CN110240668A - Internal Electron Donor, Catalyst Component, Preparation Method and Application of Ziegler-Natta Catalyst - Google Patents

Abstract

The present invention relates to a kind of internal electron donors, catalytic component, preparation method and applications for vinyl polymerization Ziegler-Natta catalyst.Wherein for the internal electron donor structure such as shown in (I), catalytic component includes a kind of magnesium complex, a kind of titanium compound, a kind of internal electron donor as described in leading to formula (I).The catalyst is used to show higher catalytic activity, preferable hydrogen response and preferable copolymerization performance when vinyl polymerization or combined polymerization, is particularly suitable for ethylene slurry polymerization and ethene gas-phase polymerization to produce high-bulk-density, narrow size distribution, the polymer that fine particle content is few, wax content is low and molecular weight distribution is wide.

Description

Internal electron donor, catalyst component and preparation method of Ziegler-Natta catalyst and its application

technical field

The invention belongs to the field of ethylene polymerization catalysts, and relates to a Ziegler-Natta catalyst, in particular to an electron donor and a catalyst component of the Ziegler-Natta catalyst used for ethylene polymerization and its application in ethylene polymerization.

technical background

In recent years, the development and application of high-end polyolefin special materials has always been the focus in this field, and the research and development of corresponding catalysts is also a difficult point in the field of polyolefin resin research. The composition and structure of catalysts have great influence on the structure and performance of polyolefin resins. important influence. Titanium-based Ziegler-Natta catalysts are still the main catalysts for the industrial production of polyolefin resins. They have been developed with high catalytic activity, good hydrogen adjustment sensitivity, good copolymerization performance, uniform particle size distribution, less fine powder, and low wax content. The production of stable and controllable polyolefin catalysts is the goal pursued by researchers and engineers. There are many documents and patents reporting many methods for preparing magnesium chloride-supported titanium-based Ziegler-Natta catalysts as catalysts for olefin polymerization and copolymerization. Depending on the polymerization process, the performance of the corresponding catalyst is also different, so the production method of the corresponding catalyst is also slightly different. For example, the Ziegler-Natta catalyst used in the ethylene gas-phase fluidized-bed polymerization process requires good catalyst particle shape and less fine powder, so that the polyethylene fine powder produced when used in ethylene gas-phase fluidized-bed polymerization can avoid static electricity. Reactor slices. Catalysts for gas-phase polymerization of ethylene are generally loaded with active components directly on inert carriers with large surfaces such as silica gel. Since the particle diameter of silica gel is easy to control and the particle shape is good, catalyst particles with uniform particles can be obtained. However, since the loading amount of the active components on the carrier is limited, the titanium content in the catalyst prepared by this method is low, and the polymerization activity is not high. For example, in the patent CN99103280, MgCl ₂ and SiO ₂ are used as the carrier, and TiCl ₄ is the active component. The preparation method of the catalyst is as follows: MgCl ₂ is reacted with TiCl ₄ in THF to form a catalyst mother liquor, and then activated with alkylaluminum The treated carrier SiO ₂ was mixed, and the catalyst precursor component was prepared after removing part of THF. When used in ethylene polymerization, due to the low content of titanium in the catalyst, the polymerization activity is low. Therefore, although this catalyst system can be used in the gas-phase fluidized bed polymerization process of ethylene, it is difficult to be suitable for the slurry polymerization process of ethylene due to its low catalytic activity.

The Ziegler-Natta catalyst used in the ethylene slurry polymerization process requires high catalyst activity and good hydrogen adjustment sensitivity. At the same time, it is required to have less fine powder and less wax content in the polymerization product, so as to ensure continuous long-term operation of the production unit. The preparation method for this catalyst is to dissolve magnesium compounds such as magnesium chloride in a solvent to obtain a uniform solution, and then mix the solution with a titanium compound and an electron donor, and obtain a solid containing magnesium, titanium and an electron donor by precipitation. matter, and the solid matter is treated with an excess of liquid titanium compound to obtain catalyst particles.如中国专利CN1099041A、CN1229092、CN1958620A、CN100513433、CN100532406、CN102344514B、CN102344515B、CN101274967B、CN102453172A、CN102432726A、CN102344506A、CN102344507、CN102286119A、CN102286120A等公开了制备这种催化剂的方法。 The preparation of this catalyst is generally to control the particle size and particle shape of the catalyst through the crystallization and precipitation process of magnesium chloride, and add electron donor compounds during the precipitation process to improve the performance of the catalyst. The added electron donor compound not only affects the particle shape of the catalyst, but also affects the hydrogen modulation sensitivity and copolymerization performance of the catalyst, so the selection of the electron donor is a key to the development of this type of catalyst. For example, Chinese patent CN1958620A adopts tetraethoxysilane as electron donor, and CN2010102089331 adopts a class of siloxane compound (POSS) with organic functional groups as electron donor, but the price of this siloxane compound is very expensive, which limits its application in catalysts.

Contents of the invention

The present invention is aimed at the deficiency of above-mentioned prior art method, provides a kind of electron donor of ethylene polymerization Ziegler-Natta catalyst, the catalyst component that comprises this electron donor, the catalyst that comprises this catalyst component, and its in ethylene polymerization, Applications in copolymerization reactions.

The electron donor of a kind of Ziegler-Natta catalyst, for replacing ethyl acetate compound, has following structure:

In the formula: R ₁ , R ₂ and R ₃ can be the same or different, and they are respectively selected from hydrogen, methyl, ethyl, C3-C10 alkyl, cycloalkyl, aryl, halogen, alkylphosphono, alkoxy group and haloalkoxy group, etc.;

Preferably, the substituted ethyl acetate compound is: ethyl chloroacetate, ethyl bromoacetate, ethyl iodoacetate, ethyl dichloroacetate, ethyl dibromoacetate, ethyl diiodoacetate, ethyl trichloroacetate, trichloroacetate Ethyl bromoacetate, ethyl triiodoacetate, ethyl trimethylacetate, ethyl cyanoacetate, ethyl dimethylphosphonoacetate, ethyl diacetoacetate, ethyl p-tolueneacetate, 2-(chloromethyl Oxy)ethyl acetate, etc.

A catalyst component comprising the internal electron donor, the catalyst component comprising:

①Magnesium complexes; ②Titanium compounds; ③Substituted ethyl acetate compounds;

The magnesium complex described in component ① is a product obtained by dissolving magnesium halide in a solvent system containing an organic alcohol compound; the organic alcohol compound is a straight chain or branched chain with 1 to 10 carbon atoms. Alkyl alcohols, cycloalkanols with 3 to 10 carbon atoms, aromatic alcohols with 7 to 20 carbon atoms, and halogenated organic alcohols; the above alcohols are a single type or a mixture of two or more alcohols.

The general formula of the titanium compound described in component ② is Ti(OR) _a X _b , where R is a C1-C10 aliphatic hydrocarbon group or aryl group, X is a halogen, a is 0, 1, 2 or 3, and b is Integer of 1 to 4, a+b=3 or 4.

Calculated per mole of magnesium halide, the content of the organic alcohol compound is 0.1-10.0 moles, the content of the substituted ethyl acetate compound is 0.05-1.0 moles, and the content of the titanium compound is 1.0-15.0 moles.

There are two ways to replace the addition of ethyl acetate compound, which are:

A kind of preparation method of described catalyst component, the steps are as follows:

(1) Dissolving magnesium halide in a solvent system containing an organic alcohol compound, adding an inert diluent, the dissolution temperature is 50-125°C to obtain component ①, adding component ③ to component ① to obtain a reaction solution;

⑵At -24°C~10°C, contact the reaction solution with component ②, and slowly raise the temperature of the mixture to 80~125°C, the solid matter gradually precipitates and forms particles, after a certain period of reaction, remove the unreacted matter and solvent , and washed with an inert diluent to obtain a particle-shaped solid titanium catalyst component.

A kind of preparation method of described catalyst component, the steps are as follows:

(1) Dissolve magnesium halide in a solvent system containing organic alcohol compounds, add an inert diluent, and dissolve at a temperature of 50-125°C to obtain component ①;

(2) At -24°C to 10°C, first contact component ① and component ② for a contact reaction, then add component ③, and slowly raise the temperature of the mixture to 80-125°C, the solids will gradually precipitate and form particles, and react for a certain period of time Afterwards, unreacted substances and solvents are removed, and an inert diluent is used for washing to obtain a particle-shaped solid titanium catalyst component.

A catalyst comprising said catalyst component, comprising:

(1) the catalyst component described in claim 3;

(2) Organoaluminum compounds with the general formula AlR _n X _3-n , where R is a hydrogen atom or a hydrocarbon group with 1 to 20 carbon atoms, X is a halogen, and 0<n≤3.

The molar ratio of aluminum in component (2) to titanium in component (1) is 10-1000.

An application of the electron donor in ethylene polymerization.

An application of the catalyst component or catalyst in ethylene polymerization.

The catalyst of the present invention is prepared by the following steps: (1) dissolving a magnesium halide compound in an organic alcohol compound to prepare a homogeneous magnesium solution; (2) reacting the homogeneous magnesium solution with at least one substituted ethyl acetate compound to produce magnesium Composition solution; (3) reacting the magnesium composition solution with a titanium compound to produce a solid titanium catalyst, and the reaction with the titanium compound can be performed once or multiple times. The magnesium compound may be a magnesium halide compound. The types of magnesium halide compounds used in the present invention may include the following types: magnesium dihalide compounds such as magnesium chloride, magnesium iodide, magnesium fluoride, and magnesium bromide; alkylmagnesium halide compounds such as methylmagnesium halide, ethylmagnesium halide , propylmagnesium halide, butylmagnesium halide, isobutylmagnesium halide, hexylmagnesium halide, and pentylmagnesium halide; alkoxymagnesium halide compounds such as methoxymagnesium halide, ethoxymagnesium halide, isopropoxyhalide Magnesium halides, butoxymagnesium halides and octoxymagnesium halides; aryloxymagnesium halides such as phenoxymagnesium halides and methylphenoxymagnesium halides. These magnesium compounds may be used as a single compound or as a mixture of two or more compounds. In addition, the above-mentioned magnesium compounds can be effectively used in the form of complex compounds with other metals. Other magnesium compounds include compounds that may exist depending on the method of preparation of the magnesium compound but cannot be represented by a molecular formula, and may generally be regarded as a mixture of magnesium compounds. For example, the following compounds can be used as the magnesium compound: a compound obtained by reacting a magnesium compound with a substituted ethyl acetate compound, a halogen-containing silane compound, an ester, or an alcohol; Compounds obtained by reacting in the presence of phosphorous or thionyl chloride. The magnesium compound can be a magnesium halide, especially magnesium chloride or an alkylmagnesium chloride with an alkyl group of 1 to 10 carbon atoms; an alkoxymagnesium chloride with an alkoxy group of 1 to 10 carbon atoms; An aryloxymagnesium chloride of an aryloxy group with 6 to 20 carbon atoms. The magnesium solution used can be prepared by dissolving the magnesium compound in alcohol to make a solution in the presence or absence of a hydrocarbon solvent. The types of hydrocarbon solvents used in the present invention can be aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane and kerosene; alicyclic hydrocarbons such as cyclobenzene, methylcyclobenzene, cyclohexane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, etc.; halogenated hydrocarbons such as dichloropropane, dichloroethylene, trichloroethylene, carbon tetrachloride, and chlorobenzene. The preparation of the magnesium solution from the magnesium compound can be carried out with or without the addition of a hydrocarbon solvent using an alcohol as a solvent. The type of alcohol may include alcohols containing 1 to 20 carbon atoms such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, decanol, dodecanol, tetradecanol, hexadecanol Alcohol, stearyl alcohol, benzyl alcohol, phenethyl alcohol, cumyl alcohol, and cumyl alcohol, preferably alcohols can be selected from alcohols containing 1 to 12 carbon atoms. The average particle size and particle size distribution of the resulting catalyst can depend on the type of alcohol used, the amount of alcohol used, the type of magnesium compound and the ratio of magnesium compound to alcohol. During the preparation of the magnesium solution, the reaction of the magnesium compound with the alcohol may be carried out in the presence of a hydrocarbon solvent. The reaction temperature may be at least about -25°C, preferably about -20 to 150°C, or more preferably about -10 to 110°C, although it may vary depending on the type and amount of alcohol used. The reaction time may be about 15 minutes to 10 hours, or preferably about 30 minutes to 4 hours.

When the magnesium composition solution reacts with the titanium compound, the shape and size of the precipitated solid titanium catalyst component mainly depends on the reaction conditions. In order to control particle shape, it may be preferable to react the magnesium compound solution with a mixture of titanium compound, substituted ethyl acetate compound at a temperature low enough to produce a solid matter composition. The substituted ethyl acetate compound can be added to the system before the magnesium compound solution is in contact with the titanium compound, or can be added to the system after the magnesium compound solution is in contact with the titanium compound. The reaction temperature may be about -70 to 70°C, more preferably about -50 to 50°C. After the contacting reaction, the reaction temperature is slowly increased for a sufficient reaction at about 50 to 150° C. for about 0.5 to 5 hours. The solid catalyst particles obtained as described above can then be reacted with additional titanium compounds. The titanium compound used may be a titanium halide or an alkoxy titanium halide, wherein the alkoxy functional group has 1 to 20 carbon atoms. Mixtures of these compounds may also be used where appropriate. Of these compounds, titanium halides or alkoxytitanium halides in which the alkoxy functional group has 1 to 8 carbon atoms are suitable, and more preferred compounds are titanium tetrahalides. The catalyst prepared by the method of the present invention can be used for the polymerization and copolymerization of ethylene. In particular, the catalyst can be used for the homopolymerization of ethylene, and also for ethylene with α-olefins having 3 or more carbon atoms such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene Copolymerization of alkenes or 1-hexene. Polymerization using the catalysts of the present invention can be carried out with a catalyst system comprising: (1) a solid titanium complex catalyst as described herein comprising magnesium, titanium and an electron-donating compound; (2) an alkyl metal compound or Aluminometallic compounds. The organometallic compound is a trialkylaluminum having an alkyl group of 1 to 6 carbon atoms, such as triethylaluminum and triisobutylaluminum, or a mixture thereof. Where appropriate, organoaluminum compounds with one or more halogen or hydrogen radical groups can also be used, such as ethylaluminum dichloride, diethylaluminum chloride, ethylaluminum sesquichloride, or diisobutylaluminum hydride . The solid titanium complex catalyst components described herein may be prepolymerized with ethylene or alpha-olefins prior to use in polymerization reactions. The prepolymerization can be carried out in the presence of a hydrocarbon solvent such as hexane, at a sufficiently low temperature, under the pressure of ethylene or α-olefin, and in the presence of the above-mentioned catalyst component and an organoaluminum compound such as triethylaluminum . The molar ratio of the organoaluminum compound to the titanium in the solid titanium complex catalyst in the polymerization reaction system is 1-1000, preferably 20-200. In order 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 about 20 to 200°C, more preferably about 60 to 95°C. A suitable monomer pressure during polymerization is 0.1-10.0 MPa, more preferably about 0.2-5.0 MPa.

Advantages and positive effects of the present invention

1. The present invention finds that the use of substituted ethyl acetate compounds as electron donors added to titanium-based Ziegler-Natta catalysts supported by magnesium chloride can make the obtained catalyst particles regular in shape, particle-shaped, with good particle size distribution and fine-grained polymerization products. Less powder, high bulk density, and the obtained catalyst has good hydrogen adjustment sensitivity and copolymerization performance.

2. The molecular structure of the substituted ethyl acetate compound used in the present invention contains groups or atoms with higher electronegativity such as halogen, phosphine, and cyano groups. These electron-rich groups participate in the coordination between magnesium and titanium, affecting The chemical environment of the titanium active center can thus achieve the purpose of regulating the hydrogen modulation sensitivity and copolymerization performance of the catalyst.

3. The substituted ethyl acetate compound used in the present invention belongs to commonly used chemicals with low production cost and can be applied to the industrial preparation of catalysts.

Detailed ways

The present invention will be further described in detail below through the specific examples, the following examples are only descriptive, not restrictive, and cannot limit the protection scope of the present invention with this.

Example 1

4.76 g (50 mmol) of anhydrous MgCl ₂ , 75 ml of decane and 16.3 g (125 mmol) of iso-octanol were heated to 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous and transparent solution. To this solution was added 15 mmol of ethyl trimethyl acetate and stirred at 50° C. for 2 hours to dissolve ethyl trimethyl acetate in the solution. The homogeneous solution obtained above was cooled to room temperature and then added dropwise to 150 mL of _TiCl4 maintained at -10 °C within 1 h with stirring. After dropping, the temperature of the mixture was maintained at -10°C for 1 hour, then the temperature was raised to 120°C at a certain rate of temperature increase under stirring, and the temperature was maintained for 2 hours. After the reaction, the generated solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium can be detected in the cleaning solution, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

2L stainless steel polymerization reaction kettle, after being fully replaced by high-purity nitrogen, add 1.0L of hexane and 1.0mL of triethylaluminum with a concentration of 1.0M, add the catalyst prepared above accurately with a syringe, raise the temperature to 75°C, and pass Add hydrogen to make the pressure in the kettle reach 0.28MPa, then feed ethylene to make the total pressure in the kettle reach 0.73MPa (gauge pressure), and polymerize at 80°C for 2 hours. The polymerization results are shown in Table 1.

Example 2

4.76 g (50 mmol) of anhydrous MgCl ₂ , 75 ml of decane and 16.3 g (125 mmol) of isooctyl alcohol were heated to 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. To this solution was added 15 mmol of ethyl chloroacetate and stirred at 50°C for 2 hours to dissolve ethyl chloroacetate in the solution. The entire homogeneous solution obtained above was cooled to room temperature and then added dropwise to 200 mL of _TiCl4 maintained at -15 °C within 1 h with stirring. After completion of the dropwise addition, the temperature of the mixture was maintained at -15°C for 1 hour, then raised to 120°C over 4 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

A stainless steel reaction kettle with a capacity of 2L is fully replaced by high-purity nitrogen, add 1L of hexane and 1.0mL of triethylaluminum with a concentration of 1M, add the catalyst prepared above with a syringe, raise the temperature to 75°C, and pass in hydrogen Make the pressure in the kettle reach 0.28MPa, then feed ethylene to make the total pressure in the kettle reach 0.73MPa (gauge pressure), and polymerize at 80°C for 2 hours. The polymerization results are shown in Table 1.

Example 3

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. To this solution was added 15 mmol of ethyl trichloroacetate and stirred at 50° C. for 2 hours to dissolve ethyl trichloroacetate in the solution. The entire homogeneous solution obtained above was cooled to room temperature and then added dropwise with stirring to 150 mL of _TiCl4 maintained at 0 °C within 1 h. After completion of the dropwise addition, the temperature of the mixture was maintained at 0°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

A stainless steel reaction kettle with a capacity of 2L is fully replaced by high-purity nitrogen, add 1L of hexane and 1.0mL of triethylaluminum with a concentration of 1M, add the catalyst prepared above with a syringe, raise the temperature to 75°C, and pass in hydrogen Make the pressure in the kettle reach 0.28MPa, then feed ethylene to make the total pressure in the kettle reach 0.73MPa (gauge pressure), and polymerize at 80°C for 2 hours. The polymerization results are shown in Table 1.

Example 4

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. To this solution was added 15 mmol of ethyl dimethylphosphonoacetate and stirred at 50° C. for 2 hours to dissolve ethyl dimethylphosphonoacetate in the solution. The entire homogeneous solution obtained above was cooled to room temperature and then added dropwise with stirring to 150 mL of _TiCl4 maintained at 0 °C within 1 h. After completion of the dropwise addition, the temperature of the mixture was maintained at 0°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

A stainless steel reaction kettle with a capacity of 2L is fully replaced by high-purity nitrogen, 1L of hexane and 1.0mL of triethylaluminum with a concentration of 1M are added, and the catalyst prepared above is accurately weighed with a syringe. Hydrogen made the pressure in the kettle reach 0.28MPa, and then ethylene was introduced to make the total pressure in the kettle reach 0.73MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 1.

Example 5

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. To this solution was added 15 mmol of ethyl diacetoacetate and stirred at 50° C. for 2 hours to dissolve ethyl diacetoacetate in the solution. The entire homogeneous solution obtained above was cooled to room temperature and then added dropwise with stirring to 150 mL of _TiCl4 maintained at -10 °C within 1 h. After completion of the dropwise addition, the temperature of the mixture was maintained at -10°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

A stainless steel reaction kettle with a capacity of 2L is fully replaced by high-purity nitrogen, 1L of hexane and 1.0mL of triethylaluminum with a concentration of 1M are added, and the catalyst prepared above is accurately weighed with a syringe. Hydrogen made the pressure in the kettle reach 0.28MPa, and then ethylene was introduced to make the total pressure in the kettle reach 0.73MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 1.

Example 6

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. To this solution was added 15 mmol of ethyl 2-(chloromethoxy)acetate and stirred at 50° C. for 2 hours to dissolve ethyl 2-(chloromethoxy)acetate in the solution. The entire homogeneous solution obtained above was cooled to room temperature and then added dropwise with stirring to 150 mL of _TiCl4 maintained at -10 °C within 1 h. After completion of the dropwise addition, the temperature of the mixture was maintained at -10°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

A stainless steel reaction kettle with a capacity of 2L is fully replaced by high-purity nitrogen, 1L of hexane and 1.0mL of triethylaluminum with a concentration of 1M are added, and the catalyst prepared above is accurately weighed with a syringe. Hydrogen made the pressure in the kettle reach 0.28MPa, and then ethylene was introduced to make the total pressure in the kettle reach 0.73MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 1.

Example 7

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. The entire homogeneous solution obtained above was cooled to room temperature and then added dropwise with stirring to 150 mL of _TiCl4 maintained at -10 °C within 1 h. Then 15 mmol of ethyl trichloroacetate was added to the solution. After completion of the dropwise addition, the temperature of the mixture was maintained at -10°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

A stainless steel reaction kettle with a capacity of 2L is fully replaced by high-purity nitrogen, 1L of hexane and 1.0mL of triethylaluminum with a concentration of 1M are added, and the catalyst prepared above is accurately weighed with a syringe. Hydrogen made the pressure in the kettle reach 0.28MPa, and then ethylene was introduced to make the total pressure in the kettle reach 0.73MPa (gauge pressure). Polymerization was carried out at 80°C for 2 hours. The polymerization results are shown in Table 1.

Example 8

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. The entire homogeneous solution obtained above was cooled to room temperature and then added dropwise with stirring to 150 mL of _TiCl4 maintained at -10 °C within 1 h. Then 15 mmol of ethyl cyanoacetate was added to this solution. After completion of the dropwise addition, the temperature of the mixture was maintained at -10°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization

A stainless steel reaction kettle with a volume of 2L is fully replaced by high-purity nitrogen, 1L of hexane and 1.0mL of triethylaluminum with a concentration of 1M are added, and the catalyst prepared above is accurately weighed with a syringe, the temperature is raised to 75°C, and hydrogen is introduced. Make the pressure in the kettle reach 0.28MPa, then feed ethylene to make the total pressure in the kettle reach 0.73MPa (gauge pressure), and polymerize at 80°C for 2 hours. The polymerization results are shown in Table 1.

Comparative example 1

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. 15 mmol of tetraethoxysilane was added to the solution and stirred at 50° C. for 2 hours to dissolve tetraethoxysilane in the solution. All the homogeneous solutions obtained above were cooled to −10 °C, and then 150 mL of _TiCl4 maintained at −10 °C was added dropwise to the above homogeneous solutions within 1 h while stirring. After completion of the dropwise addition, the temperature of the mixture was maintained at 0°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization is the same as in Example 1, and the polymerization results are shown in Table 1.

What has been described above is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some modifications and improvements can be made without departing from the inventive concept, and these all belong to the scope of the present invention. protected range.

Comparative example 2

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 125° C. and reacted at constant temperature for 3 hours to obtain a homogeneous solution. To this solution was added 15 mmol of ethyl acetate and stirred at 50° C. for 2 hours to dissolve ethyl acetate in the solution. All the homogeneous solutions obtained above were cooled to −10 °C, and then 150 mL of _TiCl4 maintained at −10 °C was added dropwise to the above homogeneous solutions within 1 h while stirring. After completion of the dropwise addition, the temperature of the mixture was maintained at 0°C for 1 hour, then raised to 120°C over 2 hours with stirring, and maintained at this temperature for 2 hours. After 2 hours of reaction, the resulting solid was separated by hot filtration. The solid catalyst is fully washed with decane and hexane respectively until no precipitated titanium compound can be detected in the cleaning liquid, and a solid titanium catalyst component is obtained after drying.

Ethylene polymerization is the same as in Example 1, and the polymerization results are shown in Table 1.

Table 1 Polymerization experiment results

What has been described above is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some modifications and improvements can be made without departing from the inventive concept, and these all belong to the scope of the present invention. protected range.

Claims (10)

1. an internal electron donor of ethylene polymerization Ziegler-Natta catalyst, it is characterized in that: for replacing ethyl acetate compound, it has the structure as described in general formula (I): In the formula: R ₁ , R ₂ and R ₃ are the same or different, respectively selected from hydrogen, methyl, ethyl, C3-C10 alkyl, cycloalkyl, aryl, halogen, alkylphosphono, alkoxy or haloalkoxy. 2. The internal electron donor of ethylene polymerization Ziegler-Natta catalyst according to claim 1, is characterized in that: described substituted ethyl acetate compound is ethyl chloroacetate, ethyl bromoacetate, ethyl iodoacetate, dichloroacetate Ethyl acetate, ethyl dibromoacetate, ethyl diiodoacetate, ethyl trichloroacetate, ethyl tribromoacetate, ethyl triiodoacetate, ethyl trimethylacetate, ethyl cyanoacetate, dimethyl Ethyl phosphonoacetate, ethyl diacetoacetate, ethyl p-toluene acetate, ethyl 2-(chloromethoxy)acetate. 3. A catalyst component comprising the internal electron donor according to claim 1 or 2, characterized in that: the catalyst component comprises: ①Magnesium complexes; ②Titanium compounds; ③Substituted ethyl acetate compounds; The magnesium complex described in component ① is a product obtained by dissolving magnesium halide in a solvent system containing an organic alcohol compound; the organic alcohol compound is a straight chain or branched chain with 1 to 10 carbon atoms. alkyl alcohols, cycloalkanols with 3 to 10 carbon atoms, aromatic alcohols with 7 to 20 carbon atoms, and halogenated organic alcohols; the above alcohols are a single type or a mixture of two or more alcohols; The general formula of the titanium compound described in component ② is Ti(OR) _a X _b , where R is an aliphatic hydrocarbon group or aryl group with C ₁ to C ₁₀ , X is a halogen, a is 0, 1, 2 or 3, b is an integer of 1 to 4, and a+b=3 or 4. 4. The catalyst component according to claim 3, characterized in that: based on each mole of magnesium halide, the organic alcohol compound content is: 0.1-10.0 moles, the ethyl acetate compound content is 0.05-1.0 moles, the titanium compound content 1.0 to 15.0 mol. 5. a preparation method of the catalyst component as claimed in claim 3, the steps are as follows: (1) Dissolving magnesium halide in a solvent system containing an organic alcohol compound, adding an inert diluent, the dissolution temperature is 50-125°C to obtain component ①, adding component ③ to component ① to obtain a reaction solution; ⑵At -24°C~10°C, contact the reaction solution with component ②, and slowly raise the temperature of the mixture to 80~125°C, the solid matter gradually precipitates and forms particles, after a certain period of reaction, remove the unreacted matter and solvent , and washed with an inert diluent to obtain a particle-shaped solid titanium catalyst component. 6. a preparation method of the catalyst component as claimed in claim 3, the steps are as follows: (1) Dissolve magnesium halide in a solvent system containing organic alcohol compounds, add an inert diluent, and dissolve at a temperature of 50-125°C to obtain component ①; (2) At -24°C to 10°C, first contact component ① and component ② for a contact reaction, then add component ③, and slowly raise the temperature of the mixture to 80-125°C, the solids will gradually precipitate and form particles, and react for a certain period of time Afterwards, unreacted substances and solvents are removed, and an inert diluent is used for washing to obtain a particle-shaped solid titanium catalyst component. 7. A catalyst comprising the catalyst component of claim 3, comprising: (1) the catalyst component described in claim 3; (2) Organoaluminum compounds 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 halogen, and 0<n≤3. 8. The catalyst according to claim 7, characterized in that the molar ratio of aluminum in component (2) to titanium in component (1) is 10-1000. 9. The application of the electron donor described in claim 1 or 2 in ethylene polymerization or copolymerization. 10. The application of the catalyst component according to claim 3 or the catalyst according to claim 7 in ethylene polymerization or copolymerization.