A polyolefin catalyst and its preparation method and application

Abstract

The present invention discloses a polyolefin catalyst and its preparation method and application. The polyolefin catalyst comprises a mixture and / or reaction product of the following components: a mesoporous material, a magnesium compound and / or a titanium compound, an organic solvent and a halogenating agent; wherein the mesoporous material is a silicon-based mesoporous material with a two-dimensional hexagonal pore structure, an average pore diameter of 4-15 nm, a specific surface area of ​​550-650 m 2 / g, a pore volume of 0.5-1.5 mL / g, and an average particle size of 0.5-15 μm; the titanium compound is selected from the formula Ti(OR 2 ) n X 2 4‑n One or more of the compounds shown, wherein R 2 Selected from C2~C 20 Hydrocarbon or C3~C 20 Cyclic hydrocarbon group, X 2 The catalyst is selected from halogen, 0<n≤4. The catalyst of the present invention has high catalytic activity when used for ethylene homopolymerization or copolymerization, and the molecular weight distribution of the polyolefin product is narrow and the melt index is excellent.

Description

Technical Field

[0001] The present invention belongs to the field of ethylene polymerization, and in particular relates to a polyolefin catalyst and a preparation method and application thereof. Background Art

[0002] Currently, there are several main methods for preparing olefin polymerization catalysts: (1) The loading method, in which the active center is loaded onto a preformed inorganic inert carrier such as magnesium chloride, silica gel, alumina, etc., can produce catalysts with uniform particles and good particle morphology, but the catalyst activity is relatively low. (2) The dissolution-precipitation method, in which a magnesium compound or a magnesium compound complex is dissolved and then reprecipitated, and certain formation conditions are controlled to prepare a spherical Ti-MgCl2 catalyst.

[0003] Chinese patents CN1158136A, CN1958620A, CN1229092A, CN1299375A, CN1795213A, and U.S. patents US3787384A, US4148754A, US4173547A, and US4508843A involve methods in which the resulting catalyst particles have less than ideal morphology, a wide or even multimodal distribution, and are not conducive to the long-term stable operation of the polymerization device.

[0004] In patent CN1229092A, since organic substances such as phthalic anhydride are used as precipitation aids to promote the precipitation of precipitates during the synthesis of the catalyst, and a large amount of titanium tetrachloride needs to be added, not only does the presence of the anhydride have an adverse effect on the catalyst, but the use of a large amount of titanium tetrachloride also causes waste and pollution. In addition, the system is prone to stickiness, making the catalyst difficult to prepare.

[0005] Chinese patent CN1958620A uses magnesium chloride as a carrier and titanium tetrachloride as an active component. The catalyst preparation method is as follows: MgCl2 is first dissolved in a solvent system to form a uniform, transparent solution, which is then reacted with TiCl4 at low temperature in the presence of a silicone ester compound, and a solid catalyst is precipitated by slowly increasing the temperature. The resulting catalyst component exhibits high catalytic activity when used in ethylene polymerization. However, due to the suboptimal polymer particle morphology, particularly the unsatisfactory flowability of the resulting polymer powder, it still cannot fully meet the requirements of industrial production for the production of certain resin grades that require high polymer powder flowability.

[0006] Catalysts are prepared by spray-drying an inorganic substance with a very small average particle size, such as silica gel, along with the active components of the catalyst. Patents such as US Pat. Nos. 7,276,566, 7,160,833, 6,982,237, 6,806,221, and CN 1,085,915A disclose a method for preparing a Ziegler-Natta catalyst system. In tetrahydrofuran, titanium tetrachloride is reduced with magnesium metal to produce a TiCl3 tetrahydrofuran solution. Magnesium chloride is then dissolved in the tetrahydrofuran. The two solutions are thoroughly mixed, unreacted magnesium and undissolved magnesium chloride are filtered out, and the filtered solution is thoroughly mixed with silica gel before being spray-dried to obtain dispersed catalyst particles. These catalysts are highly active and have a high titanium content. However, this preparation method requires a filtration step, resulting in a large amount of waste residue and increased post-processing steps and costs. Summary of the Invention

[0007] To overcome the shortcomings of existing polyolefin catalyst preparation processes, such as limitations due to factors such as the carrier pore structure and the solubility of the active components, resulting in low effective loading of the active components on the carrier, and thus poor catalytic activity of supported polyolefin catalysts prepared from existing supported polyolefin catalyst carriers, a method for preparing a polyolefin catalyst, a polyolefin catalyst prepared by the method, the use of the polyolefin catalyst prepared by the method in olefin monomer polymerization reactions, and the polyolefins produced by the method are provided. The catalyst of the present invention exhibits high catalytic activity when used in ethylene homopolymerization or copolymerization, and the polyolefin product has a narrow molecular weight distribution and an excellent melt index. The present invention does not require the use of large amounts of titanium tetrachloride, the system is non-sticky, and no post-processing steps are required, making it environmentally friendly. The resulting catalyst particles are spherical in shape.

[0008] One of the objects of the present invention is to provide a polyolefin catalyst comprising a mixture and / or reaction product of the following components: (1) a mesoporous material, (2) a magnesium compound and / or a titanium compound, (3) an organic solvent, and (4) a halogenating agent, wherein the mesoporous material is a silicon-based mesoporous material having a two-dimensional hexagonal pore structure and an average pore diameter of 4-15 nm, for example, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm or 15 nm.

[0009] In the present invention, the mesoporous material has a unique two-dimensional hexagonal pore structure. This well-ordered long-range structure enables the mesoporous material to exhibit high strength over a wide temperature range and under a wide range of strains. Furthermore, the unique two-dimensional hexagonal pore structure of the mesoporous material, combined with its narrow pore size distribution and uniform pore distribution, facilitates good dispersion of the metal components on the carrier surface. This allows the resulting polyolefin catalyst to possess the advantages of a supported catalyst, such as good dispersibility of the magnesium and / or titanium active components, high loading, few side reactions, and simple post-processing, while also exhibiting strong catalytic activity and high stability. This ensures that the supported catalyst prepared using the mesoporous material as a support exhibits better catalytic activity in olefin monomer polymerization reactions, significantly improving the conversion rate of the reaction raw materials.

[0010] In a preferred embodiment, the specific surface area of ​​the mesoporous material is 550-650 m 2 / g, a pore volume of 0.5-1.5 mL / g, an average particle size of 0.5-15 μm, for example, a specific surface area of ​​550, 560, 570, 580, 590, 600, 610, 620, 630, 640 or 650 m 2 / g, a pore volume of 0.5, 0.6, 0.8, 1, 1.2, 1.4 or 1.5 mL / g, and an average particle size of 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm or 15 μm.

[0011] Among them, the mesoporous material with the above characteristics is not easy to agglomerate, and the supported catalyst prepared by using it as a carrier can improve the conversion rate of the reaction raw materials in the olefin polymerization process. Specifically, when the specific surface area of ​​the mesoporous material is less than 550m 2 / g and / or pore volume is less than 0.5mL / g, the catalytic activity of the supported catalyst prepared by using it as a carrier will be significantly reduced; when the specific surface area of ​​the mesoporous material is greater than 650m 2 / g and / or the pore volume is greater than 1.5mL / g, the supported catalyst prepared by using it as a carrier is prone to agglomeration during the olefin polymerization reaction, thereby affecting the conversion rate of the olefin monomer in the olefin polymerization reaction.

[0012] In a preferred embodiment, the average pore size of the mesoporous material is 4-12 nm, and the specific surface area is 580-620 m 2 / g, the pore volume is 0.5-1mL / g, and the average particle size is 0.8-10μm.

[0013] For example, the average pore size of the mesoporous material is 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm and 12 nm, and any average pore size between any two average pore sizes; the specific surface area is 580 m 2 / g、590m 2 / g、600m 2 / g、610m 2 / g or 620m 2 / g; the pore volume is 0.5, 0.6, 0.7, 0.8, 0.9 or 1 mL / g; the average particle size is 0.8, 0.85, 0.9, 0.95 or 10 μm; this can ensure that the mesoporous material has the advantages of larger pore size, larger pore volume and larger specific surface area, which is more conducive to the good dispersion of magnesium and / or titanium active components on the surface of the mesoporous material, and further ensure that the polyolefin catalyst prepared therefrom has excellent catalytic performance, thereby obtaining beneficial effects such as high olefin monomer conversion rate and good polymer particle morphology, narrow molecular weight distribution, and excellent fluidity.

[0014] In a preferred embodiment, the magnesium compound is selected from the formula Mg(OR 1 ) m X 1 2-m One or more of the compounds shown, wherein R 1 Selected from C2~C 20 Hydrocarbon or C3~C 20 Cyclic hydrocarbon group, X 1 Selected from halogen, 0≤m≤2.

[0015] Among them, the C2~C 20 The hydrocarbon group is a saturated or unsaturated, straight chain or branched hydrocarbon group, and the C3 to C 20 The cyclic hydrocarbon group is a saturated or unsaturated cyclic hydrocarbon group.

[0016] In a further preferred embodiment, in the formula Mg(OR 1 ) m X 1 2-m In, R 1 C2~C 10 The alkyl group, X 1 is the chlorine element, 0≤m≤2.

[0017] In a further preferred embodiment, the magnesium compound is at least one selected from diethoxymagnesium, dipropoxymagnesium, dibutoxymagnesium, dioctyloxymagnesium, and magnesium dichloride, such as magnesium dichloride.

[0018] In a preferred embodiment, the titanium compound is selected from the formula Ti(OR2 ) n X 2 4-n One or more of the compounds shown, wherein R 2 Selected from C2~C 20 Hydrocarbon or C3~C 20 Cyclic hydrocarbon group, X 2 Selected from halogen, 0<n≤4;

[0019] Among them, C2~C 20 The hydrocarbon group is a saturated or unsaturated straight chain or branched hydrocarbon group, C3~C 20 The cyclic hydrocarbon group is a saturated or unsaturated cyclic hydrocarbon group.

[0020] In a further preferred embodiment, in the formula Ti(OR 2 ) n X 2 4-n In, R 2 C2~C 10 The alkyl group, X 2 It is the chlorine element, 0<n≤4.

[0021] In a further preferred embodiment, the titanium compound is selected from at least one of tetrabutyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, and tetra-tert-butyl titanate, for example, selected from at least one of tetraethyl titanate, tetrabutyl titanate, and tetraisopropyl titanate.

[0022] In a preferred embodiment, the organic solvent is an electron donor solvent, and the electron donor solvent is at least one selected from the group consisting of alkyl esters of aliphatic carboxylic acids, alkyl esters of aromatic carboxylic acids, aliphatic ethers, and cyclic ethers.

[0023] In a further preferred embodiment, the organic solvent is selected from at least one of C1-C4 saturated aliphatic carboxylic acid alkyl esters, C7-C8 aromatic carboxylic acid alkyl esters, C2-C6 aliphatic ethers, and C3-C4 cyclic ethers.

[0024] In a further preferred embodiment, the organic solvent is selected from at least one of methyl formate, ethyl acetate, butyl acetate, diethyl ether, hexyl ether and tetrahydrofuran (THF), such as tetrahydrofuran.

[0025] In a preferred embodiment, the halogenating agent is selected from R 3 a MX 3 b At least one of the compounds shown, wherein M is selected from aluminum or silicon, X 3 Selected from halogen, R 3 Selected from C2~C 20 Hydrocarbon, C2~C20 Hydrocarbyloxy, C3~C 20 Cyclic hydrocarbon groups, C3~C 20 Cycloalkyloxy, C6~C 20 One of the aromatic groups of , a=0, 1, 2 or 3, b=1, 2, 3 or 4.

[0026] In a further preferred embodiment, the halogenating agent is selected from R 3 A SiCl 4-A 、R 3 B AlCl 3-B At least one of the following, wherein R 3 Selected from C2~C 20 Hydrocarbon, C2~C 20 Hydrocarbyloxy, C3~C 20 Cyclic hydrocarbon groups, C3~C 20 Cycloalkyloxy, C6~C 20 One of the aromatic groups, 0≤A<4, 0≤B<3;

[0027] In a further preferred embodiment, the halogenating agent is preferably at least one selected from ethylaluminum dichloride, diethylaluminum monochloride, isobutylaluminum dichloride, diisobutylaluminum monochloride, isopropylaluminum dichloride, diisopropylaluminum monochloride, and silicon tetrachloride.

[0028] In a preferred embodiment, based on each mole of magnesium in the magnesium compound, the amount of the titanium compound is 0.1 to 20 moles, the amount of the organic solvent is 0.01 to 100 moles, and the amount of the halogenating agent is 0.1 to 50 moles.

[0029] In a further preferred embodiment, based on each mole of magnesium in the magnesium compound, the amount of the titanium compound is 0.1 to 5.0 moles, the amount of the organic solvent is 5 to 80 moles, and the amount of the halogenating agent is 0.1 to 10 moles.

[0030] In a further preferred embodiment, based on each mole of magnesium in the magnesium compound, the amount of the titanium compound is 0.1 to 3.0 moles, the amount of the organic solvent is 15 to 60 moles, and the amount of the halogenating agent is 0.1 to 5 moles.

[0031] For example, based on each mole of magnesium in the magnesium compound, the amount of the titanium compound is 0.1, 0.5, 1, 1.5, 2, 2.5 or 3 moles, the amount of the organic solvent is 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 moles, and the amount of the halogenating agent is 0.1, 0.2, 0.5, 0.8, 1, 2, 3, 4 or 5 moles.

[0032] In a preferred embodiment, the weight of the inorganic oxide support is 1-50 g, preferably 2-20 g, based on each gram of magnesium in the magnesium compound, for example, 1 g, 2 g, 3 g, 4 g, 5 g, 6 g, 7 g, 8 g, 9 g, 10 g, 12 g, 14 g, 16 g, 18 g, 20 g, 25 g, 30 g, 35 g, 40 g, 45 g or 50 g.

[0033] In a preferred embodiment, based on 100 wt% of the total weight of the polyolefin catalyst, the content of magnesium and / or titanium is 1 to 30 wt%, preferably 1 to 20 wt%.

[0034] For example, based on the total weight of the polyolefin catalyst as 100wt%, the content of magnesium and / or titanium is 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt% or 30wt%.

[0035] In a preferred embodiment, the components further optionally contain an organic epoxy compound.

[0036] In a further preferred embodiment, the organic epoxy compound is selected from one or more of alkylene oxides, halogen-substituted alkylene oxides, olefin-substituted alkylene oxides, diene diepoxides, and glycidyl ethers.

[0037] In a further preferred embodiment, the organic epoxy compound is selected from one or more of ethylene oxide, propylene oxide, butylene oxide, butadiene monoepoxide, butadiene diepoxide, epichlorohydrin, methyl glycidyl ether, and diglycidyl ether, for example, one or more of epichlorohydrin and methyl glycidyl ether.

[0038] Most preferably, the amount of the organic epoxy compound used is 0.1 to 10 moles, preferably 0.1 to 5.0 moles, more preferably 0.1 to 3.0 moles, for example 0.1, 0.5, 1, 1.5, 2, 2.5 or 3 moles per mole of magnesium in the magnesium compound.

[0039] In a preferred embodiment, the average pore size of the polyolefin catalyst is 4-15 nm, and the specific surface area is 520-600 m 2 / g, the pore volume is 0.6-1.4mL / g, the average particle size is 1-20μm, and the particle size distribution value is 1.7-1.8.

[0040] For example, the average pore size of the polyolefin catalyst is 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 nm, and the specific surface area is 520, 530, 540, 550, 560, 570, 580, 590 or 600 m 2 / g, the pore volume is 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or 1.4 mL / g, the average particle size is 1, 2, 4, 6, 8, 10, 12, 14, 16, 18 or 20 μm, and the particle size distribution value is 1.7, 1.75 or 1.8.

[0041] In the present invention, the content of each element in the polyolefin catalyst can be measured by X-ray fluorescence spectrometry; the average particle size of the mesoporous material is measured by a laser particle size distribution analyzer, and the specific surface area, pore volume and average pore size are measured according to the nitrogen adsorption method; the particle size refers to the particle size of the raw material particles. When the raw material particles are spheres, the particle size is expressed by the diameter of the sphere; when the raw material particles are cubes, the particle size is expressed by the side length of the cube; when the raw material particles are irregular in shape, the particle size is expressed by the mesh size of the sieve that can just screen out the raw material particles.

[0042] A second object of the present invention is to provide a method for preparing a polyolefin catalyst, preferably for preparing the polyolefin catalyst described in one of the objects of the present invention, the preparation method comprising:

[0043] (1) mixing the magnesium compound and / or titanium compound, the organic solvent and the optional organic epoxy compound to react to obtain a precursor solution;

[0044] (2) mixing the precursor solution with the mesoporous material to obtain a suspension;

[0045] (3) adding a halogenating agent to the suspension to obtain a slurry to be sprayed through reaction;

[0046] (4) spray drying to obtain the polyolefin catalyst.

[0047] In the present invention, the mesoporous material as a carrier to load components such as magnesium and / or titanium can be used in an impregnation mixing reaction manner. The capillary pressure of the pore structure of the mesoporous material allows the components such as magnesium and / or titanium to enter the pores of the mesoporous material. At the same time, the components such as magnesium and / or titanium are also adsorbed on the surface of the mesoporous material until the components such as magnesium and / or titanium reach adsorption equilibrium on the surface of the carrier. In the present invention, the impregnation is carried out under a protective gas. The protective gas is a gas that does not react with the raw materials and products. For example, it can be nitrogen conventional in the art or at least one of the gases of the zeroth group of the periodic table, preferably nitrogen.

[0048] In a preferred embodiment, based on each mole of magnesium in the magnesium compound, the amount of the titanium compound is 0.1 to 20 moles, the amount of the organic epoxy compound is 0.1 to 10 moles, the amount of the organic solvent is 0.01 to 100 moles, and the amount of the halogenating agent is 0.1 to 50 moles.

[0049] In a further preferred embodiment, based on each mole of magnesium in the magnesium compound, the amount of the titanium compound is 0.1 to 5.0 moles, the amount of the organic epoxy compound is 0.1 to 5.0 moles, the amount of the organic solvent is 5 to 80 moles, and the amount of the halogenating agent is 0.1 to 10 moles.

[0050] In a further preferred embodiment, based on each mole of magnesium in the magnesium compound, the amount of the titanium compound is 0.1 to 3.0 moles, the amount of the organic epoxy compound is 0.1 to 3.0 moles, the amount of the organic solvent is 15 to 60 moles, and the amount of the halogenating agent is 0.1 to 5 moles.

[0051] In a preferred embodiment, the reaction temperature in step (1) is 25 to 100° C., preferably 40 to 80° C.; more preferably, the reaction is carried out until a transparent solution is obtained, for example, for 1 to 20 hours, preferably 2 to 10 hours.

[0052] Wherein, step (1) is carried out at 25-100°C, preferably 40-80°C, until a transparent solution is obtained. For example, the reaction temperature in step (1) is 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C.

[0053] In a further preferred embodiment, step (1) is carried out as follows: in the presence of a protective gas, the organic solvent is added to a reactor equipped with stirring, the reactor temperature is controlled to 25-40°C, the magnesium compound and / or titanium compound and the optional epoxy compound are rapidly added when stirring is turned on, and the system temperature is adjusted to 60-75°C for constant temperature reaction for 1-5 hours until a transparent solution is formed.

[0054] In the present invention, the magnesium compound and the titanium compound can be mixed together in step (1) and then mixed and impregnated with the mesoporous material, or they can be mixed and impregnated separately. That is, the impregnation treatment can be a co-impregnation treatment or a step-by-step impregnation treatment. In order to save preparation costs and simplify the experimental process, the impregnation treatment is preferably a co-impregnation treatment.

[0055] In a preferred embodiment, the mesoporous material is a silicon-based mesoporous material having a two-dimensional hexagonal pore structure.

[0056] In a further preferred embodiment, the average pore size of the mesoporous material is 4-15 nm, the specific surface area is 550-650 m 2 / g, pore volume of 0.5-1.5mL / g, and average particle size of 0.5-15μm.

[0057] In a further preferred embodiment, the average pore size of the mesoporous material is 4-12 nm, and the specific surface area is 580-620 m 2 / g, the pore volume is 0.5-1mL / g, and the average particle size is 0.8-10μm.

[0058] In a preferred embodiment, step (2) is carried out at 0-100°C for 0.5-10 hours, preferably, at 0-80°C (preferably 60-75°C) for 0.5-4 hours.

[0059] For example, step (2) is carried out at 0°C, 10°C, 20°C, 25°C, 30°C, 40°C, 50°C, 60°C, 65°C, 70°C, 75°C, 80°C, 90°C or 100°C (e.g., room temperature) for 0.1 hour, 0.2 hour, 0.3 hour, 0.4 hour, 0.5 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0060] In order to make the reaction more complete and the active center loading more uniform, step (2) is preferably carried out under stirring conditions.

[0061] In a preferred embodiment, in step (3), the reaction temperature is 0 to 80° C., preferably 20 to 70° C. (e.g., room temperature); and / or the reaction time is 1 min to 10 h, preferably 0.5 to 5 h.

[0062] For example, in step (3), the reaction temperature is 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C; and / or the reaction time is 1 min, 10 min, 30 min, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h.

[0063] Among them, in this step, the chlorination reaction or chlorination reduction reaction of the magnesium-titanium complex is completed, that is, the chlorine element replaces the alkoxy group in the magnesium-titanium complex. At the same time, different halogenating agents can also reduce the valence state of the titanium compound to a lower valence state. The halogenation reaction usually controls the kettle temperature so as not to cause local overheating of the reaction. Stirring is usually performed during the addition process to facilitate the smooth progress of the reaction.

[0064] In a preferred embodiment, the spray drying in step (4) can be carried out according to a conventional method, preferably but not limited to at least one selected from pressure spray drying, centrifugal spray drying and airflow spray drying; preferably, the spray drying adopts airflow spray drying; more preferably, the spray drying is carried out in an atomizer.

[0065] In a preferred embodiment, the spray drying conditions include: carrying out under a protective atmosphere, an air inlet temperature of 100-150°C, an air outlet temperature of 90-120°C, and a carrier gas flow rate of 10-50 L / s; for example, the air inlet temperature is 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, the air outlet temperature is 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, and the carrier gas flow rate is 10 L / s, 20 L / s, 30 L / s, 40 L / s or 50 L / s.

[0066] The above conditions can impart a relatively high viscosity to the spraying material, making it suitable for spray forming operations, and also impart good mechanical strength to the particles obtained by spraying.

[0067] Preferably, the spray drying conditions are such that the particle size of the prepared polyolefin catalyst is 1-20 μm and the particle size distribution value is 1.7-1.8.

[0068] In the present invention, the mesoporous material is preferably obtained by the following method:

[0069] (a) in the presence of a template, a silicon source is contacted with an acid for reaction, followed by crystallization, filtration, and drying to obtain a mesoporous material precursor;

[0070] (b) subjecting the mesoporous material precursor to a template removal treatment, a heat activation treatment, and a ball milling treatment in sequence to obtain the mesoporous material.

[0071] In a preferred embodiment, the type of the template is not particularly limited, as long as the obtained mesoporous material precursor has a two-dimensional hexagonal pore structure. Preferably, the template can be a triblock copolymer of polyoxyethylene-polyoxypropylene-polyoxyethylene. The template can be commercially available (for example, it can be purchased from Aldrich under the trade name P123, with a molecular formula of EO 20 PO 70 EO 20 ), can also be prepared by various existing methods. When the template is polyoxyethylene-polyoxypropylene-polyoxyethylene, the molar number of the template is calculated based on the average molecular weight of polyoxyethylene-polyoxypropylene-polyoxyethylene.

[0072] In a preferred embodiment, the acid can be various acidic aqueous solutions commonly used in the art, for example, an aqueous solution of at least one selected from hydrochloric acid, sulfuric acid, nitric acid and hydrobromic acid, preferably an aqueous solution of hydrochloric acid.

[0073] In a further preferred embodiment, the amount of the acid used is not particularly limited and can vary within a wide range. Preferably, the contact is performed at a pH value of 1-6.

[0074] In a further preferred embodiment, in step (a), the contacting conditions include: temperature of 25-60°C, time of more than 25 minutes, and pH of 1-6. To facilitate uniform mixing of the substances, the mixing contact is preferably carried out under stirring.

[0075] For example, the contact conditions include: a temperature of 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, a time of more than 25 minutes, and a pH of 1, 2, 3, 4, 5 or 6.

[0076] In a preferred embodiment, the amount of the template and the silicon source can vary within a wide range, for example, the molar ratio of the template to the silicon source can be 1:(10-90); preferably 1:(50-75).

[0077] For example, the molar ratio of the template to the silicon source can be 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80 or 1:90.

[0078] In a preferred embodiment, the silicon source can be various silicon sources commonly used in the art, preferably the silicon source is at least one of ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, sodium orthosilicate and silica sol, more preferably ethyl orthosilicate.

[0079] According to a preferred embodiment of the present invention, the process of mixing and contacting the silicon source with the acid agent in the presence of a template comprises: adding the template triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene P123 to an aqueous solution of hydrochloric acid, with a molar feed ratio of triblock copolymer polyoxyethylene-polyoxyisobutylene-polyoxyethylene P123: water: hydrochloric acid = 1:9000-15000:100-500, stirring at a temperature of 25-60°C until dissolved, and then adding silicon source tetraethyl orthosilicate to the above-mentioned solution, with the molar feed ratio of triblock copolymer polyoxyethylene-polyoxyisobutylene-polyoxyethylene P123: tetraethyl orthosilicate = 1:(50-75), and stirring at a temperature of 25-60°C for more than 25 minutes.

[0080] In a preferred embodiment, in step (a), the crystallization conditions include: temperature of 90-180° C. and time of 10-40 h.

[0081] For example, the crystallization conditions include: a temperature of 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, and a time of 10h, 15h, 20h, 25h, 30h, 35h or 40h; wherein the crystallization is carried out by a hydrothermal crystallization method.

[0082] In order to ensure that a mesoporous molecular sieve material with a sufficiently large pore size can be obtained, the crystallization condition is further preferably a temperature of 130-180°C.

[0083] In a preferred embodiment, in step (a), the filtration process may include: after filtration, repeatedly washing with water (preferably deionized water) (the number of washings may be 2-10), and then performing suction filtration.

[0084] In a preferred embodiment, in step (a), the drying can be carried out in a drying oven, and the drying conditions may include: a temperature of 110-150° C. and a time of 3-6 hours.

[0085] For example, the drying conditions may include a temperature of 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C, and a time of 3 hours, 4 hours, 5 hours or 6 hours.

[0086] In a preferred embodiment, in step (b), the template removal treatment adopts an alcohol washing method.

[0087] In a further preferred embodiment, in step (b), the alcohol washing conditions include: washing temperature of 90-120° C., and washing time of 10-40 h.

[0088] For example, the alcohol washing conditions include: a washing temperature of 90° C., 95° C., 100° C., 110° C., 115° C., or 120° C., and a washing time of 10 h, 20 h, 30 h, or 40 h.

[0089] In a preferred embodiment, in step (b), in order to remove the hydroxyl groups and residual moisture of the mesoporous material, a thermal activation treatment is required before the mesoporous material is loaded with the metal component. The conditions of the thermal activation treatment include: calcining the mesoporous material at a temperature of 300-900°C for 7-10 hours in the presence of nitrogen.

[0090] For example, the conditions of the thermal activation treatment include: calcining the mesoporous material at a temperature of 300°C, 400°C, 500°C, 600°C, 700°C, 800°C or 900°C for 7h, 7.5h, 8h, 8.5h, 9h, 9.5h or 10h in the presence of nitrogen.

[0091] According to the present invention, in step (b), the specific operation method and conditions of the ball milling treatment are based on not destroying or substantially destroying the pore structure of the mesoporous material having a two-dimensional hexagonal structure. Those skilled in the art can select various appropriate conditions according to the above principles to implement the present invention.

[0092] In a preferred embodiment, the ball milling treatment can be carried out in a ball mill, wherein the diameter of the grinding balls in the ball mill is 2-3 mm; preferably, the number of grinding balls can be reasonably selected according to the size of the ball mill jar, and for a ball mill jar with a size of 50-150 mL, 20-80 grinding balls can usually be used; more preferably, the material of the grinding balls is selected from agate and / or polytetrafluoroethylene, preferably agate.

[0093] In a further preferred embodiment, the ball milling treatment conditions include: a rotation speed of the grinding balls of 300-500 r / min, a temperature in the ball milling jar of 15-100° C., and a ball milling time of 0.1-100 hours.

[0094] For example, the ball milling conditions include: a grinding ball rotation speed of 300, 350, 400, 450 or 500 r / min, a temperature in the ball mill jar of 15°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C, and a ball milling time of 0.1, 0.5, 1, 2, 3, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 hours.

[0095] Preferably, in step (b), the ball milling treatment is performed under conditions such that the average particle diameter of the mesoporous material obtained by ball milling is 0.5-10 μm.

[0096] While conducting research on the preparation of polyolefins by polymerization of olefin monomers, the inventors discovered that the carrier used in the present invention has a high specific surface area due to its special two-dimensional hexagonal pore structure and large pore size, which can effectively increase the loading amount of the active component. In addition, the use of ball milling and spray drying technology makes the resulting slurry more delicate, thereby improving the monodispersity of the particle size distribution and catalytic activity of the resulting polyolefin catalyst. As a result, the polyolefin catalyst exhibits high polymerization activity when used in olefin polymerization reactions, and the molecular weight distribution and melt index of the resulting polyolefin product are further improved. The resulting polyolefin product is spherical and has uniform particle size.

[0097] Furthermore, the method for preparing a polyolefin catalyst provided by the present invention can directly produce spherical polyolefin catalysts in a single step through a spray drying process, which is simple to operate. The resulting spherical polyolefin catalyst particles have a stable structure, high strength, and are not easily broken. They also have a uniform and narrow particle size distribution. This effectively controls the moisture content of the particles, prevents catalyst agglomeration during use, and improves their fluidity, facilitating the storage, transportation, post-processing, and application of the resulting polyolefin catalyst.

[0098] The polyolefin catalyst prepared using the method of the present invention has a spherical morphology, a higher loading of magnesium and / or titanium components, and a more rational pore structure. When used for olefin monomer polymerization, it exhibits higher polymerization activity, and the resulting polymer particles have good morphology, a narrow molecular weight distribution, and excellent fluidity. The polymerization process can be gas-phase, slurry, or solution polymerization.

[0099] The third object of the present invention is to provide a polyolefin catalyst obtained by the preparation method described in the second object of the present invention.

[0100] A fourth object of the present invention is to provide a polyolefin catalyst composition comprising the polyolefin catalyst described in the first or third object of the present invention and an alkyl aluminum compound.

[0101] In a preferred embodiment, the alkyl aluminum compound is selected from the formula AlR q X (3-q) At least one of the compounds shown, wherein R is selected from one of hydrogen and C1-C5 hydrocarbon groups, X is selected from halogen (such as chlorine), and q is selected from an integer of 1-3.

[0102] Preferably, the C1-C5 hydrocarbon group may be one or more of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl and neopentyl.

[0103] In a further preferred embodiment, specific examples of the alkylaluminum compound include, but are not limited to, trimethylaluminum, dimethylaluminum chloride, triethylaluminum, diethylaluminum chloride, tri-n-propylaluminum, di-n-propylaluminum chloride, tri-n-butylaluminum, tri-sec-butylaluminum, tri-tert-butylaluminum, di-n-butylaluminum chloride, and diisobutylaluminum chloride. Most preferably, the alkylaluminum compound is triethylaluminum.

[0104] In a further preferred embodiment, the molar ratio of the aluminum in the alkyl aluminum compound to the titanium in the catalyst is the aluminum-titanium ratio commonly used in catalysts in the art, preferably 20 to 500, more preferably 30 to 300, for example 20, 30, 50, 80, 100, 150, 200, 250, 300, 400 or 500.

[0105] A fifth object of the present invention is to provide the use of the polyolefin catalyst described in the first object of the present invention, the polyolefin catalyst obtained by the preparation method described in the second object of the present invention, or the polyolefin catalyst composition described in the fourth object of the present invention in olefin polymerization, especially in ethylene homopolymerization or copolymerization of ethylene and other α-olefins.

[0106] The polymerization reaction conditions are not particularly limited and may be the olefin polymerization conditions commonly used in the art.

[0107] In a preferred embodiment, the other α-olefin may be at least one of propylene, 1-butene, 1-hexene, 1-octene, 1-pentene, and 4-methyl-1-pentene.

[0108] According to the present invention, there is no particular limitation on the reaction conditions for polymerization, and the reaction conditions may be conventional olefin polymerization reaction conditions in the art. For example, the reaction may be carried out in the presence of a protective gas, and the polymerization conditions may include: a temperature of 10-100°C, a time of 0.5-5h, and a pressure of 0.1-2MPa; preferably, the polymerization conditions may include: a temperature of 20-95°C, a time of 1-4h, and a pressure of 0.5-1.5MPa; further preferably, the temperature is 70-90°C, the time is 1-2h, and the pressure is 1-1.5MPa.

[0109] In the present invention, the polymerization reaction may be carried out in the presence of a solvent. The solvent used in the polymerization reaction is not particularly limited, and may be, for example, hexane.

[0110] Preferably, the polymerization method may further include filtering and separating the final reaction mixture after the polymerization reaction is completed, thereby obtaining polyolefin particle powder.

[0111] The endpoints and any values ​​of the ranges disclosed in the present invention 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 each range, the endpoint values ​​of each range and a separate point value, and the separate point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0112] Compared with the prior art, the present invention has the following beneficial effects: it does not require the use of a large amount of titanium tetrachloride, the system is non-sticky, the obtained catalyst particles are spherical in shape, the catalyst particles have low adhesion, the preparation process does not require a filtration step, the preparation process is easy to implement, and it is environmentally friendly. When used for ethylene homopolymerization or copolymerization, it has high catalytic activity, the prepared polymer powder has good fluidity, the powder obtained by polymerization has a high bulk density, and the prepared polymer has a narrow molecular weight distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0113] Figure 1 This is a SEM scanning electron microscope image of the micromorphology of the polyolefin catalyst prepared in Example 1. DETAILED DESCRIPTION

[0114] The present invention will be described in detail below with reference to specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0115] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0116] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the scope of protection of the present invention.

[0117] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0118] In the following examples and comparative examples, the triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene was purchased from Aldrich Company, abbreviated as P123, and has a molecular formula of EO 20 PO 70 EO 20 , the substance with the registration number 9003-11-6 in the American Chemical Abstracts Directory and an average molecular weight Mn of 5800.

[0119] In the following examples and comparative examples, X-ray diffraction analysis was carried out on an X-ray diffractometer of model D8Advance purchased from Bruker AXS, Germany; scanning electron microscopy analysis was carried out on a scanning electron microscope of model XL-30 purchased from FEI, USA; pore structure parameter analysis was carried out on an ASAP2020-M+C adsorption instrument purchased from Micromeritics, USA, and the specific surface area and pore volume of the samples were calculated using the BET method; the particle size distribution SPAN value of the sample was determined on a Malvern laser particle size analyzer; the rotary evaporator was produced by IKA, Germany, model RV10 digital; the loading amount of each component of the polyolefin catalyst was determined on a wavelength dispersive X-ray fluorescence spectrometer of model Axios-Advanced purchased from PANalytical, the Netherlands; and spray drying was carried out on a B-290 spray dryer purchased from Buchi, Switzerland.

[0120] The molecular weight distribution (Mw / Mn) of the polyolefin powder was measured using a PL-GPC220 gel permeation chromatograph produced by Polymer Laboratories Ltd., UK, according to the method specified in ASTM D6474-99.

[0121] The melt index of polyolefins is measured using the method specified in ASTM D1238-99.

[0122] [Example 1]

[0123] This example is used to illustrate a polyolefin catalyst and a preparation method thereof.

[0124] (1) Preparation of carrier

[0125] 4 g (0.0007 mol) of template P123 was added to a solution containing 37 wt% hydrochloric acid (16.4 mL) and water (128 mL), and stirred at 40°C until P123 was completely dissolved; 8.86 g (0.042 mol) of tetraethyl orthosilicate was then added to the above solution, stirred at 40°C for 24 h, and then the obtained solution was transferred to a polytetrafluoroethylene-lined reactor, crystallized at 150°C for 24 h, then filtered and washed with deionized water 4 times, and then filtered and dried to obtain a mesoporous material precursor; the mesoporous material precursor was washed with ethanol under reflux conditions for 24 h to remove the template to obtain mesoporous molecular sieve A1; the product from which the template was removed was then calcined at 400°C for 10 h under nitrogen protection for thermal activation treatment to remove the hydroxyl groups and residual moisture of the mesoporous material to obtain the thermally activated mesoporous material B1;

[0126] Take 10g of the above-mentioned heat-activated mesoporous material B1 and put it into a 100ml ball mill, wherein the ball mill is made of polytetrafluoroethylene, the grinding balls are made of agate, the diameter of the grinding balls is 3-15mm, the number is 30, the rotation speed is 400r / min, the ball mill is closed, and the temperature in the ball mill is 25℃ for 20h to obtain 10g of mesoporous material C1, the average particle diameter of the mesoporous material is 1-5μm.

[0127] (2) Preparation of polyolefin catalyst

[0128] To a reactor equipped with a stirring device, which had been purged and maintained under a N2 atmosphere, was added 130 mL of tetrahydrofuran (electron donor solvent). The reactor temperature was controlled at 30°C. While stirring was on, 4.5 g of magnesium dichloride, 3.1 g of tetrabutyl titanate, and 0.8 g of epichlorohydrin were rapidly added. The system temperature was adjusted to 70°C and the reaction was continued for 4 hours to obtain a transparent solution. The solution was cooled to 50°C and then mixed with 5.6 g of mesoporous material C1. The reaction was stirred for 2 hours, followed by the addition of 12.8 ml of a 30 wt% ethylaluminum dichloride hexane solution. The reaction was continued for 1 hour to obtain a uniform concentration of the spray slurry. The resulting spray slurry was then introduced into a spray dryer. Under N2 protection, the spray dryer air inlet temperature was controlled at 140°C, the air outlet temperature was 105°C, and the carrier gas flow rate was 30 L / s. Spray drying was performed to obtain polyolefin catalyst Cat-1.

[0129] The mesoporous material C1 and polyolefin catalyst Cat-1 were characterized by XRD, scanning electron microscopy, particle size analyzer and nitrogen adsorption analyzer.

[0130] X-ray fluorescence analysis revealed that the catalyst Cat-1 obtained in this example had a magnesium content of 8.85% by weight and a titanium content of 2.26% by weight, calculated as elements.

[0131] The mesoporous molecular sieve A1 was subjected to X-ray diffraction detection. From the XRD spectrum, it can be clearly seen that the mesoporous molecular sieve A1 has a diffraction peak in the small angle area, indicating that the mesoporous molecular sieve A1 has a two-dimensional ordered hexagonal pore structure unique to the mesoporous material SBA-15;

[0132] Figure 1 This is a SEM scanning electron microscope image of the microscopic morphology of the polyolefin catalyst Cat-1. As can be seen from the image, the microscopic morphology of the polyolefin catalyst Cat-1 is spherical and the particle size is at the micron level, which helps the device to operate smoothly.

[0133] Table 1 shows the pore structure parameters of mesoporous material C1 and polyolefin catalyst Cat-1.

[0134] Table 1

[0135]

[0136] It can be seen from the data in Table 1 that after the mesoporous material C1 is loaded with the magnesium component and the titanium component, the specific surface area and the pore volume are reduced, which indicates that the magnesium component and the titanium component enter the interior of the mesoporous material C1 during the loading reaction.

[0137] [Example 2]

[0138] This example is used to illustrate the polyolefin catalyst and the preparation method thereof of the present invention.

[0139] (1) Preparation of carrier

[0140] 4 g (0.0007 mol) of template P123 was added to a solution containing 37 wt% hydrochloric acid (16.4 mL) and water (128 mL), and stirred at 40° C. until P123 was completely dissolved; 10.9 g (0.0525 mol) of tetraethyl orthosilicate was then added to the above solution, stirred at 40° C. for 24 h, and then the obtained solution was transferred to a polytetrafluoroethylene-lined reactor, crystallized at 180° C. for 20 h, then filtered and washed with deionized water 4 times, and then filtered and dried to obtain a mesoporous material precursor; the mesoporous material precursor was washed with ethanol under reflux conditions for 24 h to remove the template to obtain a mesoporous molecular sieve material A2; the product from which the template was removed was then calcined at 500° C. for 10 h under nitrogen protection for thermal activation treatment to remove the hydroxyl groups and residual moisture of the mesoporous material to obtain a thermally activated mesoporous material B2;

[0141] 10g of the heat-activated mesoporous material B2 was placed in a 100ml ball mill made of polytetrafluoroethylene (PTFE) with 30 agate balls (3-15mm in diameter) at a speed of 300 rpm. The mill was sealed and milled at 30°C for 16 hours to yield 10g of mesoporous material C2 with an average particle diameter of 0.9-7μm.

[0142] (2) Preparation of polyolefin catalyst

[0143] The catalyst preparation steps were the same as those in Example 1, except that the spray dryer air inlet temperature was controlled at 140° C., the air outlet temperature was controlled at 105° C., the carrier gas flow rate was 40 L / s, and spray drying was performed to obtain polyolefin catalyst Cat-2.

[0144] The mesoporous material C2 and polyolefin catalyst Cat-2 were characterized by XRD, scanning electron microscopy, particle size analyzer and nitrogen adsorption analyzer.

[0145] X-ray fluorescence analysis revealed that the catalyst Cat-2 obtained in this example had a magnesium content of 8.53% by weight and a titanium content of 2.58% by weight, calculated as elements.

[0146] Table 2 shows the pore structure parameters of mesoporous material C2 and polyolefin catalyst Cat-2.

[0147] Table 2

[0148]

[0149] It can be seen from the data in Table 2 that after the mesoporous material C2 is loaded with the magnesium component and the titanium component, the specific surface area and the pore volume are reduced, which indicates that the magnesium component and the titanium component enter the interior of the mesoporous material C2 during the loading reaction.

[0150] [Example 3]

[0151] This example is used to illustrate the polyolefin catalyst and the preparation method thereof of the present invention.

[0152] (1) Preparation of carrier

[0153] 4 g (0.0007 mol) of template P123 was added to a solution containing 37 wt% hydrochloric acid (16.4 mL) and water (128 mL), and stirred at 40°C until P123 was completely dissolved; 7.27 g (0.035 mol) of tetraethyl orthosilicate was then added to the above solution and stirred at 50°C for 20 h. The resulting solution was then transferred to a polytetrafluoroethylene-lined reactor and crystallized at 175°C for 22 h. The mixture was then filtered and washed with deionized water four times, then filtered and dried to obtain a mesoporous material precursor; the mesoporous material precursor was washed with ethanol under reflux for 24 h to remove the template to obtain a mesoporous molecular sieve material A3; the product from which the template was removed was then calcined at 700°C for 8 h under nitrogen protection for thermal activation to remove the hydroxyl groups and residual moisture of the mesoporous material to obtain a thermally activated mesoporous material B3;

[0154] Take 10g of the above-mentioned heat-activated mesoporous material B3 and put it into a 100ml ball mill, where the ball mill is made of polytetrafluoroethylene, the grinding balls are made of agate, the diameter of the grinding balls is 3-15mm, the number is 30, the rotation speed is 550r / min, the ball mill is closed, and the temperature in the ball mill is 20℃ for 12h to obtain 10g of mesoporous material C3 with an average particle diameter of 1-9μm.

[0155] (2) Preparation of polyolefin catalyst

[0156] The catalyst preparation steps were the same as those in Example 1, except that the amount of tetrahydrofuran was adjusted from 130 ml to 110 ml, and spray drying was performed to obtain polyolefin catalyst Cat-3.

[0157] The mesoporous material C3 and polyolefin catalyst Cat-3 were characterized by XRD, scanning electron microscopy, particle size analyzer and nitrogen adsorption analyzer.

[0158] X-ray fluorescence analysis revealed that the catalyst Cat-3 obtained in this example had a magnesium content of 8.89% by weight and a titanium content of 2.65% by weight, calculated as elements.

[0159] Table 3 shows the pore structure parameters of mesoporous material C3 and polyolefin catalyst Cat-3.

[0160] Table 3

[0161]

[0162] It can be seen from the data in Table 3 that after the mesoporous material C3 is loaded with the magnesium component and the titanium component, the specific surface area and the pore volume are reduced, which indicates that the magnesium component and the titanium component enter the interior of the mesoporous material C3 during the loading reaction.

[0163] [Example 4]

[0164] This example is used to illustrate the polyolefin catalyst and the preparation method thereof of the present invention.

[0165] Polyolefin catalyst Cat-4 was prepared according to the method of Example 1, except that the amount of tetrahydrofuran was adjusted from 130 ml to 120 ml, and the halogenating agent was replaced by 5 ml of silicon tetrachloride instead of 12.8 ml of 30% ethylaluminum dichloride solution. Spray drying was performed to obtain polyolefin catalyst Cat-4.

[0166] The mesoporous material C4 and polyolefin catalyst Cat-4 were characterized by XRD, scanning electron microscopy and nitrogen adsorption.

[0167] X-ray fluorescence analysis revealed that the catalyst Cat-4 obtained in this example had a magnesium content of 8.94% by weight and a titanium content of 2.22% by weight, calculated as elements.

[0168] Table 4 shows the pore structure parameters of mesoporous material C4 and polyolefin catalyst Cat-4.

[0169] Table 4

[0170]

[0171] It can be seen from the data in Table 4 that after the active component is loaded on the mesoporous material C4, the specific surface area and pore volume are reduced, which indicates that the magnesium component enters the interior of the mesoporous material C4 during the loading reaction.

[0172] [Example 5]

[0173] The polyolefin catalyst Cat-5 was prepared according to the method of Example 1, except that the tetrabutyl titanate in the polyolefin catalyst preparation step was adjusted from 3.1 g to 5.1 g.

[0174] Table 5 shows the pore structure parameters of mesoporous material C1 and polyolefin catalyst Cat-5.

[0175] Table 5

[0176]

[0177] It can be seen from the data in Table 5 that after the active component is loaded on the mesoporous material C1, the specific surface area and pore volume are reduced, which indicates that the magnesium component enters the interior of the mesoporous material C1 during the loading reaction.

[0178] [Example 6]

[0179] Polyolefin catalyst Cat-6 was prepared according to the method of Example 1, except that the epichlorohydrin in the polyolefin catalyst preparation step was adjusted from 0.8 g to 1.2 g.

[0180] Table 6 shows the pore structure parameters of mesoporous material C1 and polyolefin catalyst Cat-6.

[0181] Table 6

[0182]

[0183] It can be seen from the data in Table 6 that after the active component is loaded on the mesoporous material C1, the specific surface area and pore volume are reduced, which indicates that the magnesium component enters the interior of the mesoporous material C1 during the loading reaction.

[0184] [Example 7]

[0185] The catalyst component was prepared according to the method of Example 1, except that 12.8 ml of 30 wt% ethylaluminum dichloride hexane solution in the polyolefin catalyst preparation step was changed to 22 ml.

[0186] Table 7 shows the pore structure parameters of mesoporous material C1 and polyolefin catalyst Cat-7.

[0187] Table 7

[0188]

[0189] It can be seen from the data in Table 7 that after the active component is loaded on the mesoporous material C1, the specific surface area and pore volume are reduced, which indicates that the magnesium component enters the interior of the mesoporous material C1 during the loading reaction.

[0190] [Example 8]

[0191] The catalyst components were prepared according to the method of Example 1, except that the polyolefin catalyst was prepared in the following steps: 130 mL of tetrahydrofuran (electron donor solvent) was added to a reactor equipped with a stirring device and maintained under N2 purging. The reactor temperature was controlled at 30°C. While stirring was on, 4.5 g of magnesium dichloride, 3.1 g of tetrabutyl titanate, and 0.8 g of epichlorohydrin were rapidly added. The system temperature was adjusted to 65°C and the reaction was continued until a transparent solution was obtained. The solution was cooled to 45°C and mixed with 5.6 g of mesoporous material C1. The reaction was stirred for 2 hours, and then 12.8 ml of a 30 wt% ethylaluminum dichloride hexane solution was added. The reaction was continued for 1 hour to obtain a uniform concentration of the spray slurry. The spray slurry was then introduced into a spray dryer. Under N2 protection, the spray dryer air inlet temperature was controlled at 140°C, the air outlet temperature was controlled at 101°C, and the carrier gas flow rate was controlled at 30 L / s. The polyolefin catalyst Cat-8 was spray-dried.

[0192] Table 8 shows the pore structure parameters of mesoporous material C1 and polyolefin catalyst Cat-8.

[0193] Table 8

[0194]

[0195] It can be seen from the data in Table 8 that after the active component is loaded on the mesoporous material C1, the specific surface area and pore volume are reduced, which indicates that the magnesium component enters the interior of the mesoporous material C1 during the loading reaction.

[0196] [Comparative Example 1]

[0197] This comparative example is used to illustrate a reference polyolefin catalyst and its preparation method.

[0198] (1) Preparation of carrier

[0199] Commercially available silica gel (TS610 manufactured by Cabot Corporation, with a particle size of 0.02-0.1 μm) was used as carrier D1. The silica gel carrier D1 was calcined at 400° C. for 10 h under nitrogen protection to remove hydroxyl groups and residual moisture, thereby obtaining a heat-activated silica gel carrier E1.

[0200] (2) Preparation of polyolefin catalyst

[0201] A polyolefin catalyst was prepared according to the method of Example 1, except that the same weight portion of the activated silica gel carrier E1 was used instead of the mesoporous material C1, thereby preparing a comparative catalyst Cat-D-1.

[0202] In the catalyst Cat-D-1 obtained in this example, the content of magnesium element is 8.80 wt % and the content of titanium element is 2.36 wt %, calculated as elements.

[0203] [Comparative Example 2]

[0204] This comparative example is used to illustrate a reference polyolefin catalyst and its preparation method.

[0205] The polyolefin catalyst Cat-D-2 was prepared according to the method of Example 1, except that the same weight of alumina carrier was used instead of the mesoporous material C1, thereby preparing carrier D2 and polyolefin catalyst Cat-D-2, respectively.

[0206] X-ray fluorescence analysis revealed that the catalyst Cat-D-2 obtained in this example had a magnesium content of 8.75% by weight and a titanium content of 2.16% by weight, calculated as elements.

[0207] [Comparative Example 3]

[0208] This comparative example is used to illustrate a reference polyolefin catalyst and its preparation method.

[0209] The polyolefin catalyst Cat-D-3 was prepared according to the method of Example 1, except that in step (2), 140 mL of tetrahydrofuran was added to a reactor equipped with a stirring device that was purged with N2 and maintained in an N2 atmosphere. The reactor temperature was controlled to 40°C. When stirring was turned on, 4.5 g of magnesium dichloride and 1.0 mL of titanium tetrachloride were quickly added. The system temperature was adjusted to 70°C and the reaction was carried out at a constant temperature for 4 hours to obtain a solution containing magnesium dichloride and titanium tetrachloride. At 40°C, 5.6 g of mesoporous material C3 was added to the solution containing magnesium dichloride and titanium tetrachloride, and the reaction was stirred for 2 hours to obtain a slurry to be sprayed with uniform concentration. The obtained slurry to be sprayed was then introduced into a spray dryer. Under N2 protection, the spray dryer air inlet temperature was controlled to 140°C, the air outlet temperature was controlled to 105°C, the carrier gas flow rate was 30 L / s, and the polyolefin catalyst Cat-D-3 was spray dried.

[0210] X-ray fluorescence analysis revealed that the catalyst Cat-D-3 obtained in this example contained 8.9% by weight of magnesium and 2.35% by weight of titanium, calculated as elements.

[0211] [Comparative Example 4]

[0212] The polyolefin catalyst Cat-D-4 was prepared according to the method of Example 1, except that 9.1 mmol of titanium tetrachloride was used to replace the ethylaluminum dichloride solution, and other conditions remained unchanged, to obtain Cat-D-4.

[0213] X-ray fluorescence analysis revealed that the catalyst Cat-D-4 obtained in this example had a magnesium content of 8.85% by weight and a titanium content of 2.36% by weight, calculated as elements.

[0214] [Comparative Example 5]

[0215] Polyolefin catalyst Cat-D-5 was prepared according to the method of Example 1, except that 47.3 mmol of ethylene glycol monobutyl ether was further added in the polyolefin catalyst preparation step. Other conditions remained unchanged to obtain Cat-D-5.

[0216] X-ray fluorescence analysis revealed that the catalyst Cat-D-5 obtained in this example had a magnesium content of 8.87% by weight and a titanium content of 2.26% by weight, calculated as elements.

[0217] [Experimental Example 1]

[0218] This example is used to illustrate the method for preparing polyethylene by polymerizing ethylene using the polyolefin catalyst of the present invention.

[0219] In a 2L stainless steel high-pressure polymerization reactor, the atmosphere was replaced with nitrogen and ethylene three times each, 1L hexane, 1mmol triethylaluminum and 20-50mg catalyst Cat-1 were added to the 2L stainless steel stirring reactor, and then the temperature was raised to 75°C, hydrogen was added at 0.18MPa, and after the hydrogenation was completed, ethylene was added at 0.75MPa, and the temperature was raised to 85°C for polymerization. After the reaction for 2 hours, the addition of ethylene was stopped, the temperature was lowered, the pressure was released, the polyethylene powder was weighed, the catalyst activity was calculated, and the molecular weight distribution (Mw / Mn) and melt index MI of the polyethylene powder were tested. 2.16 The polymerization activities of the catalysts are listed in Table 9.

[0220] [Experimental Example 2-8]

[0221] Ethylene was polymerized to prepare polyethylene according to the method of Experimental Example 1, except that polyolefin catalysts Cat-2 to Cat-8 were used instead of polyolefin catalyst Cat-1. The molecular weight distribution (Mw / Mn) and melt index (MI) of the obtained polyethylene granules were 2.16 The polymerization activities of the catalysts are listed in Table 9.

[0222] [Comparative Experimental Examples 1-5]

[0223] Ethylene was polymerized to prepare polyethylene according to the method of Experimental Example 1, except that polyolefin catalysts Cat-D-1 to Cat-D-5 were used instead of polyolefin catalyst Cat-1. The molecular weight distribution (Mw / Mn) and melt index (MI) of the obtained polyethylene granules were 2.16 The polymerization activities of the catalysts are listed in Table 9.

[0224] Table 9

[0225]

[0226]

[0227] It can be seen from the results in Table 9 that the polyolefin catalyst prepared by the method of the present invention using the mesoporous material loaded with titanium component and / or magnesium component has high catalytic activity, and the polymer particles obtained when used to catalyze ethylene polymerization have good morphology and excellent fluidity. The melt index of the polymer powder is large and the molecular weight distribution of the polymer powder is narrow.

[0228] The storage, transportation, post-processing and application of the obtained polyolefin catalyst are facilitated. In addition, the method of the present invention can be used to prepare a supported catalyst, and a spherical polyolefin catalyst can be directly obtained in one step by spray drying, which is easy to operate.

[0229] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A polyolefin catalyst comprising a mixture and / or reaction product of the following components: (1) a mesoporous material, (2) a magnesium compound and / or a titanium compound, (3) an organic solvent, (4) a halogenating agent, and (5) an organic epoxy compound; wherein the mesoporous material is a silicon-based mesoporous material having a two-dimensional hexagonal pore structure, and the average pore size thereof is 4-15 nm; the organic solvent is an electron donor solvent, and the electron donor solvent is selected from at least one of an alkyl ester of an aliphatic carboxylic acid, an alkyl ester of an aromatic carboxylic acid, an aliphatic ether, and a cyclic ether; the specific surface area of ​​the mesoporous material is 550-650 m 2 / g, pore volume of 0.5-1.5mL / g, and average particle size of 0.5-15μm.

2. The polyolefin catalyst according to claim 1, characterized in that The magnesium compound is selected from the formula Mg(OR 1 ) m X 1 2-m One or more of the compounds shown, wherein R 1 Selected from C2~C 20 Hydrocarbon or C3~C 20 Cyclic hydrocarbon group, X 1 is selected from halogen, 0≤m≤2; and / or, The titanium compound is selected from the formula Ti(OR 2 ) n X 2 4-n One or more of the compounds shown, wherein R 2 Selected from C2~C 20 Hydrocarbon or C3~C 20 Cyclic hydrocarbon group, X 2 is selected from halogen, 0<n≤4; and / or, The halogenating agent is selected from R 3 a MX 3 b At least one of the compounds shown, wherein M is selected from aluminum or silicon, X 3 Selected from halogen, R 3 Selected from C2~C 20 Hydrocarbon, C2~C 20 Hydroxyl, C3~C 20 Cyclic hydrocarbon groups, C3~C 20 Cycloalkyloxy, C6~C 20 One of the aromatic groups of , a=0, 1, 2 or 3, b=1, 2, 3 or 4.

3. The polyolefin catalyst according to claim 2, characterized in that The magnesium compound is selected from the formula Mg(OR 1 ) m X 1 2-m One or more of the compounds shown, wherein R 1 C2~C 10 The alkyl group, X 1 is chlorine, 0≤m≤2; and / or, The titanium compound is selected from the formula Ti(OR 2 ) n X 2 4-n One or more of the compounds shown, wherein R 2 C2~C 10 The alkyl group, X 2 It is the chlorine element, 0<n≤4.

4. The polyolefin catalyst according to claim 1, characterized in that The titanium compound is used in an amount of 0.1 to 20 moles per mole of magnesium in the magnesium compound, and / or the organic solvent is used in an amount of 0.01 to 100 moles, and / or the halogenating agent is used in an amount of 0.1 to 50 moles; and / or, Based on gram of magnesium element in the magnesium compound, the weight of the mesoporous material carrier is 1-50 g.

5. The polyolefin catalyst according to claim 4, characterized in that Based on gram of magnesium element in the magnesium compound, the weight of the mesoporous material carrier is 2-20 g.

6. The polyolefin catalyst according to any one of claims 1 to 5, characterized in that The organic epoxy compound is selected from one or more of alkylene oxides, halogen-substituted alkylene oxides, olefin-substituted alkylene oxides, diene diepoxides, and glycidyl ethers.

7. The polyolefin catalyst according to claim 6, characterized in that The amount of the organic epoxy compound used is 0.1 to 10 moles per mole of magnesium in the magnesium compound.

8. The polyolefin catalyst according to claim 6, characterized in that The average pore size of the polyolefin catalyst is 4-15 nm, and the specific surface area is 520-600 m 2 / g, the pore volume is 0.6-1.4mL / g, the average particle size is 1-20μm, and the particle size distribution value is 1.7-1.

8.

9. A method for preparing a polyolefin catalyst, for preparing the polyolefin catalyst according to any one of claims 1 to 8, the method comprising: (1) mixing the magnesium compound and / or titanium compound, the organic solvent and the organic epoxy compound, and reacting them to obtain a precursor solution; (2) mixing the precursor solution with the mesoporous material to obtain a suspension; (3) adding a halogenating agent to the suspension to obtain a slurry to be sprayed through reaction; (4) spray drying to obtain the polyolefin catalyst.

10. The preparation method according to claim 9, characterized in that The reaction temperature in step (1) is 25-100°C; and / or, Step (2) is carried out at 0-100°C for 0.5-10 hours; and / or, In step (3), the reaction temperature is 0-80° C.; and / or the reaction time is 1 min-10 h.

11. The preparation method according to claim 10, characterized in that: The reaction in step (1) is carried out at a temperature of 40-80°C; and / or, Step (2) is carried out at 0-80°C for 0.5-4 hours; and / or, In step (3), the reaction temperature is 20-70° C.; and / or the reaction time is 0.5-5 h.

12. The preparation method according to claim 9, characterized in that The spray drying is selected from at least one of pressure spray drying, centrifugal spray drying and air flow spray drying.

13. The preparation method according to claim 12, characterized in that The spray drying conditions include: carrying out the spray drying under a protective atmosphere, an air inlet temperature of 100-150° C., an air outlet temperature of 90-120° C., and a carrier gas flow rate of 10-50 L / s.

14. The preparation method according to any one of claims 9 to 13, characterized in that: The mesoporous material is obtained by the following method: (a) in the presence of a template, a silicon source is contacted with an acid for reaction, followed by crystallization, filtration, and drying to obtain a mesoporous material precursor; (b) The mesoporous material precursor is sequentially subjected to a template removal treatment, a heat activation treatment, and a ball milling treatment to obtain the mesoporous material.

15. The preparation method according to claim 14, characterized in that The template may be a triblock copolymer of polyoxyethylene-polyoxypropylene-polyoxyethylene; and / or, The acid is an aqueous solution of at least one selected from hydrochloric acid, sulfuric acid, nitric acid and hydrobromic acid; and / or, The silicon source is at least one of ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, sodium orthosilicate and silica sol; and / or, The molar ratio of the template to the silicon source is 1:(10-90).

16. The preparation method according to claim 14, characterized in that The molar ratio of the template to the silicon source is 1:(50-75).

17. The preparation method according to claim 15, characterized in that In step (a), the contact conditions include: temperature of 25-60°C, time of more than 25 minutes, pH of 1-6; and / or, In step (a), the crystallization conditions include: temperature of 90-180° C., time of 10-40 h; and / or, In step (a), the filtration process may include: after filtration, repeatedly washing with water, and then performing suction filtration; and / or, In step (a), the drying conditions may include: a temperature of 110-150° C. and a time of 3-6 hours; and / or, In step (b), the template removal treatment is performed by alcohol washing; and / or, In step (b), the conditions of the thermal activation treatment include: calcining the mesoporous material at a temperature of 300-900° C. for 7-10 h in the presence of nitrogen; and / or, In step (b), the ball milling treatment conditions include: a rotation speed of the grinding balls of 300-500 r / min, a temperature in the ball milling jar of 15-100° C., and a ball milling time of 0.1-100 hours.

18. The preparation method according to claim 17, characterized in that: In step (b), the alcohol washing conditions include: washing temperature of 90-120° C., and washing time of 10-40 hours.

19. A polyolefin catalyst obtained by the preparation method according to any one of claims 10 to 18.

20. A polyolefin catalyst composition comprising the polyolefin catalyst according to any one of claims 1 to 9 or obtained by the preparation method according to any one of claims 10 to 18 and an alkyl aluminum compound.

21. The polyolefin catalyst composition according to claim 20, characterized in that The alkyl aluminum compound is selected from the formula AlR q X (3-q) At least one of the compounds shown, wherein R is selected from one of hydrogen and C1-C5 hydrocarbon groups, X is selected from halogen, and q is selected from an integer of 1-3.

22. The polyolefin catalyst composition according to claim 20, characterized in that The molar ratio of aluminum in the alkyl aluminum compound to titanium in the catalyst is 20-500.

23. The polyolefin catalyst composition according to claim 20, characterized in that The molar ratio of aluminum in the alkyl aluminum compound to titanium in the catalyst is 30-300.

24. Use of the polyolefin catalyst according to any one of claims 1 to 9 or obtained by the preparation method according to any one of claims 10 to 18, or the polyolefin catalyst composition according to any one of claims 20 to 23 in olefin polymerization.

25. The use according to claim 24, characterized in that Application in ethylene homopolymerization or copolymerization of ethylene and other α-olefins.

26. The use according to claim 25, characterized in that The other α-olefin is at least one of propylene, 1-butene, 1-hexene, 1-octene, 1-pentene, and 4-methyl-1-pentene.

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