A method for recovering TDA-A kettle residue

Abstract

A highly efficient and environmentally friendly method for the resource recovery of TDA-A residue from the reactor first involves the chemical conversion of chlorodiethylene glycol into easily separable dioxane, followed by solid-liquid separation and distillation purification to recover TDA-A. The process involves precise control of reaction and distillation parameters, and the addition of an acid-binding agent to prevent impurity regeneration, ultimately achieving a TDA-A purity of ≥97%. This process realizes the resource utilization of industrial hazardous solid waste, significantly reduces raw material losses in TDA-A production, offers strong process controllability, and is equipped with comprehensive safety and environmental management measures. Both solid waste and wastewater can be treated in compliance with regulations, meeting the requirements of waste reduction, emission reduction, and circular development in the chemical industry.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical recycling and industrial solid waste resource utilization, specifically involving the recycling technology of distillation kettle residue in the TDA-A production process. Background Technology

[0002] TDA-A's full name is 1-(2-chloroethoxy)-2-methoxyethane (CAS: 52808-36-3, also known as 2-(2-methoxyethoxy)ethyl chloride), with the following structural formula: TDA-A, primarily used as a key organic intermediate, is widely applied in the synthesis of polymer materials and fine chemical products, mainly for the preparation of tris(3,6-dioxane-heptyl)amine. The raw material cost for TDA-A production is relatively high, and the residue generated during production contains a high proportion of effective components. Therefore, efficient recovery of this residue is not only a core requirement for enterprises to reduce costs and increase efficiency, but also aligns with the chemical industry's environmental development direction of "waste reduction, emission reduction, and recycling." TDA-A residue recovery faces two major challenges: first, chlorodiethylene glycol easily decomposes upon heating during distillation, releasing hydrochloric acid, which corrodes equipment and degrades products; second, dichloroethyl ether and TDA-A have similar boiling points, resulting in poor separation efficiency with simple distillation. Direct distillation of the mixed raw materials from the TDA-A residue cannot simultaneously solve both problems: if dichloroethyl ether is removed through distillation, the required heating conditions will promote the decomposition of chlorodiethylene glycol; if low-temperature distillation is used to avoid chlorodiethylene glycol decomposition, dichloroethyl ether, with its similar boiling point, cannot be effectively separated. Existing technologies typically employ direct distillation, which cannot produce qualified products. The purpose of this patent research is to find a way to achieve targeted and efficient recovery of TDA-A from reactor residues and solve the problems of resource waste and environmental hazards. Summary of the Invention

[0003] To address the problems of ineffective recovery of TDA-A residue, resource waste, and environmental hazards in existing technologies, the present invention aims to provide a method for recovering TDA-A residue. This method achieves targeted and efficient recovery of TDA-A from the residue through a combination of chemical conversion and distillation separation. This method overcomes the separation barrier of short-range boiling point impurities through chemical conversion, and achieves targeted recovery of TDA-A through precisely controlled distillation. Simultaneously, it establishes a comprehensive safety operation procedure, environmental treatment standards, and quality control system to ensure process safety, environmental friendliness, and product stability.

[0004] The core idea of ​​this invention is chemical conversion for impurity removal combined with stepwise distillation purification. Through the directional reaction of anhydrous sodium carbonate and chlorodiethylene glycol, it is converted into dioxane, whose boiling point differs significantly from TDA-A, achieving effective separation of impurities and avoiding the separation difficulties of ternary near-boiling mixtures. Subsequent binary vacuum distillation is sufficient for efficient removal of dichloroethyl ether. An acid-binding agent is added to prevent the hydrolysis and regeneration of impurities in the system, and precise control of distillation parameters improves the purity of TDA-A recovery. Simultaneously, solid waste and waste liquid generated during the process are disposed of in compliance with regulations, and quality testing is conducted at key process nodes to ensure that the recovered products meet the raw material standards for workshop production.

[0005] The TDA-A reactor residue recovery method of the present invention includes the following steps: S1. Impurity Chemical Conversion Process: Place the TDA-A reactor residue raw material in a reactor, add anhydrous sodium carbonate solid at 11% of the reactor residue mass, start stirring (speed 200-300 r / min) to fully mix the solid with the reactor residue, and after there are no obvious solid particles, raise the temperature to 130℃ at a heating rate of 5-8℃ / min, maintain this temperature and perform atmospheric distillation for 13 hours. During the distillation process, dioxane and water generated in the system are continuously distilled off, completing the directional conversion of chlorodiethylene glycol. The distillation tail gas is condensed and the distillate is collected. The distillate is a mixture of dioxane and water and is treated in accordance with the organic solvent recovery specifications.

[0006] S2. Solid-liquid separation process: After distillation in S1, the solid-liquid mixture in the reactor is naturally cooled to 40℃, and then filtered and separated using a 200-mesh polytetrafluoroethylene filter cloth under reduced pressure of -0.06~-0.08MPa to obtain filter cake and filtrate. The main components of the filter cake are sodium chloride generated in the reaction and a small amount of anhydrous sodium carbonate that has not been completely reacted. Add twice the mass of primary water to the filter cake, stir to dissolve, and then incinerate according to the industrial solid waste treatment standards.

[0007] S3. Acid-binding agent addition process: Add 2% anhydrous sodium carbonate by weight of the residue in the reactor to the filtrate obtained in S2 as an acid-binding agent, turn on the stirrer (speed 250 r / min) and stir for 15-20 min to completely dissolve the acid-binding agent and evenly disperse it in the filtrate, to prevent the dichloroethyl ether from hydrolyzing and generating hydrogen chloride during the distillation process, and to avoid the hydrogen chloride from reacting with the system components to regenerate chlorodiethylene glycol impurities.

[0008] S4. Distillation and Purification Process: The filtrate after adding the acid-binding agent is transferred to a distillation kettle. The vacuum system is turned on, and the system vacuum is controlled at -0.095MPa. The oil bath temperature is raised to 115℃ at a heating rate of 5℃ / min for vacuum distillation. During the distillation process, the top temperature of the column is monitored in real time. When the top temperature is 90-95℃, the fore-distillate is collected and temporarily stored in a special storage tank. It can be mixed with the remaining raw material of the next batch of TDA-A and then carried out the chemical conversion process of S1 again. When the top temperature stabilizes at 95℃, the collection tank is switched to start collecting the TDA-A product fraction. When the top temperature drops back to 93℃, the distillation is stopped, the vacuum system and oil bath are turned off, and the collected product fraction is the recovered TDA-A finished product. The small amount of residual liquid remaining in the distillation kettle is high-boiling-point impurities and is collected in a special waste liquid tank in accordance with the hazardous waste liquid treatment regulations. The company will then incinerate it. Attached Figure Description

[0009] Figure 1 This is a flowchart of the TDA-A reactor residue recovery process of the present invention. Detailed Implementation

[0010] The present invention will be further illustrated by the following embodiments. It should be understood that the embodiments of the present invention are merely for illustrating the present invention and are not intended to limit the present invention. Therefore, any simple improvements to the present invention under the premise of the method of the present invention are within the scope of protection of the present invention.

[0011] Example 1: Chemical transformation of impurities (sodium carbonate added at 10%) 1000g of TDA-A residue raw material was placed in a reactor, and 100g of anhydrous sodium carbonate solid was added at 10% of the residue mass. After thorough mixing by stirring (250r / min), the temperature was increased to 130℃ at 6℃ / min, and atmospheric distillation was carried out for 13h. After distillation, a sample of the system was taken for testing, and the test results are shown in the table below:

[0012] Results analysis: Adding 10% sodium carbonate by weight of the residue in the reactor was insufficient to completely react the chlorodiethylene glycol, leaving residual chlorodiethylene glycol in the system. This would affect the subsequent distillation and purification of TDA-A. Therefore, adding 10% sodium carbonate is an unqualified process parameter.

[0013] Example 2: Chemical transformation of impurities (sodium carbonate added at 11%) 1000g of TDA-A residue raw material was placed in a reactor, and 110g of anhydrous sodium carbonate solid was added at 11% of the residue mass. After thorough mixing by stirring (250r / min), the temperature was increased to 130℃ at 6℃ / min, and atmospheric distillation was carried out for 13h. After distillation, a sample of the system was taken for testing, and the test results are shown in the table below:

[0014] Results analysis: Adding 11% sodium carbonate by weight of the residue in the reactor completely reacts chlorodiethylene glycol, leaving no chlorodiethylene glycol residue in the system. Dioxane is the directional conversion product, and its boiling point differs significantly from that of TDA-A. It can be effectively separated by subsequent distillation. Therefore, 11% sodium carbonate is the optimal chemical conversion parameter.

[0015] Example 3: Distillation purification (oil bath temperature 125℃) Take 1000g of the residue filtrate from the chemical transformation in Example 2, add 20g of anhydrous sodium carbonate (2% of the residue mass) as an acid-binding agent, and stir for 20 minutes to completely dissolve. Transfer the filtrate to a distillation vessel, control the vacuum at -0.095MPa, raise the oil bath temperature to 125℃ for reduced pressure distillation, collect the TDA-A product fraction when the top temperature reaches 95℃, and stop distillation when the top temperature drops to 93℃. Test the collected TDA-A product, and the test results are shown in the table below:

[0016] Results analysis: When the oil bath temperature is 125℃, the distillation kettle temperature is too high, causing impurities such as dichloroethyl ether in the system to azeotropically with TDA-A and fail to be effectively separated. The purity of TDA-A is 95.52%, which is lower than the purity requirement of ≥97% for raw materials in the workshop. Therefore, the oil bath temperature of 125℃ is an unqualified process parameter.

[0017] Example 4: Distillation purification (oil bath temperature 115℃, optimal process) Take 1000g of the residue filtrate from the chemical transformation in Example 2, add 20g of anhydrous sodium carbonate (2% of the residue mass) as an acid-binding agent, stir for 20min to completely dissolve, and check the pH of the filtrate to be 8.5, which meets the process requirements; transfer the filtrate to a distillation kettle, turn on the vacuum system to stabilize the system vacuum at -0.095MPa, and raise the oil bath temperature to 115℃ at a heating rate of 5℃ / min for vacuum distillation; during the distillation process, collect about 80g of the initial fraction when the top temperature is 90-95℃, and switch to the collection tank to collect the TDA-A product fraction when the top temperature stabilizes at 95℃, and stop the distillation when the top temperature drops back to 93℃, collecting a total of 645.2g of TDA-A product fraction; Step 4: Test the collected TDA-A product, and the test results are shown in the table below:

[0018] Results analysis: When the oil bath temperature is 115℃, the distillation process is stable, and impurities are effectively separated from TDA-A. The recovery rate of TDA-A reaches 64.52%, and the purity is 97.52%. All test indicators meet the raw material standards for workshop production. Therefore, the optimal process conditions for this invention are: 11% sodium carbonate residue by chemical conversion, 2% sodium carbonate as an acid-binding agent, -0.095MPa vacuum, and 115℃ oil bath distillation.

[0019] Finally, it should be noted that the above embodiments are merely illustrative of several implementations of the present invention and are not intended to limit the scope of the invention. For those skilled in the art, any modifications, equivalent substitutions, or improvements made without departing from the concept of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for recovering TDA-A reactor residue, characterized in that, The TDA-A residue contains TDA-A, chlorodiethylene glycol, dichloroethyl ether, dioxane, and monomethyl ether. The method includes the following steps: S1. Take the TDA-A reactor residue raw material, add anhydrous sodium carbonate at 11% of the reactor residue mass, heat to 130℃ for atmospheric distillation, distill off the dioxane and water generated in the system, and complete the chemical transformation of impurities; S2. Cool the remaining solid-liquid mixture after distillation of S1 to 40°C and separate by filtration; S3. Add 2% (by weight of residual mass) of anhydrous sodium carbonate to the filtrate obtained in S2 as an acid-binding agent, and purify by distillation under vacuum conditions of -0.095 MPa and oil bath at 115 °C. S4. During the distillation process, the TDA-A product fraction is collected when the top temperature stabilizes at 95℃, and collection is stopped when the top temperature drops back to 93℃, thus obtaining the TDA-A recovered product.

2. The method according to claim 1, characterized in that, The heating rate for atmospheric distillation described in S1 is 5-8℃ / min, and the stirring rate of the system is maintained at 200-300r / min during the distillation process.

3. The method according to claim 1, characterized in that, The filtration described in S2 adopts a reduced pressure filtration method, the filter material is 200-mesh polytetrafluoroethylene filter cloth, and the filtration pressure is -0.06~-0.08MPa.

4. The method according to claim 1, characterized in that, In step S2, filtration separates the filter cake and filtrate. The filter cake is a mixture of sodium chloride and a small amount of unreacted sodium carbonate.

5. The method according to claim 1, characterized in that, The acid-binding agent described in S3 is anhydrous sodium carbonate. After addition, the stirring time is 15-20 minutes and the stirring rate is 250 r / min to ensure that the acid-binding agent can be uniformly dispersed in the filtrate.

6. The method according to claim 1, characterized in that, When the top temperature of S4 is 90-95℃, the fore-fraction is collected and temporarily stored. It can be mixed with the next batch of TDA-A reactor residue and then carried out again in the chemical conversion process of S1.

7. The method according to claim 1, characterized in that, After the distillation in S4 is completed, the small amount of residual liquid remaining in the distillation vessel is high-boiling-point impurity.

8. The method according to any one of claims 1-7, characterized in that, Throughout the process, the reaction temperature, distillation time, distillation vacuum, and top temperature must be monitored in real time, with deviations controlled within ±2℃, ±0.5h, and ±0.002MPa, respectively.

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