CN112958077B - Zirconium-doped lanthanum-manganese-based SCR denitration catalyst and preparation method thereof - Google Patents
Zirconium-doped lanthanum-manganese-based SCR denitration catalyst and preparation method thereof Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 62
- 238000002360 preparation method Methods 0.000 title claims abstract description 37
- AUFVVJFBLFWLJX-UHFFFAOYSA-N [Mn].[La] Chemical compound [Mn].[La] AUFVVJFBLFWLJX-UHFFFAOYSA-N 0.000 title claims abstract description 31
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims abstract description 33
- 238000001354 calcination Methods 0.000 claims abstract description 31
- 230000032683 aging Effects 0.000 claims abstract description 27
- 239000002243 precursor Substances 0.000 claims abstract description 9
- 239000011572 manganese Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 239000011259 mixed solution Substances 0.000 claims description 10
- 230000001105 regulatory effect Effects 0.000 claims description 9
- 230000033228 biological regulation Effects 0.000 claims description 8
- 229910052748 manganese Inorganic materials 0.000 claims description 7
- 229910052726 zirconium Inorganic materials 0.000 claims description 7
- 239000008139 complexing agent Substances 0.000 claims description 6
- 238000001704 evaporation Methods 0.000 claims description 4
- 229910052746 lanthanum Inorganic materials 0.000 claims description 4
- 150000002823 nitrates Chemical class 0.000 claims description 4
- 230000008020 evaporation Effects 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 238000005303 weighing Methods 0.000 claims description 2
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 27
- 230000000694 effects Effects 0.000 abstract description 21
- 238000012360 testing method Methods 0.000 abstract description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052717 sulfur Inorganic materials 0.000 abstract description 7
- 239000011593 sulfur Substances 0.000 abstract description 7
- 238000003980 solgel method Methods 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- 238000003786 synthesis reaction Methods 0.000 abstract 1
- 238000003756 stirring Methods 0.000 description 18
- 238000010438 heat treatment Methods 0.000 description 11
- OERNJTNJEZOPIA-UHFFFAOYSA-N zirconium nitrate Chemical compound [Zr+4].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O OERNJTNJEZOPIA-UHFFFAOYSA-N 0.000 description 10
- 239000002131 composite material Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 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 7
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 description 7
- 229960004543 anhydrous citric acid Drugs 0.000 description 6
- 239000012153 distilled water Substances 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 235000011114 ammonium hydroxide Nutrition 0.000 description 5
- 229960004106 citric acid Drugs 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 229910052720 vanadium Inorganic materials 0.000 description 5
- 150000001412 amines Chemical class 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- HBAGRTDVSXKKDO-UHFFFAOYSA-N dioxido(dioxo)manganese lanthanum(3+) Chemical class [La+3].[La+3].[O-][Mn]([O-])(=O)=O.[O-][Mn]([O-])(=O)=O.[O-][Mn]([O-])(=O)=O HBAGRTDVSXKKDO-UHFFFAOYSA-N 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 239000002808 molecular sieve Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 2
- 238000001308 synthesis method Methods 0.000 description 2
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- UOROWBGGYAMZCK-UHFFFAOYSA-N lanthanum(3+) manganese(2+) oxygen(2-) Chemical compound [O-2].[La+3].[Mn+2] UOROWBGGYAMZCK-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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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
- B01J23/32—Manganese, technetium or rhenium
- B01J23/34—Manganese
-
- 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
- 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
- B01D53/90—Injecting reactants
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- B01J35/394—
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- 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
- B01J37/02—Impregnation, coating or precipitation
- B01J37/03—Precipitation; Co-precipitation
- B01J37/036—Precipitation; Co-precipitation to form a gel or a cogel
-
- 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
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
- B01J37/086—Decomposition of an organometallic compound, a metal complex or a metal salt of a carboxylic acid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/40—Nitrogen compounds
- B01D2257/404—Nitrogen oxides other than dinitrogen oxide
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)
Abstract
The invention discloses a zirconium-doped lanthanum-manganese-based SCR denitration catalyst and a preparation method thereof, wherein the preparation method comprises the following steps: (1) preparing a precursor; (2) adjusting alkalinity; (3) preparing gel; (4) aging, calcining and forming. The catalyst is prepared by one-step synthesis through a citric acid sol-gel method, has a perovskite structure, has a wide SCR denitration activity temperature window, can keep excellent SCR denitration activity in a wide temperature window of 120-280 ℃ for the La site doped with Zr, has the removal rate of over 90 percent for the nitrogen oxide, can keep the removal rate of 100 percent for the nitrogen oxide at 140-240 ℃, can effectively improve the sulfur-resistant and water-resistant performance of the catalyst, and can keep the removal rate of over 95 percent for the nitrogen oxide under the test condition.
Description
Technical Field
The invention relates to the technical field of preparation of denitration catalysts, in particular to a zirconium-doped lanthanum manganese-based SCR denitration catalyst and a preparation method thereof.
Background
The emission of nitrogen oxides (NOx) in the atmosphere not only causes environmental problems such as haze, acid rain and photochemical smog, but also seriously threatens human health. Therefore, how to effectively realize the treatment of the NOx in the atmosphere becomes a research hotspot in the field of environmental protection nowadays.
Among the numerous denitration techniques, NH 3 SCR is the most efficient method, and the core is the choice of catalyst. At present, V is a catalyst widely used in industry 2 O 5 -WO 3 (MoO 3 )/TiO 2 However, the catalyst is only suitable for flue gas denitration of industrial kilns with high flue gas temperature, the catalyst is easy to deactivate, the service life is short, and the vanadium component in the catalyst can also cause adverse effects on the environment and human bodies. Therefore, the current research is mainly focused on developing non-vanadium-based NH 3 -an SCR catalyst. Non-vanadium based NH at home and abroad in recent years 3 Research in the field of SCR catalysts mainly includes molecular sieves and oxidesTwo types are provided. The molecular sieve catalyst generally has better medium-high temperature SCR activity, but low temperature activity and H resistance 2 O and SO 2 Poor poisoning performance and N 2 The selectivity is low. The oxide catalyst gradually develops from the earliest noble metal to the present composite oxide, and among the reported vanadium-free composite oxide catalysts, the manganese-based catalyst shows good low-temperature high activity. Among them, lanthanum-manganese perovskite-type manganese-based oxides have received much attention because of their advantages such as low cost, high catalytic activity, and strong stability, but manganese-based catalysts are very susceptible to H 2 O and SO 2 Is inactivated.
Disclosure of Invention
The invention aims to provide a zirconium-doped lanthanum-manganese-based SCR denitration catalyst and a preparation method thereof, which can solve the problem of vanadium-based NH 3 The problems of low activity and narrow temperature window of SCR catalysts, and non-vanadium-based NH 3 Susceptibility of SCR catalysts to H 2 O and SO 2 The influence of (b) to be inactivated.
In order to achieve the purpose, the invention provides a preparation method of a zirconium-doped lanthanum manganese-based SCR denitration catalyst, which comprises the following steps:
(1) preparation of the precursor
Weighing corresponding nitrates of La, Mn and Zr according to the molar ratio, mixing and dissolving the nitrates with a complexing agent to ensure that the molar ratio of the sum of the molar numbers of La, Mn and Zr in the mixed solution to the complexing agent is 1: 1.1-2.5;
(2) alkalinity regulation
Adding a pH regulator into the mixed solution prepared in the step (1), and regulating the pH value of the solution to 7.5-8.8;
(3) preparation of the gel
Evaporating the pH-adjusted solution until it is gel-like;
(4) aging, calcining and forming
The gel material is aged and calcined in two steps to obtain the product.
The beneficial effect who adopts above-mentioned scheme is: manganese nitrate, lanthanum nitrate and zirconium nitrate are complexed through a complexing agent, the pH value of a solution is adjusted through a pH regulator to improve the complexing speed, water molecules in a complex are removed through a sol-gel method, the complex forms a perovskite structure through aging and two-step calcination, and the method is suitable for denitration reaction.
Further, the ratio of the sum of the molar amount of Zr and the molar amount of La to the molar amount of Mn in step (1) is 1:1.
Further, the evaporation temperature in the step (3) is 80-95 ℃.
Further, the aging temperature in the step (4) is 110-150 ℃, and the aging time is 16-24 h.
Further, the first calcination temperature in the step (4) is 360-500 ℃, and the calcination time is 2.5-3.5 h.
Further, the second calcination temperature in the step (4) is 750-.
Further, the heating rate of the two times of calcination in the step (4) is 3-10 ℃/min.
A zirconium-doped lanthanum manganese-based SCR denitration catalyst, wherein the molar weight of Zr doping is 0.2 or 0.3.
In summary, the invention has the following advantages:
1. the doped modified component Zr has the functions of certain electronic additives and structural additives, can influence the electronic characteristics and the dispersibility of Mn in the perovskite lanthanum manganese composite oxide in the catalyst, broadens the active temperature window of the catalyst, enhances the sulfur-resistant and water-resistant performance of the catalyst, can keep excellent SCR denitration activity in a wide temperature window of 120-280 ℃ when the doping molar quantity of La-site doped Zr is about 0.2, has the nitrogen oxide removal rate of over 90 percent, and maintains the 100 percent nitrogen oxide removal rate at 140-240 ℃;
2. the sulfur resistance and the water resistance are better within 24 hours at the temperature of 200 ℃, and H exists simultaneously 2 O and SO 2 In the process, the removal rate of nitrogen oxides can still be kept above 95%, the activity loss is only about 5%, and the activity loss of the unmodified lanthanum manganate reaches about 12%;
3. the preparation method is a one-step synthesis method, the preparation process is simple, the requirement on equipment is low, the used raw materials are common chemical reagents, the sources are wide, the price is low, and the raw materials are easy to obtain, namely the method is easy for industrial production.
Drawings
FIG. 1 is an XRD pattern of La-site Zr and Al doped lanthanum manganese composite oxide catalyst;
FIG. 2 is a schematic diagram of the SCR activity of La-site Zr and Al doped La-Mn composite oxide catalyst;
FIG. 3 is a schematic diagram of sulfur resistance and water resistance of a La-site Zr and Al doped composite lanthanum-manganese oxide catalyst with a molar weight of 0.2.
Detailed Description
The principles and features of this invention are described below in conjunction with embodiments, which are included to explain the invention and not to limit the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Example 1
The embodiment provides a preparation method of a zirconium-doped lanthanum manganese-based SCR denitration catalyst, which comprises the following steps:
(1) preparation of the precursor
6.928g of lanthanum nitrate, 1.7173g of zirconium nitrate and 4.65ml of manganese nitrate solution with the mass fraction of 50 percent are taken and dissolved in 100ml of distilled water, and the mixture is stirred uniformly;
(2) alkalinity regulation
Adding 15.37g of anhydrous citric acid into the mixed solution in the step (1), stirring until the citric acid is completely mixed and dissolved, slowly adding ammonia water serving as a pH regulator, continuously stirring, and regulating the pH to be 8;
(3) preparation of the gel
Stirring the substance obtained in the step (2) in a water bath kettle at the temperature of 90 ℃ until the water is evaporated to dryness, and obtaining gel;
(4) aging, calcining and forming
Aging and drying the gel in an aging device at 120 ℃ for 24h, calcining the product at 400 ℃ for 3h at a temperature rise rate of 5 ℃/min, then heating to 800 ℃ for calcining for 3h at a temperature rise rate of 5 ℃/min to obtain a product, which is recorded as Zr 0.2 。
Example 2
The embodiment provides a preparation method of a zirconium-doped lanthanum manganese-based SCR denitration catalyst, which comprises the following steps:
(1) preparation of the precursor
6.062g of lanthanum nitrate, 2.5759g of zirconium nitrate and 4.65ml of manganese nitrate solution with the mass fraction of 50 percent are taken and dissolved in 100ml of distilled water, and the mixture is stirred uniformly;
(2) alkalinity regulation
Adding 15.37g of anhydrous citric acid into the mixed solution prepared in the step (1), stirring until the citric acid is completely mixed and dissolved, slowly adding ammonia water serving as a pH regulator, continuously stirring, and regulating the pH value of the solution to be 8;
(3) preparation of the gel
Stirring the product obtained in the step (2) in a water bath kettle at 90 ℃ until the water is evaporated to dryness, and preparing gel;
(4) aging, calcining and forming
Aging and drying the gel in an aging device at 120 ℃ for 24h, calcining the product at 400 ℃ for 3h at the heating rate of 5 ℃/min, then heating to 800 ℃ for calcining for 3h at the heating rate of 5 ℃/min to obtain a product, which is recorded as Zr 0.3 。
Example 3
The embodiment provides a preparation method of a zirconium-doped lanthanum-manganese-based SCR denitration catalyst, which comprises the following steps of:
(1) preparation of the precursor
4.330g of lanthanum nitrate, 4.2932g of zirconium nitrate and 4.65ml of manganese nitrate solution with the mass fraction of 50 percent are taken and dissolved in 100ml of distilled water, and the mixture is stirred uniformly;
(2) alkalinity regulation
Adding 15.37g of anhydrous citric acid into the mixed solution prepared in the step (1), stirring until the citric acid is completely mixed and dissolved, slowly adding ammonia water serving as a pH regulator, continuously stirring, and regulating the pH to be 8;
(3) preparation of the gel
Stirring the product obtained in the step (2) in a water bath kettle at the temperature of 90 ℃ until the water is evaporated to dryness, and preparing gel;
(4) aging, calcining and forming
Aging and drying the gel in an aging device at 120 ℃ for 24h, calcining the product at 400 ℃ for 3h at the heating rate of 5 ℃/min, then heating to 800 ℃ for calcining for 3h at the heating rate of 5 ℃/min to obtain a product, which is recorded as Zr 0.5 。
Comparative example 1
The comparative example provides a preparation method of a lanthanum-manganese-based SCR denitration catalyst, which comprises the following steps:
(1) preparation of the precursor
Dissolving 8.66g of lanthanum nitrate and 4.65ml of manganese nitrate solution with the mass fraction of 50% in 100ml of distilled water, adding 15.37g of anhydrous citric acid, and stirring until the mixture is completely mixed and dissolved;
(2) alkalinity regulation
Slowly adding ammonia water as a pH regulator into the mixed solution, continuously stirring, and regulating the pH to be 8;
(3) preparation of the gel
Stirring the product obtained in the step (2) in a water bath kettle at the temperature of 90 ℃ until the water is evaporated to dryness, and preparing gel;
(4) aging, calcining and forming
And aging and drying the gel in an aging device at 120 ℃ for 24h, calcining the product at 400 ℃ for 3h at the temperature rise rate of 5 ℃/min, then heating to 800 ℃ for calcining for 3h at the temperature rise rate of 5 ℃/min, and obtaining the product, namely LM.
Comparative example 2
The comparative example provides a preparation method of an aluminum-doped lanthanum manganese-based SCR denitration catalyst, which comprises the following steps:
(1) preparation of the precursor
6.928g of lanthanum nitrate, 1.5005g of aluminum nitrate and 4.65ml of manganese nitrate solution with the mass fraction of 50 percent are taken to be dissolved in 100ml of distilled water and are stirred uniformly;
(2) alkalinity regulation
Adding 15.37g of anhydrous citric acid into the mixed solution, stirring until the citric acid is completely mixed and dissolved, slowly adding ammonia water serving as a pH regulator, continuously stirring, and regulating the pH to be 8;
(3) preparation of the gel
Stirring the product obtained in the step (2) in a water bath kettle at the temperature of 90 ℃ until the water is evaporated to dryness, and preparing gel;
(4) aging, calcining and forming
Aging and drying the gel in an aging device at 120 ℃ for 24h, calcining the product at 400 ℃ for 3h at a temperature rise rate of 5 ℃/min, then heating to 800 ℃ for calcining for 3h at a temperature rise rate of 5 ℃/min to obtain a product, and marking the product as Al 0.2 。
Comparative example 3
The comparative example provides a preparation method of a lanthanum manganese-based SCR denitration catalyst regulated by zirconium-doped organic amine, which comprises the following steps:
(1) preparation of the precursor
6.928g of lanthanum nitrate, 1.7173g of zirconium nitrate and 4.65ml of manganese nitrate solution with the mass fraction of 50 percent are dissolved in 100ml of distilled water and are uniformly mixed;
(2) alkalinity regulation
Adding 15.37g of anhydrous citric acid into the mixed solution, stirring until the citric acid is completely mixed and dissolved, slowly adding triethanolamine serving as a pH regulator, continuously stirring, and regulating the pH to be 8;
(3) preparation of the gel
Stirring the product obtained in the step (2) in a water bath kettle at the temperature of 90 ℃ to evaporate water to prepare gel;
(4) aging, calcining and forming
Aging and drying the gel in an aging device at 120 ℃ for 24h, calcining the product at 400 ℃ for 3h at a temperature rise rate of 5 ℃/min, then heating to 800 ℃ for calcining for 3h at a temperature rise rate of 5 ℃/min to obtain a product, which is recorded as Zr 0.2 -an organic amine.
Zr removal from the above product 0.5 Except the lanthanum-manganese composite oxide with a perovskite structure can be used as a low-temperature SCR denitration catalyst. XRD tests are carried out on the products prepared in each example and comparative example, the test results are collectively drawn as figure 1, the denitration activity curve is collectively drawn as figure 2, and the resistance curve is collectively drawn as figure 3. Wherein, the XRD pattern scanning angle of the product is 10-80 degrees, and a fixed bed device is used for testing the SCR denitration activity and resistance of the product. Fixed bed deviceThe inner diameter of the reaction tube is 14mm, and the test conditions are as follows: NO 500ppm, NH 3 ＝500ppm，O 2 ＝5％，N 2 As balance gas, the total gas amount is 500mL/min, and the space velocity is 30000h -1 . The gas components are analyzed by a Gasbard-3000 flue gas analyzer of Wuhan tetragonal photoelectric technology Limited. The conversion was calculated using the following formula:
wherein [ NOx ] in is the concentration of NOx at the inlet of the flue gas analyzer, and [ NOx ] out is the concentration of NOx at the outlet of the flue gas analyzer.
The test results are shown in fig. 2 and 3, respectively.
As can be seen from FIG. 1, La-Mn composite oxide LaMnO having perovskite structure at 2 θ of about 22.9 °, 32.6 °, 40.2 °, 46.8 °, 52.7 °, 58.2 °, 68.3 °, 73.1 ° and 77.8 ° all 3 Diffraction peaks of (a) respectively corresponding to LaMnO 3 The crystal planes (100), (110), (111), (200), (210), (211), (220), (300) and (310) show that the prepared sample has a cubic structure, and XRD after Al doping also shows diffraction peaks of the crystal planes, which shows that LaMnO is not destroyed after doping modification 3 The cubic structure of (a). When the Zr doping molar quantity is 0.2 and 0.3, diffraction peaks of the crystal face appear by XRD, which shows that LaMnO is not destroyed when the doping quantity is less 3 And at the same time, a diffraction peak of the Mn oxide appears. When the molar amount of Zr doping reaches 0.5, the molecular weight is assigned to LaMnO 3 The diffraction peak of (a) is reduced or disappeared, indicating that when the doping amount is too large, the perovskite structure is destroyed. Therefore, the preferred Zr doping molar amount of the invention is 0.2 and 0.3.
As can be seen from FIG. 2, the temperature test range is 80 to 300 ℃, and the comparison shows that the denitration activity in the low temperature range is better than that of LaMnO when the molar weight of Al doped is 0.2, and the molar weight of Zr doped is 0.2, 0.3 and 0.5 3 When the pH regulator is organic amine and the Zr doping molar weight is 0.2, the denitration activity of the catalyst is obviously reduced, which indicates that the pH regulator is not suitable for selecting organic amine.
From FIG. 3, it can be seen thatThe test temperature is 200 ℃, and H is introduced 2 O content 10 vol%, SO 2 Is 100 ppm. The comparison shows that the sulfur resistance and the water resistance of the catalyst after doping modification are improved, wherein the improvement effect of Zr is obvious. When 10 vol% H is introduced 2 After O, the removal rate of the three catalysts is not reduced, which shows that the catalysts have good water resistance, and when H exists at the same time 2 O and SO 2 In the case of the catalyst, the resistance of the Zr modified catalyst is best, the nitrogen oxide removal rate can be kept to be more than 95%, and when the SO is stopped to be introduced 2 The post-activity energy is recovered to about 97 percent of the original data, and the introduction of H is stopped 2 After O, the activity is kept about 97% of the original data, indicating that H 2 O and SO 2 The inhibition of the catalyst is essentially reversible.
In summary, according to the preparation method of the zirconium-doped lanthanum manganese-based SCR denitration catalyst provided by the invention, the doped modification component Zr has certain functions of an electronic assistant and a structural assistant, can influence the electronic characteristics and the dispersibility of Mn in the perovskite lanthanum manganese composite oxide in the catalyst, broadens the active temperature window of the catalyst, enhances the sulfur-resistant and water-resistant performance of the catalyst, can keep excellent SCR denitration activity in a wide temperature window of 120-280 ℃ when the doping molar amount of Zr is about 0.2, has the nitrogen oxide removal rate of more than 90%, maintains the 100% nitrogen oxide removal rate at 140-240 ℃, has better sulfur-resistant and water-resistant performance within 24 hours at 200 ℃, and has H 2 O and SO 2 In the process, the removal rate of nitrogen oxides can still be kept above 95%, the activity loss is only about 5%, and the activity loss of lanthanum manganate before being modified reaches about 12%.
The preparation method of the zirconium-doped lanthanum manganese-based SCR denitration catalyst provided by the invention is a one-step synthesis method, the preparation process is simple, the requirement on equipment is lower, the used raw materials are common chemical reagents, the source is wide, the price is low, and the catalyst is easy to obtain, namely the catalyst is easy for industrial production.
While the present invention has been described in detail with reference to the illustrated embodiments, it should not be construed as limited to the scope of the present patent. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.
Claims (8)
1. A preparation method of a zirconium-doped lanthanum manganese-based SCR denitration catalyst is characterized by comprising the following steps of:
(1) preparation of the precursor
Weighing corresponding nitrates of La, Mn and Zr according to the molar ratio, mixing and dissolving the nitrates with a complexing agent to ensure that the molar ratio of the sum of the molar numbers of La, Mn and Zr in the mixed solution to the complexing agent is 1: 1.1-2.5;
wherein the ratio of the sum of the molar amount of Zr and the molar amount of La to the molar amount of Mn is 1: 1;
(2) alkalinity regulation
Adding a pH regulator into the mixed solution prepared in the step (1), and regulating the pH value of the solution to 7.5-8.8;
(3) preparation of the gel
Evaporating the pH-adjusted solution until it is gel-like;
(4) aging, calcining and forming
Aging and calcining the gel material in two steps to prepare a perovskite type zirconium-doped lanthanum manganese-based SCR denitration catalyst;
in the perovskite type zirconium-doped lanthanum manganese-based SCR denitration catalyst, the molar weight of Zr doping is 0.2 or 0.3.
2. The method for preparing the zirconium-doped lanthanum manganese-based SCR denitration catalyst as recited in claim 1, wherein the complexing agent in the step (1) is citric acid.
3. The method for preparing the zirconium-doped lanthanum manganese-based SCR denitration catalyst according to claim 1, wherein the evaporation temperature in the step (3) is 80-95 ℃.
4. The method for preparing the zirconium-doped lanthanum manganese-based SCR denitration catalyst as recited in claim 1, wherein the aging temperature in the step (4) is 110-150 ℃, and the aging time is 16-24 h.
5. The method for preparing the zirconium-doped lanthanum-manganese-based SCR denitration catalyst as recited in claim 1, wherein the first calcination temperature in the step (4) is 360-500 ℃, and the calcination time is 2.5-3.5 h.
6. The method for preparing the zirconium-doped lanthanum manganese-based SCR denitration catalyst as recited in claim 1, wherein the second calcination temperature in the step (4) is 750-.
7. The method for preparing the zirconium-doped lanthanum manganese-based SCR denitration catalyst as recited in claim 1, wherein the temperature rise rate of the two calcinations in the step (4) is 3-10 ℃/min.
8. The zirconium-doped lanthanum-manganese-based SCR denitration catalyst is prepared by the preparation method of the zirconium-doped lanthanum-manganese-based SCR denitration catalyst according to any one of claims 1 to 7.
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