2-hydroxy-benzonitrile kettle residue recovery treatment process

Abstract

The invention discloses a 2-hydroxy-benzonitrile kettle residue recovery treatment process, and belongs to the technical field of 2-hydroxy-benzonitrile. The process comprises the following steps: adding alkali liquor into the 2-hydroxy-benzonitrile production wastewater, adjusting the pH value of the wastewater, and adding montmorillonite for hydrolysis reaction to obtain a hydrolysis solution; adding an acid solution into the hydrolysis solution to adjust the pH value, stirring to separate out a solid, filtering, washing and drying to obtain salicylic acid; the method comprises the following steps: dissolving salicylic acid in deionized water, introducing a salicylic acid solution and ammonia water into a fixed bed reactor filled with a (BaHPO4) / C (at) A < l > 2O3 catalyst, and purifying a reaction product to obtain the 2-hydroxy-benzonitrile. Under the action of the (BaHPO4) / C (at) A < l > 2O3 catalyst, salicylic acid is converted to prepare the 2-hydroxy-benzonitrile, so that the environmental pollution caused by a large amount of residual wastewater in a 2-hydroxy-benzonitrile production reaction kettle is avoided, and the recycling of resources is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of salicylic nitrile, and in particular relates to a salicylic nitrile kettle residue recovery and treatment process. Background Art

[0002] Salicylonitrile (o-hydroxybenzonitrile) is an important intermediate for medicine, pesticide, fragrance, liquid crystal material, etc., especially the key intermediate for the synthesis of medicine bunilol and fungicide azoxystrobin. There are many methods for synthesizing salicylonitrile, but high-quality salicylonitrile is generally prepared by dehydration after reaction of salicylamide with phosgene. The post-treatment of this method produces corresponding wastewater through alkali dissolution, acid precipitation and water washing. The reactor producing 1t of salicylonitrile will produce 6t~7t of wastewater; at the same time, the residual wastewater in the reactor mainly contains three substances: salicylicamide, salicylic nitrile and salicylic acid, among which the concentration of salicylic amide is 1500ppm~2500ppm, the concentration of salicylic nitrile is 7500ppm~8500ppm, and the concentration of salicylic acid is 100ppm~200ppm. If the wastewater generated in the production process of salicylonitrile is not recycled and treated, it will not only result in a low synthesis yield of salicylonitrile and a large waste of resources, but also have a huge toxic effect on microorganisms in the biochemical system.

[0003] Patent document CN108911973A provides a method for preparing salicylic acid from salicylic nitrile production wastewater, wherein a composite catalyst prepared from rare earth optical glass and montmorillonite is used to catalyze the hydrolysis solution, and then salicylic acid with a yield of more than 80% is obtained through acidification recovery. However, the rare earth materials required for development are expensive, and salicylic acid is not the target product in salicylic nitrile production. Therefore, a cheaper catalytic reaction system is required to recycle salicylic nitrile production wastewater to prepare salicylic nitrile. Summary of the invention

[0004] The purpose of the present invention is to provide a salicylonitrile kettle residue recovery and treatment process to solve the problem that a large amount of waste water remaining in the existing salicylonitrile production reactor causes waste of resources and pollution to the environment.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A salicylic nitrile kettle residue recovery and treatment process comprises the following steps:

[0007] Step 1, adding alkali solution to salicylic nitrile production wastewater, adjusting the pH value of the wastewater to 11-12, adding montmorillonite as a catalyst for hydrolysis reaction, and obtaining a hydrolysis solution;

[0008] Step 2, adding acid solution to the hydrolysis solution to adjust the pH value to 1-2, stirring to precipitate solid, filtering, washing and drying to obtain salicylic acid; repeating steps 1 and 2 for 1-3 times with the filtrate; and combining;

[0009] Step 3, dissolving salicylic acid in deionized water, passing the salicylic acid solution and aqueous ammonia into a fixed bed reactor filled with (BaHPO4) / C@Al2O3 catalyst, reacting at a reaction temperature of 350-400°C and normal pressure, and obtaining salicylic nitrile after purification of the product.

[0010] The preparation method of (BaHPO4) / C@Al2O3 catalyst comprises the following steps:

[0011] S1. Humin is subjected to carbonization treatment to obtain carbonized humin;

[0012] S2. Phosphoric acid and barium hydrogen phosphate were added to deionized water in sequence and mixed to obtain a reaction solution; carbonized humin was added to the reaction solution, stirred for 3-5h, and the humin-loaded barium hydrogen phosphate precursor was collected by filtration;

[0013] S3. The humin-loaded barium hydrogen phosphate precursor was immersed in aluminum chloride solution, ultrasonicated for 3-5 hours at room temperature (25-30°C), the precipitate was collected by centrifugation, and calcined at 85-95°C to obtain the (BaHPO4) / C@Al2O3 catalyst.

[0014] Furthermore, the carbonization pretreatment is specifically to place the humin in a N2 atmosphere and calcine it at 500°C for 5h.

[0015] Furthermore, the usage ratio of the deionized water, phosphoric acid and barium hydrogen phosphate is 100 mL: 4-5 g: 3-5 g.

[0016] Furthermore, the dosage ratio of the reaction solution to carbonized humin is 100 mL: 6-12 g.

[0017] Furthermore, the mass concentration of the aluminum chloride solution is 5%-10%.

[0018] Furthermore, the dosage ratio of the humin-loaded barium hydrogen phosphate precursor and the aluminum chloride solution is 8-15 g:100 mL.

[0019] Furthermore, the alkali solution is a sodium hydroxide solution with a concentration of 0.1-1 mol / L.

[0020] Furthermore, the dosage ratio of the montmorillonite to the alkali solution is 1g:18-22mL.

[0021] Furthermore, the acid solution is a dilute hydrochloric acid solution with a mass concentration of 10%-16%.

[0022] Furthermore, the solute molar ratio of the salicylic acid solution to the ammonia water is 1:8-10.

[0023] Furthermore, the speed of introducing the salicylic acid solution into the fixed bed reactor is 6-10 mL / min; the speed of introducing the ammonia water into the fixed bed reactor is 8-12 mL / min.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a salicylic nitrile kettle residue recovery and treatment process, which uses salicylamide and salicylic nitrile in the residual wastewater in the salicylic nitrile reactor as raw materials, catalytically hydrolyzes them under alkaline conditions, and then washes and precipitates them through acid precipitation to obtain salicylic acid crystals; a fixed bed reactor is used to realize salicylic acid conversion to prepare salicylic nitrile under the action of (BaHPO4) / C@Al2O3 catalyst, thereby avoiding the pollution of the environment caused by a large amount of wastewater remaining in the salicylic nitrile production reactor, and realizing the recycling of resources.

[0026] 2. Since the process of generating salicylic nitrile from salicylic acid includes aminolysis and dehydration reaction, the dehydration of the intermediate salicylamide to generate salicylic nitrile is the key to the reaction rate, and the acidic sites on the catalyst surface are required to react quickly with the carbonyl oxygen of the amide, and the hydrogen connected to the amino group is connected to the basic active site of the catalyst to promote the intramolecular dehydration of salicylic amide. Therefore, the catalyst needs to have suitable acidity and alkalinity, which is conducive to the completion of intramolecular dehydration of the carbon-oxygen double bond of the amide carbonyl. The present invention uses biomass carbon material humin as an intermediate carrier of activated alumina and barium hydrogen phosphate to form a sandwich structure. On the one hand, humin as an intermediate carrier with a certain acidity can regulate the acidity and alkalinity of barium hydrogen phosphate and activated alumina, thereby improving the selectivity of the salicylic acid reaction; at the same time, humin and activated alumina synergistically increase the catalytic active sites and ensure the reaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with the accompanying drawings.

[0028] Figure 1 The present invention is a process flow chart of the recovery and treatment of salicylic nitrile kettle residue. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0030] A method for preparing a (BaHPO4) / C@Al2O3 catalyst comprises the following steps:

[0031] S1. placing humin in a N2 atmosphere and calcining at 500°C for 5h to obtain carbonized humin;

[0032] S2. Phosphoric acid and barium hydrogen phosphate were added to deionized water in sequence and mixed to obtain a reaction solution; carbonized humin was added to the reaction solution, stirred at 300 rpm for 3-5 hours, and the humin-loaded barium hydrogen phosphate precursor was collected by filtration; the amount ratio of deionized water, phosphoric acid and barium hydrogen phosphate was 100 mL: 4-5 g: 3-5 g; the amount ratio of the reaction solution and carbonized humin was 100 mL: 6-12 g;

[0033] S3. The humin-loaded barium hydrogen phosphate precursor is immersed in an aluminum chloride solution with a mass concentration of 5%-10%, ultrasonicated at room temperature for 3-5 hours, centrifuged to collect the precipitate, and calcined at 85-95°C to obtain a (BaHPO4) / C@A l2O3 catalyst. The dosage ratio of the humin-loaded barium hydrogen phosphate precursor and the aluminum chloride solution is 8-15g:100mL.

[0034] Please refer to Figure 1 A salicylic nitrile kettle residue recovery and treatment process comprises the following steps:

[0035] Step 1, adding a NaOH solution with a concentration of 0.1-1 mol / L to salicylic nitrile production wastewater, adjusting the pH value of the wastewater to 11-12, adding montmorillonite as a catalyst for hydrolysis reaction, and obtaining a hydrolysis solution; the dosage ratio of montmorillonite to NaOH solution is 1g:18-22mL;

[0036] Step 2, adding a dilute hydrochloric acid solution with a mass concentration of 10%-16% to the hydrolysis solution to adjust the pH value to 1-2, stirring at a speed of 100 rpm to precipitate solids, filtering, washing and drying to obtain salicylic acid crystals; repeating steps 1 and 2 for 1-3 times with the filtrate; combining;

[0037] Step 3, dissolving salicylic acid crystals in deionized water, passing salicylic acid solution and ammonia water with a solute molar ratio of 1:8-10 into a fixed bed reactor filled with (BaHPO4) / C@Al2O3 catalyst, the speed of passing salicylic acid solution is 6-10mL / min, and the speed of passing ammonia water is 8-12mL / min; reacting at a reaction temperature of 350-400°C and normal pressure, and obtaining salicylonitrile after purification of the product.

[0038] Example 1

[0039] A method for preparing a (BaHPO4) / C@Al2O3 catalyst comprises the following steps:

[0040] S1. placing humin in a N2 atmosphere and calcining at 500°C for 5h to obtain carbonized humin;

[0041] S2. 4.5 g of phosphoric acid and 4 g of barium hydrogen phosphate were added to 100 mL of deionized water, and the mixture was mixed to obtain a reaction solution; 10 g of carbonized humin was added to 100 mL of the reaction solution, and the mixture was stirred at 300 rpm for 4 h, and the humin-loaded barium hydrogen phosphate precursor was collected by filtration;

[0042] S3. Immerse 10 g of humin-loaded barium hydrogen phosphate precursor in 100 mL of 8% aluminum chloride solution, ultrasonicate at room temperature for 4.5 h, collect the precipitate by centrifugation, and calcine at 90°C to obtain the (BaHPO4) / C@Al2O3 catalyst.

[0043] Example 2

[0044] A method for preparing a (BaHPO4) / C@Al2O3 catalyst comprises the following steps:

[0045] S1. placing humin in a N2 atmosphere and calcining at 500°C for 5h to obtain carbonized humin;

[0046] S2. 5 g of phosphoric acid and 5 g of barium hydrogen phosphate were added to 100 mL of deionized water, and the mixture was mixed to obtain a reaction solution; 12 g of carbonized humin was added to 100 mL of the reaction solution, and the mixture was stirred at 300 rpm for 4 h, and the humin-loaded barium hydrogen phosphate precursor was collected by filtration;

[0047] S3. 12 g of humin-loaded barium hydrogen phosphate precursor was immersed in 100 mL of 8% aluminum chloride solution, ultrasonicated at room temperature for 4.5 h, centrifuged to collect the precipitate, and calcined at 90°C to obtain the (BaHPO4) / C@Al2O3 catalyst.

[0048] Example 3

[0049] S1. placing humin in a N2 atmosphere and calcining at 500°C for 5h to obtain carbonized humin;

[0050] S2. 4 g of phosphoric acid and 3 g of barium hydrogen phosphate were added to 100 mL of deionized water, and the mixture was mixed to obtain a reaction solution; 10 g of carbonized humin was added to 100 mL of the reaction solution, and the mixture was stirred at 300 rpm for 4 h, and the humin-loaded barium hydrogen phosphate precursor was collected by filtration;

[0051] S3. Immerse 10 g of humin-loaded barium hydrogen phosphate precursor in 100 mL of 8% aluminum chloride solution, ultrasonicate at room temperature for 4.5 h, collect the precipitate by centrifugation, and calcine at 90°C to obtain the (BaHPO4) / C@Al2O3 catalyst.

[0052] Comparative Example 1

[0053] A method for preparing a (BaHPO4)@Al2O3 catalyst comprises the following steps:

[0054] To 100 mL of deionized water, 4.5 g of phosphoric acid and 4 g of barium hydrogen phosphate were added in sequence and mixed evenly to obtain a reaction solution. 10 g of pseudo-boehmite was added to 100 mL of the reaction solution, and ultrasonic treatment was performed at room temperature for 4.5 h. The precipitate was collected by centrifugation and calcined at 90°C to obtain the (BaHPO4)@Al2O3 catalyst.

[0055] Example 4

[0056] A salicylic nitrile kettle residue recovery and treatment process comprises the following steps:

[0057] Step 1, adding a NaOH solution with a concentration of 0.5 mol / L to salicylic nitrile production wastewater, adjusting the pH value of the wastewater to 11.5, adding montmorillonite as a catalyst for hydrolysis reaction, and obtaining a hydrolysis solution; the dosage ratio of montmorillonite to NaOH solution is 1g:20mL;

[0058] Step 2, adding a 14% dilute hydrochloric acid solution to the hydrolysis solution to adjust the pH value to 1.5, stirring at 100 rpm to precipitate solids, filtering, washing and drying to obtain salicylic acid crystals; repeating steps 1 and 2 twice with the filtrate, and combining;

[0059] Step 3, dissolving salicylic acid crystals in deionized water, and passing salicylic acid solution and ammonia water with a solute molar ratio of 1:9 into a fixed bed reactor filled with the (BaHPO4) / C@Al2O3 catalyst prepared in Example 1, the rate of passing the salicylic acid solution is 8 mL / min, and the rate of passing the ammonia water is 10 mL / min; reacting at a reaction temperature of 380°C and normal pressure, and obtaining salicylonitrile after purification of the product.

[0060] Example 5

[0061] A salicylonitrile kettle residue recovery and treatment process, which differs from Example 4 in that only the (BaHPO4) / C@A l2O3 catalyst prepared by Example 1 in step 3 is replaced by the (BaHPO4) / C@A l2O3 catalyst prepared by Example 2, and the other steps and parameters remain unchanged.

[0062] Example 6

[0063] A salicylonitrile kettle residue recovery and treatment process, which differs from Example 4 in that only the (BaHPO4) / C@A l2O3 catalyst prepared by Example 1 in step 3 is replaced by the (BaHPO4) / C@A l2O3 catalyst prepared by Example 3, and the other steps and parameters remain unchanged.

[0064] Comparative Example 2

[0065] A salicylonitrile kettle residue recovery and treatment process, which differs from Example 4 in that only the (BaHPO4) / C@A l2O3 catalyst prepared by Example 1 in step 3 is replaced by the (BaHPO4) / C@A l2O3 catalyst prepared by Comparative Example 1, and the other steps and parameters remain unchanged.

[0066] The salicylonitrile recovered from Examples 4-6 and Comparative Example 2 was analyzed and tested using a gas chromatograph. The test results are shown in Table 1:

[0067] Table 1

[0068] Salicylic acid conversion rate Salicylonitrile selectivity Salicylic nitrile purity Example 4 99％ 85％ 98％ Example 5 99％ 86％ 97％ Example 6 99％ 84％ 98％ Comparative Example 1 78％ 69％ 84％

[0069] The wastewater generated during the reaction of step 2 and step 3 of Examples 4-6 and Comparative Example 2 were combined and tested. The test results showed that the production wastewater in Examples 4-6 met the discharge standards, while the production wastewater in Comparative Example 1 needed to be further purified.

[0070] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0071] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for recovering and treating salicylic nitrile residue, characterized in that: The following steps are involved: Step 1, adding alkali solution to salicylic nitrile production wastewater, adjusting the pH value of the wastewater to 11-12, adding montmorillonite to carry out hydrolysis reaction, and obtaining a hydrolysis solution; Step 2, adding acid solution to the hydrolysis solution to adjust the pH value to 1-2, stirring to precipitate solid, filtering, washing and drying to obtain salicylic acid; repeating steps 1 and 2 for 1-3 times with the filtrate; and combining; Step 3, dissolving salicylic acid in deionized water, passing the salicylic acid solution and ammonia water into a fixed bed reactor filled with (BaHPO4) / C@Al2O3 catalyst, reacting at a reaction temperature of 350-400°C and normal pressure, and obtaining salicylic nitrile after purification of the product.

2. A salicylic nitrile kettle residue recovery and treatment process according to claim 1, characterized in that: The preparation method of the (BaHPO4) / C@Al2O3 catalyst comprises the following steps: S1. Humin is subjected to carbonization treatment to obtain carbonized humin; S2. Phosphoric acid and barium hydrogen phosphate were added to deionized water in sequence and mixed to obtain a reaction solution; carbonized humin was added to the reaction solution, stirred for 3-5h, and the humin-loaded barium hydrogen phosphate precursor was collected by filtration; S3. The humin-loaded barium hydrogen phosphate precursor was immersed in aluminum chloride solution, ultrasonicated at room temperature for 3-5 hours, centrifuged to collect the precipitate, and calcined at 85-95°C to obtain the (BaHPO4) / C@Al2O3 catalyst.

3. A salicylic nitrile kettle residue recovery and treatment process according to claim 2, characterized in that: The usage ratio of the deionized water, phosphoric acid and barium hydrogen phosphate is 100 mL: 4-5 g: 3-5 g.

4. A salicylic nitrile kettle residue recovery and treatment process according to claim 2, characterized in that: The dosage ratio of the reaction solution to carbonized humin is 100 mL: 6-12 g.

5. A salicylic nitrile kettle residue recovery and treatment process according to claim 2, characterized in that: The mass concentration of the aluminum chloride solution is 5%-10%.

6. A salicylic nitrile kettle residue recovery and treatment process according to claim 2, characterized in that: The dosage ratio of the humin-loaded barium hydrogen phosphate precursor and the aluminum chloride solution is 8-15 g:100 mL.

7. The process for recovering and treating the salicylic nitrile residue according to claim 1, characterized in that: The alkali solution is a sodium hydroxide solution with a concentration of 0.1-1 mol / L; the acid solution is a dilute hydrochloric acid solution with a mass concentration of 10%-16%.

8. The process for recovering and treating the salicylic nitrile residue according to claim 1, characterized in that: The dosage ratio of the montmorillonite to the alkali solution is 1g:18-22mL.

9. A salicylic nitrile kettle residue recovery and treatment process according to claim 1, characterized in that: The solute molar ratio of the salicylic acid solution to the ammonia water is 1:8-10.

10. The process for recovering and treating the salicylic nitrile residue according to claim 1, characterized in that: The salicylic acid solution is introduced into the fixed bed reactor at a rate of 6-10 mL / min; The rate of introducing ammonia water into the fixed bed reactor is 8-12 mL / min.

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