A ziegler-natta catalyst for olefin polymerization and a method for preparing the same

Abstract

The application discloses a Ziegler-Natta catalyst for olefin polymerization, and adopts a heteroatom-containing bicyclic succinate compound shown as a general formula (I) as an internal electron donor. Because of the unique coordination mode and special space electronic structure of the compound, the catalyst obtained after loading has high catalytic activity when catalyzing propylene polymerization, the product polypropylene can reach high stereoregularity, and the molecular weight distribution is wide, so that various grades of polymer products can be developed. The application further discloses a preparation method of the supported catalyst.

Description

Technical Field

[0001] This invention belongs to the field of preparation of supported Ziegler-Natta catalysts for olefin polymerization, specifically relating to a catalyst for propylene (co)polymerization and its preparation method. Background Technology

[0002] Supported Ziegler-Natta catalysts contain basic components such as magnesium, titanium, halogens, and internal and external electron donors. They are particularly suitable for the polymerization of α-olefins with three or more carbon atoms, yielding olefin polymers with high yields and stereoregularity. Studies have shown that electron donors are an essential component of supported Ziegler-Natta catalysts, and polyolefin catalysts are constantly being updated and improved with the development of electron donor compounds.

[0003] Currently, diaromatic carboxylic acid esters, such as di-n-butyl phthalate or diisobutyl phthalate, are commonly used in industry (PMTrivedi, et al. J. Polym. Res., 2021, 28, Article number: 45). However, phthalates are typical plasticizers, and long-term use can be harmful to human health. Therefore, researchers have developed many non-phthalate electron donors for supported Ziegler-Natta catalysts. Typical examples are 1,3-diether compounds, such as 9,9-di(methoxymethyl)fluorene, recently disclosed in CN1090194C, CN00103538, and CN1137155C. Ziegler-Natta catalysts supported on these compounds exhibit high activity and isotacticity in propylene polymerization. Researchers have recently attempted to use other compounds as electron donors in olefin polymerization catalysts, such as the 1,8-naphthodiol esters (WO2011084691A2 and US20110213106A1) reported by Chang et al. of BASF and the 1,2-benzenediol esters (US20190338054A1 and CN102325808A) disclosed by Dow. These electron donor-supported catalysts have high activity and isotacticity. However, whether they are 1,3-diethers or diol esters, they are difficult to synthesize, and the polymers obtained by olefin polymerization catalyzed by the supported catalysts have a narrow molecular weight distribution, making the materials difficult to process.

[0004] To address this issue, Basell developed catalysts using succinates (butanedioates) as electron donors, which not only possess high stereotactic properties and catalytic activity but also exhibit a wide relative molecular mass distribution of polyolefins (CN1313869). Examples include 2,3-diisopropylsuccinate disclosed in patents such as WO2002030998, and polycyclic succinate electron donor compounds published by PetroChina (CN101831016A and CN101423571A). However, the synthesis of these compounds is complex and requires low temperatures (e.g., -85°C, CN201310071720), which significantly limits the synthesis and industrial application of succinate compounds. Summary of the Invention

[0005] The object of this invention is to provide a catalyst for the polymerization of CH2=CHR olefins, wherein R is hydrogen or a hydrocarbon group having 1-12 carbon atoms. Another object of this invention is to provide a method for preparing the catalyst described above.

[0006] Catalysts specifically include:

[0007] (a) Main catalyst: comprising, by weight percentage, 10%–25% magnesium, 1%–10% titanium, 40%–60% halogen and 1%–30% internal electron donor, characterized in that the internal electron donor compound is selected from at least one succinate of general formula (I):

[0008]

[0009] (b) Alkyl aluminum compounds;

[0010] (c) Optionally, an external electron donor component;

[0011] Wherein, group X is a heteroatom such as oxygen, sulfur, or nitrogen, and groups R1 and R2 may be the same or different from each other, and are C1 to C2. 20 The linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl groups may optionally contain heteroatoms; groups R3 to R8 may be the same or different from each other, and are hydrogen or C1-C6. 20 The linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups, optionally containing heteroatoms, and two or more groups from R3 to R8 can bond together to form one or more fused ring structures.

[0012] The molar ratio of titanium to aluminum to external electron donor compound is 1:5 to 1000:0 to 500 for each component in the catalyst.

[0013] Furthermore, in the above technical solution, in the above compound formula (I), X is preferably an oxygen atom.

[0014] Furthermore, in the above technical solution, in the above compound formula (I), R1 and R2 are preferably C1 to C2. 10 Alkyl, cycloalkyl, or arylalkyl groups, more preferably C1-C1. 10 Alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or neopentyl, with ethyl, isopropyl, n-butyl or isobutyl being particularly preferred.

[0015] Furthermore, in the above technical solution, in the above compound general formula (I), preferably at least one of the three groups R3 and R4; R5 and R6; R7 and R8 is hydrogen, more preferably both R3 and R4 are hydrogen.

[0016] Furthermore, in the above technical solutions, the general formula (I) of the above compounds includes, but is not limited to: dimethyl 7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate, diethyl 7-thiabicyclo[2.2.l]hept-2,3-dicarboxylate, di-n-butyl 7-methyl-7-amine-bicyclo[2.2.l]hept-2,3-dicarboxylate, diisopropyl 7-amine-bicyclo[2.2.l]hept-2,3-dicarboxylate, di-n-butyl 7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate, and 1-methyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate. - Diisobutyl dicarboxylate, 1-methyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate dineopentanol, 1,4-dimethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate dineopentanol, 5,6-dimethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate diisobutyl ester, 1,2,3,4-tetramethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate dineopentanol or 1,4,5,6-tetramethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate diisobutyl ester.

[0017] Furthermore, in the above technical solution, the precursor of the compound of general formula (I) can be obtained by esterification and Diels-Alder reaction, and finally by heterogeneous hydrogenation to obtain (I). For details on the synthesis of the precursor of compound of general formula (I), please refer to CN101824108A and CN101831016A. In the following synthetic route, the substituents R1, R2, R5-R7 and X in the structural formula are defined as R1, R2, R5-R7 and X in formula (I).

[0018]

[0019] Furthermore, in the above technical solution, the particle size distribution of magnesium in the catalytic component is 20–250 μm, with the general formula Mg(OR')mM. (2-m) The ·nROH is provided by magnesium halide alkoxides, where R' is C1 to C2.20 an alkyl group, an arylalkyl group or an aryl group; M is a halogen; m is an integer of 0 ≤ m ≤ 2; n is a decimal or an integer of 0 < n < 6; R is a C1-C 20 alkyl group or arylalkyl group.

[0020] Mg(OR')mM(2 - m)+nROH → Mg(OR′) m M (2-m) ·nROH

[0021] The magnesium halide in the magnesium halide alcoholate is selected from one of magnesium dichloride, magnesium dibromide, chloromethoxymagnesium or chloroethoxymagnesium; the alcohol in the magnesium halide alcoholate is selected from one of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol, preferably ethanol.

[0022] Furthermore, in the above technical solution, the magnesium halide alcoholate is synthesized according to the literature report (US4399054). Taking the synthesis of the ethanolate of magnesium chloride as an example, the specific synthesis method is as follows: At room temperature, 24 g of anhydrous MgCl2, 390 mL of vaseline oil, 50 mL of anhydrous ethanol, 10 mL of silicone oil and 2 mL of span are added to a high-pressure reactor. Under nitrogen protection, it is stirred and heated to 130 °C and reacted for 3 hours to completely dissolve the solid. Then, nitrogen is continuously filled into the reactor and maintained at a pressure of 1 MPa. The discharge valve is opened, and the mixture in the reactor is passed through a thin tube with a diameter of 1.2 mm and a length of 3.54 m, washed 5 times with hexane, and dried at room temperature to obtain a spherical carrier of the ethanolate of MgCl2.

[0023] The titanium in the catalytic component is provided by a compound with the general formula TiA n (OR) 4-n , where R is a hydrocarbon group with 1 to 20 carbon atoms; A is a halogen; n = 1 to 4. Specific compounds such as titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tetrabutoxy titanium, monochloro triethoxy titanium, dichloro diethoxy titanium or trichloro monoethoxy titanium are provided, preferably titanium tetrachloride.

[0024] The present invention provides a preparation method of the catalytic component a, including: ((1) adding spherical magnesium halide alcoholate particles to titanium halide liquid at -50 to 20 °C, reacting for 10 min to 5 h, and the molar ratio of magnesium to titanium is 1:5 to 1:100; (2) heating to 0 to 80 °C, adding an internal electron donor compound, and the molar ratio of magnesium to the internal electron donor compound is 2:1 to 20:1; (3) further heating to 100 to 150 °C and reacting for 1 to 6 h; (4) after filtration, adding the same titanium halide liquid as in step (1), reacting at 110 to 130 °C for 1 to 4 h, and then filtering, washing, and vacuum drying to obtain a supported catalyst.

[0025] The preferred preparation method is as follows: (1) Add spherical magnesium halide alkoxide particles to titanium halide liquid at -30 to 0℃ and react for 1 to 5 hours. The molar ratio of magnesium to titanium is 1:10 to 1:50. (2) Heat to 30 to 60℃ and add an internal electron donor compound. The molar ratio of magnesium to internal electron donor compound is 2:1 to 12:1. (3) Heat to 110 to 130℃ and react for 1 to 4 hours. (4) After filtration, add the same titanium halide liquid as in step (1) and react at 110 to 130℃ for 1 to 2 hours. After filtration, washing, and vacuum drying, the supported catalyst is obtained.

[0026] In addition to the main catalyst, there are also alkyl aluminum compounds and external electron donor components;

[0027] The molar ratio of titanium:aluminum:external electron donor compound is 1:5 to 1000:0 to 500.

[0028] Furthermore, in the above technical solution, the alkylaluminum compound is a trialkylaluminum compound, preferably one or a mixture of triethylaluminum, triisobutylaluminum, and tri-n-butylaluminum.

[0029] Furthermore, in the above technical solution, external electron donors can be selectively added as needed. For olefin polymers requiring high stereoregularity (e.g., isomorphism index greater than 99%), the addition of external electron donor compounds is recommended.

[0030] Furthermore, in the above technical solution, the external electron donor can be selected as R”'. n Si(OR””) 4-n Organosilicon compounds, where 0 ≤ n ≤ 3 integers; R”' and R”” are the same or different alkyl, cycloalkyl or aryl groups, optionally containing heteroatoms; R can also be a halogen or hydrogen atom.

[0031] Furthermore, in the above technical solution, the organosilicon compound includes: trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, cyclohexylmethyldimethoxysilane, methyltert-butyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, di-n-butyldimethoxysilane, dicyclopentyldimethoxysilane, or di(cyclobutylmethyl)dimethoxysilane, preferably diphenyldimethoxysilane.

[0032] Furthermore, in the above technical solution, the preferred molar ratio of each component in the catalyst is 1:25 to 100:25 to 300, based on the molar ratio between titanium, aluminum, and the external electron donor compound.

[0033] The catalyst described in this invention is used for olefin polymerization, particularly for the homopolymerization of propylene or the copolymerization of propylene with other olefins, and can produce polymers with very high isotropic indexes. Furthermore, its applicability to the production of polyethylene and copolymerization of ethylene with α-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, or 1-octene is not excluded.

[0034] Various methods available in the art can be used for propylene polymerization, which can be carried out in the liquid phase, gas phase, or a combination of liquid and gas phase polymerization stages. Polymerization is typically carried out at 0–150°C, preferably 40–90°C. The polymerization pressure is 0.01–10 MPa. Hydrogen or other compounds that can act as chain transfer agents can be used to control the molecular weight of the polymer.

[0035] This invention utilizes a special structure containing heteroatom-containing bicyclic succinate compound as an internal electron donor. Its unique electronic effect results in excellent overall catalyst performance. When used for propylene (co)polymerization, it can achieve satisfactory polymerization yields, and the polymer exhibits high stereoorientation. At the same time, the catalyst is also highly sensitive to hydrogen regulation, and the resulting polymer has a wide molecular weight distribution, which is beneficial for the development of different polymer grades. Detailed Implementation

[0036] The following examples are used to further illustrate the present invention, but not to limit the invention.

[0037] I. Synthesis of Succinate Compounds

[0038] The succinate described in this invention can be obtained by reaction with Diels-Alder and heterogeneous catalytic hydrogenation. Dibutyl phthalate (99%) and dibutyl succinate (99%) were purchased from TCI (Shanghai) Chemical Industry Development Co., Ltd.

[0039] Example 1 Synthesis of dinepentyl 1,4-dimethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylic acid dipentyl alcohol ester.

[0040] Add 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioic acid dineopentyl ester to a 150 mL flask, and stir and reflux overnight. Separate by column chromatography to obtain 39.5 g of colorless, clear liquid product, 1,4-dimethyl-7-oxabicyclo[2.2.l]hept-2,5-diene-2,3-dicarboxylic acid dineopentyl ester, with a yield of 90%. 1 1H NMR (TMS, CDCl3, 400MHz) analysis results: δ6.92 (s, 2H); δ4.07 (m, 4H); δ1.51 (s, 6H); δ1.06 (s, 18H).

[0041] 36.8 g of 1,4-dimethyl-7-oxabicyclo[2.2.l]hept-2,5-diene-2,3-dicarboxylic acid dineopentyl ester and 200 mg of commercial Pd / C catalyst were placed in a high-pressure reactor. The air in the reactor was replaced with hydrogen, and finally 1.0 MPa of hydrogen was introduced. The reaction was carried out at 50 °C for 2 hours to obtain 37.2 g of 1,4-dimethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylic acid dineopentyl ester, with a yield of 99%. 1 The H NMR results are shown in Table 1.

[0042] Example 2

[0043] Synthesis of dimethyl 7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate. The synthesis method was the same as in Example 1, except that 17.0 g of furan and 17.8 g of dimethyl butynedioate were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of dipentyl butynedioate dipentyl alcohol ester, with an overall yield of 88%. 1 The H NMR results are shown in Table 1.

[0044] Example 3

[0045] Synthesis of diethyl 7-thiabicyclo[2.2.l]hept-2,3-dicarboxylate. The synthesis method was the same as in Example 1, except that 21.0 g of thiophene and 21.3 g of diethyl butynedioate were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of dipentyl butynedioate dipentyl alcohol ester, with an overall yield of 91%. 1 The H NMR results are shown in Table 1.

[0046] Example 4

[0047] Synthesis of di-n-butyl 7-methyl-7-amine-bicyclo[2.2.l]hept-2,3-dicarboxylate. The synthesis method was the same as in Example 1, except that 20.3 g of N-methylpyrrole and 28.3 g of di-n-butyl butynedioate were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate, with an overall yield of 85%. 1 The H NMR results are shown in Table 1.

[0048] Example 5

[0049] Synthesis of diisopropyl 7-methyl-7-amine-bicyclo[2.2.l]hept-2,3-dicarboxylic acid. The synthesis method was the same as in Example 1, except that 20.3 g of N-methylpyrrole and 24.8 g of diisopropyl butynedioic acid were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of dipentyl butynedioic acid dipentyl alcohol ester, with an overall yield of 95%. 1 The H NMR results are shown in Table 1.

[0050] Example 6

[0051] Synthesis of di-n-butyl 7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate. The synthesis method was the same as in Example 1, except that 17.0 g of furan and 28.3 g of di-n-butyl butynedioate were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate, with an overall yield of 91%. 1 The H NMR results are shown in Table 1.

[0052] Example 7

[0053] Synthesis of 1-methyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylic acid diisobutyl ester. The synthesis method was the same as in Example 1, except that 20.5 g of 2-methylfuran and 28.3 g of butynedioic acid diisobutyl ester were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of butynedioic acid dineopentyl ester, with an overall yield of 90%. 1 The H NMR results are shown in Table 1.

[0054] Example 8

[0055] Synthesis of 1-methyl-7-oxabicyclo[2.2.l]hepta-2,3-dicarboxylic acid dineopentol ester. The synthesis method was the same as in Example 1, except that 20.5 g of 2-methylfuran and 31.8 g of butynedioic acid dineopentol ester were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of butynedioic acid dineopentol ester, with an overall yield of 90%. 1 The H NMR results are shown in Table 1.

[0056] Example 9

[0057] Synthesis of diisobutyl 5,6-dimethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate. The synthesis method was the same as in Example 1, except that 24.0 g of 2,5-dimethylfuran and 31.8 g of dipentyl butynedioate were replaced with 24.0 g of 3,4-dimethylfuran and 28.3 g of diisobutyl butynedioate, with an overall yield of 95%. 1 The H NMR results are shown in Table 1.

[0058] Example 10

[0059] Synthesis of diisobutyl 1,4,5,6-tetramethyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate. The synthesis method was the same as in Example 1, except that 31.0 g of 2,3,4,5-tetramethylfuran and 28.3 g of diisobutyl butynedioate were used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate, with an overall yield of 91%. 1 The H NMR results are shown in Table 1.

[0060] Table 1. Internal electron donors 1HNMR results

[0061]

[0062] II. Preparation of catalytic component a

[0063] TiCl4 was added to a dry, nitrogen-protected glass reactor and cooled to -20°C. Microspheres of magnesium chloride ethanolate (magnesium-to-ethanol ratio 2.9:1) were added with stirring, at a ratio of 1g:20mL. The reaction mixture was heated uniformly from -20°C to 0°C, then to 70°C. An internal electron donor was added to the reactor, and the reaction mixture was heated to 110°C and reacted for another 2 hours. After filtration, an equal amount of fresh TiCl4 was added, and the mixture was heated to 120°C and reacted for another 2 hours. After filtration, the filter cake was washed with hexane and dried under vacuum to obtain the catalyst component. The loading of the internal electron donor was determined using an Angent 8890A gas chromatograph; the titanium loading was determined using a spectrophotometer.

[0064] III. Propylene Polymerization

[0065] 0.2 mL of the external electron donor dicyclopentyldimethoxysilane, 8.0 mL of a 1 mol / L hexane solution of the co-catalyst triethylaluminum, and 0.01 mmol (calculated as titanium) of catalyst component a prepared in this invention were added sequentially to a 5 L autoclave. 2.5 L of liquid propylene and 0.2 MPa of hydrogen gas were introduced, and the mixture was stirred and mixed evenly at room temperature. The temperature was raised to 70 °C and stirred for 2 h. The polypropylene was removed from the autoclave, cooled to room temperature, and weighed after the propylene had completely evaporated. The activity of the catalyst was calculated, and the isotacticity, bulk density, melt index, particle size distribution, and molecular weight distribution of the polypropylene were determined.

[0066] Examples 11-20 involved propylene polymerization using the Ziegler-Natta catalyst synthesized with electron donors from Examples 1-10, followed by the polymerization steps described above. The polymerization results are shown in Table 2.

[0067] Table 2. Aggregation Results

[0068]

[0069] The results above show that the synthesized catalyst with succinate as the internal electron donor has significantly better activity and isotacticity than commercially available catalysts supported on di-n-butyl phthalate and di-n-butyl succinate.

Claims

1. A Ziegler-Natta catalyst for olefin polymerization, specifically comprising: (a) Main catalyst: comprising, by weight percentage, 10%–25% magnesium, 1%–10% titanium, 40%–60% halogen and 1%–30% internal electron donor, characterized in that the internal electron donor compound is selected from at least one succinate of general formula (I): (I) (b) Alkyl aluminum compounds; (c) Optionally, an external electron donor component; Wherein, group X is an oxygen, sulfur, or nitrogen heteroatom, and groups R1 and R2 may be the same or different from each other, selected from C1 to C2. 20 The linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl groups, optionally containing heteroatoms; groups R3, R4, R5, R6, R7, and R8 may be the same or different from each other, and are selected from hydrogen or C1~C1. 20 The linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups, optionally containing heteroatoms, and two or more groups in R3, R4, R5, R6, R7, R8 can bond to each other to form one or more fused ring structures. Based on the molar ratio of titanium:aluminum:external electron donor compound, the molar ratio of each component in the catalyst is 1:5~1000:0~500.

2. The catalyst according to claim 1, characterized in that... In the general formula (I) of the compound, R1 and R2 are ethyl, isopropyl, n-butyl, isobutyl or neopentyl.

3. The catalyst according to claim 1, characterized in that... In the general formula (I) of the compound, at least one of the three groups R3 and R4; R5 and R6; R7 and R8 is a hydrogen group.

4. The catalyst according to claim 1, characterized in that... The internal electron-donating compounds of general formula (I) are 7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate, 7-thiabicyclo[2.2.l]hept-2,3-dicarboxylate diethyl ester, 7-methyl-7-amine-bicyclo[2.2.l]hept-2,3-dicarboxylate di-n-butyl ester, 7-amine-bicyclo[2.2.l]hept-2,3-dicarboxylate diisopropyl ester, 7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate di-n-butyl ester, 1-methyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate diisobutyl ester, 1-methyl-7-oxabicyclo[2.2.l]hept-2,3-dicarboxylate dineopentanol ester, and 1,4-dimethyl-7-oxabicyclo[2.2.l]. [l]hepta-2,3-dicarboxylic acid dineopentyl ester, 5,6-dimethyl-7-oxabicyclo[2.2.l]hepta-2,3-dicarboxylic acid diisobutyl ester, 1,2,3,4-tetramethyl-7-oxabicyclo[2.2.l]hepta-2,3-dicarboxylic acid dineopentyl ester or 1,4,5,6-tetramethyl-7-oxabicyclo[2.2.l]hepta-2,3-dicarboxylic acid diisobutyl ester.

5. The catalyst according to claim 1, characterized in that... The magnesium in the main catalyst component has a particle size distribution of 20–250 µm, with the general formula Mg(OR')mM. (2-m) • Provided by magnesium halide alkoxides of nROH, where R' is C1~C2. 20 alkyl, arylalkyl, or aryl; M is a halogen; m is an integer where 0 ≤ m ≤ 2; n is a decimal or an integer where 0 < n < 6; R is an alkyl or aralkyl group of C1~C 20 alkyl or aralkyl; The titanium in the catalytic component is of the general formula TiA n (OR'') 4-n The compound is provided, where R'' is a hydrocarbon group with 1 to 20 carbon atoms; A is a halogen; n = 1 to 4.

6. The catalyst according to claim 5, characterized in that... In the magnesium halide alkoxides that provide magnesium, the magnesium halide is one of magnesium dichloride, magnesium dibromide, magnesium chloromethoxymethyl ... The titanium in the main catalyst component is provided by titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium monochlorotriethoxy, titanium dichlorodiethoxy, or titanium trichloromonethoxy.

7. The catalyst according to any one of claims 1-6, characterized in that... The specific process for preparing the main catalyst includes: (1) adding spherical magnesium halide alkoxide particles to titanium halide liquid at -50~20℃ and reacting for 10min to 5h, with the molar ratio of magnesium to titanium being 1:5~1:100; (2) heating to 0~80℃ and adding an internal electron donor compound, with the molar ratio of magnesium to internal electron donor compound being 2:1~20:1; (3) heating to 100~150℃ and reacting for 1~6h; (4) filtering and then adding the same titanium halide liquid as in step (1), reacting at 110~130℃ for 1~4h, and then filtering, washing, and vacuum drying to obtain the supported catalyst.

8. The catalyst according to claim 7, characterized in that... The preparation process of the main catalyst is as follows: (1) Add spherical magnesium halide alkoxide particles to titanium halide liquid at -30~0℃ and react for 1 to 5 hours. The molar ratio of magnesium to titanium is 1:10~1:

50. (2) Heat to 30~60℃ and add internal electron donor compound. The molar ratio of magnesium to internal electron donor compound is 2:1~12:

1. (3) Heat to 110~130℃ and react for 1~4 hours. (4) After filtration, add titanium halide liquid in the same way as in step (1) and react at 110~130℃ for 1~2 hours. After filtration, washing, and vacuum drying, the supported catalyst is obtained.

9. The catalyst according to claim 1, characterized in that... Alkyl aluminum compounds are trialkyl aluminum compounds; External electron donors are those with the general formula R''' n Si(OR'''') 4-n Organosilicon compounds, where 0 ≤ n ≤ 3 integers; R''' and R'''' are the same or different alkyl, cycloalkyl or aryl groups.

10. The catalyst according to claim 9, characterized in that... The trialkylaluminum compound is selected from one or more mixtures of triethylaluminum, triisobutylaluminum, and tri-n-butylaluminum.

11. The catalyst according to claim 9, characterized in that... The external electron donor is diphenyldimethoxysilane.

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