Long chain linear alpha-olefins and process for their preparation

Abstract

This invention provides a long-chain linear α-olefin and its preparation method. The preparation method includes the following steps: Step 1, ethylene is subjected to oligomerization reaction under the action of a main catalyst, a co-catalyst, and a chain transfer agent; Step 2, after the oligomerization reaction in Step 1 is completed, the reaction mixture is mixed with a chain eliminator 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 diethylzinc and / or diethylmagnesium. In the preparation method of the long-chain linear α-olefin of this invention, the ethylene polymerization activity is high, the α-olefin selectivity is high, the linear selectivity is high, and the oligomerization product is C8-C9. 30 The method yields linear α-olefins. Furthermore, the oligomers obtained by this invention have a narrow distribution, and the product distribution is not a Schulz-Flory distribution but follows a Poisson distribution. Therefore, the yield of long-chain linear α-olefins is higher, and the long-chain C... 12 ~C 20 The selectivity for linear α-olefins with a carbon number of up to 85 mol% can be achieved.

Description

Technical Field

[0001] This invention relates to the field of long-chain linear α-olefin preparation, specifically to a method for preparing long-chain linear α-olefins by selective oligomerization of ethylene and the obtained long-chain linear α-olefins. Background Technology

[0002] In existing technologies, while the oligomerization of ethylene to synthesize a series of α-olefins can achieve high selectivity for linear α-olefins under catalysis, including over 98% α-olefin selectivity and 100% linear selectivity, the resulting oligomers typically follow a Schulz-Flory distribution (i.e., the oligomer content decreases with increasing carbon number from C4 onwards). Although distillation can yield long-chain linear α-olefins with C8 or more, the yield of these long-chain linear α-olefins is particularly low, especially for longer chains. Therefore, further improving carbon number selectivity, particularly the selectivity for longer-chain carbons, to achieve high yields of long-chain linear α-olefins while maintaining high α-olefin and linear selectivity is of great significance.

[0003] Patent CN 112920227 A discloses a metallocene compound containing an indendoindole structure, its preparation method, applications, and a method for preparing α-olefins. The metallocene compound containing an indendoindole structure provided by this invention can be used as a catalyst for the catalytic synthesis of α-olefins, and can synthesize high-carbon-number α-olefins with high activity and high selectivity. The main components of the product are 1-octene, 1-decene, and 1-dodecene, and it contains little or no α-olefins with higher carbon numbers.

[0004] Patent CN 105797773 A discloses a novel linear α-olefin catalyst, its preparation process, and its applications. The catalyst composition comprises a main catalyst and a co-catalyst, wherein the main catalyst is an iron-based imine coordination compound, and the co-catalyst is methylaluminoxane, triisobutylaluminum, borane, and GaCl3. This catalyst composition is used to catalyze the oligomerization of ethylene to prepare linear α-olefins, with a selectivity greater than 96% and a carbon number distribution between C4 and C6. 28 C6-C 20 Greater than 75%. The catalyst of this invention has a stable structure, can be used for ethylene oligomerization, has high catalytic efficiency, and its preparation method is simple, yields high, uses readily available raw materials, has low cost, low environmental pollution, and is easy to industrialize. However, the products are concentrated in C6-C. 20 It is difficult to obtain linear α-olefins with higher carbon numbers. Summary of the Invention

[0005] The main objective of this invention is to provide a long-chain linear α-olefin and its preparation method, so as to overcome the defects of existing technologies, such as the α-olefin mixtures prepared by ethylene oligomerization following the Schulz-Flory distribution and the low selectivity of high carbon number α-olefins.

[0006] To achieve the above objectives, the present invention provides a method for the selective oligomerization of ethylene to prepare long-chain linear α-olefins, comprising the following steps:

[0007] Step 1: Ethylene undergoes oligomerization under the action of a main catalyst, a co-catalyst, and a chain transfer agent;

[0008] Step 2: After the oligomerization reaction in step 1 is completed, the reaction mixture is mixed with a chain eliminator to carry out a chain elimination reaction, and then the chain elimination reaction is terminated to obtain a long-chain linear α-olefin.

[0009] The chain transfer agent is diethylzinc and / or diethylmagnesium.

[0010] The method for selective oligomerization of ethylene to prepare long-chain linear α-olefins according to the present invention, wherein the main catalyst is a bisimine pyridine iron complex; and the co-catalyst is methylaluminoxane or modified methylaluminoxane.

[0011] The method for selective oligomerization of ethylene to prepare long-chain linear α-olefins according to the present invention, wherein the main catalyst has the structure of Formula I:

[0012]

[0013] R1 is an alkyl group with 1-10 carbon atoms.

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

[0015] The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to the present invention, wherein 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 oligomerization of ethylene according to the present invention, wherein in step 1, the pressure of ethylene is 1-50 atm, the temperature of the oligomerization reaction is 10-100℃, and the time is 10-60 min.

[0017] The method for preparing long-chain linear α-olefins by selective oligomerization of ethylene according to the present invention, wherein the chain eliminator is nickel acetylacetonate or nickel bipyridine, 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 oligomerization of ethylene according to the present invention, wherein 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 α-olefins by selective oligomerization of ethylene according to the present invention includes adding an aqueous hydrochloric acid solution to stop the chain elimination reaction, wherein the aqueous hydrochloric acid solution is ethanol acidified with hydrochloric acid at a mass fraction of 5-15%.

[0020] To achieve the above objectives, the present invention also provides a long-chain linear α-olefin obtained by the above preparation method, wherein the long-chain linear α-olefin has a C8 to C96 configuration. 30 Linear α-olefins, C 12 ~C 20 The selectivity for linear α-olefins is greater than or equal to 40 mol%.

[0021] The beneficial effects of this invention are:

[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~C8. 30 Linear α-olefins. Furthermore, the oligomers obtained by the method of this invention have a narrow distribution, and the product distribution is not a Schulz-Flory distribution, but rather follows a Poisson distribution (see reference). Figure 2 Therefore, the yield of long-chain linear α-olefins is higher, and the long-chain C 12 ~C 20 The selectivity for linear α-olefins can reach 85 mol%.

[0023] (2) The oligomers obtained by the method of the present invention contain almost no high molecular weight polymers, which can avoid the blockage and complex process of product separation in the industrial production process. At the same time, the main catalyst has high activity, high metal abundance and abundant source, which is conducive to industrial production. Attached Figure Description

[0024] Figure 1 Visual image of the linear α-olefin prepared in Example 4.

[0025] Figure 2 This is a schematic diagram of the Schulz-Flory and Poisson distributions of linear α-olefin products.

[0026] Figure 3 The 1H NMR spectrum of the linear α-olefin prepared in Example 4.

[0027] Figure 4 The image shows the carbon NMR spectrum of the linear α-olefin prepared in Example 5.

[0028] Figure 5 The gas chromatogram of the linear α-olefin prepared in Example 4 is shown. Detailed Implementation

[0029] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution 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 embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0030] This invention provides a method for the selective oligomerization of ethylene to prepare long-chain linear α-olefins, comprising the following steps:

[0031] Step 1: Ethylene undergoes oligomerization under the action of a main catalyst, a co-catalyst, and a chain transfer agent;

[0032] Step 2: After the oligomerization reaction in step 1 is completed, the reaction mixture is mixed with a chain eliminator to carry out a chain elimination reaction, and then the chain elimination reaction is terminated to obtain a long-chain linear α-olefin.

[0033] The chain transfer agent is diethylzinc and / or diethylmagnesium.

[0034] This invention uses diethylzinc and / or diethylmagnesium as chain transfer agents to perform chain length-directed transfer of the active center, thereby achieving the goal of increasing the production of C8 and above α-olefins.

[0035] In one embodiment, the method for selective oligomerization of ethylene to prepare long-chain linear α-olefins according to the present invention is carried out in a reaction vessel, such as a quartz, glass, or stainless steel reaction vessel, with a volume of, for example, 0.1-5 L. The present invention does not impose any particular limitation.

[0036] In one embodiment, the present invention first heats the reaction vessel to a certain temperature, for example, 100-120°C, and then performs a hot wash with cyclohexane for a certain period of time before proceeding to steps 1-2. The hot wash time is, for example, 10-50 minutes.

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

[0038]

[0039] R1 is an alkyl group with 1-10 carbon atoms.

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

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

[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 particularly limit the modification of alkylaluminoxanes; conventional modifications of alkylaluminoxanes are applicable in the art.

[0043] In one embodiment, the molar ratio of the co-catalyst to the main catalyst is 500–1000:1, and the molar ratio of the chain transfer agent to the main catalyst is 500–1000:1. During 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 10–60 min, for example, 30 min.

[0044] After the oligomerization reaction is completed, the ethylene pressure is released, and the mixture is mixed with a chain eliminator to carry out a chain elimination reaction.

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

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

[0047] After the chain elimination reaction is completed, hydrochloric acid aqueous solution is added to terminate the reaction, the organic phase is extracted and separated, and then the solvent is removed by distillation to obtain 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 this invention can improve the selectivity of long-chain linear α-olefins with C8 or more in the product, and the obtained long-chain linear α-olefins are C8 to C98. 30 Linear α-olefins, C 12 ~C 20 The selectivity for linear α-olefins is greater than or equal to 40 mol%, and can even reach 85 mol%.

[0050] In the method of this invention, the ethylene oligomerization activity is as high as 1.44 × 10⁻⁶. 7 g / (mol Fe h), while also having high selectivity, with α-olefin selectivity >98mol% and linear selectivity 100mol%. The oligomers have a narrow distribution, and the product distribution does not follow the Schulz-Flory distribution but rather the Poisson distribution, thus resulting in higher yields of long-chain linear α-olefins.

[0051] Meanwhile, the oligomer does not generate high molecular weight polymers, which can avoid blockages and complex product separation processes in industrial production. In addition, 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 will be further described below with reference to specific embodiments. These embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or according to the manufacturer's recommendations; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0053] To clearly and concisely describe the compounds and coordination compounds in the examples, the following description is provided:

[0054]

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

[0056] Fe2 has the structure of formula I, and R1 is an ethyl group.

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

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

[0059] I. Preparation of bisimine pyridine iron complex

[0060] The bisimine pyridine iron complexes Fe1, Fe2, and Fe3 were synthesized according to the method reported in the Journal of Molecular Catalysis A: Chemical 2002, 179, 155. The synthesis of the bisimine pyridine iron complex Fe4 was performed following the same method as described for Fe1, with 2,6-di-tert-butylaniline 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 was synthesized according to the method reported in Journal of Molecular Catalysis A: Chemical 2002, 179, 155.

[0064] Fe4 synthesis: 1.50 g (9.2 mmol) of 2,6-diacetylpyridine, 3.94 g (19.2 mmol) of 2,6-di-tert-butylaniline, 80 mL of toluene, and a catalytic amount of p-toluenesulfonic acid were added to a side-necked flask, and the mixture was refluxed overnight. After cooling to room temperature, toluene was removed by rotary evaporation, and the ligand was recrystallized from ethanol to obtain the ligand. 1.01 g (1.89 mmol) of the ligand and 0.24 g (1.89 mmol) of FeCl2 were weighed and transferred to a Schlenk flask under nitrogen atmosphere through a three-way tube. 40 mL of anhydrous tetrahydrofuran was added to the side-necked flask, and the mixture was stirred at room temperature for 12 h. The reaction solution was concentrated, and the product solution was filtered, washed three times with anhydrous diethyl ether, and dried to give 0.93 g of a deep blue solid, with a yield of 75%. Elemental analysis (C) 37 H 51 Cl2N3Fe (%) Theoretical values: C, 66.87; H, 7.74; N, 6.32. Measured values: C, 66.61; H, 7.65; N, 6.16. ESI-MS (m / z): 663.58 [M] + .

[0065] II. Selective oligomerization of ethylene to prepare linear α-olefins

[0066] In the following examples, the oligomerization activity was calculated using the final mass of the α-olefin, the amount of metallic iron catalyst, and the polymerization time (activity = mass of α-olefin / (molar amount of metallic iron catalyst × time)); the carbon number distribution of the prepared linear α-olefin was determined by gas chromatography; the α-olefin selectivity was calculated by 1H NMR and gas chromatography; and the linear selectivity was calculated by 1H NMR.

[0067] Examples 1-26 below provide a method for the selective oligomerization of ethylene with an iron catalyst to prepare long-chain linear α-olefins. The specific reaction steps are as follows:

[0068] The autoclave was heated to 150°C and dried under vacuum for 2 hours. Then, the autoclave was slowly cooled to room temperature. After purging the autoclave twice with ethylene, a positive pressure was maintained. 50 mL of toluene solvent, a certain amount of co-catalyst, a certain amount of chain transfer agent, and a certain amount of bisimine pyridine iron catalyst were added to the autoclave. After equilibration to the set temperature, ethylene was introduced at a certain pressure, and the ethylene chain transfer oligomerization reaction was carried out at a certain temperature for 30 minutes. After the oligomerization reaction reached the set time, the ethylene supply was stopped, and the ethylene pressure was adjusted to the chain elimination reaction pressure. 2 mL of tetrahydrofuran (an active species for terminating iron polymerization) and a certain amount of chain eliminator were added to the autoclave, and the chain elimination reaction was carried out at a certain ethylene pressure and temperature for 2 hours. After the chain elimination reaction reached the set time, the ethylene supply was stopped, the pressure was slowly released, the autoclave was opened, and the reaction system was terminated with a 5% hydrochloric acid aqueous solution. The mixture was washed with water, separated, and the organic phase was collected, dried, distilled, and purified by column chromatography to obtain the linear α-olefin product.

[0069] Example 1:

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

[0071] Example 2:

[0072] ① Fe2+ 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℃, time 30 minutes. ② Chain elimination conditions: chain eliminator nickel acetylacetonate, Ni / Fe = 50:1, ethylene pressure 4 atm, temperature 50℃, time 2 hours.

[0073] Example 3:

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

[0075] Example 4:

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

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

[0078] Example 5:

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

[0080] Figure 4 The image shows the carbon NMR spectrum of the linear α-olefin prepared in Example 5, which was then subjected to a chain elimination reaction to obtain the linear α-olefin.

[0081] Example 6:

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

[0083] Example 7:

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

[0085] Example 8:

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

[0087] Example 9:

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

[0089] Example 10:

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

[0091] Example 11:

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

[0093] Example 12:

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

[0095] Example 13:

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

[0097] Example 14:

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

[0099] Example 15:

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

[0101] Example 16:

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

[0103] Example 17:

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

[0105] Example 18:

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

[0107] Example 19:

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

[0109] Example 20:

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

[0111] Example 21:

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

[0113] Example 22:

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

[0115] Example 23:

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

[0117] Example 24:

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

[0119] Example 25:

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

[0121] Example 26:

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

[0123] Comparative Example 1

[0124] No chain transfer agent was used; all other conditions were the same as in Example 3. ① Fe3+ catalyst 1 μmol, co-catalyst MAO, Al / Fe molar ratio = 500:1, ethylene pressure 5 atm, temperature 70℃, time 30 minutes. ② Chain elimination conditions: chain eliminator nickel acetylacetone, Ni / Fe molar ratio = 50:1, ethylene pressure 4 atm, temperature 50℃, time 2 hours. The products were all high molecular weight solid polymers, and no selective oligomerization of ethylene occurred.

[0125] Comparative Example 2

[0126] No chain eliminator was used; otherwise, the process was the same as in Example 3. The catalyst was 1 μmol of Fe3+, the co-catalyst was MAO, the Al / Fe molar ratio was 500:1, the chain transfer agent was ZnEt2, the Zn / Fe molar ratio was 750:1, the ethylene pressure was 5 atm, the temperature was 70°C, and the time was 30 minutes. All polymerization products were saturated alkane products; no olefin products were formed.

[0127]

[0128]

[0129]

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

[0131] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope 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, Includes the following steps: Step 1: Ethylene undergoes oligomerization under the action of a main catalyst, a co-catalyst, and a chain transfer agent; Step 2: After the oligomerization reaction in step 1 is completed, the reaction mixture is mixed with a chain eliminator to carry out a chain elimination reaction, and then the chain elimination reaction is terminated to obtain a long-chain linear α-olefin. The chain transfer agent is diethylzinc and / or diethylmagnesium.

2. The process for the selective oligomerization of ethylene to produce long chain linear alpha-olefins according to claim 1, characterized in that, The main catalyst is a bisimine pyridine iron complex; the co-catalyst is methylaluminoxane or modified methylaluminoxane.

3. The process for the selective oligomerization of ethylene to long chain linear alpha-olefins according to claim 2, characterized in that, The main catalyst has a structure of formula I: R1 is an alkyl group with 1-10 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 500~1000:

1.

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

1.

6. The process for the selective oligomerization of ethylene to produce long chain linear alpha-olefins according to claim 1, characterized in that, In step 1, the pressure of ethylene is 1~50 atm, the temperature of the oligomerization reaction is 10~100℃, and the time is 10min-60min.

7. The process for the selective oligomerization of ethylene to produce long chain linear alpha-olefins according to claim 1, characterized in that, The chain eliminator is at least one of nickel acetylacetonate and nickel bipyridine, and the molar ratio of the chain eliminator to the main catalyst is 20~200:

1.

8. The process for the selective oligomerization of ethylene to produce long chain linear alpha-olefins according to claim 1, characterized in that, The chain elimination reaction is carried out at a temperature of 10~100℃, 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, The chain elimination reaction is terminated by adding hydrochloric acid to acidify the ethanol, wherein the mass fraction of hydrochloric acid in the hydrochloric acid-acidified ethanol is 5-15%.

10. Long chain linear alpha-olefins obtainable by the process according to any one of claims 1 to 9, characterized in that, The long-chain linear α-olefin is C8~C6. 30 Linear α-olefins, C 12 ~C 20 The selectivity for linear α-olefins is greater than or equal to 40 mol.

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