Removing hydrocarbon impurities from acetic acid production intermediate product

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of removing hydrocarbon impurities from an intermediate product of production of acetic acid, which includes extracting the intermediate product with a hydrocarbon extracting agent to form a light phase containing the hydrocarbon impurity and the extracting agent, and a heavy phase containing acetic acid, where the intermediate product contains methyl iodide, acetic acid, methyl acetate and the hydrocarbon impurity. The invention also relates to a method of producing acetic acid, which includes a) reacting methanol and carbon monoxide in the presence of a carbonylation catalyst, a catalyst stabiliser, methyl iodide, water and methyl acetate to obtain an acetic acid stream containing a hydrocarbon impurity; b) dividing, by flash evaporation, the acetic acid stream into a vapour stream containing acetic acid, water, methanol, methyl acetate, methyl iodide and the hydrocarbon impurity, and a liquid stream containing the catalyst and the catalyst stabiliser; c) dividing the vapour stream from step b) by distillation into a product stream containing acetic acid and water, and an overhead product containing methyl iodide, water, methyl acetate, acetic acid and the hydrocarbon impurity; d) condensing the overhead product from step c) to form a light aqueous phase containing water and acetic acid, methyl acetate and a heavy organic phase containing methyl iodide, acetic acid, water and the hydrocarbon impurity; e) distilling the heavy organic phase from step d) into a vapour stream containing methyl iodide, and a lower stream containing acetic acid, methyl iodide, water and the hydrocarbon impurity; and f) extracting the lower stream from step e) with a hydrocarbon extracting agent and forming a light phase containing the hydrocarbon impurity and the extracting agent, and a heavy phase containing methyl iodide, water and acetic acid.

EFFECT: improved method of removing hydrocarbon impurities from an acetic acid production intermediate product.

13 cl, 6 ex

 

The technical FIELD TO WHICH the INVENTION RELATES.

The invention relates to the production of acetic acid. More specifically, the invention relates to a method of removing hydrocarbon impurities from intermediate production of acetic acid.

PRIOR art

Acetic acid is produced in industry by carbonyliron methanol. Before 1970 acetic acid was obtained using a cobalt catalyst. In 1970 Monsanto (Monsanto) was developed as a catalyst for carbonylated rhodium. The rhodium catalyst is much more active than cobalt catalyst and allows a lower pressure and the reaction temperature. Most importantly, the rhodium catalyst provides high selectivity for acetic acid.

One of the problems associated with the production method Monsanto, is that for hydrogen in the reactor by the reaction of conversion of water gas (CO+H2Oh⇄CO2+H2) you need a large amount of water (about 14%). Water and hydrogen are required for interaction with the besieged Rh(III) and inactive [Rh4(CO2] for regenerating the active Rh(I) catalyst. Such a large amount of water increases the amount of hydrogen iodide, which is very aggressive and leads to technological problems. In addition, the removal of Bo is isogo amount of water from the product acetic acid is expensive.

In the late 70s Celanese (Celanese) modified the carbonyl process by adding at carbonyliron in the reaction mixture a salt of lithium iodide. Salt is lithium iodide increases the stability of the catalyst minimize side reactions that cause the inactive species Rh(III), and therefore the quantity of water required is reduced. However, the high concentration of salt, lithium iodide, promotiom corrosion of reaction vessels under stress cracking. Furthermore, the use of salts itestosterone acid, iodides, increases pollution iodides product, acetic acid.

In the early '90s Millennium Petrochemicals has developed a new rhodium catalytic system for carbonylation, which does not use iodide salt. The catalytic system used as stabilizer catalyst pentavalent oxide VA group, such as triphenylphosphine oxide. The catalytic system Millenniun not only reduces the amount of water, but also increases the rate of carbonylation and the yield of acetic acid. Cm. U.S. patent No. 5817869.

One of the important problems of the industry is to remove from the reaction carbonylation of methanol impurities hydrocarbons, such as alkanes and aromatic hydrocarbons. The removal of alkanes of acetic acid are known. For example, the method of removing alcantarillado in U.S. patent No. 4102922. According to the patent '922 moving flow of the heavy phase, which contains methyl iodide, acetic acid, water and alkanes, is fed into the distillation column alkane with the temperature of the top of the column of about 75°C and the temperature in the lower part of the column of about 142°C. the Temperature in the lower part of the column support is significantly higher than in the upper part, in order to minimize the loss of methyl iodide in the lower stream. Top zipper distillation alkane containing mainly methyl iodide, return to the reaction zone. The bottom stream containing about 50% acetic acid and about 40% of the alkane, is removed from the system as waste. The problem with this way is that the high temperature in the lower part of the column of the low-boiling alkanes such as 2-methylpentane, proceed in the upper stream of methyl iodide. The result of the formation of low-boiling alkanes in the reaction system in the form of the upper stream of methyl iodide is their return to the carbonylation reaction.

There is a need for a new method of removal of alkanes and other hydrocarbon impurities from the production process of acetic acid. Ideally, this way you can effectively remove impurities as high-boiling and low-boiling hydrocarbons from the production process of acetic acid.

The INVENTION

The invention of t is made by a method of removing hydrocarbon impurities from intermediate production of acetic acid. The method involves extraction of the intermediate agent, extracting the hydrocarbons with the formation of the light phase containing an admixture of hydrocarbons and extracting agent, and a heavy phase containing acetic acid. Preferably make the extraction of the bottom stream of the distillation of alkanes, which contains methyl iodide, acetic acid and mixtures of hydrocarbons.

DETAILED description of the INVENTION

Admixture of hydrocarbons are formed as a result of adverse reactions carbonylation of methanol. Examples of impurities hydrocarbons include alkanes, alkenes and aromatic hydrocarbons. Impurities alkanes commonly used in carbonyliron methanol, represent3-C12-alkanes, including propane, butane, pentane, 2-methylbutane, 2,3-Dimethylbutane, 2-methylpentane, 3-methylpentane, hexane, octane, decane, cyclohexane, like hydrocarbons and their mixtures. Usually occurring alkenes include propylene, butene, octene, such hydrocarbons and their mixtures. A naturally occurring aromatic hydrocarbons include benzene, para-propylbenzoyl, toluene, xylene, like hydrocarbons and mixtures thereof.

The carbonylation reaction is carried out in the presence of a carbonylation catalyst and the catalyst stabilizer. Suitable carbonylation catalysts include catalysts known in the industrial Pro is svojstva acetic acid. Examples of suitable carbonylation catalysts include rhodium catalysts and iridium catalysts.

Suitable rhodium catalysts indicated, for example, in U.S. patent No. 5817869. Suitable rhodium catalysts include metal rhodium and compounds of rhodium. Preferably compounds of rhodium selected from the group consisting of rhodium salts, rhodium oxides, rhodium acetate, radiogenicity compounds, coordination compounds of rhodium, of such compounds and their mixtures. More preferred compounds of rhodium selected from the group consisting of Rh2(CO)4I2Rh2(CO)4Br2Rh2(CO)4Cl2Rh(CH3CO2)2Rh(CH3CO2)3, [H]Rh(CO)2I2such compounds and their mixtures. The most preferred compounds of rhodium selected from the group consisting of [H]Rh(CO2)2Rh(CH3CO2)2such compounds and their mixtures.

Suitable iridium catalysts indicated, for example, in U.S. patent No. 5932764. Suitable iridium catalysts include metallic iridium and iridium compounds. Examples of suitable iridium compounds include IrCl3, IrI3, IrBr3, [Ir(CO)2I]2, [Ir(CO)2Cl]2, [Ir(CO)2Br]2, [Ir(CO)4I2]-H+, [Ir(CO)2Br2]-]H+, [Ir(CO)2I2/sub> ]-H+, [Ir(CH3)I3(CO)2]-H+Ir4(CO)12, IrCl3·4H2O, IrBr3·4H2O Ir3(CO)12Ir2O3, IrO2, Ir(acac)(CO)2, Ir(acac)3Ir(OAc)3, [Ir3O(OAc)6(H2O)3][OAc] and H2[IrCl6]. Preferably the iridium compounds are selected from the group consisting of acetates, oxalates, acetoacetate, of such compounds and their mixtures. More preferred compounds of iridium, representing the acetates.

The iridium catalyst is preferably used with socialization. Preferred socializaton include metals and metal compounds selected from the group consisting of osmium, rhenium, ruthenium, cadmium, mercury, zinc, gallium, indium and tungsten, their compounds, such compounds and their mixtures. More preferred localizator selected from the group consisting of compounds of ruthenium and osmium compounds. The most preferred socializaton are compounds of ruthenium. Preferably socializaton are acetates.

Preferably the reaction is carried out in the presence of a catalyst stabilizer. Suitable stabilizers catalyst include stabilizers known in the industry. Generally there are two types of stabilizers catalyst. The first type of stabilizer can produce the RA is a salt of a metal iodide, such as lithium iodide. The second type of catalyst stabilizer is mesolevel stabilizer. Preferred naselenie stabilizers are oxides of pentavalent elements of the VA group. Cm. U.S. patent No. 5817869. The preferred phosphine oxides. The preferred oxides of triphenylphosphine.

The carbonylation reaction is preferably carried out in the presence of water. Preferably the concentration of water is from about 2 wt.% to about 14 wt.% calculated on the total weight of the reaction mixture. More preferably the concentration of water is from about 2 wt.% up to about 10 wt.%. Most preferably the concentration of water equal to from about 4 wt.% to about 8 wt.%.

The reaction is preferably carried out in the presence of acetate. The acetate can be formed in situ. If desired, the acetate can be added to the reaction mixture as a starting material. Preferably the concentration of acetate is from about 2 wt.% up to about 20 wt.% calculated on the total weight of the reaction mixture. More preferably, the concentration of acetate is from about 2 wt.% to about 16 wt.%. Most preferably, the concentration of acetate is from about 2 wt.% to about 8 wt.%. Alternatively, in the carbonylation reaction may be used a mixture of IU is racette and methanol flows from a by-product of the hydrolysis/methanolysis of polyvinyl acetate.

The reaction is carried out in the presence of methyl iodide. Methyl iodide is a promoter catalyst. Preferably, the concentration of methyl iodide is from about 0.6 wt.% to about 36 wt.% calculated on the total weight of the reaction mixture. More preferably, the concentration of methyl iodide is from about 4 wt.% to about 24 wt.%. Most preferably, the concentration of methyl iodide is from about 6 wt.% up to about 20 wt.%. Alternatively, methyl iodide can be generated in the carbonylation reactor by adding hydrogen iodide (HI).

In the reactor may also be injected hydrogen. The addition of hydrogen can improve the effectiveness of carbonylation. Preferably the concentration of hydrogen in the reactor is from about 0.1 mol.% to about 5 mol.% in the calculation of the carbon monoxide. More preferably, the concentration of hydrogen in the reactor is from about 0.3 mol.% to about 3 mol.% from carbon monoxide.

Methanol and carbon monoxide is fed into the carbonylation reactor. Supply of methanol in a carbonylation reactor can go from installation synthesis gas is methanol or from any other source. Methanol does not react directly with carbon monoxide with the formation of acetic acid. He turns into methyl iodide as a result of interaction with Pris is stoysin in the reactor, hydrogen iodide and then reacts with carbon monoxide and water with the formation of acetic acid and the regeneration of hydrogen iodide. Carbon monoxide not only becomes part of the molecule of acetic acid, but also plays an important role in the formation and stability of the active catalyst.

The carbonylation reaction is preferably carried out at a temperature in the range of from about 150°to about 250°C. More preferably the reaction is carried out at a temperature in the range of from about 150°to about 200°C. the carbonylation Reaction is preferably performed under a pressure in the range of from about 200 psi to about 2000 psi. More preferably the reaction is carried out under pressure in the range of from about 300 psi to about 500 psi.

The flow of the product acetic acid away from the reactor and share instant evaporation of the liquid fraction containing the catalyst and the catalyst stabilizer, and steam fraction containing the product, acetic acid, reagents, water, methyl iodide and impurities formed during the carbonylation reaction, including alkanes, alkenes and aromatic hydrocarbons. The liquid fraction is returned to the carbonylation reactor. Steam fraction is then fed to the distillation column.

Distillation column, the so-called "distillation light tails" separates the head wrap, containing methyl iodide, water, methanol, methyl acetate and mixtures of hydrocarbons from the stream, steriade what about acetic acid, a small amount of water and a little heavy impurities such as propionic acid. The flow of acetic acid can be directed column-dryer to remove water and then subjected to distillation, the so-called "distillation of heavy tails" to remove heavy impurities.

Thread the top of the shoulder strap from the distillation of light tails typically contains from about 60 wt.% to about 90 wt.% iodide, bromide, and from about 5 wt.% to about 15 wt.% methyl acetate, from about 1 wt.% up to about 10 wt.% acetic acid, 1 wt.% or less of water, from about 1 wt.% up to about 10 wt.% hydrocarbon impurities and about 2 wt.% or less of impurities of aldehydes, calculated on the total weight of the upper shoulder strap.

Thread the top of the shoulder strap condense and are separated in the decanter on the light aqueous phase and a heavy organic phase. Heavy organic phase contains predominantly methyl iodide (over 50%) and mixtures of hydrocarbons. Easy aqueous phase contains predominantly water (over 50%), acetic acid and methyl acetate. The aqueous phase is usually returned to the reactor or distillation light tails.

At least part of the heavy organic phase is distilled to a vapor stream containing mainly methyl iodide (more than 50% of methyl iodide from the heavy organic phase) and a bottom stream containing mainly acetic acid is, methyl acetate, methyl iodide and mixtures of hydrocarbons (more than 50% of each component of the heavy organic phase). This distillation in the industry is a so-called bulk alkanes. The temperature of the upper shoulder strap the pickup alkanes preferably below about 75°C., so that the flow of vapor does not leave a significant amount of hydrocarbon impurities. More preferably, the temperature of the upper shoulder strap the pickup alkanes in the range of approximately 43°C (boiling point of methyl iodide) to about 75°C. Most preferably the temperature of the upper shoulder strap the pickup alkanes is in the range from about 43° to about 60°C. a Particularly preferred temperature of the upper shoulder strap the pickup alkanes is in the range from about 43°to about 45°C. the closer the temperature of the upper shoulder strap the pickup alkanes to the boiling point of methyl iodide, the less amount of impurities hydrocarbons located in the steam flow. Steam flow is returned to the carbonylation reaction. Reducing the temperature of the upper shoulder strap the pickup alkanes, although reduces hydrocarbon impurities in the steam flow, leads to a higher concentration of methyl iodide in the lower stream. In accordance with normal industry practice, the lower thread is considered waste. Thus, drop felicienne number of iodide of methyl, expensive substances.

The method of the invention includes the extraction of hydrocarbon impurities from any of the above intermediates or threads. Preferably the extraction is carried out from the lower flow acceleration alkanes. The extraction was carried out by mixing the lower flow acceleration alkanes with extracting hydrocarbons agent and the formation of a light phase containing the extracting agent and admixture of hydrocarbons, and heavy phase, which contains methyl iodide and acetic acid. Preferably the heavy phase contains less than 50% of the hydrocarbon impurities lower flow acceleration alkanes. More preferably, the heavy phase is essentially no admixture of hydrocarbons. The heavy phase can be returned to the rectification of alkanes or in the carbonylation reaction.

Agent, extracting hydrocarbons, preferably selected from from From9to C20aromatic or paraffinic hydrocarbons. Extracting agent can be a mixture of water from C9to C20aromatic or paraffinic hydrocarbons. Preferably water is used in an amount of from about 5 vol.% up to about 50 vol.% from the volume of agent, extracting hydrocarbons. The presence of water causes a greater transition of acetic acid in the heavy phase, which, as indicated above, may be recyclebank. Light phase which can be removed or treated and returned extracting agent.

Preferably the extraction is subjected to from about 5% to about 100% of the lower phase of acceleration of alkanes. More preferably the extraction is subjected to from about 50% to about 100% of the lower phase of acceleration of alkanes.

Preferably the ratio of the extracting agent to the lower flow acceleration alkanes is in the range of from 25/75 to 75/25 (vol./vol.). If desired, the lower flow acceleration alkanes can be preextraction more than once.

The following examples are only illustrative. Experts in the art may find many variations within the spirit of the invention and within the scope of the claims.

EXAMPLE 1

Extraction of the lower flow acceleration alkane by pentadecanol

Simulated lower flow acceleration alkanes (5 parts by volume, containing 15.0 wt.% iodide, bromide, 14.3 wt.% octane and to 70.7 wt.% acetic acid) mixed with pentadecanol (5 parts by volume) in a vial at room temperature (25°C). There is a separation of phases. The ratio of light phase heavy phase is equal to 1.76 by weight. Light phase and heavy phase is analyzed by infrared measurements of samples ATR (attenuated full reflectance). The light phase contains of 12.9 wt.% octane, 4.1 wt.% iodide, bromide, 17.3 wt.% acetic acid and 65.7 wt.% pentadecane. The heavy phase contains at 16.9 wt.% iodide, bromide, of 82.5 wt.% acetic acid and &t; 1 wt.% octane.

EXAMPLE 2

Extraction of the lower flow acceleration alkanes by pentadecanol

Example 1 is repeated, but the volume ratio of pentadecane to simulated flow acceleration alkanes is 2.0. There is a separation of phases. The ratio of light phase heavy phase is 4,11 by weight. The light phase contains about 7.2 wt.% octane, 3.6 wt.% iodide, bromide, or 15.7 wt.% acetic acid and 73.5 wt.% pentadecane. The heavy phase contains 16.5 wt.% iodide, bromide, 87,2 wt.% acetic acid and <1 wt.% octane.

EXAMPLE 3

Extraction of the lower flow acceleration alkanes by pentadecanol

Example 1 is repeated, but the volume ratio of pentadecane to simulated flow acceleration alkanes is 3.0. There is a separation of phases. The ratio of light phase heavy phase is 7,19 by weight. The light phase contains a 5.1 wt.% octane, 2.2 wt.% iodide, bromide, 14.7 wt.% acetic acid and 78,0 wt.% pentadecane. The heavy phase contains of 22.8 wt.% iodide, bromide, 76,2 wt.% acetic acid and <1 wt.% octane.

EXAMPLE 4

Extraction of the lower flow acceleration alkanes by dodecanol

Simulated lower flow acceleration alkanes (3 parts by volume, containing 17.5 wt.% iodide, bromide, 5.9 wt.% Dean, of 6.8 wt.% hexane and by 89.8 wt.% acetic acid) are mixed in a bottle with dodecanol (3 parts by volume) at room temperature (25°C). There is a separation of phases. Otnosheniia phase to the hard phase is 2,12 by weight. Light phase and heavy phase is analyzed by measuring infrared radiation. The light phase contains 3.8 wt.% Dean, 4.3 wt.% hexane, 5.1 wt.% iodide, bromide, and 26.1 wt.% acetic acid and to 60.6 wt.% dodecane. The heavy phase contains 2.3 wt. % decane, 2,8 wt.% hexane, a 21.1 wt.% iodide, bromide and of 73.8 wt.% acetic acid.

EXAMPLE 5

Extraction of the lower flow acceleration alkanes by pentadecanol in the presence of water

Simulated lower flow acceleration alkanes (5 parts by volume) of the composition as described in example 1, is mixed with pentadecanol (13 parts by volume) and water (2 parts by volume) in a vial at room temperature (25°). There is a separation of phases. The ratio of light phase heavy phase is 1,99 by weight. Light phase and heavy phase is analyzed by measuring infrared radiation. The light phase contains a 3.3 wt.% octane of 6.4 wt.% iodide, bromide, 4.7 wt.% acetic acid and 85.6 wt.% pentadecane. The heavy phase contains 6.9 wt.% octane, 1.3 wt.% iodide, bromide, of 56.7 wt.% acetic acid and to 35.0 wt.% water.

EXAMPLE 6

Extraction of the lower flow acceleration alkanes by pentadecanol in the presence of water

Example 5 is repeated, but imitated the lower flow acceleration alkanes mixed with pentadecanol (10 parts by volume) and H2About 5 parts by volume) in a vial at room temperature. There is a separation of phases. The ratio of the light phase, the hard phase is equal to 1.04 million by weight. Light and heavy phase is analyzed by measuring infrared radiation. The light phase contains 6.2 wt.% octane, 8.2 wt.% iodide, bromide, 1.0 wt.% acetic acid and to 84.6 wt.% pentadecane. The heavy phase contains 0.6 wt.% iodide, bromide, 42,1 wt.% acetic acid and 57.3 wt.% water.

1. Method of removing hydrocarbon impurities from intermediate production of acetic acid, including extraction of intermediate agent, extracting the hydrocarbons with the formation of the light phase containing an admixture of hydrocarbons and extracting agent, and a heavy phase containing acetic acid, where the semi-product contains methyl iodide, acetic acid, methyl acetate and mixture of hydrocarbons.

2. The method according to claim 1, where the mixture of hydrocarbons selected from the group consisting of alkanes, alkenes, aromatic hydrocarbons and mixtures thereof.

3. The method according to claim 2, where the alkane is a C3-C12alkane.

4. The method according to claim 1, where the intermediate is represented by the lower flow acceleration alkanes.

5. The method according to claim 1, where extracting agent represents a C9to C20aromatic or paraffinic hydrocarbon.

6. The method according to claim 1, comprising adding water extraction.

7. Method for the production of acetic acid, including:
a) interaction of methanol and carbon monoxide in the presence of a carbonylation catalyst,stabilizer, catalyst, iodide, bromide, water and methyl acetate with receiving a stream of acetic acid containing an admixture of hydrocarbons;
b) separation of instantaneous evaporation of a stream of acetic acid on a steam stream containing acetic acid, water, methanol, methyl acetate, methyl iodide and the mixture of hydrocarbons and a liquid stream containing the catalyst and the catalyst stabilizer;
c) separation of the steam flow from step b) by distillation in a stream of product containing acetic acid and water, and the top zipper containing methyl iodide, water, methyl acetate, acetic acid and mixture of hydrocarbons;
d) condensation of the upper shoulder strap with stage c) with the formation of the light aqueous phase containing water and acetic acid, methyl acetate, and heavy organic phase containing methyl iodide, acetic acid, water and an admixture of hydrocarbons; and
e) distillation of the heavy, organic phase from step d) to a steam stream containing methyl iodide, and the bottom stream containing acetic acid, methyl iodide, water and mixture of hydrocarbons; and
(f) extraction of the bottom stream from step (e) of the hydrocarbon extracting agent and the formation of the light phase containing an admixture of hydrocarbons and extracting agent, and a heavy phase containing methyl iodide, water and acetic acid.

8. The method according to claim 7, which includes the return of the heavy phase from step (f) on the stud is th (a).

9. The method according to claim 7, where the catalyst is a rhodium catalyst.

10. The method according to claim 7, where the stabilizer of the catalyst is an oxide of triphenylphosphine.

11. The method according to claim 7, where the concentration of water at the stage a) is in the range from 2 wt.% up to 10 wt.% in the calculation of the reaction mixture.

12. The method according to claim 7, where the mixture of hydrocarbons selected from the group consisting of alkanes, alkenes, aromatic hydrocarbons and mixtures thereof.

13. The method according to claim 7, where the agent, extracting hydrocarbons represents a C9to C20aromatic or paraffinic hydrocarbons.



 

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15 cl, 11 dwg, 3 ex

FIELD: chemistry.

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

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

15 cl, 4 dwg, 2 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to bioengineering of food products and can be used in processing fermentation solutions to obtain lactic acid. The method of extracting lactic acid from fermentation solutions involves extracting lactic acid with a salt of a quaternary ammonium base in a diluenet and re-extracting the acid, wherein extraction is carried out with a salt of a quaternary ammonium base in sulphate form [(R4N)2SO4], where R is an alkyl or aryl radical, in the presence of p-tertiary alkylphenols in molar ratio of (R4N)2SO4 to p-tertiary alkylphenols of 1:2, at solution pH 5.0-7.0; the acid is re-extracted with sodium hydroxide solutions and the extractant is regenerated via treatment with a stoichiometric amount of sulphuric acid.

EFFECT: high degree of extraction of lactic acid from fermentation solutions and preventing the chloride ion from falling into the aqueous phase after extraction.

4 cl, 5 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to bioengineering of food products and can be used in processing fermentation solutions to obtain lactic acid. The method of extracting lactic acid from fermentation solutions involves extracting lactic acid with a salt of a quaternary ammonium base in a diluenet and re-extracting the acid, wherein extraction is carried out with a salt of a quaternary ammonium base in sulphate form [(R4N)2SO4], where R is an alkyl or aryl radical, in the presence of p-tertiary alkylphenols in molar ratio of (R4N)2SO4 to p-tertiary alkylphenols of 1:2, at solution pH 5.0-7.0; the acid is re-extracted with sodium hydroxide solutions and the extractant is regenerated via treatment with a stoichiometric amount of sulphuric acid.

EFFECT: high degree of extraction of lactic acid from fermentation solutions and preventing the chloride ion from falling into the aqueous phase after extraction.

4 cl, 5 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing pure methacrylic acid, which involves: a) gas-phase oxidation of a C4 compound to obtain a methacrylic acid-containing gas phase, b) condensing the methacrylic acid-containing gas phase to obtain an aqueous methacrylic acid solution, c) separating at least a portion of the methacrylic acid from the aqueous methacrylic acid solution to obtain at least one methacrylic acid-containing raw product, d) separating at least a portion of methacrylic acid from the at least one methacrylic acid-containing raw product by thermal separation to obtain pure methacrylic acid, wherein at step (d), methacrylic acid is separated from at least a portion of at least one methacrylic acid-containing raw product by fractionation, and wherein the pure methacrylic acid is collected through a side outlet used for the fractionation column, and the amount of pure methacrylic acid collected over a certain time interval ranges from 40% to 80% of the amount of the methacrylic acid-containing raw product fed into the fractionation column over the same time interval. The invention also relates to an apparatus for producing methacrylic acid using said method, the apparatus comprising: a1) a gas-phase oxidation unit, b1) an absorption unit, c1) a separation unit, and d1) a purification unit, wherein the purification unit has at least one distillation column, wherein the at least one distillation column has at least one side outlet for pure methacrylic acid. The invention also relates to a method of producing methacrylic esters, polymethacrylate, polymethacrylic esters, which includes a step for said production of pure methacrylic acid.

EFFECT: obtaining an end product with fewer by-products while simplifying the process.

32 cl, 3 tbl, 4 dwg, 6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for selective removal of propionic acid impurities from an acrylic acid stream. The method involves reacting an acrylic acid stream in the presence of a mixed metal oxide catalyst meant for removing propionic acid, wherein the mixed metal oxide catalyst contains a mixed metal oxide of the empirical formula AaMbNcXdZeOf, in which A is Mo, M is V, N is Te, X is Nb and Z is Pd, and O is oxygen in the oxide and in which if a=1, b=0.01-1.0, c=0.01-1.0, d=0.01-1.0, c=0-0.1 and f depends on the oxidation state of other elements.

EFFECT: improved method for selective removal of propionic acid impurities from an acrylic acid stream.

8 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of organic and petrochemical synthesis, specifically to the technology of producing isophthalic acid and a by-product - formic acid by liquid-phase oxidation with O2 gas in the medium of acetic acid in the presence of a Co and Mn salt catalyst at high temperature and pressure, followed by extraction of isophthalic acid and purification thereof by recrystallisation in a water-acetic solvent, extracting formic acid by distillation from the anhydrous acetic acid condensate formed when cooling the vapour-gas mixture removed from the reaction zone with spent air, where there is oxidation of m-diisopropylbenzene or m-ethyl-isopropylbenzene in three steps while raising temperature in steps in the range of (°C) 130-150; 140-160; 165-185°C, pressure (MPa) 0.3-0.6; 0.6-0.8; 0.9-1.2, overall concentration of the Co-Mn-Ni catalyst (ppm) 800 - 1060; 1000 - 1435; 1250 - 1744; and during air flow through the oxidation zone, concentration of CO/CO2 in the spent gas after each step is kept in the following ranges (vol. %): 0.16, 0.17, 0.18-0.25, 0.26 / 0.24, 0.25, 0.9-1.12, 1.19, 1.20, 1.21; 0.18, 0.2-0.3 / 0.9, 1.1-1.42; 0.2, 0.23-0.42 / 1.15, 1.2-1.6,1.8; 93.2-98.8% content of isophthalic acid in oxidation products extracted from the cooled oxidation product of step 3 is achieved, after which process isophthalic acid is purified by successive recrystallisation in CH3COOH while heating the suspension to 180-200°C, and then in H2O while heating the suspension to 200-230°C to obtain highly pure isophthalic acid, and formic acid formed during the oxidation process is extracted from the vapour-gas mixture from the oxidation reactor by cooling the vapour-gas mixture to 30-40°C, separating the formed condensate and treatment thereof with n-butyl acetate in ratio of acid to n-butyl acetate of 1:0.17; further, reaction water in form of its azeotropic mixture with n-butyl acetate and then formic acid and acetic acid are successively extracted from the obtained mixture by fractionation.

EFFECT: method enables to obtain to commercial products - aromatic isophthalic acid and aliphatic formic acid and increases output of the end products.

3 cl, 1 dwg, 2 tbl, 11 ex

FIELD: chemistry.

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

EFFECT: improved method.

21 cl, 6 ex

FIELD: chemistry.

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

EFFECT: method enables to prevent precipitation on equipment components and the resulting clogging, cleaning procedures and switching off.

16 cl, 8 ex

FIELD: chemistry.

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

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

44 cl, 2 dwg

FIELD: chemistry.

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

EFFECT: ensuring stable operation of a fluidised bed drier.

8 cl, 5 dwg, 1 tbl, 3 ex

FIELD: chemistry.

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

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

5 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to method of separating acrylic acid contained as main product, and glyoxal contained as by-product, in mixture of products of partial heterogeneously catalysed vapour-phase oxidation of acrylic acid precursor compound, which contains 3 carbon atoms, in which liquid phase P is obtained, which comprises acrylic acid to an extent of at least 70% of its weight, and, calculated for molar quantity of acrylic acid, contained therein, comprises at least 200 molar ppm of glyoxal, in which separation of glyoxal from acrylic acid is realised by crystallisation from liquid phase P.

EFFECT: method makes it possible to prevent undesirable polymerisation of acrylic acid.

25 cl

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