CN117983304A

CN117983304A - Catalyst containing tetraphosphine ligand for ethylene selective tetramerization and preparation method and application thereof

Info

Publication number: CN117983304A
Application number: CN202211351163.5A
Authority: CN
Inventors: 张军; 赵兴; 孔维欢; 周涛; 左静; 王继贺
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2022-10-31
Filing date: 2022-10-31
Publication date: 2024-05-07

Abstract

The invention relates to a catalyst containing tetraphosphine ligand for ethylene selective tetramerization, a preparation method and application thereof, wherein the catalyst comprises ligand, transition metal compound and activator, and the chemical structural formula of the ligand is shown as the following formula (I): Wherein the groups R ₁ and R ₂ are each independently selected from hydrogen, halogen, alkyl; the groups R ₃ to R ₁₀ are each independently selected from alkyl, alkenyl or aromatic groups. The catalyst is used for ethylene selective tetramerization reaction to generate 1-octene, and the reaction is carried out in inert solvent. Compared with the prior art, the method has the advantages of low cocatalyst consumption, higher activity and 1-octene selectivity, high total selectivity of 1-hexene and 1-octene, low polymer content and the like.

Description

Catalyst containing tetraphosphine ligand for ethylene selective tetramerization and preparation method and application thereof

Technical Field

The invention relates to the technical field of ethylene oligomerization, in particular to a catalyst containing tetraphosphine ligand for ethylene selective tetramerization, and a preparation method and application thereof.

Background

Linear alpha-olefin (LAO) is used as an important chemical raw material for preparing lubricating oil, surfactant and the like, wherein 1-hexene and 1-octene are indispensable comonomers in the synthesis of Linear Low Density Polyethylene (LLDPE) and High Density Polyethylene (HDPE) (the comonomer content in LLDPE is generally 8-10%, and the comonomer content in HDPE is 1-2%). The traditional ethylene oligomerization catalysis mainly follows Cossee-Arlman mechanism, namely ethylene molecules are inserted into the metal center of the catalyst to linearly grow, the obtained linear alpha-olefin is normally distributed, and the linear alpha-olefin needs to be separated and purified according to the needs in industrial application, and represents a system such as titanium system, zirconium system, iron system and the like. The chromium-catalyzed ethylene oligomerization mainly follows a metal ring mechanism, so that the produced alpha-olefin is in Schulz-Flory distribution, and the products at the peak have higher proportion.

As research continues, it has been found that the structure of the catalyst plays a key role in the product distribution, in other words that the framework and substituent changes of the ligand determine the selective oligomerization effect of ethylene. In recent years, research in this area has focused on the mechanism of ethylene selective oligomerization catalysis and ligand design, with some important achievements. In 2002, british Petroleum reported that PNP ligands with the structure of PAr ₂N(R)PAr₂ (Ar is ortho methoxy substituted aryl) were used for chromium catalyzed high selectivity ethylene trimerization to 1-hexene (chem. Commun.2002, 858-859). In 2004, ethylene tetramerization was successfully achieved by Sasol company modified with substituents using the PNP ligand/chromium catalytic system described above, with 1-octene selectivities up to 67.5% (J.Am. Chem. Soc.2004,126, 14712). In 2008, sasol company synthesizes a series of carbon bridged biphosphine ligands for catalyzing ethylene selective tetramer (J.mol. Catalyst. A: chem.2008,283, 114), wherein the phenyl bridged biphosphine ligand has relatively good catalytic effect, the activity can reach 2240kg/g Cr/h, but the 1-octene selectivity can only reach 56.8%, and the polymer content in the product is higher (0.9%). MAO or MMAO is adopted as a cocatalyst in the ethylene selective oligomerization system, and the cocatalyst has large dosage and high price, and is not beneficial to industrial production; in addition, the homogeneous catalyst is easy to be subjected to bimolecular deactivation, the catalyst activity is inhibited, and the deactivated catalyst can catalyze ethylene to polymerize to generate high polymers, so that the normal operation of equipment is affected.

Disclosure of Invention

The invention aims to overcome at least one of the defects in the prior art and provide a catalyst for ethylene selective tetramerization containing tetraphosphine ligand, which has the advantages of low cocatalyst consumption, higher activity and 1-octene selectivity, high total selectivity of 1-hexene and 1-octene and low polymer content, and a preparation method and application thereof.

The aim of the invention can be achieved by the following technical scheme:

In order to reduce the consumption of a cocatalyst and improve the activity of a catalytic system, four P-RR 'groups (R and R' can be the same or different and represent R ₃-R₁₀ and are respectively and independently selected from alkyl, alkenyl or aromatic groups) are creatively introduced at the 1,2,4 and 5 positions of phenyl groups, and the obtained ligand has two coordination centers, so that the bimolecular deactivation reaction can be effectively inhibited, the activity of the catalyst is greatly improved, the content of a polymer is reduced, and the consumption of MMAO is reduced. Meanwhile, the invention introduces sterically adjustable alkyl and ortho-halogenated aryl on the phosphorus atom. By introducing ortho-halogenated aryl and alkyl with smaller steric hindrance, the invention successfully improves the 1-octene selectivity of the catalytic system to 75.6 percent, improves the total selectivity of 1-hexene and 1-octene to 95.8 percent, and further improves the catalytic activity, wherein the highest catalytic activity can reach 4680kg/g Cr/h, and the specific scheme is as follows:

a catalyst for ethylene selective tetramerization containing tetraphosphine ligand, which comprises ligand, transition metal compound and activator, wherein the chemical structural formula of the ligand is shown as the following formula (I):

In the method, in the process of the invention,

The groups R ₁ and R ₂ are each independently selected from hydrogen, halogen or alkyl;

The groups R ₃ to R ₁₀ are each independently selected from alkyl, alkenyl or aromatic groups.

Further, the alkyl group is a C ₁-C₃₀ alkyl group, specifically including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, cyclopentyl, n-hexyl, sec-hexyl, isohexyl, cyclohexyl, n-heptyl, cycloheptyl, n-octyl, n-decyl, 2-methylcyclopentyl, or 2, 6-dimethylcyclohexyl.

Further, the alkenyl is C ₁-C₃₀ alkenyl, specifically comprises vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-2-butenyl, 2-methyl-1-butenyl, 3-methyl-2-butenyl, 5-hexenyl, 2-cyclohexenyl, 3-cyclohexenyl or 2-methyl-2-cyclohexenyl; the halogen is fluorine, chlorine, bromine or iodine.

Further, the aromatic group is aryl of C ₄-C₃₀ and its derivatives, specifically including phenyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, 2, 6-difluorophenyl, 2, 5-difluorophenyl, 2, 4-difluorophenyl, 2, 3-difluorophenyl, 3, 4-difluorophenyl, 3, 5-difluorophenyl, 2, 6-dichlorophenyl, 2, 5-dichlorophenyl, 2, 4-dichlorophenyl, 2, 3-dichlorophenyl, 3, 4-dichlorophenyl, 3, 5-dichlorophenyl, p-ethylphenyl, o-ethylphenyl, m-ethylphenyl, 2, 4-dimethylphenyl, 2, 4-diisopropylphenyl, 2, 4-di-tert-butylphenyl, 2, 6-dimethylphenyl, 2, 6-diisopropylphenyl, 3, 5-di-tert-butylphenyl, 2,4, 6-trimethylphenyl, naphthyl, anthracenyl, biphenyl, 7-fluoro-1-naphtyl, 8-chloro-1-anthracenyl, 8-chloro-1-chloro-8-anthracenyl, 1-chloro-8-chloro-1-anthracenyl;

Further, at least one of the groups R ₃ to R ₁₀ is not phenyl.

The transition metal in the catalyst system of the present invention may be a transition metal compound commonly used in the art, and a metal atom in the transition metal compound is a metal active center, which plays an important role in the catalytic process. Further, the transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, nickel or palladium; more preferably, the transition metal in the transition metal compound is selected from chromium, in particular, the corresponding transition metal compound is any chromium compound that enables oligomerization, and the optional chromium compound includes compounds of the general formula CrR _n, wherein R _n is an organic anion or a neutral molecule, R _n generally contains 1 to 15 carbon atoms, n is an integer from 0 to 6, and the valence of Cr is from 0 to 6. The specific R _n group is an organic matter containing carboxyl, beta-diketone and hydrocarbon groups or other groups. From the viewpoint of ease of dissolution and handling, preferred chromium compounds include one of chromium trichloride-tris (tetrahydrofuran) complex, (benzene) chromium tricarbonyl, chromium (III) octoate, chromium hexacarbonyl, chromium (III) acetylacetonate, chromium (III) naphthenate, chromium (III) 2-ethylhexanoate, chromium (III) acetate, chromium (III) 2, 6-tetramethylheptanedione and chromium (III) chloride. Preferably, the chromium compound is selected from chromium trichloride-tris (tetrahydrofuran) complex, chromium (III) acetylacetonate, chromium (III) 2-ethylhexanoate.

The activator in the catalyst system of the present invention acts as an activator in the catalyst system. Activators useful in the present invention may be any compound that when mixed with a ligand and a transition metal compound forms an active catalyst. The activators may be used alone or in combination. The activator comprises an alkyl aluminum compound, an aluminoxane compound or an organoboron compound; the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100): 1; the mole ratio of the activator to the transition metal element in the transition metal compound is (1-10000): 1. Further, the aluminoxane compound specifically comprises a modified methylaluminoxane MMAO-3A; the mole ratio of the activator to the transition metal element in the transition metal compound is (250-500): 1.

Further, the activator includes an alkyl aluminum compound, an aluminoxane compound, or an organoboron compound.

Further, the activator comprises one or a mixture of several of alkyl aluminum compound, aluminoxane compound, organic boron compound, inorganic acid or inorganic salt.

Specifically, the activator may be an alkylaluminum compound, which may be various trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum or tri-n-octylaluminum; the alkylaluminum compound may also be an alkylaluminum halide, alkylaluminum hydride or alkylaluminum sesquichloride, such as diethylaluminum chloride (AlEt ₂ Cl) and triethylaluminum chloride (Al ₂Et₃Cl₃).

Specifically, the activator may be an aluminoxane compound, which can be generally prepared by mixing water with an alkylaluminum compound (e.g., trimethylaluminum). The aluminoxane oligomer compound prepared may be a linear compound, a cyclic compound, a cage compound, or a mixture thereof. Suitable aluminoxane compounds can be selected from Methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, modified aluminoxane, methylaluminoxane DMAO from which volatile components have been removed, and the like.

Specifically, suitable boron compounds may include boroxine, triethylborane, triphenylborane, tris (pentafluorophenyl) borane, and the like. The organoboron compound may be used in a form of a mixture with the organoaluminum compound.

Preferably, the activator may be selected from Methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane and Modified Methylaluminoxane (MMAO).

Further, the aluminoxane compound specifically comprises a modified methylaluminoxane MMAO-3A.

Further, the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100): 1, preferably (0.1-10): 1, more preferably (0.5-2): 1;

The molar ratio of the activator to the transition metal element in the transition metal compound is (1-10000): 1, preferably (1-2000): 1, more preferably (100-1000): 1, and finally preferably (200-400): 1.

A process for preparing a catalyst for the selective tetramerization of ethylene containing a tetraphosphine ligand as described above, which process comprises: the ligand, the transition metal compound and the activator are pre-mixed or directly added into a reaction system for in-situ synthesis, thus obtaining the ethylene selective tetramerization catalyst containing tetraphosphine ligand.

In some embodiments, the ligand of formula (I), the transition metal compound, and the activator may be mixed simultaneously or in any order in the presence or absence of a solvent to provide an active catalyst. The mixing of the catalyst components can be carried out at a temperature of from-20 to 250 ℃ and the presence of the olefin typically exhibits a protective effect during the mixing of the catalyst components, thereby providing improved catalytic performance. Further, the mixing of the catalyst components may be performed at a temperature in the range of about 20-100 ℃.

In some embodiments, the detachable metal-ligand complex may be prepared in situ from the transition metal compound and the ligand of formula (I). The metal-ligand complex is then added to the reaction medium. Alternatively, the chromium compound and the ligand may be separately added to the reactor, thereby preparing the chromium-ligand complex in situ. In situ preparation of the complex means that the complex is prepared in the medium in which the catalytic reaction takes place and finally the activator is added.

Use of a catalyst for the selective tetramerisation of ethylene containing a tetraphosphine ligand as described above, for the selective tetramerisation of ethylene to 1-octene in an inert solvent at a temperature of 0 to 200 ℃ and a pressure of 10 to 5000psig, the concentration of transition metal in the transition metal compound in the inert solvent being 0.01 to 10000 mu mol/L; further, the temperature of the reaction is 40-80 ℃; the pressure is 300-500psig.

Further, the reaction is carried out in an inert solvent at a temperature of 0 to 200 ℃, preferably 10 to 120 ℃, more preferably 15 to 100 ℃, further preferably 20 to 80 ℃, and finally preferably 20 to 50 ℃, at a reaction pressure of 10 to 5000psig, preferably 100 to 2000psig, more preferably 300 to 1000psig, and finally preferably 400 to 600psig, and a concentration of the transition metal in the transition metal compound in the inert solvent of 0.01 to 10000. Mu. Mol/L, preferably 1 to 500. Mu. Mol/L, and more preferably 0.1 to 10. Mu. Mol/L.

The inert solvent comprises one or more of alkane, arene, alkene or ionic liquid. Typical solvents include, but are not limited to, benzene, toluene, xylene, cumene, chlorobenzene, dichlorobenzene, fluorobenzene, n-heptane, n-hexane, methylcyclohexane, cyclohexane, 1-hexene, 1-octene, and the like, with toluene, methylcyclohexane being preferred.

Compared with the prior art, the invention has the following advantages:

(1) According to the invention, four P-RR 'groups (R and R' can be the same or different and represent R ₃-R₁₀ and are respectively and independently selected from alkyl, alkenyl or aromatic groups) are creatively introduced at the 1,2, 4 and 5 positions of phenyl, and the obtained ligand has two coordination centers, so that the bimolecular deactivation reaction can be effectively inhibited, the activity of the catalyst is greatly improved, the content of the polymer is reduced, the MMAO consumption is reduced, and the production cost is reduced;

(2) The invention introduces sterically adjustable alkyl and ortho-position halogenated aryl groups on the phosphorus atom. By introducing ortho-halogenated aryl and alkyl with smaller steric hindrance, the invention effectively improves the 1-octene selectivity, the total selectivity of 1-hexene and 1-octene and the catalytic activity of the catalytic system.

Detailed Description

The following describes in detail the examples of the present invention, which are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of protection of the present invention is not limited to the following examples. The term "mass% is not specifically defined but may be regarded as mass%.

A catalyst containing tetraphosphine ligand for ethylene selective tetramerization and a preparation method and application thereof, wherein the preparation method comprises the following steps: the ligand, the transition metal compound and the activator are pre-mixed or directly added into a reaction system for in-situ synthesis, thus obtaining the ethylene selective tetramerization catalyst containing tetraphosphine ligand. The catalyst is used for ethylene selective tetramerization reaction to generate 1-octene, the reaction is carried out in an inert solvent, the temperature of the reaction is 0-200 ℃, the pressure is 10-5000psig, and the concentration of transition metal in the transition metal compound in the inert solvent is 0.01-10000 mu mol/L; the inert solvent comprises one or more of alkane, arene, alkene or ionic liquid. In some embodiments, the temperature of the reaction is 40-80 ℃; the pressure is 300-500psig.

Wherein the chemical structural formula of the ligand is shown as the following formula (I):

Wherein the groups R ₁ and R ₂ are each independently selected from hydrogen, halogen, alkyl; the groups R ₃ to R ₁₀ are each independently selected from alkyl, alkenyl or aromatic groups. At least one of the radicals R ₃ to R ₁₀ is not phenyl.

The transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, nickel or palladium; the activator comprises an alkyl aluminum compound, an aluminoxane compound or an organoboron compound; the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100): 1; the mole ratio of the activator to the transition metal element in the transition metal compound is (1-10000): 1. The aluminoxane compounds specifically include modified methylaluminoxane MMAO-3A; the mole ratio of the activator to the transition metal element in the transition metal compound is (250-500): 1.

Example 1

The preparation of complex 1 is as follows:

(1) Preparation of (2-F-Ph) ₂ PCl

Magnesium powder (0.88 g,36 mmol) was placed in a Schlenk reaction tube, tetrahydrofuran (10 mL) was added under nitrogen protection, 5 drops of 1, 2-dibromoethane were added dropwise thereto, after 3 minutes of reaction, a solution of o-bromofluorobenzene (5.25 g,30 mmol) in tetrahydrofuran (40 mL) was slowly added at 0℃and reacted for 1 hour, and a solution of o-fluorophenyl magnesium bromide (30 mmol) in tetrahydrofuran was obtained as a gray black color by filtration. Phosphorus trichloride (2.06 g,15 mmol) was dissolved in tetrahydrofuran (10 mL), cooled to-78deg.C, to which was slowly added a tetrahydrofuran solution (50 mL) of the above-prepared o-fluorophenylmagnesium bromide (30 mmol), and after completion of the dropwise addition, slowly warmed to room temperature and stirred for 5 hours, the reaction was completed, the solvent was drained, diethyl ether (40 mL) was dissolved, filtered anhydrous and anaerobic, and the solvent was drained to give a pale yellow oily product which was directly used for the next reaction.

(2) Preparation of ligand L ¹

In a 50mL Schlenk flask, which was filled with argon, 1, 4-dibromo-2, 5-difluorobenzene (7.5 mmol,2.0 g) and 30mL redistilled tetrahydrofuran were added, stirred and cooled to-95℃and lithium diisopropylamide (6.0 mL,2.5M in hexane, 15.0 mmol) was added dropwise to the solution, stirred at this temperature for 10 minutes, diphenyl phosphorus chloride (15 mmol,3.3 g) was added, the reaction was completed at this temperature for 1h, and the mixture was allowed to react overnight at room temperature, water (20 mL) and methylene chloride (20 mL. Times.3) were added, extraction, organic phase drying filtration, vacuum drying of the filtrate, and separation and purification of the silica gel column to give an orange solid product (3.3 g, 90.0%). In a 50mL Schlenk flask filled with argon, the above orange solid product and redistilled tetrahydrofuran (30 mL) were added, stirred and cooled to-78deg.C, n-butyllithium (5.4 mL,2.5M in hexane, 13.5 mmol) was added dropwise, stirred at this temperature for 1h, the above prepared (2-F-Ph) ₂ PCl (15 mmol) was added dropwise, reacted at this temperature for 1h after the addition, moved to room temperature overnight, added with water (20 mL) and dichloromethane (20 mL. Times.3), extracted, dried organic phase filtered, the filtrate was dried in vacuo, and the silica gel column was separated and purified to give a yellow solid product L¹(4.0g,67.0％).¹H NMR(400MHz,CDCl₃)δ7.13-7.15(m,12H),7.21-7.22(m,8H),7.28-7.32(m,2H),7.44-7.47(m,12H),7.65-7.68(m,4H).

(3) Preparation of Complex 1

In a dry and argon filled Schlenk reaction tube, ligand L ¹ (443.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 577.9mg (0.43 mmol, 86.0%) of a blue powder.

Example 2

The preparation of complex 2 is as follows:

(1) Preparation of (2-F-Ph) (Ph) PCl

Phenyl phosphorus dichloride (1.25 g,7 mmol) was dissolved in tetrahydrofuran (10 mL), cooled to-78deg.C, and to this was slowly added a tetrahydrofuran solution (10 mL) of the o-fluorophenyl magnesium bromide (7 mmol) prepared above, after the addition was completed, slowly warmed to room temperature and stirred for 5 hours, the reaction was complete, the solvent was drained, diethyl ether (40 mL) was dissolved, filtered anhydrous and anaerobic, and the solvent was drained to give a pale yellow oily product.

(2) Preparation of ligand L ²

Preparation of reference ligand L ¹ Using (2-F-Ph) (Ph) PCl (15.0 mmol) instead of (2-F-Ph) ₂ PCl gave the product as a colourless oil L²(4.8g,83.7％).¹H NMR(400MHz,CDCl₃)δ7.13-7.15(m,14H),7.21-7.22(m,4H),7.29-7.32(m,2H),7.44-7.47(m,18H),7.46-7.67(m,2H).

(3) Preparation of Complex 2

In a dry and argon filled Schlenk reaction tube, ligand L ² (425.0 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 555.9mg (0.43 mmol, 85.0%) of a blue powder.

Example 3

The preparation of complex 3 is as follows:

(1) Preparation of ligand L ³

Preparation of reference ligand L ¹ Using diethyl phosphorus chloride (1.1 g,15.0 mmol) instead of (2-F-Ph) ₂ PCl gave the product as a yellow oil L³(3.2g,75.2％).¹H NMR(400MHz,CDCl₃)δ0.98-1.02(m,12H),1.65-1.68(m,8H),7.14-7.16(m,8H),7.33-7.37(m,2H),7.44-7.47(m,12H).

(2) Preparation of Complex 3

In a dry and argon filled Schlenk reaction tube, ligand L ³ (311.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with anhydrous and oxygen-free solution, washed with n-hexane (5 mL. Times.3), and dried to give 426.6mg (0.40 mmol, 79.0%) of a blue powder.

Example 4

The preparation of complex 4 is as follows:

(1) Preparation of (Ph) (Et) PCl

Phenyl phosphorus dichloride (1.79 g,10 mmol) was added to a dry nitrogen filled 50mL Schlenk tube, dissolved by adding 10mL tetrahydrofuran, then the solution was cooled to-78 ℃, ethyl magnesium chloride (10.0mL,1.0M in THF,10mmol) was slowly added thereto, after the addition was completed, the reaction was continued at that temperature for 30 minutes, then allowed to stand for 8 hours at room temperature, and after the completion of the reaction, it was used without purification.

(2) Preparation of ligand L ⁴

Preparation of reference ligand L ¹ Using (Ph) (Et) PCl (15.0 mmol) instead of (2-F-Ph) ₂ PCl, a yellow solid product was obtained L⁴(3.4g,69.2％).¹H NMR(400MHZ,CDCl₃)δ0.90-1.02(m,6H),1.31-1.61(m,4H),7.10-7.22(m,12H),7.30-7.38(m,2H),7.41-7.44(m,14H),7.46-7.51(m,4H).

(3) Preparation of Complex 4

In a dry and argon filled Schlenk reaction tube, ligand L ⁴ (359.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with anhydrous and oxygen-free solution, washed with n-hexane (5 mL. Times.3), and dried to give 464.5mg (0.40 mmol, 79.0%) of a blue powder.

Example 5

The preparation of complex 5 is as follows:

(1) Preparation of ligand L ⁵

Preparation of reference ligand L ¹ Using (Ph) (Et) PCl (15.0 mmol) instead of diphenylphosphorus chloride and (Ph) (Et) PCl (15.0 mmol) instead of (2-F-Ph) ₂ PCl gave the product as a pale yellow solid L⁵(3.6g,80.0％).¹H NMR(400MHZ,CDCl₃)δ0.93-1.02(m,12H),1.42-1.57(m,8H),7.12-7.19(m,8H),7.25-7.38(m,2H),7.41-7.46(m,12H).

(2) Preparation of Complex 5

In a dry and argon filled Schlenk reaction tube, ligand L ⁵ (311.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 415.8mg (0.39 mmol, 77.0%) of a blue powder.

Example 6

The preparation of complex 6 is as follows:

(1) Preparation of ligand L ⁶

Preparation of reference ligand L ¹ Using (2-F-Ph) (Ph) PCl (15.0 mmol) instead of diphenylphosphorus chloride and diethylphosphorus chloride (15 mmol) instead of (2-F-Ph) ₂ PCl gave the product as a pale yellow solid L⁶(2.2g,49.2％).¹H NMR(400MHz,CDCl₃)δ7.13-7.15(m,14H),7.21-7.22(m,4H),7.29-7.32(m,2H),7.44-7.47(m,18H),7.46-7.67(m,2H).

(2) Preparation of Complex 6

In a dry and argon filled Schlenk reaction tube, ligand L ⁶ (329.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 446.4mg (0.40 mmol, 79.0%) of a blue powder.

Example 7

The preparation of complex 7 is as follows:

(1) Preparation of ligand L ⁷

Preparation of reference ligand L ⁶ Using diisopropylphosphorus chloride (15.0 mmol) instead of diethylphosphorus chloride gives the product as a yellow oil L⁷(3.7g,79.2％).¹H NMR(400MHZ,CDCl₃)δ0.88-1.02(m,24H),1.45-1.72(m,4H),7.11-7.17(m,4H),7.19-7.25(m,2H),7.32-7.39(m,2H),7.41-7.49(m,6H),7.65-7.72(m,2H).

(2) Preparation of Complex 7

In a dry and argon filled Schlenk reaction tube, ligand L ⁷ (343.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 460.5mg (0.40 mmol, 80.5%) of a blue powder.

Example 8

The preparation of complex 8 is as follows:

(1) Preparation of ligand L ⁸

Preparation of reference ligand L ⁶ Using (Ph) (Et) PCl (15.0 mmol) instead of diethylphosphorus chloride gives the product as a yellow oil L⁸(2.6g,50.9％).¹H NMR(400MHz,CDCl₃)δ0.86-1.04(m,6H),1.37-1.51(m,4H),7.13-7.19(m,14H),7.33-7.49(m,14H),7.62～7.71(m,2H).

(2) Preparation of Complex 8

In a dry and argon filled Schlenk reaction tube, ligand L ⁸ (377.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 545.4mg (0.45 mmol, 90.2%) of a blue powder.

Example 9

The preparation of complex 9 is as follows:

(1) Preparation of ligand L ⁹

In a Schlenk reaction tube which is dried and filled with argon, small pieces of sodium (920.0 mg,40 mmol) and redistilled tetrahydrofuran (50 mL) are added, diphenyl phosphorus chloride (4.4 g,20 mmol) is slowly added dropwise thereto, heated under reflux for 6 hours, excess sodium is removed by anhydrous anaerobic filtration, 1,2,4, 5-tetrafluorobenzene (0.3 g,2 mmol) is slowly added dropwise to the solution, after the addition is completed, the temperature is raised and reflux is carried out overnight, water (20 mL) and methylene chloride (20 mL. Times.3) are added, extraction and organic phase drying filtration are carried out, the filtrate is dried under vacuum, and silica gel column separation and purification are carried out to obtain yellow solid products L ⁹(1.1g,65.0％).¹H NMR(CDCl₃) delta 7.19-7.13 (m, 8H), 7.07 (m, 16H) and 6.96-6.89 (m, 18H).

(2) Preparation of Complex 9

In a dry and argon filled Schlenk reaction tube, ligand L ⁹ (407.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (374.7 mg,1.0 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 586.4mg (0.46 mmol, 92.2%) of a blue powder.

Example 10

The preparation of complex 10 is as follows:

(1) Preparation of ligand L ¹⁰

O-bromoiodobenzene (2.83 g,10.0 mmol), diphenylphosphine (1.86 g,10.0 mmol) and triethylamine (1.11 g,11.0 mmol) were sequentially added to a dry nitrogen-filled 50mL Schlenk tube, pd (PPh ₃)₄) (58 mg,0.05 mmol) and triethylamine (1.11 g,11.0 mmol) and then 10mL toluene was added thereto to dissolve the starting material to give a bright yellow solution, the solution was stirred at 85℃for 17 hours, cooled to room temperature after the reaction was completed, 10mL water was added thereto and stirred for 5 minutes, the aqueous phase was extracted with diethyl ether (3X 10 mL), the organic phase was dried with anhydrous magnesium sulfate, filtered, and the solvent in the organic phase was removed under reduced pressure to give a crude product, further purified by silica gel column chromatography to give 3.1g (9.1 mmol, 91.2%) of a white solid product, followed by adding the above white solid product and tetrahydrofuran (20 mL Schlenk tube, cooling was then carried out at 85℃and then cooling to 5mL water, and then dropwise adding dropwise to 2.78 mL of dry solid phase after the reaction was completed, and then 10mL of dry solid was added dropwise to 3.8 mL of dry phase, and then dropwise added to dry acetone (0.8 mmol) was obtained after the reaction was completed, and three-phase was further purified).

(2) Preparation of Complex 10

In a dry and argon filled Schlenk reaction tube, ligand L ¹⁰ (223.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (187.3 mg,0.5 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resultant solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried by suction to give 287.6mg (0.43 mmol, 85.2%) of a blue powder.

Example 11

The preparation of complex 11 is as follows:

(1) Preparation of ligand L ¹¹

O-bromoiodobenzene (2.83 g,10.0 mmol), diphenylphosphine (1.86 g,10.0 mmol) and triethylamine (1.11 g,11.0 mmol) were sequentially added to a dry nitrogen-filled 50mL Schlenk tube, pd (PPh ₃)₄) (58 mg,0.05 mmol) and triethylamine (1.11 g,11.0 mmol) and then 10mL toluene was added thereto to dissolve the starting material to give a bright yellow solution, the solution was stirred at 85℃for 17 hours, cooled to room temperature after the reaction was completed, 10mL of water was added thereto and stirred for 5 minutes, the aqueous phase was extracted with diethyl ether (3X 10 mL), the organic phase was dried with anhydrous magnesium sulfate, filtered, and the solvent in the organic phase was removed under reduced pressure to give a crude product, further purified by silica gel column chromatography to give 3.1g (9.1 mmol, 91.2%) of a white solid product, which was added to a dry nitrogen-filled 50mL Schlenk tube, followed by cooling to 85℃and then by dropwise addition of 5mL of water to give a dry solution (5 mL of ethyl ether, 0.6 mmol) and then dropwise addition of dropwise lithium chloride to the dry solid (10.5 mmol) was further purified).

(2) Preparation of Complex 11

In a dry and argon filled Schlenk reaction tube, ligand L ¹¹ (175.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (187.3 mg,0.5 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 261.4mg (0.45 mmol, 90.3%) of a blue powder.

Example 12

The preparation of complex 12 is as follows:

(1) Preparation of ligand L ¹²

Preparation of reference ligand L ¹¹ Using (Ph) (Et) PCl (10.0 mmol) instead of diethylphosphorus chloride, a white solid product was obtained L¹²(2.3g,62.5％).¹H NMR(400MHz,CDCl₃)δ0.86-1.04(m,3H),1.37-1.52(m,2H),7.13-7.19(m,8H),7.40-7.51(m,11H).

(2) Preparation of Complex 12

In a dry and argon filled Schlenk reaction tube, ligand L ¹¹ (199.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (187.3 mg,0.5 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After completion of the reaction, the resulting solid was filtered off with anhydrous and oxygen-free solution, washed with n-hexane (5 mL. Times.3), and dried to give 259.0mg (0.41 mmol, 82.6%) of a blue powder.

Example 13

The preparation of complex 13 is as follows:

(1) Preparation of (2-F-Ph) (Ph) PH

(2-F-Ph) (Ph) PCl (2.4 g,10 mmol) was added dropwise to a solution of lithium aluminum hydride (152.0 mg,4 mmol) in diethyl ether (15 mL) at-78deg.C, stirred for 30 min, then warmed to room temperature and stirred overnight, the mixture was pumped to dryness to solvent, then n-hexane (10 mL) and diethyl ether (3 mL) were added to dissolve, and the filtrate was filtered and pumped under reduced pressure to give crude oil, which was used directly in the next step.

(2) Preparation of ligand L ¹³

Preparation of reference ligand L ¹¹ Using (2-F-Ph) (Ph) PH (10.0 mmol) in place of diphenylphosphorus gives the product as a white solid L¹³(2.6g,70.6％).¹H NMR(400MHz,CDCl₃)δ0.86-1.04(m,6H),1.37-1.72(m,4H),7.11-7.28(m,7H),7.41-7.50(m,5H),7.62-7.71(m,1H).

(3) Preparation of Complex 13

In a dry and argon filled Schlenk reaction tube, ligand L ¹³ (184.1 mg,0.5 mmol) and CrCl ₃(THF)₃ (187.3 mg,0.5 mmol) were added, and redistilled toluene (10 mL) was added and heated to 80℃for 4h. After the completion of the reaction, the resulting solid was filtered off with no water and oxygen, washed with n-hexane (5 mL. Times.3), and dried to give 254.6mg (0.43 mmol, 85.3%) of a blue powder.

Example 14

A catalyst containing tetraphosphine ligand for selectively tetramerizing ethylene, its preparation method and application, the steps are as follows:

(1) Preparation of the catalyst

In a Schlenk reaction tube which was dried and filled with argon, complex 1 (1.08 mg, 0.8. Mu. Mol) and anhydrous methylcyclohexane (20 ml) were added, and after stirring for 5 minutes, modified methylaluminoxane MMAO-3A (0.4 mmol,1.12 mol/L) was added and reacted at room temperature for 5 minutes for further use.

(2) Oligomerization of ethylene

The 350mL stainless steel high-pressure gas reaction kettle is vacuumized on an oil bath at 120 ℃ for 3 hours to ensure the anhydrous and anaerobic environment of the reaction kettle, then cooled to the reaction temperature, and the kettle is internally ventilated for three times by ethylene gas. Then immediately sucking the prepared catalyst solution by a dry glass injector, injecting the catalyst solution into a high-pressure reaction kettle, sealing the reaction kettle, starting stirring, introducing ethylene gas, regulating the pressure to 500psig, and stirring at 60 ℃ for reaction for 30 minutes. After the reaction is finished, an ethylene gas supply valve is closed, the temperature is cooled to 0 ℃, the pressure is released, the reaction kettle is opened, and quantitative internal standard nonane is added and stirred uniformly. The reaction was then quenched with 10wt% aqueous HCl for about 30mL and the organic phase was filtered and analyzed by GC. The remaining mixture in the reaction vessel was filtered and the solid was taken and added to 10wt% aqueous hcl and stirred for 2 hours, filtered, dried to constant weight and weighed, the data are shown in table 1.

Example 15

The difference from example 14 is that complex 1 used is replaced by complex 2 (1.05 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Example 16

The difference from example 14 is that complex 1 used is replaced by complex 3 (0.86 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Example 17

The difference from example 14 is that complex 1 used is replaced by complex 4 (0.94 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Example 18

The difference from example 14 is that complex 1 used is replaced by complex 5 (0.86 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Example 19

The difference from example 14 is that complex 1 used is replaced by complex 6 (0.89 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Example 20

The difference from example 14 is that complex 1 used is replaced by complex 7 (0.92 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Example 21

The difference from example 14 is that complex 1 used is replaced by complex 8 (0.97 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Example 22

The difference from example 19 is that the ethylene oligomerization was carried out at 40℃and the data are shown in Table 1.

Example 23

The difference from example 19 is that the ethylene oligomerization was carried out at 80℃and the data are shown in Table 1.

Example 24

The difference from example 19 is that MMAO-3A is used in an amount of 0.32mmol and the data are shown in Table 1.

Example 25

The difference from example 19 is that MMAO-3A is used in an amount of 0.48mmol and the data are shown in Table 1.

Example 26

The difference from example 19 is that the reaction pressure for ethylene oligomerization was 400psig and the data are shown in Table 1.

Example 27

The difference from example 19 is that the reaction pressure for ethylene oligomerization was 300psig and the data are shown in Table 1.

Comparative example 1

The difference from example 14 is that complex 1 used is replaced by complex 9 (1.02 mg, 0.8. Mu. Mol) and the data are given in Table 1.

Comparative example 2

The difference from example 14 is that complex 1 used is replaced by complex 10 (0.54 mg, 0.8. Mu. Mol) and MMAO-3A is used in an amount of 0.4mmol, the data being given in Table 1.

Comparative example 3

The difference from example 14 is that complex 1 used is replaced by complex 10 (0.54 mg, 0.8. Mu. Mol) and MMAO-3A is used in an amount of 0.2mmol, the data being given in Table 1.

Comparative example 4

The difference from example 14 is that complex 1 used is replaced by complex 11 (0.46 mg, 0.8. Mu. Mol) and MMAO-3A is used in an amount of 0.2mmol, the data being given in Table 1.

Comparative example 5

The difference from example 14 is that complex 1 used is replaced by complex 12 (0.50 mg, 0.8. Mu. Mol) and MMAO-3A is used in an amount of 0.2mmol, the data being given in Table 1.

Comparative example 6

The difference from example 14 is that complex 1 used is replaced by complex 13 (0.48 mg, 0.8. Mu. Mol) and MMAO-3A is used in an amount of 0.2mmol, the data being given in Table 1.

TABLE 1

As can be seen from Table 1, the catalyst provided by the invention has higher catalytic activity and selectivity, wherein the ligand L ⁶ has better catalytic performance, the activity can reach 4370kg/g Cr/h, the 1-octene selectivity reaches 74.8%, and the total selectivity of 1-hexene and 1-octene reaches 95.8%. As can be seen from comparative examples 1 and 3, 15 and 4, 16 and 5, 18 and 6, the phenyl bridged tetraphosphine ligand activity provided by the present invention is significantly improved over the phenyl bridged biphosphine ligand activity, and the solid polymer content is reduced; as can be seen by comparing comparative examples 1,2 and 3, the ligand provided by the present invention requires a reduced amount of cocatalyst, and higher activity can be achieved at lower amounts of cocatalyst.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the invention in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A catalyst for ethylene selective tetramerization containing tetraphosphine ligand, which is characterized by comprising ligand, transition metal compound and activator, wherein the chemical structural formula of the ligand is shown as the following formula (I):

In the method, in the process of the invention,

The groups R ₃ to R ₁₀ are each independently selected from alkyl, cycloalkyl, alkenyl or aromatic groups.

2. The catalyst for the selective tetramerization of ethylene containing tetraphosphine ligand according to claim 1, wherein the alkyl group is C ₁-C₃₀ alkyl group, specifically including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, cyclopentyl, n-hexyl, sec-hexyl, isohexyl, cyclohexyl, n-heptyl, cycloheptyl, n-octyl, n-decyl, 2-methylcyclopentyl or 2, 6-dimethylcyclohexyl.

3. A catalyst for the selective tetramerisation of ethylene containing tetraphosphine ligands according to claim 1, wherein said alkenyl is C ₁-C₃₀ alkenyl, specifically comprising vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-2-butenyl, 2-methyl-1-butenyl, 3-methyl-2-butenyl, 5-hexenyl, 2-cyclohexenyl, 3-cyclohexenyl or 2-methyl-2-cyclohexenyl; the halogen is fluorine, chlorine, bromine or iodine.

4. A catalyst for the selective tetramerization of ethylene containing tetraphosphine ligand according to claim 1, wherein the aromatic group is C ₄-C₃₀ aryl and its derivatives, specifically included are phenyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, 2, 6-difluorophenyl, 2, 5-difluorophenyl, 2, 4-difluorophenyl, 2, 3-difluorophenyl, 3, 4-difluorophenyl, 3, 5-difluorophenyl, 2, 6-dichlorophenyl, 2, 5-dichlorophenyl, 2, 4-dichlorophenyl, 2, 3-dichlorophenyl, 3, 4-dichlorophenyl, 3, 5-dichlorophenyl, p-ethylphenyl, o-ethylphenyl, m-ethylphenyl, 2, 4-dimethylphenyl, 2, 4-diisopropylphenyl, 2, 4-di-tert-butylphenyl, 2, 6-dimethylphenyl, 2, 6-diisopropylphenyl, 3, 5-dimethylphenyl, 3, 5-di-tert-butylphenyl, 2,4, 6-trimethylphenyl, naphthyl, anthracenyl, biphenyl, 7-fluoro-1-naphthyl, 8-fluoro-1-naphthyl, 7-chloro-1-naphthyl, 8-chloro-1-anthracenyl, and 1-anthracenyl.

5. A catalyst for the selective tetramerisation of ethylene containing a tetraphosphine ligand according to any of claims 1-4, wherein at least one of the groups R ₃ to R ₁₀ is not phenyl.

6. A catalyst for the selective tetramerisation of ethylene containing tetraphosphine ligands according to claim 1, characterized in that the transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, nickel or palladium; the activator comprises an alkyl aluminum compound, an aluminoxane compound or an organoboron compound; the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100): 1; the mole ratio of the activator to the transition metal element in the transition metal compound is (1-10000): 1.

7. The catalyst for the selective tetramerization of ethylene containing tetraphosphine ligand according to claim 6, wherein said aluminoxane compound specifically comprises modified methylaluminoxane MMAO-3A; the mole ratio of the activator to the transition metal element in the transition metal compound is (250-500): 1.

8. A process for the preparation of a catalyst for the selective tetramerisation of ethylene containing a tetraphosphine ligand according to any one of claims 1 to 7, characterised in that it comprises: the ligand, the transition metal compound and the activator are pre-mixed or directly added into a reaction system for in-situ synthesis, thus obtaining the ethylene selective tetramerization catalyst containing tetraphosphine ligand.

9. Use of a catalyst for the selective tetramerisation of ethylene containing a tetraphosphine ligand according to any of claims 1-7, wherein the catalyst is used for the selective tetramerisation of ethylene to 1-octene in an inert solvent at a temperature of 0-200 ℃, at a pressure of 10-5000psig and a concentration of transition metal in the transition metal compound in the inert solvent of 0.01-10000 μmol/L;

the inert solvent comprises one or more of alkane, arene, alkene or ionic liquid.

10. The use of a catalyst for the selective tetramerisation of ethylene containing tetraphosphine ligands according to claim 9, characterized in that the temperature of the reaction is 40-80 ℃; the pressure is 300-500psig.