CN113967454A - Device and method for high-selectivity continuous synthesis of mixed dinitrobenzene - Google Patents
Device and method for high-selectivity continuous synthesis of mixed dinitrobenzene Download PDFInfo
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- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
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Abstract
The invention relates to a device and a method for high-selectivity continuous synthesis of mixed dinitrobenzene, which comprises a mixed acid feeding pipeline, a nitrobenzene feeding pipeline, a micro mixer, a micro reactor, a time delay reactor and a post-treatment system, wherein the micro mixer is provided with two feeding channels, the mixed acid feeding pipeline is connected with a first feeding channel, the nitrobenzene feeding pipeline is connected with a second feeding channel, the mixed acid feeding pipeline is provided with a first metering pump, the nitrobenzene feeding pipeline is provided with a second metering pump, and the micro mixer, the micro reactor, the time delay reactor and the post-treatment system are sequentially connected in series; the micro mixer comprises a micro mixer base plate and first heat exchange plates arranged on two sides of the micro mixer base plate, a plurality of first dispersion mixing unit groups are arranged in the micro mixer, the micro reactor comprises a micro reactor base plate and second heat exchange plates arranged on two sides of the micro reactor base plate, and a plurality of second dispersion unit groups are arranged in the micro reactor base plate. The invention realizes high conversion rate and high selectivity of nitration reaction.
Description
Technical Field
The invention relates to the field of fine chemicals production, in particular to a device and a method for high-selectivity continuous synthesis of mixed dinitrobenzene.
Background
Dinitrobenzene is a generic name for m-dinitrobenzene, p-dinitrobenzene and o-dinitrobenzene, is mainly used for preparing dyes, paints and coatings, and is also a precursor for producing explosives (TNT). The synthesis of the dinitrobenzene comprises two-step nitration of benzene and one-step nitration of nitrobenzene, while the mixed acid nitration process has continuous and intermittent modes, but the traditional intermittent kettle type nitration process has the problems of large temperature difference in the production process, easy explosion, large waste acid and waste water amount, large danger in the driving process and the like, and the continuous method has the advantages of small equipment, large production, high efficiency, convenience in automatic control and the like. In addition, from the technological aspect, the nitration technology is mainly divided into two nitration technologies of isothermal nitration and adiabatic nitration, adiabatic nitration needs to be operated under closed pressure in order to prevent volatilization of nitrobenzene, loss of heat and oxidation of air, the content of generated waste acid is low, the water content is high, because the reaction temperature is higher than the boiling point of reactants, the reaction pressure is higher than the normal pressure, pressure-resistant equipment is needed, special material tantalum is required for flash evaporation equipment, and the investment cost is high. A large amount of heat energy concentrated waste acid is generated after the isothermal nitration process reaction is finished, the energy waste is large, the reaction time is long, and a large amount of byproducts are generated in the process, but the isothermal nitration process has the characteristics of simple equipment, investment saving, high yield (the yield of nitrobenzene is more than or equal to 95 percent) and the like, and the tank type series process is widely adopted in China at present.
In the prior art, a nitration process for synthesizing mixed dinitrobenzene in a microchannel is also available, for example, patent CN112979472A discloses a method for continuously producing dinitrobenzene, which adopts multistage microchannel nitration, and water needs to be separated between each stage to obtain better dinitrobenzene yield, and the use amount of sulfuric acid is less, but the device flow is complex, the requirement on equipment material is high, the investment is large, the device is not suitable for large-scale production, and the meta selectivity is not more than 88%.
Disclosure of Invention
The invention aims to provide a device and a method for high-selectivity continuous synthesis of mixed dinitrobenzene, wherein the device adopts a micro mixer, a micro reactor and a time-delay reactor in series connection, the micro mixer realizes full mixing and contact of two materials, the micro reactor realizes the purposes of material reaction and enhanced mass and heat transfer so as to realize that reaction control is carried out at a lower temperature, and the time-delay reactor ensures sufficient reaction time so as to improve the conversion rate of raw materials and finally realize high conversion rate and high selectivity of nitration reaction.
The purpose of the invention is realized by the following technical scheme:
a device for high-selectivity continuous synthesis of mixed dinitrobenzene comprises a mixed acid feeding pipeline, a nitrobenzene feeding pipeline, a micro mixer, a micro reactor, a time-delay reactor and a post-treatment system, wherein the micro mixer is provided with a first feeding channel and a second feeding channel, the mixed acid feeding pipeline is connected with the first feeding channel, the nitrobenzene feeding pipeline is connected with the second feeding channel, the mixed acid feeding pipeline is provided with a first metering pump, the nitrobenzene feeding pipeline is provided with a second metering pump, and the micro mixer, the micro reactor, the time-delay reactor and the post-treatment system are sequentially connected in series; the micro mixer comprises a micro mixer base plate and first heat exchange plates arranged on two sides of the micro mixer base plate, a first dispersion mixing unit group is arranged in the micro mixer base plate, the micro reactor comprises a micro reactor base plate and second heat exchange plates arranged on two sides of the micro reactor base plate, and a second dispersion unit group is arranged in the micro reactor base plate.
Be equipped with first pan feeding passageway, second pan feeding passageway, discharging channel, first dispersion mixing unit group and first connecting channel in the micromixer base plate, wherein each first dispersion mixing unit group establishes ties in proper order through the first connecting channel that corresponds respectively, and the first dispersion mixing unit group pan feeding end that is located the input side is equipped with the mixed interface runner of taking two venturi types undergauge passageways, just first pan feeding passageway and second pan feeding passageway respectively with the venturi type undergauge access connection that corresponds on the mixed interface runner, the first dispersion mixing unit group discharging end that is located the output side with discharging channel connects.
The micro-reactor base plate is internally provided with a reaction feeding channel, a reaction discharging channel, a second dispersion mixing unit group and a second connecting channel, wherein each second dispersion unit group is sequentially connected in series through the corresponding second connecting channel, the input end of the second dispersion mixing unit group positioned at the input side is connected with the reaction feeding channel, and the output end of the second dispersion mixing unit group positioned at the output side is connected with the reaction discharging channel.
First dispersion mixing unit group includes a plurality of first dispersion mixing unit who establishes ties in proper order, second dispersion mixing unit group includes a plurality of second dispersion mixing unit who establishes ties in proper order, first dispersion mixing unit with second dispersion mixing unit structure is the same, all includes the dispersion runner and joins the runner.
The first heat exchange plate and the second heat exchange plate are identical in structure, and are internally provided with a heat exchange medium input runner, a heat exchange medium output runner, bending runner sections and connecting runner sections, wherein the bending runner sections are sequentially connected in series through the corresponding connecting runner sections, the input end of the bending runner section at the input side is connected with the heat exchange medium input runner, and the output end of the bending runner section at the output side is connected with the heat exchange medium output runner.
The number of the microreactors is at least one, and the number of the time-delay reactors is at least one.
The post-treatment system comprises a waste acid and nitration product separator, a prewashing device, a prewashing separator, an alkaline washing device, an alkaline washing separator, a water washing device and a water washing separator which are sequentially connected in series.
A method for continuously synthesizing mixed dinitrobenzene according to the high selectivity comprises the following steps:
step one, preparing a mixed acid solution of nitric acid and sulfuric acid;
pumping mixed acid into the micro mixer through a first metering pump, pumping nitrobenzene into the micro mixer through a second metering pump, and controlling the molar ratio of the nitrobenzene, the nitric acid and the sulfuric acid by controlling the pumping rate of the first metering pump and the second metering pump;
controlling the temperature of the first heat exchange plate and the second heat exchange plate to be 60-80 ℃, controlling the total residence time of reaction materials in the micro mixer, the micro reactor and the delay reactor to be 150-600 seconds, mixing and contacting two streams of raw material liquid of nitrobenzene and mixed acid in the micro mixer, and reacting in the micro reactor, wherein the reaction formula is as follows:
step four: and the reaction materials are output from the time delay reactor, enter a post-treatment system and are separated to obtain a target product.
In the first step, the mixed acid is prepared from nitric acid, sulfuric acid and water, the mass concentration of the water in the mixed acid is 3% -15%, the nitric acid is fuming nitric acid with the concentration of more than 98%, the sulfuric acid is concentrated sulfuric acid with the concentration of more than 98%, and the temperature of the process of preparing the mixed acid is controlled to be below 40 ℃.
In the second step, the molar ratio of the materials is controlled as nitrobenzene: nitric acid: sulfuric acid 1: (1.05-1.25): (1.5-2.3), the flowing pressure of the nitrobenzene and the mixed acid in the microchannel reactor is 0-1 MPa.
The invention has the advantages and positive effects that:
1. the device adopts a series structure of a micro mixer, a micro reactor and a time delay reactor, wherein the micro mixer realizes the full mixing contact of two materials, the micro reactor realizes the purposes of material reaction and enhanced mass and heat transfer so as to realize the reaction control at lower temperature, and the time delay reactor ensures enough reaction time so as to improve the conversion rate of raw materials and finally realize high conversion rate and high selectivity of nitration reaction.
2. The invention adopts nitric acid, sulfuric acid and water to prepare mixed acid, and the total molar ratio of the raw materials is nitrobenzene: nitric acid: sulfuric acid 1: (1.05-1.25): (1.5-2.3), under the condition, the mixed acid has stronger nitration capability and can provide a faster nitration reaction speed, so that the reaction can be operated at 60-80 ℃.
3. Compared with a common reaction kettle, the device has the advantages that the operation safety is the most important in a dangerous process, the liquid holdup of the microchannel reactor is less and is several orders of magnitude smaller than that of the traditional kettle type reaction kettle, the mass and heat transfer efficiency in the microchannel reactor is 1-3 orders of magnitude higher than that of the kettle type reaction kettle, the heat generated by the reaction can be taken away quickly, and the possibility of serious accidents caused by the accumulated heat release of a large amount of dangerous materials is completely eradicated.
4. Compared with other prior art, the method has the advantages of high conversion rate (more than 99.5%) which is not lost in other art, excellent meta-selectivity (more than 88%), very low para-selectivity (especially less than 0.25% at the reaction temperature of 60 ℃), and negligible para-product in the subsequent separation process, thereby saving a great deal of energy consumption.
Drawings
FIG. 1 is a schematic structural view of the apparatus of the present invention,
figure 2 is a schematic diagram of the micro-mixer structure of figure 1,
figure 3 is a schematic diagram of the micro-mixer substrate structure of figure 2,
figure 4 is an enlarged schematic view of the first dispersive mixing unit of figure 3,
figure 5 is a schematic diagram of a first heat exchange plate structure in figure 2,
FIG. 6 is a schematic structural view of a microreactor base plate in the microreactor of FIG. 1.
Wherein, 1 is a mixed acid feeding pipeline, 101 is a first metering pump, 102 is a first feeding tank, 2 is a nitrobenzene feeding pipeline, 201 is a second metering pump, 202 is a second feeding tank, 3 is a micro mixer, 31 is a micro mixer base plate, 311 is a first feeding channel, 312 is a second feeding channel, 313 is a discharging channel, 314 is a mixing interface channel, 315 is a first dispersion mixing unit group, 3151 is a first dispersion mixing unit, 316 is a first connecting channel, 317 is a dispersion channel, 318 is a confluence channel, 32 is a first heat exchange plate, 321 is a heat exchange medium input channel, 322 is a heat exchange medium output channel, 323 is a bending channel section, 324 is a connecting channel section, 4 is a microreactor, 41 is a microreactor base plate, 411 is a reaction feeding channel, 412 is a reaction discharging channel, 413 is a second dispersion mixing unit group, 4131 is a second dispersion mixing unit, 414 is a second connecting channel, 5 is a time delay reactor, 6 is a post-treatment system.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1 to 6, the invention comprises a mixed acid feeding pipeline 1, a nitrobenzene feeding pipeline 2, a micro-mixer 3, a micro-reactor 4, a time-delay reactor 5 and a post-treatment system 6, wherein as shown in fig. 2 to 3, the micro-mixer 3 is provided with a first feeding channel 311 and a second feeding channel 312, the mixed acid feeding pipeline 1 is connected with the first feeding channel 311, the nitrobenzene feeding pipeline 2 is connected with the second feeding channel 312, the mixed acid feeding pipeline 1 is provided with a first metering pump 101, the nitrobenzene feeding pipeline 2 is provided with a second metering pump 201, and the micro-mixer 3, the micro-reactor 4, the time-delay reactor 5 and the post-treatment system 6 are sequentially connected in series through pipelines.
As shown in fig. 2 to 3, the micro mixer 3 includes a micro mixer substrate 31 and first heat exchanging plates 32 disposed on two sides of the micro mixer substrate 31, a first feeding channel 311, a second feeding channel 312, a discharging channel 313, a first dispersive mixing unit group 315 and a first connecting channel 316 are disposed in the micro mixer substrate 31, wherein each first dispersive mixing unit group 315 is sequentially connected in series through the corresponding first connecting channel 316, a mixing interface channel 314 with two venturi-type reducing channels is disposed at a feeding end of the first dispersive mixing unit group 315 located at an input side, the first feeding channel 311 and the second feeding channel 312 are connected to the corresponding venturi-type reducing channels on the mixing interface channel 314, and a discharging end of the first dispersive mixing unit group 315 located at an output side is connected to the discharging channel 313. Such venturi-type reduced diameter channels are well known in the art.
As shown in fig. 3, the first dispersing and mixing unit group 315 includes a plurality of first dispersing and mixing units 3151 connected in series in sequence, as shown in fig. 4, the first dispersing and mixing unit 3151 includes a dispersing flow channel 317 and a converging flow channel 318, and the converging flow channel 318 of each first dispersing and mixing unit 3151 is connected to the dispersing flow channel 317 of the adjacent first dispersing and mixing unit 3141, so as to realize continuous dispersing and mixing of the materials.
As shown in fig. 5, a heat exchange medium input flow channel 321, a heat exchange medium output flow channel 322, a bent flow channel section 323, and a connection flow channel section 324 are arranged in the first heat exchange plate 32, wherein each bent flow channel section 323 is sequentially connected in series through a corresponding connection flow channel section 324, the bent flow channel section 323 ensures the heat exchange area of the whole substrate, the input end of the bent flow channel section 323 at the input side is connected with the heat exchange medium input flow channel 321, and the output end of the bent flow channel section 323 at the output side is connected with the heat exchange medium output flow channel 322. The heat exchange plate 32 realizes heat exchange with the micro mixer base plate 31 through input and output of heat exchange media, so that the temperature of the base plate meets the requirement, and the heat exchange media can adopt fluids such as hot water and the like.
The microreactor 4 comprises a microreactor base plate 41 and second heat exchange plates arranged on two sides of the microreactor base plate 41, as shown in fig. 6, a reaction feeding channel 411, a reaction discharging channel 412, a second dispersion mixing unit group 413 and second connecting channels 414 are arranged in the microreactor base plate 41, wherein each second dispersion unit group 413 is sequentially connected in series through the corresponding second connecting channels 414, the input end of the second dispersion mixing unit group 413 positioned on the input side is connected with the reaction feeding channel 411, the output end of the second dispersion mixing unit group 413 positioned on the output side is connected with the reaction discharging channel 412, the reaction feeding channel 411 is connected with a discharging channel 313 in the micromixer base plate 31 through a pipeline, and the reaction discharging channel 412 is connected with the input end of the time-delay reactor 5 through a pipeline. The structure and the working principle of the second heat exchange plate are the same as those of the first heat exchange plate 32, in addition, the second dispersing and mixing unit group 413 comprises a plurality of second dispersing and mixing units 4131 which are sequentially connected in series, and the structure of the second dispersing and mixing units 4131 is the same as that of the first dispersing and mixing units 315, except that the structural parameters such as the size and the like are different. The reaction materials can pass through one or a plurality of micro reactors 4 in sequence after flowing out from the micro mixer 3, and the number of the micro reactors 4 is designed according to the actual requirement.
The delay reactor 5 is made of a stainless steel pipeline disc with the diameter of phi 3 and is used for prolonging the retention time of materials in a pipeline. The reaction materials can pass through one or a plurality of time delay reactors 5 in sequence after flowing out from the last microreactor 4, and the number of the time delay reactors 5 is designed according to actual needs.
As shown in fig. 1, the post-treatment system 6 comprises a waste acid and nitrated product separator, a prewasher, an alkaline cleaner, a water cleaner and a water cleaner which are connected in series in sequence, wherein the waste acid and nitrated product separator separates waste acid, and the nitrated product sequentially passes through the prewasher, the alkaline cleaner, the water cleaner and the water cleaner to finally form a product. The waste acid and nitration product separator, the prewasher, the prewashing separator, the alkaline cleaner, the alkaline cleaning separator, the water scrubber and the water scrubber are all known in the art.
As shown in fig. 1, the mixed acid feeding pipeline 1 is communicated with a first feeding tank 102 for loading mixed acid, and the nitrobenzene feeding pipeline 2 is communicated with a second feeding tank 202 for loading nitrobenzene.
The working principle of the invention is as follows:
the reaction route diagram of the microchannel synthesis method is as follows:
according to the invention, nitrobenzene is used as an initial raw material, mixed acid is used as a nitration reagent, the mixed acid is prepared from nitric acid, sulfuric acid and water, the mass concentration of water in the mixed acid is 3% -15%, the nitric acid is fuming nitric acid with the concentration of more than 98%, the sulfuric acid is concentrated sulfuric acid with the concentration of more than 98%, the concentration of the nitrobenzene is more than 99%, and the above are industrial products.
When the invention takes nitrobenzene as raw material to synthesize dinitrobenzene, the total molar ratio of the raw materials is nitrobenzene: nitric acid: sulfuric acid 1: (1.05-1.25): (1.5-2.3), under the conditions, the mixed acid has strong nitration capability and can provide a fast nitration reaction speed, so that the reaction can be operated at 60-80 ℃, and heat exchange plates are arranged on two sides of the micro mixer 3 and the micro reactor 4 to ensure the reaction temperature.
The invention can control the ratio of the speed of two materials by a first metering pump 101 and a second metering pump 102, further obtain the desired molar ratio of nitrobenzene and mixed acid, the material flow feeding speed is selected based on the maximum pressure of the metering pumps and the mixing effect of a micromixer 3 and a microreactor 4, the optimal reaction speed is not easy to obtain when the material flow feeding speed is lower, the overpressure stop is easy when the material flow feeding speed is higher, the higher the reaction speed is, but the heat exchange capability of the reactor can not be kept up to the high possibility, and the temperature runaway is easy to cause. Therefore, the proper flux can be selected according to specific experiments, and the complete reaction in the time delay reactor 5 is ensured, so that the nitrobenzene is converted into the dinitrobenzene as far as possible, and the better conversion rate and selectivity are obtained.
The speed of pumping the initial nitrobenzene and the mixed acid into the micro mixer 3 is preferably set according to the actual proportioning requirement, the flow pressure of the nitrobenzene and the mixed acid in the micro channel reactor is preferably 0-1 MPa, and the residence time of reactants in the micro mixer 3 and the micro reactor 4 is preferably 150-600 seconds.
The invention lists a plurality of embodiments as shown in the following table 1, wherein, fuming nitric acid (98 percent or more) and concentrated sulfuric acid (98 percent or more) are adopted in each embodiment to prepare mixed acid, and the temperature of the mixed acid preparation process is controlled below 40 ℃. Under the condition of normal temperature, the mixed acid and the nitrobenzene are continuously pumped into a micro-channel mixer 3 and a micro-channel reactor 4 for reaction at the temperature of 60 ℃, 70 ℃ and 80 ℃. Controlling the molar ratio of nitrobenzene to nitric acid to sulfuric acid to be 1: 1.05-1.25: 1.5-2.3, and the specific conditions are shown in the following table 1.
TABLE 1
The selectivity advantages of the present invention over existing commercial processes and other patents are specified in table 2 below.
TABLE 2
| M-dinitrobenzene selectivity (%) | Selectivity for dinitrobenzene (%) | |
| Example 1 | 91.52 | 0.20 |
| Industrial production | 85-88 | 2-3 |
| CN 112552180A | 87.5 | 2.41 |
As can be seen from the above tables 1 and 2, when the reaction temperature of the invention is in the range of 60-80 ℃, the selectivity of m-dinitrobenzene is more than 88% and higher than the prior art level, while when the reaction temperature of the invention is in the range of 60-70 ℃, the selectivity of m-dinitrobenzene is higher than the prior art level and the selectivity of p-dinitrobenzene is lower than the prior art level, especially at 60 ℃, the selectivity of p-dinitrobenzene is less than 0.25%, the component can be ignored in the subsequent separation process, and a large amount of separation energy consumption is saved.
Claims (10)
1. A device for high-selectivity continuous synthesis of mixed dinitrobenzene is characterized in that: the device comprises a mixed acid feeding pipeline (1), a nitrobenzene feeding pipeline (2), a micro mixer (3), a micro reactor (4), a time-delay reactor (5) and a post-processing system (6), wherein the micro mixer (3) is provided with a first feeding channel (311) and a second feeding channel (312), the mixed acid feeding pipeline (1) is connected with the first feeding channel (311), the nitrobenzene feeding pipeline (2) is connected with the second feeding channel (312), a first metering pump (101) is arranged on the mixed acid feeding pipeline (1), a second metering pump (201) is arranged on the nitrobenzene feeding pipeline (2), and the micro mixer (3), the micro reactor (4), the time-delay reactor (5) and the post-processing system (6) are sequentially connected in series; the micro mixer (3) comprises a micro mixer substrate (31) and first heat exchange plates (32) arranged on two sides of the micro mixer substrate (31), a first dispersion mixing unit group (315) is arranged in the micro mixer substrate (31), the micro reactor (4) comprises a micro reactor substrate (41) and second heat exchange plates arranged on two sides of the micro reactor substrate (41), and a second dispersion unit group (413) is arranged in the micro reactor substrate (41).
2. The apparatus for the continuous synthesis of mixed dinitrobenzene with high selectivity according to claim 1, wherein: be equipped with first pan feeding passageway (311), second pan feeding passageway (312), discharging channel (313), first dispersion mixing unit group (315) and first connecting channel (316) in micromixer base plate (31), wherein each first dispersion mixing unit group (315) establishes ties in proper order through corresponding first connecting channel (316) respectively, and the first dispersion mixing unit group (315) pan feeding end that is located the input side is equipped with mixed interface runner (314) of taking two venturi type undergauge passageways, just first pan feeding passageway (311) and second pan feeding passageway (312) respectively with the venturi type undergauge passageway that corresponds on mixed interface runner (314) is connected, first dispersion mixing unit group (315) the discharge end that is located the output side with discharging channel (313) are connected.
3. The apparatus for the continuous synthesis of mixed dinitrobenzene with high selectivity according to claim 1, wherein: the micro-reactor base plate (41) is internally provided with a reaction feeding channel (411), a reaction discharging channel (412), a second dispersion mixing unit group (413) and a second connecting channel (414), wherein each second dispersion unit group (413) is sequentially connected in series through the corresponding second connecting channel (414), the input end of the second dispersion mixing unit group (413) positioned at the input side is connected with the reaction feeding channel (411), and the output end of the second dispersion mixing unit group (413) positioned at the output side is connected with the reaction discharging channel (412).
4. The apparatus for the continuous synthesis of mixed dinitrobenzene with high selectivity according to claim 1, wherein: the first dispersing and mixing unit group (315) comprises a plurality of first dispersing and mixing units (3151) which are sequentially connected in series, the second dispersing and mixing unit group (413) comprises a plurality of second dispersing and mixing units (4131) which are sequentially connected in series, and the first dispersing and mixing units (3151) and the second dispersing and mixing units (4131) have the same structure and respectively comprise dispersing flow channels (317) and converging flow channels (318).
5. The apparatus for the continuous synthesis of mixed dinitrobenzene with high selectivity according to claim 1, wherein: the heat exchange plate comprises a first heat exchange plate (32), a second heat exchange plate and a connecting flow channel section (324), wherein the first heat exchange plate and the second heat exchange plate are identical in structure, a heat exchange medium input flow channel (321), a heat exchange medium output flow channel (322), a bending flow channel section (323) and the connecting flow channel section (324) are arranged inside the first heat exchange plate and the second heat exchange plate, the bending flow channel sections (323) are sequentially connected in series through the corresponding connecting flow channel sections (324), the input end of the bending flow channel section (323) at the input side is connected with the heat exchange medium input flow channel (321), and the output end of the bending flow channel section (323) at the output side is connected with the heat exchange medium output flow channel (322).
6. The apparatus for the continuous synthesis of mixed dinitrobenzene with high selectivity according to claim 1, wherein: the number of the microreactors (4) is at least one, and the number of the time-delay reactors (5) is at least one.
7. The apparatus for the continuous synthesis of mixed dinitrobenzene with high selectivity according to claim 1, wherein: the post-treatment system (6) comprises a waste acid and nitration product separator, a prewashing device, a prewashing separator, an alkali washing device, an alkali washing separator, a water washing device and a water washing separator which are sequentially connected in series.
8. A method for high-selectivity continuous synthesis of mixed dinitrobenzene according to claim 1, wherein: the method comprises the following steps:
step one, preparing a mixed acid solution of nitric acid and sulfuric acid;
pumping mixed acid into the micro mixer (3) through a first metering pump (101), pumping nitrobenzene into the micro mixer (3) through a second metering pump (201), and controlling the pumping rate of the first metering pump (101) and the second metering pump (201) to control the molar ratio of nitrobenzene to nitric acid to sulfuric acid;
step three, controlling the temperature of the first heat exchange plate (32) and the second heat exchange plate to be 60-80 ℃, controlling the total residence time of reaction materials in the micro mixer (3), the micro reactor (4) and the time delay reactor (5) to be 150-600 seconds, mixing and contacting two streams of raw material liquid of nitrobenzene and mixed acid in the micro mixer (3), and reacting in the micro reactor (4), wherein the reaction formula is as follows:
step four: the reaction materials are output from the time delay reactor (5) and enter a post-treatment system (6) and are separated to obtain target products.
9. The method for the high-selectivity continuous synthesis of mixed dinitrobenzene according to claim 8, wherein: in the first step, the mixed acid is prepared from nitric acid, sulfuric acid and water, the mass concentration of the water in the mixed acid is 3% -15%, the nitric acid is fuming nitric acid with the concentration of more than 98%, the sulfuric acid is concentrated sulfuric acid with the concentration of more than 98%, and the temperature of the process of preparing the mixed acid is controlled to be below 40 ℃.
10. The method for the high-selectivity continuous synthesis of mixed dinitrobenzene according to claim 8, wherein: in the second step, the molar ratio of the materials is controlled as nitrobenzene: nitric acid: sulfuric acid 1: (1.05-1.25): (1.5-2.3), the flowing pressure of the nitrobenzene and the mixed acid in the microchannel reactor is 0-1 MPa.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115043767A (en) * | 2022-07-15 | 2022-09-13 | 睦化(上海)流体工程有限公司 | Microchannel reaction process and device for preparing benzoyl peroxide |
| CN115160203A (en) * | 2022-07-15 | 2022-10-11 | 睦化(上海)流体工程有限公司 | Continuous compounding method and device for benzoyl peroxide product |
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