JP3338720B2 - Method for producing composite oxide sol - Google Patents

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 a composite oxide sol comprising silica and another inorganic oxide.

[0002]

2. Description of the Related Art Conventionally, composite oxide sols of silica, alumina, zirconia and the like have been known and used as various catalyst raw materials. Each of the composite oxide particles dispersed in these sols is a nonporous particle having almost no pores inside the particle, has a small specific surface area, and generally has an average particle diameter of Dp (nm). When represented by the following expression, the value of the specific surface area S (m ² / g) is less than 3000 / Dp (nm).

[0003] For example, Japanese Patent Publication No. Sho 59-17047 discloses a process for producing an amorphous aluminosilicate sol as a precursor of a catalyst composition. The pH of the solution is strictly controlled to grow the particles to obtain a sol in which non-porous colloidal particles of 3 to 90 nm are dispersed, and then the sol of the non-porous particles is dried to obtain porous agglomerated particles. By constitutively, a powder having a large specific surface area has been successfully obtained.
However, since the colloidal particles of the sol obtained by the above-mentioned production method are non-porous, the use of the composite oxide sol must be limited.

[0004]

The present inventors have previously made an invention relating to a composite oxide sol having a large specific surface area and porous fine particles dispersed therein, and have filed a patent application (Japanese Patent Application No. 4-91650). The invention improves the method for producing the composite oxide sol,
It is an object of the present invention to provide a method for producing a composite oxide sol having a larger specific surface area and in which porous fine particles are dispersed.

[0005]

SUMMARY OF THE INVENTION The method for producing a composite oxide sol of the present invention comprises:
Alkali metal, ammonium or a silicate of an organic base and an alkali-soluble inorganic compound are simultaneously added to an alkaline aqueous solution having a pH of 10 or more to produce colloidal particles composed of silica and an inorganic oxide other than silica, And removing at least a part of elements other than oxygen constituting the inorganic oxide in the colloid particles.

Another method for producing a composite oxide sol according to the present invention is a method for preparing a dispersion of seed particles in which a dispersion of pH 10 or more is prepared by mixing a silicate of an alkali metal, ammonium or an organic base with an alkali-soluble inorganic material. A compound is added at the same time to perform particle growth with the seed particles as nuclei, to generate colloidal particles composed of silica and an inorganic oxide other than silica, and then to form oxygen constituting the inorganic oxide in the colloidal particles. At least a part of the other elements is removed.

[0007]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for producing a composite oxide sol of the present invention will be specifically described. In the present invention, a silicate of an alkali metal, ammonium or an organic base is used as a raw material of silica.

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 salts.
Examples include amines such as quaternary ammonium salts, monoethanolamine, diethanolamine, and triethanolamine. Ammonium silicates and organic base silicates include ammonia, quaternary ammonium hydroxide, amine An alkaline solution containing a compound or the like is also included.

Further, an alkali-soluble inorganic compound is used as a raw material of the inorganic oxide, and a 3A group, 3B group,
Alkali metal salts or alkaline earth metal salts, ammonium salts, and quaternary ammonium salts of a metal or nonmetal oxo acid selected from the group 4A, 4B, 5A, 5B, and 6A, More specifically, sodium aluminate, sodium tetraborate, zirconyl ammonium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, and sodium phosphate are suitable.

The method for producing a composite oxide sol according to the present invention comprises a first step and a second step. In the first step, an alkaline aqueous solution of the compound is separately prepared in advance, or a mixed aqueous solution is prepared in advance, and the aqueous alkaline solution having a pH of 10 or more is prepared according to the composite ratio of the target composite oxide. Add slowly while stirring. The pH value of the solution changes at the same time as the addition of these aqueous solutions. However, in the present invention, no operation for controlling the pH value within a predetermined range is particularly required. The aqueous solution eventually settles to a pH value determined by the type of inorganic oxide and its mixing ratio.

When the pH is controlled within a predetermined range, for example, an acid may be added. In this case, a metal salt as a raw material of the composite oxide is formed by the added acid, and thus the stability of the sol is reduced. May decrease. There is no particular limitation on the rate of addition of the aqueous solution at this time.

The composite oxide sol of the present invention can be produced using a dispersion of seed particles as a starting material. In this case, although there is no particular limitation on the seed particles, SiO 2
₂ , fine particles of an inorganic oxide such as Al ₂ O ₃ , TiO ₂ or ZrO ₂ or fine particles of a composite oxide thereof are used, and usually, these sols can be used. Of course, the sol obtained by the production method of the present invention may be used as a seed particle dispersion.

An aqueous solution of the compound is added to the seed particle dispersion adjusted to pH 10 or higher while stirring, in the same manner as in the above-described method of adding the aqueous solution to the alkaline aqueous solution. Also in this case, the pH control of the dispersion liquid is not performed, but is left to the end. As described above, when the composite oxide particles are grown with the seed particles as nuclei, the particle size of the grown particles can be easily controlled, and particles having a uniform particle size can be obtained.

The above silica raw material and inorganic oxide raw material have high solubility on the alkali side. However, when both are mixed in the pH range where the solubility is large,
The solubility of oxo acid ions such as silicate ions and aluminate ions decreases, and these compounds precipitate and grow into colloidal particles, or precipitate on seed particles to cause particle growth. Therefore, pH control as in the conventional method is not always necessary for the precipitation and growth of colloid particles.

The colloidal particles of the sol obtained in the first step are silica and an inorganic oxide other than silica, specifically, A
l ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ ,
Ce ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , MoO ₃ , WO ₃
Are not mere mixtures with these and the like, but these composite oxides. Further, at this stage, the colloid particles have a larger specific surface area than the colloid particles obtained by the conventional method and are porous.

The mixing ratio of the silica raw material and the inorganic oxide raw material in the first step is preferably such that the molar ratio of silica to the inorganic oxide is in the range of 0.5 to 20. Within this range, the smaller the proportion of silica, the finer the composite oxide fine particles obtained, and the greater the specific surface area. However, when the molar ratio is less than 0.5, the specific surface area of the fine particles hardly increases, and the stability of the sol also deteriorates. On the other hand, when the molar ratio exceeds 20,
The element removal operation in the next second step becomes difficult, and the specific surface area does not increase.

In the second step, at least a part of elements other than silicon and oxygen is selectively removed from the colloid particles composed of the composite oxide. As a specific removal method, an element in the composite oxide is dissolved and removed using a mineral acid or an organic acid, or is removed by contact with a cation exchange resin.

The composite oxide fine particles in the sol obtained by the above method have a large specific surface area and a specific surface area of S (m ² / g),
When the average particle diameter of the fine particles is Dp (nm), the following inequality is satisfied. S (m ² / g) ≧ 3000 / Dp (n
m)

The composite oxide colloid particles obtained by the method of the present invention are particles having a network structure in which silicon and inorganic oxide constituent elements are bonded via oxygen. By removing elements other than silicon and oxygen from such a composite oxide, more porous colloidal particles having a large specific surface area can be obtained. Cannot be maintained. Therefore, the composite ratio (molar ratio) of silica to the final inorganic oxide
Is desirably about 1,000 or less.

When the sol in which the fine particles are dispersed is concentrated, it is preferable to remove a part of the alkali metal ions, alkaline earth metal ions, ammonium ions and the like from the dispersion in advance and then to concentrate the sol. can get. As a removing method, a known method such as ultrafiltration can be adopted.

[0021]

EXAMPLE 1 A mixture of 20 g of silica sol having an average particle diameter 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 the mother liquor contained SiO ₂
G of 1.5% by weight aqueous sodium silicate solution
And 1800 g of a 0.5% by weight aqueous solution of sodium aluminate as Al ₂ O ₃ were added simultaneously. Addition rate is 5
cc / min, during which time the temperature of the reaction was maintained at 80 ° C. Immediately after the addition, the pH of the reaction solution rose to 12.5, and hardly changed thereafter. 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 (first step).

Table 1 shows the pH of the reaction mother liquor, the mixing ratio, the specific surface area and the average particle size of the colloid particles in the first step.
Shown in The specific surface area is determined by the titration method [Analyt
ical Chemistry Vol. 28, No. 12 (1956)], and the average particle diameter was measured by a dynamic light scattering method.

The composite oxide sol obtained in the first step is passed through a cation exchange resin layer to adjust the pH of the sol to 8, and 10 kg of a 0.1% by weight aqueous acetic acid solution is gradually added to 2 kg of the sol. Was added. Next, 6 kg of pure water was added thereto, and the aluminum acetate dissolved therein was separated by an ultrafiltration membrane to obtain a SiO ₂ / Al ₂ O ₃ composite oxide sol of the present invention (second step). Composite ratio of silica to inorganic oxide of colloid particles dispersed in this composite oxide sol SiO ₂ / MO _x
(Molar ratio), specific surface area, product of specific surface area and average particle size (S
× Dp) is shown in Table 2.

Example 2 Instead of the aqueous solution of sodium aluminate of Example 1, B
0.5 wt% aqueous solution of sodium tetraborate as ₂ O ₃ 1
In the same manner as in Example 1 except that 800 g was used, SiO 2 was used.
_{A 2} · B ₂ O ₃ composite oxide sol was obtained (first step). The composite oxide sol was passed through a cation exchange resin layer to adjust the pH of the sol to 2, and 50 liters of a 0.01 N hydrochloric acid aqueous solution was gradually added to 1 kg of the sol. Then, the dissolved boron was removed in the same manner as in Example 1, and the S of the present invention was removed.
An iO ₂ · B ₂ O ₃ composite oxide sol was obtained (second step).

Example 3 Instead of the aqueous solution of sodium aluminate of Example 1, Z
A SiO ₂ / ZrO ₂ composite oxide sol was obtained in the same manner as in Example 1 except that 1800 g of a 0.5% by weight aqueous solution of zirconyl ammonium carbonate was used as rO ₂ (first step). Next, the dissolved zirconium was removed in the same manner as in Example 2 to obtain a SiO ₂ · ZrO ₂ composite oxide sol of the present invention (second step).

Example 4 Instead of the aqueous solution of sodium aluminate of Example 1, S
180% aqueous solution of potassium stannate of 0.5% by weight as nO ₂
In the same manner as in Example 1 except that 0 g was used, SiO _2.
A SnO ₂ composite oxide sol was obtained (first step). Then
The dissolved tin was removed in the same manner as in Example 2 to obtain a SiO ₂ .SnO ₂ composite oxide sol of the present invention (second step).

Example 5 After the same reaction mother liquor as used in Example 1 was heated to 80 ° C., 1200 g of a 2.3% by weight aqueous sodium silicate solution as SiO _{2 and} 0.4 g as Al ₂ O ₃ were added thereto. weight%
G of sodium aluminate aqueous solution and B ₂ O
₃ 1.0 wt% of sodium tetraborate solution 120
0 g simultaneously at an addition rate of 5 cc / min.
_{2 · Al 2 O 3 · B} 2 O 3 to obtain a composite oxide sol (first
Process). Next, the aluminum and tin dissolved in the same manner as in Example 2 were removed, and the SiO ₂ .Al ₂
O ₃ · B ₂ O ₃ composite oxide sol was obtained (second step).

Example 6 In 400 g of a 0.1% by weight aqueous sodium hydroxide solution (pH 12.5) heated to 80 ° C., 0.1% of SiO ₂ was added.
1800 g of a 5% by weight aqueous solution of sodium silicate and Al ₂ O
₃ as a 1.4 wt% aqueous sodium aluminate solution 1
800 g were added at the same time. The addition rate was 5 cc / min, during which the temperature of the reaction was maintained at 80 ° C. The pH of the reaction solution slightly changed and reached 12.4 at the end of the addition. After the addition was completed, the reaction solution was cooled to room temperature, and SiO ₂ was added.
An Al ₂ O ₃ composite oxide sol was obtained (first step).

The composite oxide sol is passed through a cation exchange resin layer to adjust the pH of the sol to 10.5, and then a sodium silicate aqueous solution (SiO 2) obtained by dealkalizing an aqueous sodium silicate solution to 1.5 kg of the sol. ₂ concentration: 2% by weight) 300 g at 80 ° C
Over a period of 6 hours while maintaining the surface treatment of the colloid particles. Next, 30 liters of a 0.01 N hydrochloric acid aqueous solution was gradually added to the sol to remove the aluminum dissolved in the same manner as in Example 2, and the Si of the present invention was removed.
An O ₂ .Al ₂ O ₃ composite oxide sol was obtained (second step).

Example 7 The concentration of the aqueous solution of sodium silicate in Example 6 was 3.0% by weight.
In place, except for changing the concentration of the aqueous sodium aluminate solution to 0.3 wt% in the same manner as in Example 6, SiO ₂ ·
An Al ₂ O ₃ composite oxide sol was obtained (first step). 0.5 kg of a cation exchange resin was added to 2 kg of the composite oxide sol, and the mixture was stirred for 6 hours while maintaining the temperature at 80 ° C. Thereafter, the cation exchange resin was separated by filtration to obtain a dealuminated SiO ₂ · Al ₂ O ₃ composite oxide sol of the present invention (second step).

[0031]

[Table 1] Reaction mixture pH mixing ratio Colloidal particles Early final stage ( molar ratio ) Specific surface area (S ) Average particle size (Dp) Example 1 10.5 12.5 5.1 1100 (m ² / g) 20 (nm) Example 2 10.5 12.1 3.5 1500 15 Example 3 10.5 12.0 6.2 1000 21 Example 4 10.5 12.4 7.5 1050 40 Example 5 10.5 12.3 2.0 1200 18 Example 6 12.5 12.4 0.6 1150 80 Example 7 12.5 12.0 18.0 500 10

[0032]

[Table 2]

[0033]

The method for producing a composite oxide sol according to the present invention does not require strict pH control of the reaction solution.
By performing deelementation by an easy operation, a sol in which the specific surface area of the fine particles is large and the porous composite oxide fine particles are dispersed can be obtained. It has a remarkable effect of being simple.

The sol in which the composite oxide fine particles obtained by the production method of the present invention are dispersed can be applied not only to a use as a catalyst but also to various uses as described below. (1) Since the binder power is large, a high-strength molded article can be obtained when used as a binder for various refractories. For example, when used as a binder for a lost wax method for precision casting, a mold having excellent strength can be obtained. Can be obtained. When 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 cation adsorption capacity, it can be used as an adsorbent for adsorbing and removing ammonium ions and heavy metal ions in wastewater, as a fixing agent for polymer electrolytes, or as a builder incorporated in synthetic detergents. Available. (3) In particular, since it is stable on the high alkali side, it can be used as a cement compounding agent or a soil hardening agent. When used as a soil hardening agent, the gelling rate of the hardening agent is adjusted by the amount of the compounding agent. It becomes possible to do.

(4) Further, 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 colloidal particles. (5) In addition, origami lowering agents, chromatographic fillers, various plastic and rubber fillers, slipperiness improvers, cosmetic compounding agents, lubricants used in the production of sake and beer,
It is useful as a thickener, a food freshness preservative, and the like.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-132309 (JP, A) JP-A-63-123807 (JP, A) JP-A-63-64911 (JP, A) JP-A-1- 317115 (JP, A) JP 50-40119 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01B 33/00-39/54 B01J 13/00 CA (STN) JICST File (JOIS)

Claims (2)

(57) [Claims] 1. An alkali metal, ammonium or organic base silicate and an alkali-soluble inorganic compound,
Simultaneously added to an alkaline aqueous solution of 10 or more to generate colloid particles composed of silica and an inorganic oxide other than silica, and then, 3A group, 3B group, and 3B group of the periodic table constituting the inorganic oxide in the colloid particles . 4A group, 4B group, 5A group,
A method for producing a composite oxide sol, comprising removing at least a part of a metal or a nonmetal element selected from the group 5B and the group 6A . 2. A silicate of an alkali metal, ammonium or an organic base and an alkali-soluble inorganic compound are simultaneously added to a dispersion liquid having a pH of 10 or more in which seed particles are dispersed, and particle growth using the seed particles as a nucleus. To produce colloidal particles composed of silica and an inorganic oxide other than silica, and then 3A, 3B, 4A, 4B, 5A of the periodic table constituting the inorganic oxide in the colloidal particles. Tribe,
A method for producing a composite oxide sol, comprising removing at least a part of a metal or a nonmetal element selected from the group 5B and the group 6A .