CN115518675A - With low temperature NO x SCR catalyst with adsorption function and application thereof - Google Patents
With low temperature NO x SCR catalyst with adsorption function and application thereof Download PDFInfo
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- CN115518675A CN115518675A CN202211111496.0A CN202211111496A CN115518675A CN 115518675 A CN115518675 A CN 115518675A CN 202211111496 A CN202211111496 A CN 202211111496A CN 115518675 A CN115518675 A CN 115518675A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 139
- 238000001179 sorption measurement Methods 0.000 title claims abstract description 50
- 238000000576 coating method Methods 0.000 claims abstract description 215
- 239000011248 coating agent Substances 0.000 claims abstract description 212
- 239000000203 mixture Substances 0.000 claims abstract description 55
- 239000000758 substrate Substances 0.000 claims abstract description 55
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 47
- 239000002808 molecular sieve Substances 0.000 claims description 29
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 29
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 claims description 28
- 238000011068 loading method Methods 0.000 claims description 26
- 230000009467 reduction Effects 0.000 claims description 25
- 229910052878 cordierite Inorganic materials 0.000 claims description 18
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims description 18
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 16
- 230000000274 adsorptive effect Effects 0.000 claims description 13
- 230000002829 reductive effect Effects 0.000 claims description 12
- 239000010949 copper Substances 0.000 claims description 11
- 229910052802 copper Inorganic materials 0.000 claims description 6
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Chemical compound [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 claims description 6
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- 239000004480 active ingredient Substances 0.000 claims description 5
- 239000010953 base metal Substances 0.000 claims description 5
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- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims description 5
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- 239000005751 Copper oxide Substances 0.000 claims description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 4
- 239000000292 calcium oxide Substances 0.000 claims description 4
- 229910000431 copper oxide Inorganic materials 0.000 claims description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 4
- 239000000395 magnesium oxide Substances 0.000 claims description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 4
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- UNYSKUBLZGJSLV-UHFFFAOYSA-L calcium;1,3,5,2,4,6$l^{2}-trioxadisilaluminane 2,4-dioxide;dihydroxide;hexahydrate Chemical compound O.O.O.O.O.O.[OH-].[OH-].[Ca+2].O=[Si]1O[Al]O[Si](=O)O1.O=[Si]1O[Al]O[Si](=O)O1 UNYSKUBLZGJSLV-UHFFFAOYSA-L 0.000 claims description 3
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- YBMRDBCBODYGJE-UHFFFAOYSA-N germanium oxide Inorganic materials O=[Ge]=O YBMRDBCBODYGJE-UHFFFAOYSA-N 0.000 claims description 3
- 229910052677 heulandite Inorganic materials 0.000 claims description 3
- 229910052746 lanthanum Inorganic materials 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims description 3
- PVADDRMAFCOOPC-UHFFFAOYSA-N oxogermanium Chemical compound [Ge]=O PVADDRMAFCOOPC-UHFFFAOYSA-N 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 3
- 150000002910 rare earth metals Chemical class 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910052678 stilbite Inorganic materials 0.000 claims description 3
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 3
- 229910001887 tin oxide Inorganic materials 0.000 claims description 3
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- 229910052727 yttrium Inorganic materials 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 2
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- 239000010970 precious metal Substances 0.000 claims 2
- 229910052759 nickel Inorganic materials 0.000 claims 1
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 102
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- 230000000052 comparative effect Effects 0.000 description 40
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 11
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- 238000001354 calcination Methods 0.000 description 10
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- 229910000510 noble metal Inorganic materials 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 5
- 239000011230 binding agent Substances 0.000 description 5
- 239000000084 colloidal system Substances 0.000 description 5
- 238000011056 performance test Methods 0.000 description 5
- 229910052717 sulfur Inorganic materials 0.000 description 5
- 239000011593 sulfur Substances 0.000 description 5
- 239000003463 adsorbent Substances 0.000 description 4
- 239000000446 fuel Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
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- 238000011069 regeneration method Methods 0.000 description 3
- 229910001961 silver nitrate Inorganic materials 0.000 description 3
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 2
- 208000028659 discharge Diseases 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 244000304337 Cuminum cyminum Species 0.000 description 1
- 241000282326 Felis catus Species 0.000 description 1
- AVXURJPOCDRRFD-UHFFFAOYSA-N Hydroxylamine Chemical class ON AVXURJPOCDRRFD-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
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- 238000006555 catalytic reaction Methods 0.000 description 1
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- 235000013842 nitrous oxide Nutrition 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 1
- MMKQUGHLEMYQSG-UHFFFAOYSA-N oxygen(2-);praseodymium(3+) Chemical compound [O-2].[O-2].[O-2].[Pr+3].[Pr+3] MMKQUGHLEMYQSG-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
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Images
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
- B01J29/74—Noble metals
-
- 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
-
- 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
- B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
-
- 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
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/74—Iron group metals
- B01J23/745—Iron
-
- 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
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
- B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/01—Engine exhaust gases
-
- 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
- B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
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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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Combustion & Propulsion (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Catalysts (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
The invention discloses a low-temperature NO X The catalyst product adopts a flow-through type monolith substrate, a zoned coating catalyst is arranged on the substrate and comprises a first zone coating, a second zone coating and a third zone coating, the first zone coating is tightly attached to the wall of the substrate and positioned at the air inlet end of the substrate, the second zone coating is tightly attached to the wall of the substrate and positioned at the air outlet end of the substrate, the sum of the lengths of the first zone coating and the second zone coating is equal to the total length of the substrate, and the third zone coating is positioned on the second zone coating and has the same length as the second zone coating; first zone coatingComprising a passive nox adsorption catalyst composition, the second zone coating comprising NO 2 Reducing the catalyst composition, the third zone coating comprising NO X Reducing the catalyst composition; the first zone coating absorbs NO in the exhaust gas at a temperature below 150 DEG C X And release NO above 250 ℃ X (ii) a Coating the second zone with NO X A certain proportion of NO 2 Conversion to NO 2 And NO concentration ratio of 0.8-1.2: 1; third zone coating NO X Conversion to N 2 。
Description
Technical Field
The invention belongs to the field of catalysts for post-treatment of tail gas of fuel vehicles, and particularly relates to a catalyst with low-temperature NO X An SCR catalyst with adsorption function and application thereof.
Background
The U.S. Environmental Protection Agency (EPA) regulates nitrogen dioxide (NO) based on the negative climate effects of nitrogen oxides 2 ) Nitrogen monoxide (NO) and dinitrogen monoxide (N) 2 O) is collectively referred to as NO X . The exhaust gas of diesel vehicles with high air-fuel ratio is NO X The main source of emissions. As a typical lean-burn engine, diesel vehicles typically employ a combination of selective reduction catalytic SCR technology and cooled exhaust gas recirculation technology to meet stringent emission regulations. However, the SCR catalyst can exert good NO only when the exhaust gas temperature reaches the light-off temperature (more than 200 ℃ C.) or higher X And (5) emission reduction effect. The tail gas temperature in the cold start stage of the diesel vehicle is lower than 180 ℃ and lasts for about 3min, during which NO is X The emissions are discharged into the air with little or no treatment. Cold start exhausted NO X Contribute to the total NO X 80% of the emissions. In addition, in order to improve fuel economy, advanced combustion, engine miniaturization, turbocharging and other technologies are continuously updated and applied to the diesel engine, so that the exhaust temperature is lowered, and the duration and the strength of the cold start effect are more obvious.
For solving NO in tail gas in cold starting stage X Emission problem, passive NO X Sorbent (PNA) is generated at the same time, P is generated when SCR is low in activityNA adsorption of NO X With the rise of the temperature of the tail gas, the downstream SCR can be efficiently catalyzed, and the PNA can convert NO X Rapidly releases and recovers NO X And (4) adsorption function.
Cummins proposes an organizational structure with PNA, i.e., DOC + PNA + SCRF (i.e., coating SCR catalyst on a particulate trap (DPF)), CC-SCR. The system has excellent NO X Emission reduction effect, but relates to 5 post-processing units outside the machine, the system architecture is complex, the implementation cost is high, and huge pressure is brought to packaging and arrangement. Zhuangxinwan feng discloses a DOC and PNA coupling scheme, called DCSC unit, and has conducted a number of patented layouts for the different framework structure molecular sieve components of DCSC. The unit has the defects that because the DCSC contains a large amount of noble metal active components, the DCSC is unevenly distributed in the hierarchical pore canal of the carrier, the DCSC is easy to agglomerate at high temperature to form large particles, the charge density of the agglomerated particles is high, electrons are easy to be given, and NO in the original discharge is treated X The oxidation effect is far greater than the adsorption effect, so that the DCSC shows passive NO X Low adsorption capacity and NO due to DCSC treatment 2 Much higher than NO, not favorable for subsequent NH 3 SCR reacts rapidly, reducing the selective catalytic reduction treatment rate.
Disclosure of Invention
In order to solve the problem of NO in tail gas in cold starting stage in the prior art X The invention provides the following technical scheme for solving the discharge problem:
in a first aspect, the present invention provides a composition having low temperature NO X The SCR catalyst with the adsorption function adopts a flow-through type monolith substrate, a zoned coating catalyst is arranged on the substrate, the zoned coating catalyst comprises a first zone coating, a second zone coating and a third zone coating, wherein the first zone coating is tightly attached to the wall of the substrate hole and positioned at the air inlet end of the substrate, the second zone coating is tightly attached to the wall of the substrate hole and positioned at the air outlet end of the substrate, the sum of the lengths of the first zone coating and the second zone coating is equal to the total length of the substrate, and the third zone coating is positioned on the second zone coating and has the same length as the second zone coating; the first zone coating comprises a passive nitrogen oxide adsorption catalyst composition and the second zone coating comprises NO 2 The reduction of the catalyst composition is carried out,the third zone coating comprises NO X Reducing the catalyst composition; the first zone coating absorbs NO in the exhaust gas at a temperature below 150 DEG C X And release NO above 250 ℃ X (ii) a Coating the second zone with NO X In a certain proportion of NO 2 Conversion to NO 2 And NO concentration ratio of 0.8-1.2: 1; third zone coating of NO X Conversion to N 2 。
In some embodiments provided by the present invention, the sum of the third region coating thickness and the second region coating thickness is equal to the first region coating thickness.
In some embodiments provided herein, the length of the second zone coating and the third zone coating is 30% to 70%, preferably 70%, of the total length of the substrate.
In some embodiments provided herein, the passive nox adsorber catalyst composition, NO 2 Reductive catalyst composition, NO X The ratio of the supported amount of the reduction catalyst composition is 30 to 50:10:95 to 120.
In some embodiments provided herein, the first zone coating has an loading of the passive nitroxide adsorption catalyst composition of 30 to 50g/L; NO in the coating of the second zone 2 The loading of the reduction catalyst composition is 10 +/-2 g/L; NO in third zone coating X The loading of the reduction catalyst composition is 95-120 g/L.
In some embodiments of the present invention, the substrate is one of cordierite, silicon carbide, and metal.
In some embodiments of the present invention, the metal material is one of Fe-Cr-Ni alloy, co-Cr-Ni alloy, and Ni-Cr-Mo alloy.
In some embodiments provided herein, a passive nox adsorber catalyst composition includes a noble metal active component and a first adsorbent refractory support, the noble metal active component being at least one of Pd, ag, co, and the first adsorbent refractory support being a first molecular sieve or a metal oxide.
In some embodiments provided herein, the passive nox adsorber catalyst composition further comprises a base metal that is at least one of Mn, co, zr, ni, or a rare earth metal that is Ce or La.
In some embodiments provided herein, NO 2 The reductive catalyst composition comprises NO 2 Reducing the active ingredient and a second adsorptive refractory carrier, NO 2 The reduction active component is one or more of ferric oxide, cobalt oxide, copper oxide, barium oxide, calcium oxide, magnesium oxide, strontium oxide, tin oxide and germanium oxide, and the second adsorptive refractory carrier is silicon oxide or gamma-aluminum oxide.
In some embodiments provided herein, NO X The reductive catalyst composition comprises NO X Reducing the active ingredient and a third adsorptive refractory carrier, NO X The reducing active component is one or more of Cu, mn, V, fe, co, W, ni, zn, ti, cr, Y, zr, nb and Mo, and the third adsorptive refractory carrier includes one or symbiotic mixture of analcime, chabazite, heulandite, stilbite, erionite, mordenite, scolecite and natrolite.
In a second aspect, the present invention provides a method comprising providing a low temperature NO X Adsorption function's SCR catalyst's lean burn engine exhaust treatment device.
Compared with the prior art, the PNA catalyst and NO are used in the invention 2 The reduction catalyst and the SCR catalyst are loaded on the same substrate, and the PNA catalyst solves the problem of low-temperature cold start NO X Emission problem, NO 2 The reduction catalyst improves the oxidation side reaction of the PNA catalyst, on one hand, NO and NO in tail gas are ensured 2 The balance of (a) is close to 1:1, promoting fast SCR reaction, on the other hand, avoiding low temperature NO X Excessive NO formation by adsorption 2 From the source, control N 2 And (4) O generation reaction.
Drawings
FIG. 1 coating scheme one of comparative examples 3 to 5 of the present invention.
FIG. 2 coating scheme two used in examples 1-3 of the present invention.
FIG. 3 coating scheme three used in comparative examples 6 to 7 of the present invention.
Detailed Description
The invention is further described in the following examples, which are intended to better illustrate the technical solution of the invention and not to limit the claims. The invention is not limited to the specific examples and embodiments described herein. It will be apparent to those skilled in the art that further modifications and improvements may be made without departing from the spirit and scope of the invention, and these are intended to be covered by the appended claims.
The existing tail gas treatment system of the lean-burn engine comprises an independent PNA unit and an independent SCR unit, wherein the PNA unit can oxidize 40% -90% of NO into NO 2 Thereby resulting in NO and NO 2 The ratio is much less than 1. The invention forms low temperature NO by coating PNA catalyst and SCR catalyst on different areas of the same monolithic substrate X Adsorption function of SCR catalyst and addition of NO on substrate 2 A reduction catalyst coating for oxidation of more than 90% of NO to NO 2 Re-reduction to NO, thereby regulating NO and NO 2 The ratio is close to 1.
The invention provides a low temperature NO X The SCR catalyst product adopts a flow-through monolith substrate, a zoned coating catalyst is arranged on the substrate, the zoned coating catalyst comprises a first zone coating, a second zone coating and a third zone coating, wherein the first zone coating is tightly attached to the hole wall of the substrate and is positioned at the air inlet end of the substrate, the second zone coating is tightly attached to the hole wall of the substrate and is positioned at the air outlet end of the substrate, the sum of the lengths of the first zone coating and the second zone coating is equal to the total length of the substrate, and the third zone coating is positioned on the second zone coating and has the same length as the second zone coating; the first zone coating comprises a passive nox adsorber catalyst composition and the second zone coating comprises NO 2 Reducing the catalyst composition, the third zone coating comprising NO X Reducing the catalyst composition; the first zone coating absorbs NO in the exhaust gas at a temperature below 150 DEG C X And release NO above 250 ℃ X (ii) a Coating the second zone with NO X A certain proportion of NO 2 Conversion to NO 2 And NO at a concentration ratio of 0.8-1.2: 1; third zone coating NO X Transformation ofIs N 2 。
In some embodiments provided herein, the passive nox adsorber catalyst composition, NO 2 Reduction catalyst composition, NO X The ratio of the supported amount of the reducing catalyst composition is 30 to 50:10:95 to 120. In the proportion range, the second zone coating is ensured to partially generate NO 2 Reduction to NO enables the formation of NO and NO 2 The ratio of (a) to (b) is adjusted to approach 1.
In some embodiments provided by the present invention, the sum of the third region coating thickness and the second region coating thickness is equal to the first region coating thickness.
In some embodiments provided herein, the first zone coating has an loading of the passive nitrogen oxide adsorbing catalyst composition of 30 to 50g/L; NO in the coating of the second zone 2 The loading of the reduction catalyst composition is 10 +/-2 g/L; NO in third zone coating X The loading of the reduction catalyst composition is 95-120 g/L. The loading amount of the passive oxynitride adsorption catalyst composition in the first zone coating needs to balance low-temperature adsorption performance and system backpressure, so the loading amount is set to be 30-50 g/L, and when the loading amount is lower than 30g/L, NO is discharged from the tail of the cold start of an engine X Can not be sufficiently adsorbed, and NO can be further reduced by increasing the loading amount X Concentration, when higher than 50g/L, NO in cold start X Conversion efficiency can not be further improved, and system backpressure is increased due to reverse rotation, so that fuel economy of the engine is affected. Second zone coating NO 2 The loading amount of the reduction catalyst composition is controlled to 10 + -2 g/L, and the main consideration is that the reduction catalyst composition is NO 2 The reduction efficiency of (a).
In some embodiments of the present invention, the substrate is one of cordierite, silicon carbide, and metal.
In some embodiments of the present invention, the metal material is one of Fe-Cr-Ni alloy, co-Cr-Ni alloy, and Ni-Cr-Mo alloy.
In some embodiments provided herein, a passive nox adsorber catalyst composition includes a noble metal active component and a first adsorbent refractory support, the noble metal active component being at least one of Pd, ag, co, and the first adsorbent refractory support being a first molecular sieve or a metal oxide. The first molecular sieve is one of small pore molecular sieve with eight-membered ring structure, medium pore molecular sieve with ten-membered ring structure and large pore molecular sieve with twelve-membered ring structure, and the first molecular sieve can be one of BEA, FAU, MFI, CHA, LTA, AEI, FER and MCM, especially one of Beta, HEBA, SSZ-13, ZSM-5, SSZ-39 and HZSM-11. The grain size of the first molecular sieve is 0.01-10 mu m, and Si/Al = 1-30. Further, the grain size of the first molecular sieve is 100-1000 nm. The metal oxide refers to one of gamma-alumina, cerium oxide, praseodymium oxide, zirconium oxide and tungsten oxide and composite oxides thereof.
In some embodiments provided herein, the passive nox adsorber catalyst composition further comprises a base metal that is at least one of Mn, co, zr, ni, or a rare earth metal that is Ce or La.
Preferably, the noble metal content is 0.1wt% to 5wt% of the passive oxynitride adsorbing catalyst composition, and the base metal content is 0.1wt% to 1wt% of the passive oxynitride adsorbing catalyst composition.
In some embodiments provided herein, NO 2 The reducing catalyst composition comprises NO 2 Reducing the active ingredient and a second adsorptive refractory carrier, NO 2 The reduction active component is one or more of ferric oxide, cobalt oxide, copper oxide, barium oxide, calcium oxide, magnesium oxide, strontium oxide, tin oxide and germanium oxide, and the second adsorptive refractory carrier is silicon oxide or gamma-alumina. NO 2 The reductive catalyst composition is preferably a symbiotic mixture of at least one of iron oxide, cobalt oxide, copper oxide, barium oxide, calcium oxide, and magnesium oxide and one or both of silicon oxide and gamma-alumina.
In some embodiments provided herein, NO X The reducing catalyst composition comprises NO X Reducing the active ingredient and a third adsorptive refractory carrier, NO X The reducing active component is one or more of Cu, mn, V, fe, co, W, ni, zn, ti, cr, Y, zr, nb and Mo, and the third adsorptive refractory carrier includes analcime, chabazite, heulandite, stilbite, erionite, mordeniteOne or symbiotic mixture of stone, calcium zeolite and sodium zeolite. More preferably, the third adsorptive refractory carrier is one or a symbiotic mixture of BEA, FAU, MFI, CHA, LTA, AEI, MOR, KFI, ROH framework, NO X The reduction active component is one or a symbiotic mixture of Cu, fe, W, ti, zr and Mo.
In a second aspect, the present invention provides a method comprising providing a low temperature NO X A lean burn engine tail gas treatment device of an SCR catalyst with an adsorption function. With the composite catalyst provided by the application, the PNA unit does not need to be additionally added, and preferably, the low-temperature NO is contained in the PNA unit X The lean burn engine tail gas treatment device of the SCR catalyst with the adsorption function is provided with a DOC unit, a DPF unit and low-temperature NO according to the tail gas flowing direction X SCR catalyst unit and ASC unit of adsorption function.
The following table shows the low temperature NO provided by the present invention X Adsorption-functional SCR catalyst examples 1 to 3 and comparative examples 1 to 7.
TABLE 1
TABLE 1 (continue)
Example 1:
this example provides a method of producing a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: adding palladium nitrate into FER microporous molecular sieve slurry with the grain size of 800nm and Si/Al =25, uniformly stirring, adding 10% of alumina adhesive, adding water to adjust the solid content of the slurry to 30%, and obtaining first slurry. The first slurry was coated onto a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter straight-through cordierite substrate from the inlet end by top feed, 40Hz negative pressure suction, loaded on a dry weight of 30g/L and coated at a length of 1.5 inches, dried and calcined in air at 550 ℃ to form a first zone coating.
S2: and adding water into the gamma-alumina with the particle size of 1-3 mu m for mixing to prepare alumina suspension, adding the nano barium oxide colloid suspension according to the mass ratio of the alumina to the barium oxide of 6. The second slurry was applied to the other end of the straight through cordierite substrate from the outlet end in a top-fed, 40Hz negative pressure suction manner, over a 3.5 inch coating length with a dry weight of 10g/L, dried and calcined in air at 550 c to form the second zone coating, as shown in fig. 2, where the sum of the first zone coating length and the second zone coating length was the total length of the substrate and the first zone coating thickness was greater than the second zone coating thickness.
S3: adding water into an SSZ-39 molecular sieve containing 3.5% of Cu, stirring and dispersing for 30min, then adding 5% of alumina binder, and adding water to adjust the solid content to 30% to obtain third slurry. Coating a third slurry on the surface of the coating of the second area from the gas outlet end in a manner of feeding and sucking at 40Hz negative pressure, wherein the coating length is 3.5 inches, the whole coating of the second area is covered, the dry weight of the third slurry is 100g/L, and the third slurry is calcined in air at 550 ℃ after being dried to form a third area coating, namely a catalyst product, which is marked as catalyst 2#.
Example 2:
this example provides a method of producing a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: adding silver nitrate into SSZ-13 microporous molecular sieve slurry with the atomic ratio Si/Al =14 and the grain size of 100nm, uniformly stirring, adding 10% of alumina binder, and adding water to adjust the solid content of the slurry to 30% to obtain first slurry. The first slurry was coated onto a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter straight-through cordierite substrate from the inlet end by top feed, 40Hz negative pressure suction, loaded on a dry weight of 40g/L, coated over a length of 2 inches, dried and calcined in air at 550 ℃ to form the first zone coating.
S2: adding water into gamma-alumina with the particle size of 1-3 mu m for mixing to prepare alumina suspension, adding nano iron oxide suspension according to the mass ratio of the alumina to the iron oxide of 3. The second slurry was applied to the other end of the straight through cordierite substrate from the outlet end in a top-fed, 40Hz negative pressure suction manner, over a 3 inch length, at a dry loading of 10g/L, dried and then calcined in air at 550 c to form the second zone coating, as shown in fig. 2, where the sum of the lengths of the first zone coating and the second zone coating is the total length of the substrate and the first zone coating has a greater thickness than the second zone coating.
S3: adding water into a BEA molecular sieve with the D50 of 5-8 mu m and the Fe content of 5.2%, stirring and dispersing for 30min, then adding 10% of alumina adhesive, and adding water to adjust the solid content to 30% to obtain third slurry. And coating a third slurry on the surface of the coating of the second area from the air outlet end in a manner of feeding and 40Hz negative pressure suction, wherein the coating length is 3.5 inches, the whole coating of the second area is covered, the dry weight of the third slurry is 120g/L, and the third slurry is dried and calcined in air at 550 ℃ to form a third area coating, so that the catalyst product is obtained.
Example 3:
this example provides a method of producing a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: palladium nitrate is added into FER microporous molecular sieve slurry with the grain size of 800nm and the Si/Al =25, after uniform stirring, 10% of alumina adhesive is added, and water is added to adjust the solid content of the slurry to 30%, so as to obtain first slurry. From the inlet end, the slurry was coated onto a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter straight-through cordierite substrate by top feed, 40Hz negative pressure suction, loaded on a dry weight of 35g/L, coated over a 2 inch length, dried and calcined in air at 550 ℃ to form a first zone coating.
S2: and adding water into the gamma-alumina with the particle size of 1-3 mu m for mixing to prepare an alumina suspension, adding the nano barium oxide colloid suspension according to the mass ratio of the alumina to the barium oxide of 6. The second slurry was applied to the other end of the straight through cordierite substrate from the outlet end in a top-fed, 40Hz negative pressure suction manner, over a 2 inch length, at a dry loading weight of 10g/L, and dried and then calcined in air at 550 c to form the second zone coating as shown in fig. 2, where the sum of the lengths of the first zone coating and the second zone coating is the total length of the substrate and the first zone coating has a greater thickness than the second zone coating.
S3: adding water into an SSZ-39 molecular sieve containing 3.5 percent of Cu, stirring and dispersing for 30min, then adding 5 percent of alumina adhesive, and adding water to adjust the solid content to 28 percent to obtain slurry. And coating a third slurry on the surface of the coating of the second area from the air outlet end in a manner of feeding and 40Hz negative pressure suction, wherein the coating length is 3.5 inches, the whole coating of the second area is covered, the dry weight of the third slurry is 95g/L, and the third slurry is dried and calcined in air at 550 ℃ to form a third area coating, so that the catalyst product is obtained.
Comparative example 1:
this comparative example provides a catalyst having low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
adding water into an SSZ-39 molecular sieve with the D50 of 5-8 mu m and the Cu content of 3.2 wt%, stirring and dispersing for 30min, then adding 5% of alumina adhesive (hydrated alumina, TREO oxide content of 73.60%), adding water and adjusting to the solid content of 30% to obtain slurry. Coating the slurry on a straight-through cordierite ceramic carrier with the mesh number of 600, the wall thickness of 3.2mil, the length of 5 inches and the diameter of 12 inches in a mode of feeding at the upper feeding end and sucking at the 40Hz negative pressure at the air outlet end, drying, and calcining in air at 550 ℃ to obtain the catalyst product.
Comparative example 2:
this comparative example provides a catalyst having a low temperature of NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
adding water into a BEA molecular sieve containing 4.0% of Fe, stirring and dispersing for 30min, then adding 10% of alumina binder, and adding water to adjust the solid content to 32% to obtain slurry. The slurry was applied to a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter through-type cordierite substrate by 40Hz negative pressure suction at the upper feed and outlet end. And calcining the dried product in air at 550 ℃ to obtain the catalyst product.
Comparative example 3:
this comparative example provides a catalyst having low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: adding palladium nitrate into FER microporous molecular sieve slurry with Si/Al =25, the grain size of 800nm and the molecular sieve D50 of 5-8 μm, stirring uniformly, adding 10% of alumina adhesive, adding water to adjust the solid content to 30%, and obtaining first slurry. The first slurry was uniformly coated onto a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter straight through cordierite substrate using 40Hz negative pressure suction at the upper feed and outlet end, loaded with 35g/L dry weight, dried and calcined in air at 550 ℃ to form a first zone coating having a noble metal content of 0.45wt%.
S2: and adding water into the gamma-alumina with the particle size of 1-3 mu m for mixing to prepare alumina suspension, adding the nano barium oxide colloid suspension according to the mass ratio of the alumina to the barium oxide of 7. And uniformly coating the second slurry on the surface of the first area coating in a mode of 40Hz negative pressure suction at the upper feeding end and the air outlet end, loading 10g/L of dry weight, and calcining in air at 550 ℃ after drying to form the second area coating.
S3: adding water into a commercially available SSZ-39 molecular sieve with the D50 of 5-8 mu m and the Cu content of 3.5%, stirring and dispersing for 30min, then adding 5% of alumina adhesive, and adding water to adjust the solid content to 30% to obtain third slurry. And uniformly coating the third slurry on the surface of the coating of the second area in a mode of feeding and negative pressure suction at 40Hz of an air outlet end, loading the third slurry with the dry weight of 95g/L, drying, and calcining in air at 550 ℃ to form a third area coating, namely obtaining a catalyst product marked as catalyst No. 1.
Comparative example 4:
this comparative example provides a catalyst having a low temperature of NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: adding silver nitrate into gamma-alumina suspension with the average particle size of 100nm, uniformly stirring, adding 10% of alumina adhesive, and adding water to adjust the solid content to 28% to obtain first slurry. The first slurry was uniformly coated onto a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter straight-through cordierite substrate using 40Hz negative pressure suction at the upper feed and outlet end, and loaded with 50g/L dry weight. After drying, the coating is calcined in air at 550 ℃ to form the first zone coating.
S2: and adding water into the gamma-alumina with the particle size of 1-3 mu m for mixing to prepare alumina suspension, adding the nano barium oxide colloid suspension according to the mass ratio of the alumina to the barium oxide of 6. And uniformly coating the second slurry on the surface of the first area coating in a mode of 40Hz negative pressure suction at the upper feeding end and the air outlet end, loading 10g/L of dry weight, and calcining in air at 550 ℃ after drying to form the second area coating.
S3: the BEA molecular sieve containing 5.2wt% Fe was dispersed with water for 30min under stirring, and then 10% alumina binder was added, and water was added to adjust the solid content to 30%, to obtain a third slurry. And uniformly coating the third slurry on the surface of the coating of the second area in a manner of feeding and negative pressure suction of 40Hz at an air outlet end, loading the third slurry with a dry weight of 115g/L, drying, and calcining in air at 550 ℃ to form a third area coating, thus obtaining the catalyst product.
Comparative example 5:
this comparative example provides a catalyst having a low temperature of NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: adding cobalt oxide into SSZ-13 microporous molecular sieve slurry with Si/Al =14 and the grain size of 200nm, uniformly stirring, adding water to adjust the solid content of the slurry to 30%, and obtaining first slurry. The first slurry was uniformly coated onto a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter straight through cordierite substrate by 40Hz negative pressure suction at the upper feed and outlet end, loaded with 50g/L dry weight, dried and calcined in air at 550 ℃ to form the first zone coating.
S2: adding water into gamma-alumina with the particle size of 1-3 mu m for mixing to prepare alumina suspension, adding nano barium oxide colloid suspension according to the mass ratio of alumina to barium oxide of 6. And uniformly coating the second slurry on the surface of the first zone coating in a mode of feeding at the upper gas outlet end and sucking at 40Hz negative pressure, loading the second zone coating with a dry weight of 10g/L, drying, and calcining in air at 550 ℃ to form the second zone coating.
S3: adding water into an SSZ-39 molecular sieve containing 3.5% of Cu, stirring and dispersing for 30min, then adding 5% of alumina adhesive, and adding water to adjust the solid content to 30% to obtain third slurry. And uniformly coating the third slurry on the surface of the coating of the second area in a manner of feeding and negative pressure suction of 40Hz at an air outlet end, loading the third slurry with a dry weight of 95g/L, drying, and calcining in air at 550 ℃ to form a third area coating, thus obtaining the catalyst product.
Comparative example 6:
this comparative example provides a catalyst having low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: adding silver nitrate into SSZ-13 microporous molecular sieve slurry with Si/Al =14 and the grain size of 200nm, stirring uniformly, adding 10% of alumina adhesive, and adding water to adjust the solid content of the slurry to 30%. From the inlet end, the slurry was applied by top-feed, 40Hz negative pressure suction to a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter, straight through cordierite substrate, loaded on a dry weight of 45g/L and coated to a length of 2.5 inches, dried and calcined in air at 550 deg.C to form the first zone coating.
S2: and adding water into the gamma-alumina with the particle size of 1-3 mu m for mixing to prepare an alumina suspension, adding the nano iron oxide suspension according to the mass ratio of the alumina to the iron oxide of 3. The second slurry was applied to the other end of the flow-through cordierite substrate from the outlet end in a top-feed, 40Hz negative pressure suction manner to a coating length of 2.5 inches with an upper loading dry weight of 10g/L, dried and then calcined in air at 550 deg.C to form the second zone coating, as shown in FIG. 3, where the sum of the lengths of the first zone coating and the second zone coating was the total length of the substrate and the thicknesses of the two were the same.
S3: adding water into a BEA molecular sieve containing 5.2% of Fe, stirring and dispersing for 30min, then adding 10% of alumina adhesive, and adding water to adjust the solid content to be 30% to obtain third slurry. And coating the third slurry on the surface of the first area coating to the second area coating from the air inlet end in a manner of feeding and 40Hz negative pressure suction, wherein the coating length is 5 inches, the dry weight of the upper loading is 115g/L, and the third area coating is formed by calcining in air at 550 ℃ after drying, so that the catalyst product is obtained.
Comparative example 7:
this comparative example provides a catalyst having low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: palladium nitrate is added into FER microporous molecular sieve slurry with the grain size of 800nm and Si/Al =25, after uniform stirring, 10% of alumina adhesive is added, and water is added to adjust the solid content of the slurry to 30%. From the inlet end, the slurry was coated onto a 600 mesh, 3.2mil thick, 5 inch long, 12 inch diameter straight-through cordierite substrate by top feed, 40Hz negative pressure suction, loaded on a dry weight of 30/L and coated to a length of 3.5 inches, dried and calcined in air at 550 ℃ to form a first zone coating.
S2: adding water into gamma-alumina with the particle size of 1-3 mu m for mixing to prepare alumina suspension, adding nano iron oxide suspension according to the mass ratio of the alumina to the iron oxide of 3. The second slurry was applied to the other end of the straight through cordierite substrate from the outlet end in a top-fed, 40Hz negative pressure suction manner, over a 2 inch coating length with an upper loading dry weight of 10g/L, dried and then calcined in air at 550 c to form the second zone coating, as shown in fig. 3, where the sum of the first zone coating length and the second zone coating length was the total length of the substrate and the thicknesses were the same.
S3: adding water into an SSZ-39 molecular sieve containing 3.5% of Cu, stirring and dispersing for 30min, then adding 5% of alumina binder, and adding water to adjust the solid content to 28% to obtain third slurry. And coating the third slurry on the surface of the first area coating to the second area coating from the air inlet end in a manner of feeding and 40Hz negative pressure suction, wherein the coating length is 5 inches, the dry loading weight is 95g/L, and calcining in air at 550 ℃ after drying to form a third area coating, namely a catalyst product marked as catalyst No. 3.
After the hydrothermal aging test at 650 ℃ for 100 hours, the catalyst articles obtained in 3 examples and 7 comparative examples of the present invention were subjected to a steady-state performance test by drilling test samples having a diameter of 1 inch and a length of 5 inches, respectively. The experimental conditions are shown in Table 2. In the test process, the heating rate is set to be 6 ℃/min, the temperature is increased to 500 ℃, and the second data of the concentration of each gas-phase component at the inlet and the outlet are continuously recorded.
TABLE 2 Steady State Performance test atmosphere conditions
According to inlet NO concentration, outlet NO 2 Concentration and outlet N 2 The ratio of the sum of 2 times the O concentration minus the outlet NO concentration to the inlet NO concentration is NO X And (4) conversion rate. The following table shows the NO of the catalyst articles obtained in the examples and comparative examples X Conversion performance. Cold Start NO X The adsorption efficiency is defined as the first 200 ℃ from the start to the inlet temperature.
TABLE 3 Steady State Performance test results
As a result: comparative example 1 full length Cu-SSZ-39 catalyst comparative example 2 is a full length Fe-BEA catalyst and the advantages of comparative example 1 over comparative example 2 are mainly better low temperature zone efficiency but if under more stringent regulatory constraints, at cold start (below 200 ℃), some N remainsO X And (4) the emission is easy to exceed the standard. Therefore, further improvement of the conversion efficiency in the low temperature region is required. The advantage of comparative example 2 is mainly that the efficiency in the high temperature region (. Gtoreq.300 ℃) is better than that of the copper-based catalyst, and is not elaborated in detail in the present invention.
The third zone coatings of example 1, example 3, comparative example 5, comparative example 7 were all Cu-SSZ-39, whose main function was to convert NO released after adsorption of the first zone coating X And the second region coating the partially reduced NO. The first zone coating and the second zone coating of comparative example 3 and comparative example 5 are full coating height, while the second zone coating and the third zone coating of example 1, example 3, comparative example 7 are 30% -70% and 70% -30% respectively and different catalytic materials, since the second zone coating of comparative example 3, comparative example 5 completely covers the first zone coating, ensuring NO desorbed from the first zone coating X Sufficiently adsorbed and catalytically reduced by the second zone coating to ensure NO 2 And NO, thus the conversion efficiency of the comparative examples 3 and 5 is relatively improved. In contrast, the first zone coatings and the second zone coatings in examples 1, 3 and 7 are in "flow-through" relationship, with partially desorbed NO X NO adsorbed by the first zone coating without reduction of the second zone coating X During the release process, the second zone coating is not completely reduced, but directly enters the third zone coating for NH 3 SCR catalyzed reactions, conversion efficiency is slightly lower.
In accordance with the above examples in comparative example 4, example 2 and comparative example 6, the first zone coating and the second zone coating in the "flow-through" relationship of the partially desorbed NO's in examples 2 and 6 X NO adsorbed by the first zone coating without reduction of the second zone coating X During the release process, the second zone coating is not completely reduced, but directly enters the third zone coating for NH 3 SCR catalyzes the reaction, and therefore, the conversion efficiency is slightly lower.
Both the sulfur poisoning test and the regeneration test of the samples were performed in a fixed bed quartz reactor. N at 600 deg.C 2 Pretreating under atmosphere for 30min, then cooling the catalyst to 250 deg.C, and introducing 50ppm SO 2 、5％O 2 、10％H 2 O，N 2 As equilibrium gas, the pressure was maintained for 40min at a space velocity (GHSV) of 76000mL g cat -1 ·h -1 And finally obtaining the sulfated SCR catalyst. The catalyst regeneration desulfurization is carried out at 550 ℃ and 500ppmNH 3 、500ppmNO、10％O 2 、8％CO 2 、7％H 2 O and N 2 And (4) regenerating for 30min in the SCR atmosphere as the balance gas, wherein the space velocity is the same as the above. After the sulfur poisoning and regeneration tests were completed, steady state performance tests were performed using the simulated gas of table 2. The test procedure was as above, and NO of the catalyst was calculated X The conversion efficiency. Table 4 shows the NO of the catalyst articles X Conversion performance. Cold start NO X The adsorption efficiency is defined as the first 200 ℃ from the start to the inlet temperature.
Table 4 test results of catalyst articles provided by the present invention before and after sulfur poisoning
As shown in table 4, the first coating scheme (comparative example 3, comparative example 4, comparative example 5) used a layered design, with the first zone coating having a larger reactive interface with the second zone coating than the second and third coating schemes. And, since the second zone coating separates the first zone coating containing noble metal having oxidizing ability from the third zone coating, NO is generated from the first zone coating 2 Is effectively reduced to avoid NO 2 Escape directly with NH 3 Contact, reduce N 2 And (4) generating O. Thus, as can be seen from the steady state performance test results, the outlet maximum N of the catalyst involved in coating scheme one 2 The O concentration is much lower than coating scheme two (example 1, example 2, example 3) and coating scheme three (comparative example 6, comparative example 7).
Coating scheme two (example 1, example 2, example 3) the first zone coating is arranged at the air inlet end and directly contacts with the tail gas, so that the coating has better low-temperature adsorption. NO at test temperatures below 175 deg.C X The conversion efficiency is higher. After the temperature is higher than 200 c,the catalyst reduction layer limited by the scheme 2 has smaller contact surface and NO at the same temperature X The conversion efficiency was slightly lower.
Coating scheme three (comparative examples 6 and 7) the first zone coating was placed on the bottom layer to avoid SO 2 Is oxidized with NH 3 Or the active center in the catalyst forms stable sulfur species to cover the catalyst surface and reduce the catalytic reduction activity, so that the catalyst product has better sulfur resistance than the second coating scheme, and NO reaches the ignition temperature of the surface catalyst X The conversion efficiency was slightly higher.
While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (10)
1. Has low-temperature NO X SCR catalyst of adsorption function adopts circulation type material all in one piece substrate, its characterized in that: the catalyst product adopts a flow-through monolith substrate, a zoned coating catalyst is arranged on the substrate, the zoned coating catalyst comprises a first zone coating, a second zone coating and a third zone coating, wherein the first zone coating is tightly attached to the wall of the substrate hole and is positioned at the air inlet end of the substrate, the second zone coating is tightly attached to the wall of the substrate hole and is positioned at the air outlet end of the substrate, the sum of the lengths of the first zone coating and the second zone coating is equal to the total length of the substrate, and the third zone coating is positioned on the second zone coating and has the same length as the second zone coating; the first zone coating comprises a passive nox adsorption catalyst composition and the second zone coating comprises NO 2 Reducing the catalyst composition, the third zone coating comprising NO X Reducing the catalyst composition; the first zone coating absorbs NO in the exhaust gas at a temperature below 150 DEG C X And release NO above 250 ℃ X (ii) a Said second zone coating reacting NO X A certain proportion of NO 2 Conversion to NO 2 And NO concentration ratio of 0.8-1.2: 1; the third zone coating is to convert NO X Conversion to N 2 。
2. The method of claim 1 having low temperature NO X SCR catalyst of adsorption function, its characterized in that: passive oxynitride adsorption catalyst composition, NO 2 Reductive catalyst composition, NO X The ratio of the supported amount of the reducing catalyst composition is 30 to 50:10:95 to 120.
3. The method of claim 1 having low temperature NO X SCR catalyst of adsorption function, its characterized in that: the loading amount of the passive oxynitride adsorption catalyst composition in the first zone coating is 30-50 g/L; NO in the coating of the second zone 2 The loading of the reduced catalyst composition is 10 + -2 g/L; NO in third zone coating X The loading of the reduction catalyst composition is 95-120 g/L.
4. The method of claim 1 having low temperature NO X SCR catalyst of adsorption function, its characterized in that: the substrate is made of one of cordierite, silicon carbide and metal materials.
5. The method of claim 4 having low temperature NO X SCR catalyst of adsorption function, its characterized in that: the metal material is one of Fe-Cr-Ni alloy, co-Cr-Ni alloy and Ni-Cr-Mo alloy.
6. The method of claim 1 having low temperature NO X An SCR catalyst with an adsorption function, characterized in that: the passive oxynitride adsorption catalyst composition comprises a precious metal active component and a first adsorption refractory carrier, wherein the precious metal active component is at least one of Pd, ag and Co, and the first adsorption refractory carrier is a first molecular sieve or a metal oxide.
7. The method of claim 6 having low temperature NO X SCR catalyst of adsorption function, its characterized in that: the passive oxynitride adsorption catalyst composition further comprises a base metal or a rare earthThe base metal is at least one of Mn, co, zr and Ni, and the rare earth metal is Ce or La.
8. The method of claim 1 having low temperature NO X SCR catalyst of adsorption function, its characterized in that: said NO 2 The reducing catalyst composition comprises NO 2 Reducing the active component and a second adsorptive refractory carrier, said NO 2 The reduction active component is one or more of ferric oxide, cobalt oxide, copper oxide, barium oxide, calcium oxide, magnesium oxide, strontium oxide, tin oxide and germanium oxide, and the second adsorptive refractory carrier is silicon oxide or gamma-alumina.
9. The method of claim 1 having low temperature NO X An SCR catalyst with an adsorption function, characterized in that: said NO X The reducing catalyst composition comprises NO X Reducing the active ingredient and a third adsorptive refractory carrier, said NO X The reducing active component is one or more of Cu, mn, V, fe, co, W, ni, zn, ti, cr, Y, zr, nb and Mo, and the third adsorptive refractory carrier comprises one or symbiotic mixture of analcime, chabazite, heulandite, stilbite, erionite, mordenite, scolecite and natrolite.
10. An exhaust gas treatment device for a lean burn engine, comprising the low temperature NO treatment device of any one of claims 1 to 9 X An SCR catalyst with adsorption function.
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| CN114433202A (en) * | 2021-12-23 | 2022-05-06 | 惠州市瑞合环保科技有限公司 | Diesel engine tail gas purification SCR catalyst and coating process thereof |
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| CN105443202A (en) * | 2014-09-23 | 2016-03-30 | 福特环球技术公司 | Method of controlling NOx by PNA |
| CN107106982A (en) * | 2014-11-19 | 2017-08-29 | 庄信万丰股份有限公司 | Combination S CR and PNA is controlled for discharged at lower temperature |
| US20170001169A1 (en) * | 2015-07-02 | 2017-01-05 | Johnson Matthey Public Limited Company | PASSIVE NOx ADSORBER |
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