Catalyst for oxidization of the vanadium oxide particles in the gaseous phase with the certain size distribution

FIELD: chemical industry; non-ferrous metallurgy industry; other industries; methods of production of the catalyst for oxidization of the vanadium oxide particles in the gaseous phase with the definite size distribution.

SUBSTANCE: the invention is pertaining to the method of production of the catalyst for oxidization in the gaseous phase of the vanadium oxide particles with the definite size distribution. The invention describes the method of production of the catalyst for oxidization in the gaseous phase, at which on the fluidized inert carrier they deposit the suspension of TiO2 and V2O5 particles, in which, at least, 90 volumetric % of the particles of V2O5 have the diameter of 20 microns or less and, at least, 95 volumetric % of the particles of V2O5 have the diameter of 30 microns or less. The technical result of the invention is that the certain particle-size distribution allows to achieve the high efficiency of the coating.

EFFECT: the invention allows to achieve the high efficiency of the coating.

6 cl, 2 ex

 

The invention relates to incorporating particles of titanium dioxide and vanadium oxide catalyst for oxidation in the gas phase with a certain size distribution of particles of vanadium oxide, the method of its production, as well as the application of a catalyst to obtain the anhydride of phthalic acid from o-xylene, naphthalene or mixtures thereof.

Many carboxylic acids and/or anhydrides of carboxylic acids technically get by catalytic oxidation in the gas phase aromatic hydrocarbons such as benzene, xylenes, naphthalene, toluene or durene, in reactors with a fixed layer. Thus can be obtained, for example, benzoic acid, maleic acid anhydride, phthalic anhydride, isophthalic acid, terephthalic acid or the anhydride pyromellitates acid. In General a mixture of oxygen-containing gas and subject to oxidation source material is passed through a pipe in which there is a filling of at least one catalyst. To control the temperature of the pipe surrounded by the heat medium, for example a salt melt.

As a catalyst for such oxidation reactions are suitable so-called shell catalysts in which the catalytically active mass deposited in the form of a coating on an inert carrier, such as steatite. As a catalytically active component of the catalytically active mass of these shell catalysts is in General along with titanium dioxide, a vanadium pentoxide. Later in the catalytically active mass may contain small amounts of many other oxidic compounds which as promoters affect the activity and selectivity of the catalyst.

To obtain such shell catalysts in aqueous suspension, the components of the active mass and/or their compounds, the precursors of napraschivaet on the carrier material at a high temperature to achieve the desired proportion of active weight of the total weight of the catalyst.

The document DE-a 2550686 describes the way in which the media is applied an aqueous solution containing titanium tetrachloride and the salt of vanadium(IV).

When described in DE-A 1442590 method of obtaining the solution vandelannoite, formamide and water serving of micronized titanium dioxide in the modification of anatase. The resulting suspension is applied on an inert catalyst carrier.

Document WO 00/12214 describes the method of obtaining, in which a mixture of titanium dioxide, vandelannoite, organic binder and, if necessary, promoters put the Foundation in a pelleting drum, applying a layer in the fluidized bed or powder coated in the form of a shell in two concentric layer on an inert carrier.

The document EP-A 539878 offers catalysts anhydride and phthalic acid in the gas phase. The ammonium metavanadate is dissolved in p is the target of oxalic acid and stirred together with promoters. Then carry out a Supplement TiO2obtained from the sulfate , titanium sulfate method of cooking. The resulting suspension is homogenized at a high temperature napraschivaet on the catalyst carrier.

According to DE-A 2106796 and DE-A 19633757 on the media cause suspension of anatase and dioxide based hydrate, V2About5and organic binder component.

Known methods for producing relative to the applied sources of vanadium can be divided into two classes: in the first case, as the source of vanadium using soluble compound of vanadium(IV), such as androcell. The recovery of vanadium (IV) occurs with organic restorative agent, such as oxalic acid. In another case, the aqueous slurry type insoluble compound of vanadium (V), such as V2O5because here there is no requirement restorative agent, the cost of the original substance is small. The disadvantage however is that the particles V2O5when the coating process in the fluidized bed is prone to emulgirovaniu and not completely fall to be covering media, and partially allocated, for example, with the air of a process or as a layer deposited on the apparatus for the coating. For loss compensation should be applied in excess of V2O5. Gellately what about the surplus to keep as minimal as possible.

The basis of the invention is the development of cost-effective method of obtaining containing titanium dioxide and vanadium oxide catalysts for oxidation in the gas phase and obtained this way catalysts.

According to the invention it was found that the effectiveness of the coatings depends strongly on the size distribution of particles V2O5suspended in the slurry for coating.

The invention relates to a catalyst for oxidation in the gas phase, which comprises an inert carrier and applied catalytically active mass, which contains from 1 to 40 wt.% of vanadium oxide, calculated as V2O5and from 60 to 99 wt.% of titanium dioxide, calculated as TiO2and is obtained by applying a suspension of particles of TiO2and V2O5on the carrier, and the suspension of at least 90 vol.% particle V2O5has a diameter of 20 μm or less and at least 95 vol.% particle V2O5has a diameter of 30 μm or less.

In addition, the invention relates to a method for producing a catalyst for oxidation in the gas phase, in which a fluidized bed of inert carrier cause suspension of particles V2O5and V2O5in which at least 90 vol.% particle V2O5has a diameter of 20 μm or less and at least 95 vol.% particle V2O5has the diameter is 30 μm or less.

Preferably, at least 90 vol.% particle V2O5has a diameter of 15 μm or less and at least 95 vol.% particle V2O5has a diameter of 20 μm or less.

According to a special form of execution of at least 60 vol.% particle V2O5has a diameter of 4 μm or at least 80% vol. particle V2O5has a diameter of 10 microns or less, at least 90 vol.% particle V2O5has a diameter of 15 μm or less and at least 95 vol.% particle V2O5has a diameter of 20 μm or less.

Preferably, at least 50 vol.% particle V2O5has a diameter of more than 2 μm. Recalculated on the amount of the value of D50is, preferably, from 2.0 to 2.5 μm.

Recalculated on the volume distribution of particle sizes is determined appropriate for the purposes of the invention by means of laser diffraction and evaluation method of Fraunhofer. In this method, parallel directional laser light is subjected to diffraction by particles. Each particle produces a characteristic for its size diraction pattern. Range of diffraction is registered by the detectors and is calculated by microcomputer distribution of particle size as a three-dimensional distribution.

Suitable for vanadium dioxide distribution of particle sizes can be obtained sufficient length is entrusted by grinding in a suitable mill. For example, suitable reflective mill, roller mill, vibrating mill, mill with grinding bodies (grinder) or tilted mill. Mills with grinding bodies preferred. They consist of a horizontal cylindrical working chamber, rotating around the hard point of rotation. The working chamber is filled with grinding bodies, usually of different sizes. Pomology material is the volume of voids with grinding phone as grinding bodies used durable for wear forged or cast steel balls, rods, respectively, the segments of the rods. Depending on the number of revolutions of the mill established various forms of movement of the grinding bodies and these different kinds of loads of material for grinding, such as friction, stress, blasting and pressure, resulting in the break up larger particles of the material for grinding.

Preferably the catalytically active mass contains caliciviruses condition, in terms of the total number of catalytically active mass, from 1 to 40 wt.% of vanadium oxide, calculated as V2O5and from 60 to 99 wt.% of titanium dioxide, calculated as TiO2along with this, the catalytically active mass may contain up to 1 wt.% compounds of cesium, calculated as Cs, up to 1 wt.% connect the deposits of phosphorus, calculated as P, and up to 10 wt.% oxide of antimony, calculated as Sb2O3.

Along with optional additives cesium and phosphorus in the catalytically active mass, in principle, can contain small amounts of many other oxidic compounds which as promoters affect the activity and selectivity of the catalyst, for example, they increase or decrease its activity. As such promoters should be called, for example, oxides of alkali metals, in particular, in addition to the aforementioned oxide cesium, lithium oxide, potassium and rubidium oxide) waist(I), aluminum oxide, zirconium oxide, iron oxide, Nickel oxide, cobalt oxide, manganese oxide, tin oxide, silver oxide, copper oxide, chromium oxide, molybdenum oxide, tungsten oxide, iridium oxide, tantalum oxide, niobium oxide, arsenic oxide, antimony oxide, cerium oxide. As a rule, this group used cesium as a promoter.

Next, from the promoters are preferred as additives oxides of niobium and tungsten in amounts of from 0.01 to 0.50 wt.%, in terms of the catalytically active mass. As increasing activity, but reduces the selectivity of additives suitable mainly of an oxide of phosphorus compounds, in particular phosphorus pentoxide.

Used titanium dioxide consists, preferably, of a mixture TO 2with the surface on BET from 5 to 15 m2/g and TiO2with the surface on BET from 5 to 15 m2/, you Can also apply only titanium dioxide with a BET surface of from 5 to 50 m2/g, preferably from 13 to 28 m2/year

As inert material carrier can be used in nearly all media materials known from the prior art, to obtain shell catalysts for the oxidation of aromatic hydrocarbons to aldehydes, carboxylic acids and/or anhydrides of carboxylic acids, for example quartz (SiO2), porcelain, magnesium oxide, tin dioxide, silicon carbide, rutile, clay (Al2About3), aluminum silicate, steatite (magnesium silicate), zirconium silicate, silicate of cerium or mixtures of these materials. Typically, the material of the porous media. The expression "non-porous" it should be understood as "to technically inefficient in the number of long non-porous", as technically a small number of pores in the material of the carrier may have, in the ideal case, the material does not contain pores. As the preferred material of the carrier should be allocated steatite and silicon carbide. The shape of the material media in General is not important for catalizer-predshestvennika according to the invention and for shell catalyst. For example, carriers of the catalyst can be in the form of beads, rings, tablets, JV is Raleigh, tubes, extrudates or gravel. The sizes of these catalyst carriers correspond to the sizes typically used to obtain shell catalysts for partial oxidation in the gas phase aromatic hydrocarbons. Preferably steatite is used in the form of beads with a diameter from 3 to 6 or rings with an external diameter of from 5 to 9 mm and a length of from 3 to 8 mm and wall thickness from 1 to 2 mm.

With the method according to the invention the coating layer(s) shell catalyst is carried out by the Foundation suspensions of TiO2and V2O5that, if necessary, contains the sources of the above-mentioned promoter elements in fluid media. Before coating, the suspension is plenty long mix, for example from 2 to 30 hours, in particular from 12 to 25 hours to break up the agglomerates suspended solids and to obtain a homogeneous suspension. The suspension typically has a solids content of 20 to 50 wt.%. Suspension the environment in General, water in nature, such as water itself or a water mixture mixed with water, an organic solvent, such as methanol, ethanol, isopropanol, formamide etc.

As a rule, to the suspension are added organic binders, preferably copolymers, preferably in the form of aqueous dispersions, vinyl acetate and of vanillaware, vinyl acetate and acrylate, starla and acrylate, and vinyl acetate and ethylene. Binders are commercially available as aqueous dispersions have a solids content, for example, from 35 to 65 wt.%. Used the number of such dispersions of the binder is in General from 2 to 45 wt.%, preferably from 5 to 35 wt.%, especially preferably from 7 to 20 wt.%, in terms of the weight of the suspension.

The media is subjected to pseudomedicine in device fluidized bed, respectively, fluidized bed in an upward gas flow, in particular air. The device consist in most cases of conical or ball capacity, in which pseudoviruses gas is introduced from the bottom up through the immersion pipe. The suspension is injected through the nozzle top, side or bottom of the fluidized bed. Preferably the application located in the middle, respectively, concentrically located around the dip tube of the rising pipe. Within the rising pipe reigns increased speed, which is transported particles up. In the outer ring of the velocity of the gas is only slightly higher than the rate of loosening. Thus the particles move vertically koltseobrazno. A suitable device fluidized bed is described, for example, in DE-A 4006935.

When the coating of the carrier of the catalyst is catalytically active mass in General note shall alter the temperature from 20 to 500° C, and the coating can be carried out at atmospheric pressure or under reduced pressure. In General, the coating is carried out at 0°to 200°C, preferably at 20 to 150°With, in particular from 60 to 120°C.

The catalytically active mass can be applied in two or more layers, with the inner layer or inner layers may have the content of the oxide of antimony up to 15 wt.% and the outer layer can be reduced by 50 to 100% of the content of the oxide of antimony. In this case, as a rule, the inner layer catalyst contains phosphorus and the outer layer is poor in phosphorus or does not contain phosphorus.

The thickness of the catalytically active mass is usually from 0.02 to 0.2 mm, preferably from 0.05 to 0.15 mm, the share of the active mass of the catalyst is usually from 5 to 25 wt.%, in most cases ranging from 7 to 15 wt.%.

Through heat treatment of the thus obtained catalyst-precursor at temperatures from more than 200 to 500°binder evaporates from the applied layer by thermal decomposition and/or combustion. Preferably the heat treatment is carried out in situ in the oxidation reactor in the gas phase.

The catalysts according to the invention are suitable for gas-phase oxidation of aromatic hydrocarbons with the number of carbon atoms from 6 to 10, such as benzene, xylenes, toluene,naphthalene or durene (1, 2, 4, 5-tetramethylbenzene) in carboxylic acids and/or anhydrides of carboxylic acids, such as maleic acid anhydride, phthalic anhydride, benzoic acid and/or anhydride pyromellitates acid.

For this purpose, obtained according to the invention the catalyst is filled in a heated outside on the reaction temperature, for example, by means of a salt melt of the reaction tube and above the thus obtained catalyst layer pass of the reaction gas with temperature is in General from 300 to 450°C, preferably from 320 to 420°and especially preferably from 340 to 400°and when excessive pressure is in General from 0.1 to 2.5 bar, preferably from 0.3 to 1.5 bar with a bulk velocity in General from 750 to 5000 hours

Submitted to the catalyst, the reaction gas produced in the total mixture containing molecular oxygen gas, which in addition to oxygen may also contain suitable reaction retarders and/or diluents such as steam, carbon dioxide and/or nitrogen, with the subject oxidation of aromatic hydrocarbons, and containing molecular oxygen gas in General may contain from 1 to 100 mol.%, preferably from 2 to 50 mol.% and particularly preferably from 10 to 30 mol.%, oxygen, from 0 to 30 mol.%, preferably from 0 to 10 mol.%, hydrogen and from 0 to 50 mol.%, preferably from 0 to 1 mol. %carbon dioxide, balance and who from. To obtain reaction gas containing molecular oxygen gas in the total serving of 30 g to 150 g per nm3gas to be oxidation of aromatic hydrocarbons.

Especially preferred was such an implementation, in which the catalyst layer is applied catalysts that differ in their catalytic activity and/or chemical composition of the active mass. Preferably when using two catalyst zones in the first zone, i.e. lying on the side of the entrance reaktsionnogo gas reaction zone, use the catalyst as compared with the catalyst, which is in the second, lying on the output side of the reaction gas reaction, the area has a slightly lower catalytic activity. In General the reaction interactions control the temperature setting so that the first area becomes a large part contained in the reaction gas aromatic hydrocarbon at maximum output. Preferably used from three - to five-layer catalyst system, in particular the three - and four-layer catalyst system.

The invention is explained in more detail by the following examples.

Measuring the distribution of particle size is carried out using apparatus Frisch Particle Sizer "analysette 22" measuring range from 0.3 to 300 microns with usausa capacity 62 channels. Sample V2O5for measuring suspended in water and pumped into the measuring cell. The duration of the measurement is 2 Scans (scan cycle), the assessment is made by the method of Fraunhofer.

Example 1

54,227 kg of anatase (BET surface 9 m2/g), 126,517 kg of anatase (BET surface of 20 m2/g), 14,195 kg V2O5, 3,549 kg Sb2O3, 0,805 kg of cesium carbonate are suspended in 519,035 kg of deionized water and stirred to obtain a homogeneous distribution. V2O5has the following recalculated on the volume distribution of particle size: 10%≤of 0.58 μm; 20%≤of 0.87 μm; 30%≤of 1.20 μm; 40%≤to 1.61 μm; 50%≤of 2.21 μm; 60%≤3,26 μm; 70%≤5,52 μm; 80%≤9,46 μm; 90%≤14,92 μm; 95%≤19,51 microns; 99,9%≤169,33 μm. To a suspension add 80 kg organic binder consisting of a copolymer of vinyl acetate and vanillaware in the form of a 50 wt.%-Noah dispersion. In the device coating fluidized bed 60 kg of this suspension napraschivaet 150 kg staticobj rings (magnesium silicate) with dimensions of 7×7×4 mm (external diameter × height × inner diameter) and dried. The coating is carried out at a temperature of 80-120°and the amount of air 6000 m3/PM

Analysis calcinatory at 400°catalysts showed that the proportion of V2O5in the active mass is 6,85 wt.%. RAS is cityvalue specified fraction V 2O5calcined active mass is in contrast 7,12 wt.%. There is a deficient amount of 0.27% (absolute). To compensate for the loss of V2O5in the coating and obtain a catalyst with a specified number V2O5it was necessary to increase the number of V2O5in suspension 0,543 kg

Comparative example 2

Example 1 is repeated, with the applied V2O5has the following recalculated on the volume distribution of particle size: 10%≤of 0.62 μm; 20%≤0,93 microns; 30%≤1,25 μm; 40%≤and 1.63 μm; 50%≤2,10 μm; 60%≤was 2.76 μm; 70%≤3,84 μm; 80%≤6,27 μm; 90%≤24,24 μm; 95%≤46,58 microns; 99,9%≤300 μm.

Analysis calcinatory at 400°catalysts showed that the proportion of V2O5in the active mass is of 5.55 wt.%. With respect to the set value in 7,12 wt.% is the missing number of 1.57% (absolute). To compensate for the loss of V2O5in the coating and obtain a catalyst with a specified number V2O5it was necessary to increase the number of V2O5in suspension 3,134 kg

The above examples show that the use of V2O5with a certain distribution of particle size can reduce the required applied number.

1. A method of producing a catalyst for oxidation in the gas f is e, when a fluidized bed of inert carrier put a suspension of particles of TiO2and V2O5in which at least 90 vol.% particle V2O5has a diameter of 20 μm or less and at least 95 vol.% particle V2O5has a diameter of 30 μm or less.

2. The method according to claim 1, characterized in that at least 90 vol.% particle V2O5has a diameter of 15 μm or less and at least 95 vol.% particle V2O5has a diameter of 20 μm or less.

3. The method according to claim 1 or 2, characterized in that at least 50 vol.% particle V2O5has a diameter of more than 2 μm.

4. The method according to claim 1 or 2, wherein the suspension further contains at least one source of cesium, phosphorus and/or antimony.

5. The method according to claim 1 or 2, characterized in that the deposited catalytically active mass contains from 1 to 40 wt.% of vanadium oxide, calculated as V2O5and from 60 to 99 wt.% of titanium dioxide, calculated as TiO2.

6. The method according to claim 5, characterized in that the catalytically active mass contains up to 1 wt.% compounds of cesium, calculated as Cs, up to 1 wt.% compounds of phosphorus, calculated as P, and up to 10 wt.% oxide of antimony, calculated as Sb2O3.



 

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18 cl, 1 dwg, 6 tbl, 14 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 preparing dimethyl-1,5-naphthalene dicarboxylate that is used in preparing polymers based on thereof and articles made of these polymers. The economic and effective method involves the following stages: (1) dehydrogenation of 1,5-dimethyltetraline to yield 1,5-dimethylnaphthalene; (2) oxidation of 1,5-dimethylnaphthalene prepared at dehydrogenation stage to yield 1,5-naphthalene dicarboxylic acid being without accompanying isomerization stage, and (3) esterification of 1,5-naphthalene dicarboxylic acid prepared at oxidation stage in the presence of methanol to yield the final dimethyl-1,5-naphthalene dicarboxylate.

EFFECT: improved preparing method.

9 cl, 3 dwg, 5 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention elates to a method for preparing pure isophthalic acid. Method involves step-by-step oxidation of m-xylene with oxygen-containing gas in acetic acid medium in the presence of catalyst comprising heavy metal salts and halide compounds under increased pressure and temperature up to the definite degree of conversion of m-xylene to isophthalic acid and the following isolation of the end product. Oxidation of m-xylene is carried out for tree steps at discrete change of temperature by steps to side of decreasing and with the following increasing, or increasing with the following decreasing by the schedule: T1 > T2 < T3 or T1 < T2 > T3 in the temperature range 180-200°C in the presence of manganese-cobalt-bromide catalyst modified with additives of zinc and/or nickel salts in the following ratio of metals Mn : Co : Ni = 1:(0.5-2):(0.005-0.01):(0.005-0.01), respectively, in the total concentration of metals 490 p. p. m. in the reaction mass in the equimolar ratio of the amount of bromine with respect to metals and mixing time of reagents added to the reagents zone <10 s. Then oxidized compound from the 3-d step is subjected for cooling, crystalline isophthalic acid is isolated and treated successively by washing out with acetic acid at temperature 80-100°C in the mass ratio isophthalic acid : CH3COOH = 1:(2-2.5) to remove catalyst and with water at increased temperature 150-230°C in the ratio isophthalic acid : water = 1:(2-3) to remove acetic acid. Then the washed out product is isolated and dried by known procedures to obtain highly pure isophthalic acid. Method provides simplifying the process and to improve quality of isophthalic acid.

EFFECT: improved preparing method.

2 tbl, 1 dwg, 10 ex

FIELD: organic chemistry of polymers, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing trimellitic acid anhydride. Method for preparing intramolecular trimellitic acid anhydride is carried out by liquid phase oxidation of pseudocumene with air oxygen for a single stage at increased temperature and pressure under conditions of countercurrent of oxygen-containing gas and reaction products in the presence of a catalyst comprising heave metal salts and halide compounds followed by distilling off a solvent and thermal dehydration of mellitic acid up to its intramolecular anhydride. Oxidation of pseudocumene is carried out in reaction volume separated for three zones wherein hydrogen bromide acid is added to each reaction zone by distributed feeding to provide the discrete increase of the HBr concentration up to [HBr] ≥ 0.052% in the first (upper) zone, [HBr] ≤ 0.09% in the middle (second) zone, and [HBr] ≤ 0.111% in the bottom third) zone. The composition of catalyst is maintained as constant in all zones in the ratio of its components in the limit Co : Mn : Ni = (0.28-0.66):1:0.04, respectively, and the process is carried out in the temperature range 160-205°C by its step-by-step increase in zones in the range: 160-180°C in the upper (first) zone, 180-190°C in the middle (second) zone, and 195-205°C in the bottom (third) zone. Invention provides improving the technological process of oxidation of pseudocumene, to improved quality of the end product and to enhance specific output of the reaction volume. Trimellitic acid anhydride is used broadly in preparing high-quality plasticizers, insulating varnishes, high-temperature polyimidoamide coatings and other polymeric materials.

EFFECT: improved preparing method.

2 tbl, 3 dwg, 16 ex

FIELD: industrial organic synthesis.

SUBSTANCE: aromatic carboxylic acid is obtained via liquid-phase oxygen-mediated oxidation of initial aromatic mix containing benzene bearing two or three oxidizable substituents in its ring or naphthalene bearing at least one oxidizable substituent in its ring in reaction medium containing initial aromatics, promoter, heavy metal-based catalyst, and solvent containing benzoic acid and about 5 to about 60 wt % water, percentage of solvent in reaction medium ranging from 1 to 40 wt %. Oxidation proceeds in reaction zone of double-phase stream reactor under reaction conditions to produce high-pressure emission gas at 160-230°C in first part of reaction zone and at 180-260°C in second part of reaction zone, while at least part of aromatic acid produced crystallizes from reaction medium in reaction zone. According to second embodiment of invention, aromatic carboxylic acid production process comprises (i) providing reaction mixture containing initial aromatic compound, heavy metal-based catalyst, bromine source, and solvent containing benzoic acid and water, initial aromatic compound being benzene bearing two oxidizable alkyl substituents in m- and/or p-positions of its ring or naphthalene bearing oxidizable alkyl substituents in its ring, percentage of solvent in reaction medium ranging from 1 to 40 wt %; (ii) bringing at least part of reaction medium into contact with oxygen-containing gas in first continuously stirred mixing reactor at 160-230°C to form first high-pressure gas stream and product containing crystalline aromatic dicarboxylic acid in liquid medium containing the same, heavy metal-based catalyst, bromine, water, benzoic acid, intermediate oxidation products, and by-products; and (iii) sending thus obtained product to second continuously stirred mixing reactor, wherein second high-pressure gas stream is formed and at least part thereof contacts with oxygen-containing gas at 180 to 260°C to produce aromatic dicarboxylic acid.

EFFECT: minimized toxic methyl bromide formation.

26 cl, 2 dwg

FIELD: waste water treatment.

SUBSTANCE: method comprising deposition of active components onto polymer carrier followed by washing with modifying solution and drying of resulting catalyst is characterized by that above-mentioned polymer carrier is a super-crosslinked polystyrene preliminarily washed with acetone and dried, deposition of active components onto polymer carrier is accomplished by impregnating it for 8-10 min with complex solution of platinum group metal chloride and/or gold-hydrochloric acid sodium salt in concentration 0.57-64.5 g/L in complex organo-alcohol-water solvent containing, in particular, tetrahydrofurane, methanol, and water, whereupon catalyst id dried to constant weight and then optionally washed with modifying solution of sodium carbonate, 2.76-136.74 g/L, and with distilled water to neutral pH = 6.8-7.2. Catalyst allows deep oxidation of phenol compounds at high degree of conversion.

EFFECT: enhanced phenol oxidation activity of catalyst, simplified catalyst preparation technology needing utilization of lesser amounts of expensive chemicals.

3 cl, 3 tbl, 18 ex

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