High-selectivity catalyst, preparation method and application in ethylene oligomerization reaction

Abstract

The invention discloses a high-selectivity catalyst. The catalyst is prepared from the following raw materials: a phosphine-containing ligand, a transition metal compound and an organic solvent, the structural formula of the phosphine-containing ligand is shown in the following formula: # imgabs0 #, wherein n is an integer in the range of 2-10; r1, R2 and R3 are the same or different, and R1, R2 and R3 are selected from one or a combination of more of C2-C9 alkyl, aryl, substituted alkyl and substituted aryl. The chromium catalyst containing the phosphorus ligand and the organic aluminum compound are adopted as a double-catalysis system for ethylene polymerization, ethylene oligomerization can be achieved, high selectivity to 1-hexene and 1-octene is achieved, and the catalytic activity is high. A double-center catalytic system is adopted, on the basis of ensuring catalytic activity, generation of solid polymers is reduced, scaling of equipment and pipelines in the production process is avoided, and long-term continuous production is achieved.

Description

Technical Field

[0001] The invention relates to a high-selectivity catalyst, a preparation method and application in ethylene oligomerization reaction, and relates to B01J, in particular to the field of complexes. Background Art

[0002] Linear α-olefins are important polyolefin comonomers. With the in-depth study, it is found that 1-hexene and 1-octene can significantly improve the mechanical properties and service life of polyethylene when used as comonomers. 10 Linear α-olefins are the main raw materials for the production of plasticizer intermediates and are widely used in actual production. Traditional 1-hexene and 1-octene have low selectivity, high reaction energy consumption, and difficult product separation. In order to achieve higher selectivity and improve catalytic activity, a variety of catalysts have been developed. In the ethylene polymerization reaction, iron-based, titanium-based, tantalum-based, chromium-based and zirconium-based catalysts have shown good catalytic performance, but the excessive amount of polymers generated during the reaction will cause blockage of the reactor and pipeline, affecting the long-term operation of the experimental device.

[0003] Chinese invention patent CN202210467716.7 discloses a modified PNP catalyst ligand, its preparation method and an ethylene selective polymerization catalyst. The generated ligand has multiple active centers after complexing with chromium. The generated oligoolefins can be separated from the catalyst, and the polymer grows in the styrene pores, which can reduce solid wall hanging and metal catalyst loss. The catalytic reaction activity is about 600, which is relatively low. Patent US 20100137669 discloses a PCCP-type symmetrical skeleton catalyst. Under the same reaction conditions, the polymerization activity of PCCP is higher than that of PNP ligand, but more polymers will be generated, resulting in scaling of reactors and pipelines, affecting the long-term continuous operation of the production unit. Summary of the invention

[0004] In order to improve the selectivity of 1-hexene and 1-octene in the ethylene polymerization reaction, the first aspect of the present invention provides a highly selective catalyst, the catalyst preparation raw materials include phosphine-containing ligands, transition metal compounds, organic solvents; the structural formula of the phosphine-containing ligand is shown in the following formula: Wherein n is an integer in the range of 2-10; R1, R2, and R3 are independently selected from one or a combination of C2-C9 alkyl, aryl, substituted alkyl, and substituted aryl.

[0005] As a preferred embodiment, R1, R2, and R3 are each independently selected from phenyl, benzyl, biphenyl, naphthyl, anthracenyl, nitro, nitroso, chloro, amino, vinyl, propenyl, isopropyl, tert-butyl, cyclohexyl, 4-methylcyclohexyl, 4-ethylcyclohexyl, 4-isopropylcyclohexyl, 2-methylphenyl, 4-methylphenyl, 2,4-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, 4-ethylphenyl, 2,4-diethylphenyl, 2,6-diethylphenyl, 2-isopropylphenyl, 4-isopropylphenyl, 2,4-diisopropylphenyl, 2,6-diisopropylphenyl, 2- One of butylphenyl, 4-butylphenyl, 2,4-dibutylphenyl, 2,6-dibutylphenyl, 4-methoxyphenyl, o-methoxyphenyl, 4-ethoxyphenyl, o-ethoxyphenyl, 2-(trimethylsilyl)phenyl, 3-(trimethylsilyl)phenyl, 4-(trimethylsilyl)phenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2-(trifluoromethyl)phenyl, 3-(trifluoromethyl)phenyl, 4-(trifluoromethyl)phenyl, 3,5-bis(trifluoromethyl)phenyl, 2-(tri-n-butylsilyl)phenyl, 3-(tri-n-butylsilyl)phenyl and 4-(tri-n-butylsilyl)phenyl.

[0006] As a preferred embodiment, the phosphine-containing ligand is prepared through an acetylene intermediate, and the raw materials for preparing the acetylene intermediate include triethylamine, chlorine-containing phosphide I, and acetylene amine; the raw materials for preparing the phosphine-containing ligand include acetylene intermediate, solvent A, alkyl lithium reagent, chlorine-containing phosphide II, copper catalyst, inorganic base, substituted phosphine, and solvent B.

[0007] As a preferred embodiment, the method for preparing the phosphine-containing ligand comprises the following steps:

[0008] S1: dissolve triethylamine in dichloromethane, add chlorine-containing phosphide I dropwise, stir in an ice-water bath after the addition is complete, add alkynylamine dropwise for 20-30 min, stir in an ice-water bath for 0.5-1 h after the addition is complete, react at room temperature for 10-20 h, and purify the reaction solution to obtain diphosphine;

[0009] S2: Dissolve the diphosphine in solvent A, add an alkyl lithium reagent dropwise under stirring in an ice-water bath for 1-2 hours, react at -75 to -80°C for 1-5 hours, slowly add chlorine-containing phosphide II, react for 1-10 hours, purify and obtain the product; dissolve the product, copper catalyst, inorganic base and substituted phosphine in solvent B, react for 1-10 hours, purify the reaction solution to obtain the phosphine-containing ligand.

[0010] As a preferred embodiment, the structural formula of the chlorine-containing phosphide is PR1 R2Cl, and the structural formula of the substituted phosphine is P(R3)2H; R1, R2, and R3 are each independently selected from one or a combination of C2-C9 alkyl, aryl, substituted alkyl, and substituted aryl.

[0011] As a preferred embodiment, the molar ratio of the alkynamine to the chlorine-containing phosphide I is 1:(1-1.5); the molar ratio of the triethylamine to the chlorine-containing phosphide I is 1:(3-10).

[0012] As a preferred embodiment, the alkynamine is selected from one or a combination of acetyleneamine, propynylamine, butynylamine, pentynylamine, hexynylamine, heptynylamine, octynylamine, nonynylamine and decynylamine.

[0013] As a preferred embodiment, the solvent A is selected from one or a combination of tetrahydrofuran, dioxane, diethyl ether, and 2-methyltetrahydrofuran; the solvent B is selected from one or a combination of N,N-dimethylformamide and N,N-dimethylacetamide.

[0014] As a preferred embodiment, the alkyne intermediate is bisphosphine alkyne; the molar ratio of the alkyl lithium reagent to the bisphosphine alkyne is 1:(1-1.5); the molar ratio of the bisphosphine alkyne to the chlorine-containing phosphide II is 1:(0.9-1.1).

[0015] As a preferred embodiment, the molar ratio of the copper catalyst, the inorganic base, and the substituted phosphine is (0.1-0.2): (0.1-0.2): (1-1.2).

[0016] As a preferred embodiment, the molar ratio of the product, the copper catalyst, the inorganic base, and the substituted phosphine is 1:(0.1-0.2):(0.1-0.2):(1-1.2).

[0017] As a preferred embodiment, the copper catalyst is selected from cuprous iodide, cupric chloride, cuprous oxide, or a combination thereof.

[0018] As a preferred embodiment, the inorganic base is selected from one or a combination of cesium carbonate, potassium carbonate and sodium hydroxide.

[0019] As a preferred embodiment, the molar ratio of the phosphine-containing ligand to the transition metal compound is (1-2):1.

[0020] As a preferred embodiment, the metal in the transition metal compound is selected from one or a combination of chromium, molybdenum, cobalt, titanium, vanadium, zirconium, nickel, palladium; preferably, the metal in the transition metal compound is selected from one or a combination of chromium, zirconium, nickel. More preferably, the metal in the transition metal compound is chromium.

[0021] As a preferred embodiment, the transition metal compound is selected from one or a combination of chromium chloride, chromium acetylacetonate, chromium octoate, chromium isooctanoate, diisoprene chromium, diphenyl chromium, tetrahydrofuran chromium dichloride, tetrahydrofuran chromium trichloride, chromium 2-ethylhexanoate, and chromium hexacarbonyl.

[0022] As a preferred embodiment, the organic solvent is toluene that has been dehydrated.

[0023] The second aspect of the present invention provides a method for preparing a highly selective catalyst, comprising the following steps: adding a phosphine-containing ligand, a transition metal compound and an organic solvent into a nitrogen-substituted reaction bottle, and reacting at 80-90° C. for 5-10 hours to obtain a catalyst.

[0024] The third aspect of the present invention provides an application of a highly selective catalyst for use in an ethylene polymerization reaction; the process steps of the ethylene polymerization reaction are as follows:

[0025] H1 heats the reactor to 100-180°C, evacuates for 1-3h, cools to room temperature, and replaces with nitrogen 3-5 times;

[0026] Vacuum with H2, then introduce ethylene, add solvent C and co-catalyst after the temperature is constant, then add solvent C and the prepared catalyst, and react at 20-90°C, 1-6MPa for 10-120min;

[0027] After the H3 reaction, cool down in an ice water bath, reduce the pressure, quench the reaction, filter the solid product, and dry it.

[0028] As a preferred embodiment, the solvent C is selected from one or a combination of n-butane, isobutane, n-pentane, cyclopentane, methylcyclopentane, methylenecyclopentane, n-hexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, n-nonane, benzene, toluene, xylene, o-xylene, and ethylbenzene.

[0029] As a preferred embodiment, the co-catalyst is an alkyl aluminum or aluminoxane, and the co-catalyst is selected from one or a combination of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trioctylaluminum, diethyl aluminum monochloride, ethyl aluminum dichloride, methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, propylaluminoxane, butylaluminoxane, isopropylaluminoxane, and tert-butylaluminoxane.

[0030] More preferably, the co-catalyst is methylaluminoxane and / or modified methylaluminoxane.

[0031] As a preferred embodiment, the amount of ethylene added is 0.2-0.8 MPa.

[0032] As a preferred embodiment, the prepared catalyst is a main catalyst, and the molar ratio of the main catalyst to the co-catalyst is 1:(50-2000); further preferably, the molar ratio of the main catalyst to the co-catalyst is 1:(100-1500); preferably, the molar ratio of the main catalyst to the co-catalyst is 1:800.

[0033] As a preferred embodiment, the total selectivity of 1-hexene and 1-octene in the oligomerization reaction is

[0034] ≥50%, and more preferably, the total selectivity of 1-hexene and 1-octene in the oligomerization reaction is ≥70%.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The highly selective catalyst of the present invention uses a chromium catalyst containing a phosphorus ligand and an organic aluminum compound as a dual catalytic system for ethylene polymerization, which can achieve ethylene polymerization, achieve high selectivity for 1-hexene and 1-octene, and have high catalytic activity.

[0037] (2) The highly selective catalyst of the present invention uses a phosphorus-containing ligand and tetrahydrofuran chromium trichloride to synthesize the catalyst, has high catalytic activity, and has high selectivity for 1-hexene and 1-octene.

[0038] (3) The highly selective catalyst of the present invention is applied to ethylene polymerization reaction, and adopts a dual-center catalytic system. On the basis of ensuring the catalytic activity, it also reduces the generation of solid polymers, avoids scaling of equipment and pipelines in the production process, and realizes long-term continuous production.

[0039] (4) The highly selective catalyst of the present invention is applied to ethylene polymerization reaction. By adjusting the carbon chain length of the substituent on N and the steric hindrance of the substituent on P, the ratio of 1-hexene to 1-octene in the polymerization product can be controlled.

[0040] (5) The highly selective catalyst of the present invention is applied to ethylene polymerization reaction, and has high selectivity for 1-hexene and 1-octene, low production energy consumption, and easy separation of products. DETAILED DESCRIPTION

[0041] Example 1

[0042] A highly selective catalyst, wherein the raw materials for preparing the catalyst include a phosphine-containing ligand, a transition metal compound, and an organic solvent; the structural formula of the phosphine-containing ligand is as follows:

[0043] The phosphine-containing ligand is prepared through an acetylene intermediate, and the raw materials for preparing the acetylene intermediate include triethylamine, chlorine-containing phosphide I, and acetylene amine; the raw materials for preparing the phosphine-containing ligand include acetylene intermediate, solvent A, alkyl lithium reagent, chlorine-containing phosphide II, copper catalyst, inorganic base, substituted phosphine, and solvent B.

[0044] The preparation method of the phosphine-containing ligand comprises the following steps:

[0045] S1: Dissolve triethylamine in dichloromethane, add chlorine-containing phosphide I dropwise, stir in an ice-water bath after the addition is complete, add alkynylamine dropwise for 20 min, stir in an ice-water bath for 0.5 h after the addition is complete, react at room temperature for 15 h, and purify the reaction solution to obtain bisphosphine;

[0046] S2: Dissolve the diphosphine in solvent A, add alkyl lithium reagent dropwise under stirring in an ice-water bath for 1 hour, react at -78°C for 3 hours, slowly add chlorine-containing phosphide II, react for 5 hours, purify and obtain the product; dissolve the product, copper catalyst, inorganic base and substituted phosphine in solvent B, react for 5 hours, purify the reaction solution to obtain the phosphine-containing ligand.

[0047] The structural formulas of the chlorine-containing phosphides I and II are both P(Ph)2Cl, and the structural formula of the substituted phosphine is P(Ph)2H.

[0048] The molar ratio of the alkynamine to the chlorine-containing phosphide I is 1:1; the molar ratio of the triethylamine to the chlorine-containing phosphide I is 1:6.5.

[0049] The alkynamine is butynamine.

[0050] The solvent A is tetrahydrofuran; the solvent B is N,N-dimethylformamide.

[0051] The molar ratio of the alkyl lithium reagent to the diphosphine is 1:1; the molar ratio of the diphosphine to the chlorine-containing phosphide II is 1:1.

[0052] The alkyl lithium reagent is a hexane solution containing 1.6 M n-butyl lithium.

[0053] The molar ratio of the product, the copper catalyst, the inorganic base and the substituted phosphine is 1:0.15:0.15:1.1.

[0054] The copper catalyst is copper chloride, and the inorganic base is cesium carbonate.

[0055] The transition metal compound is tetrahydrofuran chromium trichloride.

[0056] The organic solvent is redistilled toluene.

[0057] A method for preparing a highly selective catalyst comprises the following steps: adding 10 mL of redistilled toluene, a phosphine-containing ligand (0.33 g, 0.41 mmol) and CrCl3(THF)3 (0.15 g, 0.40 mmol) into a reaction bottle replaced with nitrogen, and reacting at 80°C for 8 hours to obtain a catalyst.

[0058] The highly selective catalyst is applied to ethylene polymerization reaction, and the process steps are as follows:

[0059] H1 heated the reactor to 120°C, evacuated and maintained for 1 h, cooled to 25°C, and replaced with nitrogen three times;

[0060] Vacuum with H2, then introduce 0.3MPa ethylene twice, add 30mL solvent C and co-catalyst after the temperature is constant, then add 20mL solvent C and main catalyst, add ethylene at 45°C until the reaction pressure reaches 4MPa and react for 30min;

[0061] After the H3 reaction, the temperature was cooled in an ice-water bath, the pressure was lowered, the reaction was quenched, the solid product was filtered, and vacuum dried at 60°C for 8 h.

[0062] The solvent C is toluene, and the co-catalyst is methylaluminoxane.

[0063] The main catalyst is a prepared catalyst, and the molar ratio of the main catalyst to the co-catalyst is 1:800.

[0064] Example 2

[0065] A highly selective catalyst, a preparation method and an application in ethylene polymerization reaction. The specific implementation method is the same as that of Example 1, except that the reaction temperature in the ethylene polymerization reaction step H2 is 60°C.

[0066] Example 3

[0067] A highly selective catalyst, a preparation method and an application in ethylene polymerization reaction. The specific implementation method is the same as that of Example 1, except that the reaction pressure in the ethylene polymerization reaction step H2 is 3.0 MPa.

[0068] Example 4

[0069] A highly selective catalyst, a preparation method and an application in ethylene oligomerization reaction, the specific implementation method is the same as that of Example 1, except that the structural formula of the phosphine-containing ligand is as follows:

[0070]

[0071] The alkynylamine is hexynylamine.

[0072] Example 5

[0073] A highly selective catalyst, a preparation method and an application in ethylene polymerization reaction. The specific implementation method is the same as that of Example 4, except that the reaction temperature in the ethylene polymerization reaction step H2 is 60°C.

[0074] Example 6

[0075] A highly selective catalyst, a preparation method and an application in ethylene polymerization reaction. The specific implementation method is the same as that of Example 4, except that the reaction pressure in the ethylene polymerization reaction step H2 is 3.0 MPa.

[0076] Example 7

[0077] A highly selective catalyst, a preparation method and an application in ethylene oligomerization reaction, the specific implementation method is the same as that of Example 1, except that the structural formula of the phosphine-containing ligand is as follows:

[0078]

[0079] The structural formulas of the chlorine-containing phosphides I and II are both P(o-OMePh)2Cl, and the structural formula of the substituted phosphine is P(Ph)2H.

[0080] Performance Testing

[0081] The distribution of the oligomerization products was determined by gas chromatography and mass spectrometry. The obtained products are given in Table 1.

[0082] Composition of the substance:

[0083] Table 1

[0084]

[0085] It can be seen from Table 1 that the catalyst provided by the present invention has high catalytic activity and high selectivity for 1-hexene and 1-octene, and the ratio of 1-hexene and 1-octene in the oligomerization product can be regulated by adjusting the carbon chain length of the substituent on N and the steric hindrance of the substituent on P.

Claims

1. A highly selective catalyst, characterized in that: The catalyst preparation raw materials include phosphine-containing ligands, transition metal compounds, and organic solvents; the structural formula of the phosphine-containing ligands is shown below: Wherein n is an integer in the range of 2-10; R1, R2, and R3 are independently selected from one or a combination of C2-C9 alkyl, aryl, substituted alkyl, and substituted aryl.

2. The highly selective catalyst according to claim 1, characterized in that The phosphine-containing ligand is prepared through an acetylene intermediate, and the raw materials for preparing the acetylene intermediate include triethylamine, chlorine-containing phosphide I, and acetylene amine; the raw materials for preparing the phosphine-containing ligand include acetylene intermediate, solvent A, alkyl lithium reagent, chlorine-containing phosphide II, copper catalyst, inorganic base, substituted phosphine, and solvent B.

3. The highly selective catalyst according to claim 2, characterized in that: The structural formulas of the chlorine-containing phosphides I and II are both PR1 R2Cl, and the structural formula of the substituted phosphine is P(R3)2H; R1, R2, and R3 are independently selected from one or a combination of C2-C9 alkyl, aryl, substituted alkyl, and substituted aryl.

4. The highly selective catalyst according to claim 2, characterized in that: The molar ratio of the alkynamine to the chlorine-containing phosphide I is 1:(1-1.5); the molar ratio of the triethylamine to the chlorine-containing phosphide I is 1:(3-10).

5. The highly selective catalyst according to claim 2, characterized in that: The solvent A is selected from one or a combination of tetrahydrofuran, dioxane, ether, and 2-methyltetrahydrofuran; and the solvent B is selected from one or a combination of N,N-dimethylformamide and N,N-dimethylacetamide.

6. The highly selective catalyst according to claim 2, characterized in that: The alkyne intermediate is diphosphine alkyne; the molar ratio of the alkyl lithium reagent to the diphosphine alkyne is 1:(1-1.5); the molar ratio of the diphosphine alkyne to the chlorine-containing phosphide II is 1:(0.9-1.1).

7. The highly selective catalyst according to claim 2, characterized in that: The molar ratio of the copper catalyst, the inorganic base and the substituted phosphine is (0.1-0.2): (0.1-0.2): (1-1.2).

8. The highly selective catalyst according to claim 1, characterized in that The molar ratio of the phosphine-containing ligand to the transition metal compound is (1-2):

1.

9. A method for preparing a highly selective catalyst according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: adding a phosphine-containing ligand, a transition metal compound and an organic solvent into a reaction bottle replaced with nitrogen, and reacting at 80-90° C. for 5-10 hours to obtain a catalyst.

10. Use of a highly selective catalyst according to any one of claims 1 to 8, characterized in that: Applied to ethylene polymerization reaction; the process steps of the ethylene polymerization reaction are as follows: H1 heats the reactor to 100-180°C, evacuates for 1-3h, cools to room temperature, and replaces with nitrogen 3-5 times; Vacuum with H2, then introduce ethylene, add solvent C and co-catalyst after the temperature is constant, then add solvent C and the prepared catalyst, and react at 20-90°C, 1-6MPa for 10-120min; After the H3 reaction, cool down in an ice water bath, reduce the pressure, quench the reaction, filter the solid product, and dry it.

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