Cerium-based high-entropy oxide as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a cerium-based high-entropy oxide and a preparation method and application thereof. The invention provides a cerium-based high-entropy oxide, the chemical composition of the cerium-based high-entropy oxide is CeZrPrAROx, A and R are independently Nd, La, Y, Cu, Zn, Mn, Al, Ti or Fe, and the A and the R are different; the molar ratio of Ce to Zr to Pr to A to R is (1-5): (1-5): (1-4): (1-4): (1-4); and the value range of x is 1.5 to 2. The cerium-based high-entropy oxide catalyst is prepared by regulating and controlling the types and doping amounts of the doping elements, and the catalytic purification capacity of a traditional cerium-based composite oxide catalyst on internal combustion engine tail gas particulate matter can be further improved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a cerium-based high-entropy oxide, its preparation method, and its application. Background Technology

[0002] High-entropy composite oxides, due to their rich constituent elements and high-entropy effect, typically possess properties such as high temperature resistance and strong mechanical stability. They also exhibit abundant active sites, stable crystal structures, and excellent specific surface area controllability.

[0003] Rare earth metal oxides exhibit high activity in the combustion of carbon soot and are widely used in the preparation of catalysts for the purification of internal combustion engine exhaust gases. Doping with single transition metals such as Co and Mn improves the purification soot performance of Ce-based high-entropy oxides. However, the catalytic performance of the doped high-entropy oxides obtained above still needs further improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a cerium-based high-entropy oxide, its preparation method, and its applications. The cerium-based high-entropy oxide provided by this invention exhibits better catalytic performance for diesel engine exhaust soot.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a cerium-based high-entropy oxide, the chemical composition of which is CeZrPrARO. x Where A and R are independently Nd, La, Y, Cu, Zn, Mn, Al, Ti, or Fe, and A and R are different; The molar ratio of Ce, Zr, Pr, A and R is 1~5:1~5:1~4:1~4:1~4; The value of x ranges from 1.5 to 2.

[0006] Preferably, A and R are Nd and La, Cu and La, Zn and La, Mn and La, Fe and La, Al and La, Cu and Y, Ti and Y, Mn and Y, Mn and Ti, Cu and Mn, or Cu and Ti.

[0007] This invention also provides a method for preparing the cerium-based high-entropy oxide described in the above technical solution, comprising the following steps: The compound corresponding to the metal element in the cerium-based high-entropy oxide is mixed with water to obtain a metal source solution; The metal source solution is calcined to obtain the cerium-based high-entropy oxide.

[0008] Preferably, the compound corresponding to Ce includes at least one of cerium nitrate, cerium acetate, cerium carbonate, cerium ammonium nitrate, cerium ammonium acetate, and cerium ammonium carbonate; The compounds corresponding to Zr include at least one of zirconium nitrate, zirconium acetate, zirconium oxynitrate, zirconium carbonate, ammonium zirconium carbonate, and potassium zirconium carbonate; The compounds corresponding to Pr include at least one of praseodymium nitrate, praseodymium hydroxide, praseodymium acetate, praseodymium chloride, praseodymium iodide, praseodymium acetate, praseodymium sulfate, praseodymium perchlorate, praseodymium phosphate, praseodymium oxalate, and praseodymium carbonate. The compounds corresponding to Nd include at least one of neodymium nitrate, neodymium hydroxide, neodymium acetate, neodymium chloride, neodymium iodide, neodymium acetate, neodymium sulfate, neodymium perchlorate, neodymium phosphate, neodymium oxalate, and neodymium carbonate; The compounds corresponding to La include at least one of lanthanum nitrate, lanthanum hydroxide, lanthanum acetate, lanthanum chloride, lanthanum iodide, lanthanum acetate, lanthanum sulfate, lanthanum perchlorate, lanthanum phosphate, lanthanum oxalate, and lanthanum carbonate. The compound corresponding to Y includes at least one of yttrium nitrate, yttrium hydroxide, yttrium acetate, yttrium chloride, yttrium iodide, yttrium acetate, yttrium sulfate, yttrium perchlorate, yttrium phosphate, yttrium oxalate, and yttrium carbonate; The compounds corresponding to Cu include at least one of copper nitrate, copper hydroxide, copper acetate, copper chloride, copper iodide, copper acetate, copper sulfate, copper perchlorate, copper phosphate, copper oxalate, and copper carbonate. The compounds corresponding to Zn include at least one of zinc nitrate, zinc hydroxide, zinc acetate, zinc chloride, zinc acetate, zinc propionate, zinc butyrate, zinc succinate, zinc sulfate, zinc perchlorate, zinc phosphate, zinc oxalate, and zinc carbonate. The compounds corresponding to Mn include at least one of manganese nitrate, manganese hydroxide, manganese acetate, manganese chloride, manganese acetate, manganese propionate, manganese butyrate, manganese succinate, manganese sulfate, manganese perchlorate, manganese phosphate, manganese oxalate, and manganese carbonate. The compounds corresponding to Al include at least one of aluminum nitrate, aluminum hydroxide, aluminum acetate, aluminum chloride, aluminum acetate, aluminum propionate, aluminum butyrate, aluminum succinate, aluminum sulfate, aluminum perchlorate, aluminum phosphate, aluminum oxalate, and aluminum carbonate. The compounds corresponding to Ti include at least one of titanium sulfate, titanium oxysulfate, tetrabutyl titanate, isopropyl titanate, fluorotitanate, metatitanate, and titanate. The compounds corresponding to Fe include at least one of ferric nitrate, ferric hydroxide, ferric acetate, ferric chloride, ferric acetate, ferric propionate, ferric butyrate, ferric succinate, ferric sulfate, ferric perchlorate, ferric phosphate, ferric oxalate, and ferric carbonate.

[0009] Preferably, when the corresponding compound is poorly soluble in water, the compound is added in the form of a solution, and the method for preparing the solution includes: dissolving the poorly soluble compound in an acidic solution, wherein the mass concentration of the acidic solution is 10-30%.

[0010] Preferably, the total molar concentration of metal ions in the metal source solution is 0.01~5 mol / L.

[0011] Preferably, the calcination temperature is 200~800℃, and the holding time is 0.5~8h.

[0012] Preferably, the roasting is carried out in an air atmosphere.

[0013] The present invention also provides the application of the cerium-based high-entropy oxide described in the above technical solution or the cerium-based high-entropy oxide prepared by the preparation method described in the above technical solution as a catalyst in catalytic redox reactions.

[0014] Preferably, the catalytic oxidation-reduction reaction includes catalytic purification of particulate matter in internal combustion engine exhaust.

[0015] This invention provides a cerium-based high-entropy oxide, the chemical composition of which is CeZrPrARO. x Where A and R are independently Nd, La, Y, Cu, Zn, Mn, Al, Ti or Fe, and A and R are different; the molar ratio of Ce, Zr, Pr, A and R is 1~5:1~5:1~4:1~4:1~4; the value of x is in the range of 1.5~2.

[0016] This invention utilizes cerium-zirconium-praseodymium composite oxides CeZrPrO x High-entropy composite oxides based on cerium, zirconium, and praseodymium are prepared by introducing Nd, La, Y, Cu, Zn, Mn, Al, Ti, or Fe. The active sites, specific surface area, crystal structure, and electronic structure of traditional cerium, zirconium, and praseodymium composite oxides are optimized to improve their catalytic performance for diesel engine exhaust soot.

[0017] This invention also provides a method for preparing the cerium-based high-entropy oxide described above, comprising the following steps: mixing a compound corresponding to the metal element in the cerium-based high-entropy oxide with water to obtain a metal source solution; and calcining the metal source solution to obtain the cerium-based high-entropy oxide. The preparation method provided by this invention is simple, low-cost, and can reduce process pollutant emissions and increase product yield, making it suitable for industrial production. Attached Figure Description

[0018] Figure 1 XRD patterns of the high-entropy oxides in the examples and comparative examples; Figure 2 Raman diagrams of the high-entropy oxides in the examples and comparative examples; Figure 3Examples 1-6 show the catalytic purification performance of high-entropy oxides in diesel vehicle exhaust soot, where (a) is the carbon dioxide concentration and (b) is the soot particulate matter purification efficiency. Figure 4 The purification efficiency of high-entropy oxides in diesel vehicle exhaust soot particulate matter is shown in the example. Figure 5 EDS diagrams of the high-entropy oxides from Examples 1-4; Figure 6 SEM images of the high-entropy oxides from Examples 1-4; Figure 7 Transmission electron microscopy images of the high-entropy oxides of Examples 1-4; Figure 8 The following are the H2 temperature-programmed reduction graphs (a) and O2 temperature-programmed oxidation graphs (b) for Examples 1-6 and Comparative Example 1, and the soot temperature-programmed reduction graphs (c) for Examples 1-4. Figure 9 SEM image of the high-entropy oxide in Comparative Example 1; Figure 10 The image shows a transmission electron microscope (TEM) image of the high-entropy oxide from Comparative Example 1. Figure 11 The soot catalytic purification reaction performance of diesel vehicle exhaust gas is shown in Comparative Examples 1 and 2, where (a) represents carbon dioxide concentration and (b) represents soot particulate matter purification efficiency. Figure 12 The diagrams (a) and (b) are for the H2 temperature-programmed reduction and O2 temperature-programmed oxidation of Examples 7-11. Figure 13 Examples 7-11 show the catalytic purification reaction performance of diesel vehicle exhaust soot, where (a) represents carbon dioxide concentration and (b) represents soot particulate matter purification efficiency. Detailed Implementation

[0019] This invention provides a cerium-based high-entropy oxide, the chemical composition of which is CeZrPrARO. x Where A and R are independently Nd, La, Y, Cu, Zn, Mn, Al, Ti, or Fe, and A and R are different; The molar ratio of Ce, Zr, Pr, A and R is 1~5:1~5:1~4:1~4:1~4; The value of x ranges from 1.5 to 2.

[0020] In this invention, the molar ratio of Ce, Zr, Pr, A and R is 1~5:1~5:1~4:1~4:1~4, preferably 3:3:2:2:2.

[0021] In this invention, A and R are preferably Nd and La, Cu and La, Zn and La, Mn and La, Fe and La, Al and La, Cu and Y, Ti and Y, Mn and Y, Mn and Ti, Cu and Mn or Cu and Ti.

[0022] This invention also provides a method for preparing the cerium-based high-entropy oxide described in the above technical solution, comprising the following steps: The compound corresponding to the metal element in the cerium-based high-entropy oxide is mixed with water to obtain a metal source solution; The metal source solution is calcined to obtain the cerium-based high-entropy oxide.

[0023] The present invention mixes the compound corresponding to the metal element in the cerium-based high-entropy oxide with water to obtain a metal source solution.

[0024] In this invention, the compound corresponding to Ce preferably includes at least one of cerium nitrate, cerium acetate, cerium carbonate, cerium ammonium nitrate, cerium ammonium acetate, and cerium ammonium carbonate; the cerium nitrate is preferably Ce(NO3)3∙6H2O.

[0025] In this invention, the compound corresponding to Zr preferably includes at least one of zirconium nitrate, zirconium acetate, zirconium oxynitrate, zirconium carbonate, ammonium zirconium carbonate, and potassium zirconium carbonate; the zirconium nitrate is preferably Zr(NO3)4∙5H2O.

[0026] In this invention, the compound corresponding to Pr preferably includes at least one of praseodymium nitrate, praseodymium hydroxide, praseodymium acetate, praseodymium chloride, praseodymium iodide, praseodymium acetate, praseodymium sulfate, praseodymium perchlorate, praseodymium phosphate, praseodymium oxalate, and praseodymium carbonate; the praseodymium nitrate is preferably Pr(NO3)3∙6H2O.

[0027] In this invention, the compound corresponding to Nd preferably includes at least one of neodymium nitrate, neodymium hydroxide, neodymium acetate, neodymium chloride, neodymium iodide, neodymium acetate, neodymium sulfate, neodymium perchlorate, neodymium phosphate, neodymium oxalate, and neodymium carbonate; the neodymium nitrate is preferably Nd(NO3)3∙6H2O.

[0028] In this invention, the compound corresponding to La preferably includes at least one of lanthanum nitrate, lanthanum hydroxide, lanthanum acetate, lanthanum chloride, lanthanum iodide, lanthanum acetate, lanthanum sulfate, lanthanum perchlorate, lanthanum phosphate, lanthanum oxalate, and lanthanum carbonate; the lanthanum nitrate is preferably La(NO3)3∙6H2O.

[0029] In this invention, the compound corresponding to Y preferably includes at least one selected from yttrium nitrate, yttrium hydroxide, yttrium acetate, yttrium chloride, yttrium iodide, yttrium acetate, yttrium sulfate, yttrium perchlorate, yttrium phosphate, yttrium oxalate, and yttrium carbonate; the yttrium nitrate is preferably Y(NO3)3∙6H2O.

[0030] In this invention, the compound corresponding to Cu preferably includes at least one of copper nitrate, copper hydroxide, copper acetate, copper chloride, copper iodide, copper acetate, copper sulfate, copper perchlorate, copper phosphate, copper oxalate, and copper carbonate; the copper nitrate is preferably Cu(NO3)2∙3H2O.

[0031] In this invention, the compound corresponding to Zn preferably includes at least one of zinc nitrate, zinc hydroxide, zinc acetate, zinc chloride, zinc acetate, zinc propionate, zinc butyrate, zinc succinate, zinc sulfate, zinc perchlorate, zinc phosphate, zinc oxalate, and zinc carbonate; the zinc acetate is preferably C4H6O4Zn∙2H2O.

[0032] In this invention, the compound corresponding to Mn preferably includes at least one of manganese nitrate, manganese hydroxide, manganese acetate, manganese chloride, manganese acetate, manganese propionate, manganese butyrate, manganese succinate, manganese sulfate, manganese perchlorate, manganese phosphate, manganese oxalate, and manganese carbonate.

[0033] In this invention, the compound corresponding to Al preferably includes at least one of aluminum nitrate, aluminum hydroxide, aluminum acetate, aluminum chloride, aluminum acetate, aluminum propionate, aluminum butyrate, aluminum succinate, aluminum sulfate, aluminum perchlorate, aluminum phosphate, aluminum oxalate, and aluminum carbonate; the aluminum nitrate is preferably Al(NO3)3∙9H2O.

[0034] In this invention, the compound corresponding to Ti preferably includes at least one of titanium sulfate, titanium oxysulfate, tetrabutyl titanate, isopropyl titanate, fluorotitanate, metatitanate, and titanate; the titanium oxysulfate is preferably TiOSO4∙2H2O.

[0035] In this invention, the compound corresponding to Fe preferably includes at least one of ferric nitrate, ferric hydroxide, ferric acetate, ferric chloride, ferric acetate, ferric propionate, ferric butyrate, ferric succinate, ferric sulfate, ferric perchlorate, ferric phosphate, ferric oxalate, and ferric carbonate, wherein the ferric nitrate is preferably Fe(NO3)3∙9H2O.

[0036] In this invention, when the corresponding compound is sparingly soluble in water, the compound is preferably added in the form of a solution, and the method for preparing the solution preferably includes: dissolving the sparingly soluble compound in an acidic solution, wherein the mass concentration of the acidic solution is preferably 10-30%; the acidic solution is preferably a nitric acid solution.

[0037] In this invention, the mixing is preferably carried out at room temperature. The type of water used is not particularly limited and can be any type well known to those skilled in the art. In this invention, the total molar concentration of metal ions in the metal source solution is 0.01~5 mol / L, specifically 0.01 mol / L, 0.3 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L.

[0038] After obtaining the metal source solution, the present invention calcines the metal source solution to obtain the cerium-based high-entropy oxide.

[0039] In this invention, the calcination temperature is preferably 200~800℃, specifically 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, or 800℃; the holding time is 0.5~8h, specifically 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, or 8h. In this invention, the calcination is preferably carried out in an air atmosphere.

[0040] This invention also provides the application of the cerium-based high-entropy oxide described in the above-described technical solutions, or the cerium-based high-entropy oxide prepared by the preparation method described in the above-described technical solutions, as a catalyst in catalytic redox reactions. In this invention, the catalytic redox reaction preferably includes catalytic purification of particulate matter from internal combustion engine exhaust.

[0041] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0042] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0043] Example 1 A metal source solution was prepared by dissolving the following raw materials in 191.6 mL of ultrapure water at room temperature: Ce(NO3)3·6H2O (6.51 g), Zr(NO3)4·5H2O (6.44 g), Pr(NO3)3·6H2O (4.35 g), MnCO3 (1.14 g) which had been dissolved in 8.6 mL of 20% HNO3 solution beforehand, and TiOSO4·2H2O (1.96 g). The total concentration of metal ions in the solution was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. xWhere A and R are Mn and Ti; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0044] Example 2 A metal source solution was prepared by dissolving the following raw materials in 191.6 mL of ultrapure water at room temperature: Ce(NO3)3·6H2O (6.51 g), Zr(NO3)4·5H2O (6.44 g), Pr(NO3)3·6H2O (4.35 g), Cu(NO3)2·3H2O (2.42 g), and MnCO3 (1.14 g) which had been dissolved in 8.6 mL of 20% HNO3 solution. The total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. x Where A and R are Cu and Mn; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0045] Example 3 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (7.45 g), Zr(NO3)4·5H2O (7.37 g), Pr(NO3)3·6H2O (4.98 g), La(NO3)3·6H2O (4.96 g), and MnCO3 (1.32 g) which had been dissolved in 8.6 mL of 20% HNO3 solution beforehand in 191.6 mL of ultrapure water at room temperature. The total concentration of metal ions in the solution was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. x Where A and R are Mn and La; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0046] Example 4 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (7.38 g), Zr(NO3)4·5H2O (7.30 g), Pr(NO3)3·6H2O (4.93 g), La(NO3)3·6H2O (4.91 g), and Cu(NO3)2·3H2O (2.74 g) in 191.6 mL of ultrapure water at room temperature, wherein the total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO.x Where A and R are Cu and La; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0047] Example 5 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (6.51 g), Zr(NO3)4·5H2O (6.44 g), Pr(NO3)3·6H2O (4.35 g), Cu(NO3)2·3H2O (2.42 g) and TiOSO4·2H2O (1.96 g) in 191.6 mL of ultrapure water at room temperature, wherein the total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. x Where A and R are Cu and Ti; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0048] Example 6 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (6.51 g), Zr(NO3)4·5H2O (6.44 g), Pr(NO3)3·6H2O (4.35 g), Cu(NO3)2·3H2O (2.42 g), and Y(NO3)3·6H2O (3.83 g) in 191.6 mL of ultrapure water at room temperature, wherein the total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. x Where A and R are Cu and Y; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0049] Example 7 A metal source solution was prepared by dissolving the following raw materials in 191.6 mL of ultrapure water at room temperature: Ce(NO3)3·6H2O (6.51 g), Zr(NO3)4·5H2O (6.44 g), Pr(NO3)3·6H2O (4.35 g), MnCO3 (1.14 g) and Y(NO3)3·6H2O (3.83 g) which had been dissolved in 8.6 mL of 20% HNO3 solution beforehand. The total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. xWhere A and R are Mn and Y; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0050] Example 8 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (7.44 g), Zr(NO3)4·5H2O (7.36 g), Pr(NO3)3·6H2O (4.97 g), La(NO3)3·6H2O (4.95 g), and Fe(NO3)3·9H2O (4.62 g) in 228.7 mL of ultrapure water at room temperature, wherein the total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. x Where A and R are Fe and La; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0051] Example 9 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (6.51 g), Zr(NO3)4·5H2O (6.44 g), Pr(NO3)3·6H2O (4.35 g), TiOSO4·2H2O (1.96 g), and Y(NO3)3·6H2O (3.83 g) in 200.2 mL of ultrapure water at room temperature, wherein the total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. x Where A and R are Ti and Y; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0052] Example 10 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (7.70 g), Zr(NO3)4·5H2O (7.61 g), Pr(NO3)3·6H2O (4.44 g), La(NO3)3·6H2O (5.12 g), and Al(NO3)3·9H2O (5.14 g) in 236.5 mL of ultrapure water at room temperature, wherein the total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. xWhere A and R are Al and La; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0053] Example 11 A metal source solution was prepared by dissolving Ce(NO3)3·6H2O (7.36 g), Zr(NO3)4∙5H2O (7.28 g), Pr(NO3)3·6H2O (4.92 g), La(NO3)3·6H2O (4.90 g) and C4H6O4Zn·2H2O (2.48 g) in 226.2 mL of ultrapure water at room temperature, wherein the total concentration of metal ions was 0.3 mol / L. The metal source solution was calcined at 600°C for 3 hours in air to obtain a cerium-based high-entropy oxide, wherein the chemical composition of the matrix is ​​CeZrPrARO. x Where A and R are La and Zn; the molar ratio of Ce, Zr, Pr, A and R is 3:3:2:2:2; and the value of x is 2.

[0054] Comparative Example 1 CeZrPrO is commonly prepared in industry using the co-precipitation method. x Catalyst. Technical Solution: Ce(NO3)3·6H2O (11.75g), Zr(NO3)4·5H2O (14.53g), and Pr(NO3)3·6H2O (2.94g) were dissolved in 150mL of ultrapure water at 30℃ and stirred for 30 minutes to obtain solution A. 15mL of ammonia water was diluted to 300mL, and this solution was added dropwise to a large beaker at 40℃ along with solution A from the previous step to obtain solution B. The pH of solution B was precisely controlled to be 7-8 during the addition process. 7mL of hydrogen peroxide was added to solution B and stirred continuously for 10 minutes to obtain solution C. Solution C was stirred at 90℃ for 3 hours to obtain a homogeneous solution D. After solution D cooled, it was washed, filtered, and the solid E was collected. Solid E was calcined in air at 600℃ for 3 hours to obtain a high-entropy oxide.

[0055] Comparative Example 2 CeZrO prepared by traditional coprecipitation method xCatalyst. Technical solution: Ce(NO3)3·6H2O (19.30 g) and Zr(NO3)4∙5H2O (8.18 g) were dissolved in 150 mL of ultrapure water at 30 °C. After dissolution, polyvinyl alcohol (4 g) was added to the solution, and after stirring evenly, 7 mL of hydrogen peroxide was added and stirred for 30 minutes to obtain solution A. 15 mL of ammonia water was measured and diluted to 300 mL. This solution, along with solution A obtained in the previous step, was added dropwise to a large beaker at 40 °C to obtain mixed solution B. The pH of mixed solution B was accurately controlled to be 7-8 during the dropwise addition. Mixed solution B was stirred at 90 °C for 3 hours to obtain a homogeneous mixed solution C. After cooling, mixed solution C was washed, centrifuged, and the solid D was collected. Solid D was calcined in air at 600 °C for 3 hours to obtain a high-entropy oxide.

[0056] Performance testing Test Example 1 Figure 1 Here are the XRD patterns of the high-entropy oxides obtained in the examples and comparative examples. Figure 2 Raman diagrams of the high-entropy oxides obtained in the examples and comparative examples; XRD and Raman spectroscopy results show that each embodiment mainly exhibits a typical cubic CeO2 fluorite structure. XRD patterns indicate that the catalyst prepared in this invention is a cubic CeO2 phase (PDF#43-1002). When 2θ (degrees) are 28.5, 33.1, 47.5, 56.3, 59.1, 69.4, and 79.1, the corresponding crystal planes are (111), (200), (220), (311), (222), (400), and (420).

[0057] Figure 2 Raman analysis results showed that: Comparative Example 1 at 470cm -1 The peak at 443 cm⁻¹ corresponds to the F₂g stretching vibration of the CeO₂ cubic fluorite structure, while elemental doping causes the peak at 443 cm⁻¹ in Examples 1-4 to be higher. -1 This characteristic peak was observed at 550~700cm. -1 The location is considered to be an oxygen vacancy in the CeO2 lattice. At 1123 cm⁻¹ -1 The detected signal value proves that Example 1 has more O2. - It can be used for the catalytic purification reaction of soot particles.

[0058] Test Example 2 The high-entropy oxides obtained in the examples and comparative examples were used in the catalytic oxidation (solid-solid) reaction of diesel engine exhaust soot. The test procedure was as follows: 90 mg of high-entropy oxides and 10 mg of soot were mixed thoroughly with a spatula for 2 minutes to obtain the test sample. The sample was then placed in a reaction tube and pretreated with N2 at 160°C for 4 minutes at a flow rate of 50 mL / min. The gas flow was then changed to a 300 mL / min mixture of 1000 ppm NO - 10 vol.% O2 - 7% steam-N2 balance, and the sample temperature was raised to 700°C. The CO / CO2 and NO / NO2 concentrations at the reactor outlet were detected using a Fourier transform infrared spectroscopy (FTIR) instrument. The results are as follows: Figure 3 (a) and Figure 13 As shown in (a) and Table 1.

[0059] Table 1. Catalytic purification efficiency of high-entropy oxides in diesel vehicle exhaust soot from the examples.

[0060] Table 2. Catalytic purification efficiency of high-entropy oxides in diesel vehicle exhaust soot for comparative purposes

[0061] Convert the activity integral to Figure 3 (b) and Figure 13 (b) Statistically, the temperature at which the catalytic oxidation of soot begins (T) 10% ), the temperature at which catalytic soot is rapidly oxidized (T) 50% The temperature at which the catalytic conversion of soot reaches 90% (T) 90% )At Figure 4 The soot used in the activity test of this invention was collected from marine diesel engine exhaust outlet soot. The hydrocarbons adsorbed by the marine soot can be combusted into CO2 at relatively low temperatures, thus affecting the To of the activity test results. 10% The impact is significant. Therefore, this invention uses T... 50% Evaluate the catalytic performance of the catalyst. Figure 4 All samples were processed according to T 50% Sort by Figure 4 It is evident that Example 1 exhibits the best activity, T 10% The temperature was 293℃, T 50% The temperature was 342℃, T 90% The temperature is 375℃, and the proportion of transition metal elements is 33.3%.

[0062] Test Example 3 To explore the elemental distribution of high-entropy oxides, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS) were used to collect data such as... Figure 5 The diagram shown. Figure 5(a), (b), (c), and (d) correspond to Examples 1, 2, 3, and 4, respectively. Figure 5 (a1-a6) correspond to the EDS signals of Ce, Zr, Pr, Ti, and Mn elements in Example 1, respectively. Figure 5 (b1-b6) correspond to the EDS signals of Ce, Zr, Pr, Cu, and Mn elements in Example 2, respectively. Figure 5 (c1-c6) correspond to the EDS signals of Ce, Zr, Pr, La, and Mn elements in Example 3, respectively. Figure 5 (d1-d6) correspond to the EDS signals of Ce, Zr, Pr, Cu, and La elements in Example 4, respectively. Figure 5 It can be seen that the elements in the tested sample are evenly distributed on particles at the micron level.

[0063] The morphology and structure of the high-entropy oxides in Examples 1-4 were observed using an electron scanning microscope, such as... Figure 6 As shown, Examples 2 and 4 each contain spherical particles ranging in size from hundreds of nanometers to several micrometers, formed by the stacking of nanoparticles, with the spherical particles in Example 4 being smaller than those in Example 2. Examples 1, 2, and 3 exhibit a mixed structure of irregular sheet-like and spherical structures. Comparative Example 1 was observed using a scanning electron microscope, as shown... Figure 8 As shown, Comparative Example 1 consists mainly of tightly packed particle aggregates at the micrometer scale. Upon further magnification, Comparative Example 1 still exhibits a similar particle aggregate morphology, and also contains a small amount of porous structure.

[0064] Figure 7 These are transmission electron microscopy (TEM) images of the high-entropy oxides. As can be seen from (a), (c), (e), and (g), the nanostructures of Examples 1-4 are all formed by the stacking of nanocrystals with non-uniform particle sizes. Comparative Example 1 was observed using a transmission electron microscope, as shown... Figure 9 As shown, it can be clearly seen that the structure of Comparative Example 1 is composed of nanocrystals, but its degree of nanocrystal aggregation is significantly higher than that of the embodiments.

[0065] Test Example 4 Figure 8 The diagram shows the H2 temperature programmed reduction (H2-TPR) of high-entropy oxides (a), the O2 temperature programmed oxidation (O2-TPD) diagram (b), and the soot temperature programmed reduction (Soot-TPR) diagram (c).

[0066] The H2-TPR test procedure is as follows: 0.1g of high-entropy oxide is placed in a quartz reaction tube and activated at 450℃ for 1h under a N2 atmosphere of 40mL / min. After cooling to room temperature, the gas is switched to a 5.0 vol.% H2-N2 mixture (40mL / min), and the reaction temperature is raised from room temperature to 900℃. The hydrogen consumption is monitored online using a thermal conductivity detector.

[0067] The O2-TPD test procedure is as follows: 0.1 g of high-entropy oxide sample is placed in a quartz reaction tube and activated at 450 °C for 1 h in a N2 atmosphere at 40 mL / min. After cooling to 80 °C, the gas is switched to a 5.0 vol.% O2-N2 mixture (40 mL / min). The 5.0 vol.% O2-N2 mixture is adsorbed at 80 °C for 2 h until saturation. Then, the reaction temperature is raised to 900 °C in an ultrapure N2 atmosphere (40 mL / min), and the oxygen content is monitored online using a thermal conductivity detector.

[0068] The Soot-TPR test procedure is as follows: 90 mg of high-entropy oxide and 10 mg of ship soot are mixed evenly with a spatula for 2 min to prepare the test sample. The test sample is then placed in a reaction tube and pretreated with N2 at 120℃ for 1 h by passing it through at 40 mL / min. The sample temperature is then raised to 900℃, and the CO2 content is monitored online using a thermal conductivity detector.

[0069] like Figure 8 As shown in (a), the reduction peak in Comparative Example 1 near 300–500 °C can be attributed to the reduction of surface lattice oxygen, and the reduction peak near 500–700 °C can be attributed to the reduction of bulk lattice oxygen. However, all examples doped with transition metal oxides exhibit reduction peak areas much larger than those in Comparative Example 1. In Examples 2, 4, and 6, surface lattice oxygen was reduced before 250 °C, and bulk lattice oxygen was completely reduced before 400 °C. This may be because Cu doping makes the material extremely easy to reduce. Example 3, doped with Cu, exhibited reduction peaks of 100–500 °C (surface lattice oxygen) and 500–900 °C (bulk lattice oxygen), respectively. This result may be due to Ti doping increasing the reduction temperature. The fact that the reduction temperature of Example 1 (Mn and Ti doped) is higher than that of Example 3 (Mn doped) also verifies this conclusion.

[0070] Depend on Figure 8 As shown in (b), the signals below 200°C are attributed to the desorption of weakly chemisorbed oxygen, the signals between 200 and 400°C are attributed to vacant oxygen, the signals between 400 and 600°C are considered to be the release of surface lattice oxygen, and the signals above 600°C are generally considered to be the release of bulk lattice oxygen. It is evident that the vacant oxygen concentrations in Examples 2 and 3 are greater than those in Comparative Example 1, and the surface lattice oxygen concentrations in all examples are greater than those in Comparative Example 1.

[0071] O2-TPD and H2-TPR tests can investigate the oxygen release capacity and redox capacity of various materials. In fact, the redox capacity of the catalyst for soot particles is determined by soot-TPR testing, and the results are as follows... Figure 8As shown in (c), in an N2 atmosphere, soot is oxidized only by the catalyst components themselves. Example 1 started reacting after 350°C, a lower reaction temperature than Examples 2, 3, and 4. The soot-TPR reduction peak areas were, in descending order: Example 1 > Example 2 > Example 3 > Example 4, with integral reduction peak areas of SExample 1 = 3884, SExample 2 = 656, SExample 3 = 507, and SExample 4 = 337, respectively. The soot-TPR reduction peak area of ​​Example 1 was approximately 5.9 times that of Example 2, 7.6 times that of Example 3, and 11.5 times that of Example 4. Therefore, the active oxygen concentration suitable for soot catalytic oxidation in Example 1 is much higher than that in Examples 2, 3, and 4. This may be because the soot catalytic purification temperature and reaction window temperature of Example 1 are much lower than those of the other examples.

[0072] Figure 12 The test results for H2-TPR(a) and O2-TPD(b) of Examples 7-11 are shown. Figure 12 As shown in (a), Example 7 had the lowest hydrogen reduction temperature, with a signal detected starting at 100°C, followed by Examples 8 and 9. Example 10 did not detect a signal until after 350°C. Figure 12 In (b), the top three vacancy oxygen concentrations are Example 10, Example 7, and Example 8, respectively. As can be seen from the desorbed surface lattice oxygen, Example 9 has the highest surface lattice oxygen concentration, followed by Example 7 and Example 8.

[0073] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A cerium-based high-entropy oxide, characterized in that, The cerium-based high-entropy oxide has a chemical composition of CeZrPrARO x wherein A and R are independently Nd, La, Y, Cu, Zn, Mn, Al, Ti or Fe, and A and R are different. The molar ratio of the Ce, Zr, Pr, A and R is 1-5:1-5:1-4:1-4:1-4; The value range of the x is 1.5-2.

2. The cerium-based high-entropy oxide of claim 1, wherein, The A and R are Nd and La, Cu and La, Zn and La, Mn and La, Fe and La, Al and La, Cu and Y, Ti and Y, Mn and Y, Mn and Ti, Cu and Mn or Cu and Ti.

3. The method of claim 1 or 2, wherein the cerium-based high-entropy oxide is prepared by the steps of: Comprising the following steps: Mixing the compound corresponding to the metal element in the cerium-based high-entropy oxide and water to obtain a metal source solution; Roasting the metal source solution to obtain the cerium-based high-entropy oxide.

4. The production method according to claim 3, characterized by, The compound corresponding to the Ce includes at least one of cerium nitrate, cerium acetate, cerium carbonate, cerium ammonium nitrate, cerium ammonium acetate and cerium ammonium carbonate; The compound corresponding to the Zr includes at least one of zirconium nitrate, zirconium acetate, zirconium oxynitrate, zirconium carbonate, zirconium ammonium carbonate and zirconium potassium carbonate; The compound corresponding to the Pr includes at least one of praseodymium nitrate, praseodymium hydroxide, praseodymium acetate, praseodymium chloride, praseodymium iodide, praseodymium acetate, praseodymium sulfate, praseodymium perchlorate, praseodymium phosphate, praseodymium oxalate and praseodymium carbonate; The compound corresponding to the Nd includes at least one of neodymium nitrate, neodymium hydroxide, neodymium acetate, neodymium chloride, neodymium iodide, neodymium acetate, neodymium sulfate, neodymium perchlorate, neodymium phosphate, neodymium oxalate and neodymium carbonate; The compound corresponding to the La includes at least one of lanthanum nitrate, lanthanum hydroxide, lanthanum acetate, lanthanum chloride, lanthanum iodide, lanthanum acetate, lanthanum sulfate, lanthanum perchlorate, lanthanum phosphate, lanthanum oxalate and lanthanum carbonate; The compound corresponding to the Y includes at least one of yttrium nitrate, yttrium hydroxide, yttrium acetate, yttrium chloride, yttrium iodide, yttrium acetate, yttrium sulfate, yttrium perchlorate, yttrium phosphate, yttrium oxalate and yttrium carbonate; The compound corresponding to the Cu includes at least one of copper nitrate, copper hydroxide, copper acetate, copper chloride, copper iodide, copper acetate, copper sulfate, copper perchlorate, copper phosphate, copper oxalate and copper carbonate; The compound corresponding to the Zn includes at least one of zinc nitrate, zinc hydroxide, zinc acetate, zinc chloride, zinc acetate, zinc propionate, zinc butyrate, zinc succinate, zinc sulfate, zinc perchlorate, zinc phosphate, zinc oxalate and zinc carbonate; The compound corresponding to the Mn includes at least one of manganese nitrate, manganese hydroxide, manganese acetate, manganese chloride, manganese acetate, manganese propionate, manganese butyrate, manganese succinate, manganese sulfate, manganese perchlorate, manganese phosphate, manganese oxalate and manganese carbonate; The compound corresponding to the Al includes at least one of aluminum nitrate, aluminum hydroxide, aluminum acetate, aluminum chloride, aluminum acetate, aluminum propionate, aluminum butyrate, aluminum succinate, aluminum sulfate, aluminum perchlorate, aluminum phosphate, aluminum oxalate and aluminum carbonate; The compound corresponding to the Ti includes at least one of titanium sulfate, titanium oxysulfate, tetrabutyl titanate, isopropyl titanate, fluorotitanate, metatitanate and titanate; The compound corresponding to the Fe includes at least one of iron nitrate, iron hydroxide, iron acetate, iron chloride, iron acetate, iron propionate, iron butyrate, iron succinate, iron sulfate, iron perchlorate, iron phosphate, iron oxalate and iron carbonate.

5. The preparation method according to claim 4, characterized in that, When the corresponding compound is difficult to dissolve in water, the compound is added in the form of a solution, and the solution is prepared by dissolving the compound difficult to dissolve in water in an acidic solution with a mass concentration of 10-30%.

6. The preparation method according to claim 3, characterized in that, The total molar concentration of metal ions in the metal source solution is 0.01-5 mol / L.

7. The preparation method according to claim 3, characterized in that, The calcination temperature is 200-800 DEG C, and the holding time is 0.5-8 h.

8. The production method according to claim 3 or 7, characterized by, The calcination is carried out in an air atmosphere.

9. The cerium-based high-entropy oxide of claim 1 or 2 or prepared by the method of any one of claims 3-8 as a catalyst in catalyzing a redox reaction.

10. Use according to claim 9, characterized in that, The catalytic redox reaction includes catalytic purification of particulate matters in exhaust gas of an internal combustion engine.

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