CN113877568B - Porous high-temperature-resistant catalyst and preparation method thereof - Google Patents
Porous high-temperature-resistant catalyst and preparation method thereof Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 76
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 239000011148 porous material Substances 0.000 claims abstract description 12
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 7
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000000243 solution Substances 0.000 claims description 78
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 42
- 238000003756 stirring Methods 0.000 claims description 29
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 28
- 238000010438 heat treatment Methods 0.000 claims description 20
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 18
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 claims description 16
- 238000001354 calcination Methods 0.000 claims description 14
- 239000003795 chemical substances by application Substances 0.000 claims description 14
- 239000000843 powder Substances 0.000 claims description 13
- VQWFNAGFNGABOH-UHFFFAOYSA-K chromium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Cr+3] VQWFNAGFNGABOH-UHFFFAOYSA-K 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 239000007864 aqueous solution Substances 0.000 claims description 10
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 10
- 239000000920 calcium hydroxide Substances 0.000 claims description 10
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 10
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 9
- 239000007788 liquid Substances 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- 239000005711 Benzoic acid Substances 0.000 claims description 8
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims description 8
- 235000010233 benzoic acid Nutrition 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 8
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 8
- 235000019345 sodium thiosulphate Nutrition 0.000 claims description 8
- 239000002253 acid Substances 0.000 claims description 6
- DTDCCPMQHXRFFI-UHFFFAOYSA-N dioxido(dioxo)chromium lanthanum(3+) Chemical compound [La+3].[La+3].[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O DTDCCPMQHXRFFI-UHFFFAOYSA-N 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 5
- 239000003513 alkali Substances 0.000 claims description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 3
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 239000011975 tartaric acid Substances 0.000 claims description 3
- 235000002906 tartaric acid Nutrition 0.000 claims description 3
- 238000009736 wetting Methods 0.000 claims description 3
- 239000012670 alkaline solution Substances 0.000 claims description 2
- 229910052723 transition metal Inorganic materials 0.000 abstract description 12
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 abstract description 4
- 239000011575 calcium Substances 0.000 abstract description 4
- 229910052791 calcium Inorganic materials 0.000 abstract description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 abstract description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 abstract description 3
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052802 copper Inorganic materials 0.000 abstract description 3
- 239000010949 copper Substances 0.000 abstract description 3
- 239000011777 magnesium Substances 0.000 abstract description 3
- 229910052749 magnesium Inorganic materials 0.000 abstract description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 16
- 230000003197 catalytic effect Effects 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000009826 distribution Methods 0.000 description 6
- XZUAPPXGIFNDRA-UHFFFAOYSA-N ethane-1,2-diamine;hydrate Chemical compound O.NCCN XZUAPPXGIFNDRA-UHFFFAOYSA-N 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 238000002336 sorption--desorption measurement Methods 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 210000001161 mammalian embryo Anatomy 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000013335 mesoporous material Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- WKXHZKXPFJNBIY-UHFFFAOYSA-N titanium tungsten vanadium Chemical group [Ti][W][V] WKXHZKXPFJNBIY-UHFFFAOYSA-N 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/24—Chromium, molybdenum or tungsten
- B01J23/26—Chromium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8628—Processes characterised by a specific catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Catalysts (AREA)
Abstract
The technical scheme of the invention discloses a porous high-temperature-resistant catalyst and a preparation method thereof, wherein the porous high-temperature-resistant catalyst takes lanthanum perovskite chromate as a carrier and is doped with transition metal elements, the mass of the transition metal elements is 2-18% of the total mass of the porous high-temperature-resistant catalyst, and the transition metal elements comprise at least one of calcium, magnesium and copper. The porous high-temperature-resistant catalyst has better stability and more pore channels, and can not be deactivated in a high-temperature environment.
Description
Technical Field
The invention belongs to the field of atmospheric environment treatment, and particularly relates to a porous high-temperature-resistant catalyst and a preparation method thereof.
Background
Nitrogen oxides (NOx) are atmospheric pollutants, mainly NO and NO 2. Nitrogen oxides in air are mainly derived from natural sources, but most of nitrogen oxides in urban atmosphere come from fossil fuel combustion, automobile and ship moving sources, industrial boilers and the like.
For the treatment of nitrogen oxides, a Selective Catalytic Reduction (SCR) flue gas denitration technology is considered as the most effective technology for removing NOx, the core technology is a catalyst, the current common SCR catalyst is a vanadium-tungsten-titanium catalyst, the catalyst has a good catalytic effect, but the working temperature range of the catalyst is limited to be larger, and the catalyst is easy to deactivate above 450 ℃; in addition, vanadium has larger biotoxicity and has certain danger.
Disclosure of Invention
The technical scheme of the invention aims to solve the technical problem of providing the porous high-temperature-resistant catalyst and the preparation method thereof, and the porous high-temperature-resistant catalyst has better stability and more pore channels and cannot be deactivated in a high-temperature environment.
In order to solve the technical problems, the technical scheme of the invention provides a preparation method of a porous high-temperature-resistant catalyst, which comprises the following steps: dissolving chromium hydroxide in a sodium hydroxide solution, and adding lanthanum oxide powder to obtain a solid-liquid mixed solution; adjusting the pH value of the solid-liquid mixed solution to 12-14 by adopting acid liquor, heating to 90-97 ℃, and stirring for 10-15 hours to prepare a first solution; dissolving anhydrous ethylenediamine and sodium thiosulfate in water, heating to 70-95 ℃, adding phenol and benzoic acid while stirring, stopping stirring after dissolving, and standing at 70-95 ℃ for at least 12 hours to prepare a porous structure template agent; dropwise adding the porous structure template agent into the first solution, keeping the temperature of the first solution at 70-95 ℃ and reducing the pH value of the first solution to 6-8 to prepare a second solution; heating the second solution for 4-8 hours at 180-220 ℃, and adopting alkali liquor to adjust the pH value of the second solution to 9-10 to prepare a third solution; adding calcium hydroxide into the third solution, uniformly stirring, filtering, washing with water, and drying to prepare a catalyst blank; dripping ethylenediamine water solution with mass fraction of 8-10% on the catalyst blank for wetting, performing anaerobic calcination at 1100-1300 ℃ for 12-16 hours, then reducing the temperature to 650-700 ℃, and performing calcination at air atmosphere for 12-16 hours to obtain the porous high temperature resistant catalyst.
Optionally, the concentration of the sodium hydroxide solution is 1.2-1.7 mol/L, and the molar mass ratio of the chromium hydroxide to the lanthanum oxide is 1 (1-1.05).
Optionally, the acid solution includes citric acid solution or tartaric acid solution.
Optionally, the method for preparing the porous structure template agent comprises the following steps: preparing 3-4 mL of anhydrous ethylenediamine and 2.7-3.5 g of sodium thiosulfate into 100mL of aqueous solution, heating the aqueous solution to 70-95 ℃, adding 2-5 mL of phenol and 5.5-8.7 g of benzoic acid while stirring, stopping stirring after all the components are dissolved, and standing at 70-95 ℃ for more than 12 hours.
Optionally, the alkali solution comprises sodium hydroxide solution or potassium hydroxide solution.
Optionally, the molar ratio of the calcium element in the calcium hydroxide to the lanthanum element in the lanthanum oxide powder is 1 (1-4).
The invention also provides a porous high-temperature-resistant catalyst, which takes lanthanum perovskite chromate as a carrier and is doped with transition metal elements, wherein the mass of the transition metal elements is 2-18% of the total mass of the porous high-temperature-resistant catalyst, and the transition metal elements comprise at least one of calcium, magnesium and copper.
Optionally, the average pore diameter of the porous high temperature resistant catalyst is 1.478-1.766 nm, and the specific surface area is 0.540-0.728 m 2/g.
Optionally, the particle size of the porous high temperature resistant catalyst is 120-300 nm.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
compared with the existing synthesis method of the SCR catalyst, the preparation method of the technical scheme of the invention has the advantages of simple process, mild reaction conditions and higher synthesis conversion rate.
Compared with the existing SCR catalyst, the porous high-temperature-resistant catalyst has better stability and can ensure extremely high catalytic efficiency after being calcined at a high temperature of 600 ℃.
Compared with the existing SCR catalyst, the porous high-temperature-resistant catalyst provided by the technical scheme of the invention has more microporous mesoporous structures, larger specific surface area and better catalytic effect.
Compared with the existing SCR catalyst, the porous high-temperature-resistant catalyst has the advantages of lower synthesis cost and good catalyst stability, and can be applied to more conditions.
Drawings
FIG. 1 is an XRD pattern for a porous high temperature resistant SCR catalyst of example 1;
FIG. 2 is an N 2 adsorption-desorption isothermal curve and pore size distribution plot for the porous high temperature resistant SCR catalyst of example 1;
FIG. 3 is a graph of the catalytic effect of the porous high temperature SCR catalyst of example 1 on NO 2;
FIG. 4 is a graph of the catalytic effect of the porous high temperature SCR catalyst of example 1 on NO 2 at 280℃after calcination at 600℃for 30 hours.
Detailed Description
In order that those skilled in the art will better understand the technical solutions of the present application, the present application will be further described with reference to the following examples, and it is apparent that the described examples are only some, but not all, examples of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, shall fall within the scope of the application.
The embodiment of the invention provides a preparation method of a porous high-temperature-resistant catalyst, which comprises the following steps:
S1, dissolving chromium hydroxide in a sodium hydroxide solution, and adding lanthanum oxide powder to obtain a solid-liquid mixed solution;
S2, adjusting the pH value of the solid-liquid mixed solution to 12-14 by adopting acid liquor, heating to 90-97 ℃, and stirring for 10-15 hours to prepare a first solution;
Step S3, dissolving anhydrous ethylenediamine and sodium thiosulfate in water, heating to 70-95 ℃, adding phenol and benzoic acid while stirring, stopping stirring after dissolving, and standing at 70-95 ℃ for at least 12 hours to prepare a porous structure template agent;
step S4, dropwise adding the porous structure template agent into the first solution, keeping the temperature of the first solution at 70-95 ℃ and reducing the pH value of the first solution to 6-8 to prepare a second solution;
step S5, heating the second solution for 4-8 hours at 180-220 ℃, and adopting alkali liquor to adjust the pH value of the second solution to 9-10 to prepare a third solution;
Step S6, adding calcium hydroxide into the third solution, uniformly stirring, filtering, washing with water, and drying to prepare a catalyst blank;
And S7, dripping an ethylenediamine water solution with the mass fraction of 8-10% on the catalyst blank for wetting, performing anaerobic calcination at 1100-1300 ℃ for 12-16 hours, then reducing the temperature to 650-700 ℃, and performing calcination at air atmosphere for 12-16 hours to obtain the porous high-temperature-resistant catalyst.
In other embodiments, the order of steps S1 to S3 may be exchanged with each other.
In some embodiments, the concentration of the sodium hydroxide solution may be 1.2 to 1.7mol/L, and the molar mass ratio of the chromium hydroxide to the lanthanum oxide is 1 (1 to 1.05). In other embodiments, the corresponding mass of lanthanum oxide and chromium hydroxide may also be weighed according to the mass ratio of lanthanum element to chromium element in the catalyst component.
In some embodiments, the acid solution that adjusts the pH of the solid-liquid mixture may include a citric acid solution or a tartaric acid solution. The concentration of the citric acid solution may be 0.1 to 2mol/L.
In some embodiments, a method of making a porous structure templating agent may include: preparing 3-4 mL of anhydrous ethylenediamine and 2.7-3.5 g of sodium thiosulfate into 100mL of aqueous solution, heating the aqueous solution to 70-95 ℃, adding 2-5 mL of phenol and 5.5-8.7 g of benzoic acid while stirring, stopping stirring after all the components are dissolved, and standing at 70-95 ℃ for more than 12 hours.
In some embodiments, the alkaline solution used in adjusting the pH of the second solution may comprise a sodium hydroxide solution or a potassium hydroxide solution, wherein the concentration of the sodium hydroxide solution may be 0.1 to 3mol/L.
In some embodiments, calcium hydroxide is added to the third solution at a molar ratio of calcium element in the calcium hydroxide to lanthanum element in the lanthanum oxide powder of 1 (1-4). After adding calcium hydroxide, stirring uniformly, filtering, washing with water, and drying at 110-200 ℃.
In some embodiments, a proper amount of catalyst blank powder is taken for tabletting and molding, then an ethylenediamine water solution with the mass fraction of 8-10% is dripped on each sample piece to moisten the sample piece, and then the moistened sample piece is placed in an atmosphere furnace and is subjected to anaerobic calcination for 12 hours at the high temperature of 1100-1300 ℃; then the temperature is reduced to 650-700 ℃ and calcined for 12 hours in the air atmosphere; and grinding and washing after the calcination is finished, and drying to obtain the lanthanum chromate perovskite supported transition metal porous high-temperature-resistant catalyst.
The step S1 and the step S2 of the embodiment of the invention can lead the distribution of reaction molecules to be more uniform, thereby increasing the reaction synthesis rate. When the step S7 is carried out, the template agent is used, so that the pore canal distribution is more uniform, and the material has a better pore structure during synthesis. And S7, performing secondary high-temperature calcination to ensure that the stability of the material can be improved and the high specific surface area and uniform pore channel distribution are maintained at high temperature.
The embodiment of the invention also provides a porous high-temperature-resistant catalyst, which can be prepared by the preparation method. The porous high-temperature-resistant catalyst takes lanthanum perovskite chromate as a carrier and is doped with transition metal elements, wherein the mass of the transition metal elements is 2-18% of the total mass of the porous high-temperature-resistant catalyst, and the transition metal elements comprise at least one of calcium, magnesium and copper.
In some embodiments, the porous high temperature resistant catalyst has an average pore size of 1.478 to 1.766nm and a specific surface area of 0.540 to 0.728m 2/g. In some embodiments, the porous high temperature resistant catalyst is particulate and has a particle size of 120 to 300nm.
The porous high temperature resistant catalyst and the preparation method thereof according to the embodiments of the present invention are further described below by way of some specific examples.
Example 1
(1) Taking 5.22g of lanthanum oxide and 2.06g of chromium hydroxide; dissolving chromium hydroxide in 100ml of sodium hydroxide solution with the concentration of 1.2mol/L, adding lanthanum oxide powder to prepare solid-liquid mixed solution, adjusting the pH value to 14 by using citric acid solution, heating to 90 ℃ in a water bath, heating and stirring for 15 hours to prepare solution A.
(2) Preparing a 100mL aqueous solution from 4mL anhydrous ethylenediamine and 3.5g sodium thiosulfate; then the solution was heated to 95℃and 5mL of phenol liquid and 8.7g of benzoic acid were added with stirring, and after all of them were dissolved, stirring was stopped, and the mixture was allowed to stand at 95℃for 12 hours to obtain a porous template.
(3) And (3) dropwise adding the porous structure template agent into the solution A, adjusting the pH value of the solution A to 8 by using the porous structure template agent, and stirring to prepare a solution B. Putting the solution B into a reaction kettle, and heating for 8 hours at 180 ℃ by using a muffle furnace; after the heating, cooling to room temperature, adjusting the pH value to 10 by using a sodium hydroxide solution with the concentration of 0.1mol/L, adding 0.15g of calcium hydroxide powder into the solution, stirring uniformly, filtering, washing with water, and drying at 110 ℃ to prepare a catalyst embryo body.
(4) Tabletting the catalyst blank powder to form, then dripping an ethylenediamine water solution with the mass fraction of 10% on each sample piece to moisten the sample pieces, and then placing the moistened sample pieces in an atmosphere furnace to perform anaerobic calcination for 12 hours at the high temperature of 1300 ℃; then the temperature is reduced to 700 ℃, and the mixture is calcined for 12 hours in the air atmosphere; and grinding and washing after the calcination is finished, and drying to obtain the lanthanum chromate perovskite supported transition metal porous high-temperature-resistant SCR catalyst.
Example 2
(1) Taking 6.85g of lanthanum oxide and 3.09g of chromium hydroxide; dissolving chromium hydroxide in 100mL of 1.4mol/L sodium hydroxide solution, adding lanthanum oxide powder to prepare solid-liquid mixed solution, adjusting the pH value to 14 by using citric acid solution, heating to 85 ℃ in a water bath, heating and stirring for 15 hours to prepare solution A.
(2) Preparing a 100mL aqueous solution from 4mL anhydrous ethylenediamine and 3.5g sodium thiosulfate; then the solution was heated to 95℃and 5mL of phenol liquid and 8.7g of benzoic acid were added with stirring, and after all of them were dissolved, stirring was stopped, and the mixture was allowed to stand at 95℃for 12 hours to obtain a porous template.
(3) And (3) dropwise adding the porous structure template agent into the solution A, adjusting the pH value of the solution A to 7 by using the porous structure template agent, and stirring to prepare a solution B. Putting the solution B into a reaction kettle, and heating for 6 hours at 180 ℃ by using a muffle furnace; after the heating, cooling to room temperature, adjusting the pH value to 10 by using a sodium hydroxide solution with the concentration of 0.1mol/L, adding 0.22g of calcium hydroxide powder into the solution, stirring uniformly, filtering, washing with water, and drying at 110 ℃ to prepare a catalyst embryo body.
(4) Tabletting the catalyst blank powder to form, then dripping an ethylenediamine water solution with the mass fraction of 10% on each sample piece to moisten the sample pieces, and then placing the moistened sample pieces in an atmosphere furnace to perform anaerobic calcination for 12 hours at the high temperature of 1300 ℃; then the temperature is reduced to 700 ℃, and the mixture is calcined for 12 hours in the air atmosphere; grinding and washing after the calcination is finished, and drying to obtain the porous high-temperature-resistant catalyst of the lanthanum chromate perovskite supported transition metal.
Fig. 1 is an XRD pattern of the porous high temperature resistant SCR catalyst of example 1, and it can be seen from the figure that the main components of the catalyst are calcium doped lanthanum chromate and lanthanum chromate, in which a very small amount of chromium oxide is contained, and the main component is perovskite structure.
Fig. 2 is an N 2 adsorption-desorption isothermal curve and a pore size distribution diagram of the porous high temperature resistant SCR catalyst of example 1, and the classification standard according to international society of theory and application of chemistry (IUPAC) belongs to Langmuir type IV, and in addition, the slope of the adsorption-desorption curve suddenly rises in a high pressure area, which indicates that an obvious H1 hysteresis loop exists, which indicates that the catalyst is a mesoporous material, the pore size distribution is uneven, a multi-stage pore structure exists, and the catalyst material is aggregated by a rigid ion set or is uniformly distributed in spherical particles.
Fig. 3 is a graph of the catalytic effect of the porous high temperature SCR catalyst of example 1 on NO 2, where C (%) is the conversion of NO 2, the starting concentration of NO 2 is 1000ppm, and the space velocity is ghsv=10600 h -1. It can be seen from the graph that under this condition, the conversion rate of NO 2 is close to 50% at 230 ℃ and the conversion rate of NO 2 is close to 100% at 280 ℃, and the catalytic activity on NO 2 is higher.
Fig. 4 is a graph of the catalytic effect of porous high temperature SCR catalyst of example 1 on NO 2 at 280 ℃ after calcination at 600 ℃ for 30 hours, where the initial concentration of NO 2 is 1000ppm, space velocity ghsv=10600 h -1. The graph shows that the catalyst calcined at 600 ℃ has NO 2% or more at 280 ℃ and is close to 100%, which shows that the catalyst can not be deactivated at 600 ℃ and has better catalytic effect.
Although the present invention has been described with respect to the preferred embodiments, it is not intended to limit the invention thereto, and any person skilled in the art may make any possible variations and modifications to the technical solution of the present invention using the methods and techniques disclosed herein without departing from the spirit and scope of the present invention, and therefore any simple modifications, equivalent variations and modifications to the above embodiments according to the technical substance of the present invention fall within the scope of the technical solution of the present invention.
Claims (7)
1. A method for preparing a porous high temperature resistant catalyst, comprising:
dissolving chromium hydroxide in a sodium hydroxide solution, and adding lanthanum oxide powder to obtain a solid-liquid mixed solution;
adjusting the pH value of the solid-liquid mixed solution to 12-14 by adopting acid liquor, heating to 90-97 ℃, and stirring for 10-15 hours to prepare a first solution;
dissolving anhydrous ethylenediamine and sodium thiosulfate in water, heating to 70-95 ℃, adding phenol and benzoic acid while stirring, stopping stirring after dissolving, and standing at 70-95 ℃ for at least 12 hours to prepare a porous structure template agent;
dropwise adding the porous structure template agent into the first solution, keeping the temperature of the first solution at 70-95 ℃ and reducing the pH value of the first solution to 6-8 to prepare a second solution;
Heating the second solution for 4-8 hours at 180-220 ℃, and adjusting the pH value of the second solution to 9-10 by adopting alkali liquor to prepare a third solution;
Adding calcium hydroxide into the third solution, uniformly stirring, filtering, washing with water, and drying to prepare a catalyst blank;
Dripping an ethylenediamine aqueous solution with the mass fraction of 8-10% on the catalyst blank for wetting, performing anaerobic calcination at 1100-1300 ℃ for 12-16 hours, then reducing the temperature to 650-700 ℃, and performing calcination in an air atmosphere for 12-16 hours to obtain a porous high-temperature-resistant catalyst;
the concentration of the sodium hydroxide solution is 1.2-1.7 mol/L, and the molar mass ratio of the chromium hydroxide to the lanthanum oxide is 1 (1-1.05);
the molar ratio of the calcium element in the calcium hydroxide to the lanthanum element in the lanthanum oxide powder is 1 (1-4).
2. The method for preparing a porous refractory catalyst according to claim 1, wherein the acid solution comprises citric acid solution or tartaric acid solution.
3. The method for preparing the porous high temperature resistant catalyst according to claim 1, wherein the method for preparing the porous structure template agent comprises the following steps: preparing 3-4 mL of anhydrous ethylenediamine and 2.7-3.5 g of sodium thiosulfate into 100mL of aqueous solution, heating the aqueous solution to 70-95 ℃, adding 2-5 mL of phenol and 5.5-8.7 g of benzoic acid while stirring, stopping stirring after all the aqueous solution is dissolved, and standing at 70-95 ℃ for more than 12 hours.
4. The method for preparing a porous refractory catalyst according to claim 1, wherein the alkaline solution comprises a sodium hydroxide solution or a potassium hydroxide solution.
5. The porous high-temperature-resistant catalyst prepared by the preparation method of claim 1, wherein lanthanum chromate perovskite is used as a carrier and is doped with calcium element, and the mass of the calcium element is 2-18% of the total mass of the porous high-temperature-resistant catalyst.
6. The porous high temperature resistant catalyst according to claim 5, wherein the porous high temperature resistant catalyst has an average pore diameter of 1.478 to 1.766nm and a specific surface area of 0.540 to 0.728m 2/g.
7. The porous high temperature resistant catalyst according to claim 5, wherein the porous high temperature resistant catalyst has a particle size of 120-300 nm.
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