JPH05132309A - Compound oxide sol and its production - Google Patents

Abstract

PURPOSE:To obtain a compound oxide sol having high specific surface area of dispersed fine particles and a great number of pores in the interior. CONSTITUTION:A sol comprising dispersed fine particles of a compound oxide composed of silica and an inorganic oxide except silica. An average particle diameter (Dp) and a specific surface area (S) of the fine particles satisfy the inequality S(m<2>/g)>=3,000/Dp (nm). The sol is produced by forming colloidal particles in an aqueous solution of an alkali having pH >=10 or seed particle dispersion having PH >=10 without controlling pH.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite oxide sol composed of silica and other inorganic oxides and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, composite oxide sols of silica and alumina, zirconia, etc. have been known and used as various catalyst raw materials. The composite oxide particles dispersed in these sols are all non-porous particles having almost no pores inside the particles, their specific surface areas are small, and the average particle diameter of the particles is Dp (nm). When expressed, the specific surface area S (m ²
The value of / g) is less than 3000 / Dp (nm).

Further, for example, Japanese Examined Patent Publication No. 59-17047 discloses a method for producing an amorphous aluminosilicate sol as a precursor of a catalyst composition. According to the method described in the publication, heel sol is disclosed. Particle growth is performed by strictly controlling the pH of the solution to obtain a sol in which non-porous colloidal particles of 3 to 90 nm are dispersed, and then the sol of non-porous particles is dried to form porous agglomerated particles. By configuring the above, it has succeeded in obtaining a powder having a large specific surface area.

[0004]

However, since the colloidal particles themselves of the sol obtained by the above-mentioned production method are non-porous, the use of the composite oxide sol must be limited. That is, an object of the present invention is to provide a novel complex oxide sol having a large specific surface area and porous fine particles dispersed therein, and a method for producing the same.

[0005]

SUMMARY OF THE INVENTION The complex oxide sol of the present invention is a sol in which fine particles of a complex oxide consisting of silica and one or more kinds of inorganic oxides other than silica are dispersed. The diameter (Dp) and the specific surface area (S) satisfy the inequality S (m ² / g) ≧ 3000 / Dp (nm). In addition, in the method for producing the composite oxide sol of the present invention, a silicate of an alkali metal, ammonium or an organic base and an alkali-soluble inorganic compound are added at pH 1
It is added at the same time to an alkaline aqueous solution of 0 or more to generate colloidal particles without controlling the pH of the reaction solution.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The composite oxide of the present invention is a composite oxide composed of silica and an inorganic oxide other than silica, and is not a mixture of the respective oxides. As the inorganic oxide, there are 3A group, 3B group, 4A group, 4B group and 5 of the periodic table.
Examples thereof include oxides of metal or non-metal elements of Group A, Group 5B and Group 6A, and specifically, Al ₂ O ₃ and B ₂ O.
₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Ce ₂ O ₃ , P ₂
There are O ₅ , Sb ₂ O ₃ , MoO ₃ , WO _{3 and the} like.

The composite ratio (molar ratio) of silica to the above-mentioned inorganic oxide is suitably in the range of 0.5 to 20. If this ratio exceeds 20, the specific surface area of the fine particles to be described later becomes small, while if it is less than 0.5, the specific surface area of the fine particles hardly increases. Also, the stability of the sol becomes poor.

The present invention is characterized in that the specific surface area S (m ² / g) of the fine particles of the composite oxide dispersed in the sol is large. Specifically, the average particle diameter of the fine particles is Dp (nm). In the case of, the sol is a dispersion of fine particles satisfying the inequality S (m ² / g) ≧ 3000 / Dp (nm).

Next, a method for producing the composite oxide sol will be described. As a raw material of silica, a silicate of alkali metal, ammonium or organic base is used. As the alkali metal silicate, sodium silicate (water glass) or potassium silicate is used. Examples of the organic base include quaternary ammonium salts such as tetraethylammonium salt, amines such as monoethanolamine, diethanolamine and triethanolamine. For the ammonium silicate or the organic base silicate, a silicic acid solution is used. In addition, an alkaline solution obtained by adding ammonia, a quaternary ammonium hydroxide, an amine compound or the like is also included.

As a raw material of the inorganic oxide, an alkali-soluble inorganic compound is used, and the alkali metal salt or alkaline earth metal salt, ammonium salt, or quaternary ammonium salt of the above-mentioned metal or nonmetal oxo acid is used. More specifically, sodium aluminate, sodium tetraborate, zirconyl ammonium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, ammonium cerium nitrate, and sodium phosphate are more suitable. .

In order to produce a complex oxide sol, an alkaline aqueous solution of the above compound is prepared individually or a mixed aqueous solution is prepared in advance, and this aqueous solution is adjusted to a complex ratio of the desired complex oxide. Correspondingly, it is gradually added to the alkaline aqueous solution having a pH of 10 or more while stirring. Although the pH value of the aqueous solution changes at the same time as the addition of these aqueous solutions, the present invention does not particularly require an operation for controlling the pH value within a predetermined range. The aqueous solution finally settles to a pH value determined by the type of inorganic oxide and its composite ratio.
When the pH is controlled within a predetermined range, for example, an acid may be added. In this case, the added acid forms a metal salt as a raw material of the composite oxide, which reduces the stability of the sol. Sometimes. There is no particular limitation on the addition rate of the aqueous solution at this time.

It is also possible to produce the composite oxide sol of the present invention by using a dispersion liquid of seed particles as a starting material. In this case, as seed particles, SiO ₂ , Al
Fine particles of an inorganic oxide such as ₂ O ₃ , TiO ₂ or ZrO ₂ or a composite oxide thereof are used, and normally, a sol of these can be used. Of course, the sol obtained by the production method of the present invention may be used as the seed particle dispersion liquid.

An aqueous solution of the above compound is added to the seed particle dispersion liquid adjusted to pH 10 or above with stirring in the same manner as the above-mentioned method of adding to the alkaline aqueous solution. In this case as well, the pH of the dispersion liquid is not controlled and left as it is. In this way, when the composite oxide particles are grown with the seed particles as the nuclei, it is easy to control the particle size of the grown particles and it is possible to obtain particles having a uniform particle size.

The above-mentioned silica raw material and inorganic oxide raw material have high solubility on the alkaline side. However, if both are mixed in the pH range where the solubility is high,
The solubilities of oxo acid ions such as silicate ions and aluminate ions decrease, and these composites precipitate and grow into colloidal particles, or precipitate on seed particles to cause particle growth. Therefore, when the colloidal particles are deposited and grown, it is not necessary to control pH as in the conventional method. In addition, the colloidal particles of the sol thus obtained have a large specific surface area, unlike the colloidal particles obtained by the conventional method, and are therefore porous.

In the case of concentrating the sol in which the above-mentioned fine particles are dispersed, it is better to remove some of the alkali metal ions, alkaline earth metal ions, ammonium ions and the like in the dispersion liquid in advance and then concentrate the mixture. A stable concentrated sol in which is dispersed is obtained. As a removal method, a known method such as ultrafiltration is adopted.

[0016]

【Example】

Example 1 A mixture of 20 g of silica sol having an average particle size of 5 nm and a SiO ₂ concentration of 20% by weight and 380 g of pure water was heated to 80 ° C. The pH of this reaction mother liquor was 10.5, and 1800 g of 1.5 wt% sodium silicate aqueous solution as SiO ₂ and 1800 g of 0.5 wt% sodium aluminate aqueous solution as Al ₂ O ₃ were simultaneously added to the mother liquor. . The addition rate was 5 ml / min, during which the temperature of the reaction solution was 80
Hold at 0 ° C. Immediately after the addition, the pH of the reaction solution rose to 12.5, and thereafter hardly changed. After the addition was completed, the reaction solution was cooled to room temperature to obtain a SiO ₂ · Al ₂ O ₃ composite oxide sol.

Table 1 shows the specific surface area and average particle diameter of the colloidal particles dispersed in this composite oxide sol. The specific surface area is determined by the titration method [Analytical Chemistry Vol.
8, No. 12 (1956)], and the average particle size was measured by the dynamic light scattering method.

Example 2 The procedure of Example 1 was repeated except that 1800 g of a 0.5 wt% sodium tetraborate aqueous solution as B ₂ O ₃ was used instead of the sodium aluminate aqueous solution of Example 1. _{A 2} · B ₂ O ₃ composite oxide sol was obtained.

[0019] Instead of an aqueous sodium aluminate solution in Example 3 Example 1, except for using as the ZrO ₂ of 0.5 wt% ammonium zirconyl carbonate solution 1800g in the same manner as in Example 1, SiO ₂ · A ZrO ₂ composite oxide sol was obtained.

Example 4 Example 1 was repeated except that 1800 g of a 0.5 wt% potassium stannate aqueous solution as SnO ₂ was used in place of the sodium aluminate aqueous solution of Example 1.
A SiO ₂ · SnO ₂ composite oxide sol was obtained in the same manner as in.

Example 5 The same reaction mother liquor as that used in Example 1 was heated to 80 ° C., and then 1200 g of a 2.3 wt% sodium silicate aqueous solution as SiO ₂ and Al were added.
The ₂ O ₃ as a 0.4 wt% aqueous solution of sodium aluminate 1200g and B ₂ O ₃ as a 1.0 wt.% Of sodium tetraborate aqueous 1200g, and poured simultaneously at an addition rate 5 ml / min, SiO ₂ · Al _{A 2} O ₃ .B ₂ O ₃ composite oxide sol was obtained.

Example 6 400 g of 0.1 wt% sodium hydroxide aqueous solution (pH 12.5) heated to 80 ° C.
Then, 1800 g of a 0.5 wt% sodium silicate aqueous solution as SiO ₂ and 1800 g of a 1.4 wt% sodium aluminate aqueous solution as Al ₂ O ₃ were simultaneously added. The addition rate was 5 ml / min, during which the temperature of the reaction solution was maintained at 80 ° C. The pH of the reaction solution changed slightly and reached 12.4 at the end of the addition. After the addition was completed, the reaction solution was cooled to room temperature to obtain a SiO ₂ · Al ₂ O ₃ composite oxide sol.

[Example 7] Example 6 was repeated except that the concentration of the sodium silicate aqueous solution was changed to 3.0% by weight and the concentration of the sodium aluminate aqueous solution was changed to 0.3% by weight.
In the same manner as described above, a SiO ₂ · Al ₂ O ₃ composite oxide sol was obtained.

Example 8 Tetraethylammonium hydroxide was added to a silicic acid solution (SiO ₂ concentration: 1.5% by weight) obtained by treating an aqueous solution of sodium silicate with a cation exchange resin, and SiO ₂ / (C ₂ H ₅ ) ₄ NOH molar ratio 10
The alkaline aqueous solution added in the ratio of was prepared. Example 1
In the same reaction mother liquor as that used in
00 g and 1800 g of 0.5 wt% sodium aluminate aqueous solution as Al ₂ O ₃ were added at the same time to obtain SiO 2
_{A 2} · Al ₂ O ₃ composite oxide sol was obtained. The conditions at the time of addition are the same as in Example 1.

Example 9 Ammonia was used instead of tetraethylammonium hydroxide, and SiO ₂
S / S in the same manner as in Example 8 except that the NH ₃ molar ratio was changed to 2.
An iO ₂ · Al ₂ O ₃ composite oxide sol was obtained.

[0026]

[Table 1] Reaction solution pH composite ratio Colloidal particles Initial stage (molar ratio) Specific surface area (S ) Average particle size (Dp) S × Dp Example 1 10.5 12.5 5.1 1100 (m ² / g) 20 (nm) 22000 Example 2 10.5 12.1 3.5 1500 15 22500 Example 3 10.5 12.0 6.2 1000 21 21000 Example 4 10.5 12.4 7.5 1050 40 42000 Example 5 10.5 12.3 2.0 1200 18 21600 Example 6 12.5 12.4 0.6 1150 52 59800 Example 7 12.5 12.0 18.0 500 10 5000 Example 8 10.5 12.3 5.1 1200 12 14400 Example 9 10.5 12.1 5.1 950 10 9500

[0027]

INDUSTRIAL APPLICABILITY The complex oxide sol according to the present invention has a large specific surface area of dispersed fine particles and has a large number of fine pores inside the fine particles. Therefore, in addition to the use as a catalyst, it can be applied to various uses such as the following.

(1) Since it has a large binder strength, it can be used as a binder for various refractory materials to obtain a high-strength molded article. For example, if it is used as a binder in the lost wax method for precision casting, it will have high strength. An excellent mold can be obtained. When it is used as a binder for inorganic fibers such as ceramic sheets, inorganic fibers having excellent tensile strength can be obtained. (2) Since it has a large ability to adsorb cations, it can be used as an adsorbent for adsorbing and removing ammonium ions and heavy metal ions in waste water, a fixing agent for polymer electrolytes, or a builder compounded in synthetic detergents.

(3) In particular, since it is stable on the high alkaline side, it can be used also as a cement compounding agent or a soil hardening agent. When it is used as a soil hardening agent, the hardening agent gels depending on the blending amount. It becomes possible to adjust the speed. (4) Furthermore, since it is porous, it can be used as a filler for a low refractive index, or can be used as a coloring material by fixing a dye or pigment in the pores of colloid particles. (5) In addition, a depressant used in the manufacturing process of sake and beer, a chromatographic filler, a filler for various plastics and rubbers, a slipperiness improver, a cosmetic compounding agent, a lubricant,
It is useful as a thickener and a freshness-keeping agent for foods.

The method for producing the complex oxide sol according to the present invention is as follows:
Since it is not necessary to control the pH of the reaction solution, the operation of generating colloidal particles is easy and the manufacturing process can be simplified.

Claims (3)

[Claims] 1. A sol in which fine particles of a composite oxide comprising silica and one or more kinds of inorganic oxides other than silica are dispersed, wherein the average particle diameter (Dp) and the specific surface area (S ) Satisfies the inequality S (m ² / g) ≧ 3000 / Dp (nm). 2. A silicate of an alkali metal, ammonium or an organic base, and an alkali-soluble inorganic compound are mixed in a pH range.
A method for producing a complex oxide sol, which comprises simultaneously adding to 10 or more aqueous alkali solutions to produce colloidal particles without controlling the pH of the reaction solution. 3. The pH of the dispersion liquid is controlled by simultaneously adding an alkali metal, ammonium or organic base silicate and an alkali-soluble inorganic compound to a dispersion liquid of pH 10 or more in which seed particles are dispersed. A method for producing a complex oxide sol, characterized in that the complex oxide particles are grown without using seed particles as nuclei.