Supported metallocene catalyst suitable for the production of polyolefins and its preparation method and use

Abstract

This invention relates to a supported metallocene catalyst suitable for the production of polyolefins, its preparation method, and its applications. The supported metallocene catalyst is prepared by loading a metallocene active component onto a composite support modified with aluminum and molybdenum (Al and Mo) obtained by stepwise modification of silica gel with alkylaluminum, benzoic acid, and MoCl5-oxygen-containing compound composite products. The metallocene active component includes one or more of bridged metallocenes, non-bridged metallocenes, and monometallocenes. Compared with existing technologies, the catalyst obtained by this invention has high catalytic activity and uniformly dispersed active centers. It can efficiently catalyze the homopolymerization of ethylene, copolymerization of ethylene with α-olefins, copolymerization of ethylene with conjugated dienes, and ternary copolymerization of ethylene with α-olefins and conjugated dienes, producing ethylene and ethylene copolymers with controllable structures and excellent performance. The products have regular particles, high bulk density, and excellent mechanical and processing properties, making them particularly suitable for the industrial production of multi-monomer copolymerized ethylene.

Description

Technical Field

[0001] This invention relates to the field of polyolefin catalyst technology, and in particular to a supported metallocene catalyst suitable for the production of polyolefins, its preparation method, and its application. Background Technology

[0002] Metallocene catalysts, due to their single active center, produce polyolefin products with well-defined molecular chains and uniform comonomer distribution, thus occupying a core position in the production of high-end polyolefins. Ethylene copolymers (especially binary or ternary copolymers of ethylene with α-olefins and conjugated dienes) are widely used in packaging, automotive, and building materials industries due to their combination of rigidity, toughness, and processability. However, traditional metallocene catalysts suffer from problems such as low comonomer insertion rates, poor selectivity for different monomer insertions, uncontrollable product molecular weight distribution, and low retention of double bonds in conjugated dienes when catalyzing multi-monomer copolymerization, making it difficult to meet the production requirements of high-end ethylene copolymers.

[0003] Supporting is a key means to improve the performance of metallocene catalysts. Silica gel has become a commonly used support for metallocene catalysts due to its controllable particle size, large specific surface area, and good mechanical stability.

[0004] In existing technologies, ethylene multi-monomer copolymerization catalysts often suffer from defects such as low activity, unstable comonomer insertion rate, wide product molecular weight distribution, and easy cross-linking of conjugated diene double bonds, which limit the industrial application of high-end ethylene copolymers. Therefore, developing a metallocene catalyst that combines high catalytic activity, high comonomer insertion rate, high double bond retention rate, and the ability to achieve multi-monomer synergistic copolymerization has become the key to solving the above problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing a supported metallocene catalyst suitable for the production of polyolefins, its preparation method, and its applications. This catalyst uses Al and Mo-modified silica gel as a composite support, solving the problems of low activity, low comonomer insertion rate, poor double bond retention, and poor product performance controllability in the copolymerization of ethylene with multiple monomers, as described in this invention. The invention also relates to a method for preparing a modified silica gel-supported metallocene catalyst, and its applications in the homopolymerization of ethylene, copolymerization of ethylene with α-olefins, copolymerization of ethylene with conjugated dienes, and terpolymerization of ethylene with α-olefins and conjugated dienes to prepare ethylene and ethylene copolymers.

[0006] The objective of this invention can be achieved through the following technical solutions: One of the technical solutions of the present invention is to provide a supported metallocene catalyst suitable for the production of polyolefins. The supported metallocene catalyst includes a composite support and a metallocene active component supported on the composite support. The composite support is an aluminum (Al) and molybdenum (Mo) modified silica gel composite support. The composite support is prepared by reacting silica gel sequentially with alkyl aluminum, benzoic acid, and MoCl5-oxygen-containing compound composite products.

[0007] Furthermore, the MoCl5-oxygen-containing compound complex product is prepared by reacting MoCl5 with an oxygen-containing compound in an organic solvent.

[0008] Furthermore, the oxygen-containing compound is selected from one or more of tetrahydrofuran, octanol, tributyl phosphate, and ethylene glycol dimethyl ether.

[0009] More preferably, the oxygen-containing compound is tetrahydrofuran.

[0010] Furthermore, the molar ratio of MoCl5 to the oxygen-containing compound is (0.01~50.0):1.

[0011] More preferably, the molar ratio of MoCl5 to the oxygen-containing compound is (0.1~5.0):1. This ratio ensures that MoCl5 and the oxygen-containing compound are fully coordinated to form a stable composite product, while avoiding the inhibition of catalytic activity caused by excessive oxygen-containing compound.

[0012] Furthermore, the molar ratio of the MoCl5-oxygenated compound composite product to silica gel is (0.01~50.0):1.

[0013] Furthermore, the molar ratio of the MoCl5-oxygenated compound composite product to silica gel is (0.05~1.0):1, which can achieve uniform dispersion of Mo on the silica gel surface, avoid the decrease in catalytic activity caused by agglomeration, and at the same time ensure the synergistic effect of Mo and methylaluminoxane.

[0014] Furthermore, the silica gel is dehydrated and activated silica gel with an average particle size of 10-100 micrometers and a specific surface area of ​​200-800 m². 2 / g, pore volume 0.5~2.0cm 3 / g.

[0015] Furthermore, the dehydration and activation treatment of the silica gel is carried out under the protection of inert gases such as nitrogen or argon, with gradient fluidized drying at 100~600℃, and constant temperature at 100℃ for 2~4 hours, to completely remove physical water and molecular water on the surface of the silica gel, significantly improving the bonding force between silica gel and alkyl aluminum, and laying the foundation for subsequent modification.

[0016] Furthermore, the alkylaluminum is selected from one or more of trimethylaluminum, triethylaluminum, and triisobutylaluminum.

[0017] More preferably, the alkylaluminum is trimethylaluminum.

[0018] Furthermore, the molar ratio of the alkyl aluminum to the silica gel is (0.01~50):1.

[0019] More preferably, the molar ratio of the alkyl aluminum to the silica gel is (0.5~5):1:1.

[0020] Furthermore, the molar ratio of benzoic acid to alkyl aluminum is (0.01~50):1.

[0021] More preferably, the molar ratio of benzoic acid to alkyl aluminum is (0.8~1.5):1. This ratio can ensure that the alkyl aluminum reacts fully with the hydroxyl groups on the surface of the silica gel, and benzoic acid can efficiently catalyze the hydrolysis of alkyl aluminum to generate methylaluminoxane, which is then cured in situ on the surface of the silica gel. At the same time, the carboxylic acid structure of benzoic acid can improve the loading stability of methylaluminoxane.

[0022] Further, the metallocene active component is a metallocene compound with the general formula CpxMAy, where x≥1; M is a transition metal of group IVB, VB or VIB; Cp represents an unsubstituted or substituted cyclopentadienyl ligand, indene ligand, fluorenyl ligand, benzo[a]indene ligand, dibenzo[a]fluorenyl ligand or benzo[a]fluorenyl ligand; A is one or more of amines, ethers, carboxylic acids, dienes, phosphines, halogens, hydrogen atoms, and alkyl groups; (x+y) equals the valence of M.

[0023] More preferably, x=2.

[0024] More preferably, M is Ti, Zr, or Ha.

[0025] Furthermore, the metallocene active component includes one or more of bridged metallocene compounds, non-bridged metallocene compounds, and monometallocene compounds.

[0026] Furthermore, the bridging metallocene compound is selected from one or more of rac-ethylenebis(1-indenyl)zirconia, rac-dimethylsilylbis(2-methylindenyl)zirconia, and isopropylidenecyclopentadienylfluorenylzirconia.

[0027] Furthermore, the non-bridged metallocene compound is selected from one or more of zirconium dichloride, titanium dichloride, bis(n-butylcyclopentadienyl)zirconia, and bis(pentamethylcyclopentadienyl)zirconia.

[0028] Furthermore, the monoclonal metallocene compound is selected from one or more of cyclopentadienyl zirconium trichloride, cyclopentadienyl titanium trichloride, and pentamethylcyclopentadienyltriethoxyzirconium.

[0029] Furthermore, the loading of the metallocene active component is 0.01~5.0 wt% of the composite support mass, preferably 0.05~3.0 wt%. This loading ensures sufficient dispersion of the active centers, avoids agglomeration of the active centers due to excessive loading, and ensures high catalytic efficiency and copolymerization selectivity of the catalyst.

[0030] The second technical solution of the present invention is to provide a method for preparing a supported metallocene catalyst suitable for the production of polyolefins. This method refers to the preparation idea of ​​solid methylaluminoxane and achieves synergistic loading of Mo and methylaluminoxane on the surface of silica gel through a three-step modification process. The steps are simple, the conditions are mild, and it is suitable for industrial scale-up.

[0031] Furthermore, the preparation method includes the following steps: (1) Add silica gel (dehydrated and activated silica gel) to an organic solvent and disperse it by ultrasonication to obtain a silica gel suspension; (2) Under the protection of an inert gas, alkyl aluminum is added dropwise to the silica gel suspension in step (1), and the reaction is carried out at a set temperature to obtain an alkyl aluminum modified silica gel system. (3) Add benzoic acid to the alkyl aluminum modified silica gel system in step (2), and react in steps with controlled temperature to generate and solidify methyl aluminum oxane in situ on the silica gel surface to obtain Al modified silica gel carrier. (4) Add the MoCl5-oxygen-containing compound composite product to the Al-modified silica support in step (3), react at a set temperature, and after filtration, washing and drying, obtain the Al and Mo composite modified silica support. (5) Disperse the Al and Mo composite modified silica composite carrier from step (4) in an organic solvent, add the metallocene active component, stir and impregnate at a set temperature to load the metallocene onto the composite carrier, and obtain the metallocene-loaded silica composite carrier. (6) The metallocene-supported silica composite support from step (5) is filtered, solvent washed to remove excess metallocene active components, and dried to obtain a metallocene catalyst product (a supported metallocene catalyst suitable for the production of polyolefins).

[0032] Furthermore, the preparation of the MoCl5-oxygen-containing compound complex product includes the following process: MoCl5 was reacted with an oxygen-containing compound in an organic solvent to prepare a MoCl5-oxygen-containing compound composite product.

[0033] Furthermore, the reaction temperature of MoCl5 with oxygen-containing compounds in organic solvents is -20 to 60°C, and the reaction time is 0.5 to 3 hours.

[0034] Furthermore, the reaction of MoCl5 with oxygen-containing compounds in an organic solvent is a stirred reaction at a stirring speed of 100-200 rpm. After the reaction is complete, Al-modified silica support is directly added without separation.

[0035] Further, in step (1), the organic solvent is selected from one or more of toluene, xylene, n-hexane, kerosene, and dichlorobenzene.

[0036] Furthermore, in step (2), the reaction temperature is -50~100℃, the reaction time is 1~4h, and stirring is carried out during the reaction at a speed of 100~300rpm.

[0037] Further, in step (3), the stepwise temperature-controlled reaction is as follows: first, the reaction is carried out at -15~-20℃ for 0.5~2h, then the temperature is raised to 60~80℃ for 24~32h, and finally the temperature is raised to 90~110℃ for 8~16h.

[0038] Further, in step (3), after the stepwise temperature-controlled reaction is completed, n-hexane is added to the reaction system to precipitate, the volume ratio of n-hexane to the reaction system is (3~6):1, and the temperature at which n-hexane is added is 20~50℃.

[0039] Furthermore, in step (4), the washing solvent is n-hexane, the drying treatment is vacuum drying, the drying temperature is 40~80℃, and the drying time is 4~8h.

[0040] Furthermore, in step (5), the impregnation reaction temperature is -50~120℃, the reaction time is 2~8h, and the stirring speed is 150~400rpm.

[0041] Furthermore, in step (5), the organic solvent is selected from one or more of toluene, xylene, n-hexane, kerosene, and dichlorobenzene, with toluene being preferred.

[0042] Further, in step (6), the solvent is n-hexane, the drying process is vacuum drying, the drying temperature is 40~80℃, and the drying time is 4~12h.

[0043] Furthermore, the preparation method specifically includes the following steps: (1) Dehydration and activation of silica gel: Place silica gel in a fluidized bed and dry it in a gradient fluidized bed at 100~600℃ under nitrogen and / or argon protection. Maintain the temperature at 100℃ for 2~4h for 2h. After cooling to room temperature, seal and store it in nitrogen to obtain dehydration and activation silica gel. (2) Alkyl aluminum modification of silica gel: Dehydrated and activated silica gel is added to an organic solvent and ultrasonically dispersed for 10-30 min to obtain a silica gel suspension with a mass concentration of 5-20 wt%; under inert gas protection, alkyl aluminum is added dropwise to the silica gel suspension at a drop rate of 0.5-2 mL / min, and the mixture is stirred at 100-300 rpm for 1-4 h at 10-50 °C to obtain an alkyl aluminum modified silica gel system; (3) Preparation of silica-supported methylaluminoxane: Add benzoic acid to the alkylaluminum modified silica system in step (2) at a dropping rate of 0.5~1.5 mL / min. First, react at 15~30℃ for 0.5~2 h, then raise the temperature to 60~80℃ for 24~32 h, and finally raise the temperature to 90~110℃ for 8~16 h. After the reaction is completed, cool the system to 20~50℃, add n-hexane with a volume of 3~6 times that of the reaction system, and precipitate solid to obtain silica-supported methylaluminoxane system (Al modified silica support). (4) Preparation of MoCl5-oxygen-containing compound composite modification and composite support: MoCl5 and oxygen-containing compounds were added to an organic solvent in proportion and stirred at 100-200 rpm at 20-50℃ for 0.5-3h to obtain MoCl5-oxygen-containing compound composite product (no separation required); the composite product system was directly added to the silica-supported methylaluminoxane system in step (3) and stirred at 150-350 rpm at 20-60℃ for 1-5h; after filtration, washing with n-hexane 3-6 times, and vacuum drying at 40-80℃ for 4-8h, Al and Mo composite modified silica-containing composite support was obtained; (5) Metallocene loading: The Al and Mo composite modified silica composite carrier from step (4) is dispersed in an organic solvent to obtain a carrier suspension with a mass concentration of 5~15wt%. The metallocene active component is added and stirred and impregnated at 150~400rpm at 20~80℃ for 2~8h to load the metallocene onto the composite carrier, thus obtaining a metallocene-loaded silica composite carrier. (6) Post-treatment of catalyst: The impregnated product (metallocene-supported silica composite support obtained in step (5)) is filtered, washed with n-hexane 3 to 5 times to remove excess metallocene active components, and vacuum dried at 40 to 80°C for 4 to 12 hours to obtain metallocene catalyst product.

[0044] Furthermore, the organic solvent is selected from one or more of toluene, xylene, n-hexane, kerosene, and dichlorobenzene, preferably a mixed solvent with a volume ratio of toluene to n-hexane of (1~3):1. This solvent system can simultaneously ensure the dispersibility of silica gel, alkyl aluminum, benzoic acid, MoCl5-oxygenated compound composite products and metallocene, avoid agglomeration caused by excessively high local concentrations, and improve the reaction efficiency of each reaction step.

[0045] The third technical solution of this invention provides an application of a supported metallocene catalyst suitable for the production of polyolefins. This supported metallocene catalyst is used in the homopolymerization of ethylene, copolymerization of ethylene with α-olefins, copolymerization of ethylene with conjugated dienes, or ternary copolymerization of ethylene with α-olefins and conjugated dienes to prepare ethylene and / or ethylene copolymers. This catalyst can efficiently catalyze the homopolymerization of ethylene and the binary / ternary copolymerization of ethylene with α-olefins and conjugated dienes, preparing ethylene and ethylene copolymers with controllable structures and excellent performance, suitable for high-end applications.

[0046] Furthermore, the α-olefin is selected from one or more of 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene, preferably 1-hexene.

[0047] Furthermore, the conjugated diene is selected from one or more of 1,3-butadiene, isoprene, 1,4-hexadiene, and 5-methylene-2-norbornene, preferably 1,4-hexadiene.

[0048] Furthermore, when the supported metallocene catalyst is used for ethylene homopolymerization, the process includes: adding solvent, ethylene, the supported metallocene catalyst and a co-catalyst to a reactor to carry out a polymerization reaction.

[0049] Furthermore, when the supported metallocene catalyst is used for the copolymerization of ethylene with α-olefins, the copolymerization of ethylene with conjugated dienes, or the terpolymerization of ethylene or α-olefin-conjugated dienes, the process includes: adding solvent, ethylene, comonomer, supported metallocene catalyst and cocatalyst to a reactor to carry out the polymerization reaction.

[0050] Furthermore, the comonomer is an α-olefin and / or a conjugated diene.

[0051] Furthermore, the molar ratio of the comonomer to ethylene is (0.001~10):1, and the proportion of each monomer can be flexibly adjusted according to the product performance requirements.

[0052] Furthermore, when the comonomer includes α-olefin and conjugated diene, the molar ratio of α-olefin to conjugated diene is (0.001~10):1.

[0053] Furthermore, the amount of supported metallocene catalyst added is such that the concentration of supported metallocene catalyst in the entire polymerization system is 0.01~200ppm, and the amount of co-catalyst added is such that the concentration of co-catalyst in the entire polymerization system is 5~1000ppm, preferably triethylaluminum, which can effectively remove impurities in the system and improve catalyst activity.

[0054] Furthermore, the co-catalyst is selected from one or more of triethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

[0055] Furthermore, the polymerization reaction adopts a gas-phase or slurry process to meet the needs of industrial production; the polymerization reaction time is 1~8 hours.

[0056] Furthermore, the average particle size D50 of the obtained ethylene or ethylene copolymer product is 80~2000 micrometers, and the bulk density is 0.20~0.6 g / cm³. 3 .

[0057] Furthermore, the supported metallocene catalyst exhibits a polymerization efficiency of ≥4000 g copolymer / g·h, an α-olefin insertion rate of 0.1~15 mol%, a conjugated diene insertion rate of 0.05~15 mol%, a double bond retention rate of ≥90%, regular molecular chains, uniform distribution of comonomers, and excellent mechanical and processing properties, making it widely applicable in packaging films, automotive parts, pipes, and other fields.

[0058] The technical concept of this invention includes: Mo possesses unique electronic regulation capabilities and multi-component coordination characteristics, enabling it to synergize with metallocene active centers while optimizing the insertion efficiency of α-olefins and the double bond retention rate of conjugated dienes. Oxygen-containing compounds (such as tetrahydrofuran and octanol) can form stable composite products with MoCl5, significantly improving the dispersibility of Mo on the support surface and preventing aggregation. The preparation principle of solid methylaluminoxane provides a framework for the in-situ solidification of MAO, but currently there are no reports on technologies that combine silica gel-alkylaluminate-benzoic acid modification with MoCl5-oxygen-containing compound composite modification to prepare Al and Mo composite modified composite supports, and then load metallocene catalysts for the copolymerization of ethylene with α-olefins and conjugated dienes to prepare ethylene copolymers.

[0059] This invention designs a three-step silica gel modification process: alkyl aluminum oxane pretreatment, benzoic acid curing, and MoCl5-oxygen-containing compound composite modification. Alkyl aluminum oxane is cured onto the silica gel surface, and then the MoCl5-oxygen-containing compound composite product is introduced, allowing Mo and Al to form a synergistic effect on the silica gel surface. Mo can precisely regulate the electronic environment of the metallocene active center, while improving the insertion efficiency of α-olefins and the double bond retention rate of conjugated dienes; methyl aluminum oxane efficiently activates the metallocene, ensuring catalytic activity; and the silica gel support provides good mechanical stability, preventing support breakage during polymerization. The synergistic effect of these three factors enables the catalyst to exhibit excellent comprehensive performance in the copolymerization of ethylene monomers.

[0060] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention provides a supported metallocene catalyst suitable for the production of polyolefins, its preparation method and application. The supported metallocene catalyst uses Al and Mo-modified silica gel as a composite support, which takes into account the mechanical stability of silica gel, the activation characteristics of alkylaluminoxanes and the electronic regulation effect of Mo. The catalyst has high catalytic activity and meets the requirements of good insertion selectivity of α-olefin and conjugated diene comonomers.

[0061] 2) This invention provides a supported metallocene catalyst suitable for the production of polyolefins, its preparation method and application. The preparation method optimizes the silica gel modification process and achieves synergistic loading of Mo and methylaluminoxane through three-step modification. The steps are simple, the conditions are mild, and the Mo element is uniformly dispersed, avoiding the problem of Mo element agglomeration in traditional loading methods, which is suitable for industrial scale-up.

[0062] 3) This invention provides a supported metallocene catalyst suitable for the production of polyolefins, its preparation method and application. The catalyst can efficiently catalyze the homopolymerization of ethylene and the binary / ternary copolymerization of ethylene with α-olefins and conjugated dienes. The product has a controllable comonomer insertion rate, high double bond retention rate (≥90%), uniform particles, high bulk density, no obvious sticking phenomenon, and the product structure and performance can be flexibly adjusted according to application requirements. Detailed Implementation

[0063] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Component models, material names, connection structures, control methods, and other features not explicitly stated in this technical solution are considered to be common technical features disclosed in the prior art.

[0064] This invention relates to a supported metallocene catalyst (modified silica-supported metallocene catalyst) suitable for the production of polyolefins, its preparation method, and its applications. The catalyst is prepared by loading a metallocene active component onto a composite support obtained by stepwise modification of silica gel with alkylaluminum, benzoic acid, and MoCl5-oxygen-containing compounds, resulting in an aluminum and molybdenum (Al and Mo) composite modification. The metallocene active component includes one or more of bridged metallocenes, non-bridged metallocenes, and mono-metallocenes. The resulting catalyst exhibits high catalytic activity and uniformly dispersed active centers, enabling efficient catalysis of ethylene homopolymerization, ethylene-α-olefin copolymerization, ethylene-conjugated diene copolymerization, and ethylene-α-olefin-conjugated diene ternary copolymerization. This produces ethylene and ethylene copolymers with controllable structures and excellent performance. The products have regular particle size, high bulk density, and excellent mechanical and processing properties, making them particularly suitable for the industrial production of multi-monomer copolymerized ethylene.

[0065] In the examples below, unless otherwise specified, the reagents used are commercially available products and the methods employed are those known in the art.

[0066] The performance indicators of each polymer in the following examples and comparative examples were determined using the following methods: 1. Polymerization efficiency: Measured by the mass of copolymer produced per unit mass of catalyst per hour, expressed in g copolymer / g·h; 2. Product particle size D50: Measured using a laser particle size analyzer, unit is micrometer; 3. Bulk density: Measured according to ASTM-D1895, unit is g / cm³. 3 ; 4. α-olefin insertion rate and conjugated diene insertion rate: using... 13 Determined by C-NMR nuclear magnetic resonance spectroscopy, unit is mol%.

[0067] 5. Double bond retention rate: The ratio of the actual measured double bond content of the conjugated diene to the theoretical double bond content, expressed in units of %.

[0068] 6. Molecular weight distribution: determined by gel permeation chromatography (GPC).

[0069] Example 1 This embodiment provides a method for preparing and applying a supported metallocene catalyst (specifically, a metallocene catalyst with a bridged metallocene as the active component) suitable for the production of polyolefins (application in ethylene-1-butene-butadiene ternary copolymerization), including the following steps: 1. Dehydration and activation of silica gel: A sample with an average particle size of 25 micrometers and a specific surface area of ​​280 m² was prepared. 2 / g of silica gel was subjected to gradient fluidized drying at 100~600℃ under nitrogen protection, with a constant temperature of 100℃ for 3h per 100℃, and then sealed with nitrogen after cooling to room temperature to obtain dehydrated activated silica gel. 2. Alkyl aluminum modification: Take 10g of dehydrated activated silica gel, add 100mL of toluene and sonicate for 20min to obtain silica gel suspension; under nitrogen protection, add trimethylaluminum (molar ratio of trimethylaluminum to dehydrated activated silica gel 2:1) at a dropping rate of 1mL / min, and stir at 200rpm for 2h at -30℃ to obtain trimethylaluminum modified silica gel system. 3. Preparation of silica gel supported methylaluminoxane: Benzoic acid (molar ratio of benzoic acid to trimethylaluminum 1:1) was added dropwise to the above trimethylaluminum modified silica gel system at a dropwise rate of 1 mL / min. The reaction was carried out at 25 °C for 1 h, then heated to 70 °C for 28 h, and then heated to 100 °C for 12 h. After cooling to 30 °C, 400 mL of n-hexane was added, and a solid precipitated to obtain 15 g of silica gel supported methylaluminoxane system. 4. Preparation of MoCl5-tetrahydrofuran composite modification and composite support: 1g of MoCl5 and tetrahydrofuran were added to 50mL of toluene at a molar ratio of 1:2, and the mixture was stirred at 150rpm for 1h at 30℃ to obtain the composite product (MoCl5-oxygen-containing compound composite product); the composite product system was directly added to the above silica gel-supported methylaluminoxane system, and the mixture was stirred at 250rpm for 3h at 40℃; the mixture was filtered, washed four times with n-hexane, and dried under vacuum at 60℃ for 6h to obtain the composite support; 5. Metallocene support: Take 5g of composite support, add 50mL of toluene for dispersion, add 0.05g of rac-ethylenebis(1-indenyl)zirconium dichloride (loading 1.0wt%), stir and impregnate at 250rpm at 50℃ for 4h, filter, wash 4 times with n-hexane, and vacuum dry at 60℃ for 8h to obtain metallocene catalyst Cat-1. 6. Ethylene-1-hexene-butadiene terpolymerization: Using a slurry process, in a 2L steel pressure-resistant water-circulating temperature-controlled reactor, vacuum-nitrogen purging was carried out at 95℃ for 3 hours. 1L of toluene-n-hexane mixed solvent (volume ratio 1:1), 50mg Cat-1, 2mL triethylaluminum (co-catalyst concentration 200ppm), 20g of 1-hexene, and 5g of butadiene were added. 1.0MPa of ethylene gas was added, and copolymerization was carried out at 70℃ for 2 hours. The reaction was terminated with acidic ethanol, and the product was dried to obtain the ethylene terpolymer product.

[0070] Test results: The polymerization efficiency of this catalyst is 11580 g copolymer / g·h, and the bulk density is 0.35 g / cm³. 3 The 1-hexene insertion rate was 2.5 mol%, the 1,4-hexadiene insertion rate was 0.48 mol%, the double bond retention rate was 92%, and the molecular weight distribution was 2.7.

[0071] Example 2 This embodiment provides a method for preparing and applying a supported metallocene catalyst (specifically, a metallocene catalyst with a non-bridged metallocene as the active component) suitable for the production of polyolefins (application in ethylene-1-octene binary copolymerization), including the following steps: 1. Dehydration and activation of silica gel, alkyl aluminum modification, and preparation of silica gel supported on methylaluminoxane: Same as in Example 1; 2. Preparation of MoCl5-octanol composite modification and composite support: MoCl5 and octanol were combined in a molar ratio of 1:3, and the remaining steps were the same as in Example 1; 3. Metallocene support: Take 5g of composite support, add bis(pentamethylcyclopentadienyl)zirconia (loading 1.5wt%), stir and impregnate at 300rpm for 3h at 60℃, and the rest is the same as in Example 1 to obtain catalyst Cat-2; 4. Ethylene-1-octene binary copolymerization: In a 2L reactor, add 1L of toluene-n-hexane mixed solvent (volume ratio 1:1), 50mg Cat-2, 2mL of triisobutylaluminum (150ppm), 20g of 1-octene, and then add 1.0MPa of ethylene. Copolymerize at 80℃ for 2h. After terminating the reaction, dry to obtain the ethylene binary copolymer product.

[0072] Test results: The polymerization efficiency of this catalyst is 10860 g copolymer / g·h, and the bulk density is 0.32 g / cm³. 3 The 1-octene insertion rate was 2.9 mol%, with no conjugated diene involved, and the product molecular weight distribution was 2.5.

[0073] Example 3 This embodiment provides a method for preparing and applying a supported metallocene catalyst (specifically, a metallocene catalyst with a single metallocene as the active component) suitable for the production of polyolefins (for ethylene-isoprene binary copolymerization), including the following steps: 1. Dehydration and activation of silica gel, alkyl aluminum modification, and preparation of silica gel supported on methylaluminoxane: Same as in Example 1; 2. Preparation of MoCl5-tributyl phosphate composite modification and composite carrier: MoCl5 and tributyl phosphate were combined in a molar ratio of 1:1.5, and the remaining steps were the same as in Example 1; 3. Metallocene support: Take 5g of composite support, add cyclopentadienyl zirconium trichloride (loading amount 0.8wt%), stir and impregnate at 200rpm at 40℃ for 6h, and the rest is the same as in Example 1 to obtain catalyst Cat-3; 4. Ethylene-isoprene binary copolymerization: The polymerization conditions were the same as in Example 1 (ethylene-isoprene molar ratio 250:1), and an ethylene binary copolymer product was obtained.

[0074] Test results: The polymerization efficiency of this catalyst is 10320 g copolymer / g·h, and the bulk density is 0.33 g / cm³. 3 The isoprene insertion rate was 0.35 mol%, the double bond retention rate was 90%, and the molecular weight distribution was 2.8.

[0075] Comparative Example 1 This comparative example provides a method for preparing and applying a supported metallocene catalyst (specifically, a Mo-free silica gel-supported metallocene catalyst), comprising the following steps: 1. Dehydration and activation of silica gel, alkyl aluminum modification, and preparation of silica gel supported on methylaluminoxane: Same as in Example 1; 2. Directly supported metallocene: Take 5g of silica gel supported methylaluminoxane support, add rac-ethylene bis(1-indenyl)zirconium dichloride (loading 1.0wt%), and the remaining loading and copolymerization conditions are the same as in Example 1 to obtain catalyst Cat-D1.

[0076] Test results: The polymerization efficiency of the catalyst is 4850 g copolymer / g·h, the 1-hexene insertion rate is 1.0 mol%, the 1,4-hexadiene insertion rate is 0.12 mol%, the double bond retention rate is 75%, and the molecular weight distribution is 3.5.

[0077] Comparative Example 2 This comparative example provides a method for preparing and applying a supported metallocene catalyst (specifically, a conventional silica gel co-supported metallocene catalyst), comprising the following steps: 1. Take 10g of the dehydrated activated silica gel from Example 1 and add it to 100mL of toluene and ultrasonically disperse for 20min; 2. Add methylaluminoxane (MAO to silica gel mass ratio 1:1), stir and react at 30°C for 2 hours, then add rac-ethylenebis(1-indenyl)zirconium dichloride (loading 1.0 wt%), stir and impregnate at 50°C for 4 hours; 3. After filtration and washing with n-hexane four times, the mixture was dried under vacuum at 60°C for 8 hours to obtain the catalyst Cat-D2. 4. The copolymerization conditions are the same as in Example 1.

[0078] Test results: The polymerization efficiency of this catalyst is 4250 g copolymer / g·h, and the bulk density is 0.25 g / cm³. 3 The 1-hexene insertion rate was 0.5 mol%, the 1,4-hexadiene insertion rate was 0.08 mol%, the double bond retention rate was 68%, and there was a slight sticking phenomenon. The molecular weight distribution was 3.7.

[0079] Comparative Example 3 This comparative example provides a method for preparing and applying a supported metallocene catalyst, including the following steps: 1. Dehydration and activation of silica gel, alkyl aluminum modification, and preparation of silica gel supported on methylaluminoxane: Same as in Example 1; 2. MoCl5 was directly added to the above silica gel-supported methylaluminoxane system, and the mixture was stirred at 250 rpm for 3 h at 40 °C. After filtration and washing with n-hexane 4 times, the mixture was dried under vacuum at 60 °C for 6 h to obtain the composite support. 3. The same metallocene loading method as in Example 1 was used to obtain the catalyst Cat-D3; 4. The copolymerization conditions are the same as in Example 1.

[0080] Test results: The polymerization efficiency of this catalyst is 5560 g copolymer / g·h, and the bulk density is 0.26 g / cm³. 3 The 1-hexene insertion rate was 0.15 mol%, the 1,4-hexadiene insertion rate was 0.05 mol%, the double bond retention rate was 23%, there was no sticking to the vessel, and the molecular weight distribution was 3.9.

[0081] Table 1 shows a performance comparison between the examples and the comparative examples.

[0082] Table 1. Performance Comparison of Examples and Comparative Examples As shown in Table 1, the polymerization efficiency of Cat-1 in Example 1 is much higher than that of Cat-D1 in Comparative Example 1. The bulk density, α-olefin insertion rate, conjugated diene insertion rate, and double bond retention rate of Cat-1 in Example 1 are also significantly greater than those of Cat-D1 in Comparative Example 1. This indicates that the addition of MoCl5-oxygen-containing compound composite products can optimize key performance indicators such as polymerization efficiency, product bulk density, α-olefin insertion rate, conjugated diene insertion rate, and double bond retention rate.

[0083] As shown in Table 1, the polymerization efficiency of Cat-1 in Example 1 is much higher than that of Cat-D2 in Comparative Example 2. The bulk density, α-olefin insertion rate, conjugated diene insertion rate, and double bond retention rate of Cat-1 in Example 1 are also significantly greater than those of Cat-D2 in Comparative Example 2. In addition, Cat-D2 in Comparative Example 2 also exhibits slight sticking to the reactor. This indicates that, compared with the traditional silica gel co-loaded MAO, the method of the present invention can optimize key performance indicators such as polymerization efficiency, product bulk density, α-olefin insertion rate, conjugated diene insertion rate, and double bond retention rate.

[0084] As shown in Table 1, the polymerization efficiency of Cat-1 in Example 1 is much higher than that of Cat-D3 in Comparative Example 3. The bulk density, α-olefin insertion rate, conjugated diene insertion rate, and double bond retention rate of Cat-1 in Example 1 are also significantly greater than those of Cat-D3 in Comparative Example 3. In addition, Cat-D2 in Comparative Example 2 also exhibits slight sticking to the reactor. This indicates that, compared with directly adding MoCl5, the method of preparing MoCl5-oxygen-containing compound composite products of the present invention can optimize key performance indicators such as polymerization efficiency, product bulk density, α-olefin insertion rate, conjugated diene insertion rate, and double bond retention rate.

[0085] The modified catalyst of this invention is significantly superior to unmodified and traditional catalysts in terms of polymerization efficiency, α-olefin insertion rate, conjugated diene insertion rate, and double bond retention rate. It fully demonstrates the synergistic effect of Mo and methylaluminoxane and is more suitable for industrial production of high-end ethylene copolymers.

[0086] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A supported metallocene catalyst suitable for the production of polyolefins, characterized in that, The supported metallocene catalyst includes a composite support and a metallocene active component supported on the composite support; The composite carrier is an aluminum and molybdenum-modified silicone composite carrier; The composite carrier was prepared by reacting silica gel sequentially with alkyl aluminum, benzoic acid, and MoCl5-oxygen-containing compound composite products.

2. A supported metallocene catalyst suitable for the production of polyolefins according to claim 1, characterized in that, The MoCl5-oxygen-containing compound complex product is prepared by reacting MoCl5 with an oxygen-containing compound in an organic solvent; The oxygen-containing compound is selected from one or more of tetrahydrofuran, octanol, tributyl phosphate, and ethylene glycol dimethyl ether; The molar ratio of MoCl5 to the oxygen-containing compound is (0.01~50.0):1; The molar ratio of the MoCl5-oxygenated compound composite product to silica gel is (0.01~50.0):

1.

3. The supported metallocene catalyst suitable for the production of polyolefins according to claim 1, characterized in that, The silica gel is a dehydrated activated silica gel with an average particle size of 10-100 microns, a specific surface area of 200-800 m 2 / g, and a pore volume of 0.5-2.0 cm 3 / g. The silica gel was dehydrated and activated by gradient fluidized drying at 100-600°C under inert gas protection, with each 100°C held constant for 2-4 hours.

4. The supported metallocene catalyst suitable for the production of polyolefins according to claim 1, characterized in that, The alkylaluminum is selected from one or more of trimethylaluminum, triethylaluminum, and triisobutylaluminum; The molar ratio of the alkylaluminum to the silica gel is (0.01~50):1; The molar ratio of benzoic acid to alkyl aluminum is (0.01~50):

1.

5. The supported metallocene catalyst suitable for the production of polyolefins according to claim 1, characterized in that, The metallocene active component is a metallocene compound with the general formula CpxMAy, where x≥1; M is a transition metal of group IVB, VB, or VIB; Cp represents an unsubstituted or substituted cyclopentadienyl ligand, indene ligand, fluorenyl ligand, benzo[a]indene ligand, dibenzo[a]fluorenyl ligand, or benzo[a]fluorenyl ligand; A is one or more of amines, ethers, carboxylic acids, dienes, phosphines, halogens, hydrogen atoms, and alkyl groups; (x+y) equals the valence of M. The metallocene active component includes one or more of bridged metallocene compounds, non-bridged metallocene compounds, and mono-metallocene compounds. The metallocene active component includes one or more of bridged metallocene compounds, non-bridged metallocene compounds, and mono-metallocene compounds. The bridged metallocene compound is selected from one or more of rac-ethylenebis(1-indenyl)zirconia, rac-dimethylsilylbis(2-methylindenyl)zirconia, and isopropylidenecyclopentadienylfluorenylzirconia. The non-bridged metallocene compound is selected from one or more of zirconium dichloride, titanium dichloride, bis(n-butylcyclopentadienyl)zirconia, and bis(pentamethylcyclopentadienyl)zirconia. The monoclonal metallocene compound is selected from one or more of cyclopentadienyl zirconium trichloride, cyclopentadienyl titanium trichloride, and pentamethylcyclopentadienyltriethoxyzirconium. The loading of the metallocene active component is 0.01 to 5.0 wt% of the composite carrier mass.

6. A method for preparing a supported metallocene catalyst suitable for the production of polyolefins as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Add silica gel to an organic solvent and disperse it by ultrasonication to obtain a silica gel suspension; (2) Under the protection of an inert gas, alkyl aluminum is added dropwise to the silica gel suspension in step (1) and reacted to obtain an alkyl aluminum modified silica gel system. (3) Add benzoic acid to the alkyl aluminum modified silica gel system in step (2), and react in steps with controlled temperature to generate and solidify methyl aluminum oxane in situ on the silica gel surface to obtain Al modified silica gel carrier. (4) Add the MoCl5-oxygen-containing compound composite product to the Al-modified silica support in step (3), react, filter, wash and dry to obtain the Al and Mo composite modified silica support. (5) Disperse the Al and Mo composite modified silica composite carrier from step (4) in an organic solvent, add the metallocene active component, stir and impregnate to obtain the metallocene-loaded silica composite carrier. (6) The metallocene-supported silica composite carrier obtained in step (5) is filtered, solvent washed to remove excess metallocene active components, and dried to obtain the metallocene catalyst product.

7. The method for preparing a supported metallocene catalyst suitable for producing polyolefins according to claim 6, characterized in that, The preparation of the MoCl5-oxygen-containing compound complex product includes the following process: MoCl5 was reacted with an oxygen-containing compound in an organic solvent to prepare a MoCl5-oxygen-containing compound composite product. The reaction temperature of MoCl5 with oxygen-containing compounds in organic solvents is -20~60℃, and the reaction time is 0.5~3h. The reaction of MoCl5 with oxygen-containing compounds in an organic solvent is a stirred reaction at a stirring speed of 100-200 rpm. After the reaction is complete, Al-modified silica support is added directly without separation. The organic solvent is selected from one or more of toluene, xylene, n-hexane, kerosene, and dichlorobenzene.

8. The method for preparing a supported metallocene catalyst suitable for producing polyolefins according to claim 6, characterized in that, In step (1), the organic solvent is selected from one or more of toluene, xylene, n-hexane, kerosene, and dichlorobenzene; In step (2), the reaction temperature is -50~100℃, the reaction time is 1~4h, and the reaction is stirred at a speed of 100~300rpm. In step (3), the stepwise temperature-controlled reaction is as follows: first, the reaction is carried out at -15~-20℃ for 0.5~2h, then the temperature is raised to 60~80℃ for 24~32h, and finally the temperature is raised to 90~110℃ for 8~16h. In step (3), after the stepwise temperature-controlled reaction is completed, n-hexane is added to the reaction system to precipitate. The volume ratio of n-hexane to the reaction system is (3~6):1, and the temperature at which n-hexane is added is 20~50℃. The reaction temperature in step (4) is -20~100℃, the reaction time is 1~5h, and the stirring speed is 150~350rpm; In step (4), the washing solvent is n-hexane, the drying treatment is vacuum drying, the drying temperature is 40~80℃, and the drying time is 4~8h; In step (5), the impregnation reaction temperature is -50~120℃, the reaction time is 2~8h, and the stirring speed is 150~400rpm; In step (5), the organic solvent is selected from one or more of toluene, xylene, n-hexane, kerosene, and dichlorobenzene; In step (6), the solvent is n-hexane, the drying process is vacuum drying, the drying temperature is 40~80℃, and the drying time is 4~12h.

9. The application of a supported metallocene catalyst suitable for the production of polyolefins as described in any one of claims 1-5, characterized in that, The supported metallocene catalyst is used for ethylene homopolymerization, ethylene copolymerization with α-olefins, ethylene copolymerization with conjugated dienes, or ethylene terpolymerization with α-olefins and conjugated dienes to prepare ethylene and / or ethylene copolymers. The α-olefin is selected from one or more of 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene; The conjugated diene is selected from one or more of 1,3-butadiene, isoprene, 1,4-hexadiene, and 5-methylene-2-norbornene.

10. The method for applying a supported metallocene catalyst suitable for the production of polyolefins according to claim 9, characterized in that, When the supported metallocene catalyst is used for ethylene homopolymerization, the process includes: adding solvent, ethylene, supported metallocene catalyst and co-catalyst to a reactor to carry out a polymerization reaction; When the supported metallocene catalyst is used for the copolymerization of ethylene with α-olefins, the copolymerization of ethylene with conjugated dienes, or the terpolymerization of ethylene or α-olefins-conjugated dienes, the process includes: adding solvent, ethylene, comonomer, supported metallocene catalyst and cocatalyst to a reactor to carry out the polymerization reaction. The comonomer is an α-olefin and / or a conjugated diene; The molar ratio of the comonomer to ethylene is (0.001~10):1; The amount of supported metallocene catalyst added is such that the concentration of supported metallocene catalyst in the entire polymerization system is 0.01~200ppm, and the amount of co-catalyst added is such that the concentration of co-catalyst in the entire polymerization system is 5~1000ppm. The co-catalyst is selected from one or more of triethylaluminum, triisobutylaluminum, and diethylaluminum chloride; The polymerization reaction is carried out using slurry autoclave, slurry loop, or solution polymerization processes. The average particle size D50 of the obtained ethylene or ethylene copolymer product is 80-2000 microns, and the bulk density is 0.20-0.6 g / cm3 3 ; The polymerization efficiency of the supported metallocene catalyst is ≥4000 g copolymer / g·h, the α-olefin insertion rate is 0.1~15 mol%, and the conjugated diene insertion rate is 0.05~15 mol%.

Images