Catalyst for olefin polymerization

Abstract

The invention relates to a catalyst for olefin polymerization, which specifically comprises the following components in percentage by weight: (a) a catalytic component containing 10-25% of magnesium, 1-10% of titanium, 40-60% of halogen and 1-30% of at least one heteroatom-containing ortho-ester selected from a general formula (I); (b) an aluminum alkyl compound; (c) optionally, an external electron donor; as a compound with a special electronic structure is adopted as an internal electron donor, the synthesized Ziegler-Natta catalyst shows very high catalytic activity in propylene (co) polymerization, and the obtained polymer has high stereospecificity. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the field of preparation of supported Ziegler-Natta catalysts, and specifically relates to an olefin polymerization catalytic component and a catalyst thereof, and particularly relates to a catalytic component and a catalyst thereof for propylene (co)polymerization. Background Art

[0002] Supported Ziegler-Natta catalyst is a solid titanium catalyst with magnesium, titanium, halogen and electron donor as basic components. It is particularly suitable for the polymerization of α-olefins with 3 or more carbon atoms. The obtained olefin polymer has a high yield and stereoregularity. Among them, the electron donor is one of the essential components of the supported Ziegler-Natta catalyst, which can effectively improve the activity and isotacticity of the catalyst. Studies have shown that polyolefin catalysts are constantly updated with the development of electron donor compounds.

[0003] At present, dibasic aromatic carboxylic acid ester compounds are more commonly used in industry as internal electron donors of Ziegler-Natta catalysts, such as di-n-butyl phthalate or diisobutyl phthalate (PM Trivedi, et al. J. Polym. Res., 2021, 28, Article number: 45). However, since phthalates are plasticizers, long-term use will bring potential risks to human health. Therefore, various internal electron donors have been developed to replace phthalate internal electron donors, such as 1,3-diethers, glycol lipids and succinate compounds. Among them, the supported Ziegler-Natta catalyst with 1,3-diether compounds as electron donors is a recognized new generation of electron donor compounds with high activity and isotacticity, such as 9,9-di(methoxymethyl)fluorene recently disclosed by CN1090194C, CN00103538 and CN1137155C. In addition, the 1,8-naphthalene diphenol esters (WO2011084691A2 and US20110213106A1) reported by Chang et al. of BASF and the 1,2-benzenediphenol esters (US20190338054A1 and CN102325808A) structures disclosed by Dow have high activity and isotacticity of catalysts loaded with electron donors. However, these compounds are difficult to synthesize and have high costs, and no industrial reports have been seen so far.

[0004] Introducing heteroatoms into the aromatic ring structure of phthalic acid esters can effectively change the coordination mode and strength of the carbonyl group and the carrier MgCl2, thereby changing the insertion rate during propylene polymerization and improving the activity and isotacticity of the catalyst. For example, patents CN101824108A, CN102268110A and CN101423566A reported that the aromatic ring structure of phthalic acid was changed to a furan ring structure, and the presence of heteroatoms can effectively change the electronic structure of the diester. Summary of the invention

[0005] The present invention provides a catalyst component for the polymerization of CH2=CHR olefins, wherein R is hydrogen or a hydrocarbon group having 1 to 12 carbon atoms. Another object of the present invention is to provide a catalyst containing the above catalyst component.

[0006] Specifically, in terms of weight percentage, it comprises 10% to 25% magnesium, 1% to 10% titanium, 40% to 60% halogen and 1% to 30% internal electron donor, characterized in that the internal electron donor compound is selected from at least one heteroatom-containing phthalic acid ester in the general formula (I):

[0007]

[0008] Wherein, the group X is a heteroatom such as oxygen, sulfur or nitrogen, and the groups R1 and R2 are the same or different from each other and are C1 to C 20 A linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl radical, optionally containing heteroatoms.

[0009] Furthermore, in the above technical solution, in the above compound general formula (I), X is preferably a nitrogen atom.

[0010] Furthermore, in the above technical solution, in the above compound general formula (I), R1 and R2 are preferably C1 to C 10 An alkyl group, a cycloalkyl group or an arylalkyl group, more preferably a C1-C 10 The alkyl group is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a neopentyl group, and particularly preferably an ethyl group, an isopropyl group, an n-butyl group or an isobutyl group.

[0011] Furthermore, in the above technical scheme, the above compound general formula (I) includes but is not limited to: dimethyl 3,4-pyridinedicarboxylate, diethyl 2,3-pyridinedicarboxylate, di-n-butyl 4,5-pyridazinedicarboxylate, diisopropyl 3,4-pyridazinedicarboxylate, diisobutyl 2,3-pyrazinedicarboxylate, dineopentanol 4,5-pyrimidinedicarboxylate, and diphenol 1,2,4-triazine-5,6-dicarboxylate.

[0012] Further, in the above technical solution, the general formula (I) of the above compound can be obtained by an esterification reaction of the corresponding acid (anhydride), as shown in the following reaction formula, which is simple and feasible. In the following synthetic route, the substituents R1, R2, and X in the structural formula are defined the same as R1, R2, and X in formula (I).

[0013]

[0014] Further, in the above technical solution, the particle size distribution of magnesium in the catalytic component is 20-250 μm, and is provided by a magnesium halide alcoholate with the general formula Mg(OR')mM (2-m) ·nROH, where R' is an alkyl group, arylalkyl group or aryl group with 1- 20 carbon atoms; M is a halogen; m is an integer of 0≤m≤2; n is a decimal or integer of 0<n<6; R is an alkyl group or arylalkyl group with 1- 20 carbon atoms.

[0015] Mg(OR′)mM(2-m)+nROH→Mg(OR′) m M (2-m) ·nROH

[0016] Further, in the above technical solution, the magnesium halide in the magnesium halide alcoholate is selected from one of magnesium dichloride, magnesium dibromide, methoxymagnesium chloride or ethoxymagnesium chloride; the alcohol in the magnesium halide alcoholate is selected from one of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol, and ethanol is preferred.

[0017] Further, in the above technical solution, the magnesium halide alcoholate is synthesized according to the literature report (US4399054). Taking the synthesis of the ethanolate of magnesium chloride as an example, the specific synthesis method is as follows: At room temperature, 24 g of anhydrous MgCl2, 390 mL of vaseline oil, 50 mL of anhydrous ethanol, 10 mL of silicone oil and 2 mL of span are added to a high-pressure reaction kettle, and stirred and heated to 130 °C under nitrogen protection for 3 hours to completely dissolve the solid. Then, nitrogen is continuously filled into the kettle and maintained at a pressure of 1 MPa, and the discharge valve is opened to allow the mixture in the kettle to pass through a thin tube with a diameter of 1.2 mm and a length of 3.54 m, and washed 5 times with hexane, and dried at room temperature to obtain a spherical carrier of the ethanolate of MgCl2.

[0018] Further, in the above technical solution, titanium in the catalytic component is provided by a compound with the general formula TiA n (OR) 4-n , where R is a hydrocarbon group with 1-20 carbon atoms; A is a halogen; n = 1-4. Specific compounds such as titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tetrabutoxytitanium, tetraethoxytitanium, trichloroethoxytitanium, dichlorodiethoxytitanium or trichloroethoxytitanium are provided, and titanium tetrachloride is preferred.

[0019] The present invention provides a preparation method of a catalytic component a, comprising: (1) adding a spherical magnesium halide alcoholate to a titanium compound at -40 to 10°C, reacting for 1 to 4 hours, wherein the molar ratio of magnesium to titanium is 1:5 to 1:50; (2) heating the temperature to 30 to 80°C, adding an inner electron compound, wherein the molar ratio of magnesium to the inner electron donor compound is 2:1 to 15:1; (3) heating the temperature to 100 to 150°C, reacting for 1 to 4 hours; (4) filtering, then adding the same amount of titanium compound as in step (1), reacting at 110 to 130°C for 1 to 4 hours, and filtering, washing, and drying to obtain the catalyst.

[0020] The above catalytic components are the main components, and the present invention can further provide a catalyst for olefin polymerization. Specifically comprising:

[0021] (a) a catalyst component a containing magnesium, titanium, halogen and at least one heteroatom-containing phthalic acid ester selected from the general formula (I);

[0022] (b) an alkylaluminum compound;

[0023] (c) optionally, an external electron donor component;

[0024] The usage of each component is 1:5-1000:0-500 based on the molar ratio of titanium:aluminum:external electron donor compound.

[0025] Furthermore, in the above technical solution, the alkylaluminum compound is a trialkylaluminum compound, such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, a mixture of trialkylaluminum and alkylaluminum halide or alkylaluminum hydride, or an alkylaluminumoxane.

[0026] Furthermore, in the above technical solution, the external electron donor can be selectively added as needed. For olefin polymers that need to have very high stereoregularity (such as an isotactic index greater than 99%), it is recommended to add an external electron donor compound.

[0027] The external electron donor may be a 1,3-diether compound of the general formula (II).

[0028]

[0029] Among them, R3-R 10 may be the same or different and are hydrogen or a hydrocarbon group having 1 to 18 carbon atoms, and R3-R 10 One or more of the groups may be linked to form a ring. 10 is a C1-C4 alkyl group, R5 and R6 form an unsaturated condensed ring, and R3, R4, R7 and R8 are all hydrogen. Particularly preferably, the external electron donor is 9,9-bis(methoxymethyl)fluorene.

[0030] Furthermore, in the above technical solution, the usage ratio of each component in the catalyst is preferably 1:25-100-25-300, calculated on the molar ratio of titanium:aluminum:external electron donor compound.

[0031] The catalyst of the present invention can be used for olefin polymerization, especially homopolymerization of propylene or copolymerization of propylene with other olefins to obtain polymers with very high isotactic index. At the same time, it is not excluded that the catalyst is suitable for the production of polyethylene and copolymerization of ethylene with α-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene or 1-octene.

[0032] When used for propylene polymerization, various methods in the prior art can be used, which can be carried out in liquid phase or gas phase, or in a combination of liquid phase and gas phase polymerization stages. The polymerization is usually carried out at 0 to 150°C, preferably 40 to 90°C. The polymerization pressure is 0.01 to 10 MPa. Hydrogen or other compounds that can act as chain transfer agents can be used to control the molecular weight of the polymer.

[0033] Since the present invention adopts an vicinal diester compound containing a nitrogen atom heterocyclic structure as an internal electron donor, its unique electronic effect makes the catalyst have excellent comprehensive performance. When used for propylene (co)polymerization, a satisfactory polymerization yield can be obtained, and the stereospecificity of the polymer is high. DETAILED DESCRIPTION

[0034] The following embodiments are used to further illustrate the present invention, but not to limit the present invention.

[0035] 1. Synthesis of nitrogen-containing heterocyclic phthalic acid ester compounds

[0036] The nitrogen-containing heterocyclic phthalic acid ester compound can be obtained by esterifying the nitrogen-containing heterocyclic phthalic acid (anhydride) with the corresponding alcohol. Diisobutyl phthalate (99%) was purchased from TCI (Shanghai).

[0037] Example 1

[0038] Synthesis of 2,3-pyrazine-dicarboxylic acid diisobutyl ester. Add 33.6g 2,3-pyrazine-dicarboxylic acid and 70mL isobutyl alcohol into a 150mL flask and stir and reflux overnight. Column chromatography separation was performed to obtain 55.9g of colorless and transparent liquid product pyrazine-2,3-dicarboxylic acid diisobutyl ester with a yield of 99%. 1 H NMR see Table 1.

[0039] Example 2

[0040] Synthesis of dimethyl 3,4-pyridinedicarboxylate. The synthesis method is the same as in Example 1, except that 33.4 g of 3,4-pyridinedicarboxylic acid and 28 mL of methanol are used to replace 33.6 g of 2,3-pyrazine-dicarboxylic acid and 70 mL of isobutanol. The yield is 99%. 1 H NMR see Table 1.

[0041] Example 3

[0042] Synthesis of diethyl 2,3-pyridinedicarboxylate. The synthesis method is the same as in Example 1, except that 33.4 g of 2,3-pyridinedicarboxylic acid and 40.0 mL of ethanol are used to replace 33.6 g of 2,3-pyrazine-dicarboxylic acid and 70 mL of isobutanol. The yield is 99%. 1 H NMR see Table 1.

[0043] Example 4

[0044] Synthesis of di-n-butyl 4,5-pyridazinedicarboxylate. The synthesis method is the same as in Example 1, except that 33.6 g of 4,5-pyridazinedicarboxylic acid and 70 mL of n-butanol are used instead of 33.6 g of 2,3-pyrazinedicarboxylic acid and 70 mL of isobutanol. The yield is 99%. 1 H NMR see Table 1.

[0045] Example 5

[0046] Synthesis of diisopropyl 3,4-pyridazinedicarboxylate. The synthesis method is the same as in Example 1, except that 33.6 g 3,4-pyridazinedicarboxylic acid and 53.5 mL isopropanol are used instead of 33.6 g 2,3-pyrazinedicarboxylic acid and 70 mL isobutanol. The yield is 99%. 1 H NMR see Table 1.

[0047] Example 6

[0048] Synthesis of 4,5-pyrimidinedicarboxylic acid dineopentyl alcohol ester. The synthesis method is the same as in Example 1, except that 33.6 g of 4,5-pyrimidinedicarboxylic acid and 61.7 mg of neopentyl alcohol are used to replace 33.6 g of 2,3-pyrazine-dicarboxylic acid and 70 mL of isobutanol, with a yield of 99%. 1 HNMR see Table 1.

[0049] Example 7

[0050] Synthesis of 1,2,4-triazine-5,6-dicarboxylic acid diphenol ester. The synthesis method is the same as that of Example 1, except that 33.8 g of 1,2,4-triazine-5,6-dicarboxylic acid and 65.8 g of phenol are used to replace 33.6 g of 2,3-pyrazine-dicarboxylic acid and 70 mL of isobutyl alcohol, with a yield of 75%. 1 HNMR see Table 1.

[0051] Table 1. Internal electron donors1 HNMR results

[0052]

[0053] 2. Preparation of Catalytic Component A

[0054] TiCl4 was added to a dry glass reactor protected by nitrogen and cooled to -20°C. Microspherical magnesium chloride alcoholate (magnesium alcohol ratio of 2.9:1) carrier was added under stirring. The mixing ratio of carrier and TiCl4 was 1g:20mL. The reaction mixture was heated uniformly from -20°C to 0°C, and then to 70°C. The internal electron donor was added to the reactor, and the reaction mixture was heated to 110°C and continued to react for 2h; filtered, fresh equal amount of TiCl4 was added again, heated to 120°C and continued to react for 2h, filtered, washed the filter cake with hexane, and vacuum dried to obtain the catalyst component. The loading amount of the internal electron donor was determined by Angent 8890A gas chromatograph; the titanium loading amount was determined according to the spectrophotometer.

[0055] 3. Propylene polymerization

[0056] 0.2 mL of an external electron donor dicyclopentyldimethoxysilane, 8.0 mL of a hexane solution of a co-catalyst triethylaluminum with a concentration of 1 mol / L, and 0.01 mmol (calculated as titanium) of the catalyst component a prepared by the present invention were added to a 5 L autoclave in sequence, 2.5 L of liquid propylene and 0.2 MPa of hydrogen were introduced, stirred and mixed uniformly at room temperature, heated to 70° C., stirred for reaction for 2 h, the autoclave was opened to take out the polypropylene, and the polymer was weighed after cooling to room temperature and the propylene was completely volatilized, the activity of the catalyst was calculated, and the isotacticity, bulk density, melt index, particle size distribution, molecular weight distribution and other properties of the polypropylene were measured.

[0057] In Examples 8-14, propylene polymerization was carried out using the Ziegler-Natta catalyst synthesized by the internal electron donor in Examples 1-7 and the above-mentioned polymerization steps. The polymerization results are shown in Table 2.

[0058] Table 2. Aggregation results

[0059]

[0060] From the above results, it can be seen that the activity and isotacticity of the synthesized catalyst containing heteroatom phthalate as internal electron donor are significantly better than those of the commercial diisobutyl phthalate-supported catalyst.

Claims

1. A catalyst for olefin polymerization, comprising, by weight percentage, 10% to 25% magnesium, 1% to 10% titanium, 40% to 60% halogen and 1% to 30% internal electron donor, characterized in that The internal electron donor compound is selected from at least one heteroatom-containing phthalic acid ester of the general formula (I): Wherein the group X is an oxygen, sulfur or nitrogen heteroatom, the groups R1 and R2 are the same or different from each other and are selected from C1 to C 20 A linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl radical, optionally containing heteroatoms.

2. The catalyst according to claim 1, characterized in that In the general formula (I) of the internal electron donor compound, R1 and R2 are ethyl, isopropyl, n-butyl or isobutyl.

3. The catalyst according to claim 1, characterized in that The internal electron donor compound of general formula (I) is dimethyl 3,4-pyridinedicarboxylate, diethyl 2,3-pyridinedicarboxylate, di-n-butyl 4,5-pyridazinedicarboxylate, diisopropyl 3,4-pyridazinedicarboxylate, diisobutyl 2,3-pyrazinedicarboxylate, dineopentanol 4,5-pyrimidinedicarboxylate, and diphenol 1,2,4-triazine-5,6-dicarboxylate.

4. The catalyst according to claim 1, characterized in that The particle size distribution of magnesium in the catalyst component is 20 to 250 μm, and the general formula is Mg(OR')mM (2-m) ·nROH is provided by a magnesium halide alcoholate, wherein R' is C1~C 20 alkyl, arylalkyl or aryl; M is halogen; m is an integer where 0 ≤ m ≤ 2; n is a decimal or an integer where 0 < n < 6; R is an alkyl or arylalkyl of C1-C 20 ; The titanium in the catalytic component is represented by the general formula TiA n (OR”) 4-n A compound is provided, wherein R" is a hydrocarbon group having 1 to 20 carbon atoms; A is a halogen; and n=1 to 4.

5. The catalyst according to claim 7, characterized in that A magnesium halide alcoholate of magnesium is provided, wherein the magnesium halide is one of magnesium dichloride, magnesium dibromide, chloromethoxymagnesium or chloroethoxymagnesium; and the alcohol in the magnesium halide alcoholate is one of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol; The titanium in the catalytic component is provided by titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxide, titanium tetraethoxide, titanium triethoxide monochloride, titanium diethoxide dichloride or titanium triethoxide monochloride.

6. A catalyst characterized in that Catalysts include: (a) the catalyst according to any one of claims 1 to 5; (b) an alkylaluminum compound; (c) optionally, an external electron donor component; The usage of each component is 1:5-1000:0-500 based on the molar ratio of titanium:aluminum:external electron donor compound.

7. The catalyst according to claim 6, characterized in that The alkylaluminum compound is a trialkylaluminum compound. The external electron donor is a 1,3-diether compound of general formula (II); Among them, R3-R 10 may be the same or different and are hydrogen or a hydrocarbon group having 1 to 18 carbon atoms, and R3-R 10 One or more of the groups may be linked to form a ring.

8. The catalyst according to claim 7, characterized in that The alkylaluminum compound is triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, a mixture of a trialkylaluminum and an alkylaluminum halide or an alkylaluminum hydride, or an alkylaluminumoxane; The compound of general formula (II) is characterized in that R9 and R 10 It is a C1-C4 alkyl group, R5 and R6 form an unsaturated condensed ring, and R3, R4, R7 and R8 are all hydrogen.

9. The catalyst according to claim 8, characterized in that The external electron donor is 9,9-bis(methoxymethyl)fluorene.

10. The catalyst according to claim 8, characterized in that Calculated by the molar ratio of titanium:aluminum:external electron donor compound, the dosage ratio of each component in the catalyst is 1:25-100:25-300.

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