JP2789157B2 - Titanium oxide powder and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pigment, a catalyst, a catalyst carrier,
Titanium oxide powder useful as an adsorbent, etc. More specifically, a deodorant that adsorbs unpleasant odor gases such as ammonia, mercaptans, hydrogen sulfide, and aldehydes, and a harmful substance remover that decomposes harmful substances by photocatalytic reaction The present invention relates to a titanium oxide powder having a high specific surface area, which is suitable as a powder.

[0002]

2. Description of the Related Art Unpleasant odor gases which are likely to be produced in human living environment include ammonia, methyl mercaptan, hydrogen sulfide, trimethylamine, methyl sulfide, acetaldehyde and the like. Attempts have been made to remove these odorous gases and comfortably preserve the living environment. For example, a method of adsorbing odorous gases on activated carbon or impregnated carbon in which activated carbon is loaded with acid, alkali, etc. to remove odors Is adopted. However, since the activated carbon is black, the usable range is limited. For example, if activated carbon is added to sanitary products such as disposable diapers or sanitary napkins that come into direct contact with the human body, it will be necessary to treat the product so that it does not turn black to keep the product clean, In the case where activated carbon is blended in a decorative product or a cosmetic product, the product is hardly colored into a desired color, so that it can be used only for a black product. Activated carbon also has a problem that the deodorizing performance of ammonia is particularly low, and the deodorizing performance of odorous gas is deteriorated when moisture is first adsorbed. On the other hand, various adsorbents are commercially available, and silica gel, zeolite, activated alumina, activated clay, and the like are generally sold as white adsorbents that give a clean feeling and can color products in a desired color. Have been. However, these white adsorbents cannot be used in place of activated carbon because of their low deodorizing performance for the odorous gas. Therefore,
JP-B-3-33022 proposes, as a white deodorant, tightly bound particles composed of zinc oxide, titanium dioxide and water.

[0003]

SUMMARY OF THE INVENTION
In order to obtain a white deodorant described in No. 22, a mixed aqueous solution of a water-soluble titanium compound and a water-soluble zinc compound and an alkaline aqueous solution are simultaneously combined so that the pH of a combined solution of the two is in the range of 6 to 11. And neutralized, titanium dioxide,
It is necessary to obtain tightly-coupled particles having a uniform composition composed of zinc oxide and water. In this method, it is necessary to precisely control the concentration of the raw material such as the titanium compound and the coalescing speed of the two, and the operation becomes complicated. In addition, p of the combined liquid
When H fluctuates outside the above range, the obtained white deodorant is not excellent in characteristics.
No. 22. In addition, since the precipitate deposited by neutralization is in a gel state, there are problems to be improved, such as difficulty in filtration, and solidification of the particles of the precipitate by drying to make pulverization difficult.

[0004]

Means for Solving the Problems The inventors of the present invention have been conducting various studies on increasing the value of titanium oxide as a functional material for a long time.
We focused on applying titanium oxide as a white deodorant, and proceeded with research. As a result, titanium oxide becomes ammonia,
Although it was excellent in the deodorizing performance of basic gases such as trimethylamine, it was found that the deodorizing performance of methyl mercaptan, hydrogen sulfide and the like was low. After further intensive studies, a powder obtained by supporting zinc oxide obtained by neutralizing a zinc compound with a water-soluble alkali compound of an alkali metal or an alkaline earth metal on titanium oxide base particles. The body has (1) excellent odor gas deodorizing performance, and (2) filtration, drying and drying of the product without requiring complicated operations.
It has been found that pulverization and the like can be easily performed, and that (3) a product of stable quality is easily obtained and is practically suitable, and the present invention has been completed. Further, when a titanium oxide powder carrying a zinc oxide further carries a silicon oxide, the amount of the zinc oxide dissolved is small, and
The inventor has found out that the odorous gas has excellent deodorizing performance, and has completed the present invention. Furthermore, when titanium oxide powder carrying zinc oxide or titanium oxide powder further carrying silicon oxide is irradiated with light containing ultraviolet rays in the presence of oxygen, it emits malodorous substances and irritants due to a photocatalytic reaction. Finding that it can decompose and remove harmful substances such as substances that adversely affect the human body and the living environment, and in particular that it can decompose and remove the above-mentioned odorous gas,
The present invention has been completed. That is, the present invention particularly relates to a white powder excellent in deodorizing performance of a malodorous gas and a method for easily and easily producing the same.

The present invention relates to a titanium oxide powder having titanium oxide base particles carrying a specific amount of zinc oxide, and a titanium oxide powder having a specific amount of zinc and silicon oxide supported thereon. The titanium oxide referred to in the present invention includes so-called titanium oxide as well as hydrous titanium oxide. The oxide of zinc refers to zinc oxide, zinc hydroxide, and the like, and the oxide of silicon refers to silicon oxide, silicic acid, silicate, and the like. The term “support” as used in the present invention refers to a state in which zinc oxide and silicon oxide are distributed or present in the form of islands on the surface of single particles of titanium oxide base particles or aggregated particles thereof. A state in which the entire surface of the particles is covered with a continuous coating layer or a state in which the particles are taken in the gaps between the titanium oxide base particles. It is sufficient if they are in a state of contact with each other chemically or chemically. The amount of zinc oxide supported on the titanium oxide substrate particles can be arbitrarily changed depending on the composition of the target malodorous gas, but generally, the molar ratio of Ti: Zn = 9 to Zn of the substrate is as follows: Ti: Zn = 9.
9: 0.1 to 5: 5, particularly preferably 9.5: 0.5 to 7: 3. If the supported amount is less than the above range, methyl mercaptan, the deodorizing performance of hydrogen sulfide and the like are undesirably reduced, and if it is more than the above range, the amount of free zinc oxide is increased, and the deodorizing performance of ammonia and trimethylamine is reduced. Or it is not desirable.

Further, the present invention relates to a titanium oxide powder in which titanium oxide base particles carry zinc and silicon oxides. The amount of silicon oxide carried is arbitrary depending on the composition of the target odorous gas. Can be changed to In general, a zinc oxide is used in a molar ratio of T
i: Zn = 9.9: 0.1 to 5: 5, especially 9.5: 0.
The amount of 5: 7: 3, and the molar ratio of Zn: Si = 9:
It is preferred to carry an amount of 1 to 0.1: 9.9, especially 9: 1 to 4: 6. When the amount of silicon oxide carried is less than the above range, zinc oxide is easily dissolved in an aqueous solution, particularly in an acidic aqueous solution, and when used as a deodorant such as a disposable diaper, the deodorizing performance is reduced, and the eluted zinc ions cause human body damage. It is not preferable because it may adversely affect the operation. On the other hand, when the amount of the silicon oxide carried is larger than the above range, the dissolution of the zinc oxide is reduced, but the deodorizing performance for a specific malodorous gas is undesirably reduced.

When the titanium oxide powder of the present invention is used particularly as a deodorant, it is desirable that the specific surface area be 100 m ² / g or more in order to obtain a deodorant having good deodorizing speed and deodorizing performance. If the specific surface area is less than 100 m ² / g, the deodorizing performance is substantially insufficient, and it is difficult to obtain a suitable deodorizing agent.

[0008] In the method of the present invention, the titanium oxide powder in which zinc oxide is supported on the titanium oxide base particles is obtained by adding a zinc compound and an alkali to a dispersion of the titanium oxide base particles. Neutralizing the zinc compound in a dispersion of particles, then separating the resulting product,
Obtained by drying. In the present invention, as the titanium oxide base particles, titanium oxide that can be obtained by various known methods can be used. As a method for obtaining titanium oxide, for example, titanyl sulfate, titanium chloride,
A method of heat-hydrolyzing a titanium compound such as an organic titanium compound, if necessary, in the presence of seeds for nucleation, adding an alkali to a titanium compound such as titanyl sulfate, titanium chloride, or an organic titanium compound to neutralize the compound. A method of vapor-phase oxidation of titanium chloride, an organic titanium compound, or the like, and a method of baking the titanium oxide obtained by the above method at a temperature of about 600 ° C. or less, and the titanium oxide obtained by these methods. Can be used as titanium oxide base particles. In the present invention, the above-described titanium oxide base particles are dispersed in a solvent such as water, and classified if necessary to obtain a dispersion. As the zinc compound to be added to the dispersion, for example, various compounds such as zinc chloride, zinc sulfate, and zinc nitrate can be used. The alkali is preferably a water-soluble alkali compound of an alkali metal or an alkaline earth metal, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium silicate, barium hydroxide and the like. If ammonia or ammonium salt is used as the alkali, a complex ion with a zinc compound is formed, which tends to dissolve zinc oxide, which is not desirable. As a method of neutralizing a zinc compound in a dispersion of titanium oxide base particles,
For example, a method of simultaneously adding and neutralizing a zinc compound and an alkali to a dispersion of titanium oxide base particles, a method of adding a zinc compound to a dispersion of titanium oxide base particles, and then neutralizing by adding an alkali; After alkali is added to the dispersion of the titanium oxide base particles, a zinc compound is added to neutralize the dispersion, and any method may be used. The zinc compound is generally neutralized and precipitated in a pH range of about 6 to 11. The conditions such as the concentration of the titanium oxide base particles in the dispersion, the amount of the zinc compound and alkali added, and the respective concentrations and addition rates when these are used as an aqueous solution, and the temperature during the neutralization reaction are not particularly limited. And can be set appropriately. Prior to the neutralization reaction,
In order to improve the dispersion state of the titanium oxide substrate particles in the dispersion, orthophosphoric acid, pyrophosphoric acid, hexametaphosphoric acid or an alkali salt thereof, sodium orthosilicate, sodium metasilicate and the like dispersing agent of titanium oxide powder It can also be added to the dispersion within a range that does not adversely affect the deodorizing performance. The product obtained in this way is separated off, optionally washed and dried. Separation can be performed by a conventional method such as filtration or a gradient method. Drying can be performed at a temperature of 100 to 600C, but a temperature of 100 to 200C is suitable. The dried powder can be pulverized or pulverized into powder or molded into granules depending on the use scene. Since the specific surface area of the obtained titanium oxide powder tends to decrease as the amount of supported zinc oxide increases, in order to obtain a titanium oxide powder having a specific surface area of more than 100 m ² / g, the specific surface area is 100 m ² / g. It is desirable to use titanium oxide substrate particles greater than ² / g.

Next, in the method of the present invention, a titanium oxide powder in which titanium oxide substrate particles carry zinc and silicon oxides can be produced according to the above-described method of carrying zinc oxide. . That is, by adding a zinc compound, a silicon compound and a neutralizing agent to the dispersion of titanium oxide base particles, the zinc compound and the silicon compound are neutralized in the dispersion of titanium oxide base particles, and then The product obtained is separated off and dried. Examples of the silicon compound include water glass, sodium orthosilicate,
Various materials such as sodium metasilicate and silicon chloride can be used. As the neutralizing agent, various acids such as hydrochloric acid, sulfuric acid and nitric acid can be used in addition to the above-mentioned alkalis. The neutralization of the silicon compound can be carried out in accordance with the above-described method of neutralizing the zinc compound, and generally, about 6 to
Neutralize and precipitate in a pH range of 11. The zinc compound and the silicon compound can be neutralized simultaneously or separately. When neutralized at the same time, zinc oxide and silicon oxide can be coprecipitated and supported, and when neutralized separately, for example, zinc oxide is supported and then silicon oxide is supported. You can also. When the titanium oxide powder of the present invention is used as a deodorant, first, a titanium compound is neutralized with an alkali or hydrolyzed to form titanium oxide base particles in a liquid phase. A method in which a zinc compound, a silicon compound and a neutralizing agent are simultaneously added to and supported on a liquid in which the base particles are dispersed is particularly preferable. The concentration of the titanium oxide base particles in the dispersion,
The amount of the silicon compound, the zinc compound and the alkali added, and the concentration and rate of addition of each of these when used as an aqueous solution, and the conditions such as the temperature during the neutralization reaction, can be appropriately set without any particular limitation. The product thus obtained is separated, washed if necessary, and dried in the same manner as in the above-mentioned method of supporting a zinc oxide. Separation can be performed by a conventional method such as filtration or a gradient method. Drying can be performed at a temperature of 100 to 600C, but a temperature of 100 to 200C is suitable. The dried powder can be pulverized or pulverized into powder or molded into granules depending on the use scene.

In the present invention, a titanium oxide powder having zinc oxide supported on titanium oxide base particles or a titanium oxide powder having zinc and silicon oxide supported on titanium oxide base particles is directly used as a deodorant or harmful substance. Although it can be used as a substance remover, it can also be used as a mixture with substances commonly used in this field, such as aluminum oxide and zeolite. By bringing a malodorous gas into contact with the deodorant containing the titanium oxide powder of the present invention, various malodorous gases can be efficiently deodorized. In addition, the harmful substance removing agent containing the titanium oxide powder of the present invention, under irradiation of light containing ultraviolet rays in the presence of oxygen, by contacting the harmful substance, efficiently decompose various harmful substances. Can be removed. As the ultraviolet light used in the present invention, near ultraviolet light having a wavelength of 300 to 400 nm is preferable. The harmful substance remover containing the titanium oxide powder of the present invention can be applied to various harmful substances such as malodorous substances, irritating substances, substances which have a bad influence on human body and living environment. Decomposition and sterilization of air pollutants such as nitrogen oxides and sulfur oxides, water pollutants such as oil, and organic compounds such as polychlorinated biphenyl and dioxin.

[0011]

【Example】

Example 1 A 10 mol of 2 mol / l titanyl sulfate solution was heated and hydrolyzed in the presence of nucleated seeds to obtain a precipitate. Subsequently, the precipitate was filtered, washed, and dried to obtain titanium oxide. The specific surface area (according to the BET method; the same applies hereinafter) of this titanium oxide was 290 m ² / g. next,
80 g of the titanium oxide base particles were dispersed in 1 liter of pure water, heated to a temperature of 40 ° C., and 2 g of the dispersion was added.
An aqueous solution of N sodium hydroxide was added dropwise to adjust the pH of the dispersion to 8. Then, 1 mol is added to this dispersion under stirring.
/ Ml of zinc chloride aqueous solution and 2N aqueous sodium hydroxide solution were simultaneously added dropwise over 10 minutes while maintaining the pH of the dispersion at 8 to obtain a product. Subsequently, this product was filtered, washed, dried at a temperature of 120 ° C., and then crushed to obtain a titanium oxide powder (Sample A) of the present invention.

Example 2 A titanium oxide powder (sample B) of the present invention was obtained in the same manner as in Example 1, except that 50 ml of an aqueous zinc chloride solution was added dropwise.

Example 3 The procedure of Example 1 was repeated, except that 430 ml of an aqueous zinc chloride solution was added dropwise, to obtain a titanium oxide powder (sample C) of the present invention.

Example 4 Titanium oxide base particles 8 produced according to the method of Example 1
0 g was dispersed in 1 liter of pure water. After adding 15 g of zinc chloride powder to the dispersion, the mixture was heated to a temperature of 40 ° C. Then, a 2N aqueous solution of sodium hydroxide was added dropwise to the dispersion over 10 minutes with stirring to adjust the pH of the dispersion to 8 to obtain a product. Subsequently, the product was filtered, washed, dried at a temperature of 120 ° C., and then crushed to obtain a titanium oxide powder (Sample D) of the present invention.

Example 5 Titanium oxide base particles 8 produced according to the method of Example 1
0 g was dispersed in 1 liter of pure water. After adding 8.9 g of sodium hydroxide to this dispersion, the mixture was heated to a temperature of 40 ° C. Then, under stirring, 110 ml of a 1 mol / l aqueous zinc chloride solution was added dropwise to this dispersion over 10 minutes to finally adjust the pH of the dispersion to 8 to obtain a product. Subsequently, the product was filtered, washed, dried at a temperature of 120 ° C., and then crushed to obtain a titanium oxide powder (Sample E) of the present invention.

Example 6 One liter of a 1 mol / l titanium tetrachloride aqueous solution was heated and hydrolyzed in the presence of nucleated seeds to obtain a precipitate of titanium oxide. (The titanium oxide precipitate was filtered, washed, and dried, and the specific surface area was 160 m ² / g.) The dispersion of the titanium oxide base particles thus obtained was heated to 40 ° C. After the adjustment, a 2N aqueous solution of sodium hydroxide was added dropwise to the dispersion to adjust the pH of the dispersion to 8. Then, under stirring, 110 ml of a 1 mol / l aqueous solution of zinc chloride and a 2N aqueous solution of sodium hydroxide were simultaneously added dropwise to the dispersion over 10 minutes while maintaining the pH of the dispersion at 8 to obtain a product. The product was filtered, washed, dried at a temperature of 120 ° C., and then crushed to obtain a titanium oxide powder (Sample F) of the present invention.

COMPARATIVE EXAMPLE 1 One liter of a 1 mol / l aqueous zinc chloride solution was heated to a temperature of 40 ° C., and a 2N aqueous sodium hydroxide solution was added dropwise with stirring over 100 minutes to adjust the pH of the aqueous solution to 8 to form a solution. I got something. The product is filtered, washed and
And then crushed to obtain a zinc hydroxide powder (Sample G).

Comparative Example 2 Titanium oxide obtained by the method of Example 1 and not treated with zinc chloride was used as Sample H.

In each case of Examples 1 to 6, filtration and washing of the precipitate were relatively quick, and the dried titanium oxide powder was easily loosened and easily pulverized. .

Samples obtained in Examples and Comparative Examples (A to
Table 1 shows the specific surface area of H) and the adsorption rate of the offensive odor gas. The odor gas adsorption rate of the sample was measured by the following method. First, trimethylamine, methyl mercaptan, and hydrogen sulfide were each diluted with nitrogen gas to about 1000 ppm. Next, 1 liter of the above-mentioned diluent gas was introduced into a polyester bag containing 0.1 g of the sample, sealed, and allowed to stand for 5 hours. Thereafter, the concentration of the malodorous gas remaining in the bag was measured with a gas chromatograph or a gas detector tube, and the adsorption rate was calculated from the concentration of the introduced diluent gas.

[0021]

[Table 1]

Example 7 150 ml of a 1 mol / l aqueous solution of titanium tetrachloride was added at 40 ° C.
Then, a 4N aqueous solution of sodium hydroxide was added dropwise over 10 minutes with stirring, and the pH of the aqueous solution was adjusted to 3 to obtain a precipitate of titanium oxide. The dispersion of titanium oxide base particles thus obtained was stirred for 3 m.
50 ml of an ol / l zinc chloride aqueous solution, 36.8 g of sodium orthosilicate and a 4N aqueous sodium hydroxide solution were simultaneously added dropwise over 10 minutes while maintaining the pH of the dispersion at 8 to obtain a product. The product is filtered, washed and
It was dried at a temperature of 20 ° C. and then crushed to obtain a titanium oxide powder of the present invention (Sample I).

Example 8 In Example 7, 225 ml of an aqueous solution of titanium tetrachloride was added.
The same treatment as in Example 7 was carried out except that the aqueous zinc chloride solution was 75 ml and the sodium orthosilicate was 9.2 g,
A titanium oxide powder (sample J) of the present invention was obtained.

Example 9 The procedure of Example 7 was repeated, except that sodium orthosilicate was not added, to obtain a titanium oxide powder (sample K) of the present invention.

Table 2 shows the results of measuring the specific surface area and the adsorption rate of the odorous gas of the samples (I to K) obtained in the examples in the same manner as described above. These samples are excellent in the adsorption rate of the malodorous gas, and it is understood that these samples are preferable as a white deodorant. Next, 1 g of each of these samples was dispersed in 100 ml of a 0.01 N hydrochloric acid aqueous solution and 100 ml of a 0.01 N sodium hydroxide aqueous solution, respectively, and stirred at a temperature of 40 ° C. for 3 hours. The amount of zinc ions present in the solution was measured by emission analysis. Table 3 shows the results. Samples I and J have similar solubility to alkaline aqueous solution as compared to sample K, but are hardly soluble in acidic aqueous solution.

[0026]

[Table 2]

[0027]

[Table 3]

Comparative Example 3 100 ml of a 1 mol / l aqueous zinc chloride solution and 1 mol / l
of a titanium tetrachloride aqueous solution (900 ml).
The mixture was heated to a temperature of 0 ° C., and then a 4N aqueous sodium hydroxide solution was added dropwise at a rate of 10 ml / min with stirring to adjust the pH of the mixture to 8 to obtain a product. The product is filtered,
The powder was washed, dried at a temperature of 120 ° C., and then crushed to obtain a powder (sample L) of titanium oxide and zinc hydroxide.

The samples obtained in the examples and comparative examples (A,
L), the photocatalytic decomposition of the odorous gas was investigated. First, 0.1 g of each sample was dispersed in 5 ml of ethanol, and then these dispersions were poured into a petri dish having a diameter of 8.6 cm, and dried at a temperature of 70 ° C., thereby uniformly disposing the sample on the bottom of the petri dish. These petri dishes were placed in a plastic sealed container (with an internal volume of about 8 liters) equipped with a 4 W black light, and acetaldehyde and methyl mercaptan were respectively injected. Next, after standing in the dark for 2 hours, the black light was turned on to perform a photocatalytic reaction, and the change in the concentration of the offensive odor gas in the sealed container was measured by gas chromatography. The light irradiation intensity is 310 to 400 n
The light having a wavelength of m was about 1 mW / cm ² . FIG. 1 shows the photocatalytic decomposition of acetaldehyde, and FIG. 2 shows the photocatalytic decomposition of methyl mercaptan. Table 4 shows the results of the photocatalytic reaction speed obtained from the inclination of the straight line when the black light is turned on in FIGS.

[0030]

[Table 4]

[0031]

The titanium oxide powder of the present invention in which zinc oxide is supported on titanium oxide base particles is useful for pigments, catalysts, catalyst carriers, adsorbents and the like. In particular, it is excellent in deodorizing performance of malodorous gases such as ammonia, methyl mercaptan, hydrogen sulfide, trimethylamine, methyl sulfide, and acetaldehyde, and is suitable as a white deodorant for sanitary articles such as disposable diapers and sanitary napkins that directly touch the human body. Further, the titanium oxide powder of the present invention in which zinc and silicon oxides are supported on titanium oxide base particles has a small amount of dissolved zinc oxide, and is excellent in deodorizing performance of malodorous gas, Particularly, it is suitable as a white deodorant for sanitary articles such as disposable diapers and sanitary napkins that directly touch the human body. Furthermore, the titanium oxide powder of the present invention can remove harmful substances quickly and efficiently by a photocatalytic reaction, and is therefore extremely useful not only for industrial use but also as a general household deodorant. In addition, the harmful substance remover containing the titanium oxide powder of the present invention is highly safe and has a wide range of applicable harmful substances. It is. The method of the present invention is a simple method for preparing a stable quality titanium oxide powder,
And, it can be easily manufactured, and the filtration and washing of the product during the manufacturing process are relatively quick, and the powder after drying is easy to be loosened and easy to pulverize. is there.

[Brief description of the drawings]

FIG. 1 is a graph showing experimental results of photocatalytic decomposition of acetaldehyde. FIG. 2 is a graph showing experimental results of photocatalytic decomposition of methyl mercaptan.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-91135 (JP, A) JP-A-2-196029 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C01G 23/00

Claims (12)

(57) [Claims] A zinc oxide obtained by neutralizing a zinc compound with a water-soluble alkali compound of an alkali metal or an alkaline earth metal is coated on a titanium oxide substrate particle.
With respect to Ti in a molar ratio of Ti: Zn = 9.9: 0.1
~ 5: Titanium oxide powder carrying an amount of 5 2. Titanium oxide base particles are coated with zinc and silicon oxides in a molar ratio of Ti: Zn = 9.9: 0.1 to 5: 5 as Zn with respect to Ti of the base. Zn: Si = 9 in molar ratio as Si with respect to Zn of zinc oxide:
Titanium oxide powder supporting an amount of 1 to 0.1: 9.9. 3. The titanium oxide powder according to claim 1, wherein the specific surface area is 100 m ² / g or more. 4. The method according to claim 1, wherein the molar ratio of Ti: Zn is 9.5: 0.5 to
The titanium oxide powder according to claim 1 or 2, wherein the ratio is 7: 3. 5. A dispersion of titanium oxide-based particles, wherein a water-soluble alkali compound of an alkali metal or an alkaline earth metal and a zinc compound are added to the dispersion of titanium-oxide-based particles. A method for producing titanium oxide powder in which zinc oxide is supported on titanium oxide base particles, and the obtained product is separated and dried. 6. A method for neutralizing said zinc compound and said silicon compound in said dispersion of titanium oxide base particles by adding a zinc compound, a silicon compound and a neutralizing agent to said dispersion of titanium oxide base particles. Then, the obtained product is separated and dried to produce a titanium oxide powder in which zinc oxide and silicon oxide are supported on titanium oxide base particles. 7. A deodorant comprising the titanium oxide powder according to claim 1. 8. A harmful substance removing agent which comprises the titanium oxide powder according to claim 1 and decomposes harmful substances by a photocatalytic reaction. 9. A deodorizing agent comprising the titanium oxide powder according to claim 1, which decomposes odorous gas by a photocatalytic reaction. 10. A deodorant comprising the titanium oxide powder according to claim 2. 11. A harmful substance removing agent which comprises the titanium oxide powder according to claim 2 and decomposes harmful substances by a photocatalytic reaction. 12. A deodorant comprising the titanium oxide powder according to claim 2, which decomposes odorous gas by a photocatalytic reaction.