Preparation method and application of nano dysprosium oxide particles

Abstract

The present invention discloses a preparation method and application of nano-dysprosium oxide particles, belonging to the technical field of rare earth material preparation. The preparation method comprises the following steps: preparing a dysprosium nitrate solution; adding deionized water to a reactor, heating the temperature to 50-70°C, and adding a surfactant; slowly adding the dysprosium nitrate solution dropwise for 2-3 hours, controlling the temperature to 50-70°C, adding an ammonium carbonate solution dropwise to control the pH of the system to 5.5-7.5, stirring for 1-2 hours after the addition is completed, obtaining a white precipitate, filtering, and washing to obtain a wet product; and roasting, crushing, and sieving the wet product to obtain nano-dysprosium oxide. The present invention avoids the agglomeration of dysprosium oxide particles during the co-precipitation process by using a prepared polymer surfactant, and the prepared nano-dysprosium oxide particles are uniform in size, have a high specific surface area, and have long-term storage stability.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth material preparation, and in particular to a preparation method of nano dysprosium oxide particles and applications thereof. Background Art

[0002] Rare earth oxides are widely used in magnetic materials, catalytic materials, hydrogen storage materials, optical glass, optical fibers, and ceramic capacitors. Dysprosium oxide, with its excellent physical and chemical properties, is used as a raw material for producing metallic dysprosium, as an additive in glass and neodymium iron boron permanent magnets. It is also used in metal halide lamps, magneto-optical memory materials, yttrium iron or yttrium aluminum garnet, and in the atomic energy industry, as control rods for nuclear reactors. With the advancement of science and technology, demand for nano-dysprosium oxide with large surface areas is increasing. As particle size decreases to nanometers, the increased specific surface area produces surface effects, coupled with quantum size effects and macroscopic quantum tunneling effects, making it a foundation for the development of special functional materials. For example, in ceramic capacitors, nano-dysprosium oxide particles can significantly improve product performance.

[0003] The Chinese invention patent with publication number CN111017977A discloses a method for preparing nano-dysprosium oxide for dielectric ceramic capacitors. The patent prepares nano-dysprosium oxide by coprecipitation. Although it solves the problem of large particle size and poor dispersion performance of existing rare earth oxides, the particle size distribution of the prepared nano-dysprosium oxide is uneven and the specific surface area is small. When D50 = 0.2μm, its specific surface area is only 14.2m 2 / g. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing nano-dysprosium oxide particles.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for preparing nano-dysprosium oxide particles comprises the following steps:

[0007] (1) Adding dysprosium oxide to a nitric acid solution to prepare a dysprosium nitrate solution;

[0008] (2) Add deionized water to the reactor, heat it to 50-70°C, add surfactant, and stir until dissolved;

[0009] (3) slowly adding dysprosium nitrate solution to the reactor, the addition time is controlled within 2-3 hours, the temperature is controlled at 50-70°C during the addition process, and the pH of the system is controlled at 5.5-7.5 by adding ammonium carbonate solution during the addition process. After the addition is completed, the mixture is stirred for 1-2 hours to obtain a white precipitate, which is then filtered and washed to obtain a wet product;

[0010] (4) calcining the wet product at 600-900°C for 2-5h, crushing and sieving to obtain nano-dysprosium oxide;

[0011] The surfactant has a structural formula as shown in formula (I):

[0012] (I).

[0013] The number average molecular weight of the surfactant is 3000-3500.

[0014] The concentration of the dysprosium nitrate solution in step (1) is 0.5-1 mol / L.

[0015] The concentration of the ammonium carbonate solution in step (3) is 0.5-1 mol / L.

[0016] The mass of the surfactant added in step (2) is 0.1-0.2 times the mass of the dysprosium nitrate solution added in step (3).

[0017] The surfactant is prepared by the following method:

[0018] S1: Add 100 parts by weight of deionized water, 25 parts by weight of maleic anhydride, 15-20 parts by weight of itaconic acid, and 5 parts by weight of sulfuric acid to a reactor in sequence, raise the temperature to 65-70°C, and stir until dissolved;

[0019] S2: Slowly add 5-8 parts by weight of a 20 wt% benzene solution of dibenzoyl peroxide and 30-40 parts by weight of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate to the reactor at the same time, control the addition temperature at 65-70°C, and slowly add for 3-4 hours. After the addition is complete, continue to keep warm for 1-2 hours;

[0020] S3: Cooling to room temperature, filtering, and washing to obtain a polymer surfactant with a solid content of 45-50 wt%.

[0021] The reaction equation for the preparation of the surfactant is as follows:

[0022]

[0023] Furthermore, dysprosium oxide prepared using the method for preparing nano-dysprosium oxide particles is used in the field of ceramic capacitors.

[0024] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0025] (1) The present invention prepares a novel surfactant for preparing nano-dysprosium oxide particles by free radical polymerization of maleic anhydride, itaconic acid and sodium 2-acryloyl-2-methylpropanesulfonate under the initiation of an initiator.

[0026] (2) The present invention avoids the agglomeration of dysprosium oxide particles during the coprecipitation process by using the prepared polymer surfactant. The prepared nano-dysprosium oxide particles are uniform in size, have a high specific surface area and long-term storage stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a transmission electron microscope image of dysprosium oxide prepared in Example 4.

[0028] Figure 2 This is a transmission electron microscope image of dysprosium oxide prepared in Example 5.

[0029] Figure 3 This is a transmission electron microscope image of dysprosium oxide prepared in Example 6.

[0030] Figure 4 This is a transmission electron microscope image of dysprosium oxide prepared in Comparative Example 1.

[0031] Figure 5 This is a transmission electron microscope image of dysprosium oxide prepared in Comparative Example 2.

[0032] Figure 6 This is a transmission electron microscope image of dysprosium oxide prepared in Comparative Example 3.

[0033] Figure 7 This is a transmission electron microscope image of dysprosium oxide prepared in Comparative Example 6. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0035] Example 1, preparation of surfactant:

[0036] S1: Add 1000g deionized water, 250g maleic anhydride, 150g itaconic acid, and 50g 73.5wt% sulfuric acid to a reactor in sequence, heat to 65°C, and stir until dissolved;

[0037] S2: 80 g of a 20 wt% benzene solution of dibenzoyl peroxide and 300 g of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate were slowly added dropwise to the reactor at the same time. The addition temperature was controlled at 65° C. and the addition was slowly continued for 3 h. After the addition was completed, the mixture was kept warm for 1 h.

[0038] S3: Cooling to room temperature, filtering, and washing with 200 g of deionized water to obtain a polymer surfactant with a solid content of 45.2 wt % and a number average molecular weight of 3019.

[0039] Example 2, preparation of surfactant:

[0040] S1: Add 1000g deionized water, 250g maleic anhydride, 180g itaconic acid, and 50g 73.5wt% sulfuric acid to a reactor in sequence, heat to 65°C, and stir until dissolved;

[0041] S2: 60 g of a 20 wt% benzene solution of dibenzoyl peroxide and 350 g of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate were slowly added dropwise to the reactor at the same time. The addition temperature was controlled at 65°C and the addition was slowly continued for 3.5 h. After the addition was completed, the mixture was kept warm for 1.5 h.

[0042] S3: Cool to room temperature, filter, and wash with 200 g of deionized water to obtain a polymer surfactant solution with a solid content of 47.4 wt % and a number average molecular weight of 3316.

[0043] Example 3, preparation of surfactant:

[0044] S1: Add 1000g deionized water, 250g maleic anhydride, 200g itaconic acid, and 50g 73.5wt% sulfuric acid to a reactor in sequence, raise the temperature to 70°C, and stir until dissolved;

[0045] S2: 50 g of a 20 wt% benzene solution of dibenzoyl peroxide and 400 g of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate were slowly added dropwise to the reactor at the same time. The addition temperature was controlled at 70° C. and the addition was slowly continued for 4 h. After the addition was completed, the mixture was kept warm for 2 h.

[0046] S3: Cooling to room temperature, filtering, and washing with 200 g of deionized water to obtain a polymer surfactant with a solid content of 49.6 wt % and a number average molecular weight of 3486.

[0047] Example 4, Preparation of Nano-Dysprosium Oxide Particles:

[0048] (1) Add dysprosium oxide to 3 mol / L nitric acid solution to prepare 0.5 mol / L dysprosium nitrate solution;

[0049] (2) Add 15 kg of deionized water to the reactor, heat it to 50°C, add 0.8 kg of the surfactant represented by formula (I) (prepared in Example 1), and stir until dissolved;

[0050] (3) Slowly add 8 kg of dysprosium nitrate solution to the reactor, the addition time is controlled within 2 hours, and the temperature is controlled at 50°C during the addition. During the addition of dysprosium nitrate solution, the pH of the system is controlled to 5.5-6.5 by adding 0.5 mol / L ammonium carbonate solution. After the addition is completed, stirring is continued for 1 hour to obtain a white precipitate, which is filtered and washed with 1 kg of deionized water to obtain a wet product;

[0051] (4) The wet product was calcined at 600°C for 5 h, crushed and sieved using a pulverizer to obtain nano-dysprosium oxide.

[0052] Example 5, Preparation of Nano-Dysprosium Oxide Particles:

[0053] (1) Add dysprosium oxide to 3 mol / L nitric acid solution to prepare 0.75 mol / L dysprosium nitrate solution;

[0054] (2) Add 15 kg of deionized water to the reactor, heat it to 60°C, add 1.2 kg of the surfactant represented by formula (I) (prepared in Example 2), and stir until dissolved;

[0055] (3) Slowly add 8 kg of dysprosium nitrate solution to the reactor, the addition time is controlled within 2.5 hours, and the temperature is controlled at 60°C during the addition. During the addition of dysprosium nitrate solution, the pH of the system is controlled to 6-7 by adding 0.75 mol / L ammonium carbonate solution. After the addition is completed, stirring is continued for 1.5 hours to obtain a white precipitate, which is filtered and washed with 1 kg of deionized water to obtain a wet product;

[0056] (4) The wet product was calcined at 800°C for 3.5 hours, crushed and sieved using a crusher to obtain nano-dysprosium oxide.

[0057] Example 6, Preparation of Nano-Dysprosium Oxide Particles:

[0058] (1) Add dysprosium oxide to 3 mol / L nitric acid solution to prepare 1 mol / L dysprosium nitrate solution;

[0059] (2) Add 15 kg of deionized water to the reactor, heat it to 70°C, add 1.6 kg of the surfactant represented by formula (I) (prepared in Example 3), and stir until dissolved;

[0060] (3) Slowly add 8 kg of dysprosium nitrate solution to the reactor, the addition time is controlled within 3 hours, and the temperature is controlled at 70°C during the addition process. During the addition of dysprosium nitrate solution, the pH of the system is controlled to 6.5-7.5 by adding 1 mol / L ammonium carbonate solution. After the addition is completed, stirring is continued for 2 hours to obtain a white precipitate, which is filtered and washed with 1 kg of deionized water to obtain a wet product;

[0061] (4) The wet product was calcined at 900°C for 2 h, crushed and sieved using a crusher to obtain nano-dysprosium oxide.

[0062] In Comparative Example 1, the preparation method of dysprosium oxide is substantially the same as that in Example 5, except that the number average molecular weight of the surfactant represented by formula (I) added in step (2) is 2738.

[0063] A surfactant with a number average molecular weight of 2738 was prepared by the following method:

[0064] S1: Add 1000g deionized water, 250g maleic anhydride, 160g itaconic acid, and 50g 73.5wt% sulfuric acid to a reactor in sequence, heat to 65°C, and stir until dissolved;

[0065] S2: 100 g of a 20 wt% benzene solution of dibenzoyl peroxide and 250 g of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate were slowly added dropwise to the reactor at the same time. The addition temperature was controlled at 65° C. and the addition was slowly continued for 3 h. After the addition was completed, the mixture was kept warm for 1 h.

[0066] S3: Cooling to room temperature, filtering, and washing with 200 g of deionized water to obtain a polymer surfactant with a solid content of 45.2 wt % and a number average molecular weight of 2738.

[0067] In Comparative Example 2, the preparation method of dysprosium oxide is substantially the same as that in Example 5, except that the number average molecular weight of the surfactant represented by formula (I) added in step (2) is 3864.

[0068] A surfactant with a number average molecular weight of 3864 was prepared by the following method:

[0069] S1: Add 1000g deionized water, 250g maleic anhydride, 300g itaconic acid, and 50g 73.5wt% sulfuric acid to a reactor in sequence, heat to 70°C, and stir until dissolved;

[0070] S2: 4.50 g of a 20 wt% benzene solution of dibenzoyl peroxide and 420 g of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate were slowly added dropwise to the reactor at the same time. The addition temperature was controlled at 70°C for 5 h. After the addition was completed, the mixture was kept warm for 2 h.

[0071] S3: Cooling to room temperature, filtering, and washing with 200 g of deionized water to obtain a polymer surfactant with a solid content of 49.6 wt % and a number average molecular weight of 3864.

[0072] Comparative Example 3: The preparation method of dysprosium oxide is basically the same as that of Example 5, except that the surfactant in step (2) is replaced by an equal weight of polydiallyldimethylammonium chloride aqueous solution (PDDA, Mw=150000, 30wt%).

[0073] Comparative Example 4: The preparation method of dysprosium oxide is basically the same as that of Example 5, except that the surfactant in step (2) is replaced by an equal weight of polyvinyl pyrrolidone (Mw=130,000).

[0074] Comparative Example 5. The preparation method of dysprosium oxide is basically the same as that of Example 5, except that the surfactant in step (2) is replaced by an equal weight of polyvinyl pyrrolidone (Mw=58,000).

[0075] Comparative Example 6: The preparation method of dysprosium oxide is basically the same as that of Example 5, except that the surfactant in step (2) is replaced by an equal weight of 38 wt% CTAB aqueous solution.

[0076] Comparative Example 7: The preparation method of dysprosium oxide is basically the same as that of Example 5, except that the surfactant in step (2) is replaced by an equal weight of 38 wt% CTAC aqueous solution.

[0077] In Comparative Example 8, the preparation method of dysprosium oxide is basically the same as that in Example 5, except that the surfactant in step (2) is replaced by 0.4 kg of maleic anhydride, 0.28 kg of itaconic acid, and 0.54 kg of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate.

[0078] The particle size and specific surface area of ​​the dysprosium oxide prepared in Examples 4-6 and the comparative example were tested. The specific surface area of ​​the dysprosium oxide prepared in Examples 4-6 and the comparative example was also tested after calcination at 800°C for 12 hours (calcination heating rate of 5°C / min) and aging. The test results are shown in Table 1.

[0079] Specific surface area test method: Monosorb specific surface area tester was used to perform the test using the BET single-point method.

[0080] Particle size test method: ethanol was used as the dispersing solvent of the sample, ultrasonic dispersion was performed using an ultrasonic homogenizer for 3 minutes, and the particle size distribution D50 and D98 of the dispersed sample were tested using an LS 13 320 XR laser diffraction particle size analyzer.

[0081] The morphology of the dysprosium oxide prepared in Examples 4-6 and Comparative Examples 1, 2, 3, and 6 was characterized using a JEM-1400 transmission electron microscope.

[0082] Table 1

[0083]

[0084] As can be seen from Examples 4-6 in Table 1, the particle size difference between D50 and D98 prepared by the present invention is relatively small, with the largest particle size difference being only 0.04 μm, indicating that the particle size distribution is relatively uniform, and the specific surface area is within 31 m 2 / g or more, and the specific surface area after aging is also 28m 2 / g or more, indicating that the dysprosium oxide prepared by the method of the present invention has excellent long-term storage stability.

[0085] Comparative Examples 1 and 2 are dysprosium oxide particles prepared using surfactants represented by formula (I) with number average molecular weights of 2738 and 3864, respectively. It can be seen from the D50 and D98 particle size data that the particle sizes of the dysprosium oxide particles prepared in the comparative examples are quite different, and the specific surface area of ​​the dysprosium oxide prepared in the comparative examples is less than 22 m 2 / g.

[0086] Comparative Examples 3-7 are dysprosium oxide particles prepared using other surfactants. It can be seen from the data in Table 1 that the D50 and D98 particle sizes of dysprosium oxide prepared using PDDA, PVP, CTAB, and CTAC as surfactants are quite different. The specific surface area of ​​the newly prepared particles is much smaller than that of Examples 4-6, and the specific surface area decreases more seriously after aging.

[0087] Comparative Example 8 is a dysprosium oxide prepared using maleic anhydride, itaconic acid, and sodium 2-acryloyl-2-methylpropanesulfonate as surfactants. Its D50 is greater than 1 μm, and the specific surface area of ​​the new product is only 7.03 m 2 / g.

[0088] pass Figure 1-7 It can be seen that the particle sizes of the dysprosium oxide particles prepared in Examples 4-6 are relatively uniform, while the particle sizes of the dysprosium oxide particles prepared in Comparative Examples 1, 2, 3, and 6 are relatively poorly uniform.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in this field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing nano-dysprosium oxide particles, characterized in that: The following steps are involved: (1) Adding dysprosium oxide to a nitric acid solution to prepare a dysprosium nitrate solution; (2) Add deionized water to the reactor, heat it to 50-70°C, add surfactant, and stir until dissolved; (3) slowly adding dysprosium nitrate solution to the reactor, the addition time is controlled within 2-3 hours, the temperature is controlled at 50-70°C during the addition process, and the pH of the system is controlled at 5.5-7.5 by adding ammonium carbonate solution during the addition process. After the addition is completed, stirring is continued for 1-2 hours to obtain a white precipitate, which is then filtered and washed to obtain a wet product; (4) calcining the wet product at 600-900°C for 2-5h, crushing and sieving to obtain nano-dysprosium oxide; The surfactant has a structural formula as shown in formula (I): （I）； The number average molecular weight of the surfactant is 3000-3500; The surfactant is prepared by the following method: S1: Add 100 parts by weight of deionized water, 25 parts by weight of maleic anhydride, 15-20 parts by weight of itaconic acid, and 5 parts by weight of sulfuric acid to a reactor in sequence, raise the temperature to 65-70°C, and stir until dissolved; S2: Slowly add 5-8 parts by weight of a 20 wt% benzene solution of dibenzoyl peroxide and 30-40 parts by weight of a 50 wt% aqueous solution of sodium 2-acryloyl-2-methylpropanesulfonate to the reactor at the same time, control the addition temperature at 65-70°C, and slowly add for 3-4 hours. After the addition is complete, continue to keep warm for 1-2 hours; S3: Cooling to room temperature, filtering, and washing to obtain a polymer surfactant with a solid content of 45-50 wt%.

2. The method for preparing nano-dysprosium oxide particles according to claim 1, wherein: The concentration of the dysprosium nitrate solution in step (1) is 0.5-1 mol / L.

3. The method for preparing nano-dysprosium oxide particles according to claim 1, wherein: The concentration of the ammonium carbonate solution added dropwise in step (3) is 0.5-1 mol / L.

4. The method for preparing nano-dysprosium oxide particles according to claim 1, wherein: The mass of the surfactant added in step (2) is 0.1-0.2 times the mass of the dysprosium nitrate solution added in step (3).

5. Application of dysprosium oxide prepared by the method for preparing nano-dysprosium oxide particles according to any one of claims 1 to 4 in the field of ceramic capacitors.

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