Device and method for treating 2-hydroxy-benzonitril mother liquor

Abstract

The invention belongs to the technical field of organic chemical industry, and particularly relates to a 2-hydroxy-benzonitril mother liquor treatment device and a method thereof.The method comprises the following steps that 2-hydroxy-benzonitril mother liquor is poured into an alkaline hydrolysis kettle, alkaline liquor is added, stirring is conducted through a liquid separation device for a period of time, then standing is conducted for a period of time, and liquid is layered; enabling lower-layer wastewater to enter a wastewater cryogenic kettle through a liquid separation device, and enabling upper-layer toluene to enter a toluene intermediate tank; mixing the neutralized cryogenic wastewater with the lower-layer water phase of the mother liquor, controlling the pH value to be less than 4, and performing cryogenic crystallization and filtration to obtain a recycled material; the recycled material enters a light-permeable kettle, toluene phosgene is proportioned according to the ingredients of the light-permeable kettle, and salicylamide is converted into 2-hydroxy-benzonitrile through a light-permeable reaction. The reaction temperature is 85-110 DEG C. According to the scheme, the problem of efficient utilization of the 2-hydroxy-benzonitril mother liquor is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic chemical industry, and particularly relates to a device and a method for treating a salicylonitrile mother liquor. Background Art

[0002] In recent years, the continuous synthesis of salicylonitrile by using methyl salicylate, ammonia or urea as raw materials through solid acid heterogeneous catalysis has been reported (Z.J. Kong, et al., Chemical Papers, 2022, 76, 1365–1375; Chen Guanhu et al., Modern Chemical Industry, 2020, 40, 3: 143-151; CN 104549378 A; Chen Erzhong et al., Pesticides, 2018, 57, 27: 870-872). The yield of salicylonitrile obtained by this synthesis method can reach 80-90%, but by-products such as phenol, salicylamide and methanol are generated during the reaction process. At present, no special technology for separating and purifying each component in the above mixture has been reported. Therefore, providing a new separation and purification process is a technical problem that needs to be solved urgently by those skilled in the art, and at the same time lays a foundation and provides technical support for the development of a complete set of industrial technologies for continuous catalytic synthesis and separation of salicylonitrile.

[0003] At present, a salicylonitrile separation and purification process and system with the publication number of CN117185959A on the market includes a mixture of methyl salicylate, phenol, salicylonitrile and salicylamide, and goes through steps such as ammonolysis reaction, distillation, dissolution, filtration, recrystallization, washing and drying. This invention can be used for separating and purifying salicylonitrile products, and at the same time recovering methanol, toluene, phenol and salicylamide.

[0004] However, there are also some problems. 1. In this scheme, toluene is recovered by vacuum distillation to remove the solvent, and the distillation residue is treated with alkali to recover the product, and the residue after secondary distillation is used as hazardous waste. Treating the salicylonitrile mother liquor by distillation has high energy consumption, and salicylonitrile and salicylamide in the residue are used as hazardous waste together with impurities, resulting in waste of resources. 2. When separating toluene, it is separated by density stratification, but after stratification, toluene cannot be accurately separated. The existing method is to separate by adding a partition board, but toluene and the residue are toxic, and it is very dangerous to insert the partition board manually. Summary of the Invention

[0005] The present invention provides a device and a method for treating a salicylonitrile mother liquor to solve the problem of efficient utilization of the salicylonitrile mother liquor.

[0006] This solution provides a device and a method for treating a salicylonitrile mother liquor, including the following steps:

[0007] Step S10: Pour the salicylonitrile mother liquor into the alkali hydrolysis kettle, add alkali solution, stir through the liquid separation device, and after a period of time, let it stand for a period of time to make the liquid layer; Then, through the liquid separation device, the lower-layer wastewater enters the wastewater deep cooling kettle, and the upper-layer toluene enters the toluene intermediate tank;

[0008] Step S20: Neutralize the deep-cooled wastewater and mix it with the lower-layer aqueous phase of the mother liquor, control the pH to <4, filter by deep-cooled crystallization to obtain the recycled material;

[0009] Step S30: The recycled material enters the light-passing kettle, and phosgene is prepared with toluene according to the light-passing kettle batching ratio, and salicylamide is converted into salicylonitrile through the light-passing reaction; The reaction temperature is 85-110 °C.

[0010] The beneficial effects of this solution are as follows: A brand-new method for treating salicylonitrile mother liquor is proposed. This method is simple and effective and can quickly treat the mother liquor. The recycled material is recycled, the material collection is improved, the hazardous waste is converted into products, and the economic benefits are increased; The process hazardous waste in the distillation link is eliminated; The consumption of public auxiliary facilities such as steam, nitrogen, brine, and circulating water is reduced, and the energy consumption is lowered.

[0011] Further, the toluene in step S30 can use the toluene extracted in step S10. This enhances the recycling of materials and saves resources.

[0012] Further, the alkali solution in step S10 is a sodium hydroxide solution with a concentration of 5-20%. The sodium hydroxide solution at this concentration reacts more thoroughly with the salicylonitrile mother liquor.

[0013] A device for treating salicylonitrile mother liquor includes an alkali hydrolysis kettle, a toluene intermediate tank, a light-passing kettle, and a deep-cooled crystallization tank; The alkali hydrolysis kettle includes a kettle body and a liquid separation device. The kettle body is provided with a feed inlet, a first discharge port, and a second discharge port. The liquid separation device includes a motor, a main shaft, an airbag, and a magnetic ball. The motor is fixedly connected to the kettle body, the shaft of the motor is fixedly connected to the main shaft, there are multiple airbags, and they are fixedly connected to the main shaft in a circumferential distribution. The magnetic ball is located inside the airbag, and the airbag is provided with a placement groove, and the placement groove is located at the end of the airbag;

[0014] The first discharge port is communicated with the deep-cooled crystallization tank, the second discharge port is communicated with the toluene intermediate tank, and both the deep-cooled crystallization tank and the toluene intermediate tank are communicated with the light-passing kettle.

[0015] First, pump the salicylonitrile mother liquor into the alkali hydrolysis kettle and add alkali solution. In the initial state, the airbag is in a completely floating state, and the magnetic ball is close to the main shaft. At this time, the operator starts the motor to make the airbag rotate in the liquid, but the rotation speed is not fast, so that the airbag will be in an inclined state, playing a stirring role, and stirring for 0.5 hours.

[0016] When static settlement is required, the operator stops the motor and allows for static settlement for 0.5 hours. After the liquid layers separate, the airbag is located at the separation point. Then the operator restarts the motor. At this time, the motor speed is very fast, causing the magnetic balls in the airbag to quickly reach the end of the airbag under the action of a large centrifugal force and snap into the placement groove. The placement groove is stretched, increasing the contact area of the airbag. Moreover, the magnetic balls will adsorb onto the iron-made kettle body. All the airbags form a plane. Then the motor is immediately turned off, and the upper and lower layers of liquid are separated. At this time, the operator opens the first discharge port, and the lower-layer wastewater enters the wastewater cryogenic kettle. The operator opens the second discharge port, and the upper-layer toluene enters the toluene intermediate tank for use in the light-passing kettle batching.

[0017] Then, after neutralizing and cryogenically cooling the lower-layer wastewater photochemical solution, the lower-layer wastewater is collected in the wastewater tank and pumped into the wastewater cryogenic kettle to be mixed with the mother liquor deep alkaline hydrolysis wastewater. The pH value is controlled to be < 4, and cryogenic filtration is carried out. The filtered material is used as recycled material, and the wastewater enters the wastewater treatment device.

[0018] The dedicated light-passing kettle for recycled material is charged with toluene and recycled material and light-passing gas. A salicylamide content of < 0.2% is considered qualified. The recycled material is converted into a product.

[0019] Furthermore, the airbag is in the shape of a long cone, and the density of the airbag is 0.6 - 0.8 g / cm 3 The airbag of this shape is more likely to form a plane, increasing the sealing performance after layering.

[0020] Furthermore, the kettle body of the alkaline hydrolysis kettle includes a cylinder body and a cylinder cover. The cylinder body and the cylinder cover are fixedly connected by bolts and gaskets. Since these liquids are harmful to the human body, a sealing structure is adopted during the reaction. At the same time, the cylinder cover can also be opened for convenient cleaning. Description of the Drawings

[0021] Figure 1 It is a structural diagram of the alkaline hydrolysis kettle of a salicylonitrile mother liquor treatment device during stirring,

[0022] Figure 2 It is a structural diagram of the alkaline hydrolysis kettle of a salicylonitrile mother liquor treatment device during static settlement,

[0023] Figure 3 It is a structural diagram of the liquid separation device of a salicylonitrile mother liquor treatment device,

[0024] Figure 4 It is a structural diagram of the bottom of the liquid separation device of a salicylonitrile mother liquor treatment device.

[0025] The reference numerals in the specification drawings include: 1. Kettle body; 2. First feed port; 3. Discharge port; 4. Motor; 5. Main shaft; 6. Magnetic ball; 7. Airbag; 8. Placement groove; 9. Outer cladding; 10. Second discharge port. Detailed Embodiments

[0026] Basically as attached Figure 1 shown as follows:

[0027] This solution provides a device and method for treating salicylonitrile mother liquor, including the following steps:

[0028] Step S10: Pour 3800 L of salicylonitrile mother liquor into the alkali hydrolysis kettle, add alkali liquor, the alkali liquor is a 5-20% aqueous sodium hydroxide solution, stir through a liquid separation device for 0.5 hours, and then stand still for 0.5 hours to make the liquid layer. At this time, the density of the upper toluene is about 0.8 g / cm3, and the density of the lower solution is about 1.1 g / cm3. Then, through the liquid separation device, the lower wastewater enters the wastewater deep cooling kettle, and the upper toluene enters the toluene intermediate tank;

[0029] Step S20: Neutralize the deep-cooled wastewater and mix it with the lower aqueous phase of the mother liquor, control the pH to < 4, and perform deep-cooled crystallization filtration to obtain the recycled material;

[0030] Step S30: The recycled material enters the light-passing kettle, and toluene phosgene is prepared according to the light-passing kettle batching ratio. Through the light-passing reaction, salicylamide is converted into salicylonitrile. The reaction temperature is 85-110 °C.

[0031] The beneficial effects of this solution are as follows: A brand-new method for treating salicylonitrile mother liquor is proposed. This method is simple and effective, and can quickly treat the mother liquor. The recycled material is recycled to improve the recovery rate. Hazardous waste is converted into products, increasing economic benefits; the process hazardous waste in the distillation link is eliminated; the consumption of public auxiliary facilities such as steam, nitrogen, brine, and circulating water is reduced, and energy consumption is lowered.

[0032] The toluene in Step S30 can use the toluene extracted in Step S10. This enhances the recycling of materials and saves resources.

[0033] As Figure 1 、 Figure 3 、 Figure 4 shown as follows:

[0034] A device for treating salicylonitrile mother liquor includes an alkali hydrolysis kettle, a toluene intermediate tank, a light-passing kettle, and a deep-cooled crystallization tank; the alkali hydrolysis kettle includes a kettle body 1 and a liquid separation device. The kettle body 1 is provided with a feed inlet 2, a first discharge port 3, and a second discharge port 10. The liquid separation device includes a motor 4, a main shaft 5, an airbag 7, and a magnetic ball 6. The motor 4 is fixedly connected to the kettle body 1, the shaft of the motor 4 is fixedly connected to the main shaft 5. A plurality of airbags 7 are provided and are fixedly connected to the main shaft 5 in a circumferential manner. The magnetic ball 6 is located inside the airbag 7. The airbag 7 is provided with a placement groove 8, and the placement groove 8 is located at the end of the airbag 7. An outer wrapping layer 9 is provided around the airbag 7. When the magnetic ball 6 falls into the placement groove 8, the magnetic ball 6 pulls the placement groove 8 outwards, and at this time, the outer wrapping layer 9 will be pulled, causing the outer layer 9 to turn outwards, increasing the shielding area and making the formed disc tighter.

[0035] The first discharge port 3 is communicated with a cryogenic crystallization tank, the second discharge port 10 is communicated with a toluene intermediate tank, and both the cryogenic crystallization tank and the toluene intermediate tank are communicated with a light-passing kettle.

[0036] The airbag is in a long strip conical shape, and the density of the airbag is 0.6 - 0.8 g / cm 3 . The airbag of this shape is more likely to form a plane, increasing the sealing performance after layering.

[0037] As shown in Figure 1 , Figure 2 , Figure 3 :

[0038] First, the salicylonitrile mother liquor is pumped into an alkali hydrolysis kettle, and an alkali solution is added. In the initial state, the airbag 7 is in a completely floating state, and the magnetic ball 6 is close to the main shaft 5. At this time, the operator starts the motor 4, so that the airbag 7 rotates in the liquid, but the rotation speed is not fast, making the airbag 7 in an inclined state, playing a stirring role, and stirring for 0.5 hours.

[0039] When static settlement is required, the operator stops the motor 4, and static settlement is carried out for 0.5 hours. After the liquid is layered, the airbag 7 is at the layering position. Then the operator starts the motor 4 again. At this time, the rotation speed of the motor 4 is very fast, so that the magnetic ball 6 in the airbag 7 quickly comes to the end of the airbag 7 under the action of a large centrifugal force and is stuck into the placement groove 8. The placement groove 8 is stretched, making the contact area of the airbag 7 larger, and the magnetic ball 6 will adsorb on the iron-made kettle body 1. All the airbags 7 form a plane, and then the motor 4 is immediately turned off to separate the upper liquid and the lower liquid. At this time, the operator opens the first discharge port 2, and the lower-layer wastewater enters the wastewater cryogenic kettle. The operator opens the second discharge port 10, and the upper-layer toluene enters the toluene intermediate tank for light-passing kettle batching.

[0040] Then, after the lower-layer wastewater photochemical solution is neutralized and cryogenically cooled, the lower-layer wastewater is collected in a wastewater tank, pumped into the wastewater cryogenic kettle and mixed with the mother liquor deep alkali hydrolysis wastewater, and the pH value is controlled to be < 4, and cryogenic filtration is carried out. The filter material is used as recycled material, and the wastewater enters the wastewater treatment device.

[0041] The recycled material dedicated light-passing kettle is charged with toluene and the recycled material and light-passing gas. When the salicylamide is < 0.2%, it is qualified. The recycled material is converted into a product.

[0042] The kettle body of the alkali hydrolysis kettle includes a cylinder body and a cylinder cover. The cylinder body and the cylinder cover are fixedly connected by bolts and gaskets. Since these liquids are harmful to the human body, a sealing structure is adopted during the reaction, and the cylinder cover can also be opened for convenient cleaning.

[0043] The above are only embodiments of the present invention, and common knowledge such as specific structures and characteristics known in the art are not described in detail herein. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope claimed in this application shall be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A method for treating the mother liquor of salicylonitrile, characterized in that, It includes the following steps: Step S10: Pour the salicylonitrile mother liquor into an alkali hydrolysis kettle, add an alkali solution, stir through a liquid separation device, and after a period of time, let it stand for another period of time to make the liquid layer. Then, through the liquid separation device again, the lower-layer wastewater enters the wastewater deep-freezing kettle, and the upper-layer toluene enters the toluene intermediate tank; Step S20: Neutralize the deep-frozen wastewater and mix it with the lower-layer aqueous phase of the mother liquor, control the pH to <4, perform deep-frozen crystallization filtration to obtain the recycled material; Step S30: The recycled material enters the light-passing kettle, and phosgene is prepared with toluene according to the light-passing kettle ingredient ratio. Convert salicylamide to salicylonitrile through a light-passing reaction; the reaction temperature is 85-110°C.

2. The method for treating the mother liquor of salicylonitrile according to claim 1, characterized in that, The toluene in step S30 can use the toluene extracted in step S10.

3. The method for treating the salicylonitrile mother liquor according to claim 1, wherein, The alkali solution in step S10 is a sodium hydroxide solution with a concentration of 5-20%.

4. A device for treating the mother liquor of salicylonitrile, characterized in that, It includes an alkali hydrolysis kettle, a toluene intermediate tank, a light-passing kettle, and a deep-frozen crystallization tank; the alkali hydrolysis kettle includes a kettle body (1) and a liquid separation device. The kettle body (1) is provided with a feed inlet (2), a first discharge port (3), and a second discharge port (10). The liquid separation device includes a motor (4), a main shaft (5), an airbag (7), and a magnetic ball (6). The motor (4) is fixedly connected to the kettle body (1). The shaft of the motor (4) is fixedly connected to the main shaft (5). A plurality of airbags (7) are provided and are fixedly connected to the main shaft (5) in a circumferential manner. The magnetic ball (6) is located inside the airbag (7). The airbag (7) is provided with a placement groove (8), and the placement groove (8) is located at the end of the airbag (7); The first discharge port (3) is communicated with the deep-frozen crystallization tank, the second discharge port (10) is communicated with the toluene intermediate tank, and both the deep-frozen crystallization tank and the toluene intermediate tank are communicated with the light-passing kettle.

5. The salicylonitrile mother liquor treatment device according to claim 4, wherein The airbag (7) is long and conical, and the density of the airbag (7) is 0.6 - 0.8 g / cm 3 .

6. The processing device for the salicylonitrile mother liquor according to claim 4, wherein, The alkali hydrolysis kettle body (1) includes a cylinder body and a cylinder cover, and the cylinder body and the cylinder cover are fixedly connected by bolts and gaskets.

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