Imine metal complex catalyst, preparation method thereof and application thereof in ethylene polymerization
阅读说明：本技术 亚胺类金属配合物催化剂和其制备方法及其在乙烯聚合中的应用 (Imine metal complex catalyst, preparation method thereof and application thereof in ethylene polymerization ) 是由 张文娟 郭立伟 孙文华 朱冬芝 郭晶晶 于 2019-03-20 设计创作，主要内容包括：本发明提供了亚胺类金属配合物催化剂和其制备方法及其在乙烯聚合中的应用。所述配合物具有多催化活性中心或单一的催化活性中心,可通过改变配体结构和聚合条件实现对聚合物分子量的调控,且具有催化活性高、成本低、性能稳定等优点。所述配合物可应用于乙烯聚合用催化剂中,尤其是所提供的铁配合物热稳定性高,在助催化剂作用下,其催化活性可高达到7.14×10<Sup>7</Sup>g·mol<Sup>–1</Sup>(Fe)h<Sup>–1</Sup>,得到含端基双键高度线性聚乙烯,可进一步进行官能化；即使在100℃高温时,催化活性仍然能保持在1.46×10<Sup>7</Sup>g·mol<Sup>–1</Sup>(Fe)h<Sup>–1</Sup>,符合工业生产的操作温度,具有很好的工业应用前景。(The complex has multiple catalytic activity centers or a single catalytic activity center, can realize the regulation and control of the molecular weight of a polymer by changing the ligand structure and the polymerization condition, and has the advantages of high catalytic activity, low cost, stable performance and the like 7 g·mol –1 (Fe)h –1 To obtain highly linear polyethylene containing terminal double bonds, which can be further functionalizedEven at 100 deg.c, the catalytic activity can be maintained at 1.46 × 10 7 g·mol –1 (Fe)h –1 The method meets the operation temperature of industrial production and has good industrial application prospect.)
1. An imine metal complex containing a dibenzosuberyl group, wherein the metal complex is according to formula (I):
wherein M is selected from iron, cobalt, nickel, or manganese;
each X is the same or different and is independently selected from F, Cl, Br, I, an acetonitrile group or a pyridine group;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group.
2. The metal complex of claim 1, wherein M is selected from the group consisting of iron, cobalt;
each X may be independently selected from Cl or Br;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl or C3-10A cycloalkyl group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl or C3-10A cycloalkyl group.
3. The metal complex of claim 2, wherein R is1、R2Identical or different, independently of one another, from H or C1-6An alkyl group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I or C1-6An alkyl group.
4. Process for the preparation of dibenzosuberyl-containing imine metal complexes, preferably of metal complexes according to one of claims 1 to 3, characterized in that it comprises the following steps:
reacting a compound of formula II with MX2Carrying out reaction to obtain the compound shown in the formula I,
wherein M is selected from iron, cobalt, nickel, or manganese;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group;
x is selected from F, Cl, Br, I, acetonitrile or pyridyl.
5. The method of claim 4, wherein M is selected from the group consisting of iron, cobalt;
each X may be independently selected from Cl or Br;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl or C3-10A cycloalkyl group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl or C3-10A cycloalkyl group;
preferably, the first and second electrodes are formed of a metal,
R1、R2identical or different, independently of one another, from H or C1-6An alkyl group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I or C1-6An alkyl group.
6. The preparation method according to claim 4, wherein the reaction temperature is 20-35 ℃; the reaction time is 4-24 hours; the reaction solvent is an organic solvent selected from ether, chloroalkane and alcohol, preferably one or two selected from tetrahydrofuran, dichloromethane and ethanol.
7. The method according to claim 4, further comprising reacting a compound of formula III with a corresponding aromatic amine to obtain a compound of formula II,
wherein R is1、R2Same or different, independently from each other selected from H, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group;
R3、R4、R5、R6are identical or different and are each independently selected from the group consisting of H, F, Cl, Br,I、C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group.
8. The process according to claim 7, wherein the solvent used is selected from the group consisting of toluene, xylene; the reaction temperature is 110-180 ℃; the reaction time is 4-24 h.
9. Use of a dibenzosuberyl-containing imine metalloid complex according to one of claims 1 to 3 or a dibenzosuberyl-containing imine metalloid complex prepared according to the preparation process of one of claims 4 to 7 for catalyzing olefin polymerization, preferably ethylene polymerization.
10. Use according to claim 9, wherein said dibenzosuberyl-containing imine metalloid complex is used in a catalyst composition with a cocatalyst selected from methylaluminoxane, modified methylaluminoxane, or mixtures thereof.
Technical Field
The invention relates to the field of polyolefin catalysis, in particular to a dibenzosuberyl-containing pyridine diimine metal complex, an intermediate thereof, a preparation method thereof and application thereof in catalyzing ethylene polymerization.
Background
Polyolefin resin materials are one of the most important synthetic materials, and the development thereof has a great influence on national economy of the country. Polyethylene (PE) is an important species in polyolefin resins because of its superior properties: the processing performance, the electrical insulation, the chemical stability, the high cost performance and the like are closely related to a plurality of industries such as buildings, agriculture, packaging, automobiles and the like. The yield and consumption of polyethylene in China are increased year by year, and preliminary statistics shows that the total polyethylene yield in 2016 countries all year round is 1598 ten thousand tons/year, while the yield is 1513 ten thousand tons, which is generally maintained at a relatively high level. The domestic polyethylene still has a larger supply and demand gap, and in 2020, the domestic polyethylene capacity is expected to be increased to 2100 ten thousand tons/year, and the domestic polyethylene supply capacity is greatly improved. But due to the synchronous increase of downstream demand, the domestic polyethylene demand in 2020 is expected to reach about 2920 million tons. Although the market demand and supply conditions are slightly improved, the structural contradiction is exposed while the market demand and supply conditions are developed at a high speed, namely the low-end general polyethylene material has excess capacity, and the high-end special polyethylene material still meets the demand through import. The market prospect of high-end polyethylene is optimistic, products have higher added value, but technical challenges also exist, so that the development and research of a polyethylene synthesis process are one of the hot topics of researchers.
Iron and cobalt pyridinediimine complexes, reported in succession by Brookhart et al and Gibison et al in 1998, have attracted attention from researchers (J.Am.Chem.Soc.,1998,120,4049; chem.Commun.,1998,849; J.Am.chem.Soc.,1999,121,8728) because of their ultrahigh ethylene catalytic activity, and the ability to selectively yield oligomers and highly linear polyethylenes of different molecular weights by tailoring the ligand structure, and since then reports of iron and cobalt tridentate azopyridinediimine complexes catalyzing olefin polymerization have been developed.
Although catalysts for olefin polymerization have been developed rapidly, the development thereof has not been able to satisfy the existing needs. Driven by the great demand for new polyolefin materials, the development and research and industrial development of new olefin polymerization catalysts have become a focus of attention in both academic and industrial fields. The catalyst is a key factor in the production process of polyethylene by ethylene polymerization or alpha-olefin by ethylene oligomerization. The current situation that the demand of China on the aspect of ethylene polymerization/oligomerization production is required to be changed, the improvement and the improvement of the existing catalyst are far from enough, and a new high-performance olefin polymerization catalyst needs to be designed and synthesized, so that the polymerization process is innovated. The core of developing olefin polymerization catalyst with independent intellectual property rights and polymerization technology lies in designing and synthesizing novel polyolefin catalyst model, modifying and improving the structure of the novel polyolefin catalyst model, improving catalytic activity, meeting the requirements of easy synthesis of the catalyst, low cost, high activity and high performance of polymerization products, and exploring and obtaining the novel catalyst for the polyolefin industry in China.
Disclosure of Invention
In order to solve the above problems, the present inventors have conducted intensive studies and, as a result, have found that: an imine metal complex catalyst, a preparation method thereof and application thereof in ethylene polymerization, wherein a pyridine diimine metal complex containing dibenzosuberyl is designed and synthesized and is used as a main catalyst to catalyze ethylene polymerization; the metal complex provided by the invention, particularly the iron complex and the cobalt complex, has high catalytic activity, low cost and high thermal stability, and can realize the regulation and control of the molecular weight of the polymer by changing the ligand structure and the polymerization condition, thereby completing the invention.
The object of the present invention is to provide the following:
in a first aspect, the present invention provides dibenzosuberyl-containing imine metal complexes of the type described by formula (I):
wherein M is selected from iron, cobalt, nickel, or manganese;
each X is the same or different and is independently selected from F, Cl, Br, I, an acetonitrile group or a pyridine group;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group.
In a second aspect, the present invention also provides a process for the preparation of a dibenzosuberyl-containing imine metalloid complex, preferably for use in the preparation of a metal complex according to the first aspect, said process comprising the steps of:
reacting a compound of formula II with MX2Carrying out reaction to obtain the compound shown in the formula I,
wherein, M, R1、R2、R3、R4、R5、R6X has the definition stated in formula (I) in the first aspect.
In a third aspect, the use of the metal complex of the first aspect or the metal complex prepared by the preparation method of the second aspect for catalyzing olefin polymerization, preferably ethylene polymerization.
According to the imine metal complex catalyst, the preparation method and the application thereof in ethylene polymerization, the imine metal complex catalyst has the following beneficial effects:
(1) the imine metal (iron and cobalt) complex containing dibenzosuberyl has single or multiple catalytic activity centers, can realize the regulation and control of the molecular weight and the branching degree of a polymer by changing the ligand structure and the polymerization condition, and has high catalytic activity, low cost and stable performance;
(2) the preparation method of the imine metal (iron and cobalt) complex containing dibenzosuberyl and the intermediate thereof has mild reaction conditions, short period and simple operation conditions;
(3) the imine metal (iron and cobalt) complex containing dibenzosuberyl and the application of the intermediate thereof are applied to a catalyst for ethylene polymerization, and the cobalt complex has good activity of 1.21 × 10 when catalyzing ethylene polymerization7gPE mol-1(Co)h-1The obtained polyethylene has low molecular weight and narrow distribution, and the iron complex has high catalytic activity as high as 7.14 × 107g PE mol-1(Fe)h-1. And the GPC curve of the polyethylene obtained is mostly unimodal distribution; the obtained polyethylene polymer has the characteristics of high linearity and terminal group double bonds, and has good application prospect.
Drawings
FIG. 1 shows a schematic diagram of the crystal structure of complex Co-1;
FIG. 2 shows a schematic diagram of the crystal structure of complex Co-2;
FIG. 3 shows a schematic diagram of the crystal structure of complex Co-3;
FIG. 4 shows a schematic of the crystal structure of complex Co-4;
FIG. 5 shows a schematic of the crystal structure of complex Fe-4;
FIG. 6 shows a schematic representation of the temperature-programmed nuclear magnetic carbon spectrum of the polymer obtained in example 13 i;
FIG. 7 shows a schematic representation of the elevated temperature NMR spectrum of the polymer obtained in example 17 a;
FIG. 8 shows a schematic representation of the temperature-programmed nuclear magnetic carbon spectrum of the polymer obtained in example 25 l;
FIG. 9 shows a schematic temperature-programmed NMR spectrum of a polymer obtained in example 33 k.
Detailed Description
The features and advantages of the present invention will become more apparent and appreciated from the following detailed description of the invention.
The present invention is described in detail below.
According to a first aspect of the present invention, there is provided a dibenzosuberyl-containing imine based metal complex, represented by formula I,
wherein M is selected from iron, cobalt, nickel, or manganese;
each X is the same or different and is independently selected from F, Cl, Br, I, an acetonitrile group or a pyridine group;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group.
Preferably, the first and second electrodes are formed of a metal,
m is selected from iron and cobalt;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl or C3-10A cycloalkyl group;
each X may be independently selected from Cl or Br;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl or C3-10A cycloalkyl group;
more preferably still, the first and second liquid crystal compositions are,
R1、R2identical or different, independently of one another, from H or C1-6An alkyl group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I or C1-6An alkyl group.
Still further, the compounds of formula I according to the present invention are selected from the group comprising, but not limited to, the following compounds:
compound Co-1: wherein R is1＝Me，R2＝Me，R3＝Me，R4Me, other substituents are H;
compound Co-2: wherein R is1＝Et，R2＝Et，R3＝Me，R4Me, other substituents are H;
compound Co-3: wherein R is1＝i-Pr，R2＝i-Pr，R3＝Me，R4Me, other substituents are H;
compound Co-4: wherein R is1＝Me，R2＝Et，R3＝Me，R4Me, other substituents are H;
the compound Fe-1: wherein R is1＝Me，R2＝Me，R3＝Me，R4Me, other substituents are H;
the compound Fe-2: wherein R is1＝Et，R2＝Et，R3＝Me，R4Me, other substituents are H;
the compound Fe-3: wherein R is1＝i-Pr，R2＝i-Pr，R3＝Me，R4Me, other substituents are H;
the compound Fe-4: wherein R is1＝Me，R2＝Et，R3＝Me，R4Me, other substituents are H;
in a second aspect, the present invention also provides a process for the preparation of a dibenzosuberyl-containing imine metalloid complex, preferably for use in the preparation of a metal complex according to the first aspect, said process comprising the steps of:
reacting a compound of formula II with MX2Carrying out reaction to obtain the compound shown in the formula I,
wherein R is1、R2、R3、R4、R5、R6M, X has the definition set forth in the first aspect, i.e., M is selected from iron, cobalt, nickel, or manganese; x is selected from F, Cl, Br, I, acetonitrile or pyridyl;
R1、R2same or different, independently from each other selected from H, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group;
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group.
Wherein the reaction temperature is 20-35 ℃; the reaction time is 4-24 hours; the reaction solvent is an organic solvent selected from ether, chloroalkane and alcohol, preferably one or two selected from tetrahydrofuran, dichloromethane and ethanol.
Preferably, the compound of formula (II) is reacted with FeCl2·4H2O or CoCl2Carrying out complexation reaction to obtain the iron and cobalt complex shown in the formula (I).
In the present invention, specific conditions and parameters of the complexation reaction are not particularly limited, and those skilled in the art can select specific conditions and parameters according to specific situations to prepare the target compound.
The conditions and parameters useful for the reaction are described below by way of example, and one or more of these conditions and parameters may be applied to the reaction by one skilled in the art, or may be further modified or adjusted.
Preferably, in the preparation ofProcess for preparing iron complexes of formula (I)In the process, FeCl2·4H2The charging molar ratio of O to the compound shown in the formula (II) can be 1 (1-1.5), such as 1: 1.2;
the reaction is preferably carried out in an organic solvent, for example tetrahydrofuran;
the reaction temperature can be selected within a wide range, and preferably, it can be carried out under room temperature conditions. As an example, when the solvent is tetrahydrofuran, the reaction temperature is 25 ℃;
the reaction time is 4 to 24 hours, preferably 6 to 20 hours.
After the above-mentioned complexation reaction is completed, the obtained iron complex represented by formula (I) can be further purified. The purification method may comprise the steps of:
a) pumping out the solvent of the obtained complex shown in the formula (I) by using a vacuum pump, adding an organic solvent, separating out, and dissolving in the organic solvent (such as anhydrous ether);
b) after precipitation, the solid was separated from the liquid, washed with anhydrous ether and dried.
Preferably, in the preparation ofCobalt complex process of formula (I)In (1),
CoCl2the feeding molar ratio of the compound shown in the formula (I) to the compound shown in the formula (I) can be 1 (1-1.5), such as 1: 1.2;
the reaction is preferably carried out in an organic solvent, such as a dichloromethane and ethanol system;
the reaction temperature can be selected within a wide range. Preferably, it can be carried out under room temperature conditions. As an example, when the solvent is dichloromethane, the reaction temperature is 25 ℃;
the reaction time is 4 to 24 hours, preferably 6 to 20 hours.
After the above-mentioned complexation reaction is completed, the obtained cobalt complex shown in formula (I) can be further purified. The purification method may comprise the steps of:
a') pumping out the solvent of the obtained complex shown in the formula (I) by using a vacuum pump, adding an organic solvent, precipitating, dissolving in the organic solvent (such as anhydrous ether);
b') precipitating, separating the solid from the liquid, washing the solid phase with anhydrous ether and drying.
The preparation method of the second aspect further comprises reacting the compound shown in the formula III with corresponding aromatic amine to obtain a compound shown in a formula II,
R3、R4、R5、R6identical or different, independently of one another, from H, F, Cl, Br, I, C1-6Alkyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkyl oxy, C6-14Aryl or C6-14An aryloxy group.
Wherein the solvent is selected from toluene and xylene; the reaction temperature is 110-180 ℃; the reaction time is 4-24 h.
Preferably, the solvent used is toluene;
a catalyst is also added in the reaction, and the preferred catalyst is p-toluenesulfonic acid;
in a preferred embodiment, the molar charge ratio of the compound of formula (III) to the corresponding aromatic amine compound is 1: 1.2.
In the invention, the reaction temperature is 110-180 ℃, preferably 110-160 ℃, such as 130 ℃; the condensation reaction time is 4-24 h, preferably 6-12 h, for example, 6h, 10h or 12 h.
Further, after the reaction is finished, separating the product by using an alkaline alumina chromatographic column; the separated leacheate consists of petroleum ether, ethyl acetate and triethylamine, and the volume part ratio of the petroleum ether to the ethyl acetate to the triethylamine can be 500:5: 1.
The inventors found that the molecular structures of the provided cobalt complexes Co-1, Co-2, Co-3 and Co-4 (see examples 5 to 8 for details of preparation) are respectively shown in FIGS. 1 to 4. The figure shows a penta-coordinate mode where all cobalt is formed by three nitrogen and two chlorine atoms. Wherein the complexes Co-1, Co-2, Co-4 have similar asymmetric structures due to the different orientations of the cycloheptyl groups, wherein the geometry around the central metallic cobalt in Co-1 can be described as a distorted square pyramid, with one chloride occupying the apical position and N1, N2, N3 and the other Cl2 forming a square plane. In addition, the angle formed by the two imine arms and the coordination plane is 95.2 degrees and is approximately vertical, so that the active center is protected. Co-2, Co-4 have a structure similar to Co-1, where cobalt is coordinated by 3 nitrogens and 2 chlorines, and the geometry around cobalt can be described as a distorted square pyramid, with the dibenzosuberyl ring para to the aniline all in a boat configuration, and the structure of Co-1, Co-2, Co-4 is asymmetric due to the different orientation of the dibenzosuberyl rings. In contrast, although Co-3 has a coordination pattern similar to that of the other analogs, the geometry around the cobalt is a trigonal bipyramid, unlike the geometry of Co-1, Co-2, Co-4, but the structure of Co-3 is symmetrical due to the same orientation of its dibenzosuberyl group in the para-position of the aniline.
The inventors also found that the iron complex Fe-4 provided by the invention (see example 12 for details of preparation) has a penta-coordination structure, as shown in FIG. 5. Wherein the iron center is surrounded by three nitrogen atoms belonging to the group of 2,6- (bisarylimino) pyridines and two chlorine atoms, the structure of which is a distorted tetragonal pyramid geometry. The nitrogen atoms (N1, N2 and N3) and the chlorine atoms (Cl1) form basal planes, Cl (2) is located in the axial position, and the Cl (2) -Fe (1) distance is 2.2547 (8). Distances of N (1) -Fe (1), N (3) -Fe (1) and Cl (1) -Fe (1) were almost similar (2.201(1), 2.213(2), and) But are respectively larger than the distance N (2) -Fe (1)Indicating a stronger coordination bond between the nitrogen in the pyridine ring and the central iron metal. The angle formed by the imine and the coordination plane is 83.5 degrees and is approximately vertical, which is beneficial to protecting the active center of iron.
In a third aspect, the present invention also provides the use of the dibenzosuberyl-containing imine metalloid complex of the first aspect or the dibenzosuberyl-containing imine metalloid complex prepared according to the preparation method of the second aspect, for catalyzing olefin polymerization, preferably ethylene polymerization. The resulting ethylene polymer is a highly linear polyethylene containing terminal double bonds.
Further, the dibenzosuberyl-containing imine metal complex is used in a catalyst composition with a cocatalyst selected from methylaluminoxane, modified methylaluminoxane, or a mixture thereof.
Namely, the invention further provides a catalyst composition, which comprises a main catalyst and an optional cocatalyst, wherein the main catalyst is selected from one or more metal complexes shown in the formula (I), and preferably one or two of iron and cobalt complexes.
According to the present invention, the catalyst composition is used for the polymerization of olefins, preferably for the polymerization of ethylene.
According to the present invention, the cocatalyst is selected from one or more of aluminoxane, alkylaluminum, and alkylaluminum chloride.
According to the invention, the cocatalyst may be selected from methylaluminoxane (MAO for short), modified methylaluminoxane (MMAO for short) or mixtures thereof; the Modified Methylaluminoxane (MMAO) is commercially available from various publicly available sources, such as Akzo Nobel, USA.
When the catalyst composition further comprises a cocatalyst, and M in the compound shown in the formula I is selected from Fe, the molar ratio of metal Al in the cocatalyst to Fe in the compound shown in the formula I is 1000-3000: 1, such as 1000:1, 1500:1, 2000:1, 2500:1, 2750:1 and 3000: 1;
preferably, when the cocatalyst is Methylaluminoxane (MAO), the molar ratio of metal Al in the Methylaluminoxane (MAO) to Fe in the compound shown in the formula (I) is (1000-3000): 1, and preferably the molar ratio is 2750: 1;
preferably, when the cocatalyst is Modified Methylaluminoxane (MMAO), the molar ratio of metal Al in the Modified Methylaluminoxane (MMAO) to Fe in the complex shown in the formula (I) is (1000-3000): 1, and the preferred molar ratio is 2000: 1.
When the catalyst composition further comprises a cocatalyst, and M in the compound shown in the formula I is selected from Co, the molar ratio of the metal Al in the cocatalyst to the Co in the compound shown in the formula I is 1000-3000: 1, such as 1000:1, 1500:1, 2000:1, 2250:1, 2500:1, 2750:1 or 3000: 1;
preferably, when the cocatalyst is Methylaluminoxane (MAO), the molar ratio of metal Al in the Methylaluminoxane (MAO) to Co in the compound shown in the formula (I) is (1000-3000): 1, and preferably is 2500: 1;
preferably, when the cocatalyst is Modified Methylaluminoxane (MMAO), the molar ratio of the metal Al in the Modified Methylaluminoxane (MMAO) to the Co in the compound shown in the formula (I) is (1000-3000): 1, and the preferred molar ratio is 2000: 1.
In a fourth aspect, the present invention also provides a process for preparing polyethylene, comprising the steps of: ethylene is polymerized under the catalysis of the catalyst composition as described above to obtain polyethylene.
According to the invention, the temperature of the polymerization reaction is 0 to 100 ℃, for example 20 to 100 ℃, such as 20 ℃,40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃;
according to the invention, the pressure of the polymerization reaction is 1-10 atm;
according to the invention, the polymerization time is between 5min and 60min, for example 30 min;
according to the invention, the polymerization reaction can be carried out in a solvent; the solvent is selected from one or more of alcohol solvents, alkane solvents, aromatic solvents and the like, for example, one or more selected from toluene, isobutanol and n-hexane, such as toluene.
The complex provided by the invention has multiple catalytic activity centers or a single catalytic activity center, can realize the regulation and control of the molecular weight of the polymer by changing the ligand structure and the polymerization condition, and has the advantages of high catalytic activity, low cost, stable performance and the like. The complexes can be used in ethyleneIn the catalyst for polymerization, the provided iron complex has high thermal stability, and the catalytic activity can reach 7.14 × 10 under the action of a cocatalyst7g·mol–1(Fe)h–1The obtained highly linear polyethylene containing terminal double bonds can be further functionalized, and the catalytic activity can still be maintained at 1.46 × 10 even at the high temperature of 100 DEG C7g·mol–1(Fe)h–1。
Term definition and interpretation
The term "C1-6Alkyl "is understood to mean a linear or branched, saturated monovalent hydrocarbon radical having 1,2, 3, 4, 5 or 6 carbon atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-ethylpropyl, 1, 2-dimethylpropyl, neopentyl, 1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3-dimethylbutyl, 2-dimethylbutyl, 1-dimethylbutyl, 2, 3-dimethylbutyl, 1, 3-dimethylbutyl or 1, 2-dimethylbutyl or isomers thereof. In particular, the radicals have 1,2, 3 or 4 carbon atoms ("C)1-4Alkyl groups) such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, tert-butyl, more particularly groups having 1,2 or 3 carbon atoms ("C)1-3Alkyl groups) such as methyl, ethyl, n-propyl or isopropyl.
The term "C3-10Cycloalkyl "is understood to mean a saturated monovalent monocyclic or bicyclic hydrocarbon ring having 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Said C is3-10Cycloalkyl groups may be monocyclic hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl, or bicyclic hydrocarbon groups such as decalin rings.
The term "C6-14Aryl "is to be understood as preferably meaning a mono-, bi-or tricyclic hydrocarbon ring having a monovalent or partially aromatic character with 6, 7, 8, 9, 10, 11, 12, 13 or 14 carbon atoms (" C6-14Aryl "), in particularIs a ring having 6 carbon atoms (' C)6Aryl "), such as phenyl; or biphenyl, or is a ring having 9 carbon atoms ("C9Aryl), such as indanyl or indenyl, or a ring having 10 carbon atoms ("C10Aryl radicals), such as tetralinyl, dihydronaphthyl or naphthyl, or rings having 13 carbon atoms ("C13Aryl radicals), such as the fluorenyl radical, or a ring having 14 carbon atoms ("C)14Aryl), such as anthracenyl.
The term "halogen" includes F, Cl, Br, I.