CN112758968B - Alumina precursor and preparation method thereof, submicron alumina and preparation method thereof - Google Patents
Alumina precursor and preparation method thereof, submicron alumina and preparation method thereof Download PDFInfo
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 173
- 239000002243 precursor Substances 0.000 title claims abstract description 78
- 238000002360 preparation method Methods 0.000 title abstract description 48
- 238000006243 chemical reaction Methods 0.000 claims abstract description 66
- 238000000034 method Methods 0.000 claims abstract description 57
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 claims abstract description 40
- 238000001556 precipitation Methods 0.000 claims abstract description 38
- 239000012716 precipitator Substances 0.000 claims abstract description 31
- 239000011259 mixed solution Substances 0.000 claims abstract description 25
- 239000012266 salt solution Substances 0.000 claims abstract description 17
- 238000003756 stirring Methods 0.000 claims abstract description 14
- 239000002244 precipitate Substances 0.000 claims abstract description 9
- 239000006104 solid solution Substances 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 85
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 45
- 239000001099 ammonium carbonate Substances 0.000 claims description 45
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 25
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 25
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 20
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 17
- 239000004202 carbamide Substances 0.000 claims description 17
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 12
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 6
- 238000000926 separation method Methods 0.000 claims description 6
- 229910021529 ammonia Inorganic materials 0.000 claims description 3
- 235000013877 carbamide Nutrition 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 23
- 230000000694 effects Effects 0.000 abstract description 8
- 239000012535 impurity Substances 0.000 abstract description 6
- 230000007613 environmental effect Effects 0.000 abstract description 2
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- 230000000052 comparative effect Effects 0.000 description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 28
- 238000001914 filtration Methods 0.000 description 23
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 20
- 238000001816 cooling Methods 0.000 description 19
- 239000002360 explosive Substances 0.000 description 17
- 238000010438 heat treatment Methods 0.000 description 17
- 238000005406 washing Methods 0.000 description 17
- LCQXXBOSCBRNNT-UHFFFAOYSA-K ammonium aluminium sulfate Chemical compound [NH4+].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O LCQXXBOSCBRNNT-UHFFFAOYSA-K 0.000 description 16
- 238000001035 drying Methods 0.000 description 15
- 239000012452 mother liquor Substances 0.000 description 12
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 11
- 238000004090 dissolution Methods 0.000 description 10
- 239000000843 powder Substances 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 9
- 230000035484 reaction time Effects 0.000 description 9
- 239000003795 chemical substances by application Substances 0.000 description 8
- 239000012298 atmosphere Substances 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 7
- 230000001376 precipitating effect Effects 0.000 description 7
- 239000003463 adsorbent Substances 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 238000001354 calcination Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 238000001704 evaporation Methods 0.000 description 6
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 6
- 239000013078 crystal Substances 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000006911 nucleation Effects 0.000 description 5
- 238000010899 nucleation Methods 0.000 description 5
- HSEYYGFJBLWFGD-UHFFFAOYSA-N 4-methylsulfanyl-2-[(2-methylsulfanylpyridine-3-carbonyl)amino]butanoic acid Chemical compound CSCCC(C(O)=O)NC(=O)C1=CC=CN=C1SC HSEYYGFJBLWFGD-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 4
- 239000012065 filter cake Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- -1 aluminum alkoxide Chemical class 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 230000001186 cumulative effect Effects 0.000 description 3
- 239000012433 hydrogen halide Substances 0.000 description 3
- 229910000039 hydrogen halide Inorganic materials 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- RCTYPNKXASFOBE-UHFFFAOYSA-M chloromercury Chemical compound [Hg]Cl RCTYPNKXASFOBE-UHFFFAOYSA-M 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- ZSIAUFGUXNUGDI-UHFFFAOYSA-N hexan-1-ol Chemical compound CCCCCCO ZSIAUFGUXNUGDI-UHFFFAOYSA-N 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
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- 239000004094 surface-active agent Substances 0.000 description 2
- 238000012876 topography Methods 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
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- 150000001450 anions Chemical class 0.000 description 1
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- 239000003054 catalyst Substances 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
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- 229920001223 polyethylene glycol Polymers 0.000 description 1
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/34—Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
- C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention belongs to the technical field of alumina preparation, and particularly relates to an alumina precursorThe method comprises the steps of mixing and stirring an aluminum salt solution and a first precipitator, and reacting at the temperature of more than or equal to 10 ℃ until precipitates disappear to form a first reaction mixed solution; and adding a second precipitator into the first reaction mixed solution at a speed of more than or equal to 2g/min, and carrying out precipitation reaction at a temperature of more than or equal to 20 ℃ to obtain a mixed solution containing an alumina precursor solid solution. D of the alumina prepared by the invention 10 Is 80-150nm, D 50 Is 150-400nm, D 99 700-900nm, submicron level, uniform grain diameter, narrow distribution, good activity, purity more than 99.99 percent, less impurities, simple process and environmental protection.
Description
Technical Field
The invention belongs to the technical field of alumina preparation, and particularly relates to an alumina precursor and a preparation method thereof, submicron alumina and a preparation method thereof.
Background
The aluminum oxide is a high-hardness compound, has a melting point of 2054 ℃ and a boiling point of 2980 ℃, has excellent performances such as high hardness, high strength, good insulating property, high temperature and high pressure resistance, thermal shock resistance and the like, and is widely applied to high and new technical fields such as advanced structural ceramics, transparent ceramics, AlN substrates, composite ceramics, precision polishing, spraying and the like. The preparation of submicron alumina is also a research hotspot of researchers in the field, because the particle size and the particle size distribution of alumina can influence the activity and greatly influence the application.
Patent CN1033225C discloses a method for preparing size-controllable nano-submicron alumina powder, which comprises putting pure aluminum sheets or scraps into HgCl 2 Activating in water solution, hydrolyzing in distilled water, and high temperature heat treating to obtain size controllable nanometer or submicron level alumina powder. However, the preparation process requires that the purity of the aluminum is 99.5-99.999%, the price is expensive, and a highly toxic substance HgCl is utilized 2 Is used as an activating agent and is not good for environmental protection and health.
Patent CN1342609A disclosesFirstly, metal aluminum and alcohol are synthesized into aluminum alkoxide under the action of a catalyst, then the aluminum alkoxide is moved into a reduced pressure distillation device for refining and purification, the refined aluminum alkoxide is dissolved in a solvent, a proper amount of additive is added in the hydrolysis process, the hydrolysis product is filtered, dried at low temperature and roasted at high temperature to obtain alpha-A with the particle size of 50-300 nm and the purity of 99.99-99.999 percent 2 O 3 . However, the preparation method is complex, and most of the used alcohol, solvent and additive are flammable, explosive and toxic organic reagents.
Patent CN104528787B discloses a method for preparing fine-grained alumina powder, which uses industrial aluminum hydroxide or transition-phase alumina powder as raw material, adds seed crystal, dispersant, grain size control component and gas phase source into the raw material powder, and presses the raw material powder into a green body after mixing uniformly. Calcining the blank at high temperature in an atmosphere containing hydrogen halide and a particle size control component, crushing the calcined blank into powder, and calcining at low temperature in an atmosphere containing hydrogen halide with higher concentration after secondary forming to obtain alpha-Al with the particle size of less than 0.14 mu m 2 O 3 Is 100% of submicron or nanoscale alumina powder. However, the preparation method is too complicated, and the equipment requirement is harsh due to the use of high-concentration hydrogen halide for calcination.
Patent CN111392752A discloses submicron spherical alumina and a preparation method and application thereof, the method comprises the steps of preparing industrial aluminum hydroxide, a surfactant and water into first slurry, carrying out hydrothermal reaction for 2-16h at 60-150 ℃, and carrying out suction filtration to obtain a filter cake; acid washing the filter cake at 55-65 deg.c for 30-45min, and suction filtering to obtain aluminum hydroxide filter cake; adding water into the aluminum hydroxide filter cake to prepare a second slurry, drying, roasting and grinding to obtain spherical alpha-Al with the particle size of 0.1-1 mu m 2 O 3 . In the method, the surfactant is one or more of polyethylene glycol, butanol, glycerol and hexanol, all of which are organic solvents, so that the method is not environment-friendly and is complicated.
The methods for preparing submicron alumina all have some disadvantages, so that a preparation method of submicron alumina is needed, the particle size of alumina is submicron, and the process is simple and environment-friendly.
Disclosure of Invention
In order to solve the technical problems, the invention provides an alumina precursor and a preparation method thereof, submicron alumina and a preparation method thereof, and the prepared alumina is submicron, has high purity, simple and environment-friendly process and low cost.
In a first aspect, the present invention provides a method for preparing an alumina precursor, the method comprising,
mixing and stirring an aluminum salt solution and a first precipitator, and reacting at the temperature of more than or equal to 10 ℃ until precipitates disappear to form a first reaction mixed solution;
and adding a second precipitator into the first reaction mixed solution at a speed of more than or equal to 2g/min, and carrying out precipitation reaction at a temperature of more than or equal to 20 ℃ to obtain a mixed solution containing an alumina precursor solid solution.
Further, the temperature of the precipitation reaction is 20-70 ℃, and the time of the precipitation reaction is 10-600 s.
Further, the precipitation reaction is carried out to a pH of 4-6.
Further, the pH value of the first reaction mixed solution is 3 to 5.
Further, the molar concentration of the aluminum salt solution is more than or equal to 0.5 mol/L.
Further, the first precipitator is any one of the following: ammonium bicarbonate, ammonium carbonate and ammonia water, wherein the second precipitator is any one of the following: ammonium bicarbonate, ammonium carbonate, urea, and ammonia.
Further, the method comprises the step of carrying out solid-liquid separation on the mixed solution containing the alumina precursor solid solution to obtain an alumina precursor.
In a second aspect, the embodiments of the present invention provide an alumina precursor, where the alumina precursor is prepared by using the above-mentioned preparation method of a submicron alumina precursor.
In a third aspect, embodiments of the present invention provide a method for preparing submicron alumina, the method comprising,
drying the alumina precursor, and roasting at 550-1200 ℃ for 2-6 hours to obtain the submicron alumina.
In a fourth aspect, the embodiment of the present invention provides a submicron alumina, which is prepared by using the above preparation method of the submicron alumina.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
the invention provides an alumina precursor and a preparation method thereof, submicron alumina and a preparation method thereof, wherein the preparation process of the alumina precursor comprises two processes of preparation of a first reaction mixed solution, namely a metastable state solution and a rapid explosive precipitation reaction, firstly, an aluminum salt solution is adjusted to a metastable state, then a second precipitator is added at a certain speed under a limited temperature, the second precipitator and the first reaction mixed solution of the metastable state can generate explosive nucleation, the nucleation speed is enough to make crystal nuclei grow too soon, so that the superfine monodisperse alumina precursor with regular appearance is obtained, and the particle size of the prepared alumina is nanoscale and uniform in size after the alumina precursor is roasted due to the superfine monodisperse physical characteristics. D of the alumina prepared by the invention 10 Is 80-150nm, D 50 Is 150-400nm, D 99 Is 700-900nm, is submicron grade, has uniform grain diameter, narrow distribution and good activity, the purity is more than 99.99 percent, the impurity is less, and the process is simple and environment-friendly.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a process diagram of a method for preparing an alumina precursor according to an embodiment of the present invention;
FIG. 2 is a micro-topography of an alumina precursor according to an embodiment of the present invention;
FIG. 3 is an X-ray diffraction pattern of an alumina precursor provided in example 1 of the present invention;
FIG. 4 shows amorphous Al prepared in example 1 of the present invention 2 O 3 X-ray diffraction patterns of (a);
FIG. 5 shows γ -Al prepared in example 3 of the present invention 2 O 3 X-ray diffraction patterns of (a);
FIG. 6 is a view showing α -Al prepared in example 5 of the present invention 2 O 3 X-ray diffraction patterns of (a);
FIG. 7 shows the alpha-Al obtained after the calcination of the alumina precursor provided in example 5 of the present invention 2 O 3 The micro-topography of (a).
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
In order to solve the technical problems, the embodiment of the invention provides the following general ideas:
in a first aspect, an embodiment of the present invention provides a method for preparing an alumina precursor, which, with reference to fig. 1, includes,
s1, mixing and stirring the aluminum salt solution and the first precipitator, and reacting at the temperature of more than or equal to 10 ℃ until the precipitate disappears to form a first reaction mixed solution;
and S2, adding a second precipitator into the first reaction mixed solution at a speed of more than or equal to 2g/min, and carrying out precipitation reaction at a temperature of more than or equal to 20 ℃ to obtain a mixed solution containing an alumina precursor solid solution.
The preparation process of the alumina precursor comprises two processes of preparation of a first reaction mixed solution, namely a metastable state solution and a rapid explosive precipitation reaction, wherein firstly, an aluminum salt solution is adjusted to a metastable state, then a second precipitator is added at a certain speed under a limited temperature, the second precipitator and the first reaction mixed solution of the metastable state generate explosive nucleation, the nucleation speed is enough to ensure that crystal nuclei do not grow up soon, so that the superfine monodisperse alumina precursor with regular appearance is obtained, and the superfine monodisperse alumina precursor has the physical characteristics that after being roasted, the prepared alumina has the nanometer-scale grain diameter, uniform size and regular appearance.
The aluminum salt solution in the present invention can be obtained by: dissolving industrial aluminum salt such as any one of ammonium aluminum sulfate, aluminum sulfate and aluminum nitrate in water to form an industrial aluminum salt solution, heating and concentrating the industrial aluminum salt solution, cooling to 10-40 ℃, and filtering to obtain primary crystalline aluminum salt; heating and dissolving the primary crystallized aluminum salt, cooling to 10-40 ℃, and dissolving the aluminum salt obtained after filtering to obtain the aluminum salt lava. The aluminum salt prepared by the crystallization method has high purity of more than 99.99 percent, wherein the mass fraction of Fe is less than or equal to 10ppm, and the mass fraction of Ca is less than or equal to 10ppm, so that the high-purity aluminum salt is used as a raw material, and the purity of the prepared product submicron alumina is naturally higher; and the aluminum salt mother liquor generated in the two crystallization processes can be recycled.
The first and second precipitating agents may be obtained by the following method: the pre-precipitating agent and the precipitating agent of the invention can be obtained by respectively purifying the industrial pre-precipitating agent and the precipitating agent by utilizing the self-made high-purity alumina adsorbent, and the purity of the pre-precipitating agent and the precipitating agent is high, thereby ensuring the purity of the prepared submicron alumina. The first precipitant may be a solid or a solution, and is not particularly limited herein; the second precipitant may be either a solid or a solution, and is not particularly limited herein. 2g/min when the second precipitator is a solid, the second precipitator can be added into the first reaction mixed solution at a speed of more than or equal to 2 g/min; when the second precipitant is liquid, it may be added to the first reaction mixture solution at a rate of 200g/min or more.
The prepared mixed solution containing the alumina precursor is immediately filtered and washed to obtain amorphous superfine alumina hydrate, namely the alumina precursor. Wherein the washing process uses deionized water for repeated washing to remove SO 4 2- 、NO 3 - Plasma anions; and (4) evaporating and crystallizing mother liquor generated after the precipitation reaction of the metastable state solution and the second precipitator for subsequent utilization.
When the reaction temperature of the first precipitant and the aluminum salt is too low, the aluminum salt is precipitated in the aluminum salt solution, and the dissolved aluminum salt is too little, which is disadvantageous to the economy of the reaction.
As one implementation mode of the embodiment of the invention, the temperature of the precipitation reaction is 20-70 ℃, and the time of the precipitation reaction is 10-600 s.
The metastable state is easy to break due to the overhigh temperature of the precipitation reaction, and the precipitation is advanced; too low can seriously refine the size of the obtained precursor particles, so that the subsequent solid-liquid separation is difficult.
The precipitation reaction time is too long, so that the formed crystal nucleus grows too long, the size of an alumina precursor is also larger, the particle size of alumina is too large, and the activity is low; the precipitation reaction time is too short, the aim of fully mixing is difficult to achieve, the precipitation reaction is insufficient, and the yield is low.
As an implementation of the embodiment of the invention, the precipitation is carried out to a pH of 4 to 6. The excessive pH value at the end of the precipitation reaction means that the added second precipitator is excessive and the economy is poor; when the precipitation reaction is finished, the pH value is too low, so that the aluminum element cannot be precipitated as much as possible, and the yield is too low.
As an implementation mode of the embodiment of the invention, the reaction temperature of the aluminum salt solution and the first precipitator is 10-60 ℃. If the reaction temperature of the first precipitant and the aluminum salt is too high, the first precipitant is likely to precipitate in advance, and it is difficult to control the reaction rate.
As an embodiment of the present invention, the pH of the first reaction mixture solution is 3 to 5.
The pH value of the first reaction mixed solution is too high, so that a metastable state is broken, and a precipitation reaction is generated; if it is too small, the next step of rapid addition of the precipitant fails to achieve explosive precipitation and increases the amount of the second precipitant.
As an embodiment of the present invention, the molar concentration of the aluminum salt solution is not less than 0.5 mol/L.
The larger the molar concentration of the aluminum salt solution is, the more economical the amount of water used is, but the amount of aluminum salt dissolved at a certain temperature is limited by the saturation solubility of the aluminum salt.
As an implementation manner of the embodiment of the present invention, the first precipitator is any one of the following: ammonium bicarbonate, ammonium carbonate and ammonia water, wherein the second precipitator is any one of the following: ammonium bicarbonate, ammonium carbonate, urea, ammonia and water.
As an embodiment of the present invention, the method further includes, after solid-liquid separation of the mixture containing the solid solution of the alumina precursor, obtaining the alumina precursor.
In a second aspect, an embodiment of the present invention provides an aluminum oxide precursor, where the aluminum oxide precursor is prepared by using the above preparation method of an aluminum oxide precursor.
The microscopic morphology of the alumina precursor prepared by the invention is similar to spherical, and the alumina precursor has regular shape and uniform size by combining with figure 2, and the primary grain size is 50-500 nm. In a third aspect, embodiments of the present invention provide a method for preparing submicron alumina, the method comprising,
drying the alumina precursor, and roasting at 550-1200 ℃ for 2-6 hours to obtain the submicron alumina.
After the alumina precursor is roasted at high temperature, decomposition reaction occurs, so that submicron alumina is formed. The roasting temperature is too high, so that on one hand, the energy consumption is high, the cost is increased, and on the other hand, the obtained submicron alumina is sintered together; the roasting temperature is too low, and the precursor can not be completely converted into alumina; the primary grain growth of the obtained submicron alumina can be caused by the overlong roasting time, and large grains with the grain size of more than 1 mu m can appear; too short a precursor cannot be completely converted to alumina.
As an implementation manner of the embodiment of the invention, the drying temperature is 60-100 ℃, and the drying time is 5-10 h.
In a fourth aspect, the embodiment of the present invention provides a submicron alumina, which is prepared by using the above preparation method of the submicron alumina.
The submicron alumina obtained by the invention has stable product quality, purity of more than 99.99 percent, less impurities, grain size of less than 1 mu m and narrow grain size distribution, wherein D 50 Is 100-500nm, uniform in size and regular in shape.
An alumina precursor and a method for preparing the same, a submicron alumina and a method for preparing the same according to the present invention will be described in detail with reference to examples, comparative examples and experimental data.
Example 1
first, a method for preparing an alumina precursor
(1) And (3) crystallizing twice to purify aluminum salt: adding 1Kg of industrial grade aluminum sulfate into 1L of water, heating to boil, cooling to 10 ℃ after dissolution, and filtering to obtain primary crystalline aluminum sulfate; adding water into the primary crystalline aluminum sulfate, heating to boil, cooling to 10 ℃ after complete dissolution, and filtering to obtain the high-purity aluminum sulfate. The purity of the obtained high-purity aluminum sulfate is more than 99.99 percent, wherein the content of Fe is 3ppm, the content of Ca is 4ppm, and the high-purity aluminum sulfate is dissolved in water to form an aluminum sulfate solution with the concentration of 0.7 mol/L. The aluminum sulfate mother liquor generated in the two crystallization processes is recycled.
(2) Purifying ammonia water and urea solution: and respectively adding the self-made high-purity alumina adsorbent into ammonia water and urea solution, and filtering to respectively obtain high-purity ammonium bicarbonate solution and urea solution.
(3) Preparation of metastable state solution: and (2) adding the high-purity ammonia water prepared in the step (2) into 1L of high-purity aluminum sulfate solution prepared in the step (1) with the concentration of 0.7mol/L at the temperature of 20 ℃ under the stirring condition, wherein the adding speed is 15g/min, white flocculent precipitates disappear along with the stirring and redissolution, the adding amount of the ammonia water is controlled, and the pH value of the solution is adjusted to be 5 to form a metastable solution.
(4) Rapid explosive precipitation reaction: heating 1.5L and 0.2mol/L urea solution prepared in the step (2) to boiling, continuing for about 5min, cooling to 20 ℃, quickly adding the urea solution into the metastable state solution of the step (3) at 20 ℃ at the speed of 220g/min, carrying out explosive precipitation reaction, immediately filtering and washing to obtain amorphous superfine alumina hydrate, namely an alumina precursor, wherein the pH of the reaction end point is 6, and the reaction time is 100 s. Wherein the washing process uses deionized water for repeated washing to remove SO 4 2_ (ii) a And (3) evaporating and crystallizing mother liquor generated by the reaction of the metastable state solution and the precipitator for subsequent utilization.
Second, submicron alumina preparation
Drying and roasting: and (3) drying the alumina precursor prepared in the first part of step (4) for 5 hours in an air atmosphere at 80 ℃, then roasting for 5 hours in a high-temperature furnace at 800 ℃, naturally cooling and taking out to obtain the submicron-grade high-purity alumina (amorphous structure).
Example 2
first, a method for preparing an alumina precursor
(1) And (3) crystallizing twice to purify aluminum salt: adding 1Kg of industrial grade ammonium aluminum sulfate into 1L of water, heating to boil, cooling to 15 ℃ after dissolution, and filtering to obtain primary crystalline ammonium aluminum sulfate; adding water into the primary crystal ammonium aluminum sulfate, heating to boil, cooling to 15 ℃ after complete dissolution, and filtering to obtain the high-purity ammonium aluminum sulfate. The purity of the obtained high-purity ammonium aluminum sulfate is more than 99.99 percent, wherein the content of Fe is 3ppm, the content of Ca is 5ppm, and the high-purity ammonium aluminum sulfate is dissolved in water to form an ammonium aluminum sulfate solution with the concentration of 1.3 mol/L. The aluminum ammonium sulfate mother liquor generated in the two crystallization processes is recycled.
(2) Purifying the ammonium bicarbonate and urea solution: and respectively adding the self-made high-purity alumina adsorbent into the ammonium bicarbonate solution and the urea solution, and filtering to respectively obtain the high-purity ammonium bicarbonate solution and the high-purity urea solution.
(3) Preparation of metastable state solution: and (2) adding the high-purity ammonium bicarbonate solution prepared in the step (2) into 1L of high-purity aluminum ammonium sulfate solution prepared in the step (1) with the concentration of 1.3mol/L at the temperature of 50 ℃ under the stirring condition, wherein the adding speed is 25g/min, white flocculent precipitates disappear along with stirring and redissolving, the adding amount of the ammonium bicarbonate solution is controlled, and the solution is adjusted to pH 4 to form a metastable solution.
(4) Rapid explosive precipitation reaction: heating 2L and 0.17mol/L urea solution prepared in the step (2) to boiling, continuing for about 5min, cooling to 50 ℃, quickly adding the urea solution into the metastable state solution of the step (3) at 50 ℃ at the speed of 240g/min, carrying out explosive precipitation reaction, immediately filtering and washing to obtain amorphous superfine alumina hydrate, namely the alumina precursor, wherein the pH of the reaction end point is 5, and the reaction time is 90 s. Wherein the washing process uses deionized water for repeated washing to remove SO 4 2_ (ii) a And (3) evaporating and crystallizing mother liquor generated by the reaction of the metastable state solution and the precipitator for subsequent utilization.
Second, submicron alumina preparation
Drying and roasting: and (3) drying the alumina precursor prepared in the first part of step (4) for 5 hours in an air atmosphere at 80 ℃, then roasting for 4 hours in a high-temperature furnace at 900 ℃, naturally cooling and taking out to obtain the submicron-grade high-purity gamma alumina.
Example 3
Embodiment 3 provides an alumina precursor and a preparation method thereof, and submicron alumina and a preparation method thereof, and specifically includes the following steps:
first, a method for preparing an alumina precursor
(1) And (3) crystallizing twice to purify aluminum salt: adding 1.5Kg of industrial grade aluminum nitrate into 1L of water, heating to boil, cooling to 20 ℃ after dissolution, and filtering to obtain primary crystalline aluminum nitrate; adding water into the primary crystalline aluminum nitrate, heating to boil, completely dissolving, cooling to 20 ℃, and filtering to obtain the high-purity aluminum nitrate. The purity of the obtained high-purity aluminum nitrate is more than 99.99 percent, wherein the content of Fe is 6ppm, the content of Ca is 4ppm, and the high-purity aluminum nitrate is dissolved in water to form an aluminum nitrate solution with the concentration of 2 mol/L. And the aluminum nitrate mother liquor generated in the two crystallization processes is recycled.
(2) Purifying the ammonium carbonate solution and ammonia water: and respectively adding the self-made high-purity alumina adsorbent into the ammonium carbonate solution and the ammonia water, and filtering to obtain the high-purity ammonium carbonate solution and the high-purity ammonia water.
(3) Preparation of metastable state solution: and (2) adding the high-purity ammonium carbonate solution prepared in the step (2) into 1L of high-purity aluminum nitrate solution prepared in the step (1) with the concentration of 2mol/L under the condition of stirring at the temperature of 40 ℃, wherein the adding speed is 20g/min, white flocculent precipitates disappear along with the stirring and redissolution, the adding amount of the ammonium carbonate solution is controlled, and the pH value of the high-purity aluminum salt solution is adjusted to be 5, so that a metastable solution is formed.
(4) Rapid explosive precipitation reaction: heating 3L of high-purity ammonia water with the concentration of 2% prepared in the step (2) to 40 ℃, quickly adding the high-purity ammonia water into a metastable state solution with the temperature of 40 ℃ at the speed of 260g/min, carrying out explosive precipitation reaction, immediately filtering and washing to obtain amorphous superfine alumina hydrate, namely an alumina precursor, wherein the pH value at the end of the reaction is 6, and the reaction time is 420 s. Wherein the washing process uses deionized water for repeated washing to remove NO 3 _ (ii) a And (3) evaporating and crystallizing mother liquor generated by the reaction of the metastable state solution and the precipitator for subsequent utilization.
Second, submicron alumina preparation
Drying and roasting: and (3) drying the first part of the alumina precursor prepared in the step (4) for 8 hours in an air atmosphere at 60 ℃, then roasting for 2 hours in a high-temperature furnace at 1000 ℃, naturally cooling and taking out to obtain the submicron-grade high-purity gamma-alumina.
The submicron alpha alumina prepared in example 2 was tested for purity > 99.99% and the results of the plasma emission spectrometer (ICP) data are shown in table 2:
example 4
first, a method for preparing an alumina precursor
(1) And (3) crystallizing twice to purify aluminum salt: adding 1Kg of industrial grade ammonium aluminum sulfate into 1L of water, heating to boil, cooling to 25 ℃ after dissolution, and filtering to obtain primary crystalline ammonium aluminum sulfate; adding water into the primary crystalline ammonium aluminum sulfate, heating to boil, cooling to 25 ℃ after complete dissolution, and filtering to obtain the high-purity ammonium aluminum sulfate. The purity of the obtained high-purity ammonium aluminum sulfate is more than 99.99 percent, wherein the content of Fe is 3ppm, the content of Ca is 5ppm, and the high-purity ammonium aluminum sulfate is dissolved in water to form an ammonium aluminum sulfate solution with the concentration of 1.3 mol/L. The aluminum ammonium sulfate mother liquor generated in the two crystallization processes is recycled.
(2) Purifying ammonium bicarbonate and ammonium carbonate solution: and adding the self-made high-purity alumina adsorbent into the ammonium bicarbonate solution and the ammonium carbonate solution, and filtering to obtain the high-purity ammonium bicarbonate solution and the high-purity ammonium carbonate solution.
(3) Preparation of metastable state solution: and (2) adding the high-purity ammonium bicarbonate solution prepared in the step (2) into 1L of high-purity aluminum ammonium sulfate solution prepared in the step (1) with the concentration of 1.3mol/L at the temperature of 70 ℃ under the stirring condition, wherein the adding speed is 40g/min, white flocculent precipitates disappear along with stirring and redissolving, the adding amount of the ammonium bicarbonate solution is controlled, and the solution is adjusted to pH 4 to form a metastable solution.
(4) Rapid explosive precipitation reaction: heating 1L and 0.2mol/L ammonium carbonate solution prepared in the step (2) to 70 ℃, rapidly adding the solution into the metastable state solution of the step (3) at 70 ℃ at the speed of 180g/min, carrying out explosive precipitation reaction, immediately filtering and washing to obtain amorphous superfine alumina hydrate, namely an alumina precursor, wherein the pH at the end point of the reaction is 6, and the reaction time is 200 s. Wherein the washing process uses deionized water for repeated washing to remove SO 4 2_ (ii) a And (3) evaporating and crystallizing mother liquor generated by the reaction of the metastable state solution and the precipitator for subsequent utilization.
Second, submicron alumina preparation
Drying and roasting: and (3) drying the first part of the alumina precursor prepared in the step (4) in an air atmosphere at 60 ℃ for 8 hours, then roasting in a high-temperature furnace at 1100 ℃ for 6 hours, naturally cooling, and taking out to obtain the submicron-grade high-purity alpha alumina.
Example 5
Embodiment 5 provides an alumina precursor and a preparation method thereof, and a submicron alumina and a preparation method thereof, and the method comprises the following specific steps:
first, a method for preparing an alumina precursor
(1) And (3) crystallizing twice to purify aluminum salt: adding 1Kg of industrial grade aluminum sulfate into 1L of water, heating to boil, cooling to 15 ℃ after dissolution, and filtering to obtain primary crystalline aluminum sulfate; adding water into the primary crystalline aluminum sulfate, heating to boil, cooling to 15 ℃ after complete dissolution, and filtering to obtain the high-purity aluminum sulfate. The purity of the obtained high-purity aluminum sulfate is more than 99.99 percent, wherein the content of Fe is 2ppm, the content of Ca is 3ppm, and the high-purity aluminum sulfate is dissolved in water to form an aluminum sulfate solution with the concentration of 0.7 mol/L. The aluminum sulfate mother liquor generated in the two crystallization processes is recycled.
(2) Purifying ammonium carbonate and ammonium bicarbonate solution: and adding the self-made high-purity alumina adsorbent into the ammonium carbonate solution and the ammonium bicarbonate solution, and filtering to obtain the high-purity ammonium carbonate solution and the high-purity ammonium bicarbonate solution.
(3) And (2) adding the high-purity ammonium carbonate solution prepared in the step (2) into 1L of high-purity aluminum sulfate solution prepared in the step (1) with the concentration of 0.7mol/L under the condition of stirring at the temperature of 50 ℃, wherein the adding speed is 30g/min, white flocculent precipitates disappear along with the stirring and redissolution, the adding amount of the ammonium carbonate solution is controlled, and the pH value of the high-purity aluminum salt solution is adjusted to 4 to form a metastable state solution.
(4) Rapid explosive precipitation reaction: heating 1.5L and 0.2mol/L ammonium bicarbonate solution prepared in the step (2) to 60 ℃, rapidly adding the ammonium bicarbonate solution into the metastable state solution of the step (3) at the temperature of 60 ℃ at the speed of 250g/min, carrying out explosive precipitation reaction, immediately filtering and washing to obtain amorphous superfine alumina hydrate, namely the alumina precursor, wherein the pH of the reaction end point is 6, and the reaction time is 300 s. Wherein, washingThe process uses deionized water for repeated washing to remove SO 4 2_ (ii) a And (3) evaporating and crystallizing mother liquor generated by the reaction of the metastable state solution and the precipitator for subsequent utilization.
Second, submicron alumina preparation
Drying and roasting: and (3) drying the first part of the alumina precursor prepared in the step (4) in an air atmosphere at 60 ℃ for 8 hours, then roasting in a high-temperature furnace at 1200 ℃ for 6 hours, naturally cooling, and taking out to obtain the submicron-grade high-purity alpha alumina.
Example 6
Example 6 referring to example 5, example 6 differs from example 5 in that: the ammonium bicarbonate solution in step (2) was replaced with ammonium bicarbonate solid powder, and ammonium bicarbonate powder was added to the metastable solution at a rate of 3g/min in step (4), the rest being the same as in example 5.
Comparative example 1
Comparative example 1 reference example 1, comparative example 1 differs from example 1 in that: in the step (3), the temperature is 3 ℃, the temperature of the urea in the step (4) is reduced to 10 ℃, and the urea is added into the metastable state solution in the step (3) at the rate of 1g/min, and the rest is the same as the example 1.
Comparative example 2
Comparative example 2 reference example 1, comparative example 2 differs from example 1 in that: in step (3), the temperature was 3 ℃ and the rest was the same as in example 1.
Comparative example 3
Comparative example 3 reference example 1, comparative example 3 differs from example 1 in that: the urea in step (4) was cooled to a temperature of 10 ℃ and the rest was the same as in example 1.
Comparative example 4
Comparative example 4 reference example 1, comparative example 4 differs from example 1 in that: urea was added to the metastable solution of step (3) at a rate of 1g/min in step (4), the remainder being the same as in example 1.
Comparative example 5
Comparative example 5 reference example 1, comparative example 5 differs from example 1 in that: the second part of submicron alumina is prepared by the method, wherein the roasting temperature is 1300 ℃.
Comparative example 6
Comparative example 6 reference example 1, comparative example 6 differs from example 1 in that: the roasting temperature in the preparation method of the second part of submicron alumina is 450 ℃.
The aluminum oxide precursors prepared in examples 1 to 6 and comparative examples 1 to 6 were observed under a scanning electron microscope, the micro-morphology of the aluminum oxide precursor of the example of the present invention is shown in fig. 2, and the particle size detection was performed, and the results are shown in table 1. The alumina prepared in the examples 1 to 6 and the alumina prepared in the comparative examples 1 to 6 are observed under a scanning electron microscope, the alumina morphology of the example 5 of the invention is shown in figure 3, and the particle size detection is carried out, specifically shown in table 2, and the impurity content of the alumina prepared in the examples 1 to 5 and the alumina prepared in the comparative examples 1 to 6 is shown in table 3.
TABLE 1
TABLE 2
| Numbering | D 10 /nm | D 50 /nm | D 99 /nm | Purity/%) |
| Example 1 | 80 | 150 | 600 | >99.99％ |
| Example 2 | 100 | 200 | 700 | >99.99％ |
| Example 3 | 130 | 400 | 900 | >99.99％ |
| Example 4 | 120 | 380 | 900 | >99.99％ |
| Example 5 | 130 | 400 | 950 | >99.99％ |
| Example 6 | 150 | 390 | 950 | >99.99％ |
| Comparative example 1 | 200 | 500 | 1000 | >99.99％ |
| Comparative example 2 | 80 | 180 | 650 | >99.99％ |
| Comparative example 3 | 80 | 130 | 550 | >99.99％ |
| Comparative example 4 | 220 | 530 | 1100 | >99.99％ |
| Comparative example 5 | 300 | 600 | 1200 | >99.99％ |
| Comparative example 6 | 60 | 120 | 210 | >99.99％ |
TABLE 3
In tables 1 to 3, D 50 The particle size is expressed as the percentage of the cumulative particle size distribution of the alumina particles reaching 50%. Its physical meaning is a particle size greater than D 50 Is 50% less than D 50 Also 50% of particles of (D) 50 Also known as median or median particle diameter. D 99 The particle size is expressed as the percentage of the cumulative particle size distribution of the alumina particles reaching 99%. I.e., less than the particle diameter (D) 99 ) The volume content of the particles of (1) is 99% of the total particles. D 10 The particle size is expressed as the percentage of the cumulative particle size distribution of the alumina particles reaches 10%. I.e., less than the particle diameter (D) 10 ) The volume content of the particles of (a) is 10% of the total particles. D 50 And D 99 The smaller the value of (A), the smaller the particle size of alumina, the higher the activity. D 10 、D 50 And D 99 The closer the values of the three are, the more uniform the particle size of the alumina is, the smaller the fluctuation is, and the higher the activity is.
As is clear from the data in tables 1 to 3, D of the alumina prepared in examples 1 to 6 10 Is 80-150nm, D 50 Is 150-400nm, D 99 Is 600-950nm, is submicron grade, has uniform grain diameter, has purity more than 99.99 percent and has less impurities.
Comparative example 1, wherein the preliminary precipitation temperature was too low, the reaction time was too long, and D was obtained as alumina 10 Is 200nm, D 50 Is 500nm, D 99 1000nm, the particle size is larger than that of the examples 1-6 of the invention, and the proposal causes the problems of poor economy and difficult solid-liquid separation.
In comparative example 2, the pre-precipitation temperature was too low to allow complete dissolution of aluminum salt, which is less economical than examples 1-6 of the present invention; d of the prepared alumina 10 Is 80nm, D 50 The particle size is 180nm, and the particle size is,D 99 is 650 nm.
Comparative example 3, D of alumina precursor prepared at excessively low reaction temperature 10 Is 50nm, D 50 Is 80nm, D 99 150nm, and the obtained alumina precursor has a nanometer-scale particle size, but is not beneficial to subsequent solid-liquid separation and other operations.
Comparative example 4, D of alumina prepared under too long a reaction time 10 Is 220nm, D 50 Is 530nm, D 99 1100nm, and a particle size larger than that of inventive examples 1-6, due to the time for nucleation to grow up.
Comparative example 5, D of alumina prepared under the condition of excessively high calcination temperature 10 Is 300nm, D 50 Is 600nm, D 99 1200nm, larger than the particles of examples 1 to 6 of the present invention, due to the agglomeration caused by the adhesion between grains caused by the excessively high firing temperature.
Comparative example 6, D of alumina prepared at too low a calcination temperature 10 Is 60nm, D 50 Is 120nm, D 99 The particle size is 210nm, the morphology and the granularity characteristics of the precursor can be still maintained, and the precursor is of an amorphous structure.
As can be seen from FIG. 2, the precursors of examples 1 to 6 all have a spherical shape, a regular morphology, a uniform size and a primary grain size of 50 to 500 nm.
As can be seen from FIGS. 3 to 7, the alumina precursors obtained in examples 1 to 6 of the present invention have amorphous structures and uniform purities>99.995%; when the roasting temperature is less than or equal to 800 ℃, the prepared alumina is in an amorphous structure; when the roasting temperature is more than 800 ℃, the prepared alumina starts to change from an amorphous structure to gamma-Al 2 O 3 Conversion, when the roasting temperature is 1000 deg.C, the obtained aluminium oxide is completely gamma-Al 2 O 3 (ii) a When the roasting temperature is more than 1000 ℃, the prepared alumina starts to convert to gamma-Al 2 O 3 To alpha-Al 2 O 3 When the roasting temperature is 1200 ℃, the prepared alumina is alpha-Al 2 O 3 . The alumina precursors obtained in comparative examples 1 to 6 are all amorphous structures and have the same purity>99.995 percent, the roasting temperature is less than or equal to 800 ℃, and the prepared alumina is also amorphousStructure; when the roasting temperature is 800 ℃, the prepared alumina is converted into gamma-Al from an amorphous structure 2 O 3 When the roasting temperature is 1000 ℃, the prepared alumina is completely converted into gamma-Al 2 O 3 (ii) a When the roasting temperature is more than 1000 ℃, the prepared alumina starts to convert to gamma-Al 2 O 3 To alpha-Al 2 O 3 When the roasting temperature is 1200 ℃, the prepared alumina is all alpha-Al 2 O 3 。
The alumina precursor and the preparation method thereof, the submicron alumina and the preparation method thereof provided by the invention at least have the following advantages:
(1) the process flow is simple and the cost is low. The raw material aluminum salt is crystallized and purified by any one of industrial-grade ammonium aluminum sulfate, aluminum sulfate and aluminum nitrate, the process is simple and easy to implement, the purification of the first precipitator and the second precipitator is a simple physical adsorption process, and the rapid explosive precipitation reaction between the second precipitator and the first reaction mixed solution is a simple chemical precipitation process. The used raw materials of aluminum salt, pre-precipitant and precipitant are all industrial grade raw materials, the price is low, and the process is simple and environment-friendly.
(2) The purity index is stable. The raw materials of aluminum salt, pre-precipitant and precipitant used in the process of preparing the alumina precursor and submicron alumina are all purified by adopting industrial grade raw materials, and the prepared submicron alumina has the purity of more than 99.99 percent, high and stable purity and less impurities.
(3) Prepared submicron alumina D 10 Is 80-150nm, D 50 Is 150-400nm, D 99 Is 700-900nm, narrow particle size distribution, uniform size and regular appearance.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (2)
1. A method for preparing an alumina precursor, characterized in that the method comprises,
mixing and stirring an aluminum salt solution and a first precipitator, reacting at a temperature of more than or equal to 10 ℃ until a precipitate disappears to form a first reaction mixed solution, wherein the first reaction mixed solution is a metastable state solution;
adding a second precipitator into the first reaction mixed solution at a speed of more than or equal to 2g/min, and carrying out precipitation reaction at a temperature of more than or equal to 20 ℃ to obtain a mixed solution containing an alumina precursor solid solution;
carrying out solid-liquid separation on the mixed solution containing the alumina precursor solid solution to obtain an alumina precursor;
the temperature of the precipitation reaction is 20-70 ℃, and the time of the precipitation reaction is 10-600 s;
the precipitation reaction is carried out until the pH value is 4-6;
the pH value of the first reaction mixed solution is 3-5;
the molar concentration of the aluminum salt solution is more than or equal to 0.5 mol/L;
the first precipitator is any one of the following: ammonium bicarbonate, ammonium carbonate and ammonia water, wherein the second precipitator is any one of the following: ammonium bicarbonate, ammonium carbonate, urea, and ammonia.
2. A method for preparing submicron alumina, which is characterized in that the method comprises the following steps,
the alumina precursor of claim 1 is dried and then calcined at 550-1200 ℃ for 2-6 hours to obtain submicron alumina.
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