Preparation method of catalyst for synthesizing 2-methylpyridine

Abstract

The invention discloses a method for preparing a catalyst for synthesizing 2-methylpyridine, comprising the following steps: preparing a catalyst containing Fe 3+ , Cu 2+ 、Ni2 + The three hydrochloride solutions were mixed and the HZMS‑5 molecular sieve was mixed with Fe 3+ , Cu 2+ 、Ni 2+ The invention relates to a method for preparing 2-methylpyridine by reacting acetaldehyde and ammonia as raw materials at 300°C-450°C and 0.5MPa-0.8MPa under the action of the catalyst, and the method has the advantages of simple preparation method, low cost, high-efficiency synthesis of 2-methylpyridine under mild reaction conditions, and more economical and environmentally friendly. The invention solves the problems of high raw material price, use of precious metals, dangerous reaction conditions, etc. in the prior art, has high yield of 2-methylpyridine, good selectivity and good industrial application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a method for preparing a catalyst for synthesizing 2-methylpyridine. Background Art

[0002] Pyridine base compounds have important application value in the field of fine chemicals, and their application range is wide, including medicine, pesticides, feed additives, daily chemical products and food additives. According to the different substituents, pyridine base compounds can be classified into different types such as alkyl pyridine, halogenated pyridine, aminopyridine, etc. Among these compounds, alkyl pyridine, as a key chemical raw material, especially 2-methylpyridine, plays a vital role in the synthesis of styrene-butadiene rubber and pyridine acid pesticides. 2-methylpyridine can be converted into 2-vinylpyridine through catalytic reaction, and then polymerize with butadiene and styrene to produce styrene-butadiene rubber. Due to its excellent performance, this rubber is widely used in the production and manufacturing of automobile tires. In addition, 2-methylpyridine is oxidized and ammoniated to produce 2-cyanopyridine, which is further chlorinated and hydrolyzed to produce chloropyridine acid pesticides, which occupy an important position in the pesticide market.

[0003] The domestic method for producing 2-methylpyridine mainly includes: separating crude pyridine obtained from coal tar, performing atmospheric distillation in a packed tower, removing the moisture in pyridine by azeotropic distillation of pure benzene and water, and intercepting the fraction to obtain the 2-methylpyridine product, but the crude pyridine content in coal tar is low and the composition is complicated, and the energy consumption is huge and the cost is high when separating 2-methylpyridine, so this method is less used; there is also a method of using acetylene and acetonitrile as raw materials, and cyclizing to generate 2-methylpyridine under the action of bis(cyclopentadienyl) nickel catalyst. Under laboratory conditions, the yield of this reaction can reach more than 90%, but in the actual production process, due to problems in the preparation and use of the catalyst, and the unreacted raw material recovery is not timely enough, which may cause the device stability to be poor, and then affect the overall yield; there is also a method of producing 2-methylpyridine by ethanol catalytic ammoniation, but the total yield of pyridine base in this method is low, and the catalyst is easily reduced and deactivated, and needs to be re-oxidized before it can be used again.

[0004] The Chinese patent with publication number CN113304747A uses acetone and acrylonitrile as raw materials, and converts the raw materials into 2-methylpyridine in one pot with the help of palladium catalyst under specific temperature and pressure conditions; the reaction operation process of this method is simple and the selectivity of the target product is high. However, the raw material acrylonitrile is prone to self-polymerization, which causes waste and pipeline blockage, and the catalyst uses precious metal palladium, which has poor economic benefits and is difficult to apply on a large scale.

[0005] The Chinese patent application with publication number CN115504929A uses ethanol and ammonia as raw materials to synthesize 2-methylpyridine under the action of a catalyst of an iron-cobalt active component and a rare earth additive. This method improves the stability and activity of the catalyst, solves the problem of difficult product separation and safety and environmental protection of raw materials, but the use of rare earth elements increases costs, and ethanol as a reaction raw material needs to be further oxidized before the reaction occurs, resulting in a low yield of 2-methylpyridine.

[0006] The Chinese patent application with publication number CN116063225A uses aniline as a raw material. In the presence of a catalyst, aniline undergoes an isomerization rearrangement reaction, and the reaction product is separated to obtain 2-methylpyridine. The reaction conditions of this method are relatively mild, and the yield of 2-methylpyridine is relatively high. However, the reaction must be carried out in a hydrogen atmosphere, which is highly dangerous, and the by-product diphenylamine is inevitably generated. Since aniline is used as a raw material, the price is high and the economic benefits are poor.

[0007] The Chinese patent with publication number CN103252254A has designed a catalyst, using ZSM-5 molecular sieve as a carrier, modified by three metals of chromium, lanthanum and platinum, catalyzing the reaction of acetaldehyde and ammonia to generate 2-methylpyridine and 4-methylpyridine. The catalyst has a higher yield for 2-methylpyridine and 4-methylpyridine, and can maintain stability and selectivity for a long time, and the preparation method is simple and easy. However, the method uses precious metal platinum, which is costly, and the reaction product is a mixture of 2-methylpyridine and 4-methylpyridine. Subsequent separation also further increases the cost, and the use of aqua regia to dissolve metals is more dangerous. Summary of the invention

[0008] The invention aims to provide a method for preparing a catalyst for synthesizing 2-methylpyridine. The catalyst uses HZMS-5 molecular sieve as a substrate, introduces iron, copper and nickel metal ions as active components, and improves the conversion rate and selectivity of synthesizing 2-methylpyridine by reacting acetaldehyde and ammonia. The catalyst preparation method is simple, low in cost, excellent in stability, economical and environmentally friendly, mild in reaction conditions, high in 2-methylpyridine yield and good in selectivity. The invention solves the problems of high raw material prices, use of precious metals, dangerous reaction conditions and the like existing in the above technical background.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] The preparation method of the catalyst for synthesizing 2-methylpyridine comprises the following steps:

[0011] S1: Add hydrochloric acid to the solids of ferric oxide, copper oxide, and nickel oxide to prepare a solution containing Fe3+, Cu2+, Ni 2 + hydrochloride solution, mixing the three hydrochloride solutions to obtain a mixed solution;

[0012] S2: contacting the HZMS-5 molecular sieve with the mixed solution to obtain a mixture, adjusting the pH of the mixture with aqueous ammonia, stirring the mixture evenly in a constant temperature oscillator, and separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation;

[0013] S3: After washing with deionized water and ethanol, the precipitate is dried in a nitrogen atmosphere, the dried solid material is ground, a binder is added, and pressed into a shape, and the formed solid is calcined in a muffle furnace at a programmed temperature to form a granular catalyst;

[0014] S4: After the vaporized acetaldehyde and ammonia are transported to the premixing section of the multi-tubular reactor through a metering system, they enter the main reaction zone containing the granular catalyst, and the reactants react in the catalyst bed to generate 2-methylpyridine, which is then collected through a condensation system to obtain 2-methylpyridine.

[0015] Furthermore, the Fe 3+ :Cu 2+ :N i 2+ The molar ratio is: 1-4:1-4:1-4.

[0016] Furthermore, the concentrations of Fe3+, Cu2+ and Ni2+ in the three hydrochloride solutions are 0.05 mol / L-0.15 mol / L.

[0017] Furthermore, the mixture has a pH of 7-11 and is stirred evenly at 60° C. in a constant temperature oscillator for 24 hours.

[0018] Furthermore, the silicon-aluminum ratio of the HZMS-5 molecular sieve is 30-200.

[0019] Furthermore, the drying conditions under the nitrogen atmosphere are: drying the washed precipitate under a nitrogen atmosphere at 80° C.-120° C. for 6 hours, and then further drying under a nitrogen atmosphere at 180° C.-240° C. for 4 hours.

[0020] Furthermore, the binder is pseudo-boehmite, and the binder accounts for 1%-5% of the total mass of the catalyst.

[0021] Furthermore, the programmed temperature rising method for high temperature roasting in the muffle furnace is: rising to 250°C-300°C at a rate of 2°C / min and maintaining for 2 hours, and then rising to 450°C-550°C at the same rate and maintaining for 4 hours.

[0022] Furthermore, the molar ratio of ammonia to acetaldehyde is 2-6:1.

[0023] Furthermore, the vaporized acetaldehyde enters the reaction tube through an outer pipe, and ammonia is injected through an inner sleeve. The reactor temperature is 300° C.-450° C., and the reaction pressure is 0.5 MPa-0.8 MPa.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The catalyst uses HZMS-5 molecular sieve as a substrate and introduces iron, copper and nickel metal ions as active components to improve the conversion rate and selectivity of synthesizing 2-methylpyridine by reacting acetaldehyde and ammonia; it solves the problems of high raw material prices, the use of precious metals, and dangerous reaction conditions. The catalyst preparation method is simple, low-cost, and has excellent stability. It is economical and environmentally friendly, the reaction conditions are mild, and the yield of 2-methylpyridine is high and the selectivity is good. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In order to solve the technical problems of the synthesis method of 2-methylpyridine in the prior art, which has high raw material prices, the use of precious metals, and dangerous reaction conditions, this embodiment provides the following technical solutions:

[0028] Example 1: Hydrochloric acid was added to ferric oxide, copper oxide and nickel oxide to prepare a solution containing Fe3+, Cu2+ and Ni 2 + hydrochloride solution, the concentration of the three hydrochloride solutions is 0.1 mol / L, and the total mass is 200 g; according to the molar ratio of metal ions Fe 3+ :Cu 2+ :N i 2+ =1:1:1 mixed solution, adding 20g of HZMS-5 molecular sieve with a silicon-aluminum ratio of 80 to contact the mixed solution to obtain a mixture, adjusting the pH of the mixture to 8 with ammonia water, and then stirring it evenly at 60°C in a constant temperature oscillator for 24 hours; separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation, washing it with deionized water and ethanol; drying the washed precipitate under a nitrogen atmosphere at 100°C for 6 hours, and then further drying it under a nitrogen atmosphere at 200°C for 4 hours; grinding the dried solid material in a planetary ball mill, adding 1g of pseudo-boehmite as a binder, pressing and molding, and subjecting the molded solid to programmed temperature calcination in a muffle furnace, raising the temperature to 300°C at a rate of 2°C / min and holding it for 2 hours, and then raising the temperature to 500°C at the same rate and holding it for 4 hours to prepare a finished catalyst.

[0029] 10 g of catalyst was loaded into a tubular reactor, 20 g of acetaldehyde was taken, acetaldehyde was added to vaporize at 60° C., the acetaldehyde injection rate was controlled by a liquid mass flowmeter, the vaporized acetaldehyde entered the reaction tube through an outer pipe, and ammonia was introduced from the inner sleeve, the molar ratio of ammonia to acetaldehyde was 5:1, ammonia and vaporized acetaldehyde were preliminarily mixed in a premixing section, and entered a tubular reactor filled with the prepared granular catalyst, acetaldehyde and ammonia were fully mixed and reacted in the catalyst bed at 350° C. and 0.6 MPa to generate 2-methylpyridine, which was collected by a condensation system and the yield of 2-methylpyridine was 68.6%.

[0030] Example 2: Hydrochloric acid was added to ferric oxide, copper oxide and nickel oxide to prepare a solution containing Fe3+, Cu2+ and Ni 2 + hydrochloride solution, the concentration of the three hydrochloride solutions is 0.1 mol / L, and the total mass is 200 g; according to the molar ratio of metal ions Fe 3+ :Cu 2+ :N i 2+ =2:1:1 ratio mixed solution, adding 20g HZMS-5 molecular sieve with a silicon-aluminum ratio of 80 to contact the mixed solution to obtain a mixture, adjusting the pH of the mixture to 8 with ammonia water, and then stirring evenly at 60°C in a constant temperature oscillator for 24 hours; separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation, washing with deionized water and ethanol; drying the washed precipitate under nitrogen at 100°C for 6 hours, and then further drying it under a nitrogen atmosphere at 200°C for 4 hours; grinding the dried solid material in a planetary ball mill, adding 1g of pseudo-boehmite as a binder, pressing and molding, and subjecting the molded solid to programmed temperature calcination in a muffle furnace, increasing the temperature to 300°C at a rate of 2°C / min and maintaining for 2 hours, and then increasing the temperature to 500°C at the same rate and maintaining for 4 hours to obtain a finished catalyst.

[0031] 10 g of catalyst was loaded into a tubular reactor, 20 g of acetaldehyde was taken, and the acetaldehyde was added to a vaporization chamber at 60° C. for vaporization. A liquid mass flowmeter was used to control the acetaldehyde injection rate. The vaporized acetaldehyde entered the reaction tube through an outer pipe, and ammonia was introduced from an inner sleeve. The molar ratio of ammonia to acetaldehyde was 5:1. The ammonia and the vaporized acetaldehyde were preliminarily mixed in a premixing section and entered a tubular reactor containing the prepared granular catalyst. Under the conditions of 350° C. and 0.6 MPa, the acetaldehyde and ammonia were fully mixed and reacted in the catalyst bed to generate 2-methylpyridine, which was collected by a condensation system with a yield of 72.6%.

[0032] Example 3: Hydrochloric acid was added to ferric oxide, copper oxide and nickel oxide to prepare a solution containing Fe3+, Cu2+ and Ni 2+ hydrochloride solution, the concentrations are 0.1 mol / L, 0.1 mol / L, 0.1 mol / L, and the total mass is 200 g; according to the metal ion molar ratio Fe 3+ :Cu 2+ :N i 2+ =1:2:1 ratio mixed solution, adding 20g HZMS-5 molecular sieve with a silicon-aluminum ratio of 80 to contact the mixed solution to obtain a mixture, adjusting the pH of the mixture to 8 with ammonia water, and then stirring evenly at 60°C in a constant temperature oscillator for 24 hours; separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation, washing with deionized water and ethanol; drying the washed precipitate under nitrogen at 100°C for 6 hours, and then further drying it under a nitrogen atmosphere at 200°C for 4 hours; grinding the dried solid material in a planetary ball mill, adding 1g of pseudo-boehmite as a binder, pressing and molding, and performing programmed temperature calcination on the molded solid in a muffle furnace, heating to 300°C at a rate of 2°C / min and maintaining for 2 hours, and then heating to 500°C at the same rate and maintaining for 4 hours to prepare a finished catalyst.

[0033] 10 g of catalyst was loaded into a tubular reactor, 20 g of acetaldehyde was taken, and the acetaldehyde was added to a vaporization chamber at 60° C. for vaporization. A liquid mass flowmeter was used to control the acetaldehyde injection rate. The vaporized acetaldehyde entered the reaction tube through an outer pipe, and ammonia was introduced from an inner sleeve. The molar ratio of ammonia to acetaldehyde was 5:1. The ammonia and the vaporized acetaldehyde were preliminarily mixed in a premixing section and entered a tubular reactor containing the prepared granular catalyst. Under the conditions of 350° C. and 0.6 MPa, the acetaldehyde and ammonia were fully mixed and reacted in the catalyst bed to generate 2-methylpyridine, which was collected by a condensation system and the yield of 2-methylpyridine was 65.9%.

[0034] Example 4: Hydrochloric acid was added to ferric oxide, copper oxide and nickel oxide to prepare a solution containing Fe3+, Cu2+ and Ni 2 + hydrochloride solution, the concentration of the three hydrochloride solutions is 0.1 mol / L, and the total mass is 200 g; according to the molar ratio of metal ions Fe 3+ :Cu 2+ :N i 2+=1:1:2 ratio of the mixed solution, adding 20g of HZMS-5 molecular sieve with a silicon-aluminum ratio of 80 to contact the mixed solution to obtain a mixture, using ammonia water to adjust the pH of the mixture to 8, and then stirring it evenly at 60°C in a constant temperature oscillator for 24 hours; separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation, washing it with deionized water and ethanol; drying the washed precipitate under nitrogen at 100°C for 6 hours, and then further drying it under a nitrogen atmosphere at 200°C for 4 hours; grinding the dried solid material in a planetary ball mill, adding 1g of pseudo-boehmite as a binder, pressing and molding, and performing programmed temperature calcination on the molded solid in a muffle furnace, raising the temperature to 300°C at a rate of 2°C / min and holding it for 2 hours, and then raising the temperature to 500°C at the same rate and holding it for 4 hours to prepare a finished catalyst.

[0035] 10 g of catalyst was loaded into a tubular reactor, 20 g of acetaldehyde was taken, and the acetaldehyde was added to a vaporization chamber at 60° C. for vaporization. A liquid mass flowmeter was used to control the acetaldehyde injection rate. The vaporized acetaldehyde entered the reaction tube through an outer pipe, and ammonia was introduced from an inner sleeve. The molar ratio of ammonia to acetaldehyde was 5:1. The ammonia and the vaporized acetaldehyde were preliminarily mixed in a premixing section and entered a tubular reactor containing the prepared granular catalyst. Under the conditions of 350° C. and 0.6 MPa, the acetaldehyde and ammonia were fully mixed and reacted in the catalyst bed to generate 2-methylpyridine, which was collected by a condensation system and the yield of 2-methylpyridine was 70.7%.

[0036] Example 5: Hydrochloric acid was added to ferric oxide, copper oxide and nickel oxide to prepare a solution containing Fe3+, Cu2+ and Ni 2 + hydrochloride solution, the concentration of the three hydrochloride solutions is 0.1 mol / L, and the total mass is 200 g; according to the molar ratio of metal ions Fe 3+ :Cu 2+ :N i 2+ =2:1:1 ratio mixed solution, adding 20g HZMS-5 molecular sieve with a silicon-aluminum ratio of 40 to contact the mixed solution to obtain a mixture, adjusting the pH of the mixture to 8 with ammonia water, and then stirring evenly at 60°C in a constant temperature oscillator for 24 hours; separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation, washing with deionized water and ethanol; drying the washed precipitate under nitrogen at 100°C for 6 hours, and then further drying it under a nitrogen atmosphere at 200°C for 4 hours; grinding the dried solid material in a planetary ball mill, adding 1g of pseudo-boehmite as a binder, pressing and molding, and performing programmed temperature rising roasting on the molded solid in a muffle furnace, raising the temperature to 300°C at a rate of 2°C / min and maintaining for 2 hours, and then raising the temperature to 500°C at the same rate and maintaining for 4 hours to prepare a finished catalyst.

[0037] 10 g of catalyst was loaded into a tubular reactor, 20 g of acetaldehyde was taken, and the acetaldehyde was added to a vaporization chamber at 60° C. for vaporization. A liquid mass flowmeter was used to control the acetaldehyde injection rate. The vaporized acetaldehyde entered the reaction tube through an outer pipe, and ammonia was introduced from an inner sleeve. The molar ratio of ammonia to acetaldehyde was 5:1. The ammonia and the vaporized acetaldehyde were preliminarily mixed in a premixing section and entered a tubular reactor containing the prepared granular catalyst. The acetaldehyde and ammonia were fully mixed and reacted in the catalyst bed at 350° C. and 0.6 MPa to generate 2-methylpyridine, which was collected by a condensation system with a yield of 78.5%.

[0038] Example 6: Hydrochloric acid was added to ferric oxide, copper oxide and nickel oxide to prepare a solution containing Fe3+, Cu2+ and Ni 2 + hydrochloride solution, the concentration of the three hydrochloride solutions is 0.1 mol / L, and the total mass is 200 g; according to the molar ratio of metal ions Fe 3+ :Cu 2+ :N i 2+ =2:1:1 ratio mixed solution, adding 20g HZMS-5 molecular sieve with a silicon-aluminum ratio of 160 to contact the mixed solution to obtain a mixture, adjusting the pH of the mixture to 8 with ammonia water, and then stirring evenly at 60°C in a constant temperature oscillator for 24 hours; separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation, washing with deionized water and ethanol; drying the washed precipitate under nitrogen at 100°C for 6 hours, and then further drying it under a nitrogen atmosphere at 200°C for 4 hours; grinding the dried solid material in a planetary ball mill, adding 1g of pseudo-boehmite as a binder, pressing and molding, and performing programmed temperature rising roasting on the molded solid in a muffle furnace, raising the temperature to 300°C at a rate of 2°C / min and holding for 2 hours, and then raising the temperature to 500°C at the same rate and holding for 4 hours to prepare a finished catalyst.

[0039] 10 g of catalyst was loaded into a tubular reactor, 20 g of acetaldehyde was taken, and the acetaldehyde was added to a vaporization chamber at 60° C. for vaporization. A liquid mass flowmeter was used to control the acetaldehyde injection rate. The vaporized acetaldehyde entered the reaction tube through an outer pipe, and ammonia was introduced from the inner sleeve. The molar ratio of ammonia to acetaldehyde was 5:1. The ammonia and the vaporized acetaldehyde were preliminarily mixed in a premixing section and entered a tubular reactor containing the prepared granular catalyst. Under the conditions of 350° C. and 0.6 MPa, the acetaldehyde and ammonia were fully mixed and reacted in the catalyst bed to generate 2-methylpyridine, which was collected by a condensation system and the yield of 2-methylpyridine was 70.1%.

[0040] 2-methylpyridine was synthesized using acetaldehyde and ammonia as raw materials in the presence of a catalyst containing iron ions, copper ions and nickel ions. The yields of 2-methylpyridine in various examples are summarized in Table 1:

[0041] Table 1: 2-methylpyridine yield

[0042]

[0043] As shown in Table 1, when the concentration of metal hydrochloride solution, the total mass of metal hydrochloride solution, the silicon-aluminum ratio of HZMS-5 molecular sieve, the mass of pseudo-boehmite, the mass of catalyst, the mass of acetaldehyde, and the molar ratio of ammonia to acetaldehyde are all the same, the yield of 2-methylpyridine is affected by Fe 3+ :Cu 2+ :Ni 2+ The molar ratio affects the Fe 3+ :Cu 2+ :N i 2+ =2:1:1, the yield of 2-methylpyridine is the highest, and the yield of 2-methylpyridine is 72.6%.

[0044] It can be seen from Table 1 that when the concentration of metal hydrochloride solution, the total mass of metal hydrochloride solution, and the molar ratio of metal ions Fe 3 + :Cu 2+ :N i 2+ When the mass of pseudo-boehmite, the mass of catalyst, the mass of acetaldehyde and the molar ratio of ammonia to acetaldehyde are the same, the yield of 2-methylpyridine is affected by the silicon-aluminum ratio of HZMS-5 molecular sieve. When the silicon-aluminum ratio of HZMS-5 molecular sieve is 40, the yield of 2-methylpyridine is the highest, and the yield of 2-methylpyridine is 78.5%.

[0045] In summary, the present invention is used for efficiently synthesizing 2-methylpyridine. The catalyst is based on the HZMS-5 molecular sieve, and metal ions of iron, copper and nickel are introduced as active components, so that the conversion rate and selectivity of acetaldehyde and ammonia to generate 2-methylpyridine are significantly improved. The catalyst preparation method is simple, low in cost, and excellent in stability. High-efficiency 2-methylpyridine synthesis can be achieved under mild reaction conditions, so that the entire synthesis process is more economical and environmentally friendly.

[0046] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for synthesizing 2-methylpyridine, characterized in that: The steps include: S1: Add hydrochloric acid to the solids of ferric oxide, copper oxide, and nickel oxide to prepare a solution containing Fe3+, Cu2+, Ni 2 + hydrochloride solution, mixing the three hydrochloride solutions to obtain a mixed solution; S2: contacting the HZMS-5 molecular sieve with the mixed solution to obtain a mixture, adjusting the pH of the mixture with aqueous ammonia, stirring the mixture evenly in a constant temperature oscillator, and separating the HZMS-5 molecular sieve precipitate containing metal ions by centrifugation; S3: After washing with deionized water and ethanol, the precipitate is dried in a nitrogen atmosphere, the dried solid material is ground, a binder is added, and pressed into a shape, and the formed solid is calcined in a muffle furnace at a programmed temperature to form a granular catalyst; S4: After the vaporized acetaldehyde and ammonia are transported to the premixing section of the multi-tubular reactor through a metering system, they enter the main reaction zone containing the granular catalyst, and the reactants react in the catalyst bed to generate 2-methylpyridine, which is then collected through a condensation system to obtain 2-methylpyridine.

2. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The mixed solution contains Fe 3+ :Cu 2+ :Ni 2+ The molar ratio is: 1-4:1-4:1-4.

3. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The three hydrochloride solutions contain Fe3+, Cu2+, and Ni 2 +The concentration is 0.05mo / L-0.15mo / L.

4. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The mixture has a pH of 7-11 and is stirred evenly in a thermostatic oscillator at 60° C. for 24 hours.

5. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The silicon-aluminum ratio in the HZMS-5 molecular sieve is 30-200.

6. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The drying conditions under nitrogen atmosphere are as follows: the washed precipitate is dried at 80°C-120°C under nitrogen atmosphere for 6 hours, and then further dried at 180°C-240°C under nitrogen atmosphere for 4 hours.

7. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The binder is pseudo-boehmite, and the binder accounts for 1%-5% of the total mass of the catalyst.

8. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The programmed temperature rising method for high temperature calcination in the muffle furnace is: rising to 250°C-300°C at a rate of 2°C / min and maintaining for 2 hours, and then rising to 450°C-550°C at the same rate and maintaining for 4 hours.

9. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The molar ratio of ammonia to acetaldehyde is 2-6:

1.

10. The method for preparing a catalyst for synthesizing 2-methylpyridine according to claim 1, characterized in that: The vaporized acetaldehyde enters the reaction tube through the outer pipe, and ammonia is injected through the inner sleeve. The reactor temperature is 300℃-450℃, and the reaction pressure is 0.5MPa-0.8MPa.

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