Method of preparing isopropyl alcohol

Abstract

The present invention provides a method for preparing isopropyl alcohol (IPA), the method comprising the steps of: (S1) reacting propylene and water in a reaction unit to obtain a reaction product including isopropyl alcohol (IPA); (S2) supplying the reaction product to a gas purification unit to separate a gas component including unreacted propylene; and (S3) supplying the reaction product from which the gas component is separated to an IPA purification unit to obtain purified isopropyl alcohol, wherein raw propylene can be additionally supplied to the gas purification unit to purify raw propylene and unreacted propylene.

Description

Method for producing isopropyl alcohol

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0119564, filed September 8, 2023, and Korean Patent Application No. 10-2024-0085390, filed June 28, 2024, 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 specifically, to a method for producing high-purity isopropyl alcohol by purifying propylene used as a raw material together with unreacted propylene.

[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 (C3H6) with water. Typically, isopropyl alcohol is produced by reacting propylene monomer with water in a reaction unit (100) as shown in FIG. 1 to obtain a reaction product including IPA, unreacted propylene monomer, unreacted water, n-propyl alcohol (NPA), and byproducts such as organic substances. The reaction product is then transferred to a gas purification unit (200) to separate low-boiling-point gas components including unreacted propylene monomer, and the reaction product from which the gas components have been separated is then supplied to an IPA purification unit (300) including a plurality of distillation columns to remove organic substances, NPA, and water, thereby obtaining a crude isopropyl alcohol product.

[0007] Propylene (C3H6) supplied as a raw material to the above reaction unit preferably has high purity. If propylene contains impurities such as unsaturated hydrocarbons such as ethylene, butene, and pentene, byproducts (e.g., ethanol) with a boiling point similar to that of IPA may be generated during the reaction between propylene and water. In addition, impurities with a boiling point similar to that of IPA, such as ethanol and n-propyl alcohol (NPA), may already exist in the raw propylene.

[0008] Therefore, purification of raw propylene is necessary to obtain high-purity IPA. As shown in Fig. 2, in the existing IPA manufacturing process, a raw material purification unit (10) including two columns is installed in front of the reaction unit to remove impurities contained in the raw propylene.

[0009] However, when operating an IPA manufacturing system with a raw material purification unit installed for quality control of raw material propylene, not only does energy consumption increase due to steam use, but also facility costs and operating costs increase due to the addition of columns.

[0010] The present invention is intended to solve the problems mentioned in the background technology of the above invention, and relates to a method for producing high-purity isopropyl alcohol by refining propylene used as a raw material together with unreacted propylene.

[0011] According to one aspect of the present invention for solving the above problem,

[0012] (S1) A step of reacting propylene and water in a reaction section to obtain a reaction product containing isopropyl alcohol (IPA);

[0013] (S2) a step of supplying the above reaction product to a gas purification unit to separate a gas component including unreacted propylene; and

[0014] (S3) A step of supplying the reaction product from which the above gas component is separated to an IPA purification unit to obtain purified isopropyl alcohol,

[0015] A method for producing isopropyl alcohol is provided, in which raw material propylene is additionally supplied to the above gas purification unit to purify raw material propylene and unreacted propylene.

[0016] In the present invention, raw material propylene can be supplied to a higher position than unreacted propylene in the gas purification tower.

[0017] According to the present invention, since purification of propylene and unreacted propylene used as raw materials in the gas purification step of the isopropyl manufacturing process is performed simultaneously, there is no need to add a separate column for purification of raw material propylene.

[0018] In addition, by supplying raw material propylene to a higher position than unreacted propylene in the gas purification tower, it is possible to efficiently simultaneously purify unreacted propylene and raw material propylene with a high content of impurities such as propane while minimizing energy consumption.

[0019] In this way, by integrating the purification of raw propylene and the purification of unreacted propylene, not only can the equipment costs and operating costs associated with adding a separate column be reduced compared to the existing isopropyl manufacturing process, but energy consumption can also be reduced.

[0020] Figure 1 schematically illustrates a typical isopropyl alcohol manufacturing process.

[0021] Figure 2 schematically illustrates a conventional isopropyl alcohol manufacturing process in which purification of raw propylene is performed separately.

[0022] FIG. 3 schematically illustrates an isopropyl alcohol manufacturing process that integrates purification of raw propylene and purification of unreacted propylene according to one embodiment of the present invention.

[0023] Figure 4 illustrates the process of Figure 3 in more detail.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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).

[0028] The term 'side stream' as used herein may mean a stream discharged from a height of 10 to 80% or from 10 to 70% downward from the top of the device, unless otherwise specified.

[0029] Additionally, the “pressure” referred to herein means gauge pressure measured relative to atmospheric pressure.

[0030] 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.

[0031]

[0032] 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.

[0033] FIG. 3 schematically illustrates an isopropyl alcohol manufacturing process that integrates purification of raw propylene and purification of unreacted propylene according to one embodiment of the present invention.

[0034] Referring to FIG. 3, the method for producing isopropyl alcohol according to the present invention includes a step (S1) of reacting propylene and water in a reaction unit (100), a step (S2) of purifying unreacted propylene in a gas purification unit (200), and a step (S3) of obtaining high-purity IPA in an IPA purification unit (300), and is characterized in that raw material propylene is supplied to the gas purification unit, purified together with unreacted propylene, and then supplied to the reaction step.

[0035] FIG. 4 illustrates in more detail an isopropyl alcohol manufacturing process according to one embodiment of the present invention, wherein isopropyl alcohol can be manufactured using a system including a reaction unit (100); a gas purification unit including an absorption tower (201), a flash drum / gas separation tower (202), and a gas purification tower (203); and an IPA purification unit including an organic matter removal tower (301), a water removal tower (302), an IPA recovery tower (303), a solvent recovery tower (304), and an NPA 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 the upper stream generated by the heating from a gas phase to a liquid phase, a decanter for separating the condensed stream into a liquid-liquid phase, a valve for controlling the flow of the stream, a pump, etc.

[0036] First, a reaction product (101) containing isopropyl alcohol can be obtained through a gas phase reaction of propylene monomer and water in the above reaction section (100).

[0037] It is preferable that the propylene (C3H6) supplied as a raw material to the above reaction unit (100) has high purity. If propylene contains impurities such as other unsaturated hydrocarbons such as ethylene, butene, pentene, ethane, propane, and carbon dioxide, a byproduct (e.g., ethanol) with a boiling point similar to IPA may be generated during the reaction between propylene and water.

[0038] Therefore, in order to obtain high-purity IPA, purification of raw material propylene is required, and in the present invention, raw material propylene is purified in a gas purification unit located at the rear end of the reaction unit (100), specifically, a gas purification tower (203), to remove impurities, and then supplied to the reaction unit (100).

[0039] In one embodiment of the present invention, the purified propylene supplied to the reaction unit (100) preferably contains propylene of 97 wt% or more, for example, 97 to 99.8 wt%, based on the total weight thereof, and has an impurity content of less than 3 wt%.

[0040] Meanwhile, only a portion of the purified propylene supplied to the reaction unit (100) is used in the reaction. Therefore, the reaction product may include unreacted propylene monomer and unreacted water in addition to isopropyl alcohol produced by the reaction of 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 isopropyl ether (DIPE), hexene, 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.

[0041] To this end, the reaction product (101) obtained by the gas phase reaction of the purified propylene and water is supplied to a gas purification unit including an absorption tower (201), a flash drum / gas separation tower (202), and a gas purification tower (203) to separate a gas component including unreacted propylene monomer (S2).

[0042] Specifically, the reaction product (101) is supplied to the lower part of the absorption tower (201), and process circulation water is introduced to the upper part 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 end. 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 upper part. The unreacted propylene monomer included in the gaseous stream (201a) can be recycled to the reaction unit (100).

[0043] 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.

[0044] 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.

[0045] 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%.

[0046] Accordingly, the liquid stream (201b) containing isopropyl alcohol separated from the absorption tower (201) is supplied to one or more flash drums and a gas separation tower (202). In the flash drum, the internal pressure is maintained at 0 to 5 kg / cm 2· g, specifically 0 to 2 kg / cm 2· By reducing the pressure to a range of g, the remaining unreacted propylene contained in the liquid stream can be recovered as a gas and supplied to a gas separation tower. The gas separation tower can be operated at a pressure of 10 to 30 kg / cm 2· g, specifically 10 to 25 kg / cm 2· It can be operated at an internal pressure of g. Through this process, a gaseous upper stream (202a) containing residual unreacted propylene and a liquid lower stream (202b) containing high-boiling-point components such as isopropyl alcohol can be discharged from the flash drum and gas separation tower (202).

[0047] The upper stream (202a) discharged from the flash drum and gas separation tower may contain, in addition to unreacted propylene, inert gases and high-boiling components, including ethane, propane, etc., which are still impurities. For example, the stream (202a) may contain 90 to 98 wt% of unreacted propylene and the remainder of impurities, based on its total weight.

[0048] In order to remove impurities contained in the unreacted propylene, a stream (202a) containing unreacted propylene discharged from the flash drum and gas separation tower is supplied to a gas purification tower (203).

[0049] In the present invention, raw propylene containing impurities is supplied to the gas purification tower (203) and purified together with unreacted propylene. The raw propylene supplied to the gas purification tower may contain 95 to 99.8 wt% of propylene and the remainder of impurities based on its total weight.

[0050] The purity of the above raw material propylene is higher than that of unreacted propylene. Therefore, in terms of separation performance, it is advantageous for the feed port of the raw material propylene in the gas purification tower (203) to be positioned higher than the feed port of unreacted propylene, which contains many impurities such as propane.

[0051] In one embodiment of the present invention, the feed port of the raw propylene may be arranged at a stage corresponding to a height of 25% to 60% from the top of the gas purification tower (203), and the feed port of the stream (202a) containing the unreacted propylene may be arranged at a stage corresponding to a height of 50% to 85% from the top of the gas purification tower (203). When these feed positions are satisfied, purification of raw propylene and unreacted propylene having a high content of impurities such as propane can be efficiently performed simultaneously while minimizing energy consumption.

[0052] In addition, the stream containing the unreacted propylene and the raw propylene can be supplied to the gas purification tower (203) at a flow rate ratio of 0.2:1 to 2:1, specifically 0.4:1 to 1.5:1, and when the flow rate ratio range is satisfied, the efficiency of removing impurities can be increased while minimizing energy consumption.

[0053] The above gas purification tower (203) has a temperature of 40 to 100°C, specifically 40 to 80°C and a pressure of 10 to 30 kg / cm 2· g, specifically 15 to 30 kg / cm 2· It can be operated at a pressure of g, and when these operating conditions are satisfied, it can effectively remove impurities from unreacted propylene and raw propylene while minimizing energy consumption.

[0054] The raw propylene and unreacted propylene purified in the gas purification tower (203) under the above conditions may contain 97 to 99.8 wt% of propylene based on their total weight, and the residual amount of impurities may be less than 3 wt%, and may be recovered as a side stream (203c) and recycled to the reaction unit (100). In addition, a stream (203a) containing light components (e.g., ethane, ethylene) separated in the gas purification tower (203) may be exhausted, and a stream (203b) containing heavy components (e.g., propane, butylene) may be discharged to the bottom.

[0055] Meanwhile, the liquid stream (202b) containing isopropyl alcohol discharged from the flash drum and the lower part of the gas separation tower (202) of the gas purification unit may contain isopropyl alcohol, water, and organic substances such as n-propyl alcohol (NPA), isopropyl ether (DIPE), and hexanol as byproducts.

[0056] Therefore, it is necessary to purify the liquid stream (202b) containing the above isopropyl alcohol into high-purity isopropyl alcohol through an IPA purification unit including an organic matter removal tower (301), a water removal tower (302), an IPA recovery tower (303), a solvent recovery tower (304), and an NPA removal tower (305).

[0057] Specifically, the reaction product from which the gas component is separated, i.e., the bottom stream (202b) discharged from the flash drum / gas separation tower of the gas purification unit, is supplied to the organic matter removal tower (301), and brought into contact with process circulation water to discharge an upper stream (301a) containing organic matter and a bottom stream (301b) containing isopropyl alcohol. At this time, the process circulation water may use water recovered from the distillation tower included in the IPA purification unit at the subsequent stage, i.e., the water removal tower (302), and the process circulation water can selectively dissolve isopropyl alcohol by utilizing the difference in solubility and move it to the lower portion, thereby separating it from organic byproducts.

[0058] In one embodiment of the present invention, the flow rate of the process circulation water supplied to the organic matter removal tower (301) may be 20 to 50 wt% or 25 to 45 wt% of the flow rate of the reaction product. When the process washing water is supplied at a flow rate within the above range, the dissolution rate 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.

[0059] Next, the bottom discharge stream (301b) of the organic matter removal tower 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).

[0060] 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, 80 to 90 wt% of isopropyl alcohol and 10 to 20 wt% of water.

[0061] The water separated into the bottom stream (302b) of the water removal tower (302) can be recovered and used as process circulation water. As described above, the water separated in the water removal tower (302) can be used as process circulation water supplied to the absorption tower (201) and organic matter removal tower (301) of the previous stage. In addition, since the water separated in the water removal tower (302) has a high temperature exceeding 100°C, it can also be used for heat exchange for preheating the water supplied to the reaction unit (100) as needed.

[0062] 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.) is introduced as an azeotrope 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.

[0063] 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).

[0064] Meanwhile, the side discharge stream (302c) of the water removal tower (302) containing n-propyl alcohol (NPA) is supplied to the NPA 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).

[0065] The operating conditions of the distillation columns included in the above IPA purification unit are not particularly limited and can be appropriately selected within a range that is normally applied.

[0066] According to the present invention, since purification of propylene and unreacted propylene used as raw materials in the gas purification step of the isopropyl manufacturing process is performed simultaneously, there is no need to add a separate column for purification of raw material propylene.

[0067] In addition, by supplying raw material propylene to a higher position than unreacted propylene in the gas purification tower, it is possible to efficiently simultaneously purify unreacted propylene and raw material propylene with a high content of impurities such as propane while minimizing energy consumption.

[0068] In this way, by integrating the purification of raw propylene and the purification of unreacted propylene, not only can the equipment costs and operating costs associated with adding a separate column be reduced compared to the existing isopropyl manufacturing process, but energy consumption can also be reduced.

[0069] 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.

[0070] 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.

[0071] Example 1

[0072] As shown in FIGS. 3 and 4, isopropyl alcohol was produced using a system including a reaction unit (100); a gas purification unit (200) including an absorption tower (201), a flash drum / gas separation tower (202), and a gas purification tower (203); and an IPA purification unit (300) including an organic matter removal tower (301), a water removal tower (302), an IPA recovery tower (303), a solvent recovery tower (304), and an NPA removal tower (305).

[0073] (Step 1)

[0074] Water and propylene purified from the gas purification tower (203) at the rear end were supplied to the reaction unit (100) and reacted to obtain a reaction product (101) containing isopropyl alcohol (IPA).

[0075] (Step 2)

[0076] The above reaction product (101) was supplied to the absorption tower (201) of the gas purification unit (200), and the process circulation water recovered from the water removal tower (302) at the rear end was injected into the upper part of the absorption tower (201), and the liquid stream (201b) in which the gaseous IPA was absorbed was discharged to the lower part, and the gaseous stream (201a) containing the unreacted propylene monomer was separated to the upper part and circulated to the reaction unit (100). The absorption tower (201) was operated under a pressure of 33 kg / cm 2· g and the upper / lower temperature was 95℃. The IPA-absorbed liquid stream (201b) was supplied to the flash drum / gas separation tower (202), and the internal pressure of the flash drum was 0.5 kg / cm 2· g and the gas separation tower is pressurized to 20 kg / cm 2· By driving at a pressure of g, a gaseous upper stream (202a) containing residual unreacted propylene and a liquid lower stream (202b) containing IPA were discharged.

[0077] Next, the gaseous stream (202a) containing the unreacted propylene was supplied to the gas purification tower (203), and additionally, raw propylene having a composition as shown in Table 1 was supplied to simultaneously purify unreacted propylene and raw propylene (operating conditions: 27 kg / cm 2· (at a pressure of g, an upper temperature of 45°C, and a lower temperature of 65°C). At this time, a gaseous stream (202a) containing unreacted propylene was supplied at a position 85% from the top of the gas purification tower (203), and raw propylene was supplied at a position 25% from the top, which is a higher position.

[0078] The raw propylene and unreacted propylene purified in the above gas purification tower (203) were recovered as a side stream (203c) and recycled to the reaction unit (100).

[0079] (Step 3)

[0080] A liquid stream (202b) containing isopropyl alcohol discharged from the lower portion of the flash drum and gas separation tower (202) was supplied to the first organic matter removal tower (301) of the IPA purification unit (300), and brought into contact with process circulation water recovered from the water removal tower (302) at the rear, thereby discharging an upper stream (301a) containing organic matter and a lower stream (301b) containing isopropyl alcohol.

[0081] The bottom discharge stream (301b) of the organic matter removal tower is supplied to the water removal tower (302) to separate and discharge an upper stream (302a) containing isopropyl alcohol, a lower stream (302b) containing water, and a side stream containing n-propyl alcohol (NPA), and then the top discharge stream (302a) of the water removal tower (302) is supplied to the IPA recovery tower (303) and cyclohexane is introduced as an azeotrope to discharge an upper stream (303a) containing water and cyclohexane, and IPA is separated from the bottom to obtain the final IPA product.

[0082] Meanwhile, the side discharge stream (302c) of the water removal tower (302) containing n-propyl alcohol (NPA) was supplied to the NPA 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).

[0083] Composition of raw material propylene: Ethane 0.05 wt%, Propane 0.45 wt%, Propylene 99.2 wt%, Others: Ethylene 10 ppm, Butane 5 ppm, Butylene 5 ppm, etc.

[0084]

[0085] Example 2

[0086] In the above step 2, the gaseous stream (202a) containing unreacted propylene was supplied at a position 65% from the top of the gas purification tower (203), and the same process as Example 1 was performed, except that the raw propylene was supplied at a position 45% from the top, which is a higher position.

[0087]

[0088] Example 3

[0089] In the above step 2, the gaseous stream (202a) containing unreacted propylene was supplied at a position 45% from the top of the gas purification tower (203), and the same process as Example 1 was performed, except that the raw propylene was supplied at a position 65% from the top, which is a lower position.

[0090]

[0091] Example 4

[0092] In the above step 2, the gaseous stream (202a) containing unreacted propylene was supplied at a position 25% from the top of the gas purification tower (203), and the same process as Example 1 was performed, except that the raw propylene was supplied at a position 85% from the top, which is a lower position.

[0093]

[0094] Comparative Example 1

[0095] (Step 1)

[0096] Water and raw material propylene of the composition shown in Table 1 were supplied to the reaction unit (100) and reacted to obtain a reaction product containing IPA, product (101).

[0097] (Step 2)

[0098] The above reaction product (101) was supplied to the absorption tower (201) of the gas purification unit (200), and the process circulation water recovered from the water removal tower (302) at the rear end was injected into the upper part of the absorption tower (201), and the liquid stream (201b) in which the gaseous IPA was absorbed was discharged to the lower part, and the gaseous stream (201a) containing the unreacted propylene monomer was separated to the upper part and circulated to the reaction unit (100). The absorption tower (201) was operated under a pressure of 33 kg / cm 2· g and the upper / lower temperature was 95℃. The IPA-absorbed liquid stream (201b) was supplied to the flash drum / gas separation tower (202), and the internal pressure of the flash drum was 0.5 kg / cm 2· g and the gas separation tower is pressurized to 20 kg / cm 2· By driving at a pressure of g, a gaseous upper stream (202a) containing residual unreacted propylene and a liquid lower stream (202b) containing IPA were discharged.

[0099] Next, the gaseous stream (202a) containing the unreacted propylene is supplied to a gas purification tower (203) to purify the unreacted propylene (operating conditions: 27 kg / cm 2· (at a pressure of g, an upper temperature of 45°C and a lower temperature of 65°C) was recovered as a side stream (203c) containing the purified unreacted propylene and recycled to the reaction section (100).

[0100] (Step 3)

[0101] The same process as step 3 of Example 1 was performed.

[0102]

[0103] Comparative Example 2

[0104] (Step 1)

[0105] A raw material purification unit (10) including two columns was installed in front of the reaction unit (100), and raw material propylene of the composition shown in Table 1 was supplied and purified (operating conditions of the first column: 22 kg / cm 2· Pressure of g, upper temperature of 45℃ and lower temperature of 52℃; operating conditions of the second column: 24kg / cm 2· (pressure of g, upper temperature of 52℃ and lower temperature of 62℃).

[0106] Next, water and propylene purified in the raw material purification unit (10) were supplied to the reaction unit (100) and reacted to obtain a reaction product containing IPA, product (101).

[0107] (Step 2)

[0108] The above reaction product (101) was supplied to the absorption tower (201) of the gas purification unit (200), and the process circulation water recovered from the water removal tower (302) at the rear end was injected into the upper part of the absorption tower (201), and the liquid stream (201b) in which the gaseous IPA was absorbed was discharged to the lower part, and the gaseous stream (201a) containing the unreacted propylene monomer was separated to the upper part and circulated to the reaction unit (100). The absorption tower (201) was operated under a pressure of 33 kg / cm 2· g and the upper / lower temperature was 95℃. The IPA-absorbed liquid stream (201b) was supplied to the flash drum / gas separation tower (202), and the internal pressure of the flash drum was 0.5 kg / cm 2· g and the gas separation tower is pressurized to 20 kg / cm 2· By driving at a pressure of g, a gaseous upper stream (202a) containing residual unreacted propylene and a liquid lower stream (202b) containing IPA were discharged.

[0109] Next, the gaseous stream (202a) containing the unreacted propylene is supplied to a gas purification tower (203) to purify the unreacted propylene (operating conditions: 27 kg / cm 2· (at a pressure of g, an upper temperature of 45°C and a lower temperature of 65°C) was recovered as a side stream (203c) containing the purified unreacted propylene and recycled to the reaction section (100).

[0110] (Step 3)

[0111] The same process as step 3 of Example 1 was performed.

[0112]

[0113] Table 2 below compares the IPA manufacturing process and results according to examples and comparative examples.

[0114] Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Refining of raw material propylene - Raw material Refining gas Purification tower gas Purification tower gas Purification tower gas Purification tower gas Supply location of raw material and unreacted propylene in the purification tower 1) --25% / 85%45% / 65%65%45%85% / 25%Total energy consumed in refining raw material and unreacted propylene 2) 0.3410.930.451.572.32Composition of propylene recovered from the gas purification tower (wt%)Ethane1.070.190.190.190.190.19Propylene94.0597.8197.8197.8197.8197.81Propane4.882.002.002.002.002.00Concentration of impurities (ethanol, butanol, etc.) in IPA product6.4ppm0.8ppm0.8ppm0.8ppm0.8ppm0.8ppm0.8ppm1) The supply position in the gas purification tower (203) was set based on the height from the top (0%) to the bottom (100%).2) The energy consumption was simulated based on the composition of the upper stream (203c) discharged from the gas purification tower of Comparative Example 2, and then the raw material and unreacted gas were calculated accordingly. The total energy consumed in the purification of propylene was calculated.

[0115] In the above Table 2, it can be confirmed that Examples 1 to 4, in which simultaneous purification of raw material propylene and unreacted propylene was performed in a gas purification tower during the IPA manufacturing process, reduced the concentration of impurities in the propylene recovered from the gas purification tower and the final IPA product obtained. In particular, Examples 1 and 2, in which raw material propylene was supplied at a higher position than unreacted propylene in the gas purification tower (203), i.e., at a position close to the top, were advantageous in separation performance and thus drastically reduced energy consumption. On the other hand, Examples 3 and 4, in which raw material propylene was supplied at a lower position than unreacted propylene, i.e., the supply positions of raw material propylene and unreacted propylene in the gas purification tower were not appropriate, resulting in high energy consumption.

[0116] In Comparative Example 1, since raw propylene was fed into the reaction unit (100) without purification, the energy consumption was low, but the concentration of impurities in the propylene recovered from the gas purification tower (203) and the final IPA product was high due to impurities contained in the raw propylene. Therefore, it is difficult to utilize it as a high-purity IPA product.

[0117] Comparative Example 2 purified raw material propylene in a separate raw material purification unit (10) and then fed into the reaction unit (100), thereby lowering the concentration of impurities in the propylene recovered from the gas purification tower and the final IPA product obtained. However, since the number of columns required for the raw material purification unit (10) and the gas purification tower (203) increased to three, there was a disadvantage in that the installation cost and operating cost increased compared to the examples in which simultaneous purification of raw material propylene and unreacted propylene was performed in the gas purification tower (203). In addition, it was disadvantageous compared to Examples 1 and 2 in which the supply locations of raw material propylene and unreacted propylene were optimized in terms of energy consumption.

[0118]

[0119] [Explanation of symbols]

[0120] 10: Raw Material Refining Department

[0121] 100: Reaction section

[0122] 200: Gas Purification Unit

[0123] 201: Absorption tower

[0124] 202: Flash drum / gas separation tower

[0125] 203: Gas purification tower

[0126] 300: IPA purification unit

[0127] 301: Organic Removal Tower

[0128] 302: Water removal tower

[0129] 303: IPA recovery tower

[0130] 304: Solvent recovery tower

[0131] 305: NPA Removal Tower

Claims

1. (S1) A step of reacting propylene and water in a reaction section to obtain a reaction product containing isopropyl alcohol (IPA); (S2) a step of supplying the above reaction product to a gas purification unit to separate a gas component including unreacted propylene; and (S3) A step of supplying the reaction product from which the above gas component is separated to an IPA purification unit to obtain purified isopropyl alcohol, A method for producing isopropyl alcohol by additionally supplying raw material propylene to the above gas purification unit to purify raw material propylene and unreacted propylene.

2. In paragraph 1, The above gas purification unit includes an absorption tower, a flash drum, a gas separation tower, and a gas purification tower, The reaction product supplied from the bottom of the absorption tower is brought into contact with the process circulation water supplied from the top, thereby discharging a gaseous upper stream containing unreacted propylene and a liquid lower stream containing components absorbed in the process circulation water. The bottom discharge stream of the absorption column is supplied to the flash drum and gas separation tower to discharge a gaseous top stream containing residual unreacted propylene and a liquid bottom stream containing isopropyl alcohol, The gaseous stream containing unreacted propylene discharged from the flash drum and gas separation tower and the raw propylene are supplied to the gas purification tower, and the side stream of purified propylene and the bottom stream of high-boiling-point components are discharged while the gas of low-boiling-point components is exhausted to the upper portion. A method for producing isopropyl alcohol by supplying purified propylene separated from the above gas purification tower to a reaction unit.

3. In paragraph 2, A method for producing isopropyl alcohol in which raw material propylene is supplied to a higher position than unreacted propylene in the above gas purification tower.

4. In paragraph 2, The feed port of the above raw material propylene is fed at a height of 25% to 60% from the top of the gas purification tower, A method for producing isopropyl alcohol, wherein the stream containing the unreacted propylene is supplied at a height of 50% to 85% from the top of the gas purification tower.

5. In paragraph 2, A method for producing isopropyl alcohol, wherein the stream containing the unreacted propylene and the raw material propylene are supplied at a flow rate ratio of 0.2:1 to 2:

1.

6. In paragraph 2, The above gas purification tower has a temperature of 40 to 100 ℃ and a pressure of 10 to 30 kg / cm 2· A method for producing isopropyl alcohol operated at a pressure of g.

7. In paragraph 2, A method for producing isopropyl alcohol, wherein the raw propylene supplied to the gas purification tower contains 95 to 99.8 wt% of propylene based on the total weight thereof.

8. In paragraph 2, A method for producing isopropyl alcohol, wherein the raw propylene and unreacted propylene purified in the above gas purification tower contain 97 to 99.8 wt% of propylene based on the total weight thereof.

9. In paragraph 2, A method for producing isopropyl alcohol, wherein the low-boiling-point component gas exhausted from the above gas purification tower contains ethane, ethylene, and a mixture thereof.

10. In paragraph 1, The above IPA purification unit includes an organic matter removal tower, a water removal tower, an IPA recovery tower, an n-propyl alcohol removal tower, and a solvent recovery tower. The liquid stream discharged from the flash drum and gas separation tower of the gas purification unit is supplied to the organic matter removal tower and brought into contact with process circulation water to discharge an upper stream containing organic matter and a lower stream containing isopropyl alcohol. The bottom discharge stream of the organic matter removal tower is supplied from the water removal tower and discharged 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). Supplying the upper discharge stream of the water removal tower and the organic solvent to the IPA recovery tower to discharge an upper stream containing water and an organic solvent and a lower stream containing IPA, The upper discharge stream of the IPA separation tower is supplied to the solvent recovery tower to discharge the upper stream of solvent and the lower stream of water. A method for producing isopropyl alcohol, comprising supplying a side discharge stream of the water removal tower to the NPA removal tower and discharging a stream containing NPA downward.

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