KR20150011634A

KR20150011634A - Process for continuous recovering (meth)acrylic acid and apparatus for the process

Info

Publication number: KR20150011634A
Application number: KR1020130086830A
Authority: KR
Inventors: 백세원; 송종훈; 유설희; 민윤재
Original assignee: 주식회사 엘지화학
Priority date: 2013-07-23
Filing date: 2013-07-23
Publication date: 2015-02-02

Abstract

The present invention relates to a continuous recovery method of (meth)acrylic acid and to a device used in the method. According to the present invention, the continuous recovery method of (meth)acrylic acid introduces an extraction process between a process of absorbing (meth)acrylic acid and a process of separating a solvent, thereby drastically lowering energy consumed in separating the solvent. Specifically, the continuous recovery method of (meth)acrylic acid recirculates a raffinate of the extraction process, uses the same as an absorption solvent, and removes solid slurry by filtering the raffinate, thereby providing improved absorption efficiency and operation stability.

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 recovered as an aqueous (meth) acrylic acid solution in contact with an absorption solvent such as process water in a (meth) acrylic acid absorption tower. 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 by passing through an extraction tower, a water separation column and the like 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, there is known a method of azeotropically distilling using a hydrophobic solvent in a water separation column. In another method, there is known a method of supplying energy to a (meth) acrylic acid aqueous solution to an extraction column to obtain a (meth) acrylic acid extract and a residual liquid with reduced water content, and distilling the extracted liquid.

On the other hand, the (meth) acrylic acid aqueous solution obtained from the (meth) acrylic acid absorption tower contains various organic byproducts such as maleic acid, terephthalic acid, aldehyde and (meth) acrylic acid polymer in addition to (meth) acrylic acid. However, due to the characteristics of the continuous process, the water-insoluble materials in the organic by-products are precipitated in the form of a slurry to contaminate the absorption tower, the extraction tower, etc., and accumulate in the internal filler of the absorption tower to prevent efficient recovery of (meth) .

The present invention relates to a continuous recovery method of (meth) acrylic acid, which can secure a recovery rate of (meth) acrylic acid equal to or higher than that of the previous recovery method, .

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

According to the present invention,

(Meth) acrylic acid is obtained by contacting a mixed gas containing (meth) acrylic acid, an organic by-product and water vapor produced by a synthesis reaction of (meth) acrylic acid with water in a (meth) acrylic acid absorption tower 100, (Meth) acrylic acid extraction tower 200,

(Meth) acrylic acid aqueous solution supplied to the (meth) acrylic acid extraction tower 200 with an extraction solvent to extract the (meth) acrylic acid and supplying the obtained extracted phase to the water separation tower 300, and

Distilling the extracted phase fed to the water separation column 300 to obtain (meth) acrylic acid;

(Meth) acrylic acid absorption tower 100 to remove the solid slurry contained in the residue after filtering the residual residue of the (meth) acrylic acid extraction tower 200 and supply the filtrate to the upper end of the (meth) A recovery method is provided.

According to the present invention, the post-residual filtering may be performed using a filter 250 having pores having an average diameter of 50 mu m or less.

According to the present invention, it is preferable that at least 80% by weight of the solid slurry contained on the residue is removed by the filtering.

On the other hand, the synthesis reaction of (meth) acrylic acid may be carried out by carrying out an oxidation reaction of at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, t-butylene and (meth) acrolein under a gas phase catalyst .

The (meth) acrylic acid aqueous solution obtained from the (meth) acrylic acid absorption tower 100 may contain (meth) acrylic acid in a concentration of 40 to 90% by weight.

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 transfer line 102 connected to supply the (meth) acrylic acid aqueous solution to the (meth) acrylic acid extraction tower 200;

A (meth) acrylic acid extraction tower 200 for obtaining an extraction phase containing (meth) acrylic acid by contacting the (meth) acrylic acid aqueous solution with an extraction solvent and obtaining a residual image;

An extracted phase transfer line 203 connected to supply the extracted phase to the water separation tower 300;

A water separation tower 300 for distilling the extracted phase to obtain (meth) acrylic acid;

A filter 250 for filtering the residual residual image to remove the solid slurry contained in the residual residue; And

The filtrate transfer line 201 connected to supply the filtered filtrate to the upper end of the (meth) acrylic acid absorption tower 100,

(Meth) acrylic acid.

The continuous recovery method of (meth) acrylic acid according to the present invention can greatly reduce the energy consumed in solvent separation by introducing an extraction step between the (meth) acrylic acid absorption step and the solvent separation step. Particularly, in the continuous recovery method of (meth) acrylic acid according to the present invention, the residual residue of the extraction process is recycled to the absorption process and used as an absorption solvent. By filtering the residual residue to remove the solid slurry, Thereby providing stability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram schematically showing a continuous recovery method of (meth) acrylic acid according to an embodiment of the present invention. FIG.
Figs. 2 to 4 are photographs showing the state of the absorption solvent recycled from the (meth) acrylic acid extraction column to the (meth) acrylic acid absorption column in the method according to the embodiment of the present invention or the comparative example.

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 produced when (meth) acrylic acid is produced by a gas phase oxidation reaction. That is, according to one embodiment of the present invention, at least one compound selected from the group consisting of propane, propylene, butane, i-butylene, t-butylene and (meth) acrolein (Meth) acrylic acid-containing mixed gas. (Meth) acrylic acid, unreacted raw material compound, (meth) acrolein, 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. Here, the term "light ends" or "high boiling point byproducts" refers to a kind of by-product that can be produced in the production and recovery of a desired (meth) acrylic acid, Small or large compounds are collectively referred to.

The term " feed " means a liquid mixture containing a solute to be extracted, and includes a solute having solubility in an extraction solvent and other ingredients having no solubility (inert material ). &Lt; / RTI > Here, when the extraction solvent is added to the feed, the solute is dissolved in the extraction solvent from the feed by the mass transfer phenomenon. Hence, the extraction solvent in which a significant amount of the solute is dissolved forms an extract, and the feed which has lost a considerable amount of solute forms a raffinate.

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

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, the inventors of the present invention have found that, in the course of research on a continuous recovery method of (meth) acrylic acid, the method of recovering (meth) acrylic acid through the previously disclosed azeotropic distillation method is a method of recovering (meth) acrylic acid from a water separation tower (or distillation tower) It has been confirmed that not only a very large amount of energy is consumed but also the stability of the process operation is deteriorated due to the production of the polymer by polymerization of (meth) acrylic acid in the distillation process.

(Meth) acrylic acid extraction tower 200 is disposed between the (meth) acrylic acid absorption tower 100 and the water separation tower 300 as shown in FIG. 1, It is confirmed that the operational burden of the water separation tower 300 can be greatly reduced. Further, the residual residue of the extraction column 200 is recycled to the absorption column 100 to be used as an absorption solvent. By removing the residual slurry by filtering the residual residue, more improved absorption efficiency and operational stability can be provided Respectively.

According to an embodiment of the present invention,

Hereinafter, with reference to FIG. 1, each step included in the recovery method of the embodiment will be described.

I. Absorption Process

(Meth) acrylic acid absorption tower 100, the aqueous solution obtained is added to the (meth) acrylic acid extraction tower 200, and the resulting (meth) .

The (meth) acrylic acid aqueous solution can be obtained according to a conventional method in the technical field of the present invention, and the specific method is not particularly limited. However, according to the present invention, the step (a) may include a step in which a mixed gas containing (meth) acrylic acid, organic by-products and water vapor generated by the synthesis reaction of (meth) To obtain an aqueous (meth) acrylic acid solution.

The synthesis reaction of (meth) acrylic acid is carried out by a method of oxidizing at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, t-butylene and (meth) .

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. However, the gas-phase oxidation reaction in the present invention is not limited to the above examples.

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 by-products, high boiling point by-products, etc.), and the like.

According to one embodiment, the (meth) acrylic acid-containing mixed gas (1) is supplied to the (meth) acrylic acid absorption tower (100) and brought into contact with water as an absorption solvent to obtain .

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

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 a small amount of organic by-products (e.g., acetic acid) introduced from another process. According to one embodiment of the present invention, the absorption amount of the (meth) acrylic acid absorption tower 100 The solvent may contain organic by-products at a concentration of 3-15% by weight. 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.

Further, according to the present invention, the after-residue image obtained in the (meth) acrylic acid extraction tower 200 to be described later can be recycled to the (meth) acrylic acid absorption tower 100 and used as an absorption solvent. At this time, it is advantageous in terms of improvement of process efficiency that the residual residual image is supplied to the upper end of the absorption tower 100.

On the other hand, the (meth) acrylic acid absorption tower 100 can be operated at an internal pressure of 1 to 1.5 bar, preferably 1 to 1.3 bar, in consideration of condensation conditions of (meth) acrylic acid and moisture content conditions depending on saturated steam pressure And the internal temperature thereof can be adjusted to 50 to 100 캜, preferably 50 to 80 캜.

Through the above 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 having the (meth) acrylic acid deaerated is discharged to the upper part.

At this time, 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 resulting (meth) acrylic acid aqueous solution is supplied to the (meth) acrylic acid extraction tower 200 through the transfer line 102.

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 extraction tower 200 is brought into contact with an extraction solvent to extract acrylic acid, and the resulting acrylic acid is extracted with an extraction solvent to obtain a (meth) And supplying the extracted extracted phase to the water separation tower 300.

In the (meth) acrylic acid extraction tower 200, the (meth) acrylic acid aqueous solution as a feed is contacted with an extraction solvent to produce a substantial amount of an extract of (meth) acrylic acid and an aqueous solution of (meth) And are discharged as raffinate, which is lost.

In this connection, the conventional (meth) acrylic acid recovery method is a method in which the (meth) acrylic acid aqueous solution obtained in the (meth) acrylic acid absorption tower 100 is supplied to the water separation tower 300 and distilled. However, the recovery method of this embodiment is a method in which the (meth) acrylic acid aqueous solution is supplied to the (meth) acrylic acid extraction tower 200 and extracted, and then the extracted phase having the minimum water content is distilled from the water separation tower 300 According to the method.

At this time, in the extraction column 200, most of the water contained in the aqueous solution can be removed through a method of contacting an aqueous (meth) acrylic acid solution with an extraction solvent (that is, a method in which a large amount of energy is not required) . Accordingly, the burden on the distillation treatment in the subsequent stage of the water separation tower 300 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 step, can be minimized, so that improved operation stability can be secured.

Particularly, in the extraction step, the residual slurry of the (meth) acrylic acid extraction tower 200 is filtered to remove the solid slurry contained in the residue, and the filtrate is supplied to the upper end of the (meth) acrylic acid absorption tower 100 . That is, in the continuous recovery method of (meth) acrylic acid according to one embodiment, the residual residue of the extraction process is recycled to the absorption process and used as an absorption solvent. By filtering the residual residue to remove the solid slurry, And the stability of operation.

The residue may include water, acetic acid, a hardly water-soluble solid slurry, and some (meth) acrylic acid which is not extracted. Among them, the poorly water-soluble solid slurry can be precipitated in a (meth) acrylic acid aqueous solution due to the difference in solubility of the organic by-products in the (meth) acrylic acid aqueous solution and the (meth) acrylic acid extract solution during the operation of the extraction tower 200. The poorly water-soluble solid slurry may contain maleic acid, maleic anhydride, terephthalic acid, aldehyde, succinic acid anhydride, dioctyl phthalate, (meth) acrylic acid polymer, etc. and may contain some (meth) acrylic acid and have.

When such a solid slurry is introduced as the absorbing solvent of the absorber 100 in the state of being contained in the residual residue, absorption efficiency of the (meth) acrylic acid may be lowered by being deposited on the inner filler of the absorber 100, The continuous operation of the absorption tower 100 may become impossible. Therefore, as in the above-described embodiment, it is preferable to filter the residual residue to remove the solid slurry, thereby preventing a decrease in the absorption efficiency and ensuring an improved operation stability.

In order to achieve a substantial effect through the filtering on the residual image, it is preferable that at least 80 wt% or at least 90 wt% of the solid slurry contained in the residual residue is removed by the filtering .

The filtering on the residual image can be performed to such an extent that the solid slurry contained on the residual image can be separated at the removal rate. The method, the configuration of the filter, and the like are not particularly limited. However, according to one embodiment, the filter 250 may have pores having an average diameter of 50 占 퐉 or less, or 0.1 to 30 占 퐉, or 0.5 to 20 占 퐉. That is, in order to sufficiently remove the solid slurry contained in the residue, it is advantageous that the filter 250 has pores with an average diameter of 50 μm or less. In consideration of the filtering efficiency and the process flow, it is advantageous for the filter 250 to have pores with an average diameter of 0.1 占 퐉 or more.

And, the filter 250 may include one or more filters satisfying the above configuration, and a sufficient effect can be achieved with only one filter. When two or more filters are used, the filter 250 may be mounted in the form of a series of filters having pores having different average diameters, which may be more advantageous from the viewpoint of improving the filtering efficiency.

The filter 250 may be located where the residual residue obtained in the extraction tower 200 can be filtered before being supplied to the absorption tower 100. As a non-limiting example, the filter 250 may be connected directly to the extraction tower 200 or absorber 100.

On the other hand, the extraction solvent supplied to the extraction tower 200 may be soluble in (meth) acrylic acid and hydrophobic. However, in view of the physical properties of the azeotropic solvent required in the water separation column 300, which is a subsequent process, it is preferable that the extraction solvent has a boiling point lower than that of (meth) acrylic acid. For example, the extraction solvent may be a hydrophobic solvent having a boiling point of 120 占 폚 or lower, or 10 to 120 占 폚, or 50 to 120 占 폚.

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.

In the extraction step, the temperature of the (meth) acrylic acid aqueous solution is advantageously 10 to 70 ° C in terms of improvement in process 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 extracted phase is discharged to the upper part of the extraction tower 200, and the extracted phase is supplied to the water separation tower 400 through the transfer line 203. The residual residual phase is discharged to the lower part of the extraction tower 200 and the residual residual phase is recycled to the (meth) acrylic acid absorption tower 100 through the transfer line 201.

At this time, the extraction phase may contain an extraction solvent, water, and organic by-products in addition to (meth) acrylic acid as a target compound. According to one embodiment, in a steady state where stable operation has been performed, the extraction phase comprises 30-40 wt% of (meth) acrylic acid, 55-65 wt% of extraction solvent, 1-5 wt% of water, . That is, most of the water (for example, 95% by weight or more) contained in the (meth) acrylic acid aqueous solution through the extraction step can be recovered as residual residue. As most of the water is recovered in the extraction tower 200, the energy consumption can be reduced by reducing the distillation burden of the water separation tower 300, the distillation conditions can be relaxed, and operation stability can be ensured.

The residual residue obtained from the extraction tower 200 is mostly composed of water and may contain some (meth) acrylic acid which is not extracted. According to one embodiment, the (meth) acrylic acid may be contained in the residue on 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 this embodiment, the concentration of (meth) acrylic acid contained on the residue is as low as 5% by weight or less, and the loss of (meth) acrylic acid in the absorption tower 100 and the extraction tower 200 Can be minimized.

III . Distillation process

On the other hand, the continuous recovery method of (meth) acrylic acid according to this embodiment includes distilling the extracted phase supplied to the water separation column 300 to obtain (meth) acrylic acid.

The distillation step is a step of azeotropically distilling the extracted phase supplied from the (meth) acrylic acid extraction tower 200 through the transfer line 203 to the water separation column 300, and separating the water, the organic by- And the like to recover (meth) acrylic acid.

As described above, the conventional (meth) acrylic acid recovery method is a method in which the (meth) acrylic acid aqueous solution obtained in the (meth) acrylic acid absorption tower 100 is fed to the water separation tower 300 and distilled. On the other hand, in the recovery method of this embodiment, the (meth) acrylic acid aqueous solution is supplied to the (meth) acrylic acid extraction tower 200 and extracted, and the extracted phase having the minimum water content is extracted from the water separation tower 300 It depends on the method of distillation. Accordingly, the distillation burden in the water separation column 300 can be reduced. Further, the temperature in the vicinity of the extraction phase introduction part can be kept low in the water separation tower 300, and the polymerization reaction of (meth) acrylic acid can be minimized during distillation. Furthermore, the energy consumption used in the distillation process can be minimized and the energy efficiency of the entire process can be further improved.

According to this embodiment, the distillation in the water separation column 300 can be carried out in the presence of a hydrophobic azeotropic solvent. That is, the azeotropic distillation using the hydrophobic azeotropic solvent is advantageous in that water, organic by-products and solvent can be simultaneously recovered.

Here, the hydrophobic azeotropic solvent may have 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.

The hydrophobic azeotropic solvent may be the same as the extraction solvent applied to the extraction tower 200 in consideration of the production efficiency according to 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 and recovered in the water separation column 300 is supplied to the lower end of the (meth) acrylic acid extraction column 200, Can be reused.

The water separation tower 300 may be a packed tower or a multistage tray tower.

On the other hand, when the extracted phase and the hydrophobic azeotropic solvent are introduced into the water separation column 300 and heated to an appropriate temperature, the components other than (meth) acrylic acid (water, acetic acid, solvent, etc.) And is recovered to the upper part of the water separation tower 300 in an azeotropic manner together with the solvent. The (meth) acrylic acid is discharged to the lower portion of the water separation tower 300.

At this time, the upper effluent of the water separation column 300 is supplied to the phase separation tank 350 and can be reused after a predetermined treatment. Here, the phase separation tank 350 is an apparatus for separating a liquid phase which is not mixed with each other by using gravity or centrifugal force. The relatively light liquid is directed to the upper portion of the phase separation tank 350, (Not shown). As an example, the upper discharge liquid supplied to the phase separation tank 350 may be separated into an organic layer containing a hydrophobic azeotropic solvent and an aqueous layer containing water. At least a part of the organic layer separated from the phase separation tank 350 may be supplied to the upper end of the water separation tower 300 and used as an azeotropic solvent. The remainder of the organic layer may be supplied to the (meth) acrylic acid extraction column 200 as needed and used as an extraction solvent. At least a part of the water layer separated in the phase separation tank 350 may be supplied to the (meth) acrylic acid absorption tower 100 and used as an absorption solvent, and a part thereof may be treated with waste water.

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

In addition, crude (meth) acrylic acid is discharged to the lower part of the water separation column 300, and may be fed to an additional purification process if necessary.

The (meth) acrylic acid aqueous solution is passed through the (meth) acrylic acid absorption tower 100, the (meth) acrylic acid extraction tower 200, the water separation tower 300, A part of them 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 water separation column 300.

Meanwhile, the lower effluent of the water separation 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, the lower effluent of the water separation column 300 may be supplied to the high boiling point byproduct separation column 400 to separate the high boiling point byproducts contained in the lower effluent. The crude (meth) acrylic acid (CAA) can be obtained as a (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 reaction 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 can be further performed.

Meanwhile, according to another embodiment of the present invention,

(Meth) acrylic acid.

That is, in the apparatus of this embodiment, the (meth) acrylic acid absorption tower 100 is basically connected to the (meth) acrylic acid extraction tower 200 through the (meth) acrylic acid aqueous solution transfer line 102. The (meth) acrylic acid extraction tower 200 is connected to the water separation tower 300 through the (meth) acrylic acid extract liquid transfer line 203.

In particular, the apparatus of one embodiment includes a filter 250 for filtering the residual residue obtained in the (meth) acrylic acid extraction tower 200, and a filter 250 for filtering the filtered filtrate to be supplied to the upper end of the (meth) acrylic acid absorption tower 100 And a filtrate transfer line 201.

Here, the filter 250 is of such a degree as to be able to separate the solid slurry contained on the residual residue, and the specific structure thereof is not particularly limited. However, according to one embodiment, the filter 250 may have pores having an average diameter of 50 占 퐉 or less, or 0.1 to 30 占 퐉, or 0.5 to 20 占 퐉. That is, in order to sufficiently remove the solid slurry contained in the residue, it is advantageous for the filter 250 to have pores with an average diameter of 50 μm or less. In consideration of the filtering efficiency and the process flow, it is advantageous for the filter 250 to have pores with an average diameter of 0.1 占 퐉 or more. The filter 250 may be mounted in the form of a series of two or more filters having pores having different average diameters, which may be more advantageous from the viewpoint of improving the filtering efficiency. And, the filter 250 may include one or more filters satisfying the above configuration, and a sufficient effect can be achieved with only one filter. When two or more filters are used, the filter 250 may be mounted in the form of a series of filters having pores having different average diameters, which may be more advantageous from the viewpoint of improving the filtering efficiency.

The (meth) acrylic acid absorption tower 100 may be a packed tower or a multi-stage tray for improving the contact efficiency between the (meth) acrylic acid-containing mixed gas (1) multistage tray tower.

The filling tower may be filled with a filler such as a rashing ring, a pall ring, a saddle, a gauze, or a structured packing.

As the (meth) acrylic acid 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.

The water separating column 300 may be a pack column or a multi-column column, preferably a sieve tray column or a dual flow tray column, have.

In addition, the acetic acid absorption tower 150, the (meth) acrylic acid aqueous solution transfer line 102, the extracted phase transfer line 203, the phase separation tank 350, the high boiling point byproduct separation tower 400, And the like may be those having a conventional configuration in the technical field to which the present invention belongs.

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.

Example One

(Meth) acrylic acid extraction column 200 is introduced between the (meth) acrylic acid absorption tower 100 and the water separation column 300 and the residual residue obtained in the (meth) acrylic acid extraction column 200 is filtered Methacrylic acid absorption tower 100, a continuous recovery device having the same configuration as that of FIG. 1 was prepared, and the following process was continuously performed to verify the energy saving effect and the operation stability improvement effect.

A mixed gas obtained through the oxidation reaction of propylene was prepared. The composition of the mixed gas was about 16.6 wt% of acrylic acid, about 0.3 wt% of acrolein, about 0.5 wt% of acetic acid, about 0.3 wt% of unreacted propylene, about 2.6 wt% of carbon dioxide and carbon monoxide, about 10.1 wt% 69.3 wt.%, And about 0.3 wt.% Of high boiling point byproduct.

The acrylic acid absorption tower (100) was a 10-stage tray with a theoretical number of stages, and the internal temperature was adjusted to 50 to 100 占 폚. The mixed gas was supplied to the bottom of the absorber 100 at a temperature of about 160 DEG C, a pressure of about 1.3 bar, and a flow rate of about 62,860 kg / h. The process water, which is an acrylic acid absorption solvent, was supplied to the top of the absorption tower 100.

Then, an acrylic acid aqueous solution (composition: about 65.4% by weight of acrylic acid, about 2.4% by weight of acetic acid, about 30.2% by weight of water, and about 2.0% by weight of other components) was obtained as the lower part of the absorption tower 100. The acrylic acid aqueous solution was supplied to the acrylic acid extraction tower 200 through the transfer line 102.

A reciprocating multi-stage extraction tower (inner diameter: 22 mm, total 56 stages) was prepared from the acrylic acid extraction tower (200). The acrylic acid aqueous solution was introduced into the first stage which is the uppermost stage of the extraction tower 200. A part of the reflux stream containing toluene obtained as the organic layer in the upper discharge liquid of the water separation column 300 was used as the extraction solvent of the extraction tower 200.

After the stable operation was performed, the extracted phase was obtained at the upper part of the extraction tower 200 in the steady state, and the residual image was obtained at the lower part of the extraction tower 200. Wherein the extracted phase comprised about 64.8 weight percent toluene, about 32.9 weight percent acrylic acid, about 1.6 weight percent water, and about 0.7 weight percent acetic acid. The residual image includes 95.1% by weight of water, about 1.8% by weight of acrylic acid, about 0.7% by weight of acetic acid, and about 2.4% by weight of high-boiling by-products containing solid slurries.

The extracted phase was supplied to the water separation tower 300 through the transfer line 203. The residual residue was supplied to the filter 250 having pores having an average diameter of about 11 μm and filtered, and the filtered filtrate was supplied to the upper end of the absorption tower 100 through the transfer line 201.

It was confirmed through filtration that about 80% by weight of the solid slurry present in the residue after removal was removed. Then, as shown in Fig. 2, the filtered filtrate was visually observed, and only fine scum particles were observed at the interface.

Meanwhile, a dual flow tray pilot column (inner diameter 30 mm, total 28 stages) was prepared as the water separation tower 300, and the operation pressure was maintained at about 110 torr. The extracted phase was introduced into the 14th stage from the uppermost stage of the water separation tower 300 and a part of the reflux stream separated from the phase separation tank 350 was introduced into the first stage which is the uppermost stage of the water separation tower 300 . Water and acetic acid contained in the toluene, the extracted phase were discharged to the upper end of the water separation column 300, and crude acrylic acid was discharged to the lower end.

Example 2

An acrylic acid continuous recovery process was performed in the same manner as in Example 1, except that a filter 250 having pores having an average diameter of about 1 mu m was used.

As a result, it was confirmed that about 93% by weight of the solid slurry present in the residue after removal was removed through the above filtering. Then, as shown in Fig. 3, the filtered filtrate was visually observed, and no floating matter was found at the interface.

Comparative Example One

An acrylic acid continuous recovery process was performed in the same manner as in Example 1, except that a device without the filter 250 was used.

As shown in FIG. 4, the residual residue of the acrylic acid extraction column 200 was visually observed. As a result, it was confirmed that the solid slurry contained in the residual residue flocculates and floated on the interface.

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 tower
201: filtrate transfer line
203: Extraction phase transfer line
250: Filter
300: Water separation tower
350: phase separation tank
400: High boiling point byproduct separation tower
CAA: Jo (meth) acrylic acid
HPAA: High purity (meth) acrylic acid

Claims

(Meth) acrylic acid is obtained by contacting a mixed gas containing (meth) acrylic acid, an organic by-product and water vapor produced by a synthesis reaction of (meth) acrylic acid with water in a (meth) acrylic acid absorption tower 100, (Meth) acrylic acid extraction tower 200,
(Meth) acrylic acid aqueous solution supplied to the (meth) acrylic acid extraction tower 200 with an extraction solvent to extract the (meth) acrylic acid and supplying the obtained extracted phase to the water separation tower 300, and
Distilling the extracted phase fed to the water separation column 300 to obtain (meth) acrylic acid;
(Meth) acrylic acid absorption tower 100 to remove the solid slurry contained in the residue after filtering the residual residue of the (meth) acrylic acid extraction tower 200 and supply the filtrate to the upper end of the (meth) Recovery method.

The method according to claim 1,
The method for continuous recovery of (meth) acrylic acid according to claim 1, wherein the filtering of the residual image is performed using a filter (250) having pores having an average diameter of 50 m or less.

The method according to claim 1,
(Meth) acrylic acid, wherein at least 80% by weight of the solid slurry contained in the residual slurry is removed by the filtering.

The method according to claim 1,
The synthesis reaction of (meth) acrylic acid is carried out in the presence of at least one compound selected from the group consisting of (meth) acrylic acid and methacrylic acid, wherein at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, A continuous recovery method of acrylic acid.

The method according to claim 1,
Wherein the (meth) acrylic acid aqueous solution obtained from the (meth) acrylic acid absorption tower (100) contains (meth) acrylic acid in a concentration of 40 to 90% by weight.

The method according to claim 1,
Wherein the extraction solvent is a hydrophobic solvent having a boiling point of 10 to 120 캜.

(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 transfer line 102 connected to supply the (meth) acrylic acid aqueous solution to the (meth) acrylic acid extraction tower 200;
A (meth) acrylic acid extraction tower 200 for obtaining an extraction phase containing (meth) acrylic acid by contacting the (meth) acrylic acid aqueous solution with an extraction solvent and obtaining a residual image;
An extracted phase transfer line 203 connected to supply the extracted phase to the water separation tower 300;
A water separation tower 300 for distilling the extracted phase to obtain (meth) acrylic acid;
A filter 250 for filtering the residual residual image to remove the solid slurry contained in the residual residue; And
The filtrate transfer line 201 connected to supply the filtered filtrate to the upper end of the (meth) acrylic acid absorption tower 100,
(Meth) acrylic acid.

8. The method of claim 7,
Wherein the filter (250) has pores with an average diameter of 50 mu m or less.