Preparation method of diamine titanium-zirconium-hafnium metal catalyst based on NN bidentate coordination and application of diamine titanium-zirconium-hafnium metal catalyst in preparation of bimodal polyethylene

Abstract

The invention provides a preparation method of a diamine metal catalyst based on NN two-tooth coordination and application of the catalyst in catalyzing olefin polymerization. The diamine titanium-zirconium-hafnium metal catalyst based on NN two-tooth coordination has the advantages of simple synthesis, easily available raw materials, high product yield and high catalytic activity, and is especially suitable for one-pot synthesis of high-performance bimodal polyethylene. By changing the substituent group of the metal catalyst, the polymerization process can be conveniently controlled, so that the structure of the polymer is regulated and controlled, and different catalytic properties are realized. The novel two-tooth coordinated diamine metal catalyst disclosed by the invention shows extremely high activity in the presence of a cocatalyst (such as [Ph3C] [B (C6F5) 4] and the like), and the highest activity is 15600kg (polymer). Mol <-1 > (M). H <-1 >. Therefore, the report of the invention has original innovation, and can enhance the competitive capacity of the polyolefin high polymer material technology market in China.

Description

Technical Field

[0001] This invention relates to the synthesis of metal catalysts for olefin coordination polymerization and their application in the preparation of polyolefins. Background Technology

[0002] Polyolefins are a class of polymeric materials produced by polymerization reactions of olefin monomers, such as ethylene, propylene, and other olefins, and they occupy an extremely important position in modern society. Due to their unique structure, excellent physical and mechanical properties, chemical stability, and relatively low production costs, polyolefin materials are widely used in all aspects of industrial production and daily life, becoming an indispensable basic material. Bimodal polyethylene is a special type of polyolefin material, with its molecular weight distribution curve exhibiting a distinct bimodal distribution, corresponding to both high-molecular-weight and low-molecular-weight components. The high-molecular-weight component is typically ultra-high-molecular-weight polyethylene, providing excellent mechanical strength, impact resistance, and resistance to environmental stress cracking, and is usually used as a "reinforcing phase" in the material; while the low-molecular-weight component effectively reduces melt viscosity and improves flowability, thus acting as a processing aid. This unique structure gives it both the high mechanical properties and processing performance of traditional polyethylene materials, attracting increasing attention in the field of polyolefin materials. The key to the successful preparation of this type of polyolefin material lies in the metal catalyst, which has a significant impact on the structure and properties of polyolefin materials. For example, during polymerization, the catalyst affects the molecular weight, molecular weight distribution, and comonomer content of the polymer, thus leading to different mechanical properties of the polyolefin material. Therefore, it is essential to develop metal catalysts with excellent catalytic performance.

[0003] In the 1980s, Kaminsky's research team synthesized bimodal polyethylene using two metal catalysts (Makromol. Chem. Rapid Commun. 1988, 9, 457-461), and discovered that each catalyst in this system functions independently during polymerization, effectively controlling the microstructure of polyethylene. In 2002, Fujita's team successfully prepared unimodal, bimodal, and even trimodal polyethylene using FI catalysts by controlling the polymerization temperature (Macromolecules 2003, 36, 523-525). Subsequently, Britovsek's team synthesized bimodal polyethylene in a one-step process using a mixed catalytic system composed of bis(imine)pyridine iron and ZnEt2 (J. Am. Chem. Soc. 2004, 126, 10701-10712). Professor Li Bogeng's team prepared bimodal polyethylene using FI catalyst by introducing ZnEt2 as a chain transfer agent in polymerization (Eur. Polym. J. 2013, 49, 1823-1831). In addition, Alt's team (Organomet. Chem. 2002, 658, 259-265) and Marks' team (Chem. Rev. 2011, 111, 2450-2485) also successfully prepared bimodal or broadly distributed polyethylene using a binuclear catalyst with dual active sites. In recent years, Professor Liu Shaofeng's team has developed group IV metal complexes of phenoxyimine with active NH groups (Chem. Front. 2024, 11, 613-623), which can selectively prepare unimodal or bimodal polyethylene through different activation processes.

[0004] In this invention, a class of metal complexes with diamines as the ligand framework were designed and synthesized. A series of new ligands were synthesized via the coupling reaction of halobenzenes with diamines. The resulting ligands were then reacted in a one-pot process with in-situ synthesized MMe4 (M = Ti, Zr, or Hf) to obtain an N / N bidentate coordination diamine-based titanium-zirconium-hafnium metal catalyst, exhibiting high yield and significant economic benefits. Application of this type of metal catalyst in the synthesis of polyolefin materials revealed that by modifying the substituents in the catalyst structure, the molecular weight and α-olefin insertion rate of the resulting polymer could be effectively improved, enabling the one-pot synthesis of high-performance bimodal polyethylene. The N / N bidentate coordination diamine-based titanium-zirconium-hafnium metal catalyst reported in this invention has the advantages of simple synthesis, readily available raw materials, high product yield, and high catalytic activity, making it particularly suitable for the one-pot synthesis of high-performance bimodal polyethylene. In the presence of a co-catalyst, the catalyst exhibits excellent activity, reaching a maximum of 1.56 × 10⁻⁶. 7 g(polymer)·mol -1 (M)·h -1Therefore, this invention is original and innovative, providing a new direction for the development of polyolefin materials. Summary of the Invention

[0005] The purpose of this invention is to provide a synthesis of a diamine-based titanium-zirconium-hafnium metal catalyst based on N / N two-dentate coordination and its application in the preparation of polyolefin elastomers.

[0006] This invention provides a diamine-based titanium-zirconium-hafnium metal catalyst based on N / N two-dentate coordination, as shown in formula (I):

[0007]

[0008] Where M is selected from titanium, zirconium, and hafnium; R 1 Selected from methyl, ethyl, hydrogen, isopropyl, chlorine, fluorine; R 2 Selected from methyl, ethyl, hydrogen, isopropyl, chlorine, fluorine; R 3 Selected from methyl, methoxy, hydrogen, tert-butyl, R 4 Selected from C1-C6 linear alkyl, phenyl, benzyl, or isopropylphenyl.

[0009] Preferably, the metal catalyst of the present invention is selected from any one of the metal catalysts shown in (II):

[0010]

[0011] This invention provides a method for preparing the above-mentioned diamine-based titanium-zirconium-hafnium metal catalyst based on N / N two-dentate coordination, comprising the following steps:

[0012] Under a nitrogen atmosphere, the metal salt MCl4 was dissolved in 20-80 mL of anhydrous solvent, and 4.0-5.0 molar equivalents of methyl magnesium bromide were added. The reaction was carried out at low temperature for 2 hours under nitrogen protection, followed by the addition of 1 molar equivalent of diamine ligand and the reaction was carried out for 5 hours. After the reaction was completed, the solvent was removed under reduced pressure, and the solution was extracted with a good solvent to obtain the N / N bidentate diamine titanium zirconium hafnium metal catalyst of claim 1.

[0013] In the above preparation method, the anhydrous solvent is selected from one or more of toluene, n-hexane, xylene, and benzene; the good solvent is selected from one or more of n-hexane, toluene, pentane, heptane, and cyclohexane.

[0014] In the above preparation method, the metal salt MCl4 is selected from one of TiCl4, ZrCl4, and HfCl4.

[0015] This invention also provides the application of the above-mentioned diamine titanium zirconium hafnium metal catalyst based on NN two-dentate coordination in olefin polymerization.

[0016] In the above applications, the olefin monomer is one or more of ethylene, propylene, 1-butene, styrene, 1-hexene, norbornene, and 1-octene.

[0017] The diamine-based titanium-zirconium-hafnium metal catalyst based on N / N two-dentate coordination requires a co-catalyst for catalysis. The co-catalyst is one or more of tripentafluorophenylboron, triphenylcarbium tetra(pentafluorophenyl)borate, aluminoxane, alkylaluminum, and alkylaluminum chloride. The aluminoxane is methylaluminoxane, ethylaluminoxane, or isobutylaluminoxane; the alkylaluminum is trimethylaluminum, triethylaluminum, triisobutylaluminum, or tri-n-hexylaluminum; and the alkylaluminum chloride is diethylaluminum chloride, sesqui-diethylaluminum chloride, or ethylaluminum dichloride.

[0018] In the above polymerization reaction, the polymerization temperature is 0-200℃, the polymerization pressure is 0.1-5MPa, and the polymerization solvent is one or more of n-hexane, heptane, pentane, and toluene.

[0019] This invention provides the preparation of a diamine-based titanium-zirconium-hafnium metal catalyst based on N / N bilateral coordination, and its application in catalyzing olefin polymerization. The N / N bilateral coordination-based diamine-based titanium-zirconium-hafnium metal catalyst reported in this invention has the advantages of simple synthesis, readily available raw materials, high product yield, and high catalytic activity, and is particularly suitable for one-pot synthesis of high-performance bimodal polyethylene. The metal catalyst provided by this invention is original and innovative, and can promote the development of my country's high-end polyolefin chemical industry. Attached Figure Description

[0020] Figure 1 The image shows the 1H NMR spectrum of catalyst Hf1.

[0021] Figure 2 This is the 1H NMR spectrum of the catalyst Hf2.

[0022] Figure 3 This is the 1H NMR spectrum of the catalyst Hf3.

[0023] Figure 4 The image shows the 1H NMR spectrum of the catalyst Zr1.

[0024] Figure 5 The GPC spectrum of the polymer prepared in Example 5.

[0025] Figure 6 The GPC spectrum of the polymer prepared in Example 6.

[0026] Figure 7 The GPC spectrum of the polymer prepared in Example 9.

[0027] Figure 8 This is a crystal diagram of the catalyst Hf1. Detailed Implementation

[0028] The present invention is further illustrated by examples, but is not limited thereto. These examples will enable those skilled in the art to gain a more comprehensive understanding of the invention.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0030] In this invention, the N-N bidentate diamine ligands C1-L(2,4,6-Me3-C6H2-NH-C6H4-N(Me)-C6H5), C2-L(C6H5-NH-C6H4-N(Me)-C6H5), and C3-L(2,6-Cl2-C6H3-NH-C6H4-N(Me)-C6H5) are as shown in (Ⅲ), referring to the method in the literature (J.Mol.Catal.A:Chem.2002,182-183,515-523).

[0031]

[0032] The present invention is described below with reference to specific embodiments.

[0033] Example 1: Preparation of catalyst Hf1

[0034] Hafnium tetrachloride (0.352 g, 1.1 mmol) was weighed and added to 10 mL of anhydrous toluene. The mixture was then slowly added to 1.6 mL / 4.8 mmol methyl magnesium bromide solution (3 M) at -40 °C (acetonitrile-liquid nitrogen bath), and stirred for 2 hours. Then, ligand C1-L (0.27 g / 1 mmol) was added, and the reaction was carried out at -40 °C in the dark for 2 hours, followed by a 5-hour reaction at room temperature. After the reaction was complete, the solvent was removed, and the product was extracted with toluene and filtered to give 0.40 g of the product, with a yield of 75%. 1 H NMR (400MHz, C6D6): δ7.02–6.96(m,4H),6.89–6.81(m,4H),6.52(d,J=7.8Hz,1H),6.42(t,J=6.9H z,1H),6.08(d,J=8.2Hz,1H),2.78(s,3H),2.37(s,3H),2.29(s,3H),2.24(s,3H),0.40(s,9H)ppm. 13 C NMR (100MHz, C6D6): δ152.17,149.08,143.56,140.57,136.46,135.28,130.49,130.35,12 9.76,125.48,125.00,120.35,117.91,113.81,62.97,41.88,21.11,18.83ppm.Anal.Calcd for C 25 H32 HfN2:C,55.71;H,5.98;N,5.20.Found:C,55.68;H,5.96;N,5.25.

[0035] Example 2: Preparation of catalyst Hf2

[0036] Hafnium tetrachloride (0.352 g, 1.1 mmol) was weighed and added to 10 mL of anhydrous toluene. Under conditions of –40 °C (acetonitrile-liquid nitrogen bath), 1.6 mL / 4.8 mmol methyl magnesium bromide solution (3 M) was slowly added, and the mixture was stirred for 2 hours. Then, ligand C2-L (0.22 g / 1 mmol) was added, and the reaction was carried out at –40 °C in the dark for 2 hours, followed by a 5-hour reaction at room temperature. After the reaction was complete, the solvent was removed, and the product was extracted with toluene and filtered to obtain 0.42 g of the product, with a yield of 80%. 1 H NMR (400MHz, C6D6): δ7.40–7.31(m,4H),7.13–7.08(m,1H),6.96(t,J=8.0Hz,2H),6.90–6 .80(m,4H),6.48(dd,J=8.0,1.4Hz,1H),6.45–6.38(m,2H),2.69(s,3H),0.40(s,9H)ppm. 13 C NMR (100MHz, C6D6): δ153.91,148.64,146.72,143.83,130.45,129.94,129.53,129 .10,125.74,125.64,124.64,119.97,117.99,114.58,61.85,40.85ppm.Anal.Calcd for C 22 H 26 HfN2:C,53.17;H,5.27;N,5.64.Found:C,53.24;H,5.21;N,5.63.

[0037] Example 3: Preparation of catalyst Hf3

[0038] Hafnium tetrachloride (0.352 g, 1.1 mmol) was weighed and added to 10 mL of anhydrous toluene. The mixture was then slowly added to a 1.6 mL / 4.8 mmol solution of methyl magnesium bromide (3 M) at -40 °C (acetonitrile-liquid nitrogen bath), and stirred for 2 hours. Then, ligand C3-L (0.19 g / 1 mmol) was added, and the reaction was continued at -40 °C in the dark for 2 hours, followed by a 5-hour reaction at room temperature. After the reaction was complete, the solvent was removed, and the product was extracted with toluene and filtered to give 0.36 g of the product, with a yield of 69%. 1H NMR (400MHz, C6D6): δ7.19 (d, J=8.1Hz, 2H), 6.94–6.92 (m, 3H), 6.85–6.81 (m ,2H),6.57–6.40(m,4H),6.09(d,J=9.3Hz,1H),2.88(s,3H),0.51(s,9H)ppm. 13 C NMR (100MHz, C6D6): δ150.94,147.90,144.09,142.87,129.84,129.36,126.85,125 .81,125.04,124.07,120.79,120.46,118.62,114.15,64.79,42.33ppm.Anal.Calcd for C 22 H 24 Cl2HfN2:C,46.70;H,4.28;N,4.95.Found:C,46.78;H,4.25;N,4.90.

[0039] Example 4: Preparation of catalyst Zr1

[0040] Zirconium tetrachloride (0.256 g, 1.1 mmol) was weighed and added to 10 mL of anhydrous toluene. The mixture was then slowly added to 1.6 mL / 4.8 mmol methyl magnesium bromide solution (3 M) at -40 °C (acetonitrile-liquid nitrogen bath), and stirred for 2 hours. Then, ligand C1-L (0.27 g / 1 mmol) was added, and the reaction was carried out at -40 °C in the dark for 2 hours, followed by a 5-hour reaction at room temperature. After the reaction was complete, the solvent was removed, and the product was extracted with toluene and filtered to give 0.46 g of the product, with a yield of 82%. 1 H NMR (400MHz, C6D6): δ7.05–6.99(m,4H),6.92–6.84(m,4H),6.55(dd,J=7.9,1.4Hz,1H),6.47–6.42(m, 1H),6.11(dd,J=8.2,1.3Hz,1H),2.81(s,3H),2.40(s,3H),2.32(s,3H),2.27(s,3H),0.43(s,9H)ppm. 13 C NMR (100MHz, C6D6): δ151.85,148.76,143.24,140.26,136.15,134.96,130.17,130.04 ,129.44,125.16,124.69,120.03,117.59,113.49,62.65,20.79,18.51ppm.Anal.Calcd for C 25 H 32N2Zr: C, 66.47; H, 7.14; N, 6.20. Found: C, 66.50; H, 7.13; N, 6.18.

[0041] Example 5: Hf1-catalyzed ethylene polymerization

[0042] A 100 mL steel reactor equipped with a magnetic induction device was used for the polymerization reaction. 50 mL of toluene was injected using a syringe, and the reactor contents were heated to 80 °C. The reactor was then saturated with ethylene at 25 atm. In a glove box, 5 μmol of catalyst Hf1, 100 μmol of methylaluminoxane MAO, and 10 μmol of triphenylmethyltetra(pentafluorophenyl)borate were added, dissolved in toluene, and transferred to a catalyst storage tube via a syringe. Nitrogen gas (above 30 atm) was then pressurized into the reactor, and the reaction pressure was maintained at 25 atm by continuously introducing ethylene gas during polymerization. After the set reaction time of 2 minutes, 2 mL of ethanol was pressurized into the reactor under nitrogen (above 30 atm). The reactor was cooled and vented. The contents of the reactor were poured into a large amount of ethanol, causing polymer precipitation. The polymer was obtained by filtration, washed with a small amount of ethanol, and finally vacuum dried overnight before weighing. Polymerization activity: 15600 kg·mol⁻¹ -1 (M)·h -1 Polymer M w =3611 / 37kg·mol -1 , M w / M n =1.7 / 2.2.

[0043] Example 6: Hf2-catalyzed ethylene polymerization

[0044] The polymerization process and reaction conditions were the same as in Example 5, and the catalyst used was Hf2. Polymerization activity: 13440 kg·mol⁻¹ -1 (M)·h -1 Polymer M w =3314 / 43kg·mol -1 , M w / M n =2.0 / 2.2.

[0045] Example 7: Hf3-catalyzed ethylene polymerization

[0046] The polymerization process and reaction conditions were the same as in Example 5, and the catalyst used was Hf3. Polymerization activity: 1680 kg·mol⁻¹ -1 (M)·h -1 Polymer M w =2989 / 56kg·mol -1 , M w / M n =1.9 / 2.2.

[0047] Example 8: Zr1-catalyzed ethylene polymerization

[0048] The polymerization process and reaction conditions were the same as in Example 5, and the catalyst used was Zr1. Polymerization activity: 1800 kg·mol⁻¹ -1 (M)·h -1 Polymer M w =3635 / 86kg·mol -1 , M w / M n =1.7 / 2.7.

[0049] Example 9: Hf1-catalyzed copolymerization of ethylene / 1-octene

[0050] A 100 mL steel reactor equipped with a magnetic induction chamber was used for the polymerization reaction. A mixture of 42 mL toluene and 8 mL 1-octene (total 50 mL) was injected using a syringe. The reactor contents were heated to 80 °C, and saturated with ethylene at 25 atm. In a glove box, 5 μmol of catalyst Hf1, 100 μmol of methylaluminoxane MAO, and 10 μmol of triphenylmethyltetra(pentafluorophenyl)borate were added, dissolved in toluene, and transferred to a catalyst storage tube via a syringe. Nitrogen gas (above 30 atm) was then pressurized into the reactor. During polymerization, the reaction pressure was maintained at 25 atm by continuously introducing ethylene gas. After the set reaction time of 2 minutes, 2 mL of ethanol was pressurized into the reactor under nitrogen (above 30 atm). After cooling, the reactor was vented, and the contents were poured into a large amount of ethanol. The polymer precipitated, was filtered, washed with a small amount of ethanol, and finally vacuum-dried overnight and weighed. Polymerization activity: 4320 kg·mol⁻¹ -1 (Zr)·h -1 Polymer M w =1316 / 29kg·mol -1 , M w / M n =2.1 / 1.8, the copolymer contains 1.2 mmol of 1-octene.

[0051] Example 10: Hf1-catalyzed copolymerization of ethylene / 1-octene

[0052] The polymerization process and conditions were the same as in Example 9, except that 34 mL of toluene and 16 mL of 1-octene were used. Polymerization activity: 2580 kg·mol⁻¹ -1 (Hf)·h -1 Polymer M w =29kg·mol -1 , M w / M n=2.1, the content of 1-octene in the copolymer is 3.2 mmol%.

[0053] Example 11: Hf1-catalyzed copolymerization of ethylene / 1-octene

[0054] The polymerization process and conditions were the same as in Example 9, except that 27 mL of toluene and 23 mL of 1-octene were used. Polymerization activity: 2280 kg·mol⁻¹ -1 (Hf)·h -1 Polymer M w =27kg·mol -1 , M w / M n =1.9, the copolymer contains 4.2 mmol% 1-octene.

[0055] Example 12: Hf2-catalyzed copolymerization of ethylene / 1-octene

[0056] The polymerization process and reaction conditions were the same as in Example 9, and the catalyst used was Hf2. Polymerization activity: 4020 kg·mol⁻¹ -1 (M)·h -1 Polymer M w =2286 / 21kg·mol -1 , M w / M n =3.0 / 2.3, the content of 1-octene in the copolymer is 3.2 mmol%.

[0057] Example 13: Hf3-catalyzed copolymerization of ethylene / 1-octene

[0058] The polymerization process and reaction conditions were the same as in Example 9, and the catalyst used was Hf3. Polymerization activity: 780 kg·mol⁻¹ -1 (M)·h -1 , M w =1694 / 25kg·mol -1 , M w / M n =3.6 / 2.0, the copolymer contains 1.2 mmol of 1-octene.

[0059] Example 14: Zr1-catalyzed copolymerization of ethylene / 1-octene

[0060] The polymerization process and reaction conditions were the same as in Example 9, and the catalyst used was Zr1. Polymerization activity: 960 kg·mol⁻¹ -1 (M)·h -1 , M w =2152 / 35kg·mol -1 , M w / M n=2.8 / 2.2, the copolymer contains 1.2 mmol of 1-octene.

Claims

1. A class of N-N bidentate coordinated diamine-based titanium-zirconium-hafnium metal catalysts, the structure of which is shown in formula (I): in, M is selected from titanium, zirconium, and hafnium; R 1 Selected from methyl, ethyl, hydrogen, isopropyl, chlorine, fluorine; R 2 Selected from methyl, ethyl, hydrogen, isopropyl, chlorine, fluorine; R 3 Selected from methyl, methoxy, hydrogen, tert-butyl, R 4 Selected from C1-C6 linear alkyl, phenyl, benzyl, or isopropylphenyl.

2. The catalyst according to claim 1, characterized in that, The catalyst is at least one of the following:

3. The preparation method of the N / N bidentate coordinated diamine titanium zirconium hafnium metal catalyst according to claims 1-2 comprises the following steps: under a nitrogen atmosphere, dissolving the metal salt MCl4 in 20-80 mL of anhydrous solvent, adding 4.0-5.0 molar equivalents of methyl magnesium bromide, reacting at low temperature for 2 hours under nitrogen protection, and then adding 1 molar equivalent of diamine ligand and reacting for 5 hours; after the reaction is completed, removing the solvent under reduced pressure, extracting with a good solvent, and obtaining the N / N bidentate coordinated diamine titanium zirconium hafnium metal catalyst according to claim 1.

4. The preparation method according to claim 3, characterized in that: The anhydrous solvent is selected from one or more of toluene, n-hexane, xylene, and benzene; the good solvent is selected from one or more of n-hexane, toluene, pentane, heptane, and cyclohexane.

5. The preparation method according to claim 3, characterized in that: The metal salt MCl4 is selected from one of TiCl4, ZrCl4, and HfCl4.

6. A method for olefin polymerization, characterized in that: The catalyst used is the N-N two-dentate coordinated diamine titanium-zirconium-hafnium metal catalyst as described in claims 1-2.

7. The method according to claim 6, characterized in that: The olefin monomer is one or more of ethylene, propylene, 1-butene, styrene, 1-hexene, norbornene, and 1-octene.

8. The method according to claim 6, characterized in that: The N / N two-dentate coordinated diamine titanium zirconium hafnium metal catalyst requires the use of a co-catalyst for catalysis. The co-catalyst is one or more of tripentafluorophenylboron, triphenylcarbium tetra(pentafluorophenyl)borate, aluminoxane, alkylaluminum and alkylaluminum chloride.

9. The method according to claim 8, characterized in that: The aluminum oxane is methylaluminoxane, ethylaluminoxane, or isobutylaluminoxane; the alkylaluminum is trimethylaluminum, triethylaluminum, triisobutylaluminum, or tri-n-hexylaluminum; and the alkylaluminum chloride is diethylaluminum chloride, sesqui-diethylaluminum chloride, or ethylaluminum dichloride.

10. The method according to claim 6, characterized in that: The polymerization temperature is 0-200℃, the polymerization pressure is 0.1-5MPa, and the solvent used for polymerization is one or more of n-hexane, n-heptane, n-pentane, and toluene.

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