Biphenyl urea skeleton-based bimetallic catalyst, and preparation method and application thereof

Abstract

The invention belongs to the technical field of catalyst preparation, and particularly relates to a biphenyl urea skeleton-based bimetallic catalyst, and a preparation method and application thereof. The bimetallic catalyst has a structure as shown in a formula 1, adopts a biphenyl urea skeleton, and is connected with group urea through carbon atoms, so that the structure of the bimetallic catalyst complex is more stable, and compared with the structure of a traditional catalyst, the bimetallic catalyst obtains a better spatial configuration; the introduction of urea enables the distortion degree of bond length and bond angle to be better coordinated with metal, the pocket-shaped structure better promotes the occurrence of polymerization reaction and the insertion of chain, and meanwhile, the steric effect and power supply capability of the ligand are adjusted by changing substituent groups, so that the polymerization performance of the metal catalyst is regulated and controlled; the molecular weight, molecular weight distribution, terminal double bond content, branched chain insertion rate and other properties of the polymer can be adjusted by selecting the types and the dosages of R1-R3 and metal salts in the bimetallic catalyst, so that the polymer can be applied to different fields.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a bimetallic catalyst based on a biphenylurea framework, its preparation method, and its applications. Background Technology

[0002] Polyolefin products are one of the pillar industries of modern polymer materials industry. With the increase of α-olefin comonomer content in copolymers, the tensile strength, toughness, tear strength, and impact strength of the products are significantly improved, enabling their widespread application in films, hot melt adhesives, pipes, seals, machine tools, and many other fields. The development, innovation, and upgrading of polyolefin products are inseparable from the development of polyolefin catalysts; therefore, accelerating catalyst research is particularly crucial for the development of the polyolefin industry.

[0003] The molecular weight and copolymerization activity of polyolefins prepared by existing bimetallic catalysts need further improvement. Furthermore, existing bimetallic catalysts have poor high-temperature resistance, limiting the polymerization temperature when used to prepare polyolefins. For the art, on the one hand, polymerization is an exothermic process; if a lower polymerization temperature is required, the production equipment needs to be cooled, and industrial refrigeration is more energy-intensive than heating. On the other hand, industrial deashing requires the removal of the solvent Isopar E and octene, which is a flash evaporation process; higher temperatures are more conducive to this process. Conducting the polymerization reaction at a higher temperature helps reduce the energy consumption required for deashing. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing catalysts, such as the molecular weight and activity of polyolefins needing further improvement, and the high energy consumption of the polyolefin generation process due to the catalyst's inability to withstand high temperatures. Thus, the present invention provides a bimetallic catalyst based on a biphenylurea skeleton, its preparation method, and its applications.

[0005] To this end, the present invention provides the following technical solution.

[0006] The first aspect of this invention provides a bimetallic catalyst based on a biphenylurea framework, the structural formula of which is shown in Formula I;

[0007]

[0008] R1 is selected from hydrogen, C1-C20 alkyl, C3-C14 cycloalkyl, and any substituted or unsubstituted C6-C20 aryl;

[0009] R2 is selected from C1 to C22 alkyl groups;

[0010] R3 is selected from one of C1-C20 alkyl, C3-C14 cycloalkyl, C6-C20 aryl, C6-C20 aryloxy, and C6-C20 aromatic amino groups, whether substituted or unsubstituted.

[0011] M is selected from Group IVB metallic elements;

[0012] X is selected from halogens, C1-C20 alkyl groups, C6-C20 aryl groups, C6-C16 aralkyl groups, and C1-C20 alkylamino groups.

[0013] In one alternative embodiment, the bimetallic catalyst satisfies at least one of A to G:

[0014] A. When R1 is selected from any aryl group of C6 to C20, the substituent is a C1 to C8 alkyl or a C1 to C8 alkoxy group;

[0015] B. R1 is selected from hydrogen, methyl, ethyl, propyl, butyl, cyclopentyl, or phenyl; it is understood here that the butyl in R1 can be tert-butyl, etc.

[0016] C. R2 is selected from methyl, ethyl, propyl, isopropyl, or tert-butyl;

[0017] D. When R3 is selected from any aryl group of C6 to C20, the substituent is a C1 to C8 alkyl or a C1 to C8 alkoxy group;

[0018] E. R3 is selected from methyl, ethyl, propyl, isopropyl, butyl, cyclopentyl, phenyl, tolyl, or tert-butylphenyl; it is understood here that the butyl in R3 can be tert-butyl, etc.

[0019] F. M is selected from zirconium, titanium, or hafnium;

[0020] G. X is selected from chlorine, bromine, methyl, benzyl or dimethylamino.

[0021] In one alternative embodiment, the bimetallic catalyst represented by Formula I is selected from chemical substances represented by any of the following structural formulas:

[0022]

[0023] A second aspect of this invention provides a method for preparing a bimetallic catalyst based on a biphenylurea framework, comprising the following steps:

[0024] (1) Compound A and 5-methyl-1,3,4-thiadiazole-2-amine react under alkaline conditions to form compound B;

[0025] (2) Compound B reacts with compound C to form compound D;

[0026] (3) The compound D undergoes a complexation reaction with the metal salt MX;

[0027] Compound A has the following structural formula:

[0028]

[0029] The compound B has the following structural formula:

[0030]

[0031] Compound C is an isocyanate derivative with the following structural formula:

[0032]

[0033] The compound D has the following structural formula:

[0034]

[0035] R1 is selected from hydrogen, C1-C20 alkyl, C3-C14 cycloalkyl, and any substituted or unsubstituted C6-C20 aryl;

[0036] R2 is selected from C1 to C22 alkyl groups;

[0037] R3 is selected from one of C1-C20 alkyl, C3-C14 cycloalkyl, C6-C20 aryl, C6-C20 aryloxy, and C6-C20 aromatic amino groups, whether substituted or unsubstituted.

[0038] M is selected from Group IVB metallic elements;

[0039] X is selected from halogens, C1-C20 alkyl groups, C6-C20 aryl groups, C6-C16 aralkyl groups, and C1-C20 alkylamino groups.

[0040] In one optional embodiment, the preparation method satisfies at least one of A to G:

[0041] A. In step (1), the reaction temperature is 10-60℃ and the time is 1-5h;

[0042] B. In step (1), an alkaline substance is used to provide the alkaline conditions; the alkaline substance includes at least one of triethylamine, sodium hydroxide, potassium hydroxide, sodium carbonate and pyridine;

[0043] C. In step (1), the molar ratio of compound A and 5-methyl-1,3,4-thiadiazole-2-amine is 1:(2-4);

[0044] D. In step (1), the molar ratio of compound A to the alkaline substance is 1:(2-5);

[0045] E. In step (2), the reaction temperature is 30-120°C and the time is 2-8 hours.

[0046] F. In step (2), the reaction is carried out under a protective atmosphere;

[0047] G. In step (2), the molar ratio of compound B to compound C is 1:(2 to 2.8).

[0048] In one alternative implementation, step (3) satisfies at least one of A to E:

[0049] A. The reaction temperature is 40℃~80℃, and the time is 1h~5h;

[0050] B. The metal salt MX is selected from zirconium tetrachloride, titanium tetrachloride, hafnium tetrachloride, tetrabenzyl hafnium, tetra(dimethylamino)zirconium, titanium tetrabromide, zirconium tetrabromide or hafnium tetrabromide;

[0051] C. The molar ratio of the compound D to the metal salt MX is 1:(2-4);

[0052] D. Step (3) further includes the step of adding a dehydrogenating agent;

[0053] The dehydrogenation reagent is at least one of alkyllithium, phenyllithium, potassium carbonate, sodium carbonate, potassium carbonate, and sodium hydride.

[0054] Preferably, the dehydrogenating agent is at least one selected from n-butyllithium, methyllithium, and n-hexyllithium;

[0055] E. The molar ratio of compound D to the dehydrogenating agent is 1:(4-7).

[0056] In an optional embodiment, in step (1), compound A and 5-methyl-1,3,4-thiadiazole-2-amine are first mixed in a solvent, and then an alkaline substance is added; wherein, the solvent may be one or more of ethanol, methanol, acetonitrile, benzene, toluene, tetrahydrofuran, 1,4-dioxane, DMF, and acetone, and the amount used is 5 to 20 times the mass of compound A.

[0057] In an alternative implementation, step (2) provides an inert atmosphere using nitrogen or argon.

[0058] In an optional embodiment, in step (2), after mixing compound B and compound C, a solvent is added. The solvent may be one or more of DCM, DMF, tetrahydrofuran, acetonitrile, tetrahydrofuran, and chloroform, and the amount used is 5 to 20 times the mass of compound B.

[0059] In an optional embodiment, step (3) further includes adding a solvent, which may be one or more of tetrahydrofuran, acetonitrile, toluene, n-hexane, diethyl ether, and butyl ether, and the amount of solvent used is 1 to 10 times the mass of compound D; step (3) is carried out in a glove box.

[0060] A third aspect of the present invention provides a catalyst for preparing polyolefins, comprising the above-described bimetallic catalyst or the bimetallic catalyst prepared by the above-described preparation method.

[0061] In an optional embodiment, the catalyst further includes a co-catalyst, which is at least one of alkylaluminum and borate; the co-catalyst satisfies at least one of A to D:

[0062] A. The alkylaluminum is selected from C1 to C10 alkylaluminoxanes or alkyl-modified aluminumoxanes;

[0063] Preferably, the alkylaluminum is methylaluminoxane, ethylaluminoxane, or tert-butylaluminoxane;

[0064] B. The borate is selected from at least one or more of N,N-dimethylphenylamine tetra(pentafluorophenyl)borate, tripentafluorophenyl borate, and triphenylmethyltetra(pentafluorophenyl) borate;

[0065] Preferably, the borate is trifluorophenyl borate;

[0066] C. Based on the metal element Al in the alkylaluminum and the metal element M in the bimetallic catalyst, the molar ratio of the alkylaluminum to the bimetallic catalyst is (5-400):1.

[0067] D. Based on element B in the borate and metal element M in the bimetallic catalyst, the molar ratio of the borate to the bimetallic catalyst is (0-25):1.

[0068] A fourth aspect of the present invention provides a method for preparing a polyolefin, comprising: polymerizing an olefin under the action of the above-mentioned catalyst.

[0069] In one optional embodiment, the preparation method satisfies at least one of A to B:

[0070] A. The olefin is selected from at least one of ethylene, propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, styrene, and norbornene;

[0071] B. The polymerization reaction is carried out at a temperature of 50–300°C and a pressure of 0.1–20 MPa.

[0072] Preferably, the polymerization reaction is carried out at a temperature of 80–250°C and a pressure of 1–8 MPa.

[0073] In one optional embodiment, the polymerization reaction further includes the step of adding a solvent, which may be at least one of alkanes, cycloalkanes and aromatics, preferably Isopar E, toluene, n-heptane and cyclohexane.

[0074] The polymerization reaction is particularly suitable for the polymerization of ethylene and α-olefins.

[0075] The technical solution of this invention has the following advantages:

[0076] 1. The present invention provides a bimetallic catalyst based on a biphenylurea skeleton, which has the structure shown in Formula 1. The biphenylurea skeleton is connected to the urea group via carbon atoms, making the structure of the bimetallic catalyst complex more stable. Compared with the structure of traditional catalysts, the present invention achieves a better spatial configuration. The introduction of urea allows for better coordination with the metal by adjusting the bond length and bond angle distortion. The pocket-like structure better promotes the polymerization reaction and chain insertion. Simultaneously, the steric hindrance effect and power supply capability of the ligands can be adjusted by changing the substituents, thereby achieving the regulation of the polymerization performance of the metal catalyst. By selecting the types and amounts of R1-R3 and metal salts in the bimetallic catalyst, the molecular weight, molecular weight distribution, terminal double bond content, and branching rate of the polymer can be adjusted, thus enabling the polymer to be applied to different fields.

[0077] When the bimetallic catalyst of this invention is used to catalyze olefin polymerization, it will not fail under high-temperature polymerization conditions, the olefin polymerization process has low energy consumption, the obtained polyolefins have ultra-high molecular weight and narrow molecular weight distribution, high copolymerization activity, low content of terminal double bonds, and high polyolefin yield, and has broad application prospects. Detailed Implementation

[0078] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0079] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0080] The main sources of the main materials and reagents used in the following examples are as follows:

[0081] Compound A can be commercially available or prepared according to methods in existing literature; for example, compound A was prepared according to Eur. J. Med. Chem (2020), 205, 112581 (title: Discovery of novel quinazolinone derivatives as potential anti-HBV and anti HCC aggents), and the general formula for the preparation of compound A is as follows:

[0082]

[0083] Taking compound 3,3′-bis(chloromethyl)-5,5′-bis(1,1-dimethylethyl)-2,2′-dimethoxy-1,1′-biphenyl as an example:

[0084]

[0085] 37% HCl (33 mL, 0.4 mol) was added to a mixture of 5,5′-bis(1,1-dimethylethyl)-2,2′-dimethoxy-1,1′-biphenyl (32.6 g, 0.1 mol) and paraformaldehyde (32.43 g, 0.36 mol). The mixture was stirred at 90 °C for 8 h. After the reaction was complete, the mixture was cooled to room temperature. The mixture was extracted with ethyl acetate and washed with water, 5% hydrochloric acid, and saturated NaHCO3 solution. Excess water was dried over anhydrous Na2SO4, and the solvent was removed by evaporation under reduced pressure. The mixture was purified by silica gel column chromatography (petroleum ether:ethyl acetate = 10:1 (v / v)) to give compound 3,3′-bis(chloromethyl)-5,5′-bis(1,1-dimethylethyl)-2,2′-dimethoxy-1,1′-biphenyl (27.52 g, 65%).

[0086] The NMR data for 3,3′-bis(chloromethyl)-5,5′-bis(1,1-dimethylethyl)-2,2′-dimethoxy-1,1′-biphenyl are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ7.90 (d, J = 3.1Hz, 2H), 7.19 (d, J = 2.9Hz, 2H), 5.08 (s, 4H), 3.92 (s, 6H), 1.32 (s, 18H).

[0087] Compound C can be commercially available or prepared according to existing literature methods; for example, compound C was prepared according to J. Antibiot (2016), 69(11), 811-817, and the general formula for the preparation of compound C is as follows:

[0088]

[0089] Take phenyl isocyanate as an example:

[0090]

[0091] Propylene carbonate (16.3 g, 0.55 mol) was dissolved in CHCl3 (60 ml), and a CHCl3 solution of aniline (9.3 g, 0.1 mol) was added dropwise. The mixture was placed in an ice bath and stirred for 10 min. It was then removed from the ice bath and stirred at room temperature for 1 h. The mixture was heated to 60 °C until the reaction solution became clear. The reaction was then evaporated to give phenyl isocyanate.

[0092] The NMR data of phenyl isocyanate are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ 7.34 (t, J = 7.5Hz, 2H), 7.14-7.09 (m, 1H), 7.03 (dd, J = 7.5, 1.4Hz, 2H).

[0093] Aniline: AR, Innochem; Benzene: AR, Aladdin; Toluene: AR, Aladdin; Tetrahydrofuran: AR, Innochem; DMF: AR, Innochem; DCM: AR, Innochem; Ethyl acetate: AR, Aldrich; Petroleum ether: AR, Aldrich; Anhydrous sodium sulfate: AR, Innochem; Silica gel: AR, Aladdin; Hydrochloric acid: AR, Aldrich; Methyllithium: AR, Innochem; n-Butyllithium: AR, Innochem; Triethylamine: AR, Innochem; Sodium hydroxide: AR, Innochem; Sodium carbonate: AR, Innochem; TiCl4: Tokyo Chemical Industry Co., Ltd.; ZrCl4: Tokyo Chemical Industry Co., Ltd.; HfCl4: Tokyo Chemical Industry Co., Ltd.; ZrBn4: Tokyo Chemical Industry Co., Ltd.; Tris(pentafluorophenyl)boron: AR, Aladdin; Phenoxyimide zirconium: AR, Aladdin; Isopar E: ExxonMobil Corporation; tert-butylaluminoxane (MAO): Albemarle; Ethylene: 99.9%, Beijing Yanshan Petrochemical Company; 1-hexene: 98%, Beijing Yanshan Petrochemical Company.

[0094] Unless otherwise specified, all other raw materials and reagents were purchased through commercial channels.

[0095] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. In all the examples and comparative examples below, the chemical reactions involved were carried out after nitrogen purging.

[0096] The bimetallic catalysts in the following examples were synthesized according to the following synthetic route:

[0097]

[0098] Example 1

[0099] This embodiment provides a bimetallic catalyst E1 based on a biphenylurea framework, with the following structural formula:

[0100]

[0101] The preparation method, synthetic route, and steps of the above-mentioned bimetallic catalyst are as follows:

[0102]

[0103] (1) Compound A1 (31 g, 0.1 mol) and 5-methyl-1,3,4-thiadiazole-2-amine (23.03 g, 0.2 mol) were placed in a flask, and triethylamine (20.24 g, 0.2 mol) and ethanol (350 mL) were added to dissolve them. The mixture was stirred and the temperature was set to 25 °C. The reaction was monitored by TLC. The reaction was stopped after 1 h. The reaction solution was concentrated, and the crude product was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound B1. The crude compound B1 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 20:1 (v / v)) to obtain compound B1 (21.79 g, 80%).

[0104] The NMR data of compound B1 are as follows: ¹H NMR (CDCl3, 500MHz, TMS) δ 7.95 (dd, J = 14.8, 3.1Hz, 2H), 7.38 (dd, J = 15.0, 3.1Hz, 2H), 7.21 (t, J = 14.9Hz, 2H), 4.46 (s, 4H), 3.92 (s, 6H), 1.42 (s, 4H).

[0105] (2) Compound B1 (27.2 g, 0.1 mol) and compound C1 (11.41 g, 0.2 mol) were added to a three-necked flask, and dry dichloromethane (DCM) (300 mL) was added. The mixture was stirred until completely dissolved. Nitrogen gas was introduced into the reaction system and the temperature was set to 35 °C. The extent of the reaction was monitored by TLC. The reaction was stopped after 7 h. The reaction solution was concentrated, and the crude product was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound D1. The crude product was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10:1 (v / v)) to obtain compound D1 (28.98 g, 75%).

[0106] The NMR data for compound D1 are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ7.96 (dd, J=14.8, 3.1Hz, 2H), 7.38 (dd, J=15.0, 3.1Hz, 2H), 7 .22(t,J=14.9Hz,2H),6.13(s,2H),4.77(s,2H),4.20(s,4H),3.92(s,6H),2.71(s,6H).

[0107] (3) Anhydrous and oxygen-free operation was carried out in a glove box. Compound D1 (10g, 0.026mol) was placed in a reaction flask, toluene (30mL) was added and stirred to dissolve. 1.6M methyllithium (65mL, 0.104mol) was slowly added dropwise. The mixture was stirred at room temperature for 10min. Zirconium tetrachloride (12.12g, 0.052mol) was added. The temperature was set at 40℃ and the reaction was carried out for 1h. After the reaction was completed, the mixture was filtered, the filtrate was dried under vacuum, and hexane was added to wash the product. The solid product was obtained by filtration and was recorded as metal complex E1 (9.75g, 60%).

[0108] The NMR data for compound E1 are as follows: 1 H NMR (CDCl3, 500MHz, TMS) δ 8.13 (dd, J = 14.8, 3.1 Hz, 2H), 7.38 (dd, J = 15.0, 3.1 Hz, 2H), 7.18 (t, J = 14.9 Hz, 2H), 4.01 (s, 4H), 3.92 (s, 6H), 2.00 (s, 6H).

[0109] Example 2

[0110] This embodiment provides a bimetallic catalyst E2 based on a biphenylurea framework, with the following structural formula:

[0111]

[0112] The preparation method, synthetic route, and steps of the above-mentioned bimetallic catalyst are as follows:

[0113]

[0114] (1) Compound A2 (36.7 g, 0.1 mol) and 5-methyl-1,3,4-thiadiazol-2-amine (34.55 g, 0.3 mol) were placed in a flask, sodium hydroxide (8 g, 0.2 mol) was added, and acetonitrile (400 mL) was added to dissolve the compound. The mixture was stirred and the temperature was set at 40 °C. The reaction was monitored by TLC. The reaction was stopped after 3 h. The reaction solution was concentrated, and the crude product was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound B2. The crude compound B2 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 30:1 (v / v)) to obtain compound B2 (25.29 g, 77%).

[0115] The NMR data of compound B2 are as follows: ¹H NMR (CDCl₃, 500MHz, TMS) δ 7.75 (d, J = 2.9Hz, 2H), 7.18 (d, J = 3.1Hz, 2H), 4.46 (s, 4H), 4.07 (q, J = 11.8Hz, 4H), 2.31 (s, 6H), 1.52 (s, 4H), 1.34 (t, J = 11.8Hz, 6H).

[0116] (2) Compound B2 (32.85 g, 0.1 mol) and compound C2 (27.40 g, 0.23 mol) were added to a two-necked flask, and dry tetrahydrofuran (350 mL) was added. The mixture was stirred until the solid was completely dissolved. Nitrogen gas was introduced into the reaction system and the nitrogen atmosphere was maintained. The temperature was set to 50 °C. The reaction was monitored by TLC. The reaction was stopped after 5 h. The reaction solution was concentrated, and the crude product was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound D2. The crude product was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 5:1 (v / v)) to obtain compound D2 (35.70 g, 63%).

[0117] The NMR data of compound D2 are as follows: ¹H NMR (CDCl3, 500MHz, TMS) δ 8.11 (s, 2H), 7.74 (d, J = 2.9Hz, 2H), 7.35–7.15 (m, 10H), 6.96–6.77 (m, 2H), 6.65 (s, 2H), 4.19 (s, 4H), 4.06 (q, J = 11.8Hz, 4H), 2.31 (s, 6H), 1.34 (t, J = 11.8Hz, 6H).

[0118] (3) Anhydrous and oxygen-free operation was carried out in a glove box. Compound D2 (15g, 0.026mol) was placed in a reaction flask, acetonitrile (70mL) was added and stirred to dissolve. 2.5M butyllithium (52mL, 0.13mol) was slowly added dropwise. The mixture was stirred at room temperature for 15min. Hafnium tetrachloride (24.98g, 0.078mol) was added. The temperature was set at 60℃ and the reaction was carried out for 2h. After the reaction was completed, the mixture was filtered, the filtrate was dried under vacuum, and hexane was added for washing. The solid product was obtained by filtration and recorded as metal complex E2 (14.63g, 53%).

[0119] The NMR data of compound E2 are as follows: ¹H NMR (CDCl3, 500MHz, TMS) δ 7.74 (d, J = 2.9Hz, 2H), 7.35–7.15 (m, 10H), 6.96–6.77 (m, 2H), 4.53 (s, 4H), 4.06 (q, J = 11.8Hz, 4H), 1.95 (s, 6H), 1.11 (t, J = 11.8Hz, 6H).

[0120] Example 3

[0121] This embodiment provides a bimetallic catalyst E3 based on a biphenylurea framework, with the following structural formula:

[0122]

[0123] The preparation method, synthetic route, and steps of the above-mentioned bimetallic catalyst are as follows:

[0124]

[0125] (1) Compound A3 (47.95 g, 0.1 mol) and 5-methyl-1,3,4-thiadiazole-2-amine (46.06 g, 0.4 mol) were placed in a flask, dissolved in toluene (250 mL), stirred, and sodium carbonate (53 g, 0.5 mol) was added to create an alkaline environment. The stirring continued, and the temperature was set to 60 °C. The reaction was judged by TLC. After 3 h of reaction, the starting material spot A3 disappeared, and the reaction ended. The reaction solution was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound B3. The crude compound B3 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 15:1 (v / v)) to obtain compound B3 (36.13 g, 82%).

[0126] The NMR data of compound B3 are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ 7.90 (d, J = 3.1Hz, 2H), 7.19 (d, J = 2.9Hz, 2H), 4.69 (hept, J = 11.3Hz, 2H), 4.51 (s, 4H), 1.56 (s, 4H), 1.31 (d, J = 10.8Hz, 30H).

[0127] (2) Compound B3 (44.01 g, 0.1 mol) and compound C3 (37.28 g, 0.28 mol) were added to a two-necked flask, and 700 mL of dry DMF solution was added. The mixture was stirred until the solid was completely dissolved. Argon gas was introduced into the reaction system and an argon atmosphere was maintained. The temperature was set to 120 °C. The reaction was monitored by TLC. After 4 h, the reaction was considered complete when the starting material B3 spot disappeared. The reaction solution was washed with a large amount of distilled water, extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound D3. The crude compound D3 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 25:1 (v / v)) to obtain compound D3 (41.71 g, 59%).

[0128] The NMR data of compound D3 are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ 8.00 (s, 2H), 7.90 (s, 2H), 7.21 (d, J = 15.0Hz, 6H), 6.96 (s, 4H), 6.54 (s, 2H), 4.69 (s, 2H), 4.20 (s, 4H), 2.32 (s, 6H), 1.32 (d, J = 5.0Hz, 30H).

[0129] (3) Anhydrous and oxygen-free operation was carried out in a glove box. Compound D3 (20g, 0.028mol) was placed in a flask, and ether (300mL) was added and stirred to dissolve. 2.0M n-butyllithium (95mL, 0.19mol) was slowly added and stirred at room temperature for 10min. Titanium tetrabromide (41.16g, 0.112mol) was added. The temperature was set at 80℃ and the reaction was carried out for 5h. After the reaction was completed, the mixture was filtered, the filtrate was dried, and hexane was added to wash the mixture. The solid product was obtained by filtration and recorded as metal complex E3 (20.98g, 67%).

[0130] The NMR data of compound E3 are as follows: 1H NMR (CDCl3, 500MHz, TMS) δ 7.90 (s, 2H), 7.21 (d, J = 15.0 Hz, 6H), 6.84 (s, 4H), 4.52 (s, 2H), 4.01 (s, 4H), 2.18 (s, 6H), 1.32 (d, J = 5.0 Hz, 30H).

[0131] Example 4

[0132] This embodiment provides a bimetallic catalyst E4 based on a biphenylurea framework, with the following structural formula:

[0133]

[0134] The preparation method, synthetic route, and steps of the above-mentioned bimetallic catalyst are as follows:

[0135]

[0136] (1) Compound A4 (44.74 g, 0.1 mol) and 5-methyl-1,3,4-thiadiazol-2-amine (28.79 g, 0.25 mol) were placed in a flask, dissolved in tetrahydrofuran (400 mL), and stirred. Triethylamine (30.36 g, 0.3 mol) was then added, and stirring continued until the reaction solution was alkaline. The oil bath temperature was set to 30 °C. The reaction was assessed by TLC. After 4 h, the starting material A4 spot disappeared, indicating the end of the reaction. The reaction solution was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound B4. The crude compound B4 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 14:1 (v / v)) to obtain compound B4 (28.19 g, 69%).

[0137] The NMR data of compound B4 are as follows: ¹H NMR (CDCl₃, 500MHz, TMS) δ 7.91 (d, J = 2.9Hz, 2H), 7.20 (d, J = 2.9Hz, 2H), 4.38 (s, 4H), 3.92 (s, 6H), 3.90–2.12 (m, 2H), 2.12–1.48 (m, 16H), 1.46 (s, 4H).

[0138] (2) Compound B4 (40.86 g, 0.1 mol) and compound C4 (27.79 g, 0.25 mol) were added to a reaction flask, along with 500 mL of tetrahydrofuran. The mixture was stirred until the solid was completely dissolved. Argon gas was introduced into the reaction system and maintained under an argon atmosphere. The temperature was set to 90 °C. The reaction was monitored by TLC. After 6 hours, the starting material B4 spot disappeared, indicating the end of the reaction. The reaction solution was concentrated under reduced pressure to remove the tetrahydrofuran. The solution was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound D4. The crude compound D4 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 10:1 (v / v)) to obtain compound D4 (33.44 g, 53%).

[0139] The NMR data of compound D4 are as follows: ¹H NMR (CDCl₃, 500MHz, TMS) δ 7.91 (d, J = 2.9Hz, 2H), 7.20 (d, J = 2.9Hz, 2H), 6.09 (s, 2H), 4.58–4.45 (m, 2H), 4.45 (d, J = 15.5Hz, 2H), 4.20 (s, 4H), 3.92 (s, 6H), 3.02–2.52 (m, 2H), 2.22–1.34 (m, 32H).

[0140] (3) Anhydrous and oxygen-free operation was carried out in a glove box. Compound D4 (30g, 0.048mol) was placed in a flask, and tetrahydrofuran solution (50mL) was added and stirred to dissolve. 2.5M methyllithium (96mL, 0.24mol) was slowly added and stirred at room temperature for 10min. Tetrabenzylhafnium (65.16g, 0.12mol) was added and the temperature was set at 75℃. The reaction was carried out for 3h. After the reaction was completed, the mixture was filtered, the filtrate was dried, and hexane was added for washing. The solid product was obtained by filtration and recorded as metal complex E4 (45.30g, 70%).

[0141] The NMR data of compound E4 are as follows: ¹H NMR (CDCl₃, 500MHz, TMS) δ 7.91 (d, J = 2.9Hz, 2H), 7.35 (d, J = 15Hz, 20H), 7.18 (d, J = 2.9Hz, 2H), 4.51–4.35 (m, 2H), 4.12 (s, 4H), 3.92 (s, 6H), 3.02–2.38 (m, 2H), 2.20 (m, 4H), 2.13–1.34 (m, 32H), 1.13 (m, 4H).

[0142] Example 5

[0143] This embodiment provides a bimetallic catalyst E5 based on a biphenylurea framework, with the following structural formula:

[0144]

[0145] The preparation method, synthetic route, and steps of the above-mentioned bimetallic catalyst are as follows:

[0146]

[0147] (1) Compound A5 (42.34 g, 0.1 mol) and 5-methyl-1,3,4-thiadiazole-2-amine (34.55 g, 0.3 mol) were placed in a flask, and triethylamine (40.48 g, 0.4 mol) was added. Benzene (600 mL) was added to dissolve the compound. The mixture was stirred and the reaction was monitored by TLC at room temperature and pressure. The reaction was stopped after 1 h. The reaction solution was concentrated, and the crude product was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound B5. The crude compound B5 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 38:1 (v / v)) to obtain compound B5 (29.61 g, 77%).

[0148] The NMR data for compound B5 are as follows: 1H NMR (CDCl) 3,500MHz, TMS) δ7.79(d,J=2.9Hz,2H),7.08(d,J=3.1Hz,2H),4.42(s,4H),3.92(s,6H), 2.64(t,J=15.3Hz,4H),1.64–1.49(m,8H),1.42–1.25(m,4H),0.89(t,J=13.0Hz,6H).

[0149] (2) Compound B5 (38.45 g, 0.1 mol) and compound C5 (24.78 g, 0.25 mol) were added to a three-necked flask, and dry acetonitrile (600 mL) was added. The mixture was stirred until completely dissolved. Nitrogen gas was introduced into the reaction system and the temperature was set to 35 °C. The extent of the reaction was monitored by TLC. The reaction was stopped after 8 h. The reaction solution was concentrated, and the crude product was extracted with ethyl acetate, washed, dried, filtered, and concentrated under reduced pressure to obtain crude compound D5. The crude product was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 15:1 (v / v)) to obtain compound D5 (32.06 g, 55%).

[0150] The NMR data of compound D5 are as follows: ¹H NMR (CDCl₃, 500MHz, TMS) δ 7.79 (d, J = 2.9Hz, 2H), 7.08 (d, J = 3.1Hz, 2H), 6.30 (s, 2H), 4.88 (s, 2H), 4.20 (s, 4H), 3.92 (s, 6H), 2.85–2.72 (m, 4H), 2.70–2.57 (m, 4H), 1.68–1.45 (m, 4H), 1.43–1.21 (m, 12H), 1.01–0.77 (m, 12H).

[0151] (3) Anhydrous and oxygen-free operation was carried out in a glove box. Compound D5 (20g, 0.034mol) was placed in a reaction flask, toluene (40mL) was added and stirred to dissolve. 2.5M n-butyllithium (80mL, 0.20mol) was slowly added dropwise and stirred at room temperature for 15min. Zirconium tetrachloride (19.81g, 0.085mol) was added and the temperature was set at 80℃. The reaction was carried out for 3h. After the reaction was completed, the mixture was filtered, the filtrate was dried under vacuum, and hexane was added to wash the mixture. The solid product was obtained by filtration and was recorded as metal complex E5 (20.26g, 66%).

[0152] The NMR data for compound E5 are as follows: ¹H NMR (CDCl₃, 500MHz, TMS) δ 7.79 (d, J = 2.9Hz, 2H), 7.188 (d, J = 3.1Hz, 2H), 4.04 (s, 4H), 3.92 (s, 6H), 2.85–2.72 (m, 4H), 2.63–2.50 (m, 4H), 1.68–1.45 (m, 4H), 1.33–1.21 (m, 12H), 1.01–0.53 (m, 12H).

[0153] Comparative Example 1

[0154] This comparative example provides a catalyst E6 with the following structural formula, and the preparation method is as described in Example 1 of CN116444579A.

[0155]

[0156] Comparative Example 2

[0157] This comparative example provides a catalyst E7 with the following structural formula, and the preparation method is as described in Example 1 of CN116396338A.

[0158]

[0159] Comparative Example 3

[0160] This comparative example provides a method for preparing polyolefins using commercially available phenoxyimide zirconium as a catalyst.

[0161] Application Example 1

[0162] This application example provides a method for preparing a polyolefin, including the following steps:

[0163] The examples and comparative examples were used as the main catalysts, with tert-butylaluminoxane and tris(pentafluorophenyl)boron salt as co-catalysts. 1 μmol of the main catalyst was loaded into an ampoule in a high-pressure reactor, the temperature was set to 150°C, and the mixture was dried for 6 hours. A vacuum was then applied, and the temperature was gradually lowered to 25°C. 350 mL of Isopar E, 100 mL of 1-hexene, tert-butylaluminoxane, and tris(pentafluorophenyl)boron salt were added sequentially. The temperature was raised to 80-250°C, and ethylene monomer at 1-8 MPa was introduced. The ampoule was then broken, and the polymerization reaction was initiated. During the polymerization reaction, the stirring rate, polymerization temperature, and ethylene pressure remained constant. The reaction time was 5 minutes. After the reaction, the gas in the reactor was vented, the reaction liquid was neutralized, and a polymer precipitate was obtained. After washing several times and drying, the polyolefin product was obtained. The molar ratio of tert-butylaluminoxane to the main catalyst metal element is denoted as Al / M, and the molar ratio of B element in tris(pentafluorophenyl)boron salt to the main catalyst metal element M is denoted as B / M. The polymerization reaction temperature, ethylene pressure, Al / M, and B / M corresponding to the bimetallic catalysts used in the preparation of polyolefins in each embodiment are shown in Table 1.

[0164] Table 1. Reaction conditions for each embodiment and comparative example.

[0165]

[0166]

[0167] Test case

[0168] This test example provides the performance of polyolefins prepared using the examples and comparative examples as catalysts, as detailed below:

[0169] (1) Copolymerization activity: Calculated according to the following formula:

[0170]

[0171] The units for polymer mass are g, the units for metal content in catalyst are mol, and the units for polymerization reaction time are h.

[0172] (2) Weight average molecular weight Mw of polymer: The molecular weight of PL-GPC220 was obtained by testing at 160℃ using three PLgel 10μm MIXED-B separation columns in series, with 1,2,4-trichlorobenzene as solvent.

[0173] (3) The glass transition temperature was measured using the conventional DSC method.

[0174] (4) The double bonds at the ends of the polymer were calculated using the iodometric method.

[0175] (5) Molecular weight distribution of polymer: The molecular weight distribution was obtained by testing with PL-GPC220 at 150℃, using PLgel10μm MIXED-B separation columns in series, with 1,2,4-trichlorobenzene as solvent.

[0176] Table 2 Performance Test Results

[0177]

[0178]

[0179] The catalyst provided by this invention is applied to olefin polymerization and does not fail under high polymerization temperatures (e.g., 240°C). As a high-temperature resistant catalyst, it reduces the energy consumption of the olefin polymerization process. The polyolefins prepared by this catalyst have ultra-high molecular weight and narrow molecular weight distribution, high copolymerization activity, and low terminal double bond content, which helps to obtain polyolefin products with high tensile strength and high toughness. From the perspective of copolymerization activity, the polyolefins of this invention exhibit high copolymerization activity, which in turn indicates a high polyolefin yield.

[0180] As seen in Examples 1-5, by adjusting the types and amounts of R1-R3 and metal salts in the catalyst, this invention can control the molecular weight, molecular weight distribution, and terminal double bond content of the polymer, thereby obtaining polyolefin products with different properties and applying them to different fields. In particular, the polyolefin obtained by catalyst E2 provided in Example 2 has the best copolymerization activity and the highest molecular weight.

[0181] From Example 5 and Comparative Examples 1-3, when the polymerization temperature is 180°C, the polyolefins obtained in Comparative Examples 1-3 have lower molecular weights and lower copolymerization activity. Under the same polymerization conditions, the catalyst of the present invention has at least one order of magnitude higher copolymerization activity and molecular weight compared to Comparative Examples 1-3, and also has a narrow molecular weight distribution and low terminal double bond content. The catalyst of the present invention has good high-temperature resistance and still exhibits good activity under high-temperature polymerization conditions.

[0182] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A bimetallic catalyst based on a biphenylurea framework, characterized in that, Its structural formula is shown in Equation I; R1 is selected from hydrogen, C1-C20 alkyl, C3-C14 cycloalkyl, and any substituted or unsubstituted C6-C20 aryl; R2 is selected from C1 to C22 alkyl groups; R3 is selected from one of C1-C20 alkyl, C3-C14 cycloalkyl, C6-C20 aryl, C6-C20 aryloxy, and C6-C20 aromatic amino groups, whether substituted or unsubstituted. M is selected from Group IVB metallic elements; X is selected from halogens, C1-C20 alkyl groups, C6-C20 aryl groups, C6-C16 aralkyl groups, and C1-C20 alkylamino groups.

2. The bimetallic catalyst according to claim 1, characterized in that, Satisfy at least one of A to G: A. When R1 is selected from any aryl group of C6 to C20, the substituent is a C1 to C8 alkyl or a C1 to C8 alkoxy group; B. R1 is selected from hydrogen, methyl, ethyl, propyl, butyl, cyclopentyl, or phenyl; C. R2 is selected from methyl, ethyl, propyl, isopropyl, or tert-butyl; D. When R3 is selected from any aryl group of C6 to C20, the substituent is a C1 to C8 alkyl or a C1 to C8 alkoxy group; E. R3 is selected from methyl, ethyl, propyl, isopropyl, butyl, cyclopentyl, phenyl, tolyl, or tert-butylphenyl; F. M is selected from zirconium, titanium, or hafnium; G. X is selected from chlorine, bromine, methyl, benzyl or dimethylamino.

3. The bimetallic catalyst according to claim 1 or 2, characterized in that, The bimetallic catalyst shown in Formula I is selected from any of the following chemical substances represented by the following structural formulas:

4. A method for preparing a bimetallic catalyst based on a biphenylurea framework, characterized in that, Includes the following steps: (1) Compound A and 5-methyl-1,3,4-thiadiazole-2-amine react under alkaline conditions to form compound B; (2) Compound B reacts with compound C to form compound D; (3) The compound D undergoes a complexation reaction with the metal salt MX; Compound A has the following structural formula: The compound B has the following structural formula: Compound C is an isocyanate derivative with the following structural formula: The compound D has the following structural formula: R1 is selected from hydrogen, C1-C20 alkyl, C3-C14 cycloalkyl, and any substituted or unsubstituted C6-C20 aryl; R2 is selected from C1 to C22 alkyl groups; R3 is selected from one of C1-C20 alkyl, C3-C14 cycloalkyl, C6-C20 aryl, C6-C20 aryloxy, and C6-C20 aromatic amino groups, whether substituted or unsubstituted. M is selected from Group IVB metallic elements; X is selected from halogens, C1-C20 alkyl groups, C6-C20 aryl groups, C6-C16 aralkyl groups, and C1-C20 alkylamino groups.

5. The preparation method according to claim 4, characterized in that, Satisfy at least one of A to G: A. In step (1), the reaction temperature is 10-60℃ and the time is 1-5h; B. In step (1), an alkaline substance is used to provide the alkaline conditions; the alkaline substance includes at least one of triethylamine, sodium hydroxide, potassium hydroxide, sodium carbonate and pyridine; C. In step (1), the molar ratio of compound A and 5-methyl-1,3,4-thiadiazole-2-amine is 1:(2-4); D. In step (1), the molar ratio of compound A to the alkaline substance is 1:(2-5); E. In step (2), the reaction temperature is 30-120°C and the time is 2-8 hours. F. In step (2), the reaction is carried out under a protective atmosphere; G. In step (2), the molar ratio of compound B to compound C is 1:(2 to 2.8).

6. The preparation method according to claim 4, characterized in that, Step (3) satisfies at least one of A to E: A. The reaction temperature is 40℃~80℃, and the time is 1h~5h; B. The metal salt MX is selected from zirconium tetrachloride, titanium tetrachloride, hafnium tetrachloride, tetrabenzyl hafnium, tetra(dimethylamino)zirconium, titanium tetrabromide, zirconium tetrabromide or hafnium tetrabromide; C. The molar ratio of the compound D to the metal salt MX is 1:(2-4); D. Step (3) further includes the step of adding a dehydrogenating agent; The dehydrogenation reagent is at least one of alkyllithium, phenyllithium, potassium carbonate, sodium carbonate, potassium carbonate, and sodium hydride. Preferably, the dehydrogenating agent is at least one selected from n-butyllithium, methyllithium, and n-hexyllithium; E. The molar ratio of compound D to the dehydrogenating agent is 1:(4-7).

7. A catalyst for preparing polyolefins, characterized in that, The bimetallic catalyst includes the bimetallic catalyst according to any one of claims 1 to 3 or the bimetallic catalyst prepared by the preparation method according to any one of claims 4 to 6.

8. The catalyst according to claim 7, characterized in that, The catalyst further includes a co-catalyst, wherein the co-catalyst is at least one of alkylaluminum and borate; the co-catalyst satisfies at least one of A to D: A. The alkylaluminum is selected from C1 to C10 alkylaluminoxanes or alkyl-modified aluminumoxanes; Preferably, the alkylaluminum is methylaluminoxane, ethylaluminoxane, or tert-butylaluminoxane; B. The borate is selected from at least one or more of N,N-dimethylphenylamine tetra(pentafluorophenyl)borate, tripentafluorophenyl borate, and triphenylmethyltetra(pentafluorophenyl) borate; Preferably, the borate is trifluorophenyl borate; C. Based on the metal element Al in the alkylaluminum and the metal element M in the bimetallic catalyst, the molar ratio of the alkylaluminum to the bimetallic catalyst is (5-400):

1. D. Based on element B in the borate and metal element M in the bimetallic catalyst, the molar ratio of the borate to the bimetallic catalyst is (0-25):

1.

9. A method for preparing a polyolefin, characterized in that, include: The olefins are polymerized under the action of the catalyst described in claim 7 or 8.

10. The preparation method according to claim 9, characterized in that, The preparation method satisfies at least one of A to B: A. The olefin is selected from at least one of ethylene, propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, styrene, and norbornene; B. The polymerization reaction is carried out at a temperature of 50–300°C and a pressure of 0.1–20 MPa. Preferably, the polymerization reaction is carried out at a temperature of 80–250°C and a pressure of 1–8 MPa.

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