CN110143883B - Hydrogenation reaction method - Google Patents
Hydrogenation reaction method Download PDFInfo
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- CN110143883B CN110143883B CN201910450784.0A CN201910450784A CN110143883B CN 110143883 B CN110143883 B CN 110143883B CN 201910450784 A CN201910450784 A CN 201910450784A CN 110143883 B CN110143883 B CN 110143883B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
- B01J8/082—Controlling processes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
- B01J8/085—Feeding reactive fluids
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
- B01J8/087—Heating or cooling the reactor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
- B01J8/10—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles moved by stirrers or by rotary drums or rotary receptacles or endless belts
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
- C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
- C07C209/36—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00106—Controlling the temperature by indirect heat exchange
- B01J2208/00168—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles
- B01J2208/00212—Plates; Jackets; Cylinders
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
Abstract
The invention relates to the technical field of fine chemical production, and discloses a hydrogenation reaction method. The hydrogenation reaction method comprises the following steps: a preparation stage (S10) which comprises a step of adding raw materials and a catalyst into the hydrogenation kettle (1) and a step of introducing steam into a jacket (3) of the hydrogenation kettle; a reaction stage (S20) comprising a step of introducing hydrogen into the hydrogenation kettle (1) through the multifunctional pipe (4) and a step of introducing a cooling medium into a cooling pipeline arranged inside the hydrogenation kettle (1); and (S30) ending the stage, stopping adding the hydrogen after the reaction is carried out for a period of time, introducing nitrogen into the hydrogenation kettle (1) for pressing, and discharging the reaction product to the outside from a hydrogenation liquid discharge pipe (29) connected with the multifunctional pipe (4). The hydrogenation reaction method provided by the invention has the advantages of stable temperature control, improvement of the conversion rate and purity of products, prolongation of the service life of noble metal catalysts, reduction of the labor intensity of workers, reduction of energy consumption, higher automation degree and high system safety.
Description
Technical Field
The invention relates to the technical field of fine chemical production, in particular to a hydrogenation reaction method for producing intermediates such as 3, 4-dichloroaniline and the like used for pesticides, dyes, medicines and the like.
Background
In the field of fine chemicals such as agricultural chemicals, dyes and medicines, it is necessary to obtain a reduced product by hydrogenation, and for example, 3, 4-dichloroaniline is a product obtained by reacting 3, 4-dichloronitrobenzene with hydrogen gas, and is mainly used in the agricultural chemical industry for synthesizing herbicides such as diuron, in the dye industry for synthesizing azo dyes, and in the pharmaceutical industry for synthesizing bactericides and the like.
At present, the synthesis reaction of 3, 4-dichloroaniline is completed in a hydrogenation kettle, and the reaction process is as follows: conveying 3, 4-dichloronitrobenzene to a head tank for metering, then placing the product into a hydrogenation kettle, starting stirring, manually adding a noble metal catalyst, replacing air in the hydrogenation kettle with nitrogen, introducing steam into a jacket of the hydrogenation kettle after replacement is finished, and closing the steam when materials in the kettle reach 90 ℃. And then, introducing hydrogen from a hydrogen inlet at the bottom of the hydrogenation kettle to carry out hydrogenation reaction. In the process of introducing hydrogen, the adding amount of the hydrogen is controlled, and cooling water is injected into a jacket of the hydrogenation kettle to reduce the temperature so as to control the reaction temperature. After the reaction is finished, discharging from a discharge hole at the bottom of the hydrogenation kettle, conveying to a filtering system, filtering the hydrogenation liquid, taking out the noble metal catalyst, putting into the hydrogenation kettle for recycling, and conveying the product mother liquid to a refining process.
However, the following problems exist in the whole reaction process:
1. in the process of adding hydrogen for reaction, the temperature and the pressure in the hydrogenation kettle are controlled by adding steam or cooling water into the jacket of the hydrogenation kettle, the heat exchange effect is poor, the temperature is unstable and is not easy to control, the conversion rate and the purity of the product are influenced, and the safety of the system is reduced.
2. The method of adding hydrogen into the bottom of the hydrogenation kettle is not beneficial to maintenance and operation, and the added hydrogen is not uniformly distributed, so that the efficiency of hydrogenation reaction is influenced, the consumption of hydrogen is increased, and the benefit is reduced.
3. When the reaction product is discharged from the bottom of the hydrogenation kettle, the reaction product is required to be filtered in each batch, the noble metal catalyst is taken out from the filter and then put into the hydrogenation kettle for recycling, the loss of the noble metal catalyst is increased, the service life of the noble metal catalyst is shortened, and meanwhile, the process usually adopts manual feeding, so that the labor intensity of workers is increased, the requirement of closed production cannot be met, and the safety of the system is reduced.
Therefore, there is a need to provide a hydrogenation reaction process that can solve the problems as described above.
Disclosure of Invention
The invention aims to provide a hydrogenation reaction method which has the advantages of fast heat transfer, stable temperature control, realization of self-circulation of a heat exchange medium, energy saving, more uniform mixing of hydrogen and materials, fast mass transfer, reduction of hydrogen consumption, improvement of product conversion rate and purity, prolongation of the service life of a noble metal catalyst, reduction of the loss of the noble metal catalyst, achievement of the requirement of closed production, reduction of labor intensity of workers, higher automation degree, easy operation and control and improvement of system safety.
In order to achieve the above object, one aspect of the present invention provides a hydrogenation reaction method, including: a preparation stage, wherein the preparation stage comprises a step of adding raw materials and a catalyst into a hydrogenation kettle and a step of introducing steam into a jacket of the hydrogenation kettle; a reaction stage, wherein the reaction stage comprises a step of introducing hydrogen into the hydrogenation kettle through a multifunctional pipe and a step of introducing a cooling medium into a cooling pipeline arranged inside the hydrogenation kettle; and at the end stage, after the reaction is carried out for a period of time, stopping adding the hydrogen, introducing nitrogen into the hydrogenation kettle for pressing, and discharging a reaction product to the outside from a hydrogenation liquid discharge pipe connected with the multifunctional pipe.
Preferably, the cooling medium is methanol.
Preferably, the hydrogenation method further comprises the step of conveying the methanol steam passing through the cooling pipeline to a condenser to be condensed into liquid methanol, and then introducing the liquid methanol into the cooling pipeline again.
Preferably, the temperature of the liquid methanol entering the cooling pipeline is kept in the range of 60-70 ℃.
Preferably, in the reaction stage, the temperature in the hydrogenation kettle is kept in the range of 90-100 ℃ by controlling the flow rate of the cooling medium.
Preferably, in the reaction stage, the pressure in the hydrogenation kettle is kept in the range of 0.7-1.2 MPa by controlling the flow rate of the hydrogen.
Preferably, the preparation stage further comprises the step of stirring the raw material after adding the raw material and the catalyst into the hydrogenation kettle.
Preferably, the preparation stage further comprises the step of performing vacuum treatment on the inside of the hydrogenation kettle after stirring the raw material.
Preferably, the vacuum treatment of the interior of the hydrogenation kettle comprises vacuumizing and introducing nitrogen into the hydrogenation kettle.
Preferably, in the reaction stage, the end of the multifunctional pipe is provided with a distributor to disperse the hydrogen into the hydrogenation kettle.
The hydrogenation reaction method provided by the invention has the advantages of fast heat transfer, stable temperature control, realization of self circulation of a heat exchange medium, energy saving, more uniform mixing of hydrogen and materials, fast mass transfer, reduction of hydrogen consumption, improvement of product conversion rate and purity, reduction of energy consumption, prolongation of the service life of the noble metal catalyst, reduction of the loss of the noble metal catalyst, achievement of the requirement of closed production, reduction of labor intensity of workers, higher automation degree, easiness in operation and control and high system safety.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow diagram of a hydrogenation reaction process according to the present invention;
FIG. 2 is a schematic view of the structure of a hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied;
FIG. 3 is a schematic diagram of the structure of a hydrogenation reactor of a hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied;
FIG. 4 is a schematic view showing the structure of a cooling unit of a hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied;
FIG. 5 is a schematic diagram of the structure of a distributor of a hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied.
Description of the reference numerals
1, a hydrogenation kettle; 2, a stirrer; 3, jacket of hydrogenation kettle; 4, a multifunctional pipe;
5, a distributor; a main tube 51; 52 branch pipes;
6 a microporous filter; 7 hydrogen regulating valve; 8, a cooling medium adjusting valve;
9 cooling the calandria; 10 a condenser; 11 elevated tanks; 12, a lower ring pipe;
13, an upper ring pipe; 14 top ring pipes; 15 cooling medium manifold; 16 stand pipes;
21 a feeding pipe; 22 a hydrogenation tube; 23 vacuum tubes; 24 emptying the pipe;
251 a cooling water inlet pipe; 252 rows of cooling water pipes;
261 feeding a steam pipe; 262 discharging steam condensate pipes;
27 a discharge conduit; 28, introducing a cooling medium; 29 product discharge pipe;
a 30 nitrogen gas pipe; 31 emergency release pipe
A, a feed inlet; b, a hydrogenation port;
c, a vacuum port; d, emptying the air;
e1, a steam inlet; e2 steam outlet;
an F1 cooling water inlet; an F2 cooling water outlet;
g, a discharge port; h, a water inlet; j product discharge port;
k a cooling medium discharge port; l a cooling medium inlet; m nitrogen port; n Emergency relief vent
S10 preparation phase
S20 reaction stage
S30 end stage
Detailed Description
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in explaining the present invention, in a case where it is judged that explanations of related well-known functions or structures may unnecessarily obscure the gist of the present invention, detailed explanations thereof will be omitted.
Fig. 1 is a flow chart of a hydrogenation reaction method according to the present invention, fig. 2 is a schematic structural view of a hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied, fig. 3 is a schematic structural view of a hydrogenation tank of the hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied, fig. 4 is a schematic structural view of a cooling unit of the hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied, and fig. 5 is a schematic structural view of a distributor of the hydrogenation reaction system to which the hydrogenation reaction method of the present invention is applied.
In the following description of the hydrogenation method provided by the present invention, in order to make the hydrogenation method of the present invention more clear and detailed, a preferred embodiment of the hydrogenation system will be described.
As shown in fig. 1, the hydrogenation reaction method provided by the present invention includes a preparation stage S10, a reaction stage S20, and an end stage S30.
The preparation stage S10 includes a step of adding a raw material and a catalyst into the hydrogenation reactor 1 and a step of introducing steam into the hydrogenation reactor jacket 3.
The preparation step S10 is a material adding step before the hydrogenation reaction, and as shown in fig. 2 and fig. 3, a feeding port a is provided on the cover of the hydrogenation reactor 1, a feeding pipe 21 is connected to the feeding port a, a valve may be provided on the feeding pipe 21 to adjust the feeding speed of the raw material, and the raw material and the catalyst are added into the hydrogenation reactor 1 through the feeding pipe 1.
On the basis, a hydrogenation kettle jacket 3 is arranged on the outer wall of the hydrogenation kettle 1, the hydrogenation kettle jacket 3 comprises a first opening arranged at the upper part of the hydrogenation kettle jacket 3 and a second opening arranged at the lower part of the hydrogenation kettle jacket 3, the first opening is used as a steam inlet E1 and a cooling water outlet F2, a steam inlet pipe 261 and a cooling water outlet pipe 252 are connected in parallel to the first opening, the second opening is used as the steam outlet E2 and the cooling water inlet F1, and a steam condensation water outlet pipe 262 and a cooling water inlet pipe 251 are connected in parallel to the second opening. Through hydrogenation cauldron jacket 3, let in steam so that 1 inside reaction temperature that reaches of hydrogenation cauldron for the reactant effectively reacts, perhaps can let in cooling water, with cooling hydrogenation cauldron 1 on the outer wall of hydrogenation cauldron 1, thereby absorb the heat of giving off among the reaction sequence. That is, the jacket 3 of the hydrogenation vessel is used for introducing steam to heat the hydrogenation vessel in the preparation stage S10, and cooling water may be added to cool the hydrogenation vessel in the reaction stage S20 described below. In addition, since the hydrogenation reaction is an exothermic reaction, in the step of introducing steam into the hydrogenation kettle jacket 3, when the inside of the hydrogenation kettle 1 reaches a predetermined temperature (for example, 90 ℃), the introduction of steam is stopped.
The preparation stage S10 may further include a step of stirring the raw material after adding the raw material and the catalyst to the hydrogenation vessel 1. For this reason, hydrogenation cauldron 1 is inside to be provided with agitator 2 to stir reaction mass, make reaction mass and hydrogen abundant contact reaction, improve reaction efficiency and productivity. The stirrer 2 is connected with a driving source M arranged outside the hydrogenation kettle 1 so as to stir reaction substances at a constant speed or at a variable speed. In addition, the stirrer 2 is preferably disposed between an upper loop 12 and a lower loop 13 described below so that the reaction mass is in sufficient contact with the cooling circuit to exchange heat. The stirrer is preferably a disk turbine type stirrer, which causes highly turbulent radial flow when rotating, and has high stirring efficiency, so that the reaction substance has sufficient time to exchange heat with the cooling medium in the cooling pipeline.
The preparation stage S10 may further include a step of subjecting the inside of the hydrogenation tank 1 to vacuum treatment after stirring the raw material. For this reason, be provided with vacuum port C on hydrogenation cauldron 1's the kettle cover, be connected with vacuum tube 23 on this vacuum port C, carry out evacuation processing through vacuum tube 23 to hydrogenation cauldron 1 is inside to also can let in nitrogen gas through nitrogen gas pipe 30, in order to replace the air in hydrogenation cauldron 1, through vacuum treatment, can avoid oxygen in the air to participate in the reaction and influence the productivity.
The reaction stage S20 comprises a step of introducing hydrogen into the hydrogenation kettle 1 through the multifunctional pipe 4 and a step of introducing a cooling medium into a cooling pipeline arranged inside the hydrogenation kettle 1.
In order to add hydrogen into the hydrogenation kettle 1, a hydrogenation port B is arranged on a kettle cover of the hydrogenation kettle 1, a hydrogenation pipe 22 is connected to the hydrogenation port B, a multifunctional pipe 4 is arranged in the hydrogenation kettle 1, one end of the multifunctional pipe 4 is connected with the hydrogenation pipe 22, and the other end of the multifunctional pipe extends to the bottom of the hydrogenation kettle 1. In the reaction stage S20, hydrogen gas is fed into the interior of the hydrogenation vessel 1 through the hydrogenation tube 22 and the multi-functional tube 22.
In addition, a cooling line is provided inside the hydrogenation reactor 1 to perform the reaction stage S20. The cooling line as a pipe for flowing the cooling medium may be in various forms, and the present invention preferably adopts the following configuration. As shown in fig. 2 to 5, the cooling line includes a cooling rack pipe 9, a lower ring pipe 12, an upper ring pipe 13, and a riser pipe 16 (a part of the riser pipe is located outside the hydrogenation reactor), the lower ring pipe 12 and the upper ring pipe 13 are respectively connected to the lower end and the upper end of the cooling rack pipe 9, the upper ring pipe 13 is connected to a plurality of riser pipes 16, and the plurality of riser pipes 16 extend to the outside of the hydrogenation reactor 1 through a cooling medium discharge port K and communicate with the condenser 10. The cooling pipes 9 are pipes formed by combining a plurality of groups of thin pipes, which may be arranged in a square or circular shape, but not limited thereto, each group of thin pipes includes a plurality of thin pipes. The lower ring pipe 12 enables the liquid cooling medium to be uniformly distributed along the horizontal direction, the upper ring pipe 13 enables the gaseous cooling medium to be collected, the gaseous pressure is balanced, the vertical pipe 16 is connected with the cooling medium main pipe 15 of the upper ring pipe 13, and the cooling medium is discharged to the outside of the hydrogenation kettle.
The cooling pipes 9 and the plurality of vertical pipes 16 are vertically arranged to vertically cool the reaction materials, and the upper and lower loops 13 and 12 are horizontally arranged to horizontally cool the reaction materials, thereby cooling the reaction materials in all directions.
In addition, the cooling circuit may also include a top annulus 14, the top annulus 14 connecting a plurality of risers 16 in a horizontal orientation. It should be noted here that, in the hydrogenation reactor 1, there are a liquid phase portion and a gas phase portion above the liquid phase, and the top loop 14 is preferably disposed in the gas phase portion, so as to cool the gas phase portion, and facilitate the gas phase pressure balance of the cooling medium, and the uniform distribution of the cooling medium. .
In the invention, the reaction substance is cooled by introducing the cooling substance into the cooling pipeline arranged in the hydrogenation kettle, so that the cooling effect is very good. In the present invention, methanol is selected as the cooling medium. In the embodiment of preparing 3, 4-dichloroaniline by the hydrogenation reaction method of the present invention, the melting point of 3, 4-dichloronitrobenzene as a raw material is 39 to 41 ℃, the melting point of 3, 4-dichloroaniline is 69 to 71 ℃, and the boiling point of methanol at normal pressure is 64.7 ℃, in the reduction reaction, methanol is used as a cooling medium, and methanol is gasified to absorb heat, thereby achieving a good cooling effect. However, the present invention is not limited to the type of cooling medium, and other cooling substances may be used.
In addition, the hydrogenation method of the present invention may further include a step of feeding the methanol vapor after passing through the cooling line to the condenser 10 to be condensed into liquid methanol, and then, introducing the liquid methanol into the cooling line again.
The condenser 10 may be an evaporative condenser, the gaseous cooling medium delivered through the cooling medium manifold 15 enters the tube side portion of the condenser 10, and the shell side portion of the condenser 10 is introduced with cooling water through the water inlet H to condense the gaseous cooling medium into a liquid state, so that the liquid cooling medium enters the hydrogenation kettle 1 again for cooling operation. The condenser 10 may be provided with a liquid level detection and water inlet switch valve and the like and interlocked to control the liquid level.
In order to prevent excessive condensation of the reaction substance while cooling the reaction substance by heat absorption through gasification of the liquid methanol after the liquid methanol is introduced into the cooling line, it is preferable that the temperature of the liquid methanol introduced into the cooling line is maintained in the range of 60 to 70 ℃. In addition, the pressure of the liquid methanol entering the cooling pipeline can be normal pressure or micro-positive pressure.
In addition, in order to realize the self-circulation of the cooling medium, the hydrogenation reaction system may further include a head tank 11, one end of the head tank 11 is connected to the outlet of the condenser 10, and the other end of the head tank 11 is connected to the inlet of the cooling pipeline, for example, as shown in fig. 2 and 3, the inlet L of the cooling pipeline is connected to the other end of the head tank 11 through a cooling medium inlet pipe 28, and the cooling medium inlet pipe 28 is provided with a cooling medium regulating valve 8 to regulate the introduction amount of the cooling medium, so that the cooling effect can be effectively controlled. A temperature detector, a pressure detector, and the like may be provided on the head tank 11 to detect the temperature and pressure of the cooling medium in the head tank, and a safety relief port, a safety valve, and an emergency relief valve may be provided, so that the head tank 11 can be safely controlled.
Based on this, the working process of the cooling medium (exemplified by methanol) is as follows: referring to fig. 2, 3 and 5, after liquid methanol is introduced into the cooling pipeline through the cooling medium inlet L, the liquid methanol enters the lower ring pipe 12 and is uniformly distributed in the horizontal direction, and then enters each thin pipe of the cooling calandria 9 along the vertical direction to absorb heat of reaction substances near the cooling calandria 9 in the vertical direction, the liquid methanol after heat absorption is heated and gasified, the gaseous methanol is collected in the upper ring pipe 13, then enters a plurality of vertical pipes 16 and then is converged into the cooling medium header pipe 15, and then is conveyed to the condenser 10, after the gaseous methanol is cooled and condensed into a liquid state again after passing through the condenser 10, the liquid methanol enters the elevated tank 11 and is sent into the cooling pipeline in the hydrogenation kettle 1 again through the cooling medium inlet pipe 28 by utilizing a head difference, thereby completing one cycle of methanol. In the process, because methanol gasification absorbs heat, a plurality of channels are arranged on the cooling pipeline in the horizontal and vertical directions, compared with the previous cooling process through the hydrogenation kettle jacket 3, the cooling efficiency is improved, and the cooling effect can be more effectively and finely controlled by controlling the introduction amount of the methanol. The hydrogenation reaction method has the advantages of fast heat transfer, small temperature difference in the hydrogenation kettle, stable temperature control, energy conservation due to self-circulation of the heat exchange medium and the like.
In the reaction stage S20, in order to ensure high productivity, it is preferable that the temperature in the hydrogenation reactor 1 is maintained in the range of 90 to 100 ℃ by controlling the flow rate of the cooling medium, and the pressure in the hydrogenation reactor 1 is maintained in the range of 0.7 to 1.2MPa by controlling the flow rate of the hydrogen gas. However, the above range may be adjusted depending on the type of the reaction substance. Under the condition, the conversion rate and the purity of the product are very high.
The finishing stage S30 is a step of discharging the product to the outside of the hydrogenation vessel. After the hydrogenation reaction is carried out for a period of time, the hydrogen addition is stopped, and nitrogen is introduced into the hydrogenation kettle 1 to press the hydrogen, so that the reaction product is discharged to the outside from a hydrogenation liquid discharge pipe 29 connected to the multifunctional pipe 4.
In the ending step S30, in order to feed nitrogen into the hydrogenation reactor 1 for pressing, a nitrogen port M is further provided on the cover of the hydrogenation reactor 1, and the nitrogen port M is connected to a nitrogen pipe 30. And a product discharge port J is provided on the side wall of the hydrogenation reactor 1, and a product discharge pipe 29 is connected to the multi-function pipe 4 through the product discharge port J.
As shown in fig. 2, a multifunctional pipe 4 is further disposed inside the hydrogenation reactor 1, one end of the multifunctional pipe 4 is connected to the hydrogenation pipe 22, the other end is provided with a distributor 5 and a microporous filter 6, and a product discharge pipe 29 is connected to the multifunctional pipe 4 through a product discharge port J. In fact, the multi-function tube 4 is an extension of the hydrogenation tube 22 extending to the inside of the hydrogenation reactor 1 (of course, the multi-function tube 4 may be a separate pipe connected to the hydrogenation tube 22), and this portion is named the multi-function tube 4 because this pipe is used not only for passing hydrogen into the inside of the hydrogenation reactor 1 but also for discharging the product after the hydrogenation reaction is completed in the present invention. Specifically, during the reaction, hydrogen is discharged to the reaction substance through the hydrogenation tube 22, the multi-functional tube 4, and the distributor 5 in order to participate in the reaction, after the reaction is completed, the hydrogen control valve 7 provided on the hydrogenation tube 22 is closed, then nitrogen is introduced from the nitrogen port M to perform nitrogen substitution, nitrogen is introduced to press the product, the product is pressed into the multi-functional tube 4 from the microporous filter 6 and the distributor 5, and then the product is discharged to the refining process through the product discharge tube 29. In addition, the noble metal catalyst is retained by the micro-porous filter 6 for the next reaction.
In the invention, the hydrogen is introduced from the upper part of the hydrogenation kettle, thereby being beneficial to maintenance and operation, and the pipeline for introducing the hydrogen is also used as a channel for discharging the product, so that the noble metal catalyst does not need to be discharged from the bottom of the hydrogenation kettle as before, but the product is only discharged through the product discharge pipe 29 arranged at the side part of the hydrogenation kettle 1, thereby prolonging the service life of the noble metal catalyst, reducing the link of manual feeding and greatly reducing the labor intensity. And all processes can be carried out in a closed environment, so that the safety of the system is improved.
In consideration of the floating property of the gas, it is preferable that the end of the multi-functional pipe 4 provided with the distributor 5 extends to the bottom of the hydrogenation reactor 1, whereby hydrogen is introduced into the bottom of the hydrogenation reactor 1 so that the hydrogen is sufficiently contacted with the reaction substance to carry out the reaction.
As the form of the distributor 5, the present invention is not particularly limited, and preferably, as shown in fig. 5, the distributor 5 may include one main pipe 51 and a plurality of branch pipes 52, each branch pipe 52 being provided with a hydrogen gas discharge port. The length of the plurality of branch pipes 52 is gradually decreased from the center toward both ends, and the number of hydrogen gas discharge ports provided in each branch pipe 52 may be designed according to the length of the branch pipe 52. Through distributor 5, hydrogen can evenly spread inside hydrogenation cauldron 1, and hydrogen and material mix more evenly, and the mass transfer is fast, has reduced hydrogen consumption, has improved product conversion rate and purity simultaneously.
On this basis, it is preferable that a hydrogen gas discharge port be provided on the lower surface of branch pipe 52, whereby hydrogen gas can be discharged downward so as to come into contact with the reaction substance as much as possible from the bottommost portion of hydrogenation vessel 1.
In addition, in order to prevent the noble metal catalyst from entering the multi-functional pipe 4 through the hydrogen discharge port during the discharge of the product, it is preferable that a micro-porous filter 6 is provided on the hydrogen discharge port. The pore diameter of the microporous filter 6 is determined by the particle diameter smaller than that of the noble metal catalyst.
In addition, a drain port D may be further disposed on the kettle cover of the hydrogenation kettle 1, the drain port D is connected to the drain pipe 24 (an emergency drain pipe 31 may also be disposed to serve as an emergency (safety) drain port N), and when an abnormal condition (for example, an excessive pressure) occurs inside the hydrogenation kettle 1, the drain port D may be drained in an emergency. In addition, hydrogenation cauldron 1 bottom is provided with bin outlet G, is connected with row material pipe 27 on this bin outlet G, through this row material pipe 27, can discharge noble metal catalyst or the material of releasing.
In addition, the hydrogenation reaction system may further include a control unit capable of controlling the reaction temperature, pressure, etc. of the hydrogenation reactor 1 and may realize emergency shutdown. Specifically, the temperature, pressure, liquid level, hydrogen addition and other parameters of the materials in the hydrogenation kettle 1; the running, current and fault signal parameters of the motor of the stirrer 2; water level parameters of the condenser 10; various parameters such as temperature, pressure, liquid level parameters and the like of the head tank 11 can be connected to the control unit. For example, the temperature of the material in the hydrogenation kettle and the cooling medium regulating valve 8 can be controlled in an interlocking manner to regulate the flow of the cooling medium; the hydrogen flow and the hydrogen regulating valve 7 can be controlled in an interlocking way to regulate the hydrogen flow; the internal pressure of the hydrogenation kettle 1 and the emptying valve can be controlled in a linkage manner, and when the internal pressure of the kettle is overhigh, the control unit controls to open the emptying valve so as to discharge gas in the kettle.
In addition, for the safety of the system, the hydrogenation reaction system can be provided with a Safety Instrument System (SIS), and the starting conditions of logic units are as follows:
a. the temperature of the hydrogenation kettle reaches a high limit;
b. the pressure of the hydrogenation kettle reaches a high limit;
c. a hydrogenation kettle stirring motor fails;
d. the emergency stop system is manually depressed.
In one of the above situations, the SIS logic initiates all of the following actions:
1. a hydrogen switch valve is cut off in a linkage manner;
2. a cooling water inlet valve and a drain valve on a pipeline connected with a hydrogenation kettle jacket are opened in a linkage manner, so that cooling water is introduced into the hydrogenation kettle jacket;
3. the emergency vent valve is opened in a linkage manner.
Therefore, when an emergency occurs, safety accidents are avoided.
In conclusion, the hydrogenation reaction system using the hydrogenation reaction method has the advantages of fast heat transfer, stable temperature control, realization of self circulation of heat exchange medium, energy conservation, more uniform mixing of hydrogen and materials, fast mass transfer, reduction of hydrogen consumption, improvement of product conversion rate and purity, prolongation of the service life of the noble metal catalyst, reduction of the loss of the noble metal catalyst, achievement of the requirement of closed production, reduction of labor intensity of workers, higher automation degree, easiness in operation and control, high system safety and the like.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, numerous simple modifications can be made to the technical solution of the invention, including combinations of the individual specific technical features in any suitable way. The invention is not described in detail in order to avoid unnecessary repetition. Such simple modifications and combinations should also be considered as disclosed in the present invention, and all such modifications and combinations are intended to be included within the scope of the present invention.
Claims (9)
1. A method for preparing 3, 4-dichloroaniline from 3, 4-dichloronitrobenzene through hydrogenation reaction, which is characterized in that the hydrogenation reaction method comprises the following steps:
a preparation stage (S10), wherein the preparation stage (S10) comprises a step of adding raw materials of 3, 4-dichloronitrobenzene and a noble metal catalyst into a hydrogenation kettle (1) and a step of introducing steam into a hydrogenation kettle jacket (3);
a reaction stage (S20), wherein the reaction stage (S20) comprises a step of introducing hydrogen into the hydrogenation kettle (1) through a multifunctional pipe (4) and a step of introducing a cooling medium into a cooling pipeline arranged inside the hydrogenation kettle (1), the cooling pipeline comprises a cooling pipe array (9), a lower ring pipe (12), an upper ring pipe (13) and vertical pipes (16), the lower ring pipe (12) and the upper ring pipe (13) are respectively connected with the lower end and the upper end of the cooling pipe array (9), the upper ring pipe (13) is connected with a plurality of vertical pipes (16), the vertical pipes (16) extend to the outside of the hydrogenation kettle (1), the cooling pipeline further comprises a top ring pipe (14), and the top ring pipe (14) is connected with the vertical pipes (16) along the horizontal direction; the hydrogenation kettle (1) comprises a liquid phase part and a gas phase part above the liquid phase part, and the top ring pipe (14) is arranged in the gas phase part; the cooling medium is methanol; one end of the multifunctional pipe (4) is connected with the hydrogenation pipe (22), and the other end is provided with a distributor (5) and a microporous filter (6);
and a finishing stage (S30), after the reaction is carried out for a period of time, stopping adding hydrogen, introducing nitrogen into the hydrogenation kettle (1) for pressing, and discharging a reaction product to the outside from a hydrogenation liquid discharge pipe (29) connected with the multifunctional pipe (4), wherein the hydrogenation liquid discharge pipe (29) is arranged at the side part of the hydrogenation kettle (1).
2. The method for preparing 3, 4-dichloroaniline from 3, 4-dichloronitrobenzene hydrogenation reaction according to claim 1, wherein the hydrogenation method further comprises the step of conveying methanol vapor after passing through the cooling line to a condenser (10) to be condensed into liquid methanol, and then introducing the liquid methanol into the cooling line again.
3. The process for preparing 3, 4-dichloroaniline from 3, 4-dichloronitrobenzene hydrogenation according to claim 2, wherein the temperature of the liquid methanol entering the cooling line is maintained in the range of 60 to 70 ℃.
4. The process for the preparation of 3, 4-dichloroaniline from the hydrogenation of 3, 4-dichloronitrobenzene according to claim 1, wherein the temperature in the hydrogenation vessel (1) is maintained in the range of 90 to 100 ℃ in the reaction stage (S20) by controlling the flow rate of the cooling medium.
5. The process for preparing 3, 4-dichloroaniline from 3, 4-dichloronitrobenzene hydrogenation according to claim 1, characterized in that in the reaction stage (S20), the pressure in the hydrogenation vessel (1) is maintained in the range of 0.7 to 1.2MPa by controlling the flow rate of the hydrogen.
6. The process for preparing 3, 4-dichloroaniline from 3, 4-dichloronitrobenzene hydrogenation according to claim 1, wherein the preparation stage (S10) further comprises a step of stirring the raw material 3, 4-dichloronitrobenzene and noble metal catalyst after the raw material is added to the hydrogenation vessel (1).
7. The process for the preparation of 3, 4-dichloroaniline from the hydrogenation of 3, 4-dichloronitrobenzene according to claim 6, wherein the preparation stage (S10) further comprises a step of subjecting the interior of the hydrogenation vessel (1) to vacuum treatment after stirring the feed.
8. The method for preparing 3, 4-dichloroaniline from 3, 4-dichloronitrobenzene hydrogenation according to claim 7, wherein the vacuum treatment of the interior of the hydrogenation kettle (1) comprises vacuumizing and introducing nitrogen into the hydrogenation kettle (1).
9. The process for the preparation of 3, 4-dichloroaniline from the hydrogenation of 3, 4-dichloronitrobenzene according to claim 1, characterized in that in the reaction stage (S20) a distributor (5) is provided at the end of a multifunctional tube (4) for dispersing the hydrogen into the hydrogenation vessel (1).
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