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CN-118908180-B - Preparation process of mesoporous carbon

CN118908180BCN 118908180 BCN118908180 BCN 118908180BCN-118908180-B

Abstract

The invention discloses a preparation process of mesoporous carbon with a recyclable silicon source and mesoporous carbon with small aperture and large specific surface area. The preparation process of the mesoporous carbon comprises the steps of preparing a silicon template, reacting a fluosilicic acid solution with calcium carbonate, separating calcium fluoride precipitate and silica sol, wherein the pH value of the silica sol is 2-5, the concentration of silicon dioxide in the silica sol is 1-8wt%, preparing a precursor, dissolving a carbon source and an organic acid in the silica sol, drying, grinding and carbonizing in an inert atmosphere to obtain a C/Si precursor, wherein the organic acid comprises at least one of oxalic acid, tannic acid, acetic acid and citric acid, removing the silicon template and recovering the silicon source, treating the C/Si precursor with hydrofluoric acid, and separating solid from liquid to obtain the mesoporous carbon and the fluosilicic acid solution, wherein the fluosilicic acid solution is used for preparing the silicon template. The specific surface area of the mesoporous carbon is more than 800m 2 /g, and the pore diameter is less than 6nm.

Inventors

  • LI YING
  • WANG MINGYUAN
  • Cheng Zaizhe
  • LAN GUOJUN
  • XIE HUIMIN
  • QIU YIYANG
  • SUN XIUCHENG
  • CHEN YI

Assignees

  • 浙江工业大学
  • 湖州佳炭新材料科技有限公司

Dates

Publication Date
20260508
Application Date
20240719

Claims (10)

  1. 1. A process for preparing mesoporous carbon with a recyclable silicon source, comprising: preparing a silicon template, namely reacting fluosilicic acid solution with calcium carbonate, and separating calcium fluoride precipitate and silica sol, wherein the pH value of the silica sol is 2-5, and the concentration of silicon dioxide in the silica sol is 1-8wt%; Preparing a precursor, namely dissolving a carbon source and an organic acid in silica sol, and drying, grinding and carbonizing in an inert atmosphere to obtain a C/Si precursor, wherein the organic acid comprises at least one of oxalic acid, tannic acid, acetic acid and citric acid; and (3) removing the silicon template and recovering a silicon source, namely treating the C/Si precursor with hydrofluoric acid, and carrying out solid-liquid separation to obtain mesoporous carbon and fluosilicic acid solution, wherein the fluosilicic acid solution is used for preparing the silicon template.
  2. 2. The process for preparing mesoporous carbon according to claim 1, further comprising reacting said calcium fluoride precipitate with sulfuric acid to form hydrofluoric acid for treating said C/Si precursor.
  3. 3. The process according to claim 1, wherein the fluorosilicic acid solution used in the process is a byproduct of chemical fertilizer industry and/or a fluorosilicic acid waste liquid obtained by treating C/Si precursor with hydrofluoric acid is recycled.
  4. 4. The mesoporous carbon preparation process according to claim 1, wherein in the process of preparing the silicon template, the mass ratio of calcium carbonate to water in a reaction system is 1:2-7, the calcium carbonate is just enough or excessive relative to fluosilicic acid, and the molar ratio of fluosilicic acid to calcium carbonate is 1:3-5.
  5. 5. The process for preparing mesoporous carbon according to claim 1, wherein said carbon source comprises at least one of glucose, sucrose, lactose, maltose, glycine, humic acid, and soluble starch.
  6. 6. The process for preparing mesoporous carbon according to claim 1, wherein in the process of preparing the precursor, the mass ratio of the carbon source to the silica in the silica sol is 2-9:1.
  7. 7. The process for preparing mesoporous carbon according to claim 1, wherein in the process of preparing the precursor, the molar ratio of the organic acid to the silica in the silica sol is 0.01-0.5:1.
  8. 8. The process for preparing mesoporous carbon according to claim 1, wherein said inert atmosphere is a nitrogen atmosphere; the carbonization temperature is 700-850 ℃ and the carbonization time is 1-2 h.
  9. 9. The process for preparing mesoporous carbon according to claim 1, wherein, in the treatment of the C/Si precursor with hydrofluoric acid: the molar ratio of hydrofluoric acid to silicon dioxide in the C/Si precursor is 5.5-8:1; The treatment time is 12-24 hours; In the process of treating the C/Si precursor by using hydrofluoric acid, the C/Si precursor is treated by using hydrofluoric acid in a form of hydrofluoric acid aqueous solution, wherein the mass fraction of the hydrofluoric acid in the hydrofluoric acid aqueous solution is 8% -15%.
  10. 10. The process for preparing mesoporous carbon according to any one of claims 1 to 9, wherein the specific surface area of the mesoporous carbon is more than 800 m 2 /g and the pore diameter is less than 6 nm.

Description

Preparation process of mesoporous carbon Technical Field The invention relates to the technical field of mesoporous carbon preparation, in particular to a preparation process of mesoporous carbon with a recyclable silicon source and mesoporous carbon with small aperture and large specific surface area. Background The mesoporous carbon has wide application potential in the fields of catalyst carriers, adsorption, hydrogen storage, electrode materials, environment, medicine and the like, and has high specific surface area, strong adsorption capacity, good conductivity, stable chemical property and adjustable surface chemical property. At present, the preparation process of the mesoporous carbon is mostly a template method and is divided into a hard template method and a soft template method. The template method has the advantages that the prepared mesoporous carbon has high specific surface area, uniform pore diameter and regular arrangement, the pore diameter of the mesoporous carbon is limited by the wall thickness of the template, the requirements of special industries such as electrochemical electrode materials (pore diameter is required to be less than 6 nm) are difficult to reach, and a large amount of waste acid and alkali lye is generated in the template removing process. Therefore, a preparation process for preparing the mesoporous carbon material with high specific surface area and uniform pore diameter is needed to be found out by starting with cheap raw materials, reasonably solving the problems of waste acid and waste alkali. The patent specification with the application number of CN202010572464.5 discloses a process for preparing high-purity fluorite by quickly reacting fluosilicic acid with calcium carbonate, wherein the technology of the patent utilizes the reaction of fluosilicic acid and calcium carbonate, forms calcium fluoride under the room temperature condition through a protective agent, and obtains high-purity fluorite powder through the separation of silicon dioxide and the calcium fluoride. The technology of this patent is not concerned with the treatment of silica. Patent specification with the application number of CN201711329074.X discloses a preparation method of a mesoporous carbon catalyst, wherein phenol-aldehyde is used as a carbon precursor, commercial silica sol is used as a hard template agent, a carbon/silicon composite material is prepared through sol-gel, drying and carbonization, then alkali liquor treatment is used for synchronously carrying out etching and loading, and finally drying is carried out to obtain the alkaline mesoporous carbon catalyst. The method realizes simplification of the preparation and loading processes of the mesoporous carbon, but the method still forms alkali waste liquid, and the pore diameter of the obtained mesoporous carbon is similar to the particle diameter of silicon dioxide in silica sol, and the pore diameter is larger and the specific surface area is smaller. The patent specification with the application number of CN200910152795.7 discloses a preparation method of acrylonitrile polymer based mesoporous carbon, which adopts ammonia water to adjust the pH of silica sol with the particle size of 5-20 nm, uses 2-amidinopropane to modify the silica sol, adds a carbon source and an emulsifying agent, and then carries out carbonization and a hydrofluoric acid silica removal template to obtain a mesoporous carbon product. The pore diameter of the mesoporous carbon obtained by the method can be adjusted within the range of 4-45 nm, the pore diameter is dependent on the particle size of silicon dioxide in silica sol, the mesoporous carbon with the synthetic pore diameter of less than 6nm is required to strictly require the particle size of a silicon template to be less than 8nm, and the method does not involve the treatment of hydrofluoric acid/fluosilicic acid waste liquid. Disclosure of Invention The invention provides a preparation process of mesoporous carbon with a recyclable silicon source and the mesoporous carbon obtained by the preparation process, and the obtained mesoporous carbon has the characteristics of high specific surface area, large pore volume and small pore diameter. The silicon template in the process of preparation has high cyclic utilization rate, the silicon recovery rate is more than 80 percent, waste acid and waste alkali liquid are basically not generated, and the mesoporous carbon product has good performances of high specific surface area, large pore volume, small pore diameter and the like, so that the mesoporous carbon product can be applied to the fields of electrode materials, shape selective catalysis, selective adsorption and the like with strict pore diameter requirements. A process for preparing mesoporous carbon with a recyclable silicon source, comprising: preparing a silicon template, namely reacting fluosilicic acid solution with calcium carbonate, and separating calcium fluoride precipitate and silica