CN116265113A - Integral extrusion type molecular sieve based methanol-SCR denitration catalyst and preparation method and application thereof - Google Patents
Integral extrusion type molecular sieve based methanol-SCR denitration catalyst and preparation method and application thereof Download PDFInfo
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- CN116265113A CN116265113A CN202111544395.8A CN202111544395A CN116265113A CN 116265113 A CN116265113 A CN 116265113A CN 202111544395 A CN202111544395 A CN 202111544395A CN 116265113 A CN116265113 A CN 116265113A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 82
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 62
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 238000001125 extrusion Methods 0.000 title claims abstract description 13
- 238000002360 preparation method Methods 0.000 title claims abstract description 7
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 33
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 30
- 150000003624 transition metals Chemical class 0.000 claims abstract description 22
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 20
- 239000000919 ceramic Substances 0.000 claims abstract description 11
- 239000011159 matrix material Substances 0.000 claims abstract description 10
- 239000002905 metal composite material Substances 0.000 claims abstract description 10
- 230000003647 oxidation Effects 0.000 claims abstract description 10
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 10
- 239000007789 gas Substances 0.000 claims abstract description 8
- 230000009467 reduction Effects 0.000 claims abstract description 6
- 238000001035 drying Methods 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 19
- 230000032683 aging Effects 0.000 claims description 17
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 16
- 238000006243 chemical reaction Methods 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 238000004898 kneading Methods 0.000 claims description 10
- 239000011259 mixed solution Substances 0.000 claims description 9
- 239000011148 porous material Substances 0.000 claims description 9
- 239000003365 glass fiber Substances 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 7
- 229910021641 deionized water Inorganic materials 0.000 claims description 7
- 239000000839 emulsion Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 239000004014 plasticizer Substances 0.000 claims description 7
- 235000019482 Palm oil Nutrition 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000007598 dipping method Methods 0.000 claims description 6
- 235000011187 glycerol Nutrition 0.000 claims description 6
- 239000002540 palm oil Substances 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 6
- 239000010703 silicon Substances 0.000 claims description 6
- 239000002243 precursor Substances 0.000 claims description 5
- 229920005989 resin Polymers 0.000 claims description 5
- 239000011347 resin Substances 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 3
- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 claims description 3
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 claims description 3
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 claims description 3
- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 claims description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 2
- 229910052684 Cerium Inorganic materials 0.000 claims description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 2
- 229910002651 NO3 Inorganic materials 0.000 claims description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 2
- 150000001768 cations Chemical class 0.000 claims description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 229920000609 methyl cellulose Polymers 0.000 claims description 2
- 239000001923 methylcellulose Substances 0.000 claims description 2
- 235000010981 methylcellulose Nutrition 0.000 claims description 2
- 239000002994 raw material Substances 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 9
- 239000003638 chemical reducing agent Substances 0.000 abstract description 8
- 238000011946 reduction process Methods 0.000 abstract description 3
- 238000000746 purification Methods 0.000 abstract description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 21
- 229910002091 carbon monoxide Inorganic materials 0.000 description 16
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 7
- 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 6
- 239000003546 flue gas Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- 241001408630 Chloroclystis Species 0.000 description 2
- BIGPRXCJEDHCLP-UHFFFAOYSA-N ammonium bisulfate Chemical compound [NH4+].OS([O-])(=O)=O BIGPRXCJEDHCLP-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 241000282414 Homo sapiens Species 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 238000012549 training Methods 0.000 description 1
- 239000011345 viscous material Substances 0.000 description 1
Classifications
-
- 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
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
- B01J29/72—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing iron group metals, noble metals or copper
- B01J29/76—Iron group metals or copper
-
- 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
- B01D53/864—Removing carbon monoxide or hydrocarbons
-
- 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
- B01D53/8643—Removing mixtures of carbon monoxide or hydrocarbons and nitrogen oxides
-
- B01J35/56—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/21—Organic compounds not provided for in groups B01D2251/206 or B01D2251/208
-
- 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
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
-
- 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
Abstract
The application discloses an integral extrusion type molecular sieve based methanol-SCR denitration catalyst and a preparation method and application thereof, and belongs to the field of gas purification. The denitration catalyst takes molecular sieve-based honeycomb ceramics as a matrix and comprises a nitrogen oxide reduction zone and a CO oxidation zone; and a transition metal composite oxide is loaded on a matrix in the CO oxidation zone. The catalyst has high denitration activity when methanol is used as a reducing agent, the removal efficiency of NO reaches 100% at the highest, and meanwhile, the generation of CO in the reduction process can be greatly reduced.
Description
Technical Field
The invention relates to a catalyst for removing nitrogen oxides in exhaust gas and a preparation method thereof, belonging to the field of gas purification.
Background
Fossil fuels burn to emit large amounts of NOx, causing serious environmental pollution. Among the various methods of nitrogen oxides removal, selective catalytic reduction (selective catalytic reduction, SCR) technology is one of the most important and commercially valuable methods for removing NOx from various exhaust gases. The method is that under the action of catalyst, reducing agent is added into flue gas to reduce NOx into N 2 And then discharged into the atmosphere. The reducing agent mainly used at present is NH 3 。NH 3 The SCR method has high catalytic activity and good selectivity, and various developed catalytic systems have different temperature windows and can be suitable for different application occasions. But has the problem that when the temperature of the flue gas is lower than 280 ℃, SO in the flue gas 2 Will be in combination with NH 3 The reaction generates ammonium bisulfate, and the catalyst is deactivated by blocking the pore canal of the catalyst, and the ammonium bisulfate can also block pipelines and valves to influence the stable operation of the system. Another problem with ammonia as a reducing agent is that during the actual denitration process, the operator oversprays ammonia to meet the denitration effect, resulting in a lot of unreacted NH 3 Escape into the air, which forms ammonia salt particles with acidic substances, affecting the atmosphere.
SCR methods using methanol as a reducing agent have attracted attention in recent years. Methanol is adopted to replace NH 3 The reducing agent can thoroughly solve the problems of ammonium sulfate generation and ammonia escape. The molecular sieve is a good catalytic material in the methanol-SCR method and has good denitration activity, but in order to meet the requirements of industrial application, the molecular sieve powder needs to be integrally extruded and molded. The integral extrusion type full-component honeycomb ceramic catalyst has the advantages of small resistance reduction, strong airflow scouring resistance, good stability, low cost and the like, is most widely applied in the field of industrial flue gas treatment, and is proved to be the optimal catalyst configuration for treating large-air-volume industrial flue gas.
The molecular sieve is used as a ridging material, is difficult to integrally extrude and form, and prevents the industrial application of the molecular sieve. In the extrusion process, a plurality of viscous materials and binders are often required to be added, so that the effective components in the integrally formed catalyst are reduced, the loading amount of the catalyst is required to be increased to achieve the removal effect, the equipment is huge, and the investment is increased. Drying after molecular sieve forming is also one of technical problems, such as the integral extrusion type molecular sieve honeycomb ceramic structure reported in Chinese patent No. 105618159B, the drying condition is strictly controlled in the drying process, the temperature is 30+/-5 ℃, the humidity is kept between 75 and 80 percent, the water loss rate is controlled between 0.2 and 1 percent per day, and the whole drying process lasts for more than one week, thus influencing the production efficiency.
There is also a problem in using methanol as a reducing agent in that more carbon monoxide (CO) is formed during the reaction. CO is a toxic gas for human beings and animals, and also affects the atmosphere, and the emission of CO is limited by corresponding national regulatory standards, so that CO generation in the methanol-SCR process should be avoided as much as possible.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an integral extrusion type molecular sieve based methanol-SCR denitration catalyst and a preparation method thereof, and the obtained catalyst has excellent service performance.
According to one aspect of the present invention, there is provided a denitration catalyst using a molecular sieve-based honeycomb ceramic as a matrix, the matrix including a nitrogen oxide reduction zone and a CO oxidation zone; the CO oxidation zone is positioned at one end of the matrix; the CO oxidation zone is loaded with a transition metal composite oxide;
the components of the molecular sieve-based honeycomb ceramic comprise FER type molecular sieves.
Optionally, the molecular sieve based honeycomb ceramic is provided with a plurality of parallel pore channels, the pore diameter of the pore channels is 2-8 mm, and the wall thickness of the pore channels is 0.5-1 mm;
the matrix comprises 85-90% of FER molecular sieve and 10-20% of SiO by mass of the denitration catalyst 2 5% -10% of glass fiber.
Optionally, the transition metal in the transition metal composite oxide is selected from at least two of copper, cerium, manganese, and iron; the mole ratio of any two transition metal atoms in the transition metal composite oxide is 1:4-1:1; the load of the transition metal composite oxide accounts for 1-15% of the mass of the denitration catalyst.
The load of the transition metal composite oxide is 1-15% of the mass of the denitration catalyst.
Optionally, the CO oxidation area accounts for 15% -35% of the total length of the denitration catalyst, and the balance is a nitrogen oxide reduction area.
According to an aspect of the present invention, there is provided a method for preparing the above denitration catalyst, comprising the steps of:
a) Mixing and kneading raw materials containing FER type molecular sieve, plasticizer, deionized water, organic silicon resin emulsion, palm oil and glycerin; adding glass fiber after kneading, sealing and aging, and molecular sieve catalyst pug;
b) Carrying out vacuum pugging on the molecular sieve catalyst mud material, repeatedly carrying out vacuum pugging for 5-10 times to form a catalyst mud section with smooth surface and good viscosity, and then sealing and aging the catalyst mud section of the molecular sieve; extruding, microwave drying and roasting the molecular sieve catalyst mud section to obtain a molecular sieve catalyst;
c) And (3) dipping one end of the molecular sieve catalyst into a mixed solution containing at least two transition metal precursors, and drying and roasting after dipping to obtain the denitration catalyst.
Optionally, in the step a), the plasticizer is selected from one of methylcellulose, carboxymethyl cellulose and hydroxypropyl methylcellulose;
the kneading time of the mixed materials is 3-6 hours;
the ageing time of the ageing is 24-48 hours.
Alternatively, in step a), the kneading time of the compounding is selected from 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or any value between any two points of the above;
the aging time of the aging is selected from 28 hours, 30 hours, 32 hours, 35 hours, 37 hours, 40 hours, 42 hours, 44 hours, 45 hours, 46 hours, or any value between any two of the above.
Optionally, taking FER molecular sieve mass as a reference, the addition amount of the plasticizer is 2% -6%, the addition amount of the organic silicon resin emulsion is 10% -20%, the addition amount of the glass fiber is 2% -6%, the addition amount of the palm oil is 2% -6%, the addition amount of the glycerol is 1% -3%, and the addition amount of the deionized water is 30% -50%;
the water content of the molecular sieve catalyst pug is 25-30%.
Optionally, in the step b), the vacuum degree of the vacuum pugging is-0.08 to-0.095 Mpa;
the ageing time of the ageing is 24-48 hours;
the diameter of the molecular sieve catalyst mud section is 50mm.
Optionally, in step b), the aging time is selected from 28 hours, 30 hours, 32 hours, 35 hours, 37 hours, 40 hours, 42 hours, 44 hours, 45 hours, 46 hours, or any value between any two of the above.
Optionally, in the step b), the extruder used for extrusion is selected from one of a ram extruder, a continuous screw extruder or a twin screw extruder;
the microwave power of the microwaves is 500 w-1000 w, and the microwave time is 3-5 minutes;
the drying temperature of the drying is 100-120 ℃ and the drying time is 8-12 hours;
the roasting temperature of the roasting is 500-700 ℃ and the roasting time is 4-6 hours.
Optionally, in step b), the microwave power of the microwave is selected from 500w to 1000w, or any value between any two points; the microwave time is selected from 3.5 minutes, 3.8 minutes, 4 minutes, 4.2 minutes, 4.5 minutes, 4.8 minutes, or any value between any two points;
the roasting temperature of the roasting is selected from 520 ℃, 550 ℃, 570 ℃, 580 ℃, 600 ℃, 620 ℃, 650 ℃, 670 ℃, 690 ℃ or any value between any two points; the calcination time is selected from 4.2 hours, 4.5 hours, 4.7 hours, 4.9 hours, 5 hours, 5.3 hours, 5.5 hours, 5.8 hours, or any value between any two of the above.
Optionally, in step c), the impregnating height is 15% -35% of the total length of the molecular sieve catalyst, and the impregnating time is 1-5 minutes;
the roasting temperature is 500 ℃ and the roasting time is 2-4 hours.
Optionally, in step c), the firing temperature of the firing is selected from, or any value between any two points above; the calcination time is selected from 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours, or any value between any two points.
Optionally, the transition metal precursor is selected from at least one of nitrate and acetate of transition metal; the concentration of the metal cations in the mixed solution is 1 mol/L-5 mol/L.
According to one aspect of the invention, the denitration catalyst and the application of the denitration catalyst prepared by the preparation method in catalyzing the reaction of selectively reducing nitrogen oxides by methanol are provided.
Optionally, introducing the mixed gas containing nitrogen oxides and methanol into a reactor containing the denitration catalyst for reaction; the reaction conditions are as follows: the volume airspeed is 2000-12000 h -1 The temperature is 150-500 ℃.
Optionally, the volume airspeed is 4000-6000 h -1 The temperature is 200-300 ℃.
Alternatively, the volume space velocity is selected from 2500h -1 、3000h -1 、3500h -1 、5000h -1 、5500h -1 、6500h -1 、7000h -1 、7500h -1 、8000h -1 、8500h -1 、9000h -1 、9500h -1 Or any value between any two points; the temperature is selected from 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃ or any value between any two points.
As an embodiment of the present application, there is provided a method for preparing a denitration catalyst, including the steps of:
a) Mixing FER molecular sieve and plasticizer, adding deionized water, organic silicon resin emulsion, palm oil, glycerol and glass fiber, and kneading; sealing and aging after kneading, and molecular sieve catalyst pug;
b) Performing vacuum pugging on molecular sieve catalyst pugs, and sealing and ageing after repeating the vacuum pugging for 5-10 times to obtain molecular sieve catalyst pugs; extruding, microwave drying and roasting the molecular sieve catalyst mud section to obtain a molecular sieve catalyst;
c) And (3) dipping one end of the molecular sieve catalyst into a mixed solution containing at least two transition metal precursors, and drying and roasting after dipping to obtain the denitration catalyst.
The invention has the following beneficial effects:
the molecular sieve extrusion structure has molecular sieve content up to 80% and high denitration activity; the drying is carried out by adopting microwaves, the dried blank body has no crack, the drying speed is increased, the production speed is increased, and the energy consumption is reduced; the end carries out transition metal loading, so that CO generated in the reduction process is greatly eliminated.
The integral extrusion type molecular sieve based methanol-SCR catalyst provided by the invention has high denitration activity when methanol is used as a reducing agent, the NO removal efficiency can reach 90-100% in a certain temperature range, and meanwhile, the generation of CO in the reduction process can be greatly reduced.
Detailed description of the preferred embodiments
The following detailed description of the invention is merely a preferred embodiment of the invention and is not intended to limit the scope of the invention.
Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially. Unless otherwise specified, the test methods all use conventional methods, and the instrument settings all use manufacturer recommended settings.
Wherein, FER molecular sieves are purchased from Tianjin Nanjing university; methyl silicone resin emulsion is purchased from Hubei four-sea chemical plant.
Example 1
800g of FER molecular sieve was weighed, and 32g of hydroxypropyl methylcellulose was added to a kneader for dry blending. After 30 minutes 160g of methyl silicone emulsion, 32g of palm oil, 16g of glycerol, 32g of glass fibers and 400g of deionized water were added. Kneading for 2 hours until the materials are uniform, and obtaining the molecular sieve catalyst pug with the water content of 30 percent. After the molecular sieve catalyst pug is aged for 24 hours, vacuum pugging is started, and the vacuum degree is-0.09 Mpa. Placing the pug after training for 24 hours, and extruding the pug through a porous die by using a hydraulic piston type extruder to form the honeycomb structure. The mold specification parameters used were as follows: after the well-refined mud is placed for 24 hours, a section of the well-aged molecular sieve catalyst mud section is cut, and the section is put into a hydraulic piston type extruder to be extruded through a porous die to form a honeycomb structure. The mold specification parameters used were as follows:
| cross-sectional dimension (mm) 2 ) | Number of holes | Hole width (mm) | Inner wall thickness (mm) | Outer wall thickness (mm) |
| 22.3×22.3 | 5×5 | 3.3 | 0.9 | 1.1 |
The extruded honeycomb body was dried in a microwave oven for 5 minutes at 750w for rapid setting, and then transferred to a drying oven for drying at 100℃for 12 hours to obtain a dried green body, which was then cut into small pieces having a length of 4.5cm, and baked in a muffle furnace at 500℃for 4 hours to obtain a molecular sieve-based honeycomb ceramic structure.
Weigh 20g Cu (NO) 3 ) 2 ·3H 2 O and 35.9g Ce (NO) 3 ) 3 ·6H 2 O was added with 30g of deionized water to prepare a mixed solution. And (3) adding the solution into a small beaker, controlling the liquid level to enable the height of the metal-impregnated honeycomb body to be 0.8cm, immersing one end of the burned molecular sieve-based honeycomb ceramic structure body into the solution for 5 seconds, taking out, quickly drying by hot air, and putting into a muffle furnace for roasting at 500 ℃ for 2 hours to obtain the molecular sieve-based methanol-SCR denitration catalyst.
Example 2
The catalyst was prepared essentially as in example 1, except that the die specifications used in the extrusion process were as follows:
| cross-sectional dimension (mm) 2 ) | Number of holes | Hole width (mm) | Inner wall thickness (mm) | Outer wall thickness (mm) |
| 21.2×21.2 | 3×3 | 5.7 | 0.9 | 1.15 |
Example 3
The catalyst was prepared essentially as in example 1, except that the die specifications used in the extrusion process were as follows:
| cross-sectional dimension (mm) 2 ) | Number of holes | Hole width (mm) | Inner wall thickness (mm) | Outer wall thickness (mm) |
| 21.4×21.4 | 9×9 | 1.8 | 0.45 | 0.8 |
Example 4
The catalyst was prepared substantially as in example 1 except that in the step of impregnating the mixed solution of copper nitrate and cerium nitrate, the liquid level was controlled so that the height of the metal-impregnated honeycomb body was 1.5cm.
Example 5
The catalyst was prepared substantially as in example 1 except that in the step of impregnating the mixed solution of copper nitrate and cerium nitrate, the liquid level was controlled so that the height of the metal-impregnated honeycomb body was 0.4cm.
Comparative example 1
The catalyst was prepared essentially as in example 1, except that the tail end was not impregnated with a mixed solution of copper nitrate and cerium nitrate.
Test example 6
The catalysts prepared in examples 1 to 5 and comparative example 1 were evaluated for activity. The method for testing the denitration activity of the catalyst comprises the following steps: the prepared monolithic honeycomb catalyst is placed in a fixed bed reactor. Preparing a nail with a certain concentrationThe aqueous alcohol solution was evaporated in an evaporator by a pump and mixed with other component gases, and the flow rate of the pump was controlled so that the water vapor concentration was 5% and the methanol concentration was 1000ppm. The final feed gas composition was: 500ppm NO+1000ppm CH 3 OH+6％O 2 +5％H 2 O+N 2 Balance, flow was 1.5L/min. Respectively detecting the NO concentration of the inlet and the outlet, thereby calculating the conversion rate of NO and obtaining the denitration efficiency X of the catalyst NO The reaction outlet CO concentration was also detected. Table 1 shows the denitration efficiency and CO formation of several catalysts at 200-300 ℃.
Table 1 denitration efficiency of each catalyst and CO concentration at the reaction outlet
As can be seen from the data in the attached table 1, the catalyst prepared by the invention has good denitration activity, and meanwhile, the generation of CO is greatly reduced, and the concentration of CO generated by the reaction can be controlled to be less than 20ppm under the condition that the conversion rate of NO is 100%.
The foregoing description is only a few examples of the present application and is not intended to limit the present application in any way, and although the present application is disclosed in the preferred examples, it is not intended to limit the present application, and any person skilled in the art may make some changes or modifications to the disclosed technology without departing from the scope of the technical solution of the present application, and the technical solution is equivalent to the equivalent embodiments.
Claims (10)
1. The denitration catalyst is characterized in that the denitration catalyst takes molecular sieve-based honeycomb ceramics as a matrix, and the matrix comprises a nitrogen oxide reduction zone and a CO oxidation zone; the CO oxidation zone is positioned at one end of the matrix; the CO oxidation zone is loaded with a transition metal composite oxide;
the components of the molecular sieve-based honeycomb ceramic comprise FER type molecular sieves.
2. The denitration catalyst according to claim 1, wherein the molecular sieve-based honeycomb ceramic has a plurality of parallel pore channels, the pore diameter of the pore channels is 2-8 mm, and the wall thickness of the pore channels is 0.5-1 mm;
the matrix comprises 85 to 90 percent of FER molecular sieve and 10 to 20 percent of SiO based on the mass of the denitration catalyst 2 5% -10% of glass fiber;
the ratio of the FER molecular sieve to the silicon to the aluminum is 2-500.
3. The denitration catalyst according to claim 1, wherein the transition metal in the transition metal composite oxide is selected from at least two of copper, cerium, manganese, and iron;
the mole ratio of any two transition metal atoms in the transition metal composite oxide is 1:4-1:1
The load of the transition metal composite oxide accounts for 1-15% of the mass of the denitration catalyst.
4. The denitration catalyst of claim 1, wherein the CO oxidation zone is 15% to 35% of the total length of the denitration catalyst, and the balance is a nitrogen oxide reduction zone.
5. A method for preparing the denitration catalyst as claimed in any one of claims 1 to 4, characterized by comprising the steps of:
a) Mixing and kneading raw materials containing FER type molecular sieve, plasticizer, deionized water, organic silicon resin emulsion, palm oil and glycerin; adding glass fiber after kneading, sealing and aging, and molecular sieve catalyst pug;
b) Carrying out vacuum pugging on molecular sieve catalyst mud materials, sealing and aging to obtain molecular sieve catalyst mud sections; extruding, microwave drying and roasting the molecular sieve catalyst mud section to obtain a molecular sieve catalyst;
c) And (3) dipping one end of the molecular sieve catalyst into a mixed solution containing at least two transition metal precursors, and drying and roasting after dipping to obtain the denitration catalyst.
6. The method according to claim 5, wherein in the step a), the plasticizer is one selected from the group consisting of methyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose;
the kneading time of the mixed materials is 3-6 hours;
the ageing time of the ageing is 24-48 hours;
preferably, the FER molecular sieve is taken as a reference, the addition amount of the plasticizer is 2-6%, the addition amount of the organic silicon resin emulsion is 10-20%, the addition amount of the glass fiber is 2-6%, the addition amount of the palm oil is 2-6%, the addition amount of the glycerol is 1-3%, and the addition amount of the deionized water is 30-50%;
the water content of the molecular sieve catalyst pug is 25-30%.
7. The method according to claim 5, wherein in the step b), the vacuum degree of the vacuum pugging is-0.08 to-0.095 Mpa;
the ageing time of the ageing is 24-48 hours;
the diameter of the molecular sieve catalyst mud section is 50mm.
8. The method according to claim 5, wherein in the step b), the extruder used for the extrusion is selected from one of a ram extruder, a continuous screw extruder and a twin screw extruder;
the microwave power of the microwaves is 500 w-1000 w, and the microwave time is 3-5 minutes;
the drying temperature of the drying is 100-120 ℃ and the drying time is 8-12 hours;
the roasting temperature of the roasting is 500-700 ℃ and the roasting time is 4-6 hours.
9. The method according to claim 5, wherein in step c), the impregnating height is 15% to 35% of the total length of the molecular sieve catalyst, and the impregnating time is 1 minute to 5 minutes;
the roasting temperature of the roasting is 500 ℃ and the roasting time is 2-4 hours;
preferably, the transition metal precursor is selected from at least one of nitrate and acetate of transition metal; the concentration of the metal cations in the mixed solution is 1 mol/L-5 mol/L.
10. Use of the denitration catalyst as claimed in any one of claims 1 to 4 and the denitration catalyst prepared by the preparation method as claimed in any one of claims 5 to 9 in catalyzing a reaction for selectively reducing nitrogen oxides in methanol;
preferably, introducing the mixed gas containing nitrogen oxides and methanol into a reactor containing the denitration catalyst for reaction; the reaction conditions are as follows: the volume airspeed is 2000-12000 h -1 The temperature is 150-500 ℃;
preferably, the volume space velocity is 4000-6000 h -1 The temperature is 200-300 ℃.
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