Crude terephthalic acid purification process and suitable carbonaceous fibers-containing catalysts
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
The invention relates to a method of purification of crude terephthalic acid by hydrogenating treatment on the catalyst, which contains at least one deposited on a carbon carrier metal hydrogenation. The invention relates further to the reactor and containing carbon fiber catalysts, to a method for their production and to their use in particular as a catalyst for hydrogenation.
The greatest amount of terephthalic acid is technically get by way of oxidation in the liquid phase, was developed by the company Amoco, USA. In this method, p-xylene are oxidized by oxygen of the air under pressure in 95%acetic acid using consisting of salts of cobalt and manganese, and compounds of bromine catalyst system. At the end stage of oxidation in the way Amoco required cleaning stage, if the obtained terephthalic acid must then be processed into fibers. Task cleanup phase is mainly a translation of the formed due to partial oxylene 4-carboxybenzene in not interfering or easily detachable connection. Usually produces about 5000 h/mill. 4-carboxybenzene. This connection should be removed because it interferes with the reaction of polycondensation in the further processing of terephthalic acid. On the other hand, is preventing staining yellow p is the FL-condensing.
To resolve this problem, the most widespread additional connection stage hydrogenation, in which an aqueous solution of crude terephthalic acid at a temperature of approximately 250°With pressure treated catalyst based on noble metals deposited on charcoal. When this occurs, the conversion of 4-carboxybenzene in p-Truelove acid, which in contrast to the aldehyde can be easily separated from the desired product of terephthalic acid by crystallization. The basic principle of this method is described in U.S. patent No. 3584039. Used in catalyst carbon carriers are powdered or granular.
With the technical implementation of the method of hydrogenation is usually used bulk catalysts, which typically contain 0.5 wt.% palladium on technically available carbon media that described in application EP-A-0879641. Although the task of hydrogenation can satisfactorily be solved, used in industrial conditions, the catalysts have some drawbacks. In particular, layers of bulk catalysts, which are deposited on carbon as a carrier, have the disadvantage that due to the relatively low mechanical stability of the material of the carrier arising under operating conditions the movements in the catalyst layer has the seat abrasion dust, which must then be removed from the product. In addition, this abrasion is caused by the loss of expensive active components of precious metals. In addition, it is often observed that during operation resulting in loss of expensive active components of precious metals, if they are sufficiently chemically not fixed on a material carrier.
The fixed catalyst bed containing activated carbon fibers, in which the deposition of the marked(s) one or more catalytically active components, as described in the publication DE-A-3229905. Carbon fiber is made as the structure in which they are intertwined with each other and create space-filling condition. When this carbon fiber are similar to the felt form.
Monolithic catalysts used for hydrogenation already for a long time. In the publication EP-A-0827944 describes this method of hydrogenation, wherein the catalyst is applied as a layer, which is preferably monolithic. The catalyst layer is produced by applying at least one catalytically active substance on a fabric, knitted or film material as a carrier.
Drawing on media catalytically active mass can be carried out in various ways. In the application EP-A-0965384 describes how p is the impregnation for applying the catalytically active mass on structured media or monolith. When this is applied a sealing medium which has a surface tension of most 50 mn/m From the structured media get monoliths. Applied to carrier materials can include metal or ceramic substances, and carbon. As described in the application EP-A-0827944, as a catalyst carrier or catalyst is preferably used strips of metallic fabric.
In the international application WO 99/26721 describes how to obtain the catalyst carrier of activated carbon fibers. For this fiber, artificial silk are translated into the fibers of activated carbon and impregnated with catalytically active metals or processed by the method of casinoonline. Describes the shape of the catalyst carrier fabric and other flat substrates. The catalyst used in this fabric form.
Important applications of hydrogenation catalysts is the production and purification of terephthalic acid.
The present invention is to develop a method of purification of crude terephthalic acid and hydrogenation catalysts, which do not have the disadvantages of the known catalysts. The catalysts must, in particular, have high mechanical stability and abrasion resistance and should be used mainly when hydrogenating processing raw terephthalonitrile.
The problem is solved according to the invention a method of purification of crude terephthalic acid hydrogenation treatment catalyst containing at least one metal hydrogenation deposited on a carbon carrier, which used carbon fiber.
Catalytic hydrogenation treatment may be performed, as described in U.S. patent No. 3584039. In particular, the catalyst is used for hydrogenation of 4-carboxybenzene with the formation of p-Truelove acid. Especially preferably the method is carried out at temperatures above 200°and under pressure mainly from 50 to 100 bar. This hydrogenation treatment may be performed continuously or periodically.
When this carbon fiber can be located in the reactor in any suitable form. For example, they can be arranged orderly or randomly, for example, randomly in the form of felt, as described in the application DE-A-3229905, or orderly in the form of a flat product, as described, for example, in international application WO 99/26721. Fit any spatial arrangement of the carbon fibers, which allows the catalytic hydrogenation processing of crude terephthalic acid. It should allow the contact of the crude terephthalic acid with carbon fibers and mass transfer. So carbon fiber is aspolozhena, as a rule, in such a way that a solution of crude terephthalic acid in the catalytic hydrogenation can move along the carbon fibers.
During the continuous supply of the solution of the original acid carbon fiber placed in the reactor, preferably in such a way that the fluid flow through the reactor flows through the carbon fibers. The preferred geometric shape of the carbon fibers are described in detail below.
The catalyst may be in the form of a fabric, knitted fabric, knitted fabric and/or felt, or in the form of parallel fibers or tapes. Parallel fibers or ribbons can be directed along the flow direction in the reactor.
According to one form of the present invention is a flat catalyst has at least two opposite each other edge on which it is fixed in the reactor in order to provide a stable form. Thus preferably a few strips of flat catalyst is parallel to the preferential direction in the reactor, and while they are in space in such a way that during oxalidaceae reactor almost completely or mostly fully prevents abrasion of the bands due to their mutual contact or contact with the reactor walls.
The expression "opposite each other edge" refers to locomo the catalyst, which has two edges bounding surface on both sides. Edges are mainly parallel to each other. They preferably be straight, but may have other forms, for example, they can be wavy or take the form of various other lines. They are preferably parallel to each other, but can form between an angle of up to 20°. The parallelogram, for example, has two similar, parallel to each other opposite edges. A rectangle has two arranged vertically to each other opposite to each other of the pair of edges that limit the rectangle or square. Opposite to each other edge is made according to the invention in such a way that they allow you to mount flat catalyst in the reactor. Fastening is carried out with a stability of form. The term "dimensional stability" means that is fixed in the reactor the catalyst before, during and after operation of the reactor maintains a flat shape and is not compressed into a ball or a bunch. For example, a flat catalyst may be fixed in the reactor, as a direct sail of a sailing vessel. A flat structure is located in the reactor and the reactor is basically not changed.
It is possible, for example, in this embodiment, when the cat the rum in a cylindrical reactor in the upper and lower zones vertically to the longitudinal axis has two grates, between which is clamped a flat catalyst, respectively, are clamped fiber or tape. If parallel to each other grids have several spacers, then a few strips of flat catalyst can be fixed parallel to each other on these mounts. Thus, the term "band" refers mainly rectangular flat areas of the catalyst, which in this flat form attached, respectively, are clamped in the reactor stability in shape. Several flat strips of catalyst is thus predominantly parallel to the preferred direction in the reactor (approximately comparable to the preferred orientation of liquid crystals in the nematic liquid crystal phase). The preferred direction, for example, in a tubular reactor can be carried out along its longitudinal direction. However, it can also be angular position to the longitudinal direction of the reactor. Strip in the reactor are preferably such that their preferred direction coincides mainly with the direction of flow of the reaction mixture.
Stripes located relative to the reactor and relative to each other, preferably in such a way that the abrasion strips resulting from mutual contact or with the walls of the reactor during operation the AI reactor is largely prevented. It is sufficient distance between the bands themselves and between them and the walls of the reactor. A suitable geometry may be determined by simple tests. The resulting abrasion can easily optically be installed in the discharge from the reactor product.
Variations of the above-described possibilities for the geometry of the catalyst, for example, is fixed only in the upper zone (free-hanging) or (partly) attached to the chassis catalyst tissue are also covered in this invention.
The invention relates to a reactor containing a flat catalyst in the form of a fabric, knitted fabric, knitted fabric and/or felt, which contains at least one deposited on the carbon fiber metal hydrogenation and has at least two opposite each other edge, on which the catalyst is fixed in the reactor stability in the form of, or containing catalyst in the form of parallel fibers or tapes. A reactor with a flat catalyst preferably has the above geometry.
According to another form of execution of the invention is applied neuopathy monolithic catalyst. Description carbon fibers and metal hydrogenation, as well as ways to obtain valid for videoporno forms of execution.
The objective of the invention is asaeda according to another form of execution through the catalyst, which contains at least one deposited on a carbon carrier metal hydrogenation and is characterized by the fact that, as the carbon carrier used carbon fiber, and carbon carrier has a surface on BET<500 m2/g, preferably <300 m2/g, particularly preferably <100 m2/g, mainly <50 m2/g and, in particular <10 m2/Grignon limit possible surface BETH carbon media is, in General, the BET surface geometry of the fiber surface, corresponding to a porosity of 0%.
These carbon fibers have a high mechanical stability. For example, the tensile strength of these carbon fibers is approximately 60000 bar, preferably from about 13000 bar to 35,000 bar.
A suitable geometry and other properties of the catalyst according to the invention already described above. Suitable hydrogenation metals are given below.
In addition, the invention is solved by a monolithic catalyst containing at least one catalytically active material containing at least one deposited on a carbon carrier metal hydrogenation and at least one non-catalytically active material and the associated support or skeletal element that provides the mechanical is podporu catalytically active material and held in monolithic form.
Monolithic structures are described, for example, in the publication EP-A-0564830. Monolithic structures differ from those available in the form of particles of catalysts or their carriers so that they are available in much smaller parts than are available in the form of particles (powdery or granular) catalysts. In the reactor the catalyst can be installed in the form of a single monolith or more monolithic parts, arranged in a stack for the formation of the fixed layer. The number of monoliths however small, for example, one catalyst layer is applied from 1 to 10 monoliths. Monoliths, as a rule, have a three-dimensional structure, which has through channels. While the monoliths can have any external shape, for example, cubic, cylindrical, dice, etc. Through the channels can have any geometry, for example, they can be arranged like a honeycomb structure that has a place in the catalyst for purification of exhaust gases. Often monolithic catalysts produce deformation of flat media, for example, by rolling or folding of flat media in three-dimensional monoliths. Based on flat substrates, the external form of monoliths can be a simple way to fit the geometry of the reactor.
It was found that the above problems can be technically simple and economical manner also in the om case, if for hydrogenation in a fixed catalyst layer as a catalyst carrier instead of the usual in the prior art bulk carrier to apply the monolithic catalyst layers. For the monolithic catalyst layers in the sense of the invention refers to such structures in which the flat media, such as a fabric of carbon fibers, first loaded with an active metal hydrogenation and thus obtained activated fabric at the second stage is processed further in the desired monolithic catalyst.
Monolithic structures are characterized, as well as located in the reactor strip, what is possible, a controlled flow of clean liquid through the catalyst layer. The friction of the catalyst particles together in any case prevented. Due to the ordered structure of the catalyst layer obtained improved opportunities for optimal from the point of view of the characteristics of the flow of operation of the catalyst layer with improved misoperations between the reactor phases. Theoretical aspects of optimization potential are discussed, for example, in the publication "Monoliths in Multiphase Catalytic Processes" (CatTech 3 (1999), p.24 and others). All the described monolithic catalysts based on extruded molded products, load active metals which b is more complicated, than in the case of the proposed catalysts, which are preferably receive on the basis of a flat pre-form. In the publication there is only one indication that obtaining monolithic structures is also possible on the basis of thin sheets. The production of such originating from a flat prior structures of the monolithic catalysts are described, for example, in application EP-A-0564830, EP-A-0827944 and EP-A-0965384. Regarding a three-dimensional implementation of the catalysts according to the invention can be referenced in the request.
Monolithic-based carbon fiber material, the catalysts according to the invention is suitable along with the replacement of the conventional catalyst layers, and also for replacement of catalysts that are used in suspended form in the carbon media. Such catalysts are used primarily in numerous ways hydrogenation, in particular, in the field of fine chemicals. When implemented these in most cases periodically ways the catalyst must be separated from the reaction mixture after the reaction. It is or sedimentation, or filtration. The catalysts according to the invention are distinguished by the fact that at the same hydrogenation activity they can be a simple way isolated from the reaction mixture without the use of conventional more or less complex operations as a Result there is a reduction of production cycle time and improve the efficiency of the method. In many cases, used for the suspension hydrogenation reactor may further be used to receive the monolithic catalyst unit after making minor technical modifications.
Monolithic catalysts according to the invention are a combination of catalyst and skeletal or support element.
At least one skeleton or supporting element serves to provide a stable and permanent form deposited on a carbon fiber catalytically active metals. When this carbon fiber in the catalyst are mainly in the form of a fabric, knitted fabric, knitted fabric and/or felt. Especially preferably, they are present in the form of a fabric or knitted fabric, in particular in the form of a fabric. Suitable carbon fibers are described, for example, in the applications DE-A-3229905, WO 99/26721 and source Ullmann''s Encyclopedia of Industrial Chemistry, Section: Fibers, Synthetic Inorganic, Composite Materials Carbon Fibers. You can use any suitable carbon fibers. Such fibers according to the prior art is obtained from polyesters, polyamides, polyolefins, etc. According to the invention particularly preferred fiber, fabric, knitted fabric, knitted fabric or felt with the following properties: specific density of from 80 to 600 g/m2the density of threads from 3 to 15 threads/cm, the diameter of the filaments from 0.1 to 0.9 mm, Especially predpochtitel what about the use of high-strength at break of the fiber bundles. The BET surface is preferably less than 300 m2/g, particularly preferably less than 100 m2/g, in particular less than 15 m2/year Porosity is preferably less than 0.5 ml/g Suitable fiber sold by the company Tenax Fibers. Such fibers are described in the Internet under the address textileworld.com.
The catalyst is associated with skeletal or support element. This skeleton or supporting element provides mechanical support for the catalyst and holds it in monolithic form. In particular, the fabric of carbon fibers are often insufficient for use in a fixed bed mechanical properties such as rigidity and dimensional stability. Therefore, according to the invention connect them with one or more reference or skeletal elements, resulting catalyst is mechanically stabilized and held in the desired monolithic form. This prevents deformation of the catalyst due to shock and flow through him reagents. Support or skeletal element may be of any usable form. Connection with the catalyst can be made in any manner, for example by crackadobe fastening, gluing, and the like, and also connections through joint knitting and making into the fabric of carbon fibers and the priori and skeletal element.
Preferably, at least one flat support or skeletal element exists in the form of fabrics, knitted fabrics, knitted fabrics, felt and/or perforated material. These flat items can be wavy or fold. Particularly preferably flat support or skeletal elements and the catalyst to form alternating layers in the monolithic catalyst. Support or skeletal element may be made of any suitable material, for example, from metals or alloys, plastics or ceramics. Concerning the used materials should indicate on the application EP-A-0965384, descriptions section related media catalyst. Especially preferably the support or skeletal element is made of chemically resistant materials.
According to the form of execution of the invention as a catalyst, and at least one reference or skeletal element is made preferably in the form of fabric as flat layered structure, which is formed in a cylindrical monolith with a few parallel to the longitudinal axis of the cylinder flow channels, i.e. the channels through which flow of the reactants.
The catalyst contains at least one deposited on the carbon fiber metal hydrogenation. As a metal hydrogenation may be applied to all metals, to the which catalyze the hydrogenation of organic compounds. Preferably in this case we are talking about the metals of group VIII or IB of the Periodic system of elements. The hydrogenation metals are applied to the carbon fibers by known methods and in normal quantities. Suitable methods of application on the active mass media described in the application EP-A-0965384. Can also be used and other ways of applying the catalytically active metals on the carbon fibers and their fixation on them. Carbon fiber carbon can be obtained, for example, by oxidation of polymer fibers, and active metals can be deposited on the carbon fiber or made to them. They can also be applied additionally. For example, obtaining a monolithic catalyst can be carried out first with the use of polymer fibers in a suitable form, for example, in the form of fabric, and then the polymeric material are oxidized with the production of carbon fibers, respectively, of the fabric of them.
The invention relates also to a method for producing a monolithic catalyst separate receiving catalyst and at least one reference or skeletal element, connecting them and forming a monolith.
Monolithic catalysts, as well as the above-described reactors can be used for hydrogenation of unsaturated organic compounds. They can also be used for selective guide is investing double and triple carbon-carbon bonds and/or hydronamic functional groups, moreover, double and triple carbon-carbon links and gidriruemyi functional groups found in organic compounds. How selective hydrogenation is described, for example, in application EP-A-0827944. Gidriruemyi functional groups are, for example, nitro group, carbonyl group, carboxyl group, etc. Selective hydrogenation of the double or triple carbon-carbon bonds can be, for example, in the presence of the aromatic nuclei, and the aromatic nucleus is not hydronauts.
Particularly preferably monolithic catalyst and the reactor according to the invention are used for the purification of crude terephthalic acid by catalytic hydrogenation treatment. The invention relates also to the appropriate cleaning method.
As a catalyst for hydrogenating treatment is applied monolithic catalyst which contains palladium as the noble metal on carbon fibers. In the case of carbon fabric, the proportion of palladium is preferably from 10 to 5000 mg Pd/m2carbon fabric.
The invention is illustrated by the following examples.
Obtaining a solid catalyst based on palladium and coal is carried out using 0,98 m2carbon fiber fabric company the Fibers Heat that is not the how many times causing an aqueous solution of palladium. In General cause 910 mg of palladium per 1 m2carbon fabric. The application is carried out, as described in the application EP-A-0965384. Get palladium carbon fabric with the following properties:
Unit weight: 92 g/m2
The Pd content: 1%
Specific surface area: 4,4 m2/g
Test for the activity of the hydrogenation hydrodegradable (GDP) obtaining hydromineral (Mr. Lin)
The piece of fabric with a width of 0.2 m and a length of 0.6 m from example 1 are processed by the layers together using a wave-like fabric made of stainless steel in a cylindrical monolith, which contains many parallel to the longitudinal axis of the cylinder through channels. The walls of the channels consist of the loaded noble metal on a carbon cloth. Fabric-based stainless steel has the task to mechanically stabilize the monolith.
The resulting monolith is inserted into the periodically operating the circulation reactor, in which hydronaut 0.5 kg net hydrodegradable (GDP) without solvent. The pressure of the gas and the liquid in the cross section is each 200 m3/m2/PM
Using gas chromatography to determine the following activity for hydrogenation.
The rate of hydrogenation is Mr. Lin 17%GDP/h, which corresponds to the output in terms of volume and time 1,12Mr. Lin/lcat/hour, a Mixture of the desired product, astae the Xia transparent, as water.
After dismantling the catalyst monolith is in mechanically perfect condition.
Hydrogenation of 4-carboxybenzene in the solution of terephthalic acid, loss of palladium.
54 g of crude terephthalic acid in 146 g of water hydrogen treated at 250°C for one week on obtained according to the example of the 2 monolithic catalyst. Then analyze how vykristallizovalsya fraction of terephthalic acid, and the aqueous supernatant on the palladium content.
Catalyst unit after dismantling is in mechanically perfect condition, no traces of any abrasion in the resulting product. Also in both factions no traces of palladium.
In the autoclave serves 146 g of water and 54 g of crude terephthalic acid (2000 h/mil. 4-carboxybenzene, color: light yellow) and 8 g obtained in example 1 catalyst in the form of a fabric. The mixture at 270°and a pressure of 50 bar hydrogen atmosphere is stirred for 60 hours. The resulting product consists of white crystals of terephthalic acid with polarographically certain content 4-carboxybenzene <50 mg/kg
1. The method of purification of crude terephthalic acid catalyzed by hydrogenating additional processing on the catalyst material, which contains at least one deposited on a carbon carrier metal hydrogenation, characterized in that as the carbon carrier used carbon fiber, in which the catalyst material is made planar in form, fabric, crocheted, knitted and/or felt material or in the form of parallel fibers or tapes, and planar katalysator the second material has at least two opposite each other edge, on which the catalyst material is fixed in the reactor stability of form, or as a catalyst applied monolithic catalyst containing at least one catalyst material, which contains at least one deposited on the carbon fiber metal hydrogenation and at least one non-catalyst material and the associated support or skeletal element, which is mechanically supported catalyst material and holds it in monolithic form.
2. The method according to claim 1, characterized in that a lot of bands planar catalyst material extends parallel to the preferred direction in the reactor and is located in the space so that basically prevents abrasion of the bands due to touch them with each other or with the walls of the reactor during reactor operation.
3. The method according to claim 2, characterized in that the strips are arranged in the reactor in such a way that their preferred direction corresponds with the direction of flow of the reaction mixture.
4. The method according to claim 1, characterized in that the monolithic catalyst, at least one support or skeletal element is made of metal, plastic or ceramics.
5. The method according to claim 1 or 4, characterized by the eat, in the monolithic catalyst, at least one support or skeletal element is made planar in form, fabric, crocheted, knitted, felted material and/or perforated sheets.
6. The method according to claim 5, characterized in that the monolithic catalyst support or skeletal element and the catalyst material are as alternating layers in the monolith.
7. The method according to claim 6, characterized in that the monolithic catalyst catalyst material is in the form of a fabric, and at least one supporting element is made of metal in the form of fabric there as planar layers, which is formed in a cylindrical monolith with many parallel to the longitudinal axis of the cylinder flow channels.
8. A monolithic catalyst for the purification of crude terephthalic acid containing at least one catalyst material, which contains at least one deposited on the carbon fiber metal hydrogenation and at least one non-catalyst material and the associated support or skeletal element that is supported catalyst material mechanically and holds it in monolithic form.
31.01.2001 - 8;
27.08.2001 - claims 1 to 7.
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: industrial production of methacrylic acids at reduced amount of industrial wastes.
SUBSTANCE: proposed method is performed by catalytic oxidation of propane, propylene or isobutylene in vapor phase at separation of final product and forming of high-boiling mixture as by-product which contains (according to Michaels addition) water, alcohol or methacrylic acid added to methacrylic group. By-product is decomposed in thermal decomposition reactor at simultaneous distillation of decomposition products in distilling column from which methacrylic acid is taken in form of distillate. Flow of liquid decomposition residue is forced for peripheral direction by means of mixing blades before withdrawal from reactor. Peripheral direction is obtained with the aid of liquid fed from the outside of decomposition reactor; to this end use is made of initial high-boiling material or flow of liquid discharged from decomposition reactor. If necessary, etherification stage is performed through interaction with alcohol for obtaining methecrylic ester. Decomposition of by-product formed at obtaining methacrylic acid by oxidation of propylene or isobutylene or at obtaining methacrylic acid by interaction of acid with alcohol by alcohol through introduction of by-product into thermal decomposition reactor provided with distilling column which has plates made in form of disks and toroids for simultaneous decomposition and distillation. Plant proposed for realization of this method includes thermal decomposition reactor and distilling column, level meters and lines for discharge of liquid containing easily polymerized compounds. Level indicator mounted at area of accumulation of liquid shows pressure differential. Line for detecting the side of high pressure of this level meter is connected with accumulated liquid discharge line.
EFFECT: updated technology; increased yield of target products.
38 cl, 14 dwg, 2 tbl, ex
FIELD: chemical technology.
SUBSTANCE: invention relates to technology for synthesis of acetic acid by the cabonylation reaction of methanol with carbon monoxide. Method involves preparing the productive flow in the reaction section containing acetic acid, acetaldehyde, water and other impurities. In the cleansing treatment the reaction products are subjected for treatment wherein acetaldehyde impurities are oxidized to either acetic acid after its isolation and recovered to the reaction zone or to carbon dioxide and water that removed from the system. As result, method provides excluding the negative effect of acetaldehyde at step for separation of the reaction products. Oxygen, air or their mixtures, ozone, carbon peroxide or peracetic acid are used as oxidant. As possible variants of the method, the productive flow is fed to distillation column wherein flow of light products or heavy products are isolated under condition that each of these flow involves acetic acid, acetaldehyde and water. Then "light" or "heavy" flow is subjected for oxidation as said above to reduce the concentration of acetaldehyde. As a variant of the method the flow of heavy products can be treated by extraction with water followed by oxidation of acetaldehyde-containing aqueous phase. Invention provides improvement of method due to exclusion of the necessity of purification of the end product from acetaldehyde impurity.
EFFECT: improved treatment method.
20 cl, 3 tbl, 35 ex
FIELD: industrial organic synthesis.
SUBSTANCE: method comprises contacting vapor-phase mixture at 150-205°C with alkali and/or alkali-earth metal carboxylate dispersed on activated carbon resulting in conversion of alkyl iodides into corresponding carboxylic acid esters, while iodine becomes bound in the form of inorganic iodide.
EFFECT: facilitated freeing of carboxylic acid product from organic iodine compounds.
4 cl, 2 tbl, 32 ex
FIELD: chemical technology.
SUBSTANCE: invention relates to the improved method for extraction of carbonyl and (or) acid compounds from the complex multicomponent organic liquid mixtures. Method involves treatment of organic liquid mixtures with sodium sulfite an aqueous solution at intensity of mechanical stirring providing formation of uniform emulsion. The content of carbonyl compounds and acids in the parent mixture to be treated is determined and treatment is carried out with 4.16-26% aqueous solution of sodium sulfite as measured 1.05-1.1 mole of sodium sulfite per 1 g-equiv. of carbonyl compound, and in exceeding of the content of acids (g-equiv.) in the parent mixture over the content of carbonyl compounds - with 1 mole sodium sulfite per 1 g-equiv. of acids and in the mass ratio of sodium sulfite aqueous solution to organic mixture = (1-2.5):(2-1) at temperature 15-30°C; if the content of acids in the parent mixture (g-equiv.) is less the content of carbonyl compounds (g-equiv.) then under control of pH value change in an aqueous phase method involves additional addition of mineral or organic acid in the amount as a difference in the content of carbonyl compounds (g-equiv.) and the content of acids (g-equiv.) in the parent charge of organic mixture per treatment at such rate that pH value of aqueous would decrease constantly but not less 6.5. This simple method provides removing both carbonyl compounds and acids being without significant limitations for the content of carbonyl compounds and acids in the parent mixture. Invention can be used in different branches of industry for treatment of compositions or for utilization of carbonyl compounds and (or) acids.
EFFECT: improved method for extraction.
5 cl, 3 tbl, 26 ex
FIELD: organic chemistry, chemical technology.
SUBSTANCE: invention relates to a method for purifying naphthalene carboxylic acid. Method involves contacting crude naphthalene acid with solvent used for purifying in the presence of hydrogen and catalyst that comprises a precious metal of VIII group taken among palladium, platinum and ruthenium and metal of group IVB taken among silicon, germanium, tin and lead at temperature about from 520 to 575°F. Proposed method provides preparing reduced amount of organic pollution in purified acid as compared with other methods of purification.
EFFECT: improved purifying method.
19 cl, 1 dwg, 5 tbl, 5 ex
FIELD: chemical technology.
SUBSTANCE: invention relates to the improved method for treatment of organic mixtures from carbonyl compounds and acids by their treatment with sodium sulfite. Method involves using organic mixtures comprising carbonyl compounds and carboxylic acids in the ratio = 1 g-equiv. : 1 g-equiv. or with excess of acids, or with excess of carbonyl compounds. In this case before treatment with sodium sulfite carboxylic acid is added to the parent mixture in the amount to obtain the ratio of carbonyl compounds to acids as 1 g-equiv. per 1 g-equiv. and treatment is carried out with solid sodium sulfite in beaded mill with the mass ratio of the composition charge to glass beads as a grinding agent = 1:(1-2) at the rate of mechanical mixer rotation 1440 rev/min, not less, and in dosing sodium sulfite 1.2-1.5 mole per 1 g-equiv. of carbonyl compounds or excess of acid in the presence of stimulating additive up to practically complete consumption of carbonyl compounds, or carbonyl compounds and acids. Process is carried out in the presence of sodium and potassium hydroxide and acetate and sodium nitrate also as a stimulating additive taken in the amount 1-4% of mass sodium sulfite to be added up to practically complete consumption of carbonyl compounds and acids in composition to be treated. This simple method provides high degree of purification being even in small parent content of carbonyl compounds and acids.
EFFECT: improved method for treatment.
4 cl, 3 tbl, 19 ex
FIELD: exhaust gas afterburning means.
SUBSTANCE: invention relates to catalytic neutralizer for treating internal combustion engine exhausted gases. Proposed catalyst is composed of catalytically active coating on inert ceramic or metallic honeycomb structure, wherein coating contains at least one platinum group metal selected from series including platinum, palladium, rhodium, and iridium on fine-grain supporting oxide material, said supporting oxide material representing essentially nonporous silica-based material including aggregates of essentially spherical primary particles 7 to 60 nm in diameter, while pH of 4% water dispersion of indicated material is below 6.
EFFECT: increased catalyst activity and imparted sufficient resistance to aggressive sulfur-containing components.
27 cl, 2 dwg, 7 tbl, 6 ex