Process and device for recovering sodium bromide waste liquid in production process of 2-bromo-3, 3, 3-trifluoropropene

Abstract

The invention designs a process and a device for recovering sodium bromide waste liquid, which are used for recovering the sodium bromide waste liquid generated after the reaction of 1, 2-dibromo-3, 3, 3-trifluoropropane and sodium hydroxide involved in the elimination reaction section in the production process of 2-bromo-3, 3, 3-trifluoropropene. The recovery process route is divided into two routes, one route is used for extracting and collecting bromine, and the other route is used for recovering sodium hydroxide. When bromine extraction is carried out, excessive hydrochloric acid is added into the sodium bromide waste liquid which is alkaline and has excessive sodium hydroxide residues for acidification, the acidified solution is subjected to ion exchange, chloride ions are separated, chlorine is generated through electrolysis, and bromide ions and sodium ions are separated through ion exchange resin. Chlorine generated by electrolysis is used for replacing bromine ions in the solution to obtain elemental bromine, meanwhile, the flow of the reaction chlorine is adjusted through a gas flow adjusting valve, and the rate of the replacement reaction and the yield of the elemental bromine are controlled. And electrolyzing, evaporating and crystallizing the separated sodium ion solution to obtain a sodium hydroxide solid. In the recovery process, the product generated in the reaction process is recycled, no excessive pollutant is discharged, the environment is prevented from being damaged, and the recovery process is a green reaction route.

Description

Technical Field

[0001] The invention discloses a sodium bromide waste liquid recovery process and a device, and specifically relates to a sodium bromide waste liquid recovery process and a device in the production process of 2-bromo-3,3,3-trifluoropropene. Background Art

[0002] Under different reaction paths, the raw materials used in the preparation and production of 2-bromo-3,3,3-trifluoropropene are different, but in general, no matter which reaction path is taken, its synthesis process needs to be carried out according to the addition reaction, elimination reaction, distillation reaction and other sections. Therefore, in the process of large-scale production of 2-bromo-3,3,3-trifluoropropene, its production cost comes from the necessary reaction equipment, energy consumption, labor, etc., and the key lies in the selection and utilization of raw materials. If the raw materials are reasonably recovered, the cost is bound to be greatly reduced. For the process improvement of producing 2-bromo-3,3,3-trifluoropropene, the present invention is based on the synthetic reaction path of selecting trifluoropropene, bromine, and sodium hydroxide as raw materials, and the sodium bromide waste liquid generated in the elimination reaction section under this path is processed to extract and recover bromine and sodium hydroxide, the collected bromine is used in the addition reaction section, and the sodium hydroxide is used in the elimination reaction section, so as to realize the recycling of raw materials, reduce the emission of pollutants, and protect the environment. Under this design process, according to the reaction equations of the addition section and the elimination section, the expected effect of bromine recovery that can be achieved (calculated based on a yield of 100%) is as follows: (1) Addition reaction section:

[0003] The production of 1000 kg of 1,2-dibromo-3,3,3-trifluoropropane consumes 625 kg of bromine; (2) Elimination reaction section:

[0004] After the reaction of 1000kg 1,2-dibromo-3,3,3-trifluoropropane is completed, 312kg bromine can be recovered; (3) The reaction actually consumed 313 kg of bromine, with a bromine recovery rate of 50%. Resources were rationally utilized, greatly reducing the cost of raw materials and pollutant emissions. Summary of the invention

[0005] The invention is designed to include a sodium bromide waste liquid recovery process and a device produced by the reaction of 1,2-dibromo-3,3,3-trifluoropropane and sodium hydroxide, and bromine and sodium hydroxide are extracted and recovered.

[0006] The extraction and collection routes of bromine include acidification, ion exchange, electrolysis, displacement, evaporation, adsorption purification, and condensation.

[0007] The extraction and collection device of bromine is an acidification tank, a hydrochloric acid storage tank, a metering pump, an ion exchange chamber, an electrolysis chamber, an ion exchange chamber, a bromide ion enrichment chamber, an evaporator, an adsorption tower, and a condenser. The hydrochloric acid storage tank is connected to the metering pump to control the rate and amount of hydrochloric acid added to the acidification tank. In the ion exchange chamber, the chloride ions in the acidification solution are separated by ion exchange resin and enter the chloride ion enrichment chamber for collection. The electrolysis chamber is divided into an anode area and a cathode area. The anode area is equipped with a chlorine separator to collect the chlorine generated by electrolysis and enter the chlorine storage tank for storage. The cathode area is equipped with a hydrogen separator to collect the hydrogen generated by electrolysis, and the hydrogen is purified and then stored in the hydrogen storage tank. The ion exchange chamber uses ion exchange resin to separate bromide ions and sodium ions. The separated bromide ion solution enters the bromide ion enrichment chamber to undergo a replacement reaction with chlorine. The bromine element obtained by substitution is further separated from the sodium ion and chloride ion solution by a liquid-liquid separator. The bromine gas after the bromine element is vaporized in the evaporator enters the adsorption tower for purification and is finally sent to the condenser to be condensed into liquid bromine.

[0008] The recovery route of sodium hydroxide includes liquid-liquid separation, electrolysis, and evaporative crystallization.

[0009] The sodium hydroxide recovery device includes a liquid-liquid separator, a sodium ion enrichment chamber, an electrolysis chamber, and an evaporator. The liquid-liquid separator separates the layered bromine element from the sodium ion and chloride ion solutions. The separated sodium ion solution enters the sodium ion enrichment chamber, where the sodium ion solution is electrolyzed. The electrolyzed solution is sent to the evaporator for evaporation and crystallization, and the obtained sodium hydroxide solid enters the sodium hydroxide storage chamber for collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 :Process route Figure 2 :Reaction device Markings in the figure: 1 metering pump, 2 sedimentation tank, 3 multi-stage adsorption tower, 4 acidification tank, 5 hydrochloric acid storage tank, 6 metering pump, 7 ion exchange chamber, 8 chloride ion enrichment chamber, 9 electrolysis chamber, 10 chloride ion inspection area, 11 chlorine storage tank, 12 hydrogen purifier, 13 hydrogen storage tank, 14 ion exchange chamber, 15 sodium ion enrichment chamber, 16 bromide ion enrichment chamber, 17 gas flow regulating valve, 18 bromide ion inspection area, 19 liquid-liquid separator, 20 evaporator, 21 adsorption tower, 22 condenser, 23 bromine purity inspection area, 24 gate valve, 25 liquid bromine storage tank, 26 gate valve, 27 electrolysis chamber, 28 hydrogen purifier, 29 hydrogen storage tank, 30 evaporator, 31 sodium hydroxide collector Specific embodiments

[0011] This design divides the sodium bromide waste liquid treatment and recovery process in the production process of 2-bromo-3,3,3-trifluoropropene into two process routes, one is the extraction and collection of bromine, and the other is the recovery of sodium hydroxide. The process flow is as follows: The sodium bromide waste liquid after the reaction is transported to the sedimentation tank 2 by the metering pump 1, so that the high-temperature waste liquid is naturally cooled to room temperature, and at the same time, the water-insoluble organic matter in the waste liquid is settled to the bottom of the tank and filtered out.

[0012] The filtered solution in (1) is passed through a multi-stage adsorption tower 3 for impurity removal. An adsorbent with high adsorption performance, such as activated carbon, is placed in the adsorption tower to further remove organic impurities in the solution.

[0013] The solution is transported to the acidification tank 4, and the metering pump 6 is turned on to transport excess hydrochloric acid solution from the hydrochloric acid storage tank 5 to the acidification tank 4 to consume the excess sodium hydroxide added during the reaction (to eliminate the excess sodium hydroxide when 1,2-dibromo-3,3,3-trifluoropropane reacts with sodium hydroxide in the reaction section) to make the solution acidic.

[0014] The acidified solution enters the ion exchange chamber 7, where the chloride ions are separated by ion exchange resin, and enters the chloride ion enrichment chamber 8 for collection to obtain a chloride ion solution. The chloride ion solution in the chloride ion enrichment chamber 8 is transported to the electrolysis chamber 9 for electrolysis. The anode area of ​​the electrolysis chamber 9 is equipped with a chlorine separator to collect the chlorine generated by electrolysis and enter the chlorine storage tank 11 for storage, and the cathode area is equipped with a hydrogen separator to collect the hydrogen generated by electrolysis, and the hydrogen is purified in the hydrogen purifier 12 and then stored in the hydrogen storage tank 13. The hydrogen purifier 12 is equipped with an active adsorbent with high gas selectivity to remove a small amount of gas impurities such as Cl2, N2, O2, and HCl in the hydrogen component. During the electrolysis process, the solution is tested in the chloride ion test area 10. When no chloride ions are detected in the solution, the electrolysis of the solution is stopped in time.

[0015] The solution separated by the ion exchange chamber 7 is transported to the ion exchange chamber 14 to further separate the sodium ions and bromide ions into the sodium ion enrichment chamber 15 and the bromide ion enrichment chamber 16 for collection. The gas flow regulating valve 17 is opened, and the chlorine is released from the chlorine storage tank 11 and passed into the bromide ion enrichment chamber 16 for reaction to replace the bromine element. During the reaction, the solution is tested for the presence of bromide ions in the bromide ion test area 18. When no bromide ions are detected in the solution, the gas flow regulating valve 17 is closed to stop the introduction of chlorine into the bromide ion enrichment chamber 16; the advantage of this step is that by adjusting the gas flow regulating valve 17, the reaction rate and the quality of the bromine element obtained by replacement can be controlled, and the chlorine required for the reaction comes from the electrolysis process, which effectively avoids the safety risks caused by storing chlorine.

[0016] After the reaction of solution (5) is completed, it is transported to liquid-liquid separator 19 to separate the bromine element from the chloride ion and sodium ion solution, and the chloride ion and sodium ion solution are transferred to sodium ion enrichment chamber 15, and the replaced bromine element enters evaporator 20; at the same time, hydrogen is transported from hydrogen storage tank 13 as fuel for evaporator 20 to supply the required heat; the bromine element in evaporator 20 is evaporated into bromine gas and then enters adsorption tower 21 for impurity removal and purification, and then condensed into liquid bromine by condenser 22. The obtained liquid bromine is tested for purity in bromine purity testing area 23. If the purity meets the production standard, gate valve 24 is opened to transport the liquid bromine to liquid bromine storage tank 25 for collection; if the purity does not meet the production standard, gate valve 26 is opened to transport the liquid bromine back to adsorption tower 21 for purification.

[0017] The solution is transported from the sodium ion enrichment chamber 15 to the electrolysis chamber 27. The anode area of ​​the electrolysis chamber 27 is equipped with a chlorine separator to collect the chlorine generated by electrolysis and enter the chlorine storage tank 11 for storage. The cathode area is equipped with a hydrogen separator to collect the hydrogen generated by electrolysis, and the hydrogen is purified in the hydrogen purifier 28 and stored in the hydrogen storage tank 29. The solution after electrolysis in the electrolysis chamber 27 enters the evaporator 30, and the solution is evaporated and crystallized to obtain sodium hydroxide crystals. The obtained sodium hydroxide solid is stored in the sodium hydroxide collector 31. At the same time, hydrogen is transported from the hydrogen storage tank 29 as fuel for the evaporator 30 to supply the required heat. The advantage of this step is that hydrogen is used as the fuel for the evaporator, and high heat can be generated during the combustion process without any pollutants, while realizing the recycling of resources.

Claims

1. A process for recovering sodium bromide waste liquid in the production process of 2-bromo-3,3,3-trifluoropropene, characterized in that: The invention comprises a sodium bromide waste liquid recovery process produced by the reaction of 1,2-dibromo-3,3,3-trifluoropropane and sodium hydroxide, and extracts and recovers bromine and sodium hydroxide.

2. The process for recovering sodium bromide waste liquid in the production process of 2-bromo-3,3,3-trifluoropropene according to claim 1, characterized in that: The extraction and collection routes of bromine include acidification, ion exchange, electrolysis, displacement, evaporation, adsorption purification, and condensation.

3. The process for recovering sodium bromide waste liquid in the production process of 2-bromo-3,3,3-trifluoropropene according to claim 1, characterized in that: The recovery route of sodium hydroxide includes liquid-liquid separation, electrolysis, and evaporative crystallization.

4. The sodium bromide waste liquid recovery device in the production process of 2-bromo-3,3,3-trifluoropropene according to claim 1, characterized in that: The hydrochloric acid storage tank is connected to a metering pump to control the rate and amount of hydrochloric acid added to the acidification tank; in the ion exchange chamber, the chloride ions in the acidification solution are separated by ion exchange resin and collected in the chloride ion enrichment chamber; the electrolysis chamber is divided into an anode area and a cathode area, and a chlorine separator is installed in the anode area to collect the chlorine generated by electrolysis and enter the chlorine storage tank for storage, and a hydrogen separator is installed in the cathode area to collect the hydrogen generated by electrolysis, and the hydrogen is purified and stored in the hydrogen storage tank. The ion exchange chamber uses ion exchange resin to separate bromide ions from sodium ions, and the separated bromide ion solution enters the bromide ion enrichment chamber to undergo a replacement reaction with chlorine; the bromine element obtained by replacement is further separated from the sodium ion and chloride ion solution by a liquid-liquid separator, and the bromine gas after the bromine element is vaporized in the evaporator enters the adsorption tower for purification, and is finally sent to the condenser to condense into liquid bromine.

5. A sodium bromide waste liquid recovery device in the production process of 2-bromo-3,3,3-trifluoropropene, characterized in that: The bromine extraction and collection device includes an acidification tank, a hydrochloric acid storage tank, a metering pump, an ion exchange chamber, an electrolysis chamber, an ion exchange chamber, a bromide ion enrichment chamber, an evaporator, an adsorption tower, and a condenser.

6. The sodium bromide waste liquid recovery device in the production process of 2-bromo-3,3,3-trifluoropropene according to claim 5, characterized in that: The recovery route of sodium hydroxide includes liquid-liquid separation, electrolysis, and evaporative crystallization.

7. The sodium bromide waste liquid recovery device in the production process of 2-bromo-3,3,3-trifluoropropene according to claim 5, characterized in that: The sodium hydroxide recovery device includes a liquid-liquid separator, a sodium ion enrichment chamber, an electrolysis chamber, and an evaporator. The liquid-liquid separator separates the layered bromine element from the sodium ion and chloride ion solutions. The separated sodium ion solution enters the sodium ion enrichment chamber, where the sodium ion solution is electrolyzed. The electrolyzed solution is sent to the evaporator for evaporation and crystallization, and the obtained sodium hydroxide solid enters the sodium hydroxide storage chamber for collection.

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