JP2004043282A - Method of manufacturing titanium oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing titanium oxide showing high photocatalytic activity. <P>SOLUTION: The method of manufacturing titanium oxide is performed by mixing a titanium compound and a 2nd ingredient composed of an element or the compound selected from group IIa elements, group IIIa elements, group Va elements, group VIa elements, group VIIa elements, group VIII elements, group Ib elements, group IIb elements, group IIIb elements, lanthanoid, silicon, germanium, tin, lead, antimony, bismuth, zirconium and hafnium with a solvent, reacting a base with the mixture under a condition in which the solubility of the hydroxide of the element constituting the 2nd ingredient is made ≤10<SP>-4</SP>g/L and firing the resultant solid. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing titanium oxide, and more particularly, to a method for producing titanium oxide suitable for photocatalytic applications.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, it has been studied to remove malodorous substances in the atmosphere by using a photocatalytic action and to impart a self-cleaning action to window glass and road walls (see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-9-57912
[0004]
In recent years, photocatalysts made of titanium oxide exhibiting photocatalytic activity against visible light irradiation have been developed, and since a light source capable of irradiating ultraviolet light is not required, it has become widely applicable. For example, application development for indoor use such as in a tunnel, which was previously difficult to apply, is being promoted.
[0005]
On the other hand, in such indoor use, a light beam from an illuminating device such as a fluorescent lamp or a sodium lamp is directly irradiated on the photocatalyst, and thus a sufficient amount of light for obtaining the photocatalytic action may not always be obtained. Therefore, further improvement in activity of titanium oxide as a raw material is demanded so that high photocatalytic activity can be obtained even with a small amount of light.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a method capable of producing titanium oxide having higher photocatalytic activity than conventional ones.
[0007]
[Means for Solving the Problems]
The present inventors have conducted various studies on a method for producing titanium oxide in order to improve the photocatalytic activity of titanium oxide, and as a result, have completed the present invention.
[0008]
That is, the present invention relates to a titanium compound, a group IIa element, a group IIIa element, a group Va element, a group VIa element, a group VIIa element, a group VIII element, a group Ib element, a group IIb element, a group IIIb element, a lanthanoid, silicon, and germanium. , Tin, lead, antimony, bismuth, zirconium and hafnium, a second component comprising the compound or a compound thereof, and a solvent, and mixing the mixture with a base and a hydroxide of the element constituting the second component. Has a solubility of 10 ^-4 It is intended to provide a method for producing titanium oxide, wherein the reaction is carried out under a condition of g / L or less, and the obtained solid is calcined.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail. In the production method of the present invention, first, a titanium compound, a component other than the titanium compound, and a solvent are mixed. The titanium compound used here may be any compound that generates titanium hydroxide by reacting with a base in the presence of water. For example, titanium trichloride [TiCl ₃ ], Titanium tetrachloride [TiCl ₄ ], Titanium sulfate [Ti (SO ₄ ) ₂ ・ MH ₂ O, 0 ≦ m ≦ 20], titanium oxychloride [TiOCl ₂ ], Titanium oxysulfate [TiOSO ₄ ・ NH ₂ O, 0 ≦ n ≦ 20], among which titanium oxysulfate is preferably used.
[0010]
As components other than the titanium compound, for example, beryllium, magnesium, calcium, strontium, group IIa element such as barium, scandium, group IIIa element such as yttrium, zirconium, group IVa element such as hafnium, vanadium, niobium, Group Va element such as tantalum, chromium, molybdenum, group VIa element such as tungsten, manganese, technetium, group VIIa element such as rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum Group VIII elements such as copper, silver, gold, Group Ib elements such as zinc, cadmium, boron, aluminum, gallium, indium, group IIIb elements such as thallium, silicon, germanium, tin, Like lead Group IVb elements such as IVb elements, antimony and bismuth, lanthanides such as lanthanum, cerium, praseodymium, neodymium, samarium, europium and gadolinium, preferably zinc, zirconium, gallium, indium, iron and niobium And more preferably zinc and niobium. The components other than the titanium compound may be used alone or in combination of two or more. Components other than the titanium compound are usually mixed with the titanium compound in the form of a compound, but may be mixed with the titanium compound alone as long as it can be uniformly dispersed in the solvent. Examples of the compound of the element other than titanium include various inorganic compounds and organic compounds of the element. Examples of the inorganic compound include sulfates, nitrates, and chlorides of these elements. Elemental oxalate, hydrogen oxalate, acetate and the like. It is preferable that the components other than the titanium compound are soluble in the solvent used or can be present as colloidal particles in the solvent. The amount of the component other than the titanium compound is 0.00001 mol times or more, preferably 0.0001 mol times or more, further 0.001 mol times or more, and 0% or less, based on the element constituting the titanium compound. It is preferably at most 0.1 mol times, more preferably at most 0.05 mol times.
[0011]
The solvent only needs to dissolve the titanium compound, and usually, water and aqueous hydrogen peroxide are used.
[0012]
In the present invention, the base is then reacted with a mixture of the titanium compound, a component other than the titanium compound, and the solvent. Examples of the base used herein include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonia, hydrazine, hydroxylamine, monoethanolamine, acyclic amine compounds, and cyclic aliphatic amine compounds. . Among them, application of ammonia is preferred. When the base is used after mixing with a solvent in which the base is soluble in the reaction with the mixture, the concentration of the base is usually 0.05% by weight or more and 50% by weight or less.
[0013]
The reaction between the above mixture and the base is such that the solubility of the hydroxide of the constituent element of the component other than the titanium compound is 10%. ^-4 g / L or less, preferably 10 ^-6 g / L or less. When two or more components are mixed with the titanium compound, the solubility of the hydroxides of the elements constituting these components is 10% or less. ^-4 It is preferable to carry out the reaction under the condition of g / L or less. By performing the reaction under the conditions lower than the solubility, it is not clear why titanium oxide having high photocatalytic activity is obtained, but when a base is reacted with a mixture of a titanium compound and a component other than the titanium compound and a solvent, It is conceivable that the hydroxide of the element constituting this component rarely dissolves in the solvent and remains, and that it is influenced by the uniform incorporation into the generated titanium hydroxide.
[0014]
The reaction is performed when the solubility of the hydroxide is 10 ^-4 As long as the condition is not more than g / L, the reaction can be carried out by appropriately selecting a solvent and adjusting pH, temperature and the like. In the case where water is used as a solvent and the solubility is adjusted by pH, the solubility of the hydroxide is 10% for each element. ^-4 The pH below g / L is shown below. As shown in FIGS. 1 to 5, the pH at this time can be obtained from a correlation diagram of pH-metal hydroxide solubility, and zinc hydroxide [Zn (OH) ₂ ], The pH is 7.4 to 12.5 as shown in FIG. As an element other than zinc, for example, gallium hydroxide [Ga (OH) ₃ ], The pH is 3.5 to 10.5 as shown in FIG. 2 and indium hydroxide [In (OH) ₃ ], The pH is 4.2 to 11.8 as shown in FIG. 3, and the zirconium hydroxide [Zr (OH) ₂ ・ 2H ₂ O], as shown in FIG. 4, the pH is 2.5 or more, and iron hydroxide [Fe (OH) ₃ ], The pH is 3.2 or more as shown in FIG. In addition, the solubility of the hydroxide is 10 for each element. ^-6 The same applies to a pH value of not more than g / L. Zinc hydroxide [Zn (OH) ₂ ], PH 8.4 to 10.6 (FIG. 1), gallium hydroxide [Ga (OH) ₃ ], The pH is 5.7 to 9.2 (FIG. 2) and the indium hydroxide [In (OH) ₃ ], The pH is 5.2 to 9.8 (FIG. 3) and the zirconium hydroxide [Zr (OH) ₂ ・ 2H ₂ O], the pH is 3.5 to 12.5 (FIG. 4) and the iron hydroxide [Fe (OH) ₃ ], The pH is 4.2 or more (FIG. 5).
[0015]
In addition, niobium hydroxide [Nb (OH) ₅ ] At a wide range of pH (approximately 1 to 13). ^-4 For those having a g / L or less, the reaction can be carried out at any pH within this range. In this case, the pH of the reaction is preferably determined in consideration of the mixture of the titanium compound and the components other than the titanium compound and the solvent, and the ease of handling of the reaction product of the base with the mixture. The preferred pH when the element constituting the component is niobium is 3-5.
[0016]
The reaction is preferably performed at 90 ° C. or lower. When the reaction temperature is higher than 90 ° C., the photocatalytic activity of the obtained titanium oxide may decrease. The lower the reaction temperature is, the more preferable it is to obtain titanium oxide exhibiting higher photocatalytic activity. For example, the reaction temperature is preferably 60 ° C or lower, more preferably 40 ° C or lower. On the other hand, in order to maintain a low reaction temperature, the cooling cost becomes high, for example, a large amount of refrigerant is required. The reaction rate at this time is usually 90% or more. The reaction rate can be adjusted by selecting the type of solvent or changing the temperature, time, stirring conditions, and the like. This reaction rate indicates the rate at which the titanium compound was hydrolyzed by the reaction with the base and changed to titanium hydroxide.
[0017]
In the reaction, specifically, after water is put in a container with a cooling jacket, a mixture of the titanium compound and a component other than the titanium compound and water is added to this container while stirring, while maintaining the liquid temperature within a predetermined range. And a method of supplying a base so as to have a predetermined pH, or a mixture of a titanium compound and a component other than the titanium compound and water and a base in a tube with a cooling jacket capable of controlling the reaction temperature, at a predetermined pH. It can be carried out by a continuous supply method or the like while adjusting the respective amounts so as to be as follows.
[0018]
The product obtained by the reaction may be aged. Aging can be performed by a method of keeping the slurry containing the product at a constant temperature in the presence of a base. Aging may be performed, for example, by subjecting a solution containing a salt (eg, ammonium sulfate) produced by the reaction to solid-liquid separation from the mixture after the reaction, adding a base to the obtained solid, and maintaining the solid at a constant temperature. it can. By performing this aging, the titanium oxide obtained by sintering the product exhibits excellent activity against irradiation with visible light. Examples of the base used for aging include ammonia water and the like, and the concentration is usually 0.05% by weight or more and 50% by weight or less. The aging temperature is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, and 110 ° C. or lower, further preferably 80 ° C. or lower. The aging time varies depending on the base concentration and the aging temperature and is not unique, but is usually 0.01 hours or more, preferably 0.5 hours or more, and is 60 hours or less, preferably 24 hours or less. The base used for ripening and the base used for the above-mentioned reaction may be of the same kind and the same concentration, different concentrations of the same kind, or different types.
[0019]
The total amount of base used in the above-mentioned reaction and optional aging may exceed the stoichiometric amount of base required to convert the titanium compound to titanium hydroxide in the presence of water. Preferably, for example, it is preferably at least 1.1 times the stoichiometric amount. Since the photocatalytic activity of the finally obtained titanium oxide tends to increase as the amount of the base used increases, it is more preferably 1.3 times or more. On the other hand, if the amount of the base is too large, the effect of improving the photocatalytic activity commensurate with the amount cannot be obtained. Therefore, the amount is suitably 20 times or less, more preferably 10 times or less.
[0020]
The slurry after the reaction or the slurry containing the product after aging is usually subjected to an operation of separating a solid. Separation can be performed by pressure filtration, vacuum filtration, centrifugation, decantation, or the like, or can be performed by a method in which the slurry is used to evaporate the liquid using a spray dryer or the like. The separated solid is washed and dried if necessary, and then fired. The firing is performed at a temperature of 300 ° C. or higher, preferably 350 ° C. or higher, 600 ° C. or lower, preferably 500 ° C. or lower, more preferably 450 ° C. or lower. If the firing temperature is too high, it becomes difficult to obtain titanium oxide having sufficient photocatalytic activity. The firing can be performed, for example, in a standing furnace, a tunnel furnace, a rotary furnace, or the like. Here, the method of calcining the solid after separating the solid in the slurry has been described.However, the product or the slurry containing the matured product is dried using a flash dryer such as a flash jet drier to produce the product. The product may be calcined without previously performing a solid-liquid separation operation on the slurry containing.
[0021]
The titanium oxide obtained by the above-described production method of the present invention usually has a crystal structure of an anatase type and exhibits high photocatalytic activity against irradiation with visible light. This titanium oxide also shows photocatalytic activity against ultraviolet light irradiation.
[0022]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.
Example 1
(Preparation of titanium oxide)
102 g of titanium oxysulfate hydrate (manufactured by Soegawa Rikagaku) was dissolved in 408 g of water to prepare an aqueous solution of titanium oxysulfate having a pH of about 1. To this aqueous solution of titanium oxysulfate, 1.21 g of zinc sulfate heptahydrate (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added and dissolved to obtain a mixed aqueous solution. The amount of zinc in the mixed aqueous solution was 0.01 mol times with respect to titanium.
[0023]
A pH electrode, a pH controller connected to the pH electrode and having a mechanism for supplying 25% by weight of aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) to constantly adjust the pH, and using a refrigerant were used. After 300 g of water was put into a 1 L flask having a cooling mechanism, the flask was cooled. The pH set value of the pH controller was set to 9, and the pH of the water was adjusted to the set value. While stirring at 400 rpm, 511.21 g of the mixed aqueous solution obtained above was added at 5 ml / min into the flask, and reacted with ammonia water supplied into the flask by a pH controller. During this time, the amount of 25% by weight aqueous ammonia supplied into the flask was 82.54 g.
[0024]
The pH of the liquid in the flask was pH 9.0 to 9.8 for 12 minutes after the addition of the mixed aqueous solution was started, and pH 8.9 to 9.2 from 12 minutes after the start of the addition to the end of the addition. . During that time, the liquid temperature in the flask was 1.1 to 6.2 ° C. The total amount of supplied ammonia water was 1.4 times the stoichiometric amount of the base required to convert titanium oxysulfate to titanium hydroxide.
[0025]
The obtained slurry was filtered, washed and dried, and the dried product was fired in air at 400 ° C. for 1 hour to obtain particulate titanium oxide. The titanium oxide was analyzed by an X-ray diffractometer (trade name “RAD-IIA”, manufactured by Rigaku Corporation). As a result, the crystal structure was anatase type.
[0026]
(Activity evaluation of titanium oxide)
A glass petri dish having a diameter of 5 cm was placed in a sealed glass reaction vessel having a diameter of 8 cm, a height of 10 cm, and a capacity of about 0.5 L, and 0.3 g of the particulate anatase-type titanium oxide obtained above was placed on the petri dish. I put it. The inside of the reaction vessel was filled with a mixed gas in which the volume ratio of oxygen and nitrogen was 1: 4, and 13.4 μmol of acetaldehyde was sealed. Then, visible light was irradiated from outside the reaction vessel. For irradiation with visible light, a light source device (trade name “Offical Molex® SX-UI500XQ”, manufactured by Ushio Inc.) equipped with a 500 W xenon lamp (trade name “Lanf UXL-500SX”, manufactured by Ushio Inc.) was applied to a wavelength of about 430 nm. A filter equipped with the following UV-cut filter (trade name "Y-45", made by Asahi Techno Glass) and a filter that cuts infrared light with a wavelength of about 830 nm or more (trade name "Super Coulter Filter", manufactured by Ushio Inc.) Was used as a light source. When acetaldehyde is decomposed by irradiation with visible light, carbon dioxide is generated. Therefore, the concentration of carbon dioxide is measured over time with a photoacoustic multi-gas monitor (model number “1312”, manufactured by INNOVA), and carbon dioxide calculated from the change in concentration is measured. The photocatalytic action of titanium oxide on acetaldehyde was evaluated based on the rate of formation of. The generation rate of carbon dioxide in this example was 31.2 μmol / h per 1 g of titanium oxide.
[0027]
Example 2
In a 1 L flask, 102 g of the same titanium oxysulfate hydrate used in Example 1 was dissolved in 408 g of water to prepare a titanium oxysulfate aqueous solution having a pH of about 1. Niobium hydrogen oxalate (manufactured by Mitsuwa Chemicals, Nb ₂ O ₅ 0.39 g) was added and dissolved to prepare a mixed aqueous solution. The amount of niobium in this mixed aqueous solution was 0.001 mol times with respect to titanium.
[0028]
After 300 g of water was placed in the same 1-L flask used in [Preparation of Titanium Oxide] of Example 1, the flask was cooled. The pH set value of the pH controller was set to 4, and the pH of the water was adjusted to the set value. While stirring at 400 rpm, 510.39 g of the mixed aqueous solution obtained above was added at 5 ml / min, and reacted with ammonia water supplied to the flask by a pH controller.
[0029]
The pH of the liquid in the flask was pH 3.2 to 4.9 for 5 minutes after the start of the addition of the mixed aqueous solution, and was pH 3.8 to 4.3 from 5 minutes after the start of the addition to the end of the addition. . The liquid temperature in the flask at the start of the addition was 24 ° C, and the liquid temperature at the end of the addition was 26 ° C.
[0030]
The obtained slurry was held for 1 hour with stirring, then 25% by weight aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries) was supplied, and the mixture was further stirred for 1 hour to mature the product. During this time, the temperature of the slurry was constant at 24 ° C. The total amount of aqueous ammonia supplied into the flask was 116 g, twice the stoichiometric amount of the base required to convert titanium oxysulfate to titanium hydroxide.
[0031]
The slurry containing the aged product is filtered, washed, and dried. The dried product is fired in air at 400 ° C. for 1 hour, and the fired product is washed and dried to obtain particulate anatase-type titanium oxide. Was.
[0032]
This titanium oxide was evaluated under the same conditions as in [Evaluation of activity of titanium oxide] in Example 1. The generation rate of carbon dioxide in this example was 27.6 μmol / h per 1 g of titanium oxide.
[0033]
Example 3
In a 1 L flask, 102 g of the same titanium oxysulfate hydrate used in Example 1 was dissolved in 238 g of water to prepare an aqueous solution of titanium oxysulfate having a pH of about 1. 0.15 g of indium nitrate trihydrate (manufactured by Kishida Chemical) was added to and dissolved in this aqueous solution of titanium oxysulfate, and then 46.43 g of a 31% hydrogen peroxide solution was added to obtain a red-purple mixed aqueous solution. . The amount of indium in this mixed aqueous solution was 0.001 mol times with respect to titanium.
[0034]
After 300 g of water was placed in the same 1-L flask used in [Preparation of Titanium Oxide] of Example 1, the flask was cooled. The pH set value of the pH controller was set to 6, and the pH of the water was adjusted to the set value. While stirring the content at 400 rpm, 386.58 g of the mixed aqueous solution obtained above was added to the flask at 5 ml / min, and reacted with ammonia water supplied into the flask by a pH controller.
[0035]
The pH of the liquid in the flask was 5.4 to 6.9 for 20 minutes after the addition of the mixed aqueous solution was started, and was 5.9 to 6.1 from 20 minutes after the start of the addition to the end of the addition. . The liquid temperature in the flask at the start of the addition was 24 ° C, and the liquid temperature at the end of the addition was 30 ° C.
[0036]
The obtained slurry was held for 1 hour and 10 minutes with stirring, and then 25% by weight aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was supplied, followed by further stirring for 1 hour to mature the product. During this time, the temperature of the slurry was constant at 27 ° C. The total amount of aqueous ammonia supplied into the flask was 115 g, twice the stoichiometric amount of the base required to convert titanium oxysulfate to titanium hydroxide.
[0037]
The slurry containing the aged product is filtered, washed, and dried. The dried product is fired in air at 400 ° C. for 1 hour, and the fired product is washed and dried to obtain particulate anatase-type titanium oxide. Was.
[0038]
This titanium oxide was evaluated under the same conditions as in [Evaluation of activity of titanium oxide] in Example 1. The generation rate of carbon dioxide in this example was 20.1 μmol / h per 1 g of titanium oxide.
[0039]
Example 4
In a 1 L flask, 102 g of the same titanium oxysulfate hydrate used in Example 1 was dissolved in 158 g of water to prepare an aqueous solution of titanium oxysulfate having a pH of about 1. 0.15 g of zirconium sulfate hydrate (manufactured by Wako Pure Chemical Industries) is added to and dissolved in this aqueous solution of titanium oxysulfate, and then 81.36 g of 31% hydrogen peroxide is added to obtain a red-purple mixed aqueous solution. Was. The amount of zirconium in this mixed aqueous solution was 0.001 mol times with respect to titanium.
[0040]
After 300 g of water was placed in the same 1-L flask used in [Preparation of Titanium Oxide] of Example 1, the flask was cooled. The pH set value of the pH controller was set to 7, and the pH of the water was adjusted to the set value. While stirring the content at 400 rpm, 341.51 g of the mixed aqueous solution obtained above was added at 5 ml / min into the flask, and reacted with ammonia water supplied into the flask by a pH controller.
[0041]
The pH of the liquid in the flask was pH 6.1 to 8.2 for 17 minutes from the start of the addition of the mixed aqueous solution, and was pH 6.9 to 7.0 from 17 minutes after the start of the addition to the end of the addition. . The liquid temperature in the flask at the start of the addition was 23 ° C, and the liquid temperature at the end of the addition was 32 ° C.
[0042]
The obtained slurry was held for 1 hour with stirring, then 25% by weight aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries) was supplied, and the mixture was further stirred for 1 hour to mature the product. During this time, the temperature of the slurry was constant at 28 ° C. The total amount of aqueous ammonia supplied into the flask was 115 g, twice the stoichiometric amount of the base required to convert titanium oxysulfate to titanium hydroxide.
[0043]
The slurry containing the aged product is filtered, washed, and dried. The dried product is fired in air at 400 ° C. for 1 hour, and the fired product is washed and dried to obtain particulate anatase-type titanium oxide. Was.
[0044]
This titanium oxide was evaluated under the same conditions as in [Evaluation of activity of titanium oxide] in Example 1. The generation rate of carbon dioxide in this example was 22.6 μmol / h per 1 g of titanium oxide.
[0045]
Example 5
In a 1 L flask, 102 g of the same titanium oxysulfate hydrate used in Example 1 was dissolved in 238 g of water to prepare an aqueous solution of titanium oxysulfate having a pH of about 1. 0.17 g of gallium nitrate hydrate (manufactured by Wako Pure Chemical Industries) is added and dissolved in this aqueous solution of titanium oxysulfate, and then 46.76 g of 31% hydrogen peroxide is added to obtain a red-purple mixed aqueous solution. Was. The amount of gallium in the mixed aqueous solution was 0.001 mol times with respect to titanium.
[0046]
After 300 g of water was placed in the same 1-L flask used in [Preparation of Titanium Oxide] of Example 1, the flask was cooled. The pH set value of the pH controller was set to 7, and the pH of the water was adjusted to the set value. While stirring the contents at 400 rpm, 386.93 g of the mixed aqueous solution obtained above was added at 5 ml / min, and reacted with ammonia water supplied to the flask by a pH controller.
[0047]
The pH of the liquid in the flask was 6.0 to 7.9 for 10 minutes after the addition of the mixed aqueous solution was started, and was 6.9 to 7.1 from 10 minutes after the start of the addition to the end of the addition. . The liquid temperature in the flask at the start of the addition was 25 ° C, and the liquid temperature at the end of the addition was 30 ° C.
[0048]
The obtained slurry was held for 1 hour with stirring, then 25% by weight aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries) was supplied, and the mixture was further stirred for 1 hour to mature the product. During this time, the temperature of the slurry was constant at 29 ° C. The total amount of aqueous ammonia supplied into the flask was 115 g, twice the stoichiometric amount of the base required to convert titanium oxysulfate to titanium hydroxide.
[0049]
The slurry containing the aged product is filtered, washed, and dried. The dried product is fired in air at 400 ° C. for 1 hour, and the fired product is washed and dried to obtain particulate anatase-type titanium oxide. Was.
[0050]
This titanium oxide was evaluated under the same conditions as in [Evaluation of activity of titanium oxide] in Example 1. The generation rate of carbon dioxide in this example was 14.9 μmol / h per 1 g of titanium oxide.
[0051]
Comparative Example 1
The same 1 L flask used in [Preparation of Titanium Oxide] of Example 1 was charged with an aqueous solution of titanium oxysulfate prepared by dissolving 102 g of titanium oxysulfate hydrate (manufactured by Soegawa Rikagaku) in 408 g of water. While stirring at 400 rpm, 25% by weight aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was supplied at 5 ml / min to react with an aqueous solution of titanium oxysulfate. The pH of the liquid in the flask was 0.7 for 1 minute after the start of the addition of the aqueous ammonia, and was 4 after the addition was completed. The liquid temperature in the flask at the start of the addition of the ammonia water was 62 ° C, and the liquid temperature at the end of the addition was 65 ° C. The amount of aqueous ammonia supplied into the flask was 58 g, which was one time the stoichiometric amount of the base required to convert titanium oxysulfate to titanium hydroxide.
[0052]
The slurry was filtered, washed and dried, and the obtained dried product was calcined in air at 400 ° C. for 1 hour to obtain particulate anatase-type titanium oxide.
[0053]
This titanium oxide was evaluated under the same conditions as in [Evaluation of activity of titanium oxide] in Example 1. The generation rate of carbon dioxide in this example was 0 μmol / h per 1 g of titanium oxide.
[0054]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the manufacturing method of this invention, the titanium oxide which shows the outstanding photocatalytic activity with irradiation of visible light can be obtained.
[Brief description of the drawings]
FIG. 1 is a correlation diagram of pH and solubility of zinc hydroxide.
FIG. 2 is a correlation diagram of pH and gallium hydroxide solubility.
FIG. 3 is a correlation diagram of pH and indium hydroxide solubility.
FIG. 4 is a correlation diagram of pH-zirconium hydroxide solubility.
FIG. 5 is a correlation diagram of pH-iron hydroxide solubility.

Claims (5)

A titanium compound, a group IIa element, a group IIIa element, a group Va element, a group VIa element, a group VIIa element, a group VIII element, a group Ib element, a group IIb element, a group IIIb element, a lanthanoid, silicon, germanium, tin, lead, A second component consisting of an element selected from antimony, bismuth, zirconium and hafnium or a compound thereof and a solvent are mixed, and a base is added to the mixture to form a base having a solubility of 10 ^{− of} a hydroxide of the element constituting the second component. ^A method for producing titanium oxide, comprising reacting under conditions of ⁴ g / L or less and calcining the obtained solid. The method of claim 1, wherein the titanium compound is selected from titanium trichloride, titanium tetrachloride, titanium sulfate, titanium oxychloride and titanium oxysulfate. 3. The method according to claim 1, wherein the second component comprises an element selected from zinc, zirconium, gallium, indium, iron and niobium, or a compound thereof. 3. The method according to claim 1, wherein the second component comprises an element selected from zinc and niobium or a compound thereof. The method according to any one of claims 1 to 4, wherein the base is ammonia.

Images