Supported metallocene catalyst and preparation method and application thereof

Abstract

The invention discloses a supported metallocene catalyst as well as a preparation method and application thereof. The catalyst comprises a metallocene compound, a cocatalyst and a carrier, the carrier is mesoporous silica with dual pore size distribution, the metallocene compound has a structure as shown in (I), L1 and L2 are respectively and independently cyclopentadienyl and fluorenyl, and L1 and L2 are the same or different; r1 and R2 are respectively substituent groups on L1 and L2, and R1 and R2 are respectively and independently C1-C6 alkyl groups or aryl groups; p and q are the numbers of R1 and R2 respectively, and are 0, 1, 2 or 3 respectively; z is-C (CH3) 2-or-CPh2-, wherein Ph is phenyl; m is Ti, Zr or Hf; and X is halogen and C1-C4 alkyl. The catalyst has high catalytic activity and can be used for catalyzing ethylene polymerization to obtain ultra-high molecular weight polyethylene.

Description

A supported metallocene catalyst, its preparation method and application Technical Field

[0001] This invention relates to the field of olefin polymerization, and more specifically, to a supported metallocene catalyst and its preparation method, as well as the application of the catalyst in the preparation of ultra-high molecular weight polyethylene. Background Technology

[0002] Ultra-high molecular weight polyethylene refers to polyethylene with a viscosity-average molecular weight greater than 1×10⁻⁶. 6 Polyethylene with a g / mol content has excellent wear resistance and impact strength, and therefore has been widely used in industrial and medical fields, such as cables, pipes, artificial joints, battery separators, helmets, and bulletproof vests.

[0003] Currently, most industrially produced ultra-high molecular weight polyethylene is produced using Ziegler-Natta catalysts. Ziegler-Natta catalysts are multi-active-center catalysts, which produce polymers with a wide molecular weight distribution and a high degree of polymer chain entanglement. This has an adverse effect on the processing performance of the polymer and the mechanical and wear-resistant properties of the final product.

[0004] Currently, there are also studies using single-center catalysts such as non-metallocene catalysts to prepare ultra-high molecular weight polyethylene. For example, CN101205235A discloses a method for preparing ultra-high molecular weight polyethylene using a non-metallocene catalyst. The ultra-high molecular weight polyethylene obtained has a narrow molecular weight distribution and uniform particle size, which is beneficial for processing.

[0005] Mesoporous materials possess high specific surface area, regular pore structure, and specific pore size distribution, making them widely used in catalysis. In olefin polymerization, the pore size of the support significantly affects the catalytic performance of the catalyst. However, existing mesoporous material supports exhibit poor pore wall stability, impacting the morphology and polymerization activity of the supported catalyst.

[0006] Therefore, finding a mesoporous material with a stable mesoporous structure that can maintain an ordered mesoporous structure and have high catalytic activity after loading active components remains an urgent technical problem to be solved. Summary of the Invention

[0007] Existing technologies have disclosed some methods for preparing ultra-high molecular weight polyethylene using metallocene catalysts, but the polymerization activity is generally low, making it difficult to obtain polymers with higher molecular weights, and thus cannot meet the requirements of actual production.

[0008] To address the problems existing in the prior art, the present invention provides a supported metallocene catalyst and its preparation method.

[0009] One objective of this invention is to provide a supported metallocene catalyst that catalyzes ethylene polymerization and can produce ultra-high molecular weight polyethylene at a high polymerization activity.

[0010] The supported metallocene catalyst for preparing ultra-high molecular weight polyethylene of the present invention comprises the following components:

[0011] Metallocene compounds;

[0012] Co-catalyst;

[0013] Carrier.

[0014] The metallocene compounds of the present invention have the structure shown in (I):

[0015]

[0016] in,

[0017] L 1 L 2 Each is independently cyclopentadienyl and fluorenyl, L 1 L 2 They can be the same or different;

[0018] R 1 R 2 For L 1 L 2 The substituents on it are each independently a C1 to C6 alkyl or aryl group, R 1 R 2 They can be the same or different;

[0019] p and q are R 1 R 2 The quantity can be 0, 1, 2 or 3 respectively;

[0020] Z is -C(CH3)2- or -CPh2-, where Ph is phenyl;

[0021] M is Ti, Zr, or Hf;

[0022] X is a halogen or a C1-C4 alkyl group.

[0023] In a preferred embodiment of the present invention

[0024] L 1 Cyclopentadienyl, L 2 It is a fluorene base;

[0025] R 1 R 2 Each is independently a C1 to C5 alkyl or aryl group, R 1 R2 They can be the same or different; p and q are R 1 R 2 The quantity, p = 0, q is 0, 1 or 2;

[0026] Z is -C(CH3)2- or -CPh2-, where Ph is phenyl;

[0027] M is Ti, Zr, or Hf;

[0028] X represents halogen or methyl.

[0029] In a more preferred embodiment of the present invention,

[0030] R 1 R 2 Each can be an alkyl or phenyl group, either C1 to C5.

[0031] Non-limiting examples of the metallocene compounds described in this invention are:

[0032] Isopropyl-bridged (cyclopentadienyl-fluorenyl)titanium dichloride;

[0033] Isopropyl-bridged (cyclopentadienyl-fluorenyl)zirconium dichloride;

[0034] Isopropyl-bridged (cyclopentadienyl-fluorenyl) hafnium dichloride;

[0035] Isopropyl-bridged (cyclopentadienyl-fluorenyl)dimethyltitanium;

[0036] Isopropyl-bridged (cyclopentadienyl-fluorenyl)dimethylzirconium;

[0037] Isopropyl-bridged (cyclopentadienyl-fluorenyl)dimethylhafnium;

[0038] Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)titanium dichloride;

[0039] Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)zirconium dichloride;

[0040] Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl) hafnium dichloride;

[0041] Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)dimethyltitanium;

[0042] Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)dimethylzirconium;

[0043] Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)dimethylhafnium;

[0044] Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)titanium dichloride;

[0045] Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)zirconium dichloride;

[0046] Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl) hafnium dichloride;

[0047] Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethyltitanium;

[0048] Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylzirconium;

[0049] Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylhafnium;

[0050] Diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)titanium dichloride;

[0051] Diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)zirconium dichloride;

[0052] Diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl) hafnium dichloride;

[0053] Diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethyltitanium;

[0054] Diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylzirconium;

[0055] Diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylhafnium.

[0056] The preferred metallocene compounds of this invention are diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)zirconium dichloride and diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylzirconium.

[0057] The cocatalyst described in this invention refers to a substance that can react with metallocene compounds to form a transition metal cation catalytic active center, such as at least one of alkylaluminoxanes or organoboron compounds.

[0058] Common examples of alkylaluminoxanes include methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, and isobutylaluminoxane, with methylaluminoxane or modified methylaluminoxane being preferred.

[0059] Common examples of organoboron compounds include at least one of triphenylcarbazo(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetra(pentafluorophenyl)borate, and N,N-dimethylbenzylammonium tetra(pentafluorophenyl)borate.

[0060] The carrier described in this invention is a mesoporous silica carrier with a dual pore size distribution, having a specific surface area of ​​100–350 m² / g, a pore volume of 0.5–1.5 mL / g, and a bimodal pore size distribution, with the most probable pore sizes corresponding to the bimodal peaks being 1–10 nm and 20–50 nm, respectively.

[0061] In a preferred embodiment of the present invention, the carrier needs to undergo activation treatment, which is performed by dehydrating and dehydroxylating the carrier using heating, vacuuming, or other known physical or chemical methods. Preferably, heating followed by vacuuming is used.

[0062] The mesoporous silica with dual pore size distribution described in this invention can be prepared using methods in the prior art, such as the method in CN109289936A, or adjusted according to the actual requirements.

[0063] In the supported metallocene catalyst of the present invention, the content of aluminum or boron in the co-catalyst is 12-20% by weight, for example, 12% by weight, 14% by weight, 16% by weight, 18% by weight, 20% by weight, etc.; the content of M in the metallocene compound is 0.1-0.4% by weight, for example, 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, etc.

[0064] A second objective of this invention is to provide a method for preparing the aforementioned supported metallocene catalyst, comprising the following steps:

[0065] (a) Add solvent to the support, then add co-catalyst, and stir to obtain a suspension of the support loaded with co-catalyst;

[0066] (b) Add the metallocene compound slurry to the suspension, stir, and then wash and remove the solvent.

[0067] In step (a), the solvent may be selected from at least one of toluene, xylene, etc.

[0068] In step (a), the catalyst is added at 50–100°C and stirred for 1–10 hours.

[0069] In step (b), a metallocene compound slurry is added at 0–50°C and stirred for 30–180 minutes.

[0070] In step (b), the solvent for the metallocene compound slurry may be selected from at least one of toluene, xylene, etc.

[0071] The preparation method of the present invention further includes the steps of washing the obtained product with alkane, filtering, and removing solvent.

[0072] A third objective of this invention is to provide the application of the supported metallocene catalyst or the supported metallocene catalyst obtained by the preparation method in the preparation of ultra-high molecular weight polyethylene.

[0073] The supported metallocene catalyst of the present invention can be used in the field of ethylene polymerization to prepare ultra-high molecular weight polyethylene.

[0074] The supported catalyst of this invention exhibits higher polymerization activity and a higher molecular weight polymer when preparing ultra-high molecular weight polyethylene. Attached Figure Description

[0075] Figure 1 is a scanning electron microscope (SEM) image of the microstructure of mesoporous silica (S1) in the embodiment.

[0076] Figure 2 shows the particle size distribution curve of the mesoporous silica (S1) in the embodiment.

[0077] Figure 3 is a pore size distribution diagram of the mesoporous silica (S1) in the embodiment.

[0078] Figure 4 is the NMR spectrum of the metallocene compound of Example 2. Detailed Implementation

[0079] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0080] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0081] Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0082] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0083] According to a preferred embodiment of the present invention, the preparation method of the supported metallocene catalyst of the present invention includes the following steps:

[0084] (a) Toluene is added to the treated carrier and stirred to form a suspension. The suspension is heated to 50-100°C. Then, a co-catalyst solution, such as an alkylaluminoxane toluene solution, is added dropwise to the suspension. The mixture is stirred at a constant temperature for 1-10 hours. Toluene is removed by filtration. The mixture is then washed with toluene and filtered at least twice. Finally, toluene is added and stirred to obtain a suspension of the alkylaluminoxane-supported active carrier.

[0085] (b) Add toluene to the metallocene compound and stir to form a homogeneous slurry. Add the metallocene compound slurry to the carrier suspension prepared in step (a) at 0–50°C and continue stirring for 30–180 minutes. Filter to remove toluene, and then wash and filter with toluene at least twice.

[0086] (c) The product obtained in step (b) is washed with alkane and filtered at least three times to remove residual toluene from the product, thereby obtaining the supported metallocene catalyst.

[0087] All of the above steps are carried out under the protection of an inert gas.

[0088] Preparation of mesoporous silica with dual pore size distribution:

[0089] 1.0 g of hexadecyltrimethylammonium bromide (CTAB) and 3.0 ml of polyethylene glycol octylphenyl ether (Trappon-X100) were added to a hydrochloric acid solution consisting of 80 g of 37% concentrated hydrochloric acid and 180 g of water. The mixture was stirred at 40 °C until CTAB was completely dissolved. Then, 8.5 g of tetraethyl orthosilicate was added to the above solution. The mixture was stirred at 40 °C for 10 hours with a mechanical stirring rate of 340 r / min, and then allowed to stand at 60 °C for 24 hours. The resulting solution was transferred to a polytetrafluoroethylene-lined reactor and crystallized at 40 °C for 20 hours. After filtration and washing, mesoporous filter cake A1 was obtained.

[0090] A mixture of 15% by weight water glass, 12% by weight sulfuric acid solution, and glycerol in a weight ratio of 6:3:1 was reacted at 40°C for 2 hours. The pH was then adjusted to 2 with 98% by weight sulfuric acid. The resulting reaction mixture was then filtered and washed with distilled water until the sodium ion content was 0.02% by weight, yielding silica gel filter cake B1.

[0091] 10g of filter cake A1 and 20g of filter cake B1 prepared above were placed together in a 100mL ball mill jar. The ball mill jar and grinding balls were made of agate, with a diameter of 3mm and a quantity of one ball. The rotation speed was 300r / min. The ball mill jar was sealed, and the first ball milling was carried out inside the jar at a temperature of 30℃ for 5 hours. The resulting first ball mill slurry was mixed with 80g of water at 25℃ to form a pulp, and then subjected to a second ball milling at a temperature of 30℃ for 5 hours. The resulting second ball mill slurry was spray-dried at 200℃ and a rotation speed of 9000r / min, and then screened using cyclone separation technology. The screened product was calcined in a muffle furnace at 400℃ for 10 hours to remove the template agent, yielding spherical mesoporous silica S1.

[0092] The spherical mesoporous silica Si was characterized using scanning electron microscopy, laser particle size analyzer, and nitrogen adsorption analyzer.

[0093] Figure 1 is a SEM image of the microstructure of spherical mesoporous silica S1. As can be seen from the figure, the microstructure of spherical mesoporous silica S1 consists of microspheres with a particle size of 50 μm.

[0094] Figure 2 shows the particle size distribution curve of spherical mesoporous silica S1. As can be seen from the figure, spherical mesoporous silica S1 has a uniform particle size distribution.

[0095] Figure 3 is a pore size distribution diagram of spherical mesoporous silica S1. As can be seen from the figure, spherical mesoporous silica S1 has a dual-pore structure distribution and uniform pores.

[0096] The pore structure parameters of spherical microporous silica S1 are shown in Table 1 below.

[0097] Table 1

[0098]

[0099] *: The first most probable aperture and the second most probable aperture are separated by a comma: in order from left to right, they are the first most probable aperture and the second most probable aperture.

[0100] Activation treatment of the carrier:

[0101] The spherical mesoporous silica carriers used in the examples and comparative examples were heated at 600°C for 6 hours under a dry nitrogen flow, and then sealed and stored in a nitrogen chamber for later use.

[0102] The metallocene compounds used can be prepared according to the methods described in the following literature:

[0103] Syndiospecific polymerization of propylene:2-and 2,7-substitutedmetallocene complexes of type(C 13 H8-nRnCR'2C5H4)MCl2 (n=1,2; R=alkoxy, alkyl, aryl, hal; R'=Me, Ph; M=Zr, Hf), Journal of Organometallic Chemistry, 522(1), Pages: 39-54, 1996.

[0104] Example 1

[0105] Preparation of supported catalyst C1

[0106] Methylaluminoxane solution: Add 4.9 g of methylaluminoxane to a reaction flask, and add 10 mL of toluene at room temperature and stir to form a solution.

[0107] Metallocene compound slurry: Weigh 0.25 g of isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)zirconia dichloride and add it to the reaction flask, then add 10 mL of toluene and stir well.

[0108] Under nitrogen protection, 7.0 g of activated mesoporous silica support with a dual-pore size distribution (S1) was weighed and added to a reaction flask equipped with a mechanical stirrer. Then, 20 mL of toluene was added, and the mixture was stirred to form a suspension and heated to 100 °C. A methylaluminoxane solution was then added to the silica support suspension, and the mixture was stirred at a constant temperature for 3 hours. Toluene was removed by filtration, and the product was then washed twice with 20 mL of toluene at 100 °C and filtered. Another 20 mL of toluene was added to the above product, and the mixture was stirred to form a suspension and heated to 30 °C. A metallocene compound slurry was then added to the above support suspension, and the mixture was stirred at a constant temperature for 60 min. Toluene was removed by filtration, and the product was washed twice with 20 mL of toluene and filtered, followed by three washes with 20 mL of n-hexane and filtered. The n-hexane was then removed under vacuum to obtain 12.0 g of the supported metallocene catalyst. The supported catalyst contained 19 wt% aluminum and 0.3 wt% zirconium.

[0109] Example 2

[0110] Preparation of supported catalyst C2

[0111] The preparation process is the same as in Example 1, except that the metallocene compound is replaced with 0.30g of diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)zirconium dichloride.

[0112] 12.0 g of supported metallocene catalyst was prepared. The supported catalyst contained 19 wt% aluminum and 0.3 wt% zirconium.

[0113] Example 3

[0114] Preparation of supported catalyst C3

[0115] The preparation process is the same as in Example 2, except that the metallocene compound is adjusted to 0.25g and the amount of methylaluminoxane is 4.2g.

[0116] 11.1 g of supported metallocene catalyst was prepared. The supported catalyst contained 17 wt% aluminum and 0.2 wt% zirconium.

[0117] Example 4

[0118] Preparation of C4 supported catalyst

[0119] The preparation process is the same as in Example 3, except that the metallocene compound is changed to diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylzirconium.

[0120] 11.3 g of supported metallocene catalyst was prepared. The supported catalyst contained 17 wt% aluminum and 0.3 wt% zirconium.

[0121] Example 5

[0122] Preparation of supported catalyst C5

[0123] The preparation process is the same as in Example 3, except that the metallocene compound is replaced with 0.20g of diphenylmethylene-bridged (cyclopentadienyl) (fluorenyl) zirconium dichloride, and the amount of methylaluminoxane is 4.2g.

[0124] 11.2 g of supported metallocene catalyst was prepared. The supported catalyst contained 17 wt% aluminum and 0.3 wt% zirconium.

[0125] Comparative Example 1

[0126] Preparation of supported catalyst D1

[0127] The preparation process is the same as in Example 1, except that the support is replaced with ES757 silica gel support, which has an average particle size of 25 μm, a pore volume of 1.6 ml / g, and a specific surface area of ​​295 m². 2 / g. The supported catalyst contains 19wt% aluminum and 0.3wt% zirconium.

[0128] Comparative Example 2

[0129] Preparation of supported catalyst D2

[0130] The preparation process is the same as in Example 1, except that the metallocene compound is replaced with dimethylsilyl-bridged bis(2-methyl-4-phenyl-indenyl)zirconium dichloride, and the support is replaced with ES757 silica gel support, which has an average particle size of 25 μm, a pore volume of 1.6 ml / g, and a specific surface area of ​​295 m². 2 / g. The supported catalyst contains 19wt% aluminum and 0.3wt% zirconium.

[0131] Preparation of ultra-high molecular weight polyethylene:

[0132] Polymerization was carried out in a 1.0L high-pressure reactor. The reactor was first purged with dry nitrogen, then 500 mL of n-hexane was added, followed by 3 mL of a 1 mol / L triethylaluminum n-hexane solution. 5–50 mg of a supported metallocene catalyst was added, stirring was started, and ethylene was introduced while maintaining a certain pressure. Simultaneously, the temperature was raised to the reaction temperature, and the polymerization reaction was carried out for 2 hours to obtain powdered ultra-high molecular weight polyethylene. The results are shown in Table 2.

[0133] Table 2 Results of polymerization experiments using supported catalysts

[0134]

[0135] As can be seen from the polymerization experimental results in Table 2, the supported metallocene catalyst of this invention exhibits high activity in ethylene polymerization and can produce molecules with a molecular weight greater than 1×10⁻⁶. 6 Ultra-high molecular weight polyethylene (UHMWPE) with a molecular weight of g / mol can reach up to 4.30 × 10⁻⁶ g / mol at 1.0 MPa. 6 At g / mol and 2.0 MPa, the highest molecular weight that can be polymerized is 4.50 × 10⁻⁶ g / mol. 6 The highest polymerization activity was 4900 gPE / gCat, while the supported catalyst prepared using commercial silica gel supports showed lower catalytic activity, with a maximum polymerization activity of only 1560 gPE / gCat. Supported catalysts prepared using metallocene compounds not described in this invention exhibited low polymerization activity during ethylene polymerization, and the resulting polymers had molecular weights below 1×10⁻⁶ gPE / gCat. 6 g / mol.

Claims

1. A supported metallocene catalyst, comprising a metallocene compound, a cocatalyst, and a support, wherein the support is mesoporous silica with a dual-pore size distribution, and the metallocene compound has the structure shown in (I). in, L 1 L 2 Each is independently cyclopentadienyl and fluorenyl, L 1 L 2 Same or different; R 1 R 2 L respectively 1 L 2 Substituents on, R 1 R 2 Each is an alkyl or aryl group, each consisting of C1 to C6 atoms; p and q are R... 1 R 2 The quantities of p and q are 0, 1, 2 or 3, respectively; Z is -C(CH3)2- or -CPh2-, where Ph is phenyl; M is Ti, Zr or Hf; X is halogen or C1 to C4 alkyl.

2. The supported metallocene catalyst according to claim 1, characterized in that: L 1 It is cyclopentadienyl, L 2 It is fluorene-based; R 1 R 2 Each is an alkyl or phenyl group, C1 to C5; p = 0, q is 0, 1 or 2; X is a halogen or methyl group.

3. The supported metallocene catalyst according to claim 2, characterized in that... The metallocene compound is selected from at least one of the following compounds: isopropyl-bridged (cyclopentadienyl-fluorenyl)titanium dichloride; isopropyl-bridged (cyclopentadienyl-fluorenyl)zirconium dichloride; isopropyl-bridged (cyclopentadienyl-fluorenyl)hafnium dichloride; isopropyl-bridged (cyclopentadienyl-fluorenyl)dimethyltitanium; isopropyl-bridged (cyclopentadienyl-fluorenyl)dimethylzirconium; isopropyl-bridged (cyclopentadienyl-fluorenyl)dimethylhafnium; isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl) Titanium dichloride; Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)zirconium dichloride; Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)hafnium dichloride; Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)dimethyltitanium; Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)dimethylzirconium; Isopropyl-bridged (cyclopentadienyl-2,7-diphenylfluorenyl)dimethylhafnium; Isopropyl-bridged (cyclopentadienyl-2,7-ditert-butylfluorenyl) Titanium dichloride; Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)zirconium dichloride; Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)hafnium dichloride; Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethyltitanium; Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylzirconium; Isopropyl-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylhafnium; Diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethyltitanium; -di-tert-butylfluorenyl)titanium dichloride; diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)zirconium dichloride; diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)hafnium dichloride; diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethyltitanium; diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylzirconium; diphenylmethylene-bridged (cyclopentadienyl-2,7-di-tert-butylfluorenyl)dimethylhafnium.

4. The supported metallocene catalyst according to claim 1, characterized in that: The cocatalyst is at least one of alkylaluminoxane and organoboron compounds.

5. The supported metallocene catalyst according to claim 4, characterized in that: The cocatalyst is at least one selected from methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, triphenylcarbazo(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetra(pentafluorophenyl)borate, and N,N-dimethylbenzylammonium tetra(pentafluorophenyl)borate.

6. The supported metallocene catalyst according to claim 1, characterized in that: The silica has a bimodal pore size distribution, with the most probable pore sizes corresponding to the bimodal peaks being 1–10 nm and 20–50 nm, respectively; and / or, the silica has a specific surface area of ​​100–350 m² / g; and / or, the silica has a pore volume of 0.5–1.5 mL / g.

7. The supported metallocene catalyst according to claim 1, characterized in that: In the supported metallocene catalyst, the content of aluminum or boron in the co-catalyst is 12-20% by weight, and the content of M in the metallocene compound is 0.1-0.4% by weight.

8. A method for preparing a supported metallocene catalyst according to any one of claims 1 to 7, comprising the following steps: (a) Add solvent to the support, then add co-catalyst, and stir to obtain a suspension of the support loaded with co-catalyst; (b) Add metallocene compound slurry to the suspension, stir, and then wash and remove solvent; preferably, the amount of co-catalyst is 30 to 80 parts per 100 parts of the weight of the support, and the amount of metallocene compound is 1 to 5 parts.

9. The preparation method according to claim 8, characterized in that: In step (a), the co-catalyst is added at 50–100°C and stirred for 1–10 hours; in step (b), the metallocene compound slurry is added at 0–50°C and stirred for 30–180 minutes.

10. The use of the supported metallocene catalyst according to any one of claims 1 to 7 or the supported metallocene catalyst obtained according to any one of claims 8 to 9 in the preparation of ultra-high molecular weight polyethylene.

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