An ethoxymagnesium-kaolin composite carrier, a preparation method and application thereof

Abstract

The application discloses an ethoxymagnesium-kaolin composite carrier and a preparation method and application thereof, and belongs to the technical field of olefin polymerization reaction. The preparation method of the ethoxymagnesium-kaolin composite carrier comprises the following steps: adding kaolin in a reaction system of iodine-initiated magnesium powder and ethanol, and then sequentially performing washing and drying after the reaction is completed to obtain the ethoxymagnesium-kaolin composite carrier. Then, the composite carrier is used as raw material to prepare a solid Ziegler-Natta catalyst. That is, kaolin is added as raw material in the process of preparing the ethoxymagnesium composite carrier, the uniformity of the particle size and the bulk density of the prepared composite carrier are improved, then the composite carrier is used as raw material to prepare an ethoxymagnesium carrier type Ziegler-Natta catalyst, the catalyst has high activity and high hydrogen sensitivity, and the polypropylene product prepared under the action of the catalyst has good form, uniform particles and high bulk density.

Description

Technical Field

[0001] This invention belongs to the field of olefin polymerization technology, and particularly relates to an ethoxymagnesium-kaolin composite carrier, its preparation method and application. Background Technology

[0002] Polyolefins are widely used in various fields of production and daily life due to their excellent performance and relatively low cost. Since their inception, researchers have been pursuing improvements in polyolefin production efficiency and material properties to meet ever-expanding market demands, and catalyst design and improvement are crucial aspects of this process. Currently, the main types of polyolefin catalysts include Ziegler-Natta catalysts, metallocene catalysts, and non-metallocene catalysts. Among these, the Ziegler-Natta catalyst has the longest development history and the most widespread application. The types of supports used for this catalyst mainly include magnesium chloride supports prepared by the solvent extraction method, spherical supports for magnesium chloride alcohols, and alkoxy magnesium supports. Compared with magnesium chloride supports and spherical supports for magnesium chloride alcohols, alkoxy magnesium supports have the advantages of simple preparation processes and adjustable particle size. Catalysts prepared with alkoxy magnesium supports have attracted much attention due to their high activity, high hydrogen sensitivity, high stereoregularity, and good copolymerization performance.

[0003] However, propylene polymers obtained from alkoxymagnesium supported catalysts exhibit excellent properties such as superior particle morphology, low fine powder content, high activity, and high stereoregularity (EP1209172A1, EP1270604A1, EP1260524A1, EP1061088A1, US20140243190 A1, US00 8633124 B2, CN 201210575900.X, CN201310176782.X, CN201410704668.4, CN 202210291479.3). Therefore, the development of alkoxymagnesium supported catalysts has significant technological application value. To obtain such excellent catalyst components for olefin polymerization, it is first necessary to prepare high-performance dialkoxymagnesium supports.

[0004] Alkoxy magnesium, also known as magnesium alcohol, is sensitive to water. Published methods for preparing alkoxy magnesium include: (1) mechanically pulverizing the product obtained from the reaction of an alcohol and metallic magnesium to adjust the particle size; (2) controlling the appropriate molar ratio of magnesium alcohol to regulate the sphericity and particle size distribution of the alkoxy magnesium particles; (3) decarboxylating the magnesium carboxylate solution after spray drying to prepare spherical particles; (4) preparing particles with good morphology by reacting magnesium alcohol in the presence of an inert medium; and (5) removing the alcohol from the suspension of alkoxy magnesium and alcohol after spray drying to prepare spherical particles.

[0005] Currently, alkoxymagnesium is mostly prepared by reacting magnesium powder with alcohols (mostly ethanol (EtOH)) in the presence of an initiator. Taking the preparation of spherical alkoxymagnesium using iodine as an example, the process begins with iodine reacting with the oxide layer Mg(OH)₂ on the surface of the magnesium powder to activate it. The activated magnesium powder then reacts with EtOH to form amorphous ethoxymagnesium [Mg(OEt)₂]. Due to the low solubility of alkoxymagnesium compounds in alcohol solutions, the newly formed alkoxymagnesium immediately precipitates and deposits on the surface of the magnesium powder. Meanwhile, iodine reacts with magnesium powder to form MgI2; Mg(OEt)2, MgI2, and EtOH can form a quasi-stable complex nMg(OEt)2·MgI2·mEtOH that is soluble in EtOH; subsequently, tiny Mg(OEt)2 lamellae precipitate from the solution and deposit on the surface of the magnesium powder; as alkoxymagnesium crystals grow on the surface of the magnesium powder, some alkoxymagnesium crystals will peel off from the surface of the magnesium powder to form agglomerated seed crystals, and larger lamellae will precipitate from the solution and further crystallize onto the seed crystals to continue growing, eventually forming spherical Mg(OEt)2. For example, patents such as US20140243190 A1, US00 8633124 B2, CN201210575900.X, CN201310176782.X, CN201410704668.4, CN202210291479.3, CN111100218A, CN110498871A, and CN106749779A disclose methods for preparing alkoxymagnesium supports. These methods suffer from poor particle regularity.

[0006] Patent CN111875723A discloses an ethoxymagnesium support and its preparation method, as well as an ethoxymagnesium-supported Ziegler-Natta catalyst, its preparation method, and its application. The method includes: (1) contacting initiator dibromoethane, magnesium powder, and ethanol to carry out a first support reaction; (2) introducing magnesium powder and ethanol into the product obtained in step (1) to carry out a second support reaction, obtaining an ethoxymagnesium support; the first and second support reactions are carried out under pressure conditions, wherein the pressure is 0.1-1 MPa. The ethoxymagnesium support provided by this invention has a relatively regular particle morphology, but the catalytic activity of the prepared ethoxymagnesium-supported Ziegler-Natta catalyst needs to be improved.

[0007] Patent CN106749779A discloses an ethoxylated magnesium-modified support and its preparation as a Ziegler-Natta catalyst. The preparation method includes the following steps: ① Adding iodized magnesium powder to white mineral oil, then adding anhydrous ethanol at 10-20℃, reacting at 70-80℃ for 3-5 hours, washing and drying to obtain the ethoxylated magnesium support; ② Refluxing the ethoxylated magnesium support, glycol, ester, and solvent with solvent for 3-6 hours, filtering, and washing to obtain the ethoxylated magnesium-modified support. This preparation method introduces white mineral oil into the ethoxylated magnesium preparation process, increasing separation difficulty, raising production costs, reducing production efficiency, and making it unsuitable for large-scale production. Furthermore, the polymerization performance of this catalyst needs further improvement.

[0008] Patent CN 103214603 A discloses an ethoxymagnesium / montmorillonite / titanium tetrachloride polyethylene catalyst and its preparation method. The method involves adding ethoxymagnesium and a fatty alcohol to a decane solution to form a fatty alcohol suspension, then adding calcined montmorillonite and an electron donor, followed by the dropwise addition of titanium tetrachloride at low temperature. The catalyst is then obtained after washing and drying. This patent only discloses the catalyst preparation method and does not describe the catalyst's performance.

[0009] Patent CN1510059A discloses a method for synthesizing a montmorillonite supported catalyst, which can be used to prepare polyethylene / montmorillonite nanocomposites. However, this method requires the use of a large amount of methylaluminoxane to treat montmorillonite, which is complex, costly, and difficult to industrialize. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention proposes an ethoxymagnesium-kaolin composite support, its preparation method, and its applications. Specifically, under the action of an initiator, when alcohol reacts with magnesium powder, the addition of kaolin can prepare an alkoxymagnesium support with more regular particles, and the packing density and flowability of this support are significantly improved. The Ziegler-Natta catalyst prepared using this support exhibits excellent catalytic activity, enhanced hydrogen regulation performance, increased packing density of the prepared polymer, and improved barrier properties of the polymer.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A method for preparing an ethoxylated magnesium-kaolin composite carrier includes the following steps:

[0013] In an iodine-initiated reaction system of magnesium powder and ethanol, kaolin was added. After the reaction was complete, the mixture was washed and dried sequentially to prepare the ethoxymagnesium-kaolin composite carrier.

[0014] Optionally, the kaolin needs to be calcined before being added, and the calcination conditions are: calcination at 600℃ for 4 hours.

[0015] Optionally, the mass ratio of magnesium powder to kaolin is (4-24):1; preferably (6-12):1.

[0016] Optionally, the molar ratio of iodine to magnesium powder is (0.001-0.01):1, preferably 0.005:1.

[0017] Furthermore, the particle size of the magnesium powder is 50μm-350μm, preferably 75μm-150μm.

[0018] Optionally, the reaction conditions are: the reaction temperature is 50-80℃; preferably 70℃.

[0019] Optionally, the drying conditions are: drying under vacuum and at 80°C.

[0020] Optionally, the preparation method of the ethoxymagnesium-kaolin composite carrier includes the following steps:

[0021] (1) Add iodine and anhydrous ethanol to the reactor and stir until the iodine is completely dissolved;

[0022] (2) Add magnesium powder and anhydrous ethanol to the mixture obtained in step (1) in batches for reaction, and then add kaolin and anhydrous ethanol for reaction;

[0023] (3) After the reaction in step (2) is completed, sedimentation, filtration, washing and drying are carried out in sequence to prepare the ethoxymagnesium-kaolin composite carrier.

[0024] Furthermore, the number of times the ingredients are added in batches is 2-20 times, preferably 4-8 times; the time interval between each batch is 5-40 minutes, preferably 10 minutes.

[0025] Furthermore, the mass ratio of the total amount of magnesium powder to the total amount of anhydrous ethanol is 1:(9-18).

[0026] An ethoxylated magnesium-kaolin composite carrier was prepared by the above-described preparation method.

[0027] A Ziegler-Natta catalyst, the raw materials of which include the above-mentioned ethoxymagnesium-kaolin composite support.

[0028] The preparation method of the above Ziegler-Natta catalyst includes the following steps:

[0029] (1) Under an inert atmosphere, the magnesium ethoxylate-kaolin composite carrier was dispersed in toluene, cooled to -20~-10℃ and titanium tetrachloride was added dropwise, then the temperature was increased to 70℃, and then an internal electron donor was added to react for 1 hour, and then the temperature was increased to 110℃ to react for 2 hours.

[0030] (2) After the reaction in step (1) is completed, titanium component loading is carried out twice at this temperature; finally, the catalyst is washed with toluene and n-hexane in sequence and dried to obtain the Ziegler-Natta catalyst.

[0031] Optionally, the internal electron donor is selected from at least one of diisobutyl phthalate, di-n-butyl phthalate, diisooctyl phthalate, diethyl 2,3-diisopropylsuccinate, diethyl 2,3-diisobutylsuccinate, dimethyl 2,3-diisopropylsuccinate, dimethyl 2,3-diisobutylsuccinate, spirocyclic substituted butyl succinate, spirocyclic substituted isobutyl succinate, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, and 2,2-cyclopentyl-1,3-dimethoxypropane.

[0032] Optionally, in step (1), the ratio of the amount of toluene to ethoxymagnesium-kaolin composite carrier microspheres is 10 mL: 1 g;

[0033] Optionally, in step (2), the volume ratio of toluene to titanium tetrachloride added to the titanium component loading each time is 5:1.

[0034] The above-mentioned ethoxymagnesium-kaolin composite support is used in the field of catalytic polymerization of olefins to prepare polymers.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] The ethoxymagnesium-kaolin composite support particles prepared by this invention have better morphology, more uniform particle size, and higher bulk density (resulting in faster settling time and improved production efficiency in industrial production). Furthermore, the Ziegler-Natta catalyst prepared using the composite support exhibits high activity and good hydrogen sensitivity. Additionally, the polymer particles prepared using the above catalyst have more regular morphology, better flowability, and higher bulk density (generally, the bulk density of polypropylene prepared using ethoxymagnesium-supported Ziegler-Natta catalysts is ≤0.42 g / cm³). 3 The polypropylene prepared using the Ziegler-Natta catalyst of this invention has a bulk density as high as 0.50 g / cm³. 3 ). Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0038] Figure 1These are electron microscope images of the particle morphology of the ethoxymagnesium-kaolin composite carrier prepared in Example 1 of this invention;

[0039] Figure 2 This is an electron microscope image of the particle morphology of the Ziegler-Natta catalyst prepared in Example 1 of this invention;

[0040] Figure 3 These are electron microscope images of the particle morphology of the magnesium ethoxylate support prepared in Comparative Example 1 of this invention.

[0041] Figure 4 This is an electron microscope image of the particle morphology of the solid catalyst prepared in Comparative Example 1 of this invention. Detailed Implementation

[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0044] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0045] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0046] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0047] This invention provides an ethoxymagnesium-kaolin composite support and a method for preparing its Ziegler-Natta catalyst. The ethoxymagnesium support prepared by this method has better particle morphology, and the ethoxymagnesium-supported Ziegler-Natta catalyst prepared using it exhibits high activity and high hydrogen sensitivity. Furthermore, the resulting polyolefin product has good morphology, uniform particle size, and high bulk density.

[0048] In a first aspect, the present invention provides a method for preparing an ethoxylated magnesium-kaolin composite carrier, comprising the following steps:

[0049] (1) Add iodine and anhydrous ethanol to the reactor and stir until fully dissolved;

[0050] (2) Under stirring conditions, magnesium powder, anhydrous ethanol and calcined kaolin are added to the reaction vessel;

[0051] (3) After the reaction reaches the endpoint, the reaction system is filtered, washed with anhydrous ethanol and dried under vacuum to obtain ethoxymagnesium-kaolin composite carrier microspheres.

[0052] In some alternative embodiments, the mass ratio of magnesium powder to kaolin in step (2) is (4-24):1, preferably (6-12):1.

[0053] In some optional embodiments, the magnesium powder and anhydrous ethanol in step (2) can be added in batches, and the number of batches can be 2-20 times, preferably 4-8 times.

[0054] In some alternative embodiments, the time interval between batch additions is 5-40 minutes, preferably 10 minutes.

[0055] In some optional embodiments, the particle size of the magnesium powder is 50μm-350μm, preferably 75μm-150μm;

[0056] In some alternative embodiments, the mass ratio of the total amount of magnesium powder to the total amount of anhydrous ethanol is 1:(9-18), preferably 1:(10-16).

[0057] In some alternative embodiments, the molar ratio of iodine to magnesium powder is (0.001-0.01):1, preferably 0.005:1.

[0058] In some alternative embodiments, the reaction temperature is controlled at 50–80°C, preferably at 70°C.

[0059] In some alternative embodiments, the vacuum drying temperature is 80°C.

[0060] In some alternative embodiments, the reaction is carried out under the protection of an inert gas.

[0061] Secondly, this invention provides a method for preparing a Ziegler-Natta catalyst using the above-mentioned ethoxymagnesium-kaolin composite support microspheres, comprising the following steps:

[0062] (1) Add toluene and magnesium ethoxylate-kaolin composite carrier microspheres to the reactor, cool to -20~-10℃, and then add titanium tetrachloride solution dropwise to the reactor for 60~90min; after the dropwise addition is completed, start to heat up to 70℃ at a rate of 1℃ / 3min; heat up to 70℃, add internal electron donor compound to the reactor, and react at 70℃ for 1h; continue to heat up to 110℃ and react at this temperature for 2h, then settle and filter.

[0063] (2) Add toluene and titanium tetrachloride again, heat to 110°C, react for 2 hours, allow to settle, and filter.

[0064] (3) Add toluene and titanium tetrachloride again, heat to 110°C, react for 1 hour, settle and filter; finally add excess toluene and wash twice at 100°C, then wash 4-5 times with excess n-hexane solution at 60°C, and finally dry to obtain Ziegler-Natta catalyst.

[0065] In some alternative embodiments, the internal electron donor is at least one selected from diisobutyl phthalate, di-n-butyl phthalate, diisooctyl phthalate, diethyl 2,3-diisopropylsuccinate, diethyl 2,3-diisobutylsuccinate, dimethyl 2,3-diisopropylsuccinate, dimethyl 2,3-diisobutylsuccinate, spirocyclic substituted butyl succinate, spirocyclic substituted isobutyl succinate, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, and 2,2-cyclopentyl-1,3-dimethoxypropane.

[0066] In some alternative embodiments, in step (1), the ratio of toluene to ethoxymagnesium-kaolin composite carrier microspheres is 10 mL: 1 g.

[0067] In some alternative embodiments, in steps (2) and (3), the volume ratio of toluene to titanium tetrachloride is 5:1.

[0068] In some alternative embodiments, the molar ratio of the internal electron donor to magnesium in the ethoxymagnesium-kaolin composite carrier microspheres is 0.1 to 0.3.

[0069] In summary, this invention, through the introduction of kaolin composite modification, provides a simple, low-cost, and easily scalable method for preparing ethoxymagnesium support and its catalyst. It successfully solves a series of problems in the prior art, such as poor support morphology, insufficient catalyst activity and hydrogen regulation, and low polymer packing density, and produces high-performance catalysts and high-quality polyolefin products, which have significant industrial application value.

[0070] Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples of this invention can be obtained from conventional commercial sources or by existing technical methods. Unless otherwise specified, the experimental or testing methods are conventional methods in the art.

[0071] The catalyst composition in the examples or comparative examples was determined according to the following method:

[0072] (1) A certain amount of catalyst sample was extracted with heptane and sulfuric acid solution. After filtration, the aqueous layer was...

[0073] Used for the determination of Ti, wherein the Ti content is analyzed by absorbance method;

[0074] (2) The particle size and particle size distribution of the catalyst were determined using a MAS-TERSIZE2000 particle size analyzer manufactured by Malvern GmbH, UK. Hexane was used as the dispersant. The measurement range was 0.02~2,000.00 μm. The particle size distribution of the catalyst was determined using SPAN = (D... 90 -D 10 ) / D 50 express.

[0075] (3) The morphology of the carrier and catalyst was tested using a TM3030 Hitachi desktop scanning electron microscope manufactured by Beijing Youran Ruizhi System Technology Co., Ltd.

[0076] The performance parameters of each polymer in the examples or comparative examples were determined according to the following methods.

[0077] Determination of polymer melt index (MI): determined according to GB3682-2000;

[0078] Polymer bulk density determination: determined according to ASTM-D1895;

[0079] Isotacticity determination method: The heptane extraction method is used. Take 2g of dry polypropylene sample, place it in an extractor and extract with boiling heptane for 6 hours. After that, dry the residue to constant weight. The ratio of the obtained polymer weight (g) to 2g is the isotacticity.

[0080] The technical solution of the present invention will be further illustrated by the following embodiments.

[0081] Example 1

[0082] A method for preparing an ethoxylated magnesium-kaolin composite carrier includes the following steps:

[0083] (1) Under inert gas protection, start stirring and add 32 mL of anhydrous ethanol (the density of anhydrous ethanol is 0.79 g / cm³) to the reactor in sequence. 3 0.68g of iodine (initiator) is heated to 70℃ to dissolve the iodine.

[0084] (2) Then add 3.0g magnesium powder (75~150μm) and 32mL anhydrous ethanol to the mixture obtained in step (1), and react at 70℃ for 10min.

[0085] (3) Repeat step (2) 3 times (i.e., step (2) is performed 4 times in total), then add 1.0 g of kaolin that has been calcined (calcined at 600℃ for 4 h), and then add 48 mL of anhydrous ethanol. React at 70℃ for 3 h until the color turns white and no hydrogen is produced in the bubbler; wherein, the total mass ratio of magnesium to anhydrous ethanol is 13.7.

[0086] (4) Sedimentation and filtration were carried out, and then vacuum dried at 80°C for 3 hours to obtain ethoxymagnesium-kaolin composite carrier, wherein the magnesium content in the composite carrier was 19.3 (wt)%.

[0087] The particle size of the prepared ethoxymagnesium-kaolin composite carrier is 12-60 μm.

[0088] Figure 1 This is an electron micrograph of the particle morphology of the ethoxymagnesium-kaolin composite carrier prepared in Example 1 of the present invention.

[0089] The Ziegler-Natta catalyst was prepared using the above-mentioned ethoxymagnesium-kaolin composite support microspheres, and the specific steps are as follows:

[0090] Under inert gas protection, 10g of the above-mentioned ethoxymagnesium-kaolin composite carrier and 100mL of toluene were added to a five-necked reactor and stirred to form a suspension. Then, 20mL of titanium tetrachloride was added dropwise using a peristaltic pump while maintaining the temperature at -20℃. After the addition was completed in 1 hour, the system was slowly heated (at a rate of 1℃ / 3min) to 70℃, and 0.013mol / L of titanium tetrachloride was added. The catalyst was reacted with 2,2-diisopropyl-1,3-dimethoxypropane for 1 hour, then heated to 110°C and held at that temperature for 2 hours. The liquid was then filtered clean. The resulting solid was added to a mixed solution of 100 mL toluene and 20 mL titanium tetrachloride and reacted at 110°C for 2 hours. The liquid was filtered clean again. The resulting solid was then added to a mixed solution of 100 mL toluene and 20 mL titanium tetrachloride and reacted at 110°C for 1 hour. The liquid was then filtered clean. The resulting solid was washed twice with 120 mL toluene at 100°C, the liquid was filtered off, and then washed four times with 120 mL n-hexane at 60°C (using a total of 480 mL of hexane). The liquid was filtered off and the solid powder was dried to obtain the solid Ziegler-Natta catalyst. The titanium content in the overall catalyst was 2.65 wt%, and the SPAN was 1.09, as shown in Table 1. Electron micrographs of the catalyst particle morphology are shown below. Figure 2 As shown.

[0091] Polymerization characterization:

[0092] Evaluation of propylene bulk polymerization: A 2L stainless steel reactor was purged three times with high-purity nitrogen, 500g of liquid propylene was added, followed by 0.05MPa hydrogen. Then, a measured amount of 0.1mmol / L dicyclopentyldimethoxysilane, 1.5mmol / L triethylaluminum, and 0.005mmol / L (based on titanium atoms) of the previously prepared solid Ziegler-Natta catalyst were injected under high-purity nitrogen. The temperature was raised to 70℃ and the reaction was carried out for 1h. After polymerization, the pressure was released, and the product was expelled under nitrogen and dried to constant weight. The activity was calculated by weighing. The material ratio was molar ratio, with alkylaluminum co-catalyst: external electron donor: catalyst = 300:20:1. The polymerization results are shown in Table 2.

[0093] The preparation methods and polymerization characterization methods of the ethoxymagnesium-kaolin composite support and catalyst in Examples 2-18 are the same as those in Example 1, except that the only difference is the type and amount of raw materials added, as shown in Table 1.

[0094] Example 19

[0095] The composite support and catalyst preparation method and polymerization characterization method in Example 19 are the same as those in Example 1, except that step (2) is performed a total of 8 times in the entire preparation process of the support.

[0096] The final solid catalyst prepared in Example 19 had a mass percentage of Ti = 2.81% and SPAN = 1.18%.

[0097] The polymerization results of Examples 1-18 are shown in Table 2.

[0098] Table 1. Substances, dosages, and component contents in the catalyst added during the preparation of the composite support and catalyst.

[0099] Example alcohol to magnesium total mass ratio Kaolin addition amount Mass percentage of magnesium in the composite carrier (%) Types and amounts of electron donors added during catalyst preparation Titanium mass percentage (%) SPAN Example 2 13.7 2.0g 18.7 0.013 mol / L 2,2-Diisopropyl-1,3-Dimethoxypropane 3.02 0.99 Example 3 13.7 1.3g 19.0 0.013 mol / L 2,2-Diisopropyl-1,3-Dimethoxypropane 2.84 1.02 Example 4 13.7 2.0g 18.6 0.013 mol / L diethyl 2,3-diisopropylsuccinate 2.89 1.15 Example 5 10 2.0g 18.8 0.013 mol / L 2,2-Diisopropyl-1,3-Dimethoxypropane 2.48 0.89 Example 6 15 2.0g 18.5 0.013 mol / L 2,2-Diisopropyl-1,3-Dimethoxypropane 2.51 1.58 Example 7 10 2.0g 18.8 0.013 mol / L diisobutyl phthalate 2.72 0.92 Example 8 10 2.0g 18.8 0.013 mol / L spirocyclic substituted isobutyl succinate 2.85 0.90 Example 9 10 2.0g 18.8 0.013 mol / L 2,2-Diisobutyl-1,3-dimethoxypropane 2.42 0.88 Example 10 10 2.0g 18.8 0.013 mol / L 2,3-Diisobutylsuccinate diethyl ester 2.68 1.01 Example 11 10 2.0g 18.8 0.001 mol / L diethyl 2,3-diisopropylsuccinate; 0.007 mol / L 2,2-diisopropyl-1,3-dimethoxypropane 2.62 0.94 Example 12 10 2.0g 18.8 0.01 mol / L diethyl 2,3-diisobutylsuccinate; 0.003 mol / L 2,2-diisobutyl-1,3-dimethoxypropane 2.74 0.96 Example 13 10 2.0g 18.8 0.01 mol / L spirocyclic substituted butyl succinate and 0.003 mol / L 2,2-diphenyl-1,3-dimethoxypropane 2.99 0.98 Example 14 10 2.0g 18.8 0.016 mol / L 2,2-Diisobutyl-1,3-dimethoxypropane 2.13 0.85 Example 15 10 2.0g 18.8 0.01 mol / L 2,2-cyclopentyl-1,3-dimethoxypropane 3.15 1.03 Example 16 10 2.0g 18.8 0.0086 mol / L 2,2-Diisopropyl-1,3-Dimethoxypropane 2.78 1.06 Example 17 10 2.0g 18.8 0.026 mol / L 2,2-Diisopropyl-1,3-Dimethoxypropane 2.06 0.84 Example 18 10 2.0g 18.8 - 3.27 1.35

[0100] Note: In Examples 5-18, the mass ratio of total ethanol to total magnesium is based on the same amount of ethanol used in Example 1, with only the average single dose and total amount of magnesium adjusted.

[0101] Comparative Example 1

[0102] A method for preparing an ethoxymagnesium support includes the following steps:

[0103] (1) Under the protection of inert gas, start stirring and add 32 mL of anhydrous ethanol and 0.68 g of iodine (initiator) to the reactor in sequence, and heat to 70 °C to dissolve the iodine;

[0104] (2) Then add 3.0g magnesium powder (75~150μm) and 32mL anhydrous ethanol to the mixture in (1), and react at 70℃ for 20min.

[0105] (3) Repeat step (2) 3 times, react at 70°C for 3 hours, until the color turns white and no hydrogen is produced in the bubbler;

[0106] (4) Sedimentation, filtration, and then vacuum drying at 80°C for 3 hours to prepare ethoxy magnesium carrier.

[0107] The particle size of the carrier prepared in Comparative Example 1 was 4-86 μm.

[0108] Figure 3 The image shows an electron microscope image of the support prepared in Comparative Example 1.

[0109] The Ziegler-Natta catalyst was prepared using the above-mentioned ethoxymagnesium supported microspheres, and the specific steps are as follows:

[0110] Under inert gas protection, 10 g of magnesium ethoxylate support and 100 mL of toluene were added to a five-necked reactor and stirred to form a suspension. Then, 20 mL of titanium tetrachloride was added dropwise using a peristaltic pump while maintaining the temperature at -20 °C. After the addition was completed in 1 hour, the system was slowly heated (at a rate of 1 °C / 3 min) to 70 °C, and 0.013 mol / L of titanium tetrachloride was added. The mixture was reacted with 2,2-diisopropyl-1,3-dimethoxypropane for 1 hour, then heated to 110°C and held at that temperature for 2 hours. The liquid was then filtered clean. The resulting solid was added to a mixed solution of 100 mL toluene and 20 mL titanium tetrachloride and reacted at 110°C for 2 hours. The liquid was then filtered clean. The resulting solid was added to a mixed solution of 100 mL toluene and 20 mL titanium tetrachloride and reacted at 110°C for 1 hour. The liquid was then filtered clean. The resulting solid was washed twice with 120 mL toluene at 100°C, the liquid was filtered off, and then washed four times with 120 mL n-hexane at 60°C (480 mL n-hexane was used in total). The liquid was filtered off and the solid powder was dried to obtain the solid catalyst. The titanium content was 2.80 (wt)% and the SPAN was 1.89.

[0111] Figure 4 The image shows the particle morphology of the solid catalyst prepared in Comparative Example 1.

[0112] The propylene polymerization was the same as in Example 1, and the polymerization results are shown in Table 2.

[0113] Comparative Example 2

[0114] The preparation methods of the support and catalyst in Comparative Example 2 and the polymerization characterization methods are the same as those in Comparative Example 1. The only difference is that 2,2-diisopropyl-1,3-dimethoxypropane was not added during the catalyst preparation process.

[0115] In Comparative Example 2, the final solid catalyst prepared contained Ti = 3.25% and SPAN = 1.95% by mass.

[0116] The propylene polymerization was the same as in Example 1, and the polymerization results are shown in Table 2.

[0117] Table 2. Results of propylene bulk polymerization with different catalysts

[0118] catalyst Activity (gPE / gCat.) <![CDATA[Bulk density (g / cm 3 )]]> <![CDATA[MI 2.16Kg (g / 10min)]]> Isotacticity (%) Example 1 38000 0.50 1.85 98.2 Example 2 32800 0.48 1.28 97.8 Example 3 36200 0.43 1.12 98.0 Example 4 30650 0.48 0.85 97.2 Example 5 42450 0.50 1.80 98.3 Example 6 41000 0.50 1.76 98.2 Example 7 28000 0.47 0.72 97.5 Example 8 29700 0.48 0.50 97.2 Example 9 38700 0.49 1.34 98.2 Example 10 35800 0.48 1.26 98.2 Example 11 46800 0.50 2.20 97.8 Example 12 44290 0.50 2.36 98.0 Example 13 42480 0.49 2.21 98.2 Example 14 25000 0.47 1.60 99.2 Example 15 23000 0.45 1.67 96.4 Example 16 33800 0.47 2.27 96.7 Example 17 35000 0.50 1.60 98.8 Example 18 25800 0.45 0.89 94.6 Example 19 39000 0.50 1.50 98.3 Comparative Example 1 22000 0.42 0.43 97.2 Comparative Example 2 16000 0.38 0.68 92.0

[0119] As can be seen from Table 2, the ethoxymagnesium-kaolin composite support Ziegler-Natta catalyst prepared in this invention exhibits significantly better overall performance than the comparative example.

[0120] First, regarding catalytic activity, the catalysts of Examples 1-19 of this invention exhibited activities ranging from 23,000 to 46,800 gPP / gCat., significantly higher than Comparative Example 1 (22,000 gPP / gCat.) and Comparative Example 2 (16,000 gPP / gCat.). Among these, Example 11 showed the highest activity, reaching 46,800 gPP / gCat., indicating that introducing a kaolin composite support and optimizing the internal electron donor formulation can significantly improve catalyst efficiency.

[0121] Secondly, this invention demonstrates a significant advantage in bulk density, a key indicator of polymer particle morphology and processing performance. The polypropylene bulk densities obtained in Examples 1-19 are generally between 0.43 and 0.50 g / cm³, with Examples 1, 5, 6, 11, 12, and 19 all reaching a peak of 0.50 g / cm³. This is significantly better than Comparative Example 1 (0.42 g / cm³) and Comparative Example 2 (0.38 g / cm³). High bulk density means denser polymer particles, which can significantly improve the capacity and efficiency of downstream granulation and processing.

[0122] Regarding hydrogen regulation sensitivity, measured by melt index (MI), the MI values ​​of most catalysts in the embodiments of the present invention are in the range of 1.0-2.4 g / 10min, which are significantly higher than those of Comparative Example 1 (0.43 g / 10min) and Comparative Example 2 (0.68 g / 10min), indicating that they are more sensitive to hydrogen regulation and are more likely to produce high-flow polypropylene products.

[0123] Finally, regarding the stereoregularity (isotacticity) of the polymer, the isotacticity of the embodiments of the present invention is generally between 97.2% and 99.2%, which is much higher than that of Comparative Example 2 (92.0%), indicating that the catalyst can effectively control the stereostructure of the polymer and ensure the excellent performance of the product.

[0124] In summary, compared with Comparative Example 1 and Comparative Example 2, the catalyst of the present invention has significantly improved in terms of activity, polymer packing density and hydrogen sensitivity, while maintaining excellent stereoregularity, and has superior overall performance.

[0125] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an ethoxylated magnesium-kaolin composite carrier, characterized in that, Includes the following steps: (1) Add iodine and anhydrous ethanol to the reactor and stir until the iodine is completely dissolved; (2) Add magnesium powder and anhydrous ethanol to the mixture obtained in step (1) in batches for reaction, and then add kaolin and anhydrous ethanol for reaction; (3) After the reaction in step (2) is completed, sedimentation, filtration, washing and drying are carried out in sequence to prepare the ethoxymagnesium-kaolin composite carrier; The mass ratio of magnesium powder to kaolin is (4-24):1; The molar ratio of iodine to magnesium powder is (0.001-0.01):1; The conditions during the reaction process are: the reaction temperature is 50–80°C; The number of times the ingredients are added in batches is 2-20 times; the time interval between each batch is 5-40 minutes. The mass ratio of the total amount of magnesium powder to the total amount of anhydrous ethanol is 1:(9-18).

2. An ethoxylated magnesium-kaolin composite carrier, characterized in that, It is prepared by the preparation method described in claim 1.

3. A Ziegler-Natta catalyst, characterized in that, The raw materials include the ethoxymagnesium-kaolin composite carrier as described in claim 2.

4. A method for preparing the Ziegler-Natta catalyst as described in claim 3, characterized in that, Includes the following steps: (1) Under an inert atmosphere, the ethoxymagnesium-kaolin composite carrier described in claim 2 is dispersed in toluene, cooled to -20~-10℃ and titanium tetrachloride is added dropwise, then the temperature is programmed to rise to 70℃, then an internal electron donor is added and reacted for 1 hour, and then the temperature is raised to 110℃ and reacted for 2 hours; wherein, the ratio of toluene to ethoxymagnesium-kaolin composite carrier is 10mL:1g; (2) After the reaction in step (1) is completed, titanium component loading is carried out twice at this temperature. The volume ratio of toluene to titanium tetrachloride added in each titanium component loading is 5:

1. Finally, the catalyst is washed with toluene and n-hexane in sequence and dried to obtain the Ziegler-Natta catalyst.

5. The method for preparing a Ziegler-Natta catalyst according to claim 4, characterized in that, The internal electron donor is selected from at least one of diisobutyl phthalate, di-n-butyl phthalate, diisooctyl phthalate, diethyl 2,3-diisopropylsuccinate, diethyl 2,3-diisobutylsuccinate, dimethyl 2,3-diisopropylsuccinate, dimethyl 2,3-diisobutylsuccinate, spirocyclic substituted butyl succinate, spirocyclic substituted isobutyl succinate, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, and 2,2-cyclopentyl-1,3-dimethoxypropane.

6. The application of the ethoxymagnesium-kaolin composite support as described in claim 2 in the field of catalytic olefin polymerization to prepare polymers.

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