Patent Application
20230192599
The present invention relates to a method for preparing azo compound, and more specifically, to a method for preparing azo compound from a hydrazo compound.
An azo compound is a compound having R—N═N—R′ (azo group) (i.e., a structure in which two nitrogen atoms are double bonded), in which R and R′ are each aryl or alkyl. An azo group is a chromophore, and an azo compound including the azo group exhibits colors such as red, orange, and yellow, and thus has high utility value as a dye and is widely used as a colorant of color filters used in display devices (e.g., liquid crystal display panels, electroluminescence, plasma display panels, etc.).
Meanwhile, azodicarbonamide (ADCA), which is a kind of an azo compound, is currently the most commonly used material of foaming agent. The material of foaming agent material is an additive for preparing a porous foam by mixing with a synthetic resin. Azodicarbonamide has a self-extinguishing property and is characterized by non-toxicity, and is used for the purpose of weight lightening, a cushioning property, buoyancy, absorbency, decorativeness, tactility, cost reduction, and dimensional stability of products. Additionally, the foaming of azodicarbonamide is mainly used in polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), rubber, an ethylene-vinyl acetate copolymer (EVA), polystyrene (PS), polyurethane (PU), transparent silicone, etc. Additionally, the azodicarbonamide is known as an excellent foaming agent because nitrogen gas is rapidly generated when heated, and decomposition products are non-flammable and non-toxic. Additionally, the azodicarbonamide is also used as a thermostat or bleaching agent for wheat flour (45 ppm or less, US FDA standard).
Meanwhile, azodicarbonamide is usually produced by oxidizing hydrazodicarbon amide (HDCA) with chlorine (Cl2). In particular, a conventional method of producing azodicarbonamide was to directly supply chlorine to reactants (existing method).
However, according to the existing method, an excess content of chlorine must be used, and since hydrochloric acid (HCl), a strong acid, is produced as a by-product together with azodicarbonamide, there is a problem in that a large content of alkali compound is required for neutralization of the by-product (wastewater). Accordingly, studies have been focused on the development of a method for generating chlorine (Cl2) by electrolysis. However, this method also had a problem in that it is essential between the positive electrode and negative electrode compartments be separated within a reactor (electrolyzer) through a separator so as to prevent sodium hydroxide (NaOH), a by-product generated in the negative electrode compartment, from decomposing the azodicarbonamide generated in the positive electrode compartment, and a problem in that it requires a large cost for the treatment of the by-product (wastewater), and thus have not been used.
Referring to
According to the conventional technology of
The technical object to be achieved in the present invention is to provide a method for producing an azo compound, which, by using a predetermined halogen compound (MaXb) in producing an azo compound from a hydrazo compound, does not require continuous introduction of a chlorine source, etc., can significantly reduce the burden of treatment of wastewater and by-products, and can realize a high conversion rate and a high yield.
Additionally, the technical object to be achieved in the present invention is to provide a method for producing an azo compound, which does not require the use of a separator even if the electrolysis method is used and can reduce power consumption compared to the conventional technology.
The problems to be solved in the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.
According to embodiments of the present invention for achieving the above objects, there is provided a method for preparing azo compound, which includes: a first step for producing an Xb molecule by electrolyzing, in a reaction system, a first solution including a hydrazo compound and at least one type of MaXb; a second step for oxidizing the hydrazo compound with the generated Xb molecule to obtain a second solution including an azo compound, MaXb, and HX; a third step for discharging the second solution outside the reaction system, and separating therefrom a third solution including MaXb and HX to obtain a solid azo compound; and a fourth step for introducing the third solution and an additional hydrazo compound equivalent to the hydrazo compound into the reaction system, and electrolyzing a fourth solution including the additional hydrazo compound, MaXb, and HX to produce an Xb molecule, wherein the fourth step, the second step, and the third step are collectively defined as a single cycle, and the cycle is performed repeatedly, and wherein: X is a halogen element; M is at least one selected from hydrogen, Li, Na, K, Mg, Ca, Mn, Fe, Ni, Cu, Ag, Zn, Sn, Zr, and Ti, or at least one selected from a primary ammonium ion, a secondary ammonium ion, and a tertiary ammonium ion; the H is hydrogen; and a and b are each independently any one integer from 1 to 4.
The content of the at least one type of MaXb initially introduced into the reaction system in the first step may be 1 wt % to 30 wt % based on the total weight of the first solution.
The MaXb may include at least one of a Cl2 precursor and a Br2 precursor.
The content of the Cl2 precursor may be 3 wt % to 15 wt % based on the total weight of the first solution.
The content of the Br2 precursor may be 0.05 wt % to 5 wt % based on the total weight of the first solution.
The method for preparing azo compound may satisfy the following Relational Equation (1).
In Relational Equation (1) above, α is the content (wt %) of MaXb based on the total weight of the first solution, and β is the reaction temperature (° C.) of the method for producing an azo compound.
The method for preparing an azo compound may satisfy the following Relational Equation (1-1).
In Relational Equation (1-1) above, α is the content (w %) of MaXb based on the total weight of the first solution, and β is the reaction temperature (° C.) of the method for producing an azo compound.
The concentration of HX can be maintained uniformly in the first to third solutions from the starting time of the first step to the ending time of the third step.
The reaction system may include a solution of any one of the first to fourth steps; a positive electrode immersed in the solution; and a negative electrode immersed in the solution; and the solution around the positive electrode and the negative electrode may be acidic.
The negative electrode may be in direct contact with any one or more of the hydrazo compound and the azo compound.
The hydrazo compound may be hydrazodicarbonamide (HDCA) and the azo compound may be azodicarbonamide (ADCA).
The azo compound may be present in a slurry state before separating the third solution in the third step.
According to another embodiment of the present invention for achieving the above objects, there is provided a method for preparing azo compound, which includes: a first step for producing an Xb molecule by electrolyzing, in a reaction system, a first solution including a hydrazo compound and at least one type of MaXb; a second step for oxidizing the hydrazo compound with the generated Xb molecule to obtain a second solution including an azo compound, MaXb, and HX; and a third step for discharging the second solution outside the reaction system, and separating therefrom a third solution including MaXb and HX to obtain a solid azo compound; wherein the pH of the first solution to the third solution in the first step to third step reaction systems is uniform, and wherein: X is a halogen element; M is at least one selected from hydrogen, Li, Na, K, Mg, Ca, Mn, Fe, Ni, Cu, Ag, Zn, Sn, Zr, and Ti, or at least one selected from a primary ammonium ion, a secondary ammonium ion, and a tertiary ammonium ion; the H is hydrogen; and a and b are each independently any one integer from 1 to 4.
According to embodiments of the present invention, in a method for producing an azo compound from a hydrazo compound, a method for producing an azo compound with a high conversion rate and a high yield can be realized by using a predetermined halogen compound (MaXb), which does not require continuous introduction of a chlorine source, etc., and can significantly reduce the burden of treatment of wastewater and by-products.
Additionally, according to the embodiments of the present invention, even if the electrolysis method is used, it is unnecessary to use a separator, and it is possible to implement a device for manufacturing an azo compound capable of reducing power consumption compared to the conventional technology. Therefore, the manufacturing process and process management can be facilitated, and manufacturing cost can be reduced, and productivity can be improved.
Hereinafter, preferred embodiments of the present inventionwill be described in detail with reference to the accompanying drawings.
Examples of the present invention to be described below are provided to more clearly explain the present invention to those skilled in the art, and the scope of the present invention is not limited by the following Examples, and the following Examples can be modified into various other forms.
The terms used herein are used to describe specific embodiments, and not to limit the present invention. As used herein, terms in a singular form may include a plural form unless the context clearly dictates otherwise. Additionally, as used herein, the terms “comprise” and/or “comprising” refer to a referenced shape, step, number, action, member, element, and/or existence of these groups and do not exclude the presence or addition of one or more other shapes, steps, numbers, actions, members, elements, and/or groups thereof. Additionally, as used herein, the term “connection” not only means that certain members are directly connected, but also includes indirectly connected members with other members interposed therebetween.
Additionally, as used herein, when a member is located “on” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members. As used herein, the term “and/or” includes any one and any combination of one or more of those listed items. Additionally, as used herein, terms such as “about”, “substantially”, etc. are used in the meaning of the range or close to the numerical value or degree, in consideration of inherent manufacturing and material tolerances, and are used to prevent the infringer from unfairly using the disclosure, in which the exact or absolute figures are mentioned, provided to help the understanding of the present application.
The size or thickness of the regions or parts shown in the accompanying drawings may be slightly exaggerated for clarity and convenience of description. Like reference numerals refer to like elements throughout the detailed description.
Referring to
First step (S10): a step in which a first solution containing a hydrazo compound and at least one kind of MaXb is introduced into the reaction system, and an electrolysis process is performed on the solution so as to produce Xb molecules
Second step (S20): a step in which the hydrazo compound is oxidized with the Xb molecules produced so as to obtain a second solution containing an azo compound, MaXb, and HX
Third step (S30): a step in which the second solution is discharged to the outside of the reaction system, and a third solution containing MaXb and HX is separated therefrom so as to obtain a solid azo compound
Fourth step (S40): a step in which a hydrazo compound equivalent to the hydrazo compound (an additional hydrazo compound) and the third solution are re-introduceed into the reaction system, and an electrolysis process is performed on a fourth solution containing the hydrazo compound, MaXb, and HX so as to produce Xb molecules
Additionally, in the method for producing an azo compound according to the present embodiment, the fourth step (S40), the second step (S20), and the third step (S30) may be regarded as one cycle and the cycle may be performed repeatedly. That is, after the fourth step (S40), a step corresponding to the second step (S20) and a step corresponding to the third step (S30) may be performed, and after performing the step corresponding to the fourth step (S40) again, a step corresponding to the second step (S20) and a step corresponding to the third step (S30) may be further performed. This process can be performed repeatedly. That is, in the case of a batch reaction, the first step (S10), the second step (S20), the third step (S30), and the fourth step (S40) are sequentially performed. In the case of the batch reaction, when the first to fourth steps (S10 to S40) are performed simultaneously, there may be a problem in terms of reaction stability. Additionally, in the case of a continuous reaction, the reaction may be sequentially performed in the order of the fourth step (S40), the second step (S20), and the third step (S30) and simultaneously. In this case, electrical energy can be continuously applied without interruption.
Here, the X may be a halogen element. For example, the X may include at least one of Cl, Br, and I. The M may be at least one selected from hydrogen, Li, Na, K, Mg, Ca, Mn, Fe, Ni, Cu, Ag, Zn, Sn, Zr, and Ti, or at least one selected from a primary ammonium ion, a secondary ammonium ion, and a tertiary. The ammonium ion may include NH4 (NH4). Meanwhile, H represents hydrogen, and a and b may each independently be an integer of any one of 1 to 4.
Hereinafter, each of the above steps (S10 to S40) will be described in more detail.
The first step (S10) may be performed such that a first solution containing a hydrazo compound and at least one kind of MaXb is introduceed into the reaction system, and an electrolysis process is performed on the first solution to produce Xb molecules. In particular, MaXb may be a halogen compound. In an embodiment, the MaXb may include any one or more of a Cl2 precursor and a Br2 precursor. For example, the MaXb may include a Cl2 precursor alone, a Br2 precursor alone, or include both a Cl2 precursor and a Br2 precursor. In particular, the Cl2 precursor or the Br2 precursor refers to a material capable of providing Cl2 or Br2 through a certain reaction, for example, to a material capable of forming Cl2 or Br2 by an electrolysis reaction. The MaXb may be, for example, HCl. This is the case where M is H and X is Cl in MaXb. Additionally, the MaXb may include two or more materials, and may include, for example, HCl and HBr. This is the case where ‘M is H and X is Cl’ and ‘M is H and X is Br’ are combined in MaXb. In the case of a Br-based compound in which X is Br in MaXb, it is introduceed as an electrolyte, but it can also serve as a catalyst. In another embodiment, it may include HCl and NaCl. This is the case where ‘M is H and X is Cl’ and ‘M is Na and X is Cl’ are combined in MaXb. However, the above compounds are exemplary, and other compositions of MaXb may be used. Meanwhile, since M may be H, MaXb may be the same as HX.
The first solution may include, for example, water as a solvent. However, the type of solvent is not limited to water and may be variously changed. For example, the solvent may include at least one among water, alcohol, and an organic solvent. In the first solution, the hydrazo compound may exist in a slurry state or in a dissolved state. Even if the hydrazo compound exists in a slurry state, the hydrazo compound can be regarded as a partial constitution of a solution or a constitution included in the solution in a broad sense.
In the first step (S10), Xb molecules may be produced by the electrolysis process on MaXb. The process may be, for example, as shown in Chemical Formula 1 below.
M
a
X
b
→M
a
+X
b [Chemical Formula 1]
During the electrolysis process, Ma may be produced in the negative electrode and Xb may be produced in the positive electrode. If MaXb includes HCl, Ma may be H2 (i.e., a hydrogen molecule), and Xb may be Cl2 (i.e., a chlorine molecule). H2 and Cl2 may be gases.
If, M in the MaXb is a metal ion or ammonium ion, Chemical Formula 1 may be changed. In a specific example in Chemical Formula 1, when the MaXb is 2LiCl, 2Li+ and Cl2 gases may be produced by electrolysis, and when the MaXb is 2NH4Cl, 2NH4+ and Cl2 gases may be produced by electrolysis. Therefore, Chemical Formula 1 above is exemplary, and may vary depending on the material of MaXb being used. Additionally, when the solvent of the solution is water (H2O), 2H2O may be decomposed into H2 and 2OH− by electrolysis. In this case, the 2Li+ may react with 2OH− to become 2LiOH, and the 2NH4+ may react with 2OH− to become 2NH4OH.
The second step (S20) may be performed such that the hydrazo compound is oxidized with the Xb molecules produced to obtain a second solution containing an azo compound, MaXb, and HX. The reaction in this second step (S20) may be as shown in Chemical Formula 2 below.
a hydrazo compound+Xb→an azo compound+2HX [Chemical Formula 2]
In the hydrazo compound, hydrogen (H) may react with Xb to form 2HX, and the hydrazo compound may be converted into an azo compound.
The second solution obtained through the second step (S20) may be a solution containing the azo compound, MaXb, and HX. In particular, MaXb may be a material remaining after consumption of some of the MaXb introduceed in the first step (S10). For example, when MaXb includes HCl and HBr in the first step (S10), the HBr may simultaneously serve as a catalyst and may remain without being consumed after participating in the reaction, and thus it may remain in the form of MaXb in the second step (S20). There is also the possibility that some of the HCl remains. In this regard, it is also possible that the MaXb in the second step (S20) corresponds to a part of MaXb introduceed in the first step (S10). In Chemical Formula 2, when the Xb molecule is Cl2, 2HX may be 2HCl. However, the material of 2HX is not limited to 2HCl and may vary. When the Ma in MaXb is H, it may be HX (“first HX”), in which the “first HX” does not refer to HX (“second HX”) produced together with the azo compound but refers to an HX different from the “second HX”. In the second solution of the second step (S20), the azo compound may exist in a slurry state or in a dissolved state. Even if the azo compound exists in a slurry state, the azo compound can be regarded as a part of a solution or a constitution included in the solution in a broad sense.
The third step (S30) may be performed such that the second solution is discharged to the outside of the reaction system, and a third solution containing MaXb and HX is separated therefrom to obtain a solid azo compound. The second solution obtained in the second step (S20) is discharged to the outside of the reaction system, and then a third solution containing MaXb and HX is separated from the second solution to obtain a solid azo compound. This may be referred to as a dehydration and drying process to obtain a solid azo compound. Through this, a solid azo compound can be obtained, and simultaneously, a third solution containing MaXb and HX can be obtained by separation. The solution containing MaXb and HX separated in this way may be re-introduceed into the reaction system in a subsequent process to be recycled.
That is, when HX is electrolyzed, Xb molecules are produced, and simultaneously, the Xb molecules oxidize the hydrazo compound to produce an azo compound. Additionally, since HX is produced together with the azo compound as a result of the oxidation reaction, the concentration of HX can be uniformly maintained from the starting time of the second step (S20) to the ending time of the third step (S30). That is, the concentration of the HX in the first to third solutions can be uniformly maintained from the starting time of the first step S10 to the ending time of the third step S30. Therefore, when the solution containing the MaXb and HX separated in the fourth step (S40) to be described later is re-introduceed after the completion of the third step, the separated solution can be introduceed as-is to proceed with the reaction, and it can be re-introduceed after replenishing only the content of the loss occurred in the separated solution.
The fourth step (S40) may be performed such that a hydrazo compound equivalent to the hydrazo compound (an additional hydrazo compound) and the third solution are introduceed into the reaction system, and an electrolysis process is performed on an additional fourth solution containing the hydrazo compound, MaXb, and HX to produce Xb molecules.
Meanwhile, the term “equivalent” does not mean “the same content” but means “the same compound”.
In the fourth step (S40), Xb molecules may be produced by the electrolysis process for the MaXb and HX. The process may be, for example, as shown in Chemical Formulas 3-1 and 3-2 below.
M
aXb→Ma+Xb [Chemical Formula 3-1]
2HX→H2+X2 [Chemical Formula 3-2]
During the electrolysis process, Ma and H2 may be produced in the negative electrode, and Xb and X2 may be produced in the positive electrode. In particular, Xb may include, for example, Cl2. In the case of Chemical Formula 3-1, as described above in Chemical Formula 1, the chemical formula may be changed depending on the material of MaXb being used.
The process of producing Xb molecules in the fourth step (S40) may correspond to or similar to the process of producing Xb molecules in the first step (S10). Accordingly, the fourth step, the second step, and the third step may be regarded as one cycle and the cycle may be performed repeatedly. After the fourth step (S40), a step corresponding to the second step (S20) and a step corresponding to the third step (S30) may be performed, and after performing the step corresponding to the fourth step (S40) again, a step corresponding to the second step (S20) and a step corresponding to the third step (S30) may be further performed. This process may be performed repeatedly.
For example, when HCl is used as a precursor of chlorine (Cl2), the HCl is electrolyzed to produce chlorine (Cl2) and simultaneously the chlorine (Cl2) oxidizes the hydrazo compound. As the hydrazo compound is converted into an azo compound through an oxidation reaction, HCl is produced again. Therefore, the concentration of HCl introduceed at the starting time of the reaction of the first step does not change even though the electrolysis and oxidation reactions are performed repeatedly. That is, the azo compound produced at the ending time of the reaction in the third step and the solution obtained by separating the azo compound can be reused.
Additionally, the separated azo compound may include a trace content of a reaction solution containing HCl, and a water washing process may be performed using a large content of water to remove the trace content of the reaction liquid. The low concentration HCl solution produced through the above process can be concentrated again to a high concentration and reused in the electrolysis reaction of the present invention. The above-described HCl is merely described as an embodiment, and is not limited thereto.
According to this embodiment of the present invention, since the third solution separated in the third step (S30) is recycled and used continuously (repeatedly), there is no need to continuously introduce a new halogen source (e.g., a chlorine source), and the burden of treatment of wastewater and by-products can be significantly reduced.
The content of MaXb to be initially introduceed into the reaction system in the first step (S10) may be about 1 wt % to about 30 wt % based on the total weight of the first solution. For example, the content of MaXb to be initially introduceed in the first step (S10) may be about 1 wt % to 20 wt % based on the total weight of the solution containing the hydrazo compound, MaXb, and HX. When the content of MaXb initially introduceed into the reaction system in the first step (S10) is less than 1 wt %, the content of the electrolyte is insufficient and the voltage rises, and thus heat is produced, thereby making it difficult to proceed a substantial electrolysis process, whereas when it exceeds 30 wt %, the acid concentration in the solution becomes thick, and thus the production of an azo compound is prevented, and the electrodes where the electrolysis process proceeds may be damaged. The content of MaXb to be initially introduceed in in the first step (S10) may be determined in consideration of the total weight of the first solution. The content of MaXb to be initially introduceed in the first step (S10) may be relatively small. The manufacturing process of an azo compound according to the embodiment may be proceeded using a relatively small content of MaXb only in the initial step (i.e., S10).
When the MaXb to be introduceed in the first step (S10) includes a Cl2 precursor, the content of the Cl2 precursor may be about 3 wt % to 15 wt % based on the total weight of the first solution. When the content of the Cl2 precursor initially introduceed into the reaction system in the first step (S10) is less than 3 wt %, the voltage is increased due to insufficient content of electrolyte, and subsequently, heat is produced thereby making it difficult to perform an actual electrolysis process, whereas when it exceeds 15 wt %, the acid concentration in the solution becomes thick, and thus the production of an azo compound is prevented, and the electrodes where the electrolysis process proceeds may be damaged.
When the MaXb to be introduceed in the first step (S10) includes both the Cl2 precursor and the Br2 precursor, the content of the Cl2 precursor may be the same as described above, and the content of the Br2 precursor may be 0.05 wt % to 5 wt %, preferably 0.1 wt % to 3 wt %, based on the total weight of the first solution. When the content of the Br2 precursor initially introduceed into the reaction system in the first step (S10) is less than 0.05 wt %, the decomposition temperature of the azo compound being produced is low, and thus the quality may be significantly reduced, whereas when it exceeds 5 wt %, the production yield of the azo compound may be significantly reduced and the amount of electric power per 1 g of the azo compound may be increased.
Additionally, as long as it is a material capable of producing Xb molecules by electrolysis in the first step (S10), other materials may also be used even if it is not the above-described MaXb material.
Meanwhile, the X (a halogen element) in the HX mentioned in the second step (S20), the third step (S30), and the fourth step (S40) may be, for example, at least one of Cl, Br, and I. In other words, the HX may include, for example, at least one selected from the group consisting of HCl, HBr, and HI.
The manufacturing method of the azo compound according to this embodiment may satisfy the following Relational Equation (1), preferably, the following relational equation (1-1).
In Relational Equation (1-1) above, α is the content (wt %) of MaXb based on the total weight of the first solution, and β is the reaction temperature (° C.) of the method for preparing an azo compound.
When the numerical value according to the above Relational Equation (1) is less than 0.1 or exceeds 9.5, the electric power consumption per 1 g of the azo compound prepared according to the method for preparing an azo compound according to the present embodiment may be significantly increased, and the quality of the azo compound may be deteriorated by significantly lowering or significantly increasing the decomposition temperature of the azo compound.
The reaction system used in an embodiment of the present invention may include a solution containing the MaXb, a positive electrode immersed in the solution, and a negative electrode immersed in the solution. Here, the solution may correspond to the solution in any one of the first to fourth steps (S10 to S40). Accordingly, the solution may further include at least one of a hydrazo compound, HX, an azo compound, and a solvent.
In an embodiment of the present invention, the solution may further include an additive if necessary. The additive may be at least one selected from the group consisting of organic acids or inorganic acids, and is not limited as long as it is a material capable of serving as an electrolyte by being dissolved in a solution.
The positive electrode and the negative electrode may be electrodes for the electrolysis reaction in the first step (S10) and the fourth step (S40). For example, the positive electrode may include at least one among titanium (Ti) and alloys thereof, Hastelloy, platinum (Pt) and alloys thereof, stainless steel (e.g., SUS), iridium (Ir) and alloys thereof, an iridium (Ir)-coated metal, ruthenium (Ru) or oxides thereof, graphite, and carbon lead. The negative electrode may include at least one among stainless steel (e.g., SUS), titanium (Ti) and alloys thereof, and aluminum (Al) and alloys thereof. However, the materials of the positive electrode and the negative electrode mentioned above are exemplary, and the present application is not limited thereto. As the material of the positive electrode, an electrode where a noble metal (e.g., gold, silver, platinum, ruthenium, etc.) is coated on a noble metal substrate, a minor metal substrate (e.g., titanium, chromium, nickel, manganese, etc.), and a non-noble metal substrate (e.g., titanium, stainless steel, iron, Hastelloy, etc.); an electrode where a noble metal is coated on a non-metal substrate (e.g., olefin resin, engineering resin, a carbon-based substrate, etc.); a composite electrode coated with platinum and a metal oxide (e.g., iridium oxide or ruthenium oxide); the coated electrode as described above by a minor metal; etc. may be used. The material of the negative electrode is not particularly limited, and all of the materials exemplified as the material of the positive electrode, general-purpose metals (e.g., iron, copper, and aluminum), stainless steel, Hastelloy, various alloys, and a composite electrode provided with the same may be used. The materials of the positive electrode and the material of the negative electrode are not limited as long as they are an electrode material that do not cause corrosion even in an acidic solution.
The solution around the positive electrode and negative electrode may be “acidic”. The pH of the solution in the reaction system may be uniform or substantially uniform. In the conventional technology, the positive electrode compartment and the negative electrode compartment are separated, and the positive electrode compartment shows the acidity of about pH 1 to pH 4, and the negative electrode compartment shows alkalinity of about pH 11 to pH 14. In contrast, according to an embodiment of the present invention, the pH of the solution in the reaction unit may exhibit a uniform (substantially uniform) acidity as a whole. As the pH of the solution in the reaction system becomes low, the yield of the azo compound produced may increase and the quality of the azo compound may be excellent. The pH may represent an acidity of about pH 1 to pH 4, specifically, an acidity of about pH 1 to pH 2.
Additionally, in an embodiment of the present invention, the negative electrode may be in direct contact with any one or more of the hydrazo compound and the azo compound. In the conventional device as shown in
In the first step (S10) or the fourth step (S40), electrical energy is applied to the reaction unit for the electrolysis, where the electric power applied to the reaction system may be, for example, about 1 W to about 10 W per 1 g of the azo compound. Specifically, the electric power may be about 1.5 W to about 5 W. In this case, for the completion of an electrolysis reaction, for example, it may take about 4 to 6 hours. In a specific embodiment, when a current of about 10 A is applied per 100 g of the hydrazo compound, it may take about 4 to 6 hours. Additionally, electric energy is applied to the reaction system for the electrolysis in the first step (S10) or the fourth step (S40), and the voltage applied to the reaction system may be, for example, about 1 V to 13 V, and specifically, it may be about 2 V to 12 V. The range of the electric power and voltage may be relatively lower than the electric power and voltage used in the device according to the conventional technology described with reference to
In the first step (S10), the hydrazo compound may be introduceed, for example, in a slurry type. Additionally, before separating the solution containing MaXb and HX in the third step (S30), the azo compound may exist, for example, in a slurry state. In this case, there is an advantage in that the hydrazo compound can be more easily converted into the azo compound, and the obtained (synthesized) azo compound can be dehydrated/dried in a relatively simple manner without a complicated process. However, in some cases, the hydrazo compound and/or the azo compound may be in a state dissolved in a solution rather than in a slurry state.
In the method for producing an azo compound according to the embodiments of the present invention described above with reference to
Additionally, the method for preparing an azo compound according to an embodiment of the present invention may be performed at a temperature in the range of 10° C. to 80° C., preferably at a temperature in the range of 10° C. to 45° C. In the azo compound manufacturing method, when the temperature is less than 10° C., the reaction rate may be slow or the reaction may not proceed, whereas when the temperature exceeds 80° C., there may be problems in that the azo compound may be decomposed by heat to thereby decrease the yield or deteriorate the quality, and in that the amount of electric power required per weight of the azo compound to be produced may be significantly increased.
Additionally, the method for preparing an azo compound according to an embodiment of the present invention can achieve a yield close to 100%. For example, a high yield of about 90 to 96% can be achieved. Additionally, the method for preparing an azo compound according to this embodiment can be performed in one reaction system from electrolysis to the synthesis of an azo compound.
The method for producing an azo compound according to another embodiment of the present invention may include the following first to third steps (S10 to S30).
First step (S10): a step in which a first solution containing a hydrazo compound and at least one kind of MaXb is introduceed into the reaction system, and an electrolysis process is performed on the solution so as to produce Xb molecules
Second step (S20): a step in which the hydrazo compound is oxidized with the Xb molecules produced so as to obtain a second solution containing an azo compound, MaXb, and HX
Third step (S30): a step in which the second solution is discharged to the outside of the reaction system, and a third solution containing MaXb and HX is separated therefrom so as to obtain a solid azo compound
The solution around the positive electrode and negative electrode may be “acidic”. The pH of the solution in the reaction system may be uniform or substantially uniform. In the conventional technology, the positive electrode compartment and the negative electrode compartment are separated, and the positive electrode compartment shows the acidity of about pH 1 to pH 4, and the negative electrode compartment shows alkalinity of about pH 11 to pH 14. In contrast, according to an embodiment of the present invention, the pH of the solution in the reaction system may exhibit a uniform (substantially uniform) acidity as a whole. As the pH of the solution in the reaction unit becomes low, the yield of the azo compound produced may increase and the quality of the azo compound may be excellent. The pH may represent an acidity of about pH 1 to pH 4, specifically, an acidity of about pH 1 to pH 2.
Here, the X may be a halogen element. For example, the X may include at least one of Cl, Br, and I. The M may be at least one selected from hydrogen, Li, Na, K, Mg, Ca, Mn, Fe,
Ni, Cu, Ag, Zn, Sn, Zr, and Ti, or at least one selected from a primary ammonium ion, a secondary ammonium ion, and a tertiary. The ammonium ion may include NH4 (NH4+). Meanwhile, H represents hydrogen, and a and b may each independently be an integer of any one of 1 to 4.
For the specific contents of another embodiment of the present invention, the contents described in the above one embodiment may be equally applied.
Referring to
The reaction system may include a negative electrode 60A and a positive electrode 60B immersed in the solution 100. The negative electrode 60A and the positive electrode 60B are for the electrolysis reaction of the solution 100, and at least a portion of them may be immersed in the solution 100. The electrolysis reaction may correspond to the electrolysis in the first step (S10) and the fourth step (S40) of
As the shape of the negative electrode 60A or the positive electrode 60B, a plate material, a punched metal with holes, mesh, porous metal, fiber shape, etc. may be used. The process efficiency can be further improved by variously modifying the shape of the negative electrode 60A or the positive electrode 60B to expand the reaction area. However, the shapes of the negative electrode 60A and the positive electrode 60B are not limited to those described above and other various shapes/structures may be used.
The negative electrode 60A and the positive electrode 60B may be formed as a pair, or may be formed of a plurality of pairs of two or more pairs. For the efficiency of the reaction, it may be more advantageous that the distance between the negative electrode 60A and the positive electrode 60B be close. In an embodiment of the present invention, a separator may not be provided between the negative electrode 60A and the positive electrode 60B. Additionally, the method for connecting the negative electrode 60A and the positive electrode 60B may include a series connection, a parallel connection, or a mixed connection of a series connection and a parallel connection, etc., but is not limited thereto.
Meanwhile, the reaction tank 20 of the reaction system that can be used in the method for producing an azo compound according to an embodiment of the present invention may have an open structure with an open top as shown in
Additionally, as shown in
Referring to
A filtration unit may be included as needed. Impurities that may be included in the reactants can be filtered through the filtration unit.
Additionally, the reaction system may further include a stirrer 70 for stirring a solution 100 as shown in
It is also possible not to use the stirrer 70, and as shown in
The process for preparing an azo compound according to the embodiment of the present invention described with reference to
Referring to
The reaction systemof this embodiment may further include an electrode chamber (i.e., an electrode tank) 55 spaced apart from the reaction tank 25. At least one negative electrode 65A and at least one positive electrode 65B may be provided in the electrode tank 55. One or more pairs of the negative electrode 65A and the positive electrode 65B may be disposed in the electrode tank 55. The negative electrode 65A and the positive electrode 65B are for the electrolysis reaction of the solution 100, and the electrolysis reaction can correspond to the electrolysis in the first step (S10) and the fourth step (S40) with reference to
The reaction system of this embodiment may further include a gas treatment unit 85. The gas treatment unit 85 may be provided at an upper end of the reaction tank 25 and the electrode chamber 55. Various types of gas (e.g., ammonia (NH3) gas, nitrogen (N2) gas, hydrogen (H2) gas, chlorine (Cl2) gas, bromine (Br2) gas, etc.) generated in the process of performing the method for producing an azo compound according to an embodiment of the present invention can be captured and used in a variety of ways.
The reaction system of this embodiment may further include a connection structure which connects the reaction tank 25 and the electrode tank 55. The connection structure may include, for example, a first connecting pipe 35a and a second connecting pipe 35b. The first connecting pipe 35a may be configured to connect a first end of the reaction tank 25 and a first end of the electrode tank 55, and the second connecting pipe 35b may be configured to connect a second end of the reaction tank 25 and a second end of the electrode tank 55. A pump 45 may be installed in the first connecting pipe 35a. The pump 45 may be a kind of circulation pump.
The solution 100 can be circulated within the reaction system by the operation of the pump 45. In other words, by the operation of the pump 45, the solution 100 moves from the reaction tank 25 to the electrode tank 55 through the first connecting pipe 35a, and is then introduceed from the electrode tank 55 back into the reaction tank 25 through the second connecting pipe 35b.
Additionally, the reaction unit of this embodiment may further include a stirrer 75 for stirring the solution 100 in the reaction tank 25. Various types of the stirrer 75 may be used, and an appropriate stirring speed may vary depending on the type of the stirrer 75.
Additionally, as shown in
The process for preparing an azo compound according to the embodiment of the present invention described with reference to
In the case of the reaction system described in
The reaction system excluding the stirrer 75 in
Hereinafter, an azo compound prepared by the method for preparing an azo compound according to an embodiment of the present invention will be described in detail with reference to Examples and Comparative Examples. Additionally, the Examples shown below are an embodiment to help understanding of the present invention, and the scope of the present invention is not limited.
A 500 mL beaker, electrodes, hydrazodicarbonamide (HDCA), distilled water, and MaXb were prepared for an electrolysis reaction. HDCA, distilled water, and MaXb were each weighed and introduceed into the 500 mL beaker according to the contents shown in Table 1 below. Thereafter, the introduceed materials were sufficiently stirred using a stirrer.
Double boiling was performed in a reactor suitable for the reaction temperature using water, and the mixture was stirred at a temperature corresponding to the experimental conditions through a temperature control unit for 30 minutes to 1 hour to maintain a uniform temperature.
The negative electrode and the positive electrode in the reactor were were installed such that they are in the form to face each other while maintaining a distance of 1 mm to 5 mm, and the facing electrodes are immersed in the solution. In particular, the electrodes were prepar in a structure not to contact with each other and a gap was maintained in a constant state.
Thereafter, the mixture was carefully stirred using a stirrer so that the stirring could be proceeded in a state where no impact was applied to the electrodes. In particular, a turbine-type stirring blade with a diameter of 3 cm was used, and the RPM was maintained at 300 RPM.
The negative electrode and the positive electrode were connected to each electrode immersed in the solution in the reactor using a power supply, and a constant current was supplied to flow.
Upon confirming that all of the reactants were converted into a product, the supply of electricity was stopped and the product was separated using a reduced pressure filter.
The preparation was performed in the same manner as in Example 1, but an azo compound was prepared as in Table 1 below.
Regarding the quality of the obtained azodicarbonamide (ADCA) described in Table 1 below, the meanings of the following indications are as follows.
: It can be used as a high-quality product due to uniform particle shape and particle size.
∘: Although the particle shape and particle size are uniform, it is difficult to be used as a high-quality product because it includes materials with some different particle sizes, and it can be used as a general product.
Δ: The particle shape and particle size are not uniform, and thus it can be used as a product only after separation.
X: The particle shape is poor and the particle size distribution is wide, and thus it cannot be used as a product.
In Table 1, the total mass of the solution containing MaXb, HDCA, and the solvent is based on 100 g, and the time is based on 25 g of HDCA.
Referring to Table 1, in Examples 1 to 4, in which the type of material for supplying chlorine (Cl2) (i.e., MaXb) was changed, it was confirmed that although HCl, NaCl, KCl, MgCl2, HBr, etc. are all possible, ADCA of the best quality was obtained in the case of HCl.
In Examples 5 to 23, the content of MaXb was changed, and it was confirmed that when the content was less than 1 wt %, ADCA was not produced, whereas when it exceeded 30 wt %, ADCA of low quality was obtained with a yield of 70% or less.
In Examples 24 and 25, the amount of current was changed to be lower than those of other examples, and it was confirmed that although the reaction time was slightly longer, the quality of the ADCA was excellent.
In Examples 26 and 27, the content of HDCA was changed to be lower or higher than those of other examples, and it was confirmed that the quality of ADCA was all excellent regardless of the change in the content of HDCA.
Examples 28 to 30 are results according to the number of reuse of the reaction mother liquor, i.e., a chlorine source and water, recovered in Example 1, and it was confirmed that the yield per cycle of ADCA was the same regardless of the number of reuse.
Comparative Example 1 is a result obtained using urea instead of HDCA, and it was confirmed that no reaction occurred at all.
An azo compound was prepared in the same manner as in Example 1, except in Table 2 below.
Regarding the quality of the ADCA obtained described in Table 2 below, the meanings of the following indications are as follows.
: a decomposition temperature of about 207±0.5° C. (expression of an appropriate decomposition temperature),
∘: a decomposition temperature of higher than about 207.5° C. to 209.5° C. or below (slightly higher than the appropriate decomposition temperature),
Δ: a decomposition temperature of higher than about 209.5° C. (a decrease of foaming ratio performance due to delayed decomposition), and
X: a decomposition temperature of lower than about 206.5° C. (a decreased quality of a foaming body due to premature foaming)
In Table 2, in Examples 31 to 35, in which the content of HBr (i.e., a Br2 precursor) was changed, it was confirmed that when the Br2 precursor was less than 0.05 wt %, the amount of electric power per 1 g of ADCA was increased, whereas when it exceeded 5 wt %, the yield was lowered while the amount of electric power per 1 g of ADCA was increased.
An azo compound was prepared in the same manner as in Example 1 except that the control temperature of the temperature control unit was changed as shown in Table 3 below.
Regarding the quality of the ADCA obtained described in Table 3 below, the meanings of the following indications are as follows.
: a decomposition temperature of about 207±0.5° C. (expression of an appropriate decomposition temperature),
∘: a decomposition temperature of higher than about 207.5° C. to 209.5° C. or below (slightly higher than the appropriate decomposition temperature),
Δ: a decomposition temperature of higher than about 209.5° C. (a decrease of foaming ratio performance due to delayed decomposition), and
X: a decomposition temperature of lower than about 206.5° C. (a decreased quality of a foaming body due to premature foaming)
In Table 3, in Examples 36 to 41, in which the control temperature of the temperature control unit was changed, it was confirmed that the amount of electric power per 1 g of ADCA significantly increased when the adjusted reaction temperature exceeded 80° C.
An azo compound was prepared in the same manner as in Example 1, but with changes as shown in Table 4 below.
Regarding the quality of the ADCA obtained described in Table 4 below, the meanings of the following indications are as follows.
: a decomposition temperature of about 207±0.5° C. (expression of an appropriate decomposition temperature),
∘: a decomposition temperature of higher than about 207.5° C. to 209.5° C. or below (slightly higher than the appropriate decomposition temperature),
Δ: a decomposition temperature of higher than about 209.5° C. (a decrease of foaming ratio performance due to delayed decomposition), and
X: a decomposition temperature of lower than about 206.5° C. (a decreased quality of a foaming body due to premature foaming)
In Table 4, when the value of Relational Equation (1) is less than 0.1, it was confirmed that the amount of electric power per lg of ADCA was significantly increased and the quality was deteriorated.
An azo compound was prepared in the same manner as in Example 1, except that chlorine gas was directly introduced without electrolysis.
In Table 5, in Comparative Example 2, chlorine gas was directly introduceed without performing an electrolysis reaction, and ADCA was obtained in a high yield of 94%, but it was confirmed that there were problems in that a large amount of chlorine source had to be continuously introduceed, and 627.8 g of HCl was produced per 1 kg of ADCA but the HCl could not be reused, thus requiring wastewater treatment, and in that the HCl had to be neutralized using a large amount of an alkali compound for the wastewater treatment.
As described above, according to the embodiments of the present invention, it is possible to implement a device for producing an azo compound, in which it is not necessary to continuously introduce a chlorine source, etc. through a recycling process because a predetermined halogen compound (MaXb) is used, it can significantly reduce the burden of treatment of wastewater and by-products, and realize a high conversion rate and a high yield. Additionally, even if the electrolysis method is used, it is unnecessary to use a separator, and it is possible to implement a device for producing an azo compound capable of reducing electric power consumption compared to the convenitonal technology. Accordingly, the manufacturing process and process management can be easier, manufacturing cost can be reduced, and productivity can be improved.
In the present specification, preferred embodiments of the present invention have been disclosed. Although specific terms are used, these are only used in a general sense to easily describe the technical contents of the present invention and help the understanding of the present invention, but it is not meant to limit the scope of the present invention. It will be apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented, in additional to the embodiments disclosed herein. For example, those of ordinary skill in the art would be able to understand that the method for producing an azo compound according to the embodiments described with reference to
3A: reaction solution introduction unit
3B: hydrazo compound introduction unit
6: discharge unit
7: dehydration unit
8: dehydration mother liquor storage tank
9: recycling unit
10: vessel
11: negative electrode
12: positive electrode
13: separator
14: negative electrode compartment
15: positive electrode compartment
16: stirrer
20, 25: reaction tanks
35
a,
35
b: connecting pipes
45: pump
46: reaction solution transfer pump
55: electrode chamber
60A, 65A: negative electrodes
60B, 65B: positive electrodes
70, 75: stirrers
85: gas treatment unit
17, 100: solutions
S10: first step
S20: second step
S30: third step
S40: fourth step
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2020-0104216 | Aug 2020 | KR | national |
This application is a Continuation of International Application No. PCT/KR2021/011046, filed on Aug. 19, 2021, which claims priority to Korean Patent Application No 10-2020-0104216, filed on Aug. 19, 2020. The aforementioned applications are incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/KR2021/011046 | Aug 2021 | US |
| Child | 18171366 | US |
