Removal of permanganate-reducing compounds from continuous methanol carbonylation process

FIELD: explosives.

SUBSTANCE: method is described for reducing amount and/or removing permanganate-reducing compounds for methanol carbonylation process to produce acetic acid, where the method involves a stage for separating the said carbonylation product, resulting in a volatile fraction containing acetic acid, organic iodide, water and at least one permanganate-reducing compound, and a less volatile fraction; distillation of the said volatile fraction, resulting in a purified acetic acid product and a first overhead fraction containing organic iodide, water, acetic acid and at least one permanganate-reducing compound; distillation of at least part of the first overhead fraction in a first distillation apparatus to form a second overhead fraction rich in permanganate-reducing compound; addition of dimethyl ether to the second overhead fraction, extraction of the second overhead fraction with water to form a second overhead extraction stream and a water stream containing at least one permanganate-reducing compound and separation from the water stream, containing at least one permanganate-reducing compound; and returning at least the first part of the extracted second overhead fraction to the said distillation apparatus, method of producing acetic acid and method of separating a mixture obtained during carbonylation of methanol.

EFFECT: more efficient removal of permanganate-reducing compound from a system by returning part of the stream of purified product, reduced loss during waste removal.

34 cl, 2 dwg

 

The prior art INVENTIONS

1. The technical FIELD TO WHICH the INVENTION RELATES.

This invention relates to an improved method for removal of permanganate reducing (CEM) compounds and alkyl iodides formed at carbonyliron methanol in the presence of a metal of group VIII as a catalyst for carbonylation. More specifically, this invention relates to an improved method for reducing and/or removing predecessors CEM-compounds and alkyl iodides from the intermediate flow upon receipt of acetic acid carbonyliron.

2. The LEVEL of TECHNOLOGY

Currently, among the methods used for the synthesis of acetic acid, one of the most commercially used is a catalytic carbonylation of methanol with carbon monoxide, as shown in U.S. patent No. 3769329 entered in the register Paulik et al October 30, 1973. The carbonylation catalyst contains rhodium, or dissolved or dispersed in a liquid reaction medium or deposited on an inert solid Foundation, together with the halogen-containing promoter catalyst, for example methyl iodide. Rhodium can be introduced into the reaction system in any of many forms, and the exact structure of the rhodium fragment in the active complex catalyst is uncertain. Similarly, the structure of the halogen p is omotara is not critical. The patents describe a very large number of suitable promoters, most of which are organic iodides. Most often the test is held constant bubbling gaseous carbon monoxide through the liquid reaction medium in which is dissolved catalyst.

The improvement in the previous method carbonylation of the alcohol in the presence of a rhodium catalyst to obtain a carboxylic acid having one carbon atom more than the alcohol, as is first described in U.S. patent No. 5001259 entered in the register of March 19, 1991; 5026908 entered in the register on 25 June 1991; and 5144068 entered in the register of September 1, 1992; and in European patent EP 0161874B2, published July 1, 1992. As disclosed in these patents, acetic acid is produced from methanol in a reaction medium containing methyl acetate, methyl halide, especially methyl iodide, and the rhodium is present in a catalytically effective concentration. These patents the first to describe that the stability of the catalyst and the performance of the carbonylation reactor can be stored at unexpectedly high levels, even at low water concentrations, ie 4 weight percent or less in the reaction medium (despite the common industrial practice of saving approximately 14-15 percent by weight of water) introducing into the reaction environment, the place with a catalytically effective content of rhodium and at least limiting water concentration, a certain concentration of iodide ions in excess of iodide content, which is present as methyl iodide or other organic iodide. Iodide ion is present as a simple salt, preferably lithium iodide. The patents disclose that the concentration of methyl acetate and iodide salts are essential parameters in achieving speed carbonylation of methanol to obtain acetic acid, especially at low concentrations of water in the reactor. Through the use of relatively high concentrations of methyl acetate and iodide salts can provide a significant level of stability of the catalyst and the performance of the reactor, even when the liquid reaction medium contains water in a concentration of about 0.1 weight %, such a low that in General terms it can be defined simply as "the maximum concentration of water. Additionally, the reaction medium improves the stability of the rhodium catalyst, i.e. resistance to his deposition, especially during the stages of product selection. In these stages of distillation for separation obtained acetic acid tends to remove from the catalyst, the carbon monoxide, which is stored in the reaction vessel and is a ligand having a stabilizing effect on the rhodium. U.S. patent No. 5001259, 5026908 and 5144068 included in this invention by city the Finance.

It was found that, although the method of carbonylation with low content of water to produce acetic acid reduces the amount of such by-products as carbon dioxide, hydrogen, propionic acid, the content of other impurities usually present in trace quantities, is also increased, and as acetic acid, sometimes worse, when attempts are made to increase the rate of formation of improved catalysts or by changing the reaction conditions.

These trace impurities affect the quality of acetic acid, especially when returning to the process of the reaction. Impurities, which reduce the lifetime permanganate in the process of obtaining acetic acid, include carbonyl compounds, unsaturated carbonyl compounds. Used here, the phrase "carbonyl" also refers to compounds that contain aldehyde or ketone functional group, and these compounds may contain, or no unsaturation (see Catalysis of Organic reaction, 75, 369-380 (1998) for further discussion of impurities in the carbonyl process).

This invention relates to the reduction of quantities and/or removal of permanganate reducing compounds (CEM-compounds, such as acetaldehyde, acetone, methyl ethyl ketone, Butyraldehyde, CROTONALDEHYDE, 2-ethyl CROTONALDEHYDE and ITIL-Butyraldehyde and the like, and products of aldol condensation. The invention also leads to a reduction of the amounts of propionic acid.

Such carbonyl impurities described above, as acetaldehyde can react with the iodide promoter of the catalyst with the formation of higher alkyl iodides, such as ethyl iodide, propyl iodide, butyl iodide, pentyl iodide, hexyl iodide and the like. It is desirable to remove the alkyl iodides from the reaction product, as even a small content of these impurities in acetic acid tends to poison the catalyst used in obtaining vinyl acetate - product of the most widely produced from acetic acid. Thus, the present invention relates to destroy alkyl iodides, in particular, C2-12the alkyl iodide compounds. Therefore, since many impurities originate from acetaldehyde, the primary objective is to remove or decrease the content of acetaldehyde and alkylated in this way.

The conventional methods to remove impurities include processing the received acetic acid oxidants, ozone, water, activated carbon, amines and the like, and such processing may be accompanied, or not, by distillation of acetic acid. The most typical treatment includes a series of distillations of the final product. It is known, for example, from U.S. patent No. 5783731 that for deletion is of carbonyl impurities from organic streams applies processing such threads amine compound as hydroxylamine, which reacts with the carbonyl compounds with the formation of Asimov, followed by distillation to separate the purified organic product from oxomnik products. However, additional processing of the final product increases the cost of the process and the distillation of the treated acetic acid can lead to the formation of additional impurities.

Although it is possible to obtain acetic acid is relatively high purity acetic acid, obtained through the method of carbonylation with low content of water and the above-described cleaning, thanks to the presence of small amounts of residual impurities often retains some failure in respect of permanganate time. Because the adequacy of the permanganate time is an important commercial test that received acid must withstand for many applications, the presence of impurities, which reduce the permanganate time is undesirable. Furthermore, it is not economically or commercially feasible to remove small amounts of these impurities from acetic acid by distillation, because some of these impurities have a boiling point close to the boiling point of acetic acid.

Thus, it is important to identify economically viable ways to remove impurities in the carbonyl process without contamination of the end is the product or undesirable increase in cost. U.S. patent No. 5756836 included in this invention as a reference, for the first time describes a method for the production of acetic acid of high purity by bringing the concentration of acetaldehyde in the reaction solution below 1500 ppm was found that by maintaining the concentration of acetaldehyde is below this limit, it is possible to suppress the formation of impurities to such an extent that for acetic acid of high purity is only necessary to overtake the crude acetic acid.

European patent EP 0487284 B1, published April 12, 1995, for the first time describes that the carbonyl impurities which are present in acetic acid, are concentrated in the upper chase with the upper part of the column. According to this top zipper light fractions from the column is processed amine compound (such as hydroxylamine), which reacts with the carbonyl compounds with the formation of derivatives Akimov that can be removed from the remaining top product distillation, resulting in acetic acid with improved permanganate time.

European application EP 0687662A2 and U.S. Patent No. 5625095 included in this invention by citing describe how to obtain the acetic acid of high purity in which the concentration of acetaldehyde 400 ppm or less remain in the reactor by use of a single or megastep natoi distillation for removal of acetaldehyde. The streams proposed for processing for removal of acetaldehyde include a light fraction containing mainly water, acetic acid and methyl acetate, and a heavy fraction containing mainly methyl iodide, methyl acetate and acetic acid; flow of the upper ring-containing mainly methyl iodide and methyl acetate; or return flow, formed by connecting the light and heavy fractions. These links do not determine which of these threads has the greatest concentration of acetaldehyde.

EP 0687662A2 and U.S. Patent No. 5625095 also the first to describe the control of the reaction conditions to control the formation of acetaldehyde in the reactor. Although it is argued that the formation of such by-products as CROTONALDEHYDE, 2-atolkachova aldehyde and alkyl iodides is reduced by controlling the formation of acetaldehyde, also emphasizes that control the reaction conditions, as proposed, increases the formation of propionic acid, an unintended by-product.

Recently, as is usually found in U.S. patent No. 6143930 and 6339171 that can significantly reduce the undesirable impurities in acetic acid by carrying out multi-step cleaning of the upper ring of light fractions of the column. These patents for the first time describe the purification method, in which the upper shoulder straps lung fra the Nations distilled twice, in each case selected acetaldehyde top zipper and is returned to the reactor residue, enriched methyl iodide. Enriched with acetaldehyde the distillate is extracted with water to remove the main part of the acetaldehyde in the drain, leaving a much smaller concentration of acetaldehyde in the purified product, which is returned to the reactor. U.S. patent No. 6143930 and 6339171 included in this invention by citation.

Although the above methods have been successful for the removal of carbonyl impurities from the system carbonylation, in the main part of the control levels of acetaldehyde and problems with permanganate time in the final product acetic acid, further improvements, however, can be made. Thus, there remains a need for alternative methods to improve the efficiency of removal of acetaldehyde. This invention is one such alternative solution.

The INVENTION

First, the invention provides a method for acetic acid, which comprises the following stages:

(a) reacting methanol and carbon dioxide in a suitable reaction medium, which contains the catalyst and organic iodide;

(b) separation of the reaction products on the volatile fraction, which contains acetic acid, organic is the cue iodide and at least one permanganate-reducing connection (CEM connection) and less volatile fraction containing the catalyst and acetic acid;

(c) distillation of the volatile fraction, leading to a purified product and the first upper shoulder strap, which contains organic iodide, water, acetic acid and unreacted methanol;

(d) distilling at least a portion of the first upper shoulder strap for receiving the second upper shoulder strap, enriched CEM-connection;

(e) extracting the second upper shoulder strap with water and separating therefrom for discharge into the flow of an aqueous extract containing concentrated CEM connection; and

(f) distilling at least part of the extracted second upper shoulder straps together with part of the first upper shoulder strap. The remaining portion of the extracted second upper shoulder strap is preferably returned to the reactor.

Secondly, this invention is an improved method of separating a mixture containing water, acetic acid, methyl iodide, methyl acetate, methanol, at least one C2-12the alkyl iodide and at least one permanganate-reducing connection (CEM connection). The improved method comprises the following stages: (a) distillation of the mixture with the formation of the flow of the upper shoulder strap, enriched CEM connection; (b) extracting the water flow of the upper shoulder strap, enriched CEM connection and separation therefrom of the water flow, steriade what about the at least one CEM connection; and (c) distilling at least part of the extracted upper shoulder strap, enriched CEM connection together with the original mixture.

Thirdly, this invention is an improved method for reducing and/or removal of permanganate reducing compounds (CEM connections) and C2-12alkyl iodides formed at carbonyliron of methanol to acetic acid. In this improved method, the methanol carbanilide in the reaction medium containing the catalyst and an organic iodide; products of carbonylation reactions are divided into (1) the volatile fraction containing acetic acid, organic iodide, water, and at least one CEM connection, and (2) less volatile fraction containing the catalyst; volatile fraction is distilled, yielding the purified product and the first upper ring-containing organic iodide, water, acetic acid and CEM connection. The improvement includes the following stages: (a) a first distillation top of shoulder strap, leading to the flow of the second upper shoulder strap, enriched CEM connection; (b) extracting the water flow of the second upper shoulder strap and separating therefrom an aqueous stream containing CEM connection; and (c) distilling at least part of the extracted second upper shoulder strap together with the first upper shoulder strap.

In a particularly preferred variant is ntah implementation of the present invention, the second upper wrap (or top wrap enriched CEM connection) contains dimethyl ether in a quantity sufficient to reduce the solubility of methyl iodide in extracting the water flow.

BRIEF DESCRIPTION of DRAWINGS

Fig. 1 represents a prior method for removing carbonyl impurities from the intermediate flow carbonyl process for acetic acid by carbonylation reaction, as first shown in U.S. patent No. 6339171.

Fig. 2 represents the preferred implementation of the present invention.

Although the invention permits of various modifications and alternative forms, specific embodiments of, shown on the example of the drawings, will be described here in detail. However, it should be understood that the invention is not limited presents separate forms. Moreover, the invention is intended to encompass all modifications, equivalent substitutions and alternatives falling within the scope of this invention as defined by the attached claims.

ILLUSTRATED DESCRIPTION of embodiments

Illustrated embodiments of the present invention is described below. In the interest of clarity, not all features of actual variant of the implementation presented in this description. Of course, will be high on enano, when the development of any valid case for many decisions that are dependent on options for implementation, should be made to achieve specific goals of researchers, such as coordination with system and economic constraints, which will vary from one option run to the next. In addition, it will be appreciated that such efforts towards the development can be complex and time-consuming, but, nevertheless, performs routine experts in this field who use the advantage of this opening.

The purification method of the present invention is used in any process for the carbonylation of methanol (or other carbonyliron reagent, such as methyl acetate, methyl formate or dimethyl ether) to acetic acid in the presence of such a metal catalyst of group VIII as rhodium and iodide promoter. Especially common process is catalyzed by a rhodium carbonylation of methanol to acetic acid at a low concentration of water, as described in the examples in U.S. patent No. 5001259. It is generally assumed that the rhodium component of the catalyst system is present in the form coordination compounds of rhodium and halogen component, which is at least one of the ligands of such to the coordination compounds. In addition to the coordination of rhodium and halogen, it is assumed that the carbon monoxide is coordinated with rhodium. The rhodium component of the catalyst system may be provided by introducing into the reaction zone of rhodium in metallic form of rhodium salts such as oxides, acetates, iodides, etc. or other coordination compounds of rhodium and the like compounds.

Promoting the halogen component of the catalyst system consists of halogen compounds, including organic halide. Thus, there may be used alkyl-, aryl - substituted alkyl - or aryl halides. Preferably the halogen promoter is present in the form of alkylhalogenide, in which the alkyl radical corresponds to the alkyl radical to be added carbonyliron alcohol. Thus, in carbonyliron of methanol to acetic acid, the halogen promoter will contain methyl halide, more preferred methyl iodide.

Apply the liquid reaction medium may include any solvent compatible with the catalyst system, and may include pure alcohols or a mixture of the injected alcohol and/or desired carboxylic acid and/or esters of these two compounds. The preferred solvent and liquid reaction medium for the method for carbonylation at low water content is the ultimate carboxylic acid is the same. Thus, in carbonyliron of methanol to acetic acid is the preferred solvent is acetic acid.

Water contained in the reaction medium, but at concentrations significantly lower compared to previously believe is acceptable to achieve a sufficient reaction rate. It was previously revealed that catalyzed by rhodium carbonylation reactions proposed in this invention, the addition of water has a beneficial effect on its speed (U.S. Patent No. 3769329). Thus, most commercially suitable operations occur at a concentration of water of at least about 14 weight %. Thus, it is quite unexpected that the reaction rate, substantially equal to and greater speed of reaction obtained at such high levels of water concentration can be achieved when the concentration of the water is below 14 percent by weight, and even at about 0.1 weight %.

According to the present invention for a method of carbonyl most used for the production of acetic acid, the desired reaction rate is obtained even at a low concentration of water included in the reaction medium methyl acetate and an additional iodide ion, in addition to the iodide present as a promoter of the catalyst, such as methyl iodide or other organic iodide. Extension the iodide promoter is iodide is Oh salt, preferably the lithium iodide. It was found that at low concentration of water, methyl acetate and lithium iodide act as promoters speed, only if each of these components are present in relatively high concentrations, and that promotion is more strongly expressed when these components are present together (U.S. Patent No. 5001259). It is assumed that the concentration of lithium iodide used in the reaction environment preferred reaction system carbonylation is quite high compared to the small concentration as used in the prior art associated with the use of halide salts in the reaction systems of this type. The absolute concentration of the iodide ion is not a limitation for the application of the present invention.

The reaction carbonylation of methanol to acetic acid can be made by contacting the applied methanol, which is in a liquid state, gaseous carbon monoxide, propulsively through a liquid reaction medium containing acetic acid as a solvent, and rhodium catalyst, methyl iodide the promoter, methyl acetate and incremental soluble iodide salt, temperature and pressure, which are acceptable for product education carbonylation. It is generally considered that important what is the concentration of iodide ion in the catalytic system, and not the cation associated with the iodide, and that at a given molar concentration of iodide nature of the cation is not as significant as the effect of the concentration of iodide. Can be used iodide salt of any metal, or any iodide salt of any organic cation, or Quaternary cation such as a Quaternary amine, phosphine or inorganic cation, assuming that the salt is sufficiently soluble in the reaction medium to provide the desired level of iodide. If iodide is added as a salt of the metal, the preferred iodide salts of metals selected from group IA and group IIA of the periodic table, as suggested in "Handbook of Chemistry and Physics, published by CRC Press, Cleveland, Ohio, 1975-76 (56th edition). Particularly applicable are the iodides of alkali metals, preferably lithium iodide. In the way carbonylation at low water content, the most used in this invention, the extension iodide is in addition to and in addition to organic iodide to the promoter in the catalyst solution at concentrations of from about 2 to about 20 weight %, methyl acetate is present in concentrations from about 0.5 to about 30 weight %, and lithium iodide is present in concentrations of from about 5 to about 20 weight %. The rhodium catalyst is present in concentrations of from approximately 200 to approximately the nutrient 2000 parts per million (ppm).

The typical reaction temperature for carbonylation will be from 150 to 250°C, and the temperature range from about 180 to 220°C is the preferred range. The partial pressure of carbon monoxide in the reactor can vary widely, but typically it is from about 2 to about 30 atmospheres, and preferably from about 3 to about 10 atmospheres. Taking into account the partial pressure of by-products and the vapor pressure of the contained fluid total pressure in the reactor will range from about 15 to about 40 atmospheres.

Typical recovery system components of the reaction and acetic acid, which is used to promote the iodide catalyzed by rhodium carbonylation of methanol to acetic acid, is shown in figure 1 and includes a liquid-phase carbonylation reactor, the pulse device division and the column of light fractions of methyl iodide and acetic acid 14, which has a side diversion of acetic acid 17, which is followed by further purification. Reactor and a switching device division is not shown in Fig. 1. It is assumed that they are standard equipment, it is now well known for carbonylation processes. The carbonylation reactor is usually or stir capacitive reactor or reactor type bubble to the Onna in which the interaction of the liquid or suspension is maintained automatically at a constant level. In this reactor is continuously introduced fresh methanol, carbon monoxide, additional water to save at least limit the concentration of water in the reaction medium, returned to the catalyst solution from the base pulse devices division, the return phase of methyl iodide and methyl acetate and return phase aqueous acetic acid from the host decanter of light fractions of methyl iodide and acetic acid-separating column 14. Apply distillation systems, which ensure the return of the crude acetic acid and returning the catalyst solution, methyl iodide, and methyl acetate in the reactor. In a preferred method, the carbon monoxide is continuously introduced into the carbonylation reactor is slightly below the blades of the mixer used for mixing the contents. Connect gas completely dispersed in the reacting fluid mixing. The gaseous stream is blown clean out of the reactor vented to prevent the accumulation of gaseous by-products and to maintain the partial pressure of carbon monoxide at a given total pressure of the reactor. The temperature in the reactor is controlled and the carbon monoxide is supplied at a rate sufficient for the storage of the desired total pressure in the reactor.

Liquid product is removed from the carbonylation reactor at a rate sufficient to maintain a permanent level, and is introduced into the switching device division. In a switching device dividing the catalyst solution is given as a stream from the bottom (mainly acetic acid containing rhodium and iodide salt along with lesser quantities of methyl acetate, methyl iodide and water), and a vaporous stream of the upper shoulder strap impulse devices division contains mainly acetic acid with methyl iodide, methyl acetate and water. Dissolved gases leaving the reactor and enter into the pulsing device division, composed partly of carbon monoxide together with such gaseous by-products such as methane, hydrogen and carbon dioxide and leave the switching device division as part of the flow of the upper shoulder strap. Thread the top of the shoulder strap is directed into the flow of the volatile fraction or on the separating column 14 as stream 26.

As was first shown in the U.S. patents No. 6143930 and 6339171, there is a higher concentration, approximately threefold, CEM-compounds and in particular acetaldehyde, in the flow of light phase compared to the flow of heavy phase leaving the column 14. Thus, in accord with the present invention, the stream 28 containing CEM connection, is sent to prinimaya the decanter top of shoulder strap 16, where the light fraction stream 30 is directed to distillation column 18.

Generally speaking, this invention may be discussed as an improved method for distillation CEM-compounds, mainly aldehydes and alkyl iodides, of the vaporous stream of acetic acid. The vaporous stream is distilled and extracted to remove the CEM connections. Especially preferred method of removing aldehydes and alkyl iodides from the first vaporous stream of acetic acid and reduce the level of propionic acid in the resulting acetic acid includes the following stages:

a) condensing the first vaporous stream of acetic acid in the first trap condensation and two-phase separation with the formation of the first liquid product of the heavy phase and the first liquid product easy phase, in which the first mentioned liquid heavy phase contains more catalytic components than said first liquid product easy phase;

b) distilling the liquid product easy phase to the first distillation column with the formation of the second vaporous stream of acetic acid, which is enriched with aldehydes and alkyl-iodides in comparison with the first-mentioned stream of vaporous acetic acid;

c) condensing the second vapor stream into a second trap condensation with the formation of Deuteronomy is the fifth liquid-phase product;

d) distilling the second liquid-phase product in the second ferry column with the formation of the third vapor stream;

(e) condensing the third vapor stream and extracting the condensed water stream to remove therefrom residual acetaldehyde; and

f) returning at least part of the extracted third vapor stream to the second distillation column.

The previous version of the implementation, as first shown in U.S. patent No. 6339171 depicted in figure 1. Presented at the figure 1, the first stream of gaseous acetic acid (28) contains methyl iodide, methyl acetate, acetaldehyde and other carbonyl components. Then this stream is condensed and separated (capacity 16) for separating a heavy phase containing the major part of the catalytic component, which is returned to the reactor (not shown in figure 1), from the light phase (30)containing acetaldehyde, water, and acetic acid.

Any phase from the upper ring of light fractions may be further distilled to remove the CEM connections and mainly acetaldehyde component of this thread, although it is preferable to remove the CEM connection of the light phase (30), since it was found that the concentration of acetaldehyde in this phase to some extent more. In the embodiment shown and described is here the distillation is performed in two stages, but it will be appreciated that the distillation can also be carried out in a single column.

The light phase (30) is directed to the column 18, which serves for the formation of the second vapor phase (36), enriched with aldehydes and alkyl-iodides in comparison with the thread 28. Stream 36 is condensed (capacity 20) and dwuhfazno split with the formation of a second liquid product of the heavy phase and the second liquid product is easy phase. This second heavy liquid phase contains more catalytic component than the second liquid light phase, and then returned to the reactor. The second liquid light phase (40)containing acetaldehyde, methyl iodide, methanol and methyl acetate, is sent to the second distillation column (22), in which acetaldehyde is separated from the other components. It was found that this method of the present invention reduces the content and/or remove at least 50% of the alkyl iodide impurities detected in the stream of acetic acid. It was also found that acetaldehyde and its derivatives reduced the content and/or removed by at least 50%, more often at more than 60%. Consequently, it is possible to keep the concentration of propionic acid in the resulting acetic acid is lower than about 400 parts per million by weight, and preferably below 250 parts per million.

From ver the and the separation column 14 pairs are removed via stream 28, are condensed and sent to the tank 16. Vapors are cooled to a temperature sufficient to condense and separate the condensed substance in two phases: water and methyl iodide, methyl acetate, acetaldehyde and other carbonyl components. Part of the stream 28 contains non-condensable gases, such as carbon dioxide, hydrogen and the like, which may be separated by ventilation, shown as stream 29 in figure 1. From the makers of the decanter top of shoulder strap 16 extends the flow of heavy phase 28, not shown in figure 1. Usually this heavy phase is returned to the reactor, but the outlet stream, usually a small amount, for example 25 %by volume, preferably less than about 20 %by volume, heavy phase can also be sent to the carbonyl process processing, and the remainder is returned to the reactor or reaction system. This bypass flow of heavy phase can be processed separately or after combining with the light phase (stream 30) for further distillation and extraction of carbonyl impurities.

The light phase (stream 30) were sent to distillation column 18. Part of the flow 30 went back to the upper part of the column 14 as the return flow of condensate 34. The remainder of the stream 30 enters the column 18 about the center of the column as stream 32. Column 18 is used for concentration of the aldehyde components of stream 32 stream werhner the shoulder straps 36 by separation of water and acetic acid from lightweight components. The thread 32 is distilled in a first distillation column 18, which preferably contains approximately 40 plates, and the temperature here varies from about 283°F (139,4°C) in the cube to about 191°F (88,3°C) at the top of the column. Stream 38 exiting the bottom of column 18 contains approximately 70% water and 30% acetic acid. Stream 38 is processed, is usually cooled in a heat exchanger, and returns to the upper wrap-decanter 16 upper fractions of the column through the threads 46 and 48 and ultimately to the reactor (reaction system). It was found that the return part of the stream 38, indicated as stream 46, back through the decanter 16 increases the efficiency of the method of the present invention and allows greater part of the acetaldehyde present in the light phase (stream 32). It was found that the thread 36 is approximately seven times higher content of aldehyde when the thread 38 is returned so through the decanter 16. Thread 36 extending from the top of column 18 contains a CEM connection and in particular acetaldehyde, methyl iodide, methyl acetate, methanol and alkyl iodides. Then the stream 36 is sent to the receiver of the upper ring 20 after it is cooled to condense all present condensed gases.

With the receiver on top of the shoulder strap 20 extends stream 40 containing acetaldehyde, methyl iodide, methyl acetate and methanol. Part of the Otok 40 is returned to the column 18 as the return flow runoff 42. The remainder of the stream 40 enters into the second distillation column 22 is closer to the base of the pillar. Column 22 serves to highlight the main part of the acetaldehyde methyl iodide, methyl acetate and methanol in stream 40. In one embodiment, the implementation of the column 22 contains about 100 plates and operates at a temperature of from about 224°F (106,60°C) in a bottom part up to approximately 175°F (79,4°C) above. In an alternative preferred embodiment, the column 22 is structured nozzle in the area of the plates. Preferred structured packings with a working area of about 65 ft2/ft3preferably made of metal alloy, such 2205 or other similar material that is compatible with compositions treated in the column. During experimentation it was observed that the standard loading of the column, which is required for good separation is achieved easier with structured nozzle than with plates. Alternatively, it may be applied ceramic nozzle material. The residue from the column 22, the thread 44 extends from the base of the column and returned to the carbonylation process.

As first shown in U.S. patent No. 6339171, it was found that during the heating of the column 22 are formed polymers of acetaldehyde with high molecular weight. It is assumed that these polymers with high molecular the m weight (molecular weight of more than about 1000) are formed during the conversion of the light phase and are viscous and thixotropic. When the heat input to the system, they tend to cure and adhere to the walls of the column, where their removal is cumbersome. Being depolimerizovannogo they are only slightly soluble in organic or aqueous solvents and can be removed only by mechanical methods. Thus, the required inhibitor, preferably in the column 22, to reduce the formation of these impurities, i.e. metaldehyde and paraldehyde is recommended and polymers of acetaldehyde high molecular weight. Inhibitors usually consist of C1-10alcohols, preferably methanol; water; acetic acid and the like used individually or in combination of one inhibitor with one or more other inhibitor. Stream 46, which is part of the rest of the columns 18 and bypass flow for the stream 38 contains water and acetic acid and, thus, can act as a inhibitor. As shown in figure 1, the thread 46 is cleaved with the formation of the threads 48 and 50. Stream 50 is added to the column 22 for inhibiting the formation of impurities metaldehyde, paraldehyde is recommended and polymers of higher molecular weight. As the remainder of the second column 22 is returned to the reactor, any added inhibitors should be compatible with the chemistry of the reaction. It was found that a small content of water, methanol, acetic acid or their combinations are not what I obstacle for chemical reactions and practically inhibit the formation of polymers of acetaldehyde. Preferably the thread 50 is also used as the inhibitor, because this thread does not change the balance of water in the reactor. Although water is not an inhibitor, other important advantages, explained below, were obtained by adding water to the column 22.

Stream 52 containing CEM-link, goes to the top of the column 22. Stream 52 were directed to a device for condensing and then into the receiver top of the shoulder strap 24. After condensation of all non-condensable gases are ventilated from receiver 24; and condensed matter leave the receiver 24 as stream 54. Stream 56, the discharge flow stream 54, was used as the reverse flow of runoff to the column 22. Stream 44 containing methyl iodide, methanol, methyl acetate, methanol and water comes out from the base of the column 22. This stream is combined with the stream 66, which will be described below, and is sent to the reactor.

For the mechanism of extraction is important that the flow of the upper shoulder strap with columns 22 remained cold, usually at a temperature of about 13°C. This stream can be obtained at a temperature of about 13°C or stored at this temperature the usual methods known in the art, or any device commonly used in the industry.

After exiting the receiver 24 stream 58 is preferably passes through the condensation unit/chiller (hereinafter referred to as stream 62) in the extractor 27 for selection and who the treatment of small quantities of methyl iodide from the aqueous stream CEM connection. In the extractor 27 CEM-compounds and alkyl iodides extracted with water, preferably water from an external thread, to keep the balance of water in the reaction system. As a result of this extraction, methyl iodide is separated from the water CEM connection and faction alkyl iodide. In the preferred embodiment, is applied to the mixer-settler with respect to water-water supply of about 2.

The flow of aqueous extract of 64 leaves the extractor from its top. This enriched CEM connection, and particularly enriched acetaldehyde aqueous phase is sent to waste treatment. Also from the extractor enters the stream of purified product 66 containing methyl iodide, typically returned to the reaction system and ultimately into the reactor.

The authors of the present invention have found that the return of at least part of the flow of the pure product 66 in the distillation column 22 improves the removal efficiency of the aldehyde from the system as a whole. This can be achieved by returning at least part of the stream 66 at any point between the thread 32 (supply on the column 18) and extractor 27. In the embodiment shown in figure 2, the portion of the stream 66 is separated as stream 68 and enters the column 22 or by mixing with a flow of 40 inlet to the column or the introduction thread 68 directly to the column at a different point.

In one embodiment, done by the means of this invention the entire flow 66 may be returned to the column 22. It was found, however, that return at least part of the stream 66 in the reaction system is preferable to return the entire flow at the column 22. When the authors of this invention have begun testing of the present invention, it was found that the pressure in the column 22 is increased considerably compared to normal, showing the accumulation of volatile component in the system, which was not removed during the extraction. The authors of this invention have found that there are a number of chemical reactions taking place in the column 22, including the hydrolysis of methyl acetate and methyl iodide to methanol followed by the formation of dimethyl ether (DME). DME was identified as the volatile component, which causes an increase in pressure in the column. When the entire flow of the pure product 66 of the extractor 27 is returned to the column 22, DME, formed in the column is not deleted from the system. On the other hand, however, this result may be achieved by returning part of the stream 66 directly or indirectly to the system of the reactor. For example, the stream 66 can be returned into the tank 16 where it is combined with the heavy phase, which is returned to the reactor as described above. Because DME may be subjected to carbonyliron in the reactor for the production of acetic acid, the return of a certain amount of DME-soderzhimogo stream 66 directly or incidental is Anno in the reactor effectively prevents the accumulation of DME in the system of removal of acetaldehyde.

At the same time, however, the authors of the present invention have also discovered an unexpected benefit of small quantities of dimethyl ether in the system of removal of acetaldehyde. On the other hand, DME especially reduces the solubility of methyl iodide in water. Thus, the presence of a supply of DME in the extractor 27 reduces the content extracted methyl iodide in the stream 64 and losses at disposal. For example, the authors of this invention have found that the concentration of methyl iodide in stream 64 decreases from about 1.8%, when DME is not present, up to about 0.5%, when DME is present. As explained above, because methyl iodide is particularly expensive component of the reaction system, it is highly desirable to minimize the amount of methyl iodide is removed from the process as waste, whereby decreases the amount of fresh methyl iodide, which must be added to the reactor. Therefore, another aspect of the present invention includes a step of injection box incremental flow of DME in the extractor 27, such as stream 62, to reduce the loss of methyl iodide in the flow of aqueous extract of 64. Otherwise, you may receive additional DME adding additional water to the column 22 or in the underwater stream 40, or in the return flow runoff 56.

While the invention has been described with reference to preferred the sustained fashion options implementation obvious modifications and changes can be made by specialists. In particular, although the present invention is generally devoted to the utilization of light fractions from the column 14, any thread in the carbonylation process, having a high concentration CEM-compounds and alkylation, can be processed in accordance with the present invention. Thus, it is claimed that the invention includes all such modifications and changes in full, and that they fall within the scope of the attached claims of the invention or its equivalents.

1. Method for reducing and/or removing permanganatometricly compounds (CEM connections) and C2-12alkylidene compounds produced during carbonyliron carbonyliron reactant selected from methanol, methyl acetate, methylformate, dimethyl ether or mixtures thereof to obtain a product of the carbonyl containing acetic acid, organic iodide, water, and at least one permanganatometricly connection, including the stage,
separation of the above-mentioned carbonylation product, leading to containing acetic acid, organic iodide, water and at least one CEM connection volatile fraction and a less volatile fraction;
distillation mentioned the volatile fraction, leading to a purified product of acetic acid and the ground is the top of the shoulder strap, containing organic iodide, water, acetic acid, and at least one CEM-connection;
distillation, at least part of the first upper shoulder strap in the distillation apparatus with the formation of the second upper shoulder strap, enriched CEM-connection;
adding dimethyl ether to the second upper shoulder strap, extraction of the second upper shoulder strap water with the formation of the second upper extracted stream and a water stream containing at least one of the mentioned CEM connection and the separation from the aqueous stream containing at least one of the mentioned CEM connection; and
return at least the first part of the extracted second upper shoulder strap in said distillation apparatus.

2. The method according to claim 1, which further contains an introduction of at least the second part of the extracted second upper shoulder strap directly or indirectly in the reaction mixture.

3. The method according to claim 2, in which the aforementioned organic iodide contains methyliodide, and where mentioned second upper wrap contains dimethyl ether in amounts effective to reduce the solubility of methyliodide in the above-mentioned aqueous stream.

4. The method according to claim 2, further containing a formation of dimethyl ether in the above-mentioned distillation apparatus.

5. The method according to claim 4, further comprising a stage of addition of water is mentioned distillation apparatus, whereby dimethyl ether is formed in the distillation apparatus.

6. The method according to claim 1, in which returned the first portion of the extracted second upper shoulder strap is sent to distillation unit in conjunction with a part of the first upper shoulder strap.

7. The method according to claim 1, in which returned the first portion of the extracted second upper shoulder strap is sent to distillation apparatus separately from the part of the first upper shoulder strap.

8. The method according to claim 1, further comprising a stage of adding dimethyl ether, at least one stream selected from
mentioned the volatile fraction, referred to the first upper ring-mentioned second upper shoulder strap, the return flow of runoff obtained from the distillation of the specified volatile fraction, and return flow runoff mentioned stills.

9. The method according to claim 1, wherein at least one of the mentioned CEM-compound contains acetaldehyde.

10. The method according to claim 9, in which a sufficient amount of the above-mentioned acetaldehyde is removed from the aforementioned volatile fraction for maintaining the concentration less than 400 parts per million by weight of propionic acid in the above purified product acetic acid.

11. The method according to claim 9, in which a sufficient amount of the above-mentioned acetaldehyde is removed from the aforementioned volatile fraction to preserve concentrate the radio less than 250 parts per million by weight of propionic acid in the above purified product acetic acid.

12. The method according to claim 1, in which stage of the distillation mentioned first upper shoulder strap contains a number of successive stages of distillation, in which the first part of these extracted second upper shoulder strap is returned to the thread associated with the second or subsequent stages mentioned distillation.

13. The method for obtaining acetic acid, comprising the stage
(a) carbonylation of at least one reactant selected from methanol, methyl acetate, methylformate, dimethyl ether in a reactor containing a suitable reaction medium containing an organic iodide, water and at least one permanganatometricly connection;
(b) separation of the products mentioned carbonylation on the volatile fraction containing acetic acid, organic iodide, water and at least one permanganatometricly connection (CEM connection), and less volatile fraction;
(c) distilling mentioned the volatile fraction with the formation of the pure product of acetic acid and the first upper ring-containing organic iodide, water, acetic acid, and at least one mentioned CEM-connection;
(d) distilling at least a portion of the first upper shoulder strap for receiving the second upper shoulder strap, enriched CEM-connection;
(e) adding dimethyl ether in the second the top zipper and
(f) extracting the second upper shoulder strap water from getting extracted second top stream and a water stream containing at least one CEM connection, and remove it and drain the water extract containing at least one CEM-connection, in which at least the first portion of the extracted second upper shoulder strap back and distilled at stage (d) together with the first upper shoulder strap.

14. The method according to item 13, in which the aforementioned organic iodide contains methyliodide and second upper wrap contains dimethyl ether in amounts effective to reduce the solubility of methyliodide in the above-mentioned aqueous stream.

15. The method according to item 13, further comprising the stage of adding dimethyl ether, at least one stream selected from the aforementioned volatile fraction, referred to the first upper ring-mentioned second upper shoulder strap, the return flow of runoff associated with the distillation of the volatile fraction and flow associated with the distillation of the first upper shoulder strap.

16. The method according to item 13, further comprising returning at least a second part of the extracted second upper shoulder strap directly or indirectly in the reactor.

17. The method according to item 16, further comprising the formation of dimethyl ether during the distillation of the first verhnesadovoe and reacting at least part of dimethyl ether with carbon monoxide in the reactor.

18. The method according to 17, further comprising the stage of water injection box in the upper shoulder or in the first part of the extracted second upper shoulder strap, promoting the formation of dimethyl ether in the distillation of part of the first upper shoulder strap.

19. The method according to item 13, in which stage distillation at least part of the first upper shoulder strap contains a number of successive stages of distillation, in which the first part of these extracted second upper shoulder strap is returned to the thread associated with the second or subsequent stages mentioned distillation.

20. The method according to item 13, in which at least one of the mentioned CEM-compound contains acetaldehyde.

21. The method according to claim 20, in which a sufficient amount of the above-mentioned acetaldehyde is removed from the aforementioned volatile fraction to maintain the concentration of propionic acid in the above purified product acetic acid is less than 400 parts per million by weight.

22. The method according to claim 20, in which a sufficient amount of the above-mentioned acetaldehyde is removed from the aforementioned volatile fraction to maintain the concentration of propionic acid in the above purified product acetic acid is less than 250 parts per million by weight.

23. Method for the separation of mixtures formed during carbonyliron methanol, water-containing acetic acid is, methyliodide, methyl acetate, methanol, at least one €2-12alkylated and at least one permanganatometricly connection (CEM-connection), which includes
(a) distillation of the mixture, leading to enriched CEM connection thread of the upper shoulder strap, which contains methyliodide, water and at least one mentioned CEM-connection;
(b) adding dimethyl ether enriched CEM connection thread of the upper ring;
(c) extracting the water flow of the upper shoulder strap, enriched CEM connection, and the separation from it of the water stream containing at least one of the mentioned CEM connection; and
(d) distilling at least the first part of the extracted upper shoulder strap, enriched CEM connection, together with the original mixture.

24. The method according to item 23, in which the stage of distillation of the mixture contains a number of successive stages of distillation, in which the first part of these extracted the top of the shoulder strap, enriched CEM connection is returned to the thread associated with the second or subsequent stages mentioned distillation.

25. The method according to item 23, which includes the stage of adding dimethyl ether to at least one stream selected from
mentioned mixture, referred to the top of the shoulder strap, enriched CEM connection, and flows associated with these negotiations is coy.

26. The method according to item 23, in which the aforementioned second upper wrap contains dimethyl ether in amounts effective to reduce the solubility of methyliodide in the above-mentioned aqueous stream.

27. The method according to item 23, further comprising the stage of preparation of the aforementioned mixture by separation of the liquid composition on the light and heavy fractions where the above-mentioned liquid composition comprises water, acetic acid, methyliodide, methyl acetate, methanol, at least one With2-12alkylated and at least one mentioned CEM-connection, in which the light fraction contains the above-mentioned mixture, and the heavy fraction contains methyliodide.

28. The method according to item 27, further comprising the stage of carrying out phase separation of the liquid-vapor at the outlet of the reactor carbonylation of methanol with the formation of a vapor phase and a liquid phase; distilling the vapor phase with the formation of the first upper shoulder strap and a liquid product; liquefying at least part of the first top of shoulder strap, leading to the aforementioned liquid composition.

29. The method according to p, in which at least one of the mentioned CEM-compound contains acetaldehyde.

30. The method according to clause 29, in which a sufficient amount of the above-mentioned acetaldehyde is removed from the aforementioned volatile fraction to maintain the concentration of propionic acid in the above purified product acetic acid is less than h is m 400 parts per million by weight.

31. The method according to clause 29, in which a sufficient amount of the above-mentioned acetaldehyde is removed from the aforementioned volatile fraction to maintain the concentration of propionic acid in the above purified product acetic acid is less than 250 parts per million by weight.

32. The method according to p, further containing a return of at least part of the extracted top enriched CEM connection, shoulder strap, directly or indirectly, in the carbonylation reactor.

33. The method according to p, further containing a formation of dimethyl ether in the process of distillation mentioned mixture and reacting at least part of dimethyl ether with carbon monoxide in the reactor.

34. The method according to p, further comprising a stage of addition of water, promoting the formation of dimethyl ether in the course of the distillation, to the mixture or to the stream associated with the distillation mixture, or in the first part of the extracted upper shoulder strap, enriched CEM connection.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of reducing and/or removing reducing permanganate compounds (RPC), carboxylic acids C3-8 and C2-12 of alkyl iodide compounds, formed during carbonylation of a carbonylation-capable reagent, chosen from a group consisting of methanol, methylacetate, methyl formate, dimethyl ether and their mixture, into commercial-grade acetic acid, in which products of the said carbonylation include a volatile phase, which is distilled thereby obtaining purified commercial-grade acetic acid and the first distillate, containing methyl iodide, water and at least one reducing permanganate compound, where improvement includes stages: (a) separation of the obtained first distillate into a light and a heavy phase, with subsequent distillation of at least part of the light phase for obtaining a second distillate, containing methyl iodide, dimethyl ether and at least said one reducing permanganate compound, which is taken to the next distillation stage, where a stream is formed as distillate, containing reducing permanganate compound; (b) addition of dimethyl ether into supply of said stream containing reducing permanganate compound, and extraction of this stream with water to form the first raffinate and first aqueous extraction stream, containing at least said one reducing permanganate compound; and (c) extraction of the first raffinate with water to form the second raffinate and second aqueous extraction stream, containing at least said one reducing permanganate compound. Invention also relates to a method of separating a mixture, containing water, acetic acid, methyl iodide, methyl acetate, methanol and at least one reducing permanganate compound (RPC), obtained by separating the liquid-vapour phase of the output stream of the methaol carbonylation reactor to form a vapour phase and a liquid phase, distillation of the vapour phase to form a liquid product which contains acetic acid, and first distillate, condensation of at least part of the first distillate thereby obtaining a liquid composition which contains methyl acetate, methyl iodide, water, methanol and at least one reducing permanganate compound (RPC), separation of the obtained liquid composition into a light and a heavy phase, which includes methyl iodide, where the light phase is the said mixture, where the said method involves stages: (a) distillation of the mixture to obtain a second distillate which contains at least one reducing permanganate compound (RPC), which is taken for the next distillation stage, where a stream is formed as distillate, containing reducing permanganate compound and dimethyl ether; and (b) extraction of concentrated reducing permanganate compound with water, where stage (b) includes at least two consecutive extraction stages, where each extraction stage involves bringing concentrated reducing permanganate compound into contact with water and separation of the aqueous stream, containing at least said one reducing permanganate compound, where dimethyl ether is added to the said distillate stream concentrated with reducing permanganate compound before extraction of the concentrated reducing permanganate compound with water.

EFFECT: process is described for removing reducing permanganate compounds from a stream from carbonylation of methanol.

28 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: method includes carbonylation of the alcohol and/or of its reactive derivative with carbon monooxide in liquid reaction mixture carried out in carbonylation reactor. The said liquid reaction mixture contains the said alcohol and/or its reactive derivative, carbonylation catalyst, alkyl halide cocatalyst whereat the said catalyst includes at least one metal selected from rhodium or iridium coordinated with polydentate ligand whereat the said polydentate ligand has the bite angle at least 145° or forms the "hard" Rh or Ir metal-ligand complex; the said polydentate ligand includes at least two coordination groups; at least two of them independently contain P, N, As or Sb as coordination atoms. The hydrogen/carbon monooxide mole ratio is supported in the range at least 1:100 and/or carbon monooxide directed to carbonylation reactor contains at least 1 mole % of hydrogen; catalyst flexibility range is less 40°. The method is tolerable to hydrogen presence i.e. liquid side-products are formed in small amounts or are not formed at all.

EFFECT: improvement of the method of carboxylic acid and its ester obtaining.

49 cl, 3 tbl, 13 ex

FIELD: chemistry.

SUBSTANCE: proposed method involves the following stages: (a) reaction of carbon monoxide with at least one reagent chosen from a group, consisting of methanol, methyl acetate, methyl formate and dimethyl ether and their mixture in a reaction medium, containing water, methyl iodide and catalyst for obtaining the reaction product, containing acetic acid; (b) gas-liquid separation of the said reaction product to obtain a volatile phase, containing acetic acid, water and methyl iodide and a less volatile phase, containing the said catalyst; (c) distillation of the above mentioned volatile phase to obtain a purified product of acetic acid and a first overhead fraction, containing water, methylacetate and methyl iodide; (d) phase separation of the above mentioned first overhead fraction to obtain the first liquid phase, containing water, and second liquid phase, containing methyl iodide and methyl acetate; and (e) feeding dimethyl ether directly or indirectly into a decantation tank of light fractions for phase separation of the said first overhead fraction in a quantity, sufficient for increasing separation of the first overhead fraction to form the first and second liquid phases.

EFFECT: improvement of the method of producing acetic acid.

8 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: proposed is a method of oxidising alkane from C2 to C4, obtaining the corresponding alkene and carboxylic acid and/or oxidising alkene from C2 to C4, obtaining the corresponding carboxylic acid. The method involves addition into the reaction zone of the above mentioned alkane and/or alkene, containing molecular oxygen gas, carbon monoxide and optionally water, in the presence of a catalyst, effective for oxidising the alkane to the corresponding alkene and carboxylic acid and/or effective for oxidising the alkene to the corresponding carboxylic acid at temperature between 100 and 400 °C. Concentration of carbon monoxide is kept between 1 and 20% of the total volume of the initial material added to the oxidation reaction zone. The method can optionally involve further reaction in a second reaction zone.

EFFECT: new oxidation method for producing carboxylic acids and alkenes.

30 cl, 3 ex, 1 tbl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to improved method of producing methanol, acetic acid and optionally vinyl acetate, which includes integrated stages: separation of hydrocarbons source into first and second hydrocarbons flows; vapour reforming of first hydrocarbons flow with vapour in order to obtain subjected to reforming flow; autothermal reforming of mixture of subjected to reforming flow and second hydrocarbons flow with oxygen and carbon dioxide in order to obtain synthesis-gas flow; separation of smaller part of synthesis-gas flow into flow with higher carbon dioxide content, flow with higher hydrogen content and flow with higher content of carbon oxide; recirculation of flow with higher carbon dioxide content to autothermal reforming; compression of remaining part of synthesis-gas flow, CO2 flow, not necessarily from associated process, and at least part of flow with higher hydrogen content for supplying feeding flow to circuit of methanol synthesis in order to obtain methanol product, whose stoichiometric coefficient is determined as [(H2-CO2)/(CO+CO2)], and stoichiometric coefficient of feeding flow constitutes from 2.0 to 2.1; acetic acid synthesis from at least part pf methanol product and flow with higher content of carbon oxide, and optionally synthesis of vinyl acetate from at least part of synthesised acetic acid.

EFFECT: elaboration of improved method of producing methanol, acetic acid, characterised by highly economical indices and low intensity of CO2 emission.

23 cl, 2 ex, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention concerns improved method of obtaining carboxylic acid and/or complex alcohol ether and carboxylic acid, involving carbonylation of C1-C8 aliphatic alcohol and/or its reactive derivative by carbon monoxide in liquid reaction mix in carbonylation reactor. Liquid reaction mix includes indicated alcohol and/or its reactive derivative, carbonylation catalyst, alkylhalide co-catalyst and optionally water in limited concentration, the catalyst including cobalt, rhodium or iridium coordinated with tridentate ligand, or their mix. Also invention concerns application of carbolylation catalyst including cobalt, rhodium or iridium coordinated with tridentate ligand, or their mix, in carbonylation method of obtaining carboxylic acid and/or complex alcohol ether and carboxylic acid.

EFFECT: enhanced carbonylation speed and selectivity.

36 cl, 6 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention claims method of preparation of catalytic composition applied onto a carrier and acceptable for ethane and/or ethylene oxidation to acetic acid, where catalytic composition applied onto carrier includes catalyst of one or more metal components, on a carrier with aluminium alpha-oxide. Method involves the following stages: (a) preparation of suspension of one or more metal components and aluminium alpha-oxide carrier or carrier precedent particles, (b) dispersion drying of suspension, and optionally (c) calcination of dispersion-dried suspension to obtain catalytic composition applied onto carrier. Invention also claims catalytic composition applied onto carrier and obtained by the claimed method, and method of selective ethane and/or ethylene oxidation to acetic acid using the catalytic composition applied onto carrier.

EFFECT: high selectivity of target products and reduced COX generation.

44 cl, 2 tbl, 1 dwg, 3 ex

FIELD: chemistry.

SUBSTANCE: reaction of alkene with molecular oxygen is carried out in reactor with pseudoliquefied layer in presence of catalytically active pseudoliquefied layer of solid particles, which lies in the following: gas, containing molecular oxygen, concentration of oxygen in which exceeds its concentration in air, is introduced into pseudoliquefied layer simultaneously supporting turbulent mode in pseudoliquefied layer. Invention also relates to method of obtaining vinylacetate by reaction of ethylene and acetic acid with molecular oxygen in reactor with pseudoliquefied layer in presence of catalytically active pseudoliquefied layer of solid particles, which have diameter in range from 20 to 300 mcm, distribution according to particle diameter constitutes at least 20 mcm; at to method of carrying out reaction of molecular oxygen with ethane, ethylene or their mixture obtaining acetic acid and optionally ethylene in reactor with pseudoliquefied layer in presence of catalytically active pseudoliquefied layer of solid particles.

EFFECT: elaboration of safer method of carrying out reaction.

45 cl, 2 tbl, 3 ex,4 dwg

FIELD: chemistry.

SUBSTANCE: improved is method of obtaining acetic acid by means of carbonilation of methanol and/or its reaction-able derivative with carbon monoxide in carbonilation reaction zone, which contains liquid reaction medium, including iridium carbonilation catalyst, methyliodide co-catalyst, amount of water within range from 0.1 to 20 wt %, acetic acid, methylacetate, at least one promoter - ruthenium, and stabilising compound, selected from group, which consists of alkali metal iodides, alkali-earth metal iodides, metal complexes, able to generate ions I-, salts, able to generate I-, and mixtures of two or more such compounds, molar ratio of promoter to iridium being more than 2 up to 15:1, and molar ratio of stabilising compound to iridium is within range (from more than 0 to 5):1, and where method includes additional stages: a) from said carbonilation reaction zone liquid reaction medium with dissolved and/or carried along carbon monoxide and other gases is drained; b) said drained liquid reaction medium is not obligatory passed through one or several additional reaction zones in order to convert at least part of dissolved and/or carried along carbon monoxide; c) said liquid reaction medium from stage (a) and stage (b) is passed in one or several stages of fast evaporation, in order to form (i) vapour fraction, including condensing components and waste low pressure gas, condensing components contain obtained acetic acid and waste low pressure gas, which contains carbon monoxide and other gases, dissolved and/or carried along with drained liquid reaction medium, and (ii) liquid fraction, including iridium carbonilation catalyst, promoter and acetic acid as solvent; d) from waste low pressure gas condensing components are separated; and e) liquid fraction from stage of fast evaporation is recirculated into carbonilation reactor.

EFFECT: method allows to prevent or reduce loss of catalyst and promoter.

14 cl, 7 tbl, 2 dwg, 32 ex

FIELD: chemistry.

SUBSTANCE: catalytic system for obtaining acetic acid includes iridium carbonilation catalyst, methyliodide co-catalyst, non-obligatory, at least one of the following elements: ruthenium, osmium, rhenium, zinc, gallium, tungsten, cadmium, mercury and indium, ant, at least, one promoter - non-halogenohydrogen acid. Non-halogenohydrogen acid can represent oxo-acid, superacid and/or hateropolyacid. Method of obtaining acetic acid by reaction of carbon monoxide with methanol and/or its reaction-able derivative in liquid reaction composition, which includes methylacetate, water in limited concentration, acetic acid and said catalytic system, is described. Application of catalytic system for obtaining acetic acid is described.

EFFECT: increasing rate of carbonilation.

27 cl, 5 tbl, 20 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of reducing and/or removing reducing permanganate compounds (RPC), carboxylic acids C3-8 and C2-12 of alkyl iodide compounds, formed during carbonylation of a carbonylation-capable reagent, chosen from a group consisting of methanol, methylacetate, methyl formate, dimethyl ether and their mixture, into commercial-grade acetic acid, in which products of the said carbonylation include a volatile phase, which is distilled thereby obtaining purified commercial-grade acetic acid and the first distillate, containing methyl iodide, water and at least one reducing permanganate compound, where improvement includes stages: (a) separation of the obtained first distillate into a light and a heavy phase, with subsequent distillation of at least part of the light phase for obtaining a second distillate, containing methyl iodide, dimethyl ether and at least said one reducing permanganate compound, which is taken to the next distillation stage, where a stream is formed as distillate, containing reducing permanganate compound; (b) addition of dimethyl ether into supply of said stream containing reducing permanganate compound, and extraction of this stream with water to form the first raffinate and first aqueous extraction stream, containing at least said one reducing permanganate compound; and (c) extraction of the first raffinate with water to form the second raffinate and second aqueous extraction stream, containing at least said one reducing permanganate compound. Invention also relates to a method of separating a mixture, containing water, acetic acid, methyl iodide, methyl acetate, methanol and at least one reducing permanganate compound (RPC), obtained by separating the liquid-vapour phase of the output stream of the methaol carbonylation reactor to form a vapour phase and a liquid phase, distillation of the vapour phase to form a liquid product which contains acetic acid, and first distillate, condensation of at least part of the first distillate thereby obtaining a liquid composition which contains methyl acetate, methyl iodide, water, methanol and at least one reducing permanganate compound (RPC), separation of the obtained liquid composition into a light and a heavy phase, which includes methyl iodide, where the light phase is the said mixture, where the said method involves stages: (a) distillation of the mixture to obtain a second distillate which contains at least one reducing permanganate compound (RPC), which is taken for the next distillation stage, where a stream is formed as distillate, containing reducing permanganate compound and dimethyl ether; and (b) extraction of concentrated reducing permanganate compound with water, where stage (b) includes at least two consecutive extraction stages, where each extraction stage involves bringing concentrated reducing permanganate compound into contact with water and separation of the aqueous stream, containing at least said one reducing permanganate compound, where dimethyl ether is added to the said distillate stream concentrated with reducing permanganate compound before extraction of the concentrated reducing permanganate compound with water.

EFFECT: process is described for removing reducing permanganate compounds from a stream from carbonylation of methanol.

28 cl, 2 dwg

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: present invention pertains to extraction of a metallic catalyst from a mother solution, obtained during synthesis of carbonic acid, usually terephthalic acid. In the first version, the method of separating metallic catalyst from a stream of mother solution involves the following stages: (a) evaporation of the mother solution, containing carbonic acid, the metallic catalyst, impurities, water and a solvent, in the zone of the first evaporator, obtaining a vapour, containing water and solvent, and concentrated mother solution; (b) evaporation of the concentrated mother solution in the zone of the second evaporator, where evaporation in the zone of the second evaporator is carried out at 150-220°C temperature, forming a stream rich in solvent and a stream of super-concentrated mother solution in molten dispersion state, where a total of 95-99 wt % of solvent and water is removed from the mother solution during evaporation stages (a) and (b); (c) mixing the water-solvent solution in the mixing zone, with super-concentrated mother solution, forming an aqueous mixture; (d) separation of organic impurities in the aqueous mixture in the separation zone of solid substance/liquid phase, forming a pure aqueous mixture; (e) addition of extraction solvent to the aqueous mixture or pure aqueous mixture in the extraction zone, forming an extract or rafinate, containing the metallic catalyst; and (f) separation of the extract and the solvent rich stream in the separation zone, forming a stream of organic impurities with high boiling point and a stream of extraction solvent. The invention has three versions.

EFFECT: extraction of expensive metallic catalyst in active form, suitable for repeated use, and acetic acid, contained in the mother solution with removal of most impurities present in the extracted stream.

20 cl, 1 tbl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to the removal of the metallic catalyst from stock solution, obtained during the synthesis of carboxylic acids, normally terephthalic acid. Method of removing the metallic catalyst from the stream of stock solution containing carboxyl acid includes the following stages: (a) graduating the stock solution, which contains the carboxyl acid, metallic catalyst, impurities, water and solvent, in the zone of the first evaporator obtaining a stream of water vapour and a stream of concentrated stock solution; (b) evaporating of the specified stream of concentrated stock solution to the zone of the second evaporator forming a stream rich in the solvent and a stream of super-concentrated stock solution; (c) removing organic impurities from super-concentrated stock solution with the help of water-solvent solution in the zone of the separating phase of solid substance/liquid forming a stream of water and a second stream of water; (d) mixing in the zone of mixing water and not necessarily the extraction solvent with the specified water stream and the specified second water stream forming and aqueous solution; (e) adding the extraction solvent to the specified water solution in the extraction zone forming a stream of extract and a stream of raffinate containing the specified metallic catalyst; and (f) separating the specified stream of extract in the separating zone forming a stream of organic impurities with a high boiling point and a stream of the removed extraction solvent. In a different version of the realisation of the method of removing the metallic catalyst from the stream of stock solution containing the carboxylic acid includes the following stages: (a) evaporating of the stock solution containing the carboxylic acid, metallic catalyst, impurities, water and solvent, in the zone of the first evaporator obtaining a stream of water and a stream of concentrated stock solution; (b) evaporating the specified stream of concentrated stock solution in the second evaporating zone obtaining a stream rich in the solvent and stream of super-concentrated stock solution, where about 85 to about 99% mass, of the solvent and water is removed from the specified stock solution at the stage (a) and stage (b) in combination; (c) removing of organic impurities from the specified super-concentrated stock solution with help of the water-solvent solution in the zone of the separating phase of solid substance/liquid forming a stream of water and a second stream of water; where the specified water-solvent solution is introduced to the specified zone of the separating phase of solid substance/liquid at a temperature interval from about 20°C to 70°C; (d) mixing in the zone for mixing water and not necessarily the extraction solvent with the specified stream of water and the specified second water stream forming a water mixture; (e) introducing the extraction solvent to the specified water solution to the extraction zone forming a stream of extract and a stream of raffinate; and (f) separating of the specified flow of extract in the zone of separation forming a flow of organic impurities with a high boiling point and a flow of the extraction solvent removed.

EFFECT: increase in the efficiency of the method of removing impurities and working capacity of the method in comparison to the existing methods.

17 cl, 1 tbl, 1 dwg

FIELD: chemistry.

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

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

8 cl, 1 tbl, 1 dwg, 1 ex

FIELD: chemistry.

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

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: chemistry.

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

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: chemistry.

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

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

19 cl, 1 dwg, 6 ex, 4 tbl

FIELD: carbon materials and hydrogenation-dehydrogenation catalysts.

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

EFFECT: increased mechanical strength and abrasion resistance.

8 cl, 4 ex

FIELD: industrial production of methacrylic acids at reduced amount of industrial wastes.

SUBSTANCE: proposed method is performed by catalytic oxidation of propane, propylene or isobutylene in vapor phase at separation of final product and forming of high-boiling mixture as by-product which contains (according to Michaels addition) water, alcohol or methacrylic acid added to methacrylic group. By-product is decomposed in thermal decomposition reactor at simultaneous distillation of decomposition products in distilling column from which methacrylic acid is taken in form of distillate. Flow of liquid decomposition residue is forced for peripheral direction by means of mixing blades before withdrawal from reactor. Peripheral direction is obtained with the aid of liquid fed from the outside of decomposition reactor; to this end use is made of initial high-boiling material or flow of liquid discharged from decomposition reactor. If necessary, etherification stage is performed through interaction with alcohol for obtaining methecrylic ester. Decomposition of by-product formed at obtaining methacrylic acid by oxidation of propylene or isobutylene or at obtaining methacrylic acid by interaction of acid with alcohol by alcohol through introduction of by-product into thermal decomposition reactor provided with distilling column which has plates made in form of disks and toroids for simultaneous decomposition and distillation. Plant proposed for realization of this method includes thermal decomposition reactor and distilling column, level meters and lines for discharge of liquid containing easily polymerized compounds. Level indicator mounted at area of accumulation of liquid shows pressure differential. Line for detecting the side of high pressure of this level meter is connected with accumulated liquid discharge line.

EFFECT: updated technology; increased yield of target products.

38 cl, 14 dwg, 2 tbl, ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of reducing and/or removing reducing permanganate compounds (RPC), carboxylic acids C3-8 and C2-12 of alkyl iodide compounds, formed during carbonylation of a carbonylation-capable reagent, chosen from a group consisting of methanol, methylacetate, methyl formate, dimethyl ether and their mixture, into commercial-grade acetic acid, in which products of the said carbonylation include a volatile phase, which is distilled thereby obtaining purified commercial-grade acetic acid and the first distillate, containing methyl iodide, water and at least one reducing permanganate compound, where improvement includes stages: (a) separation of the obtained first distillate into a light and a heavy phase, with subsequent distillation of at least part of the light phase for obtaining a second distillate, containing methyl iodide, dimethyl ether and at least said one reducing permanganate compound, which is taken to the next distillation stage, where a stream is formed as distillate, containing reducing permanganate compound; (b) addition of dimethyl ether into supply of said stream containing reducing permanganate compound, and extraction of this stream with water to form the first raffinate and first aqueous extraction stream, containing at least said one reducing permanganate compound; and (c) extraction of the first raffinate with water to form the second raffinate and second aqueous extraction stream, containing at least said one reducing permanganate compound. Invention also relates to a method of separating a mixture, containing water, acetic acid, methyl iodide, methyl acetate, methanol and at least one reducing permanganate compound (RPC), obtained by separating the liquid-vapour phase of the output stream of the methaol carbonylation reactor to form a vapour phase and a liquid phase, distillation of the vapour phase to form a liquid product which contains acetic acid, and first distillate, condensation of at least part of the first distillate thereby obtaining a liquid composition which contains methyl acetate, methyl iodide, water, methanol and at least one reducing permanganate compound (RPC), separation of the obtained liquid composition into a light and a heavy phase, which includes methyl iodide, where the light phase is the said mixture, where the said method involves stages: (a) distillation of the mixture to obtain a second distillate which contains at least one reducing permanganate compound (RPC), which is taken for the next distillation stage, where a stream is formed as distillate, containing reducing permanganate compound and dimethyl ether; and (b) extraction of concentrated reducing permanganate compound with water, where stage (b) includes at least two consecutive extraction stages, where each extraction stage involves bringing concentrated reducing permanganate compound into contact with water and separation of the aqueous stream, containing at least said one reducing permanganate compound, where dimethyl ether is added to the said distillate stream concentrated with reducing permanganate compound before extraction of the concentrated reducing permanganate compound with water.

EFFECT: process is described for removing reducing permanganate compounds from a stream from carbonylation of methanol.

28 cl, 2 dwg

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