The invention relates to a method for synthesizing 4, 4apos; the invention relates to a cobalt-based catalyst based on 4, 4 apos, 1, 1, 2-bipyridine and 4, 4 Synthesis method of-dipyridyl

Abstract

The invention discloses a cobalt-based catalyst for synthesizing a 4, 4 '-bipyridine compound, the cobalt-based catalyst takes MZSM-5 zeolite as a carrier and Co as an active component, and the loading capacity of Co is 1-3 wt.%. According to the present invention, the MZSM-5 zeolite has the mesoporous level structure and the large specific surface area, and the Co / MZSM-5 prepared by using the MZSM-5 zeolite as the carrier can provide the well-distributed metal active sites and the rich acid sites for the reaction, is used for catalyzing the pyridine to synthesize the 4, 4 '-dipyridyl, and has the high pyridine conversion rate and the high 4, 4'-dipyridyl selectivity; the invention also discloses a synthesis method of 4, 4 '-dipyridyl, which comprises the following steps: adding pyridine, a cobalt-based catalyst and a reaction solvent into a reaction tube, and reacting to obtain 4, 4'-dipyridyl.

Description

Technical Field

[0001] The invention belongs to the field of heterogeneous catalytic organic synthesis and the technical field of organic synthetic chemistry, and relates to a heterogeneous catalyst, specifically to a cobalt-based catalyst for synthesizing 4,4'-bipyridine and a preparation method thereof, and a method for synthesizing 4,4'-bipyridine from pyridine using a heterogeneous catalyst. Background Art

[0002] 4,4'-Bipyridine is an important nitrogen-containing heterocyclic compound that is widely present in various natural products, medicines and functional materials. It is also a key intermediate in agricultural chemicals and flow battery electrolytes. Due to its wide application in fine chemicals and energy storage, a variety of synthetic methods for 4,4'-bipyridine have been developed.

[0003] In recent years, the metal-catalyzed preparation of 4,4'-bipyridine has attracted considerable attention, such as: (1) Palladium-catalyzed Suzuki coupling reaction of 4-halopyridine (RSC Adv., 2018, 8, 13643-13648); (2) Sodium-catalyzed coupling oxidation of pyridine (CN108349892A); (3) Copper-catalyzed coupling of arylboronic acid (RSC Adv., 2022, 12, 4931-4938). However, these methods have many disadvantages, such as high reaction temperature, strict anhydrous and oxygen-free conditions, large amounts of by-products generated during the reaction, poor thermal stability of the catalyst, and the need for additional additives. These disadvantages not only limit the industrial production application, but also fail to meet the chemical community's pursuit of sustainable green synthesis. Summary of the invention

[0004] The present invention aims to overcome the deficiencies of the prior art and provide a cobalt-based catalyst (Co / MZSM-5) for synthesizing 4,4'-bipyridine, wherein the cobalt-based catalyst is a heterogeneous catalyst. The present invention also provides a green, mild, economical, high-yield, easy-to-separate and purify, environmentally friendly method for synthesizing 4,4'-bipyridine, wherein the pyridine coupling synthesis of 4,4'-bipyridine can be achieved under mild conditions by using the heterogeneous catalyst Co / MZSM-5.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A cobalt-based catalyst for synthesizing 4,4'-bipyridine compounds. The cobalt-based catalyst uses MZSM-5 zeolite as a carrier and Co as an active component. The loading amount of Co is 1-3 wt.%.

[0007] Preferably, in the cobalt-based catalyst, the loading amount of Co is 1 wt.%.

[0008] Preferably, the cobalt-based catalyst is a Co-loaded catalyst obtained by impregnating equal volumes of MZSM-5 zeolite and cobalt nitrate solution, and then standing at room temperature, drying and calcining; wherein the drying temperature is 80-120°C; and the calcining temperature is 400-500°C.

[0009] Preferably, the cobalt nitrate solution is a cobalt nitrate aqueous solution.

[0010] Preferably, the MZSM-5 zeolite is prepared by the following method: 13.0-20.0 mL of water glass, 0.3-0.7 g of NaOH and 15.0-25.0 mL of distilled water are mixed, stirred for 30 min, 2.0-5.0 mL of quaternary ammonium salt template is added, stirring is continued for 2 h, and finally 5.0-15.0 mL of sulfuric acid (0.2 mol / L), 5.0-15.0 mL of water and 0.5-1.5 mL of 98% concentrated sulfuric acid are added, stirring is continued for 4 h, and then high-temperature crystallization, filtration, drying and calcination are sequentially performed to obtain the MZSM-5 zeolite. Wherein, the crystallization temperature is 150-200 ° C, the crystallization time is 48-72 h; the calcination temperature is 400-570 ° C.

[0011] The content of SiO2 in the water glass (Na2O·nSiO2, n is the molar ratio of SiO2 to Na2O, called the molar number of water glass) is 26-29wt.%, and the modulus is 3.1-3.4.

[0012] The quaternary ammonium salt template is N,N,N-trimethyl-1-adamantyl ammonium hydroxide.

[0013] Another object of the present invention is to provide the use of the cobalt-based catalyst in catalyzing the synthesis of 4,4'-bipyridine from pyridine

[0014] Another object of the present invention is to provide a method for synthesizing 4,4'-bipyridine, comprising: adding pyridine, a cobalt-based catalyst and a reaction solvent into a reaction tube, and reacting to obtain 4,4'-bipyridine.

[0015] The dosage ratio of pyridine to the cobalt-based catalyst is 0.5:20 to 0.5:80 mmol / mg, preferably 0.5:40 to 0.5:60 mmol / mg, and more preferably 0.5:40 mmol / mg.

[0016] The dosage ratio of pyridine to the reaction solvent is 0.5:1 to 0.5:4 mmol / mL, preferably 0.5:2 to 0.5:4 mmol / mL, and more preferably 0.5:2 mmol / mL.

[0017] The reaction solvent may be one of dimethyl sulfoxide, acetonitrile, toluene and 1,4-dioxane, preferably dimethyl sulfoxide or acetonitrile, more preferably dimethyl sulfoxide.

[0018] The reaction temperature is 60-100° C., preferably 80-100° C., more preferably 90-100° C.; the reaction time is 4-8 h, preferably 7-8 h.

[0019] As a further preferred technical scheme of the preparation method of 4,4'-bipyridine of the present invention, the method further includes centrifuging and filtering to separate the cobalt-based catalyst after the reaction is completed, adding saturated brine and ethyl acetate to the filtrate for extraction, taking the organic layer, concentrating the organic layer under reduced pressure to obtain a crude product, and subjecting the crude product to silica gel column chromatography to separate and purify the 4,4'-bipyridine.

[0020] The eluent of the silica gel column chromatography is petroleum ether:ethyl acetate in a volume ratio of 5:1 to 20:1.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) MZSM-5 zeolite has a mesoporous structure and a large specific surface area. Co / MZSM-5 prepared with it as a carrier can provide well-distributed metal active sites and abundant acidic sites for the reaction, which can be used to catalyze the synthesis of 4,4'-bipyridine from pyridine, with high pyridine conversion rate and high 4,4'-bipyridine selectivity.

[0023] (2) The preparation process of Co / MZSM-5 catalyst is simple, easy to separate and recover, and can be reused.

[0024] (3) The preparation method of 4,4'-bipyridine of the present invention does not use the traditional homogeneous catalytic system containing soluble metal salts, ligands and various additives, but uses Co-containing acidic mesoporous silica-alumina zeolite to synthesize 4,4'-bipyridine. The Co / MZSM-5 catalytic system avoids the use of soluble metal salts and additives and has excellent conversion rate and selectivity. The catalyst of the reaction system is easy to separate and recover from the product and can be reused, which simplifies the reaction system and reduces the emission of reaction waste. The method is simple to operate, green and environmentally friendly, in line with the development concept of green chemistry, and has the advantages of simple operation and mild reaction conditions. It shows great application potential in the synthesis of 4,4'-bipyridine, an intermediate of pesticides and liquid flow battery electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD pattern of Co / MZSM-5.

[0026] Figure 2The nitrogen adsorption-desorption curve and pore size distribution diagram of Co / MZSM-5.

[0027] Figure 3 This is the ammonia temperature-programmed desorption diagram of Co / MZSM-5. DETAILED DESCRIPTION

[0028] The technical scheme of the present invention is further illustrated below in conjunction with the accompanying drawings and specific examples. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0029] Silicalite-1 molecular sieve and ETS-10 molecular sieve were purchased from the market.

[0030] Example 1

[0031] Preparation of mesoporous ZSM-5 (MZSM-5) zeolite:

[0032] MZSM-5 zeolite is synthesized under hydrothermal conditions using macromolecular quaternary ammonium salt as mesoporous template, and the process is as follows: 17.6mL of water glass (26wt.%SiO2, 8wt.%Na2O, 66wt.%H2O), 0.5g of NaOH and 20.0mL of distilled water are mixed and stirred for 30min, and then 3.0mL of N,N,N-trimethyl-1-adamantyl ammonium hydroxide (CAS No.: 53075-09-5) is added, and stirring is continued for 2h, and finally 10.0mL of sulfuric acid (0.2mol / L), 8.4mL of water and 0.7mL of 98% concentrated sulfuric acid are added, and stirring is continued for 4h, and the mixture is loaded into a kettle, crystallized at a temperature of 170℃ for 60h, filtered, dried, and calcined at a temperature of 550℃ for 4h. The obtained sample is MZSM-5 zeolite.

[0033] Preparation of Co / MZSM-5:

[0034] Weigh 0.2 g of cobalt nitrate hexahydrate and dissolve it in 3.7 g of water to obtain a cobalt nitrate solution. The cobalt nitrate solution and 4.0 g of MZSM-5 zeolite are evenly mixed, allowed to stand at room temperature for 6 h, dried at 120° C., and calcined at 450° C. to obtain a cobalt-based catalyst (denoted as Co / MZSM-5) with a Co loading of 1 wt.%.

[0035] like Figure 1 As shown, the Co / MZSM-5 catalyst has high crystallinity, no other crystalline impurities, and the metal Co species are evenly distributed on the surface and pores of the MZSM-5 zeolite without obvious metal agglomeration.

[0036] like Figure 2As shown, the Co / MZSM-5 catalyst has a typical type IV hysteresis loop adsorption isotherm, indicating that Co / MZSM-5 has a good mesoporous structure, and the mesopore size is mainly distributed around 24.2 nm. The large mesopore size is conducive to reaction mass transfer and improves the catalytic activity.

[0037] like Figure 3 As shown, the acid strength of Co / MZSM-5 catalyst is mainly distributed in the medium-strong acid range (200-400°C), the acid adsorption amount is large, and it has good acidic properties.

[0038] Preparation of Co / Silicalite-1:

[0039] Referring to the preparation of Co / MZSM-5, the MZSM-5 zeolite was replaced with an equal amount of Silicalite-1 molecular sieve to prepare Co / Silicalite-1.

[0040] Preparation of Co / ETS-10:

[0041] Referring to the preparation of Co / MZSM-5, MZSM-5 zeolite was replaced with ETS-10 molecular sieve to prepare Co / ETS-10.

[0042] Example 2

[0043] 0.5mmol pyridine and 40mg Co / MZSM-5 were added to a 10mL quartz reaction tube, followed by 2mL dimethyl sulfoxide, and the quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, centrifuged and filtered to separate the solid Co / MZSM-5 catalyst, and a filtrate was obtained (the filtrate was subjected to gas chromatography analysis to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine), 20mL saturated brine and 10mL ethyl acetate were added to the filtrate for extraction, and the upper organic phase was taken, and the organic phase was concentrated under reduced pressure to obtain a crude product, and the crude product was subjected to silica gel column chromatography (200-300 mesh silica gel, eluent is petroleum ether: ethyl acetate volume ratio = 5:1 to 20:1), and 4,4'-bipyridine product was separated and purified, and the purity was 99.6%.

[0044] Comparative Example 1

[0045] 0.5 mmol pyridine was added to a 10 mL quartz reaction tube, followed by 2 mL dimethyl sulfoxide, and the quartz reactor was placed in a heater, the reaction temperature was controlled at 100 ° C, and the reaction was stirred for 8 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the reaction liquid was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0046] Comparative Example 2

[0047] 0.5mmol pyridine and 40mg MZSM-5 were added to a 10mL quartz reaction tube in sequence, followed by 2mL dimethyl sulfoxide. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid MZSM-5 was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0048] Comparative Example 3

[0049] 0.5mmol pyridine and 40mg Co / Silicalite-1 were added to a 10mL quartz reaction tube in sequence, followed by 2mL dimethyl sulfoxide. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid Co / Silicalite-1 catalyst was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0050] Comparative Example 4

[0051] 0.5 mmol pyridine and 40 mg Co / ETS-10 were added to a 10 mL quartz reaction tube in sequence, followed by 2 mL dimethyl sulfoxide. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100 ° C, and the reaction was stirred for 8 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the solid Co / ETS-10 catalyst was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0052] Table 1: Effect of catalyst on reaction

[0053] catalyst Conversion rate (%) Selectivity (%) Comparative Example 1 - 0 0 Comparative Example 2 MZSM-5 0 0 Example 2 Co / MZSM-5 92 98 Comparative Example 3 Co / Silicalite-1 63 91 Comparative Example 4 Co / ETS-10 47 84

[0054] As shown in Table 1, when no catalyst is used or only MZSM-5 zeolite is used as a catalyst, no product is generated. When Co / Silicalite-1 with neutral Silicalite-1 molecular sieve as a carrier and Co / ETS-10 with alkaline ETS-10 molecular sieve as a carrier are used as catalysts, although they also have certain catalytic activity, they are still inferior to the catalytic yield of Co / MZSM-5 catalyst using acidic mesoporous zeolite MZSM-5 as a carrier. This may be because the acidic sites of zeolite can coordinate with the nitrogen lone pair electrons on the pyridine molecule, improve the reaction activity of the pyridine molecule, and facilitate the metal-catalyzed coupling oxidation of pyridine to generate 4,4'-bipyridine.

[0055] Example 3

[0056] 0.5mmol pyridine and 60mg Co / MZSM-5 were added to a 10mL quartz reaction tube in sequence, followed by 2mL dimethyl sulfoxide. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid MZSM-5 was separated by centrifugation and filtration to obtain a filtrate. The filtrate was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0057] Example 4

[0058] 0.5mmol pyridine and 80mg Co / MZSM-5 were added to a 10mL quartz reaction tube in sequence, followed by 2mL dimethyl sulfoxide. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid MZSM-5 was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0059] Table 2: Effect of catalyst amount on reaction

[0060]

[0061]

[0062] As shown in Table 2, Co / MZSM-5 can catalyze the synthesis of 4,4'-bipyridine from pyridine; when the ratio of pyridine to catalyst is 0.5:40 mmol / mg, the reaction has excellent conversion rate and selectivity; with the increase of catalyst amount, although the conversion rate increases, the selectivity decreases due to the catalytic activity of more metal active sites, but it can still maintain a high 4,4'-bipyridine yield.

[0063] Example 5

[0064] 0.5mmol pyridine and 40mg Co / MZSM-5 were added to a 10mL quartz reaction tube, followed by 2mL acetonitrile, and the quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid Co / MZSM-5 was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0065] Comparative Example 5

[0066] 0.5mmol pyridine and 40mg Co / MZSM-5 were added to a 10mL quartz reaction tube, followed by 2mL toluene. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction, the reaction system was cooled to room temperature, and the solid Co / MZSM-5 was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0067] Comparative Example 6

[0068] 0.5mmol pyridine and 40mg Co / MZSM-5 were added to a 10mL quartz reaction tube, followed by 2mL 1,4-dioxane, and the quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid Co / MZSM-5 was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0069] Table 3: Effect of solvent on reaction

[0070] Solvents Conversion rate (%) Selectivity (%) Example 2 Dimethyl sulfoxide 92 98 Example 5 Acetonitrile 86 91 Comparative Example 5 Toluene 74 63 Comparative Example 6 1,4-Dioxane 90 72

[0071] It can be seen from Table 3 that although different solvents can obtain the target product, when dimethyl sulfoxide or acetonitrile is used as the solvent, the conversion rate of pyridine and the selectivity of 4,4'-bipyridine are relatively better, especially when dimethyl sulfoxide is used as the solvent, the conversion rate of pyridine and the selectivity of 4,4'-bipyridine are the best.

[0072] Example 6

[0073] 0.5mmol pyridine and 40mg Co / MZSM-5 were added to a 10mL quartz reaction tube, followed by 3mL dimethyl sulfoxide. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid Co / MZSM-5 was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0074] Example 7

[0075] 0.5mmol pyridine and 40mg Co / MZSM-5 were added to a 10mL quartz reaction tube, followed by 4mL dimethyl sulfoxide. The quartz reactor was placed in a heater, the reaction temperature was controlled at 100°C, and the reaction was stirred for 8h. After the reaction was completed, the reaction system was cooled to room temperature, and the solid Co / MZSM-5 was separated by centrifugation and filtration to obtain a filtrate, which was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0076] Table 4: Effect of dimethyl sulfoxide solvent amount on the reaction

[0077] Pyridine:Solvent (mmol / mL) Conversion rate (%) Selectivity (%) Example 2 0.5:2 92 98 Example 6 0.5:3 91 97 Example 7 0.5:4 91 98

[0078] It can be seen from Table 4 that with the increase in the amount of reaction solvent, the conversion rate and selectivity of the reaction did not increase significantly. Considering industrial economic efficiency, the most appropriate ratio of pyridine to solvent is 0.5:2 mmol / mL.

[0079] Comparative Example 7

[0080] 0.5 mmol pyridine and 40 mg Co / MZSM-5 were added to a 10 mL quartz reaction tube, followed by 2 mL dimethyl sulfoxide, and the quartz reactor was placed in a heater, the reaction temperature was controlled at 60 ° C, and the reaction was stirred for 8 hours. After the reaction was completed, the reaction system was cooled to room temperature, centrifuged and filtered to separate the solid Co / MZSM-5 catalyst, the filtrate was collected, and the filtrate was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0081] Example 8

[0082] 0.5 mmol pyridine and 40 mg Co / MZSM-5 were added to a 10 mL quartz reaction tube, followed by 2 mL dimethyl sulfoxide, and the quartz reactor was placed in a heater, the reaction temperature was controlled at 80 ° C, and the reaction was stirred for 8 hours. After the reaction was completed, the reaction system was cooled to room temperature, centrifuged, filtered, and the filtrate was collected. The filtrate was analyzed by gas chromatography to calculate the conversion rate of pyridine and the selectivity of 4,4'-bipyridine.

[0083] Table 5: Effect of reaction temperature on reaction

[0084] catalyst Reaction temperature (℃) Conversion rate (%) Selectivity (%) Comparative Example 7 Co / MZSM-5 60 51 97 Example 8 Co / MZSM-5 80 79 98 Example 2 Co / MZSM-5 100 92 98

[0085] The above describes the optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art. In order to teach the scheme of the present invention, some conventional technical aspects have been simplified and omitted. Those skilled in the art should understand that variations derived from this aspect are all within the scope of protection of the present invention.

Claims

1. A cobalt-based catalyst for synthesizing 4,4'-bipyridine, characterized in that: The cobalt-based catalyst uses MZSM-5 zeolite as a carrier and Co as an active component, and the loading amount of Co is 1-3wt.%.

2. The cobalt-based catalyst according to claim 1, characterized in that: The loading amount of Co was 1 wt.%.

3. The cobalt-based catalyst according to claim 1, characterized in that: The cobalt-based catalyst is a Co-loaded catalyst obtained by impregnating equal volumes of MZSM-5 zeolite and cobalt nitrate solution, standing at room temperature, drying and calcining, wherein the drying temperature is 80-120°C; the calcining temperature is 400-500°C.

4. The cobalt-based catalyst according to claim 1, characterized in that: The MZSM-5 zeolite is prepared by the following method: 13.0-20.0 mL of water glass, 0.3-0.7 g of NaOH and 15.0-25.0 mL of distilled water are mixed, stirred for 30 minutes, 2.0-5.0 mL of a quaternary ammonium salt template is added, stirring is continued for 2 hours, and finally 5.0-15.0 mL of 0.2 mol / L sulfuric acid, 5.0-15.0 mL of water and 0.5-1.5 mL of 98% concentrated sulfuric acid are added, stirring is continued for 4 hours, and then high-temperature crystallization, filtration, drying and calcination are sequentially performed to obtain the MZSM-5 zeolite; wherein the crystallization temperature is 150-200° C., the crystallization time is 48-72 hours, and the calcination temperature is 400-570° C.

5. The cobalt-based catalyst according to claim 4, characterized in that: The content of SiO2 in the water glass is 26-29wt.%, and the modulus is 3.1-3.4; the quaternary ammonium salt template is N,N,N-trimethyl-1-adamantyl ammonium hydroxide.

6. Use of the cobalt-based catalyst according to claim 1 in catalyzing the synthesis of 4,4'-bipyridine from pyridine.

7. A method for synthesizing 4,4'-bipyridine, characterized in that: include: Pyridine, a cobalt-based catalyst and a reaction solvent are added into a reaction tube to react to obtain 4,4'-bipyridine; wherein the reaction solvent is one of dimethyl sulfoxide, acetonitrile, toluene and 1,4-dioxane, preferably dimethyl sulfoxide or acetonitrile, more preferably dimethyl sulfoxide.

8. The method for synthesizing 4,4'-bipyridine according to claim 7, characterized in that: The dosage ratio of pyridine to the cobalt-based catalyst is 0.5:20 to 0.5:80 mmol / mg, preferably 0.5:40 to 0.5:60 mmol / mg, and more preferably 0.5:40 mmol / mg.

9. The method for synthesizing 4,4'-bipyridine according to claim 7, characterized in that: The dosage ratio of pyridine to the reaction solvent is 0.5:1 to 0.5:4 mmol / mL, preferably 0.5:2 to 0.5:4 mmol / mL, and more preferably 0.5:2 mmol / mL.

10. The method for synthesizing 4,4'-bipyridine according to claim 7, characterized in that: The reaction temperature is 60-100° C., preferably 80-100° C., more preferably 90-100° C.; the reaction time is 4-8 h, preferably 7-8 h.

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