JP2991195B1 - Air purifier and air cleaning system using environmental catalyst - Google Patents

Abstract

The present invention relates to a catalyst having an air purifying action (hereinafter referred to as an environmental catalyst), and more particularly to an environmental catalyst capable of purifying a large amount of contaminated air by combining fullerenes and a photocatalyst, and an environmental catalyst. It is an object to provide an air purifier used. SOLUTION: Since a photocatalyst and a noble metal are supported on the surface of a thin film of a carbon material containing fullerenes, the efficiency of adsorption and desorption of a large amount of gas can be increased. It is possible to easily release the adsorbate outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst having an air purifying action (hereinafter referred to as an environmental catalyst), and in particular, a large amount of contaminated air can be purified by combining a fullerene and a photocatalyst.
The present invention relates to an air purifier using an environmental catalyst .

[0002]

2. Description of the Related Art In recent years, a photocatalyst has been receiving attention as an effective substance for purifying air. This is because, by irradiating the photocatalyst with light of a certain wavelength, electrons in the valence band of the photocatalyst obtain light energy and move to the conduction band, and the resulting electrons and holes are organic compounds present around the photocatalyst. And the like, and the property of causing a chemical reaction such as an oxidation-reduction reaction is used. Therefore, most semiconductors have such a photocatalytic action, and among them, TiO ₂ is often used because of its excellent stability (heat resistance and chemical resistance).

[0003] Such photocatalysts themselves do not have sufficient adsorption capacity, and when used alone, it is difficult for the object to be treated to reach the photocatalyst, and there is a limit to the processing capacity. There is also a technology to support the photocatalyst on ceramics such as alumina.However, since the ceramic itself has a poor adsorption capacity, a concentration gradient of the processing target is set in order to reach the processing target on the photocatalyst, or forced by a blower. There is a means to reach the target, and the processing efficiency is generally poor.

[0004] In order to overcome these drawbacks, there is disclosed an invention in which a photocatalyst is used in combination with a carbon-based material represented by activated carbon. For example, JP-A-2-20782
No. 4 and Japanese Patent Application Laid-Open No. 4-34444 disclose an air cleaning apparatus provided with an activated carbon layer and a photocatalyst layer independently. An object of these inventions is to extend the life of activated carbon by sharing the treatment of low-boiling nitrides and low-boiling aldehydes that cannot be completely treated with activated carbon with a photocatalyst. Certainly, the gas can be treated more efficiently than the treatment with the photocatalyst alone or the activated carbon alone, but since each is used independently, the treatment amount is limited. When the adsorption capacity of activated carbon is deteriorated, a method is adopted in which activated carbon is replaced or the adsorbed substance is released by heating and treated with a photocatalyst. In the case of release by heating, heating at a relatively high temperature is required, which is not suitable for applications that require stable processing of a large amount of gas.

Japanese Patent Application Laid-Open No. 8-332378 discloses an invention relating to a deodorizing photocatalyst containing titanium oxide-supported activated carbon which has been carbonized and activated in the presence of Ti as a main component. Specifically, this catalyst is activated and prepared by uniformly mixing an activated carbon precursor organic compound and a Ti-containing solution, carbonizing by firing, and high-temperature treatment with steam or the like. The resulting catalyst is a composite catalyst in which a photocatalyst is supported on activated carbon, and the object to be treated is adsorbed on activated carbon in the vicinity of the photocatalyst, so that the efficiency of the object to be treated reaching the photocatalyst is good. However, activated carbon and carbon fiber have some problems from the viewpoint of treating a large amount of gas because the adsorption capacity is too high.

[0006] That is, activated carbon and carbon fiber are difficult to desorb the gas once adsorbed, so that the adsorption rate decreases rapidly as the gas is treated, and the adsorbed gas is released by heating to regenerate the catalyst. Also, there is a problem in practical use from the viewpoint of requiring a relatively high temperature and treating a large amount of pollutant gas.

As described above, although there are conventional technologies such as a combined use of a photocatalyst and a carbon-based material and a composite of a photocatalyst and activated carbon or carbon fiber, there is a problem with a technology for treating gas in a large amount, stably and efficiently. There was no disclosure.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a large amount of gas can be treated easily by adsorbing and desorbing an object to be treated by compounding a photocatalyst with fullerenes. An object of the present invention is to provide an air purifier using an environmental catalyst.

[0009]

According to the present invention, there is provided a reaction vessel having a composite catalyst , comprising: a carbon material containing fullerenes for adsorbing a gas containing an object to be treated; and a photocatalyst for decomposing the object to be treated. And the composite catalyst in the reactor
Light irradiating means for irradiating external light or visible light;
And a heating and cooling means for heating and cooling the medium .

Further, the present invention provides a reaction vessel having a composite catalyst comprising a carbon material containing fullerenes for adsorbing a gas containing an object to be treated and a photocatalyst for decomposing the object to be treated.
Irradiating the composite catalyst with ultraviolet or visible light in the reactor
A light irradiation unit, and a heating / cooling unit for heating / cooling the composite catalyst
An air purifier having a step , wherein the carbon material containing fullerenes is formed in a layer on the carrier, and the carbon material containing fullerenes formed in the layer is
Characterized by having a structure in which photocatalyst particles are arranged
Air purifier .

Further, the present invention provides a reaction comprising a composite material comprising a carbon material containing fullerenes for adsorbing a gas containing an object to be treated, a photocatalyst for decomposing the object to be treated, and a noble metal.
UV or visible light to the composite catalyst in the vessel and the reactor
Irradiating light, and heating and cooling the composite catalyst
An air purifier and a heating and cooling means, the fullerenes are formed in layers on the support, on top of the carbon material containing fullerenes formed in this layer, the
Photocatalyst particles are arranged, and the layered
Of both the carbon material containing larens and the photocatalyst particles
Have a structure in which noble metal particles are arranged on the surface.
And an air purifier characterized by the following .

[0012]

Further, the present invention is an air cleaning system having at least two or more of the above air purifiers, wherein an inlet for introducing a gas containing an object to be treated, and two or more of the introduced gas are used.
Gas flow path switching means for distributing to the above air purifier,
Control means for cooling a composite catalyst of at least one of the two or more air purifiers while the composite catalyst of the other air purifier is being heated.

The inventor of the present application has found that a fullerene can adsorb a large amount of gas as compared with activated carbon, and has a property of releasing an adsorbed gas at a relatively low temperature.

That is, by combining the fullerenes and the photocatalyst, not only the efficiency of the processing gas reaching the photocatalyst is high, but also the amount of gas existing near the photocatalyst increases, and the decomposition treatment can be performed efficiently. Becomes further,
By utilizing the property that fullerenes release adsorbed gas at a relatively low temperature, it is possible to release untreated gas or release already decomposed gas by heating. Easy to do.

By using this environmental catalyst, an air purifier for processing a large amount of gas can be produced. For example, an air purifier in which the composite catalyst of the present invention is disposed in a reaction vessel, has means for irradiating the composite catalyst with ultraviolet light or visible light, and is provided with a heating / cooling mechanism capable of heating and cooling the composite catalyst. Vessels. This device enables the decomposition treatment of a large amount of gas by adopting the structure of the composite catalyst, and also releases the non-treated gas and the decomposed gas by heating and cooling the composite catalyst, thereby decomposing the catalyst. Reactivation is possible. Further, there is an air cleaning system having two or more air purifiers and having a mechanism for alternately heating and cooling the composite catalyst. The advantage of this device is that a large amount of gas can be treated and the reactivation of the composite catalyst is alternately performed, so that long-term continuous operation can be performed efficiently without maintenance work.

[0017]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the air of the present invention.
1 shows a cross-sectional view of one embodiment of an environmental catalyst used in a purifier . In FIG. 1, a carbon material 12 containing fullerenes is formed in a layer on a substrate 11 as a carrier, and photocatalyst particles 13 are arranged on the carbon material containing fullerenes formed in a layer. Structure.

The fullerenes include C ₆₀ , C ₇₀ ,
C ₇₆ , C ₇₈ , C ₈₂ and C ₈₄ are exemplified. These groups of compounds have a property of easily adsorbing a large amount of molecules and a property of easily releasing the adsorbed molecules at a relatively low temperature. The reason for this is not clear, but the inventor believes that these compounds have unique molecular structures like soccer balls and rugby balls, and therefore have unique properties not found in diamond and graphite, which are also carbon allotropes. Is thinking.

In this figure, a flat substrate is used as a carrier, and a carbon material containing fullerenes is formed thereon in a layered form. Any shape may be used as long as it has a shape. For example, it may be a formed article formed into a honeycomb shape or a structure obtained by knitting a fibrous thing. Since the surface of the carrier is covered with a carbon material containing fullerenes, the material is not particularly limited as long as the material has heat resistance to the photocatalyst carrying process and the heating temperature during the operation of the air purifier. Is preferred. For example, alumina, zeolite, silica gel, silica alumina, and the like, which are used as a carrier for the catalyst, are preferably used.

As a method of forming fullerenes in a layered form, for example, there is a method by molecular beam evaporation. However, more simply, the fullerenes are dissolved in a non-polar solvent such as benzene, and then the carrier is added to this solution. The carrier is immersed and then dried by heating in an inert gas at a temperature of about 400 ° C., whereby fullerenes can be formed in a layer on the carrier. As the thickness of the fullerene layer, 0.5 μm to
About 10 μm is preferable.

The fullerenes need only be substantially the main component, and can be diluted with a carbon material such as activated carbon or carbon fiber in consideration of moldability, film formability and cost. For example, such a carbon material can be added to fullerenes within a range of 50% or less, more preferably within a range of 10%, to improve moldability.

Next, a photocatalyst is disposed on the carbon material containing fullerenes formed in the form of a layer to form a composite catalyst. Theoretically, semiconductors have a photocatalytic effect,
It can be used as a photocatalyst, but 2-3 eV
For example, CdS (band gap 2.5 eV), TiO ₂ (band gap 3.0 eV), and SrTiO ₃ (band gap 3.2 e) having a band gap of about
V), GaP (band gap 2.2 eV) or the like can be suitably used. The configuration of the photocatalyst is, for example, on a carbon material containing fullerenes formed in a layered form, it is also possible to form a stripe shape, a lattice shape, but dispersed in a particle shape that can easily obtain a surface area The arrangement configuration is preferable.

In order to obtain such a shape, a crystal is grown by sputter deposition on a layered carbon material containing fullerenes, or a substrate on which the carbon material containing fullerenes is formed is photocatalyzed. Alternatively, the photocatalyst can be formed into particles by immersion in a solution containing the precursor, precipitation on the surface of the substrate, further baking, or immersion in a solution containing the photocatalyst or the precursor, and irradiation with ultraviolet light. The average particle diameter of the photocatalyst is preferably 100 μm or less.

Further, as shown in FIG. 2, fine noble metal particles can be arranged on a carbon material containing fullerenes and a photocatalyst. A carbon material including fullerenes is formed in a layer on a substrate 21, a photocatalyst 23 is disposed thereon, and fine particles of a noble metal 24 are further disposed.

As the noble metal, for example, Pd, Pt, R
h, Ru, Ir, Au, and Ag. Further, a combination of two or more of these types is also conceivable.

By combining such a noble metal fine particle, electrons and holes generated when the photocatalyst is irradiated with light can be efficiently separated, and the performance as a photocatalyst can be improved.

In order to obtain such an arrangement, fine particles can be deposited by immersing the substrate shown in FIG. 1 in a solution containing a noble metal element and then performing a reduction treatment. The average particle size of the noble metal fine particles is preferably 500 nm or less. Further, alloying or compounding may be performed by using a solution containing two or more kinds of noble metals.

As described above, the photocatalyst and the noble metal material are disposed on the fullerene layer which enables the adsorption and desorption of a large amount of gas at a relatively low temperature, and the active oxygen generated when the photocatalyst is irradiated with ultraviolet rays. And radicals can effectively react with a large amount of the substance to be treated adsorbed by the fullerenes, and the substance to be treated can be decomposed with high efficiency.

FIG. 3 is a view showing an embodiment of an air cleaning system using an environmental catalyst of the present invention. This figure is 2
1 shows an air cleaning system having a series of air purifiers, heating and cooling means, and gas flow switching means.

First, an air purifier for processing a gas containing a processing object (hereinafter referred to as a pollutant gas) using an environmental catalyst will be described. This air purifier includes a reaction vessel 37 (same as 38 in this figure), an environmental catalyst 31 of the present invention (same as 32 in this figure), and ultraviolet irradiation means 33 (3 in this figure).
4) and a heating / cooling means 38 (commonly used in the two series of air purifiers in this figure).

The reaction vessel is a vessel for retaining and treating the contaminated air for a certain time. The ultraviolet irradiation means is, for example, a means for irradiating ultraviolet light such as an ultraviolet lamp, and the wavelength of the irradiation light can be selected to be a wavelength at which the photocatalyst exhibits the highest processing ability. For example,
When TiO ₂ is selected as the photocatalyst, a mercury lamp that emits ultraviolet light having a wavelength of 254 nm can be suitably used.

The heating / cooling means is a heating / cooling means for reactivating the composite catalyst. By heating the composite catalyst, the composite catalyst is mainly decomposed by a non-treatment gas or photocatalyst to which a carbon material containing fullerenes is adsorbed. By releasing the treated gas that has been treated and then rapidly cooling it, the catalyst can be efficiently reactivated. Further, a method of cooling the composite catalyst during the treatment operation and heating the composite catalyst at the time of reactivation may be adopted.

As for the heating ability, fullerenes can be heated to about 40 ° C. to 60 ° C. because they have good gas releasing properties at low temperatures, and heating with a commonly used heater is sufficient. In the case of a composite catalyst in which activated carbon or carbon fiber is combined with a photocatalyst, considering that it requires at least 100 ° C. or more, it can be reactivated at a considerably low temperature, which is extremely advantageous in terms of process. . Further, the cooling capacity is sufficient if the composite catalyst has an ability to cool the composite catalyst to 0 ° C. or less, and can be achieved by, for example, bringing a refrigerant cooled to about 0 ° C. or less into thermal contact.

Next, an operation method of the air cleaning system will be described. The contaminated air is introduced from the gas inlet in the figure, and is guided to either the flow path 1 or the flow path 2 by the gas introduction flow path switching means (the valve 39 in the figure). For example, contaminated air is introduced into the reaction vessel 37 through the flow path 1, and is decomposed by the environmental catalyst 31 and the light irradiation unit 33. At this time, the environmental catalyst 31 is cooled by the heating and cooling means 35. At the same time, gas exhaust switching means (valve 4 in the figure)
By 0), control is performed such that the decomposed gas in the reaction vessel 37 is exhausted. When the processing capacity of the environmental catalyst 31 has been degraded by the treatment for a certain period of time, the polluted gas is introduced into the reaction vessel 38 through the flow path 2 and
Perform the same operation as for. Therefore, valve 39,
40 are both open to the flow path 2 and closed to the flow path 1. At this time, the environmental catalyst 31 is heat-treated by the heating / cooling means 35 to reactivate it. Next, when the processing capacity of the environmental catalyst 32 deteriorates, it is reactivated by the same operation as in the case of the environmental catalyst 31. As described above, by systematically controlling the gas introduction flow path switching means, the gas exhaust flow path switching means, and the heating / cooling means by the control means 38, it is possible to operate without maintenance work for a long time.

Example 1 An alumina substrate was immersed in a solution obtained by dissolving commercially available purified _C60 fine particles in benzene.
About 40 in inert gas such as helium, argon and nitrogen
By heating to 0 ° C., the solvent was evaporated to form a _C60 fine particle thin film on the substrate. Immersed alumina substrate formed with the C ₆₀ film on the surface of the titanium sulfate 10g in the titanium sulphate solution prepared by dissolving in water 50 g, sufficiently slowly added while stirring concentration of 14% ammonia water until the pH7.0 . Thereafter, the temperature of the solution was raised to 60 ° C. and left for 24 hours.
The substrate was washed and fired at 110 ° C. for 2 hours in a nitrogen atmosphere. After that, by observing the substrate with a SEM device, it was found that the surface of the alumina substrate had a thickness of about 1
C ₆₀ films of 0μm is formed, it was confirmed that the on the titanium oxide photocatalyst particles (having an average particle diameter of about 5 [mu] m) is formed. In this embodiment, no carbon material other than fullerene is used. Placed in each reaction vessel of the reaction system with two gas flow paths as shown in FIG. 3 the catalyst having the above manner with the C ₆₀ formed on an alumina substrate and a titanium oxide, a position can be irradiated to the catalyst Was equipped with an ultraviolet lamp. The catalyst on the gas introduction side is cooled to 10 ° C. or less, and acetaldehyde 10 p
Air containing pm was introduced into one flow path and sealed. 20
After a minute, the residual gas in the reaction vessel is sampled and analyzed by GC-
As a result of analysis with an MS device, the substance to be treated, acetaldehyde, was below the detection limit. After that, the valve was switched, and the temperature of the catalyst in the reaction vessel in the other flow path was raised to 10 ° C.
After cooling, a gas containing the same substance to be treated was introduced and sealed, and the catalyst in the channel where the reaction was completed was heated to about 30 ° C. or more so that the adsorbed gas could be released. When the released gas was analyzed by a GC-MS device, the substance to be treated, acetaldehyde, was below the detection limit. The treatment test was performed for a long time by repeating the above reaction.
No deterioration in processing performance was observed even after the treatment for 000 hours.

[0036] (Example 2) an alumina substrate C ₆₀ particle film and the titanium oxide described is formed on the surface in Example 1 with palladium chloride 43g ammonium chloroplatinic acid 46g
Immersed in a solution of 500 g of water, heated to 80 ° C. and left for 24 hours, then heated to 40 ° C.
Left for hours. After washing the substrate thus obtained,
120 ° C. under a hydrogen atmosphere (SV / h−1 = 12000)
For 2 hours, and then at 400 ° C. for 1 hour. Observation of the surface of the substrate thus obtained with an SEM device confirmed that fine particles of Pd-Pt (average particle size: about 200 nm) were formed on the surface of the titanium oxide particles. The substrates obtained as described above were placed in two reaction vessels of the same reaction system as in Example 1. 20 ppm of trimethylamine as a substance to be treated was introduced into the cooled reaction vessel of the catalyst and sealed. Twenty minutes later, the sealed gas was sampled and analyzed by a GC-MS apparatus. As a result, the target substance, trimethylamine, was below the detection limit. When the same encapsulation and release processes as in Example 1 were repeated, trimethylamine in the released gas was below the detection limit, and no reduction in treatment performance was observed even after 3000 hours.

[0037]

As described above, the air purifier of the present invention is
The environmental catalyst used in the vessel consists of a carbon material containing fullerenes formed on a carrier in the form of a thin film, on which a photocatalyst or a photocatalyst and a noble metal material are formed. Since the arrival efficiency of the substance to be treated to the photocatalyst can be increased and the release of the adsorbed gas (particularly, the non-treatment gas) can be facilitated, a highly efficient treatment capacity can be maintained for a long period of time. Further, an air purifier using this catalyst can easily adsorb and release gas, and thus can maintain the processing capacity for a long time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a composite catalyst used in the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a composite catalyst used in the present invention.

FIG. 3 is a schematic view showing one embodiment of an air purifier system using the composite catalyst of the present invention.

Claims (7)

(57) [Claims] 1. A reaction vessel having a composite catalyst containing a carbon material containing fullerenes for adsorbing a gas containing an object to be treated and a photocatalyst for decomposing the object to be treated ,
Light irradiation means for irradiating the combined catalyst with ultraviolet light or visible light,
Heating and cooling means for heating and cooling the composite catalyst
Air purifier. 2. A reaction vessel having a composite catalyst comprising a carbon material containing fullerenes for adsorbing a gas containing a treatment object and a photocatalyst for decomposing the treatment object , wherein the reaction vessel has a composite catalyst.
Light irradiation means for irradiating the combined catalyst with ultraviolet light or visible light,
Heating and cooling means for heating and cooling the composite catalyst
A gas purifier , wherein the carbon material containing fullerenes is formed in a layer on a carrier, and the photocatalyst particles are arranged on the carbon material containing fullerenes formed in the layer. Air purifier characterized by having
vessel. 3. A reaction vessel having a carbon material containing fullerenes for adsorbing a gas containing a treatment object, a photocatalyst for decomposing the treatment object, and a composite catalyst comprising a noble metal ,
Irradiating the composite catalyst with ultraviolet or visible light in the reactor
Injection means, heating and cooling means for heating and cooling the composite catalyst
An air purifier with a carbon material containing the fullerenes are formed in layers on the support, on top of the carbon material containing fullerenes formed in this layer, the photocatalyst particles are placed and, on the surface of both the carbon materials and the photocatalyst particles containing fullerenes formed in the layered, this having a structure in which fine noble metal particles are arranged
An air purifier characterized by the following. 4. The method according to claim 1, wherein the fullerenes are C ₆₀ , C ₇₀ ,
_{C 76, C 78, C 82} , empty according to claim 1, wherein a fullerene represented by any of formulas of C ₈₄
Air purifier . 5. The photocatalyst is CdS, TiO ₂ , SrT.
iO _3, air cleaner according to claim 1 a photocatalyst represented by any one formula of GaP containing at least 1 or more. 6. The method according to claim 1, wherein the noble metal is Pd, Pt, Rh, R
at least one of u, Ir, Au and Ag
Air Kiyoshi Kiyoshiki of claim 3 wherein the metal containing more than. 7. An air purifying system comprising at least two air purifiers according to claim 1, wherein an inlet for introducing a gas containing an object to be treated is provided, A gas passage switching means for distributing to the air purifier described above, and a composite catalyst for another air purifier when heating the composite catalyst for at least one of the two or more air purifiers. Air cleaning system having a control means for cooling the air.