KR101642504B1 - Process for continuous recovering (meth)acrylic acid and apparatus for the process - Google Patents

Abstract

The present invention relates to a continuous recovery method of (meth) acrylic acid and a device used in the method. The continuous recovery method and apparatus of (meth) acrylic acid according to the present invention makes it possible to operate a more stable and stable continuous process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a continuous recovery method of a (meth) acrylic acid,

The present invention relates to a continuous recovery method of (meth) acrylic acid and a device used in the method.

(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 Methane A reaction product mixture gas 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 reaction is obtained.

The (meth) acrylic acid-containing mixed gas is contacted with an absorption solvent in a (meth) acrylic acid absorption tower 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 a (meth) acrylic acid aqueous solution obtained from the (meth) acrylic acid absorption tower, a method of azeotropically distilling a distillation column using a hydrophobic solvent is known. Alternatively, a method is known in which an aqueous (meth) acrylic acid solution is supplied to an extraction column to obtain an (meth) acrylic acid extract and a residual liquid having a reduced water content, and the extracted liquid is distilled to reduce energy consumption.

On the other hand, due to the characteristics of the continuous process for the recovery of (meth) acrylic acid, the possibility that a solvent or foreign substance used in the (meth) acrylic acid extraction process or distillation process is introduced into the (meth) acrylic acid absorption process or the (meth) I can not exclude it. In this case, the (meth) acrylic acid synthesis reactor, the catalyst, or the absorption tower may be contaminated by the solvent or foreign matter, and the recovery efficiency may be lowered, and serious safety problems may be caused.

The present invention provides a continuous recovery method of (meth) acrylic acid which enables the safe and stable continuous operation of the process by preventing the extraction solvent or the like from flowing into the (meth) acrylic acid absorption process or the like in the continuous recovery process of the (meth) acrylic acid .

The present invention also provides an apparatus for continuous recovery of the (meth) acrylic acid.

According to the present invention,

An absorption step of obtaining a (meth) acrylic acid aqueous solution by bringing a mixed gas containing (meth) acrylic acid, organic by-products and water vapor produced by the synthesis reaction of (meth) acrylic acid into contact with water; (Meth) acrylic acid aqueous solution obtained through the absorption process is contacted with an extraction solvent in an extraction tower to obtain an (meth) acrylic acid extract solution through an upper outlet of the extraction tower, and an additional residue An extraction step of obtaining; And a distillation step of distilling a feed containing the (meth) acrylic acid extract to obtain (meth) acrylic acid;

Separating the residual balance obtained through the lower outlet of the extraction column into an organic phase and an aqueous phase in a phase separation tank in the extraction step, feeding the organic phase to the distillation step, and supplying the aqueous phase to the absorption step Methacrylic acid is continuously recovered.

According to the present invention, at least a part of the organic phase by phase separation of the residual balance can be supplied to the extraction step.

According to the present invention, a method of filtering the residual balance obtained through the extraction process to remove scum contained in the residual balance, and separating the filtrate obtained by the filtration into an organic phase and a water phase .

According to the present invention,

The absorption process; (Meth) acrylic acid aqueous solution obtained through the absorption process is contacted with an extraction solvent in an extraction column to obtain an (meth) acrylic acid extract solution through an upper outlet of the extraction column, and the An extraction step of obtaining an additional balance; And a distillation step of distilling a mixture containing at least a part of the (meth) acrylic acid aqueous solution obtained through the absorption process and the (meth) acrylic acid extract obtained through the extraction step to obtain (meth) acrylic acid .

On the other hand, according to the present invention,

(Meth) acrylic acid absorption tower (100) for obtaining a (meth) acrylic acid aqueous solution by contacting water with a mixed gas containing (meth) acrylic acid, an organic by-product, and water vapor produced by a synthesis reaction of (meth) acrylic acid;

(Meth) acrylic acid aqueous solution obtained from the absorption tower 100 is contacted with the extraction solvent by contacting the absorption tower 100 with the (meth) acrylic acid aqueous solution transfer line 102, A (meth) acrylic acid extraction tower 200 to obtain an extract and an additional residue;

(Meth) acrylic acid extract solution obtained from the extraction column 200 is distilled to obtain (meth) acrylic acid by a distillation column (distillation column) 200 connected to the extraction column 200 by a (meth) acrylic acid extract liquid transfer line 203, 300); And

A phase separation tank 350 connected to the extraction tower 200 by an additional balance transfer line 235 for separating the residual balance obtained from the extraction tower 200 into an organic phase and an aqueous phase,

(Meth) acrylic acid.

According to the present invention, the continuous recovery apparatus for (meth) acrylic acid comprises a step of removing the scum contained in the added residual liquid by filtering the residual residual liquid obtained from the extraction tower 200, And a filtration system 250 for supplying the purified water to the phase separation tank 350 through the filter 253.

The method and apparatus for continuous recovery of (meth) acrylic acid according to the present invention prevent the extraction solvent and the like from being introduced into the (meth) acrylic acid absorption process or the synthesis reaction process, thereby enabling a safer and more stable continuous process operation.

1 schematically shows a method and an apparatus for continuously recovering (meth) acrylic acid according to a comparative example of the present invention.
Figs. 2 to 5 schematically show a method and apparatus for continuous recovery of (meth) acrylic acid according to embodiments of the present invention, respectively.

Hereinafter, the continuous recovery method and recovery apparatus of (meth) acrylic acid according to embodiments of the present invention will be described.

Prior to this, unless expressly stated throughout the present specification, several terms are defined with the following meanings.

First, '(meth) acrylic acid' can be used to mean acrylic acid, methacrylic acid or a mixture thereof.

In addition, '(meth) acrylic acid-containing mixed gas' refers to a mixed gas that can be generated when (meth) acrylic acid is synthesized 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. (Meth) acrylic acid, an unreacted raw material compound, (meth) acrolein, an inert gas, carbon monoxide, carbon dioxide, water vapor, and various organic byproducts (acetic acid, low boiling point byproduct, high boiling point byproduct, etc.) May be included. Herein, the water-soluble suspension formed by the organic by-products is referred to as 'scum'.

The '(meth) acrylic acid aqueous solution' can be obtained as an aqueous solution containing (meth) acrylic acid, for example, by bringing the (meth) acrylic acid-containing mixed gas into contact with water as an absorption solvent.

And, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. And, the singular forms used herein include plural forms unless the phrases expressly have the opposite meaning. Also, as used herein, the term " comprises " embodies specific features, regions, integers, steps, operations, elements or components, and does not exclude the presence of other specified features, regions, integers, steps, operations, elements, It does not.

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.

On the other hand, in the continuous recovery method of (meth) acrylic acid including the absorption process of the (meth) acrylic acid, the extraction process and the distillation process, the solvent used in the extraction process or the distillation process (for example, toluene, It is impossible to exclude the possibility that a foreign substance such as benzene or the like is introduced into the absorption process or the (meth) acrylic acid synthesis reaction process. If the solvent or foreign matter is introduced into the absorption process or the synthesis reaction process , The absorption tower, the reactor, the reaction catalyst and the like may be contaminated, the recovery efficiency of the (meth) acrylic acid may be reduced, and serious safety problems may be caused.

In this connection, in the case of the continuous recovery method of general (meth) acrylic acid including the absorption process of (meth) acrylic acid, the extraction process and the distillation process, as shown in FIG. 1, A certain amount of residual balance is settled and phase separated into organic phase and water phase. Since the amount of weight residue generated by the extraction and the amount of the residual balance discharged through the lower outlet of the extraction column are maintained substantially equal to each other, the amount of the remaining weight remaining in the lower portion of the extraction tower 200, This is maintained at a certain level. The water phase may be supplied to the absorber 100 through the additional balance transfer line 201 and used as the absorption water, assuming that the height of the interface is maintained at a constant level.

1, the interface between the organic phase and the water phase due to the residual balance at the bottom of the extraction column 200 can not be maintained at a constant height, and an excessive amount of the organic phase is supplied to the absorption tower 100 together with the water phase The absorption tower 100 is contaminated by the extraction solvent contained in the organic phase and the absorption efficiency is lowered. In addition, in a severe case, the extraction solvent flows into the (meth) acrylic acid synthesis reactor and causes serious safety problems. .

In order to solve this problem, the inventors of the present invention have found that, in the course of repeated studies to overcome such problems, the weight balance obtained through the extraction process is not directly supplied to the absorption process, (Meth) acrylic acid can be maintained when the organic phase is fed to the distillation process and the water phase is fed to the absorption process, it is possible to fundamentally block the introduction of excess organic phase into the absorption process . Particularly, in the case of the above method, it is possible to operate the continuous process safely and stably even if the interface between the organic phase and the water phase fails to be maintained in the residual balance portion under the extraction tower.

( Mat ) Continuous recovery method of acrylic acid

According to an embodiment of the present invention,

An absorption step of obtaining a (meth) acrylic acid aqueous solution by bringing a mixed gas containing (meth) acrylic acid, organic by-products and water vapor produced by the synthesis reaction of (meth) acrylic acid into contact with water; (Meth) acrylic acid aqueous solution obtained through the absorption process is contacted with an extraction solvent in an extraction tower to obtain an (meth) acrylic acid extract solution through an upper outlet of the extraction tower, and an additional residue An extraction step of obtaining; And a distillation step of distilling a feed containing the (meth) acrylic acid extract to obtain (meth) acrylic acid;

Separating the residual balance obtained through the lower outlet of the extraction column into an organic phase and an aqueous phase in a phase separation tank in the extraction step, feeding the organic phase to the distillation step, and supplying the aqueous phase to the absorption step Methacrylic acid is continuously recovered.

Basically, the continuous recovery method of (meth) acrylic acid includes an absorption step for obtaining an aqueous (meth) acrylic acid solution, an extraction step for the aqueous solution, and a distillation step. Particularly, the continuous recovery method of (meth) acrylic acid is characterized in that in the extraction step, the residual balance obtained through the lower outlet of the extraction column is phase separated from the organic phase and water phase in the phase separation tank, It is possible to fundamentally block the introduction into the process.

Hereinafter, each process that can be included in the method of the above embodiments will be described with reference to FIGS. 2 to 4. FIG.

I. Absorption Process

First, a continuous recovery method of (meth) acrylic acid according to an embodiment includes a step of bringing a (meth) acrylic acid, an organic by-product, and a gas mixture produced by the synthesis reaction of (meth) An absorption process to obtain an aqueous acrylic acid solution is included.

The absorption process is a step for obtaining an aqueous (meth) acrylic acid solution, which can be obtained according to a conventional method in the technical field of the present invention.

As a non-limiting example, the synthesis reaction of (meth) acrylic acid may be carried out by oxidation reaction of at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, t-butylene and (meth) . ≪ / RTI >

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, and preferably the catalysts disclosed in Korea Patent No. 0349602 and No. 037818 can be used.

The (meth) acrylic acid-containing mixed gas produced by the gas-phase oxidation reaction may contain an unreacted starting compound, an intermediate (meth) acrolein, other inert gases, carbon dioxide, water vapor, and various organic by- , Low boiling point byproducts, high boiling point byproducts, etc.).

According to one embodiment, the (meth) acrylic acid-containing mixed gas (1) may be obtained in the form of a (meth) acrylic acid aqueous solution by being supplied to the (meth) acrylic acid absorption tower (100) and coming into contact with water as an absorption solvent.

Here, the type of the (meth) acrylic acid absorption tower 100 can be determined in consideration of the contact efficiency between the mixed gas (1) and the absorbing solvent. As a non-limiting example, the (meth) acrylic acid absorption tower 100 may be a packed tower or a multistage tray tower. Here, the filling column may have a filler such as a rashing ring, a pall ring, a saddle, a gauze, and a structured packing.

Meanwhile, the mixed gas 1 may be supplied to the lower part of the absorption tower 100 in consideration of the absorption efficiency, and the absorption solvent may be supplied to the upper part of the absorption tower 100.

The absorbing solvent may be water such as tap water, deionized water, or the like, and may include a circulating process water introduced from another process. Accordingly, the absorbing solvent may contain trace amounts of organic by-products (e.g., acetic acid) introduced from other processes. According to one embodiment, the absorption solvent supplied to the absorber 100 may contain 3 to 15% by weight of organic byproducts. That is, in consideration of the absorption efficiency of (meth) acrylic acid, it is preferable that the absorption solvent (particularly the circulating process water) supplied to the absorption tower 100 contains 15% by weight or less of organic byproducts.

The (meth) acrylic acid absorption tower 100 can be operated at an internal pressure of 1 to 1.5 bar or 1 to 1.3 bar in consideration of the condensation condition of (meth) acrylic acid and the moisture content condition depending on the saturated water vapor pressure, The internal temperature may be adjusted to 50 to 100 占 폚, or 50 to 80 占 폚.

On the other hand, through the absorption process, the (meth) acrylic acid aqueous solution is discharged to the lower part of the (meth) acrylic acid absorption tower 100, and the non-condensable gas deaerated by the (meth) acrylic acid is discharged to the upper part. In this case, the (meth) acrylic acid aqueous solution preferably contains (meth) acrylic acid in a concentration of 40% or more, or 40 to 90% by weight, or 50 to 90% It is advantageous.

The obtained (meth) acrylic acid aqueous solution can be supplied to the (meth) acrylic acid extraction tower 200 through the aqueous solution transfer line 102 as shown in FIG. 3, the (meth) acrylic acid aqueous solution may be divided into (meth) acrylic acid extraction tower 200 and distillation column 300 through aqueous solution transfer lines 102 and 103.

2, when the extraction step is introduced between the (meth) acrylic acid absorption step and the distillation step, most of the absorption solvent contained in the (meth) acrylic acid aqueous solution can be removed with a small energy in the extraction step, The processing load can be reduced. The extraction process will be described in detail with a separate table of contents.

On the other hand, when the extraction process is introduced between the (meth) acrylic acid absorption process and the distillation process and the aqueous (meth) acrylic acid solution is divided into the extraction process and the distillation process as shown in FIG. 3, The distillation process can be operated under more relaxed operating conditions and the overall energy efficiency can be improved. 3, the proportion of the (meth) acrylic acid aqueous solution to the (meth) acrylic acid extraction tower 200 and the distillation column 300 is divided into (meth) acrylic acid extraction tower 200 and distillation column 300, capacity, processing capability, energy efficiency increase effect of the entire process, and the like. According to one embodiment, 5 to 70 wt%, or 10 to 60 wt%, or 10 to 50 wt% of the (meth) acrylic acid aqueous solution is supplied to the (meth) acrylic acid extraction tower 200, It may be advantageous in terms of the expression of the above-mentioned effect to be supplied to the column 300.

On the other hand, at least a part of the non-condensable gas discharged to the upper part of the (meth) acrylic acid absorption tower 100 may be supplied to a process of recovering organic by-products (especially acetic acid) contained in the non-condensable gas, And can be discarded. That is, according to one embodiment, a process of contacting the non-condensable gas with an absorption solvent and recovering the acetic acid contained in the non-condensable gas may be performed.

The step of contacting the non-condensable gas with the absorbing 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 of 1 to 1.5 bar, preferably 1 to 1.3 bar, and an internal temperature of 50 to 100 ° C, preferably 50 to 80 ° C Respectively. 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 absorption solvent (process water) for absorbing acetic acid is supplied to the upper part of the acetic acid absorption tower 150, and an aqueous solution containing acetic acid is discharged to the lower part of the acetic acid absorption tower 150. The acetic acid-containing aqueous solution may be supplied to the upper part of the (meth) acrylic acid absorption tower 100 and used as an absorption solvent. In addition, the non-condensable gas in which the acetic acid is deaerated can be circulated and reused in the synthesis reaction process of (meth) acrylic acid.

II . Extraction process

(Meth) acrylic acid aqueous solution obtained through the above absorption process is contacted with an extraction solvent in an extraction column, and the (meth) acrylic acid aqueous solution is passed through an upper outlet of the extraction column, To obtain an acrylic acid extract, and to obtain an additional residue through the lower outlet of the extraction column.

According to one embodiment, in the extraction column 200, the (meth) acrylic acid aqueous solution is contacted with an extraction solvent to remove an extract having a substantial amount of (meth) acrylic acid dissolved therein and an additional residual amount of (meth) acrylic acid respectively. Here, the extracted liquid is obtained through the upper outlet of the extraction tower 200, and the additional liquid is obtained through the lower outlet of the extraction tower 200.

Thus, in the extraction column 200, most of the water contained in the aqueous solution can be removed through a method of contacting (meth) acrylic acid aqueous solution with an extraction solvent (that is, a method of using less energy than distillation). Accordingly, the burden on the distillation process in the distillation column 300 as a subsequent process can be reduced, and the energy efficiency of the entire process can be improved. Further, the polymerization reaction of (meth) acrylic acid which may occur in the distillation process can be minimized, and thus, improved operation stability can be secured.

On the other hand, as shown in FIG. 1, in the case of the continuous recovery method of the general (meth) acrylic acid including the absorption process of the (meth) acrylic acid, the extraction process and the distillation process, The residual balance of the organic phase and the aqueous phase are separated and phase separated. Since the amount of weight residue generated by the extraction and the amount of the residual balance discharged through the lower outlet of the extraction column are maintained substantially equal to each other, the amount of the remaining weight remaining in the lower portion of the extraction tower 200, This is maintained at a certain level. The water phase may be supplied to the absorber 100 through the additional balance transfer line 201 and used as the absorption water, assuming that the height of the interface is maintained at a constant level.

1, the interface between the organic phase and the water phase due to the residual balance at the bottom of the extraction column 200 can not be maintained at a constant height, and an excessive amount of the organic phase is supplied to the absorption tower 100 together with the water phase The absorption tower 100 is contaminated by the extraction solvent contained in the organic phase and the absorption efficiency is lowered. In addition, in a severe case, the extraction solvent flows into the (meth) acrylic acid synthesis reactor and causes serious safety problems. .

On the other hand, in the continuous recovery method of (meth) acrylic acid according to an embodiment of the present invention, as shown in FIG. 2, in the extraction step, the residual balance obtained through the lower outlet of the extraction tower 200, The organic phase is separated into an organic phase and an aqueous phase in a separate phase separation tank 350, and then the organic phase is supplied to the distillation process, and the water phase is fed to the absorption process. Accordingly, the continuous recovery method of (meth) acrylic acid according to one embodiment of the present invention can fundamentally block the introduction of an excessive amount of the organic phase into the absorption process, while maintaining the recovery efficiency of the (meth) acrylic acid. Also, in the continuous recovery method of (meth) acrylic acid according to an embodiment of the present invention, even if the interface management of the organic phase and the water phase fails at the residual balance portion under the extraction tower 200, It is possible.

According to an embodiment, the residual balance obtained through the lower outlet of the extraction tower 200 is supplied to the distillation column 300 through the additional balance transfer line 235 to the phase separation tank 350 of the distillation process to be described later, It is advantageous to improve the production efficiency according to the continuous process. In this case, it is premised that the same kind of solvent is used in the extraction step and the distillation step.

According to one embodiment, the organic phase obtained by phase separation of the residual balance can be supplied to the distillation process and used as an azeotropic solvent, and the water phase obtained by phase separation of the residual balance can be supplied to the absorption process and used as the absorption water have. Also, according to one embodiment, at least a portion of the organic phase by phase separation of the residue can be fed to the extraction process and used as an extraction solvent.

Meanwhile, scum may be included in the residual amount obtained through the lower outlet of the extraction tower 200. Accordingly, the continuous recovery method of (meth) acrylic acid according to an embodiment of the present invention is a method of recovering residual water discharged to the lower part of the extraction tower 200, as shown in FIGS. 4 and 5, And separating the filtrate obtained through the filtration into an organic phase and an aqueous phase.

According to one embodiment, the filtering of the residual balance obtained through the lower outlet of the extraction tower 200 can be performed using a filter to such an extent that the scum contained in the residual balance can be sufficiently removed, Or the configuration of the filter is not particularly limited. However, according to one embodiment, the filtering of the residual balance can be performed using a filter having pores with an average diameter of 50 mu m or less, or 0.1 to 30 mu m, or 0.5 to 20 mu m, or 0.5 to 10 mu m. That is, in order to sufficiently remove the scum, it is advantageous that the filter used for the filtering has pores having an average diameter of 50 μm or less. However, in consideration of the filtering efficiency and the process flow, it is advantageous that the filter has pores having an average diameter of 0.1 탆 or more.

In consideration of the possibility that an excessive amount of organic phase may be contained together with the water phase in the residual balance discharged to the lower part of the extraction tower 200, the filter used for the filtration may be an extraction solvent having resistance to (meth) acrylic acid Material. As a non-limiting example, the filter may be a metal, such as cotton, steel use stainless (SUS), or the like.

In addition, the filtering system 250 used for filtering the residual balance may include at least one filter satisfying the above condition, and two or more filters having pores having different average diameters may be connected in series .

The filtrate obtained through filtration of the residual balance may be supplied to the phase separation tank 350 of the distillation process described later through the filtrate transfer line 253 and subjected to phase separation treatment together with the upper effluent of the distillation column 300.

On the other hand, the extraction solvent supplied to the extraction tower 200 may preferably have solubility and hydrophobicity with (meth) acrylic acid. In view of the kind of the solvent required in the subsequent distillation step and the physical properties thereof, it is preferable that the extraction solvent has a boiling point lower than that of the (meth) acrylic acid. For example, the extraction solvent may be advantageous in process operation because it is a hydrophobic solvent having a boiling point of 120 ° C or less, or 10 to 120 ° C, or 50 to 120 ° C.

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. For on the day can.

According to one embodiment, the weight ratio of the extraction solvent to the (meth) acrylic acid aqueous solution supplied to the extraction tower 200 is 1: 1 to 1: 2, or 1: 1.0 to 1: 1.8, 1: 1.5, or 1: 1.1 to 1: 1.3. That is, in order to secure sufficient extraction efficiency, it is advantageous that the weight ratio of the extraction solvent to the (meth) acrylic acid aqueous solution supplied to the extraction tower 200 is maintained at 1: 1 or more. If the weight ratio is more than 1: 2, the extraction efficiency may be improved. However, the loss of (meth) acrylic acid may be increased in the subsequent distillation column 300, and the reflux of the solvent Which is undesirable.

According to one embodiment, the temperature of the (meth) acrylic acid aqueous solution in the extraction step is advantageously in the range of 10 to 70 ° C in terms of improvement in extraction efficiency.

As the extraction tower 200, a conventional extraction tower according to a liquid-liquid contact method can be used without any particular limitation. By way of non-limiting example, the extraction column 200 may be a Karr type reciprocating plate column, a rotary-disk contactor, a Scheibel column, a Kuhni column, a spray extraction column tower, a packed extraction tower, a pulsed packed column, and the like.

Through the extraction process, the extract liquid is discharged to the upper part of the extraction tower 200, and the extracted liquid is supplied to the distillation column 300 through the transfer line 203. In addition, an additional residual liquid is discharged to the lower portion of the extraction tower 200.

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 one embodiment, in a steady state where stable operation is performed, the extract contains 30-40 wt% of (meth) acrylic acid, 55-65 wt% of extraction solvent, 1-5 wt% of water, and residual organic byproducts . That is, most of the water (for example, 85 wt% or more) contained in the (meth) acrylic acid aqueous solution through the extraction step can be recovered as a residual liquid. As most of the water is recovered in the extraction tower 200, it is possible to reduce the distillation burden of the distillation column 300, thereby lowering the energy consumption and alleviating distillation conditions, thereby minimizing the polymerization reaction of (meth) acrylic acid It is possible to secure driving stability.

In addition, the residual balance obtained from the extraction tower 200 may contain some (meth) acrylic acid which has not been extracted. As a non-limiting example, the balance may contain (meth) acrylic acid in a concentration of 5 wt% or less, or 0.5 to 5 wt%, or 1 to 3 wt%. That is, according to the method of one embodiment, the concentration of (meth) acrylic acid contained in the residual liquid is as low as 5% by weight or less, and the loss of (meth) acrylic acid in the absorption column 100 and the extraction column 200 Can be minimized.

III . Distillation process

On the other hand, the continuous recovery method of (meth) acrylic acid according to an embodiment includes a distillation step of distilling a feed containing the (meth) acrylic acid extract to obtain (meth) acrylic acid.

According to one embodiment, the feed may be a (meth) acrylic acid extract. In this case, the feed may be fed to the distillation column 300 via the (meth) acrylic acid extract liquid transfer line 203, as shown in FIG.

Further, according to another embodiment, the feed may be a mixture of the (meth) acrylic acid aqueous solution and the (meth) acrylic acid extract. In this case, the feed may be fed to distillation column 300 via (meth) acrylic acid aqueous solution transfer line 103 and (meth) acrylic acid extract liquid transfer line 203, as shown in FIG.

The feed point to which the feed is fed is advantageously the middle portion of the distillation column 300 and is preferably 40 to 60% of the entire stage from the top of the distillation column 300, Or the like.

The feed supplied to the distillation column 300 is brought into contact with the azeotropic solvent introduced into the upper portion of the distillation column 300, and distillation is performed by evaporation and condensation while being heated to an appropriate temperature.

At this time, in order to efficiently separate the (meth) acrylic acid contained in the feed from the remaining components (for example, water, acetic acid, extraction solvent, etc.), the distillation is preferably performed in an azeotropic distillation method.

Here, the solvent to be applied to the azeotropic distillation method may be an azeotropic ratio with water and acetic acid, and may be a hydrophobic solvent which does not coexist with (meth) acrylic acid. The hydrophobic azeotropic solvent may have a boiling point lower than that of (meth) acrylic acid (for example, a boiling point of 120 ° C or less, or 10 to 120 ° C, or 50 to 120 ° C).

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. For at least one can be every day.

In particular, when the extraction process is introduced as shown in FIGS. 2 and 3, it is preferable that the hydrophobic azeotropic solvent is the same as the extraction solvent in the extraction process, considering the production efficiency and the like in the continuous process. When the same type of solvent is used in the extraction process and the distillation process, at least a part of the solvent distilled in the distillation column 300 and recovered through the phase separation tank 350 is supplied to the (meth) acrylic acid extraction tower 200 And can be reused as an extraction solvent.

Through such a distillation process, the components other than (meth) acrylic acid in the feed are discharged to the upper portion of the distillation column 300 together with the azeotropic solvent, and the (meth) acrylic acid is recovered to the lower portion of the distillation column 300.

At this time, the upper effluent of the distillation column 300 may be supplied to the phase separation tank 350 and reused after a predetermined treatment. A relatively light liquid (for example, an organic phase) is supplied to the upper portion of the phase separating tank 350, and a relatively heavy liquid (for example, an organic phase) (For example, a water phase) may be recovered to the lower portion of the phase separation tank 350.

As an example, the upper effluent of the distillation column 300 may be separated into an organic phase containing an azeotropic solvent and an aqueous phase containing water in the phase separation tank 350. 2 or 3, the residual balance of the extraction process is supplied to the phase separation tank 350 through the additional balance transfer line 235 and subjected to phase separation with the upper effluent of the distillation column 300 . 4 or 5, when the filtration system 250 is introduced into the extraction process, the filtrate obtained through filtration of the residual balance is transferred to the phase separation tank 350 through the filtrate transfer line 253 And may be subjected to phase separation treatment together with the upper discharge liquid of the distillation column 300.

Here, the separated organic phase may be supplied to the upper end of the distillation column 300 and used as an azeotropic solvent. If necessary, at least a part of the organic phase may be supplied to the (meth) acrylic acid extraction tower 200 and used as an extraction solvent. At least a part of the water phase separated in the phase separation tank 350 may be supplied to the (meth) acrylic acid absorption tower 100 and used as the absorption water, and a part thereof may be treated as wastewater.

The acetic acid may be partially contained in the aqueous phase, and the concentration of the acetic acid contained in the aqueous phase may vary depending on the kind of the azeotropic solvent and the reflux ratio. As a non-limiting example, the concentration of acetic acid contained in the aqueous phase may be 1 to 50 wt%, preferably 2 to 40 wt%, more preferably 3 to 30 wt%.

The (meth) acrylic acid aqueous solution is passed through the (meth) acrylic acid absorption tower 100, the (meth) acrylic acid extraction tower 200, the distillation column 300, May be polymerized to form a polymer such as dimer or oligomer. In order to minimize the polymerization of such (meth) acrylic acid, a conventional polymerization inhibitor may be added to the distillation column 300.

On the other hand, the lower effluent of the 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 and the like. Accordingly, if necessary, a step of supplying the lower discharge liquid of the 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 discharge liquid. The crude (meth) acrylic acid (CAA) recovered 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 the method for recovering (meth) acrylic acid according to this embodiment, each of the above-described steps can be carried out organically and continuously. In addition to the steps described above, processes that can be performed conventionally before or after each step may be further included and performed.

( Mat ) Continuous recovery of acrylic acid

Meanwhile, according to another embodiment of the present invention, as shown in FIG. 2,

(Meth) acrylic acid absorption tower (100) for obtaining a (meth) acrylic acid aqueous solution by contacting water with a mixed gas containing (meth) acrylic acid, an organic by-product, and water vapor produced by a synthesis reaction of (meth) acrylic acid;

(Meth) acrylic acid aqueous solution obtained from the absorption tower 100 is contacted with the extraction solvent by contacting the absorption tower 100 with the (meth) acrylic acid aqueous solution transfer line 102, A (meth) acrylic acid extraction tower 200 to obtain an extract and an additional residue;

(Meth) acrylic acid extract solution obtained from the extraction column 200 is distilled to obtain (meth) acrylic acid by a distillation column (distillation column) 200 connected to the extraction column 200 by a (meth) acrylic acid extract liquid transfer line 203, 300); And

A phase separation tank 350 connected to the extraction tower 200 by an additional balance transfer line 235 for separating the residual balance obtained from the extraction tower 200 into an organic phase and an aqueous phase,

(Meth) acrylic acid.

According to another embodiment of the present invention, as shown in Fig. 3,

(Meth) acrylic acid absorption tower (100) for obtaining a (meth) acrylic acid aqueous solution by contacting water with a mixed gas containing (meth) acrylic acid, an organic by-product, and water vapor produced by a synthesis reaction of (meth) acrylic acid;

(Meth) acrylic acid aqueous solution obtained from the absorption tower 100 is contacted with the extraction solvent by contacting the absorption tower 100 with the (meth) acrylic acid aqueous solution transfer line 102, A (meth) acrylic acid extraction tower 200 to obtain an extract and an additional residue;

(Meth) acrylic acid aqueous solution conveying line 103 connected to the absorption tower 100 by the (meth) acrylic acid extract liquid conveying line 203, and the absorption tower (200) (Meth) acrylic acid obtained by distilling a mixture containing at least a part of the (meth) acrylic acid aqueous solution obtained from the distillation column 200 and the (meth) acrylic acid extract obtained from the extraction column 200 to obtain (meth) acrylic acid,

A phase separation tank 350 connected to the extraction tower 200 by an additional balance transfer line 235 for separating the residual balance obtained from the extraction tower 200 into an organic phase and an aqueous phase,

(Meth) acrylic acid.

The continuous recovery device of (meth) acrylic acid according to the above embodiments can be operated according to the above-mentioned continuous recovery method of (meth) acrylic acid.

As shown in FIGS. 4 and 5, in the apparatuses of the embodiments shown in FIGS. 1 and 2, the weight balance obtained from the extraction tower 200 is filtered to remove the scum contained in the weight balance , And a filtration system (250) for supplying the filtrate to the phase separation tank (350) through a filtrate transfer line (253).

The filtration system 250 may have an average diameter of 50 mu m or less, or 0.1 to 30 mu m, or 0.5 to 20 mu m, or 0.5 mu m or 0.5 mu m, in order to sufficiently remove the scum obtained through the lower outlet of the extraction tower 200. [ It is preferable that a filter having pores of 10 mu m to 10 mu m is provided. The filter provided in the filtering system 250 is preferably an extraction solvent and a material having resistance to (meth) acrylic acid. Non-limiting examples of the filter include a metal such as cotton, SUS (steel use stainless) It may be a material.

On the other hand, the (meth) acrylic acid absorption tower 100 may be a packed tower or a multistage tray tower for improving the contact efficiency between the (meth) acrylic acid-containing mixed gas 1 and water as an absorption solvent . Here, the filling column may have a filler such as a rashing ring, a pall ring, a saddle, a gauze, and a structured packing.

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

In addition, the acetic acid absorption tower 150, the (meth) acrylic acid aqueous solution transfer line 102, the extract liquid transfer line 203, the phase separation tank 350, the high boiling point byproduct separation tower 400, And may have a conventional configuration in the field.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention without limiting it thereto.

Comparative Example

Acrylic acid extraction column was 50 stages in total, about 3 m in total height, and acrylic acid aqueous solution (acrylic acid concentration about 65.5 wt%, acetic acid concentration about 2.25 wt%) was introduced at the uppermost stage and toluene was supplied to the extraction solvent inlet. At this time, the weight ratio of the acrylic acid aqueous solution and toluene supplied to the extraction column was fixed to be about 1: 1.3. The amount of the acrylic acid aqueous solution was adjusted to 91.3 g / min and the toluene amount was adjusted to 115.8 g / min.

Then, the flow rate of the residual solution was adjusted so that the interface between the organic phase and the water phase formed by the residual solution remaining at the lower part of the extraction column could be maintained at a constant level. At the beginning of the experiment, the flow rate of the residual solution was maintained at about 25.0 g / min, so that the interface remained at a constant level, but the water-soluble solid slurry (scum) accumulated at the interface during the long operation. As a result, the interfacial management failed and the residual amount was increased by about 20% to about 30.6 g / min. At this time, the concentration of acrylic acid in the residual liquid mixed with the organic phase and the water phase in emulsion form was about 1.17 wt%, and the toluene concentration was about 13.6 wt%. These residual amounts were not suitable for use as an absorbing water of the acrylic acid absorption process due to the high toluene concentration.

Example

The residual liquid having a concentration of acrylic acid of about 1.17% by weight and a toluene concentration of about 13.6% by weight obtained in the process of the comparative example was supplied to the downstream phase separation tank and separated into an organic phase and an aqueous phase together with a distillation column. At this time, about 0.72 wt% of acrylic acid and about 730 ppm of toluene were contained in the water phase obtained in the phase separation tank. That is, the aqueous phase obtained in the above-mentioned phase separation tank was found to have mostly removed toluene and recovered some acrylic acid as compared with the residual liquid obtained in the extraction column of the comparative example, and was sufficient for use as the absorption water of the acrylic acid absorption process .

1: (meth) acrylic acid-containing mixed gas 100: (meth) acrylic acid absorption tower
102: (meth) acrylic acid aqueous solution transfer line 150: Acetic acid absorption tower
200: (meth) acrylic acid extraction column 201: additional balance transfer line
203: Extract liquid transfer line 235: Additional liquid transfer line
250: Filtration system 253: Filtrate transfer line
300: distillation column 350: phase separation column
400: High boiling point byproduct separation tower CAA: crude (meth) acrylic acid
HPAA: High purity (meth) acrylic acid

Claims (7)

An absorption step of obtaining a (meth) acrylic acid aqueous solution by bringing a mixed gas containing (meth) acrylic acid, organic by-products and water vapor produced by the synthesis reaction of (meth) acrylic acid into contact with water;
(Meth) acrylic acid aqueous solution obtained through the absorption process is contacted with an extraction solvent in an extraction column to obtain an (meth) acrylic acid extract solution through an upper outlet of the extraction column, and the An extraction step of obtaining an additional balance; And
(Meth) acrylic acid by distilling a feed comprising at least a part of the (meth) acrylic acid aqueous solution obtained through the absorption process and the (meth) acrylic acid extract obtained through the extraction step ;
Separating the residual balance obtained through the lower outlet of the extraction column into an organic phase and an aqueous phase in a phase separation tank in the extraction step, feeding the organic phase to the distillation step, and supplying the aqueous phase to the absorption step Meth) acrylic acid.
The method according to claim 1,
Wherein at least a portion of the organic phase by phase separation of the residual liquid is fed to the extraction step.
The method according to claim 1,
Removing the scum contained in the residual balance by filtering the residual residue obtained through the extraction process,
Wherein the filtrate obtained through the filtration is subjected to phase separation with an organic phase and an aqueous phase, thereby continuously recovering the (meth) acrylic acid.
delete delete (Meth) acrylic acid absorption tower (100) for obtaining a (meth) acrylic acid aqueous solution by contacting water with a mixed gas containing (meth) acrylic acid, an organic by-product, and water vapor produced by a synthesis reaction of (meth) acrylic acid;
(Meth) acrylic acid aqueous solution obtained from the absorption tower 100 is contacted with the extraction solvent by contacting the absorption tower 100 with the (meth) acrylic acid aqueous solution transfer line 102, A (meth) acrylic acid extraction tower 200 to obtain an extract and an additional residue;
(Meth) acrylic acid aqueous solution conveying line 103 connected to the absorption tower 100 by the (meth) acrylic acid extract liquid conveying line 203, and the absorption tower (200) (Meth) acrylic acid obtained by distilling a mixture containing at least a part of the (meth) acrylic acid aqueous solution obtained from the distillation column 200 and the (meth) acrylic acid extract obtained from the extraction column 200 to obtain (meth) acrylic acid,
A phase separation tank 350 connected to the extraction tower 200 by an additional balance transfer line 235 for separating the residual balance obtained from the extraction tower 200 into an organic phase and an aqueous phase,
(Meth) acrylic acid.
The method according to claim 6,
The filtered residual liquid obtained from the extraction tower 200 is filtered to remove the scum contained in the residual liquid and the filtrate is supplied to the phase separation tank 350 through the filtrate transfer line 253. [ The system 250,
(Meth) acrylic acid.

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