WO2024001054A1 - 一种硝基苯的生产方法 - Google Patents

一种硝基苯的生产方法 Download PDF

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WO2024001054A1
WO2024001054A1 PCT/CN2022/137440 CN2022137440W WO2024001054A1 WO 2024001054 A1 WO2024001054 A1 WO 2024001054A1 CN 2022137440 W CN2022137440 W CN 2022137440W WO 2024001054 A1 WO2024001054 A1 WO 2024001054A1
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centrifuge
feed port
washing
acid
microreactor
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PCT/CN2022/137440
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English (en)
French (fr)
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马海兵
梁玉龙
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宁夏信广和新材料科技有限公司
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    • 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
    • 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
    • C07C201/16—Separation; Purification; Stabilisation; Use of additives
    • 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
    • Y02P20/10—Process efficiency

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  • the invention belongs to the field of nitrobenzene production, and particularly relates to a nitrobenzene production method.
  • Nitrobenzene is an important chemical intermediate, used as a raw material for the production of aniline, and also used in the production of dyes, spices, explosives and other organic synthesis industries.
  • kettle-type reactors At present, most domestic enterprises use kettle-type reactors to produce nitrobenzene.
  • kettle-type reactors generally the volume of a single tank is ⁇ 10m 3
  • the large amount of materials in them once an accident occurs, it is very dangerous. big.
  • the tower since the tower is used for separation, and the tower has a large volume and a large amount of stock, there are great safety risks. Therefore, it is very important to find an industrial production method of nitrobenzene with wide sources of raw materials, intrinsic safety, good selectivity and high efficiency.
  • Microreactor technology originated in Europe in the early 1990s. Its reactor channel size is micron-scale. Compared with traditional reactors, microreactors have shorter molecular diffusion distances, faster mass transfer, laminar flow in the channels, and narrow residence time distribution. , no back-mixing, large specific surface area per unit volume, fast heat transfer speed, strong heat exchange capacity, and easy temperature control. Microreactors include microchannel reactors, tubular reactors and other similar reactors.
  • Patent CN101613285 discloses a method for preparing nitrobenzene using a tubular reactor, but a kettle-type stirring device is used after the reaction. Although the liquid volume in the microchannel reaction part is small, the subsequent existence of the stirring kettle increases. The amount of liquid stored is not conducive to the safety of nitrification. In addition, the nitrobenzene produced is crude nitrobenzene containing acid and has not been purified.
  • the object of the present invention is to provide a production method of nitrobenzene.
  • the method adopted in the scheme of the present invention has the advantages of high nitrobenzene yield, intrinsically safe process, and high processing efficiency.
  • the invention provides a production method of nitrobenzene, which includes the following steps:
  • Benzene and the acid solution are mixed and sent to the main feed port of the microreactor to perform a partial nitration reaction; then mixed with the acid solution added into the microreactor through the first feed port to perform a complete nitrification reaction; and then mixed with the acid solution added to the microreactor through the first feed port to perform a complete nitration reaction.
  • the second feed port is added to the water in the microreactor to mix and dilute; then the microreactor is discharged from the outlet;
  • the product discharged from the microreactor from the discharge port enters the first centrifuge for centrifugal separation, and the resulting organic phase is centrifugally washed by the second, third and fourth centrifuges in sequence to obtain nitrobenzene;
  • the step of centrifugal washing is specifically: sending the organic phase obtained by centrifugation in the first centrifuge into the first feed port of the second centrifuge, and mixing it with water added through the second feed port of the second centrifuge. Then perform centrifugal pre-washing; the organic phase obtained by centrifugal pre-washing is sent to the first feed port of the third centrifuge, mixed with the alkali solution added through the second feed port of the third centrifuge, and then centrifuged for alkali washing; centrifugal alkali washing
  • the organic phase obtained by washing is sent to the first feed port of the fourth centrifuge, mixed with the water added through the second feed port of the fourth centrifuge, and then centrifuged for final washing.
  • the organic phase obtained is from the organic phase of the fourth centrifuge.
  • the discharge port discharges the centrifuge; during the centrifugal washing process, the water phase is discharged from the centrifuge through the water phase discharge port of the centrifuge.
  • the microreactor is a microchannel reactor or a tubular reactor.
  • the acid liquid used to carry out the partial nitration reaction and the complete nitration reaction is a mixed acid liquid containing nitric acid and sulfuric acid, in which the mass content of nitric acid is 25-38% and the mass content of sulfuric acid is 52-66%.
  • the substance ratio between benzene and nitric acid in the acid solution used for the reaction is 1: (1.05-1.1).
  • the acid liquid used to carry out the partial nitration reaction and the complete nitration reaction is added to the microreactor in 2 to 3 times.
  • the successive addition ratios are (55-68) wt%: (45-32) wt%, and the total added amount is 100wt%; added in 3 times
  • the successive addition ratios are (45 ⁇ 52)wt%: (33 ⁇ 40)wt%: (8 ⁇ 22)wt%, and the total addition amount is 100wt%.
  • the temperatures of the partial nitrification reaction and the complete nitrification reaction are independently selected from 40 to 48°C, and the pressures of the partial nitrification reaction and the complete nitrification reaction are independently selected from 0.9 to 1.4 MPa.
  • the mass concentration of sulfuric acid in the system is 60-75%.
  • the alkali solution is a 5-15 wt% soda ash solution.
  • the mass ratio of the organic phase to water is 1: (0.11-0.28); during the centrifugal alkali washing process, the mass ratio of the organic phase to alkali solution is 1: (0.12-0.24). ); During the final centrifugal washing process, the mass ratio of the organic phase to water is 1: (0.11 ⁇ 0.26).
  • the present invention provides a production method of nitrobenzene, which includes the following steps: mixing benzene and acid and sending it to a microreactor for nitration reaction; and then sending it to a centrifuge for centrifugation, and the obtained organic phase is sequentially Pre-washing, alkali washing, and final washing are carried out through the second, third, and fourth centrifuges, and the nitrobenzene obtained by the final centrifugal washing is discharged from the organic phase outlet of the fourth centrifuge.
  • the invention provides a process for continuously producing nitrobenzene by performing nitrification and dilution in a microreactor and washing and separating with a centrifuge.
  • Figure 1 is a flow chart of the nitrobenzene production process provided by the embodiment of the present invention.
  • T1 is a benzene buffer device
  • T2 is an acid buffer device
  • T3 is an acid diluent buffer device
  • T4 is a pre-wash buffer device
  • T5 is an alkali buffer device
  • T6 is a final wash buffer device.
  • C1 is the first centrifuge
  • C2 is the second centrifuge
  • C3 is the third centrifuge
  • C4 is the fourth centrifuge.
  • 1 is the heat medium feed port of the jacket layer of the heating section of the microreactor
  • 2 is the benzene buffer device.
  • Feed port, 3 is the first feed port of the acid buffer device, 4 is the second feed port of the acid buffer device, 5 is the feed port of the acid diluent buffer device, 6 is the main feed port of the microreactor, 7 is the first feed port of the microreactor, 8 is the second feed port of the microreactor, 9 is the first feed port of the centrifuge, 10 is the first feed port of the second centrifuge, 11 is The water phase discharge port of the first centrifuge, 12 is the second feed port of the second centrifuge, 13 is the first feed port of the third centrifuge, 14 is the water phase discharge port of the second centrifuge, 15 is the first feed port of the alkali buffer device, 16 is the second feed port of the alkali buffer device, 17 is the second feed port of the third centrifuge, and 18 is the first feed port of the fourth centrifuge.
  • the outlet, 23, is the heat medium outlet of the jacket layer of the heating section of the microreactor.
  • the invention provides a production method of nitrobenzene.
  • the nitration reaction is carried out in a microreactor, the mixture obtained by the nitration reaction is diluted with water and centrifugally separated to obtain crude nitrobenzene.
  • the crude nitrobenzene is centrifugally washed, which effectively improves the production efficiency of nitrobenzene. Conversion rate, reaction efficiency and product purity, the specific process is as follows:
  • the mass content of nitric acid is preferably 25% to 38%; the mass content of sulfuric acid is preferably 52% to 68%; and the material ratio of benzene to nitric acid is preferably 1:(1.05-1.1).
  • the acid buffer device (T2) is equipped with a jacket, and condensed water is passed through the jacket to dissipate the heat generated during mixing.
  • the alkali buffer device (T5) Under stirring, add soda ash and water according to a certain ratio to the alkali buffer device (T5) from the first feed port (15) of the alkali buffer device and the second feed port (16) of the alkali buffer device.
  • the alkali solution is preferably a 5% to 15% soda ash solution.
  • the alkali buffer device (T5) is equipped with a jacket, and condensed water is passed through the jacket to dissipate the heat generated during mixing.
  • the benzene in the benzene cache device (T1) and the mixed acid in the acid solution cache device (T2) are pumped to the main feed port (6) of the microreactor and enter the microreactor for nitration reaction. At this time, part of the benzene and Part of the nitric acid completes the nitration; then, the mixed liquid after the nitration reaction continues to be completely nitrated with the mixed acid entering the microreactor through the first feed port (7) to obtain a mixed liquid after the complete nitration reaction.
  • the main components of the mixed liquid are nitrobenzene and a small amount of unreacted nitric acid and catalytic sulfuric acid.
  • the jacket layer of the heating section of the microreactor preferably maintains the temperature by using hot water of a certain temperature entering from its heat medium feed port (1), and the hot water exits from the heat medium.
  • the material flows out from the material port (23).
  • the mixed acid added to the main feed port (6) and the first feed port (7) of the microreactor can be added to the microreactor in 2 to 3 times; calculated according to the total input amount, it can be added in 2 times
  • the preferred adding ratio is (55-68) wt%: (45-32) wt%, and the total added amount is 100wt%; when adding in three times, the preferred adding ratio is (45-52) wt%: (33 ⁇ 40)wt%: (8 ⁇ 22)wt%, the total added amount is 100wt%.
  • the temperature during the nitration reaction is preferably controlled at 40 to 48°C, and the pressure during the nitration reaction is preferably controlled at 0.9 to 1.4 MPa.
  • the heating section jacket layer of the microreactor preferably maintains the temperature by hot water of a certain temperature entering from its heat medium feed port (1), and the hot water exits from the heat medium.
  • the material flows out from the material port (23).
  • the number of dilutions is preferably 1 to 3 times.
  • the concentration of sulfuric acid after dilution is preferably 60% to 75%.
  • the diluted mixed liquid enters the centrifuge (C1) through the first centrifuge feed port (9) for centrifugal separation, and the separated heavy component sulfuric acid is output through the first centrifuge water phase outlet (11); the resulting organic
  • the phase (crude nitrobenzene) is output through the discharge port of the first centrifuge, and then enters the second centrifuge (C2) through the first feed port (10) of the second centrifuge.
  • the output liquid from the water phase outlet (11) of the first centrifuge is preferably 60% to 75% sulfuric acid. After being concentrated by an acid concentration device, the sulfuric acid can be recycled as concentrated acid.
  • the outer jacket layer of the centrifuge uses hot water of a certain temperature to maintain the temperature to prevent the solidification of nitrobenzene.
  • the crude nitrobenzene obtained by the above separation is continuously fed into a centrifuge for centrifugal washing.
  • the sequence of centrifugal washing is pre-wash, alkali wash and final wash, specifically:
  • Pre-washing The above-mentioned crude nitrobenzene transported to the first feed port (10) of the second centrifuge and the measured amount of water transported to the second feed port (12) of the second centrifuge through the pump are placed in the centrifuge. (C2) The lower end is thoroughly mixed, and then centrifuged. The aqueous phase obtained by separation is output from the aqueous phase outlet (14) of the second centrifuge; the organic phase (prewashed nitrobenzene) is output and then enters the third centrifuge through the first feed inlet (13) of the third centrifuge. Centrifuge (C3). Through this continuous pre-washing, most of the acid dissolved in the crude nitrobenzene can be washed away.
  • Alkali washing the above-mentioned pre-washed nitrobenzene transported to the first feed port (13) of the third centrifuge and the excess soda ash solution transported to the second feed port (17) of the third centrifuge through a pump, The lower end of the centrifuge (C3) is thoroughly mixed and then centrifuged.
  • the aqueous phase obtained by separation is output from the aqueous phase outlet (19) of the third centrifuge; the organic phase (nitrobenzene after alkali washing) is output and then enters the fourth centrifuge through the first feed inlet (18) of the fourth centrifuge. Centrifuge (C4). Through this continuous alkali washing, all the acid in nitrobenzene can be washed away.
  • the outer jacket layer of the centrifuge uses hot water of a certain temperature to maintain the temperature to prevent nitrobenzene from solidifying.
  • the mass ratio of organic matter to washing reagent water is preferably 1: (0.11-0.28); in the alkali washing process, the detergent is preferably a 5-15% soda ash solution, and the organic matter and washing reagent soda ash solution
  • the mass ratio of organic matter to washing reagent water is preferably 1:(0.12 ⁇ 0.24); during the final washing process, the mass ratio of organic matter to washing reagent water is preferably 1:(0.11 ⁇ 0.26).
  • Microreactors are used in the reactor and diluter types, which overcomes the major safety problems caused by the large liquid volume in traditional kettle-type reactions, and has Advantages of intrinsic safety.
  • the residence time of materials in the microreactor is about 5 to 15 seconds, which overcomes the shortcoming of the residence time of more than 30 minutes in traditional kettle reactors, and has the characteristics of significantly fast reaction speed and high reaction efficiency;
  • the nitrification reaction is carried out in a microchannel reactor.
  • the process flow is shown in Figure 1.
  • the specific process is:
  • the benzene and mixed acid are transported to the main feed port (6) of the microchannel reactor through a pump and enter the microchannel reactor for nitration reaction. At this time, part of the benzene and part of the nitric acid complete the nitration; then, the mixed liquid after the nitration reaction continues Complete nitrification is performed with the mixed acid that enters the microchannel reactor through the first feed port (7) to obtain a mixed liquid after complete nitration reaction; the aforementioned mixed liquid is combined with the acid diluent buffer device in the second feed port (8)
  • the water transported in (T3) is mixed and enters the microchannel reactor to dilute the sulfuric acid; the diluted mixed liquid enters the centrifuge (C1) through the first centrifuge feed port (9) for centrifugal separation; the resulting recombination is separated
  • the separated sulfuric acid is output through the aqueous phase outlet (11) of the first centrifuge; the obtained organic phase (crude nitrobenzene) enters the second
  • the obtained organic phase enters the third centrifuge (C3) through the first feed port (13) of the third centrifuge, and the soda ash solution transported to the second feed port (17) of the third centrifuge through a pump, Mix thoroughly at the lower end of the centrifuge (C3) for centrifugal separation; the separated aqueous phase is output from the aqueous phase outlet (19) of the third centrifuge, and the obtained organic phase enters the third centrifuge through the first inlet (18).
  • the fourth centrifuge (C4) is fully mixed with the water delivered to the second feed port (20) of the fourth centrifuge through the pump at the lower end of the centrifuge (C4) for centrifugal separation; the separated aqueous phase is organically separated from the fourth centrifuge.
  • the phase outlet (22) is output, and the obtained organic phase is output from the water phase outlet (21) of the fourth centrifuge;
  • the mass content of nitric acid in the mixed acid is 25%, and the mass content of sulfuric acid is 66%.
  • the mass ratio of benzene and nitric acid in the mixed acid is 1:1.05; the mixed acid used is added to the microchannel reactor in two batches, and the total amount is added Calculating the amount, the ratio of mixed acid added twice is 55wt%:45wt%; the water from the second feed port (8) enters the microchannel reactor in three times, and the water dosage ratio for the three times is 2:3:5 ;
  • the mass concentration of sulfuric acid after dilution is 60%; the nitrification reaction temperature is controlled at 40°C and the pressure is controlled at 0.9MPa;
  • the heating section jacket layer of the microreactor is preferably maintained by hot water of a certain temperature entering from its heat medium feed port (1).
  • the hot water is supplied from the heat medium.
  • the concentration of sulfuric acid output from the water phase outlet (11) of the first centrifuge is 60%. After being concentrated by the acid concentration device, it is continued to be recycled as concentrated acid;
  • the mass ratio of organic matter to water in the second feed port (12) of the second centrifuge is 1:0.11; in the third centrifuge (C3), the The concentration of the soda ash solution in the second feed port (17) is 5wt%; the mass ratio of the organic matter to the aforementioned soda ash solution is 1:0.12; in the fourth centrifuge (C4), the organic matter and the second feed port (C4) of the fourth centrifuge are 20) The mass ratio of water is 1:0.11;
  • the outer jacket layer of the centrifuge uses hot water of a certain temperature to maintain the temperature to prevent nitrobenzene from solidifying.
  • the nitrification reaction is carried out in a microchannel reactor.
  • the process flow is shown in Figure 1.
  • the specific process is:
  • the benzene and mixed acid are transported to the main feed port (6) of the microchannel reactor through a pump and enter the microchannel reactor for nitration reaction. At this time, part of the benzene and part of the nitric acid complete the nitration; then, the mixed liquid after the nitration reaction continues Complete nitrification is performed with the mixed acid that enters the microchannel reactor through the first feed port (7) to obtain a mixed liquid after complete nitration reaction; the aforementioned mixed liquid is combined with the acid diluent buffer device in the second feed port (8)
  • the water transported in (T3) is mixed and enters the microchannel reactor to dilute the sulfuric acid; the diluted mixed liquid enters the centrifuge (C1) through the first centrifuge feed port (9) for centrifugal separation; the resulting recombination is separated
  • the separated sulfuric acid is output through the aqueous phase discharge port (11) of the first centrifuge; the obtained organic phase (crude nitrobenzene) enters the
  • the soda ash solution in the second feed port (17) is fully mixed at the lower end of the centrifuge (C3) and centrifugally separated; the separated aqueous phase is output from the third centrifuge water phase outlet (19); the obtained organic phase (after alkali washing Nitrobenzene) enters the fourth centrifuge (C4) through the first feed port (18) of the fourth centrifuge, and with the water transported to the second feed port (20) of the fourth centrifuge through the pump, in the centrifuge (C4) The lower end is thoroughly mixed and centrifuged; the separated aqueous phase is output from the fourth centrifuge organic phase outlet (22); the obtained organic phase is output from the fourth centrifuge aqueous phase outlet (21);
  • the mass content of nitric acid in the mixed acid is 38%, and the mass content of sulfuric acid is 52%.
  • the mass ratio of benzene and nitric acid in the mixed acid is 1:1.1; the mixed acid used is added to the microchannel reactor in two batches, and the total amount is added Calculate the amount, the ratio of mixed acid added twice is 68wt%:32wt%; the water from the second feed port (8) enters the microchannel reactor in two times, and the water dosage ratio for the two times is 3:2; dilution
  • the final mass concentration of sulfuric acid is 75%; the nitrification reaction temperature is controlled at 48°C and the pressure is controlled at 1.4MPa;
  • the heating section jacket layer of the microreactor is preferably maintained by hot water of a certain temperature entering from its heat medium feed port (1).
  • the hot water is supplied from the heat medium.
  • the sulfuric acid concentration output from the water phase outlet (11) of the first centrifuge is 75%. After being concentrated by the acid concentration device, it is continued to be recycled as concentrated acid;
  • the mass ratio of organic matter to water in the second feed port (12) of the second centrifuge is 1:0.28; in the third centrifuge (C3), the mass ratio of The concentration of the soda ash solution in the second feed port (17) is 15wt%; the mass ratio of the organic matter to the aforementioned soda ash solution is 1:0.24; in the fourth centrifuge (C4), the organic matter and the second feed port (C4) of the fourth centrifuge are 20) The mass ratio of water is 1:0.26;
  • the outer jacket layer of the centrifuge uses hot water of a certain temperature to maintain the temperature to prevent nitrobenzene from solidifying.
  • the nitrification reaction is carried out in a microchannel reactor.
  • the process flow is shown in Figure 1.
  • the specific process is:
  • the benzene and mixed acid are transported to the main feed port (6) of the microchannel reactor through a pump and enter the microchannel reactor for nitration reaction. At this time, part of the benzene and part of the nitric acid complete the nitration; then, the mixed liquid after the nitration reaction continues Complete nitrification is performed with the mixed acid that enters the microchannel reactor through the first feed port (7) to obtain a mixed liquid after complete nitration reaction; the aforementioned mixed liquid is combined with the acid diluent buffer device in the second feed port (8)
  • the water transported in (T3) is mixed and enters the microchannel reactor to dilute the sulfuric acid; the diluted mixed liquid enters the centrifuge (C1) through the first centrifuge feed port (9) for centrifugal separation; the resulting recombination is separated
  • the separated sulfuric acid is output through the aqueous phase outlet (11) of the first centrifuge; the obtained organic phase (crude nitrobenzene) enters the second
  • the soda ash solution in the second feed port (17) is fully mixed at the lower end of the centrifuge (C3) and centrifugally separated; the separated aqueous phase is output from the third centrifuge water phase outlet (19); the obtained organic phase (after alkali washing) nitrobenzene) enters the fourth centrifuge (C4) through the first feed port (18) of the fourth centrifuge, and with the water transported to the second feed port (20) of the fourth centrifuge through the pump, in the centrifuge (C4) The lower end is fully mixed and centrifuged; the separated aqueous phase is output from the fourth centrifuge organic phase outlet (22); the obtained organic phase is output from the fourth centrifuge aqueous phase outlet (21);
  • the mass content of nitric acid in the mixed acid is 30%, and the mass content of sulfuric acid is 59%.
  • the mass ratio of benzene and nitric acid in the mixed acid is 1:1.08; the mixed acid used is added to the microchannel reactor in two batches, and the total amount is added According to the volume calculation, the ratio of mixed acid added twice is 70wt%:30wt%; the water from the second feed port (8) enters the microchannel reactor once, and the mass percentage concentration of sulfuric acid after dilution is 70%;
  • the nitrification reaction temperature is controlled at 45°C and the pressure is controlled at 1.0MPa;
  • the heating section jacket layer of the microreactor is preferably maintained by hot water of a certain temperature entering from its heat medium feed port (1).
  • the hot water is supplied from the heat medium.
  • the concentration of sulfuric acid output from the water phase outlet (11) of the first centrifuge is 70%. After being concentrated by the acid concentration device, it is continued to be recycled as concentrated acid;
  • the mass ratio of organic matter to water in the second feed port (12) of the second centrifuge is 1:0.20; in the third centrifuge (C3), the mass ratio of The concentration of the soda ash solution in the second feed port (17) is 10wt%; the mass ratio of the organic matter to the aforementioned soda ash solution is 1:0.18; in the fourth centrifuge (C4), the organic matter and the second feed port (C4) of the fourth centrifuge are 20) The mass ratio of water is 1:0.19;
  • the outer jacket layer of the centrifuge uses hot water of a certain temperature to maintain the temperature to prevent nitrobenzene from solidifying.
  • the nitrification reaction is carried out in a microchannel reactor.
  • the process flow is shown in Figure 1.
  • the specific process is:
  • the benzene and mixed acid are transported to the main feed port (6) of the microchannel reactor through a pump and enter the microchannel reactor for nitration reaction. At this time, part of the benzene and part of the nitric acid complete the nitration; then, the mixed liquid after the nitration reaction continues Complete nitrification is performed with the mixed acid that enters the microchannel reactor through the first feed port (7) to obtain a mixed liquid after complete nitration reaction; the aforementioned mixed liquid is combined with the acid diluent buffer device in the second feed port (8)
  • the water transported in (T3) is mixed and enters the microchannel reactor to dilute the sulfuric acid; the diluted mixed liquid enters the centrifuge (C1) through the first centrifuge feed port (9) for centrifugal separation; the resulting recombination is separated
  • the separated sulfuric acid is output through the aqueous phase outlet (11) of the first centrifuge; the obtained organic phase (crude nitrobenzene) enters the second
  • the soda ash solution in the second feed port (17) is fully mixed at the lower end of the centrifuge (C3) and centrifugally separated; the separated aqueous phase is output from the third centrifuge water phase outlet (19); the obtained organic phase (after alkali washing nitrobenzene) enters the fourth centrifuge (C4) through the first feed port (18) of the fourth centrifuge, and with the water transported to the second feed port (20) of the fourth centrifuge through the pump, in the centrifuge (C4)
  • the lower end is fully mixed and centrifuged; the separated aqueous phase is output from the fourth centrifuge organic phase outlet (22); the obtained organic phase is output from the fourth centrifuge aqueous phase outlet (21);
  • the mass content of nitric acid in the mixed acid is 31%, and the mass content of sulfuric acid is 59%.
  • the mass ratio of benzene and nitric acid in the mixed acid is 1:1.08; the mixed acid used is added to the microchannel reactor in three times, and the total amount is calculated according to the total amount. According to the calculation of the amount, the ratio of the mixed acid added twice is 45wt%:42wt%:13wt%; the water from the second feed port (8) enters the microchannel reactor in two times, and the water dosage ratio for the two times is 2: 3;
  • the mass concentration of sulfuric acid after dilution is 70%; the nitrification reaction temperature is controlled at 41°C and the pressure is controlled at 1.1MPa;
  • the heating section jacket layer of the microreactor is preferably maintained by hot water of a certain temperature entering from its heat medium feed port (1).
  • the hot water is supplied from the heat medium.
  • the concentration of sulfuric acid output from the water phase outlet (11) of the first centrifuge is 70%. After being concentrated by the acid concentration device, it is continued to be recycled as concentrated acid;
  • the mass ratio of organic matter to water in the second feed port (12) of the second centrifuge is 1:0.19; in the third centrifuge (C3), the mass ratio of The concentration of the soda ash solution in the second feed port (17) is 10wt%; the mass ratio of the organic matter to the aforementioned soda ash solution is 1:0.17; in the fourth centrifuge (C4), the organic matter and the second feed port (C4) of the fourth centrifuge are 20) The mass ratio of water is 1:0.18;
  • the outer jacket layer of the centrifuge uses hot water of a certain temperature to maintain the temperature to prevent nitrobenzene from solidifying.
  • Example 2 Same as Example 1, except that the reactor is a tubular reactor.
  • Example 2 Same as Example 2, except that the reactor is a tubular reactor.
  • Example 3 Same as Example 3, except that the reactor is a tubular reactor.
  • Example 4 Same as Example 4, except that the reactor is a tubular reactor.
  • nitrobenzene and mixed acid are used in reverse. flow.
  • the separated lower layer acid enters the dilution tower for one dilution and liquid separation, and the lower layer sulfuric acid concentration is maintained at 60%.
  • the separated upper organic matter is sequentially pre-washed, alkali washed and final washed with water, pure alkali and water. During washing, the flow direction of the organic matter and detergent is counter-current, that is, the aqueous detergent enters from the lower part of the tower and exits from the bottom of the tower. The upper part is left, and the organic phase flows out from the lower layer.
  • the mass ratio of the above-mentioned benzene and nitric acid in the mixed acid is 1:1.05, the mass content of nitric acid in the mixed acid is 25%, and the mass content of sulfuric acid is 66%.
  • the reaction temperature is 40°C, and the pressure is normal pressure.
  • the washing liquids of the above-mentioned pre-wash, alkali wash and final wash are water, 5% soda ash solution and water respectively.
  • the mass ratios of organic matter and washing reagents are 1:0.11 and 1:0.12 respectively. , 1:0.11.
  • nitrobenzene and mixed acid Using a metering pump, add nitrobenzene to the first-stage kettle of a continuous series of 3-stage reactors, and add nitrate-sulfur mixed acid to the third-stage kettle. In order to prevent the reaction from being too violent, the nitrobenzene and mixed acid maintain reverse flow.
  • the separated lower layer acid enters the dilution tower for one dilution and liquid separation, and the lower layer sulfuric acid concentration is maintained at 75%.
  • the separated upper organic matter is sequentially pre-washed, alkali washed and final washed with water, pure alkali and water. During washing, the flow direction of the organic matter and detergent is counter-current, that is, the aqueous detergent enters from the lower part of the tower and exits from the bottom of the tower. The upper part is left, and the organic phase flows out from the lower layer.
  • the mass ratio of the above-mentioned benzene and nitric acid in the mixed acid is 1:1.08, the mass content of nitric acid in the prepared mixed acid is 38%, the mass content of sulfuric acid is 52%, the reaction temperature is 48°C, and the pressure is normal pressure.
  • the washing liquids of the above-mentioned pre-wash, alkali wash and final wash are water, 10% soda ash solution and water respectively.
  • the mass ratios of organic matter and washing reagents are 1:0.28 and 1:0.24 respectively. , 1:0.26.
  • nitrobenzene to the first-stage kettle of a continuous series of 3-stage reaction kettles, and add nitrate-sulfur mixed acid to the third-stage kettle.
  • the nitrobenzene and mixed acid maintain reverse flow, and the reaction temperature The temperature is 45°C and the pressure is normal pressure.
  • the separated lower layer acid enters the dilution tower for one dilution and liquid separation, and the lower layer sulfuric acid concentration is maintained at 70%.
  • the separated upper organic matter is sequentially pre-washed, alkali washed and final washed with water, pure alkali and water. During washing, the flow direction of the organic matter and detergent is counter-current, that is, the aqueous detergent enters from the lower part of the tower and exits from the bottom of the tower. The upper part is left, and the organic phase flows out from the lower layer.
  • the mass ratio of the above-mentioned benzene to the nitric acid in the mixed acid is 1:1.1.
  • the mass content of nitric acid in the prepared mixed acid is 24%, and the mass content of sulfuric acid is 69%.
  • the washing liquids of the above-mentioned pre-wash, alkali wash and final wash are water, 15% soda ash solution and water respectively.
  • the mass ratios of organic matter and washing reagents are 1:0.20 and 1:0.18 respectively. , 1:0.21.

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Abstract

本申请属于硝基苯的生产领域，尤其涉及一种硝基苯的生产方法。该方法包括以下步骤：将苯与酸混合后送入微反应器，进行硝化反应；之后送入离心机离心，所得有机相依次通过第二、第三、第四离心机进行预洗、碱洗、终洗，最后离心洗涤所得硝基苯从第四离心机有机相出料口排出离心机。本发明提供了一种通过微反应器进行硝化及稀释，采用离心机洗涤和分离的连续生产硝基苯的新工艺。所用微反应器硝化时，反应过程的传质与传热效果好，离心设备分离效率高。该方法具有本质安全，产品选择性高，生产效率高等优点。

Description

一种硝基苯的生产方法
本申请要求于2022年06月28日提交中国专利局、申请号为202210741547.1、发明名称为“一种硝基苯的生产方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明属于硝基苯的生产领域，尤其涉及一种硝基苯的生产方法。
背景技术
硝基苯是一种重要的化工中间体，用作生产苯胺的原料，也用于生产染料、香料、炸药等有机合成工业。
目前，国内大多企业采用釜式反应器进行生产硝基苯，但由于釜式反应釜体积较大(一般为单釜体积≥10m 3)，其中物料存量较多，一旦发生事故，其危险性很大。同时，在后续分离中，由于采用塔器进行分离，而塔器容积大、其中存量较大，存在很大安全隐患。因此，找到一种原料来源广、本质安全、选择性好、效率较高的硝基苯的工业生产方法非常重要。
微反应技术起源于20世纪90年代初的欧洲，其反应器通道尺寸微米级，相比于传统反应器，微反应器分子扩散距离短、传质快、通道内为层流、停留时间分布窄、无返混、单位体积的比表面积超大、传热速度快、换热能力强、易控温。微反应器包括微通道反应器、管式反应器及其他类似反应器。
由于微反应器本身体积小，使其存液量不大，其特别适用于硝化等危险反应，即使发生危险，其持有的较小液体不会造成更大的严重后果。
专利CN101613285公开了一种采用管式反应器进行制备硝基苯的方法，但在反应后采用了釜式搅拌装置，虽然微通道反应部分存液量较少，但后续搅拌釜的存在又增加了存液量，不利于硝化安全。另外，其制得的硝基苯为含有酸的粗硝基苯，未做纯化。
另外，在传统硝基苯的反应后，一般采用塔式分离，或其他大存液量形式容器进行分离酸和有机物，这也会导致液体在塔器中停留量增加，存在较大安全隐患。
发明内容
有鉴于此，本发明的目的在于提供一种硝基苯的生产方法。本发明方案所采用的方法具有硝基苯收率高，过程本质安全，处理效率高等优点。
本发明提供了一种硝基苯的生产方法，包括以下步骤：
将苯与酸液混合后送入微反应器的主进料口，进行部分硝化反应；随后与通过第一支进料口加入到微反应器内的酸液混合，进行完全硝化反应；接着与通过第二支进料口加入到微反应器内的水混合进行稀释；之后从出料口排出微反应器；
从所述出料口排出微反应器的产物进入第一离心机进行离心分离，所得有机相依次通过第二、第三和第四离心机进行离心洗涤，得到硝基苯；
所述离心洗涤的步骤具体为：将所述第一离心机中离心所得有机相送入第二离心机的第一进料口，与通过第二离心机的第二进料口加入的水混合后进行离心预洗；离心预洗所得有机相送入第三离心机的第一进料口，与通过第三离心机的第二进料口加入的碱液混合后进行离心碱洗；离心碱洗所得有机相送入第四离心机的第一进料口，与通过第四离心机的第二进料口加入的水混合后进行离心终洗，所得有机相从第四离心机的有机相出料口排出离心机；所述离心洗涤的过程中，水相均从离心机的水相出料口排出离心机。
优选的，所述微反应器为微通道反应器或管式反应器。
优选的，进行所述部分硝化反应和完全硝化反应所用的酸液为含有硝酸与硫酸的混合酸液，其中硝酸的质量含量25～38％，硫酸的质量含量52～66％。
优选的，所述苯与反应(部分硝化反应和完全硝化反应)用酸液中硝酸的物质的量比为1：(1.05～1.1)。
优选的，所述，进行所述部分硝化反应和完全硝化反应所用的酸液分2～3次加入微反应器。
优选的，按照所用酸液的总加入量计算，分2次加入时，先后加入比例为(55～68)wt％：(45～32)wt％，合计加入量为100wt％；分3次加入时，先后加入比例为(45～52)wt％：(33～40)wt％：(8～22)wt％，合计加入量为100wt％。
优选的，所述部分硝化反应和和完全硝化反应的温度独立地选择40～48℃， 所述部分硝化反应和和完全硝化反应的压力独立地选择0.9～1.4MPa。
优选的，进行所述稀释后，体系中硫酸的质量百分浓度为60～75％。
优选的，所述碱液为5～15wt％的纯碱溶液。
优选的，所述离心预洗过程中，有机相与水的质量比为1：(0.11～0.28)；所述离心碱洗过程中，有机相与碱液的质量比为1：(0.12～0.24)；所述离心终洗过程中，有机相与水的质量比为1：(0.11～0.26)。
与现有技术相比，本发明提供了一种硝基苯的生产方法，包括以下步骤：将苯与酸混合后送入微反应器，进行硝化反应；之后送入离心机离心，所得有机相依次通过第二、第三、第四离心机进行预洗、碱洗、终洗，最后离心洗涤所得硝基苯从第四离心机有机相出料口排出离心机。本发明提供了一种通过微反应器进行硝化及稀释，采用离心机洗涤和分离的连续生产硝基苯的工艺方法。所用微反应器硝化时，反应过程的传质与传热效果好，离心设备分离效率高。该方法具有本质安全，产品选择性高，生产效率高等优点，市场前景广阔。
附图说明
图1是本发明实施例提供的硝基苯生产工艺流程图。
附图中标记如下：T1为苯缓存装置，T2为酸液缓存装置，T3为酸稀释液缓存装置，T4为预洗液缓存装置，T5为碱液缓存装置，T6为终洗液缓存装置，C1为第一离心机、C2为第二离心机、C3为第三离心机、C4为第四离心机，1为微反应器加热段夹套层的热媒进料口，2为苯缓存装置进料口，3为酸液缓存装置第一进料口，4为酸液缓存装置第二进料口，5为酸稀释液缓存装置进料口，6为微反应器的主进料口，7为微反应器的第一支进料口，8为微反应器的第二支进料口，9为第一离心机进料口，10第二离心机的第一进料口，11为第一离心机的水相出料口，12为第二离心机的第二进料口，13为第三离心机的第一进料口，14为第二离心机的水相出料口，15为碱液缓存装置的第一进料口，16为碱液缓存装置的第二进料口，17为第三离心机的第二进料口，18为第四离心机的第一进料口，19为第三离心机的水相出料口，20为第四离心机的第二进料口，21为第四离心机的有机相出料口，22为第四离心机的水相出料口，23为微反应器加热段夹套层的热媒出料口。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明提供了一种硝基苯的生产方法，在微反应器中进行硝化反应，用水稀释硝化反应所得混合物并离心分离获得粗品硝基苯，将粗品硝基苯进行离心洗涤，有效的提高了转化率、反应效率及产品纯度，具体过程如下：
1)调酸和调碱：
在搅拌下，将硫酸和硝酸按照一定比例从酸液缓存装置第一进料口(3)和酸液缓存装置第二进料口(4)加入酸液缓存装置(T2)；在搅拌下，将苯从苯缓存装置进料口(2)加入苯缓存装置(T1)。其中，所述硝酸质量含量优选25％～38％；所述硫酸质量含量优选52％～68％；所述苯与硝酸的物质的量比优选1:(1.05～1.1)。酸液缓存装置(T2)带有夹套，夹套中通冷凝水，以散去混合时产生的热。
在搅拌下，将纯碱和水按照一定比例从碱液缓存装置第一进料口(15)和碱液缓存装置第二进料口(16)加入碱液缓存装置(T5)。其中，所述碱液优选5～15％的纯碱溶液。碱缓存装置(T5)带有夹套，夹套中通冷凝水，以散去混合时产生的热。
2)硝化反应：
将苯缓存装置(T1)中的苯和酸液缓存装置(T2)中的混酸通过泵输送至微反应器的主进料口(6)进入微反应器进行硝化反应，此时，部分苯和部分硝酸完成了硝化；随后，硝化反应后的混合液继续与通过第一支进料口(7)进入微反应器的混酸进行完全硝化，得到完全硝化反应后的混合液。所述混合液主要成分为硝基苯及未反应完的少量硝酸及起催化作用的硫酸。
在本发明中，为保证上述反应温度的相对稳定，微反应器的加热段夹套层优选利用其热媒进料口(1)进入的一定温度的热水维持温度，热水从热媒出料口(23)流出。
在本发明中，加入微反应器的主进料口(6)和第一支进料口(7)的混酸可分2～3次加入微反应器；按照总计入量计算，分2次加入时，先后加入比例优选优选(55～68)wt％:(45～32)wt％，合计加入量为100wt％；分3次加入时，先后加入比例优选(45～52)wt％:(33～40)wt％:(8～22)wt％，合计加入量为100wt％。
在本发明中，进行硝化反应时的温度优选控制40～48℃，进行硝化反应时的压力优选控制控制在0.9～1.4MPa。
3)稀释：
为减少硝基苯在硫酸中的溶解，在硝化反应后，继续在微反应器中加入水，对混合液中的硫酸进行稀释。将酸稀释液缓存装置(T3)中的水通过泵输送至微反应器的第二支进料口(8)进入微反应器，在微反应器内与完全硝化反应后的混合液进行的混合，以稀释硫酸。
在本发明中，为保证上述分离温度的相对稳定，微反应器的加热段夹套层优选利用其热媒进料口(1)进入的一定温度的热水维持温度，热水从热媒出料口(23)流出。
在本发明中，稀释次数优选1～3次。稀释后的硫酸浓度优选60％～75％。
4)分离：
稀释后的混合液通过第一离心机进料口(9)进入离心机(C1)中进行离心分离，分离所得重组分的硫酸通过第一离心机水相出料口(11)输出；所得有机相(粗品硝基苯)通过第一离心机出料口输出，然后通过第二离心机第一进料口(10)进入第二离心机(C2)。
在本发明中，从第一离心机水相出料口(11)输出液优选60％～75％的硫酸。通过酸浓缩装置浓缩后，所述硫酸可作为浓酸继续循环利用。
为保证上述分离温度的相对稳定，离心机外夹套层利用一定温度的热水维持温度，以防止硝基苯的凝固。
5)洗涤：
将上述分离所得粗品硝基苯继续输入离心机中，进行离心洗涤。离心洗涤顺序为预洗、碱洗、终洗，具体为：
预洗：将上述输送至第二离心机第一进料口(10)的粗品硝基苯与通过泵输送至第二离心机第二进料口(12)的计量量的水，在离心机(C2)下端充 分混合，然后进行离心分离。分离所得水相从第二离心机水相出料口(14)输出；所得有机相(预洗后的硝基苯)输出后再通过第三离心机第一进料口(13)进入第三离心机(C3)。通过本次连续预洗，可洗涤掉粗品硝基苯中溶解的大部分酸。
碱洗：将上述输送至第三离心机第一进料口(13)的预洗后的硝基苯与通过泵输送至第三离心机第二进料口(17)的过量纯碱溶液，在离心机(C3)下端充分混合，后进行离心分离。分离所得水相从第三离心机水相出料口(19)输出；所得有机相(碱洗后的硝基苯)输出后再通过第四离心机第一进料口(18)进入第四离心机(C4)。通过本次连续碱洗，可洗涤掉硝基苯中全部酸。
终洗：将上述输送至第四离心机第一进料口(18)的碱洗后的硝基苯与通过泵输送至第四离心机第二进料口(20)的水，在离心机(C4)下端充分混合，后进行离心分离。分离所得水相从第四离心机有机相出料口(22)输出；所得有机相从第四离心机水相出料口(21)输出，得到纯度较高的硝基苯。通过本次连续终洗，可洗涤掉硝基苯中少量碱。
在本发明中，为保证上述预洗、碱洗和终洗温度的相对稳定，离心机外夹套层利用一定温度的热水维持温度，以防止硝基苯凝固。
在本发明中，上述预洗过程中，有机物与洗涤试剂水的质量比优选1:(0.11～0.28)；碱洗过程中，洗涤剂优选5～15％的纯碱溶液，有机物与洗涤试剂纯碱溶液的质量比优选1:(0.12～0.24)；终洗过程中，有机物与洗涤试剂水的质量比优选1:(0.11～0.26)。
本发明提供的硝基苯的生产方法具有如下优点：
1)苯转化率高：采用微反应器进行硝化反应，混酸分多次进料时，苯的转化率高；
2)反应和分离过程安全、速度快、效率高：在反应器和稀释器型式上，采用了微反应器，克服了传统釜式反应中存液量大而带来的较大安全问题，具有本质安全的优点。而且，物料在微反应器中停留时间约5～15秒，克服了传统釜式反应器中停留时间在30分钟以上的缺陷，具有反应速度明显快、反应效率高的特点；
3)洗涤纯化效率高：本采用离心机进行预洗、碱洗和终洗时，由于离心 机中存液量少，克服了传统塔式洗涤时存液量大危险性高的不足，且物料在离心机中停留时间约2～7秒，具有洗涤纯化速度快、效率高的优点。
为更清楚起见，下面通过以下实施例和对照例进行详细说明。
实施例1
在微通道反应器中进行硝化反应，其工艺流程如图1所示，具体过程为：
将苯和混酸通过泵输送至微通道反应器的主进料口(6)进入微通道反应器进行硝化反应，此时，部分苯和部分硝酸完成了硝化；随后，硝化反应后的混合液继续与通过第一支进料口(7)进入微通道反应器的混酸进行完全硝化，得到完全硝化反应后的混合液；前述混合液在第二支进料口(8)与酸稀释液缓存装置(T3)中输送的水进行混合，进入微通道反应器，以稀释硫酸；稀释后的混合液通过第一离心机进料口(9)进入离心机(C1)中进行离心分离；分离所得重组分的硫酸通过第一离心机水相出料口(11)输出；所得有机相(粗品硝基苯)通过第二离心机第一进料口(10)进入第二离心机(C2)，与通过泵输送至第二离心机第二进料口(12)的计量量的水，在离心机(C2)下端充分混合进行离心分离；分离所得水相从第二离心机水相出料口(14)输出，所得有机相通过第三离心机第一进料口(13)进入第三离心机(C3)，与通过泵输送至第三离心机第二进料口(17)的纯碱溶液，在离心机(C3)下端充分混合进行离心分离；分离所得水相从第三离心机水相出料口(19)输出，所得有机相通过第四离心机第一进料口(18)进入第四离心机(C4)，与通过泵输送至第四离心机第二进料口(20)的水，在离心机(C4)下端充分混合进行离心分离；分离所得水相从第四离心机有机相出料口(22)输出，所得有机相从第四离心机水相出料口(21)；
在本实施例中，混酸中硝酸质量含量25％，硫酸质量含量66％，所用苯与混酸中硝酸的物质的量比为1:1.05；所用混酸分2次加入微通道反应器，按照总计入量计算，先后2次加入混酸的比例为55wt％:45wt％；第二支进料口(8)的水，分3次进入微通道反应器，先后3次水用量比例为2:3:5；稀释后硫酸的质量百分浓度为60％；硝化反应温度控制在40℃，压力控制在0.9MPa；
在本实施例中，为保上述反应温度的相对稳定，微反应器的加热段夹套层优选利用其热媒进料口(1)进入的一定温度的热水维持温度，热水从热媒出 料口(23)流出；
在本实施例中，第一离心机水相出料口(11)输出的硫酸浓度为60％，通过酸浓缩装置浓缩后，作为浓酸继续循环利用；
在本实施例中，在第二离心机(C2)中，有机物与第二离心机第二进料口(12)水的质量比为1:0.11；在第三离心机(C3)中，第二进料口(17)纯碱溶液的浓度为5wt％；有机物与前述纯碱溶液的质量比为1:0.12；在第四离心机(C4)中，有机物与第四离心机第二进料口(20)水的质量比为1:0.11；
在本实施例中，为保证离心时温度的相对稳定，离心机外夹套层利用一定温度的热水维持温度，以防止硝基苯凝固。
实施例2
在微通道反应器中进行硝化反应，其工艺流程如图1所示，具体过程为：
将苯和混酸通过泵输送至微通道反应器的主进料口(6)进入微通道反应器进行硝化反应，此时，部分苯和部分硝酸完成了硝化；随后，硝化反应后的混合液继续与通过第一支进料口(7)进入微通道反应器的混酸进行完全硝化，得到完全硝化反应后的混合液；前述混合液在第二支进料口(8)与酸稀释液缓存装置(T3)中输送的水进行混合，进入微通道反应器，以稀释硫酸；稀释后的混合液通过第一离心机进料口(9)进入离心机(C1)中进行离心分离；分离所得重组分的硫酸通过第一离心机水相出料口(11)输出；所得有机相(粗品硝基苯)通过第二离心机第一进料口(10)进入第二离心机(C2)，与通过泵输送至第二离心机第二进料口(12)的计量量的水，在离心机(C2)下端充分混合进行离心分离；预洗分离所得水相从第二离心机水相出料口(14)输出；所得有机相(预洗后的硝基苯)通过第三离心机第一进料口(13)进入第三离心机(C3)，与通过泵输送至第三离心机第二进料口(17)的纯碱溶液，在离心机(C3)下端充分混合，离心分离；分离所得水相从第三离心机水相出料口(19)输出；所得有机相(碱洗后的硝基苯)通过第四离心机第一进料口(18)进入第四离心机(C4)，与通过泵输送至第四离心机第二进料口(20)的水，在离心机(C4)下端充分混合，离心分离；分离所得水相从第四离心机有机相出料口(22)输出；所得有机相从第四离心机水相出料口(21)；
在本实施例中，混酸中硝酸质量含量38％，硫酸质量含量52％，所用苯与 混酸中硝酸的物质的量比为1:1.1；所用混酸分2次加入微通道反应器，按照总计入量计算，先后2次加入混酸的比例为68wt％:32wt％；第二支进料口(8)的水，分2次进入微通道反应器，先后2次水用量比例为3:2；稀释后硫酸的质量百分浓度为75％；硝化反应温度控制在48℃，压力控制在1.4MPa；
在本实施例中，为保上述反应温度的相对稳定，微反应器的加热段夹套层优选利用其热媒进料口(1)进入的一定温度的热水维持温度，热水从热媒出料口(23)流出；
在本实施例中，第一离心机水相出料口(11)输出的硫酸浓度为75％，通过酸浓缩装置浓缩后，作为浓酸继续循环利用；
在本实施例中，在第二离心机(C2)中，有机物与第二离心机第二进料口(12)水的质量比为1:0.28；在第三离心机(C3)中，第二进料口(17)纯碱溶液的浓度为15wt％；有机物与前述纯碱溶液的质量比为1:0.24；在第四离心机(C4)中，有机物与第四离心机第二进料口(20)水的质量比为1:0.26；
在本实施例中，为保证离心时温度的相对稳定，离心机外夹套层利用一定温度的热水维持温度，以防止硝基苯凝固。
实施例3
在微通道反应器中进行硝化反应，其工艺流程如图1所示，具体过程为：
将苯和混酸通过泵输送至微通道反应器的主进料口(6)进入微通道反应器进行硝化反应，此时，部分苯和部分硝酸完成了硝化；随后，硝化反应后的混合液继续与通过第一支进料口(7)进入微通道反应器的混酸进行完全硝化，得到完全硝化反应后的混合液；前述混合液在第二支进料口(8)与酸稀释液缓存装置(T3)中输送的水进行混合，进入微通道反应器，以稀释硫酸；稀释后的混合液通过第一离心机进料口(9)进入离心机(C1)中进行离心分离；分离所得重组分的硫酸通过第一离心机水相出料口(11)输出；所得有机相(粗品硝基苯)通过第二离心机第一进料口(10)进入第二离心机(C2)，与通过泵输送至第二离心机第二进料口(12)的计量量的水，在离心机(C2)下端充分混合进行离心分离；预洗分离所得水相从第二离心机水相出料口(14)输出；所得有机相(预洗后的硝基苯)通过第三离心机第一进料口(13)进入第三离心机(C3)，与通过泵输送至第三离心机第二进料口(17)的纯碱溶液， 在离心机(C3)下端充分混合，离心分离；分离所得水相从第三离心机水相出料口(19)输出；所得有机相(碱洗后的硝基苯)通过第四离心机第一进料口(18)进入第四离心机(C4)，与通过泵输送至第四离心机第二进料口(20)的水，在离心机(C4)下端充分混合，离心分离；分离所得水相从第四离心机有机相出料口(22)输出；所得有机相从第四离心机水相出料口(21)；
在本实施例中，混酸中硝酸质量含量30％，硫酸质量含量59％，所用苯与混酸中硝酸的物质的量比为1:1.08；所用混酸分2次加入微通道反应器，按照总计入量计算，先后2次加入混酸的比例为70wt％:30wt％；第二支进料口(8)的水，1次性进入微通道反应器，稀释后硫酸的质量百分浓度为70％；硝化反应温度控制在45℃，压力控制在1.0MPa；
在本实施例中，为保上述反应温度的相对稳定，微反应器的加热段夹套层优选利用其热媒进料口(1)进入的一定温度的热水维持温度，热水从热媒出料口(23)流出；
在本实施例中，第一离心机水相出料口(11)输出的硫酸浓度为70％，通过酸浓缩装置浓缩后，作为浓酸继续循环利用；
在本实施例中，在第二离心机(C2)中，有机物与第二离心机第二进料口(12)水的质量比为1:0.20；在第三离心机(C3)中，第二进料口(17)纯碱溶液的浓度为10wt％；有机物与前述纯碱溶液的质量比为1:0.18；在第四离心机(C4)中，有机物与第四离心机第二进料口(20)水的质量比为1:0.19；
在本实施例中，为保证离心时温度的相对稳定，离心机外夹套层利用一定温度的热水维持温度，以防止硝基苯凝固。
实施例4
在微通道反应器中进行硝化反应，其工艺流程如图1所示，具体过程为：
将苯和混酸通过泵输送至微通道反应器的主进料口(6)进入微通道反应器进行硝化反应，此时，部分苯和部分硝酸完成了硝化；随后，硝化反应后的混合液继续与通过第一支进料口(7)进入微通道反应器的混酸进行完全硝化，得到完全硝化反应后的混合液；前述混合液在第二支进料口(8)与酸稀释液缓存装置(T3)中输送的水进行混合，进入微通道反应器，以稀释硫酸；稀释后的混合液通过第一离心机进料口(9)进入离心机(C1)中进行离心分离； 分离所得重组分的硫酸通过第一离心机水相出料口(11)输出；所得有机相(粗品硝基苯)通过第二离心机第一进料口(10)进入第二离心机(C2)，与通过泵输送至第二离心机第二进料口(12)的计量量的水，在离心机(C2)下端充分混合进行离心分离；预洗分离所得水相从第二离心机水相出料口(14)输出；所得有机相(预洗后的硝基苯)通过第三离心机第一进料口(13)进入第三离心机(C3)，与通过泵输送至第三离心机第二进料口(17)的纯碱溶液，在离心机(C3)下端充分混合，离心分离；分离所得水相从第三离心机水相出料口(19)输出；所得有机相(碱洗后的硝基苯)通过第四离心机第一进料口(18)进入第四离心机(C4)，与通过泵输送至第四离心机第二进料口(20)的水，在离心机(C4)下端充分混合，离心分离；分离所得水相从第四离心机有机相出料口(22)输出；所得有机相从第四离心机水相出料口(21)；
在本实施例中，混酸中硝酸质量含量31％，硫酸质量含量59％，所用苯与混酸中硝酸的物质的量比为1:1.08；所用混酸分3次加入微通道反应器，按照总计入量计算，先后2次加入混酸的比例为45wt％:42wt％:13wt％；第二支进料口(8)的水，分2次进入微通道反应器，先后2次水用量比例为2:3；稀释后硫酸的质量百分浓度为70％；硝化反应温度控制在41℃，压力控制在1.1MPa；
在本实施例中，为保上述反应温度的相对稳定，微反应器的加热段夹套层优选利用其热媒进料口(1)进入的一定温度的热水维持温度，热水从热媒出料口(23)流出；
在本实施例中，第一离心机水相出料口(11)输出的硫酸浓度为70％，通过酸浓缩装置浓缩后，作为浓酸继续循环利用；
在本实施例中，在第二离心机(C2)中，有机物与第二离心机第二进料口(12)水的质量比为1:0.19；在第三离心机(C3)中，第二进料口(17)纯碱溶液的浓度为10wt％；有机物与前述纯碱溶液的质量比为1:0.17；在第四离心机(C4)中，有机物与第四离心机第二进料口(20)水的质量比为1:0.18；
在本实施例中，为保证离心时温度的相对稳定，离心机外夹套层利用一定温度的热水维持温度，以防止硝基苯凝固。
实施例5
同实施例1，不同之处在于反应器为管式反应器。
实施例6
同实施例2，不同之处在于反应器为管式反应器。
实施例7
同实施例3，不同之处在于反应器为管式反应器。
实施例8
同实施例4，不同之处在于反应器为管式反应器。
对照例1
采用计量泵，向连续串联的3级反应釜第一级釜中加入硝基苯，向第三级釜中加入硝硫混酸，为维持反应稳定、防止反应过于剧烈，硝基苯和混酸采用逆向流动。前述反应完成后，将分离出的下层酸进入稀释塔中进行1次稀释并分液，下层硫酸浓度保持在60％。采用3塔串联，将上述分离出的上层有机物依次用水、纯碱液和水进行预洗、碱洗和终洗，洗涤时有机物与洗涤剂流向为逆流，即水相洗涤剂从塔下部进入，从上部留出，有机相从下层流出。
上述苯与混酸中硝酸的物质的量比为1:1.05，混酸中硝酸质量含量25％，硫酸质量含量66％，反应温度为40℃，压力为常压。
上述预洗、碱洗和终洗的洗涤液分别为水、5％的纯碱溶液和水，预洗、碱洗和终洗中，有机物与洗涤试剂的质量比分别为1:0.11、1:0.12、1:0.11。
对照例2
采用计量泵，向连续串联的3级反应釜第一级釜中加入硝基苯，向第三级釜中加入硝硫混酸，为防止反应过于剧烈，硝基苯和混酸保持逆向流动。前述反应完成后，将分离出的下层酸进入稀释塔中进行1次稀释并分液，下层硫酸浓度保持在75％。采用3塔串联，将上述分离出的上层有机物依次用水、纯碱液和水进行预洗、碱洗和终洗，洗涤时有机物与洗涤剂流向为逆流，即水相洗涤剂从塔下部进入，从上部留出，有机相从下层流出。
上述苯与混酸中硝酸的物质的量比为1:1.08，配制的混酸中硝酸质量含量为38％，硫酸质量含量为52％，反应温度为48℃，压力为常压。
上述预洗、碱洗和终洗的洗涤液分别为水、10％的纯碱溶液和水，预洗、碱洗和终洗中，有机物与洗涤试剂的质量比分别为1:0.28、1:0.24、1:0.26。
对照例3
采用计量泵，向连续串联的3级反应釜第一级釜中加入硝基苯，向第三级釜中加入硝硫混酸，为防止反应过于剧烈，硝基苯和混酸保持逆向流动，反应温度为45℃，压力为常压。前述反应完成后，将分离出的下层酸进入稀释塔中进行1次稀释并分液，下层硫酸浓度保持在70％。采用3塔串联，将上述分离出的上层有机物依次用水、纯碱液和水进行预洗、碱洗和终洗，洗涤时有机物与洗涤剂流向为逆流，即水相洗涤剂从塔下部进入，从上部留出，有机相从下层流出。
上述苯与混酸中硝酸的物质的量比为1:1.1，所配制的混酸中硝酸质量含量24％，硫酸质量含量69％。
上述预洗、碱洗和终洗的洗涤液分别为水、15％的纯碱溶液和水，预洗、碱洗和终洗中，有机物与洗涤试剂的质量比分别为1:0.20、1:0.18、1:0.21。
实验结果
对实施例1～8的实验结果与对照例1～3的实验结果进行汇总，详见表1：
表1硝基苯生产实验结果
Figure PCTCN2022137440-appb-000001
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (10)

  1. 一种硝基苯的生产方法，其特征在于，包括以下步骤：
    将苯与酸液混合后送入微反应器的主进料口，进行部分硝化反应；随后与通过第一支进料口加入到微反应器内的酸液混合，进行完全硝化反应；接着与通过第二支进料口加入到微反应器内的水混合进行稀释；之后从出料口排出微反应器；
    从所述出料口排出微反应器的产物进入第一离心机进行离心分离，所得有机相依次通过第二、第三和第四离心机进行离心洗涤，得到硝基苯；
    所述离心洗涤的步骤具体为：将所述第一离心机中离心所得有机相送入第二离心机的第一进料口，与通过第二离心机的第二进料口加入的水混合后进行离心预洗；离心预洗所得有机相送入第三离心机的第一进料口，与通过第三离心机的第二进料口加入的碱液混合后进行离心碱洗；离心碱洗所得有机相送入第四离心机的第一进料口，与通过第四离心机的第二进料口加入的水混合后进行离心终洗，所得有机相从第四离心机的有机相出料口排出离心机；所述离心洗涤的过程中，水相均从离心机的水相出料口排出离心机。
  2. 根据权利要求1所述的生产方法，其特征在于，所述微反应器为微通道反应器或管式反应器。
  3. 根据权利要求1所述的生产方法，其特征在于，进行所述部分硝化反应和完全硝化反应所用的酸液为含有硝酸与硫酸的混合酸液，其中硝酸的质量含量25～38％，硫酸的质量含量52～66％。
  4. 根据权利要求1所述的生产方法，其特征在于，所述苯与反应用酸液中硝酸的物质的量比为1：(1.05～1.1)。
  5. 根据权利要求1所述的生产方法，其特征在于，进行所述部分硝化反应和完全硝化反应所用的酸液分2～3次加入微反应器。
  6. 根据权利要求5所述的生产方法，其特征在于，按照所用酸液的总加入量计算，分2次加入时，先后加入比例为(55～68)wt％：(45～32)wt％，合计加入量为100wt％；分3次加入时，先后加入比例为(45～52)wt％：(33～40)wt％：(8～22)wt％，合计加入量为100wt％。
  7. 根据权利要求1所述的生产方法，其特征在于，所述部分硝化反应和和完全硝化反应的温度独立地选择40～48℃，所述部分硝化反应和和完全硝化反应的压力独立地选择0.9～1.4MPa。
  8. 根据权利要求3所述的生产方法，其特征在于，进行所述稀释后，体系中硫酸的质量百分浓度为60～75％。
  9. 根据权利要求1所述的生产方法，其特征在于，所述碱液为5～15wt％的纯碱溶液。
  10. 根据权利要求1所述的生产方法，其特征在于，所述离心预洗过程中，有机相与水的质量比为1：(0.11～0.28)；所述离心碱洗过程中，有机相与碱液的质量比为1：(0.12～0.24)；所述离心终洗过程中，有机相与水的质量比为1：(0.11～0.26)。
PCT/CN2022/137440 2022-06-28 2022-12-08 一种硝基苯的生产方法 WO2024001054A1 (zh)

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