Supported metallocene catalyst

Abstract

The invention discloses a supported metallocene catalyst. The supported metallocene catalyst is prepared from the following components: a metallocene compound, aluminum alkyl fluoride, polysilsesquioxane and silica gel, the general formula I of the metallocene compound is Cp * 2 (Z) MXn1; the general formula II of the aluminum alkyl fluoride is Fn2Al (R1) 3-n2, R1 represents C1-C20 alkyl, and n2 is greater than or equal to 1 and less than or equal to 3. The particle morphology of the supported metallocene catalyst is good, and the particle size of the supported metallocene catalyst is adjustable. The supported metallocene catalyst provided by the invention has very high ethylene polymerization catalytic activity.

Description

Technical Field

[0001] The present invention belongs to the field of olefin polymerization catalysts, and particularly relates to a supported metallocene catalyst, and more particularly to a supported metallocene catalyst that does not require the addition of methylaluminoxane (MAO). Background Art

[0002] The development and application of metallocene catalysts is another major breakthrough in the field of olefin polymerization catalysts after the traditional Ziegler-Natta catalysts. Especially in the 1980s, Kaminsky, Sinn and others (Angew. Chem., 1980, 19, 390; Adv. Organoment. Chem., 1980, 18, 99) developed an efficient cocatalyst methylaluminoxane (MAO), which made the research of metallocene catalysts enter a rapid development stage. However, the amount of MAO required for metallocene catalysts to achieve high activity is large, and the production cost is high, which limits the further wide application of metallocene catalysts in the field of olefin polymerization.

[0003] Two types of methods are usually used to solve the above problems. The most common one is to modify the surface of the support with MAO, that is, to load MAO, so that homogeneous MAO solution does not need to be added during the polymerization process. There are many research reports on the modification of the support with MAO, and the research reports on the modification of silica gel support with MAO are the most. Such as CN200910235933.8; CN201010519660.2; CN201110336517.4; CN201210418645.8; CN201310521768.9; US6,777,366; US7,294,600; US8,436,112; US10,233,268. Although this method avoids the addition of homogeneous MAO solution during the polymerization process, there is still loss of MAO solution during the modification process of the silica gel support, and the cost needs to be reduced by increasing the recycling process (such as CN02104332.9; Petrochemical Technology & Application, 2003, 21: 170-173), but this method makes the process more complicated.

[0004] Another method is to use borides as cocatalysts instead of MAO, including boron trihalides, trifluorophenylboron, organic borates, etc. Chinese invention patent CN201310541010.1 discloses a supported metallocene catalyst for ethylene polymerization, which catalyst comprises the reaction product of the following components: (1) a metallocene compound; (2) a chlorinated hydrocarbylsilane; (3) an alkylaluminum; (4) a borate compound; (5) a silica support. The N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate compound used acts as a substitute for MAO as a cocatalyst, but these borate compounds cannot directly bond with the functional groups on the surface of the support. Instead, the support needs to be modified successively with chlorinated hydrocarbylsilane, alkylaluminum, etc. before the borate compound can be loaded, and the reaction steps are numerous.

[0005] Chinese invention patent CN115651101A discloses a supported metallocene catalyst for ethylene polymerization, which catalyst comprises: (1) a metallocene compound; (2) a silica support modified with aluminum and fluorine. MAO is not required during the preparation process and the polymerization process of this supported metallocene catalyst, greatly reducing the production cost. However, the preparation process of this catalyst is complex. The method of "modifying with alkylaluminum + thermal calcination in a nitrogen atmosphere + thermal calcination in an oxygen atmosphere + thermal calcination with the addition of a fluorination modification reagent" is adopted. Among them, alkylaluminum and the fluorination reagent are used step by step, and multiple high-temperature calcination operations are included during the addition of the two. Finally, the amount of the fluorination reagent added is large but most of it is decomposed by heating, resulting in a small F content, a low F / Al molar ratio, and insignificant improvement in activity. At the same time, the above problems are not suitable for solution by further increasing the amount of the fluorination reagent because the decomposition product HF of the fluorination reagent has a corrosive effect on the silica support skeleton and reduces its strength, so its further application will be limited. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a metallocene catalyst supported by polyhedral oligomeric silsesquioxane / fluorinated alkylaluminum / silica gel. After the silica gel is subjected to heat treatment, polyhedral oligomeric silsesquioxane treatment, and fluorinated alkylaluminum modification, it can be used to support the metallocene catalyst. Polyhedral oligomeric silsesquioxane, fluorinated alkylaluminum, and silica gel together constitute an efficient modified support. Among them, polyhedral oligomeric silsesquioxane can not only bind to the hydroxyl groups on the silica gel through alkoxy or silyl groups, but also contain hydroxyl groups that can bind to fluorinated alkylaluminum. It can not only play a role in stabilizing the F element and increasing the F content in the support, but also make the distance between the F modification site and the metal active center closer. At the same time, the F element does not directly contact the silica gel, reducing the possibility of decomposing HF to corrode the silica gel skeleton. Finally, the metallocene compound is supported by the "fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel" modified support, significantly improving the catalytic activity.

[0007] To achieve the above purpose, the present invention provides a supported metallocene catalyst, which supported metallocene catalyst comprises the following components:

[0008] (1) Metallocene compound; (2) Fluoroalkylaluminum; (3) Polyhedral oligomeric silsesquioxane; and (4) Silica support;

[0009] The general formula I of the metallocene compound is Cp* 2 (Z)MX n1 , where Cp* is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group, and the substituent is selected from C 1 -C 20 alkyl, alkoxy, silyl, aralkoxy or halogen; Z is a linking unit connecting two metallocene rings. If the general formula I is a non-bridged metallocene complex, then Z does not represent any element; if the general formula I is a bridged metallocene complex, then Z is selected from SiR* 2 , CR* 2 , SiR* 2 SiR* 2 , CR* 2 CR* 2 , CR*=CR*, or CR* 2 SiR* 2 , where R* is hydrogen or an alkyl, aryl, silyl, haloalkyl or haloaryl group with less than 20 carbon atoms; M is a transition metal of Group 4 or Group 5 in the periodic table; X is the same or different and is selected from one of halogen, hydrocarbon group, hydrocarbonoxy group, acid radical, amino group; n1 is an integer satisfying the valence state of M;

[0010] The general formula II of the fluoroalkylaluminum is F n2 Al(R 1 ) 3-n2 , where R 1 represents a C 1 -C 20 hydrocarbon group, 1≤n2≤3;

[0011] In general formula 1, M is preferably zirconium or hafnium, and X in general formula I is selected from halogen, hydrocarbon group, allyl group, cyclopentadienyl group, alkoxy group, areneoxy group, most preferably chlorine, bromine, methyl, ethyl, methoxy, or isopropoxy; preferably n1 = 2.

[0012] For the supported metallocene catalyst of the present invention, the proportions of the components in the supported metallocene catalyst are as follows: based on per gram of silica, the addition amount of fluoroalkylaluminum is 0.1-10 mmol, the addition amount of polyhedral oligomeric silsesquioxane is 0.01-1 mmol, and the addition amount of metallocene compound is 10-500 μmol.

[0013] For the supported metallocene catalyst of the present invention, the weight content of aluminum in the supported metallocene catalyst is 1-30%, preferably 5-15%; the weight content of metal M is 0.01-5%, preferably 0.1-1%.

[0014] For the supported metallocene catalyst of the present invention, in the general formula I, X is selected from halogen, hydrocarbyl, allyl, cyclopentadienyl, alkoxy, and aryloxy.

[0015] For the supported metallocene catalyst of the present invention, in the general formula I, n1 = 2.

[0016] For the supported metallocene catalyst of the present invention, in the general formula I, M is zirconium or hafnium.

[0017] For the supported metallocene catalyst of the present invention, the fluorinated alkylaluminum is selected from at least one of diethylaluminum fluoride, ethylaluminum difluoride, dipropylaluminum fluoride, propylaluminum difluoride, diisopropylaluminum fluoride, ethylpropylaluminum fluoride, and aluminum trifluoride.

[0018] The second object of the present invention is to provide a preparation method of a supported metallocene catalyst, and the preparation method includes the following steps:

[0019] (1) Thermal activation treatment of silica gel: Under vacuum, heat the silica gel to obtain thermally activated silica gel;

[0020] (2) Treatment of silica gel with polyhedral oligomeric silsesquioxane: Under the protection of an inert gas, add the thermally activated silica gel obtained in step (1) to a reactor, add a solvent, disperse it into a suspension, slowly add a polyhedral oligomeric silsesquioxane solution, raise the temperature, stir and react, then wash with the solvent several times and dry to obtain silica gel treated with polyhedral oligomeric silsesquioxane;

[0021] (3) Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support: Under the protection of an inert gas, add the silica gel treated with polyhedral oligomeric silsesquioxane obtained in step (2) to a reactor, add a solvent, disperse it into a suspension, slowly add a fluorinated alkylaluminum solution, raise the temperature to react, stir, then wash with the solvent several times and dry to obtain a fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support;

[0022] (4) Preparation of supported metallocene catalyst: Under the protection of an inert gas, add the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support obtained in step (3) to a solvent to form a slurry, dropwise add a metallocene compound solution to the slurry, react, wash with the solvent and dry to obtain a supported metallocene catalyst.

[0023] For the preparation method of the supported metallocene catalyst of the present invention, in step (1), the heating temperature is 200 - 600 °C, preferably 400 - 500 °C, and the reaction time is 1 - 24 hours, preferably 6 - 10 hours.

[0024] The preparation method of the supported metallocene catalyst of the present invention. In step (2), the temperature of the reaction is 0-90 °C, preferably 30-60 °C, and the reaction time is 1-24 hours, preferably 2-4 hours; the solvent is at least one of toluene, benzene, xylene, hexane, heptane, cyclohexane; preferably toluene.

[0025] The preparation method of the supported metallocene catalyst of the present invention. In step (3), the temperature of the reaction is 0-90 °C, preferably 30-60 °C, and the reaction time is 1-24 hours, preferably 2-4 hours; the solvent is at least one of toluene, benzene, xylene, hexane, heptane, cyclohexane; preferably toluene.

[0026] The preparation method of the supported metallocene catalyst of the present invention. In step (4), the temperature of the reaction is 0-90 °C, preferably 20-40 °C, and the reaction time is 0.5-12 hours, preferably 1-2 hours; the solvent is at least one of toluene, benzene, xylene, hexane, heptane, cyclohexane, preferably toluene, hexane or a mixture of the two.

[0027] The third object of the present invention is to provide the application of the supported metallocene catalyst in the polymerization reaction.

[0028] In the application of the present invention, the polymerization reaction is a gas-phase polymerization or a slurry polymerization.

[0029] In the application of the present invention, the polymerization reaction is a homopolymerization or copolymerization reaction of olefins, and is particularly suitable for the homopolymerization of ethylene or the copolymerization reaction of ethylene and other α-olefins.

[0030] In the application of the present invention, the α-olefin is selected from at least one of propylene, butene, pentene, hexene, octene, 4-methylpentene-1.

[0031] In the application of the present invention, the solvent used in the polymerization reaction is selected from alkanes, aromatic hydrocarbons or halogenated hydrocarbons. Preferably at least one of hexane, pentane, heptane, benzene, toluene, dichloromethane, chloroform, dichloroethane, and most preferably one or a mixture of hexane, toluene, and heptane.

[0032] In the application of the present invention, the concentration of the supported metallocene catalyst in the polymerization reaction is 1×10 -8 mol / L - 1×10 -3 mol / L, preferably the concentration range is 1×10 -8 mol / L - 1×10 -5 mol / L.

[0033] In the application of the present invention, the temperature of the polymerization reaction is -78 °C - 100 °C, preferably 0 °C - 90 °C.

[0034] For the application of the present invention, the pressure of the polymerization reaction is 0.01 - 10.0 MPa, preferably 0.01 - 2.0 MPa.

[0035] The supported metallocene catalyst of the present invention has good particle morphology, and the particle size of the supported metallocene catalyst can be adjusted. The supported metallocene catalyst of the present invention has high ethylene polymerization catalytic activity. The supported metallocene catalyst of the present invention has good catalytic copolymerization activity for ethylene and higher α-olefins, and the copolymerization activity is high. The supported metallocene catalyst of the present invention does not use MAO during the polymerization process, greatly reducing the production cost. The resin powder obtained by using the supported metallocene catalyst of the present invention for olefin polymerization has good particle morphology and high bulk density, and can be applied to slurry polymerization and gas-phase polymerization processes. Detailed implementation manners

[0036] The following examples are more detailed illustrative descriptions of the present invention, but the present invention is not limited to these examples.

[0037] Testing methods:

[0038] 1. ICP (Inductively Coupled Plasma Emission Spectrometry) characterization: Quantitatively determine the weight percentage of metals in the supported catalyst. The instrument used is the P1000 type ICP-AES inductively coupled plasma emission spectrometer produced by PE Company of the United States.

[0039] 2. Characterization of polymer molecular weight and molecular weight distribution: The molecular weight and its distribution are determined by gel permeation chromatography (GPC). The instrument used is Agilent PL220, the solvent is 1,2,4-trichlorobenzene, the sample concentration is 1 mg / mL, and the solvent flow rate is 1.0 mL / min; the measurement temperature is 150 °C, and each sample is measured twice.

[0040] Example 1:

[0041] (1) Thermal activation treatment of silica gel

[0042] Heat 955 silica gel under vacuum, raise the temperature from 20 °C to 200 °C at a heating rate of 10 °C / min. After reaching 200 °C, hold for 24 hours to obtain the thermally activated silica gel.

[0043] (2) Treatment of silica gel with polyhedral oligomeric silsesquioxane:

[0044] Under nitrogen protection, 2.0 g of the thermally activated silica gel obtained in step (1) was added to a glass reactor, 80 mL of dried toluene was added, dispersed into a suspension, 0.5 mL of a 1 mmol / mL polyhedral oligomeric silsesquioxane toluene solution was added, the temperature was raised to 90 °C, and the mixture was stirred and reacted for 1 hour. Then it was washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely polyhedral oligomeric silsesquioxane-treated silica gel.

[0045] (3) Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support

[0046] Under nitrogen protection, 2.0 g of the polyhedral oligomeric silsesquioxane-treated silica gel obtained in step (2) was added to a glass reactor, 80 mL of dried toluene was added, dispersed into a suspension, 0.5 mL of a 10 mmol / mL difluoroethylaluminum toluene solution was added, the temperature was raised to 90 °C, and the mixture was stirred and reacted for 1 hour. Then it was washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support.

[0047] (4) Preparation of supported metallocene catalyst A

[0048] Under nitrogen protection, 1 g of the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support obtained in step (3) was added to a glass reactor, 20 mL of dried toluene was added to make a slurry, and 40.4 mg of bis-(n-butylcyclopentadienyl)zirconium dichloride (nBuCp) 2 ZrCl 2 dissolved in 10 mL of toluene was added dropwise to the reactor, and the reaction was carried out at 40 °C for 12 hours. Then it was washed with 20 mL of toluene and dried under vacuum to obtain supported metallocene catalyst A. Characterized by ICP, in catalyst A, the Zr weight content was 0.56%, the Al weight content was 5.89%, and the F weight content was 13.56%.

[0049] Example 2:

[0050] (1) Thermal activation treatment of silica gel

[0051] The 955 silica gel was heated under vacuum, heated from 20 °C to 450 °C at a heating rate of 10 °C / min. After reaching 450 °C, it was maintained for 8 hours to obtain thermally activated silica gel.

[0052] (2) Preparation of polyhedral oligomeric silsesquioxane-treated silica gel

[0053] Under nitrogen protection, 2.0 g of the thermally activated silica gel obtained in step (1) was added to a glass reactor, 80 mL of dried toluene was added, dispersed into a suspension, 0.5 mL of a 1 mmol / mL polyhedral oligomeric silsesquioxane toluene solution was added, the temperature was raised to 40 °C, and the mixture was stirred and reacted for 2 hours. It was washed three times with 60 mL of toluene and once with 60 mL of hexane, and then dried under vacuum to obtain a solid powder with good fluidity, namely polyhedral oligomeric silsesquioxane-treated silica gel.

[0054] (3) Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support

[0055] Under nitrogen protection, 2.0 g of the polyhedral oligomeric silsesquioxane-treated silica gel obtained in step (2) was added to a glass reactor, 80 mL of dried toluene was added, dispersed into a suspension, 0.5 mL of a 10 mmol / mL diethylaluminum fluoride toluene solution was added, the temperature was raised to 40 °C, and the mixture was stirred and reacted for 2 hours. It was washed three times with 60 mL of toluene and once with 60 mL of hexane, and then dried under vacuum to obtain a solid powder with good fluidity, namely fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support.

[0056] (4) Preparation of supported metallocene catalyst B

[0057] Under nitrogen protection, 1 g of the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support obtained in step (3) was added to a glass reactor, 20 mL of dried toluene was added to make a slurry, and 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 dissolved in 10 mL of toluene was added dropwise to the reactor. The reaction was carried out at 25 °C for 1 hour, then washed with 20 mL of toluene and dried under vacuum to obtain supported metallocene catalyst B. By ICP characterization, in catalyst B, the Zr weight content was 0.33%, the Al weight content was 14.71%, and the F weight content was 10.71%.

[0058] Example 3:

[0059] (1) Thermal activation treatment of silica gel

[0060] The 955 silica gel was heated under vacuum, heated from 20 °C to 600 °C at a heating rate of 10 °C / min. After reaching 600 °C, it was held for 1 hour to obtain thermally activated silica gel.

[0061] (2) Preparation of polyhedral oligomeric silsesquioxane-treated silica gel

[0062] Under nitrogen protection, 2.0 g of the thermally activated silica gel obtained in step (1) was added to a glass reactor, 80 mL of dried toluene was added, and it was dispersed into a suspension. 1 mL of a toluene solution of polyhedral oligomeric silsesquioxane with a concentration of 0.1 mmol / mL was added, the temperature was lowered to 0 °C, and the mixture was stirred and reacted for 24 hours. Then it was washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely polyhedral oligomeric silsesquioxane-treated silica gel.

[0063] (3) Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support

[0064] Under nitrogen protection, 2.0 g of the polyhedral oligomeric silsesquioxane-treated silica gel obtained in step (2) was added to a glass reactor, 80 mL of dried toluene was added, and it was dispersed into a suspension. 1 mL of a toluene solution of dipropylaluminum fluoride with a concentration of 1 mmol / mL was added, the temperature was lowered to 0 °C, and the mixture was stirred and reacted for 24 hours. Then it was washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support.

[0065] (4) Preparation of supported metallocene catalyst C

[0066] Under nitrogen protection, 1 g of the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support obtained in step (3) was added to a glass reactor, 20 mL of dried toluene was added to make a slurry, and 52.1 mg of bis(1,3-butylmethylcyclopentadienyl)hafnium dichloride (1,3-BuMeCp) 2 HfCl 2 dissolved in 10 mL of toluene was added dropwise to the reactor, and the reaction was carried out at 0 °C for 12 hours. Then it was washed with 20 mL of toluene and dried under vacuum to obtain supported metallocene catalyst C. Characterized by ICP, in catalyst C, the weight content of Hf is 0.13%, the weight content of Al is 1.58%, and the weight content of F is 3.11%.

[0067] Example 4:

[0068] (1) Thermal activation treatment of silica gel

[0069] The 955 silica gel was heated under vacuum, heated from 20 °C to 350 °C at a heating rate of 10 °C / min. After reaching 350 °C, it was maintained for 10 hours to obtain thermally activated silica gel.

[0070] (2) Preparation of polyhedral oligomeric silsesquioxane-treated silica gel

[0071] Under nitrogen protection, 2.0 g of the heat-activated silica gel obtained in step (1) was added to a glass reactor, 80 mL of dried toluene was added, dispersed into a suspension, 1 mL of a 1 mmol / mL polyhedral oligomeric silsesquioxane toluene solution was added, the temperature was raised to 50 °C, and the mixture was stirred and reacted for 4 hours. Then it was washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely polyhedral oligomeric silsesquioxane-treated silica gel.

[0072] (3) Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support

[0073] Under nitrogen protection, 2.0 g of the heat-activated silica gel obtained in step (2) was added to a glass reactor, 80 mL of dried toluene was added, dispersed into a suspension, 1 mL of a 10 mmol / mL diisopropylaluminum fluoride toluene solution was added, the temperature was raised to 50 °C, and the mixture was stirred and reacted for 4 hours. Then it was washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support.

[0074] (4) Preparation of supported metallocene catalyst D

[0075] Under nitrogen protection, 1 g of the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support obtained in step (3) was added to a glass reactor, 20 mL of dried toluene was added to make a slurry, and 41.8 mg of ethylene bis(1-indenyl)zirconium dichloride CH 2 (Ind) 2 ZrCl 2 dissolved in 10 mL of toluene was added dropwise to the reactor. The reaction was carried out at 40 °C for 2 hours, then washed with 20 mL of toluene, and dried under vacuum to obtain supported metallocene catalyst D. By ICP characterization, in catalyst D, the Zr weight content was 0.91%, the Al weight content was 20.13%, and the F weight content was 17.62%.

[0076] Example 5:

[0077] (1) Thermal activation treatment of silica gel

[0078] Same as step (1) in Example 2.

[0079] (2) Preparation of polyhedral oligomeric silsesquioxane-treated silica gel

[0080] Same as step (2) in Example 2.

[0081] (3) Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support

[0082] Same as step (3) in Example 2.

[0083] (4) Preparation of Supported Metallocene Catalyst E

[0084] Following the steps of Example 2(4), only replace 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 with 4.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 , to obtain supported metallocene catalyst E. Characterized by ICP, in catalyst E, the weight content of Zr is 0.04%, the weight content of A1 is 12.14%, and the weight content of F is 8.27%.

[0085] Example 6:

[0086] (1) Thermal activation treatment of silica gel

[0087] Same as step (1) in Example 2.

[0088] (2) Preparation of poly(silsesquioxane)-treated silica gel

[0089] Same as step (2) in Example 2.

[0090] (3) Preparation of fluorinated alkylaluminum / poly(silsesquioxane) / silica gel support

[0091] Same as step (3) in Example 2.

[0092] (4) Preparation of supported metallocene catalyst F

[0093] Following the steps of Example 2(4), only replace 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 with 216.5 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 , to obtain supported metallocene catalyst F. Characterized by ICP, in catalyst F, the weight content of Zr is 4.92%, the weight content of A1 is 9.87%, and the weight content of F is 7.14%.

[0094] Comparative Example 1:

[0095] (1) Thermal activation treatment of silica gel

[0096] Same as step (1) in Example 2.

[0097] (2) Preparation of poly(silsesquioxane)-treated silica gel

[0098] Same as step (2) in Example 2.

[0099] (3) Preparation of supported metallocene catalyst G

[0100] Under nitrogen protection, 1 g of the silica gel treated with polyhedral oligomeric silsesquioxane obtained in step (2) was added to a glass reactor, and 20 mL of dried toluene was added to form a slurry. A solution of 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 dissolved in 10 mL of toluene was added dropwise to the reactor. The reaction was carried out at 25 °C for 1 h, then washed with 20 mL of toluene and dried in vacuo to obtain supported metallocene catalyst G. Characterized by ICP, in catalyst G, the weight content of Zr was 0.24%.

[0101] Comparative Example 2:

[0102] (1) Thermal activation treatment of silica gel

[0103] Same as step (1) in Comparative Example 1.

[0104] (2) Preparation of fluorinated alkylaluminum / silica gel support

[0105] Under nitrogen protection, 2.0 g of the thermally activated silica gel obtained in step (1) was added to a glass reactor, 80 mL of dried toluene was added to disperse it into a suspension, 0.5 mL of 10 mmol / mL toluene solution of diethylaluminum fluoride was added, the temperature was raised to 40 °C, and the reaction was stirred for 2 h. It was washed three times with 60 mL of toluene and once with 60 mL of hexane, and dried in vacuo to obtain a solid powder with good fluidity, namely fluorinated alkylaluminum / silica gel support.

[0106] (3) Preparation of supported metallocene catalyst H

[0107] Under nitrogen protection, 1 g of the fluorinated alkylaluminum / silica gel support obtained in step (2) was added to a glass reactor, 20 mL of dried toluene was added to form a slurry. A solution of 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 dissolved in 10 mL of toluene was added dropwise to the reactor. The reaction was carried out at 25 °C for 1 h, then washed with 20 mL of toluene and dried in vacuo to obtain supported metallocene catalyst H. Characterized by ICP, in catalyst H, the weight content of Zr was 0.27%, the weight content of Al was 8.42%, and the weight content of F was 6.54%.

[0108] Comparative Example 3:

[0109] Take 0.5 mL of a toluene solution of diethylaluminum fluoride at 10 mmol / mL and mix it with 0.5 mL of a toluene solution of polyhedral oligomeric silsesquioxane at 1 mmol / mL. Heat the mixture to 40 °C and stir for 2 hours. Then add a solution of 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 dissolved in 10 mL of toluene dropwise into the reactor and react at 25 °C for 1 hour to obtain metallocene catalyst I. Use the unloaded metallocene catalyst I to catalyze ethylene polymerization, and the results are shown in Table 1.

[0110] Comparative Example 4:

[0111] Prepare the supported metallocene catalyst J according to Example 2 of Chinese Patent CN115651101A. By ICP characterization, in catalyst J, the weight content of Zr is 0.40%, the weight content of Al is 6.86%, and the weight content of F is 4.17%.

[0112] High-pressure ethylene polymerization test

[0113] In a 1-L stainless-steel high-pressure polymerization autoclave, replace it with nitrogen and ethylene three times each, then add 2 L of hexane solvent. Along with the addition of hexane, add 4 mL of a hexane solution of triethylaluminum (TEA) at 1 mol / L and the required amount of 1-hexene. Then add 15 mg of the catalyst prepared in the above examples and comparative examples, heat to 85 °C, raise the pressure to and maintain 1.0 MPa, and react for 2 hours. After the polymerization reaction is completed, cool down, collect the polyethylene particle powder, and weigh it. The specific polymerization results are listed in Table 1.

[0114] Table 1 Polymerization results of catalysts

[0115]

[0116]

[0117] As can be seen from Table 1, after the catalyst support is successively treated with polyhedral oligomeric silsesquioxane and modified with fluorinated alkylaluminum, the metallocene supported on the "fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel" support has achieved a significant improvement in catalytic activity. Compared with the support without fluorinated alkylaluminum modification, the polymerization activity after loading the metallocene catalyst has increased by 3 - 9 times. Compared with the support without polyhedral oligomeric silsesquioxane treatment, the polymerization activity after loading the metallocene catalyst has increased by 50% - 120%. At the same time, the addition of polyhedral oligomeric silsesquioxane increases the content and stability of the F element, and thus improves the activity. Compared with the support treated by the multi-step treatment of "alkylaluminum + thermal calcination in nitrogen atmosphere + thermal calcination in oxygen atmosphere + thermal calcination with the addition of fluorinating reagent", using the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel modified support can increase the catalyst activity by more than 70% - 150%.

[0118] The above specific embodiments are illustrative examples of the spirit of the present invention, and the principles and implementation manners of the present invention are elaborated in detail to facilitate those skilled in the art to understand and apply the present invention more accurately. It should be noted that the present invention is not limited to the above specific implementation manners, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the claims of the present invention.

Claims

1. A supported metallocene catalyst, characterized in that, the supported metallocene catalyst comprises the following components: (1) a metallocene compound; (2) a fluorinated alkylaluminum; (3) a polyhedral oligomeric silsesquioxane; and (4) silica gel; The general formula I of the metallocene compound is Cp* 2 (Z)MX n1 , where Cp* is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group, and the substituent is selected from C 1 -C 20 alkyl, alkoxy, silyl, aralkoxy or halogen; Z is a linking unit connecting two metallocene rings. If the general formula I is a non-bridged metallocene complex, Z does not represent any element; If the general formula I is a bridged metallocene complex, then Z is selected from SiR* 2 , CR* 2 , SiR* 2 SiR* 2 , CR* 2 CR* 2 , CR*=CR*, or CR* 2 SiR* 2 , where R* is hydrogen or an alkyl, aryl, silyl, haloalkyl, or haloaryl group having less than 20 carbon atoms; M is a transition metal of Group 4 or Group 5 of the periodic table; X is the same or different and is selected from one of halogen, hydrocarbon group, hydrocarbonoxy group, acid radical, and amino group; n1 is an integer satisfying the valence state of M; The general formula II of the alkyl aluminum fluoride is F n2 Al(R 1 ) 3-n2 , where R 1 represents a C 1 -C 20 hydrocarbyl group, and 1 ≤ n2 ≤ 3.

2. The supported metallocene catalyst according to claim 1, characterized in that, the proportions of the components in the supported metallocene catalyst are as follows: based on each gram of silica gel, the addition amount of the fluorinated alkylaluminum is 0.1 - 10 mmol, the addition amount of the polyhedral oligomeric silsesquioxane is 0.01 - 1 mmol, and the addition amount of the metallocene compound is 10 - 500 μmol.

3. The supported metallocene catalyst according to claim 1, characterized in that, the aluminum content in the supported metallocene catalyst is 1 - 30 wt%, and the content of metal M is 0.01 - 5 wt%.

4. The supported metallocene catalyst according to claim 1, characterized in that, the aluminum content in the supported metallocene catalyst is 5 - 15 wt%, and the content of metal M is 0.1 - 1 wt%.

5. The supported metallocene catalyst according to claim 1, characterized in that, in the general formula I, X is selected from halogen, hydrocarbyl, allyl, cyclopentadienyl, alkoxy, and aryloxy.

6. The supported metallocene catalyst according to claim 1, characterized in that, in the general formula I, n1 = 2.

7. The supported metallocene catalyst according to claim 1, characterized in that, in the general formula I, M is zirconium or hafnium.

8. A supported metallocene catalyst for ethylene polymerization according to claim 1, characterized in that, the fluorinated alkylaluminum is selected from at least one of diethylaluminum fluoride, difluoroethylaluminum, dipropylaluminum fluoride, difluoropropylaluminum, diisopropylaluminum fluoride, ethylpropylaluminum fluoride, and aluminum trifluoride.

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