A supported transition metal catalyst system and its preparation and application

Abstract

This invention relates to a supported transition metal catalyst system, its preparation, and its application. The catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst, composed of a transition metal salt and a support, the surface of which contains one or more hydroxyl, mercapto, and nitrogen atoms. The co-catalyst is an alkylaluminum compound or an aluminoxane compound. The transition metal salt and the support are mixed in an organic solvent to prepare a supported transition metal catalyst linked by coordination, which is then reacted with the co-catalyst to obtain the supported transition metal catalyst system. This system is applied to the preparation of linear α-olefins and olefin polymers. The preparation method of this invention is simple; the obtained catalyst system is not only effective for olefin oligomerization but also catalyzes olefin polymerization to obtain high molecular weight polymers; this invention exhibits good product selectivity when used to prepare linear α-olefins and can produce high-density polyethylene when used to prepare olefin polymers.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and relates to a supported transition metal catalyst system and its preparation and application. Background Technology

[0002] Linear α-olefins (LAO) generally refer to C4 and above straight-chain 1-olefins. They are an important organic raw material that has developed rapidly in recent years and has a wide range of applications. Depending on the number of carbon atoms, they are used in many industries.

[0003] Low-carbon-number ethylene oligomers can be used to prepare comonomers for advanced polyolefins. Among them, 1-butene, 1-hexene, and 1-octene copolymerized with ethylene can prepare high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and polyolefin elastomers (POE).

[0004] Currently, commercial ethylene oligomerization processes use homogeneous catalysts composed of transition metal (such as Ni, Ti) complexes. Homogeneous catalysts are divided into selective oligomerization catalysts and non-selective oligomerization catalysts.

[0005] The SHOP process described in references 1 (Oligomerization of Ethylene to α-Olefins: Discovery and Development of the Shell Higher Olefin Process (SHOP). Angewandte Chemie International Edition 2013, 52(48), 12492-12496.), US Patent 3,647,914,1972, US Patent 3,686,159,1972, US Patent 3,676,523,1972, and US Patent 4,020,121,1977) uses a non-selective oligomerization catalyst for production. This process has a long route and the product distribution can be flexibly selected. The mass fraction of α-olefins is higher than 98%, but the carbon number range of the product is wide (a wide carbon number range means poor catalyst selectivity). To obtain high-purity ethylene oligomers, such as 1-butene, 1-hexene, or 1-octene, further separation and purification are required.

[0006] The preparation of 1-octene from the tetramerization of 1-hexene and ethylene can be achieved through selective ethylene oligomerization (i.e., using a selective oligomerization catalyst). Currently, a mature oligomerization process for the selective trimerization of ethylene to prepare 1-hexene has been established internationally. References 2 (Process for the preparation of a catalyst for olefin polymerization: EP, 0608447B2 [P]. 1994-08-03.) and 3 (Preparation of an olefin oligomerization catalyst: US, 2013150642A1 [P]. 2013-06-13.) record that the process of producing 1-hexene using a chromium-based catalyst can achieve a 1-hexene selectivity of 92-98%.

[0007] However, the current industrial production of 1-butene is still based on non-selective ethylene oligomerization. To obtain high-purity 1-butene, the product still needs to be separated and purified.

[0008] To shorten the production process and eliminate the separation and purification steps, it is necessary to improve the selectivity of 1-butene in the polymerization product. Current technologies typically involve designing catalysts with specific structures, but this complicates the synthesis route and increases production costs. Although these homogeneous catalysts exhibit high selectivity and activity, homogeneous catalyst oligomerization also suffers from problems such as short catalyst lifetime, difficulty in separating from the product, and challenges in achieving industrial recycling of the catalyst.

[0009] To address the aforementioned issues, existing technologies introduce solid supports into homogeneous catalyst systems to prepare heterogeneous supported catalysts (heterogeneous catalysts). This method utilizes the combination of homogeneous catalysts and supports to achieve a loading effect, allowing the metal active sites to be fully dispersed on the support surface. Therefore, it requires the prior synthesis of homogeneous catalysts, which is complex and increases industrialization costs. Furthermore, most homogeneous catalysts exhibit reduced polymerization activity after loading, limiting their large-scale application. For example, the β-diimine nickel(II) complex described in reference 4 (Ethylene oligomerization using nickel-β-diimine hybrid xerogels produced by the sol–gel process. Applied Catalysis A: General, 2013, 454(15), 152-159.) can efficiently catalyze the dimerization of ethylene to butene (94-100%). C4); among them, the β-diimine nickel(II) / SiO2 heterogeneous catalyst generated by loading the β-diimine nickel(II) complex of this structure onto SiO2 using the sol-gel method will have an activity that is 1 to 2 orders of magnitude lower than that of the original homogeneous catalyst.

[0010] In addition, Ziegler-Natta or Phillips catalysts are commonly used in the industrial production of polyethylene. Reference 5 (Das Mülheimer Normaldruck- According to Verfahren, Angewandte Chemie 1955, 67, 541-547. and reference 6 (Une nouvelle classe de polymeres d'α-olefines ayant une régularitédestructure exceptionnelle. Journal of Polymer Science 1955, 16, 143-154.), the Ziegler-Natta catalyst used industrially is a heterogeneous catalyst with multiple active sites. However, some of these active sites lack stereoselectivity, resulting in a complex catalytic reaction mechanism and a wide range of polymer molecular weights. In early Ziegler-Natta catalysts, metal atoms exposed on the crystal surface, edges, or defects that serve as active sites (such as Ti atoms in TiCl4) accounted for only 1%, which was the main reason for the low activity. Reference 7 (JP Hogan and R.L. Banks. Polymerization of olefins: US Patent 2825721.1958.) describes that the Phillips catalyst is a heterogeneous supported Cr-based catalyst with a typically low active component loading (0.2-2 wt%). It generally needs to be activated at high temperature before it can be used to catalyze ethylene polymerization. Its surface coordination environment is complex, and there are few active centers in actual reactions.

[0011] Therefore, it is of great significance to study a supported transition metal catalyst system with high activity and high selectivity, as well as its preparation and application, in order to solve the above problems. Summary of the Invention

[0012] The purpose of this invention is to solve the problems existing in the prior art and to provide a supported transition metal catalyst system and its preparation and application.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] A supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst, which is composed of a metal salt of a transition metal (which can be a pre-transition metal or a post-transition metal, both of which are within the scope of protection of this invention) and a support. The surface of the support contains one or more of hydroxyl groups, mercapto groups, and nitrogen atoms. One or more of the hydroxyl groups, mercapto groups, and nitrogen atoms on the surface of the support interact with the transition metal to form coordination bonds. The co-catalyst is an alkylaluminum compound or an aluminum oxane compound.

[0015] The co-catalyst in this invention has three main functions, as follows: (1) the co-catalyst alkylates the main catalyst; (2) the main catalyst must be activated by a suitable and efficient co-catalyst to become a true active center. In this system, the cation active center of the main catalyst can proceed to the next step of ethylene insertion after activation by the co-catalyst; (3) the co-catalyst can clean up impurities in the system, so that the cation active center can exist stably.

[0016] The catalyst system of this invention is not only effective for olefin oligomerization, but also catalyzes olefin polymerization to obtain high molecular weight polymer products.

[0017] As a preferred technical solution:

[0018] The supported transition metal catalyst system described above, wherein the transition metal is Ni, Pd, Cr, Co or Fe, and the metal salt of the transition metal includes, but is not limited to, nickel chloride, palladium chloride, nickel bromide, palladium bromide, chromium chloride, etc., and all metal salts that can coordinate with surface functional groups are within the protection scope of this invention.

[0019] In the supported transition metal catalyst system described above, the amount of metal salt added to the transition metal is such that the metal loading of the support is 0.1 to 10 wt%.

[0020] The supported transition metal catalyst system described above uses SiO2, ZrO2, TiO2, MgO, Fe3O4, SiS2, ZrS2, TiS2, MgS, Fe3S4, activated carbon, C3N4, carbon nanotubes, BN, or cellulose as the support, and the particle size of the support is in the micrometer or nanometer range.

[0021] In the supported transition metal catalyst system described above, the alkyl aluminum compound is trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, sesquiethylaluminum chloride, or diethylaluminum chloride, and the aluminum oxoalkane compound is methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or tert-butylaluminoxane.

[0022] The present invention also provides a method for preparing a supported transition metal catalyst system as described in any of the preceding claims, wherein a metal salt of a transition metal and a support are mixed in an organic solvent to prepare a supported transition metal catalyst linked by coordination, and the supported transition metal catalyst reacts with a co-catalyst to obtain a supported transition metal catalyst system composed of anion-cation pairs of active centers, as shown below.

[0023] In the formula, L is a ligand, M is a transition metal, X is a halogen atom, and R is an alkyl group;

[0024] The organic solvent is a good solvent for transition metal salts and a poor solvent for the support; the organic solvent is selected from C6-C9 aromatics, halogenated aromatics or C3-C20 alkanes, with benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene or monochlorotoluene being preferred aromatics; butane, pentane, hexane, cyclohexane or heptane being preferred alkanes; and toluene being more preferred organic solvent.

[0025] As a preferred technical solution:

[0026] The preparation method of the supported transition metal catalyst system described above includes the following specific steps:

[0027] (1) Under the protection of nitrogen or inert gas, the metal salt of the transition metal is dissolved in an organic solvent at a temperature of 10 to 30°C and a pressure of atmospheric pressure to obtain an organic solution of the metal salt.

[0028] (2) The support was immersed in an organic solution of metal salt at a temperature of room temperature to 85°C (different solvents were used for different metal salts; room temperature was used for acetonitrile with a lower boiling point, and 85°C was used for DMF with a higher boiling point) and a pressure of atmospheric pressure. After the reaction, the support was washed and dried to obtain a supported transition metal catalyst.

[0029] (3) The supported transition metal catalyst system is obtained by the interaction of the supported transition metal catalyst and the co-catalyst.

[0030] The present invention also provides a method for preparing linear α-olefins by ethylene oligomerization as described in any of the preceding claims, wherein the linear α-olefin is 1-butene (C4) or 1-hexene (C6);

[0031] Linear α-olefins are prepared by polymerization of a supported transition metal catalyst and a co-catalyst at a temperature of 0–100 °C (preferably 20–40 °C) and a pressure of 1.0–5.0 MPa (preferably 2.0–4.0 MPa).

[0032] The supported transition metal catalyst and co-catalyst are the supported transition metal catalyst and co-catalyst in the supported transition metal catalyst system as described above; the transition metal is Ni;

[0033] The molar ratio of supported transition metal catalyst to co-catalyst is 1:50 to 1000.

[0034] The oligomers obtained by this method have both high activity and high selectivity. The types and distribution of products can be controlled by changing the type of co-catalyst.

[0035] As a preferred technical solution:

[0036] The method for preparing linear α-olefins by ethylene oligomerization as described above, wherein the linear α-olefin is 1-butene, and the catalytic activity is 0.28–9.96 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene is greater than 91.4%.

[0037] The present invention also provides a method for preparing olefin polymers, wherein a supported transition metal catalyst and a co-catalyst are subjected to a polymerization reaction at a temperature of 0 to 100°C and a pressure of 1.0 to 5.0 MPa to obtain olefin polymers;

[0038] The supported transition metal catalyst and the co-catalyst are respectively the supported transition metal catalyst and the co-catalyst in the supported transition metal catalyst system as described in any of the preceding claims; the transition metal is Pd, Cr, Co or Fe;

[0039] The molar ratio of supported transition metal catalyst to co-catalyst is 1:50 to 1000.

[0040] Invention principle:

[0041] In existing ethylene oligomerization processes, improving the selectivity of 1-butene in the polymerization product requires the design of homogeneous catalysts with specific structures, thus complicating the catalyst synthesis route and increasing production costs. Currently used industrial homogeneous catalysts have short lifespans, are difficult to separate from the product, and hinder industrial recycling. Furthermore, the carbon number distribution of the products from current industrial ethylene oligomerization catalysts is relatively wide, requiring lengthy process routes for further purification and separation. Moreover, existing technologies utilize heterogeneous supported catalysts obtained by combining homogeneous catalysts with supports for ethylene oligomerization reactions. While the original homogeneous catalyst can be used for ethylene oligomerization before support, its activity decreases after support compared to the original homogeneous catalyst.

[0042] The catalyst system of this invention utilizes the coordination bonds formed between hydroxyl / thiol / N atoms on the metal oxide and the metal, thereby directly loading the metal onto the support to form a supported catalyst. The supported transition metal catalyst interacts with a co-catalyst to obtain a supported transition metal catalyst system composed of cation-anion pairs with active centers. This direct supported catalyst through coordination is similar in loading to traditional direct supported catalysts formed by directly connecting homogeneous catalysts and supports via covalent bonds. However, the method of this invention directly uses metal salts instead of traditional homogeneous catalysts, making the synthesis method simpler. Furthermore, inexpensive metal salts themselves have very low catalytic activity, but exhibit high catalytic activity after being supported, and the catalytic effect is not significantly reduced compared to traditional homogeneous catalysts. The reason why the supported metal salts of this invention exhibit catalytic activity is that the olefin polymerization catalyst adjusts the electronic state of the metal through the coordination of heteroatoms on the support, making it suitable for the coordination and insertion of olefins; this is also suitable in this invention.

[0043] The loading method of this invention not only leverages the characteristics of heterogeneous transition metal catalysis and solves the problem of catalyst and product separation in existing olefin polymerization production where homogeneous catalysts are unsuitable, enabling catalyst recycling, but also avoids complex synthesis processes and the use of expensive co-catalysts (such as MAO, MMAO, and other aluminum oxane compounds), thus significantly saving costs.

[0044] In existing catalyst systems, forming a supported form typically requires complex processing techniques. For example, Phillips-type catalysts, as the earliest industrialized chromium-based catalysts, typically use CrO2 to form a supported form. x The catalyst is supported on a carrier such as silica gel. This process requires high-temperature calcination at 400–1000 °C to allow the CrO to mature. x The esterification reaction occurs with the hydroxyl groups on the surface of the silicone, and Cr is fixed on the surface of the silicone in the form of chromate to form active centers. Moreover, the metal salt loading can be completed at room temperature, laying the foundation for further industrial applications.

[0045] The catalyst system of this invention has high selectivity for 1-butene because Ni serves as the active center for catalytic ethylene oligomerization via the Cossee-Arlman chain growth mechanism. The termination of the ethylene oligomerization chain growth occurs through competitive β-H elimination. The inexpensive metal salt is directly loaded onto the support surface, giving the structure open coordination sites, which is conducive to the occurrence of β-H elimination of ethylene and thus promotes the generation of C4.

[0046] Furthermore, the supported transition metal catalyst system of the present invention can also catalyze olefin polymerization to obtain polymer products with high molecular weight and narrow molecular weight distribution by regulating β-H elimination through the polymerization mechanism of different metals.

[0047] Beneficial effects:

[0048] (1) The preparation method of the present invention utilizes a supported transition metal catalyst in which metal salts are directly connected to inorganic oxides / sulfides / nitrides through coordination. Using a cheap and simple loading method, a heterogeneous catalytic system with industrial application potential is successfully prepared. The polymerization mechanism of different metals is used to regulate β-H elimination, thereby controlling the molecular weight of the product to obtain a polymer product with uniform molecular weight. By controlling the polymerization temperature, side reactions such as isomerization of oligomerized product 1-olefin are reduced, while the molecular weight is controlled.

[0049] (2) The present invention provides a method for preparing linear α-olefins by ethylene oligomerization, which can improve the selectivity of the product under the combined action of the main catalyst and the co-catalyst, so that the selectivity of the final 1-butene is greater than 91.4%.

[0050] (3) The supported transition metal catalyst system of the present invention is not only effective for olefin oligomerization, but also can catalyze olefin polymerization to obtain high molecular weight polymer products.

[0051] (4) The method for preparing an olefin polymer of the present invention yields an olefin polymer with a high molecular weight. Attached Figure Description

[0052] Figure 1 The gas chromatogram of the polymerization product in Example 16;

[0053] Figure 2 The DSC spectrum of the polymerization product in Example 17;

[0054] Figure 3 This is the molecular weight distribution spectrum of the polymer product in Example 19. Detailed Implementation

[0055] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0056] The test methods involved in the embodiments are as follows:

[0057] Selectivity: After the polymerization reaction is complete, the ethylene valve and stirring are closed, and the reactor is cooled in liquid nitrogen. When the temperature of the reaction system drops to -20℃, the unreacted ethylene in the reactor is discharged until atmospheric pressure is reached. The reactor is then opened, and the reaction solution is collected. 100 μL of cyclopentene standard is added to the solution as an internal standard. After mixing thoroughly, GC-MS characterization is performed to obtain the proportion of each component in the total product. The same detector (i.e., GC-MS) has different response values ​​for different substances. Therefore, when different types of substances of the same mass pass through the detector, the peak areas produced are not necessarily equal. To ensure that the peak area accurately reflects the content of the analyte, the peak area of ​​the analyte (standard substance) under the chromatographic conditions used needs to be determined using a known amount of the analyte (standard substance) to calculate the quantitative correction factor. The relative correction factor is the multiple of the peak area of ​​the standard substance to the peak area of ​​component i when the mass of analyte i is equal to that of standard substance s, denoted as f. i If the mass of a certain component is m i Peak area A i Then f i With A i The product of these two terms represents the peak area A corresponding to a standard substance with mass m. s .

[0058] Catalytic activity: The mass of product (butene) produced per unit amount of catalyst per unit time (hour); the amount of cyclopentene added each time is 100 μL, i.e., m = 0.0771 g; the amount of catalyst used is n (mol), the polymerization time is t (h), and the formula for calculating catalytic activity is as follows:

[0059]

[0060] The unit of catalytic activity is kgmol -1 h -1 .

[0061] Some of the experimental reagents used in the examples are shown in Table 1:

[0062] Table 1

[0063]

[0064]

[0065] Example 1

[0066] A method for preparing a supported transition metal catalyst system, comprising the following specific steps:

[0067] (1) Under nitrogen protection, nickel dimethyl ether ethylene glycol bromide was dissolved in anhydrous acetonitrile at a temperature of 10°C and a pressure of atmospheric pressure to obtain an acetonitrile solution of nickel dimethyl ether ethylene glycol bromide.

[0068] (2) Nanoscale ZrO2 was impregnated in an acetonitrile solution of ethylene glycol dimethyl ether nickel bromide at room temperature and atmospheric pressure. After reacting for 48 h, the product was washed three times with anhydrous acetonitrile to remove unreacted ethylene glycol dimethyl ether nickel bromide. Then, it was vacuum dried at 40 °C for 18 h to obtain a supported transition metal catalyst. The amount of ethylene glycol dimethyl ether nickel bromide added was sufficient to make the metal loading of ZrO2 2.2 wt%.

[0069] (3) The supported transition metal catalyst reacts with dichloroethylaluminum to obtain a supported transition metal catalyst system composed of active center anions and cations.

[0070] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of nickel bromide in ethylene glycol dimethyl ether and ZrO2. The hydroxyl groups on the surface of ZrO2 interact with nickel to form coordination bonds; the co-catalyst is dichloroethylaluminum.

[0071] Example 2

[0072] A method for preparing a supported transition metal catalyst system is basically the same as in Example 1, except that the co-catalyst is diethylaluminum chloride.

[0073] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of nickel bromide in ethylene glycol dimethyl ether and ZrO2. The hydroxyl groups on the surface of ZrO2 interact with nickel to form coordination bonds; the co-catalyst is diethylaluminum chloride.

[0074] Example 3

[0075] A method for preparing a supported transition metal catalyst system is basically the same as in Example 1, except that the co-catalyst is methylaluminoxane.

[0076] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of ethylene glycol dimethyl ether nickel bromide and ZrO2. The hydroxyl groups on the surface of ZrO2 interact with nickel to form coordination bonds; the co-catalyst is methylaluminoxane.

[0077] Example 4

[0078] A method for preparing a supported transition metal catalyst system, comprising the following specific steps:

[0079] (1) Under nitrogen protection, nickel dimethyl ether ethylene glycol bromide was dissolved in anhydrous acetonitrile at a temperature of 15°C and a pressure of atmospheric pressure to obtain an acetonitrile solution of nickel dimethyl ether ethylene glycol bromide.

[0080] (2) Micron-sized SiO2 was immersed in an acetonitrile solution of ethylene glycol dimethyl ether nickel bromide at room temperature and atmospheric pressure. After reacting for 48 h, the product was washed three times with anhydrous acetonitrile to remove unreacted ethylene glycol dimethyl ether nickel bromide. Then, it was vacuum dried at 40 °C for 18 h to obtain a supported transition metal catalyst. The amount of ethylene glycol dimethyl ether nickel bromide added was sufficient to make the metal loading of SiO2 3.4 wt%.

[0081] (3) The supported transition metal catalyst reacts with dichloroethylaluminum to obtain a supported transition metal catalyst system composed of active center anions and cations.

[0082] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of nickel bromide in ethylene glycol dimethyl ether and SiO2. The hydroxyl groups on the surface of SiO2 interact with nickel to form coordination bonds; the co-catalyst is dichloroethylaluminum.

[0083] Example 5

[0084] A method for preparing a supported transition metal catalyst system, comprising the following specific steps:

[0085] (1) Under nitrogen protection, nickel chloride hexahydrate was dissolved in anhydrous DMF at a temperature of 20°C and a pressure of atmospheric pressure to obtain a DMF solution of nickel chloride hexahydrate;

[0086] (2) Micron-sized SiO2 was immersed in a DMF solution of nickel chloride hexahydrate at a temperature of 85°C and a pressure of atmospheric pressure. After reacting for 48 h, the product was washed three times with anhydrous DMF to remove unreacted nickel chloride hexahydrate. Then, it was washed three times with anhydrous acetonitrile to replace the DMF. Finally, it was vacuum dried at 40°C for 18 h to obtain a supported transition metal catalyst. The amount of nickel chloride hexahydrate added was sufficient to make the metal loading of SiO2 5.4 wt%.

[0087] (3) The supported transition metal catalyst reacts with dichloroethylaluminum to obtain a supported transition metal catalyst system composed of active center anions and cations.

[0088] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of nickel chloride hexahydrate and SiO2, with hydroxyl groups on the surface of SiO2 interacting with nickel to form coordination bonds; the co-catalyst is dichloroethylaluminum.

[0089] Example 6

[0090] A method for preparing a supported transition metal catalyst system, comprising the following specific steps:

[0091] (1) Under nitrogen protection, chromium dichloride was dissolved in anhydrous DMF at a temperature of 25°C and a pressure of atmospheric pressure to obtain a DMF solution of chromium dichloride.

[0092] (2) Micron-sized SiO2 was immersed in a DMF solution of chromium dichloride at a temperature of 85°C and a pressure of atmospheric pressure. After reacting for 48 h, the product was washed three times with anhydrous DMF to remove unreacted chromium dichloride. Then it was washed three times with anhydrous acetonitrile to replace the DMF. Finally, it was vacuum dried at 40°C for 18 h to obtain a supported transition metal catalyst. The amount of chromium dichloride added was sufficient to make the metal loading of SiO2 4 wt%.

[0093] (3) The supported transition metal catalyst reacts with dichloroethylaluminum to obtain a supported transition metal catalyst system composed of active center anions and cations.

[0094] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of chromium dichloride and SiO2, with hydroxyl groups on the surface of SiO2 interacting with chromium to form coordination bonds; the co-catalyst is dichloroethylaluminum.

[0095] Example 7

[0096] A method for preparing a supported transition metal catalyst system, comprising the following specific steps:

[0097] (1) Under nitrogen protection, cobalt chloride was dissolved in anhydrous DMF at a temperature of 30°C and a pressure of atmospheric pressure to obtain a DMF solution of cobalt chloride.

[0098] (2) Micron-sized SiO2 was immersed in a DMF solution of cobalt chloride at a temperature of 85°C and a pressure of atmospheric pressure. After reacting for 48 h, the product was washed three times with anhydrous DMF to remove unreacted cobalt chloride. Then it was washed three times with anhydrous acetonitrile to replace DMF. Finally, it was vacuum dried at 40°C for 18 h to obtain a supported transition metal catalyst. The amount of cobalt chloride added was sufficient to make the metal loading of SiO2 3.6 wt%.

[0099] (3) The supported transition metal catalyst reacts with dichloroethylaluminum to obtain a supported transition metal catalyst system composed of active center anions and cations.

[0100] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of cobalt chloride and SiO2, with hydroxyl groups on the surface of SiO2 interacting with cobalt to form coordination bonds; the co-catalyst is dichloroethylaluminum.

[0101] Example 8

[0102] A method for preparing a supported transition metal catalyst system, comprising the following specific steps:

[0103] (1) Under argon protection, ferrous chloride was dissolved in anhydrous DMF at a temperature of 25°C and a pressure of atmospheric pressure to obtain a DMF solution of ferrous chloride.

[0104] (2) Micron-sized C3N4 was immersed in a DMF solution of ferrous chloride at a temperature of 85°C and a pressure of atmospheric pressure. After reacting for 48 h, the product was washed three times with anhydrous DMF to remove unreacted ferrous chloride, and then washed three times with anhydrous acetonitrile to replace DMF. The product was then vacuum dried at 40°C for 18 h to obtain a supported transition metal catalyst. The amount of ferrous chloride added was sufficient to satisfy the metal loading of C3N4 of 1.2 wt%.

[0105] (3) The supported transition metal catalyst reacts with methylaluminoxane to obtain a supported transition metal catalyst system composed of active center anions and cations.

[0106] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of ferrous chloride and C3N4, with the amino groups on the surface of C3N4 interacting with iron to form coordinate bonds; the co-catalyst is methylaluminoxane.

[0107] Example 9

[0108] A method for preparing a supported transition metal catalyst system, comprising the following specific steps:

[0109] (1) Under nitrogen protection, palladium chloride was dissolved in anhydrous DMF at a temperature of 25°C and a pressure of atmospheric pressure to obtain a DMF solution of palladium chloride;

[0110] (2) Micron-sized ZrS2 was immersed in a DMF solution of palladium chloride at a temperature of 85°C and a pressure of atmospheric pressure. After reacting for 48 h, the product was washed three times with anhydrous DMF to remove unreacted palladium chloride. Then, it was washed three times with anhydrous acetonitrile to replace the DMF. Finally, it was vacuum dried at 40°C for 18 h to obtain a supported transition metal catalyst. The amount of palladium chloride added was sufficient to make the metal loading of ZrS2 6.2 wt%.

[0111] (3) The supported transition metal catalyst reacts with methylaluminoxane to obtain a supported transition metal catalyst system composed of active center anions and cations.

[0112] The prepared supported transition metal catalyst system includes a main catalyst and a co-catalyst. The main catalyst is a supported transition metal catalyst with the following structural formula: It is composed of palladium chloride and ZrS2, with the thiol groups on the surface of ZrS2 interacting with palladium to form coordination bonds; the cocatalyst is methylaluminoxane.

[0113] Example 10

[0114] A method for preparing 1-butene by ethylene oligomerization, the specific process of which is as follows:

[0115] The supported transition metal catalyst prepared in Example 1 and a 0.1 M toluene solution of dichloroethylaluminum were polymerized at 20 °C and 2 MPa to produce 1-butene. After the reaction, the reactor was cooled to -20 °C with liquid nitrogen. Cyclopentene was used as an internal standard, and the catalytic activity and carbon number distribution of the product were determined by gas chromatography-mass spectrometry.

[0116] The transition metal is Ni, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:80.

[0117] The catalytic activity is 1.89 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene was 95.2%.

[0118] Example 11

[0119] A method for preparing 1-butene by ethylene oligomerization is basically the same as in Example 10, except that the polymerization temperature is 0°C.

[0120] The catalytic activity is 0.28 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene was 96.1%.

[0121] Example 12

[0122] A method for preparing 1-butene by ethylene oligomerization is basically the same as in Example 10, except that the molar ratio of the supported transition metal catalyst and the co-catalyst is 1:160.

[0123] The catalytic activity is 6.17 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene was 93.8%.

[0124] Example 13

[0125] A method for preparing 1-butene and 1-hexene by ethylene oligomerization, the specific process of which is as follows:

[0126] The supported transition metal catalyst prepared in Example 2 and a 1.8 M diethylaluminum chloride toluene solution were polymerized at 20 °C and 2 MPa to produce 1-butene and 1-hexene. After the reaction, the reactor was cooled to -20 °C with liquid nitrogen. Cyclopentene was used as an internal standard, and the catalytic activity and carbon number distribution of the products were determined by gas chromatography-mass spectrometry.

[0127] The transition metal is Ni, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:1000.

[0128] The catalytic activity is 3.79 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The product is mainly 1-hexene, with a selectivity of 65.7%.

[0129] Example 14

[0130] A method for preparing 1-butene by ethylene oligomerization, the specific process of which is as follows:

[0131] The supported transition metal catalyst prepared in Example 3 and a 1.5 M toluene solution of methylaluminoxane were polymerized at 20 °C and 2 MPa to obtain 1-butene. After the reaction, the reactor was cooled to -20 °C with liquid nitrogen. Cyclopentene was used as an internal standard, and the catalytic activity and carbon number distribution of the product were determined by gas chromatography-mass spectrometry.

[0132] The transition metal is Ni, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:1000.

[0133] The catalytic activity is 5.26 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene was 92.4%.

[0134] Example 15

[0135] A method for preparing 1-butene by ethylene oligomerization, the specific process of which is as follows:

[0136] The supported transition metal catalyst prepared in Example 4 and a 0.1 M toluene solution of dichloroethylaluminum were polymerized at 20 °C and 2 MPa to produce 1-butene. After the reaction, the reactor was cooled to -20 °C with liquid nitrogen. Cyclopentene was used as an internal standard, and the catalytic activity and carbon number distribution of the product were determined by gas chromatography-mass spectrometry.

[0137] The transition metal is Ni, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:80.

[0138] The catalytic activity is 2.95 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene is 95%.

[0139] Example 16

[0140] A method for preparing 1-butene by ethylene oligomerization, the specific process of which is as follows:

[0141] The supported transition metal catalyst prepared in Example 5 and a 0.1 M solution of dichloroethylaluminum in toluene were polymerized at 20°C and 2 MPa to produce 1-butene. After the reaction, the reactor was cooled to -20°C with liquid nitrogen. Cyclopentene was used as an internal standard, and the catalytic activity and carbon number distribution of the product were determined by gas chromatography-mass spectrometry. Figure 1 As shown.

[0142] The transition metal is Ni, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:80.

[0143] The catalytic activity is 1.57 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene was 94.4%.

[0144] Example 17

[0145] A method for preparing an olefin polymer, the specific process of which is as follows:

[0146] The supported transition metal catalyst prepared in Example 6 and a 1.5 M solution of dichloroethylaluminum in toluene were polymerized at 60°C and 2 MPa to obtain an olefin polymer. EtOH was added to the reaction system to precipitate the product. The structure and molecular weight of the product were determined by NMR and high-temperature gel permeation chromatography. Figure 2 It can be determined that the product is high-density polyethylene.

[0147] The transition metal is Cr, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:500.

[0148] The catalytic activity is 0.65 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The number-average molecular weight of the olefin polymer is 2.58 × 10⁻⁶. 3 The molecular weight distribution is 2.46.

[0149] Example 18

[0150] A method for preparing an olefin polymer, the specific process of which is as follows:

[0151] The supported transition metal catalyst prepared in Example 7 and a 0.1 M toluene solution of dichloroethylaluminum were polymerized at 20 °C and 2 MPa to obtain an olefin polymer. EtOH was added to the reaction system to precipitate the product, and the structure and molecular weight of the product were determined by NMR and high-temperature gel permeation chromatography.

[0152] The transition metal is Co, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:500.

[0153] The catalytic activity is 1.11 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The number-average molecular weight of the olefin polymer is 70.04 × 10⁻⁶. 3 The molecular weight distribution is 2.29.

[0154] Example 19

[0155] A method for preparing an olefin polymer, the specific process of which is as follows:

[0156] The supported transition metal catalyst prepared in Example 8 and a 0.1 M toluene solution of methylaluminoxane were polymerized at 40 °C and 2 MPa to obtain an olefin polymer. EtOH was added to the reaction system to precipitate the product. The structure and molecular weight of the product were determined by NMR and high-temperature gel permeation chromatography. Figure 3 As shown.

[0157] The transition metal is Fe, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:1000.

[0158] The catalytic activity is 1.87 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The molecular weight of the olefin polymer is 10.6 × 10⁻⁶. 3 The molecular weight distribution is 2.39.

[0159] Example 20

[0160] A method for preparing an olefin polymer, the specific process of which is as follows:

[0161] The supported transition metal catalyst prepared in Example 9 and a 0.1 M toluene solution of methylaluminoxane were polymerized at 40 °C and 2 MPa to obtain an olefin polymer. EtOH was added to the reaction system to precipitate the product, and the structure and molecular weight of the product were determined by nuclear magnetic resonance and high-temperature gel permeation chromatography.

[0162] The transition metal is Pd, and the molar ratio of the supported transition metal catalyst to the co-catalyst is 1:1000.

[0163] The catalytic activity is 2.64 × 10⁻⁶. 3 Kg·mol -1 ·h -1 The molecular weight of the olefin polymer is 4.68 × 10⁻⁶. 3 The molecular weight distribution is 2.90.

Claims

1. An application of a supported transition metal catalyst, characterized in that: Used for the oligomerization of ethylene to prepare linear α-olefins, wherein the linear α-olefins are 1-butene or 1-hexene; Supported transition metal catalysts consist of a metal salt of a transition metal and a support. The transition metal is Ni, Pd, Cr, Co, or Fe. The surface of the support contains one or more of hydroxyl, mercapto, and nitrogen atoms. One or more of the hydroxyl, mercapto, and nitrogen atoms on the surface of the support interact with the transition metal to form coordination bonds. Linear α-olefins were prepared by polymerization using a supported transition metal catalyst as the main catalyst and an alkylaluminum compound or an aluminum oxane compound as a co-catalyst, under conditions of 0~100℃ and 1.0~5.0MPa.

2. The application of the supported transition metal catalyst according to claim 1, characterized in that, The amount of transition metal salt added is sufficient to make the metal loading of the support 0.1~10wt%.

3. The application of the supported transition metal catalyst according to claim 1, characterized in that, The support can be SiO2, ZrO2, TiO2, MgO, Fe3O4, SiS2, ZrS2, TiS2, MgS, Fe3S4, activated carbon, C3N4, carbon nanotubes, BN, or cellulose, and the particle size of the support can be in the micrometer or nanometer range.

4. The application of the supported transition metal catalyst according to claim 1, characterized in that, The alkylaluminum compounds are trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, sesquiethylaluminum chloride, or dichloroethylaluminum, and the aluminum oxoalkane compounds are methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or tert-butylaluminoxane.

5. The application of the supported transition metal catalyst according to claim 1, characterized in that, A supported transition metal catalyst was prepared by mixing a transition metal salt with a support in an organic solvent. Organic solvents are good solvents for transition metal salts, but poor solvents for the support.

6. The application of the supported transition metal catalyst according to claim 5, characterized in that, The specific steps for using supported transition metal catalysts are as follows: (1) Under the protection of nitrogen or inert gas, the metal salt of the transition metal is dissolved in an organic solvent at a temperature of 10~30°C and a pressure of atmospheric pressure to obtain an organic solution of the metal salt; (2) The support was immersed in an organic solution of metal salt at a temperature of room temperature to 85°C and a pressure of normal pressure. After the reaction, the support was washed and dried to obtain a supported transition metal catalyst.

7. The application of the supported transition metal catalyst according to claim 1, characterized in that, The transition metal is Ni; The molar ratio of the main catalyst to the co-catalyst is 1:50~1000.

8. The application of the supported transition metal catalyst according to claim 7, characterized in that, The linear α-olefin is 1-butene, with a catalytic activity of 0.28~9.96×10⁻⁶. 3 Kg·mol -1 ·h -1 The selectivity for 1-butene is greater than 91.4%.

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