A rare earth manganese zirconium composite compound doped with grain boundaries and surfaces, its preparation method and application

Abstract

This invention relates to a grain boundary and surface-doped rare-earth manganese-zirconium composite compound, its preparation method, and its applications. By using a grain boundary doping method, rare-earth manganese oxides with special structures are formed at the grain boundaries and surfaces of rare-earth zirconium-based oxides. This increases oxygen defects at the grain boundaries and surfaces, thereby increasing the amount of active oxygen and enhancing the catalytic activity of the rare-earth manganese-zirconium composite compound, inhibiting its high-temperature sintering, and improving its ability to catalytically oxidize NO. Applying this rare-earth manganese-zirconium composite compound to catalysts can significantly reduce the amount of precious metals required.

Description

Technical Field

[0001] This invention relates to the field of rare earth manganese zirconium composite compounds, and more particularly to a rare earth manganese zirconium composite compound doped with grain boundaries and surfaces, its preparation method, and its applications. Background Technology

[0002] Lean-burn engines (such as diesel and lean-burn gasoline engines) are widely used due to their high fuel economy and low greenhouse gas emissions; however, they produce large amounts of nitrogen oxides (NOx) in their exhaust gases. x NO not only causes prominent environmental problems such as photochemical smog and acid rain, but also poses serious threats to human health. Therefore, how to effectively remove NO from lean-burn engine exhaust is crucial. x This is currently a hot research topic both domestically and internationally. DOC (Digital Oxide Catalyst) is an oxidation catalyst used in diesel engines to reduce nitrogen oxides (NOx) in diesel engines. x Hydrocarbons (HC) and carbon monoxide (CO) are gaseous pollutants. Currently, DOC (densityly oxidized carbon) is typically achieved by using alumina supported on noble metals to oxidize HC, CO, and some NO. However, the NO→NO2 oxidation rate is usually below 40%. To obtain higher NO oxidation performance, more noble metals need to be coated, resulting in a significant increase in catalyst cost. Metal oxide catalysts are not only low-cost but also have good catalytic activity, and have attracted much attention in recent years, such as Cu-Cr(Co) and MnO. x The composite oxides of CeO2 and CuMnO4 are beneficial for diesel soot and NO oxidation, but metal oxides generally have poor temperature resistance and are prone to deactivation at high temperatures. Therefore, it is urgent to develop new catalytic materials with high NO catalytic activity and high temperature stability. Summary of the Invention

[0003] Based on the above-mentioned situation of the prior art, the purpose of the present invention is to provide a rare earth manganese zirconium composite compound doped with grain boundaries and surface, its preparation method and application, which significantly enhances the oxidation ability of metal ions at the surface and grain boundaries, inhibits the deactivation of active components during high-temperature sintering, and improves the catalytic oxidation ability of NO through doping.

[0004] To achieve the above objectives, according to one aspect of the present invention, a rare-earth manganese-zirconium composite compound doped at grain boundaries and surfaces is provided, the chemical formula of the rare-earth manganese-zirconium composite compound being RE. a Mn b Zr c L d M e O (2-δ) D β RE represents rare earth elements; M and L represent cation doping elements; and D represents anion doping elements.

[0005] Where, 0.1≤a≤0.5, 0.05≤b≤0.4, 0.2≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, 0≤δ≤0.1, 0≤β≤0.1, a+b+c+d+e=1.

[0006] Furthermore, the rare earth manganese zirconium composite compound contains one or more of the doping elements M, L, and D at its grain boundaries and surface.

[0007] Furthermore, the doping elements M, L, and D are in the form of one or more of oxides, nitrogen-containing compounds, fluorides, phosphates, and sulfates at the grain boundaries and surface of the rare earth manganese zirconium composite oxide.

[0008] Furthermore, the RE includes one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Ho, Er, Tm, Yb, Lu, Y and Sc;

[0009] Preferably, RE is one or more of La, Ce, Pr, Nd, Sm, Eu, Gd and Y.

[0010] Furthermore, the cation doping element M includes one or more combinations of Fe, Ni, Co, Cu, Zn, V, Ti, Cr, Mo, W, Sn, and Nb; the cation doping element L includes one or more combinations of Al, Si, Hf, Ba, Sr, Mg, and Ca; and the doping element D includes one or more combinations of anions N, P, F, and S.

[0011] Furthermore, the total amount of +3 and +4 valence states of Mn at the surface and grain boundaries of the rare earth manganese zirconium composite compound accounts for more than 80% of all Mn valence states; preferably, more than 90%.

[0012] According to a second aspect of the present invention, a method for preparing a grain boundary and surface-doped rare-earth manganese-zirconium composite compound as described in the first aspect of the present invention is provided, comprising the following steps:

[0013] S1. Mix the required stoichiometric ratio of a mixed salt aqueous solution of Zr and RE or a mixed salt aqueous solution of Zr, RE and L with an alkaline solution to carry out a precipitation reaction. After filtration, washing, drying and calcination, a rare earth zirconium-based oxide containing RE and L is obtained.

[0014] S2. Mix the required stoichiometric amount of a mixed salt solution of Mn and RE or a mixed salt solution of Mn, RE and M with the rare earth zirconium-based oxide obtained in step S1 to obtain a wet composite compound.

[0015] S3. Perform one or two heat treatments on the wet composite compound material obtained in step S2.

[0016] S4. The material obtained in step S3 is subjected to one or two calcination processes to obtain rare earth manganese zirconium composite compounds doped with grain boundaries and surfaces.

[0017] Furthermore, dopant element D is added in one or both of steps S1 and S2; dopant element D is added in one or more combinations of nitrate, fluoride, phosphate and sulfate, preferably in one or more combinations of nitrate and sulfate.

[0018] Furthermore, the manganese source in the mixed salt aqueous solution of steps S1 and S2 includes one or more combinations of chlorides, nitrates, sulfates and acetates, preferably manganese nitrate; the zirconium source includes one or more combinations of chlorine oxides, nitrates, sulfates, acetates and citrates, preferably zirconium oxynitrate; the M, L and RE salt aqueous solutions include one or more combinations of liquid salts of chlorides, nitrates, sulfates, acetates, citrates and amino acid salts, and organosilicon compounds, preferably nitrates.

[0019] Furthermore, the alkaline solution in step S1 includes magnesium bicarbonate, urea, and at least one of hydroxides, carbonates, and bicarbonates of at least one element selected from ammonium, sodium, and potassium, preferably at least one of sodium hydroxide, urea, ammonia, and ammonium bicarbonate.

[0020] Furthermore, during the precipitation process in step S1, the pH value is controlled at 4.5-14, preferably 5-11; the pH value at the precipitation endpoint is controlled at 8-13, preferably 9-11; and the temperature during the precipitation process is 0-120℃, preferably 20-80℃.

[0021] Furthermore, in step S1, the calcination temperature of the rare earth zirconium-based oxide is 500-1000℃, and the time is 1-20 hours; preferably, the calcination temperature is 600℃-900℃, and the time is 2-10 hours.

[0022] Furthermore, in step S3, the heat treatment temperature is 100-500℃ and the time is 2-30h; preferably, the heat treatment temperature is 150-300℃ and the time is 6-12h.

[0023] Furthermore, in step S4, the calcination temperature is 400-1000℃ and the time is 1-20 hours; preferably, the calcination temperature is 500℃-900℃ and the time is 3-10 hours.

[0024] Furthermore, the particle size D50 of the post-processed rare earth manganese zirconium composite compound is less than 15 μm, preferably less than 10 μm.

[0025] Furthermore, after calcination, rare earth manganese oxides containing perovskite, spinel, or mullite structures are formed on the surface and at the grain boundaries of the rare earth zirconium-based oxides.

[0026] According to a third aspect of the present invention, the application of grain boundary and surface doped rare earth manganese zirconium composite compounds as described in the first aspect of the present invention is provided in the fields of motor vehicle exhaust purification, industrial waste gas treatment and catalytic combustion.

[0027] In summary, this invention provides a rare-earth manganese-zirconium composite compound doped at grain boundaries and surfaces, its preparation method, and its applications. By doping rare-earth elements, manganese, and transition metals are added to the surface, grain boundaries, and interior of rare-earth zirconium-based oxides, resulting in rare-earth manganese-zirconium composite compounds containing perovskite, spinel, and mullite structures. On one hand, this allows the compounds formed by rare-earth elements, manganese, and transition metals to have their phase structure transformation suppressed by the rare-earth zirconium-based oxides at high temperatures, thus improving their high-temperature catalytic activity. On the other hand, it facilitates the diffusion of free active oxygen from the rare-earth zirconium-based oxides at the surface and grain boundaries to the active sites, further enhancing the catalytic activity of the rare-earth manganese-zirconium composite compound. The technical solution of this invention significantly enhances the oxidation capacity of metal ions at the surface and grain boundaries through grain boundary and surface doping, inhibits the high-temperature sintering deactivation of active components, and improves the catalytic oxidation capacity of NO. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the preparation method of rare earth manganese zirconium composite compounds doped at the surface and grain boundaries according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0030] According to a first aspect of the present invention, a grain boundary and surface-doped rare-earth manganese-zirconium composite compound is provided, the chemical formula of the rare-earth manganese-zirconium composite compound being RE. a Mn b Zr c L d M e O (2-δ) D βRE represents rare earth elements; M and L represent cation doping elements, and D represents anion doping elements; the values ​​of each element can be: 0.1≤a≤0.5, 0.05≤b≤0.4, 0.2≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, 0≤δ≤0.1, 0≤β≤0.1, and a+b+c+d+e=1.

[0031] The element RE can be one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc; preferably, RE is one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, and Y; the dopant element M can be one or more of Fe, Ni, Co, Cu, Zn, V, Ti, Cr, Mo, W, Sn, and Nb, with the molar percentage of element M at grain boundaries and surfaces being 10%-70%; the dopant element L can be one or more of Al, Si, Hf, Ba, Sr, Mg, and Ca, with the molar percentage of element L at grain boundaries and surfaces being 10%-70%; the dopant element D can be one or more of anions N, P, F, and S, with the molar percentage of element D at grain boundaries and surfaces being 10%-70%. The morphology and proportion of L, M, and D at grain boundaries and surfaces can be controlled by adjusting precipitation parameters, heat treatment temperature of the product, calcination temperature, time, and atmosphere.

[0032] The rare earth manganese zirconium composite compound contains one or more of the doping elements M, L and D at its grain boundaries and surface.

[0033] The doping elements M, L, and D are in the form of one or more of oxides, nitrogen-containing compounds, fluorides, phosphates, and sulfates at the grain boundaries and surface of the rare earth manganese zirconium composite oxide.

[0034] The total amount of +3 and +4 valence states of element Mn at the surface and grain boundaries of this rare earth manganese zirconium composite compound accounts for more than 80% of all Mn valence states; preferably, more than 90%.

[0035] According to a second aspect of the present invention, a method for preparing a surface- and grain-bound rare-earth manganese-zirconium composite compound as described in the first aspect of the present invention is provided. Figure 1 The flowchart of the preparation method is shown, including the following steps:

[0036] S1. A mixed salt aqueous solution of Zr and RE in the required stoichiometric ratio, or a mixed salt aqueous solution of Zr, RE, and L, is mixed with an alkaline solution to carry out a precipitation reaction. After filtration, washing, drying, and calcination, rare earth zirconium-based oxides containing RE and L are obtained. During precipitation, the pH value is controlled at 4.5-14, preferably 5-11; the final pH value is controlled at 8-13, preferably 9-11; the temperature during precipitation is 0-120℃, preferably 20-80℃. The calcination conditions are maintained at 500-1000℃ for 1-20 hours; preferably at 600℃-900℃ for 2-10 hours. A dopant element D can be added in step S1. The dopant element D is added, for example, through one or more combinations of nitrates, fluorides, phosphates, and sulfates, preferably through one or more combinations of nitrates and sulfates. The alkaline solution can be at least one of magnesium bicarbonate, urea, and hydroxides, carbonates, and bicarbonates of at least one of ammonium, sodium, and potassium, preferably at least one of sodium hydroxide, urea, ammonia, and ammonium bicarbonate.

[0037] S2. Mix the required stoichiometric amount of a mixed salt solution of Mn and RE or a mixed salt solution of Mn, RE and M with the rare earth zirconium-based oxide obtained in step S1 to obtain a wet composite compound. Alternatively, a dopant element D can be added in step S2. The dopant element D can be added, for example, by one or more of nitrates, fluorides, phosphates and sulfates, preferably by one or more of nitrates and sulfates.

[0038] The manganese source in the mixed salt solution of steps S1 and S2 includes one or more of chlorides, nitrates, sulfates and acetates, preferably manganese nitrate; the zirconium source includes one or more of chlorine oxides, nitrates, sulfates, acetates and citrates, preferably zirconium oxynitrate; the M, L and RE salt solutions include one or more of liquid salts of chlorides, nitrates, sulfates, acetates, citrates and amino acid salts, and organosilicon compounds, preferably nitrates.

[0039] S3. The wet composite compound obtained in step S2 is subjected to one or two heat treatments; the heat treatment temperature is, for example, 100-500℃, and the time is 2-30h; preferably, the heat treatment temperature is 150-300℃, and the time is 6-12h. In order to meet the special requirements of different applications for rare earth manganese zirconium composite compounds, it is necessary to adjust or change the type of doping elements and the microstructure at the grain boundaries, which requires different heat treatment regimes, such as step-by-step heat treatment, so that more doping elements can enter the grain boundaries more uniformly and stably. Water washing, water quenching, etc. can also be performed between the two heat treatment steps.

[0040] S4. The material obtained in step S3 is subjected to one or two calcinations to obtain rare earth manganese-zirconium composite compounds with grain boundaries and surface doping. The calcination conditions are 400-1000℃ for 1-20 hours; preferably, 500℃-900℃ for 3-10 hours. The obtained rare earth manganese-zirconium composite compound is calcined 1-2 times to obtain rare earth manganese-zirconium composite compound powder material with a specific structure. After the first calcination, it can be crushed and surface treated to avoid secondary sintering and agglomeration.

[0041] The particle size D50 of the post-processed rare earth manganese zirconium composite compound is less than 15 μm, preferably less than 10 μm. In this preparation method, rare earth, manganese, transition metals and other elements are added to the surface and grain boundaries of rare earth zirconium-based oxides through doping, resulting in rare earth manganese zirconium composite compounds containing perovskite, spinel, mullite and other structures. This increases the oxygen defect concentration at the surface and grain boundaries, increases the number of free active oxygen, improves its high-temperature catalytic activity, inhibits its high-temperature sintering, and at the same time reduces the amount of precious metals used in the catalyst.

[0042] According to a third aspect of the present invention, a rare-earth manganese-zirconium composite compound doped at grain boundaries and surfaces, as described in the first aspect of the invention, is provided for applications in motor vehicle exhaust purification, industrial waste gas treatment, and catalytic combustion. The rare-earth manganese-zirconium composite compound provided in the embodiments of the present invention significantly increases the amount of free active oxygen at the surface and grain boundaries through doping, which is beneficial to the catalytic oxidation of NO molecules. It has good effects in suppressing high-temperature sintering deactivation and reducing precious metal content, and can significantly improve the catalytic oxidation capacity of NO when applied in the fields of motor vehicle exhaust purification, industrial waste gas treatment, and catalytic combustion.

[0043] The present invention will be further illustrated below with specific examples, and the catalytic NO oxidation performance of the prepared rare earth manganese zirconium composite compound will be measured. The catalytic performance test conditions are consistent in all examples. The specific test steps are as follows: 50 mg of the prepared rare earth manganese zirconium composite compound is placed in a microreactor for catalyst activity evaluation. The concentrations of NO, NO2, and NO at the corresponding temperatures are recorded using an infrared gas analyzer (MKS). x The content of NO was used to calculate the conversion rate. Specific experimental conditions were as follows: Volumetric composition of the reaction gases: oxygen 10%, water 10%, carbon monoxide 300 ppm, nitric oxide 300 ppm, C3H6 300 ppm; balance gas was nitrogen; total flow rate was 150 mL / min, space velocity was 40000 h⁻¹. -1 Reaction temperature setting: Increase from room temperature to 400℃ at a rate of 20℃ / min, with a reaction time of 20min.

[0044] Comparative Example 1

[0045] According to Ce 0.05 Nd0.05 Mn 0.05 Zr 0.8 The molar ratio of Ce / Mn / Nd / Zr in the O2 rare earth zirconium-manganese composite oxide was 1:1:1:16 to obtain a mixed solution with a total cation concentration of 1.5M. Under stirring, the mixture was added uniformly to a 3.0M NaOH solution. The pH during precipitation was 10-14, the final pH was 10, and the temperature was controlled at 50℃. The precipitate was filtered, washed, dried, and calcined at 650℃ for 8 hours to obtain the bulk-doped rare earth manganese-zirconium composite compound Ce. 0.05 Nd 0.05 Mn 0.05 Zr 0.8 O2.

[0046] The rare earth manganese zirconium composite compound prepared by the method of Comparative Example 1 achieved a maximum conversion rate of 42% for the catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate was 357℃.

[0047] Comparative Example 2

[0048] According to Ce 0.1 Al 0.1 Mn 0.2 Zr 0.6 The Ce / Al / Mn / Zr molar ratio in the O2 rare earth zirconium-manganese composite oxide was 1:1:2:6 to obtain a 1.0M mixed solution. Under stirring, the mixed solution and 2.8M NaOH solution were added to the reactor at a uniform rate. The pH during precipitation was controlled at 9±0.2, the final pH was 9.2, and the temperature was controlled at 40℃. The precipitate was filtered, washed, dried, and calcined at 600℃ for 10 h to obtain the bulk-doped rare earth manganese-zirconium composite compound Ce. 0.1 Al 0.1 Mn 0.2 Zr 0.6 O2.

[0049] The rare earth manganese zirconium composite compound prepared by the method of Comparative Example 2 achieved a maximum conversion rate of 45% for the catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate was 352℃.

[0050] Example 1

[0051] According to Ce 0.05 Nd 0.05 Mn 0.05 Zr 0.8The Ce / Nd / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 0.5:1:16 to obtain a 1.5M mixed solution. Under stirring, the mixture was added uniformly to a 3.0M NaOH solution. The pH during precipitation was 10-14, the final pH was 10, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 7 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.8M Ce-containing Mn(NO3)2 solution, then heat-treated at 150℃ for 5 hours, and then calcined at 650℃ for 8 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.05 Nd 0.05 Mn 0.05 Zr 0.8 O2.

[0052] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 52% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 300℃.

[0053] Example 2

[0054] According to Ce 0.1 Al 0.1 Mn 0.2 Zr 0.6 The Ce / Al / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 0.5:1:6 to obtain a 1.0M mixed solution. Under stirring, the mixed solution and 2.8M NaOH solution were added to the reactor at a uniform rate. The pH during precipitation was controlled at 9±0.2, the final pH was 9.2, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 700℃ for 5 h to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.5M Ce-containing Mn(NO3)2 solution, then heat-treated at 170℃ for 10 h, and then calcined at 600℃ for 10 h to obtain a grain boundary and surface doped rare earth manganese zirconium composite compound Ce. 0.1 Al 0.1 Mn 0.2 Zr 0.6 O2.

[0055] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 55% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 308℃.

[0056] Example 3

[0057] According to Ce 0.05 Y 0.05 Mn 0.2 Zr 0.7The Ce / Y / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 0.5:0.2:7 to obtain a 1.2M mixed solution. Under stirring, a 2.6M urea solution was added to the mixture at a uniform rate. The pH during precipitation was 3-9, with a final pH of 9, and the temperature was controlled at 110℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 600℃ for 4 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.3M Y-containing MnCl2 solution, then heat-treated at 190℃ for 6 hours, followed by calcination at 800℃ for 7 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.05 Y 0.05 Mn 0.2 Zr 0.7 O2.

[0058] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 57% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 306℃.

[0059] Example 4

[0060] According to Ce 0.2 Nd 0.05 Si 0.05 Mn 0.2 Zr 0.5 The molar ratio of Ce / Nd / Si / Zr in the O2 rare earth zirconium manganese composite oxide was 1:0.5:0.5:5 to obtain a 1.5M mixed solution. Under stirring, the mixture was added uniformly to a 2.9M NaOH solution. The pH during precipitation was 8-14, with a final pH of 8, and the temperature was controlled at 60℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 7 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.1M Ce-containing Mn(CH3COO)2 solution, heat-treated at 200℃ for 5 hours, and then calcined at 820℃ for 9 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.2 Nd 0.05 Si 0.05 Mn 0.2 Zr 0.5 O2.

[0061] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 63% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 296℃.

[0062] Example 5

[0063] According to Ce 0.05 Nd 0.05 Y0.05 Al 0.1 Mn 0.2 Zr 0.7 The molar ratio of Ce / Nd / Y / Al / Zr in the O2 rare earth zirconium manganese composite oxide was 0.2:0.3:0.5:1:7 to obtain a 1.6M mixed solution. Under stirring, the mixed solution and 3.6M ammonia solution were added to the reactor at a uniform rate. The pH during precipitation was controlled at 10±0.2, the final pH was 10.2, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 700℃ for 5 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.3M Mn(NO3)2 solution containing Ce and Nd, then heat-treated at 200℃ for 5 hours, and then calcined at 600℃ for 5 hours to obtain a grain boundary and surface doped rare earth manganese zirconium composite compound Ce. 0.05 Nd 0.05 Y 0.05 Al 0.1 Mn 0.2 Zr 0.7 O2.

[0064] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 66% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 289℃.

[0065] Example 6

[0066] According to Ce 0.14 La 0.03 Nd 0.04 Y 0.05 Mn 0.16 Zr 0.58 The molar ratio of Ce / La / Nd / Y / Zr in the O2 rare earth zirconium manganese composite oxide was 5:2:3:5:58 to obtain a 1.5M mixed solution. Under stirring, the mixture was added uniformly to a 2.1M NaOH solution. The pH during precipitation was 8-11, with a final pH of 8, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 700℃ for 6 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.6M Mn(NO3)2 solution containing Ce, La, and Nd, and then heat-treated at 200℃ for 13 hours, followed by calcination at 750℃ for 10 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.14 La 0.03 Nd 0.04 Y 0.05 Mn 0.16 Zr 0.58 O2.

[0067] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 70% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 280℃.

[0068] Example 7

[0069] According to Ce 0.4 Nd 0.05 Hf 0.05 Mn 0.2 Zr 0.3 The molar ratio of Ce / Nd / Hf / Zr in the O2 rare earth zirconium manganese composite oxide was 3:0.5:0.5:3 to obtain a 1.5M mixed solution. Under stirring, 2.6M NaOH solution was added to the mixture at a uniform rate. The pH during precipitation was 5-10, with a final pH of 10, and the temperature was controlled at 60℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 7 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.9M Ce-containing Mn(CH3COO)2 solution and heat-treated at 210℃ for 7 hours, followed by calcination at 750℃ for 9 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.4 Nd 0.05 Hf 0.05 Mn 0.2 Zr 0.5 O2.

[0070] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention achieved a maximum conversion rate of 64% for the catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate was 292℃.

[0071] Example 8

[0072] According to Ce 0.4 La 0.02 Nd 0.05 Y 0.03 Mn 0.2 Zr 0.3 The molar ratio of Ce / La / Nd / Y / Zr in the O2 rare earth zirconium manganese composite oxide was 3:0.2:0.5:0.3:3 to obtain a 1.6M mixed solution. Under stirring, the mixture was added uniformly to a 2.8M ammonium bicarbonate solution. The pH during precipitation was 8±1, the final pH was 9.4, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 7 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.4M Ce-containing Mn(NO3)2 solution, then heat-treated at 200℃ for 9 hours, and then calcined at 750℃ for 10 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.4 La0.02 Nd 0.05 Y 0.03 Mn 0.2 Zr 0.3 O2.

[0073] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 62% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 299℃.

[0074] Example 9

[0075] According to Ce 0.2 Sm 0.2 La 0.02 Nd 0.05 Y 0.03 Mn 0.3 Zr 0.2 O 1.9 Rare earth zirconium-manganese composite oxides were prepared with a Ce / Sm / La / Nd / Y / Zr molar ratio of 1:1:0.2:0.5:0.3:2 to obtain a 1.4M mixed solution. Under stirring, the mixed solution and 2.6M NaOH solution were added uniformly to a reactor. The pH during precipitation was 8.5±0.5, the final pH was 9, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 700℃ for 5 hours to obtain rare earth zirconium-based oxides. These rare earth zirconium-based oxides were mixed with a 5.1M Mn(NO3)2 solution containing Ce and Sm, heat-treated at 300℃ for 7 hours, and then calcined at 600℃ for 9 hours to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound, Ce. 0.2 Sm 0.2 La 0.02 Nd 0.05 Y 0.03 Mn 0.3 Zr 0.2 O 1.9 .

[0076] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 59% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 310℃.

[0077] Example 10

[0078] According to Ce 0.1 Mn 0.15 Fe 0.05 Zr 0.7A Ce / Zr molar ratio of 0.5:7 was used to prepare a 1.5M mixed solution in rare earth zirconium-manganese composite oxide. Under stirring, the mixed solution was added uniformly to a reactor with a 1.2M ammonia solution. The pH during precipitation was 7±0.2, the final pH was 9, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 600℃ for 6 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 3.8M Ce-containing MnCl2 and FeCl3 solution, then heat-treated at 150℃ for 6 hours, followed by calcination at 500℃ for 10 hours to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound, Ce. 0.1 Mn 0.15 Fe 0.05 Zr 0.7 O2.

[0079] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 65% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 283℃.

[0080] Example 11

[0081] According to Ce 0.3 Mn 0.1 Fe 0.05 Co 0.05 Zr 0.5 A 1.2M mixed solution was prepared by mixing Ce / Zr in a 2:5 molar ratio of O2 rare earth zirconium manganese composite oxide. Under stirring, the mixture was added uniformly to a 2.1M NaOH solution. The pH during precipitation was 8-14, with a final pH of 9, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 7 hours to obtain rare earth zirconium-based oxide. This rare earth zirconium-based oxide was mixed with a 4.4M solution containing Ce (Mn(CH3COO)2, Co(CH3COO)2, and Fe(CH3COO)2), then heat-treated at 200℃ for 6 hours, followed by calcination at 750℃ for 8 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound, Ce. 0.3 Mn 0.1 Fe 0.05 Co 0.05 Zr 0.5 O2.

[0082] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 70% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 280℃.

[0083] Example 12

[0084] According to Ce 0.3 Mn0.1 Cu 0.05 Ti 0.05 Zr 0.5 A Ce / Zr molar ratio of 2:5 was used to prepare a 1.4M mixed solution in rare earth zirconium-manganese composite oxide. Under stirring, 1.8M NaOH solution was added to the mixture at a uniform rate. The pH during precipitation was 8-11, with a final pH of 10, and the temperature was controlled at 55℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 600℃ for 6 hours to obtain rare earth zirconium-based oxide. This rare earth zirconium-based oxide was mixed with a 5.2M solution containing Ce (Mn(NO3)2), Cu(NO3)2, and Ti(NO3)4, then heat-treated at 150℃ for 8 hours, followed by calcination at 800℃ for 5 hours to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound (Ce). 0.3 Mn 0.1 Cu 0.05 Ti 0.05 Zr 0.5 O2.

[0085] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 68% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 281℃.

[0086] Example 13

[0087] According to Ce 0.2 La 0.05 Pr 0.05 Mn 0.1 Fe 0.1 Zr 0.5 The Ce / La / Pr / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 1:0.3:0.5:5 to obtain a 1.4M mixed solution. Under stirring, the mixed solution and 2.8M NaOH solution were added to the reactor at a uniform rate. The pH during precipitation was controlled at 9±0.2, the final pH was 10.7, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 5 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.5M solution containing Ce and La in Mn(NO3)2 and Fe(NO3)3, then heat-treated at 200℃ for 10 hours, and then calcined at 600℃ for 9 hours to obtain a grain boundary and surface doped rare earth manganese zirconium composite compound Ce. 0.2 La 0.05 Pr 0.05 Mn 0.1 Fe 0.1 Zr 0.5 O2.

[0088] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 70% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 278℃.

[0089] Example 14

[0090] According to Ce 0.4 Nd 0.05 Mn 0.2 Fe 0.1 Sn 0.05 Zr 0.2 The Ce / Nd / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 1:0.5:2 to obtain a 1.6M mixed solution. Under stirring, the mixture was added uniformly to a 3.4M ammonium bicarbonate solution. The pH during precipitation was 9-10, with a final pH of 9, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 600℃ for 4 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 3.8M Ce-containing MnCl2, FeCl3, and SnCl4 solution, then heat-treated at 250℃ for 5 hours, followed by calcination at 800℃ for 7 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.4 Nd 0.05 Mn 0.2 Fe 0.1 Sn 0.05 Zr 0.2 O2.

[0091] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 72% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 268℃.

[0092] Example 15

[0093] According to Ce 0.2 Sm 0.2 La 0.02 Nd 0.05 Y 0.03 Mn 0.1 Co 0.1 Zr 0.3The molar ratio of Ce / Sm / La / Nd / Y / Zr in the O2 rare earth zirconium manganese composite oxide was 1:1:0.2:0.5:0.3:3 to obtain a 1.4M mixed solution. Under stirring, the mixed solution and 2.7M NaOH solution were added to the reactor at a uniform rate. The pH during precipitation was controlled at 8±0.2, the final pH was 9.4, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 4 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.6M solution containing Ce and Sm of Mn(NO3)2 and Co(NO3)2, then heat-treated at 100℃ for 11 hours, and then calcined at 600℃ for 9 hours to obtain a grain boundary and surface doped rare earth manganese zirconium composite compound Ce. 0.2 Sm 0.2 La 0.02 Nd 0.05 Y 0.03 Mn 0.3 Zr 0.2 O 1.9 .

[0094] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 74% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 264℃.

[0095] Example 16

[0096] According to Ce 0.2 Si 0.1 Mn 0.15 W 0.05 Zr 0.5 The Ce / Si / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 1:1:5 to obtain a 1.2M mixed solution. Under stirring, the mixture was added uniformly to a 2.2M NaOH solution. The pH during precipitation was 9-14, with a final pH of 9, and the temperature was controlled at 30℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 750℃ for 5 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.4M Ce-containing Mn(CH3COO)2 and hexacarbonyl tungsten solution, then heat-treated at 150℃ for 7 hours, followed by calcination at 800℃ for 7 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.2 Si 0.1 Mn 0.15 W 0.05 Zr 0.5 O2.

[0097] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 76% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 246℃.

[0098] Example 17

[0099] According to Ce 0.1 Nd 0.05 Y 0.05 Mn 0.15 Cu 0.15 Zr 0.5 The Ce / Nd / Y / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 1:1:1:10 to obtain a 1.4M mixed solution. Under stirring, the mixture was added uniformly to a 1.9M urea solution. The pH during precipitation was 8-10, with a final pH of 8, and the temperature was controlled at 100℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 850℃ for 4 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.2M solution containing Ce (Mn(NO3)2) and Cu(NO3)2, then heat-treated at 200℃ for 7 hours, followed by calcination at 750℃ for 6 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound, Ce. 0.2 Nd 0.05 Hf 0.05 Mn 0.1 Nb 0.1 Zr 0.5 O2.

[0100] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 78% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 240℃.

[0101] Example 18

[0102] According to Ce 0.2 Al 0.1 Mn 0.05 Cr 0.1 Zr 0.55The Ce / Al / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 1:1:5.5 to obtain a 1.5M mixed solution. Under stirring, the mixed solution and 3.2M NaOH solution were added to the reactor at a uniform rate. The pH during precipitation was controlled at 9±0.2, the final pH was 9.5, and the temperature was controlled at 45℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 700℃ for 6 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.6M Ce-containing Mn(NO3)2 and Cr(NO3)3 solution and then heat-treated at 200℃ for 6 hours, followed by calcination at 900℃ for 3 hours to obtain a grain boundary and surface doped rare earth manganese zirconium composite compound Ce. 0.2 Al 0.1 Mn 0.05 Cr 0.1 Zr 0.55 O2.

[0103] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 74% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 249℃.

[0104] Example 19

[0105] According to Ce 0.1 Al 0.1 Mn 0.1 Zn 0.1 Zr 0.6 The Ce / Al / Zr molar ratio in the O2 rare earth zirconium manganese composite oxide was 0.5:1:6 to obtain a 1.4M mixed solution. Under stirring, 2.6M NaOH solution was added to the mixture at a uniform rate. The pH during precipitation was 5-9, with a final pH of 9, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 650℃ for 8 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.7M Ce-containing MnCl2 and ZnCl2 solution, then heat-treated at 150℃ for 8 hours, and then calcined at 800℃ for 8 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.1 Al 0.1 Mn 0.1 Zn 0.1 Zr 0.6 O2.

[0106] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 72% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 267℃.

[0107] Example 20

[0108] According to Ce0.15 La 0.05 Y 0.05 Al 0.05 Mn 0.2 Zr 0.5 O 1.98 P 0.01 Rare earth zirconium-manganese composite oxides were prepared with a Ce / La / Y / Al / Zr molar ratio of 2:1:1:1:10 to obtain a 1.0 M mixed solution. Under stirring, the mixture was added uniformly to a 3.2 M ammonia solution. The pH during precipitation was 8-10, with a final pH of 8, and the temperature was controlled at 40 °C. The precipitate was filtered, washed, and dried. The dried product was calcined at 800 °C for 5 h to obtain rare earth zirconium-based oxides. These rare earth zirconium-based oxides were mixed with a 4.7 M Ce-containing MnCl2 and H3PO4 solution, then heat-treated at 200 °C for 7 h, followed by calcination at 750 °C for 7 h to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound, Ce. 0.15 La 0.05 Y 0.05 Al 0.05 Mn 0.2 Zr 0.5 O 1.98 P 0.01 .

[0109] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 67% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 279℃.

[0110] Example 21

[0111] According to Ce 0.15 Mn 0.2 Ni 0.15 Zr 0.5 O 1.98 S 0.02 Rare earth zirconium manganese composite oxides were prepared with a Ce / Zr molar ratio of 0.2:1 to obtain a 1.2M mixed solution. Under stirring, the mixed solution and 2.6M NaOH solution were added uniformly to a reactor. The pH during precipitation was 9±0.2, the final pH was 10.4, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 6 hours to obtain rare earth zirconium-based oxides. These rare earth zirconium-based oxides were mixed with a 3.9M solution containing Ce (MnCl2, NiCl2, and dilute sulfuric acid), then heat-treated at 200℃ for 6 hours, followed by calcination at 600℃ for 10 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound (Ce). 0.15 Mn 0.2 Ni 0.15 Zr 0.5 O1.98 S 0.02 .

[0112] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 72% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 268℃.

[0113] Example 22

[0114] According to Ce 0.2 Mn 0.2 Cu 0.1 Zr 0.5 O 1.98 N 0.01 Rare earth zirconium manganese composite oxides were prepared with a Ce / Zr molar ratio of 1:5 to obtain a Ce concentration of 0.5M. 3+ and Zr 4+ A mixed solution was prepared by uniformly adding the mixture to a 3.1M ammonia solution under stirring. The pH during precipitation was 9-11, with a final pH of 9, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was then calcined at 600℃ for 9 hours to obtain rare earth zirconium-based oxides. These rare earth zirconium-based oxides were mixed with a 4.2M solution containing Ce, MnSO4, CuSO4, and pyridine nitrogen. The mixture was then heat-treated at 150℃ for 8 hours and calcined at 900℃ for 9 hours to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound, Ce. 0.2 Mn 0.2 Cu 0.1 Zr 0.5 O 1.98 N 0.01 .

[0115] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 64% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 295℃.

[0116] Example 23

[0117] According to Ce 0.14 La 0.03 Nd 0.04 Y 0.05 Mn 0.16 Zr 0.58 O 1.98 F 0.04Rare earth zirconium-manganese composite oxides were prepared with a Ce / La / Nd / Y / Zr molar ratio of 6:2:4:3:58 to obtain a 1.5M mixed solution. Under stirring, the mixture was added uniformly to a 2.7M NaOH solution. The pH during precipitation was 8-13, with a final pH of 8, and the temperature was controlled at 80℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 650℃ for 7 hours to obtain rare earth zirconium-based oxides. These rare earth zirconium-based oxides were mixed with a 4.8M Mn(NO3)2 solution containing Ce, La, and Y, and an NH4F solution, and then heat-treated at 200℃ for 6 hours, followed by calcination at 800℃ for 11 hours to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound, Ce. 0.14 La 0.03 Nd 0.04 Y 0.05 Mn 0.1 6Zr 0.58 O 1.98 F 0.04 .

[0118] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 68% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 283℃.

[0119] Example 24

[0120] According to Ce 0.15 La 0.04 Nd 0.04 Y 0.06 Mn 0.16 Zr 0.55 The molar ratio of Ce / La / Nd / Y / Zr in the O2 rare earth zirconium manganese composite oxide was 10:3:4:6:55. The mixture was prepared by dissolving it in water to obtain a 1.5M mixed solution. Under stirring, the mixture was added uniformly to a 2.1M ammonia solution. The pH during precipitation was 8-10, with a final pH of 10.1, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 6 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.8M MnCl2 solution containing Ce and La and then heat-treated at 200℃ for 6 hours. The heat-treated product was washed, dried, heat-treated at 250℃ for 5 hours, and then calcined at 800℃ for 6 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.15 La 0.04 Nd 0.04 Y 0.06 Mn 0.16 Zr 0.55 O2.

[0121] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 71% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 279℃.

[0122] Example 25

[0123] According to Ce 0.15 Nd 0.05 Mn 0.05 V 0.05 Sn 0.05 Zr 0.65 The Ce / Nd / Zr molar ratio in the O2 rare earth zirconium-manganese composite oxide was 2:1:13, and it was dissolved in water to obtain a 1.5M mixed solution. Under stirring, a 2.5M ammonia solution was added to the mixture at a uniform rate. The pH during precipitation was 5-11, with a final pH of 11, and the temperature was controlled at 50℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 700℃ for 6 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.8M solution containing Ce (Mn(CH3COO)2, Sn(CH3COO)4, and VCl3), and then heat-treated at 180℃ for 15 hours, followed by calcination at 500℃ for 4 hours. The calcined product was pulverized and calcined at 800℃ for 4 hours to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound Ce. 0.15 Nd 0.05 Mn 0.05 V 0.05 Sn 0.05 Zr 0.65 O2.

[0124] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 65% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 290℃.

[0125] Example 26

[0126] According to Ce 0.15 Nd 0.05 Pr 0.05 Eu 0.05 Mn 0.2 Zr 0.5 O 1.98 S 0.02A mixture of Ce / Nd / Pr / Eu / Zr in a rare earth zirconium-manganese composite oxide with a molar ratio of 2:1:1:1:10 was prepared to obtain a 1.5M mixed solution. Under stirring, the mixed solution was added uniformly to a reactor along with a 2.2M ammonium bicarbonate solution. The pH during precipitation was controlled at 8±0.2, with a final pH of 10, and the temperature was controlled at 44℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 600℃ for 8 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.5M Ce-containing manganese sulfate solution and heat-treated at 280℃ for 7 hours, followed by calcination at 650℃ for 3 hours. The calcined product was then pulverized and calcined at 700℃ for 10 hours to obtain a grain boundary and surface-doped rare earth manganese-zirconium composite compound with Ce. 0.15 Nd 0.05 Pr 0.05 Eu 0.05 Mn 0.2 Zr 0.5 O 1.98 S 0.02 .

[0127] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention achieved a maximum conversion rate of 64% for the catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate was 291℃.

[0128] Example 27

[0129] According to Ce 0.4 Sc 0.02 Yb 0.05 Y 0.03 Mn 0.1 Ti 0.1 Zr 0.3 O 1.98 S 0.02 Rare earth zirconium manganese composite oxides were prepared with a Ce / Sc / Yb / Y / Zr molar ratio of 25:2:5:3:30 to obtain a 1.5M mixed solution. Under stirring, the mixed solution was added uniformly to a reactor with a 2.2M ammonia solution. The pH during precipitation was controlled at 9.5±0.2, with a final pH of 10, and the temperature was controlled at 40℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 550℃ for 10 hours to obtain rare earth zirconium-based oxides. These rare earth zirconium-based oxides were mixed with a 4.4M Ce-containing manganese sulfate and titanium oxysulfate solution, heat-treated at 180℃ for 8 hours, and then calcined at 450℃ for 10 hours. The calcined product was pulverized and calcined at 650℃ for 10 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound, Ce. 0.4 Sc 0.02 Yb 0.05 Y 0.03 Mn 0.1 Ti0.1 Zr 0.3 O 1.98 S 0.02 .

[0130] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 67% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 280℃.

[0131] Example 28

[0132] According to Ce 0.2 Nd 0.05 Tm 0.05 Mn 0.1 Zn 0.1 Zr 0.5 The molar ratio of Ce / Nd / Tm / Zr in the O2 rare earth zirconium manganese composite oxide was 3:1:1:10. The mixture was dissolved in water to obtain a 1.5M solution. Under stirring, the solution was added uniformly to 2.1M ammonia water. The pH during precipitation was 8-11, with a final pH of 10.5, and the temperature was controlled at 55℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 2 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.6M solution of Ce-containing Mn(NO3)2 and Zn(NO3)2, and then heat-treated at 280℃ for 6 hours, followed by calcination at 850℃ for 11 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound, Ce. 0.2 Nd 0.05 Tm 0.05 Mn 0.1 Zn 0.1 Zr 0.5 O2.

[0133] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 63% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 290℃.

[0134] Example 29

[0135] According to Ce 0.14 La 0.03 Gd 0.04 Ho 0.05 Mn 0.15 Cr 0.5 Zr 0.58The molar ratio of Ce / La / Gd / Ho / Zr in the O2 rare earth zirconium manganese composite oxide was 10:2:4:5:58. The mixture was dissolved in water to obtain a 1.5M mixed solution. Under stirring, the mixture was added uniformly to a 2.1M ammonium bicarbonate solution. The pH during precipitation was 9-11, with a final pH of 9, and the temperature was controlled at 60℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 800℃ for 4 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.7M Mn(NO3)2 solution containing Ce and La, and then heat-treated at 150℃ for 10 hours, followed by calcination at 680℃ for 12 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound, Ce. 0.14 La 0.03 Gd 0.04 Ho 0.05 Mn 0.15 Cr 0.5 Zr 0.58 O2.

[0136] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 63% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 291℃.

[0137] Example 30

[0138] According to Ce 0.14 Eu 0.03 Al 0.04 Si 0.05 Mn 0.16 Zr 0.58 The molar ratio of Ce / Eu / Al / Si / Zr in the O2 rare earth zirconium manganese composite oxide was 12:2:4:5:58 to obtain a 1.5M mixed solution. Under stirring, the mixture was added uniformly to a 2.1M NaOH solution. The pH during precipitation was 8-11, with a final pH of 8, and the temperature was controlled at 90℃. The precipitate was filtered, washed, and dried. The dried product was calcined at 760℃ for 8 hours to obtain rare earth zirconium-based oxide. The rare earth zirconium-based oxide was mixed with a 4.2M Mn(NO3)2 solution containing Ce and Eu, then heat-treated at 200℃ for 7 hours, followed by calcination at 500℃ for 13 hours to obtain a grain boundary and surface-doped rare earth manganese zirconium composite compound Ce. 0.14 Eu 0.03 Al 0.04 Si 0.05 Mn 0.16 Zr 0.58 O2.

[0139] The rare earth manganese zirconium composite compound prepared by the method of this embodiment of the invention has a maximum conversion rate of 60% for catalytic oxidation of NO, and the conversion temperature corresponding to the maximum conversion rate is 292℃.

[0140] As can be seen from the data of the above comparative examples and embodiments, compared with the preparation methods provided in the comparative examples, the NO conversion rate of the product obtained is less than 50%, and the conversion temperature is 350℃. The rare earth manganese zirconium composite compound obtained by the preparation methods of the various embodiments of the present invention has a maximum NO conversion rate of 78%, and the conversion temperature corresponding to the maximum conversion rate is 240℃. The NO conversion rate is significantly improved, and the corresponding conversion temperature is significantly reduced, achieving significant and beneficial technical effects.

[0141] In summary, this invention relates to a grain boundary and surface-doped rare-earth manganese-zirconium composite compound, its preparation method, and its applications. A rare-earth manganese oxide with a special structure is formed at the grain boundaries and surface of rare-earth zirconium-based oxides through grain boundary doping, resulting in a rare-earth manganese-zirconium composite compound. This increases oxygen defects at the grain boundaries and surface, thereby increasing the amount of active oxygen and enhancing the catalytic activity of the rare-earth manganese-zirconium composite compound, inhibiting high-temperature sintering, and improving its ability to catalyze NO oxidation. Applying this rare-earth manganese-zirconium composite compound to catalysts can significantly reduce the amount of precious metals required.

[0142] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A rare-earth manganese-zirconium composite compound doped at grain boundaries and surfaces, characterized in that, The chemical formula of the rare earth manganese zirconium composite compound is RE a Mn b Zr c L d M e O (2-δ) D β RE represents rare earth elements; M and L are cation dopants, and D is anion dopant; the grain boundaries and surface of the rare earth manganese-zirconium composite compound contain dopants M and D; the cation dopant L includes one or more combinations of Al, Si, Hf, Ba, Sr, Mg, and Ca; the dopant D includes one or more combinations of anions N, P, F, and S; the dopants M and D at the grain boundaries and surface of the rare earth manganese-zirconium composite oxide are in the form of one or more oxides, nitrogen-containing compounds, fluorides, phosphates, and sulfates. Where, 0.1≤a≤0.5, 0.05≤b≤0.4, 0.2≤c≤0.8, 0<d≤0.2, 0<e≤0.2, 0≤δ≤0.1, 0<β≤0.1, a+b+c+d+e=1.

2. The rare-earth manganese-zirconium composite compound with grain boundaries and surface doping according to claim 1, characterized in that, The RE includes one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc.

3. The rare-earth manganese-zirconium composite compound with grain boundaries and surface doping according to claim 1, characterized in that, The cation doping element M includes one or more of Fe, Co, Ni, Cu, Zn, V, Ti, Cr, Mo, W, Sn, and Nb.

4. The rare-earth manganese-zirconium composite compound with grain boundaries and surface doping according to claim 1, characterized in that, The total amount of +3 and +4 valence states of Mn at the surface and grain boundaries of the rare earth manganese zirconium composite compound accounts for more than 80% of all Mn valence states.

5. The rare-earth manganese-zirconium composite compound with grain boundaries and surface doping according to claim 2, characterized in that, The RE is one or more of La, Ce, Pr, Nd, Sm, Eu, Gd and Y.

6. The rare-earth manganese-zirconium composite compound with grain boundaries and surface doping according to claim 4, characterized in that, The total amount of +3 and +4 valence states of Mn at the surface and grain boundaries of the rare earth manganese zirconium composite compound accounts for more than 90% of all Mn valence states.

7. A method for preparing a rare-earth manganese-zirconium composite compound with grain boundaries and surfaces as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Mix the required stoichiometric ratio of a mixed salt aqueous solution of Zr and RE or a mixed salt aqueous solution of Zr, RE and L with an alkaline solution to carry out a precipitation reaction. After filtration, washing, drying and calcination, a rare earth zirconium-based oxide containing RE and L is obtained. S2. Mix the mixed salt aqueous solution of Mn and RE in the required stoichiometric ratio or the mixed salt aqueous solution of Mn, RE and M with the rare earth zirconium-based oxide obtained in step S1 to obtain a wet composite compound. S3. Perform one or two heat treatments on the wet composite compound material obtained in step S2. S4. The material obtained in step S3 is subjected to one or two calcination treatments to obtain rare earth manganese zirconium composite compounds doped with grain boundaries and surfaces. The dopant element D is added in step S2, or in both steps S1 and S2.

8. The method according to claim 7, characterized in that, Dopant element D is added in combination with one or more of nitrates, fluorides, phosphates and sulfates.

9. The method according to claim 7, characterized in that, The manganese source in the mixed salt solution of steps S1 and S2 includes one or more combinations of chlorides, nitrates, sulfates and acetates; the zirconium source includes one or more combinations of chlorine oxides, nitrates, sulfates, acetates and citrates; the salt solution of M, L and RE includes one or more combinations of liquid salts of chlorides, nitrates, sulfates, acetates, citrates and amino acid salts and organosilicon compounds.

10. The method according to claim 7, characterized in that, The alkaline solution includes magnesium bicarbonate, urea, and at least one of the hydroxides, carbonates, or bicarbonates of at least one of the elements selected from ammonium, sodium, and potassium.

11. The method according to claim 7, characterized in that, During the precipitation process in step S1, the pH value is controlled between 4.5 and 14; the pH value at the precipitation endpoint is controlled between 8 and 13; and the temperature during the precipitation process is between 0 and 120°C.

12. The method according to claim 7, characterized in that, The rare earth zirconium-based oxide is calcined at 500-1000℃ for 1-20 hours.

13. The method according to claim 7, characterized in that, The heat treatment temperature is 100-500℃, and the time is 2-30h.

14. The method according to claim 7, characterized in that, The calcination conditions are maintained at 400-1000℃ for 1-20 hours.

15. The method according to claim 7, characterized in that, The particle size D50 of the post-processed rare earth manganese zirconium composite compound is less than 15 μm.

16. The method according to claim 7, characterized in that, After calcination, rare earth zirconium-based oxides form rare earth manganese oxides with perovskite, spinel, or mullite structures on their surface and at grain boundaries.

17. The method according to claim 8, characterized in that, Dopant element D is added in combination with one or more of nitrates and sulfates.

18. The method according to claim 9, characterized in that, The manganese source in the mixed salt solution of steps S1 and S2 is manganese nitrate; the zirconium source is zirconium oxynitrate; and the salt solutions of M, L and RE are nitrates.

19. The method according to claim 10, characterized in that, The alkaline solution is at least one of sodium hydroxide, urea, ammonia, and ammonium bicarbonate.

20. The method according to claim 11, characterized in that, The pH value during the precipitation process in step S1 is 5-11; the pH value at the precipitation endpoint is 9-11; and the temperature during the precipitation process is 20-80℃.

21. The method according to claim 12, characterized in that, The rare earth zirconium-based oxide is calcined at 600℃-900℃ for 2-10 hours.

22. The method according to claim 13, characterized in that, The heat treatment temperature is 150-300℃, and the time is 6-12h.

23. The method according to claim 14, characterized in that, The calcination conditions are maintained at 500℃-900℃ for 3-10 hours.

24. The method according to claim 15, characterized in that, The particle size D50 of the post-processed rare earth manganese zirconium composite compound is less than 10 μm.

25. The application of the grain boundary and surface doped rare earth manganese zirconium composite compound as described in any one of claims 1-6 in the fields of motor vehicle exhaust purification, industrial waste gas treatment and catalytic combustion.

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