JPH04280816A - Production of porous fine particulate titanium oxide - Google Patents

Abstract

PURPOSE:To obtain a fine particulate titanium oxide having active surface free from sintered particles by reacting an aqueous suspension of a specific reaction condensate of hydrated titanium oxide and an organic acid with an alkali metal hydroxide, neutralizing and eliminating the alkali metal. CONSTITUTION:An aqueous solution system at >=50 deg.C, preferably 50-100 deg.C, having dissolved one or more dibasic or tribasic organic carboxylic acids is heated to a fixed temperature. Then, an aqueous solution of titanium tetrachloride is poured to the heated aqueous solution system while stirring, the reaction condensate of hydrated titanium oxide and an organic acid is precipitated, and is filtered, washed with water and dried. Then the reaction condensate is suspended in pure water, reacted with an alkali metal hydroxide at pH>=8 and at >=50 deg.C while stirring and filtered. Then the alkali titanate is suspended again in pure water, mixed with a mineral acid, the alkali metal in the alkali titanate is neutralized at pH <=3 and at >=50 deg.C, eliminated, filtered, washed with water and dried to give the objective porous fine particulate titanium oxide.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing porous titanium oxide fine particles. The porous titanium oxide fine particles obtained by the present invention are useful as raw materials for electronic ceramics, deodorants, cosmetics, paints, inks, and the like.

0002

[Prior Art] Regarding the manufacturing method of titanium oxide fine particles,
So far, many documents and patents have disclosed these manufacturing methods, including methods for directly obtaining titanium oxide fine particles by decomposing titanium tetrachloride using a gas phase method, and titanium sulfate or titanium tetrachloride using a liquid phase method. First, hydrated titanium oxide particles are precipitated by hydrolysis of Although the particle size and specific surface area obtained by these manufacturing methods are typically 0.05 to 0.5 μm, even for what is called ultrafine titanium oxide, the particle size and specific surface area are 350°C calcined. It is 70 m2/g (Japanese Unexamined Patent Publication No. 186418/1983). In addition, since high-temperature calcination is essential for both the gas phase method and the liquid phase method, the particles produced are large and strongly sintered, making it impossible to grind them down to ultra-fine particles with subsequent mechanical grinding. However, it has been difficult to produce active microparticle powders. Also, the manufacturing process was not economical.

0003

[Problems to be Solved by the Invention] The object of the present invention is to produce a surface-active titanium oxide fine particle powder with a large specific surface area that cannot be obtained using conventional techniques (particle size is approximately 0.1 μm or less, and the specific surface area is approximately 150 m2/g or more).

0004

[Means for Solving the Problems] The present inventors have previously developed porous titanium oxide fine particles and a method for producing the same in Japanese Patent Application Laid-Open No.
No. 196029 was disclosed. However, the porous titanium oxide fine particles obtained by this method and the manufacturing method thereof are
Since it requires calcination at 200 to 400°C, it is not economical, and it is also difficult to obtain a titanium oxide fine particle powder with a large specific surface area and an active surface, which is substantially free of sintered particles. The present inventor added an alkali metal hydroxide to an aqueous suspension of a reaction condensate of hydrated titanium oxide and an organic acid disclosed in JP-A-2-196029, and heated the mixture at a temperature of 50°C or higher in an alkaline atmosphere with a pH of 8 or higher. By adding mineral acid and treating at a temperature of 50°C or higher in an acidic atmosphere with a pH of 3 or less, active pores on the surface with a large specific surface area and virtually no sintered particles are formed. The present invention was completed based on the discovery that fine particles of titanium oxide with high quality can be obtained. Furthermore, surprisingly, porous rutile-type titanium oxide is produced when titanium tetrachloride aqueous solution is used as a raw material, and porous anatase-type titanium oxide is produced when titanium tetrachloride aqueous solution containing mineral acid is used as raw material. We obtained completely new knowledge that it is possible to obtain This means that rutile type or anatase type titanium oxide can be produced under the same conditions and operations, differing only in the presence or absence of mineral acid.

That is, the present invention provides a method for dissolving one or more dibasic or tribasic organic carboxylic acids at 50°C.
An aqueous solution of titanium tetrachloride or an aqueous solution of titanium tetrachloride in which a mineral acid has been dissolved is added to the above aqueous solution system, and the resulting reaction condensate of hydrated titanium oxide and an organic acid is filtered and washed with water.
Next, an alkali metal hydroxide was added to the aqueous suspension of the reaction condensate of hydrated titanium oxide and an organic acid, and the pH was adjusted to 8 or higher and 5.
After reacting at a temperature of 0°C or higher, ▲filtration, washing with water, and making an aqueous suspension again, mineral acid was added, and titanic acid was reacted at a temperature of 50°C or higher at pH 3 or lower. This method of producing porous titanium oxide fine particles is characterized by neutralizing and removing the alkali metal, followed by filtration, washing with water, and drying. A specific manufacturing method will be explained below.

The first basis of the present invention is to use one or two dibasic or tribasic organic carboxylic acids such as oxalic acid, malonic acid, succinic acid, malic acid, tartaric acid, citric acid, and gluconic acid. The above prescribed concentration solution (preferably, a total of 0.5 to 5.0 mol of organic acid dissolved in 5 to 20 liters of pure water) is heated to a constant temperature of 50 to 100°C, and while stirring. A solution of titanium tetrachloride at a predetermined concentration (preferably, 0.25 to 2.5 moles of titanium tetrachloride is added to 1.0 to 5 moles of pure water).
0 l) or a solution of titanium tetrachloride at a predetermined concentration in which a mineral acid is dissolved (preferably 0.2 l of titanium tetrachloride).
5 to 2.5 mol and 0.5 to 5.0 mol of hydrochloric acid to 1.0 mol of pure water.
(dissolved in 0 to 5.0 liters) at a constant rate (preferably within 5 hours) to hydrolyze titanium tetrachloride and form a reaction condensate of hydrated titanium oxide and organic acid. It is characterized by filtration and washing with water.

The second basis of the present invention is to suspend the reaction condensate of hydrated titanium oxide and organic acid obtained in the first basis in pure water (preferably, 50 to 200 g of titanium oxide is suspended in pure water .0 to 15.0 l), then suspend this to 50 to 10
A predetermined concentration solution of alkali metal hydroxide (preferably 1.0 to 10.0 mol of alkali metal hydroxide is dissolved in 1.0 to 5.0 liters of pure water while heating to a constant temperature of 0°C and stirring) ) was added to make the suspension pH 8 or higher, and the pH was adjusted to 1.0.
After being treated for ~5.0 hours, it is characterized by ▲filtration and washing with water. Through this operation, the organic acid of the reaction condensate of hydrated titanium oxide and organic acid obtained in the first basic process is neutralized and separated from the reaction condensate, and the alkali metal is hydrated and oxidized in place of the separated organic acid. Combines with titanium to produce alkali titanate.

The third principle of the present invention is to suspend the alkali titanate obtained in the second principle in pure water (preferably, 50 to 200 g of titanium oxide is suspended in 5.0 to 15.0 liters of pure water).
This is heated to a constant temperature of 50 to 100°C, and while stirring, a solution of mineral acid at a predetermined concentration (preferably, 1.0 to 10.0 mol of mineral acid is suspended in 1.0 mol of pure water). ~5.0L) was added to bring the suspension to pH 3 or less, and 1
．． After treatment for 0 to 5.0 hours, it is characterized by ▲filtration, washing with water, and drying. By this operation, the alkali metal of the alkali titanate obtained in the second basic process is neutralized and separated from the alkali titanate, and finally becomes titanium oxide. Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

[0009]

[Examples and Comparative Examples] Example 1 1.5 mol of tartaric acid was dissolved in pure water to make 8.0 liters, and the temperature was raised to 80° C. while stirring. Apart from this, titanium tetrachloride 0
．． Dissolve 8 mol in pure water to make 2.0 liters, and add 5 ml of this to 2.0 liters.
/min. When added to the tartaric acid solution under stirring at an addition rate of , titanium tetrachloride is immediately hydrolyzed to precipitate fine particles of a white reaction condensate of hydrated titanium oxide and tartaric acid. After the addition was completed, the temperature was maintained at 80°C for another 1.0 hour, and then ▲
Filter, wash with pure water until the filtrate reaches pH 5, suspend the wet cake of this reaction condensate in pure water, and adjust to pH 5.0.
1 and raise the temperature to 80°C while stirring. Next, 2.0 mol of sodium hydroxide was dissolved in pure water to make 1.0 l,
The above suspension was added until the pH reached 11, and after maintaining the temperature at 80°C for another 1.5 hours, ▲filtered, and ▲the filtrate had a pH of
The wet cake was washed with pure water until it reached a concentration of 8, and the wet cake was suspended in pure water again to make a total volume of 5.0 liters. The temperature of this suspension was raised to 70°C while stirring, and 2.0 mol of hydrochloric acid was dissolved in pure water.
Add the above suspension until the pH reaches 1.5, maintain the temperature at 70°C for another 1.5 hours, ▲filter, and ▲wash with pure water until the filtrate reaches pH 5. A wet cake is taken out and dried at 80°C to form a good powder that does not require pulverization. When this was confirmed using an electron microscope, it was found to be an aggregate of spherical particles with a diameter of several tens to hundreds of Å, and the size was 0.
．． The specific surface area measured by the BET method was 160 m2/g, which was a very large value. Moreover, rutile type titanium oxide was confirmed by X-ray diffraction analysis.

Comparative Example 1 White granules were obtained under the same conditions and procedures as in Example 1, except that tartaric acid was not used, but the result was very hard dry particles around several mm in size. When this was crushed and confirmed using an electron microscope, it was found to be irregularly shaped particles with a size of several μm to several hundred μm, and could not be called fine particles. Further, the actual value of the specific surface area measured by the BET method was very small, 1.7 mm2/g, and it was confirmed by X-ray diffraction analysis that it was amorphous.

Example 2 A white fine powder was obtained under the same conditions and procedure as in Example 1, except that nitric acid was used instead of hydrochloric acid. When this was confirmed using an electron microscope, it was found to be an aggregate of spherical particles of several tens to hundreds of angstroms, with a size of 0.05 to 0.1 μm.
The actual value of the specific surface area measured by the ET method was 172 m2/g, which was a very large value. Moreover, rutile type titanium oxide was confirmed by X-ray diffraction analysis.

Example 3 2.0 mol of oxalic acid and 1.0 mol of gluconic acid are dissolved in pure water to make 15.0 liters, and the temperature is raised to 100° C. while stirring. Separately, 1.5 mol of titanium tetrachloride was dissolved in pure water to make 5.0 liters, and this was mixed at 25 ml/min. When added to the tartaric acid solution under stirring at an addition rate of , titanium tetrachloride is immediately hydrolyzed to precipitate fine particles of a white reaction condensate of hydrated titanium oxide, oxalic acid, and gluconic acid. After the addition was completed, the temperature was maintained at 100°C for another 1.0 hour, and then ▲filtration▼
▲The filtrate was washed with pure water until the pH reached 5, and the wet cake of this reaction condensate was suspended in pure water to 15.0 liters.
Then, the temperature was raised to 100°C while stirring. Next, 3.0 mol of potassium hydroxide was dissolved in pure water to make 3.0 liters, and added until the pH of the suspension reached 10. After maintaining the temperature at 100°C for an additional 1.0 hour, ▲filtration▲ ▲The pH of the filtrate is
The wet cake was washed with pure water until the size reached 8, and the wet cake was suspended in pure water again to make 10.0 liters. The temperature of this suspension was raised to 100°C while stirring, 4.0 mol of hydrochloric acid was dissolved in pure water to make 2.0 liters, and the suspension was added until the pH reached 1.5, and further 1.0 mol of hydrochloric acid was added until the pH reached 1.5. After maintaining the temperature at 100℃ for an hour, ▲Ro▼
The mixture is filtered, washed with pure water until the filtrate reaches pH 5, taken out as a wet cake, and dried at 80°C to form a good powder that does not require pulverization. When this was confirmed using an electron microscope, it was found to be an aggregate of spherical particles of tens to hundreds of angstroms in size, with a size of 0.01 to 0.1 μm, and the actual value of the specific surface area measured by the BET method was 252 m2/g, which is extremely large. This was a large number. Moreover, rutile type titanium oxide was confirmed by X-ray diffraction analysis.

Example 4 In Example 1, 0.8 mole of titanium tetrachloride and 1.0 mol of hydrochloric acid were used instead of the titanium tetrachloride aqueous solution made by dissolving 0.8 mole of titanium tetrachloride in pure water to make 2.0 liters. Dissolve 2 moles in pure water
．． A white fine powder was obtained under the same conditions and procedure as in Example 1, except that a 0 liter titanium tetrachloride-hydrochloric acid aqueous solution was used. When this was confirmed using an electron microscope, it was found to be an aggregate of spherical particles of tens to hundreds of angstroms, with a size of 0.03 to 0.08 μm, and the actual value of the specific surface area measured by the BET method was 286 m2/
g, which was a very large number. Furthermore, anatase type titanium oxide was confirmed by X-ray diffraction analysis.

Example 5 In Example 3, 1.5 moles of titanium tetrachloride and 4.0 liters of hydrochloric acid were used instead of the titanium tetrachloride aqueous solution made by dissolving 1.5 moles of titanium tetrachloride in pure water to make 5.0 liters. Dissolve 5 moles in pure water
．． A fine white powder was obtained under the same conditions and procedure as in Example 3, except that a titanium tetrachloride-hydrochloric acid aqueous solution of 0 liters was used. When this was confirmed using an electron microscope, it was found to be an aggregate of spherical particles of several tens to hundreds of angstroms in size, with a size of 0.02 to 0.1 μm, and the actual value of the specific surface area measured by the BET method was 245 m2/g.
This was a very large number. Furthermore, anatase type titanium oxide was confirmed by X-ray diffraction analysis.

Comparative Example 2 White granules were obtained under the same conditions and procedures as in Example 5, except that oxalic acid and gluconic acid were not used, but the result was very hard dry particles around several mm in size. When this was crushed and confirmed using an electron microscope, it was found to be irregularly shaped particles with a size of several μm to several hundred μm, and could not be called fine particles. Also, BE
The actual value of the specific surface area measured by the T method was 0.9 m2/g, which was very small, and it was confirmed by X-ray diffraction analysis that it was amorphous.

Example 6 2.0 mol of citric acid, 1.0 mol of malonic acid and 1 mol of oxalic acid
．． 0 mol was dissolved in pure water to make 20.0 liters, and the temperature was raised to 95°C while stirring. Separately, 2.0 moles of titanium tetrachloride and 5.0 moles of hydrochloric acid were dissolved in pure water to make 5.0 liters, and this was mixed at 18 ml/min. When titanium tetrachloride is added to a mixed solution of citric acid, malonic acid, and oxalic acid under stirring at an addition rate of Significant particles of condensate precipitate. After the addition was completed, the temperature was maintained at 95°C for another 2.0 hours, then ▲filtered, ▲washed with pure water until the filtrate reached pH 5, and the wet cake of the reaction condensate was washed with pure water. The solution was suspended in water to make 10.0 liters, and the temperature was raised to 95°C while stirring. Next, 6.0 mol of potassium hydroxide was dissolved in pure water and 3
．． 0l and added until the above suspension reached pH 12,
After maintaining the temperature at 95°C for another 1.0 hour, ▲filtration▼, ▲
The filtrate was washed with pure water until the pH reached 8, and the wet cake was suspended in pure water again to make 10.0 liters. The temperature of this suspension was raised to 95°C while stirring, 8.0 mol of sulfuric acid was dissolved in pure water to make 5.0 liters, and the suspension was added until the pH reached 2.5. After maintaining the temperature at 95℃ for an hour, ▲filtrate, ▲wash with pure water until the filtrate reaches pH 5, take it out as a wet cake, and dry it at 70℃, which is a good product that does not require pulverization. It becomes a fine powder. When this was confirmed using an electron microscope, it was found to be an aggregate of spherical particles of several tens to hundreds of angstroms, with a size of 0.02 to 0.08 μm.
The actual value of the specific surface area measured by the ET method was 277 m2/g, which was a very large value. Furthermore, anatase type titanium oxide was confirmed by X-ray diffraction analysis.

[0017]

[Effect of the invention] The porous titanium oxide fine particles of the present invention are
All of them are ultrafine powders with particle diameters of 0.1 μm or less and are substantially free of sintered particles, and the method of the present invention does not require heat treatment at high temperatures, making it very economical.

[Brief explanation of the drawing]

FIG. 1 is a trace diagram of an electron micrograph showing the shape of porous titanium oxide fine particles obtained in Example 1, and the magnification is 4.
0,000 times.

FIG. 2 is an X-ray diffraction analysis diagram of porous rutile-type titanium oxide fine particles obtained in Example 1.

FIG. 3 is an X-ray diffraction analysis diagram of porous anatase-type titanium oxide fine particles obtained in Example 6.

Claims (2)

[Claims] Claim 1: Hydrated titanium oxide produced by pouring an aqueous solution of titanium tetrachloride into an aqueous solution system at 50°C or higher in which one or more dibasic or tribasic organic carboxylic acids are dissolved. The reaction condensate of an organic acid is filtered and washed with water, and then an alkali metal hydroxide is added to the aqueous suspension of the reaction condensate of hydrated titanium oxide and an organic acid, and the mixture is heated to a pH of 8 or more at 50°C.
After reacting at the above temperature, ▲filtration, washing with water, and making an aqueous suspension again, mineral acid is added, pH is below 3, 5
A method for producing porous titanium fine particles, which comprises neutralizing and removing alkali metals from alkali titanate at a temperature of 0° C. or higher, followed by filtration, washing with water, and drying. 2. The method is characterized in that an aqueous solution of titanium tetrachloride in which a mineral acid is dissolved is poured into an aqueous solution system at 50°C or higher in which one or more dibasic or tribasic organic carboxylic acids are dissolved. The method for producing porous titanium oxide fine particles according to claim 1.