Method of separating mixture of benzoic and cinnamylic acid

FIELD: chemistry.

SUBSTANCE: sodium hydroxide solution is added to a technical mixture of benzoic and cinnamylic acid, obtaining a precipitate. Water is added to obtain a homogeneous solution. The obtained technical mixture of sodium salts of benzoic and cinnamylic acid with composition ranging from 2:1 to 1:2 and overall concentration ranging from 3 to 5 M is then mixed with sulphuric acid with concentration ranging from 3 to 5 M. Addition of sulphuric acid is stopped at pH of the medium between 8 and 9, and the precipitated complex of cinnamylic acid with its sodium salt is filtered from the reaction mixture, dissolved in excess amount of water to dissolve sodium salt of cinnamylic acid. Cinnamylic acid precipitates, and is further treated with sulphuric acid with concentration ranging from 3 to 5 M to pH between 1 and 2. The precipitated crystals of cinnamylic acid are separated; the reaction mixture remaining after separation of the complex is mixed with a solution of sulphuric acid with concentration ranging from 3 to 5 M until pH between 1 and 2. As a result, crystalline benzoic acid forms.

EFFECT: formation of complexes of carboxylic acids with their sodium salts for separating components of a mixture of carboxylic acids with similar chemical and physico-chemical properties.

2 ex

 

The invention relates to the production of organic acids used in chemical, food, pharmaceutical and other industries.

Known methods of separating mixtures: by recrystallization, namely, that the mixture of acids dissolve when heated and when cooled from the solution are precipitated by acids in the sequence of their solubility; known method of separation of organic acids by sublimation of one of them (Berlin PRODUCED the Technique of laboratory work in organic chemistry. Goskomizdat, 1952. Fisher L., Linstead R. Modern methods of experiment in organic chemistry. Goskomizdat, 1960).

The disadvantage of these methods is that they are applicable to organic acids, strongly differing in their ability to sublimation and solubility, while the acid with similar properties precipitate and sublime at the same time.

The applicant and the authors are unknown methods of separation of organic acids, based on the selective deposition of acids in the form of complexes with sodium salts of these acids.

The technical result of the proposed method is to ensure the formation of complexes of carboxylic acids and their sodium salts to separate components of a mixture of carboxylic acids with similar chemical and physico-chemical properties on the individual is the real substance.

The technical result is achieved in that in the method of separating a mixture of benzoic and cinnamic acids to the technical mixture of benzoic and cinnamic acids poured the sodium hydroxide solution to obtain a precipitate, and then poured water to obtain a homogeneous solution. The resulting mixture of sodium salts of benzoic and cinnamic acids composition of 2:1-1:2 when the total concentration of 3-5 M mixed with sulfuric acid at concentrations of 3-5 M sulfuric acid stop at pH 8-9, and dropped into the sediment complex cinnamic acid and its sodium salt is filtered and transferred to an excessive amount of water to dissolve the sodium salt of cinnamic acid. While cinnamic acid precipitates. The solution is further treated with sulfuric acid at concentrations of 3-5 M to pH 1-2, separating the precipitated precipitate crystals of cinnamic acid. The reaction mixture remaining after separation of the complex is mixed with sulfuric acid concentrations of 3-5 M to pH 1-2, resulting in sediment falls crystalline benzoic acid.

Experimentally it was found that in terms of the concentration of the mixture of sodium salts of carboxylic acids 3-5 M in the processing of sulfuric acid with a concentration of 3-5 M are formed complexes of carboxylic acids and their sodium salts precipitated in the form of a crystalline product. In the present case the e when adding sulfuric acid to precipitate falls complex cinnamic acid and its sodium salt, a salt of benzoic acid remains in solution and precipitates in the form of benzoic acid with subsequent mixing of the solution with sulfuric acid. This is ensured by the fact that cinnamic acid is weaker compared to benzoic (respectively pKa=4,43 and 4,20), and salt of cinnamic acid is a stronger base than with salt benzoic acid (respectively RKV=to 9.57 and 9,80). The time of precipitation of the complex cinnamic acid with its salt is fixed intervals of pH 9-8 corresponding to the hydrolysis of salts of cinnamic acid. Upon the occurrence of a specified time interval, the pH of prelivanje sulfuric acid stop and the product separated from the solution, passing the reaction mixture through a glass filter. The remaining solution is treated with excess of sulphuric acid for separation of crystals of benzoic acid. The complex of cinnamic acid with its salt decompose the excess water (cinnamic acid in water practically insoluble, and its sodium salt soluble) and treated with sulfuric acid for the full allocation of cinnamic acid.

Declare the parameters of the concentrations of the reagents contained in the formula are defined so that in solutions with different concentrations of reagents complexes of organic acid from its sodium salt is not formed.

Thus, the essential attribute of the Cove allows you to achieve the desired technical result.

Example 1. To a suspension of 10 g of a technical mixture of benzoic and cinnamic acids in the ratio 1:2 in 60 ml of water is poured dropwise a 40 percent solution of sodium hydroxide. After the first drops of alkali, the reaction mixture becomes homogeneous, and subsequent prilivnyi alkali falls rich sediment and the mass hardens. The solid mass is poured minimum amount of water to form a homogeneous solution, place in it a standard glass electrode to measure the pH of the reaction mixture was added dropwise and 3 M sulfuric acid. At pH 8 saliva, representing a complex of cinnamic acid and its salts composition of 1:1, which is separated, passing the reaction mass through a glass filter, and then dissolved in 100 ml of water (dissolves only salt, cinnamic acid is poorly soluble in water) and add sulfuric acid concentration of 3 M to pH 1. Fallen in sediment cinnamic acid is separated and dried by known methods. The reaction mixture remaining after separation of the complex is mixed with sulfuric acid concentration of 3 M to pH 1 appearing in the precipitate of benzoic acid is separated and dried by known methods.

Example 2. To a suspension of 10 g of a technical mixture of benzoic and cinnamic acid ratio of 2:1 in 60 ml of water is poured dropwise a 30% solution of sodium hydroxide. Subsequent operations are performed as in example 1, but the use of 5 M sulfuric acid. The result is similar to example 1.

The method of separating a mixture of benzoic and cinnamic acids, characterized by the fact that the technical mixture of benzoic and cinnamic acids poured the sodium hydroxide solution to obtain a precipitate, poured water to obtain a homogeneous solution, and then received a technical mixture of sodium salts of benzoic and cinnamic acids composition of 2:1-1:2 when the total concentration of 3-5 M mixed with sulfuric acid at concentrations of 3-5 M, sulfuric acid stop at pH 8-9, and dropped into the sediment complex cinnamic acid and its sodium salt is filtered off from the reaction mixture, dissolved in an excessive amount of water to dissolve the sodium salt of cinnamic acid, while cinnamic acid precipitates, and then further treated with sulfuric acid at concentrations of 3-5 M to pH 1-2, separating the precipitated precipitate crystals of cinnamic acid; the reaction mixture remaining after separation of the complex is mixed with sulfuric acid concentrations of 3-5 M to pH 1-2, resulting in sediment falls crystalline benzoic acid.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention concerns organic synthesis field, particularly method of obtaining benzoic acid (C6H5COOH, benzenecarboxylic acid) by catalytic oxidation of benzyl alcohol in hydrogen peroxide solution, as well as catalysts for method implementation, and method of obtaining catalysts. Catalysts of benzoic acid production is nanostructurised bifunctional metallocomplex catalyst acting as oxidation and interphase transport catalyst. It is a complex compound of the general formula Q3{PO4[W(O)(O2)2]4}, where: Q is quadruple ammonium cation [(R1)3N R2]+, where: R1 and R2 contain 8 to 24 carbon atoms. The invention concerns method of obtaining catalyst for benzoic acid production by dissolution of compounds containing phosphor and tungsten in hydrogen peroxide solution with added interphase transport catalyst compound, with phosphor-tungsten heteropolyacids of Keggin or Dawson structure are used as compounds containing phosphor and tungsten, dissolution is performed at the following mol ratio: hydrogen peroxide to tungsten [H2O2]/[W]=15-50, with further addition of quadruple ammonium cation - [(R1)3N R2]+ as interphase transport catalyst, where: R1 and R2 contain 8 to 24 carbon atoms. The invention also concerns method of obtaining benzoic acid by substrate oxidation in hydrogen peroxide in the presence of the catalyst described above.

EFFECT: increased efficiency of benzoic acid production process.

8 cl, 21 ex, 2 tbl, 1 dwg

The invention relates to an improved method of extraction of benzoic acid from the product of liquid-phase oxidation of toluene by distillation, which consists in the fact that the rectification is carried out at a column of the periodic operation at a pressure of 100 mm RT
The invention relates to a technology for production of benzoic acid, namely to obtain benzoic acid by hydrolysis of its methyl ester

The invention relates to the field of organic chemistry, specifically to a method for producing benzoic acid (Bq) or sodium benzoate (bn), the difference is that BC separated from the aqueous phase of oxidate obtained in the oxidation of toluene in the presence of water and sodium carbonate (KN), by evaporation of the aqueous phase with obtaining bn containing up to 20% ash, which is placed in a vertical reactor, for example type "Soxhlet", and the top serves aqueous organic solvent, for example ethanol, or acetone, or methyl ethyl ketone, containing 10 to 30% water, and carbon dioxide under pressure and bottom removed BC in the solvent

FIELD: chemistry.

SUBSTANCE: invention relates to a thermal separation method using fractional condensation of a product-gas mixture, obtained through heterogeneous catalysed partial oxidation of propene and/or propane in gaseous phase to acrylic acid, for separating at least one mass flow, concentrated with acrylic acid, from a product-gas mixture containing acrylic acid, which involves continuous static operation of at least one device for thermal separation, containing at least one effective separation chamber with a fractionation column which has mass-transfer trays as built-in separating elements, in which the product-gas mixture is loaded, containing acrylic acid as at least one mass flow, and from which at least one mass flow containing acrylic acid is unloaded under the condition that, the overall mass flow loaded into the effective separation chamber and obtained from combining separate mass flows loaded into the separating chamber, contains X wt % components distinct from acrylic acid, the mass flow which is unloaded from the effective separation chamber with the largest content of acrylic acid, contains Y wt % components distinct from acrylic acid, ratio X:Y is ≥5, effective separation chamber, except the loading and unloading place, is bordered by a solid phase and contains, besides the mass-exchange trays as built-in separating elements in the fractionation column, at least one circulating heat exchanger, and total volume of the chamber, filled with liquid phase, is ≥1 m3, wherein temperature of the liquid phase is at least partially ≥80°C, when the effective separation chamber is divided into n separate volume elements, wherein the highest and lowest temperature of liquid phase in a separate volume element differ by not more than 2°C, and the volume element in the effective separation chamber is solid, total dwell time ttotal.

≤20 h, where A = (Ti-To)/10°C, To= 100°C, Ti = arithmetic mean value of the highest and lowest temperature of the ith volume element in the liquid phase in °C, msi = total mass of acrylic acid in the volume of the liquid phase of the ith volume element, mi = total liquid phase mass unloaded from the ith volume element, and is the sum of all volume elements i, under the condition that, volume elements i with liquid phase mass mi and as volume elements with a dead zone are also not included in the sum of all volume elements i, as well as volume elements i, which do not contain liquid phase, and total amount of liquid phase contained in volume elements with a dead zone is not more than 5 wt % of the total amount of liquid phase contained in the effective separation chamber.

EFFECT: separation of mass flow concentrated with acrylic acid.

10 cl, 12 dwg, 2 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: proposal is given of a method of removing impurities from a water mixture or purified water mixture through extraction of the water mixture or purified water mixture using an extractive solvent in the extraction zone with formation of a stream of extract and a stream of raffinate and, optionally, separation of the extract stream and the solvent rich stream in the separation zone with formation of a stream of organic impurities with high boiling point and a stream of extractive solvent.

EFFECT: provision for extracting metallic catalyst in active form, reusable at the paraxylene recycling stage.

29 cl, 2 dwg, 1 tbl

FIELD: chemistry.

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

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

8 cl, 1 tbl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: method of separating multi-atom alcohols, for instance, neopentylglycol and sodium formiate, includes evaporation and cooling of reaction mixture, addition of organic solvent, crystallisation of sodium formiate, separation of sodium formiate from saturated solution of multi-atom alcohol, for instance, by filtration, and crystallisation of multi-atom alcohol. Reaction mixture is evaporated until two liquid layers are formed, which are separated into light phase - water-multi-atom alcohol and heavy phase -water-salt, separated water-salt fraction of solution is cooled until sodium formiate contained in it in form of cryslallohydrate is crystallised, sodium formiate crystals are separated, and remaining mother-solution is returned to process head, to evaporation stage, then separated light phase - water-multi-atom alcohol is additionally evaporated until 70% of contained in it sodium formiate is crystallised, then cooled to 25-30°C and subjected to processing with organic solvent from line of single-atom saturated alcohols, for instance, methane, for removal of remaining admixtures, with further crystallisation of multi-atom alcohol from remaining mother-solution.

EFFECT: reduction of amount of used organic solvent, elimination of high-temperature stage of extraction, preservation of yield of pure target products.

2 cl, 2 dwg, 1 ex

FIELD: chemistry.

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

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: chemistry.

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

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

19 cl, 1 dwg, 6 ex, 4 tbl

FIELD: chemical industry; methods of production of the purified crystalline terephthalic acid.

SUBSTANCE: the invention is pertaining to the improved method of production and separation of the crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid. The method provides for the following stages: (1) loading of (i) para- xylene, (ii) the water reactionary acetic-acidic medium containing the resolved in it components of the oxidation catalyst, and (iii) the gas containing oxygen fed under pressure in the first zone of oxidation, in which the liquid-phase exothermal oxidization of the para-xylene takes place, in which the temperature and the pressure inside the first being under pressure reactor of the oxidization are maintained at from 150°С up to 180°С and from 3.5 up to 13 absolute bars; (2) removal from the reactor upper part of the steam containing the evaporated reactionary acetic-acidic medium and the gas depleted by the oxygen including carbon dioxide, the inertial components and less than 9 volumetric percents of oxygen in terms of the non-condensable components of the steam; (3) removal from the lower part of the first reactor of the oxidized product including (i) the solid and dissolved terephthalic acid and (ii) the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (4) loading of (i) the oxidized product from the stage (3) and (ii) the gas containing oxygen, into the second being under pressure zone of the oxidation in which the liquid-phase exothermal oxidization of the products of the non-complete oxidization takes place; at that the temperature and the pressure in the second being under pressure reactor of the oxidization are maintained from 185°С up to 230°С and from 4.5 up to 18.3 absolute bar; (5) removal from the upper part of the second steam reactor containing the evaporated water reactionary acetic-acidic medium and gas depleted by the oxygen, including carbon dioxide, the inertial components and less, than 5 volumetric percents of oxygen in terms of the non-condensable components of the steam; (6) removal from the lower part of the second reactor of the second oxidized product including (i) the solid and dissolved terephthalic acid and the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (7) separation of the terephthalic acid from (ii) the water reactionary acetic-acidic medium of the stage (6) for production the terephthalic acid containing less than 900 mass ppm of 4- carboxybenzaldehyde and the p-toluene acid; (8) dissolution of the terephthalic acid gained at the stage (7) in the water for formation of the solution containing from 10 up to 35 mass % of the dissolved terephthalic acid containing less than 900 mass ppm of the 4- carboxybenzaldehyde and the p-toluene acid in respect to the mass of the present terephthalic acid at the temperature from 260°С up to 320°С and the pressure sufficient for maintaining the solution in the liquid phase and introduction of the solution in contact with hydrogen at presence of the catalytic agent of hydrogenation with production of the solution of the hydrogenated product; (9) loading of the solution of the stage (8) into the crystallization zone including the set of the connected in series crystallizers, in which the solution is subjected to the evaporating cooling with the controlled velocity using the significant drop of the temperature and the pressure for initiation of the crystallization process of the terephthalic acid, at the pressure of the solution in the end of the zone of the crystallization is atmospheric or below; (10) conduct condensation of the dissolvent evaporated from the crystallizers and guide the condensed dissolvent back into the zone of the crystallization by feeding the part of the condensed dissolvent in the line of removal of the product of the crystallizer, from which the dissolvent is removed in the form of the vapor; and (11) conduct separation of the solid crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid by separation of the solid material from the liquid under the atmospheric pressure. The method allows to obtain the target product in the improved crystalline form.

EFFECT: the invention ensures production of the target product in the improved crystalline form.

8 cl, 3 tbl, 2 dwg, 3 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for isolating crystalline terephthalic acid comprising less 150 mas. p. p. per million (ppm) of p-toluic acid with respect to weight of terephthalic acid. Method involves the following steps: (1) preparing a solution containing from 10 to 35 wt.-% of dissolved terephthalic acid wherein from 150 to 1100 ppm of p-toluic acid is dissolved with respect to mass of terephthalic acid at temperature from 260°C to 320°C and under pressure providing maintaining the solution in liquid phase; (2) charge of solution from step (1) to crystallization zone comprising multitude amount of associated crystallizers wherein the solution is subjected for cooling at evaporation at the controlled rate by the moderate pressure and temperature reducing resulting to crystallization of terephthalic acid and wherein the solution pressure at the end of crystallization zone is equal to atmosphere pressure or lower; (3) condensation of solvent evaporated from crystallizers and recovering the condensed solution to the crystallization zone to place of descending flow from crystallizer wherein solvent is removed by evaporation, and (4) isolation of solid crystalline terephthalic acid comprising less 150 ppm of p-toluic acid with respect to the terephthalic acid mass by separation of the phase liquid-solid substance under atmosphere pressure. The advantage of method is preparing the end product in improved crystalline form and carrying out the process under atmosphere pressure or pressure near to atmosphere pressure.

EFFECT: improved method of crystallization.

3 cl, 1 dwg, 1 tbl, 2 ex

FIELD: crystal growing.

SUBSTANCE: invention relates to adipic acid crystals and treatment thereof to achieve minimum crystal caking. Crystals are prepared by crystallization of adipic acid from aqueous medium or between treating it with aqueous solution. Crystals are then subjected to ripening stage, that is crystals are held at temperature between 10 and 80°C until content of exchangeable water in crystals falls below 100 ppm, while using an appropriate means to maintain ambient absolute humidity at a level of 20 g/m3. Renewal of ambient medium is accomplished by flushing crystal mass with dry air flow having required absolute humidity. Means to maintain or to lower absolute humidity contains moisture-absorption device placed in a chamber. Content of exchangeable water in crystals is measured for 300 g of adipic acid crystals, which are enclosed in tightly sealed container preliminarily flushed with dry air and containing 2 g of moisture absorbing substance. In chamber, temperature between 5 and 25°C is maintained for 24 h. Content of water will be the same as amount of water absorbed by absorbing substance per 1 g crystals. Total content of water exceeds content of exchangeable water by at least 20 ppm.

EFFECT: minimized caking of crystals and improved flowability.

13 cl, 5 ex

The invention relates to an improved method of reducing the content of 4-carboxybenzene in the production of terephthalic or 3-carboxymethylthio in the production of isophthalic acid, comprising: (a) dissolving crude terephthalic acid or crude isophthalic acid in a solvent at a temperature of from 50 to 250With obtaining a solution; (b) crystallization of the purified acid from this solution by reducing the temperature and/or pressure; (C) the Department specified crystallized terephthalic acid or isophthalic acid from the solution; (d) adding an oxidant to the reactor oxidation carboxyanhydride for oxidation specified filtered solution of stage (C), leading to the transformation of 4-carboxybenzene or 3-carboxymethylthio in terephthalic acid or isophthalic acid; (e) evaporating the solvent from this solution from step (d); (f) cooling the concentrated solution from step (e) for crystallization additional quantities of purified terephthalic acid or isophthalic acid and filtering the specified slurry and recycling the most part, the mother liquor from step (f) in the devices is

FIELD: chemistry.

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

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

28 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a thermal separation method using fractional condensation of a product-gas mixture, obtained through heterogeneous catalysed partial oxidation of propene and/or propane in gaseous phase to acrylic acid, for separating at least one mass flow, concentrated with acrylic acid, from a product-gas mixture containing acrylic acid, which involves continuous static operation of at least one device for thermal separation, containing at least one effective separation chamber with a fractionation column which has mass-transfer trays as built-in separating elements, in which the product-gas mixture is loaded, containing acrylic acid as at least one mass flow, and from which at least one mass flow containing acrylic acid is unloaded under the condition that, the overall mass flow loaded into the effective separation chamber and obtained from combining separate mass flows loaded into the separating chamber, contains X wt % components distinct from acrylic acid, the mass flow which is unloaded from the effective separation chamber with the largest content of acrylic acid, contains Y wt % components distinct from acrylic acid, ratio X:Y is ≥5, effective separation chamber, except the loading and unloading place, is bordered by a solid phase and contains, besides the mass-exchange trays as built-in separating elements in the fractionation column, at least one circulating heat exchanger, and total volume of the chamber, filled with liquid phase, is ≥1 m3, wherein temperature of the liquid phase is at least partially ≥80°C, when the effective separation chamber is divided into n separate volume elements, wherein the highest and lowest temperature of liquid phase in a separate volume element differ by not more than 2°C, and the volume element in the effective separation chamber is solid, total dwell time ttotal.

≤20 h, where A = (Ti-To)/10°C, To= 100°C, Ti = arithmetic mean value of the highest and lowest temperature of the ith volume element in the liquid phase in °C, msi = total mass of acrylic acid in the volume of the liquid phase of the ith volume element, mi = total liquid phase mass unloaded from the ith volume element, and is the sum of all volume elements i, under the condition that, volume elements i with liquid phase mass mi and as volume elements with a dead zone are also not included in the sum of all volume elements i, as well as volume elements i, which do not contain liquid phase, and total amount of liquid phase contained in volume elements with a dead zone is not more than 5 wt % of the total amount of liquid phase contained in the effective separation chamber.

EFFECT: separation of mass flow concentrated with acrylic acid.

10 cl, 12 dwg, 2 ex, 2 tbl

FIELD: chemistry.

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

EFFECT: improvement of the method of producing acetic acid.

8 cl, 1 dwg

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