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, and more particularly, to a method for separating water from a mixture of PGME, PGMEA, and water, which can remove water generated as a by-product during the production of PGMEA, which is used as an environmentally friendly solvent, from reactants and reaction products, thereby improving the reaction rate for producing PGMEA and increasing the purity of PGMEA. [Background technology]

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

[0003] Referring to FIG. 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 by-product of the reaction.

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

[0005] The boiling temperatures of the reactants and reaction products at normal pressure are water at about 100° C., acetic acid at about 118° C., PGME at about 120° C., and PGMEA at about 146° C. Here, since the boiling temperature of water is the lowest at about 100° C., it seems possible to separate water by evaporating it through distillation, but at normal pressure, water-PGME and water-PGMEA form an azeotrope at about 96° C. to 98° C.

[0006] That is, water-PGME and water-PGMEA form an azeotropic mixture with water at a temperature lower than the boiling point of water and evaporate together. In such a reaction, the reactants PGME and water are evaporated and discharged in a weight ratio of about 52:48, which causes a problem that the PGME required for the reaction must be added and replenished. The generated PGMEA is also discharged together with water in an azeotropic mixture in a weight ratio of about 56:44, which causes a problem of low reaction yield.

[0007] In order to solve such problems, a method has been used in which toluene, which forms an azeotropic mixture with water at a temperature lower than the azeotropic temperature of water·PGME and water·PGMEA, is used as an entrainer to remove water.

[0008] However, when toluene is used as an azeotropic agent, the azeotropic point of water-toluene at normal pressure is about 84.3°C, but the azeotropic point of the three components of water-PGME-toluene at normal pressure is lower, at about 83.9°C. This causes problems in that PGME and water form an azeotrope first with toluene at a weight ratio of about 0.76:1, and PGME, which is a reactant, is lost in large amounts as wastewater due to the water-soluble solvent.

[0009] In addition to the method of using toluene as an azeotropic agent, a method of using cyclohexane as an azeotropic agent to remove water has also been used in the past.

[0010] However, when cyclohexane is used as an azeotropic agent, the azeotropic point of cyclohexane and water at normal pressure is about 69.5°C, but the azeotropic point of the three components water, PGME, and cyclohexane at normal pressure is lower, at about 69°C. As a result, there is a problem that PGME and water first form an azeotrope with cyclohexane in a weight ratio of about 1:1, and PGME, which is a reactant, is lost in large amounts as wastewater due to water-soluble solvents.

[0011] In addition, methods using various azeotropic agents have been disclosed in the past, but the proposed azeotropic agents form azeotropes with PGME or PGMEA, so there is a problem that the loss of PGME or PGMEA must be tolerated (U.S. Patent Publication US4,544,453).

[0012] Conventionally, PGME has been extracted from water using ethyl benzyl ether as an extractant, but since PGME is water-soluble, it cannot be completely extracted from water, resulting in loss of PGME.

[0013] There are also methods that use pervaporation to recover PGME and PGMEA mixed with water, but such methods are not suitable for commercial application because they require a very large area pervaporation membrane. Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention is intended to solve the above problems, and more particularly, relates to a method for separating water from a mixture of PGME, PGMEA and water, which can remove water generated as a by-product during the preparation of PGMEA, which is used as an environmentally friendly solvent, from reactants and reaction products, thereby improving the reaction rate for the preparation of PGMEA and increasing the purity of PGMEA. [Means for solving the problem]

[0015] In order to solve the above-mentioned problems, the method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA) and water according to the present invention includes a reactor inflow step of inflowing PGME and acetic acid into a reactor, a distillation column inflow step of inflowing the liquid of the reactor into a distillation column, an entrainer inflow step of inflowing an entrainer into the upper part of the distillation column, and a condensation step of condensing the mixture of water and the entrainer evaporated from the upper part of the distillation column in a condenser.

[0016] In order to solve the above-mentioned problems, the azeotropic agent in the method for separating water from a mixture of PGME, PGMEA and water according to the present invention contains at least one of isopropyl acetate, ethyl acetate and n-propyl acetate.

[0017] In order to solve the above problems, the method for separating water from a mixture of PGME, PGMEA and water according to the present invention further includes a reflux step of separating the liquid phase condensed in the condenser into an organic layer and an aqueous layer in a flow separator and refluxing the organic layer to the distillation column, and a discharge step of separating the liquid phase condensed in the condenser into an organic layer and an aqueous layer in a flow separator and discharge the aqueous layer.

[0018] In the method for separating water from a mixture of PGME, PGMEA and water according to the present invention for solving the above problems, the catalyst for promoting the reaction between PGME and acetic acid may be mixed with the liquid flowing into the reactor and the distillation column.

[0019] In order to solve the above-mentioned problems, the catalyst of the method for separating water from a mixture of PGME, PGMEA and water of the present invention is made of a material having a boiling temperature of 220°C or higher at normal pressure, or a boiling temperature of 140°C or higher at 20 mmHg.

[0020] In the method for separating water from a mixture of PGME, PGMEA and water according to the present invention for solving the above problems, the solid catalyst promoting the reaction between PGME and acetic acid is packed in the distillation column, and the solid catalyst may be packed below an inlet point where the liquid from the reactor flows into the distillation column.

[0021] In order to solve the above problems, the method for separating water from a mixture of PGME, PGMEA and water according to the present invention further includes a reintroduction step of reintroducing the liquid discharged from the bottom of the distillation column into the reactor.

[0022] In order to solve the above-mentioned problems, in the method for separating water from a mixture of PGME, PGMEA and water according to the present invention, the number of separation plates in the distillation column is 21 or more.

[0023] In the method for separating water from a mixture of PGME, PGMEA and water according to the present invention for solving the above problems, the inlet point where the liquid from the reactor is introduced into the distillation tower is a point spaced apart by about 8 separation plates from the top of the distillation tower, or is lower than a point spaced apart by about 8 separation plates from the top of the distillation tower.

[0024] In the method for separating water from a mixture of PGME, PGMEA and water according to the present invention for solving the above-mentioned problems, the inflow point where the liquid from the reactor flows into the distillation tower is a point that is separated by about two separation plates from the bottom of the distillation tower, or is above a point that is separated by about two separation plates from the bottom of the distillation tower.

[0025] In order to solve the above problems, the reactor and the distillation column of the method for separating water from a mixture of PGME, PGMEA and water of the present invention can be integrally formed.

[0026] In the method for separating water from a mixture of PGME, PGMEA and water according to the present invention for solving the above-mentioned problems, the temperature of the upper part of the distillation column is equal to or higher than the azeotropic point of the mixture of the entrainer and the water, and the temperature of the lower part of the distillation column is also the boiling point of the mixture discharged to the lower part of the distillation column.

[0027] In the method for separating water from a mixture of PGME, PGMEA and water according to the present invention for solving the above problems, when the azeotropic agent is isopropyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm 2 G or -0.925kg / cm 2 When the azeotropic agent is ethyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm 2 G or -0.89kg / cm 2 When the azeotropic agent is n-propyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm 2 G or -0.96kg / cm 2 It's also G.

[0028] In the method for separating water from a mixture of PGME, PGMEA and water according to the present invention for solving the above problems, the temperature of the liquid from the reactor at the inlet point where it is introduced into the distillation column is 90°C to 140°C when the pressure at the top of the distillation column is normal pressure.

[0029] In order to solve the above-mentioned problems, the distillation column of the method for separating water from a mixture of PGME, PGMEA and water of the present invention also includes at least one of trays, random packing and structured packing. Effect 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, and has an advantage in that water generated as a by-product during the production of PGMEA, which is used as an environmentally friendly solvent, can be removed from reactants and reaction products, thereby improving the reaction rate of PGMEA production.

[0031] In addition, the present invention has an advantage that the purity of PGMEA can be increased by removing water, which is generated as a by-product during the preparation of PGMEA, which is used as an environmentally friendly solvent, from reactants and reaction products.

[0032] In addition, the present invention has an advantage that the loss of reactants and reaction products can be minimized by removing water generated as a by-product from reactants and reaction products during the preparation of PGMEA used as an environmentally friendly solvent, thereby making it possible to economically produce PGMEA, an environmentally friendly solvent used as a paint solvent, electronic material solvent, etc. [Brief description of the drawings]

[0033] [Figure 1] FIG. 1 is a diagram showing a reaction formula for producing propylene glycol monomethyl ether acetate (PGMEA) by reacting propylene glycol monomethyl ether (PGME) with acetic acid in the presence of a catalyst. [Diagram 2] 1 is a flow chart of a method for separating water from a mixture of PGME, PGMEA, and water, according to an embodiment of the present invention. [Diagram 3]FIG. 1 shows a reactor and distillation column for separating water from a mixture of PGME, PGMEA, and water in accordance with an embodiment of the present invention. [Figure 4] FIG. 1 shows a reactor and distillation column for separating water from a mixture of PGME, PGMEA, and water in accordance with an embodiment of the present invention. [Diagram 5] FIG. 2 shows an integrated reactor and distillation column for separating water from a mixture of PGME, PGMEA, and water, according to an embodiment of the invention. [Figure 6] FIG. 2 shows an integrated reactor and distillation column for separating water from a mixture of PGME, PGMEA, and water, according to an embodiment of the invention. [Figure 7] FIG. 2 is a composition distribution diagram inside a distillation column when isopropyl acetate is used as an azeotropic agent according to one embodiment of the present invention. [Figure 8] FIG. 2 is a composition distribution diagram inside a distillation column when ethyl acetate is used as an azeotropic agent according to another embodiment of the present invention. [Figure 9] FIG. 2 is a composition distribution diagram inside a distillation column when normal propyl acetate is used as an azeotropic agent according to yet another embodiment of the present invention. [Figure 10] FIG. 2 is a composition distribution diagram inside a distillation column when toluene is used as an azeotropic agent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] The present specification explains the principles of the present invention and discloses embodiments so as to clarify the scope of the present invention and enable those skilled in the art to practice the present invention. The disclosed embodiments may be embodied in various forms.

[0035] The terms "comprise" or "also include" as used in the various embodiments of the present invention indicate the presence of the disclosed feature, operation, component, etc., but do not limit the presence of one or more additional features, operations, components, etc. Also, in the various embodiments of the present invention, the terms "comprise" or "have" as specifying the presence of a specified feature, number, steps, operations, components, parts, or combinations thereof, and should not be understood as precluding the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0036] When a component is referred to as being "connected" or "coupled" to another component, it should be understood that the component may be directly connected or coupled to the other component, but that there may be additional components between the component and the other component. On the other hand, when a component is referred to as being "directly connected" or "directly coupled" to another component, it should be understood that there are no additional components between the component and the other component.

[0037] As used herein, terms such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another. Temperatures according to embodiments of the present invention are also in 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, and more particularly, to a method for separating water from a mixture of PGME, PGMEA, and water, which can remove water generated as a by-product during the manufacture of PGMEA, which is used as an environmentally friendly solvent, from reactants and reaction products, thereby improving the reaction rate of PGMEA manufacture and increasing the purity of PGMEA. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0039] A method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention uses an entrainer 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 entrainer, thereby preventing acetic acid, PGME, and PGMEA from being washed away by azeotropy at a temperature lower than the azeotropic temperature of water and the entrainer.

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

[0041] 2 and 3, the reactor inflow step (S110) is a step of inflowing PGME and acetic acid into the reactor 110. According to an embodiment of the present invention, as shown in Fig. 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 by-product.

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

[0043] The azeotropic agent introduction step (S130) is a step of introducing an azeotropic agent into the upper part of the distillation column 120. The azeotropic agent may be used to introduce the liquid of 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 of condensing the mixture of water and the azeotropic agent evaporated from the upper part of the distillation column 120 in a condenser 130. The mixture of water and the azeotropic agent evaporated from the upper part of the distillation column 120 may be condensed in the condenser 130 and then transferred to a water separator 131.

[0045] According to an embodiment of the present invention, the azeotropic agent may include one or more of isopropyl acetate, ethyl acetate, and n-propyl acetate.

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

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

[0048] n-Propyl acetate can be used as an azeotropic agent because it forms an azeotrope with water at a weight ratio of about 5.3:1 at about 83° C. under normal pressure, does not form an azeotrope with acetic acid, PGME, or PGMEA, and does not form a ternary azeotrope with water.

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

[0050] For this reason, the number of separation stages of the distillation tower 120 according to an embodiment of the present invention may be 21 or more, and the inlet point where the liquid of the reactor 110 flows into the distillation tower 120 may be a point that is separated by about 8 separation stages from the top of the distillation tower 120, or may be lower than a point that is separated by about 8 separation stages from the top of the distillation tower 120.

[0051] If the number of separation plates of the distillation column 120 is less than 21, acetic acid, PGME, and PGMEA are likely to flow out to the upper part of the distillation column 120, and the entrainer ethyl acetate or isopropyl acetate flows out to the lower part of the distillation column 120 and comes into contact with PGME in the presence of a catalyst, causing a side reaction and forming impurities.

[0052] Therefore, in order to prevent acetic acid, PGME, and PGMEA from flowing out to the top of the distillation column 120, or to prevent the entrainer ethyl acetate or isopropyl acetate from flowing out to the bottom of the distillation column 120 and coming into contact with PGME in the presence of a catalyst, it is preferable that the number of separation plates in the distillation column 120 is 21 or more.

[0053] However, if the number of separation stages of the distillation tower 120 is too large, the effect is not large compared to the construction cost of the distillation tower 120. Therefore, the number of separation stages of the distillation tower 120 is preferably 120 or less.

[0054] Here, the distillation tower 120 may form a number of separation stages while being separated by trays installed inside the distillation tower 120, and the number of separation stages of the distillation tower 120 may be determined depending on the number of the trays.

[0055] The number of separation stages in the distillation tower 120 is not the theoretical number of stages, but also the actual number of stages constituting the distillation tower. In addition, the degree of separation of materials in the distillation tower 120 is related to the number of separation stages, and the tray spacing is only related to the processing capacity, so the separation stage spacing may be configured to be 300 mm to 950 mm, which is the commonly used separation stage spacing.

[0056] Generally, to process the same volume, if the separation tray spacing is narrower, the diameter of the distillation column will be larger than if the separation tray spacing is wider, and the tray thickness is generally 2 mm to 6 mm.

[0057] However, since the thickness of the tray is determined by the diameter of the distillation column and the mechanical strength of the tray, the thickness of the tray does not affect the separation of the substances in the distillation column, and therefore the thickness of the tray is not limited to 2 mm to 6 mm, and may be variously changed.

[0058] According to an embodiment of the present invention, the distillation column 120 may include at least one of a tray, a random packing, and a structured packing. The separation stage of the distillation column 120 may be a tray such as a bubble cap tray, a perforated tray, or a valve tray, and the separation stage of the distillation column 120 may be at least one of a structured packing and a random packing.

[0059] However, the present invention is not limited thereto, and the separation stages of the distillation column 120 according to an embodiment of the present invention may be configured by mixing trays, random packing, structured packing, 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 stages or more and 120 stages or less.

[0061] The number of stages of the structured packing or random packing can be converted into the number of trays by calculation using literature 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) information provided by the manufacturer.

[0062] According to one embodiment, the structured packing is characterized in terms of surface area per unit volume, and the surface area of ​​the structured packing used in the distillation column is between 125 and 1,000 m 2 / m 3 In this case, the height of the packed 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 3In the case where the distillation column 120 is constructed with a structured packing having a packing bed height of 2.1 m, 21 separation stages can be constructed. Alternatively, the distillation column 120 can be constructed with a structured packing having a surface area per unit volume of 1,000 m. 2 / m 3 If a structured packing with a height of 1 m is used and 11 trays are used, a total of 21 separation stages can be configured.

[0064] By using such a method, the number of stages of the structured packing can be converted into the number of tray stages. The method of converting the number of stages of the structured packing or the random packing into the number of tray stages is a known technique, and therefore detailed description thereof will be omitted.

[0065] According to an embodiment of the present invention, the inlet point of the liquid from the reactor 110 into the distillation tower 120 is preferably a point spaced apart by about 8 separation stages from the top of the distillation tower 120, or a point below a point spaced apart by about 8 separation stages from the top of the distillation tower 120.

[0066] If the inlet point of the liquid from the reactor 110 into the distillation tower 120 is not separated by 8 separation plates from the top of the distillation tower 120, and the liquid from the reactor 110 is introduced from an upper portion of the distillation tower 120 that is separated by 8 separation plates from the top of the distillation tower 120, the entrainers ethyl acetate, isopropyl acetate, and n-propyl acetate will mix with PGME in the presence of a catalyst, causing transesterification of PGME.

[0067] Specifically, since the distance between the point where the liquid of the reactor 110 flows in and the azeotropic agent flowing into the upper part of the distillation column 120 becomes short, the azeotropic agent mixes with PGME in the presence of a catalyst, which causes 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 preferable that the inlet point of the liquid from the reactor 110 into the distillation tower 120 is a point that is about 8 separation stages away from the top of the distillation tower 120, or is lower than a point that is about 8 separation stages away from the top of the distillation tower 120.

[0069] According to one embodiment, when the distillation tower 120 has 21 stages, the inlet point where the liquid from the reactor 110 flows into the distillation tower 120 is at stage 8, which is about 8 separation stages away from the top of the distillation tower 120, or it is lower than stage 8.

[0070] Here, the azeotropic agent flowing into the upper part of the distillation column 120 may be flowed through the top stage of the distillation column 120 or a stage immediately below the top stage, but is not limited thereto.

[0071] In addition, according to an embodiment of the present invention, the inlet point of the liquid from the reactor 110 into the distillation tower 120 is preferably a point that is separated by about two separation stages from the bottom of the distillation tower 120, or is above a point that is separated by about two separation stages from the bottom of the distillation tower 120.

[0072] However, this is not limited thereto, and when the distillation tower 120 has a large number of separation stages, the inlet point where the liquid from the reactor 110 flows into the distillation tower 120 may be changed as necessary.

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

[0074] 2 and 3, the reflux step (S141) is a step of separating the liquid phase condensed in the condenser 130 into an organic layer and an aqueous layer in the flow separator 131, and refluxing the organic layer to the distillation column 120. The discharge step (S142) is a step of separating the liquid phase condensed in the condenser 130 into an organic layer and an aqueous layer in the flow separator 131, and discharging the aqueous layer.

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

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

[0077] The reflux step (S141) is for refluxing the organic layer separated through the water separator 131 to the distillation column 120, and the entrainer contained in the organic layer can be further introduced into the distillation column 120 through the reflux step (S141).

[0078] The discharge step (S142) is for discharging the aqueous layer separated through the flow-through separator 131, and in the discharge step (S142), the aqueous layer separated through the flow-through separator 131 may be discharged to the outside.

[0079] However, this is not limited thereto, and in order to suppress the discharge of acetic acid, PGME, and PGMEA to the top of the distillation column 120, a portion of the water discharged from the water layer of the water separator 131 can be refluxed to the distillation column 120.

[0080] Here, the organic layer and the aqueous layer containing the entrainer to be refluxed to the distillation column 120 are preferably refluxed to the top of the distillation column 120. However, in consideration of ease of operation of the distillation column 120, the organic layer and the aqueous layer may be partially refluxed to the middle of the distillation column 120.

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

[0082] The method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention also further includes a re-entry step (S150).

[0083] 2 and 3, the re-introduction step (S150) is a step of re-introducing the liquid discharged to the bottom of the distillation tower 120 into the reactor 110. If water is separated through the distillation tower 120, water can be separated from the liquid discharged to the bottom of the distillation tower 120.

[0084] The re-introduction step (S150) is a step of re-introducing the liquid at the bottom of the distillation tower 120, from which water has been separated, into the reactor 110. The liquid at the bottom of the distillation tower 120 is also acetic acid, PGME, PGMEA, and a catalyst. The liquid at the bottom of the distillation tower 120 is continuously circulated between the reactor 110 and the distillation tower 120, and in this process, PGME reacts with acetic acid and is converted into PGMEA. After the reaction is completed, PGMEA can be discharged from the reactor 110.

[0085] In the re-inflow step (S150), after the liquid in the lower part of the distillation tower 120 is re-inflowed into the reactor 110, while the liquid in the lower part of the distillation tower 120 is circulated between the reactor 110 and the distillation tower 120, a reaction of acetic acid, PGME, and a catalyst to produce PGMEA and water continues, and the water produced in the reaction can be removed from the distillation tower 120.

[0086] Referring to FIG. 4, a small amount of gas may be generated in the reactor 110 due to a temperature increase in the reactor 110 , and the gas generated in the reactor 110 may flow into the distillation column 120 .

[0087] 5, the reactor 110 and the distillation tower 120 according to the embodiment of the present invention may be integrated. The reactor 110 may be installed below the distillation tower 120, and the reactor 110 and the distillation tower 120 may be integrated.

[0088] When the reactor 110 and the distillation column 120 are integrally configured, the installation space of the apparatus can be reduced, and the liquid at the bottom of the distillation column 120 is re-flowed into the reactor 110 through a downcomer 123 of a collector tray 122 installed at the bottom of the distillation column 120, so that there is an advantage that a separate liquid transfer device is not required.

[0089] At this time, the distillation column 120 is provided with a reboiler 121, and the liquid can be reheated through the reboiler 121. Also, referring to FIG. 6, the reboiler 121 may be provided in the reactor 110.

[0090] According to an embodiment of the present invention, a catalyst for promoting the reaction of the PGME and the acetic acid may be mixed with the liquid flowing into the reactor 110 and into the distillation column 120.

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

[0092] If the boiling temperature of the catalyst is lower than 220° C., the catalyst may boil up to the upper part of the inlet point of the distillation column 120 and may be mixed with the azeotropic agent to cause the transesterification reaction of PGME. Therefore, the catalyst flowing into the reactor 110 is preferably a material having a boiling temperature of 220° C. or higher at atmospheric pressure.

[0093] Here, when measuring the boiling point of the catalyst, if the temperature is raised to 220°C under normal pressure, the catalyst may be decomposed and the boiling temperature may not be measured. Therefore, the boiling temperature of the catalyst is measured under temperature conditions where the catalyst is not decomposed, and therefore the catalyst may be a material having a boiling temperature of 140°C or higher at 20 mmHg.

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

[0095] According to an embodiment of the present invention, the catalyst may be a solid catalyst, which is not dissolved by the reactants. When the catalyst is a solid catalyst which is not dissolved by the reactants, the solid catalyst may be filled at a lower part of the inlet point where the liquid of the reactor 110 flows into the distillation column 120.

[0096] The solid catalyst is packed below the inlet point where the liquid of the reactor 110 flows into the distillation tower 120, so that the distillation tower 120 can function as both the reactor 110 and the distillation tower 120 at the same time.

[0097] In this case, the conditions for preventing the entrainer from contacting with PGME in the presence of the catalyst are the same as those described above, and the operating conditions are the same as those described below. The method for packing the solid catalyst in the distillation column 120 may be to pack the solid catalyst in a section separate from the separation stage, or to pack the solid catalyst by adhering it to trays, random packing, structured packing, etc.

[0098] However, the present invention is not limited thereto, and the catalyst may also be flowed into the reactor 110, and the catalyst may be flowed into and packed in at least one of the reactor 110 and the distillation column 120.

[0099] According to an embodiment of the present invention, the temperature of the upper part of the distillation column 120 is equal to or higher than the azeotropic point of the mixture of the azeotropic agent and the water, and the temperature of the lower part of the distillation column 120 is equal to or higher than the boiling point of the mixture discharged to the lower part of the distillation column 120.

[0100] The temperature of the upper part of the distillation tower 120 must be set to a temperature equal to or higher than the azeotropic point of the mixture of the azeotropic agent and the water in order to evaporate the mixture of the azeotropic agent and the water and separate the water. Therefore, the temperature of the upper part of the distillation tower 120 can be determined based on the azeotropic point of the mixture of the azeotropic agent and the water. In addition, the temperature of the lower part of the distillation tower 120 is also the boiling point of the mixture (PGMEA, catalyst, etc.) discharged to the lower part of the distillation tower 120.

[0101] According to an embodiment of the present invention, when the azeotropic agent is isopropyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm 2 G or -0.925kg / cm 2 When the azeotropic agent is ethyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm 2 G or -0.89kg / cm 2 When the azeotropic agent is normal propyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm 2 G or -0.96kg / cm 2 It's also G.

[0102] The azeotropic agent is isopropyl acetate, and the pressure at the top of the distillation column 120 is 0.5 kg / cm 2 G or -0.925kg / cm 2 When the temperature is G, the temperature of the upper part of the distillation column 120 may be adjusted to about 88°C to about 25°C, and the temperature of the lower part of the distillation column 120 may be adjusted to about 160°C to about 82°C.

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

[0104] The pressure at the top of the distillation column 120 is -0.925 kg / cm 2 If the pressure is lower than 0.5 kg / cm, the gas temperature at the top of the distillation column 120 will be below 25° C., and a refrigerator will have to be used to condense the gas, resulting in an uneconomical process configuration. Therefore, when the azeotropic agent is isopropyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm 2 G or -0.925kg / cm 2 Preferably G.

[0105] The azeotropic agent is ethyl acetate, and the pressure at the top of the distillation column 120 is 0.5 kg / cm 2 G or -0.89kg / cm 2 When the temperature is G, the temperature of the upper part of the distillation column 120 may be adjusted to about 83°C to about 25°C, and the temperature of the lower part of the distillation column 120 may be adjusted to about 160°C to about 88°C.

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

[0107] The pressure at the top of the distillation column 120 is -0.89 kg / cm 2If the pressure is lower than 0.5 kg / cm, the gas temperature at the top of the distillation column 120 will be below 25° C., and a refrigerator will have to be used to condense the gas, which is an uneconomical process configuration. Therefore, when the azeotropic agent is ethyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm. 2 G or -0.89kg / cm 2 Preferably G.

[0108] The azeotropic agent is n-propyl acetate, and the pressure at the top of the distillation column 120 is 0.5 kg / cm 2 G or -0.96kg / cm 2 When the temperature is G, the temperature of the upper part of the distillation column 120 may be adjusted to about 95°C to about 25°C, and the temperature of the lower part of the distillation column 120 may be adjusted to about 160°C to about 73°C.

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

[0110] The pressure at the top of the distillation column 120 is -0.96 kg / cm 2 If the pressure is lower than 0.5 kg / cm, the gas temperature at the top of the distillation column 120 will be 25° C. or lower, and a refrigerator will have to be used to condense the gas, which is an uneconomical process configuration. Therefore, when the azeotropic agent is n-propyl acetate, the pressure at the top of the distillation column 120 is 0.5 kg / cm. 2 G or -0.96kg / cm 2 Preferably G.

[0111] According to an embodiment of the present invention, the temperature of the inlet point of the liquid of the reactor 110 into the distillation tower 120 is 90° C. to 140° C. when the top pressure of the distillation tower 120 is normal pressure, and the top pressure of the distillation tower 120 is −0.625 kg / cm 2 When it is G, it is also 65°C to 115°C.

[0112] If the temperature of the inlet point of the liquid from the reactor 110 to the distillation column 120 is too low, the azeotropic agent flowing into the upper part of the distillation column 120 may reach the inlet point and may come into contact with PGME in the presence of a catalyst, causing a transesterification reaction.

[0113] In addition, if the temperature of the inlet point where the liquid from the reactor 110 flows into the distillation column 120 is excessively high, the catalyst flowing from the reactor 110 may rise to above the inlet point, and the entrainer may come into contact with PGME below the catalyst, causing a transesterification reaction.

[0114] That is, if the temperature of the inlet point where the liquid from the reactor 110 flows into the distillation tower 120 is excessively low or high, the entrainer flowing into the top of the distillation tower 120 will descend, or the catalyst flowing through the reactor 110 will rise to the top of the distillation tower 120, causing the entrainer to come into contact with PGME under the catalyst, resulting in a risk of a transesterification reaction.

[0115] Therefore, the temperature of the inlet point of the liquid of the reactor 110 into the distillation tower 120 is preferably 90° C. to 140° C. when the top pressure of the distillation tower 120 is normal pressure, and the top pressure of the distillation tower 120 is −0.625 kg / cm 2 When the temperature is G, it is preferably 65°C to 115°C.

[0116] However, according to an embodiment of the present invention, the temperature of the inlet point where the liquid from the reactor 110 flows into the distillation tower 120 varies depending on the pressure at the top of the distillation tower 120, and also varies depending on the pressure at the inlet point determined by the pressure drop inside the distillation tower 120 and the liquid composition formed at the inlet point.

[0117] Through the method for separating water from a mixture of PGME, PGMEA, and water according to the embodiment of the present invention, the reactants acetic acid and PGME, and the reaction product PGMEA are not lost through water, and the transesterification reaction of PGME is suppressed, while the water generated during the reaction is continuously removed, thereby improving reactivity.

[0118] In addition, the number of separation stages of the distillation tower 120 is 21, and the inlet point where the liquid of the reactor 110 flows into the distillation tower 120 is located at a point separated by 8 separation stages from the top of the distillation tower 120 or is located below a point separated by 8 separation stages from the top of the distillation tower 120, thereby maintaining the concentration of the entrainer in the liquid phase at the inlet point where the liquid of the reactor 110 flows in at 100 ppm by weight or less.

[0119] In addition, the number of separation stages of the distillation tower 120 is 21, and the inlet point of the liquid of the reactor 110 into the distillation tower 120 is located at a point 8 separation stages away from the top of the distillation tower 120 or at a point lower than a point 8 separation stages away from the top of the distillation tower 120. This allows the concentration of the entrainer in the liquid discharged to the bottom of the distillation tower 120 and flowing into the reactor 110 to be maintained at 10 ppm by weight or less, thereby minimizing the transesterification reaction of PGME.

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

[0121] [Example 1]

[0122] According to an 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 catalyst is introduced from the reactor 110 into the middle point of the distillation column 120, while an azeotropic agent, isopropyl acetate, is introduced into the upper part of the distillation column 120. As the catalyst, p-toluenesulfonic acid (PTSA) having a boiling point of 140° C. at 20 mmHg was used.

[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 pressure at the top of the distillation column 120 was normal pressure while the temperature at the top of the distillation column 120 was about 77°C.

[0124] The temperature at the bottom of the distillation column 120 was 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 about 135°C.

[0125] The temperature of the upper constant separation stage at the inlet point where the liquid from the reactor 110 flows into the distillation column 120 was adjusted to about 97° C. so that the azeotropic agent would not reach the inlet point and the catalyst flowing into the inlet point would not mix with the azeotropic agent.

[0126] The temperature of the liquid flowing from the reactor 110 to the distillation tower 120 was about 60°C to 135°C because the liquid discharged from the bottom of the distillation tower 120 was flowing into the reactor 110 and then flowing back into the distillation tower.

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

[0128] In addition, if the temperature of the liquid flowing from the reactor 110 to the distillation tower 120 is lower than 60°C, the energy used in the reboiler will be excessive. Therefore, it is preferable that the temperature of the liquid flowing from the reactor 110 to the distillation tower 120 is higher than 60°C.

[0129] The temperature at the bottom of the distillation column 120 changes depending on the composition of the liquid discharged from the bottom of the distillation column 120 as the reaction proceeds, so the maximum temperature at the end of the reaction also becomes the boiling temperature of the catalyst and PGMEA.

[0130] That is, according to an embodiment of the present invention, the temperature of the liquid flowing from the reactor 110 to the distillation column 120 is preferably higher than 60° C. and lower than the temperature of the bottom of the distillation column 120 .

[0131] The temperature of the upper stage of the inlet point where the liquid flows from the reactor 110 into the distillation tower 120 is determined depending on which stage is used as a reference, but the temperature is between the temperature of the inlet point and the temperature of the top stage of the distillation tower 120. The temperature of the inlet point is about 113° C. or the boiling point of the liquid composition formed at the inlet point at the pressure, so the temperature of the inlet point can be changed as the reaction proceeds.

[0132] Fig. 7 is a composition distribution diagram in the distillation column 120 when isopropyl acetate is used as an azeotropic agent. Referring to Fig. 7, the concentration of acetic acid, PGME, and PGMEA in the gas discharged to the top of the distillation column 120 is set to 100 ppm by weight or less through the above-mentioned method, and the azeotropic agent is prevented from mixing with PGME in the presence of a catalyst in the distillation column 120, and the azeotropic agent is prevented from flowing out to the bottom of the distillation column 120.

[0133] Specifically, referring to FIG. 7, it can be seen that no PGME or PGMEA flows out of the top of distillation column 120, and no azeotropic agent flows out of the bottom of distillation column 120, and it can be seen that there is no section in distillation column 120 where the azeotropic agent mixes with PGME in the presence of a catalyst (referring to FIG. 7, there is no section in distillation column 120 where the azeotropic agent, catalyst, and PGME are all present).

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

[0135] The pressure at the top of the distillation column 120 is -0.625 kg / cm 2 When operating at 1000° C., the temperature at the top of the distillation tower 120 is adjusted to about 53° C., the temperature at the bottom of the distillation tower 120 is adjusted to about 115° C., and the temperature of the upper fixed separation stage at the inlet point where the liquid flows into the distillation tower 120 from the reactor 110 is adjusted to 71° C., the concentration of PGME and PGMEA in the gas discharged to the top of the distillation tower 120 is less than 100 ppm by weight. Therefore, the distillation tower 120 can be operated such that the azeotropic agent does not mix with PGME in the presence of a catalyst, and the azeotropic agent does not flow out to the bottom of the distillation tower 120.

[0136] [Example 2]

[0137] According to 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 flowed from the reactor 110 into the middle point of the distillation column 120, while ethyl acetate as an azeotropic agent is flowed into the top of the distillation column 120. p-Toluenesulfonic acid (PTSA), which has a boiling point of 140° C. at 20 mmHg, is used as the catalyst.

[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 set to about 72° C. while the pressure at the top of the distillation column 120 was kept at normal pressure.

[0139] The temperature at the bottom of the distillation column 120 was 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 about 135°C.

[0140] The temperature of the upper constant separation stage at the inlet point where the liquid from the reactor 110 flows into the distillation column 120 was adjusted to about 93° C. so that the azeotropic agent would not reach the inlet point and the catalyst flowing into the inlet point would not mix with the azeotropic agent.

[0141] The temperature of the liquid flowing from the reactor 110 to the distillation tower 120 was about 60°C to 135°C because the liquid discharged from the bottom of the distillation tower 120 was flowing into the reactor 110 and then flowing back into the distillation tower.

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

[0143] In addition, if the temperature of the liquid flowing from the reactor 110 to the distillation tower 120 is lower than 60°C, the energy used in the reboiler is excessive, so it is preferable that the temperature of the liquid flowing from the reactor 110 to the distillation tower 120 is higher than 60°C.

[0144] The temperature at the bottom of the distillation column 120 changes depending on the composition of the liquid discharged from the bottom of the distillation column 120 as the reaction proceeds, so the maximum temperature at the end of the reaction also becomes the boiling temperature of the catalyst and PGMEA.

[0145] That is, according to an embodiment of the present invention, the temperature of the liquid flowing from the reactor 110 to the distillation column 120 is preferably higher than 60° C. and lower than the temperature of the bottom of the distillation column 120 .

[0146] The temperature of the upper stage of the inlet point where the liquid flows from the reactor 110 into the distillation tower 120 is determined depending on which stage is used as a reference, and the temperature is between the temperature of the inlet point and the temperature of the top stage of the distillation tower 120. The temperature of the inlet point is about 108° C., or the boiling point of the liquid composition formed at the inlet point at the pressure, so the temperature of the inlet point can be changed as the reaction proceeds.

[0147] Fig. 8 is a composition distribution diagram in the distillation column 120 when ethyl acetate is used as an azeotropic agent. Referring to Fig. 8, the concentration of acetic acid, PGME, and PGMEA in the gas discharged to the top of the distillation column 120 is set to 100 ppm by weight or less through the above-mentioned method, and the azeotropic agent is prevented from being mixed with PGME in the presence of a catalyst in the distillation column 120, and the azeotropic agent is prevented from being discharged to the bottom of the distillation column 120.

[0148] Specifically, referring to FIG. 8, it can be seen that no PGME or PGMEA flows out of the top of distillation column 120, and no azeotropic agent flows out of the bottom of distillation column 120, and it can be seen that there is no section in distillation column 120 where the azeotropic agent is mixed with PGME in the presence of a catalyst (referring to FIG. 8, there is no section in distillation column 120 where the azeotropic agent, catalyst, and PGME are all present).

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

[0150] The pressure at the top of the distillation column 120 is -0.625 kg / cm 2 When the distillation tower 120 is operated at a temperature of about 48° C., the temperature at the top of the distillation tower 120 is adjusted to about 115° C., and the temperature of the upper fixed separation stage at the inlet point where the liquid from the reactor 110 flows into the distillation tower 120 is adjusted to 52° C., the concentration of PGME and PGMEA in the gas discharged to the top of the distillation tower 120 is 100 ppm by weight or less, and the distillation tower 120 can be operated such that the entrainer is not mixed with PGME in the presence of a catalyst, and the entrainer is not discharged to the bottom of the distillation tower 120.

[0151] [Embodiment 3]

[0152] According to one 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 catalyst is introduced from the reactor 110 into the middle point of the distillation column 120, while n-propyl acetate as an azeotropic agent is introduced into the upper part of the distillation column 120. p-Toluenesulfonic acid (PTSA), which has a boiling point of 140° C. at 20 mmHg, is used as the catalyst.

[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 set to about 83° C. while the pressure at the top of the distillation column 120 was kept at normal pressure.

[0154] The temperature at the bottom of the distillation column 120 was 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 about 135°C.

[0155] The temperature of the upper constant separation stage at the inlet point where the liquid from the reactor 110 flows into the distillation column 120 was adjusted to about 116° C. so that the azeotropic agent would not reach the inlet point and the catalyst flowing into the inlet point would not be mixed with the azeotropic agent.

[0156] The temperature of the liquid flowing from the reactor 110 to the distillation tower 120 was about 60°C to 135°C because the liquid discharged from the bottom of the distillation tower 120 was flowing into the reactor 110 and then flowing back into the distillation tower.

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

[0158] In addition, if the temperature of the liquid flowing from the reactor 110 to the distillation tower 120 is lower than 60°C, the energy used in the reboiler is excessive, so it is preferable that the temperature of the liquid flowing from the reactor 110 to the distillation tower 120 is higher than 60°C.

[0159] The temperature at the bottom of the distillation column 120 changes depending on the composition of the liquid discharged from the bottom of the distillation column 120 as the reaction proceeds, so the maximum temperature at the end of the reaction also becomes the boiling temperature of the catalyst and PGMEA.

[0160] That is, according to an embodiment of the present invention, the temperature of the liquid flowing from the reactor 110 to the distillation column 120 is preferably higher than 60° C. and lower than the temperature of the bottom of the distillation column 120 .

[0161] The temperature of the upper stage of the inlet point where the liquid flows from the reactor 110 into the distillation tower 120 is determined depending on which stage is used as a reference, and the temperature is between the temperature of the inlet point and the temperature of the top stage of the distillation tower 120. The temperature of the inlet point is about 127° C., or the boiling point of the liquid composition formed at the inlet point at the pressure, so the temperature of the inlet point can be changed as the reaction proceeds.

[0162] Fig. 9 is a composition distribution diagram in the distillation column 120 when n-propyl acetate is used as an azeotropic agent. Referring to Fig. 9, the concentration of acetic acid, PGME, and PGMEA in the gas discharged to the top of the distillation column 120 is set to 100 ppm by weight or less through the above-mentioned method, and the azeotropic agent is prevented from being mixed with PGME in the presence of a catalyst in the distillation column 120, and the azeotropic agent is prevented from being discharged to the bottom of the distillation column 120.

[0163] Specifically, referring to FIG. 9, it can be seen that since there is no PGME or PGMEA flowing out to the top of distillation column 120, no azeotropic agent flows out to the bottom of distillation column 120, and it can be seen that there is no section in distillation column 120 where the azeotropic agent mixes with PGME in the presence of a catalyst (referring to FIG. 9, there is no section in distillation column 120 where the azeotropic agent, catalyst, and PGME are all present).

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

[0165] The pressure at the top of the distillation column 120 is -0.625 kg / cm 2 When the distillation tower 120 is operated at a temperature of about 60° C., the temperature at the top of the distillation tower 120 is adjusted to about 116° C., and the temperature of the upper fixed separation stage at the inlet point where the liquid flows into the distillation tower 120 from the reactor 110 is adjusted to 90° C., the concentration of PGME and PGMEA in the gas discharged to the top of the distillation tower 120 is 100 ppm by weight or less, and the distillation tower 120 can be operated such that the azeotropic agent is not mixed with PGME in the presence of a catalyst, and the azeotropic agent is not discharged to the bottom of the distillation tower 120.

[0166] According to an embodiment of the present invention, isopropyl acetate, ethyl acetate, and n-propyl acetate may be partially converted to isopropyl alcohol, ethyl alcohol, and n-propyl alcohol, respectively. The alcohols form an azeotrope with water and may be discharged to the top of the distillation column.

[0167] The alcohol can be removed in a certain amount by transferring the water layer of the water separator to a separate distillation column and distilling or extracting it. The alcohol that is not removed can be refluxed to the distillation column together with the azeotropic agent, but since it forms an azeotrope with water together with the azeotropic agent, it can be discharged to the top of the distillation column.

[0168] The alcohol mixed with the azeotropic agent in the organic layer of the water separator can be removed in a certain amount in a separate distillation column. At normal pressure, isopropyl acetate and isopropyl alcohol, ethyl acetate and ethyl alcohol, and normal propyl acetate and normal propyl alcohol each form an azeotrope, so the separate distillation column is operated at a high pressure to lower the composition of the azeotropic alcohol and remove a certain amount.

[0169] [Comparative Example]

[0170] In a comparative example, a distillation column was constructed with 21 separation stages, and a mixture of water, acetic acid, PGME, PGMEA, and a catalyst was flowed from a reactor into the middle point of the distillation column, while toluene was used as an azeotropic agent and flowed into the top of the distillation column. The pressure at the top of the distillation column was -0.625 kg / cm 2 When operating at G, the temperature at the top of the distillation column was 62°C and the temperature at the bottom of the distillation column was 115°C.

[0171] Figure 10 shows the composition distribution inside the distillation column when toluene is used as an azeotropic agent. Referring to Figure 10, when toluene is used as an azeotropic agent, 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 about 14% by weight, and 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, and since PGME is a water-soluble solvent, a large amount of it is contained in the water layer in the liquid phase in which PGME is condensed and is lost. When toluene is used as an azeotropic agent, it is not possible to prevent PGME from leaking out to the top of the distillation column, no matter how the top temperature at the point where the liquid flows from the reactor into the distillation column is adjusted.

[0173] That is, when isopropyl acetate, ethyl acetate, or n-propyl acetate is used as the azeotropic agent as in the embodiment of the present invention, PGME and PGMEA are prevented from flowing out to the top of the distillation column 120, and the azeotropic agent is prevented from flowing out to the bottom of the distillation column 120, and thus a section in the distillation column 120 in which the azeotropic agent is mixed with PGME in the presence of a catalyst can be eliminated. However, when an azeotropic agent such as toluene which forms an azeotrope with PGME or an azeotropic agent which forms an azeotrope with PGMEA is used as in the comparative example, there is a problem in that it is difficult to prevent PGME and PGMEA from flowing out to the top of the distillation column.

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

[0175] The method for separating water from a mixture of PGME, PGMEA and water according to the above-mentioned embodiment of the present invention has the following advantages:

[0176] The method for separating water from a mixture of PGME, PGMEA and water according to an embodiment of the present invention has an advantage that water generated as a by-product during the production of PGMEA, which is used as an environmentally friendly solvent, can be removed from reactants and reaction products, thereby improving the reaction rate of PGMEA production.

[0177] In addition, the method for separating water from a mixture of PGME, PGMEA and water according to an embodiment of the present invention has an advantage that the purity of PGMEA can be increased by removing water, which is generated as a by-product during the production of PGMEA used as an environmentally friendly solvent, from reactants and reaction products.

[0178] In addition, the method for separating water from a mixture of PGME, PGMEA, and water according to an embodiment of the present invention has the advantage that the loss of reactants and reaction products can be minimized by removing water generated as a by-product from reactants and reaction products during the production of PGMEA used as an environmentally friendly solvent, thereby economically producing PGMEA, an environmentally friendly solvent used as a paint solvent, electronic material solvent, etc.

[0179] As described above, the present invention has been described with reference to the embodiment shown in the drawings, but these are merely illustrative, and those skilled in the art will understand that various modifications and variations of the embodiment are possible therefrom. Therefore, the true technical scope of the present invention is defined by the technical ideas of the appended claims.

Claims

1. A method for separating water from a mixture of propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and water, comprising: A reactor inflow stage in which PGME and acetic acid are flowed into a reactor; a distillation column inflow step of inflowing the liquid from the reactor into a distillation column; an entrainer introducing step of introducing an entrainer into an upper portion of the distillation column; a condensation step of condensing the mixture of water and the azeotropic agent evaporated from the top of the distillation column in a condenser.

2. The azeotropic agent is 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, characterized in that the mixture contains at least one of isopropyl acetate, ethyl acetate and n-propyl acetate.

3. a reflux step of separating the liquid phase condensed in the condenser into an organic layer and an aqueous layer in a water separator and refluxing the organic layer to the distillation column; 2. The method of claim 1, further comprising: separating the liquid phase condensed in the condenser into an organic layer and an aqueous layer in a water separator, and discharging the aqueous layer.

4. The catalyst for promoting the reaction between the PGME and the acetic acid is 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, wherein the PGME, PGMEA and water are mixed with the liquid flowing into the reactor and into the distillation column.

5. 5. The method for separating water from a mixture of PGME, PGMEA and water according to claim 4, wherein the catalyst is a material having a boiling temperature of 220° C. or higher at normal pressure or 140° C. or higher at 20 mmHg.

6. A solid catalyst that promotes the reaction between the PGME and the acetic acid is packed in the distillation column; 2. The method of claim 1, wherein the solid catalyst is packed below an inlet point where the liquid of the reactor flows into the distillation column.

7. 2. The method of claim 1, further comprising a reintroducing step of reintroducing the liquid discharged from the bottom of the distillation column into the reactor.

8. 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, wherein the number of separation plates in the distillation column is 21 or more.

9. The inlet point where the liquid from the reactor is introduced into the distillation column is 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, wherein the distillation column is at a point separated by about 8 separation plates from the top of the distillation column, or at a point below a point separated by about 8 separation plates from the top of the distillation column.

10. The inlet point where the liquid from the reactor is introduced into the distillation column is 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, wherein the separation is performed at a point two separation plates away from the bottom of the distillation column or above a point two separation plates away from the bottom of the distillation column.

11. 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, wherein the reactor and the distillation column are integrated.

12. the temperature at the top of the distillation column is equal to or higher than the azeotropic point of the mixture of the azeotropic agent and the water; 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, wherein the temperature of the bottom of the distillation column is the boiling point of the mixture discharged to the bottom of the distillation column.

13. When the azeotropic agent is isopropyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm ２ G to -0.925 kg / cm ２ It is also G. When the entrainer is ethyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm ２ G -0.89 kg / cm ２ It is also G. When the azeotropic agent is n-propyl acetate, the pressure at the top of the distillation column is 0.5 kg / cm ２ G to -0.96 kg / cm ２ 3. The method for separating water from a mixture of PGME, PGMEA and water according to claim 2, wherein

14. The temperature of the reactor liquid at the inlet point into the distillation column is 2. The method for separating water from a mixture of PGME, PGMEA and water according to claim 1, wherein the distillation column has a top pressure of 90 to 140° C. when the top pressure is normal pressure.

15. 2. The method of claim 1, wherein the distillation column comprises at least one of trays, random packing, and structured packing.

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