Ziegler-Natta catalyst component for ethylene slurry polymerization with narrow molecular weight distribution and preparation method thereof

Abstract

The present invention relates to a Ziegler-Natta catalyst component for ethylene slurry polymerization with a narrow molecular weight distribution and a preparation method thereof. The Ziegler-Natta catalyst component comprises a magnesium compound, a titanium compound, and an aluminate compound; the aluminate compound has the general structural formula (R 1 O)Al(OCOR 2 )2, where R 1 is selected from hydrocarbon groups or aromatic groups having 1 to 10 carbon atoms, R 2 The aluminate compound is selected from an alkyl group containing a linear, branched, or cyclic group of 2 to 20 carbon atoms. The aluminate compound plays a multifunctional role in the catalyst, making the resulting catalyst particles regular, spherical, and having a good particle size distribution. The catalyst component exhibits high catalytic activity, good hydrogen modulation sensitivity, and copolymerization performance when used in ethylene slurry polymerization or ethylene and α-olefin slurry copolymerization. The resulting high-density polyethylene resin has the advantages of high bulk density, narrow particle size distribution, low fine particle content, and narrow molecular weight distribution.

Description

Technical Field

[0001] The present invention belongs to the technical field of ethylene coordination polymerization catalysts, and specifically relates to a Ziegler-Natta catalyst for the polymerization and copolymerization of ethylene, in particular to an ethylene slurry polymerization Ziegler-Natta catalyst component, a preparation method and application of the catalyst component in ethylene slurry polymerization or copolymerization. Background Art

[0002] The molecular chain structure of polyethylene, such as molecular weight and molecular weight distribution, branching degree and distribution, and aggregate structure, is crucial for determining its performance. As polyethylene's applications expand, its variety is increasing. Adjusting catalysts, polymerization processes, and comonomers to meet the performance requirements of different applications is an effective approach to designing polyethylene's molecular structure. Molecular weight distribution (MWD) is a key specification for polyethylene resins, influencing both their performance and processing properties. To improve the performance of polyethylene and expand its application areas, new polyethylene products with varying molecular weight distributions are continuously being developed to meet the demands of various industries. Polyethylene resins with narrow molecular weight distributions exhibit reduced deformation and shrinkage in finished products, making them more suitable for film and injection molding. The narrower the molecular weight distribution, the better the physical properties and heat-sealing properties, as there are fewer extremely small and large molecules.

[0003] The development of new high-quality polyethylene products depends to a large extent on the continuous improvement and enhancement of catalyst performance. With the growing demand for high-quality polyethylene products in countries around the world, the requirements for polyethylene catalysts are also getting higher and higher. Simply pursuing high catalyst activity can no longer meet the requirements of polymerization processes and the market. Adjusting the microstructure of polyethylene resins through catalyst innovation is the development direction.

[0004] Metallocene catalysts are single-site coordination polymerization catalysts. Polyethylene resins produced using them typically have a molecular weight distribution of 2.0 to 3.0. Due to their significantly reduced oligomer content, odor generation during resin processing is reduced, and material properties are significantly improved. However, the high cost of supporting metallocene catalysts and the low activity of supported catalysts limit their application.

[0005] Compared to metallocene catalysts, polyethylene produced using Ziegler-Natta catalysts exhibits a wider molecular weight distribution, typically with a molecular weight distribution greater than 6.0. Furthermore, Ziegler-Natta catalysts offer advantages such as low cost and high catalytic activity. Therefore, the preparation of highly active supported Ziegler-Natta catalysts and the resulting polyethylene with a narrow molecular weight distribution and excellent material properties hold great promise for future applications. Research has revealed that electron donors play a crucial role in Ziegler-Natta catalysts. By introducing suitable electron donor compounds as catalyst components during the catalyst preparation process, the molecular weight distribution of polyethylene resins produced using existing Ziegler-Natta catalysts can be reduced to a molecular weight distribution less than 6. This represents an effective approach to improving Ziegler-Natta catalysts and is currently a hot topic in innovative research on Ziegler-Natta catalysts.

[0006] European Patent EP0373999 discloses the use of diisobutyl phthalate as an electron donor to prepare a Ziegler-Natta polyolefin catalyst, which reduces the molecular weight distribution to a certain extent, but the catalyst activity cannot meet the requirements of industrial production.

[0007] A Chinese patent application (Application No. 200780043013.5) discloses a catalyst component containing Ti, Mg, halogen, and an α,ω-diether compound for the polymerization of ethylene or a mixture of ethylene and other olefins to produce ethylene polymers with a narrow molecular weight distribution. However, the catalyst activity and polymer bulk density do not meet the requirements for industrial production.

[0008] A Chinese patent application (Application No. 201110306102.2) discloses a catalyst component comprising a Ti compound, MgCl2, silica gel, and a haloalkylene oxide for the polymerization or copolymerization of ethylene to produce a polyethylene resin with a narrow molecular weight. However, the low catalyst activity limits industrial production.

[0009] A Chinese patent application (application number 201610248520.3) provides a catalyst component for producing polyethylene with a narrow molecular weight distribution. The component comprises MgCl2, silica, a Ti-containing compound, an organophosphorus compound, and an aromatic ester compound, resulting in a narrow molecular weight distribution of the resulting polyethylene. However, this catalyst suffers from limitations such as low catalytic activity, low bulk density of the polymer product, a complex preparation process, and high raw material costs.

[0010] A Chinese patent application (application number 201310279626.6) provides a catalyst component for producing narrow molecular weight distribution polyethylene, comprising the reaction product of a magnesium halide / inorganic oxide support, an alcohol compound, a titanium compound, and a halogenated ether compound. However, this catalyst still suffers from low catalytic activity, low bulk density of the polymer product, and a broad molecular weight distribution (Mw / Mn = 4.78 to 6.85).

[0011] In addition, existing patents also use silicon compounds with the general formula R1xR2ySi(OR3)z, a class of siloxane compounds with organic functional groups (POSS), and organic boron compounds as electron donors. However, some of these electron donor compounds are very expensive, resulting in high catalyst production costs; some catalysts prepared with electron donors have irregular morphology, resulting in a large amount of fine powder generated during the polymerization process.

[0012] Therefore, it is necessary to improve the existing Ziegler-Natta catalyst to ensure that the catalyst has low production cost, high catalytic activity, good hydrogen sensitivity, and at the same time the produced polymer product has the characteristics of less fine powder, high bulk density, narrow particle size distribution, and narrow molecular weight distribution. Summary of the Invention

[0013] The present invention aims to overcome the shortcomings of the prior art and provide a Ziegler-Natta catalyst component having a large specific surface area, high porosity, and a narrow molecular weight distribution of a polymer product, and a preparation method thereof. The catalyst component has low production cost, high catalytic activity, and good hydrogen sensitivity. At the same time, the polymer product produced has the characteristics of less fine powder, high bulk density, narrow particle size distribution, and narrow molecular weight distribution.

[0014] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0015] A Ziegler-Natta catalyst component for ethylene slurry polymerization with a narrow molecular weight distribution, comprising a magnesium compound, a titanium compound, and an aluminate compound;

[0016] Wherein, the magnesium compound is a product obtained by dissolving a magnesium halide compound in a solvent system containing an organic alcohol or an organic ether compound;

[0017] The general formula of the titanium compound is TiR a X b , where R is C1~C 10 alkyl, alkoxy or aryl, aryloxy; X is halogen, a is 0, 1, 2 or 3, b is an integer from 1 to 4, a + b = 3 or 4;

[0018] The aluminate compound has the general structural formula (R 1 O)Al(OCOR2 )2, where R 1 is selected from hydrocarbon groups or aromatic groups having 1 to 10 carbon atoms, R 2 A group selected from a linear, branched or cyclic alkyl group containing 2 to 20 carbon atoms;

[0019] The ratio of each component is calculated based on each mole of magnesium halide in the magnesium compound: 0.1 to 10.0 moles of the organic alcohol or organic ether compound, 1.0 to 15.0 moles of the titanium compound, and 0.01 to 0.5 moles of the aluminate compound.

[0020] As a preferred embodiment of the present invention, the magnesium halide compound includes a dihalide magnesium compound, a halide alkyl magnesium compound, a halide alkoxy magnesium compound, and a halide aryloxy magnesium compound;

[0021] Among them, the magnesium dihalide compounds include magnesium chloride, magnesium iodide, magnesium fluoride, and magnesium bromide; the alkyl magnesium halide compounds include methyl magnesium halide, ethyl magnesium halide, propyl magnesium halide, butyl magnesium halide, isobutyl magnesium halide, hexyl magnesium halide, and pentyl magnesium halide; the alkoxy magnesium halide compounds include methoxy magnesium halide, ethoxy magnesium halide, isopropoxy magnesium halide, butoxy magnesium halide, and octyl magnesium halide; the aryloxy magnesium halide compounds include phenoxy magnesium halide and methylphenoxy magnesium halide; the magnesium halide compounds are used alone or as a mixture of two or more compounds.

[0022] As a preferred embodiment of the present invention, the titanium compound includes titanium halide or halogenated alkoxy titanium; wherein the titanium halide includes titanium tetrahalide, the alkoxy functional group in the halogenated alkoxy titanium has 1 to 20 carbon atoms, preferably the halogenated alkoxy titanium has 1 to 8 carbon atoms.

[0023] As preferred embodiments of the present invention, the aluminate compounds include isopropoxybis(diisooctylphosphate)aluminum, isopropoxybis(dodecyltoluenesulfonyloxy)aluminum, isopropoxybis(maleic acid monoisopropyl ester)aluminum, isopropoxybis(glycerol dilinolenic acid monohydroxy)aluminum, and isopropoxybis(p-isopropylphenyl acyloxy)aluminum.

[0024] As a preferred embodiment of the present invention, the organic alcohol compound includes linear or branched alkyl alcohols and halides, cycloalkanols and halides with carbon atoms of 1 to 20, and aromatic alcohols and halides or aromatic alkanols and halides with carbon atoms of 6 to 20; the organic ether compound is selected from one of C2 to C6 aliphatic ethers and C3 to C4 cyclic ethers;

[0025] Among them, the straight-chain or branched alkyl alcohol with a carbon number of 1 to 20 includes methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, decanol, dodecanol, tetradecanol, hexadecanol, and octadecanol; the aromatic alcohol or aromatic alkyl alcohol with a carbon number of 6 to 20 includes benzyl alcohol, phenylethyl alcohol, isopropyl benzyl alcohol, and cumyl alcohol; the organic alcohol compound and organic ether compound are selected from any one of the above compounds or a mixture of any two or more thereof.

[0026] The present invention also provides a method for preparing a Ziegler-Natta catalyst component for ethylene slurry polymerization having a narrow molecular weight distribution, comprising the following steps:

[0027] Step S1, dissolving a magnesium halide compound in an organic alcohol or an organic ether compound to prepare a homogeneous magnesium solution or microemulsion;

[0028] Step S2, reacting the homogeneous magnesium solution or microemulsion of step S1 with an aluminate compound to produce a solution or suspension of a magnesium-aluminum composition;

[0029] Step S3: reacting the magnesium-aluminum composition solution or suspension solution of step S2 with a titanium compound to produce a Ziegler-Natta catalyst component.

[0030] The average particle size and particle size distribution of the Ziegler-Natta catalyst component obtained in the present invention are related to the type of alcohol or ether used, the amount of alcohol or ether used, the type of magnesium compound, and the ratio of the magnesium compound to the alcohol or ether. During the preparation of the homogeneous magnesium solution or microemulsion, the reaction between the magnesium compound and the alcohol or ether can be carried out in the presence of a hydrocarbon solvent, with the reaction temperature controlled between 0 and 150°C and the reaction time controlled between 15 minutes and 5 hours. When the magnesium-aluminum composite solution or suspension reacts with the titanium compound, the shape and particle size of the precipitated solid titanium catalyst component depend primarily on the reaction conditions. To control the particle shape, the mixture of the magnesium compound solution, the aluminate compound, and the titanium compound is reacted at a sufficiently low temperature to produce the solid composite. The reaction temperature is controlled between -70 and 70°C, preferably between -50 and 50°C. After the contact reaction, the reaction temperature is slowly increased, and the reaction is continued at 50 to 150°C for 0.5 to 5 hours to ensure full reaction.

[0031] As a preferred embodiment of the present invention, step 1, the preparation of the magnesium compound is to dissolve the magnesium halide in a solvent system containing an organic alcohol or an organic ether compound, add an inert diluent, the dissolution temperature is 50 to 130 ° C, and the reaction time is controlled from 30 minutes to 4 hours to form a homogeneous solution or microemulsion of the magnesium compound;

[0032] Step 2: adding an aluminate compound to a magnesium compound homogeneous solution or microemulsion to dissolve the aluminate compound in the magnesium compound homogeneous solution or microemulsion to obtain a magnesium-aluminum composite solution or suspension;

[0033] Step 3: Cool the magnesium-aluminum composition solution or suspension to room temperature, and then drop it into the titanium compound maintained at 0 °C with stirring. After dropping, keep the mixture temperature at 0 °C for 1 hour, then raise the temperature to 60-130 °C within 2 hours with stirring, and keep this temperature for 2 hours. After the reaction ends, perform hot filtration separation on the generated solid, wash it with an inert diluent, and obtain a spherical solid titanium catalyst component after drying.

[0034] The present invention also provides a Ziegler-Natta catalyst for ethylene slurry polymerization, comprising:

[0035] Component ①: A Ziegler-Natta catalyst component for ethylene slurry polymerization with a narrow molecular weight distribution;

[0036] Component ②: An organoaluminum compound with the general formula AlR n X 3-n , where R is hydrogen or a hydrocarbon group with 1-20 carbon atoms, X is a halogen, 0 < n ≤ 3, and the alkylaluminum compound is used alone or two or more alkylaluminum compounds are used in combination; wherein, the molar ratio of aluminum in Component ② to titanium in Component ① is 1:10-1000, preferably 1:20-200.

[0037] The Ziegler-Natta catalyst for ethylene polymerization provided by the present invention can be used in ethylene polymerization or copolymerization reactions. In particular, the catalyst can be used for the homopolymerization of ethylene and can also be used for the copolymerization of ethylene with α-olefins having 3 or more carbon atoms such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, etc. To ensure a high polymerization reaction rate, the polymerization reaction needs to be carried out at a sufficiently high temperature. Generally, a suitable temperature is 20 to 200 °C, more preferably 60 to 95 °C; a suitable monomer pressure during the polymerization process is 0.1-10 MPa, more preferably 0.2-2.0 MPa.

[0038] The advantages and positive effects of the present invention are:

[0039] 1. In the present invention, an aluminate compound is added to the magnesium chloride-supported titanium-based Ziegler-Natta catalyst. The aluminate compound plays a multifunctional role in the catalyst, which can make the obtained catalyst particles regular in shape, spherical, with a good particle size distribution, having good hydrogen response ability and copolymerization performance; at the same time, it can also make the obtained polymerization product have a narrow molecular weight distribution.

[0040] 2. The spherical Ziegler-Natta catalyst particles provided by the present invention are formed by stacking a number of aluminate compound / Mg-Ti complex primary particles. The addition of the aluminate compound can make the formed Mg-Ti complex primary particles have a better morphology, so that the final Ziegler-Natta catalyst component has a more regular spherical shape, a concentrated particle size distribution, and less fine powder.

[0041] 3. Application results of the catalyst provided by the present invention in industrial equipment show that the Ziegler-Natta catalyst obtained by using an aluminate compound as the internal electron donor in the MgCl2 / TiCl4 catalyst has the advantages of high catalytic activity, good hydrogen sensitivity, good copolymerization performance, low oligomeric wax content, and low polymer fines. The molecular weight distribution of the resulting polyethylene resin is between 3.7 and 4.0, which is narrower than the molecular weight distribution of the catalyst system CN201310279626.6, which also has a narrow molecular weight distribution.

[0042] 4. The aluminate compound used in the present invention as an electron donor has the characteristics of wide industrial sources and low production costs. It can be applied to the preparation of Ziegler-Natta catalyst components for ethylene polymerization. It plays the role of supporting the skeleton in the final granular catalyst, forming catalyst particles with a microporous structure and having the function of regulating the molecular weight distribution of the polymerization product.

[0043] 5. The present invention uses an aluminate compound as a modifying component for the Ziegler-Natta catalyst. Aluminate compounds are a class of substances with two different functional groups: one is an inorganic-philic group that readily reacts chemically with inorganic surfaces; the other is an organic-philic group that can react chemically with other groups or form hydrogen bonds and dissolve therein. In addition, the aluminate compound itself has a certain associative structure, and the oxygen atom has a lone pair of electrons that can coordinate with magnesium chloride and titanium tetrachloride, which facilitates the uniform dispersion of Mg and Ti in the catalyst particles and prevents the formation of agglomerates. Therefore, in the resulting granular Ziegler-Natta catalyst component, the presence of the aluminate compound enables the magnesium chloride and titanium tetrachloride to be evenly dispersed in the catalyst particles, resulting in high porosity and large specific surface area. In addition to the above advantages, the inventors unexpectedly discovered that the polymer product obtained by catalyzing ethylene polymerization with the above-mentioned Ziegler-Natta catalyst component has the characteristic of a narrow molecular weight distribution. It is believed that the large steric hindrance of the aluminate compound participates in the coordination of Mg and Ti and the formation of active centers, affecting the structure and chemical environment of the Ziegler-Natta catalyst component, thereby increasing the structural similarity of each active center, thereby facilitating the acquisition of a polymer with a narrow molecular weight distribution. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0045] Example 1:

[0046] 4.76 g (50 mmol) of anhydrous magnesium chloride, 75 ml of decane, and 16.3 g (125 mmol) of isooctanol were heated to 130°C and reacted for 3 hours to obtain a homogeneous solution. To this solution was added 11 mmol of isopropoxybis(diisooctylphosphoyl)aluminum and stirred at 50°C for 2 hours to dissolve the isopropoxybis(diisooctylphosphoyl)aluminum. The resulting solution was cooled to room temperature and then added dropwise over 1 hour to 150 mL of titanium tetrachloride maintained at 0°C while stirring. After the addition was complete, the mixture was maintained at 0°C for 1 hour, then the temperature was raised to 120°C over 2 hours with stirring and maintained at this temperature for 2 hours. After the 2-hour reaction was complete, the resulting solid was separated by hot filtration. The solid catalyst was washed thoroughly with hexane and decane until no precipitated titanium compounds were detected in the washings. After drying, a solid titanium catalyst component was obtained. The analytical characterization results of the catalyst are shown in Table 1.

[0047] Ethylene polymerization

[0048] A 3.5 L stainless steel reactor was fully replaced with high-purity nitrogen, and then 2.0 L of hexane and 1 mL of 1.0 M triethylaluminum were added, along with 12 mg of the above-prepared catalyst. The reactor was heated to 75°C, and hydrogen was introduced to bring the pressure in the reactor to 0.28 MPa. Ethylene was then introduced to bring the total pressure in the reactor to 0.73 MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 2.

[0049] Example 2:

[0050] 4.76 g (50 mmol) of anhydrous magnesium chloride, 75 ml of decane, and 16.3 g (125 mmol) of isooctanol were heated to 130°C and reacted for 3 hours to obtain a homogeneous solution. To this solution, 20 mmol of isopropoxydi(dodecyltoluenesulfonyloxy)aluminum was added and stirred at 50°C for 2 hours to suspend the isopropoxydi(dodecyltoluenesulfonyloxy)aluminum in the solution. The resulting suspension was cooled to room temperature and then added dropwise over 1 hour to 150 mL of titanium tetrachloride maintained at 0°C while stirring. After the addition was complete, the mixture was maintained at 0°C for 1 hour, then the temperature was raised to 120°C over 2 hours with stirring and maintained at this temperature for 2 hours. After the 2-hour reaction was complete, the resulting solid was separated by hot filtration. The solid catalyst was thoroughly washed with hexane and decane until no precipitated titanium compounds were detected in the washings. After drying, a solid titanium catalyst component was obtained. The analytical characterization results of the catalyst are shown in Table 1.

[0051] Ethylene polymerization

[0052] A 3.5 L stainless steel reactor was fully replaced with high-purity nitrogen, and then 2.0 L of hexane and 1 mL of 1.0 M triethylaluminum were added, along with 12 mg of the above-prepared catalyst. The reactor was heated to 75°C, and hydrogen was introduced to bring the pressure in the reactor to 0.28 MPa. Ethylene was then introduced to bring the total pressure in the reactor to 0.73 MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 2.

[0053] Example 3:

[0054] The same as Example 1, except that the amount of isopropoxybis(diisooctylphosphoyloxy)aluminum added was 50 mmol. The analytical characterization results of the catalyst are shown in Table 1, and the polymerization results are shown in Table 2.

[0055] Example 4:

[0056] The same as Example 1, except that the amount of decane added was 50 mL. The analytical characterization results of the catalyst are shown in Table 1, and the polymerization results are shown in Table 2.

[0057] Example 5:

[0058] 4.76 g (50 mmol) of anhydrous magnesium chloride, 75 ml of decane, and 16.3 g (125 mmol) of isooctyl alcohol were heated to 130°C and reacted for 3 hours to obtain a homogeneous solution. The resulting homogeneous solution was cooled to room temperature and then added dropwise to 150 mL of titanium tetrachloride maintained at 0°C over 1 hour while stirring. 15 mmol of isopropoxybis(maleic acid monoisopropyl ester acyloxy)aluminum was added to the suspension. After the addition, the mixture was maintained at 0°C for 1 hour. The temperature was then raised to 120°C over 4 hours with stirring and maintained at this temperature for 2 hours. After the 2-hour reaction was complete, the resulting solid was separated by hot filtration. The solid catalyst was thoroughly washed with hexane and decane until no precipitated titanium compounds were detected in the washings. After drying, a solid titanium catalyst component was obtained. The analytical characterization results of the catalyst are shown in Table 1.

[0059] Ethylene polymerization

[0060] A 3.5 L stainless steel reactor was fully replaced with high-purity nitrogen, and then 2.0 L of hexane and 1 mL of 1.0 M triethylaluminum were added, along with 12 mg of the above-prepared catalyst. The reactor was heated to 75°C, and hydrogen was introduced to bring the pressure in the reactor to 0.28 MPa. Ethylene was then introduced to bring the total pressure in the reactor to 0.73 MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 2.

[0061] Example 6:

[0062] 4.76 g (50 mmol) of anhydrous magnesium chloride, 75 ml of decane, and 16.3 g (125 mmol) of isooctanol were heated to 130°C and reacted for 3 hours to obtain a homogeneous solution. 15 mmol of isopropoxybis(glyceryl dilinoleate monohydroxy)aluminum was added to this solution and stirred at 50°C for 2 hours to suspend the isopropoxybis(glyceryl dilinoleate monohydroxy)aluminum in the solution. The resulting suspension was cooled to room temperature and then added dropwise over 1 hour to 150 mL of titanium tetrachloride maintained at -20°C while stirring. Following the addition, the mixture was maintained at -20°C for 1 hour, then raised to 110°C over 6 hours with stirring and maintained at this temperature for 2 hours. After the 2-hour reaction, the resulting solid was separated by hot filtration. The solid catalyst was washed thoroughly with hexane and decane, respectively, until no precipitated titanium compound was detected in the washings. The solid catalyst was then dried to obtain a solid titanium catalyst component. The analytical characterization results of the catalyst are shown in Table 1.

[0063] Ethylene polymerization

[0064] A 3.5 L stainless steel reactor was fully replaced with high-purity nitrogen, and then 2.0 L of hexane and 1 mL of 1.0 M triethylaluminum were added, along with 12 mg of the above-prepared catalyst. The reactor was heated to 75°C, and hydrogen was introduced to bring the pressure in the reactor to 0.28 MPa. Ethylene was then introduced to bring the total pressure in the reactor to 0.73 MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 2.

[0065] Example 7:

[0066] 4.76 g (50 mmol) of anhydrous magnesium chloride, 75 ml of decane, and 16.3 g (125 mmol) of isooctanol were heated to 130°C and reacted for 3 hours to obtain a homogeneous solution. To this solution, 15 mmol of di(p-isopropylphenyl)aluminum isopropoxide was added and stirred at 50°C for 2 hours to suspend the di(p-isopropylphenyl)aluminum isopropoxide in the solution. The resulting suspension was cooled to room temperature and then added dropwise over 1 hour to 150 mL of titanium tetrachloride maintained at 10°C while stirring. Following the addition, the mixture was maintained at 10°C for 1 hour, then raised to 110°C over 3 hours with stirring and maintained at this temperature for 2 hours. After the 2-hour reaction, the resulting solid was separated by hot filtration. The solid catalyst was washed thoroughly with hexane and decane until no precipitated titanium compounds were detected in the washings. After drying, a solid titanium catalyst component was obtained. The analytical characterization results of the catalyst are shown in Table 1.

[0067] Ethylene polymerization

[0068] A 3.5 L stainless steel reactor was fully replaced with high-purity nitrogen, and then 2.0 L of hexane and 1 mL of 1.0 M triethylaluminum were added, along with 12 mg of the above-prepared catalyst. The reactor was heated to 75°C, and hydrogen was introduced to bring the pressure in the reactor to 0.28 MPa. Ethylene was then introduced to bring the total pressure in the reactor to 0.73 MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 2.

[0069] Example 8:

[0070] The same method as Example 1 was used, except that 0.5 mL of dehydrated 1-hexene was added during the polymerization. The analytical characterization results of the catalyst are shown in Table 1, and the polymerization results are shown in Table 2.

[0071] Example 9:

[0072] The same method as Example 1 was used, except that 2 mL of dehydrated 1-hexene was added during the polymerization. The catalyst analysis and characterization results are shown in Table 1, and the polymerization results are shown in Table 2.

[0073] Example 10:

[0074] The same as Example 1, except that hydrogen was added to 0.38 MPa during polymerization, and ethylene was introduced to bring the total pressure in the reactor to 0.73 MPa (gauge pressure). The analytical characterization results of the catalyst are shown in Table 1, and the polymerization results are shown in Table 2.

[0075] Comparative Example 1:

[0076] Same as Example 1 except that no aluminate compound was added. The analytical characterization results of the catalyst are shown in Table 1. Ethylene polymerization evaluation was the same as in Example 1. The polymerization activity, polymer bulk density, and particle size distribution results are shown in Table 2.

[0077] Comparative Example 2:

[0078] The catalyst was prepared according to the method of Catalyst C in Chinese Patent CN201310279626.6. The analytical characterization results of the catalyst are shown in Table 1. Ethylene polymerization was evaluated according to the method of Example 1. The polymerization activity, polymer bulk density, and particle size distribution are shown in Table 2.

[0079] Table 1 Catalyst physical property analysis results

[0080]

[0081] Table 2 Polymerization activity, polymer bulk density and particle size distribution results

[0082]

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, rather than to limit them. Although the embodiments of the present invention have been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the embodiments of the present invention.

Claims

1. A Ziegler-Natta catalyst component for ethylene slurry polymerization with a narrow molecular weight distribution, characterized in that: Including magnesium compounds, titanium compounds, aluminate compounds; Wherein, the magnesium compound is a product obtained by dissolving a magnesium halide compound in a solvent system containing an organic alcohol compound or an organic ether compound; The titanium compound has the general formula TiR a X b , where R is C1~C 10 alkyl, alkoxy; X is halogen, a is 0, 1, 2 or 3, b is an integer from 1 to 4, a+b=3 or 4; The ratios of the components are: 0.1 to 10.0 moles of the organic alcohol compound or organic ether compound, 1.0 to 15.0 moles of the titanium compound, and 0.01 to 0.5 moles of the aluminate compound per mole of magnesium halide in the magnesium compound; The aluminate compound is selected from one of isopropoxybis(diisooctylphosphate)aluminum, isopropoxybis(dodecyltoluenesulfonyloxy)aluminum, isopropoxybis(maleic acid monoisopropyl ester)aluminum, isopropoxybis(glycerol dilinolenic acid monohydroxy)aluminum, and isopropoxybis(p-isopropylphenyloxy)aluminum.

2. The ethylene slurry polymerization Ziegler-Natta catalyst component with narrow molecular weight distribution according to claim 1, characterized in that The magnesium halide compound includes a dihalide magnesium compound, a halide alkyl magnesium compound, a halide alkoxy magnesium compound, and a halide aryloxy magnesium compound; The magnesium dihalide compounds include magnesium chloride, magnesium iodide, magnesium fluoride, and magnesium bromide; the alkyl magnesium halide compounds include methyl magnesium halide, ethyl magnesium halide, propyl magnesium halide, butyl magnesium halide, isobutyl magnesium halide, hexyl magnesium halide, and pentyl magnesium halide; the alkoxy magnesium halide compounds include methoxy magnesium halide, ethoxy magnesium halide, isopropoxy magnesium halide, butoxy magnesium halide, and octyl magnesium halide; the aryloxy magnesium halide compounds include phenoxy magnesium halide and methylphenoxy magnesium halide; the magnesium halide compounds are used alone or as a mixture of two or more compounds.

3. The ethylene slurry polymerization Ziegler-Natta catalyst component with narrow molecular weight distribution according to claim 1, characterized in that The titanium compound includes titanium halide or halogenated alkoxy titanium; wherein the titanium halide includes titanium tetrahalide, and the alkoxy functional group in the halogenated alkoxy titanium has 1 to 20 carbon atoms.

4. The ethylene slurry polymerization Ziegler-Natta catalyst component with narrow molecular weight distribution according to claim 1, characterized in that The organic alcohol compound includes a linear or branched alkyl alcohol and its halides, a cycloalkanol and its halides, and an aromatic alcohol and its halides or aromatic alkyl alcohol and its halides with a carbon number of 6 to 20; the organic ether compound is selected from one of C2 to C6 aliphatic ethers and C3 to C4 cyclic ethers; The linear or branched alkyl alcohols having 1 to 20 carbon atoms include methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, decanol, dodecanol, tetradecanol, hexadecanol, and octadecanol; the aromatic alcohols or aromatic alkanols having 6 to 20 carbon atoms include benzyl alcohol, phenylethyl alcohol, isopropyl benzyl alcohol, and cumyl alcohol; and the organic alcohol compound and the organic ether compound are selected from any one or a mixture of any two or more of the above compounds.

5. The method for preparing the Ziegler-Natta catalyst component for ethylene slurry polymerization having a narrow molecular weight distribution according to claim 1, characterized in that: Here are the steps: Step S1, dissolving a magnesium halide compound in an organic alcohol or an organic ether compound to prepare a homogeneous magnesium solution or microemulsion; Step S2, reacting the homogeneous magnesium solution or microemulsion of step S1 with an aluminate compound to produce a solution or suspension of a magnesium-aluminum composition; Step S3: reacting the magnesium-aluminum composition solution or suspension solution of step S2 with a titanium compound to produce a Ziegler-Natta catalyst component.

6. The method for preparing a Ziegler-Natta catalyst component for ethylene slurry polymerization having a narrow molecular weight distribution according to claim 5, wherein: In the process of preparing a homogeneous magnesium solution or microemulsion, the reaction of the magnesium compound with an alcohol or ether is carried out in the presence of a hydrocarbon solvent, the reaction temperature is controlled at 0 to 150° C., and the reaction time is controlled at 15 minutes to 5 hours. When the magnesium-aluminum composition solution or suspension solution reacts with the titanium compound, the mixed solution of the magnesium-aluminum composition solution or suspension solution and the titanium compound is reacted at low temperature to produce a solid material composition, and the reaction temperature is controlled at -70 to 70° C. After the contact reaction, the reaction temperature is increased and the reaction is continued at 50 to 150° C. for 0.5 to 5 hours to fully react.

7. The method for preparing a Ziegler-Natta catalyst component for ethylene slurry polymerization having a narrow molecular weight distribution according to claim 5, wherein: Step 1, dissolving the magnesium halide in a solvent system containing an organic alcohol or an organic ether compound, adding an inert diluent, the dissolution temperature is 50-130°C, and the reaction time is controlled to be 30 minutes to 4 hours to form a homogeneous solution or microemulsion of the magnesium compound; Step 2: adding an aluminate compound to a magnesium compound homogeneous solution or microemulsion to dissolve the aluminate compound in the magnesium compound homogeneous solution or microemulsion to obtain a magnesium-aluminum composite solution or suspension; Step 3: Cool the magnesium-aluminum composition solution or suspension to room temperature, then add it dropwise to the titanium compound maintained at 0°C while stirring. After the addition is completed, the mixture temperature is maintained at 0°C for 1 hour, and then heated to 60-130°C within 2 hours while stirring, and this temperature is maintained for 2 hours. After the reaction is completed, the generated solid is separated by hot filtration, washed with an inert diluent, and dried to obtain a spherical solid titanium catalyst component.

8. A Ziegler-Natta catalyst for ethylene slurry polymerization, characterized in that include: Component ①: the Ziegler-Natta catalyst component for ethylene slurry polymerization having a narrow molecular weight distribution according to any one of claims 1 to 4; Component ②: an organoaluminum compound with the general formula AlR n X 3-n , where R is hydrogen or a hydrocarbon group with 1 to 20 carbon atoms, X is a halogen, 0 < n ≤ 3, and the organoaluminum compound is used alone or two or more organoaluminum compounds are used in combination; among them, the molar ratio of aluminum in Component ② to titanium in Component ① is 1:10 to 1000.

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