CN114797841A - Mn (manganese) 4+ And Ce 3+ Preparation method of enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst - Google Patents
Mn (manganese) 4+ And Ce 3+ Preparation method of enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 151
- 239000011572 manganese Substances 0.000 title claims abstract description 50
- 229910003077 Ti−O Inorganic materials 0.000 title claims abstract description 18
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 title claims abstract description 14
- 229910052748 manganese Inorganic materials 0.000 title claims abstract description 7
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 66
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 18
- 239000001301 oxygen Substances 0.000 claims abstract description 18
- 229910052688 Gadolinium Inorganic materials 0.000 claims abstract description 11
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims abstract description 10
- 239000002245 particle Substances 0.000 claims abstract description 10
- 229910010413 TiO 2 Inorganic materials 0.000 claims abstract description 7
- 239000011148 porous material Substances 0.000 claims abstract description 7
- 239000012752 auxiliary agent Substances 0.000 claims abstract description 3
- 238000003756 stirring Methods 0.000 claims description 45
- 239000000725 suspension Substances 0.000 claims description 38
- 239000002002 slurry Substances 0.000 claims description 31
- 239000007921 spray Substances 0.000 claims description 31
- 238000001354 calcination Methods 0.000 claims description 29
- 230000003647 oxidation Effects 0.000 claims description 29
- 238000007254 oxidation reaction Methods 0.000 claims description 29
- 239000000243 solution Substances 0.000 claims description 28
- 239000007787 solid Substances 0.000 claims description 23
- 239000011259 mixed solution Substances 0.000 claims description 21
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 claims description 20
- 238000001035 drying Methods 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 18
- 239000011268 mixed slurry Substances 0.000 claims description 18
- 239000012153 distilled water Substances 0.000 claims description 11
- 238000001704 evaporation Methods 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 10
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 10
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 10
- 150000002910 rare earth metals Chemical class 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- 230000003197 catalytic effect Effects 0.000 claims description 6
- 238000009423 ventilation Methods 0.000 claims description 5
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 claims description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 4
- 230000008020 evaporation Effects 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 239000004480 active ingredient Substances 0.000 claims description 2
- 238000000227 grinding Methods 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 229910052723 transition metal Inorganic materials 0.000 claims description 2
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 claims 1
- 150000001875 compounds Chemical class 0.000 claims 1
- 230000001590 oxidative effect Effects 0.000 abstract description 3
- 238000009776 industrial production Methods 0.000 abstract 1
- 230000001568 sexual effect Effects 0.000 abstract 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 28
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 24
- 238000006243 chemical reaction Methods 0.000 description 24
- 230000000694 effects Effects 0.000 description 19
- 150000002500 ions Chemical class 0.000 description 14
- 239000004408 titanium dioxide Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 12
- HTBAHYGLEFPCLK-UHFFFAOYSA-N [Ti].[Ce].[Mn] Chemical compound [Ti].[Ce].[Mn] HTBAHYGLEFPCLK-UHFFFAOYSA-N 0.000 description 10
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 10
- 238000000498 ball milling Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 238000012512 characterization method Methods 0.000 description 7
- 230000001965 increasing effect Effects 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 4
- 238000005507 spraying Methods 0.000 description 4
- 239000002028 Biomass Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000033116 oxidation-reduction process Effects 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- PZHLJJZYVHASQE-UHFFFAOYSA-N [Mn].[La].[Ti] Chemical compound [Mn].[La].[Ti] PZHLJJZYVHASQE-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- MWFSXYMZCVAQCC-UHFFFAOYSA-N gadolinium(iii) nitrate Chemical compound [Gd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O MWFSXYMZCVAQCC-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 description 2
- -1 manganese-gadolinium-titanium Chemical compound 0.000 description 2
- 231100000572 poisoning Toxicity 0.000 description 2
- 230000000607 poisoning effect Effects 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 238000004056 waste incineration Methods 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000002841 Lewis acid Substances 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 230000002779 inactivation Effects 0.000 description 1
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 1
- 150000007517 lewis acids Chemical class 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000027756 respiratory electron transport chain Effects 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- 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
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
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- 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
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- 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
- B01J23/32—Manganese, technetium or rhenium
- B01J23/34—Manganese
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- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
- B01J35/613—10-100 m2/g
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- B01J35/00—Catalysts, in general, characterised by their form or physical properties
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Abstract
Mn (manganese) 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow temperature denitration catalyst is characterized in that the Mn-M-Ti-O (M ═ Ce, La and Gd) ultralow temperature denitration catalyst is TiO 2 Loading denitration active component and auxiliary agent as carrier and oxidizing Mn with ozone x+ And hydrogen peroxide reduction of Ce 4+ Thus obtaining the product. The catalyst obtained by the invention has appropriate specific surface area (70-90 m) 2 Per g), uniform particle size (1-5 μm), surface Mn 4+ High proportion (47-50%), surface Ce 3+ High ratio (19-25%), high surface activityThe method has the characteristics of large number of sexual oxygen species (45-50%), small average pore diameter (less than 13nm), high hydrothermal stability, wide low-temperature active temperature window (125-400 ℃), good denitration performance and the like, meets the requirements of the high-efficiency denitration SCR catalyst, has controllable product components, simple operation flow, low cost and good stability, and is easy to realize large-scale industrial production.
Description
Technical Field
The invention belongs to the technical field of environmental protection, and particularly relates to Mn 4+ And Ce 3+ A preparation method of an enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst.
Background
Nowadays, the coal-electricity unit occupying 60-70% of the total power generation amount is planned to be completely withdrawn in 2060, and solar energy, wind energy and biomass energy mainly occupy dominant positions. The industries of waste incineration, biomass energy and the like are the way for turning waste into wealth in the whole environment-friendly industry, but the generated flue gas has the particularity of containing acidic substances, low temperature and the like, the existing domestic catalyst cannot meet the temperature requirement of ultralow temperature, the tail gas needs to be subjected to temperature rise treatment, the greenhouse effect is severe, and various ultralow temperature catalysts are monopolized abroad, so that the development of the ultralow temperature denitration catalyst with high efficiency and strong poisoning resistance is urgently needed.
Transition metal oxides have been proven active for the SCR reaction in recent years in various studies, and in particular Mn-based oxide catalysts have been extensively studied for low temperature NH due to their excellent catalytic performance 3 -SCR reaction. The method has the following specific advantages: has outstanding stability and large specific surface area. The manganese oxide is easy to form an oxidation-reduction cycle, so that good low-temperature SCR denitration performance is embodied. Mn is MnO or Mn 2 O 3 、Mn 3 O 4 、Mn 5 O 8 、 MnO 2 Five common valence states, wherein MnO 2 Has better oxygen transfer capacity than other materials and has optimal catalytic efficiency. But single MnO x Catalyst presence N 2 Poor selectivity, easy inactivation and the like. Therefore, other metal oxides need to be doped to modify the silicon nitride, so that the silicon nitride has higher oxidation-reduction capability and acid sites, and has better SCR performance.
The rare earth metal elements (M ═ Ce, La and Gd) in the denitration catalyst mainly exist in the form of a cocatalyst, and the denitration catalyst mainly plays the following roles: cause catalysisThe surface electrons of the catalyst are unbalanced, unsaturated chemical bonds and oxygen vacancies are formed, the concentration of surface adsorbed oxygen is increased, and the oxidizing capability of the catalyst is improved; in addition, more NH can be supplied 3 Adsorption sites, increasing the activity of the catalyst; meanwhile, the thermal stability of the sulfate can be reduced, and the decomposition of the sulfate is promoted, so that the sulfur poisoning resistance of the catalyst is improved. The synergistic effect of Mn and rare earth elements is illustrated by Ce:
1. at Ce 4+ And Ce 3+ Redox shift occurs between them, thereby enhancing MnO x Low temperature activity of, and Ce 4+ /Ce 3+ Higher ratio, Ce 4+ And Ce 3+ The stronger the oxygen storage and release in between, the higher the SCR activity.
2. Provide more NH 3 The adsorption sites, Mn-Ce samples, have higher reducibility and can provide more ammonia adsorption sites on Lewis acid sites.
3. Ce improves the stability of the Mn-based catalyst structure, so that the Mn-based catalyst has larger specific surface area.
To further increase Mn 4+ The redox performance of the catalyst is improved, the Mn-Ce catalyst can be modified by adopting hydrogen peroxide in a form of adding an oxidant, so that the Ce on the surface of the catalyst can be improved 3+ /(Ce 3+ +Ce 4+ ) Indicating that the hydrogen peroxide modification can increase the concentration of surface oxygen vacancies. Meanwhile, Ce species on the surface of the catalyst modified by the hydrogen peroxide are dispersed and enhanced, which is beneficial to improving NH of the catalyst 3 -SCR activity.
Therefore, the ultra-low temperature Mn-based denitration catalyst is developed by adopting the synergistic effect of rare earth metal and Mn-based and modifying the catalyst in a novel oxidation-reduction mode, is expected to solve the problems of large specific surface area, narrow temperature window, less active oxygen species and the like, and realizes ultra-low emission in the fields of waste incineration and biomass energy.
Disclosure of Invention
The invention aims to synthesize Mn 4+ And Ce 3+ An enhanced Mn-M-Ti-O (M ═ Ce, La and Gd) ultra-low temperature denitration catalyst.
In order to achieve the purpose, the invention adopts the following technical scheme:
mn (manganese) 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow temperature denitration catalyst is characterized in that the denitration catalyst is TiO 2 The carrier is loaded with denitration active ingredients and rare earth metal element auxiliaries, and is prepared by ozone oxidation, hydrogen peroxide reduction and calcination. Mn on the surface of the active component after oxidation 4+ The proportion is improved, and the catalytic oxidation performance is enhanced; the reduction of hydrogen peroxide can promote Ce 4+ Reduction to Ce 3+ Increase the surface Ce of the active component 3+ The proportion and the number of surface active oxygen species increase oxygen vacancy and promote electron transfer.
The active component is transition metal element manganese; the auxiliary agent is one of rare earth metal elements of cerium, lanthanum and gadolinium, and cerium is preferred.
The specific surface area of the denitration catalyst is 70-90m 2 Per g, particle size 1-5 μm, surface Mn 4+ 47-50% of surface Ce 3+ The proportion is 19-25%, the number of surface active oxygen species is 45-50%, and the average pore diameter is less than 13 nm; the temperature window of catalytic activity for denitration efficiency reaching more than 97 percent is 125-400 ℃.
The method specifically comprises the following steps:
(1) mixing manganese nitrate solution with M (NO) 3 ) x Adding the solid into distilled water, stirring and dissolving to obtain a mixed solution; wherein M is Ce, La or Gd;
(2) making the catalyst carrier TiO 2 Adding the mixture into the mixed solution, and uniformly stirring to obtain mixed slurry;
(3) adjusting the pH value of the mixed slurry, and continuously stirring at normal temperature to obtain a suspension;
(4) introducing ozone into the suspension while stirring by using a pneumatic stirrer to fully oxidize the suspension;
(5) after the introduction is finished, adding hydrogen peroxide dropwise into the slurry after the ozone oxidation;
(6) continuously stirring for a period of time, and centrifuging and washing for a plurality of times;
(7) drying the washed catalyst;
(8) carrying out temperature programming calcination on the dried product;
(9) grinding the calcined product into powder to obtain the material meeting the requirement.
Manganese nitrate solution having a concentration of 50 wt%, M (NO) 3 ) x Distilled water, TiO 2 The mass ratio of (5.94-6.31): (6.04-7.64): 100: 3.53.
in the step (3), ammonia water with the concentration of 20-30 wt% is adopted to adjust the pH value to 8-10.
In the step (4), the specific method of ozone oxidation is as follows: adopting a pneumatic stirring machine with a convex or concave propeller, arranging a vent hole on a propeller shaft, placing the suspension in the pneumatic stirring machine, and introducing ozone into the suspension through the vent hole while stirring; the rotating speed of the propeller is 10-15r/min, and the ozone ventilation volume is 500 mL/min.
In the step (5), the specific method for dropwise adding the hydrogen peroxide comprises the following steps: and (3) extending a dropper into the bottom of the slurry, and dropwise adding hydrogen peroxide at a dropping speed of 10 seconds per drop.
In the step (7), the drying method is selected from negative pressure drying or spray evaporation: the negative pressure drying method is that a vacuum pump forms a negative pressure state, and the negative pressure state is dried by a drying furnace, a heating chamber, a stirring device, a driving device, a steam device, a filtering device, a condensing device and the like; the spray evaporation method is to pump the catalyst into a spray dryer, atomize the catalyst by a nozzle and spray the atomized catalyst out of the bottom of the spray dryer.
In the step (8), the temperature programming rate is 10 ℃/min, the calcination temperature is 500 ℃ and 550 ℃, and the calcination time is 4 hours.
The invention has the beneficial effects that:
the invention adopts Mn (NO) 3 ) 2 And M (NO) 3 ) x( And M ═ Ce, La and Gd), and then ammonia water is used for adjusting the pH value of the solution to obtain a mixed solution, the mixed solution is subjected to ozone oxidation and hydrogen peroxide reduction, and then the mixed solution is dried by negative pressure drying or spray evaporation, and then the material meeting the requirement of granularity is obtained by calcination and ball milling. The preparation method has the advantages of simple operation, simple and convenient equipment requirement and the like.
Mn prepared by the invention 4+ And Ce 3+ EnhancementIn the type Mn-M-Ti-O (M ═ Ce, La and Gd) ultra-low temperature denitration catalyst, the mass fraction of a manganese nitrate solution is adjusted within the range of 20-30%, and the mass fraction of cerium nitrate (lanthanum and gadolinium) is adjusted within the range of 20-30%. The composite powder has moderate specific surface area (70-90 m) 2 Per g), uniform particle size (1-5 μm), surface Mn 4+ High proportion (47-50%), surface Ce 3+ High proportion (19-25%), more surface active oxygen species (45-50%), small average pore diameter (less than 13nm), high hydrothermal stability, wide low-temperature active temperature window (125-400 ℃), good denitration performance and the like, and meets the requirements of SCR catalyst carriers.
A large number of researches show that rare earth metal elements such as cerium and the like can provide an acid site to ensure the catalytic activity of SCR, can reduce the stability of sulfate, promote the decomposition of the sulfate and improve the SO resistance of the catalyst 2 The ability to be poisoned. In addition, rare earth metal elements such as cerium can bring about a large number of defects of lattice oxygen, and play a role in improving the oxygen storage capacity and enhancing the reducibility of the catalyst. Therefore, the addition of rare earth metal elements such as cerium and the like can improve the stability of the catalyst structure, so that the catalyst has a large specific surface area and provides a large number of active centers for SCR reaction.
Detailed Description
The present invention is further illustrated by the following examples (the reagents used in the examples are chemically pure), it should be noted that the following examples are only illustrative and the present invention is not limited thereto.
Example 1: and (3) preparing the MnCeTi-O ultralow-temperature denitration catalyst with the manganese element content of 24 wt% and the cerium element content of 24 wt%.
Step 1: 6.31g of the manganese nitrate solution and 7.64g of the cerium nitrate solid were dissolved in 100g of distilled water, and stirred for 30 minutes to obtain a mixed solution.
Step 2: 3.53g of catalyst carrier titanium dioxide was added to the mixed solution of step 1, and stirring was continued for 1 hour to obtain a mixed slurry of manganese nitrate, cerium nitrate and titanium dioxide.
And 3, step 3: and (3) slowly dropping an ammonia water solution (analytically pure, with the concentration of 20-30 wt%) into the mixed slurry obtained in the step (2), adjusting the pH value of the solution to 10, and continuously stirring at normal temperature for half an hour to obtain a manganese-cerium-titanium suspension.
And 4, step 4: adopting a pneumatic stirrer with a convex or concave propeller, and arranging a vent hole on the propeller; and (3) placing the stirred manganese-cerium-titanium suspension in a pneumatic stirrer, and introducing ozone into the suspension through a vent hole while performing spiral full stirring to fully oxidize the suspension, wherein the rotating speed of a propeller is 10-15r/min, and the gas introducing amount is 500 mL/min.
And 5: and (3) dropwise adding hydrogen peroxide into the oxidized slurry, wherein a dropper is extended into the bottom of the slurry and is dropwise added, and the dropwise adding speed is controlled to be 10 seconds per drop.
Step 6: and after continuously stirring for a period of time, centrifugally washing the slurry after the oxidation and the reduction are finished for a plurality of times to obtain a relatively wet catalyst solid.
And 7: the obtained catalyst solid is subjected to a spray evaporation method (namely, the catalyst is pumped into a spray dryer and is sprayed out from the bottom of the spray dryer after being atomized by a spray head), the particle size of introduced slurry is 10-20 mu m, the spraying temperature is controlled at 250 ℃ and 300 ℃, and the drying time is effectively reduced.
And 8: and putting the obtained dry material into a muffle furnace for temperature programming and calcining. The calcination temperature is 550 ℃, the heating rate is 10 ℃/min, and the calcination time is 4 hours.
And step 9: and (3) placing the calcined material into a ball mill for ball milling to obtain the MnCeTi-O ultralow-temperature denitration catalyst with the granularity of 1-5 mu m.
Comparative example 1
The MnCeTi denitration catalyst was prepared according to the method of example 1, except that the steps of ozone oxidation and hydrogen peroxide reduction were omitted.
NH of MnCeTi-O ultralow temperature denitration catalyst 3 The SCR reaction activity is shown in Table 1, the denitration conversion rate of the catalyst is kept at 100% in the temperature range of 125-350 ℃, and the denitration conversion rate is always kept at more than 98% below 400 ℃, so that the catalyst has good denitration performance.
TABLE 1 characterization Activity of MnCeTi-O ultra-low temperature denitration catalyst
The XPS ion species analogy of the denitration catalysts prepared in example 1 and comparative example 1 is shown in Table 2, and it is found that Mn is obtained after ozone oxidation and hydrogen peroxide reduction 4+ 、Ce 3+ The proportion of active oxygen species is obviously improved, and low-temperature reduction is facilitated.
TABLE 2 XPS ion species ratio of denitration catalyst
Programmed temperature reduction (H) of MnCeTi-O ultra-low temperature denitration catalyst 2 TPR) hydrogen consumption is shown in Table 3, and it can be seen that the catalyst by ozone oxidation and hydrogen peroxide reduction causes MnO 2 Surface CeO 2 The area of the low-temperature reduction peak is increased, which indicates that the ozone oxidation causes Mn 4+ Increase and reduction of hydrogen peroxide to Ce 3+ Increase and is beneficial to low-temperature reduction.
TABLE 3 temperature programmed reduction (H) of MnCeTi-O ultra-low temperature denitration catalyst 2 TPR) hydrogen consumption
Example 2: and (3) preparing the MnCeTi-O ultralow-temperature denitration catalyst with the manganese element content of 24 wt% and the cerium element content of 24 wt%.
Step 1: 6.31g of the manganese nitrate solution and 7.64g of the cerium nitrate solid were dissolved in 100g of distilled water, and stirred for 30 minutes to obtain a mixed solution.
Step 2: 3.53g of catalyst carrier titanium dioxide was added to the mixed solution of step 1, and stirring was continued for 1 hour to obtain a mixed slurry of manganese nitrate, cerium nitrate and titanium dioxide.
And step 3: and (3) slowly dripping an ammonia water solution (analytically pure, with the concentration of 20-30 wt%) into the mixed slurry obtained in the step (2), adjusting the pH value of the solution to 8, and continuously stirring at normal temperature for half an hour to obtain a manganese-cerium-titanium suspension.
And 4, step 4: adopting a pneumatic stirrer with a convex or concave propeller and arranging a vent hole on the propeller; and (3) placing the stirred manganese-cerium-titanium suspension in a pneumatic stirrer, and introducing ozone into the suspension through a vent hole while performing spiral full stirring to fully oxidize the suspension, wherein the rotating speed of a propeller is 10-15r/min, and the gas introducing amount is 500 mL/min.
And 5: and (3) dropwise adding hydrogen peroxide into the oxidized slurry, wherein a dropper is extended into the bottom of the slurry and is dropwise added, and the dropwise adding speed is controlled to be 10 seconds per drop.
Step 6: and after continuously stirring for a period of time, centrifugally washing the slurry after the oxidation and the reduction are finished for a plurality of times to obtain a relatively wet catalyst solid.
And 7: the obtained catalyst solid is dried by a spray evaporation method, the particle size of the introduced slurry is 10-20 mu m, the spray temperature is controlled at 250 ℃ and 300 ℃, and the drying time is effectively reduced.
And 8: and putting the obtained dry material into a muffle furnace for temperature programming and calcining. The calcination temperature is 550 ℃, the heating rate is 10 ℃/min, and the calcination time is 4 hours.
And step 9: and (3) placing the calcined material into a ball mill for ball milling to obtain the MnCeTi-O ultralow-temperature denitration catalyst with the granularity of 1-5 mu m.
NH of MnCeTi-O ultralow temperature denitration catalyst 3 The SCR reaction activity is shown in Table 4, the denitration conversion rate of the catalyst is kept at 100% in the temperature range of 125-275 ℃, and the denitration conversion rate is always kept at more than 97% below 400 ℃, so that the catalyst has good denitration performance.
TABLE 4 characterization Activity of MnCeTi-O ultra-low temperature denitration catalyst
The XPS ion species analogy of the MnCeTi-O ultra-low temperature denitration catalyst is shown in Table 5, and the comparison of comparative example 1 and example 1 shows Mn after ozone oxidation and hydrogen peroxide reduction 4+ 、Ce 3+ The proportion of active oxygen species is increased and is lower than the catalyst prepared at pH 10, indicating that pH 10 is the optimum pH.
TABLE 5 XPS ion species and active oxygen species number ratio of MnCeTi-O ultra-low temperature denitration catalyst
Example 3: and (3) preparing the MnCeTi-O ultralow-temperature denitration catalyst with the manganese element content of 24 wt% and the cerium element content of 24 wt%.
Step 1: 6.31g of the manganese nitrate solution and 7.64g of the cerium nitrate solid were dissolved in 100g of distilled water, and stirred for 30 minutes to obtain a mixed solution.
Step 2: 3.53g of catalyst carrier titanium dioxide was added to the mixed solution of step 1, and stirring was continued for 1 hour to obtain a mixed slurry of manganese nitrate, cerium nitrate and titanium dioxide.
And 3, step 3: and (3) slowly dropping an ammonia water solution (analytically pure, with the concentration of 20-30 wt%) into the mixed slurry obtained in the step (2), adjusting the pH value of the solution to 10, and continuously stirring at normal temperature for half an hour to obtain a manganese-cerium-titanium suspension.
And 4, step 4: adopting a pneumatic stirrer with a convex or concave propeller, and arranging a vent hole on the propeller; placing the stirred manganese-cerium-titanium suspension in a pneumatic stirrer, and introducing ozone into the suspension through a vent hole while performing spiral full stirring to fully oxidize the suspension, wherein the rotating speed of a propeller is 10-15r/min, and the gas introducing amount is 300 mL/min; the color of the solution was not found to darken rapidly during oxidation, probably due to the lower aeration rate of Mn 2+ Can not be rapidly and completely oxidized into Mn 4+ Therefore, the ventilation time needs to be appropriately prolonged.
And 5: and (3) dropwise adding hydrogen peroxide into the oxidized slurry, wherein a dropper is extended into the bottom of the slurry and is dropwise added, and the dropwise adding speed is controlled to be 10 seconds per drop.
Step 6: and after continuously stirring for a period of time, centrifugally washing the slurry after the oxidation and the reduction are finished for a plurality of times to obtain a relatively wet catalyst solid.
And 7: the obtained catalyst solid is dried by a spray evaporation method (namely, the catalyst is pumped into a spray dryer and is sprayed out from the bottom of the spray dryer after being atomized by a spray head), the particle size of the introduced slurry is 10-20 mu m, the spraying temperature is controlled at 300 ℃ and 250 ℃ and the drying time is effectively reduced.
And 8: and putting the obtained dry material into a muffle furnace for temperature programming and calcining. The calcination temperature is 550 ℃, the heating rate is 10 ℃/min, and the calcination time is 4 hours.
And step 9: and (3) placing the calcined material into a ball mill for ball milling to obtain the MnCeTi-O ultralow-temperature denitration catalyst with the granularity of 1-5 mu m.
NH of MnCeTi-O ultralow temperature denitration catalyst 3 The SCR reaction activity is shown in Table 6, the denitration conversion rate of the catalyst is kept at 100% in the temperature range of 125-275 ℃, and the denitration conversion rate is always kept at more than 96% below 400 ℃, so that the catalyst has good denitration performance.
TABLE 6 characterization Activity of MnCeTi-O ultra-low temperature denitration catalyst
The XPS ion species analogy of the MnCeTi-O ultra-low temperature denitration catalyst is shown in Table 7, and comparing comparative example 1 and example 1, Mn after ozone oxidation and hydrogen peroxide reduction is known 4+ 、Ce 3+ The proportion of active oxygen species is improved, and the ventilation volume is reduced compared with the ozone ventilation volume of 500 mL/min.
TABLE 7 XPS ion species ratio of MnCeTi-O ultra-low temperature denitration catalyst
Example 4: and (3) preparing the MnCeTi-O ultralow-temperature denitration catalyst with the manganese element content of 24 wt% and the cerium element content of 24 wt%.
Step 1: 6.31g of the manganese nitrate solution and 7.64g of the cerium nitrate solid were dissolved in 100g of distilled water, and stirred for 30 minutes to obtain a mixed solution.
Step 2: 3.53g of titanium dioxide as a catalyst carrier was added to the mixed solution of step 1, and the stirring was continued for 1 hour to obtain a mixed slurry of manganese nitrate, cerium nitrate and titanium dioxide.
And step 3: and (3) slowly dropping an ammonia water solution (analytically pure, with the concentration of 20-30 wt%) into the mixed slurry obtained in the step (2), adjusting the pH value of the solution to 10, and continuously stirring at normal temperature for half an hour to obtain a manganese-cerium-titanium suspension.
And 4, step 4: adopting a pneumatic stirrer with a convex or concave propeller and arranging a vent hole on the propeller; and (3) placing the stirred manganese-cerium-titanium suspension in a pneumatic stirrer, and introducing ozone into the suspension through a vent hole while performing spiral full stirring to fully oxidize the suspension, wherein the rotating speed of a propeller is 10-15r/min, and the gas introducing amount is 500 mL/min.
And 5: and (3) dropwise adding hydrogen peroxide into the oxidized slurry, wherein a dropper is extended into the bottom of the slurry and is dropwise added, and the dropwise adding speed is controlled to be 10 seconds per drop.
Step 6: and after continuously stirring for a period of time, centrifugally washing the slurry after the oxidation and the reduction are finished for a plurality of times to obtain a relatively wet catalyst solid.
And 7: the obtained catalyst solid is dried by negative pressure (that is, a vacuum pump is used for forming a negative pressure state, and the negative pressure state is dried by a drying furnace, a heating chamber, stirring, driving, steam, filtering, condensing and other devices), and the internal temperature in the negative pressure is controlled within the range of 160-180 ℃.
And 8: and putting the obtained dry material into a muffle furnace for temperature programming and calcining. The calcination temperature is 550 ℃, the heating rate is 10 ℃/min, and the calcination time is 4 hours.
And step 9: and (3) placing the calcined material into a ball mill for ball milling to obtain the MnCeTi-O ultralow-temperature denitration catalyst with the granularity of 1-5 mu m.
NH of MnCeTi-O ultralow temperature denitration catalyst 3 The SCR reaction activity is shown in Table 8, the denitration conversion rate of the catalyst is kept at 100% in the temperature range of 125-350 ℃, and the denitration conversion rate is always kept at more than 96% below 400 ℃, so that the catalyst has good denitration performance.
TABLE 8 characterization Activity of MnCeTi-O ultra-low temperature denitration catalyst
An XPS ion species analogy of the MnCeTi-O ultra-low temperature denitration catalyst is shown in Table 9, and comparison of comparative example 1 shows that Mn is reduced by ozone oxidation and hydrogen peroxide 4+ 、Ce 3+ The proportion is improved, and low-temperature reduction is facilitated.
TABLE 9 XPS ion species ratio of MnCeTi-O ultra-low temperature denitration catalyst
Example 5: and (3) preparing the MnCeTi-O ultralow-temperature denitration catalyst with the manganese element content of 24 wt% and the cerium element content of 24 wt%.
Step 1: 6.31g of the manganese nitrate solution and 7.64g of the cerium nitrate solid were dissolved in 100g of distilled water, and stirred for 30 minutes to obtain a mixed solution.
Step 2: 3.53g of catalyst carrier titanium dioxide was added to the mixed solution of step 1, and stirring was continued for 1 hour to obtain a mixed slurry of manganese nitrate, cerium nitrate and titanium dioxide.
And step 3: and (3) slowly dropping an ammonia water solution (analytically pure, with the concentration of 20-30 wt%) into the mixed slurry obtained in the step (2), adjusting the pH value of the solution to 10, and continuously stirring at normal temperature for half an hour to obtain a manganese-cerium-titanium suspension.
And 4, step 4: adopting a pneumatic stirrer with a convex or concave propeller, and arranging a vent hole on the propeller; and (3) placing the stirred manganese-cerium-titanium suspension in a pneumatic stirrer, and introducing ozone into the suspension through a vent hole while performing spiral full stirring to fully oxidize the suspension, wherein the rotating speed of a propeller is 10-15r/min, and the gas introducing amount is 500 mL/min.
And 5: and (3) dropwise adding hydrogen peroxide into the oxidized slurry, wherein a dropper is extended into the bottom of the slurry and is dropwise added, and the dropwise adding speed is controlled to be 10 seconds per drop.
Step 6: and after continuously stirring for a period of time, centrifugally washing the slurry after the oxidation and the reduction are finished for a plurality of times to obtain a relatively wet catalyst solid.
And 7: the obtained catalyst solid is introduced into the slurry with the particle size of 10-20 mu m by adopting a spray evaporation method, the spray temperature is controlled at 250 ℃ and 300 ℃, and the drying time is effectively reduced.
And 8: and putting the obtained dry material into a muffle furnace for temperature programming and calcining. The calcining temperature is 500 ℃, the heating rate is 10 ℃/min, and the calcining time is 4 hours.
And step 9: and (3) placing the calcined material into a ball mill for ball milling to obtain the MnCeTi-O ultralow-temperature denitration catalyst with the granularity of 1-5 mu m.
NH of MnCeTi-O ultralow temperature denitration catalyst 3 The SCR reaction activity is shown in Table 10, the denitration conversion rate of the catalyst is kept at 100% in the temperature range of 125-275 ℃, and the denitration conversion rate is always kept at more than 95% below 400 ℃, so that the catalyst has good denitration performance.
TABLE 10 characterization Activity of MnCeTi-O ultra-low temperature denitration catalyst
XPS ion species ratios of MnCeTi-O ultra-low temperature denitration catalysts are shown in Table 11, and comparison of comparative example 1 and example 1 shows that Mn is reduced by ozone oxidation and hydrogen peroxide 4+ 、Ce 3+ The proportion is increased, and is reduced compared with the catalyst prepared at 550 ℃, which shows that the temperature has influence on the denitration performance of the catalyst.
TABLE 11 XPS ion species ratio of MnCeTi-O ultra-low temperature denitration catalyst
Example 6: preparing a MnLaTi-O ultralow-temperature denitration catalyst with the manganese element content of 24 wt% and the lanthanum element content of 24 wt%.
Step 1: 5.94g of the manganese nitrate solution and 7.62g of the cerium nitrate solid were dissolved in 100g of distilled water, and stirred for 30 minutes to obtain a mixed solution.
Step 2: 3.53g of catalyst carrier titanium dioxide was added to the mixed solution in step 1, and stirring was continued for 1 hour to obtain a mixed slurry of manganese nitrate, lanthanum nitrate and titanium dioxide.
And step 3: and (3) slowly dropwise adding an ammonia water solution (analytically pure, with the concentration of 20-30 wt%) into the mixed slurry obtained in the step (2), adjusting the pH value of the solution to 10, and continuously stirring at normal temperature for half an hour to obtain a manganese lanthanum titanium suspension.
And 4, step 4: adopting a pneumatic stirrer with a convex or concave propeller and arranging a vent hole on the propeller; and (3) placing the stirred manganese lanthanum titanium suspension in a pneumatic stirrer, and introducing ozone into the suspension through a vent hole while performing spiral full stirring to fully oxidize the suspension, wherein the rotating speed of a propeller is 10-15r/min, and the gas introduction amount is 500 mL/min.
And 5: and (3) dropwise adding hydrogen peroxide into the oxidized slurry, wherein a dropper is extended into the bottom of the slurry and is dropwise added, and the dropwise adding speed is controlled to be 10 seconds per drop.
Step 6: and after continuously stirring for a period of time, centrifugally washing the slurry after the oxidation and the reduction are finished for a plurality of times to obtain a relatively wet catalyst solid.
And 7: the obtained catalyst solid is dried by a spray evaporation method (i.e. the catalyst is pumped into a spray dryer and is sprayed out from the bottom of the spray dryer after being atomized by a spray head), the particle size of the introduced slurry is 10-20 mu m, the spraying temperature is controlled at 300 ℃ and 250-.
And 8: and putting the obtained dry material into a muffle furnace for temperature programming and calcining. The calcination temperature is 550 ℃, the heating rate is 10 ℃/min, and the calcination time is 4 hours.
And step 9: and (3) placing the calcined material into a ball mill for ball milling to obtain the MnLaTi-O ultralow-temperature denitration catalyst with the granularity of 1-5 mu m.
Comparative example 2
A denitration catalyst was prepared by the method of example 6, except that the ozone oxidation and hydrogen peroxide reduction steps were omitted.
NH of MnLaTi-O ultralow-temperature denitration catalyst 3 The SCR reaction activity is shown in Table 12, the denitration conversion rate of the catalyst is kept at 100% in the temperature range of 100 ℃ and 350 ℃, and the denitration conversion rate is always kept at more than 97% below 400 ℃, so that the catalyst has good denitration performance.
TABLE 12 characterization Activity of MnLaTi-O ultra-low temperature denitration catalyst
The XPS ion species analogy of the denitration catalysts prepared in comparative example 6 and comparative example 1 is shown in Table 13, and it is found that Mn is present after ozone oxidation and hydrogen peroxide reduction 4+ 、La 3+ The proportion is increased, and low-temperature reduction is facilitated.
TABLE 131 XPS ion species ratio of MnLaTi-O ultra-low temperature denitration catalyst
Example 7: preparing the MnGdTi-O ultralow-temperature denitration catalyst with the manganese element content of 24 wt% and the gadolinium element content of 24 wt%.
Step 1: 5.94g of manganese nitrate and 6.04g of gadolinium nitrate solid were dissolved in 100g of distilled water, and stirred for 30 minutes to obtain a mixed solution.
Step 2: 3.53g of catalyst carrier titanium dioxide was added to the mixed solution in step 1, and stirring was continued for 1 hour to obtain a mixed slurry of manganese nitrate, gadolinium nitrate and titanium dioxide.
And step 3: and (3) slowly dropping an ammonia water solution (analytically pure, with the concentration of 20-30 wt%) into the mixed slurry obtained in the step (2), adjusting the pH of the solution to 10, and continuously stirring at normal temperature for half an hour to obtain a manganese-gadolinium-titanium suspension.
And 4, step 4: adopting a pneumatic stirrer with a convex or concave propeller and arranging a vent hole on the propeller; and (3) placing the stirred manganese-gadolinium-titanium suspension in a pneumatic stirrer, and introducing ozone into the suspension through a vent hole while performing spiral full stirring to fully oxidize the suspension, wherein the rotating speed of a propeller is 10-15r/min, and the gas introducing amount is 500 mL/min.
And 5: and (3) dropwise adding hydrogen peroxide into the oxidized slurry, wherein a dropper is extended into the bottom of the slurry and is dropwise added, and the dropwise adding speed is controlled to be 10 seconds per drop.
Step 6: and after continuously stirring for a period of time, centrifugally washing the slurry after the oxidation and the reduction are finished for a plurality of times to obtain a relatively wet catalyst solid.
And 7: the obtained catalyst solid is dried by a spray evaporation method (namely, the catalyst is pumped into a spray dryer and is sprayed out from the bottom of the spray dryer after being atomized by a spray head), the particle size of the introduced slurry is 10-20 mu m, the spraying temperature is controlled at 300 ℃ and 250 ℃ and the drying time is effectively reduced.
And 8: and putting the obtained dry material into a muffle furnace for temperature programming and calcining. The calcination temperature is 550 ℃, the heating rate is 10 ℃/min, and the calcination time is 4 hours.
And step 9: and (3) putting the calcined material into a ball mill for ball milling to obtain the MnGdTi-O ultralow-temperature denitration catalyst with the granularity of 1-5 mu m.
Comparative example 3
A denitration catalyst was prepared by the method of example 7, except that the ozone oxidation and hydrogen peroxide reduction steps were omitted.
NH of MnGdTi-O ultralow-temperature denitration catalyst 3 The SCR reaction activity is shown in Table 14, the denitration conversion rate of the catalyst is maintained at 100% in the temperature range of 100 ℃ and 350 ℃, the denitration conversion rate is maintained at 97% at 400 ℃ or below, and the catalyst has good denitration performanceCan be used.
TABLE 14 characterization activity of MnGdTi-O ultra-low temperature denitration catalyst
The XPS ion species analogy of the denitration catalysts prepared in comparative example 6 and comparative example 1 is shown in Table 15, and it is found that Mn is present after ozone oxidation and hydrogen peroxide reduction 4+ 、Gd 3+ The proportion is increased, and low-temperature reduction is facilitated.
TABLE 15 XPS ion species ratio of MnCeTi-O ultra-low temperature denitration catalyst
The specific surface area and the pore diameter of the MGdTi-O ultra-low temperature denitration catalysts prepared in examples 1 to 7 are shown in Table 16.
TABLE 16 specific surface area and pore diameter of MGdTi-O ultra-low temperature denitration catalyst
| Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | Example 7 | |
| Specific surface area | 88 | 80 | 79 | 85 | 75 | 83 | 80 |
| Pore diameter | 11.43 | 12.2 | 10.6 | 12.32 | 12.94 | 12.14 | 12.08 |
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, but rather as the subject matter of the invention is to be construed in all aspects and as broadly as possible.
Claims (10)
1. Mn (manganese) 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow temperature denitration catalyst is characterized in that the denitration catalyst is TiO 2 The carrier is loaded with denitration active ingredients and rare earth metal element auxiliaries, and is prepared by ozone oxidation, hydrogen peroxide reduction and calcination.
2. A Mn as claimed in claim 1 4+ And Ce 3+ Enhanced Mn-M-Ti-O ultralow temperature denitrationThe preparation method of the catalyst is characterized in that the active component is transition metal element manganese; the auxiliary agent is one of rare earth metal elements of cerium, lanthanum and gadolinium.
3. A Mn as claimed in claim 1 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst is characterized in that the specific surface area of the denitration catalyst is 70-90M 2 Per g, particle size 1-5 μm, surface Mn 4+ 47-50% of surface Ce 3+ The proportion is 19-25%, the number of surface active oxygen species is 45-50%, and the average pore diameter is less than 13 nm; the temperature window of catalytic activity for denitration efficiency reaching more than 97 percent is 125-400 ℃.
4. A Mn as set forth in any one of claims 1 to 3 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst is characterized by comprising the following steps:
(1) mixing manganese nitrate solution with M (NO) 3 ) x Adding the solid into distilled water, stirring and dissolving to obtain a mixed solution; wherein M is Ce, La or Gd;
(2) making the catalyst carrier TiO 2 Adding the mixture into the mixed solution, and uniformly stirring to obtain mixed slurry;
(3) adjusting the pH value of the mixed slurry, and continuously stirring at normal temperature to obtain a suspension;
(4) introducing ozone into the suspension while stirring by using a pneumatic stirrer to fully oxidize the suspension;
(5) after the introduction is finished, adding hydrogen peroxide dropwise into the slurry after the ozone oxidation;
(6) after continuously stirring for a period of time, centrifugally washing for a plurality of times;
(7) drying the washed catalyst;
(8) carrying out temperature programming calcination on the dried product;
(9) grinding the calcined product into powder to obtain the material meeting the requirement.
5. A compound of claim 4n 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst is characterized in that the concentration of a manganese nitrate solution is 50 wt%, and the manganese nitrate solution and M (NO) are 3 ) x Distilled water, TiO 2 The mass ratio of (5.94-6.31): (6.04-7.64): 100: 3.53.
6. a Mn according to claim 4 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst is characterized in that in the step (3), ammonia water with the concentration of 20-30 wt% is adopted to adjust the pH value to 8-10.
7. A Mn according to claim 4 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow temperature denitration catalyst is characterized in that in the step (4), the specific method of ozone oxidation is as follows: adopting a pneumatic stirrer with a convex or concave propeller, arranging a vent hole on a propeller shaft, placing the suspension in the pneumatic stirrer, and introducing ozone into the suspension through the vent hole while stirring; the rotating speed of the propeller is 10-15r/min, and the ozone ventilation volume is 500 mL/min.
8. A Mn according to claim 4 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow-temperature denitration catalyst is characterized in that in the step (5), the specific method for dropwise adding hydrogen peroxide is as follows: and (4) extending a dropper into the bottom of the slurry, and dropwise adding hydrogen peroxide, wherein the dropping speed is controlled to be 10 seconds per drop.
9. A Mn according to claim 4 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow temperature denitration catalyst is characterized in that in the step (7), the drying method is negative pressure drying or spray evaporation: the negative pressure drying method is that a vacuum pump forms a negative pressure state, and the drying is carried out by a drying furnace, a heating chamber, stirring, driving, steam, filtering, condensing and other devices; the spray evaporation method is to pump the catalyst into a spray dryer, atomize the catalyst by a nozzle and spray the atomized catalyst out of the bottom of the spray dryer.
10. A Mn according to claim 4 4+ And Ce 3+ The preparation method of the enhanced Mn-M-Ti-O ultralow temperature denitration catalyst is characterized in that in the step (8), the temperature programming rate is 10 ℃/min, the calcination temperature is 500-.
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| CHENG CHEN 等: "Comparison of low-temperature catalytic activity and H2O/SO2 resistance of the Ce-Mn/TiO2 NH3-SCR catalysts prepared by the reverse co-precipitation, co-precipitation and impregnation method", APPLIED SURFACE SCIENCE, vol. 571, pages 151285 * |
| QUAN LI 等: "Effect of preferential exposure of anatase TiO2 {0 0 1} facets on the performance of Mn-Ce/TiO2 catalysts for low-temperature selective catalytic reduction of NOx with NH3", CHEMICAL ENGINEERING JOURNAL, vol. 369, pages 26 - 34 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115432742A (en) * | 2022-09-09 | 2022-12-06 | 浙江格派钴业新材料有限公司 | Preparation method of composite precursor material |
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