Preparation method of phenylmethylamine

Abstract

The invention relates to a preparation method of phenylmethylamine. The technical scheme adopted by the invention for mainly solving the problems of high catalyst loss, low production efficiency and high intermittent operation labor intensity is as follows: the preparation method of the phenylmethylamine comprises the following steps: mixing the raw material of cyanobenzene with a solvent material or at least one of one part of product materials in a mixing unit, introducing the mixture into a fixed bed hydrogenation reactor to be in contact with hydrogen and a catalyst and carry out multi-phase continuous hydrogenation reaction to obtain a product material containing phenylmethylamine, separating the product material to obtain a phenylmethylamine product, wherein the catalyst is a metal loaded catalyst; and the metal is selected from at least one of Pd, Pt, Cu, Ni, Mo and Fe. The preparation method can be used for preparing phenylmethylamine.

Description

Technical Field

[0001] This invention relates to a method for preparing benzylamine. Background Technology

[0002] In modern industrial production, aromatic primary amines are an important class of chemical intermediates, and benzylamine is one of the most important products among them.

[0003] Benzylamine is a strong basicity and can react with phenol, formic acid, and p-methylphenol to form addition products. It can also react with acyl chlorides, acid anhydrides or esters, aldehydes, ketones, and halogenated hydrocarbons. With acyl chlorides, acid anhydrides, or esters, it forms N-benzylamides; with halogenated hydrocarbons, it forms N-substituted benzylamines; and with aldehydes and ketones, it forms N-benzylimines. As an important organic chemical raw material and fine chemical intermediate, benzylamine is widely used in the synthesis of pharmaceuticals (pharmaceuticals and pesticides), dyes, synthetic resins, corrosion inhibitors and functional additives, explosives, chemical reagents, CO2 absorbents, and curing agents (stabilizers) for rubber and plastics. Benzylamine can also be used in microcrystalline analysis to determine molybdates, vanadates, tungstates, titanium, cobalt, cerium, lanthanum, praseodymium, and neodymium. In the pharmaceutical industry, it is mainly used to synthesize homosulfamin and sulfamilon acetate. With the development and production of more related fine chemical products, aromatic primary amines have a very broad application prospect, and their demand is growing very rapidly.

[0004] There are many processes for producing benzylamine, including: (1) reducing aromatic nitro compounds with hydrogen; (2) reacting halogenated aromatic compounds with ammonia at a certain pressure and high temperature; (3) reacting ammonia with phenol; and (4) catalytic hydrogenation of aromatic nitriles.

[0005] The presence of aromatic nitro compounds has the following disadvantages: (1) a large amount of sulfuric acid or nitric acid is required as the nitrating agent for the aromatic compounds, and a large amount of alkali, such as sodium hydroxide, is required in the neutralization step of the reaction, resulting in a high concentration of saline solution. In addition, as described in Japanese Patent Application Publication No. JP48-67229, nitrogen oxide gas generated in the step of forming nitro compounds causes air pollution. In the nitration of phenol, in addition to obtaining the desired nitro compound, various isomer byproducts are also generated. Since the isomers are difficult to separate, pure aniline is difficult to obtain.

[0006] Method (2) using halogenated aromatic compounds has a key problem: due to the use of highly corrosive chlorine gas (bromine water), expensive corrosion-resistant equipment must be installed during the preparation of halogenated aromatic compounds. Furthermore, even at higher temperatures and pressures, the yield of the target product remains very low, and this process is rarely chosen in actual production.

[0007] The catalyst preparation for the reaction of phenol with ammonia is relatively difficult, the reaction temperature is high, resulting in a large number of byproducts. The key issue is that the stability of the catalyst has not yet been resolved, and its general service life is only about 100 hours, which makes it impossible to carry out effective industrial applications.

[0008] The catalytic hydrogenation of aromatic nitriles to prepare aromatic amines is an important research area both domestically and internationally, but related synthetic studies are relatively few. Domestic and international research mainly focuses on the batch-type catalytic hydrogenation process of benzonitrile, primarily using Raney Ni (or Raney Cu) as a catalyst. Chinese Patent 102276377A discloses a method for preparing benzylamine, in which aromatic nitrile reactants react with sodium alkoxide in an organic solvent under the catalysis of Raney copper. The molar ratio of sodium alkoxide to the compound is 2-4:1, the amount of Raney copper is 0.05-0.15 times the molar amount of the compound, the reaction temperature is 30-70℃, and the reaction time is 2-6 hours. After the reaction, the resulting reaction solution is cooled to room temperature, filtered, and then the filtrate is distilled to obtain the target compound, with a maximum yield of 89.0%. Although this method has a high yield, the use of a super-basic sodium alkoxide as a catalyst necessitates the use of an aprotic solvent, and the subsequent separation process consumes acid, generating a large amount of salt wastewater, severely limiting its application. In this type of reaction, the catalyst recycling rate is low in batch reactors, and its activity is significantly reduced due to the adsorption and accumulation of polymer condensation products on the catalyst surface. In addition, the large amount of solvent added to improve the yield makes subsequent separation and waste treatment difficult, resulting in high catalyst loss and low production efficiency. The operation of batch reactors involves a large amount of manual labor, resulting in high pollution and high emissions. With the rapid increase in downstream market demand for aniline products and the gradual improvement of environmental protection requirements, the low production efficiency and high pollution of batch reactors can no longer meet future needs. Summary of the Invention

[0009] The technical problem this invention aims to solve is the high catalyst loss, low production efficiency, and high labor intensity associated with batch operation in existing technologies. This invention provides a novel method for preparing abenzylamine. The apparatus used in the preparation of abenzylamine offers advantages such as low catalyst loss, high production efficiency, and low labor intensity during batch operation.

[0010] To solve the above problems, the present invention adopts the following technical solution: a method for preparing benzonitrile, comprising mixing at least one of benzonitrile raw material and solvent material or a portion of product material in a mixing unit and then entering a fixed-bed hydrogenation reactor to contact with hydrogen and catalyst for multiphase continuous hydrogenation reaction, to obtain product material including benzonitrile, and obtaining benzonitrile product after separation; wherein the catalyst is a metal supported catalyst, and the metal is selected from at least one of Pd, Pt, Cu, Ni, Mo, and Fe.

[0011] In the above technical solution, preferably, the catalyst is supported by alumina, magnesium oxide, silicon dioxide, titanium dioxide, molecular sieve or activated carbon.

[0012] In the above technical solution, preferably, the mass fraction of benzonitrile in the raw material is 2.5-99%.

[0013] In the above technical solution, preferably, the solvent is selected from at least one of liquid ammonia, alcohols, benzene compounds, amines, and nitriles, and the nitriles do not include benzonitrile.

[0014] In the above technical solution, preferably, a portion of the product material in the mixing unit is a non-aniline product material after the separation of aniline product.

[0015] In the above technical solution, preferably, the weight ratio of benzonitrile to solvent is 0.1 to 10:1, and the weight ratio of the portion of product material entering the mixing unit to benzonitrile is 0.01 to 1:1.

[0016] In the above technical solution, preferably, the mass content of the metal in the catalyst is 0.01-10%.

[0017] In the above technical solution, preferably, the reaction conditions of the fixed-bed hydrogenation reactor are: a reaction temperature of 70-130℃ and a benzonitrile mass hourly space velocity of 0.4-3.6 h⁻¹. -1 The molar ratio of hydronitrogen to nitrile is 5-200:1, and the reaction pressure is 0.2-10 MPaG.

[0018] More preferably, in the above technical solution, the reaction conditions of the fixed-bed hydrogenation reactor are: a reaction temperature of 70-100℃ and a benzonitrile mass hourly space velocity of 0.4-1.2 h⁻¹. -1 The molar ratio of hydronitrogen to nitrile is 10-100:1, and the reaction pressure is 1-3 MPaG.

[0019] In the above technical solution, more preferably, the solvent is selected from at least one of ethanol, methanol, isopropanol, n-butanol, n-pentane, liquid ammonia, toluene, ethylbenzene, benzene, acetonitrile, and ammonia water.

[0020] In this invention, the molar ratio of hydronitrogen is the molar ratio of hydrogen to benzonitrile.

[0021] This invention produces anitrogenine from benzonitrile via a multiphase hydrogenation reaction. The method employs a fixed-bed reaction, and the products can be separated by simple distillation, avoiding the problems of high catalyst loss, low production efficiency, and high labor intensity associated with traditional anitrogenine synthesis methods. This improves operational stability and meets environmental protection requirements. Simultaneously, with the selected catalyst system, the reaction products are only anitrogenine and toluene. After simple separation, toluene can be directly fed into the benzonitrile synthesis section to react with ammonia to produce benzonitrile (the reaction raw material of this patent), achieving a selectivity of over 98% for anitrogenine and demonstrating excellent technical performance.

[0022] The present invention will be further illustrated by the following embodiments, but is not limited to these embodiments. Detailed Implementation

[0023] 【Example 1】

[0024] Catalyst preparation: Weigh 3.33 g of palladium chloride and add 100 g of deionized water to prepare solution A. Take 5 g of the above solution and add it to deionized water. Adjust the pH of the solution to 0 by adding concentrated hydrochloric acid dropwise. Impregnate the solution onto 20 g of γ-Al₂O₃ type alumina support that has been crushed to 30-50 mesh, so that the palladium content in the catalyst is 0.5 wt%. Dry the palladium-impregnated support at 120 °C for 12 h. Calcinate the dried catalyst at 500 °C for 4 h in air to obtain the catalyst precursor. Store for later use.

[0025] The prepared catalyst was loaded into a stainless steel fixed-bed reactor with an inner diameter of φ12mm. The reaction temperature was controlled at 40-130℃, and the mass hourly space velocity of benzonitrile was 0.5-3.6h. -1 The weight ratio of benzonitrile to solvent is 99:1, and the weight ratio of the portion of product material entering the mixing unit to benzonitrile is 0.01:1. The solvent is ethanol, the molar ratio of hydrogen to nitrile is 20, and the reaction pressure is 1.5 MPaG. The product is collected and analyzed after cooling.

[0026] For the entire process, the non-aniline components (mainly toluene) in the reaction products are separated and returned to the benzonitrile synthesis section to react with ammonia to produce benzonitrile raw material.

[0027] The reaction results are shown in Table 1.

[0028] 【Example 2】

[0029] Following the conditions and steps described in Example 1, the weight ratio of the portion of product material entering the mixing unit to benzonitrile was 1:1, and the reaction results are shown in Table 1.

[0030] 【Example 3】

[0031] Following the conditions and steps described in Example 1, the solvent was ethanol, and the weight ratio of benzonitrile to ethanol was 1:1. The reaction results are shown in Table 1.

[0032] 【Example 4】

[0033] Following the conditions and steps described in Example 1, the solvent was diethylamine, and the weight ratio of benzonitrile to diethylamine was 1:1. The reaction results are shown in Table 1.

[0034] 【Examples 5-10】

[0035] Following the conditions and steps described in Example 1, the type and percentage of metal in the catalyst were changed, as detailed in Table 2.

[0036] Table 1

[0037]

[0038]

[0039] Table 2

[0040]

[0041] [Comparative Example]

[0042] Table 3

[0043]

[0044] Data source: DOI:10.1016 / j.jcat.2010.06.013.

Examples

Embodiment 1

[0024] Catalyst preparation: Weigh 3.33g of palladium chloride, add 100g of deionized water to make solution A, take 5g of the above solution and add it into deionized water, add concentrated hydrochloric acid dropwise to adjust the pH of the solution to 0, impregnate until 20g has been broken to 30-50 mesh γ-Al 2 o 3 On the aluminum oxide carrier of type, make the content of metal palladium in the catalyst be 0.5wt%. The support impregnated with the palladium component was dried at 120° C. for 12 h. The dried catalyst was calcined at 500° C. for 4 h in an air atmosphere to obtain a catalyst precursor. Save for later.

[0025] Put the prepared catalyst into a stainless steel fixed-bed reactor with an inner diameter of φ12mm, control the reaction temperature at 40-130°C, and the mass space velocity of benzonitrile at 0.5-3.6h -1 , the weight ratio of the benzonitrile to the solvent is 99:1, and the weight ratio of the part of the product material entering the mixing unit to...

Embodiment 2

[0029] According to the conditions and steps described in Example 1, the weight ratio of the part of the product material entering the mixing unit to benzonitrile is 1:1, and the reaction results are shown in Table 1.

Embodiment 3

[0031] According to the conditions and steps described in Example 1, the solvent is ethanol, and the weight ratio of benzonitrile to ethanol is 1:1. The reaction results are shown in Table 1.

Technical Field

[0001] This invention relates to a method for preparing benzylamine. Background Technology

[0002] In modern industrial production, aromatic primary amines are an important class of chemical intermediates, and benzylamine is one of the most important products among them.

[0003] Benzylamine is a strong basicity and can react with phenol, formic acid, and p-methylphenol to form addition products. It can also react with acyl chlorides, acid anhydrides or esters, aldehydes, ketones, and halogenated hydrocarbons. With acyl chlorides, acid anhydrides, or esters, it forms N-benzylamides; with halogenated hydrocarbons, it forms N-substituted benzylamines; and with aldehydes and ketones, it forms N-benzylimines. As an important organic chemical raw material and fine chemical intermediate, benzylamine is widely used in the synthesis of pharmaceuticals (pharmaceuticals and pesticides), dyes, synthetic resins, corrosion inhibitors and functional additives, explosives, chemical reagents, CO2 absorbents, and curing agents (stabilizers) for rubber and plastics. Benzylamine can also be used in microcrystalline analysis to determine molybdates, vanadates, tungstates, titanium, cobalt, cerium, lanthanum, praseodymium, and neodymium. In the pharmaceutical industry, it is mainly used to synthesize homosulfamin and sulfamilon acetate. With the development and production of more related fine chemical products, aromatic primary amines have a very broad application prospect, and their demand is growing very rapidly.

[0004] There are many processes for producing benzylamine, including: (1) reducing aromatic nitro compounds with hydrogen; (2) reacting halogenated aromatic compounds with ammonia at a certain pressure and high temperature; (3) reacting ammonia with phenol; and (4) catalytic hydrogenation of aromatic nitriles.

[0005] The presence of aromatic nitro compounds has the following disadvantages: (1) a large amount of sulfuric acid or nitric acid is required as the nitrating agent for the aromatic compounds, and a large amount of alkali, such as sodium hydroxide, is required in the neutralization step of the reaction, resulting in a high concentration of saline solution. In addition, as described in Japanese Patent Application Publication No. JP48-67229, nitrogen oxide gas generated in the step of forming nitro compounds causes air pollution. In the nitration of phenol, in addition to obtaining the desired nitro compound, various isomer byproducts are also generated. Since the isomers are difficult to separate, pure aniline is difficult to obtain.

[0006] Method (2) using halogenated aromatic compounds has a key problem: due to the use of highly corrosive chlorine gas (bromine water), expensive corrosion-resistant equipment must be installed during the preparation of halogenated aromatic compounds. Furthermore, even at higher temperatures and pressures, the yield of the target product remains very low, and this process is rarely chosen in actual production.

[0007] The catalyst preparation for the reaction of phenol with ammonia is relatively difficult, the reaction temperature is high, resulting in a large number of byproducts. The key issue is that the stability of the catalyst has not yet been resolved, and its general service life is only about 100 hours, which makes it impossible to carry out effective industrial applications.

[0008] The catalytic hydrogenation of aromatic nitriles to prepare aromatic amines is an important research area both domestically and internationally, but related synthetic studies are relatively few. Domestic and international research mainly focuses on the batch-type catalytic hydrogenation process of benzonitrile, primarily using Raney Ni (or Raney Cu) as a catalyst. Chinese Patent 102276377A discloses a method for preparing benzylamine, in which aromatic nitrile reactants react with sodium alkoxide in an organic solvent under the catalysis of Raney copper. The molar ratio of sodium alkoxide to the compound is 2-4:1, the amount of Raney copper is 0.05-0.15 times the molar amount of the compound, the reaction temperature is 30-70℃, and the reaction time is 2-6 hours. After the reaction, the resulting reaction solution is cooled to room temperature, filtered, and then the filtrate is distilled to obtain the target compound, with a maximum yield of 89.0%. Although this method has a high yield, the use of a super-basic sodium alkoxide as a catalyst necessitates the use of an aprotic solvent, and the subsequent separation process consumes acid, generating a large amount of salt wastewater, severely limiting its application. In this type of reaction, the catalyst recycling rate is low in batch reactors, and its activity is significantly reduced due to the adsorption and accumulation of polymer condensation products on the catalyst surface. In addition, the large amount of solvent added to improve the yield makes subsequent separation and waste treatment difficult, resulting in high catalyst loss and low production efficiency. The operation of batch reactors involves a large amount of manual labor, resulting in high pollution and high emissions. With the rapid increase in downstream market demand for aniline products and the gradual improvement of environmental protection requirements, the low production efficiency and high pollution of batch reactors can no longer meet future needs. Summary of the Invention

[0009] The technical problem this invention aims to solve is the high catalyst loss, low production efficiency, and high labor intensity associated with batch operation in existing technologies. This invention provides a novel method for preparing abenzylamine. The apparatus used in the preparation of abenzylamine offers advantages such as low catalyst loss, high production efficiency, and low labor intensity during batch operation.

[0010] To solve the above problems, the present invention adopts the following technical solution: a method for preparing benzonitrile, comprising mixing at least one of benzonitrile raw material and solvent material or a portion of product material in a mixing unit and then entering a fixed-bed hydrogenation reactor to contact with hydrogen and catalyst for multiphase continuous hydrogenation reaction, to obtain product material including benzonitrile, and obtaining benzonitrile product after separation; wherein the catalyst is a metal supported catalyst, and the metal is selected from at least one of Pd, Pt, Cu, Ni, Mo, and Fe.

[0011] In the above technical solution, preferably, the catalyst is supported by alumina, magnesium oxide, silicon dioxide, titanium dioxide, molecular sieve or activated carbon.

[0012] In the above technical solution, preferably, the mass fraction of benzonitrile in the raw material is 2.5-99%.

[0013] In the above technical solution, preferably, the solvent is selected from at least one of liquid ammonia, alcohols, benzene compounds, amines, and nitriles, and the nitriles do not include benzonitrile.

[0014] In the above technical solution, preferably, a portion of the product material in the mixing unit is a non-aniline product material after the separation of aniline product.

[0015] In the above technical solution, preferably, the weight ratio of benzonitrile to solvent is 0.1 to 10:1, and the weight ratio of the portion of product material entering the mixing unit to benzonitrile is 0.01 to 1:1.

[0016] In the above technical solution, preferably, the mass content of the metal in the catalyst is 0.01-10%.

[0017] In the above technical solution, preferably, the reaction conditions of the fixed-bed hydrogenation reactor are: a reaction temperature of 70-130℃ and a benzonitrile mass hourly space velocity of 0.4-3.6 h⁻¹. -1 The molar ratio of hydronitrogen to nitrile is 5-200:1, and the reaction pressure is 0.2-10 MPaG.

[0018] More preferably, in the above technical solution, the reaction conditions of the fixed-bed hydrogenation reactor are: a reaction temperature of 70-100℃ and a benzonitrile mass hourly space velocity of 0.4-1.2 h⁻¹. -1 The molar ratio of hydronitrogen to nitrile is 10-100:1, and the reaction pressure is 1-3 MPaG.

[0019] In the above technical solution, more preferably, the solvent is selected from at least one of ethanol, methanol, isopropanol, n-butanol, n-pentane, liquid ammonia, toluene, ethylbenzene, benzene, acetonitrile, and ammonia water.

[0020] In this invention, the molar ratio of hydronitrogen is the molar ratio of hydrogen to benzonitrile.

[0021] This invention produces anitrogenine from benzonitrile via a multiphase hydrogenation reaction. The method employs a fixed-bed reaction, and the products can be separated by simple distillation, avoiding the problems of high catalyst loss, low production efficiency, and high labor intensity associated with traditional anitrogenine synthesis methods. This improves operational stability and meets environmental protection requirements. Simultaneously, with the selected catalyst system, the reaction products are only anitrogenine and toluene. After simple separation, toluene can be directly fed into the benzonitrile synthesis section to react with ammonia to produce benzonitrile (the reaction raw material of this patent), achieving a selectivity of over 98% for anitrogenine and demonstrating excellent technical performance.

[0022] The present invention will be further illustrated by the following embodiments, but is not limited to these embodiments. Detailed Implementation

[0023] 【Example 1】

[0024] Catalyst preparation: Weigh 3.33 g of palladium chloride and add 100 g of deionized water to prepare solution A. Take 5 g of the above solution and add it to deionized water. Adjust the pH of the solution to 0 by adding concentrated hydrochloric acid dropwise. Impregnate the solution onto 20 g of γ-Al₂O₃ type alumina support that has been crushed to 30-50 mesh, so that the palladium content in the catalyst is 0.5 wt%. Dry the palladium-impregnated support at 120 °C for 12 h. Calcinate the dried catalyst at 500 °C for 4 h in air to obtain the catalyst precursor. Store for later use.

[0025] The prepared catalyst was loaded into a stainless steel fixed-bed reactor with an inner diameter of φ12mm. The reaction temperature was controlled at 40-130℃, and the mass hourly space velocity of benzonitrile was 0.5-3.6h. -1 The weight ratio of benzonitrile to solvent is 99:1, and the weight ratio of the portion of product material entering the mixing unit to benzonitrile is 0.01:1. The solvent is ethanol, the molar ratio of hydrogen to nitrile is 20, and the reaction pressure is 1.5 MPaG. The product is collected and analyzed after cooling.

[0026] For the entire process, the non-aniline components (mainly toluene) in the reaction products are separated and returned to the benzonitrile synthesis section to react with ammonia to produce benzonitrile raw material.

[0027] The reaction results are shown in Table 1.

[0028] 【Example 2】

[0029] Following the conditions and steps described in Example 1, the weight ratio of the portion of product material entering the mixing unit to benzonitrile was 1:1, and the reaction results are shown in Table 1.

[0030] 【Example 3】

[0031] Following the conditions and steps described in Example 1, the solvent was ethanol, and the weight ratio of benzonitrile to ethanol was 1:1. The reaction results are shown in Table 1.

[0032] 【Example 4】

[0033] Following the conditions and steps described in Example 1, the solvent was diethylamine, and the weight ratio of benzonitrile to diethylamine was 1:1. The reaction results are shown in Table 1.

[0034] 【Examples 5-10】

[0035] Following the conditions and steps described in Example 1, the type and percentage of metal in the catalyst were changed, as detailed in Table 2.

[0036] Table 1

[0037]

[0038]

[0039] Table 2

[0040]

[0041] [Comparative Example]

[0042] Table 3

[0043]

[0044] Data source: DOI:10.1016 / j.jcat.2010.06.013.

Examples

Embodiment 1

[0024] Catalyst preparation: Weigh 3.33g of palladium chloride, add 100g of deionized water to make solution A, take 5g of the above solution and add it into deionized water, add concentrated hydrochloric acid dropwise to adjust the pH of the solution to 0, impregnate until 20g has been broken to 30-50 mesh γ-Al 2 o 3 On the aluminum oxide carrier of type, make the content of metal palladium in the catalyst be 0.5wt%. The support impregnated with the palladium component was dried at 120° C. for 12 h. The dried catalyst was calcined at 500° C. for 4 h in an air atmosphere to obtain a catalyst precursor. Save for later.

[0025] Put the prepared catalyst into a stainless steel fixed-bed reactor with an inner diameter of φ12mm, control the reaction temperature at 40-130°C, and the mass space velocity of benzonitrile at 0.5-3.6h -1 , the weight ratio of the benzonitrile to the solvent is 99:1, and the weight ratio of the part of the product material entering the mixing unit to...

Embodiment 2

[0029] According to the conditions and steps described in Example 1, the weight ratio of the part of the product material entering the mixing unit to benzonitrile is 1:1, and the reaction results are shown in Table 1.

Embodiment 3

[0031] According to the conditions and steps described in Example 1, the solvent is ethanol, and the weight ratio of benzonitrile to ethanol is 1:1. The reaction results are shown in Table 1.

Claims

1. A method for preparing benzylamine, comprising mixing at least one of benzonitrile raw material and solvent material or a portion of product material in a mixing unit and then entering a fixed-bed hydrogenation reactor to undergo a multiphase continuous hydrogenation reaction with hydrogen and catalyst to obtain a product material including benzylamine, which is then separated to obtain the benzylamine product; wherein the catalyst is a metal-supported catalyst, and the metal is selected from at least one of Pd, Pt, Cu, Ni, Mo, and Fe.

2. The method for preparing benzylamine according to claim 1, characterized in that... The catalyst is supported on alumina, magnesium oxide, silicon dioxide, titanium dioxide, molecular sieves, or activated carbon.

3. The method for preparing benzylamine according to claim 1, characterized in that... The benzonitrile content in the raw material is 2.5-99% by mass.

4. The method for preparing benzylamine according to claim 1, characterized in that... The solvent is selected from at least one of liquid ammonia, alcohols, benzene compounds, amines, and nitriles, excluding benzonitrile.

5. The method for preparing benzylamine according to claim 1, characterized in that... A portion of the product material in the mixing unit is non-aniline product material after the separation of aniline product.

6. The method for preparing benzylamine according to claim 1, characterized in that... The weight ratio of benzonitrile to solvent is 0.01 to 99:1, and the weight ratio of the portion of product material entering the mixing unit to benzonitrile is 0.01 to 39:

1.

7. The method for preparing benzylamine according to claim 1, characterized in that... The metal contains 0.01-10% by mass in the catalyst.

8. The method for preparing benzylamine according to claim 1, characterized in that... The reaction conditions in the fixed-bed hydrogenation reactor are: reaction temperature 70-130℃, benzonitrile mass hourly space velocity (WHSV) 0.4-3.6 h⁻¹. -1 The molar ratio of hydronitrogen to nitrile is 5-200:1, and the reaction pressure is 0.2-10 MPaG.

9. The method for preparing benzylamine according to claim 8, characterized in that... The reaction conditions in the fixed-bed hydrogenation reactor are: reaction temperature 70-100℃, benzonitrile mass hourly space velocity (WHSV) 0.4-1.2 h⁻¹. -1 The molar ratio of hydronitrogen to nitrile is 10-100:1, and the reaction pressure is 1-3 MPaG.

10. The method for preparing benzylamine according to claim 4, characterized in that... The solvent is selected from at least one of ethanol, methanol, isopropanol, n-butanol, n-pentane, liquid ammonia, toluene, ethylbenzene, benzylamine, acetonitrile, and ammonia water.