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WO2005115956A1 - Procédé servant à produire de l'acide téréphtalique de pureté élevée - Google Patents

Procédé servant à produire de l'acide téréphtalique de pureté élevée Download PDF

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Publication number
WO2005115956A1
WO2005115956A1 PCT/JP2005/009461 JP2005009461W WO2005115956A1 WO 2005115956 A1 WO2005115956 A1 WO 2005115956A1 JP 2005009461 W JP2005009461 W JP 2005009461W WO 2005115956 A1 WO2005115956 A1 WO 2005115956A1
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Prior art keywords
terephthalic acid
pressure
mother liquor
cooling
solid
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PCT/JP2005/009461
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English (en)
Japanese (ja)
Inventor
Katsuhiko Fukui
Motoki Numata
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Mitsubishi Chemical Corp
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Mitsubishi Chemical Corp
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Priority to CN2005800174093A priority Critical patent/CN1960960B/zh
Publication of WO2005115956A1 publication Critical patent/WO2005115956A1/fr
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation

Definitions

  • the present invention relates to a method for producing high-purity terephthalic acid.
  • the process is as follows.
  • the raw material para-xylene is air-oxidized to terephthalic acid with a catalyst in a high-temperature, high-pressure acetic acid solvent.
  • an intermediate 4 carboxybenzaldehyde is by-produced together with terephthalic acid.
  • the slurry containing these is crystallized and separated into solid and liquid to obtain crude terephthalic acid crystals.
  • the crude terephthalic acid crystals are dissolved in water under high-temperature and high-pressure conditions to form an aqueous solution, and 4-carboxybenzaldehyde contained in the crude terephthalic acid is hydrogen reduced to paratoluic acid having high water solubility.
  • the mixture is depressurized and cooled, and terephthalic acid with low water solubility is crystallized from the aqueous solution and recovered as high-purity terephthalic acid.
  • Patent Document 2 JP-A-5-58948
  • the present invention increases the recovery rate of the secondary crystals precipitated by cooling the primary separation mother liquor and increases the secondary separation mother liquor having a low turbidity (SS concentration). It is an object of the present invention to provide a method for producing high-purity terephthalic acid, which can obtain terephthalic acid. Another object of the present invention is to provide a method for producing high-purity terephthalic acid that can suppress formation of deposits in the system that cause blockage and generation of lumps during cooling treatment.
  • the present inventors have conducted intensive studies to solve the above problems, and as a result, found that the above problems can be solved by depressurizing and cooling the primary separated mother liquor in multiple stages and crystallizing it, and completed the present invention.
  • the gist of the present invention resides in the following (1) to (11).
  • a dissolving step of dissolving the above crude terephthalic acid in an aqueous solvent under high temperature and pressure to obtain a crude terephthalic acid aqueous solution (b)
  • Cooling is performed by using a plurality of cooling tanks for cooling by evaporating the water solvent in the mother liquor by lowering the pressure, the last of which is reduced to below atmospheric pressure, and the temperature of the last cooling tank is reduced to 40 to A method for producing high-purity terephthalic acid at 70 ° C.
  • At least one of the cooling tanks used in the crystallization step (f) has a stirring blade having a distance from the inner wall of the cooling tank of 10 mm or more and 50 mm or less. )) The method for producing high-purity terephthalic acid according to any one of the above).
  • the downstream side of the filter of the filter is set at a pressure higher than the atmospheric pressure, and the upstream side of the filter of the filter is set at a pressure higher than that of the downstream side of the filter, and the filtration is performed.
  • the separated mother liquor obtained in the filtration step (g) is brought into contact with a synthetic adsorbent to remove paratoluic acid, and then provided to the dissolution step (b) in the above (6) to (8).
  • (11) The method for producing high-purity terephthalic acid according to any one of (6) to (10), wherein the concentration of the suspended substance in the separated mother liquor obtained in the filtration step (g) is 200 mg ZL or less. .
  • the primary separation mother liquor is cooled to increase the recovery rate of secondary crystals precipitated, and a secondary separation mother liquor with low turbidity (SS concentration) is obtained.
  • SS concentration turbidity
  • a method for producing high-purity terephthalic acid it is possible to provide a method for producing high-purity terephthalic acid, which can suppress formation of deposits in the system that cause blockage and generation of lumps during cooling treatment.
  • FIG. 1 is a flowchart showing an example of a method for producing terephthalic acid which is effective in the present invention.
  • the method for producing high-purity terephthalic acid of the present invention comprises the steps of: (a) preparing a crude terephthalic acid containing 4-carboxybenzaldehyde by oxidizing noraxylene;
  • a dissolving step of dissolving the above crude terephthalic acid in an aqueous solvent under high temperature and pressure to obtain a crude terephthalic acid aqueous solution (b)
  • crude terephthalic acid is produced by subjecting para-xylene to liquid phase oxidation with molecular oxygen in an acetic acid solvent in the presence of a catalyst.
  • a catalyst which is conventionally known to be usable in this reaction is used.
  • a heavy metal such as a cobalt compound, a manganese compound, an iron compound, and a chromium compound is used.
  • bromine compounds are present in the reaction system in a dissolved state. Among them, a combination of a cobalt compound or a manganese compound and a bromine compound is preferred.
  • these compounds are usually used in such a manner that the concentration of SlO in the Connort reactor is 10 to 5000 ppm, the manganese atom is 10 to 5000 ppm, and the bromine atom is 10 to 10000 ppm.
  • molecular oxygen a mixed gas of an inert gas and oxygen is usually used, and for example, air or oxygen-enriched air is used.
  • the molar ratio of molecular oxygen to paraxylene supplied to the reactor is usually 3 to 20 times, preferably 2 to 4 times.
  • the ratio of para-xylene to acetic acid supplied to the reactor is usually 1 to 50% by weight.
  • the water concentration in the reaction system is usually 5 to 20% by weight, preferably 5 to 15% by weight.
  • the temperature of the oxidation reaction is usually from 160 to 260 ° C, preferably from 170 to 210, and the pressure is usually from 0.5 to higher as long as the reaction system can maintain a liquid phase at a reaction temperature or higher. 5 MPa, preferably 1-2 MPa, and the residence time is usually 10-200 minutes.
  • terephthalic acid generated in the oxidation reaction step usually precipitates as crystals to form a slurry.
  • terephthalic acid may be dissolved.
  • a crystallization step of cooling the reaction solution or the like is provided to precipitate terephthalic acid to form a slurry.
  • the slurry is subjected to solid-liquid separation to obtain crude terephthalic acid crystals.
  • the terephthalic acid slurry obtained in the oxidation reaction step is in a pressurized state
  • the terephthalic acid slurry may be subjected to solid-liquid separation as it is, or may be subjected to depressurized cooling or the like, followed by solid-liquid separation.
  • solid-liquid separation if it is possible to separate the crystal and the mother liquor, filtration, centrifugation and the like can be mentioned. Wash and dry as necessary After drying, crude terephthalic acid crystals (crude terephthalic acid C) are obtained.
  • the "crude terephthalic acid” in the present invention means terephthalic acid containing 1000 to 1 OOOOppm of 4 carboxybenzaldehyde.
  • the oxidation step (a) when the paraxylene A is oxidized, the oxidization reaction of one of the alkyl groups, which is different from the terephthalic acid alone, completely proceeds.
  • 4 By-products including carboxybenzaldehyde hereinafter abbreviated as "4CBA" are produced.
  • Crude terephthalic acid C power also removes these by-products and performs the following steps to obtain high-purity terephthalic acid.
  • the crude terephthalic acid C is slurried with water D in the slurrying tank 12, and the starting slurry E is heated to a high temperature and high pressure by a pump 12a and a heater 12b to be dissolved in water. E '.
  • the above terephthalic acid has a low solubility in water.
  • the above high temperature and high pressure require that the terephthalic acid can be dissolved in water. This temperature is preferably 230 ° C or more and 320 ° C or less depending on the slurry concentration. 2 If the temperature is lower than 30 ° C, the solubility is not sufficient. If the temperature exceeds 320 ° C, energy is wasted.
  • this pressure needs to be a pressure that can maintain the liquid phase in the above temperature range, and is desirably 2.8 MPa or more and 11.3 MPa or less.
  • the concentration of the slurry obtained in the dissolving step (b) is usually 20 to 40 wt%, preferably 25 to 35 wt%. If the slurry concentration is too high, clogging in the apparatus will occur, and if the slurry concentration is too low, the amount of mother liquor will increase, and the equipment corresponding to the production volume will increase in size. From the viewpoint of preventing clogging, it is preferable that the slurry concentration is kept constant.
  • the aqueous solution E ′ of terephthalic acid obtained in the above-mentioned dissolution step is sent to the hydrogenation reactor 13 and catalytically reduced with the introduced hydrogen F in the presence of a catalyst, A reduction reaction solution G is obtained.
  • the conditions of this catalyst and the conditions in the hydrogenation reactor 13 must be such that the above 4CBA is reduced and the above terephthalic acid is not reduced. This is because the above 4CBA contained in the aqueous solution E 'is reduced to paratoluic acid having high water solubility. It is desirable to carry out this reduction at the highest possible rate.
  • the hydrogenation catalyst examples include ruthenium, rhodium, palladium, platinum, osmium, etc., groups 8 to 10 (IUPAC inorganic A metal catalyst is used (according to the revised chemical nomenclature (1998)), and is usually used as a fixed bed supported on a carrier such as activated carbon. Of these, palladium supported on activated carbon is preferred.
  • the hydrogenation temperature is usually 260-320. C, preferably 270-300.
  • the partial pressure of C and hydrogen is usually 0.5 to 20 kgZcm 2 G.
  • the reduction reaction solution G obtained in the reduction step (c) is introduced into the crystallization tank 14, and the temperature is maintained within a range where the above-mentioned paratoluic acid remains dissolved. And the pressure is reduced to crystallize the above terephthalic acid to form slurry H.
  • the temperature of the last crystallization tank 14 may be controlled to a temperature condition such that paratoluic acid does not co-crystallize with terephthalic acid.
  • the temperature must be 120 ° C or higher and 200 ° C or lower. It is desirable that the temperature be between 180 ° C and 180 ° C.
  • the pressure at this time needs to be 0.20 MPa or more and 1.56 MPa or less, and preferably 0.27 MPa or more and 1. OOMPa or less. If the temperature and pressure are lower than those conditions, paratoluic acid, not only terephthalic acid alone, will co-crystallize, lowering the purity of the resulting high-purity terephthalic acid crystals. On the other hand, if the temperature and pressure are kept higher than these conditions, the crystallization amount of terephthalic acid obtained is reduced, and the efficiency is reduced.
  • the slurry H is introduced into a solid-liquid separator, and the slurry H power is used as a primary separation mother! 3 ⁇ 4 to obtain a high-purity terephthalic acid cake containing the high-purity terephthalic acid crystals.
  • This high-purity terephthalic acid cake is preferably washed with a washing device and then dried to obtain primary crystals of high-purity terephthalic acid crystals. It is more preferable that the processes are performed collectively in the solid-liquid separation and washing device 15 because the process can be simplified.
  • the operation when the slurry H is separated into solid and liquid by one solid-liquid separation and washing device 15 and washed is as follows.
  • the slurry H and the washing liquid I are introduced into the solid-liquid separation and washing device 15.
  • As the cleaning solution I water is more preferable.
  • the slurry H is subjected to solid-liquid separation, and the separated cake is washed with a washing solution I to obtain a high-purity terephthalic acid cake L as a primary separation mother! 3 ⁇ 4 [Separate from the primary mother. 3 ⁇ 4 Discharge the cleaning effluent K, which mainly consists of the components of the cleaning liquid I.
  • the primary separation discharged from the solid-liquid separation and washing device 15 The temperature of the mother!
  • 3 ⁇ 4 is the same as the crystallization conditions in the first crystallization step (d), and is preferably 120 ° C or more and 200 ° C or less, more preferably 130 ° C or more and 180 ° C or less.
  • the pressure should be higher than the pressure of the final crystallization tank in the crystallization step (d) in order to suppress the temperature decrease due to the pressure release. Specifically, the pressure is desirably 0 to 1 MPa higher than the pressure of the final crystallization tank in the crystallization step (d). In the solid-liquid separation step (e), it is desirable to operate so that the supplied slurry H is not cooled.
  • Examples of the solid-liquid separation and washing device 15 capable of performing solid-liquid separation and washing in a batch as described above include, for example, a screen bowl type centrifuge, a rotary vacuum filter, a horizontal belt filter, etc., and particularly preferably a screen. It is a bowl type centrifuge.
  • the high-purity terephthalic acid crystal L obtained by drying the high-purity terephthalic acid cake L in the drying device 16 to remove the remaining adhesion liquid can be obtained.
  • the drying device 16 is, for example, a rotary drier or a fluidized bed drier, and is operated at a drying outlet operation temperature of 70 ° C to 180 ° C using a heat source such as steam in the presence of ventilation gas. .
  • the above primary separation mother! 3 ⁇ 4 [and the washing effluent K still contain active ingredients, and it is necessary to recover as much of these as possible to make high-purity terephthalic acid crystals.
  • the active ingredient refers to the terephthalic acid and another compound that can be converted to the terephthalic acid by acidification or the like such as paratoluic acid. Including both.
  • the solid content refers to a precipitated component of the active ingredient.
  • washing discharge K has a low content of paratoluic acid, it is desirable to return it directly as the solvent in the dissolving step (b).
  • washing effluent K contains a solid
  • solid-liquid separation may be performed by another solid-liquid separator before returning to the dissolving step (b). This is because if the solid-liquid separation and washing are performed at the same time by the solid-liquid separation and washing device 15 as described above, the omission is likely to occur, and the washing effluent K may contain solids. . Further, if crystallization is performed in advance before separation by the above-mentioned solid-liquid separation device, the amount of components that can be recovered by solid-liquid separation is improved. At that time, the solid content may be collected by sending it to the crystallization tank 14 or the like, or separated. The liquid component may be used as the solvent used in the slurrying tank 12 described above.
  • the primary separated mother bite is cooled using a plurality of pressure relief cooling tanks, and the terephthalic acid contained in the primary separated mother bite is contained. Crystallize secondary crystals that have the same strength as acid-paratoluic acid and collect them.
  • the multi-stage means that two or more pressure relief cooling tanks are installed in series, and in each tank, dissolved components are deposited by sequentially lowering the respective temperatures according to the pressure.
  • the pressure-relieving cooling tank is a tank whose pressure is lower than the pressure of the liquid to be introduced, and the boiling point of the main component of the liquid at the pressure in the tank is equal to or lower than the temperature of the liquid before introduction. It means something that is When the liquid is introduced into the pressure-release cooling tank, a part of the liquid evaporates, and the rest of the liquid is cooled to the boiling point under the changed pressure. At this time, if the liquid is a solution, the solute that exceeds the solubility after cooling is crystallized.
  • the first pressure-release cooling tank 17, which is the first pressure-release cooling tank has a pressure equal to or higher than the atmospheric pressure and the solid-liquid separation step ( e) Primary separation mother discharged from! ⁇
  • the desired temperature is below 100 ° C and the primary separation mother discharged from the solid-liquid separation step (e)! (E.g., if the pressure is below 100 ° C (e.g., the pressure is reduced to 100 ° C and the temperature is lower than the temperature at the time of solid-liquid separation in the solid-liquid separation step (e)). Is preferable.).
  • At least one of the above-described multi-stage pressure-reducing cooling tanks is desirably provided with a stirring blade having a distance from the inner wall of the pressure-reducing cooling tank of 10 mm or more and 50 mm or less. Better.
  • the stirring blade is an anchor-type stirring blade that is more desirable as the portion adjacent to the inner wall of the pressure-release cooling tank at the above-mentioned interval is longer. Since the purity of the terephthalic acid is relatively low in the above-mentioned pressure-reducing cooling bath, terephthalic acid is crystallized. There is. When the liquid in the vicinity of the wall is appropriately flowed by the stirring blade rotating near the wall of the tank, the adhesion of the terephthalic acid or the like to the wall can be suppressed.
  • the distance between the stirring blade and the wall surface is desirably 10 mm or more, because if it is too close, the pressure relief cooling tank itself may be damaged.
  • the first pressure relief cooling tank 17, which is the first pressure relief cooling tank is most likely to have the largest amount of crystallization. More desirable.
  • the above-described stirring blades may be provided in all of the plurality of pressure-reducing cooling tanks.
  • the rotation speed of the anchor-type stirring blade is 3.Orpm or more, The speed is preferably 30 rpm or less, more preferably 5 rpm or more and 20 rpm or less. 3. If the rotation speed is less than Orpm, the effect of stirring cannot be fully exhibited, and the crystallized crystals may adhere to the inner wall side surface below the liquid surface as a lump. On the other hand, a speed of 30 rpm is sufficient for agitation, and even if the speed is higher than that, it is a waste of energy. 3 ⁇ 4 is scattered in the cooling tank, causing lumps to adhere above the liquid level in the tank.
  • the pressure in the final pressure-reducing cooling tank 18, which is the last pressure-reducing cooling tank among the above-described multiple pressure-releasing cooling tanks, is reduced to below atmospheric pressure, and the temperature of the cooling tank is reduced.
  • the pressure in the final pressure relief cooling tank 18 is 0.00 It is 7 MPa or more and 0.03 MPa or less, preferably 0.02 to 0.03 MPa. If the pressure exceeds 0.03 MPa and the temperature is too high, the crystallization may not be thorough and the recovery may be insufficient. On the other hand, if the pressure is less than 0.007 MPa and the temperature is too low, the pressure on the final pressure-reducing cooling tank 18 may be too large because the degree of pressure reduction is high.
  • a single or a plurality of pressure-release cooling tanks may be provided between the first pressure-release cooling tank 17 and the final pressure-release cooling tank 18 to perform stepwise crystallization. ! ⁇ .
  • the secondary slurry O obtained by crystallizing the terephthalic acid or the like in the second crystallization step (f) is introduced into the filter 19 as a filtration step (g), and the secondary separation mother liquor is obtained. P and secondary crystal Q are separated into solid and liquid.
  • the filter 19 used here can set the downstream side of the filter to a pressure state higher than the atmospheric pressure, and further, can set the upstream side of the filter to a pressure higher than that of the downstream side of the filter, and can also set the forward direction. It is desirable that solid-liquid separation be performed by cake filtration because filtration can be easily performed.
  • the above-mentioned secondary slurry O is easier to handle and handle by crystallizing it in the above-mentioned multi-stage pressure-reducing cooling tank! / Although it is easy to adhere and has properties, it is difficult for ordinary filtration. This is because it is difficult to progress.
  • the upstream side of the filter refers to the side to which the second crystallization step (f) force has been sent
  • the downstream side of the filter refers to the side for discharging the secondary separation mother liquor P
  • the forward direction refers to the secondary side. This refers to the direction in which the flow of the slurry O or the secondary separation mother liquor P is directed from the upstream side of the filter to the downstream side of the filter.
  • cake filtration particles are trapped on the filter pores by a cross-linking phenomenon, a filter cake layer is formed on one surface of the filter shortly after the start of filtration, and the cake layer is used as a filter for the subsequent filtration. This is a mechanism in which filtration proceeds while acting.
  • Examples of the filter 19 operated in this manner include a Fundaback filter manufactured by Ishikawajima-Harima Heavy Industries, Ltd., and a cricket filter manufactured by Tsukishima Kikai Co., Ltd.
  • the secondary crystal Q contains not only terephthalic acid but also partially reduced impurities such as paratoluic acid. These cannot be used as such as terephthalic acid products. Therefore, these impurities are removed by the above-mentioned terephthalic acid by oxidizing in the above-mentioned acidifying step (a).
  • Tallic acid can be used, and the overall yield of the method for producing high-purity terephthalic acid according to the present invention can be improved.
  • the above-mentioned secondary separated mother liquor P preferably has a suspended substance concentration of 200 mg ZL or less, more preferably 100 mg ZL or less, and still more preferably 50 mg ZL or less.
  • the suspended substance concentration means the weight of suspended matter such as paratoluic acid which is dispersed without being dissolved in the solvent with respect to the total weight of the secondary separation mother liquor P, and is described in JIS K 0101. Analyzed according to the method. At least a part of the secondary separation mother liquor P is discharged out of the system because the concentration of impurities in the system is not too high, so that paratoluic acid contained in the secondary separation mother liquor P is discarded.
  • the synthetic adsorbent an organic synthetic adsorbent is usually used.
  • SEPABEADS SP825, SP850, SP207 SEPABEADS is a registered trademark of Mitsubishi Chemical Corporation
  • AMBERLITE XAD-4, XAD-16 AMBERLIT ⁇ is a registered trademark of Rohm & Haas Company
  • a synthetic adsorbent, an acrylic synthetic adsorbent such as DIAION HP2MG (DIAION is a registered trademark of Mitsubishi Chemical Corporation), AMBERLITE XAD-7, XAD-8, etc. can be used.
  • a non-polar organic synthetic adsorbent especially a synthetic adsorbent having a porous copolymer power of a monovinyl conjugate and a polyvinyl conjugate, especially a styrene-dibutylbenzene synthetic adsorbent is used.
  • paratoluic acid has a benzene ring, it is easily adsorbed by a styrene-divinylbenzene-based synthetic adsorbent.
  • the specific surface area of the adsorbent is usually 400 ⁇ 1500m 2 Zg, preferably 600 ⁇ 1000m 2 Zg, pore volume is typically 0. 5 ⁇ 3mLZg, preferably 1. 0 ⁇ 2.
  • OmL / g, pore size is usually 10 to : LOOOA, preferably 50-50 ⁇ .
  • the adsorbent is usually packed in the adsorption tower so that the height of the packed bed is about 1.5 to 4. Om. Depending on when the supply of the liquid to be treated is stopped, in general, if the height of the packed bed is too low, the utilization efficiency of the adsorbent decreases.
  • the supply rate of the liquid to be treated to the adsorption tower is typically 0.5 to 30 mZhr for LV. , SV is usually 0. 5 ⁇ 20hr _1.
  • the P in the secondary separation mother liquor that has been subjected to the adsorption treatment has a reduced paratoluic acid concentration, so that it can be easily reused in the production step, preferably as a solvent in the dissolution step or a washing liquid for the separation cake after the solid-liquid separation step.
  • paratoluic acid is an intermediate in the conversion of paraxylene to terephthalic acid, and the paratoluic acid adsorbed on the synthetic adsorbent is recovered using a desorbing solution, and It is preferable to supply to the process ⁇ .
  • S Suspended substance (mgZD, a: Weight of filter medium and watch glass containing suspended substance (mg), b: Weight of filter medium and watch glass (mg), V: Sample (ml)
  • An acetic acid solution containing para-xylene and a catalyst an acetic acid solution of cobalt acetate and manganese acetate and hydrogen bromide
  • a separated mother liquor recycled from a subsequent solid-liquid separation step and air are continuously supplied to the stirring tank.
  • an oxidizing reaction was performed at an operating temperature of 190 ° C. and an operating pressure of 1.23 MPa (absolute pressure) while adjusting the liquid level so that the residence time was 1 hour.
  • the distillate vapor is finally cooled to 40 ° C by a multi-stage condenser, and the oxygen concentration in the exhaust gas is adjusted to 2.5 vol%.
  • the operation was carried out after setting.
  • the condensate obtained from each condenser was integrated and refluxed to the oxidation reactor, and a part of the condensate was withdrawn so that the concentration of water in the mother liquor of the slurry withdrawn was 10% by weight.
  • the slurry concentration of the slurry from which the reactor power was also extracted was 35% by weight, and the concentration of cobalt Z manganese Z bromine in the reaction mother liquor was 300Z300Z1000ppm by weight.
  • the slurry from which the power of the reactor was also withdrawn was continuously supplied to a stirring tank together with air, and at an operating temperature of 181 ° C, an operating pressure of 1.15 MPa (absolute pressure), and a residence time of 15 minutes.
  • the low-temperature re-oxidation reaction was performed while adjusting the liquid level so as to be as follows.
  • the distillate steam was finally cooled to 40 ° C by a multi-stage condenser, and the operation was performed with the oxygen concentration in the exhaust gas adjusted to 6 vol%.
  • the condensed liquid obtained from each condenser was integrated and refluxed to the low-temperature re-oxidation reactor.
  • the slurry from which the power of the low-temperature refining reactor was extracted was crystallized to 90 ° C, and the slurry obtained by the crystallization was supplied to a rotary vacuum filter to perform solid-liquid separation and washing. I got it.
  • the operating pressure was atmospheric pressure.
  • the separated crude terephthalic acid cake was dried with a steam rotary dryer to obtain crude terephthalic acid crystals.
  • This crude terephthalic acid was supplied to the process for producing high-purity terephthalic acid shown in Fig. 1.
  • aqueous solution E ' containing 30% by weight of crude terephthalic acid at high temperature and pressure was obtained.
  • the temperature and pressure of the aqueous solution E ′ sent to the hydrogenation reactor 13 were 290 ° C. and 8.7 MPa (89 kgfZcm 2 ′ gauge), respectively.
  • the crystallization tank 14 in which the five crystallization tanks are connected in series is cooled stepwise by depressurization evaporation, and finally cooled to a temperature of 155 ° C. After cooling to C, the solute was crystallized.
  • the slurry H obtained by the crystallization is separated into a high-purity terephthalic acid cake L containing primary crystals and a primary separation mother! 3 ⁇ 4 [The high-purity terephthalic acid cake L was washed with washing water, dried in a drier 16 and recovered as high-purity terephthalic acid crystals M.
  • the primary separating mother bite is reduced in pressure to the atmospheric pressure in the first pressure relief cooling tank 17 provided with the anchor type stirring blades, and is then cooled by releasing the pressure to 100 ° C.
  • the crystallization to be the second crystallization step (f) was performed.
  • the rotation speed of the anchor type stirring blade was 10 rpm, and the gap between the anchor type stirring blade and the side surface of the inner wall was 10 mm.
  • the obtained intermediate slurry N at 100 ° C was finally discharged with a steam ejector. It was introduced into the pressure cooling tank 18, the operating pressure was set to 0.02 MPa, and the pressure was reduced to 60 ° C. under reduced pressure.
  • the secondary slurry O thus obtained was charged as a filter 19 into a Fundaback filter (R56-86-25) manufactured by Ishikawa-Harima Heavy Industries, Ltd., and was subjected to solid-liquid separation.
  • the suspended substance concentration of the secondary mother liquor P obtained here was measured according to the above method, and was 30 mgZl.
  • the primary separated mother liquor is cooled to increase the recovery rate of secondary crystals precipitated, and a secondary separated mother liquor having a low turbidity (SS concentration) is obtained.
  • SS concentration turbidity
  • a method for producing high-purity terephthalic acid it is possible to provide a method for producing high-purity terephthalic acid, which can suppress formation of deposits in the system that cause blockage and generation of lumps during cooling treatment. The industrial value of the present invention is remarkable.

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Abstract

Procédé servant à produire de l'acide téréphtalique de pureté élevée lequel comprend : une étape d'oxydation (a) dans laquelle on oxyde du p-xylène pour obtenir de l'acide téréphtalique brut ; une étape de dissolution (b) dans laquelle on dissout l'acide téréphtalique brut dans un solvant à base d'eau pour obtenir une solution aqueuse de l'acide téréphtalique brut ; une étape de réduction (c) dans laquelle on met en contact la solution aqueuse de l'acide téréphtalique brut avec de l'hydrogène pour obtenir un liquide résultant d'une réaction de réduction ; une étape de cristallisation (d) dans laquelle on refroidit le liquide résultant d'une réaction de réduction pour faire cristalliser de l'acide téréphtalique de pureté élevée ; une étape de séparation solide-liquide (e) dans laquelle on soumet la suspension épaisse obtenue dans l'étape de cristallisation (d) à une séparation solide-liquide ; et une étape de cristallisation (f) dans laquelle on refroidit la liqueur mère séparée obtenue dans l'étape de séparation solide-liquide (e) pour former des cristaux constitués principalement de l'acide téréphtalique et d'acide p-toluique contenus dans la liqueur mère, dans lequel on effectue le refroidissement de la liqueur mère en utilisant deux ou plus de deux cuves qui ont une pression réduite de façon à faire évaporer le solvant à base d'eau contenu dans la liqueur mère et dans lequel la dernière cuve de refroidissement est régulée de façon à ce qu'elle ait une pression inférieure à la pression atmosphérique et une température de 40-70°C.
PCT/JP2005/009461 2004-05-28 2005-05-24 Procédé servant à produire de l'acide téréphtalique de pureté élevée Ceased WO2005115956A1 (fr)

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CN102203042A (zh) * 2008-10-31 2011-09-28 英威达技术有限公司 改进的纯羧酸过滤
WO2012114434A1 (fr) * 2011-02-21 2012-08-30 株式会社日立プラントテクノロジー Procédé de traitement d'une liqueur mère d'acide téréphtalique purifié
CN103408421B (zh) * 2013-08-21 2015-10-28 深圳市超纯环保股份有限公司 对苯二甲酸的提纯方法
WO2018051775A1 (fr) * 2016-09-14 2018-03-22 三菱瓦斯化学株式会社 Procédé de production d'acide téréphtalique à haute pureté
TWI708761B (zh) 2019-09-26 2020-11-01 遠東新世紀股份有限公司 製造對苯二甲酸的方法
CN112774579B (zh) * 2020-12-28 2023-05-30 南京延长反应技术研究院有限公司 一种粗对苯二甲酸加氢精制的智能微界面反应系统及方法
CN112774592B (zh) * 2020-12-28 2023-05-12 南京延长反应技术研究院有限公司 一种粗对苯二甲酸加氢精制的微界面反应系统及方法

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JPH07507291A (ja) * 1992-05-29 1995-08-10 イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー 精製されたテレフタル酸の製造のための方法
JPH11228492A (ja) * 1998-02-13 1999-08-24 Hitachi Ltd テレフタル酸の回収方法
WO2002028499A1 (fr) * 2000-10-02 2002-04-11 Mitsubishi Gas Chemical Company, Inc. Procede de cristallisation

Patent Citations (3)

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JPH07507291A (ja) * 1992-05-29 1995-08-10 イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー 精製されたテレフタル酸の製造のための方法
JPH11228492A (ja) * 1998-02-13 1999-08-24 Hitachi Ltd テレフタル酸の回収方法
WO2002028499A1 (fr) * 2000-10-02 2002-04-11 Mitsubishi Gas Chemical Company, Inc. Procede de cristallisation

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