Difluoroethanol preparation apparatus

Abstract

This application provides a difluoroethanol preparation apparatus. An esterification reactor is used to react raw material R142 with potassium acetate to produce an esterified product. A light component removal tower is then used to remove the light components from the esterified product. The light-component esterified product is then distilled to obtain a pure esterified product. This esterified product is then hydrolyzed in a hydrolysis reactor with an alkaline solution to produce difluoroethanol. The hydrolysis reaction solution is then transferred to a distillation reactor to separate the difluoroethanol to obtain crude difluoroethanol. The separated crude difluoroethanol is then purified by a light component removal tower to obtain an aqueous difluoroethanol product. This apparatus, through the combined use of the above equipment, overcomes the problems of complex post-processing and excessive waste generation, which can easily cause pollution, associated with traditional difluoroethanol production methods.

Description

Technical Field

[0001] This application relates to the field of organofluorine chemical technology, and in particular to a difluoroethanol preparation apparatus. Background Technology

[0002] 2,2-Difluoroethanol is an important fluorine-containing intermediate with the molecular formula C₂H₄F₂O and a boiling point of 95.5 °C. It is a colorless liquid with an alcoholic odor at room temperature and is soluble in water, acids, ethanol, and ether. Difluoroethanol has an acidity comparable to phenol. It is stable and does not decompose upon distillation. Difluoroethanol is an intermediate in organic synthesis and can be used as an insecticide and herbicide.

[0003] Currently, difluoroethanol is mainly obtained by reducing fluorinated carboxylic acid esters, fluorinated acyl chlorides, and fluorinated carboxylic acids with reducing agents such as metal borohydrides. This method is simple and has a high yield. However, due to the high price of reducing agents, the violent and unsafe reduction reaction, the difficulty in separating the product from the reducing agent and solvent, the complex post-processing of the product and the large amount of waste, it is easy to cause pollution. Utility Model Content

[0004] This application provides a difluoroethanol preparation apparatus to solve the problems of complex post-processing of products and excessive waste generation and pollution caused by the existing methods for synthesizing 2,2-difluoroethanol.

[0005] This application provides a difluoroethanol preparation apparatus, comprising an esterification kettle, a filter, a crude ester product tank, an ester removal tower, an ester distillation tower, an ester product tank, a hydrolysis kettle, a distillation kettle, a difluoroethanol removal tower, and a difluoroethanol finished product tank connected in series. The esterification reactor is also connected to a solvent storage tank, an R142 storage tank, and a potassium acetate storage tank, respectively. The hydrolysis reactor is also connected to an alkali metering pump.

[0006] Optionally, a separation device is also provided between the difluoroethanol light removal tower and the difluoroethanol finished product tank; The separation unit is also connected to the wastewater pipeline.

[0007] Optionally, the esterification light removal tower is connected to the R142 recovery tank via a condenser; The R142 recovery tank is connected to the esterification reactor; The filter is also connected to a potassium chloride treatment unit.

[0008] Optionally, the esterification distillation column is also connected to a solvent recovery tank; The solvent recovery tank is also connected to the esterification reactor.

[0009] Optionally, the distillation vessel is also connected in sequence to a potassium acetate recovery and treatment device and an esterification vessel; The difluoroethanol light removal tower is also connected to the ester recovery tank. The ester recovery tank is also connected to the hydrolysis reactor.

[0010] Optionally, the potassium acetate recovery and treatment device includes a concentrator, a crystallizer, a filter press, a dryer, and a potassium acetate storage tank.

[0011] Optionally, the separation device is a pervaporation membrane.

[0012] The difluoroethanol preparation apparatus of this application involves reacting raw material R142 and potassium acetate in an esterification reactor to produce an ester. A light component removal tower is then installed to remove the light components from the ester. The purified ester is then distilled to obtain a pure ester. This ester is then hydrolyzed in an alkaline reactor to produce difluoroethanol. The hydrolysate is transferred to a distillation reactor to separate the difluoroethanol, yielding crude difluoroethanol. This crude difluoroethanol is then purified by a light component removal tower to obtain an aqueous difluoroethanol product. The apparatus of this application, using the aforementioned equipment, produces difluoroethanol with an easy-to-operate reaction process, inexpensive and readily available raw materials, and easily recoverable and separable reaction products. This overcomes the problems of complex post-processing and excessive waste, which are common and prone to pollution associated with traditional methods of reducing fluorinated carboxylic esters, fluorinated acyl chlorides, and fluorinated carboxylic acids with metal borohydrides to produce difluoroethanol. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a difluoroethanol preparation apparatus provided in one embodiment of this application; Figure 2 This is a schematic diagram of a difluoroethanol preparation apparatus provided in another embodiment of this application; Figure 3 A schematic diagram of a difluoroethanol preparation apparatus provided in yet another embodiment of this application; Figure 4 This is a schematic diagram of a potassium acetate recovery and treatment device provided in an embodiment of this application.

[0015] Explanation of reference numerals in the attached figures: 1. Esterification kettle; 2. Filter press; 3. Ester removal tower; 4. Esterification distillation tower; 5. Hydrolysis kettle; 6. Distillation kettle; 7. Difluoroethanol removal tower; 8. Difluoroethanol finished product tank; 11. Solvent storage tank; 12. R142 storage tank; 13. Potassium acetate storage tank; 14. R142 recovery tank; 20. Ester crude product tank; 21. Potassium chloride storage silo; 31. Condenser; 40. Ester product tank; 41. Solvent recovery tank; 50. Alkali metering pump; 61. Potassium acetate recovery treatment device; 71. Ester recovery tank; 81. Separation device; 611. Concentrator; 612. Crystallization kettle; 613. Filter press; 614. Dryer; 615. Potassium acetate storage silo; 811. Wastewater pipeline. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0017] like Figure 1 and Figure 2 As shown, this application provides a difluoroethanol preparation apparatus, including an esterification kettle 1, a filter 2, an ester crude product tank 20, an ester removal tower 3, an ester distillation tower 4, an ester product tank 40, a hydrolysis kettle 5, a distillation kettle 6, a difluoroethanol removal tower 7, and a difluoroethanol finished product tank 8, connected in series. Esterification vessel 1 is also connected to solvent storage tank 11, R142 storage tank 12 and potassium acetate storage tank 13 respectively; The hydrolysis vessel 5 is also connected to the alkali metering pump 50.

[0018] The difluoroethanol preparation apparatus of this application involves first adding potassium acetate (dried product, with a moisture content below the company's specified limit) from potassium acetate storage tank 13 to esterification reactor 1. Then, solvent (N-methylpyrrolidone, also known as NMP, is used as the solvent in this application) from solvent storage tank 11 is added to esterification reactor 1. The reactor is then closed, stirring is initiated, nitrogen purging is performed, and heating begins. After reaching a reaction temperature of 150°C, R142 (i.e., 1,1-difluoro-2-chloroethane) from R142 storage tank is slowly introduced into esterification reactor 1 according to a set ratio, and the reaction is maintained at this temperature until the endpoint. After the reaction is complete, the reaction solution is cooled to below 100°C and filtered through filter 2. The filtered reaction liquid (i.e., crude ester) is temporarily stored in crude ester tank 20. Then, the crude ester in crude ester tank 20 is transferred to ester removal tower 3 to remove low-boiling-point materials (mainly R142) from the reaction. The removed material, i.e., the ester solution, is then transferred to esterification distillation tower 4 for distillation. Esters with boiling points lower than the solvent (NMP) (i.e., 2,2-difluoroethyl acetate) are distilled out and simultaneously transferred to ester product tank 40.

[0019] The ester obtained from distillation is then transferred from the ester product tank 40 to the hydrolysis reactor 5, where it reacts with the alkali solution (potassium hydroxide aqueous solution is used in this application) added by the alkali metering pump 50 at 80°C for 3-4 hours. The hydrolysis reaction solution is then sent to the distillation reactor 6 for distillation to remove difluoroethanol and materials with boiling points lower than difluoroethanol. The distilled material is then transferred to the difluoroethanol light removal tower 7 to evaporate and remove the low-boiling-point materials (mainly 2,2-difluoroethyl acetate, boiling point 71.5°C). The resulting difluoroethanol aqueous solution is then transferred to the difluoroethanol product tank 8.

[0020] The difluoroethanol preparation apparatus of this application involves setting up an esterification reactor 1 to react raw material R142 and potassium acetate to produce an ester, followed by a light component removal tower 3 to remove the light components from the ester. The light-component ester is then distilled to obtain a pure ester. This ester is then hydrolyzed in a hydrolysis reactor 5 with an alkaline solution to produce difluoroethanol. The hydrolysis reaction solution is then transferred to a distillation reactor 6 to separate the difluoroethanol into crude difluoroethanol. The separated crude difluoroethanol is then purified by a light component removal tower 7 to obtain an aqueous difluoroethanol product. This apparatus, using the above-mentioned equipment, produces difluoroethanol with an easy-to-operate reaction process, inexpensive and readily available raw materials, and easily recoverable and separable reaction products. It overcomes the problems of complex post-processing and excessive waste, which are prone to pollution, associated with traditional methods using metal borohydrides to reduce fluorinated carboxylic esters, fluorinated acyl chlorides, and fluorinated carboxylic acids to produce difluoroethanol.

[0021] like Figure 3As shown, optionally, a separation device 81 is also provided between the difluoroethanol light removal tower 7 and the difluoroethanol finished product tank 8; The separation device 81 is also connected to the wastewater pipeline 811.

[0022] In this application, since the boiling point of difluoroethanol is 95.5℃ and the boiling point of water is 100℃ under normal pressure, the two boiling points are extremely close. Therefore, the distillation process cannot separate them. Moreover, the light removal process only removes low-boiling-point materials, and the mixture of difluoroethanol and water remains in the bottom liquid of the column. Furthermore, since the boiling points of the two differ by only about 5℃ under normal pressure, it is difficult to separate them by rectification. If pressure rectification is used, the energy consumption will be too high. Therefore, the mixture of difluoroethanol and water is fed into the separation device 81. After the separation operation, the anhydrous difluoroethanol product is obtained at the membrane feed side outlet and stored in the difluoroethanol product tank 8. The permeate side component is condensed and sent to the wastewater pipeline 811 for centralized treatment.

[0023] like Figure 2 and Figure 3 As shown, optionally, the esterification light removal tower 3 is connected to the R142 recovery tank 14 via a condenser 31; R142 recovery tank 14 is connected to esterification kettle 1; Filter 2 is also connected to potassium chloride storage tank 21.

[0024] like Figure 2 and Figure 3 As shown, optionally, the esterification distillation column 4 is also connected to the solvent recovery tank 41; Solvent recovery tank 41 is also connected to esterification vessel 1.

[0025] In this application, because NMP has a high boiling point, the bottom of the column is filled with the high-boiling-point solvent N-methylpyrrolidone. The material from the bottom of the column is transferred to the solvent recovery tank 41 for use in subsequent batches of esterification reaction synthesis.

[0026] like Figure 2 and Figure 3 As shown, optionally, the distillation vessel 6 is also connected in sequence to the potassium acetate recovery and treatment device 61 and the esterification vessel 1; The difluoroethanol light removal tower 7 is also connected to the ester recovery tank 71. The ester recovery tank 71 is also connected to the hydrolysis vessel 5.

[0027] In this application, the hydrolysis reaction solution is fed into distillation vessel 6 for distillation to remove difluoroethanol and materials with boiling points lower than difluoroethanol. The distilled material is then transferred to difluoroethanol removal tower 7, where low-boiling-point materials (mainly 2,2-difluoroethyl acetate, boiling point 71.5℃) are evaporated and removed. The removed 2,2-difluoroethyl acetate (condensed into liquid by the condenser at the top of difluoroethanol removal tower 7) flows into ester recovery tank 71 and is then used in hydrolysis vessel 5 for hydrolysis to produce difluoroethanol. The residue obtained after distillation in distillation vessel 6, i.e., potassium acetate aqueous solution (acetic acid is obtained after ester hydrolysis, and acetic acid reacts with alkali to obtain potassium acetate), is fed into potassium acetate recovery treatment device 61 for treatment. The potassium acetate obtained after treatment can be used in esterification vessel 1 for reaction.

[0028] like Figure 4 As shown, optionally, the potassium acetate recovery and treatment device 61 includes a concentrator 611, a crystallizer 612, a filter press 613, a dryer 614, and a potassium acetate storage tank 615.

[0029] The residue obtained after distillation in distillation vessel 6, namely the potassium acetate aqueous solution (acetic acid is obtained after hydrolysis of ester, and potassium acetate is obtained by reaction of acetic acid with alkaline solution), is fed into potassium acetate recovery and treatment device 61. In this device, the potassium acetate aqueous solution first enters the concentrator 611 (such as a multi-effect evaporator) for concentration. After being concentrated to a certain concentration, the concentrate is transferred to crystallization vessel 612 for crystallization. Then, the crystallized slurry is transferred to filter press 613 for filter pressing to first separate the solid and liquid. The separated solid, namely wet potassium acetate, is transferred to dryer 614 (such as a vacuum drying oven) for drying. The dried potassium acetate is stored in potassium acetate storage silo 615 for esterification process.

[0030] Optionally, the separation device 81 is a pervaporation membrane.

[0031] In this application, the separation device is a pervaporation membrane. During the pervaporation inorganic membrane dehydration process, the aqueous mixed organic solvent is preheated and then enters the feed side of the membrane module, while the permeate side is maintained at a low pressure (absolute pressure below 2000 Pa) using a vacuum method. On the feed side, water molecules preferentially adsorb onto the membrane surface and permeate through the membrane under the pressure difference of water vapor on both sides, vaporizing into water vapor on the permeate side. After the separation operation, anhydrous difluoroethanol is obtained at the membrane feed side outlet and stored in the difluoroethanol product tank, while the permeate side component is condensed and sent to wastewater pipeline 811 for centralized treatment.

[0032] A difluoroethanol preparation apparatus, the working process of which is as follows: In use, first add the potassium acetate (dry, with a moisture content below the company's specified level) from the potassium acetate storage tank 13 to the esterification reactor 1. Then add the solvent (N-methylpyrrolidone, also known as NMP, is used as the solvent in this application) from the solvent storage tank 11 to the esterification reactor 1. Close the reactor, turn on the stirrer, purge with nitrogen, and start heating. After reaching the reaction temperature of 150°C, slowly introduce R142 (i.e., 1,1-difluoro-2-chloroethane) from the R142 storage tank into the esterification reactor 1 according to the specified ratio and maintain the temperature until the endpoint. After the reaction is complete, cool the reaction solution to below 100°C and filter it through the filter 2. Since the salt generated in the reaction is potassium chloride, which is insoluble in organic solvents, the filter cake obtained is also potassium chloride product, which is transferred to the potassium chloride storage silo 21 for recovery.

[0033] The filtered reaction liquid (i.e., crude ester) is temporarily stored in crude ester tank 20. The crude ester from tank 20 is then transferred to ester removal tower 3 to remove low-boiling-point materials (mainly R142) from the reaction. The removed low-boiling-point materials are condensed by condenser 31 and recovered in R142 recovery tank 14, and then used as reaction substrates in esterification reactor 1. The removed material, i.e., the ester solution, is then transferred to esterification distillation tower 4 for distillation. Esters with boiling points lower than the solvent (NMP) (i.e., 2,2-difluoroethyl acetate) are distilled out and simultaneously transferred to ester product tank 40. The bottom of the tower contains the high-boiling-point solvent N-methylpyrrolidone. The bottom material is transferred to solvent recovery tank 41 for use in subsequent batches of esterification reactions.

[0034] The esterified product obtained from distillation is transferred from the esterified product tank 40 to the hydrolysis reactor 5, where it reacts with the alkali solution (potassium hydroxide aqueous solution in this application) added by the alkali metering pump 50 at 80°C for 3-4 hours. The hydrolysis reaction solution is then sent to the distillation reactor 6 for distillation to remove difluoroethanol and materials with boiling points lower than difluoroethanol. The distilled material is then transferred to the difluoroethanol light-removal tower 7, where the low-boiling-point materials (mainly 2,2-difluoroethyl acetate, boiling point 71.5°C) are evaporated and removed. The removed 2,2-difluoroethyl acetate (condensed into liquid by the condenser at the top of the difluoroethanol light-removal tower 7) flows into the esterified product recovery tank 71 and is then used in the hydrolysis reactor 5 for hydrolysis to produce difluoroethanol. A mixture of difluoroethanol and water is obtained in the bottom of the tower.

[0035] Since the boiling point of difluoroethanol is 95.5℃ and that of water is 100℃ at atmospheric pressure, their boiling points are extremely close. Therefore, distillation cannot separate them. Furthermore, the removal of light components only removes the low-boiling-point material, leaving the mixture of difluoroethanol and water in the bottom liquid of the column. Because their boiling points differ by only about 5℃ at atmospheric pressure, rectification is also difficult to separate them. Using pressurized rectification would be too energy-intensive. Therefore, the mixture of difluoroethanol and water is fed into separation device 81. In this application, the separation device is a pervaporation membrane. During the pervaporation inorganic membrane dehydration process, the water-containing mixed organic solvent is preheated and then enters the feed side of the membrane module, while the permeate side is maintained at a low pressure (absolute pressure below 2000 Pa) using a vacuum method. On the feed side, water molecules preferentially adsorb onto the membrane surface and permeate through the membrane under the pressure difference of water vapor on both sides, vaporizing into water vapor on the permeate side. After separation, anhydrous difluoroethanol is obtained at the membrane feed side outlet and stored in the difluoroethanol product tank, while the permeate side component is condensed and sent to wastewater pipeline 811 for centralized treatment.

[0036] The residue obtained after distillation in distillation vessel 6, namely the potassium acetate aqueous solution (acetic acid is obtained after hydrolysis of ester, and potassium acetate is obtained by reaction of acetic acid with alkaline solution), is fed into potassium acetate recovery and treatment device 61. In this device, the potassium acetate aqueous solution first enters the concentrator 611 (such as a multi-effect evaporator) for concentration. After being concentrated to a certain concentration, the concentrate is transferred to crystallization vessel 612 for crystallization. Then, the crystallized slurry is transferred to filter press 613 for filter pressing to first separate the solid and liquid. The separated solid, namely wet potassium acetate, is transferred to dryer 614 (such as a vacuum drying oven) for drying. The dried potassium acetate is stored in potassium acetate storage silo 615 for esterification process.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A difluoroethanol preparation apparatus, characterized in that, It includes an esterification vessel (1), a filter (2), a crude ester product tank (20), an ester removal tower (3), an ester distillation tower (4), an ester product tank (40), a hydrolysis vessel (5), a distillation vessel (6), a difluoroethanol removal tower (7), and a difluoroethanol product tank (8) connected in series. The esterification vessel (1) is also connected to the solvent storage tank (11), the R142 storage tank (12) and the potassium acetate storage tank (13), respectively. The hydrolysis vessel (5) is also connected to an alkali metering pump (50).

2. The difluoroethanol preparation apparatus according to claim 1, characterized in that, A separation device (81) is also provided between the difluoroethanol light removal tower (7) and the difluoroethanol finished product tank (8). The separation device (81) is also connected to the wastewater pipeline (811).

3. The difluoroethanol preparation apparatus according to claim 1, characterized in that, The esterification light removal tower (3) is connected to the R142 recovery tank (14) via a condenser (31); The R142 recovery tank (14) is connected to the esterification vessel (1); The filter is also connected to a potassium chloride storage tank (21).

4. The difluoroethanol preparation apparatus according to claim 1, characterized in that, The esterification distillation column (4) is also connected to the solvent recovery tank (41); The solvent recovery tank (41) is also connected to the esterification vessel (1).

5. The difluoroethanol preparation apparatus according to any one of claims 1 to 4, characterized in that, The distillation vessel (6) is also connected in sequence to the potassium acetate recovery treatment device (61) and the esterification vessel (1); The difluoroethanol light removal tower (7) is also connected to the ester recovery tank (71); The ester recovery tank (71) is also connected to the hydrolysis vessel (5).

6. The difluoroethanol preparation apparatus according to claim 5, characterized in that, The potassium acetate recovery and treatment device (61) includes a concentrator (611), a crystallizer (612), a filter press (613), a dryer (614), and a potassium acetate storage tank (615).

7. The difluoroethanol preparation apparatus according to claim 2, characterized in that, The separation device (81) is a pervaporation membrane.

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