WO2002068375A1 - Procede de distillation azeotropique - Google Patents

Procede de distillation azeotropique

Info

Publication number
WO2002068375A1
WO2002068375A1 PCT/JP2002/001372 JP0201372W WO02068375A1 WO 2002068375 A1 WO2002068375 A1 WO 2002068375A1 JP 0201372 W JP0201372 W JP 0201372W WO 02068375 A1 WO02068375 A1 WO 02068375A1
Authority
WO
WIPO (PCT)
Prior art keywords
carboxylic acid
aliphatic carboxylic
azeotropic distillation
acid ester
oil phase
Prior art date
Application number
PCT/JP2002/001372
Other languages
English (en)
Japanese (ja)
Inventor
Motoki Numata
Takayuki Isogai
Original Assignee
Mitsubishi Chemical Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Chemical Corporation filed Critical Mitsubishi Chemical Corporation
Publication of WO2002068375A1 publication Critical patent/WO2002068375A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
    • C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
    • C07C51/46—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation by azeotropic distillation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
    • B01D3/36—Azeotropic distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/48—Separation; Purification; Stabilisation; Use of additives
    • C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
    • C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation

Definitions

  • the present invention relates to an azeotropic distillation method.
  • the present invention is particularly effective when azeotropic distillation separates water from an aqueous feed stream containing an aliphatic carboxylic acid, such as acetic acid, to recover the aliphatic carboxylic acid.
  • the present invention relates to a method for producing an aromatic carboxylic acid by a liquid phase oxidation reaction in a solvent containing an aliphatic carboxylic acid, which method is suitable for recovering aliphatic sulfonic acid used as a solvent. Background technology>
  • the separation of distillation is improved by adding a substance (azeotropic agent or entrainer) that forms an azeotropic mixture with any of the component substances to a mixture that is difficult to separate by distillation. improves.
  • An industrial application of the azeotropic distillation method is to add acetic acid and water to a mixture of acetic acid and water by adding acetic acid n-propyl acetate or n-butyl acetate to form an azeotropic mixture with water and performing azeotropic distillation. There is a method of obtaining high-purity acetic acid from a water mixture.
  • One of the fields where the azeotropic distillation method can be applied is production of aromatic carboxylic acids. That is, the azeotropic distillation method can be applied in the process of recovering the solvent from the aromatic carboxylic acid production process.
  • an aromatic carboxylic acid such as terephthalic acid
  • a solvent containing an aliphatic carboxylic acid such as acetic acid.
  • a mixed vapor of aliphatic carboxylic acid and water is taken out from the reactor, and a feed stream containing a condensate of this vapor is distilled to separate water from the aliphatic carboxylic acid, and to remove the dehydrated aliphatic carboxylic acid.
  • An operation such as recirculating at least a part to the reaction raw material liquid adjusting tank is performed.
  • acetic acid which is widely used as the above solvent
  • rectification is usually used to separate water from the mixture of acetic acid and water, but azeotropic distillation may be more advantageous depending on installation and variable costs.
  • the main aspects of azeotropic distillation technology development can be broadly classified into separation, controllability, reduction of reflux ratio, and post-treatment of condensate from the azeotropic distillation column overhead.
  • the higher the reflux ratio the better the operational stability, and the lower the reflux ratio, the lower the operational stability.
  • the reflux ratio is below a certain limit value, the separability of the azeotropic distillation itself rapidly deteriorates.
  • This limit value is generally called the minimum reflux ratio, which is determined by the composition of the feed solution, the type of the entrainer, the position (height) of the feed solution to the azeotropic distillation column, the number of feed lines, It depends on the method of returning the reflux liquid and the method of returning the end trainer.
  • Japanese Patent Publication No. 62-41 219 discloses a method of reducing the oil phase component entrained in the water phase after separating the vapor condensate at the top of the azeotropic distillation column by liquid-liquid separation. Focusing on certain isobutyl acetate and an aliphatic carboxylic acid ester as an impurity, it has been proposed to strip the aqueous phase solution and collect them. However, this is intended to prevent loss due to entrainment of the oil phase component in the aqueous phase, and is not a technique for solving all the problems derived from the aliphatic carboxylic acid esters as impurities. The aliphatic carboxylic acid ester enters the distillation column along with the feed and accumulates in the oil phase. Tokiko Sho 62—
  • the method described in Japanese Patent No. 42119 is a technique for preventing a part of the aliphatic carboxylic acid ester of the accumulated impurities from being lost due to entrainment from the aqueous phase, and the aliphatic carboxylic acid contained in the oil phase.
  • the increase in the concentration of the aliphatic carboxylic acid ester deteriorates the separability between acetic acid and water in azeotropic distillation, and causes a loss of the active ingredient (acetic acid). Since then, various companies have proposed techniques for preventing the accumulation of impurities (aliphatic carboxylic esters) in the oil phase.
  • Korean Patent Publication No. 941-142292 discloses that the product obtained by condensing the vapor at the top of an azeotropic distillation column is subjected to liquid-liquid separation, and then the aliphatic aliphatic impurities entrained in the oil phase are removed.
  • a method for recovering a carboxylic acid ester by distillation has been proposed.
  • this method has a problem that a large amount of energy is required for separating the above-mentioned aliphatic carboxylic acid ester due to poor separability between the aliphatic carboxylic acid ester in the oil phase and the entrainer.
  • Japanese Patent Application Laid-Open No. 2000-72714 discloses that the vapor at the top of an azeotropic distillation column is fractionated and the fatty acid carboxylate ester of impurities in the remaining gas is absorbed and collected in acetic acid. A method has been proposed. However, in this method, since the entrainer component is entrained by the condensation, the aliphatic carboxylic acid ester alone cannot be taken out, resulting in loss of the effective component (entrainer component) and contamination of the product.
  • WO 98/45 239 proposes a method for recovering aliphatic carboxylic acid esters as impurities by distilling the vapor at the top of an azeotropic distillation column and distilling the remaining gas.
  • This technology also has an improvement in the amount of heat used, but it cannot isolate the aliphatic sulfonic acid ester, and is similar to the technology described in other patents in that it has a dedicated route for recovery. Problem. Further, in the publication, since the water concentration in the azeotropic composition is low, there is a problem that a large amount of an end trainer must be used to remove water by azeotropic distillation.
  • the amount of entrainer used in the azeotropic distillation depends on the azeotropic composition, but is generally at least 1 times, for example, 2 to 5 times the weight ratio to water. Therefore, in addition to the large amount of the entrainer itself, since the entrainer is usually used in circulation, it has a lower boiling point than acetic acid and is less soluble in water (for example, methyl-para-xylene acetate ) Accumulate on one side. Therefore, when the amount of impurities contained increases, the amount of the oil phase greatly increases. Therefore, the allowable range in which the aliphatic carboxylic acid ester, which is one of the impurities, can be contained is narrow.
  • the present invention has been made in view of the above circumstances, and has been made in consideration of the concentration of an aliphatic carboxylic acid ester as an impurity in an aqueous phase of a condensate obtained by condensing a distillate at the top of an azeotropic distillation column.
  • the starting point is a new idea obtained from the point of interest of the ratio with the entrainer concentration. It is known that the recovery of organic components from the aqueous phase is almost an essential operation, but the present invention has actively applied it and found a technique for suppressing an increase in aliphatic carboxylic acid esters as impurities. .
  • the present invention is based on this technology, and aims to provide an azeotropic distillation method that suppresses energy consumption and achieves excellent separation performance by introducing a simple process. .
  • the gist of the present invention resides in an azeotropic distillation method having at least the following steps (1) to (5).
  • Step (1) A solution to be distilled containing water, an aliphatic carboxylic acid and an aliphatic carboxylic acid ester is azeotropically distilled using an entrainer to obtain an aliphatic phenolic acid having reduced water content, A step of obtaining a water-enriched overhead distillate.
  • Step (2) a step of condensing the top distillate to obtain a gas and a condensate separated into two phases, an aqueous phase and an oil phase.
  • Step (3) a step of separating an aqueous phase and an oil phase of the condensate.
  • Step (4) A step of distilling a part or the whole of the aqueous phase obtained by the fractionation to obtain the overhead distillate containing the aliphatic carboxylic acid ester and having a reduced water content.
  • Step (5) The overhead distillate obtained in the step (4) is distilled together with a part or all of the oil phase collected in the step (3), and the aliphatic carboxylic acid obtained by the distillation is distilled. A step of collecting part or all of the ester outside the system.
  • FIG. 1 is a flowchart showing an example of a distillation process for carrying out the present invention.
  • 11 is an azeotropic distillation column
  • 13 is a liquid-liquid separation tank 1)
  • 2 is a stripping tower
  • 24 is an entrainer and a recovery column.
  • the “solution to be distilled” means a mixed solution containing a target substance to be purified and a substance whose concentration is to be reduced (hereinafter referred to as “reduced substance”).
  • Reduced substance means the third component added to perform azeotropic distillation.
  • the “azeotropic region” means a region where the concentration of the entrainer is at least 0.1% by weight in the entire composition existing as a liquid phase in the region.
  • the term “azeotropic distillation column” means a distillation column for distilling the above-mentioned solution to be distilled and the entrainer.
  • a solution to be distilled containing water, an aliphatic carboxylic acid and an aliphatic carboxylic acid ester is azeotropically distilled using an entrainer to obtain a water content as a target substance.
  • an aliphatic carboxylic acid having a reduced water content and a water-enriched overhead distillate is obtained.
  • the concentration of the entrain in the bottom liquid is 100 ppm or less.
  • the concentration of the aliphatic carboxylic acid in the condensate of the distillate at the top of the azeotropic distillation column is preferably not more than 1,000 p. It is recycled to the system of the liquid-phase oxidation reaction of substituted aromatic hydrocarbons.
  • the solution to be distilled in the present invention is a mixed solution containing the target substance and the reducing substance. Further, the entrainer to be added and the reducing substance form an azeotropic mixture, and the azeotropic temperature of the target substance is reduced. There is no particular limitation as long as it is lower than the boiling point. Further, it may contain a substance which does not substantially affect the azeotropic distillation.
  • the end trainer in the present invention is not particularly limited as long as the effect is exhibited. It does not need to be a single component, and may be a mixture of two or more components that form a heterogeneous azeotrope with the reducing substance, or may contain a part of a decomposition product of the component. You may.
  • the azeotropic distillation column in the present invention may be either a packed column or a tray column.
  • the supply position of the solution to be distilled is not particularly limited, it is usually the middle stage of the azeotropic distillation column, and the optimum position may be determined in consideration of the composition in the column in order to optimize the separation efficiency.
  • the operation of the azeotropic distillation column can be carried out under normal pressure, under pressure, or under reduced pressure, and the system may be a batch system or a continuous system. More preferably, it is carried out continuously under normal pressure.
  • the concentration of the above-mentioned aliphatic carboxylic acid ester in azeotropic distillation is arbitrary, but it is necessary to contain 3 to 50% by weight in the oil phase containing the entrainer to obtain a stable and high concentration of water from an aliphatic carboxylic acid such as acetic acid. From the viewpoint of separation.
  • the kind of the aliphatic carboxylic acid ester as an impurity contained in the solution to be distilled is not particularly limited, but usually, an ester of the aliphatic carboxylic acid of the target substance is mentioned, and specifically, for example, acetic acid Methyl.
  • the entrainer is selected in consideration of the type of the coexisting aliphatic carboxylic acid, but a known compound used for azeotropic distillation of a mixed solution containing the aliphatic carboxylic acid and water can be used.
  • esters such as butyl formate, n-propyl acetate, isobutyl acetate, n-butyl acetate, amyl acetate, n-butyl propionate, and isobutyl propionate, dichloromethyl ether, ethyl isoamyl ether, and linoleisoea Ethers such as mill ether and di-n-butylinoleether; halogenated hydrocarbons such as ethylene dichloride and chlorobenzene; ketones such as acetone chloride, dipropionoleketone, methylbutinoleketone and arinoleacetone; tonolenene and xylene Compounds that can form an
  • the solution to be distilled is a solvent used for the production of an aromatic carboxylic acid such as terephthalic acid, etc.
  • p in the solution to be distilled originates from the aromatic carboxylic acid production raw material.
  • Decomposition products of other substances such as xylene and methyl acetate may be contained.
  • composition of the aliphatic carboxylic acid and water in the solution to be distilled is arbitrary.
  • the present invention is applied to a mixed solution containing an aliphatic sulfonic acid and water having a water content in the range of 4 to 99% by weight, preferably in the range of 10 to 70% by weight / 0. You.
  • the solution to be distilled to which the method of the present invention is applied include those recovered in a process of producing an aromatic carboxylic acid in which a liquid-phase oxidizing and purifying an alkyl-substituted aromatic hydrocarbon in a solvent containing an aliphatic carboxylic acid.
  • a condensed and recovered product of a mixed vapor from a liquid-phase oxidation reactor of an alkyl-substituted aromatic hydrocarbon and a recovered product in which steam acetic acid in waste gas discharged from the reactor is absorbed by water.
  • the liquid and amount can be selected and used. These liquids may be mixed or treated independently.
  • a step (2) a step of condensing the overhead distillate to obtain a gas and a condensate separated into two phases, a water phase and an oil phase; Step (3): Separating each phase of the condensate separately.
  • a bottoms containing the target substance having a reduced concentration of the reduced substance is obtained from the bottom of the column, and the bottom is mainly composed of the reduced substance and the entrainer from the top of the column.
  • An azeotropic vapor (top distillate) is obtained.
  • the vapor obtained from the top is condensed to obtain a condensate and a gas.
  • This condensate is usually obtained as a two-phase liquid consisting of an aqueous phase mainly composed of the reducing substance and an oil phase mainly composed of the entrainer.
  • step (3) the two-phase condensate is separated into an aqueous phase and an oil phase.
  • fractionation means examples include liquid-liquid separation using a decanter or the like, but are not particularly limited as long as the purpose is achieved. In order to separate the two phases in this way, it is preferable to use an entrainer and a reducing substance that gives a heterogeneous azeotrope such that the aqueous phase and the oil phase constituting the condensate do not mix uniformly.
  • the amount of the aliphatic carboxylic acid ester recovered from the oil phase is calculated by subtracting the amount of the aliphatic carboxylic acid ester recovered from the aqueous phase by 2 It is preferable to set it to 0 times or less. This is, for example, “the flow rate of the oil phase per unit time X the concentration of the aliphatic carboxylic acid ester in the oil phase” and “the flow rate of the aqueous phase per unit time X the concentration of the aliphatic carboxylic acid ester in the aqueous phase” Is obtained.
  • the amount of the aliphatic carboxylic acid ester that can be recovered from the aqueous phase decreases, and the effect of the present invention may be reduced.
  • the amount is preferably 18 times or less, particularly 15 times or less. Is preferred.
  • the part is preferably recycled to the azeotropic distillation column.
  • the amount of entrainer recycled to the azeotropic distillation column is theoretically given by the amount of water to be discharged from the azeotropic distillation column and the composition of the azeotropic mixture.
  • the optimum amount of entrainer may be determined from the concentration of aliphatic carboxylic acid in the condensate of the effluent from the azeotropic distillation column and the concentration of entrainer in the bottoms.
  • a new trainer may be supplied to compensate for the lost trainer that has gone out of the system.
  • a part of the phase (aqueous phase) mainly containing the reducing substance is subjected to the step (4) described later.
  • the remaining aqueous phase may be returned to the azeotropic distillation column as a reflux liquid.
  • a part of the aqueous phase may be returned to the azeotropic distillation column as a reflux liquid.
  • water which is the main component of the phase (aqueous phase) mainly composed of the reducing substance, may be partially discarded after being reused in the process.
  • the method of returning water as a reflux liquid includes, for example, a method of returning to the top of the azeotropic distillation column and a method of returning to the middle stage of the column.
  • the amount of water reflux is usually set to about 0.1 to 3 depending on the ratio (return water amount / discharged water amount).
  • step (4) a part or all of the separated aqueous phase is distilled to obtain an overhead distillate containing the above-mentioned aliphatic sulfonic acid ester having a reduced water content.
  • the aqueous phase separated from the condensate of the distillate at the top of the azeotropic distillation tower (mainly water, which is a reducing substance) is sent to the distillation tower, and from the top of the distillation tower, A method for obtaining the above-mentioned aliphatic carboxylic acid having a reduced water content is exemplified. What is obtained from the bottom of the distillation column in this distillation is mainly water. Even if this water is discarded outside the system, a part of it is returned to the azeotropic distillation column as a reflux liquid.
  • the top distillate obtained in the step (4) is distilled together with part or all of the oil phase fractionated in the step (3), and the above-mentioned aliphatic product obtained by the distillation is distilled off. Carbo Part or all of the acid ester is recovered out of the system.
  • the distillation column in step (5) is for the purpose of recovering the entrainer.
  • the distillate at the top of step (4) and the oil phase of the condensate of the distillate at the top of the azeotropic distillation column collected in step (3) are collected. Feed part or all and distill.
  • This distillation separates the entrainer from the impurity aliphatic carboxylic acid ester.
  • the supply of the components to be distilled to step (5) was controlled so that at least 20% of the aliphatic carboxylic acid ester was derived from the overhead obtained in step (4). Is preferable in terms of energy efficiency.
  • the entrainer is collected from the bottom of the column, and part or all may be collected outside the system, or part or all may be returned to the azeotropic distillation column.
  • the aliphatic carboxylic acid ester which is an impurity, may be partially or entirely recovered outside the system.
  • the condensate of the azeotropic distillation column top distillate that is, the entrainer and the aliphatic A mixture of carboxylic acid ester
  • the gas obtained in step (2) may be supplied together with the oil phase.
  • the oil phase separated in the step (3) and the entrainer obtained in the step (5) are supplied to the azeotropic distillation column as described in JP-B-61-31091.
  • the azeotropic distillation column As described in JP-B-61-31091.
  • the effect of changing the operating conditions can be easily reflected, and the response can be speeded up.
  • water obtained in the step (2) or the step (4) as described in Japanese Patent Publication No. 10-504556, water is returned to the middle stage of the azeotropic distillation column as a reflux liquid to the column. It can also be used for a method of controlling the impurity concentration at the bottom of the column by controlling the amount.
  • the alkyl-substituted aromatic hydrocarbons accumulated in the entrainer may be separated directly from the entrainer, or may be azeotropic as described in JP-A-10-504556. It may be withdrawn from the middle stage of the distillation column. Further, the extracted product can be purified as described in WO 97/29068. Next, a method for producing an aromatic carboxylic acid of the present invention to which the azeotropic distillation method of the present invention is applied will be described.
  • the aromatic carboxylic acid as the target compound is any aromatic carboxylic acid, such as aromatic monocarboxylic acid, aromatic dicarboxylic acid, and aromatic tricarboxylic acid.
  • aromatic carboxylic acid such as aromatic monocarboxylic acid, aromatic dicarboxylic acid, and aromatic tricarboxylic acid.
  • aromatic monocarboxylic acid such as aromatic monocarboxylic acid, aromatic dicarboxylic acid, and aromatic tricarboxylic acid.
  • the corresponding alkyl-substituted aromatic hydrocarbon such as monoa / lequinolebenzene, dianolequinolebenzene, and trialkylbenzene is oxidized, preferably in a liquid phase.
  • the method of the present invention is preferably applied when the aromatic dicarboxylic acid, particularly the aromatic carboxylic acid is terephthalic acid.
  • P-xylene is used as the alkyl-substituted aromatic hydrocarbon as a raw material.
  • an aliphatic carboxylic acid When performing the oxidation reaction in a liquid phase, an aliphatic carboxylic acid is usually used as a solvent.
  • the aliphatic carboxylic acid which is a solvent for the liquid phase oxidation reaction for example, acetic acid is preferred, and the amount of the solvent is usually 2 to 6 times by weight based on the starting alkyl-substituted aromatic hydrocarbon.
  • the water concentration in the oxidation reaction system is usually 4 to 25% by weight, preferably 7 to 20% by weight.
  • a catalyst is usually used.
  • a transition metal compound such as manganese, cobalt, iron, chromium, and nickel is used.
  • a bromine compound may be used as the co-catalyst.
  • acetoaldehyde-methylethyl ketone or the like is used as a promoter for the cobalt catalyst.
  • oxidizing agent molecular oxygen or air is used, but usually air is used. Air having a high oxygen concentration by mixing oxygen gas, or air having a low oxygen concentration by mixing inert gas such as nitrogen gas, may be used.
  • the reaction temperature of the liquid phase oxidation may be appropriately selected, and is usually from 120 ° C to 220 ° C.
  • the reaction temperature is generally preferably 160 ° C. or less.
  • the pressure may be appropriately selected in the same manner.
  • acetic acid may be in a pressure range in which it can be in a gaseous state.
  • the heat of the oxidation reaction is mainly removed by flash evaporation of the aqueous acetic acid solvent. That is, the fraction (exhaust gas) from the oxidation reactor mainly contains evaporated acetic acid and water, and a small amount of low-boiling products and unreacted alkyl-substituted aromatic hydrocarbons among the by-products of the oxidation reaction. Contains. This vapor is cooled and condensed into a liquid by a condenser, and a part of the vapor is usually returned to the oxidation reactor as an oxidation reaction solvent.
  • Another part is sent to a dehydration tower for the purpose of removing water generated by the oxidation reaction, is subjected to the azeotropic distillation of the present invention, and the dehydrated acetic acid is sent again to the oxidation reactor as an oxidation reaction solvent.
  • the liquid-phase oxidation of alkyl-substituted aromatic hydrocarbons is usually performed in one reactor and, if necessary, in multiple reactors. If necessary, the reaction solution after the oxidation reaction is sent to one or two or more successively reduced pressure crystallizers, where it is cooled to the temperature corresponding to each pressure by the flash cooling action of the solvent to produce Most of the aromatic carboxylic acids crystallized as crystals, forming a slurry. The slurry is separated into a cake of aromatic rubonic acid crystals and an oxidation reaction mother liquor by any means of crystal separation, such as rotary vacuum filtration, centrifugation, or any other suitable separation method.
  • the cake of the aromatic carboxylic acid crystals is washed with acetic acid or water as required, and then the attached solvent is removed with a dryer. Further, if necessary, the slurry is re-slurried in a reaction mother liquor mainly composed of water, and is subjected to a hydrogenation step and then recrystallized to reduce impurities in the crystal and to be purified. Subsequently, after performing operations such as solid-liquid separation, washing, and drying, an aromatic carboxylic acid is obtained.
  • the azeotropic distillation method of the present invention and the method for producing aromatic carboxylic acid using the azeotropic distillation method will be described with reference to FIG. FIG.
  • 11 is an azeotropic distillation column.
  • the solution to be distilled containing water, aliphatic carboxylic acid (such as acetic acid) and aliphatic carboxylic acid ester of impurities is supplied from lines 40, 41, 42, etc.
  • the composition of the solutions is usually different from each other), and the end trainer
  • the mixture is supplied to an azeotropic distillation column 11 where azeotropic distillation is performed.
  • Heat is applied by heat exchanger 14 to add the heat required for distillation.
  • Heating oil or steam is used as a heating source.
  • a temperature higher than the normal pressure boiling point of acetic acid, specifically, 0.35 MPa steam is used.
  • the azeotropic mixture vapor containing the reducing substance whose concentration is to be reduced by azeotropic distillation and the entrainer (the distillate from the top of the azeotropic distillation column) is sent to the cooler 12 from the top of the azeotropic distillation column 11. It is condensed here.
  • the obtained condensate is separated into two phases in a liquid-liquid separation tank 13 and is separated therefrom.
  • An appropriate separation means may be selected depending on the properties of the azeotrope.
  • a part of the phase (aqueous phase) mainly composed of the reducing substance in the liquid-liquid separation tank 13 is sent to the stripping tower 21 through the line 17.
  • a part of the aqueous phase may be used as a reflux for water to the azeotropic distillation column 11 through the line 16.
  • the entrainer is circulated through line 15. Lines 15 and 16 are connected, if necessary, to the top or middle of the azeotropic distillation column 11.
  • the number of the lines 15 and 16 may be one or more, respectively.Furthermore, using a common line, the entrainer and the reducing substance are sent together to the azeotropic distillation column 11 It may be returned, or it may be returned by individual lines.
  • a liquid mainly containing a target substance for example, aliphatic carboxylic acid
  • a target substance for example, aliphatic carboxylic acid
  • the water and the aromatic carboxylic acid raw material mainly from line 22 in the middle stage of the tower are used.
  • a liquid comprising a substituted aromatic hydrocarbon is extracted.
  • organic components and in the method for producing an aromatic carboxylic acid of the present invention, mainly an aliphatic carboxylic acid ester as impurities are recovered, and reduced substances such as water separated by azeotropic distillation are collected in a line 1. It is recycled to the aromatic carboxylic acid production process through 8, where it is effectively used or discarded.
  • the organic components recovered in the stripping tower 21 are sent to an entrainer through a line 23 to an entrainer 24, where the entrainer and the aliphatic carboxylic acid ester of impurities are removed. Is separated into The entrainer is recovered from the bottom of the column and returned to the azeotropic distillation column 11 via lines 25 and 15.
  • the aliphatic carboxylic acid ester is recovered through line 26.
  • the aliphatic carboxylic acid ester may be stored as desired, or may be partially or wholly circulated in the oxidation reaction step for producing an aromatic carboxylic acid.
  • the entrainer and a mixture of the aliphatic carboxylic acid ester branched off at line 27 are directly introduced into the entrainer-one recovery tower 24. Although not shown, cooling is performed. It is also possible to introduce the gas generated in the vessel 12 into the entrainer-one recovery tower 24.
  • the amount of the aliphatic carboxylic acid ester recovered outside the system is indicated as the amount of the substance discharged from the line 26.
  • This effluent may contain impurities such as entrainers, water, aliphatic hydrocarbons, etc., and may be liquids, gases or mixtures thereof.
  • the amount of the aliphatic carboxylic acid ester introduced into the recovery step via the aqueous phase liquid of the condensed liquid phase at the top of the azeotropic distillation column 11 depends on the amount of the substance flowing through the line 17. Indicated as quantity.
  • the recovery ratio is at least 20%, preferably at least 30%, more preferably at least 40%, based on the total amount of the above-mentioned aliphatic carboxylic acid esters recovered outside the system, through the aqueous phase. Is preferable from the viewpoint of energy efficiency.
  • the above-mentioned aliphatic carboxylic acid ester can be accompanied, albeit very slightly, in the bottom liquid 25 of the entrainer recovery tower 24. Therefore, in the present invention, the above-mentioned recovery ratio is calculated based on the ratio of the amount of the aliphatic carboxylic acid ester via the aqueous phase to the amount of the aliphatic sulfonic acid ester introduced into the recovery step via the aqueous phase and the oil phase. .
  • the stream of the aliphatic carboxylic acid ester which has not passed through the aqueous phase is introduced into the entrainer-recovery column 24 through the line 27.
  • This flow may be a gas or a liquid or a mixture thereof, and the gas generated in the cooler 12 may be used in combination, as described in WO98 / 45239.
  • the concentration ratio of the aliphatic carboxylic acid ester of the impurity and the entrainer in the oil phase extracted from the liquid-liquid separation tank 13 is usually 1: 100 to 1: 2.
  • the recovery ratio is adjusted by adjusting the flow rate of the path indicated by the line 27 or the flow rate of the path indicated by the line 28.
  • the distribution of the aliphatic carboxylic acid ester as an impurity is calculated by: (total amount of the substance in the aqueous phase) / ( The greater the ratio indicated by (total amount of substances), the greater the effect of the method of the present invention. It can be obtained as, for example, (aqueous phase flow rate per unit time X concentration of the aliphatic carboxylic acid ester in the aqueous phase) Z (oil phase flow rate per unit time X concentration of the aliphatic carboxylic acid ester in the oil phase) Can be done.
  • the concentration of the above-mentioned aliphatic carboxylic acid ester in the oil phase is 1 to 50% by weight, but this concentration is determined by the amount of the above-mentioned aliphatic carboxylic acid ester to be recovered from the route shown in line 25. And the distribution ratio of the substance in the water and oil phases.
  • the amount of the aliphatic carboxylic acid ester as an impurity accompanying the oil phase is 20 times or less, preferably 17 times or less, more preferably the amount of the aliphatic carboxylic acid ester accompanying the water phase. Is preferably 15 times or less, or the water is refluxed.
  • the amount of entrainment here is determined by the product of the substance concentration and the flow rate of the liquid flowing through the route.
  • the recovery process is represented by two distillation columns, but it is also possible to connect the columns 21 and 24 and omit the reboiler of the column 24.
  • the present invention provides a greater effect in azeotropic distillation that requires separation and recovery of aliphatic carboxylic acid esters as impurities.
  • the aliphatic carboxylic acid concentration in the overhead liquid of the azeotropic distillation column is not more than 100 ppm and the can of the azeotropic distillation column
  • Example 1 Specific embodiments of the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded.
  • Example 1
  • the p-xylene was withdrawn from the line 22 at the middle stage and recovered, and methyl acetate was recovered by distillation using an entrainer recovery column 24 having 13 theoretical plates. From the top of the azeotropic distillation column 11, water having an azeotropic composition and steam containing an entrainer were obtained, which was cooled and recovered in the liquid-liquid separation tank 13. The aqueous phase liquid of the two liquid phases separated in the liquid-liquid separation tank 13 is passed through the line 17 into the stripping tower 21 with eight theoretical plates, and after removal of organic components, the line 1 It is divided into 8 and 28. Line 18 was wastewater, and line 28 was reflux water to azeotropic distillation column 11.
  • the amount of reflux water was determined so that the water reflux ratio defined by Wr / Ww became a desired value.
  • the amount (Ww) of the discharged aqueous phase liquid is 17.3 parts by weight per unit time
  • the amount of the reflux water (Wr) is 11 parts by weight
  • the water reflux ratio is 0.64. It was carried out in.
  • the organic components recovered in the stripping tower 21 are transferred to the entrainer-collection tower 24 through the line 23.
  • the entrainer was subjected to liquid-liquid separation in a liquid-liquid separation tank 13 and then circulated through a line 15 to an azeotropic distillation column 11.
  • Example 1 except that the amount of methyl acetate introduced into the recovery step via the aqueous phase condensate was reduced to 15% of the amount of methyl acetate recovered outside the system. Distillation was performed in the same manner as in Example 1.
  • the amount of heat used in the entrainer recovery tower 24 was 2.0 Gca1r.
  • azeotropic distillation can be operated with reduced energy without using a complicated distillation process. Therefore, the method of the present invention has a great effect on variable costs or environmental protection, and has a high stability due to its simplicity, and has an effect of reducing the outflow of active ingredients.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

La présente invention concerne un procédé de distillation azéotropique qui comprend les étapes (1) à (5): étape (1) : étape de distillation de manière azéotropique d'une solution à distiller contenant de l'eau, un acide carboxylique aliphatique et un carboxylate aliphatique à l'aide d'un entraîneur pour obtenir un acide carboxylique aliphatique possédant une teneur en eau réduite et une fraction lourde possédant une teneur en eau concentrée, étape (2) : étape de condensation de la fraction lourde pour obtenir un condensat gazeux et liquide séparé en une phase aqueuse et en une phase huileuse, étape (3) : étape de retrait de la phase aqueuse et de la phase huileuse du condensat de manière séparée ; étape (4) : étape de distillation d'une partie ou de l'ensemble de la phase aqueuse ainsi retirée pour obtenir une fraction lourde contenant le carboxylate aliphatique susmentionné et possédant une teneur en eau réduite, et étape (5) : étape de distillation de la fraction lourde de l'étape (4) avec une partie ou l'ensemble de la phase huileuse de l'étape (3) pour obtenir une fraction contenant le carboxylate aliphatique susmentionné et récupération d'une partie ou de l'ensemble de la fraction de carboxylate aliphatique à l'extérieur du système de distillation azéotropique.
PCT/JP2002/001372 2001-02-27 2002-02-18 Procede de distillation azeotropique WO2002068375A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2001-51553 2001-02-27
JP2001051553 2001-02-27

Publications (1)

Publication Number Publication Date
WO2002068375A1 true WO2002068375A1 (fr) 2002-09-06

Family

ID=18912316

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2002/001372 WO2002068375A1 (fr) 2001-02-27 2002-02-18 Procede de distillation azeotropique

Country Status (2)

Country Link
CN (1) CN1226267C (fr)
WO (1) WO2002068375A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109467501A (zh) * 2018-08-03 2019-03-15 内蒙古蒙维科技有限公司 聚乙烯醇母液回收单元中醋酸精制及共沸剂再生工艺和装置

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1300088C (zh) * 2005-03-25 2007-02-14 扬子石油化工股份有限公司 一种回收芳香族羧酸生产过程中原料、溶剂和副产物的方法
WO2009013623A2 (fr) * 2007-07-18 2009-01-29 Invista Technologies S.A.R.L. Distillation azéotropique avec régénération du solvant
CN102020549B (zh) * 2009-09-10 2013-07-24 中国石油化工股份有限公司 共沸精馏分离醋酸和水的连续生产方法
CN103012102B (zh) * 2011-09-27 2014-09-17 中国石油化工股份有限公司 芳族羧酸生产中回收乙酸和水的方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000009468A1 (fr) * 1998-08-11 2000-02-24 E.I. Du Pont De Nemours And Company Procede de recuperation d'acetate de methyle et d'acide acetique residuel dans la production d'acide terephtalique pur

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000009468A1 (fr) * 1998-08-11 2000-02-24 E.I. Du Pont De Nemours And Company Procede de recuperation d'acetate de methyle et d'acide acetique residuel dans la production d'acide terephtalique pur

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109467501A (zh) * 2018-08-03 2019-03-15 内蒙古蒙维科技有限公司 聚乙烯醇母液回收单元中醋酸精制及共沸剂再生工艺和装置
CN109467501B (zh) * 2018-08-03 2024-02-20 内蒙古蒙维科技有限公司 聚乙烯醇母液回收单元中醋酸精制及共沸剂再生工艺和装置

Also Published As

Publication number Publication date
CN1492850A (zh) 2004-04-28
CN1226267C (zh) 2005-11-09

Similar Documents

Publication Publication Date Title
KR100564192B1 (ko) 아크릴산 및 메타크릴산의 제조 방법
KR100690034B1 (ko) 아크릴산의 제조 방법
KR100896383B1 (ko) 방향족 디카복실산의 제조를 위한 2단계 산화 방법
JP5715318B2 (ja) アクリル酸の製造方法
JP2007091759A (ja) 相を形成させるような分離処理により、プロペンおよび／またはアクロレインを接触気相酸化させることによって得られた混合物を精製する方法
KR100658555B1 (ko) 전구체, 용매 및 메틸 아세테이트의 회수를 개선시킨 순수테레프탈산의 제조 방법
KR0152059B1 (ko) 특정 순도를 갖는 디메틸테레프탈레이트 중간생성물의 제조방법 및 용도
MX2008010939A (es) Proceso de produccion de acido carboxilico.
EP3197856B1 (fr) Production d'un acide dicarboxylique aromatique
WO2002068375A1 (fr) Procede de distillation azeotropique
MX2012013186A (es) Produccion de acidos carboxilicos aromaticos.
CN1135215C (zh) 纯对苯二酸生产中回收乙酸甲酯与残余乙酸的方法
KR20150139820A (ko) 방향족 산의 제조에서의 공비 증류에 의한 아세트산의 탈수
US4215053A (en) Production of ortho-phthalic acid and its conversion and recovery of phthalic anhydride
KR102592022B1 (ko) 산화에 의해 방향족 디카복실산을 제조하기 위한 에너지 및 환경적으로 통합된 방법
EP1989166B1 (fr) Procédé de purge de sous-produit d'oxydation polyvalent
US4215056A (en) Formation, purification and recovery of phthalic anhydride
JP2002326001A (ja) 共沸蒸留方法
EA030640B1 (ru) Увеличение скорости фильтрации очистки терефталевой кислоты путем регулировки процента воды в подаваемой на фильтр суспензии
KR100716095B1 (ko) 규격에 따른 프탈산 무수물의 제조 방법
JP2002326972A (ja) 共沸蒸留方法
US20140121406A1 (en) Pure plant mother liquor solvent extraction system and method
JP3849086B2 (ja) 芳香族カルボン酸の製造方法
WO2002068083A1 (fr) Methode de distillation azeotropique
WO2001097941A1 (fr) Procede azeotropique de distillation

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 758/MUMNP/2003

Country of ref document: IN

WWE Wipo information: entry into national phase

Ref document number: 02805492X

Country of ref document: CN

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase