JP2009249302A - Method for recovering (meth)acrylate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering a (meth)acrylate, by which a lower alcohol can be separated from a (meth)acrylate solution containing the lower alcohol, to efficiently recover the (meth)acrylate. <P>SOLUTION: Provided is a method for recovering the (meth)acrylate, comprising recovering the (meth)acrylate containing the lower alcohol with a water-lower alcohol azeotropic solvent, characterized by adding and distilling at least the lower alcohol azeotropic solvent to the (meth)acrylate solution containing the lower alcohol to separate the lower alcohol in a water layer and separate the lower alcohol azeotropic solvent in an oil layer, to thereby recover the (meth)acrylate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for recovering (meth) acrylic acid ester from (meth) acrylic acid ester containing a lower alcohol.

  In general, the production method of (meth) acrylic acid ester includes transesterification reaction of (meth) acrylic acid ester and alcohol, dehydration esterification reaction of (meth) acrylic acid and alcohol, and (meth) acrylic acid to epoxy compound. An addition reaction etc. are mentioned (refer patent document 1). Among them, the production method by transesterification is a method in which the alkoxyl group of an ester such as methyl (meth) acrylate is exchanged with the alkoxyl group of another alcohol in the presence of a catalyst. This is useful in that it is unnecessary.

In the production of (meth) acrylic acid ester by the transesterification method, a lower alcohol such as methanol is produced as a by-product during the transesterification reaction. Since this reaction is an equilibrium reaction, it is necessary to remove these by-products from the reaction system in order to proceed with the reaction. The (meth) acrylic acid ester solution containing the lower alcohol produced by the synthesis by the transesterification method is separated into the aqueous layer by adding water, and the lower alcohol remaining in the extraction and the (meth) acrylic of the oil layer The (meth) acrylic acid ester is recovered by distilling and separating the acid ester. Patent Document 2 describes a salt water extraction method in which salt water is added instead of water to improve the recovery rate of lower alcohol.
JP 2001-48831 A JP-A-9-316034

  As described above, from the (meth) acrylic acid ester solution containing the lower alcohol produced by the transesterification method, water or salt water is added to remove the by-product lower alcohol from the aqueous layer and the oil layer. The (meth) acrylic acid ester is recovered, and a large amount of waste liquid such as water containing a lower alcohol is generated. Further, when the (meth) acrylic acid ester is recovered from the oil layer by distillation, Since (meth) acrylic acid ester azeotropes, the loss of (meth) acrylic acid ester is large and the recovery efficiency is poor. Then, an object of this invention is to isolate | separate a lower alcohol from the (meth) acrylic acid ester solution containing a lower alcohol, and to provide the method of collect | recovering (meth) acrylic acid ester efficiently.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors, as an extraction method for separating a lower alcohol from a (meth) acrylic acid ester, include an azeotropic solvent of a lower alcohol that is hardly soluble in water and water. Can improve the separation efficiency between the oil layer and the water layer, and when the (meth) acrylic acid ester is recovered from the oil layer by distillation, an azeotrope of a lower alcohol and a lower alcohol azeotropic solvent, It was found that the recovery rate of (meth) acrylic acid ester can be improved by sequentially recovering acrylic acid ester. Further, a lower alcohol azeotropic solvent is added to the (meth) acrylic acid ester solution containing the lower alcohol and distilled, and the lower alcohol is obtained by distilling the azeotrope of the lower alcohol and the lower alcohol azeotropic solvent into the aqueous layer. It was found that the recovery rate of (meth) acrylic acid ester can also be improved by extracting and removing to the aqueous layer, and then recovering the lower alcohol azeotrope solvent and (meth) acrylic acid ester in order, and the present invention was completed. It was.

That is, the present invention is described below.
[1] A method for recovering a (meth) acrylic acid ester from a (meth) acrylic acid ester solution containing a lower alcohol using water and a lower alcohol azeotropic solvent, the (meth) acrylic acid ester solution containing the lower alcohol In addition, at least a lower alcohol azeotropic solvent is added, distillation is performed, the lower alcohol is separated into an aqueous layer, and the lower alcohol azeotropic solvent is separated into an oil layer to recover (meth) acrylic acid ester. A method for recovering a (meth) acrylic acid ester.
[2] A method for recovering a (meth) acrylic acid ester from a (meth) acrylic acid ester solution containing a lower alcohol using water and a lower alcohol azeotropic solvent, the (meth) acrylic acid ester containing the lower alcohol Water and a lower alcohol azeotropic solvent are added to the solution and mixed, and then separated into an aqueous layer and an oil layer, and the oil layer is distilled to obtain an azeotrope of the lower alcohol and the lower alcohol azeotropic solvent (meta ) A method for recovering a (meth) acrylic ester, wherein the acrylic ester is recovered in order.
[3] A method for recovering a (meth) acrylic acid ester from a (meth) acrylic acid ester solution containing a lower alcohol using water and a lower alcohol azeotropic solvent, the (meth) acrylic acid ester containing a lower alcohol The lower alcohol azeotropic solvent is added to the solution and distilled, and the lower alcohol and lower alcohol azeotropic solvent distilled are recovered in the aqueous layer to extract and remove the lower alcohol into the aqueous layer. An azeotropic solvent and a (meth) acrylic acid ester are collected in order, and a method for recovering a (meth) acrylic acid ester.
[4] Use of a lower alcohol azeotropic solvent in which the boiling point of the azeotrope of the lower alcohol and the lower alcohol azeotrope is lower than the boiling point of the azeotrope of the lower alcohol and (meth) acrylic acid ester. The method for recovering a (meth) acrylic acid ester according to any one of [1] to [3] above.
[5] The (meth) acrylic acid ester according to any one of the above [1] to [4], wherein the lower alcohol azeotropic solvent is at least one selected from n-pentane, n-heptane, cyclohexane and n-hexane. Recovery method.
[6] The method for recovering a (meth) acrylic acid ester according to any one of the above [1] to [5], wherein the (meth) acrylic acid ester is ethyl acrylate and the lower alcohol is ethanol.
[7] The method for recovering a (meth) acrylic acid ester according to any one of the above [1] to [5], wherein the (meth) acrylic acid ester is methyl methacrylate and the lower alcohol is methanol.
[8] The method for recovering a (meth) acrylic acid ester according to the above [6] or [7], wherein the lower alcohol azeotropic solvent is n-hexane.

  According to the present invention, as an extraction method for separating lower alcohol from (meth) acrylic acid ester, separation of an oil layer and an aqueous layer is performed by adding an azeotropic solvent of lower alcohol which is hardly soluble in water and water. Efficiency can be improved, and the amount of water and waste liquid required for extraction can be reduced. Also, when recovering (meth) acrylic acid ester from the oil layer, recovery of (meth) acrylic acid ester by recovering azeotrope of lower alcohol and lower alcohol azeotropic solvent, (meth) acrylic acid ester in order The rate can be improved.

  Further, a lower alcohol azeotropic solvent is added to the (meth) acrylic acid ester solution containing the lower alcohol and distilled, and the lower alcohol is obtained by distilling the azeotrope of the lower alcohol and the lower alcohol azeotropic solvent into the aqueous layer. The recovery rate of the (meth) acrylic acid ester can also be improved by extracting and removing it into the aqueous layer and then recovering the lower alcohol azeotropic solvent and the (meth) acrylic acid ester in order.

  Examples of the (meth) acrylate used in the present invention include methyl acrylate, ethyl acrylate, butyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate. . In addition, examples of the lower alcohol that is subjected to a transesterification reaction between a raw material (meth) acrylic acid ester and a raw material alcohol in the presence of a catalyst and removed out of the system during the reaction include methanol, ethanol, butanol and the like.

  As the lower alcohol azeotrope used in the present invention, the boiling point of the azeotrope of the lower alcohol and the lower alcohol azeotrope is lower than the boiling point of the azeotrope of the lower alcohol and the (meth) acrylic ester. For example, n-pentane, n-hexane, n-heptane, cyclohexane and the like can be mentioned. When the (meth) acrylate is methyl (meth) acrylate or ethyl (meth) acrylate, N-hexane is preferable from the viewpoint of the boiling point of the boiling material, the solubility in water, and the like.

  As an example of the embodiment of the present invention, a recovery method when the equipment shown in FIG. 1 is used will be described. A jacket 2 is attached to the outer surface of the reactor 1 in FIG. 1, and the liquid in the reactor 1 can be heated.

  The reactor 1 is charged with a (meth) acrylic acid ester solution containing a lower alcohol produced during production of the recovered raw material (meth) acrylic acid ester, and then charged with water to extract and separate the lower alcohol, followed by extraction. In order to improve the oil-water separability, a lower alcohol azeotropic solvent is added. Here, the amount of water or lower alcohol azeotropic solvent added to recover the (meth) acrylate solution is from the viewpoint of the recovery efficiency of (meth) acrylate ester in the (meth) acrylate solution. Water is preferably used in an amount of 25 to 300% by weight and lower alcohol azeotropic solvent in an amount of 30 to 200% by weight, more preferably 100 to 125% by weight and 60 to 90% by weight, respectively. The amount of lower alcohol in the (meth) acrylic acid ester solution can be measured using a gas chromatograph. After these preparations are completed, the mixture is stirred with a stirrer installed in the reactor 1 for 5 minutes or more, and then allowed to stand for 5 to 60 minutes, preferably 10 to 20 minutes, thereby separating into an aqueous layer and an oil layer. To do.

  After separation into the aqueous layer and the oil layer is completed, the aqueous layer is extracted using the line 3 at the bottom of the reactor 1. In addition, visually determining an oil-water interface becomes easy by installing a sight glass in an extraction port.

  Next, the oil layer remaining in the reactor 1 is distilled while heating while controlling the pressure so that the liquid temperature becomes 60 to 100 ° C. The distillate rises while being rectified in the rectification column 4 installed at the upper part of the reactor 1, and is condensed in the condenser 5 at the upper part of the rectification column. As a condensate, an azeotrope of a lower alcohol and a lower alcohol azeotropic solvent and a (meth) acrylic acid ester are recovered in this order. Then, it is recovered using line 7 while refluxing to rectification column 4. When the recovery of the azeotrope of the lower alcohol and the lower alcohol azeotropic solvent is completed, the (meth) acrylic acid ester is subsequently recovered using the line 7. The recovered azeotrope of the lower alcohol and the lower alcohol azeotropic solvent is reused by charging the next recovery operation, preferably by previously extracting and removing the lower alcohol into the aqueous layer. it can. As described above, the reflux line 6 can be used to prepare the azeotrope of the lower alcohol and the lower alcohol azeotropic solvent. It is also possible to charge separately after collecting using the line 7.

  Next, as an example of the embodiment of the present invention, a collection method when the equipment shown in FIG. 2 is used will be described. A jacket 12 is attached to the outer surface of the reactor 11 in FIG. 2 so that the liquid in the reactor 11 can be heated. The reactor 11 is provided with a rectification column 13, and the gas rising in the column is condensed by a condenser 14 at the upper part of the rectification column. The condensate is recovered in the separation tank 17 using the line 16 while refluxing using the line 15. The liquid distilled off in the separation tank 17 can be extracted from the lower layer (water layer) side using the line 18 and the upper layer (oil layer) side can be refluxed to the reactor 11 using the line 19. Unlike the apparatus shown in FIG. 1, the oil layer and the aqueous layer are separated in the separation tank 17 while distillation, so that the aqueous layer is extracted not in the reactor 11 but in the separation tank 17. .

  In the recovery of the (meth) acrylic acid ester solution containing the lower alcohol, the reactor 11 was charged with the (meth) acrylic acid ester solution containing the lower alcohol produced during the production of the (meth) acrylic acid ester, and the separation tank 17 was subjected to the previous work. When the lower alcohol azeotropic solvent distilled in step 1 is contained, the lower alcohol azeotropic solvent is moved to the reactor 1 using the line 19, and otherwise, the lower alcohol azeotropic solvent is newly added to the reactor 11. . Next, water is charged into the empty separation tank 17. Here, the amount of water and lower alcohol azeotropic solvent added to recover the (meth) acrylic acid ester solution is from the viewpoint of the recovery efficiency of the (meth) acrylic acid ester, in the (meth) acrylic acid ester solution. It is preferable to use 10 to 300% by weight of water and 30 to 200% by weight of the lower alcohol azeotropic solvent with respect to the lower alcohol, and more preferably 30 to 50% by weight and 80 to 100% by weight, respectively.

  After completion of the water charging to the separation tank 17, the reactor 11 is heated and distilled while controlling the pressure so that the liquid temperature becomes 60 to 100 ° C. First, since the azeotrope of the lower alcohol and the lower alcohol azeotropic solvent is distilled, it is recovered in the separation tank 17. Since water is charged in the separation tank 17 in advance, the lower alcohol in the distillate is extracted to the water layer side, and the lower alcohol azeotropic solvent that is hardly soluble in water becomes an oil layer.

  When the azeotrope of the lower alcohol and the lower alcohol azeotrope continues to distill, the lower alcohol azeotrope that has become the oil layer in the separation tank 17 is returned to the reactor 11 by overflowing from the line 19. This operation can be repeated until the lower alcohol in 11 disappears. In addition, since the lower alcohol in the reactor 11 runs out when the distillation of the lower alcohol is completed, it can be determined by a change in the liquid temperature in the reactor 11.

  When the lower alcohol in the reactor 11 runs out, the distillation is stopped once, and the lower alcohol aqueous solution in the separation tank 17 is drawn out of the system. When the separation tank 17 becomes empty, distillation is resumed, and the lower alcohol azeotropic solvent in the reactor 11 is distilled into the separation tank 17. When the distillation of the lower alcohol azeotropic solvent is completed and the lower alcohol azeotropic solvent in the reactor 11 is exhausted, the distillation is stopped and the (meth) acrylic acid ester is recovered from the bottom of the reactor 11 using the line 20. . The point in time when the lower alcohol azeotropic solvent in the reactor 11 runs out can be determined by the change in the liquid temperature in the reactor 11.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to an Example.
Example 1
Recovery of ethyl acrylate Using the apparatus shown in FIG. 1, 3212 kg of an ethyl acrylate solution containing 38% by weight of ethanol was charged into the reactor 1, and then 1500 kg of water and 780 kg of n-hexane were charged into the reactor 1. After stirring for 10 minutes with the stirrer which was installed, it was left still for 15 minutes and isolate | separated into the oil layer and the water layer. Thereafter, 2565 kg of the aqueous layer was extracted from the lower side of the reactor 1 via the line 3. The ethanol removal rate {(ethanol charge amount−ethanol amount in oil layer) / ethanol charge amount} at this time was 75.7% by weight. The amount of ethanol in the oil layer was measured with a gas chromatograph.

Next, 2653 kg of an ethyl acrylate solution having a low ethanol content of 5% by weight was additionally charged, and distillation was started. The distillation was performed by heating while controlling the pressure so that the liquid temperature was 80 ° C. As a distillation distillate, first, an azeotrope of ethanol and n-hexane, followed by ethanol, n-hexane, and ethyl acrylate azeotrope in the order of 14 wt% ethanol and acrylic acid 1420 kg of n-hexane solution containing 20% by weight of ethyl was recovered, followed by recovery of 2663 kg of ethyl acrylate. The recovered n-hexane solution containing ethanol and ethyl acrylate was reused in the next recovery operation. The recovery rate of ethyl acrylate in this recovery was 77.3%. The recovery rate was obtained by calculation as follows.
Ethyl acrylate recovery amount 2663 kg ÷ ethyl acrylate total charge 3443 kg × 100 = 77.3% (The amount of ethyl acrylate remaining in the apparatus is not included in the recovery amount)

(Comparative Example 1)
Extraction of ethanol from ethyl acrylate solution using only water The same operation as in Example 1 was performed except that the distillation operation was not performed. The ethanol removal rate with respect to ethanol in the ethyl acrylate solution was 32%, which was significantly lower than 75.7% by weight of Example 1. Therefore, in order to extract ethanol to the same extent as in Example 1, a larger amount of water is required.

(Example 2)
Recovery of methyl (meth) acrylate Using the apparatus shown in FIG. 2, 900 kg of methyl methacrylate solution containing 60% by weight of methanol was charged into the reactor 11, and methanol and n recovered in the previous recovery operation from the separation tank 17. -630 kg of n-hexane solution containing 7% by weight of methanol which is an azeotrope of hexane and methyl methacrylate and 9% by weight of methyl (meth) acrylate was returned to the reactor 11 via the line 19. Thereafter, 200 kg of water was charged into the empty separation tank 17.

Distillation is started by heating while controlling the pressure so that the liquid temperature of the reactor 11 becomes 80 ° C., and an azeotrope of methanol and n-hexane is distilled into a separation tank through a rectifying column. When a change in the liquid temperature was observed, the distillation was temporarily stopped, and 762 kg of an aqueous layer containing 71 wt% of methanol was extracted from the bottom of the separation tank 17 via the line 18. Next, when the separation tank 17 is emptied, the distillation is restarted by heating while controlling the pressure so that the liquid temperature of the reactor 11 becomes 80 ° C., and n-hexane in the reactor 11 is transferred to the separation tank 17. Distillation was completed, and distillation was terminated when a change in the temperature of the reactor 11 was observed, and 348 kg of methyl (meth) acrylate was recovered from the bottom of the reactor 11 via the line 20. The recovery rate of methyl (meth) acrylate in this recovery was 83.5%. The recovery rate was obtained by calculation as follows.
(Meth) methyl acrylate recovery amount 348 kg ÷ (meth) methyl acrylate total charge 417 kg × 100 = 83.5% (the amount of methyl (meth) acrylate remaining in the apparatus is not included in the recovery amount)

  According to the present invention, as an extraction method for separating lower alcohol from (meth) acrylic acid ester, separation of an oil layer and an aqueous layer is performed by adding an azeotropic solvent of lower alcohol which is hardly soluble in water and water. Efficiency can be improved, and the amount of water and waste liquid required for extraction can be reduced. Also, when recovering (meth) acrylic acid ester from the oil layer, recovery of (meth) acrylic acid ester by recovering azeotrope of lower alcohol and lower alcohol azeotropic solvent, (meth) acrylic acid ester in order The rate can be improved.

It is the equipment schematic used by crude ethyl acrylate collection | recovery. It is the equipment schematic used by crude methyl methacrylate recovery.

Explanation of symbols

1: Reactor 2: Jacket 4: Rectification tower 5: Capacitors 3, 6, 7: Piping (line)
11: Reactor 12: Jacket 13: Rectification tower 14: Condenser 17: Separation tanks 15, 16, 18, 19, 20: Piping (line)

Claims (8)

  A method for recovering a (meth) acrylic acid ester from a (meth) acrylic acid ester solution containing a lower alcohol using water and a lower alcohol azeotropic solvent, the (meth) acrylic acid ester solution containing a lower alcohol, The distillation is performed by adding at least a lower alcohol azeotropic solvent, separating the lower alcohol into an aqueous layer, and separating the lower alcohol azeotropic solvent into an oil layer, thereby recovering a (meth) acrylic ester. (Meth) acrylic acid ester recovery method.   A method for recovering a (meth) acrylic acid ester from a (meth) acrylic acid ester solution containing a lower alcohol using water and a lower alcohol azeotropic solvent, the (meth) acrylic acid ester solution containing a lower alcohol, Water and a lower alcohol azeotropic solvent are added and mixed, and then separated into an aqueous layer and an oil layer, and the oil layer is distilled to obtain an azeotrope of the lower alcohol and the lower alcohol azeotropic solvent, (meth) acrylic A method for recovering a (meth) acrylic acid ester, wherein the acid ester is recovered in order.   A method for recovering a (meth) acrylic acid ester from a (meth) acrylic acid ester solution containing a lower alcohol using water and a lower alcohol azeotropic solvent, the (meth) acrylic acid ester solution containing a lower alcohol, The lower alcohol azeotropic solvent is added and distilled, and the lower alcohol and the lower alcohol azeotropic solvent are recovered in the aqueous layer to extract and remove the lower alcohol to the aqueous layer. And (meth) acrylic acid ester are collected in order.   It is characterized by using a lower alcohol azeotropic solvent in which the boiling point of the azeotrope of the lower alcohol and the lower alcohol azeotrope is lower than the boiling point of the azeotrope of the lower alcohol and (meth) acrylic acid ester. The method for recovering a (meth) acrylic acid ester according to claim 1.   The method for recovering a (meth) acrylic acid ester according to any one of claims 1 to 4, wherein the lower alcohol azeotropic solvent is one or more selected from n-pentane, n-heptane, cyclohexane and n-hexane.   The method for recovering a (meth) acrylic acid ester according to any one of claims 1 to 5, wherein the (meth) acrylic acid ester is ethyl acrylate and the lower alcohol is ethanol.   The method for recovering a (meth) acrylic acid ester according to any one of claims 1 to 5, wherein the (meth) acrylic acid ester is methyl methacrylate and the lower alcohol is methanol.   The method for recovering a (meth) acrylic acid ester according to claim 6 or 7, wherein the lower alcohol azeotropic solvent is n-hexane.

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