KR20210025805A - Method for separating ternary mixture - Google Patents

Abstract

The present invention relates to a method for separating a ternary mixture, and particularly, to a method for separating each ingredient from a mixture containing acrylonitrile, toluene and isopropyl alcohol. The method includes the steps of: supplying the mixture stream to a first distillation column, recovering toluene from the lower discharge stream, and supplying a part of the upper discharge stream containing acrylonitrile and isopropyl alcohol to a second distillation column; separating the upper discharge stream of the first distillation column supplied to the second distillation column, recovering a part of isopropyl alcohol from the lower discharge stream, and supplying a part of the upper discharge stream containing acrylonitrile and isopropyl alcohol to a third distillation column; and separating the upper discharge stream of the second distillation column supplied to the third distillation column, recovering a part of acrylonitrile from the lower discharge stream, and supplying a part of the upper discharge stream containing acrylonitrile and isopropyl alcohol to the second distillation column, wherein the second distillation column is operated under a lower pressure, and the third distillation column is operated under a high pressure.

Description

Separation method of ternary mixture{METHOD FOR SEPARATING TERNARY MIXTURE}

The present invention relates to a method for separating a ternary mixture, and more particularly, to a method for separating each component from a ternary mixture comprising acrylonitrile, toluene and isopropyl alcohol.

The dimerization reaction of acrylonitrile (AN) is, in the presence of a catalyst, acrylonitrile monomer is mixed with a proton donating solvent such as isopropyl alcohol (IPA) and toluene. It is a process of dimerization by reacting in a solvent containing an inert solvent such as TOL).

Conventionally, research has been focused on a method of separating and reusing a catalyst from by-products including acrylonitrile, an unreacted monomer, isopropyl alcohol, toluene, and a catalyst after the reaction in the acrylonitrile dimerization reaction. However, in order to construct a commercial process, a method for recovering the unreacted acrylonitrile monomer and the solvent is required.

In order to reuse the unreacted acrylonitrile monomer, isopropyl alcohol and toluene from the acrylonitrile dimerization reaction by-product, each component must be separated for impurity management. Since an azeotropic point exists between toluene, high purity separation is difficult with a general distillation method.

Therefore, it is necessary to study a method of separating each component of acrylonitrile monomer, isopropyl alcohol, and toluene from acrylonitrile dimerization reaction by-products with high purity.

US 4958042 B

The problem to be solved in the present invention is to provide a method for separating a ternary mixture for separating each component of acrylonitrile, toluene, and isopropyl alcohol with high purity in order to solve the problems mentioned in the technology behind the background of the invention. It is to do.

That is, the present invention uses a plurality of distillation columns, and by adjusting the pressure conditions of each of the distillation columns, each component of acrylonitrile, toluene and isopropyl alcohol is highly purified from by-products discharged from the acrylonitrile dimerization reaction. It is an object of the present invention to provide a method for separating a ternary mixture that can be separated into and reused by facilitating impurity management, thereby significantly reducing process costs and improving economic efficiency.

According to an embodiment of the present invention for solving the above problems, the present invention is a method of separating each component from a mixture containing acrylonitrile, toluene, and isopropyl alcohol, wherein the mixture stream is divided into a first distillation column. And recovering toluene from the bottom effluent stream by feeding to a second distillation column, and supplying a partial stream of the top effluent stream comprising acrylonitrile and isopropyl alcohol to a second distillation column; Separating the upper discharge stream of the first distillation column supplied to the second distillation column to partially recover isopropyl alcohol from the lower discharge stream, and a third distillation of a partial stream of the upper discharge stream containing acrylonitrile and isopropyl alcohol. Supplying to the column; And separating the upper discharge stream of the second distillation column supplied to the third distillation column to partially recover acrylonitrile from the lower discharge stream, and to produce a partial stream of the upper discharge stream including acrylonitrile and isopropyl alcohol. It includes the step of supplying the 2 distillation column, wherein the second distillation column is operated at a low pressure, and the third distillation column is operated at a high pressure, it is possible to provide a separation method of a ternary mixture.

According to the separation method of the ternary mixture of the present invention, a mixture stream containing acrylonitrile, toluene, and isopropyl alcohol is supplied to a first distillation column to separate toluene first, and acrylonitrile and isopropyl from which toluene is separated. Separating the isopropyl alcohol from the second distillation column while circulating the stream containing alcohol to the second distillation column having a low pressure and a third distillation column having a high pressure, and separating the acrylonitrile from the third distillation column, the acrylonitrile , Toluene and isopropyl alcohol can be separated in high purity and reused in the process, thereby facilitating impurity management and significantly reducing process costs, thereby securing economical efficiency.

1 is a flowchart of a method for separating a ternary mixture according to an embodiment of the present invention.

The terms or words used in the description and claims of the present invention should not be construed as being limited to a conventional or dictionary meaning, and the inventors appropriately explain the concept of terms in order to explain their own invention in the best way. Based on the principle that it can be defined, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term'stream' may mean the flow of fluid in the process, and may also mean the fluid itself flowing in the pipe. Specifically, the'stream' may mean both the fluid itself and the flow of the fluid flowing in a pipe connecting each device. In addition, the fluid may mean gas or liquid.

In the present invention, the'acrylonitrile monomer' may be described as'acrylonitrile' for convenience.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1 to aid in understanding the present invention.

According to the present invention, a method for separating a ternary mixture is provided. As a method of separating the ternary mixture, a method of separating each component from a mixture containing acrylonitrile, toluene and isopropyl alcohol, wherein the mixture stream is supplied to a first distillation column 310 and Recovering toluene and feeding a partial stream of the overheads stream comprising acrylonitrile and isopropyl alcohol to the second distillation column (320); The upper discharge stream of the first distillation column 310 supplied to the second distillation column 320 is separated to partially recover isopropyl alcohol from the lower discharge stream, and the upper discharge stream containing acrylonitrile and isopropyl alcohol Supplying some streams to the third distillation column 330; And separating the upper discharge stream of the second distillation column 320 supplied to the third distillation column 330 to partially recover acrylonitrile from the lower discharge stream, and to discharge the upper discharge including acrylonitrile and isopropyl alcohol. Including the step of supplying some streams of the stream to the second distillation column 320, the second distillation column 320 is operated at low pressure, the third distillation column 330 is operated at high pressure. It is possible to provide a method for separating a branched mixture.

According to an embodiment of the present invention, the mixture containing acrylonitrile, toluene, and isopropyl alcohol may be a by-product generated from a dimerization reaction of acrylonitrile. Specifically, the dimerization reaction of acrylonitrile may be a process of dimerization by reacting acrylonitrile in a solvent including a proton donor solvent such as isopropyl alcohol and an inert solvent such as toluene in the presence of a catalyst.

Conventionally, research has been focused on a method of separating and reusing a catalyst from by-products including unreacted acrylonitrile and solvents such as isopropyl alcohol, toluene, and catalyst after the reaction in the acrylonitrile dimerization reaction. Studies for separating and reusing ronitrile, isopropyl alcohol and toluene have not been sufficiently conducted due to the azeophilic point between acrylonitrile and isopropyl alcohol and acrylonitrile and toluene, which makes high-purity separation difficult. On the other hand, the present invention is to provide a method for separating acrylonitrile, toluene, and isopropyl alcohol with high purity from by-products generated from the acrylonitrile dimerization reaction.

The acrylonitrile dimerization reaction includes: supplying acrylonitrile, toluene and isopropyl alcohol to a dimerization reactor 100 to dimerize acrylonitrile; Filtering the stream discharged from the dimerization reactor 100 to remove solids; And supplying the filtrate separated through the filtration to a preliminary distillation column 300 to recover by-products including acrylonitrile, toluene, and isopropyl alcohol as an upper discharge stream, wherein the acrylonitrile and toluene And the upper discharge stream of the preliminary distillation column 300 including by-products including isopropyl alcohol may be supplied to the first distillation column 310.

The step of dimerizing acrylonitrile by supplying acrylonitrile, toluene and isopropyl alcohol to the dimerization reactor 100 is a dimerization reactor 100 of acrylonitrile, toluene and isopropyl alcohol in the presence of hydrogen. And can be carried out at a temperature of 20° C. to 250° C., 50° C. to 250° C., or 70° C. to 220° C. By dimerizing the acrylonitrile, a straight-chain acrylonitrile dimer including adiponitrile, 1,4-dicyanobutene, and 1,4-dicyanobutadiene can be prepared.

In the step of dimerizing the acrylonitrile, a catalyst may be further included. The catalyst may include at least one selected from the group consisting of phosphinite and phosphonite. For example, the catalyst may be represented by the following formula (1).

[Formula 1]

In Formula 1,

R represents a C 1 to C 5 alkyl group or a C 1 to C 8 cycloalkyl group,

R ₁ to R ₃ each represent hydrogen, an alkyl group having 1 to 5 carbon atoms, an amino group or an alkoxy group,

n is an integer of 1 to 3, and m is an integer of 1 to 3.

For example, in Formula 1, R may be a methyl group, an ethyl group, an isopropyl group, or a cyclohexyl group.

After the step of dimerizing the acrylonitrile, the stream discharged from the dimerization reactor 100 undergoes a filtering step using a filter 200. The exhaust stream of the dimerization reactor 100 from which solids are removed during the filtering step is supplied to the preliminary distillation column 300. In the preliminary distillation column 300, a stream containing acrylonitrile, toluene, and isopropyl alcohol is discharged as an upper discharge stream, and a stream including an acrylonitrile dimer and a catalyst is discharged as a lower discharge stream. The stream including the acrylonitrile dimer and catalyst discharged to the lower discharge stream of the preliminary distillation column 300 may be separated into respective components through a separate separation step.

According to an embodiment of the present invention, the stream containing acrylonitrile, toluene, and isopropyl alcohol discharged from the upper discharge stream of the preliminary distillation column 300 is supplied to the first distillation column 310 from the lower discharge stream. The toluene can be recovered and a partial stream of the overhead effluent stream comprising acrylonitrile and isopropyl alcohol can be fed to the second distillation column 320.

The operating pressure of the first distillation column 310 may be performed at a higher pressure than normal pressure. The operating pressure of the first distillation column 310 may be 1.2 bar to 2.2 bar. For example, the operating pressure of the first distillation column 310 may be 1.3 bar to 2.2 bar, 1.5 bar to 2.2 bar, or 1.9 bar to 2.1 bar. It is difficult to separate toluene with high purity due to the distillation zone formed of acrylonitrile and isopropyl alcohol, and acrylonitrile and toluene by controlling the azeotropic point composition by controlling the operating pressure of the first distillation column 310 within the above range. You can solve the problem.

The flow rate of toluene in the lower discharge stream of the first distillation column 310 may be 0.95 or more compared to the flow rate of the lower discharge stream of the first distillation column 310. For example, the flow rate of toluene in the lower discharge stream of the first distillation column 310 relative to the flow rate of the lower discharge stream of the first distillation column 310 may be 0.95 to 1, 0.97 to 1, or 0.98 to 1. As described above, since the lower discharge stream of the first distillation column 310 contains toluene at a level of nearly 100% purity, toluene used in the acrylonitrile dimerization reaction can be recovered with high purity.

The upper discharge stream of the first distillation column 310 is supplied to a first condenser (not shown), and some streams of the first condenser (not shown) discharge stream are refluxed to the first distillation column 310, and the rest The stream may be supplied to the second distillation column 320. In this case, the reflux ratio of the first distillation column 310 may be 1.5 to 10. For example, the reflux ratio of the first distillation column 310 may be 1.5 to 9, 2.5 to 5, or 2.5 to 3.5. By controlling the reflux ratio of the first distillation column 310 to the above range, it is easy to separate the lower discharge stream containing toluene and the upper discharge stream containing acrylonitrile and isopropyl alcohol, and toluene is removed from the lower discharge stream. It can be recovered with high purity.

According to an embodiment of the present invention, high purity toluene is recovered from the upper discharge stream in the first distillation column 310, and a stream containing acrylonitrile and isopropyl alcohol is supplied to the second distillation column 320. I can.

The stream containing acrylonitrile and isopropyl alcohol discharged to the upper discharge stream of the first distillation column 310 is supplied to the second distillation column 320 to recover isopropyl alcohol from the lower discharge stream, and acrylonitrile And a partial stream of the upper discharge stream including isopropyl alcohol may be supplied to the third distillation column 330.

The operating pressure of the second distillation column 320 may be 0.3 bar to 1.1 bar. For example, the operating pressure of the second distillation column 320 may be 0.4 bar to 1.1.1 bar, 0.6 bar to 1.05 bar, or 0.9 bar to 1.05 bar. By controlling the operating pressure of the second distillation column 320 within the above range, isopropyl alcohol can be recovered with high purity as a lower discharge stream.

The flow rate of the isopropyl alcohol in the lower discharge stream of the second distillation column 320 compared to the flow rate of the lower discharge stream of the second distillation column 320 may be 0.95 or more. For example, the flow rate of isopropyl alcohol in the lower discharge stream of the second distillation column 320 relative to the flow rate of the lower discharge stream of the second distillation column 320 may be 0.95 to 1, 0.97 to 1, or 0.98 to 1. . As described above, the lower discharge stream of the second distillation column 320 contains isopropyl alcohol at a level of nearly 100% purity, so that the isopropyl alcohol used in the acrylonitrile dimerization reaction can be recovered with high purity. .

The upper discharge stream of the second distillation column 320 is supplied to a second condenser (not shown), and some streams of the second condenser (not shown) discharge stream are refluxed to the second distillation column 320, and the rest The stream may be supplied to the third distillation column 330. In this case, the reflux ratio of the second distillation column 320 may be 1.5 to 5. For example, the reflux ratio of the second distillation column 320 may be 1.5 to 4, 1.5 to 3, or 1.8 to 2.4. By controlling the reflux ratio of the second distillation column 320 to the above range, isopropyl alcohol can be recovered with high purity from the lower discharge stream.

According to an embodiment of the present invention, the upper discharge stream of the second distillation column 320 supplied to the third distillation column 330 is separated to partially recover acrylonitrile from the lower discharge stream, and acrylonitrile and A partial stream of the overhead discharge stream containing isopropyl alcohol may be supplied to the second distillation column 320.

The operating pressure of the third distillation column 330 may be 1 bar to 9 bar. For example, the operating pressure of the third distillation column 330 may be 3 bar to 9 bar, 5 bar to 8 bar, or 5.5 bar to 7.5 bar. By controlling the operating pressure of the third distillation column 330 within the above range, acrylonitrile can be recovered with high purity as a lower discharge stream.

The upper discharge stream of the third distillation column 330 is supplied to a third condenser (not shown), and some streams of the third condenser (not shown) discharge stream are refluxed to the third distillation column 330, and the rest The stream may be supplied to the second distillation column 320. In this case, the reflux ratio of the third distillation column 330 may be 1.5 to 5. For example, the reflux ratio of the third distillation column 330 may be 1.5 to 4, 1.5 to 3, or 1.8 to 2.4. By controlling the reflux ratio of the third distillation column 330 to the above range, acrylonitrile can be recovered with high purity from the lower discharge stream.

The upper portion of the third distillation column 330 supplied to the second distillation column 320 compared to the flow rate of acrylonitrile and isopropyl alcohol in the upper discharge stream of the second distillation column 320 supplied to the third distillation column 330 The flow rate of the discharge stream can be between 0.8 and 1.2. For example, the third distillation column supplied to the second distillation column 320 compared to the flow rate of acrylonitrile and isopropyl alcohol in the upper discharge stream of the second distillation column 320 supplied to the third distillation column 330 ( 330) The flow rate of the upper discharge stream may be 0.83 to 1.15, 0.85 to 1.1, or 0.95 to 1.05. In this way, by increasing the flow rate for recycling from the third distillation column 330 to the second distillation column 320, the isopropyl alcohol is separated from the lower discharge stream of the second distillation column 320 with high purity and at the same time, the third distillation Acrylonitrile can be separated from the bottom effluent stream of column 330 with high purity.

According to an embodiment of the present invention, the upper discharge stream of the third distillation column 330 may be recycled to the first distillation column 310. When the upper discharge stream of the third distillation column 330 is recycled to the first distillation column 310, toluene can be recovered from the first distillation column 310 with high purity by adjusting the composition in the first distillation column 310. have.

According to an embodiment of the present invention, the upper discharge stream of the third distillation column 330 may be recycled to the preliminary distillation column 300. When the upper discharge stream of the third distillation column 330 is recycled to the preliminary distillation column 300, the composition in the preliminary distillation column 300 is adjusted to provide an upper discharge stream containing acrylonitrile, isopropyl alcohol, and toluene and acrylonitrile. It is possible to more easily separate the bottoms effluent stream comprising nitrile dimers and catalysts and the like.

The flow rate of acrylonitrile in the lower discharge stream of the third distillation column 330 may be 0.95 or more compared to the flow rate of the lower discharge stream of the third distillation column 330. For example, the flow rate of acrylonitrile in the lower discharge stream of the third distillation column 330 compared to the flow rate of the lower discharge stream of the third distillation column 330 may be 0.95 to 1, 0.97 to 1, or 0.98 to 1. . As described above, since the lower discharge stream of the third distillation column 330 contains acrylonitrile at a level of nearly 100% purity, unreacted acrylonitrile in the acrylonitrile dimerization reaction can be recovered with high purity. have.

According to an embodiment of the present invention, the second distillation column 320 and the third distillation column 330 circulate a stream containing acrylonitrile and isopropyl alcohol, and pressurize acrylonitrile and isopropyl alcohol. It can be separated and recovered in high purity by pressure swing distillation. Specifically, while circulating a stream containing acrylonitrile and isopropyl alcohol, isopropyl alcohol is separated from the lower discharge stream of the low pressure second distillation column 320, and the lower portion of the high pressure third distillation column 330 Acrylonitrile can be separated from the effluent stream. Since the azeotrope composition of the acrylonitrile and isopropyl alcohol easily changes depending on the pressure, each component by changing the pressure while circulating the low pressure second distillation column 320 and the high pressure third distillation column 330 Can be separated with high purity.

According to an embodiment of the present invention, the distillation column separating the acrylonitrile and isopropyl alcohol may be changed depending on the case. For example, acrylonitrile may be separated from the lower discharge stream of the second distillation column 320 and isopropyl alcohol may be separated from the lower discharge stream of the third distillation column 330.

According to an embodiment of the present invention, the lower discharge stream of the third distillation column 330 including the acrylonitrile is supplied to a fourth distillation column (not shown), and acrylonitrile can be recovered as the lower discharge stream. have. In this way, by supplying the lower discharge stream of the third distillation column 330 containing high purity acrylonitrile to the fourth distillation column (not shown) to additionally remove impurities with a low boiling point, more highly purified acrylonitrile is recovered. can do.

According to an embodiment of the present invention, the lower discharge stream of the second distillation column 320 containing the isopropyl alcohol is supplied to the fifth distillation column (not shown), and isopropyl alcohol can be recovered as the lower discharge stream. have. In this way, by supplying the lower discharge stream of the second distillation column 320 containing high purity isopropyl alcohol to the fifth distillation column (not shown) to additionally remove impurities having a low boiling point, higher purity isopropyl alcohol can be obtained. Can be recovered.

The fourth distillation column (not shown) and the fifth distillation column (not shown) are not particularly limited as long as they are devices used for separating a specific component from a mixture through distillation, and, for example, may include a flash distillation drum. have.

Acrylonitrile, toluene, and isopropyl alcohol recovered from the separation method of the ternary mixture may be supplied to the dimerization reactor 100 and reused in the dimerization reaction of acrylonitrile. For example, toluene separated from the lower discharge stream of the first distillation column 310, isopropyl alcohol separated from the lower discharge stream of the second distillation column 320, and acrylic separated from the lower discharge stream of the third distillation column 330 The ronitrile may be re-supplied to the dimerization reactor 100 and be reused by participating in the dimerization reaction of acrylonitrile.

According to an embodiment of the present invention, in a method of separating a ternary mixture, if necessary, a distillation column (not shown), a condenser (not shown), a reboiler (not shown), a pump (not shown), a compressor (not shown) And a mixer (not shown) may be additionally installed.

As described above, the method for separating the ternary mixture according to the present invention has been shown in the description and drawings, but the description and drawings in the above description and show only the essential components for understanding the present invention, and are shown in the description and drawings. In addition to one process and apparatus, processes and apparatuses not separately described and not shown may be appropriately applied and used to carry out the separation method of the ternary mixture according to the present invention.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are intended to illustrate the present invention, and that various changes and modifications can be made within the scope of the present invention and the scope of the technical idea are obvious to those skilled in the art, and the scope of the present invention is not limited thereto.

Example

1, 9,500 kg/hr of acrylonitrile as a monomer, 3,220 kg/hr of isopropyl alcohol and 29,140 kg/hr of toluene as a solvent were supplied to the dimerization reactor 100, and phosphine as a catalyst. Acrylonitrile dimerization reaction was carried out using a knight.

The discharge stream of the dimerization reactor 100 after the reaction is completed is supplied to the filter 200 to remove solids, and the filtrate from which the solids have been removed is supplied to the preliminary distillation column 300 to obtain acrylonitrile and isopropyl alcohol as upper discharge streams. And toluene were separated, and acrylonitrile dimer and catalyst were separated as a bottom effluent stream.

The upper discharge stream of the preliminary distillation column 300 containing the acrylonitrile, isopropyl alcohol, and toluene is supplied to the first distillation column 310, and toluene is separated from the lower discharge stream and supplied to the dimerization reactor 100. In addition, some streams of the upper discharge stream were refluxed and the remaining streams were fed to the second distillation column (320).

Then, in the second distillation column 320, isopropyl alcohol was separated from the lower discharge stream and supplied to the dimerization reactor 100, and some streams of the upper discharge stream were refluxed and the remaining streams were converted into the third distillation column 330. ).

Then, in the third distillation column 330, acrylonitrile was separated from the lower discharge stream and supplied to the dimerization reactor 100, and some streams of the upper discharge stream were refluxed and the remaining streams were transferred to the second distillation column 320. ).

At this time, the operating pressure of the first distillation column 310, the second distillation column 320, and the third distillation column 330, the reflux ratio, and the supply from the second distillation column 320 to the third distillation column 330 The flow rate (circulation amount) of the stream circulating from the third distillation column 330 to the second distillation column 320 compared to the flow rate of acrylonitrile and isopropyl alcohol (AN+IPA) in the resulting stream and discharge to the bottom of each distillation column The purity of toluene, isopropyl alcohol, and acrylonitrile recovered from the stream is shown in Table 1 below.

First distillation column Second distillation column 3rd distillation column Operating pressure (bar) 2 One 6.3 Reflux 2.7 2.2 2.2 Circulation N.A. N.A. 0.9 water 99% toluene 99% isopropyl alcohol 99% acrylonitrile

Referring to Table 1, the operating pressure of the first distillation column 310 is controlled to 2 bar and the reflux ratio is controlled to 2.7, the operating pressure of the second distillation column 320 is controlled to 1 bar and the reflux ratio is controlled to 2.2, 3 By controlling the operating pressure of the distillation column 330 to 6.3 bar and the reflux ratio to 2.2, 99% or more of toluene is recovered from the lower discharge stream of the first distillation column 310, and from the lower discharge stream of the second distillation column 320. At least 99% of isopropyl alcohol was recovered, and at least 99% of acrylonitrile could be recovered from the bottom effluent stream of the third distillation column 330 and reused in the acrylonitrile dimerization reaction. Conventional dimerization of acrylonitrile Although the method of separating unreacted monomers or solvents among the by-products generated from the reaction has not been studied, acrylonitrile, isopropyl alcohol, and toluene are separated in high purity by the separation method according to the present invention and reused in the dimerization reaction, The economic efficiency can be improved by remarkably reducing the process cost.

Comparative example

Comparative Example 1

In the step of performing the acrylonitrile dimerization reaction in the same manner as in the above embodiment, but separating each component of acrylonitrile, isopropyl alcohol, and toluene discharged from the dimerization reaction, the first distillation column 310, Operating pressure and reflux ratio of the second distillation column 320 and the third distillation column 330, and flow rates of acrylonitrile and isopropyl alcohol in the stream supplied from the second distillation column 320 to the third distillation column 330 In contrast, the flow rate (circulation amount) of the stream circulated from the third distillation column 330 to the second distillation column 320 was controlled as shown in Table 2 below.

First distillation column Second distillation column 3rd distillation column Operating pressure (bar) 2 3 One Reflux 2.7 2.2 2.2 Circulation N.A. N.A. One water 99% toluene 90% acrylonitrile 80% isopropyl alcohol

Referring to Table 2, the operating pressure of the first distillation column 310 is controlled to 2 bar and the reflux ratio is controlled to 2.7, the operating pressure of the second distillation column 320 is controlled to 3 bar and the reflux ratio is controlled to 2.2, 3 When the operating pressure of the distillation column 330 is controlled to 1 bar and the reflux ratio is controlled to 2.2, the purity of the acrylonitrile recovered from the lower discharge stream of the second distillation column 320 is 90%, and the third distillation column 330 ) It was found that the purity of the isopropyl alcohol recovered from the lower discharge stream was 80%, which was low compared to the Example. In this case, the operating pressure of the second distillation column 320 was 3 bar, and the third distillation column As a result of not breaking the azeotrope composition between acrylonitrile and isopropyl alcohol because the operating pressure of 330 was not properly adjusted to the operating pressure of the second distillation column 320 and the third distillation column 330 at 1 bar. As, it can be seen that acrylonitrile and isopropyl alcohol were obtained with low purity.

Comparative Example 2

In the step of performing the acrylonitrile dimerization reaction in the same manner as in the above embodiment, but separating each component of acrylonitrile, isopropyl alcohol, and toluene discharged from the dimerization reaction, the first distillation column 310, Operating pressure and reflux ratio of the second distillation column 320 and the third distillation column 330, and flow rates of acrylonitrile and isopropyl alcohol in the stream supplied from the second distillation column 320 to the third distillation column 330 In contrast, the flow rate (circulation amount) of the stream circulated from the third distillation column 330 to the second distillation column 320 was controlled as shown in Table 3 below.

First distillation column Second distillation column 3rd distillation column Operating pressure (bar) One One 6.3 Reflux 2.7 2.2 2.2 Circulation N.A. N.A. One water 83% toluene 99% isopropyl alcohol 99% acrylonitrile

Referring to Table 3, the operating pressure of the first distillation column 310 is controlled to 1 bar and the reflux ratio is controlled to 2.7, the operating pressure of the second distillation column 320 is controlled to 1 bar and the reflux ratio is controlled to 2, 3 When the operating pressure of the distillation column 330 is controlled to 6 bar and the reflux ratio is controlled to 2, the purity of toluene recovered from the lower discharge stream of the first distillation column 310 is 83%, which is low compared to the examples. In this case, as a result of operating the first distillation column at atmospheric pressure (1 bar), toluene was not obtained in high purity due to the azeotropic composition existing between acrylonitrile and isopropyl alcohol and acrylonitrile and toluene. Can be seen.

Comparative Example 3

In the step of performing the acrylonitrile dimerization reaction in the same manner as in the above embodiment, but separating each component of acrylonitrile, isopropyl alcohol, and toluene discharged from the dimerization reaction, the first distillation column 310, Operating pressure, reflux ratio of the second distillation column 320 and the third distillation column 330, and flow rates of acrylonitrile and isopropyl alcohol in the stream supplied from the second distillation column 320 to the third distillation column 330 In contrast, the flow rate (circulation amount) of the stream circulated from the third distillation column 330 to the second distillation column 320 was controlled as shown in Table 4 below.

First distillation column Second distillation column 3rd distillation column Operating pressure (bar) 2 One 6.3 Reflux 2.7 One 2.2 Circulation N.A. N.A. One water 99% toluene 97% isopropyl alcohol 97% acrylonitrile

Referring to Table 4, the operating pressure of the first distillation column 310 is controlled to 2 bar and the reflux ratio is controlled to 2.7, the operating pressure of the second distillation column 320 is controlled to 1 bar and the reflux ratio is controlled to 1, 3 When the operating pressure of the distillation column 330 is controlled to 6.3 bar and the reflux ratio is controlled to 2.2, the isopropyl alcohol and acrylonitrile recovered from the lower discharge streams of the second distillation column 320 and the third distillation column 330 are It was found that the purity was 97%, which was low compared to the examples. Through this, it can be seen that the reflux ratio of each distillation column affects the purity of components separated from each distillation column.

100: dimerization reactor 200: filter
300: preliminary distillation column 310: first distillation column
320: second distillation column 330: third distillation column

Claims (10)

A method of separating each component from a mixture comprising acrylonitrile, toluene and isopropyl alcohol, comprising:
Supplying the mixture stream to a first distillation column to recover toluene from a bottom effluent stream, and supplying a partial stream of the top effluent stream comprising acrylonitrile and isopropyl alcohol to a second distillation column;
Separating the upper discharge stream of the first distillation column supplied to the second distillation column to partially recover isopropyl alcohol from the lower discharge stream, and a third distillation of a partial stream of the upper discharge stream containing acrylonitrile and isopropyl alcohol. Supplying to the column; And
The upper discharge stream of the second distillation column supplied to the third distillation column is separated to partially recover acrylonitrile from the lower discharge stream, and a partial stream of the upper discharge stream containing acrylonitrile and isopropyl alcohol is second Including the step of supplying the distillation column,
The second distillation column is operated at low pressure, and the third distillation column is operated at high pressure. The method of claim 1,
The operating pressure of the second distillation column is 0.3 bar to 1.1 bar,
The method of separating a ternary mixture in which the operating pressure of the third distillation column is 1 bar to 9 bar. The method of claim 1,
The method of separating a ternary mixture in which the operating pressure of the first distillation column is 1.2 bar to 2.2 bar. The method of claim 1,
A method of separating a ternary mixture in which the flow rate of the upper discharge stream of the third distillation column supplied to the second distillation column is 0.8 to 1.2 compared to the flow rate of the discharge stream above the second distillation column supplied to the third distillation column. The method of claim 1,
The upper discharge stream of the first distillation column is supplied to the first condenser, some streams of the first condenser discharge stream are refluxed to the first distillation column, the remaining stream is supplied to the second distillation column, and the reflux ratio is 1.5 To 10,
The upper discharge stream of the second distillation column is supplied to a second condenser, some streams of the second condenser discharge stream are refluxed to a second distillation column, and the remaining stream is supplied to a third distillation column, and the reflux ratio is 1.5 To 5,
The upper discharge stream of the third distillation column is supplied to a third condenser, some streams of the third condenser discharge stream are refluxed to a third distillation column, and the remaining stream is supplied to a second distillation column, and the reflux ratio is 1.5 Separation method of the ternary mixture of 5 to. The method of claim 1,
The mixture containing acrylonitrile, toluene and isopropyl alcohol is a method for separating a ternary mixture, which is a by-product generated from a dimerization reaction of acrylonitrile. The method of claim 6,
The dimerization reaction of the acrylonitrile,
Supplying acrylonitrile, toluene, and isopropyl alcohol to a dimerization reactor to perform a dimerization reaction of acrylonitrile;
Filtering the stream discharged from the dimerization reactor to remove solids; And
Supplying the filtrate separated through the filtration to a preliminary distillation column to recover by-products including acrylonitrile, toluene and isopropyl alcohol as an upper discharge stream,
The method of separating a ternary mixture, wherein the preliminary distillation column upper discharge stream is supplied to the first distillation column. The method of claim 7,
The recovered acrylonitrile, toluene, and isopropyl alcohol are each reused in the dimerization reaction of acrylonitrile, a method for separating a ternary mixture. The method of claim 1,
The flow rate of toluene in the first distillation column lower discharge stream compared to the flow rate of the first distillation column lower discharge stream is 0.95 or more,
The flow rate of isopropyl alcohol in the second distillation column lower discharge stream relative to the flow rate of the second distillation column lower discharge stream is 0.95 or more,
A method for separating a ternary mixture in which the flow rate of acrylonitrile in the lower discharge stream of the third distillation column is 0.95 or higher compared to the flow rate of the lower discharge stream of the third distillation column. The method of claim 1,
The third distillation column bottom discharge stream containing the acrylonitrile is supplied to a fourth distillation column, and the method for separating a ternary mixture in which acrylonitrile is recovered as a bottom discharge stream from the fourth distillation column.

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