Acetic acid production method

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

 

The technical field to which the invention relates

The present invention relates to a method for production of acetic acid and, in particular, to an improved method of reducing the number and/or removal of reducing the permanganate compounds formed during the production of acetic acid by carbonyliron methanol in the presence of metals of group VIII, which is the carbonylation catalysts. More specifically, the present invention relates to an improved method of reducing the number and/or removal of reducing the permanganate compounds or their precursors from the intermediate flows of the process of obtaining acetic acid by the above method carbonylation.

The level of technology

The most widely currently used methods for the synthesis of acetic acid in industry most commonly used catalytic carbonylation of methanol with carbon monoxide, as described in U.S. patent No. 3769329 issued Paulik and other 30 October 1973, the carbonylation Catalyst contains rhodium, dissolved or dispersed in a liquid reaction medium or deposited on a solid inert carrier, and halogenated promoter catalyst, an example of which is methyliodide. Rhodium can be introduced into the reaction system in any of many possible forms. When the ode halide promoter is also not decisive. The patentees describe a large number of applicable promoters, for the most part, organic iodides. The most common and convenient is the reaction by the continuous ozonation of gaseous carbon monoxide through the liquid reaction medium in which is dissolved catalyst.

Improvement of known methods carbonylation of any alcohol with obtaining a carboxylic acid having one atom more than the original alcohol, in the presence of a rhodium catalyst is offered free of assigned U.S. patents No. 5001259, published March 19, 1991, 5026908, published on 25 January 1991, 5144068, published September 1, 1992, and European patent # EP 0161874 B2, published July 1, 1992, indicate that acetic acid is produced from methanol in a reaction medium containing acetate, methylguanosine, especially methyliodide, in the presence of rhodium in a catalytically effective the concentration. In these patents States that the stability of the catalyst and the performance of the carbonylation reactor can be maintained at an unexpectedly high level, even at very low concentration of water in the reaction medium, such as 4 wt.% or less (although usually in industrial practice, the concentration of water in support of approximately 14-15 wt.%, by creating in reacts the Onna environment, along with a catalytically effective concentration of rhodium and at least a low concentration of water, given the concentration of iodide ions in addition to those that are present in the form of moduledata. These iodide ions are in a simple salt, preferably lithium iodide. The patent also indicates that the concentration of acetate and iodide are important parameters that affect the rate of carbonylation of methanol with the formation of acetic acid, especially at low concentrations of water in the reactor. By using relatively high concentrations of acetate and iodide can get an unexpectedly high degree of stability of the catalyst and the performance of the reactor, even if the water contained in the liquid reaction medium in a concentration of about 0.1 wt.%, such a low that it is determined as "negligible concentration of water. In addition, in a reaction medium increases the stability of the rhodium catalyst, for example, the resistance of the catalyst to deposition, especially at the stages of product recovery. At these stages in distillation for the extraction of acetic acid as the product tends removal of the catalyst of carbon monoxide, which in the conditions maintained in the reaction vessel, is a ligand stabilizing the rhodium. U.S. patent No. 5001259, 5026908 and 5144068 included in the description of this is subramania by reference.

It was found that although during the process of carbonylation with obtaining acetic acid at a low concentration of water decreases the formation of such by-products as carbon dioxide, hydrogen and propionic acid, the amount of other impurities usually present in trace quantities, can in this case be increased, and the quality of acetic acid due to attempts to increase productivity through improved catalysts or changing the reaction conditions sometimes worse.

The presence of trace amounts of impurities adversely affect the quality of acetic acid, especially if they are contained in the recirculated stream, which, among other things, may lead over time to increase their number. Impurities acetic acid, reducing permanganate - metric identified when testing the quality of acetic acid is most widely used in industry method include carbonyl compounds, unsaturated carbonyl compounds. In this document, the term "carbonyl" refers to compounds containing aldehyde or ketone functional group, such compounds may be saturated or unsaturated. Learn more about impurities in the process of carbonylation see Catalysis of Organic Reaction (Catalysis of organic reactions), 75, 369-380 (1998.

The present invention is directed to reducing the number and/or delete connections, reducing permanganate, such as acetaldehyde, acetone, methyl ethyl ketone, butyric aldehyde, CROTONALDEHYDE, 2-atolkachova aldehyde, 2-ethylmalonic aldehyde, etc. and the products of aldol condensation. The application of the present invention can also reduce the amount of propionic acid.

The above-described carbonyl impurities such as acetaldehyde can react with iodide promoters of the catalyst with the formation of alkyl iodides groups with multiple carbon atoms, such as ethyliodide, propyliodide, butylidene, pentylidene, hexylidene, etc. it is Desirable to separate such alkalinity from the reaction products, since even small amounts of these impurities in the finished acetic acid can lead to poisoning of the catalyst used in the production of vinyl acetate, connections, often derived from acetic acid. Thus, the present invention may also serve to reduce or remove alkylation with multiple carbon atoms, in particular With2-C12alkylation. Therefore, since the source of many of the impurities is acetaldehyde, to reduce the content of alkylation with multiple carbon atoms is main - this withdrawal from the process of carbonyl impurities, especially acetaldehyde.

Traditional methods of removing such impurities include processing of the product stream containing acetic acid, oxidizing agents, ozone, water, methanol, activated carbon, amines, etc. This may or may not be combined with the distillation of acetic acid. Most often, the treatment includes repeated distillation of the final product. Also known about removing carbonyl impurities from the flow of organic substances by processing these streams with amino compounds such as hydroxylamine, which interacts with the carbonyl compounds with the formation of Asimov, followed by distillation with the mission of the Department of treated organic products from the reaction products of education Asimov. However, additional processing of the final product increases the cost of the implementation process, and distillation of the treated acetic acid can lead to the formation of other impurities.

Although it is possible to obtain acetic acid with a relatively high degree of purity, acetic acid formed as a result of the above process for the carbonylation of low concentration of water and subsequent treatment, often due to the presence of a small proportion of residual impurities, does not meet the requirements against the AI permanganate test. Since the amount permanentny sample is an important indicator of industrial tests, the requirements of which must meet the product that you want to use in the future for various purposes, the presence of impurities, reducing permanganate, is undesirable. In addition, until now, was considered unacceptable from an economic or commercial point of view to remove from acetic acid, small amounts of such impurities by distillation, since the boiling point of some impurities close to the boiling temperature of acetic acid or halogenated promoter catalysts, such as methyliodide.

Thus, there is a need to identify economically acceptable ways to remove impurities in the implementation of the carbonylation, not leading to contamination of the final product or increase costs. So, there was disclosed a method for the production of acetic acid with a high degree of purity by adjusting the concentration of acetaldehyde in the reaction solution and keep it below a certain value, for example 1500 parts per million. It is argued that while maintaining the concentration of acetaldehyde below this threshold it is possible to suppress the formation of impurities, so that for acetic acid with a high degree of purity is required only to distil the crude product

It was also reported that carbonyl impurities present in the product stream containing acetic acid, are concentrated in the upper chase columns of light fractions. Therefore, the upper wrap columns of light fractions were treated with amino compounds such as hydroxylamine), which interact with the carbonyl compounds with the formation of derivatives Akimov, which, in turn, can be separated from the remainder of the upper shoulder strap distillation and, ultimately, to obtain acetic acid with a higher value of the permanganate test.

The famous description of other methods of production of acetic acid with high purity, which States that the concentration of acetaldehyde equal to 400 parts per million or less, is supported in the reactor by removing acetaldehyde by distillation. Streams to be processed in order to remove acetaldehyde include a light fraction containing mainly water, acetic acid and methyl acetate; heavy fraction containing predominantly methyliodide, methyl acetate and acetic acid; top zipper containing predominantly methyliodide and acetate; or recirculated stream is formed by connecting the light and heavy fractions.

Free assigned U.S. patents No. 6143930 and 6339171 reported that it is possible to significantly reduce the IC number of undesirable impurities in acetic acid by a multi-step cleaning of the upper shoulder strap columns of light fractions. In these patents discloses a cleaning method in accordance with which the upper shoulder strap light fraction is subjected to distillation twice, in both cases taking the top wrap of acetaldehyde and returning the enriched methyliodide the residue in the reactor. A large part of the acetaldehyde from enriched acetaldehyde distillate obtained after two-stage distillation, if necessary, extracted with water and disposed of, and the raffinate from a much lower concentration of acetaldehyde return to the reactor. U.S. patent No. 6143930 and 6339171 included in the description of the present invention by reference.

Although the above methods can successfully remove carbonyl impurities from the system carbonylation and, for the most part, adjusting the concentration of acetaldehyde and solve the problem of reducing permanganate samples ready acetic acid, they still can be improved. There remains a need for alternative method, characterized by an increased efficiency of removal of acetaldehyde. The present invention is a variant of alternative solutions.

The invention

The present invention relates to a method for production of acetic acid and, in particular, to an improved method of reducing the number and/or removal of regenerating perman is Anat compounds and alkylation, formed during the production of acetic acid by carbonyliron methanol in the presence of metals of group VIII, which are catalysts for the carbonylation. More specifically, the present invention relates to an improved method of reducing the number and/or removal of reducing the permanganate compounds or their precursors from the intermediate flows of the process of obtaining acetic acid by the above method carbonylation.

In the first aspect of the present invention provides a method of reducing the number and/or removal of reducing the permanganate compounds produced during carbonyliron suitable for carbonyliron reagent with the aim of obtaining product carbonyl containing acetic acid. This method involves the following stages: (a) separating the carbonylation product to get the gaseous top product containing acetic acid and a less volatile fraction of the catalyst; (b) distillation of the gaseous top product with obtaining purified acetic acid and low-boiling gaseous top product containing methyliodide, water, acetic acid, methyl acetate and at least one reducing permanganate compound; (c) condensation of low-boiling gaseous top product and dividing it into two liquid fractions - heavy and light; () distillation light liquid fraction in a separate distillation column to obtain a second gaseous top shoulder straps and balance, containing fraction more high-boiling liquid, where the second gaseous top zipper enriched, relatively light liquid fraction, reducing the permanganate compounds; (e) condensing the second gaseous top product and aqueous extraction of the condensed stream to the receiving stream, an aqueous solution of acetaldehyde containing reducing permanganate compounds, and the raffinate, containing methyliodide. In some embodiments, this method can be carried out with the abstraction of the distillation column of stage (d) side product containing methyl acetate, or without such assignment.

In another aspect the present invention provides a method of reducing the number and/or removal of reducing the permanganate compounds produced during carbonyliron suitable for carbonyliron reagent with the aim of obtaining product carbonyl containing acetic acid. This method involves the following stages: (a) separating the carbonylation product to get the gaseous top product containing acetic acid and a less volatile fraction of the catalyst; (b) distillation of the gaseous top product with obtaining purified acetic acid and low-boiling gaseous top product containing methyliodide, water, acetic acid, methyl acetate, and at least, one is about reducing permanganate connection; (c) condensation of low-boiling gaseous top product and dividing it into two liquid fractions - heavy and light; (d) distilling a light liquid fraction in a separate distillation column to obtain a second gaseous top product and residue containing fraction more high-boiling liquid, where the second gaseous top zipper enriched, relatively light liquid fraction, reducing the permanganate compounds and where the residue containing fraction more high-boiling liquid, enriched, relative to the specified second gaseous top product, acetate; (e) condensing the second gaseous top product and aqueous extraction of the condensed stream to the receiving stream water solution acetaldehyde containing reducing permanganate compounds, and the raffinate, containing methyliodide. In some embodiments, this method can be carried out with the abstraction of the distillation column of stage (d) side product containing methyl acetate, or without such assignment.

In a third aspect the present invention provides a method of reducing the number and/or removal of reducing the permanganate compounds produced during carbonyliron suitable for carbonyliron reagent with the aim of obtaining product carbonyl containing uksosn the Yu acid. This method involves the following stages: (a) separating the carbonylation product to get the gaseous top product containing acetic acid and a less volatile fraction of the catalyst; (b) distillation of the gaseous top product with obtaining purified acetic acid and low-boiling gaseous top product containing methyliodide, water, acetic acid, methyl acetate and at least one reducing permanganate compound; (c) condensation of low-boiling gaseous top product and dividing it into two liquid fractions - heavy and light; (d) distilling a light liquid fraction in a separate distillation column to obtain a second gaseous upper shoulder strap and residue containing fraction more high-boiling liquid, where the second gaseous top zipper enriched, relatively light liquid fraction, reducing the permanganate compounds; (e) allocating a side product containing methyl acetate, from the distillation column of stage (d), where the residue containing fraction more high-boiling liquid, and the specified side zipper enriched, relative to the specified second gaseous top product accumulating in their acetate; (f) condensing the second gaseous top product and aqueous extraction of the condensed stream to the receiving water flow is about the solution of acetaldehyde, containing reducing permanganate compounds, and the raffinate, containing methyliodide.

A brief description of the drawing, which illustrates various embodiments of the present invention.

Although the present invention allows various modifications, specific implementation shown in the drawing as an example and hereinafter will be described in detail. However, it should be understood that the present invention is not limited to individual described forms. Rather, the present invention covers all modifications, equivalents and variations that are included in the scope of the invention defined by its formula.

Description of illustrative embodiments

The present invention relates to a method for production of acetic acid and, in particular, to an improved method of reducing the number and/or removal of reducing the permanganate compounds formed during the production of acetic acid by carbonyliron methanol in the presence of metals of group VIII, which are catalysts for the carbonylation. More specifically, the present invention relates to an improved method of reducing the number and/or removal of reducing the permanganate compounds or their precursors from the intermediate flows of the process of obtaining acetic acid specified FPIC is BOM carbonylation.

In particular, the present invention relates to a method, in accordance with which the condensed light fraction of the upper shoulder strap columns of light fractions is subjected to a single distillation with getting the top of the shoulder strap, which is subjected to extraction for selective reduction and/or elimination of reducing the permanganate compounds from the process. Among other advantages, the present invention can reduce the number and/or delete reducing permanganate compounds using a combination of single distillation and extraction, in contrast to previously proposed methods in which to reduce or remove reducing the permanganate compounds of the condensed light fraction of the upper shoulder strap columns of light fractions is used more than one distillation column, and is used or not used for extraction. Additional benefits include, among other things, reduce energy consumption, number of units and related costs.

The following describes illustrative embodiments of the present invention. In this description in the interest of clarity, does not show all features of an actual implementation of the method. Of course it is clear that the development of any such actual case for business travelers and tourists who needs to take numerous specific solutions aimed at achieving specific goals of the developers, such as the constraints imposed by the characteristics of the system and business conditions, which differ for different occasions implementation of the method. Moreover, it is clear that such a development process is complex and lengthy, but nevertheless, it is common practice for specialists in this field, to which this description will be useful.

Cleaning method which is the object of the present invention is applicable for any option carbonylation of methanol (or other suitable to carbonyliron reagent, including, but not limited to, methyl acetate, methylformate, dimethyl ether or mixtures thereof) in acetic acid in the presence of metals of group VIII, which is the carbonylation catalysts, such as rhodium, and halogenated promoter and a catalyst. A particularly good option of this process is catalyzed by a rhodium carbonylation of methanol to acetic acid at a low concentration of water is described in U.S. patent No. 5001259.

It is usually assumed that the rhodium component of the catalyst system is present in the form of complex compounds of rhodium with halogen, providing at least one of the ligands in this complex connection. In addition, suppose that in addition to coordination with the halogen, there is coordination shall include the relationship of rhodium and carbon monoxide. The rhodium component of the catalyst system can be introduced into the reaction zone in the form of a metallic rhodium, rhodium salts, such as oxides, acetates, iodides, carbonates, hydroxides, chlorides, etc. or other compounds, all of which allow you to get in the reaction medium complex compounds of rhodium.

Halogenated promoter of this catalytic system consists of halogenated compounds, representing halogenorganics connection. That is, can be used alkylhalogenide, Ariely and substituted alkali or arily. Preferably the halogenated promoter is present in the form of alkylhalogenide. Even more preferably the halogenated promoter is present in the form of alkylhalogenide, in which the alkyl radical is an alkyl radical of the alcohol, which is the raw material for carbonylation. So, when carbonyliron methanol in acetic acid halogenated promoter is methylguanosine and, more preferably, methyliodide.

Used the liquid reaction medium may contain any solvent that is compatible with this catalytic system, and may include pure alcohols or mixture of alcohol supplied as raw materials, and/or the desired carboxylic acid and/or esters of these two compounds. The preferred solvent and liquid is Acciona environment of the carbonyl process at a low concentration of water contains the desired carboxylic acid. So, when carbonyliron of methanol to acetic acid is the preferred solvent includes acetic acid.

Water present in the reaction medium, but preferably in a concentration much lower than that until now was considered appropriate to achieve a sufficient reaction rate. Previously thought, for example, as described in U.S. patent No. 3769329 that in reactions catalyzed by rhodium carbonylation of the type which corresponds to the present invention, the addition of water has a positive effect on the reaction rate. So, on an industrial scale, this process is carried out at a concentration of water of at least about 14 wt.%. So surprise the possibility of conducting the process at a speed almost equal to or greater than the speed of reaction obtained at such relatively high concentrations of water, at a concentration of water of less than 14 wt.% and even about 0.1 wt.%.

The carbonyl process is most applicable for the production of acetic acid in accordance with the present invention, the desired reaction rate even at low water concentrations by maintaining in the reaction medium specific concentration of ester produced carboxylic acid and an alcohol, preferably the alcohol, which is the raw material for carbonyliron the Oia, and the extra amount of iodide ions in addition to those that are present in the form of moduledata. Preferably, ester represented acetate. Additional iodide ions are preferably introduced in the form of iodide, preferably lithium iodide. It was found, for example, as reported in U.S. patent No. 5001259 that at low concentration of water, methyl acetate and iodide lithium increase the reaction rate only when both are present in relatively high concentrations, and that the promotion is higher when these components are present simultaneously. It is believed that the concentration of iodide ions is maintained in the reaction medium is preferred reaction system carbonylation, is quite high compared with what is known about the use of halide salts in the reaction systems of this type. The absolute concentration of iodide-itnow is not a limitation of the present invention.

The carbonylation reaction of methanol with obtaining acetic acid can be carried out by bringing into contact of methanol supplied as raw material, with gaseous carbon monoxide, barotrauma through the reaction medium on the basis of the acetic acid solution containing the rhodium catalyst, the promoter methyliodide, acetate and more soluble iodide, over easy for the formation of the desired product of the carbonylation conditions of temperature and pressure. There is no doubt, that it is important that the concentration in the catalytic system of iodide-ions, and is not associated with iodide ions, cations, and that at a given molar concentration of iodide ions, the nature of the cation is not as significant as the effect of the concentration of iodide ions. In the reaction medium may be any metal iodide or any organic cation or Quaternary cation such as a Quaternary amine or phosphine, or inorganic cation, provided that this salt is sufficiently soluble in the reaction medium to obtain the necessary concentration of iodide ions. When iodide is a salt of the metal, it is preferable that the metal included in the group consisting of metals of groups IA and IIA of the periodic table contained in the “Handbook of Chemistry and Physics,” CRC Press, Cleveland, Ohio, 2002-03 (83-nd edition). In particular, you can use the iodides of alkali metals, and particularly suitable is lithium iodide. During low water concentration, the most acceptable from the point of view of the present invention, additional iodide ions, in addition to the existing in the form of moduledata, usually present in the catalyst solution in such amounts that the total concentration of iodide ions is from about 2 to about 20 wt.%, the acetate is usually present in amounts from about 0.5 d is approximately 30 wt.%, methyliodide usually present in amounts from about 5 to about 20 wt.%; the rhodium catalyst is usually present in amounts from about 200 to about 2000 parts per million.

Typical carbonylation reaction temperature ranges from about 150 to about 250°C, temperature range from about 180 to about 220°C. is preferred. The partial pressure of carbon monoxide in the reactor can vary widely, but typically is from about 2 to about 30 atmospheres, preferably from about 3 to about 10 atmospheres. Taking into account the partial pressure of by-products and vapour pressure liquids present the total pressure in the reactor is from about 15 to about 40 atmospheres.

A typical installation for the implementation of the reaction and extraction of acetic acid used for the carbonylation of methanol to acetic acid to rhodium catalyst with iodide promoter in accordance with the present invention, shown in the drawing; it includes liquid-phase reactor, the evaporator and the column of light fractions under the conditions and acetic acid ("pillar of light fractions") 14. In this process obtained in the reactor product of the carbonylation served in the evaporator, the TCI is Yes assign top zipper volatile ("gas") fractions, comprising acetic acid and a less volatile fraction of the catalyst (a solution containing the catalyst). Top zipper volatile fractions containing acetic acid, in the form of stream 26 is fed to the column of light fractions 14, where the distillation get purified acetic acid which take away in the form of a side of a shoulder strap 17, and a top zipper distillate 28 (hereinafter "low-boiling gaseous top zipper"). Acetic acid is allocated in the form of a side of a shoulder strap 17 may be subjected to further purification, for example in the drying column for selective separation of acetic acid from water.

The reactor and the evaporator, not shown. They belong to the standard equipment, which is now well known to experts in the field of carbonylation. The carbonylation reactor is typically a vessel with mechanical stirring or bubbling column, in which the content of the reactants in the form of liquid or suspension is maintained at a constant level automatically. Into the reactor continuously fresh methanol, carbon monoxide, water in an amount sufficient to maintain at least a negligible concentration of water in the reaction medium. In the reactor are also introducing recirculated solution of the catalyst, for example, from the bottom of the evaporator, recycled fraction under the conditions, reci colorway fraction of acetate and recycled fraction of an aqueous solution of acetic acid. Recycled fraction may contain one or more of the above-mentioned components.

Use these distillation systems, which ensure the extraction of the crude acetic acid and recycling the solution of the catalyst, under the conditions, acetate and other system components in this process. In a typical carbonylation process in the carbonylation reactor continuously serves monoxide, preferably below the mixer, mixing the contents of the reactor. Due to this mixing of the gaseous raw material is completely dispersed in the liquid reaction medium. To prevent accumulation in the reactor gaseous by-products and to maintain the partial pressure of carbon monoxide at a level appropriate for the total pressure in the reactor, the reactor purge gas flow. The temperature in the reactor is adjusted, and carbon monoxide is served with a flow rate sufficient to maintain the total pressure in the reactor.

Liquid product away from the carbonylation reactor with such a rate that the level in the reactor remained constant, the exhaust flow is directed into the evaporator. Here containing the catalyst solution (fraction of catalyst) (mainly acetic acid containing rhodium and iodide, as well as in smaller quantities - acetate, methyliodide and water is) away from the bottom of this column, and gaseous top zipper, containing acetic acid, divert from the top. Gaseous top zipper, containing acetic acid, also contains methyliodide, acetate and water. Dissolved gases leaving the reactor and supplied to the evaporator, contain a portion of carbon monoxide and may also contain gaseous by-products such as methane, hydrogen and carbon dioxide. These dissolved gases leaving the evaporator in the upper part of the shoulder strap. The upper shoulder straps in the form of stream 26 is directed into the column of light fractions 14.

In U.S. patent No. 6143930 and 6339171 reported that low-boiling gaseous upper shoulder 28 extending from the column 14 includes reducing the permanganate compounds, and in particular acetaldehyde, in a higher concentration than leaving the columns 14 of the high-boiling residue. Thus, in accordance with the present invention, low-boiling gaseous top zipper 28 containing reducing permanganate compounds, is subjected to additional processing in order to reduce the number and/or remove the existing reducing the permanganate compounds. Therefore, low-boiling gaseous top zipper 28 condense and sent to the receiver-the decanter 16. In addition to reducing the permanganate compounds low-boiling gaseous top p the rut 28 also typically contains methyliodide, methyl acetate, acetic acid and water. Process conditions preferably supported such that the low-boiling gaseous upper shoulder 28 in the decanter 16 were divided into light and heavy fractions. As a rule, low-boiling gaseous top zipper 28 is cooled to a temperature sufficient for condensation and separation of condensable under the conditions, methyl acetate, acetaldehyde and other carbonyl compounds and water in the form of two phases. Part of the stream 28 may include non-condensable gases, such as carbon dioxide, hydrogen, etc. that can blow in the form of a stream 29, as shown in the drawing.

Collected in the decanter 16 condensed light fraction usually contains water, acetic acid and reducing the permanganate compounds, as well as some quantity under the conditions and acetate. Received in decanter 16 condensed heavy fraction usually contains methyliodide, acetate and reducing permanganate connection.

In a broad sense, the present invention can be considered as an improved method of distillation for separation of reducing the permanganate compounds, mainly aldehydes, such as acetaldehyde, from low-boiling gaseous top product, in particular condensed light fraction of the low-boiling gaseous top on which she coming in the form of a stream 28 from the column of light fractions 14. In accordance with the present invention condensed light fraction of low-boiling gaseous top product, coming in the form of a stream 28 from the column of light fractions 14, is subjected to a single distillation and then single - stage or multistage extraction with the aim of reducing the number and/or removal of reducing the permanganate compounds.

This way, such as in the variants of implementation of the present invention, reflected on the drawing differs from the well-known, such as disclosed in U.S. patent No. 6339171, including the method shown in Fig. 1 of U.S. patent No. 6339171.

In accordance with the present invention is disclosed with reference to the drawing, the low-boiling gaseous top zipper 28 contains methyliodide, methyl acetate, reducing the permanganate compounds such as acetaldehyde, and optional other carbonyl compounds. Low-boiling gaseous upper shoulder strap 28 also contains water and some acetic acid.

Low-boiling gaseous upper shoulder strap 28 is then condensed and separated (in the tank 16) on the condensed heavy fraction containing the greater part under the conditions, but also containing reducing permanganate compounds, and condensed light liquid fraction (relegated to the Yu in the form of a stream 30), containing appreciable quantities of reducing the permanganate compounds, water, acetic acid, but also usually contain some amount under the conditions and acetate.

Although any of the factions of the upper shoulder strap columns of light fractions, i.e. low-boiling gaseous top of the shoulder strap 28 can then be processed to remove from this thread reducing the permanganate compounds, mainly acetaldehyde, in accordance with the present invention of reducing the permanganate compounds are removed from the condensed light liquid fraction 30.

Thus, condensed in the decanter 16 heavy liquid fraction can be easily recycled, directly or indirectly, in a reactor (not shown). For example, part of this condensed heavy liquid fraction may be recycled to the reactor as part of a stream, usually small, for example 25%, preferably less than about 20 vol.% heavy liquid fraction that is sent to the processing carbonyl compounds. This part of the stream of heavy liquid fraction can be processed separately or combined with the condensed light liquid fraction 30 for subsequent distillation and extraction of carbonyl impurities in accordance with the present invention.

In the accordance with the present invention condensed light liquid fraction 30 is sent to distillation column 18, in which is formed a second gaseous top zipper 36, enriched revitalizing the permanganate compounds, especially acetaldehyde, but also contains methyliodide, because the boiling point under the conditions and acetaldehyde close. The second gaseous top zipper 36 condense and then subjected to extraction with water to reduce the quantity and/or removal of reducing the permanganate compounds, especially acetaldehyde. According to a preferred variant of the invention, the portion of the condensed stream 36 is used for irrigation of the distillation column 18. As shown in the drawing, this can be done by filing a condensed stream 36 in the receiver of the upper ring 20 from which a portion of the condensed stream 36 can be directed at the stage of extraction (usually denoted 70) in the form of a stream 40 and another portion of the condensed stream 36 may be filed for irrigation distillation column 18 as stream 42.

Acetaldehyde is extracted with water to form a stream of an aqueous solution of acetaldehyde 72, which is usually treated as waste. Obtained by solvent extraction raffinate containing appreciable quantities under the conditions, it is desirable to return to the carbonyl process as stream 74. In various embodiments, implementation of the present invention p is the current of an aqueous solution of acetaldehyde 72 may be cleared from the aldehyde, further processed as waste, and the water is recycled in the process to use, for example for the extraction of 70.

In the present invention focuses on the extraction step, in which acetaldehyde is separated from the under the conditions. On the effectiveness of this separation affects mainly the relative solubility of acetaldehyde and under the conditions in the water. While acetaldehyde is mixed with water, methyliodide no. However, with increasing concentrations of acetate and/or methanol solubility under the conditions in the water increases, which is accompanied by a decrease of the amount under the conditions in the system. When relatively high concentrations of acetate and/or methanol separation phase under the conditions when the water extraction may not occur. The separation phase under the conditions may not occur at a sufficiently high concentration of acetic acid. Thus, it is desirable that the total concentration of methanol and methyl acetate in the distillate, which condense and sent for extraction was less than about 10 wt.%, more preferably less than about 5 wt.%, even more preferably less than about 2 wt.%, even more preferably less than about 1.5 wt.%. It is also desirable that the distillate, which condense and sent for extraction, contain less than about 3% (m is SS.) acetic acid, more preferably less than about 1 wt.%, even more preferably less than about 0.5 wt.%. Particularly preferably, the concentration of acetic acid tends to zero (wt.%).

Thus, in the method which is the object of the present invention provide a single distillation in a distillation column 18 under conditions intended for regulation, namely the reduction of the quantities of methyl acetate and acetic acid in the second gaseous top chase 36. Minimize the quantities of methyl acetate and acetic acid in the second gaseous top chase 36, preferably reach while maintaining the second gaseous top chase 36 concentration of acetaldehyde higher than in the residue of the distillation column 18. It is desirable that the residue of the distillation column 18 contains less than about 0.3 wt.% acetaldehyde, more preferably less than about 0.2 wt.%, even more preferably less than about 0.1 wt.%. Particularly preferably, the concentration of acetaldehyde tends to zero (wt.%).

In ways that are relevant to prior art, for example, as shown in Fig. 1 in U.S. patent No. 6339171 have two stage distillation order to obtain the final gaseous distillate containing a small quantity of acetate, metal is Nola and acetic acid, so this distillate was subjected to extraction with water for the selective separation of acetaldehyde from under the conditions. In such ways, related to the prior art, the water and acetic acid is separated, preferably in the form of a remainder of the first column, then the acetate is contained in the distillate. After that, the acetate is separated, preferably in the form of the remainder in the second column. In the known prior art does not indicate that the acetate, acetic acid and water with high efficiency to take in as residue single column distillation, with no unwanted accumulation of acetaldehyde in the balance. The prior art also does not indicate that acetaldehyde can with high efficiency concentrated in the distillate single column distillation, with no unwanted accumulation of acetate in the distillate. The authors of the present invention found that this separation can be accomplished by a single distillation, which improves processing performance.

Thus, in accordance with one embodiments of the present invention shown in the drawing, the low-boiling gaseous top zipper 28 condense in the receiver decanter 16, where the specified thread razdelau is located on the condensed heavy liquid fraction and a condensed light liquid fraction 30. The condensed light liquid fraction 30 is sent to distillation column 18 in the form of a stream 30/32. In this and other embodiments, implementation of the present invention the portion of the stream 30 can be abstracted into a column of light fractions 14 for irrigation in the form of a stream 34.

In a distillation column 18 are formed of the second gaseous top shoulder straps 36 and remaining more high-boiling liquid fraction 38. The second gaseous top zipper 36 enriched, with respect to the condensed light liquid fraction 30, reducing the permanganate compounds, especially acetaldehyde. The second gaseous top zipper 36 is deprived, in relation to the said condensed light liquid fraction 30, methyl acetate, methanol and/or acetic acid (preferably all three substances). The remainder of the more high-boiling liquid fraction 38 enriched, relative to the specified second gaseous upper ring 36, methyl acetate, methanol and/or acetic acid (preferably, all three substances). It is desirable that the second gaseous upper shoulder 36 has been enriched, relative to the more high-boiling liquid fraction 38, reducing the permanganate compounds, especially acetaldehyde. The remainder of the more high-boiling liquid fraction 38 can be retained and preferably remains in the process.

Specialists in this field, for which p is ecstasy interest in the present description, can develop and operate the distillation column, which allows to obtain provided by the present invention results. This work, although it's long and complicated, nevertheless is for professionals common practice. Therefore, implementation of the present invention may not be necessarily limited by the specific parameters of the individual distillation columns or parameters of its operation, such as the total number of plates, point of supply of raw materials, the reflux, the temperature of the raw material, temperature phlegmy, the temperature profile of the column, etc.

In addition, in accordance with the first embodiment of the present invention the second gaseous top zipper 36 is subjected to extraction with water (stage generally indicated 70) to remove and/or reduce the amount of reducing permanganate compounds, especially acetaldehyde. Acetaldehyde is extracted with water to form a stream of an aqueous solution of acetaldehyde 72, which is enriched by reducing the permanganate compounds, especially acetaldehyde. The flow of an aqueous solution of acetaldehyde 72 then usually treated as waste, although in some embodiments of the invention emit acetaldehyde, and water recycle in the process. The raffinate, containing mainly methyliodide, chelation is correctly returned to the carbonylation process as stream 74. The efficiency of extraction will depend on the number of stages of extraction and relationships of quantities of supplied water and raw materials.

In accordance with the first or other variants of implementation of the present invention the stage of extraction of water 70 may be implemented as a single-stage or multistage extraction on any equipment designed for extraction. Preferred is a multi-stage extraction. For example, stage extraction 70 can be implemented by connecting stream 40 with water followed by direction of the composition in the mixer and then into the separator. In the case of multi-stage extraction can be used several successive mixers and separators. Optionally, but preferably, a multistage extraction is carried out in a single vessel, equipped with a set of dishes. This tank can be equipped with blades or other devices for mixing with the aim of improving the efficiency of extraction. In this tank for multistage extraction stream 40 is preferably injected from one side of the tank, and the water on the other side or in such a way as to ensure the counter.

Mutual solubility of the two phases during extraction may increase with temperature. Therefore, it is desirable to carry out the extraction with primacom combination of temperature and pressure, to the contents of the extractor remained in the liquid state. In addition, it is desirable to minimize the flow temperature 40 to minimize the likelihood of polymerization and condensation involving acetaldehyde. The water used in the extraction step 70, preferably is an internal thread, i.e. supported water balance in the reaction system. In the extraction step to improve the Department under the conditions, that is, to mitigate losses under the conditions with a stream of an aqueous solution of acetaldehyde 72 may be entered dimethyl ether, which can be enjoyed outside or formed in the process.

In accordance with the second embodiment of the present invention, also reflected in the drawing, the low-boiling gaseous top zipper 28 condense in the decanter 16, where it is divided into condensed heavy liquid fraction and a condensed light liquid fraction 30. Light condensed liquid fraction 30 is sent to distillation column 18 in the form of a stream 30/32. In this and other embodiments, implementation of the present invention the portion of the stream 30 can also be assigned to the column of light fractions 14 for irrigation in the form of a stream 34. In a distillation column 18 are formed of the second gaseous top shoulder straps 36 and remaining more high-boiling liquid fraction 38. Also set aside laterally the shoulder straps 80, containing acetate.

Thanks to the abstraction side of the shoulder strap 80 distillation column can be operated at conditions that are favorable for obtaining a higher concentration of acetaldehyde in the second gaseous top chase 36, at the same time provides a mechanism for the removal of acetate, which, otherwise, can accumulate in the center of the distillation column 18 or overcrowded and get the second gaseous top zipper 36. Side zipper 80 containing methyl acetate, preferably leave in the process.

In the second embodiment of the invention the second gaseous top zipper 36 is enriched, relative to the light condensed liquid fraction 30, reducing the permanganate compounds, especially acetaldehyde. The second gaseous top zipper 36 is deprived, in relation to a specified light condensed liquid fraction 30, methyl acetate, methanol and/or acetic acid (preferably all three substances). The second gaseous top zipper 36 is deprived, in relation to the specified side of the shoulder straps 80 and preferably also to a more high-boiling liquid fraction 38, methyl acetate, methanol and/or acetic acid (preferably all three substances). Preferably the second gaseous top zipper 36 is enriched, relative to the side shoulder strap 80 and more high-boiling liquid fraction 38, the reduction of alluaudite permanganate compounds, especially acetaldehyde.

In addition, in accordance with the second embodiment of the present invention the second gaseous top zipper 36 is subjected to extraction with water (usually stage is denoted 70) in order to remove the remaining reducing the permanganate compounds, especially acetaldehyde. In accordance with the second embodiment of the invention the extraction was carried out as described in the first embodiment.

When carrying out the process in accordance with the first embodiment of the present invention without discharge side product were obtained following the results of separation in a distillation column 18:

Componentwt.% in the flow 30/32wt.% in stream 36wt.% in the thread 38
Methyliodide1,574,5<0,1
The acetate6,01,46,1
Methanol4,00,24,1
Acetic who Isleta 15<0,115,3
Water731,674,5
Acetaldehyde0,522,20,1

It is expected that during the process in accordance with the second embodiment of the present invention with the discharge side product can be obtained the following results separation in a distillation column 18:

Componentwt.% in the flow 30/32wt.% in stream 36wt.% in the thread 38wt.% flow 80
Methyliodide1,546,8<0,128,7
The acetate4,00,41,760,4
Methanol1,0<0,11,0 0,5
Acetic acid15<0,115,70,5
Water780,881,67,4
Acetaldehyde0,552<0,12,5

As a result of work on the invention has succeeded in reducing the number and/or removed from the process reducing the permanganate compounds and their precursors, impurities of alkylation with several carbon atoms in the alkyl group, propionic and other, higher carboxylic acids. Was also shown the ability to reduce and/or remove significant amounts of acetaldehyde and its derivatives and, therefore, maintain the concentration of propionic acid in ready-acetic acid below about 500 parts per million by weight, preferably below about 300 ppm and most preferably below 250 parts per million.

In modifications of the embodiments of the present invention, it is important to inhibit the formation in the distillation column 18 different polim the ditch and the condensation products involving aldehyde. Acetaldehyde is polymerized to form metaldehyde and paraldehyde is recommended. These polymers are typically low molecular weight, less than about 200. Can also produce polymers of acetaldehyde with higher molecular weight. Such polymers with higher molecular weight (molecular weight about 1000) are formed, as I believe, when processing the light fraction and are viscous and thixotropic. Acetaldehyde can also participate in spam aldol condensation.

The formation of these impurities, i.e. metaldehyde, paraldehyde is recommended and polymers of acetaldehyde with higher molecular weight, can be suppressed by introducing into the distillation column 18 of the flow of washing liquid containing at least water and/or acetic acid.

Although the present invention has been described with reference to preferred variants of its implementation, there are many possible modifications and variations which are obvious to experts in this field, for which the present description is of interest. Therefore, it is understood that the present invention fully encompasses all such changes and modifications and that they do not go beyond the limits of the following claims or their equivalents.

1. The method of reduction and/or removal is reducing the permanganate compounds, formed at carbonyliron suitable for carbonyliron reagent with the aim of obtaining product carbonyl containing acetic acid, comprising the steps:
(a) separating the carbonylation product to get the gaseous top product containing acetic acid, methanol, methyliodide, water, methyl acetate and at least one reducing permanganate compound, including acetaldehyde, and less volatile fraction of the catalyst;
(b) distillation of the gaseous top product with obtaining purified acetic acid and low-boiling gaseous top product containing methanol, methyliodide, water, acetic acid, methyl acetate and at least one reducing permanganate compound, including acetaldehyde;
(c) condensation of low-boiling gaseous top product and dividing it into condensed heavy liquid fraction containing methyliodide and methyl acetate, and the condensed light liquid fraction comprising water, acetic acid and at least one reducing permanganate compound, including acetaldehyde;
(d) distilling a light liquid fraction in a separate distillation column to obtain a second gaseous top product, including methyliodide and at least one reducing permanganate compound, on the tea acetaldehyde, and residue containing fraction more high-boiling liquid containing methyl acetate, water and acetic acid, where the second gaseous top zipper enriched relatively light liquid fraction reducing the permanganate compounds;
(e) condensing the second gas of the upper shoulder strap, including methyliodide and at least one reducing permanganate compound, including acetaldehyde, and water extraction of the condensed stream to obtain a stream of an aqueous solution containing reducing permanganate compounds, including acetaldehyde, and a raffinate containing methyliodide.

2. The method according to claim 1, wherein the total concentration of methyl acetate and methanol in the second gaseous upper pursuit is less than about 5 wt.%.

3. The method according to claim 1, in which the concentration of acetaldehyde in the residue containing fraction more high-boiling liquid is less than about 0.3 wt.%.

4. The method according to claim 1, wherein the second gaseous upper shoulder strap is subjected to extraction in the presence of dimethyl ether.

5. The method according to claim 1, wherein stage (d) carry out without discharge of the distillation column side product containing methyl acetate, and where the residue containing fraction more high-boiling liquid, enriched in relation to the specified second gaseous at the top of the shoulder strap by acetate.

6. The method according to claim 5, in which the total concentration of methyl acetate and methanol in the second gaseous upper pursuit is less than about 5 wt.%.

7. The method according to claim 5, in which the concentration of acetaldehyde in the residue containing fraction more high-boiling liquid is less than about 0.3 wt.%.

8. The method according to claim 1, including additional abstraction from the rectifying column at stage (d) side product containing methyl acetate, where the residue containing fraction more high-boiling liquid, and a side zipper enriched with respect to the specified second gaseous upper shoulder strap accumulate the acetate.

9. The method according to claim 8, in which the total concentration of methyl acetate and methanol in the second gaseous upper pursuit is less than about 5 wt.%.

10. The method according to claim 8, in which the concentration of acetaldehyde in the residue containing fraction more high-boiling liquid is less than about 0.3 wt.%.

11. The way to reduce and/or remove reducing the permanganate compounds produced during carbonyliron suitable for carbonyliron reagent with the aim of obtaining product carbonyl containing acetic acid, comprising the steps:
(a) separating the carbonylation product to get the gaseous top the first shoulder strap, containing acetic acid, methanol, methyliodide, water, methyl acetate and at least one reducing permanganate compound, including acetaldehyde, and less volatile fraction of the catalyst;
(b) distillation of the gaseous top product with obtaining purified acetic acid and low-boiling gaseous top product containing methanol, methyliodide, water, acetic acid, methyl acetate and at least one reducing permanganate compound, including acetaldehyde;
(c) condensation of low-boiling gaseous top product and dividing it into condensed heavy liquid fraction containing methyliodide and methyl acetate, and the condensed light liquid fraction comprising water, acetic acid and at least one reducing permanganate compound, including acetaldehyde;
(d) distilling a light liquid fraction in a separate distillation column to obtain a second gaseous top product, including methyliodide and at least one reducing permanganate compound, including acetaldehyde, and the residue containing fraction more high-boiling liquid containing methyl acetate, water and acetic acid, where the second gaseous top zipper enriched, relatively light liquid fraction, reducing the permanganate compounds is, including acetaldehyde; and
(e) condensing the second gas of the upper shoulder strap, including methyliodide and at least one reducing permanganate compound, including acetaldehyde, and water extraction of the condensed stream to obtain a stream of an aqueous solution of acetaldehyde containing reducing permanganate compounds, including acetaldehyde, and a raffinate containing methyliodide.

12. The method according to claim 11, in which stage (d) carry out without discharge of the distillation column side product containing methyl acetate.

13. The method according to item 12, in which the total concentration of methyl acetate and methanol in the second gaseous upper pursuit is less than about 5 wt.%.

14. The method according to item 12, in which the concentration of acetaldehyde in the residue containing fraction more high-boiling liquid is less than about 0.3 wt.%.

15. The method according to claim 11, comprising the additional step of discharge of the distillation column of stage (d) side product containing methyl acetate, where the residue containing fraction more high-boiling liquid, and a side zipper enriched relative to the second gaseous upper shoulder strap accumulate the acetate.

16. The method according to item 15, in which the total concentration of methyl acetate and methanol in the second gaseous top chase the leaves of less than about 5 wt.%.

17. The method according to item 15, in which the concentration of acetaldehyde in the residue containing fraction more high-boiling liquid is less than about 0.3 wt.%.

18. The way to reduce and/or remove reducing the permanganate compounds produced during carbonyliron suitable for carbonyliron reagent with the aim of obtaining product carbonyl containing acetic acid, comprising the steps:
(a) separating the carbonylation product to get the gaseous top product containing acetic acid, methanol, methyliodide, water, methyl acetate and at least one reducing permanganate compound, including acetaldehyde, and less volatile fraction of the catalyst;
(b) distillation of the gaseous top product with obtaining purified acetic acid and low-boiling gaseous top product containing methanol, methyliodide, water, acetic acid, methyl acetate and at least one reducing permanganate compound, including acetaldehyde;
(c) condensation of low-boiling gaseous top product and dividing it into condensed heavy liquid fraction containing methyliodide and methyl acetate, and the condensed light liquid fraction comprising water, acetic acid and at least one reducing permanganate with the Association, including acetaldehyde;
(d) distilling a light liquid fraction in a separate distillation column to obtain a second gaseous top product, including methyliodide and at least one reducing permanganate compound, including acetaldehyde, and the residue containing fraction more high-boiling liquid containing methyl acetate, water and acetic acid, where the second gaseous top zipper enriched relatively light liquid fraction reducing the permanganate compounds;
(e) allocating a side product containing methyl acetate, from the distillation column of stage (d), where the residue containing fraction more high-boiling liquid, and a side zipper enriched relative to the specified second gaseous top product accumulating in their acetate;
(f) condensing the second gas of the upper shoulder strap, including methyliodide and at least one reducing permanganate compound, including acetaldehyde, and water extraction of the condensed stream to obtain a stream of an aqueous solution of a reducing permanganate compounds, including acetaldehyde, and a raffinate containing methyliodide.

19. The method according to p, in which the total concentration of methyl acetate and methanol in the second gaseous upper pursuit is less than approximately 5 wt%.

20. The method according to p, in which the concentration of acetaldehyde in the residue containing fraction more high-boiling liquid is less than about 0.3 wt.%.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to improved combined methods of producing acetic acid and vinyl acetate involving the following steps: (a) obtaining a first stream of product from the first reaction zone containing acetic acid, where the acetic acid is obtained via an exothermic carbonylation reaction, and where at least part of the heat obtained from the acetic acid is tapped from the first reaction zone and at least part of the heat tapped during production of acetic acid is transferred to a heat exchange system; (b) bringing the reaction stream of acetic acid containing at least a portion of acetic acid from the first stream of product into contact an oxygen-containing gas in a second reaction zone in the presence of a catalyst to obtain a second stream of product which contains vinyl acetate monomer; (c) directing at least a portion of the second stream of product to purification section for purification of at least a portion of vinyl acetate in the second stream of product; and either (d) tapping at least part of heat transferred to the heat exchange system, and delivering at least part of the heat tapped from the heat exchange system to at least one reaction stream of acetic acid and the vinyl acetate purification section, and where the heat exchange system contains a stream of a steam condensate, and where at least part of the heat tapped during production of acetic acid is delivered to the stream of steam condensate which is used to provide at least one reaction stream of acetic acid and the vinyl acetate purification section with heat tapped during production of acetic acid, where the stream of steam condensate containing heat from production of acetic acid is directed to a low-pressure evaporation vessel kept at pressure between 4.0 kg/cm2 and 5.3 kg/cm2, or (d) tapping at least part of the heat transferred to the heat exchange system, and delivering at least part of heat tapped from the heat exchange system to at least one reaction stream of acetic acid and the vinyl acetate purification section, in which a loop is used to cycle the condensate in order to remove most of the heat from production of acetic acid by directing a stream of a hot reaction solution through the heat exchanger for transferring heat to the stream of steam condensate, where the stream of steam condensate which contains heat from production of acetic acid is directed to the low-pressure evaporation vessel kept at pressure between 4.0 kg/cm2 and 5.3 kg/cm2.

EFFECT: proposed methods are useful for lowering expenses and reducing power consumption during vinyl acetate production.

10 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing acetic acid and specifically to a method of producing acetic acid via carbonylation in the presence of a rhodium catalyst system. Described is a catalyst system for producing acetic acid, which includes a carbonylation rhodium catalyst, methyl iodide, at least one heteropolyacidic promoter and a method of producing acetic acid through carbonylation of methanol and/or its reactive derivative with carbon monoxide in a liquid reaction mixture which contains methyl acetate, limited concentration of water, acetic acid and the catalyst system mentioned above.

EFFECT: faster carbonylation.

21 cl, 6 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: method involves impulse evaporation of flow discharged from reactor to form upper distillate; further treatment of upper distillate by distillation in standard operational conditions, obtaining acetic acid; running control of acetic acid formation rate by regulation of at least one independent process parametre; running control of acetic acid formation rate by regulation of at least one dependent process parametre; acetic acid formation rate reduction in response to changes in the process course of process equipment state; process control at reduced acetic acid formation rate by regulation of at least one of independent and/or dependent parametre during return of process equipment system to original state of standard operational process before the said change; increase of acetic acid formation rate until the system returns to original state of standard operational process by regulation of at least one of independent and/or dependent parametre, where non-linear multivariant regulation is based on the process model.

EFFECT: improved cost efficiency.

3 cl, 2 ex, 3 dwg

FIELD: chemistry.

SUBSTANCE: method of producing acetic acid and its ester or anhydride involves bringing methanol and/or its reactive derivative selected from methyl acetate and dimethyl ether into contact with carbon monoxide in the presence of a catalyst at temperature ranging from 250 to 600°C and pressure ranging from 10 to 200 bars, and where content of iodide in the methanol and/or its reactive derivative, carbon monoxide and catalyst is less than 500 parts/million, where the catalyst essentially consists of mordenite which contains skeleton elements in form of silicon, aluminium and one or more of other elements selected from gallium and boron, and in which copper, nickel, iridium, rhodium or cobalt is added through ion exchange or some other method.

EFFECT: high selectivity with respect to the end product and high catalyst stability.

22 cl, 3 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: described is a carbonylation method for producing a carbonylation product by bringing carbon monoxide into contact with initial material containing alcohol and/or its reactive derivative, in vapour phase using a heterogeneous heteropolyacid catalyst containing one or more metal cations selected from Cu, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd and Pt. The initial material contains 0.5-20 wt % water and water in the initial material is fresh and/or recycled.

EFFECT: increased catalyst activity, increased degree of convertion of methanol into the desired product.

35 cl, 5 ex, 3 tbl

FIELD: explosives.

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

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

34 cl, 2 dwg

FIELD: chemistry.

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

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

28 cl, 2 dwg

FIELD: chemistry.

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

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

49 cl, 3 tbl, 13 ex

FIELD: chemistry.

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

EFFECT: improvement of the method of producing acetic acid.

8 cl, 1 dwg

FIELD: chemistry.

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

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

30 cl, 3 ex, 1 tbl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a carboxylic acid synthesis method. The invention specifically relates to a method for synthesis of carboxylic acids through oxidation of a hydrocarbon with oxygen or an oxygen-containing gas, and more specifically to oxidation of cyclohexane to adipinic acid. According to the invention, the method involves a step for oxidising the hydrocarbon and at least one step for extracting the formed dicarboxylic acids from the reaction medium and, in known cases, return unconverted hydrocarbon and oxidation by-products such as ketones and alcohols which may be formed to the reaction. The disclosed method also includes a step for conversion, separation or extraction of α,ω-hydroxycarboxylic compounds formed during oxidation. This step for conversion, separation or extraction of α,ω-hydroxycarboxylic compounds involves oxidation of medium containing the said compounds in order to convert them to dibasic acids.

EFFECT: design of an efficient method of obtaining carboxylic acids.

16 cl, 10 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of purifying carboxylic acid from a mixture which contains one or more carboxylic acids selected from a group consisting of terephthalic acid, isophthalic acid, orthophthalic acid and their mixtures, and also contains one or more substances selected from a group consisting of carboxybenzaldehyde, toluic acid and xylene. The method involves: bringing the mixture into contact with a selective solvent for crystallisation at temperature and in a period of time sufficient for formation of a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation without complete dissolution of the complex salt of carboxylic acid; extraction of the complex salt and decomposition of the complex salt in the selective solvent for crystallisation in order to obtain free carboxylic acid. The mixture containing unpurified carboxylic acid is brought into contact with the selective solvent for crystallisation in order to form a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation. The complex salt is extracted and, if desired, processed for extraction of free carboxylic acid.

EFFECT: methods are especially suitable for purifying aromatic dibasic carboxylic acids such as terephthalic acid, and also enables reduction of the degree of contamination of phthalic acids with carboxybenzaldehyde isomers.

22 cl, 3 tbl, 1 dwg, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of preparing a dry residue of aromatic dicarboxylic acid containing 8-14 carbon atoms, suitable for use as starting material for synthesis of polyester, where the said method involves the following sequence of stages, for example: (a) oxidation of aromatic material in the oxidation zone to obtain a suspension of carboxylic acid; (b) removal of impurities from the suspension of aromatic dicarboxylic acid in the liquid-phase mass-transfer zone where at least 5% liquid is removed, with formation of a residue or suspension of aromatic dicarboxylic acid, and a stream of mother solution, where the liquid-phase mass-transfer zone includes a device for separating solid substance and liquid; (c) removal of residual impurities from the suspension or residue of aromatic dicarboxylic acid obtained at stage (b) in the zone for countercurrent washing with a solvent to obtain a residue of aromatic dicarboxylic acid with the solvent and a stream of mother solution together with the solvent, where the number of steps for countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, and the said solvent contains acetic acid, (d) removal of part of the solvent from the residue of aromatic dicarboxylic acid together with the solvent obtained at stage (c) in the zone for countercurrent washing with water to obtain a residue of aromatic dicarboxylic acid wetted with water and a stream of liquid by-products together with the solvent/water, where the number of countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, where stages (b), (c) and (d) are combined into a single liquid-phase mass-transfer zone, and directing the residue of aromatic dicarboxylic acid wetted with water directly to the next stage (e), (e) drying the said residue of aromatic dicarboxylic acid wetted with water in the drying zone to obtain the said dry residue of aromatic dicarboxylic acid suitable for synthesis of polyester, where the said residue wetted with water retains the form of residue between stages (d) and (e).

EFFECT: design of an improved version of the method of preparing dry residue of aromatic dicarboxylic acid.

21 cl, 4 dwg

FIELD: explosives.

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

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

34 cl, 2 dwg

FIELD: chemistry.

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

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

28 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to improved method of recovering (meth)acrolein or (meth)acrylic acid, including stage of cooling of gaseous reaction mixture containing (meth)acrolein or (meth)acrylic acid obtained by reaction of catalytic oxidation in vapour phase of one or both reagents selected from (A) propane, propylene or isobutylene and (B) (meth)acrolein, with molecular oxygen or gas, containing molecular oxygen, to temperature 140-250°C; contacting of said gaseous reaction mixture with solvent, whose temperature is 20-50°C, in recovery installation for recovering (meth)acrolein or (meth)acrylic acid in solvent, where said recovery installation contains contact zone, where gaseous reaction mixture contacts with solvent, having transversal section of round form and many devices of gaseous reaction mixture supply for supplying gaseous reaction mixture into contact zone, devices of gaseous reaction mixture supply are installed in contact zone at the same height directed towards contact zone centre, gaseous reaction mixture is supplied to contact zone from devices of gaseous reaction mixture supply and is subjected to collision straight in one point of contact zone, and recovery installation does not have device which prevents direct collision of gaseous mixture supplied from devices of gaseous reaction mixture supply. Invention also relates to recovery installation for recovering (meth)acrolein or (meth)acrylic acid.

EFFECT: ensuring efficient recovering (meth)acrolein or (meth)acrylic acid from gas containing (meth)acrolein or (meth)acrylic acid, preventing polymerisation.

7 cl, 5 dwg, 4 ex

FIELD: chemistry.

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

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

20 cl, 1 tbl, 1 dwg

FIELD: chemistry.

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

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

17 cl, 1 tbl, 1 dwg

FIELD: chemistry.

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

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

8 cl, 1 tbl, 1 dwg, 1 ex

FIELD: chemistry.

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

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: 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

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