Search

CN-122011046-A - Iron complex, preparation method and application thereof, ethylene oligomerization catalyst and ethylene oligomerization method

CN122011046ACN 122011046 ACN122011046 ACN 122011046ACN-122011046-A

Abstract

The invention provides an iron complex, which has a structural general formula shown in a formula (I), wherein R 1 -R 11 is independently selected from hydrogen, C 1 -C 6 alkyl, halogen, C 1 -C 6 alkoxy, nitro and aryl, R 12 -R 13 are the same or different, each is independently selected from C 3 -C 7 alkenyl, and X is halogen. The iron complex with a specific structure provided by the invention is suitable for being used as a main catalyst of an ethylene oligomerization catalyst. The ethylene oligomerization catalyst using the iron complex as a main catalyst has higher oligomerization activity at a higher temperature (above 60 ℃), the oligomerization activity firstly rises from low to high to about 60 ℃, the catalytic activity drops slowly, the oligomerization reaction is initiated rapidly, the operation is stable and the repeatability is good, and condensed water can be used as a condensing medium for the reaction at the temperature above 60 ℃, so that the energy consumption of a process device is reduced. The invention also provides a preparation method and application of the iron complex, an ethylene oligomerization catalyst and an ethylene oligomerization method.

Inventors

  • LIU JUN
  • ZHENG MINGFANG
  • XU KE
  • WANG HUAIJIE
  • ZHANG HAIYING
  • WU HONGFEI
  • YANG HUAIJUN

Assignees

  • 中国石油化工股份有限公司
  • 中石化(北京)化工研究院有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (12)

  1. 1. An iron complex is characterized in that the structural general formula is shown in the formula (I), In the formula (I), R 1 -R 11 are the same or different and are each independently selected from hydrogen, C 1 -C 6 alkyl, halogen, C 1 -C 6 alkoxy, nitro and aryl, X is halogen, preferably fluorine, chlorine or bromine, R 12 -R 13 are the same or different and are each independently selected from C 3 -C 7 alkenyl; Preferably, in formula (I), each R 1 -R 11 is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluoro, chloro, bromo, methoxy, ethoxy, and nitro; preferably, in formula (I), each R 12 -R 13 is independently selected from C 4 -C 6 alkenyl; Preferably, R 1 -R 7 is hydrogen, and/or R 8 -R 10 is hydrogen, and/or R 11 is hydrogen, methyl or ethyl.
  2. 2. The iron complex according to claim 1, wherein the structural formula is represented by the formula (I-a),
  3. 3. A preparation method of an iron complex is characterized by comprising the following steps of reacting a ligand shown in a formula (II) with ferrous halide in a first organic solvent under the atmosphere of dry inert gas, filtering to obtain the iron complex shown in the formula (I), R 1 -R 11 in the formulae (I) and (II) are identical or different and are each independently selected from the group consisting of hydrogen, C 1 -C 6 alkyl, halogen, C 1 -C 6 alkoxy, nitro and aryl, R 12 -R 13 are identical or different and are each independently selected from the group consisting of C 3 -C 7 alkenyl, in the formula (I), X is halogen, preferably fluorine, chlorine or bromine; Preferably, in formulas (I) and (II), R 1 -R 11 is each independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluoro, chloro, bromo, methoxy, ethoxy, and nitro, preferably R 1 -R 7 is hydrogen, and/or R 8 -R 10 is hydrogen, and/or R 11 is hydrogen, methyl, or ethyl; Preferably, in formulas (I) and (II), R 12 -R 13 is each independently selected from C 4 -C 6 alkenyl; Preferably, the molar ratio of the ligand shown in the formula (II) to the 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 tertiary butyl ether; Preferably, the reaction conditions include a temperature of 20-40 ℃ and stirring for 9-24 hours; preferably, the method for preparing the iron complex further comprises washing the obtained solid with a second organic solvent after filtration, preferably at least one selected from diethyl ether, tetrahydrofuran and methyl tert-butyl ether.
  4. 4. Use of the iron complex of claim 1 or 2 or the iron complex produced by the production process of claim 3 as a main catalyst for an ethylene oligomerization catalyst, preferably comprising a cocatalyst, water and a third organic solvent.
  5. 5. The ethylene oligomerization catalyst is characterized by comprising a main catalyst, a cocatalyst, water and a third organic solvent, wherein the main catalyst is an iron complex shown in a formula (I), In the formula (I), R 1 -R 11 are the same or different and are each independently selected from hydrogen, C 1 -C 6 alkyl, halogen, C 1 -C 6 alkoxy, nitro and aryl, R 12 -R 13 are the same or different and are each independently selected from C 3 -C 7 alkenyl, X is halogen, preferably fluorine, chlorine or bromine; Preferably, in formula (I), R 1 -R 11 is each independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluoro, chloro, bromo, methoxy, ethoxy, and nitro, preferably R 1 -R 7 is hydrogen, and/or R 8 -R 10 is hydrogen, and/or R 11 is hydrogen, methyl, or ethyl; Preferably, in formula (I), each R 12 -R 13 is independently selected from C 4 -C 6 alkenyl.
  6. 6. The catalyst according to claim 5, wherein the main catalyst is an iron complex represented by the formula (I-a),
  7. 7. The use according to claim 4 or the catalyst according to claim 5 or 6, wherein the molar ratio of water to aluminium in the cocatalyst is 0.7-1.5:1, preferably 0.9-1.2:1, and/or, In the catalyst, the content of the main catalyst is 2-500 mu mol/L, preferably 20-100 mu mol/L, based on the volume of the third organic solvent.
  8. 8. The use according to claim 4 or the catalyst according to any one of claims 5-7, the third organic solvent being 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. 9. The use according to claim 4 or the catalyst according to any one of claims 5 to 8, characterized in that the aluminium-containing cocatalyst is selected from at least one of aluminoxane compounds and alkylaluminium compounds, preferably of the general formula AlR n X m , wherein R is each independently a linear or branched C 1 -C 8 alkyl, X is each independently 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 is equal to 3.
  10. 10. Use or catalyst according to claim 9, characterized in that the alkyl aluminium compound is selected from at least one of trimethylaluminium, triethylaluminium, tripropylaluminium, triisobutylaluminium, tri-n-hexylaluminium, tri-n-octylaluminium, diethylaluminium chloride and ethylaluminium dichloride, preferably triethylaluminium.
  11. 11. The use according to claim 4 or the catalyst according to any one of claims 5 to 9, wherein the molar ratio of aluminium in the cocatalyst to iron in the procatalyst is from 30 to less than 900:1, preferably from 100 to 700:1, more preferably from 130 to 220:1, even more preferably from 148 to 196:1.
  12. 12. A process for the oligomerization of ethylene, characterized in that it comprises a catalyst according to any of claims 5-11, preferably comprising the steps of: The preparation method comprises the steps of (1) displacing a reaction system to ensure no water and oxygen in the reaction system, (2) displacing the reaction system by using ethylene to enable the reaction system to be in an ethylene environment, (3) adding a main catalyst, a cocatalyst, water and a third organic solvent into the reaction system, fully stirring, and (4) introducing ethylene to start oligomerization reaction; More preferably, the oligomerization conditions comprise a reaction pressure of 0.1-30 MPa, a reaction temperature of-20-150 ℃, preferably 30-90 ℃, more preferably 60-90 ℃ and a reaction time of 30-100 min; More preferably, in the step (3), the main catalyst and the cocatalyst are dissolved in the third organic solvent and water before being added into the reaction system; more preferably, the ethylene oligomerization product comprises C 4 、C 6 、C 8 、C 10 、C 12 、C 14 、C 16 、C 18 、C 20 、C 22 olefins.

Description

Iron complex, preparation method and application thereof, ethylene oligomerization catalyst and ethylene oligomerization method Technical Field The invention relates to the field of ethylene oligomerization, in particular to an iron complex, a preparation method and application thereof, an ethylene oligomerization catalyst and an ethylene oligomerization method, wherein the ethylene oligomerization catalyst still maintains high catalytic activity at a higher reaction temperature. Background The linear alpha-olefin has wide application in the fields of ethylene comonomer, surfactant synthetic intermediate, alcohol for plasticizer, synthetic lubricating oil, oil additives and the like. In recent years, with the continued development of the polyolefin industry, the worldwide demand for α -olefins has grown rapidly. The vast majority of alpha-olefins are currently produced by ethylene oligomerization. Catalysts used in the ethylene oligomerization process are mainly nickel-based, chromium-based, zirconium-based, aluminum-based, etc., and in recent years, the Brookhart group (Brookhart, M et al, J.am.chem.Soc.,1998,120,7143-7144; WO99/02472,1999), the Gibson group (Gibson, V.C.et al, chem.Commun.,1998,849-850; chem.Eur.J.,2000, 2221-2231) have found that tridentate pyridine imine complexes of Fe (II) and Co (II), respectively, catalyze ethylene oligomerization, and that these catalysts are not only catalytically active but also highly selective for alpha-olefins. The institute of chemical science Sun Wenhua reports a catalyst for oligomerization of ethylene (Organometallics 2006,25,666-677), which is 2-acetyl-1, 10-phenanthroline-2, 6-diethylaniline iron (II) chloride, under the action of methylaluminoxane as a cocatalyst, when the molar ratio of metal aluminum in the cocatalyst to central metal in the main catalyst is 200-2000 and the reaction temperature is 30-60 ℃, oligomerization and polymerization activities are increased and then decreased (see Organometallics 2006,25,666-677, first paragraph of 671), the oligomerization and polymerization activities at 40 ℃ reach up to 4.9x107 g.mol (Fe) -1·h-1, and the problem that the cost is too high and the dosage is too large as a cocatalyst when the cocatalyst is applied to oligomerization of ethylene on a large scale exists. Meanwhile, at the reaction temperature below 40 ℃, chilled water is generally required to be used as a reaction condensing medium, a refrigerating unit is required to be provided for refrigeration, and the process energy consumption is increased. In view of the above, the existing butene oligomerization system has a disadvantage, so that development of a more suitable catalyst system is needed to reduce the cost and energy consumption of ethylene oligomerization. Disclosure of Invention Aiming at the problems in the prior art, the invention aims to provide an iron complex, which is used as an ethylene oligomerization catalyst of a main catalyst and has higher oligomerization activity at a higher temperature (more than 60 ℃), so that condensed water (generally 0-35 ℃) is used as a condensation medium for reaction when the catalyst is used for catalysis at the temperature of more than 60 ℃, chilled water (generally-40-0 ℃) is not needed as the reaction condensation medium, and the aim of reducing the energy consumption of a process device for ethylene oligomerization is fulfilled. Therefore, in a first aspect, the invention provides an iron complex, the structural general formula of which is shown as the formula (I), In the formula (I), R 1-R11 are the same or different and are each independently selected from hydrogen, C 1-C6 alkyl, halogen, C 1-C6 alkoxy, nitro and aryl, X is halogen, preferably fluorine, chlorine or bromine, and R 12-R13 are the same or different and are each independently selected from C 3-C7 alkenyl. The iron complex with a specific structure provided by the invention is suitable for being used as a main catalyst of an ethylene oligomerization catalyst. The ethylene oligomerization catalyst using the iron complex as a main catalyst has higher oligomerization activity at a higher temperature (above 60 ℃), the oligomerization activity firstly rises from low to high to about 60 ℃, the catalytic activity drops slowly, the oligomerization reaction is initiated rapidly, the operation is stable and the repeatability is good, and condensed water can be used as a condensing medium for the reaction at the temperature above 60 ℃, so that the energy consumption of a process device is reduced. As a specific embodiment of the present invention, in formula (I), each R 1-R11 is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluoro, chloro, bromo, methoxy, ethoxy, and nitro. As a specific embodiment of the present invention, in formula (I), each R 12-R13 is independently selected from C 4-C6 alkenyl. As a specific embodiment of the present invention, in formula (I), R 1-R7 is hydrogen. As a specific embodiment of t