Process for continuous prepolymerization of polyolefin catalysts, its use and polyolefin polymerization process

Abstract

This invention relates to the field of olefin polymerization, and discloses a method for continuous prepolymerization of polyolefin catalysts, its application, and a method for polyolefin polymerization. A method for continuous prepolymerization of polyolefin catalysts includes: (1) reacting a first polymerizable monomer with a metallocene catalyst composition and / or a non-metallocene catalyst composition in a first prepolymerization reaction to obtain a first prepolymerized catalyst slurry; (2) reacting the first prepolymerized catalyst slurry obtained in step (1) with a second polymerizable monomer in a second prepolymerization reaction to obtain a second prepolymerized catalyst slurry; the prepolymerization ratio of the second prepolymerization reaction is 2-200 times that of the first prepolymerization reaction. The method provided by this invention can significantly reduce the risk of pipeline blockage and improve the operational stability of the equipment.

Description

Technical Field

[0001] This invention relates to the field of olefin polymerization, and more specifically, to a method for continuous prepolymerization of polyolefin catalysts, its application, and a method for polyolefin polymerization. Background Technology

[0002] Since the discovery of polyolefin catalysts, the main driving force behind their continuous development and progress has been the demands of industrial development. Meeting these demands requires catalysts with high polymerization activity and excellent stereoisotactic properties, thereby simplifying polymerization technology. Currently, the mainstream polyolefin catalyst is the zinc (Zn) catalyst, which possesses advantages such as high activity, high stereoisotacticity, and regular particle morphology. However, since the 1990s, metallocene and non-metallocene catalysts have developed rapidly. Compared to Zn catalysts, these types of catalysts produce polyolefin products with narrower molecular weight distributions and more uniform distribution of comonomers (stereodefects). However, the high initial activity of metallocene catalysts often leads to problems such as agglomeration and pipeline blockage when directly applied to existing polyolefin processes.

[0003] Currently, the main control method for polymer breakage during Zn catalyst application is to perform prepolymerization before the catalyst enters the main reactor. This ensures catalyst activity while improving polymer morphology and enhancing plant stability. This method is also applicable to metallocene and non-metallocene catalysts. Prepolymerization is used in most polypropylene and polyethylene processes. For example, the Hypol polypropylene process and the Horizone gas-phase polypropylene process use intermittent prepolymerization, and the prepolymerized slurry is continuously fed into the main reactor. The Spheripol polypropylene process and the ST polypropylene process use continuous prepolymerization. Compared with intermittent prepolymerization, continuous prepolymerization simplifies the operation steps, avoids the possibility of batch-to-batch catalyst quality instability caused by intermittent prepolymerization, and achieves stable plant production. CN111100227B and CN111100225B mention that adding anti-breakage agents (sulfonic acid compounds, amine compounds) to the reaction system during the catalyst pre-complexation or prepolymerization stage can further improve polymer morphology, reduce the generation of fine powder, and reduce the risk of pipeline blockage.

[0004] While continuous or intermittent prepolymerization can significantly improve the stability of the equipment and reduce the workload of subsequent fine powder separation processes, some ultra-highly active catalysts, initially highly active catalysts, or catalysts with poor particle morphology can still cause pipeline blockage during the initial contact with the monomers in the prepolymerization stage due to localized reaction hotspots and poor catalyst morphology. One solution is to reduce the continuous prepolymerization reaction temperature to control the reaction rate. However, this method reduces the prepolymerization ratio and does not effectively improve polymer morphology. Lowering the prepolymerization reaction temperature can extend the prepolymerization residence time by reducing the flow rate of inert solvents, inert gases, or monomers, thereby increasing the prepolymerization ratio. However, this reduces the flow velocity within the pipeline, potentially increasing the risk of pipeline blockage.

[0005] Therefore, new polymerization methods still need to be developed to improve or avoid pipeline blockage caused by local reaction hotspots and poor particle morphology of catalyst particles. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of pipeline blockage in existing polyolefin polymerization methods, which requires further improvement. This invention provides a method for continuous prepolymerization of polyolefin catalysts, its application, and a polyolefin polymerization method. The method provided by this invention can significantly reduce the risk of pipeline blockage and improve the operational stability of the equipment.

[0007] To achieve the above objectives, the present invention provides a method for continuous prepolymerization of polyolefin catalysts, the method comprising:

[0008] (1) The first polymerizable monomer is subjected to a first prepolymerization reaction with a metallocene catalyst composition and / or a non-metallocene catalyst composition to obtain a first prepolymerization catalyst slurry;

[0009] (2) The first prepolymerization catalyst slurry obtained in step (1) is subjected to a second prepolymerization reaction with the second polymerizing monomer to obtain the second prepolymerization catalyst slurry;

[0010] The prepolymerization ratio of the second prepolymerization reaction is 2-200 times that of the first prepolymerization reaction.

[0011] Preferably, the prepolymerization ratio of the second prepolymerization reaction is 3-80 times that of the first prepolymerization reaction.

[0012] Preferably, the temperature of the second prepolymerization reaction is 1-50°C higher than the temperature of the first prepolymerization reaction, and more preferably 5-50°C higher.

[0013] The second aspect of this invention provides an application of the continuous prepolymerization method of the polyolefin catalyst described in the first aspect in olefin polymerization.

[0014] A third aspect of the present invention provides an olefin polymerization method, the method comprising: reacting a second prepolymerization catalyst slurry obtained by the continuous prepolymerization method of the polyolefin catalyst described in the first aspect with a third polymerization monomer to obtain an olefin polymer.

[0015] The beneficial effects of this invention include:

[0016] The method provided by this invention employs a first prepolymerization reaction at a lower prepolymerization ratio and a second prepolymerization reaction at a higher prepolymerization ratio, which significantly improves the stability of the equipment operation, reduces the risk of pipeline blockage, and avoids the deactivation of some active centers caused by excessively rapid initial release of catalyst activity and high local temperatures, thereby improving the final polymerization activity of the catalyst. Simultaneously, the method provided by this invention can improve polymer morphology and reduce the content of fine powder and large agglomerates. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the olefin polymerization method provided in Embodiment 1 of the present invention;

[0018] Figure 2 This is a schematic flowchart of the olefin polymerization method provided in Embodiment 3 of the present invention.

[0019] Explanation of reference numerals in the attached figures

[0020] Figure 1 In the diagram: 01, First prepolymerization reactor; 02, Second prepolymerization reactor; 03, Main reactor; 101, Catalyst composition; 102, First material stream containing the first polymerizing monomer; 103, Coolant for the first prepolymerization reactor; 201, First prepolymerization catalyst slurry; 202, Second material stream containing the second polymerizing monomer; 203, Coolant for the second prepolymerization reactor; 301, Second prepolymerization catalyst slurry; 302, Main reactor discharge;

[0021] Figure 2 In the diagram: 11. First prepolymerization reactor; 12. Second prepolymerization reactor; 13. Main reactor; 111. Catalyst composition; 112. First material stream containing the first polymerizing monomer; 113. Coolant for the first prepolymerization reactor; 211. First prepolymerization catalyst slurry; 212. Second material stream containing the second polymerizing monomer; 213. Coolant for the second prepolymerization reactor; 311. Second prepolymerization catalyst slurry; 312. Main reactor discharge. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] As used herein, "prepolymerization" refers to a polymerization reaction carried out to achieve a lower reaction rate and monomer conversion compared to the reaction rate and monomer conversion under normal polymerization conditions. "Prepolymerization ratio" refers to the ratio of the mass of polymer produced to the mass of catalyst in the prepolymerization reactor. "Residence time" refers to the average residence time of the polyolefin catalyst in the prepolymerization reactor, expressed by the formula: reactor volume / volumetric flow rate of the prepolymer slurry exiting the reactor.

[0024] In this invention, the unit "ppm(wt)" refers to one part per million by mass, and the unit "ppm(v)" refers to one part per million by volume.

[0025] This invention provides a method for continuous prepolymerization of polyolefin catalysts, the method comprising:

[0026] (1) The first polymerizable monomer is subjected to a first prepolymerization reaction with a metallocene catalyst composition and / or a non-metallocene catalyst composition to obtain a first prepolymerization catalyst slurry;

[0027] (2) The first prepolymerization catalyst slurry obtained in step (1) is subjected to a second prepolymerization reaction with the second polymerizing monomer to obtain the second prepolymerization catalyst slurry;

[0028] The prepolymerization ratio of the second prepolymerization reaction is 2-200 times that of the first prepolymerization reaction.

[0029] The prepolymerization described in this invention refers to the contact between a polyolefin catalyst composition and a polymeric monomer at a prepolymerization reaction temperature to form a catalyst encapsulating the polyolefin.

[0030] According to the present invention, preferably, the prepolymerization ratio of the second prepolymerization reaction is 3 to 80 times that of the prepolymerization ratio of the first prepolymerization reaction, for example, 3 times, 5 times, 10 times, 15 times, 20 times, 25 times, 30 times, 35 times, 40 times, 45 times, 50 times, 55 times, 60 times, 65 times, 70 times, 75 times, 80 times, and any value within the range formed by any two of these values.

[0031] According to the present invention, preferably, the temperature of the second prepolymerization reaction is 1-50°C higher than that of the first prepolymerization reaction, more preferably 5-50°C higher, for example, 1°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, and any value within the range formed by any two of these values. This preferred embodiment can significantly improve the polymer morphology, reduce the content of fine powder and large agglomerates, improve the stability of the device operation, and reduce the risk of blockage in the conveying pipeline.

[0032] The present invention does not particularly limit the amount of the first polymerizable monomer and the metallocene catalyst composition and / or the non-metallocene catalyst composition, as long as the prepolymerization ratio of the first prepolymerization reaction is achieved. Preferably, the ratio of the mass of the first polymerizable monomer to the mass of the metallocene catalyst in the metallocene catalyst composition and / or the mass of the non-metallocene catalyst in the non-metallocene catalyst composition is greater than the prepolymerization ratio of the first prepolymerization reaction.

[0033] According to the present invention, preferably, the first polymerizing monomer and the second polymerizing monomer are each independently C2-C containing carbon-carbon double bonds and carbon-carbon triple bonds. 16 Hydrocarbon compounds, preferably C2-C 16 The olefins, more preferably selected from ethylene, propylene, 1-butene, 1-hexene, 1-octene, propadiene, 1,3-butadiene, 1,4-butadiene, 1,2-pentadiene, 1,3-pentadiene, 1,4-pentadiene, vinylcyclopentane, vinylcyclohexane, and C3-C 12 At least one of the cyclic olefins.

[0034] According to the present invention, preferably, the C3-C 12 The cycloolefin is selected from at least one of cyclobutadiene, cyclopentadiene, cyclobutene, cyclopentene, and norborneol.

[0035] In this invention, the first polymeric monomer and the second polymeric monomer can be of the same or different types. Preferably, to further reduce the risk of pipeline blockage, the first polymeric monomer and the second polymeric monomer are of different types.

[0036] When the first polymeric monomer and the second polymeric monomer are of different types, preferably, the first polymeric monomer includes a portion of the same type as the second polymeric monomer and a portion of different type.

[0037] Preferably, in the first polymeric monomer, the mass ratio of the portion that is the same type as the second polymeric monomer and the portion that is different type from the second polymeric monomer is 1-99:99-1.

[0038] According to the present invention, preferably, the C3-C 12The cycloolefin is selected from at least one of cyclobutadiene, cyclopentadiene, cyclobutene, cyclopentene, and norbornene.

[0039] According to the present invention, preferably, the conditions for the first prepolymerization reaction include: an operating temperature of -40 to 50°C, more preferably -20 to 30°C, for example -40°C, -35°C, -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, and any value within any range of any two of these values; and an operating pressure of 0.1-10 MPaG, more preferably 0.5-5 MPaG, for example 0.1 MPaG, 0.5 MPaG, 1 MPaG, 1.5 MPaG, 2 MPaG, 2.5 MPaG. The concentrations are 3 MPaG, 3.5 MPaG, 4 MPaG, 4.5 MPaG, 5 MPaG, 5.5 MPaG, 6 MPaG, 6.5 MPaG, 7 MPaG, 7.5 MPaG, 8 MPaG, 8.5 MPaG, 9 MPaG, 9.5 MPaG, 10 MPaG, and any value within the range formed by any two of these values; the residence time is ≤6 h, preferably 1-180 min, for example 1 min, 30 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, and any value within the range formed by any two of these values.

[0040] According to the present invention, preferably, the prepolymerization ratio of the first prepolymerization reaction is ≤1000 times, more preferably ≤500 times, more preferably ≤100 times, and particularly preferably 0.5-50 times, for example 0.5 times, 5 times, 10 times, 15 times, 20 times, 25 times, 30 times, 35 times, 40 times, 45 times, 50 times, and any value within the range formed by any two of these values.

[0041] According to the present invention, preferably, the conditions for the second prepolymerization reaction include: an operating temperature of -30 to 100°C, preferably -10 to 70°C; an operating pressure of 0.1-10 MPaG, preferably 0.5-5 MPaG; and a residence time of ≤2 h, preferably 1-90 min.

[0042] According to the present invention, preferably, the prepolymerization ratio of the second prepolymerization reaction is 1-3000 times, more preferably 10-1000 times, and more preferably 10-500 times, for example, 10 times, 50 times, 100 times, 150 times, 200 times, 250 times, 300 times, 350 times, 400 times, 450 times, 500 times, and any value within the range formed by any two of these values.

[0043] The present invention does not have a particular limitation on the amount of the second polymerizing monomer, as long as the prepolymerization ratio of the second prepolymerization reaction is achieved.

[0044] Preferably, the first prepolymerization reaction is carried out in a first prepolymerization reactor.

[0045] Preferably, the second prepolymerization reaction is carried out in a second prepolymerization reactor.

[0046] This invention does not specifically limit the first prepolymerization reactor and the second prepolymerization reactor. Any container that meets the above-described operating conditions for the first prepolymerization reaction can be defined as the first prepolymerization reactor, and any container that meets the above-described operating conditions for the second prepolymerization reaction can be defined as the second prepolymerization reactor. The first and second prepolymerization reactors of this invention can take various forms, including batch reactors, tubular reactors, and even pipeline reactors. These reactor types are well known to those skilled in the art.

[0047] The first prepolymerization reactor and the second prepolymerization reactor may be the same or different, and the present invention does not limit this.

[0048] This invention does not impose any particular limitation on the feeding method of each material in the first and second prepolymerization reactions. Materials can be added individually to the prepolymerization reactor or mixed in the feed pipe before being added together. To ensure a sufficient flow rate of the catalyst composition in the pipe, it is preferable to mix them in the feed pipe before adding them together to the prepolymerization reactor.

[0049] According to the present invention, preferably, the metallocene catalyst composition comprises a metallocene catalyst, a first co-catalyst, and an optional impurity remover.

[0050] The present invention does not particularly limit the type of metallocene catalyst, and can use conventional choices in the field.

[0051] Preferably, the metallocene catalyst is formed by supporting or self-supporting a metallocene compound.

[0052] Preferably, the metallocene catalyst comprises a metallocene compound with the following structure:

[0053] Non-bridged metallocene compound (Ar)₂MQ₂, Formula I;

[0054] Or a bridged metallocene compound, T(Ar)₂MQ₂, formula II;

[0055] Wherein: M is selected from Groups 3-5 of the periodic table, preferably Group 4 transition metals, and most preferably zirconium, titanium, hafnium, and vanadium transition metals;

[0056] Q is a σ ligand, preferably independently a hydrogen atom, a halogen atom, or a C1-C atom. 12 Alkoxy groups, C1-C 12 Alkyl, phenyl, or benzyl groups, and the ligand may optionally contain one or more atoms such as B, O, P, F, Cl, Si, N, Br, I;

[0057] Ar is a cyclopentadienyl group or its derivative group, which may be the same or different, and is independently selected from cyclopentadienyl group or its derivative group, indene group or its derivative group, tetrahydroindene group or its derivative group and fluorenyl group or its derivative group; and wherein Ar is optionally substituted by one or more substituents, which may optionally contain one or more B, O, P, F, Cl, Si, N, Br, I atoms. Common substituents include: hydrocarbon group, substituted hydrocarbon group, halohydro group, substituted halohydro group, silyl hydrocarbon group, substituted silyl hydrocarbon group, methylgermanyl hydrocarbon group, substituted methylgermanyl hydrocarbon group, wherein any or both of the substituents can be combined together to form a ring structure;

[0058] The T group is a substituted or unsubstituted carbon-bridged group, or a bridging group composed of carbon, silicon, germanium, tin, boron, nitrogen, or phosphorus bridging atoms, preferably a divalent bridge from -R'2C-, -R'2C-CR'2-, -R'2Si-SiR'2-, or -R'2Ge-, wherein R' is independently selected from hydrogen atoms, C1-C... 20 Hydrocarbon group, tri(C1-C) 20 Alkyl)silyl, tetra(C1-C) 20 Alkyl)silyl, penta(C1-C) 20 Alkyl)silyl, C6-C 20 Aryl, C7-C 20 Arylalkyl or C7-C 20 Alkyl aryl group. Preferred to be -CH2-, -CH2CH2-, -C(CH3)2-, -SiMe2-, -SiPh2-, -SiMePh-, -Si(CH2)3-, -Si(CH2)4-, -Si(Me3SiPh)2- or -Si(CH2)5-, etc.; and the hydrocarbon group may optionally contain one or more B, O, P, F, Cl, Si, N, Br, I atoms.

[0059] The supports for supported metallocene catalysts can be conventional choices in the art, such as silica, alumina, magnesium oxide, titanium oxide, zirconium oxide and the like, or mixtures thereof.

[0060] The first cocatalyst of this invention can convert a metallocene catalyst into an active polymerization catalyst. Preferably, the first cocatalyst is selected from at least one of alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates.

[0061] The alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates described in this invention can be selected from various alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates commonly found in the art.

[0062] The present invention does not particularly limit the amount of the first cocatalyst, and can use conventional choices in the art. Preferably, the mass ratio of the first cocatalyst to (the sum of the masses of the metallocene catalyst and the first cocatalyst) is 2-99:100, more preferably 5-70:100.

[0063] In this invention, the term "optional impurity remover" refers to the fact that an impurity remover may or may not be introduced into the metallocene catalyst composition.

[0064] The impurity remover described in this invention can be any of the impurity removers conventionally used in the art. Preferably, the impurity remover is a Group IIIA metal compound, more preferably an aluminum compound.

[0065] More preferably, the aluminum compound is selected from at least one of alkyl aluminum compounds, alkyl aluminum halides, alkoxy aluminum compounds, alkyl alkoxy aluminum compounds, and alkoxy aluminum halides.

[0066] It should be noted that when the first cocatalyst is an alkylaluminoxane compound, it can also be used as a purification agent, in which case no purification agent is added separately.

[0067] The present invention does not impose any particular limitation on the amount of the impurity removal agent, and can use conventional choices in the art. Further details of the present invention will not be elaborated upon here.

[0068] According to the present invention, the metallocene catalyst, the first co-catalyst, and the impurity remover in the metallocene catalyst composition can be added to the first prepolymerization reactor separately, or they can be mixed and added together to the first prepolymerization reactor.

[0069] In the method of the present invention, one or more of the metallocene catalyst composition may be added to the second prepolymerization reaction, or one or more of the metallocene catalyst composition may not be added. That is, at least one of the metallocene catalyst, the second cocatalyst, and the impurity remover may be added to the second prepolymerization reaction, or at least one of the metallocene catalyst, the second cocatalyst, and the impurity remover may not be added. Preferably, the method further includes adding at least one of the metallocene catalyst, the second cocatalyst, and the impurity remover to the second prepolymerization reaction.

[0070] According to the present invention, and more preferably, the method further includes adding a second co-catalyst to the second prepolymerization reaction. This preferred embodiment further enhances the polymerization activity of some metallocene catalysts without causing pipeline blockage.

[0071] Preferably, the mass ratio of the first cocatalyst to the second cocatalyst is 1:99-99:1, and more preferably 10:90-90:10.

[0072] Preferably, the second cocatalyst is selected from at least one of alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates.

[0073] The alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates described in this invention can be selected from various alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates commonly found in the art.

[0074] In this invention, the second cocatalyst and the first cocatalyst may be of the same or different types.

[0075] According to the present invention, preferably, the method includes:

[0076] (1) The first polymerization monomer, metallocene catalyst, first co-catalyst and optional impurity removal agent are subjected to a first prepolymerization reaction to obtain a first prepolymerization catalyst slurry;

[0077] (2) In the presence of a second co-catalyst, the first prepolymerization catalyst slurry obtained in step (1) is subjected to a second prepolymerization reaction with a second polymerizing monomer to obtain a second prepolymerization catalyst slurry.

[0078] The first and second cocatalysts are of different types.

[0079] The inventors have discovered that when different types of first and second cocatalysts are used, the polymerization activity of some metallocene catalysts can be further improved without causing pipeline blockage.

[0080] According to the present invention, preferably, the non-metallocene catalyst composition comprises a non-metallocene catalyst and a third co-catalyst.

[0081] In this invention, the amounts of the non-metallocene catalyst and the third co-catalyst in the non-metallocene catalyst can be conventionally selected in the art.

[0082] The present invention does not particularly limit the type of non-metallocene catalyst, and can be a conventional choice in the field.

[0083] According to the present invention, preferably, the third cocatalyst is a Group IIIA metal compound, preferably an aluminum compound and / or a boron compound.

[0084] The aluminum compound and boron compound described in this invention can be selected from various aluminum compounds and boron compounds commonly found in the art.

[0085] According to the present invention, preferably, the aluminum compound is selected from at least one of alkylaluminum compounds, modified alkylaluminum compounds, alkoxyaluminum compounds, alkylalkoxyaluminum compounds, and modified alkylaluminoxane compounds.

[0086] The present invention does not impose a particular limitation on the amount of the third cocatalyst, and can be a conventional choice in the art. Preferably, the mass ratio of the third cocatalyst to (the sum of the masses of the non-metallocene catalyst and the third cocatalyst) is 2-99:100, more preferably 5-70:100.

[0087] According to the present invention, the non-metallocene catalyst and the third co-catalyst of the non-metallocene catalyst composition can be added to the first prepolymerization reactor separately, or they can be mixed and added together to the first prepolymerization reactor.

[0088] In the method of the present invention, one or more of the non-metallocene catalyst compositions may be added to the second prepolymerization reaction, or one or more of the non-metallocene catalyst compositions may not be added. That is, at least one of the non-metallocene catalyst and the fourth co-catalyst may be added to the second prepolymerization reaction, or at least one of the non-metallocene catalyst and the fourth co-catalyst may not be added. Preferably, the method further includes adding at least one of the non-metallocene catalyst and the fourth co-catalyst to the second prepolymerization reaction.

[0089] More preferably, the method further includes adding a fourth co-catalyst to the second prepolymerization reaction. This preferred embodiment can further enhance the polymerization activity of some non-metallocene catalysts without causing pipeline blockage.

[0090] Preferably, the mass ratio of the third cocatalyst to the fourth cocatalyst is 1:99-99:1, and more preferably 10:90-90:10.

[0091] According to the present invention, preferably, the fourth cocatalyst is a Group IIIA metal compound, preferably an aluminum compound and / or a boron compound.

[0092] The aluminum compound and boron compound described in this invention can be selected from various aluminum compounds and boron compounds commonly found in the art.

[0093] According to the present invention, preferably, the aluminum compound is selected from at least one of alkylaluminum compounds, modified alkylaluminum compounds, alkoxyaluminum compounds, alkylalkoxyaluminum compounds, and modified alkylaluminoxane compounds.

[0094] In this invention, the third cocatalyst and the fourth cocatalyst may be of the same or different types.

[0095] According to the present invention, preferably, the method includes:

[0096] (1) The first polymerizing monomer, the non-metallocene catalyst and the third co-catalyst are subjected to a first prepolymerization reaction to obtain a first prepolymerization catalyst slurry;

[0097] (2) In the presence of a fourth co-catalyst, the first prepolymerization catalyst slurry obtained in step (1) is subjected to a second prepolymerization reaction with the second polymerizing monomer to obtain a second prepolymerization catalyst slurry.

[0098] The third and fourth cocatalysts are of different types.

[0099] The inventors have discovered that when different types of third and fourth cocatalysts are used, the polymerization activity of some non-metallocene catalysts can be further improved without causing pipeline blockage.

[0100] The addition of an inert solvent can, to some extent, reduce the concentration of monomers near the active site of the catalyst and inhibit the diffusion rate of monomers, thereby controlling the reaction rate. This invention allows for appropriate selection based on reaction requirements. Preferably, an inert solvent may also be added to the first prepolymerization reaction and / or the second prepolymerization reaction.

[0101] This invention allows for a wide range of choices for the inert solvent; any inert solvent that does not react with the materials involved in the first and second prepolymerization reactions can be used. Preferably, the inert solvent for the first and second prepolymerization reactions are each independently C2-C. 40 Hydrocarbon compounds, preferably C3-C 10 The hydrocarbon compound is more preferably at least one of propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, octane, heptane, decane, and aromatic hydrocarbon compounds.

[0102] The present invention does not have a particular limitation on the amount of inert solvent used, as long as the prepolymerization ratio of the first prepolymerization reaction and / or the second prepolymerization reaction is obtained.

[0103] Hydrogen can be used as a molecular weight regulator and can be selected appropriately according to the reaction requirements. Preferably, hydrogen can also be added to the first prepolymerization reaction and / or the second prepolymerization reaction.

[0104] This invention does not impose any particular limitation on the amount of hydrogen used; it can be carried out in accordance with conventional methods in the field.

[0105] The second aspect of the present invention provides an application of the continuous prepolymerization method of the polyolefin catalyst described in the first aspect in olefin polymerization, preferably in propylene polymerization.

[0106] A third aspect of the present invention provides an olefin polymerization method, the method comprising: reacting a second prepolymerization catalyst slurry obtained by the continuous prepolymerization method of the polyolefin catalyst described in the first aspect with a third polymerization monomer to obtain an olefin polymer.

[0107] The polymerization conditions described in this invention are conventional polymerization conditions in the art, and are not limited herein.

[0108] The polymerization reaction described in this invention may also incorporate an inert solvent as needed. The types of inert solvents are as described in the first aspect.

[0109] The present invention does not have a particular limitation on the amount of the inert solvent used, but rather on obtaining the prepolymerization ratio of the polymerization reaction.

[0110] The polymerization reaction described in this invention may also incorporate hydrogen gas as needed. The amount of hydrogen gas used is as described in the first aspect.

[0111] According to the present invention, preferably, the third polymerizing monomer is a C2-C monomer containing carbon-carbon double bonds and carbon-carbon triple bonds. 16 Hydrocarbon compounds, preferably C2-C 16 The olefin is more preferably selected from at least one of ethylene, propylene, 1-butene, 1-hexene, 1-octene, propadiene, 1,3-butadiene, 1,4-butadiene, 1,2-pentadiene, 1,3-pentadiene, 1,4-pentadiene, vinylcyclopentane, and vinylcyclohexane.

[0112] According to the present invention, preferably, the olefin polymer is C2-C. 16 The polyolefin preferably includes at least one of polypropylene, polyethylene, polybutene, poly(butene-hexene), poly(ethylene-butene), and poly(ethylene-hexene).

[0113] Preferably, the polymerization reaction is carried out in the main reactor.

[0114] Preferably, the main reactor is a reactor with a reaction mass load exceeding 80%. That is, the polymerization reaction occurring in the main reactor is the main reaction for olefin polymerization, and the prepolymerization reaction is an auxiliary reaction.

[0115] This invention does not specifically limit the type of the main reactor; any container that meets the above-described polymerization reaction operating conditions can be defined as the main reactor. For example, it can be a fluidized bed reactor, a tubular reactor, a batch reactor, or a multiphase multi-zone reactor.

[0116] The reaction phases in the main reactor described in this invention are various phases such as gas-solid phase, solid-liquid phase, solid-liquid-gas phase, and liquid-liquid phase.

[0117] According to a specific embodiment of the present invention, such as Figure 1 As shown, catalyst composition 101 and a first material stream 102 containing a first polymerizable monomer are injected into a first prepolymerization reactor 01 via pipelines; a second material stream 202 containing a second polymerizable monomer is mixed with the first prepolymerization catalyst slurry 201 and continuously injected into a second prepolymerization reactor 02; the second prepolymerization catalyst slurry 301 is continuously injected into a main reactor 03; the main reactor discharge 302 is sent to a subsequent reactor or other equipment. Coolant 103 in the first prepolymerization reactor and coolant 203 in the second prepolymerization reactor continuously enter and exit, providing heat for the prepolymerization reaction.

[0118] According to a specific embodiment of the present invention, such as Figure 2 As shown, catalyst composition 111 is mixed with a first material stream 112 containing a first polymerizable monomer and then injected into a first prepolymerization reactor 11 via a pipeline; a second material stream 212 containing a second polymerizable monomer and the first prepolymerization catalyst slurry 211 are injected into a second prepolymerization reactor 12 via pipelines respectively; the second prepolymerization catalyst slurry 311 is continuously injected into a main reactor 13; the main reactor discharge 312 is sent to a subsequent reactor or other equipment. Coolant 113 in the first prepolymerization reactor and coolant 213 in the second prepolymerization reactor continuously enter and exit, providing heat for the prepolymerization reaction.

[0119] In this invention, the terms "first," "second," "third," and "fourth" do not limit the substances and operations, but are only used to distinguish the substances introduced in different steps and the operations performed in different stages.

[0120] The present invention will be described in detail below through embodiments.

[0121] The polymerization activity is obtained by calculating the mass ratio of olefin polymer to polyolefin catalyst per unit time.

[0122] Polymer sieving test method: 100g sample was placed in a Frisch vibrating sieve (model: Analysette 3) with a vibration amplitude of 2.0mm and a vibration time of 15min. The weight of the sample on sieves with different aperture sizes was weighed, and the proportion of the sample in different fractions was calculated.

[0123] Example 1

[0124] Propylene polymerization according to Figure 1 The process proceeds as follows:

[0125] The propylene polymerization reaction is carried out on a 25 kg / hr bulk propylene polymerization unit, which mainly includes a first prepolymerization reactor (1 L), a second prepolymerization reactor (5 L), and a loop reactor (75 L).

[0126] (1) First prepolymerization reaction

[0127] The metallocene catalyst (prepared according to Example 1 of CN105622796B, containing the co-catalyst aluminoxane) was injected into the first prepolymerization reactor at a flow rate of 0.50 g / hr and the triisobutylaluminum (impurity remover) flow rate was 2.4 g / hr, forming a catalyst composition. The liquid propylene feed was injected into the first prepolymerization reactor at a flow rate of 1.0 kg / hr. The prepolymerization temperature of the first prepolymerization reaction was -5°C, the operating pressure was 4.0 MPaG, and the residence time was approximately 32 min.

[0128] (2) Second prepolymerization reaction

[0129] The first prepolymerization catalyst slurry is mixed with the liquid propylene feed at a flow rate of 12 kg / hr and then injected into the second prepolymerization reactor. The prepolymerization temperature of the second prepolymerization reaction is 30°C, the operating pressure is 4.0 MPaG, and the residence time is about 12 min.

[0130] (3) Polymerization reaction

[0131] The second prepolymerization catalyst slurry is continuously injected into the loop reactor. The polymerization reaction temperature is 70°C, the reaction pressure is 4 MPaG, and the total propylene feed (including the liquid propylene stream from the first and second prepolymerization reactions) in the reactor is 40 kg / hr.

[0132] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0133] Example 2

[0134] Ethylene polymerization according to Figure 1 The process proceeds as follows:

[0135] The ethylene polymerization reaction is carried out on a slurry polymerization unit, which mainly includes a first prepolymerization reactor (1L), a second prepolymerization reactor (5L), and a loop reactor (75L).

[0136] (1) First prepolymerization reaction

[0137] The metallocene catalyst (prepared according to Example 1 of CN107987192B, containing the co-catalyst aluminumoxane) was injected into the first prepolymerization reactor at a flow rate of 1.89 g / hr, the triisobutylaluminum flow rate was 1.9 g / hr, and the solvent isobutane was injected at a flow rate of 0.8 kg / hr to form a catalyst composition. The ethylene feed flow rate was 0.2 kg / hr and was continuously injected into the first prepolymerization reactor. The prepolymerization temperature of the first prepolymerization reaction was -5°C, the operating pressure was 5.0 MPaG, and the residence time was approximately 34 min.

[0138] (2) Second prepolymerization reaction

[0139] The first prepolymerization catalyst slurry is mixed with the ethylene (2 kg / hr) isobutane feed at a total flow rate of 12 kg / hr and then injected into the second prepolymerization reactor. The prepolymerization temperature of the second prepolymerization reaction is 40°C, the operating pressure is 5.0 MPaG, and the residence time is about 13 min.

[0140] (3) Polymerization reaction

[0141] The second prepolymerization catalyst slurry is continuously injected into the loop reactor. The polymerization reaction temperature is 70℃, the reaction pressure is 5.0MPaG, the ethylene feed is 26kg / hr, and the total isobutane feed (including the prepolymerization stage feed) in the reactor is 30kg / hr.

[0142] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polyethylene particles obtained.

[0143] Example 3

[0144] Propylene polymerization according to Figure 2 The process proceeds as follows:

[0145] The propylene polymerization reaction is carried out on a 25 kg / hr gas phase propylene polymerization unit, which mainly includes a first prepolymerization reactor (1 L), a second prepolymerization reactor (5 L), and a gas phase fluidized bed reactor (500 L).

[0146] (1) First prepolymerization reaction

[0147] The metallocene catalyst (prepared according to Example 1 of CN105622796B, containing the co-catalyst aluminoxane) was flowed at a rate of 0.55 g / hr, and the triisobutylaluminum catalyst was flowed at a rate of 2.4 g / hr. The catalyst composition was mixed with the liquid propylene feed at a rate of 1.0 kg / hr and then continuously injected into the first prepolymerization reactor. The prepolymerization temperature of the first prepolymerization reaction was 12 °C, the operating pressure was 2.6 MPaG, and the residence time was approximately 32 min.

[0148] (2) Second prepolymerization reaction

[0149] The first prepolymerization catalyst slurry is directly injected into the second prepolymerization reactor, and the liquid propylene feed flow rate is 12 kg / hr. The prepolymerization temperature of the second prepolymerization reaction is 30°C, the operating pressure is 2.6 MPaG, and the residence time is about 12 min.

[0150] (3) Polymerization reaction

[0151] The second prepolymerization catalyst slurry is continuously injected into the gas-phase fluidized bed reactor. The polymerization reaction temperature is 70℃, the reaction pressure is 2.6MPaG, and the total propylene feed (including the liquid propylene feed from the first and second prepolymerization reactions) in the reactor is 38kg / hr.

[0152] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0153] Example 4

[0154] Similar to Example 1, except that the first prepolymerization temperature is 26°C, the flow rate of the propylene liquid phase is 12 kg / hr, and the residence time is about 2.5 min; the second prepolymerization temperature is 30°C, and the propylene liquid phase is 1 kg / hr.

[0155] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0156] Example 5

[0157] Similar to Example 1, except that after the inert solvent (hexane) 2.0 kg / hr and the liquid propylene feed stream 1.0 kg / hr are combined, they are continuously injected into the first prepolymerization reactor, at which time the residence time is about 12 min; the second prepolymerization propylene flow rate is 10 kg / hr, and the residence time is about 12 min.

[0158] The obtained polypropylene particles were sieved, and the sieve results are shown in Table 1.

[0159] Example 6

[0160] Similar to Example 1, except that a second co-catalyst, a tri(n-butyl)ammonium tetra(m-tolyl)borate solution in hexane was added to the second prepolymerization reaction, with a co-catalyst flow rate of 0.2 g / hr.

[0161] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0162] Example 7

[0163] Similar to Example 1, except that the first monomer is composed of a liquid propylene flow rate of 0.9 kg / hr and an ethylene flow rate of 0.1 kg / hr, and is continuously injected into the first prepolymerization reactor.

[0164] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0165] Example 8

[0166] Same as Example 2, except that the catalyst is a non-amorphous catalyst (prepared according to Example 3 of CN101423574B, which already contains the co-catalyst alkylaluminoxane), and the flow rate is 1.68 g / hr.

[0167] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0168] Example 9

[0169] Similar to Example 8, except that a fourth co-catalyst, tris(pentafluorophenyl)boron, is added to the second prepolymerization reaction, with a co-catalyst flow rate of 0.2 g / hr.

[0170] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0171] Comparative Example 1

[0172] Similar to Example 1, except that the first prepolymerization reaction is not carried out, and the liquid propylene feed stream is mixed with the catalyst composition and then injected into the second prepolymerization reactor.

[0173] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0174] Comparative Example 2

[0175] Similar to Example 2, except that the first prepolymerization reaction is not carried out, and the isobutane feed stream containing ethylene (2 kg / hr) at a total flow rate of 12 kg / hr is mixed with the catalyst composition and injected into the second prepolymerization reactor.

[0176] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polyethylene particles obtained.

[0177] Comparative Example 3

[0178] Similar to Example 3, except that the first prepolymerization reaction is not carried out, the catalyst composition is directly injected into the second prepolymerization reactor, and the liquid propylene feed stream of 12 kg / hr is directly injected into the second prepolymerization reactor.

[0179] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0180] Comparative Example 4

[0181] Similar to Example 8, except that the first prepolymerization reaction is not carried out, the catalyst composition is directly injected into the second prepolymerization reactor, and the liquid propylene feed stream of 12 kg / hr is directly injected into the second prepolymerization reactor.

[0182] Table 1 shows the pipeline blockage situation after the reaction of the present invention has been running continuously for 3 days, as well as the sieving results of the polypropylene particles obtained.

[0183]

[0184] As can be seen from the results in Table 1, the method of the present invention can effectively reduce the risk of pipeline blockage, significantly improve the stability of equipment operation, and enhance polymerization activity. Simultaneously, the method of the present invention can reduce the content of fine polymer powder (sieving particle size < 71 μm) and the content of large-diameter particles with agglomeration (sieving particle size > 2 mm), resulting in a narrower polymer particle size distribution.

[0185] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for continuous prepolymerization of polyolefin catalysts, characterized in that, The method includes: (1) The first polymerizable monomer is subjected to a first prepolymerization reaction with a metallocene catalyst composition and / or a non-metallocene catalyst composition to obtain a first prepolymerization catalyst slurry; (2) The first prepolymerization catalyst slurry obtained in step (1) is subjected to a second prepolymerization reaction with the second polymerizing monomer to obtain the second prepolymerization catalyst slurry; The prepolymerization ratio of the second prepolymerization reaction is 3-80 times that of the first prepolymerization reaction; The temperature of the second prepolymerization reaction is 10-50°C higher than that of the first prepolymerization reaction.

2. The method according to claim 1, wherein, the first and second polymerizable monomers are each independently a C2-C20 hydrocarbon compound containing a carbon-carbon double bond, a carbon-carbon triple bond, or a combination thereof. 16 at least one of the hydrocarbon compounds.

3. The method according to claim 2, wherein, The first and second polymerized monomers are each independently at least one of C2-C 16 olefins.

4. The method according to claim 3, wherein, The first and second polymerization monomers are each independently selected from ethylene, propylene, 1-butene, 1-hexene, 1-octene, propadiene, 1,3-butadiene, 1,4-butadiene, 1,2-pentadiene, 1,3-pentadiene, 1,4-pentadiene, vinylcyclopentane, vinylcyclohexane, and C3-C 12 At least one of the cyclic olefins.

5. The method according to any one of claims 1-4, wherein, The conditions for the first prepolymerization reaction include: operating temperature of -40 to 50°C; operating pressure of 0.1 to 10 MPaG; and residence time of ≤6 h.

6. The method according to claim 5, wherein, The conditions for the first prepolymerization reaction include: operating temperature of -20 to 30°C; operating pressure of 0.5 to 5 MPaG; and residence time of 1 to 180 min.

7. The method according to any one of claims 1-4, wherein, The prepolymerization ratio of the first prepolymerization reaction is ≤1000 times.

8. The method according to claim 7, wherein, The prepolymerization ratio of the first prepolymerization reaction is ≤100 times.

9. The method according to claim 8, wherein, The prepolymerization ratio of the first prepolymerization reaction is 0.5-50 times.

10. The method according to any one of claims 1-4, wherein, The conditions for the second prepolymerization reaction include: operating temperature of -30 to 100°C; operating pressure of 0.1 to 10 MPaG; and residence time of ≤2 h.

11. The method according to claim 10, wherein, The conditions for the second prepolymerization reaction include: operating temperature of -10 to 70°C; operating pressure of 0.5 to 5 MPaG; and residence time of 1 to 90 min.

12. The method according to any one of claims 1-4, wherein, The prepolymerization ratio of the second prepolymerization reaction is 1-3000 times.

13. The method according to claim 12, wherein, The prepolymerization ratio of the second prepolymerization reaction is 10-1000 times.

14. The method according to claim 13, wherein, The prepolymerization ratio of the second prepolymerization reaction is 10-500 times.

15. The method according to any one of claims 1-4, wherein, The metallocene catalyst composition comprises a metallocene catalyst, a first co-catalyst, and an optional impurity remover.

16. The method according to claim 15, wherein, The first cocatalyst is selected from at least one of alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates.

17. The method according to claim 15, wherein, The impurity remover is a Group IIIA metal compound.

18. The method according to claim 16, wherein, The first cocatalyst is an aluminum compound.

19. The method according to claim 18, wherein, The aluminum compound is selected from at least one of alkylaluminum compounds, alkylaluminum halides, alkoxyaluminum compounds, alkylalkoxyaluminum compounds, and alkoxyaluminum halides.

20. The method of claim 15, wherein, The method also includes adding a second co-catalyst to the second prepolymerization reaction.

21. The method according to claim 20, wherein, The mass ratio of the first cocatalyst to the second cocatalyst is 1:99-99:

1.

22. The method according to claim 21, wherein, The mass ratio of the first cocatalyst to the second cocatalyst is 10:90-90:

10.

23. The method of claim 20, wherein, The second cocatalyst is selected from at least one of alkylaluminoxane compounds, organoboron compounds, ionic compounds, and borates.

24. The method of claim 20, wherein, The method includes: (1) The first polymerization monomer, metallocene catalyst, first co-catalyst and optional impurity removal agent are subjected to a first prepolymerization reaction to obtain a first prepolymerization catalyst slurry; (2) In the presence of the second co-catalyst, the first prepolymerization catalyst slurry obtained in step (1) is subjected to a second prepolymerization reaction with the second polymerizing monomer to obtain the second prepolymerization catalyst slurry; The first and second cocatalysts are of different types.

25. The method according to any one of claims 1-4, wherein, The non-metallocene catalyst composition comprises a non-metallocene catalyst and a third co-catalyst.

26. The method of claim 25, wherein, The third cocatalyst is a Group IIIA metal compound.

27. The method according to claim 26, wherein, The third cocatalyst is an aluminum compound and / or a boron compound.

28. The method according to claim 25, wherein, The method also includes adding a fourth co-catalyst to the second prepolymerization reaction.

29. The method according to claim 28, wherein, The mass ratio of the third cocatalyst to the fourth cocatalyst is 1:99-99:

1.

30. The method according to claim 29, wherein, The mass ratio of the third cocatalyst to the fourth cocatalyst is 10:90-90:

10.

31. The method according to claim 28, wherein, The fourth cocatalyst is a Group IIIA metal compound.

32. The method according to claim 31, wherein, The fourth cocatalyst is an aluminum compound and / or a boron compound.

33. The method according to claim 28, wherein, The method includes: (1) The first polymerization monomer, the non-metallocene catalyst and the third co-catalyst are subjected to a first prepolymerization reaction to obtain a first prepolymerization catalyst slurry; (2) In the presence of the fourth co-catalyst, the first prepolymerization catalyst slurry obtained in step (1) is subjected to a second prepolymerization reaction with the second polymerizing monomer to obtain the second prepolymerization catalyst slurry; The third and fourth cocatalysts are of different types.

34. The application of the continuous prepolymerization method of the polyolefin catalyst according to any one of claims 1-33 in olefin polymerization.

35. The application according to claim 34, wherein the continuous prepolymerization method of the polyolefin catalyst is used in propylene polymerization.

36. A method for olefin polymerization, characterized in that, The method includes: reacting a second prepolymerized catalyst slurry obtained by a continuous prepolymerization method of the polyolefin catalyst according to any one of claims 1-33 with a third polymerizing monomer to obtain an olefin polymer.

37. The method of claim 36, wherein, The third monomer is a C2-C monomer containing carbon-carbon double and triple bonds. 16 At least one of the hydrocarbon compounds.

38. The method according to claim 37, wherein, The third monomer is C2-C. 16 At least one of the olefins.

39. The method according to claim 38, wherein, The third polymerization monomer is selected from at least one of ethylene, propylene, 1-butene, 1-hexene, 1-octene, propadiene, 1,3-butadiene, 1,4-butadiene, 1,2-pentadiene, 1,3-pentadiene, 1,4-pentadiene, vinylcyclopentane, and vinylcyclohexane.

40. The method of claim 36, wherein, The olefin polymer is C2-C. 16 At least one of the polyolefins.

41. The method according to claim 40, wherein, The olefin polymer includes at least one of polypropylene, polyethylene, polybutene, poly(butene-hexene), poly(ethylene-butene), and poly(ethylene-hexene).

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