Preparation system and method of nano cerium oxide and high-dispersity nano cerium oxide

Abstract

The invention belongs to the technical field of preparation of rare earth nano materials, and particularly discloses a preparation system and method of nano cerium oxide and high-dispersity nano cerium oxide. The preparation system comprises an organic complexing agent and a surface modifier; the organic complexing agent is at least one of polyaspartic acid and derivatives thereof, polyglutamic acid, ethylenediamine disuccinic acid, iminodiacetic acid and sodium alginate; the surface modifier is a silane coupling agent. The preparation method comprises the following steps: preparing a cerium source precursor solution; adding an organic complexing agent and a surface modifier; regulating and controlling the pH value; and washing, aging, drying, grinding and calcining. The nano cerium oxide is prepared by the method. According to the invention, the organic complexing agent is combined with in-situ surface modification, and the complexing mechanism and the preparation process are optimized, so that high dispersity, uniform particle size distribution and controllable synthesis of the nano cerium oxide particles are realized, meanwhile, the harm of the process to the environment is reduced, and the operation process is simplified so as to adapt to industrial production requirements.

Description

Technical Field

[0001] This invention belongs to the field of rare earth nanomaterial preparation technology, specifically a nano-cerium oxide preparation system and method, and highly dispersed nano-cerium oxide. Background Technology

[0002] Nano-cerium oxide (CeO2), as an important rare earth oxide, is valued for its unique oxygen vacancy defects and CeO2 content. 3+ / Ce 4+ The reversible conversion properties of cerium oxide nanoparticles have wide applications in catalysis, energy storage, biomedicine, and environmental remediation. The performance of cerium oxide nanoparticles is closely related to their particle size, morphology, and dispersibility; therefore, developing methods for the controllable preparation of cerium oxide nanoparticles is of great significance.

[0003] Currently, the main methods for preparing nano-cerium oxide include precipitation, hydrothermal methods, microemulsion methods, and sol-gel methods. Among these, the sol-gel method has attracted widespread attention due to its advantages such as simple process, high product purity, and controllable particle size. However, nano-cerium oxide prepared by the traditional sol-gel method is prone to agglomeration, resulting in uneven particle size distribution and affecting its application performance. Subsequent surface modification steps are usually required to improve its dispersibility and functional properties.

[0004] In the prior art, CN114477264A discloses a sol-gel method for preparing nano-cerium oxide, using organic amines (such as triethanolamine) as complexing agents, which has achieved certain results, but still has the following shortcomings: (1) large amount of organic precipitant is used, resulting in high cost; (2) high calcination temperature (650-750℃), resulting in high energy consumption; (3) insufficient precision in particle size control. Therefore, developing a method that combines environmentally friendly and efficient complexing agents with in-situ surface modifiers to improve the preparation process and product performance of nano-cerium oxide has important research significance and application value. Summary of the Invention

[0005] The purpose of this invention is to provide a preparation system for nano-cerium oxide, which combines organic complexation with in-situ surface modification. By optimizing the complexation mechanism and preparation process, the system achieves high dispersibility, uniform particle size distribution, and controllable synthesis of nano-cerium oxide particles, while reducing the environmental impact of the process and simplifying the operation process to meet the needs of industrial production.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A preparation system for nano-cerium oxide includes an organic complexing agent and a surface modifier;

[0008] The organic complexing agent is at least one of polyaspartic acid and its derivatives, polyglutamic acid, ethylenediamine disuccinic acid, iminodiacetic acid, and sodium alginate.

[0009] The surface modifier is a silane coupling agent.

[0010] Preferably, the amount of the organic complexing agent added is equal to the Ce content in the system. 3+ 40% to 120% of the quality.

[0011] Preferably, the surface modifier reacts with Ce in the system. 3+ The molar ratio is 0.05:1 to 0.3:1.

[0012] Preferably, it also includes an acidic pH adjuster and an alkaline pH adjuster.

[0013] Preferably, the acidic pH adjuster adjusts the pH of the system to 4.5-5.5; the alkaline pH adjuster adjusts the pH of the system to 9-10.

[0014] Another object of the present invention is to provide a method for preparing nano-cerium oxide, comprising the following steps:

[0015] S1: Preparation of cerium source precursor solution;

[0016] S2: Add an organic complexing agent and a surface modifier to the precursor solution and mix thoroughly to form a viscous solution mixture system;

[0017] S3: First, add an acidic pH adjuster to the mixed system to carry out the first step of the reaction; then add an alkaline pH adjuster to carry out the second step of the reaction.

[0018] S4: Wash, age, dry, grind, and calcinate to obtain the product.

[0019] Preferably, in step S1, the method for preparing the precursor solution includes: dissolving a cerium source in an ethanol / water mixed solvent and stirring until a transparent and homogeneous precursor solution is formed.

[0020] Preferably, the volume ratio of ethanol to water is 1:1 to 1:2.

[0021] Preferably, in step S1, the cerium source is at least one of cerium nitrate, cerium acetate, cerium chloride, and cerium sulfate.

[0022] Preferably, magnetic stirring is used, with a rotation speed of 300-500 r / min and a stirring time of 5-10 min.

[0023] Preferably, in step S2, a pH indicator is added and the mixture is stirred for 15–30 minutes.

[0024] This invention employs a two-stage pH adjustment, combined with a trace amount of pH indicator (phenolphthalein), to ensure a stable reaction environment and avoid uneven particle growth caused by localized excessive alkalinity, ultimately obtaining nano-cerium oxide with a particle size of 150–400 nm and uniform distribution.

[0025] Preferably, in step S3, the pH value of the acidic pH adjuster system is adjusted to 4.5-5.5, and stirred at room temperature for 1 hour; the pH value of the alkaline pH adjuster system is adjusted to 9-10, and the viscous solution is stirred in a water bath at 55-65°C to transform into a sol.

[0026] Preferably, the dropping rate of the acidic pH adjuster and the alkaline pH adjuster is 1 to 2 mL / min.

[0027] Preferably, the acidic pH adjuster is at least one of dilute nitric acid, acetic acid, and dilute hydrochloric acid; the alkaline pH adjuster is at least one of ammonium carbonate, ammonia, and ammonium bicarbonate.

[0028] Preferably, in step S4, the aging method includes: microwave treatment at a power of 200-600W for 10-30 minutes, with a gel temperature ≤60℃.

[0029] Preferably, in step S4, the washing process involves washing with ethanol and deionized water 2 to 4 times respectively.

[0030] Preferably, in step S4, the gel is placed in an anhydrous solvent before drying to displace the water in the gel.

[0031] Preferably, in step S4, the drying method is to let it stand for 22 to 26 hours under ventilated conditions.

[0032] Preferably, the anhydrous solvent is anhydrous ethanol and acetone (a low surface tension solvent); the replacement process is as follows: first soak in anhydrous ethanol 1 to 3 times (25 to 35 minutes each time), then soak in acetone 1 to 3 times (25 to 35 minutes each time).

[0033] Preferably, in step S4, the calcination method includes: first, heating to 200-300°C at 2-5°C / min and holding for 1-2 hours to remove organic matter; then heating to 400-600°C at 2-5°C / min and holding for 2-3 hours to complete the formation and growth of the crystal structure.

[0034] The microwave-assisted aging and stepwise calcination technology of this invention (first removing organic matter at low temperature, then crystallizing at high temperature) further shortens the reaction time and improves efficiency, while avoiding abnormal particle growth or sintering.

[0035] A third objective of this invention is to provide highly dispersed nano-cerium oxide, prepared by the above method.

[0036] This invention addresses the problems of nano-cerium oxide agglomeration and uneven particle size distribution through the synergistic effect of organic complexing agents and surface modifiers. The principle is as follows:

[0037] Organic complexing agents utilize steric hindrance to inhibit aggregation. In this invention, a complexing agent similar to Ce is selected. 3+ Organic complexing agents with moderate coordination ability (such as polyaspartic acid) allow the carboxyl side chain of polyaspartic acid (PASP) to bind with Ce. 3+ It forms multidentate coordination, and its main chain conformation extends, generating a stronger steric hindrance effect. Moreover, during the calcination process, the gradual pyrolysis of the organic complexing agent (200-400℃) produces gases (such as CO2, NO2, and H2O). The high-temperature pyrolysis creates buffer spaces, forming temporary air gaps between particles, further preventing particle contact sintering.

[0038] In-situ surface modification utilizes the directional anchoring effect of functional molecules. Added functional molecules, such as 3-aminopropyltriethoxysilane (APTES), interact with Ce in the sol stage via amino groups. 3+ The complexation is hydrolyzed into -Si-O-Ce bonds after calcination. The surface modification layer (such as Si-O-Ce) formed during calcination physically blocks particle contact, allowing hydrophobic groups (-CH2CH3) to uniformly cover the surface.

[0039] The synergistic mechanism of organic complexing agents and surface modifiers can improve particle size uniformity and dispersion performance. This synergistic mechanism achieves precise time-series control through two-stage pH regulation:

[0040] In the acidic stage (pH = 5 ± 0.5), organic complexing agents preferentially bind to Ce. 3+ Formation of soluble complexes, effectively inhibiting Ce 3+ Rapid hydrolysis avoids explosive nucleation; at the same time, the carboxylic acid groups in the surface modifier assist in complexation, further stabilizing the precursor.

[0041] Under alkaline conditions, the hydroxyl groups on the CeO2 surface deprotonate, and the Ce-O particles on the surface... - Negatively charged, the -NH2 group of the silane coupling agent protonates to -NH3 under alkaline conditions. + Positively charged, -NH3 + With surface Ce-O -An electrostatic-covalent dual anchoring (Si-O-Ce bond + electrostatic adsorption) is formed, fixing positive charges to the particle surface. After anchoring, the entire particle surface is positively charged, and positive-positive electrostatic repulsion occurs between adjacent particles, thus preventing aggregation. Therefore, in the alkaline stage (pH = 9.5 ± 0.5), the siloxane groups of the surface modifier hydrolyze and anchor, forming strong Ce-O-Si covalent bonds, achieving permanent modification of the particle surface; its protonated amino groups become positively charged, anchoring with the negatively charged colloidal particles, and the anchored particle surface becomes positively charged. Combined with the steric hindrance effect of the organic complexing agent, a dual stabilization mechanism of "electrostatic-steric hindrance" is constructed, significantly enhancing the stability of the sol.

[0042] The synergistic effect of the two forms a three-level network of "coordination-crosslinking-steric hindrance", enabling Ce to 3+ The hydrolysis rate is reduced, the condensation process is more uniform, and the gel network structure is denser and more uniform. During the process, pH is monitored visually using trace amounts of pH indicators (such as phenolphthalein) to prevent uneven particle growth or modification agent failure caused by localized excessive alkalinity.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] 1. Compared with traditional organic amine complexing agents, this invention plays a role in steric hindrance and electrostatic stabilization during particle formation by utilizing the steric hindrance effect of organic complexing agents (such as PASP, PGA, etc.) and the synergistic effect of in-situ surface modifiers (such as silane coupling agents), which significantly inhibits the aggregation of nano-cerium oxide particles and significantly improves particle dispersibility.

[0045] 2. This invention combines the traditional two-step process of sol-gel preparation and surface modification into a single step, simplifying the process flow, reducing equipment requirements, and making it easy to control operating parameters (such as temperature and pH), resulting in good repeatability. It uses non-toxic, biodegradable organic complexing agents (such as PASP and PGA), and the calcination products are only CO2, NO2, and H2O, meeting the requirements of green chemistry. By selecting specific modifying agents, different surface properties can be imparted to nano-cerium oxide, expanding its applications in catalysis, biomedicine, coatings, and other fields. Attached Figure Description

[0046] Figure 1 The XRD pattern of the nano-cerium oxide sample prepared by treatment 1-1 in Example 1;

[0047] Figure 2 SEM image of the nano-cerium oxide sample prepared by treatment 1-1 in Example 1;

[0048] Figure 3 SEM images of the nano-cerium oxide samples prepared by processing 1-2 in Example 1;

[0049] Figure 4SEM images of the nano-cerium oxide samples prepared by processing 1-3 in Example 1;

[0050] Figure 5 SEM images of the nano-cerium oxide samples prepared by processing 1-4 in Example 1;

[0051] Figure 6 SEM images of the nano-cerium oxide samples prepared by processing 1-5 in Example 1;

[0052] Figure 7 SEM images of the nano-cerium oxide samples prepared by processing 1-6 in Example 1;

[0053] Figure 8 SEM images of the nano-cerium oxide samples prepared by processing 1-7 in Example 1;

[0054] Figure 9 SEM images of the nano-cerium oxide samples prepared by processing 1-8 in Example 1;

[0055] Figure 10 SEM images of the nano-cerium oxide samples prepared by processing 1-9 in Example 1;

[0056] Figure 11 SEM image of the nano-cerium oxide sample prepared by treatment 2-2 in Example 2;

[0057] Figure 12 SEM images of the nano-cerium oxide samples prepared by treatments 2-3 in Example 2;

[0058] Figure 13 SEM images of the nano-cerium oxide samples prepared by treatments 2-4 in Example 2;

[0059] Figure 14 The image shows a SEM image of the nano-cerium oxide sample prepared by treatment 3-2 in Example 3. Detailed Implementation

[0060] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0061] In the following examples / comparative examples of the present invention, all raw materials used were commercially available.

[0062] Example 1

[0063] A preparation system for highly dispersed nano-cerium oxide includes an organic complexing agent and a surface modifier, an acidic pH adjuster and an alkaline pH adjuster; the organic complexing agent is at least one selected from polyaspartic acid and its derivatives, polyglutamic acid, ethylenediaminedisuccinic acid, iminodiacetic acid, and sodium alginate; the surface modifier is a silane coupling agent; the amount of the organic complexing agent added is equal to the Ce content in the system. 3+ The mass of the surface modifier is 40% to 120% of that of the Ce in the system. 3+ The molar ratio is 0.05:1 to 0.3:1; the acidic pH adjuster adjusts the pH of the system to 4.5 to 5.5; the alkaline pH adjuster adjusts the pH of the system to 9 to 10; the acidic pH adjuster is at least one of dilute nitric acid, acetic acid, and dilute hydrochloric acid; the alkaline pH adjuster is at least one of ammonium carbonate, ammonia, and ammonium bicarbonate.

[0064] A method for preparing highly dispersed nano-cerium oxide includes the following steps:

[0065] S1: Preparation of cerium source precursor solution: Dissolve the cerium source in an ethanol / water mixed solvent, and use magnetic stirring at a speed of 300-500 r / min for 5-10 min until a transparent and homogeneous precursor solution is formed; the volume ratio of ethanol to water in the mixed solvent is 1:1 to 1:2; the cerium source is at least one of cerium nitrate, cerium acetate, cerium chloride, cerium sulfate, etc.

[0066] S2: Add an organic complexing agent, a surface modifier, and a pH indicator to the precursor solution, stir for 15-30 minutes to mix thoroughly, and form a viscous solution mixture system;

[0067] S3: First, add an acidic pH adjuster to the mixed system to adjust the pH to 4.5–5.5, stir at room temperature for 0.8–1.2 h to carry out the first step reaction; then add an alkaline pH adjuster to adjust the pH to 9–10, continue stirring in a 55–65℃ water bath to carry out the second step reaction, until the viscous solution is converted into a sol; the dropping rate of the acidic and alkaline pH adjusters is 1–2 mL / min;

[0068] S4: Washing, aging, drying, grinding, and calcining are then performed to obtain the product;

[0069] The washing process involves washing with ethanol and deionized water 2 to 4 times respectively; the anhydrous solvent is anhydrous ethanol and acetone (a low surface tension solvent); the replacement process is as follows: first soak in anhydrous ethanol 1 to 3 times (25 to 35 minutes each time), then soak in acetone 1 to 3 times (25 to 35 minutes each time).

[0070] The aging method includes: microwave treatment at a power of 200-600W for 10-30 minutes, with a gel temperature ≤60℃;

[0071] The drying method is as follows: let it stand under ventilation for 22-26 hours; before drying, place the gel in an anhydrous solvent to displace the water in the gel;

[0072] The calcination method includes: first, heating to 200-300℃ at 2-5℃ / min and holding for 1-2 hours to remove organic matter; then heating to 400-600℃ at 2-5℃ / min and holding for 2-3 hours to complete the formation and growth of the crystal structure.

[0073] Referring to the preparation system and method provided above, different treatment groups were set up with the specific components and amounts of organic complexing agents and surface modifiers as variables, as shown in Table 1, to investigate the effect of these variables on the properties of the prepared nano-cerium oxide. The cerium source was cerium nitrate Ce(NO3)3·6H2O (0.01 mol), with an amount of 4.34 g; treatments 1-6 to 1-9 were used as controls.

[0074] Table 1

[0075]

[0076] Example 2

[0077] Referring to the preparation system and method provided in Example 1, and the settings of treatments 1-2, different treatment groups were set up with the pH control of the system as a variable, as shown in Table 2, to investigate the effect of this variable on the properties of the prepared nano-cerium oxide. Among them, treatments 2-2 to 2-4 were used as comparisons.

[0078] Table 2

[0079] Processing group acidic pH adjuster alkaline pH adjuster 2-1 Adjust the pH of the solution to 5 Adjust the pH of the solution to 9.5. 2-2 Adjust the pH of the solution to 5 / 2-3 / Adjust the pH of the solution to 9.5. 2-4 / /

[0080] Example 3

[0081] Referring to the preparation system and method provided in Example 1, as well as the settings of treatment 2-1, different treatment groups were set with the specific calcination method as a variable, as shown in Table 3, to investigate the effect of this variable on the properties of the prepared nano-cerium oxide.

[0082] Table 3

[0083]

[0084] Comparative Example

[0085] Commercially available nano-cerium oxide, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., model number C103980.

[0086] Performance testing experiment

[0087] 1. The cerium oxide products obtained from each treatment group in Examples 1-3 and the samples from the comparative examples were subjected to SEM analysis, such as... Figures 1-14 As shown.

[0088] 2. Determination of Zeta potential and dispersion coefficient: The prepared cerium oxide powder was formulated into a cerium oxide polishing slurry with a mass fraction of 1%, and the Zeta potential and dispersion coefficient were determined using a Bruker (USA) multi-angle particle size and high-sensitivity Zeta potential analyzer.

[0089] 3. Average particle size determination: The obtained cerium oxide powder was prepared into a cerium oxide polishing slurry with a mass fraction of 1%, and the particle size was determined using a Bruker (USA) multi-angle particle size analyzer and a high-sensitivity Zeta potential analyzer.

[0090] 4. Polishing roughness test: The obtained cerium oxide powder was prepared into a cerium oxide polishing slurry with a mass fraction of 1%. The K9 glass was polished using the prepared polishing slurry. After polishing, the surface roughness of the glass was measured using a Bruker (USA) atomic force microscope.

[0091] 5. The measurement results are shown in Table 4.

[0092] Table 4

[0093]

[0094]

[0095] As shown in Table 4 of the test results, treatment 1-2 (polyglutamic acid + 3-aminopropyltriethoxysilane) exhibited the best overall performance. Comparing treatments 1-8 (polyaspartic acid only) and 1-9 (3-aminopropyltriethoxysilane only), it is evident that the performance significantly decreased when either component was used alone, indicating that the synergistic effect of the two is crucial. Furthermore, the use of non-preferred complexing agents or non-preferred surface modifiers led to a decrease in performance (e.g., treatments 1-6 and 1-7).

[0096] Treatment 2-1 (two-stage pH control) showed the best performance, while treatments 2-2 (acidic only), 2-3 (alkaline only), and 2-4 (no control) all exhibited problems such as increased particle size, poor dispersibility, and increased roughness.

[0097] Treatment 3-1 (stepwise calcination) exhibited excellent performance, while treatment 3-2 (one-step high-temperature calcination) failed to form a complete crystal structure. This indicates that stepwise calcination is beneficial for the gradual decomposition of organic matter and the orderly growth of crystals, avoiding sintering and agglomeration. Compared with the comparative example (commercially available product), although its average particle size is smaller, its dispersibility and surface uniformity are not as good as the sample prepared in this invention.

[0098] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A system for the preparation of nanoceria, characterized in that: The organic complexing agent and the surface modifier are included. The organic complexing agent is at least one of polyaspartic acid and its derivatives, polyglutamic acid, ethylenediamine disuccinic acid, iminodiacetic acid, and sodium alginate. The surface modifier is a silane coupling agent.

2. The system for the preparation of nanoceria of claim 1, wherein: The amount of the organic complexing agent added is 40% to 120% of the mass of Ce 3+ in the system.

3. The system for preparing high dispersibility nanoceria of claim 1, wherein: The surface modifier is present in a molar ratio of 0.05:1 to 0.3:1 relative to Ce 3+ in the system.

4. The system for preparing nanoceria of claim 1, wherein: An acidic pH regulator and a basic pH regulator are also included.

5. The system for preparing nanoceria of claim 1, wherein: The acidic pH regulator adjusts the pH value of the system to 4.5-5.5, and the basic pH regulator adjusts the pH value of the system to 9-10.

6. A method for preparing nanometer cerium oxide, characterized in that, The method comprises the following steps: S1: preparing a cerium source precursor solution; S2: adding an organic complexing agent and a surface modifier to the precursor solution, mixing thoroughly to form a mixed system; S3: adding an acidic pH regulator to the mixed system to perform a first step reaction, and then adding a basic pH regulator to perform a second step reaction; S4: washing, aging, drying, grinding, and calcining to obtain the product.

7. The method for preparing nano-cerium oxide as described in claim 6, characterized in that: In step S1, the preparation method of the precursor solution comprises dissolving a cerium source in an ethanol / water mixed solvent and stirring uniformly.

8. The method for preparing nano-cerium oxide as described in claim 6, characterized in that: In step S4, the aging method comprises microwave treatment at a power of 200-600 W for 10-30 min.

9. The method for preparing nano-cerium oxide as described in claim 6, characterized in that: In step S4, the calcining method comprises first increasing the temperature to 200-300 ℃ at a rate of 2-5 ℃ / min, maintaining the temperature for 1-2 h, and then increasing the temperature to 400-600 ℃ at a rate of 2-5 ℃ / min, maintaining the temperature for 2-3 h.

10. A highly dispersible nanoceria, characterized in that, The product is prepared by the method of any one of claims 6-9.

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