JPH11207149A - Metal carrying photocatalyst type air purifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain putting a photocatalyst type air purifier into practical use on a domestic/industrial scale with respect to an air purifiers using a photocatalsyt to decompose contaminant particles by remarkably increasing the decomposition efficiency thereof. SOLUTION: In this air purifier, metal carrying photocatalyst fine particles 28 where metal superfine particles 26 of 10 nm or less particle size are carried on photocatalsyt fine particles 24 by 100 or more per photocatalyst fine particle 24 is used, and adsorbing material on whose surface a lot of the metal carrying photocatalyst fine particles 28 are dispersed and fixed is assembled to an excitation light source or a fan. In this way, the purifying efficiency of the photocatalyst type air purifier which has not been put to practical use can be remarkably increased. By manifestation of quantum size effect and high density carrying effect of the metal superfine particles 26, the photocatalyst type air purifier can be put to practical use on a domestic/industrial scale. In this case, decomposable contaminant particles 22 include not only harmful organic material such as tobacco but also organic material unnecessary for environment, hydrogen sulfide, mold, and bacteria such as coli bacillus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air purifier for decomposing contaminant particles in contaminated air with a photocatalyst. More specifically, in order to enhance photocatalytic activity, ultrafine metal particles are supported on photocatalyst fine particles. The present invention relates to a metal-supported photocatalyst type air purifier in which supported photocatalyst fine particles are fixed on the surface of an adsorbent such as a solid adsorbent or an adsorbent fibrous body, and contaminant particles are first adsorbed on the surface of the adsorbent and then decomposed by the metal-supported photocatalyst. .

[0002]

2. Description of the Related Art A typical example of a conventional air purifier using a photocatalyst uses an adsorbent made of a honeycomb-like solid body such as activated carbon or zeolite, as disclosed in a deodorizer of Japanese Patent No. 2574840. In this structure, fine particles of photocatalyst such as titanium dioxide are fixed on the surface of a honeycomb-like solid body in a dispersed state, and the photocatalyst is excited by an excitation light source while passing polluted air through the honeycomb holes. It also discloses an example in which fibrous activated carbon is used as an adsorbent instead of a honeycomb solid body, and photocatalyst fine particles are dispersed and fixed on the surface, and the surface is irradiated with excitation light.

[0003] To explain the operation, when contaminated air passes, contaminant particles are adsorbed on the surface of the honeycomb pores and fibrous activated carbon. Adsorbents such as honeycomb solids and fibrous activated carbon are materials having a myriad of micropores, and are adsorbed by contaminant particles entering these micropores. When excitation light is applied to the surface of a honeycomb solid body or fibrous activated carbon, electron-hole pairs are generated in photocatalytic fine particles near the contaminant particles, and the photocatalytic action of the electrons and holes decomposes the contaminant particles. . The reason why the honeycomb structure is adopted is to increase the contact area with the contaminated air and increase the adsorption performance.

[0004]

The conventional air purifier (deodorizer) has the following serious drawbacks. The biggest disadvantage is that the decomposition efficiency of the photocatalytic substance is relatively low. Even if activated carbon or fibrous activated carbon adsorbs a large amount of contaminants, if the ability to decompose the adsorbed contaminants is low, contaminants that cannot be decomposed will accumulate on the surface of the adsorbent, and eventually the adsorbing power of the adsorbent will increase. Will be exhausted. Replacement of the adsorbent has resulted in a rise in price and has hindered the spread of air purifiers.

The photocatalytic substance used is a simple substance of a metal oxide such as titanium dioxide, tungsten oxide, zinc oxide or a composite thereof. Among them, titanium dioxide has been widely used because of its relatively high decomposition efficiency and high safety. As is known as the Honda-Fujishima effect, the photocatalytic properties of titanium dioxide, such as its ability to decompose organic substances, have been outstanding among oxide semiconductors since its discovery more than 20 years ago. At the beginning of the discovery, research was actively conducted to break down water into hydrogen, and use that hydrogen as a clean fuel instead of gasoline. But,
The study did not progress very well. The reason is that the photocatalytic efficiency of titanium dioxide itself was limited. The same applies to other photocatalyst materials such as tungsten oxide.

The reason is considered as follows. To briefly describe the photocatalytic reaction, when titanium dioxide is irradiated with excitation light such as ultraviolet light, electron-hole pairs are generated inside. The holes act on the OH ⁻ at the surface to generate hydroxyl radicals.
On the other hand, electrons act on O ₂ at the surface to generate O ₂ ⁻ (superoxide anion). This hydroxyl radical and O
₂ ^- degrades attacks the adsorbed contaminants in the direct vicinity. However, it has been found that electrons and holes recombine and disappear inside or on the surface of titanium dioxide before such a decomposition reaction occurs. It goes without saying that if the electrons and holes disappear before generating O ₂ ⁻ or hydroxyl radical, the photocatalytic effect cannot be exerted.

[0007] Therefore, in order to inhibit recombination of electrons and holes, a metal-supported photocatalyst for forming a metal electrode on the surface of titanium dioxide has been developed. The metal electrode has a size of a micron size, and is designed to collect the excited electrons in the metal electrode and separate it from the holes on the titanium dioxide side. When the photocatalytic efficiency of the metal-supported photocatalyst was measured, it was found that the photocatalytic efficiency increased only about 2 to 4 times as compared with the conventional photocatalyst, but it was not in a state that the photocatalytic efficiency increased remarkably.

[0008] The reason that the photocatalytic efficiency did not increase sharply is that the size of the metal electrode remained at the micron size. Since such metal fine particles show the same physical properties as ordinary bulk metal, even if electrons initially collect on the metal,
Concentration to some extent causes the effect of repelling electrons by electrostatic repulsion. Also, when electrons pass through the interface between the metal and titanium dioxide, a certain amount of energy is required to break through the barrier. That is, although it is possible to collect a small amount of electrons, it is difficult to concentrate a large amount of electrons. Furthermore, since the metal fine particles are large in micron size, the number of metal fine particles that can be supported per titanium dioxide fine particle cannot exceed the range of several tens.
That is, the fact that the metal fine particles have a micron size and the supporting density is low are the causes of the peak of the photocatalytic efficiency.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and a metal-supported photocatalyst type air purifier according to the present invention is characterized in that ultrafine metal particles having a particle size of 10 nm or less are converted into photocatalytic fine particles. By using a metal-supported photocatalyst fine particle supported on a substrate, an adsorbent in which a large number of the metal-supported photocatalyst fine particles are dispersed and fixed is provided, and an excitation light source for irradiating the adsorbent with excitation light is provided. The method is characterized by adsorbing contaminant particles therein, irradiating excitation light, and decomposing the adsorbed contaminants by the metal-supported photocatalyst fine particles. Further, the above structure is characterized in that metal-supported photocatalyst fine particles in which 100 or more ultrafine metal particles having a particle size of 10 nm or less are supported per photocatalyst fine particle are used. Further, the present invention proposes an air purifier provided with a fan for forcibly blowing the contaminated air to the adsorbent, and a suction port for taking in the contaminated air and a discharge port for discharging the air.
However, the contaminant particles referred to in the present invention are collectively referred to as the material particles to be purified by the air purifier, and include not only toxic organic substances such as tobacco and formaldehyde, but also non-toxic organic substances unnecessary for the control environment. , Hydrogen sulfide, mold, bacteria, etc.

An air purifier provided with a sensor for detecting contaminants in contaminated air and a drive control circuit for driving and controlling a fan and an excitation light source based on a signal from the sensor is proposed. This sensor and the excitation light source are provided in multiple stages, respectively.
An air purifier is proposed in which the pollutant detection concentration of each sensor is set stepwise, and the lighting time or the number of lighting of the excitation light source is controlled according to the level of the pollution concentration.

Further, an air purifier using an adsorbent fiber as an adsorbent and an air purifier using an adsorbent honeycomb solid body are proposed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies to enhance the photocatalytic function of a metal-supported photocatalyst. About 100
It has been found that it can be increased up to 1000 times or more. Therefore, even when compared with a conventional metal-supported photocatalyst supporting micron-scale metal fine particles, the catalyst efficiency is about 25%.
It can be increased up to about 250 times. This means that the metal is minimized from fine particles to ultrafine particles, that is, the particle size is changed from a micron scale to a nano scale, in other words, the particle size is reduced to 1/10 of a micron scale (about 0.1 μm or more).
This can be achieved by minimizing it to about 1/1000. The average particle diameter of the ultrafine metal particles used in the present invention is 10 nm or less, more preferably 5 nm or less. If it is larger than this, the expression of the quantum size effect, which will be described later, will be small, and the enhancement of the photocatalytic efficiency will not be remarkable.
On the other hand, the lower limit is close to the atomic size, but the closer to the atomic size, the technically difficult to produce ultrafine metal particles.

When photocatalyst fine particles such as titanium dioxide are used as the photocatalytic substance, the number of ultrafine metal particles that can be supported by one photocatalyst fine particle, that is, the loading density of the ultrafine metal particles is an important factor together with the particle diameter. In the present invention, it is possible to support a large number of ultrafine metal particles on one photocatalyst fine particle by using ultrafine metal particles reduced to the nanoscale. According to the inventor's research,
It is desired that the average number of ultrafine metal particles carried per photocatalyst fine particle is set to 100 or more, preferably 200 or more. If the loading density is 100 or more, the photocatalytic efficiency can be significantly increased due to a synergistic effect with the quantum size effect. If the number is 200 or more, a remarkable increase in photocatalytic efficiency can be achieved.

In order to increase the carrying density to 100 or more, it is necessary to devise a supporting method. The method developed by the inventor is called a colloid firing method. That is, an organic metal compound such as an organic metal complex containing a desired metal and a powder of a photocatalytic substance such as titanium dioxide are dispersed in an appropriate known hydrophilic solvent. The organometallic compound forms a hydrophobic colloid,
Many of the metal compound colloid particles adhere to the surface of the photocatalyst powder particles. When the solid residue in the mixture is calcined, the organic matter among the organometallic compounds escapes, and only the metal becomes nanoscale ultrafine particles and is supported on the surface of the photocatalytic fine particles. By adjusting the concentration of the organometallic compound such as an organometallic complex and the photocatalyst powder, a metal-supported photocatalyst having the above-described loading density can be obtained.

The supported ultrafine metal particles may be transition metals. The transition metal element is an element having an incomplete d-shell and having atomic numbers 21 (Sc) to 29 (Cu) and 39 (Y) to 4
7 (Ag), 57 (La) -79 (Au) and 89
It is a metal element consisting of four groups (Ac) to 111 in theory. The outer shell is d due to the imperfect d shell
The electrons have directionality, and as a result, excited electrons coming from the photocatalytic substance are easily captured on the surface of the metal ultrafine particles, and a superoxide anion is easily generated. From the viewpoint of long life, a noble metal is appropriate, and a metal which can be used as a catalyst by itself is desirable. For example, Au, Pt, Ag, p
d and Rh are preferable, and from the viewpoint of stability as a metal, A
u, Pt, and Pd are more preferred.

The quantum size effect exhibited by the ultrafine metal particles will be discussed below. For example, when ultrafine particles having a diameter of 1 nm are considered, only about 10 to 100 metal atoms are present therein, depending on the size of the atoms. Also diameter 1
About 0,000 to 1000, when it becomes 0 nm metal ultrafine particles
It is believed to contain 00 atoms. In such ultrafine metal particles having a small number of atoms, the electron energy state of the metal is gradually discretized from the band structure, and the energy levels are distributed over a wide range. This level discretization has the effect of increasing the relaxation time of the electrons, that is, the time required for the electron to fall from that level to the Fermi level. In other words, the time that electrons stay at the level becomes longer. At the same time, the wave function corresponding to the energy level protrudes to the outside of the metal while extending the tail to the left and right, and has the effect of reducing the peak at the same time. That is, the electrons on the wave function can easily move to the outside due to the quantum tunnel effect. In the present invention, the term “quantum size effect” means the occurrence of the quantum tunnel effect due to the discretization of the energy level and the delocalization of the wave function as described above. Therefore, as the particle size of the ultrafine metal particles becomes smaller, the quantum tunnel effect becomes larger. Therefore, it is desired to carry the ultrafine metal particles as small as possible.

Let us consider how a photocatalyst material carrying ultrafine metal particles can efficiently redox organic substances. When the photocatalytic substance is irradiated with excitation light such as ultraviolet light, electrons
Hole pairs are formed, and electrons are excited in the conduction band leaving holes in the valence band. The electron transitions to a higher position in the conduction band, but gradually loses energy and falls to the bottom of the conduction band. Since the energy levels of the metal are discretely dense to some extent, there is always an energy level corresponding to the bottom of the conduction band of the photocatalytic substance. Moreover, the wave function of the level has a long tail in the left and right, and extends from the inside of the titanium dioxide to the outside of the metal. That is, the energy levels of the photocatalytic substance and the metal are resonantly continuous via the wave function of the metal. Therefore, the excited electrons at the bottom of the conduction band are emitted at once by the quantum tunnel effect via the metal on the wave function of the metal. Since the photocatalytic substance and the metal are in a resonance state, this quantum tunnel effect is called resonance tunneling. The relaxation time is long because the levels in the metal are discretized, and electrons are easily emitted out of the metal before falling on the Fermi level of the metal.

The holes in the valence band of the photocatalytic substance move to the surface, oxidize the water attached to the surface to form a strong oxide called hydroxyl radical, and the hydroxyl radical oxidizes and decomposes the external substance. Is believed to be On the other hand, electrons emitted by resonance tunneling outside the metal reduce oxygen in the air to generate a superoxide anion called O ₂ ^—
It is thought that this anion is involved in the decomposition of external substances. In particular, in the present invention, since the excited electrons transferred to the metal are immediately discharged to the outside without being accumulated in the metal, an anti-power generation field is not formed outside, and the excited electrons can be successively attracted. Have power.

From a common sense point of view, the photocatalytic substance includes O ₂ potential as a reduction potential and OH as an oxidation potential.
A substance whose potential is located within the energy gap is selected. In other words, it is desirable to select a photocatalytic substance in which the reduction potential is located above the gap and the oxidation potential is located below the gap. In this case, the excited electrons fall to the reduction potential from the bottom of the conduction band to reduce the target substance, and the holes rise to the oxidation potential from the top of the valence band to oxidize the target substance. However, in the present invention, since the resonance tunneling of the ultrafine metal particles is effective, the reduction potential may be at the bottom of the conduction band or above it. That is, the electrons excited in the conduction band can immediately move horizontally to the O ₂ potential on the wave function of the metal before falling to the bottom. In this sense, the present invention has greatly expanded the selection range of photocatalytic substances.

[0020] For example, rutile titanium dioxide, since the O ₂ potential is located on 0.08eV from the bottom of the conduction band can not be conventionally used at all as a photocatalytic substance, other than the use of expensive anatase type titanium dioxide Did not. However, in the present invention, inexpensive rutile-type titanium dioxide can be used as a photocatalyst by resonance tunneling,
Its significance is groundbreaking.

A metal oxide semiconductor is suitable as a photocatalyst material satisfying the above properties. Since metal oxides are extremely stable substances as compared with simple metals, they have low reactivity with other substances, are safe, and can sufficiently exchange electrons. For example, WO ₃ , CdO ₃ , In ₂
O ₃ , Ag ₂ O, MnO ₂ , Cu ₂ O ₃ , Fe ₂ O ₃ ,
V ₂ O ₅ , TiO ₂ , ZrO ₂ , RuO ₂ , Cr
_{2 O 3, C O O 3} , NiO, SnO 2, CeO 2, Nb
₂ O ₃ , KTaO ₃ , SrTiO ₃ , K ₄ NbO _{17 and the} like. In particular, from the viewpoints of the electron-hole density, superoxide anion / hydroxyl radical density, corrosion resistance and safety as a material, Ti
O ₂ , SrTiO ₃ , and K ₄ NbO ₁₇ are preferred, and TiO _2, which is titanium dioxide, is most preferred. TiO ₂
As described above, not only the anatase type but also the rutile type can be used.

The photocatalytic substance which can be used in the present invention is a fine particle. Since the fine particles have an extremely large surface area, the probability of contact with environmental pollutants increases, and at the same time, a large number of metal ultrafine particles can be carried on the surface. Further, the fine particles have a larger effective light receiving area for ultraviolet rays and the like, and the photocatalytic efficiency is much higher than that of the bulk material. Since the metal oxide is usually a powder, a metal oxide semiconductor such as titanium dioxide is suitable for the present invention. The particle size is 30 nm to 10
00 nm, more preferably 50 nm to 500 nm. If the particle size is smaller than this, the particles approach the ultrafine particles, so that a special technique and cost are required for the production. If the particle size is larger than this, the specific surface area is reduced, and the reactivity with environmental pollutants, human toxic substances, malodorous substances and the like is deteriorated.

For example, it is possible to make titanium dioxide into ultra-fine particles of about 10 nm, but it does not exist as independent particles, but ultra-fine particles of titanium dioxide are aggregated and solidified in a cluster, and eventually the large titanium dioxide as described above It becomes a lump.
In this case, the reactivity is higher because the surface area is larger than that of a single solid due to the ruggedness. The present invention also includes the photocatalyst fine particles thus formed in a dumpling. The form of the photocatalyst fine particles is not particularly limited as long as the ultrafine metal particles can be supported.

The present invention is characterized in that the above-mentioned metal-supported photocatalyst fine particles are fixed in a dispersed manner on the surface of an adsorbent. Innumerable micropores (micropores) are formed on the surface of the adsorbent, and the diameter of the micropores is several nanometers.
In the present invention, the contaminant particles are adsorbed in the micropores, and then the contaminant particles adsorbed by the metal-supported photocatalyst fine particles are decomposed.

The adsorbent includes activated carbon, zeolite, porous ceramics, alumina, simple substance or composite of silica gel, etc., and collectively refers to substances capable of adsorbing contaminant particles on the surface. Examples of the form in which the adsorbent is actually used include a case where the adsorbent is used in the form of a powder, a case where the adsorbent is used in the form of a granule, and a case where the adsorbent is used in the form of a fibrous, planar, or solid body. I just need. In the case of a solid body, it is desired to have a honeycomb shape in order to increase the contact area with the contaminated air as much as possible. In the present invention, the solid body is referred to as an adsorptive honeycomb solid body. A large number of honeycomb holes may be formed to circulate the contaminated air. In the case of a flat solid body, the surface area can be increased by forming an infinite number of irregularities on the surface.

In the present invention, the fibrous adsorbent is referred to as an adsorbent fibrous body, and specific examples thereof include activated carbon fibers. In the case of a fibrous form, the total surface area can be extremely increased since the surface area of each fiber is added, and the weight of the metal-supported photocatalyst fine particles to be fixed can also be increased. The weight of the photocatalyst supporting ultrafine metal particles is 0.1 to 30%, preferably 1 to 20% of the fiber weight. In the form of fibers, fabrics such as woven, knitted and non-woven fabrics,
Examples thereof include fine cloth and fiber pieces such as short fibers, and other various forms.

There are various methods for immobilizing the metal-supported photocatalyst fine particles on the adsorbent. For example, an immersion method in which a powder composed of a photocatalyst carrying ultrafine metal particles is dispersed in an appropriate solvent, and an adsorbent is immersed in the solvent to fix the photocatalyst fine particles carrying metal. Further, there are also a spray method of spraying a solvent in which a photocatalyst supporting metal ultrafine particles is dispersed on a material, and a coating method using a roller or a brush. In addition, there is a method of electrostatically adsorbing a photocatalyst carrying ultrafine metal particles onto an adsorbent. Both the ultrafine metal-carrying photocatalyst particles and the adsorbent are naturally charged with static electricity,
A method of spray-fixing the powder of the ultrafine metal particle-supported photocatalyst fine particles to the adsorbent by this electrostatic attraction force, a method of pressing a material into the powder and fixing the same are used. In addition, the photocatalyst particles carrying ultrafine metal particles can be forcibly charged by corona discharge according to the principle of electric dust collection, and fixed to the surface of the adsorbent between the plates or on the plates by the electric field force between the plates. . By these methods, the material on which the ultrafine metal particle-supported photocatalyst fine particles are fixed can be heated to an appropriate temperature to be more firmly fixed to the material.

In order to fix the ultrafine metal particle-supported photocatalyst on the surface of the adsorptive fibrous body, the ultrafine metal particle-supported photocatalyst particles are fixed on the surface of the adsorptive fibrous body by the above-mentioned method, and then these fibers are heated at a predetermined temperature. By firing, the photocatalyst supporting ultrafine metal particles can be firmly fixed. Alternatively, after the raw fiber is carbonized by carbonization and activated carbon fiber by activation, the photocatalyst carrying ultrafine metal particles can be fixed on the activated carbon fiber by the method described above.

The raw materials of carbon fibers include rayon fibers, pitch fibers obtained by melt-spinning petroleum pitch and coal pitch, acrylic fibers, and many other fibers. These fibers are almost always transformed into carbon fibers or activated carbon fibers. The same firing method can be applied. Above all, the main raw material of carbon fiber is PAN (polyacrylonitrile), which is spun into acrylic fiber. The acrylic fiber will be described below.
The acrylic fiber is placed in an inert atmosphere at 1000 to 180
When heated at a temperature of 0 ° C., the acrylic fibers become carbon fibers. When this carbon fiber is activated in a mixed gas of water vapor, carbon dioxide and nitrogen, countless micropores
Thus, the activated carbon fiber having the particles formed thereon can be formed, and the activated carbon fiber holds the photocatalyst supporting the ultrafine metal particles. The self-cleaning decomposition ability can be remarkably improved by the adsorption power of the activated carbon fiber and the decomposition power of the photocatalyst supporting ultrafine metal particles.

The excitation light source that can be used in the present invention may be any light source having energy equal to or greater than the gap energy of the photocatalytic substance, and usually an ultraviolet lamp is used.
In particular, when titanium dioxide is used, there are a rutile type and an anatase type. When each gap energy is converted into a wavelength, the rutile type is 407 nm, and the anatase type is 38 nm.
8 nm. Accordingly, if the wavelength distribution of the light source for titanium dioxide has 400 nm near the peak, both can be accommodated. Among the ultraviolet lamps, the moth lamp is effective for both the rutile type and the anatase type since the peak at 400 nm is near the peak.

Natural sunlight is mainly visible light,
It can be fully utilized because it includes an energy region of 400 nm. Especially in the case of natural sunlight, it is 40 from 388 nm.
Since the light intensity is higher at 7 nm, the rutile type is more effective than the anatase type. In this case, the excitation light source is sunlight itself, and in a place where sunlight is not irradiated, a device for introducing sunlight from outside with an optical fiber or the like, a device for irradiating an adsorbent, or the like is an excitation light source. The fact that rutile titanium dioxide can be used as a photocatalyst according to the present invention opens a great way to utilize natural sunlight.
With conventional photocatalysts, the use of sunlight outdoors was possible due to the high light intensity, but indoor use was a weak point due to the low light intensity. However, in the present invention, since the photocatalytic efficiency has been remarkably enhanced, it has become possible to expand the use of the photocatalyst indoors using sunlight as a light source.

The simplest configuration of the air purifier according to the present invention is a combination of an adsorbent in which a metal-supported photocatalyst is dispersed and fixed, and an excitation light source. For example, there is a case where a metal-carrying photocatalyst is dispersed and fixed on a planar adsorbent (adsorption plate) and arranged on a wall, floor, ceiling, or the like, and natural sunlight or an ultraviolet lamp is used as an excitation light source. In this case, when the contaminated air comes into contact with the surface of the adsorbing plate due to natural convection of the indoor air, the adsorbing plate adsorbs the contaminant particles in the air, and the metal-supported photocatalyst is excited by the excitation light applied to the surface of the adsorbing plate. It acts to decompose pollutants. When natural sunlight is used as the excitation light source, it is necessary to dispose the adsorbing plate at an appropriate place where natural sunlight often enters. When an ultraviolet lamp is used as the excitation light source, it is desired to devise a method so that reflected light of ultraviolet rays does not hit the human body.
An air purifier is proposed in which a fan is added to the above-described configuration, and forced circulation of room air is performed to adsorb and decompose pollutants. The adsorption and decomposition efficiency can be increased by forced circulation. Further, similarly to the conventional air conditioner, the adsorbent, the excitation light source, and the fan may be provided in the casing, and the suction port and the discharge port may be provided to form an integrated air cleaner. It is safe because the excitation light does not leak outside due to the casing. Furthermore, if the function of the air purifier according to the present invention is additionally provided inside the conventional air conditioner, the air can be purified while controlling the temperature of the room air.

[0033]

1 is a partially broken front view of a first embodiment of an air purifier according to the present invention. The air purifier 2 includes a central purifier 4 and left and right side purifiers 6,6. The central purifier 4 is a device for decomposing pollutants heavier than air, such as living odors, and therefore has a suction port 8 below and a discharge port 10 above. The contaminated air is sucked from the suction port 8 by the fan F, and the adsorbent cloth 1 which is a kind of adsorbable fibrous body is absorbed.
After adsorbing and decomposing the contaminant particles in step 4, the purified air is discharged from the discharge port 10. Fan F uses a sirocco fan. Central sensor SS for detecting pollutants
Is located below the device for early detection of pollutants heavier than air and consists of a weak sensor SA and a strong sensor SB. Further, a drive control circuit C represented by a dotted line
C is a circuit for electronically controlling a sensor, a fan, and the following excitation light source.

FIG. 2 is a cross-sectional view taken along the line II of FIG. In order to increase the contact area with the contaminated air, the absorbent cloth 14 has three support rods 1.
6, the pumping light sources LA and LB are arranged horizontally in a zigzag shape in the front-rear direction, and the zigzag arrangement is reinforced by horizontally arranging the excitation light sources LA and LB. The flow of the contaminated air sucked by the fan F is as shown by the solid arrow. Excitation light source L
The excitation light from A and LB is irradiated directly or on the inner surface of the front plate 3 to the adsorptive cloth 14. In order to increase the reflectance, the front plate 3 may be formed of a metal such as aluminum, or a reflection film may be formed on the inner surface. The paths of the direct path and the reflected path of the excitation light are indicated by dotted arrows.

Further, as shown in FIG.
Is a device for breaking down contaminants lighter than air, such as tobacco smoke, and thus has an inlet 8 above and an outlet 10 below. A propeller-shaped fan F is disposed inside the suction port 8, and the adsorptive cloth 14
Are arranged in a zigzag pattern on the left and right. Three excitation light sources LC, LD, and LE are provided facing the adsorptive cloth 14. The contaminated air flows in the solid arrow direction by the fan F, and is discharged from the discharge port 10 while being in contact with the adsorptive cloth 14 arranged in zigzag. The contaminant particles adsorbed on the adsorptive cloth 14 are decomposed by the excitation light from the excitation light sources LC, LD, and LE. The excitation light is indicated by the dotted arrow. The side sensor S for detecting contaminants is disposed above the apparatus for early detection of contaminants lighter than air, and includes a weak sensor SC, a medium sensor SD, and a strong sensor SE. These sensors, fans and excitation light sources are also controlled by the drive control circuit CC.

FIG. 3 is an enlarged view of a main part of the adsorptive cloth 14,
It is a woven fabric obtained by weaving activated carbon fibers. The adsorptive cloth of the present embodiment may be anything other than such a woven cloth, such as a knit or a felt, as long as it forms a cloth.

FIG. 4 is a sectional view of a main part of the adsorptive fiber to which the metal-supported photocatalyst fine particles are fixed. The adsorptive fiber 18 is a fiber that constitutes an adsorptive fibrous body such as the adsorptive cloth 14, and the surface thereof has an infinite number of micropores (micropores) 2 having a pore diameter of several nm.
0 exists. As described above, the contaminant particles 22 are stuck and adsorbed in these micropores 20. On the other hand, a large number of metal ultrafine particles 26
Are fixed. In the present invention, the photocatalyst fine particles 24 supporting the metal ultrafine particles 26 are referred to as metal-supported photocatalyst fine particles 28. Titanium dioxide fine particles are often used for the photocatalytic fine particles 24, and noble metals such as Au and pt are often used for the ultrafine metal particles 26.

The particle diameter of the ultrafine metal particles 26 capable of exhibiting the quantum size effect is 10 nm or less. This particle size condition can be satisfied by preparing photocatalyst particles carrying ultrafine metal particles by a colloid firing method. Further, the carrying density needs to be 100 or more metal ultrafine particles per photocatalyst fine particle. This loading density condition can also be realized by a colloid firing method.

FIG. 5 shows innumerable metal-supported photocatalyst fine particles 28.
Are shown. This fixing state is not limited to the adsorptive fibrous body, but is similar in that a solid adsorbent is fixed on the surface in a dispersed manner.

Next, the operation of the drive control circuit CC for controlling the sensor, the fan and the excitation light source will be described with reference to a time chart. First, the operation of the central purifier 4 will be described. The weak sensor SA is adjusted to detect low-concentration contaminants, and the strong sensor SB is adjusted to detect high-concentration contaminants. FIG. 6 shows a central cleaner 4 for low concentration polluted air.
When the weak sensor SA detects the contamination concentration R of the contaminated air in the operation time chart of FIG.
A lights up. When the contamination concentration R falls below a certain value, the weak sensor SA turns off and the fan F stops. However, in order to decompose the contaminants, the excitation light source LA continues to light for a predetermined time thereafter, and at the same time, the excitation light source LB also lights for the same time.

The reason for the adjustment as described above is that the vicinity of the adsorbent cloth 14 near the fan is a starting point of the adsorption of the contaminated air and is easily contaminated. Decomposition is started by lighting. At the stage where the concentration of contamination becomes lower than a certain value due to the adsorption, the excitation light source LB is turned on in order to start disassembling the entire surface of the adsorptive cloth 14. As the lighting time T, a time required for completing the decomposition of the pollutant is set.

FIG. 7 is an operation time chart of the central purifier 4 for the high concentration polluted air. When the strong sensor SB detects the pollutant concentration R of the polluted air, the fan F is activated and both the excitation light sources LA and LB are turned on. . Since the contamination concentration is high, the entire surface of the adsorptive cloth 14 starts to be decomposed simultaneously with the start of the adsorption. When the concentration R decreases due to the adsorption due to the air circulation and the strong sensor SB is turned off, the excitation light source LB is turned off. However, at this stage, the weak sensor SA that reacts to the low contamination concentration is turned on. After the weak sensor SA is turned on, the operation is exactly the same as in FIG. However, a large amount of contaminants are adsorbed due to the high concentration of contaminants.
The lighting time T for disassembling A and LB is set longer than in the case of FIG.

Next, the operation of the side cleaner 6 will be described. The difference from the central purifier 4 is that a middle sensor SD for detecting a medium concentration of contaminants is provided, and the weak sensor SC and the strong sensor E correspond to low concentration contamination and high concentration contamination, respectively. FIG. 8 is an operation time chart of the side cleaner 6 with respect to the low concentration polluted air. When the weak sensor SC detects the pollution concentration R of the air polluted by cigarette smoke or the like, the fan F is activated and the excitation light source LC is turned on. I do. When the suction proceeds due to the rotation of the fan F and the contamination concentration R falls below a certain value, the weak sensor SC is turned off, the fan F is stopped, and the suction operation ends. At the same time, the excitation light sources LD and LE
Lights in the same manner as above to decompose the adsorbed contaminants. The time required for disassembly is set as the lighting time T. Inlet 8
Is located above, the vicinity of the suction port of the adsorptive cloth 14 is easily contaminated, and therefore, the excitation light source LC is adjusted to be turned on even during the suction operation.

FIG. 9 is an operation time chart of the side purifier 6 for the medium concentration polluted air. When the medium sensor SD detects the contamination concentration R of the polluted air, the fan F is operated and both the excitation light sources LC and LD are turned on. I do. When the contamination sensor R is turned off and the middle sensor SD is turned off, the excitation light source LD is turned off,
At about the same time, the weak sensor SC is turned on. Weak sensor S
After C is turned on, the operation is exactly the same as in FIG.
The description is omitted. However, the lighting time T of the excitation light source is set longer than in the case of FIG.

FIG. 10 is an operation time chart of the side cleaner 6 with respect to the high concentration polluted air. When the strong sensor SE detects the pollutant concentration R of the polluted air, the fan F is activated and all of the excitation light sources LC, LD and LE are activated. Lights up. When the contamination sensor R turns off and the strong sensor SE turns off, the excitation light source L
E goes out and the middle sensor SD turns on almost simultaneously. After the middle sensor SD is turned on, the operation is exactly the same as that of FIG. However, the lighting time T is set longer than in FIG.

As described above, the central purifier 4 is switched between strong and weak two-stages, whereas the side purifiers 6 and 6 are switched between strong, medium and weak three-stages. It is only designed for the number of excitation light sources. Actually, various designs are possible, and the detection of the contamination concentration, the adjustment of the lighting time, the number of lightings and the lighting intensity can be freely changed by the drive control circuit CC.

FIG. 11 is a partially cutaway front view of an air purifier according to a second embodiment of the present invention. Only parts different from those in FIG. 1 will be described, and other parts will be denoted by the same reference numerals. Description is omitted. The first embodiment uses the adsorbent cloth 14 as the adsorbent fiber body.
However, in the second embodiment, the absorbent gauze-like cloth 15 is used. This adsorptive gauze-like cloth 1
Reference numeral 5 denotes a fibrous body whose eyes are coarser than that of the adsorptive cloth 14, which is formed in a gauze or kayak shape to a degree capable of transmitting contaminated air and excitation light. Therefore, as indicated by solid arrows in the side cleaners 6, 6, the contaminated air is discharged from the outlet 10 while passing through the absorbent gauze-like cloth 15. That is, the contaminant particles are adsorbed on both surfaces of the adsorbent gauze, so that the adsorption efficiency can be remarkably improved. Also, as indicated by the dotted arrow, the excitation light also transmits through the adsorptive gauze-like cloth, so that both the direct light and the reflected light after transmission can be used as the excitation light, and the decomposition efficiency is significantly improved.

FIG. 12 is a sectional view taken along the line II of FIG. 11, and shows the flow of the contaminated air in the central cleaner 4 and the path of the excitation light. Just as in FIG. 11, the contaminated air and the excitation light can pass through the adsorptive gauze-like cloth 15, so that the adsorption and the decomposition can be performed on both surfaces, and the adsorption efficiency and the decomposition efficiency can be simultaneously improved.

FIG. 13 shows a third embodiment of the air purifier 2 according to the present invention.
This is an example. The contaminated air sucked from the suction port 8 by the fan F flows to both sides of the adsorptive cloth 14. The zigzag arrangement of the adsorptive cloth 14 is so fine that neither contaminated air nor excitation light can pass through the adsorptive cloth 14. In this method, both sides of the adsorptive cloth 14 are utilized by diverting contaminated air. Therefore, while the contaminated air is flowing by the driving of the fan F, the absorbent cloth 14
The contaminant particles are adsorbed on both surfaces of the substrate, and after the adsorption is completed, both surfaces are excited by the excitation light sources L, L,.

FIG. 14 shows a fourth embodiment of the air purifier 2 according to the present invention.
It is a perspective view showing an example. The contaminated air is sucked from the suction port 8 by the fan F composed of a sirocco fan and discharged from the discharge port 10. The adsorptive cloths 14 are arranged in a plurality of layers with a gap in the flow direction of the contaminated air, and a plurality of excitation light sources are arranged in the gap. Accordingly, when the contaminated air flows through the gap, the contaminant particles are adsorbed on both surfaces of the adsorptive cloth 14, and after being adsorbed, decomposed by the excitation light sources L, L,. In this embodiment, the contact area with the contaminated air is increased by stacking a plurality of adsorbent cloths, and the both sides thereof are utilized to increase the adsorption / decomposition efficiency.

FIG. 15 shows a fifth embodiment of the air purifier 2 according to the present invention.
It is a perspective view showing an example. The contaminated air is sucked from the suction port 8 by the rotation of the fan F and discharged from the discharge port 10. The adsorptive cloth 14 is spirally wound with a gap, the excitation light sources L, L... Are arranged in the gap, and contaminated air flows in the axial direction of the spiral cloth. Therefore, when the contaminated air flows through the gap, the absorbent cloth 14
The contaminant particles are adsorbed on both sides of the substrate, and after being adsorbed, decomposed by the excitation light sources L, L,. In this embodiment, the contact area with the contaminated air is increased by spirally winding the adsorptive cloth, and the adsorption / decomposition efficiency is increased by utilizing both surfaces.

FIG. 16 shows a sixth embodiment of the air purifier 2 according to the present invention.
It is a perspective view showing an example. The contaminated air is sucked from the suction port 8 by the rotation of the fan F and discharged from the discharge port 10. The adsorptive fibrous body is constituted by an adsorptive gauze-like cloth 15 that easily transmits contaminated air, and the adsorptive gauze-like cloths 15 are arranged in a plurality of layers with an interval therebetween.
The contaminant particles are adsorbed while allowing the contaminated air to pass through 5, 15,. When the adsorption is completed, the excitation light sources L and L
Turn on to break down the contaminant particles. In this example,
The contact area with the contaminated air is increased by arranging the adsorbent gauze-like cloth 15 in a plurality of layers perpendicular to the flow direction of the contaminated air, and the both sides thereof are used to increase the adsorption / decomposition efficiency. .

FIG. 17 shows a seventh embodiment of the air purifier 2 according to the present invention.
It is a perspective view showing an example. The contaminated air is sucked from the suction port 8 by the rotation of the fan F and discharged from the discharge port 10. A suction housing BX is disposed between the suction housings, and upper and lower surfaces thereof are air ports made of a mesh or the like. The suction housing BX is filled with the adsorptive fiber pieces 13. In this embodiment, the adsorptive fiber piece 13 is an aggregate of a large number of adsorptive short fibers. However, a single long fiber may be wound or an aggregate of a plurality of long fibers. Also, an aggregate of small adsorptive cloths may be used. At least the three-dimensional sparse structure should be sufficient to convey the contaminated air.
That is, the contaminated air flows while being pressure-fed between the adsorptive fiber pieces 13 by the fan F, and the contaminant particles are adsorbed. Thereafter, decomposition is performed by turning on the excitation light source L. In this embodiment, since the adsorbable fiber pieces having the three-dimensionally sparse structure are brought into contact with the contaminated air, the contact area is larger than that of the planar structure, and the adsorption / decomposition efficiency can be increased.

FIG. 18 shows an eighth embodiment of the air purifier 2 according to the present invention.
It is sectional drawing which shows an Example. In particular, the air purifier 2 is designed to be an air-conditioning type capable of heating and cooling. The contaminated air is sucked from the suction port 8 by the rotation of the fan F and discharged from the discharge port 10. After passing through the heat exchanger 30, the contaminated air sucked from the suction port 8 is sent to the adsorbent solid body 17 as an adsorbent. Although an adsorptive fibrous body has been used in the above embodiments, an adsorptive solid body is used in this embodiment. A large number of honeycomb holes 19 are formed in the flow direction in order to allow the contaminated air to pass therethrough. Metal-supported photocatalyst fine particles are dispersed and fixed on the inner surface of the honeycomb holes 19. An excitation light source L is arranged in the vicinity,
After adsorbing the contaminant particles, the decomposition is performed by the excitation light. When a solid adsorbent is used, not only a honeycomb solid body but also an adsorbent solid body having a large number of communication holes in order to increase a surface area may be formed, and contaminated air may be pumped.

The present invention is not limited to the above-described embodiment, but encompasses various modifications and design changes within the technical scope without departing from the technical idea of the present invention.

[0056]

As described in detail above, the present invention has a particle size of 1%.
Since a metal-supported photocatalyst carrying ultrafine metal particles of 0 nm or less is used, the photocatalytic efficiency can be significantly increased due to the development of the quantum size effect, and an improvement in the air purification function can be achieved. In addition, if metal-supported photocatalyst fine particles in which 100 or more of these metal ultrafine particles are supported per photocatalyst fine particle are used, an air purifier using a photocatalyst can be obtained by a quantum size effect and a high density support effect of the metal ultrafine particles. It has the effect of dramatically increasing the purification function. In addition, since a large number of the metal-supported photocatalyst fine particles are dispersed and fixed on the surface of the adsorbent, the contaminant particles are first adsorbed on the adsorbent, and then can be decomposed with high efficiency, and the environment can be maintained in a highly sanitary state. Having. At the same time, since the highly efficient metal-supported photocatalyst almost completely decomposes the contaminant particles adsorbed on the adsorbent, there is an effect that the adsorbent can be used for a long time. Furthermore, when an adsorbent fibrous body is used as the adsorbent, the surface area of the fiber is extremely large as compared with the solid body, so that the adsorbing effect and the decomposing effect can be increased, and the air purifier can be made even more efficient. Has effects that can be achieved.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a first embodiment of an air purifier according to the present invention.

FIG. 2 is a sectional view taken along line II of FIG. 1;

FIG. 3 is an enlarged view of a main part of the adsorptive cloth.

FIG. 4 is a cross-sectional view of a main part of an adsorptive fiber to which metal-supported photocatalyst fine particles are fixed.

FIG. 5 is an external view of an adsorptive fiber on which countless metal-supported photocatalyst fine particles are fixed.

FIG. 6 is an operation time chart of the central purifier for low-concentration polluted air.

FIG. 7 is an operation time chart of the central purifier for highly contaminated air.

FIG. 8 is an operation time chart of the side purifier for low-concentration polluted air.

FIG. 9 is an operation time chart of the side purifier with respect to the medium concentration polluted air.

FIG. 10 is an operation time chart of the side cleaner 6 for highly contaminated air.

FIG. 11 is a partially cutaway front view of a second embodiment of the air purifier according to the present invention.

FIG. 12 is a sectional view taken along line II of FIG. 11;

FIG. 13 is a third embodiment of the air purifier according to the present invention.

FIG. 14 is a perspective view showing a fourth embodiment of the air purifier according to the present invention.

FIG. 15 is a perspective view showing a fifth embodiment of the air purifier according to the present invention.

FIG. 16 is a perspective view showing a sixth embodiment of the air purifier according to the present invention.

FIG. 17 is a perspective view showing a seventh embodiment of the air purifier according to the present invention.

FIG. 18 is a sectional view showing an eighth embodiment of the air purifier according to the present invention.

[Explanation of symbols]

 2 ··· Air cleaner 3 · · · front plate 4 · · · central cleaner 6 · · · side cleaner 8 · · · suction port 10 · · · discharge port 13 · · adsorbent fiber pieces 14 · · · adsorbent cloth 15 · · · Adsorbent gauze-like cloth 16 ・ ・ Support rod 17 ・ ・ Adsorbent honeycomb solid body 18 ・ ・ Adsorbent fiber 19 ・ ・ Honeycomb holes 20 ・ ・ Micropores (micro holes) 22 ・ ・ Pollutant particles 24 -Ultrafine metal particles 28-Metallic photocatalyst particles 30-Heat exchanger BX-Adsorption housing CC-Drive control circuit F-Fan L, LA, LB, LC, LD, LE-Excitation light source R・ ・ Pollution concentration S ・ ・ Side sensor SA 、 SC ・ ・ Weak sensor SD ・ ・ Medium sensor SB 、 SE ・ ・ Strong sensor SS ・ ・ Center sensor T ・ ・ Lighting time

Claims (14)

[Claims] Claims: 1. Use of metal-supported photocatalyst fine particles in which ultrafine metal particles having a particle size of 10 nm or less are supported on photocatalyst fine particles,
An adsorbent in which a large number of the metal-supported photocatalyst fine particles are dispersed and fixed is arranged, and an excitation light source for irradiating the adsorbent with excitation light is provided. A metal-supported photocatalyst-type air purifier characterized by decomposing adsorbed contaminants with metal-supported photocatalyst fine particles by irradiating the air. 2. The air purifier according to claim 1, wherein metal-supported photocatalyst fine particles having at least 100 ultrafine metal particles having a particle size of 10 nm or less per photocatalyst fine particle are used. 3. The air purifier according to claim 1, further comprising a fan for forcibly blowing contaminated air to the adsorbent. 4. The air purifier according to claim 3, further comprising a suction port for taking in the contaminated air, and a discharge port for discharging the air after adsorbing the contaminant particles on the adsorbent. 5. A sensor for detecting a contaminant in contaminated air, and a drive control circuit for driving and controlling a fan and an excitation light source based on a signal from the sensor.
An air purifier as described. 6. The sensor and the excitation light source are each provided in a plurality of stages, and the contaminant detection concentration of each sensor is set in a stepwise manner.
The air purifier according to claim 5, wherein the lighting time or the number of lighting of the excitation light source is controlled according to the level of the contamination concentration. 7. The air purifier according to claim 1, wherein the adsorbent is made of an adsorbent fibrous body. 8. The adsorptive fiber body is constituted by an adsorptive cloth,
The air purifier according to claim 7, wherein the adsorptive cloth is arranged in a zigzag to increase the contact area with the contaminated air. 9. The adsorbent cloth is made of an adsorbent gauze-like cloth through which contaminated air is easily transmitted, and the contaminant particles are adsorbed while the contaminated air is transmitted through the adsorbent gauze-like cloth.
An air purifier as described. 10. The adsorptive fiber body is constituted by an adsorptive cloth, the adsorptive cloth is arranged in a plurality of layers so as to have a gap in the flow direction of contaminated air, and an excitation light source is arranged in the gap. The air purifier according to claim 7, wherein contaminated air is passed through the gap. 11. The adsorptive fibrous body is constituted by an adsorptive cloth, and the adsorptive cloth is spirally wound so as to have a gap, and an excitation light source is arranged in the gap. The air purifier according to claim 7, wherein contaminated air is passed. 12. The adsorptive gauze-like cloth is composed of an adsorptive gauze-like cloth through which contaminated air is easily transmitted, and the adsorptive gauze-like cloth is arranged in a plurality of stages with intervals. The air purifier according to claim 7, wherein the contaminant particles are adsorbed while allowing the contaminated air to pass therethrough. 13. The adsorptive fiber body is constituted by an adsorptive fiber piece, the adsorptive fiber piece is filled in an adsorption housing, and contaminated air is pumped through the adsorption housing. The air purifier according to claim 7, wherein the contaminant particles are adsorbed on the adsorptive fiber pieces. 14. The adsorbent is a solid adsorbent honeycomb body having a honeycomb hole through which contaminated air passes.
7. An air purifier according to claim 6.