Method of preparing isopropyl alcohol

Abstract

The present invention provides a method of preparing isopropyl alcohol (IPA), and the method may comprise the steps of: (S1) supplying a reaction product of a propylene monomer and water to a gas purification part so as to isolate a gas component containing an unreacted propylene monomer; (S2) supplying, to a first organic material removal column, the reaction product from which the gas component is isolated, so as to discharge an upper stream comprising organic by-products and IPA and a lower stream comprising IPA, n-propyl alcohol (NPA) by-products and water; (S3) supplying the upper discharge stream of the first organic material removal column to a second organic material removal column and injecting process circulation water so as to discharge an upper stream comprising organic by-products and a lower stream comprising IPA and the process circulation water; and (S4) supplying the lower discharge stream of the first organic material removal column to an IPA purification part comprising a plurality of distillation columns, so as to isolate IPA.

Description

Method for producing isopropyl alcohol

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0119554, filed September 8, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a method for producing isopropyl alcohol, and more particularly, to a method for reducing energy consumption and minimizing loss of isopropyl alcohol.

[0005] Isopropyl alcohol (IPA) is used in a variety of applications, including as a solvent for cleaning agents, industrial paints and reagents, paints, and inks in the electronics industry, including semiconductor and liquid crystal display (LCD) manufacturing.

[0006] Such isopropyl alcohol can be produced by reacting propylene with water. For example, a gaseous reaction is performed between propylene monomer and water in a reaction section to obtain a reaction product comprising isopropyl alcohol, unreacted propylene monomer, unreacted water, and byproducts such as organic substances. The gaseous reaction product is then passed through a subsequent process tower to separate the propylene monomer, water, and byproducts, thereby purifying the isopropyl alcohol.

[0007] According to the IPA manufacturing process as shown in Fig. 1, a feed (1) containing propylene monomer and water is supplied to a reactor (100) and reacted to obtain a gaseous reaction product (101), and then the reaction product (101) is removed from a gas purification unit including an absorption tower (201) and a gas purification tower (202) to remove unreacted propylene gas (201a) and a low-boiling-point gas component (202a), and a stream (202b) containing IPA, water, and by-products from which the gas components have been removed is supplied to an organic matter removal tower (301) to remove organic by-products, and an upper stream (302a) containing IPA, a lower stream (302b) containing water, and a side stream (302c) containing NPA are separated in the water removal tower (302), and the upper stream (302a) is supplied to an IPA recovery tower (303) to obtain IPA from which water has been separated by a solvent. The stream (303a) containing the solvent and water separated in the IPA recovery tower (303) is separated into an upper stream of solvent (304a) and a lower stream of water (304b) in the solvent recovery tower (304).

[0008] In the above IPA purification process, a portion of the water (302b) recovered from the bottom of the water removal tower (302) can be recovered and used as process circulating water. Typically, circulating water of eight times or more the amount of IPA produced is used, and about 40% of the circulating water used is fed to the absorption tower (201) to separate the gaseous IPA into a liquid phase by absorbing it into water, and the remaining about 60% is fed to the organic matter removal tower (301) to remove organic byproducts such as diisopropyl ether (DIPE) and hexene using liquid-liquid phase equilibrium.

[0009] At this time, as the liquid stream (202b) containing IPA, water, and by-products from which gas components have been removed in the gas purification unit of the front stage and a large amount of circulating water are fed together into the organic matter removal tower (301), the flow rate supplied to the water removal tower (302) located at the rear end of the organic matter removal tower (301) may excessively increase, which causes the steam demand to increase.

[0010] Therefore, a method is required to reduce the steam requirement throughout the IPA manufacturing process and thereby achieve energy savings.

[0011] The present invention is intended to solve the problems mentioned in the background technology of the above invention, and provides a method for minimizing energy consumption and cost increase by reducing the use of circulating water in the process of manufacturing isopropyl alcohol.

[0012] According to one aspect of the present invention for solving the above problem,

[0013] (S1) A step of supplying a reaction product of propylene monomer and water to a gas purification unit to separate a gas component including unreacted propylene monomer;

[0014] (S2) A step of supplying the reaction product from which the above gas components are separated to a first organic material removal tower to discharge an upper stream containing organic by-products and isopropyl alcohol and a lower stream containing isopropyl alcohol (IPA), n-propyl alcohol (NPA) by-products and water;

[0015] (S3) A step of supplying the upper discharge stream of the first organic matter removal tower to the second organic matter removal tower and introducing process circulation water to discharge an upper stream containing organic byproducts and a lower stream containing isopropyl alcohol and process circulation water; and

[0016] (S4) A method for producing isopropyl alcohol is provided, including the step of supplying the bottom discharge stream of the first organic matter removal tower to an isopropyl alcohol (IPA) purification unit including a plurality of distillation towers to separate isopropyl alcohol.

[0017] According to the present invention, by applying two organic matter removal towers, an upper stream containing organic byproducts and a portion of isopropyl alcohol is separated in the first organic matter removal tower without supplying process circulation water, and the separated upper stream is brought into contact with a small amount of process circulation water in the second organic matter removal tower to dissolve IPA, thereby separating organic byproducts and isopropyl alcohol, thereby lowering the supply flow rate of the subsequent IPA purification unit and reducing the amount of steam used.

[0018] Reducing the amount of steam used in this IPA purification unit can realize energy savings for the entire process and minimize cost increases by reducing the size of the distillation column used for IPA purification.

[0019] Figure 1 shows the process sequence of conventional IPA manufacturing.

[0020] Figure 2 illustrates an IPA manufacturing method according to one embodiment of the present invention.

[0021] The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0022] As used herein, the terms “include” or “contain” specify a particular characteristic, area, integer, step, operation, element, or component, but do not exclude the addition of other particular characteristics, areas, integers, steps, operations, elements, or components.

[0023] The term "stream" as used herein may refer to the flow of fluid within a process, or may refer to the fluid itself flowing within a pipe. Specifically, the stream may refer to both the fluid itself flowing within the pipe connecting each device and the flow of the fluid. Furthermore, the fluid may include one or more components of gas, liquid, and solid.

[0024] The term "upper" as used herein, unless otherwise specified, means a point 0 to 20% in height downward from the top of the device, and may specifically mean the top (top). In addition, the term "lower" means a point 80 to 100% in height downward from the top of the device, and may specifically mean the bottom (bottom).

[0025] The term 'side stream' as used herein may mean a stream discharged from the top of the device at a height of 25 to 80% or from 40 to 70% downwards, unless otherwise specified.

[0026] Additionally, the “pressure” referred to herein means gauge pressure measured relative to atmospheric pressure.

[0027] Meanwhile, in the present invention, in devices such as absorption towers, purification towers, removal towers, and recovery towers, the operating temperature of the device may refer to the temperature at the top or bottom of the device unless otherwise specified. In addition, the operating pressure of the device may refer to the pressure at the top of the device unless otherwise specified.

[0028]

[0029] One embodiment of the present invention relates to a method for producing isopropyl alcohol (IPA). Hereinafter, the method for producing IPA of the present invention will be described in detail with reference to the drawings.

[0030] FIG. 2 illustrates a method for producing isopropyl alcohol according to one embodiment of the present invention, and isopropyl alcohol can be produced using a system including a reactor (100); a gas purification unit including an absorption tower (201) and a gas purification tower (202); an IPA purification unit including a first organic matter removal tower (301'), a second organic matter removal tower (302"); a water removal tower (302), an IPA recovery tower (303), a solvent recovery tower (304), and a high boiling point material removal tower (305). In addition, the system can be used by additionally installing a reboiler for heating the feed stream of each tower by transferring heat to it, a condenser for converting an upper stream generated by the heating from a gas phase to a liquid phase, a decanter for separating the condensed stream from a liquid phase, a valve for controlling the flow of the stream, a pump, etc.

[0031] Referring to FIG. 2, a feed (1) containing propylene monomer and water is supplied to a reactor (100), and a reaction product (101) containing isopropyl alcohol can be obtained through a gas phase reaction process.

[0032] Since only a portion of the propylene monomer supplied to the reactor (100) is used for the reaction, the reaction product may include unreacted propylene monomer and unreacted water in addition to isopropyl alcohol produced by the reaction of the propylene monomer and water. For example, the reaction product (101) may include 65 to 85 wt% of unreacted propylene monomer, 4 to 8 wt% of isopropyl alcohol, and 5 to 30 wt% of water. In addition, the reaction product may include organic substances such as isopropyl ether (DIPE), hexene, hexanol, and acetone, n-propyl alcohol (NPA), etc. as byproducts. Therefore, a process for separating unreacted raw materials from the reaction product and purifying isopropyl alcohol from various byproducts is required.

[0033] First, the reaction product (101) obtained by the gas phase reaction of propylene monomer and water is supplied to a gas purification unit to separate the gas component containing unreacted propylene monomer (S1).

[0034] Specifically, the reaction product (101) is supplied to the bottom of the absorption tower (201), and process circulation water is injected into the top of the absorption tower (201) to separate unreacted propylene monomer. At this time, the process circulation water may be water recovered from a distillation tower, i.e., a water removal tower (302), included in an IPA purification unit at the rear. In the absorption tower (201), the gaseous isopropyl alcohol included in the reaction product is absorbed into the process circulation water and obtained as a lower liquid stream (201b), and a gaseous stream (201a) including unreacted propylene monomer can be separated from the top. The unreacted propylene monomer included in the gaseous stream (201a) is recovered to the reactor (100) and reused as a raw material for producing isopropyl alcohol.

[0035] In one embodiment of the present invention, the flow rate of the process circulation water supplied to the absorption tower (201) may be 15 to 40 wt% or 15 to 35 wt% of the flow rate of the reaction product. When the process wash water is supplied at a flow rate within the above range, the absorption capacity of the isopropyl alcohol contained in the reaction product can be improved, while at the same time, the energy cost for recovering the process circulation water at the subsequent stage can be prevented from increasing excessively.

[0036] The above absorption tower (201) has a temperature of 90 to 100 ℃ or 90 to 95 ℃ and a pressure of 25 to 40 kg / cm 2 ·g or 25 to 35 kg / cm 2 · It can be operated at a pressure of g. When the above operating conditions are satisfied, the upper discharge stream containing unreacted propylene monomer and the lower discharge stream containing isopropyl alcohol can be effectively separated.

[0037] Meanwhile, the lower liquid stream of the absorption tower (201) may contain a small amount of low-boiling-point gas components, including unreacted propylene monomers that have not yet been separated, in addition to isopropyl alcohol and unreacted water. For example, the content of low-boiling-point gas components, including unreacted propylene monomers, contained in the lower liquid stream of the absorption tower (201) may be 5 wt% or less or in the range of 2 to 5 wt%.

[0038] Accordingly, the liquid stream (201b) containing isopropyl alcohol separated from the absorption tower (201) can be supplied to one or more gas purification towers (202) to be separated into an upper stream (202a) containing low-boiling-point components and a lower stream (202b) containing isopropyl alcohol, water, and by-products.

[0039] If necessary, the lower liquid stream of the absorption tower (201) may be supplied to the gas purification tower (202) after passing through one or more flash drums. That is, the low-boiling-point components are first separated in the flash drum, and then supplied to the gas purification tower (202) to separate the low-boiling-point components of unreacted propylene monomer and inert gas from the upper portion and a small amount of high-boiling-point components from the lower portion.

[0040] The upper stream (202a) containing low-boiling-point components separated from the gas purification tower (202) may include unreacted propylene monomer and inert gases (e.g., ethane, propane). The unreacted propylene monomer contained in the upper stream of the gas purification tower (202) may be recovered to the reactor (100), and the inert gases may be branched off for exhaust.

[0041] Meanwhile, the bottom stream (202b) separated from the gas purification tower (202) may include isopropyl alcohol, water, and organic substances such as n-propyl alcohol (NPA), isopropyl ether (DIPE), hexene, and acetone as byproducts.

[0042] Therefore, it is necessary to remove organic byproducts from the bottom discharge stream (202b) of the gas purification tower.

[0043] In the conventional IPA manufacturing process, in order to remove organic by-products from the reaction product from which the gas component has been separated, the process circulation water recovered from the water removal tower (302) is supplied to the organic removal tower and used to separate the organic by-products using the liquid-liquid phase equilibrium. The process circulation water is supplied at 70 to 95 wt% or 80 to 90 wt% of the feed stream flow rate of the organic removal tower and used to dissolve isopropyl alcohol. In this case, there is a problem that the steam demand increases due to excessive flow rate because the process circulation water used in the absorption tower in the front stage and the process circulation water used in the organic removal tower are combined and fed into the distillation tower of the IPA purification unit in the back stage.

[0044] To solve this problem, the present invention applies two organic removal towers, in which the first organic removal tower separates an upper stream containing organic by-products and a portion of isopropyl alcohol without supplying process circulation water, and the separated upper stream is brought into contact with a small amount of process circulation water in the second organic removal tower to dissolve IPA, thereby removing organic by-products.

[0045] To explain more specifically, first, the reaction product from which the gas component is separated, i.e., the gas purification tower bottom discharge stream (202b), is supplied to the first organic matter removal tower (301'), and component separation according to boiling point is performed without supplying process circulation water (S2).

[0046] The stream supplied to the first organic matter removal tower (301') may include isopropyl alcohol, water, n-propyl alcohol (NPA) byproduct, and organic byproduct (e.g., diisopropyl ether (DIPE), hexene, hexanol, acetone, or a mixture thereof).

[0047] Since process circulation water is not supplied during component separation in the first organic removal tower (301'), isopropyl alcohol is not dissolved by water. Therefore, the stream heated by the heat provided from the reboiler connected to the lower portion of the first organic removal tower (301') and moved upward and then discharged through the condenser may include a portion of isopropyl alcohol together with organic byproducts. For example, the upper stream (301'a) of the first organic removal tower may include 5 to 25 wt%, specifically 10 to 20 wt%, of the total isopropyl alcohol supplied to the first organic removal tower.

[0048] As a result, the stream supplied to the first organic matter removal tower (301') can be separated into an upper stream (301'a) containing organic byproducts and isopropyl alcohol and a lower stream (301'b) containing isopropyl alcohol, n-propyl alcohol (NPA) byproducts, and water.

[0049] In order to recover isopropyl alcohol contained in the upper stream (301'a) of the first organic matter removal tower, the upper discharge stream (301'b) of the first organic matter removal tower is supplied to the second organic matter removal tower (301") and a small amount of process circulation water is injected to separate the upper stream (301"a) containing organic by-products and the lower stream (301"b) containing isopropyl alcohol and process circulation water (S3).

[0050] More specifically, a second organic matter removal tower (301") is arranged at the rear end of a condenser connected to the first organic matter removal tower (301'), and a stream (301'a) containing organic by-products and isopropyl alcohol is supplied to the second organic matter removal tower (301"). In this case, the content of isopropyl alcohol contained in the stream (301'a) supplied to the second organic matter removal tower (301") is at a level corresponding to 10% to 20% of the isopropyl content contained in the feed stream of the first organic matter removal tower (301'). Therefore, even if a small amount of process circulation water is injected into the second organic matter removal tower (301"), the isopropyl alcohol contained in the feed stream (301'a) can be effectively separated. That is, a small amount of process circulation water can selectively dissolve the isopropyl alcohol contained in the feed stream by utilizing the difference in solubility and move to the lower portion, thereby separating it from the organic by-products.

[0051] The isopropyl alcohol dissolved in the above process circulation water is discharged to the bottom stream (301"b) of the second organic matter removal tower and then recycled to the first organic matter removal tower (301'), thereby minimizing the loss of isopropyl alcohol.

[0052] In one embodiment of the present invention, the first organic matter removal tower (301') has a temperature of 75 to 130°C or 80 to 105°C and a pressure of 0 to 2 kg / cm 2 ·g or 0 to 0.5 kg / cm 2 · It can be operated at a pressure of g. When the above operating conditions are satisfied, organic by-products can be effectively separated from the mixed stream without supplying process circulation water.

[0053] In addition, the second organic matter removal tower (301") has a temperature of 75 to 125 ℃ or 80 to 105 ℃ and a pressure of 0 to 2 kg / cm 2 ·g or 0 to 0.5 kg / cm 2· It can be operated at a pressure of g. When the above operating conditions are satisfied, the efficiency of dissolving isopropyl alcohol can be increased even by injecting a small amount of process circulation water.

[0054] In the second organic matter removal tower (301"), the flow rate of the process circulation water can be adjusted so that the process circulation water and isopropyl alcohol come into contact at a weight ratio of 2.5:1 to 5:1. This flow rate of the process circulation water is a significantly reduced amount compared to the process circulation water supplied in an amount of about 80 wt% or more relative to the feed stream from the existing organic matter removal tower in the conventional IPA manufacturing process. This can reduce the amount of steam used by lowering the supply flow rate of the distillation tower included in the subsequent IPA purification unit.

[0055] Meanwhile, the liquid stream (301'b) separated from the lower portion of the first organic matter removal tower (301') may contain 9 to 12 wt% of isopropyl alcohol, 0.1 to 1 wt% of n-propyl alcohol, and 87 to 90 wt% of water based on the total weight thereof.

[0056] That is, since the liquid stream (301'b) may contain a large amount of water, including unreacted water discharged from the reactor (100), process circulation water used to absorb gaseous isopropyl alcohol in the absorption tower (201), and n-propyl alcohol (NPA), which is a reaction by-product, a large amount of water and NPA by-products are removed in an IPA purification unit including a plurality of distillation towers to separate high-purity isopropyl (S4).

[0057] Specifically, the bottom discharge stream (301'b) of the first organic matter removal tower (301') is supplied to the water removal tower (302) to separate and discharge an upper stream (302a) containing isopropyl alcohol, a bottom stream (302b) containing water, and a side stream containing n-propyl alcohol (NPA).

[0058] The upper stream (302a) separated from the water removal tower (302) contains an azeotropic mixture of isopropyl alcohol and water, and may contain, for example, 85 to 90 wt% of isopropyl alcohol and 10 to 15 wt% of water.

[0059] The water separated into the bottom stream (302b) of the water removal tower (302) can be recovered and used as process circulating water. As previously described, the water separated from the water removal tower (302) can be supplied to the absorption tower (201) in the upstream stage and used to absorb gaseous isopropyl alcohol. In addition, since the water separated from the water removal tower (302) has a high temperature exceeding 100°C, it can also be used for heat exchange to preheat the water supplied to the reactor (100) as needed.

[0060] The above water removal tower (302) has a temperature of 70 to 150 ℃ or 80 to 140 ℃ and a pressure of 0 to 5 kg / cm 2 ·g or 0 to 3 kg / cm 2 · It can be operated at a pressure of g. When the above operating conditions are satisfied, the azeotropic mixture of isopropyl alcohol and water can be effectively separated.

[0061] Thereafter, the upper discharge stream (302a) of the water removal tower (302) is supplied to the IPA recovery tower (303), and an organic solvent (e.g., cyclohexane, benzene, etc.) as an azeotrope is introduced to discharge an upper stream (303a) containing water and an organic solvent and a lower stream containing IPA. That is, in the IPA recovery tower (303), the azeotrope of isopropyl alcohol and water is broken by the organic solvent, thereby obtaining isopropyl alcohol purified to a high purity.

[0062] The water and organic solvent stream (303a) separated from the upper portion of the IPA recovery tower can be supplied to the solvent recovery tower (304) and separated into an upper stream of solvent (304a) and a lower stream of water (304b) and discharged. The solvent stream (304) can be recycled to the IPA recovery tower (303).

[0063] Meanwhile, the side discharge stream (302c) of the water removal tower (302) containing n-propyl alcohol (NPA) is supplied to the high boiling point material removal tower (305) to discharge a stream (305b) containing NPA to the bottom, and the upper stream (305a) can be recycled back to the water removal tower (302).

[0064] According to the present invention as described above, by applying two organic matter removal towers, an upper stream containing organic by-products and a portion of isopropyl alcohol is separated in the first organic matter removal tower without supplying process circulation water, and the separated upper stream is brought into contact with a small amount of process circulation water in the second organic matter removal tower to dissolve IPA, thereby separating organic by-products and isopropyl alcohol, thereby lowering the supply flow rate of the subsequent IPA purification unit and reducing the amount of steam used.

[0065] Reducing the amount of steam used in this IPA purification unit can realize energy savings for the entire process and minimize cost increases by reducing the size of the distillation column used for IPA purification.

[0066] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are intended to illustrate the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical spirit of the present invention, and the scope of the present invention is not limited to these examples alone.

[0067] The following examples and comparative examples simulate the method according to the present invention using the commercial process simulation program Aspen Plus. The constants required for the simulations were values ​​built into the program and values ​​described in the literature.

[0068] Example 1

[0069] As shown in Fig. 2, isopropyl alcohol was produced using a system including a reactor (100); a gas purification unit including an absorption tower (201) and a gas purification tower (202); a first organic matter removal tower (301'), a second organic matter removal tower (302"); an IPA purification unit including a water removal tower (302), an IPA recovery tower (303), a solvent recovery tower (304), and a high-boiling-point substance removal tower (305).

[0070]

[0071] (Step 1) Gas separation in the gas purification unit

[0072] After supplying a feed (1) containing 100°C water and propylene monomer to the above reactor (100) and causing a gas phase reaction, the obtained reaction product (101) was supplied to the bottom of the absorption tower (201), and 40% of the process circulation water recovered from the water removal tower (302) of the IPA purification unit was injected into the top of the absorption tower (201).

[0073] In the above absorption tower (201), a liquid stream (201b) in which gaseous isopropyl alcohol was absorbed was discharged to the bottom, and a gaseous stream (201a) containing unreacted propylene monomer was separated to the top and circulated to the reactor (100).

[0074] The liquid stream (201b) in which the above isopropyl alcohol was absorbed was passed through a gas purification tower (202) and separated into a low-boiling-point upper stream (202a) and a lower stream (202b) containing isopropyl alcohol, water, and by-products.

[0075]

[0076] (Step 2) Separation of organic by-products without supplying process circulation water in the first organic matter removal tower

[0077] The bottom stream (202b) of the above gas purification tower was supplied to the first organic matter removal tower (301'), and component separation was performed according to boiling point without supplying process circulation water, thereby separating the top stream (301'a) containing organic by-products and a portion of isopropyl alcohol (about 10% of the total isopropyl alcohol) and the bottom stream (301'b) containing isopropyl alcohol, n-propyl alcohol (NPA) by-products, and water.

[0078]

[0079] (Step 3) Recover some IPA by injecting process circulation water into the second organic matter removal tower.

[0080] The upper discharge stream (301'b) of the first organic matter removal tower (301') was supplied to the second organic matter removal tower (301"), and a portion of the process circulation water recovered from the water removal tower (302) of the IPA purification unit was supplied thereto, thereby separating the upper stream (301"a) containing organic by-products and the lower stream (301"b) containing isopropyl alcohol and process circulation water. The lower stream (301"b) was recovered and recycled to the first organic matter removal tower (301'). At this time, the supply flow rate of the process circulation water was controlled so that the process circulation water and the isopropyl alcohol came into contact at a flow rate ratio of 3:1 in the second organic matter removal tower (301"), and as a result, the flow rate of the stream (202b) supplied to the first organic matter removal tower (301') was 6 wt%.

[0081]

[0082] (Step 4) IPA separation in the IPA purification unit

[0083] The stream (301'b) discharged from the lower portion of the first organic matter removal tower (301') was supplied to the water removal tower (302), and an upper stream (302a) containing isopropyl alcohol, a lower stream (302b) containing water, and a side stream containing n-propyl alcohol (NPA) were separated and discharged. After recovering water as the lower stream (302b), a portion thereof was supplied to the pre-absorption tower (201) and the second organic matter removal tower (301").

[0084] The upper discharge stream (302a) of the water removal tower (302) was supplied to the IPA recovery tower (303), and cyclohexane was introduced as an azeotropic agent to discharge the upper stream (303a) containing water and cyclohexane, and IPA was separated from the lower stream.

[0085] Meanwhile, the side discharge stream (302c) of the water removal tower (302) containing n-propyl alcohol (NPA) was supplied to the high boiling point material removal tower (305), and the stream (305b) containing NPA was discharged to the bottom, and the upper stream (305a) was recycled back to the water removal tower (302).

[0086]

[0087] Comparative Example 1

[0088] As shown in Fig. 1, isopropyl alcohol was produced using a system including a reactor (100); a gas purification unit including an absorption tower (201) and a gas purification tower (202); an organic matter removal tower (301); and an IPA purification unit including a water removal tower (302), an IPA recovery tower (303), a solvent recovery tower (304), and a high-boiling-point material removal tower (305).

[0089]

[0090] (Step 1) Gas separation in the gas purification unit

[0091] The same process as step 1 of Example 1 was performed.

[0092]

[0093] (Step 2) Separation of organic by-products by supplying process circulation water from one organic removal tower

[0094] The bottom stream (202b) of the gas purification tower was supplied to the organic matter removal tower (301), and the process circulation water recovered from the water removal tower (302) of the IPA purification unit was supplied so as to be 88 wt% of the flow rate of the stream (202b) supplied to the organic matter removal tower (301), thereby separating it into a liquid phase (301a) containing organic by-products and a liquid phase (301b) containing isopropyl alcohol and water. The process circulation water was used as water separated and recovered in the water removal tower (302) at the rear end.

[0095]

[0096] (Step 3) IPA separation in the IPA purification unit

[0097] The stream (301b) discharged from the lower portion of the organic matter removal tower (301) was supplied to the water removal tower (302), and an upper stream (302a) containing isopropyl alcohol, a lower stream (302b) containing water, and a side stream containing n-propyl alcohol (NPA) were separated and discharged. After recovering water as the lower stream (302b), it was supplied to the pre-absorption tower (201) and the organic matter removal tower (301).

[0098] The upper discharge stream (302a) of the water removal tower (302) was supplied to the IPA recovery tower (303), and cyclohexane was introduced as an azeotropic agent to discharge the upper stream (303a) containing water and cyclohexane, and IPA was separated from the lower stream.

[0099] Meanwhile, the side discharge stream (302c) of the water removal tower (302) containing n-propyl alcohol (NPA) was supplied to the high boiling point material removal tower (305), and the stream (305b) containing NPA was discharged to the bottom, and the upper stream (305a) was recycled back to the water removal tower (302).

[0100]

[0101] Comparative Example 2

[0102] The same process as in Comparative Example 1 was performed, except that the process circulation water recovered from the water removal tower (302) of the IPA purification unit was supplied to the organic matter removal tower (301) so that it was 6 wt% of the flow rate of the feed stream (202b).

[0103]

[0104] Table 1 below shows a comparison of the IPA purification process and its results according to examples and comparative examples.

[0105] IPA Purification Process Example 1 Comparative Example 1 Comparative Example 2 Organic Removal Tower Feed Stream Flow Rate 1) 111 Circulating water flow rate (Tower 1) - 0.88 0.06 Circulating water flow rate (Tower 2) 0.06 -- Organic matter removal rate 100% 100% 100% Feed stream flow rate of water removal tower 1.18 1.98 1.16 IPA recovery rate 99.98% 99.98% 76% Steam usage 2) 0.77111) The flow rate of the stream supplied to the organic matter removal tower is set to "100", and the flow rate of the supply stream of the circulating water and water removal towers is expressed as a ratio based on this. 2) Steam usage represents the total steam usage used in the organic matter removal tower (including the first and second towers) and the water removal tower.

[0106] As can be seen in Table 1 above, Example 1 separated an upper stream containing organic byproducts and a portion of IPA in the first organic removal tower without supplying process circulation water, and then injected a small amount of process circulation water (6% of the feed stream flow rate of the first organic removal tower) into the second organic removal tower to dissolve the IPA contained in the upper stream of the first organic removal tower and separate the organic byproducts and isopropyl alcohol, thereby lowering the feed flow rate of the water removal tower in the IPA purification unit, thereby reducing the amount of steam used, and maintaining a high IPA recovery rate.

[0107] In contrast, in Comparative Example 1, as process circulation water corresponding to 88% of the feed stream flow rate was injected into one organic matter removal tower, the feed stream flow rate of the water removal tower excessively increased, resulting in an increase in steam usage.

[0108] Meanwhile, Comparative Example 2 is a case where the flow rate of circulating water is applied differently under the same conditions as Comparative Example 1 in terms of steam usage. As a single organic matter removal tower is applied and a small amount of process circulating water is injected, the supply flow rate of the water removal tower is lowered. However, it can be confirmed that the IPA recovery rate is greatly reduced because the amount of circulating water in the organic matter removal tower is insufficient compared to the IPA in the feed stream, and thus the IPA cannot be sufficiently dissolved.

[0109]

[0110] [Explanation of symbols]

[0111] 100: Reactor

[0112] 201: Absorption tower

[0113] 202: Gas purification tower

[0114] 301, 301', 301": Organic matter removal tower

[0115] 302: Water removal tower

[0116] 303: IPA recovery tower

[0117] 304: Solvent recovery tower

[0118] 305: High-boiling-point substance removal tower

Claims

1. (S1) A step of supplying a reaction product of propylene monomer and water to a gas purification unit to separate a gas component including unreacted propylene monomer; (S2) A step of supplying the reaction product from which the above gas components are separated to a first organic material removal tower to discharge an upper stream containing organic by-products and isopropyl alcohol and a lower stream containing isopropyl alcohol (IPA), n-propyl alcohol (NPA) by-products and water; (S3) A step of supplying the upper discharge stream of the first organic matter removal tower to the second organic matter removal tower and introducing process circulation water to discharge an upper stream containing organic byproducts and a lower stream containing isopropyl alcohol and process circulation water; and (S4) A method for producing isopropyl alcohol, comprising the step of supplying the bottom discharge stream of the first organic matter removal tower to an isopropyl alcohol (IPA) purification unit including a plurality of distillation towers to separate isopropyl alcohol.

2. In paragraph 1, The above step (S1) is a method for producing isopropyl alcohol, which includes contacting a reaction product of propylene monomer and water with process circulation water in an absorption tower of a gas purification unit to remove a gaseous stream containing unreacted propylene monomer, and then separating a low-boiling-point gas component from a liquid stream containing components absorbed in the process circulation water.

3. In paragraph 1, A method for producing isopropyl alcohol, wherein the stream supplied to the first organic matter removal tower in the above step (S2) comprises isopropyl alcohol, water, n-propyl alcohol (NPA) by-product, and organic by-product.

4. In paragraph 3, A method for producing isopropyl alcohol, wherein the organic by-product comprises diisopropyl ether (DIPE), hexene, hexanol, acetone or a mixture thereof.

5. In paragraph 1, A method for producing isopropyl alcohol in which process circulation water is not supplied to the first organic matter removal tower in the above step (S2).

6. In paragraph 1, A method for producing isopropyl alcohol, wherein the upper discharge stream of the first organic matter removal tower contains 5 to 15 wt% of the total isopropyl alcohol supplied to the first organic matter removal tower.

7. In paragraph 1, A method for producing isopropyl alcohol, wherein in the above step (S3), the second organic matter removal tower is placed at the rear end of a condenser connected to the first organic matter removal tower.

8. In paragraph 1, A method for producing isopropyl alcohol, wherein the process circulation water supplied to the second organic matter removal tower selectively dissolves isopropyl alcohol in a stream containing organic byproducts and isopropyl alcohol, thereby inducing liquid-liquid separation.

9. In paragraph 8, A method for producing isopropyl alcohol, wherein the isopropyl alcohol dissolved in the above process circulation water is discharged to the bottom of the second organic matter removal tower and then recycled to the first organic matter removal tower.

10. In paragraph 1, A method for producing isopropyl alcohol, wherein the process circulation water is supplied in the second organic matter removal tower at a flow rate such that the process circulation water and isopropyl alcohol come into contact at a weight ratio of 2.5:1 to 5:

1.

11. In paragraph 1, The above step (S4) supplies the bottom discharge stream of the first organic matter removal tower to the water removal tower of the IPA purification unit and discharges it as an upper stream containing a mixture of isopropyl alcohol and water, a bottom stream containing water, and a side stream containing n-propyl alcohol (NPA). The upper discharge stream of the water removal tower and the organic solvent are supplied to the IPA recovery tower of the IPA purification unit, and an upper stream containing water and an organic solvent and a lower stream containing IPA are discharged. The upper discharge stream of the IPA separation tower is supplied to the solvent recovery tower of the IPA purification unit to discharge the upper stream of solvent and the lower stream of water. A method comprising supplying a side discharge stream of the water removal tower to a high boiling point material removal tower of the IPA purification unit to discharge a stream containing NPA downward.

12. In paragraph 11, A method in which water contained in the bottom discharge stream of the water removal tower in the above IPA purification unit is recovered and used as process circulating water.

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