Nanospherical ceria, and preparation method and application thereof

Abstract

The application provides a kind of nanometer spherical cerium dioxide and its preparation method and application.The preparation method comprises the following steps: adding dispersant in cerium ion precursor slurry with pH of 0.1-4.0 to obtain a mixed solution, and then performing hydrothermal reaction on the mixed solution, and finally obtaining the spherical cerium dioxide by calcination.The spherical nanometer cerium dioxide prepared by the application has high sphericity, good dispersibility between particles, uniform and concentrated particle size distribution, and the size can be controlled between 30-500nm.

Description

Technical Field

[0001] This invention belongs to the technical field of nano-rare earth material preparation, specifically relating to a nano-spherical cerium dioxide, its preparation method, and its application. Background Technology

[0002] Cerium dioxide, a typical light rare earth oxide, possesses excellent redox properties due to its unique crystal structure and is widely used in various functional materials, such as polishing materials, catalysts, lubricants, automotive exhaust purifiers, ultraviolet absorbers, and electronic ceramic materials. Its application development prospects are very broad. Currently, the morphology, size, and functional applications of nanoscale cerium dioxide materials have become research hotspots.

[0003] In recent years, researchers have synthesized cerium dioxide of different morphologies and sizes using various methods, such as submicron or nanoscale spheres, rods, cubes, and petals. Currently, there are many mature methods for preparing nano-cerium dioxide materials, which can be broadly classified into three categories: gas-phase methods, liquid-phase methods, and solid-phase methods.

[0004] The gas-phase method refers to the chemical reaction between multiple elements or compounds under gas-phase conditions. It is a method for preparing nanoscale oxides. The products prepared by the gas-phase method have low agglomeration and high purity, but the yield is low, the equipment cost is expensive, and the reaction conditions are harsh.

[0005] The liquid-phase method involves preparing nanoparticles by controlling various reaction conditions in a liquid environment to form precursors, followed by drying and calcination. This method boasts simple production equipment, produces high-purity powders with less agglomeration, requires no stringent physical conditions such as high vacuum, and is easily scalable for industrial production, making it the most widely used method for nanoparticle preparation. Liquid-phase methods mainly include precipitation, solvothermal, sol-gel, and microemulsion methods.

[0006] The solid-state method refers to the process of obtaining nanoparticles by forming precursors through solid compounds or solid-state reactions and then decomposing them at high temperatures. While the equipment used is simple and the operation is convenient, the resulting powders often lack purity and have a wide particle size distribution, making it suitable for applications with lower requirements.

[0007] CN114477264A discloses a method for preparing cerium dioxide nanoparticles with a particle size of 50-150 nm using a sol-gel method. The preparation method is simple and requires low equipment, but the nanoparticles are severely agglomerated, have no fixed morphology, and have a low sphericity.

[0008] CN113003601A discloses a method for preparing spherical nano-cerium dioxide, which uses a high-speed shear disperser at 40-200℃ and introduces an oxidizing gas to react and prepare monodisperse, spherical nano-cerium dioxide with a particle size of 40-200nm. However, this method requires the introduction of an oxidizing gas, and the process is relatively complex and has high operational requirements.

[0009] CN101244837A discloses a method for preparing high-purity nano-cerium dioxide, which combines hydrothermal reaction and solid-state reaction to prepare nano-cerium dioxide with uniform particles and high purity. The hydrothermal reaction needs to be carried out at 150-180℃ for 24-72 hours, which is a long reaction time and has high energy consumption.

[0010] CN111434379B discloses a method for preparing oil-soluble monodisperse nano-cerium dioxide. The cerium dioxide crystals have small particle size, monodispersity, uniform particle size distribution, good dispersibility, high purity, and high stability. The disadvantage is that the preparation process uses a large amount of organic solvent, the reaction conditions are harsh, the operation requirements are high, and it is not suitable for industrial production.

[0011] Therefore, developing a method for preparing nanoscale cerium dioxide powder with good dispersibility, controllable particle size, and uniformity is an important research direction in this field. Summary of the Invention

[0012] The purpose of this invention is to provide a nanosphere of cerium dioxide with good dispersibility, controllable particle size, and uniformity, as well as its preparation method and application.

[0013] To achieve this objective, the present invention employs the following technical solution:

[0014] One objective of this invention is to provide a method for preparing nano-spherical cerium dioxide, the method comprising the following steps:

[0015] A dispersant was added to a cerium ion precursor slurry with a pH of 0.1–4.0 to obtain a mixed solution. The mixed solution was subjected to a hydrothermal reaction and then calcined to obtain the nano-spherical cerium dioxide.

[0016] This invention selects a cerium ion precursor slurry with a weak acid system of pH 0.1 to 4.0, and adds a dispersant to the cerium ion precursor slurry in the weak acid system to effectively reduce interparticle agglomeration and control particle size growth. After dispersion, a mixed solution is obtained. The mixed solution is subjected to a hydrothermal reaction, and the prepared cerium oxide particles have better uniformity and sphericity. After calcination treatment, the crystallinity and hardness of the material are improved.

[0017] As a preferred technical solution of the present invention, the method for preparing the cerium ion precursor slurry includes: adding a surfactant to a pretreated cerium ion solution and mixing to obtain the cerium ion precursor slurry.

[0018] Preferably, the mass ratio of the cerium ion solution, dispersant, and surfactant is (5-20):(30-100):(0-3), wherein the mass ratio can be 5:30:0, 5:40:1, 5:50:2, 5:60:3, 5:70:1, 5:80:2, 5:90:3, 5:100:1, 10:30:2, 10:40:3, 10:50:0, 10:60:1, 10:70:2, 10:80:3, 10:90:0, 10:100:1, 15:30:2, 15:40:3, 15:50:0, 15:60:1, 15:70:2, 15:80:3, 15:90:0, 15:100:1, 20:30:2, 20:40:3, 20:50:0, 20:60:1, 20:70:2, 20:80:3, 20:90:0, or 20:100:2, etc., but not limited to the listed values; other unlisted values ​​within this range also apply.

[0019] Preferably, the method for mixing the surfactant with the cerium ion solution includes ultrasonic mixing.

[0020] In this invention, a surfactant is added first, followed by a dispersant, in a specific order. Since the surfactant can control particle growth, adding the dispersant can reduce particle aggregation.

[0021] As a preferred technical solution of the present invention, the pretreatment method includes: adding acid and water to the cerium ion solution and mixing them.

[0022] Under alkaline conditions, cerium ions readily form cerium hydroxide precipitate, resulting in rapid particle growth and severe particle aggregation. Therefore, this invention pretreats the cerium ion solution with acid to reduce precipitate formation.

[0023] Preferably, the acid includes any one or a combination of at least two of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, or tartaric acid, wherein typical but non-limiting examples of the combination include: a combination of formic acid and acetic acid, a combination of acetic acid and propionic acid, a combination of propionic acid and oxalic acid, a combination of oxalic acid and citric acid, or a combination of citric acid and tartaric acid, and preferably a combination of any one or at least two of acetic acid, propionic acid, or oxalic acid.

[0024] Preferably, the concentration of the acid is 0.1 to 15 mol / L, wherein the concentration can be 0.1 mol / L, 2 mol / L, 4 mol / L, 6 mol / L, 8 mol / L, 10 mol / L, 12 mol / L, 14 mol / L or 15 mol / L, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] Preferably, the volume ratio of acid to water is (0.5-40):(1-60), wherein the volume ratio can be 0.5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 0.5:10, 0.5:20, 0.5:30, 0.5:40, 0.5:50, 0.5:60, 10:1, 10:10, 10:20, 10:30, 10:40, 10:50, 10:60, 20:1, 20:10, 20:30, 20:50, 30:1, 30:20, 30:40, 30:50, 40:1, 40:10, 40:30, or 40:60, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0026] The product prepared by the present invention exhibits severe agglomeration when the volume ratio of acid to water is too large, and poor particle uniformity when the volume ratio is too small.

[0027] As a preferred embodiment of the present invention, the solute in the cerium ion solution is a cerium source.

[0028] Preferably, the cerium source includes any one or a combination of at least two of cerium chloride, cerium nitrate (III), cerium nitrate (IV), cerium sulfate (III), cerium sulfate (IV), cerium ammonium nitrate, or cerium hydroxide. Typical but non-limiting examples of the combination include: a combination of cerium chloride and cerium nitrate (III), a combination of cerium nitrate (III) and cerium sulfate (III), or a combination of cerium sulfate (III) and cerium hydroxide, preferably cerium chloride and / or cerium nitrate (III).

[0029] Preferably, the concentration of the cerium ion solution is 0.1–9.0 mol / L, wherein the concentration can be 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, 5.0 mol / L, 6.0 mol / L, 7.0 mol / L, 8.0 mol / L, or 9.0 mol / L, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0030] Preferably, the surfactant comprises any one or a combination of at least two of diethylenediaminepentaacetic acid, ethylenediaminetetraacetic acid, hydroxyethyl ethylenediaminetriacetic acid, ethylenediaminetetraacetic acid, ethylenediaminediaacetic acid, or ethylenediaminetetraoxic acid. Typical but non-limiting examples of such combinations include: a combination of diethylenediaminepentaacetic acid and ethylenediaminetetraacetic acid, a combination of ethylenediaminetetraacetic acid and hydroxyethyl ethylenediaminetriacetic acid, a combination of hydroxyethyl ethylenediaminetriacetic acid and ethylenediaminetetraacetic acid, a combination of ethylenediaminetetraacetic acid and ethylenediaminediaacetic acid, or a combination of ethylenediaminediaacetic acid and ethylenediaminetetraoxic acid, etc., and is preferably any one or a combination of at least two of diethylenediaminepentaacetic acid, ethylenediaminetetraacetic acid, or ethylenediaminetetraoxic acid.

[0031] Preferably, the dispersant comprises any one or a combination of at least two of propylene glycol, polyethylene glycol, glycerin, ethylene glycol, diethylene glycol monobutyl ether, or diethylene glycol monobutyl ether. Typical but non-limiting examples of such combinations include combinations of propylene glycol and polyethylene glycol, combinations of polyethylene glycol and glycerin, combinations of glycerin and ethylene glycol, combinations of ethylene glycol and diethylene glycol monobutyl ether, or combinations of diethylene glycol monobutyl ether and diethylene glycol monobutyl ether, etc., and preferably any one or a combination of at least two of propylene glycol, glycerin, or ethylene glycol.

[0032] As a preferred technical solution of the present invention, the hydrothermal reaction time is 0.1 to 72 hours, wherein the time can be 0.1 hours, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours, or 72 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.5 to 5 hours.

[0033] Preferably, the temperature of the hydrothermal reaction is 20 to 300°C, wherein the temperature can be 20°C, 50°C, 100°C, 150°C, 200°C, 250°C or 300°C, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 100 to 250°C.

[0034] The product prepared by the hydrothermal reaction of this invention exhibits severe agglomeration and poor sphericity when the temperature is too high, and the reaction cannot proceed when the temperature is too low.

[0035] As a preferred technical solution of the present invention, after the hydrothermal reaction, an intermediate product is obtained, and the intermediate product is sequentially separated and dried before calcination.

[0036] Preferably, the separation method includes: centrifuging the intermediate product and washing the lower precipitate.

[0037] The present invention uses deionized water and anhydrous ethanol for washing. The washing time with deionized water is 1 to 20 minutes, and the number of washing cycles is 1 to 6. The washing time with anhydrous ethanol is 1 to 20 minutes, and the number of washing cycles is 1 to 6.

[0038] Preferably, the centrifugation time is 1 to 50 minutes, wherein the time can be 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, or 50 minutes, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the centrifugation speed is 300–20000 r / min, wherein the speed can be 300 r / min, 500 r / min, 1000 r / min, 1500 r / min, 2000 r / min, 3000 r / min, 4000 r / min, 5000 r / min, 6000 r / min, 7000 r / min, 8000 r / min, 9000 r / min, 10000 r / min, 11000 r / min, 12000 r / min, 13000 r / min, 14000 r / min, 15000 r / min, 16000 r / min, 17000 r / min, 18000 r / min, 19000 r / min, or 20000 r / min, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0040] Preferably, the drying temperature is 20 to 300°C, wherein the temperature can be 20°C, 30°C, 50°C, 100°C, 150°C, 200°C, 250°C or 300°C, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0041] As a preferred embodiment of the present invention, the calcination temperature is 70–800°C. The temperature can be 70°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. Preferably, the temperature is 300–600°C.

[0042] If the calcination temperature is too high, the particles will agglomerate severely; if the calcination temperature is too low, the crystallinity will be poor and the hardness will be low.

[0043] Preferably, the calcination time is 0.1 to 24 hours, wherein the time can be 0.1 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 8 hours, 12 hours, 16 hours, 20 hours or 24 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.5 to 5 hours.

[0044] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0045] (1) A dispersant was added to a cerium ion precursor slurry with a pH of 0.1 to 4.0 to obtain a mixed solution;

[0046] The method for preparing the cerium ion precursor slurry includes: adding a surfactant to a pretreated cerium ion solution and mixing to obtain the cerium ion precursor slurry;

[0047] The pretreatment method includes: adding acid and water to the cerium ion solution and mixing them;

[0048] (2) The mixed solution in step (1) is subjected to a hydrothermal reaction for 0.1 to 72 hours and at a temperature of 20 to 300°C to obtain an intermediate product. The intermediate product is then separated and dried sequentially, and calcined at 70 to 800°C to obtain the spherical cerium dioxide.

[0049] A second objective of this invention is to provide a nano-spherical cerium dioxide, wherein the nano-spherical cerium dioxide is prepared by the preparation method described in one objective.

[0050] The third objective of this invention is to provide an application of the nano-spherical cerium dioxide as described in the second objective, wherein the nano-spherical cerium dioxide is applied in the field of nano-rare earth materials.

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

[0052] (1) The nano-cerium dioxide prepared by this invention has high sphericity, good inter-particle dispersion, uniform and concentrated particle size distribution, and the size can be controlled between 30 and 500 nm.

[0053] (2) The preparation method of cerium dioxide in this invention is simple, low in cost, and conducive to industrial production. The reaction time during the preparation process is short and the requirements for equipment are low. Attached Figure Description

[0054] Figure 1 This is a flowchart of the preparation method of spherical nano-cerium dioxide as shown in Example 1 of the present invention.

[0055] Figure 2 This is the XRD pattern of the spherical cerium dioxide nanoparticles prepared in Example 1 of this invention.

[0056] Figure 3 This is the SME diagram of the spherical cerium dioxide nanoparticles prepared in Example 1 of this invention.

[0057] Figure 4 This is a SEM image of the spherical cerium dioxide nanoparticles prepared in Example 4 of this invention.

[0058] Figure 5 This is a SEM image of the spherical cerium dioxide nanoparticles prepared in Example 5 of this invention.

[0059] Figure 6 This is a SEM image of the spherical cerium dioxide nanoparticles prepared in Example 6 of this invention.

[0060] Figure 7 This is a SEM image of the spherical cerium dioxide nanoparticles prepared in Example 7 of this invention. Detailed Implementation

[0061] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0062] Example 1

[0063] This embodiment provides a method such as Figure 1 The method for preparing nano-spherical cerium dioxide shown includes the following steps:

[0064] (1) Prepare a 2.8 mol / L Ce(NO3)3·6H2O solution and add an appropriate amount of acetic acid to mix the solution evenly. The volume ratio of acetic acid to deionized water is 1:1 to obtain a pretreated cerium ion solution. Add 0.5 g of surfactant ethylenediaminetetraacetic acid to 4 mL of the pretreated cerium ion solution and mix with ultrasound to obtain a milky white precursor slurry. Slowly add 60 mL of dispersant ethylene glycol to the milky white precursor slurry and mix the solution thoroughly under stirring and ultrasound to obtain a mixed solution.

[0065] (2) The mixed solution described in step (1) was transferred to a hydrothermal reactor and hydrothermally reacted at 150°C for 2.5 h. After naturally cooling to room temperature, the hydrothermal product was centrifuged and washed independently with deionized water and anhydrous ethanol for 10 min and 2 times respectively to obtain an intermediate product. The intermediate product was dried in an 80°C forced-air drying oven and then calcined in a muffle furnace at 400°C for 2 h. After cooling to room temperature, it was ground to finally obtain nano-spherical CeO2 particles.

[0066] The XRD pattern of the nanosphere CeO2 particles prepared in this embodiment is shown below. Figure 2 As shown, the obtained nano-CeO2 is a pure CeO2 phase. The SEM image of the nano-spherical CeO2 particles prepared in this embodiment is shown below. Figure 3 As shown, through Figure 3 It is evident that the particles have uniform size and good dispersibility.

[0067] Example 2

[0068] This embodiment provides a method for preparing nano-spherical cerium dioxide, the preparation method comprising the following steps:

[0069] (1) Prepare a 2.8 mol / L Ce(NO3)3·6H2O solution and add an appropriate amount of oxalic acid to mix the solution evenly. The volume ratio of oxalic acid to deionized water is 1:1 to obtain a pretreated cerium ion solution. Add 0.5 g of the surfactant diethylenediaminepentaacetic acid to 4 mL of the pretreated cerium ion solution and mix with ultrasound to obtain a milky white precursor slurry. Slowly add 60 mL of the dispersant glycerol to the milky white precursor slurry and mix the solution thoroughly under stirring and ultrasound to obtain a mixed solution.

[0070] (2) The mixed solution described in step (1) is transferred to a hydrothermal reactor and hydrothermally reacted at 300°C for 0.1 h. After naturally cooling to room temperature, the hydrothermal product is centrifuged and washed independently with deionized water and anhydrous ethanol for 10 min and 2 times respectively to obtain an intermediate product. The intermediate product is dried in a 65°C forced-air drying oven and then calcined in a 70°C muffle furnace for 2 h. After cooling to room temperature, it is ground to finally obtain nano-spherical CeO2 particles.

[0071] Example 3

[0072] This embodiment provides a method for preparing nano-spherical cerium dioxide, the preparation method comprising the following steps:

[0073] (1) Prepare a 2.8 mol / L Ce(NO3)3·6H2O solution and add an appropriate amount of propionic acid to mix the solution evenly. The volume ratio of propionic acid to deionized water is 1:1 to obtain a pretreated cerium ion solution. Add 0.5 g of surfactant ethylenediaminetetraethylenedioxic acid to 4 mL of the pretreated cerium ion solution and mix with ultrasound to obtain a milky white precursor slurry. Slowly add 60 mL of dispersant polyethylene glycol to the milky white precursor slurry and mix the solution thoroughly under stirring and ultrasound to obtain a mixed solution.

[0074] (2) The mixed solution described in step (1) is transferred to a hydrothermal reactor and hydrothermally reacted at 20°C for 72 hours. After naturally cooling to room temperature, the hydrothermal product is centrifuged and washed independently with deionized water and anhydrous ethanol for 10 minutes and 2 times respectively to obtain an intermediate product. The intermediate product is dried in a 300°C forced-air drying oven and then calcined in an 800°C muffle furnace for 2 hours. After cooling to room temperature, it is ground to finally obtain nano-spherical CeO2 particles.

[0075] Example 4

[0076] This embodiment provides a method for preparing nano-spherical cerium dioxide, the preparation method comprising the following steps:

[0077] (1) Prepare a 5.6 mol / L Ce(NO3)3·6H2O solution and add an appropriate amount of acetic acid to mix the solution evenly. The volume ratio of acetic acid to deionized water is 2:1 to obtain a pretreated cerium ion solution. Slowly add 60 mL of dispersant ethylene glycol to 3 mL of the pretreated cerium ion solution and mix the solution thoroughly under stirring and sonication to obtain a mixed solution.

[0078] (2) The mixed solution described in step (1) is transferred to a hydrothermal reactor and hydrothermally reacted at 150°C for 2.5 h. After naturally cooling to room temperature, the hydrothermal product is centrifuged and washed twice with anhydrous ethanol and deionized water to obtain an intermediate product. The intermediate product is dried in an 80°C forced-air drying oven and then calcined in a 400°C muffle furnace for 2 h. After cooling to room temperature, it is ground to finally obtain nano-spherical CeO2 particles.

[0079] The SEM image of the nanosphere CeO2 particles prepared in this embodiment is shown below. Figure 4 As shown, through Figure 4 It is evident that the particles have uniform size and good dispersibility.

[0080] Example 5

[0081] This embodiment provides a method for preparing nano-spherical cerium dioxide, the preparation method comprising the following steps:

[0082] (1) Prepare a 2.8 mol / L Ce(NO3)3·6H2O solution and add an appropriate amount of acetic acid to mix the solution evenly. The volume ratio of acetic acid to deionized water is 1:1 to obtain a pretreated cerium ion solution. Slowly add 60 mL of dispersant ethylene glycol to 4 mL of the pretreated cerium ion solution and mix the solution thoroughly under stirring and sonication to obtain a mixed solution.

[0083] (2) The mixed solution described in step (1) is transferred to a hydrothermal reactor and hydrothermally reacted at 150°C for 2.5 h. After naturally cooling to room temperature, the hydrothermal product is centrifuged and washed twice with anhydrous ethanol and deionized water to obtain an intermediate product. The intermediate product is dried in an 80°C forced-air drying oven and then calcined in a 400°C muffle furnace for 2 h. After cooling to room temperature, it is ground to finally obtain nano-spherical CeO2 particles.

[0084] The SEM image of the nanosphere CeO2 particles prepared in this embodiment is shown below. Figure 5 As shown, through Figure 5 It is evident that the particles have uniform size and good dispersibility.

[0085] Example 6

[0086] This embodiment provides a method for preparing nano-spherical cerium dioxide, the preparation method comprising the following steps:

[0087] (1) Prepare a 1.4 mol / L Ce(NO3)3·6H2O solution and add an appropriate amount of acetic acid to mix the solution evenly. The volume ratio of acetic acid to deionized water is 1:2 to obtain a pretreated cerium ion solution. Slowly add 60 mL of dispersant ethylene glycol to 6 mL of the pretreated cerium ion solution and mix the solution thoroughly under stirring and sonication to obtain a mixed solution.

[0088] (2) The mixed solution described in step (1) is transferred to a hydrothermal reactor and hydrothermally reacted at 150°C for 2.5 h. After naturally cooling to room temperature, the hydrothermal product is centrifuged and washed independently with deionized water and anhydrous ethanol for 10 min and 2 times respectively to obtain an intermediate product. The intermediate product is dried in an 80°C forced-air drying oven and then calcined in a muffle furnace at 400°C for 2 h. After cooling to room temperature, it is ground to finally obtain nano-spherical CeO2 particles.

[0089] The SEM image of the nanosphere CeO2 particles prepared in this embodiment is shown below. Figure 6 As shown, through Figure 6 It is evident that the particles have uniform size and good dispersibility.

[0090] Example 7

[0091] This embodiment provides a method for preparing nano-spherical cerium dioxide, the preparation method comprising the following steps:

[0092] (1) Prepare a 0.7 mol / L Ce(NO3)3·6H2O solution and add an appropriate amount of acetic acid to mix the solution evenly. The volume ratio of acetic acid to deionized water is 1:4 to obtain a pretreated cerium ion solution. Slowly add 60 mL of dispersant ethylene glycol to 10 mL of the pretreated cerium ion solution and mix the solution thoroughly under stirring and sonication to obtain a mixed solution.

[0093] (2) The mixed solution described in step (1) is transferred to a hydrothermal reactor and hydrothermally reacted at 150°C for 2.5 h. After naturally cooling to room temperature, the hydrothermal product is centrifuged and washed independently with deionized water and anhydrous ethanol for 10 min and 2 times respectively to obtain an intermediate product. The intermediate product is dried in an 80°C forced-air drying oven and then calcined in a muffle furnace at 400°C for 2 h. After cooling to room temperature, it is ground to finally obtain nano-spherical CeO2 particles.

[0094] The SEM image of the nanosphere CeO2 particles prepared in this embodiment is shown below. Figure 7 As shown, through Figure 7It is evident that the particles have uniform size and good dispersibility.

[0095] Example 8

[0096] Except for not pretreating the Ce(NO3)3·6H2O solution, all other conditions in this embodiment are the same as in Example 1.

[0097] Example 9

[0098] In this embodiment, all conditions are the same as in Example 1, except that the volume ratio of acetic acid and deionized water is replaced with 1:60.

[0099] Example 10

[0100] In this embodiment, all conditions are the same as in Example 1, except that the volume ratio of acetic acid to deionized water is replaced with 40:1.

[0101] Example 11

[0102] In this embodiment, all conditions are the same as in Example 1, except that ethylenediaminetetraacetic acid and ethylene glycol are added together to the cerium ion solution.

[0103] Comparative Example 1

[0104] Except for the fact that the intermediate product was not subjected to hydrothermal reaction and was directly calcined in a muffle furnace at 400°C for 2 hours, the conditions for this comparative example were the same as those for Example 1.

[0105] Comparative Example 2

[0106] The conditions for this comparative example were the same as those for Example 1, except that the calcination in a muffle furnace at 400°C for 2 hours was not performed.

[0107] Comparative Example 3

[0108] In this comparative example, the mixed solution described in step (1) was adjusted to pH 9.0 with sodium hydroxide and then subjected to a hydrothermal reaction. All other conditions were the same as in Example 1.

[0109] The average particle size and particle size uniformity of the cerium dioxide prepared in Examples 1-11 and Comparative Examples 1-3 were tested, and the test results are shown in Table 1.

[0110] Among them, in the particle size distribution, it can be determined by D 10 D 50 and D 90 Let's represent them separately, D 10 D 50 and D 90 The representative meanings are 10%, 50%, and 90% of the measured particle size values. The method for calculating particle size uniformity distribution is (D 90 -D 10 ) / 2D50 When (D) 90 -D 10 ) / 2D 50 The smaller the value, the better the particle size uniformity.

[0111] Table 1

[0112] Average particle size / nm Uniformity Example 1 44 0.32 Example 2 50 0.43 Example 3 48 0.38 Example 4 37 0.29 Example 5 70 0.28 Example 6 152 0.31 Example 7 353 0.37 Example 8 264 0.83 Example 9 607 0.76 Example 10 379 0.62 Example 11 51 0.47 Comparative Example 1 645 1.21 Comparative Example 2 49 0.35 Comparative Example 3 738 0.88

[0113] As can be seen from the data changes in Table 1, the addition of an appropriate amount of dispersant in Examples 1-3 resulted in smaller cerium dioxide particle sizes in the prepared products.

[0114] Examples 4-7 show that as the concentration of cerium nitrate increases, the particle size increases, while the uniformity remains almost constant.

[0115] In Example 8, without acid pretreatment of the Ce(NO3)3·6H2O solution, the cerium dioxide product exhibited very poor homogeneity and severe interparticle agglomeration.

[0116] In Examples 9-10, during the pretreatment process, if the volume ratio of acid to water is too high or too low, the cerium dioxide product will agglomerate severely and have poor uniformity.

[0117] In Example 11, the dispersant and surfactant were added together to a Ce(NO3)3·6H2O solution. The uniformity of the product cerium dioxide was poor, but the particle size variation was small.

[0118] Comparative Example 1 did not undergo hydrothermal reaction with the intermediate product, and the resulting cerium dioxide particles were large and had very poor uniformity.

[0119] Comparative Example 2, which was not calcined, produced cerium dioxide with a particle size approximately 10% larger than that produced after calcination.

[0120] Comparative Example 3 synthesized cerium dioxide particles using a hydrothermal reaction under alkaline conditions. The particles were very large and had poor uniformity in particle size distribution.

[0121] The applicant declares that the above description is only a specific embodiment 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing nano-spherical cerium dioxide, characterized in that, The preparation method includes the following steps: A dispersant was added to a cerium ion precursor slurry with a pH of 0.1 to 4.0 to obtain a mixed solution. The mixed solution was subjected to a hydrothermal reaction and then calcined to obtain the nano-spherical cerium dioxide. The method for preparing the cerium ion precursor slurry includes: adding a surfactant to a pretreated cerium ion solution and mixing to obtain the cerium ion precursor slurry; The pretreatment method includes: adding acid and water to the cerium ion solution and mixing them; The surfactant includes any one or a combination of at least two of diethylenediaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, ethylenediaminetetraacetic acid, ethylenediaminediaacetic acid, or ethylenediaminetetraoxic acid. The volume ratio of the acid to water is (1~2):(1~4).

2. The preparation method according to claim 1, characterized in that, The mass ratio of the cerium ion solution, dispersant and surfactant is (5~20):(30~100):(1~3).

3. The preparation method according to claim 1, characterized in that, The method for mixing the surfactant with the cerium ion solution includes ultrasonic mixing.

4. The preparation method according to claim 1, characterized in that, The acid includes any one or a combination of at least two of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, or tartaric acid.

5. The preparation method according to claim 4, characterized in that, The acid is any one or a combination of at least two of acetic acid, propionic acid, or oxalic acid.

6. The preparation method according to claim 1, characterized in that, The concentration of the acid is 0.1~15 mol / L.

7. The preparation method according to claim 1, characterized in that, The solute in the cerium ion solution is a cerium source.

8. The preparation method according to claim 7, characterized in that, The cerium source includes any one or a combination of at least two of cerium chloride, cerium nitrate (III), cerium nitrate (IV), cerium sulfate (III), cerium sulfate (IV), cerium ammonium nitrate, or cerium hydroxide.

9. The preparation method according to claim 8, characterized in that, The cerium source is cerium chloride and / or cerium nitrate (III).

10. The preparation method according to claim 1, characterized in that, The concentration of the cerium ion solution is 0.1~9.0 mol / L.

11. The preparation method according to claim 1, characterized in that, The surfactant is any one or a combination of at least two of diethylenediaminepentaacetic acid, ethylenediaminetetraacetic acid, or ethylenediaminetetraoxic acid.

12. The preparation method according to claim 1, characterized in that, The dispersant includes any one or a combination of at least two of propylene glycol, polyethylene glycol, glycerin, ethylene glycol, or diethylene glycol monobutyl ether.

13. The preparation method according to claim 1, characterized in that, The hydrothermal reaction time is 0.1~72h.

14. The preparation method according to claim 13, characterized in that, The hydrothermal reaction takes 0.5 to 5 hours.

15. The preparation method according to claim 1, characterized in that, The temperature of the hydrothermal reaction is 20~300℃.

16. The preparation method according to claim 15, characterized in that, The temperature of the hydrothermal reaction is 100~250℃.

17. The preparation method according to claim 1, characterized in that, After the hydrothermal reaction, an intermediate product is obtained. The intermediate product is then separated and dried sequentially, followed by calcination.

18. The preparation method according to claim 17, characterized in that, The separation method includes: centrifuging the intermediate product and washing the lower precipitate.

19. The preparation method according to claim 18, characterized in that, The centrifugation process takes 1 to 50 minutes.

20. The preparation method according to claim 18, characterized in that, The centrifugal separation process is carried out at a speed of 300~20000 r / min.

21. The preparation method according to claim 17, characterized in that, The drying temperature is 20~300℃.

22. The preparation method according to claim 1, characterized in that, The calcination temperature is 70~800℃.

23. The preparation method according to claim 22, characterized in that, The calcination temperature is 300~600℃.

24. The preparation method according to claim 1, characterized in that, The calcination time is 0.1~24h.

25. The preparation method according to claim 24, characterized in that, The calcination time is 0.5~5h.

26. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) A dispersant was added to a cerium ion precursor slurry with a pH of 0.1 to 4.0 to obtain a mixed solution; The method for preparing the cerium ion precursor slurry includes: adding a surfactant to a pretreated cerium ion solution and mixing to obtain the cerium ion precursor slurry; The pretreatment method includes: adding acid and water to the cerium ion solution and mixing them; (2) The mixed solution in step (1) is subjected to a hydrothermal reaction for 0.1 to 72 hours and at a temperature of 20 to 300°C to obtain an intermediate product. The intermediate product is then separated and dried sequentially, and calcined at 70 to 800°C to obtain the nano-spherical cerium dioxide.

27. A nano-spherical cerium dioxide, characterized in that, The spherical cerium dioxide is prepared by the preparation method according to any one of claims 1-26.

28. An application of the nano-spherical cerium dioxide as described in claim 27, characterized in that, The spherical cerium dioxide is used in the field of nano-rare earth materials.

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