Stepped counterflow catalystic oxidation of disubstituted benzene

FIELD: chemistry.

SUBSTANCE: invention relates to a continuous stepped counterflow method of catalytic oxidation in a solvent of at least one benzene compound, containing two substituting groups, which are selected from alkyl, hydroxyalkyl, aldehyde, carboxyl groups and their mixtures, which can be oxidised to the corresponding acid derivative, involving the following steps: (a) introducing a mixture of material into the first oxidation step, containing at least part of the total amount of each of: (i) solvent, which is an organic acid, (ii) at least one catalytically active metal, selected from manganese, cobalt, nickel, zirconium, hafnium, cerium and their mixtures, and (iii) bromine in molar ratio, in terms of all catalytically active metals, in the interval from 1:20 to 5:1 and from 7 to 60 wt % of the total amount of at least one disubstituted benzene, introduced at steps (a) and (d); (b) partial oxidation of at least one disubstituted benzene at the first oxidation step in the presence of a gas, containing molecular oxygen initially in amount of 3 to 20 vol. %, at temperature ranging from 121°C to 205°C and relative quantities of disubstituted benzene, catalytic metal, solvent and bromine, introduced at step (a), so that from 25 to 99.95 wt % disubstituted benzene, added at the first oxidation step, is oxidised with formation of a gaseous mixture, containing unreacted molecular oxygen, evaporated solvent and a first mixture of products, containing acid derivative, partially oxidised disubstituted benzene, unreacted disubstituted benzene and solvent, and at pressure from 8.96·105 to 14.8·105 Pa, sufficient for keeping disubstituted benzene, partially oxidised disubstituted benzene, acid derivative and solvent in liquid state or in form of a suspension of solid substance in a liquid, so that concentration of residual molecular oxygen in the remaining gaseous mixture ranges from 0.3 to 2 vol. %; (c) extraction of the obtained first product mixture after the first oxidation step and supplying at least part of the extracted first product mixture to the second oxidation step; (d) supplying gas to the second oxidation step, containing molecular oxygen and residue form total amount of disubstituted benzene, catalytic metal, solvent and bromine; (e) oxidation at the second oxidation step of partially oxidised disubstituted benzene and unreacted disubstituted benzene, supplied to the second oxidation step, with a gas containing molecular oxygen in amount of 15 to 50 vol. %, at temperature ranging from 175°C to 216°C and relative quantities of disubstituted benzene, partially oxidised disubstituted benzene, catalytic metal, solvent and bromine, introduced at step (a), so that from 96 to 100 wt % disubstituted benzene and partially oxidised disubstituted benzene is oxidised with formation of a gaseous mixture, which contains unreacted molecular oxygen, evaporated solvent and a second product mixture, containing acid derivative and solvent, and at pressure from 11.7·105 to 16.2·105 Pa so as to keep the acid derivative, partially oxidised disubstituted benzene and unreacted disubstituted benzene mainly in liquid state or in form of a suspension of solid substance in a liquid, so that concentration of residual molecular oxygen in the remaining gaseous mixture ranges from 3 to 15 vol. %; (f) extraction after the second oxidation step of the second product mixture, containing acid derivative; and (g) tapping gas which contains residual molecular oxygen after the second oxidation step and returning it to the first oxidation step.

EFFECT: method allows for maximum use of oxygen without reducing quality of the desired carboxylic acid using a stepped counterflow oxidation system.

25 cl, 11 tbl, 29 ex, 3 dwg

 

The technical field

This invention relates to an improved method of oxidation with the aim of turning one or more aromatic hydrocarbons containing capable of oxidation of substituents into the corresponding derivatives of acids and more specifically relates to such a method, which includes the step of oxidation and the return of residual oxygen from the second stage of oxidation in the first stage of oxidation.

The level of technology

It is well known that aromatic hydrocarbons containing at least one and preferably two or more substituents, are able to oxidize, can be converted into carboxylic acids by increasing the efficiency of oxidation of such groups by molecular oxygen in controlled conditions. Such conditions usually include the use of known oxidation catalyst with a suitable solvent.

Currently, for the industrial production of aromatic acids such as terephthalic acid, essential that the oxygen partial pressure in the reactor during the oxidation of alkylaromatic compounds was high enough to prevent a lack of oxygen. High partial pressure of oxygen reduces the formation of undesirable colored by-products by suppressing reactions combination. In addition, the high p is realnoe pressure can increase the rate of oxidation, that increases the performance of the reactor and reduces the amount of solvent in which carry out the reaction. However, the industrial implementation of such oxidative systems is a significant loss of oxidative capacity due to the lack of molecular oxygen. Therefore, it is highly desirable to increase the utilization of oxygen and thereby increase the efficiency of the method, to eliminate bottlenecks and increase the kinetic parameters of these industrial systems oxidation and at the same time to maintain a high quality of carboxylic acids.

Spillar and others, U.S. patent No. 2962361 (29 November 1960), discloses a stepped continuous countercurrent system "capable of almost quantitatively to use oxygen... without a noticeable decrease in the yield or quality of product. The highest concentration of oxygen is introduced at the last stage and exhaust gas after each stage return in the previous stage, while the partially oxidized products move from the first stage to the last. Also revealed that the last stage of the oxidation is preferably carried out at the highest temperature, pressure and oxygen concentration. It is also shown that at the first stage of oxidation 11 and on line 26, after her at Figure 2, you can enter additional air or oxygen through the line 41 is for to the oxygen concentration in the receiver 24, the refrigerator 23 or line 26 does not exceed 8% vol. (it is preferable that it be equal to zero)". Baldwin and others, U.S. patent No. 3092658 (from 4 June 1963), open graded continuous countercurrent oxidation system, very similar to the system in the specified U.S. patent No. 2962361.

Baldwin, U.S. patent No. 3064044 (November 13, 1962), also reveals the step-countercurrent oxidation system. Nscontainerframe exhaust gases after the second stage back to the first stage of oxidation, and in the patent States that they must contain less than 8% vol. oxygen, but may contain about 1-8% oxygen and, therefore, enter on lines 14 and 15 to provide oxygen in the vessel 11. In the first stage of oxidation 11, the refrigerator 20 and receiver 21, through which the exhaust gases, the patent also indicates that "the number of incremental air, introduced through line 15, should be adjusted so that the oxygen content in gases in the refrigerator 20 and receiver 21 was less than 8%, preferably about zero".

June and others, patent No. 6153790 (28 November 2000), discloses a method of obtaining a dicarboxylic aromatic acids, at least 97% purity. The method comprises contacting in the hull reactor with stirrer dialkylamides aromatic compounds in the solvent is an organic acid with an oxidant, containing at least 50 vol.% oxygen at a partial pressure of oxygen of at least 1 pound per square inch abs. at a temperature of from about 176°F to about 266°F in the presence of a catalytic system containing zirconium and cobalt. The flow of steam, solvent and organic acid, water vapor and unreacted oxidant, away from the reactor. Need more than 50 vol.% oxygen in the oxidizer, so that the total pressure of the reaction system may be low enough to provide cooling phlegmy from the reaction system to a temperature of from about 176°F to about 266°F due to the evaporation of components of the liquid phase with the formation of the above-mentioned steam flow. The design of the reactor should effectively provide almost complete absorption of oxygen below the boundary between the liquid/gas. In order to avoid formation of flammable vapor-gas mixture, it is possible to introduce a sufficient amount of nitrogen near the interface liquid/gas. The patent discloses that, if desired after dilution with nitrogen unabsorbed oxygen can enter in contact with the flows of raw materials in the area before the reactor to use almost all or all the oxygen.

Turner and Hously, patent application No. U.S. 2001/0007910 A1 July 12, 2001; PCT/US 01/20109 of July 18, 2002, published as WO 02/055468 A1; PCT/US 01/00825 from July 19, 2001, published as WO 01/51442 A2; and PCT/'s 01/19960 of July 18, 2002, published as WO 02/055467, open way-way catalytic liquid phase air oxidation of a suitable precursor, for example, paraxylene, carboxylic acid, for example, terephthalic acid, including oksigenirovannym flow of raw materials containing acetic acid and the oxidation catalyst at elevated pressures of from 2000 to 20000 kPa at a continuous and simultaneous submission oxygendemanding flow of raw materials and paraxylene in the first reaction zone upward flow of the traditional reactor oxidation with the formation of the reaction medium, in which the mass ratio of acetic acid to the paraxylene is in the range from 10:1 to 20:1 and the reaction products remain in solution. In this first reactor, the oxygen absorption reaction medium in the first reaction zone is limited to values less than 50% of the oxygen required for full conversion of present paraxylene to terephthalic acid. After that the reaction mixture is fed from the first oxidation zone in the above-mentioned conventional oxidation reactor and simultaneously the pressure of the reaction mixture in conventional oxidation reactor is reduced to a pressure in the range from 1000 to 2000 kPa. In WO 01/51442 A2 discovered a way to improve the performance of conventional oxidation reactor, while three other patent publications disclose methods reduced the I level of impurities in the final carboxylic acid and regulation of decomposition of the solvent and predecessor.

Although it is highly desirable to maximize the oxygen and thereby increase the efficiency of the method and to increase the speed of reactions in the industrial oxidation system while maintaining the high quality of carboxylic acids without the use of additional pressure, this goal has never been achieved and the means of its achievement has never been disclosed.

The INVENTION

The present invention represents an improved continuous speed way catalytic oxidation in the presence of a solvent at least one benzene ring compounds containing two substituting groups that can be oxidized to the corresponding acid, which is selected from the class consisting of alkyl, hydroxyalkyl, aldehyde, carboxyl groups or mixtures thereof. This method comprises the steps: (a) introduction in the first oxidation zone is a mixed raw material containing from about 7 to about 60 wt.% from the whole mass of at least one disubstituted benzene introduced into stages (a) and (d), and at least part of the total of the amounts entered in steps (a) and (d), each of the components: (i) solvent, (ii) catalyst components representing at least one catalytically active metal selected from the class consisting of manganese, cobalt, Nickel, zircon is I, hafnium, cerium and mixtures thereof, and (iii) bromide in a molar ratio in the calculation of all catalytically active metals in the range of from about 1:20 to about 5:1; (b) partially oxidized disubstituted benzene in the first zone of the oxidation gas containing molecular oxygen initially in the amount of from about 3 to about 20 vol.%, at a temperature in the range of from about 121°C. to about 205°C. and in such relative amounts of disubstituted benzene, catalyst components and solvent and at a temperature to from about 25 to about 99.95 wt.% disubstituted benzene, is introduced to the first stage of oxidation, were oxidized with the formation of a gas mixture containing unreacted molecular oxygen, evaporated the solvent and the first mixture of products containing unreacted disubstituted benzene, partially oxidized disubstituted benzene, acid derivative and a solvent, and at a pressure sufficient to disubstituted benzene, partially oxidized disubstituted benzene, acid derivative and the solvent remained in the liquid phase or suspension of solids in a liquid and to a residual concentration of molecular oxygen in the final gas mixture ranged from about 0.3 to about 2 vol.%; (C) the allocation of the first formed of the mixture of products of the first stage of oxidation and odaca at least part of the selected first mix of products in the second stage of oxidation; (d.) the feed to the second stage of oxidation with molecular oxygen or gas containing molecular oxygen, and remains above the predefined total of the amounts entered in the stages (a) and (d)disubstituted benzene, catalyst components, solvent and bromine; (e) a substantially complete oxidation in the second stage of oxidation of the partially oxidized disubstituted benzene and unreacted disubstituted benzene, introduced in the second stage of oxidation, in the presence of a gas containing molecular oxygen at a temperature of from about 175°to about 216°C and in such relative amounts of disubstituted benzene, partially oxidized disubstituted benzene, catalyst components and solvent and at a temperature to from about 96 to about 100 wt.% disubstituted benzene and partially oxidized disubstituted benzene was oxidized with the formation of the second mixture of products containing the above acid derivative and a solvent, and at a pressure sufficiently high to acid derivative, partially oxidized disubstituted benzene and unreacted disubstituted benzene remained in the form of liquids or suspensions of solids in liquids, and that the residual concentration of molecular oxygen in the gas exhausted from the second stage of oxidation, ahadees in the range of from about 3 to about 15 vol.%; (f) selection after the second stage of oxidation of the second mixture of products containing acid derivative; and (d) selection after the second stage of the oxidation gas containing molecular oxygen, and his return to the first stage of oxidation.

The present invention also offers a solution or a suspension of solids in liquid, obtained in stage (b).

BRIEF DESCRIPTION of FIGURES

For a more complete understanding of the present invention will refer to the variant illustrated in more detail accompanying drawings and described below by using examples of the invention.

Figure 1 is a schematic illustration of one variant of the method of the present invention that implements a stepwise continuous countercurrent oxidation of paraxylene to produce high-quality terephthalic acid and maximum use of oxygen.

Figure 2 is a series of charts based on full consumption of acetic acid concentration of 4-carboxybenzene in the reactor, which were held many illustrative Examples and comparative Examples below.

Figure 3 is a series of graphs of the dependence of optical density of terephthalic acid after separation, washing and drying on the concentration of 4-carboxybenzene in the reactor, which were held many ill trebuyushie Examples and comparative Examples, below.

It is important to note that figure 1 is the schematic. In some Examples, the details of which are not important for understanding of the present invention or which hamper the perception of other details, can be omitted. Of course, it is understood that the invention is not limited to the specific Examples.

A DETAILED description of the PREFERRED OPTIONS

Components of the mixtures of raw materials for the method of the present invention include at least one aromatic hydrocarbon containing at least one Deputy, which can be oxidized to the corresponding dicarboxylic acid, i.e. an acid derivative. Preferred components of the mixture of raw materials include at least one disubstituted benzene containing any of a variety of substituents, selected from the class consisting of alkyl, hydroxyalkyl, aldehyde and carboxialkilnuyu groups or mixtures thereof. Particularly preferred components of the mixtures of raw materials are paradisaeidae derivatives of benzene containing alkyl groups as substituents, an acid derivative of which is terephthalic acid and partially oxidized form, including mono - and diatomic alcohols and aldehydes, and monocarboxylic acid, for example, p-hydroxymethylbenzene acid, p-Truelove aldehyde and p-Truelove acid. PR is doctitle, to the alkyl groups contain 1-4 carbon atoms, and most preferably a methyl group. Accordingly, particularly preferred component of the mixture of raw materials is paraxylene. At least one disubstituted benzene used in the present invention, it is proposed in the solution of the solvent, preferably an organic acid.

The preferred organic acid containing from one to six carbon atoms plus one carboxyl group, such as benzoic acid. The most preferred solvent is acetic acid due to its vapour pressure at the preferred temperatures of the reactor and properties as a solvent. These organic acids are solvents for reasonable concentrations of the components of raw materials, components of the catalytic system, the intermediate oxidation products and product - dicarboxylic acid. Disubstituted benzene in the raw material composition is preferably in solution with a concentration of from about 5 to about 25 wt.%.

The components of the mixture of raw materials also include at least one catalytically active metal selected from the class consisting of manganese, cobalt, Nickel, zirconium, hafnium, cerium and mixtures thereof, and promotergene substance. Preferably, the catalytically active metals are cobalt and manganese. Catalytically act the main metals may be in any form, soluble in the reaction medium. Examples of such soluble forms are organic acid salts, basic salts, complexes and alcoholate. The catalytically active metals can be added to the reaction mixture together with disubstituted benzene or separately. In the catalytic system used in the present invention, may also be present other metals and promoters. Bromodomain substances can serve as molecular bromine, salt - bromide or bromate, Hydrobromic acid, poslednee organic compound or a mixture of any or all of these compounds.

The oxidant used in the present invention, is oxygen, which in this invention means of molecular oxygen. The source of oxygen in the present invention is usually pure oxygen, air or air with extra oxygen.

At the first stage of oxidation (a) is served from about 7, preferably from about 15 to about 60, preferably up to about 35% of the total number disubstituted benzene, which must be entered in steps (a) and (d). Comparative Example A, below, shows that if step (a) submit all p-xylene for stages (a) and (d), the optical density (1,79) obtained terephthalic acid will be unacceptably high. The optical density at the wavelength of the s 340 nm (OD 340) reflects the concentration of undesirable high molecular weight compounds, which causes a yellow color and fluorescence of the product. It is preferable to apply to the first stage of oxidation of from about 20, more preferably from about 40 to about 100 wt.% above a predetermined total number of each of the catalytically active metals for stages (a) and (d), preferably cobalt and manganese. It is preferable to apply to the first stage of oxidation of from about 20, more preferably from about 40 to about 100 wt.% above a predetermined total number of bromine for stages (a) and (d). It is preferable to apply to the first stage of oxidation of from about 10, more preferably from about 40, preferably to about 100 wt.% the total quantity of solvent for stages (a) and (d).

In the first stage oxidation molar ratio of bromine to the total amount of catalytically active metal is from about 1:20, preferably from about 1:5, more preferably from about 1:4 to about 5:1, preferably to about 2:1, more preferably to about 1:1. The mass ratio of the catalytically active metal to the solvent in the first stage of oxidation is between about 150, preferably from about 400 to about 10,000, preferably up to about 5000 ppm by weight of catalytically active metal per million parts of the solvent. The atomic ratio of manganese to cobalt in the first stage of oxidation is in the range from about 1:100, preferably from about 1:5 to about 100:1, preferably to about 5:1.

The reaction temperature in the first stage of oxidation is in the range from about 121°C. to about 205°C. the Pressure in the first stage of oxidation remains quite high at the reaction temperature to maintain the solvent, partially oxidized disubstituted benzene, acid derivative and unreacted disubstituted benzene in the liquid state or in the form of a suspension of solids in liquid. Typically, the pressure in the first stage of oxidation is in the range from about 130 to about 215 psi (8,96·105is 14.8·105PA).

The oxygen concentration in the oxygen-containing gas supplied to the first stage of oxidation is in the range from about 3, preferably from about 4 to about 20, preferably up to about 11, more preferably up to about 8 vol.% the oxygen. Reaction conditions are chosen so that the concentration of residual oxygen in the gas discharged after the first stage of oxidation, ranged from about 0.3 to about 2, preferably up to about 1 vol.%. In such conditions, about 25, preferably from about 60, more preferably from about 70 to about 99.95 wt.% the disa is placed benzene, supplied to the first stage of oxidation, partially or completely oxidized in the first stage of oxidation. Comparative examples a and b show that the optical density (1,79 and 1.08) obtained terephthalic acid is unacceptably high when the oxygen content in the exhaust gas after the first stage of oxidation is less than 0.3%.

In the second stage oxidation molar ratio of bromine to the total amount of catalytically active metal is from about 1:20, preferably from about 1:5, more preferably from about 1:4 to about 5:1, preferably to about 2:1, more preferably to about 1:1. The mass ratio of the catalytically active metal to the solvent in the second stage of oxidation is between about 150, preferably from about 400 to about 10,000, preferably up to about 5000 ppm by weight of catalytically active metal per million parts of solvent. The atomic ratio of manganese to cobalt in the first stage of oxidation is in the range from about 1:100, preferably from about 1:5 to about 100:1, preferably to about 5:1.

The reaction temperature in the second stage of oxidation is in the range from about 347°F, preferably from about 360°F to about 421°F, preferably to about 401°F. the Pressure in the first stage of oxidation of the remains fairly high at the reaction temperature, in order to maintain the solvent, partially oxidized disubstituted benzene, acid derivative and unreacted disubstituted benzene in the liquid state or in the form of a suspension of solids in liquid. Typically, the pressure in the first stage of oxidation is in the range from about 170 to about 235 psi (11,7·105and 16.2·105PA). The temperature in the first stage oxidation is preferably at least 5.5°C lower than the temperature in the second stage of oxidation. The pressure in the first stage of oxidation of at least 5, more preferably at least 20 psi lower than the pressure in the second stage of oxidation.

The oxygen concentration in the oxygen-containing gas supplied to the second stage of oxidation is in the range from about 15, preferably from about 20 to about 50, preferably up to about 25 vol.% the oxygen. Reaction conditions chosen at specified intervals so that the concentration of residual oxygen in the gas discharged after the second stage of oxidation, ranged from about 3, preferably from about 4 to about 15, preferably up to about 11, more preferably up to about 8 vol.%. In such conditions, the second stage of oxidation is oxidized to about 97, preferably from about 99 wt.% to about 100 wt.% disubstituted benzene and partially oxidized disa is placed benzene, supplied to the second stage of oxidation.

The first stage of oxidation can be carried out in one reactor or in many reactors operating in parallel. Similarly the second stage of oxidation can be carried out in one reactor or in many reactors operating in parallel. Thus, the first stage of the oxidation is carried out in several reactors, for example, in the four reactors can be combined with the second stage of the oxidation is carried out in a single reactor. In this case, a suspension or solution formed in all the reactors of the first stage of oxidation, can be submitted in one reactor of the second stage of oxidation, and oxygen in the exhaust gas from the reactor of the second stage of oxidation can be returned and distributed to the four reactors of the first stage of oxidation. In another embodiment, the first stage of the oxidation is conducted in the same reactor, can be combined with the second stage of the oxidation is carried out in several reactors, for example in the four reactors. In this case, a suspension or solution from one reactor of the first stage of oxidation can be divided and submit to each of the four reactors of the second stage of oxidation.

One variant of the method of the present invention, for which the simulated illustrating Examples 1-18 and comparative Examples a and b, presents the schematic drawing in figure 1. For clarity disubstituted benzene are the two who is paraxylene, the acid derivative is terephthalic acid, and partially oxidized disubstituted benzenes (intermediates oxidation) include parahydroxybenzoic acid, p-Truelove aldehyde, 4-carboxybenzene and p-Truelove acid. The solution of paraxylene and the above-described components of the catalyst in acetic acid is introduced into the first reactor 10 from the container with the raw material 11 through line 12. The contents of the first reactor 10 is thoroughly mixed by the mixer 13, and the pressure in the reactor is maintained at the desired level by the pressure regulator 14 on the discharge line 15 of the first reactor 10. The temperature of the contents of the first reactor 10 handle with the help of the jacket 16 of the first reactor 10. The oxygen fed to the first reactor 10 through lines 17 and 18 in the exhaust gas stream from the second reactor 20. If desired to increase the concentration of oxygen in the gas stream included in the first reactor 10 through line 17 and 18, additional oxygen in the form of compressed air in line 21 can be combined with the exhaust gas stream from the second reactor 20. In another embodiment, to reduce the concentration of oxygen in the gas stream included in the first reactor through line 17, additional nitrogen if desired, can be combined via line 22 with the flow of the gas exhaust from the second reactor 20.

para-Xylene and oxygen react in the first reactor 10 with the formation of RA is down or suspension, containing unreacted para-xylene, intermediate products of its oxidation and terephthalic acid. Excess heat of reaction away by evaporating some of the solvent. The exhaust gas stream containing the vaporized solvent, nitrogen (from air) and unreacted oxygen, is withdrawn from the first reactor 10 through line 25 into the refrigerator 26, where most of the evaporated solvent is condensed and either returned to the first reactor 10 through lines 27, 28 and 29, or passes in the second reactor 20 via lines 27, 28 and 30 and is divided into a first portion that is returned to the first reactor 10 through lines 27, 28 and 29, and a second portion directed to the second reactor 20 via lines 27, 28 and 30. Non-condensable vapors dissipate through the line 33 and line selection 15, and a sample of non-condensable vapor is taken for analysis through the line 36 to control the reaction and to determine the concentration of unreacted oxygen in the exhaust gas.

The level of solution or suspension in a first reactor 10 is supported by a valve 41 between the first reactor and the second reactor 20. The pressure in the first reactor 10 can be maintained higher than in the second reactor 20, so that when you open the valve 41 the resulting solution or suspension is fed from the first reactor to the second reactor 20 through line 42 and 43. In another embodiment, it is possible to use n the SOS (not shown) in line 42 or 43 for pumping solution or suspension from the first reactor 10 to the second reactor 20. If necessary or desired, you can enter the second reactor 20 additional quantities of one or more components of the reaction - paraxylene, one or more components of the catalyst, solvent, and/or bromine, respectively, of the containers 44, 45 and 46, respectively, through lines 47, 48 and 49. Compressed air is injected through the line 50 to the second reactor 20.

If oxidized disubstituted benzene is a p-xylene, the composition of the product after the first stage of oxidation, excluding the solvent as a percentage of the total mixture of products includes from about 5.0 to about 85,0 wt.% terephthalic acid, from about 2.0 to about 20.0 wt.% 4-carboxybenzene, from about 0.0 to about 3.0 wt.% hydroxymethylbenzene acid, from about 5.0 to about 65,0 wt.% p-Truelove acid, from about 0.0 to about 30.0 wt.% p-Truelove aldehyde and from about 0.0 to about to 35.0 wt.% p-xylene.

As in the first reactor 10, the contents of the second reactor 20 is thoroughly mixed using a mixer 53 and the pressure in the reactor is maintained at the required level by the pressure regulator 54 to the drain line 19 from the second reactor 20. The temperature of the contents of the second reactor 20 regulate by means of a jacket 55 of the second reactor 20. Oxygen interacts with unreacted paraxylene and intermediate products of its oxidation in the WTO the second reactor 20 to form a solution or suspension, containing terephthalic acid. The oxidation of paraxylene and intermediate products of its oxidation to terephthalic acid is performed with great fullness in the second reactor 20. The resulting solution or slurry of terephthalic acid is then withdrawn from the second reactor 20 through line 56, the drain valve 57 and line 58.

Excess heat of reaction away by evaporating part of the solvent. The exhaust gas stream containing the vaporized solvent, nitrogen and unreacted oxygen, is withdrawn from the second reactor 20 through line 61 into the fridge 62, where most of the evaporated solvent is condensed and returned to the second reactor through lines 63 and 64. A sample of the condensed solvent is taken for analysis through the line 65. Non-condensable vapor disperses through line 67 and 19, and a sample of non-condensable vapor is taken for analysis through the line 68 to control the reaction and to determine the concentration of unreacted oxygen in the exhaust gas from the second reactor 20.

The resulting solution or suspension obtained aromatic acid, remote from the second oxidation reactor, then usually subjected to crystallization, as described in the aforementioned U.S. patent No. 3092658 in column 2, row 45-63; U.S. patent No. 2962361 in column 2, line 43 to column 3, line 2; and in U.S. patent No. 3064044 in column 3, row 47-71. In one embodiment, actor or suspension of an aromatic acid, abstracted from the second oxidation reactor, are sent to one or more vessels, where they are in contact with the air in the oxidation conditions for the further oxidation of the intermediate impurity. Then the solution or suspension of crystallized as described above. Usually aromatic acid can be distinguished by centrifugation or filtration and then purified by use of a hydrogenation catalyst and water as a solvent, as is well known to specialists.

The present invention is applicable to cleaning any aromatic acids, including well-known methods, Examples of which are described in U.S. patent No. 5354898 and 5362903, both included with references. In General, the purification of aromatic acids include hydrogenation of dissolved crude aromatic acid in the fluid flow for cleaning solvent for dissolving the purified aromatic acid. Then dissolved purified aromatic acid is crystallized and the resulting solid purified acid is separated from the flow of the purified liquid, usually by filtering.

The invention can be used in the method of purification of aromatic acids in which the crude aromatic acid (e.g., crude terephthalic acid) dissolved in the fluid flow for cleaning, solvent, and treated with hydrogen in a reactor under pressure in lane is the first reaction zone in the presence of a hydrogenation catalyst. The hydrogenation catalyst in the reactor under pressure usually contains one or more components of the active hydrogenation catalysts deposited on a substrate. The substrate is usually in the form of granules, although you can use tablets or particles of other shapes. Use granules preferably are medium in size from -2 to -12 mesh mesh (US Sieve Series), more preferably from -4 to -8 mesh mesh. As the carrier of the preferred activated carbon and preferred coconut charcoal. Such activated carbon typically has a surface at least 600 m2/g (N2, BET method), preferably from 800 m2/g to 1500 m2/, Although activated carbon derived from coconut charcoal in the form of granules, is preferred as a carrier for the components of the catalyst for hydrogenation, can be applied to other porous carbons, metal oxides or other carriers or substrates.

The hydrogenation catalyst contains at least one active component in the catalytic hydrogenation. Especially the active components of the hydrogenation catalysts are metals of group VIII of the Periodic table of elements (version upac) including palladium, platinum, rhodium, osmium, ruthenium, iridium and mixtures thereof. Component of the hydrogenation catalyst may be applied or added to the coal or other media any with the special for example, treatment of the carrier with a solution of compounds of one or more metals of group VIII such as palladium chloride, followed by drying to remove excess solvent.

The preferred content of the metal of group VIII on a carrier is in the range from 0.01 to 2 wt.% calculated on the total weight of the final catalyst, i.e. on the total weight of dry coal carrier component and active in the hydrogenation. More preferred is a content of a metal of group VIII in the coal carrier from 0.2 to 0.8 wt.%.

The catalyst layers and catalysts suitable for the variant of the present invention relating to the purification of aromatic acid that is described, for example, in U.S. patent No. 4394299; 4629715; 4728630 and 4892972. A suitable catalyst is palladium on carbon can be obtained, for example, from Engelhard Corporation, Edison, N.J. in Addition, Engelhard Corporation supplies suitable rhodium catalysts on coal.

A suitable reactor for hydrogenation is any reaction vessel, capable of maintaining the temperature and pressure required for the hydrogenation of the crude aromatic acid, dissolved in a solvent for cleaning. The preferred design of the reactor may be a cylindrical reactor, the axis of which is vertical, containing a hydrogenation catalyst in a fixed bed. In a preferred embodiment, neocide the percent aromatic acid, dissolved in a solvent for cleaning, added to the reaction vessel at the top or near the top of the reactor, and the crude aromatic acid, dissolved in a liquid for cleaning, drains flow down through the bed of hydrogenation catalyst contained in the reaction vessel in the presence of gaseous hydrogen and impurities interact with hydrogen. In this preferred embodiment, the aromatic acid is purified and the purified product is removed from the reaction vessel from the bottom or near the bottom of the reactor.

In a suitable reaction vessel a hydrogenation catalyst, preferably containing carbon carrier and the components of the catalyst, active in hydrogenation and deposited on a substrate, is held inside the reaction vessel using a grill or in another way that ensures the presence of catalyst particles in the reactor and a relatively free flow of crude aromatic acid, dissolved in the fluid flow for cleaning. Such methods of maintaining the catalyst particles can be used flat grate or grid consisting of closely spaced parallel wires. Other devices to maintain the catalyst can be, for example, tubular grille Johnson or perforated plate. Device to maintain the catalyst particles izhota is more corrosion-resistant material, possessing sufficient strength to effectively hold the catalyst bed. Best of all, when the device is to maintain the catalyst layer has openings of 1 mm or less and made of metal, e.g. stainless steel, titanium or Hastelloy C.

The reactor can operate in several modes. For example, in the reactor can maintain a certain liquid level and feeding hydrogen at any given pressure in the reactor at a rate sufficient to maintain a certain liquid level. The difference between the actual reactor pressure and the vapor pressure of the liquid for cleaning is equal to the partial pressure of hydrogen in the vapor space of the reactor. In another embodiment, if the hydrogen serves in a mixture with an inert gas such as nitrogen, the difference between the actual reactor pressure and the vapor pressure of a solution of the crude acid is equal to the total partial pressure of hydrogen and impurities inert gas. In this case, the partial pressure of hydrogen can be calculated from the known relative quantities of hydrogen and inert gas in the mixture. In another mode, the reactor can be filled with fluid flow for cleaning, leaving space for steam space. This reactor can function as a hydraulically filled the system with dissolved hydrogen fed to the reactor in the form of a regulation which has been created thread. In this case, the concentration of hydrogen in solution can be changed by setting a particular rate of flow of hydrogen into the reactor. If desired, the partial pressure of pseudopodia can be calculated from the concentration of hydrogen in solution, which, in turn, can correlate with a feed rate of hydrogen in the reactor.

In the mode in which the proposed method is regulated by setting the partial pressure of hydrogen, the partial pressure of hydrogen in the reactor is chosen preferably in the range from 10 psi to 200 psi (69-1379 kPa) or higher depending on the valid passport of a reactor pressure vessel, the extent of contamination above the crude aromatic acid, activity and service life of the specific catalyst and other process parameters understood by the experts. In the mode in which the proposed method is regulated by setting the hydrogen concentration in the raw material solution, this concentration is usually less than the saturation concentration of hydrogen and the reactor itself is hydraulically filled. Thus, set the flow rate of hydrogen in the reactor will lead to the proper regulation of the concentration of hydrogen in solution. In General, the amount of hydrogen that must be submitted to the reactor cleanup under the reaction conditions, certainly should be sufficient to clean the necessary process of hydrogenation.

Space velocity, expressed as the weight of the crude aromatic acid, referred to the weight of catalyst per hour, in the process of hydrogenation is usually from 1 hour-1up to 25 h-1preferably from 2 h-1up to 15 h-1. The contact time of the fluid flow for cleaning with a layer of catalyst will vary depending on the flow rate.

Hydrogenated stream after hydrogenation, containing purified aromatic acid and the solvent is removed from the reactor and cooled to the crystallization temperature. The crystallization temperature must be sufficiently low (for example, 320°F or below)in order to start the crystallization of purified aromatic acid with the formation of crystals within the liquid phase. The crystallization temperature must be sufficiently high to impurities and products of their reduction (hydrogenation products) remained dissolved in the liquid phase. After that, the liquid containing dissolved impurities and products of their recovery, separated (usually by centrifugation or filtration) from crystals of purified aromatic acid.

Especially recommended for use in the method of this invention is to combine it with one or more of the existing reactors oxidation. In this case, one or more of the existing reactors would RA is otati in the second stage of the method of the present invention; while the preliminary oxidation reactor would be installed and used for the first stage in combination with the existing reactor for the second stage. The result would be a significant increase in the productivity of existing reactors without the use of additional air or additional capacity of the compressor without a noticeable decrease in quality or yield of the obtained acid derivative or an additional flow of solvent.

The present invention will be clear upon consideration of the following Examples, which illustrate but do not limit enhanced the oxidation method of the present invention.

Illustrative Examples 1-18 and comparative Examples a and b

The solution of raw materials in each of the illustrative Examples 1-18 and comparative Examples a and b were prepared from measured quantities of solvent (acetic acid and water), catalyst (cobalt acetate, acetate and hydrobromide manganese) and paraxylene (PX) and kept in the boot containers for solvent/catalyst/PX. This raw material was pumped into the first reactor at a given speed. Mixed with the necessary amount of nitrogen and compressed air so that the resulting stream had the same volume and the same oxygen content as the stream of non-condensable steam at the outlet of the second reactor. Thus, the floor is built, the flow of compressed air and nitrogen, fed into the first reactor simulates the composition and volume of the stream exiting the second reactor and fed into the first reactor.

The contents of the first reactor were thoroughly stirred with a stirrer. The pressure in the reactor was maintained at the desired level by the pressure regulator on the discharge line to bleed uncompressed exhaust gas from the first reactor. The temperature of the reactor was controlled by means of the heating jacket of the reactor. The level in the reactor was maintained by opening and closing the valve between the first and second reactors. For the convenience of the experiment the pressure in the first reactor is maintained slightly higher than in the second reactor, so that the substance at an open valve passed from the first reactor to the second due to the difference in pressure.

PX and oxygen are reacted in the first reactor, forming a reaction solution or suspension containing unreacted PX, intermediate products of its oxidation and terephthalic acid is the final oxidation product. The heat released by the reaction, was taken by evaporating part of the solvent. The exhaust stream from the first reactor was sent to the refrigerator, where condense a large portion of the solvent. Condensed phlegm or returned to the first reactor, or passed through the second reactor, or to combine both. Samples of the non-condensable vapor was collected and analyzed to monitor the course of the reaction.

The reaction solution or the suspension is sent from the first reactor to the second reactor. In the second reactor is also provided with a constant speed an additional portion of the solvent and the PX. The amount of compressed air supplied to the second reactor was such that the oxygen concentration in the outlet line from the reactor remained at the right level. Monitoring the second reactor was the same as for the first reactor, except that phlegmy took a small sample to regulate the concentration of water in the contents of the reactor to the desired level. Oxidation of PX and intermediate products of its oxidation in the second reactor is carried out with sufficient completeness. The product terephthalic acid is removed from the second reactor through the drain valve.

Specific reaction conditions and the results of the illustrative Examples 1-18 and comparative Examples a and b are presented in tables 1-7. Symbols PX, Us, NMWA, SWA and VA in tables 1-7 denote, respectively, p-xylene, acetic acid, hydroxymethylbenzene acid, terephthalic acid, 4-carboxybenzene and benzoic acid. The term H2About Konz in the last column of table 1 under the Liquid in the reactor refers to the concentration of water in the first reactor, including the water formed in the oxidation reactor.

Symbol SCFH means standard cubic f is you in an hour. The Us consumption represents the amount of acetic acid consumed in the Sample, expressed in pounds Us a thousand pounds PX (lb/Tyson PX). The ratio of solvent in table 4 are expressed in pounds of solvent per pound PX just in raw materials both reactors (pound rest./pound PX just in raw materials). Symbol OD 340 represents the optical density of terephthalic acid (TA) at a wavelength of 340 nm after separation, washing and filtering.

Comparative Examples 1-9

The method used in Examples 1-18 was also used in the comparative Examples 1-9 except that in comparative Examples 1-9 are not used two oxidation reactor. Used one oxidation reactor, and it was regulated in the same way as the second oxidation reactor used in Examples 1-18. All components of the reaction mixture was injected directly into a single reactor oxidation. Non-condensable vapor from the reactor oxidation was collected from the reactor, as described for the first oxidation reactor in Examples 1-18.

Specific reaction conditions and the results of comparative Examples 1-9 are presented in tables 8-11. Abbreviations and units listed in tables 8-11, the same as in tables 1-7. Comparison of the results of comparative Examples 4, 5, 6 and 7 with the results of comparative Examples 1, 2, 3 and 8 shows that when the oxygen concentration of the exhaust gas was lower by about 1% vol. compared with the normal concentration of about 4 vol.%, the color of the obtained terephthalic acid according to optical density (OD 340) significantly increased, which makes THE unsuitable.

Examples 1-18 shows that when speed countercurrent oxidation is achieved by reduction of oxygen concentration in the exhaust gas to about 1 vol.%, the color of the obtained terephthalic acid, as well as the quantity of acetic acid, becomes comparable with the results of the existing method of oxidation without speed countercurrent oxidation, i.e. about 4% vol. the oxygen. Comparing the results of Examples 18 and 14 shows that the number of disubstituted benzene introduced into the first reactor may be in the range from 20 to 55 wt.% from a pre-defined total number of disubstituted benzene introduced into both reactors. Examples 1-18 show that the gaseous raw material is fed into the first reactor may contain from 4 to 6 vol.% the oxygen. Examples 1-18 show that the temperature of the first reactor may be in the range from 277°F to 321°F. Examples 8 and 17 show that oxidized from about 79 to of 99.3 wt.% disubstituted benzene, is introduced to the first stage of oxidation. From Examples 13 and 14 shows that the residual concentration of molecular oxygen in the gaseous mixture from the first reactor may be in the range from 0.73 to 1.66%vol.

Figures 2 and 3 present the given graphics showing the effect of the concentration of 4-carboxyanhydride (4-CBA) in the reactor oxidation on (a) total consumption of acetic acid (measured in pounds of acetic acid per 1000 pounds of para-xylene) and (b) optical density at 340 nm of the obtained terephthalic acid after separation, washing and drying. The graphs in figure 2 show that the total consumption of acetic acid in experiments on speed countercurrent oxidation is comparable to that according to the experiments without speed countercurrent oxidation, in which the waste stream contained 4% vol. oxygen, when the results are compared at equal wt.% 4-CBA in the obtained terephthalic acid. In addition, the graphs show that if the oxygen concentration in the exhaust gas is reduced to 1% vol. without speed countercurrent oxidation, the amount of acetic acid increases significantly. In this way the graphs in figure 3 show that the optical density in the experiments with stepwise countercurrent oxidation comparable to an optical density in the experiments without speed countercurrent oxidation, in which the waste stream contained 4% vol. the oxygen. In addition, the graphs show that if the oxygen concentration in the exhaust gas is reduced to 1%vol.

without speed countercurrent oxidation, the optical density of the obtained terephthalic acid is mean is Ino above. Thus, from the graphs in figures 2 and 3 it can be seen that the method of the present invention is an economical method of obtaining acid derivative such quality that is comparable or not much different from similar products produced and supplied by the industry at present.

In the practical use of the method of the present invention, the highest acceptable temperature, for example 300°F, in the first oxidation reactor may be limited by the overall process parameters, in particular pressure in the second reactor and the heat balance requirements. When the set temperature limit, it is necessary to accept one or more other variables in order to achieve the oxygen concentration in the exhaust gas is less than or equal to about 2%. Examples include the following variables: the paraxylene content in raw materials, the amount of added catalyst, the contact time and increasing the concentration of catalyst in the reactor while reducing the amount of added solvent. In this sense, in Examples 8 and 9 shows that when the ratio of oxygen to the paraxylene (Oh/PX) in the first reactor is too low (i.e. too much of paraxylene in raw materials, because the amount of oxygen is determined by the volume supplied from the second reactor, and the volume of which it is desirable to take out first the reactor), such a result is less desirable because a significant amount of paraxylene remains unreacted and the color of the obtained terephthalic acid becomes more intense (of 0.58 and 0.56, respectively). Similarly, since all the exhaust stream from the first reactor is sent directly to the second reactor, the entire catalyst introduced into the first reactor, gets to the second reactor. Therefore, the amount of catalyst is determined by the need for the catalyst in the second reactor and thus is not fully independent value for the first reactor. Moreover, when the same performance, increased contact time can be achieved by increasing the volume of the reactor, but this may not be desirable because it increases the costs. In addition, after the second reactor, the greater part of the solvent is separated from the product and returned to the process. This stream of recycle solvent (stock solution) also contains a large part of the return of the catalyst. The amount of catalyst without solvent, which should be added to the reactor is small. Therefore, it is impossible to significantly reduce the amount of solvent added to the first reactor, not reducing at the same time the amount of the catalyst.

In contrast, a very convenient way to simultaneously improve the con is entrale catalyst and the contact time in the first reactor is the submission of all or part of the condensed phlegmy from the first reactor to the second reactor, bypassing the first reactor. As a result, the amount of solvent in the first reactor is reduced and the concentration of the catalyst and the contact time in the first reactor increases. Examples 2 and 6 show that in this way it is possible to lower the temperature of the oxidation (and get only about 1% vol. oxygen in the exhaust gas from the first reactor. Product color OD 340 (0.34 and 0.29) and the consumption of acetic acid (37 and 38 lb/Tyson PX) are acceptable.

Table 1
Conditions in the first reactor
Example No.The composition of raw materials (mass. share)The feed rate (lb /h)Feed rate PX(lb /hour)The composition of the liquid in the reactor
conc-s PXconc-s Usconc-s H2OEnd With
M. D.
Conc Mn ppmConc ppm BrConc N2On (wt.%)
10.0890.8710.035 7.40.664904506705.3
20.0700.8610.0647.20.5096089014206.2
30.0640.8970.0347.80.5097090014003.9
40.0820.8800.0348.10.665004707006.0
50.0890.8710.0357.40.6646043060 5.9
60.0830.8970.0347.80.4990084011905.1
70.0820.8800.0348.00.664704506405.5
80.0990.8320.06611.11.103403104908.1
90.0990.8320.06611.11.103303304507.8
100.0620.06810.60.663803605209.1
110.0940.8370.06611.11.043703605408.5
120.0620.8670.06810.60.663603404709.1
130.0610.8680.06710.70.653603405008.4
140.1450.7900.06211.71.70 3103104408.1
150.0920.8380.06611.01.014304105908.8
160.0880.8440.0637.30.6480076012206.9
170.0770.8540.0647.20.5587081013307.0
180.0660.8820.0489.70.644003706206.9
And0.2370.7040.05513.23.133203004507.3
In0.0990.8310.06611.11.104204005808.5

Table 1 (continued)
Gas flow rate (SCFH)Conc. oxygen in raw materials (vol.%)Liquid temperature (°F)Pressure (psi)Contact time (min)
11394.027722465
21394.0279224 105
31394.0285228102
41394.028822854
51394.028822455
61394.0287230105
71394.028922863
81394.029622640
91394.029622840
1039 4.0307230NA
111405.030923638
121394.0310228NA
131394.031922639
141426.032023838
151426.032023637
161415.030022085
171415.0320 232101
181415.032122647
And1415.031024034
In1394.031222439

Table 2
Analysis of exhaust gas from the first reactor
Example No.O2(mol. %)CO(mol. %)CO2(mol. %)The Us consumption (lb/Tyson PX)
11.290.0200.0612.1
21.040.0200.0632.0
31.040.0200.0642.1
40.990.0200.0892.8
51.120.0200.0602.1
60.980.0220.0722.3
71.070.0300.0772.7
81.180.0210.0942.9
91.050.0200.1013.0
101.050.0200.1003.2
111.260.0300.111 3.7
121.090.0200.1003.2
130.730.0300.1033.5
141.660.0310.1725.3
151.480.0310.1364.4
160.970.0360.1103.7
171.230.050Forms 0.1415.0
181.240.0400.1104.0
And0.020.1600.0605.4
In.04 0.1230.0504.3

Table 3
Analysis of the suspension from the first reactor
Example No.PX (ppm)NMVA (wt.%)TA (wt.%)SWA (wt.%)VA (wt.%)p-Tolarova acid (wt.%)p-Truelove aldehyde (wt.%)
179320.06302.55471.10900.00724.69281.1032
218900.035910.43271.12590.01311.99240.2860
316720.04509.81841.12590.0179 2.15450.2754
439230.04513.77721.09850.01154.03200.7933
562870.06143.58051.16470.01404.48130.9209
620450.038910.23781.03660.01641.98410.2431
753510.05383.58671.05600.01093.90520.8011
8204000.0717129500.76640.00625.81550.0437
9 202000.05901.06690.59700.00674.60451.7016
1012270.04223.63720.89800.01103.23520.5270
1197010.08912.78340.97990.01294.61901.0770
1227510.03983.31180.80410.01313.04320.6055
1329360.04313.78320.73520.01232.45050.4353
14251000.11232.2876 0.92830.02007.54481.9578
1541220.05796.21221.17690.02023.85550.6513
1611050.044315.20250.9820 is found0.02011.69250.1996
175610.01667.31530.1772Samples of 0.01130.25820.0296
1815340.02526.40180.65940.01551.74610.2452
And945000.11900.67530.47670.01117.1922 3.2307
In106000.08142.42101.02170.00874.85880.0242

341
Table 4
Conditions in the second reactor
Example No.Feed rate PX(lb/hour)The composition of the liquid in the reactor
The ratio of dissolved.(lb R-RIT./pound total submission PX in both reactors)Conc. Co (ppm)Conc. MP (ppm)Conc. VG (ppm)
12.42.86390360520
22.62.87400370560
32.63.01374520
42.42.98410380500
52.42.54370320470
62.63.06380360600
72,43.01380340450
82.02.58420410550
92.02.92350350460
102.43.24390360490
112.13.02400410540
122.43.07360340470
132.42.82390350510
141.43.06360350470
152.12.93460450590
162.52.79390370550
172.52.74390360580
182.5 2.49410400610
And0.02.68420400530
In2.02.35560540660

66
Table 4 (continued)
Conditions in the second reactor
Example No.Conc. H2O (wt.%)Liquid temperature (°F)Press. (psi)The rate of air flow (SCFH)Contact time (min)
110.938721316465
211.238721415863
312.638721815863
412.738721816162
511.538721416173
612.238622016061
712.738721815767
811.538821615972
912.138821915869
1012.7388 22016060
1112.738722716365
1212.438821816064
1311.638821615866
1412.138822815366
1512,638622616069
1611.438622216165
1711.7386222163
1811.538621616458
And12.038923015170
In11.238821415777

Table 5
Analysis of exhaust gas from the second reactor
Example No.O2(mol. %)WITH (mol. %)CO2(mol. %)The us consumption (lb/Tyson PX)
14.020.3461.19838.6
24.110.3691.09135.0
3 3.690.3541.26938.6
44.070.3891.30841.8
54.280.3361.18837.5
64.540.3301.13736.0
74.080.3251.19736.5
84.360.4181.38343.1
94.230.3681.27439.5
104.260.3821.43344.3
115.550.3941.404 45.5
124.090.3471.19837.7
134.150.3821.31340.4
146.000.3901.42043.3
156.000.4221.52048.2
165.420.3251.28840.3
175.250.3221.24239.2
184.760.3561.40544.5
And5.920.5181.68352.0
In4.30 0.5501.68852.9

Table 6
Analysis of the slurry from the second reactor
Example No.PX (ppm)NMVA (wt.%)SWA (wt.%)VA (wt.%)P-Toluyl. acid (wt.%)P-Toluyl. the aldehyde (wt.%)Conc. TA (wt.%)
14820.01150.30950.12180.53060.058537.1
23280.01180.28170.12290.39700.043837.6
34570.01530.34600.12530.56130.0614 33.9
43880.01500.28260.11420.46080.046536.3
54440.01180.32790.11620.53080.050737.5
63920.01270.29440.11570.46800.055435.1
75450.01310.34960.11310.61730.064633.9
84560.01020.23120.10880.40780.043736.7
9526 0.01140.27470.11160.54610.071035.3
104060.01790.27480.10940.43130.044135.0
114300.00900.22680.09170.37270.033833.3
125320.01740.34340.11880.58880.059934.9
133940.01450.26390.11180.43120.044737.1
145010.01060.24090.1126 0.43530.048233.4
152560.00860.20290.09220.25460.024733.2
162810.01330.23850.11090.34430.038436.6
173990.00760.13450,05660.20420.022737.5
184010.01050.27590.11110.37370.039941.4
And14490.01420.18890.09820.52500.134735.8
In3080.01000.20040.09830.26210.024238.1

Table 7
The analysis highlighted terephthalic acid
Example No.Complete consumption of Us ($2 react.) (lb/Tyson PX)The analysis highlighted terephthalic acid
BA (ppm)4-CBA (ppm)p-Toluyl. acid (ppm)NMVA (ppm)OD 340 Washed. and outfilter.
141613684619720.501
237543326353260.340
341 513993515640.399
444503050450400.536
540513569542640.509
638493768426490.290
7393942446171060.372
846442624365200.583
943353236 511460.563
1047313278446280.430
114942303251210.480
1241544272642360.450
1344373103345220.354
1449392552437210.470
1553272436248100.287
1644363006273150.247
1744363404335410.334
1848493528408540.402
And57542224499401.790
In57502223310211.083

Table 8
Comparative example No.1234 56789
The composition of raw materials (mass. share)
PX0.2530.2560.2550.2660.2550.2550.2560.2550.253
Us0.7120.7090.7100.7100.7100.7090.7100.7100.713
H2O0.0320.0320.0320.0320.0320.0320.032 0.0320.032
The speed of the fluid (lb/hour)10.610.610.510.58.710.58.710.68.7
The pace. (°F)387387387387386388386387387
Pressure (psi)220220219202207203204220215
The composition of the liquid in the reactor
The relationship will dissolve. (pound will dissolve. in the reactor/lb supplied PX2.662.792.752,632.482.742.692.722.78
With the liquid reactor (ppm)400440360380390340380400270
MP in the liquid reactor (ppm)380410320350380480320360240
VG in liquid reactor470520430450460600410470 340
H2O (wt.%).11.211.611.010.311.611.111.111.111.2
The rate of air flow (SCFH)162162158137122145125161124
Contact time (min)827775771297512280122

Table 9
Analysis of off-gas
Comparative example No.1234 56789
O2(mol.%)4.354.264.271.041.271.141.034.302.66
WITH (mol.%)0.3540.3950,3070.4800.6390.6420.5420.3480.395
CO2(MOL.%)1.2261.3141.0851.3301.7861.3341.5411.1571.366
Us consumption (lb/Tyson. PX)45.948.938.842.260.748.653.043,046.1

Table is CA 10
Analysis of the suspension from the reactor
Comparative example No.123456789
PX (ppm)3632855661224231518392334554
NMVA (wt.%) 0.0107Samples of 0.01130.00340.02970.00980.01780.01320.00940.0101
SWA (wt.%)0.2661051780.34750.62710.17970.36640.34000.23760.3035
VA (wt.%)0.13340.12720.14150.1519 0.13270.14290.16490.13000.1509
p-Tolarova acid (wt.%)0.43930.35940.66571.39910.26390.65020.62550.41280.5355
p-Truelove aldehyde (wt.%)0.04770.03970.07180.15990.03320.09820.0751 0.05400.0608
End-Oia terephthalic for you (wt.%)37.037.137.939.340.438.940.136.437.1

Table 11
The analysis highlighted terephthalic acid
Comparative example No.123456789
BA (ppm)585142746581835058
4-CBA (ppm).275124174057801622655131420026203461
p-Tolarova acid (ppm)4123966591563262665638390583
NMVA (ppm)29164320732142964044
Us consumption (lb/Tyson. PX) (repeated here for comparison with table 7)46 39426149534346
OD 340 washed and outfilter.0.3060.3300.3531.9181.0192.6771.2480.2920.528

From the above description it is seen that the objectives of the present invention have been achieved. Despite the fact that were are only some of the options, alternative embodiments and various modifications will be clear to experts from the above description. These and other alternatives are considered equivalent, if they do not contradict the spirit and scope of the present invention.

1. Continuous speed counter-current method of catalytic oxidation in a solvent at least one bin is Aulnay connection contains two replacement group, which is selected from the class consisting of alkyl, hydroxyalkyl, aldehyde, carboxylic groups and mixtures thereof, are able to oxidize to the corresponding acid derivative, comprising the following steps:
(a) introduction the first stage of oxylene mixture of raw materials containing at least a portion of the total amount of each of: (i) solvent, an organic acid, (ii) at least one catalytically active metal selected from manganese, cobalt, Nickel, zirconium, hafnium, cerium and mixtures thereof, and (iii) bromide in a molar ratio in the calculation of all catalytically active metals in the range of from 1:20 to 5:1 and 7 to 60 wt.% the total number of at least one disubstituted benzene introduced in stages (a) and (d);
(b) partial oxidation of at least one disubstituted benzene in the first stage of oxidation in the presence of a gas containing molecular oxygen originally in the amount of from 3 to 20 vol.%, at a temperature in the range from 121 to 205°C and relative amounts of disubstituted benzene, catalytic metal, solvent and bromine entered on step (a)to from 25 to 99.95 wt.% disubstituted benzene fed to the first stage of oxidation, oxidized to produce a gas mixture containing unreacted molecular to slort, evaporated the solvent and the first mixture of products containing the obtained acid derivative, partially oxidized disubstituted benzene, unreacted disubstituted benzene and the solvent, and at a pressure of from 8,96·10514.8·105PA sufficient to maintain the disubstituted benzene, partially oxidized disubstituted benzene, acid derivative and a solvent in a liquid state or in the form of a suspension of solids in a liquid so that the concentration of residual molecular oxygen remaining in the gas mixture ranges from 0.3 to 2 vol.%;
(c) the selection of the first product mixture after the first stage of oxidation and feeding at least part of the selected first mix of products in the second stage of oxidation;
(d) feeding the second stage oxidation gas containing molecular oxygen and the balance of the total amount of disubstituted benzene, catalytic metal, solvent and bromine;
(e) oxidation in the second stage of oxidation of the partially oxidized disubstituted benzene and unreacted disubstituted benzene fed to the second stage of oxidation, the gas containing molecular oxygen in an amount of from 15 to 50 vol.%, at a temperature in the range from 175 to 216°C and relative amounts of disubstituted benzene, partially oxidized disubstituted benzene, catalyti the definition of metal, solvent and bromine entered on step (a)to from 96 to 100 wt.% disubstituted benzene and partially oxidized disubstituted benzene was oxidized to produce a gas mixture containing unreacted molecular oxygen, the vaporized solvent and the second mixture of products containing the obtained acid derivative and a solvent, and at a pressure of from 11.7·105to 16.2·105PA in order to maintain the acid derivative, partially oxidized disubstituted benzene and unreacted disubstituted benzene mainly in the liquid state or in the form of a suspension of solids in a liquid so that the concentration of residual molecular oxygen remaining in the gas mixture will be from 3 to 15 vol.%;
(f) selection after the second stage of oxidation of the second mixture of products containing the obtained acid derivative; and
(g) selection after the second stage of oxidation and return to the first stage of the oxidation gas containing residual molecular oxygen.

2. The method according to claim 1, in which the disubstituted benzene is paradisaeidae benzene and the corresponding acid derivative is terephthalic acid.

3. The method according to claim 2, in which the substituents in the para-disubstituted benzene are alkyl groups containing from one to four carbon atoms.

4. The method according to claim 1, in Kotor is m the solvent is an acetic acid.

5. The method according to claim 1, in which the catalytically active metals are cobalt and manganese.

6. The method according to claim 5, in which the atomic ratio of manganese to cobalt in the reaction mixture in the first stage of oxidation is in the range from 1:100 to 100:1.

7. The method according to claim 1, in which the molar ratio of bromine to the amount of catalytically active metals in the reaction mixture of the first stage of oxidation is in the range from 1:5 to 2:1.

8. The method according to claim 1, in which the temperature in the first stage oxidation is supported in the interval from 136 to 177°C.

9. The method according to claim 1, wherein a gas containing molecular oxygen is introduced to the first stage of oxidation, contains from 3 to 11% vol. molecular oxygen.

10. The method according to claim 1, in which the residual concentration of molecular oxygen in the gas discharged after the first stage of oxidation, is 1%vol.

11. The method according to claim 1, in which the degree of conversion disubstituted benzene in a partially oxidized disubstituted benzene and acid derived in the first stage of oxidation ranges from 60 to 99.95 wt.%.

12. The method according to claim 1, wherein a gas containing molecular oxygen is supplied to the second stage of oxidation, contains from 20 to 25 vol.% molecular oxygen.

13. The method according to claim 1, in which the residual concentration of molecular oxygen in the gas taken after the second stage, okelani is, is from 3 to 11%vol.

14. The method according to item 13, in which the residual concentration of molecular oxygen in the gas taken after the second stage of oxidation, is from 3 to 8%vol.

15. The method according to claim 1, in which the degree of conversion disubstituted benzene and partially oxidized disubstituted benzene acid derivative in the second stage of oxidation ranges from 97 to 100 wt.%.

16. The method according to claim 6, in which from 20 to 100 wt.% total manganese introduced in stages (a) and (d)add at the first stage of oxidation.

17. The method according to claim 6, in which from 20 to 100 wt.% the total number of cobalt introduced in stages (a) and (d)add at the first stage of oxidation.

18. The method according to claim 1, in which from 20 to 100 wt.% the total number of bromine introduced in stages (a) and (d)add at the first stage of oxidation.

19. The method according to claim 1, in which from 15 to 35 wt.% the total number of disubstituted benzene introduced in stages (a) and (d)add at the first stage of oxidation.

20. The method according to claim 1 in which from 10 to 100 wt.% the total quantity of solvent introduced at stages (a) and (d)add at the first stage of oxidation.

21. The method according to claim 1, in which the temperature in the first stage of oxidation is at least 5.5°C lower than the temperature in the second stage of oxidation.

22. The method according to claim 1, in which the gas is removed after the first stage of oxidation, partially Conde is serout for to remove condensation from the solvent, and at least part of the condensed solvent is injected at the first stage of oxidation in the second stage of oxidation, or both stages of the process.

23. The method according to item 22, in which at least part of the condensed solvent is injected at the first stage of oxidation.

24. The method according to item 22, in which at least part of the condensed solvent is injected in the second stage of oxidation.

25. The method according to item 22, in which essentially all of the condensed solvent is injected in the second stage of oxidation.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method for oxidising of aromatic hydrocarbon such as para-xylol, meta-xylol, 2,6-dimethylnaphthalene or pseudocumene with forming of corresponding organic acid. The oxidation is implemented by the source of molecular oxygen in liquid phase at temperature range from 50°C to 250°C in the presence of catalyst being a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon. The invention refers also to the catalytic system for obtaining of organic acid by the liquid-phase oxidation of aromatic hydrocarbons representing: a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon.

EFFECT: activation of the aromatic hydrocarbons oxidation increasing the yield of target products and allowing to decrease the catalyst concentration and the temperature of the process.

45 cl, 4 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: method of obtaining product - purified carboxylic acid, includes: (a) oxidation of aromatic initial materials in primary oxidation zone with formation of raw carboxylic acid suspension; where raw carboxylic acid suspension contains terephthalic acid; where said oxidation is carried out at temperature within the range from 120°C to 200°C; (b) withdrawal of admixtures from raw suspension of carboxylic acid, removed at temperature from 140°C to 170°C from stage of oxidation of paraxylol in primary oxidation zone and containing terephthalic acid, catalyst, acetic acid and admixtures, realised in zone of solid products and liquid separation with formation of mother liquid flow and product in form of suspension; where part of said catalyst in said suspension of raw carboxylic acid is removed in said mother liquid flow; and where into said zone of solid products and liquid separation optionally additional solvent is added; (c) oxidation of said product in form of suspension in zone of further oxidation with formation of product of further oxidation; where said oxidation is carried out at temperature within the range from 190°C to 280°C; and where said oxidation takes place in said zone of further oxidation at temperature higher than in said primary oxidation zone; (d) crystallisation of said product of further oxidation in crystallisation zone with formation of crystallised product in form of suspension; (e) cooling of said crystallised product in form of suspension in cooling zone with formation of cooled suspension of purified carboxylic acid; and (i) filtration and optionally drying of said cooled suspension of purified carboxylic acid in filtration and drying zone in order to remove part of solvent from said cooled suspension of carboxylic acid with obtaining of said product - purified carboxylic acid.

EFFECT: purified carboxylic acid with nice colour and low level of admixtures, without using stages of purification like hydration.

8 cl, 1 tbl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention pertains to improved method of lowering content of 4-carboxybenzoldehyde and p-toluic acid in benzenedicarboxylic acid, which is terephtalic acid. Method involves: (1) supplying (i) p-xylene (ii) water acetic acid reaction medium, containing oxidation catalyst, containing source of cobalt, manganese and bromine source, dissolved in it, and (iii) acid containing gas in the first oxidation zone at high pressure, in which there is liquid phase, exothermal oxidation of p-xylene. In the first reactor, oxidation at high temperature and pressure is maintained at 150-165°C and 3.5-13 bars respectively; (2) removal from the upper part of the first reactor of vapour, containing water vapour, acetic acid reaction medium and oxygen depleted gas, and directing the vapour into the column for removing water; (3) removal from the lower part of the column for removing water of liquid, containing partially dehydrated acetic acid solution; (4) removal from the lower part of the first reactor of the oxidation product, containing (i) solid and dissolved terephtalic acid, 4-carboxybenzaldehyde and p-toluic acid, (ii) water acetic acid reaction medium, containing oxidation catalyst dissolved in it; (5) supplying (i) product of oxidation from stage (4), (ii) oxygen containing gas and (iii) solvent in vapour form, containing acetic acid, obtained from a portion of partially dehydrated acetic acid solvent from stage (3) into the second oxidation zone high pressure, in which there is liquid phase exothermal oxidation of 4-carboxybenzaldehyde and p-toluic acid, where temperature and pressure in the second reactor of oxidation at high pressure is maintained at 185-230°C and 4.5-18.3 bars respectively; (6) removal from the upper part of the second reactor of vapour, containing water vapour, acetic acid reaction medium, and oxygen depleted gas; (7) removal from the lower part of the second reactor of the product of second oxidation, containing (i) solid and dissolved terephtalic acid and (ii) water acetic acid reaction medium; and (8) separation of terephtalic acid from (ii) water acetic acid reaction medium from stage (7) with obtaining of terephtalic acid. The invention also relates to methods of obtaining terephtalic acid (versions). The obtained product is terephtalic acid, with an overall concentration of 4-carboxybenzaldehyde and p-toluic acid of 150 ppm or less.

EFFECT: improved method of lowering content of 4-carboxybenzoldehyde and p-toluic acid in benzenedicarboxylic acid and obtaining terephtalic acid.

13 cl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method, by which the carboxylic acid/diol mixture, that is suitable as the initial substance for the manufacture of polyester, obtained from the decolourised solution of carboxylic acid without actually isolating the solid dry carboxylic acid. More specifically, the invention relates to the method of manufacturing a mixture of carboxylic acid/diol, where the said method includes the addition of diol to the decolourised solution of carboxylic acid, which includes carboxylic acid and water, in the zone of the reactor etherification, where diol is located at a temperature sufficient for evaporating part of the water in order to become the basic suspending liquid with the formation of the specified carboxylic acid/diol mixture; where the said carboxylic acid and diol enter into a reaction in the zone of etherification with the formation of a flow of a complex hydroxyalkyl ether. The invention also relates to the following variants of the method: the method of manufacture of the carboxylic acid/diol mixture, where the said method includes the following stages: (a) mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of damp carboxylic acid; where the said carboxylic acid is selected from the group, which includes terephthalic acid, isophthatic acid, naphthalenedicarboxylic acid and their mixtures; (b) discolourisation of aforesaid solution of damp carboxylic acid in the zone for reaction obtaining the decolourised solution of carboxylic acid; (c) not necessarily, instantaneous evaporation of the said decolourised solution of carboxylic acid in the zone of instantaneous evaporation for the removal of part of the water from the decolourised solution of carboxylic acid; and (d) addition of diol to the decolourised solution of carboxylic acid in the zone of the reactor of the etherification, where the said diol is located at a temperature, sufficient for the evaporation of part of the water in order to become the basic suspending liquid with the formation of the carboxylic acid/diol mixture; where the aforesaid carboxylic acid and diol then enter the zone of etherification with the formation of the flow of complex hydroxyalkyl ether; and relates to the method of manufacture of carboxylic acid/diol, where the said method includes the following stages: (a) the mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of carboxylic acid; (b) discolourisation of the said solution of damp carboxylic acid in the reactor core with the formation of the decolourised solution of carboxylic acid; (c) crystallisation of the said decolourised solution of carboxylic acid in the zone of crystallisation with the formation of an aqueous suspension; and (d) removal of part of the contaminated water in the aforesaid aqueous solution and addition of diol into the zone of the removal of liquid with the obtaining of the said carboxylic acid/diol mixture, where diol is located at a temperature sufficient for evaporating part of the contaminated water from the said aqueous suspension in order to become the basic suspending liquid.

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: chemistry.

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

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

19 cl, 1 dwg, 6 ex, 4 tbl

FIELD: carbon materials and hydrogenation-dehydrogenation catalysts.

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

EFFECT: increased mechanical strength and abrasion resistance.

8 cl, 4 ex

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

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

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

8 cl, 3 tbl, 2 dwg, 3 ex

FIELD: organic chemistry, chemical technology.

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

EFFECT: improved method of crystallization.

3 cl, 1 dwg, 1 tbl, 2 ex

FIELD: organic chemistry, chemical technology.

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

EFFECT: improved treatment method.

5 cl, 1 ex

FIELD: organic chemistry, chemical technology.

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

EFFECT: improved method for preparing.

1 tbl, 1 dwg, 14 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing basic phthalate of iron (III), which is used in chemical practice, analytical control and scientific research, through direct reaction of iron with atmospheric oxygen and phthalic acid in the presence of organic solvent, where the stimulating additive used is hydrochloric acid and inorganic chlorides in amount ranging from 0.013 to 0.062 mol/kg of the load. The liquid phase solvent is n-butyl alcohol iron which is crushed and moved in the reaction zone in form of steel balls with diametre ranging from 2.2 to 3.7 mm, alone or in combination with crushed cast iron in any mass ratio. Initial content of phthalic acid is varied from 1.0 to 1.5 mol/kg of the load. The reactor used is a vertical type bead mill with the grinding agent in form of steel balls and crushed alloy of iron together with glass beads in mass ratio of iron-containing reagent, beads and the rest of the load equal to 1:1:0.6 with a spill pipe as a bubbler during the process. Loading is done in the following sequence: grinding agent and moved metal, liquid phase solvent, phthalic acid, chlorine-containing stimulating agent, and the process itself starts with heating contents of the reactor to 35°, is carried out with self-heating in the range 35 to 50°C while stirring continuously, bubbling air at a rate of 2.3 to 3.1 l/(min kg of load), while maintaining temperature using a cooling liquid bath and controlling the process using a sampling method until exhaustion of all loaded acid, after which bubbling is stopped. Suspension of the reaction mixture is let to flow under gravity through a net lying in the field of a permanent magnet into the receiving tank of a vacuum filter, after which it is filtered. The residue is washed with the liquid phase solvent and taken for purification, and the primary filtrate and washing solvent are returned to the repeated process.

EFFECT: non-waste method at low temperature; wastes from other industries can be used as reagents; desired products can be separated by simple filtration.

2 cl, 8 ex

FIELD: chemistry.

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

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

2 ex

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method for oxidising of aromatic hydrocarbon such as para-xylol, meta-xylol, 2,6-dimethylnaphthalene or pseudocumene with forming of corresponding organic acid. The oxidation is implemented by the source of molecular oxygen in liquid phase at temperature range from 50°C to 250°C in the presence of catalyst being a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon. The invention refers also to the catalytic system for obtaining of organic acid by the liquid-phase oxidation of aromatic hydrocarbons representing: a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon.

EFFECT: activation of the aromatic hydrocarbons oxidation increasing the yield of target products and allowing to decrease the catalyst concentration and the temperature of the process.

45 cl, 4 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method for oxidising of aromatic hydrocarbon such as para-xylol, meta-xylol, 2,6-dimethylnaphthalene or pseudocumene with forming of corresponding organic acid. The oxidation is implemented by the source of molecular oxygen in liquid phase at temperature range from 50°C to 250°C in the presence of catalyst being a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon. The invention refers also to the catalytic system for obtaining of organic acid by the liquid-phase oxidation of aromatic hydrocarbons representing: a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon.

EFFECT: activation of the aromatic hydrocarbons oxidation increasing the yield of target products and allowing to decrease the catalyst concentration and the temperature of the process.

45 cl, 4 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method for oxidising of aromatic hydrocarbon such as para-xylol, meta-xylol, 2,6-dimethylnaphthalene or pseudocumene with forming of corresponding organic acid. The oxidation is implemented by the source of molecular oxygen in liquid phase at temperature range from 50°C to 250°C in the presence of catalyst being a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon. The invention refers also to the catalytic system for obtaining of organic acid by the liquid-phase oxidation of aromatic hydrocarbons representing: a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon.

EFFECT: activation of the aromatic hydrocarbons oxidation increasing the yield of target products and allowing to decrease the catalyst concentration and the temperature of the process.

45 cl, 4 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method for oxidising of aromatic hydrocarbon such as para-xylol, meta-xylol, 2,6-dimethylnaphthalene or pseudocumene with forming of corresponding organic acid. The oxidation is implemented by the source of molecular oxygen in liquid phase at temperature range from 50°C to 250°C in the presence of catalyst being a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon. The invention refers also to the catalytic system for obtaining of organic acid by the liquid-phase oxidation of aromatic hydrocarbons representing: a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon.

EFFECT: activation of the aromatic hydrocarbons oxidation increasing the yield of target products and allowing to decrease the catalyst concentration and the temperature of the process.

45 cl, 4 tbl, 16 ex

FIELD: chemistry, pharmacology.

SUBSTANCE: present invention relates to new use of compounds of 2-arylacetic acid and amides with formula (I) and their pharmaceutically used salts, where A comprises an atom X and is phenyl or a 5-6 member heteroaromatic ring, optionally containing a heteroatom, chosen from N; corresponding positions on ring A are marked by numbers 1 and 2; atom X is chosen from N (nitrogen) and C (carbon); R represents a substituting group on ring A, chosen from: a group in 3 (meta) positions, chosen from a group comprising straight or branched C1-C5-alkyl, C2-C5-acyl; a group in 4 (para) positions, chosen from a group, comprising C1-C5-alkyl, C1-C5-alkanesulphonylamino, substituted with halogens; Hy represents a small hydrophobic group with steric inhibition constant ν between 0.5 and 0.9 (where ν is Charton steric constant for substitutes), comprising methyl, ethyl, chlorine, bromine, group Y chosen from O (oxygen) and NH; when Y represents O (oxygen), R' represents H (hydrogen); when Y represents NH, R' is chosen from groups: -H, - residue with formula SO2Rd, where Rd represents C1-C6-alkyl. The invention can be used in making medicinal agents, which are inhibitors of induced IL-8 PMN chemotaxis (CXCR1) or induced GRO-α PMN chemotaxis (CXCR2).

EFFECT: new use of compounds of 2-arylacetic acid and amides and their pharmaceutically used salts.

14 cl, 2 tbl, 44 ex, 4 dwg

FIELD: chemistry.

SUBSTANCE: present invention pertains to new compounds with general formula (I), in which X1 is phenyl, 9-member bicyclic heteroaryl, containing S or O as heteroatoms, or 5-member heteroaryl, containing S or O as heteroatoms, each of which is optionally substituted with one or more substitutes, chosen from halogen or C1-6alkyl, which is optionally substituted with one or more halogens. X2 is phenyl, which is optionally substituted with one or more substitutes, chosen from halogen, or 5-member heteroaryl, containing S or O as heteroatoms. Ar is phenylene, which is optionally substituted with one or more substitutes, chosen from halogen, or C1-6alkyl, phenyl, C1-6alkoxy, each of which is optionally substituted with one or more halogens. Y1 is O or S, and Y2 represents O, Z represents -(CH2)n-, where n equals 1, 2 or 3. R1 is hydrogen or C1-6alkoxy and R2 is hydrogen, C1-6alkyl. The invention also relates to pharmaceutical salts of these compounds or any of their tautomeric forms, stereoisomers, stereoisomer mixtures, including racemic mixtures.

EFFECT: invention also pertains to use of these compounds as pharmaceutical compositions, with effect on receptors, activated by the peroxisome proliferator PPARδ subtype, and to pharmaceutical compositions, containing these compounds (I).

36 cl, 41 ex

FIELD: chemistry.

SUBSTANCE: claimed method of obtaining alkylaromatic monocarboxylic acids involves liquid phase oxidation of dialkyl-substituted aromatic hydrocarbons by oxygen-containing gas in the presence of catalyst at high temperature. Alkyltrimethylammonium bromide with alkyl C14-C16 or their mix at 0.3-0.5 wt % of hydrocarbon weight is used as catalyst. Process is performed at 90-120°C until mass ratio of alkylaromatic acid to alkylaromatic aldehyde in the mix reaches 1:1.3-3.0, then alkylaromatic acid is separated, and unreacted hydrocarbon and aldehyde are returned to the process.

EFFECT: possibility to perform mild partial oxidation of dialkyl-substituted aromatic hydrocarbons selectively by one alkyl group without adding transition metals.

2 cl, 8 ex

FIELD: chemistry.

SUBSTANCE: claimed method of obtaining alkylaromatic monocarboxylic acids involves liquid phase oxidation of dialkyl-substituted aromatic hydrocarbons by oxygen-containing gas in the presence of catalyst at high temperature. Alkyltrimethylammonium bromide with alkyl C14-C16 or their mix at 0.3-0.5 wt % of hydrocarbon weight is used as catalyst. Process is performed at 90-120°C until mass ratio of alkylaromatic acid to alkylaromatic aldehyde in the mix reaches 1:1.3-3.0, then alkylaromatic acid is separated, and unreacted hydrocarbon and aldehyde are returned to the process.

EFFECT: possibility to perform mild partial oxidation of dialkyl-substituted aromatic hydrocarbons selectively by one alkyl group without adding transition metals.

2 cl, 8 ex

FIELD: chemistry.

SUBSTANCE: present invention relates to a catalyst for producing phthalic acid anhydride by gas phase oxidation of o-xylol and/or naphthalene, with the said catalyst containing at least three catalyst layers with different compositions, which are designated in order, starting from the gas inlet side to the gas outlet side, as the first, second and third catalyst layers. Said catalyst layers respectively contain an active material containing TiO2 with Na content less than 0.3 wt %, and the active material content reduces from the first catalyst layer facing the gas inlet side to the third catalyst layer facing the gas outlet side, with the proviso that (a) the first catalyst layer comprises an active material content of between approximately 7 and 12 wt %, (b) the second catalyst layer comprises an active material content ranging between 6 and 11 wt %, the active material content of the second catalyst layer being less than or equal to the active material content of the first catalyst layer and (c) the third catalyst layer comprises an active material content ranging between 5 and 10 wt %, the active material content of the third catalyst layer being less than or equal to the active material content of the second catalyst layer. A method is described fro producing phthalic acid anhydride by gas phase oxidation of o-xylol and/or naphthalene using the catalyst described above.

EFFECT: high output of phthalic acid anhydride.

34 cl, 3 tbl, 13 ex

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