A method for preparing metal oxide spherical particles with controllable size

Abstract

The application relates to a preparation method of metal oxide spherical particles with controllable size, and the specific steps are as follows: S1, metal nitrate and citric acid are added into deionized water and stirred until the mixture solution is clear; S2, an organic amine compound is slowly added into the mixture solution obtained in the step S1, and stirring is conducted until a viscous colloid is formed; S3, the viscous colloid obtained in the step S2 is added into a feeder of a spraying device, the viscous colloid is atomized into colloid particles by using a nozzle, and the colloid particles are sprayed into a flame to pyrolyze and form metal oxide spherical particles. Compared with the prior art, the raw materials are prepared into viscous colloid for spraying pyrolysis in the application, so that the structure damage caused by rapid loss of water in the spraying pyrolysis process is avoided; the process is simple, various process parameters of product preparation are convenient to control, and the oxide spherical particles can be directly generated by using the spraying pyrolysis, and a further sintering process is not needed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material science, in particular to a preparation method of metal oxide spherical particles with controllable size. BACKGROUND

[0002] Metal oxide spherical particles are larger particles formed by agglomeration of a large number of fine nanocrystalline grains in a certain way. Due to its macroscopic spherical characteristics, it has good dispersibility and flowability, etc., and is beneficial to uniform mixing with other materials in the preparation process of dispersion type composite materials, thereby improving the structural stability of the material. In addition, due to the existence of micro-nanocrystalline grains and structure inside, it also has certain reaction activity. It can be filled with materials or dispersed materials and is widely used in the fields of energy, catalysis, environmental protection, etc.

[0003] Hydrothermal / solvothermal method, vapor deposition method, sol-gel method, etc. are one of the effective ways to prepare oxide spherical particles, but for the products that can be produced on a large scale at present, the oxides of Ti, Si and Al are mainly used. However, the preparation technology of oxide spherical particles of transition metals and rare earths which are also important in the industrial field is lacking. Chinese invention patent CN105289433A provides a method for preparing NiCo2O4 microspheres based on a spray drying device. The method needs to first prepare microspheres by spray drying the precursor solution, and then calcine in a muffle furnace to form oxide products. However, due to the evaporation of water in the droplets during the spray drying process, the prepared products are mostly hollow or porous, which are prone to structural collapse during use. Chinese invention patent CN106629836B provides a preparation method of uranium oxide microspheres using microfluidic technology. The method adopts the way of complexing metal salt with organic base such as urea to form a solution, then dropping the solution into hot silicon oil to solidify, and finally sintering to form oxide microspheres. The prepared sample has high sphericity and good dispersibility. In recent years, many practitioners have used spray drying + calcination or sol-gel + calcination technology to prepare metal oxide spherical particles. However, at present, there is no report on the spray pyrolysis process using colloids as precursors. SUMMARY

[0004] The purpose of the present application is to overcome the defects of the prior art and provide a preparation method of metal oxide spherical particles with controllable size, which is simple and fast in process and can prepare metal oxide spherical particles with stable structure.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A preparation method of metal oxide spherical particles with controllable size, the specific steps are as follows:

[0007] S1, add metal nitrate and citric acid into deionized water and stir until clear to obtain a mixed solution;

[0008] S2, add organic amine compound into the mixed solution obtained in step S1 and stir until a viscous colloid is formed;

[0009] S3, add the viscous colloid obtained in step S2 into the feeder of a spraying device, atomize the viscous colloid into colloidal particles by using a nozzle, and spray the colloidal particles into a flame to pyrolyze and form metal oxide spherical particles.

[0010] Further, in step S1, the molar ratio of citric acid to metal nitrate is 0.5-1:1.

[0011] Further, in step S1, the metal contained in the metal nitrate is selected from any one of cerium, europium, samarium, and neodymium.

[0012] Further, in step S2, the amount of organic amine compound used is 3-8 wt% of the mixed solution.

[0013] Further, in step S2, the organic amine compound is selected from one or any combination of triethanolamine, mono-isopropanolamine, di-isopropanolamine, N,N-diethylethanolamine, diethylenetriamine, and triethylamine.

[0014] Further, in step S2, the organic amine compound is added to the mixed solution obtained in step S1 by using a peristaltic pump.

[0015] Further, in step S2, the stirring temperature is 85°C and the stirring time is 6h.

[0016] Further, in step S2, the stirring mode is mechanical stirring, the rotation speed is initially 50 rpm, slowly increased to 100 rpm within 50 minutes, and maintained at 100 rpm until the end of stirring.

[0017] Further, in step S3, the flame temperature is 700-1100°C, the flame gas is composed of methane and oxygen, and the flow rates are 0.65 L / min and 1.5 L / min, respectively.

[0018] Further, in step S3, the nozzle uses a pressure nozzle with a diameter of 0.75-3 mm.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] 1. Compared with the traditional solution spray pyrolysis method, the present application avoids the structure damage caused by the rapid loss of water during the spray pyrolysis process by preparing the raw material into a viscous colloid.

[0021] 2. Compared with the traditional solution spray pyrolysis method, the present application can form larger spherical particles during the spray process by preparing the raw material into a viscous colloid, and the size is controllable.

[0022] 3. The process adopted by the present application is simple, the process parameters of product preparation are convenient to control, and the oxide spherical particles can be directly generated by spray pyrolysis without further sintering process. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 SEM image of the overall morphology of the europium sesquioxide spherical particles obtained in Example 1;

[0024] Figure 2 SEM image of the surface morphology of the europium sesquioxide spherical particles obtained in Example 1;

[0025] Figure 3 SEM image of the cerium dioxide spherical particles obtained in Example 2;

[0026] Figure 4 SEM image of the cerium dioxide spherical particles obtained in Example 3;

[0027] Figure 5 SEM image of the cerium dioxide micro-powder obtained in Comparative Example 1. DETAILED DESCRIPTION

[0028] The present application will be described in detail below in combination with the drawings and specific examples.

[0029] A preparation method of metal oxide spherical particles with controllable size, the specific steps are as follows:

[0030] S1, metal nitrate and citric acid are added to deionized water and stirred until clear to obtain a mixed solution;

[0031] S2, an organic amine compound is added to the mixed solution obtained in step S1, and stirred until a viscous colloid is formed;

[0032] S3, the viscous colloid obtained in step S2 is added to the feeder of the spray device, the viscous colloid is atomized into colloid particles by the nozzle, and the colloid particles are sprayed into the flame to pyrolyze and form metal oxide spherical particles.

[0033] Further, in step S1, the molar ratio of citric acid to metal nitrate is 0.5-1:1.

[0034] Further, in step S1, the metal contained in the metal nitrate is selected from any one of cerium, europium, samarium, and neodymium.

[0035] Further, in step S2, the amount of the organic amine compound used is 3-8wt% of the organic amine compound in the mixed solution.

[0036] Further, in step S2, the organic amine compound is selected from one or any two combinations of triethanolamine, monoisopropanolamine, diisopropanolamine, N,N-diethylethanolamine, diethylenetriamine, and triethylamine.

[0037] Further, in step S2, the organic amine compound is added to the mixed solution obtained in step S1 by using a peristaltic pump.

[0038] Further, in step S2, the stirring temperature is 85°C, and the stirring time is 6h.

[0039] Further, in step S2, the stirring mode is mechanical stirring, the rotation speed is initially 50rpm, slowly increased to 100rpm within 50 minutes, and maintained at 100rpm until the end of stirring.

[0040] Further, in step S3, the flame temperature is 700-1100°C, the flame gas is composed of methane and oxygen, and the flow rates are 0.65L / min and 1.5L / min, respectively.

[0041] Further, in step S3, the nozzle uses a pressure nozzle with a diameter of 0.75-3mm.

[0042] The application will be further described below in conjunction with the accompanying drawings and specific examples.

[0043] Example 1

[0044] Reference Figures 1 to 2 A method for preparing metal oxide spherical particles with controllable size, the specific steps are as follows:

[0045] 1) 38.61g of europium nitrate hexahydrate and 21.01g of citric acid monohydrate were weighed with an analytical balance and dissolved in a round-bottom flask containing 150mL of deionized water, stirred for 1h to form a light pink solution.

[0046] 2) The light pink solution in the round-bottom flask obtained in step 1) was continuously stirred, and 13.2mL of diethylenetriamine was injected at a rate of 500μL·min -1The light pink solution obtained in step 1) was injected into a round-bottom flask at a rate of 500 μL·min

[0047] 3) The pink viscous colloid obtained in step 2) was placed in a spray pyrolysis device, and the pink viscous colloid was fed at a rate of 3 mL·min -1 through a nozzle with a diameter of 1.0 mm to form small droplets, which were sprayed into a high-temperature flame composed of methane and oxygen at flow rates of 0.65 L / min and 1.5 L / min, respectively, and the flame temperature was 900℃. When the pink viscous colloid contacted the flame, water evaporation, colloid thermal decomposition, and sintering occurred in sequence, and finally spherical europium sesquioxide particles were formed, wherein sintering refers to sintering of the colloid in the flame.

[0048] The overall morphology of the obtained spherical europium sesquioxide particles can be seen in FIG. 1. Figure 1 It can be seen that the product has good sphericity, and the diameter is about 100 μm.

[0049] The surface morphology of the obtained spherical europium sesquioxide particles can be seen in FIG. 2. Figure 2 It can be seen that the surface of the product is composed of fine particles with a diameter of about 100-200 nm, indicating that the colloid has good structural stability during spray pyrolysis.

[0050] Example 2:

[0051] Referring to Figure 3 , a method for preparing size-controllable metal oxide spherical particles, the specific steps are as follows:

[0052] 1) 40.22 g of cerium nitrate hexahydrate and 21.01 g of citric acid monohydrate were weighed with an analytical balance and dissolved in a round-bottom flask containing 150 mL of deionized water, and stirred for 1 h to form a light red solution.

[0053] 2) The light red solution in the round-bottom flask obtained in step 1) was continuously stirred, and a mixture of 6.2 mL of diethylene triamine and 5.3 mL of diisopropyl alcohol amine was injected into the light red solution obtained in step 1) at a rate of 500 μL·min -1 using a peristaltic pump, and the temperature of the solution was raised to 85℃ using a water bath device and stirring was continued for 6 h. During stirring, the speed was initially 50 rpm, slowly increased to 100 rpm within 50 minutes, and maintained until the end of the reaction, forming a red viscous colloid.

[0054] 3) The red viscous gel obtained in step 2) was placed in a spray pyrolysis device, the red viscous gel feed was atomized into small droplets by a nozzle with a diameter of 0.75 mm at a feed rate of 3 mL min -1 , and sprayed into a high-temperature flame, the flame gas was composed of methane and oxygen, the flow rates were 0.65 L / min and 1.5 L / min, respectively, the flame temperature was 900 °C, when the red viscous gel contacted the flame, water evaporation, gel thermal decomposition, sintering and forming occurred in sequence, and finally spherical ceria particles were formed, wherein sintering and forming refers to sintering of the gel in the flame.

[0055] The morphology of the obtained spherical ceria particles can be seen in Figure 3 , it can be seen that the product is aggregated by fine microspheres into spherical particles, and the diameter of the spherical particles is about 10-25 μm.

[0056] Example 3:

[0057] Referring to Figure 4 , the difference between this embodiment and Example 2 is that the organic amine injected by the peristaltic pump in step 2) is 13.7 mL of diisopropanolamine. The diameter of the atomizing nozzle in step 2) is 1.3 mm. The specific steps are as follows:

[0058] 1) 40.22 g of cerium nitrate hexahydrate and 21.01 g of citric acid monohydrate were weighed with an analytical balance and dissolved in a round-bottom flask containing 150 mL of deionized water, stirred for 1 h to form a reddish solution.

[0059] 2) The reddish solution in the round-bottom flask obtained in step 1) was continuously stirred, and a mixture of 6.2 mL of diethylene triamine and 5.3 mL of diisopropanolamine was injected into the reddish solution obtained in step 1) by a peristaltic pump at a rate of 500 μL min -1 , the temperature of the solution was raised to 85 °C by a water bath device and stirring was continued for 6 h, wherein the stirring speed was increased from the initial 50 rpm to 100 rpm slowly within 50 minutes and maintained until the end of the reaction, forming a red viscous gel.

[0060] 3) The red viscous gel obtained in step 2) was placed in a spray pyrolysis device, the red viscous gel feed was atomized into small droplets by a nozzle with a diameter of 1.3 mm at a feed rate of 3 mL min -1 , and sprayed into a high-temperature flame, the flame gas was composed of methane and oxygen, the flow rates were 0.65 L / min and 1.5 L / min, respectively, the flame temperature was 900 °C, when the red viscous gel contacted the flame, water evaporation, gel thermal decomposition, sintering and forming occurred in sequence, and finally spherical ceria particles were formed, wherein sintering and forming refers to sintering of the gel in the flame.

[0061] The morphology of the obtained spherical ceria particles can be seen in Figure 4 It can be seen that the product has a diameter of about 180-200 μm.

[0062] Comparative Example 1

[0063] Reference Figure 5 The difference between the present comparative example 1 and the examples is that the spray pyrolysis process uses a solution as the precursor, and the specific steps are as follows:

[0064] 1) 40.22 g of cerium nitrate hexahydrate and 21.01 g of citric acid monohydrate were weighed using an analytical balance and dissolved in a round-bottom flask containing 150 mL of deionized water, and stirred for 1 h to form a reddish solution.

[0065] 2) The reddish solution obtained in step 1) was placed in a spray pyrolysis device, and the colloidal feed was atomized into small droplets by a nozzle with a diameter of 1 mm at a feed rate of 3 mL·min -1 The flame gas was composed of methane and oxygen, and the flow rates were 0.65 L / min and 1.5 L / min, respectively. The flame temperature was 900℃. When the droplets contacted the flame, instantaneous water evaporation and metal salt thermal decomposition occurred, and sintering was formed, finally forming fine ceria micropowder.

[0066] The morphology of the obtained ceria can be seen in Figure 5 It can be seen that the product is fine irregular micropowder.

[0067] The present application uses a colloid formed from metal nitrate, citric acid and organic amine for spray pyrolysis, which can quickly produce metal oxide spherical particles with controllable size. Compared with comparative example 1, using a colloid for spray pyrolysis can avoid structural damage caused by rapid loss of water. The process of the present application is simple, and the process parameters are easy to control. The product generated by spray pyrolysis does not need to be further sintered.

[0068] The above description of the examples is for the convenience of those of ordinary skill in the art to understand and use the present application. Those skilled in the art can easily make various modifications to these examples, and apply the general principles described herein to other examples without having to undergo creative labor. Therefore, the present application is not limited to the above examples, and those skilled in the art can make improvements and modifications within the scope of the present application without departing from the scope of the present application.

Claims

1. A method for producing metal oxide spheroidal particles of controlled size, characterized by, The specific steps are as follows: S1, metal nitrate, citric acid is added to deionized water and stirred until clear to obtain a mixed solution; S2, the organic amine compound is added to the mixed solution obtained in step S1, and stirred until a viscous gel is formed; S3, the viscous gel obtained in step S2 is added to the feeder of the spray device, the viscous gel is atomized into colloidal particles by the nozzle, and the colloidal particles are sprayed into the flame to pyrolyze the metal oxide spherical particles; In step S1, the metal contained in the metal nitrate is selected from any one of cerium, europium, samarium, and neodymium; In step S2, the organic amine compound is selected from one or any two combinations of triethanolamine, monoisopropanolamine, diisopropanolamine, N,N-diethylethanolamine, diethylenetriamine, and triethylamine; In step S3, the nozzle uses a pressure nozzle with a diameter of 0.75-3 mm; When the metal nitrate is europium nitrate and the organic amine compound is diethylenetriamine, the diameter of the europium oxide spherical particles is 100 μm; When the metal nitrate is cerium nitrate and the organic amine compound is diethylenetriamine and diisopropanolamine, the diameter of the cerium dioxide particles is 10-25 μm; When the metal nitrate is cerium nitrate and the organic amine compound is diisopropanolamine, the diameter of the cerium dioxide particles is 180-200 μm.

2. The method for preparing size-controllable spherical metal oxide particles according to claim 1, characterized in that, In step S1, the molar ratio of citric acid to metal nitrate is 0.5-1:

1.

3. The method for preparing size-controllable spherical metal oxide particles according to claim 1, characterized in that, In step S2, the amount of organic amine compound used is 3-8 wt% of the mixed solution.

4. The method of claim 1, wherein the metal oxide particles are spherical particles having a diameter of 1 to 100 nm. In step S2, the organic amine compound is added by using a peristaltic pump to inject into the mixed solution obtained in step S1.

5. The method of claim 1, wherein the metal oxide particles are spherical particles having a diameter of 1 to 100 nm. In step S2, the stirring temperature is 85 ℃, and the stirring time is 6 h.

6. The method of claim 1, wherein the metal oxide particles have a size distribution of 0.1 to 10 μm. In step S2, the stirring method is mechanical stirring, the speed is initially 50 rpm, which is slowly increased to 100 rpm within 50 minutes, and the speed is kept at 100 rpm until the end of stirring.

7. The method of claim 1, wherein the metal oxide particles have a diameter of 1 to 100 nm. In step S3, the flame temperature is 700-1100 ℃, and the flame gas is composed of methane and oxygen.

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