NNP-tridentate metal complex catalyst as well as preparation method and application thereof

Abstract

The invention discloses an NNP-tridentate metal complex catalyst, the structure of the NNP-tridentate metal complex catalyst is shown as a formula I: # imgabs0 #, R is selected from one of substituted or non-substituted alkane, substituted or non-substituted cycloalkane, substituted or non-substituted hetero-cycloalkane, substituted or non-substituted aryl and substituted or non-substituted hetero-aryl, and R is selected from one of substituted or non-substituted alkyl, substituted or non-substituted cycloalkane, substituted or non-substituted hetero-aryl, substituted or non-substituted aryl and substituted or non-substituted hetero-aryl; m is selected from Cr, Mo and rare earth metal. The invention also discloses a method for preparing the NNP-tridentate metal complex catalyst, an application of the NNP-tridentate metal complex catalyst in ethylene polymerization, and an ethylene polymerization method. According to the NNP-tridentate metal complex catalyst provided by the invention, the weight-average molecular weight of polyethylene can be well regulated and controlled by adjusting the ratio of the cocatalyst to the NNP-tridentate metal complex, so that low-molecular-weight polyethylene wax and high-molecular-weight polyethylene engineering plastic are prepared.

Description

Technical Field

[0001] The invention relates to the field of catalysts for olefin polymerization, and in particular to an NNP-tridentate metal complex catalyst and a one-pot preparation method thereof and application thereof in ethylene polymerization. Background Art

[0002] Polyolefins have become the most productive synthetic polymers, and the core of their technological development is catalysts. Low molecular weight polyethylene can be used as wax and lubricant additives, while ultra-high molecular weight polyethylene is a typical engineering polymer. Usually, different catalysts are used to prepare different polyethylenes, but their design and synthesis are expensive and the route is long. Therefore, catalyzing the polymerization of ethylene through different catalytic systems is a very good method. Phillips chromium catalyst (CrO x / SiO2) is one of the most critical catalysts in industry. Although Phillips chromium catalysts have been studied for more than 70 years, their initiation process, the coordination environment and oxidation state of the active substance with the metal, and the catalytic mechanism remain to be studied, so people have turned their research to homogeneous chromium catalysts, which can be studied by various spectra. In particular, multidentate ligands containing N, O, S and / or P donor atoms can better control the metal coordination number, and the catalytic performance can be improved by fine-tuning their structure. These catalysts catalyze ethylene polymerization to obtain products ranging from low molecular weight polyethylene wax to UHMWPE engineering plastics. Therefore, finding new ligand-loaded metal chromium complexes is still crucial for new polyolefin homogeneous catalysts. Summary of the invention

[0003] Based on the above, the purpose of the present invention is to provide a NNP-tridentate metal complex catalyst having both nitrogen and phosphorus ligands, which is particularly suitable for catalyzing ethylene polymerization, and can well regulate the molecular weight of polyethylene in the cooperation of a co-catalyst to prepare low molecular weight polyethylene wax and high molecular weight polyethylene engineering plastics; the purpose of the present invention is also to provide a method for preparing the NNP-tridentate metal complex catalyst simply, cheaply and efficiently.

[0004] To achieve the above objectives, in a first aspect, the present invention provides a NNP-tridentate metal complex catalyst, wherein the structure of the NNP-tridentate metal complex is as shown in Formula I:

[0005]

[0006] Wherein, R is selected from one of substituted or unsubstituted chain alkane groups, substituted or unsubstituted cycloalkane groups, substituted or unsubstituted heterocycloalkane groups, substituted or unsubstituted aromatic groups, and substituted or unsubstituted heteroaromatic groups; and M is selected from Cr, Mo and rare earth metals.

[0007] As a specific embodiment of the present invention, preferably, the substituent in the substituted alkane group, substituted cycloalkane group, substituted heterocycloalkane group, substituted aromatic group and substituted heteroaromatic group is selected from methyl group or phenyl group.

[0008] As a specific embodiment of the present invention, preferably, R is selected from one of substituted or unsubstituted C1-20 chain alkane groups, substituted or unsubstituted C3-20 cycloalkane groups, substituted or unsubstituted C2-20 heterocycloalkane groups, substituted or unsubstituted C6-20 aromatic groups, substituted or unsubstituted C5-20 heteroaromatic groups, wherein the heteroatom is selected from at least one of N, O, and S; further preferably, R is selected from one of substituted or unsubstituted C1-10 chain alkane groups, substituted or unsubstituted C3-10 cycloalkane groups, substituted or unsubstituted C2-10 heterocycloalkane groups, substituted or unsubstituted C6-10 aromatic groups, substituted or unsubstituted C5-10 heteroaromatic groups; further preferably, R is selected from one of methyl, ethyl, phenyl, or tolyl.

[0009] To achieve the above object, in a second aspect, the present invention provides a method for preparing the above NNP-tridentate metal complex catalyst, comprising the following steps:

[0010] (1) mixing a metal M compound with an organic solvent to obtain a metal solution;

[0011] (2) dissolving the NNP-tridentate organic ligand in the organic solvent, and then adding NaH in an amount equimolar to the NNP-tridentate organic ligand to react;

[0012] (3) adding the reaction mixture obtained in step (2) dropwise into the metal solution to react and obtain a NNP-tridentate metal complex.

[0013] As a specific embodiment of the present invention, preferably, the structure of the NNP-tridentate organic ligand is as shown in Formula II:

[0014]

[0015] wherein R is selected from a substituted or unsubstituted alkane substituent, a substituted or unsubstituted cycloalkane substituent, a substituted or unsubstituted heterocycloalkane substituent, a substituted or unsubstituted aromatic group, and a substituted or unsubstituted heteroaromatic group; more preferably, R is selected from a substituted or unsubstituted C1-20 alkane substituent, a substituted or unsubstituted C3-20 cycloalkane substituent, a substituted or unsubstituted C2-20 heterocycloalkane substituent, a substituted or unsubstituted C6-20 aromatic group, and a substituted or unsubstituted C5-20 heteroaromatic group, wherein the heteroatom is selected from at least one of N, O, and S; further preferably, R is selected from a substituted or unsubstituted C1-10 alkane substituent, a substituted or unsubstituted C3-10 cycloalkane substituent, a substituted or unsubstituted C2-10 heterocycloalkane substituent, a substituted or unsubstituted C6-10 aromatic group, and a substituted or unsubstituted C5-10 heteroaromatic group; further preferably, R is selected from a methyl group, an ethyl group, a phenyl group, or a tolyl group;

[0016] And / or, the metal M compound is selected from at least one of chromium chloride, molybdenum chloride, scandium chloride, yttrium chloride, lanthanum chloride and cerium chloride, and further preferably, the metal M compound is an anhydrous metal M compound;

[0017] And / or, the organic solvent is selected from at least one of dioxane, chloroform, n-hexane, n-heptane, benzene, toluene, cyclohexane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, trichlorobenzene and tetrahydrofuran, more preferably toluene.

[0018] As a specific embodiment of the present invention, preferably, the method of the above-mentioned NNP-tridentate metal complex catalyst of the present invention specifically comprises the following steps:

[0019]

[0020] NNP-tridentate organic ligand (structure of formula (I), M is Cr) and anhydrous chromium trichloride are used as raw materials, NaH is used as a base, and after the reaction is completed, a NNP-tridentate metal complex is obtained.

[0021] To achieve the above objectives, in a third aspect, the present invention provides an application of the above-mentioned NNP-tridentate metal complex catalyst or the NNP-tridentate metal complex catalyst obtained by the above-mentioned method in ethylene polymerization, preferably, the ethylene polymerization is ethylene homopolymerization.

[0022] To achieve the above object, in a fourth aspect, the present invention provides a method for ethylene polymerization, comprising the following steps:

[0023] S1, adding the above-mentioned NNP-tridentate metal complex or the NNP-tridentate metal complex prepared by the above-mentioned method into a reaction vessel, then introducing ethylene gas, and then adding a co-catalyst to polymerize ethylene;

[0024] S2, stop feeding ethylene, and add a terminator to the reaction mixture obtained in step S1;

[0025] S3. Pour the reaction mixture obtained in step S2 into a detergent, and then filter, wash and dry to obtain polyethylene.

[0026] As a specific embodiment of the present invention, preferably, the co-catalyst is an alkyl metal compound, further preferably, the alkyl metal compound is selected from at least one of methylaluminoxane, ethylaluminoxane, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diisopropylaluminum hydride, trimethylzinc and triethylzinc, and further preferably, the co-catalyst is methylaluminoxane.

[0027] As a specific embodiment of the present invention, preferably, the terminator is selected from at least one of acidified ethanol, methanol and water; and / or the detergent is an alcohol solvent, more preferably ethanol.

[0028] As a specific embodiment of the present invention, preferably, in step S1, the molar ratio of the NNP-tridentate metal complex and the co-catalyst is 1-200:50-10000; and / or the pressure of the ethylene is 0.1 MPa-10 MPa; and / or the temperature of the ethylene polymerization is 0-120°C.

[0029] As a specific embodiment of the present invention, preferably, in step S1, the molar ratio of the NNP-tridentate metal complex to the co-catalyst is 1:50 to 2000, more preferably 1:50 to 200; and / or the temperature of the ethylene polymerization is 20 to 80°C, more preferably 25 to 50°C.

[0030] As a specific embodiment of the present invention, preferably, the method for ethylene polymerization of the present invention specifically comprises the following steps:

[0031] Under nitrogen protection, add anhydrous metal compounds to the reactor, and then add an appropriate amount of reaction solvent; after dissolving NNP-tridentate organic ligand in the same solvent, add equimolar amounts of NaH in batches, stir and react for 5 minutes, then drop into the above reactor and stir for 10 minutes; connect the high-pressure pipeline to the reactor, pass ethylene gas, add co-catalyst, maintain the corresponding ethylene pressure, react for a corresponding time, remove the high-pressure pipeline, and inject acidified ethanol. Pour the solution into a large amount of ethanol, then filter and collect the polymer, wash with ethanol and vacuum dry overnight.

[0032] The beneficial effects of the present invention are as follows:

[0033] (1) The NNP-tridentate metal complex catalyst provided by the present invention can promote ethylene polymerization to obtain polyethylene. In particular, by adjusting the ratio of the co-catalyst to the NNP-tridentate metal complex, the weight average molecular weight of the polyethylene can be well regulated, thereby preparing low molecular weight polyethylene wax and high molecular weight polyethylene engineering plastics.

[0034] (2) The preparation method of the NNP-tridentate metal complex catalyst provided by the present invention adopts a one-pot preparation method, which is simple to operate, easy to prepare, has reasonable cost, and is suitable for industrial production. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0036] Example 1

[0037] At room temperature (25°C) and under nitrogen protection, anhydrous CrCl3 (5umol) was added to the reactor, and then 5mL of toluene was added; NNP-tridentate organic ligand (ligand of formula II, R = methyl) (5umol) was dissolved in 5mL of toluene, and NaH (5umol) was added. After stirring for 5 minutes, it was added dropwise to the above reactor and stirred for 10 minutes to obtain the corresponding NNP-tridentate metal complex (complex of formula I, R = methyl).

[0038] The high-pressure pipeline was connected to the reactor. After ethylene gas was introduced, methylaluminoxane MAO (250 umol) was added. The ethylene pressure was maintained at 1 atmosphere (101.325 kPa). After reacting for 2 hours, the high-pressure pipeline was removed and 200 mL of acidified ethanol was injected. The resulting solution was poured into a large amount of ethanol, and then the polymer was filtered and collected. After washing with ethanol, it was vacuum dried overnight to obtain 135 mg of polyethylene. The catalyst activity act. = 1.35×10 4 g(PE)·mol -1 (Cr)·h -1 , weight average molecular weight Mw = 1000 g / mol, molecular weight distribution PDI = 1.16, melting point Tm = 118°C.

[0039] Example 2

[0040] The difference from Example 1 is that: CrCl3=5umol, MAO / Cr=2000, ethylene pressure is 10MPa, polyethylene 5890mg is obtained, and catalyst activity act.=5.89×10 5 g(PE)·mol -1 (Cr)·h -1, weight average molecular weight Mw = 1600000 g / mol, molecular weight distribution PDI = 12.05, melting point Tm = 131°C.

[0041] Example 3

[0042] The difference from Example 1 is that: MAO / Cr=1000, toluene is 30 mL, ethylene pressure is 5 MPa, ethylene polymerization temperature is 50° C., and ethylene polymerization reaction time is 1 hour. The results are shown in Table 1.

[0043] Example 4

[0044] The difference from Example 3 is that the solvent is dichloromethane. The results are shown in Table 1.

[0045] Example 5

[0046] The difference from Example 3 is that cyclohexane is used as the solvent. The results are shown in Table 1.

[0047] Table 1

[0048] Example Solvents Yield (mg) <![CDATA[Reactivity (×10 4 g(PE)·mol -1 (Cr)·h -1 )]]> 3 Toluene 462 9.24 4 Dichloromethane 120 2.4 5 Cyclohexane 300 6.0

[0049] As shown in Table 1, in the ethylene polymerization reaction, when the solvent is toluene, the yield is the best, which is 462 mg; while in dichloromethane, the yield is the worst, which is 120 mg.

[0050] Example 6

[0051] The difference from Example 3 is that the co-catalyst is Al( i Bu)3. The results are shown in Table 2.

[0052] Comparative Example 1

[0053] The difference from Example 3 is that the co-catalyst is AlMe3. The results are shown in Table 2.

[0054] Comparative Example 2

[0055] The difference from Example 3 is that the co-catalyst is AlEt2Cl. The results are shown in Table 2.

[0056] Table 2

[0057] Catalyst Yield (mg) <![CDATA[Reactivity (×10 4 g(PE)·mol -1 (Cr)·h -1 )]]> Example 6 <![CDATA[Al( i This)3]]> 390 7.8 Comparative Example 1 <![CDATA[AlMe3]]> Small amount - Comparative Example 2 <![CDATA[AlEt2Cl]]> 0 0

[0058] It can be seen from Table 1 and Table 2 that in the polymerization reaction, when the co-catalyst is MAO, the yield is the best, which is 462 mg; when the co-catalyst is triisobutylaluminum, the yield is second, which is 390 mg; when trimethylaluminum and diethylaluminum chloride are used, almost no polyethylene is obtained.

[0059] The NNP-tridentate metal complex catalyst provided by the present invention can promote ethylene polymerization to obtain polyethylene. In particular, the weight average molecular weight of polyethylene can be well regulated by adjusting the ratio of the co-catalyst and the NNP-tridentate metal complex, so as to prepare low molecular weight polyethylene wax and high molecular weight polyethylene engineering plastics. Specifically, referring to Examples 1 and 2, when the NNP-tridentate metal complex catalyst is used to catalyze ethylene polymerization, the weight average molecular weight Mw of polyethylene can be regulated by adjusting the ratio of the co-catalyst and the NNP-tridentate metal complex from 1000 g / mol to 1600000 g / mol.

[0060] From the above examples, it can be seen that the NNP-tridentate metal complex catalyst provided by the present invention is used for ethylene polymerization, and the weight average molecular weight (Mw) of the obtained polyethylene is 1000-1600000 g / mol, the molecular weight distribution (PDI) with a unimodal model is 1.16-12.05, and Tm=118-131°C.

[0061] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A NNP-tridentate metal complex catalyst, characterized in that: The structure of the NNP-tridentate metal complex is shown in Formula I: Wherein, R is selected from one of substituted or unsubstituted chain alkane groups, substituted or unsubstituted cycloalkane groups, substituted or unsubstituted heterocycloalkane groups, substituted or unsubstituted aromatic groups, and substituted or unsubstituted heteroaromatic groups; and M is selected from Cr, Mo and rare earth metals.

2. The catalyst according to claim 1, characterized in that The substituents in the substituted alkane group, the substituted cycloalkane group, the substituted heterocycloalkane group, the substituted aromatic group and the substituted heteroaromatic group are selected from methyl or phenyl, and / or R is selected from one of substituted or unsubstituted C1-20 alkane group, substituted or unsubstituted C3-20 cycloalkane group, substituted or unsubstituted C2-20 heterocycloalkane group, substituted or unsubstituted C6-20 aromatic group and substituted or unsubstituted C5-20 heteroaromatic group, wherein the heteroatom is selected from at least one of N, O and S; preferably, R is selected from one of substituted or unsubstituted C1-10 alkane group, substituted or unsubstituted C3-10 cycloalkane group, substituted or unsubstituted C2-10 heterocycloalkane group, substituted or unsubstituted C6-10 aromatic group and substituted or unsubstituted C5-10 heteroaromatic group; more preferably, R is selected from one of methyl, ethyl, phenyl and tolyl.

3. A method for preparing the NNP-tridentate metal complex catalyst according to claim 1 or 2, characterized in that: The following steps are involved: (1) mixing a metal M compound with an organic solvent to obtain a metal solution; (2) dissolving the NNP-tridentate organic ligand in the organic solvent, and then adding NaH in an amount equimolar to the NNP-tridentate organic ligand to react; (3) adding the reaction mixture obtained in step (2) dropwise into the metal solution to react and obtain a NNP-tridentate metal complex.

4. The method according to claim 3, characterized in that The structure of the NNP-tridentate organic ligand is shown in Formula II: wherein R is selected from a substituted or unsubstituted alkane group, a substituted or unsubstituted cycloalkane group, a substituted or unsubstituted heterocycloalkane group, a substituted or unsubstituted aromatic group, or a substituted or unsubstituted heteroaromatic group; preferably, R is selected from a substituted or unsubstituted C1-20 alkane group, a substituted or unsubstituted C3-20 cycloalkane group, a substituted or unsubstituted C2-20 heterocycloalkane group, a substituted or unsubstituted C6-20 aromatic group, or a substituted or unsubstituted C5-20 heteroaromatic group, wherein the heteroatom is selected from at least one of N, O, and S; more preferably, R is selected from a substituted or unsubstituted C1-10 alkane group, a substituted or unsubstituted C3-10 cycloalkane group, a substituted or unsubstituted C2-10 heterocycloalkane group, a substituted or unsubstituted C6-10 aromatic group, or a substituted or unsubstituted C5-10 heteroaromatic group; more preferably, R is selected from a methyl group, an ethyl group, a phenyl group, or a tolyl group; And / or, the metal M compound is selected from at least one of chromium chloride, molybdenum chloride, scandium chloride, yttrium chloride, lanthanum chloride and cerium chloride; And / or, the organic solvent is selected from at least one of dioxane, chloroform, n-hexane, n-heptane, benzene, toluene, cyclohexane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, trichlorobenzene and tetrahydrofuran, preferably toluene.

5. Use of the NNP-tridentate metal complex catalyst according to claim 1 or 2 or the NNP-tridentate metal complex catalyst obtained by the method according to claim 3 or 4 in ethylene polymerization, preferably, the ethylene polymerization is ethylene homopolymerization.

6. A method for ethylene polymerization, characterized in that: The following steps are involved: S1, adding the NNP-tridentate metal complex according to claim 1 or 2 or the method according to claim 3 or 4 to obtain the NNP-tridentate metal complex in a reaction vessel, then introducing ethylene gas, and then adding a co-catalyst to polymerize ethylene; S2, stop feeding ethylene, and add a terminator to the reaction mixture obtained in step S1; S3. Pour the reaction mixture obtained in step S2 into a detergent, and then filter, wash and dry to obtain polyethylene.

7. The method according to claim 6, characterized in that The co-catalyst is an alkyl metal compound. Preferably, the alkyl metal compound is selected from at least one of methylaluminoxane, ethylaluminoxane, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diisopropylaluminum hydride, trimethylzinc and triethylzinc. More preferably, the co-catalyst is methylaluminoxane.

8. The method according to claim 6 or 7, characterized in that: The terminator is selected from at least one of acidified ethanol, methanol and water; and / or the detergent is an alcohol solvent, preferably ethanol.

9. The method according to claim 6 or 7, characterized in that: In step S1, the molar ratio of the NNP-tridentate metal complex to the co-catalyst is 1-200:50-10000; and / or the pressure of the ethylene is 0.1 MPa-10 MPa; and / or the temperature of the ethylene polymerization is 0-120°C.

10. The method according to claim 9, characterized in that In step S1, the molar ratio of the NNP-tridentate metal complex to the co-catalyst is 1:50 to 2000, preferably 1:50 to 200; and / or the temperature of the ethylene polymerization is 20 to 80°C, preferably 25 to 50°C.

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