Long-chain linear alpha-olefin and preparation method thereof

Abstract

The invention provides long-chain linear alpha-olefin and a preparation method thereof. The preparation method comprises the following steps: step 1, carrying out oligomerization reaction on ethylene under the action of a main catalyst, a catalyst promoter and a chain transfer agent; step 2, after the oligomerization reaction in the step 1 is finished, mixing a reaction mixture with a chain elimination agent to carry out chain elimination reaction, and then stopping the chain elimination reaction to obtain long-chain linear alpha-olefin; wherein the chain transfer agent is diethyl zinc and / or diethyl magnesium. According to the preparation method of the long-chain linear alpha-olefin, the vinyl polymerization activity is relatively high, the alpha-olefin selectivity is relatively high, the linear selectivity is relatively high, and the oligomerization product is C8-C30 linear alpha-olefin. Besides, the oligomerization product obtained by the method disclosed by the invention is narrow in distribution, and the distribution of the product is not Schulz-Flory distribution but obeys Poisson distribution, so that the yield of the long-chain linear carbon number alpha-olefin is higher, and the selectivity of the long-chain C12-C20 linear carbon number alpha-olefin can reach 85mol%.

Description

Technical Field

[0001] The invention relates to the field of long-chain linear alpha-olefin preparation, and in particular to a method for preparing long-chain linear alpha-olefin by selective polymerization of ethylene and the obtained long-chain linear alpha-olefin. Background Art

[0002] In the prior art, although the method of synthesizing a series of α-olefins by oligomerization of ethylene can prepare linear α-olefins with high selectivity under the action of a catalyst, including α-olefin selectivity of more than 98% and linear selectivity of 100%, the obtained oligomerization products usually obey the Schulz-Flory distribution (that is, from C4 onwards, as the carbon number increases, the content of the oligomerization products decreases). Although long-chain linear α-olefins above C8 can be obtained by distillation, the yield of long-chain linear α-olefins above C8 is particularly low, especially the longer the linear α-olefin, the lower the yield. Therefore, on the basis of ensuring high α-olefin selectivity and linear selectivity, it is of great significance to further improve the selectivity of carbon number, especially the selectivity of long-chain carbon, and prepare long-chain linear α-olefins with high yield.

[0003] Patent CN 112920227 A discloses a metallocene compound containing an indenoindole structure, a preparation method, an application thereof, and a preparation method of α-olefins. The metallocene compound containing an indenoindole structure provided by the invention can be used as a catalyst for catalytic synthesis of α-olefins, and can synthesize α-olefins with high carbon number with high activity and high selectivity. The main components of the product are 1-octene, 1-decene and 1-dodecene, and it does not contain or contains less α-olefins with higher carbon number.

[0004] Patent CN 105797773 A discloses a novel linear alpha olefin catalyst and its preparation process and use. The catalyst composition is composed of a main catalyst and a co-catalyst, wherein the main catalyst is an iron-based imine complex, and the co-catalyst is methylaluminoxane, triisobutylaluminum, borane and GaCl3. The catalyst composition is used to catalyze the polymerization of ethylene to prepare linear alpha olefins, with a linear alpha olefin selectivity greater than 96%, and a carbon number distribution of C4-C 28 , among which C6-C 20 The catalyst of the invention has a stable structure, can be used for ethylene polymerization, has high catalytic efficiency, is easy to operate in the preparation method, has high yield, is easy to obtain raw materials, has low cost, has little environmental pollution, and is easy to industrialize. However, the products are concentrated in C6-C 20 , it is difficult to mainly obtain linear α-olefins with higher carbon numbers. Summary of the invention

[0005] The main purpose of the present invention is to provide a long-chain linear α-olefin and a preparation method thereof, so as to overcome the defects of the prior art that the α-olefin mixture prepared by ethylene polymerization obeys the Schulz-Flory distribution and has low selectivity for high-carbon number α-olefins.

[0006] In order to achieve the above object, the present invention provides a method for preparing long-chain linear α-olefins by selective oligomerization of ethylene, comprising the following steps:

[0007] Step 1, subjecting ethylene to an oligomerization reaction under the action of a main catalyst, a co-catalyst and a chain transfer agent;

[0008] Step 2, after the polymerization reaction in step 1 is completed, the reaction mixture is mixed with a chain elimination agent to carry out a chain elimination reaction, and then the chain elimination reaction is terminated to obtain a long-chain linear α-olefin;

[0009] Wherein, the chain transfer agent is diethyl zinc and / or diethyl magnesium.

[0010] The method for preparing long-chain linear alpha-olefins by selective polymerization of ethylene of the present invention comprises the following steps: the main catalyst is a diimine pyridine iron complex; and the co-catalyst is methylaluminoxane or modified methylaluminoxane.

[0011] The method for preparing long-chain linear α-olefins by selective polymerization of ethylene according to the present invention, wherein the main catalyst has a structure of formula I:

[0012]

[0013] Wherein, R1 is an alkyl group having 1 to 10 carbon atoms.

[0014] In the method for preparing long-chain linear α-olefins by selective polymerization of ethylene described in the present invention, the molar ratio of the co-catalyst to the main catalyst is 500-1000:1.

[0015] In the method for preparing long-chain linear α-olefins by selective polymerization of ethylene described in the present invention, the molar ratio of the chain transfer agent to the main catalyst is 500-1000:1.

[0016] The method for preparing long-chain linear α-olefins by selective polymerization of ethylene of the present invention comprises the following steps: in step 1, the pressure of ethylene is 1 to 50 atm, the temperature of the polymerization reaction is 10 to 100° C., and the time is 10 min to 60 min.

[0017] The method for preparing long-chain linear alpha-olefins by selective polymerization of ethylene of the present invention, wherein the chain eliminator is nickel acetylacetonate or nickel dipyridine, and the molar ratio of the chain eliminator to the main catalyst is 20 to 200:1.

[0018] The method for preparing long-chain linear α-olefins by selective polymerization of ethylene of the present invention comprises the following steps: the temperature of the chain elimination reaction is 10-100° C., and the pressure of ethylene in the chain elimination reaction is 1-5 atm.

[0019] The method for preparing long-chain linear alpha-olefins by selective oligomerization of ethylene of the present invention comprises adding a hydrochloric acid aqueous solution to terminate the chain elimination reaction, wherein the hydrochloric acid aqueous solution is hydrochloric acid acidified ethanol with a hydrochloric acid mass fraction of 5-15%.

[0020] In order to achieve the above object, the present invention also provides a long-chain linear α-olefin obtained by the above preparation method, wherein the long-chain linear α-olefin is C8~C 30 Linear α-olefins, C 12 ~C 20 The selectivity for linear alpha olefins is greater than or equal to 40 mol%.

[0021] Beneficial effects of the present invention:

[0022] (1) In the method for preparing long-chain linear α-olefins of the present invention, the ethylene polymerization activity is high, the α-olefin selectivity is high, the linear selectivity is high, and the oligomerization product is C8 to C 30 In addition, the distribution of the oligomerization product obtained by the method of the present invention is narrow, and the product distribution is not Schulz-Flory distribution, but obeys Poisson distribution (please refer to Figure 2 ), so the yield of long-chain linear α-olefins is higher, and long-chain C 12 ~C 20 The selectivity of linear α-olefins can reach 85 mol%.

[0023] (2) The polymerization product obtained by the method of the present invention contains almost no high molecular weight polymer, which can avoid blockage in the industrial production process and the complex process of product separation. At the same time, the main catalyst has high activity, high metal abundance, and abundant sources, which is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a visual representation of the linear alpha olefin prepared in Example 4.

[0025] Figure 2 Schematic diagram of Schulz-Flory distribution and Poisson distribution of linear α-olefin products.

[0026] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the linear α-olefin prepared in Example 4.

[0027] Figure 4 This is the carbon nuclear magnetic resonance spectrum of the linear α-olefin prepared in Example 5.

[0028] Figure 5 This is a gas chromatogram of the linear α-olefin prepared in Example 4. DETAILED DESCRIPTION

[0029] 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.

[0030] The present invention provides a method for preparing long-chain linear α-olefins by selective polymerization of ethylene, comprising the following steps:

[0031] Step 1, subjecting ethylene to an oligomerization reaction under the action of a main catalyst, a co-catalyst and a chain transfer agent;

[0032] Step 2, after the polymerization reaction in step 1 is completed, the reaction mixture is mixed with a chain elimination agent to carry out a chain elimination reaction, and then the chain elimination reaction is terminated to obtain a long-chain linear α-olefin;

[0033] Wherein, the chain transfer agent is diethyl zinc and / or diethyl magnesium.

[0034] The present invention adopts diethyl zinc and / or diethyl magnesium as a chain transfer agent to carry out a directional transfer of the chain length of the active center, thereby achieving the purpose of increasing the production of C8 and above alpha-olefins.

[0035] In one embodiment, the method for preparing long-chain linear α-olefins by selective polymerization of ethylene is carried out in a reactor, such as a quartz, glass, or stainless steel reactor, with a volume of, for example, 0.1-5 L, which is not particularly limited in the present invention.

[0036] In one embodiment, the present invention first heats the reactor to a certain temperature, such as 100-120° C., uses cyclohexane to heat wash the reactor for a certain time, and then performs steps 1-2. The heat washing time is, for example, 10-50 minutes.

[0037] In one embodiment, the main catalyst of the present invention is a bis-imine pyridine iron complex; in another embodiment, the bis-imine pyridine iron complex has the following structure I:

[0038]

[0039] Wherein, R1 is an alkyl group having 1 to 10 carbon atoms.

[0040] In another embodiment, R1 is an alkyl group having 1-8 carbon atoms or having 1-6 carbon atoms or having 1-4 carbon atoms. In another embodiment, R1 is a methyl group, an ethyl group, an isopropyl group, or a tert-butyl group. In yet another embodiment, R1 is an isopropyl group or a tert-butyl group.

[0041] The main catalyst of the invention has high catalytic activity, high metal abundance and abundant iron sources.

[0042] In one embodiment, the cocatalyst of the present invention is an alkylaluminoxane or a modified alkylaluminoxane, such as methylaluminoxane or a modified methylaluminoxane. The present invention does not specifically limit the modification of the alkylaluminoxane, and any conventional modification of the alkylaluminoxane in the art may be used.

[0043] In one embodiment, the molar ratio of the co-catalyst to the main catalyst of the present invention is 500-1000:1, and the molar ratio of the chain transfer agent to the main catalyst is 500-1000:1. In the oligomerization reaction, the ethylene pressure is 1-50 atm, preferably 5-20 atm. The temperature of the oligomerization reaction is 10-100° C., preferably 30-70° C. The time of the oligomerization reaction is 10 min-60 min, for example, 30 min.

[0044] After the polymerization reaction is completed, the ethylene pressure is released and the ethylene is mixed with the chain elimination agent to carry out the chain elimination reaction.

[0045] In one embodiment, the chain elimination agent is at least one of nickel acetylacetonate and nickel bipyridine, and the molar ratio of the chain transfer agent to the main catalyst is 20 to 200:1. The temperature of the chain elimination reaction is 10 to 100°C, preferably 30 to 70°C; the chain elimination reaction time is 1 to 5 hours. In another embodiment, a substance that terminates the polymerization activity of the main catalyst, such as tetrahydrofuran, is also added to the chain elimination reaction.

[0046] In one embodiment, after the polymerization reaction is completed, the ethylene pressure is released to 1 to 5 atm, preferably 3 to 5 atm.

[0047] After the chain elimination reaction is completed, a hydrochloric acid aqueous solution is added to terminate the reaction, the organic phase is extracted and separated, and the solvent is then distilled off to obtain a long-chain linear α-olefin.

[0048] In one embodiment, the hydrochloric acid aqueous solution is hydrochloric acid-acidified ethanol with a hydrochloric acid mass fraction of 5-15%.

[0049] The method of the present invention can improve the selectivity of long-chain linear α-olefins above C8 in the product, and the obtained long-chain linear α-olefins are C8~C 30 Linear α-olefins, C 12 ~C 20 The selectivity of linear α-olefins is greater than or equal to 40 mol %, and may even reach 85 mol %.

[0050] In the method of the present invention, the ethylene polymerization activity is as high as 1.44×10 7 g / (mol Fe h), and the selectivity is also high, among which the α-olefin selectivity is>98mol%, and the linear selectivity is 100mol%. The distribution of the polymerization products is narrow, and the product distribution is not Schulz-Flory distribution, but obeys Poisson distribution, so the yield of long-chain linear α-olefins is higher.

[0051] At the same time, no high molecular weight polymers are produced in the polymerization products, which can avoid blockages in the industrial production process and the complex process of product separation. At the same time, the iron catalyst has high activity, high metal abundance and abundant sources, which is conducive to industrial production.

[0052] The technical solution of the present invention is further described below in conjunction with specific examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually carried out according to conventional conditions in the art or according to the conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are all raw materials and reagents that can be obtained from commercial channels such as conventional markets. Any non-substantial changes and substitutions made by those skilled in the art on the basis of the present invention belong to the scope of protection claimed by the present invention.

[0053] In order to clearly describe the compounds and complexes in the examples, the following are described:

[0054]

[0055] Fe1 has a structure of formula I, and R1 is a methyl group.

[0056] Fe2 has the structure of Formula I, and R1 is ethyl.

[0057] Fe3 has a structure of formula I, and R1 is isopropyl.

[0058] Fe4 has a structure of formula I, and R1 is tert-butyl.

[0059] 1. Preparation of Bis-Imine Pyridine Iron Complex

[0060] The bis-imine pyridine iron complexes Fe1, Fe2, and Fe3 were synthesized according to the method reported in Journal of Molecular Catalysis A: Chemical 2002, 179, 155. The synthesis of the bis-imine pyridine iron complex Fe4 was based on the synthesis of the bis-imine pyridine iron complex Fe1, except that 2,6-di-tert-butylaniline was used instead of 2,6-dimethylaniline.

[0061] Fe1 synthesis: synthesized according to the method reported in Journal of Molecular Catalysis A: Chemical 2002, 179, 155.

[0062] Fe2 synthesis: synthesized according to the method reported in Journal of Molecular Catalysis A: Chemical 2002, 179, 155.

[0063] Fe3 synthesis: synthesized according to the method reported in Journal of Molecular Catalysis A: Chemical 2002, 179, 155.

[0064] Fe4 synthesis: 1.50g (9.2mmol) 2,6-diacetylpyridine, 3.94g (19.2mmol) 2,6-di-tert-butylaniline, 80mL toluene and a catalytic amount of p-toluenesulfonic acid were added to a branched bottle, and the water was separated and refluxed overnight. After cooling to room temperature, the toluene was removed by rotary evaporation, and the ligand was obtained by recrystallization from ethanol. Weigh 1.01g (1.89mmol) of the ligand and 0.24g (1.89mmol) of FeCl2 were transferred to a Schlenk bottle through a three-way tube under a nitrogen atmosphere, and 40mL of anhydrous tetrahydrofuran was injected into the branch. Stir at room temperature for 12h, concentrate the reaction solution, filter the product solution, add anhydrous ether to wash three times, and dry to obtain 0.93g of dark blue solid with a yield of 75%. Elemental analysis (C 37 H 51 Cl2N3Fe, %) theoretical value: C, 66.87; H, 7.74; N, 6.32. Found value: C, 66.61; H, 7.65; N, 6.16. ESI-MS (m / z): 663.58 [M] + .

[0065] 2. Preparation of linear α-olefins by selective polymerization of ethylene

[0066] In the following examples, the polymerization activity is calculated by the mass of the final α-olefin, the amount of metallic iron catalyst used and the polymerization time (activity = α-olefin mass / (metallic iron catalyst molar amount × time)); the carbon number distribution of the prepared linear α-olefin is determined by gas chromatography, and the α-olefin selectivity is calculated by nuclear magnetic resonance hydrogen spectrum and gas chromatography; the linear selectivity is calculated by nuclear magnetic resonance hydrogen spectrum.

[0067] The following Examples 1-26 provide methods for preparing long-chain linear α-olefins by selectively polymerizing ethylene using an iron catalyst. The specific reaction steps are as follows:

[0068] The autoclave was heated to 150°C, dried at vacuum high temperature for 2h, and then the autoclave was slowly cooled to room temperature. The autoclave was replaced twice with ethylene and then maintained at positive pressure. 50mL of toluene solvent, a certain amount of cocatalyst, a certain amount of chain transfer agent and a certain amount of diiminopyridine iron catalyst were added to the autoclave. After balancing to the set temperature, a certain pressure of ethylene was introduced and the ethylene chain transfer polymerization reaction was carried out at a certain temperature for 30 minutes. After the polymerization reaction reached the set time, the introduction of ethylene was stopped, the ethylene pressure was adjusted to the chain elimination reaction pressure, 2mL of tetrahydrofuran (termination of iron polymerization active species) and a certain amount of chain elimination agent were added to the autoclave, and the chain elimination reaction was carried out at a certain ethylene pressure and a certain temperature for 2 hours. After the chain elimination reaction reached the set time, the introduction of ethylene was stopped, the pressure was slowly released, the autoclave was opened, the reaction system was terminated with a 5% hydrochloric acid aqueous solution by mass fraction, the liquid was washed with water, the organic phase was collected and dried, distilled, and purified by column chromatography to obtain a linear α-olefin product.

[0069] Embodiment 1:

[0070] ① Fe1 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0071] Embodiment 2:

[0072] ①Fe2 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4atm, temperature 50℃, time 2 hours.

[0073] Embodiment 3:

[0074] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0075] Embodiment 4:

[0076] ① Fe4 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0077] Figure 1 A visual image of the linear α-olefin prepared in Example 4, Figure 1 As shown, the product obtained by the method of the present invention is a colorless transparent liquid. Figure 3 The hydrogen nuclear magnetic resonance spectrum of the linear α-olefin prepared in Example 4 is Figure 3 It can be seen that the product is indeed linear α-olefin. Figure 5 The gas chromatogram of the linear α-olefin prepared in Example 4 is shown by Figure 5 It can be seen that the product distribution conforms to the Poisson distribution.

[0078] Embodiment 5:

[0079] ①Fe3 catalyst 1μmol, co-catalyst MMAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4atm, temperature 50℃, time 2 hours.

[0080] Figure 4 This is the carbon NMR spectrum of the linear α-olefin prepared in Example 5. The linear α-olefin is obtained through chain elimination reaction.

[0081] Embodiment 6:

[0082] ①Fe3 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 1000:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4atm, temperature 50℃, time 2 hours.

[0083] Embodiment 7:

[0084] ①Fe3 catalyst 1μmol, cocatalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent MgEt2, CTA / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4atm, temperature 50℃, time 2 hours.

[0085] Embodiment 8:

[0086] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 500:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0087] Embodiment 9:

[0088] ①Fe3 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 1000:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4atm, temperature 50℃, time 2 hours.

[0089] Embodiment 10:

[0090] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 10°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0091] Embodiment 11:

[0092] ①Fe3 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 30℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4atm, temperature 50℃, time 2 hours.

[0093] Embodiment 12:

[0094] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 50°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0095] Embodiment 13:

[0096] ①Fe3 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 100℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4atm, temperature 50℃, time 2 hours.

[0097] Embodiment 14:

[0098] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 1 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0099] Embodiment 15:

[0100] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 20 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0101] Embodiment 16:

[0102] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 50 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0103] Embodiment 17:

[0104] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel bipyridine, EA / Fe molar ratio = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0105] Embodiment 18:

[0106] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe molar ratio = 20:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0107] Embodiment 19:

[0108] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe molar ratio = 200:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours.

[0109] Embodiment 20:

[0110] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 10°C, time 2 hours.

[0111] Embodiment 21:

[0112] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 30°C, time 2 hours.

[0113] Embodiment 22:

[0114] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 70°C, time 2 hours.

[0115] Embodiment 23:

[0116] ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 100°C, time 2 hours.

[0117] Embodiment 24:

[0118] ①Fe3 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 1atm, temperature 50℃, time 2 hours.

[0119] Embodiment 25:

[0120] ①Fe3 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 3atm, temperature 50℃, time 2 hours.

[0121] Embodiment 26:

[0122] ①Fe3 catalyst 1μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5atm, temperature 70℃, time 30 minutes. ②Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 5atm, temperature 50℃, time 2 hours.

[0123] Comparative Example 1

[0124] No chain transfer agent, the rest is the same as Example 3. ① Fe3 catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. ② Chain elimination conditions: chain elimination agent nickel acetylacetonate, Ni / Fe molar ratio = 50:1, ethylene pressure 4 atm, temperature 50°C, time 2 hours. The products are all high molecular weight solid polymers, and no ethylene selective polymerization occurs.

[0125] Comparative Example 2

[0126] No chain eliminator, the rest is the same as in Example 3. Fe3 catalyst 1 μmol, cocatalyst MAO, Al / Fe molar ratio = 500:1, chain transfer agent ZnEt2, Zn / Fe molar ratio = 750:1, ethylene pressure 5 atm, temperature 70°C, time 30 minutes. The polymerization products are all saturated alkane products, and no olefin products are generated.

[0127]

[0128]

[0129]

[0130] The linear α-olefin products obtained in Examples 1-26 of the present invention conform to the Poisson distribution, and the C12-C20 selectivity is between 40-80%.

[0131] 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 long-chain linear α-olefins by selective oligomerization of ethylene, characterized in that: The steps include: Step 1, subjecting ethylene to an oligomerization reaction under the action of a main catalyst, a co-catalyst and a chain transfer agent; Step 2, after the polymerization reaction in step 1 is completed, the reaction mixture is mixed with a chain elimination agent to carry out a chain elimination reaction, and then the chain elimination reaction is terminated to obtain a long-chain linear α-olefin; Wherein, the chain transfer agent is diethyl zinc and / or diethyl magnesium.

2. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 1, characterized in that: The main catalyst is a diimine pyridine iron complex; the co-catalyst is methylaluminoxane or modified methylaluminoxane.

3. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 2, characterized in that: The main catalyst has a structure of formula I: Wherein, R1 is an alkyl group having 1 to 10 carbon atoms.

4. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 1, characterized in that: The molar ratio of the co-catalyst to the main catalyst is 500 to 1000:

1.

5. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 1, characterized in that: The molar ratio of the chain transfer agent to the main catalyst is 500 to 1000:

1.

6. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 1, characterized in that: In step 1, the ethylene pressure is 1 to 50 atm, the polymerization temperature is 10 to 100° C., and the time is 10 min to 60 min.

7. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 1, characterized in that: The chain eliminator is nickel acetylacetonate or nickel dipyridine, and the molar ratio of the chain eliminator to the main catalyst is 20 to 200:

1.

8. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 1, characterized in that: The temperature of the chain elimination reaction is 10-100° C., and the pressure of ethylene in the chain elimination reaction is 1-5 atm.

9. The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to claim 1, characterized in that: A hydrochloric acid aqueous solution is added to terminate the chain elimination reaction, wherein the hydrochloric acid aqueous solution is hydrochloric acid acidified ethanol with a hydrochloric acid mass fraction of 5-15%.

10. The long-chain linear α-olefin obtained by the preparation method according to any one of claims 1 to 9, characterized in that: The long-chain linear α-olefin is C8~C 30 Linear α-olefins, C 12 ~C 20 The selectivity for linear alpha olefins is greater than or equal to 40 mol%.

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