Method and apparatus for producing aromatic carboxylic acids

FIELD: chemistry.

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

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

45 cl, 2 dwg

 

The scope of the invention

This invention relates to a method and apparatus for the production of aromatic carboxylic acids by oxidation of aromatic raw materials in the crude aromatic carboxylic acid in the reaction mixture of liquid-phase oxidation and separation at high temperature and pressure off-gas liquid-phase oxidation for separation of liquid water and liquid solvent oxidation reaction and separation of by-products of oxidation in the liquid and in the gas phase, which are also formed in the result of the division.

Background of invention

Terephthalic acid and other aromatic carboxylic acids are widely used in the production of polyesters, typically by reaction with ethylene glycol, the highest alkylenglycol or their combinations for transformation into a fiber, film, containers, bottles and other packaging materials and molded products.

In the industry of aromatic carboxylic acids are usually obtained by liquid-phase oxidation methylseleninic benzene and naftalina, in which the position of methyl substituents correspond to the provisions of the carboxyl groups in the resulting aromatic carboxylic acid, in a solution of aqueous acetic acid of air or other oxygen source, usually a gas, in the presence of bromine-promoted catalyst, with the holding cobalt and manganese. The oxidation is exothermic and leads to the formation of aromatic carboxylic acids together with byproducts, including products of incomplete oxidation or intermediate oxidation products of aromatic raw materials and products of the reactions of acetic acid, such as methanol, methyl acetate and methyl bromide. As a by-product water is formed. The aromatic carboxylic acid is usually together with by-products of oxidation of the feedstock is formed in solution or in suspension of solids in a liquid reaction mixture, and can usually distinguish the crystallization and separation of solid and liquid substances.

The exothermic oxidation reaction is typically conducted in a suitable reaction vessel at elevated temperature and pressure. The reaction mixture is maintained within the vessel in a liquid state and the vapor formed from the liquid phase when the exothermic oxidation is removed from the reactor to control the reaction temperature. The vapor phase contains water vapor, vaporized acetic acid, a solvent, and a small amount of by-products of oxidation, including by-products formed from the solvent and raw materials. It usually contains oxygen that is not consumed in the oxidation, a small amount of unreacted raw materials, oxides ug is erode, and if the source of oxygen is air or another oxygen-containing gas, the nitrogen, oxides of carbon and other inert gas components of the original gas.

Pure aromatic carboxylic acid is often used for the production of polyesters for such important applications as the manufacture of fibers and bottles because it is known that impurities such as by-products formed from aromatic raw materials during oxidation, and often different carbonization aromatic compounds, cause staining of polyesters derived from acids, and partially lead to the staining of the products of transformations of polyesters. Aromatic carboxylic acid with a low concentration of impurities can be obtained by subsequent oxidation described above raw foods liquid-phase oxidation with one or more successively lower temperatures and oxygen concentrations and crystallization for separation of oxidation products with the aim of making products of incomplete oxidation of the raw materials in the desired acid as it is known from U.S. patent 4877900, 4772748 and 4286101. Preferred pure samples of terephthalic acid and other aromatic carboxylic acid with reduced levels of impurities, such as purified terephthalic acid, or a "MOUTH", produced by the catalytic hydrogenation of the less pure the samples acid, such as crude products containing aromatic carboxylic acid and by-products formed during liquid-phase oxidation of aromatic raw materials, or so-called products average purity in solution at elevated temperature and pressure in the presence of a catalyst based on a noble metal. In the industry of liquid-phase oxidation of alkylaromatic feedstock in the crude aromatic carboxylic acid and purification of the crude product are often carried out in a continuous integrated process in which the crude product is a liquid-phase oxidation is used as the feedstock for cleaning.

Vapor phase formed in the liquid-phase oxidation at high temperature and pressure, is a potentially valuable source of acetic acid, which is used as the solvent, unreacted materials, by-products of the reaction and energy. However, the high water content, high temperature and pressure and corrosion properties of some components, such as gaseous methyl bromide, acetic acid and water, create technical and economic problems with the division or allocation of components to return to the process and the use of contained energy. In addition, the remaining separated impurities in the selected process streams, if they are aware of the negative impact on other variants of the method or quality of the product, may prevent reuse of process streams. For example, as described in U.S. patent 5200557, monocarboxylic acids adversely affect the hydrogenation catalysts used in the methods of cleaning, and acetic acid even in such low concentrations in which it is present in the crude aromatic carboxylic acids, isolated from the liquid phase oxidation reaction, is very undesirable.

In the British patent 1373230, U.S. patents 5304676; 5723656; 6143925; 6504051, European patent 0498591 B1 and international application WO 97/27168 describes how the production of aromatic carboxylic acids by liquid-phase oxidation of aromatic raw materials, in which the exhaust gas of high pressure is removed from the reaction section and process for separation and recycle of part of the components and in some cases, utilization of energy. The condensation of the exhaust gas, as in U.S. patent 5304676, effective for the allocation of water, acetic acid and other condensed components of the exhaust gas; however, the allocation of water, acetic acid and other components of the obtained condensate is technically difficult and economically unfeasible task. The separation of the exhaust gas at high pressure, as in the way the U.S. 5723656, 6143925, 6504051 and WO 97/27168, may be effective for the separation of the exhaust gases with the aim of identifying fluids,enriched acetic acid, and water-containing gases suitable for further processing. However, this way of sharing some by-products of oxidation can be both in liquid and gas phases, which complicates their separation and may have a negative impact on other process flows and stages. These difficulties are exacerbated by the accumulation of such products in those processes in which separate streams of by-products, such as the mother liquor after separation of pure aromatic carboxylic acid from the purified liquid reaction mixture or liquid-condensed off-gases of high pressure. None of the cited patents, the liquid condensate flue gas of a high pressure after the liquid-phase oxidation is not used as a solvent or other water-containing liquid for cleaning contaminated with aromatic carboxylic acids, and the selection of materials and energy in such ways often spend one by another, for example due to loss of cooling energy or pressure relief for separation of substances, incineration substances for regulation of air emissions and other losses of solvent oxidation, raw materials and by-products, if the vapour phase at high temperature and pressure after oxidation is not cool and not relieving the pressure for the removal of such substances.

PR is MESI, the remaining streams of recycling, can disrupt the workflow and reduce the quality of the product. Additional equipment and stage of the process can further complicate the method and limit its practical application, because they raise the cost that outweighs the savings in materials and energy. The role of these factors, loss of energy and materials are multiplying in the implementation process. In the global production with an annual output of 500000-1000000 and tons more product even one per cent, or hundreds of ppm losses of raw material and solvent or transformation of raw materials into unnecessary or unused by-products, small inefficiencies in the allocation of energy and the growing need to process waste waters into significant practical loss, increased fuel consumption or electricity and the need for additional processing, as well as lead to unpredictable effectiveness and efficiency of the method due to the difference in the cost of energy and materials and the requirements to the emission of gaseous and liquid products.

The invention

The present invention provides a method and apparatus, which in various forms and distinctive features provide aromatic carboxylic acids by liquid-phase oxidation of aromatic coal is dorodnova raw materials with improved processing vapor phase high pressure formed by liquid-phase oxidation by division and separation of the solvent oxidation reaction, water and by-products of oxidation. In some embodiments, the invention may also provide an advantageous way of using energy of exhaust gases of oxidation.

The invention also provides improved methods and apparatus for the production of aromatic carboxylic acids with selective regulation of the composition of the by-products of the oxidation of aromatic raw materials and solvent reactions oxidation of monocarboxylic acids formed during liquid-phase oxidation and falling in the exhaust gas of the oxidation reaction or otherwise present when processing the exhaust gas, with the aim of separating water and solvent oxidation reactions. Preferably, such products were distributed depending on the variants of the invention in one or more liquid phases containing solvent oxidation reaction or the water that separates the high pressure steam high pressure phase formed during liquid-phase oxidation, or from the high-pressure gas generated during the separation. Under other equal conditions, the regulation of such products according to the invention can reduce their concentration in the form of impurities in the liquid or steam flows derived from the exhaust gases. This can is also to facilitate the return of such products at the stage of the process, in which they are used more directly or in higher concentrations than if they remained without such distribution in the liquid and vapor phases formed during the separation.

In complex ways to produce pure aromatic carboxylic acid comprising oxidizing an aromatic feedstock in the liquid reaction mixture to a crude product containing aromatic carboxylic acid and by-products of the oxidation of the raw materials, and purification of the crude product by hydrogenation of his solution to the water-containing liquid, the invention may also eliminate or reduce requirements for demineralised water or clean water from other sources and offer a balance of water formed in the reaction of liquid-phase oxidation, and water used for cleaning to a higher level, which has not previously been achieved in the known methods. Aside from the practical separation of solvent and water from the exhaust gas of the oxidation reaction in the liquid phase, suitable for return or use on stages of oxidation and purification, a new way of offering options that include the direction of separation as phlegmy liquid from the solution of the cleanup phase, which contains the mother liquor after separation of the purified aromatic carboxylic acid. In such scenarios, you can return to the process oxidized the I not only such by-products of oxidation, as, for example, intermediate products - carboxybenzene and Truelove acid, which can become the target of an aromatic acid is terephthalic or isophthalic acid, but also of monocarboxylic acid used as the solvent, for example residues of solvent in the crude aromatic carboxylic acids used in the cleaning solutions, and by-products of the oxidation of the solvent remaining in the gases after separation.

In other embodiments, the selection of monocarboxylic acid, a solvent, reaction products of liquid-phase oxidation of unreacted aromatic substrate in oxidation or combinations thereof, present in the vapor phase high pressure remaining after separation of the solvent monocarboxylic acid and water in the vapor phase oxidation, even better due to the condensation of high pressure gas after the separation with the goal of fluid containing water and receiving exhaust gas from the condenser, the high pressure, cooled to a temperature at which one or more irrigation reagents effective in removing one or more substances from the raw material, solvent and by-products of the oxidation of the solvent. The resulting gas can be processed further to separate the raw materials and/or byproducts of the oxidation of the solvent, the next version of the stream, containing raw materials, by-products of the oxidation of the solvent, or combinations thereof, can be used for liquid-phase oxidation.

In one aspect the invention provides apparatus for the production of aromatic carboxylic acids. The apparatus has a high potential energy and conservation of materials in the workflow. In some embodiments, the apparatus is designed in such a way as to reduce the corrosiveness of the process gas flows, so that the details of the apparatus and in some cases, additional equipment can be manufactured from metals and alloys with moderate corrosion resistance such as stainless steel, mild steel or two-phase steel, instead of steels, titanium and Nickel alloys and other more expensive metals with high corrosion resistance, which is traditionally used in the production of aromatic carboxylic acids.

Briefly, the apparatus of the present invention is designed to separate the components of the exhaust from the reactor gas, formed during the production of aromatic carboxylic acids by liquid-phase oxidation of a substituted aromatic hydrocarbon in the liquid reaction mixture, and includes mostly columnar, and a closed vessel, comprising (a) at least one lower input gas feed to the first stage section of the fra is ment of the upper ring-steam high-pressure phases, removed from the reaction vessel liquid-phase oxidation of substituted aromatic hydrocarbons with gaseous oxygen in a liquid reaction mixture containing the solvent monocarboxylic acid and water, in the conditions under which retains the liquid reaction mixture and top zipper steam high pressure phase containing the solvent monocarboxylic acid and water vapor formed in the reaction vessel; (b) the fractionation section for contacting gas and liquid phases in countercurrent many theoretical equilibrium stages, including (1) the first part designed primarily for the separation of water and solvent monocarboxylic acid in the vapor phase high pressure by contact with a countercurrent of phlegmy, which contains components phlegmy obtained at an intermediate stage of the fractionation section, so that the first liquid phase enriched monocarboxylic acid is selected in the phlegm and forms a first intermediate vapor phase high-pressure - depleted solvent monocarboxylic acid and the first portion flows into the intermediate section of a fractionating to get out of phlegmy and the inclusion of the first intermediate vapor phase and transferring phlegmy, of which the first liquid phase is removed in the reservoir fluid; (2) intermediate frequent is, designed for the separation of water and by-products of liquid-phase oxidation of substituted aromatic hydrocarbons in the first intermediate vapor phase in contact with a countercurrent of phlegmy containing liquid components phlegmy obtained from the upper part of the separator, so that the by-products of transformations of the original aromatic hydrocarbons are removed in the phlegm and forms the second intermediate steam high pressure phase containing water vapor with virtually no solvent monocarboxylic acid and by-products of the oxidation of the original aromatic hydrocarbon, and an intermediate portion joined by a stream from the upper part of the fractionation section for receiving therefrom phlegmy and transferring the second intermediate vapor phase; and (3) the upper part designed primarily for the separation of water and by-products of liquid-phase oxidation of solvent monocarboxylic acid is at least one of the second intermediate steam phases and in the phlegm supplied to the upper part, in contact with a countercurrent of phlegmy, so that the second liquid phase containing water without solvent monocarboxylic acid and by-product, is removed in the phlegm and forms a second steam high pressure phase containing water vapor and by-products of the oxidation solvent is - monocarboxylic acid with virtually no by-products of the oxidation of the original aromatic hydrocarbon, with the upper portion collects in the lower part of at least part of phlegmy, which removes the second liquid phase; (C) a reservoir for receiving fluid from the first part of the section of the fractionating phlegmy, which was removed first liquid phase; (d) at least one output fluid communication with a reservoir of fluid for removing liquid from the apparatus; (e) at least one liquid inlet for introduction of phlegmy in the upper part of the fractionation section; (f) at least one liquid inlet for supplying phlegmy in the upper area of the lower part of the fractionation section; (g) at least one outlet fluid connection with the proceedings for removal from the device at least part of phlegmy, which removes the second liquid phase.

In a more specific embodiment, the fractionation section preferably comprises about 20-80 theoretical equilibrium stages. In another embodiment, in the first part of the section of the fractionation can separate water and solvent monocarboxylic acid in the high-pressure steam generated in the liquid-phase oxidation, so that about 95 wt.% the solvent monocarboxylic acid - have been removed in the phlegm. In another embodiment, the first part of the section of fractionation with testvol about 20-70 theoretical equilibrium stages. In the following embodiment, it is preferable that at least one output in communication with the collector for remote phlegmy, which was removed a second liquid phase, and at least one input for filing phlegmy in the upper area of the lower part of the section of the fractionation were divided roughly 1-10 theoretical equilibrium stages. In yet another embodiment, at least one output and at least one input for supplying phlegmy in the upper area of the upper part of the fractionation section is divided roughly 1-10 theoretical equilibrium stages.

Apparatus according to another variant of the invention preferably is a reaction vessel for liquid-phase oxidation of a raw material - substituted aromatic hydrocarbons with gaseous oxygen in a liquid reaction mixture containing the solvent monocarboxylic acid and water, in the conditions under which retains the liquid reaction mixture and in the upper chase the reaction vessel is formed in the vapor phase high pressure, and the reaction vessel contains at least one hole for removal of vapor phase high pressure in the upper pursuit, which is connected at least one bottom gas inlet for receiving and feeding the vapor phase high pressure in the upper chase on the first stage section of the fractionation apparatus p is selenia.

In other embodiments, the device according to variants of the invention are preferably adapted for use in the methods with simultaneous production of pure forms of aromatic carboxylic acids, comprising contacting the solution containing the aromatic carboxylic acid and impurities dissolved in the aqueous medium, with hydrogen in the presence of a hydrogenation catalyst at elevated temperature and pressure with the formation of the reaction mixture after purification and isolation of the solid aromatic carboxylic acid with reduced levels of impurities from the reaction mixture treatment. The preferred apparatus for the production of purified aromatic carboxylic acid such method includes at least one reaction vessel intended for contacting the liquid reaction solution with hydrogen at elevated temperature and pressure in the presence of a hydrogenation catalyst to form a liquid reaction mixture cleaning, and more preferably at least one receptacle for receiving the liquid reaction mixture for purification and extraction of product in contact with the reaction vessel and the discharge from her solid aromatic carboxylic acid with reduced levels of impurities. Preferably, such a device include one or more additional vessels, for example, clerestorey crude or impure aromatic carboxylic acid in a solvent for cleaning, filtration or other method of separation of solid purified aromatic carboxylic acid from the liquid medium and washing the resulting solid purified aromatic carboxylic acid.

Apparatus according to this variant of the invention may also include means for recycling energy in the form of work or by heat dissipation of the second vapor phase high pressure coming out of the machine division.

In another aspect the invention provides a method of producing aromatic carboxylic acids. This method comprises contacting the feedstock containing at least one precursor of acid in the form of aromatic hydrocarbons with gaseous oxygen in a liquid oxidation reaction mixture containing the solvent monocarboxylic acid and water in the presence of a catalytic composition comprising at least one heavy metal section of the reaction at elevated temperature and pressure sufficient to maintain liquid-phase reaction mixture and oxidation of aromatic carboxylic acid and impurities comprising the reaction by-products dissolved or suspended in the reaction mixture of liquid-phase oxidation, and steam with high pressure phase containing the solvent monocarboxylic acid, water and a small amount of the original aromatic hydrocarbon and by-products of the oxidation of the original aromatic hydrocarbon and solvent - monocarboxylic acid; transferring the vapor phase high pressure taken from the section of the reaction section of the separation, where you can almost divide the solvent monocarboxylic acid, water and by-products of the oxidation of at least one enriched solvent monocarboxylic acid - the first liquid phase and at least a second liquid phase and the solvent monocarboxylic acid and at least one enriched water, the second liquid phase, which contains practically no solvent monocarboxylic acid and at least one second steam of the high pressure phase depleted in solvent monocarboxylic acid containing water vapor, so the by-products of the oxidation of the original aromatic hydrocarbon preferably distributed in the first liquid phase and by-products of the oxidation of the solvent monocarboxylic acid is preferably distributed to the second steam phase high pressure; and the removal of the partition separating the separate threads of the first liquid phase enriched solvent monocarboxylic acid, and a second liquid phase enriched water, which is almost free of solvent monocarboxylic acid and by-products of its oxidation, and the second steam of the high pressure phase, which contains almost no side products is offering the oxidation of the original aromatic hydrocarbon.

In other embodiments, the separation of water and solvent monocarboxylic acid and by-products is carried out in section separation, irrigated phlegm, which preferably is a liquid containing water, and more preferably a condensate containing water, condensed from the second vapor phase high pressure discharged from the section of the separation, or the mother liquor remaining after separation of the solid pure forms of aromatic carboxylic acid from the reaction mixture for cleaning, or a combination of both. In another specific embodiment, the section division is divided into stages, and the first phlegm supplied to the main stage separation of water and solvent monocarboxylic acid, contains the mother liquor phase, and additional phlegm supplied to the phase distribution of the by-products of the oxidation of the solvent in the second steam of the high pressure phase, contains the liquid condensate is separated from the second vapor phase high pressure.

In another embodiment, the invention provides a method of producing an aromatic carboxylic acid, including, in stages, at least one stage of liquid-phase oxidation, comprising the contacting of the feedstock containing at least one substituted aromatic hydrocarbon in which the substituents can oxidize to carboxylic gas is brosnam oxygen in the reaction mixture of liquid-phase oxidation, containing the solvent monocarboxylic acid and water in the presence of a catalytic composition comprising at least one heavy metal section of the reaction at elevated temperature and pressure sufficient to maintain liquid-phase reaction mixture and oxidation of aromatic carboxylic acid and impurities comprising the reaction by-products dissolved or suspended in the reaction mixture of liquid-phase oxidation, and steam with high pressure phase containing water, monocarboxylic acid, unreacted substituted aromatic hydrocarbon, oxygen and the reaction by-products; and at least one purification step comprising contacting with hydrogen at elevated temperature and pressure in the presence of a catalyst comprising a metal hydrogenation catalyst, the reaction of the cleaning solution containing the liquid, consisting of water with the dissolved aromatic carboxylic acid and impurities separated from the reaction mixture of liquid-phase oxidation of at least one stage of liquid-phase oxidation, with the formation of the reaction mixture liquid-phase oxidation containing aromatic carboxylic acid and hydrogenated impurities dissolved in a liquid containing water; and at least one stage of separation of departing is it gas including the transfer of vapor phase high pressure discharged from the reaction section with at least one stage of liquid-phase oxidation in the partition dividing, where you can almost divide the solvent monocarboxylic acid, water and by-products of oxidation on the at least one liquid phase, enriched solvent monocarboxylic acid and at least one second liquid phase enriched water, and at least one second steam of the high pressure phase depleted in solvent monocarboxylic acid containing water vapor, so that the by-products of the oxidation of the original aromatic hydrocarbon preferably distributed in the first liquid phase, and side oxidation products of the solvent monocarboxylic acid is preferably distributed in the second vapor phase high pressure, and the removal of the partition separating the second liquid phase enriched water, which contains no solvent monocarboxylic acid and by-products of its oxidation, and a second vapor phase high pressure, which does not contain by-products of the oxidation of the original aromatic hydrocarbon; and at least one stage, comprising feeding a second liquid phase enriched water, which contains no solvent monocarboxylic acid and by-products of its oxidation, was to be played by the Oh of section separation comprising at least one off-gas phase separation at the stage of cleaning in the cleaning section, so that the liquid containing the water used by at least one stage of purification or isolation, separation or washing of the product is a liquid condensate.

Preferably, the stage of liquid-phase oxidation, purification and separation of the exhaust gas in this way according to variants of the invention have been integrated; the product of liquid-phase oxidation containing aromatic carboxylic acid and by-products and steam high pressure phase from a single act of the liquid-phase oxidation, is fed to the purification and separation of the exhaust gas, respectively, and a second liquid phase containing water (but not containing solvent monocarboxylic acid and by-products of its liquid-phase oxidation), isolated by separation of the exhaust gas is fed to the purification for use as a liquid containing water.

In another embodiment, the method according to this invention comprises the following steps: (a) contacting the feedstock containing an aromatic hydrocarbon is a precursor to aromatic carboxylic acid and gaseous oxygen in the reaction mixture of liquid-phase oxidation, containing the solvent monocarboxylic acid and water in the presence of a catalytic composition containing a heavy metal, in the section of the reaction at elevated temperature and allowing the attachment, sufficient to maintain a liquid reaction mixture and formation of aromatic carboxylic acid and impurities comprising by-products of the oxidation of substituted aromatic hydrocarbons which are dissolved or suspended in the reaction mixture of liquid-phase oxidation, and steam with high pressure phase containing the solvent monocarboxylic acid, water, by-products of the substituted aromatic hydrocarbon and by-products of the conversion of solvent monocarboxylic acid; (b) isolation from the reaction mixture of liquid-phase oxidation of solid product containing aromatic carboxylic acid and impurities comprising the reaction by-products; (C) the dissolution or suspension of the solid product isolated from the reaction mixture of liquid-phase oxidation, containing aromatic carboxylic acid and impurities, including by-products of the oxidation of substituted aromatic hydrocarbon, in a liquid containing water at least part of which is a second liquid phase, selected at stage (i) with the formation of the cleaning solution; (d) the contacting of the cleaning solution at an elevated temperature and pressure with hydrogen in the presence of a hydrogenation catalyst to form a liquid reaction mixture of cleaning; (e) the allocation of the liquid reaction mixture cleaning firm is th the pure product, containing aromatic carboxylic acid with a low concentration of impurities and a liquid mother liquor purification, containing water and small amounts of by-products of the oxidation source substituted aromatic hydrocarbons, hydrogenation products of their or their combinations; (f) feeding the vapor phase high-pressure stage (a), containing the solvent monocarboxylic acid, water vapor, by-products of the oxidation of substituted aromatic hydrocarbon and by-products of the conversion of solvent - carboxylic acid, irrigated by phlegm section separation, where you can split the solvent monocarboxylic acid, water and by-products at least one first liquid phase enriched solvent - carboxylic acid, and at least a second liquid phase enriched water, which is almost free of solvent monocarboxylic acid and at least one second steam of the high pressure phase depleted in solvent - carboxylic acid and containing water vapor, so that the by-products of the oxidation of substituted aromatic hydrocarbons are mainly in the first liquid phase and by the oxidation products of the solvent monocarboxylic acid - fall mainly into the second steam phase high pressure; (g) the selection of the section under the Oia separate threads of the first liquid phase, enriched solvent monocarboxylic acid, and a second liquid phase enriched water, which contains no solvent monocarboxylic acid and products of its oxidation, and the second steam of the high pressure phase, which contains almost no by-products of the oxidation of the original aromatic hydrocarbon; and (h) applying a second liquid phase enriched water, which contains no solvent monocarboxylic acid and products of its oxidation, abstracted from section separation stage (g), at least one of the stages (C), (d) or (e), so that the liquid containing water, at least one of the steps (C), (d) or (e) includes a second liquid phase.

In more specific embodiments, the liquid stream enriched solvent monocarboxylic acid, are served from a section of the separation section of the reaction. In other embodiments, cooling the second vapor phase high-pressure, water-containing virtually no by-products of the oxidation of the original aromatic hydrocarbon raw material for liquid-phase oxidation which take away from the section of the separation, leads to condensation with the separation of liquid condensate containing water, when the heat transfer from the second vapor phase to the heat exchanger with the formation of a stream or other heated liquid under pressure; the resulting flow or heated fluid under pressure mo is but to use for heating in other stages of the process. Alternatively, the second steam phase high pressure or a portion or exhaust the high pressure gas remaining after the condensation of the second vapor phase high pressure, can be processed at one or more stages of selection unreacted raw materials and solvents or by-products of the oxidation solvent utilization of energy by heat, for example by heat exchange, and utilization of energy by transformation into mechanical energy, for example, extender, or other suitable device, or combinations thereof.

Brief description of drawings

The invention is described with reference to the drawings, in which:

figure 1 is a block diagram of the apparatus and method according to preferred variants of the present invention, including the integration of the device in other equipment used for production and purification of aromatic carboxylic acids by the variants of the present invention; and

figure 2 gives an enlarged view of a preferred apparatus for the preferred variants of the invention and the method according to these options.

Detailed description

Aromatic carboxylic acids, which are applicable to this invention include mono - and polycarboxylate connection with one or more aromatic cycles, which can be obtained by using Rea is the gaseous or liquid reagents in liquid-phase system. Examples of such aromatic carboxylic acids include terephthalic acid, timesyou acid, trimellitic acid, phthalic acid, isophthalic acid, benzoic acid and naphthalenesulphonate acid. The invention is particularly suitable for the production of pure terephthalic acid and purified terephthalic acid and terephthalic acid so-called average purity.

Oxidation step of the proposed method is a liquid-phase oxidation, which comprises contacting the gaseous oxygen and feedstock containing an aromatic hydrocarbon substituents, are able to oxidize in the carboxylate groups in the reaction mixture of liquid-phase oxidation, containing the solvent monocarboxylic acid and water in the presence of a catalytic composition comprising at least one heavy metal. Stage oxidation is carried out at elevated temperature and pressure sufficient to maintain liquid reaction mixture and formation of the vapor phase at high temperature and high pressure. In the oxidation of aromatic raw materials at the stage of liquid-phase oxidation of the formed aromatic carboxylic acid, and the reaction by-products, such as products of incomplete oxidation or intermediate oxidation products of aromatic raw materials and solvent. Stage Jew who opasnogo oxidation and the associated stage of the process can be carried out at periodic, continuous or semi-continuous mode. Stage oxidation can be performed in one or more reactors.

Suitable aromatic raw materials for the oxidation include aromatic hydrocarbons, substituted in one or more positions, usually the relevant provisions of the carboxyl groups in the resulting aromatic carboxylic acid, if you keep at least one group that can oxidize in the carboxylate group. Oxidizable Deputy or deputies may be alkyl groups such as methyl, ethyl or isopropyl group, or groups containing oxygen, such as hydroxyalkyl, formyl or keto-group. The substituents may be the same or different. The aromatic part of the raw material may be benzene cycle or it can be bi - or political, such as naphthalene ring. The number of oxidizable substituents in the aromatic part of the raw materials may be equal to the number of centers available in the aromatic part, but it is usually less than the total number of centres, preferably 1-4 and most preferably 2. Examples of materials that can be used individually or in compositions, include toluene, ethylbenzene, and other alkyl substituted benzene, o-xylene, p-xylene, m-xylene, Truelove aldehydes, Truelove acid, alkylbenzene alcohols, 1-formyl-4-methylbenzol, 1-guide oxymethyl-4-methylbenzol, methylacetophenone, 1,2,4-trimethylbenzene, 1-formyl-2,4-xylene, 1,2,4,5-tetramethylbenzene, alkyl, formyl, acyl and hydroxymethylbilane naphthalenes, such as 2,6-dimethylnaphthalene, 2,6-deethylation, 2,7-dimethylnaphthalene, 2,7-deethylation, 2-formyl-6-methylnaphthalene, 2-acyl-6-methylnaphthalene, 2-methyl-6-ethylnaphthalene and not fully oxidized derivatives of such compounds.

For the production of aromatic carboxylic acids by oxidation of appropriately substituted the original aromatic hydrocarbons, for example for the production of benzoic acid from monosubstituted benzenes, terephthalic acid from para-substituted benzenes, phthalic acid from orthotamine benzene and 2,6 - or 2,7-naphthalenesulphonic acids from, respectively, 2,6 - and 2,7-disubstituted naftalina, it is preferable to use relatively pure raw materials and more preferably raw material containing a precursor of the desired acid number of at least about 95 wt.% and more preferably at least 98 wt.% and even more than. The preferred aromatic hydrocarbon for the production of terephthalic acid is para-xylene. The preferred raw material for the production of benzoic acid is toluene.

Solvent for liquid-phase reactions of transformation of aromatic raw materials in the aromatic carboxylic acid to study the liquid-phase oxidation is a low molecular weight monocarboxylic acid, preferably monocarboxylic acid C1-C8such as acetic acid, propionic acid, butyric acid, valeric acid and benzoic acid. Preferred lower monocarboxylic acid and benzoic acid, as they are less prone to the formation of unwanted products, the more high molecular weight monocarboxylic acid, in the reaction conditions used in liquid-phase oxidation of aromatic carboxylic acids, and can enhance the catalytic effects of oxidation. The most preferred acetic acid. In industry most commonly used solvents in the form of aqueous solutions, for example, about 80-95 wt.% acid solutions. Can be used with good results also ethanol and other solvents, which are oxidized under the reaction conditions of liquid-phase oxidation of monocarboxylic acids; they can be used in pure form or in combination with monocarboxylic acids. When using a solvent composed of a mixture of monocarboxylic acid and an additional solvent, it is preferable to use such additional solvents, which are oxidized in the same monocarboxylic acid, in order not to complicate the stage of separation of solvent.

As solvents for liquid-phase oxidation according to this invention, use is sovanna the expression "solvent - monocarboxylic acid" component for various gas or liquid flow refers to the monocarboxylic acid of the same chemical composition that the monocarboxylic acid used as a solvent in liquid-phase oxidation. This term helps to distinguish such chemical composition from other monocarboxylic acids, which may be by-products of oxidation. For example, using acetic acid as solvent in the liquid reaction mixture to oxidize the expression "solvent monocarboxylic acid" refers to acetic acid, but not to other monocarboxylic acids such as benzoic and tolarova acid, which are often by-products of incomplete oxidation or intermediate oxidation products used aromatic raw material. In addition, as will be clear from the context, the word "solvent" in the expression "solvent monocarboxylic acid" may include, but not necessarily, monocarboxylic acid, which is connected with it. Thus, again as an example, if the expression "solvent monocarboxylic acid" is used to describe a component of the reaction mixture liquid-phase oxidation, it refers to the solvent in the mixture; however, when using the expression "solvent monocarboxylic acid d the I component description steam high pressure phase, formed by oxidation, or a component of the liquid phase separated from such vapor phase, it does not mean that the monocarboxylic acid acts as a solvent.

The catalysts used in liquid-phase oxidation, include substances which are effective in the catalysis of the oxidation of aromatic raw materials in the aromatic carboxylic acid. Preferred catalysts are soluble in the liquid reaction mixture used for oxidation, because soluble catalysts promote the contact of the catalyst, gaseous oxygen and liquid raw materials; however, you can also use heterogeneous catalysts or components of the catalysts. Typically, the catalyst contains at least heavy metal, such as metal with an atomic weight in the range of about 23-178. Examples of heavy metals include cobalt, manganese, vanadium, molybdenum, chromium, iron, Nickel, zirconium, cerium or lanthanide type hafnium. Suitable compounds of these metals include, for example, acetates, hydroxides and carbonates. The preferred catalysts are cobalt, manganese, and combinations thereof and combinations with one or more other metals, especially hafnium, cerium and zirconium.

In preferred embodiments, the catalytic composition for liquid-phase oxidation also contain a promoter that increases the activity of catalyt the Cesky active metal in the oxidation preferably without the formation of undesirable types of products or their concentrations. To improve the interaction between the catalyst, the promoter and the reagents preferred promoters that are dissolved in the liquid reaction mixture used for oxidation. Usually as a promoter use compounds with Halogens, such as the hydrogen halides, the halides of sodium, ammonium halides, halogen-substituted hydrocarbons, halogen-substituted carboxylic acids and other halogenated compounds. Preferred promoters contain at least one source of bromine. Suitable sources of bromine include bromoanthracene, Br2, HBr, NaBr, KBr, NH4Br, benzylbromide, bromoxynil acid, tetrabromide, ethylenedibromide, bromoacetamide and combinations thereof. Other suitable promoters include aldehydes and ketones of the type of acetaldehyde and methyl ethyl ketone.

Reagents for liquid-phase reaction at the stage of oxidation also include a gas containing molecular oxygen. Traditionally as a source of oxygen using air. You can also use air, enriched with oxygen, pure oxygen and other gas mixture containing molecular oxygen, usually in concentrations of at least about 10 vol.%. As will be further emphasized, as the concentration of molecular oxygen in the source increases, reduced requirements for the compressor and operations with the trade is the principal gas in the exhaust gas from the reactor. When used in the way of air or oxygen-containing gas mixtures as a source of oxygen in the vapor phase high pressure formed in the liquid-phase reaction at the stage of oxidation, contains nitrogen or other inert gas components from a source of oxygen.

The ratio of aromatic raw materials, catalyst, oxygen and solvent are not critical to this invention and can vary depending on such factors as the choice of reactants, solvent and catalyst composition and the desired aromatic carboxylic acid, the features of the method and operating parameters. The preferred ratio of solvent and aromatic raw materials in the range of from about 1:1 to about 30:1, more preferred ratio is from about 2:1 to about 5:1, although it is possible to use higher and lower ratios even in the range of from one hundred to one. Gaseous oxygen is usually used in at least stoichiometric quantity per aromatic raw materials, but, taking into account the conditions of reaction speed and the organic components of the vapor phase of the high pressure formed in liquid-phase reactions, not in such great numbers that in the vapor phase formed combustible mixture. In the industry when using the preferred aromatic what about the raw materials, the solvent monocarboxylic acid, the catalytic compositions and operating parameters of gaseous oxygen, is most often applied to liquid-phase oxidation in air, it is preferable to apply for liquid-phase oxidation at a speed effective to achieve a ratio of at least about 3-5 .6 moles of molecular oxygen per mole of aromatic hydrocarbon in the feedstock. Vapour phase high pressure generated in the liquid-phase oxidation, it is preferable to withdraw from the reaction with such speed that the oxygen concentration in the vapor phase in the reaction section was approximately 0.5-8% vol. oxygen in the calculation of the base without solvent. Ceteris paribus variations in the oxygen content in the vapor phase, for example, by increasing or decreasing the speed of reaction resulting from the use of larger or smaller quantities of catalyst in liquid-phase oxidation can affect the formation of by-products of oxidation, and at a lower oxygen content in the vapor phase, for example to about 3 vol.% or about 0.5-2.5%vol., there is a tendency to a more complete conversion of the feedstock aromatic hydrocarbon - aromatic carboxylic acid, and, on the other hand, to reduced formation of by-products of the oxidation of aromatic raw materials, but increased formation of side products is tov oxidation of the solvent. For example, in liquid-phase oxidation of para-xylene in acetic acid as solvent oxidation preferred vapor phase with a content of about 0.5 to 3% vol. oxygen to obtain an aromatic carboxylic acid with a low concentration of by-products of the oxidation of para-xylene and high concentration of by-products of the oxidation of acetic acid compared with operation at higher oxygen concentration in the vapor phase. Usually, a catalyst concentration of metal based on the weight of the aromatic hydrocarbon and the solvent is more than about 100 ppm by weight, preferably more than about 500 ppm by weight and less than about 10,000 ppm by weight, preferably less than about 6000 ppm by weight, more preferably less than about 3000 ppm by weight. Preferably, attended halogen promoter, and more preferably the promoter containing bromine. Such a promoter is present in an amount such that the atomic ratio of halogen and a catalytically active metal was more than about 0.1:1, more preferably about 0.2:1 and less than about 4:1, preferably less than about 3:1. Most preferably, when the atomic ratio of halogen and a catalytically active metal varies from about 0.25:1 to about 2:1. Under other equal conditions the expansion of the m concentration of catalyst in the reaction mixture, the oxidation reaction rate and the absorption of gaseous oxygen in liquid-phase oxidation and increase the concentration of unreacted oxygen in the vapor phase process oxidation is reduced.

Liquid-phase oxidation reaction of aromatic raw materials in a product containing an aromatic carboxylic acid is carried out in the corresponding section of the oxidation, which usually includes one or more reaction vessels oxidation. Suitable reaction vessels oxidation is designed in such a way that they withstand high temperature and pressure and used corrosive liquid and vapor phase in the reaction section, so you can add and mix the catalyst, liquid or gaseous reagents and solvent, to remove the formed aromatic carboxylic acid, or a liquid containing such a product, to highlight and delete steam high pressure phase formed in the liquid-phase reaction, to control the heat of reaction. The reactors which are suitable for use include reactors periodic action with a stirrer and a flow reactors ideal displacement. Typically, the oxidation reactors are in the form of a column, usually with a Central axis, which in the vessel for carrying out the process is held vertically, with one or more device for mixing liquid reagents and distribution of gaseous oxygen in a liquid boiling of the reaction mixture. Normally device for mixing include one or more blades on BP is mausima or otherwise moving the rod. For example, the blades may be directed away from the Central vertical rotating rod. The reactors can be made from materials designed to operate at specific temperatures and pressures and the use of these reagents. Typically, the oxidation reactors are made of corrosion-resistant materials such as titanium, or at least cover such materials on their surface, bounding the internal space or volume that contains the liquid reaction mixture and the exhaust gas of the reaction, for example, lined with such materials as titanium or glass.

The reaction mixture for liquid-phase oxidation is formed by combining components comprising aromatic raw materials, solvent and catalyst, and feeding the mixture of gaseous oxygen. In continuous or semi-continuous methods, it is preferable to combine them in one or more vessels for mixing prior to submission to the oxidation section; however, the reaction mixture can be prepared in the oxidation section. The source of gaseous oxygen can be introduced into the reactor at one or more points, and usually it is served in such a way as to make contact between molecular oxygen and other reagents, for example, by compressed air or other source of gaseous oxygen in the liquid portions, the volume of which is less than or intermediate with respect to the internal capacity of the reaction vessel.

Oxidation of an aromatic feedstock to aromatic carboxylic acid is carried out in conditions of oxidation reactions that maintain the reaction mixture in the liquid state and the formation of aromatic carboxylic acid and impurities, which represent by-products of the oxidation of aromatic hydrocarbons which are dissolved or suspended in the liquid reaction mixture, and the formation of high temperature vapor phase high-pressure gaseous components which mainly consists of the solvent monocarboxylic acid (e.g. acetic acid, when the solvent of the oxidation reaction contains acetic acid and water and small amounts of by-products of the oxidation of the solvent monocarboxylic acid, such as lower alcohols and esters solvent - monocarboxylic acid (for example, methanol and methyl acetate, when the solvent contains acetic acid) - and by-products of the oxidation of the raw material aromatic hydrocarbon, such as products of incomplete oxidation and intermediate oxidation products (e.g., benzoic acid and p-tolarova acid, when the material is para-xylene). The content of by-products of oxidation in the vapor phase is typically about 0.5-2 wt.%. The concentration of by-products of the oxidation of the initial aroma is of glendorado usually be about 0.01-0.05 wt.%. Steam high pressure phase also typically contains unreacted aromatic feedstock and gaseous oxygen, which is included in the vapor phase. When using air, which is commonly practised in industry, or other sources of oxygen gas containing nitrogen or other inert gas components, the vapor phase will also contain these inert components. Generated during the oxidation of the heat is dissipated by boiling the liquid reaction mixture and extraction steam phase of the upper ring section of the response.

Usually the temperature of the liquid phase of the reaction is maintained at about 120°C. or higher and preferably about 140°C or above but below about 250°C. and preferably below about 230°C. To obtain such aromatic carboxylic acids as terephthalic acid, benzoic acid and natalijagolosova acid, the preferred reaction temperature in the range of about 145°C. - 230°C. At temperatures below about 120°C liquid-phase oxidation can proceed with uneconomic rates, or conversions, which can adversely affect the quality of the product. For example, the production of terephthalic acid from para-xylene at a temperature below about 120°C. may take more than 24 hours to complete and the resulting terephthalic acid may need to be on the additional processing due to the presence of impurities. Temperatures above about 250°C. are undesirable because of the possibility of fire and loss of solvent. To control the temperature of the boiling liquid reaction mixture pressure can be used, which is chosen so that basically keep the reaction mixture in the liquid state. Preferred is a pressure of about 5-40 kg/cm2despite the fact that the preferred pressure for a particular process depends on the composition of the feedstock and solvent, temperature, and other factors, and more preferably is in the range of about 10-30 kg/cm2. When the pressure of the reaction approximately 7-21 kg/cm2the temperature of the reaction mixture containing the solvent of acetic acid, and the vapor phase formed during liquid-phase reaction, approximately 170-210°C. the contact Time in the reaction vessel may be different depending on performance and conditions, accounting for approximately 20-150 min for a number of processes. In the production of some aromatic carboxylic acids, such as terephthalic acid from para-xylene, using acetic acid as solvent for the reaction mixture solids content in the boiling liquid reaction mixture can be up to about 50 wt.% the liquid reaction mixture, usually about 10-35 wt.%. In the case when the obtained aromatic acid Rast is areeda in the reaction solvent, the concentration of solids in the liquid volume is negligible. As will be obvious to experts in the field of manufacture of aromatic carboxylic acids, preferred conditions and operating parameters will vary depending on the composition of different products and methods and can be in the above intervals and even go beyond them.

The reaction products of liquid-phase oxidation include aromatic carboxylic acid obtained by the oxidation of aromatic raw materials, impurities as by - products of liquid-phase reactions and, as noted above, the steam of the high pressure phase, the resulting liquid-phase reactions, including the boiling liquid reaction mixture, to remove the vapor phase to control the reaction temperature. Specific examples of by-products of the oxidation of aromatic raw materials include products of incomplete oxidation or intermediate oxidation products, such as toluylene acid, Truelove aldehydes, carboxybenzaldehydes and hydroxymethylbenzene acid. By-products of liquid-phase reactions also include the products of transformations solvent, such as methanol and other lower aliphatic alcohols, formed by the oxidation of the solvent of the reaction mixture, and esters formed by the reaction of these alcohols with solvent, primarysecondary are methyl acetate, methylpropionate, methylbutyrate etc.

By-products are usually present only in the liquid oxidation reaction mixture or in the liquid and steam phases. Carbon dioxide as by-products can be formed during the oxidation of the solvent, raw materials or by-products of their oxidation. In those embodiments of the invention, in which liquid-phase reaction is carried out using a source of bromine as a promoter, by-products usually contain lower were synthesized, for example methyl bromide, when the reaction solvent is acetic acid, which is usually formed by the reaction of bromide ion with acetic acid. As described above, formed in the reaction of brominated by-products and impurities may be present only in the liquid reaction mixture or in the liquid phase and in the vapor phase high pressure. In some embodiments of the method proposed, for example in the case when the solid product liquid-phase oxidation clear and the mother liquor or other threads recycling containing liquid phase purification or their components, are served directly or indirectly on the liquid-phase oxidation or separation off-gas as phlegmy, other by-products, such as benzoic acid and Truelove acid transferred in the composition of the cleaning liquid and hydrogenated made in the various derivative products, formed on the stages of purification, and unreacted aromatic hydrocarbon, aimed at cleaning up, can also be fed into the reaction mixture of liquid-phase oxidation in the exhaust gases.

Water is also formed at the stage of oxidation as a by-product of liquid-phase oxidation. However, since the water can also be added to the liquid reaction mixture, for example, using an aqueous solution of solvent monocarboxylic acid or streams of recycling with other stages of the process, and also due to the significant quantities of water under oxidation or as a by-product, or added specifically, and due to the fact that it is impossible or there is no need to distinguish between the water of reaction and water, added specifically used here, the expression "by-products of liquid-phase reactions" and similar expressions do not apply to water, unless otherwise noted. Similarly, when water or water vapor is described here as components of various liquids, gases or streams, no matter whether the water byproduct of the liquid-phase oxidation, whether it's been in process specially, or both, unless otherwise stated or is evident from the context.

The obtained aromatic carboxylic acid, suspended or dissolved in part of the liquid reaction mixture of liquid-phase oxidation, it is possible clicks in order to work through any suitable techniques for separation therein of the obtained aromatic carboxylic acid. Usually obtained aromatic carboxylic acid and by-products of the oxidation of aromatic raw materials, suspended, or dissolved and suspended and dissolved in the liquid reaction mixture is withdrawn from the reaction section for liquid-phase reactions and produce with the help of suitable methods. Thus, the liquid-phase oxidation according to the proposed method may include, in addition to the oxidation of the extraction of the liquid reaction mixture, the oxidation product of an aromatic carboxylic acid and impurities, representing the reaction by-products. It is preferable to select the product in the form of solids.

Dissolved in the liquid product can be distinguished by crystallization, which is usually carried out by cooling and pressure relief above suspension in a liquid or in solution, taken from the section of the oxidation reaction. The solid product suspended in liquids, and solids, vegascasinoonline from the reaction liquid or solvent crystallization, traditionally separated from the liquid by centrifugation, filtration or a combination of these methods. Solid products isolated from the reaction liquids such methods include aromatic carboxylic acid and impurities containing by-products of the oxidation of aromatic raw materials. The liquid remaining is jaś after separation of the solid product from the liquid reaction mixture, also called mother liquor of oxidation, contains solvent monocarboxylic acid and water, the catalyst and the promoter, the soluble by-products of liquid-phase oxidation and impurities that may get out threads recycling. Usually the mother liquor also contains small amounts of aromatic carboxylic acids and the products of incomplete oxidation and intermediate oxidation products of aromatic raw materials, the remaining unselected from the liquid. It is preferable to return at least a portion of the mother liquor in the reaction section at least one cycle of liquid-phase oxidation, so that the components involved in liquid-phase reactions, such as catalyst, promoter, solvent and by-products into the desired aromatic carboxylic acid can be reused.

In preferred embodiments of the present invention, the liquid reaction mixture in the oxidation containing aromatic carboxylic acid and by-products of liquid-phase oxidation reaction, are separated from the liquid solidification on one or more stages, i.e. in a single crystallization vessel or series of vessels crystallization with a sequential decrease of temperature and pressure from the initial to the subsequent stages to increase the level of separation of the product. Crystallization in two-even the re stage, for example, the temperature of the oxidation reaction in the range of about 140-250°C and a pressure in the range of about 5-40 kg/cm2to the final crystallization temperature in the range of about 110-150°C and pressure from normal to about 3 kg/cm2leads to almost complete crystallization of solid aromatic acid. The mother liquor separated from the solid product by crystallization, can be returned to liquid-phase reaction, as described above. Heat away from the vessels crystallization by selecting the gas phase resulting from boiling of the reaction liquid or another way to reduce pressure, and preferably by condensation of the vapor phase with one or more stages and return directly or indirectly through one or more additional stages of separation, as discussed below, at least partially in section of the reaction for use in liquid-phase oxidation.

The solid product selected after liquid-phase oxidation, typically contains an aromatic carboxylic acid and impurities, which represents an intermediate oxidation products of aromatic raw materials, can be separated from the mother liquor of oxidation, formed after separation of the solid product, in whatever way is appropriate. Examples include centrifugation, vacuum filtration and the filter using a belt filter, the RC. The obtained solid product is preferably washed after separation of the liquid containing water, such as pure water or rinsing liquid containing a small amount of solvent monocarboxylic acid and catalyst, aromatic raw materials, corrosion products, or their combination, which is better to return in the oxidation process, either directly or together with other liquids, such as the mother liquor of oxidation or other fluid that is returned to the reaction section. The separation of the solid crude aromatic carboxylic acid selected from the mother liquor of oxidation and leaching of the solid product has traditionally carried out by filtration under pressure with the replacement solvent, using a press-filters disclosed in U.S. patent 5679846 and 5200557. The preferred device for filtering is a BHS-Fest filter, more fully described in U.S. patent 5200557. The mother liquor and the washing liquid after separation of the precipitate on the filter can be submitted directly or indirectly on the liquid-phase oxidation. Multi-stage filtration and washing of the solid product all over the net leaching liquids, such as liquids after separation of the precipitate on the filter at a later stage compared with liquids from the early stages of leaching, especially useful due to the concentration of solvent - monocarb the OIC acid, displaced from the solid on the filter and returned to the oxidation. In a more specific embodiment, the filter cake is soaked in the liquid obtained after the filtration, served with end-stage leaching on the stage of drying, in which it is in contact with the inert gas is usually at low or medium pressure to remove the main part of the remaining liquid from the precipitate on the filter. After washing and removing the bulk of the wash liquid from the solid product containing aromatic acid and by-products obtained solid substance can be dried and sent to storage or to other stages, which may include the preparation of reaction solution for the treatment of solid product. Preferably, the concentration of residual solvent monocarboxylic acid in the solid product applied to clean, amounted to about 5000 parts per million by weight ("ppm by mass") or less. To reduce the concentration of residual solvent, the solid product can be dried in a stream of nitrogen or other inert gas.

Along with the product liquid-phase reaction phase oxidation of aromatic carboxylic acid in the present invention is formed steam high pressure phase containing the solvent monocarboxylic acid, water and by-products of liquid-phase oxide is to be placed, as explained above. Usually the vapor phase contains a small amount of unreacted aromatic raw materials, unspent oxygen or possibly inert components from a source of oxygen. The temperature and pressure of the vapor phase in the reaction section, comply with the terms of liquid-phase reactions. Separation of exhaust gas according to this invention allows to distinguish substances and in some embodiments, energy, and combinations thereof from the exhaust gas with high temperature and high pressure discharged from the liquid-phase oxidation reaction.

Separation of exhaust gas according to the present invention involves feeding the vapor phase withdrawn from the reaction section of liquid-phase oxidation in the partition dividing, where you can almost divide the solvent monocarboxylic acid, water and by-products of the oxidation of at least one first liquid phase enriched solvent monocarboxylic acid and at least one second liquid phase enriched water, which is almost free of solvent monocarboxylic acid and at least one second steam of the high pressure phase depleted in solvent monocarboxylic acid and containing water vapor, so that the by-products of the oxidation of the original aromatic hydrocarbon preferably get the first liquid phase and by-products of the oxidation solvent - monocarboxylic acid is preferably belong to the second steam of the high pressure phase. From section division assign the first liquid phase enriched solvent monocarboxylic acid and a second liquid phase enriched water, which is almost free of solvent monocarboxylic acid and by-products of its oxidation, and a second steam of the high pressure phase, which contains almost no by-products of the oxidation of the original aromatic hydrocarbon. The separation of the vapor phase high pressure is carried out at a temperature and pressure which are not lower than the temperature and pressure vapor phase at the stage of liquid-phase oxidation, which leaves the vapor phase.

In more detail, the separation involves feeding the vapor phase high pressure at high temperature, abstracted from the reaction vessel liquid-phase oxidation, in section separation, where you can work with a steam phase at high temperature and pressure for a real separation of water and solvent monocarboxylic acid in the vapor phase and distribution of by-products of oxidation between the liquid and gaseous phase resulting from the separation, so that the content of by-products of the oxidation of the solvent in the liquid phase and by-products of the oxidation of aromatic hydrocarbons in the gas the phases, selected after separation, was minimal. Steam high pressure phase fashionable to submit sections of the reaction section division directly, when a device for the separation is mounted on the reaction vessel oxidation or very close to it, or from another section of the oxidation, or indirectly, for example by means of suitable pipes, valves, pumps, etc. for effective transfer. A small portion of the vapor phase high pressure and at high temperature of the section of the liquid-phase oxidation can be used for other purposes, such as generating a stream of high pressure or liquid coolant to the heat exchanger. Preferably, the vapor phase, submitted to the division, remained at a sufficiently high temperature and pressure, the energy of the vapor phase entering the section of split, at least practically remained in the vapor phase was carrying a sufficient amount of heat to separate in contact with phlegm, supplied in section separation. It is most preferable to transfer the vapor phase section of the division directly from the reaction section or through the piping system at a suitable pressure, so that the temperature of the vapor phase entering the section of the separation was lower by no more than about 10°C. the reaction temperature liquid-phase oxidation and the pressure of the steam the basics, coming into the section of the separation was below the pressure of liquid-phase oxidation of no more than about 3 kg/cm2. Section division also adapted for operation at high temperature and pressure and preferably at temperatures and pressures generally not lower than the temperature and pressure steam high pressure phase in the reaction section, in order to avoid energy losses in vapor phase from the reaction section. More preferably, the section of the separation was designed for processing vapor phase under pressure, comprising at least about 80%, more preferably at least about 90% and even more preferably at least about 95% of the pressure of the steam phase at the stage of oxidation. Allowable pressure for equipment in section separation should preferably be at least about 80%, more preferably about 90-110% of the allowable pressure in the reaction vessel oxidation or partition oxidation steps in the proposed method, from which the steam phase serves for separation. Preferably, the temperature of the vapor phase section of the division was in the range of about 140-200°C., and more preferably about 160-185°C. the Preferred pressure is approximately 5-40 kg/cm2and the most preferred pressure is equal to 10-20 kg/cm2

In section separation can be almost completely separated, the solvent monocarboxylic acid and water vapor in the vapor phase high-pressure, submitted to the division. Preferably, in the section of the separation was the possibility of separating water and solvent in the vapor phase high pressure so that the high-pressure gas generated during the separation, contained no more than about 5% of the content of the solvent monocarboxylic acid in the vapor phase is supplied to the section separation. More preferably, the content of the solvent monocarboxylic acid in the second exhaust gas of a high pressure after splitting does not exceed approximately 2%, and even more preferably it does not exceed about 1% of the content of the solvent monocarboxylic acid in the vapor phase is supplied to the section separation. Section separation must also be adapted to the preferred distribution of by-products of the oxidation of an aromatic feedstock with at least one liquid phase and by-products of the oxidation of the solvent monocarboxylic acid, a second steam of the high pressure phase, which otherwise at temperatures and pressures at which carry out the separation, usually fall in steam, in the liquid phase. For example, in the case of liquid-phase oxidation of para-xylene as with the earth with the total amount in the liquid-phase reaction mixture, solvent is acetic acid, the by-products of the oxidation of para-xylene - benzoic acid and p-tolarova acid and by-products of the oxidation of acetic acid - methanol and methyl acetate can be distributed in appreciable concentrations between steam and liquid phases. In section separation can be distributed by-products so that the second vapor phase high pressure will not contain by-products of the oxidation of the original aromatic hydrocarbon and preferably will contain them in an amount not more than about 10 wt.% and more preferably about 1-5 wt.%. By-products of the oxidation of the original aromatic hydrocarbon selected in the first liquid phase enriched solvent monocarboxylic acid and a second liquid phase enriched water, preferably distributed in the first phase and more preferably such that from about 75 wt.%, even more preferably at least about 85 wt.% to about 100 wt.% was in the first liquid phase and no more than about 25 wt.%, even more preferably no more than about 2-10 wt.% were in the second liquid phase. Side oxidation products of the solvent monocarboxylic acid containing alcohols and esters solvent, preferably belong to the second steam the ABC high pressure, formed after the separation of water and solvent monocarboxylic acid is supplied in the vapor phase high pressure, preferably so that the second enriched water liquid phase does not contain more than about 10 wt.% and more preferably no more than about 1-4 wt.% such products.

Partition separating the exhaust gas according to this invention may include any device for the almost complete separation of the solvent monocarboxylic acid and water in the vapor phase high pressure and at high temperature allotted after liquid-phase oxidation, and distribution of by-products of oxidation in the device at high temperature and pressure to obtain a liquid phase rich in solvent monocarboxylic acid, a second liquid phase enriched water, and the second steam high pressure phase containing water as described above.

In one preferred embodiment, the partition separating adapted for contact between the vapor and liquid phlegm, flowing counter-current, so that the solvent monocarboxylic acid in the vapor phase high-pressure, supplied in a section separate from the section of liquid-phase reactions, virtually transferred from the vapor phase into the liquid phase with the formation of the first liquid phase enriched solvent is monocarbonate acid, when that water is formed from the vapor phase high-pressure - depleted solvent monocarboxylic acid, is transferred into the liquid phlegm removal of the partition separating the second liquid phase enriched water. By-products of the oxidation of aromatic raw materials by way of liquid-phase oxidation, which in terms of division tend to be apportioned between the steam and liquid phases are present in the vapor phase high-pressure, supplied to the section after separation of liquid-phase oxidation, and they can also enter in section separation together with supplied by phlegm. Such side products in the liquid phase, which is carried by the solvent monocarboxylic acid from the vapor phase high pressure, can be removed in the first liquid phase. The by-products are in the vapor phase depleted in solvent monocarboxylic acid, and then fall into this liquid phase and enter the liquid phase, in which water is transferred from the vapor phase depleted in solvent, as a result of contact with liquid phlegm. Side oxidation products of the solvent monocarboxylic acid, which can be distributed between the steam and liquid phases may be present in the vapor phase high pressure after oxidation, supplied in section separation. They can also paragraph shall be in the phlegm, supplied in section separation. Such side products in the liquid phlegm separation devices, removes the phlegm from the vapor phase.

Flow phlegmy in such a device for the separation contains liquid components removed or dispensed from the vapor phase into the liquid phase, as well as components of liquid phlegmy supplied to the section of the distribution that are present or remain in the liquid phase.

The preferred section is split according to a more specific variant of the invention involves sequential contacting between the liquid and vapor phases in countercurrent through the part or area of the section of the separation. Preferably, the flow of the vapor phase through the end of section division was rising, and the flow of the liquid phase is downward. Separation of water and solvent monocarboxylic acid and by-products is carried out, feeding steam to the high pressure phase selected from the reaction section, in the first part of the section, division, and the phlegm in the third part of the section separation, so that the flow of the vapor phase through the first part to the second part and then to the third part of the section division is in contact with the countercurrent liquid phlegmy through the third to the second and to the first part of the section separation. Phlegm supplied to the third part contains water and preferably contains no by-products of oxidation aromaticheskogo the raw material liquid-phase oxidation. Water and solvent monocarboxylic acid - current counter-current vapor phase and in the liquid phlegm almost share in the first part, and the formation of the first liquid phase enriched solvent monocarboxylic acid, and an intermediate steam high pressure phase depleted in solvent monocarboxylic acid. The first liquid phase enriched solvent from the first part collected for removal of the section of the separation. The flow of the vapor phase from the first to the second part of the device for separating includes an intermediate steam phase from the first part. Water and by-products in the countercurrent vapor phase and phlegmy second parts, so that by-products of the oxidation of the original aromatic hydrocarbon selected in the phlegm and forms the second intermediate steam high pressure phase containing water vapor, practically free of solvent monocarboxylic acid and by-products of the oxidation of the original aromatic hydrocarbon. The flow of the vapor phase from the second to the third part of section division includes a second intermediate steam phase. Water and by-products of the oxidation of the solvent monocarboxylic acid in countercurrent vapor phase and phlegmy in the third parts, so that the formed second liquid phase enriched in water and practically no aderasa the solvent - monocarboxylic acid and by-products of its oxidation, and a second steam of the high pressure phase, containing water vapor and by-products of the oxidation of the solvent monocarboxylic acid and containing no by-products of the oxidation of the original aromatic hydrocarbon. The second liquid phase enriched water from the third part collected for removal from the device for separating liquid stream separately from the stream, which removes the first liquid phase. The second steam of the high pressure phase is removed from the device for separation in the form of exhaust gas. Flow phlegmy through a section of the separation, you can Deposit an additional amount of phlegmy containing water, in one or more sections of the division. In preferred embodiments, the liquid containing water serves as an extra phlegm between the second and third parts of this section of the separation.

At this stage the separation in the first part of section division you can divide the solvent monocarboxylic acid and water in such a way that at least 95 wt.% and more preferably at least about 98 wt.% the solvent is removed in the first liquid phase. Preferably, the second part can be spread by-products of liquid-phase oxidation of aromatic hydrocarbons between the first and second liquid the phases thus to the second vapor phase high pressure contained no more than about 10%, and more preferably about 1-5% of the amount of such by-products contained in the first and second liquid phase and a second vapor phase high pressure. Preferably, in the third part can be spread by-products of liquid-phase oxidation of solvent monocarboxylic acid in the second steam phase high pressure, so that the second liquid phase does not contain more than about 10%, and more preferably about 1-4% of the number of such products that are in the first and second liquid phase and a second vapor phase high pressure.

In preferred embodiments, the first part of the section separation is defined as the area section division located between the steam inlet of the high pressure phase after liquid-phase oxidation in the section of the separation and the entrance of fluid, containing water, in section separation as phlegmy. The second part of the section separation is defined as the area of the section located between the inlet fluid containing water, as phlegmy in the first part and the output of the removed second liquid phase enriched in water collected from the third part. The third part is defined as the area between the output of the removed second liquid phase enriched in water collected from the third part,and the entrance of the liquid, containing water and containing no by-products of the oxidation of aromatic raw materials of liquid-phase oxidation, in a device for the separation.

According to variants of the present invention, the section of the separation, in which there is a division and a preferred distribution of water, solvent monocarboxylic acid and by-products, includes a section of a fractionating at least about 20 theoretical equilibrium stages for the almost complete separation of water and solvent monocarboxylic acid in a pair of high pressure after the liquid-phase oxidation. More preferably, such a fractionation section consisted of approximately 20-60 theoretical equilibrium stages. For the separation of water and by-products of the oxidation of aromatic raw materials of the preferred fractionation section at least approximately 2 theoretical equilibrium stages. More preferably, the fractionation section consisted of approximately 2-10 theoretical equilibrium stages. Preferably, the section of fractionation for the separation of water and by-products of the oxidation of the solvent monocarboxylic acid containing at least one and more preferably about 1-10 theoretical equilibrium stages.

The preferred device for separating represent the th different columns or towers, often referred to as distillation columns and towers, towers dehydration, distillation columns, columns removal of water and the high efficiency separation device, which is intended for contact of flowing gas and liquid phases, mass transfer between phases in the majority of theoretical equilibrium stages, sometimes also called "theoretical plate"designed to separate and preferred distribution of the flow components of the gas and liquid phases. The contact between the threads of the gas and liquid phases is provided with internal structure, such as a plate and the gasket, forming a contact surface gas-liquid and theoretical equilibrium stage separation. The temperature of the vapor phase high pressure removed after oxidation, usually quite high, so there is no need for boiling the addition reaction of liquid-phase oxidation. The countercurrent gas and liquid phases, for example, when applying steam with high pressure phase after oxidation in the lower part of the device and phlegmy at least one and preferably two or more of the upper parts is preferred to ensure contact between the gas and liquid phases in the separation device.

Section separation according to this invention may contain one device the creation or sequentially located several devices, such as towers, columns, or other devices. When using two or more series-connected devices corresponding inputs and outputs have in them so that vapor phase high pressure discharged from the reaction vessel oxidation, moved on devices division and distribution of the solvent monocarboxylic acid, water and by-products of oxidation in series along the steam flow and the reverse flow phlegmy.

Phlegm supplied in section separation, contains water. You can use any source of liquid containing water and containing no impurities that adversely affect the separation. You can use demineralized water or other purified sources, but preferred sources contain liquid condensate high pressure gases discharged from sections of division and/or condensation of the proposed method. In another preferred embodiment, the mother liquor phase, obtained by selection of the purified aromatic carboxylic acid of at least one liquid reaction mixture is fed to the separation, with phlegm contains the mother liquor phase. Most preferably, the phlegm to separate contained the mother liquor phase and a water-containing liquid condensed from the gases high giving is to be placed, removed from a section of the separation, which can be submitted to the division alone or in combination with one or more separate threads.

When stepwise separation according to preferred variants of the present invention, as described above, the phlegm containing mother liquor cleanup phase, is fed into the section of the division for the flow components of the liquid phase through the second part of the section, and the liquid condensate is separated from the second vapor phase high pressure serves to flow through the third part. The mother liquor cleanup phase usually contains by-products of the oxidation of aromatic raw materials in the method of liquid-phase oxidation, including their hydrogenated derivatives, formed at the stage of purification, but such by-products are preferably distributed in a liquid phase, allocated in the division, and almost the first liquid phase enriched solvent monocarboxylic acid, which is suitable for return to the process of oxidation of the solvent. A liquid containing water, condensed from the second vapor phase high-pressure, abstracted from section separation, contains almost no by-products of the oxidation of aromatic raw materials, but may contain by-products of the oxidation of the solvent monocarboxylic acid, caught the second steam phase high pressure the Oia at division, which, in turn, can be present in the water-containing liquid condensed from the second high pressure gas. Such side products returned separation in the liquid phlegm supplied to the third part of the section of the separation, the separation desorbers back to the second steam of the high pressure phase. In preferred embodiments of the invention the undesirable accumulation of such products prevent such a manner that a portion of the liquid condensate is separated from the second vapor phase high pressure separation, purge or sent for processing to select such products.

It is preferable to apply a liquid phlegm with such speed and at such temperature that is effective enough to remove the heat of reaction of liquid-phase oxidation, the incoming section of the division together with the vapor phase after oxidation. In the case when the section division is connected with the reaction vessel liquid-phase oxidation for almost a direct feed vapor phase from the reaction of oxidation of separation, the reaction vessel acts as a reboiler. In such embodiments, the feed speed of phlegmy in section separation is traditionally expressed as the mass of the fluid supplied to the section divided by the weight of the aromatic raw material supplied to the liquid-phase oxidation. Preferably, ctabitem, supplied in section separation in the proposed version, was at a temperature in the range of about 120-170°C., and more preferably about 130-160°C. At these temperatures the liquid is supplied to the separation at a rate of approximately 4-5 mass of liquid per mass of aromatic hydrocarbon supplied to the liquid-phase oxidation. In the case when the liquid phlegm served in the partition separating separately at a different stage, it is distributed between different stages so that the supply phlegmy to the first stage section of the division was at least 40% and more preferably about 60-90% of the volume flow phlegmy.

Water vapor and solvent contained in the flow of high-pressure steam discharged from the stage of liquid-phase oxidation and supplied to the section division is divided in such a way that highlights the first liquid phase enriched solvent monocarboxylic acid - depleted water. Preferably, the separated first liquid phase contains at least about 60 wt.% the solvent monocarboxylic acid and not more than about 35 wt.% water. More preferably, the water content of the separated liquid phase was about 15-30 wt.%. The liquid stream after separation contains a small amount of heavier impurities, such as intermediate and by-products of oxidation and matichenkov raw materials and their hydrogenated derivatives, for example benzoic acid, and depending on the aromatic hydrocarbon used in the oxidation of m-Truelove acid and/or p-Truelove acid, washed or moved into the first liquid phase section of the division. The first liquid phase may also include other components, such as obtained aromatic carboxylic acid and a catalytically active metals. The content of such heavier components can reach up to about 2 wt.%, but preferably it does not exceed about 0.5 wt.%.

The liquid phase, enriched solvent monocarboxylic acid and condensed from the vapor phase section of the separation represents a valuable source of solvent for liquid-phase oxidation. As described above, it may also include by-products of the oxidation of aromatic raw materials and other components suitable for return to the oxidation and conversion into the desired aromatic carboxylic acid. Other useful directions for the use of liquid condensate include washing fluid for rotary vacuum filters or other devices for the separation of solids and liquid in the selection of solid products, liquid-phase oxidation of mother solutions phase oxidation or solvents of crystallization for scrubbers, such as scrubbers, dehydration, if they are used with the person. In a preferred embodiment of the proposed method at least part and preferably all or substantially all of the separated first liquid phase selected from section separation, returns to liquid-phase oxidation or directly in the reaction vessel or replacement vessel that is used for feeding the solvent in the reaction section. In such embodiments, it is preferable to divide the water and solvent monocarboxylic acid in the vapor phase high-pressure, supplied to the section separation to liquid phase obtained in the separation, he was held for about 15-30 wt.%, and more preferably, the water content of the separated liquid along with water that is returned to the oxidation of other liquid flows way, almost balanced amount of water vapour allotted after oxidation in the upper chase vapor phase high-pressure liquid water allotted after oxidation for isolation and separation obtained in the oxidation of aromatic carboxylic acids.

The second liquid phase that is selected with the separation of the enriched water and contains almost no side oxidation products of the solvent monocarboxylic acid - stage liquid-phase oxidation. It can contain small amounts of by-products of the oxidation of aromatic raw materials of liquid-phase oxidation in d is the query result of the preferential distribution of such products in the liquid phase in the separation according to this invention. The content of the solvent monocarboxylic acid in the second liquid phase is typically less than about 5 wt.% and preferably approximately1/2-3 wt.%. The byproducts of the oxidation of the solvent is usually not more than about 1 wt.% and preferably is about 0.05-0.2 wt.%. By-products of the oxidation of aromatic raw material in the second liquid phase is usually contained in an amount of about 0.003 to 0.1 wt.% and preferably about 0.005-0.05 wt.%. This fluid is suitable for use as a liquid containing water, one or more stages of method of purification unpurified forms of aromatic carboxylic acids, as described herein. Other applications of the second liquid phase include locking fluid for separation of solids and liquids used to separate the mother liquor of the oxidation method and the wash liquids from crude solid aromatic carboxylic acid selected from the reaction mixture of liquid-phase oxidation.

The second high-pressure gas generated during the separation, contains appreciable amounts of water and almost free of solvent monocarboxylic acid. Preferably, the gas contains at least about 55% vol. and more preferably at least about 65% water. The content of the solvent monocarboxylic sour the s - in the gas is usually less than about 5 and preferably less than about 3 wt.%. The gas may also contain unreacted aromatic raw materials and by-products of liquid-phase oxidation, although usually they are present in small or trace quantities, i.e. less than about 2 wt.%. The oxygen content in the gas under pressure after separation comes to about 4 vol.%, preferably up to about 1-4%. The quantity of inert gas components in the composition of the source of oxygen, which usually represent nitrogen and oxides of carbon, up to about 45 vol.% from the volume of gas under pressure; when using air as the source of gaseous oxygen, the nitrogen content in the gas under pressure is usually about 30-40%vol.

Preferably, the pressure in the second vapor phase high pressure after the separation was about 1 kg/cm2less than the pressure in the reaction liquid-phase oxidation. Preferably, the temperature of the high pressure gas after the separation was approximately 20°C lower than the temperature of the reaction liquid-phase oxidation, and more preferably about 5-15°C. below the temperature of the oxidation reaction. Preferably, the temperature of the high pressure gas after the separation was above about 100°C., more preferably above about 120°C and below p is IMEMO 250°C, more preferably, below about 230°C. the Pressure of the gas remaining after separation is approximately 4-40 kg/cm2.

The second steam of the high pressure phase, selected after separation, can be directed to the section of condensation from the vapor phase of liquid condensate containing water, virtually free of organic impurities such as solvent monocarboxylic acid and by-products of the oxidation of aromatic raw material and solvent from the stage of oxidation. The condensing section may include any means effective for condensation water, virtually free of organic impurities from the high-pressure gas supplied to the condensing section. It is preferable to include one or more condensers or heat exchangers, effective for indirect heat transfer between the gas phase high pressure and solar heaters, preferably liquid coolant. You can use a single device or multiple devices. Examples of preferred devices are shell-and-tube heat exchanger and casing capacitors. It is preferable to apply the whole or almost the whole high-pressure steam after separation in the condensing section for distribution as heat, and the contained substances. Preferably the cooling in such conditions, to exhaust and the section of condensation of gas after condensation of liquid condensate remained under pressure, not less than the pressure of the gas fed to the condensing section, so you can take the device for condensation. The exhaust gas pressure of the condensing section contains non-condensable components of high pressure gas from a section of the separation, the gaseous byproducts of the reaction and may also contain small amounts of aromatic raw materials from waste gas or phlegmy submitted to the division, which remain undivided in the second vapor phase high pressure. Most preferably, the exhaust gas from the condensing section was at a temperature of 50-150°C. and under a pressure that is less than the gas pressure at the inlet of the condensing section is not more than 3 kg/cm2. More preferably, the difference in pressure of the gas discharged from the device for separation and flue gas condensing section after condensation of liquid condensate was about 2 kg/cm2or less and most preferably about 0.5-1 kg/cm2.

The cooled high-pressure gas by heat exchange with solar heaters in the condensing section also serves as a means of heating the solar heaters. Preferably, the solar heaters was a heat-exchange fluid, and most preferably water. When using water as heat transfer fluid t is loobman with high-pressure gas after the separation of the turns water into steam, which can be submitted to other parts of the proposed method for heating or for use outside of the way. Similarly, the heat exchange between the pressurized gas and liquids from other stages of the method can be used to heat these fluids. Thus, the invention includes variants in which the heat exchange between the high-pressure gas from a section of the division served in the condensing section, and a heat exchange fluid, containing water, is carried out in several heat exchangers operating at successively lower temperatures with the formation of the heat of water vapor at different pressures. Preferably applying steam at different pressures at one or more stages of method, which couples with a corresponding pressure or pressures are used to heat and pressure forms a liquid condensate containing water at successively lower temperatures.

The energy of the exhaust gas from the condensing section can be isolated in the form of heat, in the form of work or in both forms. The release of energy in the form of heat for the process can reduce the consumption of fuel for the process, which otherwise would be required to generate heat. The energy released in the form of work, can be turned into electricity for use in the process, which reduces electricity consumption, is if it is used, from external sources.

While the preferred variants of the invention include condensation of all or almost all high-pressure gas supplied to the condensing section, in some embodiments of the invention the condensation of high pressure gas removed from a section of the separation is carried out by exhaust heat of the gas in such a way that condenses only part contained in the gas or water is fed to the condensation portion of the second vapor phase high pressure after the separation, and the other part serves on the release of energy by transformation into mechanical energy. Incomplete condensation of the second vapor phase high pressure allotted after phase separation, or release from the stream to condense a portion of allows you to receive liquid condensate containing almost pure water with low content of organic impurities and used as phlegmy for separation, as described above, and utilization of thermal energy of the heat exchange fluid by cooling the high pressure gas to form a liquid condensate, which remains neskondensirovannyh water in the exhaust gas from the condensing section of high pressure, which then gives off energy in the form of work.

According to other variants of the invention the entire or almost the entire second steam phase high is Alenia after separation monocarboxylic acid and water from the vapor phase high pressure after oxidation and by-products of oxidation condense through heat exchange with a heat-absorbing fluid. Condensation of all or substantially all condensed components of high pressure gas after separation reduces the volumetric flow of gas remaining after the condensation, the following processing stages and allows the use of metals with low or moderate corrosion resistance such as stainless steel, mild steel or two-phase steel, as an alternative to the more expensive, highly resistant to corrosion of metals and alloys in the equipment for subsequent processing stages of exhaust gas that can be included in the method. Almost complete condensation of the condensed components of high pressure gas discharged after separation also increases the amount of liquid condensate containing water, practically free from organic impurities generated in the proposed method, and may facilitate increased allocation of aromatic raw materials and solvent monocarboxylic acid - or by-products of liquid-phase oxidation of remaining in nscontainerbox gas after condensation.

Condensation can be one. It can also be carried out in several stages, in which the flow of high pressure gas after the section division is cooled to the first temperature in the first stage with the formation of liquid condensate from the first stage and neskondensirovannyh part of the gas that ZAT is m condense at a lower temperature in the second stage to form a liquid condensate of the second stage and neskondensirovannyh part of the gas, supplied to the second stage, and optionally one or more additional stages, which neskondensirovannyh part of the gas from the previous phases condense at a lower temperature than in the previous stages, with the formation of liquid condensate and the remaining neskondensirovannyh part of the gas. The heat exchange between the gas pressure and its nscontainerframe parts in stage capacitors leads to the flow of heat transfer at different temperatures or pressures, for example, streams with medium and low pressure, which can be used for heating other parts of the way or out of the way. In preferred embodiments of the invention for utilization of the energy produced pairs of two or more pressure levels that are traditionally carried out by condensation or by using another turbine on a pair of low pressure. In such embodiments, the liquid condensate, selected at different temperatures, you can apply for other use in the method at appropriate temperatures, thus avoiding additional heating or cooling portions of the condensate and, in some cases with limited accumulation of impurities such as by-products of the oxidation of the solvent monocarboxylic acid, on stages, in which return of liquid condensates. For example, liquid condensates, the selected p and higher temperatures, for example in the range of 130-160°C, can be used at a small additional heat or without him as phlegmy for separation as such or in combination with aqueous liquids with other stages of the method, such as the mother liquor after separation and/or separation of the purified aromatic carboxylic acid at the stage of purification. Such high-temperature liquid condensates are particularly useful if they are applied as phlegmy to separate, due to a lower content of light components, such as lower alcohols and esters of solvent monocarboxylic acid, which are formed as by-products of the oxidation of the solvent liquid-phase oxidation and tend to condense in higher concentrations in the liquid condensates formed at lower temperatures. The condensates obtained at lower temperatures, for example in the range of about 60-90°C, are also quite suitable for use as hot condensate for such purposes as washing liquid for the product separation and isolation of the liquid in the liquid-phase oxidation treatment or in both capacities, and cooler condensate, for example in the range of about 40-50°C, suitable for use as cold water, for example, for cleaning scrubbers. While condensation at different tempera is Urach, at which liquid condensate may be directed to other purposes compatible with the temperatures, creates opportunities for economical power consumption in the proposed method, it should be emphasized that portion of the liquid condensate or flows, condensed at higher and lower temperatures than necessary or preferable to other stages, for use in other stages optionally cooling or heating, for example, by heat exchange.

Preferably, the exhaust gas from the condensing section was under pressure, and although it contains almost no water vapor, according to preferred variants of the invention it may hold some water from the second vapor phase high pressure after division, depending on the degree of condensation at the stage of condensation. In addition to water vapor of the exhaust gas may contain non-condensable components from the exhaust gas of liquid-phase oxidation, such as unreacted oxygen from the stage of oxidation, nitrogen, oxides of carbon and other components of the inert gas present in the source of oxygen for oxidation, and carbon dioxide, and may contain small amounts of by-products of the oxidation of the solvent monocarboxylic acid - oxidation steps and traces of solvent monocarboxylic acid, other porosnietym oxidation and unreacted raw materials aromatic hydrocarbons are not removed at other stages. Even in cases where almost all the water in the exhaust gas condensed into a liquid condensate, so neskondensirovannyh exhaust gas remaining after the condensation, contains almost no water pressure exhaust gas remains relatively high, and especially in the case where a gaseous source of oxygen for liquid-phase oxidation is air or another gas mixture with a high content of inert gas, so that the vapor phase abstracted from the stage of oxidation, and, in turn, gases under pressure from the stage of separation and from the condensing section contain significant amounts of inert gas, the volume of exhaust gas from section condensation is that it can be a useful source of energy utilization.

According to variants of the present invention the energy of the exhaust gas under pressure can be disposed of by condensation. It is preferable to utilize energy in the form of work. In these embodiments, the flow of gas under pressure exhaust gas from the condensing section - serves, directly or indirectly, in the device for energy recovery in the form of work. The preferred device for energy recovery is an expander or a similar device, adapted to receive the flow of gas under pressure and provided with blades, which is s rotate in the gas stream, generating work that is used at other stages of the way or out of the way, and the cooled gas at reduced pressure. The working gas under pressure can be used, for example, to generate electricity using a generator or a compressor that compresses the gas or gaseous sources of oxygen used in liquid-phase oxidation, or other equipment where needed mechanical work. This recycled energy can be used anywhere in the way or in other ways. Alternative it is possible to store or send in the electrical network to supply other items. The exhaust gas remaining after recycling energy in the form of work, you can throw preferably after additional processing, such as condensation for removal of water, if it is present in appreciable quantities in the exhaust gas in the condensing section, and leaching of caustic soda in the scrubber for removal of bromine or other compounds that you do not want to throw into the atmosphere. If desired, the energy can be recycled after washing in the scrubber or processing other way to remove corrosive components. Remove corrosion of components to energy recovery can be useful from the point of view of the design of the internal elements of the expander or other device for the pre is obrazovaniya capacity of less corrosion resistant materials compared with in another preferred case; however, treatment for the removal of such components can also reduce the utilized capacity of the gas.

Alternatively, the utilization of the energy of the exhaust gas at high pressure from a section of condensation or more preferably as an additional stage preceding the utilization of energy in the form of work, as described above, the exhaust gas from the condensing section can be treated to remove organic or other combustible compounds and corrosive components. Such treatments in some embodiments, particularly useful for separation of small amounts of the reaction products of the oxidation of the solvent monocarboxylic acid, and traces of unreacted raw materials, aromatic hydrocarbon, which remains in the exhaust gas. In those embodiments of the invention, in which the condensation of the high pressure gas after separation includes one or more stages of condensation at a temperature low enough that the water in Gaza almost all and preferably at least about 80% condensed and volatile impurities, such as lower alcohols and esters, the reaction products of the solvent monocarboxylic acid, remained in neskondensirovannyh the exhaust gas that has been sufficiently cooled, preferably to a temperature of about 40-90°C., the processing for selecting such is remesa easier because neskondensirovannyh exhaust gas is sufficiently cold to use liquid reagents when washed in the scrubber. In other embodiments, the treatment is useful to reduce the content or the removal of organic compounds such as unreacted raw materials and by-products of the oxidation of the solvent, if they were not removed, and corrosion by-products of the reaction of allylbromide formed by liquid-phase oxidation in which the source of bromine is used as a promoter and catalyst of liquid-phase oxidation caught in the vapour phase high pressure formed by liquid-phase oxidation, and, in turn, in the high-pressure gas selected after the separation, and the exhaust gas after condensation. It is essential that such treatments can affect the amount of utilized energy from the exhaust gas after condensation. Accordingly, in embodiments of the invention, in which the exhaust gas from the condensing section to handle the recycling of energy in the form of work, the preferred treatment is carried out without appreciable loss of pressure or gas volume. If the exhaust gas from the condensing section contains an appreciable amount of water, it is also preferred that any such treatment was carried out without substantial condensation of water from gas or cooling to such an extent that utilize the Oia energy in the form of work has led to significant condensation of water. In such scenarios, it is useful to recycle energy to heat the treated gas.

In embodiments of the invention, including the processing of waste gas under pressure after condensation to remove unreacted materials and by-products of the oxidation of the solvent, the resulting liquid-phase oxidation, such as lower esters of solvent monocarboxylic acid, such processing is useful because it allows you to return these components to oxidation. Processing can also lead to a reduction of the content of such impurities in the flow of recycling and their stationary equilibrium concentrations in the whole way. Neskondensirovannyh gas under pressure after the stage of condensation can be brought into contact, preferably at about 35-60°C with liquid reagent in the scrubber with the formation of the washed gas phase with low concentrations of aromatic raw materials and/or byproducts of the oxidation solvent and liquid product containing reagent scrubber and enriched at least unreacted aromatic raw materials and reaction products of the solvent monocarboxylic acid - stage liquid-phase oxidation. Liquid product is preferably returned to the reaction section to the stage of liquid-phase oxidation. Rinse the scrubber can be done using any device on the a and any reagents for contact with the gas stream, including exhaust the high pressure gas after the condensation, in order to remove volatile components such as unreacted raw materials and by-products of the oxidation of the solvent monocarboxylic acid, trapped from the gas in the liquid phase. Usually use the absorption columns high pressure with internal structure, such as a plate and gasket, for making contact between the washed gases and liquid reagents in the scrubber. Suitable reactants for the scrubber are liquid at the temperature of wash gas, in which the removed substances dissolve well. Examples include lower alcohols and carboxylic acids C1-8such as acetic acid, propionic acid, butyric acid, etc. are Preferred liquid reagent for scrubber is a monocarboxylic acid used as a solvent in liquid-phase oxidation, and its mixture with water. Suitable reagents for the scrubber, equipment and their use for the selection of the components of the exhaust gas after the liquid-phase oxidation of aromatic raw materials are described in more detail in U.S. patent 6143925, which is incorporated herein by reference.

The exhaust gas pressure after condensation with pre-treatment or without it for washing unreacted materials or by-products of the oxidation of the solvent, as the description is of higher you can also handle the removal of corrosion and other combustible materials. Although such removal, you can use any means without appreciable loss of pressure and volume of a gas, preferably a gas to remove organic, combustible and corrosive components subjected to oxidation and most preferably catalytic oxidation. Such treatments usually include heating neskondensirovannyh gas under pressure and the flow of exhaust gas pressure after the stage of condensation or washing in the scrubber or other processing and gaseous oxygen in the combustion section under pressure, not less than the pressure of gas under pressure and at elevated temperature effective to oxidize organic, combustible and corrosive components in less corrosive or more environmentally safe gas that contains carbon dioxide and water. Heating under pressure with oxygen, preferably in the presence of a suitable oxidation catalyst, a localized section of the combustion in such a way as not to interrupt the flow of gas under pressure. Gas under pressure before oxidation can optionally be heated. Preheating can be accomplished by any appropriate means, such as heat transfer, direct injection of steam or other suitable methods. Treatment incineration can neoba is consequently enable washed in the scrubber gas under pressure, allotted after burning, removal of acidic inorganic substances such as bromine and hydrogen bromide formed during the oxidation were synthesized in the exhaust gas after the condenser, when the source of bromine is used in liquid-phase oxidation, as noted above.

Catalysts for the catalytic oxidation typically contain at least one transition element of the Periodic table (IUPAC). The preferred metals of the VIII group, and particularly preferred is platinum, palladium, and combinations thereof, particularly preferably one or more additional or auxiliary metals. Such catalytically active metals can be used in the form of compounds such as oxides. Typically, the catalyst is applied on a substrate with a lower catalytic activity or inactive, but quite durable and resistant to high temperature and pressure of the ambient atmosphere in the combustion section. Suitable substrates for catalyst include metal oxides containing one or more metals, examples of which include mullite, spinel, sand, silicon oxide, aluminum oxide, aluminum silicate, titanium oxides and zirconium. You can use different crystalline forms of such substances, such as alpha-, gamma-, Delta and ETA-alumina and the oxides of titanium in the form of rutile and anatase. The content of catalytically active is atalla on the substrate is usually from the mass fraction of a percent up to several weight percent, moreover, a higher content is preferred when processing gases with a high content of water vapor, for example about 20 vol.% or more. The catalysts can be used in any traditional configurations, shapes or sizes. For example, the catalyst may be in the form of tablets, granules, rings, spheres, etc. and they preferably can be molded or printed on hard porous, cellular, perforated or porous structure for contact with the gases in the combustion section, which would not let a current of gas through the partition. Specific examples of catalysts for the catalytic oxidation for treatment of combustion exhaust gas after the condensation according to the invention include from about half a percent to one weight percent palladium deposited on a monolithic carrier of aluminum oxide.

In those embodiments of the present invention, in which the energy is utilized in the form of gas, including exhaust gas after condensation, and especially when such a gas contains a significant amount of water, for example at least about 5 vol.%, the optional gas can be heated to protect the gas supplied to the utilization of energy from liquid water. The heating can be performed before, after or in combination with other treatments or stages of processing, such as the cat is some or catalytic oxidation. In such embodiments, the heating can be accomplished in any suitable way, such as heat transfer or direct injection of steam or other heated gas. Heated to about 200°C. or higher, preferably to temperatures of about 250-350°C, effectively to prevent condensation of water.

In addition to the exhaust gas section of condensation remaining after condensation of high pressure gas from a section of the separation, condensation as the stage of processing the exhaust gas of the proposed method leads to condensation of liquid from the gas under pressure. Liquid condensate contains almost pure water, as described above, according to preferred variants of the invention serves at least partially in section of the separation of the structure of the liquid phlegmy supplied in section separation. Liquid condensate is also suitable for other purposes, such as wash liquid for separating solid substances and liquids in the case of crude aromatic carboxylic acid obtained by liquid-phase oxidation. If the choice is between a liquid condensate and a second liquid phase enriched water separated after the separation of the exhaust gas, according to the proposed method, the second liquid phase is preferable for use in a comprehensive way that includes cleaning contaminated with aromatic carboxylic acids, such as separation is installed after the liquid-phase oxidation, due to the low level side oxidation products of the solvent monocarboxylic acid in comparison with the liquid condensate is separated from the second vapor phase high pressure after the separation.

In embodiments of the invention, including cleaning or production of purified aromatic carboxylic acids, cleaning includes at least one stage, which represents the contacting with hydrogen at elevated temperature and pressure in the presence of a catalyst containing an active hydrogenation metal and the solution for the reaction cleanup containing a liquid which includes water and dissolved aromatic carboxylic acid and impurities, to form a liquid reaction mixture cleanup containing aromatic carboxylic acid and hydrogenated impurities dissolved in a liquid containing water. In preferred embodiments, the reaction of the cleaning solution is formed by dissolving in a liquid containing water, the crude product is selected after the liquid-phase oxidation and containing an aromatic carboxylic acid and impurities comprising by-products of the oxidation of aromatic raw materials. Pure samples of aromatic carboxylic acids containing a lower concentration of impurities, can be isolated from the liquid reaction mixture cleanup preferably the crystal is izala, and the resulting pure product can be separated from the liquid mother liquor purification remaining after allocation of the net product and/or one or more water-containing fluids, such as solvents for crystallization and washing liquid. The present invention includes variants in which at least one liquid containing water, which is used for cleaning, is a second liquid phase enriched water, after the section of the separation of exhaust gas according to the invention. As shown above, in other embodiments, the mother liquor after cleaning at least one cleaning serves on the division of the exhaust gas in the partition splitting as phlegmy containing water.

As described above, an aromatic carboxylic acid obtained by liquid-phase oxidation of a raw material, which consists of aromatic compounds with oxidizable substituents, also sometimes referred to as crude aromatic carboxylic acids or the raw product of liquid-phase oxidation, contain aromatic carboxylic acid and one or more intermediate oxidation products or by-products. Although the exact chemical composition of intermediate products or by-products vary depending on the composition of the raw materials, reaction conditions, oxidation and other factors and even to this raw material is not quite of the local, it is clear that they contain one or more aromatic carbonyl compounds, such as benzaldehyde, carboxybenzaldehydes, fluorenone and anthraquinones, which determine or correlate with unwanted color derived from the specific aromatic carboxylic acids or of polyesters and can be provideruri in compounds more soluble in aqueous solution than aromatic carbonyl compounds and aromatic carboxylic acid, or compounds, less colored or with a tendency towards the formation of color. Preferred crude aromatic carboxylic acid, which should be cleaned according to variants of the invention represent a crude product containing aromatic carboxylic acid and by-products obtained during liquid-phase oxidation of aromatic raw materials, and most preferably a continuous process with the stages of liquid-phase oxidation and purification was integrated to a crude solid product liquid-phase oxidation was the starting material for purification. However, it should be emphasized that the starting material for the purification may represent or include crude product containing aromatic carboxylic acid and an aromatic carbonyl impurities, as described above, either present or formed as poboon the e products are complex or non-complex liquid-phase oxidation of aromatic raw materials or other processes or sources. Thus, the invention includes variants in which the crude aromatic carboxylic acid, a starting material for purification, contains an aromatic carboxylic acid and at least one aromatic carbonyl impurity that forms hydrogenated carbonization aromatic product with a higher solubility in aqueous solution and less colored and contributing coloring than digidrirovannye aromatic carbonyl impurities. Untreated samples of aromatic carboxylic acid, the starting materials for cleaning, including raw foods, selected liquid-phase oxidation, according to variants of the invention can also contain small amounts of residual solvent monocarboxylic acid. Number from several hundred to a thousand ppm by weight, which are usually present in the products of the industrial liquid-phase oxidation, does not adversely affect the cleaning of the proposed method. Most preferably, the content of the solvent monocarboxylic acid in the resulting aromatic carboxylic acid before cleaning does not exceed about 10 wt.%.

In more detail, the preferred cleaning stage according to this invention comprises dissolving in a liquid containing water at least part of which the most is it preferably represents a second liquid phase, containing water, separated after the separation of the exhaust gas according to the invention, solid product containing aromatic carboxylic acid and impurities, with formation of a reaction solution treatment, the contacting of the cleaning solution at an elevated temperature and pressure with hydrogen in the presence of a hydrogenation catalyst to form a liquid reaction mixture, purification, separation from a liquid reaction mixture treatment of solid purified product containing aromatic carboxylic acid with a low concentration of impurities, and separating the aqueous mother liquor purification containing by-products of oxidation, hydrogenation products of their and their combinations from the selected solid purified product.

Hydrogenation of the crude aromatic carboxylic acid to reduce the concentration of impurities is carried out in aqueous solution. The preferred solvent for solution purification in some embodiments of the invention includes a second liquid phase obtained after removal of the partition separating the exhaust gas according to the invention. In a continuous and integrated methods, it is preferable to apply the second liquid phase after separation without additional or intermediate processing in order to remove by-products or impurities, in order to avoid additional costs, complexity and the additional equipment for the storage or processing of liquid condensate, although it should be emphasized that cannot be excluded and further processing, although they are not necessary when using the second liquid phase as solvent cleaning. Similarly, although it is not necessary to obtain a fluid of sufficient purity to be used as solvent cleaning according to the invention, it is important that this invention provides for the use of other suitable sources of water, such as fresh demineralized water or other sources of purified water along with the second liquid phase after separation of the exhaust gas or instead of it. Preferably, the second liquid phase enriched water, after separation according to the invention, constituted by at least about 50% of the solvent for the reaction of the cleaning solution, and more preferably about 80-100%.

Concentration of the crude aromatic carboxylic acid in solvent cleaning, which should handle the cleanup phase, usually quite low, so that the crude acid is mostly dissolved, and high enough for practical work, effective use and manipulation of the liquid used as a solvent, and its presence in uterine fluid purification after extraction of the pure forms of aromatic carboxylic acid with reduced of soderzhaniya purification from the reaction mixture. Solutions containing about 5-50 parts by weight of the crude aromatic carboxylic acid per hundred parts by weight of solution at temperatures of way, provide appropriate solubility for practical operations. Preferred reaction cleaning solutions contain about 10-40 wt.% and more preferably about 20-35 wt.% the crude aromatic carboxylic acid at temperatures used for cleaning by the method of catalytic hydrogenation.

Catalysts suitable for use in reactions purification by hydrogenation, contain one or more metals, catalytically active in the hydrogenation of impurities in the crude aromatic carboxylic acids, such as intermediate oxidation products, by-products of oxidation and/or aromatic carbonyl compounds. It is preferable to apply a catalytically active metal on a substrate which is insoluble in water and erectiondosan in relation to aromatic carboxylic acids in terms of cleaning method. Suitable catalytically active metals are the metals of group VIII of the Periodic table of elements (IUPAC version), including palladium, platinum, rhodium, osmium, ruthenium, iridium, and combinations thereof. The preferred palladium or combinations of these metals, including palladium. Site is titlename carriers are coals and charcoal with the values of the surface in a few hundred or thousand m 2/g and sufficient strength and abrasion resistance with long-term use at operating conditions. The metal content is not critical, but almost preferred the metal content is about 0.1-5 wt.% calculated on the total weight of the carrier and a catalytically active metal or metals. Preferred catalysts for the conversion of the impurities contained in the crude aromatic carboxylic acids, including crude terephthalic acid obtained by liquid-phase oxidation of a raw material on the basis of para-xylene, contain about 0.1-3 wt.% and more preferably about 0.2 to 1 wt.% active hydrogenation metal. For these purposes, the preferred palladium.

For practical use the most convenient catalyst in the form of particles, such as pellets, extrudate, spheres or pellets, although other forms of particles. The particle size of the catalyst is chosen so that the catalyst bed was easy to maintain in the reactor cleaning, but to the flow of the reaction mixture to clean passed through the layer without causing undesirable pressure jump. The preferred average particle size of the catalyst is such that the particles passed through a sieve of 2 mesh, but was retained on a sieve of 24 mesh (series of sieves USA) and more preferably so that they pass through a sieve 4 mesh, but hold is Alice on the sieve 12 mesh and most preferably at 8 sieve mesh.

Contacting the aqueous reaction solution cleaning with hydrogen in the presence of a catalyst is carried out at elevated temperatures and pressures. Temperature range is approximately 200-370°C, preferably 225-325°C and most preferably about 240-300°C. Cleaning is performed at a pressure sufficient to maintain liquid phase containing aqueous reaction solution. The total pressure at least equal to or preferably above the sum of partial pressures introduced into the process of hydrogen and water vapor, which evaporates from the aqueous reaction solution at the operating temperature. The preferred pressure is from about 35 and more preferably about 70 to about 105 kg/cm2.

The aqueous reaction solution purification is brought into contact with hydrogen at hydrogenation conditions as described above, in a suitable reaction vessel capable of withstanding the temperature and pressure hydrogenation and acidic liquid contents. The preferred design of the reactor is a cylindrical reactor with a Central axis that when the reactor is vertical. You can use reactors with upward and downward flows. The catalyst is usually placed in the reactor in the form of one or more rigid layers, in which the particles of catalyst supports mechanical is oblozhka, through which relatively freely passing the reaction solution. Often prefer one layer of catalyst, although you can use many layers of the same or different catalysts, or one layer with different catalysts, for example with different size particles of the catalytically active metal or metal content, or the catalyst with other substances, such as abrasives, for his protection. Often use mechanical substrate in the form of a flat sieve or grid consisting of parallel wires arranged accordingly. Other ways to support the catalyst include, for example, tubular sieve Johnson or perforated plate. The internal elements and the surface of the reactor and the mechanical substrate for a catalyst layer made of a material resistant to corrosion by contact with the acidic reaction solution obtained products. The most suitable substrate for the catalyst layers have openings of about 1 mm or less and made from metals such as stainless steel, titanium or Hastelloy C.

In a preferred embodiment of the invention an aqueous solution of impure aromatic carboxylic acid, which should be clear, is introduced into the reaction vessel at elevated temperature and pressure in the upper part of the reactor or close to it and the solution pod is tons downflow through the catalyst bed, contained in the reaction vessel in the presence of hydrogen and impurities recovered hydrogen is often with the formation of hydrogenated products, better soluble in the reaction medium than the target aromatic carboxylic acid, or less intensely colored or affect the color of the product. In a preferred embodiment, the liquid reaction mixture cleanup containing aromatic carboxylic acid and hydrogenated impurities are removed from the reaction vessel in the lower part of the reactor or very close to it, or from the bottom of the reactor.

The reactors used for cleaning, can work in several ways. In one case, the reactor can maintain a given liquid level and the pressure in the reactor feeding hydrogen at a rate sufficient to maintain a given liquid level. The difference between the actual pressure of hydrogen and the vapor pressure of the vaporized cleaning solution in the main pursuit of the reactor is equal to the partial pressure of hydrogen in the main race. Alternative hydrogen can be fed in a mixture with an inert gas, such as nitrogen, or water vapor, and in this case, the difference between the actual pressure of hydrogen and the vapor pressure of the vaporized reaction solution is equal to the sum of partial pressures of hydrogen and impurities inert gas. In this case, the partial pressure of hydrogen can be the about be calculated from the known relative quantities of hydrogen and inert gas in the mixture.

In another embodiment, the operation of the reactor can be filled aqueous reaction solution without steam space, but with the hydrogen bubble in the upper part or head of the reactor; this bubble expands or shrinks in size, providing the volume in the cylinder of the reactor, so that fed into the reactor, the hydrogen is dissolved in the incoming reaction solution purification. In this embodiment, the reactor operates as a hydraulically filled the system with dissolved hydrogen fed to the reactor using flow control. The concentration of hydrogen in solution can be varied by setting the flow rate of hydrogen in the reactor. Optionally, you can calculate pseudoparticle pressure hydrogen from the hydrogen concentration in solution, which, in turn, can be correlated with the flow rate of hydrogen in the reactor.

Regulation of the process by setting the partial pressure of hydrogen preferably, the partial pressure of hydrogen in the reactor ranged from half to about 15 kg/cm2or more depending on the pressure in the reactor, the concentration of impurities in the crude aromatic carboxylic acid, activity and life of the catalyst and other parameters understood by the experts in this field. In the case when the process is regulated by direct reference hydrogen concentration in rastvoreniya, the solution is likely to be less saturated with hydrogen and the reactor itself is hydraulically filled. Thus, establishing the desired feed rate of hydrogen in the reactor allows to adequately regulate the concentration of hydrogen in solution.

Space velocity, defined as the mass of the crude aromatic acid on the weight of catalyst per hour, in the course of the hydrogenation is usually about 1-25 h-1and preferably about 2-15 h-1. The contact time of the liquid stream to clean the layer of catalyst will vary depending on flow rate.

Pure aromatic carboxylic acid with a low concentration of impurities compared to raw or other crude aromatic carboxylic acid used to prepare the cleaning solution, separated from the liquid reaction mixture treatment. The reaction mixture was clean, containing water, the solvent is dissolved in the aromatic carboxylic acid and gidrirovanie aromatic impurities, it is better soluble in the aqueous reaction medium than their digidrirovannye predecessors, is cooled to obtain pure form of solid aromatic carboxylic acid with reduced levels of impurities of the reaction mixture, leaving a liquid purification mother liquor which contains dissolved hydrogenated impurities. Vyd the separation is usually achieved by cooling to the crystallization temperature, which is rather low for crystallization of aromatic carboxylic acid, which leads to the separation of the crystals from the liquid phase. The crystallization temperature is high enough so that the dissolved impurities and products of their recovery, formed after hydrogenation, remain dissolved in the liquid phase. Typically, the crystallization temperature is in the range of up to 160°C and preferably to about 150°C. In continuous operation selection usually includes the selection of purification of the reaction mixture from the reactor purification and crystallization of aromatic carboxylic acids in one or more vessels for crystallization. When carrying out the successive stages or in separate vessels crystallization temperature at different stages or in different vessels may be the same or different and preferably may be reduced from the stage or vessel to the next stage or vessel. Crystallization usually also leads to the formation of wash liquid from the reaction mixture of cleaning that can be allocated by the condensation and return to one or more purification stages, one or more stages of crystallization in the upstream or in the preferred embodiments of the invention for the separation of solvent monocarboxylic acid and water vapour in the vapour phase high pressure after the liquid-phase oxidation. The liquids is ü, containing water, which preferably is an enriched liquid water allocated in the form of a second liquid phase in the separation of exhaust gas according to the proposed method, it is preferable to add to the product crystallization isolated from the reaction mixture purification, selected in stage crystallization, either directly or, more preferably, indirectly, in one or more wash fluid product crystallization.

Then the purified crystalline aromatic carboxylic acid is separated from the mother liquor purification, containing dissolved hydrogenated impurities. Department of crystalline pure product is usually carried out by centrifugation or filtration. The preferred separation enables filtering aqueous suspension of pure aromatic carboxylic acid and washing the precipitate on the filter with a liquid containing water as described in U.S. patent 5175355, which is incorporated herein by reference. Enriched with water and the second liquid phase after separation off-gas separation, as described here, is the preferred fluid, containing water, for use as wash liquid for pure aromatic carboxylic acid.

Royal cleaning solution remaining after separation of the solid purified aromatic carboxylic acid from p the promotional mix cleaning, contains water and hydrogenated derivatives by-products or impurities present in the original crude aromatic carboxylic acid. The mother solution also typically contains a small amount of aromatic carboxylic acid, which remains in solution. Such hydrogenated derivatives include compounds that can be converted into aromatic carboxylic acid by liquid-phase oxidation, and accordingly, in preferred embodiments of the invention at least part of such hydrogenated derivatives are served directly or indirectly on the liquid-phase oxidation. Remaining in the mother solution of the aromatic carboxylic acid can also be directly or indirectly on the liquid-phase oxidation after separation of such hydrogenated derivatives, or more preferably together with them. The filing of such derivatives and aromatic carboxylic acids by oxidation traditionally performed by feeding at least part of the mother liquor remaining after separation of the solid pure forms of aromatic carboxylic acid, at a stage of liquid-phase oxidation. Water contained in the mother solution, cleaning can upset the balance of water in the oxidation, if the water from the mother liquor fed to the oxidation, will not be counted in other threads that you can return to oxidation. The supply Geri avannah impurities in the mother solution treatment as such or preferably in combination with an aromatic carboxylic acid, present in the mother solution, the liquid-phase oxidation preferably takes place without disturbing the water balance in the oxidation. More preferably, at least part, and most preferably almost all of the mother liquor remaining after separation of the solid purified aromatic carboxylic acid from the liquid reaction mixture cleaning, feeding, directly or indirectly, in the section of the branch exhaust gas according to the invention, where it is used as phlegmy, as described above. Reactor cleaning, a layer of catalyst and job details, as well as a detailed method of crystallization and extraction of product and equipment used in the method according to the invention, described in more detail in U.S. patent 3584039, 4626598, 4629715, 4782181, 4892972, 5175355, 5354898, 5362908 and 5616792, which are included by reference.

Figure 1 illustrates in more detail the variants of the method of production of aromatic carboxylic acids and apparatus for separating the exhaust gas according to the invention. As shown in the figure and described with particular reference to the production of selected aromatic carboxylic acid is terephthalic acid by liquid-phase oxidation of para-xylene as the preferred raw material in the liquid-phase reaction mixture containing water and acetic acid as a solvent monocarboxylic acid - for whom islene and separation from flue gas containing acetic acid, water and by-products of oxidation, and further preferred options and features of the invention, according to which the oxidation and separation off-gas is integrated with additional steps, including the selection and separation of the crude product of liquid-phase oxidation, purge product of liquid-phase oxidation and various additional products, and utilization of energy, it becomes clear that specific options, features, details and preferences described in order to assist in understanding the invention but not to limit it or its features in any aspect or embodiment.

The method, illustrated in figure 1, reflects the preferred options of the proposed method, in which liquid-phase oxidation, separation of the exhaust gas and the cleaning integrated so that the resulting liquid-phase oxidation of crude aromatic carboxylic acid is fed to the cleaning for education solution purification of exhaust gas of the high pressure stage of oxidation is supplied to the separation of the exhaust gas, the liquid phase after separation off-gas is used as a liquid for cleaning, and phlegm to separate the mother liquor contains from the stage of purification; however, it is clear that the invention should not be construed as limited icanoe only presented on the figure of the integrated circuit, since the invention includes various serial, serial-to-parallel and other integrated and reintegrirovat configuration. According to the examples of a product containing an aromatic carboxylic acid and by-products of several reactions liquid-phase oxidation, it is possible to apply for one purification step, which serves as a fluid liquid phase, isolated by separation of the exhaust gas from the vapor phase high pressure after one or more stages of liquid-phase oxidation. As additional examples, the crude product after a single liquid-phase oxidation can be cleaned in a separate purification units connected in parallel, in the presence of steam with high pressure phase after oxidation of the liquid from which the separated exhaust gas to highlight enriched water liquid phase, containing no by-products of the oxidation of the solvent, and applying either one or both of such apparatus, as well as it serves as an alternative or complement to the way in which the crude aromatic carboxylic acid after oxidation or process is cleaned by the cleaning method or the steps of the method described here.

The figure also presents the apparatus for separation according to the invention and also the following variants of the invention in which the apparatus is integrated into more about the equipment such as the reaction vessel for liquid-phase oxidation.

Liquid and gas flows, and agents involved in the way presented in figure 1, is usually served and transferred via the appropriate transport lines, pipes and pipelines made of appropriate materials for safe use in the method. It is clear that the individual elements can be mechanically impose on each other and they may contain, where necessary, flexible scope, hard scope, or both. For submission of threads or connections you can use the intermediate apparatus or optional treatments. For example, you can use the corresponding pumps, valves, manifolds, flow meters for gas and liquids and distributors, the device for sampling and sensor devices and other equipment for monitoring, regulation, establishment and change of pressure, flow and other operational parameters.

In the figure, the separation apparatus 330 is a column with a closed inner space adapted to receive the vapor phase high pressure removed from the oxidation reactor 110 in the stream 111, and for removal of the second vapor phase high pressure through the gas outlet 334. It also includes inputs 336 and 344 to supply phlegmy from external sources, such as streams from other stages of method or of temporarily what's vessels. Between inputs phlegmy 336 and 344 is output 345 to remove the second liquid phase collected in the column. The structure of the internal space of the column between the inlet for receiving the vapor phase high pressure from the oxidation reactor 110 and the input phlegmy 336 generates within the separation zone.

A device for the separation is designed so that you can almost divide monocarboxylic acid C1-8and the water in the upper chase gas at high pressure and temperature reactor oxidation supplied to the device, and it is preferable to distribute the by-products of liquid-phase oxidation with the formation of the first liquid phase enriched monocarboxylic by Crotoy, and a second liquid phase enriched water, but containing no solvent and by-products of its oxidation, formed by liquid-phase oxidation, and a second vapor phase high-pressure, water-containing and not containing the solvent and by-products of the oxidation of aromatic raw materials of liquid-phase oxidation. In preferred embodiments, a direct connection or a close interaction of the oxidation reactor and device for separation of amplified through direct binding or through suitable pipes or other pipes between one or more inputs in a vessel for oxidation reactions and one or more gas inlets in the device for RA the division, to vapor phase under conditions of liquid-phase reactions were assigned from the reaction vessel and was served in a device for the separation at the same temperature or the same temperature and pressure that section of the response.

Section of the fractionation device for separating arranged with a number of theoretical equilibrium stages, such as formed internal plates, structural gasket, combinations of plates and gaskets or other structures or combinations thereof, forming a surface within the device for mass transfer between gas and liquid phases in the device. Is formed at least about 20 theoretical equilibrium stages. The separation efficiency increases with the number of theoretical equilibrium stages ceteris paribus, so that theoretical upper limit on the number of equilibrium stages in the separation apparatus according to the invention is absent. However, for practical purposes, the separation at which the solvent monocarboxylic acid in the vapor phase high pressure filed in a device for the separation, almost were selected would be in the liquid phase can be carried out with the help of at least about 20 and preferably at least about 25 theoretical equilibrium stages, while the separation achievable with the help of about 100 such is Tadi, requires additional stages and becomes economically inefficient.

In the preferred device for the separation with the structural gasket is at least about 3 layers or zones gaskets and more preferably about 4-8 of these layers, providing adequate surface and theoretical equilibrium stage separation. An example of a suitable material for the gasket is Flexipac structured from KGGP LLC in the form of thin sheets of corrugated metal, arranged with alternating crossing that creates flow channels, the intersections of which form the point of mixing of the liquid and vapor phases. The preferred device for the separation plates includes approximately 30-90 plates, at least about 70% of which are located between the input of high pressure gas 338 fed to the device for the separation of the reaction vessel, as is best seen in figure 2, and at least one input for liquid phlegmy. Preferred plates in the form of a sieve or bubble cap with a separation efficiency of about 30-60%. The number of plates for a given number of theoretical equilibrium stages can be calculated by dividing the number of stages on the efficiency of the dish.

When implementing the method of the gas and liquid phase filed in a device for the separation, there are at elevated temp is the temperature and contain water, the solvent monocarboxylic acid and other corrosive components, such as bromine compounds and their products of dissociation, such as hydrogen bromide, which are present in the gas of the upper chase reactor oxidation, when used for the oxidation catalyst contains a source of bromine. Therefore, in preferred embodiments of the invention, the internal structure and other elements of the apparatus for separation, which, when in contact with gases and liquids, made of suitable metal, resistant to corrosion and other damage as a result of this contact. The preferred material for constructing such surfaces, including plates, a gasket or other structure section of the fractionation, the metal is titanium. On the surface of titanium in such structures can accumulate unwanted sediments containing iron oxides of the impurities present in the fluids circulating in the equipment. Methods of control of accumulation of precipitation of iron oxides or content of soluble iron impurities in the working fluid is described in U.S. patent 6852879 and 2002/374719, which is incorporated herein by reference.

In a variant of the invention represented in the drawings, a device for the separation of 330 represents a distillation column high pressure with many plates, concrete etc the measures which 333 and 337 are best shown in figure 2. In addition, as can be seen in figure 2, the column includes at least one lower output 332 to drain the liquid from the column, for example, by oxidation. The gas inlet 338 is located in the lower part of the column for receiving the exhaust gas from the oxidation reactor and the hole 334 is in the top for venting the second vapor phase high pressure as the gas outlet. For stage separation according to the invention the area between the gas inlet 338 and enter the liquid phlegmy 344 includes a plate corresponding to theoretical equilibrium stages for practical separating solvent monocarboxylic acid and water in the vapor phase high pressure abstracted from the stage of liquid-phase oxidation in the first stage or the first part of the column 330. A plate located between the input phlegmy 344 and the output of the second liquid 345 corresponding to theoretical equilibrium stages for separation of by-products of the oxidation of aromatic raw materials and water with the distribution of such products in the liquid phlegm, form the second part of the section of the separation in the column. A plate located between the liquid 345 and input phlegmy 336, presents under the numbers 333 and 337, form theoretical stage for separation of by-products of the oxidation of the solvent monocarboxylic acid and water in the third part of the section separation. The output liquid is 332 is located at the bottom for draining the first liquid phase, enriched solvent monocarboxylic acid, separated from the exhaust gas of the oxidation in the first part of section division. And the plate of the bellows, hopper and cumulative channel or other means of draining on its circumference, room 339, is in contact with the liquid 345 and adapted to collect a second liquid phase phlegmy flowing through the separation, and discharge through the exit 345. Conclusion 345 in combination with the internal structure of the division apparatus for collecting phlegmy between the plates or between the layers of gaskets or other structure section of the fractionation, such as the collection 339 form a lateral outlet from the column for collection and removal of the second liquid phase enriched water, which was allocated in the device.

Referring again to figure 1, we see that the separation apparatus is adapted to receive the vapor phase high pressure section of the reaction liquid-phase oxidation 110. In some embodiments, the apparatus according to the invention includes apparatus for separation in combination with at least one reactor liquid-phase oxidation in connection with the separation apparatus, so that the high-pressure gas from the upper shoulder strap, abstracted from the vessel at least one hole for gas upper shoulder strap, such as 116, enters the device for the separation. In such embodiments, the reaction vessel 110 preferably includes PRA is almost cylindrical shell, which restricts almost closed internal volume. When working in the lower part of the inner volume is the liquid reaction mass, and the off-gas reactions in the upper chase is part of the internal volume above the liquid level. The internal volume is in communication with the outer space of the reaction vessel through a variety of inputs, an example of which is 112 in figure 1, through which liquid aromatic raw materials, the solvent and the catalyst solution is supplied from storage vessels fluid (not shown), and the compressed air or other source of gaseous oxygen is supplied from a compressor or other suitable device (not shown) through the respective transport line transfer (not shown). The inputs are preferably positioned so that the liquid and gaseous components are fed below the liquid level inside the vessel. The reaction vessel also has at least one outlet, such as 114, for removal of the internal volume of the liquid reaction mixture, which contains the crude product, including aromatic carboxylic acid and by-products of oxidation. The reaction vessel 110 also includes at least one hole or output, such as 116, removal of the internal volume of the vessel vapor phase high-pressure evaporated from the liquid reaction mass. A hole 116 is preferably races is to alagat in the upper part of the working vessel.

The preferred design of the reaction vessel is made in the form of a cylindrical vessel with a Central axis located at the vessel almost vertically. The vessel is adapted for use with a mechanism for mixing 120 containing a core with one or more blades on it, which can rotate inside the reaction vessel, and stir the liquid reaction mixture during operation. In preferred embodiments of the invention for mixing gaseous and liquid components in the liquid reaction mass on the rod are at least two blades or mixing element, in order to avoid deposition of solids in the lower parts of the vessel. For mixing the reaction system liquid-phase oxidation of suitable and preferably are used in different combinations of axial blades, usually in the form of propellers, radial flow faucets, such as disk turbine with flat blades, dispersing disks, screw rubber mixing elements, turbine with inclined blades on the go and order flow, agitator, anchor type, providing mainly Chancellery flow, and other structures, providing a higher content of solids in the lower regions of the liquid reaction mixture and a higher content in the top fields, which can change the height of the liquid mass. Other constructions are disclosed in U.S. patent 5198156, which describes the use of various elements with radially directed rotating blades flat on the shaft with hollow blades and discrete rib, continuous cascading hem, in the absence of external concave surfaces and with an open outer end, which are mainly used in combination with a vertical tube or perforated spray for gas supply, as well as in U.S. patent 5904423, which describes a mixer in which the mixing elements are arranged on a Central rotating shaft under a downward angle and wedge directed toward the movement of fluid from the radial inner ends of the moving edges of the blades, bent under angle outward with respect to the movement of the blades, and adapted to supply gas from the lower part of the mixing elements in the Central cavity formed conical disk on the end of the shaft.

At least such part of the reaction vessel, as the agitator shaft and the parts that are in the process of working contact with the liquid reaction mixture and the gas of the upper shoulder strap, made of corrosion-resistant materials. Examples include metal titanium, which is preferred alloys and two-phase stainless steel is Tali.

According to a preferred variant of the method presented in figure 1, the liquid raw material containing at least about 99 wt.% para-xylene, aqueous solution of acetic acid, preferably containing about 70-95 wt.% acetic acid, soluble compounds of cobalt and manganese, such as the corresponding acetates, as sources for the catalytically active in the oxidation of metals, bromine in the form of, for example, hydrogen bromide, catalyst promoter and the air continuously served in the reaction vessel oxidation 110, which is a pressure hull reactor with a stirrer, through entrances, one of which is shown for illustration number 112. The solvent and the source of para-xylene is served with such speed that the mass ratio of the solvent and raw materials ranged from 2:1 to about 5:1. Sources of cobalt and manganese is preferably used in amounts of about 100-800 ppm by weight each based on the weight of the original para-xylene. Bromine is preferably used in an amount such that the atomic ratio of bromine and catalytically active metals ranged from about 0.1:1 to about 1.5:1.

Mixing is achieved by rotation of the agitator 120, the shaft of which is driven from an external source (not shown), which makes moving blades on the shaft, finding the iesa in the mass of liquid in the reactor, mixing liquid and dispersive gases in the liquid mass, in order to avoid deposition of solids in the lower areas. The catalyst and the promoter, each preferably in the form of a solution in acetic acid, is fed into the liquid mass in the reaction vessel. The air supplied from the bottom sweep sweep the bottom of the blade with the speed required to achieve a ratio of at least 3 moles of molecular oxygen per mole of aromatic raw materials.

para-Xylene is oxidized in the liquid reaction mixture with stirring in the reactor 110 mainly to terephthalic acid, but also forming byproducts, including products of incomplete and intermediate oxidation, such as 4-carboxybenzene, 1,4-hydroxymethylbenzene acid and p-tolarova acid, and other products type of benzoic acid. Solid reaction products containing terephthalic acid and by-products of the oxidation of para-xylene, are deposited from a liquid reaction mixture, and a smaller number of products remain dissolved in the liquid. The content of solids in liquid suspension is usually about 50 wt.% and preferably about 20-40 wt.%. Water is also formed as a product of the oxidation reaction. The oxidation reaction is exothermic, and the heat causes the boiling liquid reaction mixture and images is the vapor phase of the upper shoulder strap, containing the vaporized acetic acid, water vapor and gaseous by-products of the oxidation reaction, oxides of carbon, nitrogen from the air fed to the reaction, and unreacted oxygen. Vapor phase may also include small amounts of unreacted para-xylene. The internal volume of the reactor 110 is maintained under pressure sufficient to maintain liquid phase in the reaction mixture, preferably about 5-21 kg/cm2. Steam top zipper away from the reactor through the opening 116. The contents of the reactor support at the operating temperature in the range of about 160-225°C depending on the speed of removal of the vapor phase, taking also into account the temperatures and flow rates discharged from the reactor and returned to the reactor as described below.

Liquid waste product containing solid products of the oxidation of para-xylene, including terephthalic acid, suspended in the liquid reaction mixture, also containing dissolved para-xylene, by-products of oxidation and the catalytically active metal is removed from the reaction vessel 110 via the suspension 114 and served in the stream 115 in section crystallization for separation of solid oxidation product containing terephthalic acid and by-products of the oxidation of para-xylene.

In a variant of the invention, represented in figure 1, the crystal is tion is carried out in several vessels crystallization with stirring, 152 and 156, which are connected by a thread to transfer the resulting suspension of 152 in the vessel 156. The cooling vessels crystallization is carried out by pressure relief and cooling the suspension in the vessel 152 to a temperature of about 150-190°C and then about 110-150°C in a vessel 156. One or more vessels of crystallization, such as 154 and 158, serve respectively to exhaust in the heat exchangers (not shown) of steam formed as a result of pressure reduction and evaporation of the liquid. Pairs allocated from one or more consecutive crystallization vessels, such as vessel 152, in the heat exchanger, it is preferable to condense and the liquid condensate containing water, solvent - acetic acid - soluble products and by-products of oxidation, can be submitted in one or more vessels crystallization in downward flow, such as 156, to highlight the crystallizing component, such as terephthalic acid and by-products of oxidation, entering and condensing of the steam in one or more vessels in the course of the stream.

The crystallization vessel 156 is connected with the liquid stream from the separation device 190 solids and liquids, which is adapted to receive from the crystallization vessel suspension of solid product containing terephthalic acid and by-products of oxidation in the fallopian dissolve the e stage of oxidation, containing acetic acid and water, and to separate from the liquid crude solid product containing terephthalic acid and by-products. A device for the separation 190 is a centrifuge, a rotary vacuum filter or filter press. In preferred embodiments of the invention a device for the separation is a press-filter fit for replacement under the pressure of the solvent mother liquor in the sediment on the filter in the wash liquid containing water. The mother solution after oxidation, the resulting separation, out of the separation device 190 in the stream 191 for transfer to the mother liquor tank 192. The main part of the mother liquor is pumped from the reservoir 192 in the oxidation reactor 110 to return to the reaction liquid-phase oxidation of acetic acid, water, a catalyst and by-products of oxidation, dissolved or present in the form of small solid particles in the mother solution. The crude solid product containing terephthalic acid and impurities, including by-products of the oxidation of the original para-xylene served after the intermediate drying and storage or without them from the device for separation of 190 in the vessel 202 in the flow of 197 with the formation of the cleaning solution. The crude solid product is suspended in the reaction solution of the cleaning vessel 202, which whole or in men is our least in part, preferably about 60-100 wt.%, represents the second liquid phase from the separation of the flue gas to water and acetic acid in the vapor phase withdrawn from the reactor 110 in column 330, and the by-products of oxidation. If you use this solution, the solvent, such as fresh demineralized water or suitable threads recycling, for example liquid vapor condensate formed after pressure release during crystallization of the obtained purified terephthalic acid, as discussed below, can be fed into the tank 202 of the vessel 204. The temperature of the suspension in the tank is about 80-100°C.

The crude product is dissolved with the formation of the reaction solution by heating, for example, up to about 260-290°C in the tank 202 or passing it through heat exchangers (not shown) as feed to the reactor cleanup 210. In the reactor 210 the reaction solution purification is brought into contact with hydrogen under pressure preferably in the range of about 85-95 kg/cm2.

Part of the liquid reaction mixture is continuously cleaning away from the hydrogenation reactor 210 in the flow 211 in the crystallization vessel 220, where terephthalic acid with a low concentration of impurities crystallizes from the reaction mixture by lowering the pressure above the liquid. The resulting slurry of purified terephthalic acid and liquid, about sovavsya in vessel 220, served in apparatus for separating solids and liquids 230 on line 221. Pair that occurred when the discharge pressure in the reactor crystallization, can be condensed by passing in heat exchangers (not shown) for cooling and the resulting liquid condensate is re-directed into the process, for example, in the form of a return to the tank cleaned raw material 202 on the relevant transport lines (not shown). Purified terephthalic acid is released from the device for separating solids and liquids 230 in the stream 231. Device for separating solids and liquids can be a centrifuge, a rotary vacuum filter, filter press, or a combination of one or more filters. The second liquid phase selected from the column 330, can be routed to a device for the separation as washing liquid for the separation to replace demineralized water or reduce the need for final rinsing of the pure product.

Royal cleaning solution from which the resulting solid purified terephthalic acid is separated in the separator solids and liquids 230 contains water, a small amount of dissolved and suspended terephthalic acid and impurities, including hydrogenated by-products of oxidation, dissolved or suspended in the mother solution. According to the preferred is sustained fashion variant of the method, presented in figure 1, at least part and preferably all or almost all of the mother liquor purification served in the stream 233 separation off-gas oxidation reaction in the distillation column high pressure 330. Royal cleaning solution aimed in column 330, is fed into the column at the bottom at number 344 as a liquid phlegmy for separation. Transfer the mother liquor purification of the device for separating solids and liquids 230 to a distillation column high pressure also allows you to recover terephthalic acid and impurities in the mother solution, such as by-products - benzoic acid and p-tolarova acid in the oxidation reactor 110, where they are oxidized or converted into terephthalic acid, while the water contained in the mother solution, cleaning, evaporates and irrigates the distillation column, turning into compressed gas and/or the second liquid phase withdrawn from the column, without exerting significant influence on the water balance during the oxidation process. Transfer the mother liquor purification of the device for separating solids and liquids 230 in the distillation column also reduces the amount of waste liquid, which should be directed to the treatment of liquid effluents, and allows you to regain valuable terephthalic acid by oxidation and provides, in turn, OTB is R to highlight in the mold oxidation reactions 152 and 156.

The exhaust gas of the reaction liquid-phase oxidation of the original para-xylene in the reaction vessel 110 away from the reactor through the opening 116 and served in the thread 111 on the separation in column 330, which, as shown in figure 2, represents a distillation column high pressure with a large number of plates, preferably from about 28-63 theoretical plates, which serves the phlegm through the fluid inlets 336 and 344. The steam flow after oxidation serves in column 330 preferably at a temperature of about 150-225°C and a pressure of approximately 4-21 kg/cm2and virtually no smaller than in the reactor 110. As described above, figure 1 presents the preferred option, in which phlegm fed into the column contains a purification mother liquor, from which the device for separating solids and liquids 230 separates the purified solid terephthalic acid. Column 330 has 80 plates, of which approximately 50-70 located below the input 344, and the rest are above the input phlegmy 344, but below the entry of the second phlegmy 336. Inputs 336 and 344 are arranged so that they are separated by plates corresponding to at least about three theoretical equilibrium stages and preferably about 3-20 such stages. According to preferred variants of the invention, represented in figure 1, phlegm supplied to the column at point 336, before the hat is preferably a liquid condensate, dedicated condensing the second vapor phase high pressure and temperature, selected from the distillation column 330 in the condensing section 350 and directed to the column in the flow 355, while phlegm supplied through the input phlegmy 344 from the stream 233, preferably mother liquor is directed to the column for such use after the separation of solids and liquids and highlight the pure product of liquid-phase oxidation. Supplied in a column of phlegm at the entrance preferably contains approximately 70-85% of the volumetric flow phlegmy added to the column through the inlets 344 and 336.

The first liquid phase enriched solvent liquid - phase oxidation of acetic acid and isolated from the high pressure gas at the inlet to the column 330, together with by-products of the oxidation of para-xylene, such as benzoic acid and p-tolarova acid, dissolved in the liquid phase in the column 330, collect in the bottom of the column. The second liquid phase, which consists mainly of water, but contains small amounts of benzoic acid and p-Truelove acid by-products dissolved in the liquid phase, harvested and removed from the column through the side exit 345. The second high-pressure steam containing water vapor, nscontainerframe components of the exhaust gas after oxidation and by-products of oxidation UKS the red acid, such as methanol and methyl acetate, located primarily in the gas phase, away from the column as a gas to exit through the hole for the head of a shoulder strap 334.

The first liquid phase enriched in acetic acid, formed during the separation in the distillation 330, out of the lower part of the column and preferably to return directly or indirectly in the oxidation reactor 110 in the flow 331. Return the liquid phase oxidation gives the solvent is acetic acid for oxidation reactions and reduces the loss of raw materials, as it allows to turn in the desired intermediate products and by-products of oxidation, condensed from the vapor phase after oxidation, as well as products that are returned in the column together with phlegm containing mother liquor purification. The second liquid phase selected from the column through the side lumen 345, served in the vessel 202 with the cleaning solution in the flow 357 to form a suspension of the crude product and the reaction of the cleaning solution, which is fed to the reactor cleanup 210. Other vessels cleaning and receivers for liquids, which can be directed enriched water, the second liquid phase, include the crystallization vessel 220; this liquid can be used as a pure solvent to replace the reactive cleaning fluid, evaporated into the mould, and device for separating solids and liquids the barb 230 as wash liquid or locking fluid. Liquid condensate is also suitable for use outside of the cleansing stage as wash liquid for filters.

The gas at the outlet of the column through the opening 334 is sent to the device for condensing 350, which, as shown in figure 1, include capacitors 352 and 362 and the separation reservoir 372. Preferably the condensation so that the liquid condensed water stood out at a temperature of about 40-60°C. in one stage. In the variation shown in the figure, the condensation is carried out by indirect heat exchange in the condenser 352 with water at a temperature of about 120-170°C and the resulting condensate is sent to the column 330 in the stream 355 to add to supplied the phlegm 336. Liquid and neskondensirovannyh gas from the condenser 352 served in the capacitor 362 in the stream 361 for condensation by cooling water at about 30-40°C. the Exhaust gas and the liquid from the condenser 362 sent in the stream 363 in the tank 372, which collect liquid condensate containing water, and divert the flow 373, which can be used for other purposes, for example for use as shut-off of liquid or flow to purge. The exhaust from the condenser, the gas under pressure is directed to a flow 375.

Water is used as heat transfer fluid for condensing the second high pressure gas from the distillation columns is s 330, heated by heat exchange in the condenser 350 with the formation of water vapor under pressure, which can be sent to the device utilization of energy, such as steam turbine 450 in process variant, depicted in figure 1. Condensation in two or more successive capacitors using heat transfer fluids with successively lower temperatures allows to obtain water vapor at different pressures, which increases the efficiency of steam at different pressures in accordance with different amounts of heat or energy for operation using water vapor.

Neskondensirovannyh exhaust gas after the condensation collected in the flow 375, contains non-condensable components, such as unspent oxygen after oxidation, nitrogen from the air used as the source of oxygen for oxidation, oxides of carbon from the air and from the reactions of oxidation and trace amounts of unreacted para-xylene and by-products of its oxidation, acetate, and methanol, and methyl bromide, formed from the one used in the oxidation prosteradlo promoter. In the variant represented in the figure, neskondensirovannyh gas contains almost no water vapor due to the almost complete condensation into a liquid condensate, vydeleny is in capacitors.

Neskondensirovannyh exhaust gas from the condenser 350 is under pressure of about 10 to 15 kg/cm2and it can be served directly in the device utilization of the energy or environmental control device to remove corrosive and flammable compounds to energy recovery. As shown in figure 1, neskondensirovannyh gas is first treated to remove unreacted raw materials and traces of solvent is acetic acid and the products of its reactions, remaining in Gaza. Thus, neskondensirovannyh the gas is fed in the flow of 375 in absorber high pressure 380 to absorb para-xylene, acetic acid, methanol and methyl acetate without practical pressure drop. Absorption tower 380 is designed to accept virtually depleted water gas remaining after the condensation, and separation from gas para-xylene, the solvent is acetic acid and the products of their oxidation by contact with one or more liquid reagent from the scrubber. The preferred design of the absorber is shown in the figure, includes a tower 380 with several inside plates or layers or structural gasket (not shown), which create a surface for mass transfer between gas and liquid phases. Inputs (not shown) reagent flush in the absorber flows 381 and 383, respectively, are located in one the or more points in the upper part and in one or more points in the lower part of the tower. The absorber also includes a top opening 382 through which the washed gas under pressure containing non-condensable components of the gas entering the absorber is given in the flow 385, and lower output 384 for selection of flow of liquid acetic acid with one or more components are removed when washing the gas phase, including para-xylene, acetic Isletas, methanol and/or methyl acetate. Bottom liquid removed from the bottom of the tower and served in the reaction vessel 110 for reuse of the selected components.

Gas under pressure, abstracted from capacitor 350 or, as shown in figure 1, from the hole 382 in the absorber high pressure, can be fed into the unit for environmental control 390 for the conversion of organic compounds and carbon monoxide in the gas from the condenser or absorber in carbon dioxide and water. The preferred device for environmental monitoring is the cell catalytic oxidation intended for receiving gas, optional heating to facilitate combustion and gas on the catalyst is stable at high temperature, deposited on a wire mesh or other medium that does not affect the gas flow through the device. The gas of the upper ring of the absorber 380 sent to the environmental management system 390, which includes the device will precede the high heat 392 and cell catalytic oxidation 394. The gas is heated to approximately 250-450°C for pre-heating under pressure of about 10 to 15 kg/cm2and pass into the cell oxidation 394, where organic components and by-products are oxidized in connection safer for the environment.

The oxidized high-pressure gas is directed from the cell catalytic oxidation 394 in the expander 400, which is connected with the generator 420. The energy of the oxidized high-pressure gas is transformed into work in the expander 400 and this work is converted into electrical energy in the generator 420. Advanced gas exits the expander, and it can be released into the atmosphere preferably after irrigation alkaline solution and/or other types of processing for regulating emissions.

1. Method for preparation of aromatic carboxylic acids, including:
the contacting of the feedstock containing at least one substituted aromatic hydrocarbon in which the substituents capable of oxidation to carboxylic groups, with gaseous oxygen in the reaction mixture of liquid-phase oxidation, containing monocarboxylic acid as a solvent and water, in the presence of catalytic compositions intended for oxidation of substituted aromatic hydrocarbons to aromatic carboxylic acids containing at least one heavy metal, CE is the reaction at elevated temperature and pressure, effective to maintain the reaction mixture of liquid-phase oxidation and formation of aromatic carboxylic acid and impurities, containing the reaction by-products dissolved or suspended in the reaction mixture of liquid-phase oxidation and steam with high pressure phase containing the solvent monocarboxylic acid, water and a small amount of starting aromatic hydrocarbon and by-products of the oxidation of the original aromatic hydrocarbon and solvent monocarboxylic acid;
transfer the vapor phase high-pressure, abstracted from the reaction section section division in which the solvent monocarboxylic acid, water and by-products of oxidation are divided by at least one first liquid phase enriched solvent monocarboxylic acid and at least one second liquid phase enriched water, and at least one second steam of the high pressure phase depleted in solvent monocarboxylic acid containing water vapor, so that the by-products of the oxidation of the original aromatic hydrocarbon preferably are in the first liquid phase, and by the oxidation products of the solvent monocarboxylic acid preferably located in the second vapor phase high pressure; and
the removal of sections of division in the Department is lnyh the flow of the first liquid phase, enriched solvent monocarboxylic acid, and a second liquid phase enriched water, which contains less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, and a second vapor phase high pressure, which virtually contains less than 2 wt.% by-products of the oxidation of the original aromatic hydrocarbon.

2. The method according to claim 1, further comprising separating solvent monocarboxylic acid, water and by-products of the oxidation section of the separation stages, including
the supply of steam to the high pressure phase, abstracted from the reaction section, at the first stage of the device for separating and phlegmy on the third stage of the device for separation, so that the steam flow from the first to the second stage and the third stage section division contacted with a countercurrent liquid phlegmy from the third to the second and to the first stage section of the division;
separation of water and solvent monocarboxylic acid in countercurrent vapor phase and liquid phlegmy in the first stage with the formation of the first liquid phase enriched solvent monocarboxylic acid, and
intermediate vapor phase high-pressure - depleted solvent monocarboxylic acid; and
separation of water and by-products in the countercurrent vapor phase and liquid phlegmy in the second stage with the challenge for the internal oxidation products of the substituted aromatic hydrocarbon in the liquid phlegm and the formation of the second intermediate vapor phase high pressure containing water vapor; and
separation of water and by-products of the oxidation of the solvent monocarboxylic acid in countercurrent vapor phase and liquid phlegmy in the third stage, with the formation of a second liquid phase enriched water containing less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, and the second steam high pressure phase containing water vapor and by-products of the oxidation of the solvent monocarboxylic acid and containing less than 2 wt.% by-products of the oxidation of the original aromatic hydrocarbon.

3. The method according to claim 2, additionally including the selection of the partition separating the second liquid phase containing water, virtually free of solvent monocarboxylic acid and by-products of its oxidation.

4. The method according to claim 3, further comprising feeding a second liquid phase selected from section division section purification of aromatic carboxylic acids, so that at least one water-containing liquid in the cleaning sections is a second liquid phase.

5. The method according to claim 2, in which the first stage in the separation device includes theoretical equilibrium stages for the separation of water and solvent monocarboxylic acid in the vapor phase high-pressure received by the section division so that at least about 95 wt.% is astorias - monocarboxylic acid passes into the phlegm in the first stage.

6. The method according to claim 2, in which the phlegm is served on the first stage section of the separation.

7. The method according to claim 6, in which phlegm supplied to the first stage contains Royal cleaning solution, supplied in a section separate from the cleaning section.

8. The method according to claim 2. in which phlegm supplied to the third stage section division contains a liquid condensate of the second vapor phase high-pressure containing water vapor and by-products of the oxidation of the solvent monocarboxylic acid.

9. The method according to claim 1, in which the original aromatic hydrocarbon is para-xylene, solvent monocarboxylic acid is an acetic acid, a second liquid phase, abstracted from section division contains water and less than 5 wt.% the solvent monocarboxylic acid, methanol and methyl acetate, and the second steam high pressure phase contains water vapor without p-Truelove acid.

10. The method according to claim 1, further comprising condensing the second vapor phase high-pressure containing water abstracted from a section of the separation, to form a liquid condensate containing water and exhaust of high pressure gas after the condensation, and the allocation of at least one by-product of the oxidation of the solvent monocarboxylic acid from waste g is at a higher pressure after condensation.

11. The method according to claim 4 or 7, in which the purification of crude aromatic carboxylic acid in the cleaning section consists of the following stages:
(a) formation of a reaction of the cleaning solution containing an aromatic carboxylic acid and impurities dissolved or suspended in a liquid containing water;
(b) contacting the reaction of the cleaning solution containing an aromatic carboxylic acid and impurities dissolved or suspended in a liquid containing water, at elevated temperature and pressure with hydrogen in the presence of a hydrogenation catalyst to form a liquid reaction mixture purification;
(c) isolation of the liquid reaction mixture cleanup containing aromatic carboxylic acid and impurities, solid purified product containing aromatic carboxylic acid with a low concentration of impurities and purification mother liquor;
(d) washing at least one fluid containing water, the resulting solid purified aromatic carboxylic acid selected from liquid purification of the reaction mixture containing the aromatic carboxylic acid impurities and a liquid containing water.

12. Method for preparation of aromatic carboxylic acids, including:
at least one stage of liquid-phase oxidation, comprising the contacting of the feedstock containing at IU is greater least one substituted aromatic hydrocarbon, in which the substituents capable of oxidation to the carboxylic group, with gaseous oxygen in the reaction mixture of liquid-phase oxidation, containing the solvent monocarboxylic acid and water in the presence of catalytic compositions intended for oxidation of substituted aromatic hydrocarbons to aromatic carboxylic acids containing at least one heavy metal section of the reaction at elevated temperature and pressure effective to maintain the reaction mixture of liquid-phase oxidation and formation of aromatic carboxylic acid and impurities comprising by-products of the reactions which are dissolved or suspended in the reaction mixture of liquid-phase oxidation, and steam phase high-pressure water-containing monocarboxylic acid, unreacted substituted aromatic hydrocarbon, oxygen and the reaction by-products; and
at least one purification step comprising contacting with hydrogen at elevated temperature and pressure in the presence of a catalyst containing a catalytically active hydrogenation metal, the reaction of the cleaning solution containing a fluid that contains water and dissolved aromatic carboxylic acid and impurities separated from the reaction mixture of liquid-phase oxidation of at least one with the adiya's liquid-phase oxidation to form a liquid reaction mixture cleaning, containing aromatic carboxylic acid and hydrogenated impurities dissolved in a liquid containing water; and
at least one phase separation off-gas, including the transfer of vapor phase high-pressure, abstracted from sections of the reaction of at least one liquid phase oxidation in the section separation, where it is possible to separate the solvent monocarboxylic acid, water and by-products of oxidation in at least one first liquid phase enriched solvent monocarboxylic acid and at least one second liquid phase enriched water, which is almost free of solvent monocarboxylic acid and at least one second steam of the high pressure phase depleted in solvent monocarboxylic acid containing water vapor, so the by-products of the oxidation of substituted aromatic hydrocarbon preferably fall in the first liquid phase and by-products of the oxidation of the solvent monocarboxylic acid preferably pass into the second steam of the high pressure phase, and the removal of the partition separating the second liquid phase enriched water, which contains less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, and a second vapor phase high-pressure, contains less than 2 wt.% by-products of the Oka is the original aromatic hydrocarbon; and
at least one stage, comprising feeding a second liquid phase enriched in water, selected from sections split at at least one of the operations branch of the exhaust gas in the cleaning section so that the liquid containing the water used by at least one stage of treatment or discharge, separation or washing of the product is a liquid condensate.

13. The method according to item 12, in which at least one cleaning stage includes an operation consisting in dissolving in the water-containing liquid solid product containing aromatic carboxylic acid and impurities, including by-products of oxidation, isolated from the reaction mixture of liquid-phase oxidation after at least one operation of liquid-phase oxidation with the formation of the cleaning solution and a liquid containing water, is a second liquid phase enriched in water and containing less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, remote from the partition dividing at least in the separation off-gas.

14. The method according to item 12, in which at least one cleaning stage includes an operation consisting in suspendirovanie in water-containing liquid solid product containing aromatic carboxylic acid and a lower concentration of impurities, the separation is the R of the liquid reaction mixture cleaning, and water-containing fluid is a second liquid phase enriched in water and containing less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, remote from the partition dividing at least in the separation off-gas.

15. The method according to item 12, in which at least one cleaning stage includes the operation of washing, water-containing liquid solid product containing aromatic carboxylic acid with a low concentration of impurities separated from the liquid reaction mixture cleaning and water-containing fluid is a second liquid phase enriched in water and containing less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, remote from the partition dividing at least in the separation off-gas.

16. The method according to item 12, further comprising at least one stage in which the solid pure form aromatic carboxylic acid with a low concentration of impurities and purification mother liquor separated from the liquid reaction mixture of cleaning at least one cleansing and purification mother liquor served at least one operation of the branch exhaust gas, so that the liquid phlegm supplied in section separation, contained the mother liquor cleanup.

17. The method according to item 12, additional is but involving the condensation of the second vapor phase high pressure containing water abstracted from section division when at least one of the operations branch of the exhaust gas to form a liquid condensate containing water.

18. The method according to 17, further comprising a supply of liquid condensate containing water, a partition dividing at least one of the operations branch of the exhaust gas, so that the liquid phlegm supplied in section separation, contains a liquid condensate containing water.

19. The method according to item 12, further comprising recycling the energy of the second vapor phase high-pressure containing water abstracted from section division when at least one operation of the branch exhaust gas.

20. The method according to item 12, in which the substituted aromatic hydrocarbon in at least one operation of liquid-phase oxidation is para-xylene and the solvent monocarboxylic acid in the liquid-phase oxidation contains acetic acid.

21. The method according to claim 20, in which the second liquid phase, abstracted from section division with at least the branch of the exhaust gas does not contain acetic acid, methanol and methyl acetate, and the second vapor phase high-pressure remote from the partition, separation, does not contain p-Truelove acid.

22. The method according to item 12, further comprising the condensation of the second high pressure steam containing water and less than 2 wt. by-products of the oxidation of the original aromatic hydrocarbon, abstracted from section division when at least one of the operations branch of the exhaust gas to form a liquid condensate containing water and exhaust of high pressure gas from the condensing section and the selection of at least one by-product of the oxidation of the solvent monocarboxylic acid, unreacted aromatic raw materials or combinations thereof from the exhaust of high pressure gas from the condensing section.

23. Method for preparation of aromatic carboxylic acids, including:
(a) contacting the feedstock containing substituted aromatic hydrocarbon in which the substituents capable of oxidation to carboxylic groups, with gaseous oxygen in the reaction mixture of liquid-phase oxidation, containing the solvent monocarboxylic acid and water, and in the presence of catalytic compositions intended for oxidation of substituted aromatic hydrocarbons to aromatic carboxylic acids containing heavy metal section of the reaction at elevated temperature and pressure effective to maintain a liquid reaction mixture and formation of aromatic carboxylic acid and impurities containing by-products of the oxidation of substituted aromatic hydrocarbons which are dissolved or suspended in the reaction mixture of liquid-phase oxidation, and the vapor phase is high pressure, containing the solvent monocarboxylic acid, water, by-products of the oxidation of substituted aromatic hydrocarbon and by-products of the oxidation of substituted aromatic hydrocarbon and solvent monocarboxylic acid;
(b) isolation from the reaction mixture of liquid-phase oxidation of solid product containing aromatic carboxylic acid and impurities, including the reaction by-products;
(c) the dissolution or suspension of the solid product isolated from the reaction mixture of liquid-phase oxidation containing aromatic carboxylic acid and impurities, including by-products of the oxidation of substituted aromatic hydrocarbon, in a liquid containing water at least part of which represents the second liquid phase, selected at stage (g), with the formation of the cleaning solution;
(d) contacting of the cleaning solution at an elevated temperature and pressure with hydrogen in the presence of a hydrogenation catalyst to form a liquid reaction mixture purification;
(e) the allocation of the liquid reaction mixture treatment of solid purified product containing aromatic carboxylic acid with a low concentration of impurities and a liquid mother liquor purification, containing water and by-products of the oxidation source substituted aromatic hydrocarbon, g is tirovannyh derivatives or combinations thereof;
(f) transferring the vapor phase high-pressure stage (a), containing the solvent monocarboxylic acid, water vapor, by-products of the oxidation of substituted aromatic hydrocarbon and by-products of the oxidation of the solvent monocarboxylic acid, in irrigated by phlegm section separation, where you can split the solvent monocarboxylic acid, water and by-products in at least one first liquid phase enriched solvent monocarboxylic acid and at least one second liquid phase enriched water, and at least one second steam of the high pressure phase depleted in solvent monocarboxylic acid containing water vapor, so that the by-products of the oxidation of substituted aromatic hydrocarbons are preferably in the first liquid phase, and by the oxidation products of the solvent monocarboxylic acid are preferably in the second vapor phase high pressure; and
(g) deleting from section separate individual streams of the first liquid phase enriched solvent monocarboxylic acid, and a second liquid phase enriched in water and containing less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, and a second vapor phase high-pressure, contains less than 2 wt.% by-products of oxidized is my initial aromatic hydrocarbon;
(h) feeding a second liquid phase enriched water removed from the section of the separation stage (g), at least one of stages (C), (d) or (e), so that the liquid containing water, at least one of the steps (C), (d) or (e) represents the second liquid phase.

24. The method according to item 23, further comprising feeding the mother liquor cleanup allocated to stage (e), stage (f), so that the liquid phlegm, supplied in a section of the separation stage (f), contains the mother liquor cleanup.

25. The method according to item 23, further comprising the separation of liquid condensate containing water from the second vapor phase high pressure that was abstracted from a section of the separation stage (g).

26. The method according to item 23, comprising a supply of liquid condensate containing water, selected from the second vapor phase high-pressure stage (f), so that the liquid phlegm, supplied in a section of the separation stage (f), contains a liquid condensate.

27. The method according to p, including feeding the mother liquor cleanup allocated to stage (e), stage (f), so that the liquid phlegm, supplied in a section of the separation stage (f), contains the mother liquor cleanup.

28. The method according to item 27 in which the liquid phlegm containing liquid condensate, served in the upper part of the section of the separation.

29. The method according to p, in which the liquid phlegm containing uterine rest the R cleaning served in the lower part of the section of the separation.

30. The method according to item 27 in which the liquid phlegm containing mother liquor purification, served in the lower part of the section of the separation.

31. The method according to item 30, in which the second liquid phase which was deleted from the section of the separation stage (g), taken from a section of the separation of the intermediate section between the upper and lower parts.

32. The method according to p. 25, further comprising recycling the energy of the second vapor phase high-pressure containing no by-products of the oxidation of the original aromatic hydrocarbon, abstracted from section separation stage (g).

33. The method according to item 23, further comprising recycling the energy of the second vapor phase high-pressure, abstracted from section separation stage (g).

34. The method according to p, in which the energy is utilized in the form of work.

35. The method according to p, in which the energy is utilized in the form of heat.

36. The method according to any of PP-35, in which the substituted aromatic hydrocarbon is para-xylene, and solvent monocarboxylic acid is an acetic acid.

37. The method according to any of PP-35, in which the second liquid phase is removed from a section of the separation stage (g), does not contain acetic acid, methanol and methyl acetate, and the second vapor phase high-pressure, abstracted from section separation, does not contain p-tol the sludge acid.

38. A device for the separation of components of exhaust from the reactor gas, formed during the extraction of aromatic carboxylic acids by liquid-phase oxidation of a raw material of the substituted aromatic hydrocarbon in the liquid reaction mixture comprising a closed vessel in the form of columns with limited internal volume,
at least one lower gas inlet for receiving and feed to the first stage of the fractionation section of the head of a ring-steam high-pressure phases, abstracted from the reaction vessel for liquid-phase oxidation source substituted aromatic hydrocarbon with gaseous oxygen in a liquid reaction mixture containing the solvent monocarboxylic acid and water, in the conditions of maintaining the liquid reaction mixture and formation of the ring-steam high pressure phase containing vapors of solvent monocarboxylic acid and water formed in the reaction vessel;
the fractionation section in the internal volume of the vessel for contacting gas and liquid phases in countercurrent through several theoretical equilibrium stages, including
the first part, where you can split water and solvent monocarboxylic acid in the vapor phase high pressure in contact with a countercurrent of phlegmy containing components phlegmy obtained from an intermediate stage section FR is klonirovania, so the first liquid phase enriched solvent monocarboxylic acid, take away the phlegm and forms a first intermediate vapor phase depleted in solvent monocarboxylic acid containing water vapor, and the first part is connected by a thread with the intermediate part of the fractionation section for receiving therefrom phlegmy and feed back the first intermediate vapor phase and contains a device for the direction of phlegmy through which the first liquid phase is sent to a reservoir for fluid; and
intermediate part, where you can split water and by-products of liquid-phase oxidation of a raw material - substituted aromatic hydrocarbon in the first intermediate vapor phase by contact with a countercurrent of phlegmy containing components phlegmy obtained from the upper part of the device for separation, so that by-products of the oxidation of the original aromatic hydrocarbon selected in the phlegm and forms the second intermediate steam high pressure phase containing water vapor, and the intermediate part is connected by a thread with the upper part of the fractionation section for receiving therefrom phlegmy and feeding back the second intermediate vapor phase; and
the upper part, where you can almost divide the water and by-products of liquid-phase oxidation of solvent monocarboxylic acid, at least one is th second intermediate vapor phase and in the phlegm, supplied to the upper part, in contact with a countercurrent of phlegmy, so that the second liquid phase containing water, which contains less than 5 wt.% the solvent monocarboxylic acid and by-products of its oxidation, taken in the phlegm and forms a second steam high pressure phase containing water vapor and by-products of the oxidation of the solvent monocarboxylic acid and less than 2 wt.% by-products of the oxidation of the original aromatic hydrocarbon, with the upper part of the device includes in its lower portion for collecting at least part of phlegmy, which removes the second liquid phase;
the reservoir for the liquid to receive from the first part of the section of the fractionating phlegmy, which removes the first liquid phase; and
at least one outlet for fluid communication with a reservoir for liquid to remove fluid from the apparatus; and
at least one inlet for liquid to supply phlegmy in the upper area of the upper part of the fractionation section;
at least one inlet for liquid to flow of the liquid phlegmy in the upper area of the lower part of the fractionation section; and
at least one outlet for fluid communication with the collector for removal from the device at least part of phlegmy, which removes the second liquid phase.

39. The device according to § 38, in which the fractionation section comprises 20-80 is eroticheskie equilibrium stages.

40. The device according to § 38, in which the first part of the section of the fractionation can separate water and solvent monocarboxylic acid in the vapor phase high pressure, so that at least about 95 wt.% the solvent monocarboxylic acid are removed in the phlegm.

41. The device according to § 38, in which at least one output in communication with the collector and at least one inlet for supplying phlegmy in the upper area of the lower part of the fractionation section is divided 1-10 theoretical equilibrium stages.

42. The device according to § 38, in which at least one output in communication with the collector and at least one inlet for supplying phlegmy in the upper area of the upper part of the fractionation section is divided 1-10 theoretical equilibrium stages.

43. Device according to any one of p-42, made in the form of at least one distillation column.

44. The device according to item 43, further comprising a reaction vessel for liquid-phase oxidation of a raw material - substituted aromatic hydrocarbon with gaseous oxygen in a liquid reaction mixture containing the solvent monocarboxylic acid and water, in the conditions of maintaining the liquid reaction mixture and education in the reaction vessel in the ring-steam high pressure phase containing vapors of solvent monocarboxylic acid and water, and the reaction is Oud has at least one hole for drainage of the head of a shoulder strap vapor phase high pressure associated thread at least one bottom gas inlet for receiving and direction of the head of a shoulder strap vapor phase high pressure to the first stage of the fractionation section.

45. Device according to any one of p-42, additionally comprising the reaction vessel liquid-phase oxidation of a raw material - substituted aromatic hydrocarbon with gaseous oxygen in a liquid reaction mixture containing the solvent monocarboxylic acid and water, in the conditions of maintaining the liquid reaction mixture and education in the reaction vessel in the ring-steam high pressure phase containing vapors of solvent monocarboxylic acid and water, and the reaction vessel has at least one hole for drainage of the head of a shoulder strap vapor phase high pressure associated with the flow of the at least one bottom gas inlet for receiving and direction of the head of a shoulder strap vapor phase at high pressure the first stage of the fractionation section.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: terephthalic acid production method involves a step A) for oxidising paraxylene to terephthalic acid with air in the presence of a liquid reaction phase kept at temperature between 180°C and 230°C, where the liquid reaction phase contains paraxylene, acetic acid, water and a catalyst composition, where amount of water is 5-12% of the weight of acetic acid, the mass ratio of acetic acid to paraxylene is not less than 30:1 and must be such that 15-50% of reacted terephthalic acid is present in solid form at oxidation temperature and the catalyst composition contains cobalt, manganese and bromine combined with at least one element selected from a group consisting of zirconium and hafnium, where atomic ratio Co:Mn:Br is in the range 1:0.2-1.0:1.1-2.7, and atomic ratio of cobalt to elements selected from a group consisting of zirconium and hafnium is equal to 1:0.03:0.3, where total mass of Co and Mn is equal to 100-500 mg per 1 kg of the liquid reaction phase; and B) extraction of terephthalic acid through crystallisation at temperature between 150°C and 80°C.

EFFECT: method gives terephthalic high purity without a secondary purification step currently used in practice.

3 cl, 19 ex, 3 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of purifying carboxylic acid from a mixture which contains one or more carboxylic acids selected from a group consisting of terephthalic acid, isophthalic acid, orthophthalic acid and their mixtures, and also contains one or more substances selected from a group consisting of carboxybenzaldehyde, toluic acid and xylene. The method involves: bringing the mixture into contact with a selective solvent for crystallisation at temperature and in a period of time sufficient for formation of a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation without complete dissolution of the complex salt of carboxylic acid; extraction of the complex salt and decomposition of the complex salt in the selective solvent for crystallisation in order to obtain free carboxylic acid. The mixture containing unpurified carboxylic acid is brought into contact with the selective solvent for crystallisation in order to form a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation. The complex salt is extracted and, if desired, processed for extraction of free carboxylic acid.

EFFECT: methods are especially suitable for purifying aromatic dibasic carboxylic acids such as terephthalic acid, and also enables reduction of the degree of contamination of phthalic acids with carboxybenzaldehyde isomers.

22 cl, 3 tbl, 1 dwg, 3 ex

FIELD: process engineering.

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

EFFECT: higher efficiency.

44 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing highly pure terephthalic acid which involves the following steps: (a) an oxidation reaction, where p-xylene is oxidised in an acetic acid solution in the presence of a catalyst to form terephthalic acid, (b) obtaining crystals of crude terephthalic acid, where the suspension containing the precipitate of the obtained terephthalic acid is separated into a solid phase and a liquid to obtain crystals of crude terephthalic acid, (c) hydrogenation step, where crystals of crude terephthalic acid are dissolved in water to form an aqueous solution which is hydrogenated, (d) crystallisation of highly pure terephthalic acid, where terephthalic acid is crystallised from the hydrogenated aqueous solution to form a suspension of highly pure terephthalic acid, (e) obtaining crystals of highly pure terephthalic acid, where the suspension of highly pure terephthalic acid is separated into a solid phase and a liquid to obtain crystals of highly pure terephthalic acid and a primary mother solution, and (f) extraction of p-toluic acid from the primary mother solution and taking it to the oxidation reaction step, where the p-toluic acid extraction step includes the following steps: (I) adsorption step, where primary or secondary mother solution, obtained by cooling the primary mother solution in order to separate the solid phase and liquid, is fed in form of treated liquid into an adsorption column filled with an adsorption agent, where the p-toluic acid breakthrough time is greater than that of benzoic acid, for adsorption of p-toluic acid and benzoic acid from the treated liquid on the adsorption agent, (II) cutting supply of the treated liquid into the adsorption column for at a certain moment in time when concentration of benzoic acid in the effluent from the adsorption column reaches at least 10% of the concentration of benzoic acid in the treated liquid, (III) desorption step, where a desorption agent in form of acetic acid, methylacetate or their mixture is fed into the adsorption column for desorption of the adsorbed p-toluic acid and (IV) circulation step, where p-toluic acid contained in the desorption agent flows from the adsorption column and taken to the oxidation reaction step.

EFFECT: design of a method of obtaining highly pure terephthalic acid through selective extraction of p-toluic acid from waste water currently released, and use of the waste water as raw material for producing terephthalic acid.

19 cl, 6 dwg, 5 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to liquid-phase catalytic oxidation of an aromatic compound and a reactor-type bubble column. A stream of oxidising agent which contains molecular oxygen and a stream of starting material containing the oxidised compound are fed into the reaction zone of the bubble column reactor. As a result of oxidation, a solid-phase product from at least approximately 10 wt % of the oxidised compound is obtained. At least a portion of the reaction medium containing the solid-phase product is taken from the reaction zone through one or more openings lying at a higher level than the inlet zone of at least a portion of the molecular oxygen into the reaction zone. Average gas flow rate per unit cross section of the stream at half the height of the said reaction medium is kept equal to at least approximately 0.3 m/s. The proposed installation has a bubble column reactor with a perforated shell, a reaction medium container and a channel designed for carrying spent reaction medium into the container.

EFFECT: product can be extracted and purified using methods which are cheaper than those which can be used if the acid is obtained via a high-temperature oxidation method.

32 cl, 35 dwg, 7 tbl, 13 ex

FIELD: chemistry.

SUBSTANCE: invention relates to liquid-phase catalytic oxidation of an aromatic compound and to the obtained crude terephthalic acid. Oxidation is carried out in a bubble column reactor which ensures a highly efficient process at relatively low temperature. Particles of the obtained terephthalic acid, which contains approximately less than 100 parts weight/million of 2,6-dicarboxyfluorenone, have transmission factor at 340 nm (%T340) greater than approximately 25%, additionally contains approximately less than 12 parts weight/million of 4,4-dicarboxystilbene and/or contains approximately less than 400 parts weight/million of isophthalic acid. Particles of the obtained terephthalic acid, characterised by average size ranging from approximately 20 to approximately 150 micrometres, are dissolved in tetrahydrofuran for one minute to concentration of a least approximately 500 parts/million and/or is characterised by average BET surface area greater than approximately 0.6 m2/g.

EFFECT: product can be extracted and purified using methods which are cheaper than those which can be used if the acid is obtained via a high-temperature oxidation method.

37 cl, 36 dwg, 5 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: method involves, for example: (a) evaporation of said oxidised discharge stream, containing terephthalic acid, metallic catalyst, impurities, water and solvent, in the first zone of an evaporator to obtain a vapour stream and a concentrated suspension of the discharge stream; and (b) evaporation of the said concentrated suspension of the discharge stream in the second zone of the evaporator to obtain a stream rich in solvent and a high-concentration suspension of the discharge stream, where the said second zone of the evaporator has an evaporator operating at temperature ranging from 20°C to 70°C, where from 75 to 99 wt % of the said solvent and water is removed by evaporation from the said oxidised discharge stream at step (a) and (b); (c) the said high-concentration suspension of the discharge stream is filtered in a zone for separating solid products and liquid to form a filtered product and a mother liquid; (d) washing the said filtered product using washing substances fed into the said zone for separating solid products and liquid to form a washed filtered product and washing filtrate; and dehydration of the said filtered product in the said zone for separating solid products and liquid to form a dehydrated filtered product; where the said zone for separating solid products and liquid has at least one pressure filtration device, where the said pressure filtration device works at pressure ranging from 1 atmosphere to 50 atmospheres; (e) mixing water and optionally extractive solvent with the said mother liquid and with all of the said washing filtrate or its portion in the mixing zone to form an aqueous mixture; (f) bringing the extractive solvent into contact with the said aqueous mixture in the extraction zone to form a stream of extract and a purified stream, where the said metallic catalyst is extracted from the said purified stream.

EFFECT: improved method of extracting metallic catalyst from an oxidised discharge stream obtained during production of terephthalic acid.

36 cl, 3 dwg, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of preparing a dry residue of aromatic dicarboxylic acid containing 8-14 carbon atoms, suitable for use as starting material for synthesis of polyester, where the said method involves the following sequence of stages, for example: (a) oxidation of aromatic material in the oxidation zone to obtain a suspension of carboxylic acid; (b) removal of impurities from the suspension of aromatic dicarboxylic acid in the liquid-phase mass-transfer zone where at least 5% liquid is removed, with formation of a residue or suspension of aromatic dicarboxylic acid, and a stream of mother solution, where the liquid-phase mass-transfer zone includes a device for separating solid substance and liquid; (c) removal of residual impurities from the suspension or residue of aromatic dicarboxylic acid obtained at stage (b) in the zone for countercurrent washing with a solvent to obtain a residue of aromatic dicarboxylic acid with the solvent and a stream of mother solution together with the solvent, where the number of steps for countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, and the said solvent contains acetic acid, (d) removal of part of the solvent from the residue of aromatic dicarboxylic acid together with the solvent obtained at stage (c) in the zone for countercurrent washing with water to obtain a residue of aromatic dicarboxylic acid wetted with water and a stream of liquid by-products together with the solvent/water, where the number of countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, where stages (b), (c) and (d) are combined into a single liquid-phase mass-transfer zone, and directing the residue of aromatic dicarboxylic acid wetted with water directly to the next stage (e), (e) drying the said residue of aromatic dicarboxylic acid wetted with water in the drying zone to obtain the said dry residue of aromatic dicarboxylic acid suitable for synthesis of polyester, where the said residue wetted with water retains the form of residue between stages (d) and (e).

EFFECT: design of an improved version of the method of preparing dry residue of aromatic dicarboxylic acid.

21 cl, 4 dwg

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

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: process engineering.

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

EFFECT: higher efficiency.

44 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention 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

The invention relates to a method for the isomers of phthalic acid with a high degree of purity of the three-stage liquid-phase oxidation of xylene isomers, which improves the efficiency of the process and to improve the quality of the target product through the application of new catalytic systems that can improve the response speed limiting stages, namely, the conversion speed isomers Truelove acid and carboxybenzaldehydes (KBA) in target products at moderate temperatures, as well as to achieve a rapid, almost instantaneous mixing of the reactants in the reaction zone with an ideal distribution in the reaction space of the nutrient mixture, which comes in the form of restricted flows (submerged in liquid jets) with a high degree (6-30 m/s) countercurrent with respect to the direction of the circular rotation of the reaction mixture

The invention relates to a method for isomers benzylcarbamoyl acid with a high degree of purity, and this method does not require the cleanup phase hydrogenation method

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of purifying carboxylic acid from a mixture which contains one or more carboxylic acids selected from a group consisting of terephthalic acid, isophthalic acid, orthophthalic acid and their mixtures, and also contains one or more substances selected from a group consisting of carboxybenzaldehyde, toluic acid and xylene. The method involves: bringing the mixture into contact with a selective solvent for crystallisation at temperature and in a period of time sufficient for formation of a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation without complete dissolution of the complex salt of carboxylic acid; extraction of the complex salt and decomposition of the complex salt in the selective solvent for crystallisation in order to obtain free carboxylic acid. The mixture containing unpurified carboxylic acid is brought into contact with the selective solvent for crystallisation in order to form a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation. The complex salt is extracted and, if desired, processed for extraction of free carboxylic acid.

EFFECT: methods are especially suitable for purifying aromatic dibasic carboxylic acids such as terephthalic acid, and also enables reduction of the degree of contamination of phthalic acids with carboxybenzaldehyde isomers.

22 cl, 3 tbl, 1 dwg, 3 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 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: 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

Up!