WO2019113748A1

WO2019113748A1 - Catalyst system for selective oligomerization of ethylene and ethylene oligomerization reaction method

Info

Publication number: WO2019113748A1
Application number: PCT/CN2017/115490
Authority: WO
Inventors: 姜涛; 张乐; 陈延辉; 阿兰⋅法赫; 邵怀启; 李健; 闫冰
Original assignee: 天津科技大学
Priority date: 2017-12-11
Filing date: 2017-12-11
Publication date: 2019-06-20

Abstract

Provided is a catalyst system for the selective oligomerization of ethylene, the catalyst system belonging to the field of catalysis technologies. The catalyst system comprises three components: a ligand a; a transition metal compound b, which is a compound of a metal from Groups IVB-VIII; and an activator c, which is a compound containing a Group IIIA metal, wherein the ligand a comprises at least one phosphine amine group as represented by general formula I, and bridging group A is a bridging group comprised of an alkyl group, an alkenyl group or an aryl group and a heteroatom in the backbone, with the heteroatom being one of silicon, tin, boron, phosphorus, nitrogen, oxygen or sulfur; and R1, R2, and R3 are respectively substituent groups on two phosphine amine groups, with R1, R2, and R3 being the same or different. The present invention has the beneficial effects of the catalyst system having a high activity, the selectivities for target products 1-hexene and 1-octene being high, the mass percentage content of C6-C8 linear α-olefins in the product being > 90%, and the catalyst being simple to synthesize, low in cost and long in life span.

Description

Catalyst system for selective oligomerization of ethylene and ethylene oligomerization reaction method

Technical field

The invention belongs to the technical field of catalysis, and relates to a catalyst system for selective oligomerization of ethylene and an ethylene oligomerization reaction method.

Background technique

Linear alpha-olefins are an important class of organic chemicals that are widely used in homopolymerization and copolymerization to produce polyethylene, surfactants, lubricants and oil additives. The light component (C ₄ -C ₈ ) can be copolymerized with ethylene as a comonomer to produce 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.

As the global economy continues to grow, 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 5.4% or more. The industrial production methods of 1-hexene and 1-octene mainly include paraffin cracking, ethylene oligomerization and extraction separation, and the ethylene oligomerization method is the main method for producing 1-hexene and 1-octene. For example, US 6,184,428 discloses a nickel catalyst which employs a boron compound as a cocatalyst to catalyze the oligomerization of ethylene to give a mixture of linear alpha olefins wherein the content of 1-hexene is 22% and the content of 1-octene is 19%. In the SHOP process (US3676523, US Pat. No. 3,635,937), the content of 1-hexene in the ethylene oligomerization product accounts for 21%, and the content of 1-octene accounts for 11%. In the Ethyl process of Gulf Oil's Chevron process (DE1443927) and ethyl company (BP/Amoco, US3906053), the content of 1-hexene and 1-octene is also low, generally 13-25%. In addition, 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, 1-hexene, 1- The content of octene is also less than 20%. In the existing process, the content of 1-hexene and 1-octene in the oligomerization product cannot be too high. If high-purity 1-hexene and 1-octene are to be obtained by multi-tower rectification separation, the process route is complicated and the equipment investment is huge.

In view of this, the central metal of the ethylene selective trimerization catalyst currently studied is mainly chromium and titanium, and the chromium catalyst is used for the trimerization of ethylene to prepare 1-hexene (US5550305, US5198563), which has been industrialized, and the main product 1 The content of hexene is generally greater than 90%, but the content of 1-octene is less than 3%. The central metal of the ethylene tetramerization catalyst is mainly chromium. The ethylene tetramerization three-way catalyst system is highly selective for the synthesis of 1-octene (WO2004/056478A1, US2006/0229480 and US2006/0173226), and the content of 1-octene in the desired product reaches 60%. In addition, the ligand structure in the catalyst system plays an important role in the selective oligomerization of ethylene, and the structure of the ligand directly affects the selectivity of the ethylene selective oligomerization catalyst system.

Therefore, the design of a highly selective ethylene oligomerization catalyst system for the production of 1-hexene and 1-octene, while obtaining high levels of 1-hexene and 1-octene, deserves the attention of the industry.

Summary of the invention

In view of this, the present invention aims to propose a catalyst system for selective oligomerization of ethylene to solve the technical problem that the total selectivity of 1-hexene and 1-octene in the ethylene oligomerization reaction is not high.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A catalyst system for the selective oligomerization of ethylene comprising three components:

Ligand a;

a transition metal compound b, the transition metal compound b being a metal compound of Groups IVB to VIII;

Activator c, the activator c is a compound containing a Group IIIA metal;

Wherein the ligand a contains at least one phosphonium group as shown in the formula I, and the formula I is as follows:

The bridging group A is a bridging group containing a hetero atom and an alkyl group, an alkenyl group or an aryl group as a main chain, wherein the hetero atom is one of silicon, tin, boron, phosphorus, nitrogen, oxygen or sulfur. ; R ¹ , R ² and R ³ are each a substituent group on two phosphonamine groups, and R ¹ , R ² and R ^{3 are the} same or different.

Further, the bridging group A is -(CH ₂ )n-Si R"R"'-(CH ₂ ) _m - or -(CH ₂ )n-BR'-(CH ₂ ) _m -, wherein 0 ≤ n ≤ 3, 0 ≤ m ≤ 3; R", R"' and R' are each independently selected from methyl, isopropyl, cyclohexyl, cyclopentyl, phenyl, naphthyl or 2,6-di Isopropyl phenyl.

Further, the substituent groups R ¹ , R ² , and R ³ are each independently selected from the group consisting of methyl, isopropyl, cyclopentyl, cyclohexyl, phenyl, o-methylphenyl, o-ethylphenyl, ortho Isopropylphenyl, 2,4-dimethylphenyl, 2,4-diethylphenyl, 2,4-diisopropylphenyl, 2,4-dibutylphenyl, 2,6 -diisopropylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-dibutylphenyl, 2,4,6-trimethylphenyl, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, naphthyl, anthracenyl, biphenyl; preferably methyl, isopropyl, cyclohexyl, phenyl, 2,6-diisopropylphenyl or naphthyl.

Further, the transition metal compound b contains one of chromium, molybdenum, tungsten, lead, cobalt, titanium, ruthenium, vanadium, zirconium, iron, nickel or palladium.

Further, the transition metal compound b is one of CrCl ₃ (THF) ₃ , CoCl ₃ , PbCl ₂ (COD), and Pb(Ac) ₂ .

Further, the activator c is one or a mixture of two or more of an alkyl aluminum compound, an alkyl aluminoxane compound, an organoboron compound, an organic salt, an inorganic acid or an inorganic salt, wherein the alkyl aluminum The oxyalkylene compound includes an alkyl aluminoxane compound which removes volatile components.

Further, the activator c is a mixture of an alkyl aluminum compound and an alkyl aluminoxane compound from which a volatile component is removed, wherein the alkyl aluminum compound is triethyl aluminum (TEAL), the alkyl group The aluminoxane compound is methylaluminoxane (DMAO) which removes volatile components; the molar ratio of TEAL to DMAO is from 0.01 to 100, preferably from 0.1 to 10.

Further, the molar ratio of the ligand a, the transition metal compound b, and the activator c is a: b: c = 1: 0.5 to 100: 0.1 to 5000.

The invention also provides a preparation method of a catalyst system, comprising the steps of pre-mixing the ligand a, the transition metal compound b, the activator c or directly into the reaction system for in-situ synthesis.

The present invention also provides an ethylene oligomerization reaction process comprising ethylene oligomerization carried out in the presence of the above catalyst system.

Further, the reaction is carried out in an inert solvent which is one or a mixture of two or more of an alkane, an aromatic hydrocarbon, an olefin or an ionic liquid.

Further, the temperature of the reaction is from 0 ° C to 200 ° C.

Further, the pressure of the reaction is from 0.1 MPa to 50 MPa.

Compared to the prior art, the catalyst system for ethylene selective oligomerization described in the present invention has the following advantages:

(1) The catalyst system has high catalytic activity, and the total selectivity of the target products 1-hexene and 1-octene is high, and the 1-butene and 1-C ₁₀ ⁺ mass percentages are low, wherein the product is C ₆ - C _The linear percentage of the linear alpha-olefin is >90%.

(2) The catalyst system is simple in synthesis, low in cost, and long in catalyst life.

Detailed ways

The invention will now be described in further detail in connection with specific embodiments.

Embodiments of the present invention provide a catalyst system for selective oligomerization of ethylene comprising three components:

Ligand a;

Activator c, the activator c is a compound containing a Group IIIA metal;

The bridging group A is a bridging group composed of an alkyl group, an alkenyl group or an aryl group and a hetero atom as a main chain, wherein the hetero atom is silicon, tin, boron, phosphorus, nitrogen, oxygen or sulfur. One; R ¹ , R ² , and R ³ are each a substituent group on two phosphonamine groups, and R ¹ , R ² , and R ^{3 are the} same or different.

Embodiments of the present invention provide a catalyst system for selective oligomerization of ethylene, comprising three components of a ligand a, a transition metal compound b, and an activator c. Wherein, the ligand a is a ligand containing at least one bisphosphine group as shown in Formula I; the transition metal compound b is a metal compound of Groups IVB to VIII, which is a central metal atom; and the activator c is a group IIIA. A metal compound that acts primarily for activation. Catalyst system Under the action of activator c, ligand a effectively regulates the electronic effect and steric hindrance effect of the ligand on the active center of the metal according to the length of the bridging group A and the abundant substituent groups on each hetero atom. Finally, the catalyst system of the examples of the present invention can be used for selective oligomerization of ethylene with excellent total selectivity of 1-hexene and 1-octene.

In the ligand of the catalyst system provided by the embodiment of the present invention, first, the phosphonamine coordinating group is different from other monohetero atomic coordinating groups, and adopts a similar η ² coordination mode with the metallocene compound (η ⁵ ). It has stronger coordination ability, which makes the catalyst have better chemical stability. Secondly, the hetero atom in the bridging group A has stronger electronegativity than the carbon atom, and can also enhance the coordination of the ligand with the metal center. The ability to enhance its chemical stability; again, the length of the bridging group and the different substituent groups on each hetero atom have different steric hindrance effects on the metal active center, thereby affecting the selectivity of the catalyst.

In the activator of the catalyst system provided by the embodiment of the present invention, when the catalytic system catalyzes the oligomerization of ethylene, an appropriate compound containing a Group IIIA metal is selected according to the difference in alkylation strength to achieve an optimum activation.

Among the transition metal compounds of the catalyst system provided by the examples of the present invention, the metal compounds selected from the group IVB to VIII.

The catalyst system provided by the embodiment of the invention has a ligand structure combined with a corresponding transition metal compound and an activator, which has an important influence on the catalytic activity of selective oligomerization of ethylene and the selectivity of 1-hexene and 1-octene, and the ligand structure The type and number of the mesogenic groups and the type and length of the bridging group exert an influence on the metal active center from both the electronic effect and the steric hindrance effect, thereby affecting the catalytic activity and selectivity of the catalyst, so that the present invention is implemented. The catalyst system provided by the example can achieve high selectivity of 1-hexene and 1-octene when ethylene oligomerizes.

In an embodiment of the invention, the molar ratio of the ligand a to the transition metal compound b in the catalyst system may be from 1:0.5 to 100.

In still another embodiment of the present invention, the molar ratio of the ligand a to the activator c in the catalyst system may be from 1:0.1 to 5,000, preferably from 1:1 to 1,000, more preferably from 1:1 to 200.

Specifically, the molar ratio of the ligand a, the transition metal compound b, and the activator c is 1:0.5 to 100:0.1 to 5000; preferably, the molar ratio of the ligand a, the transition metal compound b, and the activator c is 1. 0.5 to 100: 0.1 to 1000; more preferably, the molar ratio of the ligand a, the transition metal compound b, and the activator c is 1:0.5 to 100:0.1 to 200.

In an embodiment of the invention, the catalyst system further comprises an inert solvent, which may be an alkane, an aromatic hydrocarbon, an olefin or an ionic liquid, preferably methylcyclohexane.

The three components of the catalyst system of the present invention are further illustrated below.

(1) Ligand a

In an embodiment of the invention, the bridging group A contains a hetero atom, which is one of silicon, tin, boron, phosphorus, nitrogen, oxygen or sulfur. In still another embodiment of the present invention, the bridging group A includes a bridging group of a linear alkane as a main chain, and the linear alkane is methane, ethane, propane, butane, pentane or hexane.

In still another embodiment of the present invention, the bridging group A includes a bridging group of an aromatic hydrocarbon or an olefin group as a main chain, the olefin may be ethylene, propylene, butylene, and the aromatic hydrocarbon may be benzene or toluene.

In still another embodiment of the present invention, the bridging group A main chain contains a hetero atom and a bridging group of an alkyl group, an alkenyl group or an aryl group of 1 to 8 carbon atoms. This distance is more favorable for coordination between atoms.

Preferably, the bridging group A may be a linear bridging group containing a silicon atom or a boron atom -(CH ₂ )n-SiR"R"'-(CH ₂ ) _m - or -(CH ₂ )n- BR'-(CH ₂ ) _m -, wherein 0 ≤ n ≤ 3, 0 ≤ _m ≤ 3; R", R"' and R' are independently selected from methyl, isopropyl, cyclohexyl, cyclopentyl, Phenyl, naphthyl or 2,6-diisopropylphenyl.

Preferably, the bridging group A may be -(CH ₂ ) _n Sn(R ⁶ R ⁷ )(CH ₂ ) _m -, -(CH ₂ ) _n P(R ⁶ )(CH ₂ ) _m -, -(( CH ₂ ) _n N(R ⁶ )(CH ₂ ) _m -, -(CH ₂ ) _n O(CH ₂ ) _m - or -(CH ₂ ) _n S(CH ₂ ) _m -(0≤n≤4, 0≤m≤4), wherein R ⁶ and R ⁷ are each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, cyclopentyl, cyclohexyl, isobutyl, tert-butyl Base, adamantyl, vinyl, allyl, phenyl, benzyl, phenyl, tolyl, xylyl, 2,4,6-trimethylphenyl, 3,5-xylenemethyl, A Oxyphenyl, ethylphenyl, thiophenyl, bisphenyl, naphthyl or anthracenyl.

In still another embodiment of the present invention, the substituent groups R ¹ , R ² , and R ³ are each independently selected from the group consisting of methyl, isopropyl, cyclopentyl, cyclohexyl, phenyl, o-methylphenyl, o-ethyl. Phenyl, o-isopropylphenyl, 2,4-dimethylphenyl, 2,4-diethylphenyl, 2,4-diisopropylphenyl, 2,4-dibutylphenyl , 2,6-diisopropylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-dibutylphenyl, 2,4,6-trimethyl Phenyl, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, naphthyl, anthracenyl, biphenyl; preferably methyl, isopropyl, cyclohexyl , phenyl, 2,6-diisopropylphenyl or naphthyl.

In still another embodiment of the invention, the substituent R ^{3 is} selected from phenyl.

In still another embodiment of the present invention, the substituent R ^{3 is} independently selected from isopropyl, cyclopentyl, methyl or cyclohexyl.

In one embodiment of the present invention, the ligand a may be one or two or more units of the structure of the formula I, which are bonded together by groups, chemical bonds or intermolecular forces to obtain bridges, dendrites and stars. The compound may also be a polymerized polymer formed by binding to a polymer chain.

In one embodiment of the invention, the ligand a may be (R ² ) ₂ PNR ³ ANR ³ P(R ¹ ) ₂ , wherein A is a bridging group containing the above hetero atom; R ¹ , R ² , R ³ Respectively a substituent group on two phosphonamine groups, R ¹ , R ² , R ^{3 are the} same or different and are independently selected from methyl, isopropyl, cyclohexyl, cyclopentyl, phenyl, 2, 6 - Diisopropylphenyl or naphthyl.

In an embodiment of the present invention, the ligand a may also be -[(R ² ) ₂ PNR ³ ANR ³ P(R ¹ ) ₂ ] _n B, n≥2, wherein A is a bridging group containing the above hetero atom. R ¹ , R ² , and R ³ are each a substituent group on two phosphonamine groups, and R ¹ , R ² , and R ^{3 are the} same or different and are independently selected from methyl, isopropyl, cyclohexyl, Phenyl, 2,6-diisopropylphenyl or naphthyl; B is a bridging group between formula I, which may be methyl, hexyl, propyl or butyl, or may be aryl and A bridging group containing a hetero atom.

(2) Transition metal compound b

In an embodiment of the invention, the transition metal compound b contains one of chromium, molybdenum, tungsten, lead, cobalt, titanium, ruthenium, vanadium, zirconium, iron, nickel or palladium.

Preferably, the transition metal compound b is one of CrCl ₃ (THF) ₃ , CoCl ₃ , PbCl ₂ (COD), and Pb(Ac) ₂ .

Preferably, the transition metal compound b is a transition metal compound containing chromium, zirconium or titanium.

More preferably, the transition metal compound b is a chromium-containing transition metal compound. The optional chromium compound includes a compound of the formula CrR ⁿ _m wherein R ⁿ is an organic negative ion or a neutral molecule, R ⁿ usually contains 1 to 10 carbon atoms, n is an integer of 0 to 6, and chromium The price is 0 to 6. Specific R ⁿ groups are organic groups containing a carboxyl group, a β-diketone group, and a hydrocarbon group or a group thereof. From the viewpoints of ease of dissolution and ease of handling, more suitable chromium compounds include chromium acetate, chromium isooctanoate, chromium n-octanoate, chromium acetylacetonate, chromium diisoprene, diphenylchromium, CrCl ₃ (THF) ₃ , CrCl. ₂ (THF) ₂ , (phenyl) tricarbonyl chromium, hexacarbonyl chromium.

(3) Activator c

In an embodiment of the invention, the activator c is an alkyl aluminum compound, an alkyl aluminoxane compound, or an organic boron. One or a mixture of two or more of a compound, an organic salt, an inorganic acid or an inorganic salt, wherein the alkyl aluminoxane compound includes an alkyl aluminoxane which removes a volatile component.

Specifically, the aluminum alkyl compound may be various trialkyl aluminums such as TEAL, triisobutyl aluminum, tri-n-butyl aluminum, tri-n-hexyl aluminum or tri-n-octyl aluminum; alkyl aluminum compounds may also be used. Is an alkyl aluminum halide, an alkyl aluminum hydride or an alkyl aluminum sesquichloride such as AlEt ₂ Cl and A1 ₂ Et ₃ C1 ₃ ; the alkyl aluminoxane compound may be selected from methyl aluminoxane (MAO) , ethyl aluminoxane, isobutyl aluminoxane, modified aluminoxane, and methyl aluminoxane to remove volatile components.

Specifically, the activator c is a mixture of an alkyl aluminum compound and an alkyl aluminoxane which removes a volatile component, wherein the alkyl aluminum compound is TEAL, and the alkyl aluminoxane compound is DMAO .

Preferably, the molar ratio of TEAL to DMAO is from 0.01 to 100, preferably from 0.1 to 10.

In still another embodiment of the present invention, an organic salt activator such as methyl lithium, methyl magnesium bromide or the like; an inorganic acid and an inorganic salt activator such as tetrafluoroborate etherate, tetrafluoroborate, hexafluorocarbon A phthalate or the like; the organoboron compound includes boroxine, sodium borohydride, triethylborane, tris(pentafluorophenyl)boron, tributylborate, and the like.

According to the above, in an embodiment of the present invention, in a suitable catalyst system, the bridging group A in the ligand a may be -(CH ₂ )n-SiR"R"'-(CH ₂ ) _m - or -(CH ₂ )n-BR'-(CH ₂ ) _m -, wherein 0 ≤ n ≤ 3, 0 ≤ _m ≤ 3; R", R"' and R' are independently selected from methyl, isopropyl, Cyclohexyl, cyclopentyl, phenyl, naphthyl or 2,6-diisopropylphenyl, the bridging group A of the ligand a may also be -(CH ₂ ) _n Sn(R ⁶ R ⁷ )( CH ₂ ) _m -, -(CH ₂ ) _n P(R ⁶ )(CH ₂ ) _m -, -(CH ₂ ) _n N(R ⁶ )(CH ₂ ) _m -, -(CH ₂ ) _n O( CH ₂ ) _m - or -(CH ₂ ) _n S(CH ₂ ) _m - (0 ≤ _{n ≤} ₄ , _{0 ≤} _m ≤ 4), wherein R ⁶ and R ⁷ may be independently selected from methyl and ethyl , n-propyl, isopropyl, n-butyl, cyclopentyl, cyclohexyl, isobutyl, tert-butyl, adamantyl, vinyl, allyl, phenyl, benzyl, phenyl, toluene Base, xylyl, 2,4,6-trimethylphenyl, 3,5-xylenemethyl, methoxyphenyl, ethylphenyl, thiophenyl, bisphenyl, naphthyl or anthracenyl. The substituent groups R ¹ , R ² and R ^{3 of the} ligand a are each independently selected from methyl, isopropyl, cyclohexyl, phenyl, 2,6-diisopropylphenyl or naphthyl;

The transition metal compound b may be one of CrCl ₃ (THF) ₃ , CoCl ₃ , PbCl ₂ (COD), and Pb(Ac) ₂ ; or may be chromium acetate, chromium isooctanoate, chromium n-octanoate, chromium acetylacetonate, One of diisoprene chromium, diphenylchromium, CrCl ₃ (THF) ₃ , CrCl ₂ (THF) ₂ , (phenyl) chromium tricarbonyl, chromium hexacarbonyl;

The activator c may be a trialkyl aluminum such as TEAL, triisobutyl aluminum, tri-n-butyl aluminum, tri-n-hexyl aluminum or tri-n-octyl aluminum; or may be an alkyl aluminum halide or an alkyl aluminum hydrogenated Or an alkyl aluminum sesquichloride such as AlEt ₂ Cl and A1 ₂ Et ₃ C1 ₃ ; the aluminoxane compound may be selected from the group consisting of methyl aluminoxane, ethyl aluminoxane, isobutyl aluminoxane and modification Aluminoxane and methylaluminoxane to remove volatile components. The activator c may also be a mixture of one or more of the above, such as the activator c being a mixture of the TEAL and the DMAO, wherein the molar ratio of the TEAL to the DMAO is 0.01 to 100, preferably 0.1 to 10. The activator c may also be an organic salt activator such as methyl lithium, methyl magnesium bromide or the like or an inorganic acid and an inorganic salt activator such as tetrafluoroborate etherate, tetrafluoroborate, hexafluoroantimony. The acid salt or the like; or the organic boron compound includes boroxine, sodium borohydride, triethylborane, tris(pentafluorophenyl)boron, tributylborate or the like.

The preparation method of the catalyst system of the present invention will be further described below.

In an embodiment of the invention, the synthesis of the ligand a comprises the following steps:

(1) Preparation of R ³ NHLi. A certain amount of R ³ NH _{2 is first} dissolved in an appropriate amount of n-hexane, and then n-butyllithium is added dropwise at a certain temperature to form R ³ NHLi.

(2) Preparation of R ³ NHPR ¹ ₂ . Appropriate amount of R ³ NHLi was dispersed in n-hexane; an appropriate amount of R ¹ ₂ PCl solution in n-hexane was added, and it was slowly added dropwise to the hexane turbid solution of R ³ NHLi, stirred at room temperature overnight, and then filtered through a sand core funnel. After concentration in vacuo, crystallization treatment was carried out to obtain R ³ NHPR ¹ ₂ .

(3) Preparation of R ³ NLiPR ¹ ₂ . A certain amount of R ³ NHPR ¹ _{2 was} dissolved in n-hexane, cooled to -35 ° C, and a certain amount of n-butyl lithium n-hexane solution was slowly added dropwise to the above solution, and then naturally increased to room temperature after the completion of the addition, and continued. After stirring for 2 h and then filtering through a sand core funnel, the filter cake was the R ³ NLiPR ¹ ₂ product.

(4) Dissolve a certain amount of R ³ NLiPR ¹ ₂ in toluene, slowly add a certain concentration of the dichloride toluene solution of A to the above solution, stir at room temperature overnight, then filter with a sand core funnel and concentrate in vacuo. Further, crystallization treatment is carried out to obtain a white or pale yellow solid which is the ligand a.

In an embodiment of the invention, the method for preparing the catalyst system comprises the following steps:

The components a, b, c are premixed or added directly to the reaction system for in situ synthesis. That is to say, the preparation of the catalyst is to premix the ligand a, the transition metal compound b, and the activator c which are connected by a bridging group containing a hetero atom; or to be linked by a chain group containing a hetero atom; The body a, the transition metal compound b, and the activator c are directly added to the reaction system for in situ synthesis;

The reaction mode of the ligand a, the transition metal compound b and the activator c which are linked by the hetero atom-containing bridging group described in the general formula I can be carried out by a liquid phase reaction, for example, under the action of a solvent. The selected solvent such as toluene, benzene and its derivatives may also be reacted by a solid phase; or may be formed by in situ reaction during the oligomerization reaction. The reaction described herein may be a reaction between one, two, and three compounds of the above hetero atom ligand, transition metal compound, and metal organic activator. The process of this reaction is also the aging (pre-complexation) process of the catalyst.

The method for the oligomerization of ethylene in the catalyst system of the present invention is further illustrated below.

The present invention also provides an ethylene oligomerization reaction process comprising the ethylene oligomerization reaction carried out in the presence of the above catalyst system.

In an embodiment of the invention, the reaction is carried out in an inert solvent which is one or more of an alkane, an aromatic hydrocarbon, an olefin or an ionic liquid. 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. Methylcyclohexane is preferred.

In still another embodiment of the present invention, the reaction temperature is from 0 ° C to 200 ° C, preferably from 50 ° C to 150 ° C.

In still another embodiment of the present invention, the pressure of the ethylene oligomerization reaction may be carried out at a pressure of from 0.1 MPa to 50 MPa, preferably from 1.0 MPa to 10 MPa.

In still another embodiment of the present invention, the concentration of the catalyst in the reaction system may be from 0.01 μmol of metal/L to 1000 μmol of metal/L, preferably 0.1 μmol of metal/L to 10 μmol of metal/L.

The content of the present invention will be further clarified below with reference to specific examples, but the content of the present invention is not limited to the following embodiments.

Example 1

1. Preparation of ligand: N,N'-bis(diisopropylphosphino)-1,1-dimethyl-N,N'-diphenylsilanediamine (C ₂₆ H ₄₄ N ₂ P ₂ Si)

(1) Preparation of anilinolithium

Dehydrated THF (200 ml) and lithium anilide (9.31 g, 0.1 mol) were added to a stirred 500 ml reactor which was sufficiently substituted with N ₂ , stirred well and then cooled to -78 ° C with liquid nitrogen. A n-butyl lithium hexane solution (41.6 ml, 2.4 mol/L) was extracted with a 100 ml syringe, and slowly added dropwise to the above solution while stirring, and the mixture was stirred at -78 ° C for 1 hour, then allowed to warm to room temperature, and further stirred for 1 hour, and then vacuumed. In addition to the solvent, n-hexane (100 ml) was added, and the mixture was thoroughly stirred and filtered, and the obtained filtrate was evaporated to dryness.

(2) Preparation of 1,1-diisopropyl-N-phenylphosphinoamine (C ₁₂ H ₂₀ NP)

Lithium anilide (4.95 g, 0.050 mol) was dissolved in dehydrated n-hexane (100 ml) in a N ₂ atmosphere glove box and added to a 250 mL reactor, cooled to -35 ° C, vigorously stirred; Isopropylphosphonium chloride (7.48g, 0.049mol) was slowly added dropwise to the above solution. After completion, it was naturally warmed to room temperature and stirring was continued overnight. After filtration, the volatile components in the filtrate were vacuumed to obtain a yellow liquid. Distillation was carried out, and a fraction of 145 ° C to 150 ° C was collected to obtain a colorless liquid product of 8.79 g (0.042 mol, 85%).

(3) Preparation of N,N'-bis(diisopropylphosphino)-1,1-dimethyl-N,N'-diphenylsilanediamine (C ₁₂ H ₂₀ NPLi)

In a glove box of N ₂ atmosphere, 1,1-diisopropyl-N-phenylphosphinoamine (8.37 g, 0.040 mol) was dissolved in dehydrated n-hexane (100 mL) and cooled to -35 ° C. The n-butyllithium n-hexane solution (17.1 mL, 0.041 mol, 2.4 mol/L) was slowly added dropwise to the above solution while stirring. After the completion of the dropwise addition, stirring was continued overnight, and the filter cake was washed twice with 20 mL of n-hexane after filtration. , draining to obtain 1.39 g (0.039 mol, 98%) of 1,1-diisopropyl-N-phenylphosphinoamine lithium, and dispersing the obtained intermediate product in n-hexane (100 mL), and cooling to -35 ° C, Dimethyldichlorosilane (2.45 g, 0.019 mol) was dissolved in 20 mL of n-hexane, slowly added dropwise to the above solution, naturally warmed to room temperature, stirred overnight, the volatile component was removed in vacuo, and the residue was extracted with 50 mL of toluene. After filtration, the volatile component was evaporated in vacuo, washed twice with 20 mL of hexanes and dried to yield 13.77 g of product (0.029 mol, 73%).

The products obtained from the experiments were verified to be structurally correct by nuclear magnetic resonance spectroscopy.

2. Preparation of catalyst

Was added in 100mL of dehydrated reactor was thoroughly purged with N ₂ was stirred in methylcyclohexane (20mL) DMAO (0.57g, 9.9mmol ), TEAL (0.38g, 3.3mmol), N, N'- Bis(diisopropylphosphino)-1,1-dimethyl-N,N'-diphenylsilanediamine (32 mg) (67.8 μmol), CrCl ₃ · (THF) ₃ (12 mg, 33 μmol), After reacting for 5 min at room temperature, it was used.

3. Ethylene oligomerization

The 500 mL autoclave was heated to evacuation for 2 hours, replaced with nitrogen several times, charged with ethylene, cooled to a predetermined temperature, and dehydrated methylcyclohexane (200 mL) and the above catalyst were added. The oligomerization reaction was carried out at 45 ° C under a pressure of 1 MPa, and after reacting for 30 minutes, the mixture was cooled with an ice bath, pressure was released, and the reaction was terminated with an acidified ethanol having a mass fraction of 10%. The oligomerized product was 35.5 g and the catalyst activity was 2.15 x 10 ⁶ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 2

Same as Example 1. The difference is that R ¹ and R ² are each a phenyl group, and R ³ is a cyclopentyl group. The oligomerized product was obtained in an amount of 83.2 g, and the catalyst activity was 5.04 × 10 ⁶ g of oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 3

Same as Example 1. The difference is that R ¹ , R ² and R ³ are all isopropyl groups, and A is a dimethylsilyl group (-Si(CH ₃ ) ₂ CH ₂ -). 91.7 g of an oligomerization product was obtained, and the catalyst activity was 5.56 × 10 ⁶ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 4

Same as Embodiment 2. The difference is that A is a dimethyldimethylenesilyl group (-CH ₂ Si(CH ₃ ) ₂ CH ₂ -). The oligomerized product 77.1 g was obtained, and the catalyst activity was 4.67 × 10 ⁶ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 5

Same as Embodiment 2. The difference is that A is a methylcyclohexyldimethylenesilyl group (-CH ₂ Si(CH ₃ )(C ₆ H ₁₁ )CH ₂ -). 65.7 g was obtained with a catalyst activity of 3.98 x 10 ⁶ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 6

Same as Embodiment 2. The difference is that A is a methylphenyl dimethylene silicon group (-CH ₂ Si(CH ₃ )(C ₆ H ₅ )CH ₂ -). 82.9 g was obtained with a catalyst activity of 5.02 x 10 ⁶ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 7

Same as Embodiment 2. The difference is that A is a diphenyl dimethylene silicon group (-CH ₂ Si(C ₆ H ₅ ) ₂ CH ₂ -). 85.2 g was obtained and the catalyst activity was 5.16 x 10 ⁶ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 8

Same as Embodiment 2. The difference is that R ³ is an isopropyl group and A is a phenyl boron group (-B(C ₆ H ₅ )-). The oligomerized product was obtained in an amount of 62.5 g, and the catalyst activity was 3.79 × 10 ⁶ g of oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 9

Same as Embodiment 4. The difference is that the ethylene pressure is 2 MPa. The oligomerized product was obtained in an amount of 112.5 g, and the catalyst activity was 6.82 × 10 ⁶ g of oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 10

Same as Embodiment 4. The difference was that the ethylene pressure was 4 MPa, the oligomerized product was 226.1 g, and the catalyst activity was 1.37 × 10 ⁷ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 11

Same as Embodiment 4. The difference was that the reaction temperature was 0 ° C, and an oligomerization product of 23.3 g was obtained, and the catalyst activity was 1.41 × 10 ⁶ g of oligomer/mol Cr·.h. The distribution of oligomerized products is shown in Table 1.

Example 12

Same as Embodiment 4. The difference was that the reaction temperature was 75 °C. The oligomerized product 66.2 g was obtained, and the catalyst activity was 4.01 × 10 ⁶ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 13

Same as Embodiment 4. The difference was that the amount of CrCl ₃ ·(THF) ₃ was 3 μmol. The oligomerized product was obtained in an amount of 34.7 g, and the catalyst activity was 1.01 × 10 ⁷ g of oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 14

Same as Embodiment 10. The difference is that the cocatalyst is MAO. The oligomerized product was obtained in an amount of 302.0 g, and the catalyst activity was 1.83 × 10 ⁷ g oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

Example 15

Same as Embodiment 10. The difference is that the cocatalyst is MMAO. The oligomerized product 125.1 g was obtained, and the catalyst activity was 7.58 × 10 ⁶ g oligomer / mol Cr.·h. The distribution of oligomerized products is shown in Table 1.

Example 16

Same as Example 11. The difference is that the chromium compound is CrCl ₂ (THF) ₂ . The oligomerized product was obtained in an amount of 22.8 g, and the catalyst activity was 1.38 × 10 ⁶ g of oligomer/mol Cr·h. The distribution of oligomerized products is shown in Table 1.

The experimental conditions and catalyst activities of Examples 1 to 16 are shown in Table 2.

It can be obtained from experimental data that the catalyst system can catalyze the highly selective trimerization and tetramerization of ethylene to hexene and octene, wherein 1-hexene and 1-octene have higher total selectivity. Further, in the case where R ³ is a phenyl group in Example 1, the steric hindrance is relatively large, the catalytic system catalyzes the highly selective trimerization of ethylene, and the 1-C ₆ selectivity is relatively high; in Examples 3 to 16, R ³ is different. When propyl and cyclopentyl are used, the steric hindrance is relatively small, and the catalytic system catalyzes the highly selective tetramerization of ethylene.

Further, in Example 14, when the cocatalyst was MAO, the product became an S-F distribution, indicating that when the cocatalyst was mixed with DMAO and TEAL, the catalytic system catalyzed the best selectivity for ethylene trimerization and tetramerization. Because the TEAL alkylation ability is relatively weak, it is more suitable for the catalyst system proposed by the present invention; at the same time, DMAO can shield the influence of volatile components such as toluene on the complexation process of the catalyst, thereby improving the activity of the catalyst system.

Table 1 Comparison of carbon number distribution of oligomerized products

It refers to ^a 1-C ₆ ⁼ C ₆ content percentage. ^b means 1-C ₈ ⁼ percentage content of C _8.

Table 2 Experimental conditions and catalyst activity of Examples 1 to 16

Claims

A catalyst system for the selective oligomerization of ethylene, characterized in that it comprises three components:

Ligand a;

a transition metal compound b, the transition metal compound b being a metal compound of Groups IVB to VIII;

Activator c, the activator c is a compound containing a Group IIIA metal;

Wherein the ligand a contains at least one phosphonium group as shown in the formula I, and the formula I is as follows:

The bridging group A is a bridging group containing a hetero atom and an alkyl group, an alkenyl group or an aryl group as a main chain, wherein the hetero atom is one of silicon, tin, boron, phosphorus, nitrogen, oxygen or sulfur. ; R 1 , R 2 and R 3 are each a substituent group on two phosphonamine groups, and R 1 , R 2 and R 3 are the same or different.
The catalyst system according to claim 1 wherein said bridging group A is -(CH 2 )n-SiR"R""-(CH 2 ) m - or -(CH 2 )n-BR '-(CH 2 ) m -, where 0 ≤ n ≤ 3, 0 ≤ m ≤ 3; R", R'" and R' are independently selected from methyl, isopropyl, cyclohexyl, cyclopentyl, benzene Base, naphthyl or 2,6-diisopropylphenyl.
The catalyst system according to claim 1 or 2, wherein the substituent groups R 1 , R 2 and R 3 are each independently selected from the group consisting of methyl, isopropyl, cyclopentyl, cyclohexyl and phenyl. , o-methylphenyl, o-ethylphenyl, o-isopropylphenyl, 2,4-dimethylphenyl, 2,4-diethylphenyl, 2,4-diisopropylphenyl 2,4-Dibutylphenyl, 2,6-diisopropylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-dibutylbenzene Base, 2,4,6-trimethylphenyl, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, naphthyl, anthracenyl, biphenyl; preferred Methyl, isopropyl, cyclopentyl, cyclohexyl, phenyl, 2,6-diisopropylphenyl or naphthyl.
The catalyst system according to claim 1, wherein said transition metal compound b contains one of chromium, molybdenum, tungsten, lead, cobalt, titanium, ruthenium, vanadium, zirconium, iron, nickel or palladium.
The catalyst system according to claim 1, wherein said activator c is one or more of an alkyl aluminum compound, an alkyl aluminoxane compound, an organoboron compound, an organic salt, an inorganic acid or an inorganic salt. a mixture; wherein the alkyl aluminoxane compound comprises an alkyl aluminoxane compound that removes volatile components.
a catalyst system according to claim 1 or 5,

The activator c is a mixture of an alkyl aluminum compound and an alkyl aluminoxane compound which removes a volatile component, wherein the alkyl aluminum compound is triethyl aluminum, and the aluminoxane compound To remove the volatile component of methylaluminoxane; the molar ratio of the triethylaluminum to the methylaluminoxane from which the volatile component is removed is from 0.01 to 100, preferably from 0.1 to 10.
The catalyst system according to claim 1, wherein the molar ratio of the ligand a, the transition metal compound b, and the activator c is from 1:0.5 to 100:0.1 to 5,000.
An ethylene oligomerization reaction process comprising the ethylene oligomerization reaction carried out in the presence of the catalyst system according to any one of claims 1-7.
The ethylene oligomerization reaction process according to claim 8, wherein the reaction is carried out in an inert solvent which is one or a mixture of two or more of an alkane, an aromatic hydrocarbon, an olefin or an ionic liquid.
The ethylene oligomerization reaction method according to claim 8, wherein the reaction temperature is from 0 ° C to 200 ° C; and the reaction pressure is from 0.1 MPa to 50 MPa.