KR102723566B1 - Method for preparing acrylonitrile dimer - Google Patents

Abstract

The present invention relates to a method for producing an acrylonitrile dimer, and provides a method for producing an acrylonitrile dimer, comprising the steps of: (S10) supplying an acrylonitrile monomer, a phosphorus-based catalyst, an alcohol solvent, and an ionic liquid to a reactor to cause a dimerization reaction to produce a single-phase dimerization reaction product; (S20) supplying a reactor discharge stream containing the dimerization reaction product to a first distillation column, separating an alcohol solvent and unreacted acrylonitrile monomer from the top discharge stream, and supplying a bottom discharge stream containing the acrylonitrile dimer, an ionic liquid, and a phosphorus-based catalyst to a second distillation column; and (S30) separating an top discharge stream containing the acrylonitrile dimer in the second distillation column, and separating a bottom discharge stream containing the ionic liquid and the phosphorus-based catalyst.

Description

{METHOD FOR PREPARING ACRYLONITRILE DIMER}

The present invention relates to a method for producing an acrylonitrile dimer, and more specifically, to a method for producing a linear acrylonitrile dimer in high yield by effectively separating a phosphorus catalyst used as a catalyst in an acrylonitrile dimerization reaction.

Acrylonitrile dimer, especially linear acrylonitrile dimer, is used as an intermediate for the synthesis of hexamethylenediamine (HMDA), the main monomer of nylon 66, and is utilized in the manufacture of waterproofing agents, vulcanization accelerators, etc.

These acrylonitrile dimers can be obtained by a method of dimerizing an acrylonitrile monomer in the presence of a catalyst. Specifically, an acrylonitrile dimer can be produced by causing an acrylonitrile monomer to undergo a dimerization reaction using a ruthenium (Ru)-based compound, a cobalt (Co)-based compound, or a phosphorus (P)-based compound as a catalyst.

Among the above catalysts, a method for producing an acrylonitrile dimer using a ruthenium-based compound has been mainly studied, but there was a problem that the yield of the acrylonitrile dimer and the selectivity of the linear acrylonitrile dimer decreased due to the addition of hydrogen to cause the dimerization reaction. That is, as hydrogen was added, hydrogenation occurred along with the dimerization reaction of acrylonitrile, and a large amount of propionitrile as a byproduct was produced, which decreased the yield and selectivity.

Accordingly, a method of producing an acrylonitrile dimer using a phosphorus compound as a catalyst is attracting attention in order to increase the yield of the acrylonitrile dimer. As a method of producing an acrylonitrile dimer using the phosphorus compound as a catalyst, an example of which includes a method of introducing acrylonitrile into a mixed solvent containing an inert solvent such as an alcohol solvent and an aromatic hydrocarbon solvent as a proton donating solvent and causing a dimerization reaction in the presence of a phosphorus catalyst.

However, in the above method, there was a problem that separation between the phosphorus catalyst, acrylonitrile dimer, and mixed solvent was difficult due to the azeotropic problem of the alcohol solvent and the aromatic hydrocarbon solvent, resulting in a low recycling rate of the catalyst and a low yield of the acrylonitrile dimer.

In addition, the separation of the phosphorus catalyst, the acrylonitrile dimer, and the mixed solvent is performed by a distillation method. The distillation method is a method of separating the catalyst by applying heat by utilizing the characteristic of the phosphorus catalyst having a higher boiling point than the reaction product or products. When the catalyst is separated from the acrylonitrile dimerization reaction product by the distillation method, there is a problem in that the heat causes a side reaction of the acrylonitrile dimerization products to proceed, generating acrylonitrile trimers and multimers, thereby lowering the yield of the acrylonitrile dimer.

Therefore, a technology is required to increase the yield of acrylonitrile dimer while simultaneously increasing the recycling rate of the phosphorus catalyst.

US 4958042 A

The problem to be solved in the present invention is to provide a method for easily separating a phosphorus catalyst from an acrylonitrile dimerization reaction product and producing an acrylonitrile dimer in high yield in order to solve the problems mentioned in the background technology of the above invention.

That is, the present invention can solve the problem of difficulty in recovering a phosphorus catalyst when producing an acrylonitrile dimer using a conventional phosphorus catalyst, thereby reducing the yield of the acrylonitrile dimer, by using an ionic liquid as a reaction solvent when producing an acrylonitrile dimer.

According to one embodiment of the present invention for solving the above problems, the present invention can provide a method for producing an acrylonitrile dimer, comprising the steps of: (S10) supplying an acrylonitrile monomer, a phosphorus-based catalyst, an alcohol solvent, and an ionic liquid to a reactor to perform a dimerization reaction to produce a single-phase dimerization reaction product; (S20) supplying a reactor discharge stream including the dimerization reaction product to a first distillation column, separating an alcohol solvent and unreacted acrylonitrile monomer from the top discharge stream, and supplying a bottom discharge stream including the acrylonitrile dimer, the ionic liquid, and the phosphorus-based catalyst to a second distillation column; and (S30) separating an top discharge stream including the acrylonitrile dimer in the second distillation column, and separating a bottom discharge stream including the ionic liquid and the phosphorus-based catalyst.

According to the method for producing an acrylonitrile dimer of the present invention, when producing an acrylonitrile dimer, by using an ionic liquid as a reaction solvent instead of using a conventional aromatic hydrocarbon solvent, the acrylonitrile dimer can be separated with high purity, and there is an effect of facilitating the separation of a phosphorus catalyst.

In addition, the present invention enables the ionic liquid, product, and catalyst to exist at the bottom of the second distillation column at a temperature higher than the acrylonitrile dimerization reaction temperature due to the low vapor pressure characteristic of the ionic liquid when producing an acrylonitrile dimer, thereby effectively suppressing further reaction of the product and minimizing loss of the product and catalyst by allowing the product and catalyst to exist at a low concentration.

Figure 1 is a process flow diagram of a method for producing an acrylonitrile dimer according to one embodiment of the present invention.

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 in order to explain his or her own invention in the best possible manner.

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

Hereinafter, in order to help understand the present invention, the present invention will be described in more detail with reference to Drawing 1 below.

According to the present invention, a method for producing an acrylonitrile dimer is provided.

The present invention relates to a method for producing an acrylonitrile dimer, the method comprising: a step (S10) of supplying an acrylonitrile monomer, a phosphorus-based catalyst, an alcohol solvent, and an ionic liquid to a reactor to cause a dimerization reaction to produce a single-phase dimerization reaction product; a step (S20) of supplying a reactor discharge stream containing the dimerization reaction product to a first distillation column, separating an alcohol solvent and unreacted acrylonitrile monomer from the top discharge stream, and supplying a bottom discharge stream containing the acrylonitrile dimer, the ionic liquid, and the phosphorus-based catalyst to a second distillation column; and a step (S30) of separating an top discharge stream containing the acrylonitrile dimer in the second distillation column, and separating a bottom discharge stream containing the ionic liquid and the phosphorus-based catalyst.

The term “product” in the present invention may mean a substance to be obtained by a dimerization reaction, i.e., an acrylonitrile dimer.

In the present invention, the term "reaction product" may mean both a product (acrylonitrile dimer) and an unreacted product generated by a dimerization reaction of a reaction mixture. For example, in the dimerization reaction of step S10, the reaction mixture may mean an acrylonitrile monomer, a phosphorus catalyst, an alcohol solvent, and an ionic liquid, the product may mean an acrylonitrile dimer, and the reaction product may include all of an acrylonitrile dimer (product), an unreacted acrylonitrile monomer, an alcohol solvent, an ionic liquid, and a phosphorus catalyst.

In the present invention, the term "single phase" may mean a state in which, unlike an emulsion or colloid in which phase separation occurs, such as sedimentation of suspended matter when allowed to stand for a long time or through centrifugation, no phase separation occurs even when the mixture is allowed to stand for a long time or through centrifugation, and in which the components and physicochemical properties are the same no matter which part of the mixture is extracted. That is, the "single phase dimerization reaction product" may mean a mixture in which the reaction products, an acrylonitrile dimer, an acrylonitrile monomer, a phosphorus catalyst, and an alcohol, are all dissolved in the ionic liquid, and in which the components and physicochemical properties are the same no matter which part of the mixture is extracted.

On the other hand, for example, if water is used instead of alcohol in the reaction mixture, the phosphorus catalyst may react with water and change into an inactive state, so it may be preferable to use alcohol.

The above acrylonitrile dimer, particularly the linear acrylonitrile dimer, is used as an intermediate for the synthesis of hexamethylenediamine (HMDA), a main monomer of nylon 66, or is utilized in the manufacture of waterproofing agents, vulcanization accelerators, etc.

Conventionally, acrylonitrile dimers were obtained by a method of dimerizing acrylonitrile monomers in the presence of a catalyst. Specifically, acrylonitrile dimers were produced by dimerizing acrylonitrile monomers using a ruthenium (Ru)-based compound, a cobalt (Co)-based compound, or a phosphorus (P)-based compound as a catalyst.

Among the catalysts used to manufacture the above acrylonitrile dimer, a phosphorus catalyst in particular has excellent reactivity and selectivity, and thus, an acrylonitrile dimer was manufactured by introducing acrylonitrile into a mixed solvent containing an inert solvent such as an alcohol solvent and an aromatic hydrocarbon solvent as a proton donating solvent and causing a dimerization reaction.

However, in the above method, due to the azeotropic problem between the alcohol solvent and the aromatic hydrocarbon solvent, and between the acrylonitrile monomer and the aromatic hydrocarbon solvent, when the alcohol solvent, the aromatic hydrocarbon solvent and the acrylonitrile monomer are recycled, impurities and low-boiling-point by-products in the recycled unreacted acrylonitrile monomer accumulate, making it difficult to maintain the reaction conditions. Therefore, in order to prevent the accumulation of the impurities and by-products, a process step for purging must be added, or there is a problem in that the acrylonitrile dimer yield decreases due to the accumulation of impurities and by-products.

In addition, the separation of the phosphorus catalyst, the acrylonitrile dimer, and the mixed solvent is performed by a distillation method. The distillation method is a method of separating the catalyst by applying heat by utilizing the characteristic of the phosphorus catalyst having a higher boiling point than the reaction product or products. When the catalyst is separated from the acrylonitrile dimerization reaction product by the distillation method, there is a problem in that the thermal decomposition and side reactions of the acrylonitrile dimer products progress due to the high temperature conditions, and the thermal decomposition products of the acrylonitrile dimer, trimers, and oligomers higher than polymers are generated, thereby lowering the yield of the acrylonitrile dimer.

In this regard, the present invention aims to provide a method for producing an acrylonitrile dimer by using an ionic liquid as a reaction solvent instead of a conventional aromatic hydrocarbon solvent, thereby improving process efficiency by not adding unnecessary process steps, increasing the yield of the acrylonitrile dimer, separating the acrylonitrile dimer with high purity, and improving the recyclability of the phosphorus catalyst.

According to one embodiment of the present invention, the step S10 may be a step of supplying an acrylonitrile monomer, a phosphorus catalyst, an alcohol solvent, and an ionic liquid to a reactor (100) to cause a dimerization reaction to produce an acrylonitrile dimer.

According to one embodiment of the present invention, the acrylonitrile dimerization reaction in the step S10 can be prepared by a conventional method known in the art. For example, an appropriate amount of raw material can be supplied to the reactor (100) to perform the acrylonitrile dimerization reaction at an optimal temperature range and pressure range.

For example, the acrylonitrile dimerization reaction can be performed in a temperature range of 0° C. to 100° C. and a pressure range of 1 bar to 10 bar. When the acrylonitrile dimerization reaction is performed in the above temperature and pressure ranges, an acrylonitrile dimer can be produced with excellent conversion.

According to one embodiment of the present invention, the phosphorus catalyst can be represented by the following chemical formula 1.

[Chemical Formula 1]

In the above chemical formula 1,

R represents an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a cycloalkyl group having 3 to 8 carbon atoms, 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 and m are each independently an integer of 1 to 2, and the sum of n and m is 3.

As a specific example, the above-mentioned transfer catalyst can be represented by the following chemical formula 1-1.

[Chemical Formula 1-1]

In the above chemical formula 1-1,

R is a methyl group, an ethyl group, an isopropyl group or a cyclohexyl group, and R ₂ is hydrogen, a methyl group or an ethyl group.

As a more specific example, the above-mentioned transfer catalyst can be represented by the following chemical formula 1-2.

[Chemical Formula 1-2]

According to one embodiment of the present invention, the alcohol solvent may include, for example, at least one selected from the group consisting of isopropyl alcohol, methyl alcohol, and cyclohexane alcohol. As a specific example, the alcohol solvent may be isopropyl alcohol.

According to one embodiment of the present invention, the ionic liquid contains cations and anions, and its physical and chemical properties can be easily controlled by changing the properties of these cations and anions, so it is widely used in various fields.

In the above ionic liquid, the cation may include at least one selected from the group consisting of a pyridinium-based cation, an imidazolium-based cation, a pyrrolidinium-based cation, an ammonium-based cation, and a phosphonium-based cation.

The above pyridinium cations include, for example, 1-butyl-2-methylpyridinium cation, 1-butyl-3-methylpyridinium cation, butylmethylpyridinium cation, 1-butyl-4-dimethylacetylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-ethyl-2-methylpyridinium cation, 1-ethyl-3-methylpyridinium cation, 1-ethyl-4-dimethylacetylpyridinium cation, 1-ethyl-4-methylpyridinium cation, 1-hexyl-4-dimethylacetylpyridinium cation, 1-hexyl-4-methylpyridinium cation, 1-octyl-3-methylpyridinium cation, 1-octyl-4-methylpyridinium cation, 1-propyl-3-methylpyridinium cation, It may include at least one selected from the group consisting of 1-propyl-4-methylpyridinium cation, butylpyridinium cation, ethylpyridinium cation, heptylpyridinium cation, hexylpyridinium cation, hydroxypropylpyridinium cation, octylpyridinium cation, pentylpyridinium cation, and propylpyridinium cation.

In addition, the above imidazolium cations include, for example, butylethylimidazolium cation, butylmethylimidazolium cation, butyldimethylimidazolium cation, decaethylimidazolium cation, decamethylimidazolium cation, diethylimidazolium cation, dimethylimidazolium cation, ethyl-2,4-dimethylimidazolium cation, ethyldimethylimidazolium cation, ethylimidazolium cation, ethylmethylimidazolium cation, ethylpropylimidazolium cation, ethoxyethylmethylimidazolium cation, ethoxydimethylimidazolium cation, hexadecylmethylimidazolium cation, heptylmethylimidazolium cation, hexylethylimidazolium cation, hexylmethylimidazolium cation, hexyldimethylimidazolium cation, It may include at least one selected from the group consisting of a methoxyethyl methyl imidazolium cation, a methoxypropyl methyl imidazolium cation, a methyl imidazolium cation, a dimethyl imidazolium cation, a methyl nonylimidazolium cation, a methyl nonylimidazolium cation, an octadecyl methyl imidazolium cation, a hydroxylethyl methyl imidazolium cation, a hydroxyloctyl methyl imidazolium cation, a hydroxylpropyl methyl imidazolium cation, an octyl methyl imidazolium cation, an octyldimethyl imidazolium cation, a phenylethyl methyl imidazolium cation, a phenyl methyl imidazolium cation, a phenyl dimethyl imidazolium cation, a pentyl methyl imidazolium cation, and a propyl methyl imidazolium cation.

In addition, the pyrrolidinium-based cation may include at least one selected from the group consisting of, for example, a butylmethylpyrrolidinium cation, a butylpyrrolidinium cation, a hexylmethylpyrrolidinium cation, a hexylpyrrolidinium cation, an octylmethylpyrrolidinium cation, an octylpyrrolidinium cation, and a propylmethylpyrrolidinium cation.

In addition, the ammonium-based cation may include at least one selected from the group consisting of, for example, a butylammonium cation, a tributylammonium cation, a tetrabutylammonium cation, a butylethyldimethylammonium cation, a butyltrimethylammonium cation, a N,N,N-trimethylethanolammonium cation, an ethylammonium cation, a diethylammonium cation, a tetraethylammonium cation, a tetraheptylammonium cation, a tetrahexylammonium cation, a methylammonium cation, a dimethylammonium cation, a tetramethylammonium cation, an ammonium cation, a butyldimethylethanolammonium cation, a dimethylethanolammonium cation, an ethanolammonium cation, an ethyldimethylethanolammonium cation, a tetrapentylammonium cation, and a tetrapropylammonium cation.

Additionally, the phosphonium cation may include at least one selected from the group consisting of, for example, a tetrabutylphosphonium cation and a tributyloctylphosphonium cation.

Specifically, in the ionic liquid, the cation may include a pyridinium-based cation, and more specifically, the pyridinium-based cation may be at least one selected from the group consisting of a 1-butyl-4-methylpyridinium cation and a 1-ethyl-3-methylpyridinium cation.

In the above ionic liquid, the anion may include at least one selected from the group consisting of a bis(trifluoromethanesulfonyl)amide anion, a hexafluorophosphate anion, a trifluoromethanesulfonate anion, a dicyanamide anion, a tetrafluoroborate anion, a thiocyanate anion, a nitrate anion, a sulfonate anion, an ethyl sulfate anion, and a trifluoroacetate anion. Specifically, in the anionic liquid, the anion may include a tetrafluoroborate anion or an ethyl sulfonate anion.

More specifically, the ionic liquid may include at least one selected from the group consisting of 1-butyl-4-methylpyridinium tetrafluoroborate and 1-ethyl-3-methylpyridinium ethyl sulfate.

The ionic liquid may have a vapor pressure measured at a temperature of 100° C. of 0.003 Pa or less. For example, the vapor pressure measured at a temperature of 100° C. may be from 0.0001 Pa to 0.003 Pa, from 0.0005 Pa to 0.003 Pa, or from 0.001 Pa to 0.003 Pa. In this way, by using an ionic liquid having a very low vapor pressure as a solvent in the acrylonitrile dimerization reaction, the loss of product and catalyst can be minimized.

Specifically, by using an ionic liquid having a very low vapor pressure as a solvent, the ionic liquid, product, and catalyst are present at the bottom of the second distillation column (300) even at a temperature higher than the acrylonitrile dimerization reaction temperature, so that the product and catalyst are present at a low concentration (dilute), effectively suppressing further reaction of the product, thereby minimizing loss of the product and catalyst.

Meanwhile, for example, in the case where an aromatic hydrocarbon solvent having a vapor pressure of 1000 Pa or more at a temperature of 100° C. is used instead of the ionic liquid, as the flow rate of the aromatic hydrocarbon solvent separated from the upper portion of the second distillation column (300) increases above the acrylonitrile dimerization reaction temperature, the product and catalyst are present at a high concentration in the lower portion of the second distillation column (300), and the loss of the catalyst may occur due to additional reaction of the product, and the yield of the product, the acrylonitrile dimer, may decrease.

Specifically, the above-mentioned catalyst may be an active catalyst, and may be converted to an inactive state by an additional reaction occurring at the bottom of the second distillation column (300), thereby causing a loss of the catalyst.

In the above step S10, the ionic liquid may be supplied to the reactor after undergoing a step of removing moisture. For example, the step of removing moisture from the ionic liquid may include a step of preparing a mixed solution by mixing the ionic liquid and a second solvent; a step of removing moisture by introducing a porous material into the mixed solution; and a step of separating the ionic liquid from the mixed solution.

The second solvent used in the step of removing moisture from the ionic liquid may be a substance that is compatible with the ionic liquid and has low boiling point and viscosity. Specifically, the second solvent used in the step of removing moisture from the ionic liquid may be appropriately selected depending on the type of the ionic liquid, and for example, the second solvent may include at least one selected from the group consisting of ethyl acetate, alkyl acetate, ketone, alcohol, and acetonitrile.

The above porous material may include at least one selected from the group consisting of molecular sieves and zeolites commonly used in the art. When such a porous material is added to a mixed solution and maintained for a certain period of time, the porous material absorbs moisture, thereby removing moisture.

The step of separating the ionic liquid from the mixed solution from which moisture has been removed using the above porous material can be performed by an evaporation method through heating. In this way, when the mixed solution is heated, the ionic liquid with low vapor pressure does not evaporate, and only the second solvent evaporates, so that the ionic liquid can be easily separated. The heating temperature is, for example, It can be 25 ℃ to 200 ℃, 25 ℃ to 150 ℃, or 25 ℃ to 100 ℃. In addition, when evaporating through the heating, the pressure can be 100 mbar or less, 0.01 mbar to 100 mbar, or 0.1 mbar to 50 mbar. By evaporating the second solvent through heating under the above temperature and reduced pressure conditions, the ionic liquid can be effectively separated.

The ionic liquid may have a moisture content of 50 ppm or less. For example, the moisture content contained in the ionic liquid may be from 1 ppm to 50 ppm, from 1 ppm to 30 ppm, or from 1 ppm to 15 ppm, so that the ionic liquid contains almost no moisture. By using the ionic liquid having a moisture content within the above range, oxidation of the catalyst can be prevented, thereby improving the conversion rate and selectivity in the acrylonitrile dimerization reaction.

According to one embodiment of the present invention, when producing an acrylonitrile dimer, the yield of the acrylonitrile dimer can be improved by using a mixed solvent including an alcohol solvent and an ionic liquid. Specifically, in the present invention, by using an ionic liquid instead of a conventional aromatic hydrocarbon solvent, the yield of the acrylonitrile dimer can be improved compared to the case where a mixed solvent of an aromatic hydrocarbon solvent and an alcohol solvent was used in the past. More specifically, in the past, when the content of the alcohol solvent in the mixed solvent was lowered, the reaction rate decreased and the production of by-products increased, thereby reducing the yield of the acrylonitrile dimer, and when the content of the alcohol solvent was increased, the reaction rate increased, but the production of by-products also increased, thereby reducing the yield of the acrylonitrile dimer. In response to this, the present invention solves the above-mentioned conventional problems by using a mixed solvent including an alcohol solvent and an ionic liquid.

The volume ratio of the alcohol solvent and the ionic liquid supplied to the above reactor (100) may be 1:5 to 20. For example, the volume ratio of the alcohol solvent and the ionic liquid may be 1:5 to 18, 1:5 to 15, or 1:8 to 13. By mixing the alcohol solvent and the ionic liquid in a volume ratio within the above range and using it as a reaction solvent during the acrylonitrile dimerization reaction, the production of by-products can be suppressed, thereby improving the yield of the acrylonitrile dimer. As a specific example, when the volume ratio of the alcohol solvent and the ionic liquid is 1:5 or more, the reactivity of the phosphorus catalyst can be prevented from increasing excessively, thereby preventing the production of oligomers, and when it is 1:20 or less, the reaction rate can be prevented from decreasing, thereby having the effect of improving productivity.

In the above step S10, an acrylonitrile dimerization reaction product may be generated through an acrylonitrile dimerization reaction. Specifically, the acrylonitrile dimerization reaction product may include an acrylonitrile dimer, an unreacted acrylonitrile monomer, an alcohol solvent, a phosphorus catalyst, and an ionic liquid.

According to one embodiment of the present invention, step S20 may be a step of supplying an acrylonitrile dimerization reaction product generated through an acrylonitrile dimerization reaction in step S10 to a first distillation column (200), separating an alcohol solvent and unreacted acrylonitrile monomer from an upper discharge stream, and supplying a bottom discharge stream including an acrylonitrile dimer, an ionic liquid, and a phosphorus catalyst to a second distillation column (300).

In the above step S20, the operating temperature of the first distillation column (200) may be 10° C. to 60° C., 10° C. to 50° C., or 15° C. to 40° C. In addition, the operating pressure of the first distillation column (200) in the above step S20 may be 1 mbar to 200 mbar, 1 mbar to 80 mbar, or 1 mbar to 40 mbar. In this way, by controlling the operating temperature and operating pressure of the first distillation column (200) in the step S20 within the above ranges, the phosphorus catalyst, the acrylonitrile dimer, and the ionic liquid may be selectively evaporated and separated from the upper portion of the first distillation column (200).

According to one embodiment of the present invention, the step S30 may be a step for separating an upper discharge stream including an acrylonitrile dimer and a bottom discharge stream including a phosphorus catalyst and an ionic liquid from the bottom discharge stream of the first distillation column (200) in the step S20.

Specifically, in the step S20, the bottom discharge stream of the first distillation column (200) is supplied to the second distillation column (300), and in the second distillation column (300), an acrylonitrile dimer is separated from the top discharge stream, and a mixture of a phosphorus catalyst and an ionic liquid can be separated as a bottom discharge stream.

In the above step S30, the operating temperature of the second distillation column (300) may be 100° C. to 200° C., 100° C. to 180° C., or 100° C. to 150° C. In addition, the operating pressure of the second distillation column (300) in the above step S30 may be 0.005 mbar to 80 mbar, 0.005 mbar to 25 mbar, or 0.01 mbar to 6 mbar. In this way, by controlling the operating temperature and operating pressure of the second distillation column (300) within the above ranges in the above step S30, the acrylonitrile dimer can be selectively evaporated and separated from the upper discharge stream of the second distillation column (300).

In the above step S30, the acrylonitrile dimer separated from the upper portion of the second distillation column (300) may include a linear acrylonitrile dimer including 1,4-dicyanobutene, which can be converted into adiponitrile. In addition, the selectivity of the linear acrylonitrile dimer among the acrylonitrile dimer separated from the upper discharge stream of the second distillation column (300) in the step S30 may be 90% or more. In addition, the phosphorus catalyst and ionic liquid that are not separated from the upper portion of the second distillation column (300) in the step S30 may be separated from the lower portion of the second distillation column (300).

According to one embodiment of the present invention, the content of the phosphorus catalyst separated in the step S30 relative to the content of the phosphorus catalyst supplied to the reactor (100) in the step S10 may be 0.5 to 0.95, 0.60 to 0.95, or 0.80 to 0.95. As such, in the method for producing an acrylonitrile dimer according to the present invention, by using an ionic liquid as a reaction solvent, additional reaction of the acrylonitrile dimer and the catalyst at the bottom of the second distillation column (300) is prevented, thereby improving the recycling rate of the phosphorus catalyst within the above range.

After the above step S30, the residual mixture in the second distillation column (300) may contain an ionic liquid together with an acrylonitrile dimer and a phosphorus catalyst. In this way, by using the ionic liquid as a reaction solvent in the production of the acrylonitrile dimer, it is possible to minimize the additional reaction of the acrylonitrile dimer and the phosphorus catalyst at the bottom of the second distillation column (300) without evaporating, thereby minimizing the generation of acrylonitrile oligomers and polymers.

According to one embodiment of the present invention, in the method for producing an acrylonitrile dimer, if necessary, a distillation column (not shown), a condenser (not shown), a reboiler (not shown), a pump (not shown), a compressor (not shown), a mixer (not shown), and a separator (not shown) may be additionally installed.

Above, the method for producing an acrylonitrile dimer according to the present invention has been described and illustrated in the drawings. However, the above description and the illustration in the drawings describe and illustrate only the core components for understanding the present invention, and in addition to the processes and devices described and illustrated in the drawings, processes and devices not described or illustrated separately can be appropriately applied and utilized to carry out the method for producing an acrylonitrile dimer according to the present invention.

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 can be made within the scope and technical idea of the present invention, and the scope of the present invention is not limited to these examples alone.

Example

Example 1

As shown in the process flow diagram in FIG. 1, 0.6 mL of acrylonitrile monomer (AN), 98.9 μL of a phosphorus catalyst of the following chemical formula 1-2 (Sigma Aldrich, Ethyl diphenylphosphinite), 0.2 mL of isopropyl alcohol (IPA, ≥99.5%), and 2 mL of 1-butyl-4-methylpyridinium tetrafluoroborate (Tokyo Chemical Industry Co., Ltd., 1-butyl-4-methylpyriidinium Tetrafluoroborate, ≥98%) as an ionic liquid having a water content of about 3000 ppm were supplied to a reactor (100), and an acrylonitrile dimerization reaction was performed at a temperature of 60° C. for 24 hours to obtain an acrylonitrile dimerization reaction product.

The water content of the above ionic liquid was measured using a Karl-Fischer Titrator (Metrohm 917 Coulometer) and HYDRANAL reagent. First, 100 mL of HYDRANAL Coulomat AG solution was filled into the measuring cell in the Karl-Fischer Titrator. After pretreatment, the drift (water titration per minute) was reduced to 20 μg/min and waited until the value stabilized. The ionic liquid was collected in an environment where contact with the outside air was minimized and its weight was measured using a balance. The ionic liquid collected using a syringe was added to the cell where the pretreatment was completed, the syringe weight was weighed, and then water titration was performed. The titration was terminated when the drift over time reached the drift immediately before the sample was added. At this time, the weight of the ionic liquid (m _IL ), the Drift (W _i ) just before sample introduction, the Drift according to the time measured during sample titration (W(t)), and the measurement time (t) were checked to calculate the moisture content (c) in the ionic liquid using the following mathematical formula 1. When introducing the sample into the measurement cell, if the introduction is too slow, the error due to the moisture introduced during sample introduction may be large, so the measurement was performed with caution.

[Mathematical formula 1]

[Chemical Formula 1-2]

Then, the acrylonitrile dimerization reaction product was supplied to the first distillation column (200), and the temperature of the first distillation column (200) was controlled to 40° C. and the pressure to 40 mbar, thereby separating isopropyl alcohol, which is a low boiling point substance, and acrylonitrile monomer from the top discharge stream of the first distillation column (200).

Then, the bottom discharge stream of the first distillation column (200) was supplied to the second distillation column (300), and the temperature of the second distillation column (300) was controlled to 100° C. to 150° C., and the pressure was reduced to 6 mbar or less, thereby separating an acrylonitrile dimer from the top discharge stream of the second distillation column (300), and separating an ionic liquid and a phosphorus catalyst from the bottom discharge stream. At this time, it was confirmed that the acrylonitrile dimer included 1,4-dicyanobutene.

Example 2

In the above Example 1, before supplying 1-butyl-4-methylpyridinium tetrafluoroborate to the reactor (100), ethyl acetate The same method as Example 1 was performed, except that 1-butyl-4-methylpyridinium tetrafluoroborate with a water content of 10 ppm, which was obtained by mixing 6 mL of ethanol, adding 2 g of molecular sieve (Daejung Hwageum, Molecular sieve 4A 4-8 mesh beads), maintaining for 48 hours, and then evaporating ethyl acetate under reduced pressure to 1 mbar, was used.

Comparative example

Comparative example 1

As shown in the process flow diagram in Fig. 1, 0.6 mL of acrylonitrile monomer (AN), 98.9 μL of the phosphorus catalyst of the chemical formula 1-2, 0.2 mL of isopropyl alcohol (IPA, ≥99.5%), and 2 mL of toluene (Tol, ≥99.8%) were supplied to the reactor (100), and an acrylonitrile dimerization reaction was performed at a temperature of 60° C. for 24 hours to obtain an acrylonitrile dimerization reaction product.

Then, the acrylonitrile dimerization reaction product was supplied to the first distillation column (200), and the temperature of the first distillation column (200) was controlled to 40° C. and the pressure to 40 mbar, thereby separating a portion of isopropyl alcohol and toluene, which are low-boiling point substances, and the acrylonitrile monomer from the top discharge stream of the first distillation column (200).

Then, the bottom discharge stream of the first distillation column (200) was supplied to the second distillation column (300), and the temperature of the second distillation column (300) was controlled to 100° C. to 150° C., and the pressure was reduced to 6 mbar or less, thereby separating toluene and acrylonitrile dimer from the top discharge stream of the second distillation column (300), and separating the phosphorus catalyst from the bottom discharge stream. At this time, it was confirmed that the acrylonitrile dimer included 1,4-dicyanobutene.

Experimental example

Experimental example 1

The conversion rate into acrylonitrile dimer and the linear selectivity of acrylonitrile dimer for the acrylonitrile dimerization reaction products according to Examples 1 to 2 and Comparative Example 1 were analyzed by gas chromatography (GC). Specifically, in the case of Examples 1 and 2, since a large amount of ionic liquid having a very low vapor pressure was contained in the acrylonitrile dimerization reaction product, which may reduce the stability of the GC analysis column, 3 mL of toluene was mixed with 1 mL of the acrylonitrile dimerization reaction product, and when phase separation occurred, the supernatant (toluene phase) was collected and analyzed. In addition, the acrylonitrile dimerization reaction product in Comparative Example 1 was directly analyzed by GC. The analysis method is as follows, and the results are shown in Table 1 below.

GC Analysis: Using GC-FID, the mass of each component contained in a constant mass sample was quantitatively analyzed. At this time, the temperature of the column was increased from 40℃ to 280℃, and the type of component was identified based on the retention time of the peak that appeared, and the area of the peak was converted into the mass of the component.

Conversion rate: The reduction rate of the mass of acrylonitrile monomer (m _{AN,t ) after the reaction compared to the mass of acrylonitrile monomer (m AN,t0 )} before the acrylonitrile dimerization reaction was measured using the following mathematical formula 2.

[Mathematical formula 2]

(m _AN,t0 -m _AN,t )/m _AN,t0 x 100

Linear selectivity: The mass fraction of 1,4-dicyanobutene, a linear product (m _DCB ), among the total mass of acrylonitrile dimer (m _DCB +m _MGN ) was measured using the following mathematical formula 3.

[Mathematical Formula 3]

m _DCB /(m _DCB +m _MGN ) x 100

Example 1 Example 2 Comparative Example 1 Conversion rate (%) 40.6 54 75.2 Linear selectivity (%) 96 94 96

Referring to Table 1 above, it was confirmed that Example 1 using an ionic liquid as a reaction solvent, as in the present invention, had an equivalent to superior level of selectivity for linear acrylonitrile dimer compared to Comparative Example 1 using conventional toluene.

Additionally, in the case of Example 2, where an ionic liquid with a low moisture content was used as a reaction solvent, it was confirmed that the conversion rate increased somewhat.

Experimental example 2

The acrylonitrile dimer content, active phosphorus catalyst content, and oligomer content in Example 1 and Comparative Example 1 were measured using the following methods and are shown in Table 2 below.

Method for measuring acrylonitrile dimer content: After measuring the weight of the obtained product from the top of the second distillation column, the content of acrylonitrile dimer contained in the sample was measured using GC-FID.

Method for Measuring the Content of Active Phosphorus Catalyst and Oligomer: In the case of Example 1, the weight of the obtainable from the bottom of the second distillation column was measured, toluene was added to cause phase separation, and the weights of the supernatant, the lower layer, and the solid were measured, respectively. Then, the contents of the phosphorus catalyst and oligomer (including trimers and tetramers) in the supernatant were measured using GC-FID. In addition, in the case of Comparative Example 1, the weight of the obtainable from the bottom of the second distillation column was measured, and toluene was added to dissolve it. Then, the insoluble substance was separated through a filter, dried, and the weight was measured. Then, the contents of the phosphorus catalyst and oligomer (including trimers and tetramers) in the toluene solution were measured using GC-FID.

Example 1 Example 2 Comparative Example 1 Acrylonitrile dimer content (g) in the top of the second distillation column 0.116 0.156 0.087 Acrylonitrile dimer content (g) in the bottom harvest of the second distillation column 0.034 0.050 0.01 Active transfer catalyst (%) 60 80 40 Oligomer content (g) 0.030 0.050 0.241

Referring to Table 2 above, in Examples 1 and 2 using an ionic liquid as a reaction solvent, as in the present invention, it was confirmed that the content of the acrylonitrile dimer finally obtained increased by about 1.5 to 2 times or more compared to Comparative Example 1 using conventional toluene. This result is because toluene was used instead of the ionic liquid in Comparative Example 1, and thus, toluene was included together with the acrylonitrile dimer in the upper discharge stream of the second distillation column (300) due to the azeotrope between toluene and the acrylonitrile dimer.

In addition, in Examples 1 and 2, it was confirmed that the active phosphorus catalyst obtained from the bottom of the second distillation column (300) increased by about 1.5 to 2 times or more compared to Comparative Example 1 by 60 to 80% or more of the amount introduced into the acrylonitrile dimerization reaction. This is because, in the absence of the ionic liquid in Comparative Example 1, the active phosphorus catalyst is converted to an inactive state in the process of forming an oligomer due to the additional reaction of the acrylonitrile dimer and the phosphorus catalyst at the bottom of the second distillation column (300).

Through this, it can be seen that in the present invention, by using an ionic liquid as a reaction solvent for the acrylonitrile dimerization reaction, the yield of acrylonitrile dimer increases and the recyclability of the phosphorus catalyst is improved.

In addition, in Examples 1 and 2, it was confirmed that the ionic liquid was present together with the acrylonitrile dimer and the phosphorus catalyst at the bottom of the second distillation column (300), thereby preventing the continuous reaction of the acrylonitrile dimer and the phosphorus catalyst, thereby suppressing the production of oligomers and polymers.

In comparison, in Comparative Example 1, a high concentration of acrylonitrile dimer and a phosphorus catalyst were present at the bottom of the second distillation column (300) without an ionic liquid, and thus, the content of acrylonitrile dimer was reduced compared to Example 1 through additional reaction of the acrylonitrile dimer and the phosphorus catalyst, and about 4.8 to 8 times more oligomers were formed, confirming that most of the residual mixture was oligomers.

100: Reactor
200: 1st distillation column
300: Second distillation column

Claims (12)

A step of removing moisture from an ionic liquid;
A step (S10) of supplying an acrylonitrile monomer, a phosphorus catalyst, an alcohol solvent, and an ionic liquid from which moisture has been removed to a reactor to cause a dimerization reaction to produce a single-phase dimerization reaction product;
Step (S20) of supplying a reactor discharge stream containing the dimerization reaction product to a first distillation column, separating an alcohol solvent and unreacted acrylonitrile monomer from the top discharge stream, and supplying a bottom discharge stream containing an acrylonitrile dimer, an ionic liquid, and a phosphorus catalyst to a second distillation column; and
A step (S30) of separating an upper discharge stream containing an acrylonitrile dimer from the second distillation column and separating a bottom discharge stream containing an ionic liquid and a phosphorus catalyst,
The above ionic liquid contains a cation and an anion, and the ionic liquid contains a pyridinium-based cation as a cation and a tetrafluoroborate anion as an anion.
The step of removing moisture from the above ionic liquid is:
It comprises a step of preparing a mixed solution by mixing an ionic liquid and a second solvent; a step of removing moisture by introducing a porous material into the mixed solution; and a step of separating an ionic liquid from the mixed solution.
A method for producing an acrylonitrile dimer, wherein the moisture content in the ionic liquid from which moisture has been removed is 50 ppm or less. In the first paragraph,
The above-mentioned catalyst is a method for producing an acrylonitrile dimer represented by the following chemical formula 1:
[Chemical Formula 1]

In the above chemical formula 1,
R represents an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a cycloalkyl group having 3 to 8 carbon atoms,
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 and m are each independently an integer from 1 to 2, and the sum of n and m is 3. In the first paragraph,
A method for producing an acrylonitrile dimer, wherein the alcohol solvent comprises at least one selected from the group consisting of isopropyl alcohol, methyl alcohol, and cyclohexane alcohol. delete delete In the first paragraph,
A method for producing an acrylonitrile dimer, wherein the pyridinium-based cation comprises at least one selected from the group consisting of 1-butyl-4-methylpyridinium and 1-ethyl-3-methylpyridinium. In the first paragraph,
A method for producing an acrylonitrile dimer, wherein the volume ratio of the alcohol solvent and the ionic liquid supplied to the above reactor is 1:5 to 20. delete delete In the first paragraph,
A method for producing an acrylonitrile dimer, wherein in the step S20, the operating temperature of the first distillation column is 10° C. to 60° C., and the operating pressure is 1 mbar to 200 mbar. In the first paragraph,
A method for producing an acrylonitrile dimer, wherein in the step S30, the operating temperature of the second distillation column is 100° C. to 200° C., and the operating pressure is 0.005 mbar to 80 mbar. In the first paragraph,
A method for producing an acrylonitrile dimer, wherein the content of the phosphorus catalyst separated in step S30 is 0.5 to 0.95 relative to the content of the phosphorus catalyst supplied to the reactor in step S10.