CN108927149A - It is a kind of to match the LNT catalyst used and preparation method with SCR - Google Patents
It is a kind of to match the LNT catalyst used and preparation method with SCR Download PDFInfo
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- CN108927149A CN108927149A CN201810819579.2A CN201810819579A CN108927149A CN 108927149 A CN108927149 A CN 108927149A CN 201810819579 A CN201810819579 A CN 201810819579A CN 108927149 A CN108927149 A CN 108927149A
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- oxide
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- 239000003054 catalyst Substances 0.000 title claims abstract description 80
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 70
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910052751 metal Inorganic materials 0.000 claims abstract description 32
- 239000010970 precious metal Substances 0.000 claims abstract description 24
- 239000010410 layer Substances 0.000 claims abstract description 17
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 14
- 239000011248 coating agent Substances 0.000 claims abstract description 13
- 238000000576 coating method Methods 0.000 claims abstract description 13
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 8
- 239000002344 surface layer Substances 0.000 claims abstract description 7
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 60
- 239000002243 precursor Substances 0.000 claims description 37
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 35
- 229910044991 metal oxide Inorganic materials 0.000 claims description 33
- 150000004706 metal oxides Chemical class 0.000 claims description 33
- 239000002184 metal Substances 0.000 claims description 30
- 239000011777 magnesium Substances 0.000 claims description 29
- 239000007767 bonding agent Substances 0.000 claims description 28
- 239000002002 slurry Substances 0.000 claims description 28
- 239000006193 liquid solution Substances 0.000 claims description 27
- 239000010948 rhodium Substances 0.000 claims description 27
- -1 cerium zirconium aluminum Chemical compound 0.000 claims description 26
- 229910052749 magnesium Inorganic materials 0.000 claims description 21
- 229910052596 spinel Inorganic materials 0.000 claims description 17
- 239000011029 spinel Substances 0.000 claims description 17
- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Chemical compound [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 14
- RCFVMJKOEJFGTM-UHFFFAOYSA-N cerium zirconium Chemical compound [Zr].[Ce] RCFVMJKOEJFGTM-UHFFFAOYSA-N 0.000 claims description 14
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 14
- NWAHZABTSDUXMJ-UHFFFAOYSA-N platinum(2+);dinitrate Chemical group [Pt+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O NWAHZABTSDUXMJ-UHFFFAOYSA-N 0.000 claims description 14
- 238000000498 ball milling Methods 0.000 claims description 13
- 239000012266 salt solution Substances 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 11
- 239000002131 composite material Substances 0.000 claims description 10
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 claims description 10
- 150000003839 salts Chemical class 0.000 claims description 10
- 238000005470 impregnation Methods 0.000 claims description 9
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 239000011572 manganese Substances 0.000 claims description 8
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 8
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 claims description 8
- 229910052684 Cerium Inorganic materials 0.000 claims description 6
- 229910052783 alkali metal Inorganic materials 0.000 claims description 6
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 claims description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 claims description 6
- GTEJAEKKYCZWHX-UHFFFAOYSA-N [O--].[O--].[O--].[O--].[O--].[Al+3].[Zr+4].[Ce+3] Chemical compound [O--].[O--].[O--].[O--].[O--].[Al+3].[Zr+4].[Ce+3] GTEJAEKKYCZWHX-UHFFFAOYSA-N 0.000 claims description 5
- 150000001340 alkali metals Chemical class 0.000 claims description 5
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 5
- 150000002910 rare earth metals Chemical class 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 4
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 3
- 239000010931 gold Substances 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- 229910002651 NO3 Inorganic materials 0.000 claims description 2
- 150000001412 amines Chemical class 0.000 claims description 2
- ITHZDDVSAWDQPZ-UHFFFAOYSA-L barium acetate Chemical group [Ba+2].CC([O-])=O.CC([O-])=O ITHZDDVSAWDQPZ-UHFFFAOYSA-L 0.000 claims description 2
- 235000010333 potassium nitrate Nutrition 0.000 claims description 2
- 239000004323 potassium nitrate Substances 0.000 claims description 2
- AQBOUNVXZQRXNP-UHFFFAOYSA-L azane;dichloropalladium Chemical compound N.N.N.N.Cl[Pd]Cl AQBOUNVXZQRXNP-UHFFFAOYSA-L 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 9
- 239000000203 mixture Substances 0.000 abstract description 7
- 239000012752 auxiliary agent Substances 0.000 abstract description 5
- 238000013461 design Methods 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 238000005457 optimization Methods 0.000 abstract description 2
- 230000009466 transformation Effects 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 32
- 238000006722 reduction reaction Methods 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 15
- 230000009467 reduction Effects 0.000 description 15
- 229910052878 cordierite Inorganic materials 0.000 description 14
- 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 description 14
- 239000007789 gas Substances 0.000 description 14
- 229910052782 aluminium Inorganic materials 0.000 description 13
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 13
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 12
- 229910052788 barium Inorganic materials 0.000 description 10
- 238000003860 storage Methods 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 8
- 239000004202 carbamide Substances 0.000 description 7
- XSQUKJJJFZCRTK-UHFFFAOYSA-N urea group Chemical group NC(=O)N XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 7
- 206010013786 Dry skin Diseases 0.000 description 6
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 6
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 6
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 238000001833 catalytic reforming Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 4
- 150000001342 alkaline earth metals Chemical class 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 238000006555 catalytic reaction Methods 0.000 description 4
- 239000000446 fuel Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000012805 post-processing Methods 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 238000011144 upstream manufacturing Methods 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229910004625 Ce—Zr Inorganic materials 0.000 description 1
- 229910013722 M(NO3)2 Inorganic materials 0.000 description 1
- 229910001051 Magnalium Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910021543 Nickel dioxide Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000012876 carrier material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000011944 chemoselective reduction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Inorganic materials O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N nitrate group Chemical group [N+](=O)([O-])[O-] NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 238000010943 off-gassing Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000006057 reforming reaction Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000009938 salting Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000013517 stratification Methods 0.000 description 1
- AGGKEGLBGGJEBZ-UHFFFAOYSA-N tetramethylenedisulfotetramine Chemical compound C1N(S2(=O)=O)CN3S(=O)(=O)N1CN2C3 AGGKEGLBGGJEBZ-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/46—Ruthenium, rhodium, osmium or iridium
- B01J23/464—Rhodium
-
- 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
- B01D53/9422—Processes characterised by a specific catalyst for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
-
- 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
- B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
- B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/8986—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with manganese, technetium or rhenium
-
- 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
-
- B01J35/30—
-
- 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
- B01D2258/012—Diesel engines and lean burn gasoline engines
Abstract
The present invention relates to a kind of LNT catalyst for matching and using with SCR, the LNT includes noble metal, and the noble metal is including but not limited to one or more of precious metal elements such as Pt, Pd, Rh；The noble metal includes at least Rh；The LNT catalyst has layered structure, and surface layer Rh concentration is greater than the Rh concentration of internal layer.The present invention is by the optimization design of auxiliary agent, noble metal and material composition, and addition promotes HC reformation to generate H in the coating2Function to improve the NH of LNT3Production rate, the NH of generation3It is stored in the SCR in downstream, the transformation in planta rate for improving NOx is reacted with the NOx of escape.Preparation method of the present invention is simple, and step is easily operated, at low cost.
Description
Technical field
It is especially a kind of that LNT (the Lean NOx used is matched with SCR the present invention relates to a kind of auto-exhaust catalyst
Trap, lean-burn NOx trap) catalyst, the present invention also discloses the preparation methods of the LNT catalyst, belong to vehicle exhaust
Catalyst technical field.
Background technique
In diesel automobile exhaust, oxynitrides (NOx) is one of main component of tail gas.Traditional technology route is to adopt
With selective reduction catalyst (SCR) in reducing agent NH3NOx is reduced to N under effect2, NH herein3From the decomposition of urea.
Fig. 1 is row's temperature curve of certain diesel engine WHTC circulation, in WHTC test loop, only 150 DEG C of low-speed section mean temperature,
According to conventional urea SCR technology route, in low-speed section since temperature is too low, urea can not be decomposed and easily be crystallized, can not
The row of NOx when spraying urea, and then NOx can not be effectively treated, therefore new post-processing technology route need to be introduced to solve low temperature
Put problem.
The beginning of this century, European countries develop LNT and part for market, which can be at lean burn (Lean)
NOx is trapped, NOx is discharged at fuel-rich state (Rich) and is restored, 200-500 DEG C of operating temperature range.
Britain village letter ten thousand is rich to have been proposed LNT+SCR integrated system in SAE 2010-01-0302, and system LNT exists
The NH of generation is restored under fuel-rich state3Reduction when can store in the SCR in downstream, and being reacted as SCR catalyst with NOx
Agent can handle the NOx to escape from upstream in the SCR in downstream in this way, and does not have to again additional increase before SCR catalyst and urinate
Plain tank is as NH3Source.
As motor vehicle exhaust emission requires to be increasingly stringenter, existing conventional urea SCR post-processing technology route is to low temperature
NOx processing capacity is limited, and especially for 3.0L diesel car engine below, row's temperature is lower, is using existing SCR technology
It will appear the case where urea crystals can not work in route, and after-treatment device installation space is limited, therefore be directed to the type
Engine cannot reuse conventional urea SCR technology route.Can use for the post-processing of the type diesel car engine can produce
Raw NH3NH of the LNT as SCR3The minimum operating temperature in source, such LNT can be down to 150 DEG C hereinafter, in such LNT and SCR
Matching use can solve low temperature NOx emission problem.
Patent US6607704 describes important function of the magnesium aluminate spinel in LNT, and the LNT containing magnesium aluminate spinel has
Higher durability.
Village letter has studied hydrogen-storing material and precious metal ratios to NH in SAE 2010-01-03023The influence of production quantity,
Oxygen storage capacity is low, and the low Pd catalyst of high Pt has better NH3Generative capacity.
Although there is the application of many literature research LNT, how specifically to improve low-speed section exhaust temperature about LNT
It spends in low situation, the purification elimination efficiency of NOx is promoted, and still belongs to the problem that this field needs to further investigate.
Summary of the invention
It is an object of the invention to overcome in the prior art diesel engine it is too low in low-speed section delivery temperature, cause to urinate
Element injection failure, can not effectively in cleaning of off-gas NOx deficiency, a kind of LNT catalyst for matching and using with SCR is provided.
In order to achieve the above-mentioned object of the invention, the present invention provides following technical schemes:
It is a kind of to match the LNT catalyst used with SCR, the LNT catalyst include noble metal Rh and precious metals pt,
At least one of Pd.
The LNT catalyst has layered structure, and surface layer Rh concentration is greater than the Rh concentration of internal layer.
By the different precious metal concentrations between the ectonexine of optimization design LNT catalyst, so that LNT generates H2Ability increases
Add, to improve NH3Generative capacity can more preferably match use, tail gas in the case that improvement delivery temperature is too low with downstream SCR
Middle NOx detergent power.The NH that the especially SCR of the downstream LNT is generated in LNT3Reduction under may be implemented to escape
NOx is handled again, is greatly improved system to the purification efficiency of NOx.
Preferably, in LNT catalyst, internal layer Rh concentration can be 0.I.e. internal layer is free of Rh, only on the surface layer of catalyst
Containing Rh, surface layer Rh plays the central role of LNT catalyst, enhances catalyzed conversion and NH for NOx3Nucleus formation.
Further, the noble metal includes Pt；The surface layer the LNT Pt concentration is less than internal layer Pt concentration.
After LNT post-processing technology route is suitable for lean-burn (Lean) engine and is aided with fuel-rich (Rich) with reducing/regenerating
The LNT catalyst of reason, LNT catalyst aoxidizes under the Lean state of normal work and NOx adsorption, discharges simultaneously under Rich state
Reduction NOx is N2And NH3, HC, CO that simultaneous oxidation is discharged because fuel-rich.Pt concentration is most important for the catalytic action of internal layer,
Catalytic action is selectively promoted with strong.
Further, the noble metal catalyst further includes metal oxide, noble metal, alkalinous metal, Ni, Mn element.
Preferably, the noble metal is including but not limited to one or more of precious metal elements such as Pt, Pd, Rh, preferably
Ground includes at least Rh.Wherein Pd is the precious metal element that may include.
Preferably, the metal oxide is including but not limited to aluminium oxide, cerium zirconium compound oxide, cerium zirconium aluminum composite oxide
One or more of metal oxides such as object, sial composite oxides, magnesium aluminate spinel.
Preferably, the alkalinous metal refers to one kind or several of alkali metal and/or alkaline-earth metal and/or rare earth alkaline element
Kind.
Preferably, rare earth alkaline element can be cerium.
Provided by the invention that the LNT used is matched with SCR, which is mainly with metal oxide and noble metal
Basis, is subject to adsorption capacity and endurance that alkalinous metal improves it to NOx, and the elements such as addition Ni, Mn increase LNT to HC's
It reforms and produces H2Ability.Meanwhile the reasonable selection for applying layout layer, noble metal distribution and coating material of cooperation, so that LNT catalyst
Core effect significantly strengthened promotion.It is final preferably to realize that plurality of raw materials ingredient cooperates, promote to realize HC weight
Whole or water gas reaction generation is allowed to generate a large amount of H2, and promote H2It is reacted with NO and generates NH3, and improve NH3Production rate.
Specifically, to the oxygen of NO under the conditions of the LNT of the method for the present invention preparation, the Lean having in addition to traditional LNT
Change and storage, it is outer to the release of NOx and reduction under the conditions of Rich, it further include that NOx is reduced to N under the conditions of Rich2And NH3, and will
NH3It is stored in the SCR in downstream, for being reacted with the NOx to escape from upstream, the discharge of NOx is reduced to minimum.
LNT generates NH under Rich state3, it is stored in the SCR in downstream, when there is NOx to escape from the LNT of upstream, NOx
Just in the SCR in downstream with the NH of storage3Chemoselective reduction occurs and generates N2.So LNT prepared by the present invention is simultaneous simultaneously
Has higher NH3Generative capacity and higher NOx removal ability.
Further, the LNT catalyst has coating structure, and LNT catalyst coating includes metal oxide, magnalium point crystalline substance
Stone, noble metal, alkaline element and auxiliary agent.
Preferably, main group of the LNT coating becomes aluminium oxide, cerium zirconium compound oxide, magnesium aluminate spinel, cerium zirconium aluminium
Oxide, cerium oxide alkaline element similar with Ba.For example, Ba class alkaline element can be Mg as an alternative,
Ba, Mg mixture.
Further, the alkalinous metal refers to one or more of alkali metal, alkaline-earth metal and rare earth alkaline element.Institute
Stating rare earth alkaline element is cerium.
Preferably, the alkalinous metal is one or more of elements such as Ba, Mg, Ce, Sr, K, Na.
It is highly preferred that the alkalinous metal is one or more of Ba, Mg, Ce.
Further, noble metal described in the LNT includes at least Pt and Rh.
Further, LNT catalyst is supported on carrier, and the coated weight of coating is 120-400g/L.
Preferably, in LNT catalyst, the coated weight of noble metal is 20-120g/ft3。
It is a further object of the present invention to provide a kind of methods for preparing above-mentioned LNT catalyst material, pass through preparation process's
Adjusting and optimizing controls the various mutual mating reactions of material composition in LNT catalyst, and optimizes and revises catalyst layering knot
The distribution of precious metal element in structure realizes higher efficiency, realizes the effect of high catalytic conversion efficiency and reduction purification NOx.
A kind of above-mentioned method for preparing catalyst, comprising the following steps:
(1) the first soluble metal salt solution is impregnated on the first metal oxide, in terms of metal oxide, accounting is
0-20%, then 60-120 DEG C of dry 2-12h roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains alkaline material
Expect W0.
Second soluble metal salt solution is impregnated into the second metal oxide, in terms of metal oxide, accounting 0-
20%, then 60-120 DEG C of dry 2-12h roasts 2-8h in air atmosphere, obtains basic matterial at a temperature of 350-650 DEG C
WN。
(2) the first noble metal precursor liquid solution is impregnated into WN, in terms of precious metal simple substance, accounting 0.1-5%, then
60-120 DEG C of dry 2-12h roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains noble metal catalyst W1.
Second noble metal precursor liquid solution is impregnated into W0, in terms of precious metal simple substance, accounting 0.1-5%, then 60-
120 DEG C of dry 2-12h, roast 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtain noble metal catalyst W2.
Third noble metal precursor liquid solution is impregnated into third metal oxide, then 60-120 DEG C of dry 2-12h,
2-8h is roasted at a temperature of 350-650 DEG C in air atmosphere, obtains noble metal catalyst W3.
(3) W1, W2, W3 and first bonding agents are mixed, ball milling slurrying, W1 accounting 5~50%, W2 accounting 5~50%, W3
Accounting 0~30%, first bonding agents accounting 1-10%, slurry solid content are controlled in 25-50%, slurry granularity D50Control 2 μm-
10 μm, obtain Precious Metal N1.
(4) W2, W3 and second bonding agents are mixed, ball milling slurrying, W2 accounting 0~50%, W3 accounting 40-99%, second
Bonding agent accounting 1-10%, slurry solid content are controlled in 25-50%, slurry granularity D50Control obtains noble metal at 2 μm -10 μm
Slurry N2.
(5) slurry N1 is coated on carrier bottom, carrying capacity 100-300g/L, bullion content 5-120g/ft on coating3,
Dry 2-12h, then roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains catalyst at a temperature of 60-120 DEG C
C0。
(6) slurry N2 is coated on 0 upper layer of support C, carrying capacity 0-300g/L, bullion content 5-120g/ft3 on coating,
Dry 2-12h, then roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains catalyst at a temperature of 60-120 DEG C
C。
Method for preparing catalyst of the present invention is according to traditional auto-exhaust catalyst preparation process, in conjunction with catalyst of the present invention
The sequence of the design characteristics adjustment cooperation raw material application cooperation of material, is first loaded to metal oxidation for active component and alkalinous metal
On object, last slurrying is coated to carrier, sufficiently adjusts the mutual matching relationship of various material compositions, so that catalyst is living
Property maximize, achieve the effect that NOx trap, the catalysis, conversion of expected design.Inventive method simple process, easy to operate, cost
It is low, the high-quality production and processing of above-mentioned LNT catalyst product easy to accomplish.
In method for preparing catalyst of the present invention, by Ni, Mn Elemental redistribution in cerium zirconium compound oxide, aluminium oxide, cerium zirconium aluminium
In oxide, cerium oxide and supporting Pt/Pd is denoted as W1.W1 has promotes HC to reform and water gas reaction generation under Rich state
H2, while W1 is also equipped with and NO is oxidized to NO under Lean state2Ability.Alkalinous metal is distributed in aluminium oxide/sial/magnesium
In the oxides such as aluminate/cerium oxide and supporting Pt/Pd is denoted as W2.It is NO that W2, which not only has oxidation NO,2Ability, and also
The ability for having storage NOx.Rh is distributed in cerium zirconium compound oxide, aluminium oxide, cerium zirconium aluminum oxide, in cerium oxide, is denoted as W3.
W3, which has, is reduced to N for NOx2Or selective reduction is NH3Ability.W1, W2, W3 are finally combined with each other composition with prominent
The compound LNT catalyst product of catalyst effect/effect out.
Further, the carrier is including but not limited to one or more of cordierite, the pass-through type carrier of metal material.
It can also be other common carrier materials.
Compared with prior art, beneficial effects of the present invention:
(1) present invention is by design precious metal ratios, the ratio of catalysis material composition and addition Reforming catalyst element to mention
High HC reforming reaction and water gas reaction simultaneously generate H2。
(2) catalytic reforming catalyst is distributed in the bottom of coating by the present invention, reforms the H of generation2Overflow is abundant to upper layer
It is contacted with reduction zone, improves H2Utilization rate, generate suitable NH3。
(3) alkaline metal oxides such as alkaline-earth metal and magnesium aluminate spinel, cerium oxide are used in conjunction in the present invention, significantly
Improve the storage capacity of NOx.
(4) NOX oxidation and storage and distribution make NOx sufficiently and coating layer touch in bottom or upper layer in the present invention, improve NOx
Storage capacity.
(5) present invention uses traditional incipient impregnation technique and pulping process, and simple process is feasible, at low cost.
Detailed description of the invention:
Fig. 1 is row's temperature curve of certain diesel engine WHTC circulation.
Fig. 2 is catalytic reforming layer and reduction zone principle of stratification schematic diagram.
Fig. 3 is that catalytic reforming layer and reduction zone come into full contact with mixing principle schematic diagram.
Fig. 4 is the C1-C6 catalyst NOx conversion rate comparison of example 1-6 preparation.
Fig. 5 is the C1-C6 catalyst n H of example 1-6 preparation3Conversion ratio comparison.
Specific embodiment
The present invention mainly utilizes catalysis characteristics of the Pt in low cerium oxide, and HC is catalyzed under the conditions of Rich and is reformed and water coal
Solid/liquid/gas reactions generate H2, and make H2Overflow, which is reacted to reduction activation position with NO, generates NH3.Catalytic reforming coating is distributed in the present invention
In bottom, reduction zone is distributed in upper layer, the H of generation2Overflow is sufficiently contacted to upper layer with reduction zone such as Fig. 2, raising H2Utilization
Rate or catalytic reforming coating and reduction zone are sufficiently mixed such as Fig. 3, make the H generated2Overflow is easy to react to also in situ with NOx
Generate NH3。
About LNT catalyst preparation method provided by the invention, there can be following preference:
Preferably, the first soluble metal salt solution described in preparation method, the second soluble metal salt solution can be
Identical soluble metal salt solution is also possible to different metal salt solutions.
Further, in step 1,
Preferably, first soluble metallic salt is barium acetate, barium nitrate, potassium nitrate, strontium nitrate or other alkalinity gold
Belong to one or more of salt.
Further, the first metal oxide described in preparation method, the second metal oxide, third metal oxide can be with
It is identical metal oxide, is also possible to different metal oxides.
Further, first metal oxide be aluminium oxide, cerium zirconium compound oxide, in magnesium aluminate spinel, cerium oxide
One or more.
Preferably, the first soluble metal salt solution is with equi-volume impregnating or excessive impregnation to metal oxide
On.
Further, second soluble metallic salt is one of nickel nitrate, manganese nitrate or other soluble-salts or several
Kind.
Further, second metal oxide is one of cerium zirconium compound oxide, aluminium oxide, cerium zirconium aluminum oxide
Or it is several.
Preferably, the second soluble metal salt solution equi-volume impregnating or excessive impregnation are aoxidized to the second metal
In object.
Further, noble metal precursor body is containing soluble metallic salt one or more of in platinum, palladium, rhodium.Before noble metal
Driving body includes the first noble metal precursor body, the second noble metal precursor body.The first noble metal precursor body, the second noble metal precursor
Body may be the same or different.
Preferably, noble metal precursor body is selected from platinum nitrate, chloroplatinic acid, palladium chloride, palladium nitrate, nitric acid tetramine platinum, nitric acid four
One or more of amine palladium, rhodium nitrate.
Further, the first noble metal precursor liquid solution is loaded into WN.
Further, the second noble metal precursor liquid solution is loaded into W0.
Further, third noble metal precursor liquid solution is loaded into third metal oxide.
Preferably, the first noble metal precursor liquid solution is with equi-volume impregnating or excessive impregnation into WN.It is preferred that
Ground, the first noble metal precursor liquid solution are the noble metal precursor liquid solutions containing Pt.
Preferably, the second noble metal precursor liquid solution is with equi-volume impregnating or excessive impregnation into W0.It is preferred that
Ground, the second noble metal precursor liquid solution are the noble metal precursor liquid solutions containing at least one of Pt, Pd.
Preferably, third noble metal precursor liquid solution is with equi-volume impregnating or excessive impregnation to third metal oxygen
In compound.Preferably, the third noble metal precursor liquid solution is the noble metal precursor liquid solution containing Rh.
Preferably, the third metal oxide is one of cerium zirconium compound oxide, aluminium oxide, cerium zirconium aluminum oxide
Or it is several.
Preferably, noble metal precursor liquid solution is also added with auxiliary agent, can not also add auxiliary agent.
Noble metal and noble metal precursor liquid solution can be single noble metal precursor liquid solution, be also possible to your a variety of gold
Belong to the mixing of precursor solution or the mixing of precursor solution and auxiliary agent salting liquid.Preferably, the metallic salt is preferably
Nitrate, acetate or other solubility salts.
Further, step 2, W1 precious metals pt: Pd: Rh ratio is preferably 2: 1: 0~1: 0: 0, W2 precious metals pt: Pd: Rh
Ratio is preferably 1: 1: 0~1: 0: 0, W3 precious metals pt: Pd: Rh ratio is preferably 1: 1: 1~0: 0: 1.
Noble metal is based on Pt in W1, and Pd is as auxiliary.It is distributed in the oxide with the noble metal of the low Pd of high Pt, it can be significantly
The HC for improving catalyst is reformed and water gas reaction, improves H2Yield to promoting NH3Generation.
Further, step 2, cerium zirconium compound oxide in the W1, aluminium oxide, cerium zirconium aluminum oxide, in cerium oxide, Ce is accounted for
Than being preferably 0~30%, Zr accounting 0~95%, cerium content is no more than 30% in oxide.
Further, step 2, Mg content accounting 2~50% in magnesium aluminate spinel in the W2.The alkali metal elements such as cerium, barium
With incipient impregnation point in magnesium aluminate spinel, cerium oxide, alkali metal accounting 0-20% in the oxide.
Further, step 2, magnesium aluminate spinel in the W1, in cerium oxide, in terms of metal oxide, NiO2Content accounting 2
~5%, MnO2Content 0-20%.Nickel manganese element is impregnated in cerium zirconium compound oxide, aluminium oxide, cerium zirconium aluminium with equi-volume impregnating
In oxide, cerium oxide.
Further, in step 3, the first bonding agents are including but not limited to one of Aluminum sol, silica solution, zirconium colloidal sol
Or it is several.
Further, in step 4, the second bonding agents are including but not limited to one of Aluminum sol, silica solution, zirconium colloidal sol
Or it is several.
Preparation method of the present invention is application and expansion based on orthodox car tail-gas catalyst preparation method, it is preferable that is urged
The carrier of agent is including but not limited to cordierite, the pass-through type of metal material or wall-flow type carrier.This method simple process, operation
Simplicity, it is at low cost.
Ba has highest storage capacity to NOx when surface is distributed, and the storage and reduction of the NOx of Ba base LNT is by aging
Influence, under Ce-Zr existence condition, LNT ageing-resistant ability is stronger.
Alkali metal and/or alkaline-earth metal have influence to NOx storage in LNT.
LNT component property influences and working mechanism, specific works mechanism are as follows:
Lean state:
Oxidation:
NO+O2→NO2
Trapping:
4NO2+2MCO3+O2→2M(NO)3+2CO2
Rich state:
Release:
M(NO3)2+2CO→MCO3+NO2+NO+CO2
Reduction:
NO2+CO→NO+CO2
2NO+2CO→N2+CO2
2NO+H2→N2+H2O
2NO+5H2→2NH3+H2O
For the work in every for meeting LNT, the composition of LNT catalyst cannot lack NO oxidative function, NOx trap function, NOx
Release function, NOx restoring function.And it is N that selective reduction is needed in NOx reduction2And NH3.According to the above mechanism, H2It is NH3
The reactant of generation, if NH need to be improved3Yield, then need to just improve reactant H2Amount.Although containing in diesel engine vent gas
Some H2, but measure lower.If NH need to be improved deliberately3Production quantity, then needing LNT to be also equipped with catalysis generates H2Ability.
Below with reference to test example and specific embodiment, the present invention is described in further detail.But this should not be understood
It is all that this is belonged to based on the technology that the content of present invention is realized for the scope of the above subject matter of the present invention is limited to the following embodiments
The range of invention.
<example 1>
Nickel nitrate and manganese nitrate solution are mixed, cerium zirconium aluminum composite oxides (specific surface is loaded to equi-volume impregnating
Product BET=120m2/ g, CeO2: 10%, ZrO2: 10%) in, 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2%Ni-5%Mn/
CZA is denoted as WN-1.
Platinum nitrate precious metal solution is loaded in WN-1 with equi-volume impregnating, 60 DEG C of dry 12h, 400 DEG C of roasting 2h,
1.7%Pt/CZA is obtained, W1-1 is denoted as.
Cerous nitrate and barium nitrate solution are loaded into magnesium aluminate spinel (BET=150m with equi-volume impregnating2/ g,
MgO:10% in), 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2.0%Ce-10%Ba/MAO, are denoted as W0-1.
Platinum nitrate precious metal solution is loaded in W0-1 with equi-volume impregnating, 60 DEG C of dry 12h, 400 DEG C of roasting 2h,
1.7%Pt/MAO-Ce-Mg is obtained, W2-1 is denoted as.
Rhodium nitrate solution is loaded into aluminium oxide (BET=170m with equi-volume impregnating2/ g) in, 60 DEG C of dry 12h,
400 DEG C of roasting 2h, obtain 2.25%Rh/Al2O3, it is denoted as W3-1.
W1-1, W2-1, W3-1 are mixed with bonding agent Aluminum sol, W1-1 accounting 40%, W2-1 accounting 40%, W3-1 accounting
15%, bonding agent accounting 5%, ball milling 10min obtains solid content 40%, D50=5 μm of slurry N1-1.
N1-1 is coated to cordierite carrier, cordierite carrier specification Φ 143.2*76.2/400cpsi-4mil.Through 60
Again through 550 DEG C of roasting 2h after DEG C dry 6h, catalyst C1, butt coated weight 250g/L, bullion content 120g/ft are obtained3, expensive
Pt metal: Pd: Rh ratio 4: 0: 1.
<example 2>
Nickel nitrate and manganese nitrate solution are mixed, cerium zirconium aluminum composite oxides (BET=is loaded to equi-volume impregnating
120m2/ g, CeO2: 10%, ZrO2: 10%) in, 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2%Ni-5%Mn/CZA, note
For WN-2.
The mixed noble metal solution of platinum nitrate, palladium nitrate is loaded in WN-2 with equi-volume impregnating, 60 DEG C of dryings
12h, 400 DEG C of roasting 2h, obtains 1.7%Pt1Pd1/ CZA, is denoted as W1-2.
Cerous nitrate and barium nitrate solution are loaded into magnesium aluminate spinel (BET=150m with equi-volume impregnating2/ g,
MgO:10% in), 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2.0%Ce-10%Ba/MAO, are denoted as W0-2.
The mixed noble metal solution of platinum nitrate, palladium nitrate is loaded in W0-2 with equi-volume impregnating, 60 DEG C of dryings
12h, 400 DEG C of roasting 2h, obtains 1.7%Pt1Pd1/ MAO-Ce-Mg (Pt: Pd=1: 1), is denoted as W2-2.
Rhodium nitrate solution is loaded into aluminium oxide (BET=170m with equi-volume impregnating2/ g) in, 60 DEG C of dry 12h,
400 DEG C of roasting 2h, obtain 2.25%Rh/Al2O3, it is denoted as W3-2.
W1-2, W2-2, W3-2 are mixed with bonding agent Aluminum sol, W1-2 accounting 40%, W2-2 accounting 40%, W3-2 accounting
15%, bonding agent accounting 5%, ball milling 10min obtains solid content 40%, D50=5 μm of slurry N1-2.
N1-2 is coated to cordierite carrier, cordierite carrier specification is the same as example 1.Again through 550 after 60 DEG C of dry 6h
DEG C roasting 2h, obtain catalyst C2, butt coated weight 250g/L, bullion content 120g/ft3, precious metals pt: Pd: Rh ratio 2
∶2∶1。
<example 3>
The mixed noble metal solution of platinum nitrate, palladium nitrate is loaded into cerium zirconium aluminum composite oxides with equi-volume impregnating
(BET=120m2/ g, CeO2: 10%, ZrO2: 10%) in, 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 1.7%Pt1Pd1/
CZA is denoted as W1-3.
Cerous nitrate and barium nitrate solution are loaded into magnesium aluminate spinel (BET=150m with equi-volume impregnating2/ g,
MgO:10% in), 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2.0%Ce-10%Ba/MAO, are denoted as W0-3.
The mixed noble metal solution of platinum nitrate, palladium nitrate is loaded in W0-3 with equi-volume impregnating, 60 DEG C of dryings
12h, 400 DEG C of roasting 2h, obtains 1.7%Pt1Pd1/ MAO-Ce-Mg, is denoted as W2-3.
Rhodium nitrate solution is loaded into aluminium oxide (BET=170m with equi-volume impregnating2/ g) in, 60 DEG C of dry 12h,
400 DEG C of roasting 2h, obtain 2.25%Rh/Al2O3, it is denoted as W3-3.
W1-3, W2-3, W3-3 are mixed with bonding agent Aluminum sol, W1-3 accounting 40%, W2-3 accounting 40%, W3-3 accounting
15%, bonding agent accounting 5%, ball milling 10min obtains solid content 40%, D50=5 μm of slurry N1-3.
N1-3 is coated to cordierite carrier, cordierite carrier specification is the same as example 1.Again through 550 after 60 DEG C of dry 6h
DEG C roasting 2h, obtain catalyst C3, butt coated weight 250g/L, bullion content 120g/ft3, precious metals pt: Pd: Rh ratio 2
∶2∶1。
<example 4>
Nickel nitrate and manganese nitrate solution are mixed, cerium zirconium aluminum composite oxides (BET=is loaded to equi-volume impregnating
120m2/ g, CeO2: 10%, ZrO2: 10%) in, 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2%Ni-5%Mn/CZA, note
For WN-4.
Platinum nitrate precious metal solution is loaded in WN-4 with equi-volume impregnating, 60 DEG C of dry 12h, 400 DEG C of roasting 2h,
1.82%Pt/CZA is obtained, W1-4 is denoted as.
Cerous nitrate and barium nitrate solution are loaded into magnesium aluminate spinel (BET=150m with equi-volume impregnating2/ g,
MgO:10% in), 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2.0%Ce-10%Ba/MAO, are denoted as W0-4.
Platinum nitrate precious metal solution is loaded in W0-4 with equi-volume impregnating, 60 DEG C of dry 12h, 400 DEG C of roasting 2h,
1.82%Pt/MAO-Ce-Mg is obtained, W2-4 is denoted as.
Rhodium nitrate solution is loaded into aluminium oxide (BET=170m with equi-volume impregnating2/ g) in, 60 DEG C of dry 12h,
400 DEG C of roasting 2h, obtain 1.62%Rh/Al2O3, it is denoted as W3-4.
W1-4, W2-4 are mixed with bonding agent Aluminum sol, W1-4 accounting 47.5%, W2-4 accounting 47.5%, bonding agent accounts for
Than 5%, ball milling 10min obtains solid content 40%, D50=5 μm of slurry N1-4.
W3-4 is mixed with bonding agent Aluminum sol, W3-4 accounting 95%, bonding agent accounting 5%, ball milling 10min, consolidate
Content 40%, D50=5 μm of slurry N2-4.
Slurry N1-4 is coated to cordierite carrier, cordierite carrier specification is the same as example 1.It is passed through again after 60 DEG C of dry 6h
550 DEG C of roasting 2h, obtain catalyst C4-0, butt coated weight 195g/L.
Slurry N2-4 is coated to C4-0, obtains catalyst C4 through 550 DEG C of roasting 2h again after 60 DEG C of dry 6h, is done
Base coated weight 250g/L, bullion content 120g/ft3, precious metals pt: Pd: Rh ratio 4: 0: 1.
<example 5>
Nickel nitrate and manganese nitrate solution are mixed, cerium zirconium aluminum composite oxides (BET=is loaded to equi-volume impregnating
120m2/ g, CeO2: 10%, ZrO2: 10%) in, 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2%Ni-5%Mn/CZA, note
For WN-5.
The mixed noble metal solution of platinum nitrate, palladium nitrate is loaded in WN-5 with equi-volume impregnating, 60 DEG C of dryings
12h, 400 DEG C of roasting 2h, obtains 1.82%Pt1Pd1/ CZA, is denoted as W1-5.
Cerous nitrate and barium nitrate solution are loaded into magnesium aluminate spinel (BET=150m with equi-volume impregnating2/ g,
MgO:10% in), 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2.0%Ce-10%Ba/MAO, are denoted as W0-5.
The mixed noble metal solution of platinum nitrate, palladium nitrate is loaded in W0-5 with equi-volume impregnating, 60 DEG C of dryings
12h, 400 DEG C of roasting 2h, obtains 1.82%Pt1Pd1/ MAO-Ce-Mg, is denoted as W2-5.
Rhodium nitrate solution is loaded into aluminium oxide (BET=170m with equi-volume impregnating2/ g) in, 60 DEG C of dry 12h,
400 DEG C of roasting 2h, obtain 1.62%Rh/Al2O3, it is denoted as W3-5.
W1-5, W2-5 are mixed with bonding agent Aluminum sol, W1-5 accounting 47.5%, W2-5 accounting 47.5%, bonding agent accounts for
Than 5%, ball milling 10min obtains solid content 40%, D50=5 μm of slurry N1-5.
W3-5 is mixed with bonding agent Aluminum sol, W3-5 accounting 95%, bonding agent accounting 5%, ball milling 10min, consolidate
Content 40%, D50=5 μm of slurry N2-5.
Slurry N1-5 is coated to cordierite carrier, cordierite carrier specification is the same as example 1.It is passed through again after 60 DEG C of dry 6h
550 DEG C of roasting 2h, obtain catalyst C5-0, butt coated weight 195g/L.
Slurry N2-5 is coated to C5-0, obtains catalyst C5 through 550 DEG C of roasting 2h again after 60 DEG C of dry 6h, is done
Base coated weight 250g/L, bullion content 120g/ft3, precious metals pt: Pd: Rh ratio 2: 2: 1.
<example 6>
Platinum nitrate is expensive, palladium nitrate mixed metal solution loads to cerium zirconium aluminum composite oxides with equi-volume impregnating
(BET=120m2/ g, CeO2: 10%, ZrO2: 10%) in, 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 1.82%Pt1Pd1/
CZ is denoted as W1-6.
Cerous nitrate and barium nitrate solution are loaded into magnesium aluminate spinel (BET=150m with equi-volume impregnating2/ g,
MgO:50% in), 60 DEG C of dry 12h, 400 DEG C of roasting 2h obtain 2.0%Ce-10%Ba/MAO, are denoted as W0-6.
The mixed noble metal solution of platinum nitrate, palladium nitrate is loaded in W0-6 with equi-volume impregnating, 60 DEG C of dryings
12h, 400 DEG C of roasting 2h, obtains 1.82%Pt1Pd1/ MAO-Ce-Mg, is denoted as W2-6.
Rhodium nitrate solution is loaded into aluminium oxide (BET=170m with equi-volume impregnating2/ g) in, 60 DEG C of dry 12h,
400 DEG C of roasting 2h, obtain 1.62%Rh/Al2O3, it is denoted as W3-6.
W1-6, W2-6 are mixed with bonding agent Aluminum sol, W1-6 accounting 47.5%, W2-6 accounting 47.5%, bonding agent accounts for
Than 5%, ball milling 10min obtains solid content 40%, D50=5 μm of slurry N1-6.
W3-6 is mixed with bonding agent Aluminum sol, W3-6 accounting 95%, bonding agent accounting 5%, ball milling 10min, consolidate
Content 40%, D50=5 μm of slurry N2-6.
Slurry N1-6 is coated to cordierite carrier, cordierite carrier specification is the same as example 1.It is passed through again after 60 DEG C of dry 6h
550 DEG C of roasting 2h, obtain catalyst C6-0, butt coated weight 195g/L.
Slurry N2-6 is coated to C6-0, obtains catalyst C6 through 550 DEG C of roasting 2h again after 60 DEG C of dry 6h, is done
Base coated weight 250g/L, bullion content 120g/ft3, precious metals pt: Pd: Rh ratio 2: 2: 1.
<example 7>
Catalyst prod prepared by above-mentioned example is subjected to reactor test respectively, in the condition of simulation exhaust gas from diesel vehicle
Under, different catalyst prods is measured for the catalytic conversion efficiency of the NOx compound in tail gas.In test process, used
Simulation exhaust gas from diesel vehicle gas mixing ingredient and proportionate relationship it is as follows:
1 measurement atmosphere of table
| Gas | NO | C3H6(C1) | H2 | CO | O2 | H2O | CO2 | N2 |
| Lean | 200ppm | 100ppm | 0 | 0.1% | 10% | 5% | 5% | Balance |
| Rich | 200ppm | 5000ppm | 0.4% | 1% | 1% | 5% | 5% | Balance |
Sample preparation: sample is taken from full-page proof, is sampled at 1/2 radius, is denoted as C1~C6 respectively and indicates into outgassing direction, obtain
Φ 25.4*76.2/400cpsi sample.
Pretreatment: 550 DEG C of Lean atmosphere purge 1h.
Test: 10 Lean/Rich are recycled at 500/450/400/350/300/250/200/150 DEG C of steady state test of cooling
Circulation records NOx, HC, CO, NH3、H2O and CO2Concentration, calculate 10 circulation in NOx average conversion, NH3It is average to generate
Rate.C1-C6 catalyst NOx conversion rate compares as shown in figure 4, C1-C6 catalyst n H3Conversion ratio comparison is as shown in Figure 5.
Claims (10)
- Match the LNT catalyst used with SCR 1. a kind of, the LNT catalyst include in noble metal Rh and Pt, Pd at least It is a kind of；The LNT catalyst has layered structure, and surface layer Rh concentration is greater than the Rh concentration of internal layer.
- 2. LNT catalyst as described in claim 1, which is characterized in that the noble metal includes Pt；The surface layer the LNT Pt concentration Less than internal layer Pt concentration.
- 3. LNT catalyst as described in claim 1, which is characterized in that the noble metal catalyst further includes metal oxide, expensive Metal, alkalinous metal, Ni, Mn element.
- 4. LNT catalyst as claimed in claim 3, which is characterized in that the alkalinous metal refers to alkali metal and/or alkaline earth gold One or more of category, and/or rare earth alkaline element.
- 5. LNT catalyst as claimed in claim 3, which is characterized in that the metal oxide is including but not limited to aluminium oxide, cerium In the metal oxides such as zirconium mixed oxide, cerium zirconium aluminum composite oxides, sial composite oxides, magnesium aluminate spinel, cerium oxide One or more.
- 6. a kind of above-mentioned method for preparing catalyst, comprising the following steps:(1) the first soluble metal salt solution is impregnated on the first metal oxide, in terms of metal oxide, accounting 0- 20%, then 60-120 DEG C of dry 2-12h roasts 2-8h in air atmosphere, obtains basic matterial at a temperature of 350-650 DEG C W0；Second soluble metal salt solution is impregnated into the second metal oxide, in terms of metal oxide, accounting 0-20%, Then 60-120 DEG C of dry 2-12h roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains basic matterial WN；(2) the first noble metal precursor liquid solution is impregnated into WN, in terms of precious metal simple substance, accounting 0.1-5%, then 60- 120 DEG C of dry 2-12h roast 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtain noble metal catalyst W1；Second noble metal precursor liquid solution is impregnated into W0, in terms of precious metal simple substance, accounting 0.1-5%, then 60-120 DEG C Dry 2-12h, roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains noble metal catalyst W2；Third noble metal precursor liquid solution is impregnated into third metal oxide, then 60-120 DEG C of dry 2-12h, in 350- 2-8h is roasted in air atmosphere at a temperature of 650 DEG C, obtains noble metal catalyst W3；(3) W1, W2, W3 and first bonding agents are mixed, ball milling slurrying, W1 accounting 5 ~ 50%, W2 accounting 5 ~ 50%, W3 accounting 0 ~ 30%, first bonding agents accounting 1-10%, slurry solid content are controlled in 25-50%, slurry granularity D50Control is obtained at 2 μm -10 μm Precious Metal N1；(4) W2, W3 and second bonding agents are mixed, ball milling slurrying, W2 accounting 0 ~ 50%, W3 accounting 40-99%, second bonding agents account for Than 1-10%, slurry solid content is controlled in 25-50%, slurry granularity D50Control obtains Precious Metal N2 at 2 μm -10 μm；(5) slurry N1 is coated on carrier bottom, carrying capacity 100-300g/L, bullion content 5-120g/ft on coating3, in 60- Dry 2-12h, then roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains catalyst C0 at a temperature of 120 DEG C；(6) slurry N2 is coated on 0 upper layer of support C, carrying capacity 0-300g/L, bullion content 5-120g/ft3, in 60- on coating Dry 2-12h, then roasts 2-8h in air atmosphere at a temperature of 350-650 DEG C, obtains catalyst C at a temperature of 120 DEG C.
- 7. preparation method as claimed in claim 6, which is characterized in that in step 1,First soluble metallic salt is barium acetate, barium nitrate, potassium nitrate, one of strontium nitrate or other alkaline metal salts Or it is several；Or preferably, first metal oxide be aluminium oxide, cerium zirconium compound oxide, magnesium aluminate spinel, in cerium oxide One or more；Or preferably, the first soluble metal salt solution is with equi-volume impregnating or excessive impregnation to metal oxide On；Or preferably, second soluble metallic salt is one of nickel nitrate, manganese nitrate or other soluble-salts or several Kind；Or preferably, second metal oxide is cerium zirconium compound oxide, aluminium oxide, cerium zirconium aluminum oxide, cerium oxide One or more of；Or preferably, the second soluble metal salt solution equi-volume impregnating or excessive impregnation are aoxidized to the second metal In object.
- 8. preparation method as claimed in claim 6, which is characterized in that in step 2,Noble metal precursor body is containing soluble metallic salt one or more of in platinum, palladium, rhodium.
- 9. preparation method as claimed in claim 8, which is characterized in that noble metal precursor body is selected from platinum nitrate, palladium nitrate, nitric acid four One or more of amine platinum, tetraamine palladium nitrate, rhodium nitrate.
- 10. preparation method as claimed in claim 6, which is characterized in that the first noble metal precursor liquid solution is containing Pt Noble metal precursor liquid solution；The second noble metal precursor liquid solution is the noble metal precursor liquid solution containing at least one of Pt, Pd；The third noble metal precursor liquid solution is the noble metal precursor liquid solution containing Rh.
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| CN101282783A (en) * | 2005-10-05 | 2008-10-08 | 株式会社卡特勒 | Exhaust gas purification catalyst |
| CN101528348A (en) * | 2006-10-31 | 2009-09-09 | 株式会社科特拉 | Exhaust gas purifying catalyst |
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| CN104039426A (en) * | 2011-12-28 | 2014-09-10 | 丰田自动车株式会社 | Exhaust gas purification catalyst |
| CN106457215A (en) * | 2014-03-21 | 2017-02-22 | 巴斯夫公司 | Integrated LNT-TWC catalyst |
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| JPH06226053A (en) * | 1993-01-29 | 1994-08-16 | Mitsubishi Heavy Ind Ltd | Treatment of waste gas |
| CN101282783A (en) * | 2005-10-05 | 2008-10-08 | 株式会社卡特勒 | Exhaust gas purification catalyst |
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