Cerium oxide-silicon oxide composite material as well as preparation method and application thereof

Abstract

The invention discloses a cerium oxide-silicon oxide composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) sequentially adding water-soluble cerium salt and polyvinylpyrrolidone into a mesoporous silica suspension to obtain a mixture; the mixture does not contain other water-soluble alkaline substances, and the other water-soluble alkaline substances are selected from one or more of metal hydroxide, ammonia water, ammonium salt, hexamethylenetetramine and urea; (2) reacting the mixture at 160-200 DEG C to obtain a precursor; and (3) roasting the precursor to obtain the cerium oxide-silicon oxide composite material. According to the method, alkaline substances such as metal hydroxide, ammonia water, ammonium salt, hexamethylenetetramine and urea do not need to be used in the preparation process, and the obtained composite material has good sphericity and dispersity.

Description

Technical Field

[0001] The present invention relates to a cerium oxide-silicon oxide composite material, a preparation method thereof, and uses thereof. Background Art

[0002] Cerium oxide has unique physical and chemical properties and is widely used in industrial catalysis, fuel cells, ceramics, electronic information, chemical mechanical polishing and other fields. As a cerium-based rare earth polishing material, cerium oxide has a high material removal rate and plays an irreplaceable role in polishing fields such as optical glass, semiconductor chips, and liquid crystal displays. However, due to the relatively active chemical properties of cerium oxide, strong surface adsorption, and easy agglomeration between particles, its dispersion performance is poor, and the morphology of cerium oxide particles is irregular and difficult to control, which is likely to cause defects such as scratches on the surface of polished devices in high-precision polishing processes, restricting its application and development in high-end polishing fields.

[0003] Silicon oxide as a polishing material has the advantages of high purity, good sphericity, uniform and controllable particles, stable polishing performance, and high polished surface quality. However, due to its large elastic modulus and low material removal rate of the polishing material, its industrial application is limited to a certain extent. Summary of the Invention

[0004] One object of the present invention is to provide a preparation method of a cerium oxide-silicon oxide composite material. This preparation method does not require the use of alkaline substances such as metal hydroxides, ammonia water, ammonium salts, hexamethylenetetramine, and urea, and the obtained composite material has good sphericity and dispersion. Further, cerium dioxide and silicon dioxide in the composite material prepared by this method are uniformly distributed. Another object of the present invention is to provide a cerium oxide-silicon oxide composite material. Still another object of the present invention is to provide uses of the above-mentioned cerium oxide-silicon oxide composite material.

[0005] The present invention realizes the above objects through the following technical solutions.

[0006] On the one hand, the present invention provides a preparation method of a cerium oxide-silicon oxide composite material, including the following steps:

[0007] (1) Sequentially adding a water-soluble cerium salt and polyvinylpyrrolidone to a mesoporous silicon oxide suspension to obtain a mixture; no other water-soluble alkaline substances are contained in the mixture, and the other water-soluble alkaline substances are selected from one or more of metal hydroxides, ammonia water, ammonium salts, hexamethylenetetramine, and urea;

[0008] (2) Reacting the mixture at 160-200 °C to obtain a precursor;

[0009] (3) Calcining the precursor to obtain a cerium oxide-silicon oxide composite material.

[0010] According to the preparation method of the present invention, preferably, other water-soluble basic substances are selected from one or more of water-soluble basic inorganic substances and water-soluble basic organic substances.

[0011] The mixture of the present invention does not contain other water-soluble basic substances. The mixture of the present invention reacts under the condition of the absence of other water-soluble basic substances to obtain a precursor.

[0012] The condition of not containing other water-soluble basic substances or the absence of other water-soluble basic substances means that except for mesoporous silica, water-soluble cerium salt, and polyvinylpyrrolidone, the other raw materials used do not contain water-soluble basic substances.

[0013] The metal hydroxide can be selected from alkali metal hydroxides and alkaline earth metal hydroxides. Examples of alkali metal hydroxides include but are not limited to potassium hydroxide and sodium hydroxide. Examples of alkaline earth metal oxides include but are not limited to calcium hydroxide and barium hydroxide.

[0014] Examples of ammonium salts include but are not limited to ammonium chloride, ammonium sulfate, ammonium bisulfate, ammonium nitrate, ammonium carbonate, and ammonium bicarbonate.

[0015] Preferably, the mixture is composed of mesoporous silica, water-soluble cerium salt, polyvinylpyrrolidone, and water.

[0016] The mixture of the present invention reacts under the condition of the absence of basic substances such as metal hydroxides, ammonia water, ammonium salts, hexamethylenetetramine, and urea. The obtained cerium oxide-silica composite material still has good sphericity and dispersibility. It helps to make cerium oxide and silica evenly distributed.

[0017] According to the preparation method of the present invention, preferably, the mesoporous silica is selected from one or more of SBA-15 and MCM-41.

[0018] More preferably, the mesoporous silica is SBA-15. This helps to improve the sphericity and dispersibility of the cerium oxide-silica composite material and helps to make cerium oxide and silica evenly distributed.

[0019] The BET specific surface area of the mesoporous silica of the present invention can be 350-800 m 2 / g; preferably 450-600 m 2 / g.

[0020] The pore diameter of the mesoporous silica of the present invention can be 3-15 nm; preferably 6-11 nm.

[0021] The pore volume of the mesoporous silica of the present invention can be 0.5-4 cm 3 / g; preferably 1-2 cm 3 / g.

[0022] This helps to improve the sphericity and dispersibility of the cerium oxide-silica composite material, and helps to make cerium oxide and silica evenly distributed.

[0023] According to the preparation method of the present invention, preferably, the mass ratio of mesoporous silica to water-soluble cerium salt is (0.01 - 0.55):1, and the mass ratio of polyvinylpyrrolidone to water-soluble cerium salt is (0.25 - 1.50):1.

[0024] The water-soluble cerium salt can be selected from one or more of cerium nitrate, cerium sulfate, and cerium chloride. According to an embodiment of the present invention, the water-soluble cerium salt is cerium nitrate. The water-soluble cerium salt can be used in the form of its hydrate.

[0025] The mass ratio of mesoporous silica to water-soluble cerium salt is (0.01 - 0.55):1; preferably (0.07 - 0.35):1.

[0026] The mass ratio of polyvinylpyrrolidone to water-soluble cerium salt is (0.25 - 1.50):1; preferably (0.4 - 1.20):1.

[0027] According to the preparation method of the present invention, preferably, the mixture is subjected to a hydrothermal reaction, and the reaction time is 16 - 24 h.

[0028] In step (2), the reaction temperature is 160 - 200 °C; preferably 170 - 190 °C.

[0029] In step (2), the reaction time can be 16 - 24 h; preferably 18 - 20 h.

[0030] The mixture can be reacted in a polytetrafluoroethylene reaction kettle.

[0031] The above reaction conditions help to improve the sphericity and dispersibility of the precursor, and make cerium oxide and silica evenly distributed.

[0032] In some embodiments, the following steps are further included: separating the solid and liquid of the reaction product obtained by the reaction to obtain a solid product. Washing the solid product, and then drying to obtain a precursor.

[0033] The reaction product can be separated by centrifugation or filtration. Preferably, centrifugation is used.

[0034] The purpose of washing is to wash away the impurities attached to the solid product. The washing method is not limited herein, and the conventional methods in the art can be used.

[0035] The purpose of drying is to remove the liquid attached to the surface of the washed solid product. The drying method is not limited herein, and the conventional methods in the art can be used.

[0036] According to the preparation method of the present invention, preferably, the concentration of the mesoporous silica suspension is 0.001 - 0.01 g / mL.

[0037] The concentration of the mesoporous silica suspension of the present invention can be 0.001 - 0.01 g / mL; preferably 0.003 - 0.0085 g / mL.

[0038] The solvent in the mesoporous silica suspension is water.

[0039] In some embodiments, it further includes the step of preparing the mesoporous silica suspension: ultrasonically dispersing mesoporous silica and water to obtain the mesoporous silica suspension.

[0040] The time for ultrasonic dispersion can be 10 - 60 min; preferably 20 - 40 min.

[0041] According to the preparation method of the present invention, preferably, under the condition of stirring, a water-soluble cerium salt and polyvinylpyrrolidone are sequentially added to the mesoporous silica suspension.

[0042] The rotation speed of the stirring device can be 400 - 1000 rpm; preferably 600 - 800 rpm. Mechanical stirring can be used for stirring.

[0043] In some embodiments, it further includes the following steps: after the addition of polyvinylpyrrolidone is completed, stir for 1 - 4 h, preferably stir for 2 - 3 h, to obtain a mixture.

[0044] According to the preparation method of the present invention, preferably, the calcination temperature is 600 - 1000 °C, and the calcination time is 1 - 4 h.

[0045] In the present invention, the calcination temperature can be 600 - 1000 °C; preferably 700 - 900 °C. This helps to improve the sphericity and dispersibility of the cerium oxide - silica composite material.

[0046] In the present invention, the calcination time can be 1 - 4 h; preferably 2 - 3 h.

[0047] Calcination can be carried out in a muffle furnace.

[0048] In some embodiments, it further includes the following steps: after the calcined product is cooled, grind it to obtain the cerium oxide - silica composite material.

[0049] Grinding disperses the particles of the calcined product that are partially adhered or agglomerated together, and does not change the shape and particle size of the calcined product particles.

[0050] On the other hand, the present invention provides a cerium oxide-silicon oxide composite material, which is prepared by the above preparation method.

[0051] The particle size of the cerium oxide-silicon oxide composite material of the present invention can be 100-800 nm. In some embodiments, the particle size of the cerium oxide-silicon oxide composite material is 200-700 nm. In other embodiments, the particle size of the cerium oxide-silicon oxide composite material can be greater than or equal to 300 nm. The particle size of the cerium oxide-silicon oxide composite material can be less than or equal to 400 nm.

[0052] The cerium oxide-silicon oxide composite material of the present invention is spherical.

[0053] In the cerium oxide-silicon oxide composite material of the present invention, cerium oxide and silicon oxide are uniformly distributed.

[0054] The cerium oxide-silicon oxide composite material of the present invention has a CeO 2 crystal structure.

[0055] On another aspect, the present invention provides the use of the above cerium oxide-silicon oxide composite material as a polishing material.

[0056] The cerium oxide-silicon oxide composite material of the present invention has good sphericity and dispersibility and can be used as a polishing material. The polishing material can be applied to the polishing of optical glass, semiconductor chips, liquid crystal displays, etc.

[0057] The preparation method of the present invention does not need to use alkaline substances such as metal hydroxides, ammonia water, ammonium salts, hexamethylenetetramine, urea, etc., and the obtained composite material has good sphericity and dispersibility. Further, cerium dioxide and silicon dioxide in the composite material prepared by this method are uniformly distributed. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 XRD pattern of the cerium oxide-silicon oxide composite material of Example 1.

[0059] Figure 2 SEM image of the cerium oxide-silicon oxide composite material of Example 1.

[0060] Figure 3 TEM image of the cerium oxide-silicon oxide composite material of Example 1.

[0061] Figure 4 SEM image of the cerium oxide-silicon oxide composite material of Example 2.

[0062] Figure 5 TEM image of the cerium oxide-silicon oxide composite material of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0063] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0064] The following is a description of the test method:

[0065] XRD: The test was carried out using an X'Pert PRO X-ray diffractometer. The sample was crushed into fine particles using a mortar, and an X'Pert PRO X-ray diffractometer was used with a Cu target and Kα radiation. The scanning speed was 2° per second, and the test angle range was 5 - 80° for analyzing the crystal structure of the sample.

[0066] SEM: The test was carried out using a ZEISS Sigma 500 field emission scanning electron microscope. The sample was placed in an anhydrous ethanol solution, ultrasonically dispersed for 5 min, then dropped onto a silicon wafer, dried, and sputter-coated with gold. The ZEISS Sigma 500 field emission scanning electron microscope was used to observe the microscopic morphology of the sample.

[0067] TEM: The test was carried out using a Thermo Fisher Talos F200i transmission electron microscope. The sample was placed in an anhydrous ethanol solution, ultrasonically dispersed for 5 min, then dropped onto a copper grid, dried, and the Thermo Fisher Talos F200i transmission electron microscope was used to observe the microscopic morphology and element distribution of the sample.

[0068] The following is a description of the raw materials:

[0069] Mesoporous silica SBA-15 was purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd. BET specific surface area: 450 - 600 m 2 / g, pore diameter: 6 - 11 nm, pore volume: 1 - 2 cm 3 / g.

[0070] Example 1

[0071] 0.2 g of mesoporous silica SBA-15 was placed in 60 mL of deionized water and ultrasonically dispersed for 30 min to obtain a mesoporous silica suspension.

[0072] Under stirring conditions at a rotation speed of 800 rpm, 2.17 g of cerium nitrate hexahydrate was added to the mesoporous silica suspension; after the cerium nitrate hexahydrate was dissolved, 1.09 g of polyvinylpyrrolidone was added; after the polyvinylpyrrolidone was added, stirring was continued for 2 h to obtain a mixture.

[0073] The mixture was reacted in a polytetrafluoroethylene reactor at 170 °C for 20 h to obtain a reaction product. The reaction product was centrifuged to obtain a solid product. The solid product was washed and then dried to obtain a precursor.

[0074] The precursor was placed in a muffle furnace and calcined at 700 °C for 2 h. After cooling, it was ground to obtain a cerium oxide-silicon oxide composite material.

[0075] Figure 1 This is the XRD pattern of the cerium oxide-silicon oxide composite material of this example. From Figure 1 it can be seen that its characteristic peaks are very sharp, indicating that the obtained cerium oxide-silicon oxide composite material has good crystallinity; and its XRD diffraction peaks correspond to the CeO 2 diffraction peaks identified by the standard PDF card JCPDS No. 34-0394, indicating that the addition of mesoporous silica does not affect the crystal structure of cerium oxide.

[0076] Figure 2 This is the SEM image of the cerium oxide-silicon oxide composite material of this example. From Figure 2 it can be seen that the cerium oxide-silicon oxide composite material prepared in this example has good sphericity, uniform particle size, a particle diameter of 200 - 400 nm, and good dispersibility.

[0077] Figure 3 This is the TEM image of the cerium oxide-silicon oxide composite material of this example. From Figure 3 it can be seen that the dispersibility between the cerium oxide-silicon oxide composite materials prepared in this example is good, the particle diameters are uniform, and from the surface scanning image, it can be seen that the oxygen element, silicon element, and cerium element are evenly distributed without segregation, indicating that cerium dioxide and silicon dioxide are evenly distributed in the cerium oxide-silicon oxide composite material.

[0078] Example 2

[0079] 0.5 g of mesoporous silica SBA-15 was placed in 60 mL of deionized water and ultrasonically dispersed for 30 min to obtain a mesoporous silica suspension.

[0080] Under the stirring condition with a rotation speed of 800 rpm, 2.17 g of cerium nitrate hexahydrate was added to the mesoporous silica suspension; after the cerium nitrate hexahydrate was dissolved, 2.17 g of polyvinylpyrrolidone was added; after the polyvinylpyrrolidone was added, stirring was continued for 2 h to obtain a mixture.

[0081] The mixture was reacted in a polytetrafluoroethylene reactor at 190 °C for 18 h to obtain a reaction product. The reaction product was centrifuged to obtain a solid product. The solid product was washed and then dried to obtain a precursor.

[0082] The precursor was placed in a muffle furnace, calcined at 900° C. for 3 h, and ground after cooling to obtain a cerium oxide-silicon oxide composite material.

[0083] Figure 4 is a SEM image of the cerium oxide-silicon oxide composite material of this embodiment. Figure 4 It can be seen that the cerium oxide-silicon oxide composite material prepared in this embodiment has good sphericity, uniform particle size, a particle diameter of 300-700 nm, and good dispersibility.

[0084] Figure 5 TEM image of the cerium oxide-silicon oxide composite material of this embodiment. Figure 5 It can be seen that the cerium oxide-silicon oxide composite material prepared in this embodiment has good dispersibility and uniform particle size, and from the surface scanning image, it can be seen that the oxygen element, silicon element and cerium element are evenly distributed without segregation, which indicates that cerium dioxide and silicon dioxide are evenly distributed in the cerium oxide-silicon oxide composite material.

[0085] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing a cerium oxide-silicon oxide composite material, characterized in that: The steps include: (1) adding a water-soluble cerium salt and polyvinyl pyrrolidone to a mesoporous silica suspension in sequence to obtain a mixture; the mixture does not contain other water-soluble alkaline substances, and the other water-soluble alkaline substances are selected from one or more of metal hydroxides, ammonia water, ammonium salts, hexamethylenetetramine, and urea; (2) reacting the mixture at 160-200° C. to obtain a precursor; (3) calcining the precursor to obtain a cerium oxide-silicon oxide composite material.

2. The preparation method according to claim 1, characterized in that: The other water-soluble alkaline substances are selected from one or more of water-soluble alkaline inorganic substances and water-soluble alkaline organic substances.

3. The preparation method according to claim 1, characterized in that: The mesoporous silica is selected from one or more of SBA-15 and MCM-41.

4. The preparation method according to claim 1, characterized in that: The mass ratio of mesoporous silica to water-soluble cerium salt is (0.01-0.55):1, and the mass ratio of polyvinyl pyrrolidone to water-soluble cerium salt is (0.25-1.50):

1.

5. The preparation method according to claim 1, characterized in that: The mixture is subjected to a hydrothermal reaction, and the reaction time is 16 to 24 hours.

6. The preparation method according to claim 1, characterized in that: The concentration of the mesoporous silica suspension is 0.001-0.01 g / mL.

7. The preparation method according to claim 1, characterized in that: The water-soluble cerium salt and polyvinyl pyrrolidone are sequentially added into the mesoporous silica suspension under stirring conditions.

8. The preparation method according to claim 1, characterized in that: The calcination temperature is 600-1000°C, and the calcination time is 1-4h.

9. A cerium oxide-silicon oxide composite material, characterized in that: The cerium oxide-silicon oxide composite material is obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the cerium oxide-silicon oxide composite material according to claim 9 as a polishing material.

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