A catalyst, a preparation method thereof and a process for producing 3,4-dichloronitrobenzene without waste water

Abstract

The present application relates to the technical fields of chemical synthesis, and discloses a kind of catalyst and preparation method and the process method of wastewater-free production 3,4-dichloronitrobenzene, wherein the process method of wastewater-free production 3,4-dichloronitrobenzene includes the following steps: (1) adding self-dehydration type solid acid catalyst to primary chlorination tower, secondary chlorination tower, tertiary chlorination tower;(2) the p-chloronitrobenzene raw material is sequentially transported to primary chlorination tower, secondary chlorination tower, tertiary chlorination tower and is introduced into chlorine gas to carry out chlorination reaction, the generated hydrogen chloride gas and unreacted chlorine gas escape from tower top, enter exhaust gas main pipeline, and the chlorinated liquid of reaction is sequentially transported to primary deacidification kettle and secondary deacidification kettle to carry out deacidification treatment;(3) hydrogen chloride gas and unreacted chlorine gas in exhaust gas main pipeline are discharged after treatment reaches standard;(4) deacidification chlorinated liquid is sequentially treated by light removal tower and heavy removal tower, crystallization purification, and 3,4-dichloronitrobenzene is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical synthesis, more particularly, to a kind of catalyst and its preparation method and the process method of producing 3,4-dichloronitrobenzene without waste water. BACKGROUND

[0002] There are mainly two routes for producing 3,4-dichloronitrobenzene by chlorination method, p-chloronitrobenzene chlorination method and o-dichlorobenzene nitration method. The p-chloronitrobenzene chlorination method mostly adopts intermittent kettle chlorination. Under the action of anhydrous ferric chloride catalyst, melt state p-chloronitrobenzene is added into a porcelain reaction kettle, chlorine gas is introduced, the chlorination reaction temperature is controlled at 100-110℃, and the reaction is carried out for 8-9 hours to generate 3,4-dichloronitrobenzene. After the refining process, the product is obtained. The o-dichlorobenzene nitration method has several nitration processes, such as kettle type continuous, pipe type continuous and adiabatic nitration. The mixed acid of o-dichlorobenzene, nitric acid and sulfuric acid is introduced into a reactor to carry out nitration reaction to generate about 90% of 3,4-dichloronitrobenzene and about 10% of 2,3-dichloronitrobenzene. 3,4-dichloronitrobenzene is refined as a product, and the mixture of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene is sold or further processed.

[0003] At present, the existing p-chloronitrobenzene chlorination method adopts a bubbling mode. The materials in the kettle are not uniformly mixed, there is a certain temperature difference between the kettle wall and the kettle, a small amount of polychloride is generated due to excessive chlorination, and part of the chlorine gas has not reacted yet and escapes, causing waste. The raw material unit consumption of the product is high, and the product quality is poor. At the same time, due to the limited heat exchange area of the reactor jacket, it is difficult to remove the generated reaction heat in time, resulting in low production capacity and equipment efficiency. And because the residence time of chlorine gas in the kettle is extremely short, a large amount of anhydrous ferric chloride must be added as a catalyst to ensure the normal chlorination, and the compounds generated by the side reaction will adhere to the surface of the catalyst. The removal process of ferric chloride needs to use water washing, which will produce a large amount of waste water, and seriously increase the production and maintenance cost. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a process method for producing 3,4-dichloronitrobenzene without waste water.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A kind of catalyst for producing 3,4-dichloronitrobenzene without waste water, the raw materials include the following components by weight fraction:

[0007] Mesoporous silica 100~120 parts, active alumina 20~30 parts, graphene modified carbon nanotube 5~15 parts, vinyl tri (β-methoxyethoxy) silane 3~8 parts, ferric chloride 15~25 parts, titanium tetrachloride 10~20 parts, copper chloride 6~10 parts, phosphotungstic acid 8~16 parts, 3A molecular sieve 30~50 parts, anhydrous calcium sulfate 10~20 parts, magnesium oxide 3~5 parts, calcium oxide 3~5 parts, bentonite 10~12 parts, polyvinyl alcohol 4~8 parts, ammonium bicarbonate 3~5 parts, anhydrous ethanol 300~500 parts, N-methyl pyrrolidone 40~60 parts, deionized water 20~30 parts.

[0008] Further, the preparation method of the catalyst comprises the following steps:

[0009] S1, respectively weighing each raw material component by weight fraction;

[0010] S2, adding vinyl tri (β-methoxyethoxy) silane to 1 / 2 of anhydrous ethanol, stirring uniformly, then adding mesoporous silica and active alumina, ball milling at a speed of 200~300 rpm for 2~4 h, drying in an oven at a temperature of 120~150 ℃, then calcining in a calcining furnace at a temperature of 350~400 ℃ for 3~5 h, and cooling at room temperature to obtain a pretreated carrier;

[0011] S3, adding graphene modified carbon nanotube to N-methyl pyrrolidone, ultrasonic dispersing at a power of 300~500 W for 30~60 min, then adding the pretreated carrier to mix, stirring and mixing at a speed of 400~600 rpm at a temperature of 80~100 ℃ for 10~20 h, and distilling under reduced pressure to obtain a carbon material composite carrier;

[0012] S4, adding ferric chloride, titanium tetrachloride, copper chloride and phosphotungstic acid to the remaining 1 / 2 of anhydrous ethanol, ultrasonic dispersing at a power of 400~600 W for 20~40 min to obtain an impregnation solution;

[0013] S5, placing the carbon material composite carrier in the impregnation solution for impregnation three times, each time after impregnation, stepwise drying, the first time at a temperature of 60~80 ℃ for 2~4 h, the second time at a temperature of 70~90 ℃ for 2~4 h after drying, and the third time at a temperature of 80~100 ℃ for 1~2 h after drying, to obtain a catalyst precursor;

[0014] S6, placing 3A molecular sieve in a calcining furnace to calcine and activate at 350~400 ℃ for 3~5 h, uniformly mixing with anhydrous calcium sulfate, magnesium oxide, calcium oxide and bentonite after cooling at room temperature, placing in a kneader, then sequentially adding polyvinyl alcohol, ammonium bicarbonate, carbon material composite carrier and deionized water, kneading at room temperature for 30~60 min, and extruding to form particles with a diameter of 3~5 mm and a length of 5~10 mm.

[0015] S7, the particles are placed in a fluidized bed reactor, nitrogen is introduced for protection, the temperature is raised to 200-250℃ at a rate of 2-3℃ / min, switched to hydrogen chloride-chlorine mixed gas, the volume ratio of hydrogen chloride to chlorine is 1:1-3, activated for 6-12h, then nitrogen is introduced and the temperature is lowered to 150-180℃, kept for 2-4h, cooled at room temperature, to obtain a self-dehydrated solid acid catalyst;

[0016] The preparation method of the graphene modified carbon nanotube in step S1 comprises the following steps:

[0017] A1, according to the weight fraction, respectively, 100-120 parts of graphene oxide dispersion liquid with a concentration of 1-5mg / mL, 10-30 parts of hydroxylated multi-walled carbon nanotubes, 5-15 parts of hydrazine hydrate;

[0018] A2, the hydroxylated multi-walled carbon nanotubes are added to the graphene oxide dispersion liquid, ultrasonic dispersion is carried out at a power of 400-600W for 30-60min, and a mixed suspension is obtained;

[0019] A3, the mixed suspension is placed in a reaction kettle, hydrothermal reaction is carried out at a temperature of 120-180℃ for 12-18h, the temperature is lowered to 60-80℃ and hydrazine hydrate is added, the reduction reaction is continued for 4-6h, and freeze-drying is carried out, to obtain graphene modified carbon nanotubes.

[0020] Further, a process for producing 3,4-dichloronitrobenzene without waste water, comprising the following steps:

[0021] (1) adding a catalyst into the first-stage chlorination tower, the second-stage chlorination tower and the third-stage chlorination tower;

[0022] (2) feeding p-chloronitrobenzene raw material from the top of the first-stage chlorination tower into the tower and flowing to the bottom of the tower, and bubbling chlorine gas from the bottom of the first-stage chlorination tower into the tower and flowing to the top of the tower for chlorination reaction, the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top of the tower enter the tail gas main pipeline;

[0023] (3) the chlorination liquid overflow of the first-stage chlorination tower enters the top of the second-stage chlorination tower and flows to the bottom of the tower, chlorine gas is bubbled from the bottom of the second-stage chlorination tower into the tower and flows to the top of the tower for chlorination reaction, the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top of the tower enter the tail gas main pipeline;

[0024] (4) the chlorination liquid overflow of the second-stage chlorination tower enters the top of the third-stage chlorination tower and flows to the bottom of the tower, chlorine gas is bubbled from the bottom of the third-stage chlorination tower into the tower and flows to the top of the tower for chlorination reaction, the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top of the tower enter the tail gas main pipeline, and the chlorination liquid overflows from the third-stage tower to the buffer tank.

[0025] (5) The hydrogen chloride gas and unreacted chlorine gas in the tail gas main pipeline are first removed of organic matter by a trap, then cooled to 20-40℃ by a cooler, and the condensed p-nitrochlorobenzene and 3,4-dichloronitrobenzene are recovered, the condensed gas is then introduced into a filter to remove solid particles, and the purified gas is introduced into a three-stage falling film absorber to generate 30%-32% industrial hydrochloric acid by absorption with desalted water, the remaining gas after the absorption treatment with desalted water is introduced into a two-stage alkali absorption tower, and a 5%-10% NaOH solution is used for absorption reaction to generate 8%-10% sodium hypochlorite solution, and finally the gas is discharged after being adsorbed by activated carbon;

[0026] (6) The chlorination liquid in the buffer tank is transported to a first deacidification kettle, and compressed air is introduced to bubble to remove hydrogen chloride at a temperature of 90-100℃, the chlorination liquid in the first deacidification kettle is overflowed into a second deacidification kettle, and compressed air is further introduced to bubble to remove hydrogen chloride at a temperature of 100-110℃, and the deacidified chlorination liquid is introduced into a crude product tank;

[0027] (7) The chlorination liquid in the crude product tank is transported to a light component removal tower, the kettle temperature of the light component removal tower is controlled to be 170-180℃, and the overhead temperature is controlled to be 160-170℃, p-chloronitrobenzene is evaporated from the top of the tower to be recovered and reused, the kettle material is introduced into a heavy component removal tower, the kettle temperature of the heavy component removal tower is controlled to be 185-195℃, and the overhead temperature is controlled to be 175-185℃, tar is collected from the kettle of the heavy component removal tower, and the overhead material is crystallized and purified to obtain 3,4-dichloronitrobenzene;

[0028] The catalyst is a self-dehydrated solid acid catalyst prepared by the preparation method of claim 2.

[0029] Further, the loading amount of the self-dehydrated solid acid catalyst in the first-stage chlorination tower, the second-stage chlorination tower and the third-stage chlorination tower in step (1) is 30%-50% of the volume of each chlorination tower.

[0030] Further, the temperature of the first-stage chlorination tower in step (2) is 60-80℃, the pressure is -5--1 Kpa, and the flow rate of chlorine gas in the first-stage chlorination tower is 0.3-0.6 t / h.

[0031] Further, the temperature of the second-stage chlorination tower in step (3) is 70-90℃, the pressure is -5--1 Kpa, and the flow rate of chlorine gas in the second-stage chlorination tower is 0.2-0.4 t / h.

[0032] Further, the temperature of the third-stage chlorination tower in step (4) is 80-100℃, the pressure is -5--1 Kpa, and the flow rate of chlorine gas in the third-stage chlorination tower is 0.1-0.2 t / h.

[0033] Further, the mass fraction of the industrial hydrochloric acid in the step (5) is 30-32%, the mass fraction of the NaOH solution is 5-10%, and the mass fraction of the sodium hypochlorite solution is 8-10%.

[0034] Further, the flow rate of the chlorination liquid in the buffer tank to the primary deacidification kettle in the step (6) is 2-4 t / h.

[0035] Further, the flow rate of the chlorination liquid in the crude product tank to the light-removing tower in the step (7) is 2.5-4.5 t / h, and the flow rate of the kettle material into the heavy-removing tower is 1.5-3 t / h.

[0036] In summary, the present application at least has the following beneficial effects:

[0037] (1) The present application uses carbon material composite carriers to load metal chlorides with multiple active sites to prepare a self-dehydration type solid acid catalyst, the catalyst itself has water absorption capacity, and the trace water generated in the reaction is captured by molecular sieves and calcium sulfate in time, so that water is avoided to participate in the side reaction, hydrogen chloride dissolution loss is reduced, and a water-free environment of the reaction system is maintained. The Lewis acid site (metal chloride) on the catalyst dominates the chlorination reaction, while the Bronsted acid site (phosphotungstic acid) preferentially promotes the generation of 3,4-isomer, and the dual-function synergistically improves the selectivity of 3,4-isomer; and the dehydration component on the catalyst maintains structural stability in a water-containing atmosphere, avoids the loss of metal chlorides, and at the same time, the dehydration component can be regenerated in situ at 250-300 DEG C, while the active component metal chlorides can be periodically activated in a chlorine atmosphere, so that the whole life cycle of the catalyst is free of wastewater treatment.

[0038] (2) This invention, by adding graphene-modified carbon nanotubes, gives the self-dehydrating solid acid catalyst a three-dimensional network structure. Graphene has a two-dimensional planar structure, while carbon nanotubes have a one-dimensional linear structure. The two intertwine to form a stable, porous three-dimensional network framework, which provides a huge specific surface area and firm anchoring points for the subsequently loaded metal chloride active centers. The strong adsorption effect firmly fixes the volatile or soluble metal chloride active components, especially in the reaction environment containing chlorine and hydrogen chloride, greatly extending the catalyst life. At the same time, the three-dimensional network gives the catalyst particles extremely high mechanical strength, which can withstand the long-term flow and scouring of materials in the chlorination tower, reducing pulverization and lowering the system pressure drop. Furthermore, both graphene and carbon nanotubes are thermal conductors. The three-dimensional network they form can form a micro-circulation heat dissipation system inside the catalyst, thereby eliminating local hot spots. Chlorination is an exothermic reaction, and traditional catalysts, due to their poor thermal conductivity, are prone to forming local high temperatures, leading to over-chlorination, carbon deposition, and catalyst sintering and deactivation. The graphene-carbon nanotube network can quickly dissipate the heat of reaction, making the temperature distribution of the catalyst bed uniform. A uniform temperature field facilitates the reaction towards the target product, suppressing side reactions and effectively improving selectivity. The three-dimensional network structure also possesses richly layered channels, providing high-speed pathways for the diffusion of reactants and products, reducing internal diffusion resistance. Reactants can more quickly contact the internal active sites, and products can rapidly exit, thereby improving the intrinsic reaction rate and catalyst utilization. Simultaneously, the abundant channels provide ample space and contact interfaces for the dehydrating components, facilitating efficient capture of reaction-generated water and enhancing self-dehydration. The defects and edge sites of graphene and carbon nanotubes themselves can serve as Lewis acid sites, or synergistically interact with supported phosphotungstic acid (Brønsted acid), modulating the electronic effects on the catalyst surface and controlling the reaction pathway at the electronic level, further enhancing the selectivity for the 3,4-position chlorination reaction.

[0039] (3) This invention employs a multi-stage chlorination tower with graded chlorine feeding and circulating stirring. The tower has a large height-to-diameter ratio, allowing chlorine to remain in the tower for a long time during its ascent. The chlorination tower is filled with pre-packed catalyst, which generates more turbulence, effectively improving gas-liquid contact and thus increasing reaction efficiency, reducing side reactions, and lowering chlorine consumption. This, in turn, improves material selectivity, conversion rate, and product quality. Furthermore, due to the large height-to-diameter ratio of the chlorination tower, it has excellent mass and heat transfer, allowing for stable temperature control. The chlorination reaction does not require the addition of large amounts of ferric chloride catalyst to ensure chlorination efficiency; instead, a self-dehydrating solid acid catalyst is used. This not only extends the catalyst's lifespan but also reduces waste generation. The 3,4-dichloronitrobenzene production process provided by this invention uses readily available raw materials, is simple to operate, is suitable for continuous industrial production, and produces high-purity products. Attached Figure Description

[0040] Figure 1 System flow chart for the production process of 3,4-dichloronitrobenzene of the present application;

[0041] Figure 2 Liquid chromatogram of 3,4-dichloronitrobenzene prepared for Example 1 of the present application;

[0042] Figure 3 Liquid chromatogram of 3,4-dichloronitrobenzene prepared for Example 2 of the present application;

[0043] Figure 4 Liquid chromatogram of 3,4-dichloronitrobenzene prepared for Example 3 of the present application. DETAILED DESCRIPTION

[0044] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] It should be noted that, unless otherwise specified, all the technical and scientific terms used in the present application have the same meaning as that generally understood by the ordinary skilled in the art to which the present application belongs.

[0046] As shown in Figure 1 The present application provides a process for producing 3,4-dichloronitrobenzene without wastewater, comprising the following steps:

[0047] A process for producing 3,4-dichloronitrobenzene without wastewater, comprising the following steps:

[0048] (1) 100-120 parts of graphene oxide dispersion solution with a concentration of 1-5 mg / mL, 10-30 parts of hydroxylated multi-walled carbon nanotubes, and 5-15 parts of hydrazine hydrate are weighed according to the weight fraction;

[0049] (2) The hydroxylated multi-walled carbon nanotubes are added to the graphene oxide dispersion solution, and ultrasonic dispersion is carried out at a power of 400-600 W for 30-60 min to obtain a mixed suspension;

[0050] (3) The mixed suspension is placed in a reaction kettle and subjected to hydrothermal reaction at a temperature of 120-180℃ for 12-18 h, cooled to 60-80℃ and hydrazine hydrate is added, and the reduction reaction is continued for 4-6 h, and freeze-drying is carried out to obtain graphene modified carbon nanotubes;

[0051] (4) mesoporous silica 100-120 parts, activated alumina 20-30 parts, graphene modified carbon nanotube 5-15 parts, vinyl tri(β-methoxyethoxy) silane 3-8 parts, ferric chloride 15-25 parts, titanium tetrachloride 10-20 parts, copper chloride 6-10 parts, phosphotungstic acid 8-16 parts, 3A molecular sieve 30-50 parts, anhydrous calcium sulfate 10-20 parts, magnesium oxide 3-5 parts, calcium oxide 3-5 parts, bentonite 10-12 parts, polyvinyl alcohol 4-8 parts, ammonium bicarbonate 3-5 parts, anhydrous ethanol 300-500 parts, N-methyl pyrrolidone 40-60 parts, deionized water 20-30 parts by weight;

[0052] (5) the vinyl tri(β-methoxyethoxy) silane is added to 1 / 2 of the anhydrous ethanol, stirred uniformly, then the mesoporous silica and activated alumina are added, and ball milling is carried out at a speed of 200-300 rpm for 2-4 h, then the mixture is dried in an oven at a temperature of 120-150℃, and then the mixture is calcined in a calcining furnace at a temperature of 350-400℃ for 3-5 h, and then the mixture is cooled at room temperature to obtain a pretreated carrier;

[0053] (6) the graphene modified carbon nanotube is added to N-methyl pyrrolidone, ultrasonically dispersed at a power of 300-500 W for 30-60 min, then the pretreated carrier is added and mixed, and then stirring and mixing are carried out at a speed of 400-600 rpm at a temperature of 80-100℃ for 10-20 h, and then the mixture is distilled under reduced pressure to obtain a carbon material composite carrier;

[0054] (7) the ferric chloride, titanium tetrachloride, copper chloride and phosphotungstic acid are added to the remaining 1 / 2 of the anhydrous ethanol, and ultrasonically dispersed at a power of 400-600 W for 20-40 min to obtain an impregnation solution;

[0055] (8) the carbon material composite carrier is immersed in the impregnation solution for three times, and after each immersion, the mixture is dried in stages, the first time at a temperature of 60-80℃ for 2-4 h, the second time at a temperature of 70-90℃ for 2-4 h after drying, and the third time at a temperature of 80-100℃ for 1-2 h after drying, to obtain a catalyst precursor;

[0056] (9) the 3A molecular sieve is calcined in a calcining furnace at a temperature of 350-400℃ for 3-5 h, and then the mixture is cooled at room temperature, and then the mixture is uniformly mixed with the anhydrous calcium sulfate, magnesium oxide, calcium oxide and bentonite, and then the mixture is placed in a kneader, and then the polyvinyl alcohol, ammonium bicarbonate, carbon material composite carrier and deionized water are sequentially added, and then the mixture is kneaded at room temperature for 30-60 min, and then the mixture is extruded to form a particle with a diameter of 3-5 mm and a length of 5-10 mm;

[0057] (10) Put the particles into the fluidized bed reactor, and protect with nitrogen. Increase the temperature to 200-250℃ at a rate of 2-3℃ / min, switch to hydrogen chloride-chlorine mixed gas, wherein the volume ratio of hydrogen chloride to chlorine is 1:1-3, and activate for 6-12h. Then, pass nitrogen and decrease the temperature to 150-180℃, and keep the temperature for 2-4h. Cool at room temperature to obtain the self-dehydrated solid acid catalyst;

[0058] (11) Add the self-dehydrated solid acid catalyst to the first, second and third chlorination towers, and the loading amount of the catalyst is 30%-50% of the volume of the chlorination tower;

[0059] (12) Deliver the p-chloronitrobenzene raw material from the top of the first chlorination tower into the tower and flow to the bottom of the tower. Deliver the chlorine gas from the bottom of the first chlorination tower into the tower at a flow rate of 0.3-0.6t / h and flow to the top of the tower. Control the temperature of the first chlorination tower to be 60-80℃, and the pressure to be -5--1Kpa to carry out the chlorination reaction. The generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0060] (13) The chlorination liquid overflow of the first chlorination tower enters the top of the second chlorination tower and flows to the bottom of the tower. Deliver the chlorine gas from the bottom of the second chlorination tower into the tower at a flow rate of 0.2-0.4t / h and flow to the top of the tower. Control the temperature of the second chlorination tower to be 70-90℃, and the pressure to be -5--1Kpa to carry out the chlorination reaction. The generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0061] (14) The chlorination liquid overflow of the second chlorination tower enters the top of the third chlorination tower and flows to the bottom of the tower. Deliver the chlorine gas from the bottom of the third chlorination tower into the tower at a flow rate of 0.1-0.2t / h and flow to the top of the tower. Control the temperature of the third chlorination tower to be 80-100℃, and the pressure to be -5--1Kpa to carry out the chlorination reaction. The generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline. The chlorination liquid overflows from the third tower to the buffer tank;

[0062] (15) The hydrogen chloride gas and unreacted chlorine gas in the tail gas main pipeline first pass through the trap to remove organic matter, and then pass through the cooler to be cooled to 20-40℃. Condense and recover the p-nitrochlorobenzene and 3,4-dichloronitrobenzene. The condensed gas enters the filter to remove solid particles. The purified gas enters the three-stage falling film absorber to generate industrial hydrochloric acid with a mass fraction of 30%-32% by absorbing with desalted water. The remaining gas enters the two-stage alkali absorption tower to generate sodium hypochlorite solution with a mass fraction of 8%-10% by absorbing with NaOH solution with a mass fraction of 5%-10%. Finally, the gas is discharged after being adsorbed by activated carbon;

[0063] (16) The chlorinated liquid in the buffer tank is transported to the first deacidification kettle at a flow rate of 2-4 t / h, and compressed air is introduced to bubble and remove hydrogen chloride at a temperature of 90-100 DEG C. The chlorinated liquid in the first deacidification kettle overflows into the second deacidification kettle, and compressed air is further introduced to remove hydrogen chloride at a temperature of 100-110 DEG C. The deacidified chlorinated liquid enters the crude product tank;

[0064] (17) The chlorinated liquid in the crude product tank is transported to the light component removal column at a flow rate of 2.5-4.5 t / h, the column kettle temperature of the light component removal column is controlled at 170-180 DEG C, the overhead temperature is controlled at 160-170 DEG C, and p-chloronitrobenzene is evaporated from the top of the column to be recycled. The column kettle material enters the heavy component removal column at a flow rate of 1.5-3 t / h, the column kettle temperature of the heavy component removal column is controlled at 185-195 DEG C, the overhead temperature is controlled at 175-185 DEG C, and tar is collected from the column kettle. The overhead material is crystallized and purified to obtain 3,4-dichloronitrobenzene.

[0065] The technical solutions provided by the present application are described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.

[0066] Example 1

[0067] The process for producing 3,4-dichloronitrobenzene without wastewater in this example comprises the following steps:

[0068] (1) 100 parts of graphene oxide dispersion liquid with a concentration of 1 mg / mL, 10 parts of hydroxylated multi-walled carbon nanotubes, and 5 parts of hydrazine hydrate are weighed according to the weight fraction;

[0069] (2) The hydroxylated multi-walled carbon nanotubes are added to the graphene oxide dispersion liquid, and ultrasonic dispersion is performed at a power of 400 W for 30 min to obtain a mixed suspension;

[0070] (3) The mixed suspension is placed in a reaction kettle and subjected to hydrothermal reaction at a temperature of 120 DEG C for 12 h. After cooling to 60 DEG C, hydrazine hydrate is added, and the reduction reaction is continued for 4 h. After freeze-drying, graphene modified carbon nanotubes are obtained;

[0071] (4) 100 parts of mesoporous silica, 20 parts of active alumina, 5 parts of graphene modified carbon nanotubes, 3 parts of vinyl tri(β-methoxyethoxy)silane, 15 parts of ferric chloride, 10 parts of titanium tetrachloride, 6 parts of copper chloride, 8 parts of phosphotungstic acid, 30 parts of 3A molecular sieve, 10 parts of anhydrous calcium sulfate, 3 parts of magnesium oxide, 3 parts of calcium oxide, 10 parts of bentonite, 4 parts of polyvinyl alcohol, 3 parts of ammonium bicarbonate, 300 parts of anhydrous ethanol, 40 parts of N-methyl pyrrolidone, and 20 parts of deionized water are weighed according to the weight fraction;

[0072] (5) the vinyl tri (β-methoxyethoxy) silane is added into 1 / 2 of anhydrous ethanol, stirred uniformly, then mesoporous silica, activated alumina are added, ball-milling mixed for 2 hours at a speed of 200 rpm, placed in an oven to dry at a temperature of 120℃, then placed in a calcining furnace to calcine at a temperature of 350℃ for 3 hours, cooled at room temperature, to obtain a pretreated carrier;

[0073] (6) the graphene modified carbon nanotube is added into N-methyl pyrrolidone, ultrasonically dispersed for 30 minutes at a power of 300W, then mixed with the pretreated carrier, stirred and mixed at a speed of 400 rpm at a temperature of 80℃ for 10 hours, distilled under reduced pressure, to obtain a carbon material composite carrier;

[0074] (7) the ferric chloride, titanium tetrachloride, copper chloride, phosphotungstic acid are added into the remaining 1 / 2 of anhydrous ethanol, ultrasonically dispersed for 20 minutes at a power of 400W, to obtain an impregnation solution;

[0075] (8) the carbon material composite carrier is immersed in the impregnation solution for three times, each time after immersion, stepwise drying, the first time at a temperature of 60℃ for 2 hours, after drying, the second time at a temperature of 70℃ for 2 hours, after drying, the third time at a temperature of 80℃ for 1 hour, to obtain a catalyst precursor;

[0076] (9) the 3A molecular sieve is placed in a calcining furnace to calcine and activate at 350℃ for 3 hours, after cooling at room temperature, mixed uniformly with anhydrous calcium sulfate, magnesium oxide, calcium oxide, bentonite, placed in a kneader, then polyvinyl alcohol, ammonium bicarbonate, carbon material composite carrier and deionized water are added in sequence, kneaded at room temperature for 30 minutes, extruded into particles with a diameter of 3mm and a length of 5mm;

[0077] (10) the particles are placed in a fluidized bed reactor, nitrogen is introduced for protection, heated to 200℃ at a rate of 2℃ / min, switched to hydrogen chloride-chlorine mixed gas, the volume ratio of hydrogen chloride to chlorine is 1:1, heated to 250℃ and activated for 6 hours, then nitrogen is introduced and the temperature is lowered to 150℃, kept for 2 hours, cooled at room temperature, to obtain a self-dehydration type solid acid catalyst;

[0078] (11) the self-dehydration type solid acid catalyst is added to the first chlorination tower, the second chlorination tower and the third chlorination tower, the loading amount of the catalyst is 30% of the volume of the chlorination tower;

[0079] (12) the p-chloronitrobenzene raw material is transported from the top of the first chlorination tower to the tower and flows to the bottom of the tower, chlorine gas is bubbled from the bottom of the first chlorination tower to the tower at a flow rate of 0.3t / h and flows to the top of the tower, the temperature of the first chlorination tower is controlled at 60℃, the pressure is -1Kpa, and the chlorination reaction is carried out, the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0080] (13) The chlorination liquid overflow of the first-stage chlorination tower enters the top of the second-stage chlorination tower and flows to the bottom, and chlorine gas is bubbled into the tower from the bottom of the second-stage chlorination tower at a flow rate of 0.2 t / h and flows to the top of the tower, the temperature of the second-stage chlorination tower is controlled at 70℃, and the pressure is -1 Kpa, and the chlorination reaction is carried out, the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0081] (14) The chlorination liquid overflow of the second-stage chlorination tower enters the top of the third-stage chlorination tower and flows to the bottom, and chlorine gas is bubbled into the tower from the bottom of the third-stage chlorination tower at a flow rate of 0.1 t / h and flows to the top of the tower, the temperature of the third-stage chlorination tower is controlled at 80℃, and the pressure is -1 Kpa, and the chlorination reaction is carried out, the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline, and the chlorination liquid overflows from the third-stage tower to the buffer tank;

[0082] (15) The hydrogen chloride gas and unreacted chlorine gas in the tail gas main pipeline first pass through a trap to remove organic matter, and then pass through a cooler to be cooled to 20℃, and p-nitrochlorobenzene and 3,4-dichloronitrobenzene are condensed and recovered, the condensed gas enters a filter to remove solid particles, and the purified gas enters a three-stage falling film absorber to generate industrial hydrochloric acid with a mass fraction of 30% by absorbing with desalted water, and the remaining gas enters a two-stage alkali absorption tower to generate sodium hypochlorite solution with a mass fraction of 8% by absorbing with NaOH solution with a mass fraction of 5%, and finally the gas is discharged after being adsorbed by activated carbon;

[0083] (16) The chlorination liquid in the buffer tank is transported to the first-stage deacidification kettle at a flow rate of 2 t / h, and compressed air is introduced to bubble and remove hydrogen chloride at a temperature of 90℃, the chlorination liquid in the first-stage deacidification kettle overflows into the second-stage deacidification kettle, and compressed air is further introduced to bubble and remove hydrogen chloride at a temperature of 100℃, and the deacidified chlorination liquid enters the crude product tank;

[0084] (17) The chlorination liquid in the crude product tank is transported to the light component removal tower at a flow rate of 2.5 t / h, the kettle temperature of the light component removal tower is controlled at 170℃, and the top temperature is controlled at 160℃, p-chloronitrobenzene is distilled out of the top of the tower and recovered for reuse, and the kettle material enters the heavy component removal tower at a flow rate of 1.5 t / h, the kettle temperature of the heavy component removal tower is controlled at 185℃, and the top temperature is controlled at 175℃, and tar is collected from the kettle, and the top material is crystallized and purified to obtain 3,4-dichloronitrobenzene.

[0085] The 3,4-dichloronitrobenzene prepared in Example 1 is detected by a liquid chromatograph, and the specific results are shown in Table 1. Figure 2

[0086] Example 2

[0087] The process method for producing 3,4-dichloronitrobenzene without waste water in this example comprises the following steps:

[0088] ​(1) 110 parts of graphene oxide dispersion solution with a concentration of 3 mg / mL, 20 parts of hydroxylated multi-walled carbon nanotubes, and 10 parts of hydrazine hydrate are weighed according to weight fraction;

[0089] (2) The hydroxylated multi-walled carbon nanotubes are added to the graphene oxide dispersion solution, and ultrasonic dispersion is performed at a power of 500 W for 45 min to obtain a mixed suspension;

[0090] (3) The mixed suspension is placed in a reaction kettle, and hydrothermal reaction is performed at a temperature of 150℃ for 15 h. After cooling to 70℃, hydrazine hydrate is added, and the reduction reaction is continued for 5 h. After freeze-drying, graphene modified carbon nanotubes are obtained;

[0091] (4) 110 parts of mesoporous silica, 25 parts of active alumina, 10 parts of graphene modified carbon nanotubes, 5 parts of vinyl tri(β-methoxyethoxy) silane, 20 parts of ferric chloride, 15 parts of titanium tetrachloride, 8 parts of copper chloride, 12 parts of phosphotungstic acid, 40 parts of 3A molecular sieve, 15 parts of anhydrous calcium sulfate, 4 parts of magnesium oxide, 4 parts of calcium oxide, 11 parts of bentonite, 6 parts of polyvinyl alcohol, 4 parts of ammonium bicarbonate, 400 parts of anhydrous ethanol, 50 parts of N-methyl pyrrolidone, and 25 parts of deionized water are weighed according to weight fraction;

[0092] (5) The vinyl tri(β-methoxyethoxy) silane is added to 1 / 2 of the anhydrous ethanol, stirred uniformly, and then the mesoporous silica and active alumina are ball-milled at a speed of 250 rpm for 3 h. After drying in an oven at a temperature of 135℃, the mixture is placed in a calcination furnace and calcined at a temperature of 375℃ for 4 h. After cooling to room temperature, a pretreated carrier is obtained;

[0093] (6) The graphene modified carbon nanotubes are added to the N-methyl pyrrolidone and ultrasonic dispersion is performed at a power of 400 W for 45 min. Then the pretreated carrier is added and mixed. Stirring and mixing are performed at a temperature of 90℃ and a speed of 500 rpm for 15 h. After distillation under reduced pressure, a carbon material composite carrier is obtained;

[0094] (7) The ferric chloride, titanium tetrachloride, copper chloride, and phosphotungstic acid are added to the remaining 1 / 2 of the anhydrous ethanol, and ultrasonic dispersion is performed at a power of 500 W for 30 min to obtain an impregnation solution;

[0095] (8) The carbon material composite carrier is immersed in the impregnation solution three times, and after each immersion, it is dried at a certain temperature. The first time, it is immersed at a temperature of 70℃ for 3 h. After drying, the second time, it is immersed at a temperature of 80℃ for 3 h. After drying, the third time, it is immersed at a temperature of 90℃ for 1.5 h and dried. A catalyst precursor is obtained;

[0096] (9) 3A type molecular sieve is calcined in a calcining furnace at 375°C for 4 hours, and then cooled to room temperature. The cooled molecular sieve is mixed with anhydrous calcium sulfate, magnesium oxide, calcium oxide and bentonite, and then placed in a kneader. Polyvinyl alcohol, ammonium bicarbonate and carbon material composite carrier are added into the kneader in sequence, and then kneaded at room temperature for 45 minutes. The mixture is extruded to form particles with a diameter of 4 mm and a length of 7 mm;

[0097] (10) The particles are placed in a fluidized bed reactor, and nitrogen is introduced into the reactor. The temperature is raised to 225°C at a rate of 2.5°C / min, and then switched to a mixture of hydrogen chloride and chlorine gas with a volume ratio of 1:2. The temperature is raised to 275°C and activated for 9 hours. Nitrogen is introduced into the reactor again, and the temperature is lowered to 165°C. The temperature is kept for 3 hours, and then cooled to room temperature to obtain a self-dehydrated solid acid catalyst;

[0098] (11) The self-dehydrated solid acid catalyst is added to the first chlorination tower, the second chlorination tower and the third chlorination tower. The loading amount of the catalyst is 40% of the volume of the chlorination tower;

[0099] (12) The p-chloronitrobenzene raw material is fed from the top of the first chlorination tower to the tower and flows to the bottom of the tower. Chlorine gas is introduced into the tower from the bottom of the first chlorination tower at a flow rate of 0.45 t / h and flows to the top of the tower. The temperature of the first chlorination tower is controlled at 70°C, and the pressure is -3 Kpa. Chlorination reaction is carried out, and the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0100] (13) The chlorination liquid overflowed from the first chlorination tower enters the top of the second chlorination tower and flows to the bottom of the tower. Chlorine gas is introduced into the tower from the bottom of the second chlorination tower at a flow rate of 0.3 t / h and flows to the top of the tower. The temperature of the second chlorination tower is controlled at 80°C, and the pressure is -3 Kpa. Chlorination reaction is carried out, and the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0101] (14) The chlorination liquid overflowed from the second chlorination tower enters the top of the third chlorination tower and flows to the bottom of the tower. Chlorine gas is introduced into the tower from the bottom of the third chlorination tower at a flow rate of 0.15 t / h and flows to the top of the tower. The temperature of the third chlorination tower is controlled at 90°C, and the pressure is -3 Kpa. Chlorination reaction is carried out, and the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline. The chlorination liquid overflows from the third tower to the buffer tank;

[0102] (15) The hydrogen chloride gas and unreacted chlorine gas in the tail gas main pipeline first remove organic matter through a trap, and then are cooled to 30 DEG C through a cooler to condense and recover p-nitrochlorobenzene and 3,4-dichloronitrobenzene. The condensed gas enters a filter to remove solid particles, and the purified gas enters a three-stage falling film absorber to generate 31% industrial hydrochloric acid by absorption with desalted water. The remaining gas enters a two-stage alkali absorption tower to generate 9% sodium hypochlorite solution by absorption with 7% NaOH solution, and is finally discharged after being adsorbed by activated carbon;

[0103] (16) The chlorination liquid in the buffer tank is transported to a first deacidification kettle at a flow rate of 3 t / h, and compressed air is introduced to bubble to remove hydrogen chloride at a temperature of 95 DEG C. The chlorination liquid in the first deacidification kettle overflows into a second deacidification kettle, and compressed air is further introduced to remove hydrogen chloride at a temperature of 105 DEG C. The deacidified chlorination liquid enters a crude product tank;

[0104] (17) The chlorination liquid in the crude product tank is transported to a light component removal tower at a flow rate of 3.5 t / h, the kettle temperature of the light component removal tower is controlled at 175 DEG C, the overhead temperature is controlled at 165 DEG C, p-chloronitrobenzene is evaporated from the top of the tower to be recycled, and the kettle material enters a heavy component removal tower at a flow rate of 2.25 t / h, the kettle temperature of the heavy component removal tower is controlled at 190 DEG C, the overhead temperature is controlled at 180 DEG C, and tar is collected from the kettle, and the overhead material is crystallized and purified to obtain 3,4-dichloronitrobenzene.

[0105] The 3,4-dichloronitrobenzene prepared in Example 2 is detected by a liquid chromatograph, and the specific results are shown in Table 1. Figure 3

[0106] Example 3

[0107] The process method for producing 3,4-dichloronitrobenzene without waste water in this example comprises the following steps:

[0108] (1) 120 parts of graphene oxide dispersion liquid with a concentration of 5 mg / mL, 30 parts of hydroxylated multi-walled carbon nanotubes, and 15 parts of hydrazine hydrate are weighed according to weight parts;

[0109] (2) The hydroxylated multi-walled carbon nanotubes are added to the graphene oxide dispersion liquid, and ultrasonic dispersion is performed at a power of 600 W for 60 min to obtain a mixed suspension;

[0110] (3) The mixed suspension is placed in a reaction kettle, and hydrothermal reaction is performed at a temperature of 180 DEG C for 18 h. After cooling to 80 DEG C, hydrazine hydrate is added, and the reduction reaction is continued for 6 h. After freeze-drying, graphene modified carbon nanotubes are obtained.

[0111] ​(4) Weigh out the following components by weight: 120 parts of mesoporous silica, 30 parts of activated alumina, 15 parts of graphene-modified carbon nanotubes, 8 parts of vinyltris(β-methoxyethoxy)silane, 25 parts of ferric chloride, 20 parts of titanium tetrachloride, 10 parts of copper chloride, 16 parts of phosphotungstic acid, 50 parts of type 3A molecular sieve, 20 parts of anhydrous calcium sulfate, 5 parts of magnesium oxide, 5 parts of calcium oxide, 12 parts of bentonite, 8 parts of polyvinyl alcohol, 5 parts of ammonium bicarbonate, 500 parts of anhydrous ethanol, 60 parts of N-methylpyrrolidone, and 30 parts of deionized water.

[0112] (5) Add vinyltris(β-methoxyethoxy)silane to 1 / 2 anhydrous ethanol, stir evenly, then add mesoporous silica and activated alumina, ball mill and mix at 300 rpm for 4 hours, place in an oven and dry at 150°C, then place in a calcining furnace and calcinate at 400°C for 5 hours, cool at room temperature to obtain the pretreated carrier.

[0113] (6) Graphene-modified carbon nanotubes were added to N-methylpyrrolidone and ultrasonically dispersed at 500W for 60min. Then, pretreated carrier was added and mixed. The mixture was stirred at 600rpm for 20h at 100℃ and then distilled under reduced pressure to obtain carbon material composite carrier.

[0114] (7) Add ferric chloride, titanium tetrachloride, copper chloride and phosphotungstic acid to the remaining 1 / 2 of anhydrous ethanol and ultrasonically disperse at 600W for 40min to obtain impregnation solution.

[0115] (8) The carbon material composite support was immersed in the impregnation liquid three times, and dried in stages after each immersion. The first immersion was carried out at 80°C for 4 hours, the second immersion was carried out at 90°C for 4 hours, and the third immersion was carried out at 100°C for 2 hours to obtain the catalyst precursor.

[0116] (9) The 3A molecular sieve was placed in a calcining furnace and calcined at 400°C for 5 hours. After cooling at room temperature, it was mixed evenly with anhydrous calcium sulfate, magnesium oxide, calcium oxide and bentonite. The mixture was placed in a kneader and then polyvinyl alcohol, ammonium bicarbonate, carbon material composite carrier and deionized water were added in sequence. The mixture was kneaded at room temperature for 60 minutes and then extruded to obtain particles with a diameter of 5 mm and a length of 10 mm.

[0117] (10) The particles were placed in a fluidized bed reactor and nitrogen gas was introduced for protection. The temperature was increased to 250°C at a rate of 3°C / min. The mixture of hydrogen chloride and chlorine was switched to a mixture of hydrogen chloride and chlorine with a volume ratio of 1:3. The temperature was increased to 300°C for 12 hours. Nitrogen gas was introduced and the temperature was lowered to 180°C. The temperature was maintained for 4 hours and then cooled to room temperature to obtain a dehydrated solid acid catalyst.

[0118] (11) adding self-dehydrated solid acid catalyst into the first, second and third chlorination towers, and the loading amount of the catalyst is 50% of the volume of the chlorination tower;

[0119] (12) feeding p-chloronitrobenzene raw material into the first chlorination tower from the top and flowing to the bottom, feeding chlorine gas into the first chlorination tower from the bottom at a flow rate of 0.6 t / h and flowing to the top, controlling the temperature of the first chlorination tower at 80°C and the pressure at -5 Kpa to perform chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top enter the tail gas main pipeline;

[0120] (13) overflowing the chlorination liquid of the first chlorination tower into the top of the second chlorination tower and flowing to the bottom, feeding chlorine gas into the second chlorination tower from the bottom at a flow rate of 0.4 t / h and flowing to the top, controlling the temperature of the second chlorination tower at 90°C and the pressure at -5 Kpa to perform chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top enter the tail gas main pipeline;

[0121] (14) overflowing the chlorination liquid of the second chlorination tower into the top of the third chlorination tower and flowing to the bottom, feeding chlorine gas into the third chlorination tower from the bottom at a flow rate of 0.2 t / h and flowing to the top, controlling the temperature of the third chlorination tower at 100°C and the pressure at -5 Kpa to perform chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top enter the tail gas main pipeline, and the chlorination liquid overflows from the third tower to the buffer tank;

[0122] (15) the hydrogen chloride gas and unreacted chlorine gas in the tail gas main pipeline first pass through a trap to remove organic matter, then pass through a cooler to be cooled to 40°C, condense to recover p-nitrochlorobenzene and 3,4-dichloronitrobenzene, the condensed gas enters a filter to remove solid particles, and the purified gas enters a three-stage falling film absorber to generate industrial hydrochloric acid with a mass fraction of 32% by absorbing with desalted water, the remaining gas enters a two-stage alkali absorption tower to generate sodium hypochlorite solution with a mass fraction of 10% by absorbing with NaOH solution with a mass fraction of 10%, and finally is discharged after being adsorbed by activated carbon;

[0123] (16) feeding the chlorination liquid in the buffer tank into the first deacidification kettle at a flow rate of 4 t / h, and bubbling compressed air into the first deacidification kettle at a temperature of 100°C to remove hydrogen chloride, overflowing the chlorination liquid in the first deacidification kettle into the second deacidification kettle, and further bubbling compressed air into the second deacidification kettle at a temperature of 110°C to remove hydrogen chloride, and the deacidified chlorination liquid enters the crude product tank;

[0124] (17) The chlorination liquid in the crude product tank is transported to the light-removing tower at a flow rate of 4.5 t / h, the tower bottom temperature of the light-removing tower is controlled at 80°C, the tower top temperature is controlled at 170°C, p-chloronitrobenzene is evaporated at the tower top and recycled, the tower bottom material enters the heavy-removing tower at a flow rate of 3 t / h, the tower bottom temperature of the heavy-removing tower is controlled at 195°C, the tower top temperature is controlled at 185°C, and the tar is collected at the tower bottom, and the tower top material is crystallized and purified to obtain 3,4-dichloronitrobenzene.

[0125] The 3,4-dichloronitrobenzene prepared in Example 3 is detected by a liquid chromatograph, and the specific results are shown in Table 1. Figure 4

[0126] Experimental Example

[0127] The products of Examples 1-3 are selected as samples, and appearance and component detection are performed, including 3,4-dichloronitrobenzene purity, 2,5-dichloronitrobenzene content, and 2,3-dichloronitrobenzene content, and the specific detection results are shown in Table 1.

[0128] Table 1: Detection results of Examples 1-3

[0129]

[0130] As can be seen from the examples in Table 1, the 3,4-dichloronitrobenzene prepared by the method of Examples 1-3 has a purity of greater than or equal to 99.5%, and it can be seen that the carbon material composite carrier loaded with multiple active sites of metal chlorides is used to prepare a self-dehydration type solid acid catalyst, the catalyst itself has water absorption capacity, the trace amount of water generated in the reaction is immediately captured by the molecular sieve and calcium sulfate, avoiding the participation of water in the side reaction, reducing the loss of hydrogen chloride dissolved, and maintaining a water-free environment in the reaction system. The Lewis acid site (metal chloride) on the catalyst dominates the chlorination reaction, while the Bronsted acid site (phosphotungstic acid) preferentially promotes the generation of 3,4-isomers, and the dual-function synergistically improves the selectivity of 3,4-isomers; and the dehydration component on the catalyst remains stable in a water-containing atmosphere, avoiding the loss of metal chlorides, while the dehydration component can be regenerated in situ at 250-300°C, and the active component metal chlorides can be periodically activated in a chlorine atmosphere, realizing the whole life cycle of the catalyst without wastewater treatment.

[0131] ​The application adds graphene modified carbon nanotubes to make the self-dehydration type solid acid catalyst have a three-dimensional network structure. Graphene has a two-dimensional planar structure, and carbon nanotubes have a one-dimensional linear structure. The two are intertwined to form a stable, porous three-dimensional network skeleton. The skeleton provides a large specific surface area and a firm anchoring point for the subsequent supported metal chloride active center. The strong adsorption effect makes the volatile or soluble metal chloride active component be firmly fixed. Especially in a reaction environment containing chlorine and hydrogen chloride, the catalyst life is greatly extended. At the same time, the three-dimensional network makes the catalyst particles have very high mechanical strength, can withstand the long-term flow scouring of the material in the chlorination tower, reduces the pulverization, and reduces the system pressure drop. Moreover, graphene and carbon nanotubes are thermal conductors. The three-dimensional network formed by them can form a microcirculation heat dissipation system inside the catalyst, thereby eliminating local hot spots. Chlorination reaction is an exothermic reaction. Due to poor thermal conductivity, traditional catalysts are prone to form local high temperature, leading to excessive chlorination, carbon deposition and catalyst sintering inactivation. The graphene-carbon nanotube network can quickly conduct the reaction heat out, so that the catalyst bed temperature is uniformly distributed. The uniform temperature field is conducive to the reaction towards the target product, inhibits the side reaction, thereby effectively improving the selectivity. The three-dimensional network structure also has a hierarchical pore, which provides a high-speed channel for the diffusion of reactants and products, reducing the internal diffusion resistance. The reactants can more quickly contact the internal active sites, and the products can also quickly leave, thereby improving the intrinsic reaction rate and the effective utilization rate of the catalyst. At the same time, the abundant pores also provide sufficient space and contact interface for the dehydration component, facilitating efficient capture of reaction-generated water and strengthening the self-dehydration function. The defects and edge sites of graphene and carbon nanotubes can act as Lewis acid sites, or produce a synergistic effect with the supported phosphotungstic acid (Bronsted acid), to adjust the electronic effect of the catalyst surface and regulate the reaction path from the electronic level, further strengthening the selectivity of the 3,4-position chlorination reaction.

[0132] At the same time, the application adopts multi-stage chlorination tower for grading chloro gas feeding and circulating stirring. The tower has a large height-diameter ratio. Chlorine gas stays in the tower for a long time during the rising process. The chlorination tower is filled with catalyst fillers, which can form more turbulence and effectively improve the gas-liquid contact effect, thereby improving the reaction efficiency, reducing the generation of side reactions, and reducing the consumption of chlorine gas, thereby improving the selectivity, conversion rate, and product quality of the material. At the same time, due to the large height-diameter ratio of the chlorination tower, the mass and heat transfer are good, the temperature can be controlled smoothly, and the chlorination reaction does not need to add a large amount of ferric chloride catalyst to ensure the chlorination efficiency. Instead, a self-dehydration type solid acid catalyst is used. This not only prolongs the life, but also reduces waste generation. The 3,4-dichloronitrobenzene production process provided by the application has easy-to-obtain reaction raw materials, simple operation, and is suitable for continuous industrial production. The product has high purity.

[0133] Therefore, the process for producing 3,4-dichloronitrobenzene without waste water provided by the application has good application effect.

[0134] The above is the ideal embodiment according to the application, and the above description can be changed and modified by the relevant staff without deviating from the technical idea of the application. The technical scope of the application is not limited to the content of the specification, and must be determined according to the scope of claims.

Claims

1. A method for preparing a catalyst for the wastewater-free production of 3,4-dichloronitrobenzene, characterized in that, The raw materials, by weight, include the following components: Mesoporous silica 100-120 parts, activated alumina 20-30 parts, graphene-modified carbon nanotubes 5-15 parts, vinyltris(β-methoxyethoxy)silane 3-8 parts, ferric chloride 15-25 parts, titanium tetrachloride 10-20 parts, copper chloride 6-10 parts, phosphotungstic acid 8-16 parts, type 3A molecular sieve 30-50 parts, anhydrous calcium sulfate 10-20 parts, magnesium oxide 3-5 parts, calcium oxide 3-5 parts, bentonite 10-12 parts, polyvinyl alcohol 4-8 parts, ammonium bicarbonate 3-5 parts, anhydrous ethanol 300-500 parts, N-methylpyrrolidone 40-60 parts, deionized water 20-30 parts; The method for preparing the catalyst includes the following steps: S1. Weigh each raw material component according to the weight percentage; S2. Add vinyltris(β-methoxyethoxy)silane to 1 / 2 anhydrous ethanol, stir evenly, then add mesoporous silica and activated alumina, ball mill and mix at 200~300 rpm for 2~4 hours, place in an oven and dry at 120~150℃, then place in a calcination furnace and calcine at 350~400℃ for 3~5 hours, cool at room temperature to obtain the pretreated carrier; S3. Add graphene-modified carbon nanotubes to N-methylpyrrolidone and ultrasonically disperse them at a power of 300~500W for 30~60min. Then add the pretreated carrier and mix. Stir and mix at a temperature of 80~100℃ and a speed of 400~600rpm for 10~20h. Distill under reduced pressure to obtain carbon material composite carrier. S4. Add ferric chloride, titanium tetrachloride, copper chloride, and phosphotungstic acid to the remaining 1 / 2 of anhydrous ethanol, and ultrasonically disperse at a power of 400~600W for 20~40min to obtain the impregnation solution. S5. The carbon material composite support is immersed in the impregnation solution three times, and dried in stages after each immersion. The first immersion is carried out at a temperature of 60~80℃ for 2~4 hours. After drying, the second immersion is carried out at a temperature of 70~90℃ for 2~4 hours. After drying, the third immersion is carried out at a temperature of 80~100℃ for 1~2 hours and then dried to obtain the catalyst precursor. S6. Place the 3A type molecular sieve in a calcination furnace and calcine and activate it at 350~400℃ for 3~5 hours. After cooling at room temperature, mix it evenly with anhydrous calcium sulfate, magnesium oxide, calcium oxide and bentonite. Place it in a kneader and then add polyvinyl alcohol, ammonium bicarbonate, carbon material composite carrier and deionized water in sequence. Knead at room temperature for 30~60 minutes and extrude to obtain particles with a diameter of 3~5mm and a length of 5~10mm. S7. Place the particles in a fluidized bed reactor, introduce nitrogen for protection, heat to 200-250℃ at a rate of 2-3℃ / min, switch to a hydrogen chloride-chlorine mixture, wherein the volume ratio of hydrogen chloride to chlorine is 1:1-3, heat to 250-300℃ for activation for 6-12 hours, then introduce nitrogen and cool to 150-180℃, hold for 2-4 hours, and cool to room temperature to obtain a dehydrated solid acid catalyst. The preparation method of graphene-modified carbon nanotubes in step S1 includes the following steps: A1. Weigh 100-120 parts of graphene oxide dispersion with a concentration of 1-5 mg / mL, 10-30 parts of hydroxylated multi-walled carbon nanotubes, and 5-15 parts of hydrazine hydrate, respectively, by weight. A2. Add hydroxylated multi-walled carbon nanotubes to the graphene oxide dispersion and ultrasonically disperse at a power of 400~600W for 30~60min to obtain a mixed suspension. A3. Place the mixed suspension in a reaction vessel and perform a hydrothermal reaction at 120~180℃ for 12~18h. Cool the temperature to 60~80℃ and add hydrazine hydrate. Continue the reduction reaction for 4~6h and freeze-dry to obtain graphene-modified carbon nanotubes.

2. A process for producing 3,4-dichloronitrobenzene without wastewater, characterized in that, Includes the following steps: (1) Add catalyst to the primary chlorination tower, secondary chlorination tower and tertiary chlorination tower; (2) The p-chloronitrobenzene raw material is transported from the top of the primary chlorination tower to the tower and flows to the bottom of the tower. Chlorine gas is bubbled from the bottom of the primary chlorination tower to the tower and flows towards the top of the tower for chlorination reaction. The generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline. (3) The chlorinated liquid overflows from the primary chlorination tower into the top of the secondary chlorination tower and flows to the bottom of the tower. Chlorine gas is bubbled from the bottom of the secondary chlorination tower into the tower and flows towards the top of the tower to carry out the chlorination reaction. The generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline. (4) The chlorinated liquid overflows from the secondary chlorination tower into the top of the tertiary chlorination tower and flows to the bottom of the tower. The chlorine gas is bubbled from the bottom of the tertiary chlorination tower into the tower and flows towards the top of the tower to carry out the chlorination reaction. The generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline. The chlorinated liquid overflows from the tertiary tower to the buffer tank. (5) Hydrogen chloride gas and unreacted chlorine gas in the tail gas main pipeline are first removed by a collector to remove organic matter, and then cooled to 20~40℃ by a cooler. The gas is condensed and recovered from p-nitrochlorobenzene and 3,4-dichloronitrobenzene. The condensed gas enters a filter to remove solid particles. The purified gas enters a three-stage falling film absorber and is absorbed by demineralized water to generate industrial hydrochloric acid with a mass fraction of 30%~32%. The remaining gas after demineralized water absorption treatment enters a two-stage alkali absorption tower and is absorbed and reacted by a NaOH solution with a mass fraction of 5%~10%. The reaction generates sodium hypochlorite solution with a mass fraction of 8%~10%. Finally, the gas is adsorbed by activated carbon to meet emission standards. (6) The chlorinated liquid in the buffer tank is transported to the first-stage deacidification vessel. Compressed air is introduced at a temperature of 90~100℃ to remove hydrogen chloride by bubbling. The chlorinated liquid in the first-stage deacidification vessel overflows into the second-stage deacidification vessel. Compressed air is introduced at a temperature of 100~110℃ to further remove hydrogen chloride. The deacidified chlorinated liquid enters the crude product tank. (7) The chlorination liquid in the crude product tank is transported to the light product removal tower. The temperature of the bottom of the light product removal tower is controlled at 170~180℃ and the temperature of the top of the tower is controlled at 160~170℃. The p-chloronitrobenzene is distilled off from the top of the tower for recycling. The bottom material enters the heavy product removal tower. The temperature of the bottom of the heavy product removal tower is controlled at 185~195℃ and the temperature of the top of the tower is controlled at 175~185℃. Tar is collected from the bottom of the tower. The top material is crystallized and purified to obtain 3,4-dichloronitrobenzene. The catalyst is a self-dehydrating solid acid catalyst prepared by the preparation method described in claim 1.

3. The process for producing 3,4-dichloronitrobenzene without wastewater according to claim 2, characterized in that, In step (1), the loading amount of the self-dehydrating solid acid catalyst in the primary chlorination tower, secondary chlorination tower, and tertiary chlorination tower is 30% to 50% of the volume of each chlorination tower.

4. The process for producing 3,4-dichloronitrobenzene without wastewater according to claim 2, characterized in that, In step (2), the temperature of the primary chlorination tower is 60~80℃, the pressure is -5~-1Kpa, and the flow rate of chlorine gas in the primary chlorination tower is 0.3~0.6t / h.

5. The process for producing 3,4-dichloronitrobenzene without wastewater according to claim 2, characterized in that, In step (3), the temperature of the secondary chlorination tower is 70~90℃, the pressure is -5~-1Kpa, and the flow rate of chlorine gas in the secondary chlorination tower is 0.2~0.4t / h.

6. The process for producing 3,4-dichloronitrobenzene without wastewater according to claim 2, characterized in that, In step (4), the temperature of the three-stage chlorination tower is 80~100℃, the pressure is -5~-1Kpa, and the flow rate of chlorine gas in the three-stage chlorination tower is 0.1~0.2t / h.

7. The process for producing 3,4-dichloronitrobenzene without wastewater according to claim 2, characterized in that, In step (5), the mass fraction of industrial hydrochloric acid is 30%~32%, the mass fraction of NaOH solution is 5%~10%, and the mass fraction of sodium hypochlorite solution is 8%~10%.

8. The process for producing 3,4-dichloronitrobenzene without wastewater according to claim 2, characterized in that, In step (6), the flow rate of the chlorinated liquid in the buffer tank to the primary deacidification reactor is 2~4 t / h.

9. The process for producing 3,4-dichloronitrobenzene without wastewater according to claim 2, characterized in that, In step (7), the flow rate of the chlorinated liquid in the crude product tank to the light product removal tower is 2.5~4.5t / h, and the flow rate of the bottom material entering the heavy product removal tower is 1.5~3t / h.

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