Supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst and its preparation method

Abstract

This invention discloses a supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst and its preparation method. The preparation method includes: step (1) dissolving manganese salt and antimony precursor in deionized water to prepare a mixed salt solution, stirring and mixing evenly at room temperature, adding urea solution as a precipitant, then adding activated carbon and stirring and mixing evenly to obtain a hydrothermal precursor slurry; step (2) transferring the hydrothermal precursor slurry to a reactor for hydrothermal treatment, and after multiple centrifugation, washing and filtration, drying and grinding the obtained solid to obtain carbon-supported precursor powder; step (3) calcining the carbon-supported precursor powder in an inert atmosphere in a reactor, and obtaining the supported manganese antimonate denitrification catalyst after natural cooling. According to the preparation method of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst of this invention, the obtained catalyst has good sulfur poisoning resistance and high N2 selectivity.

Description

Technical Field

[0001] This invention relates to the field of industrial flue gas purification and environmental catalytic materials technology, and in particular to a supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst and its preparation method. Background Technology

[0002] With increasingly stringent environmental regulations, industrial flue gas nitrogen oxide emission standards are leaping from "ultra-low emissions" to "ultra-clean emissions" or "near-zero emissions." Simultaneously, the transformation of the energy structure necessitates frequent deep peak shaving by coal-fired power units, often resulting in flue gas temperatures at the economizer outlet dropping to 150℃ or even lower. Furthermore, after wet desulfurization, non-power industries such as steel, cement, and glass generally maintain flue gas temperatures in the low-temperature range (100-250℃). This situation poses a severe challenge to traditional medium-temperature SCR catalysts (such as V2O5-WO3 / TiO2, with an optimal activity window of 300-420℃), making the development of denitrification catalysts with excellent low-temperature activity an urgent industry need.

[0003] Among numerous low-temperature SCR candidate materials, manganese-based oxides (MnO) are... x Due to its unique variable valence properties (Mn) 2+ / Mn 3+ / Mn 4+ With its excellent low-temperature redox capabilities, manganese-based catalysts are widely recognized as one of the most promising low-temperature denitrification catalysts, exhibiting high denitrification activity in the 100-200℃ temperature range. However, in related technologies, manganese-based catalysts face two major bottlenecks on the road to industrial application: First, they are extremely sensitive to sulfur dioxide (SO2) and have poor resistance to sulfur poisoning. In sulfur-containing flue gas, SO2 is easily oxidized at the active sites of manganese to form thermodynamically stable manganese sulfate (MnSO4). This process irreversibly disrupts the catalyst's redox cycle, leading to permanent deactivation. Second, while manganese oxides exhibit high oxidizing power, they often accompany the over-oxidation of NH3, leading to an increase in the formation of the byproduct N2O and reducing the selectivity of the target product N2. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a method for preparing a supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst, wherein the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst prepared by the method exhibits good resistance to sulfur poisoning and high N2 selectivity.

[0005] The present invention also proposes a supported manganese antimonate ultra-low temperature sulfur and water resistant denitrification catalyst prepared by the above preparation method.

[0006] A method for preparing a supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to a first aspect of the present invention includes:

[0007] Step (1) Preparation of hydrothermal precursor slurry: Dissolve manganese salt and antimony precursor in deionized water to prepare a mixed salt solution. After stirring and mixing evenly at room temperature, add urea solution as a precipitant, then add activated carbon and stir and mix evenly to obtain the hydrothermal precursor slurry.

[0008] Step (2) Preparation of carbon-supported precursor powder: The hydrothermal precursor slurry obtained in step (1) is transferred to a reaction vessel for hydrothermal treatment. After the hydrothermal reaction is completed, the product is centrifuged, washed with deionized water and filtered multiple times. The resulting solid is dried and ground to obtain the carbon-supported precursor powder.

[0009] Step (3) Synthesis of supported manganese antimonate denitration catalyst: The carbon-supported precursor powder obtained in step (2) is placed in an inert atmosphere in a reactor and calcined. The carbothermic reduction process causes the carbon-supported precursor powder to be reduced and roasted in situ, and a dispersed composite metal oxide with MnSb2O4 as the main crystalline phase is formed on the surface of activated carbon. After natural cooling, the supported manganese antimonate denitration catalyst is obtained.

[0010] According to the preparation method of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst of the present invention, MnSb2O4 has a spinel structure, high chemical stability, and does not easily react with SO2, while Sb... 5+ The introduction of ions can also increase the total acidity on the catalyst surface, thereby inhibiting the competitive adsorption of acidic gas SO2 due to the enhanced acidity of the catalyst surface. By forming a dispersed composite metal oxide with MnSb2O4 as the main crystalline phase on the activated carbon surface, the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst exhibits good sulfur poisoning resistance. Furthermore, the electronic interaction between Mn and Sb can optimize the redox performance of manganese, maintaining high catalytic activity while inhibiting excessive oxidation of NH3 and reducing N2O generation, thus improving the N2 selectivity of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst. Loading MnSb2O4 onto activated carbon can also enhance the water resistance of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst.

[0011] According to some embodiments of the present invention, in step (1), the molar ratio of Mn:Sb is 1:0.1-1:1, and the total amount of urea added is 1.5-2.5 times the molar amount required for complete precipitation of metal ions.

[0012] According to some embodiments of the present invention, in step (1), the manganese salt is Mn(CH3COO)2·4H2O, Mn(NO3)2·6H2O or MnSO4·H2O; the antimony precursor is SbCl3, Sb2O3, Sb(NO3)3 or Sb(CH3COO)3.

[0013] According to some embodiments of the present invention, in step (1), the specific surface area of ​​the activated carbon is ≥1000 m². 2 / g, pore volume of activated carbon ≥0.8 cm³ 3 / g, the surface of activated carbon is pretreated with dilute nitric acid or hydrogen to increase oxygen-containing functional groups.

[0014] According to some embodiments of the present invention, in step (1), the amount of activated carbon added is 3:1-15:1 based on the mass ratio of activated carbon to total manganese and antimony metals, such that the active component accounts for 5wt%-20wt% of the total mass of the catalyst, and the active component is calculated as oxides of Mn and Sb.

[0015] According to some embodiments of the present invention, in step (2), the reactor is sealed and heated at a rate of 1-3 °C / min under autogenous pressure, the reactor rotation speed is 100-180 r / min, and the temperature is raised to 100-150 °C for 2-6 h; and / or, in step (2), the obtained solid is dried at 100-110 °C for 10-14 h.

[0016] According to some embodiments of the present invention, in step (3), the inert gas flow rate is controlled at 50-200 mL / min, the heating rate is 5-10℃ / min, and the carbothermic reduction reaction is carried out at 400-800℃ for 2-4 hours; and / or, the particle size of the composite metal oxide formed on the surface of activated carbon is 5-30 nm.

[0017] According to some embodiments of the present invention, in step (3), after carbothermic reduction, the mass content of MnSb2O4 crystal phase in the obtained composite metal oxide is not less than 60%.

[0018] According to a second aspect of the present invention, the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst is prepared by the preparation method described in the first aspect of the present invention.

[0019] The supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to embodiments of the present invention, prepared by the method of the first aspect of the present invention, exhibits good sulfur poisoning resistance, high N2 selectivity, and MnSb2O4 with a spinel structure, resulting in high chemical stability and minimal reaction with SO2. Sb... 5+The introduction of ions can also increase the total acidity on the catalyst surface, thereby inhibiting the competitive adsorption of acidic gas SO2 due to the enhanced acidity of the catalyst surface. By forming a dispersed composite metal oxide with MnSb2O4 as the main crystalline phase on the activated carbon surface, the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst exhibits good sulfur poisoning resistance. Furthermore, the electronic interaction between Mn and Sb can optimize the redox performance of manganese, maintaining high catalytic activity while inhibiting excessive oxidation of NH3 and reducing N2O generation, thus improving the N2 selectivity of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst. Loading MnSb2O4 onto activated carbon can also enhance the water resistance of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst.

[0020] According to some embodiments of the present invention, the catalyst has a denitrification rate of greater than 90%, and a denitrification efficiency of more than 85% after a 24-hour sulfur and water resistance test; and / or, the catalyst is suitable for low-temperature NH3-SCR denitrification processes in the fields of coal-fired power generation, steel sintering, cement kilns, glass furnaces and waste incineration flue gas, and the catalyst has high activity, high selectivity and sulfur and water resistance in the low-temperature range of 100-250℃.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 This is a schematic diagram of a method for preparing a supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to some embodiments of the present invention. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] The following is for reference. Figure 1 A method for preparing a supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to an embodiment of the present invention is described.

[0026] refer to Figure 1 The preparation method of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to the first aspect of the present invention includes:

[0027] Step (1) Preparation of hydrothermal precursor slurry: Manganese salt and antimony precursor are dissolved in deionized water to prepare a mixed salt solution. After stirring and mixing evenly at room temperature, urea solution is added as a precipitant. Activated carbon is then added and stirred and mixed evenly to obtain the hydrothermal precursor slurry. By adding urea solution as a precipitant, OH- is generated from urea hydrolysis. - The ionization process is relatively slow, and the pH value rises steadily, making the reaction process relatively mild. During the process of adding activated carbon and stirring to mix evenly, manganese ions and antimony ions mix with activated carbon and are loaded onto the surface of activated carbon.

[0028] Step (2) Preparation of carbon-supported precursor powder: The hydrothermal precursor slurry obtained in step (1) is transferred to the reactor for hydrothermal treatment. After the hydrothermal reaction is completed, the product is centrifuged, washed with deionized water and filtered multiple times. The resulting solid is dried and ground to obtain carbon-supported precursor powder. During the hydrothermal treatment, the precursor of manganese-antimony composite hydroxide can be generated in situ in the pores and surface of activated carbon and highly dispersed. The manganese ions and antimony ions loaded on the surface of activated carbon gradually precipitate into manganese and antimony hydroxides. The subsequent carbothermal reduction process is not only an activation step, but also an in-situ crystallization process, which makes the active component (MnSb2O4) form a strong chemical bond with the carbon support, effectively preventing the migration, aggregation and loss of the active component during use, and ensuring the long service life of the catalyst.

[0029] Step (3) Synthesis of supported manganese antimonate denitration catalyst: The carbon-supported precursor powder obtained in step (2) is placed in an inert atmosphere in a reactor and calcined. For example, the reactor can be a tube furnace or a muffle furnace, and the inert atmosphere can be nitrogen or argon. The carbothermic reduction process causes the carbon-supported precursor powder to be reduced and calcined in situ, and a dispersed composite metal oxide with MnSb2O4 as the main crystalline phase is formed on the surface of activated carbon. After natural cooling, the supported manganese antimonate denitration catalyst is obtained. During the carbothermic reduction process, the carbon-supported precursor powder is reduced in situ in an inert atmosphere to gradually generate manganese antimonate and manganese oxide. The active component (MnSb2O4) forms a strong chemical bond with the activated carbon support, which effectively prevents the migration, agglomeration and loss of the active component during use, and ensures the long service life of the catalyst.

[0030] Among them, MnSb2O4 is a composite metal oxide with a specific crystal structure, which is different from pure MnO. xThe electron cloud density and bond energy of the Mn-O bond in this composite oxide can be altered by the introduction of Sb, resulting in a higher energy barrier during its reaction with SO2. The MnSb2O4 formed by Sb and Mn possesses a spinel structure with high chemical stability. This structure itself exhibits strong resistance to sulfur poisoning and is less prone to reacting with SO2, thus thermodynamically and kinetically inhibiting the formation of manganese sulfate and resulting in better sulfur poisoning resistance of the catalyst. In the crystal structure of MnSb2O4, Sb... 5+ Ions possess high electronegativity and empty orbitals, making them strong Lewis acid sites (i.e., atomic or molecular regions adept at electron pair grabbing, exhibiting strong electron-accepting capabilities). Their introduction can increase the total acidity on the catalyst surface, particularly the number of Lewis acid sites. This not only enhances the adsorption and activation of the reactant NH3, improving low-temperature activity following the Eley-Rideal reaction mechanism (a key reaction pathway in heterogeneous catalysis where one reactant is first adsorbed onto the catalyst surface, while another reacts directly from the gas or liquid phase), but also inhibits the competitive adsorption of acidic gas SO2 due to the increased surface acidity of the catalyst, thus resulting in better sulfur poisoning resistance of the catalyst.

[0031] Furthermore, the electronic interactions between Mn and Sb can optimize the redox performance of manganese, maintaining high catalytic activity while inhibiting excessive oxidation of NH3 and reducing N2O formation, thereby improving the N2 selectivity of the catalyst. The activated carbon support itself has hydrophobic properties, which can enhance the water resistance of the MnSb2O4 material, resulting in better water resistance of the catalyst.

[0032] According to the preparation method of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst of the present invention, MnSb2O4 has a spinel structure, high chemical stability, and does not easily react with SO2, while Sb... 5+ The introduction of ions can also increase the total acidity on the catalyst surface, thereby inhibiting the competitive adsorption of acidic gas SO2 due to the enhanced acidity of the catalyst surface. By forming a dispersed composite metal oxide with MnSb2O4 as the main crystalline phase on the activated carbon surface, the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst exhibits good sulfur poisoning resistance. Furthermore, the electronic interaction between Mn and Sb can optimize the redox performance of manganese, maintaining high catalytic activity while inhibiting excessive oxidation of NH3 and reducing N2O generation, thus improving the N2 selectivity of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst. Loading MnSb2O4 onto activated carbon can also enhance the water resistance of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst.

[0033] According to some embodiments of the present invention, in step (1), the molar ratio of Mn:Sb is 1:0.1-1:1, and the total amount of urea added is 1.5-2.5 times the molar amount required for complete precipitation of metal ions.

[0034] For example, in step (1), the molar ratio of Mn:Sb can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.; the total amount of urea added can be 1.5 times, 2 times, 2.5 times, etc., the amount of molar amount required for complete precipitation of metal ions.

[0035] The metal ions in the solution are Mn 2+ and Sb 3+ The theoretical molar amount of urea required to completely precipitate metal ions is the amount of Mn in the solution that makes all the Mn in the solution... 2+ and Sb 3+ The molar amount of urea required to form a precipitate.

[0036] By setting the molar ratio of Mn:Sb to 1:0.1-1:1, manganese can be added in excess, making the supported manganese antimonate denitrification catalyst a composite metal oxide with MnSb2O4 as the main crystalline phase and doped with manganese oxide. By making the total amount of urea added 1.5-2.5 times the molar amount required for complete precipitation of metal ions, the hydrothermal precursor slurry can react more fully at the hydrothermal treatment site, thereby causing both manganese salt and antimony precursor to react and generate manganese and antimony hydroxides.

[0037] According to some embodiments of the present invention, in step (1), the manganese salt is Mn(CH3COO)2·4H2O, Mn(NO3)2·6H2O or MnSO4·H2O; the antimony precursor is SbCl3, Sb2O3, Sb(NO3)3 or Sb(CH3COO)3.

[0038] Among them, Mn(CH3COO)2·4H2O, Mn(NO3)2·6H2O, MnSO4·H2O, SbCl3, Sb2O3, Sb(NO3)3 and Sb(CH3COO)3 are all inexpensive and readily available materials.

[0039] By using Mn(CH3COO)2·4H2O, Mn(NO3)2·6H2O, or MnSO4·H2O as manganese salts and SbCl3, Sb2O3, Sb(NO3)3, or Sb(CH3COO)3 as antimony precursors, the production cost of supported manganese antimonate ultra-low temperature sulfur and water resistant denitrification catalysts can be reduced.

[0040] According to some embodiments of the present invention, in step (1), the specific surface area of ​​activated carbon is ≥1000m2 / g, the pore volume of activated carbon is ≥0.8 cm3 / g, and the surface of activated carbon is pretreated with dilute nitric acid or hydrogen to increase oxygen-containing functional groups.

[0041] For example, dilute nitric acid can be an aqueous solution of nitric acid with a mass fraction of less than 30%.

[0042] By increasing the specific surface area and pore volume of activated carbon, and pretreating its surface with dilute nitric acid or hydrogen to increase oxygen-containing functional groups, a synergistic adsorption effect on NH3 can be achieved, thereby reducing NO content in low-NO3 environments. x Under high concentration conditions, the catalyst surface can also accumulate a sufficient amount of NH3, thereby resulting in high catalytic efficiency of the supported manganese antimonate ultra-low temperature sulfur and water resistant denitrification catalyst.

[0043] According to some embodiments of the present invention, in step (1), the amount of activated carbon added is 3:1-15:1 based on the mass ratio of activated carbon to total manganese and antimony metals, such that the active component accounts for 5wt%-20wt% of the total mass of the catalyst, and the active component is calculated as oxides of Mn and Sb.

[0044] For example, in step (1), the ratio of the amount of activated carbon added to the total mass of manganese and antimony metal can be 3:1, 5:1, 7:1, 9:1, 11:1, 13:1, 15:1, etc. The total mass of manganese and antimony metal is the total theoretical mass of manganese and antimony elements in the solution, calculated based on the molar amounts of manganese salt and antimony precursor added.

[0045] By setting the mass ratio of activated carbon to total manganese and antimony metals to 3:1-15:1, and ensuring that the active component accounts for 5wt%-20wt% of the total catalyst mass, the surface of the activated carbon can be loaded with recombined active components, while avoiding excessive active components that could clog the pores on the surface of the activated carbon. This results in a high catalytic activity for the supported manganese antimony ultra-low temperature sulfur and water resistant denitrification catalyst.

[0046] According to some embodiments of the present invention, in step (2), the reactor is sealed and heated at a rate of 1-3℃ / min under autogenous pressure, the reactor rotation speed is 100-180r / min, and the temperature is raised to 100-150℃ for 2-6h.

[0047] Autogenous pressure is the phenomenon in a closed reaction system where the internal pressure spontaneously increases due to the generation of gas (or evaporation of liquid) by the chemical reaction itself.

[0048] For example, in step (2), the heating rate for sealing the reactor can be 1℃ / min, 2℃ / min, 3℃ / min, etc.; the reactor rotation speed can be 100r / min, 120r / min, 140r / min, 160r / min, 180r / min, etc.; the heating temperature can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, etc.; and the reaction time can be 2h, 3h, 4h, 5h, 6h, etc.

[0049] By setting the heating rate of the reactor to 1-3℃ / min and the reactor rotation speed to 100-180r / min, and heating to 100-150℃ for 2-6 hours, activated carbon and urea can be mixed evenly and reacted fully, thereby allowing the manganese salt and antimony precursor loaded in the pores of the activated carbon to fully react and generate manganese and antimony hydroxides.

[0050] According to some embodiments of the present invention, in step (2), the resulting solid is dried at 100-110°C for 10-14 hours.

[0051] For example, the drying temperature of the obtained solid can be 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, etc.; the drying time of the obtained solid can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, etc.

[0052] By drying the obtained solid at 100-110℃ for 10-14 hours, the deionized water in the solid can be completely removed, which makes it easier to grind the solid to obtain carbon-supported precursor powder. It can also avoid oxidation of the carbon-supported precursor powder at excessively high temperatures and times.

[0053] According to some embodiments of the present invention, in step (3), the inert gas flow rate is controlled at 50-200 mL / min, the heating rate is 5-10℃ / min, and the carbothermic reduction reaction is carried out at 400-800℃ for 2-4 hours.

[0054] For example, in step (3), the inert gas flow rate can be controlled to 50 mL / min, 100 mL / min, 150 mL / min, 200 mL / min, etc.; the heating rate can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, etc.; the carbothermic reduction reaction temperature can be 400℃, 500℃, 600℃, 700℃, 800℃, etc.; and the carbothermic reduction reaction time can be 2 hours, 3 hours, 4 hours, etc.

[0055] By controlling the inert gas flow rate to 50-200 mL / min and the heating rate to 5-10℃ / min, and heating to 400-800℃ for 2-4 hours for carbothermic reduction reaction, carbon-supported precursor powder can be stably converted into activated carbon-supported composite metal oxide with MnSb2O4 as the main crystalline phase, avoiding catalyst deactivation caused by excessively long calcination time or excessively high calcination temperature.

[0056] According to some embodiments of the present invention, in step (3), the particle size of the composite metal oxide formed on the surface of the activated carbon is 5-30 nm.

[0057] By making the particle size of the composite metal oxide formed on the surface of activated carbon 5-30 nm, the composite metal oxide with MnSb2O4 as the main crystalline phase can be more dispersed on the surface of activated carbon. This allows for a stronger chemical bond between the composite metal oxide and the carbon support, preventing the migration, aggregation, and loss of active components during use, and ensuring the long service life of the supported manganese antimonate ultra-low temperature sulfur and water resistant denitrification catalyst.

[0058] According to some embodiments of the present invention, in step (3), after carbothermic reduction, the mass content of MnSb2O4 crystal phase in the obtained composite metal oxide is not less than 60%.

[0059] For example, after carbothermic reduction, the mass content of the MnSb2O4 crystal phase in the resulting composite metal oxide can be 60%, 65%, 70%, etc.

[0060] By ensuring that the mass content of the MnSb2O4 crystal phase in the obtained composite metal oxide is not less than 60%, and by utilizing the stability of MnSb2O4 and its resistance to sulfur reaction, the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst can be made to have strong resistance to sulfur poisoning.

[0061] The supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to the second aspect of the present invention is prepared by the preparation method according to the first aspect of the present invention.

[0062] The supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to embodiments of the present invention, prepared by the method of the first aspect of the present invention, exhibits good sulfur poisoning resistance, high N2 selectivity, and MnSb2O4 with a spinel structure, resulting in high chemical stability and minimal reaction with SO2. Sb... 5+The introduction of ions can also increase the total acidity on the catalyst surface, thereby inhibiting the competitive adsorption of acidic gas SO2 due to the enhanced acidity of the catalyst surface. By forming a dispersed composite metal oxide with MnSb2O4 as the main crystalline phase on the activated carbon surface, the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst exhibits good sulfur poisoning resistance. Furthermore, the electronic interaction between Mn and Sb can optimize the redox performance of manganese, maintaining high catalytic activity while inhibiting excessive oxidation of NH3 and reducing N2O generation, thus improving the N2 selectivity of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst. Loading MnSb2O4 onto activated carbon can also enhance the water resistance of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst.

[0063] According to some embodiments of the present invention, the catalyst achieves a denitrification rate greater than 90%, and a denitrification efficiency of over 85% after a 24-hour sulfur and water resistance test. This allows the supported manganese antimonate cryogenic sulfur and water resistant denitrification catalyst to maintain its catalytic activity for a longer period, resulting in a longer service life.

[0064] According to some embodiments of the present invention, the catalyst is suitable for low-temperature NH3-SCR denitrification processes in coal-fired power generation, steel sintering, cement kilns, glass furnaces, and waste incineration flue gas fields. The catalyst has high activity, high selectivity, and sulfur and water resistance in the low-temperature range of 100-250°C.

[0065] By enabling the supported manganese antimonate ultra-low temperature sulfur and water resistant denitrification catalyst to exhibit high activity, high selectivity, and sulfur and water resistance in the low temperature range of 100-250℃, the formation and deposition of ammonium sulfate salts are reduced. This allows the catalyst to exhibit stronger catalytic activity when used for denitrification of low-temperature flue gas, reduces the occurrence of catalyst deactivation due to sulfur poisoning and water poisoning, and extends the catalyst's lifespan.

[0066] The following is for reference. Figure 1 The preparation method of the supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst of the present invention will be further explained with reference to the embodiments.

[0067] Example 1,

[0068] refer to Figure 1 In this embodiment, the preparation method of the supported sulfur- and water-resistant manganese antimony oxide (MnSb2O4) ultra-low temperature denitration catalyst includes the following steps:

[0069] First, 12.25 g of Mn(CH3COO)2·4H2O and 5.71 g of SbCl3 were weighed and dissolved in 200 mL of deionized water. The solution was magnetically stirred until completely dissolved, yielding a mixed salt solution with a Mn:Sb molar ratio of 1:0.5. Then, 87.5 mL of a 2 mol / L urea solution (total urea being twice the theoretical precipitate amount) was slowly added under continuous stirring. Next, 30 g of coconut shell activated carbon pretreated with dilute nitric acid (with a specific surface area of ​​approximately 1200 m²) was added. 2 / g, pore volume approximately 1.0 cm³ 3 / g), continue stirring for 2 hours to form a uniform slurry; then transfer the slurry to a 500 mL PTFE-lined stainless steel reactor, seal it, and place it in an oven to heat to 120°C at 2°C / min, and maintain the temperature at 150 r / min for 4 hours for hydrothermal reaction; after the reaction, allow it to cool naturally to room temperature, centrifuge the product, wash it three times with deionized water and filter it, dry the resulting filter cake in a 105°C forced-air drying oven for 12 hours and grind it to obtain black manganese-antimony composite precursor supported activated carbon powder; finally, take 20 g of the dried powder and spread it evenly in a quartz boat, place it in the central heating zone of a tube furnace, purge it with high-purity nitrogen (flow rate 100 mL / min) for 30 minutes to remove air, heat it to 500°C at 3°C / min and maintain carbothermal reduction for 3 hours, after the reaction, allow it to cool naturally to room temperature under a nitrogen atmosphere to obtain the supported sulfur- and water-resistant manganese antimony ultra-low temperature denitrification catalyst, whose active component loading is about 15 wt% (based on Mn and Sb oxides). The catalyst has a denitrification efficiency of over 95% at temperatures above 130℃ and a denitrification efficiency of over 90% after 24 hours of sulfur and water resistance stability testing.

[0070] Example 2,

[0071] refer to Figure 1 The difference between this embodiment and Embodiment 1 is that the molar ratio of Mn to Sb is adjusted to 1:1.

[0072] The specific preparation steps are as follows: First, weigh 12.25 g of Mn(CH3COO)2·4H2O and 11.41 g of SbCl3 and dissolve them in 200 mL of deionized water. Stir magnetically until completely dissolved to obtain a mixed salt solution with a Mn:Sb molar ratio of 1:1. Then, slowly add 87.5 mL of urea solution with a concentration of 2 mol / L (the total amount of urea is twice the theoretical precipitation amount) while continuously stirring. Next, add 30 g of coconut shell activated carbon pretreated with dilute nitric acid (specific surface area of ​​approximately 1200 m²). 2 / g, pore volume approximately 1.0 cm³ 3 / g), continue stirring for 2 hours to form a uniform slurry; then transfer the slurry to a 500 mL PTFE-lined stainless steel reactor, seal it, and place it in an oven to heat to 120°C at 2°C / min, and maintain the temperature at 150 r / min for 4 hours for hydrothermal reaction; after the reaction, allow it to cool naturally to room temperature, centrifuge the product, wash it three times with deionized water and filter it, dry the resulting filter cake in a 105°C forced-air drying oven for 12 hours and grind it to obtain black manganese-antimony composite precursor supported activated carbon powder; finally, take 20 g of the dried powder and spread it evenly in a quartz boat, place it in the central heating zone of a tube furnace, purge with high-purity nitrogen (flow rate 100 mL / min) for 30 minutes to remove air, heat to 500°C at 3°C / min and maintain carbothermal reduction for 3 hours, after the reaction, allow it to cool naturally to room temperature under a nitrogen atmosphere to obtain the supported sulfur- and water-resistant manganese antimony ultra-low temperature denitrification catalyst, whose active component loading is about 18 wt% (based on Mn and Sb oxides). The catalyst has a denitrification efficiency of over 97% at temperatures above 130℃ and a denitrification efficiency of over 92% after 24 hours of sulfur and water resistance stability testing.

[0073] Example 3,

[0074] refer to Figure 1 The difference between this embodiment and Embodiment 1 is that the temperature of the hydrothermal treatment is adjusted to 150°C.

[0075] The specific preparation steps are as follows: First, weigh 12.25 g of Mn(CH3COO)2·4H2O and 5.71 g of SbCl3 and dissolve them in 200 mL of deionized water. Stir magnetically until completely dissolved to obtain a mixed salt solution with a Mn:Sb molar ratio of 1:1. Then, slowly add 87.5 mL of a 2 mol / L urea solution (the total amount of urea is twice the theoretical precipitate) while continuously stirring. Next, add 30 g of coconut shell activated carbon pretreated with dilute nitric acid (specific surface area of ​​approximately 1200 m² / g, pore volume of approximately 1.0 cm³). 3 / g), continue stirring for 2 hours to form a uniform slurry; then transfer the slurry to a 500 mL PTFE-lined stainless steel reactor, seal it, and place it in an oven to heat to 150 °C at 2 °C / min, and maintain the temperature at 150 r / min for 4 hours for hydrothermal reaction; after the reaction, allow it to cool naturally to room temperature, centrifuge the product, wash it three times with deionized water and filter it, dry the resulting filter cake in a 105 °C forced-air drying oven for 12 hours and grind it to obtain black manganese-antimony composite precursor supported activated carbon powder; finally, take 20 g of the dried powder and spread it evenly in a quartz boat, place it in the central heating zone of a tube furnace, purge it with high-purity nitrogen (flow rate 100 mL / min) for 30 minutes to remove air, heat it to 500 °C at 3 °C / min and maintain carbothermal reduction for 3 hours, after the reaction, allow it to cool naturally to room temperature under a nitrogen atmosphere to obtain the supported sulfur- and water-resistant manganese antimony ultra-low temperature denitrification catalyst, whose active component loading is about 15 wt% (based on oxides of Mn and Sb). The catalyst has a denitrification efficiency of over 91% at temperatures above 130℃ and a denitrification efficiency of over 89% after 24 hours of sulfur and water resistance stability testing.

[0076] Example 4,

[0077] refer to Figure 1 The difference between this embodiment and Embodiment 1 is that the carbothermal reduction temperature is adjusted to 800°C.

[0078] The specific preparation steps are as follows: First, weigh 12.25 g of Mn(CH3COO)2·4H2O and 5.71 g of SbCl3 and dissolve them in 200 mL of deionized water. Stir magnetically until completely dissolved to obtain a mixed salt solution with a Mn:Sb molar ratio of 1:1. Then, slowly add 87.5 mL of 2 mol / L urea solution (the total amount of urea is twice the theoretical precipitate amount) while continuously stirring. Next, add 30 g of coconut shell activated carbon pretreated with dilute nitric acid (specific surface area of ​​approximately 1200 m²). 2 / g, pore volume approximately 1.0 cm³ 3 / g), continue stirring for 2 hours to form a uniform slurry; then transfer the slurry to a 500 mL PTFE-lined stainless steel reactor, seal it, and place it in an oven to heat to 120°C at 2°C / min, and maintain the temperature at 150 r / min for 4 hours for hydrothermal reaction; after the reaction, allow it to cool naturally to room temperature, centrifuge the product, wash it three times with deionized water and filter it, dry the resulting filter cake in a 105°C forced-air drying oven for 12 hours and grind it to obtain black manganese-antimony composite precursor supported activated carbon powder; finally, take 20 g of the dried powder and spread it evenly in a quartz boat, place it in the central heating zone of a tube furnace, purge it with high-purity nitrogen (flow rate 100 mL / min) for 30 minutes to remove air, heat it to 800°C at 3°C / min and maintain carbothermal reduction for 3 hours, after the reaction, allow it to cool naturally to room temperature under a nitrogen atmosphere to obtain the supported sulfur- and water-resistant manganese antimony ultra-low temperature denitrification catalyst, whose active component loading is about 15 wt% (based on oxides of Mn and Sb). The catalyst has a denitrification efficiency of over 94% at temperatures above 130℃ and a denitrification efficiency of over 90% after 24 hours of sulfur and water resistance stability testing.

[0079] Comparative Example 1,

[0080] The catalyst was prepared using a traditional impregnation method. MnO was supported on nitric acid-modified activated carbon (AC). x Catalyst preparation using active components: 30g of nitric acid-modified activated carbon was weighed and impregnated in a manganese nitrate solution (the concentration of manganese nitrate was determined according to the mass fraction of Mn loaded). The carbon was ultrasonically treated for 2 hours, then allowed to stand for 12 hours. After drying at 110℃ for 12 hours, it was placed in a tube furnace and calcined in air at 500℃ for 4 hours to obtain MnO. x / AC catalyst. The catalyst has a denitrification efficiency of over 90% at temperatures above 130℃, and a denitrification efficiency of approximately 55% after a 24-hour sulfur and water resistance stability test.

[0081] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0082] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0083] In the description of this invention, "a plurality of" means two or more.

[0084] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0085] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0086] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0087] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst, characterized in that, include: Step (1) Preparation of hydrothermal precursor slurry: Dissolve manganese salt and antimony precursor in deionized water to prepare a mixed salt solution. After stirring and mixing evenly at room temperature, add urea solution as a precipitant, then add activated carbon and stir and mix evenly to obtain the hydrothermal precursor slurry. The molar ratio of Mn:Sb is 1:0.1-1:

1. The amount of activated carbon added is 3:1-15:1 based on the mass ratio of activated carbon to total manganese and antimony metals, so that the active component accounts for 5wt%-20wt% of the total mass of the catalyst. The active component is calculated as oxides of Mn and Sb. Step (2) Preparation of carbon-supported precursor powder: The hydrothermal precursor slurry obtained in step (1) is transferred to a reactor for hydrothermal treatment. After the hydrothermal reaction is completed, the product is centrifuged, washed with deionized water and filtered multiple times. The resulting solid is dried and ground to obtain the carbon-supported precursor powder. Step (3) Synthesis of supported manganese antimonate denitration catalyst: The carbon-supported precursor powder obtained in step (2) is placed in an inert atmosphere in a reactor and calcined. The carbothermic reduction process causes the carbon-supported precursor powder to be reduced and calcined in situ, and a composite metal oxide with MnSb2O4 as the main crystalline phase and doped with manganese oxide is formed on the surface of activated carbon. After natural cooling, the supported manganese antimonate denitration catalyst is obtained. The inert gas flow rate is controlled at 50-200 mL / min, the heating rate is 5-10℃ / min, and the carbothermic reduction reaction is carried out at 400-800℃ for 2-4 hours.

2. The preparation method according to claim 1, characterized in that, The total amount of urea added is 1.5-2.5 times the molar amount required for complete precipitation of metal ions.

3. The preparation method according to claim 1, characterized in that, In step (1), the manganese salt is Mn(CH3COO)2·4H2O, Mn(NO3)2·6H2O or MnSO4·H2O; the antimony precursor is SbCl3, Sb2O3, Sb(NO3)3 or Sb(CH3COO)3.

4. The preparation method according to claim 1, characterized in that, In step (1), the specific surface area of ​​the activated carbon is ≥1000 m². 2 / g, pore volume of activated carbon ≥0.8 cm³ 3 / g, the surface of activated carbon is pretreated with dilute nitric acid or hydrogen to increase oxygen-containing functional groups.

5. The preparation method according to claim 1, characterized in that, In step (2), the reactor is sealed and heated at a rate of 1-3℃ / min under autogenous pressure. The reactor rotation speed is 100-180r / min, and the temperature is raised to 100-150℃ for 2-6 hours. And / or, in step (2), the resulting solid is dried at 100-110°C for 10-14 hours.

6. The preparation method according to claim 1, characterized in that, In step (3), the particle size of the composite metal oxide formed on the surface of activated carbon is 5-30 nm.

7. The preparation method according to any one of claims 1-6, characterized in that, In step (3), after carbothermic reduction, the mass content of MnSb2O4 crystal phase in the resulting composite metal oxide is not less than 60%.

8. A supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst, characterized in that, The supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst is prepared by the preparation method according to any one of claims 1-7.

9. The supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to claim 8, characterized in that, The catalyst has a denitrification rate of over 90%, and its denitrification efficiency is over 85% after a 24-hour sulfur and water resistance test.

10. The supported manganese antimonate ultra-low temperature sulfur- and water-resistant denitrification catalyst according to claim 8, characterized in that, The catalyst is suitable for low-temperature NH3-SCR denitrification processes in coal-fired power generation, steel sintering, cement kilns, glass furnaces, and waste incineration flue gas fields. The catalyst has high activity, high selectivity, and sulfur and water resistance in the low-temperature range of 100-250℃.

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