Method of purification of raw carboxylic acid suspension

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

 

The technical field to which the invention relates

The present invention relates to a cleaning method of a suspension of the crude carboxylic acid. More specifically, the present invention relates to a cleaning method of a suspension of the crude carboxylic acid by use of the separation zone of solid food and liquid between the area of the primary oxidation zone and the subsequent oxidation.

The level of technology

Terephthalic acid is produced commercially by the 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 that are present due to the oxidation of paraxylene. In a typical industrial process to produce crude terephthalic acid, then dissolved solid crude terephthalic acid in water at high temperatures and pressures, hydronaut the resulting solution, cooled and crystallized product of terephthalic acid from the solution, and separating the product in the form of solid terephthalic acid from the liquid, as described in U.S. patent No. 3584039, which is included here by reference.

Developed and is commercially available a number of methods for the production of solid purified teret the left acids. Usually purified terephthalic acid produced in the form of a solid product in a multistage process, in which receive the crude terephthalic acid. Crude terephthalic acid is not of sufficient quality for direct use as source material for industrial polyethylene terephthalate (PET). Instead, the crude terephthalic acid is usually processed to solid purified terephthalic acid.

Liquid-phase oxidation of p-xylene gives the crude terephthalic acid. Crude terephthalic acid is dissolved in water and hydronaut to transform 4-carboxybenzene in p-Truelove acid, which is a more soluble derivative, and with the aim of turning compounds are characterized by yellow to colorless derivatives. A significant number of 4-carboxybenzene and p-Truelove acid in the final purified product of terephthalic acid are particularly harmful for polymerization processes, as they can act as circuit breakers during the condensation reaction between terephthalic acid and ethylene glycol in the production of PET. Typical purified terephthalic acid contains, by weight, less than 250 ppm (ppm) 4-carboxybenzene and less than 150 ppm p-Truelove acid.

Crude terephthalic sour is and usually contains, by weight, from about 800 to 7000 ppm (ppm) 4-carboxybenzene and from about 200 to 1500 ppm p-Truelove acid, as the main impurities. Crude terephthalic acid also contains smaller amounts, in the range of about 20-200 ppm, aromatic compounds having a structure derived from benzyl, fluorenone and/or anthraquinone, which are compounds characteristic yellow color, as impurities resulting from adverse reactions linking occurring during the oxidation of p-xylene.

This cleaning usually involves adding water to the crude terephthalic acid, with the formation of a slurry of crude terephthalic acid, which is heated to dissolve the crude terephthalic acid. Then a solution of crude terephthalic acid is passed into the reactor, in which the solution comes into contact with hydrogen in the presence of a heterogeneous catalyst, at temperatures of from about 200° up to about 375°C. This stage of recovery turns a different color-forming compounds present in the crude terephthalic acid, colorless derivatives. The main impurity - 4-carboxybenzene turns into p-Truelove acid.

Typical crude terephthalic acid contains excessive amounts, by weight, as a 4-carboxybenzene and p-t is luilui acid. For this reason, receiving less than 250 mass ppm 4-carboxybenzene and less than 150 mass ppm p-Truelove acid in purified terephthalic acid mechanisms are required for the purification of crude terephthalic acid and removal of impurities.

In many processes painted impurities hydronauts to colorless derivatives and leave the process together with the solid product of terephthalic acid and wastewater flows. However, one of the embodiments of the present invention provides an attractive method for the production of suspensions of purified carboxylic acid by use of the separation zone of solid foods and liquids containing solids separator and the liquid, after oxidation product slurry of crude carboxylic acid and before final filtration and drying, without the use of stage hydrogenation.

The invention

In one of the embodiments of the present invention provides a method of production of a product is purified carboxylic acid without the use of hydrogenation of terephthalic acid or way of separating impurities oxidizing solvent, as described in U.S. patent No. 3584039.

In another embodiment, the present invention provides a method of production of the product in suspension. The method includes the impact of the removal of impurities from a suspension of the crude carboxylic acid in the zone of separation of solids and liquids with the formation of the product in suspension.

In another embodiment, the present invention provides a method of production of a product is purified carboxylic acid. The method includes:

(a) removing impurities from a suspension of the crude carboxylic acid in the zone of separation of solids and liquids with the formation of the product slurry;

(b) the oxidation product slurry in the zone of subsequent oxidation with the formation of the product subsequent oxidation;

(c) crystallization of the product subsequent oxidation in the crystallization zone with the formation of the crystallized product.

In another embodiment, the present invention provides a production method of a suspension of purified carboxylic acid. The method includes:

(a) removing impurities from a suspension of the crude carboxylic acid in the zone of separation of solids and liquids with the formation of the product is a suspension, where the suspension of the crude carboxylic acid includes terephthalic acid, catalyst, acetic acid and impurities, which are allocated at a temperature in the range of about between 140°C and approximately 170°C, from the oxidation of paraxylene in the area of primary oxidation;

(b) the oxidation product slurry in the zone of subsequent oxidation with the formation of the product subsequent oxidation; wherein the oxidation is carried out at a temperature within the range of the x between about 190° C and about 280°C; and in which the oxidation zone subsequent oxidation occurs at a temperature higher than in the area of primary oxidation;

(c) crystallization of the product subsequent oxidation in the crystallization zone with the formation of the crystallized product;

(d) cooling the crystallized product in the cooling zone with the formation of a chilled suspension of purified carboxylic acid; and

(e) filtering and optionally drying the cooled suspension of the purified carboxylic acid in the area of filtration and drying, to remove part of the solvent from the cooled suspension of carboxylic acid with the product is purified carboxylic acid.

In another embodiment, the present invention provides a method of production of a product is purified carboxylic acid. The method includes:

(a) oxidation of aromatic starting materials in the area of primary oxidation with formation of a suspension of the crude carboxylic acid; where the suspension of the crude carboxylic acid includes terephthalic acid; where the oxidation is carried out at a temperature in the range of from about 120°C to about 190°C;

(b) removing impurities from a suspension of the crude carboxylic acid in the zone of separation of solids and liquids with the formation of the product is a suspension, where the suspension of raw carbon is Oh acid includes terephthalic acid, the catalyst, acetic acid and impurities, which are discharged at a temperature of between about 140°C and approximately 170°C, from the oxidation of paraxylene in the area of primary oxidation;

(c) oxidation product slurry in the zone of subsequent oxidation with the formation of the product subsequent oxidation; where the oxidation is carried out at a temperature in the range from about 190°C to about 280°C; and where the oxidation occurs at a temperature in the zone of subsequent oxidation, higher than in the area of primary oxidation;

(d) crystallization of the product subsequent oxidation in the crystallization zone with the formation of the crystallized product;

(e) cooling the crystallized product in the cooling zone with the formation of a chilled suspension of purified carboxylic acid; and

(f) filtering and optionally drying the cooled suspension of the purified carboxylic acid in the area of filtration and drying, to remove part of the solvent from the cooled suspension of carboxylic acid, the product is purified carboxylic acid.

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

Brief description of drawings

The figure represents a diagram of the method according to the present invention for the oxidative purification of carboxylic sour is s, in which area 40 separation of solids and liquids is used between the primary oxidation zone 20 and zone 80 subsequent oxidation.

Detailed description of the invention

The present invention provides the purification method of the suspension 30 crude carboxylic acid. The method includes the stage of selection of mother liquor from the slurry of the crude carboxylic acid in the area of 40 separation of solids and liquids with the formation of product 70 suspension.

Crude terephthalic acid is conveniently get through liquid-phase oxidation of paraxylene in the air, in the presence of an appropriate oxidizing catalyst. Usable catalysts include at least one catalyst selected, but not limited to compounds of cobalt, bromine and manganese, which are soluble in the selected solvent. Usable solvents include, but without limitation specified, aliphatic monocarboxylic acids, preferably containing from 2 to 6 carbon atoms, or benzoic acid, and mixtures thereof, 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 present description, the vinegar is Aya 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. Patents describing the production of terephthalic acid, such as U.S. patent No. 4158738 and No. 3996271, are included here as reference.

In one of the embodiments of the present invention a method for the production of the product 70 in the form of suspension is given on the drawing. The method includes the removal of impurities from the suspension 30 crude carboxylic acid in the area of 40 separation of solids and liquids with the formation of product 70 in the form of a suspension; where the product 70 suspension is formed without phase hydrogenation.

Area 40 separation of solids and liquids, impurities, suspension 30 crude carboxylic acid and the product 70 in the form of a suspension, all described later in this description.

In another embodiment of the present invention in the drawing provides a method for the production of the product 230 - purified carboxylic acid. The method includes the following steps.

Stage (a) includes the removal of impurities from the suspension 30 crude carboxylic acid in the area of 40 separation of solids and liquids with the formation of product 70 in the form of a suspension.

Suspension 30 crude carboxylic acid contains at least one carboxylic acid, the catalyst is ENISA least one solvent and impurities are removed through line 30.

Impurities typically include at least one or more of the following compounds: 4-carboxybenzene (4-CBA), trimellitic acid (TMA) and 2,6-dicarboxylate (2,6-DCF). The solvent typically includes acetic acid, but may be any solvent, which was discussed earlier.

The suspension 30 crude carboxylic acid get through oxidation in a primary oxidation zone 20 aromatic raw materials 10. In one embodiment, the implementation of aromatic starting materials include paraxylene. The primary oxidation zone 20 contains at least one oxidation reactor, and the slurry 30 crude carboxylic acid contains at least one carboxylic acid. The oxidation reactor can be operated at temperatures ranging from about 120°C to about 200°C, preferably from about 140°C to approximately 170°C. typically, aromatic raw materials 10 are paraxylene, and the carboxylic acid is a terephthalic acid. In one of the embodiments of the present invention, the area of primary oxidation contains a bubble column.

For this reason, when using terephthalic acid slurry 30 crude carboxylic acid Boo who should be referred to as a slurry of crude terephthalic acid, and the product 230 - purified carboxylic acid should be referred to as the product is purified 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. Suitable examples of such aromatic rings include, but are not limited to, benzene, biphenyl, terphenyl, naphthalene, and other condensed aromatic ring carbon-based. Examples of usable carboxylic acids include, but are not limited to, terephthalic acid, benzoic acid, p-Truelove, isophthalic acid, trimellitic acid, naphthaleneboronic acid and 2,5-diphenyl-terephthalic acid. Can be any of the embodiments of the present invention, in which essentially no terephthalic acid and isophthalic acid in a suspension of the crude carboxylic acid. When using the term "essentially no", it means the number is STV less than 5% of the mass.

The slurry of crude terephthalic acid conveniently synthesized by liquid phase oxidation of paraxylene in the presence of an appropriate oxidizing catalyst. Suitable catalysts include, but are not limited to, compounds of cobalt, manganese and bromine, which are soluble in the selected solvent. In one of the embodiments of the present invention, the catalyst contains cobalt, bromine and manganese. Cobalt and manganese, taken together, may be in a suspension of the crude carboxylic acid at concentrations of from about 150 ppm to about 3200 ppm mass. Bromine may be in suspension of the crude carboxylic acid at concentrations of from about 10 ppm to about 5000 ppm, mass. Preferably, cobalt and manganese, taken together, may be in a suspension of the crude carboxylic acid at concentrations of from about 1050 ppm to about 2700 ppm mass. Bromine may be in suspension of the crude carboxylic acid at concentrations of from about 1000 ppm to about 2500 ppm of the mass.

A suspension of crude carboxylic acid in conduit 30 is injected into an area of 40 separation of solids and liquids capable of removing part of the liquid contained in the suspension 30 crude carboxylic acid, to obtain the product slurry in the pipeline 70. "Part" means that the power is raised, at least 5 wt.% the fluid. Removal of part of the liquid product slurry in the pipe 70 may be any means known in the field. Typically, the area of 40 separation of solids and liquids contains a separator for solids and liquids, which are selected from the group consisting of decantorului centrifuges, rotary disk centrifuges, belt filter, rotary vacuum filter, and the like. A suspension of crude carboxylic acid in the pipeline 30 is introduced into zone 40 separation of solid foods and liquids containing separator for solids and liquids. Separator for solid foods and liquids operates at temperatures in the range between about 50°C and about 200°C, preferably from 140°C approximately 170°C. a Separator for solids and liquids operates at pressures between about 30 psi and about 200 psi. Separator for solid foods and liquids in the area of 40 separation of solids and liquids can operate in continuous or batch mode, although it will be clear that for industrial processes continuous mode is preferred.

Impurities in the mother liquor is removed from the zone 40 separation of solids and liquids, and to divert through the line 60. One option is to implement the present invention in the area of 40 separation of solid food and liquids enter additional solvent through line 50, for re-suspension suspension 30 crude carboxylic acid and the formation of product 70 in the form of a suspension. Uterine fluid 60 is removed from the zone 40 separation of solid food and liquid through the line 60, and it contains a solvent, typically acetic acid, the catalyst and bromine compounds. Uterine fluid in line 60 can be either directed to a process for separating impurities from oxidizing solvent through lines, not shown, or recycled in the system of the catalysts by means of lines which are not shown. One of the technologies to remove impurities from the mother liquor, 60, widely used in the chemical processing industry, is to extract or "cleaning up" some portion of the recirculated flow. Typically, the purified stream simply replace or if it is economically justified, subjected to different types of processing to remove undesirable impurities, removing at the same time valuable components. Examples of methods for removing impurities include U.S. patent No. 4939297 and U.S. patent No. 4356319 included here as a reference.

Stage (b)comprising the oxidation product 70 in the form of a suspension in the zone of 80 subsequent oxidation with the formation of the product 110 subsequent oxidation.

In one of the embodiments of the present invention the product of the 70 suspension divert through the line 70 in an area of 80 subsequent oxidation, where it is heated to a temperature in the range between about 190°C and about 280°C, and preferably between about 200°C and about 250°C, and optionally oxidized with air introduced through line 100, to obtain the product 110 subsequent oxidation.

Area 80 subsequent (additional) oxidation contains at least one tank reactor subsequent oxidation. The product 70 in the form of a suspension is introduced into an area of 80 subsequent oxidation. The term "post-oxidation" means that the oxidation is carried out in the area of 20 primary oxidation discussed earlier, and in the zone of 80 subsequent oxidation. For example, the area of 80 subsequent oxidation may contain the serial number of reactor vessels subsequent stages of oxidation.

When the carboxylic acid is a terephthalic acid, an area of 80 subsequent oxidation contains the oxidation reactor, which is heated to a temperature in the range between about 190°C and about 280°C, preferably between about 200°C and about 250°C, and most preferably between 205°C and 225°C, and conduct additional oxidation with air or other source of molecular oxygen introduced through line 100, to obtain the product 110 subsequent oxidation. Typically, the oxidation zone 80 posleduyuschiey occurs when the temperature is higher, what is the oxidation zone 20 primary oxidation, to improve the removal of impurities. Area 80 subsequent oxidation can be heated directly, using solvent vapor or water vapor through pipe 90 or indirectly, by any means known in this field. Cleaning in the area subsequent oxidation occurs through a mechanism associated with recrystallization or crystal growth and oxidation of impurities.

Additional air or molecular oxygen can be introduced into an area of 80 subsequent oxidation through line 100, in an amount necessary to oxidize a sufficient part of the partially oxidized products such as 4-carboxyaldehyde (4-CBA), in suspension 30 crude carboxylic acid or in the product 70 in the form of a suspension, to the corresponding carboxylic acid. Typically, at least 70% of the mass of the 4-CBA converted into terephthalic acid in the zone of 80 subsequent oxidation. Preferably, at least 80% of the mass of the 4-CBA converted into terephthalic acid in the zone of 80 subsequent oxidation. Significant concentrations of 4-carboxybenzene and p-Truelove acid in the product of terephthalic acid are particularly harmful to the polymerization process, as they can act as circuit breakers during the condensation reaction between terephthalonitrile and ethylene glycol, upon receipt of polyethylenterephtalate (PET). A typical product of terephthalic acid contains, by weight, less than about 250 ppm (ppm) 4-carboxyaldehyde and less than about 150 ppm p-Truelove acid.

Impurities in suspension 30 crude carboxylic acid or product 70 suspension into solution when the particles of terephthalic acid dissolved and precrystallization in the zone of 80 subsequent oxidation. The exhaust gas from the zone of 80 subsequent oxidation is removed through line 105 and introduced into the extraction system, where the exhaust gas containing volatile organic compounds (VOC), remove the solvent. VOC containing methyl bromide, can be processed, for example by combustion in the catalytic oxidation. Product 110 subsequent oxidation zone 80 subsequent oxidation is removed through line 110.

Stage (c) comprises crystallization of the product 110 subsequent oxidation zone 120 crystallization, to obtain the crystallized product 160. Typically, the area 120 crystallization contains at least one mold. Vaporous product from the crystallization zone may condense at least one condenser and returned to the crystallization zone. Optionally, the liquid from the condenser or vaporous product from the zone of crystallizatio what can be recycled, or it can be retrieved or sent to the device to extract energy. In addition, the exhaust gas from the mold is removed through line 170, and can be sent to the extraction system, where the solvent is removed, and the exhaust gas from the mold containing VOC, can be processed, for example by incineration, catalytic oxidation.

When the carboxylic acid is a terephthalic acid product 110 subsequent oxidation zone 80 subsequent oxidation is removed through line 110 and is introduced into the area 120 of crystallization containing at least one crystallizer where it is cooled to a temperature in the range of about between 110°C and about 190°C with the formation of the crystallized product 160, preferably, to a temperature in the range of about between 140°C and about 180°C, most preferably from about 150°C approximately 170°C.

Crystallized product 160 from the zone 120 of crystallization is removed through line 160. As a rule, the crystallized product 160 is then injected directly into a container and cooled with the formation of a chilled suspension 210 purified carboxylic acid. When the carboxylic acid is a terephthalic acid, a cooled suspension 210 crystallized purified carboxylic acid of laidout in the vessel, as a rule, to a temperature of about 90°C or less, before the introduction of the process for extraction of terephthalic acid in the form of a dry powder or wet cake.

Stage (d) comprises cooling the crystallized product in the cooling zone of 200 with the formation of a chilled suspension 210 purified carboxylic acid.

Crystallized product 160 is removed from the zone 120 crystallization via line 160. Crystallized product 160 is introduced into the cooling zone of 200 and cooled to a temperature less about 90°C, with the formation of a chilled suspension 210 purified carboxylic acid. The cooled suspension of the purified carboxylic acid can be carried out by any means known in this field, as a rule, the area 200 contains cooling evaporative tank.

Stage (e) includes filtering and optionally drying the cooled suspension 210 purified carboxylic acid in the zone 220 filtering and drying, to remove part of the solvent from the cooled suspension 210 purified carboxylic acid, to obtain the product 230 - purified carboxylic acid.

The cooled suspension 210 purified carboxylic acid is removed from the zone 200 cooling and injected into an area of 220 filtration and drying. Part of the solvent and the remaining catalyst and impurities are separated, and the product purified carboxylic key is lots removed through line 230.

Area 220 filtration and drying contains a filter suitable for the extraction of solid carboxylic acids, and dryer. Filtering may be accomplished by any means known in the field. For example, filtering can be used rotary vacuum filter to obtain a filtered cake. The filtered cake passes through the initial stage of removal of the solvent, and then washed with acid wash to remove residual catalyst, and then the solvent is again removed before sending to the dryer. Drying the pellet in the filter may be accomplished by any means known in the field that can evaporate at least 10% of volatile substances remaining in the cake on the filter, obtaining the product - carboxylic acid. For example, can be used dryer Single Shaft Porcupine® Processor.

Product 230 - purified carboxylic acid has the value b*of less than about 4.5. Preferably, the color index b* of the purified carboxylic acid (product) 230 is less than about 3.5. Most preferably, the color index b* of the product 230, i.e. the purified carboxylic acid is less than about 3. Color index b* is one of the three color characteristics, as measured by spectroscopic instrument, founded the m on the measurement of the reflection coefficient. Color can be measured using any device known in this field. Measuring device, as a rule, is a tool Hunter Ultrascan XE-mode measurement of the reflection coefficient.

A positive value reported mean level of yellow (or absorption coefficient blue), while a negative value reported mean level blue (or absorption coefficient of yellow).

It should be noted that the previously described zone of the process can be used to obtain product is purified carboxylic acid in any other logical order. It should also be noted that, when the zone of the process are in a different order, process conditions can be changed.

In another embodiment, the present invention each alternative implementation may optionally contain additional stage comprising discoloration carboxylic acid or esterified carboxylic acid by hydrogenation.

Discoloration of the suspension of the purified carboxylic acid or esterified carboxylic acid can be carried out by any means known in this field, and is not limited to hydrogenation. However, for example, in one of the embodiments of the present invention, the discoloration can about usestate through interaction carboxylic acid, which was processed by esterification, for example, using ethylene glycol with molecular hydrogen in the presence of a hydrogenation catalyst, in a reactor, to obtain the solution decolorized carboxylic acid or discolored ester product. For a reactor there are no specific restrictions on its shape or design, when using patterns, which enables the supply of hydrogen in the exercise of close contact carboxylic acid or ester product with the catalyst in the reactor. Typically, the hydrogenation catalyst is typically a single metal of Group VIII or a combination of metals of Group VIII. Preferably, the catalyst is chosen from the group consisting of palladium, ruthenium, rhodium and combinations thereof. The reactor contains a hydrogenation reactor, which operates at a temperature and pressure sufficient to hydrogenation parts of the compounds are characterized by yellow to colorless derivatives.

Examples

The present invention will be further illustrated by the following further example of its preferred embodiments, although it will be understood that these examples are included only for illustration purposes and are not intended to limit the scope of the present invention, if only the SP is potentially not specified.

Example

Paraxylene oxidize at 160°C using catalytic systems Co, Mn, Br, to obtain a slurry of crude terephthalic acid having 30-35% solids. The slurry of crude terephthalic acid is crystallized and purified using the method shown in the drawing, except for the stage of hydrogenation, and the crystallized product from the zone 120 crystallization is transferred directly into the evaporation tank. The product is removed after filtration and drying and analyze 4-carboxybenzene (4-CBA), trimellitic acid (TMA) and 2,6-dicarboxylate (2,6-DCF), the transmittance and b*. b* represents one of the three color characteristics, as measured by spectroscopic tool, based on measurements of the reflection coefficient. Measuring device, as a rule, is a tool Hunter Ultrascan XE. A positive value reported mean level of yellow (or absorption coefficient blue), while registered negative values indicate the level of the blue (or the absorption coefficient of yellow).

The concentration of 4-CBA, TMA, 2,6-DCF in terephthalic acid analyzed with liquid chromatography. To determine the transmittance measured 10% solution of the product of terephthalic acid in 2M KOH, using a spectrometer in the UV and in the Dima region, at 340 nm. b* terephthalic acid was measured using the method of reflection colors at 340 nm. The results are presented in the table.

Table

Ave. No.4-CBA1(ppm)TMA2(ppm)2,6-DCF3(ppm)%T4b*5
11035110894,1

The amount of 4-CBA, present in the product purified terephthalic acid obtained by the method according to the present invention is significantly reduced compared to typical levels found in the suspension of the crude carboxylic acid. Typical levels are not measured in the present study, but these levels are known to specialists in this field and are similar to those described earlier, with the suspension of the crude carboxylic acid containing terephthalic acid, typically contains, by weight, from about 800 to 7000 ppm (ppm) 4-carboxybenzene. % bandwidth product purified terephthalic acid has a direct impact on the color of the produced polyethylene terephthalate (PET). The desired PTA (purified terephthalic acid) is a white (which is referred to as the presence of a weak staining). Higher % passing points is no more weak color PTA. The level of improvement in all measured categories is particularly unexpected, given the simplicity of centrifugation in the zone of separation of solid and liquid that stage hydrogenation is not carried out. In the past, comparable levels of purity was achieved, usually through the use of plants for the hydrogenation, which contains numerous steps and equipment, and significant investment.

The present invention is described with specific reference to its preferred options for implementation, but it will be understood that variations and modifications can be effected within the essence and scope of the present invention.

1. The method of obtaining the product is purified carboxylic acid, including:

(a) oxidation of aromatic starting materials in the area of primary oxidation with formation of a suspension of the crude carboxylic acid, where the suspension of the crude carboxylic acid includes terephthalic acid, where the aforementioned oxidation is carried out at in the range from 120 to 200°C;

(b) removing impurities from the crude suspension of carboxylic acid, designated at a temperature of from 140 to 170°With phase oxidation of paraxylene in the area of primary oxidation and containing terephthalic acid, catalyst, acetic acid and other impurities that are carried out in somerstein solids and liquids with the formation of flow of the mother liquor and the product in suspension, where part of the specified catalyst at a specified suspension of the crude carboxylic acid is removed in the specified thread uterine fluid, and where indicated zone separating solids and liquids added optional additional solvent;

(c) oxidation of the specified product in suspension in the zone of subsequent oxidation with the formation of the product subsequent oxidation, where the aforementioned oxidation is carried out at a temperature of from 190 to 280°and where the specified oxidation occurs in this zone subsequent oxidation at a temperature higher than the specified area of the primary oxidation;

(d) crystallization of the specified product subsequent oxidation in the crystallization zone with the formation of the crystallized product in the form of suspension;

(e) cooling the specified crystallized product in the form of a suspension in the cooling zone with the formation of a chilled suspension of purified carboxylic acid and

(f) filtering and optional drying specified cooled suspension of purified carboxylic acid in the area of filtration and drying to remove from the specified cooled suspension of carboxylic acid portion of the solvent to obtain the specified product is purified carboxylic acid.

2. The method according to claim 1, further comprising bleaching the decree which authorized the suspension of the purified carboxylic acid or esterified carboxylic acid in the reactor.

3. The method according to claim 2, in which the specified discoloration is implemented by engagement of the solution indicated the crude carboxylic acid with hydrogen in the presence of a hydrogenation catalyst in the reactor with getting discolored solution of carboxylic acid.

4. The method according to claim 1, in which the specified area of separation of solids and liquids contains a separator for solids and liquids, which operates at a temperature of from 50 to 200°C.

5. The method according to claim 1, wherein said product is purified suspension has the value b*of less than 4,5.

6. The method according to claim 1, wherein said catalyst contains compounds of cobalt, manganese and bromine.

7. The method according to claim 6, in which the cobalt and manganese, taken together, are present in suspension of the crude carboxylic acid in a concentration of from 1050 to 2700 ppm mass and bromine may be in suspension of the crude carboxylic acid in a concentration of from 1000 to 2500 h/million mass.

8. The method according to claim 1, in which the specified suspension of the crude carboxylic acid includes terephthalic acid.



 

Same patents:

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: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for chemical reutilization of depleted polyethylene terephthalate, especially to non-classified crumbs of utilized polyethylene terephthalate articles resulting to preparing terephthalic acid and ethylene glycol. Method involves hydrolysis of utility waste polyethylene terephthalate with aim for its depolymerization and involves the following steps: (a) separation of polyethylene terephthalate component in the parent raw by its transfer to fragile form by using crystallization, grinding and the following screening processes; (b) continuous two-step hydrolysis of polyethylene terephthalate carried out at the first step by injection of steam into polymer melt followed by carrying out the hydrolysis reaction of products from the first step with ammonium hydroxide and by the following (c) precipitation of terephthalic acid from aqueous solution of hydrolysis products from the second step with inorganic acid and separation of terephthalic acid by filtration method and by the following (d) extraction of ethylene glycol by rectifying from solution of the second step hydrolysis products after separation of terephthalic acid. This technologically simple and effective method provides possibility for treatment of very contaminated the parent raw and providing high purity of end products.

EFFECT: improved treatment method.

5 cl, 1 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a continuous method for preparing highly pure terephthalic acid. Method involves oxidation of p-xylene with oxygen-containing gas in acetic acid medium in the presence of catalyst comprising heavy metal salts, such as cobalt and manganese and halide compounds under increased pressure and temperature up to the definite degree of conversion of para-xylene to terephthalic acid at the first step and the following two-step additional oxidation of prepared reaction mixture and isolation of the end product. Mixing time of reagents is <25 s, oxidation at the first step is carried out at temperature 180-200°C up to conversion degree of p-xylene 95%, not above, oxidation at the second step is carried out at temperature 175-185°C and before feeding to the third step of oxidation the reaction mass is heated to 200-260°C, kept for 8-12 min and oxidized at temperature 180-200°C in the presence of catalyst comprising Ni and/or Zr salts additionally. As halide compounds method involves using XBr or XBr + XCl wherein X is H, Na, Li followed by isolation of solid products of oxidation after the third step and successive treatment with pure acetic acid and water in the mass ratio terephthalic acid : solvent = 1:3. Invention provides intensification of process and to enhance quality of terephthalic acid.

EFFECT: improved method for preparing.

1 tbl, 1 dwg, 14 ex

The invention relates to an improved method of reducing the content of 4-carboxybenzene in the production of terephthalic or 3-carboxymethylthio in the production of isophthalic acid, comprising: (a) dissolving crude terephthalic acid or crude isophthalic acid in a solvent at a temperature of from 50 to 250With obtaining a solution; (b) crystallization of the purified acid from this solution by reducing the temperature and/or pressure; (C) the Department specified crystallized terephthalic acid or isophthalic acid from the solution; (d) adding an oxidant to the reactor oxidation carboxyanhydride for oxidation specified filtered solution of stage (C), leading to the transformation of 4-carboxybenzene or 3-carboxymethylthio in terephthalic acid or isophthalic acid; (e) evaporating the solvent from this solution from step (d); (f) cooling the concentrated solution from step (e) for crystallization additional quantities of purified terephthalic acid or isophthalic acid and filtering the specified slurry and recycling the most part, the mother liquor from step (f) in the devices is

The invention relates to an improved process for the preparation of terephthalic and isophthalic acids

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: industrial production of methacrylic acids at reduced amount of industrial wastes.

SUBSTANCE: proposed method is performed by catalytic oxidation of propane, propylene or isobutylene in vapor phase at separation of final product and forming of high-boiling mixture as by-product which contains (according to Michaels addition) water, alcohol or methacrylic acid added to methacrylic group. By-product is decomposed in thermal decomposition reactor at simultaneous distillation of decomposition products in distilling column from which methacrylic acid is taken in form of distillate. Flow of liquid decomposition residue is forced for peripheral direction by means of mixing blades before withdrawal from reactor. Peripheral direction is obtained with the aid of liquid fed from the outside of decomposition reactor; to this end use is made of initial high-boiling material or flow of liquid discharged from decomposition reactor. If necessary, etherification stage is performed through interaction with alcohol for obtaining methecrylic ester. Decomposition of by-product formed at obtaining methacrylic acid by oxidation of propylene or isobutylene or at obtaining methacrylic acid by interaction of acid with alcohol by alcohol through introduction of by-product into thermal decomposition reactor provided with distilling column which has plates made in form of disks and toroids for simultaneous decomposition and distillation. Plant proposed for realization of this method includes thermal decomposition reactor and distilling column, level meters and lines for discharge of liquid containing easily polymerized compounds. Level indicator mounted at area of accumulation of liquid shows pressure differential. Line for detecting the side of high pressure of this level meter is connected with accumulated liquid discharge line.

EFFECT: updated technology; increased yield of target products.

38 cl, 14 dwg, 2 tbl, ex

FIELD: chemical technology.

SUBSTANCE: invention relates to technology for synthesis of acetic acid by the cabonylation reaction of methanol with carbon monoxide. Method involves preparing the productive flow in the reaction section containing acetic acid, acetaldehyde, water and other impurities. In the cleansing treatment the reaction products are subjected for treatment wherein acetaldehyde impurities are oxidized to either acetic acid after its isolation and recovered to the reaction zone or to carbon dioxide and water that removed from the system. As result, method provides excluding the negative effect of acetaldehyde at step for separation of the reaction products. Oxygen, air or their mixtures, ozone, carbon peroxide or peracetic acid are used as oxidant. As possible variants of the method, the productive flow is fed to distillation column wherein flow of light products or heavy products are isolated under condition that each of these flow involves acetic acid, acetaldehyde and water. Then "light" or "heavy" flow is subjected for oxidation as said above to reduce the concentration of acetaldehyde. As a variant of the method the flow of heavy products can be treated by extraction with water followed by oxidation of acetaldehyde-containing aqueous phase. Invention provides improvement of method due to exclusion of the necessity of purification of the end product from acetaldehyde impurity.

EFFECT: improved treatment method.

20 cl, 3 tbl, 35 ex

FIELD: industrial organic synthesis.

SUBSTANCE: method comprises contacting vapor-phase mixture at 150-205°C with alkali and/or alkali-earth metal carboxylate dispersed on activated carbon resulting in conversion of alkyl iodides into corresponding carboxylic acid esters, while iodine becomes bound in the form of inorganic iodide.

EFFECT: facilitated freeing of carboxylic acid product from organic iodine compounds.

4 cl, 2 tbl, 32 ex

FIELD: chemical technology.

SUBSTANCE: invention relates to the improved method for extraction of carbonyl and (or) acid compounds from the complex multicomponent organic liquid mixtures. Method involves treatment of organic liquid mixtures with sodium sulfite an aqueous solution at intensity of mechanical stirring providing formation of uniform emulsion. The content of carbonyl compounds and acids in the parent mixture to be treated is determined and treatment is carried out with 4.16-26% aqueous solution of sodium sulfite as measured 1.05-1.1 mole of sodium sulfite per 1 g-equiv. of carbonyl compound, and in exceeding of the content of acids (g-equiv.) in the parent mixture over the content of carbonyl compounds - with 1 mole sodium sulfite per 1 g-equiv. of acids and in the mass ratio of sodium sulfite aqueous solution to organic mixture = (1-2.5):(2-1) at temperature 15-30°C; if the content of acids in the parent mixture (g-equiv.) is less the content of carbonyl compounds (g-equiv.) then under control of pH value change in an aqueous phase method involves additional addition of mineral or organic acid in the amount as a difference in the content of carbonyl compounds (g-equiv.) and the content of acids (g-equiv.) in the parent charge of organic mixture per treatment at such rate that pH value of aqueous would decrease constantly but not less 6.5. This simple method provides removing both carbonyl compounds and acids being without significant limitations for the content of carbonyl compounds and acids in the parent mixture. Invention can be used in different branches of industry for treatment of compositions or for utilization of carbonyl compounds and (or) acids.

EFFECT: improved method for extraction.

5 cl, 3 tbl, 26 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying naphthalene carboxylic acid. Method involves contacting crude naphthalene acid with solvent used for purifying in the presence of hydrogen and catalyst that comprises a precious metal of VIII group taken among palladium, platinum and ruthenium and metal of group IVB taken among silicon, germanium, tin and lead at temperature about from 520 to 575°F. Proposed method provides preparing reduced amount of organic pollution in purified acid as compared with other methods of purification.

EFFECT: improved purifying method.

19 cl, 1 dwg, 5 tbl, 5 ex

FIELD: chemical technology.

SUBSTANCE: invention relates to the improved method for treatment of organic mixtures from carbonyl compounds and acids by their treatment with sodium sulfite. Method involves using organic mixtures comprising carbonyl compounds and carboxylic acids in the ratio = 1 g-equiv. : 1 g-equiv. or with excess of acids, or with excess of carbonyl compounds. In this case before treatment with sodium sulfite carboxylic acid is added to the parent mixture in the amount to obtain the ratio of carbonyl compounds to acids as 1 g-equiv. per 1 g-equiv. and treatment is carried out with solid sodium sulfite in beaded mill with the mass ratio of the composition charge to glass beads as a grinding agent = 1:(1-2) at the rate of mechanical mixer rotation 1440 rev/min, not less, and in dosing sodium sulfite 1.2-1.5 mole per 1 g-equiv. of carbonyl compounds or excess of acid in the presence of stimulating additive up to practically complete consumption of carbonyl compounds, or carbonyl compounds and acids. Process is carried out in the presence of sodium and potassium hydroxide and acetate and sodium nitrate also as a stimulating additive taken in the amount 1-4% of mass sodium sulfite to be added up to practically complete consumption of carbonyl compounds and acids in composition to be treated. This simple method provides high degree of purification being even in small parent content of carbonyl compounds and acids.

EFFECT: improved method for treatment.

4 cl, 3 tbl, 19 ex

The invention relates to an improved method of isolation and purification of adipic acid, used for the production of polyamide-6,6 or polyurethanes, which consists in treating the reaction mixture obtained by direct oxidation of cyclohexane to adipic acid by molecular oxygen in an organic solvent and in the presence of a catalyst, removing by-products from the reaction mixture and the adipic acid by crystallization, and before adipic acid from the reaction environment carry out consistently the following operations: the decantation of the two phases of the reaction medium with the formation of the upper organic the cyclohexane phase, containing mainly cyclohexane, and the lower phase, containing mainly the solvent, the resulting dicarboxylic acid, the catalyst and other reaction products and unreacted cyclohexane; distillation bottom phase to separate, on the one hand, distillate containing at least a part of the most volatile compounds, such as organic solvent, water and unreacted cyclohexane, cyclohexanone, cyclohexanol, complex cyclohexylamine esters and possibly lactones, and, with the pin acid from residue from distillation by means of crystallization and thus obtained crude adipic acid is subjected in aqueous solution purification by hydrogenation and/or oxidation with subsequent crystallization and recrystallization of the purified adipic acid in water

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

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