A method for low-temperature synthesis of ceria
By using Ce(NO3)3·6H2O and C2H10N6H2CO3 to synthesize cerium dioxide at room temperature, the problems of complex raw materials, low safety and high energy consumption in the existing technology have been solved, and the synthesis of cerium dioxide at low temperature, low pollution and high purity has been realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LESHAN NORMAL UNIV
- Filing Date
- 2023-11-29
- Publication Date
- 2026-05-12
AI Technical Summary
Existing methods for synthesizing cerium dioxide suffer from problems such as complex raw materials, low safety, cumbersome processes, and high energy consumption.
Using Ce(NO3)3·6H2O as the cerium source and C2H10N6H2CO3 as the precipitant, cerium dioxide was synthesized at room temperature through stirring and drying processes, avoiding the use of oxidizing agents. The oxidizing compound formed by C2H10N6H2CO3 was used to promote the conversion of Ce3+ to Ce(OH)4.
The low-temperature synthesis of cerium dioxide has been achieved, reducing energy consumption, improving safety and purity, reducing pollution, and making it suitable for industrial production.
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Figure CN117566782B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of cerium dioxide synthesis technology, specifically relating to a method for low-temperature synthesis of cerium dioxide. Background Technology
[0002] Cerium dioxide (CeO2) is abundant, inexpensive, has a unique crystal structure, and exhibits reversible cerium reactivity. 3+ With Ce 4+ The conversion between these two processes has attracted much attention in many fields. Nanoscale CeO2 exhibits unique physicochemical properties due to surface effects, volume effects, quantum size effects, and macroscopic tunneling effects, and has been widely used in precision ceramics, magnetic recording, ultraviolet shielding, photoelectric sensing, and catalysis. Especially in catalysis, nanoscale CeO2, due to its excellent redox capabilities, has significant application value in CO catalytic oxidation, organic synthesis catalysis, photocatalysis, adsorption, and biological antioxidant processes. The synthesis method of CeO2 not only affects its morphology and size but also its application characteristics.
[0003] Currently, the synthesis of CeO2 mainly requires three types of reagents: first, a cerium source, mostly cerium nitrate or cerium chloride (both in the +3 oxidation state); second, a precipitant, used to precipitate CeO2 in aqueous solution. 3+ The precipitation / crystallization of ions mainly involves potassium hydroxide and sodium hydroxide (strong bases), ammonia, urea, ammonium carbonate, and ammonium bicarbonate (weak bases); thirdly, oxidizing agents are used to achieve Ce. 3+ Phase-to-Ce 4+ The phase transformation is mostly in the form of hydrogen peroxide (H2O2). For precipitants, strong bases are highly corrosive, while weak bases are easily volatile; for oxidants, H2O2 is a Class 5 oxidant and a Class 8 corrosive, belonging to the category of explosive strong oxidants, and is highly volatile, posing significant hazards to the skin and respiratory tract. Furthermore, some synthesis processes require high-temperature calcination to obtain the CeO2 phase, undoubtedly further increasing energy consumption. Summary of the Invention
[0004] The problem this invention aims to solve is to provide a method for low-temperature synthesis of cerium dioxide, thereby addressing the issues of complex raw materials, low safety, cumbersome processes, and high energy consumption in the cerium dioxide synthesis process.
[0005] The technical solution adopted to solve the technical problem is to provide a method for low-temperature synthesis of cerium dioxide, including the following steps:
[0006] (1) At room temperature, dissolve Ce(NO3)3·6H2O in a solvent, then add C2H 10 N6H2CO3, stirred, to obtain precursor 1;
[0007] (2) Centrifuge precursor 1, collect the precipitate and wash it to obtain precursor 2;
[0008] (3) Dry the precursor 2 at 115-130℃ for 24-26 hours to obtain cerium dioxide.
[0009] The beneficial effects of the above technical solution in this invention are as follows: using Ce(NO3)3·6H2O as the cerium source, C2H 10 N6H2CO3 was used as a precipitant to remove Ce from aqueous solution. 3+ Crystallization occurs; simultaneously, C2H... 10 N6H2CO3, as a guanidine compound, can form hydrogen-bonded complexes with various oxocations and can also act as an acceptor for oxoanion guests. During the reaction, through continuous stirring, water molecules are subjected to hydrodynamic forces, generating an electrostatic effect that excites oxygen molecules in the air, forming oxoanions. These oxoanions can then activate oxygen molecules in the air, and further enhance the reaction between Ce(NO3)3·6H2O and C2H... 10 During the reaction of N6H2CO3, C2H 10 N6H2CO3 and NO 3- Complexation forms oxidizing compounds, promoting Ce 3+ The transformation to Ce(OH)4, followed by drying, results in the more complete formation of cerium dioxide from Ce(OH)4.
[0010] Preferably, in step (1), Ce(NO3)3·6H2O and C2H 10 The mass ratio of N6H2CO3 to water is 1:(1.7~2):15; the solvent is distilled water.
[0011] Preferably, the stirring time in step (1) is 22 to 26.5 hours.
[0012] More preferably, the stirring in step (1) includes the following steps: first stirring for 15 minutes until the color of the system changes, and then continuing to stir for 24 hours.
[0013] Preferably, in step (2), the centrifugation speed is 4000-5000 rpm and the centrifugation time is 8-12 min; the washing is performed by washing with distilled water 3-5 times.
[0014] Preferably, in step (2), the centrifugation speed is 4500 rpm and the centrifugation time is 10 min; the washing is done by washing with distilled water 3 times.
[0015] Preferably, the drying temperature in step (3) is 120°C and the drying time is 24 hours.
[0016] The present invention also provides cerium dioxide synthesized by the above method.
[0017] The present invention has the following beneficial effects:
[0018] (1) This invention uses C2H 10 N6H2CO3, as a precipitant, requires no additional oxidant or other reaction aids. The reaction process is gentle, does not produce a large amount of gas, has low volatility, and generates less pollution.
[0019] (2) The raw materials of the present invention are readily available and have low cost. The prepared cerium dioxide has high purity and no impurities.
[0020] (3) The synthesis process of this invention has a low temperature and can be carried out at room temperature and pressure. It does not require high-temperature calcination or other processes. Cerium dioxide can be obtained by drying. It has low energy consumption and is easy to achieve industrial production. Attached Figure Description
[0021] Figure 1 This is the XRD pattern of cerium dioxide synthesized in Example 1;
[0022] Figure 2 This is the XRD pattern of cerium dioxide synthesized in Example 2;
[0023] Figure 3 This is the XRD pattern of cerium dioxide synthesized in Example 3;
[0024] Figure 4 The XRD pattern of the sample synthesized in Comparative Example 1 is shown below.
[0025] Figure 5 The XRD pattern of the sample synthesized in Comparative Example 2 is shown below.
[0026] Figure 6 The XRD pattern of the sample synthesized in Comparative Example 3 is shown below.
[0027] Figure 7 The XRD pattern of the sample synthesized in Comparative Example 4 is shown.
[0028] Figure 8 The XRD pattern of the sample synthesized in Comparative Example 5 is shown below.
[0029] Figure 9 This is the XRD pattern of the sample synthesized in Comparative Example 6. Detailed Implementation
[0030] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0031] Example 1
[0032] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0033] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 1.7g of C2H 10 N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 15 minutes, a pale yellow emulsion is obtained. After stirring continuously for 24 hours, precursor 1 is obtained.
[0034] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0035] (3) Transfer the precursor 2 to a 30 mL crucible and dry it at 130 °C for 24 h to obtain a light yellow solid powder, namely cerium dioxide.
[0036] This embodiment also includes cerium dioxide prepared by the above method.
[0037] Example 2
[0038] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0039] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 1.9g of C2H 10 N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 15 minutes, a pale yellow emulsion is obtained. After stirring continuously for 24 hours, precursor 1 is obtained.
[0040] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0041] (3) Transfer the precursor 2 to a 30 mL crucible and dry it at 120 °C for 24 h to obtain a light yellow solid powder, namely cerium dioxide.
[0042] This embodiment also includes cerium dioxide prepared by the above method.
[0043] Example 3
[0044] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0045] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 2g of C2H 10 N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 15 minutes, a pale yellow emulsion is obtained. After stirring continuously for 24 hours, precursor 1 is obtained.
[0046] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0047] (3) Transfer the precursor 2 to a 30 mL crucible and dry it at 115 °C for 24 h to obtain a light yellow solid powder, namely cerium dioxide.
[0048] This embodiment also includes cerium dioxide prepared by the above method.
[0049] Example 4
[0050] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0051] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 1.7g of C2H 10 N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 13 minutes, a pale yellow emulsion is obtained. After stirring continuously for 22 hours, precursor 1 is obtained.
[0052] (2) Centrifuge precursor 1 at 4000 rpm for 12 min, take the precipitate and wash it 4 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0053] (3) Transfer the precursor 2 to a 30 mL crucible and dry it at 130 °C for 24 h to obtain a light yellow solid powder, namely cerium dioxide.
[0054] This embodiment also includes cerium dioxide prepared by the above method.
[0055] Example 5
[0056] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0057] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 1.7g of C2H 10 N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 17 minutes, a pale yellow emulsion is obtained. After stirring continuously for 26 hours, precursor 1 is obtained.
[0058] (2) Centrifuge precursor 1 at 5000 rpm for 8 min, take the precipitate and wash it 5 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0059] (3) Transfer the precursor 2 to a 30 mL crucible and dry it at 130 °C for 24 h to obtain a light yellow solid powder, namely cerium dioxide.
[0060] This embodiment also includes cerium dioxide prepared by the above method.
[0061] Comparative Example 1
[0062] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0063] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 1.7g of C2H 10 N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 15 minutes, a pale yellow emulsion is obtained. After stirring continuously for 24 hours, precursor 1 is obtained.
[0064] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0065] (3) Transfer precursor 2 to a 30 mL crucible and dry at 100 °C for 24 h to obtain the sample.
[0066] This comparative example also includes samples prepared by the above method.
[0067] Comparative Example 2
[0068] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0069] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 1.4g of C2H 10 N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 15 minutes, a pale yellow emulsion is obtained. After stirring continuously for 24 hours, precursor 1 is obtained.
[0070] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0071] (3) Transfer precursor 2 to a 30 mL crucible and dry at 130 °C for 24 h to obtain the sample.
[0072] This comparative example also includes samples prepared by the above method.
[0073] Comparative Example 3
[0074] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0075] (1) At room temperature, dissolve 1g of Ce(NO3)3·6H2O in 15g of distilled water, then add 1.9g of C2H 10N6H2CO3 immediately produces a milky white emulsion. After stirring continuously for 15 minutes, a pale yellow emulsion is obtained. After stirring continuously for 24 hours, precursor 1 is obtained.
[0076] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0077] (3) Transfer precursor 2 to a 30 mL crucible and dry at 100 °C for 24 h to obtain the sample.
[0078] This comparative example also includes samples prepared by the above method.
[0079] Comparative Example 4
[0080] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0081] (1) At room temperature, dissolve 1g of CeCl3 in 15g of distilled water, then add 1.9g of C2H 10 N6H2CO3 immediately produces a pale yellow emulsion. After stirring continuously for 15 minutes, there is no obvious change. After stirring continuously for another 24 hours, precursor 1 is obtained.
[0082] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0083] (3) Transfer precursor 2 to a 30 mL crucible and dry at 120 °C for 24 h to obtain the sample.
[0084] This comparative example also includes samples prepared by the above method.
[0085] Comparative Example 5
[0086] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0087] (1) At room temperature, 1g of Ce(NO3)3·6H2O was dissolved in 15g of distilled water, and then 1g of (NH4)2CO3 was added. Immediately, a milky white emulsion was generated and bubbles were produced. After stirring for 15min, a milky white emulsion was obtained. After stirring for 24h, precursor 1 was obtained.
[0088] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0089] (3) Transfer precursor 2 to a 30 mL crucible and dry at 120 °C for 24 h to obtain the sample.
[0090] This comparative example also includes samples prepared by the above method.
[0091] Comparative Example 6
[0092] A method for low-temperature synthesis of cerium dioxide includes the following steps:
[0093] (1) At room temperature, 1g of Ce(NO3)3·6H2O was dissolved in 15g of distilled water, and then 0.8g of NH4HCO3 was added. Immediately, a milky white emulsion was generated and a large number of bubbles were produced. After stirring for 15min, a milky white emulsion was obtained. After stirring for 24h, precursor 1 was obtained.
[0094] (2) Centrifuge precursor 1 at 4500 rpm for 10 min, take the precipitate and wash it 3 times with distilled water, collect the solid precipitate, and obtain precursor 2.
[0095] (3) Transfer precursor 2 to a 30 mL crucible and dry at 120 °C for 24 h to obtain the sample.
[0096] This comparative example also includes samples prepared by the above method.
[0097] Experimental Example
[0098] XRD patterns of cerium dioxide synthesized in Examples 1-3 and samples synthesized in Comparative Examples 1-6 were analyzed, and the results are as follows: Figures 1-9 As shown.
[0099] Depend on Figures 1-3 It can be seen that the cerium dioxide synthesized by the low-temperature synthesis method in Examples 1 to 3 is pure and free of impurities.
[0100] Depend on Figure 4 and Figure 6 It can be seen that when the drying temperature is below 115℃, the Ce in Ce(NO3)3·6H2O 3+ Ce forms as Ce(OH)4 4+ It cannot be completely converted into cerium dioxide, and the resulting sample contains a lot of impurities, resulting in low purity of cerium dioxide.
[0101] Depend on Figure 5 It can be seen that when C2H 10 When the N6H2CO3 content is too low, Ce will be present during the reaction. 3+ It cannot transform into Ce(OH)4. Even when the drying temperature is above 115℃, the dried sample contains many impurities and cannot form pure cerium dioxide.
[0102] Depend on Figure 7It is known that when CeCl3 is used as the cerium source, pure cerium dioxide cannot be obtained, and other impurities are present in the resulting sample. This is because, under the condition of using CeCl3 as the cerium source, the reaction can only use oxygen captured from the air as an oxidant, which is insufficient. Therefore, pure cerium dioxide cannot be synthesized under the condition of a drying temperature of 120℃.
[0103] Depend on Figures 8-9 It can be seen that replacing C2H with (NH4)2CO3 or NH4HCO3... 10 N6H2CO3 cannot produce cerium dioxide. This is because amines have low pKa values, requiring strong acid solutions for sufficient protonation and effective binding with anions; while guanidines have high pKa values (13.5) and maintain positive charge over a wide pH range, allowing them to react with NO in Ce(NO3)3·6H2O under alkaline conditions. 3- Complexation forms substances with certain oxidizing properties.
[0104] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the scope of the present invention.
Claims
1. A method for low-temperature synthesis of cerium dioxide, characterized in that, Includes the following steps: (1) At room temperature, dissolve Ce(NO3)3·6H2O in a solvent, then add C2H 10 N6H2CO3, stirred, to obtain precursor 1; (2) Centrifuge precursor 1, collect the precipitate and wash it to obtain precursor 2; (3) Dry the precursor 2 at 115~130℃ for 24~26h to obtain cerium dioxide; In step (1), Ce(NO3)3·6H2O and C2H 10 The mass ratio of N6H2CO3 to water is 1:(1.7~2):15; the solvent is distilled water.
2. The method for low-temperature synthesis of cerium dioxide as described in claim 1, characterized in that: The stirring time in step (1) is 22~26.5h.
3. The method for low-temperature synthesis of cerium dioxide as described in claim 2, characterized in that, The stirring in step (1) includes the following steps: first stir for 15 minutes until the color of the system changes, and then continue stirring for 24 hours.
4. The method for low-temperature synthesis of cerium dioxide as described in claim 1, characterized in that: In step (2), the centrifugation speed is 4000~5000 rpm and the centrifugation time is 8~12 min; the washing is washing with distilled water 3~5 times.
5. The method for low-temperature synthesis of cerium dioxide as described in claim 4, characterized in that: In step (2), the centrifugation speed is 4500 rpm and the centrifugation time is 10 min; the washing is washing with distilled water 3 times.
6. The method for low-temperature synthesis of cerium dioxide as described in claim 1, characterized in that: In step (3), the drying temperature is 120℃ and the drying time is 24h.
7. Cerium dioxide synthesized by the method for low-temperature synthesis of cerium dioxide according to any one of claims 1 to 6.