CN117654567B - Pt-Ru three-way catalyst and preparation method thereof - Google Patents
Pt-Ru three-way catalyst and preparation method thereof Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 61
- 229910002848 Pt–Ru Inorganic materials 0.000 title claims abstract description 17
- 238000002360 preparation method Methods 0.000 title abstract description 6
- 238000000576 coating method Methods 0.000 claims abstract description 236
- 239000011248 coating agent Substances 0.000 claims abstract description 234
- 230000003197 catalytic effect Effects 0.000 claims abstract description 23
- 239000000463 material Substances 0.000 claims description 125
- 239000000919 ceramic Substances 0.000 claims description 56
- 238000011068 loading method Methods 0.000 claims description 43
- 239000011247 coating layer Substances 0.000 claims description 34
- 239000006255 coating slurry Substances 0.000 claims description 31
- 239000011230 binding agent Substances 0.000 claims description 28
- 238000001035 drying Methods 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 23
- 229910002651 NO3 Inorganic materials 0.000 claims description 22
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 22
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 21
- 229910052684 Cerium Inorganic materials 0.000 claims description 21
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 19
- 229910052782 aluminium Inorganic materials 0.000 claims description 19
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 19
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 18
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 18
- 150000003863 ammonium salts Chemical class 0.000 claims description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 15
- 239000001301 oxygen Substances 0.000 claims description 15
- 229910052760 oxygen Inorganic materials 0.000 claims description 15
- 229910052878 cordierite Inorganic materials 0.000 claims 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 claims description 14
- 239000002243 precursor Substances 0.000 claims description 14
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 12
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 12
- 229910052726 zirconium Inorganic materials 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 11
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 238000000498 ball milling Methods 0.000 claims description 6
- 239000011148 porous material Substances 0.000 claims description 4
- 239000000969 carrier Substances 0.000 claims description 3
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 claims description 3
- 229910052863 mullite Inorganic materials 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 239000000084 colloidal system Substances 0.000 claims 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 abstract description 18
- 229910002091 carbon monoxide Inorganic materials 0.000 abstract description 18
- 229930195733 hydrocarbon Natural products 0.000 abstract description 12
- 150000002430 hydrocarbons Chemical class 0.000 abstract description 12
- 239000004215 Carbon black (E152) Substances 0.000 abstract description 11
- 238000000746 purification Methods 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 65
- 230000000052 comparative effect Effects 0.000 description 21
- 239000000843 powder Substances 0.000 description 20
- 239000002002 slurry Substances 0.000 description 19
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 18
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 16
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 11
- 239000007789 gas Substances 0.000 description 11
- 239000000243 solution Substances 0.000 description 10
- 238000002156 mixing Methods 0.000 description 9
- 239000010948 rhodium Substances 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 229910052697 platinum Inorganic materials 0.000 description 8
- 229910021529 ammonia Inorganic materials 0.000 description 7
- RCFVMJKOEJFGTM-UHFFFAOYSA-N cerium zirconium Chemical compound [Zr].[Ce] RCFVMJKOEJFGTM-UHFFFAOYSA-N 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229910052761 rare earth metal Inorganic materials 0.000 description 5
- 229910052703 rhodium Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000002131 composite material Substances 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 229910052763 palladium Inorganic materials 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
- -1 rare earth modified cerium-zirconium Chemical class 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 3
- 238000006555 catalytic reaction Methods 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
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- 231100000719 pollutant Toxicity 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
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- 230000033116 oxidation-reduction process Effects 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- GTCKPGDAPXUISX-UHFFFAOYSA-N ruthenium(3+);trinitrate Chemical compound [Ru+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O GTCKPGDAPXUISX-UHFFFAOYSA-N 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 210000003169 central nervous system Anatomy 0.000 description 1
- 239000013025 ceria-based material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 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
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Abstract
The invention provides a Pt-Ru three-way catalyst and a preparation method thereof, and relates to the technical field of catalysts. The Pt-containing coating is treated in a specific atmosphere, so that the catalytic activity of the catalyst per unit can be improved, the purification efficiency of hydrocarbon, oxynitride and carbon monoxide is improved, the problem of exceeding NH 3 emission in automobile exhaust can be solved without adding an ammoxidation catalyst, the ammoxidation catalyst at the rear end of a three-way catalyst is avoided, a post-treatment system is simplified, and the production cost of the post-treatment system is remarkably reduced.
Description
Technical Field
The invention relates to the technical field of catalysts, in particular to a Pt-Ru three-way catalyst and a preparation method thereof.
Background
In an automobile adopting equivalent ratio combustion, the tail gas contains pollutants such as Hydrocarbon (HC), nitrogen oxide (NO X), carbon monoxide (CO) and the like, and an integrated aftertreatment system consisting of a three-way catalyst and an ammonia oxidation catalyst is generally adopted at present. The three-way catalyst is close to the air inlet end, HC, NO X and CO can be converted into nontoxic carbon dioxide (CO 2), water (H 2 O) and nitrogen (N 2), but in the tail gas purification process, side reactions CO/HC+H 2O+NO→NH3+CO2 occur, so that the ammonia emission in the tail gas treated by the three-way catalyst is obviously increased, and the ammonia is a toxic substance with a strong stimulation effect on the central nervous system of a human body; the ammonia oxidation catalyst is close to the air outlet end, and can oxidize ammonia (NH 3) generated by the three-way catalyst into nitrogen N 2 and H 2 O.
Three-way catalysts commonly used in the prior art, especially for natural gas vehicles, typically have palladium (Pd) and rhodium (Rh) as the active components and platinum (Pt) as the active components. The Pd content is highest in the whole aftertreatment system, the Pt and Rh contents are close, but the prices of Pd and Rh are continuously increased at present, so that the cost of the aftertreatment system is higher and higher, and the activity of the Pt ammoxidation catalyst is not high.
Therefore, there is a need to develop an automobile exhaust aftertreatment system that is excellent in performance and low in cost.
Disclosure of Invention
In view of the above-mentioned drawbacks or shortcomings in the prior art, the present invention provides a Pt-Ru three-way catalyst and a method for preparing the same.
The invention aims at providing a Pt-Ru three-way catalyst, which comprises a honeycomb ceramic carrier, and a first coating and a second coating which are coated on carrier pore channels, wherein the first coating and the second coating are coated on the honeycomb ceramic carrier in a layered or segmented manner;
The first coating is a Pt-containing coating, and the second coating is a Ru-containing coating;
the Pt-containing coating is treated for 5-20 hours at 600-900 ℃ in a specific atmosphere, wherein the specific atmosphere comprises 0-15 vol.% of water, 15-25 vol.% of oxygen and 60-85 vol.% of nitrogen.
Wherein the layered coating comprises: a first coating is first applied to the honeycomb ceramic support and a second coating is then applied to the first coating.
The step coating comprises the following steps: and coating a first coating on the front section of the honeycomb ceramic carrier, which is close to the air inlet end, and coating a second coating on the rear section of the honeycomb ceramic carrier, which is close to the air outlet end.
Preferably, the loading amount of Pt is 30-70 g/ft 3.
Preferably, the Ru loading amount is 3-20 g/ft 3.
Preferably, when the sectional coating is adopted, the ratio of the coating length of the first coating to the coating length of the second coating is 5-8: 2-5.
Preferably, the first coating comprises Pt and a first catalytic material comprising a first cerium-based material.
Preferably, the second coating comprises Ru and a second catalytic material, the second catalytic material comprising one or more of a second cerium-based material and an aluminum-based material.
The second object of the invention is to provide a preparation method of the Pt-Ru three-way catalyst, which comprises the following steps:
a, preparing a first coating material:
the method comprises the steps of firstly loading a precursor solution of Pt on a first catalytic material, then drying, roasting, and then treating in a specific atmosphere to obtain the first coating material.
B, preparing a second coating material:
and firstly, loading a precursor solution of Ru on a second catalytic material, and then drying and roasting to obtain a second coating material.
C forms a first coating:
First, ball milling a first coating material, a first binder and water to obtain first coating slurry, then coating the first coating slurry on a honeycomb ceramic carrier, drying, and roasting to form a first coating.
The first coating slurry is coated on the whole section of the honeycomb ceramic carrier or the front section of the carrier near the air inlet end.
D forming a second coating:
Firstly, ball milling a second coating material, a second binder and water to obtain second coating slurry, then coating the second coating slurry on the first coating or the rear section of the honeycomb ceramic carrier close to the air outlet end, drying and roasting to form a second coating.
Preferably, the mass content of Pt in the first coating material is 0.9-2.5%.
Preferably, the mass content of Ru in the second coating material is 0.1-0.7%.
Preferably, the solid content of the first coating slurry and the second coating slurry is 30% -40% independently.
Preferably, the mass ratio of the first coating material to the first binder is 85-97: 3-15.
Preferably, the mass ratio of the second coating material to the second binder is 85-97: 3-15.
Preferably, the precursor of Pt includes one or more of nitrate, acetate, hydrochloride, or ammonium salts of Pt.
Preferably, the precursor of Ru comprises one or more of nitrate, acetate, hydrochloride or ammonium salts of Ru.
Preferably, the first binder and the second binder each independently include one or more of an aluminum sol, a silica sol, or a zirconium gel.
Preferably, the honeycomb ceramic carrier comprises one or more of cordierite, mullite or silicon carbide honeycomb ceramic carriers.
The method comprises the steps of coating a first coating and a second coating in pore channels of a honeycomb ceramic carrier, wherein the first coating is a Pt-containing coating and is used for converting hydrocarbon and carbon monoxide in tail gas into CO 2 and H 2 O, and simultaneously converting nitrogen oxides in the tail gas into N 2 and NH 3; the second coating is a Ru-containing coating, is mainly used as an ammonia decomposition catalyst coating and is used for decomposing a byproduct NH 3 generated by the Pt-containing coating, and directly decomposing NH 3 into N 2 and H 2, and the catalytic activity of the catalyst is higher.
In addition, after the Pt-containing coating material is treated in a specific atmosphere, high-activity surface oxygen and more oxygen vacancies are formed around Pt and Ce, so that the oxidation-reduction performance of the Pt-containing catalyst can be improved, the catalytic activity is improved, and the purification efficiency of the coating on hydrocarbon, oxynitride and carbon monoxide is improved.
According to the invention, the problem of exceeding NH 3 emission standard in automobile exhaust can be solved without adding an ammoxidation catalyst, and the aftertreatment system is simplified. Compared with the current mainstream aftertreatment system of the equivalent ratio combustion automobile, the invention replaces expensive Pd and Rh with low-cost Pt and Ru, omits an ammoxidation catalyst at the rear end of the three-way catalyst, and obviously reduces the production cost of the aftertreatment system.
Drawings
FIG. 1 is a graph showing the results of H 2 -TPR (temperature programmed reduction) tests for the catalysts of example 1 and comparative example 1;
FIG. 2 is a graph showing the conversion of CH 4 during a three-way catalytic reaction for the catalysts of comparative examples 1-3 and examples 1-2;
FIG. 3 is a graph of NO conversion during a three-way catalytic reaction for the catalysts of comparative examples 1-3 and examples 1-2;
Fig. 4 is a graph showing the concentration change of NH 3 during the three-way catalytic reaction of the catalysts of comparative examples 1-3 and examples 1-2.
Detailed Description
In the following description, certain specific details are included to provide a thorough understanding of various disclosed embodiments. One skilled in the relevant art will recognize, however, that the embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc.
Unless otherwise required by the present invention, the words "comprise" and "comprising" are to be interpreted in an open, inclusive sense, i.e. "including but not limited to.
Reference throughout this specification to "one embodiment" or "an embodiment" or "one preferred embodiment" or "certain embodiments" means that a particular reference element, structure, or feature described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" or "in a preferred embodiment" or "in certain embodiments" appearing in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular elements, structures, or features may be combined in any suitable manner in one or more embodiments.
According to a first aspect of the present invention, there is provided a Pt-Ru three-way catalyst comprising a honeycomb ceramic support and first and second coating layers applied to the pores of the support, the first and second coating layers being layered or staged on the honeycomb ceramic support.
In the invention, the honeycomb ceramic carrier comprises one or more of cordierite, mullite or silicon carbide honeycomb ceramic carriers and is used for carrying the first coating and the second coating.
The first coating is a Pt-containing coating, and the second coating is a Ru-containing coating;
the Pt-containing coating is treated for 5-20 hours at 600-900 ℃ in a specific atmosphere, wherein the specific atmosphere comprises 0-15 vol.% of water, 15-25 vol.% of oxygen and 60-85 vol.% of nitrogen.
In the present invention, as shown in fig. 1, a new reduction peak appears in the H 2 -TPR spectrum of the catalyst of example 1 subjected to the specific atmosphere treatment, and as shown in peak 2 in fig. 1, the appearance of the peak indicates that after the Pt-containing coating material is subjected to the specific atmosphere treatment, high-activity surface oxygen is formed around Pt and Ce, so that the oxidation-reduction performance of the Pt-containing catalyst can be improved, and the purification efficiency of the coating on hydrocarbon, oxynitride and carbon monoxide can be improved.
Wherein the layered coating comprises: a first coating is first applied to the honeycomb ceramic support and a second coating is then applied to the first coating.
In the present invention, when a layered coating method is used, a first coating layer is first applied on the entire honeycomb ceramic carrier, and then a second coating layer is applied outside the entire first coating layer. As the exhaust passes through the first coating, hydrocarbons and carbon monoxide in the exhaust are converted to CO 2 and H 2 O, while nitrogen oxides in the exhaust are converted to N 2 and NH 3. Then, when the exhaust gas passes through the second coating layer again, NH 3 generated in the first coating layer is decomposed into N 2 and H 2.
The step coating comprises the following steps: and coating a first coating on the front section of the honeycomb ceramic carrier, which is close to the air inlet end, and coating a second coating on the rear section of the honeycomb ceramic carrier, which is close to the air outlet end.
In the present invention, when the staged coating method is used, the sum of the coating lengths of the first coating layer and the second coating layer is equal to the total length of the honeycomb ceramic carrier. The first coating is coated on the front section of the honeycomb ceramic carrier near the air inlet end, the automobile exhaust firstly passes through the first coating, hydrocarbon and carbon monoxide in the exhaust are converted into CO 2 and H 2 O, and nitrogen oxides in the exhaust are simultaneously converted into N 2 and NH 3. The second coating is coated on the rear section of the honeycomb ceramic carrier near the air outlet end, and NH 3 in the tail gas treated by the first coating is decomposed into N 2 and H 2.
Preferably, the first coating and the second coating are coated on the honeycomb ceramic carrier in a segmented manner, which is more beneficial to reducing the emission amount of NH 3. This is because when the layered coating is used, when the second coating layer is applied on the first coating layer, the second coating layer inevitably partially penetrates into the first coating layer, so that Pt in the first coating layer and Ru in the second coating layer are intermixed, thereby affecting the catalytic effect of Ru.
In some embodiments of the present invention, the Pt loading is 30-70 g/ft 3, for example 30g/ft3、35g/ft3、40g/ft3、45g/ft3、50g/ft3、55g/ft3、60g/ft3、65g/ft3 or 70g/ft 3, if the Pt loading is lower than 30 g/ft 3, the conversion efficiency of hydrocarbon, nitrogen oxide and carbon monoxide is low, and if the Pt loading is higher than 70g/ft 3, the catalyst cost is higher.
Ru loading is 3-20 g/ft 3, for example 3g/ft3、4g/ft3、6g/ft3、8g/ft3、10g/ft3、12g/ft3、14g/ft3、16g/ft3、18g/ft3 or 20g/ft 3, if Ru loading is lower than 3 g/ft 3, ammonia removal rate is lower, and if Ru loading is higher than 20g/ft 3, catalyst cost is higher.
In some embodiments of the present invention, when the segmented coating is used, the ratio of the coating length of the first coating layer to the coating length of the second coating layer is 5 to 8: 2-5.
Specifically, the first coating layer has a coating length of 50% -80%, such as 50%, 55%, 60%, 65%, 70%, 75% or 80%, and the second coating layer has a coating length of 20% -50%, such as 20%, 25%, 30%, 35%, 40%, 45% or 50%, of the carrier length. When the coating length of the first coating layer is less than 50% of the length of the carrier, the removal rate of hydrocarbon, nitrogen oxide and carbon monoxide by the Pt-Ru three-way catalyst is reduced, and when the coating length of the second coating layer is less than 20% of the length of the carrier, the residual ammonia gas amount in the tail gas is increased.
In some embodiments of the invention, the first coating comprises Pt and a first catalytic material comprising a first cerium-based material.
Specifically, in the present invention, pt is first supported on the first catalytic material and then coated on the honeycomb ceramic carrier to form the first coating layer.
In the invention, the mass content of cerium in the first cerium-based material is 60-90%, and the specific surface area of the first cerium-based material is more than 100m 2/g.
The mass content of cerium in the first cerium-based material in the present invention is, for example, 60%, 65%, 70%, 75%, 80%, 85% or 90%. The specific surface area of the mono-cerium-based material is 100m2/g、110m2/g、120m2/g、130m2/g、140m2/g、150m2/g、160m2/g、180m2/g、200m2/g、220m2/g or 250m 2/g, for example.
Preferably, the first cerium-based material comprises one or more of cerium-zirconium solid solution or rare earth modified cerium-zirconium composite oxide.
In some embodiments of the invention, the second coating comprises Ru and a second catalytic material comprising one or more of a second cerium-based material or an aluminum-based material.
In the invention, the mass content of cerium in the second cerium-based material is 60-90%, and the specific surface area of the second cerium-based material is more than 100m 2/g.
The mass content of cerium in the second cerium-based material in the present invention is, for example, 60%, 65%, 70%, 75%, 80%, 85% or 90%. The specific surface area of the ceria-based material is 100m2/g、110m2/g、120m2/g、130m2/g、140m2/g、150m2/g、160m2/g、180m2/g、200m2/g、220m2/g or 250m 2/g, for example.
Preferably, the second cerium-based material comprises one or more of cerium-zirconium solid solution or rare earth modified cerium-zirconium composite oxide.
Preferably, the aluminum-based material comprises one or more of alumina or rare earth modified alumina.
According to a second aspect of the present invention, there is provided a method for preparing a Pt-Ru three-way catalyst, the method comprising:
a, preparing a first coating material:
the method comprises the steps of firstly loading a precursor solution of Pt on a first catalytic material, then drying, roasting, and then treating in a specific atmosphere to obtain the first coating material.
Specifically, a precursor solution of Pt is firstly loaded on a first catalytic material through an impregnation method, then dried for 3-5 hours at 100-120 ℃, then baked for 2-5 hours at 500-600 ℃, and then subjected to specific atmosphere treatment to obtain a first coating material. The specific atmosphere treatment is to treat the mixture for 5 to 20 hours at 600 to 900 ℃ in an atmosphere of 0 to 15 percent of water, 15 to 25 percent of oxygen and 60 to 85 percent of nitrogen by volume.
Preferably, the mass content of Pt in the first coating material is 0.9-2.5%, for example, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4% or 2.5%.
B, preparing a second coating material:
and firstly, loading a precursor solution of Ru on a second catalytic material, and then drying and roasting to obtain a second coating material.
Specifically, a precursor solution of Ru is firstly loaded on a second catalytic material through an impregnation method, then dried for 3-5 h at 100-120 ℃, and then baked for 2-5 h at 500-600 ℃ to obtain a second coating material.
Preferably, the mass content of Ru in the second coating material is 0.1-0.7%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65% or 0.7%.
C forms a first coating:
First, ball milling a first coating material, a first binder and water to obtain first coating slurry, then coating the first coating slurry on a honeycomb ceramic carrier, drying, and roasting to form a first coating.
The first coating slurry is coated on the whole section of the honeycomb ceramic carrier or the front section of the carrier near the air inlet end.
Specifically, when the first coating and the second coating are applied in a layered coating, the first coating slurry is applied to the entire section of the honeycomb ceramic carrier; when the first coating and the second coating are applied in the form of a staged application, the first coating slurry is applied to the front section of the honeycomb ceramic support near the air inlet end.
Preferably, the mass ratio of the first coating material to the first binder is 85-97: 3-15.
Specifically, the mass of the first coating material is 85% -97% of the sum of the mass of the first coating material and the mass of the first binder, for example 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96% or 97%. The mass of the first binder is 3% -15% of the sum of the mass of the first coating material and the mass of the first binder, for example 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.
Preferably, the solid content of the first coating slurry is 30% -40%, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.
Preferably, the precursor of Pt is a soluble salt of Pt, including one or more of nitrate, acetate, hydrochloride or ammonium salts of Pt. For example, the nitrate, acetate, hydrochloride, ammonium salt, nitrate and acetate, nitrate and hydrochloride, nitrate and ammonium salt, nitrate, acetate and hydrochloride, nitrate, acetate and ammonium salt, nitrate, hydrochloride and ammonium salt, acetate, hydrochloride and ammonium salt, or a combination of nitrate, acetate, hydrochloride and ammonium salt of Pt.
Preferably, the first binder comprises one or more of an aluminum sol, a silica sol or a zirconium gel. For example, aluminum sol, silica sol, zirconium sol, aluminum sol and silica sol, aluminum sol and zirconium sol, silica sol and zirconium sol, or a combination of aluminum sol, silica sol and zirconium sol.
Preferably, after the first coating slurry is coated on the honeycomb ceramic carrier, the honeycomb ceramic carrier is dried for 3-5 hours at 100-120 ℃, and then baked for 2-5 hours at 500-600 ℃ to form the first coating.
D forming a second coating:
Firstly, ball milling a second coating material, a second binder and water to obtain second coating slurry, then coating the second coating slurry on the first coating or the rear section of the honeycomb ceramic carrier close to the air outlet end, drying and roasting to form a second coating.
Specifically, when the first coating layer and the second coating layer are coated in the form of layered coating, the second coating slurry is coated on the first coating layer coated on the entire section of the honeycomb ceramic carrier in the step C; when the first coating and the second coating are coated in a sectional coating mode, the first coating slurry is coated on the front carrier section of the honeycomb ceramic carrier, which is close to the air inlet end, and the second coating slurry is coated on the rear carrier section of the honeycomb ceramic carrier, which is close to the air outlet end.
Preferably, the mass ratio of the second coating material to the second binder is 85-97: 3-1.
Specifically, the mass of the second coating material is 85% -97% of the sum of the mass of the second coating material and the mass of the second binder, for example 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96% or 97%. The mass of the two binders is 3% -15% of the sum of the mass of the second coating material and the mass of the second binder, for example 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.
Preferably, the solid content of the second coating slurry is 30% -40%, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.
Preferably, the precursor of Ru is a soluble salt of Ru, including one or more of nitrate, acetate, hydrochloride or ammonium salts of Ru. For example, nitrate, acetate, hydrochloride, ammonium salt, nitrate and acetate, nitrate and hydrochloride, nitrate and ammonium salt, nitrate, acetate and hydrochloride, nitrate, acetate and ammonium salt, nitrate, hydrochloride and ammonium salt, acetate, hydrochloride and ammonium salt, or a combination of nitrate, acetate, hydrochloride and ammonium salt.
Preferably, the second binder comprises one or more of an aluminum sol, a silica sol or a zirconium gel. For example, aluminum sol, silica sol, zirconium sol, aluminum sol and silica sol, aluminum sol and zirconium sol, silica sol and zirconium sol, or a combination of aluminum sol, silica sol and zirconium sol.
Preferably, the second coating slurry is coated on the first coating or the rear section of the honeycomb ceramic carrier close to the air outlet end, and then dried for 3-5 hours at 100-120 ℃, and then baked for 2-5 hours at 500-600 ℃ to form the second coating.
In the present invention, in the above A, B, C, D four steps, the sequence of step a and step B is not fixed, and the sequence of step B and step C is not fixed. That is, the preparation method may sequentially include A, B, C, D steps, B, A, C, D steps, A, C, B, D steps, or steps a and B or steps B and C may be performed simultaneously.
Example 1
A9.85 g of cerium-zirconium solid solution powder was added to a platinum nitrate solution containing 0.15g of Pt, rapidly stirred uniformly, then left to stand for 3 hours, then dried at 110℃for 4 hours, then calcined at 550℃for 3 hours, and then placed in an atmosphere containing 10vol.% of water, 20vol.% of oxygen and 70vol.% of nitrogen, and treated at 800℃for 10 hours to obtain a first coating material powder, wherein the Pt content in the first coating material was 1.5wt%.
And B, adding 9.95g of rare earth modified cerium-zirconium composite oxide into a ruthenium nitrate solution containing 0.05g of Ru, rapidly and uniformly stirring, standing for 3 hours, drying at 110 ℃ for 4 hours, and roasting at 550 ℃ for 3 hours to obtain second coating material powder with Ru content of 0.5 wt%.
And C, mixing 95 parts by weight of a first coating material, 5 parts by weight of aluminum sol and a water ball mill into a first coating material slurry with the solid content of 35%, coating the first coating material slurry on the front section of an air inlet end carrier of the cordierite ceramic honeycomb carrier, wherein the length of the front section of the carrier is 70% of the length of the carrier, drying for 4 hours at 110 ℃, and roasting for 3 hours at 550 ℃ to form a first coating, wherein the loading amount of Pt is 60g/ft 3.
And D, mixing 95 parts by weight of a second coating material, 5 parts by weight of aluminum sol and a water ball mill into second coating material slurry with the solid content of 35%, and then coating the second coating material slurry on the rear section of the carrier after the first coating is formed in the step C, namely the rear section of the carrier at the air outlet end of the cordierite ceramic honeycomb carrier, wherein the length of the rear section of the carrier is 30% of the length of the carrier, drying the carrier for 4 hours at 110 ℃, and roasting the carrier for 3 hours at 550 ℃ to form a second coating, wherein the load of Ru is 10g/ft 3.
That is, example 1 is a catalyst obtained by sectionally coating a first coating layer and a second coating layer.
Comparative example 1
A, adding 9.85g of cerium-zirconium solid solution powder into a platinum nitrate solution containing 0.15g of Pt, rapidly and uniformly stirring, standing for 3 hours, then drying at 110 ℃ for 4 hours, and then roasting at 550 ℃ for 3 hours to obtain a first coating material powder, wherein the Pt content in the first coating material is 1.5wt%.
That is, the first coating material is not treated with a specific atmosphere in step a.
Step B, C, D is the same as in example 1.
That is, comparative example 1 is a catalyst in which the first coating layer and the second coating layer were coated in stages, and the first coating layer was not treated with a specific atmosphere, in which the Pt loading was 60g/ft 3, and the Ru loading was 10g/ft 3.
Example 2
Step A, B of example 2 is the same as example 1, step C, D is as follows:
And C, mixing 95 parts by weight of the first coating material and 5 parts by weight of the first binder through a water ball mill to obtain a first coating material slurry with the solid content of 35%, coating the whole cordierite ceramic honeycomb carrier with the first coating material slurry, drying at 110 ℃ for 4 hours, and roasting at 550 ℃ for 3 hours to form a first coating, wherein the loading of Pt is 60g/ft 3.
And D, mixing 95 parts by weight of a second coating material, 5 parts by weight of a second binder and a water ball mill into second coating material slurry with the solid content of 35%, coating the second coating material slurry on the first coating formed in the step C, drying the first coating for 4 hours at 110 ℃, and roasting the second coating at 550 ℃ for 3 hours to form a second coating, wherein the Ru loading amount is 10g/ft 3.
That is, example 2 is a catalyst obtained by layering a first coating layer and a second coating layer.
Comparative example 2
A the same method as in example 1 was used to obtain a first coating material powder having a Pt content of 2 wt%.
B A second coating material powder having a Ru content of 1% by weight was obtained in the same manner as in example 1.
And C, mixing 71.25 parts by weight of the first coating material powder, 23.75 parts by weight of the second coating material powder, 5 parts by weight of aluminum sol and a water ball mill to obtain slurry with the solid content of 35%, coating the slurry on a cordierite ceramic honeycomb carrier, drying the slurry at 110 ℃ for 4 hours, and roasting the dried slurry at 550 ℃ for 3 hours to obtain the single-layer coated catalyst after mixing the first coating material powder and the second coating material powder.
In comparative example 2, the Pt loading was 60g/ft 3 and the Ru loading was 10g/ft 3.
Comparative example 3
A, adding 9.85g of cerium-zirconium solid solution powder into a mixed solution of platinum nitrate and palladium nitrate containing 0.1g of Pt and 0.05g of Pd, rapidly and uniformly stirring, standing for 3 hours, drying at 110 ℃ for 4 hours, and roasting at 550 ℃ for 3 hours to obtain first coating material powder with the Pt content of 1wt% and the Pd content of 0.5 wt%.
And B, adding 9g of cerium-zirconium solid solution powder into a platinum nitrate solution containing 0.1g of Pt, rapidly and uniformly stirring, standing for 3 hours, then drying at 110 ℃ for 4 hours, and then roasting at 550 ℃ for 3 hours to obtain second material powder, wherein the Pt content in the second material is 1wt%.
9.95G of rare earth modified cerium-zirconium composite oxide is added into a mixed solution of rhodium nitrate and ruthenium nitrate containing 0.04gRh g and 0.01g Ru, and after being rapidly and uniformly stirred, the mixed solution is stood for 3 hours, then dried for 4 hours at 110 ℃, and then baked for 3 hours at 550 ℃, third material powder is obtained, wherein the content of Rh in the third material is 0.4 percent, and the content of Ru in the third material is 0.1 percent by weight.
Mixing the second material and the third material may be used to prepare the second coating material.
And C, mixing 95 parts by weight of a first coating material, 5 parts by weight of a first binder and a water ball mill into a first coating material slurry with the solid content of 35%, coating the first coating material slurry on the whole cordierite ceramic honeycomb carrier, drying at 110 ℃ for 4 hours, and roasting at 550 ℃ for 3 hours to form a first coating, wherein the loading of Pt in the first coating is 20g/ft 3, and the loading of Pd in the first coating is 10g/ft 3.
And D, mixing 57 parts by weight of a second material, 38 parts by weight of a third material, 5% by weight of a first binder and a water ball mill to obtain a second coating material slurry with the solid content of 35%, coating the second coating material slurry on the first coating, drying at 110 ℃ for 4 hours, and roasting at 550 ℃ for 3 hours to form the first coating, wherein in the second coating, the Pt load is 30g/ft 3, the Rh load is 8g/ft 3, and the Ru load is 2g/ft 3.
In comparative example 3, the total loading of Pt was 50g/ft 3, the loading of Pd was 10g/ft 3, the loading of Rh was 8g/ft 3, and the loading of Ru was 2g/ft 3.
Example 3
In step a, the conditions of the specific atmosphere treatment were that the first coating material powder was obtained after treatment at 600 ℃ for 20 hours in an atmosphere containing 10vol.% of water, 20vol.% of oxygen and 70vol.% of nitrogen, and the same as in example 1.
Step B, C, D is the same as in example 1.
Example 4
In step a, the conditions of the specific atmosphere treatment were that the first coating material powder was obtained after treatment at 900 ℃ for 5 hours in an atmosphere containing 10vol.% of water, 20vol.% of oxygen and 70vol.% of nitrogen, and the same as in example 1.
Step B, C, D is the same as in example 1.
Example 5
In step a, the conditions of the specific atmosphere treatment were that the first coating material powder was obtained after treatment at 800 ℃ for 10 hours in an atmosphere containing 1vol.% of water, 15vol.% of oxygen and 84vol.% of nitrogen, otherwise as in example 1.
Step B, C, D is the same as in example 1.
Example 6
In step a, the conditions of the specific atmosphere treatment were that the first coating material powder was obtained after treatment at 800 ℃ for 10 hours in an atmosphere containing 15vol.% of water, 25vol.% of oxygen and 60vol.% of nitrogen, and the same as in example 1.
Step B, C, D is the same as in example 1.
Example 7
Steps a and B are the same as in example 1.
In the step C, when the first coating material slurry is coated on the front section of the carrier at the air inlet end of the cordierite ceramic honeycomb carrier, the length of the front section of the carrier is 50% of the length of the carrier, and the Pt loading amount is 60g/ft 3, otherwise the same as in example 1.
In the step D, when the second coating slurry is coated on the rear section of the gas outlet end carrier of the cordierite ceramic honeycomb carrier, the length of the rear section of the carrier is 50% of the length of the carrier, and the Ru loading amount is 10g/ft 3, otherwise, the same as in example 1.
Example 8
Steps a and B are the same as in example 1.
In the step C, when the first coating material slurry is coated on the front section of the carrier at the air inlet end of the cordierite ceramic honeycomb carrier, the length of the front section of the carrier is 80% of the length of the carrier, and the Pt loading amount is 60g/ft 3, otherwise the same as in example 1.
In the step D, when the second coating slurry is coated on the rear section of the gas outlet end carrier of the cordierite ceramic honeycomb carrier, the length of the rear section of the carrier is 20% of the length of the carrier, and the Ru loading amount is 10g/ft 3, otherwise, the same as in example 1.
Example 9
Steps a and B are the same as in example 1.
In the step C, when the first coating material slurry is coated on the front section of the carrier at the air inlet end of the cordierite ceramic honeycomb carrier, the length of the front section of the carrier is 60% of the length of the carrier, and the Pt loading amount is 60g/ft 3, otherwise the same as in example 1.
In the step D, when the second coating slurry is coated on the rear section of the gas outlet end carrier of the cordierite ceramic honeycomb carrier, the length of the rear section of the carrier is 40% of the length of the carrier, and the Ru loading amount is 10g/ft 3, otherwise, the same as in example 1.
Example 10
Steps a and B are the same as in example 1.
In step C, the Pt loading was 30g/ft 3, otherwise the same as in example 1.
In step D, the Ru loading was 3g/ft 3, otherwise identical to example 1.
Example 11
Steps a and B are the same as in example 1.
In step C, the Pt loading was 70g/ft 3, otherwise the same as in example 1.
In step D, the Ru loading was 20g/ft 3, otherwise identical to example 1.
Example 12
Steps a and B are the same as in example 1.
In step C, the Pt loading was 40g/ft 3, otherwise the same as in example 1.
In step D, the Ru loading was 10g/ft 3, otherwise identical to example 1.
Example 13
Steps a and B are the same as in example 1.
In step C, the Pt loading was 50g/ft 3, otherwise the same as in example 1.
In step D, the Ru loading was 15g/ft 3, otherwise identical to example 1.
Performance testing
1. H 2 -TPR test
The catalysts of example 1 and comparative example 1 were treated with 1H in argon (Ar) at 450℃and then 10 vol% H 2/Ar mixture was introduced after the temperature had fallen to 30℃and the temperature was raised to 600℃at 10℃per minute, and the H 2 signal was detected by a thermal conductivity cell detector, and the test results were shown in FIG. 1.
The results in FIG. 1 show that a new reduction peak, peak 2 in FIG. 1, appears in the H 2 -TPR spectrum of the catalyst of example 1, compared to the catalyst of comparative example 1, indicating that highly active surface oxygen may be formed around Pt, ce after treatment with a specific atmosphere.
2. Catalyst Activity test
The catalysts prepared in comparative examples 1 to 2 and examples 1 to 13 were evaluated for catalyst activity on a simulated atmosphere evaluation system. The evaluation atmosphere was: 1000 ppm CH 4,4600 ppm CO,950 ppm NO,3118 ppm O2,10 vol.% H2 O,10 vol% CO, balanced with N 2, space velocity 50000 h -1. The evaluation results are shown in Table 1 and FIGS. 2 to 4.
Table 1 results of Activity tests for comparative examples 1 to 2 and examples 1 to 13
The light-off temperature is the temperature when the pollutant conversion rate reaches 50%, and the lower the light-off temperature is, the better the catalytic activity of the catalyst is.
As can be seen from fig. 2,3 and table 1, the CH 4 and NO light-off temperatures of the catalyst of example 1 are significantly lower than those of comparative example 1, indicating that treating the Pt coating with a specific atmosphere can form high-activity surface oxygen and more oxygen vacancies around Pt and Ce, significantly improving the CH 4 and NO pollutant purification efficiency of the catalyst. The lower CH 4 and NO light-off temperatures of examples 1 and 2 compared to comparative example 2 indicate better performance of the catalyst with the Pt coating applied to the inner layer or front support and the Ru coating applied to the outer layer or rear support. Comparative example 2 has a similar and higher light-off temperature than the CH 4 and NO of the catalyst of comparative example 3, indicating that the replacement of the more expensive Pd and Rh with the cheaper Pt and Ru, the catalyst also maintains comparable performance to that before replacement.
The results in table 1 and fig. 4 show that the NH 3 emission concentration of example 1 and comparative example 1 is 0 ppm, i.e. no NH 3 is emitted, example 2 is 26 ppm, comparative example 2 is 56 ppm, and comparative example 3 is 66 ppm, indicating that applying the Ru coating to the outer layer or the rear support section allows NH 3 generated on the inner layer or the front support section Pt coating to be decomposed in the Ru coating, significantly reducing the NH 3 emission concentration, and applying the Ru coating to the rear support section is most effective.
Those of ordinary skill in the art will appreciate that: the discussion of any of the embodiments above is merely exemplary and is not intended to suggest that the scope of the invention (including the claims) is limited to these examples; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the invention, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the invention as described above, which are not provided in detail for the sake of brevity.
The present embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, and the like, which are within the spirit and principles of the embodiments of the invention, are intended to be included within the scope of the invention.
Claims (7)
1. The Pt-Ru three-way catalyst is characterized by comprising a honeycomb ceramic carrier, a first coating and a second coating, wherein the first coating and the second coating are coated on a carrier pore canal and are coated on the honeycomb ceramic carrier in a layered or segmented manner;
the first coating is a Pt-containing coating, the first coating comprises Pt and a first catalytic material, and the first catalytic material comprises a first cerium-based material;
The second coating is a Ru-containing coating, the second coating comprises Ru and a second catalytic material, and the second catalytic material comprises one or more of a second cerium-based material and an aluminum-based material;
The loading amount of Pt is 30-70 g/ft 3, and the loading amount of Ru is 3-20 g/ft 3;
the Pt-containing coating is treated for 5-20 hours at 600-900 ℃ in a specific atmosphere, wherein the specific atmosphere comprises 0-15 vol.% of water, 15-25 vol.% of oxygen and 60-85 vol.% of nitrogen;
wherein the layered coating comprises: first, a first coating is coated on the honeycomb ceramic carrier, and then a second coating is coated on the first coating;
The step coating comprises the following steps: and coating a first coating on the front section of the honeycomb ceramic carrier, which is close to the air inlet end, and coating a second coating on the rear section of the honeycomb ceramic carrier, which is close to the air outlet end.
2. The Pt-Ru three-way catalyst according to claim 1, wherein when the sectional coating is adopted, the ratio of the coating length of the first coating layer to the coating length of the second coating layer is 5 to 8: 2-5.
3. The method for preparing a Pt-Ru three-way catalyst according to claim 1 or 2, comprising:
a, preparing a first coating material:
firstly, loading a precursor solution of Pt on a first catalytic material, drying, roasting, and then treating in a specific atmosphere to obtain a first coating material;
B, preparing a second coating material:
firstly, loading a precursor solution of Ru on a second catalytic material, and then drying and roasting to obtain a second coating material;
C forms a first coating:
firstly, ball milling a first coating material, a first binder and water to obtain first coating slurry, then coating the first coating slurry on a honeycomb ceramic carrier, drying, and roasting to form a first coating;
the first coating slurry is coated on the whole section of the honeycomb ceramic carrier or the front section of the carrier close to the air inlet end;
D forming a second coating:
Firstly, ball milling a second coating material, a second binder and water to obtain second coating slurry, then coating the second coating slurry on the first coating or the rear section of the honeycomb ceramic carrier close to the air outlet end, drying and roasting to form a second coating.
4. The method for preparing the Pt-Ru three-way catalyst according to claim 3, wherein:
The mass content of Pt in the first coating material is 0.9-2.5%;
the mass content of Ru in the second coating material is 0.1-0.7%.
5. The method for preparing the Pt-Ru three-way catalyst according to claim 3, wherein:
The solid content of the first coating slurry and the second coating slurry is 30% -40% respectively.
6. The method for preparing the Pt-Ru three-way catalyst according to claim 3, wherein:
The mass ratio of the first coating material to the first binder is 85-97: 3-15;
the mass ratio of the second coating material to the second binder is 85-97: 3-15.
7. The method for preparing the Pt-Ru three-way catalyst according to claim 3, wherein:
the precursor of Pt comprises one or more of nitrate, acetate, hydrochloride or ammonium salt of Pt;
the precursor of Ru comprises one or more of nitrate, acetate, hydrochloride or ammonium salt of Ru;
The first binder and the second binder each independently comprise one or more of aluminum sol, silica sol or zirconium colloid;
The honeycomb ceramic carrier comprises one or more of cordierite, mullite or silicon carbide honeycomb ceramic carriers.
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