Supported metallocene catalyst, preparation method and application

Abstract

The invention discloses a supported metallocene catalyst as well as a preparation method and application thereof. According to the preparation method, polysilsesquioxane and aluminum alkyl fluoride are sequentially used for modifying a silica gel carrier, and then a metallocene catalyst is loaded. Wherein polysilsesquioxane not only can be combined with hydroxyl on silica gel through alkoxy or silane bond, but also contains hydroxyl which can be combined with aluminum alkyl fluoride, so that not only can an F element be stabilized and the content of F in the carrier be increased, but also the distance between an F modification site and a metal active center is closer. Meanwhile, the F element is not in direct contact with the silica gel, so that the possibility that HF is decomposed to corrode a silica gel skeleton is reduced. Finally, the metallocene compound is loaded by using the aluminum alkyl fluoride / polysilsesquioxane / silica gel modified carrier, so that the catalytic activity is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of olefin polymerization catalysts, and particularly relates to a supported metallocene catalyst, a preparation method and an application thereof. 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 the development of the highly efficient cocatalyst methylaluminoxane (MAO) has enabled the research of metallocene catalysts to enter a stage of rapid development. However, the large amount of MAO required for metallocene catalysts to achieve high activity results in high production costs, which limits the further widespread application of metallocene catalysts in the field of olefin polymerization.

[0003] Two types of methods are usually adopted to solve the above problems. The most common one is to modify the surface of the support with MAO, that is, to load MAO. In this way, homogeneous MAO solution does not need to be added during the polymerization process. There are many research reports on the modification of supports with MAO, and among them, the research reports on the modification of silica gel supports with MAO are the most. Although this method avoids adding homogeneous MAO solution during the polymerization process, there is still loss of MAO solution during the modification process of silica gel supports, and the cost needs to be reduced by increasing the recycling process. However, this method makes the process more complicated.

[0004] Another method is to use borides to replace MAO as the cocatalyst, including boron trihalides, trifluorophenylboron, organic borates, etc. By using borides, the role of MAO as a cocatalyst is replaced. However, these borides cannot be directly bonded to the functional groups on the surface of the support, but the support needs to be modified successively with chlorinated hydrocarbon-based silicon, alkylaluminum, etc. before the borate compound can be loaded, and the reaction steps are numerous.

[0005] CN115651101A discloses a supported metallocene catalyst for ethylene polymerization, and this catalyst includes: (1) a metallocene compound; (2) a silica gel support modified with aluminum and fluorine. MAO is not required during the preparation process and the polymerization process of this supported metallocene catalyst, which greatly reduces the production cost. However, the preparation process of this catalyst is complex, and the method of "modification 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 to be solved 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 gel support skeleton and reduces its strength, so its further application will be limited. Summary of the Invention

[0006] The object of the present invention is to provide a supported metallocene catalyst, a preparation method and an application thereof, specifically a supported metallocene catalyst for ethylene polymerization or ethylene / α-olefin copolymerization, a preparation method and an application in olefin polymerization reaction.

[0007] In the present invention, polyhedral oligomeric silsesquioxane and fluorinated alkylaluminum are used to modify the silica gel carrier. Among them, polyhedral oligomeric silsesquioxane can not only bind to the hydroxyl groups on the silica gel through alkoxy or silyl bonds, 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 carrier, but also make the distance between the F-modified sites and the metal active centers 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 "fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel" modified carrier is used to load the metallocene compound, significantly improving the catalytic activity.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] On the one hand, the present invention provides a preparation method of a supported metallocene catalyst, including the following steps:

[0010] Thermal activation treatment of the silica gel carrier:

[0011] Under vacuum conditions, the silica gel carrier is heated for thermal activation treatment;

[0012] Preparation of polyhedral oligomeric silsesquioxane / silica gel carrier:

[0013] Under a protective gas atmosphere, the thermally activated silica gel carrier is dispersed in a first solvent to form a suspension; a polyhedral oligomeric silsesquioxane solution is slowly added thereto for a first reaction. After the reaction is completed, the solvent is removed, and then it is washed and dried to obtain a silica gel carrier treated with polyhedral oligomeric silsesquioxane, that is, the polyhedral oligomeric silsesquioxane / silica gel carrier;

[0014] Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel carrier:

[0015] Under a protective gas atmosphere, the polyhedral oligomeric silsesquioxane / silica gel carrier is dispersed in a second solvent to form a suspension; a fluorinated alkylaluminum solution is slowly added thereto for a second reaction. After the reaction is completed, the solvent is removed, and then it is washed and dried to obtain the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel carrier;

[0016] Supported metallocene catalyst:

[0017] Under a protective gas atmosphere, the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel carrier is added to a third solvent to form a slurry, and a metallocene compound solution is dropped into the slurry for a third reaction to obtain the supported metallocene catalyst.

[0018] The slurry of the obtained supported metallocene catalyst can be directly used for the subsequent polymerization reaction, or the slurry of the obtained supported metallocene catalyst can be removed of the solvent, washed and dried to obtain a solid supported metallocene catalyst. Therefore, optionally, in the preparation process of the supported metallocene catalyst, it further includes: removing the solvent, washing and drying the slurry of the obtained supported metallocene catalyst to obtain a solid supported metallocene catalyst.

[0019] According to the preparation method of the present invention, preferably, in each step, based on per gram of the carrier, the addition amount of the polyhedral oligomeric silsesquioxane is 0.01 - 1 mmol, the addition amount of the fluoroalkylaluminum is 0.1 - 10 mmol, and the addition amount of the metallocene compound is 10 - 500 μmol.

[0020] According to the preparation method of the present invention, preferably, the fluoroalkylaluminum has the general formula of formula (1):

[0021] F n Al(R”) 3-n Formula (1)

[0022] In formula (1), R” represents a hydrocarbon group of C 1 -C 20 , and 1 ≤ n ≤ 3.

[0023] According to the preparation method of the present invention, preferably, the fluoroalkylaluminum is selected from at least one of diethylaluminum fluoride, difluoroethylaluminum, dipropylaluminum fluoride, difluoroethylaluminum, diisopropylaluminum fluoride, ethylpropylaluminum fluoride, and aluminum trifluoride.

[0024] According to the preparation method of the present invention, preferably, the metallocene compound has the general formula of formula (2):

[0025] Cp' 2 (Z)MX n Formula (2)

[0026] In formula (2), Cp' is a substituted or unsubstituted cyclopentadienyl, indenyl, or fluorenyl group, and the substituents are selected from C 1 -C 20 alkyl, alkoxy, silyl, aralkyloxy, or halogen;

[0027] Z is a linking unit connecting two metallocene rings. When the metallocene compound is a non-bridged metallocene complex, Z does not represent any element; when the metallocene compound is a bridged metallocene complex, 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;

[0028] M is a transition metal of Group IVB or VB;

[0029] X is the same or different and is selected from one of halogen, hydrocarbon group, hydrocarbon oxy group, acid radical, amino group; n is an integer satisfying the valence state of M;

[0030] According to the preparation method of the present invention, preferably, in the formula (2), M is zirconium or hafnium.

[0031] According to the preparation method of the present invention, preferably, in the formula (2), X is selected from halogen, alkyl, allyl, cyclopentadienyl, alkoxy, arene oxy; more preferably chlorine, bromine, methyl, ethyl, methoxy or isopropoxy; further preferably, n = 2.

[0032] According to the preparation method of the present invention, preferably, the metallocene compound is selected from bis-(n-butylcyclopentadienyl)zirconium dichloride ((n-BuCp) 2 ZrCl 2 ), bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride ((1,3-BuMeCp) 2 ZrCl 2 ), bis(1,3-butylmethylcyclopentadienyl)hafnium dichloride ((1,3-BuMeCp) 2 HfCl 2 ), ethylene bis(1-indenyl)zirconium dichloride (CH 2 (Ind) 2 ZrCl 2 ) and the like.

[0033] According to the preparation method of the present invention, preferably, in the obtained supported metallocene catalyst, the aluminum content is 1 wt% to 30 wt%; and / or

[0034] the content of the central metal (i.e., the metal in the metallocene compound) is 0.01 wt% to 5 wt%.

[0035] According to the preparation method of the present invention, preferably, in the obtained supported metallocene catalyst, the aluminum content is 5 wt% to 15 wt%; and / or

[0036] the content of the central metal (i.e., the metal in the metallocene compound) is 0.1 wt% to 1 wt%.

[0037] The reaction conditions for each preparation step are described below:

[0038] I. Thermal activation treatment of silica gel support:

[0039] Under vacuum conditions, the silica gel support is heated for thermal activation treatment.

[0040] During the thermal activation treatment of the silica gel support:

[0041] Preferably, the temperature of the thermal activation is 200 - 600 °C, and the time of the thermal activation is 1 - 24 hours. More preferably, the temperature of the thermal activation is 400 - 500 °C, and the time of the thermal activation is 6 - 10 hours.

[0042] More preferably, during the thermal activation process, the temperature is raised to the temperature of the thermal activation at a heating rate of 10 °C / min, and then the temperature is maintained for 1 - 24 hours.

[0043] II. Preparation of polyhedral oligomeric silsesquioxane / silica gel support:

[0044] Under a protective gas atmosphere, the thermally activated silica gel support is dispersed in a first solvent to form a suspension; a polyhedral oligomeric silsesquioxane solution is slowly added thereto for a first reaction. After the reaction is completed, the solvent is removed, and then it is washed and dried to obtain a silica gel support treated with polyhedral oligomeric silsesquioxane, that is, the polyhedral oligomeric silsesquioxane / silica gel support.

[0045] During the preparation of the polyhedral oligomeric silsesquioxane / silica gel support:

[0046] According to the preparation method of the present invention, preferably, based on each gram of the silica gel support, the addition amount of the polyhedral oligomeric silsesquioxane is 0.01 - 1 mmol.

[0047] Preferably, the protective gas is selected from nitrogen or inert gases, and the inert gases such as helium, argon, etc.; more preferably nitrogen.

[0048] Preferably, the temperature of the first reaction is 0 - 90 °C, and the time of the first reaction is 1 - 24 hours. More preferably, the temperature of the first reaction is 30 - 60 °C, and the time of the first reaction is 2 - 4 hours.

[0049] Preferably, the first solvent, the solvent in the polyhedral oligomeric silsesquioxane solution, and the solvent used for washing are independently selected from at least one of toluene, benzene, xylene, hexane, heptane, and cyclohexane. More preferably, the first solvent, the solvent in the polyhedral oligomeric silsesquioxane solution, and the solvent used for washing are the same, and are all toluene and / or hexane.

[0050] III. Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support:

[0051] Under a protective gas atmosphere, disperse the polyhedral oligomeric silsesquioxane / silica gel support in a second solvent to form a suspension; slowly add an aluminum alkyl fluoride solution thereto for a second reaction. After the reaction is completed, remove the solvent, and then wash and dry to obtain the aluminum alkyl fluoride / polyhedral oligomeric silsesquioxane / silica gel support.

[0052] In the preparation process of the aluminum alkyl fluoride / polyhedral oligomeric silsesquioxane / silica gel support:

[0053] Preferably, based on each gram of the polyhedral oligomeric silsesquioxane / silica gel support, the addition amount of the aluminum alkyl fluoride is 0.1 - 10 mmol.

[0054] Preferably, the protective gas is selected from nitrogen or inert gases, such as helium, argon, etc.; more preferably nitrogen.

[0055] Preferably, the temperature of the second reaction is 0 - 90 °C, and the time of the second reaction is 1 - 24 hours. More preferably, the temperature of the second reaction is 30 - 60 °C, and the time of the second reaction is 2 - 4 hours.

[0056] Preferably, the second solvent, the solvent in the aluminum alkyl fluoride solution, and the solvent used for washing are independently selected from at least one of toluene, benzene, xylene, hexane, heptane, and cyclohexane. More preferably, the second solvent, the solvent in the aluminum alkyl fluoride solution, and the solvent used for washing are the same, and are both toluene and / or hexane.

[0057] IV. Loading metallocene catalyst:

[0058] Under a protective gas atmosphere, add the aluminum alkyl fluoride / polyhedral oligomeric silsesquioxane / silica gel support to a third solvent to make a slurry, and drop a metallocene compound solution into the slurry for a third reaction to obtain a slurry of the supported metallocene catalyst.

[0059] The obtained slurry of the supported metallocene catalyst can be directly used for subsequent polymerization reactions, or the obtained slurry of the supported metallocene catalyst can be removed of the solvent, washed, and dried to obtain a solid supported metallocene catalyst. Therefore, optionally, in the preparation process of the supported metallocene catalyst, it further includes: removing the solvent, washing, and drying the obtained slurry of the supported metallocene catalyst to obtain a solid supported metallocene catalyst.

[0060] In the preparation process of the supported metallocene catalyst:

[0061] Preferably, based on each gram of the aluminum alkyl fluoride / polyhedral oligomeric silsesquioxane / silica gel support, the addition amount of the metallocene compound is 10 - 500 μmol.

[0062] Preferably, the protective gas is selected from nitrogen or an inert gas, such as helium, argon, etc.; more preferably, nitrogen.

[0063] Preferably, the temperature of the third reaction is 0-90°C, and the time of the third reaction is 0.5-12 hours. More preferably, the temperature of the third reaction is 20-40°C, and the time of the third reaction is 1-2 hours.

[0064] Preferably, the third solvent, the solvent in the metallocene compound solution, and the solvent used for washing are independently selected from at least one of toluene, benzene, xylene, hexane, heptane, and cyclohexane. More preferably, the third solvent, the solvent in the metallocene compound solution, and the solvent used for washing are the same, and are all toluene and / or hexane.

[0065] In the above steps of the preparation method of the present invention, preferably, the drying is performed by vacuum drying. In addition, the drying means commonly used in the art may also be used, which is not limited by the present invention.

[0066] In the above steps of the preparation method of the present invention, when removing the solvent after the reaction is completed, it is preferred to carry out sedimentation, and then filter out the upper clear liquid; in addition, other separation means such as centrifugation can also be used; the present invention does not limit this.

[0067] Another aspect of the present invention provides a supported metallocene catalyst obtained by any one of the above preparation methods.

[0068] The supported metallocene catalyst prepared by the present invention can be used in different polymerization methods, such as gas phase polymerization and slurry polymerization, etc.; it can be used for homopolymerization or copolymerization of olefins, and is particularly suitable for homopolymerization of ethylene or copolymerization of ethylene and other α-olefins, wherein the α-olefin can be at least one of propylene, butene, pentene, hexene, octene, 4-methylpentene-1, etc.

[0069] In another aspect, the present invention provides an application of a supported metallocene catalyst obtained by any one of the above preparation methods in an olefin polymerization reaction.

[0070] In the application, preferably, the olefin polymerization reaction is ethylene homopolymerization or copolymerization of ethylene and other α-olefins, wherein the α-olefin is selected from at least one of propylene, butene, pentene, hexene, octene and 4-methylpentene-1.

[0071] In the application, preferably, the olefin polymerization reaction is carried out in a solvent, and the solvent is selected from at least one of alkanes, aromatic hydrocarbons or halogenated hydrocarbons; more preferably at least one of hexane, pentane, heptane, benzene, toluene, dichloromethane, chloroform, and dichloroethane; further preferably at least one of hexane, toluene, and heptane.

[0072] In the said application, preferably, the usage concentration of the supported metallocene catalyst in the olefin polymerization reaction is 1×10 -8 mol / L to 1×10 -3 mol / L, and more preferably 1×10 -8 mol / L to 1×10 -5 mol / L.

[0073] In the said application, preferably, the temperature of the olefin polymerization reaction is -78°C to 100°C, and more preferably 0°C to 90°C.

[0074] In the said application, preferably, the polymerization pressure of the olefin polymerization reaction is 0.01 to 10.0 MPa, and more preferably 0.01 to 2.0 MPa.

[0075] The beneficial effects of the present invention include:

[0076] 1) The supported metallocene catalyst prepared by the present invention has good particle morphology, and the particle size can be adjusted.

[0077] 2) The supported metallocene catalyst prepared by the present invention has very high ethylene polymerization catalytic activity.

[0078] 3) The supported metallocene catalyst prepared by the present invention has good catalytic performance in the copolymerization reaction of ethylene and higher α-olefins, and has high copolymerization activity.

[0079] 4) The supported metallocene catalyst of the present invention does not use MAO either in the preparation process or in the polymerization process, greatly reducing the production cost.

[0080] 5) The resin powder obtained by using the supported metallocene catalyst prepared by the present invention for olefin polymerization has good particle morphology and high bulk density, and can be applied to slurry polymerization process and gas phase polymerization process. Detailed implementation manners

[0081] In order to illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0082] All numerical designations in the present invention (such as temperature, time, concentration, weight, etc., including the range of each of them) can generally be approximate values that can be appropriately changed (+) or (-) in increments of 0.1 or 1.0. All numerical designations can be understood as being preceded by the term "about".

[0083] The test methods involved in the following examples include:

[0084] 1) ICP (Inductively Coupled Plasma) Characterization:

[0085] Quantitatively determine the weight percentage of metals in the supported metallocene catalyst. The instrument selected is a P1000 type ICP-AES inductively coupled plasma emission spectrometer.

[0086] 2) Characterization of Polymer Molecular Weight and Molecular Weight Distribution:

[0087] The molecular weight and its distribution are determined by gel permeation chromatography (GPC). The instrument used is an 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.

[0088] Example 1

[0089] This example prepares a supported metallocene catalyst A, including the following steps:

[0090] (1) Thermal activation treatment of silica gel support

[0091] Heat the 955 silica gel support 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 support.

[0092] (2) Preparation of polyhedral oligomeric silsesquioxane / silica gel support

[0093] Under nitrogen protection, take 2.0 grams of the above-mentioned thermally activated silica gel support and add it to a glass reactor. Add 80 milliliters of dried toluene to disperse it into a suspension. Add 0.5 milliliter of a 1 mmol / mL polyhedral oligomeric silsesquioxane toluene solution, raise the temperature to 90 °C, and stir and react for 1 hour; after sedimentation, filter out the upper clear liquid by pressure filtration, then wash it three times with 60 milliliters of toluene, then wash it once with 60 milliliters of hexane, and dry it under vacuum to obtain a solid powder with good fluidity, namely polyhedral oligomeric silsesquioxane / silica gel support.

[0094] (3) Preparation of fluorinated alkyl aluminum / polyhedral oligomeric silsesquioxane / silica gel support

[0095] Under nitrogen protection, take 2.0 grams of the above-mentioned polyhedral oligomeric silsesquioxane / silica gel support and add it to a glass reactor. Add 80 milliliters of dried toluene to disperse it into a suspension. Add 0.5 milliliter of a 10 mmol / mL difluoroethyl aluminum toluene solution, raise the temperature to 90 °C, and stir and react for 1 hour; after sedimentation, filter out the upper clear liquid by pressure filtration, then wash it three times with 60 milliliters of toluene, then wash it once with 60 milliliters of hexane, and dry it under vacuum to obtain a solid powder with good fluidity, namely fluorinated alkyl aluminum / polyhedral oligomeric silsesquioxane / silica gel support.

[0096] (4) Supported metallocene catalyst

[0097] Under nitrogen protection, 1 g of the previously obtained fluorinated alkylaluminum / poly(silsesquioxane) / silica gel support was added to a glass reactor, and 20 mL of dried toluene was added to make a slurry. A solution of 40.4 mg of bis-(n-butylcyclopentadienyl)zirconium dichloride (n-BuCp) 2 ZrCl 2 dissolved in 10 mL of toluene was dropped into 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 the supported metallocene catalyst A.

[0098] Characterized by ICP, in catalyst A, the weight content of Zr is 0.56%, the weight content of Al is 5.89%, and the weight content of F is 13.56%.

[0099] Example 2

[0100] This example prepares a supported metallocene catalyst B, which includes the following steps:

[0101] (1) Thermal activation treatment of silica gel support

[0102] The 955 silica gel support 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 the thermally activated silica gel support.

[0103] (2) Preparation of poly(silsesquioxane) / silica gel support

[0104] Under nitrogen protection, 2.0 g of the above-obtained thermally activated silica gel support was added to a glass reactor, 80 mL of dried toluene was added to disperse it into a suspension, 0.5 mL of a 1 mmol / mL poly(silsesquioxane) toluene solution was added, the temperature was raised to 40 °C, and the reaction was stirred for 2 hours; after sedimentation, the upper clear liquid was taken out by pressure filtration, then washed three times with 60 mL of toluene and once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, that is, the poly(silsesquioxane)-treated silica gel support.

[0105] (3) Preparation of fluorinated alkylaluminum / poly(silsesquioxane) / silica gel support

[0106] Under nitrogen protection, 2.0 g of the obtained polyhedral oligomeric silsesquioxane / silica gel support was added to a glass reactor, 80 mL of dried toluene was added, and it was dispersed into a suspension. 0.5 mL of a 10 mmol / mL toluene solution of diethylaluminum fluoride was added, and the temperature was raised to 40 °C, followed by stirring for 2 hours; after sedimentation, the upper clear liquid was taken out by pressure filtration, then washed three times with 60 mL of toluene and once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely alkylaluminum fluoride / polyhedral oligomeric silsesquioxane / silica gel support.

[0107] (4) Supported metallocene catalyst

[0108] Under nitrogen protection, 1 g of the previously obtained alkylaluminum fluoride / polyhedral oligomeric silsesquioxane / silica gel support 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 the supported metallocene catalyst B.

[0109] Characterized by ICP, in catalyst B, the Zr weight content is 0.33%, the Al weight content is 14.71%, and the F weight content is 10.71%.

[0110] Example 3

[0111] This example prepares a supported metallocene catalyst C, which includes the following steps:

[0112] (1) Thermal activation treatment of silica gel support

[0113] The 955 silica gel support was heated under a vacuum state, heated from 20 °C to 600 °C at a heating rate of 10 °C / min. After reaching 600 °C, it was maintained for 1 hour to obtain the thermally activated silica gel support.

[0114] (2) Preparation of polyhedral oligomeric silsesquioxane / silica gel support

[0115] Under nitrogen protection, 2.0 g of the obtained thermally activated silica gel support was added to a glass reactor, 80 mL of dried toluene was added, and it was dispersed into a suspension. 1 mL of a 0.1 mmol / mL toluene solution of polyhedral oligomeric silsesquioxane was added, and the temperature was lowered to 0 °C, followed by stirring for 24 hours; after sedimentation, the upper clear liquid was taken out by pressure filtration, then washed three times with 60 mL of toluene and once with 60 mL of hexane, and dried under vacuum to obtain a solid powder with good fluidity, namely polyhedral oligomeric silsesquioxane / silica gel support.

[0116] (3) Preparation of Fluoroalkylaluminum / Poly(silsesquioxane) / Silica Gel Support

[0117] Under nitrogen protection, 2.0 g of the obtained poly(silsesquioxane) / silica gel support was added to a glass reactor, 80 mL of dried toluene was added, and it was dispersed into a suspension. 1 mL of a 1 mmol / mL toluene solution of dipropylaluminum fluoride was added, and the temperature was lowered to 0 °C, followed by stirring for 24 hours; after sedimentation, the upper clear liquid was taken out by pressure filtration, then 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 fluoroalkylaluminum / poly(silsesquioxane) / silica gel support.

[0118] (4) Supported Metallocene Catalyst

[0119] Under nitrogen protection, 1 g of the previously obtained fluoroalkylaluminum / poly(silsesquioxane) / silica gel support was added to a glass reactor, and 20 mL of dried toluene was added to make a slurry. 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 washed with 20 mL of toluene and dried under vacuum to obtain the supported metallocene catalyst C.

[0120] Characterized by ICP, in catalyst C, the weight content of Hf is 0.13%, the weight content of A1 is 1.58%, and the weight content of F is 3.11%.

[0121] Example 4

[0122] This example prepares a supported metallocene catalyst D, including the following steps:

[0123] (1) Thermal Activation Treatment of Silica Gel Support

[0124] The 955 silica gel support 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 the thermally activated silica gel support.

[0125] (2) Preparation of Poly(silsesquioxane) / Silica Gel Support

[0126] Under nitrogen protection, 2.0 g of the obtained polyhedral oligomeric silsesquioxane / silica gel support 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; after sedimentation, the upper clear liquid was taken out by pressure filtration, then washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried in vacuo to obtain a solid powder with good fluidity, namely polyhedral oligomeric silsesquioxane / silica gel support.

[0127] (3) Preparation of fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support

[0128] Under nitrogen protection, 2.0 g of the obtained polyhedral oligomeric silsesquioxane / silica gel support 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; after sedimentation, the upper clear liquid was taken out by pressure filtration, then washed three times with 60 mL of toluene, then washed once with 60 mL of hexane, and dried in vacuo to obtain a solid powder with good fluidity, namely fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support.

[0129] (4) Loading metallocene catalyst

[0130] Under nitrogen protection, 1 g of the previously obtained fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel support 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, reacted at 40 °C for 2 hours, then washed with 20 mL of toluene, and dried in vacuo to obtain the supported metallocene catalyst D.

[0131] Characterized by ICP, in catalyst D, the Zr weight content is 0.91%, the Al weight content is 20.13%, and the F weight content is 17.62%.

[0132] Example 5

[0133] This example prepares a supported metallocene catalyst E, which includes the following steps:

[0134] (1) Thermal activation treatment of silica gel support

[0135] Same as step (1) in Example 2.

[0136] (2) Preparation of polyhedral oligomeric silsesquioxane / silica gel support

[0137] Same as step (2) in Example 2.

[0138] (3) Preparation of Fluoroalkylaluminum / Polysilsesquioxane / Silica Gel Support

[0139] Same as step (3) in Example 2.

[0140] (4) Supported Metallocene Catalyst

[0141] Same as step (4) in Example 2, except that 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 is changed to 4.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 , to obtain supported metallocene catalyst E.

[0142] Characterized by ICP, in catalyst E, the weight content of Zr is 0.04%, the weight content of Al is 12.14%, and the weight content of F is 8.27%.

[0143] Example 6

[0144] This example prepares a supported metallocene catalyst F, including the following steps:

[0145] (1) Thermal Activation Treatment of Silica Gel Support

[0146] Same as step (1) in Example 2.

[0147] (2) Preparation of Polysilsesquioxane / Silica Gel Support

[0148] Same as step (2) in Example 2.

[0149] (3) Preparation of Fluoroalkylaluminum / Polysilsesquioxane / Silica Gel Support

[0150] Same as step (3) in Example 2.

[0151] (4) Supported Metallocene Catalyst

[0152] Same as step (4) in Example 2, except that 43.3 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 is changed to 216.5 mg of bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride (1,3-BuMeCp) 2 ZrCl 2 , to obtain supported metallocene catalyst F.

[0153] Characterized by ICP, in catalyst F, the weight content of Zr is 4.92%, the weight content of Al is 9.87%, and the weight content of F is 7.14%.

[0154] Comparative Example 1

[0155] This comparative example prepares a supported metallocene catalyst G, including the following steps:

[0156] (1) Thermal activation treatment of silica gel support

[0157] Same as step (1) in Example 2.

[0158] (2) Preparation of polyhedral oligomeric silsesquioxane / silica gel support

[0159] Same as step (2) in Example 2.

[0160] (3) Supporting metallocene catalyst

[0161] Under nitrogen protection, add 1 g of the obtained polyhedral oligomeric silsesquioxane / silica gel support to a glass reactor, add 20 mL of dried toluene to make a slurry, and 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 to the reactor, react at 25 °C for 1 hour, then wash with 20 mL of toluene and dry under vacuum to obtain the supported metallocene catalyst G.

[0162] Characterized by ICP, in catalyst G, the weight content of Zr is 0.24%.

[0163] Comparative Example 2

[0164] This comparative example prepares a supported metallocene catalyst H, including the following steps:

[0165] (1) Thermal activation treatment of silica gel support

[0166] Same as step (1) in Comparative Example 1.

[0167] (2) Preparation of fluorinated alkylaluminum / silica gel support

[0168] Under nitrogen protection, take 2.0 g of the obtained thermally activated silica gel support and add it to a glass reactor, add 80 mL of dried toluene, disperse it into a suspension, add 0.5 mL of 10 mmol / mL toluene solution of diethylaluminum fluoride, heat up to 40 °C, stir and react for 2 hours, wash three times with 60 mL of toluene and once with 60 mL of hexane, and dry under vacuum to obtain a solid powder with good fluidity, namely fluorinated alkylaluminum / silica gel support.

[0169] (3) Supported metallocene catalyst

[0170] Under nitrogen protection, 1 g of the previously obtained fluorinated alkylaluminum / silica support was added to a glass reactor, and 20 mL of dried toluene was added to make 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 under vacuum to obtain the supported metallocene catalyst H.

[0171] Characterized by ICP, in catalyst H, the Zr weight content is 0.27%, the Al weight content is 8.42%, and the F weight content is 6.54%.

[0172] Comparative Example 3

[0173] This comparative example prepared an unsupported metallocene catalyst I, including the following steps:

[0174] Take 0.5 mL of a 10 mmol / mL toluene solution of diethylaluminum fluoride and mix it with 0.5 mL of a 1 mmol / mL toluene solution of poly(silsesquioxane). Heat up to 40 °C and stir for 2 h. 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 to obtain the unsupported metallocene catalyst I.

[0175] Use the unsupported metallocene catalyst I to catalyze ethylene polymerization, and the results are shown in Table 1.

[0176] Comparative Example 4

[0177] This comparative example prepared a supported metallocene catalyst I, including the following steps:

[0178] Prepare the supported metallocene catalyst J according to Example 2 in the application document of CN115651101A.

[0179] Characterized by ICP, in catalyst J, the Zr weight content is 0.40%, the Al weight content is 6.86%, and the F weight content is 4.17%.

[0180] Application Examples 1-7 and Comparative Application Examples 1-4

[0181] High-pressure ethylene polymerization experiment

[0182] In a 1-liter stainless steel high-pressure polymerization autoclave, nitrogen and ethylene were each replaced three times, and then 2 liters of hexane solvent was added. With the addition of hexane, 4 ml of a 1 mol / L triethylaluminum (TEA) hexane solution and the required amount of 1-hexene were added. Then, 15 mg of the metallocene catalyst prepared in the above examples and comparative examples was added. The temperature was raised to 85 °C, the pressure was raised to and maintained at 1.0 MPa, and the reaction was carried out for 2 hours. After the polymerization reaction was completed, the temperature was lowered, and the polyethylene particle powder was collected and weighed.

[0183] The specific polymerization results are listed in Table 1.

[0184] Table 1 Polymerization Results of Metallocene Catalysts

[0185]

[0186] As can be seen from Table 1, after the catalyst support was successively treated with polyhedral oligomeric silsesquioxane and modified with fluorinated alkylaluminum, the metallocene supported on the "fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel" support achieved a significant improvement in catalytic activity. Compared with the support without fluorinated alkylaluminum modification, the polymerization activity after loading the metallocene catalyst increased by 3 to 9 times. Compared with the support without polyhedral oligomeric silsesquioxane treatment, the polymerization activity after loading the metallocene catalyst increased by 50% to 120%.

[0187] At the same time, the addition of polyhedral oligomeric silsesquioxane increased the content and stability of F element, and thus increased the activity. Compared with the support treated by multiple steps of "alkylaluminum + thermal calcination in nitrogen atmosphere + thermal calcination in oxygen atmosphere + thermal calcination with addition of fluorination reagent", the use of the fluorinated alkylaluminum / polyhedral oligomeric silsesquioxane / silica gel modified support could increase the catalyst activity by more than 70% to 150%.

[0188] Obviously, the above examples of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A preparation method of a supported metallocene catalyst, wherein, the preparation method comprises the following steps: Thermal activation treatment of the silica support: Under vacuum conditions, heat the silica support for thermal activation treatment; Preparation of poly(silsesquioxane) / silica support: Under a protective gas atmosphere, disperse the thermally activated silica support in a first solvent to form a suspension; slowly add a poly(silsesquioxane) solution thereto for a first reaction, remove the solvent after the reaction ends, and then wash and dry to obtain a poly(silsesquioxane)-treated silica support, i.e., the poly(silsesquioxane) / silica support; Preparation of fluoroalkylaluminum / poly(silsesquioxane) / silica support: Under a protective gas atmosphere, disperse the poly(silsesquioxane) / silica support in a second solvent to form a suspension; slowly add a fluoroalkylaluminum solution thereto for a second reaction, remove the solvent after the reaction ends, and then wash and dry to obtain the fluoroalkylaluminum / poly(silsesquioxane) / silica support; Supported metallocene catalyst: Under a protective gas atmosphere, add the fluoroalkylaluminum / poly(silsesquioxane) / silica support to a third solvent to form a slurry, and dropwise add a metallocene compound solution to the slurry for a third reaction to obtain a slurry of the supported metallocene catalyst.

2. The preparation method according to claim 1, wherein, the process of supporting the metallocene catalyst further comprises: removing the solvent, washing, and drying the obtained slurry of the supported metallocene catalyst to obtain a solid supported metallocene catalyst.

3. The preparation method according to claim 1, wherein, in each step, based on per gram of the support, the addition amount of the poly(silsesquioxane) is 0.01 - 1 mmol, the addition amount of the fluoroalkylaluminum is 0.1 - 10 mmol, and the addition amount of the metallocene compound is 10 - 500 μmol.

4. The preparation method according to claim 1, wherein, the general formula of the fluoroalkylaluminum is formula (1): F n Al(R”) 3-n Formula (1) In formula (1), R” represents a hydrocarbon group of C 1 -C 20 where 1 ≤ n ≤ 3.

5. The preparation method according to claim 1, wherein, the fluoroalkylaluminum is selected from at least one of diethylaluminum fluoride, difluoroethylaluminum, dipropylaluminum fluoride, difluoroethylaluminum, diisopropylaluminum fluoride, ethylpropylaluminum fluoride, and aluminum trifluoride.

6. The preparation method according to claim 1, wherein, the general formula of the metallocene compound is formula (2): Cp' 2 (Z)MX n Formula (2) In formula (2), Cp' is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group, and the substituent is selected from C 1 -C 20 alkyl, alkoxy, silyl, aralkyloxy or halogen; Z is a linking unit connecting two metallocene rings. When the metallocene compound is a non-bridged metallocene complex, Z does not represent any element; When the metallocene compound is a bridged metallocene complex, Z is selected from SiR' 2 , CR' 2 , SiR' 2 SiR' 2 , CR' 2 CR' 2 , CR'=CR' or CR' 2 SiR' 2 , wherein 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 IVB or VB; X is the same or different and is selected from one of halogen, hydrocarbon group, alkoxy group, acid radical, and amino group; n is an integer satisfying the valence state of M.

7. The preparation method according to claim 6, wherein, in formula (2), M is zirconium or hafnium.

8. The preparation method according to claim 6, wherein, in formula (2), X is selected from halogen, alkyl, allyl, cyclopentadienyl, alkoxy, and aryloxy.

9. The preparation method according to claim 6, wherein, The metallocene compound is selected from at least one of bis-(n-butylcyclopentadienyl)zirconium dichloride, bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride, bis(1,3-butylmethylcyclopentadienyl)hafnium dichloride, and ethylene bis(1-indenyl)zirconium dichloride.

10. According to the preparation method described in claim 1, wherein, in the obtained supported metallocene catalyst, the aluminum content is 1 wt% to 30 wt%; and / or the content of the central metal is 0.01 wt% to 5 wt%, and the central metal is the metal in the metallocene catalyst.

11. According to the preparation method described in claim 1, wherein, the temperature of the thermal activation is 200 to 600 °C, and the time of the thermal activation is 1 to 24 hours.

12. According to the preparation method described in claim 1, wherein, the temperature of the first reaction is 0 to 90 °C, and the time of the first reaction is 1 to 24 hours.

13. According to the preparation method described in claim 1, wherein, the temperature of the second reaction is 0 to 90 °C, and the time of the second reaction is 1 to 24 hours.

14. According to the preparation method described in claim 1, wherein, the temperature of the third reaction is 0 to 90 °C, and the time of the third reaction is 0.5 to 12 hours.

15. According to the preparation method described in claim 1, wherein, the first solvent, the second solvent, the third solvent, the solvent in the polyhedral oligomeric silsesquioxane solution, the solvent in the fluorinated alkylaluminum solution, the solvent in the metallocene compound solution, and the solvent used for washing are independently selected from at least one of toluene, benzene, xylene, hexane, heptane, and cyclohexane.

16. A supported metallocene catalyst obtained by the preparation method according to any one of claims 1-15.

17. An application of the supported metallocene catalyst according to claim 16 in an olefin polymerization reaction.

18. According to the application described in claim 17, wherein, the olefin polymerization reaction is a homopolymerization reaction of ethylene or a copolymerization reaction of ethylene and other α-olefins, and the α-olefins are selected from at least one of propylene, butene, pentene, hexene, octene, and 4-methylpentene-1.

19. According to the application described in claim 17, wherein, the olefin polymerization reaction is carried out in a solvent, and the solvent is selected from at least one of alkanes, aromatic hydrocarbons, and halogenated hydrocarbons.

20. According to the application described in claim 17, wherein, The usage concentration of the supported metallocene catalyst in the olefin polymerization reaction is 1×10 -8 mol / L to 1×10 -3 mol / L.

21. According to the application described in claim 17, wherein, the temperature of the olefin polymerization reaction is -78 °C to 100 °C, and the polymerization pressure is 0.01 to 10.0 MPa.

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