Method for preparing isopropanol

Abstract

The present invention provides a method of preparing isopropanol (IPA), which may include: (S1) preparing a crude isopropanol (IPA) product by gas purification and isopropanol purification of a reaction product of propylene and water; (S2) feeding the crude IPA product to a first region of a divided wall column, the divided wall column comprising the first region, a second region, a top region and a bottom region; and (S3) separating water and low-boiling organic materials contained in the crude IPA product into the top region in the divided wall column, separating high-boiling organic materials and inorganic materials contained in the crude IPA product into the bottom region, and obtaining purified isopropanol in a liquid phase or a gas phase in the second region.

Description

Technical Field

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority of Korean Patent Application No. 10-2023→0119579, filed on September 8, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present invention relates to a method for preparing isopropyl alcohol, and more particularly, to a method for purifying high-purity isopropyl alcohol by simultaneously removing organic impurities and inorganic impurities from a crude isopropyl alcohol product. Background Art

[0005] Isopropyl alcohol (IPA) is used for various purposes in the manufacture of electronic industries such as semiconductors, liquid crystal displays (LCDs), etc., including solvents for cleaners, raw materials for industrial paints or reagents, coatings, inks, etc.

[0006] This isopropyl alcohol can be prepared by reacting propylene with water. Generally, for isopropyl alcohol, referring to Figure 1 , propylene monomer is reacted with water in reaction unit 100 to obtain a reaction product containing unreacted propylene monomer, unreacted water, by-products such as n-propanol (NPA) and organic materials, and IPA. The reaction product is transferred to gas purification unit 200 to separate the low-boiling gas components containing unreacted propylene monomer. Then, the reaction product from which the gas components have been separated is fed to IPA purification unit 300 including a plurality of distillation columns to remove organic materials, NPA, and water, thereby obtaining a crude isopropyl alcohol product.

[0007] The crude isopropyl alcohol product obtained through the gas purification unit and IPA purification unit may still contain trace amounts of organic materials and water, and may contain inorganic materials (e.g., metal components of Al, As, Fe, or Mg) present in the reaction water or the reaction catalyst used as a raw material as impurities.

[0008] When used for semiconductor cleaning, the inorganic impurities contained in isopropyl alcohol may cause a decrease in semiconductor yield. Therefore, depending on the type of impurities, the inorganic impurities in the final product need to be controlled at the level of parts per billion (ppb) or parts per trillion (ppt).

[0009] Conventionally, methods have been carried out to remove inorganic materials from the crude isopropyl alcohol product that has undergone a distillation process using a filtration device equipped with a filter or a metal ion adsorption device.

[0010] However, when the content of inorganic materials in the crude isopropyl alcohol product is too high, it may be difficult to simply remove the inorganic materials to the level required in the semiconductor field by applying a filtration device or an adsorption device. Summary of the Invention

[0011] Technical Problem

[0012] In order to solve the problems mentioned in the background art, an object of the present invention is to provide a method for purifying high-purity isopropanol by effectively and simultaneously removing organic materials and inorganic materials remaining in a crude isopropanol product by using a dividing-wall distillation column.

[0013] Technical Solution

[0014] In a general aspect, a method for preparing isopropanol includes:

[0015] (S1) Preparing a crude isopropanol (IPA) product by subjecting a reaction product of propylene and water to gas purification and isopropanol purification;

[0016] (S2) Feeding the crude IPA product to a first region of a dividing-wall distillation column, the dividing-wall distillation column including the first region, a second region, a top region, and a bottom region; and

[0017] (S3) In the dividing-wall distillation column, separating water and low-boiling organic materials contained in the crude IPA product to the top region, separating high-boiling organic materials and inorganic materials contained in the crude IPA product to the bottom region, and obtaining purified isopropanol in a liquid phase or a gas phase in the second region.

[0018] In the method, when the crude IPA product contains inorganic materials of 50 ppb or less based on the total weight of the crude IPA product, liquid-phase purified isopropanol can be obtained in the second region of the dividing-wall distillation column, and when the crude IPA product contains inorganic materials greater than 50 ppb to 100 ppb based on the total weight of the crude IPA product, gas-phase purified isopropanol can be obtained in the second region of the dividing-wall distillation column.

[0019] In the second region of the dividing-wall distillation column, the stage at which the gas-phase purified isopropanol is discharged is lower than the stage at which the liquid-phase purified isopropanol is discharged.

[0020] Advantageous Effects

[0021] According to the present invention, the purification efficiency of IPA can be improved by simultaneously removing organic impurities and inorganic impurities contained in the crude IPA product by applying a dividing-wall distillation column.

[0022] Furthermore, in the present invention, the phase and discharge stage of the final IPA discharged from the dividing-wall distillation column are controlled according to the content level of inorganic materials contained in the crude IPA product, so that the removal efficiency of inorganic materials can be improved while achieving energy conservation.

[0023] That is, when the content of the inorganic material contained in the crude IPA product is 50 ppb or less, the final IPA is discharged in a liquid phase, enabling the residual level of the inorganic material required in the semiconductor field to be satisfied while minimizing energy consumption.

[0024] Meanwhile, when the content of the inorganic material contained in the crude IPA product is greater than 50 ppb, the final IPA is discharged in a gas phase, thereby separating the inorganic material in the form of ions or precipitates, and thus the limitation of removing the inorganic material by the existing filtration device or adsorption device can be overcome. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shows a conventional process for preparing a crude isopropyl alcohol (IPA) product.

[0026] Figure 2 Schematically shows that in one embodiment of the present invention, high-purity purified IPA is obtained in a liquid phase or a gas phase from the crude IPA product by applying a dividing-wall distillation column (dividing-wall column (DWC)). DETAILED DESCRIPTION

[0027] The terms and words used in the specification and claims of the present invention are not to be construed restrictively as having a conventional meaning or the meaning in a dictionary, but are to be understood as having a meaning and concept that satisfy the technical concept of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to describe their own invention in the best way.

[0028] The term "comprising" or "including" used in the present application specifically specifies specific properties, regions, integers, steps, operations, elements, and / or components, but does not exclude the addition of other specific properties, regions, integers, steps, operations, elements, and / or components.

[0029] The term "stream" used in the present application may refer to the flow of a fluid in a process and may also refer to the fluid itself flowing through a pipeline. Specifically, a stream may refer to both the fluid itself flowing through the pipeline connecting each device to each other and the flow of the fluid. In addition, the fluid may include any one or more components of a gas, a liquid, and a solid.

[0030] Unless otherwise specified, the term "top" used in the present application may refer to a point at a height of 0% to 20% from the top to the bottom of the device, that is, the uppermost part. In addition, the term "bottom" may refer to a point at a height of 80% to 100% from the top to the bottom of the device, that is, the lowermost part.

[0031] In addition, the "pressure" mentioned in the present application refers to the gauge pressure measured based on the atmospheric pressure.

[0032] One embodiment of the present invention relates to a method for preparing isopropyl alcohol (IPA). Hereinafter, the method for preparing isopropyl alcohol of the present invention will be described in detail with reference to the accompanying drawings.

[0033] First, a crude isopropyl alcohol (IPA) product is prepared (S1).

[0034] A commercially available crude IPA product can be purchased, or a crude IPA product can be prepared by conventional methods in the art.

[0035] Referring to Figure 1 , propylene monomer is reacted with water in reaction unit 100 to obtain a reaction product containing unreacted propylene monomer, unreacted water, by-products such as n-propanol (NPA) and organic materials, and IPA. Then, the reaction product is transferred to a gas purification unit 200 including an absorption tower, a gas purification tower, etc. to separate the low-boiling gas components including the unreacted propylene monomer. The reaction product (containing IPA, NPA, water and organic materials) from which the gas components have been separated is fed to an IPA purification unit 300, and organic materials, NPA and water are removed through a purification process carried out in a plurality of distillation towers, thereby obtaining a crude isopropyl alcohol product.

[0036] The operating conditions of the gas purification unit and the IPA purification unit can be appropriately selected from the ranges commonly used in the art and are not particularly limited.

[0037] The crude IPA product is obtained by feeding the reaction product of propylene and water to the gas purification unit and the IPA purification unit to separate the gas components and organic materials, but the crude IPA product may still contain trace amounts of organic materials and water. In addition, inorganic materials (e.g., metal components of Al, As, Fe or Mg) present in the reaction water or the reaction catalyst used as a raw material may be contained as impurities.

[0038] For example, based on the total weight of the crude IPA product, the crude IPA product may contain 0.08 wt% or less of water and low-boiling organic materials (e.g., isopropyl ether, acetone, etc.), 0.05 wt% or less of high-boiling organic materials (e.g., n-propanol, hexanol, etc.), and 100 ppb or less of inorganic materials (e.g., metal components of Al, As, Fe, Mg, etc.) as impurities. The types and contents of the impurities contained in the crude IPA product may vary depending on various circumstances involved in the reaction and purification processes.

[0039] In order to simultaneously remove the trace amounts of water, organic materials and inorganic materials contained in the crude IPA product, in the present invention, a dividing wall distillation column (dividing wall column (DWC)) is used to prepare highly purified IPA. The dividing wall distillation column that can be used in the present invention may have a structure commonly used in petrochemical processes and is not particularly limited.

[0040] AsFigure 2 It is schematically shown that the dividing wall distillation column used in the present invention may include a first region 10, a second region 20, a top region 30, and a bottom region 40 which are separated by a dividing wall (DW) inside. The dividing wall DW may be installed at 30% to 70% or 35% to 65% of the total number of stages at the inner center of the distillation column, but is not limited thereto. As an intermediate region including the dividing wall (DW), the first region 10 refers to a preliminary separation region, and the second region 20 refers to a main separation region. At the same time, the top region 30 and the bottom region 40 refer to the uppermost region and the lowermost region of the distillation column that do not include the dividing wall (DW).

[0041] In the first region 10, the second region 20, the top region 30, and the bottom region 40 separated by the dividing wall (DW), a structure in which a perforated plate or a grid-type tray (tray) is installed in multiple stages and a packing bed in which packing is filled in layers with an appropriate height is formed on the perforated plate or the grid-type tray can be used. At each stage of this structure, heat and mass transfer occur as the upward gas flow and the downward liquid flow come into contact with each other, so that a process in which a part of the heavier components condenses and flows to the lower part and the uncondensed vapor continues to rise to the upper end is continuously carried out. There is no particular limitation on the stages and dimensions of the structure, and they can be set based on the theoretical stages inferred from the distillation curve considering the composition of the feed stream. In addition, the dividing wall distillation column may be provided with a reboiler that transfers heat to the stream discharged from the bottom region 40; and a condenser that converts the stream discharged from the top region 30 into a liquid phase.

[0042] In the dividing wall distillation column having such a structure, the crude IPA product prepared in the previous step is added as a feed to the first region 10 (S2) which is a preliminary separation region.

[0043] The first region 10 may include a feed port, which may be located, for example, at the stage corresponding to 30% to 70% or 35% to 65% of the upper end of the first region. In this case, the position of the feed port can be selected considering the type and content of impurities contained in the crude IPA product, the desired purity of the final IPA, the residual amount of impurities, energy consumption, etc.

[0044] In the first region 10, preliminary separation of the crude IPA product can be carried out, and among the separated components, the relatively low-boiling components can be introduced into the top region 30, and the relatively high-boiling components can be introduced into the bottom region 40.

[0045] The second region 20 is the main separation region where additional separation is performed according to the boiling points of the introduced components. And as in the first region 10, among the separated components, the relatively low-boiling components can be introduced into the top region 30, the relatively high-boiling components can be introduced into the bottom region 40, and the intermediate-boiling components can be separated and discharged as the side stream of the second region 20.

[0046] As a result, when the crude IPA product fed to the dividing-wall distillation column undergoes a distillation process through continuous gas-liquid contact in each stage included in the first region 10 for preliminary separation and the second region 20 for main separation, the relatively low-boiling organic materials can rise in the vapor state and can be discharged from the top region 30. The high-boiling organic materials and inorganic materials as relatively heavy components can descend in the condensed state and can be discharged from the bottom region 40, and isopropyl alcohol with the organic materials and inorganic materials separated can be obtained at the side of the second region 20. In addition, the discharge from the top region 30 can contain the trace water contained in the crude IPA product.

[0047] The components discharged from the top region 30 can include water and low-boiling organic materials such as isopropyl ether and acetone, and can pass through a condenser. Then, a part of the components can be discharged, and the remaining part can be refluxed to the top region in the liquid phase.

[0048] To effectively separate these low-boiling organic materials, the top region 30 can be operated at a temperature of 70 °C to 140 °C or 75 °C to 110 °C and a pressure of 0 to 5 kg / cm 2 ·g or 0 to 2 kg / cm 2 ·g.

[0049] The high-boiling organic materials discharged from the bottom region 40 can include n-propanol, hexanol or a mixture thereof. The inorganic materials separated to the bottom region of the dividing-wall distillation column can include one or more metal components selected from Al, As, Fe, and Mg. The discharge from the bottom region 40 can pass through a reboiler. Then, a part of the discharge can be discharged, and the remaining part can be refluxed to the bottom region in the gas phase.

[0050] To effectively separate these high-boiling organic materials and inorganic materials, the bottom region 30 can be operated at a temperature of 75 °C to 150 °C or 80 °C to 120 °C and a pressure of 0 to 6 kg / cm 2 ·g or 0 to 3 kg / cm 2 ·g.

[0051] Thus, when the dividing-wall distillation column is applied, the organic impurities and inorganic impurities contained in the crude IPA product can be removed simultaneously.

[0052] In one embodiment of the present invention, in the second region 20 of the dividing wall distillation column, the side stream, i.e., the discharged phase of purified IPA and the discharge position can be selected according to the composition of the crude IPA product fed to the first region 10.

[0053] When the content of the inorganic materials contained in the crude IPA product is trace, for example, 50 ppb or less, the final purified IPA can be obtained in a liquid phase through the discharge port for the side stream in the second region 20.

[0054] Specifically, the liquid-phase IPA can be obtained by discharging the liquid collected in the collector tray at the stage installed at 20% to 70% or 35% to 65% of the upper end of the second region 20 of the dividing wall distillation column. When the discharge position is satisfied, the separation efficiency of the dividing wall distillation column can be maximized, so that the energy consumption can be minimized and the residual levels of the organic materials and inorganic materials required in the semiconductor field can be satisfied. The energy consumption can be reduced. In addition, the discharged liquid can satisfy the residual level of the inorganic materials required in the semiconductor field because it is the purified product of the feed containing trace inorganic materials.

[0055] When the position for discharging the liquid-phase IPA is higher than 20% of the upper end of the second region 20, the residual amount of the low-boiling organic materials in the final product may increase, and when the position for discharging the liquid-phase IPA is lower than 70% of the upper end of the second region 20, the residual amount of the high-boiling organic materials in the final product may increase.

[0056] Meanwhile, when the content of the inorganic materials contained in the crude IPA product is greater than 50 ppb, the final purified IPA can be obtained in a gas phase through the discharge port for the side stream in the second region 20. Specifically, the gas-phase IPA can be obtained through a nozzle that provides a path for the vapor to rise at the stage located at 40% to 80% or 45% to 75% of the upper end of the second region of the dividing wall distillation column.

[0057] That is, the stage for discharging the gas-phase IPA should be lower than the stage for discharging the liquid-phase IPA. When this is satisfied, the inorganic materials contained in the stream can remain in the liquid in the form of ions or precipitates and can be separated from the IPA discharged in the gas phase, and the presence of the organic impurities in the IPA discharged in the gas phase can be minimized, thus satisfying the level required in the semiconductor field.

[0058] When the position for discharging the gas-phase IPA is higher than 40% of the upper end of the second region 20, the residual amount of the low-boiling organic materials in the gas-phase IPA may increase, and when the position for discharging the gas-phase IPA is lower than 80% of the upper end of the second region 20, the residual amounts of both the organic materials and inorganic materials in the gas-phase IPA may increase.

[0059] In one embodiment of the present invention, in the dividing wall distillation column, the flow rate of the purified IPA in the liquid phase or gas phase discharged through the side stream of the second region 20 may be more than 95% by weight of the total flow rate of the crude IPA product fed to the first region 10.

[0060] In addition, based on the weight of the purified IPA, the residual amount of low-boiling organic materials in the purified IPA in the liquid phase or gas phase is less than 50 ppm, the residual amount of high-boiling organic materials is less than 20 ppm, and the residual amount of inorganic materials is less than 50 ppb, meeting the levels required in the semiconductor field.

[0061] According to the present invention as described above, organic impurities and inorganic impurities contained in the crude IPA product can be removed simultaneously by applying the dividing wall distillation column, and the phase and discharge stage of the final IPA discharged from the dividing wall distillation column can be controlled according to the content level of the inorganic materials contained in the crude IPA product, so that the IPA purification efficiency can be improved while achieving energy saving.

[0062] That is, when the content of inorganic materials contained in the crude IPA product is 50 ppb or less, the final IPA is discharged in the liquid phase, so that the residual levels of organic materials and inorganic materials required in the semiconductor field can be satisfied while minimizing energy consumption.

[0063] At the same time, when the content of inorganic materials contained in the crude IPA product is greater than 50 ppb, the final IPA is discharged in the gas phase, thereby separating inorganic materials in the form of ions or precipitates, and thus the limitations of removing inorganic materials by existing filtration devices or adsorption devices can be overcome. [Detailed Description of the Invention]

[0065] Hereinafter, the present invention will be described in more detail with reference to the embodiments. However, the following embodiments are provided to illustrate the present invention. It will be apparent to those skilled in the art that various modifications and changes can be made without departing from the scope and concept of the present invention, and the scope of the present invention is not limited thereto.

[0066] In the following examples and comparative examples, a commercial process simulation program Aspen Plus was used to simulate the method according to the present invention. As constants required for the simulation, values stored in the program, values described in the literature, etc. were used.

[0067] Examples:

[0068] Using Figure 2 the dividing wall distillation column to purify high-purity IPA from the crude IPA product.

[0069] First, a crude IPA product containing impurities was prepared with the composition shown in Table 1. The crude IPA product was fed to the first zone 10 of a dividing wall column (DWC), and a separation process was carried out under the conditions shown in Table 1, and the respective streams were discharged from the top zone 30, the bottom zone 40, and the second zone 20. The content of the residual impurities contained in the liquid-phase or gas-phase IPA discharged from the second zone 20 and the total energy consumed in the dividing wall column were measured and shown in Table 1.

[0070] [Table 1]

[0071]

[0072] It can be confirmed from Table 1 that based on the content (50 ppb) of the inorganic material contained in the crude IPA product, the phase and stage of the final IPA discharged from the dividing wall column affect the content of the residual impurities and the energy used. Specifically, in Example 1, a crude IPA product with an inorganic material content of less than 50 ppb was fed to the stage located at 50% of the first zone of the dividing wall column, and purified IPA was discharged in the liquid phase at a position corresponding to 40% of the second zone. As a result, the energy consumption was low, and the impurity residue level required in the semiconductor field was satisfied.

[0073] In Example 3, a crude IPA product with an inorganic material content of less than 50 ppb was fed to the stage located at 50% of the first zone, and purified IPA was discharged in the liquid phase at a position corresponding to 80% of the second zone. As a result, the residual amount of low-boiling organic materials decreased, but the residual amount of high-boiling organic materials increased, and finally the impurity residue level could not be satisfied.

[0074] In Example 2, a crude IPA product with an inorganic material content greater than 50 ppb was fed to the stage located at 50% of the first zone, and purified IPA was discharged in the gas phase at a position corresponding to 60% of the second zone. As a result, the energy consumption increased slightly, but the removal rate of the inorganic material contained in the feed was excellent, and the impurity residue level was satisfied.

[0075] In Example 4, a crude IPA product with an inorganic material content greater than 50 ppb was fed to the stage located at 50% of the first zone, and purified IPA was discharged in the gas phase at a position corresponding to 20% of the second zone. As a result, the energy consumption increased, and the residual amount of low-boiling organic materials was high, and finally the impurity residue level could not be satisfied.

[0076] Meanwhile, in Example 5, in the case of a crude IPA product with an inorganic material content greater than 50 ppb, purified IPA is discharged in the liquid phase at a position corresponding to 40% of the second region. As a result, although it is advantageous in terms of energy consumption compared to Example 2 where gas-phase discharge is carried out, the removal rate of inorganic materials is poor and the residual level of impurities cannot be satisfied.

[0077] [Description of Reference Numerals]

[0078] 100: Reaction unit

[0079] 200: Purification unit

[0080] 300: IPA purification unit

[0081] DW: Dividing wall

[0082] 10: First region

[0083] 20: Second region

[0084] 30: Top region

[0085] 40: Bottom region

Claims

1. A method for preparing isopropyl alcohol, the method comprising: S1, preparing a crude isopropyl alcohol (IPA) product by subjecting a reaction product of propylene and water to gas purification and isopropyl alcohol purification; S2, feeding the crude IPA product into a first region of a dividing wall distillation column, wherein the dividing wall distillation column comprises the first region, a second region, a top region, and a bottom region; and S3, in the dividing wall distillation tower, water and low-boiling-point organic materials contained in the crude IPA product are separated into the top region, high-boiling-point organic materials and inorganic materials contained in the crude IPA product are separated into the bottom region, and purified isopropyl alcohol in a liquid phase or a gas phase is obtained in the second region.

2. The method according to claim 1, wherein: The crude IPA product contains 0.08 wt % or less of the low-boiling point organic material, 0.05 wt % or less of the high-boiling point organic material, and 100 ppb or less of the inorganic material as impurities, based on the total weight of the crude IPA product.

3. The method according to claim 1, wherein: When the crude IPA product contains 50 ppb or less of the inorganic material based on the total weight of the crude IPA product, purified isopropyl alcohol in a liquid phase is obtained in the second zone of the dividing wall distillation column.

4. The method according to claim 1, wherein: When the crude IPA product contains more than 50 ppb to 100 ppb of the inorganic material based on the total weight of the crude IPA product, purified isopropyl alcohol in a vapor phase is obtained in the second zone of the dividing wall distillation column.

5. The method according to claim 1, wherein: In the second region of the dividing wall fractionation column, the level of purified isopropyl alcohol discharged in a gas phase is lower than the level of purified isopropyl alcohol discharged in a liquid phase.

6. The method according to claim 1, wherein: The crude IPA product is fed to a stage located 30% to 70% from an upper end of the first region of the dividing wall fractionation column.

7. The method according to claim 1, wherein: Purified isopropyl alcohol in a liquid phase is discharged from a stage located 20% to 70% from the upper end of the second region of the dividing wall fractionation column.

8. The method according to claim 1, wherein: Purified isopropyl alcohol in a gas phase is discharged from a stage located 40% to 80% from the upper end of the second region of the dividing wall fractionation column.

9. The method according to claim 1, wherein: The low-boiling point organic material separated to the top region of the dividing wall distillation column includes isopropyl ether, acetone, or a mixture thereof.

10. The method according to claim 1, wherein: The high boiling point organic material separated into the bottom area of ​​the dividing wall distillation column comprises n-propanol, hexanol or a mixture thereof, The inorganic material separated to the bottom region of the dividing wall fractionation column includes one or more metal components selected from the group consisting of Al, As, Fe, and Mg.

11. The method according to claim 1, wherein: In the liquid or gaseous purified isopropyl alcohol obtained in the second zone of the dividing wall distillation tower, the residual amount of the low-boiling point organic material is less than 50 ppm, the residual amount of the high-boiling point organic material is less than 20 ppm, and the residual amount of the inorganic material is less than 50 ppb, based on the weight of the purified isopropyl alcohol.

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