CN114604888B - Method for preparing rod-like, cube-like and polyhedral cerium oxide - Google Patents

Abstract

The present invention relates toA method for preparing cerium oxide with different appearances. In particular to a method for preparing rod-shaped, cube-shaped and polyhedral cerium oxide by a polyol solvothermal crystallization method. The method has the advantages of avoiding the use of strong alkali precipitant, simple catalyst preparation process, and no strong alkali metal ion (such as Na ⁺ And K ⁺ ) The product yield is high.

Description

Method for preparing rod-like, cube-like and polyhedral cerium oxide

Technical Field

The invention relates to a synthesis method of cerium oxide, in particular to a preparation method of rod-shaped, cubic and polyhedral cerium oxide.

Background

Cerium is the second element of the lanthanide series, the 25 th most abundant element on earth, and its reserves are as abundant as copper. Cerium oxide is widely used in the fields of ceramics (electronic ceramics, etc.), catalysis (catalysts, catalyst carriers, assistants), medicine (nano-enzymes, ultraviolet absorbers), polishing (polishing powder, polishing liquid, etc.), solid oxide fuel cells (fuel cell electrolytes), etc. due to its unique physicochemical properties.

Cerium oxide is a face-centered cubic fluorite structure, and cerium oxide particles are usually crystallized in the form of polyhedrons, mainly concentrated on the low-energy surface of the (111) family, followed by (110) and (100). By adjusting the pressure, temperature, pH, solvent, concentration, characteristics of the precursor and the additive, etc., the production rate of the crystal in different directions can be changed, thereby forming cerium oxide with different morphologies.

Cerium oxide with different morphologies is reported at present to be mainly: spherical, cubic, polyhedral, etc. having a zero-dimensional structure of similar dimensions in all directions; linear, rod-like, beam-like, etc. having a one-dimensional structure of similar dimensions in a certain direction; two-dimensional structures having similar dimensions in the partial direction are disk-like, sheet-like, etc.; other complex multi-level structures include mesoporous structures, core-shell structures, chrysanthemum-like structures, shuttle-like structures, and the like.

There are many methods for preparing cerium oxide, including precipitation, thermal decomposition, hydrothermal or solvothermal methods, sol-gel methods, electrochemical synthesis methods, template methods, milling methods, molten salt methods, and the like.

The precipitation method has simple process, the soluble precursor salt solution of cerium and the solution of the precipitant are mixed, the precipitate is obtained under certain conditions, and the cerium oxide material is obtained after solid-liquid separation, washing, drying and roasting of the precipitate. The method is favorable for industrialization, but the particle size is larger. For example Zhou Xinmu [ Zhou Xinmu, wang Aiqin, li Jing ] and the like, the research on the preparation of ultrafine polishing powder by high-density rare earth carbonate, rare earth, 2015,36 (5): 25-29 ], and the like, adding an ammonium bicarbonate precipitant into a cerium chloride solution to obtain high-density basic cerium carbonate with the particle size of about 200-300nm, and preparing cerium oxide by high-temperature treatment. The thermal decomposition method is to directly decompose the cerium precursor salt into cerium oxide at high temperature, and the method is simple and controllable, can realize industrial production, but is easy to generate ion agglomeration at high temperature and has larger particle size. For example Li Yongxiu [ Li Yongxiu, cheng Changming, chen Weifan, etc. ] hydrated cerium acetate is directly thermally decomposed to prepare ultrafine cerium oxide and its polishing performance. Inorganic chemistry report, 2006,22 (4): 733-737 ], et al prepare spherical nanoparticle-like agglomerate cerium oxide with good dispersibility and particle size in the range of 0.4-0.7 μm by calcining hydrated cerium acetate at high temperature. The template method uses some substances with regular shapes and structures as templates, and can prepare products with unique structures and high uniform sizes, but the templates are difficult to remove in some cases, so that the application of subsequent products is affected. Zhao Guozheng (Zhao Guozheng, li Changbo, mianchang, etc.) preparation of porous nano cerium oxide with starch as template and its catalytic performance research, environmental science research 2018,32 (1), 52-57, et al, under mild conditions, use cerium nitrate as cerium source and starch as template agent to prepare porous sponge cerium oxide. Cerium oxide materials prepared by the grinding method and the molten salt method are relatively poor in uniformity.

The hydrothermal or solvothermal preparation of cerium oxide is to pour the reaction liquid into a specially-made high-pressure reaction kettle and carry out crystallization treatment under certain conditions (temperature, pressure and the like). The reaction system is in subcritical or supercritical state, the physical and chemical properties of the solvent and the solute are greatly changed, and metastable substances with novel forms are easy to generate, so that the generation of materials with novel forms is facilitated. The hydrothermal/solvothermal method has a plurality of influencing factors, and precursor salts, solvent types, additives, temperature, pressure, time and the like have important influences on the final product form and size. Therefore, the precise control of the parameters is key to synthesizing cerium oxide with specific morphology, and is also the core of the technology.

Disclosure of Invention

The invention aims to provide a method for synthesizing rod-shaped, cube-shaped and polyhedral cerium oxide, which realizes the synthesis of the rod-shaped, cube-shaped and polyhedral cerium oxide by controlling the precipitation and crystallization processes and the adjustment of the types of polyalcohol and the control of the conditions. The method is simple and easy to operate, the polyol is environment-friendly, and the materials used in the process are safe.

The technical proposal is as follows:

mixing cerium soluble precursor salt solution and precipitant solution in certain proportion at certain temperature, filtering and washing the precipitate, re-dispersing in dihydric alcohol or polyhydric alcohol (with carbon number not less than 3) or polyhydric alcohol solution, crystallizing at certain temperature for some time, filtering, washing and drying the sample mixture to obtain rod-like, cube-like and polyhedral cerium oxide.

The soluble salt of cerium includes: one or more than two of cerium nitrate, cerium chloride, cerium sulfate, ammonium cerium nitrate, cerium acetate, cerium acetylacetonate and cerium oxalate;

the precipitant is one or more of urea, ammonium bicarbonate, ammonium carbonate and ammonia water;

the solvents for dissolving the cerium precursor salt and the precipitant are: water, ethanol or any ratio of its solution to water;

the molar ratio of Ce to the precipitant in the cerium precursor salt is 1/10-1/30;

the temperature of the solution at the time of precipitation was 20-90 ℃.

The dihydric alcohol comprises: a C2-C6 glycol or a mixed solution or a mixed aqueous solution thereof;

the polyol comprises: an aqueous solution of a polyol having a carbon number of 3 or more at room temperature and being solid, or a mixed solution of the above alcohols;

the mass fraction of water in the aqueous solution of the room temperature liquid alcohol is 5-95%;

the solvent before crystallization accounts for 50-95% of the total mass;

the crystallization temperature is 120-240 ℃; the crystallization time is 6-72h.

A scheme is provided:

the dihydric alcohol comprises: ethylene glycol, propylene glycol, butylene glycol;

the polyol comprises: glycerol or an aqueous solution thereof, erythritol, pentaerythritol, xylitol, glucose, sorbitol (wherein the mass fraction of alcohols is 5% -50%);

a scheme is provided:

the molar ratio of Ce to the precipitant in the cerium precursor salt is 1/20-1/30;

the crystallization temperature is 150-220 ℃; the crystallization time is 12-48h.

A scheme is provided:

the crystallization temperature is 170-220 ℃; the crystallization time is 24-48h.

The method has the advantages of avoiding the use of strong alkali precipitant, simple catalyst preparation process, and no strong alkali metal ion (such as Na ⁺ And K ⁺ ) The product yield is high.

The beneficial technical effects are as follows:

1. the raw materials used in the invention are cheap and easy to obtain, are green, safe and environment-friendly, the preparation process is controllable and easy to operate, and the control preparation of the rod-shaped, cubic and polyhedral cerium oxide can be realized;

2. the method avoids the use of strong alkali precipitants such as NaOH and KOH, and does not contain strong alkali metal ion (such as Na ⁺ 、K ⁺ Etc.), the purity of the product is high, the water consumption in the washing process is low, and the energy consumption is low.

Drawings

FIG. 1 is an electron micrograph of the product of examples 1, 8, 9.

Detailed Description

For further detailed description of the present invention, several specific embodiments are given below, but the present invention is not limited to these embodiments.

Example 1

Respectively dissolving cerium nitrate and precipitator urea in an aqueous solution, wherein the molar ratio of Ce to the precipitator is 1/30, dropwise adding the cerium nitrate solution into the urea solution under the stirring condition at 90 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent glycol aqueous solution (the crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the crystallization solvent glycol aqueous solution is 50%), crystallizing at 170 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 2

Respectively dissolving cerium nitrate and precipitator urea in an aqueous solution, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding the cerium nitrate solution into the urea solution under the stirring condition at 90 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent glycol aqueous solution (the crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the crystallization solvent glycol aqueous solution is 50%), crystallizing at 170 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 3

Respectively dissolving cerium nitrate and precipitator urea in an aqueous solution, wherein the molar ratio of Ce to the precipitator is 1/10, dropwise adding the cerium nitrate solution into the urea solution under the stirring condition at 90 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent glycol aqueous solution (the crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the crystallization solvent glycol aqueous solution is 50%), crystallizing at 170 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 4

Respectively dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water (the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycol (the crystallization solvent accounts for 70% of the total mass), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 5

Respectively dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water (the volume fraction of water is 50%), wherein the mole ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate, uniformly mixing the colloidal precipitate and crystallization solvent butanediol (the crystallization solvent accounts for 70% of the total mass), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 6

Respectively dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water (the volume fraction of water is 50%), wherein the mole ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol (the crystallization solvent accounts for 70% of the total mass), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 7

Dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water respectively (wherein the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent glycerol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 5%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 8

Dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water respectively (wherein the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent glycerol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 9

Dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water respectively (wherein the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent glycerol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 95%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 10

Dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water respectively (wherein the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent erythritol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the mass fraction of alcohols in the erythritol aqueous solution is 5%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 11

Respectively dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water (the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent xylitol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the mass fraction of alcohols in the xylitol aqueous solution is 25%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 12

Respectively dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water (the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent pentaerythritol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the mass fraction of alcohols in the pentaerythritol aqueous solution is 25%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 13

Respectively dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water (the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent xylitol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the mass fraction of alcohols in the xylitol aqueous solution is 50%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 14

Dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water respectively (wherein the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent glucose aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the mass fraction of alcohols in the glucose aqueous solution is 50%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 15

Respectively dissolving cerium chloride and precipitant ammonium bicarbonate in a mixed solution of ethanol and water (the volume fraction of water is 50%), wherein the molar ratio of Ce to precipitant is 1/20, dropwise adding the cerium chloride solution into the ammonium bicarbonate solution under the stirring condition of 60 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with a crystallization solvent sorbitol aqueous solution (the crystallization solvent accounts for 70% of the total mass, and the mass fraction of alcohols in the sorbitol aqueous solution is 50%), crystallizing at 170 ℃ for 48h, and filtering, washing and drying the obtained precipitate to obtain a final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 16

Respectively dissolving cerium acetate and precipitator ammonia water in ethanol, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium acetate solution into the ammonia water solution under the stirring condition of 20 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol aqueous solution (crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), crystallizing at 200 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 17

Respectively dissolving cerium acetate and precipitator ammonia water in ethanol, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium acetate solution into the ammonia water solution under the stirring condition of 20 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol aqueous solution (the crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), and crystallizing at 220 ℃ for 24h, and obtaining the final product after filtering, washing and drying the obtained precipitate. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 18

Respectively dissolving cerium acetate and precipitator ammonia water in ethanol, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium acetate solution into the ammonia water solution under the stirring condition of 20 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol aqueous solution (the crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), crystallizing at 240 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 19

Respectively dissolving cerium acetate and precipitator ammonia water in ethanol, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium acetate solution into the ammonia water solution under the stirring condition of 20 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol aqueous solution (crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), crystallizing at 150 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 20

Respectively dissolving cerium acetate and precipitator ammonia water in ethanol, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium acetate solution into the ammonia water solution under the stirring condition of 20 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol aqueous solution (the crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), crystallizing at 120 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 21

Dissolving cerium acetylacetonate and precipitator ammonia water in ethanol respectively, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium acetylacetonate solution into the ammonia water solution under the stirring condition of 20 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol aqueous solution (crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), crystallizing at 170 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 22

Respectively dissolving cerium oxalate and precipitator ammonia water in ethanol, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium oxalate solution into ammonia water solution under the stirring condition of 20 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycerol aqueous solution (crystallization solvent accounts for 80% of the total mass, and the volume fraction of water in the glycerol aqueous solution is 50%), crystallizing at 170 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 23

Respectively dissolving ceric ammonium nitrate and precipitator ammonium carbonate in water, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding the ceric ammonium nitrate solution into the ammonium carbonate solution under the stirring condition of 50 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycol aqueous solution (the crystallization solvent accounts for 95% of the total mass, and the volume fraction of water in the glycol aqueous solution is 50%), crystallizing at 170 ℃ for 6h, and obtaining the final product after filtering, washing and drying the obtained precipitate. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 24

Respectively dissolving ceric ammonium nitrate and precipitator ammonium carbonate in water, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding the ceric ammonium nitrate solution into the ammonium carbonate solution under the stirring condition of 50 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycol aqueous solution (the crystallization solvent accounts for 95% of the total mass, and the volume fraction of water in the glycol aqueous solution is 50%), crystallizing at 170 ℃ for 12h, and obtaining the final product after filtering, washing and drying the obtained precipitate. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 25

Respectively dissolving ceric ammonium nitrate and precipitator ammonium carbonate in water, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding the ceric ammonium nitrate solution into the ammonium carbonate solution under the stirring condition of 50 ℃, stirring for 30min, filtering, washing, separating out colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycol aqueous solution (the crystallization solvent accounts for 95% of the total mass, and the volume fraction of water in the glycol aqueous solution is 50%), crystallizing at 170 ℃ for 24h, and obtaining the final product after filtering, washing and drying the obtained precipitate. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

Example 26

Respectively dissolving cerium sulfate and precipitator ammonium carbonate in water, wherein the molar ratio of Ce to the precipitator is 1/20, dropwise adding cerium sulfate solution into ammonium carbonate solution under the stirring condition of 50 ℃, stirring for 30min, filtering, washing, separating colloidal precipitate from the mixture, uniformly mixing the colloidal precipitate with crystallization solvent glycol aqueous solution (the crystallization solvent accounts for 95% of the total mass, and the volume fraction of water in the glycol aqueous solution is 50%), crystallizing at 170 ℃ for 24h, and filtering, washing and drying the obtained precipitate to obtain the final product. The product yield, morphology, average particle size and specific surface area are shown in Table 1.

TABLE 1

Claims (5)

1. A method for synthesizing rod-shaped, cubic and polyhedral cerium oxide, which is characterized in that:

mixing a cerium soluble precursor salt solution with a precipitant solution, filtering and washing the obtained precipitate, re-dispersing the precipitate in one or more than two of dihydric alcohol or polyhydric alcohol solutions with carbon number more than or equal to 3, crystallizing, filtering, washing and drying the sample mixture to obtain one or more than two of rod-shaped, cubic and polyhedral cerium oxides;

the molar ratio of Ce to the precipitant in the cerium precursor salt is 1/10-1/30; the temperature of the solution is 20-90 ℃ during precipitation;

the dihydric alcohol comprises: one or more of ethylene glycol, propylene glycol and butanediol;

the polyol comprises: one or more of glycerol or its water solution, erythritol, pentaerythritol, xylitol, glucose, and sorbitol water solution; the mass fraction of alcohols in the aqueous solution of sorbitol is 5% -50%;

the crystallization temperature is 120-240 ℃; the crystallization time is 6-72h.

2. A method according to claim 1, characterized in that:

the soluble precursor salt of cerium includes: one or more than two of cerium nitrate, cerium chloride, cerium sulfate, ammonium cerium nitrate, cerium acetate, cerium acetylacetonate and cerium oxalate;

the precipitant is one or more of urea, ammonium bicarbonate, ammonium carbonate and ammonia water;

the solvents for dissolving the cerium precursor salt and the precipitant are: water, ethanol or any ratio of ethanol to water.

3. A method according to claim 1 or 2, characterized in that:

the molar ratio of Ce to precipitant in the cerium precursor salt is 1/20-1/30.

4. A method according to claim 1, characterized in that:

the crystallization temperature is 150-220 ℃; the crystallization time is 12-48h.

5. A method according to claim 1, characterized in that:

the crystallization temperature is 170-220 ℃; the crystallization time is 24-48 and h.

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