KR102019037B1 - Method of preparing alkyl carboxylic acid ester - Google Patents

Abstract

In the process for preparing alkyl carboxylic acid esters according to embodiments of the present invention, the carboxylic acid stream and the first alcohol stream are reacted in a preliminary reactor. The first reactant produced from the preliminary reactor is esterified by reaction with a second alcohol stream in the main reactor. The alkyl carboxylic ester is recovered from the main reactor.

Description

METHODS OF PREPARING ALKYL CARBOXYLIC ACID ESTER

The present invention relates to a process for the preparation of alkyl carboxylic esters. More particularly, the present invention relates to a process for preparing alkyl carboxylic esters through esterification of alcohols and carboxylic acids.

For example, alkyl carboxylic acid esters such as ethyl lactate are widely used as solvents for various polishing liquids, etching liquids, photosensitive resin compositions, resist compositions and the like used in semiconductor manufacturing processes and display manufacturing processes.

In the case of a semiconductor manufacturing process requiring precision of several tens or several nanoscales, each component of the composition is also required to have high purity, and when a small amount of impurities are included, reliability of the entire semiconductor manufacturing process may be reduced. Therefore, there is a need for securing high-purity ethyl lactate used in precision processes.

Ethyl lactate can be obtained, for example, via esterification of lactic acid and ethanol. Lactic acid can be synthesized bio-based through fermentation reactions using microorganisms.

In this case, the lactic acid raw material may contain impurities derived from microorganisms, fermentation raw materials, and the like, thereby lowering the purity and selectivity of ethyl lactate. In addition, the purity and selectivity of ethyl lactate may be lowered by impurities through the self reaction of lactic acid.

Therefore, for the high purity, high selectivity ethyl lactate synthesis process, the reactor also needs to be designed to have a high selectivity and high capacity for the esterification reaction, high purity ethanol needs to be used. In this case, the load of the reactor is excessively increased and high costs may be required.

For example, Korean Patent Laid-Open Publication No. 2005-0084179 discloses a process for producing continuous ethyl lactate, but as described above, it is necessary to study an esterification process design that removes impurities from lactic acid and improves economic efficiency. There is.

Korean Laid-Open Patent Publication No. 2005-0084179 (August 26, 2005)

One object of the present invention is to provide a method for producing an alkyl carboxylic ester having excellent purity and selectivity.

One object of the present invention is to provide an alkyl carboxylic ester production apparatus having excellent purity and selectivity.

1. reacting the carboxylic acid stream and the first alcohol stream in a pre-reactor; Reacting the first reactant produced from the preliminary reactor with a second alcohol stream in a main reactor to esterify it; And recovering alkyl carboxylic acid esters from the main reactor.

2. The alkyl according to 1 above, wherein the carboxylic acid stream comprises lactic acid, the first alcohol stream and the second alcohol stream comprise ethanol, and the alkyl carboxylic acid ester comprises ethyl lactate. Process for the preparation of carboxylic esters.

3. The method of 1 above, wherein the preliminary reactor comprises a catalyst supported guard reactor, the method of producing an alkyl carboxylic ester.

4. The method of 1 above, wherein the reacting in the preliminary reactor comprises converting a portion of the carboxylic acid stream to an ester.

5. The method according to the above 4, wherein the ester conversion in the pre-reactor is 50 to 80%, the preparation method of the alkyl carboxylic acid ester.

6. The method of 4 above, wherein the step of reacting in the pre-reactor further comprises the step of hydrolyzing an aggregate comprising a dimer, trimer or oligomer contained in the carboxylic acid stream, alkyl carboxylic acid ester of Manufacturing method.

7. The method according to the above 1, wherein the main reactor comprises a reactive distillation column, the method of producing an alkyl carboxylic acid ester.

8. The process of 1 above, wherein the first alcohol stream has a lower purity than the second alcohol stream.

9. The method of 1 above, further comprising refluxing the alcohol from the main reactor, a method for producing an alkyl carboxylic ester.

10. The method of 9 above, wherein the refluxed alcohol from the main reactor is combined with the first alcohol stream.

11. preliminary reactor for partial esterification of carboxylic acids via reaction with alcohols; A main reactor for receiving a reactant from the preliminary reactor to esterify unreacted carboxylic acid; And a separation purification unit for collecting the alkyl carboxylic acid esters produced from the main reactor.

12. The method of 11 above, wherein the carboxylic acid supply passage and the first alcohol supply passage connected to the pre-reactor; And a second alcohol supply flow path connected with the main reactor.

13. The apparatus according to the above 11, wherein the separation purification unit comprises a vacuum distillation column to obtain an alkyl carboxylic acid ester in the reactants from the main reactor.

14. The apparatus according to 11 above, further comprising a reflux unit for recovering alcohol from the main reactor to the preliminary reactor.

15. The apparatus according to 11 above, wherein the carboxylic acid and the alcohol include lactic acid and ethanol, respectively, and an alkyl carboxylic acid ester for ethyl lactate production.

According to the method for preparing alkyl carboxylic acid esters according to embodiments of the present invention, a preliminary reactor or a partial conversion of alcohol and carboxylic acid may be prepared by, for example, arranging a preliminary reactor in front of a main reactor including a reactive distillation reactor. Can be done. Therefore, it is possible to prevent the decrease in selectivity due to overload in the main reactor, and to improve the efficiency of the post-stage process.

In addition, the purity and selectivity of the ester product are improved by decomposing aggregates such as dimers, trimers and oligomers generated from carboxylic acids through hydrolysis in the preliminary reactor and removing impurities in advance. You can.

In addition, as the partial conversion is performed in the preliminary reactor, it is possible to lower the purity of the alcohol used relatively, and further improve the economics of the process.

1 is a flowchart illustrating an apparatus and a manufacturing method of an alkyl carboxylic acid ester according to an exemplary embodiment of the present invention.
2 is a cross-sectional view showing a schematic structure and operation of a pre-reactor used in accordance with embodiments.
3 is a cross-sectional view showing the schematic structure and operation of the main reactor used in accordance with the embodiments.

Hereinafter, preferred embodiments of the present invention are described, but these embodiments are merely illustrative of the present invention, and are not intended to limit the appended claims, and various embodiments of the present invention are within the scope and spirit of the present invention. Modifications and variations are apparent to those skilled in the art, and such variations and modifications are naturally within the scope of the appended claims.

As used herein, the term "alkyl carboxylic ester" refers to the esterification reaction product of carboxylic acid and alkyl alcohol. According to exemplary embodiments of the present invention, lactic acid may be used as the carboxylic acid, and ethanol may be used as the alkyl alcohol. In this case, ethyl lactate may be obtained as the alkyl carboxylic acid ester.

However, the scope of the present invention is not necessarily limited to the method and apparatus for preparing ethyl lactate, but may be extended to methods and apparatus for esterification of various carboxylic acids and alkyl alcohols.

1 is a flowchart illustrating an apparatus and a manufacturing method of an alkyl carboxylic acid ester according to an exemplary embodiment of the present invention. In FIG. 1, an apparatus and a manufacturing method of ethyl lactate, in which lactic acid is used as a carboxylic acid and ethanol is used as an alkyl alcohol, are exemplarily illustrated.

Referring to FIG. 1, an apparatus for preparing alkyl carboxylic acid esters according to exemplary embodiments may include a preliminary reactor 100, a main reactor 200, and a reflux unit 300.

The preliminary reactor 100 may be connected to the carboxylic acid supply flow path 70 and the first alcohol supply flow path 90. The lactic acid stream may be fed into the preliminary reactor 100 via the carboxylic acid feed passage 70 (eg, step S11). The first ethanol stream may be fed into the preliminary reactor 100 through the first alcohol feed passage 90 (eg step S13). The lactic acid stream feed and the first ethanol stream feed may be performed simultaneously or sequentially.

The first ethanol stream may be of lower purity than the second ethanol stream described below. In some embodiments, the purity of the first ethanol stream may be about 80-97%. In one embodiment, the purity of the first ethanol stream may be about 80-95%. In one embodiment, the purity of the first ethanol stream may be about 80-90%.

As used herein, the term “purity” may refer to the weight percent of the subject material to the total weight. For example, 80% pure ethanol may refer to a mixture of 20% water and 80% ethanol by weight.

Lactic acid may be a fermentation product using microorganisms. For example, starch, sugar, cellulose, algae, and other organic products may be glycosylated and the glycated products may be obtained by fermentation through microorganisms capable of lactic acid fermentation.

Accordingly, the lactic acid stream fed to the preliminary reactor 100 may include various bio by-products such as the microorganisms, proteins, cells, minerals, and the like.

According to example embodiments, the preliminary reactor 100 may include a guard reactor. The guard reactor may comprise, for example, a catalyst supported bed, such as a solid acid catalyst, and in one embodiment may comprise a single bed.

In the preliminary reactor 100, a pre-esterification reaction of the lactic acid included in the first ethanol stream and the lactic acid stream may be performed (for example, step S20). In some embodiments, the temperature of the pre-esterification reaction may be about 70 to 110 ° C, preferably about 80 to 100 ° C.

In the preliminary reactor 100, part of the lactic acid can be partially converted to ethyl lactate by the preesterification. According to exemplary embodiments, the partial conversion rate in the preliminary reactor 100 may be about 50 to 80%.

When the partial conversion rate in the preliminary reactor 100 is less than about 50%, the reaction load in the main reactor 200 to be described later is excessively high, and it may be difficult to obtain ethyl lactate having a desired selectivity and purity. If the partial conversion exceeds about 80%, the esterification in the preliminary reactor 100 may rise too much to reduce the overall process efficiency.

In some embodiments, hydrolysis may proceed together in the preliminary reactor 100. The hydrolysis may proceed through water contained in the first ethanol stream and the lactic acid stream, and in one embodiment, a water channel for supplying water into the preliminary reactor 100 may be disposed separately.

According to exemplary embodiments, lactic acid aggregates can be degraded through hydrolysis. The lactic acid aggregates may include dimers, trimers or oligomers of lactic acid molecules. When the lactic acid aggregate is contained in a large amount in the lactic acid stream, it is possible to reduce the selection ratio of ethyl lactate, and the overall process efficiency may be reduced by increasing the load in the main reactor 200 or a post process.

In one embodiment, the pre-reactor 100 may be injected or supported with a catalyst for promoting hydrolysis. For example, sulfuric acid, silica, zeolite, hydroxide of alkali metal or alkaline earth metal, etc. are mentioned as an example of the said catalyst.

According to an exemplary embodiment of the present invention, the hydrolysis of the lactic acid aggregates is carried out together with the preliminary esterification or partial conversion in the preliminary reactor 100, so that the selection in the main reactor 200 or the post process is performed. The ratio can be raised and the post process scale reduced.

After partial conversion from the preliminary reactor 100, a stream (eg, first reactant) may be fed to the main reactor 200 through the first reactant flow path 110. The stream after the partial conversion may comprise ethyl lactate partially converted in the preliminary reactor 100, unreacted lactic acid in the lactic acid stream, unreacted ethanol in the first ethanol stream, and excess water.

According to example embodiments, the main reactor 200 may comprise a single reactive distillation column. As partial esterification is performed in the preliminary reactor 100, the number of columns, or process load, of the main reactor 200 can be reduced. In some embodiments, main reactor 200 may include a plurality of reactive distillation columns connected in series or in parallel.

The reactive distillation column may be filled with a catalyst supported medium, for example a solid acid catalyst. For example, an ion exchange resin containing sulfonic acid groups can be filled in the reactive distillation column. The ion exchange resin may include, for example, polysiloxane, polystyrene, polydivinylbenzene, or the like. The ion exchange resin may also be surface treated with a metal such as zirconium or titanium, or an oxide thereof.

In the main reactor 200, after the partial conversion, unreacted lactic acid contained in the stream may be converted to ethyl lactate through reaction with ethanol (for example, step S40). In some embodiments, the temperature of the esterification reaction in main reactor 200 may be about 70 to 110 ° C, preferably 80 to 100 ° C.

In some embodiments, a second ethanol stream may be fed into the main reactor 200 (eg, step S30). For example, the second ethanol stream may be fed through a second alcohol feed passage 130 that is separately connected to the main reactor 200.

The second ethanol stream may have a higher purity than the first ethanol stream introduced into the preliminary reactor 100. In exemplary embodiments, the purity of the second ethanol stream may have a purity of at least about 95%, preferably at least about 99%.

By increasing the purity of ethanol introduced directly into the main reactor 200, it is possible to improve the selectivity of the ethyl lactate obtained. As noted above, according to exemplary embodiments, a relatively low purity first ethanol stream may be used to partially convert the lactic acid in the preliminary reactor 100. Therefore, it is possible to reduce the amount of high-purity high-purity ethanol while maintaining the desired selection ratio, and to improve the economics and efficiency of the entire process.

For example, a product after the main reaction may be introduced into a post process (for example, S50 step) through the second reactant flow path 210 at the bottom of the main reactor 200. In the upper portion of the main reactor 200, ethanol evaporated through the reactive distillation column may be collected and supplied to the reflux unit 300 through the alcohol collection passage 220. Ethanol reflux (eg, step S60) may be performed from the reflux unit 300 to generate a reflux stream through the first reflux flow path 310.

According to exemplary embodiments, the reflux stream may be combined with the first ethanol stream and fed to the preliminary reactor 100. The ethanol purity of the reflux stream may be substantially the same as the purity of the first ethanol stream.

Reflux unit 300 may include, for example, a single distillation column or a single distillation drum. As the purity of the first ethanol stream fed to the initial reactants is relatively low, the concentration or distillation process load performed on the reflux unit 300 may also be reduced. Thus, the scale or structure of the reflux unit 300 can be simplified.

As described above, by performing a partial esterification by supplying relatively low purity ethanol to the preliminary reactor 100 through a reflux unit, and supplying high purity ethanol separately to the main reactor 200, Can increase economics and efficiency.

Post-processing (eg, S50) may comprise a process of concentrating and / or collecting the target ester. According to exemplary embodiments, the apparatus for preparing alkyl carboxylic acid ester may be disposed after the main reactor 200 and may include a separate purification unit 400 for collecting the target ester.

In some embodiments, the separation purification unit 400 may include a distillation unit (eg, a vacuum distillation column). As described above, after the reaction, a product (eg, the second reactant) may be supplied to the distillation unit from the second reactant flow path 210 connected to the bottom of the main reactor 200.

The product after the reaction may comprise ethyl lactate, residual ethanol and byproducts produced from the main reactor 200. For example, the by-products may include aggregates such as dimers, trimers or oligomers, bio-derived residues and the like produced from lactic acid. As described above, since the by-products can be at least partially decomposed through hydrolysis in the preliminary reactor 100, the amount of by-products in the product after the reaction can be significantly reduced.

Ethyl lactate having a low boiling point in the product after the reaction may be taken out from the top of the vacuum distillation column to obtain a target ester. The by-products having a high boiling point in the product after the reaction may be removed from the bottom of the vacuum distillation column and removed.

As described with reference to FIG. 1, as aggregates of dimers, trimers, oligomers, and the like of lactic acid are preliminarily decomposed or removed through hydrolysis in the preliminary reactor 100, the load of a post process may be reduced. have. Thus, further process steps, such as ester hydrolysis and / or Trans Esterification (TE) units, which are carried out further, may be removed or scaled down to increase process efficiency.

Accordingly, the load, scale, and time of the post process may be reduced to improve overall process efficiency, and the selectivity and purity of the target ester (eg, ethyl lactate) may be increased.

Hereinafter, with reference to specific experimental examples, it will be described in detail a method for producing an alkyl carboxylic acid ester according to the embodiments of the present invention. The Examples and Comparative Examples included in the Experimental Examples are only illustrative of the present invention and do not limit the appended claims, and various changes and modifications to the Examples are possible within the scope and spirit of the present invention. It is obvious to those skilled in the art, and it is natural that such variations and modifications fall within the scope of the appended claims.

Experimental Example

1) Ethyl lactate conversion in preliminary reactor

Example 1

88 wt% lactic acid (LA) and 80 wt% ethanol (EtOH) were mixed and used as feed to the prereactor. The molar ratio of lactic acid and ethanol was adjusted to 1: 1. Lactic acid used bio-derived products produced from the fermentation process.

As shown in FIG. 2, the esterification reaction was performed under atmospheric pressure at a temperature of about 80 ° C. in a single bed type pre-reactor filled with a solid acid catalyst. The ethyl lactate (EL) containing product was cooled by a cooling device through a prereactor and the liquid composition was measured by an Agilent 7890 restek RTx-VRX GC Column for flame ionization detectors (FIDs).

Example 2

The esterification reaction was carried out in the same manner as in Example 1 except that the molar ratio of lactic acid and ethanol was adjusted to 1: 2, and the liquid composition was measured.

Example 3

The esterification reaction was carried out in the same manner as in Example 1, except that 88% by weight of lactic acid and 90% by weight of ethanol were used as a feed of the prereactor (molar ratio of lactic acid and ethanol was 1: 1). And the liquid composition was measured.

Example 4

Except for adjusting the molar ratio of lactic acid and ethanol 1: 2, the esterification reaction was carried out in the same manner as in Example 3, and the liquid composition was measured.

Conversion, yield and selectivity of ethyl lactate (EL) measured through Examples 1 to 4 are as shown in Table 1 below.

Ratio Example  One Example  2 Example  3 Example 4 Conversion (%) 55.0 76.9 71.9 76.8 EL yield (%) 50.9 68.6 63.5 70.9 EL Selectivity (%) 92.5 90.1 80.3 90.2

Referring to Table 1, ester conversions of about 50-80% were obtained through the preliminary reactor in Examples 1-4.

2) ethyl lactate conversion in the main reactor

Example 5

A reactive distillation (RD) column packed with a solid acid catalyst was used as the main reactor (see FIG. 3). In addition, the reactants produced through the preliminary reactor used in Example 1 were used as feed to the main reactor.

The feed was fed to the upper part of the main reactor, 99% ethanol was introduced into the lower part of the main reactor, respectively, and the esterification reaction was completed at a temperature of about 80 ° C. and atmospheric pressure. The volume ratio of the feed and the injected ethanol was adjusted to 1: 0.5.

The product obtained from the bottom of the main reactor column (stripping section, see Figure 3) is cooled by a cooling apparatus and using an Agilent 7890 restek RTx-VRX GC Column for the flame ionization detectors (FIDs). The liquid composition was measured.

Example 6

The esterification in the main reactor was carried out in the same manner as in Example 5 except that the volume ratio of the feed and the injected ethanol was adjusted to 1: 1, and the composition of the product was measured.

Comparative example

88 wt% lactic acid (manufactured by Galactic) was used as a feed, and 99% ethanol was prepared. The feed was the upper part of the main reactor as in Example 5, 99% ethanol was introduced into the lower part and the esterification reaction was completed at a temperature of about 80 ° C. and atmospheric pressure. The volume ratio of the feed and ethanol was adjusted to 1: 2.

The liquid composition of the obtained product was measured in the same manner as in Example 5.

Conversion, yield and selectivity of ethyl lactate (EL) measured through Examples 5, 6 and Comparative Examples are as shown in Table 2 below.

Ratio Example 5 Example 6 Comparative example Time (h) 2 4 6 2 4 6 2 4 6 Conversion (%) 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 EL yield (%) 91.7 95.8 97.6 98.4 96.9 95.9 90.1 89.0 89.4 EL Selectivity (%) 91.7 95.8 97.6 98.4 96.9 95.9 90.1 89.0 89.4

Referring to Table 2, when the same 100% conversion was achieved, the by-products of Example 5 and Example 6 which passed through the preliminary reactor were reduced compared to the comparative example, which significantly increased the yield, selectivity and purity of the final ethyl lactate.

It can be seen that the load and reaction efficiency in the main reactor were increased as the lactic acid aggregate was hydrolyzed in advance through partial esterification using a guard reactor before the main reaction.

70: carboxylic acid supply flow path 90: first alcohol supply flow path
100: pre-reactor 110: first reactant flow path
130: second alcohol supply flow path 200: main reactor
210: second reactant flow path 220: alcohol collection flow path
300: reflux unit 310: first reflux flow path
400: separation / purification unit

Claims (15)

Reacting the carboxylic acid stream comprising lactic acid and the first alcohol stream in a preliminary reactor comprising a catalyst supported guard reactor;
Reacting the first reactant produced from the preliminary reactor with a second alcohol stream in a main reactor to esterify it; And
Recovering alkyl carboxylic ester from said main reactor,
Reacting in the preliminary reactor comprises hydrolyzing the lactic acid aggregate comprising dimers, trimers or oligomers contained in the carboxylic acid stream through the catalyst supported guard reactor. Method of preparation.
The method of claim 1, wherein the first alcohol stream and the second alcohol stream comprise ethanol and the alkyl carboxylic ester comprises ethyl lactate.
delete The method of claim 1, wherein reacting in the preliminary reactor comprises converting a portion of the carboxylic acid stream to an ester.
The method of claim 4, wherein the ester conversion in the preliminary reactor is 50-80%.
delete The method of claim 1, wherein the main reactor comprises a reactive distillation column.
The method of claim 1, wherein the first alcohol stream has a lower purity than the second alcohol stream.
The method of claim 1, further comprising refluxing alcohol from the main reactor.
10. The method of claim 9, wherein the refluxed alcohol from the main reactor is combined with the first alcohol stream.
A pre-reactor comprising a guard reactor carrying a catalyst for partially esterifying a carboxylic acid comprising lactic acid with an alcohol and hydrolyzing the lactic acid aggregate comprising a dimer, trimer or oligomer;
A main reactor for receiving a reactant from the preliminary reactor to esterify unreacted carboxylic acid; And
An apparatus for producing an alkyl carboxylic ester, comprising a separation purification unit for collecting the alkyl carboxylic ester produced from the main reactor.
The method according to claim 11,
A carboxylic acid feed passage and a first alcohol feed passage connected to the preliminary reactor; And
Apparatus for producing an alkyl carboxylic acid ester further comprising a second alcohol supply flow path connected with the main reactor.
The apparatus of claim 11, wherein the separation purification unit comprises a vacuum distillation column to obtain an alkyl carboxylic ester in the reactants from the main reactor.
The apparatus of claim 11, further comprising a reflux unit for recovering alcohol from the main reactor to the preliminary reactor.
The apparatus of claim 11, wherein the alcohol comprises ethanol and wherein the alkyl carboxylic ester is for ethyl lactate production.

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