The method of obtaining isomers benzylcarbamoyl acids with a high degree of purification

 

(57) Abstract:

Use: in the manufacture of films and fibers. The inventive product-isomer benzylcarbamoyl acids. Index color: 7 deg. H-6 deg.N. Contents 4 KBA 14 million Reagent 1: n-xylene. Reagent 2: air. Process conditions: in the presence of Co-Mn catalyst containing Ni, Cr, Zr, Ce or mixtures thereof, and a halide compound, after the first stage of oxidation, consisting of two stages, the precipitate was separated from the solvent and then the process is returned to the cycle solvent, then the resulting slurry is heated to a high temperature for extraction of impurities contained in the solid product is cooled and treated with air and catalysts in the second stage of oxidation. The precipitate obtained in the second stage of oxidation, is separated again from the solvent and process again recycle solvent, and then heated to a high temperature for extraction, cooled and treated with air and catalysts in the third stage of oxidation. 6 C. p. F.-ly, 2 tab. 1 Il.

The invention relates to a method for isomers benzylcarbamoyl acid with a high degree of purity, and this method does not require the stage of purification by the method of hydrogenation.

Those who by the SD method, which is the oxidation of p-xylene with molecular oxygen in the presence of catalysts, including heavy metals in the environment solvent acetic acid. However, terephthalic acid obtained by this method contains a large number (1000-3000 hours per million) of 4-carboxyanhydride (4-KBA), which is not suitable for the production of polyester films and fibers. So usually interact terephthalic acid (TC) with methanol to form terephthalate, which is easily cleaned and reacts with the glycol to form a polyester. Another way to clean teleftaios acid is dissolving terephthalic acid in water at high temperature and pressure, and processing the resulting solution with hydrogen over catalysts based on noble metals, including palladium, obtaining terephthalic acid with high purity, containing less than 25 hours per million 4-KBA. However, both of these methods have disadvantages. When performing the first cleaning method, using terephthalate, upon receipt of the polyester is formed methanol. With the implementation of the second method in the stages of oxidation and purification using different solvents, catalysts and settings westline these methods, it was proposed a few methods.

A method of obtaining TC oxidation of p-xylene with molecular oxygen in the presence of a heavy metal and bromine compounds, dissolved in acetic acid with receiving TC with the degree of conversion of more than 90% of Technical TC obtained by this reaction, crushed in the acetic acid medium at 140-230aboutIn the presence of molecular oxygen to reduce the average particle diameter is more than 20% of the Sludge obtained in this first stage of cleaning oxidized in a second stage at a temperature of at least 10aboutWith higher than the temperature in the first stage, or at a temperature in the range of 180-300aboutIn order to obtain purified TC, suitable for receiving the polymer [3] For the implementation of this process requires special equipment for crushing of terephthalic acid, which causes technical difficulties with the provision of high speed stirrers, if the latter is used for grinding. In addition, this method is difficult to obtain a TC with a high degree of purity, containing less than 0.0025% 4-KBA.

Also known cleaning method TC, consisting in processing oxygen-containing gas technical product Parow, consisting of compounds of cobalt, manganese, chromium, cerium, lead or mixtures thereof in an amount of 0.01 to 5.0% of the weight of the LC subjected to clearing [2] the Process is carried out for 1 h at 250aboutC. the Disadvantage of this method is the continuous contacting of the reactants at high temperature, which causes oxidation as impurities, and acetic acid.

The closest in technical essence and the achieved result to a method for TC with a high degree of purity is the method of stepwise oxidation of p-xylene oxygen-containing gas in an acetic acid medium in the presence of catalysts containing cobalt-manganese-bromine [1] the Process is carried out in four stages. In the first stage p-xylene oxidize at 180-230aboutWith over 40 to 150 min, the degree of conversion of p-xylene is more than 95% In the second stage, the temperature of 20-90aboutC lower than the temperature of the first stage and the reaction time is 20-90 min, the third reaction stage is carried out at 235-290aboutC for 10-60 min, the fourth phase at 260aboutC. TC obtained by this method contains 0,027% 4-KBA, and therefore is of limited use for the production of polyester fibers and films.

The main disadvantages of this sposobina and fourth stage), causes not only oxidation of these impurities, but also acetic acid, which degrades the technical and economic indicators of the process;

b) pretty much the duration of the first stage of oxidation of p-xylene (90 min) reduces the efficiency of the process;

C) a high content of 4-KBA (0,027%) in TC limits the possibility of its use in the production of high-quality polymers.

The invention relates to the technology of isomers benzylcarbamoyl acids (BDK) without purification stages technical isomers BDK by catalytic hydrogenation of the impurities and the implementation of the selective liquid-phase oxidation with a minimum loss of solvent.

It was found that this problem can be solved by the method of three-stage liquid-phase oxidation of xylene isomers oxygen-containing gas in the environment of the lower aliphatic acid at 150-230aboutC and elevated pressures in the presence of catalysts consisting of salts of cobalt and manganese and halide compounds, modified by the addition of heavy metals (IU), for example, Nickel, chromium, zirconium, cerium, taken separately or in mixture with each other. After each stage the product is separated from rastvoritelei. After replacement of the solvent sludge BDK subjected to the extraction step to remove impurities contained in the solid, in solution, so that these impurities be subjected to selective oxidation to the next stage of oxidation.

The ratio of the concentrations of the modifying additives metals (IU) with respect to Co and Mn should be in the range of (Co+Mn):Me=1:0,01-0,2.

The relative concentrations of the catalysts in each stage are first:second:third=1:0,1-0,5:0,01-0,1.

As halide compounds used connection bromine, or a mixture of compounds of bromine and chlorine in the ratio Br:Cl=1:0,001-0,5. Nutrient mixture containing the isomers of xylene, solvent and catalyst is heated to a temperature higher than the temperature of dissolution of the catalyst and solid recycled oxidation products, but below the temperature oxidation and served in the reaction zone of the first reactor of the first stage counter-current to the direction of rotation of the liquid flow in the reactor with a linear speed 6-30 m/c in the form of restricted submerged jets.

The reaction mixture is treated with molecular oxygen or oxygen-containing gas at 150-230aboutWith up to a residual content of isomer KBA 0.1-0.4% in prod is E. it is treated with a mixture of molecular oxygen or oxygen-containing gas, leaving the first reactor, and dehydrated (N2About 5% ) acetic acid solution in the form of distillate from the mold at the first stage and/or recycle the mother liquor after separation benzylcarbamoyl acid in the second stage to obtain the residual concentration of the isomer KBA, 0.05-0.15% of the Reaction mixture is then injected into the mold and the separator, and the pressed product is processed by solvent recovered from the third stage of oxidation in such quantity that at least 60% of the initial solvent were driven recovered solvent. This suspension is heated to 200-250aboutC and maintained at this temperature 5-60 min for extraction of impurities. Then the suspension is cooled and treated with molecular oxygen or oxygen-containing gas in the second stage oxidation to obtain a residual concentration of isomer KBA in the reaction product is equal to 0,02-0,03%

The reaction mixture is then passed into the mold and the separator, the resulting product is treated with recycle solvent coming from the tank washing, up until at least 60% of the initial solvent will not VitaScene recycling. The resulting slurry is heated to 200-250about

The advantage of the invention consists in the selective oxidation of xylene isomers with getting isomers benzylcarbamoyl acids in high yields at moderate temperatures, thus almost completely eliminated adverse reactions that cause the formation of the colored high molecular weight product. With this purpose, in the process at each stage using a suitable catalytic composition and concentration. The use of low concentrations of heavy metals and additives metals, as well as the application of a mixture of halide compounds provides the ability to control the flow of fast and slow reactions. The method of feeding the reactants into the reactor to provide nearly continuous distribution in the reaction zone substantially reduces the loss of the lower aliphatic acid used as a solvent due to oxidative decomposition. The application of the displacement of the solvent and extraction of the impurities in the interval between stages of oxidation increases the efficiency of the selective oxidation of impurities. In the method according to the invention leads to the production of high-purity isomers benzylcarbamoyl acid is the solvent (35-40 kg/t BDK).

The drawing shows a diagram of the method according to this invention.

The invention is illustrated by the following examples.

P R I m e R 1. Oxidation of p-xylene is carried out in a continuous action, consisting of a collection for nutrient reaction mixture (ORS), pump, oxidation reactor, equipped with stirrer, condenser and mold. The collection ORS load the reaction mixture of the following composition, g: acetic acid 2020 p-xylene 330 acetate tetrahydrate With 2.4 acetate tetrahydrate (Mn 1.2 zirconiabased 0,24 Hydrobromic acid (40%) 3,61

Prior to reactor startup ORS heated at 160aboutC. After reaching this temperature include the pump and the reactor serves ORS. Almost simultaneously serves the air. At this point, the temperature is 192aboutC. the composition of the gases (O2, CO, CO2), temperature, pressure, feed rate ORS and air is constantly being written to. At regular intervals, take samples of the liquid reaction products containing a solid phase. The sample is separated into liquid and solid phases, qualitative and quantitative analysis is performed by chromatographic, polarographic and spectrometry.

After oxidation of the sludge at 185aboutWith a mixture of air and gas leaving the first reactor of the first stage of oxidation, and the distillate from the condenser of the mold located at the first stage.

TC obtained on the filter is the first stage, is treated with a liquor returned in the cycle after the third stage of oxidation, and served in the reactor of the second stage of oxidation. The contents of the reactor are heated to 230aboutC and then aged 7 minutes, the Temperature is gradually reduced until at least 198aboutC. the Concentration of catalyst in the reaction mass is 5 times less than the concentration of catalyst in the reaction mass in the first reactor of the first stage of oxidation. Carry out the second stage of oxidation. The results show that the content of 4-KBA in TC decreases from 950 hours per million (0,095%) up to 210 h per million (0,021%), and the index of the color decreases from 9 to 7aboutN. Sediment TC obtained in the second stage of the oxidation process recycling of acetic acid used for washing after the third stage of the reaction, and the resulting slurry, as in the second phase, heated to 230aboutWith, stand 7 min and cooled at least to 198aboutC. Then carry out the third stage of oxidation. The amount of catalyst added to the reactor in the third stage, in Aleut TC and washed with fresh acetic acid. Conditions of the oxidation process and the results are shown in table.1. Contents 4-KBA in TC decreases from 210 million to 14 hours per million (0,0014%), and the index color from 7 to 6aboutN.

P R I m m e R 2. The process is carried out as in example 1. The only difference is that zirconiabased replace circinelloides in equimolar amounts in the calculation of the zirconium. The results obtained are due to the replacement of zirconiabased circinelloides in respect of the index color does not change, however, the content of 4-KBA in TC decreases from 14 h per million (0,0014%) up to 11 h per million (0,0011%).

P R I m e R 3. The process is carried out as in example 1. The only difference is that in the catalyst instead of zirconiabased take the uranyl chloride Nickel. Contents 4-KBA in TC, similar to the data in example 2, but the index color improves.

P R I m e R 4. The process is carried out under the conditions of example 1. The only difference is the replacement of zirconium compounds in the compound of cerium. The results obtained indicate receipt of TC with a high degree of purity.

P R I m e R 5. The process is carried out as in example 1, the only difference is the replacement of the connection>/P>P R I m e R 6. The process is carried out as in example 1, but as modifying additives are used at the same time, acetates, Zr, Ni and Cr. The quality of the TC is improved as the content of 4-KBA, and the index color.

P R I m e R 7 (comparative). The process is carried out in the conditions of example 6, but exclude modifying additives, and in the composition of the catalyst remain only Co, Mn and Br. The obtained TC on the content of 4-KBA does not meet the requirements for high-purity products, and the index of the color worse than the TC obtained in examples using modifiers salts of Zr, Ce, Cr, Ni.

P R I m e R s 8, 9. The process is carried out in the installation of oxidation of p-xylene continuous action, including two consecutive reactor, under the conditions of example 1. The first and second reactors are equipped with bunk turbine agitators. In the reactor there are four nozzles to enter the reaction mixture with a speed of 18 m/s Streams emerging from the nozzles is directed countercurrent to the direction of rotation of the reaction mass near the periphery of the blades of the agitator. TC obtained in the first stage is finally oxidized at the second and third stages. The results are shown in table.1 and 2. Receive high-purity TC.

P R I m e R s 11, 12 (comparative). The process is carried out using o - and m-xylene under the conditions of example 1. The only difference is the replacement of the zirconium compounds to the compound of Nickel. Get isophthalic and phthalic acid with a high degree of purity.

1. The method of obtaining isomers benzylcarbamoyl acids with a high degree of purity by sequential liquid-phase oxidation of xylene isomers with molecular oxygen or oxygen-containing gas in the environment of the lower aliphatic acid with stirring and at a speed of certain temperature intervals at each stage, in the presence of catalysts consisting of salts of cobalt and manganese and halide compounds, characterized in that the oxidation is carried out in three stages so that the first stage of a nutrient mixture containing the isomers of xylene, lower aliphatic acid and the catalyst is subjected to oxidation in two sequential reactors, moreover, nutrient mixture heated to a temperature below the temperature oxidation fed to the first reactor of the first stage oxidation protiven in the second reactor to carry out the crystallization and separation of the precipitate obtained benzylcarbamoyl acid, which then processes the return to the cycle of the lower aliphatic acid recovered from the third stage of oxidation, while the impurities contained in the solid product, extracted at a temperature of 200 250oC for 5 to 60 min in a solution coming in the second stage of oxidation, then the product of the second stage of oxidation is subjected to crystallization and separation of the pressed sludge with subsequent processing and final oxidation at the third stage, and used in the process, the catalyst further comprises a modifier additive compounds of heavy metals, including Nickel, chromium, zirconium or cerium, taken separately or in mixture with each other, while the concentration ratio of (Co + Mn) modifying additive is 1 to 0.01 to 0.2, and the relative concentration of the modified catalyst is equal to 1 0,01 0,1 0,5 0,1 at first, the second and third stages, respectively.

2. The method according to p. 1, characterized in that the first stage of the oxidation is carried out at 150 to 230oWith, and the second and third stage of oxidation at a temperature of at least 2 80oWith lower temperature extraction.

3. The method according to p. 1, characterized in that the reaction mass in the second reactor of the first stage is treated with the acetic acid solution in the form of distillate from the first stage crystallizer and/or recycle the mother liquor after separation benzylcarbamoyl acid in the second stage.

4. The method according to p. 1, characterized in that the processing of pressed sludge obtained in the second stage of oxidation, conduct return to the cycle of the lower aliphatic acid from the installation of the washing of the third stage of oxidation.

5. The method according to p. 1, characterized in that as a halide compounds are used bromine compounds or mixture of compounds of bromine and chlorine in the ratio of bromine: chlorine 1 0,001 0,5.

6. The method according to p. 1, characterized in that the recovered sludge treatment solution after the first stage of oxidation is accompanied by the displacement of at least 60% of the original solvent.

7. The method according to p. 1, characterized in that the processing of the sludge is returned into the cycle of the lower aliphatic acid after the second stage of oxidation is accompanied by the displacement of at least 60% of the original solvent.

 

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EFFECT: production of stable quality acid, rational consumption of resources, power and water for performing process.

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: process engineering.

SUBSTANCE: invention relates to removal of impurities and mother solution and wash filtrate extraction from oxidising reactor discharge flow formed in synthesis of carboxylic acid, usually, terephthalic acid. Proposed method comprises: (a) directing oxidised flow in zone of enrichment by solid particles to settle solid particles and form dumping flow suspension via cooling it, adding settling agent, removing solvent or combining said cooling and adding; (b) separating dumping flow suspension in separation zone to form filter pad and mother solution and forced flushing of said filter pad at high pressure in said separation zone by flushing fluid flow comprising water and, not obligatorily, solvent to form washed pad. Note here that said separation zone comprises at least one filter device operated at pressure and comprising at least one filter cell. Note also that said filter cell accumulates layer of filter pad with depth of at least 0.635 cm (0.25 inch), "c" directing at least a portion of flushing filtrate and at least a portion of mother solution to oxidising zone.

EFFECT: higher efficiency.

44 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing aromatic carboxylic acids. The method involves the following, for example: bringing material which contains at least one substituted aromatic hydrocarbon, in which the substitutes can be oxidised to carboxyl groups, with oxygen gas in a liquid-phase oxidation reaction mixture which contains monocarboxylic acid as a solvent and water, in the presence of a catalyst composition meant for oxidising the substituted aromatic hydrocarbon to an aromatic carboxylic acid, containing at least one heavy metal, in a reaction section at high temperature and pressure sufficient for preservation of the liquid-phase oxidation reaction mixture and formation of an aromatic carboxylic acid and impurities containing by-products of the reaction, dissolved or suspended in the liquid-phase oxidation reaction mixture and a high-pressure vapour phase which contains a solvent - monocarboxylic acid, water and small quantities of the initial aromatic hydrocarbon and by-products of oxidation of the initial aromatic hydrocarbon and the solvent - monocarboxylic acid; moving the high-pressure vapour phase from the reaction section to a separation section in which the solvent - monocarboxylic acid, water and oxidation by-products are separated into at least one first liquid phase rich in the solvent - monocarboxylic acid and at least one second liquid phase rich in water, and at least one second high-pressure vapour phase stripped of the solvent - monocarboxylic acid, which contains water vapour, so that by-products of oxidation of the initial aromatic hydrocarbon are preferably in the first liquid phase and by-products of oxidation of the solvent - monocarboxylic acid are preferably in the second high-pressure vapour phase; and removal from the separation section in separate streams of the first liquid phase which is rich in the solvent - monocarboxylic acid, and the second liquid phase rich in water, which contains less than 5 wt % solvent - monocarboxylic acid and by-products of its oxidation, and the second high-pressure vapour phase which virtually contains less than 2 wt % by-products of oxidation of the initial aromatic hydrocarbon.

EFFECT: invention relates to an apparatus for producing aromatic carboxylic acids.

45 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of recovering energy during production of aromatic carboxylic acids via liquid phase oxidation of aromatic hydrocarbons wherein vapour containing reaction solvent and water forms in the top part of the reactor, and the method comprises the following steps: a) high efficiency separation of the vapour from the top part of the reactor to form at least a high-pressure gas stream containing water and organic impurities; b) recovering heat of the high-pressure gas stream via heat exchange with a heat sink, where a condensate forms, said condensate containing approximately 20-60 wt % water, present in the high-pressure gas stream, and high-pressure exhaust gas containing approximately 40-80 wt % water present in the high-pressure gas stream, remains uncondensed and temperature or pressure of the heat sink increases; and c) expansion of the high-pressure exhaust gas which is uncondensed at step (b), containing approximately 40-80 wt % water, present in the high-pressure gas stream, in order to recover energy of the high-pressure exhaust gas in form of work; and d) directing the heat sink, whose temperature and pressure increases at step (c), to another step of the method for heating or using outside the method. The invention also relates to a method of producing aromatic carboxylic acids with energy recovery and a device for recovering energy.

EFFECT: invention significantly lowers power consumption during production of aromatic carboxylic acids.

16 cl, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to improved methods of producing aromatic carboxylic acids, involving bringing material containing at least one initial substituted aromatic hydrocarbon, where the substitutes are oxidisable to carboxylic acid groups, with oxygen gas in a liquid-phase oxidation reaction mixture containing a monocarboxylic acid as a solvent and water, in the presence of a catalyst composition containing at least one heavy metal, which is effective for catalysing oxidation of the substituted aromatic hydrocarbon to an aromatic carboxylic acid, in a reaction section at high temperature and pressure, effective for keeping the liquid-phase oxidation reaction mixture in a liquid state and forming an aromatic carboxylic acid, and impurities containing by-products of oxidation of the initial aromatic hydrocarbon, which are dissolved or suspended in the liquid-phase oxidation reaction mixture, and a high-pressure vapour phase containing a solvent - monocarboxylic acid, water and small amounts of the initial aromatic hydrocarbon and by-products; transferring the high-pressure vapour phase from the reaction section into a separation section sprinkled by a liquid reflux containing water and capable of almost completely separating the solvent - monocarboxylic acid and water in the high-pressure vapour phase to form a liquid rich in solvent - monocarboxylic acid and depleted of water, high-pressure gas containing water vapour; transferring the high-pressure gas containing water vapour from the separation section without processing to remove organic impurities into a condensation section and condensation of the high-pressure gas to form a liquid condensate containing water and exhaust gas from the condensation section under pressure, containing non-condensed high-pressure gas components, transferred into the condensation section; removal from the condensation section of a liquid condensate containing water and suitable for use without further processing as at least one liquid containing water in a method of purifying aromatic carboxylic acids; and feeding the liquid condensate containing water removed from the condensation section during purification of aromatic carboxylic acids in which at least one step includes: (a) preparing a purification reaction solution containing an aromatic carboxylic acid and impurities which are dissolved or suspended in a liquid containing water; (b) bringing the purification reaction solution containing aromatic carboxylic acid and impurities in the liquid containing water, at high temperature and pressure, into contact with hydrogen in the presence of a hydrogenation catalyst to form a liquid purification reaction mixture; (c) separating the solid purified product containing carboxylic acid from the liquid purification reaction mixture containing aromatic carboxylic acid and impurities in the liquid containing water; and (d) using at least one liquid containing water to wash the obtained purified solid aromatic carboxylic acid separated from the liquid purification reaction mixture containing aromatic carboxylic acid, impurities and the liquid containing water; such that the liquid containing water on at least one step of the purification method contains a liquid condensate containing water and which needs processing to remove organic impurities.

EFFECT: invention also relates to apparatus for producing aromatic carboxylic acids.

44 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of processing polyethylene terephthalate wastes. The method involves ethanolysis of polyethylene terephthalate (PET), in which material containing PET reacts with ethanol. Ethylene glycol and an aromatic diethyl ester, such as diethyl isophthalate and/or diethyl terephthalate, are separated. PET or a terpolymer containing a terephthalate monomer and ethylene glycol monomers react with ethanol and ethanol, diethyl terephthalate, ethylene glycol and optionally diethyl isophthalate are separated. The separated diethyl components can undergo liquid-phase oxidation to obtain an aromatic carboxylic acid. Acetic acid can also be obtained via liquid-phase oxidation of the separated diethyl components. Aromatic carboxylic acid can be used to obtain polymers. The invention also describes apparatus for processing polyethylene terephthalate wastes. The apparatus includes a reactor, a distillation column operating at atmospheric pressure and a vacuum distillation column.

EFFECT: high efficiency of the method.

29 cl, 1 dwg, 8 tbl, 8 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing aromatic carboxylic acid. Said method involves an oxidative step for oxidising an alkyl aromatic compound in the presence of a bromine compound to obtain an aromatic carboxylic acid; and a step for burning exhaust gas formed at the oxidation step in an incinerator. The gas obtained after burning the exhaust gas at burning temperature ranging from 450°C to 1000°C is cooled to 250°C or lower, and the time for cooling from 450°C to 250°C in the cooling process is not more than 1 second.

EFFECT: use of the present method enables to inhibit formation of bromine-containing dioxins.

11 cl, 1 tbl, 4 ex, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of obtaining aromatic dicarboxylic acid, with the claimed method including the following stages: (a) oxidation of an aromatic compound in at least one oxidation device with thus obtaining oxidation device discharge gases and the oxidation device suspension, which includes aromatic dicarboxylic acid, with the said oxidation device discharge gases containing at least 12.4 kilograms of steam per a kilogram of the said aromatic compound, supplied into the oxidation device; (b) extraction of hydrocarbon compounds from the said oxidation device discharge gases in the system of a solvent regeneration with thus obtaining poor in hydrocarbons discharge gases, containing at least 3 kilograms of water steam per a kilogram of the said aromatic compound, supplied into the oxidation device; and (c) passing at least a part of the said poor in hydrocarbons discharge gases through at least one turbo-expander to generate work in this way, and the said poor in hydrocarbons discharge gases, supplied into the said turbo-expander, include at least 3 kilograms of water steam per a kilogram of the said aromatic compound, supplied into the said oxidation device. Application of the discharge gases results in an increased shaft power, greater than the required one for driving the main air compressor, even with preferable, relatively low temperatures of oxidation. At the same time, an amount of sewage waters, greater than water obtained as a by-product of xylol oxidation, is held in a steam form and processed together with environment pollutants in the discharge gases in a device for the self-supported (self-feeding) gas phase thermo-oxidative degradation.

EFFECT: invention provides an improved energy content and extraction of shaft power from the discharge gases in reactions of xylol oxidation, simultaneously reducing to the minimum expenditures for sewage water processing.

29 cl, 1 dwg

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