Preparation method of straight-chain alpha-olefin

Abstract

The invention provides a preparation method of straight-chain alpha-olefin, which comprises the following steps: step 1, mixing straight-chain internal olefin with an alkyl aluminum compound, and carrying out isomerization reaction and alkyl replacement reaction under the action of a transition metal catalyst to obtain a replaced alkyl aluminum compound; step 2, mixing a substituted alkyl aluminum compound with a first straight-chain alpha-olefin, and carrying out an alkyl replacement reaction under the action of the transition metal catalyst to obtain the straight-chain alpha-olefin, the structural formula of the transition metal catalyst is (CH3) 2 [CH3 (CH2) n] C-O-Ni * xMX, m is alkali metal, X is halogen, the value range of x is 0.5-2, and n is 0, 1 or 2. The catalyst disclosed by the invention has relatively high catalytic efficiency, and when the catalyst is used for catalytically preparing the high-carbon-number straight-chain alpha-olefin, the yield of the target product high-carbon-number straight-chain alpha-olefin is relatively high.

Description

Technical Field

[0001] The present invention relates to the field of olefin preparation, and in particular to a method for preparing linear alpha-olefin. Background Art

[0002] Higher α-olefins play an important role as comonomers of polyolefins and as organic intermediates.

[0003] As for the preparation method of advanced α-olefins and the catalyst used therefor, CN1980873A discloses a method for preparing linear α-olefins from raw materials other than ethylene in a targeted manner, comprising the following steps: (a) dimerizing a linear α-olefin having n carbon atoms in the presence of a dimerization catalyst to produce a linear internal olefin having 2n carbon atoms; (b)(i) reacting the linear internal olefin having 2n carbon atoms produced in step (a) with a trialkylaluminum compound in the presence of a catalytic amount of an isomerization / displacement catalyst that simultaneously catalyzes isomerization and displacement, so as to isomerize the linear internal olefin and displace the alkyl group of the trialkylaluminum compound to form an alkylaluminum compound, wherein at least one alkyl group bonded to aluminum is a linear alkyl group derived from isomerizing the linear internal olefin, and (b)(ii) optionally reacting the alkylaluminum compound with an α-olefin in the presence of a displacement catalyst, so as to displace the linear alkyl group of the alkylaluminum compound to form a linear α-olefin having 2n carbon atoms, wherein n is an integer from 3 to 11. Wherein the isomerization / replacement catalyst is selected from nickel catalysts of nickel (II) salts and nickel (0) complexes and mixtures thereof, examples of nickel (II) carboxylates include nickel acetate, nickel 2-ethylhexanoate, nickel octoate and nickel cyclohexane acid, and examples of Ni (0) complex catalysts include Ni (CO) 4 and Ni (0) olefin complexes, such as bis-1,5-cyclooctadiene nickel (Ni (COD) 2), Ni (C2H4) 3, Ni (norbornene) 3 and cyclododecantriene. However, the yield of the target product needs to be further improved. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing linear α-olefins, so as to overcome the defects of low catalytic efficiency of catalysts used in the prior art for producing linear α-olefins, thereby resulting in low yield of target olefins.

[0005] In order to achieve the above object, the present invention provides a method for preparing linear α-olefins, comprising the following steps:

[0006] Step 1, mixing a linear internal olefin with an alkyl aluminum compound, and causing an isomerization reaction and an alkyl substitution reaction under the action of a transition metal catalyst to obtain a substitution alkyl aluminum compound;

[0007] Step 2, mixing the substituted alkyl aluminum compound with the first linear α-olefin, and causing an alkyl substitution reaction under the action of the transition metal catalyst to obtain the linear α-olefin;

[0008] Wherein, the structural formula of the transition metal catalyst is: (CH3)2[CH3(CH2) n ]CO-Ni*xMX; M is an alkali metal, X is a halogen, x is in the range of 0.5-2, and n is 0, 1 or 2.

[0009] In order to achieve the above object, the present invention also provides a method for preparing linear α-olefins, comprising the following steps:

[0010] Step 1, mixing a linear internal olefin with an alkyl aluminum compound, and causing an isomerization reaction and an alkyl substitution reaction under the action of a transition metal catalyst to obtain a substitution alkyl aluminum compound;

[0011] Step 2, mixing the substituted alkyl aluminum compound with the first linear α-olefin, and causing an alkyl substitution reaction under the action of the transition metal catalyst to obtain the linear α-olefin;

[0012] Wherein, the preparation method of the transition metal catalyst comprises the following steps:

[0013] Step a, allowing the nickel source to react with the organic amine ligand to obtain an amine complex nickel;

[0014] Step b, reacting the amine complex nickel with a tertiary alcohol alkali metal salt to obtain a transition metal catalyst.

[0015] In the method for preparing the linear α-olefin of the present invention, the carbon number of the first linear α-olefin is different from that of the first linear α-olefin.

[0016] In the method for preparing the linear α-olefin of the present invention, the carbon number of the linear α-olefin is greater than the carbon number of the first linear α-olefin.

[0017] The method for preparing straight-chain α-olefins of the present invention, wherein the straight-chain internal olefin has 5-20 carbon atoms; the alkyl aluminum compound is tri-n-alkyl aluminum, and the alkyl group in the tri-n-alkyl aluminum has 2-10 carbon atoms; and the molar ratio of the straight-chain internal olefin to the alkyl aluminum compound is 1:1-200:1.

[0018] The method for preparing straight-chain α-olefins of the present invention, wherein, in step 1, the content of the transition metal catalyst in the reaction system is 1-1000 ppm; in step 1, the temperature of the isomerization reaction and the alkyl substitution reaction is 20° C. to 200° C., and the time is 0.1-2 hours.

[0019] The method for preparing straight-chain α-olefins of the present invention, wherein the carbon number of the first straight-chain α-olefin is 2-20, and the carbon number of the straight-chain α-olefin is the same as the carbon number of the straight-chain internal olefin; in step 2, the content of the transition metal catalyst in the reaction system is 1-1000ppm; the temperature of the alkyl substitution reaction in step 2 is -10°C to 200°C, and the time is 30 seconds to 2 hours.

[0020] The method for preparing straight-chain α-olefins of the present invention, wherein the nickel source is a nickel (II) compound, and the organic amine ligand is an alkyl diamine compound or an alkyl diamine carboxylic acid, wherein the alkyl diamine compound has 2-12 carbon atoms, and the alkyl diamine carboxylic acid has 3-12 carbon atoms.

[0021] The method for preparing straight-chain alpha-olefins of the present invention comprises the following steps: the nickel source is at least one of anhydrous nickel chloride, anhydrous nickel bromide, anhydrous nickel fluoride and dimethoxyethane nickel dichloride; the organic amine ligand is at least one of ethylenediamine, propylenediamine, butylenediamine, ethylenediaminetetraacetic acid, tetramethylethylenediamine, tetramethylpropylenediamine and tetramethylbutylenediamine; the molar ratio of the nickel source to the organic amine ligand is 1:1 to 1:10; the nickel source and the organic amine ligand are reacted in an organic solvent, the organic solvent is at least one of N-methylpyrrolidone, dioxane, tetrahydrofuran, tert-butyl alcohol, dichloromethane, benzene, toluene, acetone, pentane, hexane, heptane, octane and decane, the reaction temperature is 1-100°C, and the reaction time is 1-10h.

[0022] The method for preparing straight-chain alpha-olefins of the present invention comprises the following steps: the tertiary alcohol alkali metal salt is at least one of potassium tert-butoxide, sodium tert-butoxide, lithium tert-butoxide, potassium tert-amyl alcoholate, sodium tert-amyl alcoholate and lithium tert-amyl alcoholate; the molar ratio of the amine complex nickel to the tertiary alcohol alkali metal salt is 1:1-1:10; the amine complex nickel and the tertiary alcohol alkali metal salt are reacted in an organic solvent, and the organic solvent is at least one of N-methylpyrrolidone, dioxane, tetrahydrofuran, tert-butanol, dichloromethane, benzene, toluene, acetone, pentane, hexane, heptane, octane and decane; the reaction temperature of the amine complex nickel and the tertiary alcohol alkali metal salt is 1-100°C, and the reaction time is 1-48h.

[0023] Beneficial effects of the present invention:

[0024] The transition metal catalyst of the present invention is used to catalyze the isomerization of internal olefins and the alkyl substitution reaction to generate a higher alkyl aluminum, and then the higher alkyl aluminum and the low-carbon linear α-olefin undergo an olefin substitution reaction to generate a high-carbon linear α-olefin. The catalyst of the present invention has a high catalytic efficiency. When it is used to catalyze the preparation of high-carbon linear α-olefins, the yield of the target product high-carbon linear α-olefin is high. In addition, the catalyst of the present invention has a simple synthesis process, low industrial cost, and the catalyst is simple and easy to remove during post-treatment and will not affect subsequent experiments. DETAILED DESCRIPTION

[0025] The technical scheme of the present invention is described in detail below. The following implementation modes are implemented on the premise of the technical scheme of the present invention, and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following implementation modes. The structures or experimental methods of specific conditions are not specified in the following implementation modes, and generally conventional conditions are followed.

[0026] The present invention provides a transition metal catalyst having the structural formula: (CH3)2[CH3(CH2) n ]CO-Ni*xMX; M is an alkali metal, X is a halogen, x is in the range of 0.5-2, and n is 0, 1 or 2.

[0027] The catalyst of the invention has high catalytic efficiency. When the catalyst is used for catalytic preparation of high carbon number straight chain alpha-olefins, the yield of the target product high carbon number straight chain alpha-olefins is high.

[0028] Wherein, M is an alkali metal, and in one embodiment, M is K, Na, Li, etc. X is a halogen, and in one embodiment, X is F, Cl, Br, etc. x is a coefficient of MX, and the value range is 0.5-2, for example, 1.0, 1.2, 1.5, 1.8, etc.

[0029] In the transition metal catalyst of the present invention, the carbon connected to oxygen is connected to two methyl groups and one CH3(CH2) n - group, when n is 0, the CH3(CH2) n - group is methyl, when n is 1, the CH3(CH2) n - group is ethyl, when n is 2, the CH3(CH2) n - group is a propyl group. In addition, MX is combined with tertiary alkoxide nickel in a crystalline state.

[0030] The present invention also provides a method for preparing the above transition metal catalyst, comprising the following steps:

[0031] Step 1, a nickel source is subjected to a complex reaction with an organic amine ligand to obtain an amine complex nickel;

[0032] Step 2, reacting the amine complex nickel with a tertiary alcohol alkali metal salt to obtain a transition metal catalyst.

[0033] The preparation process of the transition metal catalyst of the present invention is carried out under an inert atmosphere, and the inert atmosphere is not particularly limited in the present invention, such as argon, nitrogen, etc., preferably argon. In one embodiment, the preparation process of the transition metal catalyst of the present invention is carried out in a glove box filled with an inert gas.

[0034] In the present invention, the nickel source contains a halogen element. In one embodiment, the nickel source is a nickel (II) compound, which may be an organic nickel compound or an inorganic nickel compound. In another embodiment, the nickel source is at least one of anhydrous nickel chloride, anhydrous nickel bromide, anhydrous nickel fluoride, and dimethoxyethane nickel dichloride; preferably anhydrous nickel chloride, anhydrous nickel bromide, and anhydrous nickel fluoride.

[0035] In one embodiment, the organic amine ligand of the present invention is an alkyl diamine compound or an alkyl diamine carboxylic acid, wherein the number of carbon atoms of the alkyl diamine compound is 2-12, and the number of carbon atoms of the alkyl diamine carboxylic acid is 3-12. The alkyl group in the alkyl diamine compound and the alkyl diamine carboxylic acid is, for example, a straight chain alkyl group, a branched chain alkyl group, etc., which are not particularly limited in the present invention. In another embodiment, the organic amine ligand of the present invention is at least one of ethylenediamine, propylenediamine, butylene diamine, ethylenediaminetetraacetic acid, tetramethylethylenediamine, tetramethylpropylenediamine, and tetramethylbutylene diamine; preferably tetramethylbutylene diamine and tetramethylethylenediamine.

[0036] In one embodiment, the molar ratio of the nickel source to the organic amine ligand is 1:1 to 1:10, preferably 1:1 to 1:5, and most preferably 1:1 to 1:2; the nickel source and the organic amine ligand are reacted in an organic solvent, and the organic solvent is at least one of N-methylpyrrolidone, dioxane, tetrahydrofuran, tert-butanol, dichloromethane, benzene, toluene, acetone, pentane, hexane, heptane, octane, and decane. The reaction temperature is 1-100°C, preferably 20-50°C, and most preferably 25-40°C. The reaction time is 1-10h, preferably 2-8h, and more preferably 3-5h.

[0037] The reaction of the nickel source and the organic amine ligand of the present invention can be carried out under stirring conditions, and the mixture after the reaction is filtered, washed and dried to obtain the amine complex nickel.

[0038] In one embodiment, the tertiary alcohol alkali metal salt is a tertiary butyl alcohol alkali metal salt or a tertiary amyl alcohol alkali metal salt, specifically, it can be at least one of potassium tertiary butyl alcohol, sodium tertiary butyl alcohol, lithium tertiary butyl alcohol, potassium tertiary amyl alcohol, sodium tertiary amyl alcohol, and lithium tertiary amyl alcohol, preferably potassium tertiary butyl alcohol and sodium tertiary butyl alcohol. The reaction of the amine complex nickel and the tertiary alcohol alkali metal salt is carried out in an organic solvent, such as N-methyl pyrrolidone, dioxane, tetrahydrofuran, tertiary butyl alcohol, dichloromethane, benzene, toluene, acetone, pentane, hexane, heptane, octane, decane, etc., preferably THF, dichloromethane, and dioxane.

[0039] In one embodiment, the amine complex nickel is first mixed with an organic solvent, and then a tertiary alcohol alkali metal salt is added and reacted under stirring, the reaction temperature is, for example, 1-100° C., and the reaction time is, for example, 1-48 hours. After the reaction, the mixture is filtered, washed, and dried to obtain a transition metal catalyst. The structure of the transition metal catalyst has been described above and will not be repeated here.

[0040] In one embodiment, the molar ratio of the amine complex nickel to the tertiary alcohol alkali metal salt is 1:1 to 1:10, preferably 1:1 to 1:5, and most preferably 1:1 to 1:2.

[0041] The catalyst of the present invention can be used for catalytic preparation of linear alpha-olefins, and is particularly suitable for preparation of linear alpha-olefins with a high carbon number.

[0042] In one embodiment, the preparation of the linear α-olefin of the present invention comprises the following steps, wherein the transition metal catalyst is the transition metal catalyst described above:

[0043] Step 1, mixing a linear internal olefin with an alkyl aluminum compound, and causing an isomerization reaction and an alkyl substitution reaction under the action of a transition metal catalyst to obtain a substitution alkyl aluminum compound;

[0044] Step 2: mixing the substituted alkyl aluminum compound with the first linear α-olefin, and causing an alkyl substitution reaction under the action of the transition metal catalyst to obtain the linear α-olefin.

[0045] The preparation process of the linear α-olefin of the present invention is carried out under the protection of an inert atmosphere. The inert gas is, for example, nitrogen, argon, etc., which is not particularly limited in the present invention.

[0046] In one embodiment, the straight-chain internal olefin of the present invention has 5-20 carbon atoms, and the position of the double bond is any position other than the terminal position, for example, at least one of 2-pentene, 2-hexene, 3-hexene, 2-heptene, 3-heptene, 2-octene, 3-octene, 4-octene, 2-decene, 3-decene, 4-decene, 5-decene, 2-dodecene, 3-dodecene, 4-dodecene, 5-dodecene, 6-dodecene, etc.

[0047] In one embodiment, the alkyl aluminum compound of the present invention is tri-n-alkyl aluminum, that is, aluminum is connected to three alkyl groups, and the alkyl groups are linear structures, and the three alkyl groups can be the same or different. In another embodiment, the alkyl group in the tri-n-alkyl aluminum has 2-10 carbon atoms, preferably triethyl aluminum, tri-n-propyl aluminum, tri-n-butyl aluminum, tri-n-hexyl aluminum, tri-n-octylaluminum, tri-n-octadecyl aluminum. More preferably, triethyl aluminum, tri-n-propyl aluminum, and tri-n-hexyl aluminum.

[0048] In one embodiment, in step 1, the molar ratio of the linear internal olefin to the alkyl aluminum compound is 1:1-200:1, preferably 2:1-100:1; the content of the transition metal catalyst in the reaction system is 1-1000 ppm, preferably 10-500 ppm, and most preferably 20-100 ppm; the temperature of the isomerization reaction and the alkyl substitution reaction is 20°C to 200°C, and the time is 0.1-2 hours. After the reaction in step 1, at least one alkyl group in the alkyl aluminum compound is replaced by the alkyl group corresponding to the linear internal olefin, and the alkyl group corresponding to the linear internal olefin refers to the alkyl group generated after the double bond of the linear internal olefin is saturated.

[0049] In step 1 of the present invention, the reaction of the linear internal olefin and the alkyl aluminum compound is carried out in an organic solvent, such as tetrahydrofuran.

[0050] In one embodiment, the first linear α-olefin of the present invention is a low carbon number linear α-olefin, the carbon number of which is, for example, 2-20, such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-octadecene, preferably ethylene, propylene, 1-butene, 1-hexene, 1-octene. The carbon number of the first linear α-olefin is different from that of the linear α-olefin. In one embodiment, the carbon number of the linear α-olefin is greater than that of the first linear α-olefin, and the carbon number of the linear α-olefin is the same as that of the linear internal olefin.

[0051] In one embodiment, in step 2, the content of the transition metal catalyst in the reaction system is 1-1000ppm, preferably 10-500ppm, and most preferably 20-50ppm; the temperature of the alkyl replacement reaction in step 2 is -10°C to 200°C, preferably 0-100°C, and particularly preferably 20-100°C, and the time is 30 seconds to 2 hours, preferably 1-30min, so as to reduce the occurrence of side reactions.

[0052] In one embodiment, the reaction of the alkyl aluminum compound and the first linear α-olefin in step 2 is carried out in an organic solvent, such as tetrahydrofuran. After the reaction is completed, a lead naphthenate poisoning agent is added, sulfuric acid is used for quenching, and then the alkyl aluminum is completely quenched with a quenching agent such as ethanol, and the organic phase is analyzed by GC to determine the content of the linear α-olefin formed as the target product.

[0053] In one embodiment, the molar ratio of the first linear α-olefin to the linear internal olefin is greater than or equal to 3:1, preferably 3-100:1.

[0054] In the present invention, a linear internal olefin reacts with an alkyl aluminum compound to obtain a substituted alkyl aluminum compound. The substituted alkyl aluminum compound may be an alkyl aluminum compound in which one alkyl group is substituted, two alkyl groups are substituted, three alkyl groups are substituted, or a mixture in which one, two, or three alkyl groups are substituted, and the present invention is not particularly limited thereto. In the present invention, the obtained substituted alkyl aluminum compound can be an alkyl aluminum compound in which three alkyl groups are substituted by controlling the reaction conditions.

[0055] In addition, the mixture after the reaction of the linear internal olefin and the alkyl aluminum compound in step 1 of the present invention can be separated to obtain a relatively pure substituted alkyl aluminum compound or substituted alkyl aluminum compound to participate in the reaction in step 2; or the reaction mixture can be directly used for the reaction in step 2 without separation, in which case, there is no need to add an additional transition metal catalyst.

[0056] The technical solution of the present invention will be described in detail below through specific embodiments.

[0057] 1.1 General procedures and characterization

[0058] All chemicals used in the preparations were from commercial sources and used without further purification unless otherwise stated.

[0059] All manipulations with the catalyst system were performed under argon atmosphere. All reagents used were dried using standard procedures.

[0060] Liquid chemicals are stored separately (final water content ≤ 10 ppm) through Na wire or other drying materials and 4 angstrom molecular sieves.

[0061] 1-Hexene, THF, tri-n-alkylaluminum (1M), heptane and other chemicals were purchased from commercial companies such as Macklin and Aladdin and used after further purification. The obtained products were characterized by gas chromatography.

[0062] 1.2 Preparation of tertiary alkoxide nickel transition metal isomerization / replacement catalysts

[0063] (1) In a glove box protected by argon or other inert gas, weigh 3.9 g of anhydrous nickel chloride, add 30 ml of THF, and then add 4.5 ml of tetramethylethylenediamine, and stir at room temperature for 8 hours to synthesize tetramethylethylenediamine nickel dichloride. After drying, tetramethylethylenediamine nickel dichloride is mixed with 3.366 g of potassium tert-butoxide, which quickly turns into a blue insoluble solid. After washing and drying, the catalyst 1 is collected and used for later use.

[0064] (2) In a glove box protected by argon, 2.9 g of anhydrous nickel fluoride was weighed, 30 ml of THF was added, and then 4.5 ml of tetramethylbutylene diamine was added, and the mixture was stirred at 40° C. for 3 h to synthesize tetramethylbutylene diamine nickel difluoride. The tetramethylbutylene diamine nickel difluoride was dried and mixed with 6.6 g of sodium tert-amyl alcohol, which quickly turned into a blue insoluble solid. After washing and drying, the catalyst 2 was collected and used for later use.

[0065] (3) In a glove box protected by argon, 6.54 g of anhydrous nickel bromide was weighed, 30 ml of dichloromethane was added, and then 2 ml of ethylenediamine was added, and the mixture was stirred at 25° C. for 5 h to synthesize ethylenediamine nickel dibromide. The ethylenediamine nickel dibromide was dried and mixed with 2.883 g of sodium tert-butoxide, which quickly turned into a blue insoluble solid. After washing and drying, the catalyst 3 was collected and used for later use.

[0066] Example 1: Preparation of 1-hexene from 3-hexene

[0067] In a glove box protected by argon, 10 ml of 3-hexene, 10 ml of tetrahydrofuran, 5 ml of triethylaluminum, and the above-prepared catalyst 1 were added to a pressure-resistant glass bottle, and the content of the catalyst 1 was 20 ppm of the whole system. After reacting at 30°C for 15 minutes, tri-n-hexylaluminum was separated and set aside.

[0068] In a glove box protected by argon, add the above-separated tri-n-hexyl aluminum to a pressure-resistant glass bottle, introduce ethylene and propylene (ethylene 14g, propylene 21g) in a molar ratio of 1:1, add 10ml of tetrahydrofuran, add the above-prepared catalyst 1, and the content of the catalyst in the entire reaction system is 50ppm. React at 90℃ for 30min, add an excess of lead cyclopentaneate poisoning agent, and quench with sulfuric acid. Take the above-mentioned mixed material that has just been poisoned and cooled, and completely quench the alkyl aluminum with a quenching agent such as ethanol, analyze the organic phase with GC, determine the content of 1-hexene, and calculate the yield of 1-hexene to be 53%.

[0069] Example 2: Preparation of 1-decene from 5-decene

[0070] In a glove box protected by argon, add 5 ml of 5-decene, 10 ml of tetrahydrofuran, 5 ml of tri-n-hexyl aluminum, and the above-prepared catalyst 2 to a pressure-resistant glass bottle, the content of which is 20 ppm of the whole system. After reacting at 50°C for 30 minutes, separate the tri-n-decyl aluminum for later use.

[0071] In a glove box protected by argon, add the above-separated tri-n-decyl aluminum, 10 ml of 1-hexene, 10 ml of tetrahydrofuran, and the above-prepared catalyst 2 to a pressure-resistant glass bottle, and the content of the catalyst in the entire reaction system is 50 ppm. React at 90°C for 30 minutes, add an excess of lead cyclopentaneate poisoning agent, and quench with sulfuric acid. Take the above-mentioned mixed material that has just been poisoned and cooled, and completely quench the alkyl aluminum with a quenching agent such as ethanol. Analyze the organic phase with GC, determine the content of 1-decene, and calculate the yield of 1-decene to be 49%.

[0072] Example 3: Preparation of 1-hexene from 2-hexene and 3-hexene

[0073] In a glove box protected by argon or other inert gas, add 5 ml of 2-hexene, 5 ml of 3-hexene, 10 ml of tetrahydrofuran, 5 ml of triethylaluminum, and the above-prepared catalyst 3 to a specific reaction apparatus, the content of which is 100 ppm of the whole system. After reacting at 80°C for 1 hour, separate the tri-n-hexylaluminum for use.

[0074] In a glove box protected by argon, add the above-separated tri-n-hexyl aluminum to a pressure-resistant glass bottle, introduce ethylene in a molar ratio of five parts, add 10 ml of tetrahydrofuran, add the above-prepared catalyst 3, and the content of the catalyst in the entire reaction system is 50 ppm. React at 90°C for 15 minutes, add an excess of lead cyclopentaneate poisoning agent, and quench with sulfuric acid. Take the above-mentioned mixed material that has just been poisoned and cooled, and completely quench the alkyl aluminum with a quenching agent such as ethanol. Analyze the organic phase with GC, determine the content of 1-hexene, and calculate the yield of 1-hexene to be 48%.

[0075] Example 4: Preparation of 1-octene from 4-octene

[0076] In a glove box protected by argon, add 20 ml of 4-octene, 10 ml of THF, 3 ml of tri-n-hexyl aluminum, and the above-prepared catalyst 1 to a pressure-resistant glass bottle, the content of which is 100 ppm of the whole system. After reacting at 120°C for 2 hours, separate the tri-n-octyl aluminum for later use.

[0077] In a glove box protected by argon, add the above-separated tri-n-octylaluminum, 10 ml of 1-pentene, 10 ml of tetrahydrofuran, and the above-prepared catalyst 1 to a pressure-resistant glass bottle, and the content of the catalyst in the entire reaction system is 30 ppm. React at 60°C for 15 minutes, add an excess of lead cyclopentaneate poisoning agent, and quench with sulfuric acid. Take the above-mentioned mixed material that has just been poisoned and cooled, and completely quench the alkyl aluminum with a quenching agent such as ethanol. Analyze the organic phase with GC, determine the content of 1-octene, and calculate the yield of 1-octene to be 50%.

[0078] Example 5: Preparation of 1-decene from 5-decene

[0079] In a glove box protected by argon, add 10 ml of 5-decene, 10 ml of tetrahydrofuran, 2 ml of tri-n-hexyl aluminum, and the above-prepared catalyst 2 to a pressure-resistant glass bottle, the content of which is 100 ppm of the whole system. After reacting at 100°C for 30 minutes, separate the tri-n-decyl aluminum for later use.

[0080] In a glove box protected by argon, add the above-separated tri-n-decyl aluminum, 10 ml of 1-hexene, 10 ml of tetrahydrofuran, and the above-prepared catalyst 2 to a pressure-resistant glass bottle, and the content of the catalyst in the entire reaction system is 20 ppm. React at 90°C for 10 minutes, add an excess of lead cyclopentaneate poisoning agent, and quench with sulfuric acid. Take the above-mentioned mixed material that has just been poisoned and cooled, and completely quench the alkyl aluminum with a quenching agent such as ethanol. Analyze the organic phase with GC, determine the content of 1-decene, and calculate the yield of 1-decene to be 51%.

[0081] Comparative Example: Preparation of 1-decene from 5-decene

[0082] In a glove box protected by argon, add 10 ml of 5-decene, 10 ml of tetrahydrofuran, 2 ml of tri-n-hexyl aluminum, and nickel acetylacetonate to a pressure-resistant glass bottle, the content of which is 100 ppm of the whole system. After reacting at 100°C for 30 minutes, separate the tri-n-decyl aluminum for later use.

[0083] In a glove box protected by argon, add the above-separated tri-n-decyl aluminum, 10 ml 1-hexene, 10 ml tetrahydrofuran, and nickel cyclohexane acid to a pressure-resistant glass bottle. The catalyst content in the entire reaction system is 40 ppm. React at 90°C for 10 minutes, add an excess of lead cyclohexane acid poisoning agent, and quench with sulfuric acid. Take the above-mentioned mixed material that has just been poisoned and cooled, and completely quench the alkyl aluminum with a quenching agent such as ethanol. Analyze the organic phase with GC, determine the content of 1-decene, and calculate the yield of 1-decene to be 35%.

[0084] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a linear α-olefin, characterized in that: The steps include: Step 1, mixing a linear internal olefin with an alkyl aluminum compound, and causing an isomerization reaction and an alkyl substitution reaction under the action of a transition metal catalyst to obtain a substitution alkyl aluminum compound; Step 2, mixing the substituted alkyl aluminum compound with the first linear α-olefin, and causing an alkyl substitution reaction under the action of the transition metal catalyst to obtain the linear α-olefin; Wherein, the structural formula of the transition metal catalyst is: (CH3)2[CH3(CH2) n ]CO-Ni*xMX; M is an alkali metal, X is a halogen, x is in the range of 0.5-2, and n is 0, 1 or 2.

2. A method for preparing a linear α-olefin, characterized in that: The steps include: Step 1, mixing a linear internal olefin with an alkyl aluminum compound, and causing an isomerization reaction and an alkyl substitution reaction under the action of a transition metal catalyst to obtain a substitution alkyl aluminum compound; Step 2, mixing the substituted alkyl aluminum compound with the first linear α-olefin, and causing an alkyl substitution reaction under the action of the transition metal catalyst to obtain the linear α-olefin; Wherein, the preparation method of the transition metal catalyst comprises the following steps: Step a, allowing the nickel source to react with the organic amine ligand to obtain an amine complex nickel; Step b, reacting the amine complex nickel with a tertiary alcohol alkali metal salt to obtain a transition metal catalyst.

3. The method for preparing a linear α-olefin according to claim 1 or 2, characterized in that: The first linear α-olefin has a different carbon number from the linear α-olefin.

4. The method for preparing a linear α-olefin according to claim 1 or 2, characterized in that: The linear α-olefin has a carbon number greater than the carbon number of the first linear α-olefin.

5. The method for preparing a linear α-olefin according to claim 1 or 2, characterized in that: The linear internal olefin has 5 to 20 carbon atoms; the alkyl aluminum compound is tri-n-alkyl aluminum, and the alkyl group in the tri-n-alkyl aluminum has 2 to 10 carbon atoms; and the molar ratio of the linear internal olefin to the alkyl aluminum compound is 1:1 to 200:

1.

6. The method for preparing a linear α-olefin according to claim 1 or 2, characterized in that: In step 1, the content of the transition metal catalyst in the reaction system is 1-1000 ppm; in step 1, the reaction temperature is 20° C. to 200° C., and the reaction time is 0.1-2 hours.

7. The method for preparing straight-chain α-olefin according to claim 1 or 2, characterized in that: The carbon number of the first linear α-olefin is 2-20, and the carbon number of the linear α-olefin is the same as the carbon number of the linear internal olefin; in step 2, the content of the transition metal catalyst in the reaction system is 1-1000ppm; the reaction temperature in step 2 is -10°C to 200°C, and the reaction time is 30 seconds to 2 hours.

8. The method for preparing straight-chain α-olefin according to claim 2, characterized in that: The nickel source is a nickel (II) compound, and the organic amine ligand is an alkyl diamine compound or an alkyl diamine carboxylic acid, wherein the alkyl diamine compound has 2-12 carbon atoms, and the alkyl diamine carboxylic acid has 3-12 carbon atoms.

9. The method for preparing straight-chain α-olefin according to claim 2, characterized in that: The nickel source is at least one of anhydrous nickel chloride, anhydrous nickel bromide, anhydrous nickel fluoride, and dimethoxyethane nickel dichloride; the organic amine ligand is at least one of ethylenediamine, propylenediamine, butylenediamine, ethylenediaminetetraacetic acid, tetramethylethylenediamine, tetramethylpropylenediamine, and tetramethylbutylenediamine; the molar ratio of the nickel source to the organic amine ligand is 1:1-1:10; the nickel source and the organic amine ligand are reacted in an organic solvent, the organic solvent is at least one of N-methylpyrrolidone, dioxane, tetrahydrofuran, tert-butanol, dichloromethane, benzene, toluene, acetone, pentane, hexane, heptane, octane, and decane, the reaction temperature is 1-100°C, and the reaction time is 1-10h.

10. The method for preparing linear α-olefins according to claim 2, characterized in that: The tertiary alcohol alkali metal salt is at least one of potassium tert-butoxide, sodium tert-butoxide, lithium tert-butoxide, potassium tert-amyl alcohol, sodium tert-amyl alcohol, and lithium tert-amyl alcohol; the molar ratio of the amine complex nickel to the tertiary alcohol alkali metal salt is 1:1-1:10; the amine complex nickel and the tertiary alcohol alkali metal salt are reacted in an organic solvent, and the organic solvent is at least one of N-methylpyrrolidone, dioxane, tetrahydrofuran, tert-butanol, dichloromethane, benzene, toluene, acetone, pentane, hexane, heptane, octane, and decane; the reaction temperature of the amine complex nickel and the tertiary alcohol alkali metal salt is 1-100°C, and the reaction time is 1-48h.