A metallocene catalyst and a method for preparing the same

Abstract

The application provides a metallocene catalyst and a preparation method thereof. The preparation method of the metallocene catalyst comprises the following steps: 1) performing a thermal activation treatment on a carrier to obtain an activated carrier; 2) loading a cocatalyst on at least part of the surface of the activated carrier to obtain a first intermediate product; and 3) after the first intermediate product is subjected to a first reaction with a metallocene compound, a pyridine compound is added to generate a second reaction, so as to obtain the metallocene catalyst; wherein the pyridine compound comprises an alkoxy group and / or a phenoxy group.

Description

Technical Field

[0001] This invention relates to the field of metallocene compound catalysis technology, and particularly to a metallocene catalyst and its preparation method. Background Technology

[0002] Metallocene catalysts represent another major breakthrough following Ziegler-Natta (ZN) catalysts. Since Professor Kaminsky of the University of Hamburg, Germany, first discovered the high activity of metallocene (MAO) catalysts for olefin polymerization in the early 1980s, this catalytic system has been a hot topic of research for scientists and is currently gradually replacing ZN catalysts.

[0003] Patent CN113173999A discloses a method for improving the activity of metallocene-catalyzed olefin polymerization, comprising: adding an electron donor with a fused-ring structure to the metallocene catalytic system for modification, thereby generating a π-π superposition effect with the fused-ring structure of the metallocene catalyst, enhancing the stabilizing effect of the fused-ring structure on the transition metal active center in the catalytic system, and thus improving the activity of catalytic olefin polymerization. However, this technology belongs to a homogeneous metallocene catalyst system, which cannot control the particle morphology of the polymer and cannot be applied to the current mainstream production processes of metallocene polyethylene or polypropylene, such as gas-phase polymerization, slurry polymerization, and liquid-phase bulk polymerization.

[0004] Patent CN101454356A discloses a single-point catalyst activator, its preparation method, and its use in catalysts and olefin polymerization. The method involves adding an ion-pair activator composition, wherein the cation includes a bronsted acid, and the anion's organic ligand has at least two heteroatoms covalently chelated to a metal atom. This chelation of the organic ligand with the metal atom increases the stability of the activator composition and significantly reduces the tendency for deactivation, especially for ligands without electron-withdrawing groups. However, this method is complex and requires a variety of chemical reagents, hindering its industrial application.

[0005] Patent CN106661154A discloses a catalyst activator, its preparation method, and its use in polymerization methods, including: enhancing catalyst activity by adding a perfluorinated group system based on at least one compound containing at least one active hydrogen moiety and at least one fluorine substituent, relying on these electron-withdrawing groups for stabilization. However, metallocene catalysts using perfluorophenol-based activators in this method are prone to deactivation and have a short lifespan.

[0006] Patent CN112679634A discloses a solid metallocene catalyst and its application, comprising: instead of using an inert support to load the metallocene active component, solidifying an aluminoxane and then loading the metallocene active component. Compared with traditional supported metallocene catalysts, the catalyst of this invention has more uniform active centers, higher catalyst loading, and better catalyst performance. It exhibits good performance and significantly improved polymerization activity in propylene polymerization. However, this technology, which improves the activity of the metallocene catalyst through the solidification of an aluminoxane, suffers from problems such as the large amount of aluminoxane required and the inability to control the catalyst particle morphology.

[0007] Therefore, it is necessary to provide a preparation method for metallocene catalysts that is simple to operate, uses few chemical reagents, and can produce highly active catalysts. Summary of the Invention

[0008] This invention provides a metallocene catalyst and its preparation method. The preparation method of the metallocene catalyst of this invention is simple to operate, uses few chemical reagents, and the prepared metallocene catalyst has excellent activity.

[0009] This invention provides a method for preparing a metallocene catalyst, comprising the following steps:

[0010] 1) The carrier is subjected to thermal activation treatment to obtain an activated carrier;

[0011] 2) The co-catalyst is loaded onto at least a portion of the surface of the activated support to obtain a first intermediate product;

[0012] 3) After the first intermediate product undergoes a first reaction with the metallocene compound, a pyridine compound is added to undergo a second reaction to obtain the metallocene catalyst;

[0013] The pyridine compound includes alkoxy and / or phenoxy compounds.

[0014] In the preparation method described above, the molar ratio of the pyridine compound to the metallocene compound is (0.01-1):1.

[0015] In the preparation method described above, the temperature in the second reaction is 0-60℃ and the time is 8-32h.

[0016] In the preparation method described above, the pyridine compound is selected from 2-butoxypyridine, 4-methoxypyridine, 3-methoxypyridine, 2-ethoxypyridine, 2-methoxypyridine, 4-phenoxypyridine, 2,6-dimethoxypyridine, 2,4-dimethoxypyridine, 3,5-dimethoxypyridine, 2,3-dimethoxypyridine, 4-benzyloxypyridine, 2,5-dimethoxypyridine, 2-phenoxypyridine, 2,3,6-trimethoxypyridine, 2-(tert-butoxy)pyridine, 2-(benzyloxy)pyridine, 2-isopropoxypyridine, 2,3-bis(benzyloxy)pyridine, 2,6-bis(benzyloxy)pyridine, 3-butoxy-2-ethoxypyridine, 2-ethoxy-3-propoxypyridine, 5-methoxypyridine-3-carboxylic acid methyl ester, 3-(dimethoxymethyl)-5-methoxypyridine, 5-(dimethoxymethyl)-5-methoxypyridine, etc. At least one of the following: (-(4-methoxymethyl)-2,3-dimethoxypyridine, 2-isopropyl-6-methoxypyridine, 2-methoxy-6-methylpyridine, 2-methoxy-5-methylpyridine, 2-methoxy-4-methylpyridine, 4-methoxy-2-methylpyridine, 3,4-dimethoxy-2-methylpyridine, 2-methoxy-3-methylpyridine, 2,3-dimethoxy-6-methylpyridine, 2-(4-methoxyphenyl)pyridine, 2-(2-methoxyethyl)pyridine, 4-methoxy-2-phenylpyridine, 2-methoxy-5-phenylpyridine, 5-methoxy-2-methylpyridine, 2-methoxy-6-p-tolylpyridine, 2,3-dimethoxy-5-(trimethylsilyl)pyridine, 2,3-dimethoxy-6-(trimethylsilyl)pyridine, and methyl 4-methoxy-2-pyridinecarboxylate.

[0017] In the preparation method described above, the temperature during the thermal activation treatment is 200-800℃ and the time is 6-48h.

[0018] In the preparation method described above, the molar ratio of the support to the co-catalyst is (1-30):1.

[0019] In the preparation method described above, in step 2), the temperature is 30-100℃ and the time is 2-6h.

[0020] In the preparation method described above, the molar ratio of the support to the metallocene compound is (100-5000):1.

[0021] In the preparation method described above, the temperature in the first reaction is -50 to 0°C, and the time is 1 to 24 hours.

[0022] This invention provides a metallocene catalyst, wherein it is prepared using the preparation method described above.

[0023] The method for preparing the metallocene catalyst of this invention uses electron donors from pyridine compounds containing alkoxy and / or phenoxy groups to modify the active site, thereby improving the activity of the metallocene catalyst. Simultaneously, it alters the electronic and steric effects around the active site, resulting in better hydrogen-modulated sensitivity of the metallocene catalyst and preventing deactivation. Furthermore, this preparation method is simple, uses few chemical reagents, and can be widely applied. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] A first aspect of the present invention provides a method for preparing a metallocene catalyst, comprising the following steps:

[0026] 1) The carrier is subjected to thermal activation treatment to obtain an activated carrier;

[0027] 2) The co-catalyst is loaded onto at least a portion of the surface of an activated support to obtain a first intermediate product;

[0028] 3) After the first intermediate product undergoes a first reaction with the metallocene compound, a pyridine compound is added to initiate a second reaction, yielding a metallocene catalyst;

[0029] Among them, pyridine compounds include alkoxy and / or phenoxy compounds.

[0030] The preparation method of the metallocene catalyst of the present invention specifically includes:

[0031] 1) The carrier is thermally activated to improve its activity, which facilitates the subsequent loading of active components onto the surface of the carrier, thereby obtaining an activated carrier;

[0032] 2) The co-catalyst is loaded onto part or all of the surface of the activated support to obtain the first intermediate product;

[0033] 3) The first intermediate product is reacted with the metallocene compound in a first reaction, the metallocene compound is loaded onto at least a portion of the surface of the activated support, and then a pyridine compound containing alkoxy and / or phenoxy groups is added to carry out a second reaction to obtain the metallocene catalyst.

[0034] The present invention does not impose any particular limitation on the carrier, which can be any carrier commonly used in the art. For example, the carrier can be selected from at least one of silica gel, magnesium chloride, alumina, montmorillonite, molecular sieve, polyethylene, polystyrene, polysiloxane, polyvinyl alcohol and polymethyl methacrylate. Further, the carrier can be silica gel.

[0035] This invention does not specifically limit the cocatalyst; it can be any cocatalyst commonly used in the art, such as alkylaluminoxane compounds or organoboron compounds. Alkylaluminoxane compounds include, but are not limited to, methylaluminoxane, ethylaluminoxane, butylaluminoxane, pentylaluminoxane, decylaluminoxane, modified methylaluminoxane, or mixtures thereof. Further, alkylaluminoxane compounds can be methylaluminoxane. Organoboron compounds include neutral boron compounds, borates, and combinations thereof. For example, organoboron compounds can be fluoroorganoboron compounds and fluoroorganoboronate compounds. Specifically, fluoroorganoboronate compounds include, but are not limited to, tetra(2,3,5,6-tetrafluorophenyl)borate, tetra(pentafluorophenyl)borate, N,N-dimethylaniline[3,5-bis(trifluoromethyl)phenyl]borate, or mixtures thereof. Fluoroorganoboron compounds include, but are not limited to, tris(pentafluorophenyl)borane, tris[3,5-bis(trifluoromethyl)phenyl]boron, or mixtures thereof.

[0036] This invention does not specifically limit the metallocene compound; the metallocene compound can be any metallocene compound commonly used in the art. In some embodiments, the general formula of the metallocene compound can be (Y)Cp*mMXn;

[0037] Wherein, Cp* is selected from substituted or unsubstituted cyclopentadiene, indenyl, fluorenyl; the substituent can be selected from C1 to C20 alkyl, alkoxy, silyl, arylalkoxy, hydroxyl or halogen, and indenyl and fluorenyl can also exist in the form of hydrogenation; m takes an integer from 1 to 4, and when m is 2 or greater, multiple Cp* can be the same or different;

[0038] Y is a bridging group. If the general formula is a non-bridging metallocene complex, then Y does not represent any element. If the general formula is a bridging metallocene compound, then Y is selected from SiR2, CR2, SiR2SiR2, CR2CR2, CR=CR, CR2SiCR2, GeR2, BR, or BR2, where R is selected from hydrogen atoms or groups with 20 or more carbon atoms. Groups with 20 or more carbon atoms can be selected from substituted or unsubstituted C1-C20 alkyl groups, substituted or unsubstituted C6-C20 aryl groups, or substituted or unsubstituted C1-C20 silyl groups. The substituent can be halogen, substituted or unsubstituted C1-C20 alkyl groups, or substituted or unsubstituted C6-C20 aryl groups. Further, R can be haloaryl, aryl-substituted alkyl, alkyl-substituted aryl, haloaryl-substituted alkyl, haloalkyl-substituted aryl, or silyl.

[0039] M is selected from transition metals in Group VIB or Group IVB of the periodic table. Further, M is selected from titanium, zirconium, and hafnium.

[0040] X is selected from one of hydrogen, halogen, substituted or unsubstituted hydrocarbon group, hydrocarbon oxygen group, aromatic hydrocarbon oxygen group, acid radical, and amino group;

[0041] n is an integer from 1 to 3 that satisfies the M valence state. When n is 2 or greater, multiple X groups can be the same or different.

[0042] In some embodiments, the metallocene compound may be selected from di(cyclopentadienyl)zirconia, di(cyclopentadienyl)hafnium dichloride, di(cyclopentadienyl)titanium dichloride, di(cyclopentadienyl)dimethylzirconia, di(cyclopentadienyl)dimethylhafnium, di(n-butylcyclopentadienyl)zirconia, di(pentamethylcyclopentadienyl)zirconia, di(tert-butylcyclopentadienyl)zirconia, dimethylbis(cyclopentadienyl)silylzirconia, di(indenyl)ethylene-bridged zirconium dichloride, or di(4,5,6,7-tetrahydro-1-indenyl)zirconia, dimethylsilylbis(2-methyl-4-phenylindenyl)zirconia, and mixtures thereof.

[0043] The method for preparing the metallocene catalyst of this invention uses electron donors from pyridine compounds containing alkoxy and / or phenoxy groups to modify the active site, thereby improving the activity of the metallocene catalyst. Simultaneously, it alters the electronic and steric effects around the active site, resulting in better hydrogen-modulated sensitivity of the metallocene catalyst and preventing deactivation. Furthermore, this preparation method is simple, uses few chemical reagents, and can be widely applied.

[0044] The present invention can also select specific parameters in the preparation method of metallocene catalysts in order to obtain high-performance metallocene catalysts while saving energy consumption.

[0045] In some embodiments of the present invention, when the molar ratio of pyridine compound to metallocene compound is (0.01-1):1, the pyridine compound and the metallocene compound are better matched, resulting in a metallocene catalyst with excellent activity. Further, the molar ratio of pyridine compound to metallocene compound can be (0.1-1):1.

[0046] In some embodiments of the present invention, when the temperature in the second reaction is 0-60°C and the time is 8-32 h, the reaction efficiency of the second reaction can be improved while saving energy, resulting in a more active metallocene catalyst. Further, the temperature in the second reaction can be 10-50°C and the time can be 10-20 h.

[0047] This invention does not particularly limit the pyridine compound and can use any pyridine compound commonly used in the art that contains an alkoxy or phenoxy group. In some embodiments of this invention, when the pyridine compound is selected from 2-butoxypyridine, 4-methoxypyridine, 3-methoxypyridine, 2-ethoxypyridine, 2-methoxypyridine, 4-phenoxypyridine, 2,6-dimethoxypyridine, 2,4-dimethoxypyridine, 3,5-dimethoxypyridine, 2,3-dimethoxypyridine, 4-benzyloxypyridine, 2,5-dimethoxypyridine, 2-phenoxypyridine, 2,3, 6-Trimethoxypyridine, 2-(tert-butoxy)pyridine, 2-(benzyloxy)pyridine, 2-isopropoxypyridine, 2,3-bis(benzyloxy)pyridine, 2,6-bis(benzyloxy)pyridine, 3-butoxy-2-ethoxypyridine, 2-ethoxy-3-propoxypyridine, 5-methoxypyridine-3-carboxylic acid methyl ester, 3-(dimethoxymethyl)-5-methoxypyridine, 5-(dimethoxymethyl)-2,3-dimethoxy When at least one of the following compounds is selected, such as 2-isopropyl-6-methoxypyridine, 2-methoxy-6-methylpyridine, 2-methoxy-5-methylpyridine, 2-methoxy-4-methylpyridine, 4-methoxy-2-methylpyridine, 3,4-dimethoxy-2-methylpyridine, 2-methoxy-3-methylpyridine, 2,3-dimethoxy-6-methylpyridine, 2-(4-methoxyphenyl)pyridine, 2-(2-methoxyethyl)pyridine, 4-methoxy-2-phenylpyridine, 2-methoxy-5-phenylpyridine, 5-methoxy-2-methylpyridine, 2-methoxy-6-p-tolylpyridine, 2,3-dimethoxy-5-(trimethylsilyl)pyridine, 2,3-dimethoxy-6-(trimethylsilyl)pyridine, and methyl 4-methoxy-2-pyridinecarboxylate, the pyridine compound can further enhance the activity of the metallocene catalyst.

[0048] The inventors also discovered that when the thermal activation treatment is carried out at a temperature of 200-800℃ for 6-48 hours, the support can be activated more fully while saving energy. This allows the activated support to better combine with subsequent co-catalysts, metallocene compounds, and pyridine compounds, resulting in metallocene catalysts with superior activity.

[0049] Furthermore, when the molar ratio of support to cocatalyst is (1-30):1, a metallocene catalyst with excellent activity can be prepared with less cocatalyst. In some embodiments, the molar ratio of support to cocatalyst can be (1-20):1.

[0050] In particular, when the temperature is 30-100℃ and the time is 2-6h in step 2), the co-catalyst can be more fully loaded on the surface of the activated support, improving the reaction efficiency of the subsequent first and second reactions, and obtaining a metallocene catalyst with better overall performance. In some embodiments, the temperature in step 2) can be 50-80℃ and the time can be 2-6 hours.

[0051] The inventors also discovered that when the molar ratio of the support to the metallocene compound is (100-5000):1, a more active metallocene catalyst can be obtained while saving raw materials.

[0052] Furthermore, when the temperature in the first reaction is -50 to 0°C and the time is 1 to 24 hours, highly active metallocene catalysts can be obtained more efficiently while saving energy. In some embodiments, the temperature in the first reaction can be -30 to 0°C and the time can be 4 to 8 hours.

[0053] In some embodiments of the present invention, the metallocene catalyst can be prepared by a method including the following steps:

[0054] 1) The carrier is calcined under nitrogen to perform thermal activation treatment to obtain activated carrier. The temperature of thermal activation treatment is 200-800℃ and the time is 6-48 hours.

[0055] 2) Under nitrogen protection, toluene is used as a solvent, an activated support is added, and then a co-catalyst is added. The molar ratio of support to co-catalyst is controlled at (1-30):1, the reaction temperature is 30℃-100℃, and the reaction time is 1-12 hours, so that the co-catalyst is loaded on at least part of the surface of the activated support to obtain the first intermediate product.

[0056] 3) The first intermediate and the metallocene compound are reacted in toluene to carry out a first reaction, with the molar ratio of the support to the metallocene compound controlled at (100-5000):1, the reaction temperature at -50℃ to 0℃, and the reaction time at 1-24 hours. Then, a pyridine compound is added, with the molar ratio of the pyridine compound to the metallocene compound controlled at (0.01-1):1, to carry out a second reaction at 0℃ to 60℃ and the reaction time at 8-32 hours, to obtain a slurry containing a metallocene catalyst.

[0057] In this invention, the slurry containing the metallocene catalyst after the reaction is completed can be directly used for the polymerization reaction, or the slurry containing the metallocene catalyst can be filtered, washed, and dried under reduced pressure to obtain a solid metallocene catalyst, which can then be used for the polymerization reaction.

[0058] A second aspect of the present invention provides a metallocene catalyst prepared using the preparation method of the first aspect.

[0059] The metallocene catalyst of the present invention uses an electron donor of a pyridine compound containing alkoxy and / or phenoxy groups for active site modification. This metallocene catalyst has excellent activity, and with the change of electronic and steric effects around the active site, the hydrogen sensitivity of the metallocene catalyst is improved, thus avoiding deactivation of the metallocene catalyst.

[0060] The technical solution of the present invention will be further described below with reference to specific embodiments. The sources of the chemical reagents in the embodiments and comparative examples of the present invention are as follows:

[0061] Toluene and hexane: Xilong Scientific Co., Ltd.;

[0062] Methylaluminoxane and silica gel: Grace Corporation, USA.

[0063] Example 1

[0064] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0065] Add 1 mol of Grace Davison 955 silica gel (carrier) and 0.2 mol of methylaluminoxane to 300 mL of toluene, which has been thermally activated at 600 °C for 12 hours, and heat to 50 °C for 6 hours.

[0066] Then, 0.001 mol of dimethylsilyldiindenezirconium dichloride was added, and the mixture was cooled to -15°C and reacted for 6 hours. Then, the mixture was heated to 10°C and 0.001 mol of 2-butoxypyridine was added and reacted for 12 hours. The mixture was washed three times each with toluene and hexane, and the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0067] Example 2

[0068] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0069] 1 mol of Grace Davison 955 silica gel and 0.2 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, were added to 300 mL of toluene, and the mixture was heated to 50°C and reacted for 6 hours.

[0070] Then, 0.005 mol of di-n-butylcyclopentadienylzirconium dichloride was added, and the mixture was cooled to -15°C and reacted for 6 hours. After that, the mixture was heated to 10°C and 0.0005 mol of 2,4-dimethoxypyridine was added and reacted for 12 hours. After filtering to remove the solvent, 300 mL of toluene was added, and the mixture was washed three times each with toluene and hexane. The solvent was then removed under negative pressure to obtain the metallocene catalyst.

[0071] Example 3

[0072] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0073] Add 1 mol of Grace Davison 955 silica gel and 0.2 mol of methylaluminoxane to 300 mL of toluene, which has been thermally activated at 600 °C for 12 hours, and heat to 80 °C for 2 hours.

[0074] Then, 0.0002 mol of bispentamethylcyclopentadienylzirconium dichloride was added, and the mixture was cooled to 0°C and reacted for 8 hours. After that, the mixture was heated to 50°C and 0.0002 mol of 2,3-dimethoxy-6-methylpyridine was added and reacted for 20 hours. After washing three times each with toluene and hexane, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0075] Example 4

[0076] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0077] Add 1 mol of Grace Davison 955 silica gel and 1 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, to 300 mL of toluene, and heat to 50°C for 6 hours.

[0078] Then, 0.0008 mol of dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride was added, and the mixture was cooled to -30°C and reacted for 6 hours. Then, the mixture was heated to 50°C and 0.0008 mol of 3-methoxypyridine was added and reacted for 10 hours. After washing with toluene and hexane three times each, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0079] Example 5

[0080] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0081] 1 mol of Grace Davison 955 silica gel and 0.08 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, were added to 300 mL of toluene, and the mixture was heated to 50°C and reacted for 5 hours.

[0082] Then, 0.001 mol of dimethylsilyldiindenezirconium dichloride was added, and the mixture was cooled to -15°C and reacted for 6 hours. After that, the mixture was heated to 50°C and 0.0008 mol of 2-ethoxypyridine was added and reacted for 10 hours. After washing three times each with toluene and hexane, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0083] Example 6

[0084] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0085] Add 1 mol of Grace Davison 955 silica gel and 0.7 mol of methylaluminoxane to 300 mL of toluene, which has been thermally activated at 600 °C for 12 hours, and heat to 60 °C for 2 hours.

[0086] Then, 0.006 mol of dimethylsilyldiindenezirconium dichloride was added, and the mixture was cooled to -10°C and reacted for 5 hours. After that, the mixture was heated to 50°C and 0.006 mol of 2,6-dimethoxypyridine was added and reacted for 20 hours. After washing three times each with toluene and hexane, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0087] Example 7

[0088] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0089] Add 1 mol of Grace Davison 955 silica gel and 0.7 mol of methylaluminoxane to 300 mL of toluene, which has been thermally activated at 600 °C for 12 hours, and heat to 60 °C for 2 hours.

[0090] Then, 0.006 mol of dimethylsilyldiindenezirconium dichloride was added, and the mixture was cooled to -10°C and reacted for 5 hours. After that, the mixture was heated to 30°C and 0.003 mol of 2-isopropoxypyridine was added and reacted for 10 hours. After washing with toluene and hexane three times each, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0091] Example 8

[0092] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0093] Add 1 mol of Grace Davison 955 silica gel and 0.1 mol of methylaluminoxane to 300 mL of toluene, which has been thermally activated at 600 °C for 12 hours, and heat to 60 °C for 2 hours.

[0094] Then, 0.006 mol of dimethylsilyldiindenezirconium dichloride was added, and the mixture was cooled to -10°C and reacted for 5 hours. After that, the mixture was heated to 30°C and 0.003 mol of 3,5-dimethoxypyridine was added and reacted for 18 hours. After washing with toluene and hexane three times each, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0095] Example 9

[0096] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0097] Add 1 mol of Grace Davison 955 silica gel and 0.7 mol of methylaluminoxane to 300 mL of toluene, which has been thermally activated at 600 °C for 12 hours, and heat to 60 °C for 2 hours.

[0098] Then, 0.006 mol of bispentamethylcyclopentadienylzirconium dichloride was added, and the mixture was cooled to -10°C and reacted for 5 hours. After that, the mixture was heated to 30°C and 0.003 mol of 2-methoxy-4-methylpyridine was added and reacted for 20 hours. After washing three times each with toluene and hexane, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0099] Example 10

[0100] The preparation method of the metallocene catalyst in this embodiment includes the following steps:

[0101] 1 mol of Grace Davison 955 silica gel and 0.2 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, were added to 300 mL of toluene, and the mixture was heated to 50°C and reacted for 6 hours.

[0102] Then, 0.001 mol of rac-ethylenebis(1-indenyl)zirconia was added, and the mixture was cooled to -15°C and reacted for 6 hours. After that, the mixture was heated to 30°C and 0.001 mol of 2,3-dimethoxy-6-methylpyridine was added and reacted for 20 hours. After washing three times each with toluene and hexane, the solvent was removed under negative pressure to obtain the metallocene catalyst.

[0103] Comparative Example 1

[0104] The preparation method of the metallocene catalyst in this comparative example includes the following steps:

[0105] 1 mol of Grace Davison 955 silica gel and 0.2 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, were added to 300 mL of toluene, and the mixture was heated to 50°C and reacted for 6 hours.

[0106] Then, 0.001 mol of dimethylsilyldiindenezirconium dichloride was added, and the mixture was cooled to -15°C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene catalyst.

[0107] Comparative Example 2

[0108] The preparation method of the metallocene catalyst in this comparative example includes the following steps:

[0109] 1 mol of Grace Davison 955 silica gel and 0.2 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, were added to 300 mL of toluene, and the mixture was heated to 50°C and reacted for 6 hours.

[0110] Then, 0.005 mol of di-n-butylcyclopentadienyl zirconium dichloride was added, and the mixture was cooled to -15°C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene catalyst.

[0111] Comparative Example 3

[0112] The preparation method of the metallocene catalyst in this comparative example includes the following steps:

[0113] Add 1 mol of Grace Davison 955 silica gel and 0.2 mol of methylaluminoxane to 300 mL of toluene, which has been thermally activated at 600 °C for 12 hours, and heat to 80 °C for 2 hours.

[0114] Then, 0.0002 mol of bispentamethylcyclopentadienylzirconium dichloride was added, and the mixture was cooled to 0°C and reacted for 8 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene catalyst.

[0115] Comparative Example 4

[0116] The preparation method of the metallocene catalyst in this comparative example includes the following steps:

[0117] Add 1 mol of Grace Davison 955 silica gel and 1 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, to 300 mL of toluene, and heat to 50°C for 6 hours.

[0118] Then, 0.0008 mol of dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride was added, and the mixture was cooled to -30°C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene catalyst.

[0119] Comparative Example 5

[0120] The preparation method of the metallocene catalyst in this comparative example includes the following steps:

[0121] 1 mol of Grace Davison 955 silica gel and 0.08 mol of methylaluminoxane, which have been thermally activated at 600°C for 12 hours, were added to 300 mL of toluene, and the mixture was heated to 50°C and reacted for 5 hours.

[0122] Then, 0.001 mol of dimethylsilyldiindenezirconium dichloride was added, and the mixture was cooled to -15°C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene catalyst.

[0123] Test case

[0124] The metallocene catalysts used in the examples and comparative examples were subjected to polymerization reactions, specifically including:

[0125] A 5-liter reactor was evacuated and purged with nitrogen three times. 1 kg of hexane was added, followed by 90 mmol of triethylaluminum and 0.05 g of hydrogen. After stirring for 30 minutes, 100 mg of metallocene catalyst was added. Ethylene was then introduced at 1 MPa at 80°C, and polymerization was carried out for 1 hour. The reaction was then terminated to obtain polyethylene. The catalytic activity and polymer properties were tested. The catalytic performance of the obtained catalyst and the relevant properties of the polyethylene product are shown in Table 1.

[0126] The polymer melt flow index (MFR) was determined according to GB / T3682-2000.

[0127] Catalyst activity = mass of prepared polyolefin / mass of catalyst solid component.

[0128] Table 1

[0129]

[0130]

[0131] As can be seen from Table 1, the metallocene catalyst in the embodiments of the present invention has higher catalytic activity when applied to the polymerization reaction, and the resulting polyethylene product has a lower melt index.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a metallocene catalyst, characterized in that, Includes the following steps: 1) The carrier is subjected to thermal activation treatment to obtain an activated carrier; 2) The co-catalyst is loaded onto at least a portion of the surface of the activated support to obtain a first intermediate product; 3) After the first intermediate product undergoes a first reaction with the metallocene compound, a pyridine compound is added to undergo a second reaction to obtain the metallocene catalyst; The pyridine compound includes alkoxy and / or phenoxy compounds.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the pyridine compound to the metallocene compound is (0.01-1):

1.

3. The preparation method according to claim 2, characterized in that, In the second reaction, the temperature is 0-60℃ and the time is 8-32h.

4. The preparation method according to claim 3, characterized in that, The pyridine compound is selected from 2-butoxypyridine, 4-methoxypyridine, 3-methoxypyridine, 2-ethoxypyridine, 2-methoxypyridine, 4-phenoxypyridine, 2,6-dimethoxypyridine, 2,4-dimethoxypyridine, 3,5-dimethoxypyridine, 2,3-dimethoxypyridine, 4-benzyloxypyridine, 2,5-dimethoxypyridine, 2-phenoxypyridine, 2,3,6-trimethoxypyridine, 2-(tert-butoxy)pyridine, 2-(benzyloxy)pyridine, 2-isopropoxypyridine, 2,3-bis(benzyloxy)pyridine, 2,6-bis(benzyloxy)pyridine, 3-butoxy-2-ethoxypyridine, 2-ethoxy-3-propoxypyridine, 5-methoxypyridine-3-carboxylic acid methyl ester, 3-(dimethoxymethyl)-5-methoxypyridine, 5-(dimethoxymethyl)-2 At least one of 3-dimethoxypyridine, 2-isopropyl-6-methoxypyridine, 2-methoxy-6-methylpyridine, 2-methoxy-5-methylpyridine, 2-methoxy-4-methylpyridine, 4-methoxy-2-methylpyridine, 3,4-dimethoxy-2-methylpyridine, 2-methoxy-3-methylpyridine, 2,3-dimethoxy-6-methylpyridine, 2-(4-methoxyphenyl)pyridine, 2-(2-methoxyethyl)pyridine, 4-methoxy-2-phenylpyridine, 2-methoxy-5-phenylpyridine, 5-methoxy-2-methylpyridine, 2-methoxy-6-p-tolylpyridine, 2,3-dimethoxy-5-(trimethylsilyl)pyridine, 2,3-dimethoxy-6-(trimethylsilyl)pyridine, and methyl 4-methoxy-2-pyridinecarboxylate.

5. The preparation method according to any one of claims 1-4, characterized in that, In the aforementioned thermal activation treatment, the temperature is 200-800℃ and the time is 6-48h.

6. The preparation method according to any one of claims 1-5, characterized in that, The molar ratio of the support to the co-catalyst is (1-30):

1.

7. The preparation method according to any one of claims 1-6, characterized in that, In step 2), the temperature is 30-100℃ and the time is 2-6 hours.

8. The preparation method according to any one of claims 1-7, characterized in that, The molar ratio of the carrier to the metallocene compound is (100-5000):

1.

9. The preparation method according to any one of claims 1-8, characterized in that, In the first reaction, the temperature is -50 to 0℃ and the time is 1 to 24 hours.

10. A metallocene catalyst, characterized in that, It was prepared using the preparation method according to any one of claims 1-9.

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