CN114575978A - System and method for treating gas containing nitrogen oxide - Google Patents
System and method for treating gas containing nitrogen oxide Download PDFInfo
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- CN114575978A CN114575978A CN202110190315.7A CN202110190315A CN114575978A CN 114575978 A CN114575978 A CN 114575978A CN 202110190315 A CN202110190315 A CN 202110190315A CN 114575978 A CN114575978 A CN 114575978A
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- ammonia
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 224
- 239000007789 gas Substances 0.000 title claims abstract description 144
- 238000000034 method Methods 0.000 title claims abstract description 21
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 189
- 239000003054 catalyst Substances 0.000 claims abstract description 123
- 238000010531 catalytic reduction reaction Methods 0.000 claims abstract description 93
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 78
- 238000006243 chemical reaction Methods 0.000 claims abstract description 63
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 52
- 230000003647 oxidation Effects 0.000 claims abstract description 50
- 238000002347 injection Methods 0.000 claims abstract description 37
- 239000007924 injection Substances 0.000 claims abstract description 37
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 claims abstract description 33
- 239000007787 solid Substances 0.000 claims abstract description 25
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 62
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 28
- 239000001569 carbon dioxide Substances 0.000 claims description 26
- 230000002829 reductive effect Effects 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 13
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 12
- 239000001257 hydrogen Substances 0.000 claims description 11
- 230000003197 catalytic effect Effects 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 10
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical group O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims description 9
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 8
- 238000006555 catalytic reaction Methods 0.000 claims description 7
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 6
- 238000003421 catalytic decomposition reaction Methods 0.000 claims description 6
- 229910052697 platinum Inorganic materials 0.000 claims description 4
- 239000011148 porous material Substances 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 229910052703 rhodium Inorganic materials 0.000 claims description 3
- 239000010948 rhodium Substances 0.000 claims description 3
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 22
- 239000004202 carbamide Substances 0.000 description 22
- OWIKHYCFFJSOEH-UHFFFAOYSA-N Isocyanic acid Chemical compound N=C=O OWIKHYCFFJSOEH-UHFFFAOYSA-N 0.000 description 13
- 238000001321 HNCO Methods 0.000 description 11
- 238000000197 pyrolysis Methods 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 5
- 229910000333 cerium(III) sulfate Inorganic materials 0.000 description 5
- 238000002425 crystallisation Methods 0.000 description 5
- 230000008025 crystallization Effects 0.000 description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- ZFSLODLOARCGLH-UHFFFAOYSA-N isocyanuric acid Chemical compound OC1=NC(O)=NC(O)=N1 ZFSLODLOARCGLH-UHFFFAOYSA-N 0.000 description 4
- 239000011572 manganese Substances 0.000 description 4
- VPKDCDLSJZCGKE-UHFFFAOYSA-N methanediimine Chemical compound N=C=N VPKDCDLSJZCGKE-UHFFFAOYSA-N 0.000 description 4
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 4
- 238000002791 soaking Methods 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 2
- OHJMTUPIZMNBFR-UHFFFAOYSA-N biuret Chemical compound NC(=O)NC(N)=O OHJMTUPIZMNBFR-UHFFFAOYSA-N 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002808 molecular sieve Substances 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- XLJMAIOERFSOGZ-UHFFFAOYSA-N anhydrous cyanic acid Natural products OC#N XLJMAIOERFSOGZ-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- -1 hydrogen Chemical class 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 150000002696 manganese Chemical class 0.000 description 1
- 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 description 1
- PPNAOCWZXJOHFK-UHFFFAOYSA-N manganese(2+);oxygen(2-) Chemical class [O-2].[Mn+2] PPNAOCWZXJOHFK-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- 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
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/656—Manganese, technetium or rhenium
- B01J23/6562—Manganese
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- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/008—Mounting or arrangement of exhaust sensors in or on exhaust apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
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- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
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- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
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- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
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- F01N2610/00—Adding substances to exhaust gases
- F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
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- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
- F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
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- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
- F01N2610/1486—Means to prevent the substance from freezing
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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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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Abstract
The present disclosure relates to a system and method for treating a nitrogen oxide-containing gas. The system comprises: the device comprises a gas inlet to be treated, an oxidation catalyst, a first ammonia injection assembly and a first selective catalytic reduction functional device; the device comprises a gas inlet, an oxidation catalyst, a first selective catalytic reduction functional device, a second selective catalytic reduction functional device, a gas inlet, an oxidation catalyst and a gas inlet, wherein the gas inlet, the oxidation catalyst and the first selective catalytic reduction functional device are sequentially arranged along the flow direction of a gas to be treated, and communicated gas flow channels are formed; a first catalyst is arranged in the first selective catalytic reduction functional device and is used for catalyzing nitrogen oxides to react with ammonia gas; the first catalyst comprises a carrier and manganese oxide and CeO loaded on the carrier2(ii) a The first ammonia injection assembly is arranged between the oxidation catalyst and the first selective catalytic reduction function deviceIn the gas flow passage, the ammonia injection assembly includes a first solid ammonia storage tank and a first ammonia gas nozzle. The system can treat the nitrogen oxides at a lower temperature (above 100 ℃), and has higher nitrogen oxide conversion rate.
Description
Technical Field
The present disclosure relates to the field of motor vehicle exhaust treatment, and in particular, to a system and method for treating a gas containing nitrogen oxides.
Background
By interpreting light-duty diesel vehicle (LDD) emissions regulations, an upgrade from 5(CN V) to 6b (CN VIb) NO can be foundXEmission limit decreased by 82.1%, NOXEmissions exhibit a more stringent trend.
Currently, DPF devices (Diesel Particulate traps, Diesel Particulate filters), SDPF devices (DPF with SCR Function) and SCR devices (Selective Catalytic Reduction) are widely used in the industry in a main aftertreatment arrangement treatment mode for the emission route of light Diesel vehicles to the national vi emission regulations.
The urea is injected in a common post-treatment system to provide ammonia gas to react with nitrogen oxides in tail gas, but the urea is seriously crystallized in a urea mixing cavity behind a urea nozzle and in front of an SCR or SDPF carrier; even on SCR; most commonly, in-nozzle crystallization, causes urea injection difficulties, for reasons including:
SCR or SDPF is used to purify Nitrogen Oxides (NO)X) The reactant adopted is ammonia (NH)3) Ammonia (NH)3) With Nitrogen Oxides (NO) in SCR or SDPFX) The reaction is shown in the formulas (1), (2) and (3):
2NH3+NO+NO2→2N2+3H2O(1)；
8NH3+6NO2→7N2+12H2O(2)；
4NH3+4NO+O2→4N2+6H2O(3)。
urea [ CO (NH) for vehicle2)2]Is ammonia (NH)3) The carrier of (3) has good convenience. Urea [ CO (NH) by means of urea nozzles2)2]Spraying urea [ CO (NH) in the form of liquid droplets from a urea nozzle2)2]Pyrolysis to carbon dioxide (CO) in an exhaust system2) And ammonia (NH)3). The pyrolysis process in this ideal state is as in the equation (4) (5). CO (NH)2)2The pyrolysis first produces isocyanic acid (HNCO) and ammonia (NH)3) (ii) a Isocyanic acid (HNCO) in the presence of H2Carbon dioxide (CO) generation in O environment2) And ammonia (NH)3)。
CO(NH2)2→HNCO+NH3(4)；
HNCO+H2O→NH3+CO2(5)。
In actual operation, if urea [ CO (NH) ]2)2]The pyrolysis is insufficient, and after the urea is sprayed out from the urea nozzle, under the condition of low exhaust temperature or low flow, due to the inertia of liquid drops and the slow urea hydrolysis pyrolysis speed, under the condition of low exhaust temperature or low local airflow flow speed, the urea is partially produced [ CO (NH)2)2]Form a wall wetting phenomenon, wet at the head of the urea nozzle, urea [ CO (NH)2)2]Will follow the moisture (H)2O) is rapidly evaporated, and is gradually saturated to separate out isocyanic acid (HNCO), thereby forming a necessary precondition for crystallization.
Urea [ CO (NH) ] as shown in the formulas (6) and (7)2)2]When pyrolysis is insufficient, biuret [ NH (CO) ] is formed as an intermediate product with isocyanic acid (HNCO)2(NH2)2](ii) a Biuret [ NH (CO)2(NH2)2]Reacting with isocyanic acid (HNCO) to produce cyanuric acid [ (HNCO)3]And ammonia (NH)3). Cyanuric acid [ (HNCO)3]Is "crystalline". The reaction temperature of the reaction formulae (6) and (7) is generally 160 ℃ to 190 ℃.
CO(NH2)2+HNCO→NH(CO)2(NH2)2(6)；
HNCO+NH(CO)2(NH2)2→NH3+(HNCO)3(7)。
As shown in equation (8), 3 isocyanic acids (HNCO) can directly and rapidly produce "crystalline" cyanuric acid:
3HNCO→(HNCO)3(8)。
from the original cyanuric acid [ (HNCO)3]Polymerizing until crystals grow continuously, and increasing the probability that urea is sprayed on the surfaces of the crystals; further, urea crystals accumulate continuously to form large crystals.
The problem of crystallization in the urea injection process cannot be thoroughly solved at present. The "crystallization" problem is solved, for example, with a solid ammonia solution, which is mechanistically: solid ammonia (NH)3) Ammonia (NH) in storage tank3) Direct gasification to "ammonia (NH)3) ", and then injected into the SDPF or SCR with NOXAnd (4) reacting. Therefore, the crystallization phenomenon generated in the pyrolysis process of the urea does not occur; however, in the application process, the conversion rate of the nitrogen oxides is not improved by adopting the solid ammonia injection technology, and the efficiency of the nitrogen oxides is lower.
Disclosure of Invention
The purpose of this disclosure is to provide a system and method for treating nitrogen oxide-containing gas, which can avoid the generation of bulk crystals, and can treat nitrogen oxide at a lower temperature, and has a higher nitrogen oxide conversion rate.
To achieve the above object, a first aspect of the present disclosure provides a system for treating a nitrogen oxide-containing gas, the system comprising: the device comprises a gas inlet to be treated, an oxidation catalyst, a first ammonia injection assembly and a first selective catalytic reduction functional device;
wherein, along the flow direction of the gas to be treated, the gas inlet to be treated, the oxidation catalyst and the first selective catalytic reduction functional device are sequentially arranged and form a communicated gas flow channel;
a first catalyst is arranged in the first selective catalytic reduction functional device and is used for catalyzing nitrogen oxides to react with ammonia gas; the first catalyst comprises a carrier and manganese oxide and CeO loaded on the carrier2；
The first ammonia injection assembly is arranged in a gas flow channel between the oxidation catalyst and the first selective catalytic reduction function device, and comprises a first solid ammonia storage tank and a first ammonia nozzle.
Optionally, the carrier is V2O5(ii) a Optionally, the pore size of the support is 0.4mm to 2 mm; in the first catalyst, the CeO2And said V2O5In a molar ratio of 5 to 12: 100, respectively;
optionally, the manganese oxide is MnO2(ii) a In the first catalyst, the MnO2And said V2O5In a molar ratio of5-12：100。
Optionally, the oxidation catalyst further comprises a second catalyst for catalyzing the reaction of the water vapor to the hydrogen gas; the second catalyst is at least one selected from platinum, palladium and rhodium.
Optionally, the first selective catalytic reduction function device comprises a first housing, a reaction element, and the first catalyst;
wherein the reaction element is arranged in the first shell; the shell is provided with a first gas inlet and a first gas outlet;
the reaction element comprises a second housing; a plurality of penetrating reaction channels are arranged in the second shell along the length direction of the second shell; the reaction channel has a gas inlet end and a gas outlet end; the gas inlet end is communicated with the first gas inlet, and the gas outlet end is communicated with the first gas outlet; the first catalyst is disposed within the reaction channel.
Optionally, the inner wall of the reaction channel is coated with a first catalytic coating comprising the first catalyst;
optionally, the first catalytic coating has a thickness of 1 μm to 120 μm.
Optionally, the first ammonia nozzle is arranged at the top of a gas flow channel between the oxidation catalyst and the first selective catalytic reduction function device, and the first ammonia nozzle is close to an inlet of the first selective catalytic reduction function device.
Optionally, the system further comprises a second selective catalytic reduction function device and a second solid ammonia injection assembly;
the second selective catalytic reduction function device is arranged at the downstream of the first selective catalytic reduction function device along the flow direction of the gas to be treated; the second solid ammonia injection assembly is arranged between the outlet of the first selective catalytic reduction function device and the inlet of the second selective catalytic reduction function device and is used for providing ammonia gas required by the second selective catalytic reduction function device for nitrogen oxide reaction;
optionally, the first SCR device is an SDPF device and the second SCR device is an SCR device.
In a second aspect of the present disclosure, there is provided a method for treating a nitrogen oxide gas, using the system of the first aspect of the present disclosure, comprising the steps of:
-passing a gas to be treated into the nitrogen oxide aftertreatment system via the gas to be treated inlet and into the oxidation catalyst;
-causing said first ammonia injection assembly to inject ammonia gas into said system and to form a mixed gas with the gas to be treated flowing out of said oxidation catalyst into said first scr functional device;
-contacting the mixed gas with the first catalyst under catalytic reaction conditions and reacting to form nitrogen and water and the first catalyst to be reduced.
Optionally, the method further comprises:
-bringing the gas to be treated into contact with said second catalyst in said oxidation catalyst at a catalytic decomposition temperature and reacting to form hydrogen and carbon dioxide;
the gas to be treated flowing out from the oxidation catalyst and the ammonia gas injected by the first ammonia injection assembly are made into mixed gas to enter the first selective catalytic reduction function device, and the hydrogen gas is made to contact with the first catalyst to be reduced to reduce the first catalyst to be reduced.
Optionally, the catalytic reaction temperature is 100 ℃ to 600 ℃, preferably 150 ℃ to 300 ℃;
the catalytic decomposition temperature is 150-700 ℃, and preferably 150-300 ℃.
By the technical scheme, the system for treating the gas containing the nitrogen oxides adopts the solid ammonia injection technology, so that blocky crystals can be avoided; will contain manganese oxide and CeO2The first catalyst is arranged in the first selective catalytic reduction functional device, and the manganese oxide in the first catalyst can enable nitrogen oxides and ammonia gas to react at a lower temperatureThe system processing efficiency is improved; and CeO2Can also avoid the reaction between the sulfur-containing compound and the manganese oxide, reduce the loss, and simultaneously, the CeO2The catalyst can also be reduced after reacting with the sulfur-containing compound, so that the catalytic reaction efficiency in the first selective catalytic reduction function device is further improved, and the content of nitrogen oxides in the treated gas is further reduced.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
FIG. 1 is a schematic block diagram of a system for treating a nitrogen oxide-containing gas according to one embodiment of the present disclosure;
FIG. 2 is a schematic structural diagram of a first selective catalytic reduction function device provided in accordance with an embodiment of the present disclosure;
FIG. 3 is a schematic structural diagram of a reaction element provided in one embodiment of the present disclosure;
FIG. 4 is a schematic block diagram of a system for treating a nitrogen oxide-containing gas according to one embodiment of the present disclosure.
Description of the reference numerals
1-gas inlet to be treated, 2-oxidation catalyst, 3-first selective catalytic reduction function device, 4-gas flow channel, 5-first solid ammonia storage tank, 6-first ammonia nozzle, 7-first shell, 8-reaction element, 9-second shell, 10-reaction channel, 11-first nitrogen oxide sensor, 12-second nitrogen oxide sensor, 13-first high temperature sensor, 14-second high temperature sensor, 15-third high temperature sensor, 16-second selective catalytic reduction function device, 17-second ammonia nozzle, 18-second solid ammonia storage tank
Detailed Description
The following detailed description of the embodiments of the disclosure refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
In the present disclosure, unless otherwise specified, the terms "first", "second", "third", and the like are used only for distinguishing different components and do not have actual meanings such as the order of connection before and after. In the present disclosure, the use of directional words such as "upper" and "lower" are upper and lower in the normal use state of the device, and "inner" and "outer" are in terms of the outline of the device.
The inventor of the present disclosure surprisingly found that, during the reaction of nitrogen oxide and ammonia gas, introducing manganese element (manganese oxide) into the catalyst can make the nitrogen oxide and ammonia gas react at a lower temperature (above 100 ℃), significantly reducing the reaction conditions; and manganese (Mn) is easily substituted by SO2、SO3Thereby inhibiting the catalytic action of manganese, but in the case of Ce next to manganese (Mn) or manganese oxide, Ce is preferentially associated with SO2Or SO3Reacting to prevent the manganese element or manganese oxide from being SO2Or SO3(ii) an effect; and Ce with SO2Or SO3The products of the reaction may also be reduced.
Specifically, Ce is usually represented as Ce4+Added to the first catalyst as sulfide SO2/SO3Encounter NH3、H2O and Ce4+Then, it will preferentially react with Ce4+Reaction to produce Ce2(SO4)3Avoidance of NH formation4HSO4(ii) a And Ce2(SO4)3Can be further reduced to CeO by hydrogen2And/or Ce, see the following chemical reaction formulas (9), (10):
Ce2(SO4)3+2H2→2CeO2+2H2O+3SO2(9) (ii) a Or
Ce2(SO4)3+3H2+2O2→2CeO2+3H2O+3SO3(10)。
SO3In the presence of H2Will generate SO under the atmosphere2And H2O, see formula (11) below:
SO3+H2→SO2+H2O(11)。
further, CeO2Can also be mixed with CO, hydrocarbon, H2And any one of NO and Ce is reduced.
SO2Can adopt H2Cleaning, see formula (12): SO (SO)2+3H2→H2S+2H2O (12) to further reduce the interference of sulfur-containing compounds in the system on the catalyst.
Referring to FIG. 1, a first aspect of the present disclosure provides a system for treating a nitrogen oxide-containing gas, the system comprising: the device comprises a gas inlet 1 to be treated, an oxidation catalyst 2, a first ammonia injection assembly and a first selective catalytic reduction functional device 3;
wherein, along the flow direction of the gas to be treated, the gas inlet 1 to be treated, the oxidation catalyst 2 and the first selective catalytic reduction functional device 3 are arranged in sequence and form a communicated gas flow channel 4;
a first catalyst is arranged in the first selective catalytic reduction functional device 3 and is used for catalyzing the reaction of nitrogen oxides and ammonia gas; the first catalyst comprises a carrier and manganese oxide and CeO loaded on the carrier2；
The first ammonia injection assembly is arranged in a gas flow passage 4 between the oxidation catalyst and the first selective catalytic reduction function device, and comprises a first solid ammonia storage tank 5 and a first ammonia nozzle 6.
The system for treating gas containing nitrogen oxides provided by the disclosure will comprise manganese oxides and CeO2The first catalyst is arranged in the first selective catalytic reduction functional device, and the manganese oxide can enable the nitrogen oxide and ammonia gas to react at a lower temperature, so that the conversion rate of the nitrogen oxide under a low-temperature condition is improved; and CeO2Can also avoid the reaction between sulfide and manganese oxide, reduce loss, and simultaneously, CeO2And reduction can be carried out after the reaction with the sulfide, so that the catalytic efficiency of the first catalyst is further improved.
In one embodiment, the Oxidation catalyst employed in the system for treating a gas containing nitrogen oxides is a device conventional in the art, such as a DOC (diesel Oxidation catalyst), LNT (LeanNO)Xtrap), and the like.
The term "selective catalytic reduction device" in the present disclosure refers to a device that can react nitrogen oxides with ammonia in an automobile exhaust aftertreatment system. The selective Catalytic reduction device is also conventional in the art, such as sdpf (diesel particulate Filter with SCR function), SCR (selective Catalytic reduction).
In one embodiment, the support in the first catalyst of the present disclosure is V2O5(ii) a In a preferred embodiment, the pore size of the support is between 0.4mm and 2 mm. The carrier that this disclosure adopted itself has the characteristic of adsorbing the ammonia, can adsorb fixed ammonia, avoids the ammonia to be taken out first selective catalytic reduction functional device along with the air current, improves the conversion rate of ammonia.
In a preferred embodiment, in the first catalyst, the CeO is2And said V2O5In a molar ratio of 5 to 12: 100, respectively; in a preferred embodiment, the manganese oxide is MnO2In the first catalyst, the MnO2And said V2O5In a molar ratio of 5-12: 100.
further, in the present disclosure, the cerium element may also be in the form of metal simple substance Ce, and the simple substance Ce may be oxidized into CeO under the air condition2。
In one embodiment, the support employed in the first catalyst may also be a molecular sieve which should also have the function of adsorbing ammonia gas, such as a ZSM-5 molecular sieve.
In a specific embodiment, the first catalyst is prepared by a dipping roasting method, and specifically comprises the following steps:
1) soaking the carrier into a soaking solution containing metal Ce and manganese salt, so that the soaking solution is fully and uniformly distributed on the wall surface of a pore channel of the carrier, and the soaking time is 1 minute;
2) placing the impregnated carrier into a muffle furnace for roasting, wherein the temperature in the muffle furnace is 350 ℃, and the roasting time is 8 minutes;
3) taking the roasted carrier out of the muffle furnace, and cooling the carrier in the air for 1 minute;
4) repeating the foregoing steps 1) -3) 5 times;
5) and (3) roasting the carrier obtained in the step 4) in a muffle furnace for 5 hours to enhance the firmness of coating, so as to obtain the final first catalyst. The raw materials and reagents adopted in the application are all conventionally selected in the field. For example, vector V2O5Commercially available from basf, eumeco, banker, NGK, corning.
In one embodiment, the present disclosure provides a second catalyst within the oxidation catalyst 2, wherein the second catalyst is selected from the group consisting of precious metals, and further may be selected from at least one of platinum, palladium, rhodium. In a system for treating a nitrogen oxide-containing gas, a second catalyst is provided in a device upstream of a first selective catalytic reduction function device, and hydrogen gas can be generated by water vapor for a reduction reaction of the first catalyst in the first selective catalytic reduction function device. Wherein the chemical reaction formula for generating hydrogen is as follows: h2O+CO→H2+CO2. In the present disclosure, water vapor generated by the system itself, such as water vapor generated when non-nitrogen oxides are subjected to "oxyfuel combustion", or the like, is used without introducing additional water vapor.
Referring to fig. 2 and 3, in one embodiment, the present disclosure employs a first selective catalytic reduction function device including a first housing 7, a reaction element 8, and a first catalyst;
wherein, the reaction element 8 is arranged in the first shell 7; the shell is provided with a first gas inlet and a first gas outlet;
the reaction element comprises a second housing 9; along the length direction of the second shell 9, a plurality of through reaction channels 10 are arranged in the second shell; the reaction channel is provided with a gas inlet end and a gas outlet end; the gas inlet end is communicated with the first gas inlet, and the gas outlet end is communicated with the first gas outlet; the first catalyst is disposed in the reaction channel. In a preferred embodiment, the reaction channel has an internal diameter of 0.4mm to 2 mm.
In one embodiment, the inner walls of the reaction channel 10 are coated with a first catalytic coating comprising a first catalyst;
optionally, the first catalytic coating has a thickness of 1 μm to 120 μm.
In another embodiment, manganese oxide may also be mixed with CeO2And the carrier is coated on the inner wall of the reaction channel 10 after being uniformly mixed.
In one embodiment, referring to fig. 1, a first ammonia gas nozzle 6 is provided at the top of the gas flow passage 4 between the oxidation catalyst 2 and the first selective catalytic reduction function device 3, and the first ammonia gas nozzle 6 is close to the inlet of the first selective catalytic reduction function device 3.
In one embodiment, referring to FIG. 1, the system further includes a first NOx sensor 11 and a second NOx sensor 12;
the first nitrogen oxide sensor 11 is arranged between the oxidation catalytic converter 2 and the first ammonia injection assembly, is close to the outlet of the oxidation catalytic converter 2, and is used for detecting the content of nitrogen oxides in the gas to be treated entering the first selective catalytic reduction functional device;
the second nox sensor 12 is disposed downstream of the first scr functional device 3 along the flow direction of the gas to be treated, and is configured to detect the content of nox in the gas treated by the first scr functional device, and determine the operation of the post-treatment device according to the detection result, for example, the post-treatment device further includes a second ammonia injection module and a second scr functional device, and then injects an appropriate amount of ammonia gas from the subsequent ammonia injection module according to the content of nox detected by the second nox sensor, so as to further treat nox.
In a further embodiment, the first solid ammonia injection assembly further comprises a flow control unit in signal communication with the first NOx sensor for controlling the flow of ammonia gas from the nozzle in response to a signal measured by the first NOx sensor.
In one embodiment, the system further comprises a first high temperature sensor 13, a second high temperature sensor 14 and a third high temperature sensor 15;
the first high-temperature sensor 13 is arranged between the gas inlet 1 to be treated and the inlet of the oxidation catalyst 2 of the system, and is used for monitoring the temperature of the gas to be treated entering the oxidation catalyst and preventing the system from being damaged due to overhigh temperature;
the second high-temperature sensor 14 is arranged between the first nitrogen oxide sensor 11 and the first ammonia nozzle 6, is close to the first nitrogen oxide sensor 11, and is used for monitoring the temperature of the gas to be treated entering the selective catalytic reduction functional device and preventing the system from being damaged due to overhigh temperature;
the third high temperature sensor 15 is disposed between the outlet of the first scr functional device 3 and the second nox sensor 12 and near the outlet of the first scr functional device 3, and is configured to monitor the temperature of the gas processed by the first scr functional device, so as to prevent the gas temperature from being too high during subsequent processing.
In one embodiment, the system further comprises a second selective catalytic reduction function device and a second solid ammonia injection assembly;
the second selective catalytic reduction function device 16 is arranged downstream of the first selective catalytic reduction function device 3 in the flow direction of the gas to be treated; the second solid ammonia injection assembly is arranged between the outlet of the first selective catalytic reduction function device 3 and the inlet of the second selective catalytic reduction function device 16 and used for providing ammonia gas required by the second selective catalytic reduction function device for nitrogen oxide reaction.
In one embodiment, the second selective catalytic reduction function device 16 is provided downstream of the second nitrogen oxide sensor 12 in the flow direction of the gas to be treated; the second solid ammonia injection assembly is arranged between the outlet of the second selective catalytic reduction function device 16 and the second nitrogen oxide sensor 12 and close to the second nitrogen oxide sensor 12; the second solid ammonia injection assembly includes a second ammonia gas nozzle 17 and a second solid ammonia storage tank 18.
In a preferred embodiment, the second selective catalytic reduction function device is also provided with a first catalyst to further improve the efficiency of treating nitrogen oxides.
In one embodiment, the first selective catalytic reduction Function device is a Diesel particulate trap with SCR Function (SDPF); the second Selective Catalytic Reduction function device is a Selective Catalytic Reduction (SCR) device.
In one embodiment, the system provided by the present disclosure may further include lean-burn nitrogen oxides NOXThe trapping device LNT may be disposed upstream of the oxidation catalyst 2 along a flow direction of the gas to be treated, and further, a second catalyst may be disposed in the LNT, so that more hydrogen may be generated to reduce Ce element of the first catalyst in the selective catalytic reduction device.
The first selective catalytic reduction function device and the second selective catalytic reduction function device employed in the present disclosure are all devices conventionally selected in the art.
A second aspect of the present disclosure provides a method of treating a nitrogen oxide gas using the nitrogen oxide aftertreatment system provided by the first aspect of the present disclosure, the method comprising the steps of:
-passing the gas to be treated into the nitrogen oxide aftertreatment system via the gas to be treated inlet and into the oxidation catalyst 2;
-making the first ammonia injection component inject ammonia gas into the system and form a mixed gas with the gas to be treated flowing out of the oxidation catalyst 2 into the first selective catalytic reduction function device 3;
under the condition of catalytic reaction, the mixed gas contacts with the first catalyst and reacts to generate nitrogen and water and the first catalyst to be reduced.
In one embodiment, the method further comprises:
-bringing the gas to be treated into contact with a second catalyst in the oxidation catalyst 2 at a catalytic decomposition temperature and reacting to form hydrogen and carbon dioxide;
the gas to be treated flowing out through the oxidation catalyst 2 and the ammonia gas injected by the first ammonia injection assembly are made to form a mixed gas, and the mixed gas enters the first selective catalytic reduction functional device 3, so that the hydrogen gas contacts with the first catalyst to be reduced, and the first catalyst to be reduced is reduced.
In a preferred embodiment, the catalytic reaction temperature is from 100 ℃ to 600 ℃, preferably from 150 ℃ to 300 ℃;
the catalytic decomposition temperature is 150-700 ℃, and preferably 150-300 ℃.
Referring to FIGS. 1-4, in one embodiment, the present disclosure provides a system for treating a nitrogen oxide-containing gas, the system comprising:
a gas inlet 1 to be treated, an oxidation catalyst 2, a first ammonia injection assembly, and a first selective catalytic reduction function device (SDPF) 3;
wherein, along the flow direction of the gas to be treated, the gas inlet 1 to be treated, the oxidation catalyst 2 and the first selective catalytic reduction function device (SDPF)3 are arranged in sequence and form a communicated gas flow channel 4;
a first catalyst is arranged in the first selective catalytic reduction functional device (SDPF)3 and is used for catalyzing nitrogen oxides to react with ammonia gas; the first catalyst comprises V2O5And the load is at V2O5MnO of2And CeO2(ii) a In the first catalyst, CeO2And V2O5In a molar ratio of 8: 100, MnO2And V2O5In a molar ratio of 10: 100, respectively;
a first ammonia injection assembly is provided in the gas flow channel 4 between the oxidation catalyst 2 and the first selective catalytic reduction function device (SDPF)3, the first ammonia injection assembly comprising a first solid ammonia storage tank 5 and a first ammonia gas nozzle 6.
Wherein, the first ammonia nozzle 6 is arranged at the top of the gas flow passage 4 between the oxidation catalyst 2 and the first selective catalytic reduction function device (SDPF)3, and the first ammonia nozzle 6 is close to the inlet of the first selective catalytic reduction function device (SDPF) 3.
Wherein the first selective catalytic reduction function device (SDPF) comprises a first housing 7, a reaction element 8, and a first catalyst; the reaction element 8 is arranged in the first shell 7; the shell is provided with a first gas inlet and a first gas outlet;
the reaction element comprises a second housing 9; along the length direction of the second shell 9, a plurality of through reaction channels 10 are arranged in the second shell; the reaction channel is provided with a gas inlet end and a gas outlet end; the gas inlet end is communicated with the first gas inlet, and the gas outlet end is communicated with the first gas outlet; the first catalyst is arranged in the reaction channel; specifically, in the present embodiment, the first catalyst is coated on the inner wall of the reaction channel in the form of a coating layer having a thickness of 10 μm.
The oxidation catalyst 2 further comprises a second catalyst for catalyzing water vapor to generate hydrogen, and the second catalyst is platinum.
Wherein the system further comprises a first nox sensor 11 and a second nox sensor 12;
the first nitrogen oxide sensor 11 is arranged between the oxidation catalyst 2 and the ammonia injection assembly and is close to the outlet of the oxidation catalyst 2;
the second nox sensor 12 is provided downstream of the first selective catalytic reduction function device (SDPF)3 in the flow direction of the gas to be treated.
Further, the system also includes a first high temperature sensor 13, a second high temperature sensor 14, and a third high temperature sensor 15;
wherein, the first high temperature sensor 13 is arranged between the inlet 1 of the gas to be treated and the inlet of the oxidation catalyst 2 of the system;
the second high temperature sensor 14 is arranged between the first nitrogen oxide sensor 11 and the first selective catalytic reduction function device (SDPF)3, and is close to the first nitrogen oxide sensor 11;
the third high temperature sensor 15 is provided between the outlet of the first selective catalytic reduction function device (SDPF)3 and the second nitrogen oxide sensor 12 and near the first selective catalytic reduction function device (SDPF) 3.
Further, the system also includes a second selective catalytic reduction function device (SCR)16 and a second solid ammonia injection assembly, wherein the second solid ammonia injector includes a second ammonia nozzle 17 and a second solid ammonia storage tank 18;
a second selective catalytic reduction function device (SCR) is arranged at the downstream of the second nitrogen oxide sensor along the flow direction of the gas to be treated; the second solid ammonia injector is arranged between the outlet of the second Selective Catalytic Reduction (SCR) function device and the second nitrogen oxide sensor and close to the second nitrogen oxide sensor; specifically, the first catalyst is also provided in the second selective catalytic reduction function device.
The method for treating the nitrogen oxide gas by adopting the system provided by the embodiment comprises the following specific processes:
starting the vehicle, and ensuring that the temperature in the vehicle system is low (lower than 300 ℃):
the gas to be treated enters the system through the gas inlet to be treated, the gas to be treated firstly enters the oxidation catalyst 2, and the oxidation catalyst 2 converts Hydrocarbon (HC) carbon monoxide (CO) in the tail gas and soluble organic substances and carbon Particulate Matters (PM) in the Particulate Matters (PM) into harmless water vapor (H) through oxidation reaction2O) and carbon dioxide (CO)2) The treated gas enters a gas flow passage 4; the first nitrogen oxide sensor 11 is used for detecting the amount of nitrogen oxides in gas in the gas flow channel, the first ammonia nozzle 6 of the first ammonia injection assembly injects ammonia into the gas flow channel according to the detection result of the first nitrogen oxide sensor 11, the ammonia and the gas in the gas flow channel form mixed gas and enter the first selective catalytic reduction functional device 3 together, the mixed gas enters the reaction channel 10 of the first selective catalytic reduction functional device 3 and contacts with a first catalyst on the inner wall of the reaction channel 10 to react, wherein the ammonia and the nitrogen oxides generate ammonia and water, and sulfide and CeO mixed with the mixed gas2Reaction to form Ce2(SO4)3(ii) a The temperature in the system is low in the process, and the first selective catalytic reduction functional device provided by the disclosure can catalyze the reaction of nitrogen oxides and ammonia gas at the temperature of more than 100 ℃, so that the reaction is improvedThe efficiency is improved, and meanwhile, the pressure of a pretreatment system (such as an LNT) for adsorbing and storing nitrogen oxides is reduced when a vehicle system is at a low temperature, and the energy consumption is reduced.
When the temperature in the system gradually rises along with the running of the vehicle and reaches a medium-high temperature (such as 300 ℃), the second catalyst in the oxidation catalyst 2 can catalyze the reaction of the water vapor and the carbon monoxide to generate hydrogen, and the hydrogen can react with the Ce in the first catalyst in the reaction channel 10 after entering the first selective catalytic reduction functional device 3 along with the gas to be treated2(SO4)3Reducing to achieve self-cleaning effect, and simultaneously, the hydrogen can also be used for doping SO in the mixed gas3And SO2And reducing to reduce the interference of the sulfide on the first catalyst and improve the treatment efficiency of the system.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.
Claims (10)
1. A system for treating a gas comprising nitrogen oxides, the system comprising: the device comprises a gas inlet (1) to be treated, an oxidation catalyst (2), a first ammonia injection assembly and a first selective catalytic reduction function device (3);
wherein, along the flow direction of the gas to be treated, the gas inlet (1) to be treated, the oxidation catalyst (2) and the first selective catalytic reduction function device (3) are arranged in sequence and form a communicated gas flow channel (4);
a first catalyst is arranged in the first selective catalytic reduction functional device (3) and is used for catalyzing nitrogen oxides to react with ammonia gas; the first catalyst comprises a carrier and manganese oxide and CeO loaded on the carrier2；
The first ammonia injection assembly is arranged in a gas flow channel (4) between the oxidation catalyst (2) and the first selective catalytic reduction function device, and comprises a first solid ammonia storage tank (5) and a first ammonia gas nozzle (6).
2. The system of claim 1, wherein the carrier is V2O5(ii) a Optionally, the pore size of the support is 0.4mm to 2 mm; in the first catalyst, the CeO2And said V2O5In a molar ratio of 5 to 12: 100, respectively;
optionally, the manganese oxide is MnO2(ii) a In the first catalyst, the MnO2And said V2O5In a molar ratio of 5 to 12: 100.
3. a system according to claim 1 or 2, characterized in that the oxidation catalyst (2) further comprises a second catalyst for catalyzing the reaction of water vapour to hydrogen; the second catalyst is at least one selected from platinum, palladium and rhodium.
4. The system of claim 1, wherein the first selective catalytic reduction function device comprises a first housing (7), a reaction element (8), and the first catalyst;
wherein the reaction element (8) is arranged in the first housing (7); the shell is provided with a first gas inlet and a first gas outlet;
the reaction element comprises a second housing (9); a plurality of reaction channels (10) which penetrate through the second shell are arranged in the second shell along the length direction of the second shell (9); the reaction channel (10) has a gas inlet end and a gas outlet end; the gas inlet end is communicated with the first gas inlet, and the gas outlet end is communicated with the first gas outlet; the first catalyst is disposed within the reaction channel (10).
5. A system according to claim 4, wherein the inner walls of the reaction channel (10) are coated with a first catalytic coating comprising the first catalyst;
optionally, the first catalytic coating has a thickness of 1 μm to 120 μm.
6. The system according to claim 1, characterized in that the first ammonia nozzle (6) is arranged at the top of the gas flow channel (4) between the oxidation catalyst (2) and the first selective catalytic reduction function device (3), and the first ammonia nozzle (6) is close to the inlet of the first selective catalytic reduction function device (3).
7. The system of claim 1, further comprising a second selective catalytic reduction function device (16) and a second solid ammonia injection assembly;
the second selective catalytic reduction function device (16) is arranged at the downstream of the first selective catalytic reduction function device (3) along the flow direction of the gas to be treated; the second solid ammonia injection assembly is arranged between the outlet of the first selective catalytic reduction function device (3) and the inlet of the second selective catalytic reduction function device and is used for providing ammonia gas required by the second selective catalytic reduction function device for nitrogen oxide reaction;
optionally, the first SCR device is an SDPF device and the second SCR device is an SCR device.
8. A method for treating a nitrogen oxide gas, using the system of any one of claims 1-7, comprising the steps of:
-passing a gas to be treated into the nitrogen oxide aftertreatment system via the gas to be treated inlet and into the oxidation catalyst (2);
-causing said first ammonia injection assembly to inject ammonia gas into said system and to form a mixed gas with the gas to be treated flowing out of said oxidation catalyst (2) into said first selective catalytic reduction function device (3);
-contacting the mixed gas with the first catalyst under catalytic reaction conditions and reacting to form nitrogen and water and the first catalyst to be reduced.
9. The method of claim 8, further comprising:
-bringing the gas to be treated into contact with said second catalyst in said oxidation catalyst (2) at a catalytic decomposition temperature and reacting to form hydrogen and carbon dioxide;
-making the gas to be treated flowing out from the oxidation catalyst (2) and the ammonia gas injected from the first ammonia injection assembly form a mixed gas to enter the first selective catalytic reduction function device (3), and bringing the hydrogen gas into contact with the first catalyst to be reduced to reduce the first catalyst to be reduced.
10. The process according to claim 9, characterized in that the catalytic reaction temperature is between 100 ℃ and 600 ℃, preferably between 150 ℃ and 300 ℃;
the catalytic decomposition temperature is 150-700 ℃, and preferably 150-300 ℃.
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Application publication date: 20220603 |