A high-performance organic framework olefin polymerization catalyst and its preparation method

Abstract

This application belongs to the technical field of olefin polymerization catalysts and specifically provides a high-performance organic framework olefin polymerization catalyst and its preparation method, comprising the following steps: 1) synthesizing zirconium-based MOFs; 2) impregnating succinate into the pores of the zirconium-based MOFs; 3) loading an [N,P]-type zirconium complex onto the product obtained in step 2), followed by washing and drying. The catalyst prepared in this application is based on the hierarchical porous structure of zirconium-based MOFs. The [N,P]-type zirconium complex is loaded by in situ coordination and succinate is introduced as an electron donor, thereby forming a MOFs-metal complex-electron donor ternary synergistic catalytic system. Compared to traditional non-metallic catalysts, the catalytic performance is significantly higher.

Description

Technical Field

[0001] The present application belongs to the technical field of olefin polymerization catalysts, and in particular relates to a high-performance organic framework olefin polymerization catalyst and a preparation method thereof. Background Art

[0002] Polyolefins are a class of polymers made from alpha-olefins, which are all-carbon terminal olefins. A large portion of these alpha-olefins are used to make polyolefins, such as polyethylene and polypropylene. Polyethylene accounts for the largest share of the polyolefin production market, with the main types being high-density polyethylene, linear low-density polyethylene, and low-density polyethylene.

[0003] Early industrial production of polyethylene was achieved through free radical polymerization under high temperature and pressure, resulting in a polymer considered low-density polyethylene. Subsequently, researchers discovered that both early transition metal (titanium, zirconium, chromium) and late transition metal (iron, cobalt, nickel) catalysts can catalyze ethylene oligomerization. The catalytic effect depends largely on the coordination environment of the central metal. Therefore, current research focuses on improving catalyst activity and α-olefin selectivity by varying the central metal type and ligand structure, thereby achieving optimal molecular weight tailoring.

[0004] Currently, most industrial olefin polymerizations are carried out in heterogeneous systems. Supported catalysts are used to tailor the microstructure of synthesized macromolecules by controlling polymer chain length, molecular weight distribution, particle size, and morphology. However, common solid supports (such as SiO2 and MgCl2) do not provide a favorable platform for constructing uniformly dispersed active sites and well-defined confined spaces to tailor polymer properties and establish activity-structure relationships. Therefore, rationally designed supports, taking into account key factors such as composition, specific surface area, particle size, particle size distribution, and porosity, are crucial for regulating polymer properties in heterogeneous industrial polymerization processes.

[0005] Metal-organic frameworks (MOFs) are a class of porous materials that have emerged in recent years. They are composed of small structural units formed by metal ions and coordination groups, and organic ligands with unique properties and well-defined structures. Their structure contains three elements that can participate in catalysis: metal vertices, organic ligands, and pores. When MOFs are used as catalysts, the metal vertices on the MOFs can serve as active centers, or the functional groups present in the organic ligands can be used directly as active centers. Alternatively, the surface or pores of the MOFs can be used as a carrier or reaction site. Active sites can be loaded onto the MOF surface or pores through methods such as adsorption, impregnation, and deposition, allowing reactions to proceed on the MOF surface or within the pores, thus participating in the catalytic process.

[0006] Despite their widespread use in olefin polymerization, MOFs still face challenges. For example, the stability of MOF structures is easily affected by environmental factors such as heat, water, and oxygen, which can destroy the MOF structure. Furthermore, the catalytic activity of MOFs is masked by the metal vertices, necessitating the introduction of additional active centers. Therefore, the development of new, high-performance MOF catalysts is essential. Summary of the Invention

[0007] In view of the above problems, in order to further improve the performance of MOFs olefin polymerization catalysts, the present application provides a high-performance organic framework olefin polymerization catalyst and a preparation method thereof.

[0008] The present application first provides a method for preparing a high-performance organic framework olefin polymerization catalyst, comprising the following steps:

[0009] 1) Synthesis of zirconium-based MOFs;

[0010] 2) Impregnation of succinate into the pores of zirconium-based MOFs;

[0011] 3) Loading the [N, P] type zirconium complex on the product obtained in step 2), followed by washing and drying.

[0012] Furthermore, the step 1) includes:

[0013] 11) Synthesize UiO-66-NH2, and then react with 2-formylphenylboronic acid to prepare UiO-66-N@PBA;

[0014] 12) UiO66-N@PBA is reacted with sodium carbonate, 2-aminoethylfuran and a metal chelating agent to obtain the product.

[0015] Furthermore, in step 11), the molar ratio of UiO-66-NH2 to 2-formaldehyde phenylboronic acid is 1:(1-1.05).

[0016] Furthermore, in step 11), the specific surface area of UiO-66-NH2 is ≥1200 m² / g, and the pore size distribution is 2-5 nm.

[0017] Furthermore, in step 11), the reaction is carried out under the action of a catalyst, and the catalyst is sodium borohydride.

[0018] Furthermore, in step 12), the metal chelating agent is one or more of DTPA, DTPA derivatives, HYNIC, and HNYIC derivatives.

[0019] Furthermore, in the step 12), the chelating agent is composed of a DTPA derivative and HYNIC in a molar ratio of 1:(0.15-0.2).

[0020] Furthermore, in the step 2), the succinate is a succinate containing a phosphoric acid group.

[0021] Furthermore, in step 3), the loading rate of the [N, P] type zirconium complex is 0.5-1.2 wt %.

[0022] The present application also provides a high-performance organic framework olefin polymerization catalyst, which is prepared using the above-mentioned preparation method.

[0023] Compared with the prior art, this application has the following beneficial effects:

[0024] 1. This application constructs a hierarchical porous structure carrier based on zirconium-based MOFs, loads [N, P]-type zirconium complexes by in situ coordination, and introduces succinate as an electron donor, thereby forming a MOFs metal complex-electron donor ternary synergistic catalytic system. Compared with traditional non-metallic catalysts, the system has very high catalytic performance, and the polymerization activity, isotacticity and hydrogen regulation sensitivity are greatly improved. The olefin copolymers prepared by the catalysis have better mechanical properties such as elongation at break.

[0025] 2. This application introduces 2-formylphenylboronic acid into the zirconium-based MOF framework structure, which modifies the electron density around the boron atom and weakens the shielding effect. Furthermore, through the synergistic reaction of sodium carbonate, 2-aminoethylfuran, and a metal chelator, suitable defects and D / A cross-linking structures can be introduced into the framework system to regulate and balance the synergy and competition between chain diffusion and conformational transitions during polymerization, improve the crystallization state, and enhance catalytic properties such as polymerization activity and selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the catalytic activity data of Examples 1-3 and Control Group 1 of the present application.

[0027] Figure 2 These are the infrared spectra and XRD diffraction patterns of the catalysts of Examples 1-3 and Control Groups 1-2 of the present application.

[0028] Figure 3 TEM schematic diagrams of the catalysts of Examples 1-3 and Control Groups 1-2 of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] Among olefin polymerization catalysts, traditional Ziegler-Natta catalysts usually rely on magnesium halide supports and titanium compounds, and have problems such as insufficient stereoselectivity and poor copolymerization ability. Metallocene catalysts require the use of expensive aluminoxane co-catalysts, and the chemical inertness of the support (such as silica) leads to uneven dispersion of the active components. Although non-metallocene catalysts can achieve copolymerization of polar monomers, they have low catalytic efficiency, poor thermal stability, and a wide product molecular weight distribution. Existing organic supports for supported catalysts (such as cross-linked styrene) have low specific surface areas and cannot achieve precise control of active sites. Based on the existing technology, this application provides a high-performance organic framework olefin polymerization catalyst and a preparation method thereof after a large number of experimental studies.

[0031] Specifically, the preparation method of the high-performance organic framework olefin polymerization catalyst of the present application comprises the following steps:

[0032] 1) Synthesis of zirconium-based MOFs;

[0033] 2) Impregnation of succinate into the pores of zirconium-based MOFs;

[0034] 3) Loading the [N, P] type zirconium complex on the product obtained in step 2), followed by washing and drying.

[0035] Furthermore, the step 1) includes:

[0036] 11) Synthesize UiO-66-NH2, and then react with 2-formylphenylboronic acid to prepare UiO-66-N@PBA;

[0037] 12) UiO66-N@PBA is reacted with sodium carbonate, 2-aminoethylfuran and a metal chelating agent to obtain the product.

[0038] Furthermore, in step 11), the molar ratio of UiO-66-NH2 to 2-formaldehyde phenylboronic acid is 1:(1-1.05).

[0039] In certain specific embodiments, in step 11), the molar ratio of UiO-66-NH2 to 2-formaldehyde phenylboronic acid can be 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, or 1:1.05. Generally, in step 11), a molar ratio of UiO-66-NH2 to 2-formaldehyde phenylboronic acid of 1:1.05 achieves optimal experimental results.

[0040] Furthermore, in step 11), the specific surface area of UiO-66-NH2 is ≥1200 m² / g, and the pore size distribution is 2-5 nm.

[0041] Furthermore, in step 11), the reaction is carried out under the action of a catalyst, and the catalyst is sodium borohydride.

[0042] Furthermore, in step 12), the metal chelating agent is one or more of DTPA, DTPA derivatives, HYNIC, and HNYIC derivatives.

[0043] Furthermore, in the step 12), the chelating agent is composed of a DTPA derivative and HYNIC in a molar ratio of 1:(0.15-0.2).

[0044] In certain specific embodiments, in step 12), the chelating agent may be composed of a DTPA derivative and HYNIC in a molar ratio of 1:0.15, 1:0.155, 1:0.16, 1:0.165, 1:0.17, 1:0.175, 1:0.18, 1:0.185, 1:0.19, 1:0.195, or 1:0.2. Generally, in step 12), a chelating agent composed of a DTPA derivative and HYNIC in a molar ratio of 1:0.15 can achieve better experimental results.

[0045] Furthermore, the preparation method of the DTPA derivative comprises the following steps:

[0046] A) Diethylaminotriaminepentaacetic dianhydride, anhydrous acetic anhydride and pyridine were mixed uniformly, refluxed at 65°C, the solvent was removed by filtration, the reactant was washed with anhydrous ether, and dried to obtain product A;

[0047] B) Product A and melamine are dissolved in DMF, refluxed at 80°C, the solvent is removed, and the product is washed with acetone and dried.

[0048] Furthermore, in the step 2), the succinate is a succinate containing a phosphoric acid group.

[0049] Furthermore, in step 2), the preparation method of the succinate containing a phosphoric acid group comprises the following steps: reacting dimethyl maleate and dimethyl phosphite under the catalytic action of sodium methoxide to obtain the succinate.

[0050] Furthermore, in step 3), the loading rate of the [N, P] type zirconium complex is 0.5-1.2 wt %.

[0051] In some specific embodiments, in step 3), the loading rate of the [N,P]-type zirconium complex can be 0.5wt%, 0.55wt%, 0.6wt%, 0.65wt%, 0.7wt%, 0.75wt%, 0.8wt%, 0.85wt%, 0.9wt%, 0.95wt%, 1.0wt%, 1.05wt%, 1.1wt%, 1.15wt%, or 1.2wt%. Generally, in step 3), when the loading rate of the [N,P]-type zirconium complex is 1.05wt%, better experimental results can be obtained.

[0052] Furthermore, in step 3), the [N, P]-type zirconium complex is prepared by a method comprising the following steps: dissolving zirconium tetrachloride in dichloromethane, slowly adding dropwise an anhydrous ethanol solution containing 2-amino-5-diphenylphosphinopyridine, stirring to react, adding dropwise a small amount of potassium carbonate during the stirring process, filtering after the reaction, washing the filtrate with anhydrous ethanol, and vacuum drying to obtain the complex.

[0053] Example 1

[0054] The preparation method of the high-performance organic framework olefin polymerization catalyst of this embodiment comprises the following steps:

[0055] 1) Synthesis of zirconium-based MOFs, including:

[0056] 11) 1.0 mmol (0.233 g) of ZrCl4, 1.0 mmol (0.166 g) of TPA, and 3.6 mL of glacial acetic acid were transferred to a 50 mL high-temperature resistant Teflon liner. 30 mL of DMF was then added. The mixture was ultrasonicated for 10 min and then magnetically stirred for 1 h to mix evenly. The mixture was reacted at 120°C for 24 h. After cooling to room temperature, the mixture was alternately washed with deionized water and ethanol to remove water-soluble and alcohol-soluble impurities. After alternating washing three times, the mixture was dried in a vacuum drying oven at 80°C for 12 h and ground to obtain MOF powder.

[0057] The obtained MOF powder was added to methanol at a ratio of 1:50 in mass to volume of methanol, and activated by magnetic stirring at room temperature for 72 hours. During the stirring process, the methanol needed to be replaced every 24 hours. The upper layer of methanol was removed and fresh methanol was added to remove impurities inside the MOF pores. After activation, the MOF was centrifuged and vacuum-dried at 80°C for 12 hours. After drying, it was ground to obtain UiO-66-NH2; the specific surface area of UiO-66-NH2 was ≥1200 m² / g, and the pore size distribution was 2-5 nm.

[0058] To a 500 mL three-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, 150 mL of N,N-dimethylformamide was added, followed by 0.05 mol of UiO-66-NH2 and 0.0525 mol of 2-formylphenylboronic acid. The mixture was mixed evenly, and sodium borohydride (1% of the total mass of the reactants) was added. The mixture was heated to 85°C and stirred for 6 h. The mixture was then centrifuged and washed to obtain UiO-66-N@PBA.

[0059] 12) Dissolve 0.1 mol of sodium carbonate, 0.05 mol of 2-aminoethylfuran, and 0.1 mol of DTPA in deionized water, then add 0.05 mol of UiO66-N@PBA, stir and react at 65°C, filter, wash with deionized water, and dry in vacuum to obtain the product.

[0060] 2) Add zirconium-based MOFs to a dichloromethane solution of diethyl succinate (concentration: 0.1 mol / L) and immerse at 60°C for 24 hours with constant stirring. Ultrasonic treatment is performed every 2 hours for 15 minutes at a power of 200W to allow the diethyl succinate to fully penetrate the pores. After immersion, centrifuge and filter, wash with anhydrous ethanol, and dry.

[0061] 3) Loading the [N, P]-type zirconium complex on the product obtained in step 2) at a loading rate of 1.05 wt%, followed by washing and drying.

[0062] The [N, P]-type zirconium complex of this embodiment was prepared by a method comprising the following steps: dissolving 3.07 g of zirconium tetrachloride in 50 ml of dichloromethane, slowly adding dropwise an anhydrous ethanol solution containing 50 mmol of 2-amino-5-diphenylphosphinopyridine, stirring under nitrogen protection, adding dropwise a small amount of potassium carbonate during the stirring process, filtering after the reaction, washing the filtrate with anhydrous ethanol, and vacuum drying to obtain the product.

[0063] Example 2

[0064] The preparation method of the high-performance organic framework olefin polymerization catalyst of this embodiment comprises the following steps:

[0065] 1) Synthesis of zirconium-based MOFs, including:

[0066] 11) 1.0 mmol (0.233 g) of ZrCl4, 1.0 mmol (0.166 g) of TPA, and 3.6 mL of glacial acetic acid were transferred to a 50 mL high-temperature resistant Teflon liner. 30 mL of DMF was then added. The mixture was ultrasonicated for 10 min and then magnetically stirred for 1 h to mix evenly. The mixture was reacted at 120°C for 24 h. After cooling to room temperature, the mixture was alternately washed with deionized water and ethanol to remove water-soluble and alcohol-soluble impurities. After alternating washing three times, the mixture was dried in a vacuum drying oven at 80°C for 12 h and ground to obtain MOF powder.

[0067] The obtained MOF powder was added to methanol with a ratio of MOF powder mass to methanol volume of 1:50, and activated by magnetic stirring at room temperature for 72 h. During the stirring process, the methanol needed to be replaced every 24 h. The upper layer of methanol was removed and new methanol was added after standing for a period of time to remove impurities inside the MOF pores. After activation, the MOF was centrifuged and vacuum dried at 80°C for 12 h. After drying, it was ground to obtain UiO-66-NH2.

[0068] To a 500 mL three-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, 150 mL of N,N-dimethylformamide was added, followed by 0.05 mol of UiO-66-NH2 and 0.0525 mol of 2-formylphenylboronic acid. The mixture was mixed evenly, and sodium borohydride (1% of the total mass of the reactants) was added. The mixture was heated to 85°C and stirred for 6 h. The mixture was then centrifuged and washed to obtain UiO-66-N@PBA.

[0069] 12) Dissolve 0.1 mol of sodium carbonate, 0.05 mol of 2-aminoethylfuran, 0.087 mol of a DTPA derivative, and 0.013 mol of HYNIC in deionized water, then add 0.05 mol of UiO66-N@PBA, stir and react at 65°C, filter, wash with deionized water, and vacuum dry to obtain the DTPA derivative. The preparation method comprises the following steps:

[0070] A) 0.02 mmol of diethylaminotriaminepentaacetic dianhydride, 0.08 mmol of anhydrous acetic anhydride, and 10 mL of pyridine were placed in a three-necked flask and mixed evenly. The mixture was refluxed at 65°C for 24 h. The solvent was removed by filtration, and the reactant was washed with anhydrous ether and dried in vacuo at 80°C to obtain product A.

[0071] B) Dissolve 0.01 mol of product A and 0.02 mol of melamine in 50 mL of DMF, add 30 mL of pyridine and mix well. Reflux at 80°C for 24 h, remove the solvent by filtration, wash with acetone, and dry to obtain the product.

[0072] 2) Add zirconium-based MOFs to a dichloromethane solution of diethyl succinate (concentration: 0.1 mol / L) and immerse at 60°C for 24 hours with constant stirring. Ultrasonic treatment is performed every 2 hours for 15 minutes at a power of 200W to allow the diethyl succinate to fully penetrate the pores. After immersion, centrifuge and filter, wash with anhydrous ethanol, and dry.

[0073] 3) Loading the [N, P]-type zirconium complex on the product obtained in step 2) at a loading rate of 1.05 wt%, followed by washing and drying.

[0074] The [N, P]-type zirconium complex of this embodiment was prepared by a method comprising the following steps: dissolving 3.07 g of zirconium tetrachloride in 50 ml of dichloromethane, slowly adding dropwise an anhydrous ethanol solution containing 50 mmol of 2-amino-5-diphenylphosphinopyridine, stirring under nitrogen protection, adding dropwise a small amount of potassium carbonate during the stirring process, filtering after the reaction, washing the filtrate with anhydrous ethanol, and vacuum drying to obtain the product.

[0075] Example 3

[0076] The preparation method of the high-performance organic framework olefin polymerization catalyst of this embodiment comprises the following steps:

[0077] 1) Synthesis of zirconium-based MOFs, including:

[0078] 11) 1.0 mmol (0.233 g) of ZrCl4, 1.0 mmol (0.166 g) of TPA, and 3.6 mL of glacial acetic acid were transferred to a 50 mL high-temperature resistant Teflon liner. 30 mL of DMF was then added. The mixture was ultrasonicated for 10 min and then magnetically stirred for 1 h to mix evenly. The mixture was reacted at 120°C for 24 h. After cooling to room temperature, the mixture was alternately washed with deionized water and ethanol to remove water-soluble and alcohol-soluble impurities. After alternating washing three times, the mixture was dried in a vacuum drying oven at 80°C for 12 h and ground to obtain MOF powder.

[0079] The obtained MOF powder was added to methanol with a ratio of MOF powder mass to methanol volume of 1:50, and activated by magnetic stirring at room temperature for 72 h. During the stirring process, the methanol needed to be replaced every 24 h. The upper layer of methanol was removed and new methanol was added after standing for a period of time to remove impurities inside the MOF pores. After activation, the MOF was centrifuged and vacuum dried at 80°C for 12 h. After drying, it was ground to obtain UiO-66-NH2.

[0080] To a 500 mL three-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, 150 mL of N,N-dimethylformamide was added, followed by 0.05 mol of UiO-66-NH2 and 0.0525 mol of 2-formylphenylboronic acid. The mixture was mixed evenly, and sodium borohydride (1% of the total mass of the reactants) was added. The mixture was heated to 85°C and stirred for 6 h. The mixture was then centrifuged and washed to obtain UiO-66-N@PBA.

[0081] 12) Dissolve 0.1 mol of sodium carbonate, 0.05 mol of 2-aminoethylfuran, 0.087 mol of a DTPA derivative, and 0.013 mol of HYNIC in deionized water, then add 0.05 mol of UiO66-N@PBA, stir and react at 65°C, filter, wash with deionized water, and vacuum dry to obtain the DTPA derivative. The preparation method comprises the following steps:

[0082] A) 0.02 mmol of diethylaminotriaminepentaacetic dianhydride, 0.08 mmol of anhydrous acetic anhydride, and 10 mL of pyridine were placed in a three-necked flask and mixed evenly. The mixture was refluxed at 65°C for 24 h. The solvent was removed by filtration, and the reactant was washed with anhydrous ether and dried in vacuo at 80°C to obtain product A.

[0083] B) Dissolve 0.01 mol of product A and 0.02 mol of melamine in 50 mL of DMF, add 30 mL of pyridine and mix well. Reflux at 80°C for 24 h, remove the solvent by filtration, wash with acetone, and dry to obtain the product.

[0084] 2) Add zirconium-based MOFs to a dichloromethane solution of succinate (concentration: 0.1 mol / L) and immerse at 60°C for 24 hours with constant stirring. Ultrasonic treatment is performed every 2 hours for 15 minutes at a power of 200W to allow the diethyl succinate to fully penetrate the pores. After immersion, centrifuge and filter, wash with anhydrous ethanol, and dry.

[0085] The succinate is a succinate containing a phosphoric acid group, and the preparation method comprises the following steps: 0.1 mol of dimethyl maleate and 0.12 mol of dimethyl phosphite are placed in a reactor and mixed evenly, and then a sodium methoxide solution is slowly added dropwise, and the mixture is reacted at 25°C for 1.5 hours to obtain the obtained product;

[0086] 3) Loading the [N, P]-type zirconium complex on the product obtained in step 2) at a loading rate of 1.05 wt%, followed by washing and drying.

[0087] The [N, P]-type zirconium complex of this embodiment was prepared by a method comprising the following steps: dissolving 3.07 g of zirconium tetrachloride in 50 ml of dichloromethane, slowly adding dropwise an anhydrous ethanol solution containing 50 mmol of 2-amino-5-diphenylphosphinopyridine, stirring under nitrogen protection, adding dropwise a small amount of potassium carbonate during the stirring process, filtering after the reaction, washing the filtrate with anhydrous ethanol, and vacuum drying to obtain the product.

[0088] Control group 1

[0089] The preparation method of the olefin polymerization catalyst of this control group comprises the following steps:

[0090] 1) Synthesis of zirconium-based MOFs, including:

[0091] 1.0 mmol (0.233 g) of ZrCl4, 1.0 mmol (0.166 g) of TPA, and 3.6 mL of glacial acetic acid were transferred to a 50 mL high-temperature resistant Teflon liner, and 30 mL of DMF was added. The mixture was then ultrasonicated for 10 min and magnetically stirred for 1 h to mix evenly. The mixture was reacted at 120 ° C for 24 h. After cooling to room temperature, it was alternately washed with deionized water and ethanol to remove water-soluble and alcohol-soluble impurities. After alternating washing three times, it was placed in a vacuum drying oven and dried at 80 ° C for 12 h and ground to obtain MOF powder.

[0092] The obtained MOF powder was added to methanol at a ratio of 1:50 in mass to volume of methanol, and activated by magnetic stirring at room temperature for 72 hours. During the stirring process, the methanol needed to be replaced every 24 hours. The upper layer of methanol was removed and fresh methanol was added to remove impurities inside the MOF pores. After activation, the MOF was centrifuged and vacuum-dried at 80°C for 12 hours. After drying, it was ground to obtain UiO-66-NH2; the specific surface area of UiO-66-NH2 was ≥1200 m² / g, and the pore size distribution was 2-5 nm.

[0093] 2) Loading the [N, P]-type zirconium complex on the product obtained in step 1) at a loading rate of 1.05 wt%, followed by washing and drying.

[0094] The [N, P]-type zirconium complex of this embodiment was prepared by a method comprising the following steps: dissolving 3.07 g of zirconium tetrachloride in 50 ml of dichloromethane, slowly adding dropwise an anhydrous ethanol solution containing 50 mmol of 2-amino-5-diphenylphosphinopyridine, stirring under nitrogen protection, adding dropwise a small amount of potassium carbonate during the stirring process, filtering after the reaction, washing the filtrate with anhydrous ethanol, and vacuum drying to obtain the product.

[0095] Control group 2

[0096] The preparation method of the olefin polymerization catalyst of this control group comprises the following steps:

[0097] 1.0 mmol (0.233 g) of ZrCl4, 1.0 mmol (0.166 g) of TPA, and 3.6 mL of glacial acetic acid were transferred to a 50 mL high-temperature resistant Teflon liner, and 30 mL of DMF was added. The mixture was then ultrasonicated for 10 min and magnetically stirred for 1 h to mix evenly. The mixture was reacted at 120 ° C for 24 h. After cooling to room temperature, it was alternately washed with deionized water and ethanol to remove water-soluble and alcohol-soluble impurities. After alternating washing three times, it was placed in a vacuum drying oven and dried at 80 ° C for 12 h and ground to obtain MOF powder.

[0098] The obtained MOF powder was added to methanol with a ratio of MOF powder mass to methanol volume of 0.1:50, and activated by magnetic stirring at room temperature for 72 hours. During the stirring process, the methanol needed to be replaced every 24 hours. The upper layer of methanol was removed and new methanol was added after standing for a period of time to remove impurities inside the MOF pores. After activation, the MOF was centrifuged and vacuum-dried at 80°C for 12 hours. After drying, it was ground to obtain UiO-66-NH2, the catalyst; the specific surface area of UiO-66-NH2 was ≥1200 m² / g, and the pore size distribution was 2-5 nm.

[0099] Performance testing

[0100] 1. Ethylene polymerization performance test

[0101] A reactor with a volume of 500 mL, a maximum working pressure of 10 MPa and a maximum working temperature of 300°C was used as a polymerization device. 10 mg of the catalyst of Examples 1-3 and Control Group 1, 30 mL of toluene, and 1 mL of MAO were injected into the reactor, and then pressurized with ethylene under high-speed stirring. The reactor was kept connected to the ethylene storage tank, and the reaction was timed to end after 20 minutes. The unreacted ethylene was slowly discharged, opened to the air, and then quenched with anhydrous ethanol. The obtained suspension was transferred to a round-bottom flask using excess anhydrous ethanol, and the solvent was removed by vacuum filtration. The obtained white solid was treated with 100 mL of anhydrous ethanol and 10 mL of hydrochloric acid, and then ultrasonically treated for 30 minutes, filtered to obtain the product, and then dried in a vacuum. The performance of the processed product was analyzed by infrared spectroscopy and high-temperature gel permeation chromatography. The catalytic activity of the catalyst of Examples 1-3 and Control Group 1-2 is as shown in FIG. Figure 1 As shown. It can be seen that the ethylene polymerization catalytic activity of the catalyst of the present application can reach 8×10 6 g / (mol·h), which is more than 3 times higher than that of traditional non-cyclopentadienyl catalysts.

[0102] 2. The catalysts of Examples 1-3 and Control Groups 1-2 were subjected to infrared spectroscopy, XRD diffraction and transmission electron microscopy tests. The test results were as follows: Figure 2 、 Figure 3 As shown, it can be seen that the morphology of the catalyst changes after composite modification, which can improve the effective content and dispersion uniformity of the active center.

[0103] Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance organic framework olefin polymerization catalyst, characterized in that: The steps include: 1) Synthesizing zirconium-based MOFs; Step 1) comprises: 11) Synthesizing UiO-66-NH2, and then reacting it with 2-formylphenylboronic acid to produce UiO-66-N@PBA; the molar ratio of UiO-66-NH2 to 2-formylphenylboronic acid is 1:(1-1.05); 12) reacting UiO66-N@PBA with sodium carbonate, 2-aminoethylfuran, and a metal chelating agent to obtain the product; the metal chelating agent is one or more of DTPA, a DTPA derivative, HYNIC, and a HNYIC derivative; 2) Impregnation of succinate into the pores of zirconium-based MOFs; 3) Loading the [N, P] type zirconium complex on the product obtained in step 2), followed by washing and drying.

2. The method for preparing a high-performance organic framework olefin polymerization catalyst according to claim 1, wherein: In the step 11), the specific surface area of UiO-66-NH2 is ≥1200 m² / g, and the pore size distribution is 2-5 nm.

3. The method for preparing a high-performance organic framework olefin polymerization catalyst according to claim 1, wherein: In the step 11), the reaction is carried out under the action of a catalyst, and the catalyst is sodium borohydride.

4. The method for preparing a high-performance organic framework olefin polymerization catalyst according to claim 1, wherein: In the step 12), the chelating agent is composed of a DTPA derivative and HYNIC in a molar ratio of 1:(0.15-0.2).

5. The method for preparing a high-performance organic framework olefin polymerization catalyst according to claim 1, wherein: In the step 2), the succinate is a succinate containing a phosphoric acid group.

6. The method for preparing a high-performance organic framework olefin polymerization catalyst according to claim 1, wherein: In the step 3), the loading rate of the [N, P] type zirconium complex is 0.5-1.2 wt %.

7. A high-performance organic framework olefin polymerization catalyst, characterized by: The method is as described in any one of claims 1 to 6.

Images