Bimetallic compound based on hydrazide pyrene skeleton and preparation method and application thereof

Abstract

The invention relates to a bimetallic compound based on a hydrazide pyrene skeleton and a preparation method and application thereof. The bimetallic compound based on the hydrazide pyrene skeleton has the structural characteristics as shown in the following formula (I). The bimetallic compound based on the hydrazide pyrene skeleton is higher in catalytic activity under a high-temperature condition, and prepared polyolefin is high in molecular weight and high in isotacticity. # imgabs0 #

Description

Technical Field

[0001] The present application relates to the technical field of polyolefin preparation, and in particular to a bimetallic compound based on a hydrazide pyrene skeleton, and a preparation method and application thereof. Background Art

[0002] Polyolefin is a kind of polymer material made by olefin polymerization. It has good mechanical properties and high chemical stability and has been widely used. In the production process of polyolefin, the catalytic performance of the catalyst determines the performance and cost of the polyolefin material. However, traditional catalysts for polyolefin polymerization usually have low activity at high temperatures and cannot catalyze the reaction well, making it difficult to prepare high molecular weight and high isotactic polyolefin materials under high temperature conditions.

[0003] A method provides a bimetallic catalyst based on an acylhydrazonepyrene skeleton (the structure is shown in the following formula (1)). The catalytic activity of the catalyst is improved by introducing the acylhydrazonepyrene skeleton. At the same time, the catalytic activity of the catalyst is improved by adjusting the structure and central metal of the catalyst, and the spatial and electronic effects of the catalyst are changed. The catalyst can be used to prepare polyolefin products with excellent anti-yellowing performance, high glass transition temperature, high isotacticity and ultra-high molecular weight. However, the catalytic activity of the catalyst under high temperature conditions needs to be further improved.

[0004] Summary of the invention

[0005] Based on this, the present application provides a bimetallic compound based on a hydrazidepyrene skeleton having higher catalytic activity under high temperature conditions, and having a high molecular weight and high isotacticity of the prepared polyolefin, as well as a preparation method and application thereof.

[0006] In the first aspect of the present application, a bimetallic compound based on a hydrazide pyrene skeleton is provided, having the structural characteristics shown in the following formula (I):

[0007]

[0008] in,

[0009] R1 and R2 each independently include C1-C24 alkyl, C6-C30 aryl, C3-C18 cycloalkyl, C5-C10 cycloalkenyl or C6-C30 aryl substituted with C1-C5 alkoxy;

[0010] Each occurrence of M independently comprises a Group IVB metal element;

[0011] Each occurrence of X independently includes halogen, C1-C16 alkyl or -C1-C5 alkyl-C6-C16 aryl.

[0012] In one embodiment, R1 and R2 each independently include C1-C10 alkyl, C6-C16 aryl, C3-C8 cycloalkyl, C5-C8 cycloalkenyl or C1-C3 alkoxy substituted C6-C16 aryl. Further, R1 and R2 each independently include C1-C6 alkyl, C6-C14 aryl, C3-C6 cycloalkyl, C5-C8 cycloalkenyl or C1-C3 alkoxy substituted C6-C14 aryl. Further, R1 and R2 each independently include phenyl, p-methylphenyl, p-methoxyphenyl, cyclopropyl, cyclohexyl, cyclooctyl, cyclopentadienyl or anthracenyl.

[0013] In one embodiment, the bimetallic compound based on hydrazide pyrene skeleton has one of the following structural features:

[0014]

[0015] In one embodiment, each occurrence of M independently comprises titanium, zirconium or hafnium.

[0016] In one embodiment, each occurrence of X independently comprises halogen, C1-C10 alkyl or -C1-C3 alkyl-C6-C10 aryl. Further, each occurrence of X independently comprises halogen, C1-C8 alkyl or -C1-C3 alkyl-C6-C8 aryl. Further, each occurrence of X independently comprises halogen, C1-C6 alkyl or -C1-C2 alkyl-C6-C8 aryl. Further, each occurrence of X independently comprises methyl, chlorine or benzyl.

[0017] The second aspect of the present application provides a method for preparing the bimetallic compound based on the hydrazide pyrene skeleton described in the first aspect, comprising the following steps:

[0018] In the presence of a hydrogen extraction agent, the ligand compound represented by formula (II) is subjected to a complexation reaction with the metal salt MX4;

[0019]

[0020] In one embodiment, the method for preparing the bimetallic compound based on the hydrazide pyrene skeleton has one or more of the following characteristics:

[0021] (1) The metal salt MX4 includes titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride, tetrabenzyl hafnium, tetra(ethylmethyl)aminozirconium, titanium tetrabromide, zirconium tetrabromide or hafnium tetrabromide;

[0022] (2) The molar ratio of the ligand compound represented by formula (II) to the metal salt MX4 is 1:(2-5);

[0023] (3) The molar ratio of the ligand compound represented by formula (II) to the hydrogen extraction agent is 1:(4-8);

[0024] (4) The hydrogen extraction reagent includes one or more of alkyl lithium, phenyl lithium, sodium hydride, elemental sodium and Grignard reagent;

[0025] (5) The conditions of the complexation reaction include: temperature of 20°C to 60°C and time of 1 h to 4 h.

[0026] In one embodiment, the preparation method of the ligand compound represented by formula (II) comprises the following steps:

[0027] Compound A is selected from R1-COOCH3 or R2-COOCH3;

[0028] Compound B is selected from

[0029] Compound C is selected from

[0030] Performing a first reaction between hydrazine hydrate and compound A to prepare compound B;

[0031] In the presence of a catalyst and a base, compound C and compound B are subjected to a second reaction to prepare a ligand compound represented by formula (II).

[0032] Furthermore, the conditions of the first reaction include: temperature of 30°C to 80°C, and time of 1h to 12h.

[0033] Further, compound A includes one or more of methyl benzoate, methyl n-butyrate, methyl cyclohexylcarboxylate, methyl cyclopropylcarboxylate, methyl 4-methylbenzoate, methyl 4-methoxycarboxylate, methyl 3,4,5-trimethylcarboxylate, methyl 3,4,5-trimethoxycarboxylate, methyl 3,4,5-trichlorocarboxylate, methyl 4-methylcyclohexylcarboxylate, methyl 3,4,5-trimethylcyclohexylcarboxylate, methyl 3,4,5-trimethoxycyclohexylcarboxylate, methyl tetrahydrothiopyran-4-carboxylate, methyl 9-carboxylate anthracene and methyl cyclooctanecarboxylate.

[0034] Furthermore, the molar ratio of compound A to hydrazine in hydrazine hydrate is 1:(1-1.5).

[0035] Furthermore, the conditions of the second reaction include: temperature of 25°C to 60°C, and time of 2h to 5h.

[0036] Further, the catalyst includes 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate.

[0037] Optionally, the base includes one or more of triethylamine, N,N-diisopropylethylamine and pyridine.

[0038] Furthermore, the molar ratio of compound C, the catalyst, the base and compound B is 1:(0.2-0.5):(2-6):(2-4).

[0039] The third aspect of the present application provides the use of the bimetallic compound based on the hydrazide pyrene skeleton described in the first aspect as a catalyst in the preparation of polyolefins.

[0040] In a fourth aspect of the present application, a method for preparing a polyolefin is provided, comprising the following steps:

[0041] In the presence of the bimetallic compound based on the hydrazide pyrene skeleton described in the first aspect, olefin monomers are polymerized in a solvent to prepare polyolefin.

[0042] In one embodiment, the concentration of the bimetallic compound based on hydrazide pyrene skeleton in the solvent is 0.1 ppm to 50 ppm.

[0043] In one embodiment, the solvent further includes a co-catalyst; further optionally, the co-catalyst includes one or more of alkyl aluminum and borate.

[0044] In one embodiment, the polymerization reaction temperature is 10°C to 300°C.

[0045] In one embodiment, the polymerization reaction pressure is 0.1 MPa to 20 MPa.

[0046] In one embodiment, the solvent includes one or more of an alkane solvent, a cycloalkane solvent and an aromatic solvent.

[0047] The catalytic activity of traditional bimetallic catalysts based on acylhydrazonepyrene skeletons is difficult to achieve the expected under high temperature conditions. The possible reasons are: in the compound structure, the electron cloud density of the metal center of the complex is uneven, and the non-rigid structure connected by the coordination groups, the condensed ring only acts as an electron-donating group, and it is difficult to play a role in stabilizing the skeleton.

[0048] The present application provides a bimetallic compound based on a hydrazide pyrene skeleton, which introduces pyrene as a rigid center, and at the same time, N on the condensed ring is complexed with the metal to form a six-membered ring rigid structure with pyrene, thereby improving the stability of the compound skeleton, significantly improving the high temperature resistance, and thus exerting better polyolefin catalytic activity under high temperature conditions. At the same time, the amine in the hydrazide is connected to the active center metal, and due to the electron-pulling effect of the carbonyl group, the electron cloud density of the active center is symmetrical and more conducive to the improvement of the catalytic activity of the compound. The combination of the two makes the compound have a higher polyolefin catalytic activity under high temperature conditions, and the prepared polyolefin material has a higher molecular weight and a higher isotacticity, and also has good anti-yellowing performance and a higher glass transition temperature, and has a wide range of application prospects.

[0049] In addition, the polyolefin material prepared by using the bimetallic compound based on the hydrazide pyrene skeleton as a catalyst also has the characteristics of narrow molecular weight distribution and high hexene insertion rate. DETAILED DESCRIPTION

[0050] The following is a further detailed description of the bimetallic compound based on hydrazide pyrene skeleton and its preparation method and application of the present application in conjunction with specific examples. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0052] As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.

[0053] In this application, "first aspect", "second aspect", "third aspect", "fourth aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0054] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0055] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0056] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0057] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0058] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control.

[0059] Room temperature in this application generally refers to 25±5°C.

[0060] In some examples of the present application, a bimetallic compound based on a hydrazide pyrene skeleton is provided, having the structural features shown in the following formula (I):

[0061]

[0062] in,

[0063] R1 and R2 each independently include C1-C24 alkyl, C6-C30 aryl, C3-C18 cycloalkyl, C5-C10 cycloalkenyl or C6-C30 aryl substituted by C1-C5 alkoxy; it can be understood that R1 and R2 can be the same or different, in some examples, R1 and R2 are the same;

[0064] Each occurrence of M independently comprises a Group IVB metal element;

[0065] Each occurrence of X independently includes halogen, C1-C16 alkyl or -C1-C5 alkyl-C6-C16 aryl.

[0066] In some examples, R1 and R2 each independently include C1-C10 alkyl, C6-C16 aryl, C3-C8 cycloalkyl, C5-C8 cycloalkenyl or C1-C3 alkoxy substituted C6-C16 aryl. Further, R1 and R2 each independently include C1-C6 alkyl, C6-C14 aryl, C3-C6 cycloalkyl, C5-C8 cycloalkenyl or C1-C3 alkoxy substituted C6-C14 aryl. Further, R1 and R2 each independently include phenyl, p-methylphenyl, p-methoxyphenyl, cyclopropyl, cyclohexyl, cyclooctyl, cyclopentadienyl or anthracenyl.

[0067] In some of the examples, the bimetallic compound based on the hydrazide pyrene skeleton has one of the following structural features:

[0069]

[0070] In some examples, each occurrence of M independently includes titanium, zirconium, or hafnium.

[0071] In some of these examples, each occurrence of X independently includes halogen, C1-C10 alkyl, or -C1-C3 alkyl-C6-C10 aryl. Further, each X independently includes halogen, C1-C8 alkyl, or -C1-C3 alkyl-C6-C8 aryl. Further, each X independently includes halogen, C1-C6 alkyl, or -C1-C2 alkyl-C6-C8 aryl. Specifically, each X independently includes methyl, chlorine, or benzyl.

[0072] Specifically, the bimetallic compound based on the hydrazide pyrene skeleton has one of the following structural characteristics:

[0073]

[0074] In some other examples of the present application, a method for preparing the bimetallic compound based on the hydrazide pyrene skeleton as described above is provided, comprising the following steps:

[0075] In the presence of a hydrogen extraction agent, the ligand compound represented by formula (II) is subjected to a complexation reaction with the metal salt MX4;

[0076]

[0077] In some examples, the metal salt MX4 includes titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride, tetrabenzylhafnium, tetra(ethylmethyl)zirconium amine, titanium tetrabromide, zirconium tetrabromide, or hafnium tetrabromide.

[0078] In some examples, the molar ratio of the ligand compound represented by formula (II) to the metal salt MX4 is 1:(2-5). Specifically, the molar ratio includes but is not limited to: 1:2, 1:2.5, 1:3, 1:3.5, 14, 1:4.5, 1:5 or a range between any two of the foregoing.

[0079] In some examples, the molar ratio of the ligand compound represented by formula (II) to the hydrogen extraction agent is 1:(4-8). Specifically, the molar ratio includes but is not limited to: 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8 or a range between any two of the foregoing.

[0080] In some examples, the hydrogenation reagent includes one or more of alkyl lithium, phenyl lithium, sodium hydride, elemental sodium and Grignard reagent. Further, the hydrogenation reagent includes one or more of n-butyl lithium, n-methyl lithium and n-hexyl lithium.

[0081] In some of the examples, the conditions of the complexation reaction include: a temperature of 20° C. to 60° C., and a time of 1 h to 4 h.

[0082] In some of the examples, the preparation method of the ligand compound represented by formula (II) comprises the following steps:

[0083] Compound A is selected from R1-COOCH3 or R2-COOCH3;

[0084] Compound B is selected from

[0085] Compound C is selected from

[0086] 1) subjecting hydrazine hydrate and compound A to a first reaction to prepare compound B;

[0087] 2) In the presence of a catalyst and a base, compound C and compound B are subjected to a second reaction to prepare a ligand compound represented by formula (II).

[0088] In some of the examples, in step 1), the conditions of the first reaction include: temperature of 30° C. to 80° C., and time of 1 h to 12 h.

[0089] In some of the examples, in step 1), compound A includes one or more of methyl benzoate, methyl n-butyrate, methyl cyclohexylcarboxylate, methyl cyclopropylcarboxylate, methyl 4-methylbenzoate, methyl 4-methoxycarboxylate, methyl 3,4,5-trimethylcarboxylate, methyl 3,4,5-trimethoxycarboxylate, methyl 3,4,5-trichlorocarboxylate, methyl 4-methylcyclohexylcarboxylate, methyl 3,4,5-trimethylcyclohexylcarboxylate, methyl 3,4,5-trimethoxycyclohexylcarboxylate, methyl tetrahydrothiopyran-4-carboxylate, methyl 9-carboxylate anthracene and methyl cyclooctanecarboxylate.

[0090] In some examples, in step 1), the molar ratio of compound A to hydrazine in hydrazine hydrate is 1:(1-1.5). Specifically, the molar ratio includes but is not limited to: 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5 or a range between any two of the foregoing.

[0091] In some examples, in step 1), the solvent for the first reaction includes one or more of methanol, ethanol, ethylene glycol and glycerol.

[0092] In some of the examples, in step 2), the conditions of the second reaction include: temperature of 25°C to 60°C, and time of 2h to 5h.

[0093] In some examples, in step 2), the catalyst includes 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU).

[0094] In some examples, in step 2), the base includes one or more of triethylamine, N,N-diisopropylethylamine (DIPEA) and pyridine.

[0095] In some examples, in step 2), the solvent for the second reaction includes one or more of N,N-dimethylacetamide (DMF), acetonitrile, dimethyl sulfoxide (DMSO) and tetrahydrofuran.

[0096] In some examples, in step 2), the molar ratio of compound C, the catalyst, the base and compound B is 1:(0.2-0.5):(2-6):(2-4).

[0097] Some other examples of the present application provide the use of the bimetallic compound based on the hydrazide pyrene skeleton as described above as a catalyst in the preparation of polyolefins.

[0098] Some other examples of the present application provide a method for preparing polyolefin, comprising the following steps:

[0099] In the presence of the bimetallic compound based on hydrazide pyrene skeleton as described above, olefin monomers are polymerized in a solvent to prepare polyolefin.

[0100] In some examples, the olefin monomer includes an α-olefin monomer.

[0101] In some examples, the concentration of the bimetallic compound based on hydrazide pyrene skeleton in the solvent is 0.1ppm to 50ppm. Specifically, the concentration includes but is not limited to: 0.1ppm, 1ppm, 5ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm, 50ppm or a range between any two of the foregoing.

[0102] In some examples, the solvent also includes a co-catalyst. Further, the co-catalyst includes one or more of alkyl aluminum and borate.

[0103] Without limitation, the alkyl aluminum includes aluminoxane or modified aluminoxane of a C1-C10 alkyl group. In some examples, the alkyl aluminum includes tert-butyl aluminoxane. Further, the molar ratio (Al / M) of the metal Al in the alkyl aluminum to the metal M in the compound represented by formula (I) is (10-200):1.

[0104] Without limitation, the borate includes one or more of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, trispentafluorophenyl borate and trityltetrakis(pentafluorophenyl)borate, and in some examples, the borate includes trispentafluorophenyl borate. Further, the molar ratio of the element B in the borate to the metal M in the compound shown in formula I is B / M (0-30):1.

[0105] In some examples, the polymerization temperature is 10°C to 300°C. Specifically, the polymerization temperature includes, but is not limited to, 10°C, 50°C, 80°C, 100°C, 120°C, 150°C, 170°C, 200°C, 230°C, 250°C, 270°C, 300°C, or a range between any two of the foregoing. Further, the polymerization temperature is 80°C to 250°C.

[0106] In some examples, the polymerization reaction pressure is 0.1 MPa to 20 MPa. Specifically, the polymerization reaction pressure includes, but is not limited to, 0.1 MPa, 1 MPa, 3 MPa, 5 MPa, 8 MPa, 10 MPa, 13 MPa, 15 MPa, 17 MPa, 20 MPa, or a range between any two of the foregoing. Further, the polymerization reaction pressure is 1 MPa to 8 MPa.

[0107] In some examples, the solvent includes one or more of an alkane solvent, a cycloalkane solvent, and an aromatic solvent. Further, the solvent includes one or more of toluene, heptane, hexane, Isopar E, and cyclohexane.

[0108] For experimental parameters not specified in the following specific embodiments, reference is made to the instructions given in the present application document, and reference may also be made to experimental manuals in the art or other experimental methods known in the art, or to experimental conditions recommended by manufacturers.

[0109] The raw materials and reagents involved in the following specific examples can be obtained from commercial sources, or can be prepared by those skilled in the art according to known methods.

[0110] The sources of the main materials and reagents used in the following examples are as follows:

[0111] Hydrazine hydrate: AR, Aladdin;

[0112] 9-Methylcarboxylate anthracene: AR, Innochem;

[0113] Methyl tetrahydrothiopyran-4-carboxylate: AR, Innochem;

[0114] Methyl 4-methoxyformate: AR, Innochem;

[0115] Methyl cyclohexylcarboxylate: AR, Innochem;

[0116] Methyl benzoate: AR, Innochem;

[0117] HATU: AR, Innochem;

[0118] DIPEA: AR, Aladdin;

[0119] Triethylamine: AR, Aladdin;

[0120] Pyridine: AR, Aladdin;

[0121] 4-methoxyaniline: AR, Aladdin;

[0122] Ethanol: AR, Aladdin;

[0123] Methanol: AR, Aladdin;

[0124] Tetrahydrofuran: AR, Innochem;

[0125] Ethyl acetate: AR, Aldrich;

[0126] Petroleum ether: AR, Aldrich;

[0127] Anhydrous sodium sulfate: AR, Innochem;

[0128] Silicone: AR, Aladdin;

[0129] TiCl4: Tokyo Chemical Industry Co., Ltd.;

[0130] ZrCl4: Tokyo Chemical Industry Co., Ltd.;

[0131] HfCl4: Tokyo Chemical Industry Co., Ltd.;

[0132] Trispentafluorophenyl boron salt: AR, Aladdin;

[0133] Zirconium phenoxyimide: AR, Aladdin;

[0134] Isopar E: ExxonMobil Corporation;

[0135] Tert-butylaluminoxane (MAO): Albemarle;

[0136] Ethylene: 99.9%, Beijing Yanshan Petrochemical Company;

[0137] 1-Hexene: 98%, Beijing Yanshan Petrochemical Company.

[0138] The synthetic route of intermediate C is as follows:

[0139]

[0140] The synthesis method is as follows:

[0141] (1) Compound C1 (627 g) was placed in a 2L reaction bottle, and 500 mL of toluene was added. After stirring and dissolving, 324 g of Pd2(dba), 24 g of 4,5-bis(diphenylphosphino-9,9-dimethylxanthene) and 500 g of sodium tert-butoxide were added, and the mixture was stirred at room temperature for 30 min. Compound C2 (37 g) was added, and the mixture was reacted at 100°C for 3 h, and then extracted with water for 3 times. 160 g of hydrogen bromide was added to the reaction solution, and saturated sodium bicarbonate solution was added until the pH was neutral. The aqueous phase was removed and the organic phase was retained. The solvent was dried and then passed through a column (petroleum ether: ethyl acetate = 10:1) to obtain 450 g of the final product C3.

[0142] The NMR data of compound C3 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ7.83 (s, 4H), 4.24 (s, 2H), 1.31 (s, 18H).

[0143] (2) Compound C3 (450 g) was placed in a 2 L reaction bottle, and 500 mL of THF was added. After stirring to dissolve, 507 g of methyl iodide was added. After reacting at room temperature for 3 h, the solvent was dried to obtain 498 g of the final product C4.

[0144] The NMR data of compound C4 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ7.83 (s, 4H), 2.24 (s, 12H), 1.31 (s, 18H).

[0145] (3) Compound C4 (498 g) was placed in a 2 L reaction bottle, 1,3-dimethyl-2-imidazolidinone (500 mL) and cyanide (157 g) were added, and the mixture was reacted at 220°C for 3 h. Then, 60 g of (Fe(NH4)2(SO4)2)·6H2O was added, and after stirring to dissolve, 324 g of Pd2(dba), 24 g of Xant phos and 500 g of sodium tert-butoxide were added. The mixture was reacted at 80°C for 3 h, and washed with dichloromethane for 3 times. The solvent was drained and the mixture was passed through a column to obtain 400 g of solid C.

[0146] The NMR data of compound C are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ7.83 (s, 4H), 4.36 (s, 1H), 2.11 (s, 12H), 1.31 (s, 18H).

[0147] Example 1 Preparation of Metal Complex E1

[0148] The ligand and metal complex E1 were prepared according to the following general route:

[0149]

[0150] (1) Dissolve hydrazine hydrate (50 g, 1 mol) and compound A1 (136 g, 1 mol) in ethanol (500 mL) and turn on the magnetic stirring to completely dissolve the reactants in the solvent. Set the temperature to 30°C and react for 1 h. After the reaction is completed, cool and solid will precipitate. After standing overnight, filter and dry to obtain compound B1 (81.86 g, 60%).

[0151] The NMR data of compound B1 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ7.58 (s, 2H), 7.30 (s, 3H), 7.07 (s, 1H), 3.71 (s, 2H).

[0152] (2) Compound C (48.8 g, 0.1 mol) and B1 (26.8 g, 0.2 mol) were added to DMF, and triethylamine (20.2 g, 0.2 mol) was added after stirring to dissolve. HATU (7.6 g, 0.02 mol) was added at 25°C, and the mixture was stirred for 2 h. The mixture was washed with water, extracted with ethyl acetate, dried, filtered, and concentrated under reduced pressure to obtain a crude compound D1, which was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 12: 1 (v / v)) to obtain compound D1 (25 g, 34%).

[0153] The NMR data of compound D1 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ8.12 (s, 4H), 7.98 (s, 10H), 4.05 (s, 4H), 2.42 (s, 12H), 1.31 (s, 18H).

[0154] (3) Anhydrous and oxygen-free operation was performed in a glove box. Compound D1 (7 g, 0.01 mol) was placed in a reaction bottle, toluene (100 mL) was added and stirred to dissolve, 1.6 M n-methyllithium (35 mL, 0.056 mol) was slowly added dropwise, and stirred at room temperature for 1 h. TiCl4 (5.31 g, 0.028 mol) was added and reacted for 3 h. After the reaction was completed, the mixture was filtered, the filtrate was drained, n-hexane was added for washing, and a solid product was obtained by filtration, which was recorded as metal complex E1.

[0155]

[0156] Example 2 Preparation of Metal Complex E2

[0157] The ligand and metal complex E2 were prepared according to the following general route:

[0158]

[0159] (1) Dissolve hydrazine hydrate (75 g, 1.5 mol) and compound A2 (142 g, 1 mol) in methanol (500 mL) and turn on the magnetic stirring to allow the reactants to completely dissolve in the solvent. Set the temperature to 80 °C and react for 5 h. After the reaction is completed, cool and solid will precipitate. After standing overnight, filter and dry to obtain compound B2 (129.86 g, 90%).

[0160] The NMR data of compound B2 are as follows: 1 H NMR(CDCl3,500MHz,TMS)δ,7.07(s,1H),3.71(s,2H),2.71(s,1H),1.47(s,8H)1.43(s,2H).

[0161] (2) Compound C (48.8 g, 0.1 mol) and B2 (56 g, 0.4 mol) were added to DMSO, and triethylamine (60.2 g, 0.6 mol) was added after stirring to dissolve. HATU (19 g, 0.05 mol) was added at 40°C, and the mixture was stirred for 3 h. The mixture was washed with water, extracted with ethyl acetate, dried, filtered, and concentrated under reduced pressure to obtain a crude compound D2, which was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 12: 1 (v / v)) to obtain compound D2 (60 g, 82%).

[0162] The NMR data of compound D2 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ8.12 (s, 4H), 4.05 (s, 4H), 3.86 (s, 2H), 2.42 (s, 12H), 1.31 (s, 18H), 1.19 (s, 10H).

[0163] (3) Anhydrous and oxygen-free operation was performed in a glove box. Compound D2 (19 g, 0.026 mol) was placed in a reaction bottle, benzene (100 mL) was added and stirred to dissolve, 1.6 M n-hexyllithium (89.37 mL, 0.143 mol) was slowly added dropwise, the temperature was set to 50°C, ZrCl4 (18.51 g, 0.078 mol) was added, and the reaction was carried out for 1 h. After the reaction was completed, the filtrate was filtered, the filtrate was drained, n-hexane was added for washing, and the solid product was obtained by filtration, which was recorded as metal complex E2.

[0164]

[0165] Example 3 Preparation of Metal Complex E3

[0166] The ligand and metal complex E3 were prepared according to the following general route:

[0167]

[0168] (1) Hydrazine hydrate (60 g, 1.2 mol) and compound A3 (124 g, 1 mol) were dissolved in ethylene glycol (500 mL) and magnetic stirring was turned on to allow the reactants to completely dissolve in the solvent. The temperature was set to 60°C and the reaction was carried out for 5 h. After the reaction was completed, solid was precipitated by cooling. After standing overnight, the solid was filtered and dried to obtain compound B3 (105.86 g, 85%).

[0169] The NMR data of compound B3 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ, 7.47 (s, 1H), 6.50 (s, 1H), 6.35 (s, 1H), 2.71 (s, 2H).

[0170] (2) Compound C (48.8 g, 0.1 mol) and B3 (37.2 g, 0.3 mol) were added to acetonitrile, and triethylamine (40.2 g, 0.4 mol) was added after stirring to dissolve. HATU (11.4 g, 0.03 mol) was added at 60°C, and the mixture was stirred for 3 h. The mixture was washed with water, extracted with ethyl acetate, dried, filtered, and concentrated under reduced pressure to obtain a crude compound D3, which was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 12: 1 (v / v)) to obtain compound D3 (56 g, 80%).

[0171] The NMR data of compound D3 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ8.12 (s, 4H), 4.05 (s, 4H), 3.86 (s, 2H), 2.42 (s, 12H), 1.31 (s, 18H), 1.19 (s, 10H).

[0172] (3) Anhydrous and oxygen-free operation was performed in a glove box. Compound D3 (18.2 g, 0.026 mol) was placed in a reaction bottle, toluene (100 mL) was added and stirred to dissolve, 1.6 M n-hexyllithium (89.37 mL, 0.143 mol) was slowly added dropwise, and stirred at room temperature for 1 h. HfCl4 (27.23 g, 0.085 mol) was added and reacted for 2 h. After the reaction was completed, the mixture was filtered, the filtrate was drained, n-hexane was added for washing, and a solid product was obtained by filtration, which was recorded as metal complex E3.

[0173]

[0174] Example 4 Preparation of Metal Complex E4

[0175] The ligand and metal complex E4 were prepared according to the following general route:

[0176]

[0177] (1) Hydrazine hydrate (60 g, 1.2 mol) and compound A4 (166 g, 1 mol) were dissolved in ethanol (500 mL) and magnetic stirring was turned on to allow the reactants to completely dissolve in the solvent. The temperature was set to 80°C and the reaction was carried out for 5 h. After the reaction was completed, solid was precipitated by cooling. After standing overnight, the solid was filtered and dried to obtain compound B4 (149 g, 89%).

[0178] The NMR data of compound B4 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ, 7.47 (s, 4H), 6.50 (s, 1H), 6.35 (s, 1H), 2.71 (s, 3H).

[0179] (2) Compound C (48.8 g, 0.1 mol) and B4 (32.2 g, 0.2 mol) were added to acetonitrile, and triethylamine (40.2 g, 0.4 mol) was added after stirring to dissolve. HATU (11.4 g, 0.03 mol) was added at 60°C, and the mixture was stirred for 3 h. The mixture was washed with water, extracted with ethyl acetate, dried, filtered, and concentrated under reduced pressure to obtain a crude compound D4, which was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 12: 1 (v / v)) to obtain compound D4 (50 g, 64%).

[0180] The NMR data of compound D4 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ 8.12 (s, 12H), 4.05 (s, 4H), 2.71 (s, 3H), 2.42 (s, 12H), 1.31 (s, 18H).

[0181] (3) Anhydrous and oxygen-free operation was performed in a glove box. Compound D4 (20 g, 0.026 mol) was placed in a reaction bottle, benzene (100 mL) was added and stirred to dissolve, 1.6 M n-hexyl lithium (89.37 mL, 0.143 mol) was slowly added dropwise, and stirred at room temperature for 1 h. The temperature was set to 60°C, tetrabenzyl hafnium (42.35 g, 0.078 mol) was added, and the reaction was continued for 1 h. After the reaction was completed, the mixture was filtered, the filtrate was drained, n-hexane was added for washing, and the solid product was obtained by filtration, which was recorded as metal complex E4.

[0182]

[0183] Example Preparation of Metal Complex E5

[0184] The ligand and metal complex E5 were prepared according to the following general route:

[0185]

[0186] (1) Hydrazine hydrate (60 g, 1.2 mol) and compound A5 (236 g, 1 mol) were dissolved in ethanol (500 mL) and magnetic stirring was turned on to allow the reactants to completely dissolve in the solvent. The temperature was set to 80°C and the reaction was carried out for 5 h. After the reaction was completed, solid was precipitated by cooling. After standing overnight, the solid was filtered and dried to obtain compound B5 (189 g, 80%).

[0187] The NMR data of compound B5 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ, 7.67 (s, 4H), 7.47 (s, 4H), 7.30 (s, 1H), 6.50 (s, 1H), 6.35 (s, 1H).

[0188] (2) Compound C (48.8 g, 0.1 mol) and B5 (56.2 g, 0.2 mol) were added to acetonitrile, and triethylamine (40.2 g, 0.4 mol) was added after stirring to dissolve. HATU (11.4 g, 0.03 mol) was added at 60°C, and the mixture was stirred for 3 h. The mixture was washed with water, extracted with ethyl acetate, dried, filtered, and concentrated under reduced pressure to obtain a crude compound D5, which was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 12: 1 (v / v)) to obtain compound D5 (69 g, 75%).

[0189] The NMR data of compound D5 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ, 7.67 (s, 8H), 7.47 (s, 8H), 7.30 (s, 6H), 4.50 (s, 4H), 2.42 (s, 12H), 1.31 (s, 18H).

[0190] (3) Anhydrous and oxygen-free operation was performed in a glove box. Compound D5 (18.48 g, 0.02 mol) was placed in a reaction bottle, toluene (50 mL) was added and stirred to dissolve, 2.0 M methyl lithium (50 mL, 0.10 mol) was slowly added dropwise, and stirred at room temperature for 1 h. ZrCl4 (13.98 g, 0.06 mol) was added and reacted for 3 h. After the reaction was completed, the mixture was filtered, the filtrate was drained, and n-hexane was added for washing. The solid product was filtered and recorded as metal complex E5.

[0191]

[0192] Example 6 Preparation of Metal Complex E6

[0193] The ligand and metal complex E6 were prepared according to the following general route:

[0194]

[0195] (1) Compound C (48.8 g, 0.1 mol), B1 (13.6 g, 0.1 mol), and B2 (14.2 g, 0.1 mol) were added to acetonitrile, and triethylamine (40.2 g, 0.4 mol) was added after stirring to dissolve. HATU (11.4 g, 0.03 mol) was added at 60°C, and the mixture was stirred for 3 h. The mixture was washed with clean water, extracted with ethyl acetate, dried, filtered, and concentrated under reduced pressure to obtain a crude compound D6, which was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 12: 1 (v / v)) to obtain compound D6 (54 g, 73%).

[0196] The NMR data of compound D6 are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ 8.12 (s, 5H), 7.98 (s, 4H), 4.05 (s, 4H), 2.42 (s, 12H), 1.31 (s, 18H), 1.28 (s, 8H), 1.26 (s, 2H).

[0197] (3) Anhydrous and oxygen-free operation was performed in a glove box. Compound D6 (38.95 g, 0.05 mol) was placed in a reaction bottle, benzene (80 mL) was added and stirred to dissolve, and metallic sodium (4.6 g, 0.2 mol) was slowly added. The temperature was set to 55°C, and ZrCl4 (13.98 g, 0.06 mol) was added. The reaction was allowed to react for 2 h. After the reaction was completed, the mixture was filtered, the filtrate was drained, and n-hexane was added for washing. The solid product was filtered and recorded as metal complex E6.

[0198]

[0199] Example 7 Preparation of Metal Complex E7

[0200]

[0201] (1) Dissolve hydrazine hydrate (75 g, 1.5 mol) and compound A6 (102 g, 1 mol) in methanol (500 mL) and turn on the magnetic stirring to allow the reactants to completely dissolve in the solvent. Set the temperature to 80 °C and react for 5 h. After the reaction is completed, cool and solid will precipitate. After standing overnight, filter and dry to obtain compound B6 (89 g, 87%).

[0202] The NMR data of compound B6 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ, 7.07 (s, 1H), 3.71 (s, 2H), 2.31 (s, 2H), 1.27 (s, 2H), 0.98 (s, 3H).

[0203] (2) Compound C (48.8 g, 0.1 mol) and B6 (30 g, 0.3 mol) were added to DMSO, and triethylamine (60.2 g, 0.6 mol) was added after stirring to dissolve. HATU (19 g, 0.05 mol) was added at 40°C, and the mixture was stirred for 3 h. The mixture was washed with water, extracted with ethyl acetate, dried, filtered, and concentrated under reduced pressure to obtain a crude compound D7, which was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 12: 1 (v / v)) to obtain compound D7 (55 g, 84%).

[0204] The NMR data of compound D7 are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ 8.12 (s, 4H), 4.05 (s, 4H), 2.31 (s, 4H), 1.27 (s, 4H), 1.31 (s, 18H), 0.98 (s, 6H).

[0205] (3) Anhydrous and oxygen-free operation was performed in a glove box. Compound D7 (17 g, 0.026 mol) was placed in a reaction bottle, benzene (100 mL) was added and stirred to dissolve, 1.6 M n-hexyllithium (89.37 mL, 0.143 mol) was slowly added dropwise, the temperature was set to 50°C, ZrCl4 (18.51 g, 0.078 mol) was added, and the reaction was carried out for 1 h. After the reaction was completed, the filtrate was filtered, the filtrate was drained, n-hexane was added for washing, and the solid product was obtained by filtration, which was recorded as metal complex E7.

[0206]

[0207] Comparative Example 1 Preparation of Metal Complex D1

[0208] The method of Example 1 of patent CN1408731A was used to prepare catalyst D1 shown in the following formula.

[0209]

[0210] Comparative Example 2 Preparation of Metal Complex D2

[0211] The method of Example 2 of patent CN116284510A was used to prepare catalyst D2 shown in the following formula.

[0212]

[0213] Comparative Example 3 Preparation of Metal Complex D3

[0214] The method of Example 3 of patent CN 117430733 A was used to prepare catalyst D3 shown in the following formula.

[0215]

[0216] Comparative Example 4 Preparation of Metal Complex D4

[0217] The method of Example 6 of patent CN 117430733 A was used to prepare catalyst D4 shown in the following formula.

[0218]

[0219] Preparation Example Preparation of polyolefin

[0220] The metal complexes prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were used as main catalysts, and ethylene / 1-hexene copolymerization was carried out according to the following method and the raw materials, parameters, etc. shown in Table 1 to prepare the corresponding polyolefin products:

[0221] The autoclave containing the main catalyst (1 μmol) was set at 150°C, dried for 3 hours, vacuumed and gradually cooled to 25°C. 350ml Isopar E, 100mL 1-hexene, tert-butylaluminoxane, and tris-pentafluorophenyl borate were added in sequence, wherein the molar ratio of the metal element of tert-butylaluminoxane to the main catalyst was recorded as Al / M, the molar ratio of the B element in tris-pentafluorophenyl borate to the metal element M in the main catalyst was recorded as B / M, and the addition amounts of tert-butylaluminoxane and tris-pentafluorophenyl borate were shown in Table 1. The temperature was raised to 80°C to 250°C, 1MPa to 8MPa of ethylene monomer was introduced, the ampoule was broken, and the polymerization reaction was carried out. During the entire polymerization, the stirring rate, polymerization temperature and ethylene pressure remained unchanged, the reaction time was 5 minutes, and the temperature and pressure were shown in Table 1. After the reaction, the gas in the autoclave was emptied, the reaction liquid was neutralized, the polymer precipitate was obtained, washed several times, and dried to obtain a polyolefin product.

[0222] Table 1 Reaction conditions of each embodiment and comparative example

[0223]

[0224] Test Example Performance Test of Polyolefin

[0225] (1) The copolymerization activity of the polymer is calculated according to the following formula:

[0226] Copolymerization activity = polymer mass / (metal content in catalyst*polymerization time);

[0227] (2) The weight average molecular weight (Mw) of the polymer was measured by PL-GPC220 at 160°C, using three PLgel 10 μm MIXED-B separation columns connected in series and 1,2,4-trichlorobenzene as the solvent;

[0228] (3) The polymer dispersibility index (PDI) was calculated by NMR;

[0229] (4) The glass transition temperature Tg of the polymer was measured by DSC method;

[0230] (5) [mmmm] represents the isomorphism of the polymer, which is formed by high temperature 13 C NMR measured, high temperature 13 C NMR was measured at 120°C using 1,1,2,2-tetrachloroethane as solvent using Brucker DMX 100 MHz.

[0231] (6) The calculation method of the comonomer (1-hexene) insertion rate is based on the reference (Macromolecules 1999, 32, 3817);

[0232] (7) The content of double bonds at the polymer terminals was calculated using the iodine titration method.

[0233] The polyolefin products prepared in each embodiment and comparative example were subjected to the performance tests shown in Table 2 below, and the results are as follows:

[0234] Table 2 Performance test results

[0235]

[0236] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0237] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the patent application. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A bimetallic compound based on a hydrazide pyrene skeleton having the structural characteristics shown in the following formula (I): in, R 1 , R 2 Each independently includes C1-C24 alkyl, C6-C30 aryl, C3-C18 cycloalkyl, C5-C10 cycloalkenyl or C6-C30 aryl substituted with C1-C5 alkoxy; Each occurrence of M independently comprises a Group IVB metal element; Each occurrence of X independently includes halogen, C1-C16 alkyl or -C1-C5 alkyl-C6-C16 aryl.

2. The bimetallic compound based on hydrazide pyrene skeleton according to claim 1, It is characterized in that R 1 , R 2 Each independently includes C1-C10 alkyl, C6-C16 aryl, C3-C8 cycloalkyl, C5-C8 cycloalkenyl or C6-C16 aryl substituted by C1-C3 alkoxy; Optionally, R 1 , R 2 Each independently includes C1-C6 alkyl, C6-C14 aryl, C3-C6 cycloalkyl, C5-C8 cycloalkenyl or C1-C3 alkoxy substituted C6-C14 aryl; Further optionally, R 1 , R 2 Each independently includes phenyl, p-methylphenyl, p-methoxyphenyl, cyclopropyl, cyclohexyl, cyclooctyl, cyclopentadienyl or anthracenyl.

3. The bimetallic compound based on hydrazide pyrene skeleton according to claim 1, It is characterized in that Has one of the following structural features:

4. The bimetallic compound based on hydrazide pyrene skeleton according to any one of claims 1 to 3, It is characterized in that Each occurrence of M independently comprises titanium, zirconium or hafnium.

5. The bimetallic compound based on hydrazide pyrene skeleton according to any one of claims 1 to 3, It is characterized in that X, when it occurs each time, independently includes halogen, C1-C10 alkyl or -C1-C3 alkyl-C6-C10 aryl; Optionally, each occurrence of X independently comprises halogen, C1-C8 alkyl or -C1-C3 alkyl-C6-C8 aryl; Further optionally, each occurrence of X independently includes halogen, C1-C6 alkyl or -C1-C2 alkyl-C6-C8 aryl; In a further alternative, each X independently comprises methyl, chloro or benzyl.

6. The method for preparing the bimetallic compound based on hydrazide pyrene skeleton according to any one of claims 1 to 5, It is characterized in that The steps include: In the presence of a hydrogen extraction agent, the ligand compound represented by formula (II) is reacted with a metal salt MX 4 Carry out complexation reaction; 7. The method for preparing the bimetallic compound based on hydrazide pyrene skeleton according to claim 6, It is characterized in that Has one or more of the following characteristics: (1) Metal salt MX 4 Including titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride, tetrabenzylhafnium, tetra(ethylmethyl)zirconium amino, titanium tetrabromide, zirconium tetrabromide or hafnium tetrabromide; (2) The molar ratio of the ligand compound represented by formula (II) to the metal salt MX4 is 1:(2-5); (3) The molar ratio of the ligand compound represented by formula (II) to the hydrogen extraction agent is 1:(4-8); (4) The hydrogen extraction reagent includes one or more of alkyl lithium, phenyl lithium, sodium hydride, elemental sodium and Grignard reagent; (5) The conditions of the complexation reaction include: temperature of 20°C to 60°C and time of 1 h to 4 h.

8. The method for preparing the bimetallic compound based on hydrazide pyrene skeleton according to claim 6 or 7, It is characterized in that The preparation method of the ligand compound represented by formula (II) comprises the following steps: Compound A is selected from R 1 -COOCH 3 or R 2 -COOCH 3 ; Compound B is selected from Compound C is selected from Performing a first reaction between hydrazine hydrate and compound A to prepare compound B; In the presence of a catalyst and a base, compound C and compound B are subjected to a second reaction to prepare a ligand compound represented by formula (II); Optionally, the conditions of the first reaction include: temperature of 30°C to 80°C, time of 1h to 12h; Optionally, compound A includes one or more of methyl benzoate, methyl n-butyrate, methyl cyclohexylcarboxylate, methyl cyclopropylcarboxylate, methyl 4-methylbenzoate, methyl 4-methoxycarboxylate, methyl 3,4,5-trimethylcarboxylate, methyl 3,4,5-trimethoxycarboxylate, methyl 3,4,5-trichlorocarboxylate, methyl 4-methylcyclohexylcarboxylate, methyl 3,4,5-trimethylcyclohexylcarboxylate, methyl 3,4,5-trimethoxycyclohexylcarboxylate, methyl tetrahydrothiopyran-4-carboxylate, methyl 9-carboxylate anthracene and methyl cyclooctylcarboxylate; Optionally, the molar ratio of compound A to hydrazine in hydrazine hydrate is 1:(1 to 1.5); Optionally, the conditions of the second reaction include: temperature of 25°C to 60°C, time of 2h to 5h; Optionally, the catalyst comprises 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate; Optionally, the base includes one or more of triethylamine, N,N-diisopropylethylamine and pyridine; Optionally, the molar ratio of compound C, the catalyst, the base and compound B is 1:(0.2-0.5):(2-6):(2-4).

9. Use of the bimetallic compound based on hydrazide pyrene skeleton as claimed in any one of claims 1 to 5 as a catalyst in the preparation of polyolefins.

10. A method for preparing polyolefin, It is characterized in that The steps include: In the presence of the bimetallic compound based on the hydrazide pyrene skeleton as claimed in any one of claims 1 to 5, polymerizing olefin monomers in a solvent to prepare polyolefin; Optionally, the concentration of the bimetallic compound based on hydrazide pyrene skeleton in the solvent is 0.1 ppm to 50 ppm; Optionally, the solvent further comprises a co-catalyst; further optionally, the co-catalyst comprises one or more of alkyl aluminum and borate; Optionally, the polymerization temperature is 10°C to 300°C; Optionally, the polymerization reaction pressure is 0.1Mpa to 20Mpa; Optionally, the solvent includes one or more of an alkane solvent, a cycloalkane solvent and an aromatic solvent.

Images