Preparation method of spherical porous silicon dioxide

Abstract

The invention belongs to the technical field of silicon dioxide preparation, and relates to a preparation method of spherical porous silicon dioxide, which comprises the following steps: S1, preparing a mixed solution, namely preparing a template solution, namely dissolving 0.5 g of hexadecyl trimethyl ammonium bromide into 100ml of deionized water mixed solution, and stirring by using a stirring mechanism until the solution is clear; adjusting the alkaline environment: adding 1ml of ammonia water, and adjusting the pH value to 10-11; s2, silicon source hydrolysis: slowly dropwise adding 2ml of tetraethyl orthosilicate into the solution in the step S1, and then carrying out stirring reaction; s3, aging and centrifugal washing: aging: stopping stirring, and standing for 12 hours to stabilize the structure; centrifugal washing: centrifuging for 5 minutes at 8000rpm, and sequentially washing for 3 times by using ethanol and water to remove unreacted substances; the spherical silicon dioxide can be protected by a simple sol-gel method without using a complex auxiliary agent, the mesoporous size of the spherical silicon dioxide is relatively uniform, the supercritical carbon dioxide is adopted for drying in a drying box, the pore structure is kept complete, and the use effect is improved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon dioxide preparation, and more specifically to a method for preparing spherical porous silicon dioxide. Background Art

[0002] The causes of air pollution include nitrogen oxides, volatile organic compounds, etc., and their main sources include automobile exhaust, industrial emissions, etc.; the emission control of gaseous pollutants is an important part of the current environmental pollution control field; in order to control and reduce the emission of pollutants and achieve the goal of reducing the emission of pollutants such as volatile organic compounds and NOx, higher requirements are put forward for the research and development and promotion of existing technologies; among various control technologies, adsorption method is widely used due to its simplicity and ease, and the core of it is the selection of adsorbents. For different pollutants, the selection of specific adsorbents is the key to the control effect of this technology; Generally, porous silica is amorphous, and after being treated at a high temperature, a certain amount of skeleton shrinkage will occur, which will reduce its specific surface area and adsorption performance. However, porous silica materials with good crystalline structure have uniform pore structure and high thermal stability, and have attracted attention in the field of selective adsorption and catalysis. The synthesis of such porous silica materials is generally carried out by water (alcohol) thermal method, which needs to be completed under high temperature and high pressure conditions, and has high requirements for synthesis equipment and synthesis conditions. At present, in the preparation process of porous spherical silica materials, the spherical silica is dried and then calcined. The ordinary drying method is used during the drying process, but it is difficult to maintain the integrity of the silica pore structure, which affects the use effect. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a method for preparing spherical porous silica.

[0004] A method for preparing spherical porous silica. S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 10-11; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react; S3, aging and centrifugal washing (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven; (2) Calcination: After drying, the product is placed in a calcination furnace for calcination to decompose hexadecyltrimethylammonium bromide to form porous silica.

[0005] Preferably, in step S1, the pH value of the mixed solution is adjusted to 10 with aqueous ammonia; Preferably, in step S1, the pH value of the mixed solution is adjusted to 11 with aqueous ammonia.

[0006] Preferably, in step S2, the stirring speed is 500 rpm and the reaction time at room temperature is 6 hours.

[0007] Preferably, in step S2, tetraethyl orthosilicate is hydrolyzed under alkaline regulation to generate silicic acid, which is condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles are used as a template to guide the formation of mesopores.

[0008] Preferably, in step S4, supercritical carbon dioxide is used for drying in a drying oven to keep the pore structure intact.

[0009] Preferably, in step S4, the drying temperature in the drying oven is 60 degrees and the drying time is 12 hours.

[0010] Preferably, in step S4, the calcination temperature is 550°C for 4 hours (heating rate 2°C / min).

[0011] In summary, the present invention includes at least one of the following beneficial technical effects: The present invention uses a simple sol-gel method to form spherical silicon dioxide for protection without using complex additives, and the mesopore size of the spherical silicon dioxide is relatively uniform. It is dried in a drying oven using supercritical carbon dioxide to keep the pore structure intact and improve the use effect. DETAILED DESCRIPTION

[0012] The present invention is described in further detail.

[0013] Example 1 A method for preparing spherical porous silica. S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 10; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react, the stirring speed is 500 rpm, the reaction time at room temperature is 4 hours, tetraethyl orthosilicate is hydrolyzed to generate silicic acid under alkaline regulation, condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles are used as templates to guide the formation of mesopores; S3, aging and centrifugation (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven. Using supercritical carbon dioxide in a drying oven can keep the pore structure intact. (2) Calcination: After drying, the product is placed in a calcination furnace for calcination at a temperature of 550°C for 4 hours (heating rate of 2°C / min) to decompose hexadecyltrimethylammonium bromide to form porous silica.

[0014] Example 2 S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 10; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react, the stirring speed is 500 rpm, the reaction time at room temperature is 6 hours, tetraethyl orthosilicate is hydrolyzed to generate silicic acid under alkaline regulation, condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles are used as templates to guide the formation of mesopores; S3, aging and centrifugal washing (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven. Using supercritical carbon dioxide in a drying oven can keep the pore structure intact. (2) Calcination: After drying, the product is placed in a calcination furnace for calcination at a temperature of 550°C for 4 hours (heating rate of 2°C / min) to decompose hexadecyltrimethylammonium bromide to form porous silica.

[0015] Example 3 S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 10; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react, the stirring speed is 500 rpm, the reaction time at room temperature is 8 hours, tetraethyl orthosilicate is hydrolyzed to generate silicic acid under alkaline regulation, condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles are used as templates to guide the formation of mesopores; S3, aging and centrifugal washing (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven. Using supercritical carbon dioxide in a drying oven can keep the pore structure intact. (2) Calcination: After drying, the product is placed in a calcination furnace for calcination at a temperature of 550°C for 4 hours (heating rate of 2°C / min) to decompose hexadecyltrimethylammonium bromide to form porous silica.

[0016] Example 4 S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 11; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react, the stirring speed is 500 rpm, the reaction time at room temperature is 4 hours, tetraethyl orthosilicate is hydrolyzed to generate silicic acid under alkaline regulation, condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles are used as templates to guide the formation of mesopores; S3, aging and centrifugal washing (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven. Using supercritical carbon dioxide in a drying oven can keep the pore structure intact. (2) Calcination: After drying, the product is placed in a calcination furnace for calcination at a temperature of 550°C for 4 hours (heating rate of 2°C / min) to decompose hexadecyltrimethylammonium bromide to form porous silica.

[0017] Example 5 S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 11; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react, the stirring speed is 500 rpm, the reaction time at room temperature is 6 hours, tetraethyl orthosilicate is hydrolyzed to generate silicic acid under alkaline regulation, condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles are used as templates to guide the formation of mesopores; S3, aging and centrifugal washing (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven. Using supercritical carbon dioxide in a drying oven can keep the pore structure intact. (2) Calcination: After drying, the product is placed in a calcination furnace for calcination at a temperature of 550°C for 4 hours (heating rate of 2°C / min) to decompose hexadecyltrimethylammonium bromide to form porous silica.

[0018] Example 6 S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 10; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react, the stirring speed is 500 rpm, the reaction time at room temperature is 8 hours, tetraethyl orthosilicate is hydrolyzed to generate silicic acid under alkaline regulation, condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles are used as templates to guide the formation of mesopores; S3, aging and centrifugal washing (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven. Using supercritical carbon dioxide in a drying oven can keep the pore structure intact. (2) Calcination: After drying, the product is placed in a calcination furnace for calcination at a temperature of 550°C for 4 hours (heating rate of 2°C / min) to decompose hexadecyltrimethylammonium bromide to form porous silica.

[0019] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made according to the principles, components, ratios, and methods of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing spherical porous silica, characterized in that: The steps are as follows: S1. Preparation of mixed solution (1) Template solution: Dissolve 0.5 g of hexadecyltrimethylammonium bromide in 100 ml of deionized water and stir until the solution becomes clear. (2) Adjust the alkaline environment: add 1 ml of ammonia water and adjust the pH to 10-11; S2, hydrolysis of silicon source: slowly drop 2 ml of tetraethyl orthosilicate into the solution in step S1, and then stir to react; S3, aging and centrifugal washing (1) Aging: Stop stirring and let stand for 12 hours to stabilize the structure; (2) Centrifugal washing: centrifuge at 8000 rpm for 5 minutes, wash with ethanol and water three times in sequence to remove unreacted products; S4. Drying and calcination (1) Drying: Drying in a drying oven; (2) Calcination: After drying, the product is placed in a calcination furnace for calcination to decompose hexadecyltrimethylammonium bromide to form porous silica.

2. The method for preparing spherical porous silica according to claim 1, characterized in that: In step S1, the pH value of the mixed solution is adjusted to 10 with aqueous ammonia.

3. The method for preparing spherical porous silica according to claim 1, characterized in that: In step S1, the pH value of the mixed solution is adjusted to 11 with aqueous ammonia.

4. The method for preparing spherical porous silica according to claim 1, characterized in that: In step S2, the stirring speed is 500 rpm and the reaction time at room temperature is 6 hours.

5. The method for preparing spherical porous silica according to claim 1, characterized in that: In step S2, tetraethyl orthosilicate is hydrolyzed under alkaline regulation to generate silicic acid, which is condensed to form a silica network, and hexadecyltrimethylammonium bromide micelles serve as a template to guide the formation of mesopores.

6. The method for preparing spherical porous silica according to claim 1, characterized in that: In step S4, supercritical carbon dioxide is used for drying in a drying oven to keep the pore structure intact.

7. The method for preparing spherical porous silica according to claim 1, characterized in that: In step S4, the drying temperature in the drying oven is 60 degrees and the drying time is 12 hours.

8. The method for preparing spherical porous silica according to claim 1, characterized in that: In step S4 , the calcination temperature is 550° C. for 4 hours (heating rate 2° C. / min).