Preparation method of copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst

Abstract

The invention discloses a preparation method of a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst, and belongs to the technical field of catalysts. The catalyst comprises the following components: an active component and a carrier for providing physical support for the active component, the active components comprise MnOx, FeOx, CuOx and CuMn2O4, and the carrier is TiO2; the catalyst is represented by aMn-bFe-cCu / Ti, a, b and c sequentially represent molar ratios of three metal elements of Mn, Fe and Cu to TiO2, and a is 0.25-0.35, b is 0.02-0.10, and c is 0.03-0.15. The preparation method comprises the following steps: preparing a catalyst precursor by adopting an excessive impregnation method, fully impregnating the precursor on the carrier TiO2, and drying and roasting to form the catalyst. The catalyst has good NO catalytic oxidation activity in a temperature range of 200-400 DEG C, can maintain good stability and oxidation activity in a high water vapor concentration environment, and has good industrial application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of harmless treatment and recycling of catalysts and waste acids, and in particular to a method for preparing a copper-doped Mn-Fe / TiO2 nitrogen monoxide oxidation catalyst. Background Art

[0002] During the hot rolling and annealing process, a dense oxide film will be formed on the surface of stainless steel. After processing, the stainless steel needs to be pickled to completely remove the surface oxide film to improve the appearance and corrosion resistance. With the annual increase in stainless steel production, a large amount of waste acid is produced every year. The waste acid contains free acids such as HNO3 and HF, NO3 - Acid radical ions and metal ions such as Fe, Ni and Cr. One way to recycle waste acid is fluidized bed roasting, that is, the waste acid is sprayed into the fluidized bed in an atomized state. At high temperature, the fluoride salts in the waste acid decompose into metal oxides and HF, and the nitrates first decompose into metal oxides and NO2, and NO2 further decomposes into NO and O2. In the high-temperature flue gas produced by roasting, the concentration of NO is between 800 and 1800 ppm, and the concentration of water vapor is between 10 vol.% and 40 vol.%, which is much higher than the concentration in the flue gas of conventional coal-fired power plant boilers. In order to realize the recycling of nitric acid, it is necessary to oxidize the NO in the roasting flue gas to NO2, and then absorb and oxidize it to nitric acid (HNO3) by the absorbent. The obtained nitric acid can be used in the pickling process to simultaneously realize the pollution control and resource recycling of waste acid.

[0003] Without external intervention, the process of NO oxidation to NO2 is slow. There are many ways to oxidize NO. Based on the characteristics of waste acid roasting flue gas and resource recovery needs, it is necessary to choose a method that can achieve efficient oxidation of NO at a higher water vapor concentration without producing other impurities. Compared with gas-phase and liquid-phase oxidants and plasma oxidation, catalytic oxidation of NO has the advantages of no need for external oxidants and relatively low energy consumption, and is currently the first choice in this field.

[0004] In terms of catalyst selection, precious metals, such as platinum (Pt)-based catalysts, are more active, but their high cost limits their large-scale industrial application. Transition metal oxide catalysts have the advantages of high catalytic activity, low cost and high yield, and have become a hot spot in the field of NO catalytic oxidation. Studies have shown that the catalytic oxidation ability of Mn-based catalysts is better than that of other non-precious metal catalysts. Doping iron or rare earth elements in metal oxide-supported catalysts can further enhance the adsorption capacity of O2 on the catalyst surface and improve the reaction ability of NO with O2.

[0005] The invention patent with publication number CN112439406A provides a catalyst for catalytic oxidation of NO, its preparation method and application. In this scheme, the catalyst is mainly composed of metal oxides, the carrier is TiO2, the active component is a composite oxide composed of Mn, Fe, La and Ce, and MoO3 is an additive. The obtained catalyst has good NO catalytic activity in the range of 150°C to 350°C. Although there have been many studies on the synergistic effect of Mn and Fe in the catalytic oxidation of NO in the past, the catalyst composed of them has average resistance to water. The adsorption of water vapor in the flue gas will reduce the performance of the catalyst, restricting the scope of practical application.

[0006] The invention patent with publication number CN111167477A provides a method for preparing a cobalt-modified NO catalytic oxidant. The active components of this scheme include RuO2, Co3O4, CeO2 and ZrO2, which are prepared by coprecipitation. The obtained catalyst has improved catalytic oxidation activity and sulfur and water resistance. However, the prepared catalyst can only maintain 55% of the catalytic oxidation activity when there is 5 vol.% water vapor in the flue gas, which is much lower than when there is no water vapor.

[0007] The NO catalytic oxidation effect of common NO oxidation catalysts in flue gas with high concentration of water vapor is sharply reduced, and it is not suitable for flue gas produced by waste acid roasting. Therefore, it is of great significance to develop low-cost and water-resistant transition metal NO oxidation catalysts. Summary of the invention

[0008] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst with excellent catalytic performance and good water resistance is provided, and the components of the catalyst include an active component and a carrier that provides physical support for the active component; the active component includes MnO x ,FeO x , CuO x and CuMn2O4, with TiO2 as the carrier; the catalyst is represented by aMn-bFe-cCu / Ti, wherein a, b, c represent the molar ratios of three metal elements, Mn, Fe and Cu, to TiO2, respectively, and satisfy a=0.25~0.35, b=0.02~0.10, c=0.03~0.15.

[0009] In a second aspect of the present invention, a method for preparing a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst having convenient process, wide raw material acquisition, and suitable for industrial production is provided, comprising the following steps: 1) Dissolve corresponding amounts of manganese salt, iron salt and copper salt in water according to the molar ratio to obtain a metal salt solution; 2) Add a corresponding amount of carrier TiO2 to the metal salt solution and stir to form a mixed solution; 3) The mixed solution is continuously stirred at a certain temperature until the water is basically evaporated to obtain a solid; 4) The solids are dried to obtain dry matter; 5) The dry matter is calcined, ground, and stirred to obtain a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst.

[0010] Preferably, in step 1), the metal salt is a water-soluble salt of the corresponding metal, including at least one of its nitrate, sulfate and chloride.

[0011] Preferably, in step 2), TiO2 is anatase TiO2.

[0012] Preferably, in step 2), stirring is performed at room temperature for 12 h to 24 h.

[0013] Preferably, in step 3), the mixed solution is continuously stirred at 50° C. to 90° C. until the water is substantially evaporated.

[0014] Preferably, in step 4), the drying temperature is 100° C. to 110° C., and the drying time is 12 h to 24 h.

[0015] Preferably, in step 5), the calcination temperature is 450° C. to 550° C., and the calcination time is 3 h to 4 h.

[0016] During the calcination process, too low a temperature may lead to incomplete reaction, while too high a temperature will cause the phase of manganese to change from manganese dioxide to manganese trioxide, affecting the catalytic activity. Therefore, the treatment temperature of this step should be controlled within the preferred temperature range.

[0017] Preferably, in step 5), the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst is ground so that the powder particle size is 60-120 mesh.

[0018] In a third aspect of the present invention, there is provided a use of a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst in catalytic oxidation of NO.

[0019] Preferably, in the application, the catalytic temperature of the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst is 200°C to 400°C.

[0020] The catalyst of the present invention has good catalytic performance and water resistance in a wide range of temperatures and can be used in a wider range of occasions. The catalyst is suitable for catalytic oxidation of NO in flue gas containing water vapor at 200°C to 400°C, and is also suitable for the oxidation recovery process of flue gas generated after waste acid is roasted in a fluidized bed. In particular, in the temperature range of 300°C to 350°C, the catalytic conversion rate of NO in a high-concentration water vapor environment can reach more than 70%.

[0021] Based on the above technical solutions, the design concept and principle of the present invention are as follows: The present invention uses TiO2 as a carrier to carry metals; and adopts an over-impregnation method to prepare a catalyst precursor. After the precursor is fully impregnated in the carrier TiO2, it is dried and calcined to form a catalyst. Among the active components, MnO x Due to its multivalent chemical properties and porosity, it exhibits excellent activity in NO oxidation reactions. Fe and Mn will affect each other when loaded, making the metal elements more evenly distributed, which is conducive to enhancing the electron transfer between ions and the concentration of oxygen vacancies, and improving the oxidation activity of the catalyst. Cu was previously used for the catalytic oxidation of CO and other substances, and there is little research in the field of NO catalytic oxidation. The present applicant found in the research and development that doping Cu into the Mn-Fe / TiO2 catalyst improves the dispersion of metal oxides on the surface and combines with Mn to form a new CuMn2O4 phase, which increases the Mn 4+ and the number of oxygen vacancies. Mn 4+ Compared with Mn in NO catalytic oxidation 3+ It has stronger redox activity and is the active center of the reaction. Oxygen vacancies mean a stronger ability to activate oxygen. Their increase is conducive to improving the NO oxidation activity of the catalyst. Cu doping also enhances the diversity of metal ion valence states, which is conducive to electron migration between metal ions. Mn 4+ +Cu + Mn 3+ +Cu 2+ and Fe 3+ +Cu + Fe 2+ +Cu 2+ The circulation between Cu and Mn-Fe / TiO2 improves the redox ability of the catalyst, which is beneficial to the catalytic oxidation of NO. In addition, Cu also reduces the acidity and alkalinity of the catalyst surface, which is beneficial to reduce the adsorption of water and thus improve the competitive adsorption of NO in the flue gas. In summary, Cu doping into Mn-Fe / TiO2 improves the catalytic oxidation activity of the catalyst from two aspects: enhancing the oxidation ability of NO and reducing the competitive adsorption of H2O.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects: The invention provides a copper-doped Mn-Fe / TiO2 nitrogen monoxide oxidation catalyst. The catalyst introduces Cu and a Mn-Fe system to cooperate with each other, thereby significantly improving the NO catalytic oxidation activity and water resistance of the catalyst.

[0023] The invention provides a method for preparing a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst, which has a convenient process, wide raw material acquisition, is suitable for industrial production, and can prepare a high-performance product at a low price.

[0024] The invention provides an application of a copper-doped Mn-Fe / TiO2 nitrogen monoxide oxidation catalyst, which has good application prospects in NO catalytic oxidation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the preparation process of copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst; Figure 2 The NO oxidation efficiency diagram of the catalysts prepared in Examples 1 to 5 at 200° C. to 400° C. in Test Example 1; Figure 3 The NO oxidation efficiency diagram of the catalyst prepared in Example 1 at different NO concentrations at 200° C. to 400° C. in Test Example 2; Figure 4 This is a graph of the NO oxidation efficiency of the catalyst prepared in Example 1 at 200°C~400°C under different water vapor concentrations in Test Example 3. DETAILED DESCRIPTION

[0026] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0027] Example 1 The copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst of this embodiment is prepared by the following method: Figure 1 As shown: 1) Weigh 16.110 g of manganese nitrate solution, 2.424 g of ferric nitrate nonahydrate, and 4.349 g of copper nitrate trihydrate, add them into 15 mL of deionized water and stir thoroughly until they are completely dissolved to obtain a metal salt solution; 2) Add 12 g of carrier TiO2 to the metal salt solution and continue stirring for 24 h to allow the active components to be fully impregnated on the carrier to obtain a mixed solution; 3) The mixed solution is continuously stirred at 90°C until the water is basically evaporated to obtain a solid; 4) Dry the solids in an oven at 110 °C for 12 h. The solids are black in color and then taken out and fully ground to obtain dry matter. 5) The dry matter was placed in a muffle furnace and calcined at 500 °C for 4 h, then taken out and fully ground and sieved to 60-120 mesh, and stirred to mix, to obtain a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst with a molar ratio of each element of Mn:Fe:Cu:Ti=0.3:0.04:0.12:1, which was recorded as catalyst #1.

[0028] Example 2 The copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst of this embodiment is prepared by the following method: 1) Weigh 16.110 g of manganese nitrate solution, 2.424 g of ferric nitrate nonahydrate, and 3.262 g of copper nitrate trihydrate, add them into 15 mL of deionized water and stir thoroughly until they are completely dissolved to obtain a metal salt solution; 2) Add 12 g of carrier TiO2 to the metal salt solution and continue stirring for 24 h to allow the active components to be fully impregnated on the carrier to obtain a mixed solution; 3) The mixed solution is continuously stirred at 80°C until the water is basically evaporated to obtain a solid; 4) Dry the solids in an oven at 100 °C for 24 h. The solids are black in color and then taken out and fully ground to obtain dry matter. 5) The dry matter was placed in a muffle furnace and calcined at 500 °C for 3 h, then taken out and fully ground and sieved to 60-120 mesh, and stirred to mix, to obtain a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst with a molar ratio of each element of Mn:Fe:Cu:Ti=0.3:0.04:0.09:1, which was recorded as catalyst #2.

[0029] Example 3 The copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst of this embodiment is prepared by the following method: 1) Weigh 16.110 g of manganese nitrate solution, 2.424 g of ferric nitrate nonahydrate, and 5.436 g of copper nitrate trihydrate, add them into 15 mL of deionized water and stir thoroughly until they are completely dissolved to obtain a metal salt solution; 2) Add 12 g of carrier TiO2 to the metal salt solution and continue stirring for 24 h to allow the active components to be fully impregnated on the carrier to obtain a mixed solution; 3) The mixed solution is continuously stirred at 70°C until the water is basically evaporated to obtain a solid; 4) Dry the solids in an oven at 110 °C for 12 h. The solids are black in color and then taken out and fully ground to obtain dry matter. 5) The dry matter was placed in a muffle furnace and calcined at 550 °C for 4 h, then taken out and fully ground and sieved to 60-120 mesh, and stirred to mix, to obtain a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst with a molar ratio of each element of Mn:Fe:Cu:Ti=0.3:0.04:0.15:1, which was recorded as catalyst #3.

[0030] Example 4 The copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst of this embodiment is prepared by the following method: 1) Weigh 16.110 g of manganese nitrate solution, 6.060 g of ferric nitrate nonahydrate, and 1.087 g of copper nitrate trihydrate, add them into 15 mL of deionized water and stir thoroughly until they are completely dissolved to obtain a metal salt solution; 2) Add 12 g of carrier TiO2 to the metal salt solution and continue stirring for 24 h to allow the active components to be fully impregnated on the carrier to obtain a mixed solution; 3) The mixed solution is continuously stirred at 60°C until the water is basically evaporated to obtain a solid; 4) Dry the solids in an oven at 110 °C for 12 h. The solids are black in color and then taken out and fully ground to obtain dry matter. 5) The dry matter was placed in a muffle furnace and calcined at 450 °C for 4 h, then taken out and fully ground and sieved to 60-120 mesh, and stirred to mix, to obtain a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst with a molar ratio of each element of Mn:Fe:Cu:Ti=0.3:0.04:0.03:1, which was recorded as catalyst #4.

[0031] Example 5 The copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst of this embodiment is prepared by the following method: 1) Weigh 16.110 g of manganese nitrate solution, 1.212 g of ferric nitrate nonahydrate, and 2.174 g of copper nitrate trihydrate, add them into 15 mL of deionized water and stir thoroughly until they are completely dissolved to obtain a metal salt solution; 2) Add 12 g of carrier TiO2 to the metal salt solution and continue stirring for 12 h to allow the active components to be fully impregnated on the carrier to obtain a mixed solution; 3) The mixed solution is continuously stirred at 50°C until the water is basically evaporated to obtain a solid; 4) Dry the solids in an oven at 110 °C for 12 h. The solids are black in color and then taken out and fully ground to obtain dry matter. 5) The dry matter was placed in a muffle furnace and calcined at 500 °C for 4 h, then taken out and fully ground and sieved to 60-120 mesh, and stirred to mix, to obtain a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst with a molar ratio of each element of Mn:Fe:Cu:Ti=0.3:0.04:0.03:1, which was recorded as catalyst #5.

[0032] Test Example 1 This test example uses the catalysts prepared in Examples 1 to 5 (catalyst 1# to catalyst 5#) as examples to test the NO catalytic oxidation activity. The raw gas composition used in the test is as follows: 800 ppm NO, 6 vol.% O2, 35 vol.% H2O, the carrier gas is N2, and the space velocity is 12000 h -1 The catalytic oxidation efficiency of the catalyst was tested at 200-400 °C. The test results are as follows: Figure 2 shown.

[0033] It can be seen from the test results that the doping amount of each metal element will affect the catalytic activity of the catalyst, and Cu has a significant effect; the NO catalytic oxidation activity of the Cu-doped Mn-Fe / TiO2 catalyst first increases and then decreases with the increase of temperature, and shows good catalytic oxidation performance in the environment with a high concentration of water vapor. At 325 ℃, the NO conversion rate can reach a maximum of 74.00%.

[0034] Test Example 2 This test example takes the catalyst prepared in Example 1 as an example, and conducts NO catalytic oxidation activity test at different NO concentrations (800-1600 ppm). The test raw gas composition is as follows: 800ppm, 1200ppm, 1600ppm NO, 6 vol.% O2, 35vol.% H2O, carrier gas is N2, and the space velocity is 12000 h -1 The catalytic oxidation efficiency of the catalyst was tested at 200℃~400℃. The test results are as follows: Figure 3 shown.

[0035] It can be seen from the test results that: with the gradual increase of NO concentration, the catalytic activity of the catalyst gradually decreases, but the Cu-doped Mn-Fe / TiO2 catalyst can still show good catalytic oxidation performance in flue gas with high NO concentration. At 325°C, the conversion rate still reaches 50.67% when the NO concentration is 1600 ppm.

[0036] Test Example 3 This test example takes the catalyst prepared in Example 1 as an example, and conducts NO catalytic oxidation activity test at different H2O concentrations (0-35 vol.%). The test raw gas composition is as follows: 800 ppm NO, 6 vol.% O2, 0 vol.%, 10 vol.%, 20 vol.%, 35 vol.% H2O, carrier gas is N2, and the space velocity is 12000 h -1 The catalytic oxidation efficiency of the catalyst was tested at 200-400 °C. The test results are as follows: Figure 4 shown.

[0037] It can be seen from the test results that the water vapor concentration significantly affects the NO catalytic oxidation activity of the catalyst. As the water vapor concentration increases, the catalytic activity of the catalyst gradually decreases. Catalyst 1# exhibits good catalytic oxidation performance in the presence or absence of water vapor. At 325 °C, the NO conversion rate can reach 80.53% in the absence of water vapor, indicating that this catalyst is not only suitable for the catalytic oxidation of NO in the flue gas environment of waste acid roasting, but also has good performance for conventional flue gas.

[0038] Currently CuO x Oxides have been less studied and applied in NO catalytic oxidation. In combination with the above results, the present invention introduces Cu and Mn-Fe system to synergize and significantly improve the electron migration, redox property and surface acidity and alkalinity of the catalyst. This is beneficial to the catalytic oxidation of NO in the flue gas after the waste acid is roasted. Since this flue gas contains a high concentration of water vapor and NO, the use of other catalysts will significantly reduce the catalytic activity.

[0039] At present, there are few studies on the water resistance of NO catalytic oxidants. Most existing NO catalytic oxidants cannot obtain good catalytic activity under the condition of high concentration of H2O. The present invention provides a method for preparing a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst. Compared with the preparation methods of most catalysts, the preparation process of the catalyst of the present invention is relatively simple and suitable for industrial application. The obtained catalyst has a high water vapor content (35 vol.% H2O, 800 ppm NO, 6 vol.% O2, carrier gas is N2, temperature is 325 °C, space velocity is 12000 h -1 ) under the condition of 74.00% NO conversion rate. When the NO concentration is 1600 ppm, the conversion rate can reach up to 50.67%. The catalyst has good catalytic activity and water resistance, and has good application prospects in NO catalytic oxidation.

[0040] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst, characterized in that: The components of the catalyst include active components and a carrier that provides physical support for the active components; the active components include MnO x ,FeO x , CuO x and CuMn2O4, with TiO2 as the carrier; the catalyst is represented by aMn-bFe-cCu / Ti, wherein a, b, c represent the molar ratios of three metal elements, Mn, Fe and Cu, to TiO2, respectively, and satisfy a=0.25~0.35, b=0.02~0.10, c=0.03~0.

15.

2. A method for preparing the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst as claimed in claim 1, characterized in that: The steps include: 1) Dissolve corresponding amounts of manganese salt, iron salt and copper salt in water according to the molar ratio to obtain a metal salt solution; 2) Add a corresponding amount of carrier TiO2 to the metal salt solution and stir to form a mixed solution; 3) The mixed solution is continuously stirred at a certain temperature until the water is basically evaporated to obtain a solid; 4) The solids are dried to obtain dry matter; 5) The dry matter is calcined, ground, and stirred to obtain a copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst.

3. The method for preparing the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst according to claim 2, characterized in that: In the step 1), the metal salt is a water-soluble salt of the corresponding metal, including at least one of its nitrate, sulfate and chloride.

4. The method for preparing the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst according to claim 2, characterized in that: In the step 2), the TiO2 is anatase TiO2; the stirring is carried out at room temperature for 12 h to 24 h.

5. The method for preparing the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst according to claim 2, characterized in that: In the step 3), the mixed solution is continuously stirred at 50° C. to 90° C. until the water is substantially evaporated.

6. The method for preparing the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst according to claim 2, characterized in that: In the step 4), the drying temperature is 100° C. to 110° C., and the drying time is 12 h to 24 h.

7. The method for preparing the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst according to claim 2, characterized in that: In the step 5), the calcination temperature is 450° C. to 550° C., and the calcination time is 3 h to 4 h.

8. The method for preparing the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst according to claim 2, characterized in that: In the step 5), the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst is ground to a powder particle size of 60-120 meshes.

9. Use of the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst as claimed in claim 1 or the copper-doped Mn-Fe / TiO2 nitric oxide oxidation catalyst prepared by the preparation method as claimed in any one of claims 2 to 8 in catalytic oxidation of NO.

10. The use according to claim 9, characterized in that: The catalytic temperature of the copper-doped Mn-Fe / TiO2 NO oxidation catalyst is 200℃~400℃.

Images