JPH08332378A - Deodorizing photocatalytical activated carbon and production thereof - Google Patents

Abstract

PURPOSE: To obtain deodorizing photocatalytical activated carbon having high gas adsorbing capacity and a wide adsorption spectrum, also equipped photocatalytical function and excellent in processability by uniformly mixing activated carbon precursor org. matter and a Ti-containing soln. and subsequently baking the resulting mixture to carbonize and activate the same to form titanium oxide supported activated carbon. CONSTITUTION: Deodorizing photocatalitical activated carbon based on titanium oxide supported activated carbon by uniformly mixing activated carbon precursor org. matter and a Ti-containing soln. and subsequently baking the resulting mixture to carbonize and activate the same. As the activated carbon precursor org. matter, any org. substance used as an activated carbon material can be adapted. As a Ti compd., thereis no special limit even if a material capable of being converted to TiO2 is used but titanium tetrachloride is industrially pref. Since supported titanium oxide is uniformly dispersed in activated carbon, this deodorizing photocatalyst has the original high specific surface area of activated carbon and, since this photocatalyst is strongly fixed to an adsorbent, it is excellent in processability even if a binder is not used.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel deodorizing photocatalytic activated carbon and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a deodorizing method for a refrigerator, for example, a method of adsorbing and removing with active carbon, a method of oxidatively decomposing a malodorous component with ozone generated by an ozone generator and an ozone reactor (Japanese Patent Laid-Open No. 61- No. 93381,
Japanese Patent Laid-Open No. 61-205381), a method of oxidatively decomposing a malodorous component by irradiating it with ultraviolet rays using a photocatalyst such as titanium dioxide is known. Among them, the method of adsorptive removal of malodorous components by activated carbon is widely used at present,
There is a limit to the amount of odorous components that can be adsorbed by activated carbon. For example, in a high-concentration odorous component, the adsorption capacity is saturated immediately, and the deodorizing effect can be maintained for a short time. Further, the method of oxidizing a malodorous component by ozone requires a high voltage, and further has a problem that an ozone odor remains after deodorization.

Since the deodorizing method using a photocatalyst can maintain the deodorizing effect for a long period of time, in recent years, it is a deodorizing method which has been particularly attracting attention as a deodorizing agent for refrigerating cycle devices such as refrigerators and air conditioners. Generally, when a photocatalyst is used alone as a deodorant, it is used with an adsorbent having a wide adsorption spectrum such as activated carbon or zeolite because the adsorption capacity is insufficient and the adsorption spectrum is limited. Has been. Examples of the currently known deodorizing method using a photocatalyst include, for example, JP-A-1-189321.
Japanese Patent Laid-Open No. 1-218635 and Japanese Patent Laid-Open No. 1-218635 can be cited. The former discloses a deodorant that forms a photocatalyst layer on the surface of an adsorbent by a photocatalyst immersion impregnation method in which a honeycomb-shaped activated carbon is immersed in a titanium dioxide-based solution, or a deodorant in which a photocatalyst is kneaded in the adsorbent is disclosed. Discloses a method of using a deodorant formed by sintering a mixture containing an adsorbent of activated carbon, alumina and silica and a photocatalyst.

However, any deodorant has a problem in the fixing strength of the photocatalyst particles to the adsorbent. Therefore, fixing with a binder is generally considered, but the use of the binder closes the pores of the adsorbent. However, there is a drawback that the photocatalyst itself decomposes the binder by the photocatalytic action.

In addition, recently, fibrous activated carbon (Activated C) has been used as activated carbon next to granular activated carbon and powdered activated carbon.
arbon Fiber) has been industrialized. It has a fibrous shape with a diameter of 10 to 30 μm, and is largely different from the granular activated carbon in that it is mainly composed of micropores, and this is because the adsorption rate for the adsorbed molecule is fast. The specific surface area has also has high specific surface area of typically 1000 to 2000 ² / g things 2500 m ² / g, and, working from the form of a thin fibrous combines the mechanical properties such as elastic modulus and strength It excels in properties and enables processing into various forms compared to conventional activated carbon.

[0006]

In view of the above facts, the present inventors have earnestly studied the development of a novel activated carbon photocatalyst, and as a result, after the activated carbon precursor organic substance and the Ti-containing solution were mixed and treated, The inventors have completed the present invention by discovering that titanium oxide-supported activated carbon that has been carbonized by calcination and activated has a wide adsorption spectrum, excellent adsorption performance, and high photocatalytic function. That is, an object of the present invention is to provide a novel deodorizing photocatalytic activated carbon and a method for producing the same.

[0007]

The deodorizing photocatalytic activated carbon to be provided by the present invention is characterized in that it contains titanium oxide-supported activated carbon carbonized and activated in the presence of a Ti component as an active ingredient. . Further, the method for producing a deodorizing photocatalytic activated carbon to be provided by the present invention is characterized in that the activated carbon precursor organic substance and the Ti-containing solution are uniformly mixed and treated, then carbonized by firing and activated. And

The deodorizing photocatalyst of the present invention is characterized in that since the supported titanium oxide is uniformly dispersed in the activated carbon, it has a high specific surface area inherent to the activated carbon, and the photocatalyst has high strength as an adsorbent. Since it is fixed to the base, it has excellent workability without using a binder. In particular, in the case of fibrous activated carbon, it can be easily processed into various forms, and many applications can be developed. The deodorizing photocatalytic activated carbon according to the present invention is an activated carbon supporting titanium oxide, but is fundamentally different from the conventional so-called impregnated supporting activated carbon containing adsorbed titanium oxide.

That is, the titanium oxide-supporting activated carbon in the present invention is carbonized and activated in the presence of a Ti component. Here, carbonizing and activating in the presence of a Ti component means that a mixture of an organic compound, which is a precursor of activated carbon, and a Ti compound is carbonized and activated by a conventional method as described below. The titanium oxide produced in the process is evenly present in the activated carbon. In other words, it can be said that titanium oxide is supported at the production stage of activated carbon.

The content of titanium oxide in activated carbon is
Although it is not uniform depending on the production conditions of activated carbon and deodorizing use, etc., it is 0.1 to 30 wt% as Ti, preferably 0.5.
It is in the range of ˜20 wt%. The reason for this is about 0.1 wt.
% Or less, the effect of the photocatalytic action is insufficient. On the other hand, when it is about 30 wt% or more, the physical properties of the activated carbon are deteriorated, for example, the specific surface area is decreased, and when it is fibrous, the elasticity and strength are deteriorated. It is because it shows. In the present invention, in addition to the Ti component, if desired, Cu, Mn, Fe, Co, Ni, Zn, Ag, P may be used according to each application.
It is also possible to support one or more of t, Pd and the like. Further, the activated carbon according to the present invention has an antibacterial property by itself due to the photocatalytic action of the Ti component, but can further exhibit the antibacterial property by supporting the Ag component.

The deodorizing photocatalytic activated carbon according to the present invention may be either a powder or a molded body depending on the purpose of use. The particle size of the powder is not particularly limited, and the molded body may have any shape such as granular, fibrous, and honeycomb body. However, fibrous activated carbon can be said to be the most preferable from the economical point of view.

The adsorbed molecules targeted by the deodorizing photocatalytic activated carbon are not particularly limited, but examples thereof include ammonia, monomethylamine, dimethylamine, trimethylamine, nitrogen compounds such as nitrogen oxides, hydrogen sulfide, dimethyl sulfide, dimethyl disulfide, Various sulfur compounds such as methyl mercaptan and ethyl mercaptan sulfur oxides, aldehydes such as formaldehyde, acetaldehyde and propyl aldehyde, aliphatic hydrocarbons such as acetic acid, butyric acid, valeric acid and isovaleric acid, indoles, skatole, etc. India-
Examples thereof include alcohols such as phenols, phenols, unsaturated hydrocarbons of ethylene, alcohols such as isopropyl alcohol, sewage odor, animal odor, and other organic gases. Deodorization is effectively exerted by decomposition based on photocatalysis.

The method for producing such deodorizing photocatalytic activated carbon is as follows:
It basically consists of a raw material preparation step of uniformly mixing an activated carbon precursor organic substance and a Ti-containing solution, and a step of calcining and activating the raw material mixture thus obtained.

The activated carbon precursor organic substance is not particularly limited, and any organic substance used as a conventionally known activated carbon material can be applied. For example, pheno
Resin, epoxy resin, melamine resin, thermosetting resin such as urea resin, polyacrylonitrile, polyolefin, polyester, polyamide, polyvinyl alcohol
, Starch, cellulose, methylcellulose, rice husk,
One or two kinds of coconut husks, tar ingredients, coal, wood chips, waste tires and the like can be mentioned.

Next, the Ti compound is not particularly limited as long as it can be converted into TiO ₂ by thermal decomposition. Examples thereof include titanium halides such as titanium chloride, titanium bromide, titanium fluoride and titanium iodide, titanium alcoholates such as methyl, ethyl, propyl and butyl, and other organic titanium compounds. Among them, titanium tetrachloride is industrially preferable, and its aqueous solution or a solution state using an organic solvent such as methanol, ethanol, acetone or benzene is used. If necessary, C
u, Mn, Fe, Co, Ni, Zn, Pt, Pd, Ag
There is no problem even if a solution containing a metal ion such as As these compounds, nitrates, chlorides, acetates and the like are preferable, and they are used as an aqueous solution thereof or in a solution state using an organic solvent.

These raw materials are mixed in a desired container to obtain a uniform raw material mixture. Therefore, it is particularly desirable to dissolve and mix the raw materials and the like in a desired solvent for homogenization, but in a heterogeneous raw material that does not dissolve in the desired solvent, for example, after dipping or adding a Ti solution to a carbonized material, Mix well while stirring and adsorb and impregnate. Then, after the solvent is separated and removed, the obtained formulation is subjected to carbonization and activation treatment by a conventional method to obtain activated carbon. In this case, the activated carbon fiber is preferably carbonized and activated after spinning the raw material mixture.

The carbonization conditions are not particularly limited, and may be 600 to 600 in a non-oxygen gas stream such as nitrogen gas.
It is carried out by firing at a temperature of 1000 ° C., and in the present invention, it is not necessary to take a means different from the usual method.
Also, the activation conditions are not particularly limited, and it is not necessary to take a method different from the usual method. For example, in the case of water vapor or carbon dioxide gas using nitrogen gas as the carrier gas, 70
0-1000 ℃, 400-700 ℃ in case of oxygen gas
The treatment is carried out at the temperature of.

Ti supported by this activation step is
Although the detailed mechanism of what form it exists in is not clear, it appears as titanium dioxide on the pore surface of activated carbon, and when ultraviolet rays are irradiated, electrons in the charge band absorb the ultraviolet rays and are excited in the conduction band. The holes in the charge band generated there react with the hydroxyl groups (OH groups) on the catalyst surface, and the electrons excited in the conduction band react with oxygen (O) to obtain highly active OH radicals, O radicals, O ^-2 occurs, which is presumed to oxidatively decompose the compound to be oxidized.

The deodorizing photocatalytic activated carbon according to the present invention can naturally be used in all fields used as a deodorizing agent utilizing a conventional photocatalytic mechanism, but particularly, removal of thin pollutant gas or high level pollution. It can be effectively applied to fields where gas removal cannot be dealt with.

[0020]

The deodorizing photocatalytic activated carbon according to the present invention contains Ti-supporting activated carbon obtained by carbonizing and activating an organic substance containing a Ti compound as an active ingredient. Therefore, unlike the conventional method in which a Ti compound is impregnated on activated carbon, the supported Ti component is uniformly present in the activated carbon and has a high specific surface area which is a characteristic of activated carbon. . That is, the activated carbon precursor and the Ti compound are particularly preferably liquid-
It is based on preparing activated carbon with a liquid-mixed homogeneous starting compound. At the carbonization stage by calcination, the Ti compound is converted into TiO ₂ , and its fine particles are present in carbon. Then, even if activated carbon is activated by activation treatment, the fine particles are different from the impregnated type and have fine pores unique to activated carbon. Does not block. In particular, the fibrous form can be processed into various forms, and due to its high functionality, it can be used for various purposes. The activated carbon according to the present invention has a high adsorption capacity and a wide adsorption spectrum as compared with the case where a photocatalyst such as titanium dioxide is used alone, and at the same time, has a photocatalytic function based on the supported fine TiO ₂ particles. Therefore, it has an excellent deodorizing ability. It should be noted that by supporting metal element components such as Cu and Mn in addition to Ti in combination, it is possible to prepare those for each purpose, and it is excellent even for adsorbed molecules such as ammonia and hydrogen sulfide, which have poor adsorption performance with activated carbon alone. Adsorption performance is developed.

[0021]

EXAMPLES Examples and comparative examples will be given below for illustrating the present invention more specifically, but the invention is not limited thereto. Examples 1 and 2 100 parts by weight of a novolac type phenol resin (manufactured by Gunei Chemical Industry Co., Ltd.) was dissolved in 400 parts by weight of ethanol to obtain an ethanol solution of the phenol resin. On the other hand, an ethanol solution of titanium tetrachloride (TiCl ₄ ) was prepared, and a predetermined amount thereof was mixed with each phenol ethanol solution and sufficiently stirred. Then, the ethanol is removed by rotary evaporation under reduced pressure to obtain a Ti-containing phenol resin. Next, each Ti-containing phenol resin obtained was centrifugally spun (diameter 14 μm) by a conventional method to obtain a phenol resin fiber. The above obtained fiber was added to formaldehyde 2
After soaking for 0 minute, the temperature was raised to 95 ° C. at a temperature rising rate of 0.5 ° C./minute and kept for 8 hours for curing. The obtained cured fiber was wrapped in a carbon cloth, heated in a horizontal tubular furnace to 800 ° C. at a temperature rising rate of 5 ° C./min in a nitrogen gas stream, held for 30 minutes and baked to be carbonized. Next, the nitrogen gas was changed to steam as a carrier gas, and the mixture was kept at 800 ° C. for 1.5 hours for activation treatment to obtain titanium oxide-supporting activated carbon fibers.

Comparative Example 1 An activated carbon fiber was obtained by the same operation and conditions as in Example 1 except that the titanium tetrachloride-ethanol solution was not used.

Comparative Example 2 100 parts by weight of the activated carbon fiber obtained in Comparative Example 1 was added to 20 w.
It was immersed for 5 minutes in 1500 parts by weight of t% anatase type titanium dioxide slurry. Then, it was filtered and dried to obtain a titanium dioxide-supporting activated carbon fiber.

<Evaluation of Physical Properties> Each of the activated carbon fibers obtained in Examples and Comparative Examples was subjected to chemical analysis and BET specific surface area was measured to evaluate physical properties. The results are shown in Table 1.

[0025]

[Table 1]

<Deodorization test> 10 cmφ without a lid
0.5 g of the activated carbon fibers prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was placed in the container and left in the center of an acrylic box of 30 liter capacity, and an ultraviolet lamp was fixed on the top of the box, and the lid was closed. To make a closed system. Next, using acetaldehyde and dimethyl disulfide as target gases, the gas is flown into the acrylic box until the concentration becomes 20 ppm, adsorbed for 1 hour, and then irradiated with ultraviolet rays for 1 hour.
Furthermore, the amount of the removed gas is added and the concentration is again 20 pp.
m, and the same cycle was repeated 3 times. The changes in the concentration of the target gas during each cycle are plotted and shown in FIGS. As can be seen from the results shown in these figures, the deodorizing photocatalytic activated carbon according to the present invention has a sufficient gas adsorption capacity and no deterioration was observed even in the continuous cycle.
On the other hand, the activated carbon fiber of Comparative Example 1 has a lower adsorptive removal capability with each cycle, and the titanium dioxide-impregnated activated carbon fiber of Comparative Example 2 has a poor gas adsorption and removal capability.

[0027]

INDUSTRIAL APPLICABILITY The deodorizing photocatalytic activated carbon according to the present invention has a high gas adsorption capacity and a wide adsorption spectrum as compared with the conventional method of supporting a photocatalyst on an adsorption carrier by impregnating, coating or kneading. It also has a photocatalytic function and excellent workability. Therefore, the steps of coating, impregnating, and kneading the photocatalyst on the deodorizing carrier are not necessary, and the specific surface area of the activated carbon itself can be effectively utilized. Therefore, it is possible to effectively apply to the field which cannot cope with the removal of thin pollutant gas or the removal of high level pollutant gas. Further, according to the production method of the present invention, such deodorizing photocatalytic activated carbon can be industrially advantageously obtained.

[Brief description of drawings]

FIG. 1 is a graph showing the results of a deodorization test of dimethyl disulfide in Example 1.

FIG. 2 is a graph showing the results of a deodorization test of dimethyl disulfide of Example 2.

FIG. 3 is a graph showing the results of a deodorization test of dimethyl disulfide of Comparative Example 1.

FIG. 4 is a graph showing the results of a deodorization test of dimethyl disulfide of Comparative Example 1.

FIG. 5 is a graph showing the results of the deodorizing test of acetaldehyde in Example 1.

FIG. 6 is a graph showing the results of an acetaldehyde deodorization test in Example 2.

7 is a graph showing the results of a deodorizing test for acetaldehyde in Comparative Example 1. FIG.

FIG. 8 is a graph showing the results of a deodorizing test for acetaldehyde in Comparative Example 2.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C01B 31/08 B01D 53/36 ZABJ

Claims (4)

[Claims] 1. A deodorizing photocatalytic activated carbon comprising a titanium oxide-supported activated carbon carbonized and activated in the presence of a Ti component as a main component. 2. The deodorizing photocatalytic activated carbon according to claim 1, wherein the titanium oxide-supporting activated carbon is fibrous. 3. The deodorizing photocatalytic activated carbon is Ti based on the total weight.
The deodorizing photocatalytic activated carbon according to claim 1 or 2, which is 0.1 to 30 wt%. 4. A method for producing a deodorizing photocatalytic activated carbon, which comprises uniformly mixing an activated carbon precursor organic substance and a Ti-containing solution, and then carbonizing by firing to activate the deodorizing photocatalytic activated carbon.