Method of producing acetic acid

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

 

Description of the prior art

1. The technical field to which the invention relates

The present invention relates to an improved method of producing acetic acid by carbonyliron methanol.

2. Prior art

Among the currently used methods of obtaining acetic acid is one of the most commercially successful is the catalytic carbonylation of methanol with carbon monoxide, as disclosed in U.S. patent No. 3769329 issued Paulik et al. October 30, 1973, the Catalyst for carbonylation contains rhodium, or dissolved or otherwise dispersed in a liquid reaction medium or deposited on an inert solid substance, together with such halogen-containing catalyst promoter as methyl iodide. Rhodium can be introduced into the reaction system in any of many forms, and the exact nature of the rhodium component in the active catalytic complex is uncertain. Similarly, the nature of the halide promoter is not critical. The patentees disclose a very large number of suitable promoters, most of which are organic iodides. Traditionally and effectively the reaction is carried out with continuous bubbling fluidised bed gas of carbon monoxide che is ez liquid reaction medium, in which dissolve the catalyst.

In the prior art, the main improvement of the method carbonylation of the alcohol with obtaining a carboxylic acid having one carbon atom more than the alcohol, in the presence of a rhodium catalyst disclosed in the U.S. patent No 5001259 (issued March 19, 1991); 5026908 (issued June 25, 1991) and 5144068 (issued September 1, 1992) and the European patent No EP 0161874 B2, published July 1, 1992. In the above patents disclose the way in which acetic acid is produced from methanol in a reaction medium containing acetate, methyl halide, especially methyl iodide, and a catalytically effective concentration of rhodium. These patent owners revealed that the catalytic stability and performance of the carbonylation reactor can be maintained at surprisingly high levels, even at very low concentrations of water, 4 wt.% or less in the reaction medium (despite the common industry practice of maintaining approximately 14 wt.% or 15 wt.% water), maintaining in the reaction medium, along with a catalytically effective amount of rhodium, at least, a limited concentration of water, methyl acetate and methyl iodide, given the concentration of iodide ion in addition to the content of iodide, which is present in the form of methyl iodide or other organic iodide. Th is bit-ion is present as a simple salt, and lithium iodide is preferred. In the patents found that the concentration of acetate and Yudenich salts are essential parameters influencing the rate of carbonylation of methanol upon receipt of acetic acid, especially at low concentrations of water in the reactor. Using relatively high concentrations of acetate and iodide salts obtained a surprising degree of stability of the catalytic system and the performance of the reactor, even when the liquid reaction medium contains water with concentrations reduced to about 0.1 wt.%, so small that it can be defined simply as "minimum-maximum concentration" of water. In addition, the used, the reaction medium improves the stability of the rhodium catalyst, i.e. its stability against sedimentation, especially during the stages of extraction of the product in the process. The distillation is conducted in the process for extraction of acetic acid with the ability to remove ligands of carbon monoxide from the catalyst. These ligands have a stabilizing effect on the rhodium in an environment that is supported in the reaction vessel. U.S. patent No. 5001259, 5026908 and 5144068 included in this description by reference.

Also found that, although the way carbonylation system water content in the production of acetic acid leads to the reduction of these by-products, as carbon dioxide, hydrogen and propionic acid, the amount of other impurities usually present in trace quantities, will also increase, and as acetic acid, sometimes worse, when attempts are made to increase the speed of its production by the improvement of catalysts or modification of the conditions of the reactions. These trace amounts of impurities affect the quality of the product acetic acid, especially when they are recirculated in the process. Cm. Catalysis of organic reactions (Catalysis of Organic Reactions) 75, 369-380 (1998) for further discussion of the role of impurities in the system by reaction of the carbonyl.

The crude product acetic acid is usually distilled in one or more distillation columns to remove the reaction component of the low-boiling fractions (usually methyl acetate and methyl iodide, water and impurities with high boiling fractions. Previously it was found that it is particularly important to avoid the return of large quantities of methyl iodide back to the column distillation of low-boiling fractions, because the separation of low-boiling fractions from the reaction of acetic acid is greatly diminished, if there is a possibility of the return of methyl iodide in the distillation column of the low-boiling fractions. Usually the return methyl iodide prevent by separating the greater part of methyl iodide from the top shoulder straps low-boiling fractions in the form a separate phase, but under certain conditions the upper shoulder straps low-boiling fractions may form a single liquid phase, which includes methyl iodide. The present invention provides a single way of maintaining the status of the specified single phase in the column of the low-boiling fractions.

The invention

In one aspect of the present invention, a method of obtaining acetic acid, which comprises the following stages: the interaction of carbon monoxide with such a substance capable of carboxylation as methanol, methyl acetate, methylformate and dimethyl ether or mixtures thereof in a reaction medium containing water, methyl iodide and the catalyst to obtain a product containing acetic acid; the implementation of the gas-liquid separation of the reaction product to obtain legisprudence phase containing acetic acid, water and methyl iodide, and less legisprudence phase containing the catalyst; distilling legisprudence phase to obtain a purified acetic acid and the first upper shoulder strap, containing water, methyl acetate and methyl iodide; phase separation of the first upper shoulder strap for receiving the first liquid phase containing water and a second liquid phase containing methyl iodide; and adding dimethyl ether, at least one reaction product, it is easy and is paramasa phase, the first upper shoulder strap, or stream associated with distillation, to increase separation of the first upper ring with the formation of the first and second liquid phases.

Another aspect of the present invention is an improved method of distilling a mixture containing acetic acid, methyl iodide and water, to obtain the product purified acetic acid, the first liquid phase containing water and a second liquid phase containing methyl iodide. In the developed method, the fraction of the top ring when the distillation is separated to form the first and second liquid phase, and a portion of the first liquid phase return on irrigation as phlegmy distillation. The improvement involves the addition of dimethyl ether to the mixture, to the upper shoulder strap or phlegm first liquid phase in a quantity effective to increase the phase separation of the first and second liquid phases.

Brief description of drawings

The drawing is a block flow diagram describing process of the present invention.

Despite the fact that the invention permits of various modifications and alternative forms, specific embodiments of shown as an example in the drawings and will be described in detail in this publication. However, it should be understood that the invention is not implied under the restrictions, associated with a specific open forms. Rather, it is understood that the invention covers all modifications, equivalents and alternatives included in the scope of the invention, which is defined in the attached claims.

Description of illustrative options

Illustrative variant of the present invention is described below. In the interest of clarity, not all features of actual implementation described in this description. Of course, it will be clear that the development of any such actual variant requires numerous specific to the implementation of solutions to achieve the specific goals of the developer, such as the constraints associated with the system and related commercial interests, which will vary from one option to another. In addition, it will be clear that such attempts developments can be difficult and time-consuming, but, nevertheless, can be a common practice for specialists in this field, using the advantages of this discovery.

The present invention is useful in any way, use the carbonylation of methanol with the formation of acetic acid in the presence of a metal catalyst of group VIII, such as rhodium and iodide promoter. In particular, a useful method is rhodium-catalyse is consistent carbonylation of methanol at low water content with the formation of acetic acid, as illustrated above-mentioned U.S. patent No. 5001259. The rhodium component of the catalyst system can be provided by the introduction of rhodium in the reaction zone in the form of metallic rhodium, of rhodium salts such as oxides, acetates, iodides, etc. or other coordination compounds of rhodium.

Halogen-activating component of the catalytic system includes organic halide. Thus, the alkyl-, aryl - substituted alkyl - or aryl-halides, can be used. Preferably the halide promoter is present in the form of alkyl-halide, in which alkilirovanny radical corresponds alkilirovannami the radical insertion of alcohol, which carbonyliron. Thus, when carbonyliron methanol with the formation of acetic acid halide promoter is methyl halide, and preferably iodide stands.

Used liquid reaction medium may include any solvent compatible with the catalyst system, and may include pure alcohol or alcohol mixture of raw materials, and/or the desired carboxylic acid and/or esters of these two compounds. The preferred solvent and liquid reaction medium in the way carbonylation with low water content is the product of a carboxylic acid as such. Thus, when carbonyliron is the ethanol with the formation of acetic acid is the preferred solvent is acetic acid.

Water present in the reaction medium at concentrations much lower than those initially practically assumed to achieve a significant rate of reaction. Previously believed that in the rhodium-catalyzed carbonylation reactions of the type described in the present invention the addition of water has a beneficial effect on the reaction rate (U.S. patent No. 3769329). Thus, in most cases, the industrial implementation of the method was carried out at concentrations in water of at least about 14 wt.%. Accordingly, it was entirely unexpected that the reaction rate is essentially equal to and greater than the rate of reaction obtained with such high levels of water can be achieved with a concentration of water of less than 14 wt.% and to as low as about 0.1 wt.%.

In accordance with the method carbonyl most effective for the production of acetic acid according to the present invention, the desired reaction rate even at low concentrations of water are added to the reaction medium of acetate and an additional iodide ion, which complements the iodide present as a catalytic promoter, for example methyl iodide or other organic iodide. Additional iodide promoter is a salt of iodide, site is preferably lithium iodide. It is established that at low concentrations in water methyl acetate and lithium iodide act as promoters speed only when each of these components are present in relatively high concentrations, and that the activation becomes higher when there are simultaneously both (U.S. patent No. 5001259).

The carbonylation reaction of methanol with the formation of acetic acid may be carried out by the interaction of raw materials methanol, which is usually in the liquid phase, with gaseous carbon monoxide, barotrauma through the liquid acetic acid, solvent reaction medium containing a rhodium catalyst, methyl iodide as promoter, methyl acetate, and additional soluble salt of iodide at a temperature and pressure suitable to form the carbonylation product. Usually consider what is important is the concentration of iodide ion in the catalytic system, and not the cation associated with the iodide, and that when selected molar concentration of iodide nature of the cation is not as significant compared to the effect of the concentration of iodide. Therefore, any salt of a metal iodide or an iodide salt of any organic cation, or a Quaternary cation, as a Quaternary amine or phosphine, or inorganic cation can be used, provided that the sufficiently soluble in the reaction medium, to provide the desired level of iodide. When iodide is added as a metal salt, preferably, that it is an iodide salt of a representative group consisting of metals of group IA and group IIA of the periodic table, as described in the Handbook of Chemistry and Physics published by CRC Press, Cleveland, Ohio, 2002-03 (83rd edition). In particular, suitable iodides of alkali metals and preferred lithium iodide. In the method of carbonylation with low water content, the most suitable in the present invention, the added iodide supplements organic ideny promoter present in the solution of the catalyst in an amount of from about 2 to about 20 wt.%, the acetate is present from about 0.5 wt.% to about 30 wt.% and lithium iodide is present from about 5 wt.% up to about 20 wt.%. The rhodium catalyst is from about 200 parts to about 2000 parts per million by weight (ppm).

The typical temperature of the carbonylation reaction is from about 150C to about 250C, preferably from about 180C to about 220C. the Partial pressure of carbon monoxide in the reactor can vary widely, but typically is from about 2 atmospheres to about 30 atmospheres and preferably from about 3 atmospheres to about 10 atmospheres. Due to the partial pressure of by-products and the vapor pressure with eradica liquids total pressure in the reactor will be in the range of about 15 atmospheres to about 40 atmospheres.

A typical reaction system and the extraction of acetic acid, used for the iodide-activated rhodium-catalyzed carbonylation of methanol with the formation of acetic acid, shown in the drawing. The reaction system includes a carbonylation reactor 10, the evaporator 12 and the column distillation of low-boiling fractions methyliodide/acetic acid 14, which has a lateral diversion of the flow of acetic acid 17, which is sent for further purification. As disclosed in U.S. patent No. 5416237, incorporated herein by reference, in column distillation of low-boiling fractions 14 may also be additional stages that facilitate the separation of acetic acid and water, eliminating thus the need for a separate dehydration column for the implementation of this division. The carbonylation reactor 10 is typically a tank with an agitator or a bubble column, in which the levels of liquid reactive component are supported automatically. Inside the specified reactor continuously introduce fresh methanol via stream 6, carbon monoxide via stream 8, a sufficient amount of water required to maintain at least the minimum limit of water concentration in the reaction medium, recirculating catalytic solution through the flow of the 13 from the bottom of the evaporator 12, recirculating phase methyl iodide and methyl acetate 21 and recirculating the aqueous phase acetic acid 36 of the upper ring-receiving compartment of the decanter for low-boiling methyl iodide and acetic acid or the separation column 14. The distillation system is used to ensure the extraction of crude acetic acid and recycling the catalyst solution, methyl iodide and methyl acetate in the reactor. In one preferred method, the carbon monoxide is continuously introduced into the carbonylation reactor with stirrer slightly below the agitator, thus fully dispersive carbon monoxide through the reaction liquid. Gaseous purge stream produced from the reactor to prevent the accumulation of gaseous by-products and to regulate the partial pressure of carbon monoxide at a given total reactor pressure. The temperature of the reactor control and raw material of carbon monoxide injected at a rate sufficient to maintain the desired total pressure in the reactor.

Liquid product is removed from the carbonylation reactor 10 at a rate sufficient to maintain a constant level, and sent to the evaporator 12. In the evaporator the catalytic solution is extracted as the main thread (mainly acetic acid containing rhodium katal is the congestion and the iodide salt along with small amounts of acetate, iodide, bromide and water), while the gas flow of the upper shoulder strap evaporator contains the crude product is acetic acid, along with some amounts of methyl iodide, methyl acetate and water. Thread 11 leaving the reactor and entering the evaporator, also contains dissolved gases, including the proportion of carbon monoxide along with gaseous byproducts, such as methane, hydrogen and carbon dioxide. They come out of the evaporator as part of the gas flow of the upper ring 26 which is sent to the column of light fractions or the splitter column 14.

From the upper part of the column of light fractions or the separation column 14 of the pair is removed via stream 28, condensed and sent to the decanter 16. Stream 28 contains capable of condensing water, methyl iodide, methyl acetate, acetaldehyde and other carbonyl components, and also such is not capable of condensing gases, such as carbon dioxide, hydrogen, and the like, which may be released in the stream 29, as shown in the drawing. Capable of condensing vapors is preferably cooled to a temperature sufficient for this, and divide capable of condensation of methyl iodide, methyl acetate, acetaldehyde and other carbonyl components and water into two liquid phases. At least part of the stream 30 is directed back into the column of light fractions 14 as the flow of phlegmy 34; in a preferred embodiment of the invention another part of the thread 30 to divert as side stream 32 and handle to remove acetaldehyde and other permanganate restored compounds (PVA) before it is returned to the reaction system or column of light fractions. Several processing methods known in the field of machinery removal of acetaldehyde and other PVA; examples of such methods are disclosed in U.S. patent No. 5625095, 5783731, 6143930 and 6339171, each of which is incorporated herein by reference in full. With the aim of preserving the water balance during the process the other remaining part 41 of the light phase 30 may be released from the system or has been processed to remove additional water before it is returned to the reaction system.

Heavy phase 21 of the thread 28, leaving the upper shoulder of the receiving compartment of the decanter 16, usually recycle to the reactor, but part of the flow, usually a small number, for example 25%, preferably less than about 20 vol.%, the heavy phase may also be directed to the method of removal of the PVA and the remainder recycled to the reactor or reactor system. A specified part of the flow of heavy phase can be processed separately or combined with a light phase stream 30 for further distillation and extraction of carbonyl impurities

As explained earlier, is especially desirable to maintain a low concentration of water, for example below 8% and preferably much lower, in the reaction medium carbonylation, at least for two reasons: first, maintaining a low concentration of water allows you to control the amount of carbon dioxide formed as a by-product in the reactor in the shift reaction equilibrium phase water-gas. Secondly, and more importantly, low concentrations of water can also help to control the amount of propionic acid produced as a by-product. Although the concentration of water in the reaction medium is reduced, the steam load on the column 14 increases. This increased steam load causes unacceptably high transfer of acetic acid in the decanter 16 with the upper part of the column of light fractions 14. Dissolution of acetic acid as iodide in the stands and in the aqueous phase causes the deterioration of the phase separation, which ultimately leads to a single liquid phase in the decanter. When this mode is phlegm in the column 14 includes methyl iodide in a high concentration. The presence of the specified additional methyl iodide greatly limits the capacity of the column 14 to the exact separation of the substance of light fractions, such as the acetate, the product is the acetic acid 17. In this situation, it is often required that the reaction system as a whole has stopped working up until the problem can be resolved. (For this reason, only the light phase 30, which contains a relatively small amount of methyl iodide, typically used as phlegmy columns 14.)

Due to the said possible problems, it is extremely important to maintain the phase separation in the decanter 16, even despite the fact that it is more difficult to do because of the conditions of the reaction in conditions with low water content and because of the trend of acetate with a high concentration to create a high steam load in the column of light fractions, which stimulates the formation of a single phase, as mentioned above. Although this problem has been recognized to some extent in U.S. patent No. 5723660, the disclosure of which is incorporated herein by reference, there are solutions proposed involve such expensive stage, as the distilling of the upper ring of light fractions to remove methyl acetate or a significant lowering of the temperature to which you want to cool the upper part of the light fraction before it will be available in the decanter. The third proposed solution is to implement a periodic flow of water in a column of light fractions for guaranteed maintain the concentration of acetate is below 40 wt.%, that will, of veroia is but to a significant change of water balance in the whole process every time you add water.

The authors of the present invention have found another effective way to provide phase separation of the upper ring of light fractions of the decanter 16 without using any complicated stages proposed in U.S. patent No. 5723660, and without significant changes of the water balance in the process. In more simple terms, the inventors have found that a suitable phase separation in the decanter can be provided by adding a component which (a) is immiscible with water; (b) compatible with the process chemistry and (c) counteracts the effect of acetic acid on the activation of one phase. In particular, the inventors have found that the addition of dimethyl ether (DME) for light fractions of the upper shoulder strap, easy fractions of the raw material of the column or to another thread that is associated with a column of light fractions 14, the liquid contents of the decanter 16 can be protected from the formation of one phase.

In addition, as almost immiscible with water, DME compatible with the process chemistry. As explained above, organic (enriched with iodine stands for the heavy phase, formed in the decanter 16, returned to the carbonylation reactor 10. DME reacts with water and is onoxide carbon in the conditions of the reaction of carbonyl with the formation of acetic acid. In addition, as disclosed in U.S. patent No. 5831120 because carbonylation of dimethyl ether is accompanied by the consumption of water, DME is also favorable to monitor the accumulation of water in the process. For example, additional water used carbonyliron DME can make unnecessary blowing or the processing part 36 light phase 30, which is returned to the reactor to remove additional water. Finally, the presence of DME in the side stream 32 light phase 30, which is then treated to remove acetaldehyde, leads to favorable effects. That particularly applies to the case, as disclosed in more detail in conjunction considering applications for the grant of a U.S. patent 10/708420 and 10/708421 lodged there at the same time, when enough DME is present in the side stream 32 light phase or formed directly on the place in the removal of acetaldehyde, undesirable loss of methyl iodide during the process of removal of acetaldehyde significantly reduced.

It was considered that such technological processes of production of acetic acid, as described above, several recycle streams within the field of purification or purification to the reaction system. Therefore, DME can be added anywhere in the process is essah provided that a sufficient amount of DME is accumulated in the decanter of light fractions 16 to achieve there desired effect of increasing the phase separation. For example, DME can be entered (via stream 37) in the upper part of the evaporator 26, which carries the feed to the column of light fractions 14, or may be made separately in column (via stream 38). Alternative DME can be entered in the column of light fractions through the flow phlegmy 34. Currently, however, believe that the submission of additional DME through the column of light fractions 14 can make an excess contribution to a steam load in the column. Accordingly, it is preferable to add DME directly or indirectly to the decanter of light fractions 16 through a thread or series of threads that do not pass through the column of light fractions 14. For example, DME can be added directly to the flow of the upper ring of light fractions 28 (stream 35). Alternatively, in some embodiments, the implementation of the technology of removing acetaldehyde is disclosed in U.S. patent No. 6143930 and jointly consider applications for the grant of a U.S. patent 10/708420 and 10/708421 submitted it at any one time, all or part of the return flow from the system remove acetaldehyde return to the decanter 16 or in a column of light fractions 14. In addition, the DME could be added to such returned to the stream (for example, the thread 46 on the figure of 1 PA is enta USA no 6143930) or to the thread in a different place within the system of removal of acetaldehyde so, that the returned stream contains enough DME to increase phase separation in the decanter 16.

Although the invention is described with reference to preferred options, obvious modifications and changes can be carried out by specialists in this field. Therefore, it is assumed that the invention includes all such modifications and changes to the full extent as they entered the next volume next formula, invention or its equivalents.

1. The method of obtaining acetic acid, comprising the following stages:
(a) interaction of carbon monoxide with at least one reagent selected from the group consisting of methanol, methyl acetate, methylformate and dimethyl ether and mixtures thereof in a reaction medium containing water, methyl iodide and the catalyst to obtain a reaction product containing acetic acid;
(b) carrying out gas-liquid separation specified reaction product to obtain legisprudence phase containing acetic acid, water and methyl iodide and less legisprudence phase containing the specified catalyst;
(c) distillation of the specified legisprudence phase to obtain pure product of acetic acid and the first upper ring-containing water, methyl acetate and methyl iodide;
(d) phase separation of the specified first upper shoulder straps DL the first liquid phase, containing water and a second liquid phase containing methyl iodide and methyl acetate; and
(e) adding dimethyl ether directly or indirectly in the decanter of light fractions of the phase separation of the specified first upper shoulder straps in a quantity effective to increase the separation of the first upper shoulder strap for the formation of the first and second liquid phases.

2. The method according to claim 1, further comprising a stage of removal of acetaldehyde, at least one of the specified first and second liquid phases, and in which dimethyl ether is added to the stream associated with the stage of removal of acetaldehyde.

3. The method according to claim 2, in which dimethyl ether is added to the return flow from the system remove acetaldehyde.

4. The method according to claim 2, in which stage the removal of acetaldehyde includes removing acetaldehyde from a mixture comprising methyl iodide, and in which a portion of the dimethyl ether is effective for reducing the number of methyl iodide extracted from this mixture with acetaldehyde.

5. The method according to claim 1, in which at least a portion of the first liquid phase is used as a flow phlegmy by distillation of legisprudence phase.

6. The method according to claim 1, in which the second liquid phase recycle to create part of the reaction medium.

7. The method according to claim 6, in which the greater part of added dimethyl ether, reci colruyt in the reaction medium in the second liquid phase.

8. The method according to claim 7, in which at least part of the recycled dimethyl ether is converted into acetic acid in the reaction medium.



 

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27 cl, 5 tbl, 20 ex

FIELD: chemistry.

SUBSTANCE: invention relates to method of oxidising alkane from C2 to C4 with the obtaining of corresponding alkene and carboxylic acids. The method includes the following stages: (a) contact in the oxidation reaction zone of the alkane, which contains molecular oxygen gas, not necessarily corresponding to the alkene and not necessarily water in the presence of at least one catalyst, effective with the oxidation of the alkane to the corresponding alkene and carboxylic acid, alkane, oxygen and water; (b) separation in the first separating agent at least part of the first stream of products in a gaseous stream, which includes alkene, alkane and oxygen, and a liquid stream, which includes carboxylic acid; (c) contact of the mentioned gaseous stream with the solution of a salt of metal, capable of selectively chemically absorbing alkene, with the formation of a liquid stream rich in chemically absorbed alkene; (d) isolation from the flow of the solution of salt of the metal. The invention also relates to combined methods of obtaining alkyl-carboxylate or alkenyl-carboxylate (for example vinyl acetate), moreover these methods include oxidising of alkane from C2 to C4 with the obtaining of corresponding alkene and carboxylic acid, isolation of alkene from the mixture of alkene, alkane and oxygen by absorption using the solution of the salt of metal and extraction of the stream rich in alkene from the solution of the salt from metal for using when obtaining alkyl-carboxylate and alkenyl-carboxylate.

EFFECT: improved method of oxidising alkane from C2 to C4 with the obtaining of corresponding alkene and carboxylic acids.

46 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention pertains to perfection of the method of obtaining acetic acid with rate of volume flow of at least 15g-mol/l/h, a catalytic carbonylation reaction, involving reaction of a compound, chosen from a group containing methanol, methyliodide, methylacetate, dimethyl ether, or their combination, in the presence of carbon monoxide and a catalyst system based on rhodium in a reaction mixture, where the reaction mixture consists of not less than 2.0% mass, water, metal, in concentration of at least 1000 h/million, chosen from a group containing rhodium and a combination of rhodium and iridium, iodide ion in concentration from 2 to 20% weight, and a halogen promoter, chosen from a group, containing halogen-hydrogen, alkyliodide, iodine salt or acetate salt of a group IA metal, group II metal, quatanary ammonium salt, phosphoric acid salt, or their combination in concentration from 2.0% mass to 30.0% mass. The method is used for attaining reaction speed of at least 15 g-mol/l/h. The invention also pertains to the method of obtaining acetic acid from a carbonylation reaction in a system, consisting of a reaction zone and a cleaning zone, and involves the following stages: (a) reaction of methanol, methyliodide, metylacetate, dimethyl ether or their combination with carbon monoxide in the presence of a catalyst system based on rhodium in a reaction mixture, with water content from 0.1% mass to 5.0% mass, iodide ion in concentration from 2 to 20% mass, and a halogen promoter, chosen from a group, containing halogen-hydrogen, alkyliodide, iodine salt or an acetate salt of a group IA metal, group IIA metal, quaternary salt of ammonia, phosphoric acid salt or their combination, in concentration from 2.0% mass to 30.0% mass, and (b) putting a compound, chosen from a group, consisting of methylacetate, dimethyl simple ether, acetic anhydride and their mixture in the reaction zone.

EFFECT: perfection of the method of obtaining acetic acid.

26 cl, 1 dwg, 4 ex, 1 tbl

FIELD: chemical technology.

SUBSTANCE: invention relates to technology for synthesis of acetic acid by carbonylation of methanol. Method for synthesis of acetic acid is carried out by the carbonylation reaction of methanol and/or its reactive derivative in one or some reactors in the liquid reactive composition comprising iridium catalyst for the carbonylation reaction, ruthenium promoter, methyl iodide co-catalyst, methyl acetate, acetic acid and water. Liquid reactive composition from one or some reactors is fed for one or some separation steps by a single equilibrium evaporation to yield (I) vapor fraction containing component able to condensing and exhausting gas of low pressure containing carbon monoxide, and (II) liquid fraction containing iridium catalyst for the carbonylation reaction, ruthenium promoter and acetic acid as a solvent. Components able for condensing are isolated from exhausting gas of low pressure. The concentration of carbon monoxide in exhausting gas is maintained according to the formula: Y > mX + C wherein Y means the molar concentration of carbon monoxide in exhausting gas of low pressure; X means the concentration of ruthenium in the liquid reactive composition as ppm; m means about 0.012, and C means about -8.7. The concentration of carbon monoxide in exhausting gas of low pressure is in the range from 55 to 65 mole%, and the concentration of ruthenium in the liquid reactive composition is up to 5500 ppm. Method provides decreasing loss of the catalyst components at step for isolation of acetic acid based on enhancing stability of the catalytic system.

EFFECT: improved method of synthesis.

29 cl, 6 tbl, 2 dwg, 34 ex

FIELD: chemistry.

SUBSTANCE: method of (meth)acrylic acid purification includes the stages as follows: distillations of the liquid containing raw (meth)acrylic acid being acrylic acid or methacrylic acid with one or more polymerisation inhibitors added as chosen from group consisting of phenol derivative, phenothiazine derivative, copper (meth)acrylate and copper dithiourethane, for the purpose to produce condensate of (meth)acrylic acid, containing (meth)acrylic acid of purity at least 90%; adding polymerisation inhibitor containing phenol derivative to condensate; and delivery of oxygen-containing gas that contains oxygen to condensate of (meth)acrylic acid in reflux tank wherein condensate of (meth)acrylic acid is collected, wherein oxygen-containing gas is delivered to condensate in reflux tank with using small-size bubble liquid injector, and pressure connection for oxygen-containing gas delivery to liquid injector whereat ratio (nm/tn) of oxygen delivery in oxygen-containing gas and condensate flow supplied to reflux tank at 0°C, 1 atm complies with ratio shown in equation 0.004≤A/B≤1.0, where A stands for O2 delivery (nm3/hour), B stands for condensate flow (tn/hour) of the condensate supplied to reflux tank, and symbol n in nm3/hour specifies the value under normal conditions (0°C, 1 atm: normal conditions).

EFFECT: effective method of high purity acid production wherein acid polymer formation in made condensate is prevented.

12 cl, 6 dwg, 7 ex

FIELD: chemistry.

SUBSTANCE: present invention pertains to improvement of the method of producing (met)acrylic acid and complex (met)acrylic esters, involving the following stages: (A) reacting propane, propylene or isobutylene and/or (met)acrolein with molecular oxygen or with a gas, containing molecular oxygen through gas-phase catalytic oxidation, obtaining crude (met)acrylic acid; (B) purification of the obtained crude (met)acrylic acid, obtaining a (met)acrylic acid product; and (C) reacting raw (met)acrylic acid with alcohol, obtaining complex (met)acrylic esters, in the event that the installation used in any of the stages (B) and (C), taking place concurrently, stops. The obtained excess crude (met)acrylic acid is temporarily stored in a tank. After restoring operation of the stopped installation, the crude (met)acrylic acid, stored in the tank, is fed into the installation, used in stage (B), and/or into the installation used in stage (C). (Met)acrylic acid output of the installation used in stage (A) should be less than total consumption of (met)acrylic acid by installations used in stages (B) and (C).

EFFECT: the method allows for processing (met)acrylic acid, temporarily stored in a tank, when stage (B) or (C) stops, without considerable change in workload in stage (A).

2 ex

FIELD: chemistry.

SUBSTANCE: invention concerns improved method for obtaining (meth)acrylic acid involving steam phase catalytic oxidation of propylene, propane or isobutylene for production of reaction mix, absorption of oxidised reaction product in water to obtain water solution containing (meth)acrylic acid, concentration of water solution in the presence of azeotropic agent and distillation of obtained (meth)acrylic acid in distillation column to obtaining purified (meth)acrylic acid. During operation of distillation column, including operation interruption and resumption, the column is washed with water, and afterwards azeotropic distillation is performed in the presence of azeotropic agent.

EFFECT: efficient and fast cleaning of distillation column with extraction of valuable substance.

5 cl, 5 dwg, 3 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to separation of product and by-product stream in production of alkylaromatic acids, in particular terephthalic acid, via oxidation of hydrocarbon with molecular oxygen in acetic acid solution. In order to recover acetic acid, it is separated from methyl acetate in distillation column in the form of bottom stream. Distillate containing methyl acetate by-product is catalytically hydrolyzed in hydrolysis reactor using preferably water withdrawn from emission gas washing column. Non-decomposed methyl acetate is separated from methanol and recovered in the form of high-concentration aqueous solution by extractive distillation with water, after which routed back to hydrolysis so that essentially all methyl acetate by-product is recovered and reused in the form of acetic acid. Reaction mixture in the hydrolysis stage contains no more than 30% acetic acid and weight amount of water by 3 or more times exceeding amount of recovered methyl acetate.

EFFECT: improved economic characteristics of process due to reduced loss of acetic acid and additional recovery of acetic acid when performing hydrolysis of methyl acetate.

6 cl, 3 dwg, 6 tbl, 3 ex

The invention relates to an improved method of isolation and purification of adipic acid, used for the production of polyamide-6,6 or polyurethanes, which consists in treating the reaction mixture obtained by direct oxidation of cyclohexane to adipic acid by molecular oxygen in an organic solvent and in the presence of a catalyst, removing by-products from the reaction mixture and the adipic acid by crystallization, and before adipic acid from the reaction environment carry out consistently the following operations: the decantation of the two phases of the reaction medium with the formation of the upper organic the cyclohexane phase, containing mainly cyclohexane, and the lower phase, containing mainly the solvent, the resulting dicarboxylic acid, the catalyst and other reaction products and unreacted cyclohexane; distillation bottom phase to separate, on the one hand, distillate containing at least a part of the most volatile compounds, such as organic solvent, water and unreacted cyclohexane, cyclohexanone, cyclohexanol, complex cyclohexylamine esters and possibly lactones, and, with the pin acid from residue from distillation by means of crystallization and thus obtained crude adipic acid is subjected in aqueous solution purification by hydrogenation and/or oxidation with subsequent crystallization and recrystallization of the purified adipic acid in water

The invention relates to an improved method of processing the reaction mixture formed by the reaction of direct oxidation of hydrocarbons to carboxylic acids

The invention relates to the production of acetic acid

The invention relates to a method of reducing and/or removing permanganatometricly compounds, such as acetaldehyde, propionic acid and alkylidene impurities in the process of carbonylation of methanol

The invention relates to a method for producing high-purity acrylic acid (options) with a residual content of aldehydes less than 10 parts/million

FIELD: chemistry.

SUBSTANCE: invention concerns aggregate for (met)acrylic acid obtainment, including: reactor for (met)acrylic acid obtainment by catalytic gas phase oxidation reaction of one, two or more source compounds including propane, propylene, isobutylene and (met)acrolein, in gas mix of source substances including one, two or more source compounds including propane, propylene, isobutylene and (met)acrolein, and oxygen; heat exchanger connected to reactor and intended for cooling of reaction gas mix including obtained (met)acrylic acid; and absorption column connected to heat exchanger and intended for contact absorbing fluid with reaction gas mix for (met)acrylic acid absorption, so that (met)acrylic acid is absorbed from reaction gas mix by absorbing fluid. Additionally the aggregate includes: bypass pipe connecting reactor and absorption column without the use of intermediary heat exchanger; and device for flow rate adjustment in reaction gas flow passing through bypass pipe in order to maintain almost constant flow rate of gas mix feed of source materials to reactor or almost constant pressure of gas mix of source materials at the reactor inlet. Also invention concerns improved method of (met)acrylic acid obtainment by extraction of (met)acrylic acid absorbed by absorbing fluid.

EFFECT: heat power tapping from reaction gas mix, stable and continuous process even in case of heat exchanger intended for heat power extraction is blocked.

2 cl, 3 dwg, 1 ex

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