Method for purifying naphthalene carboxylic acid

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

 

The invention generally relates to the purification of naphthalene compounds, and in particular relates to cleaning naphthalenesulphonic acids.

In industry widely used polymers based on dimethyldithiocarbamate and their respective acids. For example, films made from polymers which contain dimethyl-2,6-naphthalenyloxy (2,6-NDC), have the strength and thermal properties that are superior to the corresponding properties of the films and fibers made from other polymers, such as polyethylene terephthalate (PET). These improved properties has led to the widespread use of polymer based on 2,6-NDC in films for film and cameras, films for magnetic recording, and electrical and electronic components.

The polymer based on 2,6-NDC also have high resistance to diffusion of gases such as carbon dioxide, water vapor and oxygen. This high resistance to diffusion of gases allows the use of such polymers as films and containers for packaging various food products and beverages.

Increased physical strength of the polymer based on 2,6-NDC also allows their use in applications with severe operating conditions, such as a cord for tires of cars and motorcycles.

The use of 2,6-naphthaleneboronic acid in such applications the deposits provides many advantages compared with 2,6 - NDC. First of all, differences of weight between the acid and the ether usually lead to a higher yield of polymer per pound of feedstock. In addition, polymerization of the acid with ethylene glycol creates water, and not more difficult to handle methane, which is produced by polymerization of the ester with ethylene glycol. Moreover, the use of acid on polymeric units that are already designed for processing only monomers of acid type, allows to obtain, in addition to the polymers naphthalenemethylamine components that cannot be performed if there is only essential form.

Production and direct cleaning of acid monomers also can simplify the production of the corresponding monomers. In particular, in the synthesis of 2,6-NDC produce oxidation of 2,6-dimethylnaphthalene (2,6-DMN) to obtain 2,6-naphthaleneboronic acid (2,6-NDA), which then need to be subjected to esterification to obtain 2,6-NDC, using one or more cleaning operations, such as distillation or recrystallization, which is carried out in one or in both of these operations that is necessary to ensure high product yield with high purity. In contrast, direct purification of the oxidation product of 2,6-DMN is relatively simple and therefore reduces the cost of the monomer.

Purification of 2,6-NDA usually is on hold at temperatures near or above 600 degrees Fahrenheit, to allow processing of a relatively high percentage of all dissolved solids. Work at these temperatures requires substantial investment to ensure that the installation can withstand the pressure that occur when working at such high temperatures. Moreover, the work at these temperatures requires a lot of energy for heating the reaction mixtures to the desired temperature to 600 + degrees Fahrenheit. Finally, even under these preferred conditions, the contamination in purified monomer may require further purification before it can be used to prepare the polymer.

Thus, it requires a relatively cheap and effective method of purification of naphthalene two-acid monomer, allowing you to get a lower pollution level than that obtained in the currently used conventional treatment processes at high temperatures.

The author of the present invention found that naphthalene two-acid monomers can be effectively obtained at lower temperatures and with lower levels of solids than those normally used in industry. Surprisingly, when selecting the proper catalyst and operating conditions can be obtained monomer, having the th lower levels of undesirable impurities, to simplify further purification of the acid monomer.

In addition, since the above reaction is carried out at lower temperatures, the author of the present invention have found that the equipment available chemical plants, designed for less severe operating conditions, such as that used for the purification of terephthalic acid, can be used to clean two-acid monomers, such as 2,6-NDA. The use of such existing equipment excludes capital costs associated with construction of rigs capable of operating at a temperature of 600 + degrees Fahrenheit, which is usually used for industrial cleaning NDA, which also contributes to the relatively cheap production of the monomer.

These results can be obtained in the case of using the method of purification of naphthalene carboxylic acid in accordance with the present invention. The method involves introducing into contact not purified naphthalene acid by solvent cleaning in the presence of hydrogen and of a catalyst which contains a noble metal of group VIII selected from palladium, platinum and ruthenium and the metal of the IVB group selected from silicon, germanium, tin and lead, when the cleaning temperature from approximately 520 to 575°F.

Adding metal of group IVB, the advantage is the natural enemy of tin in the amount of weight.% of the total weight of the catalyst, prevadid to reduce the number of DST and 2 NA present in the purified full flow reactor.

The drawing shows a schematic sequence of the method of purification of 2,6-naphthaleneboronic acid.

Further detailed description to clarify the comparison of purification of 2,6-naphthaleneboronic acid manufactured under typical conditions of temperature, cleaning at low temperature the same acid, under conditions which can be created in other chemical process plants, such as installation, which is used for purifying terephthalic acid, From this description experts will become apparent and other embodiments of the invention. For example, you can put that method in accordance with the present invention is suitable for cleaning other similar digisat, such as 1,5-natalijagolosova acid, and other naphthalene acids having one or more acidic functionalities. Thus, the above description is not restrictive.

The author of the present invention have found that the method in accordance with the present invention allows to obtain monomers naphthalene acids, which contain a low residual amount of unwanted naphthalene compounds, which can react under the conditions of polymerization with what reating a branched or end of polymer chains. This advantage can be obtained when working at lower temperatures and lower concentrations of solids than used in industry for cleaning of such acids. In addition, a proper choice of catalyst of a noble metal can significantly improve the quality of the purified acid, obtained by using the specified method.

In particular, the cleaning process should be carried out at temperatures from approximately 520 to 575°F, mostly from 525 to 560°F, and even better, at a temperature of 550°F. Full content of soluble solids in the form of maximum weight percent acid 2,6-NDA, soluble at the reaction temperature should be within the range of from 3.9% at 520°F to 12% at 575°F, 4.4% at 525°F and 10% at 560°F, and about 7% at 550°F.

It should be borne in mind that in the temperature ranges and the content of solids in accordance with the present invention, it should be expected that at higher temperatures the separation yield of 2,6-NDA will be lower, but the relative amount of organic pollutants will be reduced, while at lower temperatures the yield and the relative amount of organic contamination can increase.

Moreover, the author of the present invention have found that the method in accordance with the present invention allows the use shall be other means of purification, such as the purification of terephthalic acid. This is unexpected, since it is usually believed that the purification of naphthalene acids mainly should be carried out at a temperature of 600°F+to increase the amount of dissolved solids present in the raw materials of the reactor cleanup.

The combination of these findings allows the purification of naphthalene acids in different types of equipment that were considered to be unsuitable or undesirable for such work. Thus, the method in accordance with the present invention can reduce capital costs and the cost of energy in new installations, or allows you to use existing equipment such as the reactor for the purification of terephthalic acid, for the production of monomers naphthalene acid of high quality.

Used herein, the term "reactor low temperature" refers to the reactor, designed to work with a nominal operating temperature of less than 600°F and when the appropriate pressure when producing the cleaning of acid monomer in the primary aqueous solvent. "Nominal operating temperature" is considered the temperature at which the reactor can operate continuously, and its maximum operating temperature is usually higher than the nominal operating temperature 1.5-2 p is for.

The drawing shows a block diagram of the experimental setup for the purification of naphthalene acid 10, which is used in comparative example 1 and in example 1 to obtain large quantities of 2,6-naphthaleneboronic acid.

The installation 10 is used for cleaning materials in the form of raw (untreated) acid 2,6-NDA, obtained by oxidation in the liquid phase of 2,6-DMN in the presence of a source of molecular oxygen, whereby the solvent contains monocarboxylic acid and water. The reaction, which is used to obtain the acid of the raw material, usually carried out in the presence of a catalyst which contains compounds of cobalt, manganese and bromine, at a reaction temperature of approximately from 100 to 260°C. the Reaction is mainly carried out in a solvent monocarboxylic acid, such as acetic acid or a mixture of acetic acid and water, with the ratio of solvent to DMN approximately 2:1 to 12:1, with the ratio of manganese to cobalt is approximately from 5:1 to 0.3:1, with the ratio of bromine to the manganese plus cobalt approximately from 0.3:1 to 0.8:1, with the full amount of cobalt plus manganese, up to one weight percent of the selected solvent. Additional information regarding the oxidation of the DMN in the NDA can be obtained from U.S. patent Nos. 5292934 and 5254719.

System 10 does the cleaning of raw materials in the form of the crude acid 2,6-NDA in the following way. Sirev suspension from the tank 12 is heated to the desired operating temperature in the range of steam heaters 14, working in hot oil, after which it enters the hydrogenation reactor 16 with a fixed layer. In reactor 16 are dedicated to the processing of raw materials in the presence of hydrogen and hydrogenation catalyst. Hydrogenated purified stream from the reactor 16 passes through the serpentine carbon filter 18 to remove the fine catalyst particles and other substances. After that, the filtered purified stream crystallizes in the molds 20 and 22.

The upper straps of the molds 20 and 22 are collected and sent to a facility for recycling, while the contents of the molds 20 and 22 are directed to the supply tank rotary drum filter 26 and then filtered in a rotary drum filter 28. Filter sludge rotary drum filter 28, which forms the purified acid 2,6-NDA, dried in a drum dryer 30, is cooled in the cooling apparatus 32 and is sent to the storage hopper 34 for subsequent packaging and shipment.

Comparative example 1

In the hydrogenation reactor 16 downloaded 1,408 pounds of peat coal received at the company Norit Americas, Inc. product Norit ROX 0.8 a, which is extruded to a diameter of 0.8 mm activated carbon, which was washed with acid and has theoretical bulk density of 25.5 pounds per cubic foot.

Suspensiion crude acid 2,6-NDA, which has a composition in accordance with the following table 1A, was prepared in the supply tank 12 at a temperature of about 120°F.

Table 1A

The original composition of the crude acid 2,6-NDA
Solvent cleaningwater
The average weight.% total dissolved solids12%
Wt.% 2,6-NDA as % of all solids96%
Solvent cleaningwater
6-formyl-2-naphthoic acid

("FNA") (ppmw* all solids)
1,120
1-bromo - 2,6 - natalijagolosova acid ("BrNDA") (ppmw as all solids)1,477
solids)
*ppmw - weight parts per million

The raw material was heated in the heater 14 to a temperature of 600°F and introduced into the reaction in hydrogenation reactor 16. The feed rate of the raw material was about 14-15 gallons per minute, with an average concentration of solids in the raw material is about 12 wt.%.

Filtered purified output stream of the reactor was subjected to crystallization in the crystallizer 20 and 22 due to evaporative cooling flow. The output stream Krista is of the catalysts was twice washed with water and filtered at a temperature of approximately 300 to 400° F, was obtained crystallized acid in suspension in the water, which was filtered on a rotary drum filter 28 when the ambient pressure and dried at a temperature of approximately 250°F for 60 minutes in a drum dryer 30. Dry purified acid 2,6-NDA has a composition, averaged over 7 batches of approximately 20,000 pounds, is given in table 1B.

Table 1B

The acid composition of the purified 2,6-NDA
Wt.% 2,6-NDA (as wt.% total dissolved solids)99,8
6 - four mil - 2 - naphthoic acid (as ppmw* all solids)23
1-bromo-2,6 - natalijagolosovanot found
acid ("BrNDA") (ppmw as all solids)(<20 ppmw)
2 - naphthoic acid ("2 - NA") (as

ppmw of all solids)
106
6-methyl-2-naphthoic acid

("6-Me-2-NA") (ppmw as all solids)
130
2,6-dicarboxylicacid ("2,6-

DCT") (ppmw as all solids)
488
Trimellitate the acid (TMLA) as ppmw of all solids)not detected (<10 ppmw)
* ppmw - parts by weight of nmillion

The figures in table 1B data shows that the purified acid has lots of naphthalene contamination.

In the following example 1 illustrates the advantages of working at lower temperatures using a catalyst made of noble metals.

Example 1

In the hydrogenation reactor 16 downloaded 1,369 pounds of catalyst, which has a 0.5 wt.% palladium (based on the total weight of the catalyst) on 4×8 mesh granular carbon media purchased by the company Engelhard Corporation. As before in comparative example 1, the suspension of the original crude acid 2,6-NDA, which has a composition in accordance with table 1A, was prepared in the supply tank 12 at a temperature of about 120°F.

The raw material was heated in the heater 14 to a temperature in the range from 525 to 565°F and introduced into the reaction in hydrogenation reactor 16. The feed rate of raw materials accounted for approximately 13 to 16 gallons per minute, with an average concentration of solids in raw materials from approximately 4 to 6.5 wt.%.

Filtered purified output stream of the reactor was subjected to crystallization in the crystallizer 20 and 22 due to evaporative cooling flow. The output stream of the mold was washed twice with water and filtered at a temperature of from approximately 310 to 345°F, was obtained Krista is realized acid in suspension in water, which was filtered on a rotary drum filter 28 under ambient pressure and dried at a temperature of approximately 250°F for 60 minutes in a drum dryer 30. Dry purified acid 2,6-NDA has a composition, averaged over 4 batches of approximately 20,000 pounds, are shown in table 2.

Table 2

The composition of the purified 2,6-NDA
Wt.% 2,6-NDA (as wt.% total dissolved solids)99,9
6-formyl-2-naphthoic acid ("FNA") (ppmw* all solids)not detected (<8 ppmw)
1-bromo-2,6-natalijagolosovanot found
acid ("BrNDA") (ppmw as all solids)(<20 ppmw)
2-naphthoic acid ("2-NA") (ppmw as all solids)124
6-methyl-2-naphthoic acid ("6 - Me - 2 - NA") (ppmw as all solids)10
2,6-dicarboxylicacid ("2,6 - DCT") (ppmw as all solids)not detected (<10ppmw)
Trimellitate the acid (TMLA) as ppmw of all solids)not detected (<10 ppmw)
*ppmw - weight parts per million

A comparison of the data in table 1B data table is s 2, you see, in the purified acid were found FNA, BrNDA, TMLA or 2,6-DCT. All these impurities are harmful for the polymerization of 2,6-NDA monomer, when present in significant quantities. Therefore, the absence of these impurities in the acid, purified using the purification method at low temperature with Pd/C catalyst in accordance with the present invention shows the advantage of this method.

As a metal catalyst for the method in accordance with the present invention can be used noble metals of group VIII, and predominantly palladium, platinum and ruthenium. As shown in the following example 2, the cleaning method provides unexpectedly better results when the metal catalyst is palladium.

The noble metal may be any inert carrier, which remains stable under the given process conditions, such as the carrier of coal (carbon) or rutile phase of titanium dioxide. The preferred carriers are the carriers of activated carbon, such as coal from a nutshell, although it may be used and granulated charcoal. Noble metal must be present in an amount of approximately from 0.1 to 3.0 percent of the total weight of the catalyst, predominantly from approximately 0.35 to 0.8 percent of the total weight of the catalyst, and the best is, about 0.5% of the total weight of the catalyst. The preferred catalyst contains about 0.5 wt.% palladium on the carrier of coal from a nutshell.

An unexpected advantage of the catalyst of palladium on a carbon carrier in the method in accordance with the present invention shown in example 2.

Example 2

Laboratory comparison of the purification of 2,6-NDA with the use of palladium on a carbon carrier, ruthenium on carbon carrier and platinum on carbon carrier was held in conditions that simulate the purification of 2,6-NDA in the installation for the purification of terephthalic acid, in which the reactor was designed to operate at a nominal operating temperature of no higher than about 550°F. Were compared to find the relative efficiency of noble metals in reducing staining and quantities DCT and 2-NA, obtained using the method in accordance with the present invention.

Continuous hydrogenation was performed in a reactor with a fixed bed. Typical conditions of the reactor corresponded to a temperature of 550°F and the content of 6.25 wt.% all solids. The volume of the reactor is 75 cm3and the feed rate ranges from 7 to 12 grams per minute, at a flow rate of hydrogen from 3 to 10 milliliters per minute.

Used all obtained at the output of the reactor solids for analysis of organic content is of exist using liquid chromatography, moreover, the entire output of the reactor were filtered at 140°F and dried, and produced an analysis of the color obtained on the filter sediment.

The results of the comparison are summarized in the following table 3.

Table 3
CatalystL*b*2-NA (wt.% from the flow reactor)DCT (wt.% all flow reactor)
0.5 wt.% Pd/C96,48,160,23a 4.9
1.0 wt.% Ru/C94,5the 6.066,23,5
0.5 wt.% Pt/C94,47,835,87,2

As can be seen from table 3, palladium on carbon carrier can obtain purified acid which contains 2 times less pollution in comparison with the case of using a catalyst of ruthenium and 3 times less pollution in comparison with the case of using a catalyst made of platinum. Moreover, palladium, and ruthenium in 2 times more efficient than platinum in reducing the number of DCT present in a purified stream of the reactor. Thus, the only noble metal, which can significantly reduce the content of 2-NA, and DCT is palladium. At the same time does the e significant phenomena staining was not observed.

Additional benefits can be obtained through modification of the catalyst metal of group VIII in accordance with the present invention by using supplements is approximately from 0.1 to 2.5 wt.%, but mainly approximately from 0.2 to 0.6 wt.% metal of group IVB, such as silicon, germanium, tin or lead, as shown in the following example 4.

Example 4

The catalyst of ruthenium on carbon media of example 3 was upgraded due to additives 0.4 wt.% tin (calculated on the total weight of the catalyst). Was repeated the experiment of example 3 under the same conditions. As you can see from the table below 4, the introduction of tin halving the amount of DCT present in purified full flow reactor, and also reduces approximately by 25% the number of 2-NA, present in the purified full flow reactor

Table 4
Catalyst2-NA (wt.% from the flow reactor)DCT (wt.% all flow reactor)
1.0 wt.% Ru/C6,23,5
1.0 wt.% Ru/C + 0.4 wt.% Snthe 4.70,71

An unexpected decrease in the content DCT, obtained by modification of the catalyst of ruthenium on a carbon carrier in the low-re is store in accordance with the present invention, shows that the modified metal of group IVB catalysts of noble metal allow you to get purified acid monomers having a substantially reduced content of DCT.

1. The method of purification of naphthalene carboxylic acid, which provides for introduction to the contact of the crude naphthalene acid by solvent cleaning in the presence of hydrogen and of a catalyst which contains a noble metal of group VIII selected from palladium, platinum and ruthenium and the metal of the IVB group selected from silicon, germanium, tin and lead at the cleaning temperature from approximately 520 to 575°F.

2. The method according to claim 1, wherein the naphthalene carboxylic acid is a 2,6-naphthaleneboronic acid.

3. The method according to claim 1, characterized in that the noble metal is palladium.

4. The method according to claim 1, characterized in that the noble metal is applied on the carbon carrier.

5. The method according to claim 1, characterized in that the acid is 2,6 - natalijagolosova acid, prepared at the expense catalyzed using heavy metal liquid phase oxidation of 2,6 - dimethylnaphthalene.

6. The method according to claim 1, characterized in that the noble metal catalyst is palladium on a carbon carrier, and naphthalene carboxylic acid is a 2,6 - naphthalenemethanol KIS the GTC.

7. The method according to claim 6, characterized in that 2,6 - naphthaleneboronic acid cleaning is cooked through catalyzed using heavy metal liquid phase oxidation of 2,6-dimethylnaphthalene.

8. The method according to claim 1, characterized in that the cleaning temperature is approximately from 525 to 560°F.

9. The method according to claim 1, characterized in that the total content of dissolved solids in solvent cleaning is less than 12 wt.% in terms of the total weight of solids plus the solvent.

10. The method according to claim 7, characterized in that the total content of dissolved solids in solvent cleaning is less than 10 wt.% in terms of the total weight of solids plus the solvent, the cleaning temperature is approximately from 525 to 560°F.

11. The method according to claim 1, characterized in that it is carried out in the reactor cleaning, designed for operation at a nominal working temperature of not more than approximately 550°F.

12. The method according to claim 6, characterized in that it is carried out in the reactor cleaning, designed for operation at a nominal working temperature of not more than approximately 550°F.

13. The method according to claim 10, characterized in that it is carried out in the reactor cleaning, designed for operation at a nominal working temperature of not more than approximately 550°F.

14. The method according to claim 1, great for the present, however, that the purified acid is extracted by separating solids from the liquid at a temperature of approximately from 300 to 340°F.

15. The method according to claim 6, characterized in that the purified acid is extracted by separating solids from the liquid at a temperature of approximately from 300 to 340°F.

16. The method according to claim 10, characterized in that the purified acid is extracted by separating solids from the liquid at a temperature of approximately from 300 to 340°F.

17. The method according to claim 1, characterized in that the metal of the IVB group is tin.

18. The method according to claim 1, characterized in that the metal of the IVB group is present in an amount of from 0.2 to 0.6 wt.% of the total weight of the catalyst.

19. The method according to 17, characterized in that the noble metal is ruthenium, which is present in quantities of from 0.1 to 3.0 wt.% of the total weight of the catalyst.



 

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20 cl, 3 tbl, 35 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: 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: chemistry.

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

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

19 cl, 1 dwg, 6 ex, 4 tbl

FIELD: chemistry.

SUBSTANCE: 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: 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: 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

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