Supported metallocene catalyst and preparation method and application thereof

Abstract

The invention belongs to the technical field of olefin polymerization, and discloses a supported metallocene catalyst and a preparation method and application thereof, and the catalyst comprises a porous carrier, a metallocene compound, a promoter and a slow release agent. According to the supported metallocene catalyst disclosed by the invention, the slow release agent is added in the preparation process, so that the catalyst has the characteristic of low initial activity, and the long-term total polymerization activity of the catalyst can be improved. The supported metallocene catalyst provided by the invention can reduce the blocking risk of a catalyst feeding pipeline and significantly improve the operation stability of a polyolefin device.

Description

Technical Field

[0001] The present invention relates to the technical field of olefin polymerization, and more specifically, to a supported metallocene catalyst and a preparation method and application thereof. Background Art

[0002] Metallocene polyolefin catalysts have achieved breakthrough development due to the application of cocatalyst methylaluminoxane (MAO), and the catalytic activity has been greatly improved. Compared with traditional Ziegler-Natta catalysts, metallocene polyolefin catalysts are single-active-center catalysts that can accurately customize the molecular structure of polymers, including relative molecular mass and its distribution, comonomer content and its distribution on the molecular chain, etc.

[0003] Currently, most mainstream metallocene catalysts are supported catalysts. The co-catalyst has been added during the loading process, so no other co-catalyst is needed in the production of polymers. Supported metallocene catalysts can be used in many polymerization processes, such as slurry and gas phase polymerization methods.

[0004] Metallocene polyolefin catalysts have the characteristics of high initial activity, but react violently when in contact with polymer monomers, and are easy to break and agglomerate. How to smoothly transport the catalyst to the reactor and avoid clogging of the transport pipeline is a hot topic of research. There are currently two main solutions. One is to use inert gas or solvent as a transport medium to transport the catalyst to the reactor to avoid contact between the catalyst and the polymer monomer in the pipeline, but this method will increase the burden of subsequent separation and recovery modules; the other way is to use polymer monomers as a transport medium, by lowering the temperature of the transport medium or increasing its flow rate, to reduce the activity of the catalyst in the transport stage. These measures cannot completely solve the problem of feed blockage.

[0005] Patent application CN109906234A discloses a method for feeding a metallocene catalyst, wherein a metallocene catalyst supported by silica suspended in an aliphatic hydrocarbon and / or oil is conveyed to a solution or slurry polymerization reactor without prepolymerization at a speed of at least 1 m / s, and the conveying medium (propylene monomer) is controlled at a temperature of at least 50°C. This method can reduce or lower the agglomeration and blockage problems during the conveying process, but has certain requirements for the flow rate of the conveying medium. The usual practice is to increase the flow rate of the conveying medium or reduce the inner diameter of the conveying pipeline. Increasing the flow rate of the conveying medium may have a certain impact on the composition control of the main reactor, while reducing the size of the conveying pipeline involves changes to the device.

[0006] Patent application CN113039212A discloses using nitrogen, argon, ethane, propane and mixtures thereof as transport media to transport a catalyst system containing a metallocene catalyst to a gas phase polymerization reactor. The introduction of an inert medium will have a certain impact on the composition control in the reactor. Summary of the invention

[0007] The purpose of the present invention is to provide a supported metallocene catalyst and a preparation method and application thereof in view of the current status of the prior art. The supported metallocene catalyst prepared by the method releases its activity slowly when in contact with a polymerization monomer, has the characteristics of low initial activity, long duration of polymerization activity and no influence on the overall polymerization activity, can directly use the polymerization monomer as a conveying medium, can effectively reduce or avoid the clogging problem of the feeding equipment or the reactor caused by the violent reaction of the catalyst in the initial stage, and significantly improves the operation stability of the polyolefin device.

[0008] The first aspect of the present invention provides a supported metallocene catalyst, which comprises: a porous carrier, a metallocene compound, a co-catalyst and a sustained-release agent.

[0009] The second aspect of the present invention provides a method for preparing the above catalyst, which is selected from method one or method two;

[0010] Method 1:

[0011] (1) reacting the porous support and the co-catalyst in the presence of a first solvent;

[0012] (2) contacting and reacting the support obtained in step (1) with a metallocene compound solution in the presence of the first solvent;

[0013] (3) mixing the carrier obtained in step (2) with the sustained-release agent solution, and separating to obtain the supported metallocene catalyst;

[0014] The second method:

[0015] (1) reacting the porous support and the co-catalyst in the presence of a first solvent;

[0016] (2) Adding the metallocene compound solution and then the sustained-release agent solution to a reactor containing the first solvent and the carrier obtained in step (1), reacting the reactants, and separating to obtain the supported metallocene catalyst.

[0017] The third aspect of the present invention provides use of the above catalyst in the preparation of polyolefins.

[0018] The technical solution of the present invention has the following beneficial effects:

[0019] (1) The supported metallocene catalyst of the present invention has the characteristics of low initial activity due to the addition of a slow-release agent during the preparation process, and can improve the long-term total polymerization activity of the catalyst.

[0020] (2) The supported metallocene catalyst of the present invention can reduce the risk of catalyst feed line blockage and significantly improve the operating stability of the polyolefin device.

[0021] (3) Since the catalyst of the present invention has the characteristic of low initial activity, its initial reaction when in contact with the polymerization monomer is relatively mild, and the prepared polymer powder has the characteristics of low fine powder rate and agglomeration rate, thereby improving the operating stability of the device.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0024] The first aspect of the present invention provides a supported metallocene catalyst, which comprises: a porous carrier, a metallocene compound, a co-catalyst and a sustained-release agent.

[0025] According to the present invention, preferably, the porous carrier comprises an inorganic porous carrier or an organic porous carrier;

[0026] The inorganic porous carrier is preferably at least one of a silica carrier, an aluminum oxide carrier and a magnesium chloride carrier; the silica carrier preferably includes a silica gel carrier and / or a silica carrier;

[0027] The organic porous carrier is preferably a functionalized polyolefin carrier, and more preferably a polyethylene powder particle carrier and / or a polypropylene powder particle carrier.

[0028] According to the present invention, preferably, the metallocene compound is a non-bridged metallocene compound as shown in formula I or a bridged metallocene compound as shown in formula II;

[0029] Ar 1 Ar 2 M 1 Q 1 Q 2 Formula I; T Ar 3 Ar 4 M 2 Q 3 Q 4 Formula II;

[0030] Among them, M 1 and M 2 Each is independently selected from elements of Groups 3 to 5 of the Periodic Table of the Elements, preferably a Group 4 transition metal, most preferably zirconium, titanium, hafnium or vanadium;

[0031] Q 1 , Q 2 , Q 3 and Q 4 are all σ ligands, and are each independently a hydrogen atom, a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkyl group, a phenyl group or a benzyl group;

[0032] Ar 1 ,Ar 2 ,Ar 3 and Ar 4 Each is independently selected from cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, substituted cyclopentadienyl, substituted indenyl, substituted tetrahydroindenyl or substituted fluorenyl; wherein the substituent is selected from at least one of a hydrocarbon group, a silyl group, a hydrocarbon group in which one or more hydrogen atoms and / or one or more carbon atoms are replaced by heteroatoms, and a silyl group in which one or more hydrogen atoms and / or one or more carbon atoms are replaced by heteroatoms, and the heteroatoms are selected from at least one of B, P, S and N;

[0033] Preferably, the substituents in the substituted cyclopentadienyl, substituted indenyl, substituted tetrahydroindenyl and substituted fluorenyl are optionally cyclic;

[0034] The T group is a bridging group selected from a divalent bridge -R' 1 R' 2 C-, -R' 1 C=CR' 2 -、-R' 1 R' 2 CC R' 3 R' 4 -、-R' 1 R' 2 Si-、-R' 1 R' 2 Si-Si R' 3 R' 4 -、-R' 1 R' 2 Ge-、-R' 1 R' 2 Ge-Ge R' 3 R' 4 -、-R' 1 R' 2 C-Ge R' 3 R' 4 -、-R' 1 R' 2 Si-Ge R' 3 R' 4 -or-R' 1 R' 2 Si-CR' 3 R'4 -; where R' 1 , R' 2 , R' 3 and R' 4 Each is independently selected from a hydrogen atom, a hydrocarbon group, a silyl group, a germyl group, a hydrocarbon group in which one or more carbon atoms are replaced by a heteroatom, a silyl group in which one or more carbon atoms are replaced by a heteroatom, or a germyl group in which one or more carbon atoms are replaced by a heteroatom, wherein the heteroatom is at least one of B, O, S, P and N;

[0035] The T group is most preferably -CH 2 -、-CH 2 CH 2 -、-C(CH 3 ) 2 -、-SiMe 2 -、-SiPh 2 -、-SiMePh-、-Si(CH 3 ) 2 -CH 2 -、-SiPh 2 -CH 2 -、-Si(Me 3 ) 2 -SiPh 2 -or-SiMePh-CH 2 -.

[0036] In the present invention, the substitution in the substituted cyclopentadienyl, substituted indenyl, substituted tetrahydroindenyl and substituted fluorenyl means that one or more hydrogens are replaced.

[0037] In the present invention, M 1 and M 2 Can be the same or different; Q 1 , Q 2 , Q 3 and Q 4 can be all the same, at least one different from the others, or all different; Ar 1 ,Ar 2 ,Ar 3 and Ar 4 Can be all the same, at least one different from the others, or all different; R' 1 , R' 2 , R' 3 and R' 4 They may all be the same, at least one may be different from the others, or all may be different.

[0038] According to the present invention, the cocatalyst refers to any compound capable of converting the metallocene compound into an active center. Preferably, the cocatalyst comprises an alkylaluminoxane compound and / or a boron-containing compound; preferably, a C1-C10 alkylaluminoxane and / or an organic borate; the C1-C10 alkylaluminoxane is more preferably at least one selected from methylaluminoxane, ethylaluminoxane and butylaluminoxane; the organic borate is more preferably at least one selected from tetraphenylborate, tetrakis(p-phenyl)borate, tetrakis(o-,p-dimethylphenyl)borate, tetrakis(p-trifluoromethylphenyl)borate, tetrakis(pentafluorophenyl)borate, tetrakis(perfluorobiphenyl)borate and tetrakis(perfluoronaphthyl)borate;

[0039] The cation of the organic borate is an organic cation, and the organic cation is preferably at least one of trialkylammonium ion, alkylanilinium ion, tetraalkylphosphonium ion, tetraphenylphosphonium ion and phenylcarbonium;

[0040] The cocatalyst is most preferably methylaluminoxane and / or ethylaluminoxane.

[0041] According to the present invention, preferably, the sustained-release agent is one or more of an oligomer, an aliphatic compound, a derivative of an aliphatic compound, an aromatic compound and a derivative of an aromatic compound.

[0042] According to the present invention, preferably, the oligomer is a low molecular weight polymer formed by polymerization of one or more monomers selected from olefins, dienes, cyclic olefins, unsaturated carboxylic acids, unsaturated alcohols, saturated alcohols, saturated carboxylic acids, aldehydes, phenols, cycloalkanes, epoxy hydrocarbons, olefins in which one or more hydrogen atoms are substituted by heteroatoms, dienes in which one or more hydrogen atoms are substituted by heteroatoms, cyclic olefins in which one or more hydrogen atoms are substituted by heteroatoms, unsaturated carboxylic acids in which one or more hydrogen atoms are substituted by heteroatoms, unsaturated alcohols in which one or more hydrogen atoms are substituted by heteroatoms, saturated alcohols in which one or more hydrogen atoms are substituted by heteroatoms, saturated carboxylic acids in which one or more hydrogen atoms are substituted by heteroatoms, aldehydes in which one or more hydrogen atoms are substituted by heteroatoms, phenols in which one or more hydrogen atoms are substituted by heteroatoms, cycloalkanes in which one or more hydrogen atoms are substituted by heteroatoms, and epoxy hydrocarbons in which one or more hydrogen atoms are substituted by heteroatoms, wherein the heteroatom is at least one of F, Cl and Br; the polymerization is addition polymerization, condensation or ring-opening polymerization; preferably, the oligomer is selected from one or more of polyethylene, polypropylene, polybutene, polyester, polypropylene glycol ether and polyethylene glycol.

[0043] Preferably, the oligomer is a polymer having 10 to 4000 carbon atoms and an apparent viscosity at 140°C of less than 2000 mPa·s, more preferably an apparent viscosity at 140°C of less than 1000 mPa·s, and even more preferably an apparent viscosity at 140°C of less than 800 mPa·s;

[0044] According to the present invention, preferably, the aliphatic compound and the derivative of the aliphatic compound are independently saturated or unsaturated compounds;

[0045] The derivative of the aliphatic compound is an aliphatic compound in which one or more hydrogen atoms and / or one or more carbon atoms are replaced by a heteroatom, wherein the heteroatom is at least one of O, N, S, F and Cl;

[0046] The derivatives of the aromatic compounds are compounds obtained by halogenation, nitration, sulfonation, alkylation or acylation of the aromatic compounds.

[0047] The carbon number of the aliphatic compound, the derivative of the aliphatic compound, the aromatic compound and the derivative of the aromatic compound is 10 to 300, preferably 15 to 80;

[0048] The kinematic viscosity of aliphatic compounds, aliphatic compound derivatives, aromatic compounds and aromatic compound derivatives at 100°C is less than 500 mm 2 / s, preferably 100℃ kinematic viscosity <300mm 2 / s, and preferably the kinematic viscosity at 100°C is less than 200 mm 2 / s.

[0049] According to the present invention, preferably, the sustained-release agent is at least one of vaseline, paraffin, octadecane, hexadecane, octadecylnaphthalene, dicyclohexyloctadecylphosphine, 1,4-di(dodecyl)benzene, nonadecylcyclohexane, chloroheneicosane and tri-hexadecylamine.

[0050] According to the present invention, preferably, based on the total weight of the supported metallocene catalyst, the content of the sustained-release agent is 1 to 95wt%, preferably 5 to 80wt%, and more preferably 10-50wt%; the content of the porous carrier is 1 to 90wt%, preferably 5 to 80wt%; the content of the metallocene compound is 0.1 to 10wt%, preferably 0.1 to 5wt%; the content of the co-catalyst is 0.1 to 20wt%, preferably 0.1 to 10wt%; and the sum of the percentages of each component is 100%.

[0051] The second aspect of the present invention provides a method for preparing the above catalyst, which is selected from method one or method two;

[0052] Method 1:

[0053] (1) reacting the porous support and the co-catalyst in the presence of a first solvent;

[0054] (2) contacting and reacting the support obtained in step (1) with a metallocene compound solution in the presence of the first solvent;

[0055] (3) mixing the carrier obtained in step (2) with the sustained-release agent solution, and separating to obtain the supported metallocene catalyst;

[0056] The second method:

[0057] (1) reacting the porous support and the co-catalyst in the presence of a first solvent;

[0058] (2) Adding the metallocene compound solution and then the sustained-release agent solution to a reactor containing the first solvent and the carrier obtained in step (1), reacting the reactants, and separating to obtain the supported metallocene catalyst.

[0059] According to the present invention, preferably, in the method 1, in step (3), the carrier and the sustained-release agent solution are mixed once or multiple times;

[0060] The second method further comprises step (3), mixing the supported metallocene catalyst obtained in step (2) and the sustained-release agent solution once or multiple times, and separating to obtain the supported metallocene catalyst reinforced with the sustained-release agent.

[0061] In the present invention, in method 1, in step (3), mixing the carrier and the sustained-release agent solution multiple times means that the carrier obtained by mixing and separating with the sustained-release agent solution last time is mixed with the sustained-release agent solution again, and the multiple times is ≥1 times, and finally separating to obtain the supported metallocene catalyst reinforced with the sustained-release agent;

[0062] In method 2, in step (3), the supported metallocene catalyst obtained in step (2) and the sustained-release agent solution are mixed multiple times, which means that the supported metallocene catalyst obtained by mixing and separating with the sustained-release agent solution last time is mixed with the sustained-release agent solution again, and the multiple times is ≥1 times, and the supported metallocene catalyst reinforced with the sustained-release agent is finally separated.

[0063] According to the present invention, preferably, in the method 1:

[0064] In step (1), the reaction temperature is 30 to 80° C. and the reaction time is 3 to 6 hours;

[0065] In step (2), the reaction temperature is 0 to 100° C.; the solvent for preparing the metallocene compound solution is selected from at least one of toluene, benzene, xylene, hexane, heptane and cyclohexane, preferably selected from toluene and / or hexane;

[0066] In step (3), the mixing temperature is 50 to 150° C. and the mixing time is 0.1 to 6 hours;

[0067] The first solvent is selected from aromatic hydrocarbons and / or aliphatic hydrocarbons, preferably at least one selected from toluene, benzene, xylene, hexane, heptane and cyclohexane;

[0068] The solvent for preparing the sustained-release agent solution is selected from at least one of toluene, benzene and xylene;

[0069] In the sustained-release agent solution, the concentration of the sustained-release agent is 2 to 95 wt %, preferably 10 to 80 wt %;

[0070] Preferably, each step in the method 1 is carried out under an inert gas atmosphere.

[0071] In the present invention, preferably, in step (2) of method 1, after the metallocene compound solution is dripped, the reaction time is 1 to 120 minutes.

[0072] According to the present invention, preferably, in the second method:

[0073] In step (1), the reaction temperature is 30 to 80° C. and the reaction time is 3 to 6 hours;

[0074] In step (2), the reaction temperature is 50 to 150° C. and the reaction time is 0.1 to 6 hours; the solvent for preparing the metallocene compound solution is selected from at least one of toluene, benzene, xylene, hexane, heptane and cyclohexane, preferably selected from toluene and / or hexane;

[0075] The first solvent is selected from aromatic hydrocarbons and / or aliphatic hydrocarbons, preferably at least one selected from toluene, benzene, xylene, hexane, heptane and cyclohexane;

[0076] The solvent for preparing the sustained-release agent solution is selected from at least one of toluene, benzene and xylene;

[0077] In the sustained-release agent solution, the concentration of the sustained-release agent is 2 to 95 wt %, preferably 10 to 80 wt %;

[0078] Preferably, each step in the second method is carried out under an inert gas atmosphere.

[0079] In the present invention, in method 2, in step (3), the mixing temperature is 50 to 150° C., and the mixing time is 0.1 to 6 hours;

[0080] In the present invention, in the above method 1 and method 2, in step (1), after the porous carrier material and the promoter react, they can be washed and dried to obtain a solid powder loaded with the promoter; or they can be directly used in the reaction in the subsequent step (2) without washing and drying. The washing can be performed several times with the above first solvent, and the drying can be vacuum drying.

[0081] In the above method 1, when the carrier and the sustained-release agent solution are mixed for multiple times, the carrier obtained in the previous step may or may not be washed before drying, and the solvent used for washing is at least one of hexane, heptane and cyclohexane. In the above method 2, when the supported metallocene catalyst obtained in step (2) and the sustained-release agent solution are mixed for multiple times, the supported metallocene catalyst obtained in the previous step may or may not be washed before drying, and the solvent used for washing is at least one of hexane, heptane and cyclohexane.

[0082] In the above method 1 and method 2, preferably, the slurry containing the supported metallocene catalyst is washed and vacuum dried at an operating temperature of less than 50°C to finally obtain a dried supported metallocene catalyst. Preferably, the washing and vacuum drying operating temperature is less than 30°C. The washing solvent may be an aromatic hydrocarbon and / or an aliphatic hydrocarbon, such as at least one of toluene, benzene, xylene, hexane, heptane and cyclohexane, preferably at least one of hexane, heptane and cyclohexane.

[0083] The third aspect of the present invention provides use of the above catalyst in the preparation of polyolefins.

[0084] According to the present invention, preferably, the mixture containing the above catalyst and polymerization monomer is directly introduced into the main reactor without passing through the prepolymerization reactor; the polymerization monomer is a gas phase or liquid phase polymerization monomer.

[0085] According to the present invention, preferably, the polymerization temperature in the main reactor is 10-100°C, preferably 20-80°C.

[0086] In the present invention, the used polymerization reactor for preparing polyolefin includes but is not limited to pipeline reactor, loop reactor, kettle reactor, horizontal reactor, fluidized bed reactor or multiphase multi-zone reactor. According to whether prepolymerization is carried out in the reactor, it can be divided into prepolymerization reactor and main reactor.

[0087] In the present invention, the polymerization reaction used to prepare the polyolefin includes at least one of copolymerization and homopolymerization, and the polymerization monomer is particularly C containing carbon-carbon double bonds and carbon-carbon triple bonds. 2 -C 16 At least one of hydrocarbon and aromatic compounds, preferably C 2 -C 16 One or more olefin monomers, such as ethylene, propylene, butene-1, hexene-1, octene-1, propadiene, C 3 -C 12 At least one of cycloolefins, 1,3-butadiene, 1,4-butadiene, 1,2-pentadiene, 1,3-pentadiene, 1,4-pentadiene, vinylcyclopentane and vinylcyclohexane.

[0088] The present invention is further described below by examples:

[0089] The polymerization activity was obtained by calculating the molar ratio of the polymer to the active metal Zr in the catalyst.

[0090] Screening: The polymer powder was screened using a German FRITSCH vibration screening machine, and the proportion of polymer with a particle size of less than 0.18 mm was taken as the fine powder rate, and the proportion of polymer with a particle size of more than 2 mm was taken as the agglomeration rate.

[0091] Example 1

[0092] Catalyst preparation

[0093] Step a: Add 40 g of silica carrier and 35 ml of toluene to a 250 ml glass bottle replaced with nitrogen, heat the system to 50°C, dropwise add a toluene solution of methylaluminoxane (MAO) (containing 14.7 g MAO), react for 4 hours, filter, wash 3 times with 35 ml of toluene, and drain to obtain a white carrier with good fluidity.

[0094] Step b: Add 40 g of the above-prepared catalyst-supporting carrier into a 500 ml glass bottle replaced with nitrogen, add 60 ml of toluene, start stirring, and dropwise add 40 ml of a toluene solution of rac-vinylbisindenyl zirconium dichloride (Beijing Bailingwei Technology Co., Ltd.) at room temperature, the molar ratio of MAO to rac-vinylbisindenyl zirconium dichloride is 100:1 (MAO:Zr). After the dropwise addition, react for 30 minutes under stirring, filter, wash with 60 ml of hexane, filter, and dry to obtain a light yellow powder with good fluidity, i.e., a metallocene compound-supported solid.

[0095] Step c: Place all the metallocene compound-loaded solid prepared in step b into a 500 ml glass bottle replaced with nitrogen, then introduce 100 g of a 30 wt % polyethylene wax (commercial product model: Honeywell AC-6) toluene solution, heat to 70° C., and stir and mix for 30 min.

[0096] Step d: skim off the supernatant of the slurry containing the supported metallocene catalyst obtained in the previous step, cool it to 20°C, wash it with hexane, replace it with nitrogen several times, and then remove the solvent in vacuo to prepare a supported metallocene catalyst MET-1 with a mass of 48.10 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.3wt%, the content of the sustained-release agent is 15.84wt%, the content of the co-catalyst MAO is 8.74wt%, and the remainder is a porous carrier.

[0097] Small scale polymerization experiment

[0098] In a 5L stainless steel autoclave, after nitrogen purging and multiple replacements with propylene, 2L of liquid propylene was added, the temperature was raised to 60°C, 2mL (0.9mol / L) of triisobutylaluminum hexane solution and 100mg of the above MET-1 catalyst were pressed into the reactor with high-pressure nitrogen, and after reacting for 5min, 0.5mL of ethanol was added to deactivate the catalyst. The temperature was lowered, vented, and dried to obtain a polymer powder.

[0099] The polymerization activity data are shown in Table 1.

[0100] Example 2

[0101] Catalyst preparation

[0102] The difference between this embodiment and embodiment 1 is only step c: all the metallocene compound-loaded solid prepared in step b is placed into a 500 ml glass bottle replaced with nitrogen, and then 110 g of a 30 wt % toluene solution of vaseline (commercial manufacturer: J&K) is introduced, the temperature is raised to 70° C., and stirring and mixing is started for 30 min.

[0103] In this embodiment, a supported metallocene catalyst MET-2 is prepared with a mass of 47.68 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.25 wt %, the content of the sustained-release agent is 15.11 wt %, the content of the co-catalyst MAO is 9.01 wt %, and the remainder is the porous carrier.

[0104] Small scale polymerization experiment

[0105] Same as Example 1, except that 100 mg of MET-1 catalyst was replaced by 100 mg of MET-2 catalyst. The polymerization activity data are shown in Table 1.

[0106] Example 3

[0107] Catalyst preparation

[0108] The difference between this embodiment and embodiment 1 is that step b and step c of embodiment 1 are performed simultaneously: 40g of the above-prepared catalyst-supported carrier is added to a 500ml glass bottle replaced with nitrogen, 60ml of toluene is added, stirring is started, 40ml of rac-vinylbisindenyl zirconium dichloride toluene solution is added dropwise at room temperature, and the molar ratio of MAO to rac-vinylbisindenyl zirconium dichloride is 100:1 in terms of MAO:Zr. After the dropwise addition is completed, 100g of 30wt% polyethylene wax (commercial product model: Honeywell AC-6) toluene solution is added, the temperature is raised to 70°C, and the reaction is stirred for 30min.

[0109] In this embodiment, a supported metallocene catalyst MET-3 is prepared with a mass of 47.83 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.25 wt %, the content of the sustained-release agent is 15.37 wt %, the content of the co-catalyst MAO is 8.80 wt %, and the remainder is the porous carrier.

[0110] Small scale polymerization experiment

[0111] Same as Example 1, except that 100 mg of MET-1 catalyst was replaced by 100 mg of MET-3 catalyst. The polymerization activity data are shown in Table 1.

[0112] Example 4

[0113] Catalyst preparation

[0114] The difference between this embodiment and embodiment 1 is only step c: all the metallocene compound-loaded solid prepared in step b is placed in a 500 ml glass bottle replaced with nitrogen, and then 200 g of a 30 wt % toluene solution of polyethylene wax (commercial product model: Honeywell AC-6) is introduced, the temperature is raised to 70° C., and stirring and mixing is started for 30 min.

[0115] In this embodiment, a supported metallocene catalyst MET-4 is prepared with a mass of 54.16 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.17 wt %, the content of the sustained-release agent is 24.14 wt %, the content of the co-catalyst MAO is 7.82 wt %, and the remainder is the porous carrier.

[0116] Small scale polymerization experiment

[0117] Same as Example 1, except that 100 mg of MET-1 catalyst was replaced by 100 mg of MET-4 catalyst. The polymerization activity data are shown in Table 1.

[0118] Example 5

[0119] Catalyst preparation

[0120] The difference between this embodiment and embodiment 1 is only step c: all the metallocene compound-supported solid prepared in step b is placed in a 500 ml glass bottle replaced with nitrogen, and then 50 g of a toluene solution of a polyethylene wax (commercially available product model: Honeywell AC-6) with a concentration of 30 wt% is introduced, the temperature is raised to 70° C., and stirring and mixing is started for 30 min; then after drying, 50 g of a toluene solution of a polyethylene wax (commercially available product model: Honeywell AC-6) with a concentration of 30 wt% is introduced, the temperature is raised to 70° C., and stirring and mixing is started for 30 min.

[0121] In this embodiment, a supported metallocene catalyst MET-5 is prepared with a mass of 48.30 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.23 wt %, the content of the sustained-release agent is 16.18 wt %, the content of the co-catalyst MAO is 8.82 wt %, and the remainder is the porous carrier.

[0122] Small scale polymerization experiment

[0123] Same as Example 1, except that 100 mg of MET-1 catalyst was replaced by 100 mg of MET-5 catalyst. The polymerization activity data are shown in Table 1.

[0124] Example 6

[0125] Catalyst preparation

[0126] The difference between this embodiment and embodiment 1 is only step c: all the metallocene compound-loaded solid prepared in step b is placed in a 500 ml glass bottle replaced with nitrogen, and then 200 g of a toluene solution of polyethylene glycol (commercial product model: Shanghai Aladdin Biochemical Technology Co., Ltd. PEG-8000) with a concentration of 15 wt% is introduced, the temperature is raised to 70° C., and stirring and mixing is started for 30 minutes.

[0127] In this embodiment, a supported metallocene catalyst MET-6 is prepared with a mass of 46.98 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.27 wt %, the content of the sustained-release agent is 13.86 wt %, the content of the co-catalyst MAO is 8.78 wt %, and the remainder is the porous carrier.

[0128] Small scale polymerization experiment

[0129] Same as Example 1, except that 100 mg of MET-1 catalyst was replaced by 100 mg of MET-6 catalyst. The polymerization activity data are shown in Table 1.

[0130] Comparative Example 1

[0131] Catalyst preparation

[0132] The difference between this comparative example and Example 1 is only step c: all the metallocene compound-supported solid prepared in step b is placed into a 500 ml glass bottle replaced with nitrogen, and then 100 g of toluene solution is directly introduced, the temperature is raised to 70° C., and stirring and mixing is started for 30 minutes.

[0133] In this comparative example, a supported metallocene catalyst MET-1-C is prepared with a mass of 40.58 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.42 wt%, the content of the co-catalyst MAO is 10.2 wt%, the content of the sustained-release agent is 0 wt%, and the remainder is the porous carrier.

[0134] Small scale polymerization experiment

[0135] Same as Example 1, except that 100 mg of MET-1 catalyst was replaced by 100 mg of MET-1-C catalyst. The polymerization activity data are shown in Table 1.

[0136] Comparative Example 2

[0137] Catalyst preparation

[0138] The difference between this comparative example and Example 3 is as follows: 40 g of the above-prepared catalyst-supported carrier is added to a 500 ml glass bottle replaced with nitrogen, 60 ml of toluene is added, stirring is started, and 40 ml of a toluene solution of rac-vinylbisindenyl zirconium dichloride is added dropwise at room temperature, and the molar ratio of MAO to rac-vinylbisindenyl zirconium dichloride is 100:1 (MAO:Zr). After the dropwise addition is completed, 100 g of toluene is added, the temperature is raised to 70°C, and the reaction is stirred for 30 minutes.

[0139] In this comparative example, a supported metallocene catalyst MET-3-C is prepared with a mass of 40.60 g, wherein, based on the total weight of the supported metallocene catalyst, the content of the metallocene compound is 1.48 wt%, the content of the co-catalyst MAO is 10.1 wt%, the content of the sustained-release agent is 0 wt%, and the remainder is the porous carrier.

[0140] Small scale polymerization experiment

[0141] Same as Example 1, except that 100 mg of MET-1 catalyst was replaced by 100 mg of MET-3-C catalyst. The polymerization activity data are shown in Table 1.

[0142] Example 7

[0143] Pilot polymerization experiment

[0144] MET-1 catalyst slurry (30wt%) at a flow rate of 4g / h and triisobutylaluminum hexane solution (0.3mol / L) at a flow rate of 60mL were mixed with 10°C liquid propylene at a flow rate of 15kg / h to enter the 75L loop reactor, and at the same time, 15kg / h liquid propylene entered the loop reactor through the axial flow pump flushing port. The reaction temperature was 70°C, and the discharge valve was controlled by the reactor pressure to perform intermittent discharge. The generated polymer powder was separated from the unreacted propylene monomer by flash evaporation, and then deactivated and dried.

[0145] The polymerization activity and screening data are shown in Table 1.

[0146] Example 8

[0147] Same as Example 7, except that the catalyst used is MET-2. The data are shown in Table 1.

[0148] Example 9

[0149] Same as Example 7, except that the catalyst used is MET-3. The data are shown in Table 1.

[0150] Example 10

[0151] Same as Example 7, except that the catalyst used is MET-4. See Table 1 for data.

[0152] Embodiment 11

[0153] Same as Example 7, except that the catalyst used is MET-5. See Table 1 for data.

[0154] Example 12

[0155] Same as Example 7, except that the catalyst used is MET-6. See Table 1 for data.

[0156] Comparative Example 3

[0157] Same as Example 7, except that the catalyst used is MET-1-C. The data are shown in Table 1.

[0158] Comparative Example 4

[0159] Same as Example 7, except that the catalyst used is MET-3-C. The data are shown in Table 1.

[0160] Table 1

[0161]

[0162] As can be seen from the table, the supported metallocene catalyst obtained by adding a slow-release agent during the preparation process has the characteristics of low initial activity and can improve the long-term total polymerization activity of the catalyst. It is important that the supported metallocene catalyst prepared by this method can reduce the risk of catalyst feed line blockage and significantly improve the operational stability of the polyolefin device. In addition, the present invention surprisingly found that because the catalyst has the characteristics of low initial activity, its initial contact reaction with the polymerization monomer is relatively mild, and the prepared polymer powder has the characteristics of low fine powder rate and low agglomeration rate, thereby improving the operational stability of the device.

[0163] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A supported metallocene catalyst, characterized in that: The catalyst comprises: a porous carrier, a metallocene compound, a co-catalyst and a slow-release agent.

2. The catalyst according to claim 1, wherein The porous carrier includes an inorganic porous carrier or an organic porous carrier; The inorganic porous carrier is preferably at least one of a silica carrier, an aluminum oxide carrier and a magnesium chloride carrier; the silica carrier preferably includes a silica gel carrier and / or a silica carrier; The organic porous carrier is preferably a functionalized polyolefin carrier, and more preferably a polyethylene powder particle carrier and / or a polypropylene powder particle carrier.

3. The catalyst according to claim 1, wherein The metallocene compound is a non-bridged metallocene compound of formula I or a bridged metallocene compound of formula II; Ar1 Ar2M1Q1 Q2 Formula Ⅰ; T Ar3 Ar4M2 Q3Q4 Formula II; Wherein, M1 and M2 are each independently selected from elements of Groups 3 to 5 of the Periodic Table of Elements, preferably transition metals of Group 4, most preferably zirconium, titanium, hafnium or vanadium; Q1, Q2, Q3 and Q4 are all sigma ligands, and are each independently a hydrogen atom, a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkyl group, a phenyl group or a benzyl group; Ar1, Ar2, Ar3 and Ar4 are each independently selected from cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, substituted cyclopentadienyl, substituted indenyl, substituted tetrahydroindenyl or substituted fluorenyl; wherein the substituent is selected from at least one of a hydrocarbon group, a silyl group, a hydrocarbon group in which one or more hydrogen atoms and / or one or more carbon atoms are replaced by heteroatoms, and a silyl group in which one or more hydrogen atoms and / or one or more carbon atoms are replaced by heteroatoms, and the heteroatoms are selected from at least one of B, P, S and N; Preferably, the substituents in the substituted cyclopentadienyl, substituted indenyl, substituted tetrahydroindenyl and substituted fluorenyl are optionally cyclic; The T group is a bridging group selected from a divalent bridge -R'1R'2C-, -R'1C=CR'2-, -R'1R'2C-C R'3R'4-, -R'1R'2Si-, -R'1R'2Si-Si R'3R'4-, -R'1R'2Ge-, -R'1R'2Ge-Ge R'3R'4-, -R'1R'2C-Ge R'3R'4-, -R'1R'2Si-Ge R'3R'4- or -R'1R'2Si-CR'3R'4-; wherein R'1, R'2, R'3 and R'4 are each independently selected from a hydrogen atom, a hydrocarbon group, a silyl group, a germyl group, a hydrocarbon group in which one or more carbon atoms are substituted by a heteroatom, a silyl group in which one or more carbon atoms are substituted by a heteroatom or a germyl group in which one or more carbon atoms are substituted by a heteroatom, and the heteroatom is at least one of B, O, S, P and N; The T group is most preferably -CH2-, -CH2CH2-, -C(CH3)2-, -SiMe2-, -SiPh2-, -SiMePh-, -Si(CH3)2-CH2-, -SiPh2-CH2-, -Si(Me3)2-SiPh2- or -SiMePh-CH2-.

4. The catalyst according to claim 1, wherein The cocatalyst comprises an alkylaluminoxane compound and / or a boron-containing compound; preferably a C1-C10 alkylaluminoxane and / or an organic borate; the C1-C10 alkylaluminoxane is more preferably at least one selected from methylaluminoxane, ethylaluminoxane and butylaluminoxane; the organic borate is more preferably at least one selected from tetraphenylborate, tetrakis(p-phenyl)borate, tetrakis(o-,p-dimethylphenyl)borate, tetrakis(p-trifluoromethylphenyl)borate, tetrakis(pentafluorophenyl)borate, tetrakis(perfluorobiphenyl)borate and tetrakis(perfluoronaphthyl)borate; The cation of the organic borate is an organic cation, and the organic cation is preferably at least one of trialkylammonium ion, alkylanilinium ion, tetraalkylphosphonium ion, tetraphenylphosphonium ion and phenylcarbonium; The cocatalyst is most preferably methylaluminoxane and / or ethylaluminoxane.

5. The catalyst according to claim 1, wherein The sustained-release agent is one or more of oligomers, aliphatic compounds, derivatives of aliphatic compounds, aromatic compounds and derivatives of aromatic compounds.

6. The catalyst according to claim 5, wherein The oligomer is a low molecular weight polymer formed by polymerization of one or more monomers selected from olefins, dienes, cyclic olefins, unsaturated carboxylic acids, unsaturated alcohols, saturated alcohols, saturated carboxylic acids, aldehydes, phenols, cycloalkanes, epoxy hydrocarbons, olefins in which one or more hydrogen atoms are replaced by heteroatoms, dienes in which one or more hydrogen atoms are replaced by heteroatoms, cyclic olefins in which one or more hydrogen atoms are replaced by heteroatoms, unsaturated carboxylic acids in which one or more hydrogen atoms are replaced by heteroatoms, unsaturated alcohols in which one or more hydrogen atoms are replaced by heteroatoms, saturated alcohols in which one or more hydrogen atoms are replaced by heteroatoms, saturated carboxylic acids in which one or more hydrogen atoms are replaced by heteroatoms, aldehydes in which one or more hydrogen atoms are replaced by heteroatoms, phenols in which one or more hydrogen atoms are replaced by heteroatoms, cycloalkanes in which one or more hydrogen atoms are replaced by heteroatoms, and epoxy hydrocarbons in which one or more hydrogen atoms are replaced by heteroatoms, wherein the heteroatom is at least one of F, Cl and Br; the polymerization is addition polymerization, condensation or ring-opening polymerization; preferably, the oligomer is selected from one or more of polyethylene, polypropylene, polybutylene, polyester, polypropylene glycol ether and polyethylene glycol. Preferably, the oligomer is a polymer having 10 to 4000 carbon atoms and an apparent viscosity at 140°C of less than 2000 mPa·s, more preferably less than 1000 mPa·s, and even more preferably less than 800 mPa·s.

7. The catalyst according to claim 5, wherein The aliphatic compound and the derivative of the aliphatic compound are each independently a saturated or unsaturated compound; The derivative of the aliphatic compound is an aliphatic compound in which one or more hydrogen atoms and / or one or more carbon atoms are replaced by a heteroatom, wherein the heteroatom is at least one of O, N, S, F and Cl; The derivatives of the aromatic compounds are compounds obtained by halogenation, nitration, sulfonation, alkylation or acylation of the aromatic compounds. The carbon number of the aliphatic compound, the derivative of the aliphatic compound, the aromatic compound and the derivative of the aromatic compound is 10 to 300, preferably 15 to 80; The kinematic viscosity of aliphatic compounds, aliphatic compound derivatives, aromatic compounds and aromatic compound derivatives at 100°C is less than 500 mm 2 / s, preferably 100℃ kinematic viscosity <300mm 2 / s, and preferably the kinematic viscosity at 100°C is less than 200 mm 2 / s.

8. The catalyst according to claim 5, wherein The sustained-release agent is at least one of vaseline, paraffin, octadecane, hexadecane, octadecylnaphthalene, dicyclohexyloctadecylphosphine, 1,4-di(dodecyl)benzene, nonadecylcyclohexane, chloroheneicosane and tri-hexadecylamine.

9. The catalyst according to claim 1, wherein Based on the total weight of the supported metallocene catalyst, the content of the sustained-release agent is 1 to 95wt%, preferably 5 to 80wt%, and more preferably 10-50wt%; the content of the porous carrier is 1 to 90wt%, preferably 5 to 80wt%; the content of the metallocene compound is 0.1 to 10wt%, preferably 0.1 to 5wt%; the content of the co-catalyst is 0.1 to 20wt%, preferably 0.1 to 10wt%; and the sum of the percentages of each component is 100%.

10. The method for preparing a catalyst according to any one of claims 1 to 9, characterized in that: The preparation method is selected from method one or method two; Method 1: (1) reacting the porous support and the co-catalyst in the presence of a first solvent; (2) contacting and reacting the support obtained in step (1) with a metallocene compound solution in the presence of the first solvent; (3) mixing the carrier obtained in step (2) with the sustained-release agent solution, and separating to obtain the supported metallocene catalyst; The second method: (1) reacting the porous support and the co-catalyst in the presence of a first solvent; (2) Adding the metallocene compound solution and then the sustained-release agent solution to a reactor containing the first solvent and the carrier obtained in step (1), reacting the reactants, and separating to obtain the supported metallocene catalyst.

11. The method for preparing a catalyst according to claim 10, wherein: In the method 1, in step (3), the carrier and the sustained-release agent solution are mixed once or multiple times; The second method further comprises step (3), mixing the supported metallocene catalyst obtained in step (2) and the sustained-release agent solution once or multiple times, and separating to obtain the supported metallocene catalyst reinforced with the sustained-release agent.

12. The preparation method according to claim 10 or 11, wherein: In the method 1: In step (1), the reaction temperature is 30 to 80° C. and the reaction time is 3 to 6 hours; In step (2), the reaction temperature is 0 to 100° C.; the solvent for preparing the metallocene compound solution is selected from at least one of toluene, benzene, xylene, hexane, heptane and cyclohexane, preferably selected from toluene and / or hexane; In step (3), the mixing temperature is 50 to 150° C. and the mixing time is 0.1 to 6 hours; The first solvent is selected from aromatic hydrocarbons and / or aliphatic hydrocarbons, preferably at least one selected from toluene, benzene, xylene, hexane, heptane and cyclohexane; The solvent for preparing the sustained-release agent solution is selected from at least one of toluene, benzene and xylene; In the sustained-release agent solution, the concentration of the sustained-release agent is 2 to 95 wt %, preferably 10 to 80 wt %; Preferably, each step in the method 1 is carried out under an inert gas atmosphere.

13. The preparation method according to claim 10 or 11, wherein: In the second method: In step (1), the reaction temperature is 30 to 80° C. and the reaction time is 3 to 6 hours; In step (2), the reaction temperature is 50 to 150° C. and the reaction time is 0.1 to 6 hours; the solvent for preparing the metallocene compound solution is selected from at least one of toluene, benzene, xylene, hexane, heptane and cyclohexane, preferably selected from toluene and / or hexane; The first solvent is selected from aromatic hydrocarbons and / or aliphatic hydrocarbons, preferably at least one selected from toluene, benzene, xylene, hexane, heptane and cyclohexane; The solvent for preparing the sustained-release agent solution is selected from at least one of toluene, benzene and xylene; In the sustained-release agent solution, the concentration of the sustained-release agent is 2 to 95 wt %, preferably 10 to 80 wt %; Preferably, each step in the second method is carried out under an inert gas atmosphere.

14. Use of the catalyst according to any one of claims 1 to 9 in the preparation of polyolefins.

15. The use according to claim 14, wherein: The mixed material containing the catalyst according to any one of claims 1 to 9 and the polymerization monomer is directly introduced into the main reactor without passing through the prepolymerization reactor; the polymerization monomer is a gas phase or liquid phase polymerization monomer.

16. The use according to claim 14, wherein: The polymerization temperature in the main reactor is 10-100°C, preferably 20-80°C.

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