A catalyst, a preparation method thereof and a continuous chlorination production process of 3,4-dichloronitrobenzene

Abstract

The present application relates to the technical fields of chemical synthesis, and discloses a kind of catalyst and preparation method and the continuous chlorination production process of 3,4-dichloronitrobenzene, wherein the continuous chlorination production process of 3,4-dichloronitrobenzene includes the following steps: (1) adding multi-stage channel supported metal chloride catalyst into primary chlorination tower, secondary chlorination tower and tertiary chlorination tower; (2) feeding p-chloronitrobenzene raw material into primary chlorination tower, secondary chlorination tower and tertiary chlorination tower in sequence and introducing chlorine gas for chlorination reaction, the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower, enter the tail gas main pipeline, and the reacted chlorination liquid is fed into primary deacidification kettle and secondary deacidification kettle in sequence for deacidification treatment; (3) the deacidified chlorination liquid is fed into light-removing tower to distill p-chloronitrobenzene for recycling, the tower kettle material is fed into heavy-removing tower for treatment, tar is recovered from the tower kettle, and 3,4-dichloronitrobenzene is obtained by crystallization and purification of the tower top material.

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 continuous chlorination production process of 3,4-dichloronitrobenzene. 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 uses batch kettle chlorination. Under the action of anhydrous ferric chloride catalyst, melt state p-chloronitrobenzene is added into a porcelain-lined 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 purification by post-treatment 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 for nitration reaction to generate about 90% of 3,4-dichloronitrobenzene and about 10% of 2,3-dichloronitrobenzene. The 3,4-dichloronitrobenzene is purified 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 uses a bubbling method. 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. This results in high raw material consumption and poor product quality. 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, which leads to low production capacity and equipment efficiency. In addition, due to the extremely short residence time of chlorine gas in the kettle, a large amount of anhydrous ferric chloride must be added as a catalyst to ensure the normal progress of chlorination. The compounds generated by the side reaction adhere to the surface of the catalyst, which seriously affects the activity and service life of the catalyst. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a kind of catalyst and its preparation method and the continuous chlorination production process of 3,4-dichloronitrobenzene.

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

[0006] A kind of catalyst for continuous chlorination production of 3,4-dichloronitrobenzene, the raw materials include the following components by weight fraction:

[0007] 100~120 parts of tetraethyl orthosilicate, 10~20 parts of block copolymer F127, 5~15 parts of polyurethane foam, 2~4 parts of (3-aminopropyl)triethoxysilane, 300~600 parts of anhydrous ethanol, 50~100 parts of deionized water, 15~25 parts of ferric chloride, 10~20 parts of zinc chloride, 2~5 parts of lanthanum chloride, 1~3 parts of cerium chloride, and 3~8 parts of acetylacetone.

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

[0009] S1, each raw material component is weighed by weight fraction;

[0010] S2, (3-aminopropyl)triethoxysilane is added to 1 / 3 of anhydrous ethanol and stirred uniformly to obtain a treatment liquid;

[0011] S3, the polyurethane foam is cut into small pieces of 5×5×5mm, calcined at 300~400℃ under nitrogen protection for 2~3h, and then placed in the treatment liquid after cooling, soaked in a water bath at 30~40℃ for 12~24h, and then taken out and dried to obtain a macroporous template;

[0012] S4, tetraethyl orthosilicate is added to 1 / 3 of anhydrous ethanol and mixed uniformly, hydrochloric acid with a mass fraction of 5%~10% is added to adjust the pH to 2~3, block copolymer F127 and the macroporous template are added, and stirring is carried out at a speed of 300~500rpm under the condition of a water bath at 40~60℃ for 1~2h, deionized water is slowly added dropwise, and the mixture is aged for 12~24h and then placed in a high-pressure reaction kettle and reacted at a temperature of 100~120℃ for 24~48h, the reaction product is placed in a calcination furnace and heated to 350~450℃ at a rate of 1~2℃ / min, and then kept at the temperature for 4~6h and cooled at room temperature to obtain a hierarchical pore silica carrier;

[0013] S5, ferric chloride, zinc chloride, lanthanum chloride, cerium chloride, and acetylacetone are sequentially added to the remaining 1 / 3 of anhydrous ethanol, and ultrasonic treatment is carried out at a power of 200~400W for 20~40min to obtain an impregnation liquid;

[0014] S6, the hierarchical pore silica carrier is preheated to 80~100℃ and vacuum dehydrated for 1~2h, then immersed in the impregnation liquid at a temperature of 30~50℃ for 4~8h, sealed and aged at a temperature of 25~35℃ for 12~24h, and then placed in an oven at 80~120℃ and dried for 2~4h to obtain a catalyst precursor;

[0015] S7, the catalyst precursor is placed in a tube furnace, nitrogen is introduced for protection, the temperature is raised to 200-250℃ at a rate of 2-3℃ / min, then a mixture of chlorine and nitrogen with a chlorine volume fraction of 5%-15% is introduced, and activated for 4-8h, then switch to dry nitrogen, the temperature is lowered to 150-180℃, and a hydrogen chloride gas with a volume fraction of 0.1%-0.5% is introduced for treatment for 2-4h, and then cooled at room temperature to obtain a multi-stage pore loaded metal chloride catalyst.

[0016] Further, a continuous chlorination production process of 3,4-dichloronitrobenzene includes the following steps:

[0017] (1) adding a multi-stage pore loaded metal chloride catalyst into a first chlorination tower, a second chlorination tower and a third chlorination tower;

[0018] (2) feeding p-chloronitrobenzene raw material from the top of the first chlorination tower into the tower and flowing to the bottom of the tower, and bubbling chlorine gas from the bottom of the first chlorination tower into the tower and flowing to the top of the tower for chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top of the tower into a tail gas main pipeline;

[0019] (3) the chlorination liquid of the first chlorination tower overflowing into the top of the second chlorination tower and flowing to the bottom of the tower, and bubbling chlorine gas from the bottom of the second chlorination tower into the tower and flowing to the top of the tower for chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top of the tower into the tail gas main pipeline;

[0020] (4) the chlorination liquid of the second chlorination tower overflowing into the top of the third chlorination tower and flowing to the bottom of the tower, and bubbling chlorine gas from the bottom of the third chlorination tower into the tower and flowing to the top of the tower for chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top of the tower into the tail gas main pipeline, and the chlorination liquid overflowing from the third tower into a buffer tank;

[0021] (5) feeding the chlorination liquid in the buffer tank into a first deacidification kettle, bubbling compressed air into the first deacidification kettle at a temperature of 90-100℃ to remove hydrogen chloride, and the chlorination liquid in the first deacidification kettle overflowing into a second deacidification kettle, and further bubbling compressed air into the second deacidification kettle at a temperature of 100-110℃ to remove hydrogen chloride, and the deacidified chlorination liquid entering a crude product tank;

[0022] (6) feeding the chlorination liquid in the crude product tank into a light component removal tower, controlling the temperature of the tower kettle of the light component removal tower to be 170-180℃, and the temperature of the tower top to be 160-170℃, and evaporating p-chloronitrobenzene from the tower top to be recycled, and the tower kettle material entering a heavy component removal tower, controlling the temperature of the tower kettle of the heavy component removal tower to be 185-195℃, and the temperature of the tower top to be 175-185℃, and collecting tar from the tower kettle, and crystallizing and purifying the tower top material to obtain 3,4-dichloronitrobenzene;

[0023] The multi-stage channel supported metal chloride catalyst is the catalyst prepared by the preparation method.

[0024] Further, the loading amount of the multi-stage channel supported metal chloride catalyst in the primary chlorination tower, the secondary chlorination tower and the tertiary chlorination tower in step (1) is 30% to 50% of the volume of the chlorination tower, and the service life of the supported metal chloride catalyst is 4 to 8 months.

[0025] Further, the temperature of the primary chlorination tower in step (2) is 60 to 80 DEG C, the pressure is -5 to -1 Kpa, and the flow rate of the chlorine gas in the primary chlorination tower is 0.3 to 0.6 t / h.

[0026] Further, the temperature of the secondary chlorination tower in step (3) is 70 to 90 DEG C, the pressure is -5 to -1 Kpa, and the flow rate of the chlorine gas in the secondary chlorination tower is 0.2 to 0.4 t / h.

[0027] Further, the temperature of the tertiary chlorination tower in step (4) is 80 to 100 DEG C, the pressure is -5 to -1 Kpa, and the flow rate of the chlorine gas in the tertiary chlorination tower is 0.1 to 0.2 t / h.

[0028] Further, the flow rate of the chlorination liquid in the buffer tank in step (5) transported to the primary deacidification kettle is 2 to 4 t / h.

[0029] Further, the flow rate of the chlorination liquid in the crude product tank in step (6) transported to the light component removal tower is 2.5 to 4.5 t / h, and the flow rate of the kettle material in the heavy component removal tower is 1.5 to 3 t / h.

[0030] In summary, the present application at least includes the following beneficial effects:

[0031] (1) The present application uses multi-stage channel silica as a carrier to support metal chloride to prepare a chlorination catalyst, the macropore of the carrier provides a mass transfer channel, the mesopore provides a reaction site, and the micropore provides an acid site, the synergistic effect of iron, zinc and rare earth in the composite active component can effectively improve the selectivity and carbon deposition resistance of the catalyst, prolong the service life of the catalyst while improving the catalytic performance, meanwhile, the preparation of the catalyst adopts a template method combined with a sol-gel method, can effectively realize the uniform distribution of the active component after impregnation, and finally adopts a special activation process to form active chlorine species by chlorine activation, thereby improving the initial activity of the catalyst and effectively improving the yield of the reaction product.

[0032] (2) The present application adopts multi-stage chlorination tower to divide the feeding and circulating stirring of chlorine, the tower has a large height-diameter ratio, the chlorine stays in the tower for a long time during the rising process, the chlorination tower is filled with catalyst packing, which can form more turbulence and effectively improve the gas-liquid contact effect, thereby improving the reaction efficiency, reducing the generation of side reactions, reducing the consumption of chlorine, and improving the selectivity, conversion rate of the material, and product quality. 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 stably, and a large amount of ferric chloride catalyst does not need to be added to ensure the chlorination efficiency, but a multi-stage pore loaded metal chloride catalyst is used. This not only prolongs the service life, but also reduces waste generation. The 3,4-dichloronitrobenzene production process provided by the present application has easy-to-obtain reaction raw materials, simple operation, is suitable for continuous industrial production, has high product purity, meets the needs of various markets, utilizes by-products, and has significant economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Liquid chromatogram of 3,4-dichloronitrobenzene prepared for Example 1 of the present application;

[0034] Figure 2 Liquid chromatogram of 3,4-dichloronitrobenzene prepared for Example 2 of the present application;

[0035] Figure 3 Liquid chromatogram of 3,4-dichloronitrobenzene prepared for Example 3 of the present application. DETAILED DESCRIPTION

[0036] 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 embodiments.

[0037] It should be noted that, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0038] The present application provides a catalyst, a preparation method thereof, and a continuous chlorination production process of 3,4-dichloronitrobenzene, wherein:

[0039] A continuous chlorination production process of 3,4-dichloronitrobenzene, comprising the following steps:

[0040] (1) 100-120 parts by weight of tetraethyl orthosilicate, 10-20 parts by weight of block copolymer F127, 5-15 parts by weight of polyurethane foam, 2-4 parts by weight of (3-aminopropyl)triethoxysilane, 300-600 parts by weight of anhydrous ethanol, 50-100 parts by weight of deionized water, 15-25 parts by weight of ferric chloride, 10-20 parts by weight of zinc chloride, 2-5 parts by weight of lanthanum chloride, 1-3 parts by weight of cerium chloride, and 3-8 parts by weight of acetylacetone are weighed respectively;

[0041] (2) The (3-aminopropyl)triethoxysilane is added to 1 / 3 of the anhydrous ethanol and stirred uniformly to obtain a treatment solution;

[0042] (3) The polyurethane foam is cut into small pieces of 5*5*5 mm, calcined at 300-400 ℃ for 2-3 h under nitrogen protection, and then placed in the treatment solution and soaked in a water bath at 30-40 ℃ for 12-24 h. After being taken out and dried, a macroporous template is obtained;

[0043] (4) The tetraethyl orthosilicate is added to 1 / 3 of the anhydrous ethanol and mixed uniformly. A 5%-10% hydrochloric acid solution is added dropwise to adjust the pH to 2-3. The block copolymer F127 and the macroporous template are added, and the mixture is stirred at 300-500 rpm for 1-2 h under the condition of a water bath at 40-60 ℃. Deionized water is added dropwise slowly. After being aged for 12-24 h, the mixture is placed in a high-pressure reaction kettle and reacted at 100-120 ℃ for 24-48 h. The reaction product is placed in a calcination furnace and heated to 350-450 ℃ at a rate of 1-2 ℃ / min. After being kept at this temperature for 4-6 h, the product is cooled to room temperature to obtain a hierarchical pore silica carrier;

[0044] (5) The ferric chloride, zinc chloride, lanthanum chloride, cerium chloride, and acetylacetone are sequentially added to the remaining 1 / 3 of the anhydrous ethanol, and ultrasonic treatment is performed at a power of 200-400 W for 20-40 min to obtain an impregnation solution;

[0045] (6) The hierarchical pore silica carrier is preheated to 80-100 ℃ and vacuum dehydrated for 1-2 h. It is then immersed in the impregnation solution at a temperature of 30-50 ℃ for 4-8 h, and sealed and aged at a temperature of 25-35 ℃ for 12-24 h. The carrier is dried in an oven at 80-120 ℃ for 2-4 h to obtain a catalyst precursor;

[0046] (7) The catalyst precursor is placed in a tube furnace, nitrogen protection is performed, and the temperature is raised to 200-250 ℃ at a rate of 2-3 ℃ / min. Then, a 5%-15% chlorine-nitrogen mixed gas is introduced, and the temperature is kept constant for 4-8 h. After that, dry nitrogen is switched in, the temperature is lowered to 150-180 ℃, and a 0.1%-0.5% hydrogen chloride gas is introduced for 2-4 h. After being cooled to room temperature, a hierarchical pore supported metal chloride catalyst is obtained;

[0047] (8) adding multi-stage channel supported metal chloride catalyst into the first, second and third chlorination towers, the loading amount of the catalyst is 30%~50% of the volume of the chlorination tower, and the service life of the catalyst is 4~8 months;

[0048] (9) feeding the p-chloronitrobenzene raw material into the first chlorination tower from the top and flowing to the bottom, feeding the chlorine gas into the first chlorination tower from the bottom at a flow rate of 0.3~0.6t / h and flowing to the top, controlling the temperature of the first chlorination tower to be 60~80℃, and controlling the pressure to be -5~-1Kpa to perform the chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top enter the tail gas main pipeline;

[0049] (10) overflowing the chlorination liquid of the first chlorination tower into the top of the second chlorination tower and flowing to the bottom, feeding the chlorine gas into the second chlorination tower from the bottom at a flow rate of 0.2~0.4t / h and flowing to the top, controlling the temperature of the second chlorination tower to be 70~90℃, and controlling the pressure to be -5~-1Kpa to perform the chlorination reaction, and the generated hydrogen chloride gas and unreacted chlorine gas escaping from the top enter the tail gas main pipeline;

[0050] (11) overflowing the chlorination liquid of the second chlorination tower into the top of the third chlorination tower and flowing to the bottom, feeding the chlorine gas into the third chlorination tower from the bottom at a flow rate of 0.1~0.2t / h and flowing to the top, controlling the temperature of the third chlorination tower to be 80~100℃, and controlling the pressure to be -5~-1Kpa to perform the 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;

[0051] (12) feeding the chlorination liquid in the buffer tank into the first deacidification kettle at a flow rate of 2~4t / h, bubbling the compressed air into the first deacidification kettle at a temperature of 90~100℃ to remove the hydrogen chloride, overflowing the chlorination liquid in the first deacidification kettle into the second deacidification kettle, further bubbling the compressed air into the second deacidification kettle at a temperature of 100~110℃ to remove the hydrogen chloride, and the deacidified chlorination liquid enters the crude product tank;

[0052] (13) feeding the chlorination liquid in the crude product tank into the light component removal tower at a flow rate of 2.5~4.5t / h, controlling the kettle temperature of the light component removal tower to be 170~180℃, controlling the top temperature to be 160~170℃, evaporating the p-chloronitrobenzene from the top to be recycled, feeding the kettle material of the light component removal tower into the heavy component removal tower at a flow rate of 1.5~3t / h, controlling the kettle temperature of the heavy component removal tower to be 185~195℃, controlling the top temperature to be 175~185℃, collecting the tar from the kettle, and crystallizing and purifying the top material to obtain 3,4-dichloronitrobenzene.

[0053] The technical solutions provided by the present application will be described in detail below in combination with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0054] Example 1

[0055] The continuous chlorination production process of 3,4-dichloronitrobenzene in this embodiment includes the following steps:

[0056] (1) 100 parts of tetraethyl orthosilicate, 10 parts of block copolymer F127, 5 parts of polyurethane foam, 2 parts of (3-aminopropyl) triethoxysilane, 300 parts of absolute ethanol, 50 parts of deionized water, 15 parts of ferric chloride, 10 parts of zinc chloride, 2 parts of lanthanum chloride, 1 part of cerium chloride, and 3 parts of acetylacetone are weighed according to the weight fraction;

[0057] (2) The (3-aminopropyl) triethoxysilane is added to 1 / 3 of the absolute ethanol and stirred uniformly to obtain a treatment solution;

[0058] (3) The polyurethane foam is cut into small pieces of 5x5x5mm, calcined at 300℃ for 2h under nitrogen protection, and then placed in the treatment solution and soaked in a water bath at 30℃ for 12h. After being taken out and dried, a macroporous template is obtained;

[0059] (4) The tetraethyl orthosilicate is added to 1 / 3 of the absolute ethanol and mixed uniformly, and the pH is adjusted to 2 by adding 5% hydrochloric acid. The block copolymer F127 and the macroporous template are added, and the mixture is stirred at 300rpm for 1h under the condition of a water bath at 40℃. Deionized water is slowly added dropwise, and the mixture is aged for 12h before being placed in a high-pressure reaction kettle and reacted at 100℃ for 24h. The reaction product is placed in a calcination furnace and heated to 350℃ at a rate of 1℃ / min, and then kept at this temperature for 4h. After cooling to room temperature, a hierarchical pore silica carrier is obtained;

[0060] (5) The ferric chloride, zinc chloride, lanthanum chloride, cerium chloride, and acetylacetone are sequentially added to the remaining 1 / 3 of the absolute ethanol, and ultrasonic treatment is performed at a power of 200W for 20min to obtain an impregnation solution;

[0061] (6) The hierarchical pore silica carrier is preheated to 80℃ and vacuum dehydrated for 1h. It is then immersed in the impregnation solution at a temperature of 30℃ for 4h, sealed and aged at a temperature of 25℃ for 12h, and dried in an oven at 80℃ for 2h to obtain a catalyst precursor;

[0062] (7) The catalyst precursor is placed in a tube furnace, and nitrogen protection is performed. The temperature is increased to 200℃ at a rate of 2℃ / min, and then a mixture of chlorine gas with a volume fraction of 5% chlorine-nitrogen is introduced. After being kept at this temperature for 4h, dry nitrogen is switched in, and the temperature is reduced to 150℃. A hydrogen chloride gas with a volume fraction of 0.1% is introduced for 2h, and then the temperature is cooled to room temperature to obtain a hierarchical pore supported metal chloride catalyst;

[0063] (8) adding multi-stage channel supported metal chloride catalyst into the first, second and third chlorination towers, the loading amount of the catalyst is 30% of the volume of the chlorination tower, and the service life of the catalyst is 4 months;

[0064] (9) feeding the p-chloronitrobenzene raw material into the first chlorination tower from the top of the tower and flowing to the bottom of the tower, feeding the chlorine gas into the first chlorination tower from the bottom of the tower at a flow rate of 0.3 t / h and flowing to the top of the tower, controlling the temperature of the first chlorination tower to be 60°C and the pressure to be -1 Kpa to perform the chlorination reaction, and letting the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0065] (10) letting the chlorination liquid of the first chlorination tower overflow into the top of the second chlorination tower and flow to the bottom of the tower, feeding the chlorine gas into the second chlorination tower from the bottom of the tower at a flow rate of 0.2 t / h and flowing to the top of the tower, controlling the temperature of the second chlorination tower to be 70°C and the pressure to be -1 Kpa to perform the chlorination reaction, and letting the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline;

[0066] (11) letting the chlorination liquid of the second chlorination tower overflow into the top of the third chlorination tower and flow to the bottom of the tower, feeding the chlorine gas into the third chlorination tower from the bottom of the tower at a flow rate of 0.1 t / h and flowing to the top of the tower, controlling the temperature of the third chlorination tower to be 80°C and the pressure to be -1 Kpa to perform the chlorination reaction, letting the generated hydrogen chloride gas and unreacted chlorine gas escape from the top of the tower and enter the tail gas main pipeline, and letting the chlorination liquid overflow from the third tower to the buffer tank;

[0067] (12) feeding the chlorination liquid in the buffer tank into the first deacidification kettle at a flow rate of 2 t / h, bubbling the compressed air into the first deacidification kettle at a temperature of 90°C to remove the hydrogen chloride, letting the chlorination liquid in the first deacidification kettle overflow into the second deacidification kettle, further bubbling the compressed air into the second deacidification kettle at a temperature of 100°C to remove the hydrogen chloride, and letting the deacidified chlorination liquid enter the crude product tank;

[0068] (13) feeding the chlorination liquid in the crude product tank into the light component removal tower at a flow rate of 2.5 t / h, controlling the kettle temperature of the light component removal tower to be 170°C and the top temperature to be 160°C, evaporating the p-chloronitrobenzene from the top of the tower to be recycled, letting the kettle material of the light component removal tower enter the heavy component removal tower at a flow rate of 1.5 t / h, controlling the kettle temperature of the heavy component removal tower to be 185°C and the top temperature to be 175°C, collecting the tar from the kettle of the heavy component removal tower, crystallizing and purifying the material from the top of the tower, and obtaining 3,4-dichloronitrobenzene.

[0069] The 3,4-dichloronitrobenzene prepared in Example 1 was detected by using a liquid chromatograph, and the specific results are shown in Table 1. Figure 1

[0070] Example 2

[0071] ​The continuous chlorination production process of 3,4-dichloronitrobenzene in the embodiment comprises the following steps:

[0072] (1) 110 parts of tetraethyl orthosilicate, 15 parts of block copolymer F127, 10 parts of polyurethane foam, 3 parts of (3-aminopropyl) triethoxysilane, 450 parts of anhydrous ethanol, 75 parts of deionized water, 20 parts of ferric chloride, 15 parts of zinc chloride, 3 parts of lanthanum chloride, 2 parts of cerium chloride, and 5 parts of acetylacetone are weighed according to the weight fraction;

[0073] (2) The (3-aminopropyl) triethoxysilane is added to 1 / 3 of the anhydrous ethanol and stirred uniformly to obtain a treatment solution;

[0074] (3) The polyurethane foam is cut into small pieces of 5x5x5mm, calcined at 350℃ for 2.5h under nitrogen protection, and then placed in the treatment solution and soaked in a water bath at 35℃ for 18h. After being taken out and dried, a macroporous template is obtained;

[0075] (4) The tetraethyl orthosilicate is added to 1 / 3 of the anhydrous ethanol and mixed uniformly, and the pH is adjusted to 2.5 by adding 7.5% hydrochloric acid. The block copolymer F127 and the macroporous template are added and stirred at a speed of 450rpm for 1.5h under a water bath at 50℃. Deionized water is slowly added, and the mixture is aged for 18h and then placed in a high-pressure reaction kettle and reacted at a temperature of 110℃ for 36h. The reaction product is placed in a calcination furnace and heated to 400℃ at a rate of 1.5℃ / min, and then kept at this temperature for 5h. After cooling, a hierarchical pore silica carrier is obtained;

[0076] (5) The ferric chloride, zinc chloride, lanthanum chloride, cerium chloride, and acetylacetone are sequentially added to the remaining 1 / 3 of the anhydrous ethanol, and ultrasonic treatment is performed at a power of 300W for 30min to obtain an impregnation solution;

[0077] (6) The hierarchical pore silica carrier is preheated to 90℃ and vacuum dehydrated for 1.5h. It is then placed in the impregnation solution and impregnated at a temperature of 40℃ for 6h. After being sealed and aged at a temperature of 30℃ for 18h, it is dried in an oven at 100℃ for 3h to obtain a catalyst precursor;

[0078] (7) The catalyst precursor is placed in a tube furnace, nitrogen is introduced for protection, and the temperature is raised to 225℃ at a rate of 2.5℃ / min. Then, a mixture of chlorine gas and nitrogen gas with a chlorine gas volume fraction of 10% is introduced, and the temperature is kept constant for 6h. Then, dry nitrogen is switched in, the temperature is lowered to 165℃, and a hydrogen chloride gas with a volume fraction of 0.3% is introduced for treatment for 3h. After cooling to room temperature, a hierarchical pore supported metal chloride catalyst is obtained;

[0079] (8) Multistage channel supported metal chloride catalyst is added into the first, second and third chlorination towers, the loading amount of the catalyst is 40% of the volume of the chlorination tower, and the service life of the catalyst is 6 months;

[0080] (9) The p-chloronitrobenzene raw material is transported into the first chlorination tower from the top of the tower and flows to the bottom of the tower, and the chlorine gas is bubbled 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, 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] (10) The chlorination liquid of the first chlorination tower overflows into the top of the second chlorination tower and flows to the bottom of the tower, and the chlorine gas is bubbled 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, 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;

[0082] (11) The chlorination liquid of the second chlorination tower overflows into the top of the third chlorination tower and flows to the bottom of the tower, and the chlorine gas is bubbled 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, 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 tower to the buffer tank;

[0083] (12) The chlorination liquid in the buffer tank is transported into the first deacidification kettle at a flow rate of 3 t / h, and compressed air is bubbled in at a temperature of 95°C to remove hydrogen chloride, the chlorination liquid in the first deacidification kettle overflows into the second deacidification kettle, and compressed air is further bubbled in at a temperature of 105°C to remove hydrogen chloride, and the deacidified chlorination liquid enters the crude product tank;

[0084] (13) The chlorination liquid in the crude product tank is transported into the 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°C, and the top temperature is controlled at 165°C, the p-chloronitrobenzene evaporated at the top is recovered and reused, the kettle material of the light component removal tower enters the 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°C, and the top temperature is controlled at 180°C, the tar is collected from the kettle of the heavy component removal tower, and the top material is crystallized and purified to obtain 3,4-dichloronitrobenzene.

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

[0086] Example 3

[0087] ​The continuous chlorination production process of 3,4-dichloronitrobenzene in the embodiment comprises the following steps:

[0088] (1) 120 parts of tetraethyl orthosilicate, 20 parts of block copolymer F127, 15 parts of polyurethane foam, 4 parts of (3-aminopropyl) triethoxysilane, 600 parts of anhydrous ethanol, 100 parts of deionized water, 25 parts of ferric chloride, 20 parts of zinc chloride, 5 parts of lanthanum chloride, 3 parts of cerium chloride, and 8 parts of acetylacetone are weighed according to parts by weight;

[0089] (2) The (3-aminopropyl) triethoxysilane is added to 1 / 3 of the anhydrous ethanol and stirred uniformly to obtain a treatment solution;

[0090] (3) The polyurethane foam is cut into small pieces of 5*5*5 mm, calcined at 400 DEG C for 3 h under nitrogen protection, and then placed in the treatment solution and soaked in a water bath at 40 DEG C for 24 h, and then taken out and dried to obtain a macroporous template;

[0091] (4) The tetraethyl orthosilicate is added to 1 / 3 of the anhydrous ethanol and mixed uniformly, a 10% hydrochloric acid solution is added dropwise to adjust the pH to 3, the block copolymer F127 and the macroporous template are added, and stirring is performed at a speed of 500 rpm under the condition of a water bath at 60 DEG C for 2 h, deionized water is added dropwise, and then the mixture is aged for 24 h and placed in a high-pressure reaction kettle and reacted at a temperature of 120 DEG C for 48 h, the reaction product is placed in a calcining furnace and heated to 450 DEG C at a rate of 2 DEG C / min, and then kept at this temperature for 6 h, and then cooled at room temperature to obtain a hierarchical pore silica carrier;

[0092] (5) The ferric chloride, zinc chloride, lanthanum chloride, cerium chloride, and acetylacetone are sequentially added to the remaining 1 / 3 of the anhydrous ethanol, and ultrasonic treatment is performed at a power of 400 W for 40 min to obtain an impregnation solution;

[0093] (6) The hierarchical pore silica carrier is preheated to 100 DEG C and vacuum dehydrated for 2 h, then placed in the impregnation solution and impregnated at a temperature of 50 DEG C for 8 h, and then sealed and aged at a temperature of 35 DEG C for 24 h, and then placed in an oven at 120 DEG C and dried for 4 h to obtain a catalyst precursor;

[0094] (7) The catalyst precursor is placed in a tube furnace, nitrogen protection is performed, heating is performed at a rate of 3 DEG C / min to 250 DEG C, then a chlorine gas-nitrogen mixed gas with a chlorine volume fraction of 15% is introduced, and then kept at this temperature for 8 h, then switched to dry nitrogen, and then cooled to 180 DEG C, then a hydrogen chloride gas with a volume fraction of 0.5% is introduced for treatment for 4 h, and then cooled at room temperature to obtain a hierarchical pore supported metal chloride catalyst;

[0095] (8) The hierarchical pore supported metal chloride catalyst is added to a primary chlorination tower, a secondary chlorination tower, and a tertiary chlorination tower, the loading amount of the catalyst is 50% of the volume of the chlorination tower, and the service life of the catalyst is 8 months.

[0096] (9) The p-chloronitrobenzene raw material is transported from the top of the first-stage chlorination tower to the tower and flows to the bottom, and chlorine gas is bubbled into the tower from the bottom of the first-stage chlorination tower at a flow rate of 0.6 t / h and flows to the top of the tower, the temperature of the first-stage chlorination tower is controlled at 80°C, and the pressure is -5 KPa 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;

[0097] (10) The chlorination liquid of the first-stage chlorination tower overflows into 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 0.4 t / h and flows to the top of the tower, the temperature of the second-stage chlorination tower is controlled at 90°C, and the pressure is -5 KPa 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;

[0098] (11) The chlorination liquid of the second-stage chlorination tower overflows into 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 0.2 t / h and flows to the top of the tower, the temperature of the third-stage chlorination tower is controlled at 100°C, and the pressure is -5 KPa 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, and the chlorination liquid overflows from the third-stage tower to the buffer tank;

[0099] (12) The chlorination liquid in the buffer tank is transported into the first-stage deacidification kettle at a flow rate of 4 t / h, and compressed air is bubbled in at a temperature of 100°C to remove hydrogen chloride, the chlorination liquid in the first-stage deacidification kettle overflows into the second-stage deacidification kettle, and compressed air is further bubbled in at a temperature of 110°C to remove hydrogen chloride, and the deacidified chlorination liquid enters the crude product tank;

[0100] (13) The chlorination liquid in the crude product tank is transported into the light component removal tower at a flow rate of 4.5 t / h, the kettle temperature of the light component removal tower is controlled at 80°C, and the top temperature is 170°C, p-chloronitrobenzene is distilled out of the top of the tower and recycled, the kettle material enters the heavy component removal tower at a flow rate of 3 t / h, the kettle temperature of the heavy component removal tower is controlled at 195°C, and the top temperature is 185°C, tar is produced from the kettle of the tower, and the top material is crystallized and purified to obtain 3,4-dichloronitrobenzene.

[0101] The 3,4-dichloronitrobenzene prepared in Example 3 was detected by liquid chromatography, and the specific results are shown in Table 1. Figure 3

[0102] Experimental Example

[0103] The products of Examples 1-3 were selected as samples, and appearance and component detection were carried out, including 3,4-dichloronitrobenzene purity, 2,5-dichloronitrobenzene content, and 2,3-dichloronitrobenzene content, and the specific detection results are shown in Table 1: ​

[0104] Table 1: detection results of examples 1~3

[0105]

[0106] From the examples in Table 1, it can be seen that the 3,4-dichloronitrobenzene prepared by the method of examples 1~3 has a purity of more than 99.5%, which shows that the metal chloride catalyst prepared by using the multi-level pore silica as the carrier can effectively improve the selectivity and anti-carbon deposition capacity of the catalyst, improve the catalytic performance and prolong the service life of the catalyst. At the same time, the preparation of the catalyst uses the template method combined with the sol-gel method, which can effectively realize the uniform distribution of the active components after impregnation. Finally, a special activation process is used to form active chlorine species by chlorine activation, which improves the initial activity of the catalyst and effectively improves the yield of the reaction product.

[0107] At the same time, the present application uses multi-stage chlorination tower to divide the chlorine feed and circulating stirring, the tower has a large height-diameter ratio, the chlorine stays in the tower for a long time during the rising process, and the catalyst packing is loaded in the chlorination tower, 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, 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, but uses a multi-level pore supported metal chloride catalyst, which not only prolongs the service life, but also reduces waste generation. The 3,4-dichloronitrobenzene production process provided by the present application has easy-to-obtain raw materials, simple operation, and is suitable for continuous industrial production, with high product purity, meeting the needs of various markets, resource utilization of by-products, and significant economic benefits.

[0108] Therefore, the catalyst, its preparation method and the continuous chlorination production process of 3,4-dichloronitrobenzene provided by the present application have good application effect and wide market prospect.

[0109] Based on the above ideal embodiments according to the present application, the related personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents of the specification, and must be determined by the scope of the claims.

Claims

1. A method for preparing a catalyst for the continuous chlorination production of 3,4-dichloronitrobenzene, characterized in that, The raw materials, by weight, include the following components: 100-120 parts tetraethyl orthosilicate, 10-20 parts block copolymer F127, 5-15 parts polyurethane foam, 2-4 parts (3-aminopropyl)triethoxysilane, 300-600 parts anhydrous ethanol, 50-100 parts deionized water, 15-25 parts ferric chloride, 10-20 parts zinc chloride, 2-5 parts lanthanum chloride, 1-3 parts cerium chloride, 3-8 parts acetylacetone; The method for preparing the catalyst includes the following steps: S1. Weigh each raw material component according to the weight percentage; S2. Add (3-aminopropyl)triethoxysilane to 1 / 3 of anhydrous ethanol and stir until homogeneous to obtain the treatment solution; S3. Cut the polyurethane foam into 5×5×5mm pieces, calcine them at 300~400℃ for 2~3h under nitrogen protection, cool them and place them in the treatment solution, soak them in a water bath at 30~40℃ for 12~24h, take them out and dry them to obtain the large-pore template. S4. Add tetraethyl orthosilicate to 1 / 3 anhydrous ethanol and mix well. Add 5%~10% hydrochloric acid by mass to adjust the pH to 2~3. Add block copolymer F127 and macroporous template. Stir at 300~500 rpm for 1~2 hours in a water bath at 40~60℃. Slowly add deionized water. After aging for 12~24 hours, place in a high-pressure reactor and react at 100~120℃ for 24~48 hours. Place the reactants in a calcination furnace and heat to 350~450℃ at a rate of 1~2℃ / min. Hold for 4~6 hours and cool at room temperature to obtain a multi-level porous silica carrier. S5. Add ferric chloride, zinc chloride, lanthanum chloride, cerium chloride, and acetylacetone sequentially to the remaining 1 / 3 of anhydrous ethanol, and sonicate at 200-400W for 20-40 minutes to obtain the impregnation solution. S6. After preheating the multi-level porous silica support to 80~100℃, vacuum dehydrate it for 1~2h, place it in the impregnation solution and impregnate it at 30~50℃ for 4~8h, then seal and age it at 25~35℃ for 12~24h, and dry it in an oven at 80~120℃ for 2~4h to obtain the catalyst precursor. S7. Place the catalyst precursor in a tube furnace, purge with nitrogen for protection, and heat to 200-250°C at a rate of 2-3°C / min. Then purge with a chlorine-nitrogen mixture containing 5%-15% chlorine gas and maintain the temperature for activation for 4-8 hours. Then switch to dry nitrogen and cool to 150-180°C. Purge with hydrogen chloride gas containing 0.1%-0.5% hydrogen chloride gas for 2-4 hours and cool to room temperature to obtain a multi-level porous supported metal chloride catalyst.

2. A continuous chlorination process for producing 3,4-dichloronitrobenzene, characterized in that, Includes the following steps: (1) Add multi-stage porous supported metal chloride 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) 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. (6) 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 multi-level porous supported metal chloride catalyst is the catalyst prepared by the preparation method described in claim 1.

3. The continuous chlorination production process for 3,4-dichloronitrobenzene according to claim 2, characterized in that, In step (1), the loading amount of the multi-channel supported metal chloride catalyst in the primary chlorination tower, secondary chlorination tower and tertiary chlorination tower is 30% to 50% of the volume of the chlorination tower, and the service life of the supported metal chloride catalyst is 4 to 8 months.

4. The continuous chlorination production process for 3,4-dichloronitrobenzene 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 continuous chlorination production process for 3,4-dichloronitrobenzene 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 continuous chlorination production process for 3,4-dichloronitrobenzene 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 continuous chlorination production process for 3,4-dichloronitrobenzene according to claim 2, characterized in that, In step (5), the flow rate of the chlorinated liquid in the buffer tank to the primary deacidification reactor is 2~4t / h.

8. The continuous chlorination production process for 3,4-dichloronitrobenzene according to claim 2, characterized in that, In step (6), the flow rate of chlorinated liquid in the crude product tank to the light product removal tower is 2.5~4.5t / h, and the flow rate of material from the bottom of the tower to the heavy product removal tower is 1.5~3t / h.

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