CN114957013A - Production method of mixed dinitrobenzene - Google Patents
Production method of mixed dinitrobenzene Download PDFInfo
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- CN114957013A CN114957013A CN202210743311.1A CN202210743311A CN114957013A CN 114957013 A CN114957013 A CN 114957013A CN 202210743311 A CN202210743311 A CN 202210743311A CN 114957013 A CN114957013 A CN 114957013A
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- WDCYWAQPCXBPJA-UHFFFAOYSA-N 1,3-dinitrobenzene Chemical compound [O-][N+](=O)C1=CC=CC([N+]([O-])=O)=C1 WDCYWAQPCXBPJA-UHFFFAOYSA-N 0.000 title claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 127
- LQNUZADURLCDLV-UHFFFAOYSA-N nitrobenzene Chemical compound [O-][N+](=O)C1=CC=CC=C1 LQNUZADURLCDLV-UHFFFAOYSA-N 0.000 claims abstract description 97
- 239000002253 acid Substances 0.000 claims abstract description 96
- 238000005406 washing Methods 0.000 claims abstract description 89
- 238000006396 nitration reaction Methods 0.000 claims abstract description 65
- 238000006243 chemical reaction Methods 0.000 claims abstract description 57
- 239000012074 organic phase Substances 0.000 claims abstract description 57
- 238000000926 separation method Methods 0.000 claims abstract description 47
- 238000000034 method Methods 0.000 claims abstract description 30
- 238000002156 mixing Methods 0.000 claims abstract description 26
- 239000000203 mixture Substances 0.000 claims abstract description 22
- 239000002608 ionic liquid Substances 0.000 claims abstract description 18
- 238000010790 dilution Methods 0.000 claims abstract description 10
- 239000012895 dilution Substances 0.000 claims abstract description 10
- 238000005119 centrifugation Methods 0.000 claims abstract description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 94
- 239000012071 phase Substances 0.000 claims description 50
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 42
- 229910017604 nitric acid Inorganic materials 0.000 claims description 42
- 239000000243 solution Substances 0.000 claims description 36
- 239000003513 alkali Substances 0.000 claims description 35
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 32
- 239000000463 material Substances 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 7
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 7
- 235000017550 sodium carbonate Nutrition 0.000 claims description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical group [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 3
- 125000000217 alkyl group Chemical group 0.000 claims description 3
- 150000001450 anions Chemical class 0.000 claims description 3
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 3
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 3
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 3
- -1 bisulfate ion Chemical class 0.000 claims description 2
- 239000003054 catalyst Substances 0.000 abstract description 10
- 238000007865 diluting Methods 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 2
- 239000000872 buffer Substances 0.000 description 23
- 239000005416 organic matter Substances 0.000 description 21
- 238000010438 heat treatment Methods 0.000 description 20
- 239000011259 mixed solution Substances 0.000 description 18
- 239000007788 liquid Substances 0.000 description 13
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 12
- 239000003599 detergent Substances 0.000 description 8
- 239000003085 diluting agent Substances 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 239000012043 crude product Substances 0.000 description 6
- 239000003153 chemical reaction reagent Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- 230000007547 defect Effects 0.000 description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- CVCFHGVTPLNQRD-UHFFFAOYSA-N 1,3-dimethyl-1,2-dihydroimidazol-1-ium;chloride Chemical compound [Cl-].CN1C[NH+](C)C=C1 CVCFHGVTPLNQRD-UHFFFAOYSA-N 0.000 description 2
- SWWCIHVYFYTXDK-UHFFFAOYSA-N 1,3-dimethyl-2h-imidazole Chemical class CN1CN(C)C=C1 SWWCIHVYFYTXDK-UHFFFAOYSA-N 0.000 description 2
- VNEAMDQMRRQFMU-UHFFFAOYSA-N 1,3-dimethyl-2h-imidazole;sulfuric acid Chemical compound OS(O)(=O)=O.CN1CN(C)C=C1 VNEAMDQMRRQFMU-UHFFFAOYSA-N 0.000 description 2
- MKFKRDBGTIMGAC-UHFFFAOYSA-N [N+](=O)(O)[O-].CN1CN(C=C1)C Chemical compound [N+](=O)(O)[O-].CN1CN(C=C1)C MKFKRDBGTIMGAC-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- GEYOCULIXLDCMW-UHFFFAOYSA-N 1,2-phenylenediamine Chemical compound NC1=CC=CC=C1N GEYOCULIXLDCMW-UHFFFAOYSA-N 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 150000004982 aromatic amines Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-M hydrogensulfate Chemical compound OS([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- LQNUZADURLCDLV-IDEBNGHGSA-N nitrobenzene Chemical group [O-][N+](=O)[13C]1=[13CH][13CH]=[13CH][13CH]=[13CH]1 LQNUZADURLCDLV-IDEBNGHGSA-N 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- 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
-
- 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
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
-
- 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
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The application belongs to the field of production of mixed dinitrobenzene, and particularly relates to a production method of mixed dinitrobenzene. The method comprises the following steps: mixing a mixture of nitrobenzene and a catalyst (1-alkyl-3-methylimidazolium salt ionic liquid) with acid, feeding the mixture into a microreactor for nitration, diluting the mixture obtained by nitration with water, performing centrifugal separation, centrifuging and washing an organic phase obtained by centrifugation, and finally separating to obtain a washed organic phase. The method provided by the application carries out nitration and dilution through the microreactor, and adopts a centrifuge to wash and separate to continuously produce the mixed dinitrobenzene. When the microreactor is used for nitration, the mass transfer and heat transfer effects in the reaction process are good, and the separation efficiency of centrifugal equipment is high. The method has the advantages of intrinsic safety, high product selectivity, high production efficiency and the like, and has wide market prospect.
Description
Technical Field
The invention belongs to the field of production of mixed dinitrobenzene, and particularly relates to a production method of mixed dinitrobenzene.
Background
The mixed dinitrobenzene is an important chemical intermediate, is used for producing dyes, paints and coatings, and is also used for producing phenylenediamine.
At present, most domestic enterprises adopt a kettle type reactor to produce mixed dinitrobenzene, such as CN102311347A discloses the preparation of mixed dinitrobenzene by kettle reaction, but because of the large volume of the kettle type reaction kettle (generally, the volume of a single kettle is more than or equal to 5 m) 3 ) The material stock is more, and once an accident occurs, the danger is very high. Meanwhile, in the subsequent separation, because the tower is adopted for separation, the tower has large volume and large storage amount, and great potential safety hazard exists. Therefore, it is very important to find an industrial production method of mixed dinitrobenzene with wide raw material source, intrinsic safety, good selectivity and high efficiency.
The micro-reaction technology originates from Europe in the early 90 s of the 20 th century, the size of a reactor channel is micron-sized, and compared with the traditional reactor, the micro-reactor has the advantages of short molecular diffusion distance, fast mass transfer, laminar flow in the channel, narrow residence time distribution, no back mixing, overlarge specific surface area of unit volume, fast heat transfer speed, strong heat exchange capacity and easy temperature control. Microreactors include microchannel reactors, tubular reactors, and other similar reactors.
Because the micro-reactor has small volume, the liquid storage capacity is small, the micro-reactor is particularly suitable for dangerous reactions such as nitration and the like, and even if danger occurs, the held small liquid can not cause more serious consequences.
Patent CN102432410A discloses a method for obtaining mixed dinitrobenzene by using a tubular reactor, then directly separating out organic matters, and then respectively carrying out static washing and separation. The technical scheme has the defects that the conversion rate of the raw material nitride is insufficient, and nitric acid is required to be added separately to promote the conversion of the incompletely reacted nitrobenzene. Meanwhile, washing and separation are carried out in different static devices, and the problems of long flow, low separation efficiency and the like exist.
Patent CN109232272A discloses a safe and environment-friendly aromatic amine production system and process, wherein a microchannel reactor is adopted in the nitration process, then a tubular separator is directly adopted to separate organic matters and acid, and then nitrated compounds are washed and separated by a tower.
Patent CN112979472A discloses a method for continuously producing dinitrobenzene, wherein a microchannel reactor is adopted for nitration reaction, organic matters and acid in the dinitrobenzene are required to be separated after each stage of nitration in the process, and concentrated nitric acid is required to be supplemented in the nitration process, so that the problems of complex flow, complex operation and the like exist.
Patent CN113967454A discloses a device for high-selectivity continuous synthesis of mixed dinitrobenzene, wherein nitration is carried out by adopting a microchannel reactor, the defects are that the existence of a time delay mixer can increase the retention time of reaction mixed materials, and the subsequent washing and separation of nitrated compounds are carried out step by step, so that more equipment is used, and the washing and separation efficiency is influenced.
In the above application, after the micro-reaction nitration, the direct separation of the acid and the organic matter may cause more organic matter dissolved in the acid, which seriously affects the separation efficiency.
In addition, because m-dinitrobenzene is the main product of dinitration, the improvement of the ratio of the intermediate dinitrobenzene in the traditional dinitration product is an important technical problem which needs to be continuously solved.
Disclosure of Invention
In view of the above, the invention aims to provide a method for producing mixed dinitrobenzene, and the method adopted by the scheme of the invention has the advantages of intrinsically safe process, high product selectivity, high production efficiency and the like.
The invention provides a production method of mixed dinitrobenzene, which comprises the following steps:
mixing a mixture of nitrobenzene and 1-alkyl-3-methylimidazolium salt ionic liquid with acid liquor, and feeding the mixture into a main feed inlet of a microreactor for partial nitration reaction; then mixing the mixture with acid liquor added into the microreactor through the first feed inlet to perform complete nitration reaction; then mixing with water added into the microreactor through a second feed inlet for dilution; then discharging the microreactor from a discharge hole;
the product of the microreactor discharged from the discharge port enters a first centrifuge for centrifugal separation, and the obtained organic phase is subjected to centrifugal washing sequentially through a second centrifuge, a third centrifuge and a fourth centrifuge to obtain mixed dinitrobenzene;
the centrifugal washing step specifically comprises the following steps: sending the organic phase obtained by centrifugation in the first centrifuge into a first feed port of a second centrifuge, mixing the organic phase with water added through a second feed port of the second centrifuge, and then carrying out centrifugal prewashing; feeding the organic phase obtained by centrifugal prewashing into a first feed inlet of a third centrifuge, mixing the organic phase with alkali liquor added through a second feed inlet of the third centrifuge, and then carrying out centrifugal alkali washing; sending the organic phase obtained by the centrifugal alkali washing into a first feed port of a fourth centrifuge, mixing the organic phase with water added through a second feed port of the fourth centrifuge, and then carrying out centrifugal final washing, wherein the obtained organic phase is discharged out of the centrifuge from an organic phase discharge port of the fourth centrifuge; and in the centrifugal washing process, the water phase is discharged out of the centrifuge from a water phase discharge port of the centrifuge.
Preferably, the microreactor is a microchannel reactor or a tubular reactor.
Preferably, the amount ratio of the nitrobenzene to the nitric acid in the acid solution for reaction (partial nitration reaction and complete nitration reaction) is 1: (1.05-1.1).
Preferably, the alkyl group in the 1-alkyl-3-methylimidazolium salt is methyl, ethyl, propyl or butyl, and the anion in the salt is chloride ion, nitrate ion or bisulfate ion; the dosage of the 1-alkyl-3-methylimidazolium salt is 0.4-9 wt% of the mass of nitric acid in the acid solution for reaction.
Preferably, adding the acid solution for the partial nitration reaction and the complete nitration reaction into the microreactor for 2-3 times; when the acid liquor is added for 2 times, the adding proportion is (53-70) wt% according to the total adding amount of the acid liquor: (47-30) wt%, the total addition amount being 100 wt%; when the materials are added for 3 times, the adding proportion is (43-51) wt%: (31-42) wt%: (7-26) wt%, the total amount added being 100 wt%.
Preferably, the acid solution used for the partial nitration reaction and the complete nitration reaction is a mixed acid solution containing nitric acid and sulfuric acid, wherein the mass content of the nitric acid is 14-24%, and the mass content of the sulfuric acid is 69-83%.
Preferably, the temperature of the partial nitrification reaction and the temperature of the complete nitrification reaction are independently selected to be 76-85 ℃, and the pressure of the partial nitrification reaction and the pressure of the complete nitrification reaction are independently selected to be 0.8-1.3 MPa.
Preferably, after the dilution, the mass percentage concentration of the sulfuric acid in the system is 65-75%.
Preferably, the alkali liquor is 5-15 wt% of soda solution.
Preferably, in the centrifugal prewashing process, the mass ratio of the organic phase to the water is 1: (0.12-0.28); in the centrifugal alkali washing process, the mass ratio of the organic phase to the alkali liquor is 1: (0.11-0.26); in the centrifugal final washing process, the mass ratio of the organic phase to the water is 1: (0.11-0.28).
Compared with the prior art, the invention provides a production method of mixed dinitrobenzene, which comprises the following steps: mixing a mixture of nitrobenzene and a catalyst (1-alkyl-3-methylimidazolium salt ionic liquid) with acid, feeding the mixture into a microreactor for nitration reaction, diluting the mixture obtained by nitration reaction with water, performing centrifugal separation, performing centrifugal washing on an organic phase obtained by centrifugation, and finally separating to obtain a washed organic phase. The invention provides a process method for continuously producing mixed dinitrobenzene by nitration and dilution through a microreactor and washing and separation through a centrifugal machine. When the microreactor is used for nitration, the mass transfer and heat transfer effects in the reaction process are good, and the separation efficiency of centrifugal equipment is high. The method has the advantages of intrinsic safety, high product selectivity, high production efficiency and the like, and has wide market prospect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a flow diagram of a process for producing mixed dinitrobenzene according to an embodiment of the present invention.
The drawings are numbered as follows: t1 is a nitrobenzene and catalyst mixing buffer device, T2 is an acid liquor buffer device, T3 is an acid diluent buffer device, T4 is a prewashing liquid buffer device, T5 is an alkali liquor buffer device, T6 is an alkali liquor buffer device, C1 is a first centrifuge, C2 is a second centrifuge, C3 is a third centrifuge, C4 is a fourth centrifuge, 1 is a first feed inlet of the nitrobenzene and catalyst mixing buffer device, 2 is a second feed inlet of the nitrobenzene and catalyst mixing buffer device, 3 is a first feed inlet of the acid liquor buffer device, 4 is a second feed inlet of the acid liquor buffer device, 5 is a feed inlet of the acid diluent buffer device, 6 is a main feed inlet of the microreactor, 7 is a first branch feed inlet of the microreactor, 8 is a second branch feed inlet of the microreactor, 9 is a feed inlet of the first centrifuge, 10 is a first feed inlet of the second centrifuge, and 11 is a water phase discharge outlet of the first centrifuge, 12 is a second feed inlet of the second centrifuge, 13 is a first feed inlet of the third centrifuge, 14 is a water phase discharge outlet of the second centrifuge, 15 is a first feed inlet of the alkali liquor caching device, 16 is a second feed inlet of the alkali liquor caching device, 17 is a second feed inlet of the third centrifuge, 18 is a first feed inlet of the fourth centrifuge, 19 is a water phase discharge outlet of the third centrifuge, 20 is a second feed inlet of the fourth centrifuge, 21 is an organic phase discharge outlet of the fourth centrifuge, 22 is a water phase discharge outlet of the fourth centrifuge, 23 is a heat medium feed inlet of a microreactor heating section jacket layer, and 24 is a heat medium discharge outlet of the microreactor heating section jacket layer.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for producing mixed dinitrobenzene, which comprises the following steps of carrying out nitration reaction in a microreactor, diluting a mixture obtained by the nitration reaction with water, carrying out centrifugal separation to obtain crude mixed dinitrobenzene, and carrying out centrifugal washing on the crude mixed dinitrobenzene, so that the conversion rate, the reaction efficiency and the product purity are effectively improved, and the specific process is as follows:
1) preparing a nitrobenzene and catalyst mixture, adjusting acid and adjusting alkali:
under the condition of continuous stirring, adding the ionic liquid 1-alkyl-3-methylimidazolium salt and nitrobenzene into a nitrobenzene and catalyst mixing buffer device (T1) from a first feed inlet (1) and a second feed inlet (2) of the nitrobenzene and catalyst mixing buffer device respectively, so that the ionic liquid is uniformly dispersed in the nitrobenzene. Wherein the alkyl in the 1-alkyl-3-methylimidazolium salt is one of methyl, ethyl, propyl or butyl, and the anion in the salt is one of chloride ion, nitrate ion or hydrogen sulfate ion.
Under stirring, sulfuric acid and nitric acid are added into an acid liquor caching device (T2) from a first feeding hole (3) and a second feeding hole (4) of the acid liquor caching device according to a certain proportion. Wherein the mass content of the nitric acid is preferably 14-24%; the mass content of the sulfuric acid is preferably 69-83%.
In the processes of preparing a nitrobenzene and catalyst mixture and adjusting acid, the amount of the salt in the 1-alkyl-3-methylimidazolium salt is preferably 0.5-8% of the mass of nitric acid for reaction. The mass ratio of the nitrobenzene to the nitric acid in the mixed acid is preferably 1 (1.05-1.1). The acid buffer device (T2) is provided with a jacket, and condensed water is introduced into the jacket to dissipate heat generated during mixing.
Under stirring, adding soda ash and water into the alkali liquor buffer device (T5) from the first feed inlet (15) and the second feed inlet (16) of the alkali liquor buffer device according to a certain proportion. Wherein, the alkali liquor is preferably 5-15% of soda solution. The alkali buffer device (T5) is provided with a jacket, and condensed water is introduced into the jacket to dissipate heat generated during mixing.
2) Nitration reaction:
mixing an ionic liquid mixture of nitrobenzene and 1-alkyl-3-methylimidazolium salt in a nitrobenzene and catalyst mixing buffer device (T1) with mixed acid in an acid liquor buffer device (T2), conveying the mixture to a main feed inlet (6) of a microreactor through a pump, mixing, and feeding the mixture into the microreactor for nitration reaction, wherein part of nitrobenzene and part of nitric acid are nitrated; and then, the mixed solution after the nitration reaction is continuously subjected to complete nitration with the mixed acid entering the micro-reactor through the first feed inlet (7) to obtain the mixed solution after the complete nitration reaction. The main components of the mixed solution are mixed dinitrobenzene, a small amount of unreacted nitric acid, sulfuric acid with a catalytic effect and 1-alkyl-3-methylimidazolium salt ionic liquid.
In the invention, in order to ensure the relative stability of the reaction temperature, the heating section jacket layer of the micro-reactor is preferably maintained at a certain temperature by hot water at a certain temperature entering from a heating medium inlet (23) of the micro-reactor, and the hot water flows out from a heating medium outlet (24).
In the invention, the mixed acid added into the main feed inlet (6) and the first branch feed inlet (7) can be added into the microreactor for 2-3 times; according to the total addition amount, when the materials are added for 2 times, the preferable adding proportion is (53-70) wt% to (47-30) wt%, and the total adding amount is 100 wt%; when the materials are added for 3 times, the preferable adding proportion is (43-51) wt%, (31-42) wt%, (7-26) wt%, and the total adding amount is 100 wt%.
In the present invention, the temperature during the nitration reaction is preferably controlled to 76 to 85 ℃ and the pressure during the nitration reaction is preferably controlled to 0.8 to 1.3 MPa.
3) Diluting:
in order to reduce the dissolution of nitrobenzene in sulfuric acid, water is continuously added into the microreactor after nitration reaction, and the sulfuric acid in the mixed solution is diluted. And conveying water in the acid diluent buffer device (T3) to a second feed inlet (8) of the microreactor through a pump, entering the microreactor, and mixing the water with the mixed solution after complete nitration in the microreactor to dilute the sulfuric acid.
In the invention, in order to ensure the relative stability of the separation temperature, the heating section jacket layer of the micro-reactor is preferably maintained at a certain temperature by hot water at a certain temperature entering from a heating medium inlet (23) of the micro-reactor, and the hot water flows out from a heating medium outlet (24).
In the present invention, the number of dilution is preferably 1 to 3. The concentration of the diluted sulfuric acid is preferably 65-75%.
4) Separation:
the diluted mixed solution enters a centrifuge (C1) through a first centrifuge feed inlet (9) for centrifugal separation, and the sulfuric acid of the separated heavy component is output through a first centrifuge aqueous phase discharge outlet (11); the obtained organic phase (crude product mixed with dinitrobenzene) is output through a discharge hole of the first centrifuge and then enters a second centrifuge (C2) through a feed hole (10) of the second centrifuge.
In the invention, the output liquid of the water phase discharge port (11) of the first centrifuge is preferably 65-75% sulfuric acid. After being concentrated by the acid concentration device, the sulfuric acid can be continuously recycled as concentrated acid.
In order to ensure the relative stability of the separation temperature, the outer jacket layer of the centrifuge is maintained at a certain temperature by using hot water to prevent the mixed dinitrobenzene from being solidified.
5) Washing:
and (3) continuously inputting the crude product mixed with dinitrobenzene obtained by the separation into a centrifugal machine, and carrying out centrifugal washing. The centrifugal washing sequence comprises pre-washing, alkali washing and final washing, and specifically comprises the following steps:
pre-washing: the crude mixed dinitrobenzene delivered to the first inlet (10) of the second centrifuge is mixed thoroughly at the lower end of the centrifuge (C2) with a metered amount of water delivered to the second inlet (12) of the second centrifuge by means of a pump and then centrifuged. The water phase obtained by separation is output from a water phase discharge port (14) of a second centrifuge; the obtained organic phase (the mixed dinitrobenzene after the pre-washing) is output and then enters a third centrifuge (C3) through a first feed inlet (13) of the third centrifuge. By this continuous prewashing, the crude dinitrobenzene can be washed free of most of the acid dissolved therein.
Alkali washing: the mixed dinitrobenzene which is conveyed to the first feeding hole (13) of the third centrifuge after being pre-washed and the excessive soda solution which is conveyed to the second feeding hole (17) of the third centrifuge through a pump are fully mixed at the lower end of the centrifuge (C3) and then are centrifugally separated. The water phase obtained by separation is output from a water phase discharge port (19) of a third centrifuge; the organic phase (alkali-washed mixed dinitrobenzene) is output and then enters a fourth centrifuge (C4) through a first feed inlet (18) of the fourth centrifuge. By this continuous alkaline washing, all the acid in the nitrobenzene can be washed away.
Final washing: the mixed dinitrobenzene after alkali washing conveyed to the first feeding hole (18) of the fourth centrifuge and water conveyed to the second feeding hole (20) of the fourth centrifuge through a pump are fully mixed at the lower end of the centrifuge (C4) and then are subjected to centrifugal separation. The water phase obtained by separation is output from a discharge port (22) of the organic phase of the fourth centrifuge; the obtained organic phase is output from a water phase discharge port (21) of a fourth centrifuge to obtain the mixed dinitrobenzene with higher purity. Through this continuous final washing, a small amount of alkali in nitrobenzene can be washed away.
In the invention, in order to ensure the relative stability of the temperature of the pre-washing, the alkali washing and the final washing, the outer jacket layer of the centrifuge maintains the temperature by using hot water with certain temperature so as to prevent the nitrobenzene from being solidified.
In the invention, in the pre-washing process, the mass ratio of the organic matter to the washing reagent water is preferably 1 (0.12-0.28); in the alkali washing process, the detergent is preferably a 5-15 wt% of soda solution, and the mass ratio of the organic matter to the detergent soda solution is preferably 1 (0.11-0.26); in the final washing process, the mass ratio of the organic matters to the washing reagent water is preferably 1 (0.11-0.28).
The production method provided by the invention utilizes the microreactor to carry out nitration reaction, and the centrifuge carries out separation, washing and purification. The method has the advantages of intrinsic safety, high product selectivity and high production efficiency; more specifically, the method has the following advantages:
1) the nitrobenzene conversion rate is high: mixed acid prepared from nitrobenzene, sulfuric acid and nitric acid and ionic liquid are adopted for reaction, and the conversion rate of the nitrobenzene is obviously higher than that of the nitrobenzene without the ionic liquid;
2) the reaction and separation process is safe, fast and efficient: in the reactor and diluter type, a micro-reactor is adopted, so that the problem of great safety caused by large liquid storage amount in the traditional kettle type reaction is solved, the reactor has the advantage of intrinsic safety, the residence time of materials in the micro-reactor is about 5-30 seconds, the defect that the residence time in the traditional kettle type reactor is more than 30 minutes is overcome, and the reactor has the characteristics of obvious reaction speed and high reaction efficiency;
3) the washing and purifying efficiency is high: when a centrifugal machine is used for pre-washing, alkaline washing and final washing, the defects of large liquid storage amount and high risk in the traditional tower type washing are overcome due to the fact that the liquid storage amount in the centrifugal machine is small, the retention time of materials in the centrifugal machine is about 2-8 seconds, and the tower type washing device has the advantages of being high in washing and purifying speed and high in efficiency.
For the sake of clarity, the following examples and comparative examples are described in detail below.
Example 1
The nitration reaction is carried out in a microchannel reactor, the process flow is shown in figure 1, and the specific process comprises the following steps:
the mixture of nitrobenzene and chlorinated 1-methyl-3-methylimidazole ionic liquid and mixed acid is conveyed to a main feed inlet (6) of a micro-reactor through a pump to be mixed and enters the micro-channel reactor for nitration reaction, and at the moment, partial benzene and partial nitric acid are nitrated; then, the mixed solution after the nitration reaction is continuously subjected to complete nitration with the mixed acid entering the micro-channel reactor through the first feed inlet (7) to obtain the mixed solution after the complete nitration reaction; the mixed liquid is mixed with water conveyed by an acid diluent buffer device (T3) at a second feed inlet (8) and enters a microchannel reactor to dilute sulfuric acid; the diluted mixed solution enters a centrifuge (C1) through a first centrifuge inlet (9) for centrifugal separation; the sulfuric acid of the heavy component obtained by separation is output through a water phase discharge port (11) of a first centrifugal machine; the obtained organic phase (crude product mixed nitrobenzene) enters a second centrifuge (C2) through a first feeding hole (10) of the second centrifuge, and is fully mixed with water with a metered amount which is conveyed to a second feeding hole (12) of the second centrifuge through a pump at the lower end of the centrifuge (C2) for centrifugal separation; the separated water phase is output from a water phase discharge port (14) of the second centrifuge, the obtained organic phase enters a third centrifuge (C3) through a first feed port (13) of the third centrifuge, and is fully mixed with the soda solution conveyed to a second feed port (17) of the third centrifuge through a pump at the lower end of the centrifuge (C3) for centrifugal separation; the separated water phase is output from a water phase discharge port (19) of the third centrifuge, the obtained organic phase enters a fourth centrifuge (C4) through a first feed port (18) of the fourth centrifuge, and is fully mixed with water conveyed to a second feed port (20) of the fourth centrifuge through a pump at the lower end of the centrifuge (C4) for centrifugal separation; the separated water phase is output from a fourth centrifuge organic phase discharge port (22), and the obtained organic phase is output from a fourth centrifuge water phase discharge port (21);
in the embodiment, the mass ratio of nitrobenzene to nitric acid in the mixed acid is 1: 1.05; the dosage of the chlorinated 1-methyl-3-methylimidazole ionic liquid is 0.5 percent of the mass of the nitric acid for reaction; the mass content of nitric acid and sulfuric acid in the mixed acid is 14% and 69%; adding the used mixed acid into a microchannel reactor for 2 times, wherein the ratio of adding the mixed acid for 2 times is 53 wt% to 47 wt% according to the total amount of the added mixed acid; water at a second feed inlet (8) enters the microchannel reactor for 3 times, and the water consumption ratio of 3 times is 2:3: 5; the mass percentage concentration of the diluted sulfuric acid is 65 percent; the temperature of the nitration reaction is controlled at 76 ℃, and the pressure is controlled at 0.8 MPa;
in the embodiment, in order to keep the reaction temperature relatively stable, the heating section jacket layer of the microreactor is preferably maintained at a certain temperature by hot water at a certain temperature entering from a heating medium inlet (23) of the microreactor, and the hot water flows out from a heating medium outlet (24);
in the embodiment, the concentration of sulfuric acid output by a water phase discharge port (11) of the first centrifuge is 65%, and the sulfuric acid is concentrated by an acid concentration device and then continuously recycled as concentrated acid;
in this example, in the second centrifuge (C2), the mass ratio of organic matter to water at the second feed inlet (12) of the second centrifuge is 1: 0.12; in the third centrifuge (C3), the concentration of the soda solution at the second feeding hole (17) is 5 wt%; the mass ratio of the organic matter to the soda ash solution is 1: 0.11; in the fourth centrifuge (C4), the mass ratio of the organic matters to the water at the second feed inlet (20) of the fourth centrifuge is 1: 0.11;
in this embodiment, in order to ensure the temperature is relatively stable during centrifugation, the outer jacket layer of the centrifuge is maintained at a certain temperature by using hot water to prevent the mixed dinitrobenzene from solidifying.
Example 2
The nitration reaction is carried out in a microchannel reactor, the process flow is shown in figure 1, and the specific process comprises the following steps:
the nitrobenzene and 1-methyl-3-methylimidazole nitrate ionic liquid mixture and mixed acid are conveyed to a main feed inlet (6) of the microreactor through a pump to be mixed and enter the microchannel reactor for nitration reaction, and at the moment, partial benzene and partial nitric acid are nitrated; then, the mixed solution after the nitration reaction is continuously subjected to complete nitration with the mixed acid entering the micro-channel reactor through the first feed inlet (7) to obtain the mixed solution after the complete nitration reaction; the mixed liquid is mixed with water conveyed by an acid diluent buffer device (T3) at a second feed inlet (8) and enters a microchannel reactor to dilute sulfuric acid; the diluted mixed solution enters a centrifuge (C1) through a first centrifuge feed inlet (9) for centrifugal separation; the sulfuric acid of the heavy component obtained by separation is output through a water phase discharge port (11) of a first centrifugal machine; the obtained organic phase (crude product mixed nitrobenzene) enters a second centrifuge (C2) through a first feeding hole (10) of the second centrifuge, and is fully mixed with water with a metered amount which is conveyed to a second feeding hole (12) of the second centrifuge through a pump at the lower end of the centrifuge (C2) for centrifugal separation; the separated water phase is output from a water phase discharge port (14) of the second centrifuge, the obtained organic phase enters a third centrifuge (C3) through a first feed port (13) of the third centrifuge, and is fully mixed with the soda solution conveyed to a second feed port (17) of the third centrifuge through a pump at the lower end of the centrifuge (C3) for centrifugal separation; the separated water phase is output from a water phase discharge port (19) of the third centrifuge, the obtained organic phase enters a fourth centrifuge (C4) through a first feed port (18) of the fourth centrifuge, and is fully mixed with water conveyed to a second feed port (20) of the fourth centrifuge through a pump at the lower end of the centrifuge (C4) for centrifugal separation; the separated water phase is output from a fourth centrifuge organic phase discharge port (22), and the obtained organic phase is output from a fourth centrifuge water phase discharge port (21);
in the embodiment, the mass ratio of the nitrobenzene to the nitric acid in the mixed acid is 1: 1.08; in the 1-methyl-3-methylimidazole nitrate ionic liquid, the amount of the salt is 4 percent of the mass of the nitric acid for reaction; the mass content of nitric acid and the mass content of sulfuric acid in the mixed acid are respectively 19% and 77%; the used mixed acid is added into the microchannel reactor for 2 times, and the proportion of adding the mixed acid for 2 times is 60 wt% to 40 wt% according to the total addition; the water of the second feed inlet (8) enters the microchannel reactor for 2 times, and the water consumption ratio of 2:3 is obtained after 2 times; the mass percentage concentration of the diluted sulfuric acid is 70 percent; the temperature of the nitration reaction is controlled at 85 ℃, and the pressure is controlled at 1.3 MPa;
in the embodiment, in order to keep the reaction temperature relatively stable, the heating section jacket layer of the microreactor is preferably maintained at a certain temperature by hot water at a certain temperature entering from a heating medium inlet (23) of the microreactor, and the hot water flows out from a heating medium outlet (24);
in the embodiment, the concentration of sulfuric acid output from a water phase discharge port (11) of the first centrifuge is 70%, and the sulfuric acid is concentrated by an acid concentration device and then continuously recycled as concentrated acid;
in this example, in the second centrifuge (C2), the mass ratio of organic matter to water at the second feed inlet (12) of the second centrifuge is 1: 0.2; in the third centrifuge (C3), the concentration of the sodium carbonate solution at the second feed inlet (17) is 10 wt%; the mass ratio of the organic matter to the soda solution is 1: 0.19; in the fourth centrifuge (C4), the mass ratio of the organic matters to the water at the second feed inlet (20) of the fourth centrifuge is 1: 0.2;
in this embodiment, in order to ensure the temperature is relatively stable during centrifugation, the outer jacket layer of the centrifuge is maintained at a certain temperature by using hot water to prevent the mixed dinitrobenzene from solidifying.
Example 3
The nitration reaction is carried out in a microchannel reactor, the process flow is shown in figure 1, and the specific process comprises the following steps:
the mixture of nitrobenzene and 1-methyl-3-methylimidazole bisulfate ionic liquid and mixed acid are conveyed to a main feed inlet (6) of a micro-reactor through a pump to be mixed and enter the micro-channel reactor for nitration reaction, and at the moment, part of benzene and part of nitric acid are nitrated; then, the mixed solution after the nitration reaction is continuously subjected to complete nitration with the mixed acid entering the micro-channel reactor through the first feed inlet (7) to obtain the mixed solution after the complete nitration reaction; the mixed liquid is mixed with water conveyed by an acid diluent buffer device (T3) at a second feed inlet (8) and enters a microchannel reactor to dilute sulfuric acid; the diluted mixed solution enters a centrifuge (C1) through a first centrifuge feed inlet (9) for centrifugal separation; the sulfuric acid of the heavy component obtained by separation is output through a water phase discharge port (11) of a first centrifugal machine; the obtained organic phase (crude product mixed nitrobenzene) enters a second centrifuge (C2) through a first feeding hole (10) of the second centrifuge, and is fully mixed with water with a metered amount which is conveyed to a second feeding hole (12) of the second centrifuge through a pump at the lower end of the centrifuge (C2) for centrifugal separation; the separated water phase is output from a water phase discharge port (14) of the second centrifuge, the obtained organic phase enters a third centrifuge (C3) through a first feed port (13) of the third centrifuge, and is fully mixed with the soda solution conveyed to a second feed port (17) of the third centrifuge through a pump at the lower end of the centrifuge (C3) for centrifugal separation; the separated water phase is output from a water phase discharge port (19) of the third centrifuge, the obtained organic phase enters a fourth centrifuge (C4) through a first feed port (18) of the fourth centrifuge, and is fully mixed with water conveyed to a second feed port (20) of the fourth centrifuge through a pump at the lower end of the centrifuge (C4) for centrifugal separation; the separated water phase is output from a fourth centrifuge organic phase discharge port (22), and the obtained organic phase is output from a fourth centrifuge water phase discharge port (21);
in this example, the mass ratio of nitrobenzene used to nitric acid in the mixed acid was 1: 1.1; in the 1-methyl-3-methylimidazole bisulfate ionic liquid, the amount of salt is 8 percent of the mass of nitric acid for reaction; the mass content of nitric acid and sulfuric acid in the mixed acid is 24% and 69%; adding the used mixed acid into a microchannel reactor for 2 times, wherein the ratio of adding the mixed acid for 2 times is 70 wt% to 30 wt% according to the total amount of the added mixed acid; water at a second feed inlet (8) enters the microchannel reactor at one time, and the mass percentage concentration of the diluted sulfuric acid is 75%; the temperature of the nitration reaction is controlled at 80 ℃, and the pressure is controlled at 1.0 MPa;
in the embodiment, in order to keep the reaction temperature relatively stable, the heating section jacket layer of the microreactor is preferably maintained at a certain temperature by hot water at a certain temperature entering from a heating medium inlet (23) of the microreactor, and the hot water flows out from a heating medium outlet (24);
in the embodiment, the concentration of the sulfuric acid output from the water phase discharge port (11) of the first centrifuge is 75%, and the sulfuric acid is concentrated by the acid concentration device and then continuously recycled as concentrated acid.
In this example, in the second centrifuge (C2), the mass ratio of organic matter to water at the second feed inlet (12) of the second centrifuge is 1: 0.28; in the third centrifuge (C3), the concentration of the soda solution at the second feeding hole (17) is 15 wt%; the mass ratio of the organic matter to the soda solution is 1: 0.26; in the fourth centrifuge (C4), the mass ratio of the organic matters to the water at the feed inlet (20) of the second centrifuge is 1: 0.28;
in this embodiment, in order to ensure the temperature is relatively stable during centrifugation, the outer jacket layer of the centrifuge is maintained at a certain temperature by using hot water to prevent the mixed dinitrobenzene from solidifying.
Example 4
The nitration reaction is carried out in a microchannel reactor, the process flow is shown in figure 1, and the specific process comprises the following steps:
the mixture of nitrobenzene and 1-methyl-3-methylimidazole chloride ionic liquid and mixed acid are conveyed to a main feed inlet (6) of a micro-reactor through a pump to be mixed and enter the micro-channel reactor for nitration reaction, and at the moment, part of benzene and part of nitric acid are nitrated; then, the mixed solution after the nitration reaction is continuously subjected to complete nitration with the mixed acid entering the micro-channel reactor through the first feed inlet (7) to obtain the mixed solution after the complete nitration reaction; the mixed liquor is mixed with water conveyed by an acid diluent buffer device (T3) at a second feed inlet (8) and enters a microchannel reactor to dilute sulfuric acid; the diluted mixed solution enters a centrifuge (C1) through a first centrifuge feed inlet (9) for centrifugal separation; the sulfuric acid of the separated heavy component is output through a water phase discharge port (11) of a first centrifuge; the obtained organic phase (crude product mixed nitrobenzene) enters a second centrifuge (C2) through a first feeding hole (10) of the second centrifuge, and is fully mixed with water with a metered amount which is conveyed to a second feeding hole (12) of the second centrifuge through a pump at the lower end of the centrifuge (C2) for centrifugal separation; the separated water phase is output from a water phase discharge port (14) of the second centrifuge, the obtained organic phase enters a third centrifuge (C3) through a first feed port (13) of the third centrifuge, and is fully mixed with the soda solution conveyed to a second feed port (17) of the third centrifuge through a pump at the lower end of the centrifuge (C3) for centrifugal separation; the separated water phase is output from a water phase discharge port (19) of the third centrifuge, the obtained organic phase enters a fourth centrifuge (C4) through a first feed port (18) of the fourth centrifuge, and is fully mixed with water conveyed to a second feed port (20) of the fourth centrifuge through a pump at the lower end of the centrifuge (C4) for centrifugal separation; the separated water phase is output from a fourth centrifuge organic phase discharge port (22), and the obtained organic phase is output from a fourth centrifuge water phase discharge port (21);
in the embodiment, the mass ratio of nitrobenzene to nitric acid in the mixed acid is 1: 1.05; in the 1-methyl-3-methylimidazole chloride ionic liquid, the amount of the salt is 4 percent of the mass of nitric acid for reaction; the mass content of nitric acid and the mass content of sulfuric acid in the mixed acid are respectively 18% and 76%; adding the used mixed acid into a microchannel reactor for 3 times, wherein the adding proportion is 43 wt% to 42 wt% to 15 wt% according to the total adding amount; the water of the second feed inlet (8) enters the microchannel reactor for 2 times, and the water consumption ratio of 2 times is 3: 2; the mass percentage concentration of the diluted sulfuric acid is 70 percent; the temperature of the nitration reaction is controlled at 81 ℃, and the pressure is controlled at 1.1 MPa;
in the embodiment, in order to keep the reaction temperature relatively stable, the heating section jacket layer of the microreactor is preferably maintained at a certain temperature by hot water at a certain temperature entering from a heating medium inlet (23) of the microreactor, and the hot water flows out from a heating medium outlet (24);
in the embodiment, the concentration of the sulfuric acid output from the water phase discharge port (11) of the first centrifuge is 70%, and the sulfuric acid is concentrated by the acid concentration device and then continuously recycled as concentrated acid.
In the present example, in the second centrifuge (C2), the mass ratio of organic matter to water at the second feed inlet (12) of the second centrifuge is 1: 0.20; in the third centrifuge (C3), the concentration of the soda solution at the second feeding port (17) is 10 wt%; the mass ratio of the organic matter to the soda solution is 1: 0.19; in a fourth centrifuge (C4), the mass ratio of the organic matters to the water at the feed inlet (20) of the second fourth centrifuge is 1: 0.25;
in this embodiment, in order to ensure the temperature is relatively stable during centrifugation, the outer jacket layer of the centrifuge is maintained at a certain temperature by using hot water to prevent the mixed dinitrobenzene from solidifying.
Example 5
The same as example 1 except that a tubular reactor was used for the nitration reaction.
Example 6
The same as example 2 except that a tubular reactor was used for the nitration reaction.
Example 7
The same as example 3 except that a tubular reactor was used for the nitration reaction.
Example 8
The same as example 4 except that a tubular reactor was used for the nitration reaction.
Comparative example 1
A metering pump is adopted to add nitrobenzene into a first-stage kettle and add mixed acid of nitric acid and sulfur into a third-stage kettle of 3-stage reaction kettles which are continuously connected in series, and in order to maintain stable reaction and prevent over violent reaction, the nitrobenzene and the mixed acid adopt reverse flow. After the completion of the above reaction, the separated lower acid was diluted 1 time in a dilution tower and separated, and the lower sulfuric acid concentration was maintained at 65%. And 3 towers are connected in series, the separated upper-layer organic matter is sequentially subjected to pre-washing, alkali washing and final washing by using water, soda ash solution and water, the flow direction of the organic matter and a detergent is countercurrent during washing, namely, a water-phase detergent enters from the lower part of the tower and is retained from the upper part, and an organic phase flows out from the lower layer.
The mass ratio of the nitrobenzene to the nitric acid in the mixed acid is 1:1.05, the mass content of the nitric acid in the prepared mixed acid is 14 percent, the mass content of the sulfuric acid is 80 percent, the reaction temperature is 75-85 ℃, and the pressure is normal pressure.
The washing liquid of the pre-washing, the alkali washing and the final washing are respectively water, 5% of soda solution and water, and the mass ratio of the organic matter to the washing reagent in the pre-washing, the alkali washing and the final washing is respectively 1:0.12, 1:0.11 and 1: 0.11.
Comparative example 2
A metering pump is adopted to add nitrobenzene into a first-stage kettle and add mixed acid of nitric acid and sulfur into a third-stage kettle of 3-stage reaction kettles which are continuously connected in series, and in order to prevent the reaction from being too violent, the nitrobenzene and the mixed acid keep reverse flow. After the completion of the reaction, the separated lower acid was diluted 1 time in a dilution tower and separated, and the lower sulfuric acid concentration was maintained at 70%. And 3 towers are connected in series, the separated upper-layer organic matter is sequentially subjected to pre-washing, alkali washing and final washing by using water, soda ash solution and water, the flow direction of the organic matter and a detergent is countercurrent during washing, namely, a water-phase detergent enters from the lower part of the tower and is retained from the upper part, and an organic phase flows out from the lower layer.
The mass ratio of the nitrobenzene to the nitric acid in the mixed acid is 1:1.08, the mass content of the nitric acid in the prepared mixed acid is 19 percent, the mass content of the sulfuric acid is 77 percent, the reaction temperature is 75-85 ℃, and the pressure is normal pressure.
The washing liquid of the pre-washing, the alkali washing and the final washing are respectively water, 10% of soda solution and water, and the mass ratio of the organic matter to the washing reagent in the pre-washing, the alkali washing and the final washing is respectively 1:0.2, 1:0.19 and 1: 0.2.
Comparative example 3
Nitrobenzene is added into a first-stage kettle and mixed acid of nitric acid and sulfur is added into a third-stage kettle of 3-stage reaction kettles which are continuously connected in series by adopting a metering pump, in order to prevent the reaction from being too violent, the nitrobenzene and the mixed acid keep reverse flow, the reaction temperature is 75-85 ℃, and the pressure is normal pressure. After the completion of the above reaction, the separated lower acid was diluted 1 time in a dilution tower and separated, and the lower sulfuric acid concentration was maintained at 75%. And 3 towers are connected in series, the separated upper-layer organic matter is sequentially subjected to pre-washing, alkali washing and final washing by using water, soda ash solution and water, the flow direction of the organic matter and a detergent is countercurrent during washing, namely, a water-phase detergent enters from the lower part of the tower and is retained from the upper part, and an organic phase flows out from the lower layer.
The mass ratio of the nitrobenzene to the nitric acid in the mixed acid is 1:1.1, and the mass content of the nitric acid and the mass content of the sulfuric acid in the prepared mixed acid are 24% and 69%.
The washing liquid of the pre-washing, the alkali washing and the final washing are respectively water, 15% of soda solution and water, and the mass ratio of the organic matter to the washing reagent in the pre-washing, the alkali washing and the final washing is respectively 1:0.28, 1:0.26 and 1: 0.28.
Results of the experiment
The experimental results of examples 1-8 and comparative examples 1-3 are summarized in Table 1:
TABLE 1 Experimental results of mixed dinitrobenzene production
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. The production method of the mixed dinitrobenzene is characterized by comprising the following steps:
mixing a mixture of nitrobenzene and 1-alkyl-3-methylimidazolium salt ionic liquid with acid liquor, and feeding the mixture into a main feed inlet of a microreactor for partial nitration reaction; then mixing the mixture with acid liquor added into the microreactor through the first feed inlet to perform complete nitration reaction; then mixing with water added into the microreactor through a second feed inlet for dilution; then discharging the microreactor from a discharge hole;
the product of the microreactor discharged from the discharge port enters a first centrifuge for centrifugal separation, and the obtained organic phase is subjected to centrifugal washing sequentially through a second centrifuge, a third centrifuge and a fourth centrifuge to obtain mixed dinitrobenzene;
the centrifugal washing step specifically comprises the following steps: sending the organic phase obtained by centrifugation in the first centrifuge into a first feed port of a second centrifuge, mixing the organic phase with water added through a second feed port of the second centrifuge, and then carrying out centrifugal prewashing; feeding the organic phase obtained by centrifugal prewashing into a first feed inlet of a third centrifuge, mixing the organic phase with alkali liquor added through a second feed inlet of the third centrifuge, and then carrying out centrifugal alkali washing; sending an organic phase obtained by the centrifugal alkaline washing into a first feeding hole of a fourth centrifuge, mixing the organic phase with water added through a second feeding hole of the fourth centrifuge, and then carrying out centrifugal final washing, wherein the obtained organic phase is discharged out of the centrifuge from an organic phase discharging hole of the fourth centrifuge; and in the centrifugal washing process, the water phase is discharged out of the centrifuge from a water phase discharge port of the centrifuge.
2. The production method according to claim 1, wherein the microreactor is a microchannel reactor or a tubular reactor.
3. The production method according to claim 1, wherein the mass ratio of nitrobenzene to nitric acid in the acid solution for reaction is 1: (1.05-1.1).
4. The production method according to claim 1, wherein the alkyl group in the 1-alkyl-3-methylimidazolium salt is a methyl group, an ethyl group, a propyl group or a butyl group, and the anion in the salt is a chloride ion, a nitrate ion or a bisulfate ion;
the dosage of the 1-alkyl-3-methylimidazolium salt is 0.4-9 wt% of the mass of nitric acid in the acid solution for reaction.
5. The production method according to claim 1, wherein the acid solution for performing the partial nitrification reaction and the complete nitrification reaction is added to the microreactor in 2 to 3 times; when the acid liquor is added for 2 times, the adding proportion is (53-70) wt% according to the total adding amount of the acid liquor: (47-30) wt%, the total addition amount being 100 wt%; when the materials are added for 3 times, the adding proportion is (43-51) wt%: (31-42) wt%: (7-26) wt%, the total amount added being 100 wt%.
6. The production method according to claim 1, wherein the acid solution used for the partial nitrification reaction and the complete nitrification reaction is a mixed acid solution containing nitric acid and sulfuric acid, wherein the mass content of nitric acid is 14-24%, and the mass content of sulfuric acid is 69-83%.
7. The production method according to claim 1, characterized in that: the temperature of the partial nitrification reaction and the temperature of the complete nitrification reaction are independently selected to be 76-85 ℃, and the pressure of the partial nitrification reaction and the pressure of the complete nitrification reaction are independently selected to be 0.8-1.3 MPa.
8. The production method according to claim 1, characterized in that: after the dilution, the mass percentage concentration of the sulfuric acid in the system is 65-75%.
9. The production method according to claim 1, wherein the alkali liquor is a 5-15 wt% soda ash solution.
10. The production method according to claim 1, wherein in the centrifugal prewashing process, the mass ratio of the organic phase to the water is 1: (0.12-0.28); in the centrifugal alkali washing process, the mass ratio of the organic phase to the alkali liquor is 1: (0.11-0.26); in the centrifugal final washing process, the mass ratio of the organic phase to the water is 1: (0.11-0.28).
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