CN117003272A - Modified alumina with high thermal stability and preparation method thereof - Google Patents
Modified alumina with high thermal stability 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 87
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 239000011148 porous material Substances 0.000 claims abstract description 65
- 239000000243 solution Substances 0.000 claims abstract description 57
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical class O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims abstract description 31
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 30
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 30
- 239000011734 sodium Substances 0.000 claims abstract description 30
- 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 claims abstract description 29
- 239000002002 slurry Substances 0.000 claims abstract description 20
- 239000011259 mixed solution Substances 0.000 claims abstract description 19
- 235000019353 potassium silicate Nutrition 0.000 claims abstract description 15
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000001914 filtration Methods 0.000 claims abstract description 12
- 238000005406 washing Methods 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 11
- 150000001875 compounds Chemical class 0.000 claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 8
- 239000010452 phosphate Substances 0.000 claims abstract description 8
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 27
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 24
- 229910052782 aluminium Inorganic materials 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 claims description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 12
- 229910052710 silicon Inorganic materials 0.000 claims description 12
- 239000010703 silicon Substances 0.000 claims description 12
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 11
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims description 11
- 239000011574 phosphorus Substances 0.000 claims description 11
- 238000001354 calcination Methods 0.000 claims description 9
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 239000003054 catalyst Substances 0.000 claims description 6
- 238000002425 crystallisation Methods 0.000 claims description 5
- 230000008025 crystallization Effects 0.000 claims description 5
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 claims description 2
- 229910000402 monopotassium phosphate Inorganic materials 0.000 claims description 2
- 235000019796 monopotassium phosphate Nutrition 0.000 claims description 2
- 229910000403 monosodium phosphate Inorganic materials 0.000 claims description 2
- 235000019799 monosodium phosphate Nutrition 0.000 claims description 2
- 125000002467 phosphate group Chemical group [H]OP(=O)(O[H])O[*] 0.000 claims description 2
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 claims description 2
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 2
- 239000008367 deionised water Substances 0.000 description 20
- 229910021641 deionized water Inorganic materials 0.000 description 20
- 238000000034 method Methods 0.000 description 18
- 238000002156 mixing Methods 0.000 description 13
- 239000012065 filter cake Substances 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 8
- 238000010304 firing Methods 0.000 description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 7
- DNEHKUCSURWDGO-UHFFFAOYSA-N aluminum sodium Chemical compound [Na].[Al] DNEHKUCSURWDGO-UHFFFAOYSA-N 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000000706 filtrate Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910001593 boehmite Inorganic materials 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 description 2
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Chemical compound [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- SMZOGRDCAXLAAR-UHFFFAOYSA-N aluminium isopropoxide Chemical compound [Al+3].CC(C)[O-].CC(C)[O-].CC(C)[O-] SMZOGRDCAXLAAR-UHFFFAOYSA-N 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 229910000397 disodium phosphate Inorganic materials 0.000 description 1
- 235000019800 disodium phosphate Nutrition 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000012782 phase change material Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 238000002210 supercritical carbon dioxide drying Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- WOZZOSDBXABUFO-UHFFFAOYSA-N tri(butan-2-yloxy)alumane Chemical compound [Al+3].CCC(C)[O-].CCC(C)[O-].CCC(C)[O-] WOZZOSDBXABUFO-UHFFFAOYSA-N 0.000 description 1
- ZSDSQXJSNMTJDA-UHFFFAOYSA-N trifluralin Chemical compound CCCN(CCC)C1=C([N+]([O-])=O)C=C(C(F)(F)F)C=C1[N+]([O-])=O ZSDSQXJSNMTJDA-UHFFFAOYSA-N 0.000 description 1
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
- C01F7/44—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
- 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
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
-
- 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
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/14—Aluminium oxide or hydroxide from alkali metal aluminates
-
- 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
- C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
- C01F7/32—Thermal decomposition of sulfates including complex sulfates, e.g. alums
-
- 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
- C01P2006/12—Surface area
-
- 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
- C01P2006/14—Pore volume
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention relates to the technical field of modified alumina, and discloses modified alumina with high thermal stability and a preparation method thereof. The preparation method of the modified alumina comprises the following steps: (1) Dropwise adding water glass and a phosphate-containing compound into a mixed solution of an aluminum sulfate solution and a sodium metaaluminate solution to obtain a mixed solution; (2) crystallizing the mixed solution to obtain slurry; filtering, washing and drying the slurry to obtain modified boehmite; (3) Roasting the modified boehmite at 600-1400 ℃ to obtain the modified alumina. The preparation method is green and clean, solves the problems of poor thermal stability, small specific surface area and small pore volume of the alumina obtained by production, and reduces the production cost.
Description
Technical Field
The invention relates to the technical field of modified alumina, in particular to modified alumina with high thermal stability and a preparation method thereof.
Background
The alumina has the characteristics of large specific surface area, good pore channel structure, higher thermal stability and the like, and can be widely applied to a plurality of fields such as adsorbents, catalysts, carriers, fillers, drying agents and the like.
Activated alumina is typically produced by firing boehmite. Wherein, gamma-Al 2 O 3 Is very important alumina, and the annual output can reach hundreds of thousands tons. However, in the case of high temperature calcination, gamma-Al 2 O 3 Will be converted into a more stable form, with a specific surface area of typically less than 20m 2 alpha-Al/g 2 O 3 . How to improve the thermal stability of activated alumina is one of the hot spots in alumina research.
At present, the chemical industry has more high-temperature reactions, such as methane and carbon dioxide dry reforming, and the main reaction is CH 4 With CO 2 Reaction to produce H 2 And CO, the reaction Δg= 61770 to 67.32T, Δg is negative above 645 ℃, and the reaction needs to be carried out at a high temperature of about 1000 ℃, and the catalyst carrier is usually alumina, and the active metal comprises nickel or ruthenium. Good thermal stability must be provided for alumina used at high temperatures. Whereas alumina typically sinters during firing, resulting in a reduction in alumina pore structure. There have been extensive studies heretofore in improving the thermal stability of alumina.
Mardkhe et al prepared modified alumina by reacting tetraethyl orthosilicate containing 5wt% silica with aluminum isopropoxide, which had a specific surface area of 160.0m after calcination at 1100 ℃ 2 Per gram, pore volume of 0.99cm 3 /g, but the cost of raw materials is too high and environmental problems of the preparation process limit its industrial application.
Liu Yong et al prepared strontium-modified alumina by sol-gel method, using aluminum sec-butoxide and strontium nitrate as raw materials, and roasting at 1150 deg.C to obtain sample with specific surface area of 83.5m when strontium oxide/aluminum oxide is 0.05 (molar ratio) 2 /g, about unmodified alumina (9.8 m 2 Per g) and is not converted into alpha-Al 2 O 3 Shows that the introduction of strontium inhibits Al 2 O 3 The thermal stability of the phase change material is remarkably improved.
Ray et al have found that when carboxylic acids are used as anionic structure directing agents with styrene-butadiene-acrylonitrile copolymers (ASB) in organic solvents, they are prepared at a firing temperature of 800℃Sample specific surface area of 258.0m 2 Per gram, pore volume of 0.63cm 3 /g, and still be gamma-Al 2 O 3 。
As can be seen, there is a great need to develop a method for preparing modified alumina with high thermal stability, which is clean and low in production cost.
Disclosure of Invention
The invention aims to overcome the defect that the specific surface area of active alumina is greatly reduced after high-temperature roasting in the prior art, and provides modified alumina with high thermal stability and a preparation method thereof.
In order to achieve the above object, a first aspect of the present invention provides a method for producing a modified alumina having high thermal stability, wherein the method comprises:
(1) Dropwise adding water glass and a phosphate-containing compound into a mixed solution of an aluminum sulfate solution and a sodium metaaluminate solution to obtain a mixed solution;
(2) Crystallizing the mixed solution to obtain slurry; filtering, washing and drying the slurry to obtain modified boehmite;
(3) Roasting the modified boehmite at 600-1400 ℃ to obtain the modified alumina.
In a second aspect, the present invention provides a modified alumina having high thermal stability, prepared by the aforementioned preparation method.
Through the technical scheme, the macroporous large-specific surface area modified alumina with high thermal stability can be obtained, and the preparation method is green and clean, and reduces the production cost.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
As described above, the present invention provides a method for preparing modified alumina having high thermal stability, wherein the method comprises:
(1) Dropwise adding water glass and a phosphate-containing compound into a mixed solution of an aluminum sulfate solution and a sodium metaaluminate solution to obtain a mixed solution;
(2) Crystallizing the mixed solution to obtain slurry; filtering, washing and drying the slurry to obtain modified boehmite;
(3) Roasting the modified boehmite at 600-1400 ℃ to obtain the modified alumina.
The inventors of the present invention found that: after roasting at a temperature above 1000 ℃, the specific surface area of the activated alumina can be greatly reduced. In addition, the existing method for preparing the alumina with large pores and large specific surface area generally requires supercritical carbon dioxide drying or organic matter addition, and has the disadvantages of complex operation, high cost and environmental friendliness. Under the condition of no organic matters, the preparation of alumina with excellent thermal stability by using easily available inorganic chemical raw materials through a simple process is still a problem to be solved. Because phosphate radical has a limiting effect on the growth of boehmite, the thickness of a sheet and a close packing mode of a sample can be reduced by the limiting effect, the specific surface area and the pore structure of the prepared sample are increased, and the introduction of silicon can improve the thermal stability of the sample and prevent the sample from being formed by gamma-Al 2 O 3 To alpha-Al 2 O 3 The crystal form of the catalyst is changed, a good pore structure is still maintained after high-temperature roasting, and the alpha-Al is improved 2 O 3 Is a phase transition temperature of (c). The inventors of the present invention have obtained a modified alumina having a large pore and a large specific surface area and having high thermal stability by modifying silicon and phosphorus.
According to the present invention, preferably, the conditions of the firing include: the temperature is 600-1200 ℃ and the time is 1-20h. In the invention, the modified boehmite is baked under different temperature conditions, so that the modified alumina with different specific surface areas and pore volumes can be obtained.
According to the invention, the pH of the suspension is 8-11, preferably 8.5-9.5; in the present invention, the purpose of controlling the pH value is to control the specific surface area and pore volume of the modified boehmite.
According to the invention, in the sodium metaaluminate solution, the content of aluminum is 5-10wt% based on aluminum oxide, and the molar ratio of sodium to aluminum is 3-5.5; preferably, the sodium metaaluminate solution has an aluminum content of 6-7wt% in terms of aluminum oxide, and a molar ratio of sodium to aluminum of 4-4.8.
In the invention, the preparation method of the sodium metaaluminate solution comprises the following steps: the sodium hydroxide, the aluminum hydroxide and the water react to obtain the catalyst; wherein the reaction conditions include: the temperature is 120-160 ℃ and the time is 2-5h.
According to the present invention, the phosphate group-containing compound includes one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate and potassium dihydrogen phosphate; disodium hydrogen phosphate is preferred.
According to the invention, the concentration of the aluminum sulfate solution is 0.1 to 0.7mol/kg, preferably 0.2 to 0.6mol/kg.
According to the invention, the specific surface area of the modified boehmite is 500-800m 2 Per gram, pore volume of 3-4cm 3 /g; preferably, the specific surface area of the modified boehmite is 550-750m 2 Per gram, pore volume of 3.1-3.9cm 3 /g。
According to the invention, the molar ratio of the silicon content in the water glass calculated as silicon element, the phosphorus content in the phosphate-containing compound calculated as phosphorus element and the total aluminum content calculated as aluminum element in the sodium metaaluminate and the aluminum sulfate is (0.01-0.21): (0.02-0.71): 1; preferably, the molar ratio of silicon to phosphorus to aluminum is (0.02-0.15): (0.03-0.41): 1, wherein "silicon" is the content of silicon in terms of silicon element in the water glass, "phosphorus" is the content of phosphorus in terms of phosphorus element in the phosphate-containing compound, and "aluminum" is the content of total aluminum in terms of aluminum element in the sodium metaaluminate and the aluminum sulfate.
According to the present invention, the crystallization conditions include: the temperature is 50-230 ℃ and the time is 1-100h; preferably, the crystallization conditions include: the temperature is 90-210 ℃ and the time is 2-20h.
According to the present invention, after the crystallization reaction is completed, the autoclave is cooled to room temperature, and then the obtained white precipitate is filtered, washed with deionized water, and dried. Wherein, the filtration adopts buchner funnel filtration.
According to the invention, deionized water is used for washing, and the washing times are 2-4 times.
According to the invention, the drying conditions include: the temperature is 80-200deg.C, preferably 140-180deg.C.
In a second aspect, the present invention provides a modified alumina having high thermal stability prepared by the aforementioned preparation method.
According to the invention, the specific surface area of the obtained modified alumina is 21-700m after roasting treatment at 600-1400 DEG C 2 Per gram, pore volume of 0.2-4.0cm 3 /g; preferably, the specific surface area of the obtained modified alumina is 100-650m after roasting treatment at 600-1200 DEG C 2 Per gram, pore volume of 1-3.6cm 3 /g。
In the present invention, specifically:
after roasting at 600 ℃, the pore volume of the modified alumina is not less than 2.8cm 3 Per gram, specific surface area not less than 500m 2 /g; preferably, the pore volume is from 2.8 to 3.8cm 3 Per gram, specific surface area of 500-650m 2 /g; more preferably, the pore volume is from 2.85 to 3.58cm 3 Per gram, specific surface area of 502-619.2m 2 /g。
After roasting at 800 ℃, the pore volume of the modified alumina is not less than 2.0cm 3 Per gram, specific surface area not less than 400m 2 /g; preferably, the pore volume is from 2.0 to 2.9cm 3 Per gram, specific surface area of 400-499m 2 /g; more preferably, the pore volume is from 2.2 to 2.69cm 3 Per gram, specific surface area of 405.3-495.8m 2 /g。
After roasting at 1000 ℃, the pore volume of the modified alumina is not less than 1.0cm 3 Per gram, specific surface area not less than 200m 2 /g; preferably, the pore volume is 1-1.95cm 3 Per gram, specific surface area of 200-399m 2 /g; more preferably, the pore volume is 1.18-1.92cm 3 Per gram, specific surface area of 200-399m 2 /g。
After roasting at 1200 ℃, the pore volume of the modified alumina is not less than 0.8cm 3 Per gram, specific surface area not less than 100m 2 /g; preferably, the pore volume is 0.8-0.9cm 3 Per gram, specific surface area of 100-199m 2 Preferably, the pore volume is 0.84-0.89cm 3 Per gram, specific surface area of 111.6-142.5m 2 /g。
After roasting at 1300 ℃, the pore volume of the modified alumina is not less than 0.3cm 3 Per gram, specific surface area not less than 50m 2 /g; preferably, the pore volume is from 0.3 to 0.79cm 3 Per gram, specific surface area of 50-99m 2 /g; more preferably, the pore volume is from 0.32 to 0.38cm 3 Per gram, a specific surface area of 52.8-58.2m 2 /g。
After roasting at 1400 ℃, the pore volume of the modified alumina is not less than 0.2cm 3 Per gram, specific surface area not less than 20m 2 /g; preferably, the pore volume is from 0.2 to 0.29cm 3 Per gram, specific surface area of 20-49m 2 /g; more preferably, the pore volume is from 0.2 to 0.25cm 3 Per gram, specific surface area of 21.1-27.3m 2 /g。
The present invention will be described in detail by examples.
In the following examples and comparative examples:
specific surface area and pore volume parameters were measured by TriStar II 3020, micromeritics, USA;
the raw materials are aluminum sulfate octadecatydrate, sodium hydroxide, dodecahydrate and disodium hydrogen phosphate which are all analytically pure and purchased from the company of the chemical plant of the ridge; water glass was purchased from medium petrochemical catalyst company.
Example 1
This example illustrates a modified alumina having high thermal stability prepared by the process of the present invention.
(1) Mixing sodium hydroxide, aluminum hydroxide and deionized water, and reacting for 3 hours at 140 ℃ to obtain sodium metaaluminate solution with the sodium-aluminum ratio (molar ratio) of 4.5 and the aluminum content of 6.4 weight percent calculated by aluminum oxide;
(2) Dissolving aluminum sulfate solid into deionized water to obtain aluminum sulfate solution with the concentration of 0.2mol/kg, and then mixing the aluminum sulfate solution with the sodium metaaluminate solution; then, dropwise adding a water glass solution and a disodium hydrogen phosphate solution so that Si is Al=0.07 and P is Al=0.18, wherein the pH is kept to be 9 in the dropwise adding process;
(3) Then crystallizing the obtained mixed solution for 10 hours at 170 ℃; then naturally cooling to obtain slurry; filtering the obtained slurry to obtain a filter cake, washing the filter cake with deionized water for 3 times, and drying in an oven at 140 ℃ for 3 hours to obtain the modified boehmite with the specific surface area of 684.6m 2 Per gram, pore volume of 3.87cm 3 /g；
(4) The modified boehmite obtained above was calcined at different temperatures for 2 hours to obtain modified alumina, the specific surface area and pore volume data of which are shown in table 1, and table 1 is the specific surface area and pore volume of the modified alumina prepared at different calcining temperatures.
TABLE 1
Example 2
This example illustrates a modified alumina having high thermal stability prepared by the process of the present invention.
(1) Mixing sodium hydroxide, aluminum hydroxide and deionized water, and reacting for 4 hours at 120 ℃ to obtain sodium metaaluminate solution with the sodium-aluminum ratio (molar ratio) of 4 and the aluminum content of 6 weight percent calculated by aluminum oxide;
(2) Dissolving aluminum sulfate solid into deionized water to obtain aluminum sulfate solution with the concentration of 0.7mol/kg, and then mixing the aluminum sulfate solution with the sodium metaaluminate solution; then, dropwise adding a water glass solution and a disodium hydrogen phosphate solution so that Si is Al=0.15 and P is Al=0.09, wherein the pH value is kept to be 8.5 in the dropwise adding process;
(3) Then crystallizing the obtained mixed solution for 20 hours at 150 ℃; then naturally cooling to obtain slurry; filtering the obtained slurry to obtain a filter cake and a filtrate, washing the filter cake with deionized water for 2 times, and drying in an oven at 120 ℃ for 4 hours to obtain modified boehmite with a specific surface area of 610.8m 2 Per gram, pore volume of 3.36cm 3 /g；
(4) The modified boehmite obtained above was calcined at different temperatures for 10 hours to obtain modified alumina, the specific surface area and pore volume data of which are shown in table 2, and table 2 shows the specific surface area and pore volume of the modified alumina prepared at different calcining temperatures.
TABLE 2
Example 3
This example illustrates a modified alumina having high thermal stability prepared by the process of the present invention.
(1) Mixing sodium hydroxide, aluminum hydroxide and deionized water, and reacting for 2 hours at 160 ℃ to obtain sodium metaaluminate solution with the sodium-aluminum ratio (molar ratio) of 4.8 and the aluminum content of 7 weight percent calculated by aluminum oxide;
(2) Dissolving aluminum sulfate solid into deionized water to obtain aluminum sulfate solution with the concentration of 0.4mol/kg, and then mixing the aluminum sulfate solution with the sodium metaaluminate solution; then, a water glass solution and a disodium hydrogen phosphate solution were added dropwise. So that Si: al=0.02, p: al=0.41, the dropping process maintained pH at 9.5;
(3) Then crystallizing the obtained mixed solution for 2 hours at 210 ℃; then naturally cooling to obtain slurry; filtering the obtained slurry to obtain a filter cake and a filtrate, washing the filter cake with deionized water for 4 times, and drying in an oven at 130 ℃ for 3 hours to obtain a modified productBoehmite of 590.4m specific surface area 2 Per gram, pore volume of 3.32cm 3 /g；
(4) The modified boehmite obtained above was calcined at different temperatures for 14 hours to obtain modified alumina, the specific surface area and pore volume data of which are shown in table 3, and table 3 shows the specific surface area and pore volume of the modified alumina prepared at different calcining temperatures.
TABLE 3 Table 3
Example 4
This example illustrates a modified alumina having high thermal stability prepared by the process of the present invention.
(1) Mixing sodium hydroxide, aluminum hydroxide and deionized water, and reacting for 2 hours at 140 ℃ to obtain sodium metaaluminate solution with the sodium-aluminum ratio (molar ratio) of 5.5 and the aluminum content of 10 weight percent calculated by aluminum oxide;
(2) Dissolving aluminum sulfate solid into deionized water to obtain aluminum sulfate solution with the concentration of 0.5mol/kg, and then mixing the aluminum sulfate solution with the sodium metaaluminate solution; then, dropwise adding a water glass solution and a disodium hydrogen phosphate solution to ensure that Si is Al=0.04 and P is Al=0.29, wherein the pH value is kept to fluctuate within a certain range in the dropwise adding process, and the pH value is 9;
(3) Then crystallizing the obtained mixed solution for 8 hours at 180 ℃; then naturally cooling to obtain slurry; filtering the obtained slurry to obtain a filter cake and a filtrate, washing the filter cake with deionized water for 2 times, and drying in an oven at 140 ℃ for 4 hours to obtain modified boehmite with a specific surface area of 517.9m 2 Per gram, pore volume of 3.17cm 3 /g；
(4) The modified boehmite obtained above was calcined at different temperatures for 6 hours to obtain modified alumina, the specific surface area and pore volume data of which are shown in table 4, and table 4 shows the specific surface area and pore volume of the modified alumina prepared at different calcining temperatures.
TABLE 4 Table 4
Example 5
This example illustrates a modified alumina having high thermal stability prepared by the process of the present invention.
(1) Mixing sodium hydroxide, aluminum hydroxide and deionized water, and reacting for 2 hours at 140 ℃ to obtain sodium metaaluminate solution with the sodium-aluminum ratio (molar ratio) of 4.5 and the aluminum content of 6.4 weight percent calculated by aluminum oxide;
(2) Dissolving aluminum sulfate solid into deionized water to obtain aluminum sulfate solution with the concentration of 0.3mol/kg, and then mixing the aluminum sulfate solution with the sodium metaaluminate solution; then, dropwise adding a water glass solution and a disodium hydrogen phosphate solution to ensure that Si is Al=0.11 and P is Al=0.12, wherein the pH value is kept to fluctuate within a certain range in the dropwise adding process, and the pH value is 9;
(3) Then crystallizing the obtained mixed solution for 8 hours at 180 ℃; then naturally cooling to obtain slurry; filtering the obtained slurry to obtain a filter cake and a filtrate, washing the filter cake with deionized water for 2 times, and drying in an oven at 140 ℃ for 4 hours to obtain modified boehmite with a specific surface area of 588.3m 2 Per gram, pore volume of 3.43cm 3 /g；
(4) The modified boehmite obtained above was calcined at different temperatures for 20 hours to obtain modified alumina, the specific surface area and pore volume data of which are shown in table 5, and table 5 shows the specific surface area and pore volume of the modified alumina prepared at different calcining temperatures.
TABLE 5
Example 6
This example illustrates a modified alumina having high thermal stability prepared by the process of the present invention.
(1) Mixing sodium hydroxide, aluminum hydroxide and deionized water, and reacting for 2 hours at 140 ℃ to obtain sodium metaaluminate solution with the sodium-aluminum ratio (molar ratio) of 5.5 and the aluminum content of 10 weight percent calculated by aluminum oxide;
(2) Dissolving aluminum sulfate solid into deionized water to obtain aluminum sulfate solution with the concentration of 0.6mol/kg, and then mixing the aluminum sulfate solution with the sodium metaaluminate solution; then water glass solution and disodium hydrogen phosphate solution are added dropwise so that Si is Al=0.13, P is Al=0.36, the pH value is kept to fluctuate within a certain range in the dropping process, and the pH value is 8.6;
(3) Then crystallizing the obtained mixed solution for 8 hours at 180 ℃; then naturally cooling to obtain slurry; filtering the obtained slurry to obtain a filter cake and a filtrate, washing the filter cake with deionized water for 2 times, and drying in an oven at 140 ℃ for 4 hours to obtain modified boehmite with a specific surface area of 505.3m 2 Per gram, pore volume of 3.21cm 3 /g；
(4) The modified boehmite obtained above was calcined at different temperatures for 6 hours to obtain modified alumina, the specific surface area and pore volume data of which are shown in table 6, and table 6 is the specific surface area and pore volume of the modified alumina prepared at different calcining temperatures.
TABLE 6
Comparative example 1
Alumina was prepared in the same manner as in example 1 except that: disodium hydrogen phosphate solution and water glass are not added;
the specific surface area of the prepared modified boehmite is 704.4m 2 Per gram, pore volume of 2.68cm 3 /g。
The unmodified alumina obtained is shown in Table 7, and Table 7 shows the specific surface area and pore volume of the modified alumina prepared at different calcination temperatures.
TABLE 7
Comparative example 2
Alumina was prepared in the same manner as in example 1 except that: the pH was 7.5.
The specific surface area of the prepared modified boehmite is 512.4m 2 Per gram, pore volume of 3.08cm 3 /g。
The resulting modified alumina is shown in Table 8, and Table 8 shows the specific surface area and pore volume of the modified alumina prepared at different firing temperatures.
TABLE 8
Comparative example 3
Alumina was prepared in the same manner as in example 1 except that: the crystallization temperature was 270 ℃.
The specific surface area of the prepared modified boehmite is 498.3m 2 Per gram, pore volume of 2.95cm 3 /g。
The resulting modified alumina is shown in Table 9, and Table 9 shows the specific surface area and pore volume of the modified alumina prepared at different firing temperatures.
TABLE 9
Comparative example 4
Alumina was prepared in the same manner as in example 1 except that: and (3) adding sodium hydrogen phosphate solution, mixing and crystallizing the aluminum sulfate solution and the sodium metaaluminate solution, and then adding water glass.
The specific surface area of the prepared modified boehmite is 549.1m 2 Per gram, pore volume of 2.84cm 3 /g。
The resulting modified alumina is shown in Table 10, and Table 10 shows the specific surface area and pore volume of the modified alumina prepared at different firing temperatures.
Table 10
Comparative example 5
Alumina was prepared in the same manner as in example 1 except that: the molar ratio of silicon, phosphorus and aluminum was 0.42:0.9:1.
the specific surface area of the prepared modified boehmite is 475.2m 2 Per gram, pore volume of 2.74cm 3 /g。
The resulting modified alumina is shown in Table 11, and Table 11 shows the specific surface area and pore volume of the modified alumina prepared at different firing temperatures.
TABLE 11
According to the embodiment and the comparative example, the embodiment of the technical scheme of the invention can obtain the macroporous large specific surface area modified alumina with high thermal stability, and the production process is green and clean. The unmodified alumina obtained in the comparative example has a certain similarity in performance with the modified alumina obtained in the examples, but has poor thermal stability and a too small specific surface area.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (10)
1. The preparation method of the modified alumina with high thermal stability is characterized by comprising the following steps:
(1) Dropwise adding water glass and a phosphate-containing compound into a mixed solution of an aluminum sulfate solution and a sodium metaaluminate solution to obtain a mixed solution;
(2) Crystallizing the mixed solution to obtain slurry; filtering, washing and drying the slurry to obtain modified boehmite;
(3) Roasting the modified boehmite at 600-1400 ℃ to obtain the modified alumina.
2. The production method according to claim 1, wherein the conditions of calcination include: the temperature is 600-1200 ℃ and the time is 1-20h.
3. The preparation method according to claim 1, wherein in step (2), the pH of the mixed solution is 8 to 11, preferably 8.5 to 9.5;
and/or, the crystallization conditions include: the temperature is 50-230 ℃ and the time is 1-100h.
4. The preparation method according to claim 1, wherein the sodium metaaluminate solution has an aluminum content of 5 to 10wt% in terms of aluminum oxide, and a molar ratio of sodium to aluminum of 3 to 5.5;
preferably, the sodium metaaluminate solution has an aluminum content of 6-7wt% in terms of aluminum oxide, and a molar ratio of sodium to aluminum of 4-4.8.
5. The preparation method according to claim 1 or 4, wherein the preparation method of the sodium metaaluminate solution comprises: the sodium hydroxide, the aluminum hydroxide and the water react to obtain the catalyst;
preferably, the reaction conditions include: the temperature is 120-160 ℃ and the time is 2-5h.
6. The preparation method according to claim 1, wherein the phosphate group-containing compound comprises one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate and potassium dihydrogen phosphate; preferably disodium hydrogen phosphate;
and/or the concentration of the aluminum sulfate solution is 0.1-0.7mol/kg.
7. The preparation method according to claim 1, wherein the modified boehmite has a specific surface area of 500-800m 2 Per gram, pore volume of 3-4cm 3 /g。
8. The production method according to any one of claims 1 to 7, wherein a molar ratio of the silicon content in terms of elemental silicon, the phosphorus content in terms of elemental phosphorus in the phosphate-containing compound, and the total aluminum content in terms of elemental aluminum in the sodium metaaluminate and the aluminum sulfate is (0.01 to 0.21): (0.02 to 0.71): 1;
preferably, the molar ratio of silicon, phosphorus and aluminum is (0.02-0.15): (0.03-0.41): 1.
9. A modified alumina having high thermal stability, which is produced by the production method according to any one of claims 1 to 8.
10. The modified alumina according to claim 9, wherein the modified alumina has a specific surface area of 21-700m 2 Per gram, pore volume of 0.2-4cm 3 /g；
Preferably, the specific surface area of the modified alumina is 100-650m 2 Per gram, pore volume of 1-3.6cm 3 /g。
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