A catalyst system for ethylene oligomerization reaction and its preparation method and application

Abstract

The present invention provides a catalyst system for ethylene oligomerization reaction, its preparation method and application, the catalyst system comprising cyclohexane and a metal complex of 2-formyl-1,10-phenanthroline chloride condensation 2,6-dimethylaniline and ethylaluminoxane dissolved in the cyclohexane. The present invention adopts ethylaluminoxane as an aluminum adjuvant and cyclohexane as a solvent, which can effectively increase the temperature of the ethylene oligomerization reaction when using the metal complex catalyst of 2-formyl-1,10-phenanthroline chloride condensation 2,6-dimethylaniline. At the same time, the ethylene oligomerization reaction can be initiated rapidly, run smoothly, have good repeatability, and the catalyst has high catalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of ethylene oligomerization catalysis, and in particular to a catalyst system for ethylene oligomerization reaction, a preparation method and an application thereof. Background Art

[0002] Ethylene oligomerization is a key petrochemical reaction and the primary method for producing low-carbon linear α-olefins (C6-C18). Low-carbon linear α-olefins (C6-C10) are important chemical products with wide applications in the preparation of low-density polyethylene (LDPE), high-density polyethylene (HDPE), high-end detergents, higher alcohols, and advanced lubricants. 1-Hexene and 1-octene can be used as comonomers in linear low-density polyethylene (LLDPE), improving its tensile properties, impact resistance, environmental stress cracking resistance, heat resistance, flexibility, and transparency. 1-Decene can be used in the synthesis of polyα-olefin synthetic oils.

[0003] In 1998, the research groups of Brookhart and Gibson independently reported iron- and cobalt-based catalysts with bis-iminopyridine ligands. These catalysts exhibited high catalytic activity comparable to that of metallocene catalysts. Furthermore, by modifying the ligand backbone or the structure of the aromatic ring substituents, they could efficiently catalyze the non-selective oligomerization of ethylene. The resulting linear α-olefins exhibited a Schulz-Flory distribution with linear selectivities ≥95%, demonstrating promising applications. Consequently, these catalysts quickly became a hot topic in the field of ethylene oligomerization research and development, culminating in the subsequent development of a series of novel iron- and cobalt-based catalysts.

[0004] In recent years, Brookhart and Gibson have independently discovered that certain tridentate pyridineimine complexes of Fe(II) and Co(II) can catalyze ethylene oligomerization. These catalysts exhibit not only high catalytic activity but also high selectivity for α-olefins. However, these catalysts still suffer from numerous drawbacks during use. For example, the reaction requires relatively low temperatures, such as around 30°C. Because ethylene oligomerization is an exothermic reaction, cooling the reaction system is necessary. In existing technologies, chilled water is often used as a heat removal medium to achieve a reaction temperature around 30°C.

[0005] The disadvantages of using chilled water as a heat removal medium are obvious, mainly in that chilled water needs to be prepared from water. This process greatly increases the energy consumption required for the reaction and increases costs.

[0006] Therefore, it is necessary to improve a new catalyst system to solve the technical problem of too low reaction temperature when the tridentate pyridine imine complex of Fe(II) and Co(II) is used as a catalyst for ethylene polymerization in the prior art. Summary of the Invention

[0007] In order to solve the problems existing in the above-mentioned prior art, one of the objectives of the present invention is to provide a catalyst system for ethylene polymerization reaction, which adopts ethylaluminoxane as an aluminum auxiliary agent and cyclohexane as a solvent, and can effectively increase the temperature of the ethylene polymerization reaction when using a chloride-2-formyl-1,10-phenanthroline-2,6-dimethylaniline metal complex catalyst. At the same time, it can also make the ethylene polymerization reaction initiate quickly, run smoothly, have good repeatability, and the catalyst have high catalytic activity.

[0008] A second object of the present invention is to provide a method for preparing a catalyst system corresponding to the first object.

[0009] The third object of the present invention is to provide an application of a catalyst system corresponding to the above object.

[0010] To achieve one of the above purposes, the technical solution adopted by the present invention is as follows:

[0011] A catalyst system for ethylene oligomerization reaction comprises cyclohexane and a 2-formyl-1,10-phenanthroline-2,6-dimethylaniline metal complex and ethylaluminoxane dissolved in the cyclohexane.

[0012] In some preferred embodiments of the present invention, the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is selected from at least one of the compounds represented by formula (1).

[0013]

[0014] In formula (1), M is Fe(II), Co(II) or Ni(II), preferably Fe(II); R1-R6 are the same or different, and are each independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy and nitro, preferably selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy and nitro, and more preferably hydrogen.

[0015] In some preferred embodiments of the present invention, the ethylaluminoxane is a hydrolysis product of triethylaluminum, preferably ethylaluminoxane prepared by a method comprising the following steps:

[0016] S1. Dissolving triethylaluminum in cyclohexane to obtain a cyclohexane solution containing triethylaluminum;

[0017] S2. Under stirring conditions, contacting the cyclohexane solution containing triethylaluminum with water to generate the ethylaluminoxane;

[0018] Wherein, step S1 and step S2 are carried out under an inert atmosphere and / or ice bath conditions. Preferably, the inert atmosphere is a nitrogen atmosphere; the ice bath conditions include: a temperature of -10°C to 10°C, preferably -5°C to 5°C.

[0019] In some preferred embodiments of the present invention, in step S1, the amount of triethylaluminum used is 100 to 2000 μmol, preferably 300 to 1000 μmol, per milliliter of cyclohexane; and / or

[0020] In step S2, the stirring speed is 300 to 1000 r / min; and / or water is added dropwise to the cyclohexane solution containing triethylaluminum. Preferably, the amount of water added is 0.1 to 5 moles, preferably 0.8 to 1.2 moles, per mole of triethylaluminum.

[0021] In some preferred embodiments of the present invention, after the water is added dropwise, stirring is continued at a speed of 300 to 1000 r / min for 5 to 60 min, preferably 20 to 40 min; more preferably, after the water is added dropwise, stirring is continued at a constant speed for 5 to 60 min, preferably 20 to 40 min.

[0022] In some preferred embodiments of the present invention, in the catalyst system, based on the total volume of the catalyst system, the content of the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline metal complex is 1 μmol / L to 500 μmol / L, preferably 10 μmol / L to 300 μmol / L, and more preferably 10 μmol / L to 100 μmol / L.

[0023] In some preferred embodiments of the present invention, in the catalyst system, the molar ratio of aluminum in the ethylaluminoxane to M in the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is 30:1 to less than 900:1, preferably 100:1 to 700:1, and more preferably 148:1 to 196:1.

[0024] To achieve the second of the above objectives, the technical solutions adopted by the present invention are as follows:

[0025] A method for preparing the catalyst system according to any one of the above embodiments comprises contacting the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex, the ethylaluminoxane and the cyclohexane to obtain the catalyst system.

[0026] In some preferred embodiments of the present invention, the process comprises mixing a cyclohexane solution containing the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex and a solution containing the ethylaluminoxane to obtain the catalyst system.

[0027] To achieve the third of the above objectives, the technical solutions adopted by the present invention are as follows:

[0028] A catalyst system according to any one of the above embodiments or a catalyst system prepared according to any one of the above embodiments as a catalyst in an ethylene oligomerization reaction.

[0029] In some preferred embodiments of the present invention, the temperature of the ethylene oligomerization reaction is 40°C to 90°C, preferably 40°C to 80°C, and more preferably 50°C to 70°C.

[0030] The beneficial effects of the present invention are at least in the following aspects:

[0031] First, the products obtained by the ethylene polymerization reaction initiated by the catalyst system provided by the present invention include C4, C6, C8, C 10 、C 12 、C 14 、C 16 、C 18 、C 20 、C 22 The olefins were synthesized, and the selectivity for α-olefins reached over 96%. GC analysis after the ethylene oligomerization reaction was completed indicated high oligomerization activity. Furthermore, no polymer was obtained when the remaining reaction mixture was neutralized with 5% dilute hydrochloric acid in ethanol.

[0032] Secondly, the catalyst system provided by the present invention has a rapid initiation of the polymerization reaction, stable operation, good repeatability, and the reaction can be carried out within a relatively high temperature range (above 40°C, or even above 50°C), thereby overcoming the technical prejudices of those skilled in the art and achieving unexpected technical effects. DETAILED DESCRIPTION

[0033] The present invention is described in detail below through examples, but the protection scope of the present invention is not limited to the following description.

[0034] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are conventional products that can be obtained through commercial channels.

[0035] In the following embodiments, the cyclohexane used is all anhydrous cyclohexane.

[0036] In the following embodiments, all water used is distilled water at room temperature. In the present invention, room temperature refers to the room temperature during the experiment, which is about 25°C to 30°C.

[0037] In the following embodiments, unless otherwise specified, condensed water is used as the heat removal medium.

[0038] Preparation Example 1

[0039] Under nitrogen protection and ice bath conditions (0°C), the following operation was performed: 715 μmol of triethylaluminum was dissolved in 1 mL of cyclohexane, and then water was slowly added dropwise to the resulting solution under stirring conditions (300 rpm) (the amount of water added was such that the final molar ratio of water to triethylaluminum was 1:1). After the water addition was completed, stirring was continued for 30 minutes while maintaining the speed constant to obtain an ethylaluminoxane solution. Based on the amount of raw materials used, the concentration of ethylaluminoxane in the resulting ethylaluminoxane solution was calculated to be 715 μmol / mL.

[0040] Preparation Example 2

[0041] Under nitrogen protection and ice bath conditions (0°C), the following operation was performed: 715 μmol of triethylaluminum was dissolved in 1 mL of toluene, and then water was slowly added dropwise to the resulting solution under stirring conditions (300 rpm) (the amount of water added was such that the final molar ratio of water to triethylaluminum was 1:1). After the water addition was completed, stirring was continued for 30 minutes while maintaining the speed constant to obtain an ethylaluminoxane solution. Based on the amount of raw materials used, the concentration of ethylaluminoxane in the resulting ethylaluminoxane solution was calculated to be 715 μmol / mL.

[0042] Preparation Example 3

[0043] Under nitrogen protection and ice bath conditions (0°C), the following operation was performed: 715 μmol of trimethylaluminum was dissolved in 1 mL of cyclohexane, and then water was slowly added dropwise to the resulting solution under stirring conditions (300 rpm) (the amount of water added was such that the final molar ratio of water to trimethylaluminum was 1:1). After the water addition was completed, stirring was continued for 30 minutes while maintaining the speed constant to obtain a methylaluminoxane solution. Based on the amount of raw materials used, it can be calculated that the concentration of methylaluminoxane in the resulting methylaluminoxane solution was 715 μmol / mL.

[0044] Preparation Example 4

[0045] The process was basically carried out in the manner of Preparation Example 1, except that the amount of water added was adjusted so that the final molar ratio of water to triethylaluminum was 0.9:1.

[0046] Preparation Example 5

[0047] The process was basically carried out in the manner of Preparation Example 1, except that the amount of water added was adjusted so that the final molar ratio of water to triethylaluminum was 0.8:1.

[0048] Preparation Example 6

[0049] The process was basically carried out in the manner of Preparation Example 1, except that the amount of water added was adjusted so that the final molar ratio of water to triethylaluminum was 0.5:1.

[0050] Preparation Example 7

[0051] The process was basically carried out in the manner of Preparation Example 1, except that the amount of water added was adjusted so that the final molar ratio of water to triethylaluminum was 1.2:1.

[0052] Preparation Example 8

[0053] The process was basically carried out in the manner of Preparation Example 1, except that the amount of water added was such that the final molar ratio of water to triethylaluminum was 3:1.

[0054] Example 1

[0055] (1) Replace the reactor through high-temperature drying, vacuum replacement and other operations to ensure that there is no water and oxygen in the reactor;

[0056] (2) replacing the reactor with ethylene to place the reactor in an ethylene environment;

[0057] (3) Anhydrous cyclohexane solvent was added to the reactor, followed by 1.37 mL of the ethylaluminoxane solution prepared in Preparation Example 1, and 2 mL of anhydrous cyclohexane solution of a 2-formyl-1,10-phenanthroline-2,6-dimethylaniline iron (II) chloride complex (the concentration of the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline iron (II) chloride complex was 2.5 μmol / mL). The total amount of the catalyst composition was adjusted to 100 mL, wherein the Al / Fe (molar ratio) was 196. After sufficient stirring, ethylene was introduced to initiate the oligomerization reaction.

[0058] (4) maintaining the ethylene pressure at 1 MPa and the reaction temperature at 55°C for 30 min;

[0059] (5) Stop the reaction, take out a small amount of the reaction product and analyze it by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0060] Example 2

[0061] The reaction was carried out essentially in the same manner as in Preparation Example 1, except that the ethylaluminoxane solution prepared in Preparation Example 4 was used instead of the ethylaluminoxane solution prepared in Preparation Example 1. After the reaction was terminated, a small amount of the reaction product was removed and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0062] Example 3

[0063] The reaction was carried out essentially in the same manner as in Preparation Example 1, except that the ethylaluminoxane solution prepared in Preparation Example 5 was used instead of the ethylaluminoxane solution prepared in Preparation Example 1. After the reaction was terminated, a small amount of the reaction product was removed and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0064] Example 4

[0065] The reaction was carried out essentially in the same manner as in Preparation Example 1, except that the ethylaluminoxane solution prepared in Preparation Example 6 was used instead of the ethylaluminoxane solution prepared in Preparation Example 1. After the reaction was terminated, a small amount of the reaction product was removed and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0066] Example 5

[0067] The reaction was carried out essentially in the same manner as in Preparation Example 1, except that the ethylaluminoxane solution prepared in Preparation Example 7 was used instead of the ethylaluminoxane solution prepared in Preparation Example 1. After the reaction was terminated, a small amount of the reaction product was removed and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0068] Example 6

[0069] The reaction was carried out essentially in the same manner as in Preparation Example 1, except that the ethylaluminoxane solution prepared in Preparation Example 8 was used instead of the ethylaluminoxane solution prepared in Preparation Example 1. After the reaction was terminated, a small amount of the reaction product was removed and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0070] Example 7

[0071] The preparation was carried out basically in the manner of Preparation Example 1, except that “2-formyl-1,10-phenanthroline-2,6-diethylaniline iron (II) complex chloride” was used to replace the “2-formyl-1,10-phenanthroline-2,6-dimethylaniline iron (II) complex chloride” in Example 1.

[0072] After the reaction was stopped, a small amount of the reaction product was taken out and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0073] Example 8

[0074] The only difference from Example 1 is that the reaction temperature is 55°C.

[0075] After the reaction was stopped, a small amount of the reaction product was taken out and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0076] Example 9

[0077] The only difference from Example 1 is that the reaction temperature is 60°C.

[0078] After the reaction was stopped, a small amount of the reaction product was taken out and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0079] Comparative Example 1

[0080] The reaction was carried out essentially in the same manner as in Preparation Example 1, except that the ethylaluminoxane solution prepared in Preparation Example 2 was used in place of the ethylaluminoxane solution prepared in Preparation Example 1, and the cyclohexane solution in Example 1 was replaced with a toluene solution. After the reaction was terminated, a small amount of the reaction product was removed and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0081] Comparative Example 2

[0082] The reaction was carried out essentially in the same manner as in Preparation Example 1, except that the ethylaluminoxane solution prepared in Preparation Example 3 was used instead of the ethylaluminoxane solution prepared in Preparation Example 1. After the reaction was terminated, a small amount of the reaction product was removed and analyzed by gas chromatography (GC). The specific analysis results are shown in Table 1.

[0083] Table 1

[0084]

[0085] From the data in Table 1 above, we can see that

[0086] First, the catalyst composition provided by the present invention has a high oligomerization activity. When ethylene is subjected to an oligomerization reaction in the presence of the catalyst composition provided by the present invention, the oligomerization reaction can be initiated rapidly.

[0087] Secondly, the content of undesirable C4 impurities in the oligomerization product is low, and the product distribution coefficient is high, indicating that the reaction system initiated by the catalyst composition provided by the present invention runs smoothly and has good reproducibility;

[0088] Third, the catalyst composition provided by the present invention can react at a higher reaction temperature, which is easier to achieve than the reaction temperature of 30°C to 40°C commonly used in the art. As a result, condensed water can be used as a reaction heat removal medium, which reduces energy consumption compared to the chilled water required when using a reaction temperature of 30°C to 40°C as a reaction heat removal medium, and significantly improves its industrial application value.

[0089] Fourthly, as the reaction temperature increases, the catalyst composition provided by the present invention still maintains a high activity.

[0090] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A catalyst system for ethylene oligomerization, comprising cyclohexane and a metal complex of 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride and ethylaluminoxane dissolved in the cyclohexane; in, The ethylaluminoxane is ethylaluminoxane prepared by a method comprising the following steps: S1. Dissolving triethylaluminum in cyclohexane to obtain a cyclohexane solution containing triethylaluminum; S2. Under stirring conditions, contacting the cyclohexane solution containing triethylaluminum with water to generate the ethylaluminoxane; The amount of water added is 0.8 to 1.2 moles per mole of triethylaluminum; The 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is selected from at least one of the compounds shown in formula (1). Formula (1) In formula (1), M is Fe(II), Co(II) or Ni(II); R1-R6 are the same or different and are independently selected from hydrogen, C1-C6 alkyl, halogen, C1-C6 alkoxy or nitro.

2. The catalyst system according to claim 1, characterized in that In formula (1), M is Fe(II).

3. The catalyst system according to claim 1 or 2, characterized in that In formula (1), R1-R6 are the same or different and are independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, fluorine, chlorine, bromine, methoxy, ethoxy or nitro.

4. The catalyst system according to claim 1 or 2, characterized in that In formula (1), R1-R6 are hydrogen.

5. The catalyst system according to claim 1 or 2, characterized in that Step S1 and step S2 are performed under an inert atmosphere and / or in an ice bath.

6. The catalyst system according to claim 5, characterized in that The inert atmosphere is a nitrogen atmosphere; the ice bath conditions include: a temperature of -10°C to 10°C.

7. The catalyst system according to claim 6, characterized in that The ice bath conditions include: a temperature of -5°C to 5°C.

8. The catalyst system according to claim 1 or 2, characterized in that In step S1, the amount of triethylaluminum used is 100-2000 μmol per milliliter of cyclohexane.

9. The catalyst system according to claim 8, characterized in that In step S1, the amount of triethylaluminum used is 300-1000 μmol per milliliter of cyclohexane.

10. The catalyst system according to claim 1 or 2, characterized in that In step S2, the stirring speed is 300-1000 r / min.

11. The catalyst system according to claim 1 or 2, characterized in that In step S2, water is added dropwise to the cyclohexane solution containing triethylaluminum.

12. The catalyst system according to claim 11, characterized in that After the water addition is completed, continue stirring at a speed of 300~1000r / min for 5min~60min.

13. The catalyst system according to claim 12, characterized in that After the water addition is completed, continue stirring at a speed of 300~1000r / min for 20min~40min.

14. The catalyst system according to claim 11, characterized in that After the water addition is completed, keep the stirring speed unchanged and continue stirring for 5 minutes to 60 minutes.

15. The catalyst system according to claim 11, characterized in that After the water addition is completed, keep the stirring speed unchanged and continue stirring for 20 minutes to 40 minutes.

16. The catalyst system according to claim 1 or 2, characterized in that In the catalyst system, the content of the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is 1 μmol / L to 500 μmol / L, based on the total volume of the catalyst system.

17. The catalyst system according to claim 16, characterized in that In the catalyst system, the content of the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is 10 μmol / L to 300 μmol / L, based on the total volume of the catalyst system.

18. The catalyst system according to claim 17, characterized in that In the catalyst system, the content of the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is 10 μmol / L to 100 μmol / L, based on the total volume of the catalyst system.

19. The catalyst system according to claim 1 or 2, characterized in that In the catalyst system, the molar ratio of aluminum in the ethylaluminoxane to M in the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is 30:1 to less than 900:

1.

20. The catalyst system according to claim 19, characterized in that In the catalyst system, the molar ratio of aluminum in the ethylaluminoxane to M in the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is 100:1 to 700:

1.

21. The catalyst system according to claim 20, characterized in that In the catalyst system, the molar ratio of aluminum in the ethylaluminoxane to M in the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride metal complex is 148:1 to 196:

1.

22. A method for preparing the catalyst system according to any one of claims 1 to 21, comprising: The 2-formyl-1,10-phenanthroline-2,6-dimethylaniline chloride-based metal complex, the ethylaluminoxane and the cyclohexane are contacted to obtain the catalyst system.

23. The preparation method according to claim 22, characterized in that include: The catalyst system is obtained by mixing a cyclohexane solution in which the 2-formyl-1,10-phenanthroline-2,6-dimethylaniline metal complex is dissolved and a solution in which the ethylaluminoxane is dissolved.

24. Use of the catalyst system according to any one of claims 1 to 21 or the catalyst system prepared by the preparation method according to claim 22 or 23 as a catalyst in ethylene oligomerization reaction.

25. The use according to claim 24, characterized in that The temperature of the ethylene oligomerization reaction is 40°C to 90°C.

26. The use according to claim 25, characterized in that The temperature of the ethylene oligomerization reaction is 40°C to 80°C.

27. The use according to claim 26, characterized in that The temperature of the ethylene oligomerization reaction is 50°C to 70°C.

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