Preparation method of 2-amino-4-nitrophenol

Abstract

The invention discloses a preparation method of 2-amino-4-nitrophenol, belongs to the technical field of 2-amino-4-nitrophenol processing, and is used for solving the technical problems that in the prior art, the difficulty of recovering 2, 4-dinitrophenol from disperse blue wastewater is high, and the purity and the yield of 2-amino-4-nitrophenol need to be further improved. The method comprises the following steps: adding disperse blue production wastewater into a reaction kettle, stirring, and adding inorganic acid into the reaction kettle; according to the present invention, the adsorbent microspheres are prepared to adsorb the 2, 4-dinitrophenol in the disperse blue production wastewater, such that the process for recovering the 2, 4-dinitrophenol from the disperse blue wastewater is simplified, the purity and the regeneration rate of the regenerated 2, 4-dinitrophenol are improved, the composition of the catalyst solution and the reaction post-treatment method are optimized, and the 2, 4-dinitrophenol regeneration efficiency is improved. And the 2-amino-4-nitrophenol with high purity and high yield is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of 2-amino-4-nitrophenol processing, and in particular to a method for preparing 2-amino-4-nitrophenol. Background Art

[0002] 2-Amino-4-nitrophenol is an important organic compound that plays a vital role in the synthesis of dyes, pesticides, medicines and their intermediates. With the continuous development of the chemical industry, the demand for 2-amino-4-nitrophenol is increasing.

[0003] In the prior art, a Chinese invention patent with publication number CN101519249A discloses a method for treating and recovering hydrolysis wastewater in the disperse blue production process: A) adjusting the pH value of the hydrolysis wastewater generated in the disperse blue production process to 2-3 and filtering it, and the filter cake is dried to obtain a crude 2,4-dinitrophenol product with a purity of more than 93.5%; B) passing the filtrate through a styrene-based macroporous adsorption resin at 10-50°C and a flow rate of 0.5-4.0BV / h (BV is the resin bed volume) adsorption tower; C) using sodium hydroxide and water with a mass concentration of 4%-8% as desorbents to desorb and regenerate the macroporous resin adsorbed with 2,4-dinitrophenol, the desorption temperature is 40-90°C, and the flow rate of the desorbent is 0.5-2.0BV / h; D) using sulfuric acid with a concentration of 98%, adjusting the pH of the desorbed eluate to 2-3, filtering, drying, and recovering the crude 2,4-dinitrophenol with a purity of more than 93%, and performing a cyclic operation of step D) together with the filtrate of this batch of eluate and the next batch of eluate obtained in step C).

[0004] The Chinese invention patent with publication number CN109970581A discloses a production process of 2-amino-4-nitrophenol, comprising the following steps: a) hydrolysis of dinitrochlorobenzene, b) reduction of 2,4-dinitrophenol sodium, and c) preparation of 2-amino-4-nitrophenol, wherein liquid sodium hydrosulfide with a content of 35-40wt% is used as a reducing agent, which can improve the reduction effect of sodium 2,4-dinitrophenol, thereby improving the yield and purity of 2,4-dinitrophenol, and on the other hand, it is safer, lower in cost and easier to store than sodium polysulfides such as sulfur and alkali sulfide, thereby improving production safety.

[0005] However, the prior art is relatively complicated for recovering and preparing 2,4-dinitrophenol from disperse blue production wastewater. The 2,4-dinitrophenol recovered from the wastewater has low purity and poor yield, which makes it difficult to recover and reuse 2,4-dinitrophenol in disperse blue wastewater. In addition, when 2,4-dinitrophenol is reduced to prepare 2-amino-4-nitrophenol by using sodium hydrosulfide as a catalyst in the prior art, the purity and yield of 2-amino-4-nitrophenol need to be further improved due to the influence of the catalyst and post-treatment process.

[0006] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing 2-amino-4-nitrophenol, which is used to solve the technical problems in the prior art that 2,4-dinitrophenol is difficult to recover from dispersed blue wastewater and the purity and yield of 2-amino-4-nitrophenol need to be further improved.

[0008] The purpose of the present invention can be achieved by the following technical scheme: A method for preparing 2-amino-4-nitrophenol comprises the following steps:

[0009] S1. Add disperse blue production wastewater into the reactor and stir, add inorganic acid into the reactor, adjust the system pH to 3-4, add adsorbent microspheres into the reactor, increase the temperature of the reactor to 50-60°C, keep warm and stir for 2-3h, and post-treat to obtain adsorption-saturated microspheres;

[0010] The principle of adsorbent microspheres adsorbing 2,4-dinitrophenol is:

[0011] The amino, hydroxyl and other functional groups on the polymer chains of the adsorbent microspheres and the negatively charged surface of montmorillonite itself provide abundant active sites for the adsorption process, enabling the adsorbent microspheres to hydrogen bond with the nitro, hydroxyl and other functional groups in the 2,4-dinitrophenol molecules, thereby loading 2,4-dinitrophenol on the adsorbent microspheres in the form of chemical adsorption to prepare adsorption-saturated microspheres.

[0012] S2, desorbing and purifying the adsorption-saturated microspheres to obtain 2,4-dinitrophenol;

[0013] S3, adding 2,4-dinitrophenol and deionized water into a reactor and stirring, raising the temperature of the reactor to 90-95° C., dropping the catalyst solution into the reactor, keeping the temperature for reaction for 50-60 min, and post-treating to obtain a crude product of 2-amino-4-nitrophenol;

[0014] The synthetic reaction formula of 2-amino-4-nitrophenol is:

[0015]

[0016] The synthetic reaction mechanism of 2-amino-4-nitrophenol is:

[0017] Under alkaline conditions, the hydrosulfide ion acts as a reducing agent to attack a nitro group in the 2,4-dinitrophenol molecule. The nitrogen atom in the nitro group accepts the electrons provided by the hydrosulfide ion, causing the nitro group to be reduced to an amino group. In the 2,4-dinitrophenol molecule, since both the hydroxyl group and the nitro group are connected to the benzene ring, and the oxygen atom of the hydroxyl group and the nitrogen atom in the nitro group both carry partial negative charges, there is an electrostatic repulsion between them. When the nitro group is close to the hydroxyl group, this electrostatic repulsion reduces the electron cloud density of the nitro group, making it more susceptible to attack by nucleophiles, and then reduced to prepare 2-amino-4-nitrophenol.

[0018] S4. Add crude 2-amino-4-nitrophenol and deionized water into a reactor and stir. The temperature of the reactor is raised to 70-80° C. and stirred until the system is dissolved. The temperature of the reactor is slowly lowered to 10-15° C. and post-treated to obtain 2-amino-4-nitrophenol.

[0019] Furthermore, in step S1, the inorganic acid is any one of hydrochloric acid, sulfuric acid, and nitric acid, the dosage ratio of the disperse blue production wastewater and the adsorbent microspheres is 100mL:6-8g, and the post-treatment includes: after the stirring is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed twice with purified water and then dried to obtain adsorption-saturated microspheres.

[0020] Further, in step S2, desorption and purification include the following steps:

[0021] A1. Add the adsorption-saturated microspheres and analytical solution into a reactor and stir. Raise the temperature of the reactor to 60-65°C, keep warm and stir for 30-50 minutes, and perform post-treatment to obtain a crude 2,4-dinitrophenol product.

[0022] A2. Add crude 2,4-dinitrophenol and xylene into a reactor and stir until the system is dissolved. Add activated carbon and purified water into the reactor. Raise the temperature of the reactor to 95-105° C. and keep the temperature for 50-60 min. Post-treat to obtain 2,4-dinitrophenol.

[0023] Further, in step A1, the adsorption saturated microspheres and the analytical solution are used in an amount ratio of 1g:7mL, the analytical solution is composed of anhydrous ethanol and 0.1mol / L sodium hydroxide solution in a volume ratio of 4:1, and the post-treatment includes: after the reaction is completed, suction filtration, washing the filter cake twice with the analytical solution and then washing it with purified water until neutral, combining the filtrate and the washing solution to obtain a mixed solution, transferring the mixed solution to a rotary evaporator with a water bath temperature of 70-80°C, and removing the solvent under reduced pressure to obtain crude 2,4-dinitrophenol product; in step A2, the amount ratio of the crude 2,4-dinitrophenol, xylene, activated carbon and purified water is 10g:100mL:1g:20mL, and the post-treatment comprises: after the reaction is completed, filtering while hot, transferring the filtrate to a reactor, adding sodium carbonate to the reactor until the water phase is saturated, stirring until the temperature of the reactor drops to room temperature and then standing to separate the water phase, the organic phase is dried in a drying oven and transferred to a rotary evaporator with a water bath temperature of 70-75°C, and distilling off xylene under reduced pressure to obtain 2,4-dinitrophenol.

[0024] Further, in step S3, the amount ratio of the 2,4-dinitrophenol, deionized water and catalyst solution is 1g:10mL:1mL, the catalyst solution is composed of sodium hydrosulfide and 2-3mol / L sodium hydroxide solution in an amount ratio of 1g:5mL, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is reduced to 10-15°C, filtered, the filter cake is washed twice with 10-15°C purified water and then dried, the filter cake and deionized water are added to the reactor in an amount ratio of 1g:7mL and stirred, the temperature of the reactor is increased to 80°C, and stirred until the system dissolve, add hydrochloric acid to the reactor, adjust the system pH to 4.6-5, reduce the temperature of the reactor to 20-25°C, filter by suction, transfer the filter cake to a drying oven at a temperature of 50-60°C, and vacuum dry to constant weight to obtain crude 2-amino-4-nitrophenol; in step S4, the amount ratio of the crude 2-amino-4-nitrophenol to deionized water is 1g:6mL, and the post-treatment includes: after the reaction is completed, filter by suction, transfer the filter cake to a drying oven at a temperature of 50-60°C, and vacuum dry to constant weight to obtain 2-amino-4-nitrophenol.

[0025] Furthermore, the preparation method of the adsorbent microspheres is: toluene and polyvinyl alcohol are added to a nitrogen-protected reactor and stirred until the system is dissolved, modified montmorillonite, styrene, 3-butene-1-amine and initiator are added to the reactor, ultrasonic dispersion is performed for 30-50 minutes, the temperature of the reactor is increased to reflux, the reaction is kept warm for 10-12 hours, and the adsorbent microspheres are obtained by post-treatment.

[0026] The synthetic reaction principle of adsorbent microspheres is:

[0027] During the reaction, the olefin double bonds on the surface of the modified montmorillonite provide active sites for the subsequent polymerization reaction. Styrene and 3-butene-1-amine are used as monomers, and azobisisobutyronitrile is used as an initiator to initiate the polymerization reaction to form polymer microspheres wrapped with montmorillonite particles. During the reaction, polyvinyl alcohol is used as a dispersion stabilizer, and the polymer is evenly dispersed in the reaction system to form microsphere particles. After solidification and molding, the polyvinyl alcohol molecules in the microsphere particles are removed through subsequent high-temperature water treatment to form adsorbent microspheres with a porous structure.

[0028] Furthermore, the amount ratio of toluene, polyvinyl alcohol, modified montmorillonite, styrene, 3-butene-1-amine and initiator is 100mL:3g:5g:20g:4g:0.1g, the initiator is azobisisobutyronitrile, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, the filter cake and purified water are added to the reactor in a weight ratio of 1:10 and stirred, the temperature of the reactor is increased to 75-85°C, the heat treatment is carried out for 40-60min, filtered while hot, the filter cake is washed with purified water 2-3 times and then dried, the filter cake is transferred to a drying oven at a temperature of 70-80°C, and vacuum dried to constant weight to obtain adsorbent microspheres.

[0029] Further, the modified montmorillonite is processed by the following steps:

[0030] B1, adding montmorillonite and sodium hydroxide into a ball mill, and ball milling for 40-50 minutes to obtain montmorillonite mixed powder;

[0031] B2, adding the montmorillonite mixed powder into a nitrogen-protected tubular furnace, heating the tubular furnace to 320-360° C. at a heating rate of 5-8° C. / min, and heat preservation for 40-60 min, and post-treating to obtain pretreated montmorillonite;

[0032] B3, adding the pretreated montmorillonite and deionized water into a reactor, ultrasonically dispersing for 30-50 min at room temperature, adding the polyacrylamide solution into the reactor, keeping the temperature and ultrasonically dispersing for 10-12 h, and post-treating to obtain the loaded montmorillonite;

[0033] B4. Add the loaded montmorillonite, anhydrous ethanol and vinyl triethoxysilane into a reactor and stir. Increase the temperature of the reactor to 50-60° C., add a catalyst into the reactor, keep the temperature for 4-6 hours, and perform post-treatment to obtain modified montmorillonite.

[0034] The synthetic reaction principle of modified montmorillonite is:

[0035] After the montmorillonite and sodium hydroxide are mixed by ball milling, the sodium hydroxide promotes the silicate anions on the montmorillonite molecules to undergo a dehydroxylation reaction at high temperature to form a stable silicate structure, and then the sodium hydroxide and soluble silicate are removed by water washing to form a pretreated montmorillonite with a porous structure. The polyacrylamide and the pretreated montmorillonite are uniformly dispersed by ultrasonic dispersion, and the amide groups on the polyacrylamide molecular chain can interact with the hydroxyl groups and silicon oxygen bonds on the surface of the pretreated montmorillonite through hydrogen bonds, van der Waals forces, etc. to form an intercalation effect, and the loaded attapulgite is prepared. Under alkaline conditions, the triethoxysilane on the vinyltriethoxysilane molecule is hydrolyzed to form silanol groups, which undergo a condensation reaction with the active groups on the surface of the loaded montmorillonite molecules to form a large number of unsaturated olefin double bond modifications on the surface of the loaded montmorillonite, and the modified montmorillonite is prepared.

[0036] Further, in step B1, the weight ratio of the montmorillonite to sodium hydroxide is 10:3-4; in step B2, the post-treatment includes: after the reaction is completed, the temperature of the tube furnace is reduced to room temperature, the material is discharged to obtain a calcined powder, the calcined powder is washed with purified water until it is neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 70-80°C, and vacuum dried to constant weight to obtain a pretreated montmorillonite; in step B3, the amount ratio of the pretreated montmorillonite, deionized water and polyacrylamide solution is 5g:50mL:5g, the polyacrylamide solution is composed of polyacrylamide and deionized water in a weight ratio of 1:10, and the post-treatment includes: the reaction After completion, the filter cake is filtered, washed twice with purified water and then dried, and the filter cake is transferred to a drying oven at a temperature of 70-80°C, and the weight is constant during vacuum drying to obtain loaded montmorillonite; in step B4, the amount ratio of the loaded montmorillonite, anhydrous ethanol, vinyltriethoxysilane and catalyst is 5g:50mL:2g:10mL, and the catalyst is 0.1-0.2mol / L sodium hydroxide solution. The post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, the filter cake is washed with purified water until neutral and then dried, and the filter cake is transferred to a drying oven at a temperature of 70-80°C, and vacuum dried to constant weight to obtain modified montmorillonite.

[0037] The present invention has the following beneficial effects:

[0038] 1. A method for preparing 2-amino-4-nitrophenol of the present invention comprises the following steps: preparing adsorbent microspheres, optimizing adsorption conditions, adsorbing and regenerating 2,4-dinitrophenol in disperse blue production wastewater, and then purifying the 2,4-dinitrophenol to prepare high-purity 2,4-dinitrophenol, improving the recovery rate of 2,4-dinitrophenol in disperse blue production wastewater, reducing the difficulty of recovering and reusing 2,4-dinitrophenol from disperse blue wastewater, optimizing the catalyst solution to combine sodium hydroxide and sodium persulfate, and adjusting the pH of the reaction system with an inorganic acid after the reaction is completed, thereby reducing the impurity content of the 2-amino-4-nitrophenol, and then preparing high-purity and high-yield 2-amino-4-nitrophenol by recrystallization.

[0039] 2. A method for preparing 2-amino-4-nitrophenol of the present invention comprises the following steps: using the olefin double bonds on the surface of the porous modified montmorillonite loaded with polyacrylamide as reaction sites to construct an adsorbent microsphere with a three-dimensional network structure; the high specific surface area and porosity of the adsorbent microsphere provide abundant loading space for 2,4-dinitrophenol loading; under acidic conditions, hydrogen bonds are formed between the hydroxyl groups or amino groups on the surface of the adsorbent microsphere and the phenolic hydroxyl groups in the 2,4-dinitrophenol molecules, thereby enhancing the interaction between the adsorbent microsphere and the 2,4-dinitrophenol molecules and promoting the adsorption of 2,4-dinitrophenol. The attachment rate and selectivity are improved, thereby improving the adsorption rate of the adsorbent microspheres on 2,4-dinitrophenol molecules in the dispersed blue production wastewater. After the adsorbent microspheres are desorbed by an alkaline ethanol solution, the crude 2,4-dinitrophenol is purified by a mixed system consisting of xylene, water and activated carbon to remove pigments and impurities in the solution and improve the purity of the product. The acidic impurities in the solution are neutralized by sodium carbonate to further improve the purity of the product and obtain high-purity 2,4-dinitrophenol, thereby obtaining a high-purity product in the subsequent preparation of 2-amino-4-nitrophenol. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides a method for preparing adsorbent microspheres for regeneration of 2,4-dinitrophenol, comprising the following steps:

[0043] A1. Montmorillonite pretreatment

[0044] Montmorillonite and sodium hydroxide were added into a ball mill at a weight ratio of 10:3, and after ball milling for 40 minutes, the mixture was passed through a 300-mesh sieve to obtain a montmorillonite mixed powder;

[0045] The montmorillonite mixed powder was added into a nitrogen-protected tubular furnace, the temperature of the tubular furnace was increased to 320°C at a heating rate of 5°C / min, and the temperature was kept for 40 minutes. After the reaction was completed, the temperature of the tubular furnace was lowered to room temperature, the material was discharged, and the calcined powder was obtained. The calcined powder was washed with purified water until it was neutral and then dried. The filter cake was transferred to a drying oven at a temperature of 70°C and vacuum dried to constant weight to obtain pretreated montmorillonite.

[0046] A2. Preparation of loaded montmorillonite

[0047] Mix polyacrylamide and deionized water in a weight ratio of 1:10 to obtain a polyacrylamide solution;

[0048] Weigh: 500 g of pretreated montmorillonite and 5000 mL of deionized water are added to the reactor, and ultrasonic dispersion is performed for 30 minutes at room temperature. 500 g of polyacrylamide solution is added to the reactor, and the reaction is kept warm and ultrasonic for 10 hours. After the reaction is completed, the filter is filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a dryer at a temperature of 70°C, and the weight is constant during vacuum drying to obtain loaded montmorillonite.

[0049] A3. Preparation of modified montmorillonite

[0050] Weigh: 500 g of loaded montmorillonite, 5000 mL of anhydrous ethanol and 200 g of vinyltriethoxysilane are added to a reactor and stirred. The temperature of the reactor is raised to 50°C, 1000 mL of 0.1 mol / L sodium hydroxide solution is added to the reactor, and the reaction is kept warm for 4 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 70°C and vacuum dried to constant weight to obtain modified montmorillonite.

[0051] A4. Preparation of adsorbent microspheres

[0052] Weigh: 2000mL of toluene and 60g of polyvinyl alcohol are added to a nitrogen-protected reactor and stirred until the system is dissolved. 100g of modified montmorillonite, 400g of styrene, 80g of 3-butene-1-amine and 2g of azobisisobutyronitrile are added to the reactor, and ultrasonic dispersion is performed for 30min. The temperature of the reactor is raised to reflux of the system and the reaction is kept warm for 10h. After the reaction is completed, the temperature of the reactor is lowered to room temperature and filtered. The filter cake and purified water are added to the reactor in a weight ratio of 1:10 and stirred. The temperature of the reactor is raised to 75°C and kept warm for 40min. The filter cake is filtered while hot, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 70°C and vacuum dried to constant weight to obtain adsorbent microspheres.

[0053] Example 2

[0054] This embodiment provides a method for preparing adsorbent microspheres for regeneration of 2,4-dinitrophenol, comprising the following steps:

[0055] A1. Montmorillonite pretreatment

[0056] Montmorillonite and sodium hydroxide were added into a ball mill in a weight ratio of 10:3.5, and after ball milling for 45 minutes, the mixture was passed through a 300-mesh sieve to obtain a montmorillonite mixed powder;

[0057] The montmorillonite mixed powder was added into a nitrogen-protected tubular furnace, the temperature of the tubular furnace was increased to 340°C at a heating rate of 7°C / min, and the temperature was kept for 50 minutes. After the reaction was completed, the temperature of the tubular furnace was lowered to room temperature, the material was discharged, and the calcined powder was obtained. The calcined powder was washed with purified water until it was neutral and then dried. The filter cake was transferred to a drying oven at a temperature of 75°C and vacuum dried to constant weight to obtain pretreated montmorillonite.

[0058] A2. Preparation of loaded montmorillonite

[0059] Mix polyacrylamide and deionized water in a weight ratio of 1:10 to obtain a polyacrylamide solution;

[0060] Weigh: 500 g of pretreated montmorillonite and 5000 mL of deionized water are added to the reactor, and ultrasonic dispersion is performed for 40 min at room temperature. 500 g of polyacrylamide solution is added to the reactor, and the reaction is kept ultrasonic for 11 h. After the reaction is completed, the filter is filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying machine at a temperature of 75°C, and the weight is constant during vacuum drying to obtain loaded montmorillonite.

[0061] A3. Preparation of modified montmorillonite

[0062] Weigh: 500 g of loaded montmorillonite, 5000 mL of anhydrous ethanol and 200 g of vinyltriethoxysilane are added to a reactor and stirred. The temperature of the reactor is raised to 55°C, 1000 mL of 0.15 mol / L sodium hydroxide solution is added to the reactor, and the reaction is kept warm for 5 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and vacuum dried to constant weight to obtain modified montmorillonite.

[0063] A4. Preparation of adsorbent microspheres

[0064] Weigh: 2000mL of toluene and 60g of polyvinyl alcohol are added to a nitrogen-protected reactor and stirred until the system is dissolved. 100g of modified montmorillonite, 400g of styrene, 80g of 3-butene-1-amine and 2g of azobisisobutyronitrile are added to the reactor, and ultrasonic dispersion is performed for 40min. The temperature of the reactor is raised to reflux of the system, and the reaction is kept warm for 11h. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake and purified water are added to the reactor in a weight ratio of 1:10 and stirred. The temperature of the reactor is raised to 80°C, and the heat treatment is carried out for 50min. The filter cake is filtered while hot, and the filter cake is washed 3 times with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and vacuum dried to constant weight to obtain adsorbent microspheres.

[0065] Example 3

[0066] This embodiment provides a method for preparing adsorbent microspheres for regeneration of 2,4-dinitrophenol, comprising the following steps:

[0067] A1. Montmorillonite pretreatment

[0068] Montmorillonite and sodium hydroxide were added into a ball mill at a weight ratio of 10:4, and after ball milling for 50 minutes, the mixture was passed through a 300-mesh sieve to obtain a montmorillonite mixed powder;

[0069] The montmorillonite mixed powder was added into a nitrogen-protected tubular furnace, the temperature of the tubular furnace was increased to 360°C at a heating rate of 8°C / min, and the temperature was kept for 60 minutes. After the reaction was completed, the temperature of the tubular furnace was lowered to room temperature, the material was discharged, and the calcined powder was obtained. The calcined powder was washed with purified water until it was neutral and then dried. The filter cake was transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain pretreated montmorillonite.

[0070] A2. Preparation of loaded montmorillonite

[0071] Mix polyacrylamide and deionized water in a weight ratio of 1:10 to obtain a polyacrylamide solution;

[0072] Weigh: 500 g of pretreated montmorillonite and 5000 mL of deionized water are added to the reactor, and ultrasonic dispersion is performed for 50 min at room temperature. 500 g of polyacrylamide solution is added to the reactor, and the reaction is kept ultrasonic for 12 h. After the reaction is completed, the filter is filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a dryer at a temperature of 80°C, and the weight is constant during vacuum drying to obtain loaded montmorillonite.

[0073] A3. Preparation of modified montmorillonite

[0074] Weigh: 500 g of loaded montmorillonite, 5000 mL of anhydrous ethanol and 200 g of vinyltriethoxysilane are added to a reactor and stirred. The temperature of the reactor is raised to 60°C, 1000 mL of 0.2 mol / L sodium hydroxide solution is added to the reactor, and the reaction is kept warm for 6 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain modified montmorillonite.

[0075] A4. Preparation of adsorbent microspheres

[0076] Weigh: 2000mL of toluene and 60g of polyvinyl alcohol are added to a nitrogen-protected reactor and stirred until the system is dissolved. 100g of modified montmorillonite, 400g of styrene, 80g of 3-butene-1-amine and 2g of azobisisobutyronitrile are added to the reactor, ultrasonic dispersion is performed for 50min, the temperature of the reactor is raised to reflux of the system, and the reaction is kept warm for 12h. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, the filter cake and purified water are added to the reactor in a weight ratio of 1:10 and stirred, the temperature of the reactor is raised to 85°C, and the heat treatment is carried out for 60min. Filter while hot, wash the filter cake with purified water 3 times and then dry it, transfer the filter cake to a drying oven at a temperature of 80°C, and vacuum dry it to constant weight to obtain adsorbent microspheres.

[0077] Example 4

[0078] This embodiment provides a method for preparing 2-amino-4-nitrophenol, comprising the following steps:

[0079] S1. Preparation of crude 2,4-dinitrophenol

[0080] Weigh: 5000 mL of disperse blue production wastewater was added to the reactor and stirred, hydrochloric acid was added to the reactor to adjust the system pH to 3, 300 g of the adsorbent microspheres prepared in Example 1 were added to the reactor, the reactor temperature was raised to 50° C., and the mixture was stirred for 2 h at the temperature, and the reactor temperature was lowered to room temperature, and the filter cake was filtered, and the filter cake was washed twice with purified water and then dried to obtain adsorption-saturated microspheres;

[0081] Anhydrous ethanol and 0.1 mol / L sodium hydroxide solution were mixed uniformly in a volume ratio of 4:1 to obtain a resolution solution;

[0082] The adsorption-saturated microspheres and analytical solution were added to the reactor at a ratio of 1 g:7 mL and stirred. The temperature of the reactor was raised to 60°C and stirred for 30 minutes. After the reaction was completed, the filter was filtered and the filter cake was washed twice with the analytical solution and then with purified water until neutral. The filtrate was combined with the washing solution to obtain a mixed solution, which was transferred to a rotary evaporator with a water bath temperature of 70°C, and the solvent was evaporated under reduced pressure to obtain a crude 2,4-dinitrophenol product.

[0083] S2. Preparation of 2,4-dinitrophenol

[0084] Weigh: crude 2,4-dinitrophenol and xylene are added to a reactor and stirred until the system is dissolved, activated carbon and purified water are added to the reactor, the temperature of the reactor is raised to 95°C, and the reactor is kept warm for 50 minutes. After the reaction is completed, it is filtered while hot, and the filtrate is transferred to the reactor, sodium carbonate is added to the reactor until the water phase is saturated, and the reactor is stirred until the temperature of the reactor drops to room temperature and then allowed to stand to separate the water phase. The organic phase is transferred to a rotary evaporator with a water bath temperature of 70°C after drying in a drying oven, and xylene is evaporated under reduced pressure to obtain 2,4-dinitrophenol, wherein the amount ratio of crude 2,4-dinitrophenol, xylene, activated carbon and purified water is 10g:100mL:1g:20mL.

[0085] S3. Preparation of crude 2-amino-4-nitrophenol

[0086] Sodium hydrosulfide and 2 mol / L sodium hydroxide solution were mixed uniformly at a dosage ratio of 1 g:5 mL to obtain a catalyst solution;

[0087] 2,4-dinitrophenol and deionized water were added to a reactor and stirred. The temperature of the reactor was increased to 90°C. The catalyst solution was added dropwise to the reactor and the reaction was kept warm for 50 minutes. After the reaction was completed, the temperature of the reactor was lowered to 10°C, and the filter cake was washed twice with 10°C purified water and then dried. The filter cake and deionized water were added to the reactor at a ratio of 1g:7mL and stirred. The temperature of the reactor was increased to 80°C and stirred until the system was dissolved. Hydrochloric acid was added to the reactor to adjust the pH of the system to 4.6. The temperature of the reactor was lowered to 20°C, and the filter cake was transferred to a drying oven at a temperature of 50°C and vacuum dried to constant weight to obtain crude 2-amino-4-nitrophenol, wherein the amount ratio of 2,4-dinitrophenol, deionized water and catalyst solution was 1g:10mL:1mL.

[0088] S4. Preparation of 2-amino-4-nitrophenol

[0089] The crude 2-amino-4-nitrophenol and deionized water were added to a reactor at a ratio of 1 g: 6 mL and stirred. The temperature of the reactor was raised to 70°C and stirred until the system was dissolved. The temperature of the reactor was slowly lowered to 10°C, filtered, and the filter cake was transferred to a drying oven at a temperature of 50°C and vacuum dried to constant weight to obtain 2-amino-4-nitrophenol.

[0090] Example 5

[0091] This embodiment provides a method for preparing 2-amino-4-nitrophenol, comprising the following steps:

[0092] S1. Preparation of crude 2,4-dinitrophenol

[0093] Weigh: 5000 mL of disperse blue production wastewater was added to the reactor and stirred, sulfuric acid was added to the reactor to adjust the system pH to 3.5, 350 g of the adsorbent microspheres prepared in Example 2 were added to the reactor, the reactor temperature was raised to 55° C., and the mixture was stirred for 2.5 h at room temperature. The reactor temperature was lowered to room temperature, and the filter cake was filtered, and the filter cake was washed twice with purified water and then dried to obtain adsorption-saturated microspheres;

[0094] Anhydrous ethanol and 0.1 mol / L sodium hydroxide solution were mixed uniformly in a volume ratio of 4:1 to obtain a resolution solution;

[0095] The adsorption-saturated microspheres and analytical solution were added to the reactor at a ratio of 1 g:7 mL and stirred. The temperature of the reactor was raised to 63°C and stirred for 40 minutes. After the reaction was completed, the filter was filtered and the filter cake was washed twice with the analytical solution and then with purified water until neutral. The filtrate was combined with the washing solution to obtain a mixed solution, which was transferred to a rotary evaporator with a water bath temperature of 75°C, and the solvent was evaporated under reduced pressure to obtain a crude 2,4-dinitrophenol product.

[0096] S2. Preparation of 2,4-dinitrophenol

[0097] Weigh: crude 2,4-dinitrophenol and xylene are added to a reactor and stirred until the system is dissolved, activated carbon and purified water are added to the reactor, the temperature of the reactor is raised to 100°C, and the reactor is kept warm for 55 minutes. After the reaction is completed, it is filtered while hot, and the filtrate is transferred to the reactor, sodium carbonate is added to the reactor until the water phase is saturated, and the reactor is stirred until the temperature of the reactor drops to room temperature and then allowed to stand to separate the water phase. The organic phase is transferred to a rotary evaporator with a water bath temperature of 73°C after drying in a drying oven, and xylene is evaporated under reduced pressure to obtain 2,4-dinitrophenol, wherein the amount ratio of crude 2,4-dinitrophenol, xylene, activated carbon and purified water is 10g:100mL:1g:20mL.

[0098] S3. Preparation of crude 2-amino-4-nitrophenol

[0099] Sodium hydrosulfide and 2.5 mol / L sodium hydroxide solution were mixed uniformly at a dosage ratio of 1 g:5 mL to obtain a catalyst solution;

[0100] 2,4-dinitrophenol and deionized water were added to a reactor and stirred. The temperature of the reactor was increased to 93°C. The catalyst solution was added dropwise to the reactor and the reaction was kept warm for 55 minutes. After the reaction was completed, the temperature of the reactor was lowered to 13°C and filtered. The filter cake was washed twice with 13°C purified water and then dried. The filter cake and deionized water were added to the reactor at a dosage ratio of 1g:7mL and stirred. The temperature of the reactor was increased to 80°C and stirred until the system was dissolved. Hydrochloric acid was added to the reactor to adjust the pH of the system to 4.8. The temperature of the reactor was lowered to 23°C and filtered. The filter cake was transferred to a drying oven at a temperature of 55°C and vacuum dried to constant weight to obtain crude 2-amino-4-nitrophenol, wherein the dosage ratio of 2,4-dinitrophenol, deionized water and catalyst solution was 1g:10mL:1mL.

[0101] S4. Preparation of 2-amino-4-nitrophenol

[0102] The crude 2-amino-4-nitrophenol and deionized water were added to a reactor at a ratio of 1 g: 6 mL and stirred. The temperature of the reactor was raised to 75° C. and stirred until the system was dissolved. The temperature of the reactor was slowly lowered to 13° C. and filtered. The filter cake was transferred to a drying oven at a temperature of 55° C. and vacuum dried to constant weight to obtain 2-amino-4-nitrophenol.

[0103] Example 6

[0104] This embodiment provides a method for preparing 2-amino-4-nitrophenol, comprising the following steps:

[0105] S1. Preparation of crude 2,4-dinitrophenol

[0106] Weigh: 5000 mL of disperse blue production wastewater was added to the reactor and stirred, nitric acid was added to the reactor, the pH of the system was adjusted to 4, 400 g of the adsorbent microspheres prepared in Example 3 were added to the reactor, the temperature of the reactor was raised to 60° C., and the mixture was stirred for 3 h. The temperature of the reactor was lowered to room temperature, and the mixture was filtered. The filter cake was washed twice with purified water and then dried to obtain adsorption-saturated microspheres;

[0107] Anhydrous ethanol and 0.1 mol / L sodium hydroxide solution were mixed uniformly in a volume ratio of 4:1 to obtain a resolution solution;

[0108] The adsorption-saturated microspheres and analytical solution were added to the reactor at a ratio of 1 g:7 mL and stirred. The temperature of the reactor was raised to 65°C and stirred for 50 minutes. After the reaction was completed, the filter was filtered and the filter cake was washed twice with the analytical solution and then with purified water until neutral. The filtrate was combined with the washing solution to obtain a mixed solution, which was transferred to a rotary evaporator with a water bath temperature of 80°C, and the solvent was evaporated under reduced pressure to obtain a crude 2,4-dinitrophenol product.

[0109] S2. Preparation of 2,4-dinitrophenol

[0110] Weigh: crude 2,4-dinitrophenol and xylene are added to a reactor and stirred until the system is dissolved, activated carbon and purified water are added to the reactor, the temperature of the reactor is raised to 105°C, and the reactor is kept warm for 60 minutes. After the reaction is completed, it is filtered while hot, and the filtrate is transferred to the reactor, sodium carbonate is added to the reactor until the water phase is saturated, and the reactor is stirred until the temperature of the reactor drops to room temperature and then allowed to stand to separate the water phase. The organic phase is transferred to a rotary evaporator with a water bath temperature of 75°C after drying in a drying oven, and xylene is evaporated under reduced pressure to obtain 2,4-dinitrophenol, wherein the amount ratio of crude 2,4-dinitrophenol, xylene, activated carbon and purified water is 10g:100mL:1g:20mL.

[0111] S3. Preparation of crude 2-amino-4-nitrophenol

[0112] Sodium hydrosulfide and 3 mol / L sodium hydroxide solution were mixed uniformly at a dosage ratio of 1 g:5 mL to obtain a catalyst solution;

[0113] 2,4-dinitrophenol and deionized water were added to a reactor and stirred. The temperature of the reactor was increased to 95°C. The catalyst solution was added dropwise to the reactor and the reaction was kept warm for 60 minutes. After the reaction was completed, the temperature of the reactor was lowered to 15°C and filtered. The filter cake was washed twice with 15°C purified water and then dried. The filter cake and deionized water were added to the reactor at a dosage ratio of 1g:7mL and stirred. The temperature of the reactor was increased to 80°C and stirred until the system was dissolved. Hydrochloric acid was added to the reactor to adjust the pH of the system to 5. The temperature of the reactor was lowered to 25°C and filtered. The filter cake was transferred to a drying oven at a temperature of 60°C and vacuum dried to constant weight to obtain crude 2-amino-4-nitrophenol, wherein the dosage ratio of 2,4-dinitrophenol, deionized water and catalyst solution was 1g:10mL:1mL.

[0114] S4. Preparation of 2-amino-4-nitrophenol

[0115] The crude 2-amino-4-nitrophenol and deionized water were added to a reactor at a ratio of 1 g: 6 mL and stirred. The temperature of the reactor was raised to 80°C and stirred until the system was dissolved. The temperature of the reactor was slowly lowered to 15°C, filtered, and the filter cake was transferred to a drying oven at a temperature of 60°C and vacuum dried to constant weight to obtain 2-amino-4-nitrophenol.

[0116] Comparative Example 1

[0117] The difference between this comparative example and Example 6 is that, during the preparation process of the adsorbent microspheres prepared in Example 3, the pretreated montmorillonite in step A1 replaces the modified montmorillonite in step A3.

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 6 is that, during the preparation process of the adsorbent microspheres prepared in Example 3, the montmorillonite in step A1 is used to replace the modified montmorillonite in step A3.

[0120] Comparative Example 3

[0121] The difference between this comparative example and Example 6 is that no inorganic acid is added to the disperse blue production wastewater in step S1 to adjust the pH.

[0122] Comparative Example 4

[0123] The difference between this comparative example and Example 6 is that purified water and sodium carbonate are not added in step S2.

[0124] Comparative Example 5

[0125] The difference between this comparative example and Example 6 is that in step S3, hydrochloric acid is not added after the reaction is completed.

[0126] Performance Test:

[0127] The purity of the 2-amino-4-nitrophenol samples prepared in Examples 4-6 and Comparative Examples 1-5 was tested with reference to the standard GB / T 21887-2008 "2-amino-4-nitrophenol";

[0128] The purity of the 2,4-dinitrophenol samples used in Examples 4-6 and Comparative Examples 1-5 was tested with reference to the standard GB / T 21886-2008 "2,4-dinitrophenol";

[0129] According to the formula The recovery rate of the 2,4-dinitrophenol samples used in Examples 4-6 and Comparative Examples 1-5 was tested. In the formula, M 1 is the weight of 2,4-dinitrophenol, W 1 is the purity of 2,4-dinitrophenol, V is the volume of disperse blue production wastewater, W 2 To disperse the content of 2,4-dinitrophenol in blue wastewater;

[0130] According to the formula The yield of 2-amino-4-nitrophenol in Examples 4-6 and Comparative Examples 1-5 was calculated, where m 1 is the mass of 2-amino-4-nitrophenol, w 1 is the purity of 2-amino-4-nitrophenol, M 1 is the molecular weight of 2-amino-4-nitrophenol, m 2 is the mass of 2,4-dinitrophenol, w 2 is the purity of 2,4-dinitrophenol, M 2is the molecular weight of 2,4-dinitrophenol. The specific test results are shown in Table 1 below.

[0131] Table 1-Performance test data of the sample

[0132]

[0133] Data Analysis:

[0134] Comparative analysis of the data in Table 1 above shows that the recovery rate of 2,4-dinitrophenol in disperse blue production wastewater is 87.9%, the recovery purity of 2,4-dinitrophenol reaches 98.8%, the purity of the prepared 2-amino-4-nitrophenol reaches 99.6%, and the yield of 2-amino-4-nitrophenol reaches 74.1%. All performance data are better than those of the comparative example;

[0135] Explanation analysis:

[0136] The present application prepares adsorbent microspheres to adsorb 2,4-dinitrophenol in disperse blue production wastewater, which not only simplifies the process of recovering 2,4-dinitrophenol from disperse blue wastewater and improves the purity and regeneration rate of regenerated 2,4-dinitrophenol, but also optimizes the composition of the catalyst solution and the post-treatment method of the reaction to prepare high-purity and high-yield 2-amino-4-nitrophenol.

[0137] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0138] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0139] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing 2-amino-4-nitrophenol, characterized in that: The following steps are involved: S1. Add disperse blue production wastewater into the reactor and stir, add inorganic acid into the reactor, adjust the system pH to 3-4, add adsorbent microspheres into the reactor, increase the temperature of the reactor to 50-60°C, keep warm and stir for 2-3h, and post-treat to obtain adsorption-saturated microspheres; S2, desorbing and purifying the adsorption-saturated microspheres to obtain 2,4-dinitrophenol; S3, adding 2,4-dinitrophenol and deionized water into a reactor and stirring, raising the temperature of the reactor to 90-95° C., dropping the catalyst solution into the reactor, keeping the temperature for reaction for 50-60 min, and post-treating to obtain a crude product of 2-amino-4-nitrophenol; S4. Add crude 2-amino-4-nitrophenol and deionized water into a reactor and stir. The temperature of the reactor is raised to 70-80° C. and stirred until the system is dissolved. The temperature of the reactor is slowly lowered to 10-15° C. and post-treated to obtain 2-amino-4-nitrophenol.

2. A method for preparing 2-amino-4-nitrophenol according to claim 1, characterized in that: In step S1, the inorganic acid is any one of hydrochloric acid, sulfuric acid, and nitric acid, and the dosage ratio of the disperse blue production wastewater and the adsorbent microspheres is 100mL:6-8g.

3. A method for preparing 2-amino-4-nitrophenol according to claim 1, characterized in that: In step S2, desorption and purification include the following steps: A1. Add the adsorption-saturated microspheres and analytical solution into a reactor and stir. Raise the temperature of the reactor to 60-65°C, keep warm and stir for 30-50 minutes, and perform post-treatment to obtain a crude 2,4-dinitrophenol product. A2. Add crude 2,4-dinitrophenol and xylene into a reactor and stir until the system is dissolved. Add activated carbon and purified water into the reactor. Raise the temperature of the reactor to 95-105° C. and keep the temperature for 50-60 min. Post-treat to obtain 2,4-dinitrophenol.

4. A method for preparing 2-amino-4-nitrophenol according to claim 3, characterized in that: In step A1, the amount ratio of the adsorption-saturated microspheres and the analytical solution is 1 g:7 mL, and the analytical solution is composed of anhydrous ethanol and 0.1 mol / L sodium hydroxide solution in a volume ratio of 4:1; in step A2, the amount ratio of the crude 2,4-dinitrophenol, xylene, activated carbon and purified water is 10 g:100 mL:1 g:20 mL.

5. A method for preparing 2-amino-4-nitrophenol according to claim 1, characterized in that: In step S3, the dosage ratio of the 2,4-dinitrophenol, deionized water and catalyst solution is 1 g:10 mL:1 mL, and the catalyst solution is composed of sodium hydrosulfide and 2-3 mol / L sodium hydroxide solution in a dosage ratio of 1 g:5 mL; in step S4, the dosage ratio of the crude 2-amino-4-nitrophenol and deionized water is 1 g:6 mL.

6. A method for preparing 2-amino-4-nitrophenol according to claim 1, characterized in that: The preparation method of the adsorbent microspheres is as follows: toluene and polyvinyl alcohol are added into a nitrogen-protected reactor and stirred until the system is dissolved, modified montmorillonite, styrene, 3-butene-1-amine and an initiator are added into the reactor, ultrasonic dispersion is performed for 30-50 minutes, the temperature of the reactor is increased to reflux the system, the reaction is kept warm for 10-12 hours, and the adsorbent microspheres are obtained by post-processing.

7. A method for preparing 2-amino-4-nitrophenol according to claim 6, characterized in that: The dosage ratio of the toluene, polyvinyl alcohol, modified montmorillonite, styrene, 3-butene-1-amine and initiator is 100 mL: 3 g: 5 g: 20 g: 4 g: 0.1 g, and the initiator is azobisisobutyronitrile.

8. A method for preparing 2-amino-4-nitrophenol according to claim 6, characterized in that: Modified montmorillonite is processed by the following steps: B1, adding montmorillonite and sodium hydroxide into a ball mill, and ball milling for 40-50 minutes to obtain a montmorillonite mixed powder; B2, adding the montmorillonite mixed powder into a nitrogen-protected tubular furnace, heating the tubular furnace to 320-360° C. at a heating rate of 5-8° C. / min, and heat preservation for 40-60 min, and post-treating to obtain pretreated montmorillonite; B3, adding the pretreated montmorillonite and deionized water into a reactor, ultrasonically dispersing for 30-50 min at room temperature, adding the polyacrylamide solution into the reactor, keeping the temperature and ultrasonically dispersing for 10-12 h, and post-treating to obtain the loaded montmorillonite; B4. Add the loaded montmorillonite, anhydrous ethanol and vinyl triethoxysilane into a reactor and stir. Increase the temperature of the reactor to 50-60° C., add a catalyst into the reactor, keep the temperature for 4-6 hours, and perform post-treatment to obtain modified montmorillonite.

9. A method for preparing 2-amino-4-nitrophenol according to claim 8, characterized in that: In step B1, the weight ratio of the montmorillonite to sodium hydroxide is 10:3-4; in step B3, the amount ratio of the pretreated montmorillonite, deionized water and polyacrylamide solution is 5g:50mL:5g, and the polyacrylamide solution is composed of polyacrylamide and deionized water in a weight ratio of 1:10; in step B4, the amount ratio of the loaded montmorillonite, anhydrous ethanol, vinyltriethoxysilane and catalyst is 5g:50mL:2g:10mL, and the catalyst is 0.1-0.2mol / L sodium hydroxide solution.

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