JPH07216570A - Chlorine production method - Google Patents

Abstract

(57) [Abstract] [Purpose] Using a fuel cell system, improving the severity of reaction conditions in conventional chlorine production methods, and extracting electric power to the outside of the reaction system when necessary, is extremely economical. Provide a chlorine production method. [Constitution] A proton conductor is used, a catalyst electrode made of at least one of a metal, a metal compound and a conductive carbonaceous material is used for the anode 1 and the cathode 2, and hydrogen chloride and a cathode are used for the anode chamber 3. Chlorine is produced by the fuel cell system which is constituted by introducing oxygen into the chamber 4 and short-circuiting both electrodes with a lead wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing chlorine by applying a fuel cell system.

Chlorine is used as an oxidizing agent, a bleaching agent and a disinfectant.
It is also an industrially extremely important substance used for the production of dyes, medicines, explosives, bleaching powder and many other useful chlorides.

[0003]

2. Description of the Related Art Salt electrolysis, which is the main industrial chlorine production method at present, meets the demand for chlorine, which has been greatly increased in recent years. This salt electrolysis simultaneously produces caustic soda,
The demand for caustic soda is smaller than that for chlorine, and trying to meet the demand for chlorine by salt electrolysis causes an imbalance between the demand for caustic soda and production. On the other hand, a large amount of hydrogen chloride is by-produced during the chlorination reaction or phosgenation reaction of organic compounds, but since the amount of these by-produced hydrogen chloride is greater than the demand for hydrochloric acid, a large amount of hydrogen chloride is not used. It is disposed of as it is, and in addition, a considerable amount of money is spent on disposal. Therefore, if chlorine can be efficiently recovered from hydrogen chloride, the imbalance between the production of chlorine and caustic soda and the demand can be corrected, and the cost can be further reduced. Deaco has a long history of obtaining chlorine from hydrogen chloride.
Known as the n-reaction, a copper-based catalyst has been considered to be a catalyst exhibiting excellent activity. However, in order to obtain chlorine from hydrogen chloride at an industrially sufficient reaction rate using this catalyst, a reaction temperature of 450 ° C. or higher is required, which causes a problem such as reduction of catalyst life due to scattering of catalyst components. Was becoming.
In order to solve such problems, catalysts other than copper-based catalysts, such as iron-based catalysts, have been proposed, but no catalyst showing practical performance has been known. Recently, a chromium oxide-based catalyst with high activity and long life has been invented. However, all of these methods are not necessarily advantageous from the economical point of view because the reaction is carried out at a high temperature, and oxygen, hydrogen chloride, and chlorine are mixed in the system, which is a safety factor. Is not necessarily advantageous, either.

On the other hand, in recent years, various attempts have been made to produce electric power at the same time as producing various useful compounds under mild conditions using a fuel cell system. A method for producing chlorine from hydrogen chloride by this system is Not yet known.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the conventional problems such as the large consumption of energy in the conventionally known manufacturing method, and prevents oxygen and hydrogen chloride or chlorine from coming into contact with each other, which is extremely simple and safe. With such a reaction system, it is possible to safely produce chlorine from hydrogen chloride under mild conditions and, if necessary, to produce electric power at the same time, thereby increasing economic efficiency. That is, an object of the present invention is to provide a method for producing chlorine from hydrogen chloride, which has extremely high economical efficiency and safety.

[0006]

Means for Solving the Problems As a result of intensive studies on the production of chlorine from hydrogen chloride, the present inventors have found that one electrode of an ion conductor provided with a catalyst electrode is provided with a hydrogen acceptor such as oxygen and the other is not. By using a fuel cell system that consists of contacting hydrogen chloride with the electrodes, we have found that chlorine can be produced at a high selectivity, and at the same time, electric power energy can be taken out when necessary, and the production of chlorine is extremely economical. Completed the method.

That is, the present invention is a method for producing chlorine by a fuel cell system, which comprises bringing one electrode of an ion conductor provided with a catalyst electrode into contact with a hydrogen acceptor and the other electrode into contact with hydrogen chloride. In the present invention, preferably, the catalyst electrode is an electrode containing at least one metal component selected from a metal and / or a metal compound, and the catalyst electrode is an electrode containing a conductive polymer material or a conductive carbonaceous substance. It is also preferable. Further, it is possible to use an electrode which does not contain a metal and / or a metal compound and which is composed of a conductive polymer material such as a conductive carbonaceous material and a binder.

A conceptual diagram of a fuel cell reactor used to carry out the present invention is shown in FIG. An anode chamber 3 having an anode 1 made of a catalyst electrode and a cathode chamber 4 having a cathode 2 are separated by an ion conductor 5, and the anode 1 and the cathode 2 are short-circuited by a lead wire 6. The catalyst electrode is preferably porous or sheet-shaped, but is not limited thereto. If necessary, it is also possible to apply a voltage between the anode and the cathode.

Various materials can be used as the catalyst electrode used in the present invention. In particular, it is recommended to use at least one selected from the group consisting of various metals, metal compounds or conductive polymer materials such as conductive carbonaceous materials. Further, in the case of an electrode using two or more of these, the electrode can be prepared by a method such as mixing and supporting. Further, in order to make the present invention easier to carry out, it is preferable to use an electrode formed by using a binder in addition to these constituent components. However, the invention is not limited to only these methods. As the conductive polymer material used in the present invention,
Generally, it is preferable to use a carbonaceous material such as graphite because of its low cost, availability, and good electric conductivity. Specifically, graphite, activated carbon,
Carbon black, carbon whiskers and the like are mentioned as easily available products.

Various binders can be used as the binder used for molding the electrode. However, from the viewpoint of ease of molding, etc., hot pressing using Teflon resin powder is preferred. Is preferred. However, the invention is not limited to only these materials and methods.

In the present invention, the metal used for the catalyst electrode and / or the metal composing the metal compound is, in the periodic table, a group 3, a group 4, a group 5, a group 6, a group 7, and a group 8 of the periodic table. , 9th, 10th, 11th, 12th, 13th
It is one or more metals selected from the group consisting of Group 14 and Group 14 metals. Specifically, the Group 3 metals are metals represented by the element symbols Sc, Y, La, Ac, etc., and the Group 4 metals are the element symbols Ti, Zr, Hf.
And the like, the Group 5 metal is a metal and the like represented by the element symbols V, Nb, Ta, and the like, and the Group 6 metal is a element represented by the elements Cr, Mo, W, and the like. And the like, and the Group 7 metals include the element symbols Mn, Tc, Re
Is a metal represented by
e, Ru, and Os, and the Group 9 metal is a metal represented by the element symbols Co, Rh, and Ir.
The Group 10 metal is a metal represented by the element symbols Ni, Pd, and Pt, and the Group 11 metal is the element symbol Cu,
The metals represented by Ag and Au, and the Group 12 metals are metals represented by the element symbols Zn, Cd, and Hg.
The Group 3 metal is, for example, a metal represented by Al, Ga, In, Tl or the like, and the Group 14 metal is Si as an element symbol.
A metal or the like represented by Ge, Sn, Pb or the like. The metal compound used in the present invention is not particularly limited, and various compounds such as an inorganic compound and an organic metal compound are used, preferably a halide, an oxide, a hydroxide, a nitrate, a sulfate, Examples of readily available metal compounds include acetates. However, the catalyst electrode may be an electrode containing only a conductive polymer material or a conductive carbonaceous material.
In the present invention, the anode (catalyst electrode) 1 and the cathode (catalyst electrode) 2 each include at least one or more selected from the group of various polymer materials such as various metals, metal compounds or conductive carbonaceous materials. It is desirable that the electrodes include. However, the anode (catalyst electrode) 1 may be an electrode made only of a conductive polymer material such as a conductive carbonaceous substance. Further, a catalyst electrode for contacting hydrogen chloride, that is, an anode (catalyst electrode) 1 is an electrode containing a conductive polymer material such as a conductive carbonaceous material, and a catalyst electrode for contacting a hydrogen acceptor, that is, a cathode (catalyst electrode). 2) can be an electrode containing at least one metal component selected from metals and / or metal compounds.

The periodic table used in the present invention is a periodic table based on the International Union of Pure and Applied Chemistry Nomenclature of Inorganic Chemistry (1989).

Examples of the ionic conductor used in the present invention include protonic acids such as phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid, heteropolyacids, solid electrolytes known as proton conductors such as H-montmorillonite and zirconium phosphate, and SrCe.
A perovskite type solid solution having O ₃ as a matrix can be used. Further, a fluoropolymer such as perfluorocarbon is used as a base, and one or more cation exchange groups such as sulfonic acid groups or carboxylic acid groups are introduced into the base, for example, Nafion (registered trademark of DuPont) is also used. it can. The liquid such as phosphoric acid may be used as it is, but it may be used by impregnating it with silica wool or the like, or may be used by sandwiching it with an ion-permeable filter or membrane.

The hydrogen chloride used in the present invention is usually supplied to the anode as a gas, but it may be dissolved in an appropriate solvent and supplied, or hydrochloric acid water may be used. When used as a gas, it does not necessarily have to be a pure substance, and may be a mixture with an inert gas such as nitrogen, helium, or argon, may contain water vapor, and may be dried. . For example, it may be a hydrogen chloride-containing gas obtained by passing hydrochloric acid water through another gas. The supply system may be either a continuous system or a batch system, but when it is supplied as a gas, the continuous system is desirable. The hydrogen acceptor used in the present invention is a substance capable of taking in hydrogen by a reaction with reduced hydrogen on the cathode (catalyst electrode) in the fuel cell system, such as molecular oxygen, unsaturated hydrocarbon, carbonyl. Examples thereof include compounds, nitro compounds, organic peroxides and inorganic peroxides, and oxygen molecules are preferably used in the present invention. Further, the hydrogen acceptor to be supplied does not necessarily have to be a pure substance, and is usually supplied as a gas or a liquid, but if necessary, it may be dissolved in a medium suitable for this reaction and brought into contact with the electrode in a liquid phase state. There is no problem, and the gas may be brought into contact with the electrode in a gas phase as a mixed gas with an inert gas such as nitrogen, helium or argon. The supply method is also not particularly limited, and may be a continuous method or a batch method. For example, when supplying in a gas phase, a continuous system is preferable. The reaction form is not particularly limited, and it may be carried out in any form such as liquid phase, gas-liquid phase and gas phase. When it is carried out in the liquid phase, vigorous stirring is preferable in order to effectively make contact with the catalyst electrode. The reaction temperature is not particularly limited, but it is generally preferably in the range of -20 ° C to 200 ° C, more preferably 0 ° C to 100 ° C. If the temperature is too low, the reaction rate is lowered and energy such as cooling is required, and if the temperature is too high, energy such as heating is required, which is not efficient. Also, according to the invention, the reaction is generally carried out at normal pressure,
If necessary, it can be carried out under pressure or under reduced pressure. Chlorine, which is a reaction product, can be obtained as a gas or can be obtained by dissolving it in a suitable solvent.

[0015]

EXAMPLES The present invention will be described in more detail based on the following examples. However, these are exemplary,
The invention is not limited by these examples. In the symbols described in this example, mF represents millifaradaic and μmol represents micromol. The generated chlorine gas is absorbed by water to remove chlorine contained in the aqueous solution.
It was quantified by the color reaction of o-tolidine which is specified in IS standard K0102. Chlorine absorbed in the cathode, anode and ionic conductor was also quantified by extracting with water.

Example 1 Preparation of catalyst electrode (a) Preparation of anode Platinum black powder (20 mg), graphite powder (50 mg) and Teflon powder (7 mg) were thoroughly mixed and hot pressed to form a circular sheet, which was used as an anode. (B) Preparation of Cathode 150 mg of palladium black powder and 15 mg of Teflon powder were mixed well, and this was formed into a circular sheet by hot pressing to obtain a cathode. Two disc-shaped glass wools (thickness 1.0 mm, diameters 21 mm and 24 mm) were impregnated with a 5M phosphoric acid aqueous solution, and a Nafion membrane impregnated with a 5M phosphoric acid aqueous solution was sandwiched therebetween as an ion conductor membrane. The above-mentioned anode and cathode were attached to the anode chamber and the cathode chamber, respectively. Moreover, the anode and the cathode were connected by a conductive wire to form a closed circuit. Argon gas passed through concentrated hydrochloric acid was supplied to the anode chamber at a flow rate of 200 ml / min. Oxygen was supplied to the cathode chamber at a flow rate of 200 ml / min. Reaction time 2.5 hours, reaction temperature 23 ℃
The reaction was carried out. As a result, as shown in Table 1, generation of electric current was recognized together with generation of chlorine.

Example 2 The reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 100 ° C. The results are shown in Table 1.

Example 3 The reaction was carried out under the same conditions as in Example 2 except that the black metal used for the anode was palladium black powder instead of platinum black powder. The results are shown in Table 1.

Comparative Example 1 The reaction was performed under the same conditions as in Example 3 except that the cathode and anode were in an open circuit state (no connection between the electrodes). As a result, no chlorine production was found.

Example 4 The reaction was carried out under the same conditions as in Example 2 except that the metal used for the anode was ruthenium black powder instead of platinum black powder. The results are shown in Table 1.

Example 5: Instead of the platinum black powder used for the anode, silica having 70% by weight of chromia supported thereon was used.
The reaction was carried out under the same conditions as in Example 2. The results are shown in Table 1.
It was shown to.

Example 6 The reaction was carried out under the same conditions as in Example 2 except that 70 mg of carbon whisker powder and 7 mg of Teflon powder were used instead of a metal for the preparation of the anode. The results are shown in Table 1.

Example 7 70 mg of activated carbon powder without using metal for the preparation of anode
And prepared using only Teflon powder 7 mg,
The reaction was carried out under the same conditions as in Example 2. The results are shown in Table 1.
It was shown to.

Example 8 Graphite powder 7 was prepared without the use of metal in the preparation of the anode.
The reaction was carried out under the same conditions as in Example 2, except that only 0 mg and Teflon powder 7 mg were used. The results are shown in Table 1.

[0025]

[Table 1] Table 1 ──────────────────────────────────── Example Reaction temperature Current flow Chlorine formation Amount (° C) (μF) (μmol) ──────────────────────────────────── Example 1 23 47.2 45.3 Example 2 100 66.3 64.3 Example 3 100 229.6 219.1 Example 4 100 12.9 12.0 Example 5 100 28.9 27.7 Example 6 100 221.2 211.4 Example 7 100 190.0 179.5 Example 8 100 151.3 124.7 ──────────────────────── ─────────────

[0026]

According to the present invention, the following effects can be obtained. (1) Under extremely mild conditions, chlorine can be produced from hydrogen chloride without the formation of a large amount of by-products. (2) When carrying out the reaction, the energy change of the reaction can be taken out of the reaction system as electric energy (electric power) if necessary, and the electric power can be used as a by-product, which is extremely economical. Can produce chlorine.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a fuel cell reactor.

[Explanation of symbols]

 1 Anode (catalyst electrode) 2 Cathode (catalyst electrode) 3 Anode chamber 4 Cathode chamber 5 Ion conductor 6 Lead wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01M 8/22 9444-4K

Claims (8)

[Claims] 1. A method for producing chlorine by a fuel cell system, which comprises contacting one electrode of an ion conductor provided with a catalyst electrode with a hydrogen acceptor and contacting the other electrode with hydrogen chloride. 2. The method according to claim 1, wherein the catalyst electrode is an electrode containing at least one metal component selected from metals and / or metal compounds. 3. The method according to claim 1, wherein the catalyst electrode is an electrode containing a conductive polymer material. 4. A catalyst electrode for contacting hydrogen chloride is an electrode containing a conductive polymer material, and a catalyst electrode for contacting a hydrogen acceptor contains at least one metal component selected from metals and / or metal compounds. The method according to claim 1, which is an electrode. 5. The method according to claim 3, wherein the conductive polymer material is a conductive carbonaceous material. 6. A metal constituting a catalyst electrode and / or a constituent metal of a metal compound is selected from Group 3, Group 4, Group 5, Group 6, Group 7, Group 8 and Group 3 of the periodic table. 9th group, 1st
The method according to claim 2 or 4, which is one or more metals selected from the group consisting of Group 0, Group 11, Group 12, Group 13 and Group 14 metals. 7. The method according to claim 1 or 4, wherein the hydrogen acceptor is a molecular oxygen. 8. The method according to claim 5, wherein the conductive carbonaceous substance is at least one selected from the group consisting of activated carbon, graphite, carbon black and carbon whiskers.