A method for preparing aniline by liquid phase hydrogenation of nitrobenzene

Abstract

This invention provides a method for producing aniline from nitrobenzene via liquid-phase hydrogenation. The method includes a main reactor, a protective reactor, and a purification system. The main reactor consists of a reaction section and a purification section. The raw material undergoes hydrogenation in the reaction section of the main reactor. The gaseous output from the reaction section is washed to remove heavy components in the purification section, then condensed and separated into liquid and liquid phases. The separated liquid phase is fed into a distillation column to obtain the aniline product. The liquid phase output from the reaction section continues hydrogenation in the protective reactor, and a portion of the liquid phase is then collected through solid-liquid separation and sent to the distillation column. This method can reduce the generation of heavy component impurities by 50% and save 40% of the steam energy consumption of the purification unit.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation refining technology, and particularly relates to a method for producing aniline by liquid-phase hydrogenation of nitrobenzene. Background Technology

[0002] Aniline is an important organic synthetic raw material with wide applications in industries such as polyurethane, pharmaceuticals, pesticides, rubber additives, and resin synthesis. It is primarily used to prepare 4,4-diphenylmethane diisocyanate (MDI), a raw material for polyurethane. Currently, there are three main processes for preparing aniline: nitrobenzene Fe powder reduction, phenol ammonolysis, and nitrobenzene catalytic hydrogenation. Among these, the nitrobenzene catalytic hydrogenation method is widely used in industrial production due to its readily available raw materials, fewer steps, high production capacity, and good product yield and quality. Currently, liquid-phase hydrogenation of nitrobenzene is commonly used in industrial production.

[0003] Current nitrobenzene liquid-phase hydrogenation processes, in order to achieve high nitrobenzene conversion rates and control the low nitrobenzene content in the crude product from the reactor, result in significant over-hydrogenation byproducts in the hydrogenation reactor. This necessitates the consumption of large amounts of steam in the downstream distillation unit to control the quality of the aniline product. Conventional distillation units employ a double distillation column. The specific double distillation column process is as follows: crude aniline obtained after the nitrobenzene hydrogenation product from the reactor separates into layers is pumped to the top of the light component removal column. The top of the column collects water, cyclohexanol, and other light components, along with a small amount of aniline. The liquid phase from the bottom of the column is sent to the product column, where refined aniline is obtained at the top. The liquid from the bottom is discharged to a residue tank. This two-column process requires obtaining the aniline product from the top of the second distillation column, resulting in very high energy consumption and significant equipment investment. Furthermore, aniline spends a long time in the high-temperature zone after passing through two columns and a reboiler, which can easily lead to problems such as thermal decomposition and oxidation of aniline.

[0004] To address the high energy consumption issue in aniline production, patent CN102381984A discloses a method for thermally integrating a continuous side-stream feed tower with a distillation and recovery tower to separate hydrogen, water, aniline, and tar. This method uses a side-stream feed distillation tower instead of the initial distillation tower in a conventional two-tower distillation process, achieving dehydration and tar removal in one step and obtaining crude aniline side streams of over 99%, which are then refined in the distillation tower to obtain aniline products of over 99.9%. However, this method still requires two towers: a side-stream tower and a distillation tower. Patent CN102408341A discloses a thermal integration process between the synthesis gas and the separation unit in the aniline synthesis and separation process based on the gas-phase hydrogenation of nitrobenzene to aniline. However, this method strongly couples the hydrogenation reaction and the separation process, resulting in complex and unreasonable operation, and still requires significant heat cooling with circulating water, failing to maximize energy savings. Patent CN102701994A discloses a process for separating and refining crude aniline, which uses a baffled tower to replace the dehydration tower and distillation tower in the traditional crude aniline distillation process. However, this method is limited by factors such as the large difference in boiling points of impurities that need to be removed in the liquid-phase hydrogenation process of nitrobenzene to aniline, and the energy-saving effect in the liquid-phase hydrogenation process is not obvious. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a process for producing aniline via liquid-phase hydrogenation of nitrobenzene. This method effectively reduces the amount of reaction byproducts, controls the quality of the crude product from the reactor, and enables the extraction of qualified aniline from the bottom of the light product removal tower, thus solving the high energy consumption problem required to extract aniline from the top of the product tower in conventional distillation processes.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] A method for producing aniline by liquid-phase hydrogenation of nitrobenzene, comprising the following process flow: Hydrogen, nitrobenzene, and catalyst are introduced into a main reactor from the bottom of an external reactor, while quench water is simultaneously introduced into the main reactor; in the reaction section of the main reactor, nitrobenzene and hydrogen react under the action of a catalyst to produce aniline; liquid phase material I containing the catalyst is collected from the liquid phase outlet of the main reactor reaction section, and continues the hydrogenation reaction in a protection reactor; liquid phase material II collected from the protection reactor is concentrated by a solid-liquid separation device; the concentrated liquid phase material II is mixed with fresh catalyst and returned to the reactor. The separated liquid phase material III is sent to the heavy component removal tower of the distillation system; the aniline-water azeotrope gaseous material I overflows from the top of the reaction section and directly enters the purification section, where it is washed and deweighted by the countercurrent liquid phase material IV, and the washed gaseous material II overflows from the top of the purification section of the reactor; the gaseous material II passes through the condenser and liquid-liquid separator in sequence to obtain the organic liquid phase material V, which is sent to the light component removal tower for purification to obtain the aniline product; the liquid phase material IV enters the reactor at the feed inlet of the purification section of the main reactor, where it is washed countercurrently to remove the heavy components in the gaseous material I, and is collected from the reactor together with the liquid phase material I.

[0008] In this invention, the main reactor is a slurry bed reactor.

[0009] In this invention, the mass ratio of the raw material nitrobenzene to hydrogen is 2:1-20:1.

[0010] In this invention, the operating pressure of the reactor is 1.0-2.5 MPaG, and the temperature is 150-260℃.

[0011] In this invention, the reactor uses one or more of the following hydrogenation catalysts: precious metal, nickel, copper, zinc, and aluminum, with precious metal hydrogenation catalysts being preferred; preferably, the catalyst concentration in the reaction liquid in the reactor is 0.2-3.0 wt%.

[0012] In this invention, the mass ratio of the liquid phase material I collected from the main reactor to the nitrobenzene feed to the reactor is 0.1-1.2; preferably, the nitrobenzene content is controlled at 0.1%-5%, more preferably 0.3%-1.0%.

[0013] In this invention, the nitrobenzene content of liquid phase material I is further reduced by passing through a protective reactor; preferably, the nitrobenzene content in liquid phase material II collected from the protective reactor is controlled to be 0-1000 ppm, more preferably 20-300 ppm.

[0014] In this invention, the operating pressure of the protective reactor is 0.7-2.3 MPaG, and the temperature is 80-230℃.

[0015] In this invention, the mass ratio of nitrobenzene to feed hydrogen in liquid phase material I is 2:1-20:1.

[0016] In this invention, the main reactor is provided with a reaction section and a purification section, the purification section being equipped with a liner; preferably, the liner is one or more of structured packing, random packing, and trays, more preferably random packing and / or trays; preferably, the purification section has 3-40 theoretical plates, more preferably 6-15; preferably, the reaction section is provided with a liquid phase outlet, and the distance from the liquid phase outlet to the liner of the purification section is in the ratio of reactor diameter to 0.3-8.0. Controlling the distance between the two can ensure the residence time of gaseous material I in this area, thereby reducing the liquid phase foam entrained in gaseous material I, which is beneficial to reducing the number of theoretical plates required in the purification section and the flow rate of liquid phase stream IV.

[0017] In this invention, liquid phase material IV is one or more of the following: aniline product from the distillation unit, liquid phase material V after liquid-liquid separation, and liquid phase material VI from the top of the deweighting tower, preferably aniline product from the distillation unit; preferably, the mass ratio of liquid phase material IV to nitrobenzene is 0.1-1.2, more preferably 0.2-0.6; preferably, the feed temperature of liquid phase material IV is 40-250℃, more preferably 120-200℃.

[0018] In this invention, the liquid phase material II discharged from the protective reactor is separated into liquid phase material III by a solid-liquid separator, wherein the mass ratio of liquid phase material III to nitrobenzene is 0.05-0.8.

[0019] In this invention, the liquid phase material V after liquid-liquid separation enters the light component removal tower from the middle of the light component removal tower, the light component is collected from the top of the tower, and the aniline product is directly collected from the bottom of the tower.

[0020] Another object of the present invention is to provide an aniline product.

[0021] An aniline product, said aniline product being prepared by the above-described liquid-phase hydrogenation method for nitrobenzene.

[0022] Compared with the prior art, the positive effects of the present invention are as follows:

[0023] The reactor and process for the liquid-phase hydrogenation of nitrobenzene to aniline of the present invention, by controlling the concentration of nitrobenzene in the reactor and protecting the reaction conditions of the reactor, makes the process control of the hydrogenation process more flexible and reduces the amount of over-hydrogenation byproducts by more than 50%. By adding a rectification section at the top of the reactor and using liquid phase material IV, heavy components in gas phase material I can be effectively removed, so that the content of heavy components in liquid phase material V is significantly lower than that in the aniline product of existing processes. The bottom of the light component removal tower can directly collect aniline product that meets the index requirements. In the new process, the mass and heavy component content of liquid phase material III entering the heavy component removal tower are less than the feed mass and heavy component content entering the product tower in the conventional two-tower process. Therefore, its energy consumption is also significantly lower than that of the product tower in the conventional two-tower process, saving 40% of steam energy consumption compared with the traditional two-tower refining process. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow for the liquid-phase hydrogenation of nitrobenzene to aniline according to the present invention. In the diagram: 1 is the main reactor, 1-1 is the main reactor reaction section, 1-2 is the main reactor refining section, 2 is the protection reactor, 3 is the solid-liquid separator, 4 is the condenser, 5 is the liquid-liquid separator, 6 is the light phase removal tower, and 7 is the heavy phase removal tower and protection reactor. Specifically, 1-1 is the main reactor refining section, and 1-2 is the main reactor reaction section. The gaseous material II collected from the main reactor passes through the condenser and liquid-liquid separator sequentially before entering the light phase removal tower; the liquid material I collected from the main reactor passes through the protection reactor and solid-liquid separator sequentially before being sent to the heavy phase removal tower as externally collected liquid material III.

[0025] Figure 2 This is a schematic diagram of the traditional dual-tower refining process in existing technologies. Detailed Implementation

[0026] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0027] Gas chromatography analysis conditions: Agilent 7890B, column: HP-5 (30m x 530μm x 1.5μm), autosampler, injection port temperature: 280℃, septum purge flow rate: 3ml / min, split ratio: 10:1, injection volume: 0.8ul, temperature program: 50℃ held for 1min, increased to 150℃ at 5℃ / min, held for 2min, increased to 160℃ at 10℃ / min, held for 1min, increased to 200℃ at 15℃ / min, held for 0min, increased to 280℃ at 20℃ / min, held for 5min, detector: 280℃, hydrogen flow rate: 40mL / min, air flow rate: 400mL / min, make-up gas flow rate: 25mL / min.

[0028] Raw material: Nitrobenzene, purity ≥99.8%, Wanhua Chemical Group.

[0029] Raw material: Hydrogen, purity ≥99.8%, Wanhua Chemical Group.

[0030] Raw material: Aniline, purity ≥99.9%, Wanhua Chemical Group.

[0031] like Figure 1 The reaction system and process flow shown are as follows: the main reactor has a diameter of 30 mm, the reaction section height is 150 mm, and the refining section height is 60 mm. The liquid phase outlet of the main reactor is fixed, and the distance from the liquid phase outlet to the refining section packing is controlled by adjusting the installation position of the packing. The protection reactor is a stirred tank with a volume of 0.3 m³. 2 550mm in diameter.

[0032] Example 1

[0033] The main reactor's refining section is packed with random packing material of three theoretical plate heights, with a distance of 40 mm from the liquid phase outlet to the refining section packing. The main reactor uses a 0.8 wt% activated carbon-supported platinum-palladium catalyst, with a nitrobenzene / hydrogen feed mass ratio of 13:1 and a water / nitrobenzene feed mass ratio of 0.9:1. Each material is pumped into the main reactor. The reactor operates at a pressure of 1.7 MPaG and a temperature of 210℃. Aniline product (liquid phase IV) enters the main reactor via the refining section's inlet, where it is uniformly distributed and countercurrently washed by a liquid distributor to remove gaseous material I from the reactor's reaction section. The flow rate of liquid phase IV is 1.2:1 compared to the nitrobenzene feed rate, and the temperature is 180℃. Gaseous material II overflowing from the refining section passes through a condenser and then enters a chromatography column to obtain crude aniline product (liquid phase V). Crude aniline is fed into a light component removal tower. The tower operates at a pressure of 40 kPaA and a bottom temperature of 154°C to separate the light components, yielding aniline at the bottom. In the main reactor reaction section, the flow rate of externally sourced liquid material I is maintained at a mass ratio of 1.5:1 to the nitrobenzene feed. Liquid material I contains 0.1% nitrobenzene and undergoes further hydrogenation in a protective reactor. The protective reactor temperature is maintained at 100°C and the pressure at 1.2 MPaG. The mass ratio of nitrobenzene in liquid material I to hydrogen in the protective reactor feed is 13:1, and the nitrobenzene content in the collected liquid material II is controlled to be 100 ppm. After passing through a thickener, liquid material II is collected as liquid material III, with a flow rate to nitrobenzene mass ratio of 0.35:1. Liquid material III is directly fed to a heavy component removal tower. The tower operates at a pressure of 13 kPaA and a bottom temperature of 182°C to separate the heavy components, yielding aniline at the top.

[0034] The unit operated continuously and stably for two months under the above conditions. Analysis showed that the heavy component content in liquid phase material V was 36 ppm, the heavy component content in liquid phase material III was 0.41%, and the heavy component content in the aniline product was 38 ppm. The energy consumption of the light component removal tower was calculated to be 128 kW / ton of aniline product, and the energy consumption of the heavy component removal tower was 120 kW / ton of aniline product.

[0035] Example 2

[0036] The main reactor's refining section is packed with random packing material of 8 theoretical plate heights, with a distance of 60 mm from the liquid phase outlet to the refining section packing. The main reactor uses a 0.8 wt% activated carbon-supported platinum-palladium catalyst, with a nitrobenzene / hydrogen feed mass ratio of 13:1 and a water / nitrobenzene feed mass ratio of 0.9:1. Each material is pumped into the main reactor. The reactor operates at a pressure of 1.7 MPaG and a temperature of 210℃. Aniline product is used as the inlet for liquid phase material IV in the refining section of the main reactor. It is then uniformly distributed and countercurrently washed by a liquid distributor to remove gaseous material I from the reactor's reaction section. The flow rate of liquid phase material IV is 0.25:1 compared to the nitrobenzene feed rate, and the temperature is 140℃. Gaseous material II overflowing from the refining section passes through a condenser and then enters a chromatography unit to obtain crude aniline product (liquid phase material V). Crude aniline is fed into a light component removal tower. The tower operates at a pressure of 40 kPaA and a bottom temperature of 154°C to separate the light components, yielding aniline at the bottom. In the main reactor reaction section, the flow rate of externally sourced liquid material I is maintained at a mass ratio of 0.7:1 to the nitrobenzene feed. Liquid material I contains 0.4% nitrobenzene and undergoes further hydrogenation in a protective reactor. The protective reactor temperature is maintained at 80°C and the pressure at 2 MPaG. The mass ratio of nitrobenzene to hydrogen in liquid material I is 13:1, and the nitrobenzene content in the collected liquid material II is controlled to be 40 ppm. After passing through a thickener, liquid material II is collected as liquid material III, with a flow rate to nitrobenzene mass ratio of 0.28:1. Liquid material III is directly fed to a heavy component removal tower. The tower operates at a pressure of 13 kPaA and a bottom temperature of 182°C to separate the heavy components, yielding aniline at the top.

[0037] The unit operated continuously and stably for two months under the above conditions. Analysis showed that the heavy component content in liquid phase material V was 16 ppm, the heavy component content in liquid phase material III was 0.43%, and the heavy component content in the aniline product was 17 ppm. The energy consumption of the light component removal tower was calculated to be 120 kW / ton of aniline product, and the energy consumption of the heavy component removal tower was 104 kW / ton of aniline product.

[0038] Example 3

[0039] The main reactor's refining section is packed with 40 theoretically plate-high random packing materials, with a distance of 60 mm from the liquid phase outlet to the refining section packing. The main reactor uses a 3 wt% activated carbon-supported platinum-palladium catalyst. The nitrobenzene / hydrogen feed mass ratio is 13:1, and the water / nitrobenzene feed mass ratio is 0.9:1. Each material is pumped into the main reactor separately. The reactor operates at a pressure of 1.7 MPaG and a temperature of 150°C. Aniline product (liquid phase IV) enters the main reactor via the refining section's inlet and is uniformly distributed and countercurrently washed by a liquid distributor to remove gaseous material I from the reactor's reaction section. The flow rate of liquid phase IV is 0.4:1 compared to the nitrobenzene feed rate, and the temperature is 250°C. Gaseous material II overflowing from the refining section passes through a condenser and then enters a chromatography unit to obtain crude aniline (liquid phase V). Crude aniline is fed into a light component removal tower. The tower operates at a pressure of 40 kPaA and a bottom temperature of 154°C to separate the light components, yielding aniline at the bottom. In the main reactor reaction section, the flow rate of externally sourced liquid material I is maintained at a mass ratio of 0.9:1 to the nitrobenzene feed. Liquid material I contains 0.9% nitrobenzene and undergoes further hydrogenation in a protective reactor. The protective reactor temperature is maintained at 230°C and the pressure at 1.2 MPaG. The mass ratio of nitrobenzene in liquid material I to hydrogen in the protective reactor feed is 7:1, and the nitrobenzene content in the collected liquid material II is controlled to be 2 ppm. After passing through a thickener, liquid material II is collected as liquid material III, with a flow rate to nitrobenzene mass ratio of 0.23:1. Liquid material III is directly fed to a heavy component removal tower. The tower operates at a pressure of 13 kPaA and a bottom temperature of 182°C to separate the heavy components, yielding aniline at the top.

[0040] The unit operated continuously and stably for two months under the above conditions. Analysis showed that the heavy component content in liquid phase material V was 22 ppm, the heavy component content in liquid phase material III was 0.58%, and the heavy component content in the aniline product was 22 ppm. The energy consumption of the light component removal tower was calculated to be 122 kW / ton of aniline product, and the energy consumption of the heavy component removal tower was 112 kW / ton of aniline product.

[0041] Example 4

[0042] The main reactor's refining section is packed with 20 theoretically plate-high random packing materials, with a distance of 100 mm from the liquid phase outlet to the refining section packing. The main reactor uses a 0.2 wt% activated carbon-supported platinum-palladium catalyst. The nitrobenzene / hydrogen feed mass ratio is 6:1, and the water / nitrobenzene feed mass ratio is 1.1:1. Each material is pumped into the main reactor separately. The reactor operates at a pressure of 1.7 MPaG and a temperature of 260℃. Aniline product is used as the inlet for liquid phase material IV in the refining section of the main reactor. It is then uniformly distributed and countercurrently washed by a liquid distributor to remove gaseous material I from the reactor's reaction section. The flow rate of liquid phase material IV is 0.1:1 compared to the nitrobenzene feed rate, and the temperature is 40℃. Gaseous material II overflowing from the refining section passes through a condenser and then enters a chromatography column to obtain crude aniline product (liquid phase material V). Crude aniline is fed into a light component removal tower. The tower operates at a pressure of 40 kPaA and a bottom temperature of 154°C to separate the light components, yielding aniline at the bottom. In the main reactor reaction section, the flow rate of externally sourced liquid material I is maintained at a mass ratio of 0.3:1 to the nitrobenzene feed. Liquid material I contains 5% nitrobenzene and undergoes further hydrogenation in a protective reactor. The protective reactor temperature is maintained at 100°C and the pressure at 1.6 MPaG. The mass ratio of nitrobenzene in liquid material I to hydrogen in the protective reactor feed is 10:1, and the nitrobenzene content in the collected liquid material II is controlled to be 1000 ppm. After passing through a thickener, liquid material II is collected as liquid material III, with a flow rate to nitrobenzene mass ratio of 0.13:1. Liquid material III is directly fed to a heavy component removal tower. The tower operates at a pressure of 13 kPaA and a bottom temperature of 182°C to separate the heavy components, yielding aniline at the top.

[0043] The unit operated stably and continuously for two months under the above conditions. Analysis showed that the heavy component content in liquid phase material V was 33 ppm, the heavy component content in liquid phase material III was 0.97%, and the heavy component content in the aniline product was 33 ppm. The energy consumption of the light component removal tower was calculated to be 120 kW / ton of aniline product, and the energy consumption of the heavy component removal tower was 109 kW / ton of aniline product.

[0044] Comparative Example 1

[0045] Compared to the examples, the main reactor in the comparative example only includes the reaction section and does not include the purification section. The main reactor uses a platinum-palladium catalyst supported on activated carbon at a concentration of 0.8 wt%. The nitrobenzene / hydrogen feed mass ratio is 13:1, and the water / nitrobenzene feed mass ratio is 0.9:1. Each material is pumped into the main reactor separately. The reactor operates at a pressure of 1.7 barG and a temperature of 210°C. The gaseous material I overflowing from the reactor passes through a condenser and then enters a chromatography column to obtain crude aniline (liquid material V). The flow rate of liquid material I collected from the reactor is at a mass ratio of 0.45:1 to the nitrobenzene feed, and the nitrobenzene content in liquid material I is 40 ppm. After passing through a thickener, liquid material III is collected, with a flow rate at a mass ratio of 0.04:1 to nitrobenzene. Liquid material V and liquid material III are mixed and then fed into a light component removal column. The operating pressure of the light component removal column is controlled at 40 kPaA, and the bottom temperature is 154°C to separate the light components. The liquid from the bottom of the light component removal tower is sent to the product tower. The operating pressure of the product tower is controlled at 13 kPaA and the bottom temperature at 182°C to separate the heavy components. The aniline product is obtained at the top of the tower.

[0046] The unit operated continuously and stably for two months under the above conditions. Analysis showed that the heavy component content in liquid phase material V was 662 ppm, the heavy component content in liquid phase material III was 2.2%, and the heavy component content in the aniline product was 56 ppm. The energy consumption of the light component removal tower was calculated to be 120 kW / ton of aniline product, and the energy consumption of the product tower was 260 kW / ton of aniline product.

[0047] The results above show that the new process of this invention can reduce the generation of heavy component impurities in the reactor by more than 50% and the steam energy consumption of the downstream refining unit by 40%.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing aniline by liquid-phase hydrogenation of nitrobenzene, characterized in that, The method includes the following process flow: the reaction raw materials hydrogen, nitrobenzene, and catalyst enter the main reactor from the bottom of the self-reactor, while quench water is introduced into the main reactor; in the reaction section of the main reactor, the nitrobenzene and hydrogen react under the action of the catalyst to produce aniline; Liquid phase material I containing the catalyst is collected from the liquid phase outlet of the main reactor reaction section and continues to undergo hydrogenation reaction in the protection reactor. Liquid phase material II collected from the protection reactor is concentrated by the solid-liquid separation equipment. After being mixed with fresh catalyst, the concentrated liquid phase material II is returned to the reactor. The separated liquid phase material III is sent to the deweighting tower of the distillation system. Aniline-water azeotrope gaseous material I overflows from the top of the reaction section and directly enters the refining section, where it is washed and deweighted by the countercurrent liquid material IV. The washed gaseous material II overflows from the top of the refining section of the main reactor. Gaseous material II passes sequentially through a condenser and a liquid-liquid separator to obtain organic liquid material V, which is then sent to a light-weight removal tower for refining to obtain aniline product. Liquid material IV enters the reactor at the feed inlet of the main reactor refining section, where it is countercurrently washed to remove heavy components from gaseous material I, and is collected from the reactor together with liquid material I. The nitrobenzene content in the reactor feed is 0.1%-5%; The operating pressure of the protective reactor is 0.7-2.3 MPaG, and the temperature is 80-230℃.

2. The method according to claim 1, characterized in that, The main reactor is a slurry bed reactor; And / or, the mass ratio of the raw material nitrobenzene to hydrogen is 2:1-20:1; And / or, the reactor operates at a pressure of 1.0-2.5 MPaG and a temperature of 150-260℃; And / or, the reactor uses one or more of the following hydrogenation catalysts: precious metals, nickel, copper, zinc, and aluminum.

3. The method according to claim 1, characterized in that, The reactor uses a precious metal hydrogenation catalyst; The catalyst concentration in the reaction liquid in the reactor is 0.2-3.0 wt%.

4. The method according to claim 1 or 2, characterized in that, The mass ratio of the liquid phase material I collected from outside the main reactor to the nitrobenzene feed to the reactor is 0.1-1.2; The content of nitrobenzene should be controlled at 0.3%-1.0%.

5. The method according to claim 1, characterized in that, Liquid phase material I undergoes further reduction of nitrobenzene content in a protected reactor.

6. The method according to claim 5, characterized in that, Control the nitrobenzene content in the liquid phase II material collected from the reactor to be 0-1000 ppm.

7. The method according to claim 6, characterized in that, The nitrobenzene content in the liquid phase II material collected from the reactor is controlled to be 20-300 ppm.

8. The method according to claim 1, characterized in that, The mass ratio of nitrobenzene to feed hydrogen in liquid phase material I is 2:1-20:

1.

9. The method according to claim 1, characterized in that, The main reactor is equipped with a reaction section and a refining section, with the refining section having an inner liner.

10. The method according to claim 9, characterized in that, The inner lining can be one or more of the following: structured packing, random packing, and trays; The theoretical plate number for the refining section is 3-40; The reaction section is equipped with a liquid phase outlet, and the distance from the liquid phase outlet to the liner of the refining section is in the ratio of 0.3 to 8.0 to the reactor diameter.

11. The method according to claim 10, characterized in that, The lining is made of random packing and / or trays; The theoretical plate number for the refining section is 6-15.

12. The method according to claim 1, characterized in that, Liquid phase material IV is one or more of the following: aniline product from the distillation unit, liquid phase material V after liquid-liquid separation, and liquid phase material VI from the top of the deweighting tower.

13. The method according to claim 12, characterized in that, Liquid phase material IV is the aniline product from the distillation unit; The mass ratio of liquid phase material IV to nitrobenzene is 0.1-1.2; The feed temperature for liquid phase material IV is 40-250℃.

14. The method according to claim 13, characterized in that, The mass ratio of liquid phase material IV to nitrobenzene is 0.2-0.6; The feed temperature for liquid phase material IV is 120-200℃.

15. The method according to claim 1, characterized in that, The liquid phase material II discharged from the protective reactor is separated into liquid phase material III by a solid-liquid separator, wherein the mass ratio of liquid phase material III to nitrobenzene is 0.05-0.

8.

16. The method according to claim 1, characterized in that, After liquid-liquid separation, the liquid phase material V enters the light component removal tower from the middle of the light component removal tower. The light component is collected from the top of the tower, and the aniline product is collected directly from the bottom of the tower.

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