JPH0556329B2

JPH0556329B2 -

Info

Publication number: JPH0556329B2
Application number: JP59504439A
Authority: JP
Inventors: Richaado Shii Deitsukaason; Uiriamu Esu Miraa
Original assignee: EKOROKEMU Inc
Current assignee: EKOROKEMU Inc
Priority date: 1983-11-30
Filing date: 1984-11-27
Publication date: 1993-08-19
Also published as: JPS61500553A

Description

[Brief explanation of the drawing]

第１図はサービスサイクルにおける、本発明の
装置および方法を示すフローチヤートであり、第
２図は再生サイクルにおける、本発明の装置およ
び方法を示すフローチヤートである。１１，１４，１７，２０…導管、１２…濾過
器、１３…濾過媒体、１５…ベツド、１６…陽イ
オン交換樹脂、１８…ベツド、１９…陰イオン交
換樹脂、２１…仕上げ器、２２…混合−ベツド樹
脂。 FIG. 1 is a flowchart illustrating the apparatus and method of the present invention during a service cycle, and FIG. 2 is a flowchart illustrating the apparatus and method of the present invention during a regeneration cycle. 11, 14, 17, 20... Conduit, 12... Filter, 13... Filtration medium, 15... Bed, 16... Cation exchange resin, 18... Bed, 19... Anion exchange resin, 21... Finisher, 22... Mixing - bed resin.

Claims

[Scope of Claims] 1. A method for treating wash water from a terephthalic acid production process when the wash water contains dissolved terephthalic acid, a metal catalyst, and a dissolved organic acid byproduct, the method comprising: A terephthalic acid manufacturing process comprising a first step of passing the wash water through a cation exchange resin and a second step of passing the wash water through an anion exchange resin to remove the terephthalic acid and the dissolved organic acid by-products. How to treat washing water. 2. The washing water further contains insoluble solids consisting of at least terephthalic acid or organic acid by-products, and the washing water is carried out prior to the first step in order to precipitate the insoluble solids onto the filtration medium. 2. The method of claim 1, further comprising the step of filtering the water. 3. The method of claim 1, further comprising the step of passing said wash water through a mixed bed resin after said second step. 4. The method of claim 1, wherein the organic acid by-products consist of p-toluic acid and benzoic acid. 5. The method of claim 1, wherein the metal catalyst is selected from the group consisting of cobalt, manganese, or mixtures thereof. 6. The method according to claim 1, wherein the anion exchange resin is a weakly basic anion exchange resin or an intermediately basic anion exchange resin. 7. The method according to claim 1, wherein the cation exchange resin is a strongly acidic cation exchange resin. 8. The method according to claim 1, further comprising a step of recycling the wash water to the terephthalic acid production step after the second step. 9. The method according to claim 1, further comprising a step of regenerating the cation exchange resin by removing the metal catalyst from the cation exchange resin after treating a certain amount of washing water. Method. 10 A patent characterized in that the regeneration step comprises a step of bringing the cation exchange resin into contact with an acid capable of displacing the metal catalyst from the cation exchange resin without damaging the cation exchange resin. The method according to claim 9. 11. The method according to claim 10, wherein the displaceable acid is a strong mineral acid. 12. A patent characterized in that the displaceable acid is hydrobromic acid, and the method includes recycling the hydrobromic acid to the terephthalic acid production process after at least one cycle of the regeneration step. The method according to claim 11. 13. The method according to claim 9, further comprising a step of recycling the metal catalyst to the terephthalic acid production step after the regeneration step. 14. Claim 1, comprising a step of regenerating the anion exchange resin by removing the terephthalic acid and the by-products from the anion exchange resin after treating a certain amount of wash water. The method described in section. 15. The regeneration step comprises contacting the anion exchange resin with an acid capable of displacing the terephthalic acid and by-products from the anion exchange resin without damaging the resin. A method according to claim 14. 16. said displaceable acid is a weak acid selected from the group consisting of glacial acetic acid and formic acid, and said method comprises removing said weak acid from said anion exchange resin after contacting said weak acid with said anion exchange resin. 16. The method of claim 15, further comprising the step of removing. 17. The displaceable acid is glacial acetic acid, and the method includes recycling the glacial acetic acid to the terephthalic acid production step after the regeneration step. the method of. 18. Removal of the displaceable acid by contacting the anion exchange resin with an alkali capable of displacing the weak acid from the anion exchange resin without damaging the anion exchange resin. 16. The method of claim 15, comprising: 19. The method of claim 18, wherein the alkali is selected from the group consisting of ammonia, sodium carbonate, potassium hydroxide and sodium hydroxide. 20. The method of claim 2, further comprising the step of backwashing the filtration medium to remove insoluble organic acid solids precipitated on the filtration medium. 21. The method of claim 1, wherein the step of producing terephthalic acid comprises a step of liquid phase air oxidation of p-xylene. 22 When the washing water from the terephthalic acid production step further contains insoluble terephthalic acid and insoluble organic acid byproducts, the first step is for removing the metal catalyst, the insoluble terephthalic acid, and the insoluble organic acid byproducts. passing the wash water through a cation exchange resin, wherein the second step is passing the wash water through an anion exchange resin to remove the dissolved terephthalic acid and dissolved organic acid byproducts. A method according to claim 1, characterized in that: 23 A washing water treatment device in the case where the washing water from a terephthalic acid manufacturing process contains dissolved terephthalic acid, a metal catalyst, and a dissolved organic acid by-product, which comprises a first bed filled with a cation exchange resin, and an anion exchange resin. a second bed filled with exchange resin;
An apparatus for treating wash water from a terephthalic acid manufacturing process, comprising a connecting conduit for passing the wash water through the first bed and then through the second bed. 24 a filtration medium through which the wash water passes before passing through the first bed, the wash water further containing insoluble terephthalic acid solids and insoluble organic acid byproduct solids; 24. Apparatus according to claim 23, characterized in that the method includes the step of filtering the wash water to remove the solids. 25. The apparatus of claim 23, further comprising a conduit for passing regeneration acid through the cation exchange resin bed to regenerate the cation exchange resin. 26. The apparatus of claim 23, further comprising conduits for passing weak acids and alkalis through the anion exchange resin bed to regenerate the anion exchange resin. 27. The apparatus of claim 24, further comprising a conduit for flowing backwash water through a filter for solids removal. FIELD OF INDUSTRIAL APPLICATION This invention relates to the recovery and recycling of organic acids, water and other beneficial components in wash water generated during the production of terephthalic acid. [Prior Art and Problems] Terephthalic acid of industrial purity is mainly produced by liquid phase air oxidation of p-xylene. A typical method involves continuously feeding a solvent, air, and catalyst into a reactor to oxidize at high temperature. Acetic acid is used as a solvent, polyvalent metals such as cobalt and manganese are used as catalysts, and bromine is used as a renewable free radical source. The terephthalic acid remains in the reactor as a slurry, and the slurry is passed through a surge tank operated at a lower temperature and pressure than the reactor, and then the terephthalic acid crystals are recovered by centrifugation, washing, and drying. A typical method for producing terephthalic acid by liquid-phase air oxidation of p-xylene is described in Kirk-Othemer's Encyclopedia of Chemical Technology.
Technology), Vol. 17 (1982), p. 749. Other methods use similar steps and materials. The cleaning solution for cleaning terephthalic acid crystals contains uncrystallized terephthalic acid, by-products such as p-toluic acid and benzoic acid, and catalysts from the terephthalic acid crystals. Terephthalic acid production equipment generates a large amount of such washing water, and environmental standards prohibit discharging untreated wastewater into natural water systems. Conventionally, this wash water is left in a biological treatment pool for a long period of time to remove certain environmentally harmful components by converting them into harmless components by microorganisms. Not only was this process uneconomical and time consuming, but recirculation of the wash water was not possible because compound biological treatment pools do not remove all components contained in the wash water. Importantly, conventional wash water treatment methods did not recover or reuse any of the components in the wash water. Upon removal of components in the biological treatment pool, the components were either degraded by microorganisms or settled to the bottom of the treatment pool as unusable sludge. Accordingly, it would be desirable to provide an improved method for treating wash water generated during the production of terephthalic acid. The improved process must be such that the components can be recovered from the wash water and the water can be released into the natural system or further recycled for the production of terephthalic acid. Preferably, the method is one in which useful components in the wash water can be recovered and the recovered components can be reused for the next production of terephthalic acid. Particularly preferred methods are such that the method can be carried out in one unit and the material used for regeneration can also be recovered and reused for the production of terephthalic acid. Such improved methods should be efficient, economical, and do not require the large amount of land required for conventional biological treatment pools. These objectives can be achieved by the method of the invention. Other objects of the invention will become clearer from the following recollection. [Means for Solving the Problems] The present invention relates to a method for treating washing water generated during the production of terephthalic acid, and the washing water at this time contains terephthalic acid, a metal catalyst, and an organic acid byproduct. . This method involves passing wash water through a filtration medium to remove undissolved terephthalic acid solids, passing the filtrate through a proton-type cation exchange resin to remove metal catalyst, and passing the filtrate through a layer of anion exchange resin to dissolve it. A step of removing terephthalic acid and dissolved organic acid byproducts is included. Certain components recovered from the wash water and the treated water are further recycled for the production of terephthalic acid. A device for carrying out this method is also encompassed by the invention, but after treating a certain amount of wash water, the device is regenerated with a regenerant, which is also recovered for further production of terephthalic acid. reused for purposes. The apparatus for treating washing water generated during the production of terephthalic acid according to the present invention is shown in Figures 1 and 2 of the attached drawings.
It is outlined in the figure. FIG. 1 shows a service cycle, and FIG. 2 shows a regeneration cycle. This washing water is generated from the washing process during the production of terephthalic acid, and contains uncrystallized terephthalic acid, metal catalyst,
and undesirable organic acid by-products carried from the terephthalic acid crystals. Although the method of the present invention can advantageously carry out the treatment of wash water during the production of terephthalic acid as described above, it can also be used to treat other terephthalic acids containing organic acids and catalyst components similar to those described in the present invention. It can also be applied to washing water. The reaction that produces terephthalic acid uses metal catalysts, including polyvalent metals such as cobalt and manganese. The organic acid by-products include p-toluic acid, benzoic acid and other organic acid by-products. The temperature of the washing water generated during terephthalic acid production is initially as high as approximately 148°C. Since the processing apparatus of the present invention is filled with ion exchange resin, the resin deteriorates and loses its capacity at high temperatures such as 148°C. Therefore, the wash water is cooled before being introduced into the apparatus to a level that does not damage the resin. about 64
℃ is sufficient, but if a resin that can be treated at high temperatures is used, higher temperatures can be used. On the other hand, it is best not to cool the water below about 0° C. before introducing it into the device, as low temperatures will inhibit the flow of water through the system. As shown in FIG. 1, the wash water is passed through conduit 11 and filter 12. The filter media 12 is selected to be capable of depositing all of the undissolved organic solids in the wash water thereon. Suitable filtration media include filter sand, anthracite, garnet, etc., with particle sizes selected to cause precipitation of insoluble organic solids. Sand having a particle size of 0.3 to 1.0 mm is the preferred filtration media. In a preferred embodiment,
Filtration sand with a particle size of 0.45 mm or approximately 40 mesh was used. Following filtration, the wash water is passed through conduit 14 and the cation exchange resin bed (sometimes referred to as the bed).
Pass it through. This bed is filled with a hydrogen ion type cation exchange resin, which has the function of removing all catalysts such as cobalt and manganese, and prevents contamination of the downstream anion exchange resin. Although any commercially available strong acid type or weak acid type cation exchange resin can be used, a strong acid type cation exchange resin is preferred. Hydrogen ion type strong acid type cation exchange resin “Ionac C250” (product name) (manufactured by Sybron Corp.)
was used in the embodiment. After removing the metal catalyst from the wash water, it is transferred to conduit 17.
It is introduced into the anion exchange resin bed 18 via the anion exchange resin layer bed 18. The anion exchange resin packed into the bed removes substantially all of the dissolved organic acid byproducts. Dissolved organic acids include p-toluic acid, benzoic acid, and any terephthalic acid not removed by filter media 13. For this purpose, commercially available strongly basic, weakly basic or intermediately basic inion exchange resins can be used, with intermediately basic anion exchange resins being preferred. An example of an intermediate basic anion exchange resin is the product name "Ionac-365".
(manufactured by Sybbron Corp.). By removing the catalyst before passing the wash water through the anion exchange resin layer, contamination of the anion exchange resin is reduced. Alternatively, there is a method in which the filtration step is omitted and the insoluble organic acid solid content is recovered on the cation exchange resin, but this is not recommended because the capacity of the cation exchange resin is reduced due to contamination with the insoluble organic acid. After removing the organic acids, the wash water is optionally passed through a conduit 20 and a polisher 21, which is filled with a mixed-bed resin 22. The mixed-bed resins are composed of commercially available strong acid type cation exchange resins and strong base type anion exchange resins, and the types thereof are not limited. In a preferred embodiment, Inac C-249 cation exchange resin and Ionac ASB-1 anion exchange resin were used. The wash water treated during the above service cycle passes environmental standards and can be released as is. However, it is more advantageous to reuse this water as wash water for the subsequent production of terephthalic acid. In the present invention, there is no need for a biological treatment pool, and the treated wash water is repeatedly reused. This not only reduces disposal costs, but also the cost of providing wash water of adequate purity. After processing a certain amount of wash water, a regeneration cycle is turned on for regeneration of the filtration media and ion exchange resin to recover the useful components removed from the wash water. This regeneration cycle is shown in FIG. During this regeneration cycle, conduit 23, filter 1
2, and backwash the filtration media 13 by passing backwash water through conduit 24 to reverse the direction of flow through the filtration media from that during the service cycle. By this backwashing, insoluble organic acid solids collected from the wash water are removed from the filter, and the solids are recovered from the wash water by a decantation method. In this way, terephthalic acid, which conventionally escaped in the waste water, can be added to the overall yield of the manufacturing process. After decantation,
This backwash water is discharged or preferably subjected to recirculation. The step of regenerating the cation exchange resin includes the step of removing the metal catalyst from the resin. This process is
The resin is brought into contact with an acid capable of displacing metal ions from the resin without damaging the resin. Any type of regenerating acid selected from the group consisting of strong acids does not matter, but hydrobromic acid or hydrochloric acid is preferred. Hydrobromic acid diluted from 2 to 48% is very effective in regenerating cation exchange resins and can be recycled to the terephthalic acid production process at the same time. After being used in one regeneration cycle, the hydrobromic acid is either recycled directly to the terephthalic acid manufacturing process or is first reused in the next regeneration cycle before being recycled. The regeneration step is performed by passing regenerated acid through conduit 25, cationic resin 16, and conduit 26. During this regeneration process, the cation exchange resin releases metal catalysts, which are either discarded or recycled for subsequent terephthalic acid production. Regeneration of the anion exchange resin involves removing terephthalic acid and byproducts from the resin. This removal step is accomplished by first passing through conduit 27, anion exchange resin 19, and conduit 28 a weak acid capable of displacing terephthalic acid and byproducts without damaging the resin. Glacial acetic acid and formic acid are suitable for this purpose, the former being preferred because it can be recycled to the terephthalic acid manufacturing process which uses acetic acid as the solvent in the air oxidation of p-xylene to terephthalic acid. This weak acid will leach out any dissolved p-toluic acid, benzoic acid, and terephthalic acid that precipitated on the anionic resin during the service cycle. An alkali capable of displacing the weak acid from the resin without damaging the resin, such as ammonia, sodium carbonate, potassium hydroxide, or sodium hydroxide, is then passed through conduit 29, anionic resin 19, and conduit 30 to the resin. Remove any weak acids trapped inside. In a preferred embodiment, 5-10% diluted sodium hydroxide is used, and the effluent consisting of sodium acetate and excess sodium hydroxide is treated for disposal or reuse. In one embodiment, this effluent is reused in the next regeneration cycle for weak acid removal. Following the regeneration cycle, the device is again ready for use for the next wash water treatment. The apparatus of the invention consists of ion exchange resin and filter tanks, valves, conduits, and auxiliary equipment suitable for receiving resin and filtration media. Such a system is disclosed in US Pat. No. 4,383,920, which is incorporated herein by reference. Modifications to such systems will be within the skill of those skilled in the art to accommodate the needs of the present invention. In particular, when using hydrobromic acid for certain types of tanks, rubber linings may prove to be unsuitable, in which case another suitable lining may be selected. It will become necessary. Although specific embodiments have been described above, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope and spirit of the invention.