Highly selective ethylene tetramerization cr(iii) metal catalyst system and method of use thereof
By improving the ethylene tetramerization Cr(III) metal catalyst system, and utilizing chromium compounds, PXP ligands, and activators, the problem of low 1-octene selectivity in the ethylene oligomerization reaction of existing catalysts was solved, and a highly selective and highly active ethylene tetramerization reaction was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI ZHIXINRUI PETROCHEMICAL TECHNOLOGY CO LTD
- Filing Date
- 2023-12-20
- Publication Date
- 2026-07-03
AI Technical Summary
Existing catalysts exhibit low selectivity for 1-octene and high content of heavy components in ethylene oligomerization, limiting the large-scale application of 1-octene, especially since there are no successful industrial-scale cases in China.
A highly selective ethylene tetramer Cr(III) metal catalyst system, including chromium compounds, PXP ligands, and activators or co-catalysts, is used to improve the selectivity of 1-octene and reduce the content of heavy components through specific ligand structures and solvent combinations.
It improved the selectivity of 1-octene, reduced waxy products, maintained high catalytic activity, and optimized the ethylene tetramerization reaction.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of catalysis technology, specifically to a highly selective ethylene tetramer Cr(III) metal catalyst system and its application method. Background Technology
[0002] Linear α-olefins have a wide range of applications. They can be used chemically as comonomers of plasticizer alcohols and ethylene, and can also be used to produce surfactant synthesis intermediates, plasticizers, etc.
[0003] 1-Hexene obtained via ethylene trimerization is relatively reliable in terms of purity and yield. European patent EP 0417477 reports an ethylene trimerization catalytic system composed of 2,5-dimethylpyrrole, chromium 2-ethylhexanoate, triethylaluminum, and diethylaluminum chloride, and successfully achieved industrial-scale production of 1-hexene in Qatar. The synthesis of 1-octene is similar to that of 1-hexene, mainly involving ethylene oligomerization, ethylene tetramerization, and Fischer-Tropsch synthesis. Ethylene tetramerization is more advanced, and only Sasol has achieved industrial-scale production globally. Currently, most 1-octene is obtained through ethylene oligomerization or extraction separation processes. Oligomerization, however, has low selectivity, with a mass fraction of only 10-20%, high ethylene consumption, and low yield, limiting its widespread application. In 2013, Sasol built the world's first commercial ethylene tetramerization plant in the United States, designed to produce over 100,000 tons of 1-octene and 1-hexene annually. Sasol's selective tetramerization technology for producing 1-octene is an emerging technology specifically designed for 1-octene production. It employs a catalytic system consisting of Cr-based metal compounds, PNP-type ligands, and MAO co-catalysts, achieving a 1-octene selectivity approaching 70%. While existing catalysts and applications can produce C4, C6, and C8 components such as 1-butene, 1-hexene, and 1-octene, their effectiveness in ethylene oligomerization is still not ideal, especially for 1-octene. There are currently no successful industrial-scale examples of 1-octene production in China. Therefore, finding a catalyst with ideal polymerization performance is a pressing issue that needs to be addressed. Summary of the Invention
[0004] To address the aforementioned problems, the present invention aims to provide a highly selective ethylene tetramer Cr(III) metal catalyst system and its method of use. This catalyst system can improve the selectivity of 1-octene, reduce the content of heavy components, and maintain high catalytic activity.
[0005] To achieve the above objectives, this invention discloses a highly selective ethylene tetramerization Cr(III) metal catalyst system, the catalyst system comprising:
[0006] (i) Chromium compounds;
[0007] (ii) Ligands, whose general structural formula is: (Ph2)PXP(Ph2),
[0008] Where the X group is , , , , , One of them.
[0009] (iii) Activator or co-catalyst.
[0010] Preferably, the chromium compound is one of the following: an organic salt, an inorganic salt, a coordination complex, or an organometallic complex of trivalent chromium;
[0011] Preferably, the chromium compound is one of Cr(acac)3, CrCl3(THF)3, chromium(III) 2-ethylhexanoate, and chromium(III) octoate;
[0012] The ligand is a PXP ligand, with the following structure:
[0013] ;
[0014] Preferably, the ligand with high selectivity for the tetramerization of ethylene to 1-octene has one of the following structures:
[0015]
[0016] Ligand 1, Ligand 2, Ligand 3
[0017]
[0018] Ligand 4, ligand 5, ligand 6;
[0019] Preferably, the activator or co-catalyst is one or more of trimethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum dichloride, methylaluminoxane, and modified methylaluminoxane.
[0020] Preferably, the catalyst system further includes a solvent.
[0021] Preferably, the solvent is one of aromatic hydrocarbons, straight-chain or cyclic aliphatic hydrocarbons, or ethers.
[0022] Preferably, the solvent is a cyclic aliphatic hydrocarbon.
[0023] Preferably, the solvent is one of benzene, toluene, ethylbenzene, cumene, xylene, hexane, octane, cyclohexane, methylcyclopentane, hexene, hepten, diethyl ether, and tetrahydrofuran.
[0024] Preferably, the chromium concentration in the catalyst system is 0.01~100 mmol / L.
[0025] Preferably, the chromium concentration in the catalyst system is 10~50 mmol / L.
[0026] Preferably, the molar ratio of the ligand to chromium is 0.01 to 100.
[0027] Preferably, the molar ratio of the ligand to chromium is 1.0 to 3.0.
[0028] Preferably, the molar ratio of the activator or co-catalyst to chromium is 1 to 5000.
[0029] Preferably, the molar ratio of the activator or co-catalyst to chromium is 100 to 1000.
[0030] Preferably, the ligand is prepared as follows: At 0°C, dichlorodiphenylphosphine and the corresponding reactant are added to dichloromethane at a molar ratio of 2:1 and stirred for 40 min. Then, the mixture is stirred at room temperature for 12 h. After stirring, the mixture is filtered and recrystallized to obtain the ligand. Filtration is performed to remove hydrochloride or amine hydrochloride generated during the reaction.
[0031] This invention also discloses a method for using the above-mentioned highly selective ethylene tetramerization Cr(III) metal catalyst system to catalyze ethylene tetramerization, comprising the following steps:
[0032] (1) First, the high-pressure reactor is purged with nitrogen, then purged with ethylene gas; then the solvent is injected into the high-pressure reactor, stirred in an ethylene gas atmosphere, and heated to a certain temperature;
[0033] (2) Inject the activator or co-catalyst, ligand and chromium compound into the high-pressure reactor, stir, introduce ethylene gas into the high-pressure reactor and adjust the pressure inside the reactor to a certain value, and the reaction begins;
[0034] (3) After the reaction has been going on for a period of time, the flow of ethylene gas is shut off and the reaction system is rapidly cooled to 25°C. The reaction product is then treated with a deionized water phase to obtain an organic phase of 1-octene.
[0035] Preferably, in step (1), the temperature is heated to 10~200℃;
[0036] Preferably, in step (1), the temperature is heated to 30~100℃;
[0037] Preferably, in step (2), the pressure inside the vessel is adjusted to 0.6~4 MPa;
[0038] Preferably, the reaction time in step (3) is 10 min to 10 h;
[0039] Preferably, the reaction time in step (3) is 0.5h to 2h;
[0040] Compared with the prior art, the present invention has the following beneficial effects:
[0041] The present invention provides an ethylene tetramer Cr(III) metal catalyst system and its usage method. This catalyst system improves the original PNP chromium-based catalyst, increases the selectivity of 1-octene, reduces waxy products, and maintains high activity. Detailed Implementation
[0042] To better understand the content of this invention, specific embodiments will be used to further illustrate the invention below. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps; however, the scope of protection of this invention is not limited to the following embodiments.
[0043] Example 1:
[0044] (1) Preparation of ligand 1
[0045] At 0 °C, 20 mmol of dichlorodiphenylphosphine and 10 mmol of γ-thiam were added to 50 mL of dichloromethane and stirred for 40 min, then stirred at room temperature for 12 h. After stirring, the mixture was filtered and recrystallized to obtain ligand 1 with a yield of 73%.
[0046] The molar ratio of diphenylphosphine chloride to γ-thiam is 2:1; filtration is to remove the hydrochloride salt produced in the reaction.
[0047] (2) Ethylene tetramerization
[0048] The tetramerization of ethylene was carried out in a 100 mL high-pressure reactor. Before the reaction started, the high-pressure reactor was purged with nitrogen three times, then purged with ethylene twice. Then, 40 mL of cyclohexane solvent was added to the high-pressure reactor, stirred under an ethylene atmosphere, and heated to 50 °C.
[0049] 0.6 mmol of methylaluminoxane (MAO), 6.0 μmol of ligand 1, and 2.0 μmol of CrCl3(THF)3 were added to a high-pressure reactor and stirred for 1 min. Ethylene was then introduced into the reactor, and the pressure was adjusted to 3.0 MPa to initiate the reaction. After 30 min of reaction, the ethylene gas flow was stopped, and the reaction system was rapidly cooled to 25 °C. The reaction product was analyzed using a deionized water phase, followed by organic phase analysis.
[0050] The molar ratio of MAO, ligand 1 and CrCl3(THF)3 is 300:3:1, and the amount of Cr in each reaction is 2.0 μmol.
[0051] The final reaction results are shown in Table 1.
[0052] Example 2:
[0053] (1) Preparation of ligand 2
[0054] At 0 °C, 20 mmol of dichlorodiphenylphosphine and 10 mmol of pyridine were added to 50 mL of dichloromethane and stirred for 40 min, then stirred at room temperature for 12 h. After stirring, the ligand was obtained by filtration and recrystallization with a yield of 75%.
[0055] The molar ratio of diphenyl chlorophosphine to pyridine is 2:1; filtration is to remove the hydrochloride salt produced in the reaction.
[0056] (2) Ethylene tetramerization
[0057] The tetramerization of ethylene was carried out in a 100 mL high-pressure reactor. Before the reaction began, the high-pressure reactor was purged with nitrogen three times and then with ethylene twice to maintain a low water and oxygen level inside the reactor. Then, 40 mL of cyclohexane was added to the high-pressure reactor, stirred under an ethylene atmosphere, and heated to 50 °C.
[0058] 0.6 mmol of MAO, 6.0 μmol of ligand 2, and 2.0 μmol of Cr(acac)3 were added to a high-pressure reactor and stirred for 1 min. Ethylene was then introduced into the reactor, and the pressure inside the reactor was adjusted to 3.0 MPa to initiate the reaction. After 30 min of reaction, the flow of ethylene gas was shut off, and the reaction system was rapidly cooled to 25 °C. The reaction product was analyzed using a deionized water phase, followed by organic phase analysis.
[0059] The molar ratio of MAO, ligand 2 and Cr(acac)3 is 300:3:1, and the amount of Cr in each reaction is 2.0 μmol.
[0060] The final reaction results are shown in Table 1.
[0061] Example 3:
[0062] (1) Preparation of ligand 3
[0063] At 0 °C, 20 mmol of dichlorodiphenylphosphine and 10 mmol of thiophene were added to 50 mL of dichloromethane and stirred for 40 min, then stirred at room temperature for 12 h. After stirring, the mixture was filtered and recrystallized to obtain ligand 3 with a yield of 70%.
[0064] The molar ratio of diphenyl chlorophosphine to thiophene is 2:1; filtration is to remove the hydrochloride produced in the reaction.
[0065] (2) Ethylene tetramerization
[0066] Ethylene tetramerization was carried out in a 100 mL high-pressure reactor. Before the reaction began, the high-pressure reactor was purged with nitrogen three times and then with ethylene twice to maintain a low water and oxygen level inside the reactor. Then, 40 mL of cyclohexane solvent was added to the high-pressure reactor, stirred under an ethylene atmosphere, and heated to 50 °C.
[0067] 0.6 mmol of MAO, 6.0 μmol of ligand 3, and 2.0 μmol of CrCl3(THF)3 were added to a high-pressure reactor and stirred for 1 min. Ethylene was then introduced into the reactor, and the pressure inside the reactor was adjusted to 3.0 MPa to initiate the reaction. After 30 min of reaction, the flow of ethylene gas was shut off, and the reaction system was rapidly cooled to 25 °C. The reaction product was analyzed using a deionized water phase, followed by organic phase analysis.
[0068] The molar ratio of MAO, ligand 3 and CrCl3(THF)3 is 300:3:1, and the amount of Cr in each reaction is 2.0 μmol.
[0069] The final reaction results are shown in Table 1.
[0070] Example 4:
[0071] (1) Preparation of ligand 4
[0072] At 0 °C, 20 mmol of dichlorodiphenylphosphine and 10 mmol of 3H-pyrrole were added to 50 mL of dichloromethane and stirred for 40 min, then stirred at room temperature for 12 h. After stirring, the mixture was filtered and recrystallized to obtain ligand 4 with a yield of 80%.
[0073] The molar ratio of diphenylphosphine chloride to 3H-pyrrole is 2:1; filtration is to remove the hydrochloride salt produced in the reaction.
[0074] (2) Ethylene tetramerization
[0075] Ethylene tetramerization was carried out in a 100 mL high-pressure reactor. Before the reaction began, the high-pressure reactor was purged with nitrogen three times and then with ethylene twice to maintain a low water and oxygen level inside the reactor. Then, 40 mL of cyclohexane solvent was added to the high-pressure reactor, stirred under an ethylene atmosphere, and heated to 50 °C.
[0076] 0.6 mmol of MAO, 6.0 μmol of ligand 4, and 2.0 μmol of Cr(acac)3 were added to a high-pressure reactor and stirred for 1 min. Ethylene was then introduced into the reactor, and the pressure inside the reactor was adjusted to 3.0 MPa to initiate the reaction. After 30 min of reaction, the flow of ethylene gas was shut off, and the reaction system was rapidly cooled to 25 °C. The reaction product was analyzed using a deionized water phase, followed by organic phase analysis.
[0077] The molar ratio of MAO, ligand 4 and Cr(acac)3 is 300:3:1, and the amount of Cr in each reaction is 2.0 μmol.
[0078] The final reaction results are shown in Table 1.
[0079] Example 5:
[0080] (1) Preparation of ligand 5
[0081] At 0 °C, 20 mmol of dichlorodiphenylphosphine and 10 mmol of 9-aminofluorene were added to 50 mL of dichloromethane and stirred for 40 min, then stirred at room temperature for 12 h. After stirring, the mixture was filtered and recrystallized to obtain ligand 5 with a yield of 83%.
[0082] The molar ratio of diphenylphosphine chloride to 9-aminofluorene is 2:1; filtration is to remove the amine hydrochloride produced in the reaction.
[0083] (2) Ethylene tetramerization
[0084] Ethylene tetramerization was carried out in a 100 mL high-pressure reactor. Before the reaction began, the high-pressure reactor was purged with nitrogen three times and then with ethylene twice to maintain a low water and oxygen level inside the reactor. Then, 40 mL of solvent toluene was added to the high-pressure reactor, stirred under an ethylene atmosphere, and heated to 50 °C.
[0085] 0.6 mmol of MAO, 6.0 μmol of ligand 5, and 2.0 μmol of CrCl3(THF)3 were added to a high-pressure reactor and stirred for 1 min. Ethylene was then introduced into the reactor, and the pressure inside the reactor was adjusted to 3.0 MPa to initiate the reaction. After 30 min of reaction, the flow of ethylene gas was shut off, and the reaction system was rapidly cooled to 25 °C. The reaction product was analyzed using a deionized water phase, followed by organic phase analysis.
[0086] The molar ratio of MAO, ligand 5 and CrCl3(THF)3 is 300:3:1, and the amount of Cr in each reaction is 2.0 μmol.
[0087] The final reaction results are shown in Table 1.
[0088] Example 6:
[0089] (1) Preparation of ligand 6
[0090] At 0 °C, 20 mmol of dichlorodiphenylphosphine and 10 mmol of 9,10-dihydroanthracene-9-amine were added to 50 mL of dichloromethane and stirred for 40 min, then stirred at room temperature for 12 h. After stirring, the mixture was filtered and recrystallized to obtain ligand 5 with a yield of 78%.
[0091] The molar ratio of diphenylphosphine chloride to 9,10-dihydroanthracene-9-amine is 2:1; filtration is to remove the amine hydrochloride produced in the reaction.
[0092] (2) Ethylene tetramerization
[0093] Ethylene tetramerization was carried out in a 100 mL high-pressure reactor. Before the reaction began, the high-pressure reactor was purged with nitrogen three times and then with ethylene twice to maintain a low water and oxygen level inside the reactor. Then, 40 mL of solvent toluene was added to the high-pressure reactor, stirred under an ethylene atmosphere, and heated to 50 °C.
[0094] 0.6 mmol of MAO, 6.0 μmol of ligand 6, and 2.0 μmol of CrCl3(THF)3 were added to a high-pressure reactor and stirred for 1 min. Ethylene was then introduced into the reactor, and the pressure inside the reactor was adjusted to 3.0 MPa to initiate the reaction. After 30 min of reaction, the flow of ethylene gas was shut off, and the reaction system was rapidly cooled to 25 °C. The reaction product was analyzed using a deionized water phase, followed by organic phase analysis.
[0095] The molar ratio of MAO, ligand 6 and CrCl3(THF)3 is 300:3:1, and the amount of Cr in each reaction is 2.0 μmol.
[0096] The final reaction results are shown in Table 1.
[0097] Table 1. Effects of different PXP ligands prepared in Examples 1-6 on the selectivity and activity of ethylene tetramerization.
[0098]
[0099] The unit of reaction activity in Table 1, g / (g Cr h), specifically refers to the mass of polymer produced per hour by reacting one gram of chromium catalyst.
[0100] As can be seen from Table 1, different ligands X affect the polymerization effect of the catalyst. Changes in X significantly alter the selectivity and polymerization activity of 1-octene during the polymerization process.
[0101] The highly selective ethylene tetramer Cr(III) metal catalyst system provided by this invention improves the original PNP chromium-based catalyst, increases the selectivity of 1-octene, reduces waxy products, and maintains high activity.
[0102] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A highly selective ethylene tetramerization Cr (III) metal catalyst system characterized by: Includes the following parts: (i) Chromium compounds; (ii) Ligands; (iii) Activator or co-catalyst; The chromium compound is one of the following: an organic salt, an inorganic salt, a coordination complex, or an organometallic complex of trivalent chromium. The structure of the ligand is ; The chromium concentration in the catalyst system is 0.01~100 mmol / L, the molar ratio of the ligand to chromium is 1.0~3.0, and the molar ratio of the activator or co-catalyst to chromium is 100~1000; the activator or co-catalyst is one or more of trimethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum dichloride, and methylaluminoxane.
2. The highly selective ethylene tetramerization Cr(lll) metal catalyst system according to claim 1, characterized in that: The chromium compound is one of Cr(acac)3, CrCl3(THF)3, chromium(III) 2-ethylhexanoate, and chromium(III) octanoate.
3. The highly selective ethylene tetramerization Cr(lll) metal catalyst system according to claim 1, characterized in that: The catalyst system also includes a solvent, which is one of aromatic hydrocarbons, straight-chain or cyclic aliphatic hydrocarbons, or ethers.
4. The highly selective ethylene tetramerization Cr(lll) metal catalyst system according to claim 1, characterized in that: The ligand is prepared as follows: at 0°C, dichlorodiphenylphosphine and the corresponding reactant are added to dichloromethane at a molar ratio of 2:1 and stirred for 40 min. Then, the mixture is stirred at room temperature for 12 h. After stirring, the mixture is filtered and recrystallized to obtain the ligand.
5. A process for the use of a highly selective ethylene tetramerisation Cr (III) metal catalyst system according to any one of claims 1 to 4, characterised in that, Includes the following steps: (1) First, the high-pressure reactor is purged with nitrogen, then purged with ethylene gas; then the solvent is injected into the high-pressure reactor, stirred in an ethylene gas atmosphere, and heated to 10~200℃; (2) Inject the activator or co-catalyst, ligand and chromium compound into the high-pressure reactor, stir, introduce ethylene gas into the high-pressure reactor and adjust the pressure inside the reactor to 0.6~4 MPa, and the reaction begins; (3) After the reaction has been going on for a period of time, the flow of ethylene gas is shut off and the reaction system is rapidly cooled to 25°C. The reaction product is then treated with a deionized water phase to obtain an organic phase of 1-octene.
6. The method of using the highly selective ethylene tetramer Cr(III) metal catalyst system as described in claim 5, characterized in that: The reaction time in step (3) is 10 min to 10 h.
7. The method of using the highly selective ethylene tetramer Cr(III) metal catalyst system as described in claim 5, characterized in that: The solvent is one of benzene, toluene, ethylbenzene, cumene, xylene, hexane, octane, cyclohexane, methylcyclopentane, hexene, hepten, diethyl ether, and tetrahydrofuran.
8. The method of using the highly selective ethylene tetramer Cr(III) metal catalyst system as described in claim 5, characterized in that: In step (1), the temperature is heated to 30~100℃; in step (2), the pressure inside the reactor is adjusted to 0.6~4 MPa; in step (3), the oligomerization reaction time is 0.5h~2h.