Micron-spherical cerium-manganese-based composite oxide and method for preparing the same

Abstract

This invention aims to provide a micron-sized spherical cerium-manganese-based composite oxide and its preparation method, characterized in that the particle size of the cerium-manganese-based composite oxide is in the range of 2–4 μm, and the specific surface area is in the range of 10⁸–13² m². 2 Within the range of / g; the molar ratio of Ce to Mn is 1:6 to 8, and the molar ratio of the doped co-catalytic metal element to Ce is (0.1 to 1.5):1. The main preparation process involves dissolving cerium, manganese, and the metal salt of the dopant element in a polyol to prepare a mixed solution, carrying out a hydrothermal reaction in a reactor, collecting the precipitate by centrifugation, and then obtaining micron-sized spherical cerium-manganese-based composite oxides through washing, drying, and calcination. The specific surface area of ​​this cerium-manganese-based composite oxide is 108 to 132 m². 2 / g, capable of efficiently removing NO by NH3-SCR within the range of 54–275℃. x It maintains a denitrification efficiency of over 99% for a long time under a high-humidity sulfur-containing atmosphere at 127℃, making it particularly suitable for deep denitrification of complex flue gas with high humidity and sulfur content after desulfurization and dust removal in non-power industries.

Description

Technical Field

[0001] This invention provides a micron-sized spherical cerium-manganese-based composite oxide with ultra-low temperature denitrification activity and strong resistance to water sulfur poisoning, and its preparation method. It belongs to the fields of materials synthesis and processing, environmental catalytic materials and air pollution control. The micron-sized spherical cerium-manganese-based composite oxide is mainly used for ultra-low temperature deep denitrification of complex flue gas with high humidity and sulfur content after desulfurization and dust removal in non-power industries. Technical Background

[0002] NO x It is the formation of PM 2.5 Air pollutants are important precursors to smog, ozone, and acid rain, severely deteriorating the atmospheric environment and endangering human health, making them a key focus of air pollution prevention and control. Following the achievement of NOx emission reduction targets in the thermal power industry... x After achieving ultra-low emissions, non-power sectors have become the leading industrial NOx emission standard. x As a major source of emissions, deep denitrification has become a key challenge for non-power industries to achieve green and high-quality development. Due to the diverse categories of non-power industries and the varying and complex flue gas conditions, existing commercial denitrification catalysts are difficult to directly apply to the complex flue gas denitrification processes of these industries. However, the complex flue gas emitted by most non-power industries, after desulfurization and dust removal treatment, exhibits common operating characteristics: extremely low flue gas temperature (≤150℃), high moisture content (≥5%), and low concentrations of SO2 (<35mg / Nm³). 3 Currently, low-temperature denitrification catalysts under development can achieve efficient denitrification below 150℃. However, under the aforementioned high-humidity, sulfur-containing atmospheres, their ultra-low-temperature denitrification efficiency drops significantly or even fails; while actual denitrification projects typically employ post-heating to 200-220℃ for low-temperature denitrification, resulting in high energy consumption and operating costs. Therefore, developing ultra-low-temperature, high-efficiency denitrification catalysts with strong resistance to water sulfur poisoning has become crucial for non-power industries to achieve NO reduction. x The urgent need for ultra-low emissions and the challenge of overcoming sulfur poisoning in water at ultra-low temperatures are recognized global problems in the field of denitrification.

[0003] In current research on ultra-low temperature denitrification catalysts, cerium-manganese composite oxides have become a research hotspot due to their ability to achieve highly efficient NH3-SCR denitrification at temperatures below 150℃. However, their poor resistance to water and sulfur poisoning at ultra-low temperatures urgently needs improvement. Several patents and literature reports have been published on ultra-low temperature denitrification catalysts both domestically and internationally. Domestic patent CN 107570142 A discloses a low-temperature denitrification catalyst and its preparation method. This involves a hydrothermal reaction of graphene oxide and nitrogen-containing substances to obtain nitrogen-doped graphene, followed by the addition of metal salts such as manganese, iron, vanadium, and tungsten, and titanium dioxide, and then another hydrothermal reaction. The resulting powder is calcined under a protective gas atmosphere to obtain the ultra-low temperature denitrification catalyst, which exhibits good activity at 120-180℃, but its resistance to water and sulfur has not been investigated. CN 109718767 B discloses a ruthenium-based ultra-low temperature denitrification catalyst, prepared by a segmented impregnation method and calcination. It consists of a denitrification active component and a support, wherein the denitrification active component includes cerium oxide, manganese oxide, and ruthenium oxide, and the support is titanium dioxide. The denitrification efficiency is above 90% in the range of 135–165 °C, exhibiting a narrow denitrification activity temperature range; however, its stability and resistance to water and sulfur dioxide were not investigated. Furthermore, the paper [Chemical Engineering Journal, 2017, 317: 20-31] describes a Co1Mn4Ce5O catalyst prepared by a co-precipitation method. x At 48000h -1 NO at air velocity within 80~175℃ x The conversion rate reached over 90%. The paper [ACS Applied Materials & Interfaces, 2017, 19: 16117] describes the synthesis of porous nanoneedle-structured MnO using a hydrothermal method. x -FeO x Catalyst at 36000h -1 NO at airspeed within 120~240°C xThe conversion rate can reach 100%. US 20210187490 A1 proposes a low-temperature denitrification catalyst for selective catalytic reduction and its preparation method. The catalyst prepared by co-precipitation method with bismuth, cerium, and titanium precipitates is dried and heat-treated, and then impregnated with vanadium and tungsten as supports. After SO2 is introduced, the denitrification activity can reach more than 80% at 100~300℃, but the water resistance is not investigated and the preparation process is complex. US 7820583 B2 prepares nanocomposite particles by hydrothermal method. The nanocomposite particles include titanium dioxide nanoparticles, metal oxide nanoparticles and surfactants. The denitrification efficiency reaches 91% at 320℃, but the denitrification activity is poor when tested only at this temperature, and the anti-poisoning performance is not described. Most of the above catalysts can only show good low-temperature denitrification performance under conditions without SO2 and water vapor, and the activity temperature window is narrow. The denitrification effect is not ideal under high humidity and sulfur-containing ultra-low temperature conditions, and they do not have the stability for long-term operation, making it difficult to meet the needs of practical engineering applications. Therefore, the development of highly efficient denitrification catalysts with strong resistance to water and sulfur at ultra-low temperatures has become a major demand for the denitrification of complex flue gas in non-power industries. Summary of the Invention

[0004] The purpose of this invention is to address the problem that existing ultra-low temperature denitrification catalysts are prone to poisoning and failure under high humidity and sulfur-containing atmospheres, resulting in poor operational stability and inability to meet practical engineering applications. This invention provides a micron-sized spherical cerium-manganese-based composite oxide. Another objective is to provide a method for preparing the aforementioned micron-sized spherical cerium-manganese-based composite oxide. This patent achieves the goal of enhancing the ultra-low temperature resistance to water-sulfur poisoning of the cerium-manganese-based composite oxide through two aspects: firstly, by modifying it with co-catalytic elements such as Fe, Co, Cu, Ni, or Sn; and secondly, by synthesizing micron-sized spherical particles through a method for controlling its microstructure. Based on these two aspects, it aims to enhance the ultra-low temperature resistance of the cerium-manganese-based composite oxide to water-sulfur poisoning, striving to provide key technical support for the denitrification of complex flue gas with high humidity and sulfur content after desulfurization and dust removal in non-power industries.

[0005] The technical solution of this invention is: a micron-sized spherical cerium-manganese-based composite oxide, characterized in that the particle size of the cerium-manganese-based composite oxide is in the range of 2~4μm, and the specific surface area is in the range of 108~132m². 2 Within the range of / g; where the molar ratio of Ce to Mn is 1:6~8, and the molar ratio of the doped co-catalytic metal element to Ce is (0.1~1.5):1.

[0006] Preferably, the doped co-catalytic metal element is Fe, Co, Cu, Ni or Sn.

[0007] This invention also provides a method for preparing the above-mentioned micron-sized cerium-manganese-based composite oxide, the specific steps of which are as follows:

[0008] (1) Preparation of precursor mixed solution

[0009] According to the molar ratio of doped cocatalytic metal element, Ce and Mn, different masses of doped cocatalytic metal element salt, cerium salt and manganese salt reagents are weighed and added to alcohol solvent to dissolve and stir to mix evenly to obtain a mixed solution; the polyol solvent mentioned is any one or two of methanol, ethanol, ethylene glycol, isopropanol or glycerol.

[0010] (2) Preparation of cerium-manganese-based composite oxides

[0011] The mixed solution obtained in step (1) was transferred to a reaction vessel for hydrothermal reaction. The precipitate was then collected by centrifugation and washed until the supernatant was clear. The resulting sample was then vacuum dried and calcined to obtain micron-sized spherical cerium-manganese-based composite oxides.

[0012] The preferred step (2) is to use one of Fe, Co, Cu, Ni or Sn; the cerium salt, manganese salt and the doped catalytic metal element salt are all one of nitrate, chloride, acetate or sulfate.

[0013] The preferred hydrothermal reaction temperature in step (2) is 140~200℃, and the hydrothermal reaction time is 12~16h.

[0014] The preferred drying temperature in step (2) is 60~100℃ and the drying time is 10~16h.

[0015] In step (2), the preferred roasting temperature is 300-500℃ and the roasting time is 2-5h. The roasting atmosphere is air.

[0016] Evaluation of the NH3-SCR denitrification effect of the prepared samples:

[0017] Measure 1.8 ml of sample with a particle size of 20-40 mesh and place it into a fixed-bed quartz reaction tube with an inner diameter of 8 mm. Simulate typical flue gas composition in non-electric industries: inlet NO and NH3 concentrations of 1000 ppm, O2 content of 10 vol.%, SO2 concentration of 50 ppm, and water content of 5 vol.%, using N2 as the balance gas, and setting the reaction space velocity (GHSV) to 20000 h⁻¹. -1 The reaction temperature was set at 54~275℃, and a flue gas analyzer (MRU VarioPlus, Germany) was used to monitor NO, NO2, and NO at the reactor inlet and outlet online. x The concentration.

[0018] Beneficial effects:

[0019] The micron-sized cerium-manganese-based composite oxide in this invention is prepared by a wet chemical method, giving it a large specific surface area (10⁸~132 m²). 2(g) and abundant oxygen vacancies, with particle sizes ranging from 2 to 4 μm. NH3-SCR can remove NO within the temperature range of 54–275 °C. x The efficiency is >91%, exhibiting a wide denitrification temperature range. Furthermore, after 30 hours of efficient and stable operation in a high-humidity, sulfur-containing atmosphere at 127℃, the denitrification activity does not decrease, unaffected by water vapor or SO2 atmosphere. Compared to existing ultra-low temperature denitrification catalysts, the cerium-manganese-based composite oxide developed by this invention exhibits higher ultra-low temperature denitrification activity, a wider temperature window, and stronger resistance to water and sulfur poisoning. It is particularly suitable for deep denitrification of complex flue gas containing sulfur at ultra-low temperatures in non-power industries such as non-ferrous metals and chemicals. Attached Figure Description

[0020] Figure 1 Fe1Ce1Mn prepared in Example 5 of this invention 7.5 O x NO removal at 127℃ with prolonged exposure to 50ppm SO2 and 5vol% H2O x Efficiency diagram;

[0021] Figure 2 Fe1Ce1Mn prepared in Example 5 of this invention 7.5 O x SEM and EDX mapping images of microscopic particles. Detailed Implementation

[0022] Example 1:

[0023] Measure 50 ml of ethanol and 5 ml of glycerol and place them in a 100 ml beaker. Weigh 0.024 g of ferric chloride, 0.651 g of cerium nitrate, and 1.687 g of manganese acetate according to a Fe / Ce / Mn molar ratio of 0.1:1:6.5, and add them to the above solution. Stir continuously for 1.2 h to obtain a mixed solution. Transfer the mixed solution B to a 100 ml reactor and carry out a hydrothermal reaction at 160 °C for 12 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 80 °C for 12 h and calcined at 350 °C for 4 h to obtain cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder. The catalyst is named Fe... 0.1 Ce1Mn 6.5 O x The catalyst has a particle size of 3.7 μm and a specific surface area of ​​123 m². 2 / g, the denitrification performance of Example 1 is shown in Table 1.

[0024] Example 2:

[0025] Measure 8 ml of glycerol and 40 ml of isopropanol and place them in a 100 ml beaker and stir. Weigh 0.0182 g of ferric nitrate, 0.370 g of cerium chloride, and 1.800 g of manganese sulfate according to a Fe / Ce / Mn molar ratio of 0.3:1:7.1, and add them to the above solution. Stir continuously for 1 h to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and carry out a hydrothermal reaction at 180 °C for 13 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 60 °C for 16 h and calcined at 400 °C for 2 h to obtain cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder. The catalyst is named Fe... 0.3 Ce1Mn 7.1 O x The catalyst has a particle size of 2.4 μm and a specific surface area of ​​10⁸ m². 2 / g, the denitrification performance of Example 2 is shown in Table 1.

[0026] Example 3:

[0027] Measure 60 ml of ethylene glycol and place it in a 100 ml beaker. Weigh 0.130 g of ferric acetate, 0.498 g of cerium sulfate, and 1.284 g of manganese chloride according to a Fe / Ce / Mn molar ratio of 0.5:1:6.8, and add them to the above solution. Stir continuously for 1.2 h to obtain a mixed solution. Transfer mixed solution B to a 100 ml reactor and carry out a hydrothermal reaction at 140 °C for 15 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 100 °C for 12 h and calcined at 450 °C for 3 h to obtain cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder. The catalyst is named Fe... 0.5 Ce1Mn 6.8 O x The catalyst has a particle size of 3.5 μm and a specific surface area of ​​116 m². 2 / g, the denitrification performance of Example 3 is shown in Table 1.

[0028] Example 4:

[0029] Measure 7 ml of glycerol and 49 ml of isopropanol and place them in a 100 ml beaker. Weigh out 0.480 g of ferric sulfate, 0.370 g of cerium chloride, and 4.026 g of manganese nitrate according to a Fe / Ce / Mn molar ratio of 0.8:1:7.5, and add them to the above solution. Stir continuously for 1.4 h to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and carry out a hydrothermal reaction at 150 °C for 14 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 90 °C for 10 h and calcined at 300 °C for 3 h to obtain cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder. The catalyst is named Fe... 0.8 Ce1Mn 7.5 O x The catalyst has a particle size of 2.8 μm and a specific surface area of ​​118 m². 2 / g, the denitrification performance of Example 4 is shown in Table 1.

[0030] Example 5:

[0031] Measure 45 ml of ethanol and 10 ml of isopropanol and place them in a 100 ml beaker. Weigh out 0.606 g of ferric nitrate, 0.476 g of cerium acetate, and 3.758 g of manganese nitrate according to a Fe / Ce / Mn molar ratio of 1:1:7, and add them to the above solution. Stir continuously for 1 hour to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and carry out a hydrothermal reaction at 180 °C for 13 hours. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 80 °C for 13 hours and calcined at 400 °C for 3 hours to obtain the cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder, named Fe1Ce1Mn7O. x The denitrification performance of Example 5 is shown in Table 1. The table shows that the denitrification rate is >91% at 54~275℃. Figure 1 As can be seen, in the long-term water-sulfur stability test at 127°C, Example 5 was unaffected by water-sulfur, exhibiting excellent resistance to water-sulfur poisoning at ultra-low temperatures. The catalyst has a specific surface area of ​​132 m². 2 / g, from Figure 2 As can be seen from the SEM image, Example 5 is mainly spherical with a particle size of 3.3 μm. As can be seen from the EDX mapping image, all elements (Fe, Mn, Ce, O) are uniformly distributed throughout the micron-sized spherical structure.

[0032] Example 6:

[0033] Measure 60 ml of ethylene glycol and 10 ml of isopropanol and place them in a 100 ml beaker. Weigh out 0.900 g of ferric sulfate, 0.651 g of cerium nitrate, and 2.643 g of manganese chloride according to a Fe / Ce / Mn molar ratio of 1.5:1:7, and add them to the above solution. Stir continuously for 1.1 h to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and carry out a hydrothermal reaction at 170 °C for 14 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 70 °C for 14 h and calcined at 400 °C for 3 h to obtain cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder. The catalyst is named Fe... 1.5 Ce1Mn7O x The catalyst has a particle size of 3.6 μm and a specific surface area of ​​126 m². 2 / g, the denitrification performance of Example 6 is shown in Table 1.

[0034] Example 7:

[0035] Measure 60 ml of methanol and place it in a 100 ml beaker. Weigh out 0.391 g of tin chloride, 0.651 g of cerium nitrate, and 1.472 g of manganese chloride according to a Sn / Ce / Mn molar ratio of 1:1:7.8, and add them to the above-mentioned well-stirred solution. Stir continuously for 1 h to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and carry out a hydrothermal reaction at 200 °C for 12 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum-dried at 90 °C for 14 h and calcined at 400 °C for 3 h to obtain the cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder, named Sn1Ce1Mn. 7.8 O x The catalyst has a particle size of 2.9 μm and a specific surface area of ​​110 m². 2 / g, the denitrification performance of Example 7 is shown in Table 2.

[0036] Example 8:

[0037] Measure 7 ml of glycerol and 49 ml of isopropanol and place them in a 100 ml beaker. Weigh out 0.437 g of cobalt nitrate, 0.651 g of cerium nitrate, and 1.510 g of manganese chloride according to a Co / Ce / Mn molar ratio of 1:1:8, and add them to the above solution. Stir continuously for 1.5 h to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and perform a hydrothermal reaction at 180 °C for 16 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 100 °C for 10 h and calcined at 450 °C for 3 h to obtain the cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder, named Co1Ce1Mn8O. x The catalyst has a particle size of 2 μm and a specific surface area of ​​112 m². 2 / g, the denitrification performance of Example 8 is shown in Table 2.

[0038] Example 9:

[0039] Measure 50 ml of ethanol and place it in a 100 ml beaker. Weigh out 0.436 g of nickel nitrate, 0.651 g of cerium nitrate, and 1.265 g of manganese chloride according to a Ni / Ce / Mn molar ratio of 1:1:6.7, and add them to the above solution. Stir continuously for 1.2 h to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and carry out a hydrothermal reaction at 190 °C for 12 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 90 °C for 14 h and calcined at 350 °C for 5 h to obtain the cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder, named Ni1Ce1Mn6.7O. x The catalyst has a particle size of 3.4 μm and a specific surface area of ​​128 m². 2 / g, the denitrification performance of Example 9 is shown in Table 2.

[0040] Example 10:

[0041] Measure 8 ml of glycerol and 40 ml of methanol and place them in a 100 ml beaker. Weigh out 0.362 g of copper nitrate, 0.651 g of cerium nitrate, and 1.895 g of manganese acetate according to a Cu / Ce / Mn molar ratio of 1:1:7.3, and add them to the above solution. Stir continuously for 1.2 h to obtain a mixed solution. Transfer the mixed solution to a 100 ml reactor and perform a hydrothermal reaction at 160 °C for 12 h. Then, centrifuge (12000 rpm, 5 min) to collect the precipitate and wash until the supernatant is clear. The obtained sample is then vacuum dried at 70 °C for 15 h and calcined at 500 °C for 3 h to obtain the cerium-manganese-based composite oxide ultra-low temperature denitration catalyst powder, named Cu1Ce1Mn. 7.3O x The catalyst has a particle size of 2.9 μm and a specific surface area of ​​126 m². 2 / g, the denitrification performance of Example 10 is shown in Table 2.

[0042] Table 1. Denitrification rates of the catalysts prepared in Examples 1-6

[0043] active / % Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 54℃ 76.51% 75.23% 77.52% 84.81% 91.70% 70.45% 59℃ 82.32% 80.67% 84.68% 92.90% 92.25% 87.35% 64℃ 90.15% 81.92% 86.80% 97.82% 97.16% 93.68% 69℃ 90.16% 89.98% 94.77% 99.43% 99.13% 86.86% 75℃ 98.67% 97.82% 98.80% 99.53% 99.89% 89.82% 81℃ 98.63% 99.89% 97.49% 99.62% 99.89% 97.63% 87℃ 98.54% 99.89% 99.02% 99.62% 99.89% 99.41% 107℃ 99.15% 99.89% 99.89% 99.81% 99.89% 99.51% 127℃ 99.89% 99.89% 99.89% 99.81% 100.00% 99.60% 149℃ 99.89% 99.78% 99.89% 99.81% 99.89% 99.60% 170℃ 99.89% 99.89% 99.89% 99.81% 99.89% 93.58% 190℃ 99.58% 99.89% 99.89% 99.81% 100.00% 89.92% 210℃ 98.94% 99.89% 99.89% 99.81% 100.00% 87.06% 232℃ 98.30% 99.78% 99.78% 99.81% 99.89% 88.54% 255℃ 95.86% 98.69% 99.35% 99.53% 99.78% 83.10% 275℃ 88.22% 88.34% 87.58% 80.61% 95.52% 77.27%

[0044] Table 2. Denitrification rates of the catalysts prepared in Examples 7-10

[0045] active / % Example 7 Example 8 Example 9 Example 10 54℃ 82.52% 85.23% 77.52% 80.82% 59℃ 90.32% 91.67% 90.68% 88.90% 64℃ 96.18% 97.92% 96.80% 93.83% 69℃ 99.16% 99.98% 99.77% 99.13% 75℃ 99.67% 99.85% 99.80% 99.53% 81℃ 99.63% 99.89% 99.49% 99.62% 87℃ 99.54% 99.89% 99.02% 99.62% 107℃ 99.15% 99.89% 99.89% 99.81% 127℃ 99.89% 99.89% 99.89% 99.81% 149℃ 99.89% 99.78% 99.89% 99.81% 170℃ 99.89% 99.89% 99.89% 99.81% 190℃ 99.58% 99.89% 99.89% 99.81% 210℃ 98.94% 99.89% 99.89% 99.81% 232℃ 98.35% 99.78% 99.78% 99.81% 255℃ 95.45% 98.69% 99.35% 99.53% 275℃ 88.22% 88.35% 86.59% 80.61%

[0046] As can be seen from Table 1-2, the Fe1Ce1Mn7O prepared in Example 5... x The catalyst exhibits highly efficient ultra-low temperature SCR denitrification activity.

Claims

1. A micron-sized spherical cerium-manganese-based composite oxide, characterized in that... The particle size of cerium-manganese-based composite oxides ranges from 2 to 4 μm, and the specific surface area ranges from 10⁸ to 132 m². 2 Within the range of / g; wherein the molar ratio of Ce to Mn is 1:6~8, and the molar ratio of the doped co-catalytic metal element to Ce is (0.1~1.5):1; the doped co-catalytic metal element is Fe, Co, Cu, Ni or Sn.

2. A method for preparing the micron-sized cerium-manganese-based composite oxide as described in claim 1, comprising the following specific steps: (1) Preparation of precursor mixed solution According to the molar ratio of the doped cocatalytic metal element and Ce to Mn, different masses of doped cocatalytic metal element salts, cerium salts and manganese salts were weighed and added to an alcohol solvent to dissolve and stir until homogeneous to obtain a mixed solution; wherein the doped cocatalytic metal element is one of Fe, Co, Cu, Ni or Sn; the alcohol solvent is any one or two of methanol, ethanol, ethylene glycol, isopropanol or glycerol. (2) Preparation of cerium-manganese-based composite oxides The mixed solution obtained in step (1) is transferred to a reaction vessel for hydrothermal reaction. The precipitate is then collected by centrifugation and washed until the supernatant is clear. The obtained sample is then vacuum dried and calcined to obtain micron-sized spherical cerium-manganese-based composite oxides. The hydrothermal reaction temperature is 140~200℃ and the hydrothermal reaction time is 12~16h.

3. The method according to claim 2, characterized in that... The cerium salt, manganese salt, and doped co-catalytic metal element salt mentioned in step (1) are all one of nitrate, chloride, acetate, or sulfate.

4. The method according to claim 2, characterized in that... In step (2), the drying temperature is 60~100℃ and the drying time is 10~16h.

5. The method according to claim 2, characterized in that... In step (2), the roasting temperature is 300~500℃ and the roasting time is 2~5h.

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