CN115536515A - Preparation method of 2-hydroxy-6-naphthoic acid - Google Patents

Abstract

The invention provides a preparation method of 2-hydroxy-6-naphthoic acid, the preparation method comprising steps: S1, salt-forming reaction; S2, dehydration and drying; S3, carboxylation and dissolution; S4, neutralization and filtration; S5 , decolorization; S6, acid analysis; S7, refined drying, the preparation method of 2-hydroxy-6-naphthoic acid of the present invention can obtain the 2-hydroxy-6-naphthoic acid of purity up to 92%～95%, and preparation The amount of waste water produced in the 2-hydroxy-6-naphthoic acid process is small, and a waste water treatment system capable of comprehensively treating the waste water produced in the preparation process of 2-hydroxy-6-naphthoic acid is provided.

Description

A kind of preparation method of 2-hydroxy-6-naphthoic acid

technical field

The invention relates to a production method of an organic chemical intermediate, in particular to a preparation method of 2-hydroxy-6-naphthoic acid.

Background technique

2-Hydroxy-6-naphthoic acid, also known as 2,6 acid, English name is 2-Hydroxy-6-naphthoic acid, chemical formula is C ₁₁ H ₈ O ₃ , has good heat resistance and processing performance, is an engineering plastic , Organic pigments, liquid crystal materials, important organic intermediates in the field of medicine. With the rapid development of technologies such as liquid crystals, higher and higher requirements are placed on the purity of 2,6 acid, which is one of the raw materials for preparing liquid crystal materials.

Usually, 2,6 acid is obtained by using 2-naphthol through the Kolbe-Schmidt reaction, but the preparation process of this 2,6 acid contains main reactions and multiple side reactions, and impurities are easily introduced, which not only makes the preparation The quality of the obtained 2,6-acid product is not high, and the 2,6-acid product needs to be decolorized, impurity-removed, purified and refined for many times, which in turn leads to a large amount of production wastewater in the production process of 2,6-acid , These wastewaters are highly acidic and contain various chemical substances, and must be treated to meet the discharge standards. However, there is currently no effective method for treating the wastewater produced in the process of preparing 2-hydroxy-6-naphthoic acid.

Contents of the invention

The present invention designs a kind of preparation method of 2-hydroxyl-6-naphthoic acid, to solve the low purity of 2-hydroxyl-6-naphthoic acid product obtained by Kolbe-Schmidt reaction at present, the waste water that the preparation process produces is much , and the lack of effective means of treating wastewater technical problems.

In order to solve the above problems, the invention discloses a kind of preparation method of 2-hydroxyl-6-naphthoic acid, comprising steps:

S1, salt formation reaction:

(1) Add 500-1000 parts by weight of 2-naphthol, 150-200 parts by weight of 2-hydroxy-3-naphthoic acid, 100-300 parts by weight of potassium carbonate and an appropriate amount of solvent oil into the salt-forming kettle, and then open the To the vent valve of the salt kettle, add 700 to 1000 parts by weight of an aqueous potassium hydroxide solution with a concentration of 40 to 60%;

(2) After adding the materials, close the vent valve of the salt-forming kettle, start stirring and raise the temperature to 130-140°C, and then carry out the salt-forming reaction at 130-140°C with stirring for 1.5-2.5 hours;

S2, dehydration and drying:

(1) After the salt-forming reaction is completed, open the dehydration valve of the carboxylation kettle, press the material after the salt-forming reaction into the carboxylation kettle from the salt-forming kettle, then start the carboxylation kettle to stir, and the stirring speed is 100～120 rpm, And open the heat transfer oil valve of the jacket of the carboxylation kettle to heat up, and carry out normal pressure dehydration by raising the temperature;

(2) When the temperature in the carboxylation tank reaches 180-200°C, turn on the vacuum, and continue to remove moisture through the condenser or steaming phenol receiving tank;

S3, carboxylation and dissolution:

(1) After the dehydration and drying of the material in the carboxylation kettle is completed, close the carboxylation kettle dehydration valve and close the vacuum;

(2) Adjust the rotation speed of the carboxylation kettle to 100-150 rpm, feed CO2 through the CO2 vent valve to carry out the carboxylation reaction, the carboxylation process temperature is controlled between 220-230 °C, and the carboxylation reaction time is 4 ~5h;

(3) After the carboxylation reaction is finished, close the stirring device of the carboxylation kettle, let off the pressure in the carboxylation kettle, and reduce the pressure in the carboxylation kettle to normal pressure;

(4) pumping 1300-1800 parts by weight of water into the carboxylation kettle by the hot water tank to dissolve the material, and then pressing the material into the neutralization kettle;

S4, neutralization and filtration:

(1) After the material is pressed into the neutralization tank from the carboxylation tank, keep the temperature of the material between 50 and 60°C under stirring, and slowly add sulfuric acid with a concentration of 25 to 35% to neutralize the material in the neutralization tank. The pH was adjusted to 6.6-6.7, and then cooled to 15-20°C for 1 hour;

(2) Open the valve of the filter press, pump the material into the filter press to filter, and the filter cake obtained by filtering is washed with water until the lotion is basically colorless,

(3) The filtrate obtained by filtering is transferred to a layered kettle, and after standing for 0.5 to 1 hour, the layers are separated, and the water phase is poured into the decolorization kettle;

S5, decolorization:

(1) Start the decolorization kettle to stir, open the heating steam valve of the decolorization kettle to heat, add 20-40kg of activated carbon below 60°C, continue to heat up to 90-100°C and keep it warm for 0.5-1.0h for decolorization;

(2) Open the filter press valve to filter the decolorized material, and the filtrate obtained by filtering is pumped into the acid analysis kettle, and the filter residue is collected;

S6, acid analysis:

(1) Start the acid analysis tank to stir, open the heating steam valve of the acid analysis tank, heat up, and add an appropriate amount of sulfuric acid with a concentration of 25-35% at the same time to adjust the pH of the material in the acid analysis tank to 6-7, and then heat up to 70-80 °C, slowly add sulfuric acid with a concentration of 25-35% for acidification reaction, and the pH value at the end of the acidification reaction is 2.0-2.5;

(2) After the acidification is completed, close the sulfuric acid valve and the heating steam valve, open the cooling water valve, and cool the material to room temperature under stirring. After standing for 1-2 hours, open the discharge valve to filter, and the filter cake is the crude product of 2,6 acid ;

S7, refining and drying:

(1) adding water and activated carbon to the prepared 2,6 acid crude product for refining;

(2) The refined 2,6 acid is washed with water, and the centrifuged product is sent to an airflow dryer for drying, and the 2,6 acid product is obtained after drying.

Further, in the step S1, the solvent oil is straight-run light diesel oil.

Further, in the step S4, the filter cake obtained by filtering is washed with water until the washing liquid is basically colorless, then the filter cake is shoveled off, and the filter cake is sent to a distillation pot to recover 2-naphthol by distillation.

Further, in the step S4, the filtered filtrate is transferred to a layered kettle, and after standing for 0.5-1 hour, the layers are separated, the water phase is put into the decolorization kettle, and the oil phase is pumped into the oil head tank for the next salt formation .

Further, in the step S6, after the acidification is completed, the filtered filtrate is sent to the acid analysis tank, and sulfuric acid with a concentration of 25-35% is added to adjust the pH value, so that 2-hydroxy-3-naphthoic acid is precipitated and centrifuged 2-Hydroxy-3-naphthoic acid is obtained.

Further, in the step S1, the 2-hydroxy-3-naphthoic acid is the 2-hydroxy-3-naphthoic acid obtained by centrifugal separation in the step S6.

A kind of waste water treatment system that the preparation process of 2-hydroxyl-6-naphthoic acid produces, and described waste water treatment system is used to process the waste water that the preparation method of above-mentioned 2-hydroxyl-6-naphthoic acid produces, and described waste water treatment system comprises sequentially setting of:

Mother liquor water primary adsorption unit,

Mother liquor water secondary adsorption unit,

Mother liquor water three-stage adsorption unit,

and the biochemical processing unit,

Wherein, the primary adsorption unit of the mother liquid water includes a primary adsorption tower, a three-effect evaporator, and a primary neutralization tank;

The secondary adsorption unit for mother liquor water includes: a secondary adsorption tower, a secondary neutralization tank, and a secondary phenol-water separator;

The mother liquor water tertiary adsorption unit includes: a tertiary adsorption tower, a tertiary neutralization tank and a tertiary phenol-water separator.

Further, in the primary adsorption unit of the mother liquid water, the primary adsorption tower is respectively connected with the three-effect evaporator and the primary neutralization tank, and the 2-hydroxyl-6-naphthoic acid produced during the production process The mother liquid water first passes into the first-stage adsorption tower for alkali analysis treatment, the water phase produced after the alkali analysis treatment enters the three-effect evaporator for further treatment, and the analysis solution produced after the alkali analysis treatment enters the Acid neutralization treatment is carried out in the primary neutralization tank.

Further, in the secondary adsorption unit of mother liquid water, the secondary adsorption tower, the secondary neutralization tank and the secondary phenolic water separator are connected in sequence, and the high phenolic water discharged from the primary neutralization tank is first Enter the secondary adsorption tower for alkali analysis treatment, after the alkali analysis, the analysis solution discharged from the secondary adsorption tower enters the secondary neutralization tank for acid neutralization treatment, and the secondary adsorption tower discharges The low-phenol water enters the mother liquor water tertiary adsorption unit for further processing.

Further, in the three-stage adsorption unit of mother liquid water, the three-stage adsorption tower, the three-stage neutralization tank and the three-stage phenol water separator are connected in sequence, and the low-phenol water discharged from the two-stage adsorption tower first enters the Alkali analysis is carried out in the three-stage adsorption tower, and after the alkali analysis, the analysis solution discharged from the three-stage adsorption tower enters the three-stage neutralization tank for acid neutralization treatment. The water phase continues to enter the biochemical treatment unit for treatment.

The preparation method of 2-hydroxyl-6-naphthoic acid described in the application can obtain 2-hydroxyl-6-naphthoic acid with a purity as high as 92% to 95%, and the waste water produced in the process of preparing 2-hydroxyl-6-naphthoic acid The amount is small, and a waste water treatment system capable of comprehensively treating the waste water produced in the preparation process of 2-hydroxy-6-naphthoic acid is provided.

Description of drawings

Fig. 1 is the preparation method flowchart of 2-hydroxyl-6-naphthoic acid of the present invention;

Fig. 2 is the structural representation of mother liquor water primary adsorption unit of the present invention;

Fig. 3 is the structural representation of the mother liquid water secondary adsorption unit of the present invention;

Fig. 4 is the structural representation of mother liquid water tertiary adsorption unit of the present invention;

Fig. 5 is a schematic structural diagram of the biochemical treatment unit of the present invention.

Explanation of reference signs:

101, first-level adsorption tower; 102, three-effect evaporator; 103, first-level neutralization tank; 103a, first-level neutralization tank; 103b, second-level neutralization tank; 201, second-level adsorption tower; 202 203, secondary phenol-water separator; 301, tertiary adsorption tower; 302, tertiary neutralization tank; 303, tertiary phenol-water separator; 401, mixing tank; 402, regulating tank; 403. Biological selection tank; 404. Aerobic tank; 405. Primary sedimentation tank; 406. Secondary sedimentation tank; 407. Concentration tank; 408. Mud storage tank; 409. Press filter device.

detailed description

In order to make the above objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, a kind of preparation method of 2-hydroxyl-6-naphthoic acid comprises steps:

S1, salt formation reaction:

(1) Add 500-1000 parts by weight of 2-naphthol, 150-200 parts by weight of 2-hydroxy-3-naphthoic acid, 100-300 parts by weight of potassium carbonate and an appropriate amount of solvent oil into the salt-forming kettle, and then open the To the vent valve of the salt kettle, add 700 to 1000 parts by weight of an aqueous potassium hydroxide solution with a concentration of 40 to 60%;

(2) After adding the materials, close the vent valve of the salt-forming kettle, start stirring and raise the temperature to 130-140°C, and then carry out the salt-forming reaction at 130-140°C with stirring for 1.5-2.5 hours;

S2, dehydration and drying:

(1) After the salt-forming reaction is completed, open the dehydration valve of the carboxylation kettle, press the material after the salt-forming reaction into the carboxylation kettle from the salt-forming kettle, then start the carboxylation kettle to stir, and the stirring speed is 100～120 rpm, And open the heat transfer oil valve of the jacket of the carboxylation kettle to heat up, and carry out normal pressure dehydration by raising the temperature;

(2) When the temperature in the carboxylation tank reaches 180-200°C, turn on the vacuum, and continue to remove moisture through the condenser or steaming phenol receiving tank;

S3, carboxylation and dissolution:

(1) After the dehydration and drying of the material in the carboxylation kettle is completed, close the carboxylation kettle dehydration valve and close the vacuum;

(2) Adjust the rotation speed of the carboxylation kettle to 100-150 rpm, and pass _CO2 through the _CO2 vent valve to carry out the carboxylation reaction. 4 to 5 hours;

(3) After the carboxylation reaction is finished, close the stirring device of the carboxylation kettle, let off the pressure in the carboxylation kettle, and reduce the pressure in the carboxylation kettle to normal pressure;

(4) pumping 1300-1800 parts by weight of water into the carboxylation kettle by the hot water tank to dissolve the material, and then pressing the material into the neutralization kettle;

S4, neutralization and filtration:

(1) After the material is pressed into the neutralization tank from the carboxylation tank, keep the temperature of the material between 50 and 60°C under stirring, and slowly add sulfuric acid with a concentration of 25 to 35% to neutralize the material in the neutralization tank. The pH was adjusted to 6.6-6.7, and then cooled to 15-20°C for 1 hour;

(2) Open the valve of the filter press, pump the material into the filter press for filtration, and wash the filtered cake with water until the lotion is basically colorless, shovel the filter cake, and send the filter cake to the distillation kettle for distillation and recovery 2-naphthol;

(3) The filtrate obtained by filtering is transferred to a layered kettle, and after standing for 0.5 to 1 hour, the layers are separated, the water phase is poured into the decolorization kettle, and the oil phase is pumped into the oil head tank for the next salt formation;

S5, decolorization:

(1) Start the decolorization kettle to stir, open the heating steam valve of the decolorization kettle to heat, add 20-40kg of activated carbon below 60°C, continue to heat up to 90-100°C and keep it warm for 0.5-1.0h for decolorization;

(2) Open the filter press valve to filter the decolorized material, and the filtrate obtained by filtering is pumped into the acid analysis kettle, and the filter residue is collected;

S6, acid analysis:

(1) Start the acid analysis tank to stir, open the heating steam valve of the acid analysis tank, heat up, and add an appropriate amount of sulfuric acid with a concentration of 25-35% at the same time to adjust the pH of the material in the acid analysis tank to 6-7, and then heat up to 70-80 °C, slowly add sulfuric acid with a concentration of 25-35% for acidification reaction, and the pH value at the end of the acidification reaction is 2.0-2.5;

(2) After the acidification is completed, close the sulfuric acid valve and the heating steam valve, open the cooling water valve, and cool the material to room temperature under stirring. After standing for 1-2 hours, open the discharge valve to filter, and the filter cake is the crude product of 2,6 acid ;

(3) The filtrate is sent to the acid analysis tank, and the sulfuric acid with a concentration of 25 to 35% is added to adjust the pH value, so that 2-hydroxy-3-naphthoic acid (abbreviated as 2,3 acid is the isomer of product 2,6 acid) Body) is separated out, and the 2-hydroxyl-3-naphthoic acid that centrifugation obtains returns to the salt-forming kettle for the next batch of production;

S7, refining and drying:

(1) adding water and activated carbon to the prepared 2,6 acid crude product for refining;

(2) The refined 2,6 acid is washed with water, and the centrifuged product is sent to an airflow dryer for drying to obtain 2,6 acid with a 2,6 acid content of 92% to 95%.

Preferably, in the step S1, the solvent oil is straight-run gas oil, and the solvent oil is mainly used as a dispersant to promote heat conduction and uniform reaction.

Preferably, in the step S1, the 2-hydroxyl-3-naphthoic acid is the 2-hydroxyl-3-naphthoic acid recovered in the step S6, and the addition of the 2-hydroxyl-3-naphthoic acid is mainly It is to suppress the generation of potassium 2,3 acid in the carboxylation reaction and improve the reaction yield of potassium 2,6 acid.

Preferably, in the step S7, the purpose of using water and activated carbon for refined decolorization is to use activated carbon to decolorize the product discoloration caused by the oxidation of 2,6 acid, and remove trace amounts of 2,3 acid in the crude product of 2,6 acid .

In the above-mentioned method for preparing 2-hydroxyl-6-naphthoic acid, by adding 2-hydroxyl-3-naphthoic acid in the salt-forming kettle, the generation of side reactions is suppressed, which is conducive to improving the production of 2-hydroxyl-6-naphthoic acid. The purity of the 2,6-acid crude product was optimized to reduce the generation of production wastewater, reduce the pressure for subsequent wastewater treatment, and obtain 2-hydroxy-6-naphthoic acid products with higher purity.

In addition, as shown in Figures 2 to 5, the application also provides a wastewater treatment system produced during the preparation of 2-hydroxy-6-naphthoic acid, which includes sequentially arranged:

Mother liquor water primary adsorption unit,

Mother liquor water secondary adsorption unit,

Mother liquor water three-stage adsorption unit,

and the biochemical processing unit,

Wherein, the primary adsorption unit of mother liquid water includes a primary adsorption tower 101, a three-effect evaporator 102, and a primary neutralization tank 103;

The mother liquid water secondary adsorption unit includes: secondary adsorption tower 201, secondary neutralization tank 202 and secondary phenol water separator 203;

The tertiary adsorption unit for mother liquid water includes: a tertiary adsorption tower 301 , a tertiary neutralization tank 302 and a tertiary phenol-water separator 303 .

Further, in the primary adsorption unit of the mother liquor water, the primary adsorption tower 101 is connected with the three-effect evaporator 102 and the primary neutralization tank 103 respectively, and the 2-hydroxyl-6-naphthoic acid production The mother liquid water produced in the process is first passed into the first-stage adsorption tower 101 for alkali analysis treatment, and the water phase produced after the alkali analysis treatment enters the three-effect evaporator 102 for further treatment, and the water phase produced after the alkali analysis treatment The analysis solution enters the primary neutralization tank 103 for acid neutralization treatment.

Furthermore, in the primary adsorption unit for mother liquid water, the primary neutralization tank 103 includes a first primary neutralization tank 103a and a second primary neutralization tank 103b, and the primary adsorption tower 101 can be The mother liquor water in it is subjected to alkali analysis treatment for many times.

Preferably, the primary adsorption tower 101 can carry out two alkali desorption treatments on the mother liquid water in it, wherein, the primary desorption solution produced by the first alkali desorption treatment directly enters the first-level neutralization tank 103a Acid neutralization treatment is carried out, and the secondary analysis solution produced by the first alkali analysis treatment is directly entered into the second-level neutralization tank 103b for acid neutralization treatment.

Further, the water phase produced after alkali analysis treatment enters the three-effect evaporator 102 for evaporation treatment, and the generated water vapor enters the biochemical treatment unit after condensation treatment to continue processing. At the same time, through the three-effect evaporation Potassium sulfate can be recovered by evaporating treatment in vessel 102.

Further, the high-phenolic water produced after the primary analysis liquid is processed by the first-level neutralization tank 103a enters the mother liquor water secondary adsorption unit to continue processing, and at the same time, the first-level neutralization tank 103a can Recover the acid; the high-phenolic water produced after the secondary analysis solution is processed by the second-level neutralization tank 103b enters the mother liquor water secondary adsorption unit to continue processing, and at the same time, passes through the second-level neutralization tank 103b was able to recover phenol.

Further, in the secondary adsorption unit of mother liquid water, the secondary adsorption tower 201, the secondary neutralization tank 202 and the secondary phenol water separator 203 are connected in sequence, and the discharged from the primary neutralization tank 103 The high-phenol water first enters the secondary adsorption tower 201 for alkali analysis treatment, and after the alkali analysis treatment, the analysis solution discharged from the secondary adsorption tower 201 enters the secondary neutralization tank 202 for acid neutralization treatment, The low-phenol water discharged from the secondary adsorption tower 201 enters the tertiary adsorption unit of mother liquid water for further treatment.

Furthermore, in the secondary adsorption unit of the mother liquid water, after the acid neutralization treatment is carried out by the secondary neutralization tank 202, the material discharged from the secondary neutralization tank 202 continues to enter the secondary phenolic water The treatment is carried out in the separator 203, and the phenol can be recovered after being treated by the secondary phenol water separator 203. At the same time, the high-phenol water discharged from the secondary phenol water separator 203 continues to enter the secondary adsorption tower 201 for treatment.

Further, in the three-stage adsorption unit of mother liquid water, the three-stage adsorption tower 301, the three-stage neutralization tank 302 and the three-stage phenol water separator 203 are connected in sequence, and the low Phenol water first enters the three-stage adsorption tower 301 for alkali analysis treatment, and after the alkali analysis place, the analysis solution discharged from the three-stage adsorption tower 301 enters the three-stage neutralization tank 302 for acid neutralization treatment. The water phase discharged from the three-stage adsorption tower 301 continues to enter the biochemical treatment unit for treatment.

Furthermore, in the tertiary adsorption unit of the mother liquid water, after the acid neutralization treatment in the tertiary neutralization tank 302, the material discharged from the tertiary neutralization tank 302 continues to enter the tertiary phenol water The treatment is carried out in the separator 203, and the phenol can be recovered through the treatment in the three-stage phenol-water separator 203. At the same time, the high-phenol water discharged from the three-stage phenol-water separator 203 continues to enter the secondary adsorption tower 201 for treatment.

Further, the biochemical treatment unit includes sequentially arranged:

Mixing tank 401, regulating tank 402, biological selection tank 403, aerobic tank 404 and sedimentation tank, the mother liquor water treated by the mother liquor water primary adsorption unit, mother liquor water secondary adsorption unit and mother liquor water tertiary adsorption unit, And other waste water that produces in the process of preparing 2-hydroxyl-6-naphthoic acid first enters in described mixing pool 401, after mixing uniformly in described mixing pool 401, enters in described regulating pool 402, in described regulating pool 402 After adjusting the pH etc., it enters the biological selection pool 403, and after being treated with nutrient solution in the biological selection pool 403, it is discharged into the aerobic pool 404, and decarburization and destocking are carried out in the aerobic pool 404. treatment, and then discharged into the sedimentation tank for precipitation to achieve solid-liquid separation.

Further, the sedimentation tank includes a primary sedimentation tank 405 and a secondary sedimentation tank 406, the water inlet of the primary sedimentation tank 405 is connected with the outlet of the aerobic tank 404, the primary sedimentation tank 405 The outlet is connected to the water inlet of the secondary sedimentation tank 406, and the outlet of the secondary sedimentation tank 406 is connected to the waste water discharge pipeline, so that the water discharged from the aerobic tank 404 will flow through the primary sedimentation tank in turn. The pool 405 and the secondary sedimentation tank 406 then enter the waste water discharge pipeline.

Further, the biochemical treatment unit also includes:

Concentration tank 407, sludge storage tank 408 and filter press device 409, wherein, the sludge discharged from the first-stage sedimentation tank 405 and the sludge discharged from the secondary sedimentation tank 406 directly enter the concentration tank 407 for concentration treatment The return sludge generated by the primary sedimentation tank 405 and the secondary sedimentation tank 406 enters the biological selection tank 403 again for treatment.

Further, the mud storage tank 408 is connected to the thickening tank 407, and the sludge treated by the thickening tank 407 enters the mud storage tank 408 for temporary storage, and the filter press device 409 is connected to the mud storage tank 408 connected, the filter press device 409 can perform press filter treatment on the water-containing sludge in the mud storage tank 408, and the sludge filter cake obtained after press filter can be processed by transporting to landfill.

It should be noted that, in the waste water treatment system produced in the 2-hydroxyl-6-naphthoic acid preparation process described in the application, each component in the waste water treatment system, such as one of the primary adsorption units of mother liquor water Stage adsorption tower 101, three-effect evaporator 102, primary neutralization tank 103, and secondary adsorption tower 201, secondary neutralization tank 202 and secondary phenol-water separator 203 in the mother liquor water secondary adsorption unit, and mother liquor The tertiary adsorption tower 301, the tertiary neutralization tank 302 and the tertiary phenolic water separator 303 in the water tertiary adsorption unit, as well as the mixing tank 401, regulating tank 402, biological selection tank 403, aerobic Pool 404, settling tank, thickening tank 407, mud storage tank 408 and filter press device 409 etc. are all prior art, its specific structure and working principle, and the technical effect that can realize all can refer to prior art, and this application describes The main improvement of the waste water treatment system and the creative work paid are mainly to combine the above-mentioned components organically to form a system that can effectively treat all kinds of waste water produced in the preparation process of 2-hydroxy-6-naphthoic acid and make it conform to Wastewater discharge regulations for wastewater treatment systems.

As some embodiments of the present application, the mother liquid water is the filtrate obtained after centrifugal separation of 2-hydroxy-3-naphthoic acid in the step S6.

As some embodiments of the present application, in the present application, other wastewater generated during the preparation of 2-hydroxy-6-naphthoic acid includes: washing water, condensed water, workshop wastewater, ground flushing wastewater, quality inspection wastewater, waste gas treatment device wastewater And the domestic sewage of factory personnel. Wherein, the washing water may be the washing water produced in the process of washing 2-hydroxy-6-naphthoic acid or the water phase produced after it is adsorbed.

The preparation method of above-mentioned 2-hydroxyl-6-naphthoic acid is illustrated by specific examples below:

Example 1

S1, salt formation reaction:

Open the 5000L salt-forming kettle, directly add 2-hydroxy-3-naphthoic acid reclaimed by 2-naphthol solid 800kg and 182kg through a scale, and directly put 2000L of straight-run light diesel oil into the salt-forming kettle after being measured by the solvent head tank. 200kg of solid potassium carbonate is directly added to the salt-forming kettle after being weighed by a scale, and then the feeding valve is closed. Afterwards, open the vent valve of the salt-forming kettle, and put into about 860kg of 50% potassium hydroxide by the liquid alkali head tank. After all the materials are added, close the vent valve of the salt-forming kettle, start the stirring device of the salt-forming kettle and raise the temperature to 135°C, and then stir and react at 135°C for 2 hours;

S2, dehydration and drying:

After the salt-forming reaction is completed, open the dehydration valve of the 5000L carboxylation kettle, and press the material qualified for salt formation into the carboxylation kettle with direct steam from the salt-forming kettle. Then start the carboxylation kettle to stir, the stirring speed is 110 rpm, and open the heat transfer oil valve of the jacket of the carboxylation kettle at the same time to dehydrate the material rapidly. Receiving tank to remove moisture;

S3, carboxylation and dissolution:

After the dehydration and drying of the material in the carboxylation kettle is completed, close the dehydration valve of the carboxylation kettle and turn off the vacuum. The rotation speed of the carboxylation kettle was adjusted to 132 rpm, and the carboxylation reaction was carried out by passing CO ₂ through the CO ₂ ventilation valve. The carboxylation reaction temperature was 223° C., and the time was 4.5 hours. After the carboxylation reaction is completed, close the stirring, release the pressure in the carboxylation kettle, and reduce the pressure in the carboxylation kettle to normal pressure; then pump 1500L of water into the carboxylation kettle from the hot water tank, open the valve at the bottom of the kettle after the water is finished, and then Open the valve of the carboxylation kettle to transfer the material to the neutralization kettle, and press the material into the neutralization kettle.

S4, neutralization and filtration:

After the material is pressed into the neutralization tank from the carboxylation tank, keep the temperature of the material at 52°C under stirring, slowly add sulfuric acid with a concentration of 30% to the neutralization tank to neutralize the material, adjust the pH of the material to 6.6-6.7, and then continue Cool down at 17°C for 1 hour. Then open the valve of the plate and frame filter press, pump the material into the filter press for filtration, wash the filter cake with slag water until the lotion is basically colorless, shovel the filter cake, and send the filter cake to the distillation kettle for distillation and recovery of 2- Naphthol. The filtrate is transferred from the submerged pump to the stratified tank through the ground tank, and after standing for 0.8 hours, the layers are separated. The water phase is sent to the water receiving tank and then pumped into the decolorizing tank. The oil phase is pumped into the oil high level tank through the oil receiving tank for the next time For salt.

S5, decolorization:

Start the decolorizing kettle to stir, open the heating steam valve to heat, add 30kg of activated carbon below 60°C, and continue to heat up to about 95°C for 0.7 hours. Open the valve of the filter press to filter, first turn on the circulation, wait for the filtrate to be clarified, then pump the filtrate into the acid analysis kettle by the pump, and collect the filter residue.

S6, acid analysis:

Start stirring, open the heating steam valve, raise the temperature, and at the same time add an appropriate amount of sulfuric acid with a concentration of 30% to adjust the pH of the material in the acid analysis tank to pH 6, then raise the temperature to 76°C, and slowly add sulfuric acid with a concentration of 30% to carry out the acidification reaction , the pH at the end of acidification was 2.0. After the acidification is completed, close the sulfuric acid valve and the heating steam valve, open the cooling water valve, and cool to room temperature under stirring. After standing for 1.5 hours, open the discharge valve to filter. The filter cake is the crude product of 2,6 acid, and the filter cake is sent to refine The process is refined. The filtrate is sent to the acid analysis tank, and then sulfuric acid with a concentration of 30% is added to adjust the pH value, and 2-hydroxy-3-naphthoic acid is precipitated, and the 2,3 acid obtained by centrifugation is returned to the salt-forming tank for the next batch of production.

S7, refining and drying:

Add 600L of water and 20kg of activated carbon to the crude 2,6 acid obtained in the previous process for refined decolorization, add 400L of water to wash after decolorization, and send the centrifuged product to an airflow dryer for drying. % of 2,6 acid products.

Example 2

S1, salt formation reaction:

Open the 5000L salt-forming kettle, directly add 2-hydroxy-3-naphthoic acid reclaimed by 2-naphthol solid 500kg and 155kg through the scale, and directly put 1500L of straight-run light diesel oil into the salt-forming kettle after being measured by the solvent head tank. 100kg of solid potassium carbonate is directly added to the salt forming kettle after being measured by a scale, and then the feeding valve is closed. Afterwards, open the vent valve of the salt-forming kettle, and put into about 720kg of 50% potassium hydroxide from the liquid alkali head tank. After all the materials are added, close the vent valve of the salt-forming kettle, start the stirring device of the salt-forming kettle and raise the temperature to 130°C, and stir for 2.5 hours at 130°C;

S2, dehydration and drying:

After the salt-forming reaction is completed, open the dehydration valve of the 5000L carboxylation kettle, and press the material qualified for salt formation into the carboxylation kettle with direct steam from the salt-forming kettle. Then start the carboxylation kettle to stir, the stirring speed is 100 rpm, and open the heat transfer oil valve of the jacket of the carboxylation kettle at the same time to dehydrate the material rapidly. Receiving tank to remove moisture;

S3, carboxylation and dissolution:

After the dehydration and drying of the material in the carboxylation kettle is completed, close the dehydration valve of the carboxylation kettle and turn off the vacuum. The rotation speed of the carboxylation kettle was adjusted to 105 rpm, and the carboxylation reaction was carried out by passing CO ₂ through the CO ₂ ventilation valve. The carboxylation reaction temperature was 220° C., and the time was 5 hours. After the carboxylation reaction is completed, close the stirring, release the pressure in the carboxylation kettle, and reduce the pressure in the carboxylation kettle to normal pressure; then pump 1300L of water into the carboxylation kettle from the hot water tank, open the valve at the bottom of the kettle after the water is finished, and then Open the valve of the carboxylation kettle to transfer the material to the neutralization kettle, and press the material into the neutralization kettle.

S4, neutralization and filtration:

After the material is pressed into the neutralization tank from the carboxylation tank, keep the temperature of the material at 50°C under stirring, slowly add sulfuric acid with a concentration of 30% to the neutralization tank to neutralize the material, adjust the pH of the material to 6.6-6.7, and then continue Cool down at 15°C for 1 hour. Then open the valve of the plate and frame filter press, pump the material into the filter press for filtration, wash the filter cake with slag water until the lotion is basically colorless, shovel the filter cake, and send the filter cake to the distillation kettle for distillation and recovery of 2- Naphthol. The filtrate is transferred from the submerged pump to the stratified tank through the ground tank, and after standing for 0.5 hours, the layers are separated. The water phase is sent to the water receiving tank and then pumped into the decolorizing tank. The oil phase is pumped into the oil high level tank through the oil receiving tank for the next time For salt.

S5, decolorization:

Start the decolorization kettle to stir, open the heating steam valve to heat, add 20kg of activated carbon at 55°C, and continue to heat up to about 90°C for 0.5 hours. Open the valve of the filter press to filter, first turn on the circulation, wait for the filtrate to be clarified, then pump the filtrate into the acid analysis kettle by the pump, and collect the filter residue.

S6, acid analysis:

Start stirring, open the heating steam valve, raise the temperature, and at the same time add an appropriate amount of sulfuric acid with a concentration of 30% to adjust the pH of the material in the acid analysis tank to pH 6, then raise the temperature to 70°C, and slowly add sulfuric acid with a concentration of 30% to carry out the acidification reaction , the pH at the end of acidification was 2.0. After the acidification is completed, close the sulfuric acid valve and the heating steam valve, open the cooling water valve, and cool to room temperature under stirring. After standing for 1 hour, open the discharge valve to filter. The filter cake is the crude product of 2,6 acid, and the filter cake is sent to refining The process is refined. The filtrate is sent to the acid analysis tank, and then sulfuric acid with a concentration of 30% is added to adjust the pH value, and 2-hydroxy-3-naphthoic acid is precipitated, and the 2,3 acid obtained by centrifugation is returned to the salt-forming tank for the next batch of production.

S7, refining and drying:

Add 600L of water and 20kg of activated carbon to the crude 2,6 acid obtained in the previous process for refined decolorization, add 400L of water to wash after decolorization, and send the centrifuged product to an airflow dryer for drying. % of 2,6 acid products.

Example 3

S1, salt formation reaction:

Open the 5000L salt-forming kettle, directly add 2-hydroxy-3-naphthoic acid recovered by 2-naphthol solid 1000kg and 200kg through the scale, and directly put 2500L of straight-run light diesel oil into the salt-forming kettle after being measured by the solvent head tank. 300kg of solid potassium carbonate is directly added to the salt forming kettle after being measured by a scale, and then the feeding valve is closed. Afterwards, open the vent valve of the salt-forming kettle, and put into about 1000kg of 50% potassium hydroxide from the liquid alkali head tank. After all the materials are added, close the vent valve of the salt-forming kettle, start the stirring device of the salt-forming kettle and raise the temperature to 140°C, and stir and react at 140°C for 1.5h;

S2, dehydration and drying:

After the salt-forming reaction is completed, open the dehydration valve of the 5000L carboxylation kettle, and press the material qualified for salt formation into the carboxylation kettle with direct steam from the salt-forming kettle. Then start the carboxylation kettle to stir, the stirring speed is 120 rpm, and open the heat transfer oil valve of the jacket of the carboxylation kettle at the same time to dehydrate the material rapidly. Receiving tank to remove moisture;

S3, carboxylation and dissolution:

After the dehydration and drying of the material in the carboxylation kettle is completed, close the dehydration valve of the carboxylation kettle and turn off the vacuum. The rotation speed of the carboxylation kettle was adjusted to 150 rpm, and the carboxylation reaction was carried out by passing CO ₂ through the CO ₂ ventilation valve. The carboxylation reaction temperature was 230° C., and the time was 4 hours. After the carboxylation reaction is completed, close the stirring, release the pressure in the carboxylation kettle, and reduce the pressure in the carboxylation kettle to normal pressure; then pump 1800L of water into the carboxylation kettle from the hot water tank, open the valve at the bottom of the kettle after the water is finished, and then Open the valve of the carboxylation kettle to transfer the material to the neutralization kettle, and press the material into the neutralization kettle.

S4, neutralization and filtration:

After the material is pressed into the neutralization tank from the carboxylation tank, keep the temperature of the material at 60°C under stirring, slowly add sulfuric acid with a concentration of 30% to the neutralization tank to neutralize the material, adjust the pH of the material to 6.6-6.7, and then continue Cool down at 20°C for 1 hour. Then open the valve of the plate and frame filter press, pump the material into the filter press for filtration, wash the filter cake with slag water until the lotion is basically colorless, shovel the filter cake, and send the filter cake to the distillation kettle for distillation and recovery of 2- Naphthol. The filtrate is transferred from the submerged pump to the stratified tank through the ground tank, and after standing for 1 hour, the layers are separated. The water phase is sent to the water receiving tank and then pumped into the decolorizing tank. The oil phase is pumped into the oil high level tank through the oil receiving tank for the next time For salt.

S5, decolorization:

Start the decolorization kettle to stir, open the heating steam valve to heat, add 30kg of activated carbon at 57°C, and continue to heat up to about 100°C for 1 hour. Open the valve of the filter press to filter, first turn on the circulation, wait for the filtrate to be clarified, then pump the filtrate into the acid analysis kettle by the pump, and collect the filter residue.

S6, acid analysis:

Start stirring, open the heating steam valve, raise the temperature, and at the same time add an appropriate amount of sulfuric acid with a concentration of 30% to adjust the pH of the material in the acid analysis tank to pH 7, then raise the temperature to 80°C, and slowly add sulfuric acid with a concentration of 30% to carry out the acidification reaction , the pH at the end of acidification was 2.5. After the acidification is completed, close the sulfuric acid valve and the heating steam valve, open the cooling water valve, and cool to room temperature under stirring. After standing for 2 hours, open the discharge valve to filter. The filter cake is the crude product of 2,6 acid, and the filter cake is sent to refining The process is refined. The filtrate is sent to the acid analysis tank, and then sulfuric acid with a concentration of 30% is added to adjust the pH value, and 2-hydroxy-3-naphthoic acid is precipitated, and the 2,3 acid obtained by centrifugation is returned to the salt-forming tank for the next batch of production.

S7, refining and drying:

Add 800L of water and 30kg of activated carbon to the crude 2,6 acid obtained in the previous process for refined decolorization. After decolorization, add 600L of water to wash, and the centrifuged product is sent to an airflow dryer for drying. After drying, the content of 2,6 acid is 95.1 % of 2,6 acid products.

Although the present invention is disclosed above, the present invention is not limited thereto. In the description of this specification, references to the terms "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific examples," or "some examples" are intended to mean that the implementation A specific feature, structure, material, or characteristic described by an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Claims (10)

1. A method for preparing 2-hydroxy-6-naphthoic acid is characterized by comprising the following steps:

s1, salt forming reaction:

(1) Adding 500-1000 parts by weight of 2-naphthol, 150-200 parts by weight of 2-hydroxy-3-naphthoic acid, 100-300 parts by weight of potassium carbonate and a proper amount of solvent oil into a salt forming kettle, then opening an emptying valve of the salt forming kettle, and adding 700-1000 parts by weight of 40-60% potassium hydroxide aqueous solution;

(2) After the materials are added, closing an emptying valve of the salt forming kettle, starting stirring, heating to 130-140 ℃, and then carrying out salt forming reaction for 1.5-2.5 h at 130-140 ℃ under stirring;

s2, dehydrating and drying:

(1) After the salifying reaction is finished, opening a dehydration valve of the carboxylation kettle, pressing materials subjected to the salifying reaction into the carboxylation kettle from the salifying kettle, starting the carboxylation kettle to stir at the stirring speed of 100-120 rpm, opening a jacket heat conduction oil valve of the carboxylation kettle to heat, and heating to perform normal-pressure dehydration;

(2) When the temperature in the carboxylation kettle reaches 180-200 ℃, opening vacuum, and continuously removing water through a condenser or a phenol steaming receiving groove;

s3, carboxylation and dissolution:

(1) After the materials in the carboxylation kettle are dehydrated and dried, closing a dehydration valve of the carboxylation kettle, and closing vacuum;

(2) The rotating speed of the carboxylation kettle is adjusted to 100-150 r/m, and CO is added ₂ The vent valve is filled with CO ₂ Carrying out carboxylation reaction, wherein the temperature in the carboxylation process is controlled to be between 220 and 230 ℃, and the carboxylation reaction time is 4 to 5 hours;

(3) After the carboxylation reaction is finished, closing a stirring device of the carboxylation kettle, releasing the pressure in the carboxylation kettle, and reducing the pressure in the carboxylation kettle to normal pressure;

(4) 1300-1800 parts by weight of water is pumped into the carboxylation kettle from a hot water tank to dissolve the materials, and then the materials are pressed into a neutralization kettle;

s4, neutralization and filtration:

(1) After the materials are pressed into a neutralization kettle from a carboxylation kettle, keeping the temperature of the materials between 50 and 60 ℃ under stirring, slowly adding 25 to 35 percent sulfuric acid into the neutralization kettle to neutralize the materials, adjusting the pH of the materials to 6.6 to 6.7, then cooling to 15 to 20 ℃ and placing for 1 hour;

(2) Opening a valve of the filter press, pumping the materials into the filter press by a pump for filtering, washing the filter cake obtained by filtering with water until the washing liquid is basically colorless,

(3) Transferring the filtrate obtained by filtering into a layering kettle, standing for 0.5-1 h, layering, and pumping the water phase into a decoloring kettle;

s5, decoloring:

(1) Starting a decoloring kettle for stirring, opening the decoloring kettle to heat a steam valve for heating, adding 20-40 kg of active carbon at the temperature of below 60 ℃, continuously heating to 90-100 ℃, and preserving heat for 0.5-1.0 h for decoloring;

(2) Opening a valve of the filter press to filter the decolored material, pumping the filtered liquid into an acid precipitation kettle, and collecting filter residues;

s6, acid separation:

(1) Starting an acid precipitation kettle for stirring, opening a heating steam valve of the acid precipitation kettle, heating, adding a proper amount of 25-35% sulfuric acid to adjust the pH value of the materials in the acid precipitation kettle to 6-7, heating to 70-80 ℃, slowly adding 25-35% sulfuric acid for an acidification reaction, wherein the pH value at the end point of the acidification reaction is 2.0-2.5;

(2) After acidification is finished, closing a sulfuric acid valve and a heating steam valve, opening a cooling water valve, cooling the material to room temperature under stirring, standing for 1-2 h, opening a discharge valve, and filtering to obtain a filter cake, namely a 2,6 acid crude product;

s7, refining and drying:

(1) Adding water and active carbon into the prepared crude 2,6 acid for refining;

(2) Washing the refined 2,6 acid with water, drying the centrifuged product in a pneumatic drier, and drying to obtain the 2,6 acid product.

2. The method of producing 2-hydroxy-6-naphthoic acid according to claim 1, wherein in the step S1, the solvent oil is straight-run light diesel oil.

3. The method of producing 2-hydroxy-6-naphthoic acid according to claim 1, wherein in the step S4, the filtered cake is washed with water until the washing solution is substantially colorless, the cake is scooped up, the cake is sent to a distillation still, and 2-naphthol is recovered by distillation.

4. The method for preparing 2-hydroxy-6-naphthoic acid as claimed in claim 1, wherein in step S4, the filtrate obtained by filtration is transferred to a layering kettle, is allowed to stand for 0.5 to 1 hour and then is layered, the water phase is pumped into a decoloring kettle, and the oil phase is pumped into an oil head tank for next salt formation.

5. The method according to claim 1, wherein in step S6, after the acidification is completed, the filtrate obtained by filtration is sent to an acid precipitation tank, sulfuric acid with a concentration of 25 to 35% is added to adjust the pH value, so that 2-hydroxy-3-naphthoic acid is precipitated, and 2-hydroxy-3-naphthoic acid is obtained by centrifugal separation.

6. The method of producing 2-hydroxy-6-naphthoic acid according to claim 5, wherein in step S1, the 2-hydroxy-3-naphthoic acid is 2-hydroxy-3-naphthoic acid obtained by centrifugal separation in step S6.

7. A wastewater treatment system generated in a 2-hydroxy-6-naphthoic acid production process, wherein the wastewater treatment system is used for treating wastewater generated in the 2-hydroxy-6-naphthoic acid production method according to any one of claims 1 to 6, and the wastewater treatment system comprises:

a primary adsorption unit of mother liquor water,

a secondary adsorption unit of the mother liquor water,

a three-stage adsorption unit for mother liquor water,

and a biochemical treatment unit, wherein the biochemical treatment unit is provided with a plurality of biochemical treatment units,

the mother liquid water primary adsorption unit comprises a primary adsorption tower (101), a triple-effect evaporator (102) and a primary neutralization tank (103);

the mother liquor water secondary adsorption unit comprises: a secondary adsorption tower (201), a secondary neutralization tank (202) and a secondary phenol water separator (203);

the tertiary adsorption unit of mother liquor water includes: a three-stage adsorption tower (301), a three-stage neutralization tank (302) and a three-stage phenol water separator (303).

8. The wastewater treatment system according to claim 7, wherein in the primary mother liquor absorption unit, the primary absorption tower (101) is respectively connected with the triple-effect evaporator (102) and the primary neutralization tank (103), mother liquor water generated in the production process of the 2-hydroxy-6-naphthoic acid is firstly introduced into the primary absorption tower (101) for alkali desorption treatment, a water phase generated after the alkali desorption treatment enters the triple-effect evaporator (102) for continuous treatment, and a desorption solution generated after the alkali desorption treatment enters the primary neutralization tank (103) for acid neutralization treatment.

9. The wastewater treatment system according to claim 8, wherein in the mother liquor secondary adsorption unit, the secondary adsorption tower (201), the secondary neutralization tank (202) and the secondary phenol water separator (203) are connected in sequence, the high phenol water discharged from the primary neutralization tank (103) firstly enters the secondary adsorption tower (201) for alkali desorption treatment, the desorption solution discharged from the secondary adsorption tower (201) after alkali desorption enters the secondary neutralization tank (202) for acid neutralization treatment, and the low phenol water discharged from the secondary adsorption tower (201) enters the mother liquor tertiary adsorption unit for continuous treatment.

10. The wastewater treatment system according to claim 9, wherein in the mother liquor water tertiary adsorption unit, the tertiary adsorption tower (301), the tertiary neutralization tank (302) and the tertiary phenol water separator (203) are connected in sequence, the low phenol water discharged from the secondary adsorption tower (201) firstly enters the tertiary adsorption tower (301) for alkali desorption treatment, the desorption solution discharged from the tertiary adsorption tower (301) after alkali desorption enters the tertiary neutralization tank (302) for acid neutralization treatment, and the water discharged from the tertiary adsorption tower (301) sequentially enters the biochemical treatment unit for treatment.

Images