How to remove water from a mixture of PGME, PGMEA, and water.

Abstract

The present invention relates to a method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water, and is characterized by including a reactor inflow step of injecting PGME and acetic acid into a reactor, a distillation column inflow step of injecting the liquid from the reactor into a distillation column, an azeotropic agent inflow step of injecting an azeotropic agent into the upper part of the distillation column, and a condensation step of condensing a mixture of water and azeotropic agent evaporated from the upper part of the distillation column in a condenser.

Description

[Technical Field]

[0001] The present invention relates to a method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water. More specifically, the present invention relates to a method for separating water from a mixture of PGME, PGMEA, and water, which can remove water, which is produced as a by-reactant during the production of PGMEA used as an environmentally friendly solvent, from the reactants and reaction products, thereby improving the reaction rate of PGMEA production and increasing the purity of PGMEA. [Background technology]

[0002] Propylene glycol monomethyl ether acetate (PGMEA) is an environmentally friendly solvent used in a variety of applications, such as paint solvents and electronic material solvents.

[0003] Referring to Figure 1, propylene glycol monomethyl ether acetate (PGMEA) is produced by reacting propylene glycol monomethyl ether (PGME) with acetic acid in the presence of a catalyst, and water is produced as a byproduct of the reaction.

[0004] When PGMEA is produced, the water generated by the reaction must be removed to prevent a decrease in the reaction rate, and water removal is also essential to increase the purity of the produced PGMEA.

[0005] The boiling points of the reactants and reaction products at atmospheric pressure are approximately 100°C for water, 118°C for acetic acid, 120°C for PGME, and 146°C for PGMEA. Here, since the boiling point of water is the lowest at approximately 100°C, it might seem that water can be separated by evaporating it via distillation. However, at atmospheric pressure, water·PGME and water·PGMEA form an azeotrope at approximately 96°C to 98°C.

[0006] In other words, water·PGME and water·PGMEA react with water at temperatures below the boiling point of water, azeotropically and evaporating together. This reaction results in the evaporation and discharge of the reactants, PGME and water, in a weight ratio of approximately 52:48. This poses the problem of having to add and replenish the PGME needed for the reaction. Furthermore, the generated PGMEA is also discharged azeotropically with water in a weight ratio of approximately 56:44, resulting in a low reaction yield.

[0007] To address these problems, conventional methods have used toluene, which forms an azeotrope with water at a temperature lower than the azeotropic temperatures of water-PGME and water-PGMEA, as an azeotropic agent (entrainer) to remove water.

[0008] However, when toluene is used as an azeotrope, the azeotrope of water and toluene at atmospheric pressure is approximately 84.3°C, but the azeotrope of the three components water, PGME, and toluene at atmospheric pressure is lower, at approximately 83.9°C. As a result, there is a problem in that PGME and water form an azeotrope first together with toluene in a weight ratio of approximately 0.76:1, and because PGME is a water-soluble solvent, a large amount of the reactant PGME is discharged as wastewater.

[0009] In addition to using toluene as an azeotrope, conventional methods also involve using cyclohexane as an azeotrope to remove water.

[0010] However, when cyclohexane is used as an azeotropic agent, the cyclohexane-water azeotropic point is about 69.5 °C at normal pressure, but the azeotropic point of the three components of water - PGME - cyclohexane is formed at about 69 °C, which is lower than that. Moreover, there is a problem that PGME and water first azeotropically boil together at a weight ratio of about 1:1 with cyclohexane, and there still remains the problem that a large amount of the reactant PGME is lost as wastewater due to the water-soluble solvent.

[0011] In addition, conventionally, methods of using various azeotropic agents have been disclosed, but there is a problem that since the proposed azeotropic agents also azeotropically boil with PGME or PGMEA, there is no choice but to accept the loss of PGME or PGMEA (U.S. Patent Publication No. US4,544,453).

[0012] Conventionally, a method of using ethyl benzyl ether as an extractant to recover PGME from water has been used, but since water-soluble PGME is not completely extracted from water, there is a problem of PGME loss.

[0013] Also, there is a method of using pervaporation to recover PGME or PGMEA mixed with water, but such a method has a problem that it is not suitable for commercial application because it requires a very large area of pervaporation membrane.

Summary of the Invention

Problems to be Solved by the Invention

[0014] The present invention is for solving the above problems, and more specifically, when manufacturing PGMEA used as an environmentally friendly solvent, water generated as a by-product is removed from reactants and reaction products, and while improving the production reaction rate of PGMEA, it relates to a method for separating water from a mixture of PGME, PGMEA, and water that can increase the purity of PGMEA.

Means for Solving the Problems

[0015] The present invention, which solves the aforementioned problems, is a method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water, characterized by comprising: a reactor inflow step of introducing PGME and acetic acid into a reactor; a distillation column inflow step of introducing the liquid from the reactor into a distillation column; an azeotrope inflow step of introducing an entrainer into the upper part of the distillation column; and a condensation step of condensing the mixture of water evaporating from the upper part of the distillation column and the azeotrope in a condenser.

[0016] The azeotrope in the present invention, a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, also contains one or more of isopropyl acetate, ethyl acetate, and n-propyl acetate.

[0017] The present invention, which solves the aforementioned problems, provides a method for separating water from a mixture of PGME, PGMEA, and water, further comprising: a reflux step in which the liquid phase condensed in the condenser is separated into an organic layer and an aqueous layer in a flow separator, and the organic layer is refluxed to the distillation column; and a discharge step in which the liquid phase condensed in the condenser is separated into an organic layer and an aqueous layer in a flow separator, and the aqueous layer is discharged.

[0018] The catalyst for promoting the reaction between PGME and acetic acid in the present invention, a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, can be mixed with a liquid that flows into the reactor and into the distillation column.

[0019] The catalyst in the present invention, which provides a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, may also be a substance having a boiling point of 220°C or higher at atmospheric pressure, or a boiling point of 140°C or higher at 20 mmHg.

[0020] The present invention, for a method of separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, provides a solid catalyst that promotes the reaction between PGME and acetic acid, which is packed into the distillation column, and the solid catalyst may be packed below the inflow point where the liquid from the reactor flows into the distillation column.

[0021] The present invention, which addresses the aforementioned problems, provides a method for separating water from a mixture of PGME, PGMEA, and water, and further includes a reintroduction step in which the liquid discharged to the bottom of the distillation column is reintroduced into the reactor.

[0022] The present invention, which solves the aforementioned problems, provides a method for separating water from a mixture of PGME, PGMEA, and water, and the number of separation stages in the distillation column is 21 or more.

[0023] The present invention, which provides a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, has an inflow point at which the liquid from the reactor flows into the distillation column that is either approximately eight separation stages away from the top of the distillation column, or lower than approximately eight separation stages away from the top of the distillation column.

[0024] In the present invention, which provides a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, the inflow point where the liquid from the reactor flows into the distillation column is either a point approximately two separation stages away from the bottom of the distillation column, or it is above a point approximately two separation stages away from the bottom of the distillation column.

[0025] The reactor and distillation column of the present invention, which solves the aforementioned problems, for separating water from a mixture of PGME, PGMEA, and water, can also be an integrated unit.

[0026] To solve the aforementioned problems, the present invention provides a method for separating water from a mixture of PGME, PGMEA, and water. In this method, the temperature at the top of the distillation column is above the azeotropic point of the mixture of the azeotrope and water, and the temperature at the bottom of the distillation column is also the boiling point of the mixture discharged to the bottom of the distillation column.

[0027] In the present invention, which provides a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, when the azeotrope is isopropyl acetate, the upper pressure of the distillation column is 0.5 kg / cm². 2 G or -0.925 kg / cm 2 When G is present and the azeotrope is ethyl acetate, the upper pressure of the distillation column is 0.5 kg / cm². 2 G or -0.89 kg / cm 2 When G is present and the azeotrope is n-propyl acetate, the upper pressure of the distillation column is 0.5 kg / cm². 2 G or -0.96 kg / cm 2 It is also G.

[0028] In the present invention, which provides a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, the temperature at the point where the liquid from the reactor flows into the distillation column is 90°C to 140°C when the upper pressure of the distillation column is atmospheric pressure.

[0029] The distillation column of the present invention, which is a method for separating water from a mixture of PGME, PGMEA, and water to solve the aforementioned problems, also includes one or more of the following: trays, random packing, and structured packing. [Effects of the Invention]

[0030] The present invention relates to a method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water. This method has the advantage of removing water, which is produced as a by-reactant during the production of PGMEA, which is used as an environmentally friendly solvent, from the reactants and reaction products, thereby improving the reaction rate of PGMEA production.

[0031] Furthermore, the present invention has the advantage of being able to increase the purity of PGMEA by removing water, which is produced as a by-reactant during the production of PGMEA used as an environmentally friendly solvent, from the reactants and reaction products.

[0032] Furthermore, the present invention has the advantage that, when producing PGMEA, which is used as an environmentally friendly solvent, the water generated as a by-reactant during the production of PGMEA can be removed from the reactants and reaction products, thereby minimizing the leakage of reactants and reaction products, and through this, PGMEA, an environmentally friendly solvent used as a paint solvent, an electronic material solvent, etc., can be produced economically. [Brief explanation of the drawing]

[0033] [Figure 1] This figure shows the reaction equation for the reaction between propylene glycol monomethyl ether (PGME) and acetic acid in the presence of a catalyst to produce propylene glycol monomethyl ether acetate (PGMEA). [Figure 2] This is a flowchart of a method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention. [Figure 3]This figure shows a reactor and distillation column for separating water from a mixture of PGME, PGMEA, and water, according to an embodiment of the present invention. [Figure 4] This figure shows a reactor and distillation column for separating water from a mixture of PGME, PGMEA, and water, according to an embodiment of the present invention. [Figure 5] This figure shows an embodiment of the present invention in which a reactor for separating water from a mixture of PGME, PGMEA, and water, and a distillation column are formed as an integrated unit. [Figure 6] This figure shows an embodiment of the present invention in which a reactor for separating water from a mixture of PGME, PGMEA, and water, and a distillation column are formed as an integrated unit. [Figure 7] This is a compositional distribution diagram of the inside of a distillation column when isopropyl acetate is used as an azeotrope according to one embodiment of the present invention. [Figure 8] This is a compositional distribution diagram of the inside of a distillation column when ethyl acetate is used as an azeotrope, according to another embodiment of the present invention. [Figure 9] This is a compositional distribution diagram of the inside of a distillation column when n-propyl acetate is used as an azeotrope, according to yet another embodiment of the present invention. [Figure 10] This is a compositional distribution diagram of the inside of a distillation column when toluene is used as an azeotrope. [Modes for carrying out the invention]

[0034] This specification clarifies the scope of the present invention, describes the principles of the invention, and discloses embodiments so that a person with ordinary skill in the art to which the invention pertains can practice the invention. The disclosed embodiments can be embodied in a variety of forms.

[0035] Expressions such as “includes” or “also include,” which may be used in various embodiments of the present invention, indicate the existence of the disclosed function, operation, or component, but do not limit one or more further functions, operations, or components. Furthermore, in various embodiments of the present invention, terms such as “includes” or “has” should be understood to specify the existence of the features, number, stages, operations, components, parts, or combinations thereof described in the specification, but do not preemptively exclude the possibility of the existence or addition of one or more other features, numbers, stages, operations, components, parts, or combinations thereof.

[0036] When it is mentioned that one component is “connected” or “joined” with another component, it should be understood that the aforementioned component is directly connected or joined to the aforementioned other component, but that there are also new and further components between the aforementioned component and the aforementioned other component. On the other hand, when it is mentioned that one component is “directly connected” or “directly joined” with another component, it should be understood that there are no new and further components between the aforementioned component and the aforementioned other component.

[0037] The terms used herein, such as the first and second, may be used to describe a variety of components, but these components are not limited by the terms. The terms are used solely for the purpose of distinguishing one component from another. The temperatures in embodiments of the present invention are also degrees Celsius (°C).

[0038] The present invention relates to a method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water. This method can improve the purity of PGMEA while increasing the reaction rate of PGMEA production, by removing water, which is produced as a by-reactant during the production of PGMEA, an environmentally friendly solvent. The present invention will now be described in detail with reference to the attached drawings.

[0039] The method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention involves using an azeotropic agent that forms an azeotrope with water but does not form an azeotrope with acetic acid, PGME, and PGMEA at a temperature lower than the azeotropic temperature of water and the azeotropic agent (entrainer). This prevents acetic acid, PGME, and PGMEA from being leached out by azeotropic formation at a temperature lower than the azeotropic temperature of water and the azeotropic agent.

[0040] Referring to Figure 2, the method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention includes a reactor inflow step (S110), a distillation column inflow step (S120), an azeotrope inflow step (S130), and a condensation step (S140).

[0041] Referring to Figures 2 and 3, the reactor inflow step (S110) is the step of introducing PGME and acetic acid into reactor 110. According to an embodiment of the present invention, as shown in Figure 1, PGME and acetic acid may react in the presence of a catalyst to produce PGMEA. At this time, water may be produced as a byproduct.

[0042] The distillation column inflow step (S120) is the step of introducing the liquid from the reactor 110 into the distillation column 120. The distillation column 120 separates substances by vaporizing the liquid, and by introducing the liquid from the reactor 110 into the distillation column 120, water can be separated from the mixture of PGME, PGMEA, and water.

[0043] The azeotrope infusion step (S130) is a step in which an azeotrope is introduced into the upper part of the distillation column 120. The azeotrope may be used to introduce the liquid from the reactor 110 into the distillation column 120 and separate water from the mixture of PGME, PGMEA, and water.

[0044] The condensation step (S140) is a step in which the mixture of water evaporating from the top of the distillation column 120 and the azeotropic agent is condensed in the condenser 130. After the mixture of water evaporating from the top of the distillation column 120 and the azeotropic agent is condensed in the condenser 130, it may be moved to the water separator 131.

[0045] According to embodiments of the present invention, the azeotrope also contains one or more of isopropyl acetate, ethyl acetate, and n-propyl acetate.

[0046] Isopropyl acetate can be used as an azeotrope because, at atmospheric pressure, it forms an azeotrope with water in a weight ratio of approximately 8.1:1 at approximately 77°C, does not form an azeotrope with acetic acid, PGME, or PGMEA, and does not form a three-component azeotrope with water.

[0047] Ethyl acetate can be used as an azeotrope because, at atmospheric pressure, it forms an azeotrope with water in a weight ratio of approximately 10:1 at approximately 72°C, does not form an azeotrope with acetic acid, PGME, or PGMEA, and does not form a three-component azeotrope with water.

[0048] n-propyl acetate can be used as an azeotrope because, at atmospheric pressure, it forms an azeotrope with water in a weight ratio of approximately 5.3:1 at approximately 83°C, does not form an azeotrope with acetic acid, PGME, or PGMEA, and does not form a three-component azeotrope with water.

[0049] However, ethyl acetate, isopropyl acetate, and n-propyl acetate have the problem of causing the transesterification reaction of PGME in the presence of a catalyst. Therefore, in order to separate water from the mixture of PGME, PGMEA, and water while suppressing the transesterification reaction, it is necessary to prevent the mixing of PGME and the azeotropic agent in the presence of the catalyst through the distillation column 120.

[0050] For this purpose, the number of separation stages in the distillation column 120 according to the embodiment of the present invention is 21 or more, and the point at which the liquid from the reactor 110 flows into the distillation column 120 is either a point approximately 8 separation stages away from the top of the distillation column 120, or a point lower than a point approximately 8 separation stages away from the top of the distillation column 120.

[0051] If the number of separation stages in the distillation column 120 is less than 21, acetic acid, PGME, and PGMEA tend to flow out to the upper part of the distillation column 120, and acetate agents such as ethyl acetate or isopropyl acetate flow out to the lower part of the distillation column 120. In the presence of the catalyst, these come into contact with PGME and undergo side reactions, resulting in the formation of impurities.

[0052] Therefore, in order to prevent acetic acid, PGME, and PGMEA from flowing out to the upper part of the distillation column 120, or for azeotropes such as ethyl acetate and isopropyl acetate to flow out to the lower part of the distillation column 120 and come into contact with PGME in the presence of the catalyst, it is desirable that the number of separation stages in the distillation column 120 be 21 or more.

[0053] However, if the number of separation stages in the distillation column 120 is excessively large, the benefits will not be significant compared to the cost of constructing the distillation column 120. Therefore, it is desirable that the number of separation stages in the distillation column 120 be 120 or less.

[0054] Here, the distillation column 120 can form separation stages by being separated by trays provided inside the distillation column 120, and the number of separation stages of the distillation column 120 can be determined by the number of trays.

[0055] The separation stages of the distillation column 120 are not theoretical stages, but rather the actual number of stages constituting the distillation column. Furthermore, the degree of separation of substances in the distillation column 120 is related to the number of separation stages, and the tray spacing is only related to the processing capacity. Therefore, the tray spacing can be configured to 300 mm to 950 mm, which is the commonly used spacing for separation stages.

[0056] Generally, to process the same volume, if the spacing between separation stages is narrow, the diameter of the distillation column will be larger compared to when the spacing between separation stages is wide, and the tray thickness is typically 2 mm to 6 mm.

[0057] However, since the thickness of the tray is determined by the mechanical strength of the tray, taking into account the diameter of the distillation column, the thickness of the tray does not affect the separation of substances within the distillation column. Therefore, the thickness of the tray is not limited to 2 mm to 6 mm, and can be varied in various ways.

[0058] According to embodiments of the present invention, the distillation column 120 also includes one or more of the following: trays, random packing, and structured packing. The separation stage of the distillation column 120 may also consist of trays such as bubble cap trays, perforated trays, and valve trays, and the separation stage of the distillation column 120 may also consist of one of the following: structured packing or random packing.

[0059] However, not limited thereto, the separation stage of the distillation column 120 according to the embodiment of the present invention may be configured by mixing trays, random packings, structured packings, and the like.

[0060] When the distillation column 120 includes the structured packing or the random packing, the number of stages of the structured packing or the random packing can be converted into the number of trays. When the number of stages of the structured packing or the random packing is converted into the number of trays, it is desirable that the number of separation stages of the distillation column 120 is 21 or more and 120 or less.

[0061] The method for converting the number of stages of the structured packing or the random packing into the number of trays can be calculated by utilizing documents such as Perry handbook, Distillation Design (Kister), Ludwig's Applied Process Design for Chemical and Petrochemical Plants, or HETP (Height Equivalent to a Theoretical Plate) data presented by the manufacturer.

[0062] According to one embodiment, the structured packing is characterized by the surface area per unit volume, and the surface area of the structured packing used in the distillation column is 125 to 1,000 m 2 / m 3 as well. In that case, the height of the packing bed corresponding to one tray is about 800 mm to 100 mm.

[0063] That is, the surface area per unit volume is 1,000 m 2 / m 3When the distillation column 120 is constructed with structured packing, if the packing bed height is set to 2.1m, 21 separation stages can be constructed. Alternatively, the distillation column 120 can be constructed with a surface area of ​​1,000m² per unit volume. 2 / m 3 If structured packing is configured to be 1 meter high and trays are arranged in 11 layers, then 21 separation layers can be constructed.

[0064] By such a method, the number of layers in the structured packing can be converted to the number of tray layers. The method for converting the number of layers in the structured packing and the random packing to the number of tray layers is a publicly known technique, but a detailed explanation will be omitted.

[0065] According to embodiments of the present invention, the point at which the liquid from the reactor 110 flows into the distillation column 120 is preferably located at a point approximately 8 separation stages away from the top of the distillation column 120, or below a point approximately 8 separation stages away from the top of the distillation column 120.

[0066] If the point at which the liquid from reactor 110 flows into distillation column 120 is not separated by approximately 8 separation stages from the top of distillation column 120, and the liquid from reactor 110 flows in from above a point separated by approximately 8 separation stages from the top of distillation column 120, then the azeotropes, ethyl acetate, isopropyl acetate, and n-propyl acetate, will mix with PGME in the presence of the catalyst, resulting in the trans-esterification of PGME.

[0067] Specifically, the distance between the point where the liquid flows into the reactor 110 and the azeotropic agent flowing into the upper part of the distillation column 120 becomes shorter. As a result, the azeotropic agent, in the presence of the catalyst, mixes with PGME, causing a transesterification reaction of PGME, and there is a risk that acetic acid, PGME, and PGMEA will flow out to the upper part of the distillation column 120.

[0068] Therefore, it is desirable that the point at which the liquid from the reactor 110 flows into the distillation column 120 is either a point approximately eight separation stages away from the top of the distillation column 120, or a point below a point approximately eight separation stages away from the top of the distillation column 120.

[0069] According to one embodiment, if the distillation column 120 has 21 stages, the point at which the liquid from the reactor 110 flows into the distillation column 120 is either the 8th stage, which is separated from the top of the distillation column 120 by about 8 stages, or it is below the 8th stage.

[0070] Here, the azeotrope flowing into the upper part of the distillation column 120 may flow in via the uppermost stage of the distillation column 120 or the stage immediately below it. However, it is not limited to this.

[0071] Furthermore, according to embodiments of the present invention, it is desirable that the point at which the liquid from the reactor 110 flows into the distillation column 120 is located at a distance of approximately two separation stages from the bottom of the distillation column 120, or at a point above a distance of approximately two separation stages from the bottom of the distillation column 120.

[0072] However, this is not limited to that, and if the distillation column 120 has a large number of separation stages, the inflow point where the liquid from the reactor 110 flows into the distillation column 120 may be changed as necessary.

[0073] A method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention further includes a reflux step (S141) and a discharge step (S142).

[0074] Referring to Figures 2 and 3, the reflux stage (S141) is the stage in which the liquid phase condensed in the condenser 130 is separated into an organic layer and an aqueous layer in the flow separator 131, and the organic layer is refluxed to the distillation column 120. The discharge stage (S142) is the stage in which the liquid phase condensed in the condenser 130 is separated into an organic layer and an aqueous layer in the flow separator 131, and the aqueous layer is discharged.

[0075] The flow separator 131 is a device capable of separating the organic layer and the aqueous layer, and the liquid phase condensed in the condenser 130 can be separated into the organic layer and the aqueous layer via the flow separator 131.

[0076] The liquid phase condensed in the condenser 130 is a mixture of azeotropic agents (ethyl acetate, isopropyl acetate, n-propyl acetate) and water, and the organic layer separated by the flow separator 131 also contains the azeotropic agents.

[0077] The reflux step (S141) involves refluxing the organic matter layer separated via the water separator 131 to the distillation column 120, thereby allowing the azeotrope contained in the organic matter layer to flow further into the distillation column 120 via the reflux step (S141).

[0078] The discharge step (S142) involves discharging the water layer separated via the flow separator 131, and in the discharge step (S142), the water layer separated via the flow separator 131 can be discharged to the outside.

[0079] However, it is not limited to this, and in order to suppress the discharge of acetic acid, PGME, and PGMEA to the upper part of the distillation column 120, a portion of the water discharged in the aqueous layer of the water separator 131 can also be recirculated to the distillation column 120.

[0080] Here, it is desirable that the organic matter layer and aqueous layer containing the azeotrope that are refluxed to the distillation column 120 be refluxed to the top of the distillation column 120. However, considering the ease of operation of the distillation column 120, it is also possible to partially reflux the organic matter layer and aqueous layer to the middle of the distillation column 120.

[0081] However, even in that case, the reflux point of the organic matter layer must be located above the inflow point where the liquid from the reactor 110 flows into the distillation column 120 in order to prevent contact between the PGME and the azeotrope in the presence of the catalyst.

[0082] A method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention also further comprises a reinfusion step (S150).

[0083] Referring to Figures 2 and 3, the reinflow step (S150) is the step of reinflowing the liquid discharged to the bottom of the distillation column 120 into the reactor 110. By separating water via the distillation column 120, water can be separated from the liquid discharged to the bottom of the distillation column 120.

[0084] The aforementioned reinflow step (S150) is the step of reinflowing the liquid from the lower part of the distillation column 120, from which water has been separated, into the reactor 110. The liquid from the lower part of the distillation column 120 is acetic acid, PGME, PGMEA, and a catalyst. The liquid from the lower part of the distillation column 120 then goes through a continuous process of circulation between the reactor 110 and the distillation column 120, during which PGME and acetic acid react and are converted almost entirely into PGMEA. After the reaction is complete, PGMEA can be discharged from the reactor 110.

[0085] In the reinflow step (S150), after the liquid at the bottom of the distillation column 120 is reinflowed into the reactor 110, the liquid at the bottom of the distillation column 120 circulates between the reactor 110 and the distillation column 120. During this time, a reaction continues in which acetic acid, PGME, and a catalyst produce PGMEA and water, and the water produced in the reaction can be removed from the distillation column 120.

[0086] Referring to Figure 4, as the temperature of the reactor 110 rises, some gas may be generated in the reactor 110, and this gas generated in the reactor 110 may flow into the distillation column 120.

[0087] Referring to Figure 5, the reactor 110 and the distillation column 120 according to the embodiment of the present invention can also be integrated. The reactor 110 is provided at the lower part of the distillation column 120, and the reactor 110 and the distillation column 120 can be configured as an integrated unit.

[0088] By integrating the reactor 110 and the distillation column 120, the installation space for the apparatus can be reduced, and the liquid at the bottom of the distillation column 120 is re-flowed into the reactor 110 via the down cam 123 of the collector tray 122 located at the bottom of the distillation column 120, thus eliminating the need for a separate liquid transfer device.

[0089] In this case, the distillation column 120 is equipped with a reboiler 121, which can reheat the liquid. Also, referring to Figure 6, the reboiler 121 may be provided in the reactor 110.

[0090] According to embodiments of the present invention, the catalyst that promotes the reaction between PGME and acetic acid may be mixed with the liquid that flows into the reactor 110 and into the distillation column 120.

[0091] The catalyst flowing into the reactor 110 may be a substance having a boiling point of 220°C or higher at atmospheric pressure, or a boiling point of 140°C or higher at 20 mmHg. Specifically, it is desirable that the catalyst be a substance having a boiling point of 220°C or higher at atmospheric pressure, which is sufficiently higher than the boiling point of PGMEA, which is 146°C.

[0092] If the boiling point of the catalyst is lower than 220°C, the catalyst may boil and rise to the top of the inlet point of the distillation column 120, thereby mixing with the azeotrope and causing the transesterification reaction of PGME. Therefore, it is desirable that the catalyst flowing into the reactor 110 be a substance whose boiling point at atmospheric pressure is 220°C or higher.

[0093] Here, when measuring the boiling point of the catalyst, if the temperature is raised to 220°C at atmospheric pressure, the catalyst may decompose, making it impossible to measure the boiling point. Therefore, the boiling point of the catalyst is measured under temperature conditions that do not cause the catalyst to decompose, and thus the catalyst can also be a substance whose boiling point at 20 mmHg is 140°C or higher.

[0094] According to embodiments of the present invention, a solid catalyst that promotes the reaction between PGME and acetic acid is packed into the distillation column 120, and the solid catalyst may be packed below the inflow point where the liquid from the reactor 110 flows into the distillation column 120.

[0095] According to embodiments of the present invention, the catalyst is also a solid catalyst, and the catalyst is also a solid catalyst that is not dissolved by the reactants. When the catalyst is a solid catalyst that is not dissolved by the reactants, the solid catalyst can be packed into the lower part of the inflow point where the liquid from the reactor 110 flows into the distillation column 120.

[0096] By filling the lower part of the inflow point where the liquid from the reactor 110 flows into the distillation column 120 with the solid catalyst, the distillation column 120 can simultaneously perform the roles of both the reactor 110 and the distillation column 120.

[0097] In this case as well, the conditions for configuring the azeotrope so that it does not come into contact with PGME in the presence of the catalyst are the same as those described above, and the operating conditions are also the same as those described later. The method for packing the distillation column 120 with the solid catalyst is to pack the solid catalyst in a section separate from the separation stage, or to pack it by attaching it to trays, random packing, structured packing, etc.

[0098] However, the catalyst may also be introduced into the reactor 110, and may be introduced into and filled into one or more of either the reactor 110 or the distillation column 120.

[0099] According to an embodiment of the present invention, the temperature at the top of the distillation column 120 is above the azeotropic point of the mixture of the azeotrope and the water, and the temperature at the bottom of the distillation column 120 is also the boiling point of the mixture discharged to the bottom of the distillation column 120.

[0100] Only by setting the temperature at the top of the distillation column 120 to a temperature above the azeotropic point of the mixture of the azeotropic agent and water can the mixture of the azeotropic agent and water be evaporated and the water separated. Therefore, the temperature at the top of the distillation column 120 can be determined via the azeotropic point of the mixture of the azeotropic agent and water. Furthermore, the temperature at the bottom of the distillation column 120 is also the boiling point of the mixture (PGMEA, catalyst, etc.) discharged to the bottom of the distillation column 120.

[0101] According to an embodiment of the present invention, when the azeotrope is isopropyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.925 kg / cm 2 When G is present and the azeotrope is ethyl acetate, the upper pressure of the distillation column is 0.5 kg / cm². 2 G or -0.89 kg / cm 2 When G is present and the azeotrope is n-propyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.96 kg / cm 2 It is also G.

[0102] Although the azeotrope is isopropyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.925 kg / cm 2 When the temperature is G, the temperature at the top of the distillation column 120 can be adjusted to approximately 88°C to approximately 25°C, and the temperature at the bottom of the distillation column 120 can be adjusted to approximately 160°C to approximately 82°C.

[0103] Here, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 If the temperature is higher than G, there is a risk that impurities will be generated due to the decomposition of PGMEA, as the temperature at the bottom of the distillation column 120 will exceed 160°C.

[0104] Furthermore, the pressure at the top of the distillation column 120 is -0.925 kg / cm². 2 If the pressure is lower than G, the gas temperature at the top of the distillation column 120 will fall below 25°C, resulting in an uneconomical process configuration where a refrigerator must be used to condense the gas. Therefore, when the azeotrope is isopropyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.925 kg / cm 2 It is preferable that it be G.

[0105] Although the azeotrope is ethyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.89 kg / cm 2 When the temperature is G, the temperature at the top of the distillation column 120 can be adjusted to approximately 83°C to approximately 25°C, and the temperature at the bottom of the distillation column 120 can be adjusted to approximately 160°C to approximately 88°C.

[0106] Here, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 If the temperature is higher than G, there is a risk that impurities will be generated due to the decomposition of PGMEA, as the temperature at the bottom of the distillation column 120 will exceed 160°C.

[0107] Furthermore, the pressure at the top of the distillation column 120 was -0.89 kg / cm². 2If the pressure is lower than G, the gas temperature at the top of the distillation column 120 will fall below 25°C, resulting in an uneconomical process configuration where a refrigerator must be used to condense the gas. Therefore, when the azeotrope is ethyl acetate, the pressure at the top of the distillation column 120 should be 0.5 kg / cm². 2 G or -0.89 kg / cm 2 It is preferable that it be G.

[0108] Although the azeotrope is n-propyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.96 kg / cm 2 When the temperature is G, the temperature at the top of the distillation column 120 can be adjusted to approximately 95°C to approximately 25°C, and the temperature at the bottom of the distillation column 120 can be adjusted to approximately 160°C to approximately 73°C.

[0109] Here, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 If the temperature is higher than G, there is a risk that impurities will be generated due to the decomposition of PGMEA, as the temperature at the bottom of the distillation column 120 will exceed 160°C.

[0110] Furthermore, the pressure at the top of the distillation column 120 was -0.96 kg / cm². 2 If the pressure is lower than G, the gas temperature at the top of the distillation column 120 will fall below 25°C, resulting in an uneconomical process configuration where a refrigerator must be used to condense the gas. Therefore, when the azeotrope is n-propyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.96 kg / cm 2 It is preferable that it be G.

[0111] According to an embodiment of the present invention, the temperature at the point where the liquid from the reactor 110 flows into the distillation column 120 is 90°C to 140°C when the upper pressure of the distillation column 120 is atmospheric pressure, and the upper pressure of the distillation column 120 is -0.625 kg / cm². 2 When it is G, it is also 65°C or 115°C.

[0112] If the temperature at the point where the liquid from the reactor 110 flows into the distillation column 120 is excessively low, the azeotropic agent flowing into the upper part of the distillation column 120 will reach the point of inflow, and there it may come into contact with PGME under the catalyst and undergo a transesterification reaction.

[0113] Furthermore, if the temperature at the inflow point where the liquid from the reactor 110 flows into the distillation column 120 is excessively high, the catalyst flowing in from the reactor 110 will rise to the top of the inflow point, and the azeotrope may come into contact with PGME under the catalyst, potentially causing a transesterification reaction.

[0114] In other words, if the temperature at the point where the liquid from the reactor 110 flows into the distillation column 120 is excessively low or high, the azeotropic agent flowing into the upper part of the distillation column 120 may descend, or the catalyst flowing in through the reactor 110 may rise to the upper part of the distillation column 120, potentially causing the azeotropic agent to come into contact with PGME under the catalyst and undergo a transesterification reaction.

[0115] Therefore, the temperature at the point where the liquid from the reactor 110 flows into the distillation column 120 is preferably 90°C to 140°C when the upper pressure of the distillation column 120 is atmospheric pressure, and the upper pressure of the distillation column 120 is -0.625 kg / cm². 2 When the temperature is G, it is desirable that it be between 65°C and 115°C.

[0116] However, according to embodiments of the present invention, the temperature at the point where the liquid from the reactor 110 flows into the distillation column 120 is changed by the pressure at the top of the distillation column 120, and also differs from the pressure at the point of inflow determined by the pressure loss inside the distillation column 120, and from the liquid composition formed at the point of inflow.

[0117] The method for separating water from a mixture of PGME, PGMEA, and water, as described in the embodiments of the present invention, allows for the continuous removal of water generated during the reaction while suppressing the transesterification reaction of PGME, thereby preventing the loss of the reactants, acetic acid and PGME, and the reaction product, PGMEA, through water, and thereby improving reactivity.

[0118] In addition, by setting the number of separation stages in the distillation column 120 to 21, and by forming the inflow point where the liquid from the reactor 110 flows into the distillation column 120 at a point approximately 8 separation stages away from the top of the distillation column 120, or below a point approximately 8 separation stages away from the top of the distillation column 120, the concentration of the azeotrope in the liquid phase at the inflow point where the liquid from the reactor 110 flows in can be maintained at 100 ppm by weight or less.

[0119] Furthermore, by setting the number of separation stages in the distillation column 120 to 21, and by positioning the point where the liquid from the reactor 110 flows into the distillation column 120 at a distance of approximately 8 separation stages from the top of the distillation column 120, or below a distance of approximately 8 separation stages from the top of the distillation column 120, it is possible to maintain the concentration of the azeotrope in the liquid discharged to the bottom of the distillation column 120 and flowing into the reactor 110 at 10 ppm by weight or less, while minimizing the transesterification reaction of PGME.

[0120] In the following description, the effects of the present invention will be explained through examples and comparative examples of a method for separating water from a mixture of PGME, PGMEA, and water according to embodiments of the present invention.

[0121] [Example 1]

[0122] In one embodiment of the present invention, the distillation column 120 was configured with 21 separation stages, and a mixture of water, acetic acid, PGME, PGMEA, and a catalyst was introduced from the reactor 110 to the middle of the distillation column 120, while isopropyl acetate, an azeotrope, was introduced to the upper part of the distillation column 120. The catalyst used was p-toluenesulfonic acid (PTSA), which has a boiling point of 140°C at 20 mmHg.

[0123] The temperature at the top of the distillation column 120 is determined by the azeotropic point of the azeotropic agent and water, and the pressure at the top of the distillation column 120. The temperature at the top of the distillation column 120 was set to approximately 77°C while operating the column with atmospheric pressure at the top.

[0124] The temperature at the bottom of the distillation column 120 is determined by the boiling point of the liquid phase composition mixture discharged to the bottom of the distillation column 120 and the pressure at the bottom of the distillation column, and was set to approximately 135°C.

[0125] The temperature of the upper constant separation stage above the inflow point where the liquid flows from the reactor 110 to the distillation column 120 was adjusted to approximately 97°C so that the azeotrope would not reach the inflow point and the catalyst that flowed into the inflow point would not mix with the azeotrope.

[0126] The temperature of the liquid flowing from the reactor 110 into the distillation column 120 is set to approximately 60°C to 135°C, as the liquid discharged to the bottom of the distillation column 120 flows back into the reactor 110 and then flows back into the distillation column.

[0127] Here, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is not higher than the boiling point at the bottom of the distillation column 120 in order to prevent a large amount of catalyst from evaporating at the top of the inflow point.

[0128] Furthermore, if the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is lower than 60°C, the energy used in the reboiler will be excessive. Therefore, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 be higher than 60°C.

[0129] As the reaction progresses, the temperature at the bottom of the distillation column 120 changes as the composition of the liquid discharged to the bottom of the distillation column 120 changes. Therefore, the highest temperature at the end of the reaction is also the boiling point of the catalyst and PGMEA.

[0130] In other words, according to embodiments of the present invention, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is higher than 60°C and lower than the temperature at the bottom of the distillation column 120.

[0131] The temperature of a certain upper stage at the point where the liquid flows from the reactor 110 into the distillation column 120 is determined by which stage is used as the reference point, but the temperature is also between the temperature at the point of inflow and the temperature of the top stage of the distillation column 120. The temperature at the point of inflow is approximately 113°C, or it is also the boiling point of the liquid composition formed at the point of inflow at that pressure, so the temperature at the point of inflow can change as the reaction progresses.

[0132] Figure 7 is a compositional distribution diagram of the inside of the distillation column 120 when isopropyl acetate is used as an azeotrope. Referring to Figure 7, the above method ensures that the concentrations of acetic acid, PGME, and PGMEA in the gas discharged to the top of the distillation column 120 are 100 ppm by weight or less, and that the azeotrope does not mix with PGME in the presence of the catalyst inside the distillation column 120, while also preventing the azeotrope from flowing out to the bottom of the distillation column 120.

[0133] Specifically, referring to Figure 7, it can be seen that there is no PGME or PGMEA flowing out to the upper part of the distillation column 120, and no azeotropic agent flowing out to the lower part of the distillation column 120, and that there is no section within the distillation column 120 where the azeotropic agent mixes with PGME in the presence of the catalyst (referring to Figure 7, there is no section within the distillation column 120 where the azeotropic agent, catalyst, and PGME are present together).

[0134] In another embodiment of the present invention, the pressure at the top of the distillation column 120 can also be changed. However, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.925 kg / cm 2 It can be adjusted between G.

[0135] The upper pressure of the distillation column 120 was set to -0.625 kg / cm². 2 When operating at G, even if the temperature at the top of the distillation column 120 is adjusted to approximately 53°C, the temperature at the bottom of the distillation column 120 is adjusted to approximately 115°C, and the temperature at the constant separation stage above the inflow point where liquid flows from the reactor 110 into the distillation column 120 is adjusted to 71°C, the concentration of PGME and PGMEA in the gas discharged to the top of the distillation column 120 is 100 ppm by weight or less. This allows the distillation column 120 to be operated in such a way that the azeotrope does not mix with PGME in the presence of the catalyst, and prevents the azeotrope from flowing out to the bottom of the distillation column 120.

[0136] [Example 2]

[0137] In another embodiment of the present invention, the distillation column 120 is configured with 21 separation stages, and a mixture of water, acetic acid, PGME, PGMEA, and a catalyst is introduced from the reactor 110 to the middle of the distillation column 120, while ethyl acetate, an azeotrope, is introduced to the upper part of the distillation column 120. The catalyst used is p-toluenesulfonic acid (PTSA), which has a boiling point of 140°C at 20 mmHg.

[0138] The temperature at the top of the distillation column 120 is determined by the azeotropic point of the azeotropic agent and water, and the pressure at the top of the distillation column 120. The temperature at the top of the distillation column 120 was raised to approximately 72°C while operating the column with atmospheric pressure at the top.

[0139] The temperature at the bottom of the distillation column 120 is determined by the boiling point of the liquid phase composition mixture discharged to the bottom of the distillation column 120 and the pressure at the bottom of the distillation column, and was set to approximately 135°C.

[0140] The temperature of the upper constant separation stage above the inflow point where the liquid flows from the reactor 110 to the distillation column 120 was adjusted to approximately 93°C so that the azeotrope would not reach the inflow point and the catalyst that had flowed into the inflow point would not mix with the azeotrope.

[0141] The temperature of the liquid flowing from the reactor 110 into the distillation column 120 is set to approximately 60°C to 135°C, as the liquid discharged to the bottom of the distillation column 120 flows back into the reactor 110 and then flows back into the distillation column.

[0142] Here, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is not higher than the boiling point at the bottom of the distillation column 120 in order to prevent a large amount of catalyst from evaporating at the top of the inflow point.

[0143] Furthermore, if the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is lower than 60°C, the energy used in the reboiler is excessive. Therefore, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 be higher than 60°C.

[0144] As the reaction progresses, the temperature at the bottom of the distillation column 120 changes as the composition of the liquid discharged to the bottom of the distillation column 120 changes. Therefore, the highest temperature at the end of the reaction is also the boiling point of the catalyst and PGMEA.

[0145] In other words, according to embodiments of the present invention, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is higher than 60°C and lower than the temperature at the bottom of the distillation column 120.

[0146] The temperature of a fixed upper stage at the point where the liquid flows from the reactor 110 into the distillation column 120 is determined by which stage is used as the reference point, and this temperature is between the temperature at the point of inflow and the temperature of the uppermost stage of the distillation column 120. Since the temperature at the point of inflow is approximately 108°C, or the boiling point of the liquid composition formed at the point of inflow at that pressure, the temperature at the point of inflow may change as the reaction progresses.

[0147] Figure 8 is a compositional distribution diagram of the inside of the distillation column 120 when ethyl acetate is used as an azeotrope. Referring to Figure 8, the above method makes it possible to ensure that the concentrations of acetic acid, PGME, and PGMEA in the gas discharged to the top of the distillation column 120 are 100 ppm by weight or less, and that the azeotrope does not flow out to the bottom of the distillation column 120 while preventing the azeotrope from mixing with PGME in the presence of the catalyst inside the distillation column 120.

[0148] Specifically, referring to Figure 8, it can be seen that there is no PGME or PGMEA flowing out to the upper part of the distillation column 120, and no azeotropic agent flowing out to the lower part of the distillation column 120, and that there is no section within the distillation column 120 where the azeotropic agent is mixed with PGME in the presence of the catalyst (referring to Figure 8, there is no section within the distillation column 120 where the azeotropic agent, catalyst, and PGME are present together).

[0149] In another embodiment of the present invention, the pressure at the top of the distillation column 120 can also be changed. However, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.89 kg / cm 2 It can be adjusted between G.

[0150] The upper pressure of the distillation column 120 was set to -0.625 kg / cm². 2 When operating at setting G, even if the upper temperature of the distillation column 120 is adjusted to approximately 48°C, the lower temperature of the distillation column 120 is adjusted to approximately 115°C, and the temperature of the constant separation stage above the inflow point where liquid flows from the reactor 110 into the distillation column 120 is adjusted to 52°C, the concentration of PGME and PGMEA in the gas discharged to the upper part of the distillation column 120 will be 100 ppm by weight or less. This allows the distillation column 120 to be operated in such a way that the azeotrope does not mix with PGME in the presence of the catalyst, and prevents the azeotrope from flowing out to the lower part of the distillation column 120.

[0151] [Embodiment 3]

[0152] In one embodiment of the present invention, the distillation column 120 was configured with 21 separation stages, and a mixture of water, acetic acid, PGME, PGMEA, and a catalyst was introduced from the reactor 110 to the middle of the distillation column 120, while n-propyl acetate, an azeotrope, was introduced to the upper part of the distillation column 120. The catalyst used was p-toluenesulfonic acid (PTSA), which has a boiling point of 140°C at 20 mmHg.

[0153] The temperature at the top of the distillation column 120 is determined by the azeotropic point of the azeotropic agent and water, and the pressure at the top of the distillation column 120. The temperature at the top of the distillation column 120 was raised to approximately 83°C while operating the column with atmospheric pressure at the top.

[0154] The temperature at the bottom of the distillation column 120 is determined by the boiling point of the liquid phase composition mixture discharged to the bottom of the distillation column 120 and the pressure at the bottom of the distillation column, and was set to approximately 135°C.

[0155] The temperature of the upper constant separation stage above the inflow point where the liquid flows from the reactor 110 into the distillation column 120 was adjusted to approximately 116°C so that the azeotrope would not reach the inflow point and the catalyst that had flowed into the inflow point would not mix with the azeotrope.

[0156] The temperature of the liquid flowing from the reactor 110 into the distillation column 120 is set to approximately 60°C to 135°C, as the liquid discharged to the bottom of the distillation column 120 flows back into the reactor 110 and then flows back into the distillation column.

[0157] Here, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is not higher than the boiling point at the bottom of the distillation column 120 in order to prevent a large amount of catalyst from evaporating at the top of the inflow point.

[0158] Furthermore, if the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is lower than 60°C, the energy used in the reboiler is excessive. Therefore, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 be higher than 60°C.

[0159] As the reaction progresses, the temperature at the bottom of the distillation column 120 changes as the composition of the liquid discharged to the bottom of the distillation column 120 changes. Therefore, the highest temperature at the end of the reaction is also the boiling point of the catalyst and PGMEA.

[0160] In other words, according to embodiments of the present invention, it is desirable that the temperature of the liquid flowing from the reactor 110 into the distillation column 120 is higher than 60°C and lower than the temperature at the bottom of the distillation column 120.

[0161] The temperature of a certain upper stage at the point where the liquid flows from the reactor 110 into the distillation column 120 is determined by which stage is used as the reference point, and this temperature is between the temperature at the point of inflow and the temperature of the uppermost stage of the distillation column 120. The temperature at the point of inflow is approximately 127°C, or it is also the boiling point of the liquid composition formed at the point of inflow at that pressure, and therefore the temperature at the point of inflow may change as the reaction progresses.

[0162] Figure 9 is a compositional distribution diagram of the inside of the distillation column 120 when n-propyl acetate is used as an azeotrope. Referring to Figure 9, the above method ensures that the concentrations of acetic acid, PGME, and PGMEA in the gas discharged to the top of the distillation column 120 are 100 ppm by weight or less, and that the azeotrope does not flow out to the bottom of the distillation column 120 while preventing the azeotrope from mixing with PGME in the presence of the catalyst inside the distillation column 120.

[0163] Specifically, referring to Figure 9, it can be seen that because there is no PGME or PGMEA flowing out to the upper part of the distillation column 120, no azeotropic agent flows out to the lower part of the distillation column 120, and therefore there is no section within the distillation column 120 where the azeotropic agent mixes with PGME in the presence of the catalyst (referring to Figure 9, there is no section within the distillation column 120 where the azeotropic agent, catalyst, and PGME are present together).

[0164] In another embodiment of the present invention, the pressure at the top of the distillation column 120 can also be changed. However, the pressure at the top of the distillation column 120 is 0.5 kg / cm². 2 G or -0.96 kg / cm 2 It can be adjusted between G.

[0165] The upper pressure of the distillation column 120 was set to -0.625 kg / cm². 2 When operating at setting G, even if the upper temperature of the distillation column 120 is adjusted to approximately 60°C, the lower temperature of the distillation column 120 is adjusted to approximately 116°C, and the temperature of the constant separation stage above the inflow point where liquid flows from the reactor 110 into the distillation column 120 is adjusted to 90°C, the concentration of PGME and PGMEA in the gas discharged to the upper part of the distillation column 120 is 100 ppm by weight or less, and the distillation column 120 can be operated in such a way that the azeotrope does not mix with PGME in the presence of the catalyst, and the azeotrope does not flow out to the lower part of the distillation column 120.

[0166] In embodiments of the present invention, isopropyl acetate, ethyl acetate, and n-propyl acetate are partially converted to isopropyl alcohol, ethyl alcohol, and n-propyl alcohol, respectively. These alcohols form an azeotrope with water and can be discharged to the top of the distillation column.

[0167] The aforementioned alcohol can be removed in certain quantities by transferring the aqueous layer of the water separator to a separate distillation column and performing distillation or extraction. Any alcohol that is not removed may reflux into the distillation column along with the azeotrope, but since it forms an azeotrope with water together with the azeotrope, it may be discharged to the top of the distillation column.

[0168] The alcohol mixed with the azeotrope in the organic matter layer of the water separator can be removed in a certain amount in a separate distillation column. At atmospheric pressure, isopropyl acetate and isopropyl alcohol, ethyl acetate and ethyl alcohol, n-propyl acetate and n-propyl alcohol each form an azeotrope. Therefore, by operating the separate distillation column at a high pressure, the composition of the azeotropic alcohols can be reduced, and a certain amount can be removed.

[0169] [Comparative Example]

[0170] In the comparative example, the distillation column was configured with 21 separation stages. Water, acetic acid, PGME, PGMEA, and a catalyst mixture were introduced from the reactor into the middle of the distillation column, while the azeotrope was converted to toluene and introduced into the upper part of the distillation column. The pressure at the top of the distillation column was -0.625 kg / cm². 2 When operating in G mode, the temperature at the top of the distillation column was set to 62°C and the temperature at the bottom of the distillation column was set to 115°C.

[0171] Figure 10 shows the compositional distribution inside the distillation column when toluene is used as an azeotrope. Referring to Figure 10, when toluene is used as an azeotrope, the concentrations of acetic acid and PGMEA in the gas discharged to the top of the distillation column were less than 100 ppm by weight, but the concentration of PGME was approximately 14% by weight, indicating that a large amount of PGME was discharged to the top of the distillation column.

[0172] This is because the three components—water, PGME, and toluene—form an azeotrope at the lowest temperature. Since PGME is a water-soluble solvent, a large amount of PGME is contained in the aqueous layer and leaches out in the liquid phase where it condenses. When toluene is used as an azeotrope, it was not possible to prevent PGME from flowing out to the top of the distillation column, regardless of the method used to adjust the temperature above the point where the liquid flows from the reactor into the distillation column.

[0173] In other words, as in the embodiments of the present invention, when the azeotropic agent is used as isopropyl acetate, ethyl acetate, or n-propyl acetate, it is possible to prevent PGME and PGMEA from flowing out to the upper part of the distillation column 120 and to prevent the azeotropic agent from flowing out to the lower part of the distillation column 120, while eliminating the section in the distillation column 120 where the azeotropic agent is mixed with PGME in the presence of the catalyst. However, as in the comparative example, when an azeotropic agent such as toluene that azeotropes with PGME, or an azeotropic agent that azeotropes with PGMEA is used, there is a problem in that it is difficult to prevent PGME and PGMEA from flowing out to the upper part of the distillation column.

[0174] Thus, the method for separating water from a mixture of PGME, PGMEA, and water according to the embodiments of the present invention can remove water, which is produced as a by-reactant during the production of PGMEA used as an environmentally friendly solvent, from the reactants and reaction products, thereby improving the reaction rate of PGMEA production and increasing the purity of PGMEA.

[0175] The method for separating water from a mixture of PGME, PGMEA, and water, according to the embodiments of the present invention described above, has the following effects.

[0176] The method for separating water from a mixture of PGME, PGMEA, and water according to embodiments of the present invention has the advantage of removing water, which is produced as a by-reactant during the production of PGMEA used as an environmentally friendly solvent, from the reactants and reaction products, thereby improving the reaction rate of PGMEA production.

[0177] Furthermore, the method for separating water from a mixture of PGME, PGMEA, and water according to the embodiments of the present invention has the advantage of being able to increase the purity of PGMEA by removing water, which is produced as a by-reactant during the production of PGMEA used as an environmentally friendly solvent, from the reactants and reaction products.

[0178] Furthermore, the method for separating water from a mixture of PGME, PGMEA, and water according to embodiments of the present invention has the advantage of minimizing the loss of reactants and reaction products by removing water, which is produced as a by-reactant during the production of PGMEA used as an environmentally friendly solvent, from the reactants and reaction products, thereby enabling the economical production of PGMEA, an environmentally friendly solvent used as a paint solvent, an electronic material solvent, and the like.

[0179] As described above, the present invention has been explained with reference to an embodiment illustrated in the drawings, but these are merely illustrative, and a person with ordinary skill in the art will understand that a variety of modifications and variations of embodiments are possible from them. Accordingly, the true scope of technical protection of the present invention is determined by the technical idea of ​​the appended claims. Furthermore, this application includes the following aspects. [Section 1] In a method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water, The reactor inflow step involves introducing PGME and acetic acid into the reactor, A distillation column inflow step in which the liquid from the reactor is introduced into the distillation column, The azeotrope infusion step involves introducing an azeotrope into the upper part of the aforementioned distillation column, A method for separating water from a mixture of PGME, PGMEA, and water, characterized by comprising a condensation step of condensing a mixture of water evaporating from the top of the distillation column and an azeotropic agent in a condenser. [Section 2] The aforementioned azeotrope is A method for separating water from a mixture of PGME, PGMEA, and water according to item 1, characterized by containing one or more of isopropyl acetate, ethyl acetate, and n-propyl acetate. [Section 3] The liquid phase condensed in the condenser is separated into an organic layer and an aqueous layer in a flow separator, and the organic layer is refluxed to the distillation column in a reflux step. A method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, further comprising a discharge step of separating the liquid phase condensed in the condenser into an organic matter layer and an aqueous layer in a flow separator, and discharging the aqueous layer. [Section 4] The catalyst that promotes the reaction between the PGME and the acetic acid is A method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the mixture is introduced into the reactor and mixed with a liquid introduced into the distillation column. [Section 5] The method for separating water from a mixture of PGME, PGMEA, and water according to item 4, characterized in that the catalyst is a substance whose boiling point is 220°C or higher at normal pressure, or whose boiling point is 140°C or higher at 20 mmHg. [Section 6] The solid catalyst that promotes the reaction between the PGME and the acetic acid is packed into the distillation column. The method for separating water from a mixture of PGME, PGMEA, and water according to item 1, characterized in that the solid catalyst is packed at the bottom of the inflow point where the liquid of the reactor flows into the distillation column. [Section 7] The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, further comprising a reinflow step of reintroducing the liquid discharged to the lower part of the distillation column back into the reactor. [Section 8] The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the number of separation stages in the distillation column is 21 or more. [Section 9] The point at which the liquid from the reactor flows into the distillation column is: A method for separating water from a mixture of PGME, PGMEA, and water according to item 1, characterized in that the location is at a point approximately 8 separation stages away from the top of the distillation column, or below a point approximately 8 separation stages away from the top of the distillation column. [Section 10] The point at which the liquid from the reactor flows into the distillation column is: A method for separating water from a mixture of PGME, PGMEA, and water according to item 1, characterized in that the location is a point approximately two separation stages away from the bottom of the distillation column, or above a point approximately two separation stages away from the bottom of the distillation column. [Section 11] The method for separating water from a mixture of PGME, PGMEA, and water according to item 1, characterized in that the reactor and the distillation column are integrated into a single unit. [Section 12] The temperature at the top of the distillation column is above the azeotropic point of the mixture of the azeotropic agent and the water. The method for separating water from a mixture of PGME, PGMEA, and water according to item 1, characterized in that the temperature at the bottom of the distillation column is the boiling point of the mixture discharged to the bottom of the distillation column. [Section 13] When the azeotrope is isopropyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm². 2 G or -0.925 kg / cm 2 It is also G, When the azeotrope is ethyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm². 2 G or -0.89 kg / cm 2 It is also G, When the azeotrope is n-propyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm². 2 G or -0.96 kg / cm 2 A method for separating water from a mixture of PGME, PGMEA, and water as described in item 2, characterized in that it is G. [Section 14] The temperature at the point where the liquid from the reactor flows into the distillation column is: A method for separating water from a mixture of PGME, PGMEA, and water according to item 1, characterized in that the upper pressure of the distillation column is at atmospheric pressure and the temperature is 90°C to 140°C. [Section 15] The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the distillation column includes one or more of the following: trays, random packing, and structured packing.

Claims

1. In a method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water, The reactor inflow step involves introducing PGME and acetic acid into the reactor, A distillation column inflow step in which the liquid from the reactor is introduced into the distillation column, The azeotrope infusion step involves introducing an azeotrope into the upper part of the aforementioned distillation column, The process includes a condensation step in which a mixture of water evaporating from the top of the distillation column and an azeotropic agent is condensed in a condenser, The aforementioned azeotrope is It contains one or more of isopropyl acetate, ethyl acetate, and n-propyl acetate. The number of separation stages in the aforementioned distillation column is 21 or more. The point at which the liquid from the reactor flows into the distillation column is: The location is either eight separation stages away from the top of the distillation column, or it is below the point eight separation stages away from the top of the distillation column. The point at which the liquid from the reactor flows into the distillation column is: A method for separating water from a mixture of PGME, PGMEA, and water, characterized in that the location is either two separation stages away from the bottom of the distillation column, or above a location two separation stages away from the bottom of the distillation column.

2. The liquid phase condensed in the condenser is separated into an organic layer and an aqueous layer in a flow separator, and the organic layer is refluxed to the distillation column in a reflux step. The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, further comprising a discharge step of separating the liquid phase condensed in the condenser into an organic matter layer and an aqueous layer in a flow separator, and discharging the aqueous layer.

3. The catalyst that promotes the reaction between the PGME and the acetic acid is A method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the mixture is introduced into the reactor and mixed with a liquid introduced into the distillation column.

4. The method for separating water from a mixture of PGME, PGMEA, and water according to claim 3, characterized in that the catalyst is a substance whose boiling point is 220°C or higher at normal pressure, or 140°C or higher at 20 mmHg.

5. The solid catalyst that promotes the reaction between the PGME and the acetic acid is packed into the distillation column. The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the solid catalyst is packed at the bottom of the inflow point where the liquid of the reactor flows into the distillation column.

6. The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, further comprising a reinflow step of reinflowing the liquid discharged to the lower part of the distillation column into the reactor.

7. The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the reactor and the distillation column are integrated into one unit.

8. The temperature at the top of the distillation column is above the azeotropic point of the mixture of the azeotropic agent and the water. The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the temperature at the bottom of the distillation column is the boiling point of the mixture discharged to the bottom of the distillation column.

9. When the azeotrope is isopropyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm². ２ G or -0.925 kg / cm² ２ It is also G, When the azeotrope is ethyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm². ２ G or -0.89 kg / cm ２ It is also G, When the azeotrope is n-propyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm². ２ G or -0.96 kg / cm³ ２ A method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that it is G.

10. The temperature at the point where the liquid from the reactor flows into the distillation column is: The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the upper pressure of the distillation column is at atmospheric pressure and the temperature is 90°C to 140°C.

11. The method for separating water from a mixture of PGME, PGMEA, and water according to claim 1, characterized in that the distillation column includes one or more of trays, random packing, and structured packing.

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