Method of producing acrylic acid

FIELD: chemistry.

SUBSTANCE: conducting heterogeneously catalysed gas-phase partial oxidation of at least one corresponding starting compound with three carbon atoms on catalysts in a solid aggregative state at high temperature with molecular oxygen enables to obtain a gaseous mixture of products containing acrylic acid, water vapour and secondary components; if necessary, temperature of said mixture is lowered by direct and/or indirect cooling, after which said mixture is fed into a condensation column equipped with efficiently separating elements, wherein said mixture rises by itself along said column with simultaneous flow of fractional condensation. Through a first side outlet, which lies above the point of feeding the gaseous mixture of reaction products into the condensation column, crude acrylic acid poor in water and secondary components is output from the condensation column as the end product; through a second liquid phase outlet lying above the first side outlet, acid water containing acrylic acid and secondary components is output from the condensation column; a residual gaseous mixture containing secondary components which boil at a lower temperature than water is output from the top part of the condensation column; still liquor which contains acrylic acid, as well as byproducts and secondary components which boil at higher temperature than acrylic acid are output the bottom of the condensation column; part of the amount of the collected acid water as it is and/or after cooling is returned into the condensation column as reflux, and crude acrylic acid is optionally subjected to additional treatment using at least another thermal separation method, and, if necessary, part of the amount of collected acid water is added to acrylic acid before additional crystallisation treatment, where acrylic acid contained in at least part of the amount acid water which is not returned into the condensation column is transferred from the acid water to an organic solvent through extraction carried out by said solvent, which is accompanied by formation of an organic extract containing acrylic acid, from which acrylic acid is further separated by stripping thereof with a first stripping gas, wherein the first stripping gas containing acrylic acid is returned into the condensation column, and/or acrylic acid contained in the first stripping gas is transferred into an aqueous solution of a metal hydroxide or the formed first stripping gas which contains acrylic acid is used as a second stripping gas in order to strip acrylic acid contained in the still liquor output from the condensation column, and wherein the formed second stripping gas containing acrylic acid is returned into the condensation column and/or acrylic acid contained in the second stripping gas is transferred into an aqueous solution of a metal hydroxide.

EFFECT: improved method.

21 cl, 6 ex

 

The present invention relates to a method for producing acrylic acid according to which way carried out at elevated temperature heterogeneously catalyzed gas-phase partial oxidation with molecular oxygen of at least one of the corresponding starting compound with three carbon atoms in the solid aggregate state catalysts receive a gas mixture of products containing acrylic acid, water vapor and side components, the temperature of this mixture, if necessary, reduced by direct and/or indirect cooling, after which this mixture is sent to feature effectively separating the elements of the condensation column, along which she rises while passing fractional condensation, and through the first side the selection above the place of supply of the gas mixture of the reaction products of the condensation column, the condensation column deduce depleted water and side components of the crude acrylic acid as the target product, through above the first side of the second selection (preferred side) sampling of the liquid phase from the condensation column display containing acrylic acid and side components of the acidic water from the upper part of the condensation colonialidad residual gas mixture, containing side components, which are at atmospheric pressure boil at a lower temperature than water, from a cube condensation column deduce cubic liquid containing acrylic acid and by-products and side components, which are at atmospheric pressure boil at lower temperatures than acrylic acid, partial extraction quantity of acidic water as such and/or after cooling return in the condensation column as phlegmy and crude acrylic acid optionally subjected to additional cleaning at least one other method of thermal separation.

Acrylic acid is an important intermediate used, for example, to obtain polymer dispersions (optionally also in the form of esters of acrylic acid with alkanols), and super absorbent water polymers.

Acrylic acid can be obtained, in particular, by carried out at elevated temperature heterogeneously catalyzed gas-phase partial oxidation of corresponding compounds with three carbon atoms with molecular oxygen in the solid aggregate state catalysts, and under the specified parent compounds primarily involve chemical compounds, which can formally receive the th recovery of acrylic acid (known parent compounds of this type are, for example, propane, propylene, acrolein, propionic aldehyde and propionic acid, but under them include, for example, compounds such as glycerin, acrylic acid which can be obtained, for example, by heterogeneously catalyzed oxidative dehydration in the gas phase; see, for example, European patent application EP AND 1710227, as well as international application WO 06/114506 and WO 06/092272).

While the above source gases, generally diluted with inert gases, such as nitrogen, carbon dioxide, saturated hydrocarbons and/or water vapor, and then at elevated temperatures, and optionally at elevated pressure in a mixture with molecular oxygen is passed through the catalysts based on mixed metal oxides (e.g., transition metals), exposing the oxidative transformation in the gas mixture of the reaction products containing acrylic acid, water and also unwanted side products, such as furfural, benzaldehyde, acetone, formaldehyde, maleic anhydride and the like, from which you then need to allocate acrylic acid (to denote products that are different from water vapor inert diluting gases, as well as inhibitors of polymerization usually added during the implementation processes of extraction acrylic is howling acid, according to the present invention use the General term "side components").

When heterogeneously catalyzed gas-phase partial oxidation of propionic aldehyde and/or propionic acid molecular oxygen is at least a partial oxidative dehydrogenation.

From German patent applications DE A 19924533 and DE A 19924532, international application WO 01/77056, German patent applications DE A 10156016, DE A 10243625, DE A 10223058 and DE A 10235847, international applications WO 2004/035514 and WO 00/53560, and from German patent application DE A 10332758 known methods for producing acrylic acid specified in the beginning of the description of the type according to which the basic allocation of crude acrylic acid is carried out by fractional condensation of the product gas mixture heterogeneously catalyzed gas-phase partial oxidation. The term "crude acrylic acid" is used to emphasize the fact that under the first side selection mean not pure acrylic acid, and the mixture, which in addition to the acrylic acid content, calculated on the total weight, usually more than 50 or 60 wt. -%, often more than 70 or 80 wt. -%, in many cases, more than 90% of the mass. and often more than 95% of the mass. or above) are water and side components, such as lower aldehydes (e.g., furfural, acrolein, b is soldered), lower carboxylic acids (e.g. acetic acid, propionic acid, formic acid and so on. In any case, the total water content and side components in the crude acrylic acid compared to the concentration of the acrylic acid is less than in the gas mixture of the products of gas-phase partial oxidation, and therefore you can say that crude acrylic acid is depleted by the sum of these components compared with the specified gas mixture, though some of them may be present in the crude acrylic acid in a relatively higher concentration.

The degree of purity emitted above methods crude acrylic acid sometimes is already high enough, so that it can be used for certain purposes, such as to obtain products of esterification or for the synthesis of polymers by radical polymerization. However, in many cases, a dedicated crude acrylic acid is subjected to processing at least one other method of thermal separation to isolate it more pure acrylic acid, which has a higher content of acrylic acid (% wt.) compared to the crude acrylic acid, and therefore, meets the requirements for the degree of purity used in the relevant field of acrylic acid./p>

Under thermic mean separation processes, whereby when the supply or discharge (usually thermal) energy physically form at least a two-phase system, and because existing between the phases of temperature and concentration gradient is the transfer of heat and mass transfer, which ultimately leads to the necessary separation and extraction.

Methods of thermal separations are often implemented in distillation columns with effectively separating inline elements, and at least two of the above material phase move in these columns, generally towards each other (counter-current). In many cases one of the two material phases is the gaseous phase, which moves in a distillation column, as a rule, from the bottom up, while the other is in the liquid phase, which moves in a distillation column, as a rule, from top to bottom. However, in principle at least two material phases can be liquid (for example, in the case of extraction), respectively, solid and liquid (for example, in the case of crystallization) or, respectively, solid and gaseous (for example, in the case of adsorption).

An example of a practical embodiment of the methods of thermal separation, when at least on the at of the two material phases is liquid, and the other gas is rectification, in accordance with which rising in the distillation column vapor phase moves towards the descending liquid phase and an inverse absorption desorption process, in accordance with which dissolved in the liquid phase, the gas removed from it by reducing the pressure above the liquid phase, increasing its temperature and/or transmission through it of the gas phase, and in the latter case, the desorption is also called Stripping. In addition, the methods of thermal separation is the absorbance, according to which rising in the distillation column, the gas moves in a generally countercurrent with respect to at least one liquid downward absorbent and fractional condensation of the gas mixture, which is accompanied by the formation of gas and liquid phases. A particularly suitable method of thermal separation used for additional purification of crude acrylic acid is an additional crystallization purification (crystallization).

A disadvantage of the known methods from the main selection crude acrylic acid by fractional condensation of the product gas mixture heterogeneously catalyzed gas-phase partial oxidation of at least one starting compound with three carbon atoms is more the education of the so-called acidic water, where are acrylic acid and side components. The water content of the acidic water, as a rule, is more than or equal to 50 wt. -%, often more than or equal to 60 wt. -%, in many cases, more than or equal to 70% of the mass. and often more than or equal to 80 wt. -%, moreover, under water, generally involve the reaction water, and dilution water (water vapor used for carrying out gas-phase partial oxidation in an inert dilution gas).

In addition to water in acidic water contains acid side components, such as propionic acid, acetic acid and formic acid, and acrylic acid, and therefore the pH of acidic water is less than 7 (the total content different from the acrylic acid side-acid components in terms of mass of acidic water, as a rule, is less than or equal to 10 wt. -%, in particular less than or equal to 5 wt. -%).

The content of acrylic acid in the acidic water is usually in the range from 4 or 5% of the mass. up to 15% of the mass. and often is about 10% of the mass. The lack of ways from the main selection of acrylic acid from product gas mixture heterogeneously catalyzed gas-phase partial oxidation, featured in the above-cited prior art, is that all non-refundable in the distillation column cislo the water, contains acrylic acid, sent for incineration (see primarily from German patent application DE A 10243625 and DE A 10332758, as well as international application WO 2004/035514).

This circumstance should be considered as a disadvantage, because the burning acidic water causes, for example, the reduction of yield of acrylic acid as the target product.

Taking into account the above prior art, the present invention was based on the task to provide an improved method of obtaining acrylic acid, is primarily characterized in that it allows for increased outputs of acrylic acid without significantly reducing its purity.

The specified task according to the invention solved through a method for producing acrylic acid according to which way carried out at elevated temperature heterogeneously catalyzed gas-phase partial oxidation with molecular oxygen of at least one of the corresponding starting compound with three carbon atoms in the solid aggregate state catalysts receive a gas mixture of products containing acrylic acid, water vapor and side components, the temperature of this mixture, if necessary, reduced by direct cooling (i.e. cooling, which is implemented by directly entering the frame contact with the cooling fluid) and/or indirect cooling, then this mixture is sent to feature effectively separating the elements of the condensation column, along which she rises while passing fractional condensation, and through the first side selection above the place of supply of the gas mixture of the reaction products of the condensation column, the condensation column deduce depleted water and side components of the crude acrylic acid as the target product, through above the first side of the second selection the selection of the liquid phase from the condensation column display containing acrylic acid and side components acidic water (the second selection is preferably the side with all the embodiments of the method we refer it to the side selection acidic water), from the top of the condensation column output residual gas mixture containing side components, which are at atmospheric pressure boil at a lower temperature than water, from a cube condensation column deduce cubic liquid containing acrylic acid and by-products and side components boiling at a higher temperature than acrylic acid, partial extraction quantity of acidic water as such and/or after cooling in return condensation to the Onna as phlegmy, and crude acrylic acid optionally subjected to additional cleaning at least one other method of thermal separation, characterized in that the acrylic acid contained in at least a partial amount of non-refundable in the condensation column acidic water, transferred to an organic solvent by running this solvent extraction, followed by formation containing acrylic acid organic extract, from which the acrylic acid in the future, allocate at least one method of thermal separation, with selected acrylic acid back into the condensation column and sent for further purification of crude acrylic acid and/or transferred to an aqueous solution of the hydroxide of the metal.

According to the invention preferably at least 25 wt. -%, better at least 50 wt. -%, even better, at least 75% of the mass. and preferably, the entire quantity of the non-refundable in the condensation column sour water is subjected carried out according to the invention the extraction and further processing.

To implement necessary according to the invention the extraction is in principle possible to use any known extraction equipment suitable for the extraction of liquid fluid. Such equipment must ensure who is very useful for the formation of a large surface interface and thin distribution of droplets in the continuous phase, as well as the option of quick and full separation of the phases after the established mass transfer.

In the most simple embodiment, as an extraction device, you can use the mixer (for example, a container with a mixer or static mixer in combination with a separator (for example, a settling tank). While in principle you can use any common mixer. Examples of suitable mixers are disk stirrers, impeller stirrers, paddle stirrers, frame stirrers, postoloprty stirrers, anchor stirrers, propeller mixers, spiral mixers and multi-pulse countercurrent agitators. The mixer can also be stacked, that is, one axis may be located one above the other few mixing elements. Preferred is the use of bunk blade mixers. As a sump tank in principle you can use any normal capacity. Preferred is a horizontal settling tank. Such extraction device can be operated continuously or intermittently, and in the latter case, you can refuse the use of a settling tank and to carry out the separation of the phases in the vessel with stirrer. Subject to extraction of the substance passes into the absorption of its phase will smusic the Le, while the separation of the respective phases under the action of gravity occurs in the separator. In the case of continuous mode efficiency occurring in the settling tank separation of flowing the product at the heavy and light phase can be improved through the use of built-in elements arranged across the direction of flow. This is suitable in principle are all commonly used built-in items, such as perforated sheets, plates, nozzles and/or bulk materials. The preferred bulk materials are rings, spirals, saddles, rings process, the ring of Into, ring Poll, seat Burleigh, saddle Intalox, materials, Top-Pak, and so forth, or braided materials. Especially preferred are perforated sheets in combination with bulk materials. Typical residence time in the settling tank is from 0.05 to 2 hours.

Several interconnected nodes, including the mixer and the separator form a cascade. The nodes of the cascade can be connected to each other for operation of the countercurrent, co-current or cross-current.

Carried out according to the invention the extraction with a production-technical point of view it is expedient to perform in the extraction column, is supplied efficiently separating aircraft is rainnie elements. The relatively heavy phase is introduced into the extraction column at the top, while the relatively lighter phase flows into it from below. These phases are moving in the extraction column countercurrent. Extraction columns in principle similar to the columns used for carrying out countercurrent distillation (rectification). Thus, extraction columns, suitable for carrying out the invention the extraction process, may have a known structure and contain the usual built-in items.

Potentially suitable may be the extraction columns, functioning as a flow of energy, and without energy supply. Extraction columns with embedded elements in the form of nozzles (primarily structured accordingly ordered) and/or bulk materials can function as a flow of energy, and without energy supply. While the preferred bulk materials are rings, spirals, saddles, rings process, the ring of Into, ring Poll, seat Burleigh, saddle Intalox, materials, Top-Pak, and the like. Nozzles, especially suitable to be used according to the invention the extraction columns are, for example, the products of the company Julius Montz GmbH (D-40705 Hilden), in particular, such as nozzle Montz-Pak B1-350. Preferably use the Ute perforated structured nozzles from the special sheet steel. The Packed column with structured packings known in the art and described, for example, in Chem. - Ing. Tech., 58 (1986), Nr.1, SS-31, as well as in Technical Rundschau Sulzer, 2/1979, 49 and following (Gebruder Sulzer Aktiengesellschaft, CH-Winterthur). Also suitable are also extraction columns with embedded elements in the form of plates, and it is necessary to distinguish between columns with pulsating sieve plates and columns, equipped with sieve plates with cross-current. In the case of columns with pulsating sieve plates both phases pass through is made in the plates through holes, which, as a rule, possess a round shape. The lighter phase with the ripple progress upward passes through the mesh plate in the upward direction, the heavier phase with the ripple progress down passes through corresponding holes in the downward direction. Similarly, there are column Carr, but in this case, the pulsation of the fluid is absent, and alternately move up and down the mesh plates. Extraction columns with pulsating sieve plates are preferred. In contrast to similar columns in the case of columns, equipped with sieve plates with cross-current, continuous phase flows from one plate to another through the drain pipe, while the dispersed phase proj the leads through the holes of the sieve plates due to the difference of densities (used in this description to denote mass transfer plates similar to that shown in the German patent application DE A 10332758).

For the ongoing according to the invention the extraction of acidic water, as a rule, enough from 1 to 10 theoretical plates. According to the invention under a theoretical plate (or theoretical stage) in the most General case, the mean unit volume distillation columns with integrated elements ensuring the efficient separation by thermal separation, which contributes to the concentration of the substance in accordance with thermodynamic equilibrium. Thus, the term "theoretical plate" was equally applicable for the extraction columns with mass transfer plates, and extraction columns with nozzles and/or nozzle bodies.

If for carrying out the invention method uses extraction column, a relatively heavier phase in the production-technically it is advisable to submit to the column by means located in the upper part of the distribution manifold, providing the most uniform distribution of this phase over the entire cross section of the column. The introduction of relatively lighter phase in the column in the production and technical terms should be carried out through located in the lower part of the column distribution manifold. In accordance with this thinner is the second phase inside the column rises, while the heavier phase is omitted. If the lighter phase is dispersed (that is, it is in the form of drops), phase separation occurs in the upper part of the column, whereas in the case of dispersion heavier phase separation of phases occurs in the cube column. The optimal diameter (longitudinal size) drops in both cases corresponds to the interval from 1 to 10 mm, preferably from 2 to 5 mm.

According to the invention the extracting agent preferably has a higher boiling point than acrylic acid (respectively at atmospheric pressure), because it generally facilitates the subsequent allocation of acrylic acid from the organic extract.

In this regard, there is a high likelihood that, in accordance with the projects according to the invention by extraction of the organic solvent to be used as the extracting agent, will have a significantly higher viscosity than water. In this case, according to the invention preferably received in the extraction column organic extracting agent was in the form of a dispersed phase, and acidic water as a continuous phase, [this facilitates, for example, the acceleration of mass transfer between both phases and can be used to achieve one and the CSOs same result more than short columns; besides, made of special steel extraction column and the corresponding built-in items are better wetted continuous aqueous phase, and the transport subject to extraction of substances from the continuous phase to the dispersed phase leads to the stabilization of the latter (its slight tendency to coalescence)]. In the case of using an organic extracting agent having a higher specific gravity as compared with acidic water, this means that extracting agent serves and is dispersed in the upper part of the column, and formed drops extracting agent lowered along the column. In the opposite case, i.e. when using an extracting agent with a lower specific weight in comparison with acidic water, extracting agent is dispersed in Cuba columns, and the resulting drops of extractant rise in the column. In the case of the extraction columns of the above types, are equipped with a built-in elements in the form of nozzles, nozzle bodies and/or plates, redispersion continuous phase should be well wetted with a similar built-in elements, because otherwise the droplets of the dispersed phase, as a rule, will be down on their surfaces.

In the simplest embodiment, the organic extracting agent is fed through a pipe, as a rule, the supply is by a round through-hole, located over the cross section of the column, and extending along each of the respective lengths of the cross-section of the extraction column, usually having the form of a circular cylinder, and pipes usually have the same cross-section (a set of these pipes are also called distribution manifold). In the case of applying the organic extracting agent in the upper part of the column of round through holes facing down, whereas when submitting extracting agent in the cube columns of round through holes facing up. The diameter (the largest transverse dimension) of the said through-hole is usually from 1 to 10 mm, preferably from 3 to 6 mm, in many cases, from 2 to 5 mm. in the simplest form, extracting agent can flow in pipe distribution manifold to flow out through the through-hole.

For the ongoing according to the invention the extraction of acidic water is in principle possible to use columns with stirring or centrifugal extractors. The use of columns with stirring helps to ensure good mutual contact phases. In appropriate technical and production version of agitators such columns are located on a common shaft. Pipe columns at the walls in the appropriate version equipped with stator rings. Is the th, as a rule, in the middle of the shaft in the typical case is equipped with working bodies, the design of which allows the mixer rotation between two adjacent stator rings. Such columns with stirring, for example, a column with rotating disks, the column of asymmetric rotating disks, column design Cuny or extractor type QVF with mixing bodies. For mixing and separation of moving in centrifugal extractors countercurrent phases of the desired centrifugal force. The latter also contributes to the qualitative separation of product purification/extract if both phases tend to form stable emulsions. Examples of devices of this type are the extractor Podbielnak or Westfalia separator.

The extraction device suitable for carrying out the invention method, preferably made of steel 1.4571. From similar steel also perform other devices designed to highlight the acrylic acid from the gas mixture of the reaction products heterogeneously catalyzed gas-phase partial oxidation.

The driving force for separation of the extract and product purification is the difference between the specific mass (g/cm3both liquid phases. The higher this difference, the more efficient is the sec the separation of phases and to a lesser extent emulsion is formed.

Thus, for carrying out the invention the extraction is preferably used an organic solvent, specific weight (kg/m3differs from the unit mass of water (kg/m3) ≥25 kg/m3preferably ≥50 kg/m3(when used for extraction pressure and temperature). Thus the difference between the values of the specific gravity, typically ≤250, respectively ≤150 kg/m3.

In addition, in a favorable embodiment proposed in the invention method, the dynamic viscosity of the organic extracting agent in the conditions of extraction ≤100 MPa·s, preferably ≤50 MPa·S. thus the dynamic viscosity, as a rule, is ≥1 MPa·S. According to the invention in a particularly favorable embodiment, the dynamic viscosity of the extracting agent is in the range from 2 to 10 MPa·S.

In addition, in accordance with the proposed invention the preferred method is the relatively high surface tension at the interface of two fluid phases.

Given the above, suitable for the extraction of acidic water extracting agents according to the invention are, in particular, organic liquid, the boiling point of which at normal pressure (1 atmosphere) exceeds 150°C, respectively 160°C. Examples of such the extractants are middle oil fractions from the distillation of paraffin, diphenyl ether, diphenyl or a mixture of these liquids, such as a mixture containing from 70 to 75% of the mass. diphenyl ether and from 25 to 30% of the mass. of diphenyl. Favorable is the use of a mixture containing from 70 to 75% of the mass. diphenyl ether and from 25 to 30% of the mass. of diphenyl, to which is added from 0.1 to 25 wt%. o-dimethylphthalate.

According to the invention particularly preferred organic solvents used for extraction of acidic water are esters of aliphatic or aromatic monocarboxylic or dicarboxylic acids (primarily with two esterified carboxyl groups, alcoholic component which contains 1-8 carbon atoms, while the acid component contains 5 to 20 carbon atoms. In the preferred embodiment, used for the esterification of an alcoholic component contains only two or one hydroxyl group. Particularly preferred alcohol components are monatomic (one hydroxyl group) or diatomic (two hydroxyl groups) alkanols. The number contained in the alcohol component of the carbon atoms (especially in the case of monatomic or diatomic alkanols) is preferably from 1 to 6, particularly preferably from 1 to 4 and even more preferably one or two. Aliphatic or aroma of the economic monocarboxylic or dicarboxylic acid mainly containing from 5 to 15 carbon atoms, preferably from 5 to 10 carbon atoms and particularly preferably 6 to 8 carbon atoms (these are primarily talking about the esterification of acids with alkanols with 1 to 4 carbon atoms, respectively, with one or two carbon atoms, including diesters). Preferred acid components corresponding esters are dicarboxylic acids (especially if tarifitsirovana both carboxyl groups)than monocarboxylic acid. According to the invention to an even more preferred acid components corresponding esters include phthalic acid, isophthalic acid, terephthalic acid and adipic acid. The latter primarily refers to a complex dialkylamino esters (alkyl with 1-8 carbon atoms, preferably 1-6 carbon atoms, more preferably 1-4 carbon atoms, better still with one or two carbon atoms). In accordance with these extracting agents, the most suitable for the implementation of the proposed in the invention method are dimethylphthalate, diethylphthalate (for example, Palatinol®A BASF Aktiengesellschaft), dimethyltotal, diacriticals, terephthalate, diethyltartrate, dimethyl ester of adipic acid and diethyl ester of adipic acid.

Other esters which are suitable for performing the proposed the invention the extraction of acidic water, are truefire phosphoric acid such as tributyl phosphate or tricresylphosphate. With appropriate kreselnye residues are derived ortho-kresila, meta-kresila or para-kresila. In addition, extracting agents suitable for execution proposed in the invention the extraction of acidic water are esters based on acrylic acid and a branched or non-branched monohydroxy alkanols with 6 to 12 carbon atoms (for example, 2-propylheptanol or 2-ethyl hexyl acrylate), as well as complex monetary and diesters based on maleic acid and a monohydroxy alkanols with 4-10 carbon atoms. According to the invention preferred of the above extracting agents are compounds having a boiling point of which at normal pressure exceeds 150°C, 160°C, 170°C, 180°C or 190°C.

Subject to extraction of acidic water in addition to acrylic acid and water, typically contains as another component acetic acid (in quantitative terms acetic acid, as a rule, represents the third component of the acidic water). Depending on the conditions of partial oxidation (type catalyst, the content of water vapor in the mixture of the reaction gases, the process temperature) acidic water may contain up to 10 wt. -%, accordingly, up to 5% of the mass. (often from 2 to 8% of the ACC.) or more of acetic acid. The mass ratio contained in the acidic water, acrylic acid and acetic acid often is about 2:1. The content of other acid side components that may be present in the acidic water is usually much lower. In accordance with this preferred according to the invention are extracting agents, mainly absorbing acrylic acid than acetic acid. Such extracting agents include, in particular, diethyl ester of phthalic acid.

According to the invention are also preferred extracting agents, which in the conditions of extraction does not interact with water and have only slight solubility in water. Especially high resistance to hydrolysis is characterized, for example, diethyl ether and phthalic acid. Another advantage of the diethyl ester of phthalic acid is a relatively high boiling point of this compound at normal (atmospheric) pressure, which is preferably used according to the invention the extracting agents (organic solvents) is ≥200°C, better ≥225°C and better still ≥250°C.

In addition, diethyl ether phthalic acid has a relatively low solubility in water, which leads to reduction of losses of the extras is Ghent. The temperature of the acidic water formed when implemented according to the invention of fractional condensation of the gas mixture of the reaction products typically ranges from 50 to 80°C., preferably from 60 to 70°C. this temperature usually has a second (preferred side) sampling liquid phase (the lower the temperature, the less the need for polymerization inhibitor, and in favorable embodiments, there is no need for separate addition of the polymerization inhibitor in acidic water, extracting agent, cleaning product and/or extract). In this regard, suitable in the production-technical variant extraction is also performed in the above temperature range. Thus, the acidic water is directed to the extraction device, which preferably is of the extraction column (particularly preferably a Packed column, preferably filled with nozzle Montz-Pak B1-350), according to the invention preferably has a temperature, which mainly corresponds to the above temperature range. Acidic water is preferably introduced into the bottom of extraction column, while in its upper part serves a relatively heavier extracting agent (preferably diethylphthalate). The temperature is sent to the extraction to the column of the extractant is usually not too much different from the temperature of the injected it acidic water. In a typical case, the difference between the respective temperatures ≥0 and ≤20°C, preferably ≥0 and ≤15°C, and in many cases ≥0 and ≤10°C. According to the invention a typical pressure selected from the condensation column acidic water at the point of selection is more than 1 to 1.5 bar, often 2 bar. Taken from the condensation column acidic water is fed into the extraction column by a pump. When the discharge pressure may be, for example, from 2 to 6 bar. According to the invention the working pressure in the extraction column set so that there was no need to use an additional pump for transporting the organic extract in the first Stripping column. Extraction of acidic water can in principle be carried out at higher or lower temperatures and at higher or lower pressures. At the start of the extraction column in a production-technically it is useful first to fill its acidic water, and then proceed to implemented, as described above, the supply of organic extracting agent, preferably in the upper part of the extraction columns in the form of drops. The flow of acidic water (preferably continuous phase) in the extraction column, in principle, can be directly through the respective nozzle columns. P is incipe acidic water can also be entered in the extraction column through the feed tube with one or more apertures in its walls (diameter of through holes in a typical case is from 5 to 10 mm).

As described above, in the production-technically it is advisable to use the extraction column, made of special steel. A typical thickness of its walls is from 5 to 20 mm is Similar to the extraction column usually provide exterior insulation.

In accordance with the proposed invention by way of the ratio V between directed to the extraction column flow organic extracting agent (E, kg/h) and the flow of acidic water (S, kg/h), i.e. the ratio (E:S, may be in the range from 0.05:1 to 20:1, preferably from 0.1:1 to 10:1, better from 0.8:1 to 1.2:1, and in a particularly preferred embodiment it is 1:1.

Depleted acrylic acid (extracted) acidic water is usually sent for recycling (for example, incineration or recycling at a water treatment facility). According to the invention in a typical case it is removed from the upper part of the extraction column as a cleaning product, while containing acrylic acid organic extract in a typical case is removed from the extraction column at the bottom.

Selection of acrylic acid from the organic extract, the temperature of the selection of which of the extraction columns mainly corresponds to the flow temperature of the acidic water in the extraction column, in principle, can be performed using different IU the odes of thermal separation, as well as a combination of such methods.

One of the suitable options for the allocation of acrylic acid is crystallized selection. You can use the method of crystallization, featured in the German patent applications DE A 19838845 and DE A 102005015637. The advantage of this method of crystallization of the selection is the possibility for more precise crystallization in comparison with other methods of thermal separation. That is, the structure of the formed crystals substantially does not depend (in the ideal case does not depend) on the composition of the liquid phase (liquid extract). The difference between fuzzy thermal separation from the above method is that the composition formed during the last phase containing a concentrated target product, differs sharply from the composition to be separation of the mixture. Thus, in the case of method a clear separation to obtain pure desired product, a single establishment of thermodynamic equilibrium, while in the case of using methods of fuzzy thermal separation for this purpose it is necessary to implement thermodynamic equilibrium several times in a row. According to the invention is particularly suitable crystallization methods for allocation of acrylic acid from the extract of the manifest is by suspension crystallization and layer-by-layer crystallization.

According to the invention the selection of acrylic acid from the extract even more preferably carried out by desorption, which primarily applies if the extracting agent is used as a compound, the boiling point of which at normal pressure of at least 60°C., preferably at least 80°C. and even more preferably at least 100°C. greater than the corresponding boiling point of acrylic acid, which is 141°C. For implementation desorption typically use a column effectively separates inline elements. As the latter is in principle possible to use any known effectively separating the embedded elements. Primarily these include plates, nozzles and/or bulk materials. The preferred mass transfer plates are bubble cap plates, sieve trays, such as force, respectively disastrous sieve trays (twin plate), valve plates and/or bowls of Torman (plates, respectively Torman®). The preferred bulk materials are rings, spirals, saddles, rings process, the ring of Into, ring Poll, seat Burleigh, saddle Intalox, materials, Top-Pak, and so forth, or braided materials. Even more preferred are double-flow plates and the and plates, Torman. Preferred plates of Torman are the corresponding single-threaded plates. In the case of a twin plates and plates of Torman first more preferably used in the lower part of the node desorption, while the latter in its upper part. A sufficient number used in the node desorption of theoretical plates, typically ranging from 5 to 10. The implementation of desorption in principle can be facilitated solely by the reduction of pressure. In technical respect, even more preferred is a lower partial pressure to be deformirovaniyu acrylic acid by dilution gas, which is not able to condense under the conditions of desorption (evaporation temperature odarivaemogo gas at atmospheric pressure, preferably at least 50°C below the boiling point of water) and generally inert with respect to chemical changes. Thus, even more preferred is the separation of acrylic acid from the extracted phase by steaming through the gas. That is the result of passing the gas through the extract of acrylic acid latter passes into the gas. The driving force behind such a process is a higher vapor pressure derived from the extract of acrylic acid compared to its partial pressure in the gas that obukowin is no transition of acrylic acid from the extract into a gas. The purpose of steaming extract preferably moves in a direction opposite to the direction of flow odarivaemogo gas (i.e. a counter). Therefore, the extract is preferably introduced into the upper part of the Stripping column, and otparyvali gas in its lower part. In an even more preferred embodiment, as odarivaemogo gas use is withdrawn from the upper part of the condensation column residual gas (respectively the residual gas mixture), a partial amount of this residual gas, the composition of which is similar to the composition of the overall residual gas or differs from it, or the gas composition corresponds to one or more inert components of the residual gas (for example, water vapor, nitrogen, carbon dioxide and/or air). According to the invention the advantage of the preferred use of the residual gas mixture as odarivaemogo gas due to the fact that in this case, on the one hand, there is no need to prepare additional odarivaemogo gas (which is also in the future would be subjected to additional utilization), and on the other hand, the fact that in this case, use otparyvali gas that does not contain components that differ from those that are characteristic of the overall process of selection of acrylic acid from the gas is Messi reaction products of partial oxidation. The residual gas, as a rule, consists of predominantly inert dilution gas used for the partial oxidation of the parent compounds with three carbon atoms to acrylic acid (such inert gases by partial oxidation remain largely chemically unchanged), and water vapor, usually formed by partial oxidation as a by-product and, if necessary, be added as a dilution gas, and oxides of carbon produced as a result of unwanted complete oxidation occurring in the form of side reactions (often partial amount of residual gas having a composition identical to the composition of the total residual gas mixture, also return as dilution gas phase partial oxidation; in the present description is a partial quantity is called the circulating gas partial oxidation, respectively, the gas circulation circuit). Residual gas sometimes contains small amounts of molecular oxygen, the remaining unspent at the stage of partial oxidation (its presence is preferred, allowing, for example, reduce the undesirable formation of polymer), neprivrednih parent compounds with three carbon atoms and/or neprevyshenie intermediate product. This inert R is sbavlyaya gases (for example, nitrogen, carbon dioxide, water and/or saturated hydrocarbons, and so forth), shared the stage partial oxidation, on the one hand, are useful because they are able to absorb the released stage partial oxidation reaction heat, and on the other hand, they usually at the same time ensure the safety of the implementation of the heterogeneously catalyzed gas-phase partial oxidation of the parent compounds with three carbon atoms, because their presence in the mixture of the reaction gases, the latter is outside the explosive range or in a securely controlled part of the explosive range (see, for example, German patent application DE A 19740253, DE A 19740252, DE A 10243625 and DE A 10332758, as well as international application WO 2004/035514).

In the case of use in desorption (Stripping) column as effectively separating the built-in elements of a twin plates diameter made in them through holes, usually ranging from 8 to 50 mm, preferably from 10 to 35 mm Diameter holes in the downward direction is preferably reduced. The distance between the plates (usually it is the same) often ranges from 300 to 800 mm, in many cases, from 400 to 600 mm and more often than 500 mm As described above, the node desorption is usually made of austenitic steel, predpochtitel what about the steel 1.4571 (DIN EN 10020).

To be Stripping the extract is injected into the upper part of the desorption column, preferably at its highest (theoretical) plate. In production is technically feasible is pre-heating the extract to a temperature in the typical case component from 80 to 120°C., often about 100°C. In a preferred embodiment, in the cube Stripping (desorption) of the column additionally served warm, which use internal and/or external indirect heat exchanger of conventional design (e.g., evaporator Robert, shell-and-tube heat exchanger with forced circulation, reducing shell-and-tube heat exchanger with circulation pump, heat exchanger and so on; see, for example, European patent application EP AND 854129) and/or a heating system with double walls (as a coolant, preferably use is obtained at a stage of partial oxidation steam). Cube Stripping column is preferably heated by an external circulation evaporator with natural or forced circulation. Especially preferably the external circulation evaporators with forced circulation (primarily the expansion evaporators). It is possible to use several in series or in parallel soedineniya (typical temperature of the cube is from 145 to 165°C., often it is about 155°C).

Otparyvali inert gas, unable to condense conditions desorption, is preferably introduced directly into the cube node desorption. Filing odarivaemogo inert gas from an external heat exchanger in which the specified gas down the necessary amount of heat from taken from the column bottom liquid, preferably carried out on one of the lower (theoretical) plates desorption columns, preferably between 2-nd and 4-th bottom of theoretical plates or below. Formed in Cuba desorption columns extracting agent mainly containing acrylic acid, preferably returned to the upper part of the column extraction with acidic water.

As the extracting agent, the return of the Stripping columns in the extraction column, usually has a higher temperature compared to the temperature generated in the extraction column extract, directed from the extraction column to the Stripping column extract and extracting agent returned from Cuba Stripping columns for the extraction, in appropriate variant having passed through the usual embodiment indirect (shell-and-tube or plate) heat exchanger, in which the heating of the extract and cooling of the extractant (in SV is due to the return of the extracting agent in the extraction column, if necessary, in Cuba Stripping columns should preferably perform the required active inhibition occurring in the extraction and Stripping the columns of polymerization, which in the case of presence in otpaivaem gas molecular oxygen, can be performed, for example, by p-methoxyphenol and/or fenotiazina). After extracting agent is usually subjected to additional cooling in an indirect heat exchanger, for example, by means of water as a refrigerant to a temperature of use of the extractant in the extraction unit sour water. From the Stripping column is usually derive from 0.01 to 1% of the mass. the bottom liquid (in terms of the flow of the extractant returned from Cuba Stripping columns for extraction), and after the above cooling flow return extracting agent usually complement a corresponding amount of fresh extracting agent. The output from the system cubic liquid can be subjected to disposal (for example, to burn together with residual gas) or rectification followed by the introduction of fresh extracting agent.

The temperature in the Stripping column odarivaemogo gas preferably at least largely corresponds to the temperature of the bottom liquid in the Stripping column, and the difference between the respective temperatures, as a rule, does not exceed 30°C, it is better not exceed 20°C. In the case of use as odarivaemogo gas residual gas specified temperature different is here you can provide, for example, the compression of a gas to a higher pressure. Such compression can preferably be undertaken in conjunction with gas circulation circuit to a pressure suitable for returning the residual gas phase partial oxidation of the parent compounds with three carbon atoms (for compression typically use centrifugal compressor). In a typical case, such a compression is carried out until a pressure of 2 bar to 4 bar, usually from 2.5 to 3.5 bar (typical pressure of compression in the case of using only the residual gas is more than 1 and ≤1.5 bar).

In a typical case, the flow rate odarivaemogo gas required for the release of acrylic acid Stripping of one kilogram of extract is from 1.5 to 2.5 nm3. Typical content of acrylic acid in otpaivaem gas (in the upper part of the Stripping column) is from 2 to 6% of the mass.

The heat in the cube Stripping columns with increasing flow rate used odarivaemogo gas can be reduced. The advantage of selection of acrylic acid from the extract by steam through a normally non-condensable under the conditions of desorption and inert odarivaemogo gas is, in particular, in that it is about the most effective technology, which simultaneously requires little energy and instruments who's costs. In addition, the advantage of this technology compared to, for example, crystallization or distillation selection of acrylic acid from the extract due to the lack of education additional liquid phase with a high concentration of acrylic acid, which would require additional costs for the inhibition of polymerization.

The above listed advantages, not least due to the fact that the containing otvarennuyu acrylic acid otparyvali gas, primarily in the case for steam used residual gas may be returned in the condensation column, which is used for the fractional condensation of the gas mixture of the reaction products of partial oxidation. In a suitable embodiment, the return otparyvali gas is introduced into the condensation column below the first side of the selection. Return otparyvali gas is preferably introduced directly into the VAT amount of the condensation column. In principle, it can be entered directly in cubic liquid.

Thus, one of the options proposed in the invention method is that the acrylic acid is contained at least in a partial number (at least 25 wt. -%, better at least 50 wt. -%, preferably at least 75% of the mass. or in General the number is as) a non-refundable in the condensation column acidic water, by extraction with an organic solvent is transferred to the solvent receiving containing acrylic acid organic extract, acrylic acid from which emit by steaming otparyvali gas, and containing otvarennuyu acrylic acid otparyvali gas return in the condensation column. Contained in otpaivaem gas otvarennuyu acrylic acid is in principle possible to return in the condensation column in the condensed state. Such condensed acrylic acid can be directed to further clean up after her Association with selected people from the condensation column crude acrylic acid.

In an even more preferred embodiment proposed in the invention method otparyvali gas containing otvarennuyu acrylic acid (respectively, at least a partial quantity otvarennoy acrylic acid), can be used to implemented in the second Stripping column steaming acrylic acid contained in taken from the condensation column bottom liquid before serving last for recycling (and only then to return otparyvali gas in the condensation column). According to the invention containing otvarennuyu acrylic acid otparyvali the gas from the second stage steaming preference is sustained fashion expose additional (counterflow) rectification, described in the international application WO 2004/035514 and German patent application DE A 10332758 (however, the direct use of residual gas as odarivaemogo gas), and then return in the condensation column.

Kubovy volume used for carrying out the invention method, the condensation column (respectively, in the most General case, the column is supplied efficiently separating inline elements) is the inner space of the condensation column below the lowermost effectively separating the embedded element (built-in items, such as plates, nozzles and nozzle bodies allow to increase the boundary surface between moving in a distillation column countercurrent phases).

As the volume builds up a so-called waste liquid primarily containing components having a boiling point of which at normal (atmospheric) pressure exceeds the boiling point of acrylic acid. These side products boiling temperature which exceeds the boiling point of acrylic acid, such as maleic anhydride, is added as polymerization inhibitors side components, such as phenothiazines, and side products formed in the process of fractional condens the tion of flow of the gaseous products of partial oxidation of the components of this thread. Such side products primarily include products unwanted free-radical polymerization of acrylic acid, which are formed despite the similar inhibition of polymerization. These include high-molecular compounds, which are formed by the condensation reaction of the various components of the gas mixture of the partial oxidation products. Such macromolecular compounds not least are the Michael adducts, which are formed due to the reversible attachment of Michael acrylic acid itself, as well as forming the dimer of acrylic acid (the so-called diacrylates acid), respectively, oligomers of acrylic acid (in the present description, the term "oligomers of acrylic acid" is always used to refer to the corresponding Michael adducts, but not oligomers resulting from the radical polymerization of acrylic acid). Due to the impact of elevated temperature while removing the formed acrylic acid [e.g., by "steaming" by preferably (chemically) inert and non-condensable under appropriate conditions gas] connection according to Michael may be reversible. Component of the bottom liquid of the condensation column is also itself prisutstvujuwuju small number of Monomeric acrylic acid, hence the usefulness of its allocation Stripping. Since the waste liquid condensation column also contains by-products, which at normal pressure boil at temperatures only slightly in excess of the boiling point of acrylic acid (for example, benzaldehyde, furfural and maleic anhydride), preferred is an additional countercurrent (i.e. backflow of phlegmy) rectification containing acrylic acid odarivaemogo gas this second stage steam (for example, before returning in the condensation column), which is suitable variant implemented in the same column, which leads to an increase purity containing acrylic acid of the second odarivaemogo gas.

Return contains otvarennuyu acrylic acid first odarivaemogo gas and/or the second odarivaemogo gas in the condensation column does not necessarily should be made directly.

On the contrary, there is also the possibility of at least partial or complete mixing containing otvarennuyu acrylic acid first odarivaemogo gas and/or the second odarivaemogo gas with a gas mixture of reaction products and then feed the resulting gas mixture in the condensation column.

The Union of the specified gas photocollage to make up, during and/or after, if necessary, implemented direct and/or indirect cooling of the gas mixture of the products of gas-phase partial oxidation.

To avoid confusion containing acrylic acid otparyvali gas (gas steam extract) in the following description referred to as "the first containing otvarennuyu acrylic acid by the gas, while otparyvali gas containing preferably rectified acrylic acid (gas sold in the condensation column CC steaming), called "second containing otvarennuyu acrylic acid by gas (respectively steaming extract called "the first Stripping", while kubovo steaming called "second Stripping", and so on). The pressure of the first gas steam extract of the output from the corresponding system of steam, typically ranges from 1.5 to 3.5 bar, frequently from 2 to 3 bar, for example 2.5 bar. The temperature of the first gas steam usually about 10°C below the temperature which has received the first Stripping column extract. The typical temperature of the first containing otvarennuyu acrylic acid gas is from 65 to 95°C, usually from 75 to 95°C, or 85°C.

To implement the second steam (including rectification odarivaemogo gas) is in principle possible to use any columns with eff the active separating inline elements, which may be, for example, nozzles, nozzle body and/or plates. In principle, it is possible to use columns with rotating nozzle elements (so-called rotary columns), providing splashes phlegmy with the formation of drops. According to the invention preferably use the second Stripping column, with only the plates and/or nozzles. While it is preferable to use a two-line plate, and in a particularly preferred embodiment, a Stripping column, as effectively separating the built-in elements contains only a two-line plates.

In accordance with the present invention under double-flow plates include plates, equipped with a single simple passing places (holes, slots and the like). Rising inside the second Stripping column gas and descending phlegm pass through each of such seats to the counter. The cross-section of seats to the famous image of a lead in accordance with the load on the second Stripping column. If too small cross section rising inside the Stripping column, the gas passes through the bushing place with such a high speed that it captures the downward phlegm mostly without effect separation. When there is too much cross-the cross of the AI seats to the ascending gas and descending phlegm pass by each other mainly without mass transfer, which leads to the risk of exploitation of the plates in a dry mode. Double-flow plates usually do not have drain pipes, connecting them with the neighboring plates. Each of the double-flow plates, obviously, can flush abutment against the inner wall of the second Stripping column. It can also be connected with the inner walls of the specified column by means of jumpers. When reducing the load on the second Stripping tower twin plates unlike hydraulically hermeticum plates with cross current operate in dry mode.

In an expedient embodiment of the invention, a Stripping column with a double-flow plates used to perform the second steam (including rectification)can include up to sixty twin plates. The ratio of D:U for such plates (D means permeable to the gas fraction of the total area of the plate, U means the total area of the plate), is mostly in the range from 10 to 20%, preferably from 10 to 15%.

Bushing seats twin plates preferably are round holes having the same for the same dish diameter. The latest in a suitable embodiment, ranges from 10 to 30 mm Diameter holes for the plates, located in the upper part of the column is preferably from 10 to 20 mm, respectively 10 is about 15 mm, while for plates, located in the lower part of the column, it is preferably from 20 to 30 mm round holes separate twin plates evenly preferably ordered in accordance with strict triangular gradation (see German patent application DE A 10230219). The burrs formed by cutting through holes in the double-flow plates of the second Stripping column, preferably facing down. Double-flow plates of the second Stripping column usually are at the same distance from each other. A typical distance between the twin plates is 300 to 500 mm According to the invention is also favorable distance between the plates, amounting to 400 mm In a suitable embodiment, the feed to be Stripping the bottom liquid (which before this can be used for direct cooling of the product gas mixture of the partial oxidation and/or to which may be added faction taglocity products selected in the lower part of the condensation column) carried out between the fourth and tenth double-flow plates of the second Stripping column (counting from the bottom). The temperature of the cube of the second Stripping column support in the predominant interval from 150 to 190°C., preferably from 160 to 180°C. the Operating pressure in the second Stripping column is usually from the is from 1 to 3 bar, most often from 1.5 to 2.5 bar.

The flow of energy in the second Stripping column is preferably carried out by means located outside of the column expansion shell and tube evaporator with forced circulation, in which the purpose of overheating send selected from the second Stripping column cubic liquid is then returned in the same column (see German patent application DE A 10332758). In principle, for this purpose you can use the vaporizer with pure forced circulation or evaporator with natural circulation, such as the evaporator Robert, which can also be mounted inside the second Stripping column.

The second Stripping column (as well as the condensation column, and the first Stripping tower) in production-technically it is reasonable to provide exterior insulation.

The phlegm can be obtained by direct and/or indirect cooling. According to the invention to obtain phlegmy preferably using the method of direct cooling. To this end, in the most simple variant passed through the last (theoretical) plate gas is directed into the quenching device which is integrated (planted by effectively separating part) to the second Stripping column, for example, over a plate of fireplace types irrespective of effectively separating the built-cell battery (included) is tov the second Stripping column. In principle, the quenching device may be located outside of the second Stripping column. As such, the hardening device, you can use any appropriate device known from the prior art (e.g., scrubbers, Venturi scrubbers, bubble columns or other devices with irrigated surfaces), preferably using scrubbers or irrigation coolers. Preferred are the corresponding flow device (e.g., a cone with a reflective plates). The purpose of the indirect cooling of the quenching liquid is usually passed through indirect heat exchanger. When this fit is any common heat exchangers. Preferred is the use of shell-and-tube heat exchangers, plate heat exchangers and air coolers. Suitable cooling medium is air (in the case of air cooler and cooling fluids, primarily water, such as surface water (in the case of cooling devices of another type). As the hardening liquid (in the following description also called "hardening liquid 0") production-technically it is advisable to use a partial amount generated during the hardening Conde is SATA. Another partial quantity generated during the hardening of the condensate mostly in the form of phlegmy return to the top (theoretical) plate of the second Stripping column (you can also select a small partial condensation, direct it to the stream taken from the condensation column bottom liquid and combine with this stream; a portion of the resulting mixture can be used as discussed below hardening liquid 1; the other part of this mixture forms a supply second Stripping column flow, and a relatively small residual quantity of this mixture, combine with the remaining partial amount of condensation, and the resulting mixture is used as part of phlegmy directed on the top (theoretical) plate of the second Stripping column, and part of the hardening liquid 0). In a typical case, the temperature of the quenching liquid 0 directly before it can be used for hardening is about 40°C, while the temperature is returned to the column phlegmy typically is about 80°C. the Mass ratio of the return phlegmy supplied to the cube of the second Stripping column of liquid (in some cases also trudnoca liquid) in the typical case ≥2. The ratio is often ranges from 2 to 10, preferably from 4 to 8.

The second is a Stripping column, like all other devices, which receive the liquid phase with a significant content of acrylic acid, obviously, should be operated with the simultaneous use of polymerization inhibitors. As the latter is in principle possible to use any known in the art and suitable for such a purpose, the polymerization inhibitors.

Examples of suitable polymerization inhibitors are phenothiazines and p-methoxyphenol. Often use a combination of these inhibitors. In a suitable embodiment, they are used in the form of a solution in pure acrylic acid. Para-methoxyphenol preferably added in the form of a melt.

In accordance with a particularly suitable option inhibition of polymerization in the quenching circuit 0 and the second Stripping column can be accomplished by filing in the quenching circuit 0 partial quantities derived from the condensation of the column bottom liquid containing the polymerization inhibitors, and optionally the fraction taglocity products. Inhibiting this way of quenching liquid 0 typically contains, for example, from 0.01 to 0.1% of the mass. p-methoxyphenol and from 0.01 to 0.5% of the mass. fenotiazina. Inhibition of polymerization contributes to molecular oxygen, usually present in the first containing acrylic sweet is the gas used as odarivaemogo gas in the second Stripping column.

A partial amount of fluid produced in Cuba for the second Stripping column, continuously remove and disposed of. Fluid-like state tieloserweg balance, if necessary, by adding an organic solvent, for example methanol. Instead of methanol is also possible to use other hydrophilic organic liquid, such as ethanol, liquid, featured in the international application WO 2004/035514, and mixtures thereof. The output from the cube of the second Stripping column flow in terms of the stream supplied to it from the condensation column bottom liquid is in the approximate range from 10 or 20% of the mass. up to 30% of the mass. Output stream in technical respect, it is expedient to divert the material flow opening in the overheated state of expansion evaporator with forced circulation, which supplies the second Stripping tower energy. The specified thread is subjected to deaeration and, for example, in diluted methanol condition sent, for example, incineration of industrial waste.

Taken from the quenching circuit 0 the second containing acrylic acid gas, cooled to a temperature in the typical case component from 70 to 90°C, can be returned in Conde is sational column (it should be stated, in a typical case, the second Stripping column as odarivaemogo gas use from 1 to 10 nm3the first contains otvarennuyu acrylic acid gas in terms of 1 kg supplied from the condensing column bottom liquid; the liquid in the cube of the second Stripping column is usually located in the fluidized state). The content of acrylic acid in the second containing otvarennuyu acrylic acid gas typically ranges from 15 to 20% of the mass. Contained in this gas of acrylic acid is in principle possible to return in the condensation column in the condensed state. The corresponding condensate of acrylic acid can also be combined with taken from the condensation column crude acrylic acid, and send to the further purification of acrylic acid. According to the invention acrylic acid back into the condensation column is preferably in the form of a second component containing otvarennuyu acrylic acid gas, that is in gaseous form (return of acrylic acid, in principle, can be realized also in partially condensed form).

Returned in condensing the second column contains otvarennuyu acrylic acid gas is preferably introduced below the first side selection (all of the above equally applies to return to condensational first containing otvarennuyu acrylic acid gas), although in principle it can also be entered in the direct path of the cooling gas mixture of products of gas-phase partial oxidation. With a production-technical point of view, the second containing otvarennuyu acrylic acid gas, it is advisable to return in the cubic part of the condensation column. Thus it can be entered directly in cubic liquid or in the space between the bottom mirror of the fluid and the first theoretical plate of the condensing column. The bottom of the condensation column is preferably equipped with a droplet separator (for example, centrifugal droplet separator)that prevents the drift bottom liquid rising gas. In addition, its bottom part can be separated from the lower effectively separating the built-in element of the first plate chimney type.

The residence time of the bottom liquid in the second Stripping column, supplied to it from the condensation column (if necessary including the selected fraction taglocity products), should normally be from 0.5 to 4 hours (for the final unloading tradecopier side component). In the cube of the second Stripping column, obviously, can be dosed catalysts for the cleavage of oligomers of acrylic acid, featured, for example, in international application WO 2004/035514.

In the cube the second Stripping Colo the us, obviously, you can add auxiliary tools, such as Komad®313 firms Mol (Hungary), and/or dispersant (known, for example, from European patent application EP AND 1062197 and/or patent applications U.S. US A 3271296), as well as, for example, such as tertiary amines (in particular, trimethylamine, triethylamine, N,N,N',N'-tetramethyl-1,6-hexanediamine and pentamethyldiethylenetriamine)reducing pollution supplying the necessary energy indirect heat exchangers and to increase the yield of acrylic acid. The amount of additives can be from 0.1 to 10 wt%. in terms of cubic liquid of the second Stripping column. Since such additives are preferably trudnosciami substances or they form with acrylic acid trudnoca substances, they are not susceptible to Stripping.

The advantages achieved through the use of the above options proposed in the invention method, due, in particular, the fact that their implementation can improve the yield of acrylic acid without significant reduction in purity of the output through the first side selection crude acrylic acid. This is not least also applies to the above variant of the steam, whereby for steam use residual gas condensation number is NY.

The degree of purity of both the first and the second containing otvarennuyu acrylic acid gas, which is determined by the content side components that interfere with the subsequent use of an acrylic acid, for example, to get super absorbent water polymers, is quite sufficient to acrylic acid contained in the corresponding total or partial amount of the first and/or second gases, could directly transfer from the gas phase of the first or second containing otvarennuyu acrylic acid gas in the aqueous solution of metal hydroxide (for example, a hydroxide of an alkali metal and/or alkali earth metal hydroxide, in particular NaOH, KOH, Ca(OH)2and/or Mg(OH)2), for example, in full accordance with the technology described in international application WO 2003/095410, and in the case of translation, for example, in an aqueous solution of caustic soda formed aqueous solution of sodium acrylate can be used, for example, to directly provide super absorbent water polymers by appropriate radical polymerization (see also international application WO 2003/014172).

This fact does not in the least due to the fact that by-products such as formaldehyde and formic acid, it is generally preferable remain in the aqueous phase acidic water. Pervyye second containing otvarennuyu acrylic acid gas, exempt from acrylic acid, for example, by counter-current washing of water with sodium hydroxide solution (or aqueous solution of the other of the above metal hydroxide) in the column that contains effectively separating the built-in items (plates, nozzle body and/or attachments), you can then return to the Stripping of the extract and/or send to burning.

In the typical case containing acrylic acid gas mixture of products heterogeneously catalyzed gas-phase partial oxidation of the parent compounds with three carbon atoms with molecular oxygen in the solid state of aggregation catalysts may have, for example, the following composition (especially if as the parent compound with three carbon atoms using propylene):

from 1 to 30% of the mass.acrylic acid
from 0.05 to 10 wt. -%molecular oxygen
from 1 to 30% of the mass.water
more than 0 to 5 wt. -%acetic acid
more than 0 to 3% of the mass.propionic acid
Bo is its 0 to 1% of the mass. maleic acid and/or maleic anhydride
from 0 to 2% of the mass.acrolein
from 0 to 1% of the mass.formaldehyde
more than 0 to 1% of the mass.furfural
more than 0 to 0.5% of the mass.benzaldehyde
from 0 to 1% of the mass.propylene
the rest (up to 100 wt. -%)basically inert gases, such as nitrogen, carbon monoxide, carbon dioxide, methane and/or propane.

The gas mixture of the reaction product usually contains ≥0,005 mol.%, often ≥0,03 mol.% furfural (in terms of the number contained in acrylic acid). At the same time, the relative content of furfural, typically ≤3 mol.%.

Gas-phase partial oxidation can be carried out in a known from the prior art methods. So, for example, gas-phase partial oxidation of propylene can be carried out in two consecutive stages implemented oxidation, as described in European patent applications EP AND 700714 and EP A. Gas-phase partial oxidation, obviously, can be done as proposed in the emetsky the patent applications DE A 19740253 and DE A 19740252.

It is preferable implementation of the partial gas-phase oxidation of propylene, as described in the German patent application DE A 10148566, as in this case produces fewer side components. As a source of propylene can be used propylene polymer purity or chemically pure propylene according to the German patent application DE A 10232748. When using propane as the starting compound with three carbon atoms partial oxidation can be performed, as described in the German patent application DE A 10245585.

Gas-phase partial oxidation, in principle, can be made as described in patent application US US 2006/0161019, international applications WO 2006/092410, WO 2006/002703, WO 2006/002713 and WO 2005/113127, German patent application DE A 102004021763, European patent application EP AND 1611076, international application WO 2005/108342, European patent applications EP AND 1656335, EP AND 1656335, EP AND 1682478 and EP AND 1682477, German patent applications Nr.10 2006054214.2 and Nr.10 2006024901.1, European patent applications EP AND 1611080 and EP AND 1734030, German patent applications Nr.10 2006000996.7, 10 2005062026.4 and 10 2005062010.8, and in international patent Nr. PCT/EP 2006/065416, PCT/EP 2006/067784 and PCT/EP 2006/067080.

The temperature of the gas mixture of the reaction products of gas-phase partial oxidation is often ranges from 150 to 350°C., in many cases, from 200 to 300°C, sometimes is about 500°C.

In technical expedient embodiment, the hot gas mixture of the reaction products by direct cooling is cooled in the quenching device 1, generally to a temperature of from 100 to 180°C, after which in accordance with the preferred in the production-technical variant used in conjunction with the hardening liquid 1 for fractional condensation is directed preferably to the lower section of the condensation column containing effectively separating the built-in elements (preferably at the bottom, for example, cubic part of this column).

The condensation column, in principle, can be equipped with any known inline elements, first of all plates, nozzles and/or nozzle bodies. While the preferred plates are cap, mesh, valve and/or a two-line plate. The total number of plates in plate condensation column typically ranges from 20 to 100, often from 20 to 80, preferably from 50 to 80.

According to the invention, it is preferable featured in the German patent applications DE A 10243625, DE A 19924532 and DE A 10243625 condensation column, which as effectively separating the built-in elements (bottom-up) first double-flow plates, and then hydraulically sealing plate PE cristim current (for example, plates Thormann®). While the number of double-flow plates may be from 5 to 60, often from 25 to 45, while the number of hydraulically sealed plates with cross current is from 5 to 60, often from 30 to 50. In the case of preferred according to the invention the formation of acidic water (the content of acrylic acid in the phlegm, as a rule, is ≤15% wt., accordingly, in some cases, ≤10% of the mass.) as effectively separating inline elements are preferably used valve plates (see German patent application DE A 19924532 and DE A 10243625). In principle, it is possible to use also other well-known effectively separating the built-in elements (in the most General case, a separate condensation zone of the column rather than the location above each other in the same column, obviously, can be completely performed in the same way as the corresponding series-connected with one another of smaller size, and therefore the term "condensation column"used in this description in some cases, and the term "column"as used in the General case, also serve to denote these sequences corresponding columns of a smaller size).

As the hardening device 1 can be used intended for any such purpose and of the local in the prior art device (e.g., scrubbers, Venturi scrubbers, bubble columns or other devices with irrigated surfaces), preferably using scrubbers or irrigation coolers.

The purpose of the indirect cooling or heating of the quenching liquid 1 is preferably, but not necessarily, passed through a heat exchanger, which primarily refers to the stage start. Suitable are any common heat exchangers. Preferred are shell-and-tube heat exchangers, plate heat exchangers and air coolers. Suitable cooling medium include air (when used with the appropriate air cooler and cooling fluids, primarily water (in the case of cooling devices of another type).

As the hardening liquid 1 can be used, for example, selected from the cube condensation columns cubic liquid (optionally combined with the output of the quenching circuit 0 condensate), the fraction taglocity products produced from situated near the cube side selection, or a mixture of the specified bottom liquid and the specified faction taglocity products that primarily applies if its bottom part and the bottom (theoretical) plate (at the bottom of effectively separating the built-in ale the NT) are separated from each other by a plate chimney type. Through the above heat exchangers, if necessary, pass only a portion selected from a cube condensation column hardening liquid 1. The suitable temperature hardening liquid 1 at the entrance to the hardening device 1 typically ranges from 90 to 120°C.

The place of entry into the condensation column subjected to hardening (or chilled other method, and non-refrigerated) product gas mixture of the catalytic gas-phase partial oxidation according to the invention preferably in a mixture used for direct cooling of quench liquid 1) preferably is located in its VAT volume, preferably equipped with built-in centrifugal droplet separator and, as a rule, separated from the lower effectively separating the built-in element of the first plate fireplace type (in this case with a production-technical point of view it is advisable to continuously direct the fraction taglocity products through the corresponding connecting pipe or overflow pipe to the cube of the condensation column). In accordance with the preferred option (which is discussed below as the only applicable without restrictions option) under the specified plate I mean the first plate of the first series located appropriate at equal distances, etc is g other twin plates. Plate chimney type at the same time performs the function of the cumulative plates, which provide continuous sampling of the condensate fraction taglocity products), then sent as part of the quench liquid 1 in the quenching device 1 or cubic the First series of twin plates completes the second plate fireplace type (detecting plate). With this second catching plate through the first side selection srednetepa faction continuously selected crude acrylic acid, the degree of purity which preferably ≥90% wt., accordingly ≥95% of the mass.

In accordance with feasible option specified crude acrylic acid is directed to the additional distillation (distillation and/or crystallization treatment, and at least part of the bottom liquid and/or uterine liquor resulting from the respective distillation (rectification) and/or crystallization, return in the condensation column, introducing them to a place below the first side of the selection, but above the first catching plates. Specified recirculation is preferably carried out with simultaneous heat recovery. Namely, the repayment cold uterine liquor is passed through one or more series-connected indirect heat exchangers (e.g. the R, spiral heat exchanger) for cooling selected from the condensation column and sent to the heat exchanger with its opposite side subject to additional crystallization purification of crude acrylic acid. Thereby simultaneously provide heating of the mother lye. For this purpose it is preferable to use two series-connected plate heat exchanger.

In an expedient variant selected as srednetepa fractions of crude acrylic acid with the purpose of further purification sent for crystallization. Appropriate methods of crystallization in principle not subject to any restrictions. The crystallization can be performed in continuous or periodic, single-stage or multi-stage mode to any degree of purity.

If necessary, before the crystallization to be crystallization purification of crude acrylic acid is preferably water can be added (in this case, the acrylic acid typically contains up to 20% of the mass. or up to 10 wt. -%, in most cases, up to 5% of the mass. water, calculated on the amount of acrylic acid). With increased content of aldehydes or other adverse components in the acrylic acid from the addition of water should be avoided, because the aldehydes can take over the function of water. According to the image the structure even more preferred is the addition of water in the form of acidic water. In such case, increasing the yield of pure acrylic acid.

Unexpectedly, it was found that even when the prior is added to the crude acrylic acid sour water (a similar event at the same time provides an increase in the yield of acrylic acid) stringent requirements regarding the purity of acrylic acid, sufficient for the purpose of esterification, for example, to obtain n-butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate or ethyl acrylate (purity acrylic acid should be 98% of the mass.), can be satisfied through the implementation of a single crystallization. In an expedient variant, a similar operation is performed in the form of a suspension crystallization, similar to those described in column 10 of the German patent application DE A 19924532, respectively, in example 1 of German patent application DE A 10223058 (for example, in the mould with cooling disks described in the international application WO 2006/111565). The resulting suspension crystallization crystals of acrylic acid have the form of cubes to rectangular parallelepipeds. Ratio (L:D) length (L) of the respective crystals to the thickness (D) is usually in the range from 1:1 to 6:1, preferably from 1:1 to 4:1, particularly preferably from 1.5:1 to 3.5:1. The thickness (D) crystals of the usual ranges from 20 to 600 μm, often from 50 to 300 μm. The length (L) of crystals usually corresponds to the interval from 50 to 1500 μm, often from 200 to 800 μm. The Department suspended kristalliset from the residual mother lye (in the case of receiving suitable for the esterification of acrylic acid) can be performed in a centrifuge (e.g., two-stage or three-stage pulse centrifuge), and in the preferred embodiment, selected on the centrifuge crystals washed with molten pure crystallization. In the case of separation of suspended kristalliset from the residual mother lye washing column, for example column for washing the melt, which is implemented, for example, in accordance with the international application WO 01/77056, German patent applications DE A 10156016 and DE A 10223058, international applications WO 2006/111565, WO 04/35514, WO 03/41833, WO 02/09839 and WO 03/41832, German patent application DE A 10036881 or international applications WO 02/55469 and WO 03/78378 by a single crystallization can be distinguished acrylic acid, suitable even for getting superabsorbents (the degree of its purity is ≥99.7% of the mass.accordingly ≥99.9% of the mass), that is, acrylic acid, suitable for production of super absorbent water or other polyacrylates. In accordance with feasible option in such case, any amount allocated to the mother lye return in condensation column.

Crystallization can also be performed as recommended in the European patent application EP AND 616998 fractional crystallization with a falling film. A similar process may include, for example, two, three or more (for example, from two to four) cleanup operations (suitable molds with a falling film may contain, for example, from 1000 to 1400 crystallization of pipes ranging in length from 10 to 15 m and an external diameter of from 50 to 100 mm). Uterine liquor allocated to higher stages of treatment, you can return to one of the previous stages of cleaning. Uterine liquor allocated for the first stage of purification, preferably fully return in the condensation column. In another embodiment, to return to one of the previous stages of purification of the mother liquors of the individual purification steps can be returned in the condensation column in their entirety. Pure product penultimate stage of purification can be directed to the last step of purification is fully or partially. In the case of a partial filing the remaining number of specified pure product, usually mixed with a pure product of the last stage of purification, getting a usable end product.

In a suitable embodiment of the present invention, a partial quantity of the crude acrylic acid is taken in place of cond is national columns, located above the first side of the selection, served on a two-line plate below the corresponding catching plates. On specified plate if necessary, as a rule, serves also be returning in the condensation column uterine liquor. Before serving uterine liquor, usually heated in accordance with the above method heat recovery up to temperature, which practically corresponds to the temperature selection crude acrylic acid.

Another partial quantity of the crude acrylic acid, selected in place of the condensation column located above the first side of the selection, heat for 10-15°C, preferably by indirect heat exchange and transfer in the condensation column above selection, preferably directly below followed by the first double-flow plates. Such a technical event has a positive impact on the content of acetic acid in selected crude acrylic acid.

Above the second capture plates ordered the second series of twin plates in suitable option located at the same distance from each other, followed by hydraulically sealing mass transfer plates with transverse current (for example, plates of Tormina or modified plates of Torman according to the German application for Pat is NT DE A 10243625), which in a suitable embodiment are also the same distance from each other. The top two plate if necessary made in the form of the distribution plate. That is, it is equipped with, for example, a drain trench with the winding overflow.

The first bottom plate of Torman has reasonable production-technical point of view, by design, according to which the liquid flows with her six drain pipes in the form of corresponding pipes. These pipes are hydraulically sealed relative to the gas volume located below the double-flow plates. In technical respect is advisable to decrease the height of backwater six drain pipe in the direction of the flow plates with cross-current. Hydraulic seal holes for idle discharge is preferably provided with a reflective plate. Drain pipes preferably evenly distributed in the second half, particularly preferably in the last third of the cross-section of the plate (opposite the entrance to the dish).

Hydraulic seal is realized in the gate with sloped overflow device (angle 45°).

A series of mass transfer plates with transverse current completes the third plate fireplace type (detecting plate).

N is d third catching plate are preferably double-flow valve trays. The principle of operation of the valve plates, and used according to the invention the valve plates are described, for example, Technische Fortschrittsberichte, volume 61, Grundlagen der Dimensionierung von Kolonnenboden, S. 96-138. The main feature of such valve plates is that they allow couples through the corresponding hole with a flow rate that can be varied in a wide range. According to the invention preferably use a ballast plate. It is about the plates, the holes which are cells with closed cargo holes. According to the invention particularly preferred are the valves W12 firm Stahl (Germany, Bernheim). In the volume of the valve plates is preferential condensation of water and less volatile than water components. The resultant condensate is acidic water.

With a third of the arresting plate through the second side selection continuously excrete acidic water. Part of selected acidic water return in the condensation column on the top mass plate with transverse current. Another part of selected acidic water by indirect heat exchange is cooled and after running in a suitable embodiment, the crusher drops also return in the condensation column. One of the cooled partial amount of acidic water (with tempera is uroy from 15 to 25°C, preferably from 20 to 25°C) return to the upper valve plate of the condensation column, while the other is cooled partial quantity (with temperatures ranging from 20°to 35 ° C, preferably from 25 to 30°C) return on the valve plate, located approximately midway between the third detecting plate and the upper valve plate. The acrylic acid contained in the selected remaining number of acidic water can be distinguished proposed in the invention method.

Partial cooling acidic water, which can be accomplished through one or more series-connected indirect heat exchangers, provide due to the fact that the corresponding partial amount of acidic water is passed through the device for the evaporation of the starting compound with three carbon atoms (for example, through the evaporator propylene), which specified the original connection with the aim of implementing the heterogeneously catalyzed gas-phase oxidation is transferred to the gas phase.

More volatile than water, the components are removed from the upper part of the condensation column in the form of residual gas (respectively the residual gas mixture) and usually at least partially return to the stage of gas-phase partial oxidation as dilution gas (gas circulation circuit) ° C to avoid condensation of the residual gas mixture in the compressor flow circuit it is subjected to a preliminary heat in the indirect heat exchanger. Not be returning to the circuit part of the residual gas mixture is usually sent for incineration. As indicated above, a portion (preferably compressed) residual gas mixture in the preferred embodiment of the invention used as odarivaemogo gas for separation of acrylic acid from the extract and from the bottom liquid of the condensation column. Gas-phase partial oxidation is preferably carried out using an excess of molecular oxygen, and in the case of using a residual gas mixture as such odarivaemogo gas residual gas mixture, and therefore, the first and second otmerivayuschie gases containing molecular oxygen.

In order to inhibit polymerization in the upper hydraulically compacted mass transfer plate with transverse current submit a solution of p-methoxyphenol in acrylic acid or (according to the invention preferably) melt p-methoxyphenol, and if necessary (in both cases) advanced solution fenotiazina in acrylic acid. The solvent preferably used pure acrylic acid obtained by further purification selected from the condensation column crude acrylic acid. For example, you can use the resulting additional the additional crystallization purification of pure acrylic acid (pure target product). An appropriate solution should also be used to stabilize the pure target product.

Approximately in the middle section of the column with hydraulically compacted mass transfer plates with transverse current is further added a solution fenotiazina in the pure target product.

The formation of acidic water is in principle possible to implement, for example, after the first condensation column (see German patent application DE A 10235847). In this case, from the gas stream boiling compounds escaping from the top of the first condensing column, in a suitable embodiment, by direct cooling in the volume that does not contain inline elements (such amount to form acidic water can also be mounted inside of the condensation column; in this case, the quenching volume without built-in items are usually separated from the top effectively separating the embedded element within the condensation column, for example, by plates fireplace type), or serial attached volume with built-in features (second column) by hardening liquid 2 condense water. The resulting condensate is acidic water. Part of the acidic water in a suitable embodiment, return to the top of the first condensing the column to increase its separating ability. Another part of the acidic water is subjected to indirect cooled in an external heat exchanger and is used as a hardening liquid 2, and acrylic acid can also be extracted from the residual amount of the acidic water proposed in the invention method. Flow components boiling compounds, volatility than the volatility of water, also form a residual gas, which is typically at least partially return to the stage of gas-phase partial oxidation as a gas circulation circuit, respectively, are used as odarivaemogo gas.

In accordance with a preferred embodiment of the proposed invention in the way of a twin plates in the appropriate case, are located along the condensation column to approximately, which corresponds to a cross section of the column, from which (towards the upper part of the column), the content of acrylic acid in the phlegm is ≤90% of the mass.

As described above, in accordance with this preferred option fractional condensation of the number of double-flow plates, usually ranging from 25 to 45. Above the ratio of D:U in a suitable embodiment, the structural design of a twin plates ranges from 12 to 25%. When this bushing seats dogpatch the x plates are preferably round holes standard diameter. Suitable diameter of the holes ranges from 10 to 20 mm. Diameter holes along the condensation column in the downward direction if necessary, may decrease or increase and/or number of holes may decrease or increase (for example, all the holes can have a standard diameter pillars 14 mm, however, the ratio of D:U in the downward direction can be increased from 17.4% to 18.3%). However, there is also a variant of embodiment of a twin plates, in accordance with which all of them have the same number of holes. Furthermore, all the openings for each of the individual two-line plates evenly preferably ordered in accordance with strictly triangular gradation (see German patent application DE A 10230219).

In addition, burrs remaining after cutting through holes in the double-flow plates of the condensation column, preferably facing down, which reduces the undesirable formation of polymer.

According to the invention it is expedient if the number used in the condensation column double-flow plates corresponds to about 10 to 15 theoretical stages.

As indicated above, the number of hydraulically compacted mass transfer plates with transverse current, located after the series duhp the exact plates, in a preferred according to the invention the condensation column, usually ranging from 30 to 50. Such mass transfer plates characterized by the ratio of D:U, which is suitable variant is from 5 to 25%, preferably from 10 to 20% (as indicated above, under the relation D:U in the General case, the mean expressed as a percentage the ratio of flow cross-section of the plates to the total cross section; preferably shared mass transfer plates with transverse current appropriate ratio D:U in the General case is in the above range).

According to the invention preferably use a single-threaded mass transfer plates with transverse current.

The number of hydraulically sealed plates with cross-current in the preferred embodiment, the fractional condensation of the product gas mixture, as a rule, expect so that it matches the number of theoretical stages, approximately from 10 to 30, most often 25.

As hydraulically sealed plates with cross-current, and optionally shared the valve plates have at least one drain pipe. Plates of both types can have both single-threaded and multi-threaded, for example a two-line, constructi the s ' performance. When this plate with a single-threaded execution can have more than one drain pipe. The supply pipe valve plates, as a rule, also equipped with a hydraulic seal.

Inhibition of polymerization hardening system 1 for the product gas mixture of the partial gas-phase oxidation can be carried out both by means of polymerization inhibitors contained in used for hardening the bottom liquid from the condensation column)and by inhibitors of polymerization contained in used for hardening faction taglocity products (from the condensation column).

The advantage of the invention method is that it allows for an increased output of crude acrylic acid, mostly with the same degree of purity. Any embodiments of the present invention is primarily related to the gas mixture of the reaction products obtained (preferably two-stage heterogeneous partial oxidation of propylene to acrylic acid. The above preferred option proposed in the invention method is in no way limits its General feasibility.

In conclusion, it should again be noted that both the first and second otmerivayuschie gas which preferably contain molecular oxygen.

In addition, it should be noted that in accordance with the proposed invention is a method in the condensation column via submission place, located between the first side selection and the second side selection, if necessary impose different from phlegmy liquid absorbent, the boiling temperature TSwhen atmospheric pressure is higher than or equal to the boiling temperature TWwater at atmospheric pressure. In principle it is possible to use the technology described, for example, in European patent application EP AND 1818324. Suitable absorbents are, in particular, high-boiling organic liquid. Examples of suitable absorbents are organic liquids, featured in the German patent application DE A 10336386 and cited in the prior art for use as absorbents. Moreover, you can also use absorbents, featured in European patent application EP AND 1818324.

For example, suitable absorbents are high-boiling (inert) liquid hydrophobic organic liquid, described in European patent application EP AND 722926, as well as in the German patent applications DE A 4436243 and DE A 10336386 (in particular, dimethylphthalate, diethylphthalate and/or diphenyl). It is, for example, the liquids, the boiling point of which at normal (the atmosphere is nom) pressure exceeds the boiling point of acrylic acid, moreover, at least 70% of the mass. molecules of which consist of such liquid, does not contain possessing external action of the polar groups, and therefore, for example, are not able to form hydrogen bonds. Examples of such absorbents may serve a mixture of diphenyl ether (70 to 75% of the mass.) with diphenyl (from 25 to 30 wt. -%), called Diphyl®and a mixture containing from 70 to 75% of the mass. diphenyl ether and from 25 to 30% of the mass. of diphenyl and from 0.1 to 25 wt%. dimethylphthalate (in terms of a mixture of diphenyl ether with diphenyl).

As such absorbents, obviously, can be used as aqueous liquids. Examples of suitable aqueous liquids are compounds featured in European patent application EP AND 1818324. Such absorbents, in particular, water. As such water absorbent, obviously, you can also use the extracted aqueous phase remaining after implemented according to the invention the extraction of acidic water.

The purpose of adding the above absorbents is the targeted reduction in the number of certain side components typically contained in the crude acrylic acid withdrawn from the condensation column via the first side selection. Therefore, in the favorable case itself is used, the binder does not contain such side compo is having in any case, their content must be extremely small, and preferred is a complete absence of such components.

In the case of the use of water absorbent favorably, for example, to the mass number contained in the individual side components was less than in the corresponding acidic water.

The supply of water absorbent (e.g., water) is particularly advantageous to carry out, in particular, to reduce the content of aldehydes possessing comparable with acrylic acid boiling point (especially furfural), in the crude acrylic acid withdrawn from the condensation column via the first side selection. As such absorbent is in principle possible to use a mixture of water and organic liquids. This mixture can also be multi-phase.

In a preferred embodiment of the invention, the absorbent material can be fed into the condensation column in place, are at the same level with the place of supply phlegmy. In the condensation column, you can apply the mixture of these two threads.

The temperature in the condensation column of absorbent material can be varied within wide limits. It can be both above and below the temperature of phlegmy. The temperature of the absorbent often differs from the temperature FLEG is s by an amount component of ±20°C. Phlegm and absorbent preferably have the same temperature.

If selected through the first side selection crude acrylic acid contains shared absorbent, it is separated from the crude acrylic acid, as a rule, by the above-described additional crystallization purification. Otherwise, the shared absorbent is usually in the output of the condensation column bottom liquid, and after separation can be reused as an absorbent in accordance with the above-described technology.

In an expedient embodiment of the invention the mass flow fed into the condensation column of the adsorbent in terms of acrylic acid (component mass flow fed into the condensation column gas mixture of the reaction products) is from 0 to 30%.

In technical respect, it is advisable to supply absorbent in the upper third of the condensation column between the first side selection and the second side of the selection.

Realized according to the present invention crystallization treatment (primarily additional crystallization purification in the following paragraphs 16-20) instead of using the processing according to the present invention the crude acrylic acid can be used for processing crude acrylic acid, obtained in accordance with German patent application DE A 10336386. Specified additional crystallization purification, obviously, can also be used for any mixture of these two types of crude acrylic acid. Such crystallization purification use, for example, in the case of a parallel implementation of the present invention in technology selection and technology selection according to DE A 10336386: the aim of crystallization purification is the separation of acrylic acid from product gas mixture (optionally carried out in parallel) heterogeneously catalyzed partial gas-phase oxidation of the parent compounds with three carbon atoms. In situations when it is necessary to temporarily stop proposed in the invention of fractional condensation to selection of acrylic acid, however, the flow obtained according to DE A 10336386 crude acrylic acid on the crystallization purification continues, partial mass flow (mass flow in terms of the flow directed to additional crystallization purification of crude acrylic acid) would range from 5 to 30%, typically from 10 to 20% (selected crystallised must continue to meet the requirements of the specifications); thread residual amount of the mother lye generally return of Christ is lisalu (in a mixture with a mass flow of raw acrylic acid), uterine liquor formed in the allocation of kristalliset of suspension kristalliset acrylic acid, temporarily stored in the storage tank (supply in the storage tank can be done continuously or cyclically) and after rebooting fractional condensation gradually return to fractional condensation in a mixture formed according to the invention the mother liquor (corresponding to a mass flow rate of more than 0 to 20%, more preferably 0 to 10% in terms of return on a fractional condensation mass flux generated according to the invention the mother lye). When sampling from a storage tank can be done continuously or cyclically. Usually this selection is performed so that the resulting crystallized met the requirements of the specifications (design output node of crystallization, as a rule, exceeds the design capacity of the receiving node crude acrylic acid; additional crystallization purification of short-term can be made with performance exceeding the design capacity of the site crystallization).

Thus, the present invention is carried out primarily in accordance with the following options.

1. The method of obtaining acrylic acid, according to which way is carried out at elevated temperature heterogeneously catalyzed gas-phase partial oxidation with molecular oxygen of at least one of the corresponding starting compound with three carbon atoms in the solid state of aggregation catalysts receive a gas mixture of products containing acrylic acid, water vapor and side components, the temperature of this mixture, if necessary, reduced by direct and/or indirect cooling, after which this mixture is sent to feature effectively separating the elements of the condensation column, along which she rises while passing fractional condensation, and through the first side selection above the place of supply of the gas mixture of the reaction products of the condensation column, the condensation column deduce depleted water and side components of the crude acrylic acid as the target product, through above the first side selection of the second (preferred side) sampling of the liquid phase from the condensation column display containing acrylic acid and side components of the acidic water from the top of the condensation column output residual gas mixture containing side components boiling at lower temperatures than water, from a cube condensation column deduce cubic liquid containing acrylic acid and by-products and side components boiling at a higher temperature than acrylic acid, partial to the number of selected acidic water as such and/or after cooling return in the condensation column as phlegmy and crude acrylic acid if necessary, subjected to additional cleaning at least one other method of thermal separation, characterized in that the acrylic acid contained in at least a partial amount of non-refundable in the condensation column acidic water, transferred to an organic solvent by running this solvent extraction, followed by formation containing acrylic acid organic extract, from which the acrylic acid in the future, allocate at least one method of thermal separation, with selected acrylic acid back into the condensation column and sent for further purification of crude acrylic acid and/or transferred to an aqueous solution of the hydroxide of the metal.

2. The method according to claim 1, characterized in that the starting compound with three carbon atoms is propylene, acrolein or a mixture of propylene with acrolein.

3. The method according to claim 1 or 2, characterized in that the acrylic acid contained in at least 25% of the mass. non-refundable in the condensation column acidic water, transferred to an organic solvent by running this solvent extraction, followed by formation containing acrylic acid organic extract, from which the acrylic acid in the future, allocate at least one method of thermal separation, with selected acrylic acid returns the Ute in the condensation column, sent for further purification of crude acrylic acid and/or transferred to an aqueous solution of the hydroxide of the metal.

4. The method according to one of items 1 to 3, characterized in that the extraction of acrylic acid from the acidic water is carried out in an extraction column, which as effectively separating the built-in elements contains nozzles and/or sieve trays.

5. The method according to claim 4, characterized in that the upper part of the extraction column serves organic solvent, and in the area of its cube acidic water, and the organic solvent falls in the form of a phase dispersed in a continuous acidic aqueous phase, or characterized in that the upper part of the extraction column serves acidic water, and in the area of its cube organic solvent, and the organic solvent rises in the form of a phase dispersed in a continuous acidic aqueous phase.

6. The method according to one of claims 1 to 5, characterized in that the organic solvent contains at least one ester-based aliphatic or aromatic monocarboxylic acid having 5 to 20 carbon atoms and alcohols with 1 to 8 carbon atoms.

7. The method according to one of claims 1 to 5, characterized in that the organic solvent contains at least one complex fluids based on aliphatic or aromatic monocarboxylic acid having 5 to 20 carbon atoms and SP the mouth with 1 to 8 carbon atoms.

8. The method according to one of claims 1 to 5, or claim 7, characterized in that the organic solvent is dimethylphthalate, diethylphthalate, dimethyltotal, diacriticals, terephthalate and/or diethyltartrate.

9. The method according to one of claims 1 to 8, characterized in that the boiling point organic solvent at atmospheric pressure is ≥200°C.

10. The method according to one of claims 1 to 9, characterized in that the acrylic acid is recovered from the organic extract by first steaming otparyvali gas, and the first otparyvali gas containing otvarennuyu acrylic acid, return in the condensation column and/or otvarennuyu acrylic acid contained in the first otpaivaem gas is transferred into an aqueous solution of a metal hydroxide.

11. The method according to one of claims 1 to 9, characterized in that the organic extract by steam first otparyvali gas to produce acrylic acid, and formed the first otparyvali gas containing otvarennuyu acrylic acid, is used as the second odarivaemogo gas for the purpose of steaming acrylic acid contained in the output of the condensation column bottom liquid, and the resultant second otparyvali gas containing otvarennuyu acrylic acid, return in the condensation column and/or otvarennuyu acrylic is th acid, contained in the second otpaivaem gas is transferred into an aqueous solution of a metal hydroxide.

12. The method according to claim 11, characterized in that the steam derived from the condensation of the column bottom liquid is carried out in a fitted effectively separating the built-in elements of the Stripping column, the temperature in the cube which is from 150 to 190°C.

13. The method according to claim 11 or 12, characterized in that before returning the second otparyvali gas containing otvarennuyu acrylic acid in the condensation column and/or translate otvarennuyu acrylic acid contained in the second otpaivaem gas into an aqueous solution of a metal hydroxide, a second otparyvali the gas is subjected to countercurrent rectification.

14. The method according to one of PP-13, characterized in that the first odarivaemogo gas using air, nitrogen, carbon dioxide and/or water vapor.

15. The method according to one of PP-13, characterized in that the first odarivaemogo gas use residual gas mixture.

16. The method according to one of claims 1 to 15, characterized in that the crude acrylic acid is subjected to additional crystallization treatment.

17. The method according to item 16, characterized in that the crude acrylic acid before additional crystallization purification add a partial amount of non-refundable in the condensation kolonakiou water.

18. The method according to item 16 or 17, characterized in that the additional crystallization purification of crude acrylic acid or its mixture with the acidic water is carried out by suspension crystallization.

19. The method according to p, characterized in that for the separation of suspension remaining after crystallization of the mother lye and formed by suspension crystallization suspension kristalliset use the wash column.

20. The method according to one of PP-19, characterized in that after completion, perform radical polymerization, in accordance with which will copolymerize molten crystallized acrylic acid and/or its metal salt.

21. The method according to one of p, 11 or 13, characterized in that after completion, perform radical polymerization, in accordance with which will copolymerized acrylic acid, translated into an aqueous solution of a metal hydroxide from the first and/or second odarivaemogo gas containing acrylic acid.

22. The method according to one of claims 1 to 21, characterized in that a partial amount of residual gas mixture as a gas circulation loop return on gas-phase partial oxidation.

23. The method according to one of claims 1 to 22, characterized in that in the conditions of the extraction unit weight of organic solvent to ≥25 kg/m3differs from UD is through the mass of water.

24. The method according to one of claims 1 to 23, characterized in that the aqueous solution of metal hydroxide contains dissolved sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2and/or magnesium hydroxide (Mg(OH)2).

25. The method according to one of claims 1 to 24, characterized in that the condensation column between the first side selection and the second side selection serves liquid absorbent, the boiling temperature TSwhich at atmospheric pressure is higher than or equal to the boiling temperature TWwater at atmospheric pressure.

Provisional application for U.S. patent No. 60/886771 from 26.01.07 and No. 60/988619 from 16.11.07 included in the present description as a reference. In respect of the above technical solutions are possible numerous changes and deviations from the present invention. Thus, it is necessary to consider, that the invention in accordance with the following formula may differ from the above description.

Examples and comparative example

Example 1 (stationary mode)

In three parallel operating lines, consisting of the twin reactors, two-stage heterogeneously catalyzed gas-phase partial oxidation of propylene brand "chemically pure" get having a temperature of 270°C. and a pressure of 1.5 bar total gas mixture of the reaction product of the following composition is:

10,3141% of the mass.acrylic acid
0,2609% of the mass.acetic acid
4,6513% of the mass.water
0,0251% of the mass.formic acid
0,0851% of the mass.formaldehyde
0,1052% of the mass.acrolein
0,0024% of the mass.propionic acid
0,0028% of the mass.furfural
0.0012% of the mass.allylacetate
0,0013% of the mass.alifornia
0,0032% of the mass.benzaldehyde
0,1151% of the mass.maleic anhydride
0,0096% of the mass.benzoic acid
0,0126% of the mass.phthalic anhydride
2,0334% of the mass.carbon dioxide
0,6604% of the mass.carbon monoxide
0,6259% of the mass.propane
0,1459% of the mass.propylene
2,3772% of the mass.oxygen and
78,5670% of the mass.nitrogen

The mixture of the reaction gases supplied to each of the three reactor lines is respectively a mixture gas circulation circuit and propylene brand "chemically pure", which is then metered primary air. Stirring is carried out in the respective mixers.

Between the reactors of the first and second stages, respectively, serves the secondary air.

The number of arriving at the first stage of the initial reagents in accordance with the operating mode of each of the reactor lines is:

A) the gas circulation circuit 25339 kg/h

chemically pure propylene 3481 kg/h

air 17791 kg/h;

B) the gas circulation circuit 38341 kg/h

chemically pure propylene 4035 kg/h

air 19561 kg/h;

C) the gas circulation circuit 30874 kg/h

chemically pure propylene 4689 kg/h

air 23936 kg/h;

The three formed the reaction gas flows:

A) 10,2909% of the mass.oxygen
1,2926% of the mass.carbon dioxide
0,4136% of the mass.carbon monoxide
0,6533% of the mass.propane
7,2976% of the mass.propylene
1,5383% of the mass.water and
78,2693% of the mass.nitrogen
In) 8,9782% of the mass.oxygen
1,4660% of the mass.carbon dioxide
0,4710% of the mass.carbon monoxide
0,6744% of the mass.propane
6,3907% of the mass.propylene
1,6626% of the mass.water and
80,0789% of the mass.nitrogen
C) 10,6981% of the mass.oxygen
1,2357% of the mass.carbon dioxide
0,3948% of the mass.0,6500% of the mass.propane
7,6922% of the mass.propylene
1,4968% of the mass.water and
77,5992% of the mass.nitrogen

The gas mixture of the reaction products (177184 kg/h) is cooled to a temperature 107,3°C by direct cooling direct flow irrigation cooler (node hardening 1).

The liquid to be used for direct cooling of the gas mixture of the reaction products (hardening liquid 1)represents a partial amount of the mixture 1 comprising selected from Cuba described below condensation columns cubic liquid and a small amount (251 kg/h) taken from the quenching circuit 0 condensate.

A mixture of 1 with temperature 104,9°C has the following structure:

In irrigation cooler quenching circuit 1 for direct cooling serves 458 m3/h of a gas mixture of the reaction products having the above temperature. at 3,137 kg/h serves the second Stripping column and 1195 kg/h in the quenching circuit 0 for inhibiting undesirable polymerization hardening liquid 0 and phlegmy directed to the upper plate of the second is tarnai columns.

The resulting direct cooling, the mixture cooled to 107,3°With the gas mixture of the reaction products and not evaporated hardening liquid 1 as such is sent to the cube of the condensation column. The pressure in the VAT amount and site hardening 1 is 1.50 bar.

The inner diameter of the condensation column in the zone of location of the plates of Torman is 6.5 m, in other parts of the column 6,0 m

at 3,137 kg/h of a mixture of 1 served in the second Stripping column, which is as effectively separating the built-in elements contains 50 double-flow plates. The second Stripping column, similar to the condensation column is equipped with exterior insulation. The inner diameter of the second Stripping column in the area of twin plates is 2.4 m double-flow plates are in the second Stripping column at equal distances from each other (400 mm). The ratio of D:U (see above) for all plates is 12%. The diameter of the holes of the first eight double-flow plates (in the upward direction) is 14 mm (holes are located strictly in accordance with triangular gradation; the distance between the centers of adjacent holes 26 mm); diameter of holes all subsequent double-flow plates also is 14 mm (holes are also strictly in accordance with triangular gradation; Russ is the right between the centers of adjacent holes is 25 mm).

On the first bottom eight double-flow plates arrives at 3,137 kg/h of a mixture of 1 with a temperature of 105.2°C.

The flow of energy in the second Stripping column is realized by means of external expansion shell-and-tube heat exchanger with forced circulation (see Grundoperationen chemischer Verfahrens-technik, 4th edition, publisher Steinkopff, Dresden, 1974, s). In the evaporator is directed 271650 kg/h taken from the cube of the second Stripping column bottom liquid temperature 151,7°C and pressure 1,655 bar, which has the following structure:

As the flow rate through the space zigzag form with the appropriate reflective walls surrounding the tubes of the heat exchanger, pass water vapor under a pressure of 16 bar. When passing through the tubes of the heat exchanger waste liquid is heated, and 270900 kg/h of the total number passed through a heat exchanger bottom liquid temperature 158,6°C return to the cube of the second Stripping column. 750 kg/h of the total number passed through a heat exchanger bottom liquid divert, dearyou, diluted with methanol and sent for incineration of industrial waste.

Additionally to the cube of the second Stripping column serves 17424 kg/h is withdrawn from the top of the first Stripping column containing acrylic acid gas with temperaturas,2°C and a pressure of about 2,50 bar, which has the following structure:

3,3977% of the mass.acrylic acid
1,1198% of the mass.acetic acid
4,1030% of the mass.water
0,0622% of the mass.formic acid
0,0321% of the mass.formaldehyde
0,1181% of the mass.acrolein
0,0030% of the mass.propionic acid
0,0006% of the mass.furfural
0,0139% of the mass.alifornia
0,0247% of the mass.diethyl ether phthalic acid
2,5667% of the mass.oxygen
2,1951% of the mass.carbon dioxide
0,7129% of the mass.carbon monoxide
0,6756% of the mass.propane
0,1575% of the mass. propylene and
84,8133% of the mass.nitrogen

From the top of the second Stripping column output 25831 kg/h of the second containing acrylic acid gas (temperature 96,7°C, pressure 1,58 bar), which by direct cooling in counter-flow irrigation cooler (node hardening 0) is cooled to a temperature of 80.9°C and partially condense.

20755 kg/h remaining after direct cooling of the gas mixture of the following composition with pressure 1,58 bar return in the cubic part of the condensation column (flow over the mirror bottom liquid):

18,5793% of the mass.acrylic acid
0,9849% of the mass.acetic acid
3,6185% of the mass.water
0,0571% of the mass.formic acid
0,0271% of the mass.formaldehyde
0,1006% of the mass.acrolein
0,0099% of the mass.propionic acid
0,0436% of the mass.furfural
0,0003% of the mass.allylacetate
to 0.0117% of the mass.alifornia
0,0053% of the mass.benzaldehyde
0,0642% of the mass.maleic anhydride
0,0001% of the mass.benzoic acid
0,0001% of the mass.diacrylates acid
0,0001% of the mass.p-methoxyphenol
2,1548% of the mass.oxygen
1,8428% of the mass.carbon dioxide
0,5985% of the mass.carbon monoxide
0,5672% of the mass.propane
0,1322% of the mass.propylene and
71,2018% of the mass.nitrogen

As the hardening liquid 0 use 32956 kg/h of a mixture consisting of 1195 kg/h of a mixture of 1 and 37761 kg/h of condensate formed in the host hardening of 0 for direct cooling (specified partial amount of the mixture cool water convenablement spiral type with 80,9 to 40.1°C). 6020 kg/h of this mixture with a temperature of 80.9°C as phlegmy sent to the top tray of the second Stripping column.

The mixture has the following composition:

As the volume of the condensation column mounted centrifugal droplet separator, which prevents the drift bottom liquid from the cube column in its upper part.

As indicated above, the VAT amount of the condensation column terminates at 7.80 m (all levels counted from the bottom of the cube) of the first absorbing plate (cumulative plate; the plate chimney type with sixteen almost evenly distributed conditional fireplaces, a diameter of 600 mm, height 1 m).

Cumulative plate has double walls with inward angle of 2° and provided with a Central exhaust valve and the exhaust nozzle (DN 200). Free gas section is about 30%.

Fraction taglocity products (88579 kg/h) with the specified first catching plates comes in below her CC volume.

Fraction taglocity products with temperature is 99.8°C and a pressure of about 1,50 bar has the following structure:

0,5402% of the mass./tr>
94,6665% of the mass.acrylic acid
acetic acid
1,3577% of the mass.water
0,0160% of the mass.formic acid
0,0014% of the mass.formaldehyde
0,0071% of the mass.acrolein
0,0577% of the mass.propionic acid
0,3814% of the mass.furfural
0,0023% of the mass.allylacetate
0,0010% of the mass.alifornia
0,1279% of the mass.benzaldehyde
2,1925% of the mass.maleic anhydride
0,0051% of the mass.benzoic acid
0,0046% of the mass.phthalic anhydride
0,6008% of the mass.diacrylates acid
0,0061% of the mass.fenotiazina
0,0314% of the mass.p-methoxyphenol and
is 0.0002% of the mass.oxygen

The temperature of the cube is 104,9°C, the pressure above the liquid level 1,51 bar.

At the level of 2.0 m from the first detecting plate is the first double-flow plate of fifteen such plates. Such double-flow plates (the number of holes in each of them is 33678) are at the same distance from each other, amounting to 380 mm in the Same round through holes have a diameter of 14 mm, and left after cutting burrs downward distillation column. Hole centers are strictly ordered in accordance with triangular graduation. The distance between the centers of two nearest holes is 24.5 mm

Fifteenth two plate performs the function of switch plates. In accordance with this, the walls of the column between the second catching plate and fifteenth twin plate has two plug-pipe (nominal diameter of about 150) 45 output holes with a diameter of 15 mm in each plug-in pipe.

From a point above the inserted pipes, crude acrylic acid and mother liquor return in the condensation column.

The first series of twin plates completes the second absorbing plate (cumulative plate; the plate chimney type with sixth is NADZORU almost evenly distributed conditional fireplaces height of about 1.70 m equipped with an outlet nozzle (orifice 250) Central shutter and free gas section of about 30%), which is at 1.50 m above the last two-flow plates.

With the specified second capture plates at a pressure of 1.48 bar as the first side selection continuously selected crude acrylic acid with temperature to 97.1°C, which has the following structure:

96,7716% of the mass.acrylic acid
0,8253% of the mass.acetic acid
1,6640% of the mass.water
0,0213% of the mass.formic acid
0,0018% of the mass.formaldehyde
0,0070% of the mass.acrolein
0,0681% of the mass.propionic acid
0,1642% of the mass.furfural
0,0027% of the mass.allylacetate
0.0012% of the mass.alifornia
0,0164% of the mass.benzaldehyde
0,1052% of the mass.maleic anhydride
0,3278% of the mass.diacrylates acid
0,0050% of the mass.fenotiazina
0,0180% of the mass.p-methoxyphenol and
is 0.0002% of the mass.oxygen

18474 kg/h of crude acrylic acid selected from the second capture plates, together with 72716 kg/h fallopian liquor generated in the process of crystallization purification of selected crude acrylic acid and heated in the indirect heat exchanger is used as a coolant selected crude acrylic acid and water vapor up to 90°C, return in the condensation column through the above mentioned insertable pipe on a two-line plate located under the second catching plate.

89303 kg/h of crude acrylic acid selected from the second capture plates, by indirect heat exchange is subjected to multi-stage cooling to a temperature of 29°C (in particular, with heat recovery above the mother lye for return of the condensation column) and, if necessary, are sent to intermediate storage in the corresponding reservoir. Then to the cooled crude acrylic acid is added 1204 kg/h KIS the Oh water, taken from the second side of the selection of the condensation column.

Acidic water has the following composition:

10,7677% of the mass.acrylic acid
6,4390% of the mass.acetic acid
79,5610% of the mass.water
0,7038% of the mass.formic acid
2,4712% of the mass.formaldehyde
0,0132% of the mass.acrolein
0,0082% of the mass.propionic acid
0,0013% of the mass.furfural
0,0331% of the mass.alifornia
0,0001% of the mass.p-methoxyphenol and
0,0013% of the mass.oxygen

The resulting mixture by repeated indirect heat exchange (counterflow cooling brine, which is a mixture of from 25 to 35% of the mass. glycol and from 65 to 75% of the mass. water) is cooled to 16°C and sent in two or three parallel function.imagecreatetruecolor with most of the disks (see international application WO 2006/111565). The concern of the respective vats, each of which is at the same distance from each other of 30±1 cm, 24 are successively suspended pureed all the cooling fins with a diameter of 3.3 m (within each plate is flowing cooling medium, which is a mixture of water and glycol from the glycol and water mixture from 25 to 35 wt. -%). In this case, the respective cooling medium is moved through the respective mold from one of the cooling of the disc above it another cooling disk countercurrent with respect to the crystallizing mixture. Appropriate cooling medium is passed through the cooling fins of the respective mold in the form of two parallel threads. One stream is passed through an even cooling fins, while the other stream is passed through an odd cooling fins (the numbering of the plates begins with one and corresponds to the direction of flow). The total flow rate of cooling medium through each mold is from 180 to 220 t/h (90 to 110 t/h on one thread). The pressure loss for each of the cooling disk is 60 to 100 mbar. The temperature of the cooling medium at the inlet is from +2.5 to +3°C. the Temperature of the cooling medium at the outlet 2.5°C higher than the temperature of its input. The thickness made of special steel ohla the giving of planes is 4 mm The heat transfer coefficient of brine is in the approximate range from 1500 to 2500 W/(m2·K). The values of heat transfer coefficient in the majority of cases are in the range from 380 to 420 W/(m2·K). Specific cooling capacity is 1.5±0.2 kW/m2a cooling surface. Wiping cooling plates prevents the formation of a layer of crystals. Moist crude acrylic acid is continuously passed through the corresponding crystals with regulation overflow via a pump. When this occurs, the seal single-phase hydrated crude acrylic acid (the residence time of 2.5 h) to two-phase suspension containing the solid phase crystals of acrylic acid, with temperatures ranging from 7 to 8.5°C and the solids content in the yield of about 25% of the mass. The specific weight of the suspension usually corresponds to the interval from 1110 to 1115 kg/m3. The rotation speed of the wiper plates is 5 to 6 rpm passed through the centers of cooling drives the drive shaft is provided with a wash water Salnikov seal (gland packing as Teflon or graphite cord, the flow of wash water from a few liters to several tens of liters per hour per seal).

Along the perimeter of the cooling disks that cannot be cleaned, fixed hollow profile (in the simpler version, for example, weldable tube)is heated by the second heat carrier (for example also a mixture of water/glycol) to a temperature exceeding the crystallization temperature and in most cases in the range from 8 to 20°C, preferably from 10 to 14°C. the second fluid forms a parallel heat flow.

In addition, cleaners cooling plates in the radial direction is preferably segmented (four segments). Specific contact pressure cleaners in assembled condition, acting normal to the cooled plane, is from 3 to 5 N/cm active length rubbing edges. As the material of cleaners cooling plates using polyethylene of high molecular weight or brand of polyethylene ultra-high molecular weight, for example Multilene®RE 1000. In addition to cleaners shaft causes the rotation of the blades also providing better mixing, and between each two, and before the first and the last cooling disks accordingly, it is advisable to have two symmetrically arranged blades.

To the rear side of the respective mold in the direction of movement of the suspension (preferably after the last cooling disk) is adjacent the pipe (in a suitable embodiment, it is shipped in is Uspenskiy; in another embodiment, the suspension through the overflow device can flow into the collection with an agitator, where it is directed into the washing column)on which the suspension order branch of the uterine liquor suspended from kristalliset send in the hydraulic column for washing the melt is described in European patent application EP AND 1272453 and EP AND 1448283, international application WO 03/041833, European patent application EP AND 1305097, as well as in the German patent applications DE A 10156016, DE A 102005018702 and DE A 10223058. The diameter of wash columns is 1.4 meters the Flow of a suspension of crystals in the wash column is realized by means of a centrifugal pump (type tunnel wheels), and the flow rate of the suspension regulate preferably by varying the pump speed. Flow in-line pump control is executed also in the form of a circuit with control valve. Used for regulation of the wash column, the flow rate of the suspension in line management is usually from 5 to 60 t/h, in most cases, from 8 to 30 t/h In the case where the flow rate of the liquid contained in the feed in the wash column suspension, sufficient to transport crystal layer corresponding to wash the column sometimes can be operated without the use of control flow. The ratio of the pressure drop, which provides transport to drop D. the effect, providing a flushing operation is usually from 1.1:1 to 3:1, in most cases, from 1.2:1 to 1.8:1. Speed knife in most cases is 5 to 10 rpm, the Temperature in the path of the melt is usually from 13 to 16°C. the Control front filtration according to the German patent application DE A 102005018702 through two matched each other of the results of the measurement of the differential pressure areas of the layer of variable length. Front washing regulate by measuring the temperature in the crystalline layer.

The total height of the crystal layer depending on the nature of regulation varies from 250 to 1500 mm, in most cases from 600 to 1100 mm Front leaching in typical cases is above the knife in the amount of from 100 to 200 mm as pump circuit suitable melt centrifugal pump with flushing shaft seal from the melt (double contact sealing ring with cooled to a temperature of from 15 to 30°C sealing medium (a mixture of water/glycol) or a pump with electromagnetic clutch and a system of intensive leaching bearings). Volume circulating in the corresponding contour of the melt is from 10 to 15 m3/h per ton removed with a knife purified kristalliset. Depending on the destination of acrylic acid and constructionone stabilization of the melt in the circuit is implemented by p-methoxyphenol, used in a concentration of from 200 to 300, or from 40 to 70 wt. parts per million, or fenotiazina used in a concentration of from 100 to 300 wt. parts per million In the circuit of the melt is additionally serving the air or lean air (a mixture of nitrogen with air containing less than 6% vol. oxygen), the excess of which (not soluble in the wash melt part) before entering the wash melt in the wash column is separated by the gas separator. As a result, the dissolved oxygen in the molten pure product is from 5 to 40 wt. parts per million-.

[a) the purpose of receiving suitable for the esterification of acrylic acid allocation of appropriate suspension kristalliset can be done not in the column for washing the melt, and by means of a centrifuge (e.g., two-stage or three-stage pulse centrifuge). Suitable are sieves with mesh size of 150 to 300 microns, suitable centrifugal acceleration ranges from 500 to 900 g in most cases from 600 to 800 g suitable number of strokes per minute ranges from 40 to 80.

For washing one kilogram of crystals allocated to the second or third stage centrifuge, preferably using from about 0.15 to 0.3 kg of washing fluid. The temperature of the washing liquid is from 15 to 30°C, preferably from 20 to 0°C. To avoid sedimentation of the channel for the release of solids from the centrifuge washed with a wash liquid, cooled in the temperature range from 15 to 30°C. as the washing and rinsing liquids preferably uses allocated on a centrifuge and washed molten crystallized. To avoid the formation of deposits and crystalline crusts of the centrifuge housing, a pipe for supplying the suspension and a pipe for supplying washing liquid into a suitable variant thermostatic in the temperature range from 15 to 40°C. the working volume of the centrifuge, it is advisable to inarticulate via a nitrogen or a mixture of air and nitrogen. The shaft seal purge gas (e.g. nitrogen or a mixture of air and nitrogen) or washed with water.

b) In another embodiment, for the suspension crystallization can also use the technology layer-by-layer crystallization (for example, crystallization with a falling film according to the European patent application EP AND 616998 or crystallization in the pipe with a continuous through-flow) with two, three or more (for example, from two to four) stages of cleaning. Instead of returning the mother lye with subsequent purification stages in the previous it can be returned together in the condensation column.]

From the contours of the circulation of the melt stabilized by adding the value at 25°C and a pressure of 1.1 bar solution (104 kg/h) p-methoxyphenol (3 kg/h) taken from the paths of circulation of the molten pure acrylic acid (101 kg/h) 25°C, select 17894 kg/h of pure acrylic acid (temperature 14°C, pressure of 1.5 bar), which has the following structure:

99,7334% of the mass.acrylic acid
0,2091% of the mass.acetic acid
0,0180% of the mass.water
0,0230% of the mass.propionic acid
0,0001% of the mass.furfural
<0,0001% of the mass.benzaldehyde
0,0001% of the mass.maleic anhydride
is 0.0002% of the mass.diacrylates acid
0,0150% of the mass.p-methoxyphenol and
0.001% of the mass.oxygen

Acrylic acid of the above composition is perfectly appropriate for superabsorbers based polyacrylate.

For cooking having a temperature of 25°C solution of inhibitor 1 in 352 kg/h above the heated pure acrylic acid is dissolved 5 kg/h fenotiazina. For cooked the I with a temperature of 25°C solution of inhibitor 2 19 kg/h of a p-methoxyphenol dissolved in 30 kg/h of a solution of inhibitor 1.

17439 kg/h stabilized by p-methoxyphenol pure acrylic acid with a temperature of 25°C and a pressure of 1.5 bar is continuously fed into the tank for storage.

Highlighted in leaching columns uterine liquor first direct heated in the collector, from which it enters the storage tank. 72716 kg/h fallopian liquor from the tank, heated to 90°C. through the above heat recovery systems, together with 18474 kg/h taken from the second capture plates crude acrylic acid back into the condensation column on the fifteenth dual stream bottom plate. Such return uterine liquor has the following composition:

94,6188% of the mass.acrylic acid
1,0690% of the mass.acetic acid
3,3562% of the mass.water
0,0378% of the mass.formic acid
0,0431% of the mass.formaldehyde
0,0088% of the mass.acrolein
0,0782% of the mass.propionic acid
0,2016% of the mass.furfural
0,0034% of the mass.allylacetate
0,0021% of the mass.alifornia
0,0202% of the mass.benzaldehyde
0,1292% of the mass.maleic anhydride
0,4025% of the mass.diacrylates acid
0,0061% of the mass.fenotiazina
0,0227% of the mass.p-methoxyphenol and
0,0003% of the mass.oxygen

In the condensation column on the second catching plate at a distance of 2.9 m from it is the first of 21 twin plates of the type indicated above (hole diameter 14 mm, number of holes 32020, the distance between the centers of two adjacent holes of 24.5 mm), which are at the same distance from each other, comprising 380 mm

At the level of 800 mm above the level of the last two-flow plates, begins conical extension of the condensation column. Conical extension terminates at a distance of 500 mm from the last two-flow plates (inner dia is the Tr column in this place is 6,50 m).

At the indicated level (1.50 m above the last two-flow plates) begins a series of 28 located at the same distance from each other (500 mm) conventional single-threaded plates of Torman. The first bottom plate of Torman has a design, in accordance with which the liquid flows with her six drain pipes as pipes. Pipes are hydraulically sealed relative to the gas space below the double-flow plates. Packing height of six drain pipe is reduced in the direction of the flow plates with cross-current. Hydraulic seal with openings idle mode with the reflective plates. Drain pipe evenly distributed in the last third of the cross-section of the plate (opposite the feed side). Hydraulic seal implement through the gate with sloped overflow device (angle 45°).

In addition, plates of Torman have a design, whereby by placing in their housings injection slits in the grooves sequentially disposed in the direction of the cross flow is formed corresponding to oncoming fluid flow.

The ratio of D:U (see above) for plates of Torman is 14%. The ratio of the area of the fireplace to the outlet cross section of the slots of the composition is employed to 0.8. The height of the fireplace and the height of the discharge pipe respectively 40 mm Gap caps (the distance between the lower edge of the slot and plate) is 10 mm, the Height of the slots is 15 mm, the Angle between the expanding slot and the longitudinal edge of the casing is 30 degrees. The maximum length of a longitudinal edge of the casing is 800 mm In the inner edge zones of the column length of the casing is reduced to 200 mm, because of the need to bring the configuration into compliance with the curvature of the column. The distance between two covers that are on the same line in the direction of flow, is 66 mm Square bore drain pipe is 1.5% of the cross-sectional area of the plates. The distance between the two lower longitudinal edges of the casing is 64 mm.

At the level corresponding to the top plate of Torman again begins conical narrowing of the distillation column. Narrowing terminates at a level located at 700 mm above the top plate of Torman (diameter of the column in this place again is 6.00 m).

At the height of 1.70 m above the upper plate of Torman is the third absorbing plate (cumulative plate, the plate chimney type with sixteen almost evenly distributed conditional fireplaces height 1.50 m).

Third detecting that the Christmas tree as the second side of the selection output 535506 kg/h of acid water with a temperature of 65.1°C and a pressure of about 1,24 bar.

Acidic water has the above composition:

10,7677% of the mass.acrylic acid
6,4390% of the mass.acetic acid
79,5610% of the mass.water
0,7038% of the mass.formic acid
2,4712% of the mass.formaldehyde
0,0132% of the mass.acrolein
0,0082% of the mass.propionic acid
0,0013% of the mass.furfural
0,0331% of the mass.alifornia
0,0001% of the mass.p-methoxyphenol and
0,0013% of the mass.oxygen

25537 kg/h selected acidic water with a temperature of 65.1°C together with a solution of inhibitor 2 return to the top plate of Torman.

329 kg/h of a solution of inhibitor 1 with a temperature of 25°C return on nineteenth bottom plate of Torman.

316 kg/h selected acidic water is directed to SIG the interview.

310 m3/h selected acidic water with a temperature of 29.1°C return to the sixth bottom below valve plate (cooling sour water is carried out by a multi-stage indirect heat exchange).

194011 kg/h selected acidic water with a temperature of 23°C return to the topmost described below valve plate (it is cooled together with the above-mentioned amount of acidic water by multi-stage indirect heat exchange, cooling from 29.1 to 23°C in the last step carried out separately with simultaneous heat recovery (as a cooling agent used in this evaporated liquid chemically pure propylene; formed gaseous propylene is then used to form a mixture of reaction gases intended for gas-phase partial oxidation)).

1204 kg/h selected acidic water, as described above, is added to the crude acrylic acid to be additional crystallization treatment.

6010 kg/h selected acidic water is directed to the extraction column for subsequent proposed in the invention of extraction.

At the level of 2300 mm above the third catching plates in the condensation column at equal distances from each other (500 mm) are eleven double-flow valve trays. The height of the respective drain pipes SOS the place from 18 to 35 mm (to top plates it more than the bottom). The ratio of D:U (see above) is 14.8%, the total flow section of the discharge nozzles of two consecutive valve plates is about 10% of the cross-sectional area of the column. As the valve using the valve W12 firm Stahl (Germany, Bernheim).

The pressure in the upper part of the column is at 1.17 bar. From the upper part of the column output 170121 kg/h of residual gas with a temperature of 31°C, which has the following structure:

0,1946% of the mass.acrylic acid
0,1246% of the mass.acetic acid
2,3031% of the mass.water
0,0062% of the mass.formic acid
0,1212% of the mass.acrolein
is 0.0002% of the mass.propionic acid
0,0001% of the mass.furfural
0,0027% of the mass.alifornia
2,3427% of the mass.carbon dioxide
0,7609% of the mass. carbon monoxide
0,7211% of the mass.propane
0,1681% of the mass.propylene
2,7387% of the mass.oxygen and
90,5158% of the mass.nitrogen

The residual gas is heated in the indirect heat exchanger to 38°C, after which 110880 kg/h specified residual gas is compressed by the compressor for the gas circulation circuit to 2.9 bar, and the temperature rises to about 160°C. 94553 kg/h of compressed residual gas back to the gas-phase partial oxidation as a gas circulation loop. 16327 kg/h of compressed residual gas is directed into the first Stripping tower with the aim of steaming extract the extraction unit, sour water, while 59241 kg/h of residual gas is sent for incineration.

The extraction column, designed for the extraction of acidic water, as effectively separating the built-in elements arranged one above the other perforated structured nozzle type Montz-Pak B1-350 with active total height of 10 m (the height of the nozzle is 200 mm, the nozzle is made of a special sheet steel 1.4571).

The internal diameter of the extraction columns regardless of t the PA used nozzles is 800 mm The height of the extraction column is 14 meters as extractant use the product Palatinol®A. its bottom and the upper part of the extraction column is expanded to a diameter of 1100 mm, which promotes a more efficient separation of the phases in Cuba and reduces the ablation of the extracting agent in the upper part of the column. In addition, as used to reduce coalescence AIDS in the upper part of the column is Packed layer of particles of polymer filler (for example, polyethylene or Teflon).

Filing 6010 kg/h subject to extraction of acidic water with a temperature of 65.1°C carried out below the lower nozzle extraction columns through the corresponding through holes of the distribution manifold, the diameter of which is 8 mm Above the top nozzle extraction columns serves a mixture of approximately 25 kg/h of fresh product Palatinol®A and 5987 kg/h return from the first Stripping column and otvarennogo it extracting agent to a temperature of 50°C.

Return extracting agent has the following structure:

≤0.5% mass.acrylic acid
≤0,03% of the mass.acetic acid
≤0,02% of the mass.water
≤0.001% of the mass.formic acid
≤0,0035% of the mass.acrolein
≤0,0005% of the mass.propionic acid
≤0.001% of the mass.furfural
≤0.001% of the mass.alifornia
0.03% of the mass.p-methoxyphenol
0,0001% of the mass.oxygen and
GE; 99.5% of the mass.Palatinol®A

The specific gravity of the acid water is 967,5 kg/m3. Extracting agent is also fed through the corresponding through holes of 4 mm diameter of the discharge header.

Acidic water forms a continuous phase, while the extracting agent forms are in the form of droplets of the dispersed phase (the diameter of the droplets ranges from 2 to 5 mm), rising in the aqueous phase.

From the top of extraction column select 4930 kg/h of product purification (temperature about 57,6°C), which has the following structure:

1,7618% of the mass. acrylic acid
4,3046% of the mass.acetic acid
90,1197% of the mass.water
0,6446% of the mass.formic acid
2,8993% of the mass.formaldehyde and
0,27% of the mass.Palatinol®A

Together with subject to combustion of residual gas it is sent for incineration.

From the cube extraction columns are selected 7090 kg/h of extract to a temperature of about 64,5°C, which has the following structure:

8,1556% of the mass.acrylic acid
2,4838% of the mass.acetic acid
4,7901% of the mass.water
0,1490% of the mass.formic acid
0,0788% of the mass.formaldehyde
0,0140% of the mass.acrolein
0,0073% of the mass.propionic acid
0,0014% of the mass.furfural
0,0282% of the mass.alifornia
0,0192% of the mass.p-methoxyphenol and
84,2726% of the mass.Palatinol®A

The entire quantity of the extract is sent to the top of the first Stripping column. The extract was subjected to preliminary indirect temperatures up to 95°C in a plate heat exchanger. At the same time as the coolant using 5987 kg/h taken from the first Stripping column bottom liquid. As effectively separating the built elements of the first Stripping column contains five double-flow plates and fifteen plates of Torman. Similarly, the extraction column of the first Stripping column equipped with an external insulation. The inner diameter of the first Stripping column at the level of all plates is 1.5 meters

The height of the first Stripping column is 14.5 meters Five most bottom plates are double-flow plates located at a distance of 500 mm from each other. The ratio of D:U (see above) for all double-flow plates is 18%. The diameter of the holes for all double-flow plates is 14 mm (holes are located strictly in accordance with triangular gradation). Enter the very top of a twin plates are fifteen single-threaded plates of Torman, which are at the same distance from each other (500 mm). Plates of Torman have a design, whereby by placing in their housings injection slits in the grooves sequentially disposed in the direction of the cross flow is formed corresponding to oncoming fluid flow. The ratio of D:U (see above) is 14%.

Above the last plate is used as a drip pan bulk layer is made of metal rings Poll height 400 mm (ring 25×25).

In the first Stripping column below the lowermost double-flow plates served 13000 nm3/h compressed residual gas pressure of about 2.9 bar and a temperature of about 160°C, which rises countercurrent with respect to flowing along the Stripping columns to extract.

From the top of the first Stripping column output 17424 kg/h of the first containing acrylic acid gas with temperature and 82.2°C which is sent to the second Stripping column. The temperature in Cuba the first Stripping column is about 155°C. From the cube first Stripping column is continuously selected 49311 kg/h bottom liquid. 5987 kg/h taken from the cube first Stripping column bottom liquid is cooled to 50°C. by a two-stage indirect heat exchange (the first step to implement in a plate heat exchanger by the providing to recover heat counterflow cooling the extract) and return in the upper part of the extraction columns. 43324 kg/h taken from the first Stripping column bottom liquid is heated to 160°C in an external secondary heat exchanger with forced circulation and return to the cube of the first Stripping column.

Comparative example

Example perform similarly to the previous example. However, extracted in accordance with example 1 acidic water is not subjected to the extraction and burning in accordance with the prior art.

The extraction column and the first Stripping column is missing. For steam taken from the condensation column bottom liquid used an appropriate amount of compressed residual gas. Through the first side selection unload the flow of crude acrylic acid (87307 kg/h), containing 96,863% of the mass. acrylic acid.

Sent to the storage tank for the amount of pure acrylic acid is 16994 kg/H. the Degree of purity of the corresponding acrylic acid is 99,736% of the mass.

Example 2

In a thermostatted water vessel with an internal volume of 1.3 liters, equipped with a jacket and two three-bladed stirrer at 50°C was downloaded 498 g of acidic water without inhibitor to a temperature of 50°C, which had the following composition:

2,19% of the mass.formaldehyde
82,00% of the ACC. water
4,01% of the mass.acetic acid
11,09% of the mass.acrylic acid
0.69% of the mass.formic acid and
0.01% by mass.diacrylates acid

Then under stirring was added 499 g dimethylphthalate temperature which was 50°C. the Resulting mixture was stirred for 10 minutes at a constant temperature (50°C) and the rotation speed of the mixer 250 rpm/min After switching off the stirrer, the mixture was stirred at 50°C, and after a short time was the separation of the phases. The weight of the organic phase was 565 grams, the weight of the aqueous phase 432, According to the results of gas chromatographic analysis of the aqueous phase it contained 20,26 g of acrylic acid and 13.0 g of acetic acid.

Example 3

For the extraction of acrylic acid sour water used glass extraction column. Acidic water that does not contain polymerization inhibitors, had the following composition:

2.36 per cent of the mass.formaldehyde
83,12% of the mass.water
3,98% of the mass.acetic acid
9,70% of the mass.acrylic acid
0,68% of the mass.formic acid and
0.01% by mass.diacrylates acid

The extraction column thermostatically through passed through her shirt water with a temperature of 60°C. as effectively separating the embedded element extraction column contained structured nozzle body from the special sheet steel 1.4404 (perforated nozzle type B1-350 firm Montz). The internal diameter of the extraction columns in its completed nozzle part was 40 mm cube column was applied to 10 kg/h of an aqueous solution with a temperature of 60°C. In the upper part of the countercurrent extraction columns were applied to 10 kg/h is used as the dispersed phase of diethylphthalate with droplet size from 4 to 5 mm (60°C). The output from the upper part of the column of water cleaning product contained 0.8% of the mass. acrylic acid and 2.9% of the mass. of acetic acid. Thus, the content of acrylic acid in acidic water could be increased to 93.3% of the mass. (in terms of its original mass number), and the content of acetic acid to 41% of the mass. In PR is the product purification was present at 0.2% of the mass. dissolved diethylphthalate.

Example 4

Repeating example 3. As the extracting agent and the dispersed phase in the upper part of the extraction columns were filed 27.5 kg/h dimethylphthalate (temperature 60°C, the droplet size of 4 to 5 mm). Acidic water with a temperature of 60°C, at the same time supplied to the cube of the column as a continuous phase (27.5 kg/h)had the following composition:

2,77% of the mass.formaldehyde
82,82% of the mass.water
was 4.02% of the mass.acetic acid
at 9.53% of the mass.acrylic acid
0,63% of the mass.formic acid and
0.05% mass.diacrylates acid

Coming from the top of extraction column water cleaning product contained 0.2% of the mass. acrylic acid and 2.4% of the mass. of acetic acid. Thus, the content of acrylic acid in acidic water could be increased to 98.3% of the masses. (in terms of its original mass number), and the content of acetic acid to 51.5% of the mass. Cleaning product contained 0.9% wt. dissolved dietista the ATA.

Example 5

The example was performed as in example 1. In addition to phlegm (acidic water) together with her and at the same temperature in the condensation column as an additional absorbent was applied to 1000 kg/h of water. As a result the content of furfural in the crude acrylic acid, of the output from the second capture plates condensation column as the first side selection decreased with 0,1642% of the mass. (example 1) to 0,1225% of the mass.

Example 6

The example was performed as in example 1. In addition to phlegm (acidic water) together with her and at the same temperature in the condensation column as an additional absorbent gave 5000 kg/h of water. As a result the content of furfural in the crude acrylic acid, of the output from the second capture plates condensation column as the first side selection decreased with 0,1642% of the mass. (example 1) to 0,1125% of the mass.

1. The method of obtaining acrylic acid, whereby by carried out at elevated temperature heterogeneously catalyzed gas-phase partial oxidation with molecular oxygen of at least one of the corresponding starting compound with three carbon atoms in the solid aggregate state catalysts receive a gas mixture of products containing acrylic acid, water vapor and by the components, the temperature of this mixture, if necessary, reduced by direct and/or indirect cooling, after which this mixture is sent to feature effectively separating the elements of the condensation column, along which she rises while passing fractional condensation, and through the first side selection above the place of supply of the gas mixture of the reaction products of the condensation column, the condensation column deduce depleted water and side components of the crude acrylic acid as the target product, through above the first side of the second selection the selection of the liquid phase from the condensation column display containing acrylic acid and side components of the acidic water from the upper part of the condensation the columns display the residual gas mixture containing side components boiling at lower temperatures than water, from a cube condensation column deduce cubic liquid containing acrylic acid and by-products and side components boiling at a higher temperature than acrylic acid, partial extraction quantity of acidic water as such and/or after cooling return in the condensation column as phlegmy and the crude acrylic acid, if necessary, subjected to more the positive cleaning at least one other method of thermal separation, and, if necessary, in the crude acrylic acid before additional crystallization purification add partial extraction quantity of acidic water, characterized in that the acrylic acid contained in at least a partial amount of non-refundable in the condensation column acidic water is transferred from the acidic water in the organic solvent by running this solvent extraction, followed by formation containing acrylic acid organic extract, from which the acrylic acid is further distinguish by steaming the first otparyvali gas, and the first otparyvali gas containing acrylic acid, return in the condensation column, and/or acrylic acid contained in the first otpaivaem gas, transferred to an aqueous solution of a metal hydroxide or formed first otparyvali gas containing acrylic acid, is used as the second odarivaemogo gas for the purpose of steaming acrylic acid contained in the output of the condensation column bottom liquid, and the resultant second otparyvali gas containing acrylic acid, return in the condensation column and/or acrylic acid contained in the second otpaivaem gas is transferred into an aqueous solution of a metal hydroxide.

2. The method according to claim 1, great for the present, however, that the reference compound with three carbon atoms is propylene, acrolein or a mixture of propylene with acrolein.

3. The method according to claim 1, characterized in that the acrylic acid contained in at least 25 wt.% non-refundable in the condensation column acidic water, transferred to an organic solvent by running this solvent extraction, followed by formation containing acrylic acid organic extract, from which the acrylic acid is further distinguish by steaming the first otparyvali gas, and the first otparyvali gas containing acrylic acid, return in the condensation column, and/or acrylic acid contained in the first otpaivaem gas is transferred into an aqueous solution of a metal hydroxide or formed first otparyvali gas containing acrylic acid, is used as the second odarivaemogo gas for the purpose of steaming acrylic acid contained in the output of the condensation column bottom liquid, and the resultant second otparyvali gas containing acrylic acid, return in the condensation column and/or acrylic acid contained in the second otpaivaem gas is transferred into an aqueous solution of a metal hydroxide.

4. The method according to claim 1, characterized in that the extraction of acrylic acid from KIS the ow of water is carried out in an extraction column, which as effectively separating the built-in elements contains nozzles and/or sieve trays.

5. The method according to claim 4, characterized in that the upper part of the extraction column serves organic solvent, and in the area of its cube - acidic water, and the organic solvent falls in the form of a phase dispersed in a continuous acidic aqueous phase, or characterized in that the upper part of the extraction column serves acidic water, and in the area of its cube - organic solvent, and the organic solvent rises in the form of a phase dispersed in a continuous acidic aqueous phase.

6. The method according to claim 1, characterized in that the organic solvent contains at least one ester-based aliphatic or aromatic monocarboxylic acid having 5 to 20 carbon atoms and alcohols with 1 to 8 carbon atoms.

7. The method according to claim 1, characterized in that the organic solvent contains at least one complex fluids based on aliphatic or aromatic dicarboxylic acid with 5-20 carbon atoms and alcohols with 1 to 8 carbon atoms.

8. The method according to claim 1, characterized in that the organic solvent is dimethylphthalate, diethylphthalate, dimethyltotal, diethyl-isophthalate, terephthalate and/or diethyltartrate.

9. The method according to claim 1, characterized in that the boiling point of the organic solvent at atmospheric pressure is ≥200°C.

10. The method according to claim 1, characterized in that the steam derived from the condensation of the column bottom liquid is carried out in a fitted effectively separating the built-in elements of the Stripping column, the temperature in the cube which is from 150 to 190°C.

11. The method according to claim 1, characterized in that before returning the second otparyvali gas containing acrylic acid in the condensation column and/or translate the acrylic acid contained in the second otpaivaem gas into an aqueous solution of a metal hydroxide, a second otparyvali gas containing otvarennuyu acrylic acid, is subjected to countercurrent rectification.

12. The method according to claim 1, characterized in that the first odarivaemogo gas using air, nitrogen, carbon dioxide and/or water vapor.

13. The method according to claim 1, characterized in that the first odarivaemogo gas use residual gas mixture.

14. The method according to claim 1, wherein the crude acrylic acid is subjected to additional crystallization treatment.

15. The method according to claim 1, characterized in that the crude acrylic acid before additional crystallization purification add a partial amount of non-refundable in the condensation column acidic water.

16. The method according to 14, characterized in that the additional crystallization purification of crude acrylic key is lots or its mixture with the acidic water is carried out by suspension crystallization.

17. The method according to item 16, characterized in that for the separation of suspension remaining after crystallization of the mother lye and formed by suspension crystallization suspension kristalliset use the wash column.

18. The method according to claim 1, characterized in that a partial amount of residual gas mixture as a gas circulation loop return on gas-phase partial oxidation.

19. The method according to claim 1, characterized in that in the conditions of the extraction unit weight of organic solvent to ≥25 kg/m3different from the specific gravity of water.

20. The method according to claim 1, characterized in that the aqueous solution of metal hydroxide contains dissolved sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2and/or magnesium hydroxide (Mg(OH)2).

21. The method according to one of claims 1 to 20, characterized in that the condensation column between the first side selection and the second side selection serves liquid absorbent, the boiling temperature Tswhich at atmospheric pressure is higher than or equal to the boiling temperature Twwater at atmospheric pressure.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of transferring a liquid monomer phase extracted from a storage vessel to the tank of a refueller or tanker. Described is a method of transferring a monomer phase extracted from a storage vessel, wherein monomer content is ≥ 90%, into the tank of a refueller or tanker, the monomer being a monomer from a group consisting of acrolein, methacrolein, acrylic acid, methacrylic acid, esters of acrylic acid and an alcohol having 1-12 carbon atoms and esters of methacrylic acid and an alcohol having 1-12 carbon atoms, characterised by that the liquid monomer phase on the route from the storage vessel to the tank of the refueller or tanker is subjected to at least one filtration and/or centrifuging operation in order to separate at least a portion of the polymerisation product of the monomer dissolved in the liquid monomer phase. Described also is a method for radical polymerisation of said transferred monomer phase and a method of filling the tank of the refueller or tanker with said liquid monomer phase extracted from the storage vessel.

EFFECT: safer transportation of the monomer phase by preventing undesirable radical polymerisation during transportation.

14 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of storing a monomer phase which is liquid under storage conditions. Described is a method of storing a monomer phase which is liquid under storage conditions, whose monomer content is ≥ 95%, in a storage vessel, the monomer being a monomer from a group consisting of acrolein, methacrolein, acrylic acid, methacrylic acid, esters of acrylic acid and an alcohol having 1-12 carbon atoms and esters of methacrylic acid and an alcohol having 1-12 carbon atoms, characterised by that the liquid monomer phase having been obtained by condensation from a gaseous phase or by melting of a crystalline phase, on the route from its generation into the storage vessel, is subjected to at least one filtration and/or centrifuging operation in order to separate at least a portion of the polymerisation product of the monomer dissolved in the liquid monomer phase.

EFFECT: preventing undesirable radical polymerisation during storage of the monomer phase.

11 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: method of separating acrylic and benzoic acid contained in a gas mixture of products of partial oxidation into acrylic acid, during which acrylic and benzoic acid are first converted to a liquid phase from which, using a thermal separation technique, components with lower boiling point than benzoic and acrylic acid are then separated and acrylic acid is then separated from the remaining liquid phase by crystallisation. The method does not require energy consuming separation techniques. There is basically no fusion of benzoic acid into a crystal during crystallisation, which forms the basis of marked efficiency of the procedure according to the disclosed method.

EFFECT: less energy consuming separation technique.

22 cl, 1 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for distillation purification of polymerisable compounds selected from monomers with at least one reactive double bond or other reactive functional groups, using boiling oil as an intermediate agent, which is a high-boiling, inert, long-term thermally stable substance, where the boiling oil is at the bottom of the fractionation column and boiling point of said oil ranges from 150 to 400°C at 1013 mbar, wherein the intermediate agent, without further purification, is returned into the apparatus and at most 10% of the intermediate agent per end product is taken out, and concentration of the polymerisable compound is reduced via heat exchange with boiling oil vapour in the direction towards the lower part of the column and thus in the direction of rising temperature. The method enables to prevent polymerisation of the end product. The invention also relates to use of boiling oil as an intermediate agent, which is a high-boiling, inert, long-term thermally stable substance with boiling point of 150-400°C at 1013 mbar, at the bottom of the fractionation column for distillation purification of polymerisable compounds selected from monomers with at least one reactive double bond or other reactive functional groups, wherein the intermediate agent, without further purification, is returned into the apparatus and at most 10% of the intermediate agent per end product is taken out, and concentration of the polymerisable compound is reduced via heat exchange with boiling oil vapour in the direction towards the lower part of the column and thus in the direction of rising temperature.

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6 cl, 1 dwg, 2 ex

FIELD: chemistry.

SUBSTANCE: method of extracting acrylic acid from a liquid phase uses acrylic acid as the main component and desired product and methacrolein as the by-product, where the liquid phase used is obtained via at least one fuzzy separation from a gaseous mixture of products of gas-phase partial oxidation on a heterogeneous catalyst of at least one tri-carbon precursor of acrylic acid, where the liquid phase is crystallised with enriched acrylic acid in the formed crystallised product and methacrolein in the residual liquid phase.

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14 cl, 1 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: content of acrylic aid or methacrylic acid in the liquid per total weight of liquid II is at least 10 wt %, where, along with methacrylic acid and/or acrylic acid, said liquid also contains acrolien and/or methacrolein, as well as acetone in total amount of not more than 5 wt % per total content of acrylic acid and/or methacrylic acid in liquid II, provided that liquid II was produced without adding acrolen or methacrolein in form of a pure substance of another liquid I containing acrylic acid and/or methacrylic acid, wherein liquid II, in which the weight ratio of acrolien to acetone contained therein is not equal to 3.5, liquid II is fed into the fractionation column provided that it contains at least 10 wt % acetone which inhibits polymerisation of acrylic and/or methacrylic acid, in terms of acrolein and methacrolein contained in liquid II.

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8 cl, 3 tbl, 3 ex

FIELD: mechanics.

SUBSTANCE: invention may be used for extracting residual chemical products effectively and safely. The chemical products are removed from treating devices through discharge pipes 14, 15, 16 and 17. After that under the gravity force the chemical products are collected into the common inclined collecting pipe 13 which is placed under the bottom discharge pipes. Then they are supplied to an extraction reservoir 1, which position is under inclined collecting pipe and ground level.

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6 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention refers to advanced method of production of (meth)acrylic acid ester including (meth)acrylic acid purification by contacting raw (meth)acrylic acid containing manganese as an impurity manganese, and cation-exchange resin to remove manganese. To ensure contacting raw (meth)acrylic acid and cation-exchange resin, water is pre-added to (meth)acrylic acid. Besides, the method involves reaction of purified (meth)acrylic acid and alcohol with acid catalyst added.

EFFECT: method allows preventing effectively deactivation of the acid catalyst used in etherification reaction, equipment plugging and can ensure stable ester manufacturing.

3 cl, 5 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention relates to improved method of recovering (meth)acrolein or (meth)acrylic acid, including stage of cooling of gaseous reaction mixture containing (meth)acrolein or (meth)acrylic acid obtained by reaction of catalytic oxidation in vapour phase of one or both reagents selected from (A) propane, propylene or isobutylene and (B) (meth)acrolein, with molecular oxygen or gas, containing molecular oxygen, to temperature 140-250°C; contacting of said gaseous reaction mixture with solvent, whose temperature is 20-50°C, in recovery installation for recovering (meth)acrolein or (meth)acrylic acid in solvent, where said recovery installation contains contact zone, where gaseous reaction mixture contacts with solvent, having transversal section of round form and many devices of gaseous reaction mixture supply for supplying gaseous reaction mixture into contact zone, devices of gaseous reaction mixture supply are installed in contact zone at the same height directed towards contact zone centre, gaseous reaction mixture is supplied to contact zone from devices of gaseous reaction mixture supply and is subjected to collision straight in one point of contact zone, and recovery installation does not have device which prevents direct collision of gaseous mixture supplied from devices of gaseous reaction mixture supply. Invention also relates to recovery installation for recovering (meth)acrolein or (meth)acrylic acid.

EFFECT: ensuring efficient recovering (meth)acrolein or (meth)acrylic acid from gas containing (meth)acrolein or (meth)acrylic acid, preventing polymerisation.

7 cl, 5 dwg, 4 ex

FIELD: chemistry.

SUBSTANCE: invention relates to improved method of recovering (meth)acrolein or (meth)acrylic acid, including stage of cooling of gaseous reaction mixture containing (meth)acrolein or (meth)acrylic acid obtained by reaction of catalytic oxidation in vapour phase of one or both reagents selected from (A) propane, propylene or isobutylene and (B) (meth)acrolein, with molecular oxygen or gas, containing molecular oxygen, to temperature 140-250°C; contacting of said gaseous reaction mixture with solvent, whose temperature is 20-50°C, in recovery installation for recovering (meth)acrolein or (meth)acrylic acid in solvent, where said recovery installation contains contact zone, where gaseous reaction mixture contacts with solvent, having transversal section of round form and many devices of gaseous reaction mixture supply for supplying gaseous reaction mixture into contact zone, devices of gaseous reaction mixture supply are installed in contact zone at the same height directed towards contact zone centre, gaseous reaction mixture is supplied to contact zone from devices of gaseous reaction mixture supply and is subjected to collision straight in one point of contact zone, and recovery installation does not have device which prevents direct collision of gaseous mixture supplied from devices of gaseous reaction mixture supply. Invention also relates to recovery installation for recovering (meth)acrolein or (meth)acrylic acid.

EFFECT: ensuring efficient recovering (meth)acrolein or (meth)acrylic acid from gas containing (meth)acrolein or (meth)acrylic acid, preventing polymerisation.

7 cl, 5 dwg, 4 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of preventing precipitation of fumaric acid when producing maleic acid anhydride comprising the following steps: a) absorption of maleic acid anhydride from the mixture of products obtained as a result of partial oxidation of benzene, olefins having 4 carbon atoms and n-butane, in an organic solvent or water as an absorbent, b) separation of maleic acid anhydride from the absorbent, containing fumaric acid, wherein the absorbent regenerated thus, which contains fumaric acid, is completely or partially catalytically hydrogenated and completely or partially returned to the absorption step (a), wherein fumaric acid is hydrogenated to amber acid.

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16 cl, 8 ex

FIELD: chemistry.

SUBSTANCE: invention relates to improved methods of producing aromatic carboxylic acids, involving bringing material containing at least one initial substituted aromatic hydrocarbon, where the substitutes are oxidisable to carboxylic acid groups, with oxygen gas in a liquid-phase oxidation reaction mixture containing a monocarboxylic acid as a solvent and water, in the presence of a catalyst composition containing at least one heavy metal, which is effective for catalysing oxidation of the substituted aromatic hydrocarbon to an aromatic carboxylic acid, in a reaction section at high temperature and pressure, effective for keeping the liquid-phase oxidation reaction mixture in a liquid state and forming an aromatic carboxylic acid, and impurities containing by-products of oxidation of the initial aromatic hydrocarbon, which are dissolved or suspended in the liquid-phase oxidation reaction mixture, and a high-pressure vapour phase containing a solvent - monocarboxylic acid, water and small amounts of the initial aromatic hydrocarbon and by-products; transferring the high-pressure vapour phase from the reaction section into a separation section sprinkled by a liquid reflux containing water and capable of almost completely separating the solvent - monocarboxylic acid and water in the high-pressure vapour phase to form a liquid rich in solvent - monocarboxylic acid and depleted of water, high-pressure gas containing water vapour; transferring the high-pressure gas containing water vapour from the separation section without processing to remove organic impurities into a condensation section and condensation of the high-pressure gas to form a liquid condensate containing water and exhaust gas from the condensation section under pressure, containing non-condensed high-pressure gas components, transferred into the condensation section; removal from the condensation section of a liquid condensate containing water and suitable for use without further processing as at least one liquid containing water in a method of purifying aromatic carboxylic acids; and feeding the liquid condensate containing water removed from the condensation section during purification of aromatic carboxylic acids in which at least one step includes: (a) preparing a purification reaction solution containing an aromatic carboxylic acid and impurities which are dissolved or suspended in a liquid containing water; (b) bringing the purification reaction solution containing aromatic carboxylic acid and impurities in the liquid containing water, at high temperature and pressure, into contact with hydrogen in the presence of a hydrogenation catalyst to form a liquid purification reaction mixture; (c) separating the solid purified product containing carboxylic acid from the liquid purification reaction mixture containing aromatic carboxylic acid and impurities in the liquid containing water; and (d) using at least one liquid containing water to wash the obtained purified solid aromatic carboxylic acid separated from the liquid purification reaction mixture containing aromatic carboxylic acid, impurities and the liquid containing water; such that the liquid containing water on at least one step of the purification method contains a liquid condensate containing water and which needs processing to remove organic impurities.

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

44 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of drying aromatic carboxylic acid, involving drying of aromatic carboxylic acid precipitate using a fluidised bed drier, where the precipitate is fed into the drier at a rate of 50 kg/h or higher, and a drying gas at temperature 80-160°C is fed into the drier with reduced speed of 0.3-1 m/s, so that content of liquid in the precipitate is equal to or less than 14 wt %; as well as to an improved method of obtaining dry aromatic carboxylic acid, involving continuous drying of aromatic carboxylic acid precipitate using a fluidised bed drier to obtain ready aromatic carboxylic acid, where the precipitate is fed into the drier at a rate of 50 kg/h or higher, and drying gas at temperature 80-160°C is fed into the drier at reduced speed of 0.3-1 m/s so that content of liquid in the precipitate is equal to or less than 14 wt %. The aim of the invention is to develop a method of drying aromatic carboxylic acid and a method of drying aromatic carboxylic acid, each method solving problems associated with use of a fluidised bed drier, such as clogging by crystals or aromatic carboxylic acid crystals sticking in the drier, and low efficiency of the drier.

EFFECT: ensuring stable operation of a fluidised bed drier.

8 cl, 5 dwg, 1 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of purifying acetic acid, which can be used in microelectronics, liquid chromatography, in chemical, food and medical industry. The purification method involves treating the initial acetic acid with a chemical reagent, rectification purification of the pre-treated acetic acid, where the chemical reagent used at the pre-treatment step is hydrogen peroxide with volume ratio of acetic acid to hydrogen peroxide equal to 180-220:1, where treatment is carried out while stirring at a rate of 40-80 rpm at temperature 0-20°C, and the periodic rectification step is carried out in a column filled with filtered inert gas, with reflux ratio of 20-10 with collection of the solvent stripper and 8-5 with collection of the product, at pressure 200-700 mmHg, and temperature at the bottom of the column equal to 90-120°C and 80-118°C at the head of the column.

EFFECT: obtaining a product containing 99,96-99,99 wt % basic substance and suspended particles on the level of 80-200 per cm3.

5 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of reducing concentration of aldehyde in the crude stream of a carbonylation process, involving feeding a crude stream containing a carbonylatable agent selected from a group consisting of methanol, methyl acetate, methyl formate and dimethyl ether or mixture thereof, having primary concentration of aldehydes; and reaction thereof in gaseous phase with a deposited catalyst which contains at least one metal from group 8 to 11, in conditions which facilitate reduction of primary concentration of aldehydes to secondary concentration of aldehydes.

EFFECT: method improves degree of reduction of aldehyde.

28 cl, 3 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of recovering energy during production of aromatic carboxylic acids via liquid phase oxidation of aromatic hydrocarbons wherein vapour containing reaction solvent and water forms in the top part of the reactor, and the method comprises the following steps: a) high efficiency separation of the vapour from the top part of the reactor to form at least a high-pressure gas stream containing water and organic impurities; b) recovering heat of the high-pressure gas stream via heat exchange with a heat sink, where a condensate forms, said condensate containing approximately 20-60 wt % water, present in the high-pressure gas stream, and high-pressure exhaust gas containing approximately 40-80 wt % water present in the high-pressure gas stream, remains uncondensed and temperature or pressure of the heat sink increases; and c) expansion of the high-pressure exhaust gas which is uncondensed at step (b), containing approximately 40-80 wt % water, present in the high-pressure gas stream, in order to recover energy of the high-pressure exhaust gas in form of work; and d) directing the heat sink, whose temperature and pressure increases at step (c), to another step of the method for heating or using outside the method. The invention also relates to a method of producing aromatic carboxylic acids with energy recovery and a device for recovering energy.

EFFECT: invention significantly lowers power consumption during production of aromatic carboxylic acids.

16 cl, 3 dwg

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

FIELD: chemistry.

SUBSTANCE: method involves the following steps: (a) separation of a carbonylation product to obtain a gaseous overhead fraction containing acetic acid, methanol, methyl iodide, water, methyl acetate and at least one permanganate reducing compound, including acetaldehyde and less volatile fractions of catalyst; (b) distillation of the gaseous overhead fraction to obtain purified acetic acid and a low-boiling gaseous overhead fraction containing methanol, methyl iodide, water, acetic acid, methyl acetate and at least one permanganate reducing compound, including acetaldehyde; (c) condensation of the low-boiling gaseous overhead fraction and its separation into a condensed heavy liquid fraction which contains methyl iodide and methyl acetate and a condensed light liquid fraction containing water, acetic acid and at least one permanganate reducing compound, including acetaldehyde; (d) distillation of the light liquid fraction in a separate distillation column to obtain a second gaseous overhead fraction containing methyl iodide and at least one permanganate reducing compound, including acetaldehyde, and residue containing a fraction of high-boiling liquid containing methyl acetate, water and acetic acid, where the second gaseous overhead fraction is rich in permanganate reducing compounds relative the light liquid fraction; (e) condensation of the second gaseous overhead fraction containing methyl iodide and at least one permanganate reducing compound, including acetaldehyde, and aqueous extraction of the condensed stream to obtain a stream of an aqueous solution containing permanganate reducing compounds, including acetaldehyde, and a raffinate containing methyl iodide.

EFFECT: selective extraction and reduced amount of permanganate reducing compounds.

20 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a carboxylic acid synthesis method. The invention specifically relates to a method for synthesis of carboxylic acids through oxidation of a hydrocarbon with oxygen or an oxygen-containing gas, and more specifically to oxidation of cyclohexane to adipinic acid. According to the invention, the method involves a step for oxidising the hydrocarbon and at least one step for extracting the formed dicarboxylic acids from the reaction medium and, in known cases, return unconverted hydrocarbon and oxidation by-products such as ketones and alcohols which may be formed to the reaction. The disclosed method also includes a step for conversion, separation or extraction of α,ω-hydroxycarboxylic compounds formed during oxidation. This step for conversion, separation or extraction of α,ω-hydroxycarboxylic compounds involves oxidation of medium containing the said compounds in order to convert them to dibasic acids.

EFFECT: design of an efficient method of obtaining carboxylic acids.

16 cl, 10 ex

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: invention relates to improved carbonylation methods for producing acetic acid, one of which involves: (a) carbonylation of methanol or reactive derivative thereof in the presence of water, a catalyst selected from rhodium catalysts, iridium catalysts and mixtures thereof, a promoter from methyl iodide to form a reaction mixture with acetic acid in a reactor; (b) separating the stream of the reaction mixture with acetic acid into a liquid recirculation stream and a first stream of the crude product which contains acetic acid; (c) feeding the first stream of crude product into a column for distillation of light fractions; (d) distillation of the stream of crude product to remove low-boiling components as the overhead product and form a first stream of the purified product in form of a side stream and a liquid residual stream, the liquid residual stream primarily consisting of acetic acid, where the first stream of purified product is fed into a dehydration column, after which the dried product is fed into a column for distillation of heavy fractions, and acetic acid is collected in form of an overhead product from the column for distillation of heavy fractions; (e) evaporating at least a portion of the liquid residual stream to obtain a second product stream; and (f) feeding the second product stream after condensation or compression thereof for further processing after merging with the first stream of purified product into said dehydration column. The invention also relates to an apparatus for producing acetic acid, comprising: (a) a reactor for carbonylation of methanol or reactive derivatives thereof in the presence of water, a catalyst selected from rhodium catalysts, iridium catalysts and mixtures thereof, and a promoter from methyl iodide to form a reaction mixture with acetic acid in the reactor; (b) a flash evaporation apparatus connected to the reactor and configured for inlet of the stream of the reaction mixture and separation thereof into (i) a liquid recirculating stream and (ii) a crude first product stream containing acetic acid; (c) a column for distillation of light fractions, which is connected to the flash evaporation apparatus which is configured for separation of low-boiling components in form of an overhead product from the first product stream and formation of a first stream of purified product in form of a side stream, and a liquid residual stream; (d) a dehydration column connected to the column for distillation of light fractions; (e) a column for distillation of heavy fractions connected to the dehydration column; and (f) an evaporation reservoir, also connected to the column for distillation of light fractions, for evaporation of at least a portion of the liquid residual stream and configured to feed a second product stream into the dehydration column; or a column for distillation of the liquid residual stream to form a stream of the purified product and meant for feeding it into the dehydration column or into the column for distillation of heavy fractions, where the column for distillation of the liquid residual stream is a stripping column. The apparatus and methods of producing acetic acid thus involve extraction of the product from the residue of light fractions in a stripping column and feeding the extracted acid for further processing in order to increase efficiency of the system.

EFFECT: reduced load on the column for distillation of light fractions; the load on the dehydration column can also be reduced in the embodiment, wherein further removal of water from the extracted acid is not necessary.

15 cl, 4 dwg, 2 tbl

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