Method and apparatus system for continuous production of nitrochlorobenzene and use thereof

Abstract

The present application relates to the technical field of chemical production, and discloses a method and device system for continuously producing nitrochlorobenzene and application thereof. In the method, mixing of reaction raw materials and reaction are completed in steps, so that the defect of too severe heat release, too high temperature, side reaction and safety problem caused by direct reaction is avoided. Meanwhile, by controlling the volume flow ratio of nitric acid and chlorobenzene feed, the raw material conversion rate and the yield of the target product are improved, and the proportion of p-nitrochlorobenzene in the product is also increased, so that the economic benefit is improved. In addition, the method provided by the present application does not need concentrated sulfuric acid as a catalyst, so that the problem of difficult treatment of waste sulfuric acid is solved, and the environmental protection of nitrochlorobenzene production is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical production, in particular to a method and device system for continuous production of nitrochlorobenzene and application thereof. BACKGROUND

[0002] Nitrochlorobenzene is an important fine chemical intermediate, which is involved in many fields such as medicine, pesticide, dye, and chemical industry. The current production method of nitrochlorobenzene mainly adopts mixed acid nitration method. The production process includes traditional nitration process and adiabatic nitration process. The traditional nitration process mainly uses a nitration reactor with strong stirring and cooling device. Chlorobenzene and mixed acid (usually composed of sulfuric acid, nitric acid and water, with high acid concentration) are introduced into the reactor in a certain proportion for nitration reaction. The heat is removed through continuous stirring and cooling device to control the temperature of the feed. Then the reaction product is sequentially separated, washed with alkali, washed with water, crystallized, dried, etc. to obtain nitrochlorobenzene product. The traditional nitration process mainly adopts batch production mode, which has slow reaction speed, long cycle, low efficiency, unstable reaction conditions, many side reactions, poor product quality, large amount of mixed acid, and low safety and environmental protection.

[0003] The adiabatic nitration process is a new type of nitration technology developed in the 1970s abroad. The process mainly uses micro-channel reaction technology to precisely control the reaction temperature, breaks through the traditional concept that nitration reaction must be operated at low temperature and constant temperature, eliminates the cooling device, saves a large amount of cooling water for removing reaction heat, and fully utilizes the mixing heat and reaction heat to improve the reaction speed. Therefore, the material residence time is short, the side reaction is less, and the dilute acid after reaction can be recycled. However, although the micro-channel reaction ensures the safety of the reaction process, the storage and separation of the material in the subsequent process still have the problems of large storage capacity and uncontrollable by-products and temperature. In addition, the small pipe diameter of the micro-channel reaction equipment is easy to block, which causes new problems of production efficiency and safety. In addition, the micro-channel production technology actually uses mixed acid production process, which still cannot avoid the problems of difficult waste acid discharge and treatment, high cost, and poor safety. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned problems in the prior art, and to provide a method and device system for continuous production of nitrochlorobenzene and application thereof. The method provided by the present application can realize the direct nitration of chlorobenzene, avoid the addition of sulfuric acid, and solve the environmental protection problems and production safety problems caused by the discharge and treatment of mixed acid in the production of nitrochlorobenzene. In addition, the method can also realize the continuous and automatic production of nitrochlorobenzene, and reduce the labor cost of production.

[0005] In order to achieve the above object, the present application provides a method for producing nitrochlorobenzene, characterized in that the method comprises introducing raw material A and raw material B into a mixing device for mixing, and then introducing the obtained raw material mixture into a reaction device for nitration reaction to obtain a reaction product, wherein raw material A and raw material B are one of nitric acid and chlorobenzene respectively, and the raw material mixture comprises nitric acid, chlorobenzene and nitrochlorobenzene, and the temperature of the material in the mixing device is not more than 60℃.

[0006] The second aspect of the present application provides a device system for continuously producing nitrochlorobenzene, characterized in that the device system comprises a mixing device and a reaction device, wherein the mixing device comprises a feeding pipe A and a feeding pipe B for introducing raw material A and raw material B respectively, and the raw material mixture is obtained, and then the raw material mixture is introduced into the reaction device for nitration reaction to obtain a reaction product.

[0007] The third aspect of the present application provides the application of the above-mentioned method and device system in the industrial production of nitrochlorobenzene

[0008] Through the above technical solution, the present application can achieve the following beneficial effects:

[0009] (1) In the device system provided by the present application, the feeding pipe A is connected with the feeding pipe B containing multiple branches, so that the multiple feeding of nitric acid / chlorobenzene is realized, and the multiple mixing of chlorobenzene and nitric acid in the mixing device is realized, compared with one-time mixing, the heat release after the contact of raw materials is reduced, the production safety is improved, and the occurrence of side reactions is reduced, and the product quality is improved.

[0010] (2) The device system provided by the present application comprises a mixing device and a reaction device respectively, so that the mixing and reaction of the reaction raw materials (nitric acid and chlorobenzene) are completed step by step, and the problems of side reactions and safety caused by too high temperature due to too violent heat release in direct reaction are avoided. At the same time, by controlling the conditions (such as the feeding ratio, the flow of raw materials / raw material mixture, etc.) during mixing and reaction, a product with a higher para / ortho ratio can also be obtained, so that more para products can be obtained, and the economic benefit is improved.

[0011] (3) The reaction device in the device system provided by the application adopts a tubular reactor with a large pipe diameter, avoiding the production efficiency and safety problems caused by the blockage of the reaction pipeline in the existing micro-channel reactor. Meanwhile, the reaction device is also provided with a flow control system and a timing system for precisely controlling the reaction temperature and time (the reaction temperature is controlled through the flow control, and at the same time, the reaction time is also affected by the flow), thereby improving the product yield. Meanwhile, the control of the flow ratio of nitric acid and chlorobenzene entering the mixing device realizes a high conversion rate without the use of sulfuric acid catalysis, avoiding the problems of high cost, poor safety and environmental protection caused by the large amount of mixed acid in the mixed acid process. In addition, the remaining nitric acid after the reaction can also be recycled and recycled through subsequent separation devices, recovery devices and the like, further reducing the resource input and saving the production cost.

[0012] (4) The separation device containing an annular gap flow separation device is adopted in the device system provided by the application, so that the rapid (continuous) separation of the reaction material is realized, avoiding the oxidation side reaction and product decomposition reaction caused by the long-term contact of the product with waste nitric acid and air and the like after the reaction, improving the product quality and yield, and reducing the production safety problems caused by the side reaction and by-product.

[0013] (5) The method and device system provided by the application can realize the continuous production of nitrochlorobenzene with high conversion rate, improve the production efficiency, and the device system can also realize the full-automatic production operation by connecting a computer and control software, reduce the on-site personnel arrangement, reduce the manual input, further improve the production safety, and can adjust the equipment operation in a large range according to the actual situation, realizing the production automation and intelligentization. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a process schematic diagram of nitrochlorobenzene prepared by using the device system provided by the application;

[0015] Figure 2 is a structural schematic diagram of the mixing device adopted in the device system provided by the application.

[0016] BRIEF DESCRIPTION OF DRAWINGS

[0017] 1 feed pump with flow meter 2 mixing device 3 reaction device 4 separation device

[0018] 5 feed pipe A 6 feed pipe B (containing 5 branches) DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value, inclusive of both values, and to sub-ranges falling within the specified range. In this context, individual points within a range should be considered as being included within that range, and individual points can be combined to form new ranges, which are to be considered as being included within the present disclosure.

[0020] In the process of preparing nitrochlorobenzene by nitration reaction with chlorobenzene and nitric acid as raw materials and sulfuric acid as catalyst, due to the severe heat release of the reaction, the high reaction temperature and the great danger, in order to control the heat release of the reaction, reduce the side reaction and reduce the danger of the reaction, it is usually necessary to select a special reactor (for example, to select a heat-resistant material, to be equipped with a heat dissipation / cooling device, etc.) to carry out the reaction, and it is usually necessary to monitor the reaction temperature in real time. The inventors of the present application ingeniously found that if sulfuric acid is not added, chlorobenzene and nitric acid are mixed uniformly first, and then the mixture is introduced into the reactor for nitration reaction, and the reaction of chlorobenzene and / or nitric acid in the mixing process is controlled within a certain range, which not only reduces the side reaction, but also improves the proportion of p-nitrochlorobenzene in the product, thereby improving the economic benefit. The inventors also found that the temperature of the material in the mixing device has a certain relationship with the reaction degree of chlorobenzene and / or nitric acid in the mixing process, and by monitoring and controlling the temperature of the material in the mixing device, the reaction degree of the raw materials in the mixing process can be more easily controlled.

[0021] Based on the above findings, the present application provides a method for continuously producing nitrochlorobenzene, which comprises introducing raw material A and raw material B into a mixing device for mixing, and then introducing the obtained raw material mixture into a reaction device for nitration reaction to obtain a reaction product, wherein raw material A and raw material B are one of nitric acid and chlorobenzene (for example, when raw material A is nitric acid, raw material B is chlorobenzene, and when raw material A is chlorobenzene, raw material B is nitric acid), and the raw material mixture comprises nitric acid, chlorobenzene and nitrochlorobenzene, wherein the temperature of the material in the mixing device is not more than 60℃.

[0022] In the present application, the temperature of the raw material introduced into the mixing device is not particularly limited, and in order to facilitate production management, the temperature of the material introduced into the mixing device is usually room temperature (for example, 20-30℃). If the production environment temperature is relatively high, the feeding temperature can also be appropriately reduced.

[0023] According to a preferred embodiment of the present application, the method does not include introducing sulfuric acid into the mixing device and / or the reaction device. That is, the method provided by the present application does not include using sulfuric acid as a catalyst, that is, in the method provided by the present application, the raw materials for the production of nitrochlorobenzene are only nitric acid and chlorobenzene.

[0024] The inventors of the present application have also found in the research that the speed of mixing can be accelerated by contacting one of the raw materials A and the raw material B with the other in batches, so as to achieve the purpose of quickly obtaining a raw material mixture that is uniformly mixed. This way of mixing in batches can also alleviate the situation of the raw materials reacting and thus releasing heat violently after being contacted, reduce the occurrence of side reactions, and improve the production safety.

[0025] According to a preferred embodiment of the present application, the mixing comprises the step of contacting the raw material B with the raw material A in batches, so as to obtain a raw material mixture that is uniformly mixed. The contacting in batches means that the raw material B is gradually added to the raw material A to form the raw material mixture.

[0026] In order to accelerate the mixing speed, improve the uniformity of the raw material mixture, and control the conversion rates of the raw material A and the raw material B in the raw material mixture within the aforementioned ranges, preferably, the raw material B is contacted (and mixed) with the raw material A for 2-10 times, preferably 3-7 times.

[0027] Preferably, the concentration of the nitric acid is not less than 90% by weight, and is preferably 95-98% by weight.

[0028] The inventors of the present application have also found in the research that the change of the flow ratio (volume) of chlorobenzene and nitric acid has a certain influence on the reaction efficiency of the nitration reaction carried out in the reactor and the content ratio of p-nitrochlorobenzene and o-nitrochlorobenzene in the product. By adjusting the volume flow ratio of chlorobenzene and nitric acid fed into the mixing device, the reaction efficiency and the proportion of p-nitrochlorobenzene in the product can be further improved. Moreover, as long as the flow ratio of chlorobenzene and nitric acid is controlled within a certain range, the temperature of the materials in the mixing device will also be controlled within a certain range.

[0029] Preferably, the method further comprises controlling the flow rates of the raw material A and the raw material B, preferably so that the volume flow ratio of chlorobenzene and nitric acid is 1:0.5-1.5. For example, it can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, or can also be any value between any two of the above ratios.

[0030] In the present application, the conditions for mixing are not particularly limited, as long as the materials in the mixing device are kept below 60℃, for example, the mixing can be carried out at room temperature (i.e. without additional heating or cooling treatment of the materials in the mixing device) and normal pressure.

[0031] According to the preferred embodiment of the present application, the reaction conditions in the reaction device include a reaction temperature of 50-130°C, preferably 90-130°C, and a residence time of 3-20 min. Since sulfuric acid is not used as a catalyst in the present application, the heat generated by the nitration reaction of a small amount of nitric acid and chlorobenzene in the raw material mixture is not enough to promote it to quickly enter the reaction state. In order to accelerate the reaction process and improve production efficiency, the method preferably includes heating the raw material mixture introduced into the reaction device to promote it to reach the aforementioned reaction temperature. At the same time, since the nitration reaction of chlorobenzene and nitric acid is an exothermic process, in order to save energy consumption and also to prevent the occurrence of side reactions or dangers caused by excessive temperature, the present application preferably includes the operation of heat insulation of the reaction device to make the reaction heat become one of the heat sources of the reaction device. Preferably, the heat insulation operation makes the temperature change value in the reaction process not more than 5°C. Preferably, the temperature change value in the reaction process is 3°C. The specific way of heat insulation in the present application is not particularly limited as long as the above-mentioned purpose can be achieved.

[0032] According to the preferred embodiment of the present application, the method further includes introducing the reaction product obtained in the reaction device into a separation device to obtain nitrochlorobenzene crude and waste nitric acid.

[0033] The inventors of the present application have also found in the process of research that the use of annular gap flow device for the separation of reaction products can quickly separate nitrochlorobenzene crude and waste nitric acid in the products, and on the other hand, a small amount of unreacted nitric acid and chlorobenzene contained in the reaction product can fully contact and undergo nitration reaction in the centrifugation process in the annular gap flow device, further promoting the improvement of raw material conversion rate and reaction efficiency.

[0034] The present application preferably uses annular gap flow equipment for the separation of reaction products, and preferably the separation conditions of nitrochlorobenzene crude and waste nitric acid in the reaction product in the separation device include a rotation speed of 800-1500 rpm.

[0035] In the present application, the conditions of the nitration reaction make the content of nitrochlorobenzene in the nitrochlorobenzene crude reach more than 90% by weight, preferably more than 95% by weight, more preferably more than 97% by weight, and further preferably more than 99% by weight. For example, it can be 95% by weight, 95.5% by weight, 96% by weight, 96.5% by weight, 97% by weight, 97.5% by weight, 98% by weight, 98.5% by weight, 99% by weight, 99.3% by weight, 99.5% by weight, 99.8% by weight, 99.9% by weight, 100% by weight, or any intermediate value between any two of the above-mentioned values.

[0036] According to the preferred embodiment of the present application, the method further includes the purification of nitrochlorobenzene.

[0037] Preferably, the refining of the nitrochlorobenzene can include steps such as washing (e.g. conventional alkali washing and water washing, etc.), drying, purification, etc. so as to obtain a pure nitrochlorobenzene product. The present application is not particularly limited as to the specific refining method and operation, and any method capable of achieving the refining of nitrochlorobenzene can be applied to the present application.

[0038] In the present application, the waste nitric acid separated by the separation device can be collected and recovered, and after being regenerated, recycled nitric acid is obtained and its concentration is adjusted to the aforementioned range, which is used as raw material for the production of nitrochlorobenzene in the aforementioned method, so as to separate the nitric acid not involved in the reaction from the reaction product and recycle it to the production process, thereby reducing the waste of resources and reducing the pressure of acid emission on the environment. The present application is not particularly limited as to the method of recycling and regenerating the waste nitric acid, and any method capable of treating the waste nitric acid to obtain recycled nitric acid can be applied to the present application, which can be sending the collected waste nitric acid to a special treatment agency for treatment, or self-treatment according to any method for treating waste nitric acid in the prior art.

[0039] The second aspect of the present application provides a device system for continuously producing nitrochlorobenzene, which comprises a mixing device and a reaction device, wherein the mixing device comprises a feed pipe A and a feed pipe B for feeding raw material A and raw material B respectively, so as to obtain a raw material mixture, and then the raw material mixture is fed into the reaction device for nitration reaction to obtain a reaction product.

[0040] According to the preferred embodiment of the present application, the mixing device and / or the reaction device do not comprise a sulfuric acid feed port.

[0041] According to the preferred embodiment of the present application, the mixing device further comprises a temperature monitoring system for detecting the temperature of the raw material mixture flowing out of the mixing device and controlling it to be kept within a limited range (e.g. so that the temperature of the material in the mixing device does not exceed 60°C).

[0042] In the present application, the mixing device is used to uniformly mix the nitric acid and chlorobenzene used as raw materials, and then the mixture is introduced into the reaction device for reaction, so as to improve the reaction efficiency while avoiding the safety problems and side reaction problems caused by the excessive heat release of the reaction caused by the direct contact of nitric acid and chlorobenzene. Any mixing device capable of achieving the above purpose can be applied to the present application. The inventors of the present application have found through repeated experiments that mixing the reaction materials (nitric acid and chlorobenzene) in batches can quickly mix them uniformly and effectively control the heat release during the contact process to prevent side reactions from occurring, thereby ensuring the quality of the product and the safety of the production.

[0043] The mixing device in the device system provided by the present application preferably adopts a mixing device capable of mixing the reaction materials in batches. The way of batch mixing of the mixing device is not particularly limited. According to a preferred embodiment of the present application, the mixing device (refer to Figure 2 ) contains a feeding pipe A for introducing raw materials and a feeding pipe B containing 2-10 branches, and the branches of the feeding pipe B are respectively connected to the feeding pipe A, so that the material B is mixed with the material A in batches in the mixing device to obtain a uniformly mixed raw material mixture, and the material A and the material B are one of nitric acid and chlorobenzene. That is, in the mixing device provided by the present application, the flow of the material B is realized by using the feeding pipe B containing several branches, so as to realize the batch mixing of the material A and the material B, thereby reducing the heat release in the material mixing process, reducing the side reaction while making the reaction more controllable.

[0044] Preferably, in the mixing device, the feeding pipe B contains 3-7 branches, and each branch is connected to the feeding pipe A at equal intervals.

[0045] In order to improve the reaction efficiency and safety, and at the same time improve the content ratio of p-nitrochlorobenzene in the product, preferably, the flow control device I is further installed in the feeding pipe A and / or the feeding pipe B.

[0046] More preferably, the flow control device controls the flow of the material A and / or the material B into the mixing device, so that the volume flow ratio of chlorobenzene and nitric acid is 1:0.5-1.5. For example, it can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, or any value between any two of the above ratios.

[0047] The reaction device is used for nitration of the material mixture to obtain the reaction product containing nitrochlorobenzene (and waste nitric acid). The inventors have found that when the capacity of the reaction device is fixed, the degree of reaction, heat release and reaction time (i.e. the residence time of the material mixture in the reaction device) can be controlled by controlling the flow rate of the introduced raw material mixture, thereby simplifying the equipment and operation required for reaction control, while reducing side reactions and improving safety at a higher conversion rate. In addition, when nitrochlorobenzene is produced using only nitric acid and chlorobenzene as raw materials without using sulfuric acid as a catalyst, the initial heat release of the reaction material cannot reach the reaction temperature, so additional heating equipment is required to heat the raw material mixture in the reaction device. Since the nitration reaction of nitric acid and chlorobenzene is an exothermic process, the heat released by the material initially introduced into the reaction device for reaction can be used as the heat source for the subsequent material introduced into the reaction device for reaction, thereby saving energy consumption and reducing cooling and temperature control operations. In order to prevent the loss of reaction heat, a heat preservation device can be provided in the reaction device.

[0048] According to a preferred embodiment of the present application, the reaction device is a tubular reactor containing at least one of a heating device, a heat preservation device and a flow control device II.

[0049] Preferably, the heating device and / or the heat preservation device allow the reaction temperature in the reaction device to be 50-130°C, preferably 90-130°C.

[0050] Preferably, the heat preservation device allows the temperature change during the reaction to be no more than 5°C. Preferably, it is 3°C.

[0051] Preferably, the flow control device II in the reaction device controls the residence time of the material in the reaction device to be 3-20 min. The residence time of the material refers to the time period from the introduction of the reaction mixture into the reaction device to the removal of the reaction product from the reaction device. In order to further simplify the operation, the present application preferably uses a reaction device with a fixed volume (effective volume) or sets a rated volume in the reaction device (the set rated volume ≤ the effective volume of the reaction device), and when the reaction mixture is introduced (at a certain flow rate) to fill the effective volume or the set rated volume of the reaction device, the reaction product is removed from the reaction device. Therefore, the residence time of the material is the time for the raw material mixture to fill the reaction device at a certain flow rate.

[0052] In order to prevent the pipe of the reaction device from being blocked, preferably, for the tubular reactor with an effective volume of 60 mL, the diameter of the pipe used is not less than 2 mm, preferably 2-5 mm. When the effective volume of the tubular reactor changes, the diameter of the pipe used also changes proportionally.

[0053] The inventor of the present application has also found in the course of research that the annular gap flow separation device can easily and quickly separate a mixture containing components with different specific gravities, and is very suitable for separating reaction products obtained in a reaction device, which not only can reduce the contact between nitrochlorobenzene and the remaining (waste nitric acid) to reduce the occurrence of side reactions, but also can separate nitrochlorobenzene in time to reduce the oxidation and deterioration of the product and improve the product quality. Moreover, when using the annular gap flow device for separation, the unreacted (or not completely reacted) components in the material introduced therein can further react therein, thereby improving the reaction conversion rate and the yield of nitrochlorobenzene.

[0054] According to a preferred embodiment of the present application, the device system further comprises a separation device.

[0055] Preferably, the separation device is a continuous flow reactor comprising an annular gap flow separation device.

[0056] Preferably, the separation device further comprises a waste nitric acid outlet and a nitrochlorobenzene crude product outlet.

[0057] Since the device system provided by the present application can control the reaction temperature by accurately controlling the flow of the material (such as the flow of the raw material, the flow of the raw material mixture, etc.), the nitration process of chlorobenzene is more controllable, and the nitration reaction can be completed without the need for sulfuric acid catalysis, and nitrochlorobenzene can be obtained at a high yield. Therefore, the reaction product obtained in the reaction device of the present application does not contain sulfuric acid (i.e. the mixed acid component commonly used in the preparation of nitrochlorobenzene in the art), so that the nitric acid in the remaining part after the separation of nitrochlorobenzene can be more easily recovered and reused in the preparation process of nitrochlorobenzene after regeneration treatment, reducing the waste of resources and reducing the environmental pressure.

[0058] According to a preferred embodiment of the present application, the device system further comprises a recovery device, which preferably comprises a waste nitric acid recovery device and an optional waste nitric acid regeneration recycling device.

[0059] Preferably, the recovery device is connected to the waste nitric acid outlet of the separation device.

[0060] In order to obtain refined nitrochlorobenzene products, according to a preferred embodiment of the present application, the device system further comprises a refining device, which preferably comprises a washing device and a drying device. The washing device is used to wash the nitrochlorobenzene crude product obtained by the separation device, so as to remove organic acids and inorganic acids therein. The drying device is used to dehydrate and dry the washed nitrochlorobenzene crude product.

[0061] Preferably, the refining device is connected to the nitrochlorobenzene crude product outlet of the separation device.

[0062] Preferably, further separation device can also be included in the refining device for separating o-nitrochlorobenzene and p-nitrochlorobenzene, so as to obtain the corresponding pure products. The device for separating o-nitrochlorobenzene and p-nitrochlorobenzene and the specific method for separating o-nitrochlorobenzene and p-nitrochlorobenzene in the present application are not particularly limited, and the skilled in the art can select appropriate separation device and method according to the actual situation and needs. For example, rectification method, continuous melt crystallization method and the like can be used to separate o-nitrochlorobenzene and p-nitrochlorobenzene in the refined nitrochlorobenzene.

[0063] The third aspect of the present application provides the use of the device system and method as described above in the industrial production of nitrochlorobenzene. In particular, the use in the continuous production of nitrochlorobenzene. The continuous production refers to the continuous reaction in the production process of nitrochlorobenzene, and the production process does not need to stop during the feeding of raw materials and the leading out of products.

[0064] The present application will be described in detail by way of examples below. It should be understood that the following examples are only used to illustrate and further explain the content of the present application, and are not used to limit the present application.

[0065] In the following examples, the concentration of nitric acid is 98% by weight. Unless otherwise specified, the reagents used in the following examples are commercially available from regular chemical reagent suppliers, and the purity is analytical pure.

[0066] In the following examples, the conversion rate of chlorobenzene (total) is calculated by the formula: 100 - raw material content / 100%. The content of nitrochlorobenzene in the obtained crude nitrochlorobenzene is detected by gas chromatography. The obtained nitrochlorobenzene refining product is detected by gas chromatography, and the content of o-nitrochlorobenzene and p-nitrochlorobenzene in the obtained nitrochlorobenzene refining product is calculated by area normalization method according to the obtained gas chromatogram, and the p / o-nitrochlorobenzene ratio (the weight ratio of p-nitrochlorobenzene and o-nitrochlorobenzene in the product) is calculated according to the content. The reaction temperature refers to the temperature during the reaction in the reaction device after the raw material mixture is introduced into the reaction device.

[0067] Example 1

[0068] (1) Raw material mixing: refer to the operation process shown in Figure 1 The chlorobenzene and nitric acid are introduced into the mixing device (structure reference Figure 2), wherein the nitric acid is introduced into the mixing device through a feed pipe B (containing 5 branches connected to the feed pipe A at equal intervals), and the chlorobenzene is introduced into the mixing device through a feed pipe A. A flow meter I-1 (feed pipe A) and a flow meter I-2 (feed pipe B, arranged before the first branch in the feed direction) are arranged at the front ends of the feed pipes A and B, respectively, for controlling the flow rate of the raw material feed. The flow rate of the nitric acid feed is adjusted to 5 mL / min, and the flow rate of the chlorobenzene feed is adjusted to 5 mL / min. After the nitric acid and chlorobenzene are fully mixed in the mixing device, a raw material mixture is obtained. The mixing device is provided with a temperature monitoring device, but no additional heating or cooling device is provided, and the temperature of the material in the mixing device is controlled to be no more than 60°C (about 35-45°C) according to the aforementioned feed flow rate.

[0069] (2) Nitration reaction: The raw material mixture is introduced into a reaction device (a tubular reactor with a total effective volume of 60 mL and a reaction tube with a diameter of 2 mm), and a flow meter II-1 and a flow meter II-2 are arranged at the inlet of the raw material reactant and the outlet of the reaction product of the reaction device, respectively, for controlling the flow rate of the raw material mixture feed. The flow rate of the raw material mixture is adjusted to 10 mL / min, so that the residence time of the raw material mixture in the reaction device is 6 min, and the reaction product obtained flows out at a flow rate of 10 mL / min. The reaction device is provided with a heating device, a heat preservation device and a temperature monitoring system, and the temperature during the reaction is monitored. When the temperature of the reaction system cannot reach the set reaction temperature due to the heat generated by the reaction of chlorobenzene and nitric acid, the reaction device is heated by the heating device to reach the reaction temperature, and the heat preservation device is used to prevent heat loss of the reaction device. The highest temperature during the reaction is about 97°C, the lowest temperature is about 93°C, and the average temperature is about 95°C.

[0070] (3) Product separation: The reaction product is introduced into a separation device (a centrifugal extraction continuous flow reactor) for further reaction and product separation at a rotation speed of 1000 rpm. A crude nitrochlorobenzene and waste nitric acid are obtained.

[0071] (4) Product purification and nitric acid recovery: The separation device is connected to a waste nitric acid recovery device and a nitrochlorobenzene purification device (not shown in the figure) respectively. Figure 1 The recovered waste nitric acid is treated to adjust the concentration to 98% by weight, and then can be used as raw material for the raw material mixing step. The crude nitrochlorobenzene is introduced into the purification device and treated according to the following steps to obtain purified nitrochlorobenzene.

[0072] The crude nitrochlorobenzene is washed once with 5% by weight sodium carbonate solution and then washed once with water, and then vacuum dewatered, and then subjected to industrial melt crystallization to obtain the refined nitrochlorobenzene. The conversion rate of chlorobenzene is 99%, the content of nitrochlorobenzene in the crude product is 98% by weight, and the ratio of p- / o-nitrochlorobenzene is 2.12:1.

[0073] Example 2

[0074] The method of Example 1 is used, except that in step (1) the feed flow rate of chlorobenzene is adjusted to 3 mL / min and the feed flow rate of nitric acid is adjusted to 3 mL / min, and the temperature of the material in the mixing device is not allowed to exceed 60°C (approximately in the range of 35-45°C). In step (2) the feed flow rate of the raw material mixture is adjusted to 6 mL / min, so that the residence time is 10 min, and the discharge flow rate of the reaction product is 6 mL / min. It is detected that the highest temperature during the reaction is about 95°C, the lowest temperature is about 91°C, and the average temperature is about 93°C. It is detected that the conversion rate of chlorobenzene is 91%, the content of nitrochlorobenzene in the crude product is 90% by weight, and the ratio of p- / o-nitrochlorobenzene is 2.31:1.

[0075] Example 3

[0076] The method of Example 1 is used, except that in step (1) the feed flow rate of chlorobenzene is adjusted to 4 mL / min and the feed flow rate of nitric acid is adjusted to 4 mL / min, and the temperature of the material in the mixing device is not allowed to exceed 60°C (approximately in the range of 35-45°C). In step (2) the feed flow rate of the raw material mixture is adjusted to 8 mL / min, so that the residence time is 7.5 min, and the discharge flow rate of the reaction product is 8 mL / min. It is detected that the highest temperature during the reaction is about 105°C, the lowest temperature is about 101°C, and the average temperature is about 103°C. It is detected that the conversion rate of chlorobenzene is 95%, the content of nitrochlorobenzene in the crude product is 93% by weight, and the ratio of p- / o-nitrochlorobenzene is 2.47:1.

[0077] Example 4

[0078] The method of Example 1 is used, except that in step (1) the feed flow rate of chlorobenzene is adjusted to 6 mL / min and the feed flow rate of nitric acid is adjusted to 8 mL / min, and the temperature of the material in the mixing device is not allowed to exceed 60°C (approximately in the range of 35-45°C). In step (2) the feed flow rate of the raw material mixture is adjusted to 12 mL / min, so that the residence time is 4 min, and the discharge flow rate of the reaction product is 14 mL / min. It is detected that the highest temperature during the reaction is about 125°C, the lowest temperature is about 121°C, and the average temperature is about 123°C. It is detected that the conversion rate of chlorobenzene is 99.5%, the content of nitrochlorobenzene in the crude product is 98.5% by weight, and the ratio of p- / o-nitrochlorobenzene is 2.53:1.

[0079] Example 5

[0080] The method of Example 1 was used, except that in Step (1), the feed flow rate of chlorobenzene was adjusted to 8 mL / min, the feed flow rate of nitric acid was adjusted to 8 mL / min, and the temperature of the mixture in the mixing device was not allowed to exceed 60°C (about 35-45°C). In Step (2), the feed flow rate of the raw material mixture was adjusted to 16 mL / min, so that the residence time was 3.75 min, and the discharge flow rate of the reaction product was 16 mL / min. It was detected that the highest temperature during the reaction was about 125°C, the lowest temperature was about 121°C, and the average temperature was about 123°C. It was detected that the conversion rate of chlorobenzene was 99.5%, the content of nitrochlorobenzene in the crude product was 99% by weight, and the ratio of p- / o-nitrochlorobenzene was 2.52:1.

[0081] Example 6

[0082] The method of Example 1 was used, except that in Step (1), the feed flow rate of chlorobenzene was adjusted to 6 mL / min, the feed flow rate of nitric acid was adjusted to 6 mL / min, and the temperature of the mixture in the mixing device was not allowed to exceed 60°C (about 35-45°C). In Step (2), the feed flow rate of the raw material mixture was adjusted to 12 mL / min, so that the residence time was 5 min, and the discharge flow rate of the reaction product was 12 mL / min. It was detected that the highest temperature during the reaction was about 128°C, the lowest temperature was about 124°C, and the average temperature was about 126°C. It was detected that the conversion rate of nitrochlorobenzene was 100%, the content of nitrochlorobenzene in the crude product was 99.5% by weight, and the ratio of p- / o-nitrochlorobenzene was 2.42:1.

[0083] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for producing nitrochlorobenzene, characterized in that, The method includes introducing raw material A and raw material B into a mixing device for mixing, and then introducing the obtained raw material mixture into a reaction device for nitration reaction to obtain reaction products. The raw material A and raw material B are respectively one of nitric acid and chlorobenzene, and the raw material mixture includes nitric acid, chlorobenzene and nitrochlorobenzene. The temperature of the materials in the mixing device does not exceed 60°C. The method does not include the step of introducing sulfuric acid into the mixing device and / or reaction device; the method also includes controlling the flow rates of raw material A and raw material B so that the volume flow rate ratio of chlorobenzene and nitric acid is 1:1-1.5; the reaction conditions in the reaction device include: reaction temperature 90-130℃, residence time 3-20min; The mixing device includes a feed pipe A for introducing raw materials and a feed pipe B containing 2-10 branches. The branches of the feed pipe B are respectively connected to the feed pipe A, so that material B is mixed with material A in the mixing device in stages to obtain a uniformly mixed raw material mixture. The reaction apparatus is a tubular reactor containing at least one of a heating device, a heat preservation device, and a flow control device.

2. The method according to claim 1, wherein, In the mixing device, the feed pipe B includes 3-7 branches, and each branch is connected to the feed pipe A at equal intervals.

3. The method according to claim 1, wherein, The concentration of the nitric acid is not less than 90% by weight.

4. The method according to claim 3, wherein, The concentration of the nitric acid is 95-98% by weight.

5. The method according to claim 1, wherein, The method also includes keeping the reaction apparatus warm so that the temperature change during the reaction process does not exceed 5°C.

6. The method according to claim 1, wherein, The method further includes introducing the reaction products obtained in the reaction apparatus into a separation device to obtain crude nitrochlorobenzene and waste nitric acid.

7. The method according to claim 6, wherein, The separation conditions for nitrochlorobenzene and waste nitric acid in the reaction products in the separation device include a rotation speed of 800-1500 rpm; the separation device is a continuous flow reactor including annular flow separation equipment.

8. The method according to claim 1, wherein, The method also includes the purification of nitrochlorobenzene.

9. The method according to claim 8, wherein, The refining of nitrochlorobenzene includes at least one of washing and drying of crude nitrochlorobenzene.

10. A continuous production apparatus system for nitrochlorobenzene, characterized in that, The device system includes a mixing device (2) and a reaction device (3). The mixing device includes a feed pipe A (5) and a feed pipe B (6) for introducing raw material A and raw material B respectively to obtain a raw material mixture. The raw material mixture is then introduced into the reaction device for nitration reaction to obtain the reaction product. The mixing device and / or reaction device does not include a sulfuric acid inlet; the feed pipe A and / or feed pipe B are also equipped with a flow control device I; The mixing device includes a feed pipe A for introducing raw materials and a feed pipe B containing 2-10 branches. The branches of the feed pipe B are respectively connected to the feed pipe A, so that material B is mixed with material A in the mixing device in stages to obtain a uniformly mixed raw material mixture. The reaction apparatus is a tubular reactor containing at least one of a heating device, a heat preservation device, and a flow control device II.

11. The apparatus system according to claim 10, wherein, In the mixing device, the feed pipe B includes 3-7 branches, and each branch is connected to the feed pipe A at equal intervals.

12. The apparatus system according to claim 10, wherein, The device system also includes a separation device (4).

13. The apparatus system according to claim 12, wherein, The system also includes a refining device, which includes a washing device and a drying device.

14. The apparatus system according to claim 12, wherein, The separation device includes annular flow separation equipment.

15. The application of the method according to any one of claims 1-9 and the apparatus system according to any one of claims 10-14 in the industrial production of nitrochlorobenzene.

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