A rare earth cerium-based coupling Zr3SO9 superacid wide-temperature denitration catalyst, a preparation method and application thereof

Abstract

The application discloses a preparation method of a rare earth cerium-based coupling Zr3SO9 superacid nanometer catalyst and application of the catalyst in flue gas denitration. The method comprises the following steps: mixing a certain amount of ZrOCl2 with H2SO4, and then performing hydrothermal reaction at 240 DEG C for 72 hours to obtain Zr3SO9 superacid crystal material. After Zr3SO9 and Ce(NO3)3.6H2O are mixed and ground, the mixture is placed in a muffle furnace to be calcined to obtain CeO2 / Zr3SO9. The preparation method has the advantages that the prepared catalyst has a wide active temperature window, excellent sulfur resistance and water resistance, the required raw material resources are rich, the preparation process is simple and environment-friendly, and the catalyst has a potential industrial application prospect.

Description

Technical Field

[0001] This invention relates to a rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst, its preparation method and application, belonging to the technical field of wide-temperature denitration catalysts. Background Technology

[0002] With rapid economic and social development, air pollution, represented by fine particulate matter, has become a primary environmental risk factor threatening public health. As one of the main targets of air pollution control, nitrogen oxides (NOx) primarily originate from coal-fired power plants, industrial furnaces (stationary sources), diesel vehicles, and ocean-going vessels (mobile sources). Large-scale emissions of NOx can trigger a series of environmental problems, including acid rain and photochemical smog. Selective catalytic reduction (NH3-SCR) technology, using ammonia as a reducing agent, is widely recognized as the most effective NOx emission reduction technology, with the catalyst being its core component. It is worth noting that, in addition to developing effective low-temperature catalysts, given the significant temperature fluctuations in flue gas from diesel engines and non-power industries, manufacturing NH3-SCR catalysts with a wide temperature window is also indispensable.

[0003] Generally, strong acidity and excellent redox properties are two key factors enabling SCR catalysts to possess a wide temperature window. Rare earth cerium-based catalysts are abundant in my country and possess high oxygen storage capacity and excellent redox characteristics, attracting widespread attention in NH3-SCR applications. However, their poor surface acidity limits practical applications. Common methods for increasing the acidity of CeO2-based catalysts include acidification, surface sulfidation, and acidic metal oxide doping. It is worth noting that the activity temperature window of most of these modified CeO2-based catalysts remains narrow, making it impossible to simultaneously achieve high-temperature and low-temperature activity. Therefore, how to improve high-temperature activity while maintaining low-temperature activity is a crucial issue worthy of further research.

[0004] Crystalline Zr3SO9 is a nanomaterial with a unique layered structure. SO42- is present in this nanomaterial. 2- Uniformly distributed at the center of the Zr trimer, these sites form strongly acidic sites. The unique interlayer space and strongly acidic sites of Zr3SO9 hold promise for improving the catalytic performance of CeO2 in NH3-SCR. Summary of the Invention

[0005] Objectives of this invention: The first objective is to provide a rare-earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst. The second objective is to provide a method for preparing this rare-earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst, which uses inexpensive and readily available raw materials, has low energy consumption, low pollution, and is environmentally friendly. The third objective is to provide the application of this rare-earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst in flue gas denitration, thereby overcoming the problem that existing CeO2-based modified materials cannot simultaneously meet the requirements for high-temperature and low-temperature activity.

[0006] Technical solution: The rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst of the present invention is a CeO2 dispersed on the surface of Zr3SO9, which is prepared by solid-phase grinding of Zr3SO9 and cerium nitrate and calcination in a muffle furnace.

[0007] Furthermore, the Zr3SO9 has a hexagonal layered structure with an interlayer spacing of 1-1.5 nm, and S is in the form of SO4. 2- The form is distributed in the center of the Zr trimer, forming a strongly acidic site.

[0008] Furthermore, the amount of CeO2 doped in the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst is 0.3-1.5 wt% of Zr3SO9.

[0009] Furthermore, the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst exhibits wide-temperature activity, sulfur resistance, and / or water poisoning resistance at 250-550 ℃.

[0010] A method for preparing a rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to the present invention includes the following steps: mixing Zr3SO9 with Ce(NO3)3·6H2O, grinding, and calcining in a muffle furnace to obtain CeO2 / Zr3SO9.

[0011] Furthermore, the mass ratio of Zr3SO9 to Ce(NO3)3·6H2O is 300:3-15.

[0012] Furthermore, the grinding time is 10-30 min, and the calcination is carried out by heating to 400-500 ℃ at a rate of 3-5 ℃ / min and then calcining for more than 3 hours.

[0013] Furthermore, the preparation method of Zr3SO9 includes the following steps: mixing ZrOCl2 with H2SO4 and reacting them hydrothermally to obtain Zr3SO9 superacid crystals.

[0014] Furthermore, the molar ratio of ZrOCl2 to H2SO4 is 1-2:1-2.

[0015] Furthermore, the hydrothermal reaction temperature is 200-250 ℃, and the hydrothermal reaction time is 48-72 h.

[0016] The present invention also includes the application of the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitrification catalyst described herein in flue gas denitrification.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The present invention uses solid-phase grinding method to couple the redox properties of CeO2 with the strong acidity of Zr3SO9, and successfully prepares rare earth cerium-based coupled Zr3SO9 superacid nanocatalyst CeO2 / Zr3SO9, which exhibits excellent wide temperature activity window in NH3-SCR reaction.

[0018] (2) The CeO2 / Zr3SO9 catalyst of this invention has strong tolerance to SO2 and H2O. Since the raw materials used in this method are inexpensive and readily available, the operation is simple and quick, the energy consumption is low, there are no special requirements for equipment, and there is little additional environmental pollution, it has potential application prospects in the field of flue gas denitrification. Attached Figure Description

[0019] Figure 1 The structural model diagram of Zr3SO9 prepared in Example 1; Figure 2 HAADF-STEM image of Zr3SO9 prepared in Example 1; Figure 3 The XRD pattern of the CeO2 (0.9wt%) / Zr3SO9 composite nanocatalyst prepared in Example 1; Figure 4 TEM image of the CeO2 (0.9 wt%) / Zr3SO9 composite nanocatalyst prepared in Example 1. Figure 5 The results of NO oxidation and H2-TPR are shown for CeO2 (0.9wt%) / Zr3SO9, Zr3SO9 and CeO2; Figure 6 The NH3-TPD results for CeO2 (0.9wt%) / Zr3SO9, Zr3SO9 and CeO2 are shown in the figure. Figure 7 The graph shows the results of the resistance to SO2 / H2O poisoning of CeO2 (0.9wt%) / Zr3SO9 in NH3-SCR. Figure 8A comparison of N2 selectivity results of CeO2 (0.9wt%) / Zr3SO9 and CeO2 in NH3-SCR; Figure 9 The graph shows the change in NO conversion rate of CeO2 / Zr3SO9 with different CeO2 loadings as a function of temperature. Figure 10 The results of the NH3-SCR reaction of CeO2 (0.9wt%) / Zr3SO9-WI and CeO2 (0.9wt%) / Zr3SO9 are shown in the figure. Figure 11 The results of the NH3-SCR reaction of CeO2 (0.9wt%) / ZrS and CeO2 (0.9wt%) / Zr3SO9 are shown in the figure. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0021] Example 1

[0022] 1. Preparation of Zr3SO9 superacid crystals 7.5 mmol ZrOCl2 and 15 mmol sulfuric acid were dissolved in 14 mL H2O and stirred thoroughly until the solution became clear. The solution was then placed in a reaction vessel and hydrothermally reacted at 240 °C for 72 hours. After filtration and washing, the solution was dried in an oven at 110 °C for 12 hours, ground until homogeneous, and then calcined in a muffle furnace at 500 °C for 2 hours under air atmosphere to obtain Zr3SO9 superacid crystals. Its structural model is shown below. Figure 1 As shown.

[0023] The morphology and composition of the Zr3SO9 superacid crystals prepared in this embodiment were characterized, and the results are as follows: Figure 2 As shown.

[0024] Depend on Figure 1-2 As can be seen, the Zr3SO9 material has a hexagonal layered structure with an interlayer spacing of 1.1 nm. S species are present as sulfate (SO4). 2- The acidic sites are evenly distributed in the center of the Zr trimer.

[0025] 2. Preparation of CeO2 / Zr3SO9 composite nanocatalysts 9 mg Ce(NO3)3·6H2O and 0.3 g Zr3SO9 were ground in a mortar for 30 min. The resulting mixed solid was transferred to a muffle furnace and calcined at 450 °C for 3 h in air atmosphere at a rate of 3 °C / min. The CeO2 / Zr3SO9 composite nanocatalyst was thus prepared and was named CeO2(0.9wt%) / Zr3SO9 based on the CeO2 loading.

[0026] The Zr3SO9 superacid crystals and CeO2 (0.9wt%) / Zr3SO9 prepared in this embodiment were subjected to XRD analysis, and the results are as follows: Figure 3 As shown. By Figure 3 It can be seen that the diffraction peaks are mainly attributed to the crystal diffraction peaks of Zr3SO9. After coupling with CeO2, no diffraction peaks of CeO2 were observed in the XRD of the new material, indicating that CeO2 is uniformly dispersed on the surface of Zr3SO9.

[0027] The CeO2 (0.9wt%) / Zr3SO9 prepared in this embodiment was analyzed by TEM, and the results are as follows: Figure 4 As shown. Figure 4 Uniform CeO2 (1 1 1) crystalline phases with a particle size of 2-3 nm and a spacing of 0.31 nm were observed on the surface of Zr3SO9, proving that CeO2 is uniformly dispersed on the surface of Zr3SO9.

[0028] Comparative Example 1 Zr3SO9 superacid crystals were prepared using the same procedure as step 1 in Example 1.

[0029] Comparative Example 2 2 g of Ce(NO3)3·6H2O was placed in a muffle furnace and calcined at 550 °C for 4 h under air atmosphere at a rate of 2 °C / min to obtain solid CeO2.

[0030] Example 2

[0031] 1. The CeO2 (0.9wt%) / Zr3SO9 prepared in Example 1, the Zr3SO9 in Comparative Example 1, and the CeO2 in Comparative Example 2 were used as catalysts for NO oxidation, H2-TPR, and NH3-TPD experiments.

[0032] (1) NO oxidation experiment: The catalytic reaction was carried out in a fixed-bed continuous flow quartz reactor. The catalyst particle size was 60-80 mesh, and the dosage was 100 mg. The reaction gas composition was: 500 ppm NO, 5% O2, and Ar as the equilibrium gas. The gas space velocity in the reaction was 60,000 mL·h. -1 · g -1 cat Before the reaction, the catalyst was purged with high-purity Ar at 500 °C for 0.5 h. The catalytic reaction was carried out at 250–550 °C, and activity data were collected after the reaction reached equilibrium.

[0033] (2) H2-TPR experimental procedure: H2-TPR was carried out in a quartz U-tube reactor connected to a thermal conductivity detector (TCD). An H2 / Ar mixture (7% H2 by volume) was used as the reducing agent. The amount of reagent used was 10 mg. The sample was pretreated at 200 °C for 1 h in a N2 atmosphere and then cooled to room temperature. The reaction atmosphere was switched to an H2 / Ar mixture, and the reaction temperature was increased from room temperature to 500 °C at a rate of 10 °C / min.

[0034] The results are as follows Figure 5 As shown. Figure 5 The figures show the NO oxidation results and H2-TPR results for CeO2 (0.9wt%) / Zr3SO9, Zr3SO9, and CeO2, where (a) represents the NO oxidation results and (b) represents the H2-TPR results. Figure 5 It can be seen that the NO oxidation efficiency of Zr3SO9 is very low. The oxidation efficiency is significantly improved after coupling with CeO2, and the generated NO2 can enhance the low-temperature denitrification performance of the catalyst through a "fast SCR" reaction. However, the oxidizing power of CeO2 (0.9wt%) / Zr3SO9 is much lower than that of pure CeO2. This indicates that the strong acid sites of Zr3SO9 weaken the oxidizing power of CeO2, thereby effectively reducing the excessive oxidation of ammonia at high temperatures and promoting the conversion of NO at high temperatures.

[0035] (3) NH3-TPD experimental procedure: The catalytic reaction was carried out in a fixed-bed continuous flow quartz reactor. The catalyst particle size was 60-80 mesh, and the dosage was 100 mg. The reaction gas composition was: 500 ppm NH3, 5% O2, and Ar as the equilibrium gas. The gas space velocity in the reaction was 60,000 mL·h. -1 · g -1 cat Before the reaction, the catalyst was purged with high-purity Ar at 500 °C for 0.5 h. The catalytic reaction was carried out at 250–550 °C, and activity data were collected after the reaction reached equilibrium. The results are as follows: Figure 6 As shown, the acidity of CeO2 itself is negligible. However, when combined with Zr3SO9, both the acid content and acid strength are significantly improved. The strong acidity of the CeO2 (0.9wt%) / Zr3SO9 composite nanocatalyst provides the necessary conditions for high-temperature NH3-SCR reactions.

[0036] 2. Resistance to SO2 / H2O poisoning by CeO2 (0.9wt%) / Zr3SO9 in NH3-SCR The CeO2 (0.9 wt%) / Zr3SO9 obtained in Example 1 was placed in a fixed-bed quartz reactor for NH3-SCR reaction. The catalyst particle size was 60-80 mesh, and the dosage was 100 mg. The reaction gas composition was: 500 ppm NO, 500 ppm NH3, 200 ppm SO2, 5% H2O, 5% O2, with Ar as the equilibrium gas. The gas hourly space velocity (GHSV) in the reaction was 60,000 mL·h. -1 · g -1 cat The reaction temperatures were 300 ℃ and 500 ℃, respectively. After raising the reactor temperature to the target temperature, NO, NH3, O2, and Ar were introduced. After the reaction was maintained for 1 h, 200 ppm SO2 was added and maintained for 5 h. Then, 5% H2O was introduced and maintained for 13 h. After stopping the introduction of SO2 and H2O, the reaction was continued for 1 h. Activity data were collected after the reaction reached equilibrium. The NO conversion rate and N2 selectivity were calculated using the following formula (1):

[0037] in,[ NO ] in This indicates the initial concentration of NO in the reactant gas at the reactor inlet. NO ] out This indicates the concentration of NO in the reaction gas after the reaction.

[0038] The reaction results are as follows Figure 7 As shown, in the presence of 200 ppm SO2 and 5% H2O, CeO2 (0.9wt%) / Zr3SO9 can still maintain more than 90% of catalytic activity and maintain the activity without decreasing for 18 h.

[0039] 3. Comparison of N2 selectivity between CeO2 and CeO2 / Zr3SO9 in NH3-SCR The CeO2 (0.9 wt%) / Zr3SO9 catalysts obtained in Example 1 and the CeO2 catalysts obtained in Example 2 were respectively placed in a fixed-bed quartz reactor for NH3-SCR reaction. The catalyst particle size was 60-80 mesh, and the dosage was 100 mg. The reaction gas composition was: 500 ppm NO, 500 ppm NH3, 5% O2, with Ar as the equilibrium gas, and the gas space velocity in the reaction was 60000 mL·h. -1 · g -1 cat The reaction temperature is 250 ℃-550 ℃. The N2 selectivity is calculated by the following formula (2).

[0040]

[0041] in,[ NO] in This indicates the initial concentration of NO in the reactant gas at the reactor inlet. NH 3 ] in This indicates the initial concentration of NH3 in the reactant gas at the reactor inlet. NO ] out This indicates the concentration of NO in the reactant gas after the reaction. NH 3 ] out This indicates the concentration of NH3 in the reactant gas after the reaction. NO 2 ] out This indicates the concentration of NO2 in the reactant gas after the reaction. N 2 O ] out These represent the concentrations of N2O in the reaction gas after the reaction.

[0042] The reaction results are as follows Figure 8 As shown, the N2 selectivity of CeO2 as a catalyst decreases with increasing temperature, mainly due to excessive ammonia oxidation at high temperatures, which leads to the production of byproducts such as N2O and NO2. In contrast, CeO2 (0.9wt%) / Zr3SO9 exhibits excellent N2 selectivity across the entire temperature range, and the excessive ammonia oxidation is effectively suppressed.

[0043] Example 3

[0044] The preparation process of CeO2 / Zr3SO9 composite nanocatalyst is the same as in Example 1, except that 3 mg, 6 mg, and 15 mg of Ce(NO3)3·6H2O are used instead of 9 mg of Ce(NO3)3·6H2O in Example 1 to prepare CeO2 (0.3wt%) / Zr3SO9, CeO2 (0.6wt%) / Zr3SO9, and CeO2 (1.5wt%) / Zr3SO9, respectively.

[0045] The CeO2 (0.3wt%) / Zr3SO9, CeO2 (0.6wt%) / Zr3SO9, CeO2 (1.5wt%) / Zr3SO9 prepared in this example, and the CeO2 (0.9wt%) / Zr3SO9 prepared in Example 1 were applied to the NH3-SCR reaction. The experimental procedure was the same as step 3 in Example 4, and the specific reaction conditions were as follows: The catalytic reaction test was carried out in a fixed-bed continuous flow quartz reactor. The catalyst particle size was 60-80 mesh, and the dosage was 100 mg. The reaction gas composition was: 500 ppm NO, 500 ppm NH3, 200 ppm SO2, 5% H2O, 5% O2, with Ar as the equilibrium gas. The gas space velocity in the reaction was 60000 mL·h.-1 · g -1 cat Before the reaction, the catalyst was purged with high-purity Ar at 500 °C for 0.5 h. The catalytic reaction was carried out at 250–550 °C, and activity data were collected after the reaction reached equilibrium. The results are as follows: Figure 9 As shown.

[0046] Figure 9 The graph shows the NO conversion rate of Ce / Zr3SO9 with different CeO2 loadings as a function of temperature. The catalytic performance improves as the CeO2 content increases from 0.3 wt% to 0.9 wt%. However, the high-temperature reactivity of the catalyst decreases significantly when the CeO2 loading is excessive (1.5 wt%). Therefore, the optimal cerium loading for the prepared catalyst is 0.9 wt%, achieving a NO conversion rate of over 90% at 300-540 °C.

[0047] Comparative Example 3: Comparison of different preparation methods The CeO2 (0.9wt%) / Zr3SO9-WI composite nanocatalyst was prepared by a wet impregnation method. The specific steps were as follows: 0.3 g Zr3SO9 was added to 6 mL of Ce(NO3)3 solution (Ce(NO3)3 concentration was 1.5 mg / mL), stirred at 4000 rpm / min for 30 minutes, then evaporated to dryness in a 120 °C water bath and dried overnight in a 100 °C oven. The resulting solid was placed in a muffle furnace and heated to 450 °C at a rate of 10 °C / min in air, then held for 3 h to finally obtain solid CeO2 (0.9wt%) / Zr3SO9-WI.

[0048] The CeO2 (0.9 wt%) / Zr3SO9-WI prepared in this comparative example and the CeO2 (0.9 wt%) / Zr3SO9 prepared in Example 1 were respectively placed in a fixed-bed quartz reactor for NH3-SCR reaction. The catalyst particle size was 60-80 mesh, and the amount was 100 mg. The reaction gas composition was: 500 ppm NO, 500 ppm NH3, 5% O2, and Ar as the equilibrium gas. The gas space velocity in the reaction was 60000 mL·h. -1 · g -1 cat The reaction temperature was 250 ℃-550 ℃. The reaction results are as follows. Figure 10 As shown, compared with the traditional wet impregnation method, the CeO2 (0.9wt%) / Zr3SO9 composite nanocatalyst obtained by the solid-phase grinding method of the present invention exhibits excellent catalytic activity at both low temperature (250–400 ℃) and high temperature (450–550 ℃).

[0049] Comparative Example 4: Comparison of the activities of different carriers Using ZrS as a carrier, the specific preparation process is the same as in Example 1, except that Zr3SO9 is replaced with ZrS, and the resulting solid is CeO2 (0.9wt%) / ZrS.

[0050] The CeO2 (0.9 wt%) / ZrS prepared in this comparative example and the CeO2 (0.9 wt%) / Zr3SO9 prepared in Example 1 were respectively placed in a fixed-bed quartz reactor for NH3-SCR reaction. The catalyst particle size was 60-80 mesh, and the dosage was 100 mg. The reaction gas composition was: 500 ppm NO, 500 ppm NH3, 5% O2, and Ar as the equilibrium gas. The gas space velocity in the reaction was 60000 mL·h. -1 · g -1 cat The reaction temperature was 250 ℃-550 ℃. The reaction results are as follows. Figure 11 As shown, the catalytic activity of CeO2 (0.9wt%) / ZrS gradually increases with increasing temperature, reaching a maximum of approximately 90% at 450 °C, and then rapidly decreases. The reactivity of CeO2 (0.9wt%) / Zr3SO9 rapidly increases to over 90% before 300 °C, and then maintains a conversion rate of over 90% between 300-540 °C. Therefore, it can be concluded that the catalytic temperature window of CeO2 (0.9wt%) / Zr3SO9 is significantly longer than that of CeO2 (0.9wt%) / ZrS.

Claims

1. A rare-earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst, characterized in that, The rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst is CeO2 dispersed on the surface of Zr3SO9, which is prepared by solid-phase grinding of Zr3SO9 and cerium nitrate and calcination in a muffle furnace, with a wide temperature range of 250-550 ℃.

2. The rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to claim 1, characterized in that, The Zr3SO9 has a hexagonal layered structure with an interlayer spacing of 1-1.5 nm, and S is in the form of SO4. 2- The form is distributed in the center of the Zr trimer, forming a strongly acidic site.

3. The rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to claim 1, characterized in that, The amount of CeO2 doped in the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst is 0.3-1.5 wt% of Zr3SO9.

4. The rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to claim 1, characterized in that, The rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst exhibits wide-temperature activity, sulfur resistance, and / or water poisoning resistance at 300-550 ℃.

5. A method for preparing a rare-earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to any one of claims 1-4, characterized in that, Includes the following steps: Zr3SO9 is mixed with Ce(NO3)3·6H2O, ground, and calcined in a muffle furnace to obtain CeO2 / Zr3SO9.

6. The preparation method of the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to claim 5, characterized in that, The mass ratio of Zr3SO9 to Ce(NO3)3·6H2O is 300:3-15, the grinding time is 10-30 min, and the calcination is carried out by heating to 400-500 ℃ at 3-5 ℃ / min and then calcining for more than 3 h.

7. The preparation method of the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to claim 5, characterized in that, The preparation method of Zr3SO9 includes the following steps: mixing ZrOCl2 and H2SO4, and then reacting the mixture hydrothermally to obtain Zr3SO9 superacid crystals.

8. The preparation method of the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to claim 7, characterized in that, The molar ratio of ZrOCl2 to H2SO4 is 1-2:1-2.

9. The preparation method of the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitration catalyst according to claim 7, characterized in that, The hydrothermal reaction temperature is 200-250 ℃, and the hydrothermal reaction time is 48-72 h.

10. The application of the rare earth cerium-based coupled Zr3SO9 superacid wide-temperature denitrification catalyst according to any one of claims 1-4 in flue gas denitrification.

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