WO2004052536A1

WO2004052536A1 - Composite catalyst for removing carbon monoxide and method for removing carbon monoxide using the same

Info

Publication number: WO2004052536A1
Application number: PCT/JP2003/015135
Authority: WO
Inventors: Hiroaki Sakurai; Susumu Tsubota; Masatake Haruta
Original assignee: National Institute Of Advanced Industrial Science And Technology
Priority date: 2002-12-06
Filing date: 2003-11-27
Publication date: 2004-06-24
Also published as: JP2004188243A; JP4119974B2; AU2003302884A1

Abstract

A composite catalyst for removing carbon monoxide which comprises a gold nano-particulate catalyst comprising gold particles having an average particle diameter of 25 nm or less carried on a metal oxide and an alkaline porous material; and a method for removing carbon monoxide using the composite catalyst. The composite catalyst can be used for removing carbon monoxide over a wide range of the concentration of carbon monoxide from a low to a high concentration and is capable of maintaining high activity at an ordinary temperature for a long period of time, and thus can be advantageously used for removing carbon monoxide from a gas in a living space.

Description

Description: Catalyst composite for removing carbon monoxide and method for removing carbon monoxide using the same

The present invention relates to a catalyst composite for removing carbon monoxide and a method for removing carbon monoxide using the same. More specifically, the present invention relates to a catalyst composite for removing carbon monoxide in gases derived from incomplete combustion, smoking, automobile exhaust gas, and the like, which are problems in living environment X, and a method for removing carbon monoxide using the same. Background art

Carbon monoxide is a highly toxic gas, and its coexistence in the air of the living environment has a serious effect on the human body. Therefore, effective removal technology is desired. The possibility that a high concentration and a large amount of Ichidani carbon is released into the air is mainly during emergencies, and is caused by fire, gas leakage, incomplete combustion, and the like. There is a gas mask as a carbon monoxide removal technology corresponding to these, and hopcalite is used for the absorber for the carbon monoxide removal. Hopcalite is described as both a catalyst and an absorbent, but the following disadvantages are known.

1) Only effective for high concentrations of carbon monoxide.

2) Because it has a short life, it can be used only once as a gas mask.

3) Since the activity is lost due to moisture, it can be used only immediately after opening (for this reason, the gas mask is used in combination with a hygroscopic agent).

In recent years, the need to remove carbon monoxide generated in living spaces during normal times has been increasing. In this case, the sources of carbon monoxide include smoking and exhaust gas from automobiles, and the problem arises when carbon monoxide derived therefrom diffuses (or invades) indoors and in enclosed spaces such as automobiles. It becomes. In all cases, the concentration at the source is as high as one percent, but if it diffuses into the air through ventilation, the concentration will be low and ultimately it will be necessary to keep it below the working environment standard of 50ΡΡΙΠ. In areas where ventilation is difficult or near It is necessary to remove carbon dioxide, but it has been reported that conventional air purifiers have a very low carbon monoxide removal effect. This is because in the prior art, there was no catalyst or adsorbent effective for removing carbon monoxide over a wide concentration range from low to high.

Hopcalite is composed of oxides only and is effective in removing high concentrations of carbon monoxide, but not in removing low concentrations of carbon monoxide.

There is also a method in which a noble metal catalyst such as platinum is used at around room temperature.However, noble metal catalysts have catalytic activity at low concentrations, but at high concentrations, self-poisoning occurs due to strong adsorption of carbon monoxide to the noble metal surface. It is immediately deactivated.

In addition, the catalyst in which gold nanoparticles were supported on the oxide surface (hereinafter referred to as “gold nanoparticle catalyst” for simplicity) was obtained by bubbling gas (4.2% steam concentration) by humidification. It has been reported that carbon monoxide can be oxidized and removed in a wide concentration range from 20 to OOOOppm under laboratory conditions at room temperature (at 30) using C0 + 0 ₂ + N ₂ ) (M. Haruta) , "Catalytic Science and Technology", Kodansha, 1991, Vol. 1, pp. 331-334. If humidification is achieved by publishing, It has also been reported that the reaction is greatly accelerated as compared to the case using a dry cylinder gas.

However, low concentrations of carbon monoxide, when carbon dioxide and the concentration of both water vapor is high relative to the concentration of carbon monoxide _{(e.g., C0: 50ppm, CO 2:} 7000ppm, H 2 0: 1. 3¾) Reported that the activity of the gold nanoparticle catalyst was also significantly degraded during the reaction (G. Slinivas et al., “Studies in Surface Sc ience and Catalys is, see Elsevier Sciences, The Netherlands, 1996, Vol. 101, pp. 427-433.) According to the report, the degree of degradation depends on the type of carrier oxide, The cause of this is presumed to be poisoning due to the accumulation of carboxylate or carbonate species generated during the reaction on the catalyst surface.

In addition, Japanese Patent Application Laid-Open No. 2000-3341453 describes that by irradiating the gold nanoparticle catalyst with light, the oxidation reaction of carbon monoxide can be promoted as compared with non-irradiation. . Japanese Unexamined Patent Publication No. 2000-313334 discloses that air It is described that the catalyst can be regenerated by irradiating light to a gold nanoparticle catalyst whose activity has been reduced by such contaminants. Disclosure of the invention

The present inventors studied the applicability of the gold nanoparticle catalyst in the living environment needs of carbon monoxide removal in normal times as described above. Experiments on the oxidative removal of carbon monoxide confirmed that the gold nanoparticle media worked effectively over a wide concentration range, and found the following two problems related to the deterioration of the catalyst. That is,

1) As reported previously, a decrease in activity during the reaction is observed. 2) Although there is no point in the previous reports, the gold nanoparticle catalyst is stable when sealed in a sample bottle and shows high activity immediately after opening, but it takes a long time after opening. By simply exposing to air, a decrease in activity is observed before the reaction.

In the catalyst activity test in the laboratory, the catalyst is usually used after reactivation by heat treatment, etc., and in the above case, it has been confirmed that the sample after activity degradation can recover its activity by heat treatment. .

However, especially when considering the use of the catalyst in the purification of living environment, it is not desirable to provide a heat treatment section not only from the viewpoint of energy saving but also from the viewpoint of the price and size of the apparatus. Therefore, there is a strong demand for the development of a catalyst technology that can maintain high activity at room temperature for a long time without heating during the pretreatment as well as during the reaction.

That is, an object of the present invention is to remove carbon monoxide in a gas, which can remove carbon monoxide in a wide range of concentrations from low to high, and can maintain high activity at room temperature for a long time. An object of the present invention is to provide a catalyst composite, a carbon composite and a method for removing carbon monoxide using the same.

The present inventor has conducted intensive studies in view of the problems of the prior art as described above and the problems discovered by the inventors, and as a result, has found that in the oxidative removal of carbon monoxide in a gas (particularly, real air). The alkaline porous material powder is allowed to coexist with a catalyst in which nano-sized gold particles are supported on a metal oxide (hereinafter referred to as “gold nanoparticle catalyst”). The present inventors have found that the activity degradation before and during the reaction can be suppressed as compared with the case where the reaction is not performed, and have completed the present invention.

That is, the present invention provides the following technology.

Item 1. A catalyst composite for carbon monoxide removal comprising a gold nanoparticle catalyst in which gold particles having an average particle diameter of 25 nm or less are supported on a metal oxide, and a porous porous material.

Item 2 The catalyst composite according to Item 1, wherein the gold nanoparticle catalyst is mixed with a porous porous material.

Item 3. The catalyst composite according to Item 1, wherein the gold nanoparticle catalyst is supported on an alkaline porous material.

Item 4.A term in which an alkaline porous material is arranged before, or both before and after the gold nanoparticle catalyst, so that the gas containing carbon monoxide once passes through the alkaline porous material and then contacts the gold nanoparticle catalyst. 2. The catalyst composite according to 1.

Item 5. The catalyst composite according to any one of Items 1 to 4, wherein the alkaline porous body is one in which an alkali component is supported on the surface of the porous body.

Item 6. A group consisting of activated carbon, carbon black, zeolite, silica, alumina, iron oxide, and titanium oxide having a specific surface area of about 10 m ² / g or more measured by a nitrogen adsorption method (BET method). Item 6. The catalyst complex according to item 5, which is at least one member selected from the group consisting of:

Item 7. The catalyst composite according to item 6, wherein the porous body is activated carbon having a specific surface area of about 10 m ² / g or more measured by a nitrogen adsorption method (BET method).

Item 8 The item in Item 5 in which the alkali metal component is at least one selected from the group consisting of oxides, hydroxides, and carbonates of aluminum metals or earth metal metals in the periodic table. A catalyst composite according to claim 1.

Item 9 An air purification filter comprising the catalyst composite according to any one of Items 1 to 8, which has any one of a honeycomb shape, a bead shape, and a fibrous shape.

Item 10. A carbon monoxide removing device equipped with the air purification filter according to Item 9.

Item 11. A method for removing carbon monoxide in a gas, comprising using the catalyst composite according to any one of Items 1 to 8 in a temperature range of 70 to 350.

Item 12. The catalyst composite according to any one of Items 1 to 8 is used in a temperature range of 70 to 350. A method for removing carbon monoxide in a gas, which is used under light irradiation conditions. The present invention will be described in detail below.

Alkaline porous body

The porous body used in the present invention may be a porous body carrying an alkaline component or a porous body which exhibits alkalinity by itself.

When the porous material is a porous material carrying a component, the porous material (porous mater als) has a specific surface area measured by a nitrogen adsorption method (BET method). Is about 10ffl ² / g or more, preferably about 30mVg or more. As long as it is a porous material that meets this definition, it may be in any form such as powder, fiber, sponge, or honeycomb, regardless of its appearance (macrostructure). Specific examples of the porous body include activated carbon, force pump rack, zeolite, silica, alumina, iron oxide, and titanium oxide.

Examples of the alkali component to be carried include oxides of alkali metals or alkaline earth metals in the periodic table, 7K oxides, carbonates, and the like, and those containing at least one selected from the group consisting of these. No. Specific examples alkali component, MgO, CaO, Mg (0H ) 2, Ca (0H) 2, Na 2 C0 3, K 2 C0 3 and the like. Among them, in terms of C0 ₂ adsorptive in existence under _{_{_{moisture, Na 2 C0 3, K 2}}} C0 3 and the like are preferable.

The above-described porous porous material having the porous component supported on the surface of the porous material is described, for example, in the literature (H. Hayashi et al, Ind. Eng. Chem. Res., 1998, 37, 185). -191). That is, about 10 g of a porous material is added to about 30 ml of an aqueous solution of an alkali component of about 2 to 20%, and then τΚ is evaporated to dryness. If necessary, add water again, stir and evaporate the water to dryness. Then, it is dried in an inert gas (eg, helium, nitrogen) at about 100 to 200 for about 1 to 24 hours. As a result, a porous body containing about 5 to 50% by weight of an alkali component is produced.

Also, if Al force Li porous body is a porous body that exhibits itself al force re resistance, the nitrogen adsorption method specific surface area measured by (BET method) than about 1 O MVG, preferably 3 0 m ² / g or more is used. As a specific example, a high-purity ultra-fine powder magnesium (Ube Materials Co., Ltd.) is exemplified. The form of the porous porous body can be appropriately selected according to the purpose of use, and examples thereof include powder, granules, pellets, and honeycomb-like ones. When mixed and used, powder is preferred from the viewpoint of uniform mixing. When the shape is a powder, the average particle size is about 0.05 to: L mm, preferably about 0.05 to 0.2 mm.

If the porous body is commercially available as a porous body containing an alkaline component, it may be used as it is. For example, there is alkali-impregnated activated carbon (for adsorbing acidic gas). Specific examples include granular Shirasagi activated carbon GHxUG (manufactured by Takeda Pharmaceutical Co., Ltd .; “Shirasagi” is a trademark of Takeda Pharmaceutical Co., Ltd .; the same shall apply hereinafter). This alkaline porous body may be used as a mixture with the alkaline porous body described above.

Gold nanoparticle catalyst

As described above, the gold nanoparticle catalyst used in the present invention is a catalyst having a structure in which gold particles are supported on a metal oxide carrier. Specifically, it is a catalyst having a structure in which nano-sized gold particles are uniformly supported on the surface of a metal oxide carrier. The average particle size of the gold particles is preferably from about the size of gold atoms to about 25 nm or less, and more preferably from about l to 10 nm. The average particle size of the gold particles is a value measured by transmission electron microscopy. Examples of metal oxides that carry gold particles include zinc oxide, iron oxide, copper oxide, lanthanum oxide, titanium oxide, cobalt oxide, zirconium oxide, magnesium oxide, oxidized beryllium, nickel oxide, oxidized chrome. Metal oxides of single metals selected from the group consisting of: scandium oxide, cadmium oxide, indium oxide, tin oxide, manganese oxide, vanadium oxide, cerium oxide, aluminum oxide, and silicon oxide; zinc; Two types selected from the group consisting of iron, copper, lanthanum, titanium, cobalt, zirconium, magnesium, beryllium, nickel, chromium, scandium, cadmium, indium, tin, manganese, vanadium, cerium, aluminum, and gaysen Use of the above-mentioned composite oxide It can be. The above-described metal oxides and composite oxides of a single metal can be used as a mixture if necessary.

The content of gold in the gold nanoparticle catalyst may be about 0.1 to 30% by weight based on the total amount of the gold nanoparticle catalyst, and from the viewpoint of activity per amount of gold used, 0.1 to 30% by weight. It is preferred to be about 10% by weight.

The form of the gold nanoparticle catalyst can be appropriately selected according to the purpose of use, and examples thereof include powder, granule, pellet, and honeycomb. Among them, when used in combination with an alkaline porous material, a powdery material is preferred from the viewpoint of uniform mixing. When the shape is powder, the average particle size is about 0.05 to 1 s, preferably about 0.05 to 2 s.

The specific surface area of the gold nanoparticle catalyst is usually about 1 to 800 m ² / g, preferably about 5 to 30 Om ² / g, as measured by the BET method.

As a method for supporting gold as nano-sized particles on a metal oxide, the following known methods can be employed.

• Co-precipitation method (JP-A-60-238148)

• Precipitation and precipitation method (JP-A-3-97623, etc.)

• Colloid mixing method (Tsubota S. et al., Catal. Lett., 56 (1998) 131) • Gas phase grafting method (JP-A-9-122478)

'Liquid phase grafting method (Okumura M. et al., Chem. Lett., (2000) 396) The following compounds can be mentioned as starting materials. Examples of the gold precursor include compounds that are vaporized by heating, such as a water-soluble compound of gold (for example, chloroauric acid) and an acetyl acetonato complex (for example, a gold acetyl acetonato complex).

Examples of the raw material of the metal oxide include nitrates, sulfates, acetates, and chlorides of various metals. Specific examples include nitrates such as cerium nitrate and zirconium nitrate, sulfates such as titanium sulfate, and chlorides such as cerium chloride, titanium trichloride, and titanium tetrachloride.

After a precipitate is deposited by the known method described above, the precipitate is washed with water and dried. The precipitate may be heat-treated in an oxygen atmosphere or a reducing gas in order to finally bring the gold into a metallic state. The term “in an oxygen atmosphere” refers to an atmosphere under air or a mixed gas obtained by diluting oxygen with nitrogen, helium, argon, or the like. As the reducing gas, for example, a hydrogen gas or a carbon monoxide gas of about 1 to 10 V o 1% diluted with a nitrogen gas can be used. The heat treatment temperature may be appropriately selected from a range of known reduction conditions, and is usually preferably from room temperature to about 600. To obtain stable and fine gold particles Is more preferably about 200 to 400. The heat treatment time is preferably, for example, about 1 to 12 hours.

Catalyst composite for removing carbon monoxide and method for producing the same

The catalyst composite of the present invention contains the above-described gold nanoparticle catalyst (gold nanoparticles / metal oxide) and an alkaline porous body. Specific examples include a catalyst composite obtained by mixing a gold nanoparticle catalyst and an alkaline porous material, a catalyst composite obtained by supporting a gold nanoparticle catalyst on an alkaline porous material, and the like.

In the case of a catalyst composite obtained by mixing a gold nanoparticle catalyst and an alkaline porous material, for example, a powdery gold nanoparticle catalyst and a powdery alkaline porous material are mixed by a known method. Can be manufactured. For example, stirring and mixing may be performed using a mortar, a mixer, or the like.

In the case of a catalyst composite in which a gold nanoparticle catalyst is supported on a porous porous material, it can be prepared by the following procedure according to the above-described various methods for preparing a gold nanoparticle catalyst.

A. When using the coprecipitation method

(A1) A gold nanoparticle catalyst containing a porous material is prepared by using a coprecipitation method in the presence of the porous material.

(A2) An alkali component is supported on the product obtained in (A1) using an impregnation method or the like. If the porous body is alkaline and retains alkalinity even after washing, the procedure (A2) can be omitted.

B. When using the precipitation / sedimentation method, colloid mixing method, gas phase grafting method, and liquid phase grafting method

(B1) The metal oxide component of the gold nanoparticle catalyst is supported on the surface of the porous body by an impregnation method or the like. (B2) A gold component is supported on the material obtained in (B1) using a precipitation and precipitation method, a colloid mixing method, a gas phase grafting method, a liquid phase grafting method, or the like.

An alkali component is supported on the product obtained in (B3MB2) using an impregnation method or the like. If the porous body is alkaline and retains alkalinity even after the operations (Bl) and (B2), the procedure of (B3) can be omitted.

When the porous material is a carbon material such as activated carbon, it is particularly important to note that during the preparation, the gold solution and the carbon-based porous material (eg, activated carbon, carbon black, etc.) If it does, gold becomes coarse particles due to the reduction action of carbon. For this reason, for example, when a metal oxide is supported on the surface of a carbon-based porous body and gold is to be further supported by a precipitation method, contact of the exposed carbon powder surface with the gold solution causes It becomes difficult to convert the particles into nanoparticle. Therefore, as a catalyst preparation method in such a case, it is preferable to employ either a colloid mixing method without using a gold solution in an ionic state or a gas phase grafting method.

In addition to the above, the catalyst composite of the present invention may be provided in front of, or before and after the gold nanoparticle medium so that the carbon monoxide-containing air once contacts the gold nanoparticle medium after passing through the alkaline porous body. And those in which an alkaline porous body is disposed. Specifically, a layer containing an alkaline porous body and a layer containing a gold nanoparticle catalyst are sequentially provided in a flow path through which carbon monoxide-containing air passes, or a layer containing an alkaline porous body, A catalyst composite in which a layer containing a nanoparticle catalyst and a layer containing a porous porous material are sequentially provided.

The use ratio of the gold nanoparticle catalyst and the alkaline porous material in the catalyst composite of the present invention may be arbitrary. However, in order to obtain a clear carbon monoxide removal effect, the amount of the alkaline porous material must be equal to or more than that of the gold nanoparticle catalyst. It is preferred to use a body. Specifically, the weight ratio of the gold nanoparticle catalyst to the alkaline porous material may be about 1 ::! To 1: 100. The catalyst composite of the present invention can be used in any form according to the purpose of use. For example, any form such as powder, sponge, bead, 82 cam, and fiber may be used. In particular, when used as a filter through which air that needs to be treated, such as an air purification filter, is used, use any of bead, honeycomb, and fiber forms that have less resistance to air flow than powder. Is preferred.

A known method may be used to form the catalyst composite of the present invention having these forms. For example, a bead, honeycomb, or fibrous form can be obtained by fixing a mixed powder of a gold nanoparticle catalyst and an alkaline porous body to the surface of various beads, honeycomb, or nonwoven fabric using a binder or the like. It can be. For example, in the case of a catalyst composite in which a gold nanoparticle catalyst is supported on an alkaline porous material, beads, a honeycomb, or a fibrous The above-mentioned form can be obtained by applying the preparation procedure of the above A and B using a base material.

Carbon monoxide removal method

The removal of carbon monoxide using the catalyst composite of the present invention is carried out by bringing air requiring removal of carbon monoxide into contact with the catalyst composite. That is, it reacts carbon monoxide in the air with oxygen in the air to convert it into carbon dioxide, thereby removing carbon monoxide.

The concentration of carbon monoxide in the air to be treated can be any chemical reaction equivalent to the oxygen concentration in the air (usually 20¾ for air) (40% or less for 20% oxygen). By using the catalyst composite of the present invention, carbon monoxide can be removed with high efficiency even for a gas (particularly, air) containing a low concentration of carbon monoxide of several PPD1. The use temperature of the body is not particularly limited as long as it is a gold nanoparticle catalyst operating temperature of −70 or more.In general, the higher the use temperature, the faster the carbon monoxide oxidation reaction rate. In order to suppress agglomeration of particles, it is preferable that the temperature is not more than 350. From the viewpoint of energy-saving use that does not require heating, use in a temperature range from room temperature to 100 ° C is desired. .

The removal of carbon monoxide using the catalyst composite of the present invention is carried out in the above temperature range using a gold nanoparticle catalyst as a “heat” catalyst (meaning that it is not a catalyst). It may be carried out under light irradiation conditions.

By irradiating the gold nanoparticle catalyst used in the present invention with light, the oxidation reaction of carbon monoxide can be promoted as compared with the non-irradiation. The gold nanoparticle catalyst, whose activity has been reduced by contaminants present in the air, can be regenerated by light irradiation. Therefore, the effect of promoting the oxidation reaction can be expected while the gold nanoparticle catalyst is in contact with the carbon monoxide gas, and the catalyst regeneration effect by light irradiation can be exerted during the other period. Therefore, when the catalyst composite of the present invention including the gold nanoparticle catalyst and the alkali porous material is irradiated with light, in any case where carbon monoxide contacts the catalyst surface intermittently or continuously, A higher carbon monoxide removal effect can be maintained for a longer period than without light irradiation.

The wavelength of the irradiating light depends mainly on the expected effect of promoting the oxidation reaction of carbon monoxide. May be appropriately set depending on whether the reproduction effect is expected. Generally, by using light in a wavelength range of about 1 to 1000 thighs, more preferably about 200 to 700 mn, both effects of promoting the reaction of the nanoparticle catalyst and regenerating it can be obtained.

In the case of light irradiation, a gold nanoparticle catalyst containing a metal oxide having any of the above-described compositions can be used. In particular, when the above-described photoreaction promoting effect is obtained, titania, alumina, silica, zirconium, zinc oxide, ceria, manganese oxide, magnesia, and the like are preferable as the metal of the metal oxide component of the gold nanoparticle catalyst. , Titania, alumina, silica and the like are particularly preferred.

The present invention also provides a carbon monoxide removing device provided with the above-mentioned air purification filter. The carbon monoxide removing device includes the above-described air purifying filter and, if necessary, a light source required for light irradiation. Any light source may be used as long as it has a light wavelength capable of promoting the oxidation reaction of carbon monoxide, such as natural light, high-pressure mercury lamp, low-pressure mercury lamp, black light, excimer laser, deuterium lamp, xenon lamp, etc. Can be adopted.

The mechanism of the degradation of the activity of the gold nanoparticle catalyst has not been completely elucidated at present, but is described in the literature (NM Gupta, et al., Gold Building et in, 34, pp. 120-128 (2001)). Based on the description, the following mechanism can be considered.

1) The surface of the metal oxide carrier reacts with water in the air to form hydroxyl groups on the surface, and the surface becomes highly active.

Fe-0-Fe + H ₂₀ → 2Fe-0H

2) the surface hydroxyl groups react slowly with C0 _2, bicarbonate species (inert) is deteriorated occurs.

_{Fe-OH + C0 2 → Fe} -0- (00) - OH

That is, it is considered that both moisture and carbon dioxide are involved in the air and deteriorate. In the catalyst composite of the present invention, it is considered that the alkaline porous body present together with the gold nanoparticle catalyst appropriately absorbs carbon dioxide and moisture, thereby suppressing the activity deterioration of the gold nanoparticle catalyst.

In addition, various trace organic substances (V0C) and whey components (H ₂ S, etc.) are present in the air in a room or the like, and these may also cause deterioration of the gold nanoparticle catalyst. But, When the porous carbon material contains activated carbon, the activated carbon also has an effect of adsorbing and removing the component causing the deterioration of the gold nanoparticle catalyst, so that the effect of suppressing the deterioration of the gold nanoparticle catalyst is further enhanced.

The catalyst composite of the present invention is widely used for removing carbon dioxide. For example, air conditioning of air conditioners (air purifiers, air conditioners, smoke separators, etc.) indoors and in automobiles Filter 1; Filling of fire and gas masks; Filtration of CO from raw material gas used in chemical factories, etc. (1) A filter for removing CO from exhaust gas from automobiles, engines, etc .; It is suitably used as a filter for removing CO in the hydrogen production process by fuel reforming of fuel cells. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph showing the change over time in the concentration of carbon monoxide in the catalyst of Example 1.

FIG. 2 is a graph showing the time-lapse of the catalysts of Example 2 and Comparative Example 1 left in air and the removal rate of carbon monoxide with time.

FIG. 3 is a graph showing the time elapsed from the start of the first reaction and the carbon monoxide removal rate with time in the reaction repetition test using the catalysts of Example 4 and Comparative Example 5. BEST MODE FOR CARRYING OUT THE INVENTION

Next, the present description will be further described with reference to examples. However, the present invention is not limited to the following examples unless departing from the gist thereof.

[Example 1]

In the present embodiment shows an example of using the gold Z iron oxide catalyst was mixed with K ₂ C0 ₃ on activated charcoal.

(1) Preparation of gold nanoparticle catalyst (gold iron oxide catalyst)

Chloroauric acid _{[HA u C l 4 · 4} Η 2 〇] 2.7 mmol and iron _{_{[F e (N0 3) 3}} · 9 H 2 0] dissolved 1 2 5 mmol 3 2 0 ml of distilled water And heated to 70 (Solution A). Then, sodium carbonate [N a ₂ C_〇 _3] 2 3 0 mmol dissolved in 1 8 0 ml of distilled water and heated to 70 (B solution). Next, solution A is dropped into solution B, and 70 For 1 hour. Thereafter, the coprecipitate obtained by cooling to room temperature was sufficiently washed with water and dried. Finally, by firing in air 4 0 0 4 hours, gold / iron oxide catalyst [A u Roh F e ₂ 〇 _3, amount of metal supported 5 wt%] was obtained. The obtained gold nanoparticle catalyst was sealed and stored in a screw bottle.

(2) Preparation of alkaline porous body (K ₂ C0 ₃ on charcoal)

Preparation of K ₂ C0 ₃ carrying activated carbon, literature (H. Hayashi et al, Ind. Eng. Chem. Res., 1998, 37, 185-191) was carried out as follows according to the description of. First, dissolve put K ₂ C0 ₃ powder and water 3 Om l of 3. Og the flask was further added activated carbon 10g. The water was evaporated using an evaporator and evaporated to dryness. Ze lightly mixed by adding 1 5 ml again water, by discarding excess water, to remove excess K ₂ C0 ₃ which causes blocking the pores of the activated carbon. After evaporating the water at the rotary evaporator and drying it, it was dried at 150 in a stream of air. According to the literature, it contains 1 5 wt% of K ₂ C0 ₃ If prepared in this condition.

(3) Mixing of gold nanoparticle catalyst and alkaline porous material

Taking out the catalyst from the screw bottle immediately prior to the active test, a 0. 1 g of gold nanoparticle catalyst and mixed well until uniform using K ₂ C0 ₃ on activated carbon 1. O g and mortar. Subsequently, using the obtained mixed powder, the activity against the carbon monoxide oxidation reaction was examined by the following method.

(4) Activity measurement method

The above mixed powder was spread on a watch glass and placed on the bottom of a glass desiccant overnight having an internal volume of about 300 ml (volume excluding the volume of the installed object in the desiccant overnight). The lid was closed overnight, and 0.3 ml of carbon monoxide gas was injected from the inlet with a septum at the top of the lid using a gas tight syringe. The initial concentration of carbon monoxide at the time of injection is 100 ppm. In the desicca, a fan is installed to allow air to circulate sufficiently, so that when air containing carbon monoxide touches the catalyst and a reaction occurs, carbon monoxide is converted to carbon dioxide. Is done. The changes in the concentrations of carbon monoxide and carbon dioxide immediately after the injection were measured to follow the catalytic reaction. The carbon monoxide in the desicca was measured by a potentiostatic carbon monoxide gas sensor installed in the desicca, and the carbon dioxide concentration was measured by a non-dispersive infrared carbon dioxide gas sensor in the form of external circulation. (5) Measurement of initial activity

Figure 1 shows the time variation of carbon monoxide concentration due to the catalytic reaction. Carbon monoxide decreased with time ω due to catalytic reaction immediately after the injection, and became completely zero within 20 minutes. In order to compare the catalytic activity, after a certain period of time (for example, 10 minutes, t = 10), the carbon monoxide removal rate (C _{t = l} ) is determined by the following equation.

C _{l = 10} (¾) = ([CO] _{t = 0-} [CO]) I [CO] _{t = 0} X 100

Here, [(: 0 is the carbon monoxide concentration immediately after the injection, and [CO.] Is the carbon monoxide concentration 10 minutes after the injection. In the case of FIG. 1, the C0 concentration after 10 minutes is 2 ppm, so that _{Cl = 1} . It is 98¾ (Table 1).

(6) Activity measurement after leaving in air

After the initial activity test Bok, a total of dishes when carrying the mixed powder of the gold nanoparticle catalyst and K ₂ C0 ₃ on activated carbon was removed from desiccator Isseki, it was allowed to stand in air. When the activity test was performed again three days later, C _{t = 1} . = 64¾ (Table 1).

[Example 2]

0.1 g of alkali-impregnated activated carbon (granular Shirasagi activated carbon GHxUG; manufactured by Takeda Pharmaceutical Co., Ltd.) was used as the alkaline porous material, and mixed with 0.1 g of gold iron oxide. The procedure was carried out in the same manner as in Example 1 except that the activity was measured after standing for 6 days without performing the activity test immediately after mixing. The results were as shown in Table 1, _{Ct = 1} after 6 days. = 69%, which was higher than that of Example 1.

[Comparative Example 1]

The activity test was carried out under the same conditions as in Example 1 using only the gold-Z iron oxide catalyst 0.1 lg without mixing the porous aluminum with the gold / iron oxide catalyst prepared at the same time as in Example 1. After the removal from the sample bottle, _{Cl = l} . = 100%, but after 3 days left C _{t = l} . = 26% (Table 1). Fig. 2 shows the state of deterioration with respect to the number of days left, in comparison with the results of Examples 1 and 2. From these results, it is recognized that the degree of deterioration is greater than when the alkaline porous body is mixed.

[Comparative Example 2]

As used K ₂ C0 ₃ powder 0.1 5 g as alkali powder not porous body, gold iron oxide catalyst 0.1 except mixed with g was carried out in the same manner as in Example 1. The results are shown in Table 1. K ₂ C0 ₃ on activated carbon 1 g used in Example 1 (1 from the literature 5 wt% of K ₂ C0 ₃ in charge Although it believed to contain K ₂ C0 ₃ Preparation) Equal amounts of at lifting of conditions, the same in the case of comparison with single use of Al force Li powder containing no porous body is not observed inhibitory effect of degradation .

[Comparative Example 3]

The procedure was performed in the same manner as in Example 1 except that 0.1 g of silica gel was used for the mixture. Table 1 shows the results. Even if the mixture is a porous material, when the mixture does not have an adhesive force, the effect of suppressing inferiority is not recognized.

[Example 3]

In this embodiment, an example in which a titanium oxide catalyst is mixed with an alkali-impregnated activated carbon is used.

It was dissolve chloroauric acid _{_{[HAuC 1 4 · 4H 2 0}} ] 473 mmol of distilled water 75 Om 1, was adjusted to pH 7 by dropwise addition of N A_〇_H aqueous solution was heated to 70. To this, 3.Og of titanium oxide powder was added, and the mixture was stirred at 7 for 1 hour. Thereafter, the film was sufficiently washed with distilled water The cooled precipitate to room temperature, dried by Rukoto be calcined 4 hours in air 400, gold / titanium oxide catalyst [AuZT i0 _2, gold supported amount 3 wt% ]. The obtained gold nanoparticle catalyst was sealed and stored in a screw bottle until immediately before use. 0.1 g of the obtained gold oxide titanium catalyst and 0.1 g of alkali-impregnated activated carbon (granular Shirasagi activated carbon GHxUG; manufactured by Takeda Pharmaceutical Co., Ltd.) were mixed in the same manner as in Example 1, and mixed in the same manner as in Example 1. An activity test was performed. Table 1 shows the results.

[Comparative Example 4]

The procedure was performed in the same manner as in Example 3 except that the mixture was not added to 0.1 g of the gold / zinc titanium oxide catalyst. Table 1 shows the results. In the case of the gold titanium oxide catalyst, even if used as it is, the activity deterioration is smaller than that of the gold zirconium oxide. However, the degree of deterioration is clearly larger than that in the case of adding activated carbon impregnated with aluminum oxide. table 1

[Example 4]

In the same manner as in Example 3, a mixture of 0.1 g of titanium oxide titanium oxide and 0.1 g of activated carbon impregnated with alkali was obtained. In the same manner as in Example 1, an initial activity test (first time) for air containing carbon monoxide at 10 O ppm in the desiccator was performed until the carbon monoxide concentration became zero. After the first activity measurement, the lid was opened for overnight in Deshike, ventilated with a fan for 5 minutes, the lid was closed, and 100 pm of carbon monoxide was injected again to perform an activity test (second time). In this way, the activity test was repeated up to the fourth time, and after the fourth time, the catalyst was once taken out and exposed to air for 2 hours, and then the catalyst was returned to the desiccator and the fifth activity test was performed. Table 2 and Fig. 3 show changes in the activity of the gold nanoparticle catalyst obtained in the above-described reaction repetition test. The first time _{Cl = 1} . The initial activity, which was 97%, was Ct _{= 1 ()} = 95% at the fifth time, and the activity was less deteriorated than the comparative example described later.

[Comparative Example 5]

A reaction repetition test was performed in the same manner as in Example 4 using only 0.1 g of the titanium gold oxide catalyst obtained in the same manner as in Example 3. As shown in Table 2 and FIG. 3, the results show that the activity was significantly deteriorated as compared with the case of Example 4. Table 2

The publicly known documents described in this specification are incorporated by reference for industrial applicability.

The catalyst composite for removing carbon monoxide of the present invention has a high activity of removing carbon monoxide, maintains its activity even in air for a long time, and has little deterioration. In addition, the catalyst complex of the present invention does not necessarily require a catalyst activation treatment by reheating because the activity of removing carbon monoxide is maintained for a long time, and the apparatus for removing carbon monoxide is inexpensive and compact. I can dagger. Therefore, the catalyst composite of the present invention can be used for a wide range of uses for removing carbon monoxide. Furthermore, by using the catalyst composite of the present invention under light irradiation conditions, a high carbon monoxide removal effect can be maintained for a longer period of time.

Claims

The scope of the claims

I. A carbon monoxide removal catalyst composite comprising a gold nanoparticle catalyst in which gold particles having an average particle diameter of 25 nm or less are supported on a metal oxide, and a porous porous material.

2. The catalyst composite according to claim 1, wherein the catalyst is a mixture of a gold nanoparticle catalyst and a porous porous material.

3. The catalyst composite according to claim 1, wherein the gold nanoparticle catalyst is supported on an alkaline porous material.

4. Place the alkaline porous material before, or both before and after the gold nanoparticle catalyst, so that the carbon monoxide-containing gas once contacts the gold nanoparticle catalyst after passing through the porous porous material. The catalyst composite according to claim 1, wherein the catalyst composite is arranged.

5. The catalyst composite according to any one of claims 1 to 4, wherein the alkaline porous body is one in which an alkali component is supported on the surface of the porous body.

6. A group consisting of activated carbon, activated carbon, zeolite, silica, alumina, iron oxide, and titanium oxide having a specific surface area of about 1 OmVg or more as measured by a nitrogen adsorption method (BET method). The catalyst composite according to claim 5, which is at least one member selected from the group consisting of:

7. The catalyst composite according to claim 6, wherein the porous body is activated carbon having a specific surface area of about 10 m ² / g or more measured by a nitrogen adsorption method (BET method).

8. The scope of claim 1, wherein the alkali metal component is at least one selected from the group consisting of oxides, hydroxides, and carbonates of aluminum metal or earth metal of the periodic table. 6. The catalyst composite according to the fifth aspect.

9. An air purification filter comprising the catalyst composite according to any one of claims 1 to 8, which has any of a honeycomb shape, a bead shape, and a fibrous shape.

10. A carbon monoxide removing device provided with the air purification filter according to claim 9.

II. A method for removing carbon monoxide in a gas, comprising using the catalyst composite according to any one of claims 1 to 8 in a temperature range of -70 to 35 (TC).

1 2. The catalyst composite according to any one of claims 1 to 8 A method for removing carbon monoxide from a gas, wherein the method is used under light irradiation conditions in a temperature range of 1 to 3 hours.