Praseodymium-neodymium oxide and method for producing the same

Abstract

The application discloses praseodymium-neodymium oxide and a preparation method thereof. The preparation method comprises the following steps: 1) adding a praseodymium-neodymium chloride solution and ammonia water into an ammonium acetate solution in a parallel flow mode, performing solid-liquid separation after the reaction is completed, and obtaining a praseodymium-neodymium oxide precursor; 2) performing calcination on the praseodymium-neodymium oxide precursor, and obtaining praseodymium-neodymium oxide. The praseodymium-neodymium oxide has a porous sheet structure. The praseodymium-neodymium oxide with the porous sheet structure can be obtained by using the preparation method.

Description

Technical Field

[0001] This invention relates to a praseodymium-neodymium oxide and its preparation method, and more particularly to a porous, sheet-like praseodymium-neodymium oxide and its preparation method. Background Technology

[0002] In recent years, the increasingly refined technology for preparing rare earth compounds has led to advancements in the preparation of rare earth compounds with unique properties. Praseodymium-neodymium oxides are important light rare earth oxide products. Since the 1970s, market demand for praseodymium-neodymium oxides has increased rapidly, especially for those with unique morphologies, which have wide applications in glass, ceramics, catalysis, and magnetic materials. Researchers have studied and prepared praseodymium-neodymium oxides with specific morphologies.

[0003] For example, CN102531024A discloses a method for preparing large-particle, spherical praseodymium-neodymium oxide. The method involves heating a praseodymium-neodymium chloride solution to 85-95°C, adding a certain concentration of ammonium bicarbonate solution to precipitate the precipitate, maintaining the temperature for aging, washing, and filtering to obtain basic praseodymium-neodymium carbonate precipitate, centrifuging the basic praseodymium-neodymium carbonate precipitate to dry it, and then igniting it to obtain spherical praseodymium-neodymium oxide product.

[0004] CN102532760A discloses a method for preparing large-particle, flake-shaped praseodymium-neodymium oxide. The method involves heating a praseodymium-neodymium chloride solution to 60°C, adding a certain concentration of ammonium bicarbonate solution to precipitate the precipitate, maintaining the temperature for aging, washing, and filtering to obtain praseodymium-neodymium carbonate precipitate, centrifuging the praseodymium-neodymium carbonate precipitate to dry it, and then calcining it to obtain flake-shaped praseodymium-neodymium oxide.

[0005] CN114956149A discloses a method for preparing spherical praseodymium-neodymium oxide. The method involves mixing praseodymium-neodymium oxide with an inorganic acid solution, adjusting the pH to 2-4 to obtain a first mixture; adding urea to the first mixture at 40-60°C to obtain a second mixture; reacting the second mixture at 125-155°C for 1-5 hours, followed by washing, drying, and calcination to obtain spherical praseodymium-neodymium oxide particles.

[0006] CN116903022A discloses a rare earth oxide particle and its preparation method. Specifically, this patent document discloses mixing an aqueous solution of ammonium bicarbonate and an aqueous solution of sodium citrate to obtain an adjusting solution with a pH of 7.5. At 20°C, the adjusting solution and an aqueous solution of praseodymium-neodymium sulfate are added dropwise in parallel to a reaction vessel containing 50 mL of deionized water. After the addition is complete, the reaction is stirred for another 50 min to obtain a solid-liquid mixture containing a precursor precipitate. The solid-liquid mixture containing the precursor precipitate is aged, filtered, washed, and dried, and then calcined to obtain praseodymium-neodymium oxide particles. The surface morphology of the obtained praseodymium-neodymium oxide particles under a scanning electron microscope shows spherical aggregates formed by plate-like crystals. Summary of the Invention

[0007] One object of the present invention is to provide a method for preparing praseodymium-neodymium oxide, wherein the praseodymium-neodymium oxide obtained by the method has a substantially porous lamellar structure. Another object of the present invention is to provide the praseodymium-neodymium oxide obtained by the above method. The present invention achieves the above objects using the following technical solutions.

[0008] On one hand, the present invention provides a method for preparing praseodymium-neodymium oxide, comprising the following steps:

[0009] 1) Praseodymium chloride solution and ammonia water were added dropwise to ammonium acetate solution in a co-current manner. After the reaction was completed, solid-liquid separation was performed to obtain praseodymium oxide precursor.

[0010] 2) The praseodymium-neodymium oxide precursor was calcined to obtain praseodymium-neodymium oxide;

[0011] The praseodymium-neodymium oxide has a porous, plate-like structure.

[0012] According to the preparation method of the present invention, preferably, during the parallel-flow dropwise addition, the molar ratio of rare earth ions in the praseodymium chloride solution to the solute in the ammonia water is controlled to be 1:2.8 to 3.4.

[0013] According to the preparation method of the present invention, preferably, the concentration of rare earth ions in the praseodymium chloride neodymium solution is 80-120 g / L.

[0014] According to the preparation method of the present invention, preferably, the concentration of ammonia water is 4-5 mol / L.

[0015] According to the preparation method of the present invention, preferably, the concentration of the ammonium acetate solution is 0.5 to 2.2 mol / L.

[0016] According to the preparation method of the present invention, preferably, when the reaction is added dropwise in parallel flow, the temperature of the reaction system is 40–80°C.

[0017] According to the preparation method of the present invention, preferably, the reaction system is stirred during the co-current dropwise addition; wherein the stirring speed is 150-300 rpm.

[0018] According to the preparation method of the present invention, preferably, in step 1), after the parallel droplet addition is completed, the pH value of the reaction system is adjusted to 8.5-11.

[0019] According to the preparation method of the present invention, preferably, in step 2), the calcination temperature is 800-1100℃ and the calcination time is 1-6h.

[0020] On the other hand, the present invention also provides a praseodymium-neodymium oxide obtained according to the preparation method described above, which has a porous plate-like structure.

[0021] The praseodymium-neodymium oxide obtained by the preparation method of the present invention has a porous plate-like structure, good crystallinity, good dispersibility, and is basically free from adhesion and agglomeration. According to a preferred embodiment of the present invention, using an ammonium acetate solution of a certain concentration as the base liquid and controlling the dropping rate of the praseodymium chloride solution and ammonia water during co-current dropping is beneficial to obtaining praseodymium-neodymium oxide particles with a porous plate-like morphology. Attached Figure Description

[0022] Figure 1 The image shows the XRD pattern of the praseodymium-neodymium oxide obtained in Example 1 of this invention.

[0023] Figure 2 This is a SEM image of the praseodymium-neodymium oxide obtained in Example 1 of the present invention.

[0024] Figure 3 This is a TEM image of the praseodymium-neodymium oxide obtained in Example 1 of the present invention.

[0025] Figure 4 This is an HDTEM image of the praseodymium-neodymium oxide obtained in Example 1 of the present invention.

[0026] Figure 5 SEM image of the praseodymium-neodymium oxide obtained in Comparative Example 1.

[0027] Figure 6 SEM image of the praseodymium-neodymium oxide obtained in Comparative Example 2. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0029] The method for preparing praseodymium-neodymium oxide of the present invention includes the following steps: (1) a parallel-flow dropwise addition and post-treatment step; and (2) a calcination step. In addition, it also includes a step for preparing an ammonium acetate solution. A detailed description follows.

[0030] <Post-treatment steps for parallel-flow drip addition>

[0031] Praseodymium-neodymium chloride solution and ammonia water were added dropwise to ammonium acetate solution in a co-current flow. After the reaction was complete, solid-liquid separation was performed to obtain the praseodymium-neodymium oxide precursor. Surprisingly, this invention reveals that porous, plate-like praseodymium-neodymium oxide particles can be obtained in this manner.

[0032] In this invention, the concentration of rare earth ions in the praseodymium-neodymium chloride solution can be 80–120 g / L, preferably 90–110 g / L. For example, it can be 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, or 120 g / L.

[0033] The concentration of ammonia water can be 3.5–5 mol / L, preferably 4–5 mol / L, and more preferably 4–4.5 mol / L.

[0034] During parallel-flow addition, the molar ratio of rare earth ions in the praseodymium chloride solution to the solute in the ammonia solution is controlled to be 1:2.8–3.4, preferably 1:3.0–3.3, and more preferably 1:3.0–3.2. The solute in the ammonia solution refers to NH3 in the ammonia solution.

[0035] Ammonium acetate solution is used as the base solution. This invention has found that using ammonium acetate solution as the base solution can help obtain praseodymium-neodymium oxide particles with specific morphologies. The volume of the base solution can be 5% to 25% of the reaction vessel volume, for example, 5%, 10%, 15%, 20%, or 25%.

[0036] Ammonium acetate solution can be prepared by dissolving solid ammonium acetate in deionized water. The ammonium acetate solution contains no crystals and is a complete solution. The concentration of the ammonium acetate solution can be 0.5–2.2 mol / L, preferably 1.0–2.0 mol / L, and more preferably 1.2–1.8 mol / L. For example, it can be 0.8 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.5 mol / L, 1.7 mol / L, 1.8 mol / L, or 2.0 mol / L.

[0037] When adding the reaction mixture dropwise in parallel, the temperature of the reaction system can be 40–80°C, preferably 50–80°C, and more preferably 65–80°C.

[0038] When adding the reaction mixture dropwise, the reaction system needs to be stirred. The stirring speed can be 150–300 rpm, preferably 200–300 rpm, and more preferably 230–250 rpm. This is beneficial for obtaining praseodymium-neodymium oxide with good crystallinity and porous, plate-like structure.

[0039] After the parallel dropwise addition is complete, adjust the pH of the reaction system to 8.5–11, preferably 9.0–10.5, and more preferably 9.0–10.0. This is beneficial for the complete precipitation of rare earth ions and improves the yield.

[0040] After adjusting the pH value of the reaction system, continue stirring the reaction for 20–50 min, preferably 25–45 min, and more preferably 30–40 min.

[0041] After the reaction is complete, the reaction system can be cooled to room temperature, followed by solid-liquid separation. Solid-liquid separation can be performed by filtration or centrifugation, with filtration being preferred. During filtration, the filter cake can be washed multiple times with deionized water, for example, 2 to 5 times, preferably 3 to 4 times. After washing with deionized water, it is then washed 1 to 2 times with alcohol. The alcohol used can be selected from methanol, ethanol, and isopropanol, with ethanol being preferred. This yields a praseodymium-neodymium oxide precursor.

[0042] In some embodiments, at 40–80°C, praseodymium chloride solution and ammonia water are added dropwise in parallel to ammonium acetate solution as the base solution. After the addition is complete, the pH of the reaction system is adjusted to 9.0–10.5, and the reaction is continued to be stirred for 25–45 min. After the reaction is complete, the mixture is filtered, and the filter cake is washed with deionized water 3–4 times, and then washed with ethanol 1–2 times to obtain the praseodymium-neodymium oxide precursor.

[0043] <Roasting Steps>

[0044] Praseodymium-neodymium oxide precursors are calcined to obtain praseodymium-neodymium oxide.

[0045] The calcination temperature can be 800–1100℃, preferably 850–1000℃, and more preferably 900–950℃. The calcination time can be 1–6 hours, preferably 2–5 hours, and more preferably 3–4 hours. This is beneficial for obtaining praseodymium-neodymium oxide particles with good dispersibility.

[0046] According to one embodiment of the present invention, the preparation method of praseodymium-neodymium oxide includes the following specific steps:

[0047] 1) At 40–80°C, praseodymium chloride solution and ammonia water were added dropwise in parallel to ammonium acetate solution as the base solution. After the addition was complete, the pH of the reaction system was adjusted to 9.0–10.5, and the reaction was stirred for 25–45 min. After the reaction was complete, the mixture was filtered, and the filter cake was rinsed with deionized water 3–4 times and with ethanol 1–2 times to obtain praseodymium-neodymium oxide precursor.

[0048] 2) The praseodymium-neodymium oxide precursor was calcined at 850–1000 °C for 2–5 h to obtain praseodymium-neodymium oxide. The obtained praseodymium-neodymium oxide has a porous lamellar structure.

[0049] This invention controls the morphology of praseodymium-neodymium oxide by controlling the molar ratio of alkaline substances in ammonia water and rare earth ions in rare earth chloride solution added per unit time during the precursor preparation reaction, as well as the concentration of ammonium acetate in the base solution. This method is simple to operate, requires no dispersant, and has the potential advantage of large-scale production. The praseodymium-neodymium oxide particles prepared using this method have a porous, plate-like structure, good dispersibility, and are essentially free from adhesion and agglomeration.

[0050] The test methods for the following embodiments and comparative examples are described below:

[0051] XRD: Tests were performed using an X'Pert Pro X-ray diffractometer from Malvern Panaco.

[0052] SEM: The tests were performed using a Zeiss Sigma 500 field emission scanning electron microscope.

[0053] TEM and HDTEM: Both were tested using a Thermo Fisher Scientific Talos F200i transmission electron microscope.

[0054] Example 1

[0055] Dissolve 46.2g of ammonium acetate solid in 400mL of deionized water to prepare a 1.5mol / L ammonium acetate solution for later use.

[0056] At 80℃ and 250 rpm, 200 mL of a 150 g / L praseodymium chloride solution and 150 mL of 4 mol / L ammonia solution were added dropwise in parallel to a reaction vessel containing the aforementioned ammonium acetate solution. After the addition was complete, the pH of the reaction system was adjusted to 9.0, and stirring was continued for 30 min. After the reaction was complete, the mixture was filtered, and the filter cake was washed three times with deionized water and once with ethanol to obtain the praseodymium-neodymium oxide precursor. During the parallel-flow addition, the molar ratio of rare earth ions in the praseodymium chloride solution to the solute in the ammonia solution was controlled at 1:3.0.

[0057] The praseodymium-neodymium oxide precursor obtained above was calcined at 900°C for 3 hours to obtain praseodymium-neodymium oxide.

[0058] The XRD results of the obtained praseodymium-neodymium oxide are shown in the figure. Figure 1 Because the XRD peaks of praseodymium oxide and neodymium oxide are too close together, the standard chromatogram for praseodymium oxide was not plotted. SEM results are shown below. Figure 2 TEM results are shown below. Figure 3 HDTEM results are shown in Figure 4 The test results show that the praseodymium-neodymium oxide obtained by the preparation method of the present invention is a porous, plate-like praseodymium-neodymium oxide particle with good crystallinity, good dispersibility, and basically no adhesion or agglomeration.

[0059] Example 2

[0060] Dissolve 46.2g of ammonium acetate solid in 400mL of deionized water to prepare a 1.5mol / L ammonium acetate solution for later use.

[0061] At 70℃ and 200 rpm, 200 mL of a 150 g / L praseodymium chloride solution and 150 mL of ammonia solution (4 mol / L) were added dropwise in parallel to a reaction vessel containing the aforementioned ammonium acetate solution. After the addition was complete, the pH of the reaction system was adjusted to 10.0, and stirring was continued for 30 min. After the reaction was complete, the mixture was filtered, and the filter cake was washed three times with deionized water and once with ethanol to obtain the praseodymium-neodymium oxide precursor. During the parallel-flow addition, the molar ratio of rare earth ions in the praseodymium chloride solution to the solute in the ammonia solution was controlled at 1:3.1.

[0062] The praseodymium-neodymium oxide precursor obtained above was calcined at 900°C for 3 hours to obtain praseodymium-neodymium oxide.

[0063] The obtained praseodymium-neodymium oxide is a porous, plate-like praseodymium-neodymium oxide particle with good crystallinity, good dispersibility, and basically no adhesion or agglomeration.

[0064] Comparative Example 1

[0065] The only difference from Example 1 is that the ammonium acetate solution was replaced with water. The SEM results of the resulting praseodymium-neodymium oxide are shown in [Figure 1]. Figure 5 .

[0066] Comparative Example 2

[0067] The only difference from Example 1 is that ammonia was replaced with ammonium bicarbonate solution. The SEM results of the obtained praseodymium-neodymium oxide are shown below. Figure 6 .

[0068] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for preparing praseodymium-neodymium oxide, characterized in that, Includes the following steps: 1) Praseodymium chloride solution and ammonia water were added dropwise to ammonium acetate solution in a co-current flow. After the reaction was complete, solid-liquid separation was performed to obtain the praseodymium oxide precursor. During the co-current dropwise addition, the molar ratio of rare earth ions in the praseodymium chloride solution to the solute in the ammonia water was controlled at 1:2.8–3.4; the concentration of the ammonium acetate solution was 0.5–2.2 mol / L. 2) The praseodymium-neodymium oxide precursor was calcined to obtain praseodymium-neodymium oxide; The praseodymium-neodymium oxide has a porous, plate-like structure.

2. The preparation method according to claim 1, characterized in that, The concentration of rare earth ions in praseodymium chloride neodymium solution is 80–120 g / L.

3. The preparation method according to claim 1, characterized in that, The concentration of ammonia water is 4–5 mol / L.

4. The preparation method according to claim 1, characterized in that, When added dropwise in parallel flow, the temperature of the reaction system is 40–80 °C.

5. The preparation method according to claim 1, characterized in that, When adding the mixture dropwise, the reaction system is stirred; the stirring speed is 150–300 rpm.

6. The preparation method according to claim 1, characterized in that, In step 1), after the parallel droplet addition is complete, adjust the pH of the reaction system to 8.5–11.

7. The preparation method according to claim 1, characterized in that, In step 2), the roasting temperature is 800–1100℃ and the roasting time is 1–6 h.

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