Process for selectively and continuously producing 2-methylpyridine and diphenylamine from aniline

Abstract

The present invention belongs to the field of fine chemicals, and specifically relates to a method for synthesizing 2-methylpyridine from aniline, and a method for selectively and continuously producing 2-methylpyridine and diphenylamine from aniline. The method includes a step of contacting aniline with a catalyst under a hydrogen-containing atmosphere at a temperature of 100 to 400°C, the catalyst is a β-zeolite carrying a metal component, the metal component includes at least one active metal component selected from W, Mo, Ni, and Co, and the temperature of the contact reaction is controlled to 100 to 240°C to obtain a product mainly containing 2-methylpyridine, and the temperature of the contact reaction is controlled to 260 to 400°C to obtain a product mainly containing diphenylamine. The method of the present invention can easily and efficiently switch between the products of aniline and 2-methylpyridine by controlling the temperature, has mild reaction conditions, a high yield of 2-methylpyridine, and good reaction selectivity, and is expected to be industrialized.

Description

Detailed Description of the Invention

[0001] [Cross - reference to Related Applications] This application claims the benefit of Chinese Patent Application No. 202111278790.6, filed on October 31, 2021, the content of which is incorporated herein by reference.

[0002] [Technical Field] The present invention belongs to the field of fine chemicals, and specifically relates to a method for synthesizing 2 - methylpyridine from aniline, and a method for selectively and continuously producing 2 - methylpyridine and diphenylamine from aniline.

[0003] [Background Art] 2 - Methylpyridine has a molecular formula of C6H7N, is also known as α - methylpyridine and α - picoline, is a kind of pyridine base, is a colorless oily liquid with a strong unpleasant odor at room temperature, has a freezing point of - 38.9 °C and a boiling point of 129.5 °C, is highly toxic, and is soluble in acetone, ethanol, ether, water, etc. 2 - Methylpyridine is an important chemical intermediate and an important raw material for fine chemicals. It can be used in the production of long - acting sulfonamides, pesticide intermediates, feed intermediates, and can also be used in the synthesis of special resin vinylpyridine and 2 - vinylpyridine intermediates. Since the domestic consumption of 2 - methylpyridine in China is increasing by about 25% every year, the potential of the domestic market for 2 - methylpyridine in China is very large.

[0004] The production of pyridine bases in the industrial field mainly includes the coal tar separation method and the chemical synthesis method. The coal tar separation method has disadvantages such as serious pollution, few product types, high cost, low quality, high energy consumption, etc. Moreover, the production volume of the product is low and it is difficult to improve. The chemical synthesis method usually uses the ammonium-aldehyde condensation method in which aldehydes, ketones, and ammonia are reacted as raw materials to synthesize pyridine bases. However, the products of the ammonium-aldehyde condensation method include 3-methylpyridine, 2-methylpyridine, 4-methylpyridine, etc., and there are problems such as difficulty in separating the subsequent products.

[0005] CN105384683A discloses a method for separating 2-methylpyridine and 4-methylpyridine, which are by-products of the synthesis of diphenylamine from aniline. The steps are as follows. Using aniline as a raw material, it is flowed into a fixed-bed reactor filled with a molecular sieve catalyst, the temperature and pressure of the reactor are controlled, and through a condensation reaction, it is converted into diphenylamine, ammonia, and by-products such as 2-methylpyridine, 4-methylpyridine, water, acridine, 4-aminobiphenyl, etc. These mixed reaction solutions are rectified in multiple stages to obtain a low-boiling mixed fraction. This low-boiling mixed fraction is dehydrated, the mixture after dehydration is dried, and the mixed solution after drying is rectified. According to the difference in boiling points, 2-methylpyridine and 4-methylpyridine are obtained. This method is essentially a method for separating 2-methylpyridine and 4-methylpyridine, which are by-products in the conventional synthesis of diphenylamine from aniline. Therefore, in this method, since 2-methylpyridine is by-produced in the reaction process, the yield is low and mass production is impossible.

[0006] CA1190928A discloses a method for producing α-picoline from aniline, in which an aniline starting material is passed through an acidic zeolite catalyst at 200 - 650 °C in the presence of an inert gas such as nitrogen or helium to produce an α-picoline-containing product. The reaction pressure ranges from atmospheric pressure to 25000 kPa, usually 200 kPa, and the space velocity of aniline is preferably 0.2 - 5 WHSV. The acidic zeolite is preferably of the hydrogen type, contains β-zeolite, and has a silica / alumina ratio of 10 - 100, which may reach 150. Among them, in Example 1, using pure HZSM-5, at 510 °C, a pressure of 2860 kPa, ammonia being 1.5 mol% of aniline, and a nitrogen space velocity of 100 GHSV, the aniline conversion rate was 13.1% and the selectivity for α-picoline was 51.6.

[0007] "The zeolite-catalysed isomerization of aniline to a-picoline[J]. Applied catalysis A: General 172(1998)285-294" discloses a method for producing α-picoline by an aniline rearrangement reaction. This method uses a molecular sieve, preferably a Ga-MFI molecular sieve (superior to ZSM-5), as a catalyst and is carried out under the conditions of 673 K, a total pressure of 75 bar, an ammonia partial pressure of 5 - 60 bar, preferably 20 - 25 bar. Among them, the selectivity for α-picoline reaches 85% or more, but the conversion rate is only 3.7%.

[0008] 〔Summary of the Invention〕 〔Problems to be Solved by the Invention〕 The technical problem to be solved by the present invention is to solve the drawbacks of the prior art in the method of producing 2-methylpyridine by aniline rearrangement reaction, where the conversion rate of aniline is low or the selectivity of 2-methylpyridine is low. Based on the conventional apparatus for producing diphenylamine from aniline, a method for selectively producing aniline and 2-methylpyridine is provided. The method of the present invention can simply and efficiently switch the products of aniline and 2-methylpyridine by controlling the temperature. The reaction conditions are mild, the yield of 2-methylpyridine is high, the reaction selectivity is good, and industrialization can be expected.

[0009] The inventors of the present invention have discovered that the isomerization rearrangement reaction of aniline to produce 2-methylpyridine and the condensation reaction of aniline to produce diphenylamine are doubly affected by two factors: the catalyst and the reaction temperature. When using the β-zeolite catalyst of the present invention carrying at least one active metal component of W, Mo, Ni, and Co, due to the change of the catalytic active center, the reaction path of aniline can be switched between 2-methylpyridine and diphenylamine. Also, because the reaction temperature is low, it is more advantageous for the synthesis of 2-methylpyridine. Based on this finding, the present invention proposes a method for producing 2-methylpyridine and a method for selectively and continuously producing aniline and 2-methylpyridine.

[0010] 〔Means for Solving the Problem〕 In a first aspect of the present invention, there is provided a method for selectively and continuously producing 2-methylpyridine and diphenylamine from aniline, comprising the step of contacting aniline with a catalyst under a hydrogen-containing atmosphere at a temperature of 100 to 400 °C, wherein the catalyst is a β-zeolite carrying a metal component, the metal component contains at least one active metal component selected from W, Mo, Ni, and Co, and in order to obtain a product mainly composed of 2-methylpyridine, the temperature of the contacting reaction is controlled to 100 °C to 240 °C, and in order to obtain a product mainly composed of diphenylamine, the temperature of the contacting reaction is controlled to 260 °C to 400 °C.

[0011] In a second aspect of the present invention, it includes a step of bringing aniline into contact reaction with a catalyst under the conditions of an isomerization rearrangement reaction in a hydrogen-containing atmosphere. The catalyst is β-zeolite supporting a metal component, and the metal component includes at least one active metal component selected from W, Mo, Ni, and Co. The temperature of the contact reaction is 100°C to 240°C. A method for synthesizing 2-methylpyridine from aniline is provided, which is characterized by the above.

[0012] 〔Advantages of the Invention〕 When 2-methylpyridine is produced by the method of the present invention, the conversion rate of aniline is high, and moreover, the selectivity of the target product 2-methylpyridine is high. The reason is that by selecting a β-zeolite catalyst containing at least one active metal among W, Mo, Ni, and Co in a hydrogen-containing atmosphere, the reaction mechanism changes greatly, and the thermodynamic factor becomes one of the factors affecting the selectivity of 2-methylpyridine. At high temperatures, the main reaction is that two aniline molecules condense to form one diphenylamine molecule. However, when the temperature is lowered, it is considered that the main reaction becomes the production of 2-methylpyridine by the isomerization rearrangement of aniline molecules. Therefore, the method of the present invention can achieve the purpose of producing 2-methylpyridine using aniline as a raw material, and can selectively produce diphenylamine and 2-methylpyridine with existing diphenylamine process equipment.

[0013] In the prior art, usually, a large amount of ammonia gas is introduced into the synthesis of pyridine base compounds. When ammonia gas is present, the acidic sites of the catalyst are occupied, resulting in a decrease in catalyst activity. Also, due to high temperature and high pressure, the industrial application of this method is also limited. On the other hand, the method according to the present invention does not require the introduction of a large amount of ammonia gas, only the introduction of a small amount of hydrogen gas is sufficient, the reaction conditions are mild, the reaction raw material is only aniline, and high-purity 2-methylpyridine and high-purity diphenylamine can be obtained by subsequent distillation operations.

[0014] 〔Brief Description of the Drawings〕 [Fig. 1] This is a relational diagram showing the change of the product distribution with temperature of the method for selectively and continuously producing 2-methylpyridine and diphenylamine from aniline according to the present invention.

[0015] [Embodiments for Carrying out the Invention] The endpoints and any values within the ranges disclosed in this specification are not limited to this exact range or value, and should be understood to include values close to these ranges or values. In the case of numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this specification.

[0016] The method for synthesizing 2-methylpyridine from aniline according to the present invention includes a step of contacting aniline with a catalyst under the conditions of an isomerization rearrangement reaction in a hydrogen-containing atmosphere. The catalyst is a β-zeolite supporting a metal component, and the metal component includes at least one active metal component selected from W, Mo, Ni, and Co. The temperature of the contacting reaction is 100°C to 240°C.

[0017] In the present invention, by using a β-zeolite supporting at least one active metal component selected from W, Mo, Ni, and Co and controlling the reaction temperature lower than the temperature required for the normal synthesis reaction of diphenylamine from aniline in a hydrogen-containing atmosphere, a higher aniline conversion rate can be obtained, and the selectivity of 2-methylpyridine is unexpectedly improved. In addition, by adjusting the reaction temperature under the same apparatus and the same catalyst, diphenylamine and 2-methylpyridine can be selectively produced.

[0018] According to a preferred embodiment of the present invention, based on the total amount of the catalyst, in terms of metal element conversion, the content of the active metal component is 0.5 to 5 wt%, preferably 0.5 to 3 wt%.

[0019] Preferably, the metal component further contains at least one promoter metal component selected from Li, Na, K, Mg, and Ca. Based on the total amount of the catalyst, in terms of the oxidized state, the content of the promoter metal component is preferably 0 to 6.5 wt%, more preferably 0.5 to 5.5 wt%.

[0020] By adding the promoter metal component, the acid distribution on the catalyst surface and the pore structure of the catalyst are improved, and the aniline conversion rate and the selectivity of the target product are further enhanced.

[0021] Although the mechanism is not yet clear to the inventors, only by supporting the above metal component using β-zeolite under a hydrogen-containing atmosphere and adjusting the temperature, the above effects with aniline or 2-methylpyridine as the main product can be obtained, and it has been found that such effects cannot be obtained with other molecular sieves such as ZSM-5.

[0022] Preferably, the silica / alumina molar ratio of the β-zeolite is 25 to 300, preferably 60 to 220.

[0023] Preferably, the catalyst has a specific surface area of 400 to 700 m 2 / g, preferably 450 to 650 m 2 / g, a pore volume of 0.25 to 0.6 mL / g, preferably 0.4 to 0.55 mL / g, an average pore diameter of 1.5 to 5 nm, preferably 2 to 4 nm, and a particle diameter preferably less than 9 nm.

[0024] The catalyst may contain an alumina binder to obtain a shaped body of the catalyst.

[0025] According to a preferred embodiment of the present invention, based on the total amount of the catalyst, the catalyst may contain 50 to 85 wt% of zeolite, 0.5 to 5 wt% of an active metal component in terms of metal element, 0 to 6.5 wt% of a promoter metal component in terms of oxidation state, and 10 to 45 wt% of an alumina binder. Preferably, it contains 60 to 85 wt% of zeolite, 0.5 to 3 wt% of an active metal component in terms of metal element, 0.5 to 5.5 wt% of a promoter metal component in terms of oxidation state, and 15 to 34.5 wt% of an alumina binder.

[0026] The catalyst is preferably in the form of strip-shaped or spherical particles. In the case of strip-shaped particles, the cross-sectional shape may be cylindrical, clover-shaped, four-leaf clover-shaped, etc. The cross-sectional width of the strip-shaped particles is 0.5 to 3.0 mm, preferably 1.0 to 2.0 mm. In the case of spherical particles, the particle size is 0.5 to 5.0 mm, preferably 1.0 to 3.0 mm.

[0027] The above catalyst can be produced using methods known to those skilled in the art or can be commercially purchased. For example, the catalyst of the present invention can be produced by the following method. (1) Hβ zeolite is brought into contact with an aqueous nitrate solution of a promoter metal component by equal-volume impregnation. (2) The mixture obtained in step (1) is filtered, washed, and dried. (3) The modified Hβ zeolite, alumina binder, and processing aids (e.g., extrusion aids, peptizers) obtained in step (2) are thoroughly kneaded, then formed, dried, and calcined. (4) NaBH4 is added to the aqueous nitric acid solution of the carrier and the active metal component obtained in step (3), and reflux reduction is carried out, followed by filtration and vacuum drying to produce the catalyst.

[0028] The contact temperature in step (1) is 80 to 100 °C, and the time is 3 to 6 h. Step (2) is dried at 60 to 120 °C for 6 to 12 h. Step (3) is dried at 60 to 120 °C for 6 to 12 h and calcined at 450 to 550 °C for 4 to 16 h. Step (4) is reflux-reduced at 80 to 100 °C for 6 to 8 h, and then vacuum-dried at 80 to 100 °C for 6 to 12 h.

[0029] In the present invention, by using the above catalyst, a high 2-methylpyridine yield can be obtained at a low temperature in a hydrogen-containing atmosphere instead of the conventional ammonia gas atmosphere. Therefore, preferably, the catalytic reaction is carried out without introducing ammonia gas. The hydrogen-containing atmosphere refers to a hydrogen concentration of 10 to 100% by volume.

[0030] Furthermore, the temperature of the catalytic reaction is 100 to 240 °C, specifically, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 199 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, and any value within the range consisting of any two of these point values may also be used. The preferred reaction temperature is 130 to 180 °C, specifically, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, and any value within the range consisting of any two of these point values may also be used.

[0031] The method of the present invention can be carried out continuously or batchwise, but it is preferably carried out continuously. The batch operation refers to the usual kettle operation, in which raw material aniline and a catalyst are added to a reaction kettle, and the reaction is advanced under appropriate conditions to obtain the target product. The continuous operation is usually an operation in which raw material aniline is reacted through a fixed bed reactor containing a catalyst.

[0032] The inventors of the present invention have found that the optimal reaction temperatures and pressures for the continuous and batch processes are slightly different. When the batch process is employed, the temperature of the catalytic reaction is preferably 130 to 180 °C, the pressure is preferably 2 to 4 MPa, and the reaction time is preferably 4 to 8 h. Preferably, the amount of the catalyst used preferably accounts for 1 to 4 wt% of the amount of raw material aniline used. When the continuous process is employed, the temperature of the catalytic reaction is preferably 160 to 240 °C, the pressure is preferably 1.5 to 3 MPa, and the liquid weight hourly space velocity of aniline is preferably 0.5 to 3 h -1 and more preferably 1 to 1.5 h -1 is used.

[0033] The continuous operation preferably involves reacting raw material aniline in a downward feed manner through the catalyst layer of a fixed-bed reactor containing a catalyst.

[0034] The inventors of the present invention also discovered that the isomerization rearrangement reaction of aniline to produce 2-methylpyridine and the condensation reaction of aniline to produce diphenylamine are doubly affected by two factors: the catalyst and the reaction temperature. By using a metal-supported β-zeolite catalyst in the present invention, the reaction pathway of aniline can be switched between 2-methylpyridine and diphenylamine due to the change in the catalytic active center. Also, when the reaction temperature is low, it is more advantageous for the synthesis of 2-methylpyridine, and when the temperature is high, it is more advantageous for the production of diphenylamine.

[0035] Therefore, the present invention also provides a method for selectively and continuously producing 2-methylpyridine and diphenylamine from aniline, the method including the step of subjecting aniline and a catalyst to a catalytic reaction under the conditions of a temperature of 100 to 400 °C in a hydrogen-containing atmosphere, wherein the catalyst is a zeolite supporting a metal component, the metal component includes at least one active metal component selected from W, Mo, Ni, and Co, and in order to obtain a product mainly composed of 2-methylpyridine, the temperature of the catalytic reaction is controlled to be 100 to 240 °C, and in order to obtain a product mainly composed of diphenylamine, the temperature of the catalytic reaction is controlled to be 260 to 400 °C, which is characterized in that.

[0036] Preferably, when obtaining a product mainly composed of 2-methylpyridine, the catalytic reaction is at a temperature of 160 to 240 °C and a pressure of 1.5 to 3 MPa, and preferably the liquid weight hourly space velocity of the aniline is 0.5 to 3 h -1 and when obtaining a product mainly composed of diphenylamine, the catalytic reaction is at a temperature of 280 to 360 °C and a pressure of 1.5 to 3 MPa, and preferably the liquid weight hourly space velocity of the aniline is 0.3 to 1.5 h -1 is.

[0037] In the present invention, the product mainly composed of 2-methylpyridine means that the selectivity of 2-methylpyridine is 40% or more, and the product mainly composed of diphenylamine means that the selectivity of diphenylamine is 40% or more.

[0038] The catalyst has been described above and will not be elaborated here.

[0039] The conditions for synthesizing diphenylamine from aniline in the present invention are that the temperature of the catalytic reaction is preferably 280 to 360 °C, preferably the pressure is 1.5 to 3 MPa, and the liquid weight hourly space velocity of aniline is 0.3 to 1.5 h -1 , preferably 0.5 to 1 h -1 including that it is so.

[0040] In the examples and comparative examples, the calculation methods of the conversion rate of aniline, the selectivity and yield of 2-methylpyridine, and the selectivity and yield of diphenylamine are as follows.

[0041] Conversion rate of aniline = (moles of aniline in the raw material before reaction - moles of aniline in the product) / moles of aniline in the raw material before reaction × 100% Yield of 2-methylpyridine = moles of 2-methylpyridine in the product / theoretical moles of 2-methylpyridine when all aniline in the raw material before reaction is converted Selectivity of 2-methylpyridine = (moles of 2-methylpyridine in the product) / (moles of aniline in the raw material before reaction - moles of aniline in the product) × 100% Yield of diphenylamine = moles of diphenylamine in the product / theoretical moles of diphenylamine when all aniline in the raw material before reaction is converted Selectivity of diphenylamine = 2 × (moles of diphenylamine in the product) / (moles of aniline in the raw material before reaction - moles of aniline in the product) × 100% The contents of aniline, diphenylamine, and 2-methylpyridine are measured by gas chromatography.

[0042] The alumina binder used is commercially available γ-alumina, and the zeolite used is commercially available Hβ zeolite. The Hβ zeolite has a specific surface area of 620m 2 / g and a particle size of less than 9 nm.

[0043] The catalysts used in the examples and comparative examples were prepared by supporting the promoter metal component and the active metal component by the saturated impregnation method. The specific method is as follows. (1) The Hβ zeolite is brought into contact with an aqueous nitrate solution of the promoter metal component by equal-volume impregnation. (2) The mixture obtained in step (1) is filtered, washed, and dried. (3) The modified Hβ zeolite, alumina binder (for example, pseudo-boehmite), and processing aids (for example, extrusion aids, peptizers) obtained in step (2) are thoroughly kneaded, then formed, dried, and calcined. (4) NaBH4 is added to the aqueous nitric acid solution of the carrier and the active metal component obtained in step (3) and reflux-reduced, filtered, and vacuum-dried to produce a spherical catalyst with a particle size of 3 mm. The contact temperature in step (1) is 90°C, the time is 4 h, step (2) is dried at 80°C for 10 h, step (3) is dried at 80°C for 10 h and calcined at 550°C for 10 h, and step (4) is reflux-reduced at 100°C for 8 h and then vacuum-dried at 100°C for 10 h.

[0044] The characteristics of the catalysts are shown in Table 1.

[0045]

Table 1

[0046] Examples 1-8 Using a batch reactor, the reaction was carried out in a hydrogen atmosphere. The amount of catalyst used was 1 g, the amount of aniline added was 50 g, and the reaction conditions are shown in Table 2 below.

[0047] Comparative Examples 1-2 The aniline conversion reaction was carried out by the method of Example 1 except that the reaction conditions were changed as shown in Table 2 below.

[0048] Comparative Example 3 Using β-zeolite (without supported metal components) as a catalyst, the conversion reaction of aniline was carried out by the method of Example 1 except that the remaining reaction conditions were changed to those shown in Table 2 below.

[0049] Comparative Example 4 2-Methylpyridine was produced from aniline by the method described in Example 1 of CA1190928A, that is, using pure HZSM-5, at 510 °C, a pressure of 2.9 MPa, and a molar ratio of raw material aniline to ammonia of 1:8, the weight hourly space velocity was 1.0 h -1 Under these conditions, aniline was converted to 2-methylpyridine.

[0050] [Table 2]

[0051] Examples 9 - 16 A fixed-bed reactor was selected, and the raw material aniline was passed through the catalyst layer in a downward feeding manner. Under a hydrogen atmosphere, first, the reaction was carried out for 48 hours under conditions suitable for the production of 2-methylpyridine, and then, at a heating rate of 30 °C / hour, the reaction conditions were switched to those suitable for the production of diphenylamine, and the reaction was continued for 48 hours. The product distribution was measured and shown in Table 3 below.

[0052] [Table 3]

[0053] Example 17 By the method of Example 9, diphenylamine and 2-methylpyridine were produced from raw material aniline, and the influence of temperature on the product distribution was investigated. After each sampling, the temperature was raised to the next temperature at a heating rate of 30 °C / hour. The distribution of the products changed with temperature, and the relationship diagram is shown in Figure 1.

[0054] From the results of Table 2 and Figure 1, it was found that the method for producing 2-methylpyridine according to the present invention can obtain a higher aniline conversion rate and 2-methylpyridine selectivity at a lower reaction temperature.

[0055] From the results in Table 3 and Figure 1, the method for selectively and continuously producing diphenylamine and 2-methylpyridine according to the present invention can easily obtain diphenylamine and 2-methylpyridine, which are different target products, on the same apparatus by adjusting process parameters such as reaction temperature and pressure.

Brief Description of the Drawings

[0056]

Figure 1

Claims

1. A method for selectively and continuously producing 2-methylpyridine and diphenylamine from aniline, comprising the step of subjecting aniline and a catalyst to a catalytic reaction under a hydrogen-containing atmosphere at a temperature of 100 to 400 °C, wherein the catalyst is β-zeolite supporting a metal component, the metal component contains at least one active metal component selected from W, Mo, Ni, and Co, and in order to obtain a product mainly composed of 2-methylpyridine, the temperature of the catalytic reaction is controlled to 100 to 240 °C, and in order to obtain a product mainly composed of diphenylamine, the temperature of the catalytic reaction is controlled to 260 to 400 °C. This is a characteristic method.

2. The method according to claim 1, wherein, based on the total amount of the catalyst, in terms of metal element conversion, the content of the active metal component is 0.5 to 5 wt%.

3. The method according to claim 2, wherein, based on the total amount of the catalyst, in terms of metal element conversion, the content of the active metal component is 0.5 to 3 wt%.

4. The method according to claim 1, wherein the metal component further contains at least one promoter metal component selected from Li, Na, K, Mg, and Ca, and based on the total amount of the catalyst, in terms of oxidation state conversion, the content of the promoter metal component is 0 to 6.5 wt%.

5. The method according to claim 4, wherein, based on the total amount of the catalyst, in terms of oxidation state conversion, the content of the promoter metal component is 0.5 to 5.5 wt%.

6. The catalyst further contains an alumina binder. Based on the total amount of the catalyst, the catalyst contains 50 to 85 wt% of β-zeolite, 0.5 to 5 wt% of an active metal component in terms of metal element conversion, 0 to 6.5 wt% of a promoter metal component in terms of oxidation state conversion, and 10 to 45 wt% of an alumina binder. The method according to any one of claims 1 to 5.

7. The method according to claim 6, wherein, based on the total amount of the catalyst, the catalyst contains 60 to 85 wt% of β-zeolite, 0.5 to 3 wt% of an active metal component in terms of metal element conversion, 0.5 to 5.5 wt% of a promoter metal component in terms of oxidation state conversion, and 15 to 34.5 wt% of an alumina binder.

8. The method according to any one of claims 1 to 5, wherein the pressure of the catalytic reaction is 1.5 to 4 MPa, and the catalytic reaction is carried out under a hydrogen atmosphere.

9. The method according to any one of claims 1 to 5, wherein the catalytic reaction is carried out without introducing ammonia gas.

10. When obtaining a product mainly composed of 2-methylpyridine, the catalytic reaction is carried out at a temperature of 160 to 240 °C and a pressure of 1.5 to 3 MPa, and the liquid weight space velocity of the aniline is 0.5 to 3 h －１ and, or When obtaining a product mainly composed of diphenylamine, the catalytic reaction is carried out at a temperature of 280 to 360 ° C and a pressure of 1.5 to 3 MPa, and the liquid weight hourly space velocity of the aniline is 0.3 to 1.5 h －１ The method according to any one of claims 1 to 5, wherein the method is as described above.

11. The method according to claim 10, wherein the aniline is reacted in a fixed bed reactor containing the catalyst.

12. The method according to claim 11, wherein the aniline is fed to the fixed bed reactor in a downward feeding manner and passes through the catalyst bed.

13. A method for synthesizing 2-methylpyridine from aniline, comprising the step of contacting aniline with a catalyst under the conditions of an isomerization rearrangement reaction in a hydrogen-containing atmosphere, wherein the catalyst is β-zeolite supporting a metal component, and the metal component comprises at least one active metal component selected from W, Mo, Ni, and Co, and the temperature of the contacting reaction is 100°C to 240°C.

14. The method according to claim 13, wherein, based on the total amount of the catalyst, in terms of metal element conversion, the content of the active metal component is 0.5 to 5 wt%.

15. The method according to claim 14, wherein, based on the total amount of the catalyst, in terms of metal element conversion, the content of the active metal component is 0.5 to 3 wt%.

16. The method according to claim 13, wherein the metal component further comprises at least one promoter metal component selected from Li, Na, K, Mg, and Ca, and based on the total amount of the catalyst, in terms of oxidation state conversion, the content of the promoter metal component is 0 to 6.5 wt%.

17. The catalyst further contains an alumina binder, and based on the total amount of the catalyst, the catalyst contains 50 to 85 wt% of β-zeolite, 0.5 to 5 wt% of an active metal component in terms of metal element conversion, 0 to 6.5 wt% of a promoter metal in terms of oxidation state conversion, and 10 to 45 wt% of an alumina binder. The method according to any one of claims 13 to 16.

18. The method according to claim 17, wherein, based on the total amount of the catalyst, the catalyst contains 60 to 85 wt% of β-zeolite, 0.5 to 3 wt% of an active metal component in terms of reduction state conversion, 0.5 to 5.5 wt% of a promoter metal component in terms of oxidation state conversion, and 15 to 34.5 wt% of an alumina binder.

19. The method according to any one of claims 13 to 16, wherein the contacting reaction is carried out without introducing ammonia gas.

20. The contacting reaction is carried out intermittently, the contacting reaction is at a temperature of 130 to 180°C, a pressure of 2 to 4 MPa, and a reaction time of 4 h to 8 h, and the amount of the catalyst used accounts for 1 to 4 wt% of the amount of raw material aniline used, or The contact reaction is carried out continuously, and the contact reaction is at a temperature of 160 to 240°C and a pressure of 1.5 to 3 MPa, and the liquid weight space velocity of the aniline is 0.5 to 3 h －１ The method according to any one of claims 13 to 16, wherein the method is as described above.

21. The method according to claim 20, wherein the raw material aniline is reacted in a fixed-bed reactor containing the catalyst, and the raw material aniline enters the fixed-bed reactor in a downward feeding manner and passes through the catalyst layer.

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