Method of producing highly pure terephthalic acid

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing highly pure terephthalic acid which involves the following steps: (a) an oxidation reaction, where p-xylene is oxidised in an acetic acid solution in the presence of a catalyst to form terephthalic acid, (b) obtaining crystals of crude terephthalic acid, where the suspension containing the precipitate of the obtained terephthalic acid is separated into a solid phase and a liquid to obtain crystals of crude terephthalic acid, (c) hydrogenation step, where crystals of crude terephthalic acid are dissolved in water to form an aqueous solution which is hydrogenated, (d) crystallisation of highly pure terephthalic acid, where terephthalic acid is crystallised from the hydrogenated aqueous solution to form a suspension of highly pure terephthalic acid, (e) obtaining crystals of highly pure terephthalic acid, where the suspension of highly pure terephthalic acid is separated into a solid phase and a liquid to obtain crystals of highly pure terephthalic acid and a primary mother solution, and (f) extraction of p-toluic acid from the primary mother solution and taking it to the oxidation reaction step, where the p-toluic acid extraction step includes the following steps: (I) adsorption step, where primary or secondary mother solution, obtained by cooling the primary mother solution in order to separate the solid phase and liquid, is fed in form of treated liquid into an adsorption column filled with an adsorption agent, where the p-toluic acid breakthrough time is greater than that of benzoic acid, for adsorption of p-toluic acid and benzoic acid from the treated liquid on the adsorption agent, (II) cutting supply of the treated liquid into the adsorption column for at a certain moment in time when concentration of benzoic acid in the effluent from the adsorption column reaches at least 10% of the concentration of benzoic acid in the treated liquid, (III) desorption step, where a desorption agent in form of acetic acid, methylacetate or their mixture is fed into the adsorption column for desorption of the adsorbed p-toluic acid and (IV) circulation step, where p-toluic acid contained in the desorption agent flows from the adsorption column and taken to the oxidation reaction step.

EFFECT: design of a method of obtaining highly pure terephthalic acid through selective extraction of p-toluic acid from waste water currently released, and use of the waste water as raw material for producing terephthalic acid.

19 cl, 6 dwg, 5 ex, 1 tbl

 

The technical FIELD

The present invention relates to a method of production of high-purity terephthalic acid. More specifically, the invention concerns a method of obtaining high-purity terephthalic acid by oxidizing p-xylene, where p is tolarova acid formed as a by-product, is extracted and fed to a stage of oxidation.

The LEVEL of TECHNOLOGY

Currently, high-purity terephthalic acid is obtained in a large scale way, including the relevant stages, including the stage of the oxidation reaction by the oxidation of p-xylene in explicitation a solvent to form terephthalic acid; a step for crystals of crude terephthalic acid from the suspension obtained at the stage of the oxidation reaction; stage purification by hydrogenation with obtained by dissolving crude terephthalic acid in hot water and its hydrogenation to achieve cleanup; stage crystallization of high-purity terephthalic acid by crystallization of high-purity terephthalic acid from the solution after exit from the stage of purification by hydrogenation; the stage of obtaining crystals of high-purity terephthalic acid by removing the crystallized high-purity terephthalic acid; and the stage of washing and drying washing the obtained high-purity terephthalic acid with water and drying.

Appreciable quantities of the content of inorganic fillers substances in the form of a water-soluble by-products, for example, p-Truelove acid and benzoic acid, are contained in the wastewater of these stages, especially stage of obtaining crystals of high-purity terephthalic acid, namely in the mother solution after separation of the crystals. If the waste water is discharged into the environment, as they are polluting the environment, and, therefore, they must be reset after reducing the concentration of organic substances using the apparatus of mining wastewater. This processing requires huge expenses.

Therefore, patent document 1 proposes a method in which after removal of insoluble organic matter in wastewater by filtering using a filter heavy metals are removed using ion exchange resin and dissolved organic matter extracted using reverse osmosis systems.

Also, non-patent document 1 proposes that these waste waters, namely the mother liquor after separation of the crystals was treated adsorbing agent to remove organic substances, such as p-tolarova acid and benzoic acid, and then re-used as hot water for dissolving crude terephthalic acid at the stage of purification by hydrogenation.

Patent document 1: JP-T-2003-507156

Non-patent document 1: P.K. Khachane et al., Separation Science and Technology, Vol. 38, No. 1, p.3-111, 2003.

Description of the INVENTION

The PROBLEM solved by THIS INVENTION

Now, as described above, significant amounts of p-Truelove acid and benzoic acid are contained in the wastewater as p-tolarova acid into terephthalic acid by oxidation, if p-tolarova acid in the wastewater can be extracted and directed to the phase oxidation reaction, it becomes possible to increase the yield of terephthalic acid.

However, in the method of patent document 1 p-Truelove acid extract in the form of a mixture of benzoic acid. Accordingly, if the extracted p-tolarova acid is fed to the phase oxidation reaction, the concentration of benzoic acid in the reaction system is increased due to the insertion of benzoic acid and a significant amount of benzoic acid is obtained in high purity terephthalic acid. If benzoic acid is contained in terephthalic acid, upon receipt of the polyester using it as source material there is a probability that the degree of polymerization of the obtained polyester reaches a prescribed value; and the likelihood is that there will be a coloring of polyester. Accordingly, p-tolarova acid extracted in the form of a mixture of benzoic acid, cannot be reused as a source is about material for terephthalic acid such as she is. Therefore, we need a method for efficient extraction of only p-Truelove acid from wastewater containing benzoic acid and p-Truelove acid.

A MEANS FOR SOLVING these PROBLEMS

Non-patent document 1 describes that benzoic acid and p-tolarova acid adsorbed on a porous adsorbing agent from the aqueous solution and that the adsorbed benzoic acid and p-tolarova acid can decorrelates acetic acid or acetate. However, this document does not describe that benzoic acid and p-tolarova acid can be separated using a porous adsorbing agent.

Feeding an aqueous solution containing benzoic acid and p-Truelove acid, in the adsorption column filled with the data of porous adsorbing agent, the inventors have studied the transition of these compounds in the effluent, resulting from the adsorption column. In the result it was found that in the beginning all of benzoic acid and p-tolarova acid adsorbed, and therefore, the liquid not containing any of them, arises from the adsorption column; however, when the flow of an aqueous solution continues, benzoic acid appears in affluence, and the concentration of benzoic acid in effluent gradually increases, and when the concentration becomes DOS is high enough, p-tolarova acid first appears in affluence, and its concentration is gradually increased, which led to this invention.

The mentioned phenomenon shows that p-tolarova stronger acid is adsorbed on the porous adsorbing agent than benzoic acid, and that after adsorption, the column will reach essentially of saturated adsorption of benzoic acid and p-Truelove acid, p-tolarova acid replaces adsorbed benzoic acid and adsorbed. Accordingly, using this phenomenon, if the supply of water and the solution is to stop, causing desorption at the time when adsorbed benzoic acid is completely substituted p-Truelove acid and the ratio of p-Truelove acid to benzoic acid in an adsorption column is much larger than this ratio in the feed liquid, p-tolarova acid can be selectively extracted.

It was also found that, as in effluent arising from the adsorption column, the content of p-Truelove acid is lowered, it can be reused as water for dissolving crude terephthalic acid or water for flushing high-purity terephthalic acid, the amount of water in this way can be reduced, and the enormous costs required when you want to release it in that VI is e, as it is, can be reduced, leading to cost reduction in the production of high-purity terephthalic acid.

That is, the essence of this invention lies in the following aspects (1) through (17).

(1) a Method of production of high-purity terephthalic acid comprising the relevant stages: (a) the stage of the oxidation reaction by the oxidation of p-xylene in explicitation solution, where the presence of catalyst with the formation of terephthalic acid, (b) the stage of obtaining crystals of crude terephthalic acid, where the suspension containing the obtained terephthalic acid, is subjected to separation of the solid phase/liquid to obtain crude crystals of terephthalic acid, (C) stage hydrogenation with the dissolution of the crystals of crude terephthalic acid in water to form an aqueous solution and its hydrogenation, (d) stage of the crystallization of high-purity terephthalic acid by crystallization of terephthalic acid from hydrogenated aqueous solution with formation of a suspension of high-purity terephthalic acid, (e) the stage of obtaining crystals of high-purity terephthalic acid, where the suspension of high-purity terephthalic acid is subjected to separation of the solid phase/liquid with obtaining crystals of high-purity terephthalic acid and a primary mother liquor, and (f) the stage of extraction of the p-Truelove to the slots by removing the p-Truelove acid from the primary mother liquor and fed to the phase oxidation reaction, which differs in that phase extraction p-Truelove acid includes the following relevant stages (I) to (IV):

(I) stage adsorption supplied in the form of the treated fluid, the primary mother liquor or secondary mother liquor obtained by cooling the primary mother liquor and separating the solid phase/liquid, in an adsorption column filled with an adsorbent agent, in which the breakthrough time of the p-Truelove acid is greater than the breakthrough time benzoic acid for adsorption of p-Truelove acid and benzoic acid from the treated liquid by adsorbing agent,

(II) stage stop feed stop feed of treated liquid in the adsorption column at some point in time, exceeding the breakthrough time benzoic acid,

(III) the stage of desorption filing Stripping agent in the adsorption column for desorption of adsorbed p-Truelove acid and

(IV) the stage of the circulation of feed p-Truelove acid contained in desorbers agent, resulting from the adsorption column, the stage of the oxidation reaction.

(2) a Method of production of high-purity terephthalic acid as defined above in paragraph (1), which is characterized by the additional inclusion of the following respective steps (g) and (h):

(g) stage of washing and drying Crist is low high-purity terephthalic acid by washing the crystals of high-purity terephthalic acid with water and then drying to obtain a product of high-purity terephthalic acid and

(h) stage circulation of sewage washing with wastewater reuse washing step of washing and drying of crystals of high-purity terephthalic acid as water for dissolving crystals of crude terephthalic acid at the stage of hydrogenation (C).

(3) a Method of production of high-purity terephthalic acid as set out above in paragraphs (1) or (2), which is characterized by the additional inclusion of the following stage (i):

(i) stage circulation effluent with repeated use, at least part effluent of the adsorption column phase adsorption (I) as water to dissolve the crystals of crude terephthalic acid at the stage of hydrogenation (C).

(4) a Method of production of high-purity terephthalic acid as defined above in paragraph (2), which is characterized by the additional inclusion of the next stage (ii):

(ii) the stage of circulation effluent with repeated use, at least part effluent of the adsorption column phase adsorption (I) as the water for washing the crystals of high-purity terephthalic acid at the stage of washing crystals of high-purity terephthalic acid (g).

(5) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (4), which is characterized by the adjustment of the quantity effluent that is reused on the Tadei circulation effluent (i) or (ii), so that the concentration of benzoic acid in primary uterine solution at the stage of obtaining crystals of high-purity terephthalic acid (e) does not exceed 3000 hours/million

(6) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (5), which is characterized by the implementation of the crystallization of terephthalic acid at the stage of the crystallization of high-purity terephthalic acid (d) by evaporation of water from the aqueous solution to reduce the temperature of the aqueous solution, obtained by condensation of the water vapor and the flow of the condensate in the quality of the processed liquid in the adsorption column at the stage of adsorption (I).

(7) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (6), which is characterized by stopping the supply of treated liquid in the adsorption column at the stage stop feeding (II) at the time when the concentration of benzoic acid in affluence of adsorption columns will reach at least 50% of the concentration of benzoic acid in the treated fluid.

(8) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (6), which is characterized by stopping the supply of treated liquid in the adsorption column at the stage stop feeding (II) on or after the mod is enta time when the concentration of benzoic acid in affluence of adsorption columns will be equal to the concentration of benzoic acid in the treated fluid.

(9) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (8), which is characterized by stopping the supply of treated liquid in the adsorption column at the stage stop feeding (II) before the concentration of the p-Truelove acid in effluent of the adsorption column reaches 50% of the concentration of the p-Truelove acid in the treated fluid.

(10) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (8), which is characterized by stopping the supply of treated liquid in the adsorption column at the stage stop feeding (II) before the concentration of the p-Truelove acid in affluence of adsorption columns will reach 20% of the concentration of the p-Truelove acid in the treated fluid.

(11) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (10), which is characterized by the fact that at the stage of adsorption (I) ensure the presence of a plurality of adsorption columns filled with adsorbing agent, in which the breakthrough time of the p-Truelove acid is greater than the breakthrough time benzoic acid, and the corresponding adsorption number is nny designed to repeat the adsorption - desorption - regeneration, the primary mother liquor or secondary mother liquor obtained by the action on the primary mother liquor cooling to separate the solid phase/liquid is supplied to the first adsorption column, and p-tolarova acid and benzoic acid in the treated liquid are adsorbed by the adsorbing agent (however, the effluent of the first adsorption column logs out of the way of adsorption at a time when p-tolarova acid does not enter this effluent); the fact that at the stage stop feeding (II), when p-tolarova acid in effluent from the first adsorption column reaches a given concentration, the flow of the treated fluid in the first adsorption column is stopped and the supply of the treated fluid switch from the first adsorption column to the second adsorption column; the fact that at the stage of desorption (III) deformirujuschij agent moves in the first adsorption column for desorption of adsorbed p-Truelove acid; and at the stage of circulation (IV) p-tolarova acid contained in desorbers agent arising from the first adsorption column, is fed to the stage of the oxidation reaction.

(12) a Method of production of high-purity terephthalic acid as defined above in paragraph (11), which is more under the whose of water in the first adsorption column after passing the stage of desorption (III), to be eluted absorbed deformirujuschij agent, and use the first adsorption column as the adsorption column at the stage of adsorption (I).

(13) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (12), which differs in that deformirujuschij agent is an acetic acid, methyl acetate or a mixture.

(14) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (13), which differs in that the adsorbing agent is a porous copolymer moulinrouge compounds and polyvinyl compounds.

(15) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (13), which differs in that the adsorbing agent is a porous copolymer containing styrene and divinylbenzene as the main components.

(16) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (15), which is characterized by water flow or secondary mother liquor in the adsorption column, where the finished stage desorption (III)desorption of adsorbed Stripping solution.

(17) a Method of production of high-purity terephthalic acid as defined above in any of paragraphs (1) to (16), to which that differs what the adsorption column phase adsorption (I) represented by a set of adsorption columns arranged in series; the fact that the requirement stage stop feeding (II) applies to the first column of the adsorption columns arranged in series; the fact that after stopping the feed to the first column of the processed solution is fed to the second column of adsorption columns arranged in series; and the second column is used as the first column.

The advantages of THIS INVENTION

According to this invention, since the p-tolarova acid in the wastewater, which up to the present time, release, selectively extracted and used as source material for terephthalic acid, it is possible to increase the yield of terephthalic acid. Also, the extraction of the p-Truelove acid from the wastewater as the concentration of organic substances in wastewater can be reduced, it is possible to reduce costs required for wastewater treatment.

BRIEF DESCRIPTION of DRAWINGS

Figure 1 is a block diagram showing a variant of the method of obtaining high-purity terephthalic acid according to this invention.

Figure 2 is a graph showing the concentration of p-Truelove acid and benzoic acid in the liquid supplied to adsorbtion the th column, and affluence in example 1.

Figure 3 is a graph showing the concentration of p-Truelove acid and benzoic acid in desorbers agent, resulting from the adsorption column in example 1.

Figure 4 is a graph showing the concentration of acetic acid in affluence in the regeneration of the adsorption column in example 1.

Figure 5 is a graph showing the concentration of p-Truelove acid and benzoic acid in the liquid supplied to the adsorption column, and affluence in example 2.

6 is a graph showing the concentration of p-Truelove acid and benzoic acid in desorbers agent, resulting from the adsorption column in example 2.

DESCRIPTION of the REFERENCE POSITIONS AND CHARACTERS

1: Phase oxidation reactions

2: Stage crystallization

3: the Stage of obtaining crystals of crude terephthalic acid

4: Stage drying in the stage of obtaining crystals of crude terephthalic acid

5: Phase dehydration of acetic acid

6: the Stage of formation of a suspension of crystals of crude terephthalic acid by using water and then dissolving

7: Phase hydrogenation

8: Phase crystallization of high-purity terephthalic acid

9: Stage of obtaining crystals of high-purity terephthalic acid

10: the Washing of the crystals wysokosci is the terephthalic acid

11: Drying crystals of high-purity terephthalic acid

12: Crystallization and separation of the primary mother liquor

13: Adsorption column

14: Condensate

15: Crystals of high-purity terephthalic acid

16: Primary mother liquor

17: Secondary crystals

18: Secondary mother liquor

19: Effluent from the adsorption column at the flow of the treated fluid in the adsorption column

20: Deformirujuschij agent, resulting from the adsorption column

21: recycled water resulting from the adsorption column

22: reuse effluent solvent in water

23: reuse effluent in the wash water

24: Re-use of wastewater leaching dissolved in the solution.

The BEST embodiments of the present INVENTION

The invention is described further with reference to figure 1.

(a) Phase oxidation reaction:

p-Xylene is a liquid phase oxidized by molecular oxygen in explicitation solvent in the presence of a catalyst with the formation of terephthalic acid (1). This stage is well known; and as a catalyst are catalysts that to the present time known as suitable for use in this reaction, and specific examples include compounds of heavy the x metals such as compounds of cobalt, manganese compounds, iron compounds and compounds of chromium, and bromine compounds. They are present in a dissolved state in the reaction system. Among them, combinations of compounds of cobalt or manganese compounds and bromine compounds are preferred. In this case, these compounds are usually applied in such a way that the cobalt atoms is from 10 to 5000 hours/million atoms of manganese range from 10 to 5000 hours/million and bromine atoms range from 10 to 10000 hours/million relative to the solvent.

Usually mixed gas of inert gas and oxygen is used as the molecular oxygen, and, for example, air or oxygen-enriched air are suitable. The molar ratio of molecular oxygen to p-xylene fed to the reactor, usually from 3 to 20 and preferably from 2 to 4.

The ratio of p-xylene to the acetic acid fed to the reactor, usually from 1 to 50% by weight. The concentration of water in the reaction system is usually from 5 to 20% by weight and preferably from 5 to 15% by mass.

The temperature of the oxidation reaction is usually from 160 to 260C and preferably from 170 to 210C.; the pressure is sufficiently represents the pressure at which the reaction system is able to maintain the liquid phase at the reaction temperature or more, and usually is about is from 0.5 to 5 MPa, and preferably from 1 to 1 MPa; and the residence time is usually from 10 to 200 minutes. Although usually use one reactor or two or more reactors can also be combined in series and used.

(b) the Stage of obtaining crystals of crude terephthalic acid:

As terephthalic acid is poorly soluble in acetic acid as solvent, terephthalic acid, formed at the stage of the oxidation reaction, usually precipitates as crystals, forming a suspension. However, there is a possibility that the terephthalic acid is dissolved depending on the amount of the solvent, the reaction temperature and pressure. In this case, terephthalic acid precipitated, providing phase crystallization (2) cooling the reaction solution to a temperature from 160C to 260C and a pressure of from 0.5 to 5 MPa to a temperature of from 90 to 160C and a pressure from 0 to 0.2 MPa or similar, getting the suspension. This suspension is subjected to separation of the solid phase/liquid (3)to give crude crystals of terephthalic acid (hereinafter sometimes referred to as "STC"). Although the suspension of terephthalic acid produced during the oxidation reaction, is under pressure, it can be subjected to separation of the solid phase/liquid in this state or can be subjected to separation of the solid phase/liquid after discharge pressure for cooling or p is such. As a way of separating the solid phase/liquid is applicable to any method capable of separating the crystals and mother liquor from each other, and examples of such method include filtration and centrifugation.

Mentioned here, the pressure for cooling means that by introducing a slurry of terephthalic acid in the crystallization tank supported at a pressure lower than the pressure of the suspension of terephthalic acid, obtained in stage oxidation reaction, and then reset the pressure, the temperature of the suspension is reduced due to the expansion and evaporation of the solvent.

If desired, the thus obtained crude crystals of terephthalic acid is washed and dried at a temperature of from 100 to 200C (4).

On the other hand, the mother liquor from which the separated crystals of crude terephthalic acid, usually divided into acetic acid and water by distillation, especially azeotropic distillation in the distillation column with reflux a number from 0.2 to 10 and the number of theoretical plates from 25 to 125 (phase dehydration of acetic acid 5). Although the extracted acetic acid is returned to the step oxidation reaction, it can also be used as a Stripping agent to the stage of extraction of the p-Truelove acid. As this mother liquor contains methyl acetate, obrazumit is by heterogeneous reactions of acetic acid, it is preferable to separate and extract it by distillation. The extracted acetate can be used as a Stripping agent phase extraction p-Truelove acid.

(C) stage hydrogenation:

In crystals of crude terephthalic acid obtained at the stage of obtaining crystals of crude terephthalic acid, 4-carboxybenzene (sometimes referred to here as "CBA"), as an intermediate compound oxidation, is contained as an impurity. As CBA causes staining of terephthalic acid, it must be removed. At this stage CBA turns into p-Truelove acid by hydrogenation. Since p-tolarova acid is more soluble in water than terephthalic acid, terephthalic acid and p-tolarova acid can be easily separated using the separation of solid/liquid.

At the stage of hydrogenation of the crude crystals of terephthalic acid is heated together with water, completely dissolving terephthalic acid in water (6); and CBA then restore in p-Truelove acid through reaction with hydrogen in the presence of a hydrogenation catalyst (7).

Such hydrogenation is well known; and the catalysts of the metal of groups 8 to 10, for example, ruthenium, rhodium, palladium, platinum and osmium, applicable as a catalyst for hydrogenation and usually in the form of natvig the CSOs layer, being supported on a carrier such as activated carbon. Among them, palladium deposited on activated carbon, is preferred.

The crystals of the crude terephthalic acid is dissolved in a ratio of usually from 1 to 80 parts by weight and preferably from 15 to 65 parts by weight to 100 parts water by weight. The temperature of hydrogenation is usually from 260 to 320C. and preferably from 270 to 300C; and the partial pressure of hydrogen is generally from 0.5 to 20 kg/cm2(man.).

(d) stage of the crystallization of high-purity terephthalic acid:

As CBA in aqueous solution is restored to water-soluble p-Truelove acid with stage hydrogenation, using crystallization crystals of terephthalic acid from this solution obtain crystals of high-purity terephthalic acid-free p-Truelove acid.

As a method of crystallization (8) usually apply the pressure to the cooling system, which relieve pressure for solvent evaporation. Usually from 2 to 6 tanks of crystallization are connected in series, and manual pressure is released, causing crystallization. Usually pressure from 6.0 to 12 MPa to relieve pressure from 0.1 to 1.0 MPa by means of from 2 to 6 stages. The final crystallization temperature is usually 100C. or more and preferably from 150 is about 160C. Water vapor released from Chan crystallization, usually cool and return condensate (14). Incoming p-tolarova acid is often contained in the condensate. Thus, it is preferable to apply this condensate as liquid to be processed on the stage of adsorption (I), as described below, removing p-Truelove acid.

(e) the stage of obtaining crystals of high-purity terephthalic acid:

The suspension of high-purity terephthalic acid produced during crystallization is subjected to separation of solid/liquid (9), obtaining crystals of high-purity terephthalic acid (hereinafter sometimes referred to as "CTK") (15) and a primary mother liquor (16). As the method of separation of solid/liquid apply any method capable of separating the crystals and mother liquor from each other, and examples of the method include filtration and centrifugation.

Since p-tolarova acid soluble in water, it remains in the primary fallopian solution. For this reason, the content of p-Truelove acid in crystals of high-purity terephthalic acid exceptionally low. When crystals of high-purity terephthalic acid, separated from the primary mother liquor, washed with water (10) and then dried at a temperature of from 100 to 200C (11), the result is a product of high-purity terephthalic acid. Stock the e water (24) flushing can be used as water for dissolving crystals of crude terephthalic acid at the stage of hydrogenation.

On the other hand, water-soluble by-products of the reaction such as p-tolarova acid and benzoic acid, and organic substances such as terephthalic acid, which is not settled, are contained in primary uterine solution.

When reusing effluent of the adsorption column as a solvent of water or wash water preferably, the amount for re-use was regulated, thereby regulating the concentration of benzoic acid in primary fallopian solution at usually no more than 3000 hours per million) and preferably not more than 1500 hours/million When the concentration of benzoic acid in primary fallopian solution is not too high, you can save a concentration of benzoic acid in the product of high-purity terephthalic acid obtained by the usual washing and drying not more than 50 hours/million and, particularly, not more than 25 hours/million even if you reuse effluent containing benzoic acid. High-purity terephthalic acid having a concentration of benzoic acid within the above range, are able to maintain physical properties of high-purity terephthalic acid, such that the degree of polymerization of the polyester obtained by the use of this high-purity terephthalic acid, reaches a given value, and less painted on ifir can be obtained. When the concentration of benzoic acid in primary uterine solution is too high to obtain high-purity terephthalic acid having a content of benzoic acid within the above range, the washing should be strengthened, the amount of water used for washing, increases, and the cost required for the production of high-purity terephthalic acid, increase.

(f) stage extraction p-Truelove acid:

In this invention the p-Truelove acid in primary fallopian solution is separated from benzoic acid and extract with absorbent agent (13). Primary mother liquor contains typically from about 500 to 5000 h/m p-Truelove acid, usually about 50 to 500 hours/million benzoic acid and usually from about 1000 to 5000 hours/million terephthalic acid, the content of which, however, varies with the temperature of crystallization of high-purity terephthalic acid.

Although the primary mother liquor can be granted for the adsorption treatment, as it is, it is preferable to cool it to precipitate part of the dissolved p-Truelove acid, terephthalic acid and other organic substances with subsequent separation of the solid/liquid by filtration or other means, separating the secondary crystals (17) and secondary uterine Rast is PR (18) from each other; and to send the extracted secondary mother liquor for the adsorption process. The temperature of the primary cooling the mother liquor is usually from 20 to 100C. and preferably from 40 to 80C, and a secondary mother liquor is usually subjected to an adsorption treatment at a temperature falling within this range. Thus, even adsorbing agent, which upon contact with the primary mother liquor with a high temperature may deteriorate, can be safely used. In the case of secondary stock solution, as the concentration of the p-Truelove acid is reduced, a larger amount of the mother liquor may be supplied to the adsorption column until the operation is complete adsorption. When the primary mother liquor is cooled to room temperature, the secondary mother liquor contains typically from about 100 to 1000 h/m p-Truelove acid, usually from about 100 to 1000 hours/million benzoic acid and usually from about 1 to 500 hours/million terephthalic acid. Because the sludge produced by the separation of solid/liquid, formed mainly of p-Truelove acid and terephthalic acid, it is possible to apply for phase oxidation reactions (17).

As described above, since the condensate (14), obtained by the condensation of water vapor occurring during crystallization, can phase cu is stylizacji high-purity terephthalic acid to contain the incoming p-Truelove acid, this condensate can also be fed to the adsorption column with a primary mother liquor or secondary mother liquor. In this case, since the condensate has a high temperature, it is preferable to mix it with the primary mother liquor. The condensate contains typically from about 100 to 1000 h/m p-Truelove acid, usually about from 10 to 500 hours/million benzoic acid and typically from about 500 to 3000 hours/million terephthalic acid.

(I) stage of adsorption and (II) stage stop feed:

In this invention a mixture of primary mother liquor or secondary mother liquor, or both, and containing n-Truelove acid condensate (this mixture will hereinafter be called "processed fluid) supplied to the adsorption column (13)filled with adsorbing agent, where the breakthrough time of the p-Truelove acid is greater than the breakthrough time benzoic acid, and is forced to flow down inside the column. When applying a liquid containing the adsorbed substance in the adsorption column filled with an adsorbent agent, the point in time at which the adsorbed substance is detected in effluent of the adsorption columns, referred to as the breakthrough point adsorbed substances; and the time from the beginning of the fluid containing the adsorbed substance in the adsorption column before reaching t is his breakthrough substances adsorbed is called the breakthrough time adsorbed substances.

As benzoic acid and p-tolarova acid in the treated fluid adsorbed in the adsorbing agent with exit adsorption column (19) is derived liquid that does not contain them. However, when the flow of the treated fluid continues, it reaches the point of breakthrough benzoic acid, resulting benzoic acid appears in the fluid flowing from the outlet of the adsorption column. Here, when a solution containing p-Truelove acid and benzoic acid, is treated with adsorption columns, the point at which benzoic acid is found in affluence, referred to as the breakthrough point of benzoic acid, and the time required from the start of the fluid before reaching the point of breakthrough, called the breakthrough time. When the flow of the treated fluid in the adsorption column continues, exceeding the breakthrough time of benzoic acid, the concentration of benzoic acid in the liquid flowing from the output gradually increases and after some time becomes higher than the concentration of benzoic acid in the treated fluid. This shows that p-tolarova acid in the treated fluid replaces benzoic acid adsorbed on the adsorbing agent, and is adsorbed.

When the flow of the treated fluid continues further, it reaches the point of breakthrough is-Truelove acid, and p-tolarova acid also appears in the fluid flowing from the outlet of the column. Here, when a solution containing p-Truelove acid and benzoic acid, is treated with adsorption columns, the point at which p-tolarova acid found in affluence, referred to as the breakthrough point p-Truelove acid, and the time required from the start of the fluid before reaching the point of breakthrough, called the breakthrough time. When the flow of the treated fluid in the adsorption column continues, exceeding the breakthrough time of the p-Truelove acid, the concentration of p-Truelove acid in the liquid gradually increases and becomes in the end is equal to the concentration in the treated fluid. Before reaching the point of breakthrough benzoic acid (breakthrough time benzoic acid) ratio p-Truelove acid to benzoic acid in an adsorption column is equal to the ratio of the p-Truelove acid to benzoic acid in the treated fluid; however, when the time exceeds the breakthrough point, this ratio gradually increases, and at some point in time at which the concentration of benzoic acid and p-Truelove acid in affluence meet their concentrations in the treated fluid, namely the saturation point, this ratio becomes maximum. Accordingly, when the flow of the treated fluid is adsorption column stop at a random point in time after passing through the breakthrough point of benzoic acid (breakthrough time benzoic acid) before reaching the saturation point and instead serves deformirujuschij agent for desorption of adsorbed benzoic acid and p-Truelove acid, can be extracted p-Truelove acid related p-Truelove acid to benzoic acid is higher than this ratio in the treated fluid.

Usually the flow of the treated fluid is stopped after the concentration of benzoic acid in effluent reaches at least 10% and especially at least 20% of its concentration in the treated fluid. It is generally preferable when the flow is stopped after the concentration of benzoic acid in effluent reaches 50% or more, particularly 100% or more from its concentration in the treated fluid. When the flow of the treated fluid is stopped after n-tolarova acid appears in affluence, you can extract p-Truelove acid having a lower content of benzoic acid. When the concentration of the p-Truelove acid in effluent at the time of stopping supply is high, although the concentration of benzoic acid in the extracted p-Truelove acid decreases, the amount of recovered p-Truelove acid decreases the reverse way. Although the point in time at which the flow of the treated fluid must be stopped, determine, taking into account the extraction of p-Truelove acid and accessible amount of benzoic acid is you, contained in the p-Truelove acid, filing usually stop before the concentration of the p-Truelove acid in effluent reaches 90% and preferably 50% of the p-Truelove acid in the treated fluid. It is generally preferable when the flow is stopped at the time when it reaches at least 80% and especially at least 90% of the time overshoot p-Truelove acid and during the time from the point of breakthrough p-Truelove acid to achieve a concentration of the p-Truelove acid in effluent 25%, preferably 20%, and especially 10% of the concentration in the treated fluid.

Although arbitrary adsorbing agent may be used, if it is a porous adsorbing agent, in which the breakthrough time of the p-Truelove acid is greater than the breakthrough time benzoic acid, commonly used in organic synthetic adsorbing agent. For example, synthetic adsorbing agents based on a styrene-divinylbenzene, such as SEPABEADS SP825, SP850 and SP207 (SEPABEADS is a registered trademark of Mitsubishi Chemical Coporation), and AMBERLITE XAD-4 and XAD-16 (AMBERLITE is a registered trademark of Rohm and Haas Company), and acrylic synthetic adsorbing agents such as DIAION HP2MG (DIAION is a registered trademark of Mitsubishi Chemical Coporation) and AMBERLITE XAD-4 and XAD-8, which may be used. Preferably used non-polar organic synthetic adsorbing agents, especially synthetic adsorbing agents formed of a porous copolymer moulinrouge compounds and polyvinyl compounds, primarily synthetic adsorbing agents based on a styrene-divinylbenzene. So as benzoic acid, and p-tolarova acid contain the benzene ring, they are easily adsorbed on synthetic agent based on a styrene-divinylbenzene, and the adsorption capacity of p-Truelove acid is usually higher than the adsorption capacity of benzoic acid.

The specific surface area of the adsorbing agent is usually from 400 to 1500 m2/g and preferably from 600 to 1000 m2/g; pore volume is usually from 0.5 to 3 ml/g and preferably from 1.0 to 2.0 ml/g; and a pore size typically ranges from 10 to 1000 angstroms, and preferably from 50 to 500 angstroms. Adsorbing agent is filled so that the height of the layer of filling is usually approximately from 1.5 to 4.0 m Usually, when the height of the layer of filling is too small, the effectiveness of adsorbing agent is reduced, the value of which, however, varies with time when the need to stop the flow of the treated fluid. The feed rate of the treated fluid in the adsorption column is usually equally is from 0.5 to 30 m/h for LV and is usually from 0.5 to 20 h -1for SV, respectively.

(III) the stage of desorption:

After stopping the supply of treated liquid in the adsorption column deformirujuschij agent supplied to the adsorption column (not shown), desorber adsorbed benzoic acid and p-Truelove acid. After stopping the supply of the treated fluid deformirujuschij agent may be supplied after the supply of water and the release of treated water in an adsorption column.

Acetic acid, methyl acetate or a mixture thereof can be used as a Stripping agent. As acetic acid or methyl acetate is extracted from the steam generated in the system, or the mother liquor of the crystals of crude terephthalic acid in a period of time from the stage of the oxidation reaction to the stage of obtaining crystals of crude terephthalic acid, they can be used.

The feed rate of Stripping agent is usually from 0.5 to 30 m/h for LV and usually from 0.5 to 20 h-1for SV, respectively. The temperature of the Stripping agent may be arbitrarily selected in the range from the freezing point or higher and not higher than the boiling point of the Stripping agent; and, for example, when deformirujuschij agent is acetic acid, the temperature from room temperature to 80C. is preferred. Although the ratio of p-Truelove acid and benzoic acid is you solution Stripping agent, containing p-Truelove acid and benzoic acid, resulting from the adsorption column, varies with the proportion of p-Truelove acid and benzoic acid in the treated liquid and the time when to stop the flow of the treated fluid, preferably, when the ratio of benzoic acid to p-Truelove acid not more than 35 mass%.

(IV) the stage of circulation:

p-Tolarova acid in desorbers agent (20), resulting from the adsorption columns, usually p-tolarova acid and benzoic acid, serves on the stage of the oxidation reaction. Simply deriving deformirujuschij agent can be fed to the stage of the oxidation reaction in the same condition as it is. When acetic acid is used as the Stripping agent, preferably, when deriving deformirujuschij agent comes into contact with the exhaust gas of the reaction, gas phase oxidation reaction, and then fed to the stage of the oxidation reaction. Although the acetate released from acetic acid as the reaction solvent, contained in the exhaust gas of the reaction, as it is absorbed, acetic acid, and is returned to the system of the oxidation reaction, it is possible to suppress the reaction of acetic acid to acetate.

Then, water is supplied to the adsorption column after passing the stage of desorption with the release of desorbers what about the agent in the column, regenerating the adsorption column. The rate of water flow is generally from 0.5 to 30 m/h for LV and usually from 0.5 to 20 h-1for SV, respectively. Although the temperature of the feedwater is arbitrary, it is usually from room temperature to 80C. So as deformirujuschij agent contained in the regenerating water (21), resulting from the adsorption columns, for example, a liquid containing 50% or more of acetic acid in the beginning of regeneration, is fed into the system of the oxidation reaction; and regenerating the water in subsequent stages served as dephlegmation liquid distillation, etc. for distillation at the stage of dehydration of acetic acid and distilled with removing the Stripping agent and its reuse. This distillation can be carried out with an aqueous solution of acetic acid generated in the system, in addition to the single distillation. Here the secondary mother liquor can also be used as water supplied to the adsorption column.

Although the invention can be implemented by using a single adsorption column at the stage of adsorption (I), you can create the opportunity for adsorption treatment continuously as a whole by providing a set of adsorption columns filled with adsorbing agent, in the cat the rum the breakthrough time of the p-Truelove acid is greater than the breakthrough time benzoic acid, and switching of the adsorption columns, which served the processed liquid. Each of the adsorption columns is designed to repeat the adsorption - desorption - regeneration. "The primary mother liquor or secondary mother liquor obtained by the action on the primary mother liquor cooling to separate the solid phase/liquid", served as the treated fluid in the first adsorption column, and p-tolarova acid and benzoic acid in the treated fluid adsorbed in the adsorbing agent. At this time, although the effluent of the first adsorption column is produced in the system of the adsorption process during the time when p-tolarova acid does not come in the effluent, the effluent can be reused as water for flushing high-purity terephthalic acid at the stage of washing crystals of high-purity terephthalic acid (g) or to dissolve the crystals of crude terephthalic acid at the stage of hydrogenation (C). Then, at the stage stop feeding (II), when p-tolarova acid in effluent from the first adsorption column reaches a predetermined concentration, by stopping the supply of the treated fluid in the first adsorption column and switch the supply of the treated fluid from the first adsorption column to the second also blonay column removing the p-Truelove acid in the treated liquid is not reduced. Accordingly, in this case, at the time when the ratio of the p-Truelove acid to benzoic acid in the first adsorption column will be the most high, the flow of the treated fluid in the first adsorption column can be stopped. At the stage of desorption (III) deformirujuschij agent moves in the first adsorption column, desorber adsorbed p-Truelove acid; and at the stage of circulation (IV) p-tolarova acid contained in desorbers agent arising from the first adsorption column, is fed to the stage of the oxidation reaction.

In this invention a multiple (usually two) of the adsorption columns may be placed in series, and in this case, the requirements (I) to (IV) in the invention of this application can be applied and implemented in the first column of the adsorption columns arranged in series. After stopping the supply of the treated fluid in the first column by this direction of the treated fluid to the second column of adsorption columns arranged in series, this second column can be used as the first column. During use the second column as the first column to the new target column, in which complete regeneration (for example, if the location of two columns in series, a new second column), can be provide the young.

(g) stage washing and drying the crystals of high-purity terephthalic acid:

By washing the crystals of high-purity terephthalic acid, separated from the primary mother liquor, water (10) and then drying them (11) receive the product of high-purity terephthalic acid. Washing of the crystals of high-purity terephthalic acid can be performed using the method of supplying water in an apparatus for separating solid/liquid or by using a method of leaching a slurry of crystals of high-purity terephthalic acid with water followed by separation of solid/liquid. Here as a device separation solid/liquid you can use the same apparatus as used in the above-described operations division solid/liquid. As one preferred example of the apparatus for the separation of solid/liquid you can list a centrifuge with mesh dividers and the like.

When flushing is performed by supplying water into the device separation solid/liquid, the temperature of the water used for washing, usually equal to the temperature of the suspension of high-purity terephthalic acid at the stage of crystallization or higher and not higher than the boiling point at the operating pressure, preferably from 100 to 180C. and more preferably from 140 to 170C. In the case of prom is Cai suspension water temperature, which is used for washing, is usually from 30 to 180C. Although the amount of water used for the washing, varies with the quantity of impurities contained in high-purity terephthalic acid tolerant of impurities for a product of high purity terephthalic acid by the method of leaching and the like, water is usually used in amounts of from about 0.1 to 2 tons per ton of crystals of high-purity terephthalic acid. For drying use drying apparatus, such as a tumble dryer with a steam pipe and a drying apparatus with a fluidized bed, and the drying temperature is usually from 80 to 180C.

(h) stage wastewater circulation washing:

At least part of the sewage washing on the stage of washing and drying of the crystals of high-purity terephthalic acid is reused as water for dissolving crystals of crude terephthalic acid at the stage of hydrogenation (C) (24). Preferably, the entire quantity of wastewater leaching is used as a solvent water.

When the supply of treated water in the adsorption column as liquid, resulting from the adsorption column (19)essentially does not contain organic substances before reaching the point of breakthrough benzoic acid (time overshoot benzoic acid), among effluents after the point of breakthrough benzoin the th acid part or all and preferably part effluent having a low concentration of benzoic acid may be used as solvent of water (22) for crystals of crude terephthalic acid at the stage of hydrogenation or solvent water (23) for crystals of high-purity terephthalic acid after separation of solid/liquid at the stage of obtaining crystals of high-purity terephthalic acid (e). In the case of use as wash water extraction stages crystals of high-purity terephthalic acid waste water rinse is usually used as a solvent of water to crude terephthalic acid at the stage of hydrogenation (24).

Thus, in the case of reuse effluent of the adsorption column as a solvent of water or the washing of water by regulating the amount for reuse so as to have a concentration of benzoic acid in primary uterine solution is usually not more than 3000 hours per million) and preferably not more than 1500 hours/million, you can save a concentration of benzoic acid in the resulting product of high-purity terephthalic acid is not more than 60 hours/million and especially not more than 30 hours/million; degree of polymerization of the polyester to be obtained from using this product reaches the preset value; and less colored polyester can bytevalue.

Among affluent adsorption of one that is not used in the system is produced. However, in this liquid contains heavy metals originating from the catalyst phase oxidation reaction, and when it is released into the environment, there is a possibility of their harmful effects on the environment. Accordingly, it is preferable to release the liquid, after removal of heavy metals through their treatment of ion-exchange resins. Usually strongly acidic ion-exchange resin may be used as ion-exchange resin. Heavy metals adsorbed on ion-exchange resin can be reused as a catalyst for the reaction of oxidation by desorption of acid.

This invention below specifically described with reference to examples, but it should be understood that this invention is not limited to these examples.

EXAMPLE 1

18,8 g (33 ml) of synthetic adsorbing agent SEPABEADS SP825L, manufactured by Mitsubishi Chemical Corporation, was weighed in a glass and turned into a slurry by using methanol; and after thorough degassing the suspension was poured into a glass column having an inner diameter of 17.8 mm, the Suspension is washed with clean water and proved using gas chromatography that methanol is not detected.

An aqueous solution containing p-Truelove to the slot and benzoic acid, continuously fed into the column at 388 ml/h, effecting the adsorption treatment. Feeding was done at SV=10 h-1and LV=1.4 m/H. the concentration of p-Truelove acid and benzoic acid in the feed liquid and effluent periodically measured. The results are shown in figure 2.

Then acetic acid containing 300 h/m p-Truelove acid and 7% water, served as a Stripping agent at SV=10 h-1in the above-mentioned column. The concentration of p-Truelove acid and benzoic acid in desorbers agent arising from the columns were periodically measured. The results are shown in figure 3.

Also, the water having room temperature, was applied at SV=5 h-1in the column desorbed acetic acid, to regenerate the column until the concentration of acetic acid in water were periodically measured. The results are shown in figure 4.

EXAMPLE 2

The slurry of crude terephthalic acid obtained by oxidation of p-xylene with air in explicitation solvent in the presence of a catalyst obtained from compounds of cobalt, manganese compounds and bromovalerate were subjected to separation of solid/liquid, obtaining crystals of crude terephthalic acid. The aqueous slurry containing the crystals of crude terephthalic acid in a ratio of 30% by weight, was heated, getting an aqueous solution, which is then guy who has demonstrated at 290C and 8.7 MPa in the presence of a catalyst, formed from palladium deposited on activated carbon.

Hydrogenated aqueous solution was subjected to pressure relief for step cooling by using a crystallization tank, with five tanks crystallization connected with each other successively, and finally cooled to 155C, obtaining a suspension of high-purity terephthalic acid. This suspension was subjected to separation of solid/liquid, obtaining crystals of high-purity terephthalic acid and a primary mother liquor. Crystals of high-purity terephthalic acid is washed with water in an amount of 1.5 tonnes per tonne of high-purity terephthalic acid and then dried at 140C, obtaining a product of high purity terephthalic acid having a concentration of benzoic acid 5 hours/million Primary mother liquor was subjected to discharge pressure for cooling to 80C in the tank vent for cooling, precipitating crystals and receiving a suspension. It was shared with by using a filter, receiving the secondary crystals and a secondary mother liquor. Secondary mother liquor has a concentration of benzoic acid 300 h/m and the concentration of p-Truelove acid 700 hours/million

13 kg (19 l) synthetic adsorbing agent SEPABEADS SP207, manufactured by Mitsubishi Chemical Corporation, was loaded into a column of stainless steel having an inner diameter of 260 mm, was added water and carefully is performed on degassing, finally getting the adsorption column. Secondary mother liquor was continuously applied in this adsorption column at SV=10 h-1and LV=3.6 m/h Concentration of benzoic acid and p-Truelove acid in the liquid supplied to the adsorption column, and effluent of the adsorption columns is shown in figure 5.

Acetic acid containing 300 h/m p-Truelove acid and 7% of water, was applied at SV=2 h-1in the adsorption column having adsorbed therein benzoic acid and p-Truelove acid, desorber adsorbed benzoic acid and p-Truelove acid. The results are shown in Fig.6.

From this experiment indicated that when applying an aqueous solution containing benzoic acid, and p-Truelove acid, in the adsorption column filled with the data of porous adsorbing agent, evaluating the condition of leakage of these compounds in effluent arising from the adsorption column, first all of benzoic acid and p-tolarova acid are absorbed and, therefore, the liquid not containing any of the two acids, derived from the adsorption column; however, when the flow of an aqueous solution continues, benzoic acid appears in affluence, and the concentration of benzoic acid in effluent gradually increases, and when this the concentration becomes significantly high, p-toluyl the Wai acid first appears in affluence, and its concentration is gradually increased.

This means that the n-tolarova acid stronger adsorption ability on this porous adsorbing agent than benzoic acid, and that after adsorption column reached essentially of saturated adsorption of benzoic acid and p-Truelove acid, p-tolarova acid replaces adsorbed benzoic acid and adsorbed. Accordingly, it is noted that by applying this phenomenon and stop feeding the aqueous solution at the time when adsorbed benzoic acid thoroughly substituted p-Truelove acid and the ratio of p-Truelove acid to benzoic acid in an adsorption column is much larger than this ratio in the feed liquid, p-tolarova acid can be selectively extracted.

Feeding acetic acid, the solvent oxidation reaction, in this adsorption column having adsorbed therein benzoic acid and p-Truelove acid, can be decarbonate adsorbed benzoic acid and p-Truelove acid, and, therefore, terephthalic acid can be preferably obtained by circulating p-Truelove acid, which is used as source material for terephthalic acid at the stage of the oxidation reaction.

EXAMPLE 3

0.5 g with staticheskogo adsorbing agent SEPABEADS SP825, manufactured by Mitsubishi Chemical Corporation, was added to 100 ml of an aqueous solution containing p-Truelove acid at a concentration of 332 hours/million, and the mixture was stirred at room temperature for 15 hours, reaching equilibrium adsorbed p-Truelove acid. The number of p-Truelove acid adsorbed on the adsorbing agent, was 27 mg

This adsorbing agent was removed from the aqueous solution, to which was then added 20 ml of methyl acetate, and this mixture was stirred at room temperature for 6 hours to decarbonate p-Truelove acid. As a result, the number of p-Truelove acid in desorbers agent was 27 mg

This adsorbing agent is then washed with 100 ml of water and then added to 100 ml of an aqueous solution containing p-Truelove acid at a concentration of 332 hours/million, and the mixture was stirred at room temperature for 15 hours, again adsorbing p-Truelove acid. As a result, the number of p-Truelove acid adsorbed on the adsorbing agent, was 23 mg, and it was confirmed that acetate is suitable as a Stripping agent.

EXAMPLE 4

13 kg (19 l) synthetic adsorbing agent SEPABEADS SP207, manufactured by Mitsubishi Chemical Corporation, was loaded into a column of stainless steel having an inner diameter of 260 mm and a volume of 24 l, and this secondary mA the internal solution was applied at SV=10 h -1and LV=3.6 m/h for 10 hours. When the flow stopped, the concentration of p-Truelove acid in effluent was 127 hours/million All effluent from the adsorption column was collected in a tank. As a result, effluent was 1900 l, the concentration of benzoic acid was 222 h/m and the concentration of p-Truelove acid was 12 hours/million

The concentration of benzoic acid contained in the primary mother solution, and the obtained high-purity terephthalic acid, while using thus obtained effluent as part of the washing water for crystals of high-purity terephthalic acid and use of sewage washing for the entire amount of solvent water for high-purity terephthalic acid was calculated by simulation. The results are shown in table 1.

[Table 1]
The liquid fraction, re-used as wash liquid in affluence of adsorption columnsThe concentration of benzoic acid in primary fallopian solution (h/m)The concentration of benzoic acid in the obtained high-purity terephthalic acid (h/m)
Example 1 203126
Example 25049710
Example 37082116
Example 490235347

EXAMPLE 5

To a high-purity terephthalic acid (CTK), manufactured by Mitsubishi Chemical Corporation) was added benzoic acid in an amount corresponding to 0 hours/million, 50 h/m and 100 hours/million, respectively, and added 1,004 parts of ethylene glycol by weight relative to the part of the mass of terephthalic acid, and this mixture was subjected to esterification at 235C for 53 minutes, and then for 45 minutes at 260C, and then polymerisable at 280C for 100 minutes in equipment evaluation polymerization. Value hunter b obtained polyester was measured using meter color contrast, manufactured by Suga Test Instruments Co., Ltd. As a result, the magnitude of hunter b amounted to 1.38, 1,68, and was 1.94, respectively.

Discussion:

Oxidation of p-xylene gives p-Truelove acid. Oxidation of p-Truelove acid gives 4-carboxybenzoyl acid, and oxidation of 4-carboxybenzoyl acid gives terephthal the new acid. For this reason, by applying p-Truelove acid, extracted in examples 1 to 3, at the stage of oxidation is obtained terephthalic acid, and the yield of terephthalic acid may be increased.

Although this invention is described in detail and with reference to specific variations in its implementation, the specialist in the art it will be obvious that various changes and modifications can be made therein without deviating from the essence and scope.

This application is based on Japanese patent application, registered on March 22, 2005 (Japanese patent application No. 2005-082038), and Japanese patent application, registered on March 23, 2005 (Japanese patent application No. 2005-084186), the entire contents of which are incorporated here by reference.

INDUSTRIAL APPLICABILITY

According to this invention, since the p-tolarova acid in the wastewater, which to date has released selectively extracted and used as source material for terephthalic acid, it is possible to increase the yield of terephthalic acid. Also, the extraction of the p-Truelove acid from the wastewater as the concentration of organic substances in wastewater can be reduced, it is possible to reduce costs required for wastewater treatment. Thus, the industrial significance of this invention Zam is final.

1. The method of obtaining high-purity terephthalic acid comprising the relevant stages: (a) phase oxidation reaction, where oxidize p-xylene in acetic acid solution, where the presence of catalyst with the formation of terephthalic acid, (b) the stage of obtaining crystals of crude terephthalic acid, where the suspension containing the precipitate obtained terephthalic acid, is subjected to separation of the solid phase/liquid to obtain crude crystals of terephthalic acid, (C) stage hydrogenation, where dissolved crystals of crude terephthalic acid in water to form an aqueous solution and hydronaut it, (d) stage crystallization high-purity terephthalic acid, which crystallized terephthalic acid from hydrogenated aqueous solution with formation of a suspension of high-purity terephthalic acid, (e) the stage of obtaining crystals of high-purity terephthalic acid, where the suspension of high-purity terephthalic acid is subjected to separation of the solid phase/liquid with obtaining crystals of high-purity terephthalic acid and a primary mother liquor, and (f) the stage of extraction of the p-Truelove acid, which is extracted p-Truelove acid from the primary mother liquor and serve it on stage oxidation reaction, which is characterized by the fact that phase extraction p-Truelove acid includes the next appropriate stage:
(I) stage of adsorption, serving as the treated fluid primary mother liquor or secondary mother liquor obtained by the primary cooling the mother liquor to separate the solid phase/liquid in the adsorption column filled with an adsorbent agent, in which the breakthrough time of the p-Truelove acid is greater than the breakthrough time benzoic acid for adsorption of p-Truelove acid and benzoic acid from the treated liquid by adsorbing agent,
(II) stage stop feeding, stop where the flow of the treated fluid in the adsorption column at some point in time, when the concentration of benzoic acid in affluence of adsorption columns will reach at least 10% of the concentration of benzoic acid in the treated fluid,
(III) the stage of desorption, where deformirujuschij agent representing acetic acid, methyl acetate or a mixture, supplied to the adsorption column for desorption of adsorbed p-Truelove acid and
(IV) the stage of circulation, where p is Truelove acid contained in desorbers agent, resulting from the adsorption column, serves on the stage of the oxidation reaction.

2. The method of obtaining high-purity terephthalic acid according to claim 1, which is characterized by the additional inclusion of the following respective steps:
(g) stage washing is drying crystals of high-purity terephthalic acid, where the washed crystals of high-purity terephthalic acid with water and then dried to obtain a product of high-purity terephthalic acid, and
(h) stage wastewater circulation flushing, where re-use of waste water rinsing stage of the washing and drying of the crystals of high-purity terephthalic acid as water for dissolving crystals of crude terephthalic acid at the stage of hydrogenation (C).

3. The method of obtaining high-purity terephthalic acid according to claim 1, which is characterized by the additional inclusion of the following stages:
(i) the stage of circulation effluent where reuse at least part effluent of the adsorption column phase adsorption (I) as water to dissolve the crystals of crude terephthalic acid at the stage of hydrogenation (C).

4. The method of obtaining high-purity terephthalic acid according to claim 2, which is characterized by the additional inclusion of the following stages:
(i) the stage of circulation effluent where reuse at least part effluent of the adsorption column phase adsorption (I) as water to dissolve the crystals of crude terephthalic acid at the stage of hydrogenation (C).

5. The method of obtaining high-purity terephthalic acid according to claim 2, which is characterized by the additional inclusion of the following stages:
(ii) the stage of circulation effluent, where the repeat is about use, at least part effluent of the adsorption column phase adsorption (I) as the water for washing the crystals of high-purity terephthalic acid at the stage of washing crystals of high-purity terephthalic acid (g).

6. The method of obtaining high-purity terephthalic acid according to claim 3 or 4, which is characterized by the fact that the number effluent re-used at the stage of circulation effluent (i)is adjusted so that the concentration of benzoic acid in primary uterine solution at the stage of obtaining crystals of high-purity terephthalic acid (e) does not exceed 3000 hours/million

7. The method of obtaining high-purity terephthalic acid according to claim 5, characterized in that the number effluent re-used at the stage of circulation effluent (ii)is adjusted so that the concentration of benzoic acid in primary uterine solution at the stage of obtaining crystals of high-purity terephthalic acid (e) does not exceed 3000 hours/million

8. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that the crystallization of terephthalic acid at the stage of the crystallization of high-purity terephthalic acid (d) carry out the evaporation of water from the aqueous solution to reduce the temperature of the aqueous solution, condense obtained water vapor and serves the condensate as the treated fluid is the adsorption column at the stage of adsorption (I).

9. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that stop the flow of treated liquid in the adsorption column at the stage stop feeding (II) at the time when the concentration of benzoic acid in affluence of adsorption columns will reach at least 50% of the concentration of benzoic acid in the treated fluid.

10. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that stop the flow of treated liquid in the adsorption column at the stage stop feeding (II) on or after the point in time when the concentration of benzoic acid in affluence of adsorption columns will be equal to the concentration of benzoic acid in the treated fluid.

11. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that stop the flow of treated liquid in the adsorption column at the stage stop feeding (II) before the concentration of the p-Truelove acid in effluent of the adsorption column reaches 50% of the concentration of the p-Truelove acid in the treated fluid.

12. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that stop the flow of treated liquid in the adsorption column at the stage stop feeding (II) d is also as the concentration of p-Truelove acid in affluence of adsorption columns will reach 20% of the concentration of the p-Truelove acid in the treated fluid.

13. The method of obtaining high-purity terephthalic acid according to claim 1, which is characterized by the fact that at the stage of adsorption (I) ensure the presence of a plurality of adsorption columns filled with adsorbing agent, in which the breakthrough time of the p-Truelove acid is greater than the breakthrough time benzoic acid, and the corresponding adsorption column is designed to repeat the adsorption - desorption - regeneration, the primary mother liquor or secondary mother liquor obtained by the action on the primary mother liquor cooling to separate the solid phase/liquid fed to the first adsorption column, and p-tolarova acid and benzoic acid in the treated fluid adsorbed adsorbing agent; the fact that at the stage stop feeding (II), when p-tolarova acid in effluent from the first adsorption column reaches a predetermined concentration, the flow of the treated fluid in the first adsorption column is stopped and the supply of the treated fluid switch from the first adsorption column to the second adsorption column; the fact that at the stage of desorption (III) deformirujuschij agent fed to the first adsorption column is La desorption of adsorbed p-Truelove acid; and at the stage of circulation (IV) p-Truelove acid contained in desorbers agent arising from the first adsorption column, serves on the stage of the oxidation reaction.

14. The method of obtaining high-purity terephthalic acid according to item 13, which is characterized by the fact that additional water is supplied to the first adsorption column after passing the stage of desorption (III)that eluted absorbed deformirujuschij agent, and use the first adsorption column as the adsorption column at the stage of adsorption (I).

15. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that the adsorbing agent is a porous copolymer moulinrouge compounds and polyvinyl compounds.

16. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that the adsorbing agent is a porous copolymer containing styrene and divinylbenzene as the main components.

17. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that water is supplied or secondary mother liquor in the adsorption column, where the finished stage desorption (III)desorption of adsorbed Stripping solution.

18. The method of obtaining high-purity terephthalic acid according to claim 1, characterized in that the adsorption columns the stage and adsorption (I) represented by a set of adsorption columns, arranged in series; the fact that the requirement stage stop feeding (II) apply to the first column of the adsorption columns arranged in series; the fact that after stopping the feed in the first column of the processed solution serves the second column of adsorption columns arranged in series; and a second column is used as the first column.

19. The method of obtaining high-purity terephthalic acid according to item 13, which differs in that the effluent from the first adsorption column release from the system method of adsorption at a time when p-tolarova acid is not contained in this effluent.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to liquid-phase catalytic oxidation of an aromatic compound and a reactor-type bubble column. A stream of oxidising agent which contains molecular oxygen and a stream of starting material containing the oxidised compound are fed into the reaction zone of the bubble column reactor. As a result of oxidation, a solid-phase product from at least approximately 10 wt % of the oxidised compound is obtained. At least a portion of the reaction medium containing the solid-phase product is taken from the reaction zone through one or more openings lying at a higher level than the inlet zone of at least a portion of the molecular oxygen into the reaction zone. Average gas flow rate per unit cross section of the stream at half the height of the said reaction medium is kept equal to at least approximately 0.3 m/s. The proposed installation has a bubble column reactor with a perforated shell, a reaction medium container and a channel designed for carrying spent reaction medium into the container.

EFFECT: product can be extracted and purified using methods which are cheaper than those which can be used if the acid is obtained via a high-temperature oxidation method.

32 cl, 35 dwg, 7 tbl, 13 ex

FIELD: chemistry.

SUBSTANCE: invention relates to liquid-phase catalytic oxidation of an aromatic compound and to the obtained crude terephthalic acid. Oxidation is carried out in a bubble column reactor which ensures a highly efficient process at relatively low temperature. Particles of the obtained terephthalic acid, which contains approximately less than 100 parts weight/million of 2,6-dicarboxyfluorenone, have transmission factor at 340 nm (%T340) greater than approximately 25%, additionally contains approximately less than 12 parts weight/million of 4,4-dicarboxystilbene and/or contains approximately less than 400 parts weight/million of isophthalic acid. Particles of the obtained terephthalic acid, characterised by average size ranging from approximately 20 to approximately 150 micrometres, are dissolved in tetrahydrofuran for one minute to concentration of a least approximately 500 parts/million and/or is characterised by average BET surface area greater than approximately 0.6 m2/g.

EFFECT: product can be extracted and purified using methods which are cheaper than those which can be used if the acid is obtained via a high-temperature oxidation method.

37 cl, 36 dwg, 5 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: method involves, for example: (a) evaporation of said oxidised discharge stream, containing terephthalic acid, metallic catalyst, impurities, water and solvent, in the first zone of an evaporator to obtain a vapour stream and a concentrated suspension of the discharge stream; and (b) evaporation of the said concentrated suspension of the discharge stream in the second zone of the evaporator to obtain a stream rich in solvent and a high-concentration suspension of the discharge stream, where the said second zone of the evaporator has an evaporator operating at temperature ranging from 20C to 70C, where from 75 to 99 wt % of the said solvent and water is removed by evaporation from the said oxidised discharge stream at step (a) and (b); (c) the said high-concentration suspension of the discharge stream is filtered in a zone for separating solid products and liquid to form a filtered product and a mother liquid; (d) washing the said filtered product using washing substances fed into the said zone for separating solid products and liquid to form a washed filtered product and washing filtrate; and dehydration of the said filtered product in the said zone for separating solid products and liquid to form a dehydrated filtered product; where the said zone for separating solid products and liquid has at least one pressure filtration device, where the said pressure filtration device works at pressure ranging from 1 atmosphere to 50 atmospheres; (e) mixing water and optionally extractive solvent with the said mother liquid and with all of the said washing filtrate or its portion in the mixing zone to form an aqueous mixture; (f) bringing the extractive solvent into contact with the said aqueous mixture in the extraction zone to form a stream of extract and a purified stream, where the said metallic catalyst is extracted from the said purified stream.

EFFECT: improved method of extracting metallic catalyst from an oxidised discharge stream obtained during production of terephthalic acid.

36 cl, 3 dwg, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of preparing a dry residue of aromatic dicarboxylic acid containing 8-14 carbon atoms, suitable for use as starting material for synthesis of polyester, where the said method involves the following sequence of stages, for example: (a) oxidation of aromatic material in the oxidation zone to obtain a suspension of carboxylic acid; (b) removal of impurities from the suspension of aromatic dicarboxylic acid in the liquid-phase mass-transfer zone where at least 5% liquid is removed, with formation of a residue or suspension of aromatic dicarboxylic acid, and a stream of mother solution, where the liquid-phase mass-transfer zone includes a device for separating solid substance and liquid; (c) removal of residual impurities from the suspension or residue of aromatic dicarboxylic acid obtained at stage (b) in the zone for countercurrent washing with a solvent to obtain a residue of aromatic dicarboxylic acid with the solvent and a stream of mother solution together with the solvent, where the number of steps for countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, and the said solvent contains acetic acid, (d) removal of part of the solvent from the residue of aromatic dicarboxylic acid together with the solvent obtained at stage (c) in the zone for countercurrent washing with water to obtain a residue of aromatic dicarboxylic acid wetted with water and a stream of liquid by-products together with the solvent/water, where the number of countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, where stages (b), (c) and (d) are combined into a single liquid-phase mass-transfer zone, and directing the residue of aromatic dicarboxylic acid wetted with water directly to the next stage (e), (e) drying the said residue of aromatic dicarboxylic acid wetted with water in the drying zone to obtain the said dry residue of aromatic dicarboxylic acid suitable for synthesis of polyester, where the said residue wetted with water retains the form of residue between stages (d) and (e).

EFFECT: design of an improved version of the method of preparing dry residue of aromatic dicarboxylic acid.

21 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a continuous stepped counterflow method of catalytic oxidation in a solvent of at least one benzene compound, containing two substituting groups, which are selected from alkyl, hydroxyalkyl, aldehyde, carboxyl groups and their mixtures, which can be oxidised to the corresponding acid derivative, involving the following steps: (a) introducing a mixture of material into the first oxidation step, containing at least part of the total amount of each of: (i) solvent, which is an organic acid, (ii) at least one catalytically active metal, selected from manganese, cobalt, nickel, zirconium, hafnium, cerium and their mixtures, and (iii) bromine in molar ratio, in terms of all catalytically active metals, in the interval from 1:20 to 5:1 and from 7 to 60 wt % of the total amount of at least one disubstituted benzene, introduced at steps (a) and (d); (b) partial oxidation of at least one disubstituted benzene at the first oxidation step in the presence of a gas, containing molecular oxygen initially in amount of 3 to 20 vol. %, at temperature ranging from 121C to 205C and relative quantities of disubstituted benzene, catalytic metal, solvent and bromine, introduced at step (a), so that from 25 to 99.95 wt % disubstituted benzene, added at the first oxidation step, is oxidised with formation of a gaseous mixture, containing unreacted molecular oxygen, evaporated solvent and a first mixture of products, containing acid derivative, partially oxidised disubstituted benzene, unreacted disubstituted benzene and solvent, and at pressure from 8.96105 to 14.8105 Pa, sufficient for keeping disubstituted benzene, partially oxidised disubstituted benzene, acid derivative and solvent in liquid state or in form of a suspension of solid substance in a liquid, so that concentration of residual molecular oxygen in the remaining gaseous mixture ranges from 0.3 to 2 vol. %; (c) extraction of the obtained first product mixture after the first oxidation step and supplying at least part of the extracted first product mixture to the second oxidation step; (d) supplying gas to the second oxidation step, containing molecular oxygen and residue form total amount of disubstituted benzene, catalytic metal, solvent and bromine; (e) oxidation at the second oxidation step of partially oxidised disubstituted benzene and unreacted disubstituted benzene, supplied to the second oxidation step, with a gas containing molecular oxygen in amount of 15 to 50 vol. %, at temperature ranging from 175C to 216C and relative quantities of disubstituted benzene, partially oxidised disubstituted benzene, catalytic metal, solvent and bromine, introduced at step (a), so that from 96 to 100 wt % disubstituted benzene and partially oxidised disubstituted benzene is oxidised with formation of a gaseous mixture, which contains unreacted molecular oxygen, evaporated solvent and a second product mixture, containing acid derivative and solvent, and at pressure from 11.7105 to 16.2105 Pa so as to keep the acid derivative, partially oxidised disubstituted benzene and unreacted disubstituted benzene mainly in liquid state or in form of a suspension of solid substance in a liquid, so that concentration of residual molecular oxygen in the remaining gaseous mixture ranges from 3 to 15 vol. %; (f) extraction after the second oxidation step of the second product mixture, containing acid derivative; and (g) tapping gas which contains residual molecular oxygen after the second oxidation step and returning it to the first oxidation step.

EFFECT: method allows for maximum use of oxygen without reducing quality of the desired carboxylic acid using a stepped counterflow oxidation system.

25 cl, 11 tbl, 29 ex, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method for oxidising of aromatic hydrocarbon such as para-xylol, meta-xylol, 2,6-dimethylnaphthalene or pseudocumene with forming of corresponding organic acid. The oxidation is implemented by the source of molecular oxygen in liquid phase at temperature range from 50C to 250C in the presence of catalyst being a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon. The invention refers also to the catalytic system for obtaining of organic acid by the liquid-phase oxidation of aromatic hydrocarbons representing: a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon.

EFFECT: activation of the aromatic hydrocarbons oxidation increasing the yield of target products and allowing to decrease the catalyst concentration and the temperature of the process.

45 cl, 4 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: method of obtaining product - purified carboxylic acid, includes: (a) oxidation of aromatic initial materials in primary oxidation zone with formation of raw carboxylic acid suspension; where raw carboxylic acid suspension contains terephthalic acid; where said oxidation is carried out at temperature within the range from 120°C to 200°C; (b) withdrawal of admixtures from raw suspension of carboxylic acid, removed at temperature from 140°C to 170°C from stage of oxidation of paraxylol in primary oxidation zone and containing terephthalic acid, catalyst, acetic acid and admixtures, realised in zone of solid products and liquid separation with formation of mother liquid flow and product in form of suspension; where part of said catalyst in said suspension of raw carboxylic acid is removed in said mother liquid flow; and where into said zone of solid products and liquid separation optionally additional solvent is added; (c) oxidation of said product in form of suspension in zone of further oxidation with formation of product of further oxidation; where said oxidation is carried out at temperature within the range from 190°C to 280°C; and where said oxidation takes place in said zone of further oxidation at temperature higher than in said primary oxidation zone; (d) crystallisation of said product of further oxidation in crystallisation zone with formation of crystallised product in form of suspension; (e) cooling of said crystallised product in form of suspension in cooling zone with formation of cooled suspension of purified carboxylic acid; and (i) filtration and optionally drying of said cooled suspension of purified carboxylic acid in filtration and drying zone in order to remove part of solvent from said cooled suspension of carboxylic acid with obtaining of said product - purified carboxylic acid.

EFFECT: purified carboxylic acid with nice colour and low level of admixtures, without using stages of purification like hydration.

8 cl, 1 tbl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention pertains to improved method of lowering content of 4-carboxybenzoldehyde and p-toluic acid in benzenedicarboxylic acid, which is terephtalic acid. Method involves: (1) supplying (i) p-xylene (ii) water acetic acid reaction medium, containing oxidation catalyst, containing source of cobalt, manganese and bromine source, dissolved in it, and (iii) acid containing gas in the first oxidation zone at high pressure, in which there is liquid phase, exothermal oxidation of p-xylene. In the first reactor, oxidation at high temperature and pressure is maintained at 150-165°C and 3.5-13 bars respectively; (2) removal from the upper part of the first reactor of vapour, containing water vapour, acetic acid reaction medium and oxygen depleted gas, and directing the vapour into the column for removing water; (3) removal from the lower part of the column for removing water of liquid, containing partially dehydrated acetic acid solution; (4) removal from the lower part of the first reactor of the oxidation product, containing (i) solid and dissolved terephtalic acid, 4-carboxybenzaldehyde and p-toluic acid, (ii) water acetic acid reaction medium, containing oxidation catalyst dissolved in it; (5) supplying (i) product of oxidation from stage (4), (ii) oxygen containing gas and (iii) solvent in vapour form, containing acetic acid, obtained from a portion of partially dehydrated acetic acid solvent from stage (3) into the second oxidation zone high pressure, in which there is liquid phase exothermal oxidation of 4-carboxybenzaldehyde and p-toluic acid, where temperature and pressure in the second reactor of oxidation at high pressure is maintained at 185-230°C and 4.5-18.3 bars respectively; (6) removal from the upper part of the second reactor of vapour, containing water vapour, acetic acid reaction medium, and oxygen depleted gas; (7) removal from the lower part of the second reactor of the product of second oxidation, containing (i) solid and dissolved terephtalic acid and (ii) water acetic acid reaction medium; and (8) separation of terephtalic acid from (ii) water acetic acid reaction medium from stage (7) with obtaining of terephtalic acid. The invention also relates to methods of obtaining terephtalic acid (versions). The obtained product is terephtalic acid, with an overall concentration of 4-carboxybenzaldehyde and p-toluic acid of 150 ppm or less.

EFFECT: improved method of lowering content of 4-carboxybenzoldehyde and p-toluic acid in benzenedicarboxylic acid and obtaining terephtalic acid.

13 cl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method, by which the carboxylic acid/diol mixture, that is suitable as the initial substance for the manufacture of polyester, obtained from the decolourised solution of carboxylic acid without actually isolating the solid dry carboxylic acid. More specifically, the invention relates to the method of manufacturing a mixture of carboxylic acid/diol, where the said method includes the addition of diol to the decolourised solution of carboxylic acid, which includes carboxylic acid and water, in the zone of the reactor etherification, where diol is located at a temperature sufficient for evaporating part of the water in order to become the basic suspending liquid with the formation of the specified carboxylic acid/diol mixture; where the said carboxylic acid and diol enter into a reaction in the zone of etherification with the formation of a flow of a complex hydroxyalkyl ether. The invention also relates to the following variants of the method: the method of manufacture of the carboxylic acid/diol mixture, where the said method includes the following stages: (a) mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of damp carboxylic acid; where the said carboxylic acid is selected from the group, which includes terephthalic acid, isophthatic acid, naphthalenedicarboxylic acid and their mixtures; (b) discolourisation of aforesaid solution of damp carboxylic acid in the zone for reaction obtaining the decolourised solution of carboxylic acid; (c) not necessarily, instantaneous evaporation of the said decolourised solution of carboxylic acid in the zone of instantaneous evaporation for the removal of part of the water from the decolourised solution of carboxylic acid; and (d) addition of diol to the decolourised solution of carboxylic acid in the zone of the reactor of the etherification, where the said diol is located at a temperature, sufficient for the evaporation of part of the water in order to become the basic suspending liquid with the formation of the carboxylic acid/diol mixture; where the aforesaid carboxylic acid and diol then enter the zone of etherification with the formation of the flow of complex hydroxyalkyl ether; and relates to the method of manufacture of carboxylic acid/diol, where the said method includes the following stages: (a) the mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of carboxylic acid; (b) discolourisation of the said solution of damp carboxylic acid in the reactor core with the formation of the decolourised solution of carboxylic acid; (c) crystallisation of the said decolourised solution of carboxylic acid in the zone of crystallisation with the formation of an aqueous suspension; and (d) removal of part of the contaminated water in the aforesaid aqueous solution and addition of diol into the zone of the removal of liquid with the obtaining of the said carboxylic acid/diol mixture, where diol is located at a temperature sufficient for evaporating part of the contaminated water from the said aqueous suspension in order to become the basic suspending liquid.

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention pertains to the perfection of the method of regulating quantities of dissolved iron in liquid streams during the process of obtaining aromatic carboxylic acids or in the process of cleaning technical aromatic carboxylic acids, characterised by that, to at least, part of the liquid stream for regulating the quantity of dissolved iron in it, at least one peroxide with formula R1-O-O-R2 is added. Here R1 and R2 can be the same or different. They represent hydrogen or a hydrocarbon group, in quantities sufficient for precipitation of the dissolved iron from the liquid. The invention also relates to the perfection of the method of obtaining an aromatic carboxylic acid, through the following stages: A) contacting the crude aromatic material which can be oxidised, with molecular oxygen in the presence of an oxidising catalyst, containing at least, one metal with atomic number from 21 to 82, and a solvent in the form of C2-C5 aliphatic carboxylic acid in a liquid phase reaction mixture in a reactor under conditions of oxidation with formation of a solid product. The product contains technical aromatic carboxylic acid, liquid, containing a solvent and water, and an off-gas, containing water vapour and vapour of the solvent; B) separation of the solid product, containing technical aromatic carboxylic acid from the liquid; C) distillation of at least part of the off gas in a distillation column, equipped with reflux, for separating vapour of the solvent from water vapour. A liquid then forms, containing the solvent, and in the upper distillation cut, containing water vapour; D) returning of at least, part of the liquid from stage B into the reactor; E) dissolution of at least, part of the separated solid product, containing technical aromatic carboxylic acid, in a solvent from the cleaning stage with obtaining of a liquid solution of the cleaning stage; F) contacting the solution from the cleaning stage with hydrogen in the presence of a hydrogenation catalyst and under hydrogenation conditions, sufficient for formation of a solution, containing cleaned aromatic carboxylic acid, and liquid, containing a cleaning solvent; G) separation of the cleaned aromatic carboxylic acid from the solution, containing the cleaning solvent, which is obtained from stage E, with obtaining of solid cleaned aromatic carboxylic acid and a stock solution from the cleaning stage; H) retuning of at least, part of the stock solution from the cleaning stage, to at least, one of the stages B and E; I) addition of at least, one peroxide with formula R1-O-O-R2, where R1 and R2 can be the same or different, and represent hydrogen or a hydrocarbon group, in a liquid from at least one of the other stages, or obtained as a result from at least one of these stages, to which the peroxide is added, in a quantity sufficient for precipitation of iron from the liquid.

EFFECT: controlled reduction of the formation of suspension of iron oxide during production of technical aromatic acid.

19 cl, 1 dwg, 6 ex, 4 tbl

FIELD: chemistry.

SUBSTANCE: herbs or fir tree bark which is dried, crushed or pre-treated with steam is extracted with an organic solvent with successive exposure to vacuum ranging from 70 to 380 mmHg and atmospheric pressure not less than two times. The extract is then poured off, dried with anhydrous magnesium sulphate. A mixture of biologically active substances is extracted by evaporation or a 2% solution of sodium hydroxide is added to the extract and left to stratify. After stratification, the aqueous-alkali layer is poured off, acidified with 10% hydrochloric acid to pH=2 and the mixture of triterpene acids is extracted using an organic solvent. The mixture of neutral isoprenoids is extracted from the remaining organic layer of the extract through evaporation.

EFFECT: increased output of the end product and cutting on extraction time.

6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method for liquid-phase carbonylation of reagent capable of carbonylation, selected from methanol and/or its reactive derivative to obtain a carbonylated product selected from acetc acid, acetic anhydride and their mixtures, involving bringing the reagent capable of carbonylation into contact with carbon monoxide in a liquid reaction composition in a reaction zone, where the said liquid reaction composition contains a carbonylation catalyst selected from iridium, rhodium and their mixtures, methyl iodide, salts of an alkali metal or alkali-earth metal, capable of generating iodide ions and corrosive metal impurities, where the liquid reaction composition is separated in a single equilibrium evaporation zone to obtain a vapour fraction containing a carbonylated product and a liquid fraction containing a carbonylation catalyst solution, where the said carbonylation catalyst solution contains a carbonylation catalyst, an alkali or alkali-earth metal and corrosive metal impurities, and where at least a portion of the carbonylation catalyst solution is returned to the reaction zone. The carbonylation catalyst solution returned to the reaction zone has low content of corrosive metal impurities and concentration of alkali or alkali-earth metal in the liquid reaction composition is controlled by bringing into contact at least a portion of the carbonylation catalyst solution with a cation-exchange resin whose active portions are partially saturated by a sufficient amount of alkali or alkali-earth metal.

EFFECT: obtaining carbonylation catalyst solution with low content of corrosive metal impurities with retention of concentration of alkali and/or alkali-earth metal in the catalyst solution at the same time.

20 cl, 13 ex, 2 tbl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of preparing a dry residue of aromatic dicarboxylic acid containing 8-14 carbon atoms, suitable for use as starting material for synthesis of polyester, where the said method involves the following sequence of stages, for example: (a) oxidation of aromatic material in the oxidation zone to obtain a suspension of carboxylic acid; (b) removal of impurities from the suspension of aromatic dicarboxylic acid in the liquid-phase mass-transfer zone where at least 5% liquid is removed, with formation of a residue or suspension of aromatic dicarboxylic acid, and a stream of mother solution, where the liquid-phase mass-transfer zone includes a device for separating solid substance and liquid; (c) removal of residual impurities from the suspension or residue of aromatic dicarboxylic acid obtained at stage (b) in the zone for countercurrent washing with a solvent to obtain a residue of aromatic dicarboxylic acid with the solvent and a stream of mother solution together with the solvent, where the number of steps for countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, and the said solvent contains acetic acid, (d) removal of part of the solvent from the residue of aromatic dicarboxylic acid together with the solvent obtained at stage (c) in the zone for countercurrent washing with water to obtain a residue of aromatic dicarboxylic acid wetted with water and a stream of liquid by-products together with the solvent/water, where the number of countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, where stages (b), (c) and (d) are combined into a single liquid-phase mass-transfer zone, and directing the residue of aromatic dicarboxylic acid wetted with water directly to the next stage (e), (e) drying the said residue of aromatic dicarboxylic acid wetted with water in the drying zone to obtain the said dry residue of aromatic dicarboxylic acid suitable for synthesis of polyester, where the said residue wetted with water retains the form of residue between stages (d) and (e).

EFFECT: design of an improved version of the method of preparing dry residue of aromatic dicarboxylic acid.

21 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: description is given of a method of selective removal of catalytic group VIII metals and carbonylation promoter metals from liquid compositions, containing carbonylation product, catalytic group VIII metals and carbonylation promoter metals, corrosion metals and optionally alkali or alkali-earth metals. The method involves bringing the said liquid composition into contact with a chelating resin to remove at least part of the iridium as a carbonylation catalyst and promoter metal contained in the liquid composition and wherein the chelating resin contains at least one thiourea functional group. The method is suitable for treating process streams obtained in the production of carboxylic acids and/or carboxylic acid anhydrides.

EFFECT: removal of catalytic metals and promoter metals mainly before corrosion metals from carbonylation process streams.

24 cl, 2 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: invention refers to advanced method of production of (meth)acrylic acid ester including (meth)acrylic acid purification by contacting raw (meth)acrylic acid containing manganese as an impurity manganese, and cation-exchange resin to remove manganese. To ensure contacting raw (meth)acrylic acid and cation-exchange resin, water is pre-added to (meth)acrylic acid. Besides, the method involves reaction of purified (meth)acrylic acid and alcohol with acid catalyst added.

EFFECT: method allows preventing effectively deactivation of the acid catalyst used in etherification reaction, equipment plugging and can ensure stable ester manufacturing.

3 cl, 5 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention relates to improved method of recovering (meth)acrolein or (meth)acrylic acid, including stage of cooling of gaseous reaction mixture containing (meth)acrolein or (meth)acrylic acid obtained by reaction of catalytic oxidation in vapour phase of one or both reagents selected from (A) propane, propylene or isobutylene and (B) (meth)acrolein, with molecular oxygen or gas, containing molecular oxygen, to temperature 140-250C; contacting of said gaseous reaction mixture with solvent, whose temperature is 20-50C, in recovery installation for recovering (meth)acrolein or (meth)acrylic acid in solvent, where said recovery installation contains contact zone, where gaseous reaction mixture contacts with solvent, having transversal section of round form and many devices of gaseous reaction mixture supply for supplying gaseous reaction mixture into contact zone, devices of gaseous reaction mixture supply are installed in contact zone at the same height directed towards contact zone centre, gaseous reaction mixture is supplied to contact zone from devices of gaseous reaction mixture supply and is subjected to collision straight in one point of contact zone, and recovery installation does not have device which prevents direct collision of gaseous mixture supplied from devices of gaseous reaction mixture supply. Invention also relates to recovery installation for recovering (meth)acrolein or (meth)acrylic acid.

EFFECT: ensuring efficient recovering (meth)acrolein or (meth)acrylic acid from gas containing (meth)acrolein or (meth)acrylic acid, preventing polymerisation.

7 cl, 5 dwg, 4 ex

FIELD: chemistry.

SUBSTANCE: present invention pertains to the method of obtaining a carboxylic/diol mixture, without release of dry solid carboxylic acid from a carboxylic acid/solvent suspension. More specifically, the present invention pertains to a method of obtaining a carboxylic acid/diol mixture, where the carboxylic acid is chosen from a group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid and their mixture. The method involves addition of diol for substituting water for precipitation of carboxylic acid, soaked in water, in the mixing zone of carboxylic acid/diol. Carboxylic acid precipitate, soaked in water, is obtained from precipitate of carboxylic acid with a solvent through washing with water.

EFFECT: obtaining a carboxylic acid/diol; release of dry solid carboxylic acid from a suspension of carboxylic acid/solvent.

31 cl, 1 ex, 1 dwg

FIELD: chemistry.

SUBSTANCE: method of obtaining product - purified carboxylic acid, includes: (a) oxidation of aromatic initial materials in primary oxidation zone with formation of raw carboxylic acid suspension; where raw carboxylic acid suspension contains terephthalic acid; where said oxidation is carried out at temperature within the range from 120°C to 200°C; (b) withdrawal of admixtures from raw suspension of carboxylic acid, removed at temperature from 140°C to 170°C from stage of oxidation of paraxylol in primary oxidation zone and containing terephthalic acid, catalyst, acetic acid and admixtures, realised in zone of solid products and liquid separation with formation of mother liquid flow and product in form of suspension; where part of said catalyst in said suspension of raw carboxylic acid is removed in said mother liquid flow; and where into said zone of solid products and liquid separation optionally additional solvent is added; (c) oxidation of said product in form of suspension in zone of further oxidation with formation of product of further oxidation; where said oxidation is carried out at temperature within the range from 190°C to 280°C; and where said oxidation takes place in said zone of further oxidation at temperature higher than in said primary oxidation zone; (d) crystallisation of said product of further oxidation in crystallisation zone with formation of crystallised product in form of suspension; (e) cooling of said crystallised product in form of suspension in cooling zone with formation of cooled suspension of purified carboxylic acid; and (i) filtration and optionally drying of said cooled suspension of purified carboxylic acid in filtration and drying zone in order to remove part of solvent from said cooled suspension of carboxylic acid with obtaining of said product - purified carboxylic acid.

EFFECT: purified carboxylic acid with nice colour and low level of admixtures, without using stages of purification like hydration.

8 cl, 1 tbl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method, by which the carboxylic acid/diol mixture, that is suitable as the initial substance for the manufacture of polyester, obtained from the decolourised solution of carboxylic acid without actually isolating the solid dry carboxylic acid. More specifically, the invention relates to the method of manufacturing a mixture of carboxylic acid/diol, where the said method includes the addition of diol to the decolourised solution of carboxylic acid, which includes carboxylic acid and water, in the zone of the reactor etherification, where diol is located at a temperature sufficient for evaporating part of the water in order to become the basic suspending liquid with the formation of the specified carboxylic acid/diol mixture; where the said carboxylic acid and diol enter into a reaction in the zone of etherification with the formation of a flow of a complex hydroxyalkyl ether. The invention also relates to the following variants of the method: the method of manufacture of the carboxylic acid/diol mixture, where the said method includes the following stages: (a) mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of damp carboxylic acid; where the said carboxylic acid is selected from the group, which includes terephthalic acid, isophthatic acid, naphthalenedicarboxylic acid and their mixtures; (b) discolourisation of aforesaid solution of damp carboxylic acid in the zone for reaction obtaining the decolourised solution of carboxylic acid; (c) not necessarily, instantaneous evaporation of the said decolourised solution of carboxylic acid in the zone of instantaneous evaporation for the removal of part of the water from the decolourised solution of carboxylic acid; and (d) addition of diol to the decolourised solution of carboxylic acid in the zone of the reactor of the etherification, where the said diol is located at a temperature, sufficient for the evaporation of part of the water in order to become the basic suspending liquid with the formation of the carboxylic acid/diol mixture; where the aforesaid carboxylic acid and diol then enter the zone of etherification with the formation of the flow of complex hydroxyalkyl ether; and relates to the method of manufacture of carboxylic acid/diol, where the said method includes the following stages: (a) the mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of carboxylic acid; (b) discolourisation of the said solution of damp carboxylic acid in the reactor core with the formation of the decolourised solution of carboxylic acid; (c) crystallisation of the said decolourised solution of carboxylic acid in the zone of crystallisation with the formation of an aqueous suspension; and (d) removal of part of the contaminated water in the aforesaid aqueous solution and addition of diol into the zone of the removal of liquid with the obtaining of the said carboxylic acid/diol mixture, where diol is located at a temperature sufficient for evaporating part of the contaminated water from the said aqueous suspension in order to become the basic suspending liquid.

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention pertains to the perfection of the method of regulating quantities of dissolved iron in liquid streams during the process of obtaining aromatic carboxylic acids or in the process of cleaning technical aromatic carboxylic acids, characterised by that, to at least, part of the liquid stream for regulating the quantity of dissolved iron in it, at least one peroxide with formula R1-O-O-R2 is added. Here R1 and R2 can be the same or different. They represent hydrogen or a hydrocarbon group, in quantities sufficient for precipitation of the dissolved iron from the liquid. The invention also relates to the perfection of the method of obtaining an aromatic carboxylic acid, through the following stages: A) contacting the crude aromatic material which can be oxidised, with molecular oxygen in the presence of an oxidising catalyst, containing at least, one metal with atomic number from 21 to 82, and a solvent in the form of C2-C5 aliphatic carboxylic acid in a liquid phase reaction mixture in a reactor under conditions of oxidation with formation of a solid product. The product contains technical aromatic carboxylic acid, liquid, containing a solvent and water, and an off-gas, containing water vapour and vapour of the solvent; B) separation of the solid product, containing technical aromatic carboxylic acid from the liquid; C) distillation of at least part of the off gas in a distillation column, equipped with reflux, for separating vapour of the solvent from water vapour. A liquid then forms, containing the solvent, and in the upper distillation cut, containing water vapour; D) returning of at least, part of the liquid from stage B into the reactor; E) dissolution of at least, part of the separated solid product, containing technical aromatic carboxylic acid, in a solvent from the cleaning stage with obtaining of a liquid solution of the cleaning stage; F) contacting the solution from the cleaning stage with hydrogen in the presence of a hydrogenation catalyst and under hydrogenation conditions, sufficient for formation of a solution, containing cleaned aromatic carboxylic acid, and liquid, containing a cleaning solvent; G) separation of the cleaned aromatic carboxylic acid from the solution, containing the cleaning solvent, which is obtained from stage E, with obtaining of solid cleaned aromatic carboxylic acid and a stock solution from the cleaning stage; H) retuning of at least, part of the stock solution from the cleaning stage, to at least, one of the stages B and E; I) addition of at least, one peroxide with formula R1-O-O-R2, where R1 and R2 can be the same or different, and represent hydrogen or a hydrocarbon group, in a liquid from at least one of the other stages, or obtained as a result from at least one of these stages, to which the peroxide is added, in a quantity sufficient for precipitation of iron from the liquid.

EFFECT: controlled reduction of the formation of suspension of iron oxide during production of technical aromatic acid.

19 cl, 1 dwg, 6 ex, 4 tbl

FIELD: chemistry.

SUBSTANCE: method involves, for example: (a) evaporation of said oxidised discharge stream, containing terephthalic acid, metallic catalyst, impurities, water and solvent, in the first zone of an evaporator to obtain a vapour stream and a concentrated suspension of the discharge stream; and (b) evaporation of the said concentrated suspension of the discharge stream in the second zone of the evaporator to obtain a stream rich in solvent and a high-concentration suspension of the discharge stream, where the said second zone of the evaporator has an evaporator operating at temperature ranging from 20C to 70C, where from 75 to 99 wt % of the said solvent and water is removed by evaporation from the said oxidised discharge stream at step (a) and (b); (c) the said high-concentration suspension of the discharge stream is filtered in a zone for separating solid products and liquid to form a filtered product and a mother liquid; (d) washing the said filtered product using washing substances fed into the said zone for separating solid products and liquid to form a washed filtered product and washing filtrate; and dehydration of the said filtered product in the said zone for separating solid products and liquid to form a dehydrated filtered product; where the said zone for separating solid products and liquid has at least one pressure filtration device, where the said pressure filtration device works at pressure ranging from 1 atmosphere to 50 atmospheres; (e) mixing water and optionally extractive solvent with the said mother liquid and with all of the said washing filtrate or its portion in the mixing zone to form an aqueous mixture; (f) bringing the extractive solvent into contact with the said aqueous mixture in the extraction zone to form a stream of extract and a purified stream, where the said metallic catalyst is extracted from the said purified stream.

EFFECT: improved method of extracting metallic catalyst from an oxidised discharge stream obtained during production of terephthalic acid.

36 cl, 3 dwg, 2 tbl, 2 ex

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