A grain boundary and surface doped cerium-zirconium composite oxide, its preparation method and application

Abstract

This invention relates to a grain boundary and surface-doped cerium-zirconium composite oxide, its preparation method, and its applications. The doping elements in the cerium-zirconium composite oxide are partially or entirely located at its grain boundaries and surface, increasing the number of defects and vacancies, enhancing oxygen migration capacity, and exhibiting good high-temperature stability. This cerium-zirconium composite oxide can inhibit the migration, aggregation, and growth of noble metal particles, enhance the high-temperature stability of noble metal catalysts, and reduce the amount of noble metal required. It can be applied in fields such as vehicle exhaust purification, natural gas catalytic combustion, organic waste gas purification, and industrial flue gas denitrification.

Description

Technical Field

[0001] This invention relates to the field of cerium-zirconium composite oxide technology, and more particularly to a grain boundary and surface doped cerium-zirconium composite oxide, its preparation method, and its application. Background Technology

[0002] With increasingly stringent emission standards for vehicle exhaust, industrial waste gas, and flue gas both domestically and internationally, the performance requirements for catalysts used in vehicle exhaust purification and industrial waste gas and flue gas treatment are also rising. As mobile pollution sources, vehicle exhaust gases undergo continuous changes in composition and properties during operation, making it difficult for ordinary catalysts to effectively purify them. Therefore, catalysts containing platinum, palladium, and rhodium for automotive and motorcycle exhaust purification have been developed. These catalysts utilize a key active coating material: cerium-zirconium composite oxide. The cerium oxide in the cerium-zirconium composite oxide exhibits variable valence states, undergoing a Ce2 oxidation state in oxidizing or reducing atmospheres. 4+ and Ce 3+ The reversible changes in the process enable cerium-zirconium composite oxides to store and release oxygen, effectively widening the air-fuel ratio window of the catalyst and significantly improving the catalytic performance of automotive exhaust purification catalysts. Because cerium-zirconium composite oxides improve the dispersion and utilization of precious metals supported on the catalyst, the amount of precious metals used in the catalyst can be significantly reduced. Cerium-zirconium composite oxides are an essential key material for automotive exhaust purification catalysts. Since automotive exhaust purification catalysts operate in harsh environments, with high temperatures (sometimes exceeding 900℃) and the presence of water vapor, the catalysts need high temperature resistance. This requires cerium-zirconium composite oxides to have not only a high specific surface area but also good high-temperature stability. Furthermore, cerium-zirconium composite oxides also have broad application prospects in natural gas catalytic combustion, industrial organic waste gas treatment, and industrial flue gas denitrification catalysts.

[0003] Under the high temperatures of automotive exhaust, the structure of cerium-zirconium composite oxides undergoes changes, resulting in a continuous decrease in specific surface area and a deterioration in performance. In particular, the high-temperature stability of cerium-zirconium composite oxides needs improvement to meet increasingly stringent automotive emission standards. Furthermore, in the application of cerium-zirconium composite oxides as catalysts for automotive exhaust purification, the platinum, palladium, and rhodium noble metal particles supported on the oxides are prone to migration, aggregation, and growth under prolonged exposure to high-temperature exhaust gases, leading to catalyst deactivation. Summary of the Invention

[0004] Based on the above-mentioned situation of the prior art, the purpose of the present invention is to provide a grain boundary and surface doped cerium-zirconium composite oxide, its preparation method and application, which improves the high-temperature stability of cerium-zirconium composite oxide, increases oxygen vacancies and defects, etc., and the catalyst prepared by using it is conducive to the efficient loading of noble metal particles, inhibits the migration, aggregation and growth of noble metal particles, thereby improving the high-temperature stability of the catalyst.

[0005] To achieve the above objectives, a first aspect of the present invention provides a cerium-zirconium composite oxide doped at grain boundaries and surfaces, the cerium-zirconium composite oxide having the chemical formula Ce x Zr 1-x-y M y O 2-α D δ ;in,

[0006] M represents a cation-doped element, and D represents an anion-doped element;

[0007] 0.1≤x≤0.9, 0 <y≤0.2,0≤α≤0.1,0≤δ≤0.1。

[0008] Furthermore, the grain boundaries and surface of the cerium-zirconium composite oxide contain oxides of doped element M, or one or more of the following: oxides of doped element M and nitrogen-containing compounds, fluorides, phosphates, and sulfates formed by M and D.

[0009] Furthermore, the doping element M is one or more of rare earth elements other than cerium, transition metal elements, alkaline earth metal elements, and Al and Si; the doping element D is one or more of N, S, F, and P.

[0010] Furthermore, the rare earth element is one or more of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc; the transition metal element is one or more of Cu, Mn, Ni, Fe, Zn, Co, Ti, Hf, Cr, and W; and the alkaline earth metal element is one or more of Mg, Ca, Sr, and Ba.

[0011] Furthermore, the cation doping element M is one or more of La, Pr, Nd, Sm, Eu, Yb, Y, Sc, Cu, Mn, Hf, Fe, Co, Al, Si, Mg, Ba and Sr.

[0012] Furthermore, the specific surface area of ​​the cerium-zirconium composite oxide after being held at 1000℃ for 10 hours is greater than 50 m². 2 / g, preferably greater than 60m 2 / g; Specific surface area greater than 35m² after heat treatment at 1100℃ for 4 hours. 2 / g, preferably greater than 40m 2 / g.

[0013] Furthermore, the total pore volume of the cerium-zirconium composite oxide is greater than 0.4 mL / g, and the total pore volume after being kept at 1000℃ for 10 h is greater than 0.2 mL / g.

[0014] A second aspect of the present invention provides a method for preparing grain boundary and surface-doped cerium-zirconium composite oxides as described in the first aspect of the present invention, comprising the steps of:

[0015] S1. Prepare aqueous solutions containing cerium ions and zirconium ions in the required stoichiometric ratio for the product, and mix them to obtain a mixed solution; carry out a precipitation reaction with an alkaline substance in a reactor, and filter, wash, dry and calcine the obtained precipitate to obtain cerium-zirconium oxide.

[0016] S2. The cerium-zirconium oxide obtained in step S1 is mixed with the liquid salt of doped element M, dried, and then subjected to one or two heat treatments, followed by one or two calcinations to obtain cerium-zirconium composite oxides with grain boundaries and surfaces doped.

[0017] Furthermore, the aqueous solution containing zirconium ions in step S1 includes one or more aqueous solutions of zirconium oxychloride, zirconium oxynitrate, zirconium sulfate, zirconium acetate, and zirconium citrate.

[0018] Furthermore, the aqueous solution containing cerium ions in step S1 includes one or more aqueous solutions of cerium chloride, cerium nitrate, cerium sulfate, cerium acetate, and cerium citrate.

[0019] Furthermore, the alkaline substance includes magnesium bicarbonate, urea, and at least one of the hydroxides, carbonates, or 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 reaction temperature during the precipitation process is 0–120℃, preferably 20–80℃.

[0021] Furthermore, the liquid salt of the dopant element M includes one or more of the following: molten salts or aqueous solutions of chlorides, nitrates, sulfates, acetates, citrates, amino acid salts, and organosilicon compounds.

[0022] Furthermore, the dopant element M is added in one or both of the steps S1 and S2.

[0023] Furthermore, the dopant element D is added in one or both of steps S1 and S2. Furthermore, the dopant element D is added through one or more combinations of nitrates, fluorides, phosphates, and sulfates.

[0024] Furthermore, the calcination temperature in step S1 is 500–1050°C, and the time is 1–24 h; preferably, the calcination temperature is 600–950°C, and the time is 3–12 h.

[0025] Furthermore, the heat treatment temperature in step S2 is 100–600°C, and the time is 0.5–24 h; preferably, the heat treatment temperature is 150–450°C, and the time is 1–12 h.

[0026] Furthermore, the calcination temperature in step S2 is 500–1050°C, and the time is 1–24 h; preferably, the calcination temperature is 600–950°C, and the time is 3–12 h.

[0027] A third aspect of the present invention provides a catalyst prepared from a cerium-zirconium composite oxide with grain boundaries and surface doping as described in the first aspect of the present invention.

[0028] A fourth aspect of the present invention provides the application of the catalyst as described in the third aspect of the present invention in the fields of motor vehicle exhaust purification, natural gas catalytic combustion, organic waste gas purification, and industrial flue gas denitrification treatment.

[0029] In summary, this invention provides a grain boundary and surface-doped cerium-zirconium composite oxide, its preparation method, and its applications, to improve the high-temperature stability and catalytic performance of cerium-zirconium composite oxides. The cerium-zirconium composite oxide provided by this invention contains oxides of dopant element M, or oxides of dopant element M and nitrogen-containing compounds, fluorides, phosphates, and sulfates formed by M and D at the grain boundaries and surface of the cerium-zirconium composite oxide; dopant element M, or M and D, are located at the grain boundaries and surface of the cerium-zirconium composite oxide. The interaction between the dopant element and the grains in this cerium-zirconium composite oxide is enhanced, and the dopants at the grain boundaries disperse and coat the cerium-zirconium grains, resulting in good high-temperature stability of the cerium-zirconium composite oxide. Simultaneously, the increased number of defects and vacancies in the cerium-zirconium composite oxide enhances oxygen migration ability, effectively improving the catalytic activity of the catalyst and reducing the amount of precious metals required. Furthermore, this cerium-zirconium composite oxide can inhibit the migration, aggregation, and growth of precious metal particles, enhancing the high-temperature stability of precious metal catalysts, and can be applied in fields such as motor vehicle exhaust purification, natural gas catalytic combustion, organic waste gas purification, and industrial flue gas denitrification treatment.

[0030] The present invention has the following beneficial technical effects compared with the prior art:

[0031] (1) The cerium-zirconium composite oxide with grain boundaries and surface doping provided in the embodiments of the present invention contains oxides of dopant element M at the grain boundaries and surface, or oxides of dopant element M and nitrogen-containing compounds, fluorides, phosphates and sulfates formed by M and D, etc.; dopant element M, or M and D, are located at the grain boundaries and surface of the cerium-zirconium composite oxide. Because this cerium-zirconium composite oxide has abundant defects and vacancies, especially the defects located at the grain boundaries are more abundant, the interaction between the dopant element and the grains is enhanced, and the dopants at the grain boundaries play a role in dispersing and coating the cerium-zirconium grains, thereby improving the high-temperature stability of the cerium-zirconium composite oxide.

[0032] (2) The cerium-zirconium composite oxide with grain boundary and surface doping provided in the embodiments of the present invention, through doping at grain boundary and surface, especially at grain boundary, makes the cerium-zirconium composite oxide have abundant grain defects, thereby improving the activity of the dopant and the effective utilization rate of the dopant, and promoting the catalytic effect of the dopant.

[0033] (3) The catalyst prepared by loading noble metals such as platinum, palladium, and rhodium onto the cerium-zirconium composite oxide with grain boundaries and surface doping of the present invention has more defects and dopants with high activity and abundant defect sites. Compared with conventional cerium-zirconium composite oxides, it is more conducive to the efficient dispersion and loading of noble metal catalytic particles such as platinum, palladium, and rhodium, and has more defect sites. Therefore, it effectively improves the catalytic activity of the catalyst and reduces the amount of noble metals used in the catalyst. In addition, the noble metal particles preferentially combine with the dopants at the grain boundaries, and there is a strong interaction between the two, thereby inhibiting the migration, aggregation, and growth of noble metal catalytic particles at high temperatures, thereby improving the high-temperature stability of the catalyst. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the preparation process of the cerium-zirconium composite oxide with grain boundaries and surface doping according to the present invention. Detailed Implementation

[0035] 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.

[0036] In a first aspect, the present invention provides a grain boundary and surface-doped cerium-zirconium composite oxide, the cerium-zirconium composite oxide having the chemical formula Ce x Zr 1-x-y M y O 2-α D δ; M is a cation doping element, and D is an anion doping element; 0.1 ≤ x ≤ 0.9, 0 < y ≤ 0.2, 0 ≤ α ≤ 0.1, 0 ≤ δ ≤ 0.1; preferably, 0.01 ≤ δ ≤ 0.08.

[0037] The grain boundaries and surfaces of the cerium-zirconium composite oxide contain an oxide of doping element M, or one or more of a nitrogen-containing compound, fluoride, phosphate, and sulfate formed by doping element M and M and D. The doping element M, or M and D, is located at the grain boundaries and surfaces of the cerium-zirconium composite oxide, and the existing form is one or more of an oxide, nitrogen-containing compound, fluoride, phosphate, and sulfate.

[0038] Generally speaking, through grain boundary and surface doping, the grain boundaries and surfaces of the cerium-zirconium composite oxide can contain an oxide of doping element M, or one or more of a nitrogen-containing compound, fluoride, phosphate, and sulfate formed by doping element M and M and D. Further, the doping element M, or M and D, is located at the grain boundaries and surfaces of the cerium-zirconium composite oxide, and the existing form is one or more of an oxide, nitrogen-containing compound, fluoride, phosphate, and sulfate. Further, the M element is preferably at least one of La, Pr, Nd, Y, Sc, Cu, Mn, Hf, Mg, Ba, and Sr at the grain boundaries and surfaces of the cerium-zirconium composite oxide, and the molar ratio of the M element at the grain boundaries and surfaces is 10% - 70%. The D element is preferably at least one of N and S at the grain boundaries and surfaces, and the molar ratio of the D element at the grain boundaries and surfaces is 10% - 70%. By controlling precipitation parameters, the heat treatment temperature, roasting temperature, time, atmosphere, etc. of the product, the morphology and proportion of M and D at the grain boundaries and surfaces are regulated.

[0039] Implementing the above-mentioned grain boundary and surface doping in the cerium-zirconium composite oxide can make the oxide have abundant defects and vacancies, especially the defects at the grain boundaries are more abundant, which enhances the interaction between the doping elements and the grains, and the dopants at the grain boundaries can play roles such as dispersing and coating the cerium-zirconium grains, thereby improving the high-temperature stability of the cerium-zirconium composite oxide.

[0040] The doping element M is converted into an oxide at the grain boundaries, surfaces, and within the grains, or M combines with D to form one or more of a nitrogen-containing compound, fluoride, phosphate, and sulfate; preferably, the doping element M is converted into an oxide at the grain boundaries and surfaces of the cerium-zirconium composite oxide, or / and M combines with D to form one or more of a nitrogen-containing compound, fluoride, phosphate, and sulfate; M forms an oxide, and D combines with M to form a nitrogen-containing compound, fluoride, phosphate, sulfate, etc., which can improve the high-temperature stability of the cerium-zirconium composite oxide, regulate the pore structure, or oxygen storage capacity, etc.

[0041] The dopant element M can be one or more of rare earth elements other than cerium, transition metal elements, alkaline earth metal elements, and Al and Si; wherein, the rare earth elements can be one or more of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc, preferably one or more of La, Pr, Nd, Sm, Eu, Yb, Y, and Sc; the transition metal elements can be one or more of Cu, Mn, Ni, Fe, Zn, Co, Ti, Hf, Cr, and W; the alkaline earth metal elements can be one or more of Mg, Ca, Sr, and Ba; and more preferably, the cation dopant element M is one or more of La, Pr, Nd, Sm, Eu, Yb, Y, Sc, Cu, Mn, Hf, Fe, Co, Al, Si, Mg, Ba, and Sr. The dopant element D can be one or more of N, S, F, and P, with N and S being preferred.

[0042] The specific surface area of ​​this cerium-zirconium composite oxide is greater than 50 m² after being held at 1000℃ for 10 hours. 2 / g, preferably greater than 60m 2 / g; Specific surface area greater than 35m² after heat treatment at 1100℃ for 4 hours. 2 / g, preferably greater than 40m 2 / g. Furthermore, the total pore volume of the cerium-zirconium composite oxide is greater than 0.4 mL / g, and the total pore volume after being kept at 1000℃ for 10 h is greater than 0.2 mL / g.

[0043] A second aspect of the present invention provides a method for preparing a grain boundary and surface-doped cerium-zirconium composite oxide as described in the first aspect of the present invention, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps:

[0044] S1. Prepare aqueous solutions containing cerium ions and zirconium ions in the required stoichiometric ratio for the product, and mix them to obtain a mixed solution; carry out a precipitation reaction with an alkaline substance in a reactor, and filter, wash, dry and calcine the obtained precipitate to obtain cerium-zirconium oxide.

[0045] S2. The cerium-zirconium oxide obtained in step S1 is mixed with the liquid salt of doped element M, dried, and then subjected to one or two heat treatments, followed by one or two calcinations to obtain cerium-zirconium composite oxides with grain boundaries and surfaces doped.

[0046] In step S1, the aqueous solution containing zirconium ions can be one or a combination of more than one of zirconium oxychloride, zirconium oxynitrate, zirconium sulfate, zirconium acetate, and zirconium citrate; the aqueous solution containing cerium ions can be one or a combination of more than one of cerium chloride, cerium nitrate, cerium sulfate, cerium acetate, and cerium citrate; the alkaline substance can be at least one of magnesium bicarbonate, urea, and hydroxides, carbonates, or bicarbonates of at least one of ammonium, sodium, and potassium; preferably at least one of sodium hydroxide, urea, ammonia, and ammonium bicarbonate. During the precipitation process in step S1, the pH value is controlled between 4.5 and 14, preferably 5-11; the final pH value is controlled between 8 and 13, preferably 9-11; the reaction temperature during precipitation is 0-120℃, preferably 20-80℃; the calcination temperature in step S1 is 500-1050℃, and the time is 1-24 h; preferably, the calcination temperature is 600-950℃, and the time is 3-12 h.

[0047] The dopant element M can be added in one or both of steps S1 and S2. For example, dopant element M can be added alone in step S1 or step S2 according to the required stoichiometry of the product, or a portion can be added in step S1 and the other portion in step S2 according to the required stoichiometry of the product. Any of the above addition methods can be selected according to actual needs. The molar percentage of element M at the grain boundaries and surface of the cerium-zirconium composite oxide is 10–70 mol%. The liquid salt of dopant element M can include one or more of the following: chloride, nitrate, sulfate, acetate, citrate, amino acid salt, and molten salt or aqueous solution of organosilicon compound.

[0048] The dopant element D can also be added in one or both of steps S1 and S2, similar to the addition method of dopant element M. Any addition method can be selected according to actual needs. The molar percentage of element D at the grain boundaries and surface of the cerium-zirconium composite oxide is 10–70 mol%. Dopant element D can be added through one or more combinations of nitrates, fluorides, phosphates, and sulfates.

[0049] The heat treatment temperature in step S2 is 100-600℃ and the time is 0.5-24h; preferably, the heat treatment temperature is 150-450℃ and the time is 1-12h; furthermore, different heat treatment regimes can be adopted, such as step-by-step heat treatment, so that the doping elements can enter the grain boundaries and surfaces more uniformly and stably.

[0050] The calcination temperature in step S2 is 500–1050℃, and the time is 1–24 h; preferably, the calcination temperature is 600–950℃, and the time is 3–12 h. Furthermore, two calcinations can also be used to effectively control the particle size and dispersibility of the cerium-zirconium composite oxide, thereby further improving its high-temperature stability.

[0051] In this invention, the doping of doping elements M and D at the grain boundaries and surface of cerium-zirconium composite oxides can be achieved by mixing M and D in the form of ionic solution or liquid salt with cerium-zirconium oxide in step S2, followed by drying and then heat treatment and calcination; or by adding M and D in the form of ionic solution or liquid salt in steps S1 and S2.

[0052] A third aspect of the present invention provides a catalyst prepared using cerium-zirconium composite oxides with grain boundaries and surfaces doped as described in the first aspect of the present invention. This catalyst can be applied in fields such as vehicle exhaust purification, natural gas catalytic combustion, organic waste gas purification, and industrial flue gas denitrification.

[0053] A fourth aspect of the present invention provides the application of the catalyst described in the third aspect of the present invention in the fields of motor vehicle exhaust purification, natural gas catalytic combustion, organic waste gas purification, and industrial flue gas denitrification treatment.

[0054] The present invention will be further described below through specific embodiments.

[0055] Comparative Example 1

[0056] According to the molar distribution of cerium-zirconium composite oxide Ce 0.50 Zr 0.35 La 0.10 Y 0.05 O 1.98 A 250 mL mixture of CeCl3, ZrOCl2, LaCl3, and YCl3 with a total metal ion molar concentration of 1.5 mol / L was prepared. This mixture was then mixed with a 2.5 mol / L sodium hydroxide solution for precipitation at 25°C. The pH during precipitation was controlled at 10 ± 0.2, with a final pH of 11. The precipitate was filtered, washed, and post-treated to obtain a precursor. This precursor was then dried at 110°C for 10 hours and calcined at 800°C for 5 hours to obtain cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.353 mL / g, which decreased to 0.161 mL / g after aging at 1000°C for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after aging at 1000°C for 10 hours was 47.6 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, the specific surface area is 31.5m². 2 / g.

[0057] Comparative Example 2

[0058] According to the molar distribution of cerium-zirconium composite oxide Ce 0.80 Zr 0.10 La 0.05 Nd 0.05 O 1.97 A 250 mL mixture containing Ce(NO3)3, ZrO(NO3)2, La(NO3)3, and Nd(NO3)3 with a total metal ion molar concentration of 1.5 mol / L was prepared. This mixture was then mixed with a 2.5 mol / L ammonia solution for precipitation at 25°C. The pH during precipitation was 10 ± 0.2, and the final pH was 11. The precipitate was filtered, washed, and post-treated to obtain a precursor. This precursor was then dried at 110°C for 10 hours and calcined at 800°C for 5 hours to obtain cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.306 mL / g, which decreased to 0.148 mL / g after aging at 1000°C for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after aging at 1000°C for 10 hours was 44.7 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​30.9m². 2 / g.

[0059] Example 1

[0060] According to the molar distribution of cerium-zirconium composite oxide Ce 0.50 Zr 0.35 La 0.10 Y 0.05 O 1.98 Prepare 250 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 25℃. The pH value during the precipitation process is controlled at 10±0.2, and the final pH value of the precipitation is 11. After filtering and washing, the precipitate is processed to obtain a precursor. The precursor is then dried at 110℃ for 10 hours and calcined at 800℃ for 5 hours to obtain cerium-zirconium oxide.

[0061] According to the cerium-zirconium composite oxide Ce 0.50 Zr 0.35 La 0.10 Y 0.05 O 1.98A certain volume of a mixed solution of La(NO3)3 and Y(NO3)3 with a total metal ion concentration of 1.6 mol / L was prepared by molar proportioning. This La(NO3)3 and Y(NO3)3 mixed solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 200℃ for 2 hours, followed by calcination at 600℃ for 5 hours to obtain a cerium-zirconium composite oxide. Both La and Y atoms were present as oxides at the grain boundaries and surface. The total pore volume of the cerium-zirconium composite oxide was 0.458 mL / g, which decreased to 0.230 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 53.2 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​36.4m². 2 / g.

[0062] Example 2

[0063] According to the molar distribution of cerium-zirconium composite oxide Ce 0.80 Zr 0.10 La 0.05 Nd 0.05 O 1.97 Prepare 250 mL of a mixed solution containing Ce(NO3)3 and ZrO(NO3)2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 25℃. The pH value during the precipitation process is controlled at 10±0.2, and the final pH value of the precipitation is 11. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 800℃ for 5 hours to obtain cerium-zirconium oxide.

[0064] According to the cerium-zirconium composite oxide Ce 0.80 Zr 0.10 La 0.05 Nd 0.05 O 1.97 A certain volume of a mixed solution of La(NO3)3 and Nd(NO3)3 with a total metal ion concentration of 1.1 mol / L was prepared by molar distribution. This La(NO3)3 and Nd(NO3)3 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 300℃ for 1 hour, followed by calcination at 800℃ for 3 hours to obtain a cerium-zirconium composite oxide. La and Nd were present as oxides at the grain boundaries and surface. The total pore volume of the cerium-zirconium composite oxide was 0.423 mL / g, which decreased to 0.209 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 50.8 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​35.6m². 2 / g.

[0065] Example 3

[0066] According to the molar distribution of cerium-zirconium composite oxide Ce 0.40 Zr 0.50 La 0.05 Nd 0.05 O 1.96 Prepare 250 mL of a mixed solution containing Ce(NO3)3 and ZrO(NO3)2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 45℃. The pH value during the precipitation process is controlled at 6±0.2, and the final pH value of the precipitation is 9.5. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 800℃ for 5 hours to obtain cerium-zirconium oxide.

[0067] A certain volume of a mixed solution of La(NO3)3 and Nd(NO3)3 with a total metal ion concentration of 2.5 mol / L was prepared according to the molar ratio of cerium-zirconium composite oxide. This La(NO3)3 and Nd(NO3)3 mixed solution was then uniformly mixed with the aforementioned cerium-zirconium oxide. After drying, the mixture was heat-treated at 300℃ for 5 hours, followed by calcination at 800℃ for 3 hours to obtain the cerium-zirconium composite oxide. La and Nd were located in oxide form at the grain boundaries and surface. The total pore volume of the cerium-zirconium composite oxide was 0.433 mL / g, which decreased to 0.229 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 53.8 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​36.6m². 2 / g.

[0068] Example 4

[0069] According to the molar distribution of cerium-zirconium composite oxide Ce 0.25 Zr 0.65 La 0.05 Y 0.05 O 1.97Prepare 250 mL of a mixed solution containing Ce(NO3)3, La(NO3)3, and ZrO(NO3)2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 55℃. The pH value during the precipitation process is controlled at 6±0.2, and the final pH value of the precipitation is 9.5. After filtering and washing, the precipitate is processed to obtain a precursor. The precursor is then dried at 110℃ for 10 hours and calcined at 750℃ for 5 hours to obtain lanthanum-containing cerium zirconium oxide.

[0070] A certain volume of 2.5 mol / L Y(NO3)3 solution was prepared according to the molar ratio of cerium-zirconium composite oxide. The Y(NO3)3 solution was then uniformly mixed with the lanthanum-containing cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 500℃ for 5 hours, followed by calcination at 850℃ for 3 hours to obtain the cerium-zirconium composite oxide. Y is present as an oxide at the grain boundaries and surface. The total pore volume of the cerium-zirconium composite oxide was 0.483 mL / g, which decreased to 0.249 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 57.8 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​38.6m². 2 / g.

[0071] Example 5

[0072] According to the molar distribution of cerium-zirconium composite oxide Ce 0.80 Zr 0.05 Nd 0.15 O 1.95 S 0.05 Prepare 250 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.5 mol / L. Then add an appropriate amount of 1.0 mol / L sulfuric acid solution and mix thoroughly. Mix the mixed solution with 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at 25℃. The pH value during the precipitation process is 10-14, and the pH value at the precipitation endpoint is 12. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 500℃ for 10 hours to obtain cerium-zirconium oxide.

[0073] According to the cerium-zirconium composite oxide Ce 0.80 Z r0.05 Nd 0.15 O 1.95 S 0.05A certain volume of 1.50 mol / L Nd(NO3)3 solution and 0.4 mol / L (NH4)2SO4 solution were prepared by molar ratio. The Nd(NO3)3 solution and (NH4)2SO4 solution were sequentially and uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 200℃ for 24 hours, followed by calcination at 600℃ for 6 hours to obtain a cerium-zirconium composite oxide. The oxide contains Nd and S at its grain boundaries and surface, existing as neodymium oxide and neodymium sulfate, respectively. The total pore volume of the cerium-zirconium composite oxide was 0.402 mL / g, which decreased to 0.204 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 50.2 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​35.1m². 2 / g.

[0074] Example 6

[0075] According to the molar distribution of cerium-zirconium composite oxide Ce 0.40 Zr 0.40 La 0.05 Nd 0.10 Y 0.05 O 1.96 Prepare 270 mL of a mixed solution containing Ce(NO3)3, ZrO(NO3)2, and La(NO3)3 with a total metal ion molar concentration of 1.4 mol / L. Mix this mixed solution with a 2.4 mol / L ammonium bicarbonate solution to carry out a precipitation reaction at a precipitation temperature of 30℃. The pH value during the precipitation process is 7±0.2, and the pH value at the precipitation endpoint is 8. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 500℃ for 24 hours to obtain cerium-zirconium oxide.

[0076] According to the cerium-zirconium composite oxide Ce 0.40 Zr 0.40 La 0.05 Nd 0.10 Y 0.05 O 1.96A certain volume of a mixed solution of Nd(NO3)3 and Y(NO3)3 with a total metal ion concentration of 1.6 mol / L was prepared by molar proportioning. This Nd(NO3)3 and Y(NO3)3 mixed solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 300℃ for 12 hours, followed by calcination at 800℃ for 12 hours to obtain a cerium-zirconium composite oxide. The oxide contains Nd and Y elements at grain boundaries and on the surface, both in oxide form. The total pore volume of the cerium-zirconium composite oxide was 0.462 mL / g, which decreased to 0.236 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 54.6 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​36.8m². 2 / g.

[0077] Example 7

[0078] According to the molar distribution of cerium-zirconium composite oxide Ce 0.40 Zr 0.50 La 0.10 O 1.95 P 0.05 Prepare 290 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.3 mol / L. Mix this mixed solution with a 2.2 mol / L sodium carbonate solution to carry out a precipitation reaction at a precipitation temperature of 50℃. The pH value during the precipitation process is controlled at 9±0.2, and the final pH value of the precipitation is 10. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 600℃ for 8 hours to obtain cerium-zirconium oxide.

[0079] According to the cerium-zirconium composite oxide Ce 0.40 Zr 0.50 La 0.10 O 1.95 P 0.05 A certain volume of 1.0 mol / L La(NO3)3 solution and 0.5 mol / L ammonium phosphate solution were prepared by molar distribution. The La(NO3)3 solution and ammonium phosphate solution were then sequentially and uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 400℃ for 6 hours, followed by calcination at 800℃ for 8 hours to obtain a cerium-zirconium composite oxide. La exists in the form of oxides and phosphates at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.468 mL / g, which decreased to 0.240 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 55.1 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​37.2m². 2 / g.

[0080] Example 8

[0081] According to the molar distribution of cerium-zirconium composite oxide Ce 0.333 Zr 0.581 La 0.044 Pr 0.042 O 1.98 Prepare 250 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 60℃. The pH value during the precipitation process is controlled at 10±0.2, and the final pH value of the precipitation is 11. After filtering and washing, the precipitate is processed to obtain a precursor. The precursor is then dried at 110℃ for 10 hours and calcined at 750℃ for 6 hours to obtain cerium-zirconium oxide.

[0082] According to the cerium-zirconium composite oxide Ce 0.333 Zr 0.581 La 0.044 Pr 0.042 O 1.98 A mixed solution of La(NO3)3 and Pr(NO3)3 with a total metal ion concentration of 1.0 mol / L was prepared by molar distribution. This La(NO3)3 and Pr(NO3)3 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 300℃ for 6 hours, followed by calcination at 800℃ for 6 hours to obtain a cerium-zirconium composite oxide. La and Pr exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.523 mL / g, which decreased to 0.259 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 56.9 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​40.2m². 2 / g.

[0083] Example 9

[0084] According to the molar distribution of cerium-zirconium composite oxide Ce 0.373 Zr 0.520 La 0.044 Y 0.063 O 1.98Prepare 250 mL of a mixed solution containing Ce(NO3)3, ZrO(NO3)2, and La(NO3)3 (50% of the total required La) with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 3.0 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 30℃. The pH value during the precipitation process is 9-12, and the pH value at the precipitation endpoint is 9. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 700℃ for 8 hours to obtain cerium-zirconium oxide.

[0085] According to the cerium-zirconium composite oxide Ce 0.373 Zr 0.520 La 0.044 Y 0.063 O 1.98 A certain volume of a mixed solution of La(NO3)3 (50% of the total required La) and Y(NO3)3 with a total metal ion concentration of 1.0 mol / L was prepared. This La(NO3)3 and Y(NO3)3 mixed solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 350℃ for 6 hours, followed by calcination at 700℃ for 8 hours to obtain a cerium-zirconium composite oxide. La and Y exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.491 mL / g, which decreased to 0.248 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 55.8 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​37.9m². 2 / g.

[0086] Example 10

[0087] According to the molar distribution of cerium-zirconium composite oxide Ce 0.55 Zr 0.25 La 0.15 Cu 0.05 O 1.95 Prepare 380 mL of a mixed solution containing Ce(NO3)3 and ZrO(NO3)2 with a total metal ion molar concentration of 1.0 mol / L. Mix this solution with a 2.2 mol / L urea solution and add it to an autoclave. Slowly raise the temperature to 120°C and perform a hydrothermal reaction for 8 hours. After filtration and washing, the precipitate is processed to obtain a precursor. The precursor is then dried at 110°C for 10 hours and calcined at 800°C for 5 hours to obtain cerium-zirconium oxide.

[0088] According to the cerium-zirconium composite oxide Ce 0.55 Zr 0.25 La 0.15 Cu0.05 O 1.95 A mixed solution of La(NO3)3 and Cu(NO3)2 with a total metal ion concentration of 2.2 mol / L was prepared by molar proportioning. This La(NO3)3 and Cu(NO3)2 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 600℃ for 0.5 hours, followed by calcination at 1050℃ for 1 hour to obtain a cerium-zirconium composite oxide. La and Cu exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.443 mL / g, which decreased to 0.219 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 51.7 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​35.8m². 2 / g.

[0089] Example 11

[0090] According to the molar distribution of cerium-zirconium composite oxide Ce 0.50 Zr 0.35 Ba 0.05 Mn 0.10 O 1.96 Prepare 320 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.2 mol / L. Mix this mixed solution with a 2.1 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 90℃. The pH value during the precipitation process is 12-14, and the pH value at the precipitation endpoint is 13. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 1050℃ for 1 hour to obtain cerium-zirconium oxide.

[0091] According to the cerium-zirconium composite oxide Ce 0.50 Zr 0.35 Ba 0.05 Mn 0.10 O 1.96A mixed solution of Ba(NO3)2 and Mn(NO3)2 with a total metal ion concentration of 1.6 mol / L was prepared by molar distribution. This Ba(NO3)2 and Mn(NO3)2 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 400℃ for 6 hours, followed by calcination at 700℃ for 8 hours to obtain a cerium-zirconium composite oxide. Ba and Mn exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.451 mL / g, which decreased to 0.224 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 52.8 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​36.2m². 2 / g.

[0092] Example 12

[0093] According to the molar distribution of cerium-zirconium composite oxide Ce 0.330 Zr 0.580 La 0.033 Nd 0.032 Y 0.025 O 1.97 Prepare 250 mL of a mixed solution containing CeCl3, ZrOCl2, and LaCl3 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 45℃. The pH value during the precipitation process is controlled at 10±0.2, and the final pH value of the precipitation is 11. After filtering and washing, the precipitate is processed to obtain a precursor. The precursor is then dried at 110℃ for 10 hours and calcined at 850℃ for 5 hours to obtain cerium-zirconium oxide.

[0094] According to the cerium-zirconium composite oxide Ce 0.330 Zr 0.580 La 0.033 Nd 0.032 Y 0.025 O 1.97A mixed solution of Nd(NO3)3 and Y(NO3)3 with a total metal ion concentration of 0.7 mol / L was prepared by molar distribution. This Nd(NO3)3 and Y(NO3)3 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 350℃ for 6 hours, followed by calcination at 850℃ for 5 hours to obtain a cerium-zirconium composite oxide. The cerium-zirconium composite oxide contains Nd and Y elements at its grain boundaries and surface, both in oxide form. The total pore volume of the cerium-zirconium composite oxide was 0.548 mL / g, which decreased to 0.276 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 57.1 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​40.9m². 2 / g.

[0095] Example 13

[0096] According to the molar distribution of cerium-zirconium composite oxide Ce 0.18 Zr 0.64 La 0.03 Y 0.15 O 1.96 Prepare 250 mL of a mixed solution containing CeCl3, ZrOCl2, and YCl3 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 50℃. The pH value during the precipitation process is 10–14, and the pH value at the precipitation endpoint is 10.5. After filtering and washing, the precipitate is processed to obtain a precursor. The precursor is then dried at 110℃ for 10 hours and calcined at 650℃ for 8 hours to obtain cerium-zirconium oxide.

[0097] According to the cerium-zirconium composite oxide Ce 0.18 Zr 0.64 La 0.03 Y 0.15 O 1.96 A certain volume of 0.5 mol / L La(NO3)3 solution was prepared by molar distribution. The La(NO3)3 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 200℃ for 10 hours, followed by calcination at 650℃ for 8 hours to obtain a cerium-zirconium composite oxide. La exists in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.582 mL / g, which decreased to 0.286 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 57.9 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​43.8m². 2 / g.

[0098] Example 14

[0099] According to the molar distribution of cerium-zirconium composite oxide Ce 0.16 Zr 0.78 La 0.02 Nd 0.04 O 1.98 Prepare 250 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 80℃. The pH value during the precipitation process is 10-14, and the pH value at the precipitation endpoint is 10. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 600℃ for 10 hours to obtain cerium-zirconium oxide.

[0100] According to the cerium-zirconium composite oxide Ce 0.16 Zr 0.78 La 0.02 Nd 0.04 O 1.98 A mixed solution of La(NO3)3 and Nd(NO3)3 with a total metal ion concentration of 0.7 mol / L was prepared by molar distribution. This La(NO3)3 and Nd(NO3)3 solution was then uniformly mixed with the previously obtained cerium-zirconium oxide. After drying, the mixture was heat-treated at 400℃ for 6 hours, followed by calcination at 600℃ for 12 hours to obtain a cerium-zirconium composite oxide. La and Nd exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.591 mL / g, which decreased to 0.289 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 60.2 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​45.1m². 2 / g.

[0101] Example 15

[0102] According to the molar distribution of cerium-zirconium composite oxide Ce 0.40 Zr 0.40 Al 0.20 O 1.93 N 0.08Prepare 320 mL of a mixed solution containing Ce(NO3)3 and ZrO(NO3)2 with a total metal ion molar concentration of 1.2 mol / L. Mix this mixed solution with a 2.2 mol / L ammonia / ammonium bicarbonate solution to carry out a precipitation reaction at 30℃. The pH value during the precipitation process is 7.5-8.5, and the pH value at the precipitation endpoint is 8. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 950℃ for 4 hours to obtain cerium-zirconium oxide.

[0103] According to the cerium-zirconium composite oxide Ce 0.40 Zr 0.40 Al 0.20 O 1.93 N 0.08 A certain volume of 2.2 mol / L Al(NO3)3 solution and 0.8 mol / L NH4NO3 solution were prepared by molar ratio. The Al(NO3)3 solution and NH4NO3 solution were then sequentially and uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 300℃ for 8 hours, followed by calcination at 800℃ for 6 hours to obtain a cerium-zirconium composite oxide. Al exists in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide, while N exists as a nitrogen-containing compound at the grain boundaries and surface. The total pore volume of the cerium-zirconium composite oxide was 0.611 mL / g, which decreased to 0.301 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 62.4 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​46.3m². 2 / g.

[0104] Example 16

[0105] According to the molar distribution of cerium-zirconium composite oxide Ce 0.60 Zr 0.30 Ba 0.10 O 1.98 F 0.01 Prepare 380 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.0 mol / L. Mix this mixed solution with a 2.3 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 20℃. The pH value during the precipitation process is 4.5-10, and the pH value at the precipitation endpoint is 11. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 700℃ for 8 hours to obtain cerium-zirconium oxide.

[0106] According to the cerium-zirconium composite oxide Ce 0.60 Zr 0.30 Ba0.10 O 1.98 F 0.01 A certain volume of 1.0 mol / L Ba(NO3)2 solution and 0.1 mol / L NH4F solution were prepared by molar fractionation. The Ba(NO3)2 solution and NH4F solution were then sequentially and uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 150℃ for 12 hours, followed by calcination at 600℃ for 12 hours to obtain a cerium-zirconium composite oxide. Ba exists as an oxide at the grain boundaries and surface of the cerium-zirconium composite oxide, while F exists as a fluoride at the grain boundaries and surface. The total pore volume of the cerium-zirconium composite oxide was 0.450 mL / g, which decreased to 0.222 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 52.2 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​36.2m². 2 / g.

[0107] Example 17

[0108] According to the molar distribution of cerium-zirconium composite oxide Ce 0.45 Zr 0.35 Y 0.15 Mg 0.05 O 1.96 Prepare 250 mL of a mixed solution containing Ce(NO3)3, ZrO(NO3)2, and Y(NO3)3 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 3.0 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 30℃. The pH value during the precipitation process is 9-12, and the pH value at the precipitation endpoint is 9. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 950℃ for 3 hours to obtain cerium-zirconium oxide.

[0109] According to the cerium-zirconium composite oxide Ce 0.45 Zr 0.35 Y 0.15 Mg 0.05 O 1.96A certain volume of 0.5 mol / L Mg(NO3)2 solution was prepared by molar proportioning. The Mg(NO3)2 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 250℃ for 10 hours, followed by calcination at 900℃ for 5 hours to obtain a cerium-zirconium composite oxide. Mg element exists in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.438 mL / g, which decreased to 0.221 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 52.9 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​36.1m². 2 / g.

[0110] Example 18

[0111] According to the molar distribution of cerium-zirconium composite oxide Ce 0.40 Zr 0.45 Pr 0.10 Sm 0.05 O 1.97 Prepare 470 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 0.8 mol / L. Mix this mixed solution with a 1.0 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 50℃. The pH value during the precipitation process is 5-9, and the pH value at the precipitation endpoint is 10. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 500℃ for 16 hours to obtain cerium-zirconium oxide.

[0112] According to the cerium-zirconium composite oxide Ce 0.40 Zr 0.45 Pr 0.10 Sm 0.05 O 1.97 A mixed solution of Pr(NO3)3 and Sm(NO3)3 with a total metal ion concentration of 1.6 mol / L was prepared by molar distribution. This solution was then uniformly mixed with the previously obtained cerium-zirconium oxide. After drying, the mixture was heat-treated at 300℃ for 8 hours, followed by calcination at 500℃ for 24 hours to obtain a cerium-zirconium composite oxide. Pr and Sm elements exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.451 mL / g, which decreased to 0.235 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 54.8 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​36.9m². 2 / g.

[0113] Example 19

[0114] According to the molar distribution of cerium-zirconium composite oxide Ce 0.20 Zr 0.60 Eu 0.10 Co 0.10 O 1.98 Prepare 250 mL of a mixed solution containing Ce(NO3)3 and ZrO(NO3)2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 3.0 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 35℃. The pH value during the precipitation process is 9-12, and the pH value at the precipitation endpoint is 9. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 600℃ for 12 hours to obtain cerium-zirconium oxide.

[0115] According to the cerium-zirconium composite oxide Ce 0.20 Zr 0.60 Eu 0.10 Co 0.10 O 1.98 A mixed solution of Eu(NO3)3 and Co(NO3)2 with a total metal ion concentration of 2.2 mol / L was prepared by molar distribution. This Eu(NO3)3 and Co(NO3)2 solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 450℃ for 1 hour, followed by calcination at 800℃ for 6 hours to obtain a cerium-zirconium composite oxide. Eu and Co elements exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.552 mL / g, which decreased to 0.279 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 57.3 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​42.5m². 2 / g.

[0116] Example 20

[0117] According to the molar distribution of cerium-zirconium composite oxide Ce 0.90 Zr 0.05 Gd 0.03 Yb 0.02 O 1.97Prepare 290 mL of a mixed solution containing Ce(NO3)3 and ZrO(NO3)2 with a total metal ion molar concentration of 1.3 mol / L. Mix this mixed solution with a 3.0 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 20℃. The pH value during the precipitation process is 9-12, and the pH value at the precipitation endpoint is 9. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 550℃ for 12 hours to obtain cerium-zirconium oxide.

[0118] According to the cerium-zirconium composite oxide Ce 0.90 Zr 0.05 Gd 0.03 Yb 0.02 O 1.97 A mixed solution of Gd(NO3)3 and Yb(NO3)3 with a total metal ion concentration of 0.6 mol / L was prepared by molar distribution. This solution was then uniformly mixed with the previously obtained cerium-zirconium oxide. After drying, the mixture was heat-treated at 350℃ for 7 hours, followed by calcination at 600℃ for 12 hours to obtain a cerium-zirconium composite oxide. This oxide contains Gd and Yb elements at its grain boundaries and surface, both in oxide form. The total pore volume of the cerium-zirconium composite oxide was 0.406 mL / g, which decreased to 0.210 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 50.4 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​35.3m². 2 / g.

[0119] Example 21

[0120] According to the molar distribution of cerium-zirconium composite oxide Ce 0.70 Zr 0.20 Fe 0.04 Ba 0.04 Sc 0.02 O 1.98 Prepare 250 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 80℃. The pH value during the precipitation process is 10-14, and the pH value at the precipitation endpoint is 10. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 600℃ for 12 hours to obtain cerium-zirconium oxide.

[0121] According to the cerium-zirconium composite oxide Ce 0.70 Zr 0.20 Fe 0.04 Ba0.04 Sc 0.02 O 1.98 A mixed solution of Fe(NO3)3, Ba(NO3)2, and Sc(NO3)3 with a total metal ion concentration of 1.1 mol / L was prepared by molar distribution. This Fe(NO3)3, Ba(NO3)2, and Sc(NO3)3 mixed solution was then uniformly mixed with the previously obtained cerium-zirconium oxide. After drying, the mixture was heat-treated at 300℃ for 8 hours, followed by calcination at 800℃ for 7 hours to obtain a cerium-zirconium composite oxide. This composite oxide contains Fe, Ba, and Sc elements at its grain boundaries and surface, all in oxide form. The total pore volume of the cerium-zirconium composite oxide was 0.431 mL / g, which decreased to 0.217 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 51.6 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​35.7m². 2 / g.

[0122] Example 22

[0123] According to the molar distribution of cerium-zirconium composite oxide Ce 0.50 Zr 0.45 Mn 0.05 O 1.99 Prepare 250 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction. The precipitation temperature is 0℃, the pH value is controlled at 9±0.2 during the precipitation process, and the pH value at the precipitation endpoint is 11. After filtering, washing and other post-treatments, the precipitate is obtained as a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 450℃ for 18 hours to obtain cerium-zirconium oxide.

[0124] According to the cerium-zirconium composite oxide Ce 0.50 Zr 0.45 Mn 0.05 O 1.99 A certain volume of molten Mn(NO3)2 salt solution was prepared by molar proportioning. An appropriate amount of the molten Mn(NO3)2 salt solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 600℃ for 0.5 hours, followed by calcination at 950℃ for 3 hours to obtain a cerium-zirconium composite oxide. This oxide contains Mn elements at its grain boundaries and surface, existing in oxide form. The total pore volume of the cerium-zirconium composite oxide was 0.404 mL / g, which decreased to 0.206 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 50.3 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​35.2m². 2 / g.

[0125] Example 23

[0126] According to the molar distribution of cerium-zirconium composite oxide Ce 0.40 Zr 0.45 Si 0.10 Hf 0.02 Sr 0.03 O 1.98 Prepare 250 mL of a mixed solution containing Ce(NO3)3 and ZrO(NO3)2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 3.0 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 30℃. The pH value during the precipitation process is controlled at 9.0±0.2, and the final pH value of the precipitation is 10. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 650℃ for 10 hours to obtain cerium-zirconium oxide.

[0127] According to the cerium-zirconium composite oxide Ce 0.40 Zr 0.45 Si 0.10 Hf 0.02 Sr 0.03 O 1.98 A mixed solution of tetraethyl orthosilicate, Sr(NO3)2, and HfO(NO3)2 with a total metal ion concentration of 1.6 mol / L was prepared by molar proportioning. This mixed solution was then uniformly mixed with the previously obtained cerium-zirconium oxide. After drying, the mixture was heat-treated at 350℃ for 7 hours, followed by calcination at 800℃ for 5 hours to obtain a cerium-zirconium composite oxide. This composite oxide contains Si, Sr, and Hf elements at its grain boundaries and surface, all in oxide form. The total pore volume of the cerium-zirconium composite oxide was 0.467 mL / g, which decreased to 0.229 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 54.9 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​37.3m². 2 / g.

[0128] Example 24

[0129] According to the molar distribution of cerium-zirconium composite oxide Ce 0.333 Zr 0.581 La 0.044 Pr 0.042 O 1.98Prepare 250 mL of a mixed solution containing CeCl3 and ZrOCl2 with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 2.5 mol / L sodium hydroxide solution to carry out a precipitation reaction at a precipitation temperature of 60℃. The pH value during the precipitation process is controlled at 10±0.2, and the final pH value of the precipitation is 11. After filtering and washing, the precipitate is processed to obtain a precursor. The precursor is then dried at 110℃ for 10 hours and calcined at 750℃ for 6 hours to obtain cerium-zirconium oxide.

[0130] According to the cerium-zirconium composite oxide Ce 0.333 Zr 0.581 La 0.044 Pr 0.042 O 1.98 A mixed solution of La(NO3)3 and Pr(NO3)3 with a total metal ion concentration of 1.0 mol / L was prepared by molar distribution. This La(NO3)3 and Pr(NO3)3 solution was then uniformly mixed with the previously obtained cerium-zirconium oxide. After drying, the mixture was heat-treated at 250℃ for 4 hours, then further heated to 400℃ for 5 hours, and finally calcined at 800℃ for 6 hours to obtain a cerium-zirconium composite oxide. La and Pr exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.551 mL / g, which decreased to 0.279 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 57.8 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​41.1m². 2 / g.

[0131] Example 25

[0132] According to the molar distribution of cerium-zirconium composite oxide Ce 0.373 Zr 0.520 La 0.044 Y 0.063 O 1.98 Prepare 250 mL of a mixed solution containing Ce(NO3)3, ZrO(NO3)2, and La(NO3)3 (50% of the total required La) with a total metal ion molar concentration of 1.5 mol / L. Mix this mixed solution with a 3.0 mol / L ammonia solution to carry out a precipitation reaction at a precipitation temperature of 30℃. The pH value during the precipitation process is 9-12, and the pH value at the precipitation endpoint is 9. After filtering and washing, the precipitate is processed to obtain a precursor. Then, the precursor is dried at 110℃ for 10 hours and calcined at 700℃ for 8 hours to obtain cerium-zirconium oxide.

[0133] According to the cerium-zirconium composite oxide Ce 0.373 Zr 0.520La 0.044 Y 0.063 O 1.98 A mixed solution of La(NO3)3 (50% of the total required La) and Y(NO3)3 with a total metal ion concentration of 1.0 mol / L was prepared by molar proportioning. This La(NO3)3 and Y(NO3)3 mixed solution was then uniformly mixed with the cerium-zirconium oxide obtained above. After drying, the mixture was heat-treated at 200℃ for 5 hours, then at 450℃ for 3 hours, followed by calcination at 650℃ for 5 hours, and finally at 800℃ for 3 hours to obtain a cerium-zirconium composite oxide. La and Y exist in oxide form at the grain boundaries and surface of the cerium-zirconium composite oxide. The total pore volume of the cerium-zirconium composite oxide was 0.501 mL / g, which decreased to 0.254 mL / g after high-temperature aging at 1000℃ for 10 hours. The specific surface area of ​​the cerium-zirconium composite oxide after high-temperature aging at 1000℃ for 10 hours was 56.3 m². 2 / g, after high-temperature aging at 1100℃ for 4 hours, has a specific surface area of ​​38.4m². 2 / g.

[0134] As can be seen from the data provided in the above embodiments, the total pore volume of the cerium-zirconium composite oxide obtained by the preparation method of the present invention and the total pore volume after high-temperature aging at 1000℃ for 10 hours are significantly higher than those obtained by the comparative preparation method. The specific surface area of ​​the cerium-zirconium composite oxide obtained by the preparation method of the present invention after high-temperature aging at 1000℃ for 10 hours and after high-temperature aging at 1100℃ for 4 hours are both higher than those obtained by the comparative preparation method. The cerium-zirconium composite oxide obtained by the preparation method of the present invention can achieve excellent high-temperature stability.

[0135] In summary, this invention relates to a grain boundary and surface-doped cerium-zirconium composite oxide, its preparation method, and its applications, improving the high-temperature stability and catalytic performance of the cerium-zirconium composite oxide. The cerium-zirconium composite oxide provided by this invention contains dopant elements at its grain boundaries and surface; more specifically, the dopant elements are located at its grain boundaries and surface, increasing the number of defects and vacancies, enhancing oxygen migration capacity, and exhibiting good high-temperature stability. Furthermore, this cerium-zirconium composite oxide can inhibit the migration, aggregation, and growth of noble metal particles, enhancing the high-temperature stability of noble metal catalysts, and can be applied in fields such as motor vehicle exhaust purification, natural gas catalytic combustion, organic waste gas purification, and industrial flue gas denitrification.

[0136] 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 cerium-zirconium composite oxide doped at grain boundaries and on the surface, characterized in that, The chemical formula of the cerium-zirconium composite oxide is Ce. x Zr 1-x-y M y O 2-α D δ ;in, M represents a cation-doped element, and D represents an anion-doped element; 0.1≤x≤0.9, 0 <y≤0.2,0≤α≤0.1,0<δ≤0.1; The cerium-zirconium composite oxide contains oxides of doped element M and one or more of nitrogen-containing compounds, fluorides, phosphates, and sulfates formed by M and D at the grain boundaries and surface; the doped element M is one or more of rare earth elements other than cerium, transition metal elements, alkaline earth metal elements, and Al and Si; the doped element D is one or more of N, S, F, and P.

2. The cerium-zirconium composite oxide with grain boundary and surface doping according to claim 1, characterized in that, The rare earth element is one or more of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc; the transition metal element is one or more of Cu, Mn, Ni, Fe, Zn, Co, Ti, Hf, Cr, and W; and the alkaline earth metal element is one or more of Mg, Ca, Sr, and Ba.

3. The cerium-zirconium composite oxide with grain boundary and surface doping according to claim 2, characterized in that, The cation doping element M is one or more of La, Pr, Nd, Sm, Eu, Yb, Y, Sc, Cu, Mn, Hf, Fe, Co, Al, Si, Mg, Ba and Sr.

4. The cerium-zirconium composite oxide with grain boundary and surface doping according to any one of claims 1-3, characterized in that, The specific surface area of ​​the cerium-zirconium composite oxide after being kept at 1000℃ for 10 hours is greater than 50 m². 2 / g; Specific surface area greater than 35m² after heat treatment at 1100℃ for 4 hours. 2 / g.

5. The cerium-zirconium composite oxide with grain boundary and surface doping according to claim 4, characterized in that, The total pore volume of the cerium-zirconium composite oxide is greater than 0.4 mL / g, and the total pore volume after being kept at 1000℃ for 10 h is greater than 0.2 mL / g.

6. The cerium-zirconium composite oxide with grain boundary and surface doping according to claim 4, characterized in that, The specific surface area of ​​the cerium-zirconium composite oxide after being heated at 1000℃ for 10 hours is greater than 60 m². 2 / g; Specific surface area greater than 40m² after heat treatment at 1100℃ for 4 hours. 2 / g.

7. A method for preparing a grain boundary and surface-doped cerium-zirconium composite oxide as described in any one of claims 1-6, characterized in that, Including the following steps: S1. Prepare aqueous solutions containing cerium ions and zirconium ions in the required stoichiometric ratio for the product, and mix them to obtain a mixed solution; carry out a precipitation reaction with an alkaline substance in a reactor, and filter, wash, dry and calcine the obtained precipitate to obtain cerium-zirconium oxide. S2. The cerium-zirconium oxide obtained in step S1 is mixed with the liquid salt of doped element M, dried, and then subjected to one or two heat treatments, followed by one or two calcinations to obtain cerium-zirconium composite oxides doped at grain boundaries and surfaces. In this process, 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, The aqueous solution containing zirconium ions in step S1 includes one or more of the following: zirconium oxychloride, zirconium oxynitrate, zirconium sulfate, zirconium acetate, and zirconium citrate.

9. The method according to claim 7, characterized in that, The aqueous solution containing cerium ions in step S1 includes one or more of the following: cerium chloride, cerium nitrate, cerium sulfate, cerium acetate, and cerium citrate.

10. The method according to claim 7, characterized in that, The alkaline substance 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 reaction temperature during the precipitation process is between 0 and 120°C.

12. The method according to claim 7, characterized in that, The liquid salt of the dopant element M includes one or more of the following: molten salts or aqueous solutions of chlorides, nitrates, sulfates, acetates, citrates, amino acid salts, and organosilicon compounds.

13. The method according to claim 7, characterized in that, The dopant element M is added in one or both of steps S1 and S2.

14. The method according to claim 7, characterized in that, The dopant element D is added by one or more of nitrates, fluorides, phosphates and sulfates.

15. The method according to claim 7, characterized in that, The calcination temperature in step S1 is 500–1050°C, and the time is 1–24 hours.

16. The method according to claim 7, characterized in that, The heat treatment temperature in step S2 is 100–600°C, and the time is 0.5–24 h.

17. The method according to claim 7, characterized in that, The roasting temperature in step S2 is 500–1050°C, and the time is 1–24 hours.

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

19. 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 reaction temperature during the precipitation process is 20-80℃.

20. The method according to claim 15, characterized in that, The roasting temperature in step S1 is 600–950°C, and the time is 3–12 hours.

21. The method according to claim 16, characterized in that, The heat treatment temperature in step S2 is 150–450°C, and the time is 1–12 hours.

22. The method according to claim 17, characterized in that, The roasting temperature in step S2 is 600–950°C, and the time is 3–12 hours.

23. A catalyst, characterized in that, It is prepared using cerium-zirconium composite oxides with grain boundaries and surface doping as described in any one of claims 1-6.

24. The application of the catalyst as described in claim 23 in the fields of motor vehicle exhaust purification, natural gas catalytic combustion, organic waste gas purification, and industrial flue gas denitrification treatment.

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