CN106582851A - Catalyst component for selective oligomerization of ethylene and catalyst thereof - Google Patents

Abstract

The present invention relates to a catalyst component for selective oligomerization of ethylene and its catalyst. The catalyst component is a compound of general formula (I), or contains two or more compounds of general formula (I). The compound that structural unit connects to form by group or chemical bond; The structure of general formula (I) is as follows: Among them, n is an integer, 0≤n≤4; Ph ₁ , Ph ₂ , Ph ₃ , Ph ₄ are selected from phenyl, substituted phenyl and their derivatives; R ₁ , R ₂ , R ₃ are selected from phenyl, chain Like alkyl, cyclic alkyl and their derivatives. The catalyst of the invention has high activity, high selectivity of target products 1-hexene+1-octene, and less 1-butene and 1-C10 ⁺ . The catalytic agent has the characteristics of simple synthesis, low cost, and long catalyst life. The mass percentage of C ₆ -C ₈ linear α-olefins in the product is >90%, and the mass percentage of C ₈ linear α-olefins is >60%.

Description

Catalyst components and catalysts for selective oligomerization of ethylene

technical field

The invention belongs to the field of olefin oligomerization catalysis, and relates to a catalyst for olefin selective oligomerization, which is a catalyst component and catalyst for olefin selective oligomerization, especially related to olefin selective trimerization and tetramerization, Preparation method, application.

technical background

Linear α-olefins are an important class of organic chemical raw materials, which are widely used in the production of polyethylene, surfactants, lubricating oils and oil additives. The light components (C ₄ -C ₈ olefins) can be used as comonomers to copolymerize with ethylene to produce high-performance linear low-density polyethylene. In particular, high-purity 1-hexene and 1-octene can significantly improve the abrasion resistance and other chemical and mechanical properties of linear low-density polyethylene. With the continuous development of the global economy, the demand for high-performance polyethylene continues to grow, and the demand for 1-hexene and 1-octene continues to grow at an average annual rate of more than 5%. The industrial production methods of 1-hexene and 1-octene mainly include paraffin cracking, ethylene oligomerization and extraction separation, among which ethylene oligomerization is the main method for producing 1-hexene and 1-octene. For example, US6184428 discloses a nickel catalyst using a boron compound as a cocatalyst, which can catalyze the oligomerization of ethylene to obtain a mixture of linear α-olefins, wherein the content of 1-hexene accounts for 22%, and the content of 1-octene accounts for 19%. The SHOP process (US3676523, US3635937) uses a similar catalytic system, and the content of 1-hexene in the oligomerization product accounts for 21%, and the content of 1-octene accounts for 11%. In other typical ethylene oligomerization processes, such as the Chevron process (DE1443927) of Gulf Oil Company and the ethylene oligomerization process of Ethyl Corporation (BP/Amoco, US3906053), the content of 1-hexene and 1-octene is generally 13 ~25%. Iron-based catalysts reported by Brookhart et al. (J.Am.Chem.Soc., 1998,120:7143; Chem.Commun.1998,849; WO 99/02472) are used for ethylene oligomerization, and its 1-hexene, 1- The content of octene is also low (<20%). The carbon numbers of linear α-olefins in these production processes conform to the Schulz-Flory distribution, which makes it impossible for the content of 1-hexene and 1-octene in the oligomerization products to be too high. To obtain high-purity 1-hexene and 1-octene needs to be separated by multi-column rectification, the process route is complicated and the investment in equipment is huge. Therefore, it is very important to find a production process for the preparation of 1-hexene and 1-octene with high selectivity. Catalytic ethylene high-selectivity oligomerization is the main method for producing 1-hexene and 1-octene, and the catalyst is the key Technology, the development of new catalytic systems and the study of their catalytic mechanism have always been hot and difficult issues in this field. In recent years, scientific researchers have carried out a lot of research on ethylene selective oligomerization technology, and also obtained many important research results. Such as: chromium-based catalyst system is used for ethylene trimerization to prepare 1-hexene, and industrialized production has also been realized (US5550305, US5198563), but the content of its main product 1-hexene is generally all greater than 90%, and the content of 1-octene Rarely (<3%). The recently reported ethylene tetramerization three-way catalyst system can synthesize 1-octene with high selectivity (WO2004/056478A1, US2006/0229480 and US 2006/0173226), and the content of 1-octene in the target product reaches 60%. In recent years, with the deepening of research on ethylene highly selective trimerization and tetramerization, the development of catalysts for highly selective ethylene oligomerization, especially chromium-based catalysts for tetramerization and pentamerization of ethylene, has become a research hotspot. At present, the central metals of ethylene selective trimerization catalysts are mainly chromium and titanium, and the central metals of ethylene tetramerization catalysts are mainly chromium. Ligands play an important role in the ethylene selective oligomerization catalytic system, and the structure of the ligand directly affects the product selectivity of the ethylene selective oligomerization catalytic system. Therefore, it is very important to design and synthesize ligands with new structures. research hotspots in this field.

Contents of the invention

The purpose of the present invention is to provide a catalyst system for highly selective trimerization and tetramerization of ethylene and a method for catalyzing trimerization and tetramerization of ethylene. Compared with the prior art, the catalyst system can maintain higher catalytic activity. , improve the co-selectivity of 1-hexene and 1-octene, and reduce the selectivity of the by-product low molecular weight polyethylene.

The catalyst of the present invention is a three-component catalyst composed of a heteroatom ligand (a), a transition metal compound (b) and an organometallic compound activator (c). The catalyst is used for the selective oligomerization of olefins, especially for the highly selective preparation of 1-hexene and 1-octene. The heteroatom-containing ligand (a) is a compound shown in the following general formula (I):

Among them, n is an integer, 0≤n≤4; Ph ₁ , Ph ₂ , Ph ₃ , Ph ₄ are selected from phenyl, substituted phenyl and their derivatives; R ₁ , R ₂ , R ₃ are selected from phenyl, chain Like alkyl, cyclic alkyl and their derivatives. The heteroatom-containing ligand (a) can also be a new compound that contains two or more structural units that meet the general formula (I) and are connected by groups or chemical bonds; the transition metal compound (b) is a compound of chromium, molybdenum, tungsten, titanium, tantalum, vanadium, zirconium, iron, nickel, palladium; said organometallic compound activator (c) is an alkyl aluminum compound, aluminoxane compound, organic boron Compound, organic salt, inorganic acid and inorganic salt, also can be the mixture of one or more in them; In described catalyzer, the molar ratio of the component (a), (b) and (c) that comprises is (a):(b):(c)=1:0.5～100:0.1～5000; the three components (a), (b) and (c) are pre-mixed; or can be directly added to the reaction In-situ synthesis in the system; the catalyst component is used for selective oligomerization of ethylene, and the reaction is carried out in an inert solvent, which can be selected from alkanes, cycloalkanes, aromatics, olefins, and ionic liquids; the reaction temperature is 0°C~ At 200°C, the reaction pressure is 0.1MPa-50MPa to produce ethylene oligomerization products.

Specify the reaction product of the catalytic system containing the following components:

(1) at least one heteroatom-containing ligand (a) selected from general formula (I)

In the formula, n is an integer, 0≤n≤4; Ph ₁ , Ph ₂ , Ph ₃ , Ph ₄ can be benzyl, phenyl, tolyl, xylyl, 2,4,6-trimethylphenyl, 3,5-xylyl, methoxyphenyl, ethylphenyl, thiophenyl, bisphenyl, naphthyl, anthracenyl, etc. Preferred Ph ₁ , Ph ₂ , Ph ₃ , Ph ₄ are phenyl, substituted phenyl, xylyl, biphenyl, naphthyl and thiophenyl; R ₁ , R ₂ , R ₃ are selected from phenyl, chain Like alkyl, cyclic alkyl and their derivatives.

(2) A transition metal compound (b)

Alternative transition metal compounds are compounds of chromium, molybdenum, tungsten, titanium, tantalum, vanadium, zirconium, iron, nickel, palladium. Preferred are chromium, zirconium, titanium compounds, most preferably chromium compounds. Optional chromium compounds include those compounds represented by the general formula CrR ⁿ _m , where R ⁿ is an organic negative ion or a neutral molecule, usually contains 1 to 10 carbon atoms in R ⁿ , and n is an integer of 0 to 6, The valence state of chromium is 0-6. The specific R ⁿ group is, for example, an organic compound containing a carboxyl group, a β-diketone group and a hydrocarbon group or a group thereof. From the viewpoint of ease of dissolution and handling, more suitable chromium compounds include chromium acetate, chromium isooctanoate, chromium n-octanoate, chromium acetylacetonate, diisoprene chromium, diphenyl chromium, CrCl ₃ (THF) ₃ , CrCl ₂ (THF) ₂ , (phenyl) chromium tricarbonyl, chromium hexacarbonyl and a mixture of more than one. The most preferred chromium compounds are CrCl ₃ (THF) ₃ , chromium isooctanoate, chromium acetylacetonate.

(3) A kind of organometallic compound active agent (c)

Alternative organometallic compounds include alkylaluminum compounds, aluminoxane compounds, organoboron compounds, organic salts, inorganic acids and inorganic salts. Specifically selected from various trialkylaluminum and aluminoxane compounds, such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, methylaluminum Oxane, ethylalumoxane, isobutylalumoxane and modified alumoxane, etc. Alkyl aluminum halides, alkyl aluminum hydrides or alkyl aluminum sesquichlorides, such as AlEt ₂ Cl and Al ₂ Et ₃ Cl ₃ , can also be used with one or more of the above-mentioned alkyl Mixtures of aluminum or aluminoxanes. Organic salt activators such as methyl lithium, methyl magnesium bromide, etc.; inorganic acids and inorganic salt activators such as tetrafluoroborate etherate, tetrafluoroborate, hexafluoroantimonate, etc. Organoboron compounds include boroxine, sodium borohydride, triethylborane, tris(pentafluorophenyl)boron, tributylborate, and the like.

The synthesis of the heteroatom-containing ligand (a) can be carried out by the following methods: ① Preparation of diphenylphosphinolithium or diphenylphosphinopotassium. First disperse a certain amount of diphenylphosphine in an appropriate amount of n-hexane, then add n-butyllithium or potassium hydride dropwise at a certain temperature to prepare diphenylphosphinolithium or diphenylphosphinopotassium; Chlorosilanes. Dissolve a certain amount of dihydrocarbyl substituted dichlorosilane in an appropriate amount of n-hexane, cool down to a certain temperature, and then add diphenylphosphinolithium or diphenylphosphinopotassium solids to the above solution several times in small amounts, naturally Raise to room temperature, stir overnight, and vacuum remove the volatile components in the filtrate after filtration to obtain a yellow oily crude product, which is separated by distillation to obtain a colorless or light yellow oily product; ③ preparation of a monophosphine amine intermediate. Dissolve a certain amount of primary amine compound in n-hexane, cool to a certain temperature, slowly add a certain amount of n-butyllithium n-hexane solution to the above solution dropwise, naturally rise to room temperature, stir overnight, filter and wash with an appropriate amount of n-hexane Finally, the filter cake is drained to obtain the lithium salt of the primary amine compound. Disperse the lithium salt of the primary amine compound in an appropriate amount of n-hexane, cool to a certain temperature, slowly add a certain amount of the n-hexane solution of the dihydrocarbyl substituted phosphorus chloride compound into the above lithium salt dropwise, naturally rise to room temperature, and stir overnight, After removing the volatile components in a vacuum, extract the residue with an appropriate amount of toluene, filter and remove the volatile components in a vacuum to obtain a yellow crude product, and then wash with an appropriate amount of n-hexane to obtain a white or light yellow product. ④ Preparation of ligand: Dissolve a certain amount of monophosphine amine intermediate in dehydrated n-hexane, cool to a certain temperature, slowly add a certain amount of n-butyllithium n-hexane solution into the above solution, and dropwise Then naturally rise to room temperature, continue to stir overnight, wash the filter cake with a certain amount of n-hexane after filtration, and obtain monophosphine amine lithium salt after drying, then disperse the modified lithium salt in n-hexane, and at a certain temperature, a certain amount of The phosphinochlorosilane was slowly added dropwise to the above solution, naturally raised to room temperature, stirred overnight, the volatile components were vacuumed off, the residue was extracted with an appropriate amount of toluene, and the volatile components were vacuum pumped after filtration to obtain the ligand product .

The molar ratio of the heteroatom-containing ligand (a) to the transition metal compound (b) in the catalyst is 1:0.5-100.

The molar ratio of the heteroatom-containing ligand (a) in the catalyst to the organometallic compound activator (c) is 1:0.1 to 1:5000, preferably 1:1 to 1:1000, more preferably 1:1 ~1:200.

The heteroatom ligands mentioned in (I) can also be one or more units of the structure of formula (I), which are combined through groups, chemical bonds or intermolecular forces. If bridged, dendritic and star-shaped compounds are obtained, they can also be polymerized polymers formed by combining with polymer chains.

The reaction mode of the ligand of heteroatom described in (I), transition metal compound and organometallic activator, can be by liquid phase reaction, as reacting under the effect of solvent, optional solvent such as toluene, benzene and its Derivatives, etc.; also by solid-state reaction; also by in-situ reaction in the process of oligomerization to generate catalyst. The reaction described here may be a reaction among one, two or three compounds of the above heteroatom ligands, transition metal compounds and organometallic activators. The process of this reaction is also the aging (pre-complexation) process of the catalyst.

The selective oligomerization of ethylene is mainly carried out in an inert solvent. Alternative solvents include alkanes, cycloalkanes, aromatics, halogenated hydrocarbons, alkenes, and the like. Typical solvents include, but are not limited to, benzene, toluene, xylene, cumene, n-heptane, n-hexane, methylcyclohexane, cyclohexane, 1-hexene, 1-octene, ionic liquids, and the like.

The preparation of the catalyst is to pre-mix the heteroatom-containing ligand (a), transition metal compound (b), organometallic compound activator (c); also the heteroatom-containing ligand (a), transition metal compound ( b), the organometallic compound activator (c) is directly added to the reaction system for in-situ synthesis;

The temperature of ethylene selective oligomerization can be carried out within 0°C to 200°C, preferably 50°C to 150°C. The pressure of ethylene tetramerization reaction can be carried out under the pressure of 0.1MPa-50MPa, preferably 1.0MPa-10MPa. The concentration of the catalyst in the reaction system can be from 0.01 μmol metal/L to 1000 μmol metal/L, preferably 0.1 μmol metal/L to 10 μmol metal/L.

The ethylene selective oligomerization catalytic system of the invention is used for ethylene oligomerization, especially ethylene trimerization and tetramerization.

Advantages and beneficial effects of the present invention:

The catalyst of the invention has high activity, high selectivity of target product 1-hexene+1-octene, and less 1-butene and 1-C10 ⁺ . The catalytic agent has the characteristics of simple synthesis, low cost, and long catalyst life. The mass percentage of C ₆ -C ₈ linear α-olefins in the product is >90%, and the mass percentage of C ₈ linear α-olefins is >60%.

detailed description

List 11 embodiments below, the present invention is described further, but not be used for limiting the scope of the present invention.

Example 1

1. Preparation of N-diphenylphosphino-2,6-diisopropylanilino (diphenylphosphino) dimethylsilane (C ₃₈ H ₄₃ NP ₂ Si)

(1) Preparation of diphenylphosphinolithium

Add dehydrated THF (200 mL) and diphenylphosphine (18.62 g, 0.1 mol) into a stirred 500 mL reactor fully replaced by N ₂ , stir well and cool to -80 °C with liquid nitrogen. Draw n-butyllithium hexane solution (41.6mL, 2.4mol/L) with a 100mL syringe, slowly add it dropwise to the above solution while stirring, keep stirring at -80°C for 1h, then rise to room temperature and continue stirring for 1 hour, and then vacuum The solvent was removed, n-hexane (100 mL) was added, stirred thoroughly and then filtered, and the obtained filtrate was vacuum-extracted at room temperature to obtain 18.82 g (0.098 mol, 98.6%) of the product.

(2) Preparation of diphenylphosphinodimethylchlorosilane (C ₁₄ H ₁₆ ClPSi)

In a glove box under _N2 atmosphere, dimethyldichlorosilane (6.45 g, 0.050 mol) was dissolved in dehydrated n-hexane (100 mL) and added to a 250 mL reactor, cooled to -35 ° C, vigorously stirred Get diphenylphosphinolithium (14.31g, 0.049mol), add in the above-mentioned solution several times in a small amount, after finishing, rise to room temperature naturally and continue to stir overnight, after filtering, vacuum remove the volatile components in the filtrate to obtain The yellow liquid was separated by distillation, and the fraction at 155°C-160°C was collected to obtain 11.33g (0.041mol, 83%) of a colorless liquid product.

(3) Preparation of N-diphenylphosphino-2,6-diisopropylaniline (C ₂₄ H ₂₈ NP)

In a glove box under _N2 atmosphere, the dehydrated 2,6-diisopropylaniline (7.09 g, 0.040 mol) was dissolved in dehydrated n-hexane (100 mL), cooled to -35 ° C, and Slowly add n-butyllithium n-hexane solution (17.1mL, 0.041mol, 2.4mol/L) dropwise into the above solution while stirring, continue to stir overnight after the dropwise addition, wash the filter cake twice with 20mL n-hexane after filtration, pump Dry to obtain 6.96 g (0.038 mol, 95%) of lithium salt of 2,6-diisopropylaniline, the intermediate product obtained was dispersed in n-hexane (100 mL), cooled to -35 ° C, diphenyl phosphorus chloride ( 8.38g, 0.038mol) was dissolved in 20mL of n-hexane, slowly added dropwise to the above solution, naturally raised to room temperature, stirred overnight, vacuum removed the volatile components, extracted the residue with 50mL toluene, filtered and vacuum dried the volatile components The fractions were washed twice with 20 mL of n-hexane, and sucked dry to obtain 10.8 g of product (0.030 mol, 78%).

(4) Preparation of N-diphenylphosphino-2,6-diisopropylanilino(diphenylphosphino)dimethylsilane (C ₃₈ H ₄₃ NP ₂ Si)

In a glove box under _N2 atmosphere, N-diphenylphosphino-2,6-diisopropylaniline (5.4 g, 0.015 mol) was dissolved in dehydrated n-hexane, cooled to -35 °C, Slowly add n-butyllithium n-hexane solution (6.3mL, 0.015mol, 2.4mol/L) dropwise into the above solution, continue stirring overnight after the dropwise addition, wash the filter cake twice with 20mL n-hexane after filtration, and drain to obtain N-diphenylphosphino-2,6-diisopropylaniline lithium salt 5.12g (0.014mol, 93%), the obtained intermediate product was dispersed in n-hexane (100mL), cooled to -35°C, distilled Phenylphosphinodimethylsilyl chloride (3.90g, 0.014mol) was dissolved in 20mL of n-hexane, and slowly added dropwise to the above lithium salt dispersion while stirring, naturally raised to room temperature, stirred overnight, and the volatile components were removed in a vacuum Finally, the residue was extracted with 50 mL of toluene, and after filtration, the volatile components were vacuum-extracted to obtain a yellow crude product, which was washed with 20 mL of n-hexane to obtain 6.64 g (0.011 mol, 75%) of a white product.

2. Preparation of catalyst

Added dehydrated methylcyclohexane (10 mL), DMAO (methylaluminoxane from trimethylaluminum removal) (0.57 g, 9.9 mmol) into a stirred 100 mL reactor fully replaced by _N2 , Triethylaluminum (0.38g, 3.3mmol), N-diphenylphosphino-2,6-diisopropylanilino(diphenylphosphino)dimethylsilane (41mg) (67.8μmol), CrCl ₃ ·(THF) ₃ (12 mg, 33 μmol), react at room temperature for 5 minutes and set aside.

3. Ethylene oligomerization

A 500mL autoclave was heated to vacuum for 2 hours, filled with ethylene after nitrogen replacement several times, cooled to a predetermined temperature, and dehydrated methylcyclohexane (200mL) and the above-mentioned catalyst were added. The oligomerization reaction was carried out at 40° C. and a pressure of 1 MPa. After 30 minutes of reaction, the temperature was lowered in an ice bath, the pressure was released, and the reaction was terminated with 10% acidified ethanol. 52.0 g of the oligomer product was obtained, and the catalyst activity was 3.15×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 2

With embodiment 1. The difference is that Ph ₁ to Ph ₄ are all dimethylphenyl groups. 50.2 g of the oligomer product was obtained, and the catalyst activity was 3.04×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 3

With embodiment 1. The difference is that Ph ₁ to Ph ₄ are all naphthyl groups. 51.3 g of the oligomer product was obtained, and the catalyst activity was 3.11×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 4

With embodiment 1. _The difference is that R1 and _R2 are methyl and cyclohexyl, respectively. 44.1 g of the oligomer product was obtained, and the catalyst activity was 2.67×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 5

With embodiment 1. _The difference is that R1 and _R2 are each phenyl. 25.6 g of the oligomer product was obtained, and the catalyst activity was 1.55×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 6

With embodiment 1. The difference is that _R3 is cyclopentyl. 29.4 g of the oligomer product was obtained, and the catalyst activity was 1.78×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 7

With embodiment 1. The difference is that _R3 is isopropyl. 37.5 g of the oligomer product was obtained, and the catalyst activity was 2.27×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 8

1. Preparation of N-diphenylphosphino-2,6-diisopropylanilino (diphenylphosphinomethyl) dimethylsilane (C ₃₉ H ₄₅ NP ₂ Si)

(1) with embodiment 1

(2) Preparation of diphenylphosphinomethyl chlorosilane (C ₁₄ H ₁₆ ClPSi)

In the glove box of _N2 atmosphere, diphenylmethylphosphine (10.01g, 0.050mol) and tetramethylethylenediamine (5.81g, 0.050mol) were dissolved in dehydrated n-hexane, cooled to - 35°C, slowly add n-butyllithium n-hexane solution (20.8mL, 0.05mol, 2.4mol/L) dropwise while stirring, naturally rise to room temperature after the addition, stir for 24 hours, filter and wash the filter cake with 10mL n-hexane After pumping to dryness, 8.66 g (0.042 mol, 84%) of a yellow solid was obtained, and dimethyldichlorosilane (5.42 g, 0.042 mol) was dissolved in dehydrated n-hexane (100 mL), cooled to -35 ° C, While stirring, add the above yellow solid into the n-hexane solution several times in small amounts, let it rise to room temperature naturally, stir overnight, filter and vacuum out the volatile components in the filtrate to obtain a yellow oily crude product, separate by distillation, and collect fractions at 158-165°C , to obtain 9.96 g (0.034 mol, 81%) of a colorless liquid product.

(3) with embodiment 1

(4) Preparation of N-diphenylphosphino-2,6-diisopropylanilino (diphenylphosphinomethyl) dimethylsilane (C ₃₉ H ₄₅ NP ₂ Si)

The preparation of N-diphenylphosphino-2,6-diisopropylanilide lithium salt was as in Example 1.

Disperse N-diphenylphosphino-2,6-diisopropylanilide lithium salt (5.51g, 0.015mol) in n-hexane (100mL), cool to -35°C, diphenylphosphinomethyl di Methylchlorosilane (4.39g, 0.015mol) was dissolved in 20mL of n-hexane, and slowly added dropwise to the above lithium salt dispersion while stirring, and naturally raised to room temperature, stirred overnight, and after the volatile components were removed in a vacuum, it was washed with 50mL of toluene The residue was extracted, and after filtration, the volatile components were vacuum-extracted to obtain a yellow crude product, which was washed with 20 mL of n-hexane to obtain 7.17 g (0.012 mol, 77%) of a white product.

2. Preparation of catalyst

Added dehydrated methylcyclohexane (10 mL), DMAO (methylaluminoxane from trimethylaluminum removal) (0.57 g, 9.9 mmol) into a stirred 100 mL reactor fully replaced by _N2 , Triethylaluminum (0.38g, 3.3mmol), N-diphenylphosphino-2,6-diisopropylanilino(diphenylphosphinomethyl)dimethylsilane (42mg) (67.8μmol), CrCl ₃ ·(THF) ₃ (12 mg, 33 μmol), reacted at room temperature for 5 min and then set aside.

3. Ethylene oligomerization

With embodiment 1. 57.3 g of the oligomerization product was obtained, and the catalyst activity was 3.47×10 ⁶ g oligomer/mol Cr·.h. The distribution of the oligomerization products is shown in Table 1.

Example 9

With embodiment 8. The difference is that the reaction temperature is 75°C. 66.2 g of the oligomer product was obtained, and the catalyst activity was 4.01×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 10

With embodiment 8. The difference is that the reaction pressure is 2MPa. 65.5 g of the oligomer product was obtained, and the catalyst activity was 3.97×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 11

With embodiment 8. The difference is that Ph ₁ to Ph ₄ are all o-methoxyphenyl groups. 46.4 g of the oligomer product was obtained, and the catalyst activity was 2.81×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

Example 12

With embodiment 8. The difference is that the reaction pressure is 20MPa. 92.1 g of the oligomerization product was obtained, and the catalyst activity was 5.58×10 ⁶ g oligomer/mol Cr.·h. The distribution of the oligomerization products is shown in Table 1.

Example 13

With embodiment 8. The difference is that the chromium compound is CrCl ₂ (THF) ₂ . 22.8 g of the oligomer product was obtained, and the catalyst activity was 1.38×10 ⁶ g oligomer/mol Cr·h. The distribution of the oligomerization products is shown in Table 1.

See Table 2 for the experimental conditions and catalyst activities of Examples 1-13.

Table 1 Comparison of carbon number distribution of oligomerization products

^a refers to the percentage content of 1-C ₆ ⁼ in C ₆ . ^b refers to the percentage content of 1-C ₈ ⁼ in C ₈ .

Table 2 Experimental conditions and catalyst activities of Examples 1-13.

Claims (9)

1. A catalyst component for selective oligomerization of ethylene is a heteroatom-containing ligand, characterized in that: it is a compound that meets the general formula (I), or contains two or more compounds that meet the general formula ( 1) the compound that structural unit shown in is linked together by group or chemical bond; The structure of general formula (I) is as follows: Among them, n is an integer, 0≤n≤4; Ph ₁ , Ph ₂ , Ph ₃ , Ph ₄ are selected from phenyl, substituted phenyl and their derivatives; R ₁ , R ₂ , R ₃ are selected from phenyl, chain Like alkyl, cyclic alkyl and their derivatives. 2. catalyst component according to claim 1, is characterized in that: preparation method comprises the steps: ①Preparation of diphenylphosphinolithium or diphenylphosphinopotassium: first disperse a certain amount of diphenylphosphine in an appropriate amount of n-hexane, then add n-butyllithium or potassium hydride dropwise at a certain temperature to prepare diphenylphosphine phosphinolithium or diphenylphosphinopotassium; ②Preparation of phosphinochlorosilane; dissolve a certain amount of dihydrocarbyl substituted dichlorosilane in an appropriate amount of n-hexane, cool down to a certain temperature, and then dissolve a small amount of diphenylphosphinolithium or diphenylphosphinopotassium solid several times Add it to the above solution, naturally rise to room temperature, stir overnight, and vacuum remove the volatile components in the filtrate after filtration to obtain a yellow oily crude product, which is separated by distillation to obtain a colorless or light yellow oily product; ③ Preparation of monophosphine amine intermediate: Dissolve a certain amount of primary amine compound in n-hexane, cool to a certain temperature, slowly add a certain amount of n-butyllithium n-hexane solution into the above solution, naturally rise to room temperature, stir Overnight, filter and wash with an appropriate amount of n-hexane, then drain the filter cake to obtain the lithium salt of the primary amine compound, disperse the lithium salt of the primary amine compound in an appropriate amount of n-hexane, cool to a certain temperature, and replace a certain amount of dihydrocarbyl with chlorine The n-hexane solution of phosphorus compound was slowly added dropwise to the above lithium salt, naturally raised to room temperature, stirred overnight, after the volatile components were vacuumed off, the residue was extracted with an appropriate amount of toluene, and the volatile components were vacuum pumped after filtration to obtain The yellow crude product was washed with an appropriate amount of n-hexane to obtain a white or light yellow product; ④ Preparation of ligand: Dissolve a certain amount of monophosphine amine intermediate in dehydrated n-hexane, cool to a certain temperature, slowly add a certain amount of n-butyllithium n-hexane solution into the above solution, and dropwise Then naturally rise to room temperature, continue to stir overnight, wash the filter cake with a certain amount of n-hexane after filtration, and obtain monophosphine amine lithium salt after drying, then disperse the modified lithium salt in n-hexane, and at a certain temperature, a certain amount of The phosphinochlorosilane was slowly added dropwise to the above solution, naturally raised to room temperature, stirred overnight, the volatile components were vacuumed off, the residue was extracted with an appropriate amount of toluene, and the volatile components were vacuum pumped after filtration to obtain the ligand product . 3. A catalyst for selective oligomerization of ethylene, characterized in that it comprises at least one heteroatom-containing ligand as claimed in claim 1, a transition metal compound, and an organometallic compound activator. 4. The catalyst according to claim 3, characterized in that: the transition metal compound is a compound of chromium, molybdenum, tungsten, titanium, tantalum, vanadium, zirconium, iron, nickel or palladium. 5. The catalyst according to claim 3, characterized in that: the organometallic compound activator is an alkylaluminum compound, an aluminoxane compound, an organoboron compound, an organic salt, an inorganic acid or an inorganic salt; or they A mixture of several of them. 6. The catalyst according to claim 3, characterized in that: in the catalyst, the molar ratio of the heteroatom-containing ligand, the transition metal compound, and the organometallic compound activator is 1:0.5-100:0.1-5000. 7. The catalyst according to claim 3, characterized in that: the preparation method is: pre-mixing heteroatom-containing ligands, transition metal compounds, and organometallic compound activators; or directly adding to the reaction system for in-situ synthesis . 8. the application of a kind of catalyst described in claim 3 in ethylene oligomerization. 9. The application according to claim 8, characterized in that: the reaction is carried out in an inert solvent, the reaction temperature is 0°C to 200°C, and the reaction pressure is 0.1MPa to 50MPa to obtain ethylene selective oligomerization products.