JP2009078264A - Visible light-responsive photocatalyst and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a titanium oxide photocatalyst having high activity in a visible light range its manufacturing method. <P>SOLUTION: The visible light-responsive photocatalyst is prepared by dispersing at least one element selected from the group consisting of platinum, silver, copper, nickel, cobalt, iron, manganese, chrome, vanadium, palladium, molybdenum and zinc on the inside and surface of a titanium oxide particle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a visible light responsive photocatalyst that exhibits a photocatalytic action when irradiated with visible light, and a method for producing the same.

  Conventional titanium oxide photocatalysts have the disadvantage that visible light cannot be used because the wavelength of light to be responsive is in the ultraviolet region. Therefore, ultraviolet rays contained in sunlight can be used outside, but ultraviolet rays such as fluorescent lamps are very weak indoors. Therefore, in order to make the titanium oxide photocatalyst work in the room, it is necessary to use black light or the like with strong ultraviolet light.

  In recent years, titanium oxide photocatalysts that respond even to light in the visible light region have been developed. For example, a method of injecting a very small amount of transition metal ions such as Cr and V into a titanium oxide photocatalyst by a magnetron sputter deposition method (see Patent Document 1), and a cation such as Cr, V, Fe, and Mn on the surface of the titanium oxide photocatalyst. There is a method of bringing a cation into contact with a medium to be contained (see Patent Document 2).

  Further, a titanium oxide photocatalyst that responds even in the visible light region has been developed by a method of doping titanium oxide with nitrogen (see Patent Documents 3 and 4) and a method of doping titanium oxide with sulfur (see Patent Document 5).

  Furthermore, a method of supporting metal fine particles on titanium oxide fine particles in the presence of a metal compound (see Patent Document 6), and a method of supporting titanium compounds by heat-treating titanium oxide fine particles in the presence of a platinum compound (see Patent Document 7). Thus, a titanium oxide photocatalyst that responds even in the visible light region has been proposed.

  Furthermore, titanium oxide responds even in the visible light region by mixing titanium oxide compounds with metal compounds to produce titanium oxide particles, and by incorporating iron ions, chromium ions and cobalt ions inside the titanium oxide particles. Photocatalysts have been proposed (see Patent Documents 8, 9, and 10).

JP-A-9-262482 JP 2000-237598 A JP 2001-205094 A JP 2002-255554 A JP 2004-143032 A JP 2000-262906 A JP 2004-143032 A JP 2002-60221 A JP-A-11-255514 JP 2000-70727 A

  However, according to the study by the present inventors, the titanium oxide photocatalyst according to the conventional technology developed so far is low in activity even though it responds under light in the visible light region.

  In view of the present situation, an object of the present invention is to provide a titanium oxide photocatalyst having high activity in the visible light region and a method for producing the same.

  As a result of studies conducted by the present inventors to solve the above-mentioned problems, in order for the titanium oxide photocatalyst to exhibit high activity with light in the visible light region, the type of substance to be contained in the titanium oxide particles is selected. The present invention has been completed by thinking that it is necessary to control the amount to be contained and that it is important to increase the surface area by reducing the particle size of the titanium oxide photocatalyst.

That is, the first invention for solving the above-described problem is
At least one element selected from the group consisting of platinum, silver, copper, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc is dispersed inside and on the surface of the titanium oxide particles. This is a visible light responsive photocatalyst.

The second invention is
The visible light responsive photocatalyst according to the first invention, wherein the element is dispersed as metal fine particles of the element.

The third invention is
The visible light responsive photocatalyst according to the first invention, wherein the element is dispersed as a compound containing the element.

The fourth invention is:
The visible light according to the first invention, wherein the element is dispersed as metal fine particles of the element inside the titanium oxide particles, and is dispersed as a compound containing the element on the surface of the titanium oxide particles. Photoresponsive photocatalyst.

The fifth invention is:
A first step of hydrolyzing a solution of the titanium compound or adding an alkali to the solution of the titanium compound to precipitate titanium hydroxide; a second step of sintering the titanium hydroxide to obtain titanium oxide particles; Have
At least one selected from the group consisting of copper, platinum, silver, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc in the first step or between the first and second steps. Add substances containing various elements,
In the second step, a mixture of titanium hydroxide and the compound is sintered, and platinum, silver, copper, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, A method for producing a visible light responsive photocatalyst, wherein at least one element selected from the group consisting of molybdenum and zinc is dispersed.

The sixth invention is:
The method for producing a visible light responsive photocatalyst according to the fifth aspect, wherein titanium chloride, titanium sulfate, titanyl sulfate, and titanium tetraisopropoxide are used as the titanium oxide compound.

The seventh invention
6. The method for producing a visible light responsive photocatalyst according to the fifth invention, wherein the substance is dispersed as metal fine particles of the element.

The eighth invention
The method for producing a visible light responsive photocatalyst according to the fifth invention, wherein the substance is dispersed as a compound containing the element.

  The visible light responsive photocatalyst of titanium oxide according to the present invention (hereinafter sometimes abbreviated as “photocatalyst” in the present invention) has a smaller particle size than a conventional photocatalyst having activity in the visible light region. Particles were obtained. As a result, the activity is higher than the conventional photocatalyst having activity in the visible light region.

  Moreover, an expensive apparatus such as a sputtering apparatus is not necessary for the production of the visible light responsive photocatalyst of titanium oxide according to the present invention, and a photocatalyst exhibiting high activity by irradiation with light in the visible light region can be produced at a low cost.

The present inventors have studied and examined the reason why the visible light responsive photocatalyst according to the prior art has low activity even though it responds under light in the visible light region.
As a result, it has been found that the photocatalytic activity is not improved even if the visible light responsive photocatalyst can absorb visible light by the substance contained in the titanium oxide particles. The reason for this was thought to be that the substance that absorbed visible light had a low electron transfer rate, so that recombination occurred in the middle of the electron transfer and no photocatalytic action was exhibited.

  On the other hand, metals such as platinum and silver have a metallic luster, but are known to be colored when they are made into fine particles. The platinum and silver particles become colored black or brown and absorb visible light. However, the method in which the metal fine particles are supported only on the surface of the titanium oxide particles has a problem that the amount of the metal fine particles is small, so that the visible light cannot be sufficiently absorbed and the photocatalytic activity under visible light is low.

Here, the present inventors have devised a method for improving the high photocatalytic activity of titanium oxide particles using the metal fine particles, paying attention to predetermined metal fine particles having a high electron transfer speed. Furthermore, it has been conceived that the metal fine particles are contained not only on the surface of the titanium oxide particles but also inside the particles, thereby sufficiently absorbing visible light.
Furthermore, the present inventors also paid attention to a predetermined colored metal compound. A method for improving the high photocatalytic activity of titanium oxide particles using the metal compound has been devised. Further, the inventors have conceived that the visible light can be sufficiently absorbed by including the metal compound not only on the surface of the titanium oxide particles but also inside the particles.

  Hereinafter, the visible light responsive photocatalyst of titanium oxide particles according to the present invention will be described in the order of titanium oxide particles and added metal elements.

(Titanium oxide particles)
There are several processes for producing titanium oxide particles according to the present invention.
For example, when titanium chloride, titanium sulfate, and titanyl sulfate are dissolved in water to form a solution, and an aqueous sodium carbonate solution or an aqueous sodium hydroxide solution is added to the solution, titanium hydroxide is obtained as a precipitate. When using titanium chloride, an aqueous sodium carbonate solution or an aqueous sodium hydroxide solution is added until the pH of the solution reaches 10 or higher. However, when titanium chloride is dissolved in water, white smoke is generated and heat is generated. Further, when a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution is added to an aqueous solution in which titanium chloride or the like is dissolved, heat is generated.
The obtained precipitate is filtered, washed 5-6 times with pure water to remove sodium chloride and sodium sulfate contained in the precipitate, and then dried to obtain titanium hydroxide. When the obtained titanium hydroxide is sintered at about 380 ° C. and the agglomerates are pulverized into powder, titanium oxide particles exhibiting photocatalytic action are obtained.

When using titanium chloride as the titanium raw material, titanium (III) chloride and titanium (IV) chloride
Either of these can be used. However, it is convenient to use an aqueous titanium tetrachloride solution that is easy to handle. When titanium chloride is used, the reason why the aqueous sodium carbonate solution or the aqueous sodium hydroxide solution is added until the pH of the solution becomes 10 or more is related to the fact that the current point of titanium oxide is around pH 6. This is because when titanium chloride is used, particles in which titanium oxide is negatively charged can be produced under conditions where the pH is 10 or more, and the dye is easily adsorbed.

  When titanium tetraisopropoxide is used as the titanium raw material, water is added to the titanium tetraisopropoxide for hydrolysis to precipitate titanium hydroxide. After the titanium hydroxide is dried, it is sintered at, for example, 380 ° C., and the agglomerates are pulverized into powder to obtain titanium oxide particles exhibiting photocatalytic action.

  For example, a titanium chloride aqueous solution is mixed with one or more salts selected from copper chloride, nickel chloride, cobalt chloride, iron chloride, manganese chloride, chromium chloride, and palladium chloride to form a solution. An alkali is added to the aqueous solution to precipitate one or more selected from titanium hydroxide, copper hydroxide, nickel hydroxide, cobalt hydroxide, iron hydroxide, manganese hydroxide, chromium hydroxide, and palladium hydroxide. I let you. Alkali was added until the pH of the solution reached 10 or higher. The precipitate is dried and then sintered, for example, at 380 ° C., and the titanium oxide powder uniformly contains at least one component selected from copper, nickel, cobalt, iron, manganese, chromium and palladium inside and on the surface. I was able to make. As the alkali, an aqueous sodium carbonate solution or an aqueous sodium hydroxide solution can be used.

  For example, when adding silver nitrate to titanium sulfate or titanium tetraisopropoxide, a grayish purple powder was obtained when the sintering temperature was about 380 ° C. As a result of examining the photocatalytic activity in the visible light region, it showed a higher activity than the conventionally known catalysts. Furthermore, even when sintered at 380 ° C., which is lower than the decomposition temperature of silver nitrate, a gray powder was obtained.

Further, for example, titanium tetraisopropoxide is used as a titanium raw material, and one or more compounds selected from copper, platinum, silver, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc are mixed. In this case, these compounds may be dissolved in ethanol in advance, or after precipitation of titanium hydroxide, these compounds may be dissolved in ethanol and mixed with titanium hydroxide.
Even in the method of evaporating ethanol from a mixture of titanium raw material and these compounds and sintering the residual material at 350 to 800 ° C. to form a powder, copper, platinum, silver, nickel, A substance in which the components of cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc are uniformly contained can be obtained. Substances in which the components of copper, platinum, silver, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc are uniformly contained inside and on the surface of the titanium oxide particles have photocatalytic activity in the visible light region. Show.

(Metal elements to be added)
<platinum>
Platinum is a transition metal with a low ionization tendency, and colored metal fine particles are obtained.
When mixing a titanium raw material and a platinum compound, the platinum compound and titanium hydroxide can be coprecipitated by mixing the platinum compound with titanium chloride, titanium sulfate, and titanyl sulfate. . When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 350 to 800 ° C. into a powder, a substance in which ultrafine metal particles of silver or platinum are uniformly contained inside and on the surface of the powder is formed. A substance in which ultrafine metal particles of silver or platinum are uniformly contained in and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  Moreover, once titanium hydroxide is generated, an aqueous solution of a platinum compound is added to the titanium hydroxide, mixed well and dried, and sintered at 300 to 800 ° C., more preferably 300 to 400 ° C., A method of forming a powder is also preferable. Also by this method, a substance which contains silver and platinum ultrafine particles of silver and platinum uniformly in the inside and surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

  As the platinum compound, chloroplatinic acid may be dissolved in water. In addition, ammonium chloroplatinate, potassium chloroplatinate, sodium chloroplatinate, platinum hydroxide, sodium platinumate, platinum chloride (II), platinum chloride (IV), platinum bromide, platinum sulfate, platinum oxide (IV) Platinum oxide (II) or platinum powder can also be used.

  For example, chloroplatinic acid decomposes at 370 ° C. In the course of producing titanium oxide particles, chloroplatinic acid was mixed and sintered at 380 ° C., and a brown-colored titanium oxide powder uniformly containing metal platinum inside and on the surface could be produced. As a result of examining the photocatalytic activity in the visible light region, it showed higher activity than the conventionally known catalysts. Further, when the sintering temperature was 600 ° C., a gray powder was obtained. As a result of examining the photocatalytic activity in the visible light region, the gray powder was almost as active as a conventionally known catalyst.

<Silver>
Silver is a metal that is a transition metal and has a low ionization tendency, and colored metal fine particles can be obtained.
When mixing a titanium raw material and a silver compound, the silver compound and hydroxide are mixed by mixing the silver compound with titanium chloride, titanium sulfate, and titanyl sulfate in the production process of the titanium oxide particles. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 300 to 800 ° C., more preferably 300 to 400 ° C., to obtain a powder, a substance in which silver metal ultrafine particles are uniformly contained inside and on the surface is formed. A substance in which silver metal ultrafine particles are uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  In addition, once titanium hydroxide is generated, an aqueous solution of a silver compound is added to the titanium hydroxide, mixed and dried, and sintered at 300 to 800 ° C, more preferably 300 to 400 ° C. A method of forming a powder is also preferable. Also by this method, a silver metal ultrafine particle is uniformly contained inside and on the surface of the powder, and a substance exhibiting photocatalytic activity in the visible light region can be obtained.

  As the silver compound, silver nitrate may be dissolved in water. Other silver raw materials include silver fluoride, silver chloride, silver bromide, silver iodide, silver sulfate, silver metaphosphate, silver acetate, silver nitrite, silver sulfite, silver chlorate, silver cyanide, silver carbonate, thio Silver sulfate, silver sulfide, silver phosphate, silver dihydrogen phosphate, disilver hydrogen phosphate, silver oxide, and silver powder can also be used.

  For example, silver nitrate has a decomposition temperature of 444 ° C., and silver oxide has a decomposition temperature of 300 ° C. In the titanium oxide particle manufacturing process, titanium hydroxide is precipitated by adding alkali using titanium chloride as a raw material. When silver nitrate was dissolved in water and the titanium hydroxide precipitate was mixed, dried and sintered at 380 ° C., titanium oxide powder containing metal silver uniformly inside and on the surface could be produced. Since the metallic silver contained on the surface is contained in the form of ultrafine particles, the prepared powder is gray purple and can absorb visible light.

<copper>
Copper is a metal which is a transition metal and has a low ionization tendency, and colored metal fine particles can be obtained.
When mixing the titanium raw material and the copper compound, the copper compound and the hydroxide are mixed by mixing the copper compound with titanium chloride, titanium sulfate, and titanyl sulfate in the production process of the titanium oxide particles. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 300 to 800 ° C., more preferably at 300 to 400 ° C., to obtain a powder, a substance in which copper oxide is uniformly contained inside and on the surface of the powder is formed. A substance in which copper oxide is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  In addition, once titanium hydroxide is generated, an aqueous solution of a copper compound is added to the titanium hydroxide, thoroughly mixed and dried, and sintered at 300 to 800 ° C., more preferably 300 to 400 ° C., A method of forming a powder is also preferable. Also by this method, a substance that contains a copper oxide uniformly in and on the surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

  As the copper compound, copper (II) chloride may be dissolved in water. In addition, copper sulfate (II), copper acetate (II), copper nitrate (II), copper hydroxide (II), copper fluoride (II), copper sulfide (II), copper oxide (II) can also be used. it can. Furthermore, monovalent copper chloride (I), copper hydroxide (I), copper fluoride (I), copper sulfide (I), copper oxide (I), and copper powder can also be used.

  For example, copper (II) chloride decomposes at 498 ° C. Copper (II) hydroxide decomposes into copper oxide at 360 ° C. When copper chloride (II) is mixed with titanium chloride and an alkali is added, a mixture of titanium hydroxide and copper hydroxide coexists. This precipitate was sintered at 380 ° C., and a titanium oxide powder containing copper oxide uniformly inside and on the surface could be produced.

  As a result of examining the photocatalytic activity in the visible light region, it was active in the visible light region when copper chloride (II) was mixed with titanium chloride and the mixture of titanium hydroxide and copper hydroxide was sintered at 350 to 800 ° C. showed that.

  Further, for example, titanium tetraisopropoxide was mixed with copper (II) chloride and sintered at 550 ° C., and titanium oxide powder containing a copper compound uniformly inside and on the surface could be produced. As a result of examining the photocatalytic activity in the visible light region, when sintered at 700 ° C., a light green powder in which the copper compound is uniformly dispersed inside and on the surface of the titanium oxide powder is obtained, and in the visible light region, High activity was shown.

<nickel>
When mixing a titanium raw material and a nickel compound, the nickel compound and the hydroxide are mixed by mixing the nickel compound with titanium chloride, titanium sulfate, and titanyl sulfate in the production process of the titanium oxide particles. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the dried precipitate at 300 to 800 ° C., more preferably at 300 to 400 ° C., to obtain a powder, a substance in which a nickel compound is uniformly contained inside and on the surface of the powder is formed. A substance in which a nickel compound is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

In addition, once titanium hydroxide is generated, an aqueous solution of a nickel compound is added to the titanium hydroxide, mixed and dried, and sintered at 300 to 800 ° C, more preferably 300 to 400 ° C. A method of forming a powder is also preferable. Also by this method, a nickel compound is uniformly contained inside and on the surface of the powder, and a substance exhibiting photocatalytic activity in the visible light region can be obtained.

  As the nickel compound, nickel chloride (II), nickel sulfate (II), nickel nitrate (II), nickel hydroxide (II), nickel oxide (II), or nickel powder can be used.

  For example, nickel hydroxide decomposes at 230 ° C. to nickel oxide. Nickel chloride is mixed with titanium chloride, and alkali is added to precipitate titanium hydroxide and nickel hydroxide. When titanium chloride is used, alkali is added until the pH of the solution becomes 10 or more. Sintered at 380 ° C., titanium oxide powder containing nickel oxide uniformly inside and on the surface could be made. The titanium oxide powder containing nickel oxide uniformly showed high activity in the visible light region.

<cobalt>
When mixing a titanium raw material and a cobalt compound, the cobalt compound and hydroxylated by mixing the cobalt compound with titanium chloride, titanium sulfate, and titanyl sulfate in the production process of the titanium oxide particles. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 300 to 800 ° C., more preferably at 300 to 400 ° C., to obtain a powder, a substance in which ultrafine metal particles of cobalt are uniformly contained inside and on the surface of the powder is formed. A substance in which cobalt metal ultrafine particles are uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  In addition, once titanium hydroxide is generated, an aqueous solution of a cobalt compound is added to the titanium hydroxide, mixed well, dried, and sintered at 300 to 800 ° C, more preferably 300 to 400 ° C. A method of forming a powder is also preferable. Also by this method, a substance which contains a cobalt compound uniformly in and on the surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

Cobalt compounds include cobalt chloride (II), cobalt sulfate (II), cobalt sulfate (III), cobalt nitrate (II), cobalt hydroxide (II), cobalt oxide (II), cobalt oxide (III), cobalt Powder can be used.

<iron>
When mixing the titanium raw material and the iron compound, the iron compound and the hydroxide are mixed by mixing the iron compound with titanium chloride, titanium sulfate, and titanyl sulfate in the production process of the titanium oxide particles. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 300 to 800 ° C., more preferably at 300 to 400 ° C., to form a powder, a substance in which an iron compound is uniformly contained can be formed inside and on the surface of the powder. A substance in which an iron compound is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  Further, once titanium hydroxide is generated, an aqueous solution of an iron compound is added to the titanium hydroxide, mixed well, dried, and sintered at 300 to 800 ° C, more preferably 300 to 400 ° C. A method of forming a powder is also preferable. Also by this method, a substance that contains iron compounds uniformly in and on the surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

Iron compounds include iron chloride (II), iron chloride (III), iron sulfate (II), iron sulfate (III), iron nitrate (II), iron nitrate (III), iron hydroxide (II), water Iron (III) oxide, iron (II) oxide, iron (III) oxide, and iron powder can be used.

For example, iron (III) chloride has a melting point of 300 ° C., and iron (III) hydroxide decomposes into iron (III) oxide at 350 to 400 ° C. Mix iron chloride (III) with titanium chloride, add alkali to precipitate titanium hydroxide and iron (III) hydroxide, and sinter at 380 ° C to uniformly distribute iron (III) oxide inside and on the surface The titanium oxide powder contained in The titanium oxide powder exhibits high catalytic activity in the visible light region.

<manganese>
When mixing a titanium raw material and a manganese compound, in the process of producing titanium oxide particles, the manganese compound is mixed with titanium chloride, titanium sulfate, and titanyl sulfate, so that the manganese compound and the hydroxide are mixed. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 300 to 800 ° C., more preferably at 300 to 400 ° C., to obtain a powder, a substance in which a manganese compound is uniformly contained inside and on the surface of the powder is formed. A substance in which a manganese compound is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  In addition, once titanium hydroxide is generated, an aqueous solution of a manganese compound is added to the titanium hydroxide, mixed well and dried, and sintered at 300 to 800 ° C, more preferably 300 to 400 ° C. A method of forming a powder is also preferable. Also according to this method, a substance that contains a manganese compound uniformly in and on the surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

As manganese compounds, manganese raw materials are manganese chloride (II), manganese sulfate (II), manganese sulfate (III) manganese nitrate (II), manganese hydroxide (II), manganese oxide (II
), Manganese (III) oxide, manganese (IV) oxide, and manganese powder.

<chromium>
When mixing the titanium raw material and the chromium compound, the chromium compound and the hydroxide are mixed by mixing the chromium compound with titanium chloride, titanium sulfate and titanyl sulfate in the production process of the titanium oxide particles. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 2-3 times to remove sodium sulfate and sodium chloride contained therein, and then dried. By sintering the precipitate after drying at 300 to 800 ° C., more preferably at 300 to 400 ° C., to form a powder, a substance in which a chromium compound is uniformly contained inside and on the surface of the powder is formed. A substance in which a chromium compound is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  In addition, once titanium hydroxide is generated, an aqueous solution of a chromium compound is added to the titanium hydroxide, mixed well and dried, and sintered at 300 to 800 ° C., more preferably 300 to 400 ° C., A method of forming a powder is also preferable. Also by this method, a substance which contains a chromium compound uniformly in the powder and on the surface and exhibits photocatalytic activity in the visible light region can be obtained.

Chromium compounds include chromium (II) chloride, chromium (III) chloride, and chromium (II) sulfate.
, Chromium (III) sulfate, chromium (III) nitrate, chromium hydroxide (II), chromium hydroxide (III)
Chromium (II) oxide, chromium (III) oxide and chromium powder can be used.

<vanadium>
When mixing a titanium raw material and a vanadium compound, the vanadium compound is mixed with the titanium oxide, titanium sulfate, and titanyl sulfate in the production process of the titanium oxide particles. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 300 to 800 ° C., more preferably at 300 to 400 ° C., to obtain a powder, a substance in which the vanadium compound is uniformly contained inside and on the surface of the powder is formed. A substance in which a vanadium compound is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  In addition, once titanium hydroxide is generated, an aqueous solution of a vanadium compound is added to the titanium hydroxide, mixed well, dried, and sintered at 300 to 800 ° C, more preferably 300 to 400 ° C. A method of forming a powder is also preferable. Also by this method, a substance which contains a vanadium compound uniformly inside and on the surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

Examples of vanadium compounds include vanadium (III) chloride, sodium metavanadate,
Vanadium pentoxide and vanadium powder can be used.

<palladium>
When mixing a titanium raw material and a palladium compound, the palladium compound and titanium hydroxide are mixed with the palladium compound, titanium chloride, and titanium sulfate in the production process of the titanium oxide particles. Can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. Sintering the precipitate after drying at 300 to 800 ° C., more preferably 300 to 400 ° C., to obtain a powder in which a palladium compound is uniformly contained inside and on the surface of the powder. A substance in which a palladium compound is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

  Moreover, once titanium hydroxide is generated, an aqueous solution of a palladium compound is added to the titanium hydroxide, mixed well and dried, and sintered at 300 to 800 ° C., more preferably 300 to 400 ° C., A method of forming a powder is also preferable. Also by this method, a substance that contains palladium metal ultrafine particles uniformly in and on the surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

  As the palladium compound, palladium chloride (II), palladium sulfate (II), palladium nitrate (II), palladium oxide (II), and palladium powder can be used.

<molybdenum>
When mixing a titanium raw material and a molybdenum compound, the molybdenum compound is mixed with titanium chloride, titanium sulfate, and titanyl sulfate in the course of manufacturing the titanium oxide particles, so that the molybdenum compound and the hydroxide are mixed. Titanium can be co-precipitated. When using titanium chloride, alkali is added until the pH of the solution reaches 10 or higher. The obtained precipitate is filtered and washed with pure water 5 to 6 times to remove sodium sulfate and sodium chloride, and then dried. By sintering the precipitate after drying at 300 to 800 ° C. to form a powder, a substance in which the molybdenum compound is uniformly contained inside and on the surface of the powder is formed. A substance in which a molybdenum compound is uniformly contained inside and on the surface of the powder exhibits photocatalytic activity in the visible light region.

In addition, once titanium hydroxide is generated, an aqueous solution of a molybdenum compound is added to the titanium hydroxide, mixed well and dried, and sintered at 300 to 800 ° C, more preferably 300 to 400 ° C. A method of forming a powder is also preferable. Also by this method, a substance that contains molybdenum metal ultrafine particles uniformly inside and on the surface of the powder and exhibits photocatalytic activity in the visible light region can be obtained.

The molybdenum compounds include molybdenum chloride (V), molybdenum oxide (IV), molybdenum oxide (VI), molybdate (VI), hexaammonium heptamolybdate, disodium molybdate (IV), molybdenum sulfide (IV), Molybdenum carbide and molybdenum powder can be used.

<zinc>
Zinc is a metal that has a large ionization tendency and is easily oxidized.
Zinc compounds are white and do not absorb visible light. On the other hand, zinc powder is gray and absorbs visible light. Therefore, when titanium chloride is used after producing titanium hydroxide, alkali is added until the pH of the solution becomes 10 or more. A method in which zinc is added to the titanium hydroxide, mixed well, dried, sintered at 300 to 800 ° C., more preferably 300 to 400 ° C., and powdered is preferred. By this method, a substance that contains ultrafine zinc particles uniformly in the powder and exhibits photocatalytic activity in the visible light region can be obtained.

Zinc powder can be used as zinc.
For example, in the production process of titanium oxide particles, zinc powder was mixed and sintered at 380 ° C. to produce a gray-colored titanium oxide powder uniformly containing metallic zinc inside. As a result of examining the photocatalytic activity in the visible light region, it showed higher activity than the conventionally known catalysts.

  The mixing ratio of copper, platinum, silver, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc to titanium oxide particles is preferably in the range of 0.1 to 10% by weight. Furthermore, the mixing ratio of these copper, platinum, silver, nickel, cobalt, manganese, chromium, vanadium, palladium, molybdenum, and zinc to the titanium oxide particles is more preferably 1 to 5% by weight. On the other hand, the mixing ratio of iron to titanium oxide particles is optimally 5 to 20% by weight.

  As described above, when a metal compound is mixed in the production process of titanium oxide particles, the metal compound is contained inside the titanium oxide particles. When finally sintered, titanium oxide particles containing metal fine particles were formed not only on the surface but also inside, and it was possible to absorb visible light sufficiently, thereby enhancing the activity.

Hereinafter, the present invention will be specifically described with reference to examples.
[Example 1]
(Sample preparation)
Put 1.5 L of water in a 2 L beaker and gradually add 5 mL of titanium (IV) chloride. Next, 90 mL of a sodium carbonate aqueous solution having a concentration of 1 mol / L was added little by little to precipitate titanium hydroxide. Since titanium chloride is used, an aqueous sodium carbonate solution was added until the pH of the solution reached 10 or higher. In addition, when diluting titanium (IV) with water, it generates intense smoke and generates heat. If sodium carbonate aqueous solution is added here, it will generate | occur | produce further. Therefore, the addition operation was gradually performed while cooling the solution with ice water in the draft and stirring the solution. The produced precipitate was filtered using a suction funnel, pure water was added to the resulting titanium hydroxide precipitate, and the mixture was thoroughly stirred, followed by suction filtration again. This operation was repeated 6 times to remove sodium chloride in the titanium hydroxide precipitate.

  0.06 g of silver nitrate was dissolved in 20 mL of water, and a precipitate of titanium hydroxide from which sodium chloride was removed was added and stirred. Next, the stirred product was left at 90 ° C. for 15 hours, and water was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a gray colored powder (Sample A).

(Dye solution decomposition experiment)
In order to examine the photocatalytic action of sample A, a dye solution decomposition experiment using sample A was performed. Here, since methylene blue as a dye has absorbance at 664 nm and can measure the dye concentration, it was used in the decomposition experiment of the dye solution.

40 mL of methylene blue having an initial concentration of 5 mg / L was placed in a glass sample tube, 30 mg of Sample A was added, and the mixture was stirred with a magnetic stirrer for 30 minutes without irradiating light to obtain a sample for decomposition experiment.
Here, for comparison, 30 mg of titanium oxide photocatalyst powder of a commercial product (visible light-responsive titanium oxide photocatalyst (MPT-623): hereinafter referred to as a commercial product) manufactured by Ishihara Sangyo Co., Ltd. was prepared, and a sample was prepared. Methylene blue was mixed in the same manner as in A, and the mixture was stirred for 30 minutes without irradiating light with a magnetic stirrer to prepare a sample for decomposition experiment. At the start of stirring (30 minutes before irradiation), 10 minutes after stirring (20 minutes before irradiation), and 30 minutes after stirring (irradiation 0 minutes), a part of the sample solution for experiment was taken and a small centrifuge (FB-4000). Was centrifuged at 12,000 rpm for 4 minutes to separate and remove solids. The absorbance at 664 nm of the experimental sample solution after centrifugation was measured.
On the other hand, as a light source, visible light was prepared by passing light from a 150 W xenon lamp through a UV filter L-42 and a water filter for cutting heat rays.
The sample for decomposition experiment was irradiated with the visible light for 90 minutes. Then, after 30 minutes, 60 minutes, and 90 minutes after irradiation, a part of the sample solution for decomposition experiment was taken and centrifuged at 12,000 rpm for 4 minutes using a small centrifuge (FB-4000) to separate the solid content. Removed. The absorbance at 664 nm was measured for the sample solution for decomposition experiment after centrifugation. The experimental results are shown in Table 1.

Here, since the titanium oxide catalyst not only decomposes the pigment but also adsorbs it, a dark experiment was performed in which the same operation was performed except that no visible light was irradiated in order to clarify the adsorbed component.
The experimental results are shown in Table 1.

In both Sample A and the commercial product, the concentration of methylene blue dye decreased rapidly within 20 minutes before irradiation. This is considered to be a result of the methylene blue dye adsorption by the titanium oxide powder. Regarding the methylene blue dye concentration for 20 minutes before irradiation, the sample A is lower than the commercial product.

Here, FIG. 1 is a graph in which the horizontal axis represents the light irradiation time (elapsed time in the dark experiment), the vertical axis represents the concentration of methylene blue, and the vertical axis represents the logarithm plot for Sample A and a commercial product. It is. From the slope of the graph, the decomposition rate of methylene blue was analyzed. The time for methylene blue to reach a concentration of 0.8 mg / L is 30 minutes or less for sample A, but 90 minutes or more is required for commercially available products. The performance of the sample A was found to be superior to that of a commercially available product when the adsorption performance and the decomposition performance were comprehensively judged. The solution after 90 minutes of the dark experiment was only lightly adsorbed and faded in color, but remained methylene blue blue. The solution after 90 minutes of the light irradiation test turned blue-purple due to decomposition of methylene blue. The discoloration is caused by a colored reaction intermediate such as Azure B or Azure A, which is a decomposition product of methylene blue, which has a greater contribution of absorption around 600 nm than absorption at a wavelength of 664 nm (hereinafter simply referred to as “reaction intermediate”). There is an influence. It was confirmed from the change in the absorption waveform by measuring the absorption spectrum.
Furthermore, when 15 mL of methylene blue having an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of Sample A was added and irradiated with visible light for 60 minutes while stirring with a magnetic stirrer, it turned completely white. I was able to confirm that it was happening. As a control experiment, ST-01 (manufactured by Ishihara Sangyo Co., Ltd.), which is not a visible light responsive photocatalyst, was used to confirm that methylene blue color did not disappear.
Furthermore, in FIG. 1, the light irradiation test result of the sample according to the example is indicated by ● and a solid line, the dark experiment test result is indicated by ◆ and a long broken line, and the light irradiation test result of a commercial product is indicated by ■ and a short broken line. The dark test results are indicated by ▲ and a one-dot chain line. The same applies to FIGS. 2 to 14 below.

[Example 2]
(Sample preparation)
Using a 500 mL beaker, 0.6 g of silver nitrate was dissolved in 200 mL of ethanol to obtain a solution. To this solution, 25 mL of titanium tetraisopropoxide was added and stirred with a magnetic stirrer. When 1 mL of water was added little by little to the stirred product, titanium hydroxide precipitated. Thereafter, the precipitate was left at 70 ° C. for 12 hours, and ethanol was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours, and further sintered at 500 ° C. for 1 hour to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a grayish purple-colored powder (Sample B).

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L was placed in a glass sample tube, 30 mg of Sample B was added, and stirred with a magnetic stirrer to obtain a sample for decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 2.

  In both Sample B and the commercial product, the rapid decrease in the methylene blue dye concentration within 20 minutes before irradiation is considered to be the result of adsorption with titanium oxide powder, as in Example 1. And 20 minutes before the said irradiation, the sample B containing the silver component inside lowers the concentration of methylene blue than the commercially available product.

As a result after 90 minutes, the performance of the sample B exceeds the performance of the commercial product.
Here, FIG. 2 is a graph in which the relationship between the irradiation time and the concentration of methylene blue is logarithmically plotted for Sample B and a commercial product. When the decomposition rate of methylene blue was analyzed from the slope of the graph and the adsorption performance and the decomposition performance were comprehensively determined, it was found that the performance of the sample B exceeded that of the commercial product. The solution after 90 minutes of the light irradiation test turned blue-violet. Furthermore, when 15 mL of methylene blue having an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of Sample B was added and irradiated with visible light for 60 minutes while stirring with a magnetic stirrer, methylene blue was completely whitened. It was confirmed that decomposition of the colored methylene blue reaction intermediate occurred.

[Example 3]
(Sample preparation)
In the same manner as in Example 1, a titanium hydroxide precipitate from which sodium chloride was removed was prepared.
A solution was prepared by dissolving 0.05 g of chloroplatinic acid in 20 mL of water. To this chloroplatinic acid solution, the prepared titanium hydroxide precipitate from which sodium chloride was removed was added and stirred. Next, the precipitate was left at 90 ° C. for 15 hours, and water was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a brown colored powder (Sample C).

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L was placed in a glass sample tube, 30 mg of Sample C was added, and stirred with a magnetic stirrer to obtain a sample for decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 3.

  In both Sample C and the commercial product, the rapid decrease in the methylene blue dye concentration within 20 minutes before irradiation is considered to be the result of adsorption by the titanium oxide powder as in Example 1.

The result after 90 minutes indicates that the performance of the sample C exceeds that of the commercial product.
Here, FIG. 3 is a graph obtained by logarithmically plotting the relationship between the irradiation time and the concentration of methylene blue for the sample C and the commercial product. From the slope of the graph, when the decomposition rate of methylene blue was analyzed and the adsorption performance and the decomposition performance were comprehensively determined, it was found that the performance of the sample C exceeded that of the commercial product. The solution after 90 minutes of the light irradiation test turned blue-violet. Furthermore, when 15 mL of methylene blue having an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of sample C was added and irradiated with visible light for 60 minutes while stirring with a magnetic stirrer, methylene blue was completely whitened. It was confirmed that decomposition of the colored methylene blue reaction intermediate occurred.

[Example 4]
(Sample preparation)
Using a 500 mL beaker, 0.36 g of chloroplatinic acid was dissolved in 200 mL of ethanol to obtain a solution. Thereafter, the same operation as in Example 2 was performed, and the obtained agglomerates were pulverized in a mortar to obtain a brown colored powder (Sample D).

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L was placed in a glass sample tube, 30 mg of Sample D was added, and stirred with a magnetic stirrer to prepare a sample for decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 4. Here, for comparison, 30 mg of a commercially available titanium oxide photocatalyst powder was prepared, and methylene blue was mixed and stirred in the same manner as Sample D to prepare a sample for decomposition experiment.

  In both Sample D and the commercial product, the rapid decrease in the methylene blue dye concentration within 20 minutes before irradiation is considered to be the result of adsorption by the titanium oxide powder as in Example 1. About the same result was obtained with Sample D containing platinum on the inside and on the surface and a commercially available product for 20 minutes before irradiation.

As a result after 90 minutes, the performance of the sample D exceeds the performance of the commercial product.
Here, FIG. 4 is a graph obtained by logarithmically plotting the relationship between the irradiation time and the concentration of methylene blue for the sample D and the commercial product. From the slope of the graph, when the decomposition rate of methylene blue was analyzed and the adsorption performance and the decomposition performance were comprehensively determined, it was found that the performance of the sample D exceeded that of the commercial product. The solution after 90 minutes of the light irradiation test turned blue-violet. Further, when 15 mL of methylene blue having an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of sample D was added and irradiated with visible light for 60 minutes while stirring with a magnetic stirrer, methylene blue was completely whitened. It was confirmed that decomposition of the colored methylene blue reaction intermediate occurred.

[Example 5]
(Sample preparation)
Using a 500 mL beaker, 0.27 g of copper (II) chloride was dissolved in 200 mL of ethanol to obtain a solution. To this solution, 25 mL of titanium tetraisopropoxide was added and stirred with a magnetic stirrer. When 1 mL of water was added little by little to the stirred product, titanium hydroxide precipitated. Thereafter, the precipitate was left at 70 ° C. for 12 hours, and ethanol was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours, and further sintered at 500 ° C. for 1 hour to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a grayish purple-colored powder (Sample E).

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 10 mg / L was placed in a glass sample tube, 10 mg of sample E colored light green was added, and stirred with a magnetic stirrer to prepare a sample for decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 5.

  In both sample E and the commercial product, the rapid decrease in methylene blue dye concentration within 20 minutes before irradiation is considered to be the result of adsorption by titanium oxide powder as in Example 1.

The result after 90 minutes indicates that the sample E exceeds the performance of the commercial product.
Here, FIG. 5 is a graph in which the relationship between the irradiation time and the concentration of methylene blue is logarithmically plotted for the sample E and the commercial product. From the slope of the graph, when analyzing the decomposition rate of methylene blue, it was found that the performance of sample E was higher than that of a commercially available product when the adsorption performance and the decomposition performance were comprehensively judged. The solution after 90 minutes of the light irradiation test turned blue-violet. Furthermore, when 15 mL of methylene blue having an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of sample E was added and irradiated with visible light for 60 minutes while stirring with a magnetic stirrer, methylene blue was completely whitened. It was confirmed that decomposition of the colored methylene blue reaction intermediate occurred.

[Example 6]
(Sample preparation)
1.5 L of water was put into a 2 L beaker, 0.06 g of copper (II) chloride was added and dissolved to obtain a solution. To the solution, 5 mL of titanium (IV) chloride was gradually added. Next, 90 mL of a sodium carbonate aqueous solution having a concentration of 1 mol / L was gradually added to the solution to precipitate titanium hydroxide. Sodium carbonate aqueous solution was added until the pH of the solution reached 10 or more. In addition, when diluting titanium (IV) with water, it generates intense smoke and generates heat. If sodium carbonate aqueous solution is added here, it will generate | occur | produce further. Therefore, the addition operation was gradually performed while cooling the solution with ice water in the draft and stirring the solution. The produced precipitate was filtered using a suction funnel, pure water was added to the resulting titanium hydroxide precipitate, and the mixture was thoroughly stirred, followed by suction filtration again. This operation was repeated 7 times to remove sodium chloride in the titanium hydroxide precipitate.

  Next, the precipitate was left at 90 ° C. for 10 hours, and water was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours to obtain agglomerates. The obtained agglomerates were pulverized with a mortar to obtain a light green colored powder (Sample F).

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 10 mg / L was put into a glass sample tube, 10 mg of sample F colored light green was added, and stirred with a magnetic stirrer to prepare a sample for decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 6.

  In both Sample F and the commercial product, the rapid decrease in the methylene blue dye concentration within 20 minutes before irradiation is considered to be the result of adsorption with titanium oxide powder, as in Example 1. And 20 minutes before the said irradiation, the sample F which contains the compound of copper inside has lowered the density | concentration of methylene blue from the commercial item.

The result after 90 minutes shows that the sample F exceeds the performance of the commercial product.
Here, FIG. 6 is a graph in which the relationship between the irradiation time and the concentration of methylene blue is logarithmically plotted for the sample F and a commercial product. From the slope of the graph, when the decomposition rate of methylene blue was analyzed and the adsorption performance and the decomposition performance were comprehensively determined, it was found that the performance of the sample F exceeded that of the commercial product. The solution after 90 minutes of the light irradiation test turned blue-violet. Furthermore, when 15 mL of methylene blue with an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of sample F was added, and when light was irradiated for 60 minutes while stirring with a magnetic stirrer, methylene blue decomposed because it turned completely white Furthermore, it was confirmed that decomposition of the colored methylene blue reaction intermediate occurred.

[Example 7], [Example 8]
(Sample preparation)
Into a 2 L beaker, 1.5 L of water was added, and 0.06 g of nickel (II) chloride [Example 7] or cobalt chloride (II) [Example 8] was added and dissolved to obtain a solution. To the solution, 5 mL of titanium (IV) chloride was gradually added. Next, 90 mL of a sodium carbonate aqueous solution having a concentration of 1 mol / L was gradually added to the solution to precipitate titanium hydroxide. Sodium carbonate aqueous solution was added until the pH of the solution reached 10 or more. In addition, when diluting titanium (IV) with water, it generates intense smoke and generates heat. If sodium carbonate aqueous solution is added here, it will generate | occur | produce further. Therefore, the addition operation was gradually performed while cooling the solution with ice water in the draft and stirring the solution. The produced precipitate was filtered using a suction funnel, pure water was added to the resulting titanium hydroxide precipitate, and the mixture was thoroughly stirred, followed by suction filtration again. This operation was repeated 7 times to remove sodium chloride in the titanium hydroxide precipitate.

  Next, the precipitate was left at 90 ° C. for 10 hours, and water was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a light green colored powder (Sample G) [Example 7] or a light blue colored powder (Sample H) [Example 8].

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L is placed in a glass sample tube, and 30 mg of Sample G [Example 7] colored pale yellowish green or Sample H [Example 8] colored pale blue is magnetically added. The sample was stirred with a stirrer and used as a sample for decomposition experiments. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 7 and Table 8.

As a result after 18 minutes, the performance of the sample G [Example 7] and the sample H [Example 8] exceeds the performance of the commercial product.
Here, FIG. 7 is a graph in which the relationship between the irradiation time and the methylene blue concentration is logarithmically plotted for the sample G and the commercial product, and FIG. 8 is the irradiation time and the methylene blue concentration for the sample H and the commercial product. Is a logarithmic plot of the relationship with. When the decomposition rate of methylene blue is analyzed from the slope of the graph and the adsorption performance and the decomposition performance are comprehensively determined, the performance of the sample G [Example 7] exceeds that of a commercially available product, and the sample H [Example] It was found that the decomposition performance of 8] exceeded that of the commercial product. The solution after 90 minutes of the light irradiation test turned blue-violet. Further, 15 mL of methylene blue having an initial concentration of 2 mg / L was placed in two 30 mL glass sample tubes, and 40 mg of each of Sample G [Example 7] and Sample H [Example 8] was added and stirred with a magnetic stirrer. When visible light was irradiated for a minute, both Sample G [Example 7] and Sample H [Example 8] became completely white, so that methylene blue was decomposed, and further, a colored methylene blue reaction intermediate was decomposed. It was confirmed that

[Example 9]
(Sample preparation)
1.5 L of water was put into a 2 L beaker, and 0.6 g of iron (III) chloride was dissolved to prepare a solution. Next, 5 mL of titanium (IV) chloride was gradually added to the solution, and 90 mL of a sodium carbonate aqueous solution having a concentration of 1 mol / L was gradually added to precipitate titanium hydroxide. Sodium carbonate aqueous solution was added until the pH of the solution reached 10 or more. When titanium (IV) chloride is diluted with water, it emits smoke vigorously and generates heat, and when an aqueous sodium carbonate solution is added, it generates heat. Therefore, this operation was gradually carried out while stirring the solution with ice water in a fume hood.
The produced precipitate was filtered using a suction funnel, pure water was added to the resulting titanium hydroxide precipitate, and the mixture was thoroughly stirred, followed by suction filtration again. This operation was repeated 6 times to remove sodium chloride in the titanium hydroxide precipitate.

  Next, the precipitate was left at 90 ° C. for 10 hours, and water was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a light red-brown colored powder (Sample J).

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L was placed in a glass sample tube, and 30 mg of Sample J colored light reddish brown was added and stirred with a magnetic stirrer to prepare a sample for decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 9.

The result after 18 minutes shows that the performance of the sample J exceeds the performance of the commercial product.
Here, FIG. 9 is a graph obtained by logarithmically plotting the relationship between the irradiation time and the concentration of methylene blue for the sample J and the commercial product. From the slope of the graph, when analyzing the decomposition rate of methylene blue, it was found that the performance of Sample J was higher than that of a commercially available product when the adsorption performance and the decomposition performance were comprehensively judged. The solution after 90 minutes of the light irradiation test turned blue-violet. Furthermore, when 15 mL of methylene blue having an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of sample J was added and irradiated with visible light for 60 minutes while stirring with a magnetic stirrer, methylene blue was completely whitened. It was confirmed that decomposition of the colored methylene blue reaction intermediate occurred.

[Example 10], [Example 11]
(Sample preparation)
1.5 L of water was put into a 2 L beaker, and manganese (II) chloride [Example 10] or chromium (III) chloride [Example 11] was added and dissolved to make a solution. To the solution, 5 mL of titanium (IV) chloride was gradually added. Next, 90 mL of a sodium carbonate aqueous solution having a concentration of 1 mol / L was gradually added to the solution to precipitate titanium hydroxide. Sodium carbonate aqueous solution was added until the pH of the solution reached 10 or more. In addition, when diluting titanium (IV) with water, it generates intense smoke and generates heat. If sodium carbonate aqueous solution is added here, it will generate | occur | produce further. Therefore, the addition operation was gradually performed while cooling the solution with ice water in the draft and stirring the solution. The produced precipitate was filtered using a suction funnel, pure water was added to the resulting titanium hydroxide precipitate, and the mixture was thoroughly stirred, followed by suction filtration again. This operation was repeated 6 times to remove sodium chloride in the titanium hydroxide precipitate.

  Next, the precipitate was left at 90 ° C. for 10 hours, and water was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a light yellow colored powder (Sample K) [Example 10] or a pale blue-green colored (Sample L) [Example 11].

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L is placed in a glass sample tube, and the sample K [Example 10] colored pale yellow or the sample L [Example 11] colored pale blue green is separately sample K. [Example 10] was 20 mg, and sample L [Example 11] was 30 mg. The sample was stirred with a magnetic stirrer to prepare a sample for a decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 10 and Table 11.

As a result after 18 minutes, the performance of the sample K [Example 10] and the sample L [Example 11] exceeds the performance of the commercial product.
Here, FIG. 10 is a graph obtained by logarithmically plotting the relationship between the irradiation time and the concentration of methylene blue for the sample K and the commercially available product, and FIG. 11 shows the irradiation time and the concentration of methylene blue for the sample L and the commercially available product. Is a logarithmic plot of the relationship with. Analysis of the decomposition rate of methylene blue from the slope of the graph shows that the decomposition performance of sample K [Example 10] exceeds that of a commercially available product, and the performance of sample L [Example 11] is the adsorption performance and decomposition performance. Overall, it was found that it was higher than the commercial product. The solution after 90 minutes of the light irradiation test turned blue-violet. Further, 15 mL of methylene blue having an initial concentration of 2 mg / L is placed in a 30 mL glass sample tube, 40 mg of Sample K [Example 10] and Sample L [Example 11] are added, and visible light is stirred for 60 minutes while stirring with a magnetic stirrer. When irradiated, methylene blue was decomposed because it turned completely white, and further, it was confirmed that decomposition of a colored methylene blue reaction intermediate occurred.

[Example 12]
(Sample preparation)
In the same manner as in Example 1, a titanium hydroxide precipitate from which sodium chloride was removed was prepared.
To the obtained titanium hydroxide, 0.08 g of zinc powder was added and mixed well, and the mixture was left at 90 ° C. for 10 hours to completely evaporate water. Sintered at 380 ° C. for 4 hours. The obtained agglomerates were pulverized in a mortar to obtain a gray colored powder (Sample M).

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L was put in a glass sample tube, 30 mg of gray-colored sample M was added, and stirred with a magnetic stirrer to obtain a sample for decomposition experiment. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 12.

As a result after 18 minutes, the performance of the sample M exceeds the performance of the commercial product.
Here, FIG. 12 is a graph in which the relationship between the irradiation time and the concentration of methylene blue is logarithmically plotted for the sample M and a commercial product. From the slope of the graph, when the decomposition rate of methylene blue was analyzed, it was found that the decomposition performance of sample L was higher than that of a commercially available product. The solution after 90 minutes of the light irradiation test turned blue-violet. Furthermore, when 15 mL of methylene blue with an initial concentration of 2 mg / L was placed in a 30 mL glass sample tube, 40 mg of sample M was added and irradiated with visible light for 90 minutes while stirring with a magnetic stirrer, methylene blue was completely whitened. It was confirmed that decomposition of the colored methylene blue reaction intermediate occurred.

[Example 13], [Example 14]
(Sample preparation)
1.5 L of water was put into a 2 L beaker, and 0.06 g of sodium metavanadate [Example 13] or hexaammonium heptamolybdate [Example 14] was added and dissolved to obtain a solution. To the solution, 5 mL of titanium (IV) chloride was gradually added. Next, 90 mL of a sodium carbonate aqueous solution having a concentration of 1 mol / L was gradually added to the solution to precipitate titanium hydroxide. Sodium carbonate aqueous solution was added until the pH of the solution reached 10 or more. In addition, when diluting titanium (IV) with water, it generates intense smoke and generates heat. If sodium carbonate aqueous solution is added here, it will generate | occur | produce further. Therefore, the addition operation was gradually performed while cooling the solution with ice water in the draft and stirring the solution. The produced precipitate was filtered using a suction funnel, pure water was added to the resulting titanium hydroxide precipitate, and the mixture was thoroughly stirred, followed by suction filtration again. This operation was repeated 6 times to remove sodium chloride in the titanium hydroxide precipitate.

  Next, the precipitate was left at 90 ° C. for 10 hours, and water was completely evaporated to obtain a residue. The residue was sintered at 380 ° C. for 4 hours to obtain agglomerates. The obtained agglomerates were pulverized in a mortar to obtain a slightly yellow powder (Sample N) [Example 13] or a slightly yellow color (Sample O) [Example 14].

(Dye solution decomposition experiment)
40 mL of methylene blue having an initial concentration of 5 mg / L is placed in a glass sample tube, and 30 mg of Sample N [Example 13] colored slightly yellow or Sample O [Example 14] colored slightly yellow is separately added. The sample was stirred with a magnetic stirrer to obtain a sample for decomposition experiments. Thereafter, the same experiment as in Example 1 was performed. The experimental results are shown in Table 13 and Table 14.

As a result after 90 minutes, the performance of the sample N [Example 13] and the sample O [Example 14] exceeds the performance of the commercial product.
Here, FIG. 13 is a graph obtained by logarithmically plotting the relationship between the irradiation time and the concentration of methylene blue for the sample N and the commercially available product, and FIG. 14 shows the irradiation time and the concentration of methylene blue for the sample O and the commercially available product. Is a logarithmic plot of the relationship with. When the decomposition rate of methylene blue is analyzed from the slope of the graph and the adsorption performance and the decomposition performance are comprehensively determined, the performance of the sample N [Example 13] exceeds that of a commercially available product, and the sample O [Example 14]. ], It was found that the decomposition performance exceeded that of the commercial product. The solution after 90 minutes of the light irradiation test turned blue-violet. Further, 15 mL of methylene blue having an initial concentration of 2 mg / L is placed in a 30 mL glass sample tube, 40 mg of Sample N [Example 13] and Sample O [Example 14] are added, and visible light is stirred for 60 minutes while stirring with a magnetic stirrer. When irradiated, methylene blue was decomposed because it turned completely white, and further, it was confirmed that decomposition of a colored methylene blue reaction intermediate occurred.

In the example shown here, one kind of element consisting of platinum, silver, copper, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc was dispersed inside and on the surface of the titanium oxide particles. A visible light responsive photocatalyst was shown. Further, according to the study by the present inventors, two or more kinds of combinations consisting of platinum, silver, copper, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc are formed inside and on the surface of the titanium oxide particles. It was found that a visible light responsive photocatalyst can be obtained even when the element is dispersed.

  Further, according to the study by the present inventors, it has been found that the photocatalyst according to the present invention can decompose acetaldehyde with only visible light as a result of an air test.

  Since the photocatalyst according to the present invention exhibits a photocatalytic action only with visible light, it is suitable for environmental improvement such as deodorization, antifouling, sterilization, and decolorization in a space that uses illumination such as an indoor fluorescent lamp that does not contain much ultraviolet rays. Is.

2 is a graph showing the methylene blue decomposition rate of Sample A according to Example 1 and a commercially available product. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample B which concerns on Example 2, and a commercial item. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample C which concerns on Example 3, and a commercial item. It is a graph which shows the methylene blue decomposition rate of the sample D which concerns on Example 4, and a commercial item. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample E which concerns on Example 5, and a commercial item. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample F which concerns on Example 6, and a commercial item. It is a graph which shows the methylene blue decomposition rate of the sample G which concerns on Example 7, and a commercial item. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample H which concerns on Example 8, and a commercial item. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample J which concerns on Example 9, and a commercial item. It is a graph which shows the methylene blue decomposition rate of the sample K which concerns on Example 10, and a commercial item. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample L which concerns on Example 11, and a commercial item. It is a graph which shows the methylene blue decomposition rate of the sample M which concerns on Example 12, and a commercial item. It is a graph which shows the methylene blue decomposition rate of the sample N which concerns on Example 13, and a commercial item. It is a graph which shows the methylene blue decomposition | disassembly rate of the sample O which concerns on Example 14, and a commercial item.

Claims (8)

  At least one element selected from the group consisting of platinum, silver, copper, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc is dispersed inside and on the surface of the titanium oxide particles. A visible light responsive photocatalyst.   The visible light responsive photocatalyst according to claim 1, wherein the element is dispersed as metal fine particles of the element.   The visible light responsive photocatalyst according to claim 1, wherein the element is dispersed as a compound containing the element.   2. The visible light according to claim 1, wherein the element is dispersed as metal fine particles of the element inside the titanium oxide particles, and is dispersed as a compound containing the element on the surface of the titanium oxide particles. Responsive photocatalyst. A first step of hydrolyzing a solution of the titanium compound or adding an alkali to the solution of the titanium compound to precipitate titanium hydroxide; a second step of sintering the titanium hydroxide to obtain titanium oxide particles; Have
At least one selected from the group consisting of copper, platinum, silver, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, molybdenum, and zinc in the first step or between the first and second steps. Add substances containing various elements,
In the second step, a mixture of titanium hydroxide and the compound is sintered, and platinum, silver, copper, nickel, cobalt, iron, manganese, chromium, vanadium, palladium, A method for producing a visible light responsive photocatalyst, wherein at least one element selected from the group consisting of molybdenum and zinc is dispersed.   The method for producing a visible light responsive photocatalyst according to claim 5, wherein titanium chloride, titanium sulfate, titanyl sulfate, and titanium tetraisopropoxide are used as the titanium oxide compound.   The method for producing a visible light responsive photocatalyst according to claim 5, wherein the substance is dispersed as metal fine particles of the element.   The method for producing a visible light responsive photocatalyst according to claim 5, wherein the substance is dispersed as a compound containing the element.

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