Method and apparatus for producing acetic acid with high efficiency

FIELD: chemistry.

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

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

15 cl, 4 dwg, 2 tbl

 

The technical field to which the invention relates.

The present invention generally relates to a device and method for acetic acid, and the product is extracted from the remainder of the column for distillation of light fractions and served further to improve the performance of the system.

The level of technology

The carbonylation processes well known in this technical field. Special commercial importance of these processes for the carbonylation of methanol to obtain acetic acid and processes for the carbonylation of methyl acetate to obtain acetic anhydride. See Applied Homogenous Catalyst With Organometallic Compounds, Cornils et al., Ed. (Bench Edition) (Wylie, Weinheim, Federal Republic of Germany, 2000), Chapter 2, Parts 2.1.2 and forth, pp.104-137. See also U.S. patent No. 6642413 issued Thiebaut.

For acetic acid is one selected method comprises the carbonylation of methanol in a homogeneous reaction medium in which the catalyst is rhodium. Usually, the reaction medium includes a catalyst, water, acetic acid, dissolved carbon monoxide (CO), methanol, methyl acetate (Meac), idiscovered acid (HI), methyl iodide and possibly one or more promoters and/or stabilizers. Methanol and carbon monoxide are fed into the reactor as raw materials. Part of the reaction medium continuously withdrawn and fed into the COI is ritel instant action, where the product evaporates and is filed (as vapor) in the sequential treatment. System consistent cleaning includes a column for distillation of light fractions, which removes the "light", or boiling components, such as upper shoulder strap, and provides a stream of product to further purification. Particularly preferred carbonylation process is proposed in U.S. patent No. 5144068, issued to Smith et al. In this so-called "low-water" the process of such an alcohol, like methanol, is reacted with carbon monoxide in a liquid reaction medium containing a rhodium catalyst, stable iodide salt, especially a lithium iodide with iodine stands and acetate in predetermined proportions. At finite concentration of water in the reaction medium, the product is a carboxylic acid, instead of, for example, anhydride. The reaction system for U.S. patent 5144068 not only provides the acidic product with unusually low water content with unexpectedly preferred speeds, but also exhibits unexpectedly high stability of the catalyst. That is, the catalyst is resistant to its precipitation from the reaction medium.

Another selection method for carbonylation of methanol involves the use of a homogeneous iridium catalyst in the reactor. For example, disclosed in U.S. patent No. 5883295 issued by the om Sunley et al., the process of obtaining acetic acid, comprising carbonylation with carbon monoxide to methanol and/or its reactive derivative at the substantial absence of a metal promoter and/or iodide ion copromotor in the carbonylation reactor for containing a liquid reaction composition with iridium catalyst in the carbonylation process, socialization of methyl iodide, water, acetic acid and acetate, which are as follows supported in this liquid reaction composition: (a) water at a concentration of less than 5 wt.%; (b) methyl iodide at a concentration of greater than 12 wt.%; (C) when the total pressure in the carbonylation reactor for less than 50 bar. See also U.S. patent No. 5877348 issued Ditztel et al., and U.S. patent No. 5887347, also issued Ditzel et al.

Frequent production limiting step of cleaning product in the apparatus for acetic acid is a column for distillation of light fractions. Typical apparatus carbonylation for acetic acid is running so that the product is withdrawn from the column for distillation of light fractions in the form of a side stream and a liquid residue in the column for distillation of light fractions is recycled to the reactor. This residue also contains Rh and Li, which are washed out of the vapor supplied to the column for distillation of light fractions. In the known system the rest of agcih fractions is cooled and then is recycled to the base of the apparatus for flash evaporation, whence it is pumped back into the reactor pumps for recirculation of the catalyst. Thus, the acetic acid in the flux residue is a recycling of the acid, which adds the hydraulic load to the column for distillation light ends.

The invention

The present invention includes a processing flow of the residue from light fractions to separate parts of acetic acid from the residual stream and reducing the amount of acid which is recycled to the reaction system. The installation preferably operates so that the residual flow from the column was predominantly acetic acid with small amounts of MeI, Meat and water. This processing can be done in several ways. Firstly, the residue from the column of light fractions can instantly vaporize in the tank is supported in the vacuum state. Models show that the instantaneous evaporation of the residual flow at an absolute pressure of 5 psia (34478,75 PA) allows you to retrieve approximately 50% of the acid present in the flow of residue, and the resulting temperature in the tank for flash evaporation can be, for example, about 185°F (85°C). More significant part in the percent of acetic acid is removed from the flux residue when working with even lower vacuum. The flow of vapors from the vacuum evaporation tank can be with ondansetron and filed in the column for dehydration together with a side stream from the column for distillation light ends or compressed by the compressor (used to create a vacuum) and filed in the drying column as hot steam.

In another embodiment of the flow of residue from the column for distillation of light fractions are processed in a small distillation column that separates the upper shoulder straps lightweight components (MeI, Meat and water), returns the concentrated residue in the reaction system and remove acetic acid in the form of a side stream product. The lateral flow of the product is then combined with the residue from the drying column in the form of product standard of quality, if it is sufficiently purified. Otherwise, the side stream product will be fed into the drying column.

The advantages of the present invention are measured with reference to figure 1, which is a graphical representation showing the percentage of acid extracted from the flow balance of light fractions, and its influence on the load of the column. In figure 1 you can see that over 40% of the acid in the flux residue from the distillation columns of light fractions can be retrieved with a simple instant evaporation flux and that the hydraulic load of the column for distillation of light fractions significantly reduced when a given performance.

Other distinctive features and advantages of the present invention are discussed below.

Brief description of drawings

Below the invention is described in detail with reference to the drawings, in which identical parts are denoted by the same numeral is and which are:

figure 1 - graph showing the effect of the use of the tank for flash evaporation to remove acid from the flow of the residue from light fractions and hydraulic loading on the column distillation light ends;

figure 2 is a block diagram showing the installation according to the invention, which provides a reservoir for flash evaporation of the flux residue from the column for distillation of light fractions in the device for producing acetic acid;

figure 3 is a block diagram showing the installation according to the invention, which has a distillation column for the flow of residue from the column of light fractions in the device for producing acetic acid, and

4 is a block diagram of distillation columns eye type, which can be used for flux residue from the column for distillation of light fractions in the device for producing acetic acid in accordance with the invention.

Description of the preferred embodiments

Below are described the invention with reference to numerous embodiments, only to show examples and to illustrate. Modifications of the specific embodiments in accordance with the spirit and scope of the present invention set forth in the attached claims, will be readily understandable to experts in this field.

The terminology used here, if it is not SP is specifically defined below, given its ordinary meaning. %, ppb (h/bn) and similar terms refer to the percent of mass, the mass parts per billion, and so on, unless stated otherwise.

"Distillation column", and similar terms refer to cleaning equipment, which evaporates the liquid (or at least part of it), by at least partially applying heat to the liquid.

"Distilling" and similar terms refer at least to a partial purification of a liquid by using distillation columns.

"Reservoir for flash evaporation" and similar terms refer to the tank, intended for evaporation of the liquid, at least partially, by reducing the pressure, instead of applying heat. Equipment that vaporizes at least a portion of the liquid by applying heat and pressure reduction, is considered a distillation column for the purpose of the present invention.

"Instantly vaporize", "flash vaporization" and so on refer to the evaporation of the liquid by lowering the pressure.

"Installation for the distillation or othonna column" and similar terms refer to the tank, which receives the fluid flow from the top or near the top from a single piece of equipment, and not from the column, which returns the phlegm in his the own condensed distillate.

A catalyst of group VIII can be rhodium and/or iridium catalyst. Rhodium metal catalyst may be added in any suitable form so that the rhodium was in a catalytic solution as an equilibrium mixture comprising anion [Rh(CO)2I2]-as is well known in this technical field. Iodide salt, perhaps in reaction mixtures in the processes described herein may be in the form of soluble salts of alkaline or alkaline-earth metal or a Quaternary ammonium or postnasal salt. In some embodiments the catalytic copromotion is lithium iodide, lithium acetate, or a mixture thereof. Copromotor in the form of a salt can be added as naididae salt, which will cause the formation of iodide salt. The stabilizer iodide catalyst may be introduced directly into the reaction system. Alternatively, the iodide salt may be formed in situ due to the fact that under the conditions of the reaction system a large number of precursors neitiznot salts react with methyliodide with the formation of the corresponding stabilizer copromotor in the form of iodide salts. For additional details on rhodium catalysis and formation of iodide salts, see U.S. patent 5001259, issued to Smith et al.; and 5144068, also issued to Smith et al., to the which is here mentioned in the references.

Similarly iridium catalyst in the liquid reaction composition for carbonylation may include any compound containing iridium, which is soluble in the liquid reaction composition. Iridium catalyst may be added to the liquid reaction composition for carbonylation in any suitable form, which is soluble in the liquid reaction composition or can be converted into a soluble form. Examples of suitable compounds containing iridium, which can be added to the liquid reaction composition include: IrCl3, IrI3, IrBr3, [Ir(CO)2I]2, [Ir(CO)2Cl]2, [Ir(CO)2Br]2, [Ir(CO)2I]-H+, [Ir(CO)2Br2]-H+, [Ir(CO)2I4]-H+, [Ir(CH3)I3(CO2)]-H+Ir4(CO)12, IrCl3·3H2O, IrBr3·3H2O Ir4(CO)12metal iridium, Ir2O3, Ir(acac)(CO)2, Ir(acac)3acetate iridium [Ir3O(OAc)6(H2O)3][OAc] and hexachloroiridium acid [H2IrCl6]. The iridium complexes that do not contain chlorides, such as acetates, oxalates and acetoacetates, are usually used as starting materials. The concentration of the iridium catalyst in the liquid reaction composition may be in the range from 100 to 6000 hours/billion By boilerhouse methanol using the iridium catalyst is well known, and in General it is described in the following U.S. patents: 5942460, 5932764, 5883295, 58772347 and 5996284 that are mentioned in the references of this application in its entirety.

Haloalkyl socialization/promoter is typically used in combination with a metal catalyst of group VIII. Methyl iodide is preferred as haloalkylthio promoter. Preferably, the concentration of the alkyl halide in the liquid reaction composition is in the range of from 1 to 50 wt.%, preferably from 2 to 30 wt.%.

Haloalkyl the promoter may be connected to the stabilizer/copromotion in the form of such compounds as salt, which may include a metal salt of group IA or group IIA, or Quaternary ammonium or fosfonovoi salt. Especially preferred are iodide or acetate salt, such as lithium iodide or lithium acetate.

Can be used with other promoters and copromotor as part of the catalytic system of the present invention, as described in European patent publication EP 0849248, which is mentioned here in the links. Suitable promoters choose from such as ruthenium, osmium, tungsten, rhenium, zinc, cadmium, indium, gallium, mercury, Nickel, platinum, vanadium, titanium, copper, aluminum, tin, antimony, and more preferably selected from such as ruthenium and osmium. Special soprema the ora is described in U.S. patent No. 6627770, shown here in the links.

The promoter may be present in an effective amount up to its limit of solubility in the liquid reaction composition and/or in any of the treated streams recycled to the carbonylation reactor for the stage in the extraction of acetic acid. When using the promoter is suitably present in the liquid reaction composition at a molar ratio between the promoter and the metal catalyst, is equal to [0.5 to 15]:1, preferably from 2 to 10]:1, more preferably from 2 to 7,5]:1. A suitable concentration of the promoter is from 400 to 5000 hours/bln

Installation or process for carbonylation, which is the subject of the invention typically includes at least the section for conducting reactions and section for cleaning. The present invention can be evaluated, for example, in connection with carbonyliron of methanol with carbon monoxide in a homogeneous catalytic reaction system comprising a reaction solvent (usually acetic acid), methanol and/or its reactive derivatives, soluble rhodium catalyst, at least a finite concentration of water, and possibly iodide salt. The carbonylation reaction proceeds when the methanol and carbon monoxide is fed to a continuous reactor. Interactive carbon monoxide may be creatures of the NGOs pure or may contain inert impurities, such as carbon dioxide, methane, nitrogen, noble gases, water and C1-C4paraffin hydrocarbons. The presence of hydrogen in the carbon monoxide and hydrogen generated in situ by the reaction of conversion of water gas, preferably maintained at a low level, for example, at a partial pressure less than 1 bar, as its presence can lead to the formation of hydrogenation products. The partial pressure of carbon monoxide in the reaction is appropriate in the range from 1 to 70 bar, preferably from 1 to 35 bar, and most preferably from 1 to 15 bar.

The pressure of the carbonylation reaction is appropriate in the range of 10 to 200 bar, preferably from 10 to 100 bar, most preferred from 15 to 50 bar. The temperature of the carbonylation reaction is appropriate in the range from 100 to 300°C., preferably in the range from 150 to 220°C. Acetic acid is usually obtained in the liquid-phase reaction at a temperature of about 150-200°C and a total pressure from about 20 to about 50 bar.

Acetic acid is normally introduced into the reaction mixture as the solvent for the reaction.

Suitable reactive derivatives of methanol include methyl acetate, dimethyl ether, methylformate and methyliodide. A mixture of methanol and its reactive derivative can be used as interacting matter in the process present Adamu invention. Preferably as interacting substances use methanol and/or methyl acetate. At least some amount of methanol and/or its reactive derivative is converted into the acetate and therefore will be present as methyl acetate in the liquid reaction composition in the interaction with acetic acid as a product or solvent. The concentration of methyl acetate in the liquid reaction composition is suitable in the range from 0.5 to 70 wt.%, preferably from 0.5 to 50 wt.%, more preferably from 1 to 35 wt.% and most preferably from 1 to 20 wt.%.

Water can be formed in situ in the liquid reaction composition, for example, by the esterification reaction between interacting methanol and acetic acid as the product. Water can be introduced into the carbonylation reactor for together with other components of the liquid reaction composition or separately from them. Water can be separated from the other components of the reaction composition is withdrawn from the reactor, and can be recycled in controlled amounts to maintain the desired concentration of it in the liquid reaction composition. Preferably, the concentration of water maintained in the liquid reaction composition is in the range of from 0.1 to 16 wt.%, more preferably from 1 to 14 wt.% and most the e preferably from 1 to 10 wt.%.

The reaction fluid is usually removed from the reactor and immediately evaporates. The flow of the crude vapor product from the apparatus for flash evaporation is sent to the purification system, which usually includes at least one column to remove light fractions and one column for dehydration. In the system for the carbonylation can only use two columns for cleaning, and they preferably operate as described in more detail in U.S. patent 6657078 issued Scates et al. and called "Low-energy process for the carbonylation", which is given in the references.

With reference to figure 2 shows a system 10 for carbonylation of the present invention. The installation 10 includes a reactor 12, the device 14 for flash evaporation, column 16 for removal of light fractions, the column 18 for dehydration, as well as the column 20 for removal of heavy fractions. The reactor 12 includes a reaction medium, and it entered the methanol and carbon monoxide. Part of the reaction medium through the pipeline 22 is fed continuously to the apparatus 14 for flash evaporation, where the crude product is instantly evaporated and the pipe 24 in the form of hot vapor is fed into the column 16 for distillation light ends.

Gaseous vent stream is normally excreted from the top of the reactor to prevent the formation of such gas is Breznik by-products, as methane, carbon dioxide and hydrogen, and to maintain the partial pressure of carbon monoxide at a given total reactor pressure. It is possible (as shown in the Chinese patent no ZL 92108244.4) using the so-called "Converter" reactor located between the reactor and the reservoir for flash evaporation (14, 114), shown in figure 2 and 3. "BOF" reactor gives the output stream comprising gaseous components, which are typically removed from a compatible solvent to extract components such as methyliodide and acetate. Gaseous purge streams from the reactor and Converter can be merged or deleted individually, and they are usually deleted or through acetic acid, methanol or mixtures of acetic acid and methanol to avoid loss of low-boiling components such as methyl iodide, in the process. If methanol is used as the output removes a liquid solvent enriched methanol from removal system usually returns to the process by connecting it with fresh methanol fed to the reactor for carbonylation - although it may be returned in any of the threads that are recirculated back to the reactor, for example, such as the remainder of the apparatus of the instant evaporation, or the flow of light fractions, or flows from the top of the column for dehydration. If acetic acid is used as the output removes a liquid solvent enriched acetic acid removal system is usually cleared from the absorbed light fractions, and the resulting depleted acetic acid is recycled back to the stage to absorb. The components of the light fraction removed from enriched acetic acid, which removes the solvent may be directly or indirectly returned to the main process in several different places, including a reactor, a plant for instant spray or columns for purification. Possible removal of gaseous purge flows through the lower part of the liquid installation for instant spray or lower part of the column for distillation of light fractions to improve the stability of the rhodium, and/or they can be combined with other gaseous output from the threads in the process (such as flows from the upper part of the cleaning column) before cleaning. These options are quite within the scope of the present invention, estimated on the basis of the above claims and the following description.

In column 16, the product is purified from light components, which are derived from the column through line 26, are condensed in the sump 28 and back piped 32 or returned to the reactor for TRU is aprovada 30, 34. Also provided, but not shown absorbers and desorption setup used for recycling of materials in the system.

The thread 40 of the pure product is given as (preferably liquid) side stream from the column 16 and fed into the drying column 18, where the partially purified product water is removed. Then the dried product is supplied by pipeline 42 to the column 20 for removal of heavy fractions, while the upper shoulder straps and this also acetic acid as the product is supplied through pipe 44, is used as phlegmy for column 18 or is recycled to the reactor via pipelines 34, 46. Acetic acid as a product is selected as the upper wrap the pipe 48 from the column 20 for removal of heavy fractions, and waste in the form of heavy fractions are removed through the pipeline 50.

In the column 16 is formed stream 60 liquid residues, which usually is recycled together with the remainder of the apparatus of the instant evaporation, however, in accordance with the invention, the thread 60 is fed into another device 62 to flash evaporation by pipeline 64, where the stream meets a reduced pressure, and thus the flow 60 at least partially evaporates, so that the device 62 for flash evaporation forms a second flow 66 vaporous product, which is applied to the capacitor 68 through the pipeline 70. Thread 66 is condensed in 68 and is eaten by pipe 72 is connected with the thread 40. The combined stream is then fed to the column 18, as shown, and subjected to further purification as described above. Instead of condensing flow 66 this stream can be compressed and fed further in the form of hot steam.

Thread 74 of the liquid residue is removed from the apparatus 62 flash evaporation and is recycled back to the reactor together with the residue from the tank 14 flash evaporation piping 76, 78.

Part of the acetic acid stream 60, therefore, is retrieved by the device 62 for flash evaporation and served on in the system, reducing the hydraulic load on the column 16 and improving performance. Usually, the beam 60 includes from about 90 to about 99 wt.% acetic acid and preferably at least 90 wt.% or at least 95 wt.%. Depending on the operating pressure of the apparatus 62 for flash evaporation of at least 10%, at least 20%, at least 30% or at least 40% acetic acid in stream 60 can be removed.

The system in figure 1 can be simulated by empirical computer model, in order to ensure that the pressure in the apparatus 62 for flash evaporation on the degree of extraction of the acid and on the load of the column in the case of a fully loaded (at the beginning of the overfill the base of the column and no apparatus for flash evaporation. Re ulitity are shown in table 1.

Table 1
Extraction of acetic acid from light fractions (LF) residues in the column through a simple flash evaporation
The pressure in the tank flash evaporation for processing of the residue from light fractions (psi)The proportion of acetic acid, extracted from the residue LFMaximum utilization of plates in the column for distillation of light fractions when working without the apparatus of the instant evaporation
Without the apparatus of the instant evaporation01
200,1940,990
150,2440,987
100,3080,984
50,4040,979
30,4660,976

Table 1 shows that the extracted over 40% of the acetic acid from the residual p is power of light fractions in the column and hydraulic load of light fractions in the column is significantly reduced. These results are graphically shown in figure 1, above.

With reference to figure 3 and 4 show another installation 100 for carbonylation according to the invention, which includes the reactor 112, device 114 for flash evaporation, column 116 for removal of light fractions, the column 118 for dehydration and column 120 for removal of heavy fractions. Various parts of the device are as described above with respect to similar components to obtain acetic acid and interconnected by pipes 122, 124, 140 and 142, and so forth, as shown in figure 3.

Instead apparatus for flash evaporation is provided by additional distillation column 162, which is served residual liquid stream 160 from the column 116 for removal of light fractions.

In column 162 is formed thread 164 of the upper straps, which can be condensed in 165 and used as a reverse flow in the column or returned to the reactor 112, and a side stream 166 product, which can be condensed or compressed and filed down the pipeline 168 or 170 or combined with the first product stream in front of the column for removal of heavy fractions. Assuming that the stream 166 is of sufficient quality, it is preferable to submit this thread directly into the column for removal of heavy fractions (i.e. feeding the stream without further removal of water), as this will also reduce the water is practical load on the column 118 for dehydration. If you want, then in the column 162 can be added methanol to reduce inorganic iodides in the product flow, as is known in the art. Similarly, column 162 can operate without condensed reverse flow, so it works as a distillation column removes type, if so required.

Using empirical computer model of the distillation column 162 was simulated to verify its ability to extract acetic acid from the residual stream of light fractions in the column. Sample residual stream of light fractions from the column were also distilleries in a laboratory setup with the configuration of the column 162. The results were compared in table 2.

Table 2
Comparison of the results of computer models and laboratory findings
The results based on the computer modelThe results on the basis of laboratory distillation
The proportion of lateral flow in the residual stream LF0,4770,424
The share of the flow of the upper straps OS is enough flow LF of 0.3320,289
The proportion of the residual flow in the residual stream LF0,1910,132
The load on the column of light distillate fractions relative to the current operation0,984
The load on the column for dehydration regarding the current operation0,968

From table 2 it is seen that the empirical model is in good agreement with laboratory data and the extraction of the residual liquid flow amounted to more than 40%. The hydraulic load on the column for distillation of light fractions is significantly reduced, and in the shown case, in which the extracted acid is fed further along the stream to the column for dehydration, the hydraulic load on the column for hydration diminishes significantly.

The invention has been described in detail and illustrated in accordance with many embodiments. Modifications in the specific embodiments within the meaning and scope of the present invention will be obvious to experts in this field. Such modifications are within the meaning and scope of the present invention, which is set out in paragraph evidenoe the claims.

1. The way carbonylation for acetic acid, including:
(a) carbonylation of methanol or its reactive derivative in the presence of water, of a catalyst selected from rhodium catalysts, iridium catalysts and mixtures thereof, of the promoter of methyl iodide to form a reaction mixture with acetic acid in the reactor;
(b) separation of flow of the reaction mixture with acetic acid in the liquid recycle stream and the first stream of the crude product containing acetic acid;
(c) feeding the first stream of the crude product in a column for distillation of light fractions;
(d) distilling stream of the crude product to remove low-boiling components as the upper ring and the formation of the first stream of purified product in the form of a side stream and a residual liquid stream, while the residual liquid stream consists mainly of acetic acid,
where the first stream of purified product is sent to the column for dehydration, after which the dried product is sent to the column for distillation of heavy fractions, and acetic acid are selected as the top product from the column for distillation of heavy fractions;
(e) evaporating at least part of the residual liquid stream to obtain a second product stream; and
(f) feeding the second product stream after condensation is whether compression for further processing after combining with the first stream of purified product in a given column for dehydration.

2. The method according to claim 1, also comprising a stage of condensation of the second product stream.

3. The method according to claim 1, also comprising a stage of compression of the second product stream.

4. The method according to claim 1, in which at least 10% of the present acetic acid evaporates from the liquid residual stream.

5. The method according to claim 1, in which at least 20% of the present acetic acid evaporates from the liquid residual stream.

6. The method according to claim 1, in which at least 30% present acetic acid evaporates from the liquid residual stream.

7. The method according to claim 1, in which at least 40% of the present acetic acid evaporates from the liquid residual stream.

8. The method according to claim 1, in which the residual liquid stream comprises at least 90 wt.% acetic acid.

9. The method according to claim 1, in which the residual liquid stream comprises at least 95 wt.% acetic acid.

10. The method according to claim 1, in which the residual liquid stream comprises from about 90 wt.% to about 99 wt.% acetic acid.

11. The way carbonylation for acetic acid, including:
(a) carbonylation of methanol or its reactive derivatives in the presence of water, of a catalyst selected from rhodium catalysts, iridium catalysts and mixtures thereof, and a promoter of methyl iodide for education in the reactor the reaction mixture with acetic sour is Oh;
(b) separation of flow of the reaction mixture with acetic acid at a first recycle stream and the first stream of the crude product containing acetic acid;
(c) feeding the first stream of the crude product in a column for distillation of light fractions;
(d) distilling stream of the crude product to remove low-boiling components as the upper ring and the formation of the first stream of purified product in the form of a side stream and a residual liquid stream, while the residual liquid stream consists mainly of acetic acid,
where the first stream of purified product is sent to the column for dehydration, after which the dried product is sent to the column for distillation of heavy fractions, and acetic acid are selected as the top product from the column for distillation of heavy fractions;
(e) distillation residual liquid stream to obtain a second stream of purified product; and
(f) feeding the second stream of purified product, taken as a side stream after condensation or compression in the column for dehydration or in a column for distillation of heavy fractions.

12. The method according to claim 11, in which the second stream of purified product without removing water from it is fed into the column for distillation of heavy fractions.

13. Device for producing acetic acid, comprising:
(a) a reactor for carbonyle the Finance methanol or its reactive derivatives in the presence of water, catalyst selected from rhodium catalysts, iridium catalysts and mixtures thereof, and a promoter of methyl iodide for education in the reactor the reaction mixture containing acetic acid;
(b) apparatus for flash evaporation, connected to the reactor and configured to input stream of the reaction mixture and separate it into (i) a liquid recycle stream and (ii) the crude first product stream containing acetic acid;
(c) a column for distillation light ends connected to the apparatus for flash evaporation, which is made with the possibility of separating the low-boiling components in the form of the top ring from the first product stream and the formation of the first stream of purified product in the form of lateral fraction, and residual liquid stream;
(d) a column for dehydration connected with a column for distillation light ends, for receiving and further purification of the first stream of purified product;
(e) a column for distillation of heavy fractions connected with the column for dehydration; and
(f) a reservoir for evaporation, is also connected with a column for distillation of light fractions, for evaporating at least part of the residual liquid stream and configured to supply a second flow of product in the column for dehydration; or a column for distillation residual liquid flux is and to obtain a second stream of purified product and intended for submission to the column for dehydration or in a column for distillation of heavy fractions, where column for distillation residual liquid stream is organoclay column.

14. Installation according to item 13, in which the reservoir for evaporation is the reservoir for flash evaporation.

15. Installation according to item 13, also including a column for removal of heavy fractions connected with the column for dehydration.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to methods of removing acetaldehyde from a mixture of methyl acetate, methanol and acetaldehyde, one of which involves: (a) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (b) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (c) returning as reflux a portion of the vapour stream which is output from the top of the column into the rectification column; and (d) removing a stream of the bottom residue poor in acetaldehyde from the rectification column, where temperature of the vapour stream from the top of the column ranges from 85°C to 115°C. The invention also relates to a method of producing acetic acid, involving: (a) cleaning the mixture of methyl acetate, methanol and acetaldehyde with removal of acetaldehyde by: (i) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (ii) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream which is output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (iii) returning as reflux a portion of the vapour stream output from the top of the column into the rectification column; and (iv) removing a stream of the bottom residue poor in acetaldehyde from the rectification column; (b) feeding the cleaned stream of bottom residue into the reaction mixture for carbonylation together with carbon oxide, where the reaction mixture for carbonylation contains water, a catalyst selected from rhodium catalysts, iridium catalysts or mixtures thereof, a promoter from methyl iodide and acetic acid; and (c) extracting acetic acid from the carbonylation mixture, where temperature of the stream which is output from the top of the column ranges from 85°C to 115°C.

EFFECT: improved methods.

15 cl, 8 dwg, 6 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of increasing catalytic activity when producing methyl acetate, involving carbonylation of dimethyl ether-based material with carbon monoxide in the presence of hydrogen in virtually anhydrous conditions at temperature ranging from more than 250°C to 350°C, in the presence of a zeolite catalyst which is efficient in said carbonylation, wherein concentration of dimethyl ether is at least 1 mol % with respect to the total amount of material.

EFFECT: improved method of increasing catalytic activity when producing methyl acetate.

13 cl, 4 ex, 3 tbl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of increasing rate of reaction without a ruthenium promoter and reducing toxicity of the catalyst system when producing acetic acid via carbonylation of methanol and/or reactive derivative thereof with carbon monoxide in at least one carbonylation reaction zone, containing a liquid reaction composition which contains an iridium carbonylation catalyst, a methyl iodide cocatalyst, water in an a limited concentration, acetic acid, methyl acetate and indium and rhenium as promoters.

EFFECT: high efficiency of the method.

16 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of preventing precipitation of a catalyst system when producing acetic acid via carbonylation of methanol and/or reactive derivative thereof with carbon monoxide in at least one carbonylation reaction zone, containing a liquid reaction composition containing an iridium carbonylation catalyst, a methyl iodide cocatalyst, water in an a limited concentration, acetic acid, methyl acetate and boron and gallium as promoters.

EFFECT: combination of boron and gallium as promoters enables to avoid problems with precipitation which are observed in ruthenium-promoted reactions, and the rate of reaction also remains the same compared with conventional ruthenium promoters.

15 cl, 2 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acetic acid through carbonylation of methanol and/or reactive derivative selected from methyl acetate, methyl iodide, dimethyl ether and mixtures thereof, carbon monoxide in the presence of a catalyst in a liquid reaction mixture containing methyl iodide and water in concentration of 0.1-30 wt %, wherein the catalyst includes a complex of a metal with a chelate-like ligand of general formula (I), wherein Z represents carbon, each of L1 and L2 represents a coordination group containing a donor P atom or a donor N atom; each R3 is independently selected from hydrogen, or a C1-C6 alkyl group, and M is selected from Rh and Ir; or general formula (II), wherein Z represents carbon, each of L3 and L4 represents a coordination group containing a donor P atom or a donor N atom, and M is selected from Rh and Ir.

EFFECT: method provides high selectivity of formation of acetic acid.

14 cl, 2 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing C1-C3 aliphatic carboxylic acid and/or the corresponding ester, by carbonylating the corresponding C1-C3 aliphatic alcohol and/or an ester or ether derivative thereof with carbon monoxide material containing hydrogen, in the presence of a catalyst containing a zeolite having at least one 8-member ring channel, said 8-member ring channel being connected with a channel formed by a ring with greater than or equal to 8 members, said 8-member ring having a window size of at least 2.5 Å × at least 3.6 Å and at least one Bronsted acid site and that zeolite has a silicon dioxide: X2O3 molar ratio of not less than 5, where X is selected from aluminium, boron, iron, gallium and mixtures thereof with the condition that the zeolite is not mordenite or ferrierite. The catalysts demonstrate considerable carbonylation activity compared to other zeolite catalysts.

EFFECT: improved method of producing C1-C3 aliphatic carboxylic acid.

41 cl, 2 tbl, 18 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acetic acid via carbonylation of methanol and/or reactive derivative thereof with carbon monoxide in at least one carbonylation reaction zone, containing a liquid reaction composition containing a iridium carbonylation catalyst, a methyl iodide cocatalyst, water in an a limited concentration, acetic acid, methyl acetate and ruthenium and at least one of niobium salt or tantalum salt as promoters.

EFFECT: method enables to conduct carbonylation with considerably smaller amounts of by-products while simultaneously maintaining an acceptable rate of reaction.

16 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for selective production of acetic acid and/or methyl acetate, with formation of small amounts of hydrocarbon by-products, involving bringing methanol and/or reactive derivative thereof, selected from dimethyl ether and methyl acetate, into contact with carbon monoxide in aqueous conditions in the presence of a ferrierite catalyst.

EFFECT: improved method for selective production of acetic acid and/or methyl acetate.

23 cl, 1 tbl, 15 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a novel catalyst for use in synthesis of aliphatic carboxylic acid containing (n+1) carbon atoms, where n denotes an integer of up to 6, and/or an ether derivative thereof by bringing an aliphatic alcohol containing n carbon atoms, and/or reactive derivative thereof, selected from dialkyl ether, ester of alcohol and alkyl halide, into contact with carbon monoxide, where said catalyst is prepared via ion exchange or saturation of the ammonium or hydrogen form of mordenite with silver, drying the saturated/ion exchange-treated mordenite and subsequent calcination of the dried silver-containing mordenite at temperature from 500 to 600°C. The invention also relates to a method of producing aliphatic carboxylic acid containing (n+1) carbon atoms, where n denotes an integer of up to 6, and/or an ether derivative thereof, which involves bringing the aliphatic alcohol containing n carbon atoms and/or reactive derivative thereof, selected from dialkyl ether, ester of alcohol and alkyl halide, into contact with carbon monoxide in the presence of said catalyst.

EFFECT: improved selectivity with respect to carbonylation products.

22 cl, 2 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acetic acid comprising the following steps: (a) carbonylation of methanol and/or reactive derivative thereof with carbon monoxide in a first reaction zone containing a liquid reaction mixture which contains a carbonylation catalyst and a promoter metal for the carbonylation catalyst, methyl iodide, methyl acetate, acetic acid and optionally water, where the liquid reaction mixture contains, in equilibrium, at least a first soluble catalytic material with a promoter metal and a second soluble catalytic material with a promoter metal, wherein among the materials which are in equilibrium, the first catalytic material with a promoter metal is the least promoter active; (b) outputting from said first reaction zone the liquid reaction mixture together with dissolved and/or trapped carbon monoxide and other gases; (c) optionally passing said output liquid reaction mixture through one or more successive reaction zones for using up at least a portion of the dissolved and/or trapped carbon monoxide; (d) directing said liquid reaction mixture from step (b) and optional step (c) to one or more steps for separation through single equilibrium evaporation to obtain a vapour fraction which contains condensable components and a low-pressure exhaust gas, where the condensable components contain the obtained acetic acid, methyl iodide, methyl acetate and optionally water, and the low-pressure exhaust gas contains carbon monoxide and other gases which are dissolved and/or trapped by the output liquid reaction mixture; and a liquid fraction which contains the carbonylation catalyst, the promoter metal for the carbonylation catalyst and acetic acid as a solvent; (e) returning the liquid fraction from the step for separation through single equilibrium evaporation to the first reaction zone; (f) determining (I) concentration of the first catalytic material with a promoter metal and/or (II) the ratio of concentration of the first catalytic material with a promoter metal to concentration of the second catalytic material with a promoter metal which are in equilibrium with each other, contained in the liquid reaction mixture at any of steps (a) to (d) and/or contained in the liquid fraction at step (e); and (g) maintaining (I) and/or (II) lower than a predetermined value.

EFFECT: present invention enables to optimise the process of producing acetic acid through carbonylation of methanol and/or a reactive derivative by maintaining concentration of the first catalytic material and/or the ratio of concentration of the first to the second catalytic material lower than a value where the negative effect could have been on one or more of such parameters as rate of reaction, selectivity, stability or service life of the catalyst.

13 cl 1 dwg, 2 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to methods of removing acetaldehyde from a mixture of methyl acetate, methanol and acetaldehyde, one of which involves: (a) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (b) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (c) returning as reflux a portion of the vapour stream which is output from the top of the column into the rectification column; and (d) removing a stream of the bottom residue poor in acetaldehyde from the rectification column, where temperature of the vapour stream from the top of the column ranges from 85°C to 115°C. The invention also relates to a method of producing acetic acid, involving: (a) cleaning the mixture of methyl acetate, methanol and acetaldehyde with removal of acetaldehyde by: (i) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (ii) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream which is output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (iii) returning as reflux a portion of the vapour stream output from the top of the column into the rectification column; and (iv) removing a stream of the bottom residue poor in acetaldehyde from the rectification column; (b) feeding the cleaned stream of bottom residue into the reaction mixture for carbonylation together with carbon oxide, where the reaction mixture for carbonylation contains water, a catalyst selected from rhodium catalysts, iridium catalysts or mixtures thereof, a promoter from methyl iodide and acetic acid; and (c) extracting acetic acid from the carbonylation mixture, where temperature of the stream which is output from the top of the column ranges from 85°C to 115°C.

EFFECT: improved methods.

15 cl, 8 dwg, 6 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of transferring heat to a liquid mixture containing at least one (meth)acrylic monomer selected from a group comprising acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, methyl acrylate, methyl methacrylate, n-butyl acrylate, isobutyl acrylate, isobutyl methacrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, through an indirect heat exchanger on whose primary side a fluid heat carrier flows and on whose secondary side simultaneously flows said liquid mixture containing at least one (meth)acrylic monomer, wherein the liquid mixture containing at least one (meth)acrylic monomer, in order to reduce contamination, additionally contains at least one active compound other than (meth)acrylic monomers which is selected from a group consisting of tertiary amines, salts formed from a tertiary amine and a Bransted acid, and quaternary ammonium compounds, under the condition that none of the tertiary and quaternary nitrogen atoms in the at least one active compound bears a phenyl group but at least some of said tertiary and quaternary nitrogen atoms bear at least one alkyl group.

EFFECT: improved method.

15 cl, 16 ex

FIELD: chemistry.

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

EFFECT: improved method for distillation purification of polymerisable compounds.

6 cl, 1 dwg, 2 ex

FIELD: chemistry.

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

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

5 cl, 2 ex

FIELD: chemistry.

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

EFFECT: less susceptibility of acrylic acid or methacrylic acid to polymerisation during fractional separation of liquid II.

8 cl, 3 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: method of carbonylating an alcohol and/or reactive derivative thereof includes the following steps: (a) feeding one or more streams of starting materials into a reaction zone, where at least one stream of starting materials of the reaction zone includes an alcohol and/or reactive derivative thereof and at least one stream of starting materials of the reaction zone includes carbon monoxide; (b) maintaining temperature and pressure in the reaction zone which is sufficient to enable flow of an exothermic carbonylation reaction to obtain a carboxylic acid and/or carboxylic acid anhydride; (c) removal from the reaction zone of one or more product streams containing carboxylic acid and/or carboxylic acid anhydride; (d) transferring heat contained in at least part of one or more product streams to a first heat-exchange stream. Heat is transferred from a second heat-exchange stream to the stream of starting materials of the reaction zone at step (a) before directing said stream of initial materials of the reaction zone into the reaction zone where temperature of the second heat-exchange stream before heat transfer is lower than the temperature of one or more product streams. That way, heat coming from the second heat-exchange stream can be transferred to the first heat-exchange stream.

EFFECT: low heat loss and high efficiency of the process.

17 cl, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a solid sodium diformate composition, having forming acid content of at least 35% of the total weight of the sodium diformate composition, in which aqueous solution (E) is prepared at high temperature, said solution containing sodium formate and formic acid in molar ratio HCOOH:HCOONa higher than 1.5:1, and having molar ratio HCOOH:H2O of at least 1.1:1, said aqueous solution (E) is crystallised to obtain a solid phase and a mother solution, and the solid phase is separated from the mother solution, where (i) the mother solution is completely or partially fed into a distillation apparatus; (ii) the mother solution in the distillation apparatus is mixed with a sodium-containing base to obtain a mixture (B) which contains sodium formate and formic acid; (iii) the mixture (B) obtained at step (ii) is mixed with formic acid to obtain aqueous solution (E); or the mixture (B) obtained at step (ii) is removed from the distillation apparatus and taken for crystallisation, or, at the crystallisation step, mixed with formic acid to obtain an aqueous solution; and (iv) excess water is primarily removed by tapping from the distillation apparatus; the invention also relates to use of the solid sodium formate composition obtained using the disclosed method as an animal feed additive, particularly feed for non-ruminants, especially pigs and/or birds.

EFFECT: improved properties of the composition.

29 cl, 3 dwg, 1 tbl, 4 ex

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of producing acrylic acid via gas-phase catalytic oxidation of propylene and/or acrolein, and specially to a step for extracting acrylic acid from aqueous solution formed during absorption of gaseous oxidation products with water. The method of extracting acrylic acid involves using a solvent to extract acrylic acid from its aqueous solution which contains acetic acid, formaldehyde, high-boiling impurities, distillation of the extract which contains acrylic acid, solvent, water and acetic acid, while feeding the solvent in form of condensate at low pressure with azeotropic distillation of water and solvent and extraction of the residue which contains acrylic acid and acetic acid, followed by distillation of the extracted residue which contains acrylic and acetic acid, while feeding condensate at low pressure in the presence of a polymerisation inhibitor with extraction of the desired acrylic acid and distillation of the distillate which contains acetic acid and acrylic acid, where distillation of the extract, which contains acrylic acid, solvent, water and acetic acid, is carried out while additionally feeding water to the step for distillation of the extracted residue which contains acrylic and acetic acid. The polymerisation inhibitor used is in form of an aqueous and the distilled distillate containing acetic acid and acrylic acid undergoes distillation at low pressure in the presence of a polymerisation inhibitor with extraction of acrylic acid and returning it to the step for distillation of the extracted residue containing acrylic and acetic acid.

EFFECT: high purity of the extracted acrylic acid and prevention of polymerisation of acrylic acid in equipment.

3 ex, 1 dwg

FIELD: chemistry.

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

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

20 cl, 1 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to rectification separation of fluid containing acrylic acid whereat said fluid is fed through loading point to rectification column and mass flow is discharged there through at discharge point arranged above said loading point. Content of acrylic acid in said mass flow in terms of mass flow weight makes ≥90 % by weight and exceeds acrylic acid content in fluid in rectification column zone located at least two theoretical separation stages above said loading point. Content of di-acrylic acid in reflux in terms of reflux weight in at least partial zones, makes ≥550 ppm by weight. Note here that said content of di-acrylic acid in reflux is defined from the presence of Bronsted acid with pKa ≤ 16 in fluid containing acrylic acid, or at least one Bronsted base with pKb ≤ 10, and/or adding to reflux of at least one compound from the group comprising aforesaid Bronsted acid with pKa ≤ 16, Bronsted base with pKa ≤ 10, di-acrylic acid and acrylic acid that contains acrylic acid. That is, mass flow enriched with acrylic acid is discharged from rectification column at the point above loading point while radial polymerisation is inhibited by di-acrylic acid at rectification column top.

EFFECT: efficient separation of fluids.

23 cl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to methods of removing acetaldehyde from a mixture of methyl acetate, methanol and acetaldehyde, one of which involves: (a) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (b) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (c) returning as reflux a portion of the vapour stream which is output from the top of the column into the rectification column; and (d) removing a stream of the bottom residue poor in acetaldehyde from the rectification column, where temperature of the vapour stream from the top of the column ranges from 85°C to 115°C. The invention also relates to a method of producing acetic acid, involving: (a) cleaning the mixture of methyl acetate, methanol and acetaldehyde with removal of acetaldehyde by: (i) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (ii) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream which is output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (iii) returning as reflux a portion of the vapour stream output from the top of the column into the rectification column; and (iv) removing a stream of the bottom residue poor in acetaldehyde from the rectification column; (b) feeding the cleaned stream of bottom residue into the reaction mixture for carbonylation together with carbon oxide, where the reaction mixture for carbonylation contains water, a catalyst selected from rhodium catalysts, iridium catalysts or mixtures thereof, a promoter from methyl iodide and acetic acid; and (c) extracting acetic acid from the carbonylation mixture, where temperature of the stream which is output from the top of the column ranges from 85°C to 115°C.

EFFECT: improved methods.

15 cl, 8 dwg, 6 tbl, 16 ex

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