JP2006263729A - Photocatalytic reaction apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for removing harmful substances efficiently and stably for a long period by utilizing a relation of a photocatalyst and a discharge light from a three-dimensional discharge electrode discharging effectively and stably. <P>SOLUTION: A photocatalytic reaction apparatus 1 has at least one photocatalyst module 6 supporting the photocatalyst on a ceramic substrate of a three-dimensional network, and a honeycomb electrode 5. The honeycomb electrode is a three-dimensional electrode, and is formed in a honeycomb shape with conductive foil. The shape as viewed from the front and the back faces is honeycomb, and gas containing the harmful substances can pass through from the front face to the back face direction. The sides of the electrode are covered with a conductive outer frame 4. The honeycomb electrode has a predetermined depth from the front face of the electrode to the back face direction, and is constituted by a pair of electrode bodies 3 holding the photocatalyst module 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention can efficiently and stably remove a substance by utilizing the relationship between discharge light (ultraviolet light) from a three-dimensional discharge electrode that effectively and stably discharges and a photocatalyst. The present invention relates to a photocatalytic reaction device.

  It is a well-known fact that environmental pollution caused by harmful substances such as dioxins and NOx in the atmosphere and harmful substances in sewage is a social problem, and research on methods to effectively remove these harmful substances・ Development is active. In recent years, countermeasures against harmful substances in sealed spaces such as ethylene gas, which is a septic gas in refrigerators, formaldehyde, toluene, xylene, paradichlorobenzene, which is the cause of sick house syndrome, and tobacco odors in rooms and cars have become a problem. ing.

  Conventionally, as an example of a method for removing the harmful substances described above, a method using a discharge treatment device using discharge or a method using a photocatalytic reaction device using a photocatalyst is known.

  FIG. 15 shows an example of a conventional photocatalytic reaction device.

As shown in FIG. 15, the photocatalytic reaction device 101 is housed in a housing 102, and includes a photocatalyst 103 that supports titanium oxide, a pair of thin film electrodes 104 that are arranged to face each other with the photocatalyst interposed therebetween, and an electrode 104. And a high voltage power supply unit 105 that applies a high voltage to the electrode 104, a high voltage applied to the electrode 104 generates a discharge between the electrodes 104, and the photocatalyst 103 (titanium oxide TiO ₂ ) is activated by the ultraviolet rays generated by the discharge. To remove harmful substances contained in the gas. At this time, the photocatalyst 103 activated by the ultraviolet rays generated by the discharge of the electrode 104 generates a hydroxy radical (.OH) and a superoxide anion (.O ₂ ⁻ ), of which the hydroxy radical has a strong oxidizing power, The molecular bond of each substance can be broken. Using the oxidizing power of this hydroxy radical, harmful substances are removed by chemical reaction.

  However, the conventional photocatalytic reaction device using the discharge light of the electrode has the following problems.

  Since the electrode 104 that has been used in the past is thin, the electrode is corroded against corrosive gases such as hydrogen sulfide, sulfurous acid, nitrous acid, chlorine, and ammonia among harmful substances, Durability was poor.

  In addition, once the electrode is corroded, discharge is not performed in the corroded portion, and uniform discharge light cannot be generated in the entire electrode. If the corroded part spreads, the part where the conduction is cut off is generated, and it was possible to irradiate the discharge light to activate the photocatalyst in some part of the electrode, but in the other part the photocatalyst was activated As a result, “unevenness” such that it was impossible to irradiate the discharge light to such an extent that the expected catalytic effect could not be obtained.

  Further, since both electrodes 104 are in the form of a thin film, there was instability with respect to installation. In order to obtain a catalytic effect efficiently, it is necessary to keep both electrodes 104 in a parallel state. However, the mounting method and the state of harmful substances flowing in, for example, when the flow velocity is very high or when there is a lot of dust or dust In the case where it is included, there are cases where the installation location is displaced, the electrode is deformed or broken, and the photocatalyst cannot be irradiated stably with the discharge light.

  The present invention has been made in view of the above circumstances, and utilizes the relationship between discharge light from a three-dimensional discharge electrode that effectively and stably discharges and a photocatalyst to be efficiently and stably harmful. An object of the present invention is to provide a photocatalytic reaction apparatus capable of removing substances.

  In order to achieve the above object, the present invention relates to a photocatalytic reaction apparatus that performs deodorization and gas purification by a photocatalytic reaction, at least one photocatalytic module having a photocatalyst supported on a ceramic substrate having a three-dimensional network structure, and the photocatalytic module. Each of the pair of electrodes sandwiched is a three-dimensional shape, and the front and back shapes are formed in a honeycomb shape, a lattice shape, or a mesh shape by conductive foil, and have a predetermined depth width from the front to the back It is comprised from the main body and the discharge electrode part which is a discharge electrode comprised from the electroconductive outer frame which covers the side surface of the said electrode main body, It is characterized by the above-mentioned.

  The photocatalytic reaction apparatus according to the present invention improves the corrosion resistance, and can remove harmful substances efficiently and stably.

  The photocatalytic reaction device according to the present invention will be described with reference to FIGS.

<First Embodiment>
First, the minimum structural unit of the photocatalytic reaction device of the present invention will be described with reference to FIG. 1 and FIG. FIG. 2 is a schematic diagram of the photocatalytic reaction device of FIG.

  In FIG. 1, a photocatalytic reaction device 1 (photocatalytic reaction device 1A in FIG. 2) is composed of a unit structure 2 and a casing 7 for housing it. The casing 7 has a cylindrical structure, and has an inlet and an outlet so that a gas containing harmful substances can pass therethrough. The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and the pair of honeycomb electrodes 5 is connected to a high voltage power supply unit (not shown) (high voltage power supply unit 8 in FIG. 2). .

  The honeycomb electrode 5 is a three-dimensional electrode which is formed of a conductive foil and is formed into a honeycomb shape, and is composed of an electrode body 3 and a conductive outer frame 4 having a honeycomb shape when viewed from the front and the back. Moreover, it penetrates in a honeycomb shape from the front to the depth direction so that a gas containing harmful substances can pass through. The side surface of the electrode body 3 is covered with a conductive outer frame 4 and has a predetermined depth width from the front side to the back side of the electrode.

  In FIG. 2, the honeycomb electrode 5 is discharged by electric power supplied from the high voltage power supply unit 8. The electrode body 3 and the conductive outer frame 4 constituting the honeycomb electrode 5 are made of stainless steel that is resistant to corrosive gases such as hydrogen sulfide.

  Of the discharge light generated by the discharge, ultraviolet light having a wavelength of 185 nm generates ozone from oxygen in the atmosphere. Ozone has a deodorizing, decolorizing, sterilizing and sterilizing action and can decompose and remove harmful substances such as hydrogen sulfide and ammonia, but at the same time, the metal of the electrode is oxidized due to its strong oxidizing power.

  In addition, corrosive gases such as hydrogen sulfide, sulfurous acid, nitrous acid, chlorine, ammonia, etc. among toxic substances will corrode the electrode, so the metal used for the electrode may be corrosion resistant or corrosion resistant. It is necessary to select one that has been coated.

  The materials used for the electrode body 3 and the conductive outer frame 4 include, in addition to stainless steel, metals such as aluminum and copper that have been subjected to coating treatment, and metals (alloys) that have strong corrosion resistance such as hastelloy, platinum, and gold. Is raised.

  In the case of the honeycomb electrode 5, the cell size is required to be 5 mm or more, and the foil thickness is required to be 1 mm or less, preferably 0.1 to 0.2 mm (the reason will be described later).

The photocatalyst module 6 sandwiched between the honeycomb electrodes 5 is a ceramic substrate having a three-dimensional network structure, and carries fine particles of semiconductor TiO ₂ having a photocatalytic action on the substrate surface. The thickness of the photocatalyst module 6 is required to be 15 mm or less (the reason will be described later).

Various kinds of semiconductor fine particles having a photocatalytic action can be mentioned. A typical semiconductor with photocatalytic action is titanium oxide TiO ₂ (anatase type, rutile type, brookite type), but other metal oxides such as SrTiO ₃ , ZnO, BaTiO ₃ , V ₂ O ₅ , SnO _2, etc. Examples include semiconductors, single semiconductors such as Si, GaAs, CdS, and ZnS, and compound semiconductors.

  Various types of the high-voltage power supply unit 8 that supplies power to the honeycomb electrode 5 are conceivable depending on the installation environment. A DC power supply, a pulse power supply that outputs a short pulse with a duty ratio of 0.5 or less, an AC power supply with a frequency of 10 kHz or more, and the like are included. Further, a function of superimposing a direct current bias corresponding to 50 to 90% of the peak value or intermittent operation may be added to each type of high-voltage power supply.

  In the present invention, when a DC power source is used for the high-voltage power source unit 8, the configuration of the power source unit is simple, and the apparatus cost can be kept low. In the case of direct current discharge, the operation sound accompanying the discharge is extremely small, which is preferable when a quiet operation is required.

  In addition, when a pulse power supply is used, a large amount of energy can be easily input compared to a DC operation, and the apparatus can be downsized. The power supply unit configuration is simple, and the apparatus cost can be kept low. In addition, it is easy to increase the input energy as compared with the direct current discharge, which is preferable when a low-priced and medium-scale apparatus is configured.

  In addition, when a high-frequency AC power source having a frequency of 10 kHz or higher is used, the input energy can be increased with an increase in the operating frequency, and a large amount of energy can be input. This method is effective when dealing with large-volume deodorizing treatments and high-concentration objects.

  Further, when a DC bias is superimposed, the pulse voltage can be reduced compared to the case where a pulse power supply or the like is used alone, and the power supply device can be reduced in size. In addition, since the number of the surviving electrons that cause the discharge is stabilized, variations in the spark transition voltage are reduced, and a stable operation can be ensured.

  In the photocatalytic reaction apparatus of FIGS. 1 to 7, when a pulse power supply or an AC power supply is used, the discharge input energy per pulse or per cycle is uniquely determined by discharge part parameters such as gas composition, electrode shape, and electrode interval. Will be fixed.

  If the discharge input energy per pulse or cycle is E [J] and the repetition period is r [pps] or [Hz], the input power is defined as E × r [W]. Or in order to make it constant regardless of the period, intermittent operation is performed.

  The ratio of operation to non-operation (modulation degree) with respect to intermittent operation is as follows: if the input power required is P, the input energy per pulse (cycle) is E, and the repetition number is F, the modulation degree is P / (E × F).

If the input power is 10 [W], the input energy per pulse is 50 [mJ], and the number of repetitions is 20 [kHz], the modulation factor is
[Equation 1]
10 / (50 × 10 ⁻³ × 20 × 10 ³ ) = 0.01
It becomes. In this case, a mode that operates only for 10 milliseconds per second is required.

  This operation mode is not limited to “10 milliseconds operation per second”, and may be, for example, “20 milliseconds operation once every 2 seconds” or “5 milliseconds operation twice per second”.

  In addition, even when a DC power supply is used, the input power is almost uniquely determined by the discharge unit parameters. Therefore, by performing intermittent operation, it is possible to operate with lower power than in the case of continuous operation without changing the voltage. .

  In the configuration shown in FIG. 1 (FIG. 2), when a high voltage is applied from the high voltage power source 8 to the honeycomb electrode 5, the honeycomb electrode 5 starts to discharge, and the discharge light (ultraviolet rays) generated by this discharge is the photocatalyst module. 6 is evenly irradiated to activate the photocatalyst. This activated photocatalyst generates chemically reactive hydroxyl radicals (.OH), and ozone is generated by the discharge light. By reacting with these active chemical species of hydroxyl radicals and ozone, harmful substances flowing into the unit structure 2 are decomposed and removed.

  In this first embodiment, each of the pair of honeycomb electrodes 5 is covered with the conductive outer frame 4 and has a depth width, so that the corrosion resistance is improved as compared with the conventional thin film electrode. There is an effect that uniform discharge light can be obtained over a long period of time.

  In addition, since sufficient mechanical accuracy and strength can be ensured, the distance between the electrodes can be kept constant over a long period of time, so that the discharge light can be uniformly and effectively irradiated onto the photocatalyst module 6. The material decomposition performance higher than that of the electrode can be obtained efficiently and stably for a long time.

  Furthermore, ozone generated by the discharge is decomposed and removed by chemically reacting with harmful substances that could not be processed by the photocatalyst module 6. The ozone oxidizing power promotes the decomposition efficiency of the photocatalytic reaction device.

  In the case where the electrode has a polarity as in the case where the high voltage power supply unit 8 is a DC power supply, the inflow direction of the harmful substance may be from either the positive electrode side or the negative electrode side, and the same effect can be obtained.

  Further, by intermittently operating the high-frequency AC power supply, it is possible to efficiently supply power, and discharge can be performed with lower power than in the case of continuous operation.

<Second Embodiment>
FIG. 3 shows a structure in which a plurality of unit structures 2 shown in FIG. 1 (FIG. 2) are stacked.

  The photocatalytic reaction device 1B shown in FIG. 3 includes four unit structures 2, a housing 7 for housing them, and a high-voltage power supply unit 8. The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and the honeycomb electrodes 5 are each connected to a high-voltage power supply unit 8.

  In this embodiment, the four unit structure bodies 2 are arranged so that adjacent electrodes are shared between the unit structure bodies 2. By alternately arranging the electrodes, both electrode surfaces emit light, and discharge light can be obtained effectively.

  Note that the configuration of the honeycomb electrode 5, the structure and the material used for the electrode, the structure of the photocatalyst module 6, the material of the semiconductor fine particles used for the module, and the high-voltage power supply unit 8 are the same as those in the first embodiment, and the description thereof is omitted. To do.

  3, when a high voltage is applied to the honeycomb electrode 5 from the high-voltage power supply unit 8, the honeycomb electrode 5 starts to discharge, and the discharge light (ultraviolet rays) generated by this discharge is uniformly applied to the photocatalyst module 6. Irradiated to activate the photocatalyst. This activated photocatalyst generates chemically reactive hydroxyl radicals (.OH), and ozone is generated by the discharge light. By reacting with these active chemical species of hydroxyl radicals and ozone, harmful substances flowing into the unit structure 2 are decomposed and removed.

  In the second embodiment, the honeycomb electrode 5 has the same corrosion resistance, mechanical accuracy, and strength as the first embodiment, and the same effect is obtained, and by laminating four unit structures, As compared with the first embodiment, there is an effect that the material decomposition performance four times as high as that of the first embodiment can be obtained.

  In addition, the amount of ozone generated by the discharge increases as the number of electrodes increases compared to the first embodiment, so that the decomposition efficiency of harmful substances due to the oxidizing power of ozone is further promoted compared to the first embodiment. There is an effect.

<Third Embodiment>
FIG. 4 shows an ozone decomposition catalyst 9 added to the photocatalytic reaction apparatus 1 (1A) of FIG. 1 (FIG. 2).

  The photocatalytic reaction device 1 </ b> C in FIG. 4 includes a housing 7 that houses the unit structure 2 and the ozone decomposition catalyst 9, and a high-voltage power supply unit 8.

  The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and the pair of honeycomb electrodes 5 is connected to a high voltage power supply unit 8. The ozone decomposition catalyst 9 is disposed downstream of the unit structure 2 with respect to the gas inflow direction.

  Note that the configuration of the honeycomb electrode 5, the structure and the material used for the electrode, the structure of the photocatalyst module 6, the material of the semiconductor fine particles used for the module, and the high-voltage power supply unit 8 are the same as those in the first embodiment, and the description thereof is omitted. To do.

  In the first embodiment and the second embodiment, ozone generated by the discharge light decomposes and removes harmful substances with its oxidizing power, but ozone that has not reacted with the harmful substances is released as it is. However, ozone is usually harmful to the human body if released into the atmosphere as it is, so it must be decomposed in some cases. The ozone decomposition catalyst 9 decomposes such unreacted ozone into harmless oxygen.

  There are various methods for decomposing ozone, depending on the conditions of use. Typical examples include activated carbon adsorption decomposition method, thermal decomposition method, catalytic decomposition method, water washing method, chemical solution washing method (alkali washing method). And chemical solution reduction method.

  4, when a high voltage is applied to the honeycomb electrode 5 from the high-voltage power supply unit 8, the honeycomb electrode 5 starts to discharge, and the discharge light (ultraviolet rays) generated by this discharge is uniformly applied to the photocatalyst module 6. Irradiated to activate the photocatalyst. This activated photocatalyst generates chemically reactive hydroxyl radicals (.OH), and ozone is generated by the discharge light. By reacting with these active chemical species of hydroxyl radicals and ozone, harmful substances flowing into the unit structure 2 are decomposed and removed. Further, unreacted ozone is decomposed into harmless oxygen by the ozone decomposition catalyst 9.

  In the third embodiment, the same material decomposition performance as in the first embodiment can be obtained. Furthermore, by decomposing ozone that has not reacted with harmful substances by the ozone decomposition catalyst 9, there is an effect that ozone harmful to the human body can be prevented from being released into the atmosphere.

  In the present embodiment, one ozone decomposition catalyst 9 is installed at the most downstream portion, but the arrangement position and number are not particularly limited as long as exhaust ozone can be efficiently removed.

<Fourth Embodiment>
FIG. 5 shows an ozone decomposition catalyst 9 added to the photocatalytic reaction device 1B of FIG.

  The photocatalytic reaction device 1D shown in FIG. 5 includes a casing 7 that houses four unit structures 2 and an ozone decomposition catalyst 9, and a high-voltage power supply unit 8. The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and the honeycomb electrodes 5 are each connected to a high-voltage power supply unit 8. The ozone decomposition catalyst 9 is disposed downstream of the unit structure 2 with respect to the gas inflow direction.

  The structure of the unit structure 2, the structure of the honeycomb electrode 5, the structure and the material used for the electrode, the structure of the photocatalyst module 6, the material of the semiconductor fine particles used for the module, and the high-voltage power supply unit 8 are the same as those in the second embodiment. The description is omitted because it is similar.

  In the configuration shown in FIG. 5, when a high voltage is applied to the honeycomb electrode 5 from the high voltage power supply unit 8, the honeycomb electrode 5 starts to discharge, and the discharge light (ultraviolet rays) generated by this discharge is uniformly distributed to the photocatalyst module 6. Irradiated to activate the photocatalyst. This activated photocatalyst generates chemically reactive hydroxyl radicals (.OH), and ozone is generated by the discharge light. By reacting with these active chemical species of hydroxyl radicals and ozone, harmful substances flowing into the unit structure 2 are decomposed and removed. Further, unreacted ozone is decomposed into harmless oxygen by the ozone decomposition catalyst 9.

  In the fourth embodiment, the same material decomposition performance as in the second embodiment can be obtained. Furthermore, by decomposing ozone that has not reacted with harmful substances by the ozone decomposition catalyst 9, there is an effect that ozone harmful to the human body can be prevented from being released into the atmosphere.

  In the present embodiment, one ozone decomposition catalyst 9 is installed at the most downstream portion, but the arrangement position and number are not particularly limited as long as exhaust ozone can be efficiently removed.

<Fifth Embodiment>
FIG. 6 is obtained by adding a blower 10 to the photocatalytic reaction device 1 (1A) of FIG. 1 (FIG. 2).

  The photocatalytic reaction device 1E of FIG. 6 includes a unit structure 2, a blower 10, a housing 7 that houses them, and a high-voltage power supply unit 8. The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and the pair of honeycomb electrodes 5 is connected to a high voltage power supply unit 8.

  The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and the pair of honeycomb electrodes 5 is connected to a high voltage power supply unit 8. Moreover, the air blower 10 is installed in the gas inflow part.

  Note that the configuration of the honeycomb electrode 5, the structure and the material used for the electrode, the structure of the photocatalyst module 6, the material of the semiconductor fine particles used for the module, and the high-voltage power supply unit 8 are the same as those in the first embodiment, and the description thereof is omitted. To do.

  The blower 10 is used when the flow rate of a gas containing a harmful substance is slow or when forced circulation of the airflow is required. When gas is circulated by natural convection, convection may be stopped depending on the situation. At that time, convection is forcibly caused by using the blower 10 to ensure a certain flow velocity.

  The installation location can be a gas inflow part or a gas exhaust part, but is not limited to the entrance / exit of the apparatus. When a plurality of unit structures 2 are stacked, they may be installed between the unit structures, between the discharge electrode and the photocatalyst module 6 or before the ozone decomposition catalyst depending on the installation environment of the apparatus.

  In the configuration shown in FIG. 6, the fluid containing harmful substances is forcibly sent to the housing 7 by the blower 10. When a high voltage is applied to the honeycomb electrode 5 from the high-voltage power supply unit 8, the honeycomb electrode 5 starts to discharge, and the discharge light (ultraviolet rays) generated by this discharge is uniformly irradiated to the photocatalyst module 6 to activate the photocatalyst. Make it. This activated photocatalyst generates chemically reactive hydroxyl radicals (.OH), and ozone is generated by the discharge light. By reacting with these active chemical species of hydroxyl radicals and ozone, harmful substances flowing into the unit structure 2 are decomposed and removed.

  In the fifth embodiment, the same material decomposition performance as in the first embodiment can be obtained. Furthermore, by using a blower, it is possible to ensure a certain flow rate, to obtain a certain processing capacity intermittently, and to maintain the substance decomposition performance of the photocatalytic reaction device 1E of this embodiment for a long period of time. There is an effect.

<Sixth Embodiment>
FIG. 7 is obtained by adding a filter 11 to the photocatalytic reaction device 1E of FIG.

  The photocatalytic reaction device 1F in FIG. 7 includes a unit structure 2, a blower 10, a filter 11, a housing 7 that houses them, and a high-voltage power supply unit 8. The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and is connected to a high voltage power supply unit 8.

  The unit structure 2 is composed of a pair of honeycomb electrodes 5 and a photocatalyst module 6 sandwiched between them, and the pair of honeycomb electrodes 5 is connected to a high voltage power supply unit 8. The blower 10 is installed in the gas inflow portion, and the filter 11 is installed on the inflow side of the blower 10.

  Note that the configuration of the honeycomb electrode 5, the structure and the material used for the electrode, the structure of the photocatalyst module 6, the material of the semiconductor fine particles used for the module, and the high-voltage power supply unit 8 are the same as those in the first embodiment, and the description thereof is omitted. To do.

  When used in an environment with a lot of dust or dust, the photocatalyst module 6 or the honeycomb electrode 5 may be clogged or damaged. Covering electrodes and photocatalysts such as dust and dust, those that degrade their performance, those that impede their functions, and those that cannot be decomposed in this embodiment are first removed using the filter 11, and stable and stable material decomposition performance Secure.

  In the configuration shown in FIG. 7, the fluid containing a harmful substance from which dust or dust has been removed by the filter 11 is forcibly sent to the housing 7 by the blower 10. When a high voltage is applied to the honeycomb electrode 5 from the high-voltage power supply unit 8, the honeycomb electrode 5 starts to discharge, and the discharge light (ultraviolet rays) generated by this discharge is uniformly irradiated to the photocatalyst module 6 to activate the photocatalyst. Make it. This activated photocatalyst generates chemically reactive hydroxyl radicals (.OH), and ozone is generated by the discharge light. By reacting with these active chemical species of hydroxyl radicals and ozone, harmful substances flowing into the unit structure 2 are decomposed and removed.

  In the sixth embodiment, the same material decomposition performance as in the first embodiment can be obtained. Further, by removing in advance harmful substances that cannot be decomposed by the present invention using the filter 11, it becomes possible to stably ensure the substance decomposition performance, and the substance decomposition performance of the photocatalytic reaction device 1F of the present embodiment is prolonged. There is an effect of maintaining the period.

<Other configuration examples>
So far, examples using honeycomb electrodes have been shown, but the present invention is not limited to these examples.

  In addition, when using a honeycomb electrode, a grid electrode, or a mesh electrode, it is not necessary to use the same material for the positive electrode and the negative electrode. One is a honeycomb electrode, and the other is a grid electrode. Combinations are also possible.

  Furthermore, it is also considered as a usage method to use a thing with different cell sizes for the positive electrode and the negative electrode. For example, a combination of a honeycomb electrode having a cell size of 5 mm and a grid electrode having a cell size of 10 mm can be used for the positive electrode.

  On the other hand, in addition to the filter 11 of FIG. 7, it is also conceivable to use a combination of substances that remove specific substances such as other types of catalysts and adsorbents. When a specific substance is removed by another catalyst or adsorbent and the remaining substance is decomposed and removed by the present invention, or when a remaining substance that could not be decomposed and removed by the present invention is removed by another catalyst or adsorbent However, it can be considered as a method of use. This is effective as means for improving the performance of the present invention.

  As an application of the present invention, industrial exhaust gas treatment machines, air purifiers, and the like are assumed in the photocatalytic reaction apparatus of FIGS. Moreover, in the photocatalytic reaction apparatus of FIG.4 and FIG.5, it is assumed that it integrates in an indoor air conditioner, a vehicle-mounted air conditioner, a cleaner, a refrigerator, etc. Furthermore, in the case of FIG. 6, it is assumed that it is incorporated in a natural convection refrigerator or the like, and in the case of FIG. 7, an indoor air purifier (used in this case with an ozone decomposition catalyst), a smoke separator, or the like is provided. is assumed.

<Description of honeycomb electrode>
Here, the results of tests conducted to verify the characteristics of the discharge electrode, particularly the honeycomb electrode, used in the photocatalytic reaction device of the present invention will be described. The comparative test was performed using the unit structure 2 shown in FIG.

<Performance comparison with conventional products>
(1) Comparison of light emission intensity due to difference in electrode structure In order to obtain high material decomposition performance using a photocatalyst, a light source that generates strong discharge light (ultraviolet light, wavelength 380 nm or less) is necessary to activate the photocatalyst. is there. It is known that discharge is more likely to occur as the electric field is stronger, and the electric field greatly depends on the shape of the electrode.

  FIG. 8 compares the emission intensity of discharge light in the same area using the same power source (same input energy). As can be seen from FIG. 8, the product of the present invention generated strong discharge light about 1.5 to 2 times that of the conventional type. In other words, a material decomposition performance that is about 1.5 to 2 times higher can be obtained with the same power.

(2) Comparison of emission intensity distribution due to difference in electrode structure FIGS. 9 and 10 show the emission intensity of discharge light in the same area as an in-plane distribution using the same power source (same input energy). .

  In FIG. 9, the light emission intensity necessary and sufficient for activating the photocatalyst was obtained in the peripheral part of the electrode, but the light emission intensity sufficient to activate the photocatalyst was not obtained in the central part. Because of such variations, a sufficient catalytic effect could not be obtained.

  On the other hand, in FIG. 10, uniform light emission intensity was obtained over the entire surface of the electrode. Therefore, compared with the conventional product, a stable catalytic effect can be expected, and high material decomposition performance can be obtained.

<About cell shape>
(1) Performance comparison due to difference in cell size When honeycomb-shaped electrodes are used, the emission intensity of the discharge light varies depending on the difference in honeycomb cell size 12 (mesh size (FIG. 11)). FIG. 12 shows the relationship between the cell size 12 and the light emission intensity. When the cell size 12 was 5 mm or more, the emission intensity of the discharge light increased rapidly, and high material decomposition performance could be obtained.

(2) Performance comparison due to difference in foil thickness When the honeycomb electrode 5 is used, the emission intensity of the discharge light varies depending on the difference in the thickness of the metal foil constituting the honeycomb. FIG. 13 shows the relationship between the foil thickness 13 and the emission intensity. When the foil thickness 13 was 0.1 to 0.2 mm, the intensity of the discharge light increased rapidly, and high material decomposition performance could be obtained.

<Distance of discharge light>
In order to obtain high substance decomposition performance using a photocatalyst, it is necessary to irradiate the catalyst surface uniformly with the discharge light for activating the photocatalyst and to the inside of the photocatalyst. FIG. 14 shows the relationship between the emission intensity and the reach distance when the surface of the photocatalyst module 6 is irradiated with discharge light.

In general, the emission intensity required for the activation of the photocatalyst is 10 ⁻⁶ W / cm ² . As is clear from FIG. 14, it was found that the discharge light enough to activate the photocatalyst did not reach the portion thicker than 15 mm. Therefore, in the configuration of the present invention in which the photocatalyst is sandwiched, the photocatalyst module 6 has a thickness of 15 mm or less, so that high substance decomposition performance can be obtained over the entire photocatalyst.

It is a figure which shows the photocatalyst reaction apparatus comprised from a conductive outer frame, a honeycomb electrode, a photocatalyst module, and the housing | casing which accommodates them. FIG. 2 is a schematic diagram of a photocatalytic reaction device including the photocatalytic reaction device of FIG. 1 and a high-voltage power supply unit. It is a schematic diagram of the photocatalytic reaction device comprised from the unit structure and the high voltage power supply part which were laminated | stacked two or more. It is a schematic diagram of the photocatalytic reaction apparatus comprised from a unit structure, a high voltage power supply part, and an ozone decomposition catalyst. It is a schematic diagram of the photocatalytic reaction apparatus comprised from the unit structure laminated | stacked two or more, the high voltage power supply part, and the ozone decomposition catalyst. It is a schematic diagram of the photocatalytic reaction apparatus comprised from a unit structure, a high voltage power supply part, and a fan. It is a schematic diagram of the photocatalytic reaction device comprised from a unit structure, a high voltage power supply part, a fan, and a filter. It is a figure which shows the difference in the emitted light intensity by the difference in the structure of an electrode. It is a figure which shows distribution of the emitted light intensity of the conventional thin film electrode. It is a figure which shows distribution of the emitted light intensity of a honeycomb electrode. It is explanatory drawing of cell size and foil thickness. It is a figure which shows the relationship between cell size and emitted light intensity. It is a figure which shows the relationship between foil thickness and emitted light intensity. It is a figure which shows the relationship between the reach | attainment distance (thickness of a photocatalyst module) of discharge light, and the emitted light intensity. It is a schematic diagram of the photocatalyst reaction apparatus using the conventional electrode and photocatalyst.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photocatalytic reaction apparatus 2 Unit structure 3 Electrode main body 4 Conductive outer frame 5 Honeycomb electrode 6 Photocatalyst module 7 Case 8 High voltage power supply part 9 Ozone decomposition catalyst 10 Blower 11 Filter 12 Cell size 13 Foil thickness 101 Photocatalytic reaction apparatus 102 Case 103 Photocatalyst 104 Electrode 105 High voltage power supply

Claims (1)

In a device that performs deodorization by photocatalytic reaction and gas purification,
At least one photocatalyst module having a photocatalyst supported on a ceramic substrate having a three-dimensional network structure;
The pair of electrodes sandwiching the photocatalyst module is three-dimensionally formed, and the front and back shapes are formed in a honeycomb shape, a lattice shape, or a mesh shape by conductive foil, and have a predetermined depth from the front to the back. A discharge electrode portion which is a discharge electrode composed of an electrode body having a width and a conductive outer frame covering a side surface of the electrode body;
A photocatalytic reaction device comprising:

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