CN105948806A - A preparation method of porous stable Bi4Si3O12 bulk material - Google Patents

Abstract

The invention discloses a preparation method of porous steady-state Bi4Si3O12 bulk. The method comprises the following steps: dissolving bismuth oxide in nitric acid, adding an anhydrous ethanol solution of ethyl orthosilicate, preparing sol through reasonably utilizing ethylene diamine tetraacetic acid, citric acid, diethylenetriaminepentacarboxylic acid, tartaric acid, ethylene glycol and polyethylene glycol as dispersants, carrying out water bath treatment, drying the obtained material to prepare xerogel powder suitable for direct compression molding, and carrying out compression molding and heat treatment to obtain the porous steady-state Bi4Si3O12 bulk. The method has the advantages of simple technology device, short period and low cost.

Description

A preparation method of porous stable Bi4Si3O12 bulk material

technical field

The invention belongs to the technical field of materials, and in particular relates to a method for preparing a porous stable Bi ₄ Si ₃ O ₁₂ bulk material.

Background technique

At present, the crystal phases of compounds discovered and studied in the Bi ₂ O ₃ -SiO ₂ system mainly include three types: Bi ₄ Si ₃ O ₁₂ crystals, Bi ₁₂ SiO ₂₀ crystals and Bi ₂ SiO ₅ crystals, among which Bi ₄ Si ₃ O ₁₂ crystal is a kind of stable crystal phase. Currently, methods for preparing Bi ₄ Si ₃ O ₁₂ powder mainly include solid phase method, molten salt method, sol-gel method and hydrothermal method. The porous bulk material not only maintains a high specific surface area by using the fine pores, but also solves the problem of powder material agglomeration by taking advantage of the advantages of the bulk material. To prepare porous bulk materials, the traditional method is to combine the Bi ₄ Si ₃ O ₁₂ powder obtained by the above methods, and then add various substances (such as foaming agents, binders, etc.), and obtain porous bulk materials through molding and heat treatment. The method cycle is long and the process is complicated, which is not conducive to the popularization and application of Bi ₄ Si ₃ O ₁₂ . This patent develops a method for one-step synthesis of porous Bi ₄ Si ₃ O ₁₂ bulk materials.

Contents of the invention

In order to overcome the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing porous and stable Bi ₄ Si ₃ O ₁₂ bulk material, which has the characteristics of simple production process, simple equipment requirements and short cycle time.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for preparing a porous stable state Bi ₄ Si ₃ O ₁₂ bulk material, comprising the steps of:

(1) Dissolving the dispersant in absolute ethanol, adding ethyl orthosilicate and stirring to dissolve to obtain solution A;

(2) dissolving bismuth oxide in nitric acid to form solution B, mixing solution B with solution A, adjusting the pH value to 2-9 to obtain sol B;

(3) Put sol B in a water bath at 80-85°C for 3-5 hours to gel, then dry at 140-160°C to form xerogel, dry it naturally at room temperature, grind and sieve to obtain xerogel powder ;

(4) The sieved dry powder is directly dry-pressed to form a block-shaped green body material, and finally the block-shaped green body material is subjected to heat treatment to obtain a porous stable Bi ₄ Si ₃ O ₁₂ block material.

In the step (1), the dispersant is composed of ethylenediaminetetraacetic acid, citric acid, diethylenetriaminepentacarboxylic acid, tartaric acid, ethylene glycol and polyethylene glycol.

In the solution A, the concentration range of each component of the dispersant is 0-0.5 mol/L.

The amount of tetraethyl orthosilicate and bismuth oxide satisfying that the molar ratio of Bi and Si is (1:1)～(1:4), and the molar ratio of the sum of Si ions and Bi ions to citric acid is 1:( 0.8～1.2).

In the step (4), the heat treatment is to bury the ZnO powder at a temperature of 700°C to 800°C.

Compared with the prior art, the beneficial effect of the present invention is: in the preparation method of the porous stable state Bi ₄ Si ₃ O ₁₂ bulk material provided by the present invention, ethylenediaminetetraacetic acid, citric acid, diethylenetriaminepentacarboxylic acid Acid, tartaric acid, ethylene glycol, polyethylene glycol (such as polyethylene glycol 400, polyethylene glycol 4000, polyethylene glycol 6000), etc. are used as dispersants to directly carry out the gelation process of complex foaming, by controlling The concentration of each substance, especially the amount of each dispersant, the intermediate powder material formed after drying can be directly formed into a block material. In this preparation method, not only the dispersant is used to make bismuth ions and silicon ions evenly exist in the In the system, the crystallization and composite process of the porous stable Bi ₄ Si ₃ O ₁₂ block is more uniform, and the process of granulation and staleness is reduced, and the crystallization process and sintering are completed in one step, which shortens the preparation cycle and reduces the cost. Combined with the heat treatment process of burying and firing, the foaming and decomposition combustion process of organic matter is used to form porous and stable Bi ₄ Si ₃ O ₁₂ blocks, and the porous and stable Bi ₄ Si ₃ O ₁₂ blocks with open pores can be obtained.

detailed description

The implementation of the present invention will be described in detail below in conjunction with the examples.

Example 1

(1) Measure 50mL of absolute ethanol, weigh a certain amount of dispersant (composed of ethylenediaminetetraacetic acid, citric acid, diethylenetriaminepentacarboxylic acid, tartaric acid, ethylene glycol, polyethylene glycol, wherein poly Ethylene glycol (including polyethylene glycol 400, polyethylene glycol 4000 and polyethylene glycol 6000) is added therein, stirred and dissolved, and ethyl tetrasilicate is added therein to form solution A, and the concentration control of each component of the dispersant At 0.5mol/L.

(2) Dissolve bismuth oxide in nitric acid and react to form a solution. The nitric acid is subject to the ability to completely dissolve bismuth oxide, and it is added to solution A, wherein, Bi: Si (molar ratio) = 1: 1, Si ions and Bi ions Sum: citric acid (molar ratio) = 1:0.8. Sol B is obtained by adjusting the pH value to 2-9 with ammonia water (volume concentration 25-28%).

(3) Put sol B in a water bath at 80°C for 3-5 hours until gelatinized, then dry at 140°C to form xerogel, dry naturally at room temperature, grind and sieve the powder.

(4) The sieved dry powder is directly dry-pressed to form a block-shaped green body material, and finally the block-shaped green body material is buried and fired in ZnO powder to obtain a porous and stable Bi ₄ Si ₃ O ₁₂ block material, The heat treatment temperature is 800°C. The obtained porous stable Bi ₄ Si ₃ O ₁₂ bulk material has an open-pore structure, the grain size is about 150nm-500nm, and the gap size is 100nm-300nm.

Example 2

(1) Measure 50mL of absolute ethanol, weigh a certain amount of dispersant (composed of ethylenediaminetetraacetic acid, citric acid, diethylenetriaminepentacarboxylic acid, tartaric acid, ethylene glycol, polyethylene glycol) and add it , stirred and dissolved, and ethyl orthosilicate was added therein to form solution A, and the concentration of each component of the dispersant was controlled at 0.5mol/L.

(2) Dissolve bismuth oxide in nitric acid and react to form a solution. The nitric acid is based on the ability to completely dissolve bismuth oxide, and it is added to solution A, wherein, Bi: Si (molar ratio) = 1:4, Si ions and Bi ions Sum: citric acid (molar ratio) = 1:1.2. Sol B is obtained by adjusting the pH value to 2-9 with ammonia water (volume concentration 25-28%).

(3) Put sol B in a water bath at 80°C for 3-5 hours until gelatinized, then dry at 140°C to form xerogel, dry naturally at room temperature, grind and sieve the powder.

(4) The sieved dry powder is directly dry-pressed to form a block-shaped green body material, and finally the block-shaped green body material is buried and fired in ZnO powder to obtain a porous and stable Bi ₄ Si ₃ O ₁₂ block material, The heat treatment temperature is 700°C. The obtained porous stable Bi ₄ Si ₃ O ₁₂ bulk material has an open-pore structure, the grain size is about 150nm-500nm, and the gap size is 100nm-300nm.

Example 3

(1) Measure 50mL of absolute ethanol, weigh a certain amount of dispersant (composed of ethylenediaminetetraacetic acid, citric acid, diethylenetriaminepentacarboxylic acid, tartaric acid, ethylene glycol, polyethylene glycol) and add it , stirred and dissolved, and ethyl orthosilicate was added therein to form solution A, and the concentration of each component of the dispersant was controlled at 0.01, 0.1, 0.1, 0.5, 0.5, 0.5 mol/L.

(2) Dissolve bismuth oxide in nitric acid and react to form a solution. The nitric acid is subject to the ability to completely dissolve bismuth oxide, and it is added to solution A, wherein, Bi: Si (molar ratio) = 1: 2, Si ions and Bi ions Sum: citric acid (molar ratio) = 1:1. Sol B is obtained by adjusting the pH value to 2-9 with ammonia water (volume concentration 25-28%).

(3) Put sol B in a water bath at 80°C for 3-5 hours until gelatinized, then dry at 150°C to form xerogel, dry naturally at room temperature, and then grind and sieve the powder.

(4) The sieved dry powder is directly dry-pressed to form a block-shaped green body material, and finally the block-shaped green body material is buried and fired in ZnO powder to obtain a porous and stable Bi ₄ Si ₃ O ₁₂ block material, The heat treatment temperature is 700°C. The obtained porous stable Bi ₄ Si ₃ O ₁₂ bulk material has an open-pore structure, the grain size is about 150nm-500nm, and the gap size is 100nm-300nm.

Claims (5)

1. A method for preparing a porous stable state Bi ₄ Si ₃ O ₁₂ bulk material, characterized in that, comprising the steps: (1) Dissolving the dispersant in absolute ethanol, adding ethyl orthosilicate and stirring to dissolve to obtain solution A; (2) dissolving bismuth oxide in nitric acid to form solution B, mixing solution B with solution A, adjusting the pH value to 2-9 to obtain sol B; (3) Put sol B in a water bath at 80-85°C for 3-5 hours to gel, then dry at 140-160°C to form xerogel, dry it naturally at room temperature, grind and sieve to obtain xerogel powder ; (4) The sieved dry powder is directly dry-pressed to form a block-shaped green body material, and finally the block-shaped green body material is subjected to heat treatment to obtain a porous stable Bi ₄ Si ₃ O ₁₂ block material. 2. according to the preparation method of porous stable state Bi ₄ Si ₃ O ₁₂ block material described in claim 1, it is characterized in that, in described step (1), described dispersant is made of ethylenediaminetetraacetic acid, citric acid, two Ethylene triamine pentacarboxylic acid, tartaric acid, ethylene glycol and polyethylene glycol composition. 3. The preparation method of the porous and stable Bi ₄ Si ₃ O ₁₂ block according to claim 2, characterized in that, in the solution A, the concentration range of each component of the dispersant is 0-0.5 mol/L. 4. according to the preparation method of the described porous steady-state Bi ₄ Si ₃ O ₁₂ block material of claim 2, it is characterized in that, the consumption of described ethyl orthosilicate and bismuth oxide satisfies that the mol ratio of Bi and Si is (1: 1)～(1:4), and the molar ratio of the sum of Si ions and Bi ions to citric acid is 1:(0.8～1.2). 5. according to the preparation method of porous stable state Bi ₄ Si ₃ O ₁₂ block material described in claim 1, it is characterized in that, in described step (4), described heat treatment is to carry out buried burning in ZnO powder, and temperature is 700℃～800℃.