl, carbonyl, ester and carboxyl. Preferably, the tetrahydrofurfuryl alcohol or its derivative is selected from tetrahydrofurfuryl alcohol, 2-(hydroxymethyl)tetrahydrofuran-2,3,4-triol, 5-(hydroxymethyl)dihydrofuran-2(3H)-one, 3,4 - At least one of dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbaldehyde, lysonic acid-1,4-lactone, (5-methyltetrahydrofuran-2-yl)methanol, 5-(hydroxymethyl)tetrahydrofuran-3-ol, 1,2-dideoxy-D-ribofuranose, 2,5-dihydroxymethyltetrahydrofuran, 2-methyl-2-hydroxymethyltetrahydrofuran, 2-hydroxymethyl-5,5-dimethyltetrahydrofuran, and 2-(hydroxymethyl)tetrahydrofuran-3,4-diol, preferably tetrahydrofurfuryl alcohol.

[0011] According to the present invention, in the titanium-based catalyst component, the inorganic oxide carrier is selected from silicon oxide and / or aluminum oxide, preferably silicon dioxide; the particle size of the inorganic oxide carrier is 0.01 to 10 microns, preferably 0.01 to 5 microns, and more preferably 0.1 to 1 micron. Silicon oxide or aluminum oxide is an inert carrier. The use of an inert carrier in spray drying helps to control the shape and composition of the catalyst particles, and the generated catalyst particles have good shape, high strength, and are not easy to break. As a preferred embodiment, no matter which inorganic oxide carrier filler (filler) is selected, it should be dry, that is, without water molecules. The filler is dried by heating for a period of time at a temperature below the sintering or melting point of the filler material (however, some fillers, such as fumed silica, naturally have a low content of residual water molecules due to their specific manufacturing methods); generally, a temperature of at least 100°C is used for drying, and lower temperatures can be used when extended drying times are acceptable or when the filler has a low melting or sintering temperature; inorganic filler materials are generally dried at a temperature of 200 to 800°C; at the same time, the filler material can be treated with one or more Lewis acids (e.g., trialkylaluminum compounds or organosilanes) in an optional amount of 1 to 10 wt% to remove polar impurities including water or hydroxyl groups in the inert carrier.

[0012] According to the present invention, in the titanium-based catalyst component,

[0013] The magnesium halide is selected from at least one of magnesium fluoride, magnesium chloride, magnesium bromide and magnesium iodide, preferably magnesium chloride;

[0014] The titanium-containing compound is selected from at least one of a tetravalent titanium compound and a trivalent titanium compound. Preferably, the general formula of the tetravalent titanium compound is Ti(OR): k Cl (4-k) , where R is an alkyl group, 0≤k≤4; the trivalent titanium compound is obtained by reducing a tetravalent titanium compound. Wherein, the tetravalent titanium compound is selected from at least one of titanium tetrachloride, trichloromethoxytitanium, trichloroethoxytitanium, trichloro-n-butoxytitanium, dichlorodimethoxytitanium, dichlorodiethoxytitanium, dichloro-n-butoxytitanium, monochlorotrimethoxytitanium, monochlorotriethoxytitanium, monochlorotri-n-butoxytitanium, tetramethoxytitanium, tetraethoxytitanium, tetra-n-butoxytitanium, tetraisobutoxytitanium, and tetra(2-ethylhexyl)titanium, preferably titanium tetrachloride. The trivalent titanium compound is a trivalent titanium compound obtained by reducing the above-mentioned tetravalent titanium compound with metallic aluminum or with metallic magnesium, and most preferably, the product TiCl3·1 / 3AlCl3 of the reduction of titanium tetrachloride with metallic aluminum and / or the product TiCl3·1 / 2MgCl2 of the reduction of titanium tetrachloride with metallic magnesium. These titanium compounds can be used alone or in combination of two or more. These compounds can also be used after being diluted with the above-mentioned organic solvent for dissolving magnesium halide.

[0015] According to the present invention, in the titanium catalyst component, based on the total weight of the titanium catalyst component as 100wt%, the content of titanium element in the titanium catalyst component is 0.1-5.6wt%, the content of magnesium element is 2-11wt%, the content of composite electron donor is 10-40wt%, and the content of inorganic oxide carrier is 1-70wt%; preferably, based on the total weight of the titanium catalyst component as 100wt%, the content of titanium element in the titanium catalyst component is 1-3.5wt%, the content of magnesium element is 5.5-9wt%, the content of composite electron donor is 15-35wt%, and the content of inorganic oxide carrier is 20-50wt%. In the composite electron donor, the molar ratio of tetrahydrofurfuryl alcohol or its derivatives to other electron donors is 1:20-10:1, preferably 1:10-1:1.

[0016] The second object of the present invention is to provide a method for preparing the above-mentioned titanium-based catalyst component for ethylene polymerization, comprising: dissolving a magnesium halide in an organic solvent, then sequentially adding an inorganic oxide carrier, a titanium-containing compound, tetrahydrofurfuryl alcohol or a derivative thereof, stirring and mixing to obtain a suspension, and spray drying to obtain the catalyst component.

[0017] According to the present invention, during the preparation of the titanium-based catalyst component, part of the organic solvent is used as another electron donor to form a composite electron donor with tetrahydrofurfuryl alcohol or its derivatives.

[0018] According to the present invention, in the method for preparing the titanium-based catalyst component:

[0019] The mass ratio of the organic solvent to the magnesium halide is greater than 5:1, preferably (10-50):1;

[0020] The molar ratio of tetrahydrofurfuryl alcohol or its derivative to magnesium halide is (0.01-1):1, preferably (0.05-0.4):1;

[0021] The molar ratio of the titanium-containing compound to the magnesium halide is (0.01-1):1, preferably (0.1-0.5):1;

[0022] The molar ratio of the inorganic oxide support to the magnesium halide is (0.5-10):1, preferably (1-5):1.

[0023] According to the present invention, in the method for preparing the titanium-based catalyst component:

[0024] The organic solvent is selected from organic solvents capable of dissolving the magnesium halide, preferably at least one selected from alcohol, phenol, ketone, aldehyde, ether, amine, pyridine, and titanate, more preferably tetrahydrofuran;

[0025] The stirring and mixing is carried out under a protective gas atmosphere, for example, stirring and mixing under nitrogen protection;

[0026] The stirring and mixing temperature is 0 to 90°C, preferably 50 to 70°C;

[0027] The spray drying conditions are: an inlet temperature of 100-240°C, preferably 120-200°C; and / or an outlet temperature of 60-130°C, preferably 80-115°C.

[0028] According to an embodiment of the present invention, the preparation method of the titanium catalyst component for ethylene polymerization is as follows: under nitrogen inert atmosphere conditions, magnesium halide and an organic solvent that can dissolve magnesium halide are added in sequence, dissolved in a temperature range of 0 to 90°C for more than 0.1 hour, then an inorganic oxide carrier is added, stirred in a temperature range of 0 to 90°C for more than 0.5 hour, followed by adding a titanium-containing compound, reacting in a temperature range of 0 to 90°C for more than 0.1 hour, and finally adding an electron donor tetrahydrofurfuryl alcohol or a derivative thereof, reacting in a temperature range of 0 to 90°C for 0.1 to 96 hours to obtain a suspension. The suspension is then spray-dried to obtain a spherical or quasi-spherical catalyst component. The stirring temperature for preparing the catalyst suspension mother liquor is in a temperature range of 0 to 90°C, preferably 50 to 70°C.

[0029] The spray drying method is an effective method for preparing a high-efficiency ZN catalyst suitable for ethylene polymerization. The method can prepare the various components of the catalyst into a suspension, and then obtain the catalyst through a spraying step, which greatly simplifies the synthesis process of the catalyst. The present invention selects a new type of tetrahydrofurfuryl alcohol or its derivative electron donor, and uses the spray drying method to prepare a catalyst suitable for ethylene polymerization. The catalyst not only has good spherical particles, but also has high polymerization activity and excellent copolymerization performance, and has the potential to produce high value-added polyethylene on existing equipment.

[0030] The third object of the present invention is to provide an application of the titanium-based catalyst component for ethylene polymerization or the titanium-based catalyst component for ethylene polymerization obtained by the above-mentioned preparation method in a catalyst for ethylene polymerization.

[0031] A fourth object of the present invention is to provide a catalyst for ethylene polymerization, comprising:

[0032] (A) the titanium-based catalyst component for ethylene polymerization;

[0033] (B) Organic aluminum compounds.

[0034] According to the present invention, in the catalyst for ethylene polymerization, the titanium-based catalyst component catalyzes the ethylene polymerization reaction under the action of an organic aluminum compound. The general formula of the organic aluminum compound is AlR bX 3-b , wherein R is H, a C1-C20 alkyl group; X is a halogen, preferably chlorine or bromine; 0<b≤3, preferably, 1<b≤3; more preferably, the organoaluminum compound is selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, and diethylaluminum monochloride; the molar ratio of the aluminum element in the organoaluminum compound to the titanium element in the titanium-based catalyst component is (5-1000):1, preferably (10-200):1.

[0035] The fifth object of the present invention is to provide an application of the above catalyst for ethylene polymerization in ethylene homopolymerization or copolymerization of ethylene with other α-olefins. The other α-olefins are α-olefins containing C1 to C12 side groups, preferably, the other α-olefins are selected from at least one of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene; the temperature of the homopolymerization or copolymerization is 20 to 120°C, preferably 65 to 90°C.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] The invention adopts an organic solvent to dissolve magnesium halide, and adds a certain proportion of inorganic oxide carrier filler, titanium compound and electron donor tetrahydrofurfuryl alcohol or its derivative to form a suspension, and the obtained suspension is spray-dried to obtain a spherical solid catalyst. The solid catalyst has uniform particles and few microparticles; it is used for ethylene polymerization and copolymerization, has high catalytic activity, catalyzes the copolymerization of ethylene and alpha-olefin to obtain a low-density polymer, and the obtained polymer powder has high bulk density and low fine powder content.

[0038] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0040] The test instruments and test conditions used in the examples are as follows:

[0041] 1. Catalytic activity: expressed as the weight of resin obtained per gram of catalyst in two hours;

[0042] 2. Polymer melt index (MI): determined according to ASTM D1238-99, load 2.16 kg, 190°C;

[0043] 3. Polymer apparent bulk density (BD): tested in accordance with ASTM D1895-69.

[0044] 4. The basis of sieving analysis value: refer to ASTM D-1921 standard.

[0045] 5. Catalyst particle size: measured by MASTERSIZER2000 particle size analyzer, termed D 10 , D 50 , D 90 It means that the standard logarithmic particle size distribution has a special percentage distribution, such as the catalyst particle size with D 50 The median particle size is 24 μm; D 10 7μm means that 10% of the particles have a diameter less than 7μm. 90 45 μm means that 90% of the particles are smaller than 45 μm.

[0046] 6. Titanium and magnesium content: measured by Spectrumlab752s UV-visible spectrophotometer;

[0047] 7. The content of tetrahydrofuran and electron donor in the catalyst component was determined by liquid nuclear magnetic resonance. 1 HNMR and calculations.

[0048] 8. Polyethylene resin density: refer to ASTMD1505-2010 standard.

[0049] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0050] Example 1

[0051] (1) Preparation of solid titanium catalyst component

[0052] (1.1) Into a 250 ml four-necked flask equipped with a temperature controller, a stirrer, a reflux condenser, and nitrogen purging and protection, 4.0 g of MgCl2 and 100 ml of dehydrated tetrahydrofuran solvent were added in sequence, and stirred and dissolved at 65°C for 4 hours. Then, 5.7 g of fumed silica gel (Cabot Corporation TS-610, particle size 0.1-1 micron) was added and stirred for 1.5 hours to fully disperse the silica gel in the mother liquor. Then, 0.92 ml of titanium tetrachloride was added and reacted for 1.5 hours. Finally, 0.82 ml of tetrahydrofurfuryl alcohol was added and reacted for 2 hours to obtain a slurry suspension for spraying, which was set aside. The nitrogen atmosphere should be maintained throughout the whole process.

[0053] (1.2) In a closed-loop circulating airflow spray dryer (such as BüCHIMiniSprayDryer B-290 / B-295), the suspension obtained in step (1.1) is kept at a constant temperature of 43°C, and introduced into a two-fluid nozzle through a pipe using a peristaltic pump, and nitrogen with a carrier gas inlet temperature of 140°C is introduced into the spray dryer. The slurry suspension feed rate and the spray gas (N2) flow rate at room temperature are adjusted to 26 ml / min and 350 L / h, respectively, and the carrier gas (N2) flow rate is adjusted to make the outlet temperature 95°C. The powder is collected at the lower outlet of the cyclone separator to obtain a spherical solid titanium catalyst component. The catalyst particle composition is shown in Table 1.

[0054] (2) Ethylene slurry polymerization

[0055] 1L of hexane was added to a 2L polymerization reactor that was purged with nitrogen first and then hydrogen, and 1mL of 1M triethylaluminum hexane solution, 30mL of 1-hexene and 15mg of the solid titanium catalyst component obtained in step (1.2) were added at the same time, the temperature was raised to 85°C, hydrogen was added to 0.28MPa, and after the hydrogenation was completed, ethylene was added to 1.03MPa, and the reaction was carried out at a constant temperature and pressure of 85°C and 1.03MPa for 2 hours, then the reaction was stopped, and the temperature was lowered and the material was discharged. The polymerization results are shown in Table 2.

[0056] Example 2

[0057] The preparation process in Example 1 was followed, except that 0.41 mL of tetrahydrofurfuryl alcohol was added at the end of step (1.1) and the mixture was reacted for 2 hours.

[0058] Example 3

[0059] The preparation process is the same as in Example 1, except that 2.0 g of TiCl3·1 / 2MgCl2 is added in step (1.1). TiCl3·1 / 2MgCl2 is a trivalent titanium chloride compound formed by reducing the precursor titanium tetrachloride with metallic magnesium.

[0060] Example 4

[0061] The preparation process in Example 1 was followed, except that 3.5 g MgCl2 and 0.7 mL TiCl4 were added in step (1.1).

[0062] Example 5

[0063] The preparation process in Example 1 was followed, except that 6.0 g MgCl2 and 1.15 mL TiCl4 were added in step (1.1).

[0064] Comparative Example 1

[0065] Compared with Example 1, the only difference is that "finally, 0.82 mL of tetrahydrofurfuryl alcohol is added and reacted for 2 hours" in (1.1) is removed. That is, titanium tetrachloride is added and reacted for 1.5 hours to obtain a slurry suspension, which is sprayed to obtain spherical and quasi-spherical catalysts.

[0066] Table 1. Catalyst components and particle size

[0067]

[0068] Table 2. Data of ethylene and 1-hexene copolymerization catalyzed by catalysts

[0069]

[0070] From the catalytic results in Table 2, it can be seen that the catalyst of the present invention has high activity in catalyzing the copolymerization of ethylene and 1-hexene, and the obtained polyethylene powder has a high bulk density, a relatively concentrated particle size distribution, and less subdivision. And from the density of the obtained powder, it can be seen that the catalyst of the present invention has more excellent copolymerization performance, which is conducive to the production of a polyethylene resin with lower density and high performance.

[0071] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A titanium catalyst component for ethylene polymerization, comprising: An inorganic oxide carrier and a reaction product of the following components supported on the inorganic oxide carrier: magnesium halide, a titanium-containing compound, and a composite electron donor, wherein the composite electron donor comprises tetrahydrofurfuryl alcohol or its derivatives and other electron donors.

2. The titanium-based catalyst component according to claim 1, characterized in that The other electron donor is selected from at least one of alcohol, phenol, ketone, aldehyde, ether, amine, pyridine and titanate, preferably tetrahydrofuran; and / or, The inorganic oxide carrier is selected from silicon oxide and / or aluminum oxide, preferably silicon dioxide; and / or, The particle size of the inorganic oxide carrier is 0.01 to 10 microns, preferably 0.01 to 5 microns; and / or, The magnesium halide is selected from at least one of magnesium fluoride, magnesium chloride, magnesium bromide and magnesium iodide, preferably magnesium chloride; and / or, The titanium-containing compound is selected from at least one of a tetravalent titanium compound and a trivalent titanium compound. Preferably, the general formula of the tetravalent titanium compound is Ti(OR): k Cl (4-k) , wherein R is an alkyl group, 0≤k≤4; and / or, the trivalent titanium compound is obtained by reducing a tetravalent titanium compound.

3. The titanium-based catalyst component according to claim 2, characterized in that The structural formula of the tetrahydrofurfuryl alcohol or its derivatives is shown in formula (I): In formula (I), R1 is one of H and C1-C5 alkyl, R2, R3 and R4 are independently selected from one of H, C1-C15 straight-chain alkyl or branched alkyl, C3-C15 cycloalkyl, C6-C15 aryl, hydroxyl, carbonyl, ester and carboxyl; preferably, the tetrahydrofurfuryl alcohol or its derivative is selected from tetrahydrofurfuryl alcohol, 2-(hydroxymethyl)tetrahydrofuran-2,3,4-triol, 5-(hydroxymethyl)dihydrofuran-2(3H)-one, 3,4-dihydrofuran-2(3H)-one, At least one of hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-carbaldehyde, lysonic acid-1,4-lactone, (5-methyltetrahydrofuran-2-yl)methanol, 5-(hydroxymethyl)tetrahydrofuran-3-ol, 1,2-dideoxy-D-ribofuranose, 2,5-dihydroxymethyltetrahydrofuran, 2-methyl-2-hydroxymethyltetrahydrofuran, 2-hydroxymethyl-5,5-dimethyltetrahydrofuran, 2-(hydroxymethyl)tetrahydrofuran-3,4-diol, preferably tetrahydrofurfuryl alcohol; and / or, The tetravalent titanium compound is selected from at least one of titanium tetrachloride, trichloromethoxytitanium, trichloroethoxytitanium, trichloro-n-butoxytitanium, dimethoxytitanium dichloride, diethoxytitanium dichloride, di-n-butoxytitanium dichloride, trimethoxytitanium monochloride, triethoxytitanium monochloride, tri-n-butoxytitanium monochloride, tetramethoxytitanium, tetraethoxytitanium, tetra-n-butoxytitanium, tetraisobutoxytitanium, and tetra(2-ethylhexyloxy)titanium, preferably titanium tetrachloride.

4. The titanium-based catalyst component according to claim 1, characterized in that Based on the total weight of the titanium-based catalyst component being 100 wt%, the content of the titanium element in the titanium-based catalyst component is 0.1 to 5.6 wt%, the content of the magnesium element is 2 to 11 wt%, the content of the composite electron donor is 10 to 40 wt%, and the content of the inorganic oxide carrier is 1 to 70 wt%; Preferably, based on the total weight of the titanium-based catalyst component as 100wt%, the content of titanium element in the titanium-based catalyst component is 1-3.5wt%, the content of magnesium element is 5.5-9wt%, the content of composite electron donor is 15-35wt%, and the content of inorganic oxide carrier is 20-50wt%.

5. A method for preparing the titanium-based catalyst component for ethylene polymerization according to any one of claims 1 to 4, comprising: The magnesium halide is dissolved in an organic solvent, and then an inorganic oxide carrier, a titanium-containing compound, tetrahydrofurfuryl alcohol or a derivative thereof are added in sequence, stirred and mixed uniformly to obtain a suspension, and spray-dried to obtain the catalyst component.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the organic solvent to the magnesium halide is greater than 5:1, preferably (10-50):1; and / or, The molar ratio of tetrahydrofurfuryl alcohol or its derivative to magnesium halide is (0.01-1):1, preferably (0.05-0.4):1; and / or, The molar ratio of the titanium-containing compound to the magnesium halide is (0.01-1):1, preferably (0.1-0.5):1; and / or, The molar ratio of the inorganic oxide support to the magnesium halide is (0.5-10):1, preferably (1-5):

1.

7. The preparation method according to claim 5, characterized in that: The organic solvent is selected from at least one of alcohol, phenol, ketone, aldehyde, ether, amine, pyridine and titanate, preferably tetrahydrofuran; and / or, The stirring and mixing is carried out under a protective gas atmosphere; and / or, The stirring and mixing temperature is 0 to 90° C., preferably 50 to 70° C.; and / or, The spray drying conditions are: an inlet temperature of 100-240°C, preferably 120-200°C; and / or an outlet temperature of 60-130°C, preferably 80-115°C.

8. Use of the titanium-based catalyst component for ethylene polymerization as claimed in any one of claims 1 to 4 or the titanium-based catalyst component for ethylene polymerization obtained by the preparation method as claimed in any one of claims 5 to 7 in a catalyst for ethylene polymerization.

9. A catalyst for ethylene polymerization, comprising: (A) the titanium-based catalyst component for ethylene polymerization according to any one of claims 1 to 4 or the titanium-based catalyst component for ethylene polymerization obtained by the preparation method according to any one of claims 5 to 7; (B) Organic aluminum compounds.

10. The catalyst according to claim 9, characterized in that The general formula of the organoaluminum compound is AlR b X 3-b , wherein R is H, a C1-C20 alkyl group; X is a halogen, preferably chlorine or bromine; 0<b≤3, preferably, 1<b≤3; more preferably, the organoaluminum compound is selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, and diethylaluminum monochloride; and / or, The molar ratio of the aluminum element in the organic aluminum compound to the titanium element in the titanium-based catalyst component is (5-1000):1, preferably (10-200):

1.

11. Use of the catalyst for ethylene polymerization according to claim 9 or 10 in ethylene homopolymerization or copolymerization of ethylene and other α-olefins.

12. The use according to claim 11, characterized in that: The other α-olefin is an α-olefin containing C1 to C12 side groups, preferably, the other α-olefin is selected from at least one of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene; and / or, The temperature of the homopolymerization or copolymerization reaction is 20 to 120°C, preferably 65 to 90°C.

Images