JPH0669888B2 - Hydrothermal Synthesis of Layered Silicate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for hydrothermal synthesis of layered silicate.

[Conventional technology]

Layered silicate is one of the substances expected to be applied to functional materials based on its special structure. This one is
Various applications such as catalysts, fillers, and adsorbents have been developed. In addition, inter-layer modification by intercalation is a field in which development of composite materials including new catalysts and porous materials is progressing.

Currently, the target layered silicates include natural smectite clay minerals and fluorine mica synthesized by the melting method. However, in the future development of functional materials utilizing layered silicates, more efficient synthetic processes using more refined raw materials as starting materials are required.

[Problems to be Solved by the Invention]

The present inventors have paid attention to the reaction between amorphous silica produced by a wet method and an alcohol solution, and as a result of earnest research, it is possible to synthesize layered polysilicate magadiite by using this as a starting material. I found a thing.
Conventionally, it has been known that the synthesis of magadiite requires 100 to 150 ° C, several weeks to several months, or tens of dozen hours at 175 ° C due to the addition of alkali-containing carbonates, but at low temperatures amorphous substances remain and There was a problem that at high temperature, other phases coexist and cannot be obtained as a single phase.

The present invention was made based on the above findings, and an object thereof is to provide a new hydrothermal synthesis method for layered silicates.

[Means for Solving the Problems]

That is, according to the present invention, a liquid source comprising a silica source, an alkali metal source, water and alcohol, and 0.1 to 0.3 mol of alkali metal and 10 to 30 mol of water per 150 mol of SiO _{2 is} added to a liquid having a temperature of 150 ° C. or higher. A hydrothermal synthesis method of a layered silicate is provided which is characterized by reacting under thermal conditions.

Amorphous silica is preferably used as the silica source used in the present invention. In general, silica synthesized by a wet method may be used, and its history is not particularly limited. For example, silica obtained using sodium silicate or alkoxide as a raw material and amorphous silica obtained by treating silicate ore with a mineral acid can be used. Also, sodium silicate itself can be used as the silica source. When using a solid one as a silica source, the particle size is not particularly limited, but if it is too large it is not preferable because it takes a long time to completely dissolve and react, and it is generally preferable to use a powder smaller than 100 mesh. .

It is preferable to use sodium hydroxide or potassium hydroxide as the alkali metal source. Further, sodium silicate can be used as both a silica source and an alkali metal source.

As the alcohol, an aliphatic alcohol having 2 to 6 carbon atoms is generally used, and a linear alcohol having 3 to 5 carbon atoms is preferably used. With increasing alkalinity, the use of alcohols with higher carbon numbers is preferred. For example, use of n-butanol is preferred when the molar ratio of alkali metal to silica is about 0.2, while use of 1-pentanol is preferred when the molar ratio is about 0.25.

The ratio of components in the raw material mixture is 0.1 to 0.3 mol of alkali metal and 10 to 30 mol of water with respect to 1 mol of silica. The amount of alcohol used is 0.2 to 1 mol of silica.
The amount is 3.0 mol, preferably 1.0 to 2.0 mol.

In addition, the raw material mixture, if necessary, as an auxiliary component,
Alumina sources such as sodium aluminate, aluminum sulfate, and alumina, magnesium hydroxide, and magnesia sources such as magnesia are used in appropriate amounts (for example, 1 mol of silica)
0.04 to 0.8 mol) can also be added.

When the reaction temperature is low, it takes a long time to react, and when the reaction temperature is high, it may be necessary to suppress crystallization of other substances. Therefore, a temperature of 150 ° C. or higher, particularly about 170 ° C. is preferable. The stirring is sufficient if the uniformity of the entire system can be maintained. The reaction pressure is 1 to 1 in total pressure.
The pressure is 20 atm, preferably 7 to 9 atm.

The solid substance synthesized under the above conditions is separated from the mother liquor by a conventional method, and then washed with an alkaline solution of about 10 ^-3 to 10 ^-4 mol / l (alkali metal solution of the same kind as the mother liquor) or washed with water. After that, it is dried and collected.

[Action]

In the synthesis method of the present invention, a layered silica tetrahedron is formed by the crystallization effect due to the solubility reduction based on the alcohol addition of the silica component dissolved in an alkaline solution and the conformational regulation effect of the silica polyhedron, and the alkali metal It is believed that the combination forms a crystalline layered silicate.

In order to form a silicate skeleton having a layered structure,
N-Butanol having an alkyl group having 4 carbon atoms is the most effective, and the same effect is confirmed with n-butylamine. Therefore, the conformational regulation by the linear C ₄ H ₉ group forms a layered structure. It seems that it will greatly contribute to. But,
The higher the alkalinity, the higher the solubility of the silica content. Therefore, in order to enhance the crystallization effect without destroying the layered structure, it is effective to use an alcohol having a higher alkyl chain carbon number.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

Example 1 SiO ₂ content generated by dissolution of serpentine in sulfuric acid was 99.7% or more (however, it was converted by excluding water contained therein, and thereafter, chemical analysis values were based on this) and had a particle size of 100 to 200 mesh. 25 g of amorphous silica 0.5N sodium hydroxide solution
It was added to a mixed solution of 150 cc and 50 cc of a commercial grade butanol solution, and the mixture was reacted in an autoclave at 170 ° C. for 24 hours.

After completion of the treatment, the liquid phase was separated by filtration and washed with a 10 ^-4 mol / l sodium hydroxide solution. When the collected solid was dried at 40 ° C. and then measured by X-ray diffractometry, only magadiite was found to be produced. No change was observed in the X-ray diffraction pattern even after washing with water, and this was the same in the following examples.

Example 2 SiO ₂ generated by dissolving sulfuric acid in serpentine ₂ min 99.7% or more and grain size 28
25 g of 0-mesh or less amorphous silica 0.5 cc sodium hydroxide solution 150 cc and commercial grade butanol solution 50 cc
Was added to the mixed solution of and the reaction was carried out in an autoclave at 170 ° C. for 12 hours.

After completion of the treatment, the liquid phase was separated by filtration and washed with a 10 ^-4 mol / l sodium hydroxide solution. When the collected solid was dried at 40 ° C. and then measured by X-ray diffractometry, only magadiite was found to be produced.

Example 3 SiO ₂ produced by dissolution of serpentinite in sulfuric acid ₂ min 99.7% or more and particle size 28
25 g of 0-mesh or less amorphous silica 0.7 cc sodium hydroxide solution 150 cc and commercial grade pentanol solution 50 c
It was added to the mixed solution of c and reacted in an autoclave at 170 ° C. for 12 hours.

After completion of the treatment, the liquid phase was separated by filtration and washed with a 10 ^-4 mol / l sodium hydroxide solution. When the collected solid was dried at 40 ° C. and then measured by X-ray diffractometry, only magadiite was found to be produced.

Example 4 SiO ₂ produced by dissolution of serpentinite in sulfuric acid ₂ min 99.7% or more and particle size 28
25 g of 0-mesh or less amorphous silica 150 cc of 0.35N sodium hydroxide solution and 50 cc of commercial grade butanol solution
Was added to the mixed solution of and the reaction was carried out in an autoclave at 170 ° C. for 24 hours.

After completion of the treatment, the liquid phase was separated by filtration and washed with a 10 ^-4 mol / l sodium hydroxide solution. When the collected solid was dried at 40 ° C. and measured by an X-ray diffraction method, coexistence of an amorphous substance was recognized, but only magadiite was generated.

Example 5 SiO ₂ generated by dissolution of serpentinite in sulfuric acid ₂ minutes 99.7% or more and particle size 10
25 g of 0-mesh or less amorphous silica was added to a mixture of 150 cc of 0.5 N sodium hydroxide solution and 50 cc of commercial grade ethanol, or propanol or pentanol solution, and reacted in an autoclave at 170 ° C for 12 to 24 hours.

After completion of the treatment, the liquid phase was separated by filtration and washed with a 10 ^-4 mol / l sodium hydroxide solution. When the collected solid was dried at 40 ° C. and measured by an X-ray diffraction method, coexistence of an amorphous substance was recognized, but only magadiite was generated.

〔The invention's effect〕

Since magadiite has a micropore based on its peculiar layered structure, it can be expected to be used in many fields such as chemical industry, ceramic industry, and medicine. For example, a catalyst carrier,
It is considered to be applicable to packing materials, adsorbents, deodorants, enzyme sensors, microbial separation, etc. In addition, it can be expected to be useful as a layered compound when producing a new catalyst, a porous material or the like by intercalation reaction, a microbial release agent, a pharmacologically active substance, or pillar formation between layers.

Further, the crystalline layered polysilicic acid obtained by treating this with an acid is composed of only a silica content, and for applications in which amorphous silica has been used, for example, catalysts, catalyst carriers, fillers, adsorbents, deodorants, etc., It is possible to impart high performance, and it is expected that it will be useful as a layered compound for the creation of various functional materials including composite materials by the intercalation reaction utilizing a special structure as described above.

Claims (3)

[Claims] 1. A silica source, an alkali metal source, water and an alcohol, and 0.1 to 0.3 alkali metal per mole of SiO _2.
A hydrothermal synthesis method for a layered silicate, which comprises reacting a liquid mixture containing 10 to 30 mol of water and 150 to 30 mol of water under hydrothermal conditions of 150 ° C or higher. 2. The method according to claim 1, wherein amorphous silica is used as the silica source. 3. The method of claim 1 or 2 wherein said liquid mixture contains an alumina source or a magnesia source.