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CN-121988408-A - Ammonia-free ultralow-temperature denitration catalyst and preparation method thereof

CN121988408ACN 121988408 ACN121988408 ACN 121988408ACN-121988408-A

Abstract

The invention provides an ammonia-free ultralow-temperature denitration catalyst and a preparation method thereof, and the ammonia-free ultralow-temperature denitration catalyst comprises the following steps of S1, mixing manganese nitrate, cerium nitrate and niobium oxalate according to the mass ratio of 80-90:5-10:5-10 to obtain mixed powder, adding absolute ethyl alcohol into the mixed powder, mixing, ball milling to obtain activated powder, placing the activated powder, water and citric acid into a reaction kettle for hydrothermal reaction, carrying out suction filtration to obtain an active substance after the reaction, S2, mixing the active substance, nano titanium sol, nano silicon sol and tween-20 according to the mass ratio of 20-40:45-65:5-15:3-7 to obtain a coating material, coating the coating material on a pretreated cordierite carrier, and then drying and roasting to obtain the ammonia-free ultralow-temperature denitration catalyst. According to the invention, mixed powder is subjected to ball milling activation and then subjected to hydrothermal reaction to form the nano needle-shaped oxide, so that the denitration activity of the catalyst in an ammonia-free low-temperature environment can be greatly increased.

Inventors

  • XU KUI
  • XU HUI
  • Meng Dongxiang
  • YANG YONGPING
  • Xia Mengya
  • WANG GUANGYING
  • XU XIAOLONG
  • SHENG DI

Assignees

  • 安徽元琛环保科技股份有限公司

Dates

Publication Date
20260508
Application Date
20260122

Claims (10)

  1. 1. The preparation method of the ammonia-free ultralow-temperature denitration catalyst is characterized by comprising the following steps of: S1, mixing manganese nitrate, cerium nitrate and niobium oxalate according to the mass ratio of 80-90:5-10:5-10 to obtain mixed powder, adding absolute ethyl alcohol into the mixed powder, mixing, performing ball milling to obtain activated powder, placing the activated powder, water and citric acid into a reaction kettle for hydrothermal reaction, and performing suction filtration after the reaction to obtain an active substance; S2, mixing an active substance, nano titanium sol, nano silica sol and tween-20 according to a mass ratio of 20-40:45-65:5-15:3-7 to obtain a coating material, coating the coating material on a pretreated cordierite carrier, and drying and roasting to obtain the ammonia-free ultralow-temperature denitration catalyst.
  2. 2. The method for preparing the ammonia-free ultralow-temperature denitration catalyst according to claim 1, wherein the solid-to-liquid ratio of the activated powder to water is 1:20-80.
  3. 3. The method for preparing the ammonia-free ultralow-temperature denitration catalyst according to claim 1, wherein the mass ratio of the mixed powder to the citric acid is 100:2-10.
  4. 4. The method for preparing the ammonia-free ultralow-temperature denitration catalyst according to claim 1, wherein the mass ratio of the mixed powder to the absolute ethyl alcohol is 100:9-11.
  5. 5. The method for preparing the ammonia-free ultralow-temperature denitration catalyst according to claim 1, wherein the cordierite carrier is soaked in an ammonium dihydrogen phosphate solution with the mass fraction of 1% -5% for 60 min-120 min to obtain the pretreated cordierite carrier.
  6. 6. The method for preparing the ammonia-free ultralow temperature denitration catalyst according to claim 1, wherein the loading amount of the ammonia-free ultralow temperature denitration catalyst is 70-150 g/L.
  7. 7. The method for preparing the ammonia-free ultralow-temperature denitration catalyst according to claim 1, wherein the temperature of the hydrothermal reaction is 140-150 ℃ and the reaction time is 4-9 hours.
  8. 8. The method for preparing the ammonia-free ultralow temperature denitration catalyst according to claim 1, wherein the drying temperature is 100-105 ℃ and the drying time is 4 hours.
  9. 9. The method for preparing the ammonia-free ultralow-temperature denitration catalyst according to claim 1, wherein the roasting temperature is 200-350 ℃ and the roasting time is 1-3 h.
  10. 10. An ammonia-free ultra-low temperature denitration catalyst prepared by the method for preparing an ammonia-free ultra-low temperature denitration catalyst as claimed in any one of claims 1 to 9.

Description

Ammonia-free ultralow-temperature denitration catalyst and preparation method thereof Technical Field The invention relates to the field of denitration catalysts, in particular to an ammonia-free ultralow-temperature denitration catalyst and a preparation method thereof. Background Nitrogen oxides (NOx) are one of the major atmospheric pollutants produced in industrial processes, which can lead to the generation of photochemical smog and acid rain. The SNCR and SCR technology is generally adopted to remove NOx, but ammonia as a reducing agent used in the technology can generate ammonia escape at the denitration end, and the ammonia escape is more serious especially under the low-temperature flue gas working condition, so that the problems of corrosion of equipment pipelines and secondary pollution of the atmosphere are caused. The current mainstream SCR denitration technology is NH 3 -SCR, ammonia and NOx are converted into nitrogen in the V 2O5-WO3(MoO3)/TiO2 denitration catalyst, its reaction temperature window is generally high (200-400 ℃) and has little capability of ammonia-free denitration (CO-SCR), and the spent catalyst containing V 2O5 belongs to hazardous waste and needs special treatment. The environment-friendly Mn-based denitration catalyst has excellent low-temperature SCR denitration performance, and can effectively reduce the concentration of NOx in the flue gas under the working condition that NH 3 or CO is used as a reducing agent, but has lower denitration catalytic activity. Disclosure of Invention The invention aims to solve the technical problem of how to improve the denitration activity of the ammonia-free ultralow-temperature denitration catalyst at low temperature. The invention solves the technical problems by the following technical means: the invention provides a preparation method of an ammonia-free ultralow-temperature denitration catalyst, which comprises the following steps of: S1, mixing manganese nitrate, cerium nitrate and niobium oxalate according to the mass ratio of 80-90:5-10:5-10 to obtain mixed powder, adding absolute ethyl alcohol into the mixed powder, mixing, performing ball milling to obtain activated powder, placing the activated powder, water and citric acid into a reaction kettle for hydrothermal reaction, and performing suction filtration after the reaction to obtain an active substance; S2, mixing an active substance, nano titanium sol, nano silica sol and tween-20 according to a mass ratio of 20-40:45-65:5-15:3-7 to obtain a coating material, coating the coating material on a pretreated cordierite carrier, and drying and roasting to obtain the ammonia-free ultralow-temperature denitration catalyst. The preparation method has the beneficial effects that in the preparation of the ammonia-free ultralow-temperature denitration catalyst, firstly, mixed powder is subjected to ball milling activation, then nano needle-shaped active substances are generated through hydrothermal reaction, and finally, the nano needle-shaped active substances and auxiliary agents are mixed and then coated on a cordierite carrier to form the honeycomb-shaped coating ammonia-free ultralow-temperature denitration catalyst. The invention not only can reduce particles and crystal grains of the mixed powder to increase the surface reaction activity, but also can reduce lattice dislocation and distortion to reduce crystal boundary and increase the area of the crystal boundary to generate amorphous phase, thereby increasing amorphous Gibbs free energy, dislocation Gibbs free energy, surface Gibbs free energy and crystal boundary Gibbs free energy to further increase the reaction activity of the mixed powder, thereby being beneficial to the subsequent hydrothermal reaction, and can also convert a small part of mechanical energy into energy storage of the mixed powder to reduce the activation energy thereof, thereby being beneficial to the subsequent hydrothermal reaction. The mixed powder is oxidized and grown into nano needle-shaped oxide in the hydrothermal reaction, so that the denitration activity of the catalyst in the ammonia-free low-temperature environment can be greatly increased. Preferably, the ball milling time is 180-220 min. Preferably, the solid-to-liquid ratio of the activated powder to water is 1:20-80. Preferably, the solid to liquid ratio of the activated powder to water may be 1:30, 1:50, 1:70, etc. Preferably, the mass ratio of the mixed powder to the citric acid is 100:2-10. Preferably, the mass ratio of the mixed powder to the citric acid can be 100:3, 100:5, 100:7, etc. Preferably, the mass ratio of the mixed powder to the absolute ethyl alcohol is 100:9-11. Preferably, the mass fraction of the nano titanium sol is 15%. Preferably, the mass fraction of the nano silica sol is 30%. Preferably, the cordierite carrier is soaked in an ammonium dihydrogen phosphate solution with the mass fraction of 1% -5% for 60-120 min to obtain the pretreated cordierite carrier. Preferabl