Method of production of high-purity isophthalic acid

 

(57) Abstract:

Getting isophthalic acid are the combination of two interrelated processes of liquid-phase catalytic oxidation of m-xylene O2gas in the medium of acetic acid and recrystallization technical IFC. The oxidation process leading to the cascade of two consecutive reactors in the temperature interval 180-198oC in the presence of a catalyst consisting of salts of acetates Mn and Co and a mixture of compounds of bromine (HBr). In the catalyst composition additionally introduce chlorine in the form of LiCl or its mixture with MnCl2, CoCl2, HCl. The atomic ratio of chlorine:bromine = 1: (1-1,9). The duration of mixing of the reactants in the oxidation zone 12, the residual concentration of m-carboxybenzene in the oxidation products of 0.15-0.25 wt.% Cleaning IFC from intermediate and by-products is at the stage of recrystallization in acetic acid and/or water at 185-220°C and subsequent cooling in four stages. This recycling of mother solutions after extraction of crude (Filtrate 1) and high purity (Filtrate 2)IFC, as well as the removal of the reaction water from the oxidation reactors and crystallizers for optimum composition of the solvent (uksusnoi, table 1.

The invention relates to organic and petrochemical synthesis, in particular to a method for producing high-purity isophthalic acid (IFC) is one of the most widely used monomers for the manufacture of polymeric materials: high-quality polyester fibers, films and coatings for food and technical purposes, isoparaffinic resins, fibrous plastics, synthetic leather, polymer concretes, etc.

Most modern industrial syntheses of IFC-based two-stage processes. The first stage includes the process of liquid-phase catalytic oxidation of m-xylene with molecular oxygen in an acetic acid medium with obtaining technical isophthalic acid. In the second stage do the cleaning technical IFC by catalytic hydrogenation of impurities in the aqueous solution or method of recrystallization in different solvents.

For example, according to patent technical IFC is obtained by oxidation of m-xylene with air in the environment CH3COOH at a temperature of 100 - 130oC and a pressure of 0.07 to 3.5 MPa. As the catalyst used is a salt of cobalt with the addition of the promoting component of acetaldehyde. The oxidation is carried out in two stages SUB>3COOH. The disadvantage of this method is the low productivity of the process.

According to another widespread in industrial scale method, synthesis of high-purity IFC carried out in two stages. The first stage involves the oxidation of m-xylene with oxygen in the environment CH3COOH in the presence of a cobalt-manganese-bromides catalyst at an elevated temperature (170-215oC) and a pressure of 1.5-2.5 MPa with obtaining IFC raw. The second stage involves the purification of crude isophthalic acid method hydrogenation with molecular hydrogen impurities mainly m-carboxyanhydride (m-KBA). The hydrogenation reaction is carried out in aqueous medium in the presence of a catalyst, palladium on coal (Pd/c) at relatively high temperatures (up to 280oC). The process has increased efficiency and achieving high quality IFC: the content of m-KBA 0,0025%, the indicator color 10oN.

The disadvantages of this method include the use of different nature of chemical reactions (synthesis step is used, the oxidation and the cleanup phase - hydrogenation), which entails the use of different solvents, catalysts and other reagents which generate inevitably produce large quantities of liquid and solid wastes and operating conditions of the installations of large capacity creates conditions for the formation of environmental pressures.

Also known is a method of obtaining terephthalic (TPA) or isophthalic acids of higher quality by liquid-phase oxidation of para - or meta isomers of xylene with oxygen in two stages in the environment CH3COOH. On the first stage of the oxidation is carried out at 200-215oC and a pressure of 2.0 to 2.6 MPa, on the second stage at a temperature of 180-200oC and the reaction mass is treated simultaneously oxygen-containing gas mixture leaving the first stage, and phlegm, taken from a zone speed of crystallization and having in its composition 80-88% CH3COOH, 10-16% H2O, 1,5-4,0% aliphatic compounds of General formula

R1- O - R2or

R1, R2: (-CH3or (H) or (-CH3O)

The mass ratio of phlegm: the reaction mixture is 0.3 to 0.6: 1. The content of m-KBA in the resulting IFC is within 0,006 - 0,018%.

One advantage of this method is that IFC monomer purity is obtained without the use of complex methods of purification, for example, by hydrogenation of the impurities using Pd/c. However, as with other previously described methods, this method is not without disadvantages. The most significant of them is that by improving the quality of IFC, i.e., when the content decrease in n is also obtained as the IFC ([m-KBA] = 0,006-0,018%) does not meet the requirements requirements for high-purity IFC ([m-KBA] 0,0025%), which limits the ability to receive IFC.

The closest in technical essence and the achieved results is the method of obtaining highly pure isophthalic acid liquid-phase catalytic oxidation of m-xylene in acetic acid oxygen-containing gas in two stages, followed by purification of the obtained IFC by treatment with acetic acid at a temperature of 100-150oC (prototype). On the first stage of the oxidation is carried out at 180-210oC in continuous flow in the reactor O2-gas and the reaction mixture containing acetic acid, m-xylene in 1-15 times the amount of solvent, cobalt-manganese-promeny the catalyst at a total concentration of cobalt and manganese 500-1500 ppm, the atomic ratio of the metals to the bromine 0.5 to 1.5, to achieve the content of m-KBA in oxidation products 500-10000 ppm and the total concentration of terephthalic acid in the reaction mass 10-35%.

In the second stage, the mixture is optionally oxidised to O2-gas before the formation of isophthalic acid, containing from 0.01 to 0.08% m-KBA.

Next raw IFC obtained in the second stage, mixed with acetic acid and under conditions of mixing and holding tecala Hazen) 20oN. One disadvantage of this method is not sufficiently high quality of the purified IFC. According to modern requirements of consumers that produce high-quality polymeric materials, the rate of color should not exceed 10oN, and the content of m-KBA 0,0025%. In addition, the duration of the oxidation reaction on the first and second stages ~ 80 min indicates the relatively low productivity of the process at the stage of synthesis of technical IFC.

The aim of the present invention is to improve the efficiency of the process and improve the quality of the target product IFC.

The objective is achieved by a combination of two interrelated processes of oxidation of m-xylene in acetic acid and recrystallization technical IFC in acetic acid-water solvent and/or water, in the composition of the oxidation catalyst further added lithium chloride (LiCI) or its mixture with chlorine compounds XCInwhere X Is Mn, Co, H, n=1,2 in the ratio of Cl:Br= 1: 1-1,9 when the total concentration of atoms of Halogens 350-900 ppm, and the atomic ratio of the metal components of the catalyst support within Mn: Co = 1: 0.1 to 2, with their total concentration in the reaction mass 280-800 ppm and p the e above 198oC for 30-45 minutes until a residual concentration of m-carboxybenzene in oxidation products 0,3-0,7%, in the second stage of the oxidation is carried out at a temperature of 170-190oC for 5-15 min to achieve a residual concentration of m-KBA in oxidation products 0,15-0,25%, and then isolated from Okidata technical IFC is subjected to recrystallization in acetic acid-water solvent containing 2-12% H2O, and/or in the water, by heating (20-35%) suspension IFC to 185-220oC, then cooling in four stages up to 30-70oC with a speed of 2-5oC/min, and the selection of high-purity IFC known techniques.

Use in the composition of the Mn-Co-Br catalyst as an additional component (components) of chlorine-containing compounds, specifically LiCI or mixtures thereof, with the chlorides of manganese, cobalt or HCI (LiCI+MnCl3) (LiCI+CoCl3), (LiCI+HCI) found in the range of concentrations and ratios of metal atoms of the catalyst, bromine and chlorine are allowed to increase the rate of conversion of m-xylene in IFC, i.e., to improve the performance of the oxidation process, and also to reduce the amount of intermediate products in the IFC.

The combination was found of the catalyst composition with an effective mass transfer in straw (power density on mixing, given the linear gas velocity in the cross section of the reactor, the dispersed input of reagents and other ), which ensures rapid mixing (homogenization) in the reaction zone, has significantly improved the quality of IFC on the content of high-boiling by-products of the reaction, with coloring and evaluated by the indicator color. This opened up the possibility of purification obtained IFC simple physical method recrystallization in acetic acid-water solvent and/or water with obtaining high purity of the target product (the content of m-KBA 0,002%, chromaticity 10oN), eliminating the use of complicated and expensive purification processes that currently use in industrial practice.

Below is a description of the installations, experimental techniques and examples to help explain the essence of the present invention.

Description of facilities and experimental techniques.

Obtaining high-purity IFC carried out on a laboratory and industrial installations in continuous mode. Reactors (Vlab.= 1.25 l, Vprom.= 1.25 m3) made of titanium and equipped with a pipe mixers, reverse refrigerators - condensers, heating elements, instruments for regulated what About the waste from the reactor gases. Charged to the reactor 95-98% CH3COOH, acetates of manganese, cobalt and adjuvants bromine - and chlorine-containing compounds in the form of HBr and LiCI or mixture (LiCI+MnCl2), (LiCI+CoCl2) (LiCI+HCI). The contents of the reactor when operating the mixer is heated in a current of inert gas to a temperature 170-198oC and start the dosage of the original mixture. At the same time in the reactor serves the air in the quantity, ensure the achievement of given velocity in the cross section of the reactor of 2.5-8 cm/s and the oxygen content in the exhaust from the reactor gases 3-5% by volume. For a fixed (specified) air consumption maintaining the required concentration OF2in the exhaust gases is performed by changing the filing of the original reaction mixture (IRS) in the oxidation reactor or the concentration of m-xylene in the original reaction mass. Oxidat after the first stage is subjected to additional oxidation in the second stage, and then cooled to 30-70oC and filtered. In laboratory conditions, the filtering is carried out on a Buechner funnel, in industrial conditions on the horizontal filtering centrifuge type PGN.

Dedicated pasta (sludge) technical IFC diluted 90-98% acetic acid in reulatory equipped with a mixer, receiving 20-35% WM is Le, equipped with a turbine stirrer and heating elements, and then cooled to 30-70oC with a speed of 2-5oC/min in the same apparatus (laboratory setting) or 4 sequentially installed molds (industrial setting).

The cooled suspension IFC filtered in the laboratory on a Buechner funnel, in industrial conditions in the centrifuge type PGN. Sediment-paste high - cochiti IFC dried to constant weight in a drying Cabinet (laboratory setting) or in the dryer type Venule (industrial setting), and then analyze its quality. In the Parliament of experiments technical IFC is recrystallized in water in the above-described method or sequentially in acetic acid and then in water.

The results of the experiments are presented in table 1 (examples 1 to 17).

Example 1. The process of obtaining IFC conducted in a laboratory setup (Vreactor1.25 l).

Prepare the initial reaction mixture (IRS) in the amount of 2500 ml (2632,94 g), which use acetic acid (1886 ml), m-xylene (570 ml), acetate tetrahydrate manganese (is 3.08 g), acetate tetrahydrate cobalt (1.78 g), lithium chloride (0.85 grams), 40% Hydrobromic acid (2.5 g) and water (134 ml). At the donkey analyze the following composition IRS:

m-xylene - 18,73%

CH3COOH - 74,52%

H2O - 6,64:

Mn - 262 ppm

Co - 160 ppm

Li - 49 ppm

Cl - 269 ppm

Br - 380 ppm

Before oxidation in the reactor is poured a solution of catalyst (without m-xylene), and IRS pour into a collection of stainless steel, equipped with a heating jacket and a transmitter from which the pump is continuously fed into the reactor. After sealing the reactor an inert gas (nitrogen) install a pressure of 1.6 MPa and heated to 196oC when incorporated into the turbine stirrer and a continuous flow of nitrogen.

After reaching the specified temperature in the reactor include the metering pump and from the collector continuously served the IRS in the amount of 1100 ml, which corresponds to a residence time of 35 minutes at a time from the compressor discharge air.

The time of mixing (homogenization) of 1.5 to achieve the establishment of speed stirrer (1800 rpm) at a flow rate of air ~12 nl/min, which corresponds to a linear gas velocity in the cross section of the reactor 4.2 cm/s

The water concentration in the reaction zone is maintained at 8.5% by partial drainage of flooded phlegmy after the second condenser mounted above the reactor. The village is erdie oxidation products. Analysis of selected solid product showed the following quality raw IFC after the first stage of oxidation:

[m-KBA] = 0,68% (6800 ppm)

[m-TC] = 0,59% (5900 ppm)

[Bq] = of 0.03% (300 ppm)

Chroma = 21oH

Oxidat after stage I are finally oxidized in the reactor of the second stage under the following conditions: temperature 185oC, a pressure of 0.9 MPa, time 15 additional oxidation min Analysis of isolated products after oxidation reactor stage II showed the following quality raw IFC:

[m-KBA] = 0,16%

[m-TC] = 0,18%

[BQ] = 0,06%

Chroma = 13oN

Next, the resulting technical IFC was subjected to purification by recrystallization in 95% acetic acid. In the apparatus, the solvent prepare a 20% suspension in a current of inert gas (nitrogen) at a pressure of 1.6 MPa heated to 198oC to dissolve crystalline IFC, after which the solution is cooled to 40oC with a speed of 5oC/min

From the cooled suspension allocate net IFC and get the product of the following qualities:

[m-KBA] = 0,0021%

[m-TC] 0,005%

[BQ] 0,005%

Color = 6oN

Output IFC amounted to 95.8% of theory. Other indicators of the process of example 1, as well as the conditions and results of examples 2-17 are shown in table 1.

oN to 5oN. However, loss of CH3COOH due to combustion at the stage of oxidation increased from 37 kg/t IFC to 42 kg/t IFC.

Example 3. The experience I spend the conditions of example 1 with the only difference that at the stage of oxidation, the ratio of Mn: Co increase from 1:0.6 to 1: 0,1. and at the stage of cleaning using 2-fold recrystallization, first in CH3COOH, and then in H2O. As follows from the results of a 10-fold increase of the manganese content in relation to the cobalt in the catalyst reduced the "combustion" CH3COOH with 37 kg/t IFC to 32 kg/t IFC, however, the quality of raw IFC has somewhat deteriorated and required to carry out a double recrystallization.

The result is a high quality product: the content of m-KBA 15 ppm, the total content of m-Truelove and benzoic acids did not exceed 10 ppm, color 8oN.

Example 4. The experience is conducted under the conditions of example 2 with the only difference that the temperature at the stage of oxidation is reduced to 190oC, and the residence time increased from 35 to 40 min by reducing the filing IRS. At the stage of purification using 2 - fold recrystallization: first in CH3COOH, then H2 the transformation of m-xylene in IFC, that requires a double recrystallization. At the same time, the loss of CH3COOH due to combustion are reduced from 42 kg/t IFC to 29 kg/t IFC. The resulting product meets the requirements of high-purity IFC: [m-KBA) = 20 ppm, the rate of color 9oN.

Example 5. The experience is conducted under the conditions of example 4 with the only difference that the temperature of oxidation is increased to 198oC, and at the stage of purification using a single recrystallization in water. The resulting product meets the requirements of high-net IFC: [m-KBA]=20 ppm, [m-TC] 80 ppm, color 10oN.

The combustion of CH3COOH increased from 29 kg/t IFC to 48 kg/t IFC.

Example 6. Conditions of experience corresponds to example 1 with the pouring of the difference that the concentration of the catalyst increased 1.9 times, and at the stage of purification using a single crystallization in CH3COOH. The result: a high quality product ([m-KBA] = 16 ppm, color 6oN). Loss of CH3COOH due to the combustion increased from 37 kg/t IFC to 46 kg/t IFC.

Example 7. Conditions of experience is similar to example 1 with the only difference that the ratio of Cl: Br alter from 1:1.4 to 1:1,9. The quality of IFC and losses of the solvent close to the results of example 1. The combustion of CH3COOH SOS is W ill result in the conditions of example 1 with the only difference being the ratio of Cl:Br increases from 1:1.4 to 1:0,5, i.e. increase in ~ 3 times the chlorine content relative to the bromine while maintaining the total concentration of ions of Halogens. The results showed a sharp deterioration in the quality of IFC, the reduction in the depth of the transformation of m-xylene in IFC.

Qualitative indicators purified IFC ([m-KBA] = 360 ppm, [m-TC] = 271 ppm, color 56oN) content of intermediate products exceeds by more than an order valid their concentration, and color - more than 5 times.

Example 9 (comparative). Conditions of experience is similar to example 3 with the only difference that the ratio of Mn:Co increase from 1:0.1 to 1:0,05, i.e. increase the Mn content and the composition of the catalyst without changing their total concentration. The results obtained show a decrease in activity of such a composition of Mn-Co-Hal catalyst, which leads to deterioration of quality of the received IFC: [m-KBA] = 210 ppm, color 19,4oN.

Example 10 (comparative). The experience is conducted under the conditions of example 1 with the only difference that the depth of the transformation of m - xylene to IFC on the first and second stages of oxidation increases to a residual content of m-KBA IFC (less than 0.3% in the first stage and less than 0.15% of PA second stage) by increasing the credits required quality of high-purity IFC, however, loss of CH3COOH due to thermal oxidative degradation increase to 80 kg/t IFC.

Example 11. The experience carried out in an industrial reactor (V = 1.25 m3), equipped with two turbine agitators, two capacitors-refrigerators, jacketed for heating, pipes input and output of reagents, Instrumentation. Conditions of experience is similar to example 1 with the only difference that the time of mixing (homogenization) of the reactants in the reactor 12 with two glands at the height of the initial reaction mixture and the above linear air velocity in the cross section of 7 cm/sec.

From the results of example that in the devices of industrial scale are reproduced data of the laboratory setup. Net product that meets consumer demands IFC: [m-KBA] = 18 ppm (m-TC) 5 ppm color 6oN.

Example 12 (comparative). The experience is conducted under the conditions of example 11 with the only difference that the time of mixing (homogenization) is increased to 40 C. By reducing the speed of the mixer, reducing the number of inputs IRS and reduced reduced gas velocity in the cross section of the reactor to 1.1 cm/s

In these conditions, the quality of IFC significantly worse pokazanija in a laboratory setup in the conditions of example 1 with the only, the difference is that the composition of the catalyst exclude the lithium chloride.

The oxidation results showed that the content of the intermediate compounds in the technical IFC allocated after the first and second stages of oxidation, increased ~ 1.2 times. This indicates a decrease in the degree of transformation of m-xylene and IFC and deterioration in the quality of technical

1. Method of production of high-purity isophthalic acid (IFC) by step liquid-phase oxidation of m-xylene with oxygen in the acetic acid medium at elevated temperature and pressure in the presence of salts of cobalt, manganese and bromine compounds, followed by a hot rinse selected crystalline oxidation products of acetic acid, wherein the high-purity IFC is obtained by combination of two interrelated processes of oxidation of m-xylene in acetic acid and recrystallization technical IFC in acetic acid-water solvent and/or water, in the composition of the oxidation catalyst further added lithium chloride (LiCl) or its mixture with chlorine compounds XClnwhere X Is Mn, Co, N, n = 1, 2, in the ratio of Cl : Br = 1 : 1oC 1,9 when the total concentration of atoms of Halogens 350 - 900 ppm, and the atomic ratio of the components of metallo 280 - 800 ppm, and the process of liquid-phase oxidation in the first stage is carried out at the time of mixing of the reactants 12, the temperature not exceeding 198oC (preferably 189 - 197oC) for 35 to 45 minutes until a residual concentration of m-carboxyanhydride (m-KBA) in the oxidation products of 0.3 - 0.7 wt.%, in the second stage of the oxidation is carried out at a temperature of 170 - 190oC for 5 - 15 min to achieve a concentration of m-KBA in oxidation products 0,15 - 0,25%, and then isolated from Okidata technical IFC is subjected to recrystallization in acetic acid-water solvent containing 5 to 12% H2Oh, and/or in the water, by heating 20 - 35% suspension IFC to 185 - 220oC, then cooling in four stages up to 30 - 70oC with a speed of 2 to 5oC/min, and the selection of high-purity IFC known techniques.

2. The method according to p. 1, characterized in that the time of mixing (homogenization) entered into a zone of oxidation reagents maintained within the range of 1 - 12 by setting the feed speed OF2gas (air) into the reaction zone, ensuring the achievement of the given linear velocity in the cross section of the reactor of 2.5 - 8 cm/s

3. The method according to PP.1 and 2, characterized in that the cleaning process technical IFC done by the clinical topics the cleaning process technical IFC carry twice its recrystallization, the first recrystallization is carried out in acetic acid, and the second in the water.

 

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9 cl, 3 dwg, 5 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: method and composition for selective removal of iron solvent oxide from surface of titanium parts without damaging them.

SUBSTANCE: method comprises steps of adding to distillation tower organic acid such as alkyl mono-carboxylic acid having 2 - 6 C atoms or benzoic acid or their mixture at first temperature range 30 -125°C; passing said organic acid through distillation tower at absence of molecular oxygen; adding to organic acid of first temperature and without molecular oxygen aqueous solution of hydro-halide acid whose temperature is less that said first temperature for preparing aqueous solution of solvent composition at second temperature that is less than first temperature; providing contact of titanium part and solvent composition in distillation tower at absence of molecular oxygen.

EFFECT: possibility for selective removal of iron oxide from surface of titanium parts without damage of said parts.

18 cl, 1 dwg, 6 tbl, 14 ex

FIELD: chemical industry; petrochemical industry; methods of extraction of the unreacted xylene from the acetic acid at production of the terephthalic or isophthalic acid.

SUBSTANCE: the invention is pertaining to the field of production of the terephthalic or isophthalic acid by oxidation of the corresponding alkyl benzene, in particular, to the stage of separation of the reaction mixture including the acetic acid in the capacity of the dissolvent. The method is intended for extraction of the unreacted para-xylene or meta-xylene at the regeneration of the acetic acid using isobutyl acetate as the azeotropic agent for dehydration of the acetic acid. From the azeotropic distillation column at the temperature of 94-100°С separate the fraction containing the para-xylene or meta-xylene, which is fed into the run-down tank, where separate the aqueous phase from the organic phase. In the azeotropic section of the azeotropic distillation column determine the ratio of the para-xylene or meta-xylene and the isobutyl acetate in the stored fraction of the organic phase and periodically remove the accumulated part of the organic phase until the mass ratio of the concentrations of the para-xylene or meta-xylene and the azeotropic agent attains the interval from 0.5 up to 6. As the version of realization of the method route the circulation of the part of the accumulated fraction of the organic phase from the run-down tank to the azeotropic column. The technical result of the invention is upgrade of the production process of regeneration of the acetic acid and the unreacted alkylbenzene using the phase of the azeotropic distillation of xylenes from the acetic acid.

EFFECT: the invention ensures the upgrade of the production process of regeneration of the acetic acid and the unreacted alkylbenzene using the phase of the azeotropic distillation of xylenes from the acetic acid.

8 cl, 4 tbl, 5 dwg

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to an improved method for synthesis of halogenphthalic acid. Method involves mixing from 3 to 7 weight parts of acetic acid with 1 weight part of halogen-ortho-xylene, with from 0.25 to 2 mole% of cobalt source as measured for above said halogen-ortho-xylene, with from 0.1 to 1 mole% of manganese source measured for above said halogen-ortho-xylene, with from 0.01 to 0.1 mole% of metal source as measured for above said halogen-ortho-xylene wherein this metal is chosen from zirconium, hafnium and their mixtures, with from 0.02 to 0.1 mole% of bromide source as measured for above said halogen-ortho-xylene wherein halogen-ortho-xylene is represented by the formula (IV): wherein X represents halogen atom. Method involves holding the reaction mixture under pressure 1600 KPa, not less. At temperature 130-2000C, addition of molecular oxygen-containing gas to the reaction mixture in consumption 0.5 normal m3 of gas/h per kg of halogen-ortho-xylene in the reaction mixture for time sufficient for 90% conversion of halogen-ortho-xylene to yield halogenphthalic acid. Also, invention relates to a method for synthesis of halogenphthalic anhydride by distillation and dehydration of halogenphthalic acid, and to a method for synthesis of polyesterimide that involves interaction of halogenphthalic anhydride with 1,3-diaminobenzene to yield bis-(halogenphthalimide) of the formula (II): wherein X means halogen atom, and interaction of bis-(halogenphthalimide) of the formula (II) with alkaline metal salts of dihydroxy-substituted aromatic hydrocarbon of the formula (IV): OH-A2-OH wherein A2 means a bivalent radical of aromatic hydrocarbon to yield polyesterimide.

EFFECT: improved method of synthesis.

20 cl, 2 tbl, 5 ex

FIELD: process for continuous production of terephthalic or isophthalic acid by liquid phase oxidation of respective aromatic dialkyl hydrocarbon.

SUBSTANCE: in order to prepare reaction solvent at least part of mother liquor separated from produced acid is used. Oxidation catalyst concentration in mother liquor is measured beforehand and then oxidation catalyst concentration is continuously corrected due to direct control (regardless of water content). Predetermined quantities of solvent and aromatic hydrocarbon as raw material are continuously supplied to oxidizing reactor for oxidizing aromatic hydrocarbon by means of molecular oxygen. Water concentration in condensate returned from reactor is measured and controlled by means of discharged quantity of returned condensate for stabilizing water concentration in reaction system in order to obtain in the result dicarboxylic acid. Oxidation temperature is sustained stable due to controlling pressure; oxygen concentration in exhaust gas is sustained stable due to controlling feed of oxygen containing gas.

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

FIELD: chemistry.

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

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

2 ex

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