JP2006307333A - Method for processing hydrogen sulfide, method for producing hydrogen and photocatalytic reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of decomposing hydrogen sulfide and producing hydrogen efficiently by using a photocatalyst. <P>SOLUTION: In the method for treating hydrogen sulfide and the method for producing hydrogen, a liquid tank having at least a photocatalyst electrode 1 made of photocatalyst and a liquid tank having a metal electrode 2 are separated by a cation exchange film 3, liquid including hydrogen sulfide or organic substance is stored in the liquid tank having the photocatalyst electrode 1, the photocatalyst electrode 1 is electrically connected with the metal electrode 2 and the photocatalyst is exposed to light. An acidic solution is preferably stored in the liquid tank having the metal electrode 2, and the photocatalyst preferably includes metal sulfide and is preferably formed as fine particles having a lamellar nanocapsule structure. A reactor may be an electrolysis cell 11 in which a photoelectrochemical cell is included. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention can be used in the chemical industry field requiring hydrogen, sulfur, etc., the chemical industry field for treating hydrogen sulfide generated in the desulfurization process, and the environmental conservation field for removing malodorous substances and air pollutants. The present invention relates to a method of using a photocatalyst.

  The application of photocatalytic technology has begun to be put into practical use by utilizing characteristics that promote various chemical reactions, such as decomposition of environmental pollutants, malodorous components and bacteria. Examples include antibacterial tiles used in hospital operating rooms, filters for air cleaners and air conditioners, and glass for lighting on highways. While these photocatalysts have been put into practical use using the ability to promote oxidation, research aimed at obtaining hydrogen by acting a photocatalyst on water, etc., and fixing carbon by acting on carbon dioxide gas has also been conducted. Yes.

  On the other hand, from the viewpoint of environmental problems such as depletion of fossil energy resources and air pollution due to global warming, establishment of clean and safe energy acquisition technology and purification technology of environmental pollutants is required. Among them, the use of a photocatalyst is promising. For example, it can be considered that the photocatalyst is applied to a desulfurization process of crude oil or metal smelting.

  Currently, in the crude oil desulfurization process, a heavy naphtha is produced by hydrogenation to recover all sulfur components contained in crude oil as hydrogen sulfide when the crude oil is distilled. This hydrogen sulfide passes through a process called the Claus method and oxidizes and recovers sulfur. The Claus method is a process in which one-third of hydrogen sulfide is oxidized to sulfurous acid gas, and this is reacted with the remaining hydrogen sulfide to form element ions.

  In this process, enormous energy is required not only for the catalytic reaction of sulfurous acid gas and hydrogen sulfide, but also for repeated heating and condensation. In addition, there is a problem such as costly management of sulfurous acid gas. Add photocatalyst to alkaline water in which hydrogen sulfide is dissolved, irradiate light, absorb the light energy of the irradiated light, and redox the alkaline water in which hydrogen sulfide is dissolved by free electrons and free holes generated by the photocatalyst, If a method for obtaining hydrogen and sulfur, that is, a method for decomposing hydrogen sulfide with a photocatalyst to produce hydrogen and sulfur can be put into practical use, hydrogen sulfide that is a harmful substance is decomposed with less energy, and hydrogen and sulfur that are useful substances are decomposed. Can be produced. That is, it contributes to the solution of environmental problems and can produce useful substances.

On the other hand, as a method of generating hydrogen by electrolysis, a method of performing electrolysis of water by an electromotive force of a solar cell is performed. However, in this process, the efficiency of electrolysis is determined depending on the performance of the solar cell. And since the element which comprises a high performance solar cell is a high purity and high quality element, there existed a problem that it was expensive.
Also in this regard, if a method for decomposing water using a photocatalyst to generate hydrogen can be put to practical use, it becomes possible to produce hydrogen with less energy and cost.

  However, the conventional photocatalyst has the following problems to be solved. First, the catalytic activity is low. Second, the photocatalyst is toxic. When the photocatalyst is irradiated with light, free electrons and free holes (holes) are generated, but there is a high probability that they will recombine, and chemical substances decomposed by the oxidation-reduction reaction will recombine and return to the original compound And the catalytic activity is low. Third, the life of the catalyst is short. When photocatalyst is irradiated with light, free electrons and free holes are generated, but due to its strong redox reaction, the catalyst itself is oxidized and reduced in addition to the target chemical substance and dissolved, resulting in loss of catalytic action. There is a problem.

On the other hand, Patent Document 1 discloses that a photocatalyst having high catalytic activity, no toxicity, and a long lifetime is disclosed to solve the above three problems.
Further, a hydrogen sulfide treatment method, a hydrogen production method, or the like using a stratified structure electrode in which a metal is activated as a photocatalyst is known.
JP 2001-190964 A

However, in the stratified structure electrode, the metal side is corroded by hydrogen sulfide, or polysulfide ions (S ₂ ²⁻ ) are adsorbed on the metal surface to form sulfides, and hydrogen gas is generated from hydrogen ions (H ⁺ ). The metal surface portion for generating the gas was lost, and there was a problem that hydrogen gas could not be generated, and it was still not efficiently satisfied.
Accordingly, an object of the present invention is to overcome the above-mentioned drawbacks of the prior art and provide a technique enabling the decomposition of hydrogen sulfide and the production of hydrogen with high efficiency using a photocatalyst, and an apparatus used in this technique. That is.

As a result of intensive studies, the present inventors have been able to solve the above problems by adopting the following configuration. That is, the present invention is as follows.
(1) A liquid tank having at least a photocatalyst electrode composed of a photocatalyst and a liquid tank having a metal electrode are separated by a cation exchange membrane, and a liquid containing hydrogen sulfide is accommodated in the liquid tank having the photocatalyst electrode. A method for treating hydrogen sulfide in which an electrode and the metal electrode are electrically connected and the photocatalyst is exposed to light.
(2) The method for treating hydrogen sulfide according to (1), wherein the liquid stored in the liquid tank having the metal electrode is an acidic solution.
(3) The method for treating hydrogen sulfide according to claim 1, wherein the photocatalyst contains a metal sulfide.
(4) The method for treating hydrogen sulfide according to (1), wherein the photocatalyst is a fine particle having a layered nanocapsule structure.

(5) The method for treating hydrogen sulfide according to (1), wherein the liquid containing hydrogen sulfide is obtained by blowing hydrogen sulfide gas into an alkaline liquid and dissolving it.
(6) The hydrogen sulfide gas is obtained by blowing a gas containing hydrogen sulfide and carbon dioxide into a methyldiethanolamine solution, and then heating the methyldiethanolamine solution to a temperature higher than room temperature and blowing in air. 5) The processing method of hydrogen sulfide as described.

(7) A liquid tank having at least a photocatalytic electrode composed of a photocatalyst and a liquid tank having a metal electrode are separated by a cation exchange membrane, and the liquid tank having the photocatalytic electrode contains a liquid containing hydrogen sulfide or an organic substance, A method for producing hydrogen, wherein the photocatalyst electrode and the metal electrode are electrically connected and the photocatalyst is exposed to light.
(8) The method for producing hydrogen according to (7), wherein the liquid stored in the liquid tank having the metal electrode is an acidic solution.
(9) The method for producing hydrogen according to claim 7, wherein the photocatalyst contains a metal sulfide.
(10) The method for producing hydrogen according to (7), wherein the photocatalyst is a fine particle having a layered nanocapsule structure.

(11) The method for producing hydrogen according to (7), wherein the liquid containing hydrogen sulfide is obtained by blowing hydrogen sulfide gas into an alkaline liquid and dissolving it.
(12) The hydrogen sulfide gas is obtained by blowing a gas containing hydrogen sulfide and carbon dioxide into a methyldiethanolamine solution, then heating the methyldiethanolamine solution to a temperature higher than room temperature and blowing in air. 11) The method for producing hydrogen according to the above.

(13) a first liquid tank having at least a photocatalyst electrode made of a photocatalyst and containing a liquid containing hydrogen sulfide; and a second liquid tank having a metal electrode; The photocatalyst reaction apparatus is configured such that the photocatalyst electrode and the metal electrode are electrically connected to each other and can be irradiated with light. .
(14) A first liquid tank that contains a liquid containing hydrogen sulfide, and a second liquid tank provided in the first liquid tank, and a partition material for the second liquid tank 1 part consists of a member in which a photocatalyst layer is formed on one side of the conductive plate and a metal layer is formed on the opposite side, and the side having the photocatalyst layer is on the outside and the side having the metal layer is on the inside The other part of the partition material of the second liquid tank is composed of a cation exchange membrane, and is configured so that light can be irradiated onto the photocatalyst layer. apparatus.
(15) The photocatalytic reaction device according to (13) or (14), comprising means for supplying or circulating an acidic solution to the second liquid tank.

  According to the present invention, hydrogen sulfide can be efficiently decomposed directly with a photocatalytic electrode and light can be produced with a metal electrode by light energy such as visible light.

Embodiments of the present invention will be described below in detail with reference to the drawings. However, the present invention is not limited to these embodiments.
Note that components having the same function are denoted by the same reference symbols in the two drawings illustrating the embodiments, and the repetitive description thereof is omitted.
FIG. 1 is a diagram schematically showing an embodiment of an apparatus for performing hydrogen sulfide treatment and hydrogen production according to the present invention.
The apparatus shown in FIG. 1 is based on the basic principle of electrolyzing a liquid to be treated by photovoltaic power between a semiconductor photocatalyst electrode and a metal electrode. First, the configuration of the apparatus will be described, and then the operation will be described.

  In FIG. 1, an electrolysis cell 11 is separated by a cation exchange membrane 3, with a photocatalytic electrode 1 on the anode side (left side in FIG. 1) and a metal electrode 2 on the cathode side (right side in FIG. 1). Are provided, and the photocatalytic electrode 1 and the metal electrode 2 are configured to be electrically connected from a conductive wire 4 that is a conductive member.

In order to perform the treatment of hydrogen sulfide and the production of hydrogen using the electrolytic cell (cell) 11 configured as described above, the photoelectromotive force between the photocatalyst electrode 1 and the metal electrode 2 contains hydrogen sulfide and the like. Electrolyze the liquid.
The photocatalytic electrode 1 decomposes hydrogen sulfide ions (HS ⁻ ) in the hydrogen sulfide water into hydrogen ions (H ⁺ ) and polysulfide ions (S ₂ ²⁻ ) using light energy. Electrons and hydrogen ions generated at the time of decomposition move to the metal electrode through the conductive member (electrons) and the cation exchange membrane (hydrogen ions), reduce the hydrogen ions at the metal electrode 2, and generate hydrogen gas.
The reaction formula of the above two steps is shown by the following formula.

2HS ⁻ → 2H ⁺ + S ₂ ²⁻ (photocatalytic electrode)
2H ⁺ + 2e ⁻ → H ₂ (metal electrode)

FIG. 6 is a diagram schematically showing another embodiment of the apparatus for carrying out the treatment of hydrogen sulfide and the production of hydrogen according to the present invention.
FIG. 1 shows a photocatalytic reaction in which an electrolysis cell 11 is divided into a first liquid tank having a photocatalytic electrode 1 and a second liquid tank having a metal electrode 2 by a cation exchange membrane 3. FIG. 6 is a schematic cross-sectional view of a photocatalytic reaction device having a second liquid tank in a liquid tank that contains a liquid containing hydrogen sulfide.

  In FIG. 6, the photocatalytic reaction apparatus includes an electrolysis cell 11 (first liquid tank) in which an outer side of a conductive plate 33 such as a titanium plate is one of partition walls, and a photocatalytic layer 31 (photocatalytic electrode 1). Thus, the inner side is formed of the metal layer 32 (metal electrode 2), and the photoelectrochemical cell 34 (second liquid tank) configured by the cation exchange membrane 3 is provided as the other partition wall material. Has been.

Between the photocatalyst electrode 1 (photocatalyst layer 31) and the metal electrode 2 (metal layer 32) in order to perform hydrogen sulfide treatment and hydrogen production using the electrolytic cell (cell) 11 configured as described above. Electrolysis of liquid containing hydrogen sulfide and the like is performed by photovoltaic power.
The photocatalytic electrode 1 decomposes hydrogen sulfide ions (HS ⁻ ) in the hydrogen sulfide water into hydrogen ions (H ⁺ ) and polysulfide ions (S ₂ ²⁻ ) using light energy. Electrons and hydrogen ions generated during decomposition move to the metal electrode 2 in the second liquid tank through the conductive member (electrons) and the cation exchange membrane (hydrogen ions), and the metal electrodes 2 reduce the hydrogen ions. Then, hydrogen gas is generated.
The reaction formula of the above two steps is as shown in the above formula.

The photocatalytic reaction apparatus according to the present invention can irradiate the photocatalytic electrode 1 with light regardless of the cation exchange membrane separation system shown in FIG. 1 or the photoelectrochemical cell housing system shown in FIG. It is an indispensable requirement to constitute so that.
For that purpose, for example, the ceiling portion of the device (electrolysis cell 11 or first liquid tank) is exposed to a light transmissive (transparent) material (for example, so as to be exposed to light sources such as sunlight and a lamp from the outside of the device. (Acrylic resin) or the wall material of the first liquid tank facing the photocatalyst electrode 1 (photocatalyst layer 31) needs to be composed of a light transmissive (transparent) material.
However, when a light source (lamp or the like) having a waterproof property is put in the liquid of the first liquid tank, this is not the case. Rather, the electrolysis cell 11 or the photocatalyst electrode 1 (photocatalytic layer of the first liquid tank). It is preferable that the wall inner surface facing 31) is formed as a light reflecting surface (mirror surface or the like).

  In the photocatalytic reaction apparatus in which the second liquid tank is provided in the first liquid tank, the second liquid tank (photoelectrochemical cell 34) is not necessarily provided vertically as shown in FIG. Alternatively, the acidic solution may be installed obliquely so that the means for supplying or circulating the acidic solution comes upward. However, in this case, it goes without saying that it is convenient to place the photocatalyst layer 31 (photocatalyst electrode 1) on the upper surface in order to facilitate light irradiation to the photocatalyst layer 31. Needless to say, the acidic solution circulation means may be configured such that the acidic solution inlet is on the lower side and the outlet is on the upper side, and the generated hydrogen is easily removed.

  In the photocatalytic reaction device according to the present invention, it is preferable to have means for supplying or circulating the acidic solution to the second liquid tank. By providing such means, the hydrogen ion concentration of the liquid in the second liquid tank is increased, the initial reaction efficiency is further improved, and it is effective in improving the hydrogen sulfide removal efficiency and the hydrogen generation efficiency. In addition, the desorption of hydrogen bubbles generated on the metal electrode is improved, and stable hydrogen generation is possible (reason: if bubbles remain attached, the reaction surface covers the bubbles and the hydrogen reduction reaction occurs. It becomes difficult.) Further, hydrogen bubbles can be taken out of the cell together with the flow of the acidic solution, and hydrogen can be easily recovered (reason: if the bubbles are not circulated, the bubbles will accumulate inside the cell).

Below, each structural member which forms the apparatus which concerns on this invention is demonstrated in detail.
Although it does not specifically limit as a photocatalyst which is a component of the photocatalyst electrode which consists of a photocatalyst used at least by this invention, The thing containing a metal sulfide is preferable. The reason why a metal sulfide is contained is that hydrogen sulfide ions (HS ⁻ ) are adsorbed on the surface of the metal sulfide to reduce the hydrogen generation potential, and the reduction and self-healing action by HS ⁻ against the elution of metal elements. This results in the formation of a stable and long-life electrode without corrosion.
Here, examples of the metal sulfide include cadmium sulfide and zinc sulfide that can use visible light such as sunlight as it is for a photocatalytic reaction.

As a form of the photocatalyst, those having an arbitrary shape such as a particulate form or a thin film form can be used without any limitation.
As the particles, fine particles having a layered nanocapsule structure disclosed in JP-A Nos. 2003-265962 and 2004-25032 are preferable because of high catalytic activity.
Further, as a thin film photocatalyst, a thin film photocatalyst deposited on a substrate made of silicon, glass, nickel, zinc, platinum, resin, etc., as disclosed in JP-A-2003-181297 is handled. In addition to being convenient, it is possible to produce a photocatalyst with a large area with a small amount of catalyst, and because it is fixed on the substrate without being dispersed in the solution like particles, the irradiation angle is optimized. Thus, it can be said that the catalyst has a preferable shape because it has the advantage that the conversion efficiency of the energy of irradiation light can be improved.
Further, by fixing fine particles having a layered nanocapsule structure and forming electrodes, higher activity can be obtained by increasing the reaction surface area.

  Although it does not specifically limit as the metal electrode 2 used as a cathode with respect to the above-mentioned photocatalyst electrode 1 used as an anode, The metal which has activity in hydrogenation reaction, such as platinum and nickel, is preferable, and especially platinum is the most preferable.

  In the second liquid tank (photoelectrochemical cell 34) of FIG. 6, the conductive plate 33 forming the photocatalyst layer 31 and the metal layer 32 is made of a conductive material made of titanium, zirconium, nickel, zinc, platinum or the like. Although it is necessary to be a plate-like base material, a titanium plate is chemically stable, strong, and light, and is used for a piping material for a plant, an aircraft part, and the like.

The cation exchange membrane is not particularly limited as long as it has hydrogen ion selective permeability. By this cation exchange membrane, anions such as OH ⁻ and SH ⁻ and dissolved substances and precipitates such as O ₂ and S ₂ in the liquid tank having the photocatalytic electrode 1 move into the liquid tank having the metal electrode 2. Therefore, only the H ⁺ ions are selectively moved, and the concentration of H ⁺ in the metal electrode immersion bath is increased, and as a result, the generation amount of hydrogen gas is increased.

The liquid containing hydrogen sulfide, which is the liquid to be treated used in the hydrogen sulfide treatment method and the hydrogen production method of the present invention, was generated in the hydrogen sulfide-containing waste liquid and petroleum desulfurization process of sulfuric acid and sulfur-based insecticide manufacturing plants. To treat hydrogen sulfide containing wastewater or hot water wastewater from the beginning, and hydrogen sulfide gas as one of the raw materials in the chemical industry that requires hydrogen, sulfur, etc. In addition, it includes both liquids to be treated in which hydrogen sulfide gas is blown into a liquid such as water. In the latter case, it is well known in the art to make the hydrogen sulfide-containing liquid alkaline by adding an alkaline agent such as sodium hydroxide in order to enhance the solubility of the hydrogen sulfide gas. By making the liquid in the tank of the photocatalyst electrode alkaline, the hydrogen sulfide ion (HS ⁻ ) concentration can be increased and the hydrogen generation potential can be decreased.

  In the hydrogen sulfide treatment method and hydrogen production method of the present invention, hydrogen sulfide gas generated in a sewage treatment plant or the like can also be treated. In this case, the gas containing hydrogen sulfide generated in a sewage treatment plant or the like contains a large amount of carbon dioxide. Even if such a gas containing hydrogen sulfide and carbon dioxide is blown into the alkaline liquid as described above, the absorption / dissolution efficiency of hydrogen sulfide into the alkaline liquid is reduced due to the influence of carbon dioxide.

Therefore, a gas containing hydrogen sulfide and carbon dioxide as described above is blown into a methyldiethanolamine aqueous solution or the like, for example, at room temperature (room temperature), thereby absorbing and dissolving hydrogen sulfide in the methyldiethanolamine solution. Carbon can be discharged without being absorbed and dissolved in the methyldiethanolamine solution. Next, the methyldiethanolamine solution in which hydrogen sulfide is absorbed / dissolved is heated to a temperature higher than room temperature (for example, about 70 ° C.) and air is blown to remove the hydrogen sulfide absorbed / dissolved from the methyldiethanolamine solution. It is possible to obtain a hydrogen sulfide gas having high purity (concentration) that is desorbed and does not contain (almost) carbon dioxide. In addition, the obtained high-purity hydrogen sulfide gas is again or repeatedly subjected to the same treatment several times, so that the remaining carbon dioxide can be further removed to obtain a higher-purity hydrogen sulfide gas.
The obtained hydrogen sulfide gas containing no carbon dioxide and having a high purity is blown into an alkaline liquid, whereby the “liquid containing hydrogen sulfide” of the present invention can be obtained.

The above-described treatment process for obtaining high-purity hydrogen sulfide gas by removing carbon dioxide from the gas containing hydrogen sulfide and carbon dioxide generated in a sewage treatment plant will be described in more detail with reference to the drawings.
For example, only the gas containing hydrogen sulfide and carbon dioxide is blown into the methyldiethanolamine solution by using an apparatus / apparatus having a schematic configuration shown in FIG. The apparatus / apparatus having a schematic configuration shown in FIG. 3 includes at least a cleaning bottle 21, an air pump 22, and an air supply pipe. The cleaning bottle 21 contains a methyldiethanolamine solution, and the air pump 22 supplies a gas containing hydrogen sulfide and carbon dioxide.・ Air is sent.

  Desorption of the hydrogen sulfide from the methyldiethanolamine solution in which hydrogen sulfide is absorbed and dissolved can be performed using, for example, an apparatus / apparatus having a schematic configuration shown in FIG. 4 includes at least a heating unit 23 such as a water bath and a cooling unit 24 such as a mist separator for removing water vapor and the like. The methyldiethanolamine solution in which hydrogen sulfide is absorbed and dissolved by the heating means 23 is heated, and air is supplied and supplied by the air pump 22. The air discharged by blowing into the heated methyldiethanolamine solution contains hydrogen sulfide and water vapor. This water vapor is removed and separated by the cooling means 24.

  When the high-purity hydrogen sulfide gas not containing carbon dioxide thus obtained is blown into the alkaline liquid, for example, an apparatus / apparatus having a schematic configuration shown in FIG. 3 can be used. An alkaline liquid is accommodated in the cleaning bottle 21, and high-purity hydrogen sulfide gas is supplied and supplied by the air pump 22. Thereby, it can be set as the "liquid containing hydrogen sulfide" of this invention.

  On the other hand, the liquid stored in the liquid tank impregnated with the metal electrode 2 as the cathode does not necessarily need to be acidic, but the acidic reaction has better initial reaction efficiency and improved hydrogen sulfide removal efficiency and hydrogen generation rate. To do. Even if the liquid contained in the liquid tank impregnated with the metal electrode 2 is not acidified, the hydrogen ion concentration of the liquid in the tank gradually increases as the reaction proceeds, and the reaction efficiency is gradually improved.

  By using the apparatus and the liquid to be treated as described above, the method of the present invention in which hydrogen sulfide is decomposed directly by a photocatalytic electrode by light energy such as sunlight and hydrogen is produced by a metal electrode is carried out with high efficiency. It becomes possible.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to the examples.
[Example 1]
First, the apparatus used in the embodiment will be described with reference to FIG. 2, and then the operation procedure will be described.
As shown in FIG. 2, an apparatus for performing hydrogen generation experiments by treating hydrogen sulfide with a photocatalyst is an acrylic resin cylinder that immerses the photocatalyst electrode 1 as an anode and fills a 0.1 mol / liter sodium sulfide solution. A tube 5 and a transparent vinyl chloride resin cylindrical tube 6 filled with a 0.1 mol / liter sulfuric acid solution immersed in a metal electrode 2 serving as a cathode are connected, and the central portion of the bridge is separated by a cation exchange membrane 3 The bottom portions are connected to each other by a rigid vinyl chloride tube 7 which is a connecting tube of the two electrode tanks, and is integrally formed. Reference numeral 8 denotes an Xe irradiation lamp for light irradiation, and reference numeral 4 denotes a conductive wire for electrically connecting the photocatalytic electrode 1 and the metal electrode 2.

The photocatalyst electrode was used by immobilizing cadmium sulfide on a conductive ITO glass according to the method disclosed in Japanese Patent Application Laid-Open No. 2003-181297, and manufacturing the electrode with a size of 80 mm × 15 mm.
On the other hand, although the platinum electrode was used for the metal electrode, the electrode size was 4 mmφ × 80 mm.
The conducting wire 4 connecting the photocatalytic electrode 1 and the metal electrode 2 was a copper wire, and the electrodes 1 and 2 were electrically connected with an alligator clip.

The light receiving part of the photocatalyst electrode 1 was made of a transparent acrylic resin, and the other tank container part was made of a transparent vinyl chloride resin and a hard vinyl chloride resin.
Each capacity of one tank of photocatalyst electrode and two tanks of metal electrode is 60 ml.

Using the apparatus having the above-described configuration, energizing between both electrodes and irradiating Xe light from the Xe irradiation lamp, the amount of hydrogen generation increases in proportion to the irradiation time. This was confirmed by visual observation.
The reason why the Xe irradiation lamp is used as the light source is to perform experiments quantitatively, and it goes without saying that sunlight can be used as the light source practically.

[Example 2]
This was carried out assuming gas treatment containing hydrogen sulfide and carbon dioxide generated from a sewage treatment plant.
First, hydrogen sulfide gas is separated from a gas containing a large amount of carbon dioxide by a hydrogen sulfide gas separation step, and the obtained hydrogen sulfide gas is absorbed into an alkali solution by a hydrogen sulfide gas dissolution step to obtain a hydrogen sulfide solution. It was. This hydrogen sulfide solution was decomposed by the photocatalyst in the photocatalytic reaction step to generate hydrogen.

  As shown in FIG. 3, 200 liters of mixed gas containing 200 ppm hydrogen sulfide and 32% carbon dioxide is supplied to the gas washing bottle at a flow rate of 1 liter / min by the air pump 22, and 45 wt% methyldiethanolamine in the gas washing bottle 21. Hydrogen sulfide was absorbed into 200 milliliters of the solution. Carbon dioxide is hardly absorbed by the methyldiethanolamine solution and discharged from the washing bottle.

As shown in FIG. 4, the washing bottle 21 containing the liquid in which hydrogen sulfide is absorbed is heated with hot water (water bath: heating means 23) at 70 ° C., and the air is supplied by the air pump 22 to 3.7 liter / min. The gas was supplied to the gas washing bottle at a flow rate of aeration to perform aeration, desorb the gas absorbed in the absorption liquid, and collect the gas.
The amount of gas recovered was 170 liters, the hydrogen sulfide concentration was 176 ppm, and the carbon dioxide concentration was 0.9%.

As shown in FIG. 3, the recovered gas is supplied again to the gas washing bottle 21 with an air pump at a flow rate of 1 liter / min, and hydrogen sulfide is absorbed into 200 ml of the 45 wt% methyldiethanolamine solution in the gas washing bottle 21. Then, as shown in FIG. 4, the washing bottle 21 containing the liquid in which hydrogen sulfide has been absorbed is heated with hot water at 70 ° C., and air is supplied by the air pump 22 at a flow rate of 3.7 liter / min. It supplied to the washing bottle 21 and aerated, and the gas absorbed in the absorption liquid was desorbed.
The amount of gas recovered by this operation was 170 liters, the hydrogen sulfide concentration was 155 ppm, and the carbon dioxide concentration was 0.07%.

As shown in FIG. 3, the gas obtained in the hydrogen sulfide gas separation step was sent to the washing bottle 21 by the air pump 22 and dissolved in 200 ml of a 0.1 mol / liter sodium hydroxide solution in the washing bottle.
The gas obtained in the hydrogen sulfide gas separation step for a total of 18 times was absorbed in the sodium hydroxide solution to obtain 200 ml of a 0.09 mol / liter hydrogen sulfide solution.

An apparatus for conducting an experiment of hydrogen generation by treating hydrogen sulfide with a photocatalyst used a closed electrolysis cell 11a as shown in FIG. In this apparatus, the anode side and the cathode side are separated by a cation exchange membrane 3, and the photocatalyst electrode 1 is immersed on the anode side and filled with a 0.09 mol / liter hydrogen sulfide solution prepared in a hydrogen sulfide dissolution process. Was immersed in a metal electrode 2 and filled with a 0.10 mol / liter sulfuric acid solution.
Reference numeral 8 denotes an Xe irradiation lamp for light irradiation, and reference numeral 4 denotes a conductive wire for electrically connecting the photocatalytic electrode 1 and the metal electrode 2.
The photocatalytic electrode 1 was used by fixing cadmium sulfide on a titanium plate according to the method disclosed in Japanese Patent Application Laid-Open No. 2003-181297, and manufacturing the electrode with a size of 100 mm × 100 mm.
On the other hand, although the metal electrode 2 used the electrode which coat | covered platinum on the titanium net | network, the electrode size was 80 mm x 120 mm.

The conducting wire 4 connecting the photocatalyst electrode 1 and the metal electrode 2 was electrically connected using a copper wire.
The container for electrolysis cell (photocatalytic reaction cell) 11a was prepared using an acrylic resin.
Each capacity of one photocatalyst electrode tank and two metal electrode tanks is 200 ml.
When the apparatus having the configuration described above was used and xenon light was irradiated from a xenon irradiation lamp, the amount of hydrogen generation increased substantially in proportion to the irradiation time. The hydrogen generation amount was measured 10 minutes after the start of the light irradiation, and the hydrogen generation amount from the measurement start to 1 hour later was 10.7 ml.
Note that the xenon irradiation lamp 8 is used as a light source in order to quantitatively conduct experiments, and it goes without saying that sunlight can be used practically.

Example 3
As shown in FIG. 6, the apparatus of the second embodiment that conducts the hydrogen generation experiment by treating hydrogen sulfide with a photocatalyst is sulfided so that the HS ^- concentration is 0.1M and the OH ^- concentration is 1M. It installed so that the photoelectrochemical cell 34 which is a 2nd liquid tank might be immersed in the cell 11 for electrolysis which is the 1st liquid tank which accommodated the process liquid which melt | dissolved hydrogen in the sodium hydroxide aqueous solution. Is.

In this photoelectrochemical cell 34, one of the partition materials is formed on the outer surface of a titanium plate as the conductive substrate 33, and cadmium sulfide as the photocatalyst 31 is in accordance with the method disclosed in Japanese Patent Laid-Open No. 2003-181297. The photocatalyst electrode 1 having an electrode size of 100 mm × 100 mm is formed, and platinum as the metal layer 32 is coated on the inner surface of the titanium substrate opposite to the photocatalyst layer by electroplating. Electrode 2 was formed.
The other opposite surface of the partition wall is composed of a cation exchange membrane 3 to form a closed photoelectrochemical cell 34, and sulfuric acid with a concentration of 0.5M as an acidic solution is supplied to the upper portion of the cell 34. -An acrylic resin pipe to be circulated was attached.

The cell 11 for electrolysis which is a 1st liquid tank was comprised with the transparent acrylic resin material. Further, light was irradiated from the outside of the electrolysis cell 11 by a light irradiation Xe irradiation lamp (not shown) so that the light irradiation area of the photocatalyst layer 31 was 15.9 cm ² and the light irradiation surface intensity was 15.1 W. .
The capacity of the electrolysis cell 11 is 1750 ml, and the capacity of the photoelectrochemical cell 34 is 175 ml.

When the apparatus having the above-described configuration was used and xenon light was irradiated from the xenon irradiation lamp, the amount of hydrogen generation increased substantially in proportion to the irradiation time as shown in FIG. The amount of hydrogen generation was measured 30 minutes after the start of light irradiation, and the amount of hydrogen generation from the start of measurement to 6 hours later was 53.1 ml.
In addition, the photocurrent value between the photocatalyst (CdS) layer 31 (photocatalyst electrode 1) and the metal (Pt) layer 32 (metal electrode 2) during the photocatalytic reaction (photoirradiation) is constant at about 23 mA, a stable photocatalytic reaction, It can be seen that hydrogen sulfide treatment and hydrogen production were performed.
The reason why the xenon irradiation lamp (not shown) is used as the light source is to perform the experiment quantitatively, and it goes without saying that sunlight can be used as the light source practically.

  The hydrogen sulfide treatment method, the hydrogen production method and the photocatalytic reaction apparatus of the present invention are a chemical industry such as ammonia or methanol production process requiring hydrogen, sulfuric acid or insecticide production industry requiring sulfur, and It has very promising applications in the chemical industry for producing or treating natural gas, various industrial gases and petroleum for treating hydrogen sulfide generated in the desulfurization process.

BRIEF DESCRIPTION OF THE DRAWINGS It is a principle schematic explanatory drawing of the apparatus used for the process of hydrogen sulfide and production of hydrogen of one Embodiment of this invention. It is the schematic explaining the structure of the apparatus used for Example 1 of this invention. It is the schematic of the apparatus and instrument used when blowing the gas containing hydrogen sulfide and a carbon dioxide in a methyldiethanolamine solution. It is the schematic of the apparatus and instrument used for the removal | desorption of this hydrogen sulfide from the methyldiethanolamine solution which absorbed and dissolved hydrogen sulfide. It is the schematic explaining the structure of the apparatus used for the photocatalytic reaction of Example 2 of this invention. It is the schematic explaining the structure of the apparatus used for another embodiment of the photocatalytic reaction apparatus of this invention, and the photocatalytic reaction of Example 3. FIG. It is a graph which shows the relationship with the reaction time of the amount of hydrogen generation in the photocatalytic reaction of Example 3, and the photocurrent value between electrodes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photocatalyst electrode 2 Platinum electrode 3 Cation exchange membrane 4 Conductor 5 Acrylic resin pipe 6 Transparent vinyl chloride resin pipe 7 Hard vinyl chloride resin pipe 8 Xe irradiation lamp 11 Electrolysis cell 21 Washing bottle 22 Air pump 23 Heating means 24 Cooling means 31 Photocatalyst layer 32 Metal layer 33 Conductive plate 34 Photoelectrochemical cell

Claims (15)

  A liquid tank having a photocatalyst electrode composed of at least a photocatalyst and a liquid tank having a metal electrode are separated by a cation exchange membrane, and the liquid tank having the photocatalyst electrode contains a liquid containing hydrogen sulfide. A method for treating hydrogen sulfide in which a metal electrode is electrically connected and the photocatalyst is exposed to light.   The method for treating hydrogen sulfide according to claim 1, wherein the liquid stored in the liquid tank having the metal electrode is an acidic solution.   The method for treating hydrogen sulfide according to claim 1, wherein the photocatalyst contains a metal sulfide.   The method for treating hydrogen sulfide according to claim 1, wherein the photocatalyst is a fine particle having a layered nanocapsule structure.   The method for treating hydrogen sulfide according to claim 1, wherein the liquid containing hydrogen sulfide is obtained by blowing hydrogen sulfide gas into an alkaline liquid and dissolving it.   6. The hydrogen sulfide gas according to claim 5, wherein a gas containing hydrogen sulfide and carbon dioxide is blown into a methyldiethanolamine solution, and then the methyldiethanolamine solution is heated to a temperature higher than normal temperature and air is blown into and discharged. Treatment method of hydrogen sulfide.   A liquid tank having a photocatalyst electrode composed of at least a photocatalyst and a liquid tank having a metal electrode are separated by a cation exchange membrane, and the liquid tank having the photocatalyst electrode contains a liquid containing hydrogen sulfide or an organic substance. And the metal electrode are electrically connected, and the photocatalyst is exposed to light.   The method for producing hydrogen according to claim 7, wherein the liquid stored in the liquid tank having the metal electrode is an acidic solution.   The method for producing hydrogen according to claim 7, wherein the photocatalyst contains a metal sulfide.   The method for producing hydrogen according to claim 7, wherein the photocatalyst is a fine particle having a layered nanocapsule structure.   The method for producing hydrogen according to claim 7, wherein the liquid containing hydrogen sulfide is obtained by blowing hydrogen sulfide gas into an alkaline liquid and dissolving it.   12. The hydrogen sulfide gas according to claim 11, wherein the gas containing hydrogen sulfide and carbon dioxide is blown into a methyldiethanolamine solution, and then the methyldiethanolamine solution is heated to a temperature higher than room temperature and air is blown into and discharged. A method for producing hydrogen. A first liquid tank having a photocatalyst electrode composed of at least a photocatalyst and containing a liquid containing hydrogen sulfide;
A second liquid tank having a metal electrode,
The first liquid tank and the second liquid tank are separated by a cation exchange membrane,
The photocatalytic electrode and the metal electrode are electrically connected,
A photocatalytic reaction device characterized in that the photocatalytic electrode can be irradiated with light. A first liquid tank containing a liquid containing hydrogen sulfide;
A second liquid tank provided in the first liquid tank;
One part of the partition material of the second liquid tank is composed of a member in which a photocatalyst layer is formed on one surface of a conductive plate and a metal layer is formed on the opposite surface, and the side having the photocatalyst layer is The outer side is configured so that the side having the metal layer is the inner side,
Another part of the partition material of the second liquid tank is composed of a cation exchange membrane,
A photocatalytic reaction device configured to allow light irradiation to the photocatalyst layer.   The photocatalytic reaction device according to claim 13 or 14, further comprising means for supplying or circulating an acidic solution to the second liquid tank.

Images