Method of removing impurities from mother liquids during synthesis of carboxylic acid using pressure filtration

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 20°C to 70°C, 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

 

The technical field to which the invention relates.

The present invention relates to the recovery of a metal catalyst from the oxidized waste stream produced in the synthesis of carboxylic acid, typically terephthalic acid, using filtration under pressure. More specifically, the method includes combining water with uterine fluid extraction of metal catalyst, and then the impact on water mixture, thus obtained, one-step extraction with an extraction solvent to remove organic impurities, to obtain the flow of the extract and purified stream containing a metal catalyst.

The level of technology

Terephthalic acid is produced in industry by oxidation of paraxylene in the presence of a catalyst, such as Co, Mn, Br and solvent. Terephthalic acid used in the production of polyester fibers, films and resins should additionally processed to remove impurities, resulting from the oxidation of paraxylene.

Terephthalic acid (TPA) is an intermediate product in the production of polyesters for applications involving plastics and fibers. Industrial methods of production TRA are often based on the oxidation of p-xylene catalyzed by heavy metals, as a rule, with bromidum promoter, solvent-based acetic acid. Due to the limited solubility of TPA in acetic acid under practical conditions of oxidation, the oxidation reactor is typically formed suspension of crystals of TPA. As a rule, the suspension of TPA in the oxidant is removed from the reactor, and the solid TPA products are separated from the mother liquid oxidizer using conventional separation technologies of solid food and liquids. Uterine fluid oxidant, which contains most of the catalyst and promoter used in the way that is recycled to the oxidation reactor. In addition to the catalyst and promoter, the flow of the uterine fluid oxidant also contains dissolved TPA and many by-products and impurities. These by-products and impurities arise partly due to the microscopic impurities present in the input stream p-xylene. Other impurities arise due to incomplete oxidation of p-xylene, leading to the formation of partially oxidized products. Other types of by-products result from the competitive side reactions arising from oxidation of p-xylene to terephthalic acid. Patents describing the production of terephthalic acid, such as U.S. patent No. 4158738 and 3996271, thus, are included as references in their entirety, to the extent, for instance, is as they do not contradict the wording used here.

Solid foods TPA subjected to separation of solids and liquids, when fresh solvent is used to replace the main part of the liquid component of the uterine fluid oxidant. After drying, the solid TPA products contaminated with impurities that are present in the uterine fluid oxidant, because these impurities can be included in solid foods TPA. Impurities are also present due to impurities in the crystal structure of TPA and due to incomplete removal of uterine fluid oxidant by washing with fresh solvent.

Many of the impurities in the mother liquor stream of oxidant, which get recycled, are relatively inert during subsequent oxidation. Such impurities include, for example, isophthalic acid, phthalic acid and trimellitic acid. Also contains impurities that can undergo oxidation in the future, such as 4-carboxybenzene, p-toluene acid and p-tolualdehyde. Inert under the oxidation impurities tend to accumulate in the uterine fluid oxidant when recycling. The concentration of these inert impurities will increase in uterine fluid oxidizer until then, until equilibrium is reached, and the rate of removal of impurities by each product TPA will be counterbalanced by the speed coord the speed and add in the way of oxidation. The usual level of impurities in industrial crude TPA makes it unsuitable for direct use in most polymer applications.

Usually crude TPA purified either by converting dimethyl ether complex, or by dissolving in water, followed by hydrogenation over a standard hydrogenation catalysts. Later secondary oxidation processing was used to obtain TPA polymer quality. It is desirable to minimize the concentration of impurities in the mother liquor, thereby facilitating subsequent purification of TPA. In some cases, it is impossible to obtain the purified TPA polymer quality, if only you do not use any tools to remove impurities from a stream of mother liquor oxidant.

One of the technologies for removing impurities from a stream of recycle commonly used in the chemical processing industry is pumping or "cleansing" of some part of the stream being recycled. Typically, the oxidized stream reset just released or, at an economical operation of the process, is exposed to various types of processing to remove undesirable impurities, at the same time, extraction of valuable components. One example is the U.S. patent No. 4939297 included here as a reference in it is anote, to the extent it does not contradict the wording used here. The amount of cleaning required for the control of impurities depends on the way; however, the amount of cleaning that is equal to 10-40% of the total flow of uterine fluid oxidant, usually is enough to get TRA adequate, the quality of the supplied materials for the industrial production of polymers. In the production of TRA percentage of cleansing stream uterine fluid oxidant required to maintain acceptable concentrations of impurities, in combination with cost-effective amount of a metal catalyst and components of the solvent in the oxidized stream reset makes a simple release of the oxidized stream reset economically unattractive. Thus, there is a need for a method that removes essentially all precious metal catalysts and acetic acid contained in the oxidized stream reset at the same time removing most of the impurities present in the oxidized stream reset. The metal catalyst can be removed in the active form suitable for reuse, using direct recycling at the stage of oxidation of p-xylene.

The present invention represents a significant improvement compared with the conventional method of cleaning. Some ol the property are:

1) improved performance and reliability by reducing the likelihood of clogging;

2) reduction of total energy intake;

3) reducing the amount of water for the stage of extraction solvent.

The present invention increases the efficiency of removal of impurities and method of operation of the method compared to existing methods. In addition, it should be noted that the present invention is not only applicable to the method of obtaining the crude TPA, but any method that produces oxidized stream reset that require removing the metal catalyst.

The invention

The present invention relates to the removal of impurities and removing the metal catalyst from the oxidized stream discharge obtained in the synthesis of carboxylic acid, typically terephthalic acid. More specifically, the method includes combining water with uterine fluid to extract the metal catalyst, and then the impact on water mixture, thus obtained, one-step extraction using an extraction solvent, to obtain the flow of the extract and purified stream containing a metal catalyst.

The aim of the present invention is to provide a method for extracting a flow of the metal catalyst from the oxidized stream the Bros through the use of high pressure filter.

Another objective of the present invention is to provide a method for removal of impurities and recovery of flow of the metal catalyst from the oxidized stream discharge obtained in the synthesis of carboxylic acids, which include the use of high pressure filter.

In the first embodiment, the present invention provides for a method. The method includes:

(a) filtering the concentrated slurry discharge into the zone of separation of solids and liquids with the formation of the filtered material and the mother liquor;

(b) washing the specified filtered material using the supplied wash materials in this zone separating solids and liquids, with the formation of the washed filtered material and the wash filtrate; and optional dehydration specified washed filtered material in this zone separating solids and liquids, with the formation of dehydrated filtered material; where the specified zone separating solids and liquids includes at least one device filtering under pressure.

In another embodiment, the present invention provides for a method. The method includes:

(a) the impact on the oxidized stream discharge containing carbon is th acid, a metal catalyst, impurities, water and solvent evaporation in the first zone of the evaporator, to obtain the flow of steam and a concentrated suspension flow discharge; and

(b) effect on the specified concentrated slurry discharge evaporation in the second zone of the evaporator, receiving stream enriched solvent, and a highly concentrated suspension flow discharge, where this second zone of the evaporator contains the area of the evaporator, operating at a temperature of approximately 20°to approximately 70°C;

(c) filtering the specified highly concentrated suspension flow discharge in the zone of separation of solids and liquids with the formation of the filtered material and the mother liquor;

(d) washing the specified filtered material using the supplied wash materials in this zone separating solids and liquids, with the formation of the washed filtered material and the wash filtrate; and optional dehydration specified washed filtered material in this zone separating solids and liquids, with the formation of dehydrated filtered material; where the specified zone separating solids and liquids includes at least one device filtering under pressure.

In another embodiment, the infusion is its invention provides a method for extracting metal catalyst from the oxidized stream reset. The method includes:

(a) effects on specified oxidized stream discharge containing carboxylic acid, the specified metal catalyst, impurities, water and solvent evaporation in the first zone of the evaporator, to obtain the flow of steam and a concentrated suspension flow discharge;

(b) effect on the specified concentrated suspension flow discharge in the second zone of the evaporator, with the formation of a stream enriched solvent, and a highly concentrated suspension flow discharge;

(c) filtering the concentrated suspension flow discharge in the zone of separation of solids and liquids with the formation of the filtered material and the mother liquor;

(d) washing the specified filtered material supplied to the washing materials within the specified area separating solids and liquids, with the formation of the washed filtered material and the wash filtrate; and optional dehydration specified washed filtered material in this zone separating solids and liquids, with the formation of dehydrated filtered material; where the specified zone separating solids and liquids includes at least one device filtering under pressure;

(e) mixing in the zone of mixing water and, optionally, extraction the second solvent with the specified uterine fluid and with all these wash filtrate or part of it, with the formation of the aqueous mixture;

(f) bringing into contact of the extraction solvent with the specified water mixture in the zone of extraction, with the formation of flow of the extract and purified stream; and

(g) separation of the specified extract stream in the separation zone, with the formation of the flow of organic impurities with high boiling point and the extracted flow of the extraction solvent.

These objectives and other objectives will become more understandable to experts in this field after reading the present description.

Brief description of drawings

Figure 1 illustrates various embodiments of the present invention, which provides a way to extract the metal catalyst from the oxidized stream reset 101, and a way of separating organic impurities from the concentrated slurry stream reset 145.

Figure 2 illustrates a variant implementation of the method according to the present invention, implemented in the area of separation of solids and liquids 151, which contains the area of the filter 153, the zone of leaching 155 and, optionally, the dehydration zone 157.

Figure 3 illustrates a variant of implementation of the present invention, where a rotary drum filter high pressure is used in the zone of separation of solids and liquids.

Description of the invention

In one embodiment, done by the means of the present invention provides a method of extraction of the metal catalyst from the oxidized stream reset 101, as shown in figure 1 and figure 2. The method includes the following stages.

Stage (a) includes the impact on the oxidized stream reset 101 evaporation in the first zone of the evaporator 121, with the receipt of the steam flow 104 and the concentrated slurry stream reset 105.

The oxidized stream reset 101 is extracted from the method of oxidative synthesis of carboxylic acids. The oxidized stream reset 101 serves as a flow of supplied materials for this method. The oxidized stream reset 101 contains a carboxylic acid, water, a solvent, a metal catalyst and impurities. Impurities include organic bromides, correlated metals, by-products of the oxidation of p-xylene and impurities resulting from the presence of impurities in the p-xylene. Organic bromides can be used as promoters in oxidation reactions. Examples of correlated metals are compounds of iron and chromium, which inhibit, reduce or completely destroy the activity of the metal catalyst. In addition to the catalyst and promoter, the flow of the uterine fluid oxidant also contains by-products and impurities. These by-products and impurities arise, in part, due to the microscopic impurities present in the feed flow of the material of the p-xylene. Other impurities arise from incomplete is R p-xylene, leading to the partially oxidized products. Other types of by-products result from the competitive side reactions in the oxidation of p-xylene to terephthalic acid.

Carboxylic acid include aromatic carboxylic acids, obtained by controlled oxidation of the organic substrate. Such aromatic carboxylic acids include compounds with at least one carboxylic acid group attached to the carbon atom that is part of an aromatic ring, preferably having at least 6 carbon atoms, more preferably having only carbon atoms. Relevant examples of such aromatic rings include, but are not limited to, benzene, biphenylene, terpinolene, naphthalene and other fused aromatic ring carbon-based. Examples of the corresponding carboxylic acids include, but are not limited to, terephthalic acid, benzoic acid, p-toluene acid, isophthalic acid, trimellitic acid, naphthaleneboronic acid, 2,5-diphenylethanol acid and mixtures thereof.

Appropriate solvents include, but are not limited to, aliphatic monocarboxylic acid, preferably containing 2 to 6 carbon atoms, or benzo is you acid, and their mixtures, and mixtures of these compounds with water. Preferably the solvent is an acetic acid mixed with water at a ratio of about 5:1 to about 25:1, preferably in the range between about 8:1 and about 20:1. In the description of acetic acid will be referred to as the solvent. However, it should be understood that other suitable solvents, such as those described previously, may also be used.

In the first stage of this method, the oxidized stream reset 101 is concentrated by conventional means in the first zone of the evaporator 121 containing the evaporator, with the receipt of the steam flow 104 and the concentrated slurry stream reset 105. The evaporator operates at atmospheric conditions or at a pressure slightly above atmospheric, typically from about 1 atmosphere to about 10 atmospheres. The steam flow 104 contains most of the water and solvent, and the concentrated slurry stream reset 105 contains the remaining water and solvent, is not remote from the oxidized stream reset 101. Evaporation removes from about 50 wt.% to about 80 wt.% solvent and water, as a rule, acetic acid and water, which are present in the oxidized stream reset 101.

Stage (b) puts the specified concentrated slurry stream reset 105 evaporation in the second zone Ipari the El 150, obtaining a stream enriched solvent 144, and the concentrated slurry stream reset 145.

The second zone of the evaporator 150 contains at least one evaporator operating under vacuum conditions. The evaporation may be carried out at temperatures from about 20°to about 70°C, other range is from about 30°to about 50°C. the Combination of evaporators 121 and 150 works in order to concentrate the oxidized stream discharge, as represented by flow 101, to a state where it is removed from about 75 wt.% to about 99 wt.% solvent and water, as a rule, acetic acid and water. Another range for the combination of evaporators 121 and 150 is designed for the concentration of oxidized stream discharge, as represented by flow 101, to a state where it is removed from about 85 wt.% to about 99 wt.% solvent and water, as a rule, acetic acid and water. Further, the ranges given in the present description and the claims that follow on, should be understood as describing specifically the entire range, not just the end point (point). For example, the description of the range from 0 to 10 has to be taken for a specific description of the 2, 2,5, 3,17 and all other included numbers, and not only 0 and 10.

In one of the embodiments of the present invention, the state high is concentrated suspension flow reset 145 may be a mixture of solids and liquids with the amount of solvent, sufficient only to provide pumping.

Stage (C) comprises filtering the concentrated slurry stream reset 145 in the zone of separation of solids and liquids 151, with the formation of the filtered material 154 and the mother liquor 147; and

stage (d) washes specified filtered material on the filter 154 using the supplied wash materials 149 in this zone separating solids and liquids 151, with the formation of the washed filtered material 146 and the wash filtrate 148; and optional dehydrates specified washed filtered material 146 in this zone separating solids and liquids 151, with the formation of dehydrated filtered material 159; where the specified zone separating solids and liquids 151 includes at least one device filtering under pressure.

A highly concentrated slurry stream reset 145 is introduced into the separation zone of solid foods and liquids 151 containing the area of the filter 153 and the zone of leaching 155 and, optionally, in the area of drying 157, as shown in figure 2. The area of the filter 153 contains the cell filter or a number of filter cells, which are physically located so as to allow the filtered material 154 for the development of the distribution area of the cell filter to weary and to prevent channeling of the supplied wash materials 149 through the filtered material 154.

Convenient to the filtered material 154, at least 0.25 inches at a depth of approximately 8 inches in depth, preferably at least 0.5 inches in depth, preferably at least 1 inch in depth, and even more preferably from about 2 to about 4 inches in depth, divided into square cells of the filter. The washed filtered material 146 can be removed or further processed to retsiklirovaniya and/or sent in the equipment for processing waste.

Upon receipt of the appropriate or preferred height of the filtered material 154, from about 0.5 inch to 4 inches, the filtered material 154 leaves the area of the filter 153, which contains a filter or series of filters, and gets into the zone of leaching 155, where the filtered material 154 comes into contact with the supplied wash materials 149. There is pressure on the filtered material 154, sufficient to create a reservoir or layer of the supplied wash materials 149 over the washed filtered material 154, preferably with appropriate depth, with a minimum depth of 0.25 inches. The pressure gradient of at least 0.5 psi, preferably from about 5 psi to about 65 psi, can be applied on the filtered material 154 and reservoirs is e supplied wash materials 149, to displace any dissolved solids in the filtered material 154 using the supplied wash materials 149.

The depth of the filtered material 154, at least 0.5 inch is suitable for receiving the filtered material 154 with compact sufficient to create filler for washing, that is, the filtered material 154, through which the wash filtrate 148 containing the dissolved substance from the filtered material 154, can effectively be removed by pressure washing. If the depth of the filtered material 154 is less about than 0.25 inch, may be channeling supplied wash materials 149 in the filtered material 154, leading to inhomogeneous washing the filtered material 154.

Because of the loss of efficiency when pressure washing the filtered material 154 minimum depth of filtered material 154, at least 0.25 inches from the purified terephthalic acid is preferred.

The minimum height of the liquid above the surface of the filtered material 154 must ensure that implemented such pressure washing. The height must be sufficient to ensure that the surface of the filtered material 154 was completely covered served the mi wash materials 149. If the surface of the filtered material 154 is not covered with the supplied wash materials 149, may wrap the supplied wash materials 149 without adequate displacement of the solute in the filtered material 154. Because of the irregularities of the surfaces of the filtered material 154, the minimum height of the liquid is from about 0.25 inch above the surface of the filtered material 154 is preferred.

Found that the displacement of the solute from the filtered material 154 using the supplied wash materials 149 at high pressure enables efficient selection of the metal catalysts from the filtered material 154. Another benefit of high pressure is to reduce the amount of wash materials 149, necessary for the extraction of cobalt, as shown in the examples.

The use of additional stages in the zone of separation of solids and liquids 151 can reduce the amount of wash materials 149 required to reduce the total amount of the metal catalyst held in the filtered material 154. For this reason, it is convenient to use the appropriate number of degrees of positive pressure washing to minimize the total is about the amount of wash materials 149, used in pressure washing, to reduce the need for further devices for waste processing.

It is understandable that many steps of the procedure, pressure washing can replace single-stage procedure, pressure washing, where the quantity of wash materials 149 is sufficient to obtain at least 80% recovery of the metal catalyst of highly concentrated suspensions 145, in mother liquor 147 and the wash filtrate 148. In addition, a procedure that uses multiple-speed counter-current rinsing, may be suitable for use, if reducing the amount of wash materials 149 must be predominant, as defined.

In the method according to the present invention, a highly concentrated slurry stream reset 145 is introduced into one or more rows of cells on filters, which are physically located in such a way as to enable the filtered material 154 for the development of the desired thickness.

When receiving the minimum height of the filtered material 154, from about 0.25 to about 4 inches, the filtered material 154 leaves the filter or series of filters and enters the zone of leaching 155, where the filtered material 154 washed supplied wash material 149. Then p is given by the washing materials 149 can be applied pressure, to displace the dissolved substance (i.e. liquid and any dissolved compounds, such as metal catalyst in the filtered material) from the filtered material 154. When the displacement of the solute using the supplied wash materials filtered material 154 can be produced from the zone filter 155 using any suitable for the use of funds, and the cycle repeats. In one of the embodiments of the present invention the ratio of the supplied wash materials 149 to material released from the filtered material 154 is in the range of from about 1:20 to about 20:1, to reduce the level of metal catalyst in the filtered material is more than 95%.

Equipment for carrying out the required wash cycle may include a number of cells of filters supported in an appropriate position to allow for the development layer of the supplied wash materials 149 on cells of filters. In one of the embodiments of the present invention corresponding equipment may include a rotary drum filter high pressure cells of filters connected with the means for releasing the washed filtered material 146 cell filters. The filtered material is 154 can be washed as many times how much is required for the development of the minimum concentration of metal catalyst in the washed filtered material 146, before the release of the washed filtered material 146 of the rotary drum filter.

The corresponding high pressure filter, which can adapt to the requirements of the method according to the present invention is a rotary drum filter high pressure BHS-FEST™, BHS-WERK, Sonthofen, D-8972, Sonthofen, West Germany, although other filters high pressure, which can carry out the necessary operations can be used. Examples of other devices that can be used in the zone of separation of solids and liquids include 151, but not limited to; tape high pressure filters, filter presses, centrifuges, leaf filters, high pressure filters with cross flow. The high pressure filter can operate at a temperature and pressure sufficient to obtain at least 80% recovery of the metal catalyst from the solute mother liquor 147.

Preferably the high pressure filter can operate at a temperature of from about 25°C. to about 160°C. and at a pressure of from 1 atmosphere to 50 atmospheres.

When filter BHS-FEST™ rotary drum contains a number of filter cells, located on periphery the rotating drum. When the drum rotates, cell filters take highly concentrated slurry stream reset 145, and creates a layer of filtered material 154 required depth. Mother liquor 147 is obtained by filtering the concentrated slurry stream 145. During the rotation of the drum filtered material 154 enters the zone of leaching 155, where a reservoir supplied wash materials 149 over the washed filtered material 154, to the required depth. The pressure applied to the reservoir supplied washing materials, forces the water through the filtered material 154, displacing the dissolved substance (solute metal catalyst), held in highly concentrated slurry stream reset 145, obtaining washed filtered material 146. Upon further rotation of the drum of the washing cycle may be repeated at least three times, if necessary, a counter-current manner, after which the system pressure is released, with a corresponding reduction of the temperature to ambient conditions. Optionally, the washed filtered material 146 may be dehydrated in the dehydration zone 157, with the help of steam through the passage 152, getting dehydrated filtered material 159 and wet steam 160. Then the obtained dehydrated is filtrowanie material 159 may be released from the drum by any conventional means.

Figure 3 illustrates a variant of implementation of the present invention, where a rotary drum filter high pressure used in the method as a filter device. In one of the embodiments of the present invention a rotary drum filter high pressure zone contains filter 153, the zone of leaching 155, optional, area of dehydration 157, zone release 164 and Laundry area 162. Area washing, shown in figure 3, is a variant of implementation of the present invention, where a rotary drum filter high pressure zone contains washing 162, where the filters are washed after release dehydrated filtered material 159.

Wash filtrate 148 receive by pressure washing the filtered material using the supplied wash materials 149. The filtered material 154 in the zone of separation of solids and liquids 151 is subjected to extraction of the metal catalyst through the introduction of the supplied wash materials 149, with the formation of the wash filtrate 148, where in one of the embodiments of the present invention, at least 80% of the metal catalyst is recovered from the wash filtrate and the mother liquor 147. In one of the embodiments of the present invention, Myung is our least 90% of the metal catalyst is recovered from the wash filtrate 148 and the mother liquor 147. Mother liquor 147 and the wash filtrate 148 can optionally be combined before exiting the zone of separation of solids and liquids 151.

Supplied wash materials 149 contain water and, optionally, additional oxidizing solvent.

Perhaps the most unexpected is that when using water as supplied wash materials 149, at temperatures in the range of about from 20°C to about 70°C, preferably from about 30°C to about 50°C, a sufficient amount of corroding metal is held in a dehydrated filtered material 159, this eliminates the need to remove corrosive metal by other means. Dehydrated filtered material 159, which is a solid products, peeled from the metal catalyst can be produced from the system.

Stage (e) includes the mixing in the mixing zone 122 water 106 and, optionally, the extraction solvent 108 with uterine fluid 147 and wash filtrate 148, with the formation water mixture 107. In one of the embodiments of the present invention, the mixing zone 122 includes a conventional mixer. If necessary, water 106 may dasavletis is in the mixing zone 122 in number, sufficient to dissolve the metal catalyst in the stream water mixture 107.

Typically, about 0.1-1.0 part of water per part of combined mother liquor 147 and wash filtrate 148 is sufficient to dissolve the catalyst, preferably from about 0.5 to 1 part of the mass. Desirable is to maintain water mixture 107 circulating through the external circuit. A small amount of extraction solvent 108, typically from about 1 to about 10 wt.%, preferably less than 5 wt.%, can be added in the mixing zone 122, to facilitate manipulation of the suspension by reducing the adhesion of solid products to the walls of the container. This is represented by a dashed arrow from the stream 108 in figure 1. Is desirable, but not required, impact on water mixture 107, before extraction, heat treatment at about 60°C to about 95°C, other range is from about 80°C to about 90°C, for about 0.5 to about 4 hours, preferably from about 1 to about 2 hours. Through this processing of organic bromides interact with obtaining inorganic bromides, which are preferably held in a purified stream 110. Thus minimises the number bromodomain compounds that are removed from the istemi together with undesirable impurities. Heat treatment saves bromides and facilitates the release of organic impurities.

Stage (f) comprises bringing into contact of the extraction solvent 108 with an aqueous mixture of 107 in the area of extraction 123, with the formation of the extract stream 109 and purified stream 110.

The aqueous mixture 107 is introduced into the zone of extraction 123, where water mixture 107 and extraction solvent 108 come into contact in the zone of extraction 123. The aqueous mixture 107 and extraction solvent 108 is mixed with a stream of the extract 109 containing solvent, water, organic impurities and extraction solvent, which forms a lighter phase and a purified stream 110 containing a metal catalyst, corroding metals and water. The extract stream 109 is extracted as the head stream and the purified stream 110 is extracted from the bottom of the extractor in the area of extraction 123. In the present invention one of the embodiments of the extraction zone 123 is a single-stage extractor.

Extraction solvent 108 used in the extractor should be essentially immiscible with water, to minimize the amount of organic solvent dissolved in the aqueous fraction. In addition, the extraction solvent 108 preferably is an azeotrope of the first agent, which serves to facilitate the extraction of the solvent from the organic extract. Solvents, which, as shown, are particularly suitable for use, represent a C1-C6 allylacetate, in particular n-propyl, isopropylacetate, isobutyl acetate, sec-butyl acetate, ethyl acetate and n-butyl acetate, although other essentially immiscible with water, organic solvents having an appropriate density and relatively low boiling point, such as p-xylene, may also be used. n-Propyl and isopropylacetate are especially preferred due to their relatively low Miscibility with water and excellent azeotropic behavior.

The extraction may be carried out by using the ratio of solvents is from about 1-4 parts mass extraction solvent to the aqueous mixture. Although the extraction can be operated at temperature and ambient pressure, can be used to heat the solvent and extractor approximately 30°C to about 70°C, other range represents about 40°C to about 60°C. While the flow of the extract 109 contains a small amount of metal catalyst and corroding metals, essentially all of the metal catalyst and most of the remaining corroding metals contained in more than the heavy phase, in a purified stream 110.

Stage (g) includes the separation of the extract stream 109 in the separation zone 124, receiving a stream of organic impurities with high boiling point 115 and the flow of the extracted extraction solvent 117.

The extract stream 109 contains an organic solvent and organic impurities. The extract stream 109 may further comprise acetic acid and water, often in microscopic quantities. The extract stream 109 may distilleries in the separation zone 124 containing the usual equipment for distillation. Conventional equipment for distillation includes, for example, the distillation column.

A large part of the organic impurities is extracted using an organic solvent in the zone of extraction 123. This is because organic impurities demonstrate a high level of solubility for an organic solvent and, to a lesser extent, for acetic acid. By distillation of the lighter phase from the extractor organic solvent is evaporated, allowing the organic impurities to concentrate in the stream from the bottom of the column.

The extracted stream extraction solvent 117 may retsiklirovaniya in the extractor in the area of extraction 123. The flow of organic impurities with high boiling point 115 BPM which is in the form of sediment from the base of distillation columns for release.

Examples:

The present invention can further be illustrated using the following examples of his other embodiments, although it will be understood that these examples are included here for illustrative purposes only and are not intended to limit the present invention unless specifically indicated.

Example 1

The purpose of these examples is to illustrate the extraction of the cobalt catalyst from the highly concentrated slurry stream reset 145 with a minimum of supplied wash materials 149. The following example illustrates the power vacuum filtration, using a filter funnel laboratory type. Data generated below, are applicable to the boot or continuous vacuum filters.

Laboratory filter device consists of a filter funnel with a filter surface area of 100 cm2placed in the upper part 4-liter vacuum flask. The vacuum system provides a vacuum of 0.6 bar at a flow rate of approximately 150 m3/h per m2square filtering. Vacuum system include, and 600 grams of the slurry containing 20% solids of a highly concentrated suspension flow reset 145, at 40°C, loaded onto the filter. Record the time of the first appearance of the filtered material 154 (the time of occurrence of dry tops). The filtered material 154 provide an opportunity for dehydration for an additional 10 seconds. Given the amount of wash materials 149, at 40°C, containing water, then pour on top of the filtered material 154. Register before the arrival of the filtered material 154 after adding the supplied wash materials 149. The filtered material 154 receives the opportunity to dehydration for an additional 20 seconds. Record the height of the filtered material 154, the mass of the filtered material 154, the percentage of humidity of the filtered material 154, the weight of the mother liquor 147 and a lot of wash filtrate 148. The dehydrated samples of the filtered material is subjected to the analysis of interest rate bulk cobalt content.

The procedure above is repeated 6 times with wash respect from 0 to 5. Wash ratio is defined as the grams of water supplied 149 per gram of dry solids in the filtered material 154. % The mass of cobalt in the washed filtered material at the respective washing the relations shown in table 1, below:

Table 1
Wash relationwt.% cobalt is
02,93%
12,37%
20,78%
30,36%
40,05%
50,03%

Severe cracking of the filtered material 154 see directly after the appearance of dry tops in each experiment, resulting in no visible dehydration filtered material 154 after the appearance of dry tops. The obtained filtered materials have an average humidity of 56%.

Example 2

The following example illustrates the possibility of filtration under pressure using a 1-liter laboratory high pressure filter BHS-FEST™.

Laboratory device consists of a 1-liter laboratory high pressure filter BHS-FEST™ with square filter 20 cm2. 1 litre chemical glass placed under the high pressure filter on the scales, for receiving the mother liquor and wash filtrate. Nitrogen is supplied under a pressure of 2 bar, flows into the filter after adding a highly concentrated slurry stream reset 145.

89 grams vysokokonkurenten the tub suspension stream reset 145, 20% solids load in the filter. Uterine fluid collected in 1-liter beaker. 7 seconds is an intensive penetration of nitrogen. The flow of nitrogen is stopped, the filter open, and 39 grams of the supplied wash materials 149, at 40°C add. Filter seal, and launch a stream of nitrogen. After 30 seconds, there is intense penetration of gas, and another 30 seconds to a stream of nitrogen to give the opportunity for dewatering the washed filtered material 146. Dehydrated filtered material 159 is removed from the filter, and received % moisture content of the filtered material is 40%. The results of the filtration under pressure is shown below.

Table 2
Wash relationThe filtered material is cobalt, wt.%
20,13

In contrast, vacuum filtering example 1 requires a flush relationship of 3.75 to obtain the level of cobalt filtered material of 0.13 wt.%, while filtering under pressure from example 2 only requires washing of approximately 2. Vacuum filtration requires 87% higher than the wash water than Phil is travanj under pressure.

1. The method of extraction of the metal catalyst from the oxidized waste stream of mother liquor obtained in the production of terephthalic acid, including:
(a) evaporation of the specified oxidized stream discharge, containing terephthalic acid, a metal catalyst, impurities, water and a solvent, in the first zone of the evaporator, to obtain the flow of steam and a concentrated suspension flow discharge; and
(b) evaporating the specified concentrated suspension flow discharge in the second zone of the evaporator, receiving stream enriched solvent, and a highly concentrated suspension flow discharge, where this second zone of the evaporator includes an evaporator operating at a temperature of from 20 to 70°C, 75 to 99 wt.% the specified solvent and water summarily removed by evaporation from the specified oxidized stream reset at stage (a) and (b);
(c) filtering the specified highly concentrated suspension flow discharge in the zone of separation of solids and liquids with the formation of the filtered product and the mother liquor;
(d) washing the specified filtered product using the supplied washing substances in a specified zone of separation of solids and liquids with the formation of the washed filtered product and the wash filtrate; and dehydration specified the CSOs filtered product in a specified zone of separation of solids and liquids with the formation of dehydrated filtered product; where the specified zone separating solids and liquids includes at least one device filtering under pressure, where the specified device, filtration under pressure operates at a pressure of from 1 to 50 atmospheres;
(e) mixing in the zone of mixing water and, optionally, the extraction solvent with the specified uterine fluid and with all these wash filtrate or any part thereof, with the formation of the aqueous mixture;
(f) bringing into contact of the extraction solvent with the specified water mixture in the zone of extraction with the formation of flow of the extract and purified stream, where the specified metal catalyst is extracted from the indicated purified stream.

2. The method according to claim 1, in which from 50 to 80 wt.% the specified solvent and water is removed by evaporation from the specified oxidized stream reset at stage (a).

3. The method according to claim 1, wherein from 85 to 99 wt.% the specified solvent and water summarily removed by evaporation from the specified oxidized stream reset at stage (a) and phase (b).

4. The method according to claim 1, wherein from 90 to 99 wt.% the specified solvent and water summarily removed by evaporation from the specified oxidized stream reset at stage (a) and phase (b).

5. The method according to claim 1, wherein the specified second zone of the evaporator includes an evaporator that operates in usloviahlinim.

6. The method according to claim 1, in which the specified device, filtration under pressure operates at a temperature ranging from 25 to 160°C.

7. The method according to claim 1, in which the specified device, filtration under pressure contains at least one cell of the filter, and where at least one cell of the filter accumulates at least 0.25 inch in depth specified in the filtered product.

8. The method according to claim 1, in which the specified device, filtration under pressure contains at least one cell of the filter, and where at least one cell of the filter accumulates at least 0.5 inch depth specified in the filtered product.

9. The method according to claim 1, in which the specified device, filtration under pressure contains at least one cell of the filter, and where at least one cell of the filter accumulates at least 1 inch in depth specified in the filtered product.

10. The method according to claims 7, 8 or 9 which includes the supplied washing substances form the tank above the specified filtered product that is at least 0.25 inch in depth.

11. The method according to claims 7, 8 or 9, in which the specified rotary device filtering under pressure operates at a temperature ranging from 25 to 160°C.

12. The method according to claim 11, in which the specified device filtering under d is a pressure operates at a pressure of from 1 to 50 ATM.

13. The method according to claim 11, in which the indicated dehydration results in the specified dehydrated filtered product having a moisture content of from 10 to 50%.

14. The method according to claim 6, 7 or 8, in which the specified device, filtration under pressure is a rotary drum filter high pressure.

15. The method of extraction of the metal catalyst from the oxidized waste stream of mother liquor obtained in the production of terephthalic acid, where the method includes:
(a) evaporation of the specified oxidized stream discharge, containing terephthalic acid, the specified metal catalyst, impurities, water and a solvent, in the first zone of the evaporator, to obtain the flow of steam and a concentrated suspension flow discharge;
(b) evaporating the specified concentrated suspension flow discharge in the second zone of the evaporator, with the formation of a stream enriched solvent, and a highly concentrated suspension flow discharge, where from 75 to 99 wt.% the specified solvent and water summarily removed by evaporation from the specified oxidized stream reset at stage (a) and (b);
(c) filtering the concentrated suspension flow discharge in the zone of separation of solids and liquids with the formation of the filtered product and the mother liquor;
(d) prom the internals of the specified filtered product using the supplied washing substances in a specified zone of separation of solids and liquids with the formation of the washed filtered product and the wash filtrate; and dehydration specified filtered product in a specified zone of separation of solids and liquids with the formation of dehydrated filtered product; where the specified zone separating solids and liquids includes at least one device filtering under pressure, where the specified device, filtration under pressure operates at a pressure of from 1 to 50 atmospheres;
(e) mixing in the zone of mixing water and, optionally, the extraction solvent with the specified uterine fluid and with all these wash filtrate or his part with the formation of the aqueous mixture;
(f) bringing into contact of the extraction solvent with the specified water mixture in the zone of extraction with the formation of flow of the extract and purified stream, where the specified metal catalyst is extracted from the indicated purified stream; and
(d) separation of the specified extract stream in the separation zone with the formation of the flow of organic impurities with high boiling point and flow extracted extraction solvent.

16. The method according to item 15, in which 85 to 99 wt.% the specified solvent and water summarily removed from the specified oxidized stream reset at stage (a) and phase (b).

17. The method according to item 15, in which from 90 to 99 wt.% the specified solvent and water summarily removed from the specified ocil the spent stream reset at stage (a) and phase (b).

18. The method according to clause 15 which includes the supplied washing substances added to the indicated zone separating solids and liquids in the temperature range from 20 to 100°C.

19. The method according to clause 15 which includes the supplied washing substances added to the indicated zone separating solids and liquids in the temperature range from 30 to 50°C.

20. The method according to item 15, in which the specified area extracting contains a counter-current extractor, liquid-liquid.

21. The method according to item 15, in which the specified area extracting contains a single-stage extractor, liquid-liquid.

22. The method according to item 15, wherein said extract stream contains a solvent selected from the group consisting of p-xylene, n-propyl, isopropylacetate, isobutylacetate, sec-butyl acetate, ethyl acetate and n-butyl acetate.

23. The method according to item 15, in which the second specified area of the evaporator includes an evaporator operating at a temperature of from 20 to 70°C.

24. The method according to item 15, wherein said evaporator is operated under vacuum.

25. The method according to item 15, in which the second specified area of the evaporator includes an evaporator, which operates under vacuum conditions.

26. The method according to item 15, in which the specified device, filtration under pressure operates at a temperature ranging from 25 to 160°C.

27. The method according to clause 15, which shows the device filtration under pressure contains, at least one cell of the filter, and where at least one cell of the filter accumulates at least 0.25 inch in depth specified in the filtered product.

28. The method according to item 15, in which the specified device, filtration under pressure contains at least one cell of the filter, and where at least one cell of the filter accumulates at least 0.5 inch depth specified in the filtered product.

29. The method according to item 15, in which the specified device, filtration under pressure contains at least one cell of the filter, and where at least one cell of the filter accumulates at least 1 inch in depth specified in the filtered product.

30. The method according to PP, 28 or 29 which includes the supplied washing substances form the tank above the specified filtered material which is at least 0.25 inch in depth.

31. The method according to PP, 28 or 29, in which the specified rotary device filtering under pressure operates at a temperature ranging from 25 to 160°C.

32. The method according to p in which the specified device, filtration under pressure operates at a pressure of from 1 to 50 ATM.

33. The method according to p in which the specified drying results in the specified dehydrated filtered product having a moisture content of from 10 to 50%.

34. The method according to PP, 27, 28 or 29, in which the specified device, filtration under pressure is a rotary drum filter high pressure.

35. The method according to clause 34, wherein said rotary drum filter high pressure operates at a pressure of from 1 to 5 ATM.

36. The method according to claim 1 or 15, in which the specified leaching is countercurrent.



 

Same patents:

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 121°C to 205°C 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 8.96·105 to 14.8·105 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 175°C to 216°C 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 11.7·105 to 16.2·105 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 50°C to 250°C 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: carbon materials and hydrogenation-dehydrogenation catalysts.

SUBSTANCE: invention relates to improved crude terephthalic acid purification process via catalyzed hydrogenating additional treatment effected on catalyst material, which contains at least one hydrogenation metal deposited on carbonaceous support, namely plane-shaped carbonaceous fibers in the form of woven, knitted, tricot, and/or felt mixture or in the form of parallel fibers or ribbons, plane-shaped material having at least two opposite edges, by means of which catalyst material is secured in reactor so ensuring stability of its shape. Catalyst can also be monolithic and contain at least one catalyst material, from which at least one is hydrogenation metal deposited on carbonaceous fibers and at least one non-catalyst material and, bound to it, supporting or backbone member. Invention also relates to monolithic catalyst serving to purify crude terephthalic acid, comprising at least one catalyst material, which contains at least one hydrogenation metal deposited on carbonaceous fibers and at least one, bound to it, supporting or backbone member, which mechanically supports catalyst material and holds it in monolithic state.

EFFECT: increased mechanical strength and abrasion resistance.

8 cl, 4 ex

FIELD: chemical industry; methods of production of the purified crystalline terephthalic acid.

SUBSTANCE: the invention is pertaining to the improved method of production and separation of the crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid. The method provides for the following stages: (1) loading of (i) para- xylene, (ii) the water reactionary acetic-acidic medium containing the resolved in it components of the oxidation catalyst, and (iii) the gas containing oxygen fed under pressure in the first zone of oxidation, in which the liquid-phase exothermal oxidization of the para-xylene takes place, in which the temperature and the pressure inside the first being under pressure reactor of the oxidization are maintained at from 150°С up to 180°С and from 3.5 up to 13 absolute bars; (2) removal from the reactor upper part of the steam containing the evaporated reactionary acetic-acidic medium and the gas depleted by the oxygen including carbon dioxide, the inertial components and less than 9 volumetric percents of oxygen in terms of the non-condensable components of the steam; (3) removal from the lower part of the first reactor of the oxidized product including (i) the solid and dissolved terephthalic acid and (ii) the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (4) loading of (i) the oxidized product from the stage (3) and (ii) the gas containing oxygen, into the second being under pressure zone of the oxidation in which the liquid-phase exothermal oxidization of the products of the non-complete oxidization takes place; at that the temperature and the pressure in the second being under pressure reactor of the oxidization are maintained from 185°С up to 230°С and from 4.5 up to 18.3 absolute bar; (5) removal from the upper part of the second steam reactor containing the evaporated water reactionary acetic-acidic medium and gas depleted by the oxygen, including carbon dioxide, the inertial components and less, than 5 volumetric percents of oxygen in terms of the non-condensable components of the steam; (6) removal from the lower part of the second reactor of the second oxidized product including (i) the solid and dissolved terephthalic acid and the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (7) separation of the terephthalic acid from (ii) the water reactionary acetic-acidic medium of the stage (6) for production the terephthalic acid containing less than 900 mass ppm of 4- carboxybenzaldehyde and the p-toluene acid; (8) dissolution of the terephthalic acid gained at the stage (7) in the water for formation of the solution containing from 10 up to 35 mass % of the dissolved terephthalic acid containing less than 900 mass ppm of the 4- carboxybenzaldehyde and the p-toluene acid in respect to the mass of the present terephthalic acid at the temperature from 260°С up to 320°С and the pressure sufficient for maintaining the solution in the liquid phase and introduction of the solution in contact with hydrogen at presence of the catalytic agent of hydrogenation with production of the solution of the hydrogenated product; (9) loading of the solution of the stage (8) into the crystallization zone including the set of the connected in series crystallizers, in which the solution is subjected to the evaporating cooling with the controlled velocity using the significant drop of the temperature and the pressure for initiation of the crystallization process of the terephthalic acid, at the pressure of the solution in the end of the zone of the crystallization is atmospheric or below; (10) conduct condensation of the dissolvent evaporated from the crystallizers and guide the condensed dissolvent back into the zone of the crystallization by feeding the part of the condensed dissolvent in the line of removal of the product of the crystallizer, from which the dissolvent is removed in the form of the vapor; and (11) conduct separation of the solid crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid by separation of the solid material from the liquid under the atmospheric pressure. The method allows to obtain the target product in the improved crystalline form.

EFFECT: the invention ensures production of the target product in the improved crystalline form.

8 cl, 3 tbl, 2 dwg, 3 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for isolating crystalline terephthalic acid comprising less 150 mas. p. p. per million (ppm) of p-toluic acid with respect to weight of terephthalic acid. Method involves the following steps: (1) preparing a solution containing from 10 to 35 wt.-% of dissolved terephthalic acid wherein from 150 to 1100 ppm of p-toluic acid is dissolved with respect to mass of terephthalic acid at temperature from 260°C to 320°C and under pressure providing maintaining the solution in liquid phase; (2) charge of solution from step (1) to crystallization zone comprising multitude amount of associated crystallizers wherein the solution is subjected for cooling at evaporation at the controlled rate by the moderate pressure and temperature reducing resulting to crystallization of terephthalic acid and wherein the solution pressure at the end of crystallization zone is equal to atmosphere pressure or lower; (3) condensation of solvent evaporated from crystallizers and recovering the condensed solution to the crystallization zone to place of descending flow from crystallizer wherein solvent is removed by evaporation, and (4) isolation of solid crystalline terephthalic acid comprising less 150 ppm of p-toluic acid with respect to the terephthalic acid mass by separation of the phase liquid-solid substance under atmosphere pressure. The advantage of method is preparing the end product in improved crystalline form and carrying out the process under atmosphere pressure or pressure near to atmosphere pressure.

EFFECT: improved method of crystallization.

3 cl, 1 dwg, 1 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of separating a mixture of naphthenic acids. The method is characterised by that, an aqueous solution a mixture of sodium salts of naphthenic acids - naphthenic soap, with concentration of 3 to 5 M is treated with 3 to 5 M sulphuric acid with control of the pH of the medium. For each unit change of pH value, the precipitated complex of naphthenic acid and its sodium salt is separated from the reaction mass, after which each fraction of the product is dissolved in a fivefold amount of water to decompose the formed complex, and then treated with 3 to 5 M sulphuric acid to pH 1-2 and naphthenic acids are separated from the aqueous solution to obtain fractions of naphthenic acids with dissociation constant pKa=8±1.

EFFECT: formation of complexes of naphthenic acids with their sodium salts for separation of a mixture of naphthenic acids with similar chemical and physicochemical properties.

1 ex

FIELD: chemistry.

SUBSTANCE: crystalline calcium salt of gluconic acid or its compound with excipients is processed in grinding activator devices, or to a value of supplied specific energy of not more than 10.4 kJ/g and achieving amorphous-crystalline state, or to a value of specific energy of not less than 10.5 kJ/g and achieving amorphous state. The obtained substances are analysed using X-ray diffraction, infrared, NMR, EPR spectroscopy, mass- and chromatography-mass spectrometry and differential thermal analysis.

EFFECT: mechano-activated amorphous and amorphous-crystalline compounds and compositions are used as active compounds for making pharmaceutical preparations.

13 cl, 10 dwg, 12 ex

FIELD: chemistry.

SUBSTANCE: sodium hydroxide solution is added to a technical mixture of benzoic and cinnamylic acid, obtaining a precipitate. Water is added to obtain a homogeneous solution. The obtained technical mixture of sodium salts of benzoic and cinnamylic acid with composition ranging from 2:1 to 1:2 and overall concentration ranging from 3 to 5 M is then mixed with sulphuric acid with concentration ranging from 3 to 5 M. Addition of sulphuric acid is stopped at pH of the medium between 8 and 9, and the precipitated complex of cinnamylic acid with its sodium salt is filtered from the reaction mixture, dissolved in excess amount of water to dissolve sodium salt of cinnamylic acid. Cinnamylic acid precipitates, and is further treated with sulphuric acid with concentration ranging from 3 to 5 M to pH between 1 and 2. The precipitated crystals of cinnamylic acid are separated; the reaction mixture remaining after separation of the complex is mixed with a solution of sulphuric acid with concentration ranging from 3 to 5 M until pH between 1 and 2. As a result, crystalline benzoic acid forms.

EFFECT: formation of complexes of carboxylic acids with their sodium salts for separating components of a mixture of carboxylic acids with similar chemical and physico-chemical properties.

2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a thermal separation method using fractional condensation of a product-gas mixture, obtained through heterogeneous catalysed partial oxidation of propene and/or propane in gaseous phase to acrylic acid, for separating at least one mass flow, concentrated with acrylic acid, from a product-gas mixture containing acrylic acid, which involves continuous static operation of at least one device for thermal separation, containing at least one effective separation chamber with a fractionation column which has mass-transfer trays as built-in separating elements, in which the product-gas mixture is loaded, containing acrylic acid as at least one mass flow, and from which at least one mass flow containing acrylic acid is unloaded under the condition that, the overall mass flow loaded into the effective separation chamber and obtained from combining separate mass flows loaded into the separating chamber, contains X wt % components distinct from acrylic acid, the mass flow which is unloaded from the effective separation chamber with the largest content of acrylic acid, contains Y wt % components distinct from acrylic acid, ratio X:Y is ≥5, effective separation chamber, except the loading and unloading place, is bordered by a solid phase and contains, besides the mass-exchange trays as built-in separating elements in the fractionation column, at least one circulating heat exchanger, and total volume of the chamber, filled with liquid phase, is ≥1 m3, wherein temperature of the liquid phase is at least partially ≥80°C, when the effective separation chamber is divided into n separate volume elements, wherein the highest and lowest temperature of liquid phase in a separate volume element differ by not more than 2°C, and the volume element in the effective separation chamber is solid, total dwell time ttotal.

≤20 h, where A = (Ti-To)/10°C, To= 100°C, Ti = arithmetic mean value of the highest and lowest temperature of the ith volume element in the liquid phase in °C, msi = total mass of acrylic acid in the volume of the liquid phase of the ith volume element, mi = total liquid phase mass unloaded from the ith volume element, and is the sum of all volume elements i, under the condition that, volume elements i with liquid phase mass mi and as volume elements with a dead zone are also not included in the sum of all volume elements i, as well as volume elements i, which do not contain liquid phase, and total amount of liquid phase contained in volume elements with a dead zone is not more than 5 wt % of the total amount of liquid phase contained in the effective separation chamber.

EFFECT: separation of mass flow concentrated with acrylic acid.

10 cl, 12 dwg, 2 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: proposal is given of a method of removing impurities from a water mixture or purified water mixture through extraction of the water mixture or purified water mixture using an extractive solvent in the extraction zone with formation of a stream of extract and a stream of raffinate and, optionally, separation of the extract stream and the solvent rich stream in the separation zone with formation of a stream of organic impurities with high boiling point and a stream of extractive solvent.

EFFECT: provision for extracting metallic catalyst in active form, reusable at the paraxylene recycling stage.

29 cl, 2 dwg, 1 tbl

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: method of separating multi-atom alcohols, for instance, neopentylglycol and sodium formiate, includes evaporation and cooling of reaction mixture, addition of organic solvent, crystallisation of sodium formiate, separation of sodium formiate from saturated solution of multi-atom alcohol, for instance, by filtration, and crystallisation of multi-atom alcohol. Reaction mixture is evaporated until two liquid layers are formed, which are separated into light phase - water-multi-atom alcohol and heavy phase -water-salt, separated water-salt fraction of solution is cooled until sodium formiate contained in it in form of cryslallohydrate is crystallised, sodium formiate crystals are separated, and remaining mother-solution is returned to process head, to evaporation stage, then separated light phase - water-multi-atom alcohol is additionally evaporated until 70% of contained in it sodium formiate is crystallised, then cooled to 25-30°C and subjected to processing with organic solvent from line of single-atom saturated alcohols, for instance, methane, for removal of remaining admixtures, with further crystallisation of multi-atom alcohol from remaining mother-solution.

EFFECT: reduction of amount of used organic solvent, elimination of high-temperature stage of extraction, preservation of yield of pure target products.

2 cl, 2 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: chemical industry; methods of production of the purified crystalline terephthalic acid.

SUBSTANCE: the invention is pertaining to the improved method of production and separation of the crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid. The method provides for the following stages: (1) loading of (i) para- xylene, (ii) the water reactionary acetic-acidic medium containing the resolved in it components of the oxidation catalyst, and (iii) the gas containing oxygen fed under pressure in the first zone of oxidation, in which the liquid-phase exothermal oxidization of the para-xylene takes place, in which the temperature and the pressure inside the first being under pressure reactor of the oxidization are maintained at from 150°С up to 180°С and from 3.5 up to 13 absolute bars; (2) removal from the reactor upper part of the steam containing the evaporated reactionary acetic-acidic medium and the gas depleted by the oxygen including carbon dioxide, the inertial components and less than 9 volumetric percents of oxygen in terms of the non-condensable components of the steam; (3) removal from the lower part of the first reactor of the oxidized product including (i) the solid and dissolved terephthalic acid and (ii) the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (4) loading of (i) the oxidized product from the stage (3) and (ii) the gas containing oxygen, into the second being under pressure zone of the oxidation in which the liquid-phase exothermal oxidization of the products of the non-complete oxidization takes place; at that the temperature and the pressure in the second being under pressure reactor of the oxidization are maintained from 185°С up to 230°С and from 4.5 up to 18.3 absolute bar; (5) removal from the upper part of the second steam reactor containing the evaporated water reactionary acetic-acidic medium and gas depleted by the oxygen, including carbon dioxide, the inertial components and less, than 5 volumetric percents of oxygen in terms of the non-condensable components of the steam; (6) removal from the lower part of the second reactor of the second oxidized product including (i) the solid and dissolved terephthalic acid and the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (7) separation of the terephthalic acid from (ii) the water reactionary acetic-acidic medium of the stage (6) for production the terephthalic acid containing less than 900 mass ppm of 4- carboxybenzaldehyde and the p-toluene acid; (8) dissolution of the terephthalic acid gained at the stage (7) in the water for formation of the solution containing from 10 up to 35 mass % of the dissolved terephthalic acid containing less than 900 mass ppm of the 4- carboxybenzaldehyde and the p-toluene acid in respect to the mass of the present terephthalic acid at the temperature from 260°С up to 320°С and the pressure sufficient for maintaining the solution in the liquid phase and introduction of the solution in contact with hydrogen at presence of the catalytic agent of hydrogenation with production of the solution of the hydrogenated product; (9) loading of the solution of the stage (8) into the crystallization zone including the set of the connected in series crystallizers, in which the solution is subjected to the evaporating cooling with the controlled velocity using the significant drop of the temperature and the pressure for initiation of the crystallization process of the terephthalic acid, at the pressure of the solution in the end of the zone of the crystallization is atmospheric or below; (10) conduct condensation of the dissolvent evaporated from the crystallizers and guide the condensed dissolvent back into the zone of the crystallization by feeding the part of the condensed dissolvent in the line of removal of the product of the crystallizer, from which the dissolvent is removed in the form of the vapor; and (11) conduct separation of the solid crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid by separation of the solid material from the liquid under the atmospheric pressure. The method allows to obtain the target product in the improved crystalline form.

EFFECT: the invention ensures production of the target product in the improved crystalline form.

8 cl, 3 tbl, 2 dwg, 3 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

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