KR101349106B1 - Method for preparing glycol ester using reactive distillation - Google Patents

Abstract

The present invention relates to a method for manufacturing glycol ester using glycol ether and carboxylic acid and, more specifically, to a method for manufacturing glycol ester which increases the conversion rate of glycol ether at low temperature and pressure conditions, minimizes reflux amount by using a reactive distillation tower and reduces the product amount of impurities. The present invention reduces the loss of glycol ester to an upper part of the reactive distillation tower by injecting excessive carboxylic acid as compared to the mole number of glycol ether and conveniently separating glycol ester and carboxylic acid under pressurization conditions and simplifies a rear end separation column process without a separate azeotropic distillation apparatus. [Reference numerals] (R-100) First reactor; (V-100) First distillation tower; (V-200) Second distillation tower; (V-300) Third distillation tower; (V-400) Fourth distillation tower

Description

Method for preparing glycol ester using reactive distillation

The present invention relates to a process for the continuous preparation of glycol esters from glycol ethers and carboxylic acids using a catalytic distillation column packed with a catalyst.

Specifically, the present invention relates to a method for continuously preparing high-purity glycol esters for electronics without having an azeotropic distillation unit in the rear by injecting carboxylic acid in an inflow reactant in an excess relative to the number of moles of glycol ether.

In general, glycol esters are solvents such as paints, inks, adhesives, cleaning agents, and the like. Many studies have been conducted on the preparation or purification of glycol esters by reacting glycol ethers with carboxylic acids.

U.S. Patent No. 5,618,973 discloses a process for the addition of glycol ethers and carboxylic acids using benzene sulfonic acid to prepare glycol esters, followed by purification using cyclohexane, an azeotroping solvent. When this method is used, separation of the product and the catalyst is required, and since the use of the co-agent requires purification of the non-co-agent, the process is complicated.

U.S. Patent No. 5,202,463 also discloses a process for purifying the product using Methyl Isobutyl Ketone (MIBK) as an azeotroping solvent.

As such, when benzene sulfonic acid is used as a catalyst, post-treatment such as catalyst separation is complicated, and when the product is purified using a non-conjugating agent, purification of the non-conjugating agent is required, and process operation is not easy, and a glycol ether as a reactant is required. And loss of the carboxylic acid, the glycol ester as the product.

In addition, in order to produce propylene glycol mono methyl ether acetate (PMA) in the glycol ester, propylene glycol mono methyl ether (PM) and acetic acid (AA) are uniformly acidic. Obtained by carrying out esterification reaction under a catalyst. However, since the esterification reaction itself is an equilibrium reaction, there is a limit in the conversion rate that can be obtained under the reaction conditions.

In this case, it is necessary to increase the operating temperature of the reactor and the distillation column in order to increase the reaction conversion rate. In addition, since high temperature corrosiveness of the material exists near the boiling point (Acetic acid: AA) of acetic acid (AA), it is common to lower the AA content by injecting PM in excess.

However, in case of injecting excessive amount of propylene glycol mono methyl ether (PM), in addition to the minimum azeotropy point between propylene glycol mono methyl ether acetate (PMA) / water (Water) There is an additional minimum azeotropy between the converted propylene glycol mono methyl ether (PM) / water to form a distillation boundary and propylene glycol monomethyl ether acetate to the top of the column. Loss of mono methyl ether acetate (PMA) and propylene glycol mono methyl ether (PM) occurs. Therefore, the process of recovering the pure PMA at the back and the unreacted substance is made by utilizing an azeotropic distillation technique for recovering propylene glycol mono methyl ether acetate (PMA) into the distillation column and separating water as a byproduct. There is a problem that the process of separating the water and the complexity.

United States Patent US4544453 United States Patent US5618973

The present invention increases the conversion rate of glycol ether at low temperature and pressure conditions using a reactor and a reaction distillation column, suppresses the occurrence of minimum azeotropic point of glycol ether and water, and separate azeotropic distillation apparatus (Decanter and azeotrope injection / It is an object of the present invention to prepare an electronic glycol ester which simplifies the rear end separation process without a recovery facility.

It is also an object of the present invention to provide a high-purity electronic glycol ester that suppresses the formation of impurities by separating carboxylic acids under pressurization conditions above atmospheric pressure and reducing the amount of glycol ether introduced.

The present invention to achieve the above object, the step of reacting a glycol ether and carboxylic acid using a first reactor and a first distillation column; Calculating an unreacted substance and generated water to an upper portion of the first distillation column, and a glycol ester including an unreacted carboxylic acid and impurities to a lower portion of the first distillation column; Separating unreacted material and product water using a second distillation column and recycling the unreacted material to a first reactor or a first distillation column; And separating the unreacted carboxylic acid calculated at the bottom of the first distillation column using a third distillation column under pressurized conditions, wherein the carboxylic acid introduced into the first reactor is in excess of the number of moles of glycol ether. Injected, the first distillation column may be a method for producing a glycol ester, characterized in that the reaction distillation column.

According to the preparation method of the glycol ester according to the present invention, it is possible to increase the conversion rate of the reactants under low operating temperature and pressure, to dramatically reduce the amount of reflux and to reduce the amount of impurities even under mild reaction conditions.

In the method for preparing a glycol ester according to the present invention, by injecting an excess of carboxylic acid (excess), the azeotropy point of the glycol ether and the produced water does not exist, thereby simplifying the post-stage separation process and operating the column operated under pressurized conditions. By easily separating the carboxylic acid through it can provide a high purity electronic glycol ester.

1 is a schematic diagram of a process for producing a glycol ester according to the present invention.
2 is a schematic diagram of a reaction distillation column packed with a catalyst according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples and drawings, but is only an embodiment limited to the gist of the present invention. On the other hand, the present invention is not limited to the process conditions presented in the following Examples, it will be apparent to those skilled in the art can be arbitrarily selected within the range of conditions necessary to achieve the object of the present invention.

Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

The present invention comprises the steps of reacting a glycol ether and carboxylic acid using a first reactor and a first distillation column; Calculating an unreacted substance and generated water to an upper portion of the first distillation column, and a glycol ester including an unreacted carboxylic acid and impurities to a lower portion of the first distillation column; Separating unreacted material and product water using a second distillation column and recycling the unreacted material to a first reactor or a first distillation column; And separating the unreacted carboxylic acid calculated at the bottom of the first distillation column by using a third distillation column under pressurized conditions, wherein the carboxylic acid introduced into the first reactor is in excess of the number of moles of glycol ether. Injected, the first distillation column may be a method for producing a glycol ester, characterized in that the reaction distillation column.

In the esterification reaction in which the glycol ether and the carboxylic acid meet according to the present invention, it is preferable to equip the reactor with a predetermined reactor before the glycol ether and the carboxylic acid are introduced into the reaction distillation column in order to design a conversion to increase the conversion rate.

The following is an esterification reaction of propylene glycol monomethyl ether (PM), which is an example of glycol ether, and acetic acid (AA), which is an example of carboxylic acid.

(1)

The esterification reaction according to the present invention may reach equilibrium before the reactants are introduced into the first distillation column (V-100).

As a non-limiting example, the first reactor (R-100) according to the present invention may be a fixed bed reactor (FBR) filled with a catalyst.

More specifically, the first reactor (R-100) according to the present invention may be a fixed bed reactor (FBR) filled with a heterogeneous catalyst.

In addition, by using a heterogeneous catalyst, it is not necessary to replenish the catalyst until the life of the catalyst is exhausted, and it is possible to design a reactor and a reactive distillation column of the following stage with a material having low resistance to corrosion, and a residue catalyst. No neutralization equipment is required for the removal of

Moreover, it is possible to operate at lower temperatures than when operating with a homogeneous catalyst, and the amount of generation of impurities is minimized.

In the preparation method of the glycol ester according to the present invention, the first distillation column (V-100) reacts the glycol ether and the carboxylic acid which have passed through the first reactor (R-100) and at the same time, the unreacted substance and the product at the top. The number may be calculated and at the bottom may include all types of reactive distillation columns capable of yielding unreacted carboxylic acids and glycol esters containing impurities.

That is, in the preparation method of the glycol ester according to the present invention, the first distillation column (V-100) calculates unreacted matter and generated water at the top, and glycol containing unreacted carboxylic acid and impurities at the bottom of the tower. It may be a reaction distillation column to produce an ester.

Non-limiting, in order to perform the reaction and separation at the same time, as shown in Figure 2, in the form of a column loaded with a catalyst, all types of packing that can be filled in the column (Structured packing, Bale type packing, etc.) It may be a reaction distillation column comprising a.

Specifically, as shown in FIG. 2, the first distillation tower V-100 is formed with a rectifying zone located above and below the reactive zone while the reaction occurs in the reactive zone in which the catalyst is supported. Separation of the product and the unreacted material may proceed in the stripping zone.

In general, the esterification reaction for producing the glycol ester is an equilibrium reaction, such as the formula (1), there is a limit to the conversion that can be obtained under the reaction conditions.

However, since the first distillation column V-100 according to the present invention is separated by a column as soon as the product is produced, the partial pressure of the product in the column catalyst layer is lowered. The production rate is increased and the conversion rate can be maximized.

In this case, the glycol ether as a reactant is defined as the limiting reactant, and the conversion is defined as follows.

Overall glycol ether conversion (%) = [reactor inlet glycol ether amount-reaction distillate outflow glycol ether] / [reactor inlet glycol ether amount] x 100

Equation (1)

In the preparation method of the glycol ester according to the present invention, as the conversion rate of the glycol ether is increased, the recycle amount is reduced considerably, so that the supply amount can be efficiently controlled.

In addition, as the conversion rate increases, the loss of glycol ether to the top of the first distillation column (V-100) decreases, and there is no minimum azeotropy point of the unconverted glycol ether and the produced water.

Therefore, the loss of the glycol ester in the upper part of the first distillation column (V-100) can be minimized. As a non-limiting example, the glycol ester lost in the upper part of the glycol ester produced from the first distillation column (V-100) can be reduced. The ratio may be greater than 0 wt% and less than or equal to 1.0 wt%, preferably greater than 0 wt% and less than or equal to 0.5 wt%.

In addition, a glycol ester containing unreacted carboxylic acid and impurities may be calculated as a lower portion of the first distillation column V-100 according to the present invention.

The impurities may include other materials other than glycol ester, which is the target product according to the present invention, and may include metals in the impurities without limitation.

As a non-limiting example, the content of impurities contained in the glycol ester produced at the bottom of the first distillation column (V-100) may be more than 0 wt% to 1.0 wt% or less, preferably more than 0 wt% to 0.5 wt% or less. However, it is not limited thereto.

Method for preparing a glycol ester according to the present invention by minimizing the amount of glycol ether in the unreacted product calculated at the top of the first distillation column (V-100), so as not to generate a minimum azeotropic point of the generated water and glycol ether separate There is no need to provide a cost-effective or azeotropic distillation apparatus, and there is an advantage in that a post-separation process for recovering unconverted glycol ether and an unexpanded cost is unnecessary.

In addition, the unreacted material and the product water may be separated using the second distillation tower (V-200), and the unreacted material separated from the second distillation tower (V-200) may be the first reactor (R-100) or the first. It may be recycled to the distillation column (V-100).

The unreacted material recycled to the first reactor (R-100) is mostly carboxylic acid and may contain a small amount of glycol ether.

The recycled carboxylic acid is again the first reactor (R-100) and; The glycol ester may be prepared by reacting with glycol ether in the first distillation column (V-100).

The unreacted carboxylic acid calculated as the lower portion of the first distillation column (V-100) according to the present invention serves as a limiting substance in preparing a high purity electron glycol ester, and may be provided with a separate distillation column to separate it.

That is, the unreacted carboxylic acid calculated at the bottom of the first distillation tower (V-100) according to the present invention may be separated by using the third distillation tower (V-300) under the pressurized condition, wherein the pressurized condition is a pressure equal to or higher than the normal pressure. Means condition.

In general, in order to separate two substances having similar boiling points, distillation under reduced pressure increases the difference in relative volatilization, so that the separation is easy. However, in the case of the glycol ester and the carboxylic acid according to the present invention, the separation may be performed by increasing the pressure.

The pressurization condition may be any pressure condition above normal pressure capable of separating the glycol ester and the carboxylic acid according to the present invention. However, as the pressure increases, the lower temperature of the tower of the third distillation tower (V-300) may increase. The pressure can be set in consideration of the high temperature pyrolysis problem of the glycol ester.

As a non-limiting example, the pressure condition may be 1 to 4.0 bar, preferably 1.1 to 2.0 bar.

The third distillation column (V-300) according to the present invention can separate the unreacted carboxylic acid and the glycol ester containing impurities, thereby preparing a high-purity electronic glycol ester, and the first reactor (R- 100), the design of the present invention can be achieved injecting carboxylic acid in excess of the number of moles of glycol ether.

In the conventional method for preparing glycol esters operated under excessive injection of glycol ethers, the glycol ether and the water produced through the reactor produce a minimum azeotropic point, and the distillation boundary with the minimum azeotropic point of the glycol ester and water produced. ), Loss of glycol esters and glycol ethers occurs on top of the distillation column.

In addition, when the carboxylic acid is to be injected in excess (excess), corrosion of the carboxylic acid according to the operating temperature in the reactor or distillation column (Column) is a problem, through the separation of the carboxylic acid and glycol ester in the subsequent separation process There may be restrictions on the production of high purity products.

However, the method for preparing a glycol ester according to the present invention minimizes the unreacted amount of glycol ether passing through the first reactor (R-100) and the first distillation column (V-100) operated at a low temperature to produce distillation boundary. In addition to suppressing, by operating the third distillation column (V-300) under the pressurized condition to effectively remove the unreacted carboxylic acid calculated in the lower portion of the first distillation column (V-100), to prepare a high-purity electronic glycol ester It may enable initial overdose of carboxylic acids which may be a problem.

That is, the method for preparing a glycol ester according to the present invention may be operated by injecting a carboxylic acid in an initial flowing reactant in an excess relative to the number of moles of the glycol ether.

Here, the excessive injection means that the number of moles of carboxylic acid is greater than the number of moles of glycol ether in adjusting the molar ratio of glycol ether and carboxylic acid which are reactants flowing into the first reactor (R-100). do.

As a non-limiting example, the excessive injection amount of the carboxylic acid may be a method for producing a glycol ester of 1.01 to 1.5 moles, preferably 1.1 to 1.3 moles, relative to 1 mole of the glycol ether.

 According to the present invention, the glycol ester passed through the third distillation tower (V-300) may include impurities and may be provided with a fourth distillation tower (V-400) to remove them.

The fourth distillation column (V-400) according to the present invention includes all forms that serve to separate the pure glycol ester from impurities contained in the glycol ester.

As an example, the fourth distillation column (V-400) according to the present invention can separate the pure glycol ester to the top of the tower, it can separate the heavy impurities to the bottom of the tower.

In the process for preparing glycol esters from glycol ethers and carboxylic acids according to the invention, the glycol ethers comprise all glycol ethers for achieving the object of the invention.

As a non-limiting example, the glycol ethers according to the present invention include ethylene glycol mono butyl ether, ethylene glycol monoethyl ether, diethylene glycol mono butyl ether and the like.

As a more specific example, the glycol ether may be a method for preparing a glycol ester which is propylene glycol monomethyl ether (PM).

In the process for preparing glycol esters from glycol ethers and carboxylic acids according to the invention, the carboxylic acids may comprise all carboxylic acids capable of producing glycol esters according to the invention.

In one non-limiting embodiment, the carboxylic acid may be propionic acid, iso-butyric acid, normal-butyric acid, and the like, and in more specific example, the carboxylic acid may be a glycol ester of acetic acid (AA). It may be a manufacturing method, but is not limited thereto.

That is, when the glycol ether according to the present invention is propylene glycol monomethyl ether (PM), and the carboxylic acid is acetic acid (AA), the glycol ester prepared is propylene glycol monomethyl ether acetate (Propylene). glycol monomethyl ether acetate (PMA).

 Propylene glycol monomethyl ether acetate (PMA) prepared as described above comprises a first reactor; It may be prepared from the first, second, third and fourth distillation columns, and may be a high purity electronic propylene glycol monomethyl ether acetate (PMA) having a low content of acetic acid (AA).

The content of acetic acid includes all ranges satisfying the electronic propylene glycol monomethyl ether acetate (PMA) according to the present invention, and as a non-limiting example, the content of acetic acid is less than 20wtppm propylene glycol mono Methyl ether acetate (Propylene glycol monomethyl ether acetate: PMA) may be.

In addition, the propylene glycol monomethyl ether in the propylene glycol monomethyl ether acetate (PMA) produced according to the present invention may be 0.1wt% or less, preferably 0.05wt% or less, and metals content 20ppb or less It may be preferably 10 ppb or less.

The reaction temperature of the first reactor (R-100) according to the present invention includes all the temperature conditions of the low temperature that the carboxylic acid is not corroded, preferably 60 to 90 ℃, more preferably 70 to 80 ℃ have.

In the preparation method of the glycol ester according to the present invention, the column bottom temperature and the column top pressure of the first distillation column (V-100) include all temperature and pressure conditions for producing the glycol ester according to the present invention.

As a non-limiting embodiment, the tower bottom temperature of the first distillation column (V-100) according to the present invention may be 80C to 110 ℃, preferably 90 to 100 ℃, the pressure is 0.13 to 0.27bar, preferably Preferably it may be a method for producing a glycol ester of 0.13 to 0.2 bar.

DETAILED DESCRIPTION Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following examples, and the scope of the present invention can be easily derived by those skilled in the art. It includes.

 [ Example  1] Article 1 reactor  And 1 distillation tower  When used PM  : AA of At the mole ratio  Overall conversion rate experiment

Propylene glycol mono methyl ether (PM) and acetic acid (AA) are mixed in a molar ratio of 1: 1.3 and used as raw materials. Primary reaction in a fixed bed reactor (FBR) converts 52.14% of propylene glycol mono methyl ether (PM) to propylene glycol mono methyl ether acetate (PMA) do. At this time, the resulting product is continuously injected into the first distillation column which serves as a reaction distillation column packed with a catalyst in the middle portion of the distillation column. At this time, the operating conditions of the first distillation column is the upper pressure of 0.173319 bar, the temperature of the lower part of the tower to 98 ℃ Continuously inject raw materials while maintaining. Reflux at the top of the tower shown in FIG. 2 is maintained at 1.6. As a result of gas chromatography analysis, more than 99.9% of propylene glycol mono methyl ether (PM) was converted to propylene glycol mono methyl ether acetate (PMA).

 [ Example  2] Article 1 reactor  And when the first distillation column is used PM  : AA of At the mole ratio  Overall conversion rate experiment

 Propylene glycol mono methyl ether (PM) and acetic acid (AA) are mixed at a molar ratio of 1: 1.18 and used as raw materials. Primary reaction in a fixed bed reactor (FBR) converts 49.42% of propylene glycol mono methyl ether (PM) to propylene glycol mono methyl ether acetate (PMA) do. At this time, the produced product is continuously injected into the first distillation column, which serves as a reaction distillation column in which a catalyst is charged in the middle portion of the distillation column. Continuously inject raw materials while maintaining. Reflux at the top of the tower shown in FIG. 2 remains 2.0. As a result of gas chromatography analysis, propylene glycol mono methyl ether (PM) contained at least 99.9% of propylene glycol mono methyl ether acetate; PMA).

[ Comparative Example  One] Fixed bed  When using only reactor PM  : AA of At the mole ratio  Overall conversion rate

 In Example 1, propylene glycol mono methyl ether (PM) and acetic acid (AA) were mixed and injected into the fixed bed reactor in a molar ratio of 1: 1.3. As a result of gas chromatography analysis, only 52.14% of propylene glycol mono methyl ether (PM) was converted to propylene glycol mono methyl ether acetate (PMA).

[ Comparative Example  2] Fixed bed  When using only reactor PM  : AA of At the mole ratio  Overall conversion rate

In Example 2, propylene glycol mono methyl ether (PM) and acetic acid (AA) were mixed and mixed in a fixed bed reactor (FBR) in a molar ratio of 1: 1.18. As a result of gas chromatography analysis, only 49.42% of propylene glycol mono methyl ether (PM) was converted to propylene glycol mono methyl ether acetate (PMA).

Conversion of Glycol Ethers through Reactors and Reaction Distillation Columns driving PM: AA
Mole ratio Reactor
PM conversion rate (%) Reaction Distillation Tower PM Conversion (%) General
PM conversion rate (%) Example 1 1: 1.30 52.14 > 99.90 > 99.90 Example 2 1: 1.18 49.42 > 99.90 > 99.90 Comparative Example 1 1: 1.30 52.14 - 52.14 Comparative Example 2 1: 1.18 49.42 - 49.42

As shown in Table 1, when only a fixed bed reactor (FBR) was used, conversion of the glycol ether was limited due to the equilibrium reaction, and thus it was not possible to completely convert the glycol ether into the glycol ester. By designing the distillation column, the overall conversion can be increased.

[ Example  3] AA When used in excess, the loss to the top PMA  Ratio and impurity content in the lower PMA

As a result of gas chromatography analysis of the upper and lower compositions of the first distillation column under excess acetic acid (AA) of Example 2, propylene glycol mono methyl ether lost to the top as shown in Table 3. Acetate (PMA) ratio is 0.01wt%, Purity of propylene glycol mono methyl ether acetate (PMA) separated to the bottom is 98.5wt%, the remaining components are acetic acid (AA) 1.2wt % And impurities 0.3wt%.

[ Comparative Example  3] PM When used in excess, the loss to the top PMA  Ratio and impurity content in the lower PMA

 In Example 3, propylene glycol mono methyl ether (PM) and acetic acid (AA) were continuously injected into the first reactor in a molar ratio of 1.4: 1. The product of the first reactor was injected into the first distillation column, and the product passed through the first reactor and the first distillation column obtained a total conversion of 98% or more based on acetic acid (AA). At this time, the operating conditions of the first distillation column is the same as in the third embodiment. As a result of analyzing the top and bottom compositions of the first distillation column by gas chromatography, as shown in Table 3, the molar ratio of propylene glycol mono methyl ether acetate (PMA) lost to the top was 7.0 wt% The purity of propylene glycol mono methyl ether acetate (PMA) is 96.1 wt%, the remaining components are 1.4 wt% of acetic acid (AA), and propylene glycol mono methyl ether (PM). ) 0.1wt%, impurities were found to 2.4wt%.

<Upper PMA Loss Rate and Impurity Content in Lower PMA According to AA / PM Molar Ratio> driving PM: AA molar ratio Overall conversion rate (%) Upper PMA Loss Rate (wt%) Impurity Content in Lower PMA (wt%) Example 3 1: 1.18 99.9 0.01 0.3 Comparative Example 3 1.4: 1 98.0 7.0 2.4

As shown in Table 2, when the number of moles of acetic acid (AA) introduced into the first reactor according to the present invention is injected in excess of propylene glycol mono methyl ether (PM) The loss rate of propylene glycol mono methyl ether acetate (PMA) at the top of the first distillation column is reduced, and the propylene glycol mono methyl ether acetate (PMA) produced at the bottom of the first distillation column is reduced. It can be seen that the impurity content contained in) decreases.

[ Example  4] Article 3 distillation tower  In glycol esters under pressurized conditions AA  content

A mixture of propylene glycol mono methyl ether acetate (PMA) and acetic acid (AA) in a 95: 5 molar ratio is autoclaved at 1.1 bar. At this time, the temperature of the bottom of the third distillation column is 150 ° C, and the tower top reflux ratio (Reflux) is maintained at 65.0. The column bottom composition was analyzed by gas chromatography. The content of acetic acid (AA) in propylene glycol mono methyl ether acetate (PMA) was found to be 20wtppm.

[ Example  5] Article 3 distillation tower  In glycol esters under pressurized conditions AA  content

A mixture of propylene glycol mono methyl ether acetate (PMA) and acetic acid (AA) in a 95: 5 molar ratio is pressure-separated at 2.0 bar. At this time, the tower bottom temperature is 172 ℃, the tower top reflux ratio (Reflux) is maintained at 33.0. Acetic acid (AA) content was not observed in propylene glycol mono methyl ether acetate (PMA).

[ Example  6] Article 3 distillation tower  In glycol esters under pressurized conditions AA  content

A mixture of propylene glycol mono methyl ether acetate (PMA) and acetic acid (AA) in a 95: 5 molar ratio is autoclaved at 4.0 bar. At this time, the tower bottom temperature is 200 ℃, tower top reflux ratio (Reflux) is maintained at 30.0. Acetic acid (AA) content was not observed in propylene glycol mono methyl ether acetate (PMA).

[ Comparative Example  4] Article 3 distillation tower  Glycol esters with varying pressure conditions AA  content

A mixture of propylene glycol mono methyl ether acetate (PMA) and acetic acid (AA) in a 95: 5 molar ratio is separated at 0.5 bar. At this time, the tower bottom temperature is maintained at 128 ℃, tower top reflux ratio of 85.0. The column bottom composition was analyzed by gas chromatography. The content of acetic acid (AA) in propylene glycol mono methyl ether acetate (PMA) was 95 wtppm.

[ Comparative Example  5] Article 3 distillation tower  Glycol esters with varying pressure conditions AA  content

A mixture of propylene glycol mono methyl ether acetate (PMA) and acetic acid (AA) in a 95: 5 molar ratio is separated at 0.3 bar. At this time, the tower bottom temperature is maintained at 116 ℃, tower top reflux (Reflux) is 120.0. The column bottom composition was analyzed by gas chromatography, and the acetic acid (AA) content in propylene glycol mono methyl ether acetate (PMA) was found to be 323 wtppm.

<Reflux Ratio and AA Contents in PMA According to Pressure Conditions of Third Distillation Column> driving PMA: AA molar ratio Pressure condition (bar) Tower upper reflux ratio
(Reflux ratio) AA content in PMA Example 4 95: 5 1.1 65.0 20wtppm Example 5 95: 5 2 33.0 - Example 6 95: 5 4 30.0 - Comparative Example 4 95: 5 0.5 85.0 95wtppm Comparative Example 5 95: 5 0.3 120.0 323wtppm

As shown in Table 3, when operating the pressure condition of the third distillation column according to the present invention at normal pressure or more to acetic acid (Acetic acid) in the product propylene glycol mono methyl ether acetate (PMA); A small amount of AA) is effective in the manufacture of electronic PMA, and the reflux returning through the capacitor from the top of the column can be reduced.

According to the examples and comparative examples as described above, the method for preparing glycol ester according to the present invention enables conversion of glycol ether of 99.9% or more even at a small raw material molar ratio, and as a result, recycle quantity (recycle) is shown in Table 4. It is reduced to less than one-third of the existing PMA manufacturing process that does not utilize the device, and there is an advantage of lowering device size and utility usage.

<Comprehensive Conversion Rate Comparison by Recycle Volume> driving AA: PM molar ratio Overall conversion rate (%) Based on recycling volume of SKI PMA process SKI PMA Process 1: 1.18 99.90 1 times Existing PMA Process 1: 1.18 90.00 (Home) 3.3 times

In addition, when acetic acid (AA) is used in excess, the conventional process using glycol ether in excess is used. In an acidic atmosphere, the loss rate of propylene glycol mono methyl ether acetate (PMA) is minimized and the content of impurities is reduced. In spite of the low molar ratio injected into the reactants, the overall conversion rate is higher, so the content of unconverted propylene glycol mono methyl ether (PM) is minimized and expensive propylene glycol monomethyl ether (PM) is minimized. The utilization rate of methyl ether (PM) can be maximized and economical operating conditions can be set.

Furthermore, the acetic acid (AA) content in propylene glycol mono methyl ether acetate (PMA) at the bottom of the column due to the pressure separation conditions of the third distillation column to prepare an electronic PMA according to the present invention. Can satisfy the constraints.

Claims (15)

Reacting the glycol ether and the carboxylic acid using a first reactor and a first distillation column;
Calculating unreacted material and generated water to an upper portion of the first distillation column, and calculating a glycol ester including an unreacted carboxylic acid and impurities to a lower portion of the first distillation column;
Separating the unreacted material and the produced water using a second distillation column, and recycling the unreacted material to the first reactor or the first distillation column;
And separating the unreacted carboxylic acid calculated at the bottom of the first distillation column using a third distillation column under pressurized conditions.
The carboxylic acid introduced into the first reactor is injected in excess of the number of moles of the glycol ether,
The first distillation column is a method for producing a glycol ester, characterized in that the reaction distillation column. The method of claim 1,
Method of producing a glycol ester of the ratio of the loss to the top of the glycol ester produced from the first distillation column is more than 0wt% to 1.0wt% or less. The method of claim 1,
The tower bottom temperature of the first distillation column is 80 to 110 ℃, the pressure is 0.13 to 0.27 bar the preparation method of the glycol ester. The method of claim 1,
Method for producing a glycol ester of the impurity content contained in the glycol ester separated to the bottom of the first distillation column is more than 0wt% to 1.0wt% or less. The method of claim 1,
Excess injection of the carboxylic acid (excess) is a method for producing a glycol ester of 1.01 to 1.5 mol relative to 1 mol of glycol ether. The method of claim 1,
Wherein the first reactor is a fixed bed reactor (FBR) filled with a heterogeneous catalyst. The method of claim 1,
Process for producing a glycol ester of the reaction temperature of the first reactor is 60 to 90 ℃. The method of claim 1,
Introducing the unreacted carboxylic acid separated from the third distillation column into the second distillation column; The method of claim 8,
And separating the impurities contained in the glycol ester separated from the third distillation column using a fourth distillation column. The method according to any one of claims 1 to 9,
The glycol ether is a propylene glycol monomethyl ether (Propylene glycol monomethyl ether; PM) method for producing a glycol ester. The method according to any one of claims 1 to 9,
The carboxylic acid is acetic acid (AA) method for producing a glycol ester. The method of claim 9,
The glycol ester separated using the fourth distillation column is propylene glycol monomethyl ether acetate (PMA). 13. The method of claim 12,
The propylene glycol monomethyl ether acetate (PMA) is a method of producing a glycol ester having a content of acetic acid (AA) 20wtppm or less. 13. The method of claim 12,
Propylene glycol monomethyl ether acetate (PMA) of the propylene glycol monomethyl ether in the production method of the glycol ester is 0.1wt% or less and metals content 20ppb or less. The method according to any one of claims 1 to 9 and 12 to 14,
Method for producing a glycol ester, characterized in that the conversion of the glycol ether is 99% or more.

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