Catalyst system for the dimerization of ethylene to 1-butene

Abstract

The application discloses a catalyst system for preparing 1-butene by ethylene dimerization. The catalyst system comprises the following components: a, an organic titanium compound; b, an organic aluminum compound; c, a compound shown in the following formula; the catalyst system has high catalytic activity and can realize high 1-butene selectivity and low PE yield, and can significantly improve device operation; meanwhile, the service life of single batch of catalyst is long, and when applied to actual industrial production, catalyst utilization maximization can be realized by controlling catalyst feed quantity and / or residence time, and economic benefits are improved.

Description

Technical Field

[0001] This invention relates to a catalyst composition, and more particularly to a catalyst system for the preparation of 1-butene from ethylene dimerization. Background Technology

[0002] Among the catalytic systems capable of selectively dimerizing ethylene to synthesize 1-butene, vanadium-based catalytic systems (K. Nomura et al., Inorg. Chem. 2013, 52, 2607), iron or cobalt-based catalytic systems (S. Song et al., J. Organomet. Chem. 2011, 696, 2594), tungsten-based catalytic systems (WO2005089940A2, 2005), tantalum-based catalytic systems (S. McLain et al., J. Am. Chem. Soc., 1978, 100(4), 1315), nickel-based catalytic systems (S. Mukherjee et al., Organometallics. 2009, 28, 3074), or titanium-based catalytic systems (Al-Sa'Doun AW. et al., Applied Catalysis A: General, 1993, 105, 1-40).

[0003] Among these systems, titanium-based catalytic systems are the best to date. In known techniques, a method for dimerizing ethylene to 1-butene using a catalyst obtained by mixing trialkylaluminum with titanium tetraolide or zirconium tetraolide has been described, exhibiting good selectivity. However, this reaction also forms a certain amount of high molecular weight polymer (i.e., polyethylene, PE). The accumulation of polyethylene in the reactor or heat exchanger severely affects the mixing efficiency of the reaction solution and the heat exchange capacity, making scale-up relatively difficult and shortening the cleaning cycle of the reactor and heat exchanger, thus seriously affecting the continuous operation of the plant. Therefore, developing ethylene dimerization catalyst systems with high activity and low polymer selectivity is of great significance.

[0004] In addition, the activity of the currently industrialized ethylene dimerization catalytic system is relatively low. Therefore, extending the service life of the catalyst to reduce production costs is particularly important in practical industrial applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention first proposes a catalyst system for the dimerization of ethylene to prepare 1-butene. This catalyst system comprises organotitanium, organoaluminum, and oxygen-containing heterocyclic compounds. Through the synergistic effect of these components, it not only exhibits high catalytic activity and achieves high 1-butene selectivity but also produces low PE yield, significantly improving equipment operation. Furthermore, the catalyst has a long service life per batch. In practical industrial production, catalyst utilization can be maximized by controlling the catalyst feed rate and / or residence time, thereby improving economic efficiency.

[0006] Secondly, this invention also proposes a method for preparing 1-butene by ethylene dimerization. This method involves carrying out the ethylene polymerization reaction in the presence of a catalyst system used for preparing 1-butene by ethylene dimerization, which is beneficial for preparing products with high selectivity for 1-butene and low PE production.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A catalyst system for the preparation of 1-butene from ethylene dimerization comprises the following components:

[0009] a. Organotitanium compounds;

[0010] b. Organoaluminum compounds;

[0011] c. The compound shown in Formula I;

[0012]

[0013] In Formula I, n is an integer between 1 and 100, preferably an integer between 1 and 25.

[0014] In a preferred embodiment of the present invention, the organotitanium compound is an alkoxytitanium compound and / or an aryloxytitanium compound, preferably an alkoxytitanium compound and / or an aryloxytitanium compound having 1-30 carbon atoms, and more preferably, the organotitanium compound is selected from compounds having the expression shown in Formula II:

[0015] Ti(OR)4 formula II

[0016] Wherein, R is selected from C1-C20 alkyl, C6-C30 aryl or alkylaryl, preferably selected from methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, 2-methylethyl, 2-methylpropyl, pentyl, 2-methylbutyl, 3-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, hexyl, 2-methylpentyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, eicosyl, phenyl, benzyl, p-tolyl, o-tolyl, m-tolyl, 2,6 -Dimethylphenyl, 2,4,6-trimethylphenyl, 4-methylphenyl, 2-phenylphenyl, 2,6-diphenylphenyl, 2,4,6-triphenylphenyl, 4-phenylphenyl, 2-tert-butyl-6-phenylphenyl, 2,4-di-tert-butyl-6-phenylphenyl, 2,6-diisopropylphenyl, 2,6-di-tert-butylphenyl, 4-methyl-2,6-di-tert-butylphenyl, 2,6-dichloro-4-tert-butylphenyl, 2,6-dibromo-4-tert-butylphenyl, biphenyl, binaphthyl, 1,8-dimethylnaphthyl.

[0017] As a preferred embodiment of the present invention, the organoaluminum compound is selected from at least one of alkylaluminum, aluminum oxane, and alkylaluminum chloride, preferably one or more of methylaluminoxane, modified methylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, monochloroethylaluminum, sesquiethylaluminum chloride, and dichloroethylaluminum.

[0018] In a preferred embodiment of the present invention, the amount of the organoaluminum compound relative to the organotitanium compound, in terms of the molar ratio of metallic Al to metallic Ti, is (2-100):1, preferably (2-30):1.

[0019] As a preferred embodiment of the present invention, the molar ratio of metallic Al in the compound shown in Formula I and the organoaluminum compound is (0.01-1):1, preferably (0.02-0.4):1.

[0020] The present invention also provides a method for preparing 1-butene by ethylene dimerization, wherein ethylene polymerization is carried out in the presence of the catalyst system described above; the reaction temperature is 20-150℃, preferably 30-60℃, and the polymerization pressure is 2-5MPa, preferably 2-3.5MPa.

[0021] As a preferred embodiment of the method in this invention, a solvent is added to the ethylene polymerization reaction system, wherein the solvent is selected from one or more of 1-butene, propane, butane, pentane, hexane, methylcyclohexane, heptane, octane, nonane, decane, and Isopar solvent.

[0022] As a preferred embodiment of the method in this invention, the amount of catalyst system added in the polymerization reaction, based on the molar concentration of metallic Ti in the solvent, is 0.2-0.8 mmol / L.

[0023] This invention provides a synergistic catalyst system with high catalytic activity for ethylene dimerization and low PE production, and the catalyst system has an extended service life in single-batch performance testing. Detailed Implementation

[0024] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0025] Unless otherwise specified, all raw materials and reagents used in the following embodiments of the present invention were obtained through commercially available sources. The main raw material information is as follows:

[0026] Industrial hexane, 100% alkane, Jingbo;

[0027] Methylcyclohexane, 99.8%, Hubei Jubang;

[0028] Triethylaluminum hexane solution, 1 mol / L, Inokane

[0029] Ethylene, polymerization grade, produced by Air Liquide;

[0030] 1-Butene, 99%, light source;

[0031] Triisobutylaluminum hexane solution, 1 mol / L, Inokai;

[0032] Sesquiethylaluminum, 1 mol / L, Inokai;

[0033] Tetrabutyl titanate, 99%, Inokai;

[0034] Isopropyl titanate, 98%, Inokai;

[0035] Tetraethyl titanate, 98%, Inokai;

[0036] Preparation of the compound shown in Formula I:

[0037]

[0038] (1) Compound IA (n=1)

[0039] 699g of tetrahydrofurfuryl alcohol and 0.3g of anhydrous zinc chloride catalyst were added to a 3L reactor. The reactor was evacuated to -0.095MPa using a vacuum pump, and then purged with nitrogen to a pressure of 0.050MPa. The pressure was then reduced to -0.095MPa again, and the reactor was heated to 60℃. 301g of ethylene oxide was introduced into the reactor, and the pressure was kept below 0.45MPa during the introduction of ethylene oxide. After the addition of ethylene oxide, the reactor was kept at this temperature for 0.8h for curing. Unreacted ethylene oxide was removed from the reactor using a circulating water vacuum pump. The product was tested by GPC and found to have a molecular weight of approximately 146.18 and a molecular weight distribution of approximately 1.001.

[0040] (2) Compound IB (n=3)

[0041] 436g of tetrahydrofurfuryl alcohol and 0.5g of anhydrous aluminum chloride catalyst were added to a 3L reactor. The reactor was evacuated to -0.095MPa using a vacuum pump, and then purged with nitrogen to a pressure of 0.050MPa. The pressure was then reduced to -0.095MPa again, and the reactor was heated to 60℃. 564g of ethylene oxide was introduced into the reactor, and the pressure was kept below 0.45MPa during the introduction of ethylene oxide. After the addition of ethylene oxide, the reactor was kept at this temperature for 1.5 hours for curing. Unreacted ethylene oxide was removed from the reactor using a circulating water vacuum pump. The product was tested by GPC and found to have a molecular weight of approximately 234.29 and a molecular weight distribution of approximately 1.003.

[0042] (3) Compound IC (n=5)

[0043] 317g of tetrahydrofurfuryl alcohol and 0.5g of anhydrous zinc chloride catalyst were added to a 3L reactor. The reactor was evacuated to -0.095MPa using a vacuum pump, and then purged with nitrogen to a pressure of 0.050MPa. The pressure was then reduced to -0.095MPa again, and the reactor was heated to 60℃. 683g of ethylene oxide was introduced into the reactor, and the pressure was kept below 0.45MPa during the introduction of ethylene oxide. After the addition of ethylene oxide, the reactor was kept at this temperature for 1.6h for curing. Unreacted ethylene oxide was removed from the reactor using a circulating water vacuum pump. The product was tested by GPC and found to have a molecular weight of approximately 322.38 and a molecular weight distribution of approximately 1.002.

[0044] (4) Compound ID (n=10)

[0045] 188g of tetrahydrofurfuryl alcohol, 0.25g of anhydrous zinc chloride catalyst, and 0.25g of anhydrous aluminum chloride catalyst were added to a 3L reactor. The reactor was evacuated to -0.095MPa using a vacuum pump, and then purged with nitrogen to a pressure of 0.050MPa. The pressure was then reduced to -0.095MPa again, and the reactor was heated to 60℃. 812g of ethylene oxide was introduced into the reactor, and the pressure was kept below 0.45MPa during the introduction of ethylene oxide. After the addition of ethylene oxide, the reactor was kept at this temperature for 2.3 hours for curing. Unreacted ethylene oxide was removed from the reactor using a circulating water vacuum pump. The product was tested by GPC, and the molecular weight of the compound was approximately 542.63, with a molecular weight distribution of approximately 1.004.

[0046] (5) Compound IE (n=20)

[0047] 104g of tetrahydrofurfuryl alcohol and 1.0g of anhydrous aluminum chloride catalyst were added to a 3L reactor. The reactor was evacuated to -0.095MPa using a vacuum pump, and then purged with nitrogen to a pressure of 0.050MPa. The pressure was then reduced to -0.095MPa again, and the reactor was heated to 60℃. 896g of ethylene oxide was introduced into the reactor, and the pressure was kept below 0.45MPa during the introduction of ethylene oxide. After the addition of ethylene oxide, the reactor was kept at this temperature for 2 hours to mature. Unreacted ethylene oxide was removed from the reactor using a circulating water vacuum pump. The product was tested by GPC and found to have a molecular weight of approximately 983.13 and a molecular weight distribution of approximately 1.002.

[0048] Ethylene dimerization was carried out according to the following methods and experimental conditions, including the catalyst system in Table 1:

[0049] The ethylene dimerization reaction was carried out in a 1L Parr reactor. First, the reactor was cleaned, then heated to 160°C and dried under vacuum for 30 minutes, continuously purging with nitrogen. The reactor was then cooled to below 30°C, and 300 mL of solvent was added. The temperature was raised to the level shown in Table 1, and the catalyst system was added according to Table 1. Ethylene was introduced to the reaction pressure, and the reaction was carried out for 1 hour. After the reaction was completed, the pressure was released, the reaction solution was collected and weighed, the reaction activity was calculated, and the selectivity of the product and PE was determined by chromatography.

[0050] Table 1. Reaction conditions for examples and comparative examples

[0051]

[0052]

[0053] The performance testing methods involved in the specific embodiments of this invention are as follows:

[0054] (1) Reactivity: the mass of reaction products generated per unit mole of catalyst;

[0055] (2) 1-Butene selectivity: The percentage of characteristic peak area of ​​1-butene in the total product was determined by the area normalization method of gas chromatography as selectivity.

[0056] (3) PE generation: The weight of the by-product polymer in a certain amount of reaction solution after drying was determined by the differential method, and its mass ratio to the total product was calculated.

[0057] The reactivity and product selectivity of the above examples and comparative examples were tested respectively, and the results are shown in Table 2.

[0058] Table 2. Performance Tests of Examples and Comparative Examples

[0059]

[0060]

[0061] According to Tables 1 and 2, the catalyst system of the present invention exhibits high activity in ethylene dimerization, and the selectivity for 1-butene is significantly higher than that of Comparative Example 5. The polymer selectivity is significantly reduced to below 50 ppm. In actual production, this can effectively reduce the accumulation in the reactor or heat exchanger, and minimize the polymer wall adhesion effect caused by heat exchange through jackets or heat exchangers. Without changing the main process flow, it not only achieves high selectivity and reactivity of the reaction, but also effectively extends the equipment operating cycle and improves the stability of operation.

[0062] Specifically, comparing Examples 1-4 with Comparative Examples 1 and 4, it is shown that the necessity of adding organoaluminum and the reasonable amount of addition are important reasons for ensuring high selectivity of 1-butene and low selectivity of PE. Examples 2, 5-7 and Comparative Example 5 show that the necessary addition of the compound of Formula I proposed in this invention is the decisive factor in achieving high selectivity of ethylene dimerized dibutene-1 and low selectivity of PE, and the amount of compound of Formula I added has an important influence on the polymerization result.

[0063] In addition, this invention explored the lifespan of the catalyst systems in Example 2 and Comparative Examples 2, 5-7. First, the 10L reactor was cleaned, then heated to 160°C and dried under vacuum for 30 minutes, continuously purging with nitrogen. The reactor was cooled to below 30°C, 1L of solvent was added, the temperature was raised to 53°C, and the catalyst system was added according to the conditions in Table 1. Ethylene was introduced to the reaction pressure. During the reaction, the instantaneous conversion of ethylene was monitored using a flow meter, and the time when the catalyst activity significantly decreased was recorded as the catalyst lifespan.

[0064] Table 3. Catalyst lifetime test

[0065]

[0066]

[0067] As shown in Table 3, the catalyst system described in this invention has a longer catalytic life compared with comparative examples 2 and 5-7, and can further reduce the amount of catalyst used in industrial production, thus having high industrial value.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A catalyst for the dimerization of ethylene to 1-butene, characterized in that, The catalyst comprises the following components: a. an organic titanium compound; b. an organic aluminum compound; c. a compound represented by Formula I; In Formula I, n is an integer between 1 and 100. The amount of the organic aluminum compound relative to the organic titanium compound is (2-100):1 in terms of the molar ratio of metal Al to metal Ti. The molar ratio of the compound represented by Formula I to metal Al in the organic aluminum compound is (0.01-1):

1.

2. The catalyst for the dimerization of ethylene to 1-butene according to claim 1, characterized in that, In Formula I, n is an integer between 1 and 25.

3. The catalyst for the dimerization of ethylene to 1-butene according to claim 1, characterized in that, The organic titanium compound is a titanium alkoxide compound and / or a titanium aryloxide compound.

4. The catalyst for the dimerization of ethylene to 1-butene according to claim 3, characterized in that, The organic titanium compound is a titanium alkoxide compound and / or a titanium aryloxide compound.

5. The catalyst for the dimerization of ethylene to 1-butene according to claim 3, characterized in that, The organic titanium compound is selected from compounds represented by Formula II: Ti(OR)4 Formula II wherein R is selected from C1-C20 alkyl, C6-C30 aryl or alkylaryl.

6. The catalyst for the dimerization of ethylene to 1-butene according to claim 5, characterized in that, In Formula II, R is selected from methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, 2-methylethyl, 2-methylpropyl, pentyl, 2-methylbutyl, 3-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, hexyl, 2-methylpentyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, eicosyl, phenyl, benzyl, p-tolyl, o-tolyl, m-tolyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 4-methylphenyl, 2-phenylphenyl, 2,6-diphenylphenyl, 2,4,6-triphenylphenyl, 4-phenylphenyl, 2-t-butyl-6-phenylphenyl, 2,4-di-t-butyl-6-phenylphenyl, 2,6-diisopropylphenyl, 2,6-di-t-butylphenyl, 4-methyl-2,6-di-t-butylphenyl, 2,6-dichloro-4-t-butylphenyl, 2,6-dibromo-4-t-butylphenyl, biphenyl, binaphthyl, 1,8-dimethylnaphthyl.

7. Catalyst for the dimerization of ethylene to 1-butene according to any one of claims 1 to 6, characterized in that The organic aluminum compound is selected from at least one of an aluminum alkyl, an aluminoxane, and a chlorinated aluminum alkyl.

8. The catalyst for the dimerization of ethylene to 1-butene according to claim 7, characterized in that, The organic aluminum compound is selected from one or more of methylaluminoxane, modified methylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, monochloroethylaluminum, sesquiethylaluminum dichloroethylaluminum.

9. The catalyst for the dimerization of ethylene to 1-butene according to claim 7, characterized in that, The amount of the organic aluminum compound relative to the organic titanium compound is (2-30):1 in terms of the molar ratio of metal Al to metal Ti.

10. The catalyst for the dimerization of ethylene to 1-butene according to any one of claims 1 to 6, characterized in that, The molar ratio of the compound represented by Formula I to metal Al in the organic aluminum compound is (0.02-0.4):

1.

11. A process for the dimerization of ethylene to produce 1-butene, characterized in that, The ethylene polymerization reaction is carried out in the presence of the catalyst of any one of claims 1-10 at a reaction temperature of 20-150°C and a polymerization pressure of 2-5 MPa.

12. The process for the dimerization of ethylene to 1-butene according to claim 11, characterized in that, The reaction temperature is 30-60°C and the polymerization pressure is 2-3.5 MPa.

13. The process for the dimerization of ethylene to 1-butene according to claim 11, characterized in that, A solvent is added to the ethylene polymerization reaction system, and the solvent is selected from one or more of 1-butene, propane, butane, pentane, hexane, methylcyclohexane, heptane, octane, nonane, decane, Isopar solvent.

14. The process for the dimerization of ethylene to 1-butene according to any one of claims 11 to 13, characterized in that, The amount of the catalyst added to the polymerization reaction is 0.2-0.8 mmol / L in terms of the molar concentration of metal Ti in the solvent.

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