A method for the production of methylamine

Abstract

The present application belongs to the technical field of methylamine synthesis, and particularly relates to a methylamine production and synthesis method. In the production and synthesis of methylamine, the azeotrope and mixed amine in the production process are recycled, the raw material utilization rate is significantly improved, the waste discharge is reduced, it is green and environment-friendly, the energy utilization rate is improved by adopting staged heating before synthesis, and the production energy consumption is reduced. Through the unique preparation process, the prepared catalyst has high selectivity for the synthesis of methylamine, the production of by-products can be significantly reduced, the yield and purity of the product are improved, and the catalyst has good stability. The Ar / H2 plasma treatment enhances the carbon deposition resistance of the catalyst, the catalyst still has high activity after 24h of continuous operation, and the service life of the catalyst is long.

Description

Technical Field

[0001] This invention belongs to the field of methylamine synthesis technology, and specifically relates to a method for the production and synthesis of methylamine. Background Technology

[0002] Methylamine (including monomethylamine, dimethylamine, and trimethylamine) is an important chemical raw material, widely used in pesticides, pharmaceuticals, dyes, rubber, fuels, surfactants, and other fields. Among them, dimethylamine is used the most, mainly for the production of N,N-dimethylformamide (DMF).

[0003] Traditional methylamine synthesis often uses single-pass feedstocks, failing to fully utilize byproducts and unconverted feedstocks, resulting in complex and inefficient cycles. Production processes typically employ multi-tower distillation separation (such as deammoniation, extraction, and dehydration towers), leading to complex processes and high equipment investment. Traditional catalysts suffer from poor selectivity and insufficient stability, easily deactivating due to carbon buildup or high temperatures. The disposal of spent catalysts (HW50 hazardous waste) increases environmental costs. Furthermore, traditional gas-phase catalytic reactions require high-temperature and high-pressure conditions (reaction temperature 300-500℃, pressure 2.0-5.0 MPaG), resulting in high energy consumption, rudimentary reaction conditions, difficulty in controlling pressure and temperature, and complex wastewater and tail gas treatment.

[0004] In recent years, although research has attempted to improve the synthesis process, such as by using novel catalysts and optimizing reaction conditions, the problems of high energy consumption, high pollution, and low efficiency have not been fundamentally solved. Therefore, developing an environmentally friendly, highly efficient, and energy-saving methylamine synthesis process is of great significance for promoting the sustainable development of related industries. Summary of the Invention

[0005] The purpose of this invention is to address the existing problems by providing a method for the synthesis of methylamine.

[0006] This invention is achieved through the following technical solution:

[0007] The present invention has the following advantages over the prior art:

[0008] A method for synthesizing methylamine includes the following steps:

[0009] S1. Methanol, liquid ammonia and azeotropic mixtures and mixed amines produced during the production of methylamine are pressurized by pumps and then mixed. After passing through multiple heat exchange, gasification and electric heating to 380~450℃, they enter the synthesis tower.

[0010] S2. A gas-phase amination reaction is carried out in the catalyst layer inside the synthesis tower;

[0011] S3. The crude amine gas generated by the gas amination reaction is condensed by heat, and then the products are separated and the tail gas and wastewater are treated.

[0012] Furthermore, in step S1, methanol is used as the reference raw material, the molar ratio of methanol to ammonia is 1:(1.5~4), the mass of azeotrope added accounts for 5~15% of the total feed, and the mass of mixed amine added accounts for 10~20% of the total feed.

[0013] Further, the specific operation of step S1 is as follows: methanol, liquid ammonia and azeotrope and mixed amine produced in the production process of methylamine are respectively pumped to 2~5MPaG and then mixed. The resulting raw material mixture is then heated to 120~130℃ through a low temperature heat exchanger, then vaporized to 140℃ through a start-up vaporizer, then heated to 320℃ through a three-series high temperature heat exchanger with the reaction gas, and finally heated to 380~450℃ by an electric heating furnace before entering the synthesis tower.

[0014] Furthermore, the catalyst layer described in step S2 is filled with a catalyst, and the preparation of the catalyst includes the following steps:

[0015] (1) Mix Al(NO3)3·9H2O with tetraethyl orthosilicate and phosphoric acid according to n(Al 3+ ):n(Si):n(PO4 3- The mixture of Al(NO3)3 and PVP was dissolved in a mixed solvent of deionized water and anhydrous ethanol at a molar ratio of 5:2:1. Then, polyvinylpyrrolidone (PVP) was added, and the mass ratio of Al(NO3)3 to PVP was controlled at 1:(0.5~1). The mixture was stirred thoroughly to form a uniform spinning solution. After electrospinning, the solution was placed in a muffle furnace for pre-oxidation and calcination treatment, followed by Ar / H2 plasma treatment. The resulting composite carrier was obtained.

[0016] (2) The composite carrier is ultrasonically dispersed in a Zn-containing medium. 2+ With Ce 3+ In a mixed solution of Zn(NO3)2·6H2O and Ce(NO3)3·6H2O with a molar ratio of 5:1, the mixture was dispersed evenly and heated to 70-80℃. Hexadecyltrimethylammonium bromide (CTAB) was added and stirred to form a suspension. Under constant temperature conditions, 2-5M dilute ammonia water was added dropwise while stirring, and the pH was controlled at 8-8.5. After the addition was completed, the mixture was aged at 70-80℃ for 2-3 hours, filtered, washed with deionized water until neutral, and then dried under vacuum at 60-70℃ for 20-26 hours to obtain a preliminary Zn / Ce-loaded support.

[0017] (3) The Zn / Ce-loaded support was ultrasonically dispersed in Cu(NO3)2·3H2O solution. After uniform dispersion, the temperature was raised to 60~70℃, CTAB was added, and the mixture was stirred. Under constant temperature conditions, 1~2M dilute sodium carbonate was added dropwise while stirring, and the pH was controlled to be 6~6.5. After the addition was completed, the mixture was aged at 60~70℃ for 2~3h, filtered, washed with deionized water until neutral, and then dried under vacuum conditions at 60~70℃ for 20~26h to obtain the precursor material.

[0018] (4) Place the precursor material in a muffle furnace, and after the temperature is programmed and cooled to room temperature under a flowing air atmosphere, place it in a tube reduction furnace, introduce a reducing gas of NH3:H2=3:1, maintain the reducing atmosphere, first raise the temperature to 200~250℃ at a heating rate of 2~3℃ / min, hold for 2~3h, then continue to raise the temperature to 300~350℃ at a heating rate of 3~4℃ / min, hold for 1~2h, and then cool to room temperature and take it out.

[0019] Furthermore, the mass ratio of anhydrous ethanol to deionized water in the mixed solvent described in step (1) is 1:1.

[0020] Further, the pre-oxidation and calcination treatment in step (1) specifically involves: heating to 250-300℃ at a heating rate of 1-2℃ / min, holding for 2-3 hours for pre-oxidation, and then heating to 500-600℃ at a rate of 2-3℃ / min, holding for 3-4 hours, and then calcining.

[0021] Furthermore, during the Ar / H2 plasma treatment described in step (1), an Ar / H2 mixed gas is introduced, with Ar:H2=9:1, the power is adjusted to 50W, and the treatment time is 8~10min.

[0022] Further, the total mass ratio of hexadecyltrimethylammonium bromide to the metal salt in step (2) is 1:(10~20);

[0023] The total mass ratio of CTAB to metal salt in step (3) is 1:(10~20).

[0024] Furthermore, the air flow rate mentioned in step (4) is 60~80 mL / min;

[0025] The specific temperature program is as follows: first, raise the temperature to 250℃ at a rate of 1~2℃ / min, hold for 1~2 hours, and then raise the temperature to 400~450℃ at a rate of 2~3℃ / min, hold for 3~4 hours.

[0026] The flow rate of the reducing gas is 100~200 mL / min.

[0027] Furthermore, during the gas-phase amination reaction described in step S2, the reaction temperature is 300~450℃ and the reaction pressure is 2~5MPaG.

[0028] The present invention has the following advantages over the prior art:

[0029] 1. In the production and synthesis of methylamine, this invention recycles the azeotropics and mixed amines generated during the production process, significantly improving the utilization rate of raw materials and reducing waste emissions, making it environmentally friendly. Before synthesis, a staged heating method is adopted. First, the temperature is raised to 120~130℃ through a low-temperature heat exchanger, then the residual heat of the reaction gas is used to raise the temperature to 320℃ through a three-series high-temperature heat exchanger, and finally the temperature is electrically heated to the reaction temperature. This staged heating method effectively improves energy utilization and reduces production energy consumption.

[0030] 2. The catalyst prepared by this invention through a unique preparation process has high selectivity for the synthesis of methylamine, which can significantly reduce the production of by-products and improve the yield and purity of the product. In addition, the catalyst of this invention has good stability. Ar / H2 plasma treatment enhances the catalyst's resistance to carbon deposition. It still has high activity after 24 hours of continuous operation and has a long service life. Detailed Implementation

[0031] To further explain the present invention, the following specific embodiments are described.

[0032] Example 1

[0033] A method for synthesizing methylamine includes the following steps:

[0034] S1. Methanol, liquid ammonia and azeotropic mixtures and mixed amines produced during the production of methylamine are pressurized to 2 MPaG by pumps and then mixed. The resulting raw material mixture is then heated to 120°C by a low-temperature heat exchanger, then vaporized to 140°C by a start-up vaporizer, then heated to 320°C by a three-series high-temperature heat exchanger, and finally heated to 380°C by an electric heating furnace before entering the synthesis tower.

[0035] The methanol is used as the reference raw material, the molar ratio of methanol to ammonia is 1:1.5, the azeotrope is added at 5% of the total feed, and the mixed amine is added at 10% of the total feed.

[0036] S2. Gas-phase amination is carried out in the catalyst layer inside the synthesis tower at a reaction temperature of 300℃ and a reaction pressure of 2MPaG.

[0037] The catalyst layer described in step S2 is filled with catalyst, and the preparation of the catalyst includes the following steps:

[0038] (1) Mix Al(NO3)3·9H2O with tetraethyl orthosilicate and phosphoric acid according to n(Al 3+ ):n(Si):n(PO4 3- The solution was dissolved in a mixture of deionized water and anhydrous ethanol (mass ratio of anhydrous ethanol to deionized water is 1:1) with a molar ratio of 5:2:1. Then polyvinylpyrrolidone (PVP) was added, and the mass ratio of Al(NO3)3 to PVP was controlled at 1:0.5. The mixture was stirred thoroughly to form a uniform spinning solution. After electrospinning, the solution was placed in a muffle furnace and heated to 250°C at a heating rate of 1°C / min. It was held at this temperature for 2 hours for pre-oxidation. Then the temperature was increased to 500°C at a heating rate of 2°C / min and held at this temperature for 3 hours. After calcination, the solution was subjected to Ar / H2 plasma treatment to obtain the composite carrier.

[0039] During the Ar / H2 plasma treatment, an Ar / H2 mixed gas is introduced, with Ar:H2=9:1, the power is adjusted to 50W, and the treatment time is 8min.

[0040] (2) The composite carrier is ultrasonically dispersed in a Zn-containing medium. 2+ With Ce 3+ In a mixed solution of Zn(NO3)2·6H2O and Ce(NO3)3·6H2O with a molar ratio of 5:1, the mixture was dispersed evenly and then heated to 70℃. Hexadecyltrimethylammonium bromide (CTAB) was added, with a total mass ratio of hexadecyltrimethylammonium bromide to metal salt of 1:10. The mixture was stirred to form a suspension. Under constant temperature conditions, 2M dilute ammonia water was added dropwise while stirring, and the pH was controlled at 8. After the addition was completed, the mixture was aged at 70℃ for 2 hours. The mixture was then filtered, washed with deionized water until neutral, and then dried under vacuum at 60℃ for 20 hours to obtain a preliminary Zn / Ce-loaded support.

[0041] (3) The Zn / Ce-loaded support was ultrasonically dispersed in Cu(NO3)2·3H2O solution. After uniform dispersion, the temperature was raised to 60℃, and CTAB was added. The total mass ratio of CTAB to metal salt was 1:10. The mixture was stirred and mixed. 1M dilute sodium carbonate was added dropwise while stirring under constant temperature conditions, and the pH was controlled to 6. After the addition was completed, the mixture was aged at 60℃ for 2 hours. The mixture was then filtered, washed with deionized water until neutral, and then dried under vacuum at 60℃ for 20 hours to obtain the precursor material.

[0042] (4) Place the precursor material in a muffle furnace. Under a flowing air atmosphere, the air flow rate is 60 mL / min. First, raise the temperature to 250°C at a heating rate of 1°C / min and hold for 1 h. Then, raise the temperature to 400°C at a heating rate of 2°C / min and hold for 3 h. After cooling to room temperature, place it in a tube-type reduction furnace and introduce a reducing gas with NH3:H2=3:1 at a flow rate of 100 mL / min. Maintain the reducing atmosphere. First, raise the temperature to 200°C at a heating rate of 2°C / min and hold for 2 h. Then, continue to raise the temperature to 300°C at a heating rate of 3°C / min and hold for 1 h. After cooling to room temperature, it can be taken out.

[0043] S3. The crude amine gas generated by the gas amination reaction is condensed by heat, and then the products are separated and the tail gas and wastewater are treated.

[0044] Example 2

[0045] A method for synthesizing methylamine includes the following steps:

[0046] S1. Methanol, liquid ammonia and azeotropic mixtures and mixed amines produced during the production of methylamine are pressurized to 3.5 MPaG by pumps and then mixed. The resulting raw material mixture is then heated to 125°C by a low-temperature heat exchanger, then vaporized to 140°C by a start-up vaporizer, then heated to 320°C by a three-series high-temperature heat exchanger, and finally heated to 410°C by an electric heater before entering the synthesis tower.

[0047] The methanol is used as the reference raw material, the molar ratio of methanol to ammonia is 1:2.5, the azeotrope is added at 8% of the total feed, and the mixed amine is added at 15% of the total feed.

[0048] S2. Gas-phase amination is carried out in the catalyst layer inside the synthesis tower at a reaction temperature of 400℃ and a reaction pressure of 3.5MPaG.

[0049] The catalyst layer described in step S2 is filled with catalyst, and the preparation of the catalyst includes the following steps:

[0050] (1) Mix Al(NO3)3·9H2O with tetraethyl orthosilicate and phosphoric acid according to n(Al 3+ ):n(Si):n(PO4 3-The solution was dissolved in a mixture of deionized water and anhydrous ethanol (mass ratio of anhydrous ethanol to deionized water was 1:1) at a molar ratio of 5:2:1. Then polyvinylpyrrolidone (PVP) was added, and the mass ratio of Al(NO3)3 to PVP was controlled at 1:0.75. The mixture was stirred thoroughly to form a uniform spinning solution. After electrospinning, the solution was placed in a muffle furnace and heated to 270°C at a heating rate of 1.5°C / min. The solution was held at this temperature for 2.5 h for pre-oxidation. Then the solution was heated to 550°C at a heating rate of 2.5°C / min and held at this temperature for 3.5 h. After calcination, the solution was subjected to Ar / H2 plasma treatment to obtain the composite carrier.

[0051] During the Ar / H2 plasma treatment, an Ar / H2 mixed gas is introduced, with Ar:H2=9:1, the power is adjusted to 50W, and the treatment time is 9min.

[0052] (2) The composite carrier is ultrasonically dispersed in a Zn-containing medium. 2+ With Ce 3+ In a mixed solution of Zn(NO3)2·6H2O and Ce(NO3)3·6H2O with a molar ratio of 5:1, the mixture was dispersed evenly and then heated to 75°C. Hexadecyltrimethylammonium bromide (CTAB) was added, with a total mass ratio of hexadecyltrimethylammonium bromide to metal salt of 1:15. The mixture was stirred to form a suspension. Under constant temperature conditions, 3M dilute ammonia water was added dropwise while stirring, and the pH was controlled at 8.2. After the addition was completed, the mixture was aged at 75°C for 2.5 hours. The mixture was then filtered, washed with deionized water until neutral, and then dried under vacuum at 65°C for 23 hours to obtain a preliminary Zn / Ce-loaded support.

[0053] (3) The Zn / Ce-loaded support was ultrasonically dispersed in Cu(NO3)2·3H2O solution. After uniform dispersion, the temperature was raised to 65℃, and CTAB was added. The total mass ratio of CTAB to metal salt was 1:15. The mixture was stirred and mixed. 1.5M dilute sodium carbonate was added dropwise while stirring under constant temperature conditions, and the pH was controlled at 6.2. After the addition was completed, the mixture was aged at 65℃ for 2.5h. The mixture was then filtered, washed with deionized water until neutral, and then dried under vacuum at 65℃ for 23h to obtain the precursor material.

[0054] (4) Place the precursor material in a muffle furnace. Under a flowing air atmosphere, the air flow rate is 70 mL / min. First, raise the temperature to 250℃ at a heating rate of 1.5℃ / min and hold for 1.5 h. Then, raise the temperature to 430℃ at a heating rate of 2.5℃ / min and hold for 3.5 h. After cooling to room temperature, place it in a tube reduction furnace and introduce a reducing gas with NH3:H2=3:1 at a flow rate of 150 mL / min. Maintain the reducing atmosphere. First, raise the temperature to 220℃ at a heating rate of 2.5℃ / min and hold for 2.5 h. Then, continue to raise the temperature to 320℃ at a heating rate of 3.5℃ / min and hold for 1.5 h. After cooling to room temperature, it can be taken out.

[0055] S3. The crude amine gas generated by the gas amination reaction is condensed by heat, and then the products are separated and the tail gas and wastewater are treated.

[0056] Example 3

[0057] A method for synthesizing methylamine includes the following steps:

[0058] S1. Methanol, liquid ammonia and methylamine azeotropes and mixed amines produced during production are pressurized to 5 MPaG by pumps and then mixed. The resulting raw material mixture is heated to 130°C by a low-temperature heat exchanger, then vaporized to 140°C by a start-up vaporizer, then heated to 320°C by a three-series high-temperature heat exchanger, and finally heated to 450°C by an electric heating furnace before entering the synthesis tower.

[0059] The methanol is used as the reference raw material, the molar ratio of methanol to ammonia is 1:4, the azeotrope is added at 15% of the total feed mass, and the mixed amine is added at 20% of the total feed mass.

[0060] S2. Gas-phase amination is carried out in the catalyst layer inside the synthesis tower at a reaction temperature of 450℃ and a reaction pressure of 5MPaG.

[0061] The catalyst layer described in step S2 is filled with catalyst, and the preparation of the catalyst includes the following steps:

[0062] (1) Mix Al(NO3)3·9H2O with tetraethyl orthosilicate and phosphoric acid according to n(Al 3+ ):n(Si):n(PO4 3-The solution was dissolved in a mixed solvent of deionized water and anhydrous ethanol (mass ratio of anhydrous ethanol to deionized water is 1:1) with a molar ratio of 5:2:1. Then polyvinylpyrrolidone (PVP) was added, and the mass ratio of Al(NO3)3 to PVP was controlled at 1:1. The mixture was stirred thoroughly to form a uniform spinning solution. After electrospinning, the solution was placed in a muffle furnace and heated to 300°C at a heating rate of 2°C / min. It was held at this temperature for 3 hours for pre-oxidation. Then the temperature was increased to 600°C at a heating rate of 3°C / min and held at this temperature for 4 hours. After calcination, the solution was subjected to Ar / H2 plasma treatment to obtain the composite carrier.

[0063] During the Ar / H2 plasma treatment, an Ar / H2 mixed gas is introduced, with Ar:H2=9:1, the power is adjusted to 50W, and the treatment time is 10min.

[0064] (2) The composite carrier is ultrasonically dispersed in a Zn-containing medium. 2+ With Ce 3+ In a mixed solution of Zn(NO3)2·6H2O and Ce(NO3)3·6H2O with a molar ratio of 5:1, the mixture was dispersed evenly and heated to 80℃. Hexadecyltrimethylammonium bromide (CTAB) was added, with a total mass ratio of hexadecyltrimethylammonium bromide to metal salt of 1:20. The mixture was stirred to form a suspension. Under constant temperature conditions, 5M dilute ammonia water was added dropwise while stirring, and the pH was controlled at 8.5. After the addition was completed, the mixture was aged at 80℃ for 3 hours. The mixture was then filtered, washed with deionized water until neutral, and then dried under vacuum at 70℃ for 26 hours to obtain a preliminary Zn / Ce-loaded support.

[0065] (3) The Zn / Ce-loaded support was ultrasonically dispersed in Cu(NO3)2·3H2O solution. After uniform dispersion, the temperature was raised to 70℃, and CTAB was added. The total mass ratio of CTAB to metal salt was 1:20. The mixture was stirred and mixed. 2M dilute sodium carbonate was added dropwise while stirring under constant temperature conditions. The pH was controlled at 6.5. After the addition was completed, the mixture was aged at 70℃ for 3 hours. The mixture was filtered, washed with deionized water until neutral, and then dried under vacuum at 70℃ for 26 hours to obtain the precursor material.

[0066] (4) Place the precursor material in a muffle furnace. Under a flowing air atmosphere, the air flow rate is 80 mL / min. First, raise the temperature to 250°C at a heating rate of 2°C / min and hold for 2 hours. Then, raise the temperature to 450°C at a heating rate of 3°C / min and hold for 4 hours. After cooling to room temperature, place it in a tube-type reduction furnace and introduce a reducing gas with NH3:H2=3:1 at a flow rate of 200 mL / min. Maintain the reducing atmosphere. First, raise the temperature to 250°C at a heating rate of 3°C / min and hold for 3 hours. Then, continue to raise the temperature to 350°C at a heating rate of 4°C / min and hold for 2 hours. After cooling to room temperature, it can be taken out.

[0067] S3. The crude amine gas generated by the gas amination reaction is condensed by heat, and then the products are separated and the tail gas and wastewater are treated.

[0068] Comparative Example 1

[0069] Compared with Example 2, in the preparation of the catalyst, the tetraethyl orthosilicate and phosphoric acid in step (1) are omitted, and the other steps are the same as in Example 2.

[0070] Comparative Example 2

[0071] Compared with Example 2, Comparative Example 2 omits the plasma treatment in step (1) in the preparation of the catalyst, while the other steps are the same as in Example 2.

[0072] Comparative Example 3

[0073] Compared with Example 2, Comparative Example 3 differs from Example 2 in that the addition of Ce(NO3)3·6H2O in the preparation of the catalyst, while the other steps are the same.

[0074] Performance testing

[0075] Methylamine was synthesized using the methods described in Examples 1-3 and Comparative Examples 1-3, respectively. The raw material conversion rate, methylamine yield, and product purity of each example and comparative example were then tested. Three parallel tests were performed for each group of tests, and the average value was taken as the final test result.

[0076] The test results are shown in Table 1 below.

[0077] Table 1

[0078] Grouping Raw material conversion rate (%) Methylamine yield (%) Product purity (%) Example 1 86.8 81.5 91.2 Example 2 87.6 82.3 92.8 Example 3 85.5 82.4 91.3 Comparative Example 1 75.3 73.3 85.5 Comparative Example 2 68.6 65.3 83.6 Comparative Example 3 65.2 62.6 84.8

[0079] As shown in Table 1 above, the raw material conversion rate, methylamine yield, and product purity of Examples 1-3 are all better than those of the comparative example, indicating that the catalyst of the present invention can not only effectively improve the raw material conversion rate, but also significantly improve the methylamine yield and product purity.

[0080] To further compare the technical effects of the present invention, a continuous reaction test was conducted using the technical solution of Example 2. After 24 hours of reaction, the raw material conversion rate, methylamine yield, and product purity were 86.3%, 80.9%, and 94.9%, respectively, indicating that the catalyst of the present invention has good stability and a long service life.

[0081] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for synthesizing methylamine, characterized in that, Includes the following steps: S1. Methanol, liquid ammonia and azeotropic mixtures and mixed amines produced during the production of methylamine are pressurized by pumps and then mixed. After passing through multiple heat exchange, gasification and electric heating to 380~450℃, they enter the synthesis tower. S2. A gas-phase amination reaction is carried out in the catalyst layer inside the synthesis tower; The catalyst layer is filled with catalyst, and the preparation of the catalyst includes the following steps: (1) Mix Al(NO3)3·9H2O with tetraethyl orthosilicate and phosphoric acid according to n(Al 3+ ):n(Si):n(PO4 3- The mixture of Al(NO3)3 and polyvinylpyrrolidone was dissolved in a mixed solvent of deionized water and anhydrous ethanol at a molar ratio of 5:2:

1. Then, polyvinylpyrrolidone was added, and the mass ratio of Al(NO3)3 to polyvinylpyrrolidone was controlled at 1:(0.5~1). The mixture was stirred thoroughly to form a uniform spinning solution. After electrospinning, the solution was placed in a muffle furnace for pre-oxidation and calcination treatment, followed by Ar / H2 plasma treatment. The resulting composite carrier was obtained. (2) The composite carrier is ultrasonically dispersed in a Zn-containing medium. 2+ With Ce 3+ In a mixed solution of Zn(NO3)2·6H2O and Ce(NO3)3·6H2O with a molar ratio of 5:1, the mixture was dispersed evenly and heated to 70-80℃. Hexadecyltrimethylammonium bromide was added and stirred to form a suspension. Under constant temperature conditions, 2-5M dilute ammonia water was added dropwise while stirring, and the pH was controlled at 8-8.

5. After the addition was completed, the mixture was aged at 70-80℃ for 2-3 hours, filtered, washed with deionized water until neutral, and then dried under vacuum at 60-70℃ for 20-26 hours to obtain a preliminary Zn / Ce-loaded support. (3) The Zn / Ce-loaded support was ultrasonically dispersed in Cu(NO3)2·3H2O solution. After uniform dispersion, the temperature was raised to 60~70℃, cetyltrimethylammonium bromide was added, and the mixture was stirred. Under constant temperature conditions, 1~2M dilute sodium carbonate was added dropwise while stirring, and the pH was controlled at 6~6.

5. After the addition was completed, the mixture was aged at 60~70℃ for 2~3h, filtered, washed with deionized water until neutral, and then dried under vacuum conditions at 60~70℃ for 20~26h to obtain the precursor material. (4) Place the precursor material in a muffle furnace, and after the temperature is programmed and cooled to room temperature under a flowing air atmosphere, place it in a tube reduction furnace, introduce a reducing gas of NH3:H2=3:1, maintain the reducing atmosphere, first raise the temperature to 200~250℃ at a heating rate of 2~3℃ / min, hold for 2~3h, then continue to raise the temperature to 300~350℃ at a heating rate of 3~4℃ / min, hold for 1~2h, and then cool to room temperature and take it out. S3. The crude amine gas generated by the gas-phase amination reaction is then subjected to thermal condensation for product separation and treatment of tail gas and wastewater.

2. The method for producing and synthesizing methylamine according to claim 1, characterized in that, In step S1, methanol is used as the reference raw material, the molar ratio of methanol to ammonia is 1:(1.5~4), the mass of azeotrope added accounts for 5~15% of the total feed, and the mass of mixed amine added accounts for 10~20% of the total feed.

3. The method for producing and synthesizing methylamine according to claim 1, characterized in that, The specific operation of step S1 is as follows: methanol, liquid ammonia and azeotrope and mixed amine produced in the production process of methylamine are respectively pumped to 2~5MPaG and then mixed. The resulting raw material mixture is then heated to 120~130℃ through a low temperature heat exchanger, then vaporized to 140℃ through a start-up vaporizer, then heated to 320℃ through a three-series high temperature heat exchanger with the reaction gas, and finally heated to 380~450℃ by an electric heating furnace before entering the synthesis tower.

4. The method for producing and synthesizing methylamine according to claim 1, characterized in that, The mass ratio of anhydrous ethanol to deionized water in the mixed solvent described in step (1) is 1:

1.

5. The method for producing and synthesizing methylamine according to claim 1, characterized in that, The pre-oxidation and calcination treatment described in step (1) is as follows: the temperature is raised to 250-300℃ at a heating rate of 1-2℃ / min, and held for 2-3 hours for pre-oxidation. Then, the temperature is raised to 500-600℃ at a rate of 2-3℃ / min, and held for 3-4 hours for calcination.

6. The method for producing and synthesizing methylamine according to claim 1, characterized in that, During the Ar / H2 plasma treatment described in step (1), an Ar / H2 mixed gas is introduced, with Ar:H2=9:1, the power is adjusted to 50W, and the treatment time is 8~10min.

7. The method for producing and synthesizing methylamine according to claim 1, characterized in that, The total mass ratio of hexadecyltrimethylammonium bromide to the metal salt in step (2) is 1:(10~20); The total mass ratio of hexadecyltrimethylammonium bromide to metal salt in step (3) is 1:(10~20).

8. The method for producing and synthesizing methylamine according to claim 1, characterized in that, The air flow rate mentioned in step (4) is 60~80 mL / min; The specific temperature program is as follows: first, raise the temperature to 250℃ at a rate of 1~2℃ / min, hold for 1~2 hours, and then raise the temperature to 400~450℃ at a rate of 2~3℃ / min, hold for 3~4 hours. The flow rate of the reducing gas is 100~200 mL / min.

9. The method for producing and synthesizing methylamine according to claim 1, characterized in that, During the gas-phase amination reaction described in step S2, the reaction temperature is 300~450℃ and the reaction pressure is 2~5MPaG.