Micron-sized spherical cerium oxide and preparation method thereof

Abstract

The invention discloses micron-sized spherical cerium oxide and a preparation method thereof. The preparation method comprises the following steps: 1) mixing water-soluble cerium salt, polyethylene glycol with the molecular weight of 800-2000, C1-C3 alkyl alcohol and water to obtain a primary mixture; (2) putting the primary mixture into a reaction kettle, sealing, reacting at 160-210 DEG C, and separating to obtain a solid after the reaction is finished; 3) drying and roasting the solid to obtain micron-sized spherical cerium oxide; wherein the mass ratio of the water-soluble cerium salt to the polyethylene glycol with the molecular weight of 800-2000 is (1.3-3): 1; the mass ratio of the water-soluble cerium salt to the C1-C3 alkyl alcohol to the water is 1: (4-20): (6-28). According to the preparation method disclosed by the invention, the micron-sized spherical cerium oxide with the particle size of 1.5-4.5 microns can be obtained.

Description

Technical Field

[0001] The invention relates to micron-sized spherical cerium oxide and a preparation method thereof. Background Art

[0002] Cerium oxide is a light rare earth. Because of its active 4f electrons, good oxygen storage and release capacity, and its trivalent and tetravalent metal ion conversion ability, cerium oxide is widely used in solid fuel cells, catalysis, electronic device materials, grinding and polishing, etc. The morphology and size of cerium oxide have a certain influence on the performance. Among them, microsphere cerium oxide has the advantages of good fluidity and friction resistance.

[0003] There are existing methods for preparing micron-sized cerium oxide, such as the document "Hydrothermal Preparation and Performance Study of Cerium Oxide Micro-Nano Materials", in which Wang Zhuhong prepared cerium oxide with a particle size of about 5 μm by adding cerium nitrate, precipitant citric acid and a large amount of urea. This method drips a cerium salt solution into an acid solution, and then drips an alkaline solution into the above solution. The operation is relatively cumbersome, consumes a large amount of urea, and is costly.

[0004] In the document "Preparation of Micron-sized Spherical Cerium Oxide by Detonation Method", Han Zhiwei et al. used the detonation method with cerium nitrate and soheijin explosive as raw materials, and adjusted the mass fraction of cerium nitrate in the mixed explosive to prepare spherical cerium oxide of 2.2 to 4.6 μm. However, this method is dangerous due to the instability of the raw materials.

[0005] The Chinese patent application with application number 201310646000.4 discloses a method for preparing micron-sized ellipsoidal cerium oxide, which adopts a gas-liquid contact method, uses a soluble cerium salt as a raw material, and uses CTAB as a morphology regulator. The reaction is carried out in a dryer for 15 days, which is too long. Moreover, the method obtains ellipsoidal cerium oxide particles with a long axis length of 7 to 11 μm.

[0006] The Chinese patent application with application number 201510800886.2 discloses a low-temperature preparation method for micron-sized cerium oxide microspheres. The raw materials used in the method are cerium nitrate hexahydrate and urea, and the molar ratio of the two is 1:4. After the solutions of the two raw materials are mixed, betaine and deionized water are added to obtain a mixed solution, and then a reaction is carried out. The concentration of cerium salt in the reaction solution is low, and only 0.435g of cerium nitrate raw material is contained in 100mL of the reaction solution, and the reaction efficiency is not high. The diameter of the obtained cerium oxide microspheres is between 0.5 and 1μm.

[0007] The Chinese patent application with application number 201811084598.1 discloses a method for preparing micron-sized cerium oxide powder, which includes the following steps: adding a cerium-containing compound to an acidic solution to prepare a cerium salt solution; adding the cerium salt solution to a mixed solution of ethylene glycol and water, adding a surfactant after sufficient stirring, and adjusting the pH to 8-10 with ammonia water after stirring and mixing evenly; adding the above solution to a hydrothermal kettle for hydrothermal reaction for 6-10 hours, filtering, drying, and roasting the precipitate to obtain the product. The particle size of the cerium oxide obtained by this method is in the range of 0.1-25 μm, and the distribution is relatively wide.

[0008] The Chinese patent application with application number 202310901993.9 discloses a method for preparing rare earth oxide particles, comprising the following steps: 1) mixing an alkaline substance and a solution containing a citrate radical to obtain a conditioning solution; 2) adding the conditioning solution and a rare earth salt solution to a reaction vessel containing a bottom liquid in parallel to react and obtain a solid-liquid mixture containing a precursor precipitate; 3) aging, solid-liquid separation, drying, and roasting the solid-liquid mixture containing the precursor precipitate to obtain rare earth oxide particles. The particle size of the cerium oxide particles obtained in the embodiment of the preparation method is 13.46 μm. Summary of the invention

[0009] In view of this, one object of the present invention is to provide a method for preparing micron-sized spherical cerium oxide, which can obtain spherical cerium oxide with a particle size range of 1.5 to 4.5 μm. Another object of the present invention is to provide a micron-sized spherical cerium oxide prepared according to the above preparation method. The present invention adopts the following technical solution to achieve the above object.

[0010] In one aspect, the present invention provides a method for preparing micron-sized spherical cerium oxide, comprising the following steps:

[0011] 1) mixing a water-soluble cerium salt, polyethylene glycol with a molecular weight of 800 to 2000, a C1-C3 alkyl alcohol and water to obtain a preliminary mixture;

[0012] 2) placing the preliminary mixture in a reaction vessel and sealing it, and then reacting it at 160-210° C., and obtaining a solid by separation after the reaction is completed;

[0013] 3) drying and calcining the solid to obtain micron-sized spherical cerium oxide;

[0014] Wherein, the mass ratio of the water-soluble cerium salt to the polyethylene glycol with a molecular weight of 800 to 2000 is 1.3 to 3:1;

[0015] The usage ratio of water-soluble cerium salt, C1-C3 alkyl alcohol and water is 1:4-20:6-28.

[0016] According to the preparation method of the present invention, preferably, the water-soluble cerium salt is selected from one of cerium nitrate, cerium carbonate and cerium sulfate.

[0017] According to the preparation method of the present invention, preferably, the water-soluble cerium salt is cerium nitrate.

[0018] According to the preparation method of the present invention, preferably, the molecular weight of the polyethylene glycol is 800-1200.

[0019] According to the preparation method of the present invention, preferably, the C1-C3 alkyl alcohol is selected from one of methanol, ethanol, isopropanol and ethylene glycol.

[0020] According to the preparation method of the present invention, preferably, in step 2), the reaction temperature is 170-200° C., and the reaction time is 4-7 h.

[0021] According to the preparation method of the present invention, preferably, in step 2), separating and obtaining a solid after the reaction is completed comprises the following specific steps: cooling to room temperature after the reaction is completed, centrifuging the reactants, and washing the precipitate obtained by centrifugation with a C1-C3 alkyl alcohol to obtain a solid.

[0022] According to the preparation method of the present invention, preferably, in step 3), the drying temperature is 60-100° C., and the drying time is 8-16 hours.

[0023] According to the preparation method of the present invention, preferably, the calcination temperature is 450-550° C., and the calcination time is 3-6 hours.

[0024] On the other hand, the present invention also provides a micron-sized spherical cerium oxide, which is prepared according to the preparation method as described above, and is spherical or quasi-spherical, and the particle size of the cerium oxide ranges from 1.5 to 4.5 μm.

[0025] The preparation method of the present invention can obtain micron-sized spherical cerium oxide, and the particle size range of cerium oxide is 1.5 to 4.5 μm, and the particle size distribution is narrow. According to the preferred technical scheme of the present invention, the present invention adopts polyethylene glycol with a specific molecular weight distribution and a specific raw material dosage ratio, and reacts in a closed reactor, and then dries and roasts to obtain the micron-sized spherical cerium oxide of the present invention. In addition, the preparation method of the present invention has a relatively simple process, good controllability, and is conducive to popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the XRD pattern of the cerium oxide product of Example 1.

[0027] Figure 2 This is a scanning electron microscope image of the cerium oxide product of Example 1.

[0028] Figure 3This is a scanning electron microscope image of the product cerium oxide in Example 2.

[0029] Figure 4 This is a scanning electron microscope image of the product cerium oxide in Example 3.

[0030] Figure 5 This is a scanning electron microscope image of the product cerium oxide in Example 4.

[0031] Figure 6 This is a scanning electron microscope image of the product cerium oxide in Example 6.

[0032] Figure 7 This is a scanning electron microscope image of the product cerium oxide of Comparative Example 2. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0034] In the present invention, Cm-Cn refers to m to n carbon atoms, for example, C1-C3 refers to 1 to 3 carbon atoms.

[0035] The present invention provides a method for preparing micron-sized spherical cerium oxide, comprising the following steps:

[0036] (1) Preliminary mixing step; (2) Solvothermal reaction step; (3) Drying and calcining step. The following is a detailed description.

[0037] <Preliminary Mixing Step>

[0038] The water-soluble cerium salt, polyethylene glycol with a molecular weight of 800 to 2000, C1-C3 alkyl alcohol and water are mixed to obtain a preliminary mixture, which is beneficial to the next step of the reaction.

[0039] In the present invention, the water-soluble cerium salt is selected from one of cerium nitrate, cerium carbonate and cerium sulfate, preferably cerium nitrate. The water-soluble cerium salt may contain crystal water or may not contain crystal water.

[0040] In the present invention, the molecular weight of polyethylene glycol is 800 to 2000, preferably 800 to 1200, and more preferably 800 to 1000. The molecular weight is the number average molecular weight. The present invention finds that polyethylene glycol with such a molecular weight distribution is conducive to obtaining micron-sized spherical cerium oxide with a particle size in the range of 1.5 to 4.5 μm. If the molecular weight of polyethylene glycol is not within the range of the present invention, the micron-sized spherical cerium oxide of the present invention cannot be obtained.

[0041] In the present invention, the C1-C3 alkyl alcohol is selected from one of methanol, ethanol, isopropanol and ethylene glycol, preferably selected from one of ethanol and ethylene glycol, more preferably ethanol. Ethanol is preferably anhydrous ethanol. According to one embodiment of the present invention, the C1-C3 alkyl alcohol is ethanol. According to another embodiment of the present invention, the C1-C3 alkyl alcohol is ethylene glycol.

[0042] In the present invention, the mass ratio of the water-soluble cerium salt to the polyethylene glycol having a molecular weight of 800 to 2000 is 1.3 to 3.3:1, preferably 1.3 to 3:1, and more preferably 1.3 to 2.8:1. The mass ratio of the water-soluble cerium salt, the C1-C3 alkyl alcohol and water is 1:4 to 20:6 to 28. The mass ratio of the water-soluble cerium salt to the C1-C3 alkyl alcohol may be 1:5 to 20, preferably 1:6 to 18, and more preferably 1:6 to 15. The mass ratio of the water-soluble cerium salt to water may be 1:6 to 28, preferably 1:10 to 26, and more preferably 1:13 to 25.

[0043] Furthermore, the concentration of the water-soluble cerium salt in the present invention is relatively high, and in 100 mL of the preliminary mixture, the water-soluble cerium salt can reach more than 2 g, which is conducive to improving the reaction efficiency and the unit yield.

[0044] In certain preferred embodiments, the volume of water used is greater than the volume of the C1-C3 alkyl alcohol used, which is conducive to obtaining micron-sized spherical cerium oxide with a particle size ranging from 1.5 to 4.5 μm.

[0045] In the present invention, stirring may be performed during the preliminary mixing.

[0046] <Solvothermal Reaction Step>

[0047] The preliminary mixture is placed in a reactor and sealed, and then reacted at 160-210°C, and solids are obtained by separation after the reaction is completed. This is conducive to obtaining micron-sized spherical cerium oxide with a particle size ranging from 1.5 to 4.5 μm.

[0048] In the present invention, the reaction temperature may be 160 to 210° C., preferably 170 to 205° C., more preferably 180 to 200° C. The reaction time may be 4 to 7 hours, preferably 4.5 to 6.5 hours, more preferably 5 to 6 hours.

[0049] In the present invention, the separation of the solid after the reaction specifically comprises the following steps: cooling to room temperature after the reaction, centrifuging the reactants, and washing the precipitate obtained by centrifugation with a C1-C3 alkyl alcohol to obtain a solid. In this step, the C1-C3 alkyl alcohol is selected from one of methanol, ethanol, and isopropanol, preferably ethanol, such as anhydrous ethanol. The washing times can be 1 or 2 times, preferably 2 times.

[0050] <Drying and Calcination Steps>

[0051] The solid is dried and calcined to obtain micron-sized spherical cerium oxide, which is conducive to obtaining the micron-sized spherical cerium oxide of the present invention.

[0052] The drying temperature can be 60-100°C, preferably 70-90°C, more preferably 75-85°C, for example 75°C, 80°C, 85°C. The drying time can be 8-16h, preferably 10-15h, more preferably 12-13h. The roasting temperature can be 450-550°C, preferably 470-530°C, more preferably 490-510°C, for example 490°C, 500°C, 510°C. The roasting time can be 3-6h, preferably 3.5-5.5h, more preferably 4-5h.

[0053] In the present invention, the micron-sized spherical cerium oxide of the present invention can be obtained by using cerium nitrate, polyethylene glycol with a certain molecular weight distribution range, alcohol solvent and water in a specific dosage ratio, reacting in a sealed reactor, drying and roasting after separation.

[0054] The micron-sized spherical cerium oxide of the present invention is spherical or quasi-spherical, and the particle size of the cerium oxide ranges from 1.5 to 4.5 μm, preferably from 2 to 4 μm. The particle size distribution of the product cerium oxide prepared by the method of the present invention is relatively narrow.

[0055] The test methods used in the following examples are described as follows:

[0056] XRD: X'Pert PRO X-ray diffractometer was used for testing.

[0057] SEM: The images were tested using a ZEISS Sigma 500 field emission scanning electron microscope.

[0058] Example 1

[0059] 2.00 g of cerium nitrate hexahydrate, 1.50 g of polyethylene glycol 1000, 25 mL of anhydrous ethanol, and 35 mL of water were mixed uniformly to obtain a preliminary mixture.

[0060] The preliminary mixture was transferred into a reactor and sealed, and then subjected to solvent thermal reaction at 180°C for 5 hours. After the reaction was completed, it was naturally cooled to room temperature, the reactant was centrifuged, and the precipitate obtained by centrifugation was washed twice with anhydrous ethanol to obtain a solid.

[0061] The solid was dried at 80° C. for 12 h, and the dried solid was calcined at 500° C. for 4 h to obtain micron-sized spherical cerium oxide.

[0062] The XRD results (specifically SAED results) of the cerium oxide obtained in this example are shown in Figure 1 , SEM results are shown in Figure 2 . Figure 1 The peaks of cerium oxide in the sample correspond to the crystal planes (111), (200), (220), (311), (222), and (400) of the XRD cerium oxide standard card PDF#01-0800, proving that cerium oxide crystals have been successfully prepared. Figure 2 It can be seen that the product cerium oxide is a spherical body with a particle size of about 2 μm, and there are agglomerated particles with many edges and corners on the surface.

[0063] Example 2

[0064] 2.00 g of cerium nitrate hexahydrate, 1.50 g of polyethylene glycol 1000, 20 mL of anhydrous ethanol, and 40 mL of water were mixed uniformly to obtain a preliminary mixture.

[0065] The preliminary mixture was transferred into a reactor and sealed, and then subjected to solvent thermal reaction at 180°C for 5 hours. After the reaction was completed, it was naturally cooled to room temperature, the reactant was centrifuged, and the precipitate obtained by centrifugation was washed twice with anhydrous ethanol to obtain a solid.

[0066] The solid was dried at 80° C. for 12 h, and the dried solid was calcined at 500° C. for 4 h to obtain micron-sized spherical cerium oxide.

[0067] The SEM results of the product cerium oxide are shown in Figure 3 .Depend on Figure 3 It can be seen that cerium oxide is spherical with a particle size of about 2 μm, and there are also agglomerated particles with many edges and corners on the surface.

[0068] Example 3

[0069] The difference from Example 1 is that the feeding amounts are different. In this example, cerium nitrate hexahydrate is 2.50 g, polyethylene glycol 1000 is 1.50 g, anhydrous ethanol is 20 mL, and water is 40 mL.

[0070] The SEM results of the obtained cerium oxide are shown in Figure 4 .Depend on Figure 4 It can be seen that the product cerium oxide has smooth edges and is spherical with a particle size of 2 to 3 μm. At the same time, there are agglomerated particles with many edges and corners on the surface.

[0071] Example 4

[0072] The difference from Example 1 is that the feeding amount is different. In this example, cerium nitrate hexahydrate is 3.00 g, polyethylene glycol 1000 is 1.50 g, anhydrous ethanol is 20 mL, and water is 40 mL.

[0073] The SEM results of the obtained cerium oxide are shown in Figure 5 .Depend on Figure 5It can be seen that the product cerium oxide is a spherical body with a particle size of 2 to 3 μm, and there are also agglomerated particles with many edges and corners on the surface.

[0074] Example 5

[0075] The difference from Example 1 is that the feeding amount is different. In this example, cerium nitrate hexahydrate is 2.00 g, polyethylene glycol 1000 is 1.00 g, anhydrous ethanol is 15 mL, and water is 45 mL.

[0076] The obtained cerium oxide product is a spherical body with a particle size of 2 to 4 μm, and there are agglomerated particles with many edges and corners on the surface.

[0077] Example 6

[0078] 2.00 g of cerium nitrate hexahydrate, 1.00 g of polyethylene glycol 1000, 15 mL of ethylene glycol, and 45 mL of water were mixed uniformly to obtain a preliminary mixture.

[0079] The preliminary mixture was transferred into a reactor and sealed, and then subjected to solvent thermal reaction at 200° C. for 5 h. After the reaction was completed, the mixture was naturally cooled to room temperature, the reactants were centrifuged, and the precipitate obtained by centrifugation was washed twice with anhydrous ethanol to obtain a solid.

[0080] The solid was dried at 80° C. for 12 h, and the dried solid was calcined at 500° C. for 4 h to obtain micron-sized cerium oxide.

[0081] The SEM results of the product cerium oxide are shown in Figure 6 The product cerium oxide is a spherical body with a particle size of about 2 μm, and there are also agglomerated particles with many edges and corners on the surface.

[0082] Comparative Example 1

[0083] 2.00 g of cerium nitrate hexahydrate, 2.00 g of polyethylene glycol 1000, 20 mL of ethylene glycol, and 40 mL of water were mixed uniformly to obtain a preliminary mixture.

[0084] The preliminary mixture was transferred into a reactor and sealed, and then subjected to solvent thermal reaction at 180°C for 5 hours. After the reaction was completed, it was naturally cooled to room temperature and the reactants were centrifuged. No precipitation was produced after centrifugation.

[0085] Comparative Example 2

[0086] The difference from Example 1 is that the feeding amounts are different. In this example, cerium nitrate hexahydrate is 2.75 g, polyethylene glycol 1000 is 1.00 g, anhydrous ethanol is 42 mL, and water is 14 mL.

[0087] The SEM results of the obtained cerium oxide are shown in Figure 7 .Depend on Figure 7 It can be seen that the product cerium oxide is a spherical body with a particle size of 1 μm, and the spherical body is composed of agglomerates of balls of about 200 nm.

[0088] Table 1

[0089]

[0090] It can be seen that the preparation method of the present invention can obtain micron-sized spherical cerium oxide with a particle size of 1.5 to 4.5 μm, preferably 2 to 4 μm, and the particle size distribution of the obtained cerium oxide product is relatively narrow.

[0091] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing micron-sized spherical cerium oxide, characterized in that: The steps include: 1) mixing a water-soluble cerium salt, polyethylene glycol with a molecular weight of 800 to 2000, a C1-C3 alkyl alcohol and water to obtain a preliminary mixture; 2) placing the preliminary mixture in a reaction vessel and sealing it, and then reacting it at 160-210° C., and obtaining a solid by separation after the reaction is completed; 3) drying and calcining the solid to obtain micron-sized spherical cerium oxide; Wherein, the mass ratio of the water-soluble cerium salt to the polyethylene glycol with a molecular weight of 800 to 2000 is 1.3 to 3:1; The mass ratio of the water-soluble cerium salt, the C1-C3 alkyl alcohol and water is 1:4-20:6-28.

2. The preparation method according to claim 1, characterized in that: The water-soluble cerium salt is selected from one of cerium nitrate, cerium carbonate and cerium sulfate.

3. The preparation method according to claim 1, characterized in that: The water-soluble cerium salt is cerium nitrate.

4. The preparation method according to claim 1, characterized in that: The molecular weight of the polyethylene glycol is 800-1200.

5. The preparation method according to claim 1, characterized in that: The C1-C3 alkyl alcohol is selected from one of methanol, ethanol, isopropanol and ethylene glycol.

6. The preparation method according to claim 1, characterized in that: In step 2), the reaction temperature is 170-200° C. and the reaction time is 4-7 hours.

7. The preparation method according to claim 1, characterized in that: In step 2), separating and obtaining a solid after the reaction is completed comprises the following specific steps: cooling to room temperature after the reaction is completed, centrifuging the reactants, and washing the precipitate obtained by centrifugation with a C1-C3 alkyl alcohol to obtain a solid.

8. The preparation method according to claim 1, characterized in that: In step 3), the drying temperature is 60-100° C. and the drying time is 8-16 hours.

9. The preparation method according to claim 1, characterized in that: The calcination temperature is 450-550°C, and the calcination time is 3-6 hours.

10. A micron-sized spherical cerium oxide, characterized in that: The cerium oxide is prepared according to the preparation method according to any one of claims 1 to 9, is spherical or quasi-spherical, and has a particle size ranging from 1.5 to 4.5 μm.

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