WO2025232102A1 - Olefin polymerization catalyst and preparation method therefor, and olefin polymerization method - Google Patents

Abstract

The present invention relates to the technical field of chemical synthesis, and in particular to an olefin polymerization catalyst and a preparation method therefor, and an olefin polymerization method. The catalyst comprises a cationic pyridylamine-based hafnium (Hf) active component having a structure represented by formula (1), and a modified SiO₂ carrier, wherein the modified SiO₂ carrier comprises an SiO₂ matrix, and an anionic boron (B) compound having a structure represented by formula (2); B in the anionic B compound is connected to at least part of O on the surface of the SiO₂ matrix; and on the basis of the total weight of the catalyst, in the catalyst, the content of Hf on an elemental basis is 1-5 wt%, the content of B on an elemental basis is 0.2-0.8 mmol/g, and the content of Si on an elemental basis is 25-60 wt%. The catalytic polymerization activity is high, the stability is good, and the problems of "runaway polymerization", poor morphology of polymerization products, and difficulty in continuous production in homogeneous catalyst systems can be effectively solved.

Description

Olefin polymerization catalysts and their preparation methods, methods for olefin polymerization

Cross-reference to related applications

This application claims the benefit of Chinese Patent Application No. 202410570737.0, filed on May 9, 2024, entitled "Olefin Polymerization Catalyst and Preparation Method Thereof, Method for Olefin Polymerization", the contents of which are incorporated herein by reference.

Technical Field

This invention relates to the field of chemical synthesis technology, specifically to an olefin polymerization catalyst and its preparation method, as well as a method for olefin polymerization.

Background Technology

Poly(4-methyl-1-pentene) (PMP) is a crystalline resin with a stereoregular structure. This unique structure endows it with excellent properties, including superior chemical resistance, mechanical properties, and processability; excellent electrical insulation properties; low dielectric properties; optical properties; air permeability; and easy peeling properties. Therefore, this type of high-end thermoplastic resin has important applications in fiber materials, release materials, high-end medical materials, and electronic materials. It is particularly suitable for insulators for 5G and 6G communication high-frequency devices, pharmaceutical sustained-release membranes, ECMO membranes, and other advanced network communication, microporous materials, and high-end medical fields. The demand for PMP products is expected to grow rapidly.

4-Methyl-1-pentene monomers have a unique structure with long side chains and an isopropyl group at the end, making them one of the most sterically hindered monomers among commonly used olefin monomers, exhibiting a strong steric hindrance effect. Therefore, conventionally used high-activity polyolefin catalysts show very low activity for the polymerization of 4-methyl-1-pentene, with slow coordination and insertion rates. For example, metallocene catalysts, due to their single metal center, result in a narrow molecular weight distribution of polymerized polyolefins (PMPs), typically below 3. The large steric hindrance of metallocene catalysts makes it difficult for the sterically hindered 4-methyl-1-pentene monomer to insert, resulting in low catalytic activity for 4-methyl-1-pentene, more than 10 times lower than that of Ziegler-Natta catalysts. In contrast, non-metallocene catalysts lack ring-fixing properties, have a more open steric environment, and can achieve chirality of the metal center through racemic mixing and selective optimization of skeletal substituents, balancing high activity and isotacticity. This has led to increasing interest in non-metallocene catalysts.

Pyridine-amine hafnium catalysts were discovered in 2003 by Dow Chemical and Symyx using high-throughput screening. These catalysts exhibit superior catalytic performance in olefin polymerization, demonstrating excellent stereoselectivity. They can catalyze the polymerization of propylene and other α-olefins at high temperatures to prepare highly isotactic polyolefin materials. Furthermore, these catalysts also possess good copolymerization properties, capable of catalyzing the copolymerization of ethylene, propylene, and α-olefins to prepare polyolefin materials with high α-olefin insertion rates. Therefore, pyridine-amine hafnium catalysts have received widespread attention in the polyolefin field.

Currently, pyridine-amine hafnium catalysts are mainly used for homogeneous solution polymerization, and can be used for the highly active solution polymerization of 4-methyl-1-pentene. However, the production of PMP resin using pyridine-amine hafnium catalysts in solution polymerization processes faces a series of problems. For example, "explosive polymerization" is prone to occur, the morphology of the polymerization product is poor, the reactor is prone to scaling, the separation of product and catalyst is difficult, and continuous production is difficult to achieve.

To address the aforementioned issues, the pyridine-amine hafnium catalyst can be supported to allow the monomers to be directionally polymerized into regular spherical particles. By coordinating the catalyst and polymerization process conditions, the overall viscosity of the polymerization system can be controlled to ensure that the product performance meets the required specifications. At the same time, continuous gas-phase and slurry polymerization can be achieved by controlling the polymer morphology and preventing reactor contamination. Professor Marks's research group at Northwestern University conducted research on the supported pyridine-amine hafnium catalyst (Marks et al. ACS Catal. 2021, 11, 3239-3250; Marks et al. ACS Catal. 2018, 8, 4893-4901.). They supported pyridine-amine hafnium complexes on alumina sulfate (AlS) and zirconium sulfate (ZrS) to study the homopolymerization of ethylene and the copolymerization of ethylene and 1-octene. However, the activity of this supported pyridine-amine hafnium catalyst was greatly reduced. The highest catalytic activity in olefin polymerization was only 4.8 × ^10⁴ gpolymer/(mol Hf·h), which cannot meet the industrial requirements for catalyst activity.

Therefore, developing an olefin polymerization catalyst with high activity, excellent reaction stability, good product morphology, and the ability to achieve continuous production is of great significance and plays a driving role in the industrialization of polyolefins.

Summary of the Invention

This invention addresses the problems of existing homogeneous pyridine-amine-based hafnium catalysts in the production of polyolefins, such as reactor scaling, difficulty in separating products and catalysts, difficulty in achieving continuous production, and poor product morphology, as well as the problem of existing supported pyridine-amine-based hafnium catalysts having low activity and failing to meet application requirements. The invention provides an olefin polymerization catalyst, its preparation method, and a method for olefin polymerization.

To achieve the above objectives, a first aspect of the present invention provides an olefin polymerization catalyst comprising a cationic pyridineamine hafnium active component with the structure shown in formula (1) and a modified _SiO2 support; wherein the modified _SiO2 support comprises a _SiO2 matrix and an anionic boron compound with the structure shown in formula (2); wherein the B in the anionic boron compound is connected to at least a portion of the O on the surface of the _SiO2 matrix;

In formula (1), _R1 , _R2 , _R3 , _R4 , _R5 , _R6 , R7, _R8 , _R9 , _R10 , _R11 , _R12 , _R13 , _R14 , and _R15 are each independently selected from -H or C1 _{- C9} hydrocarbon groups; _R16 and _R17 are each independently selected from -H or C1 _{- C9} hydrocarbon groups, and when _{R16 and R17} are each independently C2 _{- C6} alkyl groups, they can close into a ring.

Based on the total weight of the catalyst, the catalyst contains 1-5 wt% Hf, 0.2-0.8 wt% B, and 25-60 wt% Si.

A second aspect of the present invention provides a method for preparing an olefin polymerization catalyst, comprising:

(1) The _SiO2 particles were activated to obtain an activated support;

(2) In the presence of a first solvent, the activated support is reacted with B( _C6F5 ) ₃ to obtain a first product; then the first product is reacted with an ionizing agent to obtain a _SiO2- supported ion _- paired boron compound.

(3) In the presence of a second solvent, the pyridine-amine hafnium complex with the structure shown in formula (1') is subjected to an ion exchange reaction with the _SiO2 -supported ion-paired boron compound to obtain an olefin polymerization catalyst.

Among them, _R1 , _R2 , _R3 , _R4 , _R5 , _R6 , _R7 , _R8 , R9, _R10 , _R11 , _R12 , _R13 , _R14 , and _R15 are each independently selected from -H or C1 _{- C9} hydrocarbon groups; _{R16 and R17} are each independently selected from -H or C1 _{- C9} hydrocarbon groups, and when _R16 and _R17 are each independently C2 _{- C6} alkyl groups, they can close to form a ring;

The weight ratio _{of the activated support to B(C6F5)3 is 1} :(0.3-1); the molar ratio of the ionizing reagent to B( _C6F5 ) ₃ is ( _1-2 ):1; and the molar ratio of Hf: _SiO2 -loaded ions in the pyridineamine hafnium complex to B in the boron compound is (0.6-1.6):1.

The third aspect of the present invention provides an olefin polymerization catalyst prepared by the preparation method described in the second aspect above.

A fourth aspect of the present invention provides a method for olefin polymerization, comprising: polymerizing an olefin monomer in the presence of a main catalyst and an optional co-catalyst to obtain a polymerization product;

The main catalyst is the olefin polymerization catalyst described in the first or third aspect above.

The olefin polymerization catalyst provided by this invention has the following beneficial effects:

(1) The olefin polymerization catalyst provided by the present invention has high catalytic polymerization activity. Compared with the existing reported pyridine-amine hafnium catalysts supported on alumina sulfate (AlS) or zirconium sulfate (ZrS), the catalyst provided by the present invention has significantly improved activity and has good industrialization prospects.

(2) The components of the olefin polymerization catalyst provided by the present invention are bonded by chemical bonds (Si-O covalent bonds, B-O covalent bonds and Hf-B ionic bonds). Compared with the catalyst prepared by simple blend adsorption, it has better stability, and the olefin polymerization reaction is stable and efficient. It can effectively solve the problems of "explosive polymerization", poor morphology of polymerization products and difficulty in continuous production in homogeneous catalyst systems.

(3) The preparation process is simple, the preparation cost is low, and the economic benefits are good.

Attached Figure Description

Figure 1 is a morphology diagram of poly(4-methyl-1-pentene) prepared using the catalyst prepared in Example 1 of the present invention.

Figure 2 shows the morphology of poly(4-methyl-1-pentene) prepared using the catalyst prepared in Comparative Example 4 of the present invention.

Detailed Implementation

The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

The first aspect of the present invention provides an olefin polymerization catalyst, the catalyst comprising a cationic pyridineamine hafnium active component with the structure shown in formula (1), and a modified _SiO2 support; wherein the modified _SiO2 support comprises a _SiO2 matrix and an anionic boron compound with the structure shown in formula (2); the B in the anionic boron compound is connected to at least a portion of the O on the surface of the _SiO2 matrix;

In formula (1), _R1 , _R2 , _R3 , _R4 , _R5 , _R6 , R7, _R8 , _R9 , _R10 , _R11 , _R12 , _R13 , _R14 , and _R15 are each independently selected from -H or C1 _{- C9} hydrocarbon groups; _R16 and _R17 are each independently selected from -H or C1 _{- C9} hydrocarbon groups, and when _{R16 and R17} are each independently C2 _{- C6} alkyl groups, they can close into a ring.

Based on the total weight of the catalyst, the catalyst contains 1-5 wt% Hf, 0.2-0.8 wt% B, and 25-60 wt% Si.

The catalyst provided by this invention is a novel supported pyridine-amine hafnium olefin polymerization catalyst with a specific structure. The bonding relationship between the cationic pyridine-amine hafnium active component and the modified _SiO2 support is shown in Equation (7). It should be explained and emphasized by the inventor that Equation (7) is only used to illustrate the structure of the catalyst and the bonding relationship between the components, and does not represent the quantitative relationship between the components. As can be seen from equation (7), on the one hand, the cationic pyridineamine hafnium active component (hafnium metal center) in this catalyst is "free" outside the modified _SiO2 support, which can effectively reduce the activity loss caused by loading and help maintain the high polymerization activity of the catalyst; on the other hand, the matrix of the modified _SiO2 support in this catalyst is connected to the anionic boron compound through chemical bonds, which has better stability and allows the modified _SiO2 support to have a higher boron content, enabling it to load more hafnium metal centers. Moreover, the anionic boron compound can act on the hafnium metal center over a long distance through ionic bonds, ensuring that the polymerization can proceed smoothly and continuously without the "explosive polymerization" problem of the homogeneous catalyst system. The polymerization product has a good morphology and a narrow product particle size distribution. This catalyst can be used for the homopolymerization or copolymerization of various olefin monomers, and can especially meet the requirements of solution polymerization process for PMP for catalyst activity and stability.

According to the present invention, the cationic pyridineamine hafnium active component represented by formula (1) provides the hafnium metal center of the olefin polymerization catalyst. In formula (1), preferably, _R1 , _R2 , _R3 , R4, _R5 , _R6 , _R7 , _R8 , _R9 , _R10 , _R11 , _R12 , _R13 , _R14 , _{and R15} are each independently selected from -H or C1 _{- C4} hydrocarbon groups, which makes the cationic pyridineamine hafnium active component have less steric hindrance, which is more conducive to the insertion of comonomers during the polymerization reaction and obtains high catalytic activity.

According to a preferred embodiment of the present invention, in the olefin polymerization catalyst, the cationic pyridine-amine hafnium active component has the structure shown in formula (3) or formula (4), which can make the olefin polymerization catalyst have higher catalytic activity. More preferably, the cationic pyridine-amine hafnium active component has the structure shown in formula (4).

According to the present invention, in the olefin polymerization catalyst, in formula (2), This indicates the connection site between the anionic boron compound and at least a portion of the O on the surface of the _SiO2 matrix.

According to the present invention, in the olefin polymerization catalyst, the Hf content, B content, and Si content (based on the elemental basis) preferably, based on the total weight of the catalyst, are 4-5 wt% Hf content, 0.6-0.8 wt% B content, and 25-30 wt% Si content, respectively, thereby enabling the olefin polymerization catalyst to have further improved catalytic activity.

In this invention, the elemental content in the catalyst is determined according to the method specified in GB/T 30902-2014 and using ICP (inductively coupled plasma spectrometry).

According to a preferred embodiment of the present invention, the olefin polymerization catalyst comprises a cationic pyridinamine hafnium active component with the structure shown in formula (4) and a modified _SiO2 support; wherein the modified _SiO2 support comprises a _SiO2 matrix and an anionic boron compound with the structure shown in formula (2); the B in the anionic boron compound is connected to at least a portion of the O on the surface of the _SiO2 matrix; based on the total weight of the catalyst, the catalyst contains 4.7-5 wt% Hf, 0.6-0.75 wt% B, and 25-27 wt% Si. The catalyst of the above preferred embodiment has better overall performance by balancing high polymerization activity, excellent stability, and good morphology of the polymerization product.

A second aspect of the present invention provides a method for preparing an olefin polymerization catalyst, comprising:

(1) The _SiO2 particles were activated to obtain an activated support;

(2) In the presence of a first solvent, the activated support is reacted with B( _C6F5 ) ₃ to obtain a first product; then the first product is reacted with an ionizing agent to obtain a _SiO2- supported ion _- paired boron compound.

(3) In the presence of a second solvent, the pyridine-amine hafnium complex with the structure shown in formula (1') is subjected to an ion exchange reaction with the _SiO2 -supported ion-paired boron compound to obtain an olefin polymerization catalyst;

Among them, _R1 , _R2 , _R3 , _R4 , _R5 , _R6 , _R7 , _R8 , R9, _R10 , _R11 , _R12 , _R13 , _R14 , and _R15 are each independently selected from -H or C1 _{- C9} hydrocarbon groups; _{R16 and R17} are each independently selected from -H or C1 _{- C9} hydrocarbon groups, and when _R16 and _R17 are each independently C2 _{- C6} alkyl groups, they can close to form a ring;

The weight ratio _{of the activated support to B(C6F5)3 is 1} :(0.3-1); the molar ratio of the ionizing reagent to B( _C6F5 ) ₃ is ( _1-2 ):1; and the molar ratio of Hf: _SiO2 -loaded ions in the pyridineamine hafnium complex to B in the boron compound is (0.6-1.6):1.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (1), the _SiO2 particles can be any self-made or commercially available _SiO2 particles that can be used as a catalyst support. Preferably, the average particle size of the _SiO2 particles is 20-200 μm, which is beneficial to the olefin polymerization of the obtained catalyst. The catalyst was used to prepare polymer products with low fine powder content and uniform particle size distribution in the catalytic polymerization of olefin monomers.

In this invention, the average particle size refers to D50, which can be determined using a laser particle size analyzer according to the method specified in GB/T 41949-2022.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (1), the activation treatment can be carried out by heating the _SiO2 particles. Preferably, the activation treatment conditions include: a temperature of 200-700℃ and a time of 1-10h.

According to a preferred embodiment of the present invention, the activation treatment includes: placing the _SiO2 particles in a heating device, heating them to 200-250°C at a heating rate of 1-5°C/min, holding the temperature for 0.5-2 hours, and then heating them to 500-700°C at a heating rate of 1-5°C/min, holding the temperature for 2-6 hours to obtain an activated carrier.

According to the present invention, in the preparation method of the olefin polymerization catalyst, the _SiO2 particles are activated to form isolated silanol groups on the surface of the _SiO2 particles so that they can be chemically bonded to the boron atoms in B( _C6F5 ) ₃ in step (2).

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (1), the content of silanol groups in the activated support is 0.5-2 mmol/g, preferably 1-1.5 mmol/g, which is conducive to the forward reaction of the activated support and B( _C6F5 ) ₃ in step (2) and promotes the formation of BO bonds.

In this invention, the content of silanol groups can be determined by nuclear magnetic resonance hydrogen spectroscopy.

According to the present invention, in the preparation method of the olefin polymerization catalyst, step (2) has a relatively broad limitation on the first solvent, as long as it can dissolve B( _C6F5 ) ₃ . Preferably, the first solvent can be selected from at least one of toluene, n-pentane, n-hexane, cyclohexane, and n-heptane, _which is beneficial to the dissolution _of B( _C6F5 ) ₃ and the dispersion of the activated support. The first solvent can be further preferably toluene and/or n-heptane.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (2), for the first reaction, preferably, under a protective atmosphere, the activated support is first mixed with the first solvent to obtain a mixed slurry, and then the mixed slurry is mixed with B( _C6F5 ) ₃ to undergo the first reaction. Preferably, the conditions for the first reaction include: _a temperature of 0-50°C and a time of 1-12 h.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (2), the amount of the first solvent used is relatively limited, as long as it can fully dissolve the above- _mentioned amount of B( _C6F5 ) _3. Preferably, the weight ratio of the activated support to the first solvent is 1:(15-25), which is more conducive to the dissolution _of B( _C6F5 ) ₃ and the uniform dispersion of the activated support.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (2), for the second reaction, preferably, the product system (first product) obtained from the first reaction is mixed with the ionizing reagent and a second reaction occurs. Preferably, the conditions for the second reaction include: the reaction is carried out under light-protected conditions, the temperature is 0-50°C, and the time is 6-24 hours.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (2), preferably, the ionizing agent can be selected from _CPh3Cl and/or _NPhMe2 , which can promote the forward shift of the reversible reaction of BO bonding and form a more stable BO bond. The ionizing agent is further preferably _CPh3Cl .

According to the present invention, preferably, the ionizing agent is added in the form of a solution. For example, the ionizing agent is pre-prepared with an organic solvent to form a solution with a concentration of 0.5-1 mol/L. Preferably, the organic solvent may be selected from at least one of toluene, xylene, and ethylbenzene.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (2), a _SiO2 -supported ion-pair boron compound (support) is prepared by sequentially performing the first reaction and the second reaction. Specifically, when the ionizing agent is _CPh3Cl , the main reaction process in step (2) is illustrated as follows:

When the ionizing reagent is _NPhMe2 , the main reaction process in step (2) is shown below:

In this invention, the preparation method of the _SiO2- supported _ion -pair boron compound differs from the direct mixing method. The direct mixing method involves simply dissolving and mixing the raw materials in solution, with the _SiO2 support and B( _C6F5 ) ₃ primarily undergoing physical adsorption. This results in a low boron content in the prepared support, significantly reducing the loading of the active component and decreasing the catalyst activity. In contrast, this invention prepares the _SiO2 -supported _ion -pair boron compound through a chemical reaction. The _SiO2 support and B( _C6F5 ) ₃ are bonded by chemical bonds, which significantly increases the boron content in the support and also improves the stability of the O and B atom bond, making it more favorable for the subsequent loading of pyridine-amine hafnium complexes onto the support.

According to the present invention, in the preparation method of the olefin polymerization catalyst, preferably, the content of B in the _SiO2- supported ion-pair boron compound is 0.2-0.8 mmol/g, which is more conducive to the loading of the pyridine-amine hafnium complex on the support in step (3).

In this invention, the content of B in the carrier is determined according to the method specified in GB/T 30902-2014 and using ICP (inductively coupled plasma spectrometry).

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (3), the second solvent is an aromatic hydrocarbon solvent, preferably at least one of benzene, toluene and ethylbenzene.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (3), for the ion exchange reaction, preferably, under a protective atmosphere, the pyridine-amine hafnium complex is first mixed with the second solvent, and then the _SiO2 -supported ion-paired boron compound is added to mix and undergo an ion exchange reaction to obtain a solid. The solid is then purified to obtain the olefin polymerization catalyst. Preferably, the conditions for the ion exchange reaction include: a temperature of 0-50°C and a time of 0.5-5 h.

According to the present invention, in the preparation method of the olefin polymerization catalyst, the amount of the second agent used in step (3) is relatively limited, as long as it can fully dissolve the pyridine-amine hafnium complex. Preferably, the weight ratio of the pyridine-amine hafnium complex to the second solvent is 1:(20-60).

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (3), a cationic pyridine amino-based hafnium active component and a boron compound supported on _SiO2 to counteract the anion (containing anionic boron compound) are generated through the ion exchange reaction. The main reaction process is illustrated below:

In the prepared catalyst, the cationic pyridine-amine hafnium active component (hafnium metal center) is "free" outside the modified _SiO2 support, which can effectively reduce the activity loss caused by loading and help maintain the high polymerization activity of the catalyst. In addition, the anionic boron compound can act on the hafnium metal center over a long distance through ionic bonds, ensuring that the polymerization can proceed smoothly and continuously without the "explosive polymerization" problem of the homogeneous catalyst system. The polymerization product has good morphology and a narrow product particle size distribution.

According to the present invention, in the preparation method of the olefin polymerization catalyst, in step (3), preferably, the pyridine-amine hafnium complex has the structure shown in formula (5) or formula (6), which enables the prepared olefin polymerization catalyst to have higher catalytic activity. More preferably, the pyridine-amine hafnium complex has the structure shown in formula (6).

According to the present invention, in the preparation method of the olefin polymerization catalyst, the feed amounts of each raw material _, while satisfying the above-mentioned limitations, preferably have the following characteristics: the weight ratio of the activated support to B( _C6F5 ) ₃ is 1:(0.6-1); the molar ratio of the ionizing reagent to B( _C6F5 ) ₃ is ( _1.1-1.5 ):1; and the molar ratio of Hf in the pyridine-amine hafnium complex to B in the boron compound supported by _SiO2 is (1-1.6):1. This allows the prepared catalyst to have better comprehensive performance in terms of high polymerization activity, excellent stability, and good morphology of the polymerization product.

The third aspect of the present invention provides an olefin polymerization catalyst prepared by the preparation method described in the second aspect above.

According to the present invention, the catalyst prepared by the method described in the second aspect above has the same structure, composition and performance as the olefin polymerization catalyst described in the first aspect above, and will not be repeated here.

A fourth aspect of the present invention provides a method for olefin polymerization, comprising: polymerizing an olefin monomer in the presence of a main catalyst and an optional co-catalyst to obtain a polymerization product;

The main catalyst is the olefin polymerization catalyst described in the first or third aspect above.

According to the present invention, the method for olefin polymerization has a broad definition of the olefin monomer, and preferably can be selected from at least one of 4-methyl-1-pentene, ethylene, propylene, 1-butene, 1-hexene and 1-octene.

According to the present invention, in the method for olefin polymerization, the olefin polymerization catalyst can catalyze olefin polymerization with or without a co-catalyst, exhibiting high activity. In the present invention, the co-catalyst can be an organoaluminum compound, including but not limited to triisobutylaluminum, triethylaluminum, tri-n-hexylaluminum, trimethylaluminum, diethylaluminum chloride, etc., preferably triisobutylaluminum. Preferably, the molar ratio of Al in the organoaluminum compound to Hf in the olefin polymerization catalyst is (0-200):1.

According to the present invention, in the method of olefin polymerization, the polymerization reaction is preferably carried out by gas-phase polymerization or slurry polymerization.

The olefin polymerization method provided by this invention can catalyze olefin polymerization with high activity, the reaction process is stable, which is conducive to continuous production, and the polymerization product has good morphology and a narrow particle size distribution. In particular, this method can solve the problems of insufficient reactivity, unstable reaction, and difficulty in continuous production in the preparation of PMP by existing solution polymerization processes.

The present invention will be described in detail below through examples. Unless otherwise specified, the preparation examples, embodiments and comparative examples described below are all conventional methods; unless otherwise specified, the reagents and materials are all commercially available.

In the following preparation examples and embodiments, the molar ratio of the initiator G and the structural units contained in the polymer was calculated by the amount of raw materials fed.

Preparation Example 1

This preparation example illustrates the preparation of pyridineamine-based hafnium complexes.

The pyridine-amine hafnium complex (denoted as Hf-1) was prepared according to the method described in the literature (Gregory J Domski, James M Eagan, Claudio De Rosa, et al. Combined Experimental and Theoretical Approach for Living and Isoselective Propylene Polymerization[J].ACS Catal.2017,7,6930-6937). Hf-1 has the structure shown in formula (4).

HF-1 was subjected to 1H NMR spectroscopy, and the obtained 1H NMR spectrum is as follows: ^¹H NMR ( _C₆D₆ , _400MHz ): δ (ppm) δ 8.42 (d, 1H, Ar-H), 7.46-7.40 (m, 2H, Ar-H), 7.23-6.72 (m, 10H, Ar-H), 6.36 (d, 1H, Ar-H), 5.92 (s, 1H, NCH), 3.80 (sept, 1H, CH( _CH₃ ) _₂ ), 3.22 (sept, 1H, CH( _CH₃ ) _₂ ), 2.91 (sept, 1H, CH( _CH₃ ) _₂ ), 1.38 (d, 6H, CH( _CH₃ ) _₂ ), 1.13-1.15 (d, 6H, CH ₍ CH₃) _₂ ). ),0.94(s,3H,Hf-CH ₃ ),0.71(d,3H,CH(CH ₃ ) ₂ ),0.63(s,3H,Hf-CH ₃ ),0.38(d,3H,CH(CH ₃ ) ₂ ).

Preparation Example 2

This preparation example illustrates the preparation of pyridineamine-based hafnium complexes.

The pyridine-amine hafnium complex (denoted as Hf-2) was prepared according to the method in the literature (Gregory J Domski, James M Eagan, Claudio De Rosa, et al. Combined Experimental and Theoretical Approach for Living and Isoselective Propylene Polymerization[J].ACS Catal.2017,7,6930-6937). Hf-2 has the structure shown in formula (3).

HF-2 was subjected to 1H NMR spectroscopy, and the obtained 1H NMR spectrum is as follows: ^¹H NMR ( _C₆D₆ , _400MHz ): δ (ppm) 8.59 (d, 1H, Nap-H), 8.25 (d, 1H, Nap-H), 7.82 (d, 1H, Nap-H), 7.71 (d, 1H, Nap-H), 7.50 (d, 1H, Py-H), 7.35-7.00 (m, 9H, Ar-H), 6.83 (d, 1H, Py-H), 6.56 (s, 1H, NCH), 6.55 (d, 1H, Py-H), 3.84 (sept, 1H, CH( _CH₃ ) _₂ ), 3.34 (sept, 1H, CH( _CH₃ ) _₂ ), 2.90 (sept, 1H, CH( _CH₃ ) _₂ ). ),1.38(d,3H,CH(CH ₃ ) ₂ ),1.36(d,3H,CH(CH ₃ ) ₂ ),1.18(d,3H,CH(CH ₃ ) ₂ ),1.15(d,3H,CH(CH ₃ ) ₂ ),0.95(s,3H,Hf-CH ₃ ),0.70(d,3H,CH(CH ₃ ) ₂ ), 0.68(s,3H,Hf-CH ₃ ), 0.39(d,3H,CH(CH ₃ ) ₂ ).

Preparation Example 3

This preparation example illustrates the preparation of the activated support.

10g of _SiO2 particles (average particle size of 50μm) were placed in a tube furnace and heated from 25℃ to 200℃ at a heating rate of 2.9℃/min, held at that temperature for 1h, and then heated to 600℃ at a heating rate of 4.4℃/min, held at that temperature for 4h to obtain the activated support (denoted as Z-1).

Determination of Si-OH content on the surface of activated support Z-1: 100 mg of the above-mentioned activated support was weighed into a sealed NMR tube under nitrogen protection, 0.5 mL _{of C6D6} (without TMS) was added, followed by 20 mg of ferrocene as an internal standard, and finally 10 mg _{of LiCH2SiMe3} was added. After reacting at 25 °C for 1 h, ¹ H NMR was performed. Based on the relative integral area of the generated tetramethylsilane, the surface silanol content of activated support Z-1 was calculated to be 2.0 mmol/g.

Preparation Example 4

10g of _SiO2 particles (average particle size of 50μm) were placed in a tube furnace and heated from 25℃ to 210℃ at a heating rate of 2.3℃/min, held at that temperature for 1.5h, and then heated to 500℃ at a heating rate of 5℃/min, held at that temperature for 2h to obtain the activated support (denoted as Z-2).

Determination of Si-OH content on the surface of activated support Z-2: 100 mg of the above-mentioned activated support was weighed into a sealed NMR tube under nitrogen protection, 0.5 mL _{of C6D6} (without TMS) was added, followed by 20 mg of ferrocene as an internal standard, and finally 10 mg _{of LiCH2SiMe3} was added. After reacting at 25 °C for 1 h, ¹ H NMR was performed. Based on the relative integral area of the generated tetramethylsilane, the surface silanol content of activated support Z-2 was calculated to be 0.5 mmol/g.

Preparation Example 5

This preparation example illustrates the preparation of _SiO2 -supported ion-pair boron compounds.

Under a nitrogen atmosphere, the activated support Z-1 (1 g) prepared in Preparation Example 3 was dispersed in 20 mL of anhydrous toluene solvent to obtain a mixed slurry; then B( _C6F5 ) ₃ (0.6 g, 1.17 mmol) was added, and the mixture was stirred at ₂₅ °C for 4 h to carry out the first reaction, obtaining the first product; the ionizing reagent _CPh3Cl (0.42 g, 1.52 mmol) was dissolved in 2 mL of toluene and added to the first product, and the mixture was stirred at 25 °C in the dark for 12 h to carry out the second reaction. After the reaction was completed, the mixture was filtered through a sintered glass filter, washed three times with anhydrous toluene (3 × 10 mL), and dried under vacuum for 6 h to obtain the _SiO2 -supported ion-pair boron compound (denoted as S-1).

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was performed on S-1, and the B content in S-1 was found to be 0.64 mmol/g.

Preparation Examples 6-7

This preparation example illustrates the preparation of _SiO2 -supported ion-pair boron compounds.

The method of Preparation Example 5 was followed, except that in Preparation Example 6, the activated support Z-1 (1g) obtained in Preparation Example 3 was dispersed in 20mL of anhydrous n-pentane solvent to obtain a mixed slurry. The conditions of the first reaction were adjusted (temperature was 0℃, reaction time was 12h), and the conditions of the second reaction were adjusted (temperature was 0℃, reaction time was 24h). All other steps and conditions were the same as in Preparation 5, and _SiO2 -supported ion-pair boron compound (denoted as S-2) was obtained.

The method of Preparation Example 5 was followed, except that in Preparation Example 7, the activated support Z-2 (1g) obtained in Preparation Example 4 was dispersed in 20mL of anhydrous n-heptane solvent to obtain a mixed slurry, and the conditions of the first reaction were adjusted (temperature 50°C, reaction time 1h), and the conditions of the second reaction were adjusted. The conditions (temperature 50℃, reaction time 6h) were the same as those in preparation 5, and other steps and conditions were the same to obtain the _SiO2 -supported ion-pair boron compound (denoted as S-3).

The main preparation conditions of S-2 and S-3 and the B content (ICP-AES) of S-2 and S-3 are shown in Table 1.

Preparation Examples 8-9

This preparation example illustrates the preparation of _SiO2 -supported ion-pair boron compounds.

The method of Preparation Example 5 was followed, except that in Preparation Example ₈ , the weight ratio of B( _C6F5 ) ₃ to the activated support was 0.3:1, and the other steps and conditions were the same as in Preparation 5, to obtain the _SiO2 -supported ion-pair boron compound (denoted as S-4).

The method of Preparation Example 5 was followed, except that in Preparation Example ₉ , the weight ratio of B( _C6F5 ) ₃ to the activated support was 1:1, and the other steps and conditions were the same as in Preparation 5, to obtain the _SiO2 -supported ion-pair boron compound (denoted as S-5).

The main preparation conditions of S-4 and S-5 and the B content (ICP-AES) of S-4 and S-5 are shown in Table 1.

Preparation Example 10

This preparation example illustrates the preparation of _SiO2 -supported ion-pair boron compounds.

Following the method of Preparation Example 5, the only difference was that the ionizing reagent _CPh3Cl was replaced with an equimolar amount of _NPhMe2 , while the other steps and conditions were the same as in Preparation 5, to obtain the _SiO2- supported ion-pair boron compound (denoted as S-6).

The main preparation conditions of S-6 and the B content of S-6 (ICP-AES) are shown in Table 1.

Preparation Examples 11-12

This preparation example illustrates the preparation of _SiO2 -supported ion-pair boron compounds.

The method of Preparation Example 5 was followed, except that in Preparation Example 11, the molar ratio _{of the ionizing reagent to B(C6F5)3 was 1} :1, and the other steps and conditions were the same as in Preparation 5, to obtain the _SiO2 -supported ion-pair boron compound (denoted as S-7).

The method of Preparation Example 5 was followed, except that in Preparation Example 12, the molar ratio of the ionizing reagent to B( _C6F5 ) ₃ was 2:1, and the other steps and conditions were the same as in Preparation 5, to obtain the _SiO2 -supported _ion -pair boron compound (denoted as S-8).

The main preparation conditions of S-7 and S-8 and the B content (ICP-AES) of S-7 and S-8 are shown in Table 1.

Table 1

Example 1

This example illustrates the preparation of the catalyst.

Under a nitrogen atmosphere, the pyridine-amine hafnium complex Hf-2 (0.46 g, 0.64 mmol) and dry toluene solvent (20 mL) were mixed together in a 100 mL Schlenk reaction flask. Then, the _SiO2- supported ion-pair boron compound S-1 (1 g) prepared above was added, and the reaction was stirred at 25 °C for 2 h. After the reaction was completed, the mixture was filtered through a sintered glass filter, washed three times with anhydrous toluene (3 × 10 mL), and dried under vacuum for 6 h. The resulting solid was the olefin polymerization catalyst (denoted as Cat-1).

ICP-AES testing was performed on Cat-1, and the Hf content, B content, and Si content in Cat-1 (based on elemental composition) were measured and are shown in Table 2.

Example 2

This example illustrates the preparation of the catalyst.

The method of Example 1 was followed, except that the pyridine-amine hafnium complex Hf-2 was replaced with an equimolar amount of Hf-1, and all other steps and conditions were the same as in Example 1, to obtain the olefin polymerization catalyst (denoted as Cat-2).

ICP-AES testing was performed on Cat-2, and the Hf content, B content, and Si content in Cat-2 (based on elemental composition) were measured and are shown in Table 2.

Examples 3-9

This example illustrates the preparation of the catalyst.

The method of Example 1 was followed, except that the _SiO2 -supported ion-pair boron compound S-1 was replaced with equimolar amounts of S-2, S-3, S-4, S-5, S-6, S-7, and S-8, respectively. All other steps and conditions were the same as in Example 1, to obtain olefin polymerization catalysts (denoted as Cat-3, Cat-4, Cat-5, Cat-6, Cat-7, Cat-8, and Cat-9, respectively).

ICP-AES tests were performed on Cat-3, Cat-4, Cat-5, Cat-6, Cat-7, Cat-8, and Cat-9. The Hf content, B content, and Si content (in elemental terms) were obtained and are shown in Table 2.

Example 10

This example illustrates the preparation of the catalyst.

The method of Example 1 was followed, except that the molar ratio of Hf:B of the pyridine-amine hafnium complex Hf- ₂ and the SiO2-supported ion-pair boron compound S-1 was 0.6:1. All other steps and conditions were the same as in Example 1, and an olefin polymerization catalyst (denoted as Cat-10) was obtained.

The ICP-AES test was performed on Cat-10, and the Hf content, B content, and Si content (in elemental terms) were obtained, as shown in Table 2.

Example 11

This example illustrates the preparation of the catalyst.

The method of Example 1 was followed, except that the molar ratio of Hf:B of the pyridineamine hafnium complex Hf-2 and the _SiO2- supported ion-pair boron compound S-1 was 1.6:1. All other steps and conditions were the same as in Example 1, and an olefin polymerization catalyst (denoted as Cat-11) was obtained.

The ICP-AES test was performed on Cat-11, and the Hf content, B content, and Si content (in elemental terms) were obtained, as shown in Table 2.

Example 12

This example illustrates the preparation of the catalyst.

Following the method of Example 1, the only difference being that the reaction temperature was 0°C and the reaction time was 0.5 h, while all other steps and conditions were the same as in Example 1, to obtain an olefin polymerization catalyst (denoted as Cat-12).

ICP-AES testing was performed on Cat-12, and the Hf content, B content, and Si content (in elemental terms) were obtained, as shown in Table 2.

Example 13

This example illustrates the preparation of the catalyst.

Following the method of Example 1, the only difference being that the reaction temperature was 50°C and the reaction time was 5 hours, while all other steps and conditions were the same as in Example 1, to obtain an olefin polymerization catalyst (denoted as Cat-13).

The ICP-AES test was performed on Cat-13, and the Hf content, B content, and Si content (in elemental terms) were obtained, as shown in Table 2.

Comparative Example 1

This comparative example illustrates the preparation of catalysts.

The above-mentioned pyridine-amine hafnium complex Hf-2 was directly used as an olefin polymerization catalyst (denoted as D-Cat-1).

Comparative Example 2

This comparative example illustrates the preparation of catalysts.

The boron compound supported on _SiO2 was prepared by direct mixing method: Under a nitrogen atmosphere, the above-mentioned activated support (1g) was dispersed in 20mL of anhydrous toluene solvent and mixed into a slurry. Then, 1.17mmol of [ _Ph3C ][ _B ( _C6F5 ) ₄ ] was added, and the mixture was directly stirred at 25℃ for 12h. The mixture was filtered through a sand filter ball, washed three times with anhydrous toluene (3×10mL), and vacuum dried for 6h to obtain the boron compound supported on _SiO2 prepared by direct mixing method.

Take ₁ g of the boron compound supported on SiO2 prepared above, 0.46 g of the above pyridine-amino hafnium complex Hf-2 (0.64 mmol), and dried... The toluene solvent (20 mL) was mixed together with the reaction mixture in a 100 mL Schlenk reaction flask. The mixture was stirred and reacted directly at 25 °C for 2 h. After the reaction was completed, the mixture was filtered through a sintered glass filter ball, washed three times with anhydrous toluene (3 × 10 mL), and dried under vacuum for 6 h to obtain the _SiO2 supported hafnium catalyst (denoted as D-Cat-2) prepared by the direct mixing method.

ICP-AES testing was performed on D-Cat-2, and the Hf content and B content (in terms of elemental composition) were obtained, as shown in Table 2.

Comparative Example 3

This comparative example illustrates the preparation of catalysts.

Under a nitrogen atmosphere, pyridine-amine hafnium complex Hf-2 (0.46 g, 0.64 mmol) and dry toluene solvent (20 mL) were mixed together in a 100 mL Schlenk reaction flask. Then, the _SiO2- supported ion-pair boron compound S-1 (1 g) prepared above was added, and the reaction was stirred at 25 °C for 0.2 h. After the reaction was completed, the mixture was filtered through a sintered glass filter, washed three times with anhydrous toluene (3 × 10 mL), and dried under vacuum for 6 h to obtain the olefin polymerization catalyst (denoted as D-Cat-3).

ICP-AES testing was performed on D-Cat-3, and the Hf content and B content (in terms of elemental composition) were obtained, as shown in Table 2.

Comparative Example 4

This example illustrates the preparation of the catalyst.

2 μmol of pyridineamine hafnium compound Hf-2 and 2.4 μmol of triphenylcarbium tetra(pentafluorophenyl)borate (Hf:B molar ratio of 1:1.2) were mixed in 2 mL of toluene and reacted to obtain an olefin polymerization catalyst (denoted as D-Cat-4).

ICP-AES testing was performed on D-Cat-4, and the Hf content and B content (in terms of elemental composition) were obtained, as shown in Table 2.

Table 2

Test case

1. Catalytic homopolymerization test of 4-methyl-1-pentene

Homopolymerization of 4-methyl-1-pentene was carried out using the catalysts Cat-1, Cat-2, Cat-3, Cat-4, Cat-5, Cat-6, Cat-7, Cat-8, Cat-9, Cat-10, Cat-11, Cat-12, Cat-13, D-Cat-1, D-Cat-2, D-Cat-3, and D-Cat-4, respectively. The test procedures and conditions are as follows:

Under anhydrous and oxygen-free conditions, 6 mL of dry toluene, 3 mL of 4-methyl-1-pentene, and 0.2 mmol of triisobutylaluminum were added to a reaction flask. 8 mg of the above catalyst (Al:Hf molar ratio shown in Table 3) was dispersed in 1 mL of toluene and added to the reaction flask using a syringe. The reaction was carried out at 50 °C. The polymerization was terminated with an ethanol solution acidified with 10% hydrochloric acid for 20 min. After stirring for 2 h, the mixture was filtered, washed three times with ethanol, and dried in a vacuum drying oven at 60 °C for 12 h to obtain the PMP polymer product.

The catalyst activity in the above reactions, as well as the molecular weight distribution, weight-average molecular weight and particle size (D50) of the obtained PMP polymer products were tested respectively. The results are shown in Table 3.

Table 3

Note: In Table 3, the molar ratio of Al:Hf refers to the molar ratio of Hf in the catalyst to Al in triisobutylaluminum; the polymer products prepared by tests 1-13, 15-16 and 18-19 are spherical particles in appearance.

2. Catalytic homopolymerization test of other olefin monomers

(2-1) Catalytic homopolymerization test of propylene monomer

Propylene was subjected to homopolymerization using the catalysts Cat-1, D-Cat-1, D-Cat-2, D-Cat-3, and D-Cat-4, respectively. The test procedures and conditions are as follows:

Under anhydrous and oxygen-free conditions, 98 mL of dry toluene and 0.5 mmol of triisobutylaluminum were added to the reactor. 20 mg of the above catalyst was dispersed in 2 mL of toluene and added to the reactor using a syringe. Propylene was introduced at 10 atm, and the homopolymerization of propylene was carried out at 50 °C for 20 min. The polymerization was terminated with an ethanol solution acidified with 10% hydrochloric acid. After stirring for 2 h, the mixture was filtered, washed three times with ethanol, and dried in a vacuum drying oven at 60 °C for 12 h to obtain the linear polyethylene product.

The catalyst activity in the above reactions, as well as the melting temperature, weight-average molecular weight, molecular weight distribution, and particle size (D50) of the obtained linear polyethylene products were tested. The results are shown in Table 4.

(2-2) Catalytic homopolymerization test of 1-butene monomer

Following the methods and parameters in the above (2-1) catalytic homopolymerization test of propylene monomer, the difference is that the monomer being polymerized is 1-butene, resulting in polybutene product;

The catalyst activity in the above reaction was tested, as well as the melting temperature, weight-average molecular weight, molecular weight distribution and particle size (D50) of the obtained polybutene product. The results are shown in Table 4.

(2-3) Catalytic homopolymerization test of ethylene monomer

The method and parameters in the above (2-1) catalytic homopolymerization test of propylene monomer are the same, except that the monomer used for polymerization is ethylene, and polyethylene product is obtained.

The catalyst activity in the above reactions, as well as the melting temperature, weight-average molecular weight, molecular weight distribution, and particle size (D50) of the obtained polyethylene products were tested respectively. The results are shown in Table 4.

(2-4) Catalytic homopolymerization test of 1-hexene monomer

Under anhydrous and oxygen-free conditions, 6 mL of dry toluene, 3 mL of 1-hexene, and 0.2 mmol of triisobutylaluminum were added to a reaction flask. 8 mg of catalyst Cat-1 (the molar ratio of Hf in Cat-1 to Al in triisobutylaluminum was 100:1) was dispersed in 1 mL of toluene and added to the reaction flask using a syringe. The reaction was carried out at 50 °C for 20 min. The polymerization was terminated with an ethanol solution acidified with 10% hydrochloric acid. After stirring for 2 h, the mixture was filtered, washed three times with ethanol, and dried in a vacuum drying oven at 60 °C for 12 h to obtain the polyhexene product.

The catalyst activity in the above reaction was tested, as well as the melting temperature, weight-average molecular weight, molecular weight distribution and particle size (D50) of the obtained polyethylene product. The results are shown in Table 4.

(2-5) Catalytic homopolymerization test of 1-octene monomer

Under anhydrous and oxygen-free conditions, 6 mL of dry toluene, 3 mL of 1-octene, and 0.2 mmol of triisobutylaluminum were added to a reaction flask. 8 mg of catalyst Cat-1 (the molar ratio of Hf in Cat-1 to Al in triisobutylaluminum was 100:1) was dispersed in 1 mL of toluene and added to the reaction flask using a syringe. The reaction was carried out at 50 °C for 20 min. The polymerization was terminated with an ethanol solution acidified with 10% hydrochloric acid. After stirring for 2 h, the mixture was filtered, washed three times with ethanol, and dried in a vacuum drying oven at 60 °C for 12 h to obtain the polyoctene product.

The catalyst activity in the above reactions, as well as the melting temperature, weight-average molecular weight, molecular weight distribution and particle size (D50) of the obtained polyoctene products were tested respectively. The results are shown in Table 4.

Table 4

As shown in Tables 3 and 4, the olefin polymerization catalyst provided by this invention can catalyze the polymerization reaction of various olefin monomers with high activity. The product D50 is between 22-31 μm (under the condition that the molar ratio of Al:Hf is 100), and the molecular weight distribution of the product is relatively narrow. Compared with the supported catalyst prepared by conventional mixing method, this catalyst has a larger loading of active centers and higher catalytic activity, and can prepare polyolefin products with higher molecular weight. Compared with homogeneous unsupported catalyst, this catalyst can produce spherical polyolefin powders with better morphology (Figure 1 shows the morphology of poly4-methyl-1-pentene obtained in Test 1 above, the product is spherical and the particle size is relatively uniform; Figure 2 shows the morphology of poly4-methyl-1-pentene obtained in Test 17 above, the product after reaction is a viscous liquid, and after drying, the product is in blocks of different sizes). It can effectively solve the problems of polymer sticking and clogging, meet the needs of continuous production of polyolefins, and is especially suitable for gas phase process and slurry polymerization process.

The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims (21)

An olefin polymerization catalyst, characterized in that the catalyst comprises a cationic pyridineamine hafnium active component with the structure shown in formula (1) and a modified _SiO2 support; wherein the modified _SiO2 support comprises a _SiO2 matrix and an anionic boron compound with the structure shown in formula (2); the B in the anionic boron compound is connected to at least a portion of the O on the surface of the _SiO2 matrix.
In formula (1), _R1 , _R2 , _R3 , _R4 , _R5 , _R6 , R7, _R8 , _R9 , _R10 , _R11 , _R12 , _R13 , _R14 , and _R15 are each independently selected from -H or _C1 - _C9 hydrocarbon groups; _R16 and _R17 are each independently selected from -H or _C1 - _C9 hydrocarbon groups, and when _{R16 and R17} are each independently _C2 - _C6 alkyl groups, they can close to form a ring. Based on the total weight of the catalyst, the catalyst contains 1-5 wt% Hf, 0.2-0.8 mmol/g B, and 25-60 wt% Si. According to claim 1, in formula (1), _R1 , R2, _R3 , _R4 , _R5 , _R6 , _R7 , _R8 , R9, _R10 , _R11 , _R12 , _{R13 , R14} , _{and R15} are each independently selected from -H or _C1 - _C4 hydrocarbon groups. According to claim 2, the catalyst wherein the cationic pyridine-amino-hafnium active component has the structure shown in formula (3) or formula (4);
According to any one of claims 1-3, the method wherein, based on the total weight of the catalyst, the catalyst contains 4-5 wt% Hf, 0.6-0.8 mmol/g B, and 25-30 wt% Si. A method for preparing an olefin polymerization catalyst, comprising: (1) The _SiO2 particles were activated to obtain an activated support; (2) In the presence of a first solvent, the activated support is reacted with B( _C6F5 ) ₃ to obtain a first product; then the first product is reacted with an ionizing agent to obtain a _SiO2- supported ion _- paired boron compound. (3) In the presence of a second solvent, the pyridine-amine hafnium complex with the structure shown in formula (1') is subjected to an ion exchange reaction with the _SiO2 -supported ion-paired boron compound to obtain an olefin polymerization catalyst.
Among them, _R1 , _R2 , _R3 , _R4 , _R5 , _R6 , _R7 , _R8 , R9, _R10 , _R11 , _R12 , _R13 , _R14 , and _R15 are each independently selected from -H or _C1 - _C9 hydrocarbon groups; _{R16 and R17} are each independently selected from -H or _C1 - _C9 hydrocarbon groups, and when _R16 and _R17 are each independently _C2 - _C6 alkyl groups, they can close to form a ring; The weight ratio _{of the activated support to B(C6F5)3 is 1} :(0.3-1); the molar ratio of the ionizing reagent to B( _C6F5 ) ₃ is ( _1-2 ):1; and the molar ratio of Hf: _SiO2 -loaded ions in the pyridineamine hafnium complex to B in the boron compound is (0.6-1.6):1. According to the method of claim 5, in step (1), the average particle size of the _SiO2 particles is 20-200 μm. According to the method of claim 5 or 6, in step (1), the activation treatment conditions include: a temperature of 200-700℃ and a time of 1-10h. According to the method of claim 7, in step (1), the content of silanol groups in the activated carrier is 0.5-2 mmol/g. According to the method of claim 5 or 6, in step (2), the first solvent is selected from at least one of toluene, n-pentane, n-hexane, cyclohexane, and n-heptane. According to the method of claim 5 or 6, in step (2), the conditions for the first reaction include: a temperature of 0-50°C and a time of 1-12h. According to the method of claim 5 or 6, in step (2), the ionizing agent is selected from _CPh3Cl and/or NPhMe. According to the method of claim 5 or 6, in step (2), the conditions for the second reaction include: the reaction is carried out under light-protected conditions, the temperature is 0-50°C, and the time is 6-24h. According to the method of claim 12, in step (2), the content of B in the _SiO2- supported ion-pair boron compound is 0.2-0.8 mmol/g. According to the method of claim 5 or 6, in step (3), the second solvent is an aromatic hydrocarbon solvent. According to the method of claim 5 or 6, in step (3), the conditions for the ion exchange reaction include: a temperature of 0-50°C and a time of 0.5-5h. According to the method of claim 15, in step (3), the pyridineamine hafnium complex has the structure shown in formula (5) or formula (6);
The olefin polymerization catalyst prepared by the preparation method according to any one of claims 5-16. A method for olefin polymerization includes: polymerizing olefin monomers in the presence of a main catalyst and an optional co-catalyst to obtain a polymerization product; The main catalyst is the olefin polymerization catalyst according to any one of claims 1-4 and 17. According to the method of claim 18, the olefin monomer is selected from at least one of 4-methyl-1-pentene, ethylene, propylene, 1-butene, 1-hexene, and 1-octene. According to the method of claim 18, the co-catalyst is an organoaluminum compound. The method according to any one of claims 18-20, wherein the polymerization reaction is carried out by gas-phase polymerization or slurry polymerization.