Method for producing isopropyl alcohol

Abstract

The present invention provides a method for producing isopropyl alcohol (IPA), the method comprising: (S1) reacting propylene and water in a reaction section to obtain a reaction product containing isopropyl alcohol (IPA); (S2) supplying the reaction product to a gas purification section to separate gas components containing unreacted propylene; and (S3) supplying the reaction product from which the gas components have been separated to an IPA purification section to obtain purified isopropyl alcohol, wherein raw material propylene can be further supplied to the gas purification section to purify the raw material propylene and unreacted propylene.

Description

[Technical Field]

[0001] This application claims priority rights under Korean Patent Application No. 10-2023-0119564 dated September 8, 2023, and Korean Patent Application No. 10-2024-0085390 dated June 28, 2024, and all content disclosed in the documents of the said Korean patent applications is incorporated herein by reference.

[0002] The present invention relates to a method for producing isopropyl alcohol, and more particularly to a method for producing high-purity isopropyl alcohol by purifying propylene used as a raw material together with unreacted propylene. [Background technology]

[0003] Isopropyl alcohol (IPA) is used in a variety of applications in the electronics industry, including semiconductor and LCD (liquid crystal display) manufacturing, as a cleaning agent, industrial paint and reagent raw material, and solvent for paints and inks.

[0004] Such isopropyl alcohol can be produced by reacting propylene (C3H6) with water. Typically, as shown in Figure 1, isopropyl alcohol is produced by reacting propylene monomer with water in a reaction unit 100 to obtain a reaction product containing IPA, unreacted propylene monomer, unreacted water, n-propyl alcohol (NPA), and by-products such as organic matter. The reaction product is then transferred to a gas purification unit 200, where unreacted propylene monomer and other low-boiling point gas components are separated. The reaction product from which the gas components have been separated is then supplied to an IPA purification unit 300 containing numerous distillation columns, where organic matter, NPA, and water are removed to obtain the crude isopropyl alcohol product.

[0005] The propylene (C3H6) supplied as a raw material to the reaction chamber is preferably of high purity. If the propylene contains impurities such as unsaturated hydrocarbons like ethylene, butene, and pentene, a by-product (e.g., ethanol) with a boiling point similar to that of IPA may be produced during the reaction between propylene and water. In addition, the raw material propylene may already contain impurities such as ethanol and n-propyl alcohol (NPA) with boiling points similar to that of IPA.

[0006] Therefore, purification of the raw material propylene is necessary to obtain high-purity IPA. As shown in Figure 2, in existing IPA manufacturing processes, a raw material purification unit 10 containing two columns is installed before the reaction unit to remove impurities contained in the raw material propylene.

[0007] However, when operating an IPA manufacturing system equipped with a raw material purification unit to control the quality of the raw material propylene, not only does the energy consumption increase due to the use of steam, but the equipment costs and operating costs also increase due to the addition of columns. [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention aims to solve the problems mentioned in the background art of the above invention, and relates to a method for producing high-purity isopropyl alcohol by purifying propylene used as a raw material together with unreacted propylene. [Means for solving the problem]

[0009] According to one aspect of the present invention for solving the above problems, (S1) A step of reacting propylene and water in a reaction chamber to obtain a reaction product containing isopropyl alcohol (IPA), (S2) The step of supplying the reaction product to a gas purification unit to separate the gas component containing unreacted propylene, (S3) The step of supplying the reaction product from which the gas component has been separated to an IPA purification unit to obtain purified isopropyl alcohol, A method for producing isopropyl alcohol is provided, which involves further supplying raw material propylene to the gas purification section to purify the raw material propylene and unreacted propylene.

[0010] In the present invention, the raw material propylene can be supplied to a position higher than the unreacted propylene in the gas purification tower. [Effects of the Invention]

[0011] According to the present invention, by simultaneously purifying propylene and unreacted propylene used as raw materials in the gas purification step of the isopropyl alcohol production process, there is no need to add a separate column for purifying the raw material propylene.

[0012] Furthermore, by supplying the raw material propylene to a position higher than the unreacted propylene in the gas purification tower, energy consumption can be minimized, and the purification of unreacted propylene, which contains a high amount of impurities such as propane, and the raw material propylene can be performed efficiently and simultaneously.

[0013] In this way, by integrating the purification of raw material propylene and the purification of unreacted propylene, it is possible to reduce not only the equipment and operating costs associated with adding another column compared to the existing isopropyl alcohol production process, but also energy consumption. [Brief explanation of the drawing]

[0014] [Figure 1] This diagram schematically shows the typical manufacturing process for isopropyl alcohol. [Figure 2] This diagram schematically shows a conventional isopropyl alcohol manufacturing process in which the raw material propylene is purified separately. [Figure 3]It is a diagram schematically showing a process for producing isopropyl alcohol that integrates purification of raw material propylene and purification of unreacted propylene according to an embodiment of the present invention. [Figure 4] It is a diagram more specifically illustrating the process of FIG. 3 MODE FOR CARRYING OUT THE INVENTION

[0015] Terms and words used in the description and claims of the present invention should not be construed as being limited to their ordinary or dictionary meanings, and should be interpreted into meanings and concepts consistent with the technical idea of the present invention in accordance with the principle that inventors can appropriately define the concept of terms in order to describe their invention in the best manner.

[0016] The meaning of "comprising" or "containing" as used herein is to specify a particular feature, region, constant, step, act, element or component, and does not exclude the addition of other particular features, regions, constants, steps, acts, elements or components.

[0017] As used herein, the term "stream" may refer to the flow of a fluid in a process, and may also refer to the fluid itself flowing in a pipe. Specifically, the stream may refer to both the fluid itself flowing in a pipe connecting each device and the flow of the fluid. In addition, the fluid may contain one or more components selected from gas, liquid and solid.

[0018] As used herein, the term "upper portion" means a point at a height of 0 to 20% downward from the top of a device, and may specifically mean the uppermost part (column top), unless otherwise specified. In addition, the term "lower portion" means a point at a height of 80 to 100% downward from the top of a device, and may specifically mean the lowermost part (column bottom).

[0019] As used in this application, the term "side stream" may mean, unless otherwise specified, a stream discharged from the top of the device downwards at a height of 10-80% or 10-70%.

[0020] Furthermore, the term "pressure" as used in this application refers to gauge pressure measured relative to atmospheric pressure.

[0021] On the other hand, 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 upper or lower temperature of the device unless otherwise specified. Also, the operating pressure of the device may refer to the upper pressure of the device unless otherwise specified.

[0022] One embodiment of the present invention relates to a method for producing isopropyl alcohol (IPA), and the method for producing IPA according to the present invention will be described in detail below with reference to the drawings.

[0023] Figure 3 is a schematic diagram illustrating the isopropyl alcohol production process, which integrates the purification of raw material propylene and the purification of unreacted propylene according to one embodiment of the present invention.

[0024] Referring to Figure 3, the method for producing isopropyl alcohol according to the present invention comprises a reaction step of propylene and water in a reaction section 100 (S1), a purification step of unreacted propylene in a gas purification section 200 (S2), and a step of obtaining high-purity IPA in an IPA purification section 300 (S3), characterized in that raw material propylene is supplied to the gas purification section and purified together with unreacted propylene before being supplied to the reaction step.

[0025] Figure 4 is a diagram illustrating more specifically the isopropyl alcohol production process according to one embodiment of the present invention. Isopropyl alcohol can be produced using a system comprising a reaction section 100, a gas purification section including an absorption tower 201, a flash drum / gas separation tower 202, and a gas purification tower 203, and an IPA purification section 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. Furthermore, the system can be used with the addition of a reboiler for transferring heat to the supply streams of each tower for heating, a condenser for converting the upper stream generated by the heating from the gas phase to the liquid phase, a decanter for liquid-liquid separation of the condensed stream, valves and pumps for controlling the flow of the stream, etc.

[0026] First, in the reaction unit 100, a reaction product 101 containing isopropyl alcohol can be obtained by a gas-phase reaction between propylene monomer and water.

[0027] The propylene (C3H6) supplied as a raw material to the reaction section 100 is preferably of high purity. If the propylene contains impurities such as other unsaturated hydrocarbons like ethylene, butene, and pentene, as well as ethane, propane, and carbon dioxide, a by-product (e.g., ethanol) with a boiling point similar to that of IPA may be produced during the reaction between propylene and water.

[0028] Therefore, in order to obtain high-purity IPA, purification of the raw material propylene is necessary. In this invention, the raw material propylene is purified in a gas purification unit located downstream of the reaction unit 100, specifically in a gas purification column 203, to remove impurities, and then supplied to the reaction unit 100.

[0029] In one embodiment of the present invention, the purified propylene supplied to the reaction unit 100 preferably contains 97% by weight or more of propylene, for example, 97 to 99.8% by weight, and has an impurity content of less than 3% by weight.

[0030] On the other hand, only a portion of the purified propylene supplied to the reaction unit 100 is used in the reaction. Therefore, the reaction product may contain 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 contain 65-85% by weight of unreacted propylene monomer, 4-8% by weight of isopropyl alcohol, and 5-30% by weight of water. Furthermore, the reaction product may contain by-products such as diisopropyl ether (DIPE), hexene, acetone, and n-propyl alcohol (NPA). Therefore, it is necessary to separate the unreacted raw materials from the reaction product and purify the isopropyl alcohol from the various by-products.

[0031] For this purpose, the reaction product 101 obtained by the gas-phase reaction of the purified propylene and water is supplied to a gas purification section including an absorption tower 201, a flash drum / gas separation tower 202, and a gas purification tower 203 to separate the gas component containing unreacted propylene monomer (S2).

[0032] Specifically, the reaction product 101 is supplied to the lower stage of the absorption tower 201, and process circulating water is introduced to the upper stage of the absorption tower 201 to separate the unreacted propylene monomer. Here, the process circulating water can be water recovered from the distillation tower, i.e., the water removal tower 302, which is included in the subsequent IPA purification section. In the absorption tower 201, the gaseous isopropyl alcohol contained in the reaction product is absorbed by the process circulating water and obtained as the lower liquid phase stream 201b, and in the upper stage, the gaseous phase stream 201a containing the unreacted propylene monomer can be separated. The unreacted propylene monomer contained in the gaseous phase stream 201a can be recycled back to the reaction section 100.

[0033] In one embodiment of the present invention, the flow rate of the process circulating water supplied to the absorption tower 201 can be 15 to 40% by weight or 15 to 35% by weight of the flow rate of the reaction product. When the process circulating water is supplied at a flow rate within this range, the absorption capacity of isopropyl alcohol contained in the reaction product can be improved, and the energy costs for recovering the process circulating water in the subsequent stages can be prevented from increasing excessively.

[0034] The absorption tower 201 operates at a temperature of 90-100°C or 90-95°C and an absorption rate of 25-40 kg / cm³. 2 ·g or 25-35kg / cm³ 2 It can be operated at a pressure of 1.5g. When the above operating conditions are met, the upper discharge stream containing unreacted propylene monomer and the lower discharge stream containing isopropyl alcohol can be effectively separated.

[0035] On the other hand, the lower liquid phase stream of the absorption tower 201 may contain small amounts 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 unreacted propylene monomers and other low-boiling point gas components in the lower liquid phase stream of the absorption tower 201 may be 5% by weight or less, or in the range of 2 to 5% by weight.

[0036] This allows the liquid phase stream 201b containing isopropyl alcohol separated in the absorption tower 201 to be supplied to one or more flash drums and gas separation towers 202. In the flash drum, the internal pressure is set to 0-5 kg / cm². 2 • g, in detail 0-2 kg / cm³ 2 The pressure can be reduced to a range of 0.5g, allowing the remaining unreacted propylene contained in the liquid phase stream to be recovered as a gas and supplied to a gas separation tower. The gas separation tower can handle a pressure of 10-30 kg / cm³. 2 • g, specifically 10-25 kg / cm³ 2It can be operated at an internal pressure of g. This process allows for the discharge of the upper stream 202a of the gas phase containing unreacted propylene remaining in the flash drum and gas separation column 202, and the lower stream 202b of the liquid phase containing high-boiling point components such as isopropyl alcohol.

[0037] The upper stream 202a discharged from the flash drum and gas separation tower may still contain inert gases, such as ethane and propane, and high-boiling-point components, in addition to unreacted propylene. For example, the stream 202a may contain 90-98% by weight of unreacted propylene and the remaining amount of impurities based on its total weight.

[0038] To remove impurities contained in the unreacted propylene, stream 202a containing the unreacted propylene discharged from the flash drum and gas separation tower is supplied to the gas purification tower 203.

[0039] In this invention, raw material propylene containing impurities is supplied to the gas purification column 203 and purified together with unreacted propylene. The raw material propylene supplied to the gas purification column may contain 95 to 99.8% by weight of propylene and the remaining impurities, based on its total weight.

[0040] The purity of the raw material propylene is higher than that of the unreacted propylene. Therefore, in terms of separation performance, it is advantageous for the gas purification column 203 to position the feed port for the raw material propylene higher than the feed port for the unreacted propylene, which contains many impurities such as propane.

[0041] In one embodiment of the present invention, the supply port for the raw material propylene can be located at a stage corresponding to a height of 25% to 60% from the top of the gas purification tower 203, and the supply port for the stream 202a containing the unreacted propylene can be located at a stage corresponding to a height of 50% to 85% from the top of the gas purification tower 203. By filling the supply positions in this manner, energy consumption can be minimized, and the purification of unreacted propylene and raw material propylene, which have a high content of impurities such as propane, can be efficiently performed simultaneously.

[0042] Furthermore, the stream containing the unreacted propylene and the raw material propylene can be supplied to the gas purification column 203 at a flow rate ratio of 0.2:1 to 2:1, specifically 0.4:1 to 1.5:1. By satisfying this range of flow rate ratios, energy consumption can be minimized and the efficiency of impurity removal can be increased.

[0043] The gas purification tower 203 operates at a temperature of 40-100°C, specifically 40-80°C, and a flow rate of 10-30 kg / cm³. 2 g, in detail 15-30 kg / cm³ 2 It can be operated at a pressure of 1g, and under these operating conditions, energy consumption can be minimized while effectively removing impurities from unreacted propylene and raw material propylene.

[0044] Under the conditions described above, the raw material propylene and unreacted propylene purified in the gas purification tower 203 can contain 97-99.8% by weight of propylene relative to their total weight, with a residual amount of impurities of less than 3% by weight, and can be recovered as side stream 203c and recycled to the reaction section 100. In addition, stream 203a containing lighter components (e.g., ethane, ethylene) separated in the gas purification tower 203 can be exhausted, and stream 203b containing heavier components (e.g., propane, butylene) can be discharged to the bottom.

[0045] On the other hand, the liquid phase stream 202b containing isopropyl alcohol discharged from the flash drum of the gas purification unit and the lower part of the gas separation tower 202 may contain isopropyl alcohol, water, and by-products such as organic substances like n-propyl alcohol (NPA), diisopropyl ether (DIPE), and hexanol.

[0046] Therefore, the liquid-phase stream 202b containing isopropyl alcohol needs to be purified to high-purity isopropyl alcohol by passing through an IPA purification section which includes 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.

[0047] Specifically, the reaction product from which the gaseous components have been separated, i.e., the lower stream 202b discharged from the flash drum / gas separation tower of the gas purification section, is supplied to the organic matter removal tower 301. There, it comes into contact with the process circulating water, and the upper stream 301a containing organic matter and the lower stream 301b containing isopropyl alcohol can be discharged. Here, the process circulating water can be water recovered in the distillation tower included in the subsequent IPA purification section, i.e., water recovered in the water removal tower 302. The process circulating water selectively dissolves the isopropyl alcohol using the difference in solubility and moves to the lower section, where it can be separated from the organic by-products.

[0048] In one embodiment of the present invention, the flow rate of the process circulating water supplied to the organic matter removal tower 301 may be 20-50% by weight or 25-45% by weight of the flow rate of the reaction product. When the process circulating water is supplied at a flow rate within the above range, the dissolution rate of isopropyl alcohol contained in the reaction product can be improved, and the energy costs for recovering the process circulating water in the subsequent stages can be prevented from increasing excessively.

[0049] Next, the lower discharge stream 301b of the organic matter removal tower is supplied to the water removal tower 302, separating and discharging the upper stream 302a containing isopropyl alcohol, the lower stream 302b containing water, and the side stream containing n-propyl alcohol (NPA).

[0050] The upper stream 302a separated in the water removal tower 302 contains an azeotropic mixture of isopropyl alcohol and water, and may contain, for example, 80-90% by weight of isopropyl alcohol and 10-20% by weight of water.

[0051] The water separated as the lower stream 302b of the water removal tower 302 can be recovered and used as process circulating water. As mentioned above, the water separated in the water removal tower 302 can be used as process circulating water supplied to the preceding absorption tower 201 and organic matter removal tower 301. Furthermore, since the water separated in the water removal tower 302 is at a high temperature exceeding 100°C, it can also be used for heat exchange to preheat the water supplied to the reaction section 100, if necessary.

[0052] Subsequently, 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 added as an azeotrope to discharge the upper stream 303a containing water and organic solvent, and the 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, making it possible to obtain highly purified isopropyl alcohol.

[0053] The water and organic solvent separated at the top of the IPA recovery tower are supplied to the solvent recovery tower 304 via stream 303a, where they are separated into an upper stream 304a of solvent and a lower stream 304b of water, which can then be discharged. The solvent stream 304 can be recycled back to the IPA recovery tower 303.

[0054] On the other hand, the side discharge stream 302c of the water removal tower 302, which contains n-propyl alcohol (NPA), is supplied to the NPA removal tower 305, and the stream 305b containing NPA is discharged to the bottom, and the upper stream 305a can also be recirculated to the water removal tower 302.

[0055] The operating conditions of the distillation column included in the IPA purification section are not particularly limited and can be appropriately selected within the range that is normally applicable.

[0056] According to the present invention, by simultaneously purifying propylene and unreacted propylene used as raw materials in the gas purification step of the isopropyl alcohol production process, there is no need to add a separate column for purifying the raw material propylene.

[0057] Furthermore, by supplying the raw material propylene to a higher position than the unreacted propylene in the gas purification tower, energy consumption can be minimized, and the purification of unreacted propylene, which contains a high amount of impurities such as propane, and the raw material propylene can be performed efficiently at the same time.

[0058] In this way, by integrating the purification of raw material propylene and the purification of unreacted propylene, it is possible to reduce not only the equipment and operating costs associated with adding another column compared to the existing isopropyl alcohol production process, but also energy consumption.

[0059] The present invention will be described in more detail below with reference to examples. However, the following examples are for illustrative purposes only, and it will be obvious to an ordinary person that various changes and modifications are possible within the scope of the present invention and the technical concept, and the scope of the present invention is not limited to these examples alone.

[0060] The following examples and comparative examples simulate the method according to the present invention using the commercial process simulation program AspenPlus. The constants required for the simulation were values ​​built into the program, values ​​described in the literature, etc.

[0061] Example 1 As shown in FIG. 3 and FIG. 4, isopropyl alcohol was produced using a system comprising a reaction section 100, a gas purification section 200 comprising an absorption tower 201, a flash drum / gas separation tower 202 and a gas purification tower 203, and an IPA purification section 300 comprising 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.

[0062] (Step 1) Water and propylene purified in the downstream gas purification tower 203 were supplied to the reaction section 100 and reacted to obtain a reaction product 101 containing isopropyl alcohol (IPA).

[0063] (Step 2) The reaction product 101 is supplied to the absorption tower 201 of the gas purification section 200, process circulating water recovered in the downstream water removal tower 302 is introduced into the upper part of the absorption tower 201, a liquid phase stream 201b with gaseous IPA absorbed therein is discharged from the lower part, and a gas phase stream 201a containing unreacted propylene monomer is separated at the upper part and circulated to the reaction section 100. The absorption tower 201 has a pressure of 33kg / cm 2 ·g and was operated under the condition of an upper / lower temperature of 95°C. The IPA-absorbed liquid phase stream 201b was supplied to a flash drum / gas separation tower 202, and the internal pressure of the flash drum was adjusted to 0.5kg / cm 2 ·g by reducing pressure, the gas separation tower was operated at a pressure of 20kg / cm 2 ·g, and a gas phase upper stream 202a containing remaining unreacted propylene and a liquid phase lower stream 202b containing IPA were discharged.

[0064] Then, the gas phase stream 202a containing unreacted propylene was supplied to the gas purification tower 203, and raw material propylene having a composition as shown in Table 1 below was further supplied to purify unreacted propylene and raw material propylene simultaneously (operating conditions: 27kg / cm 2(G pressure, upper temperature of 45°C and lower temperature of 65°C). Here, a gas phase stream 202a containing unreacted propylene was supplied to the 85% position from the top of the gas purification column 203, and the raw material propylene was supplied to the 25% position from the top, which is higher than that position.

[0065] The raw material propylene and unreacted propylene purified in the gas purification tower 203 were recovered as a side stream 203c and recycled back to the reaction section 100.

[0066] (Step 3) The liquid phase stream 202b containing isopropyl alcohol discharged from the flash drum and the lower part of the gas separation tower 202 was supplied to the organic matter removal tower 301 of the IPA purification unit 300, where it was brought into contact with the process circulating water recovered in the downstream water removal tower 302, and the upper stream 301a containing organic matter and the lower stream 301b containing isopropyl alcohol were discharged.

[0067] The lower discharge stream 301b of the organic matter removal tower was supplied to the water removal tower 302, where the upper stream 302a containing isopropyl alcohol, the lower stream 302b containing water, and the side stream containing n-propyl alcohol (NPA) were separated and discharged. Then, the upper discharge stream 302a of the water removal tower 302 was supplied to the IPA recovery tower 303, where cyclohexane was added as an azeotrope and discharged as the upper stream 303a containing water and cyclohexane. IPA was separated from the lower stream and obtained as the final IPA product.

[0068] 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 downwards, while the upper stream 305a was recirculated back to the water removal tower 302.

[0069] [Table 1]

[0070] Example 2 In step 2, the same process as in Example 1 was carried out, except that a gas phase stream 202a containing unreacted propylene was supplied at a position 65% from the top of the gas purification tower 203, and raw material propylene was supplied at a higher position, 45% from the top.

[0071] Example 3 In step 2, the same process as in Example 1 was carried out, except that a gas phase stream 202a containing unreacted propylene was supplied at a position 45% from the top of the gas purification tower 203, and raw material propylene was supplied at a lower position, at 65% from the top.

[0072] Example 4 In step 2, the same process as in Example 1 was carried out, except that a gas phase stream 202a containing unreacted propylene was supplied at a position 25% from the top of the gas purification tower 203, and raw material propylene was supplied at a lower position, at 85% from the top.

[0073] Comparative Example 1 (Step 1) Water and propylene raw material with the composition shown in Table 1 were supplied to the reaction section 100 and reacted to obtain a reaction product 101 containing IPA.

[0074] (Step 2) The reaction product 101 was supplied to the absorption tower 201 of the gas purification unit 200. Process circulating water recovered in the downstream water removal tower 302 was introduced into the upper part of the absorption tower 201, and the liquid phase stream 201b, from which the gas phase IPA had been absorbed, was discharged to the bottom. The gas phase stream 201a, containing unreacted propylene monomer, was separated to the top and circulated to the reaction unit 100. The absorption tower 201 was operated at a pressure of 33 kg / cm². 2 The system was operated under conditions of -g and upper / lower temperatures of 95°C. The IPA-absorbed liquid phase stream 201b was supplied to the flash drum / gas separation tower 202, and the internal pressure of the flash drum was set to 0.5 kg / cm². 2 The pressure is reduced to g, and the gas separation tower is 20 kg / cm³. 2The system was operated at a pressure of 1 / g to discharge the upper stream 202a of the gas phase containing residual unreacted propylene and the lower stream 202b of the liquid phase containing IPA.

[0075] Next, the gas phase stream 202a containing the unreacted propylene is supplied to the gas purification tower 203 to purify the unreacted propylene (operating conditions: 27 kg / cm³). 2 At a pressure of 0.5g, an upper temperature of 45°C, and a lower temperature of 65°C, the purified unreacted propylene was collected as a side stream 203c and recycled back to the reaction section 100.

[0076] (Step 3) The same process as in Step 3 of Example 1 was followed.

[0077] Comparative Example 2 (Step 1) A raw material purification unit 10 containing two columns was installed upstream of the reaction unit 100, and raw material propylene with the composition shown in Table 1 was supplied and purified (operating conditions for the first column: 22 kg / cm³). 2 •g pressure, upper temperature of 45°C and lower temperature of 52°C; operating conditions for the second column: 24 kg / cm² 2 (G pressure, upper temperature of 52°C, and lower temperature of 62°C).

[0078] 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 101 containing IPA.

[0079] (Step 2) The reaction product 101 was supplied to the absorption tower 201 of the gas purification unit 200. Process circulating water recovered in the downstream water removal tower 302 was introduced into the upper part of the absorption tower 201, and the liquid phase stream 201b, from which the gas phase IPA had been absorbed, was discharged to the bottom. The gas phase stream 201a, containing unreacted propylene monomer, was separated to the top and circulated to the reaction unit 100. The absorption tower 201 was operated at a pressure of 33 kg / cm². 2The system was operated under conditions of -g and upper / lower temperatures of 95°C. The IPA-absorbed liquid phase stream 201b was supplied to the flash drum / gas separation tower 202, and the internal pressure of the flash drum was set to 0.5 kg / cm². 2 The pressure is reduced to g, and the gas separation tower is 20 kg / cm³. 2 The system was operated at a pressure of 1 / g to discharge the upper stream 202a of the gas phase containing residual unreacted propylene and the lower stream 202b of the liquid phase containing IPA.

[0080] Next, the gas phase stream 202a containing the unreacted propylene is supplied to the gas purification tower 203 to purify the unreacted propylene (operating conditions: 27 kg / cm³). 2 At a pressure of 0.5g, an upper temperature of 45°C, and a lower temperature of 65°C, the purified unreacted propylene was collected as a side stream 203c and recycled back to the reaction section 100.

[0081] (Step 3) The same process as in Step 3 of Example 1 was followed.

[0082] Table 2 below compares the manufacturing process and results of IPA using examples and comparative examples.

[0083] [Table 2]

[0084] In Table 2 above, it can be confirmed that in Examples 1 to 4, where raw material propylene and unreacted propylene were simultaneously purified in a gas purification column during the IPA manufacturing process, the concentration of impurities in the propylene recovered in the gas purification column and in the final obtained IPA product was reduced.

[0085] In particular, Examples 1 and 2, in which the raw material propylene was supplied to the gas purification tower 203 at a higher position than the unreacted propylene, i.e., near the top, were advantageous in terms of separation performance and showed a sharp decrease in energy consumption. On the other hand, Examples 3 and 4 had high energy consumption because the raw material propylene was supplied to a lower position than the unreacted propylene, i.e., the supply positions of the raw material propylene and unreacted propylene in the gas purification tower were not appropriate.

[0086] In Comparative Example 1, energy consumption was low because the raw material propylene was introduced into the reaction section 100 without purification. However, the concentration of impurities in the propylene recovered in the gas purification column 203 and in the final IPA product was high due to impurities contained in the raw material propylene. Therefore, it is difficult to use it as a high-purity IPA product.

[0087] Comparative Example 2 reduces the concentration of impurities in the propylene recovered by the gas purification tower and in the final IPA product by purifying the raw material propylene in a separate raw material purification unit 10 before introducing it into the reaction unit 100. However, this method has the disadvantage of increasing installation and operating costs compared to the example where the raw material propylene and unreacted propylene were simultaneously purified in the gas purification tower 203, as the number of columns required for the raw material purification unit 10 and the gas purification tower 203 increased to three. Furthermore, it was also less efficient in terms of energy consumption compared to Examples 1 and 2, where the supply location of the raw material propylene and unreacted propylene was optimized. [Explanation of symbols]

[0088] 10 Raw material refining department 100 reaction section 200 Gas Purification Section 201 Absorption Tower 202 Flash Drum / Gas Separation Tower 203 Gas purification tower 300 IPA purification department 301 Organic matter removal tower 302 Water removal tower 303 IPA Recovery Tower 304 Solvent recovery tower 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 reaction product to a gas purification unit to separate the gas component containing unreacted propylene, (S3) The step of supplying the reaction product from which the gas component has been separated to an IPA purification unit to obtain purified isopropyl alcohol, A method for producing isopropyl alcohol, comprising further supplying raw material propylene to the gas purification section to purify the raw material propylene and unreacted propylene.

2. The gas purification section includes an absorption tower, a flash drum, a gas separation tower, and a gas purification tower. The reaction product supplied to the lower part of the absorption tower is brought into contact with the process circulating water supplied to the upper part, thereby discharging the upper stream of the gas phase containing unreacted propylene and the lower stream of the liquid phase containing components absorbed by the process circulating water. The lower discharge stream of the absorption column is supplied to the flash drum and gas separation tower, and the upper stream of the gas phase containing the remaining unreacted propylene and the lower stream of the liquid phase containing isopropyl alcohol are discharged. The gas phase stream containing unreacted propylene discharged from the flash drum and gas separation tower, along with raw material propylene, is supplied to the gas purification tower, and the side stream of purified propylene and the lower stream of high-boiling-point components are discharged while the gas of low-boiling-point components is exhausted to the upper stage. A method for producing isopropyl alcohol according to claim 1, wherein purified propylene separated in the gas purification column is supplied to the reaction section.

3. The method for producing isopropyl alcohol according to claim 2, wherein the raw material propylene is supplied to a position higher than the unreacted propylene in the gas purification tower.

4. The supply port for the raw material propylene is supplied in stages ranging from 25% to 60% of the height from the top stage of the gas purification tower. The method for producing isopropyl alcohol according to claim 2, wherein the stream containing the unreacted propylene is supplied from the top of the gas purification column in stages with a height of 50% to 85%.

5. The method for producing isopropyl alcohol according to claim 2, 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, more specifically, 0.4:1 to 1.5:

1.

6. The aforementioned gas purification column operates at a temperature of 40 to 100°C and a flow rate of 10 to 30 kg / cm³. ２ A method for producing isopropyl alcohol according to claim 2, which is operated at a pressure of g.

7. The method for producing isopropyl alcohol according to claim 2, wherein the raw material propylene supplied to the gas purification tower contains 95 to 99.8% by weight of propylene relative to its total weight.

8. The method for producing isopropyl alcohol according to claim 2, wherein the raw material propylene and unreacted propylene purified in the gas purification column contain 97 to 99.8% by weight of propylene relative to their total weight.

9. The method for producing isopropyl alcohol according to claim 2, wherein the low-boiling point gas exhausted from the gas purification tower includes ethane, ethylene, and mixtures thereof.

10. The IPA purification section 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 phase stream discharged from the flash drum and gas separation tower of the gas purification section is supplied to the organic matter removal tower, brought into contact with process circulating water, and the upper stream containing organic matter and the lower stream containing isopropyl alcohol are discharged. The lower 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 lower stream containing water, and a side stream containing n-propyl alcohol (NPA). The upper discharge stream and organic solvent of the water removal tower are supplied to the IPA recovery tower, and the upper stream containing water and organic solvent and the lower stream containing IPA are discharged. The upper discharge stream of the IPA recovery tower is supplied from the solvent recovery tower to discharge the upper stream of solvent and the lower stream of water. A method for producing isopropyl alcohol according to any one of claims 1 to 9, comprising supplying the side discharge stream of the water removal tower to the n-propyl alcohol removal tower and discharging the stream containing NPA to the bottom.

Images