A preparation method of flower ball-shaped cerium oxide

Abstract

The present invention relates to the technical field of cerium oxide preparation, and in particular to a method for preparing flower-ball-shaped cerium oxide. The preparation method provided by the present invention comprises: mixing a soluble cerium salt solution and hydrogen peroxide, performing an oxidation precipitation reaction, and obtaining a solid product by solid-liquid separation; washing the solid product and drying it to obtain the flower-ball-shaped cerium oxide; the pH value of the soluble cerium salt solution is 2-4, the temperature of the oxidation precipitation reaction is 30-90°C, and the drying temperature is 30-90°C. The preparation method is simple to operate, the process flow is short, and the calcination process with large energy consumption in the traditional preparation process of cerium oxide powder is omitted, which is green and energy-saving and conducive to industrial production; the cerium oxide powder prepared by the preparation method of the present invention has a special microscopic morphology, which is a flower-ball-shaped particle with a loose and porous surface; the preparation method of the present invention provides a new idea for preparing cerium oxide powder with a special microscopic morphology.

Description

Technical Field

[0001] The invention relates to the technical field of cerium oxide preparation, in particular to a method for preparing flower-spherical cerium oxide. Background Art

[0002] Cerium oxide is a cheap and widely used light rare earth oxide, which has been used in luminescent materials, polishing agents, ultraviolet absorbers, automobile exhaust purification catalysts, chemical decolorizers for glass, radiation-resistant glass and electronic ceramics, etc. The microscopic morphology of cerium oxide determines its physical and chemical properties, which directly affects its use. For example, the addition of ultrafine cerium oxide can not only reduce the sintering temperature of ceramics but also increase the density of ceramics. Ultrafine cerium oxide with a large specific surface area can be used as a catalyst, and ultrafine spherical cerium oxide polishing powder can be used for high-speed polishing of ultra-precision optical and electronic components.

[0003] With the development of science and technology, the market demand for high-purity ultrafine yttrium oxide powder is also increasing rapidly, and the special requirements for its morphology are also changing. However, spherical cerium oxide is still the most popular in the market. At present, the preparation methods of ultrafine spherical cerium oxide powder are mainly homogeneous precipitation method, sol-gel method, high-temperature hydrolysis method and microemulsion method. These methods require the addition of more reaction aids, such as dispersants or surfactants, resulting in high costs, and the precursor post-processing process is long, which is difficult to use for large-scale economical and efficient production in industry. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for preparing flower-spherical cerium oxide, which is simple to operate, low in cost, and conducive to industrial production.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing flower-spherical cerium oxide, comprising the following steps:

[0007] Mixing a soluble cerium salt solution and hydrogen peroxide, performing an oxidation precipitation reaction, and performing solid-liquid separation to obtain a solid product;

[0008] The solid product is washed and dried to obtain the flower ball-shaped cerium oxide;

[0009] The pH value of the soluble cerium salt solution is 2-4, the temperature of the oxidation precipitation reaction is 30-90°C, and the drying temperature is 30-90°C.

[0010] Preferably, the pH value of the soluble cerium salt solution is 2.5-3.5.

[0011] Preferably, the soluble cerium salt in the soluble cerium salt solution includes cerium chloride and / or cerium nitrate.

[0012] Preferably, the concentration of the soluble cerium salt in the soluble cerium salt solution is 0.5-2.5 mol / L.

[0013] Preferably, the mass concentration of the hydrogen peroxide is 10-50%.

[0014] Preferably, the molar ratio of the soluble cerium salt to the hydrogen peroxide in the soluble cerium salt solution is 1:(2-5).

[0015] Preferably, the oxidation precipitation reaction is carried out under stirring;

[0016] The stirring speed is 50-300 rpm.

[0017] Preferably, the oxidation precipitation reaction time is 0.5~3h.

[0018] Preferably, the drying time is 2 to 6 hours.

[0019] Preferably, the flower-spherical cerium oxide is a flower-spherical structure formed by agglomeration of layered cerium oxide.

[0020] The invention provides a method for preparing flower-ball-shaped cerium oxide, comprising the following steps: mixing a soluble cerium salt solution and hydrogen peroxide, performing an oxidation precipitation reaction, and performing solid-liquid separation to obtain a solid product; washing the solid product and drying it to obtain the flower-ball-shaped cerium oxide; the pH value of the soluble cerium salt solution is 2-4, the temperature of the oxidation precipitation reaction is 30-90°C, and the drying temperature is 30-90°C. The preparation method of the invention can oxidize trivalent cerium into tetravalent cerium by hydrogen peroxide, and tetravalent cerium is precipitated as a precipitate under acidic conditions (when the pH is about 2), and cerium hydroxide is unstable and easily decomposed into cerium dioxide and water. Cerium is most stable when hydrogen peroxide has a pH of 2.5-4.5, and decomposes violently when the temperature is greater than 90°C, and the decomposition rate can reach more than 90%. Control the amount ratio of the substance, temperature, and pH, so that the cerium is slowly precipitated, slowly stirred to form a sphere, the mother liquor water is filtered, the excess hydrogen ions and anions are washed away, and the cerium dioxide with a flower-ball-shaped structure formed by the agglomeration of layered cerium oxide can be obtained by drying.

[0021] Compared with the prior art, the preparation method of the present invention has the following beneficial effects:

[0022] 1) The preparation method of the present invention is simple to operate, has a short process flow, and eliminates the calcination process with high energy consumption in the traditional preparation process of cerium oxide powder. It is green and energy-saving, and is conducive to industrial production;

[0023] 2) The cerium oxide powder prepared by the preparation method of the present invention has a special microscopic morphology, which is a flower ball-shaped particle with a loose and porous surface;

[0024] 3) The preparation method of the present invention provides a new approach for preparing cerium oxide powder with special microscopic morphology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD pattern of the flower ball-shaped cerium oxide powder prepared in Example 1;

[0026] Figure 2 This is a SEM image of the flower ball-shaped cerium oxide powder described in Example 1;

[0027] Figure 3 This is a SEM image of the flower-spherical cerium oxide powder described in Example 2;

[0028] Figure 4 The SEM image of the product powder of Comparative Example 1;

[0029] Figure 5 This is the SEM image of the product powder described in Comparative Example 4. DETAILED DESCRIPTION

[0030] The present invention provides a method for preparing flower-spherical cerium oxide, comprising the following steps:

[0031] Mixing a soluble cerium salt solution and hydrogen peroxide, performing an oxidation precipitation reaction, and performing solid-liquid separation to obtain a solid product;

[0032] The solid product is washed and dried to obtain the flower ball-shaped cerium oxide;

[0033] The pH value of the soluble cerium salt solution is 2-4, the temperature of the oxidation precipitation reaction is 30-90°C, and the drying temperature is 30-90°C.

[0034] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0035] In the present invention, the pH of the soluble cerium salt solution is preferably 2.5 to 3.5. In an embodiment of the present invention, the pH of the soluble cerium salt solution may be 2, 2.5, 3, 3.5 or 4.

[0036] In the present invention, the concentration of the soluble cerium salt in the soluble cerium salt solution is preferably 0.5-2.5 mol / L, more preferably 1.0-2.0 mol / L. In an embodiment of the present invention, the concentration of the soluble cerium salt in the soluble cerium salt solution may be 2.5 mol / L, 1.2 mol / L or 0.5 mol / L.

[0037] In the present invention, the soluble cerium salt in the soluble cerium salt solution preferably includes cerium chloride and / or cerium nitrate. When the soluble cerium salt is cerium chloride and cerium nitrate, the present invention does not have any special restrictions on the ratio of the cerium chloride and cerium nitrate, and they can be mixed in any ratio. In an embodiment of the present invention, the soluble cerium salt can be cerium chloride or cerium nitrate.

[0038] In the present invention, the mass concentration of the hydrogen peroxide is preferably 10% to 50%, more preferably 30%.

[0039] In the present invention, the molar ratio of the soluble cerium salt to the hydrogen peroxide in the soluble cerium salt solution is preferably 1:(2-5), more preferably 1:(3-4). In an embodiment of the present invention, the molar ratio of the soluble cerium salt to the hydrogen peroxide may be 1:2, 1:4 or 1:5.

[0040] The present invention does not have any special limitation on the mixing process, and the mixing process may be carried out using a process well known to those skilled in the art.

[0041] In the present invention, the oxidation precipitation reaction is preferably carried out under stirring conditions, and the stirring speed is preferably 50-300 rpm, more preferably 100-200 rpm. In an embodiment of the present invention, the stirring speed can be 300 rpm, 150 rpm or 50 rpm.

[0042] In the present invention, the temperature of the oxidation precipitation reaction is 30-90°C, preferably 40-80°C, more preferably 50-70°C; the time is preferably 0.5-3h, more preferably 1-2h. In an embodiment of the present invention, the temperature of the oxidation precipitation reaction can be 30°C, 80°C or 90°C; the time of the oxidation precipitation reaction can be 0.5h, 1h or 3h.

[0043] In the present invention, the reaction formula of the oxidation precipitation reaction is: 2Ce 3+ +H2O2+6H2O→2Ce(OH)4↓+6H + ;Ce(OH)4→CeO2+2H2O.

[0044] After the oxidation precipitation reaction is completed, the present invention also preferably includes filtering, washing and drying in sequence; the present invention does not have any special restrictions on the filtering and washing processes, and can be carried out using processes well known to those skilled in the art. In the present invention, the drying temperature is 30-90°C, preferably 40-80°C, more preferably 50-70°C; the time is preferably 2-4h. In the present invention, the drying temperature can be 30°C, 80°C or 90°C; the time can be 6h, 4h or 2h.

[0045] In the present invention, the flower-ball-shaped cerium oxide is preferably a flower-ball-shaped structure formed by agglomeration of layered cerium oxide.

[0046] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] 3L of 2.5mol / L cerium chloride solution with a pH of 2 and 1.6L of 30% hydrogen peroxide solution were added into a reactor (the molar ratio of cerium chloride to hydrogen peroxide was 1:2), and the mixture was stirred at 300rpm and 30°C for 3h. The obtained precipitate was filtered, washed, and dried at 30°C for 6h to obtain a flower ball-shaped cerium oxide powder.

[0049] Figure 1 is the XRD diagram of the flower ball cerium oxide powder, Figure 1 It can be seen that the peak positions of the flower ball-shaped cerium oxide powder are 28°, 32°, 47°, 55°, 58° and 68° at 2θ, which are the same as the peak positions of the standard card, proving that the product of the present invention is cerium oxide;

[0050] Figure 2 is the SEM image of the flower ball-shaped cerium oxide powder, Figure 2 It can be seen that the flower-ball-shaped cerium oxide powder is a flower-ball-shaped structure formed by the aggregation of layered cerium oxide with loose and porous surfaces.

[0051] Example 2

[0052] 1.2L of 1mol / L, pH=2.5 cerium chloride solution and 0.5L of 30% hydrogen peroxide solution were added into a reactor (the molar ratio of cerium chloride to hydrogen peroxide was 1:4), and the mixture was stirred at 150rpm and reacted at 80℃ for 1h. The obtained precipitate was filtered, washed, and dried at 80℃ for 4h to obtain a flower ball-shaped cerium oxide powder.

[0053] Figure 3 is the SEM image of the flower ball-shaped cerium oxide powder, Figure 3 It can be seen that the flower-ball-shaped cerium oxide powder is a flower-ball-shaped structure formed by the aggregation of layered cerium oxide with loose and porous surfaces.

[0054] Example 3

[0055] 1L of 0.5mol / L cerium nitrate solution with a pH of 4 and 0.25L of 30% hydrogen peroxide solution were added into a reactor (the molar ratio of cerium chloride to hydrogen peroxide was 1:5), and the mixture was reacted at 90°C for 0.5h under stirring conditions of 50rpm. The obtained precipitate was filtered and washed, and then dried at 90°C for 2h to obtain flower-ball-shaped cerium oxide powder (the flower-ball-shaped cerium oxide powder is a lamellar spherical particle with a loose and porous surface).

[0056] Comparative Example 1

[0057] Refer to Example 1, except that the reaction was not stirred, the filtration was not washed, and the drying condition was 120°C. The product powder was obtained;

[0058] The product powder was subjected to SEM test, and the test results were as follows Figure 4 As shown by Figure 4 It can be seen that the product powder is an amorphous particle agglomerate.

[0059] Comparative Example 2

[0060] Referring to Example 1, the difference is that the pH of the cerium chloride solution is 0.2, the amount of hydrogen peroxide added is 0.5 L, and the amount of hydrogen peroxide in the hydrogen peroxide is 0.8 times the amount of cerium chloride. Under this condition, no precipitate is generated, mainly because the acidity of the reaction system is too high, and the hydrogen peroxide mainly reacts with hydrogen ions and does not participate in the oxidation of trivalent cerium.

[0061] Comparative Example 3

[0062] Refer to Example 1, except that the reaction temperature during the oxidation precipitation reaction is 20°C and the time is 20 minutes. Under this condition, no precipitate is generated.

[0063] Comparative Example 4

[0064] Refer to Example 2, except that the pH of the cerium chloride solution is 6.5, and a product powder is obtained.

[0065] The product powder was subjected to SEM test, and the test results were as follows Figure 5 As shown by Figure 5 It can be seen that the product powder is an amorphous particle agglomerate.

[0066] Comparative Example 5

[0067] Refer to Example 2, except that the reaction temperature is 100° C., a large amount of bubbles are generated during the reaction, and no obvious precipitate is produced.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing flower-spherical cerium oxide, characterized in that: It consists of the following steps: Mixing a soluble cerium salt solution and hydrogen peroxide, performing an oxidation precipitation reaction, and performing solid-liquid separation to obtain a solid product; The solid product is washed and dried to obtain the flower ball-shaped cerium oxide; The pH value of the soluble cerium salt solution is 2.5 to 3.5, the temperature of the oxidation precipitation reaction is 30 to 90 ° C, and the drying temperature is 30 to 90 ° C; The molar ratio of the soluble cerium salt and hydrogen peroxide in the soluble cerium salt solution is 1: (2 to 5); The oxidation precipitation reaction is carried out under stirring conditions.

2. The preparation method according to claim 1, characterized in that The soluble cerium salt in the soluble cerium salt solution includes cerium chloride and / or cerium nitrate.

3. The preparation method according to claim 2, characterized in that: The concentration of the soluble cerium salt in the soluble cerium salt solution is 0.5-2.5 mol / L.

4. The preparation method according to claim 1, characterized in that: The mass concentration of the hydrogen peroxide is 10-50%.

5. The preparation method according to claim 1, characterized in that: The stirring speed is 50-300 rpm.

6. The preparation method according to claim 1, characterized in that: The oxidation precipitation reaction time is 0.5~3h.

7. The preparation method according to claim 1, characterized in that: The drying time is 2 to 6 hours.

8. The preparation method according to claim 1, characterized in that: The flower ball-shaped cerium oxide is a flower ball-shaped structure formed by agglomeration of layered cerium oxide.

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