Supported catalyst for olefin polymerization

Abstract

The invention discloses a supported catalyst for olefin polymerization, which comprises maleate with a bicyclic structure in a general formula (I) as an internal electron donor, and the catalyst containing the maleate has better activity, stereospecificity and hydrogen regulation sensitivity during propylene (co) polymerization due to the unique space and electron effects of the maleate. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the field of preparation of multiphase supported Ziegler-Natta catalysts, and specifically relates to a supported catalyst for olefin polymerization, and particularly relates to a catalyst for propylene (co)polymerization. Background Art

[0002] Heterogeneous supported Ziegler-Natta catalyst is a solid titanium catalyst composed of magnesium, titanium, halogen and internal and external electron donors as basic components. It is particularly suitable for the polymerization of α-olefins with 3 or more carbon atoms, and the obtained olefin polymer has a high yield and stereoregularity. Among them, the internal electron donor is one of the essential components of the supported Ziegler-Natta catalyst. A large number of studies have proved that the presence of the internal electron donor can effectively improve the polymerization activity and isotacticity of α-olefins catalyzed by the Ziegler-Natta catalyst. Polyolefin catalysts are constantly updated with the development of electron donor compounds.

[0003] At present, dibasic aromatic carboxylic acid ester compounds represented by phthalates are more commonly used in industry (PM Trivedi, et al. J. Polym. Res., 2021, 28, Article number: 45). In addition, a variety of electron donor compounds have been reported in the literature, such as monobasic or polybasic carboxylic acid esters, anhydrides, ketones, monoethers or polyethers, amines, and their derivatives. In recent years, researchers have developed a variety of novel internal electron donors, such as 1,3-diethers (CN1090194C, CN00103538, and CN1137155C), diol esters (WO2011084691A2 and US20110213106A1, US20190338054A1, and CN102325808A), and succinates (WO2002030998, CN101831016A, and CN101423571A). The Ziegler-Natta catalysts loaded with these internal electron donors have significantly improved the polymerization activity, isotacticity, and broad molecular weight distribution of α-olefins. However, whether it is 1,3-diether or diol lipid compounds, the synthesis is difficult and costly, and there has been no industrial report of their separate use.

[0004] Maleate compounds are a common type of bulk chemicals. Researchers have long used them as internal electron donors for olefin catalysts (EP45977). However, the activity of unmodified maleates is often low. For example, patent US5436213 involves unsubstituted maleates and 2-methyl substituted maleates. The activity of the catalyst supported by 2-methyl substituted maleates is significantly improved; the catalyst supported by a monocyclic maleate structure in which the substituents on the 2nd and 3rd carbon atoms are connected to form a ring disclosed in patent JP2014201602A also shows very high activity and isotacticity; in addition, the 2,3-disubstituted condensed ring structure maleate internal electron donors designed by patents CN101824108A and CN101824106A also show higher activity and isotacticity than unsubstituted maleates in the catalysts they support. Summary of the invention

[0005] The present invention provides a catalyst component for the polymerization of CH2=CHR olefins, wherein R is hydrogen or a hydrocarbon group having 1 to 12 carbon atoms. Another object of the present invention is to provide a catalyst containing the above catalyst component.

[0006] The inventors have found through research that maleate containing 7-oxacyclonorbornene structure can be effectively used as an internal electron donor for olefin polymerization catalysts, and the synthesis method of the compound is simple and easy, which is convenient for promotion and application.

[0007] The present invention adopts the following technical solutions to achieve the above invention objectives:

[0008] The present invention provides an olefin polymerization catalyst component, which comprises, by weight percentage, 10% to 25% magnesium, 1% to 10% titanium, 40% to 60% halogen and 1% to 30% internal electron donor, characterized in that the internal electron donor compound is selected from at least one maleate in the general formula (I):

[0009]

[0010] Wherein, the group X is a heteroatom such as oxygen, sulfur or nitrogen, and the groups R1 and R2 are the same or different from each other and are C1 to C 20 a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; the groups R3 to R6 are identical or different from each other and are hydrogen or C1-C 20 A linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms, and two or more groups among R3 to R6 may be bonded to each other to form one or more condensed ring structures.

[0011] Furthermore, in the above technical solution, in the above compound general formula (I), X is preferably an oxygen atom.

[0012] Furthermore, in the above technical solution, in the above compound general formula (I), R1 and R2 are preferably C1 to C 10 An alkyl group, a cycloalkyl group or an arylalkyl group, more preferably a C1-C 10 The alkyl group is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a neopentyl group, and particularly preferably an ethyl group, an isopropyl group, an n-butyl group or an isobutyl group.

[0013] Furthermore, in the above technical solution, in the above compound general formula (I), preferably, at least one of the two groups of R3 and R4; R5 and R6 is hydrogen, and more preferably, all of R3 to R6 are hydrogen.

[0014] Further, in the above technical scheme, the above compound general formula (I) includes but is not limited to: 7-oxabicyclo [2.2.1] hept-2-ene-2,3-dicarboxylic acid dimethyl ester, 7-thiabicyclo [2.2.1] hept-2-ene-2,3-dicarboxylic acid diethyl ester, 7-methyl-7-amine-bicyclo [2.2.1] hept-2-ene-2,3-dicarboxylic acid diisopropyl ester, 7-oxabicyclo [2.2.1] hept-2-ene-2,3-dicarboxylic acid dibutyl ester, 1-methyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid diisobutyl ester, 1,4-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid dineopentanol ester, 5,6-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid neopentyl ester and 1,4,5,6-tetramethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid diisobutyl ester.

[0015] Furthermore, in the above technical scheme, the precursor of the above compound of general formula (I) can be obtained by esterification and Diels-Alder reaction, as shown in CN101824108A. The obtained precursor is hydrogenated in the presence of a multiphase catalyst to obtain an internal electron donor (I). The synthesis route is as follows: The definitions of substituents R1-R6 and X in the structural formula in the following synthesis route are the same as R1-R6 and X in formula (I).

[0016]

[0017] Further, in the above technical scheme, the magnesium halide alcoholate is synthesized according to the literature report (US4399054), and the synthesis of the ethanolate of magnesium chloride is taken as an example. The specific synthesis method is as follows: 24g of anhydrous MgCl2, 390mL of vaseline oil, 50mL of anhydrous ethanol, 10mL of silicone oil and 2mL of Siban are added to a high-pressure reactor at room temperature, and stirred and heated to 130°C for 3 hours under nitrogen protection to completely dissolve the solid. After that, nitrogen is continuously charged into the kettle and the pressure of 1MPa is maintained, and the discharge valve is opened to pass the mixture in the kettle through a capillary tube with a diameter of 1.2mm and a length of 3.54 meters, and washed with hexane 5 times, and dried at room temperature to obtain a spherical MgCl2 ethanolate carrier.

[0018] Further, in the above technical solution, the particle size distribution of magnesium in the catalyst component is 20 to 250 μm, and the catalyst component is provided by a magnesium halide alcoholate having the general formula of Mg(OR′)mM(2-m)·nROH, as shown in the following reaction formula, wherein R′ is C1 to C 20 alkyl, arylalkyl or aryl; M is halogen; m is an integer of 0≤m≤2; n is a decimal or integer of 0<n<6; R is C1~C 20 An alkyl or arylalkyl group.

[0019] Mg(OR′)mM(2-m)+nROH-→Mg(OR′) m M (2-m) ·nROH

[0020] Furthermore, in the above technical scheme, 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.

[0021] Furthermore, in the above technical solution, the titanium in the catalytic component is of the general formula TiA n (OR″) 4-n The compound is provided, wherein R″ is a hydrocarbon group having 1 to 20 carbon atoms; A is a halogen; and n=1 to 4. Specific compounds include: titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tetrabutoxytitanium, tetraethoxytitanium, monochlorotriethoxytitanium, dichlorodiethoxytitanium or trichloromonoethoxytitanium, preferably titanium tetrachloride.

[0022] The present invention provides a method for preparing a catalytic component a, comprising: (1) adding a spherical magnesium halide alcoholate to a titanium compound at -40 to 10°C, reacting for 1 to 4 hours, wherein the molar ratio of magnesium to titanium is 1:5 to 1:50; (2) heating the temperature to 30 to 80°C, adding an inner electron compound, wherein the molar ratio of magnesium to the inner electron donor compound is 2:1 to 15:1; (3) heating the temperature to 100 to 150°C, reacting for 1 to 4 hours; (4) filtering, then adding the same amount of titanium compound as in step (1), reacting at 110 to 130°C for 1 to 4 hours, and filtering, washing, and drying to obtain the catalyst component a.

[0023] The above catalytic components are the main components, and the present invention can further provide a catalyst for olefin polymerization. Specifically comprising:

[0024] (a) a catalyst component a comprising magnesium, titanium, halogen and at least one maleate ester selected from the group consisting of general formula (I);

[0025]

[0026] (b) an alkylaluminum compound;

[0027] (c) optionally, an external electron donor component;

[0028] The usage of each component is 1:5-1000:0-500 based on the molar ratio of titanium:aluminum:external electron donor compound.

[0029] Furthermore, in the above technical solution, the alkylaluminum compound is a trialkylaluminum compound, such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, a mixture of trialkylaluminum and alkylaluminum halide or alkylaluminum hydride, or an alkylaluminumoxane.

[0030] Furthermore, in the above technical solution, the external electron donor can be selectively added as needed. For olefin polymers that need to have very high stereoregularity (such as an isotactic index greater than 99%), it is recommended to add an external electron donor compound.

[0031] Furthermore, in the above technical solution, the external electron donor may be selected to have the general formula R″′ n Si(OR″″) 4-n An organosilicon compound, wherein 0≤n≤3 is an integer; R″′ and R″″ are the same or different alkyl, cycloalkyl or aryl groups, optionally containing heteroatoms; R″′ may also be a halogen or a hydrogen atom.

[0032] 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.

[0033] Furthermore, in the above technical solution, the usage ratio of each component in the catalyst is preferably 1:25-100:25-300, calculated on the molar ratio of titanium:aluminum:external electron donor compound.

[0034] The catalyst of the present invention can be used for olefin polymerization, especially homopolymerization of propylene or copolymerization of propylene with other olefins to obtain polymers with very high isotactic index. At the same time, it is not excluded that the catalyst is suitable for 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.

[0035] When used for propylene polymerization, various methods in the prior art can be used, which can be carried out in liquid phase or gas phase, or in a combination of liquid phase and gas phase polymerization stages. The polymerization is usually carried out at 0 to 150°C, preferably 40 to 90°C. The polymerization pressure is 0.01 to 10 MPa. Hydrogen or other compounds that can act as chain transfer agents can be used to control the molecular weight of the polymer.

[0036] The present invention adopts a maleate compound with a special unsaturated heterocyclic structure as an internal electron donor. Its unique electronic and geometric effects make the catalyst have excellent comprehensive performance. When used for propylene (co)polymerization, a satisfactory polymerization yield can be obtained, and the stereospecificity of the polymer is high. At the same time, the catalyst is also very sensitive to hydrogen regulation. The molecular weight distribution of the obtained polymer is relatively wide, which is conducive to the development of different grades of polymers. DETAILED DESCRIPTION

[0037] The following embodiments are used to further illustrate the present invention, but not to limit the present invention.

[0038] 1. Synthesis of maleate compounds with unique structures

[0039] The maleate of the present invention can be obtained by Diels-Alder reaction and heterogeneous catalytic hydrogenation. Di-n-butyl phthalate (99%) and di-n-butyl succinate (99%) were purchased from TCI (Shanghai).

[0040] Example 1

[0041] Synthesis of 1,4-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid dineopentyl alcohol ester. Add 24.0g 2,5-dimethylfuran and 31.8g butynedioic acid dineopentyl alcohol ester into a 150mL flask, stir and reflux overnight. Column chromatography separation, a colorless and transparent liquid product 1,4-dimethyl-7-oxabicyclo[2.2.1]hept-2,5-diene-2,3-dicarboxylic acid diester 39.4g, yield 90%.

[0042] 36.8 g of 1,4-dimethyl-7-oxabicyclo[2.2.1]hept-2,5-diene-2,3-dicarboxylic acid diester and 200 mg of commercial Pd / C catalyst were placed in a high-pressure reactor, and the air in the reactor was replaced with hydrogen. Finally, 1.0 MPa of hydrogen was introduced and reacted at 50° C. for 2 hours to obtain 37.0 g of oily colorless liquid 1,4-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid dineopentanol ester with a yield of 99%. 1 The H NMR results are shown in Table 1.

[0043] Example 2

[0044] Synthesis of dimethyl 7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylate. The synthesis method is the same as in Example 1, except that 17.0 g of furan and 17.8 g of dimethyl butynedioate are used instead of 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate. The total yield is 95%. 1 The H NMR results are shown in Table 1.

[0045] Example 3

[0046] Synthesis of diethyl 7-thiabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylate. The synthesis method is the same as in Example 1, except that 21.0 g of thiophene and 21.3 g of diethyl butynedioate are used to replace 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate. The total yield is 94%. 1 The H NMR results are shown in Table 1.

[0047] Example 4

[0048] Synthesis of 7-methyl-7-amine-bicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid diisopropyl ester. The synthesis method is the same as that of Example 1, except that 20.3 g of N-methylpyrrole and 24.8 g of diisopropyl butynedioate are used to replace 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate. The total yield is 90%. 1 The H NMR results are shown in Table 1.

[0049] Example 5

[0050] Synthesis of di-n-butyl 7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylate. The synthesis method is the same as that of Example 1, except that 17.0 g of furan and 28.3 g of di-n-butyl butynedioate are used to replace 24.0 g of 2,5-dimethylfuran and 31.8 g of di-neopentyl butynedioate. The total yield is 89%. 1 The H NMR results are shown in Table 1.

[0051] Example 6

[0052] Synthesis of 1-methyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid diisobutyl ester. The synthesis method is the same as that of Example 1, except that 20.5 g of 2-methylfuran and 28.3 g of diisobutyl butynedioate are used to replace 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate. The total yield is 93%. 1 The H NMR results are shown in Table 1.

[0053] Example 7

[0054] Synthesis of 5,6-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid dineopentyl ester. The synthesis method is the same as that of Example 1, except that 24.0 g of 3,4-dimethylfuran and 31.8 g of dineopentyl butynedioate are used to replace 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate. The total yield is 90%. 1 The H NMR results are shown in Table 1.

[0055] Example 8

[0056] The synthesis method is the same as that of Example 1, except that 31.0 g of 2,3,4,5-tetramethylfuran and 28.3 g of diisobutyl butynedioate are used to replace 24.0 g of 2,5-dimethylfuran and 31.8 g of dineopentyl butynedioate. The total yield is 91%. 1 The H NMR results are shown in Table 1.

[0057] Table 1. Internal electron donors 1 HNMR results

[0058]

[0059] 2. Preparation of Catalytic Component A

[0060] TiCl4 was added to a dry glass reactor protected by nitrogen and cooled to -20°C. Microspherical magnesium chloride alcoholate (magnesium alcohol ratio of 2.9:1) carrier was added under stirring. The mixing ratio of carrier and TiCl4 was 1g:20mL. The reaction mixture was heated uniformly from -20°C to 0°C, and then to 70°C. The internal electron donor was added to the reactor, and the reaction mixture was heated to 110°C and continued to react for 2h; filtered, fresh equal amount of TiCl4 was added again, heated to 120°C and continued to react for 2h, filtered, washed the filter cake with hexane, and vacuum dried to obtain the catalyst component. The loading amount of the internal electron donor was determined by Angent 8890A gas chromatograph; the titanium loading amount was determined according to the spectrophotometer.

[0061] 3. Propylene polymerization

[0062] 0.1 mL of external electron donor diphenyldimethoxysilane, 4.0 mL of a hexane solution of a co-catalyst triethylaluminum with a concentration of 1 mol / L, and 0.01 mmol (calculated as titanium) of the catalyst component a prepared by the present invention were added to a 5 L autoclave in sequence, 2.5 L of liquid propylene and 0.2 MPa of hydrogen were introduced, stirred and mixed uniformly at room temperature, heated to 70° C., stirred for reaction for 2 h, the autoclave was opened to take out the polypropylene, and the polymer was cooled to room temperature and weighed after the propylene was completely volatilized, the activity of the catalyst was calculated, and the isotacticity, bulk density, melt index, particle size distribution, molecular weight distribution and other properties of the polypropylene were measured.

[0063] Examples 9-16 used the Ziegler-Natta catalyst synthesized by the internal electron donor in Examples 1-8 and then carried out propylene polymerization using the above-mentioned polymerization steps. The polymerization results are shown in Table 2.

[0064] Table 2. Aggregation results

[0065]

[0066] From the above results, it can be seen that the activity and isotacticity of the synthesized catalyst with maleate as internal electron donor in catalyzing propylene polymerization are significantly better than those of the commercial di-n-butyl phthalate and di-n-butyl maleate supported catalysts.

Claims

1. A supported catalyst for olefin polymerization, comprising, by weight percentage, 10% to 25% magnesium, 1% to 10% titanium, 40% to 60% halogen and 1% to 30% internal electron donor, characterized in that The internal electron donor compound is selected from at least one maleate in the general formula (I): Wherein the group X is an oxygen, sulfur or nitrogen heteroatom, the groups R1 and R2 are the same or different from each other and are selected from C1 to C 20 a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; the groups R3, R4, R5, R6 are identical or different and are selected from hydrogen or C1-C 20 A linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms, and two or more groups among R3, R4, R5 and R6 can be bonded to each other to form one or more condensed ring structures.

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

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

4. The catalyst according to claim 1, characterized in that The internal electron donor compound of general formula (I) is selected from the group consisting of dimethyl 7-oxabicyclo [2.2.1] hept-2-ene-2,3-dicarboxylate, diethyl 7-thiabicyclo [2.2.1] hept-2-ene-2,3-dicarboxylate, diisopropyl 7-methyl-7-amine-bicyclo [2.2.1] hept-2-ene-2,3-dicarboxylate, di-n-butyl 7-oxabicyclo [2.2.1] hept-2-ene-2,3-dicarboxylate, 1-methyl-7-oxabicyclo [2.2.1] hept-2-ene-2,3-dicarboxylate, 1,4-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid diisobutyl ester, 1,4-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid dineopentyl ester, 5,6-dimethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid neopentyl ester and 1,4,5,6-tetramethyl-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylic acid diisobutyl ester.

5. The catalyst according to claim 1, characterized in that The particle size distribution of magnesium in the catalyst component is 20 to 250 μm, and the general formula is Mg(OR') m M (2-m) ·nROH is provided by a magnesium halide alcoholate, wherein R' is C1~C 20 alkyl, arylalkyl or aryl; M is 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 of C1-C 20 alkyl or aralkyl; The titanium in the catalytic component is represented by the general formula TiA n (OR”) 4-n A compound is provided, wherein R" is a hydrocarbon group having 1 to 20 carbon atoms; A is a halogen; and n=1 to 4.

6. The catalyst according to claim 5, characterized in that A magnesium halide alcoholate of magnesium is provided, wherein the magnesium halide is one of magnesium dichloride, magnesium dibromide, chloromethoxymagnesium or chloroethoxymagnesium; and the alcohol in the magnesium halide alcoholate is one of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol; The titanium in the catalytic component is provided by titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxide, titanium tetraethoxide, titanium triethoxide monochloride, titanium diethoxide dichloride or titanium trichloride-ethoxide.

7. A catalyst characterized in that The catalyst comprises: (a) the catalyst according to any one of claims 1 to 6; (b) an alkylaluminum compound; (c) optionally, an external electron donor component; The usage of each component is 1:5-1000:0-500 based on the molar ratio of titanium:aluminum:external electron donor compound.

8. The catalyst according to claim 7, characterized in that The alkylaluminum compound is a trialkylaluminum compound; The external electron donor is of the general formula R' n Si(OR””) 4-n An organosilicon compound, wherein n is an integer of 0≤n≤3; R'' and R"" are the same or different alkyl, cycloalkyl or aryl groups.

9. The catalyst according to claim 8, characterized in that The alkylaluminum compound is triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, a mixture of a trialkylaluminum and an alkylaluminum halide or an alkylaluminum hydride, or an alkylaluminumoxane; The external electron donor is selected from trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, cyclohexylmethyldimethoxysilane, methyl-tert-butyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, di-n-butyldimethoxysilane, dicyclopentyldimethoxysilane or di(cyclobutylmethyl)dimethoxysilane, preferably dicyclopentyldimethoxysilane.

10. The catalyst according to claim 15, wherein the amount ratio of each component in the catalyst is preferably 1:25-100:25-300, calculated on the molar ratio of titanium:aluminum:external electron donor compound.

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