Rare earth doped cerium oxide spherical nano composite material as well as preparation method and application thereof

Abstract

The invention relates to a rare earth doped cerium oxide spherical nano composite material as well as a preparation method and application thereof, the preparation method comprises the following steps: mixing a cerium source, a non-cerium rare earth source and a saccharide chelating agent, and sequentially stirring, drying and calcining to obtain the rare earth doped cerium oxide spherical nano composite material, the saccharide chelating agent comprises cane sugar. The carbohydrate chelating agent is adopted, the carbohydrate chelating agent is limited to comprise cane sugar, the dispersity of the cerium source and the non-cerium rare earth source can be improved through hydroxyl of the carbohydrate chelating agent, and the growth speed of crystal grains can be controlled. Furthermore, a cerium source and a non-cerium rare earth source are complexed in a cross-linked structure of a saccharide complexing agent by utilizing a special molecular structure of the saccharide complexing agent, so that the rare earth doped cerium oxide spherical nano composite material which is small in particle size, uniform in morphology and high in specific surface area can be obtained under a calcining condition. The preparation method provided by the invention is green, simple, efficient and low in cost.

Description

Technical Field

[0001] The invention relates to the technical field of solid oxide fuel cells, and in particular to a spherical cerium oxide nanocomposite material, and in particular to a rare earth-doped spherical cerium oxide nanocomposite material, and a preparation method and application thereof. Background Art

[0002] For many years, developing clean and efficient energy technology has been the goal of scholars at home and abroad. A fuel cell is an electrochemical conversion device that converts chemical energy in a fuel into electrical energy. Fuel cells usually involve an electrochemical reaction between hydrogen (fuel) and oxygen, and the product contains only water, which can achieve clean power generation. There is no combustion of fuel in the power generation process, and it is not limited by the Carnot cycle. The energy conversion efficiency can reach more than 40%.

[0003] As a type of fuel cell, solid oxide fuel cells (SOFCs) usually operate at medium-high temperatures of 600°C-1000°C. The higher operating temperature increases the catalytic reaction rate and ion migration rate of the fuel cell, making it unnecessary to use expensive precious metal electrodes. SOFCs' all-solid-state structure and unique operating temperature give them a higher energy conversion efficiency (more than 60%), and the combined heat and power efficiency can reach more than 90%, with significant environmental and economic benefits.

[0004] Solid oxide fuel cells are usually composed of components such as anodes, electrolytes, cathodes and connectors. The electrolyte is usually composed of a ceramic film, which serves to isolate the fuel gas (anode side) from oxygen (cathode side) and conduct oxygen ions. Available electrolyte materials for SOFC include stabilized zirconia or doped cerium oxide, and the conductivity of doped cerium oxide is significantly better than that of stabilized zirconia. Although cerium oxide itself has a low conductivity, doping with trivalent rare earth ions (such as gadolinium, samarium, and yttrium) can achieve an exponential increase in conductivity by increasing the concentration of oxygen vacancies.

[0005] Common preparation methods for rare earth doped cerium oxide powders include high energy ball milling, coprecipitation, hydrothermal, combustion and sol-gel methods. CN102583495A discloses the use of a hydrothermal method to synthesize rare earth metal ion doped cerium oxide nanomaterials with good crystallinity and uniform size, but it requires the use of a hydrothermal kettle under high temperature and high pressure for 12 hours to 30 hours, which prolongs the production time and increases the production cost. CN115579499A discloses a method for preparing rare earth oxide doped cerium oxide ceramic powders without high temperature and high pressure, but the toxic solvents and complexing agents used cause environmental concerns. That is, in the currently disclosed technology, it is difficult to avoid the problems of long preparation time, complicated process or the use of toxic reagents.

[0006] Therefore, developing a green, simple, efficient and low-cost method for preparing rare earth-doped cerium oxide spherical nanocomposites has become an urgent problem to be solved. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a rare earth doped cerium oxide spherical nanocomposite material and its preparation method and application. The present invention adopts a carbohydrate chelating agent, and limits the carbohydrate chelating agent to include sucrose, which has hydroxyl groups that can not only improve the dispersibility of the cerium source and the non-cerium rare earth source, but also control the growth rate of the grains. Furthermore, by utilizing the special molecular structure of the carbohydrate complexing agent, the cerium source and the non-cerium rare earth source are complexed in the cross-linked structure of the carbohydrate complexing agent, which is conducive to obtaining a rare earth doped cerium oxide spherical nanocomposite material with small particle size, uniform morphology and high specific surface area under calcination conditions. The preparation method provided by the present invention is green, simple, efficient and low-cost.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing a rare earth-doped cerium oxide spherical nanocomposite material, the preparation method comprising the following steps: mixing a cerium source, a non-cerium rare earth source and a carbohydrate chelating agent, and then stirring, drying and calcining in sequence to obtain the rare earth-doped cerium oxide spherical nanocomposite material; the carbohydrate chelating agent comprises sucrose.

[0010] The present invention adopts a sugar chelating agent, and limits the sugar chelating agent to include sucrose, the hydroxyl group of which can not only improve the dispersibility of the cerium source and the non-cerium rare earth source, but also control the growth rate of the grains. Furthermore, by utilizing the special molecular structure of the sugar complexing agent, the cerium source and the non-cerium rare earth source are complexed in the cross-linked structure of the sugar complexing agent, which is conducive to obtaining a rare earth-doped cerium oxide spherical nanocomposite material with small particle size, uniform morphology and high specific surface area under calcination conditions. The preparation method provided by the present invention is green, simple, efficient and low-cost.

[0011] Preferably, the cerium source comprises cerium acetate.

[0012] Preferably, the non-cerium rare earth source includes any one of a lanthanum source, a praseodymium source, a neodymium source, a samarium source, a dysprosium source, an erbium source, a ytterbium source, a lutetium source, a scandium source or a yttrium source, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of a lanthanum source and a praseodymium source, a combination of a neodymium source and a samarium source, or a combination of a dysprosium source, an erbium source and a ytterbium source.

[0013] Preferably, the non-cerium rare earth source comprises a non-cerium rare earth acetate.

[0014] The present invention uses cerium acetate as a cerium source and non-cerium rare earth acetate as a non-cerium rare earth source. Acetate will be converted into carbon dioxide and water vapor in the subsequent reaction, and will not cause pollution to the environment. That is, the present invention has achieved the requirement of green and pollution-free from the raw material level.

[0015] Preferably, the molar ratio of the cerium source and the non-cerium rare earth source is (4-9):1, for example, it can be 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] The present invention can further control the doping ratio of rare earth doped cerium oxide nanocomposite powder by regulating the molar ratio of cerium source and non-cerium rare earth source. If the doping ratio of non-cerium rare earth element is too high, defect association will be caused, and the electrochemical performance will be reduced; if the doping ratio of non-cerium rare earth element is too low, sufficient oxygen vacancies cannot be generated, and it is difficult to achieve a significant improvement in electrochemical performance. Within the preferred range of the molar ratio of cerium source and non-cerium rare earth source, the electrochemical performance of rare earth doped cerium oxide nanocomposite powder can be further improved.

[0017] Preferably, the mixing includes a first mixing and a second mixing.

[0018] Preferably, the first mixing method comprises mixing a cerium source and a non-cerium rare earth source to obtain a mixed salt solution.

[0019] Preferably, the second mixing method comprises adding the saccharide chelating agent powder directly into the mixed salt solution.

[0020] Preferably, the second mixing method further comprises dissolving the saccharide chelating agent powder in deionized water to form a viscous solution, and then adding the solution dropwise to the mixed salt solution.

[0021] Preferably, the metal ion concentration of the mixed salt solution is 0.01mol / L-5mol / L, for example, it can be 0.01mol / L, 1mol / L, 2mol / L, 3mol / L, 4mol / L or 5mol / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 0.1mol / L-1mol / L.

[0022] Preferably, the carbohydrate chelating agent comprises a mixture of dextran and sucrose.

[0023] Preferably, the mass ratio of dextran to sucrose is 1:(0.1-20), for example, it can be 1:0.1, 1:5, 1:10, 1:15, 1:18 or 1:20, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 1:(5-20).

[0024] The present invention uses a carbohydrate chelating agent, and the carbohydrate chelating agent is limited to sucrose, which has a hydroxyl group (-OH) that loses a proton in water to form an oxygen anion (-O - ), chelating positively charged metal cations in the solution. Since the hydroxyl groups are evenly distributed on the surface of the metal ions, the metal ions can be kept dispersed and prevented from agglomerating. In addition, the chelation of metal ions by the hydroxyl groups can control the crystal growth process, and a rare earth-doped cerium oxide spherical nanocomposite material with small particle size, uniform morphology and high specific surface area can be prepared.

[0025] Dextran can effectively chelate and disperse metal ions, while sucrose has higher environmental benefits and lower economic costs. When dextran and sucrose are added to a mixed salt solution at the same time, dextran stabilizes the structure of sucrose through cross-linking, and the addition of a small amount of dextran can give sucrose a high weight average molecular weight long chain structure similar to dextran, thereby reducing costs during the production process. In order to take into account both the chelation and complexation effect and the economic benefits, the present invention preferably uses a mixture of dextran and sucrose as a carbohydrate chelating agent.

[0026] Preferably, the number average molecular weight of the dextran is ≥2000, for example, it can be 2000, 5000, 10000, 30000, 50000, 100000 or 200000, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] The present invention further limits the weight average molecular weight of dextran to ensure the chain length of dextran, which can improve the chelating effect of dextran, improve metal dispersibility and prevent agglomeration on the one hand; on the other hand, it can ensure that the dextran stabilizes the sucrose structure during the subsequent calcination process and utilizes the surface energy to obtain a spherical rare earth-doped cerium oxide nanocomposite material.

[0028] Preferably, the mass addition amount of the carbohydrate chelating agent is M1, the sum of the mass addition amounts of the cerium source and the non-cerium rare earth source is M2, and the mass ratio of M1 to M2 is 1:(0.1-20), for example, it can be 1:0.1, 1:5, 1:10, 1:15, 1:18 or 1:20, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 1:(1-10).

[0029] The present invention can make the chelating agent play a better chelating and complexing effect by regulating the mass ratio of the mass of the saccharide chelating agent to the cerium source and the non-cerium rare earth source. When the mass addition amount of the chelating agent is too high, the difficulty of removing organic matter will increase. When the mass addition amount of the chelating agent is too low, it cannot play a good chelating effect and cannot ensure the uniform precipitation and dispersion of ions. Within the preferred range of the mass ratio of the mass of the saccharide chelating agent to the cerium source and the non-cerium rare earth source, the chelating and complexing effect of the saccharide chelating agent can be further improved.

[0030] Preferably, the stirring rate is 100r / min-1000r / min, for example, it can be 100r / min, 200r / min, 400r / min, 600r / min, 800r / min or 1000r / min, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 300r / min-600r / min.

[0031] Preferably, the stirring time is 0.5h-12h, for example, 0.5h, 2h, 4h, 6h, 8h, 10h or 12h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 1h-6h.

[0032] Preferably, heating is performed after stirring and before drying.

[0033] Preferably, the heating insulation temperature is 50℃-100℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 80℃-90℃.

[0034] In the present invention, heating is for the purpose of rapidly evaporating water and accelerating the chelation and complexation rate. Examples of heating methods include water bath heating, oil bath heating or electric heating plate heating.

[0035] Preferably, the drying insulation temperature is 20°C-250°C, for example, it can be 20°C, 50°C, 100°C, 150°C, 200°C or 250°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 70°C-120°C.

[0036] Preferably, the drying insulation time is 0.5-48h, for example, it can be 0.5h, 4h, 10h, 20h, 30h, 40h or 48h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 6-20h.

[0037] Preferably, a crushing process is performed after the drying and before the calcination.

[0038] Preferably, the calcination holding temperature is 350°C-1000°C, for example, it can be 350°C, 500°C, 600°C, 800°C, 900°C or 1000°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 600°C-900°C.

[0039] Preferably, the calcination holding time is 2h-24h, for example, 2h, 5h, 10h, 15h, 20h, 22h or 24h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 6h-12h.

[0040] Preferably, the calcining device is a muffle furnace or a tubular furnace.

[0041] Preferably, the ambient atmosphere of the tube furnace includes an oxygen atmosphere and / or an air atmosphere.

[0042] The present invention obtains a metal oxide composite powder with high crystallinity by calcination, and at the same time, the chelating agent is completely oxidized and pyrolyzed. The chelating agent can be completely pyrolyzed within the preferred range of the calcination end temperature and the holding time. The pyrolysis product of the chelating agent of the present invention is only CO 2 and water, without NO 2 or SO 2 In the process, green production can also be achieved by eliminating polluting gases such as chlorine dioxide. Furthermore, a spherical rare earth-doped cerium oxide nanocomposite material with uniform grain size can be obtained within the preferred range of calcination end temperature and holding time.

[0043] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0044] (1) A cerium source and a non-cerium rare earth source are mixed in proportion and dissolved in deionized water to obtain a mixed salt solution.

[0045] (2) Adding a carbohydrate chelating agent to the mixed salt solution in proportion, stirring and heating in sequence to obtain a gel-like white precursor material; the stirring rate is 100 r / min-1000 r / min, the stirring time is 0.5 h-12 h, and the heating insulation temperature is 50° C.-100° C.

[0046] (3) The gel-like white precursor material is dried and calcined in sequence to obtain the rare earth-doped cerium oxide spherical nanocomposite material, the drying insulation temperature is 20°C-250°C, the drying insulation time is 0.5-48h, the calcination insulation temperature is 350°C-1200°C, and the calcination insulation time is 2h-24h.

[0047] In the second aspect, the present invention provides a rare earth-doped cerium oxide spherical nanocomposite material prepared by the preparation method described in the first aspect, wherein the particle size D50 of the rare earth-doped cerium oxide spherical nanocomposite material is 10nm-50nm, for example, it can be 10nm, 15nm, 20nm, 30nm, 40nm, 45nm or 50nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] The rare earth doped cerium oxide spherical nano composite material prepared by the invention has small particle size, uniform morphology and high specific surface area, and has good sintering performance and electrochemical performance.

[0049] In a third aspect, the present invention provides a solid oxide fuel cell, wherein the raw material of the solid oxide fuel cell includes the rare earth-doped cerium oxide spherical nanocomposite material described in the second aspect.

[0050] The rare earth doped cerium oxide spherical nanocomposite material provided by the invention can be applied to anode materials, electrolytes or cathode materials in solid oxide fuel cells to improve the performance and life of the solid oxide fuel cells.

[0051] Compared with the prior art, the present invention has at least the following beneficial effects:

[0052] (1) The present invention uses a carbohydrate chelating agent, and the carbohydrate chelating agent includes sucrose, which has hydroxyl groups that can not only improve the dispersibility of the cerium source and the non-cerium rare earth source, but also control the growth rate of the grains. Sucrose has higher environmental benefits and lower economic costs.

[0053] (2) The present invention utilizes the special molecular structure of the carbohydrate complexing agent to complex the cerium source and the non-cerium rare earth source in the cross-linked structure of the carbohydrate complexing agent, which is conducive to obtaining a rare earth-doped cerium oxide spherical nanocomposite material with small particle size, uniform morphology and high specific surface area under calcination conditions.

[0054] (3) The preparation method provided by the present invention is green, simple, efficient and low-cost both in terms of raw materials and process. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a process flow chart for preparing rare earth-doped cerium oxide spherical nanocomposite materials according to the present invention;

[0056] Figure 2 is the XRD diagram of the rare earth-doped cerium oxide spherical nanocomposite material prepared in Example 1, Example 2 and Example 10 of the present invention;

[0057] Figure 3 is a SEM image of the rare earth-doped cerium oxide spherical nanocomposite material prepared in Example 1 of the present invention;

[0058] Figure 4a-4b is the EDS image of the ceramic sheet obtained by sintering Example 1 of the present invention, Figure 4c-4f This is an energy spectrum analysis diagram of Ce, Sm and O of the ceramic piece obtained by sintering Example 1 of the present invention. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0060] Example 1

[0061] This embodiment provides a method for preparing a rare earth-doped cerium oxide spherical nanocomposite material, the preparation method comprising the following steps:

[0062] (1) mixing hydrated cerium acetate and hydrated samarium acetate in a molar ratio of cerium ion to samarium ion of 9:1, dissolving the mixture in deionized water, and stirring at room temperature for 2 h to obtain a mixed salt solution with a total metal ion concentration of 0.1 mol / L;

[0063] (2) The mass addition amount of the carbohydrate chelating agent is M1, the sum of the mass addition amounts of the cerium source and the non-cerium rare earth source in step (1) is M2, the mass ratio of M1 to M2 is 1:4, the carbohydrate chelating agent is weighed; and the carbohydrate chelating agent is added to the mixed salt solution in step (1) for mixing and stirring to completely dissolve it, and then heating is started to evaporate the water to obtain a gel-like white precursor material; the carbohydrate chelating agent is a mixture of dextran and sucrose, the number average molecular weight of the dextran is 30,000, wherein the mass ratio of dextran to sucrose is 1:1, the mixing and stirring speed is 500 r / min, the mixing and stirring time is 6 h, and the heating insulation temperature is 80°C;

[0064] (3) drying, crushing and calcining the gel-like white precursor material in sequence to obtain the rare earth-doped cerium oxide spherical nanocomposite material; the drying insulation temperature is 100° C., the drying insulation time is 24 h, the crushing method is ball milling, the calcination insulation temperature is 600° C., and the calcination insulation time is 12 h;

[0065] The samarium-doped cerium oxide spherical nanocomposite material prepared in this embodiment has a chemical formula of Ce 0.9 Sm 0.1 O 1.95 ;

[0066] Figure 3 : is a SEM image of the rare earth doped cerium oxide spherical nanocomposite material prepared in Example 1 of the present invention. It can be seen from the image that the prepared rare earth doped cerium oxide spherical nanocomposite material has a uniform morphology and is spherical, and the particle size is about 30 nm;

[0067] Figure 4a-4b is the EDS image of the ceramic sheet obtained by sintering Example 1 of the present invention, Figure 4c-4fThis is an energy spectrum analysis diagram of Ce, Sm and O of the ceramic sheet sintered in Example 1 of the present invention. It can be seen from the figure that the sintered ceramic sheet has a high density and uniform element distribution.

[0068] Example 2

[0069] This embodiment provides a method for preparing a rare earth-doped cerium oxide spherical nanocomposite material, the preparation method comprising the following steps:

[0070] (1) mixing hydrated cerium acetate and samarium chloride in a molar ratio of cerium ion to samarium ion of 4:1, dissolving the mixture in deionized water, and stirring at room temperature for 4 h to obtain a mixed salt solution with a total metal ion concentration of 0.01 mol / L;

[0071] (2) The mass addition amount of the carbohydrate chelating agent is M1, the sum of the mass addition amounts of the cerium source and the non-cerium rare earth source in step (1) is M2, the mass ratio of M1 to M2 is 1:1, and the carbohydrate chelating agent is weighed; the carbohydrate chelating agent is dissolved in deionized water to obtain a viscous solution, and is added dropwise to the mixed salt solution in step (1), stirred to completely dissolve it, and then heated to evaporate the water to obtain a gel-like white precursor material; the carbohydrate chelating agent is a mixture of dextran and sucrose, the number average molecular weight of the dextran is 2000, wherein the mass ratio of dextran to sucrose is 1:10, the mixing and stirring speed is 100 r / min, the mixing and stirring time is 12 h, and the heating insulation temperature is 50°C;

[0072] (3) The gel-like white precursor material is dried, crushed and calcined in sequence to obtain the rare earth-doped cerium oxide spherical nanocomposite material; the drying insulation temperature is 250°C, the drying insulation time is 0.5h, the crushing method is grinding and crushing, the calcination insulation temperature is 900°C, and the calcination insulation time is 6h.

[0073] The samarium-doped cerium oxide spherical nanocomposite material prepared in this embodiment has a chemical formula of Ce 0.8 Sm 0.2 O 1.90 .

[0074] Example 3

[0075] This embodiment provides a method for preparing a rare earth-doped cerium oxide spherical nanocomposite material, the preparation method comprising the following steps:

[0076] (1) mixing hydrated cerium acetate and hydrated samarium acetate in a molar ratio of cerium ion to samarium ion of 9:1, dissolving the mixture in deionized water, and stirring at room temperature for 3 h to obtain a mixed salt solution with a total metal ion concentration of 5 mol / L;

[0077] (2) According to the mass addition amount of the saccharide chelating agent as M1, the sum of the mass addition amounts of the cerium source and the non-cerium rare earth source in step (1) as M2, and the mass ratio of M1 to M2 as 1:10, the saccharide chelating agent is weighed; and the saccharide chelating agent is added to the mixed salt solution in step (1) and stirred to completely dissolve it, and then heating is started to evaporate the water to obtain a gel-like white precursor material; the saccharide chelating agent is sucrose, the mixing and stirring speed is 1000r / min, the mixing and stirring time is 0.5h, and the heating end temperature is 100°C;

[0078] (3) The gel-like white precursor material is dried, crushed and calcined in sequence to obtain the rare earth-doped cerium oxide spherical nanocomposite material; the drying insulation temperature is 20°C, the drying insulation time is 48h, the crushing method is ball milling crushing, the calcination insulation temperature is 600°C, and the calcination insulation time is 12h.

[0079] The samarium-doped cerium oxide spherical nanocomposite material prepared in this embodiment has a chemical formula of Ce 0.9 Sm 0.1 O 1.95 .

[0080] Example 4

[0081] The only difference between this embodiment and embodiment 1 is that, except that the non-cerium rare earth source in step (1) is replaced by hydrated yttrium acetate instead of hydrated samarium acetate, the rest is the same as embodiment 1.

[0082] The samarium-doped cerium oxide spherical nanocomposite material prepared in this embodiment has a chemical formula of Ce 0.9 Y 0.1 O 1.95 .

[0083] Example 5

[0084] The difference between this embodiment and embodiment 1 is that, except that the non-cerium rare earth source in step (1) is replaced by hydrated samarium acetate with hydrated lanthanum acetate, the rest is the same as embodiment 1.

[0085] The samarium-doped cerium oxide spherical nanocomposite material prepared in this embodiment has a chemical formula of Ce 0.9 La 0.1 O 1.95 .

[0086] Example 6

[0087] The difference between this embodiment and embodiment 1 is that, except for the mass ratio of the carbohydrate chelating agent to the cerium source and the non-cerium rare earth source in step (2) being 1:0.1, the rest is the same as embodiment 1.

[0088] Example 7

[0089] The difference between this embodiment and embodiment 1 is that, except for the mass ratio of the carbohydrate chelating agent to the cerium source and the non-cerium rare earth source in step (2) being 1:20, the rest is the same as embodiment 1.

[0090] Example 8

[0091] The only difference between this embodiment and embodiment 1 is that, except that the carbohydrate chelating agent in step (2) is only sucrose, the rest is the same as embodiment 1.

[0092] Example 9

[0093] The only difference between this embodiment and embodiment 1 is that, except that the number average molecular weight of the dextran in step (2) is 1500, the rest is the same as embodiment 1.

[0094] Example 10

[0095] The only difference between this embodiment and embodiment 1 is that, except for the calcination temperature of step (3) being 350° C., the rest is the same as embodiment 1.

[0096] Figure 2 3 is the XRD diagram of the rare earth-doped cerium oxide spherical nanocomposite materials prepared in Example 1, Example 2 and Example 10 of the present invention. It can be seen from the diagram that the prepared rare earth-doped cerium oxide spherical nanocomposite materials all have a cubic fluorite structure, proving the formation of a doped solid solution.

[0097] Embodiment 11

[0098] The only difference between this embodiment and embodiment 1 is that, except for the calcination temperature of step (3) being 1000° C., the rest is the same as embodiment 1.

[0099] Example 12

[0100] The only difference between this embodiment and embodiment 1 is that, except that the holding time of calcination in step (3) is 2 hours, the rest is the same as embodiment 1.

[0101] Embodiment 13

[0102] The only difference between this embodiment and embodiment 1 is that, except for the holding time of calcination in step (3) being 24 hours, the rest is the same as embodiment 1.

[0103] Embodiment 14

[0104] The difference between this embodiment and embodiment 1 is that, except for the mass ratio of dextran to sucrose in step (2) being 1:0.1, the rest is the same as embodiment 1.

[0105] Embodiment 15

[0106] The only difference between this embodiment and embodiment 1 is that, except for the mass ratio of dextran to sucrose in step (2) being 1:20, the rest is the same as embodiment 1.

[0107] Comparative Example 1

[0108] The difference between this comparative example and Example 1 is that, except that the chelating agent in step (2) is acetylacetone, the rest is the same as Example 1.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 1 is that, except that the carbohydrate chelating agent in step (2) is only dextran, the rest is the same as Example 1.

[0111] Test Method

[0112] Average grain size: XRD and SEM were used to perform phase analysis and micromorphology analysis on the obtained rare earth doped cerium oxide nanocomposite powder, and the average grain size was calculated and recorded in Table 1;

[0113] Specific surface area: The specific surface area of ​​the rare earth-doped cerium oxide spherical nanocomposite material was measured by a physical adsorption instrument and recorded in Table 1;

[0114] Density of ceramic sheets: The rare earth-doped cerium oxide spherical nanocomposites obtained in Examples 1 to 14 and Comparative Examples 1 to 2 were cold isostatically pressed to obtain cylindrical ceramic green bodies; the temperature was then raised to 1400°C and sintered for 6 hours in a muffle furnace to obtain ceramic sheets with high density. The density of the ceramic sheets was measured by the Archimedean drainage method to characterize the sintering activity of the powders, and the data are recorded in Table 1.

[0115] Table 1

[0116]

[0117] The test results show that:

[0118] (1) It can be seen from Examples 1 to 15 and Comparative Examples 1 to 2 that the present invention uses a carbohydrate chelating agent, and limits the carbohydrate chelating agent to include sucrose, and adds it to a mixed salt solution. The hydroxyl groups it has can not only improve the dispersibility of the cerium source and the non-cerium rare earth source, but also control the growth rate of the grains. Furthermore, by utilizing the special molecular structure of the carbohydrate chelating agent, the cerium source and the non-cerium rare earth source are complexed in the cross-linked structure of the carbohydrate chelating agent, which is conducive to obtaining a rare earth-doped cerium oxide spherical nanocomposite material with small particle size, uniform morphology and high specific surface area under calcination conditions. The preparation method provided by the present invention is green, simple, efficient and low-cost, both in terms of raw material level and process level.

[0119] (2) It can be seen from Example 1 and Example 4-Example 5 that the difference in the rare earth ion radius of the present invention will cause changes in the lattice distortion and defect concentration of the doped cerium oxide, thereby affecting the high-temperature diffusion rate and resulting in differences in the average grain size.

[0120] (3) It can be seen from Examples 1 and 6-7 that the present invention further regulates the average grain size of cerium oxide by further limiting the amount of added saccharide chelating agent. When the amount of added saccharide chelating agent is high, a certain amount of organic matter will remain during the pyrolysis process, thereby affecting the grain growth. That is, the present invention further limits the amount of added saccharide chelating agent, and the average grain size of the prepared rare earth-doped cerium oxide spherical nanocomposite material is further reduced, and the specific surface area is further increased.

[0121] (4) It can be seen from Example 1, Example 8-Example 9 and Comparative Examples 1-Comparative Examples 2 that the rare earth-doped cerium oxide spherical nanocomposite material prepared by the present invention by regulating the type of carbohydrate chelating agent, wherein the carbohydrate chelating agent includes sucrose, and regulating the number average molecular weight of the dextran therein, has a further reduced average grain size and a further increased specific surface area.

[0122] (5) It can be seen from Examples 1 and 10 to 13 that the average grain size of the rare earth-doped cerium oxide spherical nanocomposite material prepared by further regulating the calcination end temperature and the holding time is further reduced.

[0123] (6) It can be seen from Example 1 and Example 14-Example 15 that the rare earth-doped cerium oxide spherical nanocomposite material prepared by further regulating the mass ratio of dextran and sucrose in the carbohydrate chelating agent in the present invention has a further reduced average grain size and a further increased specific surface area.

[0124] In summary, the present invention adopts a carbohydrate chelating agent, and limits the carbohydrate chelating agent to include sucrose, the hydroxyl group of which can not only improve the dispersibility of the cerium source and the non-cerium rare earth source, but also control the growth rate of the grains. Furthermore, by utilizing the special molecular structure of the carbohydrate complexing agent, the cerium source and the non-cerium rare earth source are complexed in the cross-linked structure of the carbohydrate complexing agent, which is conducive to obtaining a rare earth-doped cerium oxide spherical nanocomposite material with small particle size, uniform morphology and high specific surface area under calcination conditions. The preparation method provided by the present invention is green, simple, efficient and low-cost, both in terms of raw material level and process level.

[0125] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a rare earth-doped cerium oxide spherical nanocomposite material, characterized in that: The preparation method comprises the following steps: After mixing a cerium source, a non-cerium rare earth source and a saccharide chelating agent, stirring, drying and calcining are performed in sequence to obtain the rare earth-doped cerium oxide spherical nanocomposite material; The carbohydrate chelating agent includes sucrose.

2. The preparation method according to claim 1, characterized in that: The cerium source includes cerium acetate; Preferably, the non-cerium rare earth source includes any one of a lanthanum source, a praseodymium source, a neodymium source, a samarium source, a dysprosium source, an erbium source, a ytterbium source, a lutetium source, a scandium source or a yttrium source, or a combination of at least two thereof; Preferably, the non-cerium rare earth source comprises a non-cerium rare earth acetate.

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the cerium source and the non-cerium rare earth source is (4-9):1; Preferably, the mixing includes a first mixing and a second mixing; Preferably, the first mixing method comprises mixing a cerium source and a non-cerium rare earth source to obtain a mixed salt solution; Preferably, the metal ion concentration of the mixed salt solution is 0.01 mol / L-5 mol / L, preferably 0.1 mol / L-1 mol / L.

4. The preparation method according to any one of claims 1 to 3, characterized in that The carbohydrate chelating agent includes a mixture of dextran and sucrose; Preferably, the mass ratio of dextran to sucrose is 1:(0.1-20), preferably 1:(5-20); Preferably, the number average molecular weight of the dextran is ≥2000.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The mass addition amount of the saccharide chelating agent is M1, the sum of the mass addition amounts of the cerium source and the non-cerium rare earth source is M2, and the mass ratio of M1 to M2 is 1:(0.1-20), preferably 1:(1-10).

6. The preparation method according to any one of claims 1 to 5, characterized in that: The stirring rate is 100r / min-1000r / min, preferably 300r / min-600r / min; Preferably, the stirring time is 0.5h-12h, preferably 1h-6h.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The drying temperature is 20°C-250°C, preferably 70°C-120°C; Preferably, the drying heat preservation time is 0.5-48h, preferably 6-20h.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The calcination holding temperature is 350°C-1000°C, preferably 600°C-900°C; Preferably, the calcination holding time is 2h-24h, preferably 6h-12h.

9. A rare earth doped cerium oxide spherical nanocomposite material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The particle size D50 of the rare earth-doped cerium oxide spherical nanocomposite material is 10nm-50nm.

10. A solid oxide fuel cell, characterized in that: The raw material of the solid oxide fuel cell comprises the rare earth-doped cerium oxide spherical nanocomposite material as claimed in claim 9.

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