WO2016076559A1

WO2016076559A1 - Continuous recovery method and apparatus of (meth)acrylic acid

Info

Publication number: WO2016076559A1
Application number: PCT/KR2015/011597
Authority: WO
Inventors: 민윤재; 백세원; 송종훈; 유설희
Original assignee: 주식회사 엘지화학
Priority date: 2014-11-14
Filing date: 2015-10-30
Publication date: 2016-05-19
Also published as: KR20160057928A

Abstract

The present invention relates to a continuous recovery method of (meth)acrylic acid and an apparatus used in the recovery method. According to the present invention, provided are a continuous recovery method of (meth)acrylic acid which enables a more stable process operation and energy saving, and particularly enables reduction of the load on an extraction process for the aqueous (meth)acrylic acid solution, and at the same time, enables an increase in feed throughput in the extraction process and a reduction in extraction solution usage; and an apparatus which can be used suitably in the method.

Description

【Specification】

[Name of invention]

Continuous recovery method and apparatus of (meth) acrylic acid

[Cross Citation with Related Application (s)]

This application claims the benefit of priority based on Korean Patent Application No. 10-2014-0159168 of January 14, 2014, and all contents disclosed in the literature of that Korean patent application are incorporated as part of this specification.

Technical Field

The present invention relates to a method and apparatus for continuous recovery of (meth) acrylic acid. [Background]-

(Meth) acrylic acid is generally produced by a method of reacting gas phase oxidation in the presence of a catalyst with a compound such as propane, propylene, (meth) acrelane and the like. For example, in the presence of a suitable catalyst in the reactor, propane, propylene and the like are converted to (meth) acrylic acid via (meth) acrolein by gas phase oxidation reaction, and (meth) acrylic acid, Mibanung propane or propylene, ( A reaction product mixed gas is obtained that includes meth) arklane, an inert gas, carbon dioxide, water vapor, and various organic by-products such as acetic acid, low-boiling by-product, high-boiling by-product, and the like. The said (meth) acrylic acid containing mixed gas is contacted with absorption solvents, such as process water, in a (meth) acrylic acid absorption tower, and is collect | recovered by the (meth) acrylic-acid aqueous solution. In general, the (meth) acrylic acid aqueous solution is distilled and purified to obtain (meth) acrylic acid. In order to improve the recovery efficiency of such (meth) acrylic acid, various methods for controlling the process conditions or the process order have been proposed. Among them, a method of azeotropic distillation using a hydrophobic solvent in a distillation column is known as a method for separating water and acetic acid from an aqueous (meth) acrylic acid solution obtained in a (meth) acrylic acid absorption tower. Alternatively, a method of supplying an aqueous (meth) acrylic acid solution to an extraction column to obtain a (meth) acrylic acid extract with reduced water content and a balance thereof and distilling the extract to obtain (meth) acrylic acid is known.

However, according to this known process, in the extraction process and the distillation process Not only is the loss rate of (meth) acrylic acid high but also the processing burden of the extraction process is high, causing flooding or unstable temperature profile inside the distillation column.

[Content of invention]

[Problem to solve]

The present invention is to provide a continuous recovery method of (meth) acrylic acid to increase the efficiency of the extraction process with respect to the aqueous (meth) acrylic acid solution to enable a stable operation and energy saving.

Moreover, this invention is providing the apparatus which can be used for the continuous rare water method of the said (meth) acrylic acid.

[Measures of problem]

According to the invention,

An absorption process of bringing a mixed gas containing (meth) acrylic acid, organic by-products and water vapor generated by the synthesis reaction of (meth) acrylic acid into water in a (meth) acrylic acid absorption tower to obtain an aqueous (meth) acrylic acid solution;

A phase separation step of phase-separating the (meth) acrylic acid aqueous solution obtained through the absorption process and the (meth) acrylic acid extract obtained through the extraction process to be described later in a decanter to obtain an organic phase and an aqueous phase;

An extraction step of contacting the aqueous phase obtained through the phase separation process with an extraction solvent in an extraction column to obtain a (meth) acrylic acid extract and an extract; And

Distillation process of distilling a feed containing the organic phase obtained through the phase separation process to obtain (meth) acrylic acid

Provided is a continuous recovery method of (meth) acrylic acid comprising a.

In addition, according to the present invention,

A mixed gas inlet supplied with a mixed gas containing (meth) acrylic acid, organic by-products and water vapor generated by the synthesis reaction of (meth) acrylic acid, and an aqueous (meth) acrylic acid solution obtained by contacting the mixed gas with water is discharged. (Meth) acrylic acid absorption tower 100 is provided with an aqueous solution outlet;

(Meth) acrylic acid aqueous solution inlet connected to the aqueous solution outlet of the absorption tower 100 and the aqueous solution transfer line (1 15), the extract of the extraction column 200 to be described later The (meth) acrylic acid extract inlet connected through the outlet and the extract liquid conveying line 215, the organic phase outlet through which the introduced (meth) acrylic acid aqueous solution and the extract phase are discharged, and the aqueous phase obtained by the phase separation A decanter 150 having a water discharge port discharged therefrom;

The water inlet of the decanter 150 and the water inlet connected through the water transfer line 152, the extraction liquid outlet through which the (meth) acrylic acid extract obtained by contacting the introduced water and the extraction solvent is discharged, and the balance thereof is discharged. A (meth) acrylic acid extraction column (200) equipped with a drainage liquid outlet; And

A distillation column with an (meth) acrylic acid outlet through which an organic phase inlet of the decanter 150 and an organic phase inlet connected through an organic phase transfer line 153 and a (meth) acrylic acid obtained by distillation of a feed including the introduced organic phase are discharged. (300)

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

Prior to this, the terminology used herein is for reference only to specific embodiments and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” include plural forms as well, unless the phrases clearly indicate the opposite. In addition, the meaning of "included" as used in the specification specifies a specific characteristic, region, integer, step, operation, element or component, excluding the addition of other specific characteristic, region, integer, step, operation, element, or component. It is not meant to be.

And, unless explicitly stated throughout the present specification, some terms are defined as follows.

'(Meth) acrylic acid' may be used to mean acrylic acid, methacrylic acid, or a combination thereof.

The term "(meth) acrylic acid-containing mixed gas" refers to a mixed gas that can be produced when synthesizing (meth) acrylic acid by vapor phase oxidation reaction. Non-limiting examples include propane, propylene, butane, isobutylene, and

The (meth) acrylic acid-containing mixed gas can be obtained by a gas phase oxidation reaction of at least one compound ('raw compound') selected from the group consisting of (meth) arklane in the presence of a catalyst. In this case, the (meth) acrylic acid-containing mixed gas includes (meth) acrylic acid, a raw material compound, a (meth) acrylic acid inert gas, carbon monoxide, carbon dioxide, water vapor, and various organic by-products (acetic acid, low boiling point by-products (light ends)). High boiling by-products, etc.). Herein, the term 'low ends' or 'heavies' is a kind of by-product that can be produced in the process of preparing and recovering the desired (meth) acrylic acid, and the molecular weight is higher than that of (meth) acrylic acid. Collectively, small or large compounds. And, the poorly water-soluble suspended solids formed by the organic by-products

It is called 'scum'.

'(Meth) acrylic acid aqueous solution' is an aqueous solution containing (meth) acrylic acid, and may be obtained by, for example, contacting the (meth) acrylic acid-containing mixed gas with an absorption solvent including water.

The term "feed" in the extraction process refers to a liquid mixture containing the solute to be extracted, and a solute that is soluble in the extraction solvent ^ and other components that are not soluble. may be a mixture of inert materials. Here, when the extraction solvent is added to the feed, the solute is dissolved from the feed into the extraction solvent by mass transfer. As a result, the extraction solvent in which the solute is dissolved to form an extract solution, and the feed having lost a considerable amount of solute to form a traffic solution.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. However, the present invention may 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 well-known (meth) acrylic acid recovery method including the absorption process, extraction process, distillation process, etc. with respect to a (meth) acrylic acid containing mixed gas, Increasing the throughput of the extraction process to increase the recovery of (meth) acrylic acid increases the probability of occurrence of fulling on the top of the extraction column. To prevent this, a method of increasing the capacity of the extraction column or changing the internal stirring means of the extraction column (for example, plate free area of the Reciprocating plate column or the blade of the Scheibel column) may be applied. However, in order to increase the capacity of the extraction column or to change the stirring means, such a huge cost is required. Accordingly, the present inventors have conducted a study on a method of improving the treatment efficiency of an extraction process without changing the existing extraction column design in a method of recovering (meth) acrylic acid including an absorption process, an extraction process, and a distillation process. It was.

As a part thereof, according to the present invention, the aqueous (meth) acrylic acid solution obtained in the absorption step and the (meth) acrylic acid extract obtained in the extraction step are left in a decanter to obtain an aqueous phase and an organic phase by phase separation. A method of feeding an aqueous phase to an extraction process and feeding the organic phase to a distillation process is provided. This method can lower the concentration of (meth) acrylic acid by phase separation in a decanter before feeding the aqueous (meth) acrylic acid solution to the extraction process, thereby reducing the load on the extraction process. That is, unlike the general recovery method in which the (meth) acrylic acid aqueous solution obtained in the absorption step is supplied to the extraction step and the extract is supplied to the distillation step, the recovery method of (meth) acrylic acid provided through the present invention is (meth) The stream mixed with the aqueous acrylic acid solution and its extract is left in a decanter to induce phase separation, and then the aqueous phase recovered therefrom is fed to the extraction process and the remaining organic phase is fed to the distillation process. As a result, in the extraction process, it is possible to suppress the flooding phenomenon under more vigorous stirring conditions during the liquid-liquid extraction, and to process a larger amount of feed per unit time than the extraction column of a similar scale. In addition, this method enables the extraction efficiency to be stably maintained even when the solvent / feed ratio is reduced during the operation of the extraction process, thereby reducing the amount of extraction solvent used. And this method enables energy savings in the distillation process following the extraction process. I. (Method of acrylic acid recovery) According to one embodiment of this invention,

(Meth) was produced by the synthesis banung of acrylic acid (meth) acrylic acid, heunhap gas containing the organic by-products and water vapor (meth) acrylic acid in the absorber in contact with water ^"(meth) acrylic acid aqueous solution to obtain the absorption process;

■ A phase separation process of separating the (meth) acrylic acid aqueous solution obtained through the absorption process and the (meth) acrylic acid extract obtained through the extraction process described later in a decanter to obtain an organic phase and an aqueous phase;

Provided is a continuous recovery method of (meth) acrylic acid comprising a.

In addition, according to one embodiment of the invention,

An absorption step of obtaining a (meth) acrylic acid aqueous solution by contacting a mixed gas containing (meth) acrylic acid, organic by-products and water vapor produced by the synthesis reaction of (meth) acrylic acid with water in a (meth) acrylic acid absorption tower;

A phase separation process in which a part of the aqueous (meth) acrylic acid solution obtained through the absorption process and the (meth) acrylic acid extract obtained through the extraction process are separated in a decanter to obtain an organic phase and an aqueous phase;

Distillation process of distilling a feed including the remainder of the aqueous solution of (meth) acrylic acid obtained through the absorption process and the organic phase obtained through the phase separation process to obtain (meth) acrylic acid

Provided is a continuous recovery method of (meth) acrylic acid comprising a.

Hereinafter, referring to FIGS. 1 and 2, each process that may be included in an embodiment of the present invention will be described in detail.

(Absorption process)

The absorption step is a step for obtaining an aqueous (meth) acrylic acid solution. The (meth) acrylic acid-containing mixed gas obtained through the synthesis reaction of (meth) acrylic acid can be carried out by contacting with an absorption solvent including water.

As a non-limiting example, the synthesis of (meth) acrylic acid may be carried out by oxidizing at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, and (meth) acrolein under a gas phase catalyst. Can be. In this case, the gas phase oxidation reaction may proceed under a gas phase oxidation reaction and reaction conditions of a conventional structure. Conventional catalysts in the gas phase oxidation reaction may also be used, for example, the catalysts disclosed in Korean Patent Nos. 0349602 and 037818 may be used. The (meth) acrylic acid-containing mixed gas produced by the gas phase oxidation reaction includes, in addition to (meth) acrylic acid as a target product, unreacted raw compound, intermediate (meth) acrolein, inert gas, carbon dioxide, water vapor, and various organic by-products (acetic acid). , Low boiling by-products, high boiling by-products, etc.) may be included.

And, referring to Figure 1,. The (meth) acrylic acid aqueous solution can be obtained by supplying a (meth) acrylic acid-containing mixed gas (1) to the (meth) acrylic acid absorption tower 100 and contacting with an absorption solvent containing water.

Here, the type of the (meth) acrylic acid absorption tower 100 may be determined in consideration of the contact efficiency of the mixed gas 1 and the absorption solvent. As a non-limiting example,

The (meth) acrylic acid absorption tower 100 may be an absorption tower of a packed column type or an absorption tower of a multistage tray type. The packed column type absorption tower may include a layering agent such as a rashing ring, a pall ring, a saddle, a gauze, and a structured packing.

In addition, in consideration of the efficiency of the absorption process, the mixed gas 1 may be supplied to the lower portion of the absorption tower 100, and the absorption solvent including water may be supplied to the upper portion of the absorption tower 100.

The absorption solvent may include water such as scum water, deionized water and the like, and may include circulating process water introduced from another process (eg, an aqueous phase recycled from an extraction process and / or a distillation process). In addition, the absorption solvent may contain a small amount of organic by-products introduced from other processes (for example Acetic acid). However, in consideration of the absorption efficiency of (meth) acrylic acid, the absorption solvent (particularly the circulation process water) supplied to the absorption tower 100 is preferably such that the organic by-products are included in an amount of 15% by weight or less.

In addition, the (meth) acrylic acid absorption tower 100 may have an internal pressure of 1 to 1.5 bar or 1.3 to 1.3 bar in consideration of condensation conditions of the (meth) acrylic acid and water content according to the saturated water vapor pressure. It can be operated under an internal temperature of 100 ^° C or 50 to 80 ^° C.

On the other hand, in the absorption step, the (meth) acrylic acid aqueous solution is discharged to the lower portion of the (meth) acrylic acid absorption tower 100, the non-condensable gas from which (meth) acrylic acid is degassed is discharged. In this case, the (meth) to that aqueous acrylic acid solution contains a concentration of 40 wt. ⁰ /. Or more, or 40 to 90 weight ^_0/0, or 50 to 90 weight ⁰ /. Of (meth) acrylic acid in the efficiency aspects of the overall process May be advantageous.

The obtained (meth) acrylic acid aqueous solution is supplied to the decanter 150 via the aqueous solution transfer line 1 15, as shown in FIG. 1. Alternatively, the obtained ^' (meth) acrylic acid aqueous solution may be supplied to the decanter 150 and the distillation column 300 through the aqueous solution transfer lines 1 15 and 130 as shown in FIG. 2. That is, according to the embodiment of the invention shown in Figures 1 and 2, the (meth) acrylic acid aqueous solution obtained in the (meth) acrylic acid absorption tower 100 is not directly supplied to the extraction column 200, decanter 150 Via the (meth) acrylic acid concentration is supplied to the extraction column 200 in a low state. In addition, the (meth) acrylic acid extract obtained in the extraction column 200 is not directly supplied to the distillation column 300, but is supplied to the distillation column 300 as a phase separated organic phase via the decanter 150. Here, the flow in the decanter 150 and the extraction column 200 will be described separately.

In the embodiment as shown in FIG. 2, the ratio of dividing the (meth) acrylic acid aqueous solution to the decanter 150 and the distillation column 300 may be based on a comprehensive consideration of the capacity, treatment performance, and energy efficiency of each column. Can be determined. According to an embodiment of the invention, 5 to 70 weight ⁰ /., Or 10 to 60 weight ⁰ /., Or 10 to 50 weight ⁰ /. Of the (meth) acrylic acid aqueous solution is used as the decanter 150. Feeding the remainder to the distillation column 300 may be advantageous in minimizing the loss of (meth) acrylic acid and reducing overall energy consumption. Meanwhile, at least some of the non-uniform gas discharged to the upper portion of the (meth) acrylic acid absorption tower 100 may be supplied to a process of recovering organic by-products (particularly acetic acid) included in the non-condensable gas, and the rest of the waste gas incinerator. Can be disposed of and discarded. That is, according to the exemplary embodiment of the present invention, the non-condensable gas may be contacted with an absorption solvent to recover the acetic acid contained in the non-condensable gas. The process of contacting the non-uniform gas with the absorption solvent may be performed in the acetic acid absorption tower 50. As a non-limiting example, an absorption solvent (process water) for absorbing acetic acid may be supplied to the upper portion of the acetic acid absorption tower 50, and an aqueous solution containing acetic acid may be discharged to the lower portion of the acetic acid absorption tower 50. . In addition, the acetic acid-containing aqueous solution may be supplied to the upper portion of the (meth) acrylic acid absorption tower 100 to be used as an absorption solvent. In addition, the non-condensable gas from which acetic acid is degassed may be circulated to the synthesis reaction process of (meth) acrylic acid and reused. At this time, for the effective absorption of acetic acid, the acetic acid absorption tower 50 is operated under an internal pressure of 1 to 1.5 bar or 1 to 1.3 bar, and an internal temperature of 50 to 100 ^° C or 50 to 80 ^° C. Can be. In addition to the specific operating conditions of the acetic acid absorption tower (50). It may be according to the contents disclosed in Republic of Korea Patent Publication No. 2009-0041355.

(Phase Separation Process)

On the other hand, the (meth) acrylic acid aqueous solution obtained through the absorption process and the (meth) acrylic acid extract obtained through the extraction process to be described later in the decanter 150 is subjected to a phase separation process of obtaining an organic phase and an aqueous phase.

Referring to FIG. 1, the decanter 150 is supplied with an aqueous (meth) acrylic acid solution from the absorption tower 100 through an aqueous solution transfer line 1 15, and at the same time, an extract liquid transfer line 215 from the extraction column 200. The (meth) acrylic acid extract is supplied via. Here, the decanter 150 is a device for separating liquid phases that are not mixed with each other by gravity or centrifugal force, and the like, and a relatively light phase (for example, an organic phase) At the top of the decanter 350, a relatively heavy phase (eg water phase) is withdrawn to the bottom of the decanter 350. Here, the organic phase includes the extraction solvent used in the extraction process and (meth) acrylic acid dissolved therein, and the water phase includes the absorption solvent used in the absorption process and (meth) acrylic acid dissolved therein. And, the organic phase, which is a relatively light phase, is obtained through the upper outlet of the decanter 150, and the aqueous phase, which is a relatively heavy phase, is obtained through the lower outlet of the decanter 150. The organic phase is supplied to the distillation column 300 through the organic phase transfer line 153 to separate the solvent, and the aqueous phase is supplied to the extraction column 200 through the aqueous phase transfer line 152 to provide water (absorbent solvent). Separation takes place.

At this time, the aqueous phase supplied to the extraction column 200 has a (meth) acrylic acid concentration of significantly lower than the (meth) acrylic acid aqueous solution obtained through the absorption process. That is, at least 40%, preferably 40 to 95%, or 40 to 90%, or 50 to 40% of the (meth) acrylic acid aqueous solution supplied to the decanter 150 and the (meth) acrylic acid contained in the (meth) acrylic acid extract are 90%, or 60 to 85 ⁰ /. Of (meth) acrylic acid can be recovered through the organic phase. Thus, the water phase obtained through phase separation in the decanter 150 may exhibit a lower level of (meth) acrylic acid.

As a non-limiting example, when the absorption process yields an aqueous (meth) acrylic acid solution having a concentration of (meth) acrylic acid at a concentration of about 65% by weight ⁰ /., At least 40 ⁰ / of the (meth) acrylic acid contained in the (meth) acrylic acid aqueous solution Can be recovered to the organic phase through phase separation in the decanter 150. And, water is obtained through the phase separation in the decanter 150 may indicate a much lower (meth) acrylic acid concentration (e.g., (meth) acrylic acid concentration of about ₃₉ weight ⁰ /. Or less). As such, the high concentration of the (meth) acrylic acid ^' aqueous solution and the extract are phase separated in the decanter 150, through which the water phase having a lower concentration of (meth) acrylic acid is applied to the extraction column 200, thereby effectively reducing the load of the extraction process. Can be. Furthermore, the load of the distillation process can be reduced by supplying the organic phase containing the high concentration of (meth) acrylic acid obtained through the phase separation to the distillation column 300. Extraction process

On the other hand, the extraction process of obtaining the (meth) acrylic acid extract and its balance by contacting the aqueous phase obtained through the phase separation process with the extraction solvent in the extraction column.

According to an embodiment of the present invention, unlike the general recovery method of supplying the aqueous (meth) acrylic acid solution obtained in the absorption process to the extraction process and the extract to the distillation process, the stream in which the aqueous (meth) acrylic acid solution and the extract solution are mixed After standing in the decanter 150 to induce phase separation, the aqueous phase recovered therefrom is supplied to the extraction process, and the remaining organic phase is supplied to the distillation process. As a result, the water phase having lowered the (meth) acrylic acid concentration is supplied to the extraction process, thereby effectively reducing the load of the extraction process. That is, in the extraction process, it is possible to suppress the flooding phenomenon under more vigorous stirring conditions during liquid-liquid extraction, and increase the feed throughput that can be processed under a similarly scaled extraction column. Furthermore, this method enables the extraction efficiency to be stably maintained even though the solvent / feed ratio is reduced during the operation of the extraction process, thereby reducing the amount of extraction solvent used. This effect also enables energy savings in the distillation process following the extraction process.

According to an embodiment of the invention, the aqueous phase supplied from the decanter 150 to the extraction column 200 via the aqueous phase transfer line 152 is in contact with an extraction solvent, whereby an extract liquid in which a significant amount of (meth) acrylic acid is dissolved in the extraction solvent. It is discharged as a traffic solution which has lost a significant amount of extract solution and (meth) acrylic acid, respectively. At this time, the relatively light phase of the extract is obtained through the upper outlet of the extraction column 200, the relatively heavy phase of the extract is obtained through the lower outlet of the extraction column. Before the extraction liquid is discharged from the extraction column 200, a certain amount is left in a fixed state in the lower stationary section of the extraction column, some of which is discharged to the lower outlet of the extraction column.

In the extraction process, the balance is supplied to the decanter 350 through the balance transfer line 235, and the aqueous phase together with the upper discharge of the distillation column 300. Phase separation into the organic phase. By the way, since the scum may contain scum, the scum is filtered to remove scum _; After that, supplying the filtrate to the decanter 350 may be preferable in terms of securing operational stability. Also optionally, the balance may be circulated in the absorption process and used as an absorption solvent of (meth) acrylic acid.

Meanwhile, the extraction solvent supplied to the extraction column 200 may have solubility and hydrophobicity for (meth) acrylic acid. However, in view of the physical properties of the azeotropic solvent required in the subsequent distillation column 300, the extraction solvent preferably has a lower boiling point than (meth) acrylic acid. For example, the extraction solvent may be daily for a hydrophobic having a boiling point of 120 ^° C or less, or from 10 to 120 ^° C, or from 50 to 120 ^° C.

Specifically, the extraction solvent is benzene, toluene, xylene, n-heptane, n-heptane, cycloheptane, cycloheptene, 1-heptene (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, 2-methyl-1 -heptene, 6-methyl -1 -heptene (6-methyl-1 -heptene), 4-methyl-1 -heptene (4-methyl-1 -heptene), 2-ethyl-1 -nuxene (2-ethyl-1 -hexene), ethylcyclo Pentane (ethylcydopentane), 2-methyl-1 -nuxene (2-methyl-1 -hexene), 2,3-dimethylpentane (2,3-dimethylpentane), 5-methyl-1 -nuxene (5-methyl-1- hexene), and isopropyl-butyl-ether It may be one or more solvents selected from the group consisting of.

In addition, the supply amount of the extraction solvent, the solvent / feed ratio (solvent / feed ratio) to the water phase supplied to the extraction column 200 is 0.8: 1 to 0.8: 2, or 0.8: 1 to 0.8: 1 .8, Or 0.8: 1 to 0.8: 1 .5, or 0.8: 1 to 0.8: 1 .3. That is, since the aqueous phase contains relatively low concentration of (meth) acrylic acid, the extraction load can be lowered, and the extraction efficiency is reduced even when the solvent / feed ratio is reduced during the operation of the extraction process. It can be kept stable. In particular, since the concentration of (meth) acrylic acid is lowered by phase separation in a decanter before supplying the aqueous (meth) acrylic acid solution to the extraction process, the load of the extraction process can be reduced. For reference, in an extraction process without a decanter, a weight ratio (weight ratio of extraction solvent: aqueous phase) of 1: 1 or more should be maintained with respect to the aqueous phase to which the extraction solvent is supplied to the extraction column in order to ensure proper extraction efficiency. However, as in the embodiment of the present invention, in the extraction process with a decanter, excellent extraction efficiency can be obtained even if the extraction solvent is maintained at a weight ratio of 1: 1 or less (for example, 0.8: 1) with respect to the aqueous phase supplied to the extraction column. have. In other words, it is possible to perform extraction for larger amounts of feed using the same amount of extraction solvent. As such, the amount of the extraction solvent introduced into the extraction process can be reduced, thereby reducing the amount of azeotropic solvent to be recovered in the subsequent distillation column 300, thereby reducing energy consumption.

However, even if the weight ratio of the extraction solvent exceeds 0.8: 2, the extraction efficiency may be improved, but when an excess amount of the extraction solvent is used, the amount of loss of (meth) acrylic acid in the distillation column 300 may increase, preventing it. The reflux flow of the azeotropic solvent for this can be excessively high, which is undesirable.

And, according to one embodiment of the invention, the temperature of the water phase supplied to the extraction column 200 is 10 to 7 (C is advantageous in terms of ensuring extraction efficiency.

As the extraction column 200 in the extraction process, a conventional extraction column according to the liquid-liquid contacting method may be used without particular limitation. As a 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 tower. tower, packed extraction tower, pulse packed column, and the like.

Through this extraction process, the (meth) acrylic acid extract is discharged to the upper portion of the extraction column 200, the discharged extract is supplied to the decanter 150 through the transfer line (215). That is, the (meth) acrylic acid extract obtained in the extraction column 200 is not directly supplied to the distillation column 300, but through the decanter 150. The phase separated organic phase is fed to distillation column 300. Then, the remaining balance is discharged to the lower portion of the extraction column 200, the discharged balance is supplied to the decanter 350 through the transfer line (235).

In this case, in addition to (meth) acrylic acid as the target compound, the extract may include an extraction solvent, water, and an organic by-product. Non-limiting examples, in the normal state and a stable operation is performed, the extract has a (meth) acrylate, 30 to 40 parts by weight ^_0/0, the extraction solvent 55 to 65 parts by weight ^_0/0, water, 1 to 5 parts by weight ^_0/0, and the remaining May include organic by-products. That is, most of the water (eg, 85% by weight or more of the water contained in the aqueous solution) contained in the (meth) acrylic acid aqueous solution may be recovered through the extraction process.

And, the balance obtained from the extraction column 200 may be made of mostly water, it may contain (meth) acrylic acid not extracted. However, according to one embodiment of the invention, the weight balance may contain (meth) acrylic acid having a concentration of 15% by weight or less or 3 to 15% by weight ⁰ /. Loss of acrylic acid can be minimized. ^'

Distillation process

Meanwhile, a distillation process of distilling a feed including the organic phase obtained through the phase separation process to obtain (meth) acrylic acid is performed.

In the embodiment as shown in FIG. 1, the feed is an organic phase separated in the decanter 150, which is fed from the decanter 150 to the distillation column 300 through the organic phase transfer line 153.

And, in the embodiment as shown in Figure 2, the feed may be a mixture of the organic phase supplied from the above-described phase separation process with the remainder of the aqueous (meth) acrylic acid solution supplied from the above-described absorption process. In this case, the feed may be fed together to a feed point of the distillation column 300 through the (meth) acrylic acid aqueous solution transfer line 130 and the organic phase transfer line 153.

At this time, in order to enable efficient distillation, the feed point to which the feed is supplied is advantageously the center of the distillation column 300, preferably, 40 to 60% of the entire stage from the top of the distillation column 300 on It may be any one point.

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 is heated to an appropriate temperature to allow distillation by evaporation and expansion.

At this time, in order to efficiently separate (meth) acrylic acid included in the feed from the remaining components (eg, water, acetic acid, extraction solvent, etc.), the distillation is preferably carried out by azeotropic distillation.

The solvent applied to the azeotropic distillation method can be azeotropic with water and acetic acid, preferably a hydrophobic azeotropic solvent that does not azeotropic with (meth) acrylic acid. In addition, the hydrophobic azeotropic solvent preferably has a lower boiling point (for example, 120 or less, or 10 to 120 ^° C., or 50 to 120 ° C.).

Specifically, the hydrophobic azeotropic solvent is benzene, toluene, xylene, n-heptane, n-heptane, cycloheptane, cycloheptene, 1-heptene ( 1-heptene), ethyl-benzene (ethyl-benzene), methyl-cyclopentane nucleic acid _{(me thyl-cyclc) hexane)} , n- butyl acetate (n-butyl acetate), isobutyl acetate (isobutyl acetate), isobutyl acrylate (isobutyl acrylate), n-propyl acetate, isopropyl acetate, methyl isobutyl ketone, 2-methyl-1 -heptene , 6-methyl-1 -heptene (6-methyl-1 -heptene),

4-methyl-1 -heptene (4-methyl-1 -heptene), 2-ethyl-1 -nuxene (2-ethy I -hexene), ethylcyclopentane (ethylcydopentane), 2-methyl-1 -nuxene (2- methyl-1 -hexene), 2,3-dimethylpentane, 5-methyl-1 -nuxene (5-methyl-1 -hexene), and isoprapyl-butyl-ether It may be one or more solvents selected from the group consisting of

In view of the production efficiency according to the continuous process, the hydrophobic azeotropic solvent is preferably the same as the extraction solvent of the extraction process. When the same kind of solvent is used in the extraction process and the distillation process as described above, at least a part of the solvent distilled from the distillation column 300 and recovered through the phase separation tank 350 is supplied to the (meth) acrylic acid extraction column 200. Can be reused as extraction solvent Can be.

Through such a distillation process, the remaining components except for (meth) acrylic acid in the feed are discharged to the top of the distillation column 300 with the azeotropic solvent, and (meth) acrylic acid is discharged to the bottom of the distillation column (300).

In this case, the upper discharge liquid of the distillation column 300 may be supplied to the decanter 350 to be reused after a predetermined treatment. As an example, the top discharge of the distillation column 300 may be separated into an organic phase including an azeotropic solvent and an aqueous phase including water in the decanter 350. Here, the separated organic phase can be fed to the top of the distillation column 300 and used as an azeotropic solvent. And, if necessary, at least a portion of the organic phase may be supplied to the extraction column 200 to be used as the extraction solvent. At least a portion of the aqueous phase separated from the decanter 350 may be supplied to the (meth) acrylic acid absorption tower 100 to be used as an absorption solvent, and some may be treated with wastewater. The acetic acid may be partially contained in the aqueous phase, and the concentration of acetic acid included in the aqueous phase may vary depending on the type of azeotropic solvent and the reflux ratio. Non-limiting examples, the concentration of acetic acid contained in the water phase may be 1 to 50 parts by weight ^_0/0, or 2 to 40 parts by weight ^_0/0, or from 3 to 30 wt. ^_0/0.

Meanwhile, the (meth) acrylic acid aqueous solution passes through the (meth) acrylic acid absorption tower 100, the decanter 150, the extraction column 200, and the distillation column 300, and the like. At least a portion of may form a dimer or oligomer. In order to minimize such polymerization of (meth) acrylic acid, a conventional polymerization inhibitor may be added to the distillation column 300.

In addition, the bottom discharge liquid of the distillation column 300 may include a high boiling point byproduct polymerization inhibitor such as a polymer of (meth) acrylic acid in addition to (meth) acrylic acid. Therefore, if necessary, the step of separating the high boiling by-products included in the bottom discharge liquid by supplying the bottom discharge liquid of the distillation column 300 to the high boiling point by-product separation tower 400 may be performed. And, crude (meth) acrylic acid (CAA) recovered through the above process may be obtained as a higher purity (meth) acrylic acid (HPAA) through an additional crystallization process. At this time, the high boiling point by-product separation process and crystallization process may be performed under conventional conditions. As such, the process conditions and the like are not particularly limited.

On the other hand, in such a method for recovering (meth) acrylic acid, each of the above-described steps can be performed organically and continuously. In addition to the above-described steps, processes that may be normally performed before, after, or simultaneously with each step may be further included and operated.

In the method for recovering (meth) acrylic acid according to the embodiment of the present invention, each of the above-described processes may be performed organically and continuously. In addition to the above-described processes, processes that may be normally performed before or after each process may be further performed. For example, the (meth) acrylic acid aqueous solution obtained in the (meth) acrylic acid absorption tower (100) is fed to a separate degassing column before feeding to the (meth) acrylic acid extraction column (200) to produce low boiling point by-products (acrolein, propionaldehyde). , Acetaldehyde, formaldehyde, isopropyl acetate, etc.) may be further performed. II. (Metro acrylic continuous recovery device

Meanwhile, according to another embodiment of the present invention,

A mixed gas inlet to which a mixed gas containing (meth) acrylic acid, organic by-products and water vapor produced by the synthesis reaction of (meth) acrylic acid is supplied, and 수용액 an aqueous (meth) acrylic acid solution obtained by contacting the mixed gas with water is discharged. (Meth) acrylic acid absorption tower 100 is provided with an aqueous solution outlet;

(Meth) acrylic acid aqueous solution inlet connected to the aqueous solution outlet of the absorption tower 100 and the aqueous solution transfer line (1 15), the extract liquid outlet of the extraction column 200 to be described later and (meth) connected through the extract liquid transfer line (215) A decanter (150) provided with an acrylic acid extract inlet, an introduced (meth) acrylic acid aqueous solution and an organic phase outlet through which an organic phase obtained by phase separation of the extract is discharged, and an aqueous phase outlet through which the aqueous phase obtained by phase separation is discharged;

The water outlet of the decanter 150 and the water inlet connected through the water transfer line 152, the extraction liquid outlet through which the (meth) acrylic acid extract obtained by contacting the introduced water phase and the extraction solvent is discharged, and the balance thereof is discharged. A (meth) acrylic acid extraction column (200) equipped with a drainage liquid outlet; And A distillation column with an (meth) acrylic acid outlet through which an organic phase inlet of the decanter 150 and an organic phase inlet connected through an organic phase transfer line 153 and a (meth) acrylic acid obtained by distillation of a feed including the introduced organic phase are discharged. (300)

Provided is a continuous recovery apparatus for (meth) acrylic acid.

The continuous recovery apparatus of (meth) acrylic acid according to the embodiment may be operated according to the above-described continuous recovery method of (meth) acrylic acid.

And, according to the _embodiment, the example of the invention, the distillation column 300, and the organic phase was transferred organic phase outlet of the aqueous solution inlet, the decanter 150 is connected through the solution outlet and the solution transfer line 130 of the absorber 100 An organic phase inlet connected via line 153 and a (meth) acrylic acid outlet through which (meth) acrylic acid obtained by distillation of a mixture of the introduced aqueous solution and the organic phase is discharged; A portion of the (meth) acrylic acid aqueous solution discharged from the absorption tower 100 may be supplied to the decanter 150, and the remainder of the (meth) acrylic acid aqueous solution may be supplied to the distillation column 300.

Basically, the (meth) acrylic acid recovery device includes a (meth) acrylic acid absorption tower 100, a (meth) acrylic acid extraction column 200, and a distillation column 300. In particular, in the apparatus according to the embodiment of the present invention, the aqueous (meth) acrylic acid solution discharged from the absorption tower 100 and the (meth) acrylic acid extract discharged from the extraction column 200 are supplied to the decanter 150. The organic phase recovered through phase separation in the decanter 150 is supplied to the distillation column 300 through the transfer line 153, and the aqueous phase is supplied to the extraction column 200 through the transfer line 152. That is, in the (meth) acrylic acid recovery apparatus, the absorption tower 100 and the extraction column 200 are connected via a decanter 150. Similarly, the extraction column 200 and the distillation column 300 are connected via a decanter 150. However, as shown in FIG. 2, the absorption tower 100 and the distillation column 300 may be directly connected through the (meth) acrylic acid aqueous solution transfer line 130.

Meanwhile, the (meth) acrylic acid absorption tower 100 may be a packed tower for improving the contact efficiency between the (meth) acrylic acid-containing mixed gas 1 and the absorption solvent. It may be a multistage tray tower. Here, the laminar tower may have a filler such as a rashing ring, a pall ring, a saddle, a gauze, a structured packing, or the like.

As the (meth) acrylic acid extraction column 200, a conventional extraction column according to a liquid-liquid contacting method may be applied without particular limitation. As a 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. column, packed extraction column, pulse packed column, and the like.

The distillation column 300 may be a pack column or a multi-stage column, preferably a sieve tray column and a dual flow tray column containing the above-described layering agent therein. .

In addition, the acetic acid absorption tower 50, decanters (150 and 350), various transfer lines, high boiling point by-product separation tower 400 and the like may have a conventional configuration in the art.

【Effects of the Invention】

The continuous recovery method of (meth) acrylic acid according to the present invention enables more stable operation and energy saving, and in particular, lowers the load of the extraction process for the (meth) acrylic acid aqueous solution, and increases feed throughput in the extraction process. It is possible to reduce the amount of extraction solvent used.

[Brief Description of Drawings]

1 and 2 schematically show a method and apparatus for continuously recovering (meth) acrylic acid according to embodiments of the present invention, respectively.

[Explanation of code]

1: (meth) acrylic acid-containing mixed gas

50: acetic acid absorption tower100: (meth) acrylic acid absorption tower

115, 130: (meth) acrylic acid aqueous solution transfer line

150, 350: decanter 152: decanter water transfer line

153: Organic Phase Transfer Line of Decanter

200: (meth) acrylic acid extraction column

215: extract feed line

235: balance transfer line

300: distillation column

400: high boiling point by-product separation tower

CAA: Crude (meth) acrylic acid

HPAA: High Purity (meth) acrylic Acid

[Specific contents to carry out invention]

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are only for illustrating the present invention, and the present invention is not limited thereto. Example 1

As shown in FIG. 1, a Reciprocating plate column equipped with a decanter 150 was prepared as an extraction column 200. The extraction column 200 has a total of 50 stages, a total height of 3 m, and an inner diameter of the column corresponding to the first to sixth stages (that is, the top six stages including the top stage) is 45 mm, and the remaining seventh stages to the third stage. The inner diameter of the column corresponding to 50 stages was the same as 22 mm. The free area ratio of the porous plates placed in the first to sixth stages is about 50% among the ^' perforated plates ^{' which} are placed at each stage of the extraction column 200 and repeat the vertical movement. The aperture ratios of the porous plates in the remaining seventh to fifty stages are about 28.3%, respectively.

Then, an aqueous acrylic acid solution (concentration of acrylic acid about 64 weight ⁰ /.) Was prepared as a feed, and toluene was prepared as an extraction solvent. The aqueous acrylic acid solution was fed to the decanter 150 together with the extract of the extraction column 200 and phase separated. And, the water phase separated in the decanter 150 (acrylic acid concentration of about 5 weight ⁰ /.) Was fed to the extraction column 200, the remaining organic phase was fed to the distillation column (300). At this time, the Solvent / Feed ratio in the extraction column 200 was maintained at about 1.3.

And the continuous phase (organic phase) associated with the feed throughput of the extraction column 200. Increase the linear velocity to 0.4 cm / s, 0.5 cm / s, 0.6 cm / s, 0.8 cm / s, and 1.0 cm / s, respectively, with the maximum extraction rate of acrylic acid ([mass of acrylic acid in the extract] / [ Mass of acrylic acid included] ^* 100). At this time, the maximum extraction rate at each linear velocity was measured under the conditions of the maximum mechanical repetition rate (rpm; that is, the maximum rpm immediately before the flooding phenomenon) of the porous plate, and the results are shown in Table 1 below. Comparative Example 1

Except that the decanter 150 was not provided, a column having the same specifications as the Reciprocating plate cc) lumn used in Example 1 was prepared as an extraction column.

And an acrylic acid aqueous solution (concentration of acrylic acid about 64 weight ⁰ /.) Was prepared as a feed, and toluene was prepared as an extraction solvent. The aqueous acrylic acid solution and toluene were supplied to the feed inlet (corresponding to the aqueous inlet of Example 1) and the solvent inlet of the extraction column. Then, the extract obtained in the extraction column was fed to the distillation column. At this time, the S vent / Feed ratio was maintained at about 1.3 in the extraction column.

And increasing the linear velocity of the continuous phase (organic phase) associated with the feed throughput of the extraction column to 0.2 cm / s, 0.4 cm / s, 0.6 cm / s, 0.7 cm / s and 0.8 cm / s, respectively. The maximum extraction rate of acrylic acid was measured in the same manner as in Example 1. The results are shown in Table 2 below.

Table 1 1

Table 2

Referring to Table 2, Comparative Example 1 exhibited a maximum extraction rate of 99.46 ⁰ /. When the linear velocity of the organic phase in the extraction column was operated at a low 0.4 cm / s. However, in Comparative Example 1, when the linear velocity of the organic phase was increased to 0.8 cm / s, the maximum operable rpm of the porous plate was decreased. That is, in Comparative Example 1, as the feed throughput per unit time increased, flooding occurred at a relatively low rpm, and the extraction rate of acrylic acid was also decreased.

On the other hand, referring to Table 1, Example 1 was able to set the linear velocity of the organic phase in a higher range compared to Comparative Example 1 by using an extraction column equipped with a decanter. In particular, when the linear velocity of the organic phase in Example 1 is 0.8 cm / s, the feed throughput per unit time is twice as high as in the comparative example 1 when the linear velocity of the organic phase is 0.4 cm / s. Mechanical agitation was possible, indicating an acrylic acid extraction rate of at least equal. In addition, when comparing the case where the linear velocity of the organic phase is 0.6 cm / s, it was confirmed that Example 1 was able to operate even under the condition of up to 165 rpm, it was possible to exhibit the highest acrylic acid extraction rate. Example 2

In the extraction column 200, except that S adjusts the vent / Feed ratio to 1 or 1.3 and the linear velocity of the continuous phase (organic phase) associated with the feed throughput of the extraction column 200 is fixed at 0.5 cm / s, In the same manner as in Example 1, the maximum extraction rate of acrylic acid was measured. The results are shown in Table 3 below. Comparative Example 2

Except that the decanter 150 was not provided, a column of the same size as the Reciprocating plate ∞lumn used in Example 1 was prepared as an extraction column.

And adjusting the solvent / feed ratio in the extraction column to 1 or 1.3 and fixing the linear velocity of the continuous phase (organic phase) associated with the feed throughput of the extraction column to 0.5 cm / s. In the same way, the maximum extraction rate of acrylic acid was measured. The results are shown in Table 4 below.

Table 3

When the solvent / Feed ratio was lowered, the maximum rpm that could be operated increased, but the extraction rate of acrylic acid decreased by more than 1% due to the increase of the acrylic acid concentration in the balance.

On the other hand, referring to Table 3, in case of lowering the Sc) lvent / Feed ratio in Example 2 can be operated at the same rpm as Comparative Example 2, while the extraction rate of acrylic acid is almost _. It has been shown that it can be maintained without falling off. In other words, in order to increase the processing capacity of the feed to increase the production of acrylic acid, using an extraction column equipped with a decanter as in the above embodiments, It has been found that by adjusting the flow, it is possible to increase the flexibility of the process operation without changing the volume of the extraction column. Furthermore, according to the method of the embodiments, it can be operated by reducing the Solvent / Feed ratio, it is possible to reduce the amount of solvent used, and to reduce the energy consumption in the distillation process.

Claims

[Claim]

[Claim 1]

An absorption step of bringing a mixed gas comprising (meth) acrylic acid, organic by-products and water vapor generated by the synthesis reaction of (meth) acrylic acid into water in a (meth) acrylic acid absorption tower to obtain an aqueous (meth) acrylic acid solution;

An extraction step of contacting the aqueous phase obtained through the phase separation step with an extraction solvent in an extraction column to obtain a (meth) acrylic acid extract and an extract; And

Continuous recovery method of (meth) acrylic acid containing a.

[Claim 2]

The method of claim 1,

A distillation process of distilling a feed including the remainder of the aqueous (meth) acrylic acid solution obtained through the absorption process and the organic phase obtained through the phase separation process to obtain (meth) acrylic acid.

Continuous recovery method of (meth) acrylic acid containing a.

[Claim 3]

According to claim 1,

The organic phase obtained by phase-separation in the said decanter is a method for continuous recovery of (meth) acrylic acid, containing (meth) acrylic acid of at least 40% of (meth) acrylic acid contained in the (meth) acrylic acid aqueous solution and the (meth) acrylic acid extract .

[Claim 4]

A mixed gas inlet supplied with a mixed gas containing (meth) acrylic acid, organic by-products and water vapor produced by the synthesis reaction of (meth) acrylic acid, and an aqueous (meth) acrylic acid solution obtained by contacting the mixed gas with water is discharged. (Meth) acrylic acid absorption tower 100 is provided with an aqueous solution outlet;

The water outlet of the decanter 150 and the water inlet connected through the water transfer line 152, the extraction liquid outlet through which the (meth) acrylic acid extract obtained by contacting the introduced water phase and the extraction solvent is discharged, and the balance thereof is discharged. A (meth) acrylic acid extraction column (200) equipped with a drainage liquid outlet; And

A distillation column having an organic phase inlet connected to the organic phase outlet of the decanter 150 and an organic phase inlet connected through the organic phase transfer line 153 and a (meth) acrylic acid outlet through which (meth) acrylic acid obtained by distillation of a feed including the introduced organic phase is discharged. (300)

A continuous recovery apparatus of (meth) acrylic acid, including.

[Claim 5]

The method of claim 4,

The distillation column 300 has an aqueous solution outlet and an aqueous solution of the absorption tower 100 Obtained by distillation of the aqueous solution inlet connected via transfer line 130, the organic phase outlet of the decanter 150 and the organic phase inlet connected via organic phase transfer line 153, and the mixture of the introduced aqueous solution and organic phase (meth) A (meth) acrylic acid outlet through which acrylic acid is discharged;

A part of the (meth) acrylic acid aqueous solution discharged from the absorption tower 100 is supplied to the decanter 150, and the remainder of the (meth) acrylic acid aqueous solution is operated to be supplied to the distillation column 300, (meth) Continuous recovery device of acrylic acid.