KR20180064892A - Process for continuous recovering (meth)acrylic acid - Google Patents

Abstract

The present invention relates to a recovering method of (meth)acrylic acid and a device used in the recovering method. The recovering method of (meth)acrylic acid according to the present invention separately discharges (meth)acrylic acid solutions in different concentrations from a (meth)acrylic acid absorption tower (100), and uses an extraction solvent in a specific ratio during a (meth)acrylic acid extraction process, thereby securing the high recovery rate of (meth)acrylic acid and remarkably reducing the costs of purification energy.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for recovering (meth) acrylic acid,

The present invention relates to a process for the recovery of (meth) acrylic acid.

(Meth) acrylic acid is generally produced by a method of subjecting a compound such as propane, propylene, or (meth) acrolein to a gas phase oxidation reaction in the presence of a catalyst. For example, in the presence of an appropriate catalyst in the reactor, propane, propylene, and the like are converted into (meth) acrylic acid via (meth) acrolein by a gas phase oxidation reaction and (meth) acrylic acid, unreacted propane or propylene (1) A mixed gas (1) containing acrolein, inert gas, carbon dioxide, water vapor and various organic by-products (acetic acid, low boiling point byproduct, high boiling point byproduct, etc.) by the above reaction is obtained.

The (meth) acrylic acid-containing mixed gas (1) is brought into contact with an absorption solvent in the (meth) acrylic acid absorption tower (100) and recovered as an aqueous (meth) acrylic acid solution. Then, the decomposable gas in which the (meth) acrylic acid is deaerated is recycled to the synthesis reaction of (meth) acrylic acid, and some of it is incinerated and converted into harmless gas and discharged. The (meth) acrylic acid aqueous solution is extracted, distilled and purified to obtain (meth) acrylic acid.

In order to improve the recovery efficiency of such (meth) acrylic acid, various methods for controlling process conditions or process sequences have been proposed. As a method for separating water and acetic acid from the (meth) acrylic acid aqueous solution obtained in the (meth) acrylic acid absorption tower 100, a method of azeotropically distilling a distillation column using a hydrophobic solvent is known. Alternatively, a (meth) acrylic acid aqueous solution 203 is supplied to the (meth) acrylic acid extraction tower 200 and a hydrophobic solvent is used to obtain a (meth) acrylic acid extract solution 203 having reduced water content, A method of reducing energy consumption is known.

However, in the known method of recovering (meth) acrylic acid, the (meth) acrylic acid absorption tower 100 discharges a single stream aqueous solution downward. When the concentration of the discharged (meth) acrylic acid aqueous solution is to be increased, (Or distillation) load in the subsequent purification (or distillation) step when the separation efficiency of the (meth) acrylic acid absorption tower 100 is lowered and the concentration of the discharged (meth) acrylic acid aqueous solution is kept low to increase the separation efficiency, There is a limit that can not be increased.

The present invention is to provide a method for recovering (meth) acrylic acid, which can secure a high (meth) acrylic acid recovery ratio and can further reduce energy consumption in the purification process.

According to the present invention,

A) contacting a mixed gas comprising (meth) acrylic acid, organic by-products and water vapor with water in a (meth) acrylic acid absorption tower to form an aqueous (meth) acrylic acid solution;

B) discharging a (meth) acrylic acid aqueous solution (103) of a first concentration at the side of the (meth) acrylic acid absorption tower;

C) discharging a second concentration of (meth) acrylic acid aqueous solution (102) at the lowermost portion of the (meth) acrylic acid absorption tower;

(B-1) extracting (meth) acrylic acid by bringing a first concentration of a (meth) acrylic acid aqueous solution discharged to the side into an extraction solvent containing a hydrophobic organic solvent in a (meth) acrylic acid extraction tower;

D) distilling the (meth) acrylic acid extract solution extracted in the step (B-1) and the aqueous solution of the second concentration of the (meth) acrylic acid discharged in the step (C) through an azeotropic distillation process to obtain (meth) acrylic acid step; And

E) recycling the raffinate of step B-1) into the absorption water of step A)

In the step E), the weight balance is introduced as absorbing water at a point corresponding to a height of 5 to 50% from the top of the absorption tower to the bottom,

Wherein the first concentration is lower than the second concentration in the concentration of (meth) acrylic acid,

(Meth) acrylic acid, which satisfies the following formula (1).

[Equation 1]

Y1 = a x X1

In the above equation (1)

Y1 is the amount of the extraction solvent used in the step B-1)

a is less than 2.7, in terms of the extraction solvent,

X1 is the amount of water contained in the first concentration (meth) acrylic acid aqueous solution 103.

The method for recovering (meth) acrylic acid according to the present invention comprises the steps of discharging (meth) acrylic acid aqueous solution of different concentration in the (meth) acrylic acid absorption tower 100, (Meth) acrylic acid can be recovered and the continuous process can be operated with the (meth) acrylic acid which can greatly reduce energy consumption in the purification process while ensuring high (meth) acrylic acid recovery.

1 is a process diagram of a (meth) acrylic acid recovery method according to an embodiment of the present invention.
2 is a process diagram of a (meth) acrylic acid recovery method according to a comparative example of the present invention.

In the (meth) acrylic acid recovery method of the present invention,

A) contacting a mixed gas comprising (meth) acrylic acid, organic by-products and water vapor with water in a (meth) acrylic acid absorption tower to form an aqueous (meth) acrylic acid solution;

B) discharging a (meth) acrylic acid aqueous solution (103) of a first concentration at the side of the (meth) acrylic acid absorption tower;

C) discharging a second concentration of (meth) acrylic acid aqueous solution (102) at the lowermost portion of the (meth) acrylic acid absorption tower;

(B-1) extracting (meth) acrylic acid by bringing a first concentration of a (meth) acrylic acid aqueous solution discharged to the side into an extraction solvent containing a hydrophobic organic solvent in a (meth) acrylic acid extraction tower;

D) distilling the (meth) acrylic acid extract solution extracted in the step (B-1) and the aqueous solution of the second concentration of the (meth) acrylic acid discharged in the step (C) through an azeotropic distillation process to obtain (meth) acrylic acid step; And

E) recycling the raffinate of step B-1) into the absorption water of step A)

In the step E), the weight balance is introduced as absorbing water at a point corresponding to a height of 5 to 50% from the top of the absorption tower to the bottom,

Wherein the first concentration is lower than the second concentration in the concentration of (meth) acrylic acid,

Lt; RTI ID = 0.0 > (1) < / RTI >

[Equation 1]

Y1 = a x X1

In the above equation (1)

Y1 is the amount of the extraction solvent used in the step B-1)

a is less than 2.7, in terms of the extraction solvent,

X1 is the amount of water contained in the first concentration (meth) acrylic acid aqueous solution 103.

In the present invention, the terms first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

Moreover, the terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the present invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprising," "comprising," or "having ", and the like are intended to specify the presence of stated features, But do not preclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

Also in the present invention, when referring to each layer or element being "on" or "on" each layer or element, it is meant that each layer or element is formed directly on each layer or element, Layer or element may be additionally formed between each layer, the object, and the substrate.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the present specification, first, '(meth) acrylic acid' is used to collectively mean acrylic acid, methacrylic acid or a mixture thereof.

The 'mixed gas (1)' containing (meth) acrylic acid generally refers to a mixed gas (1) that can be produced when (meth) acrylic acid is produced by a gas phase oxidation reaction. That is, according to one embodiment of the present invention, at least one compound selected from the group consisting of propane, propylene, butane, i-butylene, t-butylene and (meth) acrolein (Meth) acrylic acid-containing mixed gas (1). At this time, the (meth) acrylic acid-containing mixed gas (1) contains (meth) acrylic acid, an unreacted raw material compound, (meth) acrolein, an inert gas, carbon monoxide, carbon dioxide, water vapor and various organic by-products (acetic acid, Etc.) may be included. Here, the term "light ends" or "high boiling point byproducts" refers to a kind of by-product that can be produced in the production and recovery of a desired (meth) acrylic acid, Small or large compounds are collectively referred to.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

(Meth) acrylic acid recovery method of the present invention comprises the steps of: A) contacting a mixed gas containing (meth) acrylic acid, an organic by-product and water vapor with water in a (meth) acrylic acid absorption tower to make an aqueous (meth) acrylic acid solution;

B) discharging a (meth) acrylic acid aqueous solution (103) of a first concentration at the side of the (meth) acrylic acid absorption tower;

C) discharging a second concentration of (meth) acrylic acid aqueous solution (102) at the lowermost portion of the (meth) acrylic acid absorption tower;

(B-1) extracting (meth) acrylic acid by bringing a first concentration of a (meth) acrylic acid aqueous solution discharged to the side into an extraction solvent containing a hydrophobic organic solvent in a (meth) acrylic acid extraction tower;

D) distilling the (meth) acrylic acid extract solution extracted in the step (B-1) and the aqueous solution of the second concentration of the (meth) acrylic acid discharged in the step (C) through an azeotropic distillation process to obtain (meth) acrylic acid step; And

E) recycling the raffinate of step B-1) into the absorption water of step A)

In the step E), the weight balance is introduced as absorbing water at a point corresponding to a height of 5 to 50% from the top of the absorption tower to the bottom,

Wherein the first concentration is lower than the second concentration in the concentration of (meth) acrylic acid,

Lt; RTI ID = 0.0 > (1) < / RTI >

[Equation 1]

Y1 = a x X1

In the above equation (1)

Y1 is the amount of the extraction solvent used in the step B-1)

a is less than 2.7, in terms of the extraction solvent,

X1 is the amount of water contained in the first concentration (meth) acrylic acid aqueous solution 103.

1 is a process diagram of a (meth) acrylic acid recovery method according to an embodiment of the present invention.

2 is a process diagram of a (meth) acrylic acid recovery method according to a comparative example of the present invention.

1, the method for recovering (meth) acrylic acid according to the present invention comprises the steps of A) mixing a gas (1) (1) containing (meth) acrylic acid, an organic byproduct and water vapor in a (meth) acrylic acid absorption tower 100 100) with water to form a (meth) acrylic acid aqueous solution; B) discharging a (meth) acrylic acid aqueous solution 103 of a first concentration (103) at the side of the (meth) acrylic acid absorption tower 100; C) discharging a (meth) acrylic acid aqueous solution (102) of a second concentration at a lowermost portion of the (meth) acrylic acid absorption tower (100); (Meth) acrylic acid extraction column 200 (200), which has been discharged to the side portion, is brought into contact with an extraction solvent containing a hydrophobic organic solvent to form a (meth) acrylic acid aqueous solution 103 Methacrylic acid; (D) Distilling the (meth) acrylic acid extract solution 203 extracted in the step B-1) and the (meth) acrylic acid aqueous solution 102 having the second concentration discharged in the step C) (300) to obtain (meth) acrylic acid (303); And E) recycling (201) the additional raffinate of step B-1) to the water of step A)

In the step E), the weight 201 is introduced into the absorber from the top of the absorber at a point corresponding to a height of 5 to 50%

Wherein the first concentration is lower than the second concentration in the concentration of (meth) acrylic acid,

Lt; RTI ID = 0.0 > (1) < / RTI >

[Equation 1]

Y1 = a x X1

In the above equation (1)

Y1 is the amount of the extraction solvent used in the step B-1)

a is less than 2.7, in terms of the extraction solvent,

X1 is the amount of water contained in the first concentration (meth) acrylic acid aqueous solution 103.

According to previously disclosed methods, a (meth) acrylic acid aqueous solution is discharged as a single stream at the bottom of the (meth) acrylic acid absorption tower 100, fed to the (meth) acrylic acid extraction tower 200, (Meth) acrylic acid extract solution 203, and the extract solution is distilled to recover (meth) acrylic acid.

However, the present inventors have found that when the concentration of the (meth) acrylic acid aqueous solution to be discharged is increased in order to improve the purification efficiency of the (meth) acrylic acid in the process of the conventional method for recovering the (meth) acrylic acid, (Or distillation) load in the subsequent purification (or distillation) step is increased when the concentration of the discharged (meth) acrylic acid solution is kept low in order to decrease the separation efficiency of the acrylic acid absorption tower 100 and increase the separation efficiency It is confirmed that there is a problem that must be done.

In addition, when hydrophilic components are separated from the weight residue discharged in the extraction step and used as the absorption solvent in the absorption process, when the solution is supplied to the upper end of the absorption column, the hydrophilic component is lost due to non-condensable gas discharged to the upper portion of the absorption column ) Acrylic acid in the reaction solution.

As a result of continuous research by the present inventors, it has been found that a stream having different concentration values is discharged from the side and bottom of the (meth) acrylic acid absorption tower 100, respectively, and the low- , The water is removed and then introduced into the distillation step together with the high concentration stream discharged from the bottom to reduce the load of the subsequent distillation step to increase the energy efficiency and to recycle the additional residual liquid component to a specific position of the absorption tower The efficiency of the absorption tower can be increased, and the present invention has been completed.

(Absorption process)

The method for recovering (meth) acrylic acid according to one embodiment of the present invention includes a step of dissolving a mixed gas (1) containing (meth) acrylic acid, organic by-products and water vapor produced by the synthesis reaction of (meth) (Meth) acrylic acid aqueous solution by contacting it with water in the absorber 100. In this specification, the absorption process refers to a process for obtaining an aqueous (meth) acrylic acid solution as described above in the (meth) acrylic acid absorption tower 100.

More specifically, the synthesis reaction of (meth) acrylic acid may be carried out by a method of oxidizing at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, and (meth) have.

At this time, the gas-phase oxidation reaction can be carried out under a gas-phase oxidation reactor and reaction conditions of a conventional structure. The catalyst in the gas-phase oxidation reaction may also be a conventional one, for example, catalysts disclosed in Korean Patent Nos. 0349602 and 037818 may be used.

The (meth) acrylic acid-containing mixed gas (1) produced by the gas-phase oxidation reaction may contain an unreacted starting compound, an intermediate (meth) acrolein, an inert gas, carbon dioxide, Byproducts (acetic acid, low boiling point byproduct, high boiling point byproduct, etc.).

This (meth) acrylic acid aqueous solution is obtained by supplying a mixed gas (1) containing (meth) acrylic acid to a (meth) acrylic acid absorption tower 100 and bringing it into contact with water as an absorption solvent ≪ / RTI >

The type of the (meth) acrylic acid absorption tower 100 may be determined in consideration of the contact efficiency between the mixed gas 1 and the absorption solvent. For example, a packed column type (meth) acrylic acid Absorption tower, or a multistage tray type (meth) acrylic acid absorption tower. The (meth) acrylic acid absorption tower of the filled column type is filled with a filler such as a rashing ring, a pall ring, a saddle, a gauze, a structured packing type, May be applied.

The mixed gas 1 may be supplied to the lower part of the (meth) acrylic acid absorption tower 100 and the absorption solvent containing water may be supplied to the (meth) acrylic acid absorption tower 100 in consideration of the efficiency of the absorption process. As shown in FIG.

The absorption solvent may include water such as tap water, deionized water, and the like, and may include circulating process water (for example, process water 201 recycled from the extraction process) introduced from another process. In addition, the absorption solvent may contain a small amount of organic by-products (for example, acetic acid) introduced from another process. However, considering the absorption efficiency of the (meth) acrylic acid, it is preferable that the organic solvent (notably the circulating water) supplied to the (meth) acrylic acid absorption tower 100 contains 15% by weight or less of organic by- .

On the other hand, the (meth) acrylic acid absorption tower 100 may have an internal pressure of about 1 to about 1.5 bar or an internal pressure of about 1 to about 1.3 bar, and an internal pressure of about 1 to about 1.5 bar, in consideration of the condensation conditions of (meth) acrylic acid and the water content depending on the saturated water vapor pressure, 50 to about 100, or about 50 to about 80. < RTI ID = 0.0 >

On the other hand, in the (meth) acrylic acid aqueous solution prepared through the absorption process, the concentration increases as the (meth) acrylic acid absorption tower 100 further absorbs the (meth) acrylic acid downward. In general, ) At the lowermost portion inside the acrylic acid absorption tower 100, a concentration of about 50 to about 80% by weight is formed.

According to an embodiment of the present invention, at this time, a (meth) acrylic acid aqueous solution 103 of a first concentration having a relatively low concentration is discharged to the side of the (meth) acrylic acid absorption tower 100, (Meth) acrylic acid aqueous solution 102 having a second concentration with a high concentration.

Specifically, the first concentration may be about 40 wt% or less, preferably about 30 wt% or less, or about 5 to about 30 wt%, and the second concentration may be about 60 wt% Preferably, it can be at least about 70 weight percent, or from about 70 to about 95 weight percent.

However, the present invention is not limited to the above-mentioned range. The present invention is not limited to the above-described range, and can be determined depending on the temperature and pressure inside the (meth) acrylic acid absorption tower 100, the operation conditions of the process, and the concentration of (meth) have.

The non-condensable gas 101 from which (meth) acrylic acid has been degassed is discharged to the upper end of the (meth) acrylic acid absorption tower 100.

The side of the (meth) acrylic acid absorption tower 100 refers to the side of the (meth) acrylic acid absorption tower 100 at the middle portion, that is, the uppermost portion of the (meth) When it is set at 100, it may mean a side portion at any point corresponding to about 40 to about 99, preferably about 30 to about 70, from the top to the bottom.

In the (meth) acrylic acid recovery method of this embodiment, the (meth) acrylic acid aqueous solution 103 discharged from the side portion and the (meth) acrylic acid aqueous solution 102 discharged at the lowermost portion are separately introduced into each of the following processes.

According to an embodiment of the present invention, at least a part of the non-condensable gas 101 discharged to the upper portion of the (meth) acrylic acid absorption tower 100 is an organic byproduct (especially, acetic acid) contained in the non-condensable gas 101, , And the remainder may be supplied to the waste gas incinerator and discarded.

That is, according to one embodiment of the present invention, a process of contacting the non-condensable gas 101 with an absorption solvent and recovering acetic acid contained in the non-condensable gas 101 may be performed.

The step of contacting the non-condensable gas 101 with the absorption solvent may be performed in the acetic acid absorption tower 150. At this time, for effective acetic acid absorption, the acetic acid absorption tower 150 can be operated at a pressure condition of about 1 to about 1.5 bar, preferably about 1 to about 1.3 bar, and a pressure of about 50 to about 100, Lt; RTI ID = 0.0 > 50 < / RTI > In addition, specific operating conditions of the acetic acid absorption tower 150 may be found in Korean Patent Publication No. 2009-0041355.

At this time, an acetic acid absorption solvent 151 for absorbing acetic acid is supplied to the upper part of the acetic acid absorption tower 150, and an aqueous solution 152 containing acetic acid is discharged to the lower part of the acetic acid absorption tower 150 . The acetic acid-containing aqueous solution 152 may be supplied to the upper portion of the (meth) acrylic acid absorption tower 100 and used again as an absorption solvent. In addition, the non-condensable gas 101 in which the acetic acid is deaerated can be recycled to the synthesis reaction process of (meth) acrylic acid.

As described above, when a relatively low concentration of the (meth) acrylic acid aqueous solution 103 is discharged directly from the side of the (meth) acrylic acid absorption tower 100, a relatively large amount of the water X1 is discharged together therewith, The amount (X2) of the water discharged to the lower part of the (meth) acrylic acid absorption tower 100 is inevitably reduced. Accordingly, the (meth) acrylic acid aqueous solution 102 It is possible to discharge it.

Generally, when the concentration of (meth) acrylic acid discharged from the (meth) acrylic acid absorption tower to the lower portion of the (meth) acrylic acid absorption tower is increased, the absorption efficiency of the (meth) The content of (meth) acrylic acid increases in the non-condensable gas discharged to the upper part of the (meth) acrylic acid absorption tower, resulting in loss of (meth) acrylic acid.

However, when the (meth) acrylic acid aqueous solution 103 is discharged directly from the side of the (meth) acrylic acid absorption tower 100 as in the present invention, the absorption of the (meth) acrylic acid absorption tower 100 (Meth) acrylic acid 102 discharged at the lowermost portion of the (meth) acrylic acid absorption tower 100 can be further increased and the separately discharged low-concentration (meth) acrylic acid aqueous solution 103 ) Can also be easily recovered through a simple extraction process to be described later.

According to an embodiment of the present invention, the (meth) acrylic acid aqueous solution 103 having a first concentration discharged to the side portion may have a concentration of about 10% by weight or more, To about 50% by weight, and it may be preferable to proceed under conditions satisfying the following formula (2).

&Quot; (2) "

0.01? X1 / (X1 + X2)? 0.7

In Equation (2)

X1 is the amount of water in the (meth) acrylic acid aqueous solution 103 of the first concentration,

X2 is the amount of water in the (meth) acrylic acid aqueous solution 102 of the second concentration.

In this case, X1 + X2 corresponds to the total amount of water discharged from the absorption process used in the present invention. In the conventional process for discharging only the lower single stream from the absorption tower, .

In the first concentration (meth) acrylic acid aqueous solution (103) and the second concentration (meth) acrylic acid aqueous solution (102), when the amount of the relative water discharged with the above- To minimize the amount of (meth) acrylic acid lost through the non-condensable gas 101 discharged into the non-condensing gas 101. The ratio of X1 to the total amount of water discharged from the absorption process may preferably be about 0.1 to about 0.7.

Further, when the amount of the relative water discharged to the side portion and the lower portion satisfies the above range, the process load is reduced in processes such as subsequent extraction or distillation for obtaining (meth) acrylic acid from the (meth) acrylic acid aqueous solution with high purity.

Specifically, when the amount of water (X1) contained in the side portion, that is, the first concentration (meth) acrylic acid aqueous solution 103 becomes relatively larger, a subsequent extraction process for extracting (meth) acrylic acid In this case, the use of the azeotropic solvent added to the distillation process is relatively reduced, the process load in the distillation process is reduced and the energy efficiency is increased. On the other hand, The purification efficiency in the distillation step is decreased, and the loss of acrylic acid is increased.

Conversely, when the amount of the water (X1) contained in the side portion, that is, the first concentration (meth) acrylic acid aqueous solution 103 is relatively small, the extraction solvent required in the extraction step for extracting (meth) acrylic acid In this case, the amount of the azeotropic solvent to be added in the distillation step is increased so that the efficiency of purifying acrylic acid in the distillation step is increased and the loss of acrylic acid can be reduced. However, The amount of water is reduced, so that the advantageous effect of the present invention, that is, the increase in the energy efficiency, can be reduced.

(Extraction process)

The method for recovering (meth) acrylic acid according to one embodiment is characterized in that the first concentration (meth) acrylic acid aqueous solution (103) discharged to the side of the (meth) acrylic acid absorption tower (100) (Meth) acrylic acid in contact with an extraction solvent (302) containing a hydrophobic organic solvent in the reaction vessel (200).

(Meth) acrylic acid aqueous solution 103 is brought into contact with the extraction solvent 302 in the (meth) acrylic acid extraction tower 200 to produce a (meth) acrylic acid extract (extract) 203 And raffinate, which lost a significant amount of (meth) acrylic acid.

In the (meth) acrylic acid extraction tower 200, the (meth) acrylic acid extract solution 203 which is a relatively light phase is obtained through the upper outlet, and the relatively heavy supernatant is recovered from the (meth) acrylic acid extraction tower 200, As shown in FIG.

The residual balance is present in a state in which a certain level of amount remains in the lower pressure zone of the (meth) acrylic acid extraction tower 200 before being discharged from the (meth) acrylic acid extraction tower 200, Methacrylic acid extraction tower 200 and a part thereof may be reused as a (meth) acrylic acid absorption solvent 201 for absorbing (meth) acrylic acid into the (meth) acrylic acid absorption tower 100 have.

Thus, most of the water contained in the (meth) acrylic acid aqueous solution can be removed by contacting the (meth) acrylic acid aqueous solution with the extraction solvent in the (meth) acrylic acid extraction tower 200. Accordingly, it is possible to reduce the burden of the subsequent step of the distillation step, and the energy efficiency of the entire process can be improved.

Further, by reducing the burden of the distillation process, the polymerization reaction of (meth) acrylic acid which may occur during distillation can be minimized, and the recovery efficiency of the (meth) acrylic acid can be further improved.

The extraction solvent 302 supplied to the (meth) acrylic acid extraction tower 200 may include a hydrophobic organic solvent and other organic by-products. For example, the extraction solvent 302 may include a circulating process It can be used every day.

Specifically, the extraction solvent is selected from the group consisting of benzene, toluene, xylene, n-heptane, cycloheptane, cycloheptene, 1- heptene, ethyl-benzene, methyl-cyclohexane, n-butyl acetate, isobutyl acetate, isobutyl acrylate, n-propyl acetate, isopropyl acetate, methyl isobutyl ketone, 2-methyl-1-heptene, 6-methyl- Methyl-1-heptene, 2-ethyl-1-hexene, ethylcyclopentane, 2-methyl-1-hexene, 2,3-dimethylpentane, 5-methyl-1-hexene, ), And isopropyl-butyl-ether (hereinafter referred to as " isopropyl " A it may include a hydrophobic organic solvent, and preferably renil benzene, toluene, or xylene.

The (meth) acrylic acid extraction tower 200 can be used without any particular limitation if it is a conventional extraction column according to a liquid-liquid contact method.

For example, a Karr type reciprocating plate column, a rotary-disk contactor, a Scheibel column, a Kuhni column, a spray extraction tower, a packed extraction column an extraction tower, a pulsed packed column, and the like.

Through the extraction process, the (meth) acrylic acid extractant 203 is discharged to the upper part of the (meth) acrylic acid extraction tower 200 and can be transported to the azeotropic distillation column 300 through the transfer line.

In the bottom of the (meth) acrylic acid extraction tower 200, the residual balance is discharged, and the hydrophilic component including water among the discharged residual liquid is recycled as described above to obtain a (meth) acrylic acid absorption tower 100) as the (meth) acrylic acid absorbing solvent 201.

Acrylic acid absorption column 201 may be supplied directly to the (meth) acrylic acid absorption tower 100 from the lower part of the (meth) acrylic acid extraction tower 200 when the (meth) acrylic acid absorption solvent 201 is used as the absorption solvent of the absorption tower, Is transferred to the phase separation tank 350 together with the azeotropic solvent contained in the upper discharge liquid 304 discharged to the upper portion of the azeotropic distillation column and then separated into the absorption solvent of the (meth) acrylic acid absorption tower 100 (Meth) acrylic acid absorption tower 100 in the lower part of the (meth) acrylic acid extraction tower 200, as described above, in the case of the present invention, , It is injected at a point corresponding to a height of 5 to 50% from the top of the absorption tower to the bottom.

(Meth) acrylic acid absorption tower 100 in a portion higher than the above-mentioned range, the non-condensable gas discharged to the upper portion of the absorption tower while the absorption solvent having a high concentration of (meth) The amount of (meth) acrylic acid that is lost through the polymerization reaction may increase.

In the case where the water is introduced into the (meth) acrylic acid absorption tower 100 at a portion lower than the above-mentioned range, the absorption solvent coming down from the top of the absorption tower comes into contact with the acrylic acid gas coming from the bottom, The absorption efficiency of the (meth) acrylic acid is greatly lowered in the absorption process, and the loss of the (meth) acrylic acid may be increased.

At this time, the extract may contain an extraction solvent, water, and organic by-products in addition to the target compound (meth) acrylic acid. According to this embodiment, in a steady state where stable operation is performed, the extract may contain about 2 to about 20 weight percent (meth) acrylic acid, about 78 to about 98 weight percent extraction solvent, about 0.01 to about 2 weight percent water, And residual organic byproducts.

Most of the water contained in the (meth) acrylic acid aqueous solution through the extraction step can be recovered as an additional residue. As most of the water is recovered in the extraction process, the operation load of the distillation process, which will be described later, can be reduced, and the energy consumption can be greatly reduced. As a result, the distillation conditions can be alleviated and the polymerization reaction of the (meth) acrylic acid can be minimized in the distillation step, thereby securing the operation stability and improving the recovery efficiency of the (meth) acrylic acid.

In the step of extracting the (meth) acrylic acid, the process is carried out under conditions satisfying the following expression (1).

[Equation 1]

Y1 = a x X1

In the above equation (1)

Y1 is the amount of the extraction solvent used in the step B-1)

a is less than 2.7, in terms of the extraction solvent,

X1 is the amount of water contained in the first concentration (meth) acrylic acid aqueous solution 103.

a is the ratio of the extraction solvent used for the amount of the extraction solvent to the amount of water supplied to the (meth) acrylic acid extraction tower 200, which may vary depending on the extraction solvent actually used, and about 2.7 , Preferably from about 1.5 to less than about 2.7. However, the present invention is not necessarily limited to this range, and it may be set differently in consideration of the kind of the extraction solvent used in the extraction process, the efficiency of the extraction process, and the process load in the distillation process described later .

That is, the weight ratio of the extraction solvent Y1 to the water X1 in the first concentration (meth) acrylic acid aqueous solution 103 supplied to the (meth) acrylic acid extraction tower 200 can proceed under a condition of less than about 2.7, About 1.5 or more and less than about 2.7.

When the amount of the extraction solvent used in the extraction process is limited to a certain range, the amount of the azeotropic solvent (Y2) to be added to the uppermost portion of the azeotropic distillation column 300 is increased. Therefore, the purification efficiency of the azeotropic distillation column 300 . The weight balance 201 discharged to the lower part of the (meth) acrylic acid extraction tower 200 is again supplied to the upper part of the (meth) acrylic acid absorption tower 100, that is, The amount of energy used in the azeotropic distillation column 300 is reduced as well as the water is discharged into the residual liquid without using any additional energy in the extraction column 200. [ can do.

By such a principle, it is possible to optimize the absorption efficiency in the (meth) acrylic acid absorption tower 100, the extraction efficiency in the (meth) acrylic acid extraction tower 200, and the purification efficiency in the azeotropic distillation column 300, The energy consumption can be reduced in the entire process.

Further, the higher the weight ratio of the extraction solvent to water in the (meth) acrylic acid aqueous solution, the higher the extraction efficiency in the (meth) acrylic acid extraction process 200. However, in the subsequent azeotropic distillation process, The amount of the azeotropic solvent separately supplied to the azeotropic distillation column 300 is reduced, so that the distillation efficiency is significantly lowered and the loss of (meth) acrylic acid on the azeotropic distillation column 300 may increase.

The weight balance obtained from the (meth) acrylic acid extraction tower 200 may be mostly composed of water, and may contain a part of (meth) acrylic acid which is not extracted and an organic by-product.

Specifically, according to an embodiment of the present invention, the weight balance may contain a relatively high (meth) acrylic acid concentration of about 10% by weight or less, or about 3% by weight to about 10% by weight, The loss of (meth) acrylic acid can be minimized since it is re-introduced into the absorption solvent at about 5 to about 50%

(Distillation process)

The method for recovering the (meth) acrylic acid according to the embodiment of the present invention is characterized in that the (meth) acrylic acid extract solution 203 and the (meth) acrylic acid aqueous solution 102 of the second concentration discharged in the step C) (300) to obtain (meth) acrylic acid.

The solvent to be applied to the azeotropic distillation method is preferably a hydrophobic azeotropic solvent which can achieve an azeotropic ratio with water and acetic acid and does not have an azeotropic ratio with (meth) acrylic acid. And, it is preferred that the hydrophobic azeotropic solvent has a boiling point lower than that of (meth) acrylic acid (e.g., a boiling point of about 120 or less, or about 10 to about 120, or about 50 to about 120).

Specifically, the hydrophobic azeotropic solvent is selected from the group consisting of benzene, toluene, xylene, n-heptane, cycloheptane, cycloheptene, 1- ethyl-benzene, methyl-cyclohexane, n-butyl acetate, isobutyl acetate, isobutyl acrylate, isobutyl acrylate, n-propyl acetate, isopropyl acetate, methyl isobutyl ketone, 2-methyl-1-heptene, 6-methyl Methyl-1-heptene, 2-ethyl-1-hexene, ethylcyclohexyl, But are not limited to, ethylcyclopentane, 2-methyl-1-hexene, 2,3-dimethylpentane, 5-methyl- hexene and isopropyl-butyl-ether. Every day for at least one and, preferably, may be benzene, toluene, xylene or renil.

According to one embodiment of the present invention, the (meth) acrylic acid extract liquid 203 supplied from the above-described extraction process is supplied to the azeotropic distillation column 300 through the transfer line.

The (meth) acrylic acid extractant 203 may be added to the azeotropic distillation column 300 in an amount of about 25 to about 75% from the uppermost end to the lower end of the azeotropic distillation column 300 so that efficient distillation can be performed. , It is preferable that the solution is supplied in one stage corresponding to about 25 to about 50%.

The (meth) acrylic acid extract solution 203 supplied to the azeotropic distillation column 300 contains (meth) acrylic acid and the extraction solvent Y1 used in the preceding extraction process, and considering the production efficiency according to the continuous process , And the azeotropic solvent is preferably the same as the extraction solvent in the above extraction step.

That is, when the inside of the azeotropic distillation column 300 is appropriately heated, the extraction solvent Y1 contained in the (meth) acrylic acid extract solution 203 and the azeotropic solvent Y2 introduced from the upper portion of the distillation column 300, The azeotropic distillation can be carried out together with water and acetic acid fed to the feed end of the feeder 300.

According to an embodiment of the present invention, it is preferable that the azeotropic distillation process is performed under conditions satisfying the following equation (3).

&Quot; (3) "

Y = b x X2

In Equation (3)

Y is the amount of azeotropic solvent used in step D)

b is the void ratio,

X2 is the amount of water contained in the second concentration (meth) acrylic acid aqueous solution 102.

In the extraction process of the previous (meth) acrylic acid extraction column 200, most of the water is removed and the amount of water contained in the extract is very small, so that water supplied to the distillation column is contained in the second concentration (meth) acrylic acid aqueous solution 102 (X2).

b is an azeotropic ratio of the amount of the azeotropic solvent to the amount of water (X2) to be supplied to the azeotropic distillation column 300, which may vary depending on the azeotropic solvent actually used. For the efficiency of azeotropic distillation, , Preferably about 5 or more, and more preferably about 5.5 to about 8.5. However, the present invention is not necessarily limited to this range. As described above, the kind of the azeotropic solvent used in the distillation process, The efficiency of the distillation process, the process load, and the process load in the previous extraction process.

Through such an azeotropic distillation step, the components other than (meth) acrylic acid in the (meth) acrylic acid extract solution 203 and the second concentration of the (meth) acrylic acid aqueous solution 102 discharged in the step C) (304), and the (meth) acrylic acid is discharged to the bottom (303).

At this time, the upper discharge liquid 304 of the azeotropic distillation column 300 may be supplied to the phase separation tank 350 and reused after a predetermined treatment. Here, the phase separation tank 350 is a device for separating a liquid phase that is not mixed with each other by gravity or centrifugal force, and a relatively light liquid (for example, an organic phase) is supplied to the upper portion of the phase separation tank, , Water phase) can be recovered to the lower part of the phase separation tank.

In one example, the upper effluent liquid 304 of the azeotropic distillation column 300 can be separated into an aqueous phase containing an organic phase and a water phase comprising a solvent in the phase separation tank 350.

The separated organic phase 351 may be supplied to the upper end of the azeotropic distillation column 300 and used as an azeotropic solvent 301 and at least a portion of the organic phase 351 may be supplied to the (meth) acrylic acid extraction column 200 Can be used as the extraction solvent 302.

According to an embodiment of the present invention, it is preferable that the azeotropic distillation process is performed under conditions satisfying the following equations (4) and (5).

&Quot; (4) "

Y = Y1 + Y2

&Quot; (5) "

Y2> Y1

In the above equations (4) and (5)

Y is the total amount of azeotropic solvent used in the step D)

Y1 is the amount of the extraction solvent used in the step B-1)

And Y2 is the amount of azeotropic solvent added from above the azeotropic distillation column 300 in the step D).

As described above, it is preferable to use the same azeotropic solvent (Y2) in addition to the extraction solvent (Y1), which is used in the present invention, And the azeotropic solvent Y2 separately added are separated into an organic phase through the treatment in the phase separation tank 350 described above and reused because of extraction and azeotropic distillation. The amount is the same as the total amount (Y) of the azeotropic solvent used in the azeotropic distillation stage of D), which is added separately in the azeotropic distillation process of the extraction solvents (Y1) and D) used in the extraction process in step B-1) And the azeotropic solvent (Y2).

At this time, the amount of the azeotropic solvent (301, Y2) separately injected in the azeotropic distillation process among the organic phases (351, Y) separated through the treatment in the phase separation tank 350 described above is circulated to the extraction process, Is preferably larger than the amount of the extraction solvent (302, Y1) flowing into the azeotropic distillation column (300) together with the (meth) acrylic acid extract solution (203).

The amount of the azeotropic solvent 301 and Y2 separately introduced into the upper portion of the azeotropic distillation column 300 is smaller than the amount of the extraction solvent 302 and Y1 flowing into the azeotropic distillation column 300 together with the (meth) acrylic acid extract solution 203 The amount of the (meth) acrylic acid contained in the upper discharge liquid 304 discharged to the upper portion of the azeotropic distillation column 300 increases and the efficiency of the azeotropic distillation may be greatly reduced.

On the other hand, the (meth) acrylic acid aqueous solution is passed through the (meth) acrylic acid absorption tower 100, the (meth) acrylic acid extraction tower 200 and the azeotropic distillation tower 300, At least some of which may form dimers or oligomers. In order to minimize the polymerization of such (meth) acrylic acid, a conventional polymerization inhibitor may be added to the azeotropic distillation column 300.

The lower effluent 303 of the azeotropic distillation column 300 may contain, in addition to (meth) acrylic acid, a high-boiling by-product such as a polymer of (meth) acrylic acid, a polymerization inhibitor, or the like. Accordingly, if necessary, a step of supplying the lower effluent of the azeotropic distillation column 300 to the high boiling point byproduct separation column 400 may be further performed to separate the high boiling point byproducts contained in the lower effluent 303 have.

The recovered crude (meth) acrylic acid (CAA) through the above process can be obtained as (meth) acrylic acid (HPAA) of higher purity through an additional crystallization process. At this time, the high boiling point byproduct separation process, the crystallization process, and the like can be performed under ordinary conditions, so the process conditions and the like are not specifically limited.

In such a (meth) acrylic acid recovery method, each of the above-described steps can be carried out organically and continuously. In addition to the above-described steps, processes that can be conventionally performed before, after, or simultaneously with each step can be further included and operated.

Such a process may be carried out through an apparatus composed of a (meth) acrylic acid absorption tower 100, a (meth) acrylic acid extraction tower 200, and an azeotropic distillation column 300.

More specifically, the apparatus comprises a (meth) acrylic acid absorption tower 100; (Meth) acrylic acid aqueous solution (103) discharged from the side of the (meth) acrylic acid absorption tower (100) with an extraction solvent containing a hydrophobic organic solvent to extract (meth) acrylic acid An acrylic acid extraction tower 200; Distilling the (meth) acrylic acid aqueous solution 203 and the second concentration of the (meth) acrylic acid aqueous solution 102 discharged from the lowermost portion of the (meth) acrylic acid absorption tower 100 to obtain (meth) acrylic acid ) Acrylic acid azeotropic distillation column (300).

The (meth) acrylic acid absorption tower 100 may be a packed column type (meth) acrylic acid absorption tower, a multistage tray type, and the (meth) acrylic acid absorption The tower may be filled with a filler such as a rashing ring, a pall ring, a saddle, a gauze, or a structured packing.

Particularly, in the (meth) acrylic acid absorption tower 100 of (meth) acrylic acid of the embodiment, the first concentration discharging portion corresponds to about 40 to about 99% from the top to the bottom of the (meth) acrylic acid absorption tower 100 Or at any other point in time.

(Meth) acrylic acid absorption tower 100 can be connected to the (meth) acrylic acid extraction tower 200 through the side first concentration (meth) acrylic acid aqueous solution 103 transfer line . The (meth) acrylic acid extraction tower 200 may be connected to the azeotropic distillation column 300 through a transfer line of the (meth) acrylic acid extract liquid 203, and the (meth) acrylic acid absorption tower 100 may be connected to the (Meth) acrylic acid aqueous solution (102) transfer line.

The lower part of the (meth) acrylic acid extraction column 200 is connected to the 5 to 50% part from the upper part of the (meth) acrylic acid absorption tower through the transfer line 201, As shown in FIG.

As the (meth) acrylic acid extraction tower 200, a conventional (meth) acrylic acid extraction tower 200 according to a liquid-liquid contact method can be used without any particular limitation. (Meth) acrylic acid extraction column 200 may be a Karr type reciprocating plate column, a rotary-disk contactor, a Scheibel column, a Kuhni column, a spray (Meth) acrylic acid extraction tower, a packed extraction tower, a pulsed packed column, and the like.

The solvent recovery column and the azeotropic distillation column 300 are packed or packed with a packed column or a multi-column column, preferably a sieve tray column and a dual flow tray column, .

In addition, the (meth) acrylic acid recovery apparatus according to the present invention may have a conventional structure in the technical field of the present invention.

Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

<Examples>

( Mat Acrylic acid absorption process

Example  One

(Meth) acrylic acid absorption tower (100) comprising an absorption section at the upper part and a cooling section at the lower part, and a heat exchanger for cooling the lower condensate to the (meth) acrylic acid absorption tower ).

The absorption section was composed of 35 stages with an inner diameter of 70.6 cm and a sieve tray including down comers at intervals of 7 cm.

The cooling section immediately below the absorption section was composed of four stages with an inner diameter of 100 cm, an aperture ratio of 17%, and a hole ID of 3 mm, with a dual flow tray spaced by 10 cm.

The liquid condensed in the lower part of the (meth) acrylic acid absorption tower 100 is cooled while passing through the indirect heat exchanger and re-introduced into the uppermost part of the cooling section of the (meth) acrylic acid absorption tower 100 (the upper end of the dual flow tray) The temperature of the top of the (meth) acrylic acid absorption tower 100 was kept constant.

The mixed gas (1) containing acrylic acid contained 100 l / min N ₂ heated to a high temperature of 800 ° C and 46.3 g / min including 60.77 wt%, 1.83 wt% and 36.44 wt% of acrylic acid, Was prepared as a diluted gas at 165 ° C. and then introduced from the bottom of the (meth) acrylic acid absorption tower 100.

At the uppermost stage of the (meth) acrylic acid absorption tower 100, the absorption water having the concentrations of acrylic acid and acetic acid of 1.86 and 9.16% by weight was fed at 11.19 g / min. Then, the weight balance of the extracting column 200 having 3.49% and 4.44% by weight of acrylic acid and acetic acid, respectively, was fed into the eighth sieve tray from the uppermost stage together with the absorption solvent 201 at 7.12 g / min.

From the top of the (meth) acrylic acid absorption tower 100, the first concentration acrylic acid aqueous solution of 8.99 g / min was discharged from the 23rd sieve tray using a pump. In the first concentration acrylic acid aqueous solution, the concentrations of acrylic acid and acetic acid were 17.48% by weight and 3.35% by weight, respectively.

The temperature of the uppermost stage of the (meth) acrylic acid absorption tower 100 was kept constant at 64.5 ° C. and the temperature of the bottom of the (meth) acrylic acid absorption tower 100 was maintained at a constant level, The second concentration aqueous acrylic acid solution was discharged.

After the (meth) acrylic acid absorption tower 100 was operated for about 10 hours, the discharge flow rate of the lower liquid of the (meth) acrylic acid absorption tower 100, that is, the flow rate of the second concentration acrylic acid aqueous solution was 33.73 g / The concentrations of acetic acid were 78.0% by weight and 2.37% by weight, respectively.

The non-condensable gas 101 discharged to the top of the (meth) acrylic acid absorption tower 100 was discharged at 146.92 g / min. The concentration of acrylic acid in the discharged gas was 0.48 wt%, the ratio of H ₂ O / N ₂ The temperature of the second aqueous acrylic acid solution discharged was 76.3 ° C, and the uppermost and lowermost pressures of the (meth) acrylic acid absorption tower 100 were 114 mbar and 163 mbar, respectively.

The amount of water contained in the first concentration acrylic acid aqueous solution and the amount of water contained in the second concentration acrylic acid aqueous solution were in the ratio of 53:47.

( Mat ) Acrylic acid extraction process

Example  2

(Meth) acrylic acid extraction tower 200 was constructed using a Karr type reciprocating plate column having an inner diameter of 22 mm and a total of 56 stages.

The first concentration acrylic acid aqueous solution (acrylic acid: 21.06% by weight, acetic acid: 4.15% by weight) was introduced at the first stage at the top of the (meth) acrylic acid extraction tower 200 at 35.9 g / min.

The extraction solvent used was a part of the reflux stream containing toluene obtained as the organic phase 351 in the upper effluent of the azeotropic distillation column 300. The extraction solvent contained 0.28% by weight of acrylic acid, 0.5% by weight of acetic acid, Respectively.

The extraction solvent was introduced at 59.48 g / min through the 56th stage which is the bottom end of the (meth) acrylic acid extraction tower 200.

The extract solution was discharged at a flow rate of 66.67 g / min onto the (meth) acrylic acid extraction tower 200 in a steady state. The extract solution contained 10.1 wt% of acrylic acid, 0.75 wt% of acetic acid, 0.66 wt% of water, .

A residual liquid containing 3.49 wt% of acrylic acid, 4.36 wt% of acetic acid, and a residual amount of water was discharged to the lower portion of the (meth) acrylic acid extraction tower 200.

In the operation of the (meth) acrylic acid extraction tower 200, the water removal rate to the first concentration acrylic acid aqueous solution was 98.4%, and the acrylic acid extraction ratio was 87.0%.

(A) of the extraction solvent / water charged into the (meth) acrylic acid extraction tower 200 during operation of the (meth) acrylic acid extraction column 200 was 2.18.

As described above, the weight balance of the extracting column 200 having acrylic acid and acetic acid of 3.49 and 4.44 weight%, respectively, was absorbed into the eighth sieve tray from the top of the (meth) acrylic acid absorption tower 100 at 7.12 g / 201).

Comparative Example  One

In Example 2, the additional residual liquid 201 discharged to the lower part of the (meth) acrylic acid extraction tower 200 was sent to the phase separation tank 350 and phase separated. The concentration of acrylic acid in the aqueous phase (352) was 2.45% by weight, which was fed to the top of the (meth) acrylic acid absorption tower. The process was carried out in the same manner as in Examples 1 and 2 except for this.

After the (meth) acrylic acid absorption tower 100 was operated for about 10 hours, the discharge flow rate of the lower liquid of the (meth) acrylic acid absorption tower 100, that is, the flow rate of the second concentration acrylic acid aqueous solution was 42.69 g / The concentrations of acetic acid were 67.95% by weight and 2.65% by weight, respectively.

The non-condensable gas 101 discharged to the top of the (meth) acrylic acid absorption tower 100 was discharged at 147.36 g / min. The concentration of acrylic acid in the discharged gas was 0.538% by weight, the ratio of H ₂ O / N ₂ (Meth) acrylic acid absorption tower 100 was 16.5: 100, the temperature of the second aqueous acrylic acid solution discharged was 74.6 占 폚, and the uppermost and lowermost pressures of the (meth) acrylic acid absorption tower 100 were 122 mbar and 170 mbar, respectively.

When the concentration of (meth) acrylic acid in the residual liquid discharged to the lower part of the (meth) acrylic acid extraction tower 200 is high as in the example of the present invention, from the top of the (meth) acrylic acid absorption tower 100 to the bottom It can be clearly confirmed that the content of acrylic acid contained in the non-condensable gas discharged to the upper portion can be lowered in the case of charging into the portion of about 5 to 50% than in the case of charging at the uppermost portion.

In this case, the amount of the extraction solvent (Y1) used in the (meth) acrylic acid extraction tower 200 is small, so that the amount of the extraction solvent contained in the extraction liquid is reduced. As a result, It can be clearly confirmed that the purification efficiency in the azeotropic distillation column 300 can be kept high as the amount of the supplied azeotropic solvent Y2 increases.

That is, the water contained in the first concentration (meth) acrylic acid aqueous solution discharged through the side of the (meth) acrylic acid absorption tower 100 is removed without using any energy in the (meth) acrylic acid extraction tower 200, It is possible to minimize the loss of acrylic acid in the distillation column 300 and the (meth) acrylic acid absorption tower, and it is clear that the purification efficiency and the energy consumption can be greatly reduced in the purification process.

1: Mixed gas
100: (meth) acrylic acid absorption tower
101: Non-condensable gas in which (meth) acrylic acid is deaerated
102: aqueous solution of (meth) acrylic acid in a second concentration
103: A solution of a (meth) acrylic acid aqueous solution
150: Acetic acid absorption tower
151: Acetic acid absorption solvent
152: aqueous solution containing acetic acid
200: (meth) acrylic acid extraction tower
201: (meth) acrylic acid absorption solvent
203: (meth) acrylic acid extract solution
300: azeotropic distillation tower
301: azeotropic solvent added separately to the top of the azeotropic distillation column
302: Extraction solvent
303: Aeration column bottom of the azeotropic distillation column
304: Aromatic distillation column top discharge liquid
350: phase separation tank
351: Organic phase separated from the phase separation tank
352: Water phase separated from the phase separation tank, (meth) acrylic acid absorption solvent
400: High boiling point byproduct separation tower

Claims (9)

A) contacting a mixed gas comprising (meth) acrylic acid, organic by-products and water vapor with water in a (meth) acrylic acid absorption tower to form an aqueous (meth) acrylic acid solution;
B) discharging a first concentration of (meth) acrylic acid aqueous solution at the side of the (meth) acrylic acid absorption tower;
C) discharging a second concentration of (meth) acrylic acid aqueous solution at the lowermost portion of the (meth) acrylic acid absorption tower;
(B-1) extracting (meth) acrylic acid by bringing a first concentration of a (meth) acrylic acid aqueous solution discharged to the side into an extraction solvent containing a hydrophobic organic solvent in a (meth) acrylic acid extraction tower;
D) distilling the (meth) acrylic acid extract solution extracted in the step (B-1) and the aqueous solution of the second concentration of the (meth) acrylic acid discharged in the step (C) through an azeotropic distillation process to obtain (meth) acrylic acid step; And
E) recycling the raffinate of step B-1) into the absorption water of step A)
In the step E), the weight balance is introduced as absorbing water at a point corresponding to a height of 5 to 50% from the top of the absorption tower to the bottom,
Wherein the first concentration is lower than the second concentration in the concentration of (meth) acrylic acid,
A method for recovering (meth) acrylic acid which satisfies the following formula (1):
[Equation 1]
Y1 = a x X1
In the above equation (1)
Y1 is the amount of the extraction solvent used in the step B-1)
a is less than 2.7, in terms of the extraction solvent,
X1 is the amount of water contained in the first concentration (meth) acrylic acid aqueous solution.
The method according to claim 1,
Wherein the (meth) acrylic acid aqueous solution discharged at the first concentration is discharged at a point corresponding to a height of 40 to 99% from the uppermost portion of the (meth) acrylic acid absorption tower to the lower portion thereof.
The method according to claim 1,
Wherein the step of making the (meth) acrylic acid aqueous solution is carried out at a pressure of 1 to 1.5 bar and a temperature of 50 to 100.
The method according to claim 1,
Wherein the (meth) acrylic acid aqueous solution of the first concentration contains not more than 40% by weight of (meth) acrylic acid.
The method according to claim 1,
Wherein said (meth) acrylic acid aqueous solution of said second concentration comprises at least 60 wt% of (meth) acrylic acid.
The method according to claim 1,
The (meth) acrylic acid aqueous solution of the first concentration discharged to the side portion is discharged at a rate of 10% by weight to 50% by weight relative to the aqueous solution of the second concentration of the (meth) acrylic acid discharged at the lowermost portion. Recovery method.
The method for recovering (meth) acrylic acid according to claim 1, which satisfies the following formula (2):
&Quot; (2) &quot;
0.01? X1 / (X1 + X2)? 0.7
In Equation (2)
X1 is the amount of water in the (meth) acrylic acid aqueous solution of the first concentration,
X2 is the amount of water in the (meth) acrylic acid aqueous solution of the second concentration.
The method for recovering (meth) acrylic acid according to claim 1, which satisfies the following formula (3):
&Quot; (3) &quot;
Y = b x X2
In Equation (3)
Y is the amount of azeotropic solvent used in step D)
b is the void ratio,
X2 is the amount of water contained in the second concentration (meth) acrylic acid aqueous solution.
The method according to claim 1,
The extraction solvent used in the step B-1) and the azeotropic solvent used in the step D) are the same and satisfy the following formulas 4 and 5:
&Quot; (4) &quot;
Y = Y1 + Y2
&Quot; (5) &quot;
Y2> Y1
In the above equations (4) and (5)
Y is the total amount of azeotropic solvent used in the step D)
Y1 is the amount of the extraction solvent used in the step B-1)
And Y2 is the amount of the azeotropic solvent added in the step D).

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