Nitration reaction post-treatment device

Abstract

The utility model provides a nitration reaction post-treatment device. The nitration reaction post-treatment device comprises a nitration kettle, a separation tank, a distillation kettle and an acid storage tank which are sequentially connected in series, the separation tank is also sequentially connected with an alkali washing device and a nitration product storage tank; the alkali washing device is further connected with an alkali liquor storage tank through a metering pump, and the alkali washing device is further connected with a waste alkali liquor tank to form a loop; the distillation kettle is also connected with a nitric acid collecting tank. According to the device disclosed by the invention, by virtue of cooperative use of the equipment, while a nitration product is subjected to alkali washing post-treatment, reacted waste acid is distilled to realize stage treatment of the waste acid, so that the recycling value of the waste acid is improved, and the defects of low recycling value of the waste acid, low cost and the like in the existing nitration post-treatment process are overcome. And resources are wasted due to the fact that the materials are difficult to fully utilize.

Description

Technical Field

[0001] The present application relates to the technical field of organic synthesis, and in particular to a post-processing device for nitration reaction. Background Art

[0002] 2,4-Difluoronitrobenzene is an important pesticide and pharmaceutical intermediate. It can be used to synthesize 2,4-difluoro-5-nitrobenzenesulfonic acid, masferin, and resin-bound 2-arylaminobenzimidazoles. Furthermore, 2,4-difluoronitrobenzene is a reactant in the preparation of 4-thiazolidinone derivatives, which are used as antibacterial agents. 2,4-Difluoronitrobenzene can be hydrogenated to produce 2,4-difluoroaniline, which is also an important pharmaceutical and pesticide intermediate.

[0003] The mainstream synthesis route for 2,4-difluoronitrobenzene uses m-dichlorobenzene as a raw material through nitration and fluorination processes. The nitration of m-dichlorobenzene is completed in a mixed acid system (a mixture of concentrated sulfuric acid and concentrated nitric acid). The m-dichlorobenzene nitration product obtained during the nitration process requires deacidification and other treatments before entering the next reaction. Because mixed acids are used in the nitration process, a large amount of waste acid is generated after the reaction. This waste acid is large in volume and contains organic matter, making it difficult to reuse. The conventional practice is to use it to neutralize the alkaline wastewater within the factory, but this method only consumes a small amount of waste acid, which makes the reuse value of the large amount of waste acid low, difficult to fully utilize, and leads to waste of resources. Utility Model Content

[0004] The present application provides a nitration reaction post-treatment device to solve the problem in the above-mentioned existing nitration reaction post-treatment process that the waste acid has low recycling value and is difficult to be fully utilized, resulting in waste of resources.

[0005] The present application provides a nitration reaction post-processing device, comprising a nitration kettle, a separation tank, a distillation kettle and an acid storage tank connected in series;

[0006] The separation tank is also connected to the alkali washing device and the nitration product storage tank in sequence;

[0007] The alkali washing device is also connected to the alkali liquid storage tank through a metering pump, and the alkali washing device is also connected to the waste alkali liquid tank to form a loop;

[0008] The distillation kettle is also connected to the nitric acid collection tank.

[0009] Optionally, the acid storage tank is also connected to the concentration tower;

[0010] The concentration tower is respectively connected to the vacuum unit, the organic matter collection tank, the sulfuric acid storage tank and the kettle residue treatment device.

[0011] Optionally, the waste alkali liquid tank is also connected to the neutralization tank;

[0012] The neutralization tank is also connected to the sulfuric acid storage tank.

[0013] Optionally, the neutralization tank is also connected in series with the multiple-effect evaporator and the crystallization kettle.

[0014] Optionally, a thickener is further provided between the multiple-effect evaporator and the crystallization kettle.

[0015] Optionally, a condenser is further provided between the concentration tower and the vacuum unit.

[0016] Optionally, the alkali washing device includes a plurality of centrifugal extractors connected in series.

[0017] The nitration reaction post-processing device provided by the present application is provided with a separation tank to separate and separate the reaction product and the waste acid, and the waste acid obtained after the separation is transferred to a distillation kettle for distillation, the nitric acid and sulfuric acid in the waste acid are separated, and the nitric acid in the waste acid is separated and collected in a nitric acid collecting tank, so as to realize the classification recovery of the waste acid and improve the reuse value of the waste acid; and at the same time, an alkali washing device is provided to alkali wash the reaction product obtained by separation in the separation tank, remove the mixed acid in the reaction product, collect the nitration product after alkali washing in a nitration product storage tank for subsequent processing, and at the same time, transfer the waste alkali liquid obtained after alkali washing to a waste alkali liquid tank and put it back into the alkali washing device for reuse. The device of the present application is used in conjunction with the above-mentioned equipment to carry out alkali washing post-processing of the nitration product while distilling the waste acid after the reaction to realize the graded treatment of the waste acid, thereby improving the reuse value of the waste acid and overcoming the problem that the waste acid recovery value is low and it is difficult to be fully utilized in the existing nitration reaction post-processing process, resulting in waste of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] Figure 1 A schematic diagram of a nitration reaction post-treatment device provided in one embodiment of the present application;

[0020] Figure 2 A schematic diagram of a nitration reaction post-treatment device provided in another embodiment of the present application;

[0021] Figure 3 A schematic diagram of a nitration reaction post-treatment device provided in another embodiment of the present application;

[0022] Figure 4 A schematic diagram of a nitration reaction post-treatment device provided in yet another embodiment of the present application;

[0023] Figure 5 A schematic diagram of a nitration reaction post-treatment device provided in one embodiment of the present application;

[0024] Figure 6 A schematic diagram of a nitration reaction post-treatment device provided in one embodiment of the present application;

[0025] Figure 7 A schematic diagram of an alkaline washing device provided in one embodiment of the present application.

[0026] Description of reference numerals:

[0027] 1. Nitration kettle; 2. Separation tank; 3. Distillation kettle; 4. Acid storage tank; 5. Alkali washing device; 6. Nitration product storage tank; 7. Concentration tower; 31. Nitric acid collection tank; 51. Centrifugal extractor; 61. Metering pump; 62. Alkali liquid storage tank; 63. Waste alkali liquid tank; 64. Neutralization tank; 65. Multi-effect evaporator; 66. Crystallization kettle; 67. Thickener; 71. Vacuum unit; 72. Organic matter collection tank; 73. Sulfuric acid storage tank; 74. Kettle residue treatment device; 75. Condenser. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application are clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts also fall within the scope of protection of this application.

[0029] like Figure 1 As shown, the present application provides a nitration reaction post-processing device, comprising a nitration kettle 1, a separation tank 2, a distillation kettle 3 and an acid storage tank 4 connected in series;

[0030] The separation tank 2 is also connected to the alkaline washing device 5 and the nitration product storage tank 6 in sequence;

[0031] The alkali washing device 5 is also connected to the alkali liquid storage tank 62 through the metering pump 61, and the alkali washing device 5 is also connected to the waste alkali liquid tank 63 to form a loop;

[0032] The distillation kettle 3 is also connected to the nitric acid collecting tank 31.

[0033] During use, the reaction substrate (meta-dichlorobenzene in this application) reacts with the mixed acid in the nitration kettle 1 to produce a nitration product. After the reaction is completed, the reaction liquid is transferred to the separation tank 2. Since the reaction product and the mixed acid are immiscible, they will separate into layers after standing in the separation tank 2. The organic phase after separation (i.e., the reaction product) is transferred to the alkaline washing device 5 for alkaline washing and acid removal; the acid phase (containing organic substances such as sulfuric acid, nitric acid, meta-dichlorobenzene and its nitration product) is transferred to the distillation kettle 3 for treatment.

[0034] Enter into the acid phase in the still kettle 3, in still kettle 3, be heated, the nitric acid in the acid phase can be steamed (83 ℃ of boiling points of nitric acid, 122 ℃ of boiling points of nitric acid-water azeotrope, lower than 338 ℃ of boiling points of sulfuric acid and meta-dichlorobenzene and nitrated product thereof>170 ℃ boiling point, therefore controlled temperature has only nitric acid and water to be steamed lower than 130 ℃ of these processes in the heat-processed), because nitric acid has part to decompose and produce nitrogen dioxide and oxygen and water in the heat-processed, but the product of nitric acid decomposition can be dissolved in the nitric acid again, therefore can be together cooled off and be collected in the nitric acid holding tank 31 with nitric acid, now, can bubbling air in nitric acid holding tank 31 to promote that nitrogen dioxide is changed into nitric acid.Because the boiling point of sulfuric acid and meta-dichlorobenzene and nitrated product thereof is higher than nitric acid, therefore remaining after still kettle 3 distillation is sulfuric acid, water and meta-dichlorobenzene and nitrated product thereof, these mixtures are transferred in the acid storage tank 4 for temporary storage.

[0035] The organic phase separated in the separation tank 2, i.e., the reaction product, is transferred to the alkali washing device 5, where it is mixed with the alkali solution in the alkali solution storage tank 62 drawn by the metering pump 61 for alkali washing. The organic phase after alkali washing, i.e., the treated reaction product, is temporarily stored in the nitration product storage tank 6 for subsequent processing or reaction. The waste alkali solution after washing is stored in the waste alkali solution tank 63. Since a slight excess of alkali is used in the washing process, some of the waste alkali solution can be recycled to the alkali washing device 5 for reuse, depending on the specific situation.

[0036] The nitration reaction post-treatment device provided by the present application is provided with a separation tank 2 to separate and separate the reaction product and waste acid, and the waste acid obtained after the separation is transferred to a distillation kettle 3 for distillation, separating the nitric acid and sulfuric acid in the waste acid, and collecting the nitric acid in the waste acid in a nitric acid collection tank 31, thereby realizing the classified recovery of the waste acid and improving the reuse value of the waste acid; and at the same time, an alkali washing device 5 is provided to alkali wash the reaction product separated by the separation tank 2 to remove the mixed acid in the reaction product, and collect the nitration product after alkali washing in a nitration product storage tank 6 for subsequent treatment. At the same time, the waste alkali liquid obtained after alkali washing is transferred to a waste alkali liquid tank 63 and returned to the alkali washing device 5 for reuse. The device of the present application uses the above-mentioned equipment in conjunction with the use of the above-mentioned equipment to carry out alkali washing post-treatment of the nitration product while distilling the waste acid after the reaction to achieve graded treatment of the waste acid, thereby improving the reuse value of the waste acid, and overcoming the problem that the waste acid recovery value is low and it is difficult to be fully utilized in the existing nitration reaction post-treatment process, resulting in waste of resources.

[0037] like Figure 2 As shown, optionally, the acid storage tank 4 is also connected to the concentration tower 7;

[0038] The concentration tower 7 is connected to a vacuum unit 71 , an organic matter collecting tank 72 , a sulfuric acid storage tank 73 and a kettle residue treatment device 74 , respectively.

[0039] In the present application, during use, the acidic mixture of sulfuric acid and organic matter temporarily stored in the acid storage tank 4 is transferred to the concentration tower 7, which is also a distillation tower. The tower top is evacuated and depressurized by a vacuum unit 71 to reduce the boiling point of the materials in the tower. The bottom of the tower heats the acidic mixture. Since the boiling points of organic matter and water are much lower than that of sulfuric acid, part of the water (part of the water and sulfuric acid will form an azeotrope with a temperature of nearly 338°C) and organic matter will be evaporated first during the distillation and concentration process and collected in the organic matter collection tank 72 for subsequent centralized treatment. The bottom residue after distillation is mainly sulfuric acid (at this time, its concentration is about 75% to 83%) and a small amount of high-boiling-point polymers produced during the reaction process. The bottom residue after distillation is separated, and the separated sulfuric acid is transferred to the sulfuric acid storage tank 73 for recovery and standby use, while the high-boiling-point polymer bottom residue is transferred to the bottom residue treatment device 74 for treatment (such as incineration in an incinerator for harmless operation).

[0040] like Figure 3 As shown, optionally, the waste alkali liquid tank 63 is also connected to the neutralization tank 64;

[0041] The neutralization tank 64 is also connected to the sulfuric acid storage tank 73 .

[0042] In the present application, the alkaline waste liquid (containing nitrates, sulfates, alkalis and a small amount of organic matter produced after neutralization) stored in the waste alkali liquid tank 63 is transferred to the neutralization tank 64, and at the same time, the sulfuric acid stored in the sulfuric acid storage tank 73 is transferred to the neutralization tank 64 to neutralize the alkaline waste liquid to a weak acidity (pH = 6.5 ~ 7). At this time, the alkali in the alkaline waste liquid is completely converted into the corresponding salt.

[0043] like Figure 4 As shown, optionally, the neutralization tank 64 is further connected in series with the multi-effect evaporator 65 and the crystallization kettle 66 in sequence.

[0044] The neutralized alkaline waste liquid is transferred to the multi-effect evaporator 65 for evaporation and concentration, and the concentrated waste liquid is injected into the crystallization kettle 66 for crystallization and recrystallization to obtain high-purity salt.

[0045] like Figure 5 As shown, optionally, a thickener 67 is further provided between the multi-effect evaporator 65 and the crystallization kettle 66 .

[0046] In this application, a thickener, also known as a thickener or concentrator, is used to concentrate solid particles in a suspension. In this application, the waste liquid concentrated by the multi-effect evaporator 65 is injected into the thickener 67 to concentrate the precipitated salt (where the salt and mother liquor are separated). The concentrated salt is then transferred to the crystallizer 66 for recrystallization to obtain high-purity salt.

[0047] like Figure 6 As shown, optionally, a condenser 75 is further provided between the concentration tower 7 and the vacuum unit 71 .

[0048] In the present application, during the process of vacuuming the concentration tower 7 by the vacuum unit 71, some low-boiling-point materials such as water and organic matter will be extracted from the top of the tower. In order to prevent these materials from entering the equipment of the vacuum unit 71 and causing damage to the equipment, the condenser 75 arranged between the concentration tower 7 and the vacuum unit 71 can condense these extracted materials to prevent them from being drawn into the vacuum unit 71.

[0049] like Figure 7 As shown, optionally, the alkali washing device 5 includes a plurality of centrifugal extractors 51 connected in series.

[0050] In the present application, the centrifugal extractor 51 is a fast, efficient extraction device that utilizes centrifugal force to increase the density difference between the two liquids, thereby enhancing phase separation. It has a high mass transfer efficiency, can handle extraction systems with very small density differences, and can operate within a wide range of phase ratios and densities. The two phases spend very little time within the extractor, reaching extraction equilibrium in just a few seconds. It has the advantages of large throughput, high efficiency, a large number of theoretical stages, a compact structure, and a small footprint. Using multiple centrifugal extractors 51 in series can improve the efficiency of washing the reaction products.

[0051] The present application provides a nitration reaction post-processing device, the working process of which is as follows:

[0052] During use, the reaction substrate (meta-dichlorobenzene in this application) reacts with the mixed acid in the nitration kettle 1 to produce a nitration product. After the reaction is completed, the reaction liquid is transferred to the separation tank 2. Since the reaction product and the mixed acid are immiscible, they will separate into layers after standing in the separation tank 2. The organic phase after separation (i.e., the reaction product) is transferred to the alkaline washing device 5 for alkaline washing and acid removal; the acid phase (containing organic substances such as sulfuric acid, nitric acid, meta-dichlorobenzene and its nitration product) is transferred to the distillation kettle 3 for treatment.

[0053] Enter into the acid phase in the still kettle 3, in still kettle 3, be heated, the nitric acid in the acid phase can be steamed (83 ℃ of boiling points of nitric acid, 122 ℃ of boiling points of nitric acid-water azeotrope, lower than 338 ℃ of sulfuric acid boiling points and meta-dichlorobenzene and nitrated product thereof>170 ℃ boiling point, therefore control temperature is lower than 130 ℃ in the heating process, this process only has nitric acid and water to be steamed), because nitric acid has part to decompose and produces nitrogen dioxide and oxygen and water in the heating process, but the product of nitric acid decomposition can be dissolved in the nitric acid again, therefore can be together cooled off and be collected in the nitric acid holding tank 31 with nitric acid, now, can bubbling air in nitric acid holding tank 31 to promote that nitrogen dioxide is changed into nitric acid.Because the boiling point of sulfuric acid and meta-dichlorobenzene and nitrated product thereof is higher than nitric acid, therefore remaining after still kettle 3 distillation is sulfuric acid, water and meta-dichlorobenzene and nitrated product thereof, these mixtures are transferred in the acid storage tank 4 temporary storage.

[0054] The acidic mixture of sulfuric acid and organic matter temporarily stored in the acid storage tank 4 is transferred to the concentration tower 7, also known as the distillation tower. A vacuum unit 71 is used at the top of the tower to evacuate and reduce the pressure inside the tower to lower the boiling point of the materials inside. The bottom of the tower heats the acidic mixture. Because the boiling points of organic matter and water are much lower than that of sulfuric acid, some water (some water and sulfuric acid will form an azeotrope due to hydrogen bonds, and the temperature is close to 338°C and will not be distilled off) and organic matter will be distilled off first during the distillation and concentration process. The bottom residue after distillation is mainly sulfuric acid (at this time, its concentration is approximately 75% to 83%) and a small amount of high-boiling-point polymers produced during the reaction. The bottom residue after distillation is separated, and the separated sulfuric acid is transferred to the sulfuric acid storage tank 73 for recovery and use. The high-boiling-point polymer bottom residue is transferred to the bottom residue treatment device 74 for treatment (such as incineration in an incinerator for harmless treatment). During the process of vacuuming the concentration tower 7 by the vacuum unit 71, some low-boiling-point materials such as water and organic matter will be extracted from the top of the tower. In order to prevent these materials from entering the equipment of the vacuum unit 71 and causing damage to the equipment, the condenser 75 arranged between the concentration tower 7 and the vacuum unit 71 can condense these extracted materials to prevent them from being drawn into the vacuum unit 71.

[0055] The organic phase separated in the separation tank 2, i.e., the reaction product, is transferred to the alkali washing device 5 and mixed with the alkali liquid in the alkali liquid storage tank 62 drawn by the metering pump 61 for alkali washing. The alkali washing device 5 comprises multiple centrifugal extractors 51 connected in series to improve the efficiency of alkali washing. The organic phase after alkali washing, i.e., the treated reaction product, is temporarily stored in the nitration product storage tank 6 for subsequent processing or reaction. The waste alkali liquid after washing is stored in the waste alkali liquid tank 63. Since a slight excess of alkali is used in the washing process, some of the waste alkali liquid can be recycled to the alkali washing device 5 for reuse, depending on the specific situation.

[0056] The alkaline waste liquid (containing nitrates, sulfates, alkali, and a small amount of organic matter produced after neutralization) stored in the waste alkali liquid tank 63 is transferred to the neutralization tank 64. Simultaneously, the sulfuric acid stored in the sulfuric acid storage tank 73 is transferred to the neutralization tank 64 to neutralize the alkaline waste liquid to a weak acidity (pH = 6.5-7). At this point, the alkali in the alkaline waste liquid is completely converted into the corresponding salt. The neutralized alkaline waste liquid is then transferred to the multi-effect evaporator 65 for evaporation and concentration. The concentrated waste liquid is then injected into the thickener 67 to concentrate the precipitated salt (where the salt and mother liquor are separated). The concentrated salt is then transferred to the crystallizer 66 for recrystallization to obtain high-purity salt. This completes the post-treatment process of the nitration product.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A nitration reaction post-treatment device, characterized in that: It comprises a nitrification kettle (1), a separation tank (2), a distillation kettle (3) and an acid storage tank (4) connected in series; The separation tank (2) is also connected to the alkali washing device (5) and the nitration product storage tank (6) in sequence; The alkali washing device (5) is also connected to the alkali liquid storage tank (62) via a metering pump (61), and the alkali washing device (5) is also connected to the waste alkali liquid tank (63) to form a loop; The distillation kettle (3) is also connected to the nitric acid collection tank (31); The acid storage tank (4) is also connected to the concentration tower (7); The concentration tower (7) is respectively connected to the vacuum unit (71), the organic matter collection tank (72), the sulfuric acid storage tank (73) and the kettle residue treatment device (74); The waste alkali liquid tank (63) is also connected to the neutralization tank (64); The neutralization tank (64) is also connected to the sulfuric acid storage tank (73).

2. The nitration reaction post-processing device according to claim 1, characterized in that: The neutralization tank (64) is also connected in series with the multi-effect evaporator (65) and the crystallization kettle (66).

3. The nitration reaction post-processing device according to claim 2, characterized in that: A thickener (67) is further provided between the multi-effect evaporator (65) and the crystallization kettle (66).

4. The nitration reaction post-processing device according to claim 1, characterized in that: A condenser (75) is further provided between the concentration tower (7) and the vacuum unit (71).

5. The nitration reaction post-treatment device according to any one of claims 1 to 4, characterized in that: The alkaline washing device (5) comprises a plurality of centrifugal extractors (51) connected in series.

Images