Cerium-based oxide material and preparation method of precursor thereof

文档序号：430596 发布日期：2021-12-24 浏览：25次中文

阅读说明：本技术 铈基氧化物材料及其前驱体的制备方法 (Cerium-based oxide material and preparation method of precursor thereof ) 是由李永绣丁林敏李静周雪珍王学亮潘望好刘艳珠李东平于 2021-10-22 设计创作，主要内容包括：本发明涉及一种铈基氧化物材料的制备方法,该制备方法包括如下步骤：配制以铈为主的稀土料液；将沉淀剂溶液与该稀土料液混合,形成稀土沉淀,该沉淀剂溶液为碳酸氢铵和碳酸铵中的任意一种或两种溶液；将稀土沉淀陈化结晶；对陈化结晶后的稀土沉淀进行洗涤、过滤、干燥,以得到铈基前驱体化合物；煅烧该铈基前驱体化合物,得到铈基氧化物。本方法可以通过调控沉淀反应和陈化结晶过程温度和时间来调控铈基氧化物前驱体的形貌,从而形成针形聚集状(类扫帚状)的前驱体。(The invention relates to a preparation method of a cerium-based oxide material, which comprises the following steps: preparing rare earth feed liquid mainly containing cerium; mixing a precipitant solution with the rare earth feed liquid to form rare earth precipitate, wherein the precipitant solution is any one or two of ammonium bicarbonate and ammonium carbonate; precipitating, aging and crystallizing rare earth; washing, filtering and drying the aged and crystallized rare earth precipitate to obtain a cerium-based precursor compound; the cerium-based precursor compound is calcined to obtain a cerium-based oxide. The method can regulate the shape of the cerium-based oxide precursor by regulating and controlling the temperature and time of the precipitation reaction and the aging crystallization process, thereby forming the needle-shaped aggregated (broom-like) precursor.)

1. A method for preparing a cerium-based oxide material, comprising the steps of:

preparing rare earth feed liquid mainly containing cerium;

mixing a precipitant solution with the rare earth feed liquid to form rare earth precipitate, wherein the precipitant solution is one or two of ammonium bicarbonate and ammonium carbonate, the precipitation feed ratio is greater than or equal to 6, and the precipitation feed ratio refers to HCO₃ ^-And Ce³⁺Or CO₃ ^2-And Ce³⁺The molar ratio of (A) to (B);

precipitating, aging and crystallizing rare earth;

washing, filtering and drying the aged and crystallized rare earth precipitate to obtain a cerium-based precursor compound;

the cerium-based precursor compound is calcined to obtain a cerium-based oxide.

2. The method for preparing a cerium-based oxide material according to claim 1, wherein at least one of the following conditions a-i is satisfied:

a. mixing the precipitant solution with the rare earth feed liquid at 10-70 deg.C;

b. the mixing of the precipitant solution and the rare earth feed liquid is carried out under the stirring condition;

c. the concentration of the rare earth feed liquid is 0.5-1.4 mol/L;

d. aging and crystallizing the rare earth precipitate at 50-70 ℃;

e. the aging crystallization time is more than 12 h;

f. when washing the rare earth precipitate, until the eluate is free of chloride ions;

g. the calcination temperature is 400-1200 ℃;

h. the calcination time is 2-4 h;

i. the feeding ratio of the precipitate is 6-8.

3. The method for preparing a cerium-based oxide material as claimed in claim 2, wherein the calcination temperature is 600-1300 ℃.

4. The method for preparing a cerium-based oxide material according to claim 2, wherein the calcination temperature is 1000 ℃.

5. The method for preparing a cerium-based oxide material as claimed in claim 2, wherein the calcination temperature is 800-1000 ℃.

6. The method of claim 1, wherein the rare earth feed solution comprises a chloride or nitrate solution of one or more of cerium, lanthanum, praseodymium, yttrium, samarium, gadolinium.

7. A method for preparing a cerium-based oxide precursor, comprising the steps of:

preparing rare earth feed liquid mainly containing cerium;

mixing a precipitant solution with the rare earth feed liquid to form rare earth precipitate, wherein the precipitant solution is any one or two of ammonium bicarbonate and ammonium carbonate;

aging and crystallizing the rare earth precipitate;

and washing, filtering and drying the aged and crystallized rare earth precipitate to obtain a cerium-based oxide precursor compound.

8. The method for preparing a cerium-based oxide material according to claim 7, wherein at least one of the following conditions a to g is satisfied:

a. mixing the precipitant and the rare earth feed liquid at 10-70 deg.C;

b. mixing the precipitant solution with the rare earth feed liquid under stirring;

c. the concentration of the rare earth feed liquid is 0.5-1.4 mol/L;

d. aging and crystallizing at 50-70 deg.C;

e. the aging crystallization time is more than 12 h;

f. when washing the rare earth precipitate, until the eluate is free of chloride ions;

g. the feeding ratio of the precipitate is 6-8.

Technical Field

The invention discloses a preparation method of a cerium-based oxide material, belonging to the technical field of rare earth material preparation.

Background

Cerium oxide, which is representative of light rare earth materials, is an important rare earth oxide due to its remarkable redox properties and easy passage of Ce³⁺And Ce⁴⁺The transition between oxidation states is of great interest to obtain a very good oxygen storage and release capacity (OSC). The cerium oxide can be combined with a plurality of other materials, and has wide application in the aspects of catalysts, solid oxide fuel cells, biomedical sensors, polishing materials, solar cells, ultraviolet blocking materials and the like. For example, a graphene (CeO) modified with cerium oxide₂@ G), fixing polysulfide through the strong chemical adsorption of nano cerium oxide particles, and enhancing sulfur redox reaction through the high electrocatalytic activity of the polysulfide; while the highly conductive graphene sheets serve as upper current collectors to improve electron/ion conductivity and facilitate reuse of sulfur species. Such CeO₂The Li-S battery with the @ G modified diaphragm has high specific capacity (0.2A G)^-11546mAh g^-1)Excellent rate capability (3A g)^-1The average value is 861mAh g^-1) And long term cycling durability (5A g after 1000 cycles)^-1The time is 480mAh g^-1). Cerium oxide and rare earth (lanthanum, praseodymium and neodymium) metal doped cerium dioxide nano-catalyst synthesized by citric acid assisted sol-gel method are adopted to decompose hydrogen iodide in hydrogen production cycle by decomposing sulfur and iodine with thermochemical water. Doping of other rare earths results in an increase in specific surface area, thermal stability and oxygen vacancy concentration. Wherein the lanthanum-doped cerium oxide material shows the microcrystals with the highest specific surface area, thermal stability, oxygen vacancy concentration and minimumSize and highest catalytic activity for decomposition of hydrogen iodide.

Chemical Mechanical Polishing (CMP) is widely used in the fields of optical glass, integrated circuits, etc. as a global surface planarization technology developed in recent decades. The abrasive particles in the polishing slurry are critical to achieve chemical and mechanical action during the polishing process. The abrasive particles commonly used at present are mainly CeO₂、Al₂O₃、SiO₂. SiO among three kinds of abrasive particles₂The chemical property is stable, the oxidation is slow when the chemical reaction is carried out with the surface of the workpiece, and meanwhile, the silica sol generated by the chemical reaction is not easy to remove and easily pollutes the surface of the workpiece. Al (Al)₂O₃The hardness is high, the defects such as scratches and the like are easily generated on the surface of a workpiece, the sample is easy to agglomerate, and the selectivity is poor. Thus SiO₂、Al₂O₃CeO is only used in the processing of some workpieces with high hardness and low processing precision requirement₂Compared with the two grinding materials, the two grinding materials have moderate hardness, can avoid surface damage in the polishing process in use, and have strong oxidation activity, good recycling property and higher polishing rate. Thus CeO₂As abrasive particles, they have been widely studied in the development of polishing powders.

The performance of the cerium-based rare earth oxide polishing material is closely related to the particle size and morphology, particle size distribution, surface characteristics, suspension property and the like of the cerium-based rare earth oxide polishing material, so that the surface smoothness of a polished workpiece is influenced. Therefore, there is a need to tune the performance of synthetic polishing powders by innovations in the synthesis process or doping of other rare earth elements. For example: wenxingmu et al synthesized CeO with a sphere-like structure with a particle size of 20nm by a solvothermal method₂The polishing powder can obtain a high polishing rate and an ultra-flat polished surface when being used for processing the surface of a single crystal silicon. The result shows that the contact form of the nano cerium oxide square block and the silicon wafer is mainly surface contact, and generates less scratches; because the contact form of the nano cerium oxide octahedron and the silicon wafer is mainly point contact, serious scratches can be generated. Thus, sodiumThe polishing efficiency and quality of the cerium oxide have a great relationship with the morphology thereof.

At present, the synthesis of cerium dioxide with controllable morphology mostly adopts a solvothermal method, the synthesis condition is severer, high temperature and high pressure are needed, the synthesis yield is less, and the method is not beneficial to industrial production. Based on the inheritance of particle morphology in the process of calcining the cerium-based precursor compound to the cerium-based oxide, the method for synthesizing the cerium-based precursor compound and then calcining the cerium-based precursor compound to obtain the cerium-based oxide is a feasible way. This requires controlled synthesis of particle size and morphology during synthesis of the precursor. The synthesis method of the crystal form cerium carbonate mainly comprises a homogeneous precipitation method, a hydrothermal growth method and hydroxide-CO₂And carbonate precipitation crystallization. Among them, the carbonate precipitation crystallization method has been widely studied because of its simplicity in operation, low cost and easiness in industrialization. However, the precipitation crystallization process is influenced by both thermodynamics and kinetics, and the morphology, particle size, specific surface area and other properties of rare earth carbonate are influenced by many factors such as temperature, pH, charging ratio, aging time, impurity ions, additives and the like. Therefore, the precipitation crystallization process of rare earth carbonate and the chemical property index control technology thereof are hot spots and difficulties of domestic and foreign research.

There have been many reports on the precipitation and crystallization methods of rare earth carbonate. Based on the research result of the crystallization process mechanism of rare earth carbonate, Nanchang university provides some technical methods for realizing rapid crystallization or controlling particle size and chloride content. For example, Zhuwei, Qiouxing, etc. have studied NH₄HCO₃And Y (NO)₃)₃Reaction to form Y₂(CO₃)₃The crystal growth mechanism and the grain size control method of the precipitate in the aging crystallization process can adjust the crystal phase, the appearance and the grain size of the precipitate by controlling the aging time and the temperature. The structure of the crystal is transformed from amorphous to water rhombohedral yttrium crystal, and the morphology is transformed from nano spherical small particles to dumbbell, bird nest and large particle spheres, so that the small particles (D) can be prepared₅₀<1 μm) and large particles Y₂O₃Micro-nano structure aggregate (D)₅₀>30 μm). An Ji WeiThe electronic science and technology company Limited adopts cerium stock solution to react with a precipitator, 100nm-300nm spherical cerium carbonate precursor with uniform particle size distribution is synthesized by controlling a plurality of conditions such as the molar ratio of reaction materials, the concentration of reactants, the feeding time, the synthesis temperature and time, bubbling treatment of the reaction stock solution by inert gas and the like, and spherical cerium oxide is obtained by calcination and has good CMP polishing performance after being dispersed.

At present, cerium carbonate precursors with various shapes such as flake, spindle, sphere, flower and the like are synthesized by controlling a precipitation crystallization process by adopting a carbonate precipitation method. However, the cerium-based oxide obtained by calcination is difficult to wash and separate liquid and solid, and it is difficult to obtain a product having a high purity.

Disclosure of Invention

Therefore, in view of the above-mentioned problems, it is an object of the present invention to provide a method for preparing a cerium-based oxide material, which is simple in steps and can obtain a high-purity cerium-based oxide.

A method for preparing a cerium-based oxide material, comprising the steps of:

preparing rare earth feed liquid mainly containing cerium;

precipitating, aging and crystallizing rare earth;

washing, filtering and drying the aged and crystallized rare earth precipitate to obtain a cerium-based precursor compound;

the cerium-based precursor compound is calcined to obtain a cerium-based oxide.

Preferably, at least one of the following conditions a-i is satisfied:

a. mixing the precipitant solution with the rare earth feed liquid at 10-70 deg.C;

b. the mixing of the precipitant solution and the rare earth feed liquid is carried out under the stirring condition;

c. the concentration of the rare earth feed liquid is 0.5-1.4 mol/L;

d. aging and crystallizing the rare earth precipitate at 50-70 ℃;

e. the aging crystallization time is more than 12 h;

f. when washing the rare earth precipitate, until the eluate is free of chloride ions;

g. the calcination temperature is 400-1200 ℃;

h. the calcination time is 2-4 h;

i. the feeding ratio of the precipitate is 6-8.

Preferably, the calcination temperature is 600-.

Preferably, the calcination temperature is 1000 ℃.

Preferably, the calcination temperature is 800-1000 ℃.

Preferably, the rare earth feed liquid contains chloride or nitrate solution of one or more of cerium, lanthanum, praseodymium, yttrium, samarium and gadolinium.

The invention also provides a preparation method of the cerium-based oxide precursor, which comprises the following steps:

preparing rare earth feed liquid mainly containing cerium;

mixing a precipitant solution with the rare earth feed liquid to form rare earth precipitate, wherein the precipitant solution is any one or two of ammonium bicarbonate and ammonium carbonate;

aging and crystallizing the rare earth precipitate;

and washing, filtering and drying the aged and crystallized rare earth precipitate to obtain a cerium-based oxide precursor compound.

Preferably, at least one of the following conditions a-f is satisfied:

a. mixing the precipitant and the rare earth feed liquid at 10-70 deg.C;

b. mixing the precipitant solution with the rare earth feed liquid under stirring;

c. the concentration of the rare earth feed liquid is 0.5-1.4 mol/L;

d. aging and crystallizing at 50-70 deg.C;

e. the aging crystallization time is more than 12 h;

f. when washing the rare earth precipitate, until the eluate is free of chloride ions;

g. the feeding ratio of the precipitate is 6-8.

Compared with the prior art for producing the cerium carbonate, the invention has the innovation point that the shape of the cerium-based oxide precursor can be regulated and controlled by regulating and controlling the temperature and time of the precipitation reaction and the aging crystallization process, thereby forming the needle-shaped aggregated (broom-like) precursor. The cerium-based precursor compound includes a plurality of strip-shaped single crystals which are cross-grown and aggregated, and which can float in water, thereby facilitating washing and liquid-solid separation and obtaining a high-purity product. The cerium-based rare earth oxide obtained by calcining at a not too high temperature has the same shape as the precursor; when the single crystal is calcined at a higher temperature, the strip single crystal is converted into a small-particle beaded shape, is easily dispersed into spheroidal fine particles, and shows higher polishing and catalytic properties. The broom-like product can be obtained by doping light rare earth such as lanthanum, praseodymium, neodymium and the like. Therefore, cerium-based rare earth oxide materials of various compositions can be prepared.

In particular, when a higher aging temperature and a longer aging time are adopted, a cerium-based rare earth carbonate precursor with a special composition and a special morphology can be formed, and the cerium-based oxide with excellent polishing and catalytic performances is obtained by calcining. In the mechanism research, the characteristic is found to be associated with the valence change characteristic of cerium. Due to the valence-changing nature of 3+/4+, precursors of this morphology are formed. In addition, the precursor compounds formed were composed of carbonates and oxalates of cerium, indicating that oxalate formation during precipitation crystallization was caused by the oxidation-reduction properties of cerium, a particular reaction we first discovered.

The method adopts a simple ammonium bicarbonate precipitation method, and realizes the synthesis of the needle-shaped aggregated cerium-based precursor compound by controlling the reaction charging proportion, the aging temperature and the time. In the washing process, the method is beneficial to the washing of chlorine radicals and the solid-liquid separation, and then the broom-shaped cerium-based oxide material assembled by small granular beads is obtained by calcination. Compared with hydrothermal synthesis, the method has the advantages of simpler synthesis conditions, high yield and more contribution to industrial production.

Drawings

FIG. 1 is an electron micrograph of a cerium-based precursor compound obtained in example 1.

FIG. 2 is an electron micrograph of the cerium-based precursor compound obtained in example 2.

FIG. 3 is an electron micrograph of a cerium-based precursor compound obtained in example 3

FIG. 4 is an electron micrograph of the cerium-based precursor obtained in example 4

FIG. 5 is an electron micrograph of cerium-based precursors sampled at different aging times of example 4

FIG. 6 is an XRD pattern of a cerium-based precursor obtained in example 5

FIG. 7 is a thermogram of the cerium-based precursor obtained in example 5

FIG. 8 is an electron micrograph of ceria obtained by calcination at different temperatures in example 5.

FIG. 9 is an XRD pattern of ceria obtained by calcination at different temperatures in example 5.

FIG. 10 is a TEM image of the cerium oxide calcined at 400 ℃ and 900 ℃ in example 5.

FIG. 11 is an electron micrograph of lanthanum and yttrium precursors alone in example 6

FIG. 12 is an electron micrograph of a lanthanum-doped cerium-based precursor compound obtained in example 7

FIG. 13 is an XRD pattern of a sample obtained by calcining the lanthanum-doped cerium-based precursor at 850 ℃ in example 7

FIG. 14 is an electron micrograph of a praseodymium-doped cerium-based precursor compound of example 8

FIG. 15 is an XRD pattern of a sample obtained by calcining the praseodymium-doped cerium-based precursor compound of example 8 at 850 deg.C

FIG. 16 is an electron micrograph of a yttrium-doped cerium-based precursor compound of example 9

FIG. 17 is an electron micrograph of a terbium-doped cerium-based precursor compound of example 10

FIG. 18 shows the removal rate of the ceria powder obtained in example 11 for ZF7 glass polishing at different calcination temperatures.

FIG. 19 is a graph showing the pH-dependent polishing efficiency of the ceria powder obtained in example 11 for ZF7 glass at different calcination temperatures.

FIG. 20 is a graph showing the potential change of the ceria powder obtained in example 11 at different calcination temperatures against ZF7 glass polishing.

FIG. 21 is a graph showing the change in removal rate of continuous polishing at the optimum temperature point for 6h in example 12.

FIG. 22 is a graph showing the change in the decoloring rate of different cerium oxide contents in example 13 for methylene blue dye under illumination conditions

FIG. 23 is a graph showing the change in the bleaching ratio of the obtained cerium oxide to methylene blue dye under light conditions at different temperatures in example 14.

Table 1 shows the specific surface area and the crystal grain size of the cerium oxide calcined at different temperatures in example 3.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

A method for preparing a cerium-based oxide material, comprising the steps of:

preparing rare earth feed liquid mainly containing cerium;

mixing the precipitant solution with the rare earth material liquid to obtain the final productForming rare earth precipitate, wherein the precipitant solution is one or two of ammonium bicarbonate and ammonium carbonate, the precipitation charge ratio is greater than or equal to 6, and the precipitation charge ratio refers to HCO₃ ^-And Ce³⁺Or CO₃ ^2-And Ce³⁺The molar ratio of (A) to (B);

precipitating, aging and crystallizing rare earth;

washing, filtering and drying the aged and crystallized rare earth precipitate to obtain a cerium-based precursor compound;

the cerium-based precursor compound is calcined to obtain a cerium-based oxide.

Preferably, at least one of the following conditions a-i is satisfied:

a. mixing the precipitant solution with the rare earth feed liquid at 10-70 deg.C;

b. the mixing of the precipitant solution and the rare earth feed liquid is carried out under the stirring condition;

c. the concentration of the rare earth feed liquid is 0.5-1.4 mol/L;

d. aging and crystallizing the rare earth precipitate at 50-70 ℃;

e. the aging crystallization time is more than 12 h;

f. when washing the rare earth precipitate, until the eluate is free of chloride ions;

g. the calcination temperature is 400-1200 ℃;

h. the calcination time is 2-4 h;

i. the feeding ratio of the precipitate is 6-8.

Preferably, the calcination temperature is 600-.

Preferably, the calcination temperature is 1000 ℃.

Preferably, the calcination temperature is 800-1000 ℃.

Preferably, the rare earth feed liquid contains chloride or nitrate solution of one or more of cerium, lanthanum, praseodymium, yttrium, samarium and gadolinium.

The invention also provides a preparation method of the cerium-based oxide precursor, which comprises the following steps:

preparing rare earth feed liquid mainly containing cerium;

mixing a precipitant solution with the rare earth feed liquid to form rare earth precipitate, wherein the precipitant solution is any one or two of ammonium bicarbonate and ammonium carbonate;

aging and crystallizing the rare earth precipitate;

and washing, filtering and drying the aged and crystallized rare earth precipitate to obtain a cerium-based oxide precursor compound.

Preferably, at least one of the following conditions a-f is satisfied:

a. mixing the precipitant and the rare earth feed liquid at 10-70 deg.C;

b. mixing the precipitant solution with the rare earth feed liquid under stirring;

c. the concentration of the rare earth feed liquid is 0.5-1.4 mol/L;

d. aging and crystallizing at 50-70 deg.C;

e. the aging crystallization time is more than 12 h;

f. when washing the rare earth precipitate, until the eluate is free of chloride ions;

g. the feeding ratio of the precipitate is 6-8.

The cerium-based oxide obtained by this method is useful as a polishing material, a catalytic material, an electrode material, and the like. When the polishing powder is used as polishing powder, the optimal calcination temperature is about 1000 ℃, and the polishing powder is prepared into slurry with 0.5 to 5 percent of solid content for use. When used as a catalytic material, the catalytic activity increases as the calcination temperature increases from 800 ℃ to 1000 ℃.

To demonstrate the polishing effect of the synthesized product, the prepared cerium-based oxide polishing powder was prepared as a polishing solution having a solid content of 1%, ZF7 glass was polished using a Unipol 802 type precision lapping and polishing machine (shenyang family crystal), and the Material Removal Rate (MRR) was calculated according to the following formula.

MRR is the material removal rate in nm/min, Δ m is the workpiece mass difference (g) before and after polishing, and ρ is the density of ZF7 glass 2.51g/cm³S contact area (cm) of the workpiece to be polished²) And t is polishing time (min).

In order to demonstrate the catalytic performance of the synthesized products, they were used to catalyze the photocatalytic degradation performance of methylene blue, rhodamine and methyl orange. The specific method comprises the following steps: adding a certain amount of the prepared cerium-based oxide into 30mL of prepared dye solution, carrying out ultrasonic treatment in a dark place for 5min, stirring for 30min to reach adsorption and desorption balance, then irradiating for 2h under a xenon lamp light source, then centrifuging, and measuring the absorbance of the mixture by using a TU-1810 ultraviolet spectrophotometer. The decolorization ratio of the dye was calculated according to the following formula.

A0 is the initial absorbance (Abs) of the dye, and A is the absorbance (Abs) measured after 2h of dye illumination.

Example 1

1.4mol/L of CeCl is taken₃Adding 30ml of the feed liquid into a beaker according to a set precipitation feed ratio [ HCO ]₃ ^-:Ce³⁺]＝3[HCO₃ ^-:Ce³⁺]＝6，[HCO₃ ^-:Ce³⁺]125mL, 250mL, 336mL ammonium bicarbonate solutions were measured, added to the CeCl-containing solution at a constant flow rate₃In the beaker of the feed liquid, white precipitation can be observed to occur immediately in the solution, and a large amount of bubbles are generated, after the precipitation reaction is fully completed, the beaker is sealed and put in a water bath kettle at 60 ℃ for aging. And 3, the proportioning aging time is 24 hours, the volume of a precipitation layer is gradually reduced in the aging process, and finally fine grains are formed at the bottom of the beaker. The aging time of 6 proportions is 24-48h, and the sample in the beaker is gradually changed into anhydrous gel from liquid state in the aging process and finally into flocculent precipitate similar to uncongealed beancurd. The volume of the precipitation layer is thicker in the whole aging process, the thickness of the precipitation layer is slightly reduced after 24 hours, and the suspension property of the sample in the beaker is better. The 8 proportion is similar to the 6 proportion, but the final aging time of the 8 proportion is longer than that of the 6 proportion. After the product is completely aged, carrying out suction filtration; washing until the filtrate is free of chloride ions (the nitric acid acidified silver nitrate solution cannot be cloudy); the precipitate was dried at 80 ℃ to obtain a cerium-based precursor compound sample. The electron micrographs are shown in FIGS. 1a, 1b, and 1c, respectively. The results in the figure show that broom-like products are not obtained when the feed ratio is 3, while broom-like products can be obtained when the feed ratio is both 6 and 8, but broom-like products with 8 ratios have more scattered sticks and are not completely formed. So that as the feed ratio is increased,the formation of the broom-like product takes longer.

Example 2

1.4mol/L of CeCl is taken₃Adding 30mL of feed liquid into a beaker according to a set precipitation feed ratio [ HCO ]₃ ^-:Ce³⁺]Taking 250mL of ammonium bicarbonate solution as 6, adding into CeCl-containing solution at a certain flow rate₃In the beaker of the feed liquid, white precipitation can be observed in the solution immediately, and a large amount of bubbles are generated, after the precipitation reaction is fully completed, the beaker is sealed, and then the beaker is respectively placed in a water bath kettle with the temperature of 25 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ and 90 ℃ for aging. The sample aged at the normal temperature of 25 ℃ has a thicker precipitate layer, and the sample in the beaker gradually changes from liquid state to fine colloid state in the aging process and finally completely changes into bright and flashing coarse crystal precipitate. Aging at 40 deg.C for a long time until the solution reaches gel state, and aging for more than 10 days can not completely form broom-like cerium-based carbonate; aging at 50-70 deg.C, with the temperature rising, the time for the solution to reach gel state is shortened, and the time for forming broom-like cerium-based carbonate is also shortened. In the aging process at 80 ℃ and 90 ℃, the sample in the beaker is quickly changed from liquid to anhydrous gel, and then is converted into fine particle sediment at the bottom of the beaker, the volume of the sediment layer is greatly reduced, the appearance is changed from broom shape to small particle, and the small particle precursor is more completely formed at higher temperature. After the product is completely aged, carrying out suction filtration; washing until the filtrate is free of chloride ions (the nitric acid acidified silver nitrate solution cannot be cloudy); the precipitate was dried at 80 ℃ to obtain a cerium-based precursor compound sample. The electron micrographs are shown in FIG. 2, respectively. The results in the figure show that: aging at normal temperature and higher temperature to obtain broom-like product. Wherein the product obtained by aging at normal temperature is common flaky crystal; under high temperature conditions, however, a small particle product is obtained.

Example 3

1.4mol/L of CeCl is taken₃Adding 30mL of feed liquid into a beaker according to a set precipitation feed ratio [ HCO ]₃ ^-:Ce³⁺]Taking 250mL of ammonium bicarbonate solution as 6, adding into a water bath containing CeCl at a certain flow rate at 10 ℃, 45 ℃ and 70 ℃ respectively₃In the beaker of the feed liquid, the solution can be observedWhite precipitate appeared immediately with generation of a large amount of bubbles, and after the precipitation reaction was completed sufficiently, the beaker was sealed and placed in a water bath kettle at 60 ℃ for aging. After the product is completely aged, filtering and washing until the filtrate has no chloride ions (the silver nitrate solution acidified by nitric acid cannot become turbid); the precipitate was dried at 80 ℃ to obtain a cerium carbonate precursor sample. The electron micrographs are respectively shown in fig. 3a, b and c, and it can be seen that the precipitation temperature has no influence on the final morphology of the cerium-based precursor. The cerium carbonate precursor was calcined at different temperatures to obtain different sizes of grains as shown in table 1.

TABLE 1 specific surface area and grain size of cerium oxide calcined at different temperatures

Calcination temperature (. degree.C.)	Grain size (nm)	Specific surface area (m)²/g)
			400	6.4922	119.328
500	9.7027	71.547
			600	17.0398	32.538
700	33.9727	13.607
			800	50.1525	7.926
900	64.8459	5.947
			1000	83.3181	4.591

Example 4

Respectively taking 1.4mol/L of CeCl₃Adding 30mL of feed liquid into two beakers 1 and 2 according to a set precipitation feed ratio [ HCO ]₃ ^-:Ce³⁺]Taking 250mL of ammonium bicarbonate solution as 6, adding into CeCl-containing solution at a certain flow rate₃In the beaker of the feed liquid, magnetons are not discharged in the beaker 1, the reaction is carried out under the condition of no stirring, the reaction in the beaker 2 is carried out under the condition of stirring, white precipitates can be observed to be immediately generated in the solution, a large amount of bubbles are generated, after the precipitation reaction is fully completed, the beakers are sealed, and are respectively placed in a water bath kettle at 60 ℃ for aging. Aging was completed with suction filtration, and electron micrographs thereof are shown in FIGS. 4a and 4 b. It can be seen from the figure that no stirring is required during the reaction process, which is detrimental to the formation of a uniform broom-like morphology of the cerium-based precursor. And aging the sample in the beaker 2 for different times for sampling, wherein an electron microscope of the sample is shown in figure 5, and figure 5 shows that the broom-shaped cerium-based precursor is at least over 12 hours under the condition of medium temperature and high distribution.

Example 5

The resulting broom-like cerium-based precursor was subjected to a thermogravimetric test (at N)₂25-900 ℃ under protection, as can be seen from FIG. 7, the cerium-based carbonate precursor was completely converted to cerium oxide at about 400 ℃.

And (3) respectively placing the obtained precursor in muffle furnaces of 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃ and 1000 ℃ (a thermogravimetric data is supplemented, which shows that cerium oxide can be completely formed only at the temperature of more than 400 ℃, so that whether the data of the calcining temperature of more than 400 ℃ and 1100 ℃ needs to be put or not) and calcining for 3h to obtain the cerium-based oxide with different surface properties. The electron micrographs of the ceria calcined at different temperatures are shown in FIG. 8; XRD is shown in figure 9. The transmission patterns of the cerium oxide obtained by calcination at 400 ℃ and 900 ℃ are shown in FIG. 10. As can be seen from FIG. 8, the cerium oxide obtained by low-temperature (400-800 ℃) calcination still maintains broom-like morphology of the broom precursor, and when the cerium oxide is calcined at high temperature (>800 ℃), the broom-like single crystals of the cerium oxide are converted into small-particle beaded crystals. As can be seen from fig. 9, as the calcination temperature increases, the XRD peak becomes more sharp, the crystallinity of cerium oxide gradually becomes better, and the grain size gradually increases. As can be seen from the transmission graph of fig. 10, the broom-like cerium oxide after firing is assembled from small particles, and the size of the cerium oxide particles calcined at high temperature is larger than that of the cerium oxide particles calcined at low temperature, which is consistent with the data of fig. 8 and 9.

Example 6

Respectively taking 1.2mol/L of LaCl₃Adding 35mL of feed liquid into beaker 1, and taking 0.86mol/L YCl₃Adding 48.8mL of feed liquid into beaker 2 according to the set precipitation feed ratio [ HCO ]₃ ^-:RE³⁺]Weighing 250mL of ammonium bicarbonate solution, adding the ammonium bicarbonate solution into a beaker 1 and a beaker 2 at a certain flow rate, observing that white precipitation immediately occurs in the solution along with generation of a large amount of bubbles, sealing the beaker after the precipitation reaction is fully completed, and aging in a water bath kettle at 60 ℃ for 2 days. The volume of the precipitation layer in the beaker filled with the lanthanum solution is gradually reduced in the aging process, and the sample in the beaker is gradually changed into fine-grained particles from a liquid state. The beaker sample containing yttrium solution remained liquid at all times and the volume of the precipitate layer did not change much. After the product is completely aged, carrying out suction filtration; washing until the filtrate is free of chloride ions (the nitric acid acidified silver nitrate solution cannot be cloudy); the precipitate was dried at 80 ℃ to obtain a sample of the precursor, respectively. The electron micrographs are shown in FIGS. 11a and 11b, respectively. The results in the figure show that: lanthanum and yttrium alone cannot form broom-like precursors under the same conditions as broom-like, which may be related to the absence of valence variations in lanthanum and yttrium. And the single lanthanum forms a crushed hexagonal rhombohedral sheet shape, and the single yttrium forms a sphere-like shape.

Example 7

Respectively taking 1.4mol/L of CeCl₃27mL, 21mL, 15mL, and 9mL of the feed solution were placed in 1, 2, 3, and 4 beakers, and 1.2mol/L of LaCl was taken out₃3.5mL, 10.5mL, 17.5mL, 24.5mL of the feed liquid was added to the beakers of Nos. 1, 2, 3, and 4, and mixed well. According to the set precipitation charge ratio [ HCO ]₃ ^-:Re³⁺]Respectively measuring 250ml of ammonium bicarbonate solution, adding the ammonium bicarbonate solution into beakers numbered 1, 2, 3 and 4 at a certain flow rate, observing that white precipitates immediately appear in the solution and are accompanied by a large amount of bubbles, sealing the beakers after the precipitation reaction is fully completed, placing the beakers in a water bath kettle at 60 ℃ for aging, and performing suction filtration after aging of the beakers numbered 1, 2, 3 and 4 for 2 days, 3 days, 6 days and 10 days respectively; washing until the filtrate is free of chloride ions (the nitric acid acidified silver nitrate solution cannot be cloudy); drying the precipitate at 80 deg.C to obtain 10% La, 30% La and 50%La, 70% La cerium based precursor compound samples. The electron micrographs are respectively shown in fig. 12a, 12b, 12c and 12d, the precursor is calcined in a muffle furnace at 850 ℃ for 3h, and the XRD of the obtained sample is shown in fig. 13. It can be seen from fig. 12 that different proportions of La doping can still form broom-like precursor samples and the time required to form broom-like is longer with increasing La doping. As can be seen from fig. 13, XRD after calcination with La doped in different proportions remains the characteristic peak of ceria without other impurity peaks, and the relative intensity between the characteristic peaks is not significantly changed, indicating that there is no orientation growth. Compared with pure ceria, the crystallinity of the strong peak after doping with La will be somewhat lower, and the peak shifts to a low angle.

Example 8

Respectively taking 1.4mol/L of CeCl₃27mL, 21mL, 15mL, 9mL of the feed solution were placed in beakers numbered 1, 2, 3, 4, and then 1.029mol/L of PrCl was taken out₃Feed liquid 4mL, 12.2mL, 20.4mL, 28.5mL was added to the beakers numbered 1, 2, 3, 4 and mixed well. According to the set precipitation charge ratio [ HCO ]₃ ^-:Re³⁺]Respectively measuring 250mL of ammonium bicarbonate solution, adding the ammonium bicarbonate solution into beakers numbered 1, 2, 3 and 4 at a certain flow rate, observing that green precipitation immediately occurs in the solution and a large amount of bubbles are generated, sealing the beakers after the precipitation reaction is fully completed, and placing the beakers in a water bath kettle at 60 ℃ for aging for 4 days. After the product is completely aged, carrying out suction filtration; washing until the filtrate is free of chloride ions (the nitric acid acidified silver nitrate solution cannot be cloudy); and drying the precipitate at 80 ℃ to obtain a cerium-based precursor compound sample doped with 10% of Pr, 30% of Pr, 50% of Pr and 70% of Pr. The electron micrographs are respectively shown in fig. 14a, 14b, 14c and 14d, the precursor is calcined in a muffle furnace at 850 ℃ for 3h, and the XRD of the obtained sample is shown in fig. 15. As can be seen from fig. 14, different proportions of Pr doped to form broom-like precursor samples were still possible, but the rod diameter of broom-like praseodymium-based cerium salt precursors was smaller compared to the undoped ones, and the aging time was not extended as the amount of doped praseodymium was increased. As can be seen from FIG. 15, XRD still remains the characteristic peak of cerium oxide after calcination doped with different proportions of Pr, no other impurity peaks are present, and the relative intensities between the characteristic peaks are absentThere was a significant change indicating no epitaxial growth. Compared with pure ceria, the crystallinity of the strong peak becomes lower after Pr doping, and the peak shifts to a high angle.

Example 9

Respectively taking 1.4mol/L of CeCl₃27mL, 25.5mL, 24mL, 21mL of the feed liquid were placed in beakers numbered 1, 2, 3, 4, and then 0.86mol/L YCl was extracted₃Feed liquid 4.9mL, 7.3mL, 9.8mL, 14.65mL was added to the beakers numbered 1, 2, 3, 4 and mixed well. According to the set precipitation charge ratio [ HCO ]₃ ^-:Re³⁺]Respectively measuring 250mL of ammonium bicarbonate solution, adding the ammonium bicarbonate solution into beakers numbered 1, 2, 3 and 4 at a certain flow rate, observing that white precipitates immediately appear in the solution and are accompanied by a large amount of bubbles, sealing the beakers until the precipitation reaction is fully completed, placing the beakers in a water bath kettle at 60 ℃ for aging, and performing suction filtration after the product is aged for 2 days; washing until the filtrate is free of chloride ions (the nitric acid acidified silver nitrate solution cannot be cloudy); the precipitate was dried at 80 ℃ to obtain cerium-based precursor compound samples doped with 10% Y, 15% Y, 20% Y, and 30% Y. The electron micrographs are shown in FIGS. 16a, 16b, 16c, and 16 d. As can be seen from the figure: doping with 10% Y still allows to form broom-like yttrium-based cerium salt precursors, but at this time the broom-like single strip diameter is greatly reduced, resembling the feather shape. When the proportion of doped Y is increased, broom-like precursors can not be formed, but micro-nano particle precursors are formed.

Example 10

Respectively taking 1.4mol/L of CeCl₃27mL and 21mL of the feed liquid are put in beakers with numbers 1 and 2, and 0.9406mol/L of TbCl is taken respectively₃Feed liquids 4.47mL and 13.4mL were added to the beakers of Nos. 1 and 2 and mixed well. According to the set precipitation charge ratio [ HCO ]₃ ^-:Re³⁺]Respectively measuring 250mL of ammonium bicarbonate solution, adding the ammonium bicarbonate solution into beakers numbered 1 and 2 at a certain flow rate, observing that white precipitation appears in the solution immediately and is accompanied by a large amount of bubbles, sealing the beakers after the precipitation reaction is fully completed, placing the beakers in a water bath kettle at 60 ℃ for aging, and performing suction filtration after the product is completely aged; washing until the filtrate is free of chloride ions (incapable of acidifying nitric acid)The silver nitrate solution becomes cloudy); the precipitate was dried at 80 ℃ to obtain a cerium-based precursor compound sample doped with 10% Tb and 30% Tb. The electron micrographs are shown in FIGS. 17a and 17 b. As can be seen from the figure: the morphological characteristics of the terbium-doped material are similar to those of yttrium-doped material, and a broom-like terbium-based cerium salt precursor can be formed when the doping amount is 10%, but the diameter of a broom-like single strip is greatly reduced, and the broom-like single strip is similar to the shape of a feather. When the doping amount is continuously increased, broom-like precursors can not be formed, and micro-nano particle precursors are formed.

Example 11

1.4mol/LCeCl was taken₃Adding 30mL of feed liquid into a beaker according to a set precipitation feed ratio [ HCO ]₃ ^-:Ce³⁺]Taking 250mL of ammonium bicarbonate solution as 6, adding into CeCl-containing solution at a certain flow rate₃In the beaker of the feed liquid, white precipitation can be observed to occur immediately in the solution, a large amount of bubbles are generated, after the precipitation reaction is fully completed, the beaker is sealed, placed in a water bath kettle at 60 ℃ for aging, and after the product is completely aged, the product is filtered; washing until the filtrate is free of chloride ions (the nitric acid acidified silver nitrate solution cannot be cloudy); the precipitate was dried at 80 ℃ to obtain a cerium-based precursor compound sample. And calcining the precursor in muffle furnaces with the temperature of 900 ℃, 950 ℃, 1000 ℃, 1050 ℃ and 1100 ℃ respectively for 3 hours to obtain the cerium dioxide polishing powder with different surface properties. 20g of cerium dioxide polishing powder with different calcination temperatures is taken to prepare polishing solution with solid content of 1%, ZF7 glass is respectively polished by a Unipol-802 type precision grinding polisher (Shenyang crystal), the rotating speed is 200r/min, the pressure is 4.6kpa, the slurry flow rate is 2000mL/min, the polishing period is 1h, and the MRR average value is taken after 3 times of parallel measurement. The removal rate of the ceria polishing powder on ZF7 glass at different temperatures is shown in fig. 18; the pH change during polishing is shown in fig. 19; the potential change during polishing is shown in fig. 20. As can be seen from the figure: the removal rate of broom-shaped cerium dioxide calcined at different temperatures on ZF7 glass is different, and the best removal rate is achieved at 1000 ℃, and the removal rate reaches 272.23 nm/min. Along with the rise of the calcination temperature, the initial pH is gradually reduced, at 900-1000 ℃, the initial pH is alkalescent, and the pH shows the trend of first decreasing and then rising in the polishing process; at 1050 ℃ of 1000-The initial pH was weakly acidic and the pH gradually increased during polishing. The potential goes from positive to negative during polishing, which is related to the entry of the negatively charged corrosion layer of the glass into the slurry. Although the potential value is not large, the slurry has better suspension property in the actual polishing process because the broom-shaped slurry is easy to float in water.

Example 12

Example 13

Example 14

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which can be directly or indirectly applied to other related technical fields without departing from the spirit of the present invention, are included in the scope of the present invention.

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Cerium-based oxide material and preparation method of precursor thereof

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