A method for the selective catalytic reduction of NO by ammonia x Catalysts, their preparation methods and applications

Abstract

This invention relates to a method for the selective catalytic reduction of NO by ammonia. x This invention relates to a catalyst, its preparation method, and its application, belonging to the field of environmental catalysis and air pollution control technology. The catalyst comprises a support, a main active component, and a modifying agent. The support is selected from SAPO-18 molecular sieve, the main active component is selected from Cu, and the modifying agent is selected from Zr. The space velocity is 88,000 h⁻¹. ‑1 At that time, the ZrCu-SAPO-18 molecular sieve catalyst, within the temperature range of 225–450℃, produced NO x The conversion rate reached over 90%; after hydrothermal treatment at 750℃ for 12 hours, NO was reduced within the range of 175–400℃. x The conversion rate remains above 90%. The catalyst of this invention can be used to remove NO from diesel vehicle exhaust and stationary source flue gas. x Highly efficient removal.

Description

Technical Field

[0001] This invention relates to a method for the selective catalytic reduction of NO by ammonia. x Catalysts, their preparation methods, and applications are applicable to NO in diesel vehicle exhaust and stationary source flue gas. x The catalytic removal belongs to the field of environmental catalysis and air pollution control technology. Background Technology

[0002] NO x As a major air pollutant, NO poses a serious threat to environmental quality and human health. Therefore, NO under oxygen-enriched conditions... x Controlling NO has become a research hotspot in the field of atmospheric environmental protection technology. Currently, ammonia selective catalytic reduction (NH3-SCR) is a method for controlling NO under oxygen-rich conditions. x An effective means of removal. For NH3-SCR denitrification technology, traditional vanadium-based catalysts are effective in removing NO3 emissions from coal-fired power plants. x While widely used in NOx control, vanadium-based catalysts have a narrow temperature window (300℃-400℃) and contain the biotoxic active component V₂O₅. Given the low exhaust temperature and wide temperature fluctuation range of diesel vehicles, the narrow temperature window of vanadium-based catalysts cannot effectively control NOx emissions from diesel vehicles. x Highly efficient removal of emissions. Therefore, developing SCR catalysts with a wider active temperature window is of great significance for the purification of diesel vehicle exhaust.

[0003] Molecular sieve catalysts have been discovered and are increasingly widely studied and applied due to their unique pore structure, wide reaction activity window, and non-toxicity. In recent years, CHA-type molecular sieves (SSZ-13 and SAPO-34) have attracted considerable attention due to their excellent SCR activity and good hydrothermal stability. However, Cu-CHA molecular sieves still face deactivation issues at high temperatures (850℃). With increasingly stringent diesel vehicle emission regulations, researchers are dedicated to developing other types of molecular sieves, and AEI-type molecular sieve catalysts (SAPO-18 and SSZ-39), which have a structure very similar to CHA, are increasingly attracting researchers' attention.

[0004] This invention prepares a ZrCu-SAPO-18 molecular sieve catalyst that exhibits good catalytic activity, excellent hydrothermal stability, and resistance to sulfur poisoning in NH3-SCR denitrification over a wide temperature range. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the selective catalytic reduction of NO by ammonia. x The catalyst, its preparation method, and its application are described. The preparation method is simple, and it exhibits excellent performance in NH3-SCR denitrification. Through the synergistic effect between Zr and Cu in the catalyst, not only is the active Cu in the catalyst enhanced...2+ The increased number of sites and acidic sites on the catalyst surface result in excellent NH3-SCR denitrification activity, hydrothermal stability, and resistance to sulfur poisoning, thus achieving a highly efficient NO removal catalyst over a wide temperature window. x Catalyst.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a method for the selective catalytic reduction of NO by ammonia. x The catalyst comprises a support, a main active component, and a modifying agent. The catalyst uses SAPO-18 small-pore molecular sieve as the support, Cu as the main active component, and Zr as the modifying agent. Its composition is expressed as ZrCu-SAPO-18. Based on the mass of the support as 100%, the mass percentage of Cu is 0.5-2%, and the mass percentage of Zr is 0.02-0.2%.

[0008] In a second aspect, the present invention provides a method for preparing the catalyst as described in the first aspect, the method comprising the following steps:

[0009] (1) Using N-N diisopropylethylamine (C8H) 19 N) was used as a template agent to prepare a synthesis solution, which was then subjected to hydrothermal reaction, solid-liquid separation, washing, drying, and calcination at 450-550℃ to obtain small-pore molecular sieve SAPO-18.

[0010] (2) The small-pore molecular sieve SAPO-18 from step (1) was treated with ammonium nitrate solution to obtain NH4-SAPO-18;

[0011] (3) Place NH4-SAPO-18 in a copper nitrate solution for at least two ion exchanges, wash, dry, and calcine at 450-550℃ to obtain Cu-SAPO-18;

[0012] (4) Cu-SAPO-18 was impregnated in zirconium nitrate solution, dried, and calcined at 450-550℃ to obtain ZrCu-SAPO-18 catalyst.

[0013] Preferably, the molar composition of the synthesis solution in step (1) is (1.4~1.8)NN diisopropylethylamine:1Al2O3:

[0014] (0.85~0.95)P2O5:(0.95~1.05)SiO2:(40~60)H2O; for example: 1.6DIEA:1Al2O3:0.9P2O5:

[0015] 1.0SiO2:50H2O, etc.

[0016] Preferably, the solid-liquid separation and washing in step (1) are performed 5 to 8 times.

[0017] Preferably, the solid-liquid separation method in step (1) is selected from centrifugation.

[0018] Preferably, the drying method in step (1) is to dry at 90-110°C for 12-24 hours.

[0019] Preferably, the roasting time in step (1) is 4 to 8 hours.

[0020] Preferably, the concentration of the ammonium nitrate solution in step (2) is 0.9 mol / L to 1.1 mol / L, for example, 0.95 mol / L.

[0021] 1.0 mol / L, 1.1 mol / L, etc.

[0022] Preferably, the method of treating small-pore molecular sieve SAPO-18 with ammonium nitrate solution in step (2) includes: adding small-pore molecular sieve SAPO-18 to ammonium nitrate solution, stirring at 60-80°C for 5-10 hours, separating the solid and liquid of the product and washing it with water, and drying it at 90-110°C for 12-24 hours.

[0023] Preferably, the number of ion exchanges in step (3) is selected from 2 times.

[0024] Preferably, the duration of each ion exchange is selected from 6h to 10h.

[0025] Preferably, the temperature for ion exchange is selected from 70℃ to 85℃.

[0026] Preferably, the calcination time in step (3) is 4 to 8 hours.

[0027] Preferably, the concentration of the copper nitrate solution in step (3) is selected from 0.05 to 0.2 mol / L.

[0028] Preferably, the ion exchange method in step (3) includes: adding the NH4-SAPO-18 obtained in step (2) to a copper nitrate solution for ion exchange, followed by solid-liquid separation, washing the product with water, and then heating at 90–110°C.

[0029] Dry for 12–24 hours, then perform a second ion exchange.

[0030] Preferably, the zirconium mass fraction in the zirconium nitrate solution in step (4) is 0.02–0.2 wt%.

[0031] Preferably, the impregnation method in step (4) includes: adding the Cu-SAPO-18 obtained in step (3) into a zirconium nitrate solution and stirring for 4 to 8 hours. The impregnation temperature is preferably room temperature, and more preferably 20°C to 35°C.

[0032] Preferably, the drying temperature in step (4) is 110–130°C, and the drying time is 12–24 hours.

[0033] Preferably, the roasting time in step (4) is 4 to 8 hours.

[0034] Preferably,

[0035] The method includes the following steps in sequence:

[0036] (a) Prepare a 0.1 mol / L ammonium nitrate solution and a 0.05–0.2 mol / L copper nitrate (copper acetate) solution;

[0037] (b) with N-N diisopropylethylamine (C8H) 19 SAPO-18 molecular sieve was synthesized by hydrothermal method using N as template agent. The molar composition of the synthesis solution was 1.6DIEA:1Al2O3:0.9P2O5:1.0SiO2:50H2O.

[0038] (c) Take the reaction solution obtained in step (2) and centrifuge and wash it 5 to 8 times. Dry it at 100°C for 12 to 24 hours, and then calcine it in a muffle furnace at 450 to 550°C for 4 to 8 hours to obtain SAPO-18 molecular sieve catalyst.

[0039] (d) The SAPO-18 molecular sieve obtained in step (3) was added to a 0.1 mol / L ammonium nitrate solution and stirred at 60-80°C for 5-10 hours. The product was filtered and washed with deionized water and dried at 100°C for 12-24 hours to obtain the NH4-SAPO-18 catalyst.

[0040] (e) The NH4-SAPO-18 catalyst sample obtained in step (4) was added to a 0.05-0.2 mol / L copper nitrate solution and ion-exchanged at 80°C for 8 hours. The product was filtered and washed with deionized water, dried at 100°C for 12-24 hours, and then ion-exchanged a second time at the same ratio, washed and dried. The product was then calcined in a muffle furnace at 450-550°C for 4-8 hours to obtain the Cu-SAPO-18 catalyst.

[0041] (f) The sample obtained in step (5) is added to a zirconium nitrate solution with a zirconium mass fraction of 0.02 to 0.20 wt%, stirred at room temperature for 4 to 8 hours, and the slurry is dried at 120°C for 12 to 24 hours to obtain a dried sample; the sample is placed in a muffle furnace and calcined at 450 to 550°C for 4 to 8 hours to obtain a ZrCu-SAPO-18 catalyst.

[0042] The catalyst of this invention, after hydrothermal treatment at 750°C for 12 hours, exhibits NO reduction within the temperature range of 175–400°C. x The conversion rate can still reach over 90%.

[0043] Compared with the prior art, the present invention has the following advantages and outstanding effects: Due to the synergistic effect between Cu and Zr, the ZrCu-SAPO-18 molecular sieve catalyst improves the denitrification performance of the catalyst and broadens the active temperature window of the catalyst. In the range of 225 to 450℃, the purification efficiency of nitrogen oxides reaches more than 90%. At the same time, the ZrCu-SAPO-18 molecular sieve catalyst has excellent hydrothermal stability and resistance to sulfur poisoning. After high-temperature hydrothermal aging treatment, the activity of ZrCu-SAPO-18 catalyst not only does not decrease, but is significantly improved. Attached Figure Description

[0044] Figure 1 The effect of SO2 on the activity of 0.64% Cu-SAPO-18 and 0.05% Zr-0.64% Cu-SAPO-18 catalysts is shown.

[0045] Specific implementation methods

[0046] The technical solution of the present invention will be further described below with reference to the embodiments:

[0047] Example 1: Preparation of 0.02% Zr-0.64% Cu-SAPO-18 catalyst

[0048] a) Using N-N diisopropylethylamine (C8H) 19 SAPO-18 molecular sieves were synthesized via a hydrothermal method using N as a template agent. The molar composition of the synthesis solution was 1.6DIEA:1Al2O3:0.9P2O5:1.0SiO2:50H2O. The specific steps of the hydrothermal synthesis method were as follows: pseudoboehmite was dissolved in a certain amount of deionized water, followed by the dropwise addition of phosphoric acid, stirring for 1 hour, then an appropriate amount of silica sol was added, and stirring was continued for another 1 hour. Finally, the template agent C8H... 19 N was added dropwise to the mixed solution and stirred for 1 hour. The mixture was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and crystallized at 180°C for 7 days. After cooling, it was filtered, washed by centrifugation, dried at 100°C for 12 hours, and calcined at 550°C for 6 hours to obtain SAPO-18 molecular sieve.

[0049] b) Add SAPO-18 molecular sieve to 0.1 mol / L ammonium nitrate solution (solid-liquid ratio of 1 / 50), stir at 80°C for 8 hours, filter and wash the product with deionized water, and dry at 100°C for 12 hours to obtain NH4-SAPO-18 catalyst.

[0050] c) The NH4-SAPO-18 catalyst sample was added to a 0.05 mol / L copper nitrate solution (solid-liquid ratio 1 / 100), and ion exchange was performed at 80 °C for 8 hours. The product was filtered and washed with deionized water, dried at 100 °C for 12 hours, and then subjected to a second ion exchange at the same ratio, followed by washing and drying. The product was then calcined in a muffle furnace at 550 °C for 6 hours to obtain a 0.64% Cu-SAPO-18 catalyst.

[0051] d) Weigh 0.001g Zr(NO3)4·5H2O and dissolve it in 10mL of deionized water. Stir thoroughly and then add 1g of the 0.64% Cu-SAPO-18 powder obtained in step c). Stir at room temperature for 4 hours and dry the resulting slurry at 120℃ for 12 hours. Then, calcine it in a muffle furnace at 550℃ for 6 hours to obtain the 0.02% Zr-0.64% Cu-SAPO-18 catalyst.

[0052] Example 2: Preparation of 0.05% Zr-0.64% Cu-SAPO-18 catalyst

[0053] a) Using N-N diisopropylethylamine (C8H) 19 SAPO-18 molecular sieves were synthesized via a hydrothermal method using N as a template agent. The molar composition of the synthesis solution was 1.6DIEA:1Al2O3:0.9P2O5:1.0SiO2:50H2O. The specific steps of the hydrothermal synthesis method were as follows: pseudoboehmite was dissolved in a certain amount of deionized water, followed by the dropwise addition of phosphoric acid, stirring for 1 hour, then an appropriate amount of silica sol was added, and stirring was continued for another 1 hour. Finally, the template agent C8H... 19 N was added dropwise to the mixed solution and stirred for 1 hour. The mixture was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and crystallized at 180°C for 7 days. After cooling, it was filtered, washed by centrifugation, dried at 100°C for 12 hours, and calcined at 550°C for 6 hours to obtain SAPO-18 molecular sieve.

[0054] b) Add SAPO-18 molecular sieve to 0.1 mol / L ammonium nitrate solution (solid-liquid ratio of 1 / 50), stir at 80°C for 8 hours, filter and wash the product with deionized water, and dry at 100°C for 12 hours to obtain NH4-SAPO-18 catalyst.

[0055] c) The NH4-SAPO-18 catalyst sample was added to a 0.05 mol / L copper nitrate solution (solid-liquid ratio 1 / 100), and ion exchange was performed at 80 °C for 8 hours. The product was filtered and washed with deionized water, dried at 100 °C for 12 hours, and then subjected to a second ion exchange at the same ratio, followed by washing and drying. The product was then calcined in a muffle furnace at 550 °C for 6 hours to obtain a 0.64% Cu-SAPO-18 catalyst.

[0056] d) Weigh 0.0024g Zr(NO3)4·5H2O and dissolve it in 10mL of deionized water. Stir thoroughly and then add 1g of the 0.64% Cu-SAPO-18 powder obtained in step c). Stir at room temperature for 4 hours and dry the resulting slurry at 120℃ for 12 hours. Then, calcine it in a muffle furnace at 550℃ for 6 hours to obtain the 0.05% Zr-0.64% Cu-SAPO-18 catalyst.

[0057] Example 3: Preparation of 0.2% Zr-0.64% Cu-SAPO-18 catalyst

[0058] a) Using N-N diisopropylethylamine (C8H) 19 SAPO-18 molecular sieves were synthesized via a hydrothermal method using N as a template agent. The molar composition of the synthesis solution was 1.6DIEA:1Al2O3:0.9P2O5:1.0SiO2:50H2O. The specific steps of the hydrothermal synthesis method were as follows: pseudoboehmite was dissolved in a certain amount of deionized water, followed by the dropwise addition of phosphoric acid, stirring for 1 hour, then an appropriate amount of silica sol was added, and stirring was continued for another 1 hour. Finally, the template agent C8H... 19 N was added dropwise to the mixed solution and stirred for 1 hour. The mixture was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and crystallized at 180°C for 7 days. After cooling, it was filtered, washed by centrifugation, dried at 100°C for 12 hours, and calcined at 550°C for 6 hours to obtain SAPO-18 molecular sieve.

[0059] b) Add SAPO-18 molecular sieve to 0.1 mol / L ammonium nitrate solution (solid-liquid ratio of 1 / 50), stir at 80°C for 8 hours, filter and wash the product with deionized water, and dry at 100°C for 12 hours to obtain NH4-SAPO-18 catalyst.

[0060] c) The NH4-SAPO-18 catalyst sample was added to a 0.05 mol / L copper nitrate solution (solid-liquid ratio 1 / 100), and ion exchange was performed at 80 °C for 8 hours. The product was filtered and washed with deionized water, dried at 100 °C for 12 hours, and then subjected to a second ion exchange at the same ratio, followed by washing and drying. The product was then calcined in a muffle furnace at 550 °C for 6 hours to obtain a 0.64% Cu-SAPO-18 catalyst.

[0061] d) Weigh 0.0094g Zr(NO3)4·5H2O and dissolve it in 10mL of deionized water. Stir thoroughly, then add 1g of Cu obtained in step c). 0.64 -SAPO-18 powder was stirred at room temperature for 4 hours, and the resulting slurry was dried at 120°C for 12 hours. Then, it was placed in a muffle furnace and calcined at 550°C for 6 hours to obtain a 0.2%Zr-0.64%Cu-SAPO-18 catalyst.

[0062] Example 4: Preparation of 0.05% Zr-0.5% Cu-SAPO-18 catalyst

[0063] a) Using N-N diisopropylethylamine (C8H) 19 SAPO-18 molecular sieves were synthesized via a hydrothermal method using N as a template agent. The molar composition of the synthesis solution was 1.6DIEA:1Al2O3:0.9P2O5:1.0SiO2:50H2O. The specific steps of the hydrothermal synthesis method were as follows: pseudoboehmite was dissolved in a certain amount of deionized water, followed by the dropwise addition of phosphoric acid, stirring for 1 hour, then an appropriate amount of silica sol was added, and stirring was continued for another 1 hour. Finally, the template agent C8H... 19 N was added dropwise to the mixed solution and stirred for 1 hour. The mixture was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and crystallized at 180°C for 7 days. After cooling, it was filtered, washed by centrifugation, dried at 100°C for 12 hours, and calcined at 550°C for 6 hours to obtain SAPO-18 molecular sieve.

[0064] b) Add SAPO-18 molecular sieve to 0.1 mol / L ammonium nitrate solution (solid-liquid ratio of 1 / 50), stir at 80°C for 8 hours, filter and wash the product with deionized water, and dry at 100°C for 12 hours to obtain NH4-SAPO-18 catalyst.

[0065] c) The NH4-SAPO-18 catalyst sample was added to a 0.05 mol / L copper nitrate solution (solid-liquid ratio 1 / 100), and ion exchange was performed at 80 °C for 8 hours. The product was then filtered and washed with deionized water and dried at 100 °C for 12 hours. The product was then calcined in a muffle furnace at 550 °C for 6 hours to obtain a 0.5% Cu-SAPO-18 catalyst.

[0066] d) Weigh 0.0024g Zr(NO3)4·5H2O and dissolve it in 10mL of deionized water. Stir thoroughly, then add 1g of Cu obtained in step c). 0.5-SAPO-18 powder was stirred at room temperature for 4 hours, and the resulting slurry was dried at 120°C for 12 hours. Then, it was placed in a muffle furnace and calcined at 550°C for 6 hours to obtain a 0.05%Zr-0.5%Cu-SAPO-18 catalyst.

[0067] Example 5: Preparation of 0.05% Zr-2% Cu-SAPO-18 catalyst

[0068] a) Using N-N diisopropylethylamine (C8H) 19 SAPO-18 molecular sieves were synthesized via a hydrothermal method using N as a template agent. The molar composition of the synthesis solution was 1.6DIEA:1Al2O3:0.9P2O5:1.0SiO2:50H2O. The specific steps of the hydrothermal synthesis method were as follows: pseudoboehmite was dissolved in a certain amount of deionized water, followed by the dropwise addition of phosphoric acid, stirring for 1 hour, then an appropriate amount of silica sol was added, and stirring was continued for another 1 hour. Finally, the template agent C8H... 19 N was added dropwise to the mixed solution and stirred for 1 hour. The mixture was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and crystallized at 180°C for 7 days. After cooling, it was filtered, washed by centrifugation, dried at 100°C for 12 hours, and calcined at 550°C for 6 hours to obtain SAPO-18 molecular sieve.

[0069] b) Add SAPO-18 molecular sieve to 0.1 mol / L ammonium nitrate solution (solid-liquid ratio of 1 / 50), stir at 80°C for 8 hours, filter and wash the product with deionized water, and dry at 100°C for 12 hours to obtain NH4-SAPO-18 catalyst.

[0070] c) The NH4-SAPO-18 catalyst sample was added to a 0.2 mol / L copper nitrate solution (solid-liquid ratio 1 / 100), and ion exchange was performed at 80 °C for 8 hours. The product was then filtered and washed with deionized water and dried at 100 °C for 12 hours. The product was then calcined in a muffle furnace at 550 °C for 6 hours to obtain a 2% Cu-SAPO-18 catalyst.

[0071] d) Weigh 0.0024g Zr(NO3)4·5H2O and dissolve it in 10mL of deionized water. Stir thoroughly and then add 1g of 2% Cu-SAPO-18 powder from step c). Stir at room temperature for 4 hours. Dry the resulting slurry at 120℃ for 12 hours and then calcine it in a muffle furnace at 550℃ for 6 hours to obtain 0.05% Zr-2% Cu-SAPO-18 catalyst.

[0072] Example 6 (Reference): Preparation of 0.64% Cu-SAPO-18 catalyst

[0073] a) Using N-N diisopropylethylamine (C8H)19 SAPO-18 molecular sieves were synthesized via a hydrothermal method using N as a template agent. The molar composition of the synthesis solution was 1.6DIEA:1Al2O3:0.9P2O5:1.0SiO2:50H2O. The specific steps of the hydrothermal synthesis method were as follows: pseudoboehmite was dissolved in a certain amount of deionized water, followed by the dropwise addition of phosphoric acid, stirring for 1 hour, then an appropriate amount of silica sol was added, and stirring was continued for another 1 hour. Finally, the template agent C8H... 19 N was added dropwise to the mixed solution and stirred for 1 hour. The mixture was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and crystallized at 180°C for 7 days. After cooling, it was filtered, washed by centrifugation, dried at 100°C for 12 hours, and calcined at 550°C for 6 hours to obtain SAPO-18 molecular sieve.

[0074] b) Add SAPO-18 molecular sieve to 0.1 mol / L ammonium nitrate solution (solid-liquid ratio of 1 / 50), stir at 80°C for 8 hours, filter and wash the product with deionized water, and dry at 100°C for 12 hours to obtain NH4-SAPO-18 catalyst.

[0075] c) The NH4-SAPO-18 catalyst sample was added to a 0.05 mol / L copper nitrate solution (solid-liquid ratio 1 / 100), and ion exchange was performed at 80 °C for 8 hours. The product was filtered and washed with deionized water, dried at 100 °C for 12 hours, and then subjected to a second ion exchange at the same ratio, followed by washing and drying. The product was then calcined in a muffle furnace at 550 °C for 6 hours to obtain a 0.64% Cu-SAPO-18 catalyst.

[0076] Example 7: The catalyst was prepared using the same method as in Example 1. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃, and NO is evaluated at different temperatures. x The conversion rate is shown in Table 1.

[0077] Example 8: The catalyst was prepared using the same method as in Example 2. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃, and NO is evaluated at different temperatures.x The conversion rate is shown in Table 1.

[0078] Example 9: The catalyst was prepared using the same method as in Example 3. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃, and NO is evaluated at different temperatures. x The conversion rate is shown in Table 1.

[0079] Example 10: The catalyst was prepared using the same method as in Example 4. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃, and NO is evaluated at different temperatures. x The conversion rate is shown in Table 1.

[0080] Example 11: The catalyst was prepared using the same method as in Example 5. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃, and NO is evaluated at different temperatures. x The conversion rate is shown in Table 1.

[0081] Table 1. Activity evaluation results of copper-zirconium bimetallic supported molecular sieves and reference catalysts

[0082]

[0083] Example 12: The catalyst was prepared using the same method as in Example 6. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃, and NO is evaluated at different temperatures.x The conversion rate is shown in Table 1.

[0084] Example 13: The catalyst was prepared using the same method as in Example 2. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, 5 vol% H2O, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / s. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The catalyst was hydrothermally treated at 750℃ for 12 hours. The activity evaluation temperature range was 150–500℃, and NO was measured at different temperatures. x The conversion rate is shown in Table 1.

[0085] Example 14: The catalyst was prepared using the same method as in Example 6. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, 5 vol% H2O, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The catalyst was hydrothermally treated at 750℃ for 12 hours. The activity evaluation temperature range was 150–500℃, and NO was measured at different temperatures. x The conversion rate is shown in Table 1.

[0086] Example 15: The catalyst was prepared using the same method as in Example 2. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, 50 ppm SO2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃, and NO is evaluated at different temperatures. x The conversion rate is shown in Table 1.

[0087] Example 16: The catalyst preparation method was the same as in Example 6. 0.12 g of catalyst was loaded into a fixed-bed reactor. The reaction conditions were: 500 ppm NO, 500 ppm NH3, 5% O2, 50 ppm SO2, with N2 as the equilibrium gas. The gas flow rate was 300 cm³ / h. 3 ·min -1 The gas space velocity (GHSV) is 88,000 h⁻¹. -1 The activity evaluation temperature range is 150–500℃. Its resistance to SO2 poisoning is as follows: Figure 1 As shown.

Claims

1. A method for selective catalytic reduction of NO by ammonia x Catalysts in diesel vehicle exhaust and stationary source NO x Its application in catalytic removal is characterized by: The catalyst comprises a support, a main active component, and a modifying agent. The support of the catalyst is a small-pore molecular sieve SAPO-18, Cu is the main active component, and Zr is the modifying agent. Its composition is expressed as ZrCu-SAPO-18. Based on the mass of the support as 100%, the mass percentage of Cu is 0.5-0.64%, and the mass percentage of Zr is 0.05%. The small-pore molecular sieve SAPO-18 is prepared by the following method, specifically including: A synthesis solution was prepared using N,N-diisopropylethylamine as a template agent, followed by hydrothermal reaction, solid-liquid separation, washing, drying, and calcination at 450–550 °C to obtain small-pore molecular sieve SAPO-18. The molar composition of the synthesis solution is (1.4–1.8) N,N-diisopropylethylamine: 1Al₂O₃: (0.85~0.95)P2O5: (0.95~1.05)SiO2: (40~60)H2O.

2. The application according to claim 1, characterized in that: the method for preparing the catalyst includes the following steps: (1) A synthesis solution was prepared using N,N-diisopropylethylamine as a template agent, followed by hydrothermal reaction, solid-liquid separation, washing, drying, and calcination at 450-550℃ to obtain small-pore molecular sieve SAPO-18. (2) The small-pore molecular sieve SAPO-18 obtained in step (1) was treated with ammonium nitrate solution to obtain NH4-SAPO-18; (3) Place NH4-SAPO-18 in a copper nitrate solution for at least two ion exchanges, wash, dry, and calcine at 450-550℃ to obtain Cu-SAPO-18; (4) Cu-SAPO-18 was impregnated in zirconium nitrate solution, dried, and calcined at 450-550℃ to obtain ZrCu-SAPO-18 catalyst.

3. The application according to claim 2, characterized in that: In step (1), the solid-liquid separation and washing are performed 5 to 8 times.

4. The application according to claim 2, characterized in that: The solid-liquid separation method in step (1) is centrifugation.

5. The application according to claim 2, characterized in that: The drying method in step (1) is to dry at 90-110℃ for 12-24 hours.

6. The application according to claim 2, characterized in that: The roasting time in step (1) is 4 to 8 hours.

7. The application according to claim 2, characterized in that: In step (2), the concentration of ammonium nitrate solution is 0.9 mol / L to 1.1 mol / L.

8. According to claim 2, the method of treating the small-pore molecular sieve SAPO-18 with ammonium nitrate solution in step (2) includes: SAPO-18 small-pore molecular sieve was added to an ammonium nitrate solution and stirred at 60–80°C for 5–10 hours. The product was then separated into solid and liquid phases, washed with water, and dried at 90–110°C for 12–24 hours.

9. The application according to claim 2, characterized in that: The number of ion exchanges in step (3) is 2.

10. The application according to claim 2, characterized in that: Each ion exchange lasts for 6 to 10 hours.

11. The application according to claim 2, characterized in that: The temperature for ion exchange is 70℃~85℃.

12. The application according to claim 2, characterized in that: The calcination time in step (3) is 4 to 8 hours.

13. The application according to claim 2, characterized in that: In step (3), the concentration of the copper nitrate solution is 0.05–0.2 mol / L.

14. The application according to claim 2, characterized in that: The ion exchange method in step (3) includes: adding the NH4-SAPO-18 obtained in step (2) into a copper nitrate solution for ion exchange, followed by solid-liquid separation, washing the product with water, drying it at 90-110°C for 12-24 hours, and then performing a second ion exchange.

15. The application according to claim 2, characterized in that: The zirconium mass fraction in the zirconium nitrate solution in step (4) is 0.02–0.2 wt%.

16. The application according to claim 2, characterized in that, The impregnation method in step (4) includes: adding the Cu-SAPO-18 obtained in step (3) into a zirconium nitrate solution, stirring for 4 to 8 hours, and the impregnation temperature is room temperature.

17. The application according to claim 2, characterized in that, The drying temperature in step (4) is 110-130℃; the drying time is 12-24 hours.

18. The application according to claim 2, characterized in that, The roasting time in step (4) is 4 to 8 hours.

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