A composite support type olefin polymerization catalyst, its preparation method and application

Abstract

The present invention discloses a composite carrier type olefin polymerization catalyst, its preparation method and application. The present invention provides a completely new technical solution for a MgCl2 / SiO2 composite carrier for polyolefin catalysts. Moreover, during the catalyst preparation process, the amount of titanium tetrachloride is further reduced by adding alkoxytitanium chloride compounds, effectively reducing the pollution brought by titanium tetrachloride to the environment. Additionally, by using three or more different types of electron donor compounds, a method for improving the hydrogen response sensitivity and copolymerization ability of traditional Ziegler-Natta catalysts is provided, so that the catalyst has high activity, high copolymerization property and high hydrogen response sensitivity during olefin polymerization, which can expand the application range of the catalyst and enable the production of some high-value-added polyolefin products.

Description

Technical Field

[0001] The present invention relates to the technical field of polymerization catalysts, and particularly relates to a composite support type olefin polymerization catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Due to their excellent cost performance, polyolefins are widely used in various aspects of people's daily life, medical and health care, aerospace, industry and agriculture, etc. These polyolefin products with excellent properties are closely related to the catalysts used. In the field of polyolefin catalysts, especially in the fields of polyethylene and polypropylene, since the Japanese Mitsui Chemicals patent JP1031698 and the Italian Montecatini patent GB1286867A disclosed that magnesium chloride supported titanium tetrachloride is a highly active Ziegler-Natta catalyst, it has greatly promoted the development of supported catalysts for polyolefins, and at the same time, it has continuously accelerated the industrialization and application promotion process of polyolefin products. After years of development, at present, the magnesium chloride supported Ziegler-Natta catalyst is still the main catalyst in the polyolefin industry, and now magnesium chloride-containing carriers can be prepared by many different methods. The first method is to first react magnesium chloride with an alcohol to form a magnesium chloride alcoholate solution, and then mix it with an immiscible low-viscosity inert liquid in a ratio such that the molten adduct forms a dispersed phase, and then the mixture is subjected to turbulent flow to obtain an emulsion, and then the emulsion enters a paraffinic solvent frozen to -20 to -30 °C through a capillary tube 50 to 100 times longer than its inner diameter to obtain spherical magnesium chloride carriers, and finally the spherical magnesium chloride carriers are reacted with titanium tetrachloride to remove the alcohol in the carriers and at the same time load the titanium active component on the surface of the magnesium chloride carriers. However, in the related technology, the alcohol and titanium halide must be in excess, the preparation process is relatively complex, and a large amount of titanium-containing acidic waste liquid is generated, resulting in a relatively high production cost of the catalyst. The second method is a one-step preparation process, that is, using ethoxymagnesium, alkylmagnesium, magnesium powder, etc. as raw materials, and then treating them with an electron donor and a titanium halide compound to obtain a particulate catalyst. This preparation process is relatively simple, but due to the relatively high price of raw materials such as ethoxymagnesium or alkylmagnesium used, the preparation cost of the catalyst is high, and it is relatively difficult to control the particle morphology of the catalyst.

[0003] Another main type of industrial load, the catalytic Ziegler-Natta catalyst, is a composite support catalyst. That is, magnesium halide is mixed with spherical or quasi-spherical silica gel to form a composite support, and then a composite support catalyst is prepared through reactions with electron donor compounds, titanium compounds, etc. for olefin polymerization. Typical industrial composite support catalysts are the M-1 catalyst and UCAT-J catalyst used in the UNIPOL gas-phase polyethylene process. The typical preparation method of M-1 is to first dissolve titanium compounds and magnesium compounds in a tetrahydrofuran solution to prepare a mother liquor, and then mix and react the mother liquor with silica gel treated with alkyl aluminum and an electron donor to load the active components onto the silica gel. Then, it is reductively treated with diethylaluminum chloride and tri-n-hexylaluminum and dried to obtain the catalyst. However, the activity of the catalyst prepared by this method is generally about 3 - 7 kgPE / gCat, the catalyst activity is low, and the active components are unevenly distributed on the support. The repeatability of the catalyst preparation process is poor, the catalyst activity, polymer particle morphology, and particle size distribution are not very ideal, and the content of polymer fines is high. The UCAT-J catalyst is to reduce TiCl4 to TiCl3 with magnesium powder in an electron donor solution, then add MgCl2 to the solution to adjust the Mg / Ti molar ratio, and then add silica gel to the above mother liquor to form a heterogeneous solution, which is then spray-dried to obtain a solid catalyst. Finally, the above solid catalyst is mixed with mineral oil containing alkyl aluminum to obtain a slurry catalyst. The activity of this catalyst is higher than 20 kgPE / gCat, and the catalyst activity is relatively high. However, the catalyst preparation process is relatively complex and the cost is relatively high.

[0004] Another type is that a composite support is prepared by spray-drying a magnesium halide solution and silica, and then a titanium compound and an internal electron donor, such as mono- and di-fatty acid esters, mono- and di-aromatic acid esters, diether compounds, etc., are loaded on the support. Finally, a propylene polymerization or copolymerization catalyst is obtained through washing and drying. However, this catalyst requires titanium loading at low temperature during the preparation process, and a large amount of titanium tetrachloride is required during the titanium loading process. Equipment such as spray drying is required during the catalyst preparation process, and the investment cost is relatively high. This not only increases the energy consumption and material consumption during the catalyst production process, but also pollutes the environment and poses hazards to production personnel. Summary of the Invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems in the prior art. To this end, the object of the present invention is to provide a composite support type olefin polymerization catalyst, its preparation method and application. This catalyst system has high copolymerization property, high activity and high hydrogen response sensitivity, and the obtained polyolefin products have good morphology, uniform particles and high bulk density; in addition, by adding three or more kinds of composite electron donors in the catalyst preparation, polyolefin resins with adjustable molecular weight and molecular weight distribution are produced, thereby improving the product performance, improving the processability of the resin and broadening the application fields of the products.

[0006] In order to achieve the above object, the technical solutions adopted by the present invention are as follows:

[0007] In the first aspect of the present invention, a composite support type olefin polymerization catalyst is proposed, which includes a MgCl2-porous silica composite support, a titanium-containing transition metal active ingredient supported on the composite support, and an electron donor compound modifier; the electron donor compound includes at least three of silane compounds, phthalate compounds, diether compounds, succinate compounds, spiro-substituted succinate compounds.

[0008] In some embodiments of the present invention, the content of the electron donor compound in the composite support type olefin polymerization catalyst is 0.10 wt% to 10.00 wt%.

[0009] In some embodiments of the present invention, the Ti content in the composite support type olefin polymerization catalyst is 1.00 wt% to 5.00 wt%.

[0010] In some embodiments of the present invention, the Cl content in the composite support type olefin polymerization catalyst is 14.00 wt% to 34.00 wt%.

[0011] In some embodiments of the present invention, the Mg content in the composite support type olefin polymerization catalyst is 1.00 wt% to 7.00 wt%.

[0012] In some embodiments of the present invention, in the MgCl2-porous silica composite support, the mass ratio of MgCl2 to porous silica is 1:(3 - 10).

[0013] In some embodiments of the present invention, the titanium-containing transition metal includes titanium tetrachloride, titanium tetrahydrofuran chloride, titanium triisopropoxide chloride, diisopropoxide titanium dichloride, etc.

[0014] In some embodiments of the present invention, the electron donor compound is selected from at least three of the following compounds:

[0015]

[0016] Among them, in the silanes, R1 and R2 are each independently selected from C1-C6 hydrocarbon groups, piperidyl, pyrrolyl, glycidyl etheroxy group, thiocyanato group, isocyanate group, and R3 and R4 are each independently selected from C1-C6 hydrocarbon groups, alkoxy groups, amino groups, etc.; in the phthalates, R1 and R2 are each independently selected from C1-C6 hydrocarbon groups, and R3 and R4 are each independently selected from hydrogen group, methyl group or bromo group; in the diether compounds, R1 and R2 are each independently selected from C3-C6 hydrocarbon groups; in the succinate esters, R1 and R2 are each independently selected from hydrogen group and C1-C8 hydrocarbon groups, and R3 and R4 are each independently selected from C1-C6 hydrocarbon groups; in the spiro-substituted succinate esters, R1 and R2 are each independently selected from C1-C6 hydrocarbon groups.

[0017] In some embodiments of the present invention, the silane compounds include at least one of isobutyltriethoxysilane, tetrabutoxysilane, methyltriethoxysilane, methyltriacetoxysilane, methyltriacetoxysilane, 3-methacryloyloxytriethoxysilane, 3-methacryloyloxymethyldiethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane; the phthalate compounds include at least one of dibutyl phthalate, diisobutyl phthalate, dicyclohexyl phthalate, diisooctyl phthalate, dineopentyl phthalate; the diether compounds include at least one of 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2,2-phenyl-1,3-dimethoxypropane, 2--phenyl-2-isopropyl--1,3-dimethoxypropane, 2,2-cyclopentyl-1,3-dimethoxypropane; the succinate ester compounds include at least one of diethyl 2,3-diisopropylsuccinate, diethyl 2,3-diisobutylsuccinate, dimethyl 2,3-diisopropylsuccinate, dimethyl 2,3-diisobutylsuccinate; the spiro-substituted succinate ester compounds include at least one of spiro-substituted butyl succinate, spiro-substituted isobutyl succinate.

[0018] In the second aspect of the present invention, a method for preparing the composite carrier type olefin polymerization catalyst is provided, which includes the following steps:

[0019] S1: Under an inert atmosphere, after reacting an alkane solvent, anhydrous magnesium chloride, an organic alcohol and an alkoxytitanium chloride compound, a donor compound is added and the reaction is continued to obtain a first reactant;

[0020] S2: Adding silica gel to the first reactant for reaction to obtain a second reactant;

[0021] S3: Add an alkane to the second reactant, dropwise add a titanium tetrachloride solution at least twice for reaction, filter off the upper liquid, and then continue to dropwise add n-heptane and the titanium tetrachloride solution for reaction to obtain the composite support type olefin polymerization catalyst described above.

[0022] In some embodiments of the present invention, the dosage of the alkane solvent is 40 mL / g to 80 mL / g of anhydrous magnesium chloride.

[0023] In some embodiments of the present invention, the molar ratio of the organic alcohol to the anhydrous magnesium chloride is (2.0 - 6.0):1.

[0024] In some embodiments of the present invention, the molar ratio of the alkoxytitanium chloride compound to the anhydrous magnesium chloride is (0.05 - 0.1):1.

[0025] In some embodiments of the present invention, the addition amount of the electron donor compound is 0.01 - 0.5 mol / mol of magnesium.

[0026] In some embodiments of the present invention, the alkane solvent includes n-heptane, n-octane, n-decane, etc.

[0027] In some embodiments of the present invention, the organic alcohol includes at least one of C2 - C8 alcohols; preferably n-butanol; the molar ratio of the n-butanol to the anhydrous magnesium chloride is (3.0 - 4.5):1.

[0028] In some embodiments of the present invention, the alkoxytitanium chloride compound includes at least one of titanium tetrahydrofuran chloride, titanium triisopropoxide chloride, and titanium diisopropoxide dichloride.

[0029] In some embodiments of the present invention, S1: Under an inert atmosphere, react an alkane solvent, anhydrous magnesium chloride, an organic alcohol, and an alkoxytitanium chloride compound at 60°C to 85°C for 3.0 h to 5.0 h, then add an electron donor compound and continue to react for 0.5 h to 2.0 h to obtain a first reactant.

[0030] In some embodiments of the present invention, the reaction temperature of S2 is 30°C to 70°C, and the reaction time is 2 h to 5 h.

[0031] In some embodiments of the present invention, the mass ratio of the silica gel to the anhydrous magnesium chloride is (2 - 15):1; preferably (3 - 10):1.

[0032] In some embodiments of the present invention, the silica gel is silica gel treated by activation; the activation treatment includes activating at 200°C for 4 h in a muffle furnace, then activating at 600°C for 4 h and using it under the protection of an inert gas.

[0033] In some embodiments of the present invention, in S3, the amount of titanium tetrachloride solution added for the first time is 1.0 - 3.0 mol / mol of magnesium.

[0034] In some embodiments of the present invention, in S3, the amount of titanium tetrachloride solution added for the second time is 1.0 - 3.0 mol / mol of magnesium.

[0035] In some embodiments of the present invention, in S3, after the first addition of titanium tetrachloride solution and reaction at 10°C - 35°C for 0.1 h - 2.0 h, the temperature is further raised to 60°C - 95°C and the reaction continues for 1.0 h - 3.0 h.

[0036] In some embodiments of the present invention, in S3, the second addition of titanium tetrachloride solution reacts at 80°C - 90°C for 1.0 h - 5.0 h.

[0037] In some embodiments of the present invention, the preparation method of the composite carrier type olefin polymerization catalyst further includes a step of purifying the second reactant; the purification includes washing the second reactant with n - hexane at 50°C - 80°C, and then drying it with high - purity nitrogen at 70°C - 90°C.

[0038] In some embodiments of the present invention, the preparation method of the composite carrier type olefin polymerization catalyst further includes a step of purifying the reaction product of S3; the purification includes washing the reactant of S3 with n - hexane at 50°C - 80°C, and then drying it with high - purity nitrogen at 80°C - 120°C.

[0039] According to the third aspect of the present invention, there is provided an application of the composite carrier type olefin polymerization catalyst in the preparation of polyolefins.

[0040] In some embodiments of the present invention, the polyolefin includes any one of polyethylene and polypropylene.

[0041] The beneficial effects of the present invention are as follows:

[0042] The present invention provides a brand - new technical solution for the MgCl2 / SiO2 composite carrier for polyolefin catalysts. Moreover, during the catalyst preparation process, the addition of alkoxy titanium chloride further reduces the amount of titanium tetrachloride used, and at the same time helps to improve the hydrogen response sensitivity of the catalyst, effectively reducing the environmental pollution caused by titanium tetrachloride. More importantly, the present invention uses three or more different types of electron donor compounds to provide a method for improving the hydrogen response sensitivity and copolymerization ability of traditional Ziegler - Natta catalysts, so that the catalyst has high activity, high copolymerization ability and high hydrogen response sensitivity during olefin polymerization, which can expand the application range of the catalyst to produce some high - value - added polyolefin products (such as high - flow polyolefin products, high - impact polyolefin products, etc.). Description of the Drawings

[0043] Figure 1 This is the SEM image of the composite support type olefin polymerization catalyst in Example 1 of the present invention. Detailed Description of the Invention

[0044] The content of the present invention will be further described in detail through specific examples below. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing technical methods. Unless otherwise specified, the test or measurement methods are all conventional methods in the art.

[0045] The catalyst composition in the examples or comparative examples was determined according to the following method:

[0046] (1) A certain amount of the catalyst sample was extracted with heptane and sulfuric acid solution. After the obtained extract was filtered, the aqueous layer

[0047] was used for the determination of Ti, where the Ti content was analyzed by the absorbance method;

[0048] (2) The particle size and particle size distribution of the catalyst were determined using a MAS-TERSIZE2000 particle size distribution analyzer produced by Malvern Instruments Ltd. in the UK. n-Hexane was used as the dispersant, and the measurement range was 0.02 - 2,000.00 μm. The degree of particle size distribution of the catalyst was expressed by SPAN = (D 90 -D 10 ) / D 50 .

[0049] The performance indexes of each polymer in the examples or comparative examples were determined according to the following method.

[0050] Determination of the melt index MI of the polymer: Determined in accordance with GB3682-2000;

[0051] Determination of the density of the polymer: Determined in accordance with ASTM-1050;

[0052] Determination of the bulk density of the polymer: Determined in accordance with ASTM-D1895;

[0053] Determination of the comonomer content in the polymer: Determined by 13 13C NMR.

[0054] Determination method of isotacticity: Determined by the heptane extraction method. Take 2 g of dry polypropylene sample, place it in a Soxhlet extractor and extract it with boiling heptane for 6 hours. Then dry the residue to a constant weight. The ratio of the weight (g) of the obtained polymer to 2 g is the isotacticity.

[0055] Example 1

[0056] In this example, a composite support type olefin polymerization catalyst was prepared. The specific process is as follows:

[0057] (1) Under the protection of high-purity nitrogen, 180 mL of n-heptane, 3.0 g of anhydrous magnesium chloride, 11.5 mL of n-butanol, and 1.0 mL of titanium trichloride isopropoxide were successively added to a 1 L reactor equipped with a mechanical stirrer. The temperature was raised to 85 °C and reacted for 3 h to obtain a homogeneous solution A;

[0058] (2) At 85 °C, 0.05 moL of isobutyltriethoxysilane, 0.1 moL of diisobutyl phthalate, and 0.05 moL of dimethyl 2,3-diisobutylsuccinate were added to reactant A, and the reaction was carried out at this temperature for 1.0 h to obtain reactant B;

[0059] (3) The above reactant B solution was cooled to 60 °C, and 15 g of heat-activated Grace Davison 2408 type SiO2 was added to reactant B, and the reaction was carried out for 5 h to obtain reactant C;

[0060] (4) At 60 °C, reactant C was washed 5 times with n-hexane to obtain reactant D, and finally dried with high-purity nitrogen at 80 °C to obtain a white solid powder MgCl2 / SiO2 composite support;

[0061] (5) The above reactant D was added to 100 mL of n-heptane, and then 5 mL of titanium tetrachloride solution was slowly added dropwise at 25 °C, and the reaction was carried out at this temperature for 0.5 h, and then slowly heated to 90 °C, and the reaction was carried out at this temperature for 2 h. The upper layer liquid was removed by suction filtration to obtain reactant E;

[0062] (6) 100 mL of n-heptane and 3 mL of titanium tetrachloride solution were re-added to the above reactant E, and the reaction was carried out at 90 °C for 1 h. The upper layer liquid was removed by suction filtration to obtain reactant F;

[0063] (7) At 60 °C, reactant F was washed 5 times with n-hexane, and finally dried with high-purity nitrogen at 80 °C to obtain a solid powder - composite support type olefin polymerization catalyst. The mass percentage content of each component in the catalyst is Ti = 3.52%, SPAN = 1.24.

[0064] Polymerization characterization:

[0065] Evaluation of ethylene slurry polymerization: In a 2L stainless steel reactor, after purging with nitrogen, 1.0L of n-hexane pre-dehydrated by molecular sieve, 10mL of hexene, 0.25mmol of triethylaluminum and 0.005mmol (calculated by titanium atoms) of the solid catalyst prepared above were added in sequence. Then, after heating the temperature of the system to 70°C, hydrogen was introduced until the reactor pressure reached 0.28MPa (gauge pressure), and then ethylene was continuously introduced to keep the reactor pressure at 1.0MPa (gauge pressure) during the polymer reaction time. After polymerizing for 2 hours at 80°C and 1.0MPa, the temperature was lowered and the product was discharged. The polymerization results are shown in Table 2.

[0066] SEM image of the composite support type olefin polymerization catalyst in Example 1 is as Figure 1 shown.

[0067] Example 2

[0068] In this example, a composite support type olefin polymerization catalyst was prepared. The specific process is as follows:

[0069] (1) Under the protection of high-purity nitrogen, 180mL of n-heptane, 3.0g of anhydrous magnesium chloride, 11.5mL of n-butanol and 1.0mL of titanium triisopropoxide chloride were added in sequence to a 1L reactor equipped with a mechanical stirrer. The temperature was raised to 85°C and reacted for 3h to obtain a homogeneous solution A;

[0070] (2) At 85°C, 0.05moL of 2,2-diisopropyl-1,3-dimethoxypropane, 0.1moL of dicyclohexyl phthalate and 0.1moL of diethyl 2,3-diisobutylsuccinate were added to the reactant A, and the reaction was carried out at this temperature for 1.0h to obtain a reactant B;

[0071] (3) The above reactant B solution was cooled to 60°C, and 9g of heat-activated Grace Davison 2408 type SiO2 was added to the reactant B and reacted for 5h to obtain a reactant C;

[0072] (4) At 60°C, the reactant C was washed 5 times with n-hexane to obtain a reactant D, and finally dried with high-purity nitrogen at 80°C to obtain a white solid powder MgCl2 / SiO2 composite support;

[0073] (5) The above reactant D was added to 100mL of n-heptane, and then 5mL of titanium tetrachloride solution was slowly added dropwise at 25°C and reacted at this temperature for 0.5h, and then slowly heated to 90°C and reacted at this temperature for 2h. The upper layer liquid was removed by suction filtration to obtain a reactant E;

[0074] (6) 100mL of n-heptane and 5mL of titanium tetrachloride solution were re-added to the above reactant E and reacted at 90°C for 1h. The upper layer liquid was removed by suction filtration to obtain a reactant F;

[0075] (7) At 60 °C, wash the reactant F with n - hexane 5 times, and finally dry it with high - purity nitrogen at 80 °C to obtain a solid powder - a composite support - type olefin polymerization catalyst. The mass percentage content of each component in the catalyst is Ti = 2.53%, and SPAN = 1.19.

[0076] Polymerization characterization:

[0077] Bulk polymerization evaluation of propylene: Replace a 2L stainless - steel reactor with high - purity nitrogen 3 times, add 500g of liquid propylene, then add 0.05MPa of hydrogen, and then press in a quantitative amount of 0.1 mmol of dicyclopentyl dimethoxysilane, 1.5 mmol of triethylaluminum, and 0.005 mmol (calculated by titanium atoms) of the solid catalyst prepared above. Heat up to 70 °C and react for 2h; after the polymerization is completed, release the pressure, and press out the product with nitrogen, dry it to a constant weight, weigh it, and calculate the activity; among them, the material ratio is in terms of molar ratio, alkylaluminum cocatalyst: external electron donor: catalyst = 300:20:1. The polymerization results are shown in Table 3.

[0078] Example 3

[0079] In this example, a composite support - type olefin polymerization catalyst was prepared. The specific process is as follows:

[0080] (1) Under the protection of high - purity nitrogen, successively add 180 mL of n - heptane, 3.0 g of anhydrous magnesium chloride, 11.5 mL of n - butanol, and 0.5 mL of titanium trichloride triisopropoxide to a 1L reactor equipped with a mechanical stirrer, heat up to 85 °C and react for 3h to obtain a homogeneous solution A;

[0081] (2) At 85 °C, add 0.01 mol of isobutyltriethoxysilane, 0.15 mol of diisobutyl phthalate, and 0.15 mol of dimethyl 2,3 - diisobutylsuccinate to the reactant A, and react at this temperature for 1.0h to obtain a reactant B;

[0082] (3) Cool the above reactant B solution to 60 °C, add 30 g of heat - activated Grace Davison 2408 - type SiO2 to the reactant B, and react for 5h to obtain a reactant C;

[0083] (4) At 60 °C, wash the reactant C with n - hexane 5 times to obtain a reactant D, and finally dry it with high - purity nitrogen at 80 °C to obtain a white solid powder MgCl2 / SiO2 composite support;

[0084] (5) Add the above reactant D into 100 mL of n-heptane, then slowly dropwise add 4 mL of titanium tetrachloride solution at 25 °C, and react at this temperature for 0.5 h. Then slowly raise the temperature to 90 °C and react at this temperature for 2 h. Filter off the upper layer liquid to obtain reactant E;

[0085] (6) Re-add 100 mL of n-heptane and 4 mL of titanium tetrachloride solution into the above reactant E, and react at 90 °C for 1 h. Filter off the upper layer liquid to obtain reactant F;

[0086] (7) Wash reactant F 5 times with n-hexane at 60 °C, and finally dry it with high-purity nitrogen at 80 °C to obtain a solid powder - a composite support type olefin polymerization catalyst. The mass percentage content of each component in the catalyst is Ti = 3.52%, and SPAN = 1.05.

[0087] Polymerization characterization:

[0088] Ethylene slurry polymerization evaluation: In a 2 L stainless steel reactor, after purging with nitrogen, sequentially add 1.0 L of n-hexane pre-dehydrated by molecular sieve, 10 mL of hexene, 0.25 mmol of triethylaluminum, and 0.005 mmol (calculated by titanium atoms) of the above-prepared solid catalyst. Then raise the temperature of the system to 70 °C, introduce hydrogen until the reactor pressure reaches 0.28 MPa (gauge pressure), and then continuously introduce ethylene to keep the reactor pressure at 1.0 MPa (gauge pressure) during the polymer reaction time. After polymerizing at 80 °C and 1.0 MPa for 2 h, cool down and discharge the product. The polymerization results are shown in Table 2.

[0089] The catalyst preparation methods and polymerization characterization methods of Examples 4 - 8 are the same as those of Example 1. The substances added and the addition amounts in the specific preparation are shown in Table 1, and the polymerization results are shown in Table 2.

[0090] The catalyst preparation methods and polymerization characterization methods of Examples 9 - 12 are the same as those of Example 2. The substances added and the addition amounts in the specific preparation are shown in Table 1, and the polymerization results are shown in Table 3.

[0091] The catalyst preparation method and polymerization characterization method of Example 13 are the same as those of Example 1, except that titanium triisopropoxide chloride is replaced with titanium diisopropoxide dichloride. The mass percentage content of each component in the catalyst is Ti = 3.21%, and SPAN = 1.22. The polymerization results are shown in Table 2.

[0092] The catalyst preparation method and polymerization characterization method of Example 14 are the same as those of Example 2, except that titanium triisopropoxide chloride is replaced with titanium tetrahydrofuran chloride. The mass percentage content of each component in the catalyst is Ti = 2.5%, and SPAN = 1.7. The polymerization results are shown in Table 3.

[0093] Table 1 Substances added, dosages in catalyst preparation, and component contents in the catalyst

[0094]

[0095]

[0096] Comparative Example 1

[0097] A catalyst was prepared in this comparative example. The specific process was as follows:

[0098] (1) Under the protection of high-purity nitrogen, 180 mL of n-heptane, 3.0 g of anhydrous magnesium chloride and 11.5 mL of n-butanol were successively added to a 1 L reactor equipped with a mechanical stirrer, and the temperature was raised to 85 °C and reacted for 3 h to obtain a homogeneous solution A;

[0099] (2) At 85 °C, 0.2 moL of methyltriacetoxysilane was added to reactant A, and the reaction was carried out at this temperature for 1.0 h to obtain reactant B;

[0100] (3) The temperature of the above reactant B solution was lowered to 60 °C, and 15 g of heat-activated 955-type SiO2 was added to reactant B, and the reaction was carried out for 5 h to obtain reactant C;

[0101] (4) At 60 °C, reactant C was washed 5 times with n-hexane to obtain reactant D, and finally dried with high-purity nitrogen at 80 °C to obtain a white solid powder MgCl2 / SiO2 composite support;

[0102] (5) The above reactant D was added to 100 mL of n-heptane, and then 8 mL of titanium tetrachloride solution was slowly added dropwise at 25 °C, and the reaction was carried out at this temperature for 0.5 h, and then slowly heated to 90 °C, and the reaction was carried out at this temperature for 2 h, and the upper layer liquid was removed by suction filtration to obtain reactant E;

[0103] (6) 100 mL of n-heptane and 5 mL of titanium tetrachloride solution were re-added to the above reactant E, and the reaction was carried out at 90 °C for 1 h, and the upper layer liquid was removed by suction filtration to obtain reactant F;

[0104] (7) At 60 °C, reactant F was washed 5 times with n-hexane, and finally dried with high-purity nitrogen at 80 °C to obtain a solid powder - polyethylene catalyst. The mass percentage content of each component in the catalyst was Ti = 3.25%, and SPAN = 1.45.

[0105] Polymerization characterization:

[0106] Evaluation of ethylene slurry polymerization: In a 2 L stainless steel reactor, after purging with nitrogen, 1.0 L of n-hexane pre-dehydrated by molecular sieve, 10 mL of hexene, 0.25 mmol of triethylaluminum, and 0.005 mmol (calculated by titanium atoms) of the solid catalyst prepared above were added in sequence. Then, after heating the temperature of the system to 70 °C, hydrogen was introduced until the reactor pressure reached 0.28 MPa (gauge pressure), and then ethylene was continuously introduced to keep the reactor pressure at 1.0 MPa (gauge pressure) during the polymer reaction time. After polymerizing for 2 h at 80 °C and 1.0 MPa, the temperature was decreased and the product was discharged. The results of slurry polymerization are shown in Table 2.

[0107] Comparative Example 2

[0108] In this comparative example, a catalyst was prepared. The specific process was as follows:

[0109] (1) Under the protection of high-purity nitrogen, 180 mL of n-heptane, 3.0 g of anhydrous magnesium chloride, and 11.5 mL of n-butanol were added in sequence to a 1 L reactor equipped with a mechanical stirrer. The temperature was raised to 85 °C and reacted for 3 h to obtain a homogeneous solution A.

[0110] (2) At 85 °C, 0.2 moL of methyltriacetoxysilane was added to reactant A and reacted at this temperature for 1.0 h to obtain reactant B.

[0111] (3) The solution of the above reactant B was cooled to 60 °C, and 15 g of heat-activated 2408 type SiO2 was added to reactant B and reacted for 5 h to obtain reactant C.

[0112] (4) At 60 °C, reactant C was washed with n-hexane 5 times to obtain reactant D, and finally dried with high-purity nitrogen at 80 °C to obtain a white solid powder MgCl2 / SiO2 composite support.

[0113] (5) The above reactant D was added to 100 mL of n-heptane, and then 8 mL of titanium tetrachloride solution was slowly added dropwise at 25 °C and reacted at this temperature for 0.5 h, and then slowly heated to 90 °C and reacted at this temperature for 2 h. The upper layer liquid was removed by suction filtration to obtain reactant E.

[0114] (6) 100 mL of n-heptane and 5 mL of titanium tetrachloride solution were re-added to the above reactant E and reacted at 90 °C for 1 h. The upper layer liquid was removed by suction filtration to obtain reactant F.

[0115] (7) At 60 °C, reactant F was washed with n-hexane 5 times, and finally dried with high-purity nitrogen at 80 °C to obtain a solid powder - polyethylene catalyst. The mass percentage content of each component in the catalyst was Ti = 3.57%, SPAN = 1.50.

[0116] Polymerization characterization:

[0117] Evaluation of ethylene slurry polymerization: In a 2 L stainless steel reactor, after purging with nitrogen, 1.0 L of n - hexane pre - dehydrated by molecular sieve, 10 mL of hexene, 0.25 mmol of triethylaluminum, and 0.005 mmol (calculated by titanium atoms) of the solid catalyst prepared above were added in sequence. Then, after heating the temperature of the system to 70 °C, hydrogen was introduced until the reactor pressure reached 0.28 MPa (gauge pressure), and then ethylene was continuously introduced to keep the reactor pressure at 1.0 MPa (gauge pressure) during the polymerization reaction time. After polymerization at 80 °C and 1.0 MPa for 2 h, the temperature was decreased and the product was discharged. The results of slurry polymerization are shown in Table 2.

[0118] Comparative Example 3

[0119] In this example, a composite - support - type olefin polymerization catalyst was prepared. The specific process is as follows:

[0120] (1) Under the protection of high - purity nitrogen, 180 mL of n - heptane, 3.0 g of anhydrous magnesium chloride, 11.5 mL of n - butanol, and 1.0 mL of tetrabutyl titanate were added in sequence to a 1 L reactor equipped with a mechanical stirrer. The temperature was raised to 85 °C and reacted for 3 h to obtain a homogeneous solution A;

[0121] (2) At 85 °C, 0.15 moL of 2,2 - diisopropyl - 1,3 - dimethoxypropane and 0.1 moL of diethyl 2,3 - diisobutylsuccinate were added to reactant A, and the reaction was carried out at this temperature for 1.0 h to obtain reactant B;

[0122] (3) The temperature of the above - mentioned reactant B solution was decreased to 60 °C, and 9 g of heat - activated Grace Davison 2408 - type SiO2 was added to reactant B, and the reaction was carried out for 5 h to obtain reactant C;

[0123] (4) At 60 °C, reactant C was washed 5 times with n - hexane to obtain reactant D, and finally dried with high - purity nitrogen at 80 °C to obtain a white solid powder MgCl2 / SiO2 composite support;

[0124] (5) The above - mentioned reactant D was added to 100 mL of n - heptane, and then 5 mL of titanium tetrachloride solution was slowly added dropwise at 25 °C, and the reaction was carried out at this temperature for 0.5 h, and then slowly heated to 90 °C. The reaction was carried out at this temperature for 2 h, and the upper - layer liquid was removed by suction filtration to obtain reactant E;

[0125] (6) 100 mL of n - heptane and 5 mL of titanium tetrachloride solution were re - added to the above - mentioned reactant E, and the reaction was carried out at 90 °C for 1 h, and the upper - layer liquid was removed by suction filtration to obtain reactant F;

[0126] (7) At 60 °C, wash the reactant F with n-hexane 5 times, and finally dry it with high-purity nitrogen at 80 °C to obtain a solid powder - a composite support type olefin polymerization catalyst. The mass percentage content of each component in the catalyst is Ti = 2.51%, and SPAN = 1.21.

[0127] Polymerization characterization:

[0128] Bulk polymerization evaluation of propylene: Replace a 2L stainless steel reactor with high-purity nitrogen 3 times, add 500g of liquid propylene, then add 0.05MPa of hydrogen, and then press in a quantitative amount of 0.1 mmol of dicyclopentyl dimethoxysilane, 1.5 mmol of triethylaluminum, and 0.005 mmol (calculated based on titanium atoms) of the solid catalyst prepared above. Heat up to 70 °C and react for 2h; after the polymerization is completed, relieve the pressure, and press out the product with nitrogen, dry it to a constant weight, and weigh and calculate the activity; among them, the material ratio is calculated by molar ratio, alkyl aluminum cocatalyst: external electron donor: catalyst = 300:20:1, and the polymerization results are shown in Table 3.

[0129] The catalyst preparation method and polymerization characterization method of Comparative Example 4 are the same as those of Example 2, except that titanium triisopropoxide chloride is not added. The mass percentage content of each component in the catalyst is Ti = 2.50%, and SPAN = 1.17. The polymerization results are shown in Table 3.

[0130] The catalyst preparation method and polymerization characterization method of Comparative Example 5 are the same as those of Example 2, except that titanium triisopropoxide chloride is not added. The mass percentage content of each component in the catalyst is Ti = 2.42%, and SPAN = 1.21. The polymerization results are shown in Table 3.

[0131] Table 2 Ethylene slurry polymerization results of different catalysts

[0132]

[0133] Table 3 Bulk polymerization results of different catalysts for propylene

[0134]

[0135] In summary, the present invention uses a two-step method to prepare a composite support type olefin polymerization catalyst by first preparing a composite support and then loading titanium. (1) During the preparation of the catalyst, the temperature is raised above room temperature when loading titanium, and low-temperature treatment is not required; (2) The catalyst prepared by the two-step method has a more uniform and regular morphology, thus ensuring that the polymerization product has a better particle morphology, greatly reducing the content of fines in production operation, and further ensuring the long-term stable operation of the device; (3) During the preparation of the catalyst, the amount of titanium tetrachloride is further reduced by adding alkoxy titanium chloride compounds, which also helps to improve the hydrogen response sensitivity of the catalyst and effectively reduces the pollution to the environment caused by titanium tetrachloride; (4) During the preparation of the catalyst, by adding three or more different types of electron donor compounds, the catalyst has high activity, high copolymerization ability and high hydrogen response sensitivity when catalyzing olefin polymerization.

[0136] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent substitution methods and are all included in the protection scope of the present invention.

Claims

1. A composite support type olefin polymerization catalyst, characterized in that: It includes a MgCl₂-porous silica composite support, a titanium-containing transition metal active ingredient supported on the composite support, and an electron donor compound modifier; the electron donor compound includes at least three of silane compounds, phthalate compounds, diether compounds, spiro-substituted succinate compounds, and other succinate compounds; The preparation method of the composite support type olefin polymerization catalyst includes the following steps: S1: Under an inert atmosphere, after reacting an alkane solvent, anhydrous magnesium chloride, an organic alcohol, and an alkoxytitanium chloride compound, an electron donor compound is added and the reaction is continued to obtain a first reactant; S2: Silica gel is added to the first reactant to react to obtain a second reactant; S3: An alkane is added to the second reactant, and a titanium tetrachloride solution is added dropwise at least twice to react. After filtering off the upper layer liquid, n-heptane and a titanium tetrachloride solution are added dropwise to react to obtain the composite support type olefin polymerization catalyst; The molar ratio of the alkoxytitanium chloride compound to the anhydrous magnesium chloride is (0.05 - 0.1):

1.

2. The composite support type olefin polymerization catalyst according to claim 1, wherein: The content of the electron donor compound in the composite support type olefin polymerization catalyst is 0.10 wt% - 10.00 wt%.

3. The composite carrier type olefin polymerization catalyst according to claim 1, characterized in that: The Ti content in the composite support type olefin polymerization catalyst is 1.00 wt% - 5.00 wt%.

4. The composite carrier type olefin polymerization catalyst according to claim 1, characterized in that: In the MgCl₂-porous silica composite support, the mass ratio of MgCl₂ to porous silica is 1:(3 - 10).

5. A method for preparing a composite support type olefin polymerization catalyst according to any one of claims 1 to 4, characterized in that: It includes the following steps: S1: Under an inert atmosphere, after reacting an alkane solvent, anhydrous magnesium chloride, an organic alcohol, and an alkoxytitanium chloride compound, an electron donor compound is added and the reaction is continued to obtain a first reactant; S2: Silica gel is added to the first reactant to react to obtain a second reactant; S3: An alkane is added to the second reactant, and a titanium tetrachloride solution is added dropwise at least twice to react. After filtering off the upper layer liquid, n-heptane and a titanium tetrachloride solution are added dropwise to react to obtain the composite support type olefin polymerization catalyst; The molar ratio of the alkoxytitanium chloride compound to the anhydrous magnesium chloride is (0.05 - 0.1):

1.

6. The preparation method of the composite support type olefin polymerization catalyst according to claim 5, wherein: The reaction temperature of S2 is 30°C - 70°C, and the reaction time is 2 h - 5 h.

7. The preparation method of the composite support type olefin polymerization catalyst according to claim 5, characterized in that: In S3, when the titanium tetrachloride solution is added dropwise for the first time, the reaction is carried out at 10°C - 35°C for 0.1 h - 2.0 h, and then the temperature is raised to 60°C - 95°C for 1.0 h - 3.0 h.

8. The preparation method of the composite support type olefin polymerization catalyst according to claim 5, characterized in that: In S3, when the titanium tetrachloride solution is added dropwise for the second time, the reaction is carried out at 80°C - 90°C for 1.0 h - 5.0 h.

9. Use of a composite support type olefin polymerization catalyst according to any one of claims 1 - 4 in the preparation of polyolefins.

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