Low-temperature NH3-SCR denitration catalyst and preparation method thereof

Abstract

The invention provides a low-temperature NH3-SCR denitration catalyst and a preparation method thereof, and relates to the technical field of catalysts, the catalyst comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier, and the coating material comprises, by mass, 10-30 wt% of MnO2, 0-5 wt% of Nd2O3, 0-10 wt% of MoO3, 0-10 wt% of WO3, 0-5 wt% of Cr2O3, 0-5 wt% of Fe2O3, 20-40 wt% of CeO2 and 20-80 wt% of TiO2. According to the low-temperature NH3-SCR denitration catalyst and the preparation method thereof, the removal rate of nitric oxide can reach 60%-100% when the flue gas temperature is 100-300 DEG C, meanwhile, the low-temperature NH3-SCR denitration catalyst has high water resistance and sulfur resistance, the firmness of a catalyst coating is good, the low-temperature NH3-SCR denitration catalyst has large application prospects, and the preparation method is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a low-temperature NH3-SCR denitration catalyst and a preparation method thereof. Background Art

[0002] With the development of industrial economy, people pay more and more attention to environmental pollution. Particulate matter (PM), volatile organic compounds (VOC), sulfur dioxide (SO2) and nitrogen oxides (NO x ) is the main source of ecological and environmental problems such as acid rain, haze and photochemical smog, which have seriously affected people’s normal production and life and the sustainable development of the national economy.

[0003] Flue gas emissions from fixed sources such as coal-fired power plants and tail gas emissions from mobile sources such as motor vehicles are one of the important factors for excessive PM2.5 in the ecological environment and frequent occurrence of smog weather. my country has successively introduced a number of measures and laws and regulations on environmental governance. Currently, dust removal and desulfurization technologies have been widely used in non-electric industries. Only nitrogen oxide pollution has not been effectively controlled.

[0004] For coal-fired power plants, the current commercial selective catalytic reduction (SCR) denitrification catalyst has an active temperature of 300-420°C, stable operation, and low impurity content in the flue gas. The denitrification catalyst has high activity, good selectivity, and long service life under this operating condition; however, compared with coal-fired power plants, the flue gas emitted by non-electric industries such as glass, coking, cement, industrial kilns, waste incineration and chemical plants has a lower temperature, ranging from 100 to 300°C, and the concentration of SO2 and H2O in the exhaust gas is high. The currently widely used denitrification catalyst is difficult to adapt to this operating condition. Therefore, it is particularly important to develop a catalyst with high activity under low temperature conditions (100-300°C) and strong resistance to sulfur and water poisoning. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a low-temperature NH3-SCR denitration catalyst and a preparation method thereof, wherein the catalyst has a high nitrogen oxide removal rate and has high water and sulfur resistance.

[0006] The technical solution adopted by the present invention is:

[0007] A low-temperature NH3-SCR denitrification catalyst, which includes a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier. Calculated by mass percentage, the coating material includes 10-30wt% of MnO2, 0-5wt% of Nd2O3, 0-10wt% of MoO3, 0-10wt% of WO3, 0-5wt% of Cr2O3, 0-5wt% of Fe2O3, 20-40wt% of CeO2 and 20-80wt% of TiO2.

[0008] Preferably, in the low-temperature NH3-SCR denitration catalyst, the coating amount of the coating material is 50 to 200 g / L.

[0009] The present application also provides a method for preparing a low-temperature NH3-SCR denitration catalyst, which comprises the following steps:

[0010] Step S1, according to the mass percentage of MnO2, Nd2O3, MoO3, WO3 and CeO2, the corresponding manganese precursor, neodymium precursor, molybdenum precursor, tungsten precursor and cerium precursor are weighed, and the manganese precursor is prepared into a precursor solution, and then the manganese precursor solution, the neodymium precursor, the molybdenum precursor and the tungsten precursor are added to deionized water and mixed and stirred evenly, and the pH is adjusted to 3.0-3.5 with nitric acid to obtain a clear solution, and then the cerium precursor is added to the clear solution and stirred for 1-3h to obtain a first mixed solution, and then ammonia water is added dropwise to adjust the pH value of the first mixed solution to 10-11 to obtain a second mixed solution, and then the second mixed solution is moved into a hydrothermal reactor for hydrothermal reaction, and after the hydrothermal reaction is completed, the second mixed solution is filtered, and the filter cake obtained by filtration is calcined to obtain Mn-Nd-Mo-W-CeO x Composite oxides;

[0011] Step S2: weigh the corresponding chromium precursor, iron precursor and titanium oxide powder according to the mass percentage of Cr2O3, Fe2O3 and TiO2, then add the iron precursor and chromium precursor into deionized water and stir evenly, and then add the Mn-Nd-Mo-W-CeO prepared in step S1 in sequence. x The composite oxide, titanium oxide powder and aluminum sol are stirred evenly to obtain a mixed slurry, the pH value of the mixed slurry is adjusted to 3-5 with nitric acid, and then ground and mixed evenly, the solid content of the mixed slurry is controlled to be 20-50%, and stirred for use;

[0012] Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying, and calcining to obtain a low-temperature NH3-SCR denitration catalyst.

[0013] Preferably, in the method for preparing the low-temperature NH3-SCR denitration catalyst, the manganese precursor in step S1 is selected from one of manganese nitrate, manganese acetate, and manganese chloride; the neodymium precursor is selected from one of neodymium nitrate, neodymium sulfate, neodymium carbonate, neodymium phosphate, neodymium chloride, and neodymium acetate; the molybdenum precursor is selected from molybdic acid or ammonium molybdate; the tungsten precursor is selected from ammonium tungstate or ammonium metatungstate; and the cerium precursor is cerium oxide.

[0014] Preferably, in the method for preparing the low-temperature NH3-SCR denitration catalyst, the temperature of the hydrothermal reaction in step S1 is 100-150° C., and the reaction time is 8-12 hours.

[0015] Preferably, in the method for preparing the low-temperature NH3-SCR denitration catalyst, the calcination temperature in step S1 is 450-550° C. and the calcination time is 2-4 hours.

[0016] Preferably, in the method for preparing the low-temperature NH3-SCR denitration catalyst, the iron precursor in step S2 is selected from one of ferric nitrate, ferric sulfate, ferric chloride, and ferric acetate; and the chromium precursor is selected from one of chromium nitrate, chromium carbonate, and chromium chloride.

[0017] Preferably, in the method for preparing the low-temperature NH3-SCR denitration catalyst, the drying temperature in step S3 is 120° C.-150° C., and the drying time is 5-15 min.

[0018] Preferably, in the method for preparing the low-temperature NH3-SCR denitration catalyst, the calcination temperature in step S3 is 450-550° C. and the calcination time is 2-4 hours.

[0019] Advantages of the present invention:

[0020] The low-temperature NH3-SCR denitration catalyst and the preparation method thereof of the present invention can achieve a nitrogen oxide removal rate of 60%-100% at a flue gas temperature between 100°C and 300°C, and at the same time has high water and sulfur resistance, good catalyst coating firmness, great application prospects, and a simple preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a test chart of the water resistance and sulfur resistance of the catalysts of Example 1, Example 6 and the comparative example of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific embodiments.

[0023] In the following embodiments, a square cordierite honeycomb ceramic carrier with a length, width and height of 150×150×150 mm and a mesh size of 75 is used. The carrier volume is 3.375 L and the carrier weight is 1.288-1.324 Kg.

[0024] Example 1

[0025] A low-temperature NH3-SCR denitration catalyst comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier, wherein the coating material comprises, by mass percentage, 10wt% of MnO2, 5wt% of Nd2O3, 10wt% of MoO3, 10wt% of WO3, 5wt% of Cr2O3, 5wt% of Fe2O3, 20wt% of CeO2 and 35wt% of TiO2; and the coating amount of the coating material is 80g / L.

[0026] The preparation method of the low-temperature NH3-SCR denitration catalyst of this embodiment comprises the following steps:

[0027] Step S1, adding 20 parts by weight of a 50% mass fraction manganese nitrate solution to 100 parts by weight of deionized water, then sequentially adding 9.81 parts by weight of neodymium nitrate hexahydrate, 15.31 parts by weight of ammonium molybdate and 14.67 parts by weight of ammonium metatungstate, mixing and stirring evenly, adjusting the pH to 3.0 with nitric acid to obtain a clear solution, then adding 20 parts by weight of CeO2 powder to the clear solution and continuing to stir for 2 hours to obtain a first mixed solution, then dropping ammonia water to adjust the pH value of the first mixed solution to 10 to obtain a second mixed solution, and then moving the second mixed solution into a hydrothermal reactor for hydrothermal reaction, the hydrothermal reaction temperature is 100°C, the reaction time is 12 hours, after the hydrothermal reaction is completed, filtering the second mixed solution, and calcining the filter cake obtained by filtration to obtain Mn-Nd-Mo-W-CeO x Composite oxide, calcination temperature is 450℃, calcination time is 4h;

[0028] Step S2: 8.36 parts by weight of ferric nitrate nonahydrate and 15.66 parts by weight of chromium nitrate were added to 80 parts by weight of deionized water in sequence and stirred evenly, and then 55 parts by weight of Mn-Nd-Mo-W-CeO x The composite oxide, 35 parts by weight of titanium oxide powder and 1 part by weight of aluminum sol binder are prepared into a mixed slurry, the pH value of the mixed slurry is adjusted to 3 with nitric acid, and then ground and mixed evenly, the solid content of the mixed slurry is controlled to 20%, and stirred for standby use;

[0029] Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying at 120° C. for 10 min, and calcining at 450° C. for 4 h to obtain a low-temperature NH3-SCR denitration catalyst.

[0030] Example 2

[0031] A low-temperature NH3-SCR denitration catalyst comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier, wherein the coating material comprises, by mass percentage, 15wt% of MnO2, 3wt% of Nd2O3, 7wt% of MoO3, 5wt% of WO3, 5wt% of Cr2O3, 25wt% of CeO2 and 40wt% of TiO2; and the coating amount of the coating material is 100g / L.

[0032] The preparation method of the low-temperature NH3-SCR denitration catalyst of this embodiment comprises the following steps:

[0033] Step S1, add 30 parts by weight of a 50% mass fraction manganese nitrate solution to 100 parts by weight of deionized water, then add 5.89 parts by weight of neodymium nitrate hexahydrate, 10.72 parts by weight of ammonium molybdate and 7.34 parts by weight of ammonium metatungstate in sequence, mix and stir evenly, adjust the pH to 3.0 with nitric acid to obtain a clear solution, then add 25 parts by weight of CeO2 powder to the clear solution and continue stirring for 2 hours to obtain a first mixed solution, adjust the pH to 3.2 with nitric acid to obtain a clear solution, then add CeO2 powder to the clear solution and continue stirring for 2 hours to obtain a first mixed solution, then drop ammonia water to adjust the pH value of the first mixed solution to 10.5 to obtain a second mixed solution, and then move the second mixed solution into a hydrothermal reactor for hydrothermal reaction, the hydrothermal reaction temperature is 150°C, the reaction time is 8 hours, after the hydrothermal reaction is completed, filter the second mixed solution, and calcine the filter cake obtained by filtration to obtain Mn-Nd-Mo-W-CeO x Composite oxide, calcination temperature is 550℃, calcination time is 2h;

[0034] Step S2: 5.66 parts by weight of chromium nitrate were added to 80 parts by weight of deionized water and stirred evenly, and then 55 parts by weight of Mn-Nd-Mo-W-CeO x The composite oxide, 40 parts by weight of titanium oxide powder and 1 part by weight of aluminum sol binder are prepared into a mixed slurry, and the pH value of the mixed slurry is adjusted to 5 with nitric acid, and then ground and mixed evenly, and the solid content of the mixed slurry is controlled to 50%, and stirred for use;

[0035] Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying at 120° C. for 15 min, and calcining at 500° C. for 3 h to obtain a low-temperature NH3-SCR denitration catalyst.

[0036] Example 3

[0037] A low-temperature NH3-SCR denitrification catalyst comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier, wherein the coating material comprises, by mass percentage, 20wt% of MnO2, 3wt% of MoO3, 7wt% of WO3, 5wt% of Fe2O3, 30wt% of CeO2 and 35wt% of TiO2; and the coating amount of the coating material is 110g / L.

[0038] The preparation method of the low-temperature NH3-SCR denitration catalyst of this embodiment comprises the following steps:

[0039] Step S1, adding 40 parts by weight of a 50% mass fraction manganese nitrate solution to 100 parts by weight of deionized water, then adding 15.31 parts by weight of ammonium molybdate and 4.41 parts by weight of ammonium metatungstate in sequence, mixing and stirring evenly, adjusting the pH to 3.5 with nitric acid to obtain a clear solution, then adding 30 parts by weight of CeO2 powder to the clear solution and continuing to stir for 2 hours to obtain a first mixed solution, then dropping ammonia water to adjust the pH value of the first mixed solution to 10.6 to obtain a second mixed solution, and then moving the second mixed solution into a hydrothermal reactor for hydrothermal reaction, the hydrothermal reaction temperature is 140°C, the reaction time is 12 hours, after the hydrothermal reaction is completed, filtering the second mixed solution, and calcining the filter cake obtained by filtration to obtain Mn-Mo-W-CeO x Composite oxide, calcination temperature is 500℃, calcination time is 3h;

[0040] Step S2: 8.36 parts by weight of ferric nitrate nonahydrate were added to 80 parts by weight of deionized water and stirred evenly, and then 65 parts by weight of Mn-Mo-W-CeO x The composite oxide, 35 parts by weight of titanium oxide powder and 1 part by weight of aluminum sol binder are prepared into a mixed slurry, the pH value of the mixed slurry is adjusted to 4 with nitric acid, and then ground and mixed evenly, the solid content of the mixed slurry is controlled to 40%, and stirred for standby use;

[0041] Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying at 130° C. for 12 min, and calcining at 550° C. for 2 h to obtain a low-temperature NH3-SCR denitration catalyst.

[0042] Example 4

[0043] A low-temperature NH3-SCR denitration catalyst comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier, wherein the coating material comprises, by mass percentage, 25wt% of MnO2, 2wt% of Nd2O3, 5wt% of WO3, 5wt% of Cr2O3, 35wt% of CeO2 and 28wt% of TiO2; and the coating amount of the coating material is 120g / L.

[0044] The preparation method of the low-temperature NH3-SCR denitration catalyst of this embodiment comprises the following steps:

[0045] Step S1, adding 50 parts by weight of a 50% mass fraction manganese nitrate solution to 100 parts by weight of deionized water, then adding 3.92 parts by weight of neodymium nitrate hexahydrate and 7.34 parts by weight of ammonium metatungstate in sequence, mixing and stirring evenly, adjusting the pH to 3.0 with nitric acid to obtain a clear solution, then adding 35 parts by weight of CeO2 powder to the clear solution and continuing to stir for 2 hours to obtain a first mixed solution, then dropping ammonia water to adjust the pH value of the first mixed solution to 11 to obtain a second mixed solution, and then moving the second mixed solution into a hydrothermal reactor for hydrothermal reaction, the hydrothermal reaction temperature is 120°C, the reaction time is 10 hours, after the hydrothermal reaction is completed, filtering the second mixed solution, and calcining the filter cake obtained by filtration to obtain Mn-Nd-W-CeO x Composite oxide, calcination temperature is 450℃, calcination time is 4h;

[0046] Step S2: 15.66 parts by weight of chromium nitrate were added to 80 parts by weight of deionized water and stirred evenly, and then 63 parts by weight of Mn-Nd-W-CeO x The composite oxide, 28 parts by weight of titanium oxide powder and 1 part by weight of aluminum sol binder are prepared into a mixed slurry, and the pH value of the mixed slurry is adjusted to 4.5 with nitric acid, and then ground and mixed evenly, and the solid content of the mixed slurry is controlled to 35%, and stirred for use;

[0047] Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying at 150° C. for 10 min, and calcining at 450° C. for 3.5 h to obtain a low-temperature NH3-SCR denitration catalyst.

[0048] Example 5

[0049] A low-temperature NH3-SCR denitration catalyst comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier, wherein the coating material comprises, by mass percentage, 30wt% of MnO2, 3wt% of Nd2O3, 5wt% of MoO3, 5wt% of WO3, 2.5wt% of Cr2O3, 2.5wt% of Fe2O3, 40wt% of CeO2 and 22wt% of TiO2; and the coating amount of the coating material is 130g / L.

[0050] The preparation method of the low-temperature NH3-SCR denitration catalyst of this embodiment comprises the following steps:

[0051] Step S1, add 60 parts by weight of a 50% mass fraction manganese nitrate solution to 100 parts by weight of deionized water, then add 5.89 parts by weight of neodymium nitrate hexahydrate, 7.66 parts by weight of ammonium molybdate and 3.67 parts by weight of ammonium metatungstate in sequence, mix and stir evenly, adjust the pH to 3.3 with nitric acid to obtain a clear solution, then add 40 parts by weight of CeO2 powder to the clear solution and continue stirring for 2 hours to obtain a first mixed solution, then add ammonia water dropwise to adjust the pH value of the first mixed solution to 11 to obtain a second mixed solution, and then move the second mixed solution into a hydrothermal reactor for hydrothermal reaction, the hydrothermal reaction temperature is 130°C, the reaction time is 11 hours, after the hydrothermal reaction is completed, filter the second mixed solution, and calcine the filter cake obtained by filtration to obtain Mn-Nd-Mo-W-CeO x Composite oxide, calcination temperature is 500℃, calcination time is 2.5h;

[0052] Step S2: 4.18 parts by weight of ferric nitrate nonahydrate and 7.83 parts by weight of chromium nitrate were added to 80 parts by weight of deionized water in sequence and stirred evenly, and then 73 parts by weight of Mn-Nd-Mo-W-CeO x The composite oxide, 22 parts by weight of titanium oxide powder and 1 part by weight of aluminum sol binder are prepared into a mixed slurry, and the pH value of the mixed slurry is adjusted to 4.5 with nitric acid, and then ground and mixed evenly, and the solid content of the mixed slurry is controlled to 35%, and stirred for standby use;

[0053] Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying at 120° C. for 10 min, and calcining at 550° C. for 2.5 h to obtain a low-temperature NH3-SCR denitration catalyst.

[0054] Example 6

[0055] A low-temperature NH3-SCR denitrification catalyst comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier. Calculated by mass percentage, the coating material comprises 16wt% of MnO2, 2.5wt% of Nd2O3, 4.5wt% of MoO3, 5.5wt% of WO3, 2.4wt% of Cr2O3, 3.6wt% of Fe2O3, 30wt% of CeO2 and 35.5wt% of TiO2; the coating amount of the coating material is 150g / L.

[0056] The preparation method of the low-temperature NH3-SCR denitration catalyst of this embodiment comprises the following steps:

[0057] Step S1, adding 32 parts by weight of a 50% mass fraction manganese nitrate solution to 100 parts by weight of deionized water, then sequentially adding 4.91 parts by weight of neodymium nitrate hexahydrate, 6.89 parts by weight of ammonium molybdate and 8.07 parts by weight of ammonium metatungstate, mixing and stirring evenly, adjusting the pH to 3.0 with nitric acid to obtain a clear solution, then adding 30 parts by weight of CeO2 powder to the clear solution and continuing to stir for 2 hours to obtain a first mixed solution, then dropping ammonia water to adjust the pH value of the first mixed solution to 10.2 to obtain a second mixed solution, and then moving the second mixed solution into a hydrothermal reactor for hydrothermal reaction, the hydrothermal reaction temperature is 130°C, the reaction time is 9 hours, after the hydrothermal reaction is completed, filtering the second mixed solution, and calcining the filter cake obtained by filtration to obtain Mn-Nd-Mo-W-CeO x Composite oxide, calcination temperature is 500℃, calcination time is 3h;

[0058] Step S2: 6.02 parts by weight of ferric nitrate nonahydrate and 7.52 parts by weight of chromium nitrate were added to 80 parts by weight of deionized water in sequence and stirred evenly, and then 58.5 parts by weight of Mn-Nd-Mo-W-CeO x The composite oxide, 35.5 parts by weight of titanium oxide powder and 1 part by weight of aluminum sol binder are prepared into a mixed slurry, and the pH value of the mixed slurry is adjusted to 3.7 with nitric acid, and then ground and mixed evenly, and the solid content of the mixed slurry is controlled to 39%, and stirred for standby use;

[0059] Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying at 120° C. for 15 min, and calcining at 500° C. for 3 h to obtain a low-temperature NH3-SCR denitration catalyst.

[0060] The activity of the catalysts obtained in Examples 1 to 6 was evaluated: the activity evaluation was carried out in a fixed bed reactor, the catalyst volume was 3.375 L, the initial gas concentrations were: NO and NH3 were both 500 ppm, O2 was 6%, H2O was 10%, SO2 content was 200 ppm, and the balance gas was N 2， The reaction space velocity is 6000h -1 The reaction temperatures are 100°C, 120°C, 150°C, 200°C, 250°C and 300°C. The test results are shown in Table 1.

[0061] Table 1 Catalyst activity evaluation results

[0062]

[0063] It can be seen from the test results in Table 1 that the catalysts prepared in Examples 1-6 have a denitration efficiency of 55-100% in the temperature range of 100-300° C. and good activity when co-circulating water.

[0064] The catalysts of Example 1 and Example 6 were tested for water resistance and sulfur resistance. The comparative example was a commercial catalyst. The test of sulfur resistance and water resistance was the same as the activity evaluation device. The initial gas concentration was: NO and NH3 were both 500ppm, O2 was 6%, H2O was 10%, SO2 content was 200ppm, the balance gas was N2, and the reaction space velocity was 6000h -1 The reaction temperature was 150°C. When the reaction time was 2h, H2O and SO2 were introduced into the reaction device. When the reaction time was 10h, the introduction of H2O and SO2 was stopped. The test results are as follows: Figure 1 As shown, from Figure 1 It can be concluded that the catalysts of Examples 1 and 6 of the present invention are significantly better than commercial catalysts in terms of water resistance and sulfur resistance.

[0065] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A low-temperature NH3-SCR denitration catalyst, characterized in that: The invention comprises a cordierite honeycomb ceramic carrier and a coating material coated on the honeycomb ceramic carrier. The coating material comprises, by mass percentage, 10-30 wt% of MnO2, 0-5 wt% of Nd2O3, 0-10 wt% of MoO3, 0-10 wt% of WO3, 0-5 wt% of Cr2O3, 0-5 wt% of Fe2O3, 20-40 wt% of CeO2 and 20-80 wt% of TiO2.

2. The low-temperature NH3-SCR denitration catalyst according to claim 1, characterized in that: The coating amount of the coating material is 50-200 g / L.

3. The method for preparing a low-temperature NH3-SCR denitration catalyst according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step S1, according to the mass percentage of MnO2, Nd2O3, MoO3, WO3 and CeO2, the corresponding manganese precursor, neodymium precursor, molybdenum precursor, tungsten precursor and cerium precursor are weighed, and the manganese precursor is prepared into a precursor solution, and then the manganese precursor solution, the neodymium precursor, the molybdenum precursor and the tungsten precursor are added to deionized water and mixed and stirred evenly, and the pH is adjusted to 3.0-3.5 with nitric acid to obtain a clear solution, and then the cerium precursor is added to the clear solution and stirred for 1-3h to obtain a first mixed solution, and then ammonia water is added dropwise to adjust the pH value of the first mixed solution to 10-11 to obtain a second mixed solution, and then the second mixed solution is moved into a hydrothermal reactor for hydrothermal reaction, and after the hydrothermal reaction is completed, the second mixed solution is filtered, and the filter cake obtained by filtration is calcined to obtain Mn-Nd-Mo-W-CeO x Composite oxides; Step S2: weigh the corresponding chromium precursor, iron precursor and titanium oxide powder according to the mass percentage of Cr2O3, Fe2O3 and TiO2, then add the iron precursor and chromium precursor into deionized water and stir evenly, and then add the Mn-Nd-Mo-W-CeO prepared in step S1 in sequence. x The composite oxide, titanium oxide powder and aluminum sol are stirred evenly to obtain a mixed slurry, the pH value of the mixed slurry is adjusted to 3-5 with nitric acid, and then ground and mixed evenly, the solid content of the mixed slurry is controlled to be 20-50%, and stirred for use; Step S3, coating the mixed slurry obtained in step S2 on a cordierite honeycomb ceramic carrier, drying, and calcining to obtain a low-temperature NH3-SCR denitration catalyst.

4. The method for preparing a low-temperature NH3-SCR denitration catalyst according to claim 3, characterized in that: In step S1, the manganese precursor is selected from one of manganese nitrate, manganese acetate, and manganese chloride; the neodymium precursor is selected from one of neodymium nitrate, neodymium sulfate, neodymium carbonate, neodymium phosphate, neodymium chloride, and neodymium acetate; the molybdenum precursor is selected from molybdic acid or ammonium molybdate; the tungsten precursor is selected from ammonium tungstate or ammonium metatungstate; and the cerium precursor is cerium oxide.

5. The method for preparing a low-temperature NH3-SCR denitration catalyst according to claim 3, characterized in that: The temperature of the hydrothermal reaction in step S1 is 100-150°C, and the reaction time is 8-12 h.

6. The method for preparing a low-temperature NH3-SCR denitration catalyst according to claim 3, characterized in that: In step S1, the calcination temperature is 450-550°C, and the calcination time is 2-4 h.

7. The method for preparing a low-temperature NH3-SCR denitration catalyst according to claim 3, characterized in that: In step S2, the iron precursor is selected from one of ferric nitrate, ferric sulfate, ferric chloride, and ferric acetate; and the chromium precursor is selected from one of chromium nitrate, chromium carbonate, and chromium chloride.

8. The method for preparing a low-temperature NH3-SCR denitration catalyst according to claim 3, characterized in that: In step S3, the drying temperature is 120°C-150°C, and the drying time is 5-15 min.

9. The method for preparing a low-temperature NH3-SCR denitration catalyst according to claim 3, characterized in that: In step S3, the calcination temperature is 450-550°C, and the calcination time is 2-4 hours.

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