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CN-121990829-A - Silicon carbide ceramic and preparation method and application thereof

CN121990829ACN 121990829 ACN121990829 ACN 121990829ACN-121990829-A

Abstract

The invention belongs to the technical field of catalysts, and discloses silicon carbide ceramic, a preparation method and application thereof, wherein the silicon carbide ceramic is obtained by sintering in air at a temperature of 1000-1400 ℃, raw materials of the silicon carbide ceramic comprise submicron silicon carbide powder, optional 50-mu m silicon carbide powder, a binder and a dispersing agent, and the content of the submicron silicon carbide powder is 5-90wt%, the content of the 50-mu m silicon carbide powder is 0-90wt%, the content of the binder is 3-30wt% and the content of the dispersing agent is 0.1-5wt% based on the total weight of the submicron silicon carbide powder, the 50-mu m silicon carbide powder, the binder and the dispersing agent. The silicon carbide ceramic provided by the invention can be used as a catalyst carrier and a catalyst bed diluent, and is low in preparation cost.

Inventors

  • DING CHENGZHE
  • LI WEI
  • BAI JIE
  • WU JIEHUA
  • WANG XUE
  • WU SANMIN

Assignees

  • 中国石油化工股份有限公司
  • 中石化(北京)化工研究院有限公司

Dates

Publication Date
20260508
Application Date
20241107

Claims (10)

  1. 1. A silicon carbide ceramic, characterized in that the silicon carbide ceramic is obtained by sintering in air at 1000-1400 ℃, and the raw materials comprise submicron silicon carbide powder, optional 50 μm silicon carbide powder, a binder and a dispersing agent; The submicron silicon carbide powder comprises 5-90wt%, 50 μm silicon carbide powder comprises 0-90wt%, binder comprises 3-30wt% and dispersant comprises 0.1-5wt%, based on the total weight of the submicron silicon carbide powder, 50 μm silicon carbide powder, binder and dispersant.
  2. 2. A silicon carbide ceramic as claimed in claim 1, wherein the submicron silicon carbide powder is present in an amount of 10 to 85wt%, the 50 μm silicon carbide powder is present in an amount of 0 to 80wt%, the binder is present in an amount of 5 to 25wt%, and the dispersant is present in an amount of 0.5 to 5wt%, based on the total weight of submicron silicon carbide powder, 50 μm silicon carbide powder, binder and dispersant.
  3. 3. The silicon carbide ceramic as claimed in claim 1, wherein the binder is selected from at least one of polyvinyl alcohol, hydroxypropyl methylcellulose and starch.
  4. 4. A silicon carbide ceramic according to claim 1 wherein the dispersant is polyethylene glycol and/or polyvinylpyrrolidone.
  5. 5. The silicon carbide ceramic as claimed in claim 1, wherein the compressive strength of the silicon carbide ceramic is 10 to 50N/mm, the silicon carbide phase content is 20 to 85%, and the porosity is 10 to 25%.
  6. 6. The method for producing a silicon carbide ceramic according to any one of claims 1 to 5, comprising the steps of: (a) Mixing submicron silicon carbide powder, optional 50 mu m silicon carbide powder, a binder, a dispersing agent and water, stirring, and drying to obtain ceramic granulating powder; (b) Shaping ceramic granulating powder to obtain a ceramic blank; (c) Roasting the ceramic blank in air at 1000-1400 deg.c for 0.5-3 hr to obtain silicon carbide ceramic.
  7. 7. The method for producing a silicon carbide ceramic according to claim 6, wherein the mass ratio of the total mass of the submicron silicon carbide powder, optional 50 μm silicon carbide powder, binder and dispersant to water is 1:1-10.
  8. 8. The method for producing a silicon carbide ceramic according to claim 6, wherein the stirring is strong stirring for 1 to 6 hours.
  9. 9. The method for producing silicon carbide ceramic according to claim 6, wherein the drying is spray drying, the feed flow rate is 2 to 4mL/min, and the hot air inlet temperature is 130 to 200 ℃.
  10. 10. Use of the silicon carbide ceramic according to any one of claims 1-5 in chemical catalytic reactions.

Description

Silicon carbide ceramic and preparation method and application thereof Technical Field The invention belongs to the technical field of catalysts, and particularly relates to silicon carbide ceramic, a preparation method of the silicon carbide ceramic and application of the silicon carbide ceramic. Background Silicon carbide is widely focused in the field of chemical catalysis due to the characteristics of high thermal conductivity, high mechanical strength, high wear resistance, low thermal expansion coefficient, chemical inertness and the like, and is a preferred material for a catalyst carrier and a catalytic bed filler for strong heat absorption and release reactions. However, the application of silicon carbide in the catalysis field is limited by the high production cost, and the formed silicon carbide ceramic is difficult to popularize. The Si-C bond energy in the silicon carbide is stronger (300 kJ/mol), so that the temperature of the silicon carbide for direct sintering in an inert atmosphere needs 2100-2200 ℃, and the energy consumption and the equipment cost are greatly increased. At present, the most widely used liquid phase sintering process is adopted, and an Al 2O3-Y2O3 sintering aid is used for reducing the sintering temperature of silicon carbide to about 1950 ℃, and the principle is that a Y 3Al5O12 eutectic compound is formed at 1930 ℃, so that silicon carbide ceramic particles are rearranged, and densification is realized. After the liquid phase sintering process, the hardness of the silicon carbide ceramic is greatly improved, but the sintering cost is still high, the silicon carbide ceramic is mostly used in the fields of aerospace, military industry and the like, and the popularization rate of the silicon carbide ceramic in the field of chemical catalysis is relatively low. Meanwhile, substances containing acidic sites, such as Al 2O3, are introduced, which may exacerbate the generation of carbon deposition in the catalytic process. Therefore, the development of the preparation process of the silicon carbide ceramic, which can further reduce the sintering temperature, has important value in the field of catalysis. Notably, the chemical catalysis field requires relatively low mechanical strength for silicon carbide compared to the aerospace field, which requires hundreds of MPa of flexural strength for silicon carbide. For a fixed bed reactor, solid particles mainly need to bear the impact during transportation and filling, the weight of the catalyst and the pressure drop in the reaction process, and the radial compressive strength of the catalyst reaches 10-20N/mm to meet the requirements of most gas phase reaction catalysts, so that the corresponding silicon carbide is far lower than the requirements of the aerospace field in terms of strength no matter serving as a carrier and a diluent. Compared with the mechanical strength, the phase content of silicon carbide in the catalysis field is more important for the heat conduction performance and chemical stability which are endowed with the phase content. Thus, by appropriate methods, the preparation of silicon carbide is critical for its use in catalysis, with mechanical strength balanced with economy, while maintaining the chemical inertness of the material. Disclosure of Invention Based on the above, the invention aims to provide a silicon carbide ceramic and a preparation method and application thereof, and the preparation method can obviously improve the compressive strength of the ceramic and meet the requirements of a catalytic bed layer on the basis of keeping most silicon carbide phases. Meanwhile, as substances with acid sites such as alumina are not introduced, the chemical inertness of silicon carbide can be kept, and side reactions caused by high-temperature catalytic reaction are avoided. In a first aspect, the present invention provides a silicon carbide ceramic obtained by sintering in air at a temperature of 1000-1400 ℃, wherein the raw materials comprise submicron silicon carbide powder, optional 50 μm silicon carbide powder, a binder and a dispersing agent; the submicron silicon carbide powder comprises 5-90wt%, 50 μm silicon carbide powder comprises 0-90wt%, binder comprises 3-30wt% and dispersant comprises O.1-5wt%, based on the total weight of the submicron silicon carbide powder, 50 μm silicon carbide powder, binder and dispersant. The second aspect of the present invention provides a method for preparing the silicon carbide ceramic, which comprises the following steps: (a) Mixing submicron silicon carbide powder, optional 50 mu m silicon carbide powder, a binder, a dispersing agent and water, stirring, and drying to obtain ceramic granulating powder; (b) Shaping ceramic granulating powder to obtain a ceramic blank; (c) Roasting the ceramic blank in air at 1000-1400 deg.c for 0.5-3 hr to obtain silicon carbide ceramic. The third aspect of the invention provides the application of the silicon carbide ceramic in chemi