JP5927840B2 - Perchlorate production apparatus and production method - Google Patents

Description

  The present invention relates to a perchlorate production apparatus and production method.

Perchlorates include solid fuel rocket propellant oxidizer (ammonium perchlorate), lithium ion battery supporting electrolyte (lithium perchlorate), airbag igniter (potassium perchlorate), It is used for various purposes.
Here, as described in detail in Non-Patent Document 1, as a manufacturing method of perchlorate, industrially, a sodium chlorate aqueous solution synthesized by electrolytic oxidation of a sodium chloride aqueous solution is further electrolytically oxidized to obtain a perchlorate. After sodium chlorate is synthesized, it is manufactured through a predetermined treatment. Therefore, in the conventional techniques so far, as described in, for example, Patent Document 1 and Patent Document 2, a method for efficiently electrolytically synthesizing a sodium perchlorate (NaClO ₄ ) aqueous solution has been focused. Has been.

Japanese Patent Laid-Open No. 3-199387 JP 2007-197740 A

J. et al. C. Schumacher (ed.), Perchlorates, A.M. C. S. Monograph No. 146, Reinhold, New York, 1960

However, in producing perchlorates other than sodium perchlorate, it is not always necessary to go through sodium perchlorate. Accordingly, the inventors of the present application have devised a method for producing a perchlorate in which the production process is simplified without going through the production of sodium perchlorate. In this manufacturing method, an electrolytic cell in which the anode side on which the anode is provided and the cathode side on which the cathode is provided is partitioned by a cation exchange membrane, and a sodium chlorate aqueous solution is electrolytically oxidized on the anode side to produce a perchloric acid aqueous solution. Then, a predetermined alkaline aqueous solution is added to the perchloric acid aqueous solution generated by this electrolytic oxidation, and a perchlorate is synthesized by a neutralization reaction.
However, since this manufacturing method uses sodium chlorate as a raw material, there is a problem in procurement stability of the raw material.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a perchlorate production apparatus and a production method capable of enhancing the procurement stability of raw materials when producing perchloric acid.

  In order to solve the above-mentioned problems, the present invention provides an anode side on which an anode is provided and a cathode side on which a cathode is provided, which are partitioned by a cation exchange membrane. A perchlorate is synthesized by neutralization by adding a substance that shows alkalinity to an electrolytic cell that produces an aqueous chloric acid solution and an aqueous solution of perchloric acid produced by electrolytic oxidation in the electrolytic cell. And a pH meter for measuring the pH on the anode side of the electrolytic cell, and based on the measurement result of the pH meter, an aqueous sodium hydroxide solution is added to the anode side of the electrolytic cell, and the aqueous sodium chloride solution In the process of producing an aqueous solution containing chloric acid as a main component by electrolytic oxidation, a perchlorate production apparatus having a pH adjuster for adjusting the pH on the anode side during the electrolytic oxidation is employed. To.

  Further, in the present invention, an oxygen gas amount measuring device for measuring the amount of oxygen gas generated at the anode by electrolytic oxidation in the electrolytic cell, and a current amount measurement for measuring the current amount in electrolytic oxidation in the electrolytic cell. Hypochlorous acid and chlorous acid produced on the anode side with electrolytic oxidation in the electrolytic cell based on the measurement results of the apparatus, the oxygen gas amount measuring device and the current amount measuring device A configuration having a measuring device that measures the amount of acid produced is employed.

And in this invention, the said pH control apparatus employ | adopts the structure of adjusting the pH in the said anode side at the time of the said electrolytic oxidation based on the production amount of the said hypochlorous acid.
Specifically, the pH adjusting device according to the present invention employs a configuration in which the pH on the anode side during the electrolytic oxidation is adjusted to 5.0 or more based on the amount of hypochlorous acid produced.

In addition, in the present invention, the pH adjusting device adjusts the pH on the anode side during the electrolytic oxidation based on the amount of chlorous acid produced after adjustment based on the amount of hypochlorous acid produced. A configuration of adjusting is adopted.
Specifically, the pH adjusting device according to the present invention employs a configuration in which the pH on the anode side during the electrolytic oxidation is adjusted to 2.3 or more based on the amount of chlorous acid produced.

  Furthermore, in the present invention, the pH adjusting device switches between adjustment based on the amount of hypochlorous acid produced and adjustment based on the amount of chlorous acid produced based on the measurement result of the measuring device. The configuration is adopted.

  In the present invention, an electrolytic cell in which the anode side on which the anode is provided and the cathode side on which the cathode is provided is partitioned by a cation exchange membrane, and an aqueous sodium chloride solution is electrolytically oxidized on the anode side to A step of generating a chloric acid aqueous solution, a step of adding a substance exhibiting alkalinity to the aqueous solution of perchloric acid generated by electrolytic oxidation, and synthesizing a perchlorate by a neutralization reaction, Based on the step of measuring the pH on the anode side of the electrolytic cell and the measurement result of the pH, a sodium hydroxide aqueous solution is added to the anode side of the electrolytic cell, and the sodium chloride aqueous solution is electrolytically oxidized to mainly produce chloric acid. In the process of producing an aqueous solution as a component, a method for producing a perchlorate is adopted, which includes a step of adjusting the pH on the anode side during the electrolytic oxidation.

According to the present invention, by using sodium chloride, which is easier to obtain than sodium chlorate, as a raw material, the procurement stability of the raw material is increased, and perchlorate can be stably supplied.
The present invention also provides a sodium chloride aqueous solution by electrolytically oxidizing a sodium chloride aqueous solution on the anode side using an electrolytic cell in which an anode side provided with an anode and a cathode side provided with a cathode are partitioned by a cation exchange membrane. Sodium ions (Na ⁺ ) in the aqueous solution move from the anode side to the cathode side through the cation exchange membrane, while chloride ions (Cl ⁻ ) in the sodium chloride aqueous solution cannot pass through the cation exchange membrane. Chloric acid is generated through hypochlorous acid and chlorous acid by electrolytic oxidation on the anode side, staying on the anode side. Chlorine gas or chlorine dioxide gas is generated when the aqueous solution on the anode side becomes strongly acidic in the process of generating chloric acid, but the generation of these gases can be prevented by controlling the pH on the anode side. Can do.

  With electrolytic oxidation in the electrolytic cell, sodium ions move from the anode side to the cathode side through the cation exchange membrane, and the anode side gradually changes to strongly acidic. As a result, when the pH of the anode side aqueous solution is not controlled, the generated hypochlorous acid and chlorous acid are released out of the system as chlorine gas and chlorine dioxide gas. As a result, there is a concern that the yield of chloric acid may be reduced in the process of producing chloric acid. Therefore, the present invention measures the pH on the anode side using a pH meter, and adjusts the pH on the anode side by adding an alkaline sodium hydroxide aqueous solution on the basis of the measurement result. Prevent rate decline. If sodium hydroxide produced at the cathode by electrolytic oxidation is used to adjust the pH of the anode-side aqueous solution, it is even better because it is not necessary to prepare sodium hydroxide separately.

In the pH adjustment of the present invention, first, the pH on the anode side of the electrolytic cell is adjusted to 5.0 or more, thereby preventing generation of chlorine gas and increasing the yield of chlorous acid. This is because when the pH on the anode side of the electrolytic cell reaches an acidic value of less than 5.0, the presence state of hypochlorous acid changes and chlorine gas (Cl ₂ ) is generated and discharged out of the system. It is.
Next, the pH adjustment of the present invention adjusts the pH on the anode side of the electrolytic cell to 2.3 or higher, thereby preventing generation of chlorine dioxide gas and increasing the yield of chloric acid. This is because chlorous acid is discharged out of the system as chlorine dioxide gas (ClO ₂ ) when the pH on the anode side of the electrolytic cell reaches an acidic value of less than 2.3.

Further, according to the present invention, the pH adjustment on the anode side of the electrolytic cell is adjusted to 5 based on the amount of chlorous acid produced by the oxidation of hypochlorous acid on the anode side along with the electrolytic oxidation in the electrolytic cell. Switch from 0 or more to 2.3 or more. In order to increase the purity of perchlorate (other than sodium perchlorate), it is desirable that the sodium ion in the aqueous solution on the anode side after electrolytic oxidation is small, that is, the pH should be low. by. Therefore, when hypochlorous acid is electrolytically oxidized and chlorous acid is generated, chlorine dioxide gas is not generated if the pH on the anode side is 2.3 or more. Therefore, after the hypochlorous acid is electrolytically oxidized and chlorous acid is generated along with the electrolytic oxidation in the electrolytic cell, it is beneficial to adjust the pH on the anode side to 2.3 or more in a later step.
Usually, liquid ion chromatography is used as a method for measuring the amount of hypochlorous acid and chlorous acid produced. However, the analysis takes time and effort. On the other hand, in the present invention, by monitoring the amount of hypochlorous acid and chlorous acid generated based on the amount of oxygen gas generated at the anode by electrolytic oxidation in the electrolytic cell and the amount of current in this electrolytic oxidation. The pH adjustment of the anode side aqueous solution can be switched at an appropriate timing. As a result, it is possible to continuously perform the electrolysis process.

It is a flowchart which shows the manufacturing process of the ammonium perchlorate in embodiment of this invention. It is a schematic block diagram of the ammonium perchlorate manufacturing apparatus in embodiment of this invention. It is a block diagram of the primary electrolytic cell in embodiment of this invention. It is a figure which shows the relationship between the presence state of hypochlorous acid aqueous solution, and pH. It is a figure which shows the relationship between the presence state of chlorous acid aqueous solution, and pH. It is a block diagram of the secondary electrolytic cell in embodiment of this invention.

  Hereinafter, the manufacturing apparatus and manufacturing method of the perchlorate of embodiment of this invention are demonstrated with reference to drawings. Here, an example in which the present invention is applied to an ammonium perchlorate production apparatus and production method will be described.

FIG. 1 is a flow diagram showing a process for producing ammonium perchlorate in an embodiment of the present invention. As shown in the figure, the production process of ammonium perchlorate according to the present invention is roughly divided into four steps: a primary electrolysis step S1, a secondary electrolysis step S2, a reaction step S3, and a crystallization step S4.
The primary electrolysis step S1 is a step of electrolytically oxidizing a sodium chloride aqueous solution to generate an aqueous solution containing chloric acid as a main component. The next secondary electrolysis step S2 is a step of electrolytically oxidizing the aqueous solution containing chloric acid as a main component generated in the primary electrolysis step S1 to generate a perchloric acid aqueous solution. The next reaction step S3 is a step of adding ammonium aqueous solution to the perchloric acid aqueous solution generated in the secondary electrolysis step S2 to synthesize ammonium perchlorate by a neutralization reaction. The final crystallization step S4 is a step of crystallizing ammonium perchlorate by evaporating the aqueous solution after the neutralization reaction under vacuum and in a high temperature environment and cooling the concentrated aqueous solution.

Then, the ammonium perchlorate manufacturing apparatus which implements this manufacturing process is demonstrated.
FIG. 2 is a schematic configuration diagram of an ammonium perchlorate production apparatus (perchlorate production apparatus) A in the embodiment of the present invention. The symbols g, l, and s in the figure indicate a gas, liquid, and solid state, respectively. The ammonium perchlorate production apparatus A of the embodiment includes a primary electrolytic cell (electrolytic cell) 1 that performs a primary electrolysis step S1, a secondary electrolytic cell (electrolytic cell) 2 that performs a secondary electrolysis step S2, a reaction step S3, and And a reaction / evaporation tank 3 for performing the crystallization step S4.

FIG. 3 is a configuration diagram of the primary electrolytic cell 1 in the embodiment of the present invention.
The primary electrolytic cell 1 has a cation exchange membrane 6 provided so as to partition an anode side 4A where the anode 4 is provided and a cathode side 5A where the cathode 5 is provided. In the primary electrolytic cell 1, the anode side solution (anolyte) becomes strongly acidic and the cathode side solution (catholyte) becomes strongly alkaline by electrolytic oxidation described later. Therefore, it is desirable to use a main body of the primary electrolytic cell 1 having excellent chemical resistance, such as Teflon (DuPont, registered trademark), vinyl chloride, or glass. In addition, it is desirable to use a pipe joint having excellent chemical resistance, for example, Teflon (DuPont Co., Ltd., registered trademark).

  The cation exchange membrane 6 constitutes a zero-gap electrolytic cell sandwiched between the anode 4 and the cathode 5 in the primary electrolytic cell 1 without a gap. This cation exchange membrane 6 is a membrane having the characteristics that it can pass cations but not anions. In this embodiment, Nafion 424 (Nafion, DuPont, registered trademark) is used as the cation exchange membrane 6. ) Is used. As the cation exchange membrane, Aciplex (Asahi Kasei Co., Ltd., registered trademark) or Flemion (Asahi Glass Co., Ltd., registered trademark) widely used in caustic soda production may be used.

The anode 4 is made of an expanded metal coated with a catalyst in order to promote the electrolytic synthesis reaction of chlorate ions on the anode side 4A. The anode 4 of this embodiment is an electrode in which the surface of a titanium expanded metal as a substrate is coated with a catalyst layer made of iridium oxide and platinum by a firing method, which has an effect of suppressing the generation of oxygen gas, or by a firing method. An electrode coated with a catalyst layer made of iridium oxide and ruthenium oxide, an electrode coated with a catalyst layer made of iridium oxide, ruthenium oxide and platinum by a firing method, or a catalyst layer made of tantalum oxide and platinum by a firing method It is comprised from the electrode which did.
On the other hand, the cathode 5 paired with the anode 4 is composed of an electrode in which the surface of a titanium expanded metal as a base is covered with a platinum catalyst layer by electrolytic plating, or an electrode made of nickel expanded metal.

  The anode side 4A is provided with an anolyte tank 4B for storing the anolyte (hereinafter, the anode side 4A of the electrolytic cell 1 is referred to as an anode side electrolytic cell 2A). The liquid level of the anolyte in the anolyte tank 4B is higher than the liquid level in the anode side electrolytic cell 2A. The anolyte tank 4B and the anode side electrolytic cell 2A are connected by a pipe 27a and a pipe 27b. The pipe 27a connects the bottom of the anode electrolytic cell 2A and the bottom of the anolyte tank 4B, and the pipe 27b connects the top of the anode electrolytic tank 2A and the side of the anolyte tank 4B. Is. An ultrasonic transducer 4B1 is provided at the bottom of the anolyte tank 4B to keep the concentration of the anolyte uniform. As a method for keeping the concentration of the anolyte uniform, a stirrer may be provided inside the anolyte tank 4B.

  On the other hand, the cathode side 5A is provided with a catholyte tank 5B for storing catholyte (hereinafter, the cathode side 5A of the electrolytic cell 1 is referred to as a cathode side electrolytic cell 2B). The liquid level of the catholyte in the catholyte tank 5B is higher than the liquid level in the cathode side electrolytic cell 2B. The catholyte tank 5B and the cathode side electrolytic cell 2B are connected by a pipe 28a and a pipe 28b. The piping 28a connects the bottom of the cathode side electrolytic cell 2B and the bottom of the catholyte tank 5B, and the piping 28b connects the top of the cathode side electrolytic cell 2B and the side of the catholyte tank 5B. Is.

  An anolyte introduction pipe 21 is connected to the top of the anolyte tank 4B, and an aqueous sodium chloride solution is introduced through the anolyte introduction pipe 21 to connect the anode side 4A (the anode side electrolytic cell 2A and the anolyte tank 4B). Satisfy). On the other hand, a catholyte introduction pipe 22 is connected to the top of the catholyte tank 5B, and pure water is introduced through the catholyte introduction pipe 22, and the cathode side 5A (cathode side electrolytic cell 2B, catholyte tank 5B). Meet). When a voltage is applied to both the anode 4 and the cathode 5 immersed in each solution inside the primary electrolytic cell 1, the following reaction proceeds.

On the anode side 4A, the aqueous sodium chloride solution is electrolytically oxidized, and the reactions shown in the following reaction formulas (1) and (2) occur.
2Cl ⁻ → Cl ₂ + 2e ⁻ ... (1)
2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ ... (2)
The chlorine gas generated here causes the equilibrium reaction shown in the following reaction formulas (3) and (4). The form of this equilibrium reaction changes depending on the pH of the aqueous solution.
Cl ₂ + H ₂ O⇔H ⁺ + Cl ⁻ + HClO (3)
HClO⇔H ⁺ + ClO ⁻ (4)

When the hypochlorous acid generated by this reaction is electrolytically oxidized, chlorous acid is generated by the reactions shown in the following reaction formulas (5) and (6).
ClO ⁻ + H ₂ O → ClO ₂ ⁻ + 2H ⁺ + 2e ⁻ ... (5)
HClO + H ₂ O → HClO ₂ + 2H ⁺ + 2e ⁻ ... (6)
When the produced chlorous acid is further electrolytically oxidized, chloric acid is produced by the reactions shown in the following reaction formulas (7) and (8).
ClO ₂ ⁻ + H ₂ O → ClO ₃ ⁻ + 2H ⁺ + 2e ⁻ ... (7)
HClO ₂ + H ₂ O → HClO ₃ + 2H ⁺ + 2e ⁻ (8)

As shown in the reaction formulas (1) to (8), in the primary electrolysis process, oxygen gas is generated as chloric acid and by-products. Therefore, from the viewpoint of power consumption suppression, it is desirable to suppress the generation of oxygen gas by using the coated titanium expanded metal containing indium oxide as a catalyst as the anode 4.
Here, sodium ions contained in the liquid on the anode side 4A move from the anode side 4A to the cathode side 5A through the cation exchange membrane 6 due to the potential difference between the two electrodes. On the other hand, hypochlorite ions cannot pass through the cation exchange membrane 6 and become chlorate ions via chlorite ions by the oxidation reaction at the three interfaces composed of the aqueous solution-anode 4-cation exchange membrane 6. .

The oxygen gas (bubbles) generated in the anode side electrolytic cell 2A is guided to the anolyte tank 4B through the pipe 27b. An oxygen gas pipe 23 is provided at the top of the anolyte tank 4B, and oxygen gas is sequentially exhausted to the outside through the oxygen gas pipe 23.
In addition, since the anolyte is sequentially introduced from the anolyte tank 4B from the bottom of the anode side electrolytic cell 2A through the pipe 27a due to the difference in liquid level (water pressure difference), the electrolytically oxidized anolyte is It is extruded from the electrolytic cell 2A to the anolyte tank 4B side through the pipe 27b. Accordingly, since the anolyte circulates between the anode side electrolytic cell 2A and the anolyte tank 4B regardless of the driving mechanism such as a pump, more anolyte is electrolytically oxidized in the anode side electrolytic cell 2A.

On the cathode side 5A, the reactions shown in the following reaction formulas (9) and (10) occur, and hydrogen gas and sodium hydroxide are generated.
2H ⁺ + 2e ⁻ → H ₂ (9)
2Na ⁺ + 2H ₂ O + 2e ⁻ → 2NaOH + H ₂ (10)
The hydrogen gas (bubbles) generated in the cathode side electrolytic cell 2B is guided to the catholyte tank 5B through the pipe 28b. A hydrogen gas pipe 24 is provided at the top of the catholyte tank 5B, and the hydrogen gas is sequentially exhausted to the outside through the hydrogen gas pipe 24. Similarly to the circulation of the anolyte at the anode side 4A, the circulation of the catholyte can be obtained at the cathode side 5A.

  Due to the electrolytic oxidation, sodium ions contained in the liquid on the anode side 4A move from the anode side 4A to the cathode side 5A through the cation exchange membrane 6 due to the potential difference between the two electrodes. This contributes to the change of the anolyte to strongly acidic. When the anolyte becomes strongly acidic with electrolytic oxidation, chlorine gas and chlorine dioxide gas are generated. As a result, a decrease in the yield of chloric acid occurs. Therefore, in the present embodiment, a pH adjustment system 10 that adjusts the pH on the anode side 4A during electrolytic oxidation for the purpose of preventing generation of chlorine gas and chlorine dioxide gas is provided.

  The pH adjusting system 10 is for adding a pH adjusting agent to the anolyte from a pH adjusting agent introduction pipe 11 connected to the top of the anolyte tank 4B, and is provided on the side of the anolyte tank 4B. A pH meter 12 for measuring the pH of the gas, a flow meter (oxygen gas amount measuring device) 13 provided in the oxygen gas pipe 23 for measuring the amount of oxygen gas generated at the anode 4 by electrolytic oxidation, and used for electrolytic oxidation An ammeter (current amount measuring device) 14 for measuring the amount of current and a pH adjusting device for adding a sodium hydroxide aqueous solution as a pH adjusting agent from the pH adjusting agent introduction pipe 11 to the anolyte tank 4B based on the measurement results. 15.

  The pH adjuster 15 is electrically connected to the pH meter 12, the flow meter 13, and the ammeter 14, and data of measurement results are input from each, and the amount of pH adjuster added based on the data. It has a computer system (measuring device) to control. Specifically, the pH adjusting device 15 includes a hypochlorous acid aqueous solution pH adjusting program for the purpose of preventing the generation of chlorine gas, and a chlorous acid aqueous solution pH adjusting program for the purpose of preventing the generation of chlorine dioxide gas. And a program for switching these adjustment programs based on the amount of chlorous acid produced on the anode side 4A in the memory, and adjusting the pH of the anode side 4A of the primary electrolytic cell 1 based on these programs It is the composition which performs.

First, with reference to FIG. 4, the pH adjustment of the hypochlorous acid aqueous solution for the purpose of preventing the generation of chlorine gas will be described.
FIG. 4 is a diagram showing the relationship between the presence state of hypochlorous acid aqueous solution and pH. In FIG. 4, the horizontal axis represents pH, and the vertical axis represents the abundance ratio.
As shown in FIG. 4, when the pH of the anolyte containing hypochlorous acid as a main component becomes an acid value of less than 5 with electrolytic oxidation in the primary electrolytic cell 1, hypochlorous acid is converted to chlorine gas (Cl ₂ ). As a result, the gas is discharged to the outside through the oxygen gas pipe 23. As a result, the yield of chloric acid, which is the final product of the primary electrolysis process, decreases.
Therefore, in the pH adjustment program for the hypochlorous acid aqueous solution for the purpose of preventing the generation of chlorine gas, based on the data shown in FIG. Control to add an aqueous sodium hydroxide solution to the liquid is performed.

Next, with reference to FIG. 5, the pH adjustment of the aqueous chlorous acid solution for the purpose of preventing the generation of chlorine dioxide gas will be described.
FIG. 5 is a diagram showing the relationship between the presence state of chlorous acid aqueous solution and pH (Source: Food Safety Commission, Additive Evaluation, Chlorous acid water, June 2008). In FIG. 5, the horizontal axis represents pH, and the vertical axis represents the abundance ratio.
As shown in FIG. 5, when the pH of the anolyte containing chlorous acid as a main component becomes less than 2.3 with electrolytic oxidation in the primary electrolytic cell 1, the presence state of chlorous acid changes. It will exist as chlorine dioxide gas (ClO ₂ ). As a result, similarly to the generation of the chlorine gas, the chlorine dioxide gas is discharged to the outside through the oxygen gas pipe 23, so that the yield of chloric acid, which is the final product of the primary electrolysis process, is reduced.
Therefore, in the pH adjustment program of the aqueous chlorous acid solution for the purpose of preventing the generation of chlorine dioxide gas, based on the data shown in FIG. The sodium hydroxide aqueous solution is added to the anolyte.

  In producing ammonium perchlorate, it is desirable that the amount of sodium ions is small in order to increase its purity. Here, when chlorous acid is generated by electrolytic oxidation of hypochlorous acid, chlorine dioxide gas is not generated if the pH of the anode side 4A is 2.3 or more. Therefore, after all the hypochlorous acid has been converted to chlorous acid along with the electrolytic oxidation in the primary electrolytic cell 1, the pH control value of the anode side 4A can be switched from 5.0 or more to 2.3 or more. Useful in later steps. Therefore, the pH adjuster 15 of the present embodiment estimates the amount of hypochlorous acid and chlorous acid generated based on the measurement results of the flow meter 13 and the ammeter 14, and sets the pH control value of the anode side 4A. A program for switching from 5.0 or higher to 2.3 or higher is provided. The pH adjuster 15 estimates the amount of hypochlorous acid and chlorous acid generated based on the arithmetic expression described below.

First, the number of electrons required for producing hypochlorous acid, chlorous acid, and chloric acid by electrolytic oxidation of an aqueous sodium chloride solution will be described. As shown in Reaction Formula (1) to Reaction Formula (8), in order to produce 1 mol of hypochlorous acid by electrolytically oxidizing a sodium chloride aqueous solution in which 1 mol of sodium chloride is dissolved in water, Necessary. Furthermore, 2 mol of electrons are required to produce 1 mol of chlorous acid from hypochlorous acid. Therefore, 4 mol of electrons are required to produce 1 mol of chlorous acid from the sodium chloride aqueous solution that is the starting material. And in order to produce | generate 1 mol of chloric acids from the sodium chloride aqueous solution which is a starting material, 6 mol electrons are needed.
In reality, in addition to the reactions shown in the reaction formulas (1) to (8), when platinum is used as the catalyst of the anode 4, the platinum is converted into chloroplatinate ions (PtCl ₄ ²⁻ ). A reaction that elutes in the aqueous solution occurs. Further, when electrolysis is performed at a high current density of 1.0 A / cm ² or more, ozone (O ₃ ) can be generated. However, the amount of products generated by these reactions is sufficiently smaller than the products generated by the reactions shown in the reaction formulas (1) to (8). Therefore, these reactions are ignored here.

In estimating the amount of hypochlorous acid, chlorous acid, and chloric acid generated from the amount of current and the amount of oxygen gas generated, the amount of oxygen gas generated when current I (A) is applied for t hours (in seconds). Is P _O2 (unit: liter (L)). Here, assuming a standard state (0 ° C., 1 atm), P _{2 O 2} /22.4 (mol) of oxygen gas was generated and moved from the anode 4 to the cathode 5 along with the generation of oxygen gas. The number of electrons e _O2 (mol) is four times P _O2 /22.4. On the other hand, the _total number of electrons e _total (mol) transferred from the anode 4 to the cathode 5 can be expressed by the following formula (a) using the Faraday constant F (= 9.6485 × 10 ⁴ C / mol). it can.

  Therefore, the number of electrons transferred from the anode 4 to the cathode 5 with the generation of hypochlorous acid can be expressed by the following mathematical formula (b).

In conclusion, the amount of hypochlorous acid produced P _HClO can be estimated by the following mathematical formula (c) using the current amount I · t (C) and the oxygen gas generation amount P _O2 (L). Here, κ _HClO is the formula amount of HClO and is 52.46 (g / mol).

Similarly, the generation amount P _HClO2 of chlorous acid can be estimated by the following mathematical formula (d) using the current amount I · t (C) and the oxygen gas generation amount P _O2 (L). Here, kappa _HClO2 is formula weight of HClO _2, is 68.46 (g / mol).

Furthermore, the chloric acid production amount P _HClO3 can be estimated by the following formula (e) using the current amount I · t (C) and the oxygen gas generation amount P _O2 (L). Here, kappa _HClO3 is formula weight of HClO _3, is 84.46 (g / mol).

  Accordingly, the pH adjusting device 15 first adjusts the pH of the anolyte on the anode side 4A to 5 or more for the purpose of preventing the generation of chlorine gas at the time of electrolytic oxidation in the primary electrolytic cell 1. Then, the pH adjusting device 15 sets the pH of the anolyte on the anode side 4A to 2.3 or more at a stage where it can be estimated that hypochlorous acid has been converted to chlorous acid based on the arithmetic expression shown in Formula (d). Adjust to. In this way, the pH adjuster 15 prevents generation of chlorine gas and generation of chlorine dioxide gas, increases the yield, and moves sodium ions to the cathode side 5A as much as possible.

  The anolyte mainly composed of chloric acid produced by electrolytic oxidation in the primary electrolytic cell 1 is subjected to secondary electrolysis from the anolyte tank 4B through the anolyte transport pipe 25 in which the valve 25A is opened from the closed state. It is transported to the tank 2. On the other hand, the catholyte is transported to the outside from the catholyte tank 5B through the catholyte transport pipe 26 in which the valve 26A is opened from the closed state.

FIG. 6 is a configuration diagram of the secondary electrolytic cell 2 in the embodiment of the present invention.
The secondary electrolytic cell 2 generates perchloric acid by electrolytically oxidizing the anolyte mainly composed of chloric acid generated in the primary electrolytic cell 1.
In addition, in order to avoid duplication description, the structure of the secondary electrolytic cell 2 demonstrated below attaches | subjects the same code | symbol about the same or equivalent component as the above-mentioned primary electrolytic cell 1, and the description is simplified or abbreviate | omitted.

In the secondary electrolytic cell 2, the cation exchange membrane 6 constitutes a zero-gap electrolytic cell sandwiched between the anode 4 'and the cathode 5' without a gap.
The anode 4 'is made of an expanded metal coated with a catalyst in order to promote the electrolytic synthesis reaction of perchlorate ions on the anode side 4A. The anode 4 'is composed of an electrode in which the surface of a titanium expanded metal as a base is coated with a platinum catalyst layer by electrolytic plating.
On the other hand, the cathode 5 'paired with the anode 4' is made of expanded metal coated with a catalyst. The cathode 5 'is composed of an electrode in which the surface of a titanium expanded metal as a base is covered with a platinum catalyst layer by electrolytic plating, an electrode made of SUS316 expanded metal, or an electrode made of nickel expanded metal.

  An anolyte transport pipe 25 of the primary electrolyzer 1 is connected to the top of the anolyte tank 4B of the secondary electrolyzer 2 as an anolyte introduction pipe, and the anolyte after the primary electrolysis step is anolyte transport pipe 25. To fill the anode side 4A (including the anode side electrolytic cell 2A and the anolyte tank 4B). On the other hand, a catholyte introduction pipe 22 is connected to the top of the catholyte tank 5B, and pure water is introduced through the catholyte introduction pipe 22, and the cathode side 5A (cathode side electrolytic cell 2B, catholyte tank 5B). Meet). When a voltage is applied to both the anode 4 'and the cathode 5' immersed in each solution inside the secondary electrolytic cell 2, the following reaction proceeds.

On the anode side 4A, the anolyte that has undergone the primary electrolysis step is electrolytically oxidized, and oxygen gas is generated as perchloric acid and by-products as shown in the following reaction formulas (11) and (12). . In addition, although it is a trace amount, as shown in the following reaction formula (13), ozone gas is also generated as a by-product.
HClO ₃ + H ₂ O → HClO ₄ + 2H ⁺ + 2e ⁻ ... (11)
2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ ... (12)
3H ₂ O → O ₃ + 6H ⁺ + 6e ⁻ ... (13)
Here, sodium ions contained in the anolyte after passing through the primary electrolysis step on the anode side 4A pass through the cation exchange membrane 6 due to the potential difference between the two electrodes and move from the anode side 4A to the cathode side 5A. On the other hand, chlorate ions cannot pass through the cation exchange membrane 6 and become perchloric acid by the oxidation reaction shown in the reaction formula (11) at the three interfaces constituted by the aqueous solution-anode 4'-cation exchange membrane 6.

On the cathode side 5A, the reactions shown in the following reaction formulas (14) and (15) occur, and hydrogen gas and sodium hydroxide are generated.
2H ⁺ + 2e ⁻ → H ₂ (14)
2Na ⁺ + 2H ₂ O + 2e ⁻ → 2NaOH + H ₂ (15)
The anolyte in which a sufficient amount of perchloric acid has been generated is transported from the anolyte tank 4B to the reaction / evaporation tank 3 via the anolyte transport pipe 25 'in which the valve 25A is opened from the closed state. On the other hand, the catholyte is transported to the outside from the catholyte tank 5B through the catholyte transport pipe 26 in which the valve 26A is opened from the closed state.

In the reaction / evaporation tank 3, a step of synthesizing ammonium perchlorate by adding an aqueous ammonia solution to the anolyte after electrolytic oxidation, and a step of evaporating the synthesized anolyte under vacuum at high temperature to produce ammonium perchlorate And crystallization step. Here, ammonia gas may be bubbled instead of the aqueous ammonia solution.
An ammonia supply pipe 31 is connected to the reaction / evaporation tank 3 to supply an aqueous ammonia solution into the anolyte after electrolytic oxidation. When an aqueous ammonia solution is added to the anolyte after electrolytic oxidation, a neutralization reaction shown in the following reaction formula (16) occurs, and water is synthesized as an ammonium perchlorate as a by-product and a by-product.
HClO ₄ + NH ₄ OH → NH ₄ ClO ₄ + H ₂ O ... (16)

  Next, in the reaction / evaporation tank 3, the synthesized anolyte is evaporated under vacuum and in a high temperature environment, and the concentrated aqueous solution is cooled to take out ammonium perchlorate as crystals. As shown in the reaction formula (16), since the by-product obtained together with ammonium perchlorate is water, high-purity ammonium perchlorate crystals can be easily formed compared to the method described in Non-Patent Document 1. Is obtained.

  As described above, according to the present embodiment, the anode side 4A provided with the anode 4 and the cathode side 5A provided with the cathode 5 are partitioned by the cation exchange membrane 6, and the sodium chloride aqueous solution is electrolyzed on the anode side 4A. A primary electrolytic cell 1 that oxidizes to produce an aqueous solution containing chloric acid as a main component, and an anode side 4A provided with an anode 4 'and a cathode side 5A provided with a cathode 5' are partitioned by a cation exchange membrane 6. A secondary electrolytic cell 2 for producing an aqueous solution of perchloric acid by electrolytically oxidizing an aqueous solution mainly composed of chloric acid produced by electrolytic oxidation in the primary electrolytic cell 1 on the anode side 4A, and a secondary electrolytic cell 2 An ammonium perchlorate production apparatus A having a reaction / evaporation tank 3 in which ammonia is added to a perchloric acid aqueous solution produced by electrolytic oxidation at, and ammonium perchlorate is synthesized by a neutralization reaction. By salt By using sodium chloride, which is less expensive than sodium silicate and easily available, as a raw material, the procurement stability of the raw material is increased, and ammonium perchlorate can be stably produced.

  Further, the anode side 4 </ b> A changes to strongly acidic with electrolytic oxidation in the primary electrolytic cell 1. As a result, the chlorine gas generated by the change in the presence state of hypochlorous acid and the chlorine dioxide gas generated by the change in the presence state of chlorous acid are discharged out of the system of the primary electrolytic cell 1, and thus are intermediate products. There is concern about a decrease in the yield of chloric acid. Therefore, in this embodiment, the pH of the anode side 4A is measured using the pH meter 12, and based on the measurement result, an alkaline sodium hydroxide aqueous solution is added to adjust the pH of the anode side 4A. Prevents a decrease in yield. If the sodium hydroxide aqueous solution added here uses a by-product generated on the cathode side 5A by this electrolytic oxidation, it is not necessary to procure sodium hydroxide as a raw material.

In the pH adjustment of the present embodiment, first, pH adjustment for the purpose of preventing generation of chlorine gas is performed in the primary electrolysis process. When the pH of the anolyte mainly composed of hypochlorous acid in the primary electrolytic cell 1 is less than 5, chlorine gas is generated and discharged out of the system. Therefore, by adjusting the pH to 5 or more, chlorine gas Generation of chloric acid can be prevented.
Next, the pH adjustment of the present embodiment is performed for the purpose of preventing the generation of chlorine dioxide gas in the primary electrolysis step. When the pH of the anolyte containing chlorous acid as the main component in the primary electrolytic cell 1 is less than 2.3, the presence state of chlorous acid changes and is discharged out of the system as chlorine dioxide gas. By adjusting to 3 or more, generation of chlorine dioxide gas can be prevented and the yield of chloric acid can be increased.

In the present embodiment, the pH adjustment of the hypochlorous acid aqueous solution for the purpose of preventing the generation of chlorine gas and the pH adjustment of the aqueous chlorous acid solution for the purpose of preventing the generation of the chlorine dioxide gas are as follows. Switch based on the amount of chlorous acid and chlorous acid produced. In producing ammonium perchlorate, it is desirable that the amount of sodium ions is small in order to increase its purity. Therefore, when chlorous acid is generated by electrolytic oxidation of hypochlorous acid, chlorine dioxide gas is not generated if the pH of the anode side 4A is 2.3 or more. Therefore, after a predetermined amount of chlorous acid is generated along with the electrolytic oxidation in the primary electrolytic cell 1, it is beneficial to adjust the pH of the anode side 4A to 2.3 or more in a later step.
Usually, liquid ion chromatography is used to measure the amount of hypochlorous acid and chlorous acid produced. However, since the analysis takes time and effort, in this embodiment, based on the amount of oxygen gas generated at the anode 4 by electrolytic oxidation in the primary electrolytic cell 1 and the amount of current in this electrolytic oxidation, By monitoring the amount of hypochlorous acid, chlorous acid, and chloric acid produced, the pH adjustment of the anode side 4A can be switched at an appropriate timing.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, the present invention is not limited to the application to the above-described ammonium perchlorate production apparatus, but an alkali metal perchlorate production apparatus such as lithium perchlorate or potassium perchlorate, and perchloric acid. The present invention can also be applied to an apparatus for producing alkaline earth metal perchlorates such as calcium and an apparatus for producing silver perchlorate.

  In addition, for example, the present invention generates a perchloric acid aqueous solution in one electrolytic cell as well as a form in which the perchloric acid aqueous solution is generated using the two electrolytic cells of the primary electrolytic cell and the secondary electrolytic cell described above. The present invention can also be applied to a form or a form in which a perchloric acid aqueous solution is generated in three or more electrolytic cells. As for the electrolytic cell, not only the zero gap type, but also an electrolytic cell in which a cation exchange membrane is installed with a space between the anode and the cathode may be used.

  A ... Ammonium perchlorate production device (perchlorate production device), S1 ... Primary electrolysis step, ..., S2 ... Secondary electrolysis step, S3 ... Reaction step (synthesis step), S4 ... Crystalling step, 1 ... Primary electrolytic cell (electrolytic cell), 2 ... Secondary electrolytic cell (electrolytic cell), 3 ... Reaction / evaporation tank, 4 ... Anode, 4 '... Anode, 4A ... Anode side, 5 ... Cathode, 5' ... Cathode, 5A ... Cathode side, 6 ... Cation exchange membrane, 10 ... pH control system, 11 ... pH adjuster introduction tube, 12 ... pH meter, 13 ... Flow meter (oxygen gas amount measuring device), 14 ... Ammeter (current amount measurement) Device), 15 ... pH adjusting device

Claims (9)

An electrolytic cell in which an anode side provided with an anode and a cathode side provided with a cathode are partitioned by a cation exchange membrane, and an aqueous sodium chloride solution is electrolytically oxidized on the anode side to generate a perchloric acid aqueous solution;
A synthesis tank for synthesizing perchlorate by a neutralization reaction by adding a substance that exhibits alkalinity to the aqueous solution of perchloric acid generated by electrolytic oxidation in the electrolytic tank;
A pH meter for measuring the pH on the anode side of the electrolytic cell;
Based on the measurement result of the pH meter, in the process of adding an aqueous sodium hydroxide solution to the anode side of the electrolytic cell and electrolytically oxidizing the aqueous sodium chloride solution to produce an aqueous solution containing chloric acid as a main component, the electrolysis A pH adjuster for adjusting the pH on the anode side during oxidation;
An oxygen gas amount measuring device for measuring the amount of oxygen gas generated at the anode by electrolytic oxidation in the electrolytic cell;
A current amount measuring device for measuring a current amount in electrolytic oxidation in the electrolytic cell;
Generation of hypochlorous acid and chlorous acid generated on the anode side with electrolytic oxidation in the electrolytic cell based on the measurement result of the oxygen gas amount measuring device and the measurement result of the current amount measuring device A measuring device for measuring the quantity;
An apparatus for producing perchlorate, comprising: A primary electrolytic cell in which an anode side on which an anode is provided and a cathode side on which a cathode is provided are partitioned by a cation exchange membrane, and an aqueous solution containing chloric acid as a main component is generated by electrolytically oxidizing a sodium chloride aqueous solution on the anode side When,
The anode side on which the anode is provided and the cathode side on which the cathode is provided are partitioned by a cation exchange membrane, and an aqueous solution mainly composed of chloric acid generated by electrolytic oxidation in the primary electrolytic cell is electrolytically oxidized on the anode side. One or more secondary electrolyzers for producing a perchloric acid aqueous solution,
A synthesis tank for synthesizing perchlorate by a neutralization reaction by adding a substance showing alkalinity when converted to an aqueous solution of perchloric acid generated by electrolytic oxidation in the secondary electrolytic tank;
A pH meter for measuring pH on the anode side of the primary electrolytic cell;
Based on the measurement result of the pH meter, in the process of adding a sodium hydroxide aqueous solution to the anode side of the primary electrolytic cell, and electrolytically oxidizing the sodium chloride aqueous solution to produce an aqueous solution containing chloric acid as a main component, A pH adjusting device for adjusting the pH on the anode side during electrolytic oxidation;
An oxygen gas amount measuring device for measuring the amount of oxygen gas generated at the anode by electrolytic oxidation in the primary electrolytic cell;
A current amount measuring device for measuring a current amount in electrolytic oxidation in the primary electrolytic cell;
Based on the measurement result of the oxygen gas amount measuring device and the measurement result of the current amount measuring device, hypochlorous acid and chlorous acid generated on the anode side along with the electrolytic oxidation in the primary electrolytic cell. A measuring device for measuring the generation amount;
An apparatus for producing perchlorate, comprising: The perchlorate production according to claim 1 or 2 , wherein the pH adjuster adjusts the pH on the anode side during the electrolytic oxidation based on the amount of hypochlorous acid produced. apparatus. The perchloric acid according to claim 3 , wherein the pH adjuster adjusts the pH on the anode side during the electrolytic oxidation to 5.0 or more based on the amount of hypochlorous acid produced. Salt production equipment. Wherein the pH adjusting apparatus, wherein after adjustment based on the amount of hypochlorous acid, based on the generation amount of the chlorite, and adjusting the pH in the anode side during the electrolytic oxidation Item 5. A perchlorate production apparatus according to Item 4 . 6. The perchlorate according to claim 5 , wherein the pH adjuster adjusts the pH on the anode side during the electrolytic oxidation to 2.3 or more based on the amount of chlorous acid produced. Manufacturing equipment. The pH adjusting device, the claims based on the measurement result of the measuring device, and performs switching between the adjustment based on the amount of regulation between the chlorite based upon the amount of the hypochlorous acid The manufacturing apparatus of the perchlorate as described in any one of 1-6 . A step of producing a perchloric acid aqueous solution by electrolytically oxidizing a sodium chloride aqueous solution on the anode side using an electrolytic cell in which an anode side provided with an anode and a cathode side provided with a cathode are partitioned by a cation exchange membrane When,
Adding a substance that shows alkalinity to the aqueous solution of perchloric acid generated by the electrolytic oxidation, and synthesizing perchlorate by a neutralization reaction;
Measuring the pH on the anode side of the electrolytic cell;
Based on the measurement result of the pH, in the process of adding an aqueous sodium hydroxide solution to the anode side of the electrolytic cell and electrolytically oxidizing the aqueous sodium chloride solution to produce an aqueous solution containing chloric acid as a main component, the electrolytic oxidation Adjusting the pH on the anode side at the time,
Measuring the amount of oxygen gas generated at the anode by electrolytic oxidation in the electrolytic cell;
Measuring the amount of current in electrolytic oxidation in the electrolytic cell;
Measuring the amount of hypochlorous acid and chlorous acid produced on the anode side along with the electrolytic oxidation in the electrolytic cell based on the measured amount of oxygen gas and the amount of current; ,
A method for producing perchlorate, comprising: Using a primary electrolytic cell in which the anode side on which the anode is provided and the cathode side on which the cathode is provided are partitioned by a cation exchange membrane, the sodium chloride aqueous solution is electrolytically oxidized on the anode side, and chloric acid is the main component. A primary electrolysis step for producing an aqueous solution;
Produced by electrolytic oxidation in the primary electrolysis step on the anode side using one or a plurality of secondary electrolytic cells in which the anode side on which the anode is provided and the cathode side on which the cathode is provided are partitioned by a cation exchange membrane A secondary electrolysis process in which an aqueous solution containing chloric acid as a main component is electrolytically oxidized to produce a perchloric acid aqueous solution;
Adding a substance that shows alkalinity to the aqueous solution of perchloric acid produced by electrolytic oxidation in the secondary electrolysis step, and synthesizing perchlorate by a neutralization reaction;
Measuring the pH on the anode side of the primary electrolytic cell;
Based on the measurement result of the pH, in the process of adding an aqueous sodium hydroxide solution to the anode side of the primary electrolytic cell and electrolytically oxidizing the sodium chloride aqueous solution to produce an aqueous solution containing chloric acid as a main component, the electrolysis Adjusting the pH on the anode side during oxidation;
Measuring the amount of oxygen gas generated at the anode by electrolytic oxidation in the primary electrolytic cell;
Measuring the amount of current in electrolytic oxidation in the primary electrolytic cell;
A step of measuring the amount of hypochlorous acid and chlorous acid produced on the anode side along with the electrolytic oxidation in the primary electrolytic cell based on the measured amount of the oxygen gas and the amount of current. When,
A method for producing perchlorate, comprising:

Images