JPH10125345A - Manufacture of vanadium electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel method for easily manufacturing a high- concentration solution of vanadium for a redox battery at low cost, with a low-cost vanadium oxide as the raw material. SOLUTION: This method includes a process for reducing a vanadium oxide (composed chiefly of V2 O5 or V6 O13 ), which is the raw material to a vanadium oxide composed chiefly of V2 O3 by heating the same material in a reducing atmosphere and a process for obtaining a solution of tetravalent vanadium sulfate (VOSO4 ), by dispersing equal moles of V2 O5 and the V2 O3 in the obtained vanadium oxide into water and thereafter dissolving them in sulfuric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-concentration vanadium electrolyte used for a redox battery.

[0002]

2. Description of the Related Art Recently, as the problem of environmental pollution has become more serious, the use of relatively clean electric energy among various types of energy has increased. This electrical energy
Because of high versatility and no environmental pollution at the time of consumption, demand is expected to increase further in the future.

[0003] Various secondary batteries have been researched and developed as a method of storing electric energy. Among them, a redox battery, which has a good operability and a large capacity, has attracted attention. In this redox battery, a liquid positive / negative battery active material is put into a liquid permeable electrolytic cell and charged / discharged by an oxidation / reduction reaction, and has a longer life than a conventional secondary battery. There are advantages such as high reliability and safety.

[0004]

Among the above redox batteries, a redox battery using a vanadium ion pair dissolved in a sulfuric acid solution as a positive / negative electrode solution can obtain an output voltage of about 1.5 V, and therefore has a high energy density. It is efficient.
As a method of obtaining an electrolyte solution for redox batteries, for example, ammonium metavanadate or vanadium pentoxide is reduced with sulfurous acid or the like in the presence of an inorganic acid, and an inorganic acid such as concentrated sulfuric acid is added to the obtained saturated solution, and then a vanadium compound is added. For producing a vanadium-based electrolyte (Japanese Patent Laid-Open No. 5-3039)
No. 73) has been proposed, but this method has a problem that the steps are complicated and it is relatively difficult to produce a stable electrolyte solution.

As an improvement on the above-mentioned conventional method, the present applicant has heated vanadium oxide as a raw material in a reducing atmosphere to convert the vanadium oxide into a vanadium oxide containing V ₂ O ₃ or V ₂ O ₄ as a main component. A vanadium-based electrolyte solution which is reduced and then dissolved in a sulfuric acid solution (Japanese Patent Application No. 7-97902).
No.) has already been proposed.

However, although V ₂ O ₃ can be obtained relatively easily by reduction of oxides, it is not always easy to dissolve V ₂ O ₃ and V ₂ O ₅ alone in sulfuric acid, and it is not practical. It was the upper neck. Therefore, the present invention uses readily available V ₆ O ₁₃ and V ₂ O ₅ as raw materials,
An object of the present invention is to provide a new method for easily and inexpensively producing a high-concentration vanadium solution for a redox battery.

[0007]

In order to solve the above problems, the present invention has conducted various trial and error on a method of dissolving vanadium oxide in sulfuric acid. As a result, V ₂ O ₃ and V ₂ O _{5 were obtained.}
It has been found that an equimolar mixture of the above is rapidly dissolved in sulfuric acid to obtain a tetravalent vanadium solution. That is, the method for producing a vanadium-based electrolytic solution according to the present invention uses the vanadium oxide (main component of which is V ₂ O ₅ or V ₆ O ₁₃ )
Is heated in a reducing atmosphere to reduce V ₂ O ₃ to a vanadium oxide containing V ₂ O ₃ as a main component, and equimolar between V ₂ O ₅ and V ₂ O ₃ in the vanadium oxide obtained above. Is dispersed in water and then dissolved in sulfuric acid to obtain a tetravalent vanadium sulfate (VOSO ₄ ) solution.

As the vanadium oxide as the raw material, it is economical to use an oxide (main component is V ₆ O ₁₃ ) obtained by putting readily available ammonium vanadate into a closed vessel and subjecting it to thermal decomposition. It is.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, this production method will be described in detail with reference to specific examples. The vanadium oxide used in the present invention is obtained, for example, by decomposition of a vanadium compound recovered from a spent catalyst. As a vanadium compound obtained by recovery from the spent catalyst, ammonium metavanadate (NH ₄ VO ₃ ) is generally used.
When this is used, the obtained ammonium metavanadate is placed in a heat-resistant closed container and thermally decomposed.

[0010] The decomposition temperature is preferably 440 to 470 ° C. By maintaining the temperature at this temperature for 7 hours or more, the ammonia of ammonium metavanadate itself is easily decomposed, and the ammonia is used for reduction. After the decomposition, the mixture is cooled to an appropriate temperature, for example, about room temperature, and a vanadium oxide as an intermediate product is taken out.

The oxide obtained by the decomposition of the above ammonium metavanadate is usually one containing V ₆ O ₁₃ as a main component. When this oxide is put in a boat and reduced in an electric furnace in a reducing atmosphere, for example, a hydrogen atmosphere, a low-grade vanadium oxide is obtained. The oxide may be a main component V ₂ 0 ₃ by adjusting the reduction conditions (heating temperature, etc.).

Next, after dispersing equimolar amounts of V ₂ O ₅ and V ₂ O ₃ in the oxide obtained by the above reduction in water,
Add sulfuric acid and heat at 80-120 ° C to dissolve. It is appropriate that the concentration of sulfuric acid is 30 W / V% or more.
0 W / V% or more is preferable, and 50 to 70 W / V% is more preferable. In this case, the concentration of vanadium in the electrolyte for a redox battery can be adjusted to an arbitrary concentration within a practical range, but is preferably about 1 to 3 mol / l. After uniformly dissolving, filtration is performed to obtain a redox battery electrolyte solution of a vanadium solution.

In the present invention, V ₂ O ₃ (trivalent V)
And V ₂ O ₅ (pentavalent V) are dissolved in sulfuric acid. However, since a redox reaction occurs between the trivalent and pentavalent vanadium oxides, the dissolution in sulfuric acid proceeds rapidly, and the chemical formula 1
As shown in (4), a tetravalent vanadium sulfate solution can be easily obtained. In this regard, the method of the present invention is clearly advantageous as compared with the method described in the above-mentioned Japanese Patent Application No. 7-97902, in which V ₂ O ₃ alone is hardly dissolved in sulfuric acid. When V ₂ O ₅ is used as a vanadium compound as a starting material, the process may be started as it is from the hydrogen reduction step as shown by the broken line in FIG.

[0014]

Embedded image

[0015]

EXAMPLE According to the process diagram of FIG. 1, an electrolyte solution for a redox battery was manufactured using ammonium vanadate (ammonium metavanadate), which is a solid recovered from a spent catalyst, as a starting material. First, 6000 g of ammonium metavanadate was placed in a graphite sealed container, and heated in an electric furnace.
Heated. The temperature was raised from room temperature to 470 ° C. over 20 minutes.

Subsequently, at a temperature of 440 to 470 ° C., 7.
After holding for 5 hours, decomposition was performed. After decomposition removed and cooled closed containers, lower oxides V ₆ 0 is an internal intermediate product
₁₃ powder was taken out. The weight of the obtained oxide V ₆ O ₁₃ was 5,280 g.

Next, the obtained V ₆ O ₁₃ powder is divided into small portions, placed in a boat for hydrogen reduction, heated to 700 ° C. in an electric furnace in a hydrogen (air flow) atmosphere, and heated at that temperature for 40 to 60 minutes. To reduce. The hydrogen flow rate was 2.0 m ³ / hr per reduction pipe for inserting a boat into an electric furnace. Powder having been subjected to hydrogen reduction is cooled to obtain a vanadium oxide V ₂ 0 _3. The weight of the obtained oxide was 3770 g.

Furthermore, a mixture of 450g of V ₂ vanadium oxide obtained in 546g and above O ₅ V ₂ O _3, were dispersed by the addition of purified water 4500 ml, concentrated sulfuric acid 5350
g and heated to 80-120 ° C. The dissolved vanadium solution was filtered to obtain a desired product, a redox battery electrolyte comprising a tetravalent vanadium solution. The vanadium concentration of the obtained electrolyte was 51 to 153 g / l (1 to
(3 mol / l).

According to this method for producing a vanadium-based electrolytic solution, a high-concentration tetravalent vanadium sulfate solution can be easily produced using inexpensive ammonium vanadate, which is economical.

[0020]

As described above, according to the method for producing a vanadium-based electrolyte according to the present invention, a high-concentration vanadium-based redox battery electrolyte can be economically produced from inexpensive vanadium oxide as a raw material. It became possible to manufacture easily.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram showing an embodiment of the present invention.

[Chemical formula 1]

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junji Asai 1603-1 Naka-hiroji Higashi-oki, Ako City, Hyogo Prefecture Taiyo Mining Co., Ltd.

Claims (2)

[Claims] A vanadium oxide (main component is V)
₂ O ₅ or V ₆ O ₁₃ ) is heated in a reducing atmosphere to
A step of reducing the ₂ O ₃ in the vanadium oxide as a main component, V ₂ O ₅ and V of the vanadium oxide obtained above
Dispersing an equimolar amount of ₂ O ₃ in water and then dissolving the same in sulfuric acid to obtain a tetravalent vanadium sulfate (VOSO ₄ ) solution. 2. A vanadium oxide as a raw material is an oxide (main component is V ₆ O ₁₃ ) obtained by putting ammonium metavanadate (NH ₄ VO ₃ ) into an airtight container and thermally decomposing the vanadium oxide. 4. The method for producing a vanadium-based electrolytic solution according to 1.