CN111302949B - Process for preparing phenylenediamine by microreaction technology - Google Patents
Process for preparing phenylenediamine by microreaction technology Download PDFInfo
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- CN111302949B CN111302949B CN202010282623.8A CN202010282623A CN111302949B CN 111302949 B CN111302949 B CN 111302949B CN 202010282623 A CN202010282623 A CN 202010282623A CN 111302949 B CN111302949 B CN 111302949B
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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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- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
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- C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
- C07C201/06—Preparation of nitro compounds
- C07C201/08—Preparation of nitro compounds by substitution of hydrogen atoms by nitro groups
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- C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
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Abstract
The application belongs to the technical field of fine chemical engineering, and particularly relates to a process for preparing phenylenediamine by a micro-reaction technology, which comprises the following steps: and metering the nitroaromatic hydrocarbon to be reduced, the solvent, the catalyst and hydrogen, and then continuously feeding the measured nitroaromatic hydrocarbon, the solvent, the catalyst and the hydrogen into a hydrogenation microreactor for carrying out hydrogenation reduction reaction. The nitroaromatic to be reduced can also be prepared by adopting a continuous micro-nitration process. The hydrogenation microreactor is adopted for carrying out hydrogenation reduction reaction, and the process is safe and controllable; particularly, the method is combined with a micro-nitration reactor to prepare the nitroaromatic, and the nitroaromatic directly enters a hydrogenation microreactor without separation, is a continuous production process comprising the microreactor, can prevent the accumulation of dinitrobenzene in the process, and is an intrinsically safe phenylenediamine preparation process.
Description
Technical Field
The application belongs to the technical field of fine chemical engineering, and particularly relates to a process for preparing phenylenediamine by a micro-reaction technology.
Background
The micro-reaction technology generally refers to a continuous flow reaction technology which takes a micro-reactor as a core component. The Micro-reactor (Micro-channel reactor) is a continuous flow type pipeline reactor, the size of an internal channel of the Micro-reactor is far smaller than that of a traditional conventional reactor, and the Micro-reactor has extremely high heat exchange rate, so that even if a large amount of heat is suddenly released in the reaction, the heat can be rapidly led out, and the possibility of safety accidents and quality accidents is reduced to the maximum extent.
In the traditional production of m-phenylenediamine, iron powder is used as a reducing agent, and m-dinitrobenzene is reduced to the m-phenylenediamine in an acid solution. The process is simple, the technology is mature, but the cost is high, the yield is low, and the environmental pollution is serious. The catalytic hydrogenation method is a promising method for preparing m-phenylenediamine and has the advantages of low pollution, high product yield and the like, so that the catalytic hydrogenation method is concerned. However, the catalytic hydrogenation method has the problems of more materials for instant reaction, large heat generation, easy occurrence of industrial safety accidents and the like.
Disclosure of Invention
The inventors have completed the present application in order to overcome the above disadvantages.
The application relates to a process for preparing phenylenediamine by a micro-reaction technology, which comprises the following steps: and metering the nitroaromatic hydrocarbon to be reduced, the solvent, the catalyst and hydrogen, and then continuously feeding the measured nitroaromatic hydrocarbon, the solvent, the catalyst and the hydrogen into a hydrogenation microreactor for carrying out hydrogenation reduction reaction.
And further, the reaction liquid obtained from the hydrogenation microreactor enters a hydrogenation ageing device for ageing, and the end point is determined when no nitro compound exists.
The nitroaromatic to be reduced is any one, any two or a mixture of any more of m-dinitrobenzene, o-dinitrobenzene, p-dinitrobenzene and nitrobenzene.
In the present application, the hydrogenation microreactor may be provided in a form in which two or more hydrogenation microreactors are connected in series as required.
The nitryl aromatic hydrocarbon to be reduced can be prepared by adopting a common reaction kettle or a microreactor.
In a preferred embodiment of the present application, the nitroarene to be reduced can be prepared by the following steps:
1) first-stage nitration: benzene and mixed acid continuously enter a first-stage nitration microreactor to carry out nitration reaction, and the obtained reaction liquid is aged and separated to obtain an organic phase containing nitrobenzene and a water phase containing sulfuric acid;
2) secondary nitrification: continuously feeding the organic phase containing nitrobenzene and the mixed acid obtained in the step 1) into a secondary nitrification microreactor to carry out nitrification reaction, and ageing and separating the obtained reaction liquid to obtain an organic phase containing mixed dinitrobenzene and a water phase containing sulfuric acid;
3) washing the organic phase containing the mixed dinitrobenzene obtained in the step 2) to obtain the nitroarene to be reduced.
Preferably, the molar ratio of the hydrogen to the nitroaromatic hydrocarbon added into the hydrogenation microreactor is 6-16: 1. The molar ratio of the hydrogen to the nitroarene added in the hydrogenation microreactor provided by the application can be, for example: 6-8: 1, 6-10: 1, 6-12: 1, 6-14: 1, 6-16: 1, 8-10: 1, 8-12: 1, 8-14: 1, 8-16: 1, 10-12: 1, 10-14: 1, 10-16: 1, 12-14: 1, 12-16: 1 or 14-16: 1, and further preferably 8-12: 1.
preferably, the feeding weight ratio of the nitroaromatic to be reduced, the solvent and the catalyst in the hydrogenation microreactor is 1: 1.5-4: 0.05-0.1. The feeding weight ratio of the nitroaromatic to be reduced, the solvent and the catalyst in the hydrogenation microreactor can be, for example, 1: 1.5-2: 0.05-0.1, 1: 2-4: 0.05-0.1, 1: 1.5-2: 0.05-0.07, 1: 1.5-2: 0.07-0.1, 1: 2-4: 0.07-0.1 or 1: 2-4: 0.07-0.1.
Preferably, the temperature in the hydrogenation microreactor is controlled to be 50-160 ℃ and the pressure is 0.3-10 MPa, the temperature in the hydrogenation microreactor can be controlled to be 50-80 ℃, 50-110 ℃, 50-140 ℃, 80-110 ℃, 80-140 ℃, 80-160 ℃, 110-140 ℃ or 110-160 ℃, the pressure in the hydrogenation microreactor can be controlled to be 0.3-1 MPa, 0.3-3 MPa, 0.3-6 MPa, 1-3 MPa, 1-6 MPa, 1-10 MPa, 3-6 MPa, 3-10 MPa or 6-10 MPa, and preferably, the temperature in the hydrogenation microreactor is controlled to be 80-100 ℃ and the pressure is 1-2.5 MPa.
Preferably, the catalyst may be, for example, a nickel catalyst, a palladium catalyst or a platinum catalyst, and particularly preferably, the catalyst is a nickel catalyst.
Preferably, the hydrogenation microreactor comprises a casing pipe reactor main body, the casing pipe reactor main body comprises an inner casing pipe, an intermediate casing pipe and an outer casing pipe, the intermediate casing pipe is provided with an internal thread and an external thread, the inner casing pipe is provided with micropores penetrating through the pipe wall, a spiral circulation path formed between the outer wall of the inner casing pipe and the inner wall of the intermediate casing pipe is used as a reaction channel, the inner casing pipe is used as a gas channel, and a spiral circulation path formed between the outer wall of the intermediate casing pipe and the inner wall of the outer casing pipe is used as a heat exchange medium channel.
Preferably, the outer sleeve is provided with an internal thread, the external thread of the middle sleeve and the internal thread of the outer sleeve are opposite in direction, and when viewed from one end of the microreactor, one thread rotates clockwise, and the other thread rotates counterclockwise.
Preferably, the difference between the outer diameter of the inner sleeve and the minimum radius of the inner thread of the intermediate sleeve is 1 to 3000 μm, preferably 500 to 1000 μm.
Preferably, the difference between the maximum radius of the external thread of the middle sleeve and the inner diameter of the outer sleeve is 1000-5000 μm.
In a preferred embodiment of this application, hydrogenation microreactor, including the casing pipe reactor main part, the casing pipe reactor main part includes interior sleeve pipe, middle sleeve pipe and outer tube, interior sleeve pipe is equipped with internal thread and external screw thread, be equipped with the micropore that runs through the pipe wall on the middle sleeve pipe, the spiral helicine circulation route that forms between interior sheathed tube outer wall and the middle sheathed tube inner wall is as reaction channel, interior sleeve pipe is as heat transfer media passageway, the circulation route that forms between the outer wall of middle sheathed tube and the inner wall of outer tube is as gas passage.
In the preferred embodiment, the difference between the inner diameter of the intermediate sleeve and the maximum radius of the external thread of the inner sleeve is more preferably 1 to 3000 μm, and still more preferably 500 to 1000 μm.
In the above preferred embodiment, it is further preferred that the inner diameter of the intermediate sleeve is 1000 to 5000 μm (in terms of the thread protrusion).
The diameter of the micropores is 0.1-50 μm.
More preferably, the diameter of the micropores is 5 to 15 μm.
Furthermore, the hydrogenation microreactor comprises a liquid material inlet, a liquid material outlet, a gas inlet, a gas outlet, a heat exchange medium inlet and a heat exchange medium outlet.
Preferably, the number of the liquid material inlets, the liquid material outlets, the gas inlets, the gas outlets, the heat exchange medium inlets and the heat exchange medium outlets is more than one.
Preferably, the internal thread and the external thread are trapezoidal threads, the thread height of each trapezoidal thread is 1.5-10.5 mm, and the thread pitch is 2-20 mm; further preferably, the height of the trapezoidal thread is 4.5-6.5 mm, and the thread pitch is 6 mm.
Preferably, the flow directions of the fluids in the reaction channel and the heat exchange medium channel are opposite.
Preferably, the flow directions of the reaction channel and the gas channel are the same or opposite.
Preferably, the axial center lines of the inner sleeve, the middle sleeve and the outer sleeve are overlapped, and the inner sleeve, the middle sleeve and the outer sleeve are fixed through a compression screw.
Furthermore, cover plates are respectively arranged at two ends of the inner sleeve, the middle sleeve and the outer sleeve, and are sealed through O-shaped rings.
Preferably, the catalyst, the nitroaromatic to be reduced and the solvent are mixed into a suspension, the suspension is metered and then continuously fed into the hydrogenation microreactor, and simultaneously, hydrogen is continuously fed into the hydrogenation microreactor.
Preferably, the mixed acid is a mixture of nitric acid and sulfuric acid, and the molar ratio of the nitric acid to the benzene added in the step 1) is 0.9-0.99: 1; the molar ratio of the nitric acid added in the step 2) to the benzene added in the step 1) is 0.9-0.99: 1.
Preferably, in the primary nitration microreactor, the reaction temperature is 30-75 ℃, and the residence time of reactants is 5-30 s.
Preferably, in the secondary nitration microreactor, the reaction temperature is 70-90 ℃, and the residence time of reactants is 5-30 s.
Preferably, the mixed acid added into the first-stage nitration microreactor comprises the following components in percentage by mass: 55-65% of sulfuric acid, 20-30% of nitric acid and 10-20% of water.
Preferably, the mixed acid added into the secondary nitration microreactor comprises the following components in percentage by mass: 70-85% of sulfuric acid, 10-25% of nitric acid and 5-10% of water.
Further, the washing comprises water washing and alkali washing, and the mass concentration of alkali liquor in the alkali washing is 5%.
Compared with the prior art, the process has the following beneficial effects:
(1) a hydrogenation micro-reactor is adopted for carrying out hydrogenation reduction reaction, and the process is safe and controllable;
(2) the hydrogenation microreactor adopts the spiral reaction channel, so that the collision probability of reaction materials and the inner wall of the reaction channel is increased, the collision probability of liquid materials and gas materials is also increased, and the mass transfer effect is enhanced; in the reaction process, the reaction liquid moves outwards under the action of centrifugal force, and the gas and the reaction liquid are continuously and repeatedly collided and mixed, so that the mass transfer effect is better, and the reaction is more complete;
(3) particularly, the method is combined with a micro-nitration reactor to prepare dinitroarene, and each isomer directly enters a hydrogenation micro-reactor without separation, so that the method is a continuous production process comprising the micro-reactor, can prevent the accumulation of dinitrobenzene in the process, and is an intrinsically safe phenylenediamine preparation process.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of the non-limiting embodiments with reference to the following drawings:
FIG. 1 is a longitudinal sectional view of a hydrogenation microreactor according to example 1 of the present application;
FIG. 2 is a cross-sectional view of a hydrogenation microreactor in accordance with example 1 of the present application;
FIG. 3 is an enlarged view of FIG. 1A;
FIG. 4 is a schematic diagram showing the flow and collision of reaction materials in the hydrogenation microreactor in example 1 of the present application;
FIG. 5 is a longitudinal sectional view of a hydrogenation microreactor in example 4 of this application;
reference numerals are as follows: 1-inner sleeve, 2-middle sleeve, 3-outer sleeve, 4-gas channel, 5-reaction channel, 6-heat exchange medium channel, 7-liquid material inlet, 8-liquid material outlet, 9-gas inlet, 10-gas outlet, 11-heat exchange medium inlet and 12-heat exchange medium outlet.
Detailed Description
The present application will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the present application in any way. It should be noted that various changes and modifications can be made by one skilled in the art without departing from the spirit of the application. All falling within the scope of protection of the present application.
Example 1
A process for preparing phenylenediamine by a microreaction technique comprising the steps of: and metering the nitroaromatic hydrocarbon to be reduced, the solvent, the catalyst and hydrogen, and then continuously feeding the measured nitroaromatic hydrocarbon, the solvent, the catalyst and the hydrogen into a hydrogenation microreactor for carrying out hydrogenation reduction reaction.
And (3) allowing the reaction liquid obtained in the hydrogenation microreactor to enter a hydrogenation ageing device for ageing, and detecting that the reaction liquid is at an end point when no nitro compound exists.
The nitroaromatic hydrocarbon is m-dinitrobenzene.
The molar ratio of hydrogen to m-dinitrobenzene added into the hydrogenation microreactor is 14: 1; the weight ratio of the m-dinitrobenzene to the solvent (methanol) to the catalyst (skeletal nickel) is 1: 2.5: 0.08; the temperature in the hydrogenation micro-reactor is controlled at 60 ℃ and the pressure is controlled at 7 MPa.
As shown in fig. 1 to 3, the hydrogenation microreactor includes a casing reactor main body, the casing reactor main body includes an inner casing 1, an intermediate casing 2, and an outer casing 3, the intermediate casing 2 is provided with an internal thread and an external thread, the inner casing 1 is provided with a micro-hole penetrating through a wall of the casing, a spiral circulation path formed between an outer wall of the inner casing 1 and an inner wall of the intermediate casing 2 serves as a reaction channel 5, the inner casing serves as a gas channel 4, and a spiral circulation path formed between an outer wall of the intermediate casing and an inner wall of the outer casing serves as a heat exchange medium channel 6.
The diameter of the micropores on the inner sleeve is 0.1-50 μm, in this embodiment, the diameter of the micropores on the inner sleeve is 10 μm, and the micropores are uniformly distributed on the inner sleeve.
The difference H between the outer diameter of the inner sleeve 1 and the minimum radius of the internal thread of the middle sleeve 2 is 1-3000 μm, preferably 500-1000 μm, and H in the embodiment is 1000 μm; the difference H' between the maximum radius of the external thread of the middle sleeve 2 and the inner diameter of the outer sleeve 3 is 1000-5000 μm, and H is 3000 μm in the embodiment.
The flow directions of the fluids in the reaction channel 5 and the heat exchange medium channel 6 are opposite; the flow directions of the fluids in the reaction channel 5 and the gas channel 4 are the same or opposite, and the flow directions of the fluids in the reaction channel 5 and the gas channel 4 are the same in the embodiment.
The micro-reactor suitable for gas-liquid, gas-solid two-phase or gas-liquid-solid three-phase reaction comprises a liquid material inlet 7, a liquid material outlet 8, a gas inlet 9, a gas outlet 10, a heat exchange medium inlet 11 and a heat exchange medium outlet 12. Liquid material import, liquid material export, gaseous import, gaseous export, heat transfer medium import and heat transfer medium export quantity are more than one, and liquid material import, liquid material export, heat transfer medium import and heat transfer medium export respectively set up four in this embodiment, and gaseous import and gaseous export respectively set up two.
During operation, the catalyst, the nitroaromatic to be reduced and the solvent are mixed to prepare a suspension, the suspension is sent into the hydrogenation microreactor from a liquid material inlet, the skeleton nickel and the reaction material are discharged from a liquid material outlet after reaction, and the skeleton nickel catalyst in the reaction liquid is collected through a magnetic recovery separator by utilizing the magnetism of the nickel catalyst and is used for production again.
The residual hydrogen after the reaction and the reaction materials are discharged from a liquid material outlet together (possibly a small amount of hydrogen is discharged from a gas outlet 10), and the hydrogen can be recycled and reused after gas-liquid separation.
The internal thread and the external thread of the middle sleeve are trapezoidal threads, the tooth height h of each trapezoidal thread is 1.5-10.5 mm, and h is 2.5mm in the embodiment; the pitch p is 2-20 mm, in this embodiment p is 8 mm.
The shaft center lines of the inner sleeve, the middle sleeve and the outer sleeve are overlapped, the inner sleeve, the middle sleeve and the outer sleeve are fixed through compression screws, cover plates are arranged at two ends of the inner sleeve, the middle sleeve and the outer sleeve respectively, and the two ends of the inner sleeve, the middle sleeve and the outer sleeve are sealed through O-shaped rings.
FIG. 4 is a schematic diagram showing the flow and collision of the reaction materials in the microreactor according to example 1 of the present application.
The hydrogenation microreactor has the advantages of small occupied area, easiness in processing, adoption of a cutting process for threads, adoption of laser drilling for micropores and low manufacturing cost. The thickness of the tube walls of the inner sleeve, the outer sleeve and the middle sleeve is 10-30 mm, and the tube walls can be selected according to different reaction pressures and temperatures.
The yield of the phenylenediamine product after the reaction is 99.6 percent based on the m-dinitrobenzene.
Example 2
A process for preparing phenylenediamine by a microreaction technique comprising the steps of: firstly, preparing nitro aromatic hydrocarbon to be reduced, a solvent and a catalyst into a suspension, metering the suspension, continuously feeding the suspension into a hydrogenation microreactor, and simultaneously continuously feeding hydrogen into the hydrogenation microreactor to perform continuous hydrogenation reduction reaction.
And (3) allowing the reaction liquid obtained in the hydrogenation microreactor to enter a hydrogenation ageing device for ageing, and detecting that the reaction liquid is at an end point when no nitro compound exists.
The nitroaromatic is a mixture of m-dinitrobenzene and o-dinitrobenzene, and the mass ratio of the m-dinitrobenzene to the o-dinitrobenzene is 4: 1.
The molar ratio of hydrogen to m-dinitrobenzene added into the hydrogenation microreactor is 10: 1; the weight ratio of the m-dinitrobenzene to the solvent (methanol) to the catalyst (skeleton nickel) is 1: 1.8: 0.06; the temperature in the hydrogenation micro-reactor is controlled to be 80 ℃ and the pressure is controlled to be 2 MPa.
The structure of the hydrogenation microreactor is the same as that of example 1.
The yield of the phenylenediamine product after reaction is 99.8 percent based on m-dinitrobenzene and o-dinitrobenzene.
Example 3
A process for preparing phenylenediamine by a microreaction technique comprising the steps of: firstly, preparing nitro aromatic hydrocarbon to be reduced, a solvent and a catalyst into a suspension, continuously feeding the suspension into a hydrogenation microreactor after metering, and simultaneously continuously feeding hydrogen into the hydrogenation microreactor to perform continuous hydrogenation reduction reaction.
And (3) allowing the reaction liquid obtained in the hydrogenation microreactor to enter a hydrogenation ageing device for ageing, and detecting that no nitro compound exists, wherein the end point is the end point.
The nitroaromatic hydrocarbon is a mixture of m-dinitrobenzene, p-dinitrobenzene and o-dinitrobenzene, and the mass ratio of the m-dinitrobenzene to the p-dinitrobenzene to the o-dinitrobenzene is 5:1: 2.
The molar ratio of hydrogen to m-dinitrobenzene added into the hydrogenation microreactor is 12: 1; the weight ratio of the m-dinitrobenzene to the solvent (methanol) to the catalyst (skeleton nickel) is 1: 2: 0.09; the temperature in the hydrogenation microreactor is controlled to be 130 ℃, and the pressure is controlled to be 0.3 MPa.
The structure of the hydrogenation microreactor is the same as that of example 1.
The yield of the phenylenediamine product after reaction is 99.8 percent calculated by m-dinitrobenzene, p-dinitrobenzene and o-dinitrobenzene.
Example 4
This example is the same as example 1 except for the hydrogenation microreactor.
As shown in fig. 5, the hydrogenation microreactor comprises a casing reactor main body, wherein the casing reactor main body comprises an inner casing 1, an intermediate casing 2 and an outer casing 3, the inner casing 1 is provided with internal threads and external threads, the intermediate casing 2 is provided with micropores penetrating through the wall of the casing, a spiral circulation path formed between the outer wall of the inner casing 1 and the inner wall of the intermediate casing 2 serves as a reaction channel 5, the inner casing serves as a heat exchange medium channel 6, and a circulation path formed between the outer wall of the intermediate casing and the inner wall of the outer casing serves as a gas channel 4. When the spiral circulation path formed between the outer wall of the middle sleeve and the inner wall of the outer sleeve is used as a gas channel, the reaction liquid moves outwards under the action of centrifugal force, and after the gas enters the reaction channel, the gas and the reaction liquid are continuously and repeatedly collided and mixed, so that the mass transfer effect is good.
The difference between the inner diameter of the middle sleeve and the maximum radius of the external thread of the inner sleeve is 1-3000 μm, preferably 500-1000 μm; the inner diameter of the intermediate sleeve is 1000-5000 μm (measured by the thread bulge).
The diameter of the micropores on the middle sleeve is 0.1-50 μm, in this embodiment, the diameter of the micropores on the middle sleeve is 10 μm, and the micropores are uniformly distributed on the inner sleeve.
The yield of the phenylenediamine product after the reaction is 99.8 percent based on the m-dinitrobenzene.
Example 5
This example is the same as example 2, except for the hydrogenation microreactor which is the same as example 4.
The yield of the phenylenediamine product after reaction is 99.9 percent based on the m-dinitrobenzene and the o-dinitrobenzene.
Example 6
A process for preparing phenylenediamine by a microreaction technique comprising the steps of: firstly, preparing nitro aromatic hydrocarbon to be reduced, a solvent and a catalyst into a suspension, continuously feeding the suspension into a hydrogenation microreactor after metering, and simultaneously continuously feeding hydrogen into the hydrogenation microreactor to perform continuous hydrogenation reduction reaction.
And (3) allowing the reaction liquid obtained in the hydrogenation microreactor to enter a hydrogenation ageing device for ageing, and detecting that the reaction liquid is at an end point when no nitro compound exists.
The molar ratio of hydrogen to m-dinitrobenzene added into the hydrogenation microreactor is 8: 1; the weight ratio of the m-dinitrobenzene to the solvent (methanol) to the catalyst (skeleton nickel) is 1: 3: 0.07; the temperature in the hydrogenation micro-reactor is controlled at 100 ℃, and the pressure is controlled at 1 MPa.
The structure of the hydrogenation microreactor is the same as that of example 1.
The nitryl arene to be reduced is prepared by the following steps:
1) primary nitrification: benzene and mixed acid continuously enter a first-stage nitration microreactor to carry out nitration reaction, and the obtained reaction liquid is aged and separated to obtain an organic phase containing nitrobenzene and a water phase containing sulfuric acid;
2) secondary nitrification: continuously feeding the organic phase containing nitrobenzene and the mixed acid obtained in the step 1) into a secondary nitration microreactor for nitration reaction, and aging and separating the obtained reaction liquid to obtain an organic phase containing mixed dinitrobenzene and a water phase containing sulfuric acid;
3) washing the organic phase containing the mixed dinitrobenzene obtained in the step 2) to obtain the nitroarene to be reduced.
The mixed acid is a mixture of nitric acid and sulfuric acid, and the molar ratio of the nitric acid to the benzene added in the step 1) is 0.99: 1; the molar ratio of the nitric acid added in the step 2) to the benzene added in the step 1) is 0.95: 1.
In the first-stage nitration microreactor, the reaction temperature is 30-75 ℃, and the residence time of reactants is 5-30 s.
In the secondary nitration microreactor, the reaction temperature is 70-90 ℃, and the residence time of reactants is 5-30 s.
The mixed acid added into the first-stage nitration microreactor comprises the following components in percentage by mass: 55-65% of sulfuric acid, 20-30% of nitric acid and 10-20% of water.
The mixed acid added into the secondary nitration microreactor comprises the following components in percentage by mass: 70-85% of sulfuric acid, 10-25% of nitric acid and 5-10% of water.
The washing comprises water washing and alkali washing, and the mass concentration of alkali liquor in the alkali washing is 5%.
The one-level nitration microreactor and the second-level nitration microreactor comprise a casing pipe reactor main body, the casing pipe reactor main body comprises an inner casing pipe, an intermediate casing pipe and an outer casing pipe, the inner casing pipe and the intermediate casing pipe are respectively provided with an internal thread and an external thread, the outer casing pipe is provided with an internal thread, a spiral circulation path formed between the outer wall of the inner casing pipe and the inner wall of the intermediate casing pipe is taken as a reaction channel, the spiral circulation path of the inner casing pipe is taken as a heat exchange medium channel I, and a spiral circulation path formed between the outer wall of the intermediate casing pipe and the inner wall of the outer casing pipe is taken as a heat exchange medium channel II. The external thread of the inner sleeve and the internal thread of the middle sleeve are opposite in direction, and when viewed from one end of the microreactor, one thread rotates clockwise, and the other thread rotates anticlockwise. The thread pitch of the external thread of the inner sleeve is equal to that of the internal thread of the middle sleeve. The external thread of the middle sleeve and the internal thread of the outer sleeve are opposite in direction, and when viewed from one end of the microreactor, one thread rotates clockwise, and the other thread rotates anticlockwise.
The difference between the maximum radius of the external thread of the inner sleeve and the minimum radius of the internal thread of the middle sleeve is 1-3000 μm; the difference between the maximum radius of the external thread of the middle sleeve and the minimum radius of the internal thread of the outer sleeve is 1000-3000 μm.
The flow directions of the fluids in the reaction channel and the heat exchange medium channel I are opposite, the flow directions of the fluids in the reaction channel and the heat exchange medium channel II are opposite, and the fluids in the reaction channel and the fluids in the inner heat exchange medium channel and the outer heat exchange medium channel are in a counter-current state.
The internal thread and the external thread are trapezoidal threads; the height of the trapezoidal thread is 1.5-10.5 mm, and the pitch of the trapezoidal thread is 2-20 mm.
Through detection, in the nitroaromatic to be reduced prepared by the embodiment, the m-dinitrobenzene accounts for 83%, the o-dinitrobenzene accounts for 10%, the p-dinitrobenzene accounts for 2%, and the nitrobenzene accounts for 5%.
The yield of the phenylenediamine product after the reaction is 99.8 percent based on m-dinitrobenzene, p-dinitrobenzene and o-dinitrobenzene.
Specific embodiments of the present application have been described above. It is to be understood that the present application is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the present application.
Claims (12)
1. The process for preparing the phenylenediamine by the micro-reaction technology is characterized by comprising the following steps of: metering the nitroaromatic hydrocarbon to be reduced, a solvent, a catalyst and hydrogen, and then continuously feeding the obtained product into a hydrogenation microreactor to perform hydrogenation reduction reaction;
the nitryl arene to be reduced is prepared by the following steps:
1) first-stage nitration: benzene and mixed acid continuously enter a primary nitrification micro-reactor to carry out nitrification reaction, and the obtained reaction liquid is aged and separated to obtain an organic phase containing nitrobenzene and a water phase containing sulfuric acid;
2) secondary nitrification: continuously feeding the organic phase containing nitrobenzene and the mixed acid obtained in the step 1) into a secondary nitration microreactor for nitration reaction, and aging and separating the obtained reaction liquid to obtain an organic phase containing mixed dinitrobenzene and a water phase containing sulfuric acid;
3) washing the organic phase containing the mixed dinitrobenzene obtained in the step 2) to obtain the nitroaromatic to be reduced;
the hydrogenation microreactor comprises a casing reactor main body, the casing reactor main body comprises an inner casing, an intermediate casing and an outer casing, the intermediate casing is provided with an internal thread and an external thread, the inner casing is provided with micropores penetrating through the pipe wall, a spiral circulation path formed between the outer wall of the inner casing and the inner wall of the intermediate casing serves as a reaction channel, the inner casing serves as a gas channel, and a spiral circulation path formed between the outer wall of the intermediate casing and the inner wall of the outer casing serves as a heat exchange medium channel.
2. The process for preparing phenylenediamine according to claim 1, wherein said reaction solution obtained in said microreactor is aged in a hydrogenation-aging device, and the end point is detected when no nitro compound is present.
3. The process for preparing phenylenediamine according to claim 1, wherein the molar ratio of hydrogen to nitroaromatic hydrocarbon added to the hydrogenation microreactor is 6-16: 1.
4. The process for preparing phenylenediamine according to claim 1, wherein the molar ratio of hydrogen to nitroaromatic hydrocarbon added to the hydrogenation microreactor is 8-12: 1.
5. the process for preparing phenylenediamine according to claim 1, wherein the weight ratio of the nitroaromatic to be reduced, the solvent and the catalyst in the hydrogenation microreactor is 1: 1.5-4: 0.05-0.1.
6. The process for preparing phenylenediamine according to claim 1, wherein the temperature in the microreactor for hydrogenation is controlled to be 50-160 ℃ and the pressure is controlled to be 0.3-10 MPa.
7. The process for preparing phenylenediamine according to claim 1, wherein the temperature in the hydrogenation microreactor is controlled to be 80-100 ℃ and the pressure in the hydrogenation microreactor is controlled to be 1-2.5 MPa.
8. A process for preparing phenylenediamine by a microreaction technique according to claim 1, wherein said catalyst is a nickel catalyst, a palladium catalyst or a platinum catalyst.
9. The process for preparing phenylenediamine by a microreaction technique according to claim 1, wherein said outer sleeve has an internal thread, said external thread of said intermediate sleeve and said internal thread of said outer sleeve are in opposite directions, and one of said threads is rotated clockwise and the other of said threads is rotated counterclockwise as viewed from one end of said microreactor.
10. The process for preparing phenylenediamine through a microreaction technique according to claim 1, wherein the hydrogenation microreactor comprises a casing-pipe reactor body, the casing-pipe reactor body comprises an inner casing pipe, an intermediate casing pipe and an outer casing pipe, the inner casing pipe is provided with internal threads and external threads, the intermediate casing pipe is provided with micropores penetrating through the pipe wall, a spiral circulation path formed between the outer wall of the inner casing pipe and the inner wall of the intermediate casing pipe is used as a reaction channel, the inner casing pipe is used as a heat exchange medium channel, and a circulation path formed between the outer wall of the intermediate casing pipe and the inner wall of the outer casing pipe is used as a gas channel.
11. The process for preparing phenylenediamine by a microreaction technique as claimed in claim 1, wherein said suspension is prepared by mixing a catalyst with a nitroaromatic to be reduced and a solvent, metering said suspension, and continuously feeding said suspension into said hydrogenation microreactor while continuously feeding hydrogen into said hydrogenation microreactor.
12. The process for preparing phenylenediamine by a microreaction technique according to claim 1, wherein the mixed acid is a mixture of nitric acid and sulfuric acid, and the molar ratio of the nitric acid to the benzene added in step 1) is 0.9-0.99: 1; the molar ratio of the nitric acid added in the step 2) to the benzene added in the step 1) is 0.9-0.99: 1.
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