Iron complex, preparation method and application thereof, ethylene oligomerization catalyst and ethylene oligomerization method
By combining iron complexes with specific structures, co-catalysts, water, and organic solvents, the problems of reduced activity and high energy consumption of ethylene oligomerization catalysts at high temperatures were solved, achieving a highly efficient ethylene oligomerization reaction and reducing energy consumption and costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-12
AI Technical Summary
Existing ethylene oligomerization catalysts exhibit reduced activity and high energy consumption at high temperatures, while requiring expensive condensation media, resulting in excessively high production costs and energy consumption.
Using a specific iron complex as the main catalyst, combined with a co-catalyst, water, and an organic solvent, and using condensed water as the condensation medium, the catalyst maintains high activity at high temperatures and reduces energy consumption.
Maintaining high oligomerization activity at high temperatures reduces energy consumption in the process unit, achieving a balance between cost and energy consumption, and the catalyst exhibits good operational stability.
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Figure CN122011046A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ethylene oligomerization, specifically to an iron complex and its preparation method and uses, an ethylene oligomerization catalyst, and an ethylene oligomerization method, wherein the ethylene oligomerization catalyst maintains high catalytic activity even at high reaction temperatures. Background Technology
[0002] Linear α-olefins have wide applications in ethylene comonomers, surfactant synthesis intermediates, plasticizer alcohols, synthetic lubricants, and oil additives. In recent years, with the continuous development of the polyolefin industry, the global demand for α-olefins has grown rapidly. Currently, the vast majority of α-olefins are prepared by ethylene oligomerization. The catalysts used in ethylene oligomerization mainly include nickel-based, chromium-based, zirconium-based, and aluminum-based catalysts. In recent years, the Brookhart group (Brookhart, Me et al., J. Am. Chem. Soc., 1998, 120, 7143-7144; WO99 / 02472, 1999) and the Gibson group (Gibson, VC et al., Chem. Commun., 1998, 849-850; Chem. Eur. J., 2000, 2221-2231) have respectively discovered that some Fe(II) and Co(II) tridentate pyridineimine complexes can catalyze ethylene oligomerization. These catalysts not only have high catalytic activity, but also high selectivity for α-olefins.
[0003] The research group of Professor Wenhua Sun at the Institute of Chemistry, Chinese Academy of Sciences, reported a catalyst for ethylene oligomerization (Organometallics 2006, 25, 666-677). This catalyst is ferric(II) chloride-2-acetyl-1,10-phenanthroline condensate-2,6-diethylaniline. With the aid of the co-catalyst methylaluminoxane, when the molar ratio of aluminum in the co-catalyst to the central metal in the main catalyst is 200–2000, and the reaction temperature is 30–60 °C, the oligomerization and polymerization activities first increase and then decrease (see Organometallics 2006, 25, 666-677, page 671, first paragraph). The highest oligomerization and polymerization activities reached 4.9 × 10⁷ g·mol(Fe) at 40 °C. -1 ·h -1 However, both methylaluminoxane and modified methylaluminoxane, when used as cocatalysts, suffer from excessively high costs and require excessive dosages. Their large-scale application as cocatalysts in ethylene oligomerization inevitably leads to high production costs. Furthermore, reaction temperatures below 40°C generally require chilled water as the reaction condensation medium, necessitating refrigeration units and increasing process energy consumption.
[0004] In summary, the current butene oligomerization system still has shortcomings, so there is an urgent need to develop a more suitable catalyst system to reduce the cost and energy consumption of ethylene oligomerization. Summary of the Invention
[0005] To address the aforementioned problems in the prior art, the present invention aims to provide an iron complex as the main catalyst for ethylene oligomerization. This iron complex exhibits high oligomerization activity even at higher temperatures (above 60°C). Therefore, when using this catalyst at temperatures above 60°C, condensed water (generally 0–35°C) can be used as the condensing medium for the reaction, eliminating the need for chilled water (generally -40–0°C) as the condensing medium. This achieves the goal of reducing the energy consumption of the ethylene oligomerization process.
[0006] Therefore, in a first aspect, the present invention provides an iron complex with a general structural formula as shown in formula (I).
[0007]
[0008] In equation (I), R1-R 11 The same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and aryl; X is a halogen, preferably fluorine, chlorine, or bromine; R 12 -R 13 Whether the groups are the same or different, they are each independently selected from C3-C7 alkenyl groups.
[0009] The iron complex with a specific structure provided by this invention is suitable as the main catalyst for ethylene oligomerization. The ethylene oligomerization catalyst using this iron complex as the main catalyst exhibits high oligomerization activity even at higher temperatures (above 60°C). The oligomerization activity initially increases from low to high, but decreases slowly at around 60°C. Furthermore, the oligomerization reaction is rapidly initiated, runs smoothly, and has good repeatability. Moreover, at temperatures above 60°C, condensate can be used as the condensing medium for the reaction, reducing the energy consumption of the process equipment.
[0010] As a specific embodiment of the present invention, in formula (I), R1-R 11 Each is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro.
[0011] As a specific embodiment of the present invention, in formula (I), R 12 -R 13 Each is independently selected from C4-C6 alkenyl groups.
[0012] In a specific embodiment of the present invention, in formula (I), R1-R7 are hydrogen.
[0013] As a specific embodiment of the present invention, in formula (I), R8-R10 It is hydrogen.
[0014] As a specific embodiment of the present invention, in formula (I), R 11 It can be hydrogen, methyl, or ethyl.
[0015] In a specific embodiment of the present invention, in formula (I), R9 is nitro or methoxy; in other embodiments, R9 may also be ethoxy, propoxy, butoxy, or aryl. In further embodiments, nitro, methoxy, ethoxy, propoxy, butoxy, or aryl may also be R1, R2, R3, R4, R5, R6, R7, R8, or R 10 .
[0016] As a specific embodiment of the present invention, the general structural formula of the iron complex is shown in formula (Ia).
[0017]
[0018] In equation (Ia), R1-R 11 They may be the same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro and aryl; X is a halogen, preferably fluorine, chlorine or bromine.
[0019] As a specific embodiment of the present invention, in formula (Ia), R1-R 11 Each is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro.
[0020] In a specific embodiment of the present invention, in formula (Ia), R1-R7 are hydrogen.
[0021] As a specific embodiment of the present invention, in formula (Ia), R8-R 10 It is hydrogen.
[0022] As a specific embodiment of the present invention, in formula (Ia), R 11 It can be hydrogen, methyl, or ethyl.
[0023] As a specific embodiment of the present invention, in formula (Ia) R1-R 11 With equation (I) R1-R 11 same.
[0024] Therefore, in a second aspect, the present invention provides a method for preparing an iron complex, comprising the following steps: reacting a ligand as shown in formula (II) with ferrous halide in a first organic solvent under a dry, inert gas atmosphere, and obtaining an iron complex as shown in formula (I) by filtration.
[0025]
[0026] In equations (I) and (II), R1-R 11 They may be the same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and aryl; R 12 -R 13 They may be the same or different, and each is independently selected from C3-C7 alkenyl groups; in formula (I), X is a halogen, preferably fluorine, chlorine or bromine.
[0027] As a specific embodiment of the present invention, the ferrous halide can be selected from ferrous halide hydrates, such as FeCl2·4H2O.
[0028] In this invention, "dry" means that the water volume content in the reaction system is less than 0.0001%.
[0029] As a specific embodiment of the present invention, in formulas (I) and (II), R1-R 11 Each is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro.
[0030] In a specific embodiment of the present invention, R1-R7 in formulas (I) and (II) are hydrogen.
[0031] As a specific embodiment of the present invention, in formulas (I) and (II), R8-R 10 It is hydrogen.
[0032] As a specific embodiment of the present invention, in formulas (I) and (II), R 11 It can be hydrogen, methyl, or ethyl.
[0033] As a specific embodiment of the present invention, in formulas (I) and (II), R 12 -R 13 Each is independently selected from C4-C6 alkenyl groups.
[0034] As a specific embodiment of the present invention, the molar ratio of the ligand as shown in formula (II) to ferrous halide is 1.0-1.5:1.
[0035] In a specific embodiment of the present invention, the inert gas is nitrogen.
[0036] As a specific embodiment of the present invention, the first organic solvent is selected from at least one of tetrahydrofuran, diethyl ether, and methyl tert-butyl ether.
[0037] As a specific embodiment of the present invention, the reaction conditions include: temperature 20℃-40℃, stirring for 9h-24h.
[0038] As a specific embodiment of the present invention, the method for preparing the iron complex further includes: washing the obtained solid with a second organic solvent after filtration.
[0039] As a specific embodiment of the present invention, the second organic solvent is selected from at least one of diethyl ether, tetrahydrofuran, and methyl tert-butyl ether.
[0040] As a specific embodiment of the present invention, when the iron complex is an iron complex as shown in formula (Ia), its preparation method includes the following steps: under a dry inert gas atmosphere, the ligand as shown in formula (II-a) reacts with ferrous halide in a first organic solvent, and the mixture is filtered to obtain the iron complex as shown in formula (Ia).
[0041]
[0042] In equations (Ia) and (II-a), R1-R 11 They may be the same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro and aryl; in formula (Ia), X is a halogen, preferably fluorine, chlorine or bromine.
[0043] As a specific embodiment of the present invention, in formulas (Ia) and (II-a), R1-R 11 Each is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro.
[0044] In a specific embodiment of the present invention, in formulas (Ia) and (II-a), R1-R7 are hydrogen.
[0045] As a specific embodiment of the present invention, in formulas (Ia) and (II-a), R8-R 10 It is hydrogen.
[0046] As a specific embodiment of the present invention, in formulas (Ia) and (II-a), R 11 It can be hydrogen, methyl, or ethyl.
[0047] As a specific embodiment of the present invention, the molar ratio of the ligand as shown in formula (II-a) to ferrous halide is 1.0-1.5:1.
[0048] As a specific embodiment of the present invention, the preparation method of the iron complex (taking X as Cl as an example) specifically includes the following steps:
[0049]
[0050] In a dry, nitrogen-filled Schlenk reaction tube, the ligand shown in formula (II), FeCl2·4H2O, and tetrahydrofuran were added and stirred at room temperature for 9-24 hours. After the reaction was complete, the mixture was filtered under pressure, and the resulting solid was washed with diethyl ether to obtain the iron complex shown in formula (I).
[0051] Therefore, in a third aspect, the present invention provides the use of the above-described iron complex or the iron complex prepared by the above-described preparation method as a main catalyst for ethylene oligomerization catalysts.
[0052] As a specific embodiment of the present invention, the ethylene oligomerization catalyst further includes a co-catalyst, water, and a third organic solvent.
[0053] When the iron complex provided by this invention is used as the main catalyst for ethylene oligomerization, it combines with the co-catalyst, water, and organic solvent of the ethylene oligomerization catalyst. Through the action of the promoter water, it also has high oligomerization activity at higher temperatures (above 60°C). The oligomerization activity first increases from low to high, and when it reaches about 60°C, the catalytic activity decreases slowly. Moreover, the oligomerization reaction is initiated rapidly, runs smoothly, and has good repeatability. Furthermore, at temperatures above 60°C, condensed water is used as the condensing medium for the reaction, which reduces the energy consumption of the process equipment. This overcomes the technical prejudices of those skilled in the art and achieves unexpected technical effects.
[0054] In a specific embodiment of the present invention, the molar ratio of water to aluminum in the co-catalyst in the ethylene oligomerization catalyst is 0.7–1.5:1. Within this water content range, the catalyst composition exhibits high ethylene oligomerization activity.
[0055] In a specific embodiment of the present invention, the molar ratio of water to aluminum in the co-catalyst in the ethylene oligomerization catalyst is 0.9-1.2:1. Within this water content range, the catalyst composition exhibits higher ethylene oligomerization activity.
[0056] In the catalyst provided by this invention, the amounts of the main catalyst and the co-catalyst can be selected according to the specific process conditions of the application, such as the production scale and production equipment. As a specific embodiment of this invention, preferably, the content of the main catalyst is 2–500 μmol / L (i.e., based on the volume of the third organic solvent) calculated from the volume of the third organic solvent. -6 (mol of main catalyst).
[0057] As a specific embodiment of the present invention, in the ethylene oligomerization catalyst, the content of the main catalyst is 20-100 μmol / L, calculated based on the volume of the third organic solvent.
[0058] In a specific embodiment of the present invention, the third organic solvent is selected from at least one of benzene, toluene, xylene, n-hexane, cyclohexane, n-heptane, methylcyclohexane, diethyl ether, tetrahydrofuran, dioxane, and methyl tert-butyl ether, preferably cyclohexane. The third organic solvent is not selected from halogenated hydrocarbons, such as dichloromethane.
[0059] As a specific embodiment of the present invention, the co-catalyst is selected from at least one of aluminum oxane compounds and alkyl aluminum compounds, preferably alkyl aluminum compounds.
[0060] As a specific embodiment of the present invention, the alkylaluminum compound has the general formula AlR. n X m In each of the following, R is a straight-chain or branched C1-C8 alkyl group; X is a halogen, preferably chlorine or bromine; n is an integer from 1 to 3, m is an integer from 0 to 2, and m+n equals 3.
[0061] As a specific embodiment of the present invention, the alkyl aluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, and ethylaluminum dichloride, preferably triethylaluminum.
[0062] As a specific embodiment of the present invention, the molar ratio of aluminum in the co-catalyst to iron in the main catalyst is 30 to less than 900:1.
[0063] In a specific embodiment of the present invention, the molar ratio of aluminum to iron in the co-catalyst is 100-700:1. Even within this lower molar ratio range, the catalyst exhibits high activity in the ethylene oligomerization reaction.
[0064] In a specific embodiment of the present invention, the molar ratio of aluminum in the co-catalyst to iron in the main catalyst is 130-220:1.
[0065] In a specific embodiment of the present invention, the molar ratio of aluminum in the co-catalyst to iron in the main catalyst is 148-196:1.
[0066] Therefore, in a fourth aspect, the present invention provides an ethylene oligomerization catalyst, comprising: a main catalyst, a co-catalyst, water, and a third organic solvent, wherein the main catalyst is an iron complex of formula (I).
[0067]
[0068] In equation (I), R1-R 11 They may be the same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and aryl; R 12 -R13 Whether the groups are the same or different, they are each independently selected from C3-C7 alkenyl groups; X is a halogen, preferably fluorine, chlorine or bromine.
[0069] The ethylene oligomerization catalyst provided by this invention, through the combination of a specific main catalyst, a co-catalyst, water, and an organic solvent, and through the action of the promoter water, exhibits high oligomerization activity even at higher temperatures (above 60°C). The oligomerization activity initially increases from low to high, and when it reaches around 60°C, the catalytic activity decreases slowly. Furthermore, the oligomerization reaction is initiated rapidly, operates stably, and exhibits good repeatability. Moreover, at temperatures above 60°C, condensed water is used as the condensing medium for the reaction, reducing the energy consumption of the process equipment. This overcomes the technical biases of those skilled in the art and achieves unexpected technical effects.
[0070] The ethylene oligomerization catalyst provided by this invention has high ethylene oligomerization activity and high selectivity for α-olefins.
[0071] As a specific embodiment of the present invention, in formula (I), R1-R 11 Each is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro.
[0072] In a specific embodiment of the present invention, in formula (I), R1-R7 are hydrogen.
[0073] As a specific embodiment of the present invention, in formula (I), R8-R 10 It is hydrogen.
[0074] As a specific embodiment of the present invention, in formula (I), R 11 It can be hydrogen, methyl, or ethyl.
[0075] As a specific embodiment of the present invention, in formula (I), R 12 -R 13 Each is independently selected from C4-C6 alkenyl groups.
[0076] In a specific embodiment of the present invention, the main catalyst is an iron complex represented by formula (Ia).
[0077]
[0078]
[0079] In a specific embodiment of the present invention, the molar ratio of water to aluminum in the co-catalyst is 0.7–1.5:1. Within this water content range, the catalyst composition exhibits high ethylene oligomerization activity.
[0080] In a specific embodiment of the present invention, the molar ratio of water to aluminum in the co-catalyst in the ethylene oligomerization catalyst is 0.9-1.2:1. Within this water content range, the catalyst composition exhibits higher ethylene oligomerization activity.
[0081] In the catalyst provided by this invention, the amounts of the main catalyst and the co-catalyst can be selected according to the specific process conditions of the application, such as the production scale and production equipment. As a specific embodiment of this invention, preferably, the content of the main catalyst is 2–500 μmol / L (i.e., based on the volume of the third organic solvent) calculated from the volume of the third organic solvent. -6 (mol of main catalyst).
[0082] As a specific embodiment of the present invention, the content of the main catalyst is 20-100 μmol / L, calculated based on the volume of the third organic solvent.
[0083] In a specific embodiment of the present invention, the third organic solvent is selected from at least one of benzene, toluene, xylene, n-hexane, cyclohexane, n-heptane, methylcyclohexane, diethyl ether, tetrahydrofuran, dioxane, and methyl tert-butyl ether, preferably cyclohexane. The third organic solvent is not selected from halogenated hydrocarbons, such as dichloromethane.
[0084] As a specific embodiment of the present invention, the molar ratio of aluminum in the co-catalyst to iron in the main catalyst is 30 to less than 900:1.
[0085] In a specific embodiment of the present invention, the molar ratio of aluminum to iron in the co-catalyst is 100-700:1. Even within this lower molar ratio range, the catalyst exhibits high activity in the ethylene oligomerization reaction.
[0086] In a specific embodiment of the present invention, the molar ratio of aluminum to iron in the co-catalyst is 148-196:1. Even within this lower molar ratio range, the catalyst exhibits high activity in the ethylene oligomerization reaction.
[0087] As a specific embodiment of the present invention, the aluminum-containing co-catalyst is selected from at least one of aluminum oxane compounds and alkyl aluminum compounds, preferably alkyl aluminum compounds.
[0088] As a specific embodiment of the present invention, the alkylaluminum compound has the general formula AlR. n X m In each of the following, R is a straight-chain or branched C1-C8 alkyl group; X is a halogen, preferably chlorine or bromine; n is an integer from 1 to 3, m is an integer from 0 to 2, and m+n equals 3.
[0089] As a specific embodiment of the present invention, the alkyl aluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, and ethylaluminum dichloride, preferably triethylaluminum.
[0090] Therefore, in a fifth aspect, the present invention provides a method for ethylene oligomerization, comprising the catalyst described above.
[0091] As a specific embodiment of the present invention, the ethylene oligomerization method includes the following steps:
[0092] (1) Replace the reaction system to ensure that there is no water or oxygen in the reaction system; (2) Replace the reaction system with ethylene to make the reaction system in an ethylene environment; (3) Add the main catalyst, co-catalyst, water and third organic solvent to the reaction system and stir thoroughly; (4) Introduce ethylene to start the oligomerization reaction.
[0093] In a specific embodiment of the present invention, after the oligomerization reaction in step (4) is completed, the reaction product is analyzed by gas chromatography (GC). The results show that the oligomerization activity can reach 1-4 × 10⁻⁴. 7 g·mol(Fe) -1 ·h -1 The selectivity for α-olefins can reach over 95%. Furthermore, the remaining reaction mixture was neutralized with an ethanol solution acidified with 5% dilute hydrochloric acid, and no polymer was obtained, indicating that the oligomerization reaction has good selectivity and few side reactions.
[0094] As a specific embodiment of the present invention, the conditions for the oligomerization reaction include: reaction pressure 0.1-30 MPa, reaction temperature -20-150°C, preferably 30-90°C, more preferably 60-90°C, and reaction time 30-100 min.
[0095] Specifically, as the reaction pressure of ethylene increases, the oligomerization activity increases.
[0096] As a specific embodiment of the present invention, in step (3), the main catalyst and the co-catalyst are first dissolved in the third organic solvent and water before being added to the reaction system.
[0097] As a specific embodiment of the present invention, the ethylene oligomerization products include C4, C6, C8, and C6. 10 C 12 C 14 C 16 C 18 C 20 C 22 Olefins.
[0098] Beneficial effects:
[0099] The iron complex with a specific structure provided by this invention is suitable as the main catalyst for ethylene oligomerization. The ethylene oligomerization catalyst using this iron complex as the main catalyst exhibits high oligomerization activity even at higher temperatures (above 60°C). The oligomerization activity initially increases from low to high, but decreases slowly at around 60°C. Furthermore, the oligomerization reaction is rapidly initiated, runs smoothly, and has good repeatability. Moreover, at temperatures above 60°C, condensate can be used as the condensing medium for the reaction, reducing the energy consumption of the process equipment.
[0100] When the iron complex provided by this invention is used as the main catalyst for ethylene oligomerization, it combines with the co-catalyst, water, and organic solvent of the ethylene oligomerization catalyst. Through the action of the promoter water, it also has high oligomerization activity at higher temperatures (above 60°C). The oligomerization activity first increases from low to high, and when it reaches about 60°C, the catalytic activity decreases slowly. Moreover, the oligomerization reaction is initiated rapidly, runs smoothly, and has good repeatability. Furthermore, at temperatures above 60°C, condensed water is used as the condensing medium for the reaction, which reduces the energy consumption of the process equipment. This overcomes the technical prejudices of those skilled in the art and achieves unexpected technical effects.
[0101] The ethylene oligomerization catalyst provided by this invention, through the combination of a specific main catalyst, a co-catalyst, water, and an organic solvent, and through the action of the promoter water, exhibits high oligomerization activity even at higher temperatures (above 60°C). The oligomerization activity initially increases from low to high, and when it reaches around 60°C, the catalytic activity decreases slowly. Furthermore, the oligomerization reaction is initiated rapidly, operates stably, and exhibits good repeatability. Moreover, at temperatures above 60°C, condensed water is used as the condensing medium for the reaction, reducing the energy consumption of the process equipment. This overcomes the technical biases of those skilled in the art and achieves unexpected technical effects.
[0102] The ethylene oligomerization method provided by this invention involves ethylene undergoing oligomerization under the action of a catalyst composition consisting of an iron complex main catalyst, a co-catalyst, water, and an organic solvent, as shown in formula (I). This method exhibits high oligomerization activity even at higher temperatures (above 60°C), and the oligomerization reaction is rapidly initiated, runs smoothly, and has good repeatability. Furthermore, at temperatures above 60°C, condensate is used as the condensing medium for the reaction, requiring a refrigeration unit for cooling, which reduces the energy consumption of the process equipment. This overcomes the technical biases of those skilled in the art and achieves unexpected technical effects.
[0103] The ethylene oligomerization method provided by this invention achieves a good balance between catalytic effect and cost, resulting in a significant reduction in the cost of ethylene oligomerization reaction. It is highly practical and has broad prospects for industrialization. Detailed Implementation
[0104] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0105] In this invention, the term "C1-C6 alkyl" refers to a saturated straight-chain or branched hydrocarbon group containing 1-6 carbon atoms. Examples of C1-C6 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, n-hexyl, and sec-hexyl; methyl, ethyl, n-propyl, and isopropyl are particularly preferred.
[0106] In this invention, the term "C1-C6 alkoxy" refers to a group formed by attaching the aforementioned C1-C6 alkyl group to an oxygen atom. Examples of C1-C6 alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, sec-pentoxy, n-hexoxy, and sec-hexoxy; methoxy and ethoxy are particularly preferred.
[0107] In this invention, the term "halogen" refers to fluorine, chlorine, bromine and iodine, with fluorine, chlorine and bromine being particularly preferred.
[0108] In this invention, the term "straight-chain or branched C1-C8 alkyl" refers to a saturated straight-chain or branched hydrocarbon group containing 1-8 carbon atoms. C1-C8 alkyl groups may include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, n-hexyl, sec-hexyl, n-heptyl, sec-heptyl, n-octyl, and sec-octyl.
[0109] (I) Testing Methods
[0110] The C4 content in the examples and comparative examples was directly determined by gas chromatography.
[0111] The catalyst activity and linear α-olefin content in the examples and comparative examples were calculated using the following formulas.
[0112]
[0113] Preparation Example 1
[0114] Iron complex (III) was prepared by the following steps.
[0115] In a dry (5 ppm water) nitrogen-filled Schlenk reaction tube, ligand (III-1) (0.20 mmol), FeCl2·4H2O (28.4 mg, 0.2 mmol), and tetrahydrofuran (7.0 mL) were added. The mixture was stirred at room temperature for 9 h. After the reaction was complete, the mixture was filtered under pressure. The resulting solid was washed with diethyl ether (10 mL × 3) to obtain iron complex (III). Elemental analysis results of iron complex (III): Molecular formula, C 27 H 25 C l2 FeN3; Molecular weight: 518.26; Theoretical value: C, 62.57; H, 4.86; Cl, 13.68; Fe, 10.78; N, 8.11; Measured value: C, 62.37; H, 4.91; N, 8.06.
[0116]
[0117] Preparation Example 2
[0118] The iron complex (IV) was prepared by the following steps.
[0119] In a dry (5 ppm water) nitrogen-filled Schlenk reaction tube, ligand (IV-1) (0.20 mmol), FeCl₂·4H₂O (28.4 mg, 0.2 mmol), and tetrahydrofuran (7.0 mL) were added. The mixture was stirred at room temperature for 9 h. After the reaction was complete, the mixture was filtered under pressure. The resulting solid was washed with diethyl ether (10 mL × 3) to obtain the iron complex (IV). Elemental analysis results of the iron complex (IV): Molecular formula, C 28 H 27 C l2 FeN3; Molecular weight: 532.29; Theoretical values: C, 63.18; H, 5.11; Cl, 13.32; Fe, 10.49; N, 7.89; Measured values: C, 63.02; H, 5.12; N, 7.91.
[0120]
[0121] Preparation Example 3
[0122] The iron complex (V) was prepared by the following steps.
[0123] In a dry (5 ppm water) nitrogen-filled Schlenk reaction tube, ligand (IV-1) (0.20 mmol), FeBr2 (0.2 mmol), and tetrahydrofuran (7.0 mL) were added. The mixture was stirred at room temperature for 9 h. After the reaction was complete, it was filtered under pressure. The resulting solid was washed with diethyl ether (10 mL × 3) to obtain the iron complex (V). Elemental analysis results of the iron complex (V): Molecular formula, C 28 H 27 Br2FeN3; Molecular weight: 621.20; Theoretical values: C, 54.14; H, 4.38; Br, 25.73; Fe, 8.99; N, 6.76; Measured values: C, 54.12; H, 4.56; N, 6.79.
[0124]
[0125] Preparation Example 4
[0126] The iron complex (VI) was prepared by the following steps.
[0127] In a dry (5 ppm water) nitrogen-filled Schlenk reaction tube, ligand (VI-1) (0.20 mmol), FeCl₂·4H₂O (28.4 mg, 0.2 mmol), and tetrahydrofuran (7.0 mL) were added. The mixture was stirred at room temperature for 9 h. After the reaction was complete, the mixture was filtered under pressure. The resulting solid was washed with diethyl ether (10 mL × 3) to obtain the iron complex (VI). Elemental analysis results of the iron complex (VI): Molecular formula, C 28 H 26 Cl2FeN4O2; Molecular weight: 577.29; Theoretical values: C, 58.26; H, 4.54; Cl, 12.28; Fe, 9.67; N, 9.71; O, 5.54; Measured values: C, 58.20; H, 4.70; N, 9.68.
[0128]
[0129] Preparation Example 5
[0130] Iron complex (VII) was prepared by the following steps.
[0131] In a dry (5 ppm water) nitrogen-filled Schlenk reaction tube, ligand (VII-1) (0.20 mmol), FeCl₂·4H₂O (28.4 mg, 0.2 mmol), and tetrahydrofuran (7.0 mL) were added. The mixture was stirred at room temperature for 9 h. After the reaction was complete, it was filtered under pressure. The resulting solid was washed with diethyl ether (10 mL × 3) to obtain the iron complex (VII). Elemental analysis results of the iron complex (VII): Molecular formula, C29 H 29 Cl2FeN3O; Molecular weight: 556.32; Theoretical values: C, 61.94; H, 5.20; Cl, 12.61; Fe, 9.93; N, 7.47; O, 2.85; Measured values: C, 61.90; H, 5.21; N, 7.41.
[0132]
[0133] Example 1
[0134] The ethylene oligomerization reaction specifically includes the following steps:
[0135] (1) The reaction system is replaced by high-temperature drying, vacuum replacement and other operations to ensure that the reaction system is free of water and oxygen;
[0136] (2) Replace the reaction system with ethylene to make the reaction system be in an ethylene environment;
[0137] (3) Add water and cyclohexane solvent to the reactor, add 1.37 mL of triethylaluminum cyclohexane solution (concentration of 715 μmol / mL), add 2 mL of cyclohexane solution of iron complex of formula (III) (concentration of 2.5 μmol / mL), and make the total volume of the composition 100 mL, wherein H2O / Al (molar ratio) = 1, and the molar ratio of aluminum in the co-catalyst to iron in the main catalyst, i.e. Al / Fe (molar ratio) = 196, and stir thoroughly;
[0138] (4) Introduce ethylene to start the oligomerization reaction, keep the ethylene pressure at 1MPa and the reaction temperature at 60℃, and react for 30 minutes.
[0139] (5) Stop the reaction and take out a small amount of the reaction product for gas chromatography (GC) analysis: the oligomerization activity is 2.32 × 10⁻⁶. 7 g·mol(Fe) -1 ·h -1 The C4 content was 14.9 wt%, of which 97.5 wt% was linear α-olefin. The remaining mixture was neutralized with an ethanol solution acidified with 5 wt% hydrochloric acid, but no polymer was obtained. The analytical results are shown in Table 1.
[0140] Example 2
[0141] Same as Example 1, except that the reaction temperature was 35°C. Data are shown in Table 1.
[0142] Example 3
[0143] Same as Example 1, except that the reaction temperature was 40°C. Data are shown in Table 1.
[0144] Example 4
[0145] Same as Example 1, except that the reaction temperature was 45°C. Data are shown in Table 1.
[0146] Example 5
[0147] Same as Example 1, except that the reaction temperature was 50°C. Data are shown in Table 1.
[0148] Example 6
[0149] Same as Example 1, except that the reaction temperature was 55°C. Data are shown in Table 1.
[0150] Example 7
[0151] Same as Example 1, except that the reaction temperature was 65°C. Data are shown in Table 1.
[0152] Example 8
[0153] Same as Example 1, except that the reaction temperature was 70°C. Data are shown in Table 1.
[0154] Example 9
[0155] Same as Example 1, except that the reaction temperature was 75°C. Data are shown in Table 1.
[0156] Example 10
[0157] Same as Example 1, except that the reaction temperature was 80°C. Data are shown in Table 1.
[0158] Example 11
[0159] Same as Example 1, except that the reaction temperature was 90°C. Data are shown in Table 1.
[0160] Example 12
[0161] Same as Example 1, except that the iron complex of formula (III) is replaced with the iron complex of formula (IV).
[0162] The analysis results are shown in Table 1.
[0163]
[0164] Example 13
[0165] Same as Example 1, except that the iron complex of formula (III) is replaced with the iron complex of formula (V).
[0166] The analysis results are shown in Table 1.
[0167]
[0168] Example 14
[0169] Same as Example 1, except that the complex of formula (III) was replaced with the complex of formula (VI). The analytical results are shown in Table 1.
[0170]
[0171] Example 15
[0172] Same as Example 1, except that the complex of formula (III) was replaced with the complex of formula (VII). The analytical results are shown in Table 1.
[0173]
[0174] Comparative Example 1
[0175] Same as Example 7, except that in step (3), only cyclohexane solvent is added to the reactor, and water is not added. The data are shown in Table 1.
[0176] The ethylene oligomerization reaction specifically includes the following steps:
[0177] (1) The reaction system is replaced by high-temperature drying, vacuum replacement and other operations to ensure that the reaction system is free of water and oxygen;
[0178] (2) Replace the reaction system with ethylene to make the reaction system be in an ethylene environment;
[0179] (3) Add cyclohexane solvent to the reactor, add 1.37 mL of triethylaluminum cyclohexane solution (concentration of 715 μmol / mL), add 2 mL of cyclohexane solution of formula (III) complex (concentration of 2.5 μmol / mL), so that the total volume of the composition is 100 mL, and the molar ratio of aluminum in the co-catalyst to iron in the main catalyst, i.e. Al / Fe (molar ratio) = 196, and stir thoroughly;
[0180] (4) Introduce ethylene to start the oligomerization reaction, keep the ethylene pressure at 1MPa and the reaction temperature at 60℃, and react for 30 minutes.
[0181] (5) Stop the reaction and take out a small amount of the reaction product for gas chromatography (GC) analysis: the oligomerization activity is 1.17 × 10⁻⁶. 4 g·mol(Fe) -1 ·h -1 The C4 content was 14.5 wt%, of which 97.3 wt% was linear α-olefin. The remaining mixture was neutralized with an ethanol solution acidified with 5 wt% hydrochloric acid to obtain the polymer. The analytical results are shown in Table 1.
[0182] Comparative Example 2
[0183] Same as Example 1, except that the complex of formula (III) was replaced with 2-acetyl-1,10-phenanthroline condensate-2,6-diethylaniline iron(II). The analytical results are shown in Table 1.
[0184] Comparative Example 3
[0185] Similar to Comparative Example 2, except that the reaction temperature in step (4) is 50℃. The analytical results are shown in Table 1.
[0186] Comparative Example 4
[0187] Similar to Comparative Example 2, except that the reaction temperature in step (4) is 70℃. The analytical results are shown in Table 1.
[0188] Table 1
[0189]
[0190] As shown in Table 1, under the catalysis of the catalyst provided by the present invention, the ethylene oligomerization reaction in Examples 1-15 also has high oligomerization activity at higher temperatures (above 60°C). The oligomerization activity first increases from low to high, and when it reaches about 60°C, the catalytic activity decreases slowly. Moreover, the oligomerization reaction is initiated rapidly, runs smoothly, and has good repeatability. Furthermore, at temperatures above 60°C, condensate can be used as the condensing medium for the reaction, eliminating the need for a refrigeration unit and reducing the energy consumption of the process equipment.
[0191] Among ethylene oligomers, C4 has the lowest added value. Generally, to increase overall techno-economic efficiency, the content of C4 in oligomers should be minimized, thereby improving overall techno-economic efficiency. Compared with Comparative Example 2, Example 1 shows an increased content of linear α-olefins and a decreased content of C4 in its product; therefore, Example 1 has better economic value.
[0192] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. An iron complex, characterized in that, Its general structural formula is shown in equation (I). In equation (I), R1-R 11 The same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and aryl; X is a halogen, preferably fluorine, chlorine, or bromine; R 12 -R 13 Whether the groups are the same or different, they are each independently selected from C3-C7 alkenyl groups; Preferably, in formula (I), R1-R 11 Each is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro; Preferably, in formula (I), R 12 -R 13 Each is independently selected from C4-C6 alkenyl groups; Preferably, R1-R7 are hydrogen; and / or, R8-R 10 For hydrogen; and / or, R 11 It can be hydrogen, methyl, or ethyl.
2. The iron complex according to claim 1, characterized in that, Its general structural formula is shown in equation (Ia).
3. A method for preparing an iron complex, characterized in that, Includes the following steps: Under a dry, inert gas atmosphere, the ligand shown in formula (II) reacts with ferrous halide in a first organic solvent, and the reaction is filtered to obtain the iron complex shown in formula (I). In equations (I) and (II), R1-R 11 They may be the same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and aryl; R 12 -R 13 They may be the same or different, and each is independently selected from C3-C7 alkenyl groups; in formula (I), X is a halogen, preferably fluorine, chlorine or bromine; Preferably, in formulas (I) and (II), R1-R 11 Each of the following groups is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro; preferably, R1-R7 are hydrogen; and / or, R8-R 10 For hydrogen; and / or, R 11 It can be hydrogen, methyl, or ethyl; Preferably, in formulas (I) and (II), R 12 -R 13 Each is independently selected from C4-C6 alkenyl groups; Preferably, the molar ratio of the ligand as shown in formula (II) to ferrous halide is 1.0-1.5:1; Preferably, the inert gas is nitrogen; Preferably, the first organic solvent is selected from at least one of tetrahydrofuran, diethyl ether, and methyl tert-butyl ether; Preferably, the reaction conditions include: temperature 20℃-40℃, stirring for 9h-24h; Preferably, the method for preparing the iron complex further includes: washing the obtained solid with a second organic solvent after filtration, wherein the second organic solvent is selected from at least one of diethyl ether, tetrahydrofuran, and methyl tert-butyl ether.
4. Use of the iron complex according to claim 1 or 2 or the iron complex prepared by the preparation method according to claim 3 as the main catalyst of an ethylene oligomerization catalyst, preferably, the ethylene oligomerization catalyst further includes a co-catalyst, water and a third organic solvent.
5. An ethylene oligomerization catalyst, characterized in that, include: The composition includes a main catalyst, a co-catalyst, water, and a third organic solvent, wherein the main catalyst is an iron complex of formula (I). In equation (I), R1-R 11 They may be the same or different, each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy, nitro, and aryl; R 12 -R 13 They may be the same or different, and are each independently selected from C3-C7 alkenyl groups; X is a halogen, preferably fluorine, chlorine or bromine; Preferably, in formula (I), R1-R 11 Each of the following groups is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy, and nitro; preferably, R1-R7 are hydrogen; and / or, R8-R 10 For hydrogen; and / or, R 11 It can be hydrogen, methyl, or ethyl; Preferably, in formula (I), R 12 -R 13 Each is independently selected from C4-C6 alkenyl groups.
6. The catalyst according to claim 5, characterized in that, The main catalyst is an iron complex of formula (Ia).
7. The use according to claim 4 or the catalyst according to claim 5 or 6, characterized in that, In the catalyst, the molar ratio of water to aluminum in the co-catalyst is 0.7–1.5:1, preferably 0.9–1.2:1; and / or, In the catalyst, the content of the main catalyst is 2 to 500 μmol / L, preferably 20 to 100 μmol / L, based on the volume of the third organic solvent.
8. The use according to claim 4 or the catalyst according to any one of claims 5-7, wherein the third organic solvent is selected from at least one of benzene, toluene, xylene, n-hexane, cyclohexane, n-heptane, methylcyclohexane, diethyl ether, tetrahydrofuran, dioxane, and methyl tert-butyl ether, preferably cyclohexane.
9. The use according to claim 4 or the catalyst according to any one of claims 5-8, characterized in that, The aluminum-containing cocatalyst is selected from at least one of aluminum oxane compounds and alkyl aluminum compounds, preferably alkyl aluminum compounds; more preferably, the alkyl aluminum compound has the general formula AlR. n X m In each of the following, R is a straight-chain or branched C1-C8 alkyl group; X is a halogen, preferably chlorine or bromine; n is an integer from 1 to 3, m is an integer from 0 to 2, and m+n equals 3.
10. The use or catalyst according to claim 9, characterized in that, The alkylaluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, and ethylaluminum dichloride, preferably triethylaluminum.
11. The use according to claim 4 or the catalyst according to any one of claims 5-9, characterized in that, The molar ratio of aluminum in the co-catalyst to iron in the main catalyst is 30 to less than 900:1, preferably 100-700:1, more preferably 130-220:1, and even more preferably 148-196:
1.
12. A method for ethylene oligomerization, characterized in that, The catalyst included in any one of claims 5-11; preferably, the ethylene oligomerization method includes the following steps: (1) Replace the reaction system to ensure that the reaction system is free of water and oxygen; (2) Replace the reaction system with ethylene to make the reaction system in an ethylene environment; (3) Add the main catalyst, co-catalyst, water and third organic solvent to the reaction system and stir thoroughly; (4) Introduce ethylene to start the oligomerization reaction. More preferably, the conditions for the oligomerization reaction include: reaction pressure 0.1-30 MPa, reaction temperature -20-150°C, preferably 30-90°C, more preferably 60-90°C, and reaction time 30-100 min; More preferably, in step (3), the main catalyst and the co-catalyst are first dissolved in the third organic solvent and water before being added to the reaction system; More preferably, the ethylene oligomers include C4, C6, C8, and C6. 10 C 12 C 14 C 16 C 18 C 20 C 22 Olefins.