A denitration catalyst and a method for preparing the same

Abstract

The present application attempts to provide a denitration catalyst and a preparation method thereof, the preparation method comprising: step 1: a certain amount of polyether particles, anhydrous ethanol solution and water are placed in a beaker and uniformly mixed and stirred to obtain solution A; step 2: a certain amount of metal salt particles and carbon powder particles are added to solution A and heated in a water bath, and then ammonia water is added and stirred to obtain solution B; step 3: solution B is placed in a reaction kettle for hydrothermal synthesis, the obtained crystalline substance is washed with deionized water for multiple times, and after filtration, the crystalline substance is dried and calcined, and after cooling at room temperature, a denitration catalyst is obtained. A denitration catalyst prepared by the above preparation method is also provided. The denitration catalyst has good low-temperature activity for NH3-SCR reaction, and has high nitrogen selectivity and water resistance and sulfur resistance.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification technology, and in particular to a denitrification catalyst and its preparation method. Background Technology

[0002] Among various NOx control technologies, ammonia selective catalytic reduction (NH3-SCR) denitrification technology is widely used for the purification of NOx from industrial stationary sources. Its reaction equations mainly include standard SCR reactions and fast SCR reactions:

[0003] Standard SCR reactions: 4NH3 + 4NO + O2 → 4N2 + 6H2O; 4NH3 + 2NO2 + O2 → 3N2 + 6H2O;

[0004] Fast SCR reaction: 4NH3 + 2NO + 2NO2 → 4N2 + 6H2O.

[0005] The key to this technology lies in catalytic reduction, specifically the application of the catalyst. Currently, vanadium-based catalysts are used in most steel and coking industries for catalytic reduction, due to their low cost, simple preparation, good denitrification performance, and high resistance. Traditional NH3-SCR processes have high investment and operating costs and often employ high-dust zones. Although soot blowing cleaning processes are used, dust and various metal substances still exist in the treated gas, which not only damage the catalyst structure but also lead to catalyst poisoning and deactivation. The regeneration cost of deactivated catalysts is considerable. In non-power industries, such as steel and coking, flue gas temperatures are mostly low (100℃~250℃), making it impossible to remove NOx from flue gas using traditional denitrification processes. Therefore, low-temperature selective catalytic reduction (LTCR) technology has emerged. LTCR technology performs denitrification after dust removal and desulfurization processes, thus avoiding the corrosive damage of dust to the catalyst. However, the high activation temperature window of traditional vanadium-based catalysts in denitrification processes makes them unsuitable for this technology. Therefore, there is an urgent need to develop catalysts with good denitrification performance under low-temperature conditions.

[0006] Currently, manganese oxide catalysts have achieved excellent catalytic activity in low-temperature denitrification, but they are highly sensitive to the presence of SO2 and H2O in flue gas and exhibit low N2 selectivity. Therefore, developing catalysts with both good low-temperature activity and high resistance to water and sulfur is crucial for the NH3-SCR reaction. Summary of the Invention

[0007] This invention aims to provide a denitrification catalyst and its preparation method. The denitrification catalyst has good low-temperature activity for the NH3-SCR reaction and high water and sulfur resistance.

[0008] This invention provides a method for preparing a denitrification catalyst, comprising:

[0009] Step 1: Take a certain amount of polyether particles, anhydrous ethanol solution and water and put them in a beaker. Mix and stir until homogeneous to obtain solution A;

[0010] Step 2: Add a certain amount of metal salt particles and carbon powder particles to solution A and heat in a water bath, then add ammonia water and stir to obtain solution B;

[0011] Step 3: Place solution B in a reaction vessel for hydrothermal synthesis, wash the obtained crystalline substance multiple times with deionized water, filter, dry and calcine the crystalline substance, and cool it at room temperature to obtain the denitrification catalyst.

[0012] Furthermore, the preparation method is a combined approach of water bath precipitation coupled with hydrothermal synthesis. This method involves in-situ deposition, reaction, and composite growth of multiple components and phases.

[0013] Furthermore, the synthesized denitration catalyst has a petal-like layered structure formed by the interaction of particles and lamellae composed of metal salts, organic carbon, and inorganic carbon.

[0014] Furthermore, the water bath precipitation process facilitates the formation of crystals and lamellar structures, while the hydrothermal synthesis process contributes to crystal growth and aging, as well as the interaction between crystals and lamellar structures.

[0015] Furthermore, the polyether particles in step 1 include one or more of polytetrahydrofuran glycol, polyoxyethylene-polyoxypropylene-polyoxyethylene, and polyoxypropylene glycol. The function of the polyether particles in step 1 includes promoting ion dispersion, forming an organic carbon-based precursor in situ, and promoting the effective binding of metal ions and inorganic carbon powder.

[0016] Furthermore, metal salts serve as key catalytic active sites, carbon powder provides support for inorganic carbon particles while also providing adsorption sites for reactants, and polyether particles, as organic carbon components, provide effective binding between metal salts and inorganic carbon particles, while also playing a role in electron transfer and the transport and activation of adsorption-catalytic sites.

[0017] Furthermore, in step 1, the volume ratio of anhydrous ethanol to water in solution A is controlled between 1:1 and 5:1.

[0018] Furthermore, in step 1, the volume ratio of anhydrous ethanol to water in solution A is controlled between 1:1 and 3:1.

[0019] Furthermore, the metal salt particles in step 2 include one or more of manganese, cobalt, iron, nickel, and copper, and the metal salt particles include one or more of nitrates, sulfates, and acetates.

[0020] Furthermore, in step 2, the mass ratio of metal salt particles to carbon powder particles is controlled at 2% to 20%.

[0021] Furthermore, the mass ratio of the metal salt particles to the carbon powder particles in step 2 is controlled at 5% to 15%.

[0022] Furthermore, the water bath heating temperature in step 2 is room temperature to 100℃.

[0023] Furthermore, the water bath heating temperature in step 2 is 40~80℃.

[0024] Furthermore, the amount of ammonia added in step 2 is 5~35mL / g.

[0025] Furthermore, the amount of ammonia added in step 2 is 5~15mL / g.

[0026] Furthermore, the stirring method in step 2 is mechanical stirring or magnetic stirring.

[0027] Furthermore, the hydrothermal synthesis in step 3 takes 8 to 48 hours and takes 120 to 200°C.

[0028] Furthermore, the hydrothermal synthesis in step 3 takes 12 to 36 hours and takes 140 to 180°C.

[0029] The present invention also provides a denitrification catalyst prepared by the above preparation method.

[0030] The advantages of this invention lie in the fact that the carbon powder and layered metal oxide composite denitration catalyst prepared by the combined method of water bath precipitation and hydrothermal synthesis possesses a unique layered morphology, characterized by a large specific surface area, good nanomaterial size effect, strong planar conductivity, and high electronic conductivity. Simultaneously, the composite denitration synthesis of carbon powder and metal oxide catalyst can improve the low-temperature NH3-SCR performance, nitrogen selectivity, and tolerance to SO2 / H2O through the interaction between the metal and carbon powder. Attached Figure Description

[0031] Figure 1 The figure shown is a comparison of the nitrogen oxide conversion rates of the example and the comparative example under test condition 1.

[0032] Figure 2 The figure shown is a comparison of nitrogen selectivity between the example and the comparative example under test condition 1.

[0033] Figure 3 The figure shown is a comparison of the nitrogen oxide conversion rates of the example and the comparative example under test condition 2.

[0034] Figure 4The figure shown is a comparison of the nitrogen oxide conversion rates of the example and the comparative example under test condition 3. Detailed Implementation

[0035] To provide a further understanding of the purpose, structure, features, and functions of the present invention, detailed descriptions are provided below with reference to specific embodiments.

[0036] This invention provides a method for preparing a denitrification catalyst, comprising:

[0037] Step 1: Take a certain amount of polyether particles, anhydrous ethanol solution and water and put them in a beaker. Mix and stir until homogeneous to obtain solution A;

[0038] Step 2: Add a certain amount of metal salt particles and carbon powder particles to solution A and heat in a water bath, then add ammonia water and stir to obtain solution B;

[0039] Step 3: Place solution B in a reaction vessel for hydrothermal synthesis, wash the obtained crystalline substance multiple times with deionized water, filter, dry and calcine the crystalline substance, and cool it at room temperature to obtain the denitrification catalyst.

[0040] The preparation method is a combined approach of water bath precipitation coupled with hydrothermal synthesis. This method involves in-situ deposition, reaction, and composite growth of multiple components and phases.

[0041] The synthesized denitration catalyst has a petal-like layered structure formed by the interaction of particles and lamellae composed of metal salts, organic carbon, and inorganic carbon.

[0042] The water bath precipitation process helps the formation of crystals and lamellar structures, making the precursor a crystal and initially forming a relatively thick lamellar structure. The hydrothermal synthesis process helps the growth and aging of crystals and the interaction between crystals and lamellar structures, giving the denitrification catalyst a special lamellar morphology with large specific surface area, good nanomaterial size effect, strong planar conductivity and strong electronic conductivity.

[0043] The polyether particles in step 1 include one or more of polytetrahydrofuran glycol, polyoxyethylene-polyoxypropylene-polyoxyethylene, and polyoxypropylene glycol. The function of the polyether particles in step 1 includes promoting ion dispersion, forming an organic carbon-based precursor in situ, and promoting the effective binding of metal ions with inorganic carbon powder.

[0044] Metal salts and their contained metal oxides are key catalytic active sites. Carbon powder, as an inorganic carbon particle, provides support and also provides adsorption sites for reactants. Polyether particles, as an organic carbon component, provide effective binding between metal salts and inorganic carbon particles, and also play a role in electron transfer and the transport and activation of adsorption-catalytic sites.

[0045] A major drawback of current denitrification catalysts is the inability to achieve a robust bond between inorganic carbon and metals. For example, in supported catalysts, inorganic carbon and metals are loosely bonded, forming a supported catalyst. In the denitrification catalyst of this application, polyether particles, as the organic carbon component, act as an excellent mediator, providing effective bonding between the metal salt and inorganic carbon particles. This is because polyether particles, as the organic carbon component, can bond with both metals and inorganic carbon particles, thus achieving effective bonding between them. The organic functional groups of the organic carbon component can complex metal ions (linking the metal end), while its own organic C / N / OH sites can effectively connect with C (particles). While achieving effective bonding between the metal salt and inorganic carbon particles, the polyether particles, as the organic carbon component, also play a role in electron transfer and the transport and activation of adsorption-catalytic sites.

[0046] Furthermore, in step 1, the volume ratio of anhydrous ethanol to water in solution A is controlled between 1:1 and 5:1.

[0047] Furthermore, in step 1, the volume ratio of anhydrous ethanol to water in solution A is controlled between 1:1 and 3:1.

[0048] Furthermore, the metal salt particles in step 2 include one or more of manganese, cobalt, iron, nickel, and copper, and the metal salt particles include one or more of nitrates, sulfates, and acetates.

[0049] Furthermore, in step 2, the mass ratio of metal salt particles to carbon powder particles is controlled at 2% to 20%.

[0050] Furthermore, the mass ratio of the metal salt particles to the carbon powder particles in step 2 is controlled at 5% to 15%.

[0051] Furthermore, the water bath heating temperature in step 2 is room temperature to 100℃.

[0052] Furthermore, the water bath heating temperature in step 2 is 40~80℃.

[0053] Furthermore, the amount of ammonia added in step 2 is 5~35mL / g.

[0054] Furthermore, the amount of ammonia added in step 2 is 5~15mL / g.

[0055] Furthermore, the stirring method in step 2 is mechanical stirring or magnetic stirring.

[0056] Furthermore, the hydrothermal synthesis in step 3 takes 8 to 48 hours and takes 120 to 200°C.

[0057] Furthermore, the hydrothermal synthesis in step 3 takes 12 to 36 hours and takes 140 to 180°C.

[0058] The present invention also provides a denitrification catalyst prepared by the above preparation method.

[0059] The advantages of this invention lie in the fact that the carbon powder and layered metal oxide composite denitration catalyst prepared by the combined method of water bath precipitation and hydrothermal synthesis possesses a unique layered morphology, characterized by a large specific surface area, good nanomaterial size effect, strong planar conductivity, and high electronic conductivity. Furthermore, the composite denitration synthesis of carbon powder and metal oxide catalyst can improve the low-temperature NH3-SCR performance and tolerance to SO2 / H2O through the interaction between the metal and carbon powder. Example

[0060] A denitrification catalyst was prepared according to a method for preparing a composite denitrification catalyst of carbon powder and layered metal oxides.

[0061] Step 1: Accurately weigh 0.800g of polyoxyethylene-polyoxypropylene-polyoxyethylene into a beaker, then add 8.000g of anhydrous ethanol into the beaker, add 4.000g of H2O, and stir with a stirrer for 15min to obtain solution A;

[0062] Step 2: Add 0.892g of manganese acetate tetrahydrate (Mn(AC)2·4H2O), 0.529g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O), and 2.000g of carbon powder particles to solution A, heat in a water bath at 60℃ for 2h, then add 10mL / g of ammonia water and mix evenly by mechanical stirring to obtain solution B;

[0063] Step 3: Place solution B in a reaction vessel and perform hydrothermal synthesis at 160℃ for 24h. Wash the obtained crystalline material with deionized water three times, filter it, and dry the obtained crystalline material at 110℃ for 12h. After cooling to room temperature, obtain the catalyst sample, which is defined as Mn(2)Ni(1)Ox-C catalyst.

[0064] Comparative Example

[0065] Following the preparation method of metal oxide denitration catalysts, the denitration catalyst is prepared by omitting the polyether particle and carbon powder composite denitration steps.

[0066] Step 1: Accurately weigh 0.800g of deionized water into a beaker, then add 8.000g of anhydrous ethanol to the beaker, add 4.000g of H2O, and stir with a stirrer for 15 minutes to obtain solution A;

[0067] Step 2: Add 0.892g of manganese acetate tetrahydrate (Mn(AC)2·4H2O) and 0.529g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) to solution A, heat in a water bath at 60℃ for 2h, then add 10mL / g of ammonia water and mix evenly by mechanical stirring to obtain solution B;

[0068] Step 3: Place solution B in a reaction vessel and perform hydrothermal synthesis at 160℃ for 24h. Wash the obtained crystalline material with deionized water three times, filter it, and dry the obtained crystalline material at 110℃ for 12h. After cooling to room temperature, the catalyst sample is obtained and defined as Mn(2)Ni(1)Ox catalyst.

[0069] Test Condition 1

[0070] The catalyst samples prepared in the examples and comparative examples were subjected to SCR activity tests. The simulated gas was free of water and sulfur. The test conditions were as follows: reaction temperature 100~250 ℃, test time of 1 hour at each temperature, gas flow rate 100 mL / min, NO concentration 500 ppm, NH3 concentration 500 ppm, O2 concentration 5%, N2 as the equilibrium gas, and space velocity 30000 h-1.

[0071] Test Condition 2

[0072] The catalyst samples prepared in the examples and comparative examples were subjected to SCR activity tests. The simulated gas was anhydrous and sulfur-containing. The test conditions were: reaction temperature 200℃, reaction time 5 hours, gas flow rate 100 mL / min, NO concentration 500 ppm, NH3 concentration 500 ppm, SO2 concentration 200 ppm, O2 concentration 5%, N2 as the equilibrium gas, and space velocity 30000 h-1.

[0073] Test Condition 3

[0074] The catalyst samples prepared in the examples and comparative examples were subjected to SCR activity tests. The simulated gas contained water and did not contain sulfur. The test conditions were as follows: reaction temperature 200℃, reaction time 5 hours, gas flow rate 100 mL / min, NO concentration 500 ppm, NH3 concentration 500 ppm, H2O volume concentration 10%, O2 concentration 5%, N2 as the equilibrium gas, and space velocity 30000 h-1.

[0075] The nitrogen oxide removal rate and nitrogen selectivity of the catalysts prepared in the examples and comparative examples under different test conditions are shown in Table 1.

[0076] Table 1. SCR denitrification activity and selectivity of the examples and comparative samples under different test conditions (unit: %)

[0077]

[0078] As shown in Table 1, the carbon powder and layered metal oxide composite denitrification Mn prepared in the examples (2) Ni (1) O x The -C catalyst exhibits excellent SCR denitrification activity under anhydrous and sulfur-free conditions (test condition 1), with a nitrogen oxide conversion rate greater than 80% in the 150–250 °C range and a nitrogen selectivity close to or greater than 90% in the 100–200 °C range. Under anhydrous and sulfur-containing conditions (test condition 2), the catalyst still exhibits good sulfur resistance (200 °C, 84%), and the nitrogen selectivity only decreases slightly (200 °C, 78%). Under anhydrous and sulfur-free conditions (test condition 3), the denitrification efficiency of the catalyst remains at 87%, while the nitrogen selectivity increases to 88%.

[0079] Mn prepared by comparison without being combined with toner (2) Ni (1) O x Although the catalyst exhibits high nitrogen selectivity in the medium-low temperature range (100~150℃) under test conditions 1 (anhydrous and sulfur-free), its nitrogen oxide conversion rate is poor. Under test conditions 2 (anhydrous and sulfur-containing), both the nitrogen oxide conversion rate and nitrogen selectivity of the catalyst decrease. Under test conditions 3 (aqueous and sulfur-free), although the nitrogen selectivity of the catalyst recovers, its nitrogen oxide conversion rate remains low.

[0080] The carbon powder and layered metal oxide composite denitration catalyst, prepared via a combined water bath heating and hydrothermal synthesis, exhibits a unique layered morphology, characterized by a large specific surface area, favorable nanomaterial size effect, strong planar conductivity, and high electronic conductivity. Furthermore, the composite denitration synthesis of carbon powder and metal oxide catalysts can improve the low-temperature NH3-SCR performance through the interaction between the metal and carbon powder. The prepared catalyst demonstrates highly efficient selective catalytic reduction (SCR) denitration activity, with the target product exhibiting high nitrogen oxide conversion efficiency and good nitrogen selectivity within the tested temperature range. This overcomes the drawbacks of poor resistance and low selectivity in traditional denitration catalysts, providing a new approach for the development of SCR denitration catalysts.

[0081] In summary, the carbon powder and layered metal oxide composite denitration catalyst prepared in this embodiment exhibits highly efficient selective catalytic reduction (SCR) denitration activity. The target product obtained has high nitrogen oxide conversion efficiency and good nitrogen selectivity within the test temperature range, overcoming the drawbacks of poor resistance and low selectivity of denitration catalysts, and providing a new approach for the development of SCR denitration catalysts.

[0082] The present invention has been described in the above-described embodiments; however, these embodiments are merely examples for implementing the present invention. It must be noted that the disclosed embodiments do not limit the scope of the present invention. Conversely, any modifications and refinements made without departing from the spirit and scope of the present invention are within the scope of patent protection of the present invention.

Claims

1. A method for producing a denitration catalyst, characterized by, The application relates to a preparation method of a denitration catalyst. Step 1: a certain amount of polyether particles, anhydrous ethanol and water are mixed in a beaker to obtain solution A; Step 2: a certain amount of metal salt particles and carbon powder particles are added to solution A and heated in a water bath, then ammonia water is added and stirred to obtain solution B; Step 3: solution B is placed in a reaction kettle for hydrothermal synthesis, the obtained crystalline substance is washed with deionized water for multiple times, the crystalline substance is dried and calcined after filtration, and the denitration catalyst is obtained after cooling at room temperature; The preparation method is a combined method of water bath precipitation and hydrothermal synthesis, and involves the processes of in-situ deposition, reaction and compounding of multiple components and multiple phases; The synthesized denitration catalyst is a petal sheet structure formed by the alternation of particles and sheets composed of metal salt, organic carbon and inorganic carbon, The water bath precipitation helps the formation of crystals and sheet structures, and the hydrothermal synthesis helps the growth and aging of the crystals and the alternation of the crystals and the sheet structures, The metal salt is a key catalytic active site, the carbon powder provides carrier support as inorganic carbon particles and also provides adsorption sites for reactants, the polyether particles provide effective combination between the metal salt and the inorganic carbon particles and also play the roles of electron transmission and adsorption-catalytic site transmission and activation, The polyether particles in step 1 include one or more of polytetrahydrofuran diol, polyoxyethylene-polyoxypropylene-polyoxyethylene and polypropylene glycol, and the polyether particles in step 1 have the functions of promoting ion dispersion, in-situ forming an organic carbon-based precursor and promoting effective combination of metal ions and inorganic carbon powder.

2. The method for producing a de-NOx catalyst according to claim 1, characterized by, The volume ratio of anhydrous ethanol to water in solution A in step 1 is controlled to be 1:1-5:

1.

3. The method for producing a de-NOx catalyst according to Claim 1, characterized by, The metal in the metal salt particles in step 2 includes one or more of manganese, cobalt, iron, nickel and copper, and the metal salt particles include one or more of nitrate, sulfate and acetate.

4. The method for producing a de-NOx catalyst according to Claim 1, characterized by, The mass ratio of the metal salt particles to the carbon powder particles in step 2 is controlled to be 2%-20%.

5. The method of producing a de-NOx catalyst according to claim 1, wherein The water bath heating temperature in step 2 is room temperature-100 DEG C.

6. The method of producing a de-NOx catalyst according to claim 1, wherein The ammonia water addition amount in step 2 is 5-35 mL / g.

7. The method of producing a de-NOx catalyst according to claim 1, wherein The synthesis time of the hydrothermal synthesis in step 3 is 8-48 h, and the synthesis temperature of the hydrothermal synthesis is 120-200 DEG C.

8. The method of producing a de-NOx catalyst according to claim 7, wherein The synthesis time of the hydrothermal synthesis in step 3 is 12-36 h, and the synthesis temperature of the hydrothermal synthesis is 140-180 DEG C. 9.A denitration catalyst prepared by using the preparation method of the denitration catalyst according to any one of claims 1-8.

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