JP4033972B2 - Method for producing complex - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a complex, and more particularly to a method for producing a titanium complex capable of stably obtaining titanium dioxide having a high content of anatase type crystal structure.
[0002]
[Prior art]
Conventionally, film-like titanium dioxide (hereinafter sometimes referred to as TiO ₂ ) is often used as an efficient photocatalyst or semiconductor electrode.
Titanium dioxide is also used as an active reagent and an inert carrier. As a method for producing titanium dioxide for such applications, TiO ₂ and V ₂ O ₃ (vanadium oxide) are used as catalysts on the inert carrier. ) And the catalytic oxidation of o-xylene to phthalic anhydride is well known as a commercial process.
Research has also been conducted on the use of titanium dioxide as a fuel by photocatalytically decomposing water to generate hydrogen.
That is, although titanium dioxide has been attracting attention in recent years, titanium dioxide generally contains a lot of rutile type crystal structures and has a problem that the content ratio of anatase type crystal structures is small.
More specifically, for example, in order to effectively exhibit photocatalytic activity, it is preferable that there are many anatase type crystal structures in titanium dioxide, but depending on the type of titanium compound used as the titanium dioxide raw material, anatase type crystals contained There was a problem that the ratio of the structure was easy to change. Therefore, it is difficult to stably contain anatase type crystal structure in titanium dioxide at a high content.
Moreover, when the anatase type crystal structure in titanium dioxide is increased, the hydrophilicity in titanium dioxide can be improved.
[0003]
Therefore, titanium tetrachloride ((NH ₄ ) ₂ (TiO (C ₂ O ₄ ) ₂ ), isopropyl titanate, etc., which have been purified by repeated distillation, have been studied as titanium dioxide raw materials. It did not provide titanium dioxide containing structure.
Specifically, J European Ceramic Society, 1988, 287-297 describes a titanium dioxide powder produced from a precursor obtained by reacting titanium dioxide with triethanolamine and ethylene glycol. However, titanium dioxide obtained from such a precursor contains a rutile crystal structure in the range of 10 to 15% by weight. Therefore, it cannot be said that the content of the anatase crystal structure in titanium dioxide is still high.
[0004]
Further, according to the recently developed sol-gel method, a product made of a titanium compound can be obtained in the form of powder, fiber, film or the like.
Therefore, in producing titanium dioxide, titanium alkoxide such as isopropyl titanate is often used as a starting material in the sol-gel process. According to this sol-gel method, it is said that the stability of the sol of titanium alkoxide can be improved by adding a regulator such as acetylacetonate.
However, even in titanium dioxide obtained using this sol-gel method, it cannot be said that the content of the anatase type crystal structure is sufficiently high.
[0005]
[Problems to be solved by the invention]
That is, an object of the present invention is to provide a method for producing a complex capable of stably obtaining titanium dioxide having a high content (ratio) of anatase type crystal structure.
[0006]
[Means for Solving the Problems]
This invention provides the manufacturing method of the complex characterized by making a titanium amino alcohol complex and a carboxylic anhydride react.
Examples of the titanium amino alcohol complex used in the present invention include a titanium amino alcohol complex having a structure represented by the following general formula (1).
[0007]
General formula (1)
Ti _x [(OR ¹ ) _n N] _x [(OR ¹ ) _x N (R ¹ OH) _y ] (1)
[In General Formula (1), R ¹ represents an alkylene group or an arylene group, x represents a number of 1 to 3, y represents a number of (3-x), and n represents a number of 1 to 3. ]
[0008]
In constituting the titanium amino alcohol complex in the present invention, the alkylene group represented by R ¹ in the general formula (1) is at least one group selected from the group consisting of an ethylene group, a propylene group and a butylene group. It is preferable that These alkylene groups may be linear or branched.
In constituting the titanium amino alcohol complex in the present invention, the arylene group represented by R ¹ in the general formula (1) is at least one selected from the group consisting of a phenylene group, a benzylene group, and a naphthylene group. Preferably there is.
In the present invention, the titanium amino alcohol complex includes those having a part of the structure represented by the above general formula (1).
The titanium amino alcohol complex used in the present invention can be produced, for example, by reacting a titanium compound such as titanic acid, Ti (OR ² ) ₄ , Ti (OCOR ³ ) ₄ with amino alcohol. Here, examples of R ² include hydrogen, an alkyl group, and an aryl group, and examples of R ³ include an alkyl group and an aryl group.
[0009]
Of these titanium compounds, titanic acid is preferred. In the present invention, titanic acid is usually a compound represented by TiO (OH) ₂ · pH ₂ O or Ti (OH) ₄ · pH ₂ O (p represents the number of water and is a number of 1 or more). It is.
Such titanic acid can be produced by adding an alkaline compound such as aqueous ammonia to sulfuric acid titanate or titanium chloride or an aqueous solution thereof.
The amino alcohol used in the present invention is represented by the formula (HOR ¹ ) _n NR ⁴ _m (wherein R ¹ and n are the same as those in the general formula (1), and R ⁴ represents hydrogen, an alkyl group, An aryl group, and m is (3-n).).
Here, preferable amino alcohols include triethanolamine, diethanolamine, monomethanolamine, triisopropanolamine, diisopropanolamine, monoisopropanolamine, methyldiethanolamine, dimethylmonoethanolamine, ethyldiethanolamine, diethylmonoethanolamine and the like. . Moreover, these can be used individually by 1 type or can be used in combination of 2 or more type.
[0010]
The reaction between the titanium compound and amino alcohol is preferably carried out in a solvent. For example, the reaction is preferably carried out in the presence of a monoalcohol, diol or triol alcohol compound.
Here, a preferable monoalcohol includes an alcohol compound represented by R ⁵ OH. R ⁵ is a linear or branched alkyl group having 6 to 10 carbon atoms, or an alkyl group having a linear or branched oxygen bond having 5 to 10 carbon atoms.
Specific examples of the monoalcohol include monoalcohol having a boiling point of 150 ° C. or higher, such as 2-ethylhexanol, 3,3,5-trimethyl-1-hexanol, octanol, and methoxyethoxyethanol.
[0011]
A preferable diol includes an alcohol compound represented by HO (R ⁶ ) OH. Here, R ⁶ is a linear or branched alkylene group having 2 to 12 carbon atoms. Accordingly, preferred specific examples of the diol include one kind of ethylene glycol, propylene glycol, 1,2-butanediol, 1,3-butanediol, hexamethylenediol, or a combination of two or more kinds.
Furthermore, preferable triols for use include glycerin and 1,2,6-hexanetriol.
However, in the reaction between the thian compound and the amino alcohol, the reaction can be further promoted, and therefore, it is also preferable to use an excess amino alcohol as a catalyst or a solvent such as an alkali metal.
[0012]
Further, the reaction ratio between the titanium compound and amino alcohol is not particularly limited, but usually the amino alcohol is within a range of 0.5 to 5 mol, preferably 1 to 3 with respect to 1 mol of the titanium compound. It is to add and react within a molar range, particularly preferably within a range of 1.5 to 2.5 molar.
Further, the reaction temperature between the titanium compound and amino alcohol is not particularly limited, but is usually a value within the range of 90 to 280 ° C, more preferably within the range of 90 to 260 ° C.
The reaction time is related to the reaction temperature, but is preferably in the range of 1 to 40 hours, more preferably in the range of 2 to 10 hours.
Further, the reaction pressure is not particularly limited, but is preferably a value within the range of 0.01 to 1.0 atm, more preferably a value within the range of 0.01 to 0.2 atm. That is.
[0013]
Further, when a solvent is used when the titanium compound and amino alcohol are reacted, the reaction is preferably carried out at or near the boiling point of the solvent. Specifically, the reaction temperature is preferably set to a value within the range of 100 to 280 ° C, more preferably set to a value within the range of 150 to 200 ° C.
For example, when ethylene glycol is used as a solvent, the upper limit of the reaction temperature is about 200 ° C. when the reaction pressure is 1 atm.
Further, when the titanium compound and amino alcohol are reacted, they are preferably mixed in a distillation apparatus substituted with an inert gas such as argon or nitrogen gas. As the inert gas, a known gas other than those described above can be used.
[0014]
In addition, when heating the titanium compound and amino alcohol, it is preferable to continuously remove by-produced water, because the reaction between titanic acid and amino alcohol is promoted.
Moreover, since removal of water which is a by-product from the reaction mixture is promoted by removing the solvent, it is also preferable to gradually remove the solvent from the reaction system.
Moreover, since removal of water is also promoted by carrying out the reaction under reduced pressure, it is preferable to further reduce the atmosphere.
In addition, after completion | finish of reaction with a titanium compound and amino alcohol, the used solvent is removed and a highly purified titanium amino alcohol complex can be obtained by refine | purifying by methods, such as a recrystallization method.
Further, in the present invention, the titanium amino alcohol complex thus obtained is reacted with a carboxylic acid anhydride, whereby a part or all of the amino alcohol-derived structure in the titanium amino alcohol complex is converted into the carboxylic acid anhydride. It can be substituted with the derived structure.
[0015]
In the present invention, carboxylic acid anhydride, preferably acetic anhydride, is usually added to the titanium amino alcohol complex that does not contain a solvent. The carboxylic acid anhydride may be any known one, and examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, and valeric anhydride.
The addition amount of the carboxylic acid anhydride is preferably 0.5 equivalent or more with respect to the titanium atom in the titanium amino alcohol complex. The normal amount used is such that the carboxylic acid anhydride / titanium atomic ratio is in the range of 0.5 to 10,000, preferably in the range of 1 to 5000, and more preferably in the range of 100 to 3000. When the amount of carboxylic anhydride used is small, an inert organic solvent may be used in combination.
The titanium complex obtained by the method of the present invention can be filtered and recrystallized as necessary. The solvent used for recrystallization may be any suitable solvent, but is preferably an organic solvent, particularly methanol, ethanol, or chloroform.
The titanium complex obtained by the method of the present invention can be used as a solution dissolved in water or an organic solvent.
Here, as a preferable solvent, C1-C10 alcoholic solvents, such as water, hexaethylene glycol, isopropylene glycol, methanol, ethanol, can be mentioned. These alcohols may be a mixture with a non-alcoholic solvent such as toluene or chloroform. Also, when using water as a solvent, it is preferably diluted to from 0.06 to 1.6 mol / liter TiO ₂ converted concentration.
The concentration of the titanium complex in the solution is preferably a value in the range of 0.1 to 2.0 mol / liter, more preferably 0.12 to 2.0 mol / liter, in terms of titanium concentration. The value is within the range.
[0016]
In addition, a considerable proportion of non-volatile oligomeric or polymeric amines such as polyethylene glycol and polyvinyl alcohol may be added to the titanium complex solution.
Further, the viscosity of the titanium complex solution is not particularly limited, and can be appropriately changed according to the application.
The titanium complex obtained by the method of the present invention is preferably hydrolyzed by adding water to the solution after adding a solvent to form a solution.
The water used for hydrolysis is added so that the molar ratio of water to Ti contained in the titanium complex (H ₂ O / Ti) is preferably in the range of 2/1 to 200/1. Is more preferable, and a value within the range of 50/1 to 150/1 is more preferable.
[0017]
By making the hydrolyzed titanium complex (solution) alkaline, gelation can easily occur. Specifically, the pH (hydrogen ion concentration) of the hydrolyzed titanium amino alcohol complex (titanium amino alcohol complex solution) is a value within the range of 8-14, preferably a value within the range of 9-11, more preferably. When the value is increased to a value within the range of 9 to 11, most preferably about 10, gelation can be easily caused.
In the present embodiment, the base used for increasing the pH value is preferably general-purpose alkalis such as NH ₃ , (NH ₄ ) ₂ CO ₃ , NaOH, Na ₂ CO ₃ , NH ₄ .HCl, and the like. It is done. The most preferable base for pH adjustment is NH ₃ .
[0018]
Furthermore, when the titanium complex (solution) is heated to 50 ° C. or higher, the gelation rate can be increased. Then, heat the titanium complex (solution), than to the TiO ₂ can be easily formed, it is preferably carried out in the presence of oxygen.
The titanium complex obtained by the method of the present invention can be converted to titanium dioxide by heating.
In the embodiment, the heating temperature of the titanium complex solution or the sol or gel is preferably a value in the range of 500 ° C to 700 ° C, more preferably a value in the range of 600 ° C to 700 ° C, Most preferably, the temperature is about 650 ° C.
More specifically, a titanium complex (solution) or a sol or gel obtained therefrom is coated on a substrate (glass or the like) to form a layer, and then this layer is heated to form a rutile crystal structure. In other words, titanium dioxide (film) having a large amount of anatase type crystal structure can be formed on a substrate.
[0019]
The titanium dioxide thus obtained has a feature that the content of the anatase type crystal structure is usually 60% by weight or more. Further, by adjusting the heating conditions and the like, the content of the anatase type crystal structure can be a value of 80% by weight or more, and can be a value of 95% by weight or more.
In addition, the titanium dioxide thus obtained has a feature that it maintains an anatase type crystal structure even when heated to 650 ° C. or higher for a long period of time and hardly converts to a rutile type crystal structure.
[0020]
Titanium dioxide obtained by heating the titanium complex obtained by the method of the present invention is formed on a substrate such as glass such as soda glass and quartz glass, ceramics such as zirconia and titanium, metal such as iron and stainless steel, etc. Can do.
Further, the method for forming the titanium complex (solution) on the substrate is not particularly limited, but it may be formed and coated by a known method such as a dipping method, a casting method, a roll coating method, or a spin coating method. it can.
Therefore, a substrate obtained by coating a surface of titanium dioxide (film) containing a large amount of anatase type crystal structure obtained from a titanium complex solution is used when a glass is used as an illumination substrate such as an incandescent bulb or a fluorescent lamp. It can be widely used as glass for buildings such as industrial glass, residential glass, and building glass.
[0021]
【Example】
Hereinafter, the present invention will be described in more detail based on examples. Needless to say, the scope of the present invention is not limited to the description of the examples.
[0022]
[Reference Example 1]
30 wt% aqueous ammonia was added in an amount such that the pH was 9 with respect to 25.1 g (0.18 mol) of sulfuric acid titanate (TiOSO ₄ ). Then, an aqueous ammonia solution was further added, and the solution was cooled at a temperature (room temperature) for 16 hours to prepare a titanate sol (TiO (OH) ₂ ).
The obtained titanate sol was repeatedly filtered and washed with purified water several times, and using a saturated barium hydroxide solution, it was confirmed that there was no residual sulfonic acid.
The obtained titanic acid sol had a concentration of 18% by weight in terms of TiO ₂ content and was amorphous.
[0023]
[Example 1]
In the reactor, 40 g of titanate sol obtained in Reference Example 1 (in terms of the amount of TiO ₂ , 0.087 mol) and 19.37 g (0.13 mol) of triethanolamine as amino alcohol were added. As a solvent, 80 ml of ethylene glycol was added to obtain a mixed solution.
Next, this mixed solution was reacted for 3.5 hours under the conditions of a pressure of 6 kPa and a temperature of 120 ° C. using a silicone oil bath. Thereafter, when about half of the ethylene glycol was distilled, it was confirmed that all of the titanic acid in the titanate sol had reacted with triethanolamine because the reaction solution became transparent.
Next, the pressure inside the reactor was reduced to 1.2 kPa, and the temperature was raised to 150 ° C. to remove residual ethylene glycol, whereby a titanium amino alcohol complex was obtained.
2.0 g of the obtained titanium triethanolamine complex was stirred in excess acetic anhydride (10 ml) at room temperature for 2 hours. As the reaction proceeded, a white powder precipitated. The white powder was recrystallized with ethanol, filtered, washed and dried to obtain 0.75 g of chitonalatran acetate (TEA (Ti) OAc). The yield was 79%. Moreover, about the obtained white powder, < ¹³ > C-NMR and < ¹ > H-NMR measurement were performed. The results obtained from each NMR chart are shown below.
NMR (d4MeOD)
¹³ C: 177.7, 74.9, 71.5, 59.3, 57.6, 22.2
¹ H: 4.4-4.5 (m), 4.3 (t), 3.1-3.4 (m), 1.75 (s)
[0024]
[Test example] (Production of titanium dioxide)
Titanium dioxide was prepared by the following steps (1) to (3).
(1) 3 g of the titanium complex obtained in Example 1 was dissolved in 10 ml of absolute ethanol to obtain a solution. While stirring the obtained solution, 10 ml of 50 wt% aqueous ethanol was added dropwise to sol the solution.
(2) Next, 3 ml of 28% by weight ammonia water was dropped while stirring the obtained sol, and further aged at 70 ° C. for 1 hour to gel.
(3) The obtained gel was air-dried for 12 hours, further heated and dried at 80 ° C. for 2 hours, then heated from room temperature to 500 ° C. at a rate of 5 ° C./minute, held at 500 ° C. for 15 minutes, and then from 500 ° C. The temperature was raised to 650 ° C. at 5 ° C./min, and kept at 650 ° C. for 5 minutes to obtain titanium dioxide.
[0025]
The obtained titanium dioxide is irradiated with X-rays having a diffraction angle of 2θ (output condition: 400 kV × 100 mA, CuK wavelength), and the peak intensity (anatase type crystal structure TiO ₂ ) of 2θ = 25.3 to 25.5 is expressed as Ia. And the content intensity (f) of the anatase crystal structure in the obtained titanium dioxide was determined from the following formula, where Ir is the peak intensity of 2θ = 27.5 to 27.9 (rutile-type crystal structure TiO ₂ ). As a result, it was confirmed that the content of the anatase crystal structure was 100%.
f = {1 / (1 + 1.265 × Ir / Ia)} × 100
[0026]
【The invention's effect】
By the method for producing a titanium complex of the present invention, a titanium complex from which titanium dioxide having a high content (ratio) of anatase type crystal structure can be obtained can be produced stably.

Claims (2)

A method for producing a complex, comprising reacting a titanium amino alcohol complex with a carboxylic acid anhydride. The method for producing a complex according to claim 1, wherein the titanium amino alcohol complex is a reaction product of titanic acid and amino alcohol.