Small-particle spherical cerium carbonate and preparation method thereof
By adjusting the hydrothermal reaction conditions in the hydrothermal method, small-grain spherical cerium carbonate with a median diameter of 1.98-3.65 μm and high spherical morphology were successfully prepared, which solved the problems of low product purity and uneven particle size in the prior art, and improved the performance of the product.
Patent Information
- Application Number
- CN202510082230.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2025-04-29
AI Technical Summary
The prior art is difficult to effectively prepare small-grain spherical cerium carbonate, resulting in low product purity, uneven particle size, and difficulty in controlling spherical morphology.
By adjusting the reaction crystallization temperature, reaction crystallization time, reactant concentration and molar ratio by hydrothermal method, small spherical cerium carbonate with a median diameter of 1.98-3.65 μm, a particle size distribution PDI of 0.77-1.11, and a spherical degree S of 0.91-0.96 were prepared.
The preparation of cerium carbonate products with uniform particle size and good spherical shape is achieved, the introduction of impurities is avoided, and the purity and performance of the product are improved.
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Figure CN119898809A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of cerium carbonate preparation, and in particular to small-particle spherical cerium carbonate and a preparation method thereof. Background Art
[0002] Rare earth elements are non-renewable resources. Among the many rare earth elements, cerium has the most abundant reserves and is widely used in a wide range of applications. Among them, cerium dioxide as a polishing powder has the advantages of high polishing accuracy, good finish, small usage, long life and easy cleaning. The closer the cerium dioxide particles are to spherical, the better it is for avoiding defects and surface flatness when used for polishing. The cerium dioxide products prepared by the traditional ball milling dispersion method have low purity and uneven particle size. Literature research shows that cerium oxide can be made from cerium carbonate as a precursor, and cerium carbonate can be further calcined at high temperature to obtain cerium dioxide powder, and its crystal morphology indicators such as morphology and particle size can inherit the cerium carbonate precursor. Therefore, it is of great significance to explore a preparation method for cerium carbonate with a small particle size and controllable spherical morphology to control the morphology of cerium dioxide and increase the added value of cerium.
[0003] The current preparation methods of cerium carbonate include liquid phase precipitation method and hydrothermal method. Liquid phase precipitation method is a commonly used method for preparing cerium carbonate. It controls the reaction conditions in the solution so that cerium ions react with carbonate ions to form cerium carbonate precipitates. However, when preparing small particles of cerium carbonate, this method often leads to uneven distribution of particle sizes and difficulty in obtaining ideal sphericity due to the difficulty in accurately controlling the nucleation and crystal growth processes. Specifically, in the crystallization process of cerium carbonate prepared by liquid phase precipitation method, when the reaction crystallization temperature is low, the cerium carbonate particle size is large and the particle size is uneven. When the reaction crystallization temperature is high, the cerium carbonate product has problems such as irregular morphology and agglomeration. In addition, the liquid phase precipitation method may also introduce impurities, affecting the purity and performance of the product.
[0004] The hydrothermal method is another method for preparing cerium carbonate, which uses a high temperature and high pressure aqueous solution environment to promote the reaction between cerium ions and carbonate ions. Compared with the liquid phase precipitation method, the hydrothermal method can control the particle size to a certain extent and provide a favorable environment of high temperature and high pressure for the formation of spherical cerium carbonate small particles. However, improper operating conditions such as temperature during the hydrothermal process will also cause different crystal morphologies.
[0005] Therefore, it is desirable to prepare small-sized spherical cerium carbonate with controllable morphology by a simple method.
[0006] In order to solve the above problems, the present invention is proposed. Summary of the invention
[0007] The present invention aims to overcome the shortcomings of the prior art. The preparation method of the present invention is not only simple to operate and low in cost, but also can prepare a cerium carbonate product with uniform particle size and good sphericity. The present invention successfully obtains a cerium carbonate with a spherical morphology and a particle median diameter of 1.98-3.65 μm by adjusting the influence of factors such as hydrothermal reaction crystallization temperature, reaction crystallization time, reactant concentration and molar ratio on the cerium carbonate crystal morphology.
[0008] The present invention adopts the following technical solutions:
[0009] The first aspect of the present invention provides a small particle spherical cerium carbonate, wherein the median diameter D of the small particle spherical cerium carbonate is 0.5 The particle size distribution PDI is 1.98-3.65 μm, the particle size distribution PDI is 0.77-1.11, and the sphericity S of the small particle spherical cerium carbonate is 0.91-0.96. Wherein, PDI is the particle size distribution; S represents the sphericity, S=d / a, d is the surface area of a sphere of the same volume as the object, and a is the actual surface area of the object.
[0010] The second aspect of the present invention provides a method for preparing the small-particle spherical cerium carbonate described in the first aspect of the present invention, using a hydrothermal method, cerium nitrate (Ce(NO3)3·6H2O) and urea (CO(NH2)2) as reactants, and adjusting the reaction crystallization temperature, reaction crystallization time, reactant concentration and molar ratio parameters during the reaction process to prepare small-particle spherical cerium carbonate.
[0011] Preferably, the preparation method comprises the following steps:
[0012] (1) Prepare a mixed solution of Ce(NO3)3·6H2O and CO(NH2)2 of a certain concentration;
[0013] (2) subjecting the prepared mixed solution to magnetic stirring, placing the mixed solution into a polytetrafluoroethylene liner after stirring, and then placing it into a stainless steel reactor and sealing it;
[0014] (3) After a certain reaction temperature and a certain reaction crystallization time, the reaction kettle is opened after naturally cooling to room temperature, and vacuum filtration, washing, and drying are performed to obtain the small particles of spherical cerium carbonate, and the morphology and particle size analysis of the crystals is performed.
[0015] Preferably, in step (1), the concentration of Ce(NO3)3·6H2O solution is 0.02-0.06 mol / L; the concentration of CO(NH2)2 solution is 0.06-0.2 mol / L.
[0016] Preferably, in step (1), the molar ratio of Ce(NO3)3·6H2O to CO(NH2)2 is 1:3-1:10.
[0017] Preferably, in step (1), the reaction crystallization temperature is 100-200° C.; and the reaction crystallization time is 2-4 h.
[0018] Preferably, in step (2), the product is washed with deionized water and anhydrous ethanol, and dried in a vacuum drying oven at a drying temperature of 40° C. and a drying time of 6 hours.
[0019] Preferably, in step (1), the volume of the mixed solution of Ce(NO3)3·6H2O and CO(NH2)2 is 50 mL, and in step (2), it is placed in a 100 mL polytetrafluoroethylene liner.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] 1. The present invention successfully obtains a spherical morphology with a particle median diameter of 1.5 mm by adjusting the influence of factors such as hydrothermal reaction crystallization temperature, reaction crystallization time, reactant concentration and molar ratio on the morphology of cerium carbonate crystals.
[0022] Small spherical cerium carbonate particles with a particle size distribution of 1.98-3.65 μm, a particle size distribution PDI of 0.77-1.11, and a sphericity S of 0.91-0.96.
[0023] 2. The present invention finds that factors such as the hydrothermal reaction crystallization temperature, reaction crystallization time, reactant concentration and molar ratio in the hydrothermal crystallization process have a great influence on the morphology of cerium carbonate crystals. By adjusting the above factors, cerium carbonate crystals in the form of spherical, fusiform rods, a mixture of spherical and fusiform rods, and a mixture of spherical and dodecahedral microrods can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a scanning electron microscope (SEM) image of the cerium carbonate product obtained in Example 1.
[0025] Figure 2 This is a scanning electron microscope (SEM) image of the cerium carbonate product obtained in Example 2.
[0026] Figure 3 This is a scanning electron microscope (SEM) image of the cerium carbonate product obtained in Example 3.
[0027] Figure 4 This is a scanning electron microscope (SEM) image of the cerium carbonate product obtained in Example 4.
[0028] Figure 5 This is a scanning electron microscope (SEM) image of the cerium carbonate product obtained in Example 5.
[0029] Figure 6 This is a scanning electron microscope (SEM) image of the cerium carbonate product obtained in Example 6.
[0030] Figure 7This is a scanning electron microscope (SEM) image of the cerium carbonate product obtained in Example 7. DETAILED DESCRIPTION
[0031] The present invention is further described below by way of examples, which are not limited to the examples. Experimental methods without specific conditions specified in the examples are generally carried out under conventional conditions and conditions described in the manual, or under conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used are all commercially available unless otherwise specified.
[0032] The specific steps of the method of the present invention are as follows:
[0033] Example 1
[0034] The concentration of Ce(NO3)3·6H2O was controlled to be 0.02 mol / L, the concentration of CO(NH2)2 was controlled to be 0.06 mol / L, the molar ratio of the reactants was 1:3, the total volume of the reaction solution was 50 mL, the reaction temperature was 160 °C, the reaction crystallization time was 4 h, and the median diameter D was obtained after vacuum filtration, washing and drying (drying temperature was 40 °C, drying time was 6 h). 0.5 The cerium carbonate crystals have a spherical shape and a diameter of 3.64 μm, a PDI of 0.95, a sphericity S of 0.96. Figure 1 shown.
[0035] Example 2
[0036] The concentration of Ce(NO3)3·6H2O was controlled to be 0.02 mol / L, the concentration of CO(NH2)2 was controlled to be 0.06 mol / L, the molar ratio of the reactants was 1:3, the total volume of the reaction solution was 50 mL, the reaction temperature was 180 °C, the reaction crystallization time was 4 h, and the median diameter D was obtained after vacuum filtration, washing and drying (drying temperature was 40 °C, drying time was 6 h). 0.5 The cerium carbonate crystals have a spherical shape and a diameter of 3.65 μm, a PDI of 0.77, a sphericity S of 0.93, and a quasi-spherical crystal morphology. Figure 2 shown.
[0037] Example 3
[0038] The concentration of Ce(NO3)3·6H2O was controlled to be 0.02 mol / L, the concentration of CO(NH2)2 was controlled to be 0.06 mol / L, the molar ratio of the reactants was 1:3, the total volume of the reaction solution was 50 mL, the reaction temperature was 100 °C, the reaction crystallization time was 4 h, and the median diameter D was obtained after vacuum filtration, washing and drying (drying temperature was 40 °C, drying time was 6 h). 0.5 The cerium carbonate crystals have a diameter of 5.71 μm, a PDI of 0.66, a sphericity S of 0.53, and two crystal shapes: quasi-spherical and spindle-shaped (mainly spindle-shaped). Figure 3 shown.
[0039] Example 4
[0040] The concentration of Ce(NO3)3·6H2O was controlled to be 0.02 mol / L, the concentration of CO(NH2)2 was controlled to be 0.06 mol / L, the molar ratio of the reactants was 1:3, the total volume of the reaction solution was 50 mL, the reaction temperature was 160 °C, the reaction crystallization time was 2 h, and the median diameter D was obtained after vacuum filtration, washing and drying (drying temperature was 40 °C, drying time was 6 h). 0.5 The cerium carbonate crystals have a spherical shape and a diameter of 1.98 μm, a PDI of 1.11, a sphericity S of 0.91, and a quasi-spherical crystal morphology. Figure 4 shown.
[0041] Example 5
[0042] The concentration of Ce(NO3)3·6H2O was controlled to be 0.02 mol / L, the concentration of CO(NH2)2 was controlled to be 0.12 mol / L, the molar ratio of the reactants was 1:6, the total volume of the reaction solution was 50 mL, the reaction temperature was 160°C, the reaction crystallization time was 4 h, and the median diameter D was obtained after vacuum filtration, washing and drying (drying temperature was 40°C, drying time was 6 h). 0.5 The crystal has a diameter of 4.48 μm, a PDI of 0.79, a sphericity S of 0.51, and is a mixed crystal of spherical and dodecahedral microrods. Figure 5 shown.
[0043] Example 6
[0044] The concentration of Ce(NO3)3·6H2O was controlled to be 0.02mol / L, the concentration of CO(NH2)2 was 0.2mol / L, the molar ratio of the reactants was 1:10, the total volume of the reaction solution was 50mL, the reaction temperature was 160℃, the reaction crystallization time was 4h, and the median diameter D was obtained after vacuum filtration, washing and drying (drying temperature was 40℃, drying time was 6h). 0.5 The crystal size is 5.07 μm, PDI is 1.36, sphericity S is 0.42, and it is a spindle-shaped rod-shaped crystal. Figure 6 shown.
[0045] Example 7
[0046] The concentration of Ce(NO3)3·6H2O was controlled to be 0.06 mol / L, the concentration of CO(NH2)2 was controlled to be 0.18 mol / L, the molar ratio of the reactants was 1:3, the total volume of the reaction solution was 50 mL, the reaction temperature was 160 °C, the reaction crystallization time was 4 h, and the median diameter D was obtained after vacuum filtration, washing and drying (drying temperature was 40 °C, drying time was 6 h). 0.5 The cerium carbonate crystals have a diameter of 4.5 μm, a PDI of 0.66, a sphericity S of 0.62, and two crystal forms: spherical and dodecahedral microrods. Figure 7 shown.
[0047] Table 1 Crystal morphology and median diameter D in each example 0.5、 Particle size distribution PDI, sphericity comparison
[0048]
[0049] By comparing Example 1 with Example 2 and Example 3, it can be seen that the reaction temperature affects the crystal morphology of the product, wherein when the temperature is 160-180°C, the product is in a spherical crystal morphology.
[0050] By comparing Example 1 and Example 4, it can be seen that the reaction crystallization time affects the crystal morphology of the product, wherein the longer the crystallization time, the smaller the median diameter D 0.5 And the higher the value of sphericity S.
[0051] By comparing Example 1 with Example 5 and Example 6, it can be seen that the molar ratio of reactants affects the crystal morphology of the product, wherein a decrease in the molar ratio of Ce(NO3)3·6H2O to CO(NH2)2 reactants will lead to a change in the crystal morphology of the product. When the molar ratio of Ce(NO3)3·6H2O to CO(NH2)2 reactants is 1:3, the cerium carbonate crystal product is a spherical crystal morphology; and when the molar ratio of Ce(NO3)3·6H2O to CO(NH2)2 reactants is 1:6, the product is a mixed crystal of spherical and dodecahedral microrods; when the molar ratio of Ce(NO3)3·6H2O to CO(NH2)2 reactants is 1:10, the cerium carbonate crystal product has completely turned into a spindle-shaped crystal.
[0052] By comparing Example 1 and Example 7, it can be seen that the concentration of the reactants affects the crystal morphology of the product. As the concentration of Ce(NO3)3·6H2O and CO(NH2)2 increases, the sphericity of the product decreases, and the crystal morphology changes from a quasi-spherical crystal morphology to two crystal morphologies: a quasi-spherical crystal morphology and a dodecahedral microrod body.
[0053] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.
Claims
1. A small particle spherical cerium carbonate, characterized in that: The median diameter D of the small spherical cerium carbonate particles 0.5 The particle size is 1.98-3.65 μm, the particle size distribution PDI is 0.77-1.11, and the sphericity S of the small particle spherical cerium carbonate is 0.91-0.
96.
2. A method for preparing small-particle spherical cerium carbonate according to claim 1, characterized in that: The hydrothermal method was adopted, with cerium nitrate Ce(NO3)3·6H2O and urea CO(NH2)2 as reactants, and small spherical cerium carbonate particles were prepared by regulating the reaction crystallization temperature, reaction crystallization time, reactant concentration and molar ratio parameters during the reaction process.
3. The preparation method according to claim 2, characterized in that: It includes the following steps: (1) Prepare a mixed solution of Ce(NO3)3·6H2O and CO(NH2)2 of a certain concentration; (2) The prepared mixed solution is subjected to magnetic stirring, and after stirring, the mixed solution is placed in a polytetrafluoroethylene liner, and then placed in a stainless steel reactor and sealed; (3) After a certain reaction temperature and a certain reaction crystallization time, the reaction kettle is opened after naturally cooling to room temperature, and vacuum filtration, washing, and drying are performed to obtain the small particles of spherical cerium carbonate, and the morphology and particle size analysis of the crystals is performed.
4. The preparation method according to claim 2, characterized in that: In step (1), the concentration of Ce(NO3)3·6H2O solution is 0.02-0.06 mol / L; the concentration of CO(NH2)2 solution is 0.06-0.2 mol / L.
5. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of Ce(NO3)3·6H2O to CO(NH2)2 is 1:3-1:
10.
6. The preparation method according to claim 2, characterized in that: In step (1), the reaction crystallization temperature is 100-200° C.; and the reaction crystallization time is 2-4 hours.
7. The preparation method according to claim 2, characterized in that: In step (2), the product is washed with deionized water and anhydrous ethanol, and dried in a vacuum drying oven at a drying temperature of 40° C. and a drying time of 6 h.
8. The preparation method according to claim 2, characterized in that: In step (1), the volume of the mixed solution of Ce(NO3)3·6H2O and CO(NH2)2 is 50 mL, and in step (2), it is placed in a 100 mL polytetrafluoroethylene liner.