Catalyst component for ethylene polymerization, preparation method and system thereof

Abstract

The invention discloses a catalyst component for ethylene polymerization, a preparation method and a system thereof, and belongs to the technical field of catalysts, the catalyst component comprises the following components: a MgX2 compound, a Ti (OR1) nCl4-n compound, a R2OH compound, a Si (OR3) nCl4-n compound and a VOCln compound, the catalyst prepared by the invention is regular in particle form, the particles are not broken in the process of catalyzing ethylene polymerization, the stacking density of ethylene polymerization powder is high, the particle size distribution is concentrated, the activity difference is small during polymerization under high hydrogen partial pressure and low hydrogen partial pressure, the melt index difference of polymers is large, and the catalyst is suitable for a slurry method ethylene polymerization process; the catalyst is especially suitable for a slurry-method double / multi-reactor ethylene polymerization process.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a catalyst component for ethylene polymerization, a preparation method thereof, and a system thereof. Background Art

[0002] With the development of olefin polymerization processes, the catalysts supporting the polymerization processes have also made great progress.

[0003] The Ziegler-Natta type high-efficiency catalyst is a kind of olefin polymerization catalyst, which occupies an important position in the field of olefin polymerization catalysts by virtue of its excellent polymerization performance and mature application technology.

[0004] At present, the preparation methods of Ziegler-Natta type high-efficiency catalysts include the dissolution and precipitation method, that is, first dissolving a magnesium compound in a certain solvent and then precipitating it. For example, Japanese Patent Application Laid-Open No. 54-40293 proposed to dissolve a magnesium compound with a titanate, Japanese Patent Application Laid-Open Nos. 56-811 and 58-83006 proposed to dissolve a magnesium compound with compounds such as alcohols, aldehydes, amines, and carboxylic acids, Japanese Patent Application Laid-Open No. 58-19307 proposed to dissolve a magnesium compound with an organic phosphorus compound, and Japanese Patent Application Laid-Open No. 58-183708 proposed to dissolve a magnesium compound with a mixture of an organic epoxide and an organic phosphorus compound (phosphate ester compounds), etc.

[0005] Although the above-mentioned magnesium compound dissolution methods can all achieve the purpose of dissolving magnesium compounds, there are still a series of deficiencies to be improved. For example, after the catalysts are precipitated from the magnesium compound solutions of Japanese Patent Application Laid-Open Nos. 54-40293, 58-19307, and 58-183708 and used for catalyzing olefin polymerization, their catalytic activities are relatively low, and when the polymerization time is extended, the activities decrease significantly, and the bulk density of the polymer is also relatively low.

[0006] At present, the preparation methods of Ziegler-Natta type high-efficiency catalysts also include the chemical reaction method, that is, preparing a catalyst by using chemical raw materials such as an organometallic magnesium compound, a chlorinating agent, and a transition metal titanium compound. For example, the catalysts disclosed in Chinese Patents CN1158136, CN1299375, and CN1795213. Although the performance of this type of Ziegler-Natta catalyst is easy to modulate, there are generally problems such as poor particle morphology and wide distribution of the obtained catalysts, and some even have a multi-modal distribution, which is not conducive to the long-term stable operation of the polymerization device.

[0007] In view of this, a catalyst component for ethylene polymerization, a preparation method thereof, and a system thereof are designed to solve the above problems. Summary of the Invention

[0008] To solve the problems raised in the above background art, the present invention provides a catalyst component for ethylene polymerization, a preparation method thereof, and a system thereof, which have the characteristics that the prepared catalyst particles have regular morphology, the particles do not break during the ethylene polymerization process, the bulk density of the ethylene polymerization powder is high, the particle size distribution is concentrated, and the activities during polymerization under high hydrogen partial pressure and low hydrogen partial pressure are less different, while the melt indices of the polymers are quite different.

[0009] To achieve the above object, the present invention provides the following technical solution: A catalyst component for ethylene polymerization, comprising the following components:

[0010] MgX2 compound, Ti(OR 1 ) n Cl 4-n compound, R 2 OH compound, Si(OR 3 ) n Cl 4-n compound and VOCl n compound.

[0011] Further, X in the MgX2 compound is chlorine, bromine, or iodine element.

[0012] Further, R in the Ti(OR 1 ) n Cl 4-n compound is a saturated or unsaturated straight-chain, branched-chain, or cyclic hydrocarbon group of C2 - C 1 , and 0 < n ≤ 4. 20

[0013] Further, R in the R 2 OH compound is a straight-chain hydrocarbon group of C2 - C 2 . 20

[0014] Further, R in the Si(OR 3 ) n Cl 4-n compound is a saturated or unsaturated straight-chain, branched-chain, or cyclic hydrocarbon group of C2 - C 3 , and 0 < n ≤ 4. 20

[0015] Further, n in the VOCl n compound is 2 or 3.

[0016] The preparation method of the above-mentioned catalyst component for ethylene polymerization comprises the following steps:

[0017] S1: Under the condition of 80 °C to 200 °C, add 1 mol of MgX2 compound into a mixed solvent formed by 1 mol to 10 mol of Ti(OR 1 ) n Cl 4-n compound and 0.1 mol to 5 mol of R 2 OH compound, stir for 0.5 h to 10 h to accelerate dissolution and form a transparent solution;

[0018] S2: Cool the transparent solution below room temperature, and under the condition of -30 °C to 25 °C, add 1 mol to 10 mol of Si(OR 3 ) n Cl 4-n compound for reaction, and continue to stir for 0.5 h to 8 h after the reaction ends;

[0019] S3: Under the condition of -30 °C to 25 °C, add 0.05 mol to 1 mol of VOCl n compound, heat up to 25 °C to 80 °C, and stir at a constant temperature for 0.5 h to 8 h to obtain a solid catalyst component.

[0020] Furthermore, in the step S1, the reaction temperature is preferably 100 °C to 150 °C, the addition amount of Ti(OR 1 ) n Cl 4-n compound is preferably 2 mol to 5 mol, the addition amount of R 2 OH compound is preferably 0.1 mol to 1 mol, and the stirring time is preferably 2 h to 4 h;

[0021] In step S2, the reaction temperature is preferably -20 °C to 0 °C, the addition amount of Si(OR 3 ) n Cl 4-n compound is preferably 1 mol to 5 mol, and the stirring time is preferably 1 h to 3 h;

[0022] In step S3, the reaction temperature is preferably -20 °C to 0 °C, and the stirring time is preferably 1 h to 3 h.

[0023] The system of a catalyst component for ethylene polymerization described above includes: the catalyst component for ethylene polymerization described above and an AlR'3 organoaluminum compound, and the molar ratio of titanium element in the catalyst component to the AlR'3 organoaluminum compound is 1 to 500.

[0024] Furthermore, R' in the AlR'3 organoaluminum compound is a hydrocarbon group with 1 to 20 carbon atoms.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] The catalyst particles prepared by the present invention have regular morphology, do not break during the ethylene polymerization process, have a high bulk density of the ethylene polymerization powder, a concentrated particle size distribution, and a small difference in activity during polymerization at high and low hydrogen partial pressures, and a large difference in the melt index of the polymer. It is suitable for the slurry process of ethylene polymerization, especially for the slurry double / multi-reactor ethylene polymerization process. Detailed implementation mode

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] The present invention provides the following technical solutions: A catalyst component for ethylene polymerization, comprising the following components:

[0029] MgX2 compound, Ti(OR 1 ) n Cl 4-n compound, R 2 OH compound, Si(OR 3 ) n Cl 4-n compound and VOCl n compound.

[0030] Specifically, X in the MgX2 compound is chlorine, bromine, and iodine elements.

[0031] During implementation, the MgX2 compound is magnesium chloride, magnesium bromide, and magnesium iodide, preferably magnesium chloride.

[0032] Specifically, R in the Ti(OR 1 ) n Cl 4-n compound is a saturated or unsaturated straight-chain, branched-chain, or cyclic hydrocarbon group of C2 to C 1 , where 0 < n ≤ 4. 20 During implementation, the Ti(OR

[0033] ) 1 ) n Cl 4-n compound includes tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, or a mixture of reaction products of titanium tetrachloride and fatty alcohols, preferably tetrabutyl titanate.

[0034] Specifically, R in the R 2 OH compound is a straight-chain hydrocarbon group of C2 to C 2 , where 0 < n ≤ 4. 20 ​

[0035] During implementation, R 2 OH compounds include ethanol, propanol, n-butanol, isobutanol, n-pentanol and its isomers, n-hexanol and its isomers, n-heptanol and its isomers, and n-octanol and its isomers, preferably n-butanol or isobutanol, and most preferably n-butanol.

[0036] Specifically, Si(OR 3 ) n Cl 4-n In the R of the compound 3 is a saturated or unsaturated straight-chain, branched-chain or cyclic hydrocarbon group of C2-C 20 , and 0 < n ≤ 4.

[0037] During implementation, Si(OR 3 ) n Cl 4-n compounds include a mixture of silicon tetrachloride and the reaction product of silicon tetrachloride and fatty alcohol.

[0038] Specifically, n = 2 or 3 in the VOCl n compound.

[0039] A method for preparing a catalyst component for ethylene polymerization includes the following steps:

[0040] S1: Under the condition of 80°C to 200°C, add 1 mol of MgX2 compound to a mixed solvent formed by 1 mol to 10 mol of Ti(OR 1 ) n Cl 4-n compound and 0.1 mol to 5 mol of R 2 OH compound, stir for 0.5 h to 10 h to accelerate dissolution and form a transparent solution;

[0041] S2: Cool the transparent solution to below room temperature, and add 1 mol to 10 mol of Si(OR 3 ) n Cl 4-n compound to react at -30°C to 25°C, and continue to stir for 0.5 h to 8 h after the reaction ends;

[0042] S3: Add 0.05 mol to 1 mol of VOCl n compound at -30°C to 25°C, heat up to 25°C to 80°C, and stir and react at a constant temperature for 0.5 h to 8 h to obtain a solid catalyst component.

[0043] Specifically, in step S1, the reaction temperature is preferably 100°C to 150°C, and Ti(OR 1 ) n Cl4-n The addition amount of the compound is preferably 2 mol to 5 mol, R 2 The addition amount of the ROH compound is preferably 0.1 mol to 1 mol, and the stirring time is preferably 2 h to 4 h;

[0044] In step S2, the reaction temperature is preferably -20°C to 0°C, Si(OR 3 ) n Cl 4-n The addition amount of the compound is preferably 1 mol to 5 mol, and the stirring time is preferably 1 h to 3 h;

[0045] In step S3, the reaction temperature is preferably -20°C to 0°C, and the stirring time is preferably 1 h to 3 h.

[0046] A system of catalyst components for ethylene polymerization, comprising: a catalyst component for ethylene polymerization and an AlR'3 organoaluminum compound, and the molar ratio of titanium element in the catalyst component to the AlR'3 organoaluminum compound is 1 to 500.

[0047] Specifically, R' in the AlR'3 organoaluminum compound is a hydrocarbon group of 1 to 20.

[0048] During implementation, the AlR'3 organoaluminum compound includes AlEt3, Al(iso-Bu)3, Al(n-C6H 13 )3 and Al(n-C8H 17 )3.

[0049] Example 1

[0050] Preparation of the catalyst component:

[0051] Dry a 500 ml reaction kettle, and after fully replacing it with nitrogen, add 5.0 g of anhydrous magnesium chloride, 40 ml of tetrabutyl titanate and 1 ml of n-butanol, and stir and react at 130°C for 3 h to obtain a transparent solution;

[0052] Lower the temperature of the transparent solution to -20°C, add 100 ml of isopentane for dilution, and then slowly dropwise add 27 ml of silicon tetrachloride. During the dropping process, keep the reaction system temperature between -20°C and -15°C. After the dropping is completed, stir and react at -20°C for 1 h, then add 0.3 ml of vanadyl trichloride, stir and react for 1 h, then raise the system temperature to 60°C, stir and react for 2 h, then lower the system temperature to room temperature, stop stirring, stand for 1 h, and press out the supernatant with a lower dip tube;

[0053] Add 200 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, stand for 1 h, and press out the supernatant to complete the first washing of the catalyst, and repeat the washing operation 2 more times;

[0054] Finally, raise the temperature of the system to 40 °C and dry it by purging with nitrogen to obtain solid catalyst powder;

[0055] Test the particle size distribution of the catalyst and calculate the Span value. The results are shown in Table 1;

[0056] Catalyze the ethylene polymerization reaction:

[0057] Add 1 L of hexane, 1 mmol of triethylaluminum, and 10 mg of the above catalyst component to a 2 L stainless steel stirring kettle. Then raise the temperature to 80 °C, add hydrogen to 0.28 MPa, and then maintain the total pressure of the system at 0.73 MPa with ethylene for the polymerization reaction. After 2 h of reaction, stop adding ethylene, cool down, relieve the pressure, weigh the polyethylene powder, calculate the activity of the catalyst, and test the bulk density and melt index of the polyethylene powder. The results are shown in Table 1;

[0058] Sieve the polyethylene powder with a vibrating sieve. The results are shown in Table 2.

[0059] Example 2

[0060] The preparation of the catalyst component is the same as that in Example 1;

[0061] Catalyze the ethylene polymerization reaction:

[0062] Add 1 L of hexane, 1 mmol of triethylaluminum, and 10 mg of the above catalyst component to a 2 L stainless steel stirring kettle. Then raise the temperature to 80 °C, add hydrogen to 0.38 MPa, and then maintain the total pressure of the system at 0.73 MPa with ethylene for the polymerization reaction. After 2 h of reaction, stop adding ethylene, cool down, relieve the pressure, weigh the polyethylene powder, calculate the activity of the catalyst, and test the bulk density and melt index of the polyethylene powder. The results are shown in Table 1;

[0063] Sieve the polyethylene powder with a vibrating sieve. The results are shown in Table 2.

[0064] Example 3

[0065] The preparation of the catalyst component is the same as that in Example 1;

[0066] Catalyze the ethylene polymerization reaction:

[0067] Add 1 L of hexane, 1 mmol of triethylaluminum, and 10 mg of the above catalyst component to a 2 L stainless steel stirring kettle. Then raise the temperature to 80 °C and maintain the total pressure of the system at 0.73 MPa with ethylene for the polymerization reaction. After 2 h of reaction, stop adding ethylene, cool down, relieve the pressure, weigh the polyethylene powder, calculate the activity of the catalyst, and test the bulk density of the polyethylene powder. The results are shown in Table 1;

[0068] The polyethylene powder was screened by a vibrating screen, and the results are shown in Table 2.

[0069] Example 4

[0070] Preparation of the catalyst components:

[0071] The 500 ml reaction kettle was dried, fully replaced with nitrogen, then 5.0 g of anhydrous magnesium chloride, 80 ml of tetrabutyl titanate and 0.5 ml of n-butanol were added, and the mixture was stirred and reacted at 130 °C for 3 h to obtain a transparent solution;

[0072] The temperature of the transparent solution was lowered to -20 °C, 100 ml of isopentane was added for dilution, and then 15 ml of silicon tetrachloride was slowly added dropwise. During the dropwise addition, the temperature of the reaction system was maintained between -20 °C and -15 °C. After the dropwise addition was completed, the mixture was stirred and reacted at -20 °C for 1 h, then 0.5 ml of vanadyl trichloride was added, and the mixture was stirred and reacted for 2 h. Then the temperature of the system was raised to 60 °C, and the mixture was stirred and reacted for 2 h. Then the temperature of the system was lowered to room temperature, the stirring was stopped, and the mixture was allowed to stand for 1 h. The supernatant was pressed out with a lower dip tube;

[0073] At room temperature, 200 ml of anhydrous isopentane was added, and the mixture was stirred for 0.5 h, then the stirring was stopped, and the mixture was allowed to stand for 1 h. The supernatant was pressed out with a lower dip tube to complete the first washing of the catalyst, and the washing operation was repeated 2 times;

[0074] Finally, the temperature of the system was raised to 40 °C, and nitrogen was used for purging and drying to obtain a solid catalyst powder;

[0075] The particle size distribution of the catalyst was tested, and the Span value was calculated. The results are shown in Table 1;

[0076] The catalytic ethylene polymerization reaction was the same as in Example 1.

[0077] Example 5

[0078] The preparation of the catalyst components was the same as in Example 4;

[0079] The catalytic ethylene polymerization reaction was the same as in Example 2.

[0080] Example 6

[0081] The preparation of the catalyst components was the same as in Example 4;

[0082] The catalytic ethylene polymerization reaction was the same as in Example 3.

[0083] Example 7

[0084] Preparation of the catalyst components:

[0085] The 500 ml reaction kettle was dried, fully replaced with nitrogen, then 5.0 g of anhydrous magnesium chloride, 60 ml of tetrabutyl titanate and 2.5 ml of n-butanol were added, and the mixture was stirred and reacted at 140 °C for 2 h to obtain a transparent solution;

[0086] Cool the temperature of the transparent solution to -10°C, add 150 ml of isopentane for dilution, then slowly dropwise add 30 ml of silicon tetrachloride, and keep the temperature of the reaction system between -10°C and -5°C during the dropping process. After the dropping is completed, stir and react at -10°C for 2 h, then add 0.9 ml of vanadium oxychloride, stir and react for 2 h, then raise the temperature of the system to 50°C, stir and react for 3 h, then lower the temperature of the system to room temperature, stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula;

[0087] Add 250 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula to complete the first washing of the catalyst, and repeat the washing operation 2 more times;

[0088] Finally, raise the temperature of the system to 70°C, and blow dry with nitrogen to obtain solid catalyst powder;

[0089] Test the particle size distribution of the catalyst and calculate the Span value. The results are shown in Table 1;

[0090] Catalyze the ethylene polymerization reaction in the same way as in Example 1.

[0091] Example 8

[0092] Prepare the catalyst components in the same way as in Example 7;

[0093] Catalyze the ethylene polymerization reaction in the same way as in Example 2.

[0094] Example 9

[0095] Prepare the catalyst components in the same way as in Example 7;

[0096] Catalyze the ethylene polymerization reaction in the same way as in Example 3.

[0097] Example 10

[0098] Preparation of catalyst components:

[0099] Dry a 500-ml reaction kettle, and after fully displacing it with nitrogen, add 5.0 g of anhydrous magnesium chloride, the reaction product of 40 ml of titanium tetrachloride and butanol (the molar ratio of titanium tetrachloride to butanol is 1:3.9), and 10 ml of n-butanol, and stir and react at 100°C for 4 h to obtain a transparent solution;

[0100] Cool the temperature of the transparent solution to -0°C, add 120 ml of isopentane for dilution, and then slowly dropwise add 31 ml of silicon tetrachloride. During the dropping process, maintain the reaction system temperature between -5°C and 0°C. After the dropping is completed, stir and react at -2°C for 1 h. Subsequently, add 0.4 ml of vanadyl trichloride and stir and react for 2 h. Then raise the system temperature to 60°C and stir and react for 2 h. Then lower the system temperature to room temperature, stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula;

[0101] Add 200 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula to complete the first washing of the catalyst. Repeat the washing operation 2 more times;

[0102] Finally, raise the system temperature to 40°C and dry it by purging with nitrogen to obtain solid catalyst powder;

[0103] Test the particle size distribution of the catalyst and calculate the Span value. The results are shown in Table 1;

[0104] The ethylene polymerization reaction is the same as in Example 1.

[0105] Example 11

[0106] The preparation of the catalyst components is the same as in Example 10;

[0107] The ethylene polymerization reaction is the same as in Example 2.

[0108] Example 12

[0109] The preparation of the catalyst components is the same as in Example 10;

[0110] The ethylene polymerization reaction is the same as in Example 3.

[0111] Example 13

[0112] Preparation of the catalyst components:

[0113] Dry a 500 ml reaction kettle, and after fully displacing it with nitrogen, add 5.0 g of anhydrous magnesium chloride, 80 ml of the reaction product of titanium tetrachloride and butanol (the molar ratio of titanium tetrachloride to butanol is 1:3.8), and 20 ml of n-butanol. Stir and react at 150°C for 3 h to obtain a transparent solution;

[0114] Cool the temperature of the transparent solution to -5°C, add 120 ml of isopentane for dilution, and then slowly dropwise add 54 ml of silicon tetrachloride. During the dropping process, maintain the reaction system temperature between -5°C and 0°C. After the dropping is completed, stir and react at -2°C for 1 h. Subsequently, add 0.7 g of vanadyl dichloride and stir and react for 2 h. Then raise the system temperature to 60°C and stir and react for 2 h. Then lower the system temperature to room temperature, stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula;

[0115] Add 200 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, let stand for 1 h, and press out the supernatant with a lower cannula to complete the first washing of the catalyst. Repeat the washing operation 2 more times;

[0116] Finally, raise the temperature of the system to 40 °C and dry it by purging with nitrogen to obtain a solid catalyst powder;

[0117] Test the particle size distribution of the catalyst and calculate the Span value. The results are shown in Table 1;

[0118] Catalyze the ethylene polymerization reaction as in Example 1.

[0119] Example 14

[0120] Prepare the catalyst components as in Example 13;

[0121] Catalyze the ethylene polymerization reaction as in Example 2.

[0122] Example 15

[0123] Prepare the catalyst components as in Example 13;

[0124] Catalyze the ethylene polymerization reaction as in Example 3.

[0125] Example 16

[0126] Preparation of catalyst components:

[0127] Dry a 500 ml reaction kettle, fully displace it with nitrogen, then add 5.0 g of anhydrous magnesium chloride, 40 ml of tetrabutyl titanate, and 1 ml of n-butanol, and stir and react at 130 °C for 3 h to obtain a transparent solution;

[0128] Lower the temperature of the transparent solution to -20 °C, add 120 ml of isopentane for dilution, then slowly dropwise add 27 ml of silicon tetrachloride, and keep the temperature of the reaction system between -20 °C and -15 °C during the dropping process. After the dropping is completed, stir and react at -20 °C for 1 h, then add 0.4 g of vanadyl dichloride, stir and react for 1 h, then raise the temperature of the system to 60 °C, stir and react for 2 h, then lower the temperature of the system to room temperature, stop stirring, let stand for 1 h, and press out the supernatant with a lower cannula;

[0129] Add 200 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, let stand for 1 h, and press out the supernatant with a lower cannula to complete the first washing of the catalyst. Repeat the washing operation 2 more times;

[0130] Finally, raise the temperature of the system to 40 °C and dry it by purging with nitrogen to obtain a solid catalyst powder;

[0131] The particle size distribution of the catalyst was tested, and the Span value was calculated. The results are shown in Table 1;

[0132] The ethylene polymerization reaction was the same as in Example 1.

[0133] Example XVII

[0134] The preparation of the catalyst components was the same as in Example XVI;

[0135] The ethylene polymerization reaction was the same as in Example 2.

[0136] Example XVIII

[0137] The preparation of the catalyst components was the same as in Example XVI;

[0138] The ethylene polymerization reaction was the same as in Example 3.

[0139] Example XIX

[0140] Preparation of catalyst components:

[0141] The 500 ml reactor was dried, fully replaced with nitrogen, then 5.0 g of anhydrous magnesium chloride, 40 ml of tetrabutyl titanate and 1 ml of n-butanol were added, and the mixture was stirred at 130 °C for 3 h to obtain a transparent solution;

[0142] The temperature of the transparent solution was lowered to -20 °C, diluted with 120 ml of isopentane, and then a mixture of 27 ml of silicon tetrachloride and ethanol (molar ratio of silicon tetrachloride to ethanol was 3.9) was slowly added dropwise. During the addition, the temperature of the reaction system was maintained between -20 °C and -15 °C. After the addition was completed, the mixture was stirred at -20 °C for 1 h, then 0.4 ml of vanadyl trichloride was added and stirred for 1 h. Then the temperature of the system was raised to 60 °C and stirred for 2 h. Then the temperature of the system was lowered to room temperature, stirring was stopped, and the mixture was allowed to stand for 1 h. The supernatant was pressed out with a lower plug tube;

[0143] At room temperature, 200 ml of anhydrous isopentane was added, stirred for 0.5 h, then stirring was stopped, allowed to stand for 1 h, and the supernatant was pressed out with a lower plug tube to complete the first washing of the catalyst. The washing operation was repeated 2 more times;

[0144] Finally, the temperature of the system was raised to 40 °C and dried by purging with nitrogen to obtain solid catalyst powder;

[0145] The particle size distribution of the catalyst was tested, and the Span value was calculated. The results are shown in Table 1;

[0146] The ethylene polymerization reaction was the same as in Example 1.

[0147] Example XX

[0148] The preparation of the catalyst components was the same as in Example XIX;

[0149] The ethylene polymerization reaction was carried out in the same manner as in Example 2.

[0150] Example 21

[0151] The catalyst component was prepared in the same manner as in Example 19;

[0152] The ethylene polymerization reaction was carried out in the same manner as in Example 3.

[0153] Example 22

[0154] Preparation of catalyst component:

[0155] A 500 ml reaction kettle was dried, fully replaced with nitrogen, then 5.0 g of anhydrous magnesium chloride, 40 ml of tetrabutyl titanate and 0.6 ml of ethanol were added, and the mixture was stirred and reacted at 130 °C for 3 h to obtain a transparent solution;

[0156] The temperature of the transparent solution was lowered to -20 °C, 100 ml of isopentane was added for dilution, then 27 ml of silicon tetrachloride was slowly added dropwise, and the temperature of the reaction system was maintained between -20 °C and -15 °C during the addition. After the addition was completed, the mixture was stirred and reacted at -20 °C for 1 h, then 0.3 ml of vanadyl trichloride was added, and the mixture was stirred and reacted for 1 h. Then the temperature of the system was raised to 60 °C, and the mixture was stirred and reacted for 2 h. Then the temperature of the system was lowered to room temperature, the stirring was stopped, and the mixture was allowed to stand for 1 h. The supernatant was pressed out with a lower inserting tube;

[0157] At room temperature, 200 ml of anhydrous isopentane was added, and the mixture was stirred for 0.5 h, then the stirring was stopped, and the mixture was allowed to stand for 1 h. The supernatant was pressed out with a lower inserting tube to complete the first washing of the catalyst, and the washing operation was repeated 2 more times;

[0158] Finally, the temperature of the system was raised to 40 °C, and the system was dried by purging with nitrogen to obtain solid catalyst powder;

[0159] The particle size distribution of the catalyst was tested, and the Span value was calculated. The results are shown in Table 1;

[0160] The ethylene polymerization reaction was carried out in the same manner as in Example 1.

[0161] Example 23

[0162] The catalyst component was prepared in the same manner as in Example 22;

[0163] The ethylene polymerization reaction was carried out in the same manner as in Example 2.

[0164] Example 24

[0165] The catalyst component was prepared in the same manner as in Example 22;

[0166] The ethylene polymerization reaction was carried out in the same manner as in Example 3.

[0167] Comparative Example 1

[0168] Preparation of catalyst components:

[0169] Dry a 500 ml reactor, fully displace it with nitrogen, then add 5.0 g of anhydrous magnesium chloride, 40 ml of tetrabutyl titanate and 1 ml of n-butanol, and stir and react at 130 °C for 3 h to obtain a transparent solution;

[0170] Cool the temperature of the transparent solution to -20 °C, add 120 ml of isopentane for dilution, then slowly dropwise add 27 ml of titanium tetrachloride, and keep the temperature of the reaction system between -20 °C and -15 °C during the dropping process. After the dropping is completed, stir and react at -20 °C for 1 h, then add 0.4 ml of vanadium oxychloride, stir and react for 1 h, then raise the temperature of the system to 60 °C, stir and react for 2 h, then lower the temperature of the system to room temperature, stop stirring, let it stand for 1 h, and press out the supernatant with a lower dip tube;

[0171] Add 200 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, let it stand for 1 h, and press out the supernatant with a lower dip tube to complete the first washing of the catalyst, and repeat the washing operation 2 more times;

[0172] Finally, raise the temperature of the system to 40 °C, and dry it by purging with nitrogen to obtain a solid catalyst powder;

[0173] Test the particle size distribution of the catalyst and calculate the Span value. The results are shown in Table 1;

[0174] The ethylene polymerization reaction is the same as in Example 1.

[0175] Comparative Example 2

[0176] The preparation of the catalyst components is the same as in Comparative Example 1;

[0177] The ethylene polymerization reaction is the same as in Example 2.

[0178] Comparative Example 3

[0179] The preparation of the catalyst components is the same as in Comparative Example 1;

[0180] The ethylene polymerization reaction is the same as in Example 3.

[0181] Comparative Example 4

[0182] Preparation of catalyst components:

[0183] Dry a 500 ml reactor, fully displace it with nitrogen, then add 5.0 g of anhydrous magnesium chloride and 25 ml of n-butanol, and stir and react at 110 °C for 3 h to obtain a transparent solution;

[0184] Cool the temperature of the transparent solution to -20°C, add 120 ml of isopentane for dilution, and then slowly dropwise add 27 ml of silicon tetrachloride. During the dropping process, maintain the reaction system temperature between -20°C and -15°C. After the dropping is completed, stir and react at -20°C for 1 h. Subsequently, add 0.4 ml of vanadyl trichloride and stir and react for 1 h. Then raise the system temperature to 60°C and stir and react for 2 h. Then lower the system temperature to room temperature, stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula;

[0185] Add 200 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula to complete the first washing of the catalyst. Repeat the washing operation 2 more times;

[0186] Finally, raise the system temperature to 40°C and dry it by purging with nitrogen to obtain a solid catalyst powder;

[0187] Test the particle size distribution of the catalyst and calculate the Span value. The results are shown in Table 1;

[0188] The ethylene polymerization reaction is the same as in Example 1.

[0189] Comparative Example 5

[0190] The preparation of the catalyst components is the same as in Comparative Example 4;

[0191] The ethylene polymerization reaction is the same as in Example 2.

[0192] Comparative Example 6

[0193] The preparation of the catalyst components is the same as in Comparative Example 4;

[0194] The ethylene polymerization reaction is the same as in Example 3.

[0195] Comparative Example 7

[0196] Preparation of the catalyst components:

[0197] Dry a 500 ml reaction kettle, and after fully displacing it with nitrogen, add 5.0 g of anhydrous magnesium chloride, 40 ml of tetrabutyl titanate, and 1 ml of n-butanol. Stir and react at 130°C for 3 h to obtain a transparent solution;

[0198] Cool the temperature of the transparent solution to -20°C, add 100 ml of isopentane for dilution, and then slowly dropwise add 27 ml of silicon tetrachloride. During the dropping process, maintain the reaction system temperature between -20°C and -15°C. After the dropping is completed, stir and react at -20°C for 1 h. Then raise the system temperature to 60°C and stir and react for 2 h. Then lower the system temperature to room temperature, stop stirring, let it stand for 1 h, and press out the supernatant with a lower cannula;

[0199] Add 200 ml of anhydrous isopentane at room temperature, stir for 0.5 h, then stop stirring, let stand for 1 h, and press out the supernatant with a lower cannula to complete the first washing of the catalyst. Repeat the washing operation 2 more times;

[0200] Finally, raise the temperature of the system to 40 °C and dry it by purging with nitrogen to obtain a solid catalyst powder;

[0201] Test the particle size distribution of the catalyst and calculate the Span value. The results are shown in Table 1;

[0202] The ethylene polymerization reaction is the same as in Example 1.

[0203] Comparative Example 8

[0204] The preparation of the catalyst components is the same as in Comparative Example 7;

[0205] The ethylene polymerization reaction is the same as in Example 2.

[0206] Comparative Example 9

[0207] The preparation of the catalyst components is the same as in Comparative Example 7;

[0208] The ethylene polymerization reaction is the same as in Example 3.

[0209] Table 1 is as follows:

[0210] Table 1: Performance of the catalyst

[0211]

[0212] In the table, D(50) represents the average particle size of the catalyst, Span represents the particle size distribution width of the catalyst, MI represents the melt index of polyethylene under a load of 2.16, BD represents the bulk density of the polyethylene powder, and --- represents that the melt index is too small to be measured;

[0213] The particle size of the polymer powder is measured by a vibrating sieve with a sieve standard of GB / T 6003.1-2012;

[0214] The particle size distribution of the catalyst is measured by a MASTERSIZE laser particle size and shape analyzer, using n-hexane as the dispersant, with a measurement range of 0.02 - 2000 μm. Among them, Span is [(particle size at 90% cumulative particle size) - (particle size at 10% cumulative particle size)] / (particle size at 50% cumulative particle size), and 10% / 50% / 90% represents the cumulative particle size indicating the particle size limit, and the cumulative amount of particles at the limit of 10% / 50% / 90% is greater than this particle size limit;

[0215] The catalyst activity is expressed by the weight of the resin obtained per gram of the catalyst component;

[0216] The melt index (MI) of the polymer was measured using a CEAST 6932 melt indexer in accordance with ASTM-D 1238 standard by an Italian company CEAST, with a load of 2.16 kg.

[0217] The bulk density (BD) of the polymer powder was determined by the test method for apparent density, volume factor and pourability of plastics (ASTM D1895).

[0218] It can be seen from Table 1 that compared with the comparative example, the catalyst of this application has higher activity, and the bulk density of the polyethylene powder is basically 0.40 g / mL, which is significantly higher than that of the comparative example. In addition, when the catalyst of this application polymerizes at different hydrogen partial pressures, for example, the hydrogen pressure in Example 1 is 0.28 MPa, the hydrogen pressure in Example 2 is 0.38 MPa, and no hydrogen is added in Example 3, the change range of the activity is relatively small, and the relative change of the melt index is relatively large, indicating that the hydrogen regulation performance of the catalyst of this application is better than that of the catalyst in the comparative example.

[0219] Table 2 is as follows:

[0220] Table 2: Screening results of polyethylene powder

[0221]

[0222]

[0223] It can be seen from Table 2 that the particle size distribution of the polyethylene powder prepared by the catalyst of the present invention is relatively concentrated, basically concentrated between 500 - 75 μm, accounting for more than 99 wt%, which is better than the catalyst in the comparative example. In addition, when the catalyst of this application polymerizes at different hydrogen partial pressures, for example, the hydrogen pressure in Example 1 is 0.28 MPa, the hydrogen pressure in Example 2 is 0.38 MPa, and no hydrogen is added in Example 3, although the activity of the catalyst changes, the change of the particle size distribution of the polyethylene powder is relatively small, indicating that during the process of catalyzing ethylene polymerization, the catalyst particles do not break and adhere.

[0224] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A catalyst component for ethylene polymerization, characterized in that, It comprises the following components: MgX2 compounds, Ti(OR 1 ) n Cl 4-n compounds, R 2 OH compounds, Si(OR 3 ) n Cl 4-n compounds and VOCl n compounds.

2. The catalyst component for ethylene polymerization according to claim 1, characterized in that: In the MgX2 compound, X is chlorine, bromine or iodine element.

3. The catalyst component for ethylene polymerization according to claim 2, characterized in that: The Ti(OR 1 ) n Cl 4-n R in the compound 1 C2~C 20 Saturated or unsaturated straight chain, branched chain or cyclic chain hydrocarbon group, 0 <n≤4。 4. A catalyst component for ethylene polymerization according to claim 3, characterized in that: The R 2 in the R 2 OH compound is a straight-chain hydrocarbon group having 2 to 20 carbon atoms.

5. A catalyst component for ethylene polymerization according to claim 4, characterized in that: The Si(OR 3 ) n Cl 4-n R in the compound 3 C2~C 20 Saturated or unsaturated straight chain, branched chain or cyclic chain hydrocarbon group, 0 <n≤4。 6. The catalyst component for ethylene polymerization according to claim 5, wherein: The VOCl n compound has n = 2 or 3.

7. A method for preparing a catalyst component for ethylene polymerization according to claim 6, characterized in that, It comprises the following steps: S1: Under the condition of 80 °C to 200 °C, add 1 mol of MgX2 compound into a mixed solvent formed by 1 mol to 10 mol of Ti(OR 1 ) n Cl 4-n compound and 0.1 mol to 5 mol of R 2 OH compound, stir for 0.5 h to 10 h to accelerate dissolution and form a transparent solution; S2: Cool the transparent solution to below room temperature, and add 1 mol to 10 mol of Si(OR 3 ) n Cl 4-n compound for reaction. After the reaction ends, continue stirring for 0.5 h to 8 h; S3: Add 0.05 mol to 1 mol of VOCl compound under the condition of -30°C to 25°C, heat up to 25°C to 80°C, and carry out constant-temperature stirring reaction for 0.5 h to 8 h to obtain a solid catalyst component. n ​ 8. A preparation method of a catalyst component for ethylene polymerization according to claim 7, characterized in that: In the step S1, the reaction temperature is preferably 100 °C to 150 °C, and the addition amount of the Ti(OR 1 ) n Cl 4-n compound is preferably 2 mol to 5 mol, the addition amount of the R 2 OH compound is preferably 0.1 mol to 1 mol, and the stirring time is preferably 2 h to 4 h; In step S2, the reaction temperature is preferably -20°C to 0°C, and the addition amount of Si(OR 3 ) n Cl 4-n compound is preferably 1 mol to 5 mol, and the stirring time is preferably 1 h to 3 h; In step S3, the reaction temperature is preferably -20°C to 0°C, and the stirring time is preferably 1 h to 3 h.

9. A system of catalyst components for ethylene polymerization according to claim 8, characterized in that, It includes: A catalyst component for ethylene polymerization and an AlR'3 organoaluminum compound as described in claim 8, and the molar ratio of titanium element in the catalyst component to the AlR'3 organoaluminum compound is 1 to 500.

10. A system of catalyst components for ethylene polymerization according to claim 9, characterized in that, In the AlR'3 organoaluminum compound, R' is a hydrocarbon group of 1 to 20.

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