JP2010527785A - Method for recovering oxidation catalyst using ion exchange resin - Google Patents

Abstract

  A method for the removal and recovery of at least one heavy metal and at least one halogen from a liquid stream in a chemical process is disclosed. The method includes contacting the liquid stream with a strongly basic anion exchange resin and contacting the effluent stream from the first step with a chelating cation exchange resin. This recovery method optionally includes the step of regenerating the anion exchange resin by contacting the anion exchange resin with an anion exchange resin regeneration solution to form the recovered heavy metal and halogen. Optimally, the recovery method of the present invention also includes the step of regenerating the chelated cation exchange resin to form recovered heavy metals and halogens.

Description

Cross Reference to Related Patent Applications This patent application claims the benefit of US Provisional Patent Application No. 60 / 932,400, filed May 31, 2007.
The present invention relates to a heavy metal and halogen recovery process using a series of ion exchange resins and chelating resins.

  The production of aromatic carboxylic acids often occurs by means of direct oxidation of aromatic hydrocarbons. Among these, terephthalic acid is one such carboxylic acid used in the manufacture of many different polymers, including polyethylene terephthalate (PET). Terephthalic acid is produced by the direct oxidation of p-xylene catalyzed by heavy metals such as Co and Mn and radical initiators such as bromine. This oxidation product is subsequently crystallized and subjected to i) a solid stream containing the product, ii) a mother liquor stream that is partially recycled to the oxidation process, and iii) a solid-liquid separation that produces a liquid stream. . This liquid stream is treated for solvent recovery, in which the catalyst and radical initiator present in the liquid stream is lost or of low efficiency chemical and / or physical processes. Only partially recovered by means. Further, when low purity feedstock is used for the production of aromatic carboxylic acids, the liquid stream is increased relative to other streams, increasing the value of catalyst and initiator lost by the liquid stream. Must-have.

  Recent efforts have been attempted to address the loss of catalyst during the production of aromatic carboxylic acids. For example, Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4 and Patent Literature 5 all describe various methods for recovering catalyst components, such as heavy metals and / or halogens. However, the above prior art documents require the use of methods and / or expensive capital equipment that require one or more pretreatments of the streams involved in the method of recovering heavy metals or halogens. Methods are described that require extra processing steps to perform.

  Other efforts for heavy metal and halogen recovery described include the use of ion exchange resins. For example, Patent Document 6, Patent Document 7 and Patent Document 8 describe a method for recovering heavy metal ions and / or halogens by using an ion exchange resin. However, these documents require expensive pretreatment steps or other processing steps that require expensive capital equipment.

  Recovering and purifying larger amounts of heavy metals and halogens in a more efficient way that does not require extra processing steps or pretreatment of streams containing heavy metals and halogens has become a technology in the recovery of heavy metals and halogens. It would be an advantage. It would also be an advantage in the technical field of heavy metal and halogen recovery to utilize ion exchange resins in a means to optimize heavy metal and halogen recovery.

US Patent Application Publication No. 2002 / 0016500A1 US Pat. No. 3,959,449 US Pat. No. 4,202,797 US Pat. No. 4,162,991 Japanese Patent Application Laid-Open No. 10-15390A U.S. Pat. No. 4,238,294 US Pat. No. 5,880,313 US Pat. No. 5,955,394

  In a first aspect, the present invention is a method for the removal and recovery of at least one heavy metal and at least one halogen from a liquid stream in a chemical process comprising: a) And b) contacting the effluent stream from step (a) with the chelating cation exchange resin. This recovery method optionally includes the step of regenerating the anion exchange resin by contacting the anion exchange resin with an anion exchange resin regeneration solution to form the recovered heavy metal and halogen. Optimally, the recovery method of the present invention also includes the step of regenerating the chelated cation exchange resin to form recovered heavy metals and halogens.

  In a second aspect, the present invention removes and recovers from a liquid stream in a chemical process i) at least one heavy metal selected from the group consisting of Co, Mn and combinations thereof and ii) bromine. A) contacting the liquid stream with a strongly basic anion exchange resin in halide form, b) contacting the effluent from step (a) with a chelating cation exchange resin, c ) Contacting the anion exchange resin with an anion exchange resin regeneration solution containing water and acetic acid to regenerate the anion exchange resin in step (a) to form recovered heavy metals and bromine; d) The chelating cation exchange resin is contacted with a regeneration primer containing HBr, and then the chelating cation exchange resin is contacted with a regeneration solution containing water. Regenerating the chelated cation exchange resin to form recovered heavy metal and bromine, and e) contacting the recovered heavy metal and bromine with a strongly basic anion exchange resin in hydroxide form, Purifying the recovered heavy metal and bromine to form purified heavy metal and bromine, and f) removal comprising using the purified heavy metal and bromine in the chemical process And a recovery method.

  The present invention provides a method for the recovery of metals and halogens that does not require pretreatment or extra processing steps of the liquid stream.

FIG. 1 is a flow diagram of one embodiment of the recovery system of the present invention. FIG. 2 is a flow diagram of another embodiment of the recovery system of the present invention.

  The present invention is a method for recovering a catalyst used in a chemical process. In one aspect, the chemical process includes, but is not limited to, an alkyl aromatic liquid, including di- and trimethylbenzene, that produces one or more catalyst-containing liquid streams. Phase oxidation process. In one embodiment, the liquid stream (s) are removed from the oxidation process and then separated into a solid-containing product stream, a mother liquor stream and a liquid stream, where the liquid stream comprises a catalyst, a reaction solvent, Reaction intermediates, reaction by-products and corrosion products). Examples of liquid phase oxidation processes include the production of terephthalic acid, isophthalic acid and trimellitic acid. The production of terephthalic acid includes, for example, the oxidation of p-xylene to produce terephthalic acid. Catalysts used for liquid phase oxidation and ending in a liquid stream contain heavy metals and / or halogens. In many embodiments, such as terephthalic acid, isophthalic acid, and trimellitic acid processes, the heavy metal includes one or more of cobalt, manganese, cerium, zirconium and hafnium, and the halogen includes bromine.

  FIG. 1 shows one embodiment of a recovery system 10 that can be used for the present invention. As shown, the recovery system 10 includes a reservoir 11, a column 13 containing an ion exchange resin, and a bed 17 containing a chelating resin.

  As shown in FIG. 1, the liquid stream 12 is removed from the reservoir 11. The shape of the reservoir 11 is not critical to the present invention, and as in most chemical processing systems, the characteristics of the chemical process will determine the shape and structural materials of the reservoir 11 and other auxiliary devices.

  The concentration of heavy metals and halogens in the liquid stream 12 is not critical to the present invention, and the present invention is effective at almost all concentrations of heavy metals and / or halogens. Typical concentration ranges of heavy metals and halogens in the liquid stream may be, for example, 200 to 1000 parts / million (ppm) bromide concentration, 100 ppm to 800 ppm cobalt concentration, and 200 ppm to 1000 ppm manganese concentration.

  This liquid stream is supplied from the reservoir 11 to the ion exchange resin bed 13 where the liquid stream is in contact with at least one ion exchange resin as it passes through the ion exchange resin bed 13. Optimally, the temperature of the liquid stream 12 when in contact with the ion exchange resin is in the range of 20 to 150 ° C, more preferably 40 to 100 ° C, and most preferably 65 to 100 ° C.

  The ion exchange resin is a strongly basic anion exchange resin selected to absorb at least a portion of heavy metals and halogens from the liquid stream. Preferably, the strongly basic anion exchange resin is a strongly basic anion exchange resin in the halide form, more preferably a chlorinated or brominated anion exchange resin. Preferably the strongly basic anion exchange functional group is an amine group. Most preferably, the strongly basic anion exchange resin is a strongly basic quaternary amine anion exchange resin in bromide form. For anion exchange resins in bromide form, as is known in the art, conversion of a strongly basic anion exchange resin to bromide form involves the conversion of a resin bed in any form into a resin bed volume ( Washed with 10-50 times stronger base solution (defined as the volume of ion exchange resin bed in the specification) and then bromide at a concentration of 5-20 resin bed volume, preferably at least 3% by weight bromide. It can be obtained by washing with a solution containing

  This strongly basic anion exchange resin can be supported on any matrix. Preferably the strongly basic anion exchange resin is supported on a styrenic matrix, more preferably a styrene-divinylbenzene matrix.

  The direction of flow of the liquid flow through the resin bed 13 is not critical. However, as shown in FIG. 1, typically a liquid stream will be fed to the top of the resin bed 13 such that it flows down through the resin bed 13.

  The effluent stream 16 from the column 13 contains the reaction solvent, residual catalyst, reaction byproducts, reaction intermediates and corrosion products that have not been absorbed by the strongly basic anion exchange resin. The exhaust stream 16 is fed to the bed 17 where it comes into contact with the chelating resin. This chelating resin absorbs the remaining heavy metals and / or halogens so that the resulting effluent stream 18 is substantially free of heavy metal catalysts and / or halogens. Thus, the effluent stream 18 consists essentially of reaction by-products, reaction intermediates, and corrosion products.

  The chelating resin in the bed 17 is a resin selected to absorb heavy metals and / or halogens, more specifically cobalt, manganese, cerium, zirconium, hafnium, bromine from the liquid stream. Preferably the chelating group of the chelating resin is a carboxylic acid chelating group, more preferably a dicarboxylic acid group. Most preferably the chelating resin is an imidodiacetic acid resin. The chelating resin may be in any form, such as sodium or hydrogen form, more preferably in hydrogen form.

  The chelating resin can be supported on any matrix. Preferably the chelating resin is supported on a styrenic matrix, more preferably a styrene-divinylbenzene matrix.

  The direction of flow of the exhaust stream 16 through the chelating resin bed 17 is not critical. However, as shown in FIG. 1, typically, the exhaust stream 16 will be fed to the top of the bed 17 so that it flows down through the bed 17.

  After a certain time, like most ion exchange resins and chelating resins, the anion exchange resin in the column 13 and the chelating resin in the bed 17 become completely filled with heavy metals and / or halogens and are therefore regenerated. Must. A person skilled in the art will typically have a resin bed that is sized to last a specific time before regeneration is required, or has heavy metal and / or halogen concentration levels in the effluent stream 18. Understand that it changes and informs the need for regeneration. During the regeneration process, heavy metals and / or halogens are recovered and optimally can be used in the production process for aromatic carboxylic acids.

  In order to regenerate the anion exchange resin, the anion exchange resin is brought into contact with an anion exchange resin regeneration solution. Preferably the anion exchange resin regeneration solution comprises water or a combination of water and acetic acid. Preferably, the concentration of water in the anion exchange resin regeneration solution is 10 to 100% by weight, more preferably 30 to 70% by weight. Preferably, the concentration of acetic acid in the anion exchange resin regeneration solution is 90 to 0% by weight, more preferably 70 to 30% by weight.

  To regenerate the chelated resin, the chelated resin is first contacted with a regeneration primer and then contacted with a chelated cation exchange resin regeneration solution.

  The regeneration primer contains an acid, such as hydrochloric acid or hydrobromic acid, and may contain acetic acid. The concentration of hydrobromic acid or hydrochloric acid in the regeneration primer is preferably 1 to 20% by weight, more preferably 2 to 10% by weight, and still more preferably 3 to 6% by weight. The concentration of acetic acid in the regeneration primer is preferably 0 to 98% by weight, more preferably 10 to 95% by weight, and still more preferably 85 to 90% by weight. Optionally, water can be added to the regenerated primer at a preferred concentration of 1.5-100% by weight, more preferably 3-50% by weight, and even more preferably 4-35% by weight. The volume of regeneration primer used is selected so that 3-10 g bromide is fed to the resin for every gram of metal absorbed. During this process, some of the heavy metal is recovered along with the bromide absorption by the resin. For example, when cobalt and manganese are heavy metals, 10% or less of the cobalt charged to the chelating resin and 50% or less of manganese can be recovered from the chelating resin during this step.

  The chelated cation exchange resin regeneration solution preferably comprises water or a combination of water and acetic acid. The concentration of water in the chelated cation exchange resin regeneration solution is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, still more preferably 80 to 100% by weight. The concentration of acetic acid in it is 0-30% by weight. The resulting stream contains recovered heavy metals and halogens in a halide to heavy metal ratio of about 3 to about 10. In the PTA process, for example, the ratio of Br −: (Co + Mn) is about 2 to about 10, more preferably 2 to 8, and even more preferably 2 to 5. This stream containing the recovered heavy metal and halogen is then purified as follows.

  Referring to FIG. 2, an alternative recovery system 20 is also possible. The recovery system 20 in FIG. 2 includes a reservoir 21 and a chelating resin bed 23. As shown, the chelating resin is selected such that only a chelating resin is required and no anion exchange resin is required to recover heavy metals and halogens. In other respects, the floor 23 operates in the same manner as the floor 17 in the embodiment shown in FIG. The discharge stream 24 has characteristics similar to those of the discharge stream 18 in the embodiment shown in FIG.

  Optimally, the recovered heavy metals and / or halogens are purified before being used in the aromatic carboxylic acid process. Such purification steps include contacting the recovered heavy metal and halogen with a strongly basic anion exchange resin. The strongly basic anion exchange resin used for purification is preferably in the hydroxide or acetate form, and more preferably in the hydroxide form.

  As shown in FIG. 1, the feed stream 19 contains recovered heavy metals and halogens to be purified. In the embodiment shown in FIG. 2, the feed stream 25 contains recovered heavy metals and halogens to be purified. Feed stream 19 or feed stream 25 is fed to a bed 40 containing a strongly basic anion exchange resin used for purification. Feed stream 19 or feed stream 25 can be fed to bed 40 in series with a strongly basic anion exchange resin bed and chelating cation exchange resin bed 17/23 or by means of a buffer vessel 30 fitted with a pump. . The feed stream 19 or the feed stream 25 is optimally at least so as to optimize the efficiency of the operation of the strongly basic anion exchange resin 40 in the purification stage and as shown in FIG. Contains 35% water. After the purification step, stream 41 containing the purified heavy metal and halogen can be fed back into the oxidation process.

  When the strongly basic anion exchange resin in bed 40 is completely filled with bromide, it must be regenerated. A person skilled in the art will typically have a resin bed that is sized to last a specific time before regeneration is required, or the concentration level of heavy metals and / or halogens in the outlet stream varies. And understand the need for regeneration. As shown in FIG. 2, regeneration of this strong base anion exchange resin in the bed 40 is performed by washing with a hot strong base solution 42, for example, a regenerant that is a NaOH solution or a KOH solution. The resulting solution from outlet 43 is sent for proper disposal or recycling.

As used in the examples, the defined term “DOWEX 21K-XLT” means a strongly basic anion exchange resin in chloride form, manufactured by The Dow Chemical Company. To do.

  “DOWEX IDA-1” means a chelated cation exchange resin manufactured by The Dow Chemical Company.

  “Tower A” means a jacketed glass tower packed with 250 mL of DOWEX 21K-XLT.

  “Tower B” means a jacketed glass tower packed with 250 mL of DOWEX 21K-XLT.

  “Tower C” means a jacketed glass tower filled with 390 mL of DOWEX IDA-1.

  “Feed” means the liquid stream from the PTA process to be treated according to the present invention.

  “Exhaust” means the discharge stream from column A, B or C.

  "Eluted catalyst" means a catalyst regenerated from column A, B or C according to the present invention.

Procedure used in the examples Procedure for converting the anion exchange resin to the bromide form DOWEX 21K-XLT was converted to the bromide form as follows. 12 liters of NaOH 4 wt% aqueous solution was passed through the resin bed in the tower A while circulating water at 70 ° C. in the tower jacket. Water was then passed through the resin bed to a neutral pH on the discharge side, and then the resin bed was washed with 1000 mL of a 4 wt% aqueous solution of HBr.

Procedure for converting anion exchange resin to OH form DOWEX 21K-XLT in column B was converted to OH form as follows. 12 liters of NaOH 4% by weight aqueous solution was passed through the resin bed in tower B while circulating water at 70 ° C. in the tower jacket. Water was then passed through the resin bed to a neutral pH on the discharge side.

Procedure for Determining Metal Ion Concentration The metal ion concentration was determined using an atomic absorption spectrophotometer analysis 300 by Perkin Elmer. Samples to be analyzed were appropriately diluted with water and absorbance values were measured using the following operating conditions.

  The absorbance value of the sample was compared to the absorbance of a standard for atomic absorption spectrometry in a Normex vial containing the solution at a concentration certified by the manufacturer. The concentration in mg / L of each single metal is automatically calculated by the instrument control software.

Procedure for Measuring Bromide Concentration Bromide was measured by titration with silver nitrate (AgNO ₃ ) according to the following procedure.

  Weigh about 30 g of sample.

  Add 5 mL of ammonium iron sulfate solution and 5 mL of 1: 1 nitric acid into the flask. The final color of the solution is yellowish green.

Add 2-3 drops of 0.02N ammonium thiocyanate (NH ₄ CNS) solution. This solution will turn orange-red.

Add 0.02N AgNO ₃ in excess to the point where the orange-red color disappears.

Excess AgNO ₃ is titrated with NH ₄ CNS until a new orange-red color appears.

The bromide concentration was calculated using the formula: Br = (A−B) × N × 79.9 × 100 / P × 1000 (where
A = mL of AgNO ₃ consumed;
B = mL of NH ₄ CNS consumed;
N = normality of solution for titration (0.02N) and P = sample weight)
To do.

Example 1
Tower A and Tower C are placed in series similar to the shape shown in FIG. Here, the resin bed 13 is the tower A, and the resin bed 17 is the tower C. The feed stream to column A contains heavy metals and halogens, reaction solvents, oxidation reaction byproducts, oxidation reaction intermediates and corrosion products at the specific concentrations reported in Table I. This feed stream is heated to 70 ° C. 500 mL of glacial acetic acid is pumped through the two resin beds, then the stream to be tested is fed to the resin bed and collected at the discharge side of the last bed. The tower jacket temperature is kept constant during the test. After absorption, the tested stream is removed from the tower by pumping glacial acetic acid through the two beds. The regeneration is 100% water as the regenerant for column A, 100% water as the regeneration solution for column C and a solution composed of acetic acid / HBr / water = 90/4/6 wt% as the primer for column C Performed using a solution of% water. At the end of the test, the two resin beds were washed with glacial acetic acid. Relevant data is reported in Table I.

Example 2
The arrangement is similar to that shown in FIG. 2 where the procedure used in Example 1 is repeated except that column C is the resin bed 23 and only column C is tested. The regeneration was carried out using a solution composed of acetic acid / HBr / water = 90/4/6 wt% as a primer for column C and a solution of 100% water as the regeneration solution for column C. Relevant data is reported in Table I.

Example 3
The arrangement is similar to that shown in FIGS. 1 and 2, where tower B is tested such that tower B is resin bed 40. The feed stream composition representing the composition of streams 19 and 25 in FIGS. 1 and 2, respectively, is reported in Table I. 500 mL of glacial acetic acid is pumped through the resin bed and then the stream to be tested is fed to the resin bed and collected at the discharge side of the bed itself. The tower jacket temperature is kept constant during the test. After absorption, the tested stream is removed from the tower by pumping water through the bed. Relevant data is reported in Table I.

Example 4
The same procedure performed in Example 3 is repeated except that the water concentration of the feed stream is increased to 35% by weight. Relevant data is reported in Table I.

Claims (21)

A method for removing and recovering at least one heavy metal and at least one halogen from a liquid stream in a chemical process comprising:
a) contacting said liquid stream with a strongly basic anion exchange resin, and b) contacting the effluent from step (a) with a chelating cation exchange resin. The method of claim 1, further comprising the step of c) regenerating the anion exchange resin by contacting the anion exchange resin with an anion exchange resin regeneration solution to form recovered heavy metals and halogens.   The method of claim 2, wherein the anion exchange resin regeneration solution comprises water and acetic acid. The method according to any one of claims 1 to 3, further comprising the step of d) regenerating the chelated cation exchange resin to form recovered heavy metals and halogens.   5. The method of claim 4, wherein step (d) comprises contacting the chelated cation exchange resin with a regenerating primer and then contacting the chelated cation exchange resin with a chelated cation exchange resin regeneration solution.   The method of claim 5, wherein the regeneration primer comprises hydrogen bromide or hydrogen chloride.   The method according to claim 5 or 6, wherein the chelated cation exchange resin regeneration solution is water. The method according to any one of claims 1 to 7, further comprising the step of e) purifying the recovered heavy metal and halogen.   9. The step (e) comprises the step of contacting the recovered heavy metal and halogen with a strongly basic anion exchange resin in hydroxide or acetate form to form purified heavy metal and halogen. The method described in 1. 10. The method of claim 9, further comprising f) using the purified heavy metal and halogen in the chemical process.   The method according to any one of claims 1 to 10, wherein the heavy metal is Co, Mn, Ce, Zr, Hf, or a combination thereof.   The method according to claim 1, wherein the chemical process is a terephthalic acid production process, an isophthalic acid process, and a trimellitic acid process.   The method according to claim 1, wherein the halogen is Br.   The method according to any one of claims 1 to 13, wherein the anion exchange resin in the step (a) is a halogenated anion exchange resin.   The method according to claim 14, wherein the anion exchange resin is a brominated anion exchange resin.   The method according to any one of claims 1 to 15, wherein the chelation exchange resin in step (b) is an imidodiacetic acid resin. A method of removing and recovering i) at least one heavy metal selected from the group consisting of Co, Mn, Ce, Zr, Hf and combinations thereof, and bromine from a liquid stream in a chemical process,
a) contacting said liquid stream with a strongly basic anion exchange resin in halide form;
b) contacting the effluent stream from step (a) with a chelating cation exchange resin;
c) contacting the anion exchange resin with an anion exchange resin regeneration solution containing water and acetic acid to regenerate the anion exchange resin in step (a) to form recovered heavy metals and bromine;
d) regenerating the chelated cation exchange resin by contacting the chelated cation exchange resin with a regeneration primer containing HBr, and then contacting the chelated cation exchange resin with a regeneration solution containing water. Form recovered heavy metals and bromine,
e) Purifying the recovered heavy metal and bromine by contacting the recovered heavy metal and bromine with a strongly basic anion exchange resin in a hydroxide form to obtain the purified heavy metal and bromine. And f) a removal and recovery process comprising the step of using said purified heavy metal and bromine in said chemical process.   The process according to claim 16, wherein the strongly basic anion exchange resin in step (a) is a brominated anion exchange resin.   The method according to claim 16 or 17, wherein the chelating cation exchange resin is an imidodiacetic acid resin. A method of removing and recovering i) at least one heavy metal selected from the group consisting of Co, Mn and combinations thereof and ii) bromine from a liquid stream during the PTA process,
a) contacting the liquid stream with a chelating cation exchange resin;
b) regenerating the chelated cation exchange resin by contacting the chelated cation exchange resin with a regeneration primer containing HBr and then contacting the chelated cation exchange resin with a regeneration solution containing water. Form recovered heavy metals and bromine,
c) Purifying the recovered heavy metal and bromine by contacting the recovered heavy metal and bromine with a strongly basic anion exchange resin in a hydroxide form to obtain the purified heavy metal and bromine. D) a removal and recovery process comprising the step of using said purified heavy metal and bromine in said PTA process.   21. The method of claim 20, wherein the chelating cation exchange resin is an imidodiacetic acid resin.

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