CN111701610A - Vanadium-substituted heteropoly acid SCR catalyst and preparation method thereof - Google Patents
Vanadium-substituted heteropoly acid SCR catalyst and preparation method thereof Download PDFInfo
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- 239000011964 heteropoly acid Substances 0.000 title claims abstract description 77
- 239000003054 catalyst Substances 0.000 title claims abstract description 65
- 238000002360 preparation method Methods 0.000 title abstract description 12
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 16
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000000605 extraction Methods 0.000 claims abstract description 12
- 229910001868 water Inorganic materials 0.000 claims abstract description 11
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 5
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 5
- 238000005470 impregnation Methods 0.000 claims abstract description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 34
- 238000006243 chemical reaction Methods 0.000 claims description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 238000003756 stirring Methods 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 15
- 238000001035 drying Methods 0.000 claims description 11
- 229910052755 nonmetal Inorganic materials 0.000 claims description 10
- 239000002002 slurry Substances 0.000 claims description 10
- 239000000376 reactant Substances 0.000 claims description 9
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 9
- 238000001291 vacuum drying Methods 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 8
- LSGOVYNHVSXFFJ-UHFFFAOYSA-N vanadate(3-) Chemical compound [O-][V]([O-])([O-])=O LSGOVYNHVSXFFJ-UHFFFAOYSA-N 0.000 claims description 8
- 238000006467 substitution reaction Methods 0.000 claims description 7
- 125000004429 atom Chemical group 0.000 claims description 6
- 150000001875 compounds Chemical class 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- 238000011068 loading method Methods 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- 125000005842 heteroatom Chemical group 0.000 claims description 3
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 claims description 2
- 239000002253 acid Substances 0.000 claims description 2
- DHRLEVQXOMLTIM-UHFFFAOYSA-N phosphoric acid;trioxomolybdenum Chemical compound O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.O=[Mo](=O)=O.OP(O)(O)=O DHRLEVQXOMLTIM-UHFFFAOYSA-N 0.000 claims description 2
- IYDGMDWEHDFVQI-UHFFFAOYSA-N phosphoric acid;trioxotungsten Chemical compound O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.OP(O)(O)=O IYDGMDWEHDFVQI-UHFFFAOYSA-N 0.000 claims description 2
- CGFYHILWFSGVJS-UHFFFAOYSA-N silicic acid;trioxotungsten Chemical compound O[Si](O)(O)O.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 CGFYHILWFSGVJS-UHFFFAOYSA-N 0.000 claims description 2
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 30
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 11
- 239000002131 composite material Substances 0.000 abstract description 11
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 abstract description 4
- 239000011593 sulfur Substances 0.000 abstract description 4
- 229910052717 sulfur Inorganic materials 0.000 abstract description 4
- 239000004566 building material Substances 0.000 abstract description 3
- 230000002195 synergetic effect Effects 0.000 abstract description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 abstract description 3
- 239000010937 tungsten Substances 0.000 abstract description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract 1
- 239000011574 phosphorus Substances 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 12
- 239000008367 deionised water Substances 0.000 description 7
- 229910021641 deionized water Inorganic materials 0.000 description 7
- 238000011161 development Methods 0.000 description 5
- 229910019501 NaVO3 Inorganic materials 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- -1 ether compound Chemical class 0.000 description 4
- 239000012495 reaction gas Substances 0.000 description 4
- 238000003915 air pollution Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000013074 reference sample Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 229910020350 Na2WO4 Inorganic materials 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- XMVONEAAOPAGAO-UHFFFAOYSA-N sodium tungstate Chemical compound [Na+].[Na+].[O-][W]([O-])(=O)=O XMVONEAAOPAGAO-UHFFFAOYSA-N 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- ODUCDPQEXGNKDN-UHFFFAOYSA-N Nitrogen oxide(NO) Natural products O=N ODUCDPQEXGNKDN-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000809 air pollutant Substances 0.000 description 1
- 231100001243 air pollutant Toxicity 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 125000004437 phosphorous atom Chemical group 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000004083 survival effect Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- PBYZMCDFOULPGH-UHFFFAOYSA-N tungstate Chemical compound [O-][W]([O-])(=O)=O PBYZMCDFOULPGH-UHFFFAOYSA-N 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
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/14—Phosphorus; Compounds thereof
- B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J27/195—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with vanadium, niobium or tantalum
- B01J27/198—Vanadium
- B01J27/199—Vanadium with chromium, molybdenum, tungsten or polonium
-
- 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
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
- B01D53/9413—Processes characterised by a specific catalyst
- B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
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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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/009—Preparation by separation, e.g. by filtration, decantation, screening
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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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0201—Impregnation
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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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Abstract
The invention discloses a vanadium-substituted phosphotungstic heteropoly acid catalyst and a preparation method thereof, belonging to the technical field of atmospheric pollution control. The composite oxide catalyst is prepared by an ether extraction method and an impregnation method, and is characterized in that the synergistic effect among three components of phosphorus, tungsten and vanadium ensures that the composite oxide catalyst has good denitration performance. The composite oxide catalyst prepared by the invention has the nitrogen oxide removal efficiency of over 90 percent in the temperature range of 300-450 ℃, has good nitrogen selectivity and water and sulfur resistance, can be used for removing nitrogen oxide discharged from fixed sources such as coal-fired power plants, industrial boilers, building material furnaces and the like and mobile sources of diesel vehicles, and has good application prospect.
Description
Technical Field
The invention relates to an SCR catalyst and a preparation method thereof, in particular to a heteropoly acid SCR catalyst and a preparation method thereof, belonging to the technical field of preparation of catalytic materials and the technical field of air pollution control.
Background
Atmospheric environmental protection is related to human survival and development, currently, the situation of atmospheric pollution in major industrially developed countries in the world is severe, regional atmospheric environmental problems are increasingly prominent, particularly, opportunities for industrial revolution are missed in the economic development process of third world countries, the situation of changing pollution into economic development is still difficult to get rid of in the current economic process, but most developing countries have realized that the traditional industrial development path is difficult to continue, and the atmospheric control strategy advocated by the countries is developed, so that remarkable effects are achieved. Wherein, in 6 months in 2013, the air pollution control action plan of China firstly mentions the new height of the air pollution control as one of the main air pollutants, namely Nitrogen Oxide (NO)x) Emission standards are also becoming more stringent. Most of the compounds have toxicity, can induce acid rain to cause ozone holes, have serious damage effect on the environment and cause great harm to human health. Emission control has become a research focus in the field of environmental catalysis and atmospheric control. Selective catalytic reduction of nitrogen oxides NH by ammonia gas3SCR is the most widely used technology for removing nitrogen oxides at present, and a high-efficiency and stable catalyst is the key of the SCR technology.
Currently, the industrial application of the mature NH is3The SCR catalyst is a V-based catalyst which, although having good SCR catalytic activity, has some unavoidable disadvantages, such as V2O5Has the advantages of biological toxicity, narrow active temperature window and N at high temperature2Poor selectivity, etc., which greatly limits their further industrial applications. Therefore, development of a compound having better N2The novel environment-friendly SCR catalyst with selectivity and wide temperature window becomes a technical problem to be solved urgently.
Disclosure of Invention
In order to solve the problems of the prior art, the invention aims to overcome the defects in the prior art and provide the vanadium-substituted heteropoly acid SCR catalyst and the preparation method thereof.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
a vanadium-substituted heteropoly acid SCR catalyst with chemical formula of ER12-xVx/TiO2Wherein the non-metal element E is P or Si, the metal element R is W or Mo, and TiO2The mass fraction of the heteropoly acid in the catalyst is 10-30 wt.%, x represents the substitution number of vanadium atoms, the value of x is not more than 3, and the vanadium atoms are used for substituting heteroatoms in heteropoly acid molecules, so that the vanadium-substituted heteropoly acid compound has SCR activity.
As a preferred technical scheme of the invention, the heteropoly acid molecules substituted by vanadium atoms are phosphotungstic acid, phosphomolybdic acid, silicotungstic acid or silicomolybdic acid molecules.
As a preferred technical scheme of the invention, the mass fraction of the heteropoly acid in the catalyst is 15-30 wt.%. More preferably, the mass fraction of heteropolyacid is 15 wt.%.
As a preferable technical scheme of the invention, the heteropoly acid is phosphotungstic heteropoly acid, and the compound molecule of the heteropoly acid is PW12-xVx/TiO2The mass fraction of the heteropoly acid in the catalyst is 10-30 wt.%, x represents the substitution number of vanadium atoms, and the value of x is (1-3). More preferably, the substitution number of the vanadium atom is 1, i.e., x is 1.
The invention relates to a preparation method of a vanadium-substituted heteropoly acid SCR catalyst, which comprises the following steps:
a. dissolving a metalate and a non-metalate which have a molar ratio of metal atoms to non-metal atoms of 10:1 as reactants in water, fully mixing, and reacting at 80-100 ℃ for at least 30 minutes, wherein the non-metal element in the non-metalate is P or Si, and the metal element in the metalate is W or Mo; preferably, tungstate and phosphate with the molar concentration ratio of tungsten atoms to phosphorus atoms of 10:1 are taken as reactants and dissolved in water for fully mixing;
b. dissolving vanadate in water to obtain a vanadate solution, wherein the molar ratio of vanadium atoms to non-metal atoms in the step a is 2x:1, adding the vanadate solution into the product solution in the step a, and continuing to react for at least 30 minutes, wherein the value of x is (0.5-1.5);
c. adding a proper amount of dilute sulfuric acid with the mass percentage concentration not higher than 50 wt.% into the product solution in the step b, adjusting the pH of the solution to be 1.8-3.0, and continuing the reaction for at least 1 hour;
d. transferring the product solution reacted in the step c to a separating funnel, continuously dropwise adding 50 wt.% dilute sulfuric acid in the extraction process by adopting an ether extraction method, taking down the oily substance in the lower layer after extraction, removing ether, recrystallizing and drying to obtain vanadium-substituted heteropoly acid;
e. loading the vanadium-substituted heteropoly acid prepared in the step d in anatase TiO by adopting an impregnation method2Wherein the mass fraction of the heteropoly acid is heteropoly acid and anatase TiO210-30 wt.% of the total mass, stirring the heteropolyacid and anatase TiO at room temperature2For 2-5 hours to obtain a slurry-like mixture;
f. naturally drying the slurry mixture obtained in the step e, or drying the slurry mixture in a vacuum drying oven at 60-90 ℃ for 6-12 hours, and then roasting the slurry mixture at 400-500 ℃ for 2-4 hours to obtain the vanadium-substituted heteropoly acid SCR catalyst.
As a preferred technical scheme of the invention, in the step a, the reaction temperature is 90-100 ℃. More preferably, the reaction temperature is 90 ℃.
As a preferred embodiment of the present invention, in step b, the atomic ratio of vanadium to nonmetal is 2:1, i.e., x is 1.
As a preferable embodiment of the present invention, in step c, the pH of the solution is adjusted to 2.0 to 3.0, and the reaction is continued. More preferably, the pH is 2.
As a preferred technical solution of the present invention, in step e, the mass fraction of the heteropoly acid is 15-30 wt.%, and the stirring time is at least 3 hours. More preferably, the mass fraction of heteropolyacid is 15 wt.%, and the stirring time is 3-5 hours.
As a preferred technical scheme of the invention, in the step f, drying is carried out for 8-12 hours in a vacuum drying oven at 70-90 ℃, the roasting temperature is 450-500 ℃, and the roasting time is 4 hours. More preferably, the mass fraction of heteropolyacid is 15 wt.%, and the stirring time is 3 hours.
Further, the method comprises the following steps: putting a proper amount of the obtained catalyst into a continuous flow fixed bed reactor, wherein the reaction gas in the fixed bed reactor comprises 0.05 percent of NO and 0.05 percent of NH in percentage by mass3And 5% of O2By using N2As balance gas, the flow rate of the reaction gas is 300mL/min, and the space velocity is 90000cm3/(g.h), about 45500h-1The activity evaluation temperature range was 200-450 ℃, and the catalysts were then tested for nitrogen oxide conversion and nitrogen selectivity ratio.
Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:
1. according to the invention, vanadium atoms are adopted to substitute heteroatoms in heteropoly acid molecules to endow the heteropoly acid molecules with good oxidation-reduction performance, so that the heteropoly acid molecules can be used for SCR reaction; the titanium dioxide mainly exists in the form of anatase titanium dioxide which is beneficial to denitration reaction; meanwhile, the transfer of electrons among active components is promoted by the synergistic catalytic action of vanadium, tungsten and titanium, the oxygen content on the surface of the catalyst is increased, the adsorption and activation of reactant molecules are promoted, the denitration performance of the catalyst is effectively improved, the active temperature window of the catalyst is widened, and the denitration efficiency is good;
2. the net conversion rate of the nitrogen oxide of the composite catalyst is more than 90% in the temperature range of 300-450 ℃, and compared with a comparison sample, the activity data is greatly improved;
3. the composite catalyst can be used for removing nitrogen oxides discharged by fixed sources such as coal-fired power plants, industrial boilers, building material furnaces and the like and mobile sources of diesel vehicles.
Drawings
FIG. 1 is a graph comparing the nitrogen oxide conversion of example one of the present invention with that of a comparative example.
FIG. 2 is a graph comparing nitrogen selectivity in example one of the present invention and comparative example.
FIG. 3 is a graph showing the results of the water-resistant and sulfur-resistant performance tests of the catalysts of the examples of the present invention.
Detailed Description
The above-described scheme is further illustrated below with reference to specific embodiments, which are detailed below:
the first embodiment is as follows:
in this embodiment, a method for preparing a vanadium-substituted heteropoly acid SCR catalyst includes the following steps:
a. respectively taking 0.03mol of Na2WO4·2H2O and 0.003mol NaHPO4Dissolving the reactants in 60mL of water, stirring the reactants uniformly, fully mixing the reactants, and reacting the reactants for 30 minutes at 90 ℃;
b. 0.006mol NaVO is taken3Dissolving in 15mL deionized water to obtain vanadate solution, and magnetically stirring for 30min until the solution becomes clear to obtain NaVO3A solution; b, when the reaction in the step a is finished, adding the prepared NaVO3Pouring the solution into the product solution prepared in the step a, and continuously reacting for 30 min;
c. after the reaction in the step b is finished, adding a proper amount of dilute sulfuric acid with the concentration of 50 wt.% into the product solution, adjusting the pH of the solution to 2.0, and continuing stirring for 1 hour until the solution is cooled to room temperature;
d. transferring the product solution reacted in the step c to a separating funnel, adopting an ether extraction method, pouring a proper amount of ether in the extraction process, continuously dropwise adding a dilute sulfuric acid solution with the concentration of 50 wt.%, fully oscillating, standing, dividing the solution into three layers, taking the yellow oily ether compound at the lower layer, introducing air into the yellow oily ether compound to blow off the ether, adding deionized water to recrystallize, and finally, carrying out vacuum drying for 8 hours to obtain the vanadium-substituted heteropoly acid;
e. using an immersion method, 0.353g of the vanadium-substituted heteropolyacid obtained in step d is dissolved in a small amount of deionized water, and 2g of anatase TiO is added thereto2Equivalent to 15 wt.% mass fraction of heteropoly acid; stirring the heteropolyacid and anatase TiO at room temperature2For 4 hours to obtain a slurry-like mixture, thereby loading heteropoly acid molecules on anatase TiO2The above step (1);
f. and (e) drying the slurry mixture obtained in the step e in a vacuum drying oven at 70 ℃ for 8 hours, and then roasting at 450 ℃ for 4 hours to obtain the vanadium-substituted heteropoly acid SCR catalyst.
Comparative example one:
in this comparative example, PW12/TiO2The preparation method of the composite reference oxide catalyst comprises the following steps:
(1) 0.353g of commercial phosphotungstic heteropoly acid was dissolved in a small amount of deionized water, to which anatase TiO was added2Wherein the mass fraction of the heteropoly acid is 15 percent, the catalyst is kept to be slurry, and the stirring is carried out for 3 hours;
(2) after stirring, drying the slurry mixture obtained in the step (1) in a vacuum drying oven at 70 ℃ for 8 hours;
(3) finally roasting the mixture for 4 hours at 450 ℃ in a muffle furnace to obtain PW12/TiO2A composite oxide catalyst.
This comparative example prepared PW12/TiO2The composite oxide catalyst was used as a reference sample.
Comparative example two:
in this comparative example, pure PW11V1The preparation method of the catalyst comprises the following steps:
taking a small amount of PW prepared in example one11V1Roasting the heteropoly acid in a muffle furnace for 4 hours at 450 ℃ to obtain PW11V1A catalyst.
This comparative example prepared PW11V1Catalyst, as reference sample, ready for use.
Comparative example three:
in this comparative example, pure TiO2The preparation method of the catalyst comprises the following steps:
taking a small amount of commercial anatase TiO2Roasting in a muffle furnace for 4 hours at 450 ℃ to obtain TiO2A catalyst.
This comparative example prepared TiO2Catalyst, as reference sample, ready for use.
Experimental test analysis and comparison:
experimental test analysis of the catalytic performance of the first example and the comparative example are compared as follows:
0.2g of catalyst was placed in a continuous flow fixed bed reactor, and the reaction gas had a composition of 0.05% NO and 0.05% NH, by mass3，5％O2Nitrogen is used as balance gas, the flow rate of reaction gas is 300mL/min, and the space velocity is 90000cm3/(g.h), about 45500h-1The activity evaluation temperature range is 200-450 ℃. At different temperatures, the catalyst reduces NOxThe conversion rate and the nitrogen selectivity are shown in fig. 1 and fig. 2, and it can be seen that compared with commercial unmodified phosphotungstic heteropoly acid, the denitration activity of the catalyst prepared by the invention is obviously improved, and the catalyst has good water-resistant and sulfur-resistant performance as shown in fig. 3.
Example two:
this embodiment is substantially the same as the first embodiment, and is characterized in that:
in this embodiment, a method for preparing a vanadium-substituted heteropoly acid SCR catalyst includes the following steps:
a. respectively taking 0.03mol of Na2WO4·2H2O and 0.003mol NaHPO4Dissolving the reactants in 60mL of water, stirring uniformly, fully mixing, and then reacting for 30 minutes at 100 ℃;
b. 0.006mol NaVO is taken3Dissolving in 15mL deionized water to obtain vanadate solution, and magnetically stirring for 30min until the solution becomes clear to obtain NaVO3A solution; b, when the reaction in the step a is finished, adding the prepared NaVO3Pouring the solution into the product solution prepared in the step a, and continuously reacting for 30 min;
c. after the reaction in the step b is finished, adding a proper amount of dilute sulfuric acid with the concentration of 50 wt.% into the product solution, adjusting the pH of the solution to 3.0, and continuing stirring for 1 hour until the solution is cooled to room temperature;
d. transferring the product solution reacted in the step c to a separating funnel, adopting an ether extraction method, pouring a proper amount of ether in the extraction process, continuously dropwise adding a dilute sulfuric acid solution with the concentration of 50 wt.%, fully oscillating, standing, dividing the solution into three layers, taking the yellow oily ether compound at the lower layer, introducing air into the yellow oily ether compound to blow off the ether, adding deionized water to recrystallize, and finally, carrying out vacuum drying for 8 hours to obtain the vanadium-substituted heteropoly acid;
e. using a dipping method, 0.857g of the vanadium-substituted heteropoly acid prepared in the step d is dissolved in a small amount of deionized water, and 2g of anatase TiO is added thereto2Equivalent to 30 wt.% of heteropolyacid; stirring the heteropolyacid and anatase TiO at room temperature2For 5 hours to obtain a slurry-like mixture, thereby loading heteropoly acid molecules on anatase TiO2The above step (1);
f. and e, drying the slurry mixture obtained in the step e in a vacuum drying oven at 90 ℃ for 12 hours, and then roasting at 500 ℃ for 4 hours to obtain the vanadium-substituted heteropoly acid SCR catalyst.
The novel vanadium-substituted phosphotungstic heteropoly acid catalyst is prepared by the embodiment, and the composite oxide catalyst is prepared by an ether extraction method and an impregnation method, and is characterized in that the synergistic effect among three components of phosphotungstic heteropoly acid catalyst and phosphotungstic heteropoly acid catalyst enables the composite oxide catalyst to have good denitration performance. The composite oxide catalyst prepared by the embodiment has the nitrogen oxide removal efficiency of over 90 percent in the temperature range of 300-450 ℃, has good nitrogen selectivity and water and sulfur resistance, can be used for removing nitrogen oxides discharged from fixed sources such as coal-fired power plants, industrial boilers, building material furnaces and the like and mobile sources of diesel vehicles, and has good application prospect.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitution ways, as long as the purpose of the present invention is met, and the invention shall fall within the protection scope of the present invention as long as the technical principle and inventive concept of the vanadium-substituted heteropoly acid SCR catalyst and the preparation method thereof of the present invention are not departed.
Claims (10)
1. Vanadium-substituted heteropoly acid SCR catalystCharacterized in that it has the chemical formula ER12-xVx/TiO2Wherein the non-metal element E is P or Si, the metal element R is W or Mo, and TiO2The mass fraction of the heteropoly acid in the catalyst is 10-30 wt.%, x represents the substitution number of vanadium atoms, the value of x is not more than 3, and the vanadium atoms are used for substituting heteroatoms in heteropoly acid molecules, so that the vanadium-substituted heteropoly acid compound has SCR activity.
2. The vanadium-substituted heteropoly acid SCR catalyst of claim 1, wherein: the heteropoly acid molecules substituted by vanadium atoms are phosphotungstic acid, phosphomolybdic acid, silicotungstic acid or silicomolybdic acid molecules.
3. The vanadium-substituted heteropoly acid SCR catalyst of claim 1, wherein: the mass fraction of heteropolyacid in the catalyst is 15-30 wt.%.
4. The vanadium-substituted heteropolyacid SCR catalyst according to any one of claims 1 to 3, characterized in that: the heteropoly acid is phosphotungstic heteropoly acid, and the compound molecule of the heteropoly acid is PW12-xVx/TiO2The mass fraction of the heteropoly acid in the catalyst is 10-30 wt.%, x represents the substitution number of vanadium atoms, and the value of x is (1-3).
5. A method for preparing the vanadium-substituted heteropoly acid SCR catalyst according to claim 1, comprising the steps of:
a. dissolving a metalate and a non-metalate which have a molar ratio of metal atoms to non-metal atoms of 10:1 as reactants in water, fully mixing, and reacting at 80-100 ℃ for at least 30 minutes, wherein the non-metal element in the non-metalate is P or Si, and the metal element in the metalate is W or Mo;
b. dissolving vanadate in water to obtain a vanadate solution, wherein the molar ratio of vanadium atoms to non-metal atoms in the step a is 2x:1, adding the vanadate solution into the product solution in the step a, and continuing to react for at least 30 minutes, wherein the value of x is (0.5-1.5);
c. adding a proper amount of dilute sulfuric acid with the mass percentage concentration not higher than 50 wt.% into the product solution in the step b, adjusting the pH of the solution to be 1.8-3.0, and continuing the reaction for at least 1 hour;
d. transferring the product solution reacted in the step c to a separating funnel, continuously dropwise adding 50 wt.% dilute sulfuric acid in the extraction process by adopting an ether extraction method, taking down the oily substance in the lower layer after extraction, removing ether, recrystallizing and drying to obtain vanadium-substituted heteropoly acid;
e. loading the vanadium-substituted heteropoly acid prepared in the step d in anatase TiO by adopting an impregnation method2Wherein the mass fraction of the heteropoly acid is heteropoly acid and anatase TiO210-30 wt.% of the total mass, stirring the heteropolyacid and anatase TiO at room temperature2For 2-5 hours to obtain a slurry-like mixture;
f. naturally drying the slurry mixture obtained in the step e, or drying the slurry mixture in a vacuum drying oven at 60-90 ℃ for 6-12 hours, and then roasting the slurry mixture at 400-500 ℃ for 2-4 hours to obtain the vanadium-substituted heteropoly acid SCR catalyst.
6. The method for preparing the vanadium-substituted heteropoly acid SCR catalyst according to claim 5, wherein: in the step a, the reaction temperature is 90-100 ℃.
7. The method for preparing the vanadium-substituted heteropoly acid SCR catalyst according to claim 5, wherein: in said step b, the vanadium to non-metal atomic ratio is 2:1, i.e. x ═ 1.
8. The method for preparing the vanadium-substituted heteropoly acid SCR catalyst according to claim 5, wherein: in the step c, the pH of the solution is adjusted to 2.0-3.0, and the reaction is continued.
9. The method for preparing the vanadium-substituted heteropoly acid SCR catalyst according to claim 5, wherein: in the step e, the mass fraction of the heteropoly acid is 15-30 wt.%, and the stirring time is 3-5 hours.
10. The method for preparing the vanadium-substituted heteropoly acid SCR catalyst according to claim 5, wherein: in the step f, drying for 8-12 hours at 70-90 ℃ in a vacuum drying oven, wherein the roasting temperature is 450-500 ℃ and the roasting time is 4 hours.
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| CN113058647A (en) * | 2021-03-26 | 2021-07-02 | 福州大学 | Iron-substituted heteropoly acid-loaded polyphenylene sulfide denitration sulfur-resistant composite filter material |
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| CN104888795A (en) * | 2015-05-29 | 2015-09-09 | 上海大学 | Titanium oxide loaded vanadate denitration catalyst as well as preparation method and application thereof |
| CN109603871A (en) * | 2018-11-26 | 2019-04-12 | 清华大学盐城环境工程技术研发中心 | It is a kind of using phosphorus tungsten vanadium heteropoly acid as denitrating catalyst of presoma and preparation method thereof |
| CN109794272A (en) * | 2019-01-25 | 2019-05-24 | 安徽工业大学 | A kind of support type phosphato-molybdic heteropolyacid low-temperature SCR catalyst and preparation method thereof |
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| CN104888795A (en) * | 2015-05-29 | 2015-09-09 | 上海大学 | Titanium oxide loaded vanadate denitration catalyst as well as preparation method and application thereof |
| CN109603871A (en) * | 2018-11-26 | 2019-04-12 | 清华大学盐城环境工程技术研发中心 | It is a kind of using phosphorus tungsten vanadium heteropoly acid as denitrating catalyst of presoma and preparation method thereof |
| CN109794272A (en) * | 2019-01-25 | 2019-05-24 | 安徽工业大学 | A kind of support type phosphato-molybdic heteropolyacid low-temperature SCR catalyst and preparation method thereof |
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| CN113058647A (en) * | 2021-03-26 | 2021-07-02 | 福州大学 | Iron-substituted heteropoly acid-loaded polyphenylene sulfide denitration sulfur-resistant composite filter material |
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