CN114700085B - High-stability three-way catalyst and preparation method thereof - Google Patents
High-stability three-way catalyst and preparation method thereof Download PDFInfo
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- CN114700085B CN114700085B CN202210493392.4A CN202210493392A CN114700085B CN 114700085 B CN114700085 B CN 114700085B CN 202210493392 A CN202210493392 A CN 202210493392A CN 114700085 B CN114700085 B CN 114700085B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 134
- 238000002360 preparation method Methods 0.000 title claims abstract description 36
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 137
- 239000000463 material Substances 0.000 claims abstract description 91
- 230000003197 catalytic effect Effects 0.000 claims abstract description 79
- 238000000034 method Methods 0.000 claims abstract description 25
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 22
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052777 Praseodymium Inorganic materials 0.000 claims abstract description 14
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 claims abstract description 14
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000002245 particle Substances 0.000 claims abstract description 12
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 12
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 11
- 150000003624 transition metals Chemical class 0.000 claims abstract description 11
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 6
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims abstract description 6
- 230000008569 process Effects 0.000 claims abstract description 5
- 229910052779 Neodymium Inorganic materials 0.000 claims abstract description 4
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 4
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims abstract description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 410
- 229910052697 platinum Inorganic materials 0.000 claims description 194
- 239000010410 layer Substances 0.000 claims description 186
- 238000000576 coating method Methods 0.000 claims description 95
- 239000011248 coating agent Substances 0.000 claims description 85
- 239000000843 powder Substances 0.000 claims description 56
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- RCFVMJKOEJFGTM-UHFFFAOYSA-N cerium zirconium Chemical compound [Zr].[Ce] RCFVMJKOEJFGTM-UHFFFAOYSA-N 0.000 claims description 28
- 239000002002 slurry Substances 0.000 claims description 27
- 229910052751 metal Inorganic materials 0.000 claims description 25
- 239000002184 metal Substances 0.000 claims description 25
- -1 cerium zirconium aluminum Chemical compound 0.000 claims description 24
- 238000001035 drying Methods 0.000 claims description 24
- 238000002156 mixing Methods 0.000 claims description 24
- 239000008367 deionised water Substances 0.000 claims description 23
- 229910021641 deionized water Inorganic materials 0.000 claims description 23
- 239000010948 rhodium Substances 0.000 claims description 22
- 229910052703 rhodium Inorganic materials 0.000 claims description 20
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 19
- 239000011247 coating layer Substances 0.000 claims description 17
- 239000002243 precursor Substances 0.000 claims description 16
- 238000000498 ball milling Methods 0.000 claims description 14
- 238000010008 shearing Methods 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 13
- 239000011159 matrix material Substances 0.000 claims description 11
- 239000004480 active ingredient Substances 0.000 claims description 6
- 229910021193 La 2 O 3 Inorganic materials 0.000 claims description 4
- 239000011230 binding agent Substances 0.000 claims description 4
- 230000007704 transition Effects 0.000 claims description 4
- 239000011812 mixed powder Substances 0.000 claims description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 2
- 238000007581 slurry coating method Methods 0.000 claims 1
- 238000009826 distribution Methods 0.000 abstract description 3
- 238000011068 loading method Methods 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 3
- 238000005457 optimization Methods 0.000 abstract 1
- PXXKQOPKNFECSZ-UHFFFAOYSA-N platinum rhodium Chemical compound [Rh].[Pt] PXXKQOPKNFECSZ-UHFFFAOYSA-N 0.000 description 34
- 239000010970 precious metal Substances 0.000 description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 20
- 239000000243 solution Substances 0.000 description 14
- 239000000203 mixture Substances 0.000 description 12
- 239000011164 primary particle Substances 0.000 description 11
- 229910052742 iron Inorganic materials 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
- 238000000746 purification Methods 0.000 description 5
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 4
- NWAHZABTSDUXMJ-UHFFFAOYSA-N platinum(2+);dinitrate Chemical compound [Pt+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O NWAHZABTSDUXMJ-UHFFFAOYSA-N 0.000 description 4
- 239000000853 adhesive Substances 0.000 description 3
- 230000001070 adhesive effect Effects 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 229910052763 palladium Inorganic materials 0.000 description 3
- 238000004220 aggregation Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 239000012050 conventional carrier Substances 0.000 description 2
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 description 1
- 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
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- PDBFXISAEVVUEJ-UHFFFAOYSA-H O[Pt](O)(O)(O)(O)O Chemical compound O[Pt](O)(O)(O)(O)O PDBFXISAEVVUEJ-UHFFFAOYSA-H 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- NOWPEMKUZKNSGG-UHFFFAOYSA-N azane;platinum(2+) Chemical compound N.N.N.N.[Pt+2] NOWPEMKUZKNSGG-UHFFFAOYSA-N 0.000 description 1
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- 150000004985 diamines Chemical class 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000002987 primer (paints) Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 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 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000002344 surface layer Substances 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
- B01J23/70—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
- B01J23/894—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 rare earths or actinides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8628—Processes characterised by a specific catalyst
-
- B01J35/56—
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Environmental & Geological Engineering (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Catalysts (AREA)
Abstract
The invention belongs to the technical field of three-way catalysts and preparation, and particularly relates to a high-stability three-way catalyst and a preparation method thereof. According to the distribution of transition metal or noble metal in different catalyst layers, the optimization selection of sol A and sol B is carried out, wherein sol A is mainly matched with noble metal Pt; the B sol is mainly matched with noble metal Rh. Sol A is mainly cerium sol or praseodymium sol and other sol capable of providing variable valence, and sol B is mainly zirconium sol, neodymium sol, lanthanum sol, yttrium sol and other sol materials capable of giving electrons; meanwhile, controlling the particle size of the sol A and the sol B to be not more than 25nm; the three-way catalyst can better load sol in micropores of the catalytic material in the preparation process, and the three catalytic materials, the sol and the noble metal can form stable chemical bonds in the final three-way catalyst product by combining the processes of loading, roasting and the like of the subsequent noble metal, so that the stability of the catalyst is greatly improved.
Description
Technical Field
The invention belongs to the technical field of three-way catalysts and preparation, and particularly relates to a high-stability three-way catalyst and a preparation method thereof.
Background
The current stage of domestic motorcycle emission standard implementation stage 4, each pollutant limit value is CO=1140 mg/km, THC=380 or 170mg/km (related to motorcycle emission), NOx=70 or 90 mg/km (related to motorcycle emission), and European beginning implementation stage 5 emission standard of 1 month and 1 day in 2020, relative to the stage 4 emission standard, the emission limit values of three pollutants in the stage 5 emission regulation are 87.7%, 26.3% and 85.7% of the stage 4 emission limit value respectively, wherein the descending amplitude of THC is the largest, and the early test research finds that the stage 4 catalyst can not directly meet the requirement of the stage 5 emission regulation, the catalyst technology needs to be upgraded urgently, and the catalyst has high HC purification performance and quick ignition and good durability. The catalyst for gasoline car usually adopts palladium noble metal to load on alumina material to solve HC purification problem, and the selling price of the hot-sold motorcycle is generally below 0.8 ten thousand yuan, and the catalyst containing palladium is used to purify HC, so that the cost pressure of the main engine factory is higher. At present, the noble metal of platinum is the cheapest of three common noble metals of platinum, palladium and rhodium, the noble metal of rhodium is the cheapest of three noble metals, and in order to improve the cost performance of the motorcycle Europe five catalyst, a high-proportion platinum catalyst and a low-proportion rhodium catalyst are ideal choices, but the high-proportion platinum catalyst has the problems of high temperature volatilization, high temperature aggregation and the like, and the high-proportion platinum catalyst has poor thermal stability.
In order to overcome the technical problems of the catalyst, the patent with the application number of 202110499957.5 discloses a Pt-containing gasoline car three-way catalyst and a preparation method thereof. By Al (NO) 3 ) 3 ·9H 2 O wrapping process using Al (NO 3 ) 3 ·9H 2 O wraps Pt in alumina with large specific surface area, so that migration and diffusion of Pt are inhibited, and thermal stability of Pt is improved; platinum migration is inhibited by alumina having a large specific surface area, but the catalytic activity of platinum is also inhibited.
Disclosure of Invention
The invention aims at: aiming at the technical problem of poor stability of noble metal platinum in the prior art, the high-stability three-way catalyst and the preparation method thereof are provided.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a three-way catalyst, which is a catalyst,
the coating comprises a metal matrix and at least two layers of coatings coated on the metal matrix, wherein the coatings comprise a bottom layer coating and a top layer coating which are sequentially coated on the metal matrix;
the bottom coating takes transition metal and/or noble metal platinum as an active ingredient, and is prepared by firstly mixing sol A with a first catalytic material, drying, mixing with a precursor solution containing the active ingredient to prepare bottom slurry, and coating, drying and roasting;
the top layer coating takes metal platinum and metal rhodium as active components, and is prepared by mixing and drying a second catalytic material with sol A or sol B respectively, mixing with precursor solution containing corresponding active components to prepare top layer slurry, and coating, drying and roasting;
the particle size range of the sol A and the sol B is not more than 25nm;
the sol A comprises any one or a combination of a plurality of cerium sol and praseodymium sol;
the sol B comprises any one or a combination of a plurality of zirconium sol, neodymium sol, lanthanum sol and yttrium sol.
The sol A or the sol B is a nano ion aqueous solution corresponding to rare earth elements.
In the three-way catalyst, sol A and sol B are selected according to different catalyst layers, wherein the sol A is mainly matched with noble metal Pt; the B sol is mainly matched with noble metal Rh. Sol A is mainly cerium sol or praseodymium sol and other sol capable of providing variable valence, and sol B is mainly zirconium sol, neodymium sol, lanthanum sol, yttrium sol and other sol materials capable of giving electrons; meanwhile, controlling the particle size of the sol A and the sol B to be not more than 25nm; the three-way catalyst can better load sol in micropores of the catalytic material in the preparation process, and the three catalytic materials, the sol and the noble metal can form stable chemical bonds in the final three-way catalyst product by combining the processes of loading, roasting and the like of the subsequent noble metal, so that the stability of the catalyst is greatly improved.
As a preferred technical scheme of the invention, the first catalytic material comprises a cerium-zirconium material A and a cerium-zirconium-aluminum material; the cerium-zirconium material A comprises CeO with the Ce content not less than 40wt% 2 ；
The second catalytic material comprises a cerium-zirconium material A, a cerium-zirconium material B and a cerium-zirconium-aluminum material; the cerium-zirconium material B comprises CeO with the Ce content not exceeding 40 percent 2 。
The inventors found in the research and development process that CeO in the cerium-zirconium material in different coatings 2 The difference of the content has a great relation with the matching property of noble metals in each coating; noble metal Pt and cerium-zirconium material with Ce content higher than 40% are combinedThe use can improve the utilization rate of noble metal Pt and the oxidation performance and durability of the catalyst; also, the combination of Rh and Ce-Zr material with Ce content lower than 40% can raise the NOx reducing performance of the catalyst. Thus, cerium-zirconium material a is distributed in the primer coating and in the top coating, while cerium-zirconium material B is distributed only in the top coating.
As a preferred technical scheme of the present invention, in the cerium-zirconium material a: comprises CeO with 40-100% of Ce 2 The balance of ZrO 0-60 wt% 2 、La 2 O 3 、Y 2 O 3 One or more combinations of the above;
the cerium-zirconium material B comprises the following components: comprises CeO with Ce content of 5-40% 2 Zr content of 50-85% ZrO 2 The balance of 5 to 10 weight percent of La 2 O 3 、Y 2 O 3 、Pr 6 O 11 、Nd 2 O 3 One or more combinations of the above).
The three-way catalyst comprises the following components:
the total noble metal content is 10-50g/ft 3 Wherein, the content of the metal platinum accounts for 50-95% of the total noble metal content, and the balance is noble metal rhodium;
the content of the transition metal in the bottom coating is 0-100g/ft 3 ；
The content of platinum in the bottom layer coating is 0.1-10% of the total content of platinum, and the content of platinum in the top layer coating is 90-99.9% of the total content of platinum.
As a preferable technical scheme of the invention, the bottom coating comprises a first coating and a second coating from bottom to top, wherein the first coating is a transition metal-based catalytic layer, or a platinum-based catalytic layer, or a transition metal-platinum-based catalytic layer; the second coating is a platinum-based catalytic layer, or a transition metal-platinum-based catalytic layer.
In the three-way catalyst, under the condition that the total coating amount is determined, the coating layer has better coating effect in times compared with single coating effect, on one hand, the slurry is firmly adhered on the metal carrier and is not easy to fall off; on the other hand, the concentration gradient arrangement of noble metal can be realized through layering, the oxygen storage capacity of the coating can be improved by configuring fewer noble metals on the bottom layer, the three-effect window performance of the catalyst is further improved, and the high airspeed resistance of the catalyst is mainly improved by configuring more noble metals on the surface layer. The space distribution of noble metal in the catalyst is effectively optimized, and the utilization rate is improved.
As a preferable technical scheme of the invention, the cerium-zirconium-aluminum material comprises CeO with the Ce content of 5-20 percent 2 ZrO with Zr content of 5-10% 2 ，La 2 O 3 And Y 2 O 3 1-5% of mixed material and the balance of Al 2 O 3 。
As a preferable technical scheme of the invention, the granularity of the cerium-zirconium-aluminum material is 6-50 mu m.
As a preferable technical scheme of the invention, the coating amount of the first coating and the second coating is respectively 30-60g/L, and the coating amount of the third coating is 40-80 g/L.
In the bottom layer coating and the top layer coating, the difference of cerium, zirconium and aluminum materials is mainly from the whole consideration of the coating, and from the aspect of Ce content, the material with about 10 percent of Ce content of each layer accounts for about 60 percent, and the material with 60 percent of Ce content accounts for more than 30 percent; from the distribution, the oxygen storage amount of the coating is ensured to be enough, the catalytic performance under the condition of changing the air-fuel ratio can be solved, and the catalyst reaction window is improved.
As a preferable technical scheme of the invention:
the sol A accounts for 0.5% -5% of the weight of the first catalytic material or the second catalytic material;
the sol B accounts for 0.5-5% of the weight of the first catalytic material or the second catalytic material.
The preparation method of the three-way catalyst comprises the steps of respectively preparing slurry of each layer according to a coating structure of the three-way catalyst, then coating the slurry on a metal honeycomb carrier in a layered manner, coating each layer of slurry on the carrier, drying and roasting, and then coating the slurry of the next coating;
the slurry of the bottom coating is prepared in the following manner:
step 1.1: adding deionized water into the sol A, uniformly mixing with the cerium-zirconium material A and/or the cerium-zirconium-aluminum material after shearing, and drying at 80-150 ℃ for 1-2 hours; obtaining powder A; the particle size range of the sol A after shearing is not more than 25nm;
step 1.2: adding deionized water into precursor solution of noble metal and/or transition metal, stirring uniformly, mixing with powder A, stirring, and drying at 80-150 ℃ for 1-2 hours; roasting the dried mixed powder for 1-2 hours at 500-850 ℃ to obtain powder A containing active components;
step 1.3: adding a binder into the powder A containing the active components obtained in the step 1.2, ball milling, adding deionized water, and continuing ball milling to obtain a bottom layer slurry;
the slurry of the top coat is prepared as follows:
preparing powder B containing noble metal platinum and powder C containing noble metal rhodium respectively, uniformly mixing the powder B and the powder C, adding a binder, ball-milling, adding deionized water, and continuing ball-milling to obtain the top-layer slurry.
As a preferred embodiment of the present invention, the powder A containing the active ingredient comprises the following:
(1) powder of active component mixed with cerium-zirconium-aluminum material;
(2) powder of cerium-zirconium-aluminum material, mixture of cerium-zirconium material A and active component mixed proportionally;
(3) a mixture of an active component and a cerium-zirconium-aluminum material, a mixture of an active component and a cerium-zirconium material A, and a powder mixed by the two mixtures.
Wherein the active component is transition metal, noble metal platinum or a mixture of overplated metal and noble metal platinum.
As a preferred technical solution of the present invention,
powder C containing noble rhodium was prepared as follows:
step 2.1: adding deionized water into the sol B, wherein the water adding amount is equal to the water pore volume of the material multiplied by the weight of the material, shearing uniformly, mixing the sol B and the cerium-zirconium material B uniformly, and drying in an oven at 80-150 ℃ for 1-2 hours; obtaining powder C; the particle size range of the sol after shearing is not more than 25nm;
step 2.2: adding deionized water into precursor solution of noble metal rhodium, stirring uniformly, adding water with the volume equal to the water pore volume multiplied by 0.95 of the material multiplied by the weight of the material, mixing with powder C, drying in an oven at 80-150 ℃ for 1-2 hours after stirring uniformly, and roasting the dried powder in air at 500-850 ℃ for 1-2 hours to obtain powder C containing noble metal rhodium.
The preparation process of the powder B containing noble metal platinum is similar to that of the powder A containing noble metal platinum; the specific steps are as follows:
step 3.1: adding deionized water into the sol A, uniformly shearing, uniformly mixing with a cerium-zirconium-aluminum material and/or a cerium-zirconium material A, and drying at 80-150 ℃ for 1-2 hours; obtaining powder B; the particle size range of the sol after shearing is not more than 25nm;
step 3.2: adding deionized water into precursor solution of noble metal platinum, adding water amount equal to the water pore volume multiplied by 0.95 times the weight of the material, stirring uniformly, drying in an oven at 80-150 ℃ for 1-2 hours, and roasting the dried powder in air at 500-850 ℃ for 1-2 hours to obtain powder B containing active components.
Preferably, the powder B containing the noble metal platinum includes any one of the following cases:
(1) powder of noble metal platinum mixed with cerium-zirconium-aluminum material;
(2) powder of cerium-zirconium-aluminum material, mixture of cerium-zirconium material A and noble metal platinum mixed according to a certain proportion;
(3) a mixture 1 of noble metal platinum and cerium zirconium aluminum material, a mixture 2 of noble metal platinum and cerium zirconium material A,
the mixture 1 and the mixture 2 are mixed according to a certain proportion to obtain powder.
As a preferred technical scheme of the invention, the precursor solution of the transition metal is one or two of soluble ferric nitrate and cobalt nitrate;
as a preferable technical scheme of the invention, the cerium-zirconium-aluminum material accounts for 50-90% of the content of the bottom layer coating, and the cerium-zirconium-aluminum material accounts for 20-50% of the content of the top layer coating.
As a preferable technical scheme of the invention, precursor solutions of the noble metal platinum and the noble metal rhodium are respectively any one of soluble organic noble metal salt solution, nitrate and acetate;
preferably, the precursor solution of the noble metal platinum is: is hexahydroxy platinum acid diethanolamine, 2-hydroxy ethyl ammonia hexahydrogen platinum, diamine tetraamine platinum and dinitrodiammine platinum.
Preferably, the metal matrix is a metal honeycomb cylindrical structure and can be a common honeycomb carrier or a novel turbulence carrier (LS/BC) structural carrier.
In summary, due to the adoption of the technical scheme, the beneficial effects of the invention are as follows:
1. the high-stability three-way catalyst provided by the invention has the advantages of high noble metal utilization rate, inhibition of high-temperature self-aggregation of noble metal and good durability; even in the case where the noble metal content is low, good HC purifying catalytic activity is exhibited.
2. According to the high-stability three-way catalyst provided by the invention, three catalyst layers are designed, and according to the types of active ingredients in different catalyst coatings, the types of sol are optimized in a targeted manner, so that the variable-valence sol and platinum noble metal load are provided; the prepared three-way catalyst has better purification performance and better NOx purification capability for the sol and rhodium noble metal load which can provide electrons.
3. According to the high-stability three-way catalyst provided by the invention, the structure of the catalytic material is further optimized according to the types of active ingredients in different catalyst coatings, and the noble metal Pt and the cerium-zirconium material A with the Ce content higher than 40% are combined for use, so that the utilization rate of the noble metal Pt is improved, and the oxidation performance and the durability of the catalyst are improved; the noble metal Rh and the cerium-zirconium material B with the Ce content lower than 40% are combined for use, so that the reduction performance of the catalyst on NOx can be improved.
4. According to the preparation method of the high-stability three-way catalyst, in the preparation process of slurry with different coatings, the nano-size of the primary particle size of sol is controlled, the sol is loaded in micropores of a catalytic material, dried and then loaded with a noble metal precursor solution, finally the catalyst is roasted together, noble metal and the sol are roasted together, and the stable chemical bond can be formed by the material, the sol and the noble metal, so that the stability of the catalyst is improved.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The invention provides a high-stability three-way catalyst, which comprises a metal matrix and three coatings coated on the metal matrix, wherein the three coatings are coated on the metal matrix; a first coating, a second coating and a third coating respectively; wherein the total noble metal content in the three-way catalyst is 10-50g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the The particle size range of the sol is not more than 20nm; the vector is a (BC) vector/conventional vector.
The following gives a summary of the detailed technical points of the three-way catalyst according to the invention, based on the different coatings: specific parameter requirements are shown in table 1 below:
table 1 shows the parameter requirements for three coatings of the three-way catalyst
S represents a cerium zirconium aluminum material;
the parameter requirements for each coating summarized in table 1 above; the preparation of the following catalyst was carried out:
example 1
The present embodiment provides a three-way catalyst; the former stage adopts a cylindrical metal matrix with a conventional carrier diameter of 42mm, a height of 60mm and a pore size of 200cpsi, the latter stage adopts a novel turbulent flow (BC) carrier with a diameter of 53mm, a height of 100mm and a pore size of 300/600cpsi, and the volume of the carrier is 0.279L.
The coating structure is from down to up in turn: iron-based catalytic layer + platinum-rhodium-based catalytic layer;
the total amount of the iron-based catalytic layer is 10g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the The noble metal content of the platinum-rhodium base catalytic layer is 25g/ft 3 ；
Precious metal ratio (Pt: rh) =4:1;
the platinum noble metal accounts for 81.1 percent of the total noble metal, the second coating platinum accounts for 6.97 percent of the total platinum consumption, and the third coating platinum accounts for 93.03 percent of the total platinum consumption;
the first coating and the second coating adopt cerium sol, and cerium sol A accounts for 2.5 percent of the weight of the loaded sol material;
the third coating adopts cerium sol and zirconium sol, wherein cerium sol A accounts for 1.5% of the weight of the loaded sol material, and zirconium sol B accounts for 1.5% of the weight of the loaded sol material;
the weight of the cerium zirconium aluminum material of the first coating layer accounts for 57 percent of the weight of the coating layer, the cerium zirconium aluminum material of the second coating layer accounts for 57 percent of the coating layer, and the cerium zirconium aluminum material of the third coating layer accounts for 30 percent of the coating layer.
The primary particle diameter of the sol is controlled to be about 15 nm.
Table 2 is a comparative table of parameters for each coating of catalyst A-1
The specific preparation method of the three-way catalyst comprises the following steps:
(1) the preparation process of the first coating comprises the following steps:
76.5g of ionized water was added to 11.1g of cerium sol (sol content: 21%) and the cerium sol and 60g of Ce were sheared at high speed to a primary particle size of 10.5nm 10 Zr 10 Y 5 AL 75 (particle size of 15.4 μm) and33g Ce 60 Zr 30 Y 5 La 5 the materials are dried in a baking oven at 120 ℃ for 2 hours after being uniformly mixed;
adding 72.7g of deionized water into 4.44g of ferric nitrate, uniformly stirring, drying in a baking oven at 150 ℃ for 2 hours, and roasting the dried powder in air at 650 ℃ for 2 hours to obtain powder A containing active component iron. Then evenly mixing the powder A and adding 7 percent of AL 2 O 3 The adhesive is ball-milled for 15min, then 150g of deionized water is added to prepare slurry, ball-milling is carried out for 10min, the slurry is coated on a metal honeycomb carrier after ball milling, the coating amount is 43.15g/L, the coated catalyst is dried in a hot air oven at 80 ℃ for 2h, and the dried catalyst is baked in air at 500 ℃ for 2 h.
(2) The preparation process of the second coating comprises the following steps:
to 11.1g of cerium sol (sol content: 21%) was added 76.5g of ionized water, and after high-speed shearing, the primary particle diameter was 10.1nm, and the cerium sol and 60gCe were mixed 10 Zr 10 Y 5 AL 75 And 33gCe 60 Zr 30 Y 5 La 5 The materials are dried in a baking oven at 120 ℃ for 2 hours after being uniformly mixed; to 0.46g of platinum nitrate (23.5% concentration of platinum solution) was added 72.7g of deionized water, and after stirring uniformly, the mixture was dried in an oven at 150℃for 2 hours, and the dried powder was calcined in air at 650℃for 2 hours to obtain powder B containing platinum as an active component.
Then evenly mixing the powder B and adding 7 percent of AL 2 O 3 The adhesive is ball-milled for 15min, then 150g of deionized water is added to prepare slurry, ball-milling is carried out for 10min, the slurry is coated on a metal honeycomb carrier after ball milling, the coating amount is 51.78g/L, the coated catalyst is dried in a hot air oven at 80 ℃ for 2h, and the dried catalyst is baked in air at 500 ℃ for 2 h.
(3) The preparation process of the third coating comprises the following steps:
to 4.09g of cerium sol (sol content: 21%) was added 43.5g of ionized water, and after high-speed shearing, the primary particle diameter was 10.2nm, and the cerium sol and 30gCe were mixed 10 Zr 10 Y 5 Al 75 And 27.23gCe 60 Zr 30 Y 5 La 5 The materials are dried in a baking oven at 120 ℃ for 2 hours after being uniformly mixed; 41.3g of deionized water was added to 4.87g of platinum nitrate (23.5% of platinum solution), and after stirring uniformly, the mixture was dried in an oven at 150℃for 2 hours, and the dried powder was calcined in air at 650℃for 2 hours to give powder C containing platinum as an active component.
18g of ionized water was added to 3.57g of zirconium sol (sol content: 15%) and the cerium sol and 35.7g of Ce were sheared at high speed to a primary particle size of 10.4nm 10 Zr 80 Y 10 The materials are dried in a baking oven at 120 ℃ for 2 hours after being uniformly mixed; 17g of deionized water was added to 2.72g of rhodium nitrate (rhodium solution concentration: 10.5%) and stirred uniformly, followed by drying in an oven at 150℃for 2 hours, and the dried powder was calcined at 650℃in air for 2 hours to give powder D containing rhodium as an active component.
Then evenly mixing the powder C and the powder D, and adding 7 percent of AL 2 O 3 The adhesive is ball-milled for 15min, then 150g of deionized water is added to prepare slurry, ball-milling is carried out for 10min, the slurry is coated on a metal honeycomb carrier after ball milling, the coating amount is 61.71g/L, the coated catalyst is dried in a hot air oven at 80 ℃ for 2h, and the dried catalyst A-1 is baked in air at 500 ℃ for 2 h.
Example 2
(iron-based catalyst layer + platinum-rhodium-based catalyst layer)
The total amount of the iron-based catalytic layer is 20g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the The noble metal content of the platinum-rhodium base catalytic layer is 25g/ft 3 Precious metal ratio (Pt: pd: rh) =4:0:1;
the platinum noble metal accounts for 89.9% of the total noble metal, the second layer of platinum accounts for 9.7% of the total platinum consumption, and the third layer of platinum accounts for 90.3% of the total platinum consumption;
the total amount of the iron-based catalytic layer is 10g/ft 3 Adjusted to 20g/ft 3 Other preparation procedures were the same as in example 1 to prepare catalyst A-2.
Example 3
(platinum-based catalyst layer + platinum-rhodium-based catalyst layer)
The total amount of the platinum-based catalyst layer was 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the Noble metal ratio (Pt: pd: rh) =19.5:0:5,
the platinum noble metal accounts for 81.1 percent of the total noble metal, the first layer platinum and the second layer platinum account for 9.3 percent of the total platinum consumption, and the third layer platinum accounts for 90.7 percent of the total platinum consumption;
other preparation procedures were the same as in example 2, and the catalyst prepared was A-3.
Example 4
Coating structure: (platinum+iron) -based catalyst layer+ (platinum+iron) -based catalyst layer+platinum-rhodium-based catalyst layer,
the total amount of the (platinum+iron) base catalyst layer is (1.0+5.0) g/ft 3 The total amount of the (platinum+iron) base catalyst layer is (1.0+5.0) g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 25g/ft 3 The catalyst a-4 was prepared in the same manner as in example 1, except that the noble metal ratio (Pt: pd: rh) =4:0:1, the noble metal of platinum was 81.5% of the total noble metal, the first and second layers of platinum were 9.1% of the total amount of platinum, and the third layer of platinum was 90.9% of the total amount of platinum.
Example 5
Coating structure: platinum-based catalytic layer + platinum-rhodium-based catalytic layer;
the total amount of the platinum-based catalyst layer was 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the Noble metal ratio (Pt: pd: rh) =19.5:0:5,
the platinum noble metal accounts for 81.1 percent of the total noble metal, the first layer platinum and the second layer platinum account for 9.3 percent of the total platinum consumption, and the third layer platinum accounts for 90.7 percent of the total platinum consumption;
the primary particle size nanometer size of the sol is controlled to be about 12nm, the first layer adopts 3% praseodymium sol, the second layer adopts 3% praseodymium sol, the third layer replaces cerium sol with 3% praseodymium sol, and zirconium sol with 3% lanthanum sol, and other preparation processes are the same as those of the catalyst A-5 prepared in the embodiment 3.
Example 6
Coating structure: platinum-based catalytic layer+platinum-rhodium-based catalytic layerThe total amount of the platinum-based catalyst layer was 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The ratio of noble metals (Pt: pd: rh) =19.5:0:5, noble metals of platinum accounting for 81.1% of the total noble metals, the first and second layers of platinum accounting for 9.3% of the total amount of platinum, and the third layer of platinum accounting for 90.7% of the total amount of platinum, the primary particle diameter nano-size of the sol was controlled to be about 20nm, and the other preparation processes were the same as in example 3, catalyst a-6 was prepared.
Example 7
Coating structure: platinum-based catalyst layer+platinum-rhodium-based catalyst layer, the total amount of platinum-based catalyst layer being 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 Precious metal ratio (Pt: pd: rh) =19.5:0:5, platinum precious metal accounts for 81.1% of total precious metal, first and second layers of platinum account for 9.3% of total platinum usage, and third layer of platinum accounts for 90.7% of total platinum usage.
60g Ce of the first layer 10 Zr 10 Y 5 AL 75 (15.4 microns) and 33gCe 60 Zr 30 Y 5 La 5 Adjusted to 80gCe 20 Zr 5 Y 5 Al 60 (10 microns) and 13gCe 80 Zr 10 Y 5 La 5 Simultaneously, the roasting temperature is adjusted to 750 ℃ for 2 hours; 60 of the second layer 60gCe 10 Zr 10 Y 5 Al 75 And 33gCe 60 Zr 30 Y 5 La 5 Adjusted to 70gCe 5 Zr 5 Y 5 Al 85 (20 microns) and 23gCe 100 Simultaneously adjusting the roasting temperature to 750 ℃ for 2 hours, and adjusting the Ce of the third layer 10 Zr 80 Y 10 Adjusted to Ce 20 Zr 60 Y 15 La 5 Meanwhile, the roasting temperature is adjusted to 750 ℃ for 2 hours, and other preparation processes are the same as those of the catalyst A-7 prepared in the example 6.
Example 8
Coating structure: platinum-based catalyst layer+platinum-rhodium-based catalyst layer, the total amount of platinum-based catalyst layer being 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 Platinum-rhodium baseThe noble metal content of the catalytic layer is 24.5g/ft 3 Precious metal ratio (Pt: pd: rh) =19.5:0:5, platinum precious metal accounts for 81.1% of total precious metal, first and second layers of platinum account for 9.3% of total platinum usage, and third layer of platinum accounts for 90.7% of total platinum usage.
The coating amount 43.15g/l of the first layer is adjusted to 35g/l by adjusting the loading amount of the noble metal; catalyst A-8 was prepared in the same manner as in example 6 except that the coating amount of the second layer was adjusted to 45g/l and the coating amount of the third layer was adjusted to 61.71 g/l.
Example 9
Coating structure: platinum-based catalyst layer+platinum-rhodium-based catalyst layer, the total amount of platinum-based catalyst layer being 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 ，
Precious metal ratio (Pt: pd: rh) =19.5:0:5, platinum precious metal accounts for 81.1% of total precious metal, first and second layers of platinum account for 9.3% of total platinum consumption, and third layer of platinum accounts for 90.7% of total platinum consumption.
The first, second and third layers of platinum nitrate were adjusted to hexahydroxy platinate diethanolamine by adjusting the precursor of the noble metal, and the other preparation processes were the same as in example 6, to prepare catalyst a-9.
Example 10
Coating structure: platinum-based catalyst layer+platinum-rhodium-based catalyst layer, the total amount of platinum-based catalyst layer being 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 ，
Precious metal ratio (Pt: pd: rh) =19.5:0:5, platinum precious metal accounts for 81.1% of total precious metal, first and second layers of platinum account for 9.3% of total platinum consumption, and third layer of platinum accounts for 90.7% of total platinum consumption.
The first, second and third layers of platinum nitrate were adjusted to 2-hydroxyethylaminoblatinum hydroxide by adjusting the precursor of the noble metal, and the other preparation processes were the same as in example 6, to prepare catalyst A-10.
Example 11
Coating structure: platinum-based catalytic layer+platinum-basedCatalytic layer+platinum-rhodium based catalytic layer, total amount of platinum-based catalytic layer being 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24g/ft 3 The noble metal ratio (Pt: pd: rh) =5:0:1, the noble metal of platinum accounts for 84.6% of the total noble metal, the first and second platinum layers account for 9.1% of the total platinum, and the third platinum layer accounts for 90.9% of the total platinum.
The subsequent BC carrier was adjusted to conventional carrier specifications, the pore size was adjusted from 300/600cpsi to 300cpsi for the cylindrical metal substrate, and the other preparation was the same as in example 10, catalyst A-11.
Example 12
On the basis of example 6, the second layer of catalyst was eliminated and catalyst A-12 was prepared.
Platinum + platinum rhodium in example 6, 12 is platinum+platinum rhodium;
comparative example 1
Coating structure: platinum-based catalytic layer + platinum-rhodium-based catalytic layer;
the total amount of the platinum-based catalyst layer was 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the Precious metal ratio (Pt: pd: rh) =19.5:0:5;
the platinum noble metal accounts for 81.1 percent of the total noble metal, the first layer platinum and the second layer platinum account for 9.3 percent of the total platinum consumption, and the third layer platinum accounts for 90.7 percent of the total platinum consumption;
the primary particle size of the sol was controlled to about 30nm, and the other preparation processes were the same as in example 3, to prepare catalyst BC-1.
Comparative example 2
Coating structure: platinum-based catalytic layer + platinum-rhodium-based catalytic layer;
the total amount of the platinum-based catalyst layer was 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the Precious metal ratio (Pt: pd: rh) =19.5:0:5.
The platinum noble metal accounts for 81.1 percent of the total noble metal, the first layer platinum and the second layer platinum account for 9.3 percent of the total platinum consumption, and the third layer platinum accounts for 90.7 percent of the total platinum consumption;
the primary particle size nanometer size of the sol is controlled to be about 12nm, the first layer adopts 6% praseodymium sol, the second layer adopts 6% praseodymium sol, the third layer replaces cerium sol with 6% praseodymium sol, and zirconium sol with 6% lanthanum sol, and other preparation processes are the same as those of the catalyst BC-2 prepared in the embodiment 3.
Comparative example 3
Preparation of platinum-based catalyst layer with total amount of 1.0g/ft by reference to patent 201210020661.3 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the Precious metal ratio (Pt: pd: rh) =19.5:0:5.
The platinum noble metal accounts for 81.1 percent of the total noble metal, the first layer platinum and the second layer platinum account for 9.3 percent of the total platinum consumption, and the third layer platinum accounts for 90.7 percent of the total platinum consumption; the prepared catalyst BC-3.
Comparative example 4
Preparation of platinum-based catalyst layer with total amount of 1.0g/ft by reference to patent 202010160118.6 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the Precious metal ratio (Pt: pd: rh) =19.5:0:5.
The platinum noble metal accounts for 81.1 percent of the total noble metal, the first layer platinum and the second layer platinum account for 9.3 percent of the total platinum consumption, and the third layer platinum accounts for 90.7 percent of the total platinum consumption; the prepared catalyst BC-4.
Comparative example 5
Coating structure: platinum-based catalytic layer + platinum-rhodium-based catalytic layer;
the total amount of the platinum-based catalyst layer was 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the Noble metal ratio (Pt: pd: rh) =19.5:0:5,
the platinum noble metal accounts for 81.1 percent of the total noble metal, the first layer platinum and the second layer platinum account for 9.3 percent of the total platinum consumption, and the third layer platinum accounts for 90.7 percent of the total platinum consumption;
the primary particle size nanometer size of the sol is controlled to be about 12nm, the first layer adopts 3% praseodymium sol, the second layer adopts 3% praseodymium sol, the third layer replaces cerium sol with 3% praseodymium sol, and zirconium sol with 3% praseodymium sol, and other preparation processes are the same as those of the catalyst BC-5 prepared in the embodiment 5.
Comparative example 6
Coating structure: platinum-based catalyst layer+platinum-rhodium-based catalyst layer, the total amount of platinum-based catalyst layer being 1.0g/ft 3 The total amount of noble metal of the platinum-based catalytic layer is 1.0g/ft 3 The noble metal content of the platinum-rhodium base catalytic layer is 24.5g/ft 3 Precious metal ratio (Pt: pd: rh) =19.5:0:5, platinum precious metal accounts for 81.1% of total precious metal, first and second layers of platinum account for 9.3% of total platinum usage, and third layer of platinum accounts for 90.7% of total platinum usage.
Ce of the third layer 10 Zr 80 Y 10 Adjusted to Ce 60 Zr 30 Y 5 La 5 Meanwhile, the roasting temperature is adjusted to 750 ℃ for 2 hours, and other preparation processes are the same as those of the catalyst BC-6 prepared in the example 1.
Catalysts A-1 to A-12 and BC-1 to BC-6 were mounted on 250CC motorcycles manufactured by a company, and emission tests were performed using the test protocol specified in Euro V. The fresh performance test results are shown in table 3 below.
Table 3 results of emissions test of catalysts on 250CC motorcycles
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The catalyst A-1-12 prepared by the method has good THC and NMHC purification performance.
Catalysts A-9 and BC-2 were mounted on a 250CC motorcycle manufactured by a company, and a chassis endurance test was performed using the test protocol specified in European V, with an endurance mileage of 10000km. The results after durability are shown in table 4 below.
Table 4 results of emissions test of catalysts after durability on 250CC motorcycles
By applying the invention, the improved A-9 catalyst has good durability, the emission value after durability is controlled within 80% of the standard limit value, and a larger margin is provided.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (6)
1. The three-way catalyst is characterized by comprising a metal matrix and at least two layers of coating layers coated on the metal matrix, wherein the coating layers comprise a bottom layer coating layer and a top layer coating layer which are sequentially coated on the metal matrix;
the bottom coating takes transition metal and/or noble metal platinum as an active component,
the bottom layer coating is prepared by mixing sol A with a first catalytic material, drying, mixing with a precursor solution containing active ingredients to prepare bottom layer slurry, and coating, drying and roasting;
the first catalytic material comprises a cerium zirconium material A and a cerium zirconium aluminum material; the cerium-zirconium material A comprises CeO with Ce content not less than 40wt percent 2 The method comprises the steps of carrying out a first treatment on the surface of the The second catalytic material comprises a cerium-zirconium material A, a cerium-zirconium material B and a cerium-zirconium-aluminum material; the cerium-zirconium material B comprises CeO with the Ce content not exceeding 40 percent 2 The method comprises the steps of carrying out a first treatment on the surface of the The cerium-zirconium-aluminum material comprises CeO with cerium content of 5-20% 2 ZrO with zirconium content of 5-10% 2 1 to 5 percent of La 2 O 3 、Y 2 O 3 The balance of Al 2 O 3 The method comprises the steps of carrying out a first treatment on the surface of the The grain size range of the cerium-zirconium-aluminum material is 6-50 mu m;
the top layer coating takes metal platinum and rhodium as active components,
the top layer coating is prepared by mixing a second catalytic material with sol A or sol B respectively, drying, mixing with precursor solution containing corresponding active components to prepare top layer slurry, coating, drying and roasting;
in the three-way catalyst, the total noble metal content is 10-50g/ft 3 Wherein, the content of the metal platinum accounts for 50% -95% of the total noble metal content, and the balance is noble metal rhodium; the content of the transition metal in the bottom coating is 0-100g/ft 3 The method comprises the steps of carrying out a first treatment on the surface of the The content of platinum in the bottom layer coating is 0.1-10% of the total content of platinum, and the content of platinum in the top layer coating is 90-99.9% of the total content of platinum;
the particle size range of the sol A and the sol B is not more than 25nm;
the sol A comprises any one or a combination of a plurality of cerium sol and praseodymium sol;
the sol B comprises any one or a combination of a plurality of zirconium sol, neodymium sol, lanthanum sol and yttrium sol.
2. The three-way catalyst according to claim 1, wherein the washcoat comprises a first washcoat layer and a second washcoat layer from bottom to top, the first washcoat layer being a transition metal-based catalyst layer, or a platinum-based catalyst layer, or a transition metal-platinum-based catalyst layer; the second coating is a platinum-based catalytic layer, or a transition metal-platinum-based catalytic layer.
3. A method for preparing a three-way catalyst according to any one of claims 1 to 2, wherein slurries corresponding to each coating layer are prepared according to the coating structure of the three-way catalyst, and then the slurries of each coating layer are coated on a metal honeycomb carrier in a separated manner to obtain the three-way catalyst, and each layer of slurry is coated on the carrier, and then the next coating layer of slurry coating is performed after drying and roasting;
the slurry of the bottom coating is prepared in the following manner:
step 1.1: adding deionized water into the sol A, uniformly mixing with the cerium-zirconium material A and/or the cerium-zirconium-aluminum material after shearing, and drying to obtain powder A; the particle size range of the sol A after shearing is not more than 25nm;
step 1.2: adding deionized water into precursor solution of noble metal and/or transition metal, stirring uniformly, mixing with powder A, stirring, and drying; roasting the dried mixed powder to obtain powder A containing active components;
step 1.3: adding a binder into the powder A containing the active components obtained in the step 1.2, ball milling, adding deionized water, and continuing ball milling to obtain a bottom layer slurry;
the slurry of the top coat is prepared as follows:
preparing powder B containing noble metal platinum and powder C containing noble metal rhodium respectively, uniformly mixing the powder B and the powder C, adding a binder, ball-milling, adding deionized water, and continuing ball-milling to obtain the top-layer slurry.
4. A process for the preparation of a three-way catalyst according to claim 3, characterized in that the powder C containing the noble metal rhodium is prepared in the following manner:
step 2.1: adding deionized water into the sol B, uniformly mixing with the cerium-zirconium material B after shearing, and drying to obtain powder C; the particle size range of the sol after shearing is not more than 25nm;
step 2.2: adding deionized water into precursor solution of noble metal rhodium, stirring uniformly, mixing with powder C, stirring, and drying; and roasting the mixed powder to obtain the powder C containing the noble metal rhodium.
5. The method for preparing a three-way catalyst according to claim 3, wherein the preparation of the noble metal platinum-containing powder B is similar to the preparation of the noble metal platinum-containing powder a; the specific steps are as follows:
step 3.1: adding deionized water into the sol A, uniformly mixing with a cerium-zirconium-aluminum material and/or a cerium-zirconium material A after high-speed shearing, and drying to obtain powder B; the particle size range of the sol A after shearing is not more than 25nm;
step 3.2: adding deionized water into precursor solution of noble metal platinum, mixing with powder B, stirring, drying, and roasting the dried powder B to obtain powder B containing noble metal platinum.
6. The method for preparing a three-way catalyst according to claim 5, wherein the coating amount of the first coating layer and the second coating layer is 30-60g/L, respectively, and the coating amount of the third coating layer is 40-80 g/L.
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