CN115254103B - Tail gas purifying catalyst and preparation method thereof - Google Patents

Tail gas purifying catalyst and preparation method thereof Download PDF

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CN115254103B
CN115254103B CN202210896975.1A CN202210896975A CN115254103B CN 115254103 B CN115254103 B CN 115254103B CN 202210896975 A CN202210896975 A CN 202210896975A CN 115254103 B CN115254103 B CN 115254103B
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oxide
gas purifying
purifying catalyst
exhaust gas
catalyst according
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CN115254103A (en
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李秀
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Hubei Hangte Technology Co ltd
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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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • 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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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
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  • Combustion & Propulsion (AREA)
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  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The application provides a tail gas purifying catalyst and a preparation method thereof, belonging to the technical field of motorcycle tail gas treatment. The tail gas purifying catalyst includes active component including Pt-M 1 ‑Al 2 O 3 Oxide, ce-Zr-La-Y oxide, rh-M 2 -Ba oxide and Ce-Zr-La-Nd oxide. The mass ratio of Pt to Rh is 19-39. Wherein M is 1 Selected from one or more of La, ce and Zr, M 2 Any one or more selected from Fe, ce and Co. The application provides the tail gas purifying catalyst with high Pt and low Rh, which not only reduces the consumption of Rh to reduce the cost of noble metal by more than 50 percent, but also can realize high NO under the condition of low Rh x Conversion efficiency. In addition, the degradation proportion of the tail gas purifying catalyst in the service period is low, and the service life of the catalyst is prolonged.

Description

Tail gas purifying catalyst and preparation method thereof
Technical Field
The application relates to the technical field of motorcycle tail gas treatment, in particular to a tail gas purifying catalyst and a preparation method thereof.
Background
The three-way catalyst is used as a means for controlling the emission of the motorcycle to be the most widely applied and the best in effect, and plays an important role in reducing the emission of the motorcycle. With the recent comprehensive upgrade of the emission standards of motor vehicles, the requirements of three noble metals, namely platinum, palladium and rhodium, which play a main role in the three-way catalyst are continuously increased, and the supply of the noble metals is relatively short, so that the price of the noble metals is continuously increased, wherein the price fluctuation of the noble metal Rh is the largest. The greatly increased price of the noble metal directly leads to the great increase of the use cost of the catalyst, and brings great cost pressure to the downstream of the industry, particularly to a host machine factory.
Disclosure of Invention
The application provides an exhaust gas purifying catalyst and a preparation method thereof, which can reduce the cost of the catalyst and prolong the service life of the catalyst.
Embodiments of the present application are implemented as follows:
in a first aspect, the present examples provide an exhaust gas purifying catalyst comprising an active ingredient comprising Pt-M 1 -Al 2 O 3 Oxide, ce-Zr-La-Y oxide, rh-M 2 -Ba oxide and Ce-Zr-La-Nd oxide.
The mass ratio of Pt to Rh is 19-39.
Wherein M is 1 Selected from one or more of La, ce and Zr, M 2 Any one or more selected from Fe, ce and Co.
In the above technical solution, the present application provides a high Pt low Rh exhaust gas purifying catalyst supported on M by Pt 1 -Al 2 O 3 Rh-loaded on M 2 The Ba oxide is matched with the Ce-Zr-La-Y oxide and the Ce-Zr-La-Nd oxide, so that the consumption of Rh is reduced, the cost of noble metal is reduced by more than 50 percent, and high NO under low Rh can be realized x Conversion efficiency. In addition, the degradation proportion of the tail gas purifying catalyst in the service period is low, and the service life of the catalyst is prolonged.
With reference to the first aspect, in a first possible example of the first aspect of the present application, pt-M in the active ingredient 1 -Al 2 O 3 Oxide, ce-Zr-La-Y oxide, rh-M 2 The mass ratio of the Ba oxide to the Ce-Zr-La-Nd oxide is 30-120:30-100:10-50:10-50.
With reference to the first aspect, in a second possible example of the first aspect of the present application, at least one of the following conditions a to d is satisfied:
a. in Pt-M 1 -Al 2 O 3 In the oxide, M 1 The mass fraction of the oxide is 1-20wt%.
b. In the Ce-Zr-La-Y oxide, the mass fraction of the Ce oxide is 10-80 wt%, the mass fraction of the Zr oxide is 10-80 wt%, the mass fraction of the La oxide is 1-10 wt%, and the mass fraction of the Y oxide is 1-10 wt%.
c. In Rh-M 2 M in Ba oxide 2 And Ba is 1-3.
d. In the Ce-Zr-La-Nd oxide, the mass fraction of the Ce oxide is 10-50 wt%, the mass fraction of the Zr oxide is 30-80 wt%, the mass fraction of the La oxide is 1-10 wt%, and the mass fraction of the Nd oxide is 1-6 wt%.
In combination with the first aspect, in a third possible example of the first aspect of the present application, the active ingredient further includes a binder and an auxiliary agent.
Optionally, the binder is pseudo-boehmite.
Optionally, the auxiliary agent is acetate or nitrate of Ce, zr and Ba.
Optionally, the binder calcined oxide and Pt-M 1 -Al 2 O 3 The mass ratio of the oxides is 1-10:30-120.
Optionally, the promoter calcined oxide and Pt-M 1 -Al 2 O 3 The mass ratio of the oxides is 1-10:30-120.
In the above examples, the binder contributes to an improvement in the ability of the active ingredient to adhere to the carrier, and the auxiliary agent contributes to an improvement in the performance of the noble metals Pt and Rh.
In combination with the first aspect, in a fourth possible example of the first aspect of the present application, the exhaust gas purifying catalyst further includes a metal honeycomb carrier, and the active ingredient is supported on the metal honeycomb carrier, wherein the supporting amount of the active ingredient is 100 to 250g/L.
With reference to the first aspect, in a fifth possible example of the first aspect of the present application, the Pt-M 1 -Al 2 O 3 The loading of the oxide is 30-120 g/L, CThe loading of the e-Zr-La-Y oxide is 30-100 g/L, rh-M 2 The loading of the Ba oxide is 10-50 g/L, and the loading of the Ce-Zr-La-Nd oxide is 10-50 g/L.
In a sixth possible example of the first aspect of the present application, in combination with the first aspect, the sum of the loading amounts of Pt and Rh is 5 to 40g/ft 3 。
In a second aspect, the present examples provide a method for producing an exhaust gas purifying catalyst, comprising: the preparation method of the tail gas purifying catalyst comprises the following steps:
mixing the active ingredients with a solvent to prepare active slurry, coating the active slurry on a pretreated metal honeycomb carrier, and sequentially drying and roasting the metal honeycomb carrier loaded with the active slurry to prepare the tail gas purifying catalyst.
Optionally, the pretreatment comprises the steps of after purging the metal honeycomb carrier by a high-pressure air gun carrier, preserving the heat of the metal honeycomb carrier in an oxygen-containing atmosphere at 500-950 ℃ for 1-5 h.
Optionally, the drying includes hot air blowing at 60-120 ℃ to a water loss rate of > 90%.
Optionally, the roasting comprises heat preservation at 500-600 ℃ for 2-3 hours.
In the technical scheme, the preparation method of the tail gas purifying catalyst is simple and convenient, and the prepared tail gas purifying catalyst has stable structure, so that the cost of noble metal is reduced by more than 50%, and high NO under low Rh can be realized x Conversion efficiency.
With reference to the second aspect, in a first possible example of the second aspect of the present application, the above Pt-M 1 -Al 2 O 3 The oxide is prepared by the following method:
platinum nitrate solution and M 1 -Al 2 O 3 Mixing the powder to make the platinum nitrate solution be immersed in M in equal volume 1 -Al 2 O 3 Drying the powder to obtain Pt-M 1 -Al 2 O 3 An oxide.
With reference to the second aspect, in a second possible example of the second aspect of the present application, the above-mentioned Rh-M 2 -Ba oxidationThe product is prepared by the following steps:
at 60-90 ℃, M is contained 2 Ion and Ba 2+ Mixing the salt solution of (2) with rhodium nitrate solution to obtain a first mixed solution, adding citric acid into the first mixed solution, maintaining the temperature and stirring for 1-3 h to obtain a second mixed solution, and sequentially drying and roasting the second mixed solution to obtain Rh-M 2 -Ba oxide.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a graph showing comparison of light-off test data of the exhaust gas purifying catalysts prepared in examples 1 to 2 and comparative example 1 of the present application.
Detailed Description
Embodiments of the present application will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustration of the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Pt has the lowest price among three noble metals of platinum, palladium and rhodium, rh has the highest price, and Rh has NO to NO x The catalytic activity of the conversion is best. If a high Pt low Rh catalyst is developed based on motorcycle emission regulations, and NO of the low Rh catalyst is ensured x The conversion performance meets the requirement, so that the cost of noble metal of the three-way catalyst can be effectively reduced.
The following specifically describes an exhaust gas purifying catalyst and a preparation method thereof according to an embodiment of the present application:
the application provides a tail gas purifying catalyst, its packageComprises active ingredients including Pt-M 1 -Al 2 O 3 Oxide, ce-Zr-La-Y oxide, rh-M 2 -Ba oxide and Ce-Zr-La-Nd oxide.
And the mass ratio of Pt to Rh is 19-39, belonging to the noble metal configuration with high Pt and low Rh.
Pt-M in active ingredient 1 -Al 2 O 3 Oxide, ce-Zr-La-Y oxide, rh-M 2 The mass ratio of the Ba oxide to the Ce-Zr-La-Nd oxide is 30-120:30-100:10-50:10-50.
As an example, the ratio of the mass ratio of Pt to Rh may be 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, or 39.
In Pt-M 1 -Al 2 O 3 In the oxide, M 1 The mass fraction of the oxide is 1 to 20 weight percent, M 1 Selected from any one or more of La, ce and Zr.
By way of example, M 1 The mass fraction of the oxide may be 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt% or 20wt%.
By way of example, M 1 The catalyst may be selected from La, ce or Zr alone, la, ce complex, la, zr complex, ce, zr complex, la, ce, zr complex.
In the Ce-Zr-La-Y oxide, the mass fraction of the Ce oxide is 10-80 wt%, the mass fraction of the Zr oxide is 10-80 wt%, the mass fraction of the La oxide is 1-10 wt%, and the mass fraction of the Y oxide is 1-10 wt%.
As an example, the mass fraction of Ce oxide may be 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, or 80wt%, the mass fraction of Zr oxide may be 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, or 80wt%, the mass fraction of La oxide may be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%, and the mass fraction of Y oxide may be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%.
In Rh-M 2 M in Ba oxide 2 And Ba is 1-3, M 2 Any one or more selected from Fe, ce and Co.
By way of example, M 2 The ratio of the molar ratio to Ba may be 1, 1.5, 2, 2.5 or 3.
By way of example, M 2 Can be selected from Fe, ce or Co alone, or Fe, ce complex, or Fe, co complex, or Ce, co complex, or Fe, ce, co complex.
In the Ce-Zr-La-Nd oxide, the mass fraction of the Ce oxide is 10-50 wt%, the mass fraction of the Zr oxide is 30-80 wt%, the mass fraction of the La oxide is 1-10 wt%, and the mass fraction of the Nd oxide is 1-6 wt%.
As an example, the mass fraction of Ce oxide may be 10wt%, 20wt%, 30wt%, 40wt%, or 50wt%, the mass fraction of Z oxide r may be 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, and 80wt%, the mass fraction of La oxide may be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%, and the mass fraction of Nd oxide may be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, or 6wt%.
The active ingredient also comprises an adhesive and an auxiliary agent.
The adhesive is favorable for improving the capability of the active ingredients to be attached to the carrier, and the auxiliary agent is favorable for improving the performance of noble metals Pt and Rh.
Optionally, the binder is pseudo-boehmite.
The chemical formula of the pseudo-boehmite is AlOOH.nH 2 O，n＝0.08～0.62。
Optionally, the binder calcined oxide and Pt-M 1 -Al 2 O 3 The mass ratio of the oxides is 1-10:30-120.
Optionally, the auxiliary agent is acetate or nitrate of Ce, zr and Ba.
Optionally, the auxiliary agent comprises cerium acetate, zirconium acetate and barium acetate.
Optionally, the promoter calcined oxide and Pt-M 1 -Al 2 O 3 The mass ratio of the oxides is 1-10:30-120.
The tail gas purifying catalyst also comprises a metal honeycomb carrier, wherein the active ingredients are loaded on the metal honeycomb carrier, and the loading amount of the active ingredients is 100-250 g/L.
As examples, the loading of the active ingredient may be 100g/L, 120g/L, 150g/L, 180g/L, 200g/L, 230g/L or 250g/L.
Pt-M 1 -Al 2 O 3 The loading of the oxide is 30-120 g/L.
By way of example, pt-M 1 -Al 2 O 3 The loading of the oxide may be 30g/L, 40g/L, 50g/L, 60g/L, 70g/L, 80g/L, 90g/L, 100g/L, 110g/L or 120g/L.
The loading of Ce-Zr-La-Y oxide is 30-100 g/L.
As examples, the loading of Ce-Zr-La-Y oxide may be 30g/L, 40g/L, 50g/L, 60g/L, 70g/L, 80g/L, 90g/L or 100g/L.
The loading of Ce-Zr-La-Y oxide is 30-100 g/L.
As examples, the loading of Ce-Zr-La-Y oxide may be 30g/L, 40g/L, 50g/L, 60g/L, 70g/L, 80g/L, 90g/L or 100g/L.
Rh-M 2 The loading of the Ba oxide is 10-50 g/L.
Rh-M as an example 2 The loading of the Ba oxide may be 10g/L, 20g/L, 30g/L, 40g/L or 50g/L.
The loading amount of the Ce-Zr-La-Nd oxide is 10-50 g/L.
As examples, the loading of Ce-Zr-La-Nd oxide may be 10g/L, 20g/L, 30g/L, 40g/L or 50g/L.
The sum of the loading of Pt and Rh is 5-40 g/ft 3 。
As an example, the sum of Pt and Rh loading amounts is 5g/ft 3 、10g/ft 3 、15g/ft 3 、20g/ft 3 、25g/ft 3 、30g/ft 3 、35g/ft 3 Or 40g/ft 3 。
The application provides a high Pt low RhExhaust gas purifying catalyst supported on M by Pt 1 -Al 2 O 3 Rh-loaded on M 2 The Ba oxide is matched with the Ce-Zr-La-Y oxide and the Ce-Zr-La-Nd oxide, so that the consumption of Rh is reduced, the cost of noble metal is reduced by more than 50 percent, and high NO under low Rh can be realized x Conversion efficiency. In addition, the degradation proportion of the tail gas purifying catalyst in the service period is low, and the service life of the catalyst is prolonged.
The application also provides a preparation method of the tail gas purifying catalyst, which comprises the following steps:
s1, preparing active slurry
Pt-M is mixed according to the proportion 1 -Al 2 O 3 Oxide powder, ce-Zr-La-Y oxide powder, rh-M 2 -Ba oxide powder, ce-Zr-La-Nd oxide powder, adhesive, auxiliary agent and solvent are mixed to prepare active slurry.
The solid content of the active slurry is 30-50%, the pH value is 3-5, the viscosity is 100 mPa.s-5 Pa.s, and the granularity D50 is 6-8 mu m.
Alternatively, the solvent includes pure water and glacial acetic acid.
Wherein Pt-M 1 -Al 2 O 3 The oxide powder is prepared by the following method:
platinum nitrate solution and M 1 -Al 2 O 3 Mixing the powder to make the platinum nitrate solution be immersed in M in equal volume 1 -Al 2 O 3 Drying the powder to obtain Pt-M 1 -Al 2 O 3 Oxide powder.
Alternatively, the method of impregnation includes an equal volume impregnation into M after atomizing the platinum nitrate solution 1 -Al 2 O 3 Powder is prepared.
Alternatively, the volume of the platinum nitrate solution diluted with pure water and M 1 -Al 2 O 3 The ratio of the pore volume of the powder is 0.95-1.05.
Optionally, the drying comprises drying at 80-120 ℃ for 1-4 hours.
Rh-M 2 The Ba oxide powder is prepared by the following methodObtaining:
at 60-90 ℃, M is contained 2 Ion and Ba 2+ Mixing the salt solution of (2) with rhodium nitrate solution to obtain a first mixed solution, adding citric acid into the first mixed solution, maintaining the temperature and stirring for 1-3 h to obtain a second mixed solution, and sequentially drying and roasting the second mixed solution to obtain Rh-M 2 -Ba oxide powder.
Alternatively, M in salt solution 2 Ion and Ba 2+ The concentration of (C) is 0.3-1 mol/L respectively.
Alternatively, the ratio of the molar ratio of citric acid to metal cations is 1-3, the cations including M 2 Ion and Ba 2+ 。
Optionally, the second mixed liquor is in the shape of rice soup.
Optionally, the drying comprises drying at 80-120 ℃ for 10-30 hours.
Optionally, the roasting comprises heating to 500-600 ℃ within 1.5-2.5 h, preserving heat for 2-3 h at 500-600 ℃, and then cooling to room temperature.
S2, coating application
According to the coating amount of 100-250 g/L, the prepared active slurry is coated on a pretreated metal honeycomb carrier and dried until the water loss rate is more than 90%.
Optionally, the drying includes hot air purging at 60-120 ℃.
Optionally, the pretreatment comprises the steps of after purging the metal honeycomb carrier by a high-pressure air gun carrier, preserving the heat of the metal honeycomb carrier in an oxygen-containing atmosphere at 500-950 ℃ for 1-5 h.
The high-pressure air gun carrier is purged to remove dust of the metal honeycomb carrier, and the metal honeycomb carrier is kept at the temperature of 500-950 ℃ for 1-5 h in an oxygen-containing atmosphere to form a metal oxide film on the surface of the metal honeycomb carrier.
S3, roasting the catalyst
Heating to 500-600 ℃ within 1.5-2.5 h, preserving heat for 2-3 h at 500-600 ℃, and cooling to room temperature to obtain the tail gas purifying catalyst.
The preparation method of the tail gas purifying catalyst is simple and convenient, and the prepared tail gas purifying catalyst is combinedStable structure, 50% lower noble metal cost and high NO at low Rh x Conversion efficiency.
An exhaust gas purifying catalyst and a method for preparing the same of the present application are described in further detail below with reference to examples.
Example 1
The application provides an exhaust gas purifying catalyst and a preparation method thereof, wherein the method comprises the following steps:
s1, preparing Pt-La-Al 2 O 3 Oxide powder
Uniformly mixing 1.428g of a first platinum nitrate solution with 80g of pure water to prepare a second platinum nitrate solution, wherein the mass concentration of the first platinum nitrate solution is 14.1wt%, and atomizing the second platinum nitrate solution to dip 56.54g of La-Al in an equal volume manner 2 O 3 Stirring the mixture in the powder uniformly to obtain a mixture, namely La-Al 2 O 3 The mass ratio of La oxide is 4wt%, and the mixture is dried for 3 hours in an oven at 120 ℃ to prepare Pt-La-Al 2 O 3 Oxide powder.
S2, preparing Rh-Ce-Ba oxide powder
15.6g of cerium acetate and 12.56g of barium acetate are dissolved in 200g of pure water, heated and stirred in a water bath at 90 ℃, then 0.101g of rhodium nitrate solution is added to prepare a first mixed solution, the mass concentration of the rhodium nitrate solution is 10.5wt%, 14.17g of citric acid is added to the first mixed solution, the water bath at 90 ℃ is continued to be heated and stirred for 2 hours, a rice-soup-shaped second mixed solution is prepared, the second mixed solution is placed in an oven to be dried for 15 hours at 120 ℃, then the second mixed solution is transferred into a resistance furnace to be roasted, the roasting procedure is that 2.5 hours is heated to 550 ℃, the temperature is kept for 2.5 hours at 550 ℃, and then the mixed solution is cooled to room temperature along with the furnace, so as to prepare Rh-Ce-Ba oxide powder.
S3, preparing active slurry
54.2g of Pt-La-Al 2 O 3 Oxide, 55.10g Ce-Zr-La-Y oxide, 16.01gRh-Ce-Ba oxide, 24.0g Ce-Zr-La-Nd oxide, 4.89g pseudo-boehmite, 7.48g cerium acetate, 4.21g zirconium acetate and 6.14g barium acetate are added into a ball milling tank, 178.0g pure water and 6.0g glacial acetic acid are added to prepare active slurry, the solid content of the active slurry is 45%,the pH value is 4.1, the viscosity is 0.626Pa.s, and then the mixture is ball-milled until the granularity D50 of the active slurry is 6-8 mu m.
S4, coating application
The prepared active slurry is coated on a pretreated metal honeycomb carrier according to the coating amount of 160.212g/L, and is dried at 70 ℃ until the water loss rate is more than 90%. The pretreatment comprises the steps of purging the metal honeycomb carrier by a high-pressure air gun carrier, and then preserving the heat of the metal honeycomb carrier in an oxygen-containing atmosphere at 600 ℃ for 2 hours.
S5, roasting the catalyst
And (3) placing the dried metal honeycomb carrier loaded with the active slurry into a resistance furnace for roasting, wherein the roasting program is 2.5h, heating to 550 ℃, preserving heat for 2.5h at 550 ℃, and then cooling to room temperature along with the furnace. The catalyst is prepared, the mass ratio of Pt to Rh in the catalyst is 19:1, and the total loading of Pt and Rh is 6g/ft 3 。
Example 2
The application provides an exhaust gas purifying catalyst and a preparation method thereof, wherein the method comprises the following steps:
s1, preparing Pt-La-Al 2 O 3 Oxide powder
Uniformly mixing 1.466g of a first platinum nitrate solution with 80g of pure water to prepare a second platinum nitrate solution, wherein the mass concentration of the first platinum nitrate solution is 14.1wt%, and atomizing the second platinum nitrate solution to dip 56.54g of La-Al in an equal volume manner 2 O 3 Stirring the mixture in the powder uniformly to obtain a mixture, namely La-Al 2 O 3 The mass ratio of La oxide is 4wt%, and the mixture is dried for 3 hours in an oven at 120 ℃ to prepare Pt-La-Al 2 O 3 Oxide powder.
S2, preparing Rh-Ce-Ba oxide powder
15.6g of cerium acetate and 12.56g of barium acetate are dissolved in 200g of pure water, heated and stirred in a water bath at 90 ℃, then 0.051g of rhodium nitrate solution is added to prepare a first mixed solution, the mass concentration of the rhodium nitrate solution is 10.5wt%, 14.17g of citric acid is added to the first mixed solution, the water bath at 90 ℃ is continued to be heated and stirred for 2 hours, a rice-soup-shaped second mixed solution is prepared, the second mixed solution is placed in an oven to be dried for 15 hours at 120 ℃, then the second mixed solution is transferred into a resistance furnace to be roasted, the roasting procedure is that 2.5 hours is heated to 550 ℃, the temperature is kept for 2.5 hours at 550 ℃, and then the mixture is cooled to room temperature along with a furnace, so as to prepare Rh-Ce-Ba oxide powder.
S3, preparing active slurry
54.21g of Pt-La-Al 2 O 3 Oxide, 55.10g Ce-Zr-La-Y oxide, 16.01gRh-Ce-Ba oxide, 24.0g Ce-Zr-La-Nd oxide, 4.89g pseudo-boehmite, 7.48g cerium acetate, 4.21g zirconium acetate and 6.14g barium acetate are added into a ball milling tank, 178.0g pure water and 6.0g glacial acetic acid are added to prepare active slurry, the solid content of the active slurry is 45%, the pH value is 3.7, the viscosity is 0.813Pa.s, and then the active slurry is ball milled until the granularity D50 of the active slurry is 6-8 mu m.
S4, coating application
The prepared active slurry is coated on a pretreated metal honeycomb carrier according to the coating amount of 160.212g/L, and is dried at 70 ℃ until the water loss rate is more than 90%. The pretreatment comprises the steps of purging the metal honeycomb carrier by a high-pressure air gun carrier, and then preserving the heat of the metal honeycomb carrier in an oxygen-containing atmosphere at 600 ℃ for 2 hours.
S5, roasting the catalyst
And (3) placing the dried metal honeycomb carrier loaded with the active slurry into a resistance furnace for roasting, wherein the roasting program is 2.5h, heating to 550 ℃, preserving heat for 2.5h at 550 ℃, and then cooling to room temperature along with the furnace. The catalyst is prepared, the mass ratio of Pt to Rh in the catalyst is 39:1, and the total loading of Pt and Rh is 6g/ft 3 。
Comparative example 1
The application provides an exhaust gas purifying catalyst and a preparation method thereof, wherein the method comprises the following steps:
s1, preparing precursor slurry
56.54g of La-Al 2 O 3 The oxide, 55.10g Ce-Zr-La-Y oxide, 4.89g pseudo-boehmite, 7.48g cerium acetate, 4.21g zirconium acetate and 6.14g barium acetate are added into a ball milling tank, 145.36g pure water and 6.0g glacial acetic acid are added to prepare precursor slurry, la-Al 2 O 3 The La oxide content was 4wt%, the solid content of the precursor slurry was 42%, the pH was 4.5, and the viscosity was 0.592Pa.sAnd ball milling until the granularity D50 of the precursor slurry is 6-8 mu m.
S2, preparing active slurry
200g of the prepared precursor slurry, 0.847g of a platinum nitrate solution and 0.228g of a rhodium nitrate solution were mixed to prepare a third mixed solution, 1.78g of pure water was added to the third mixed solution, and the mixture was stirred for 1 hour and allowed to stand for 1 hour to prepare an active slurry having a solid content of 40%.
S3, coating application
The prepared active slurry is coated on a pretreated metal honeycomb carrier according to the coating amount of 120g/L, and is dried at 70 ℃ until the water loss rate is more than 90%. The pretreatment comprises the steps of purging the metal honeycomb carrier by a high-pressure air gun carrier, and then preserving the heat of the metal honeycomb carrier in an oxygen-containing atmosphere at 600 ℃ for 2 hours.
S4, roasting the catalyst
And (3) placing the dried metal honeycomb carrier loaded with the active slurry into a resistance furnace for roasting, wherein the roasting procedure is that the temperature is raised to 550 ℃ for 2 hours, the temperature is kept at 550 ℃ for 2.5 hours, and then the metal honeycomb carrier is cooled to room temperature along with the furnace. The catalyst is prepared, the mass ratio of Pt to Rh in the catalyst is 5:1, and the total loading of Pt and Rh is 6g/ft 3 。
Test example 1
The activity evaluation of the catalyst was carried out on a catalyst sample evaluation tester (Tianjin Li Yuan, science and technology Co., ltd.) using a monolithic catalyst having a diameter of 20X 30X 300cpsi, pre-treating at 500℃for 1 hour in a reaction gas atmosphere, and then introducing N 2 Purging and cooling to room temperature, and performing ignition characteristic test, wherein the temperature is required to be increased from room temperature to 500 ℃ at a heating rate of 20 ℃/min, and the airspeed is 55000h -1 And (3) measuring under the condition. The reaction gas is simulated gas distribution of automobile exhaust, and the composition of the reaction gas is 0.60 percent of CO and 0.15 percent of THC (C 3 H 8 :C 3 H 6 ＝1：2)，0.08％NO x ，0.6％O 2 ，10％CO 2 Balance gas N 2 . The contents of each component in the exhaust gas before and after the reaction were analyzed by using an HORIBA7400H type automobile exhaust gas analyzer (HORIBA Co., japan), the conversion rates of each component were calculated, and the results are shown in FIG. 1 and Table 1, FIG. 1 being a pair of light-off test data of the exhaust gas purifying catalysts prepared in examples 1 to 2 and comparative example 1Table 1 is a comparison of the light-off test data indexes of the exhaust gas purifying catalysts prepared in examples 1 to 2 and comparative example 1.
Table 1 comparison of the light-off test data indexes of the exhaust gas purifying catalysts prepared in examples 1 to 2 and comparative example 1
As can be seen from table 1 and fig. 1, the light-off performance of example 1 and example 2 is significantly improved, and the light-off performance of example 1 is better than that of comparative example 1.
In terms of noble metal cost, calculated according to average price of 2021 in quarter, tax-containing prices are respectively Pt:252 yuan/g, rh:5639 yuan/g, example 1 was reduced by 55% and example 2 was reduced by 66%.
The exhaust gas purifying catalysts prepared in examples 1-2 and comparative example 1 were subjected to the whole vehicle emission performance verification, and the whole vehicle emission performance calibration was carried out in 125cc state four-vehicle, including the whole vehicle emission after the durability of the fresh state and 2 ten thousand kilometers of real vehicles, and the results are shown in table 2, and table 2 shows the comparison of the test results of the exhaust gas purifying catalysts prepared in examples 1-2 and comparative example 1 applied to 125cc state four-motorcycle type I tests.
Table 2 comparison of test results of type I test of a certain 125cc national four-motorcycle with exhaust gas purifying catalysts prepared in examples 1 to 2 and comparative example 1
As can be seen from Table 2, from the results of the type I test emission of the whole car, the catalysts prepared in examples 1 to 2 and comparative example 1 can meet the national four emission requirements of motorcycles, but after 20000km, NO in comparative example 1 x To 97%, whereas the NO of examples 1-2 x Only 65% and 71%, which means that the exhaust gas purifying catalysts prepared in examples 1 to 2 have a lower degradation ratio in the service cycle and a longer service life.
The foregoing is merely a specific embodiment of the present application and is not intended to limit the present application, and various modifications and variations may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (16)

1. An exhaust gas purifying catalyst, characterized in that the exhaust gas purifying catalyst comprises an active ingredient, pt-M in the active ingredient 1 -Al 2 O 3 Oxide, ce-Zr-La-Y oxide, rh-M 2 The mass ratio of the Ba oxide to the Ce-Zr-La-Nd oxide is 30-120:30-100:10-50:10-50;
the mass ratio of Pt to Rh is 19-39;
wherein M is 1 Selected from one or more of La, ce and Zr, M 2 Any one or more selected from Fe, ce and Co.
2. The exhaust gas purifying catalyst according to claim 1, characterized in that at least one of the following conditions a to d is satisfied:
a. at the Pt-M 1 -Al 2 O 3 In the oxide, M 1 The mass fraction of the oxide is 1-20wt%;
b. in the Ce-Zr-La-Y oxide, the mass fraction of the Ce oxide is 10-80 wt%, the mass fraction of the Zr oxide is 10-80 wt%, the mass fraction of the La oxide is 1-10 wt%, and the mass fraction of the Y oxide is 1-10 wt%;
c. at the Rh-M 2 M in Ba oxide 2 And Ba is 1-3;
d. in the Ce-Zr-La-Nd oxide, the mass fraction of Ce oxide is 10-50 wt%, the mass fraction of Zr oxide is 30-80 wt%, the mass fraction of La oxide is 1-10 wt%, and the mass fraction of Nd oxide is 1-6 wt%.
3. The exhaust gas purifying catalyst according to claim 1 or 2, characterized in that the active ingredient further comprises a binder and an auxiliary agent.
4. The exhaust gas purifying catalyst according to claim 3, wherein the binder is pseudo-boehmite.
5. The exhaust gas purifying catalyst according to claim 3, wherein the auxiliary is acetate or nitrate of Ce, zr, ba.
6. The exhaust gas purifying catalyst according to claim 3, wherein the adhesive agent is calcined oxide and Pt-M 1 -Al 2 O 3 The mass ratio of the oxides is 1-10:30-120.
7. The exhaust gas purifying catalyst according to claim 3, wherein the promoter is calcined oxide and Pt-M 1 -Al 2 O 3 The mass ratio of the oxides is 1-10:30-120.
8. The exhaust gas purifying catalyst according to claim 1 or 2, characterized in that the exhaust gas purifying catalyst further comprises a metal honeycomb carrier on which the active ingredient is supported, the supporting amount of the active ingredient being 100 to 250g/L.
9. The exhaust gas purifying catalyst according to claim 8, characterized in that the Pt-M 1 -Al 2 O 3 The loading capacity of the oxide is 30-120 g/L, the loading capacity of the Ce-Zr-La-Y oxide is 30-100 g/L, and the Rh-M 2 The loading amount of the Ba oxide is 10-50 g/L, and the loading amount of the Ce-Zr-La-Nd oxide is 10-50 g/L.
10. The exhaust gas purifying catalyst according to claim 8, wherein a sum of loading amounts of Pt and Rh is 5 to 40g/ft 3 。
11. A method for producing an exhaust gas purifying catalyst according to any one of claims 1 to 10, characterized in that the method for producing an exhaust gas purifying catalyst comprises:
mixing the active ingredients with a solvent to prepare active slurry, coating the active slurry on a pretreated metal honeycomb carrier, and sequentially drying and roasting the metal honeycomb carrier loaded with the active slurry to prepare the tail gas purifying catalyst.
12. The method for preparing an exhaust gas purifying catalyst according to claim 11, wherein the pretreatment comprises keeping the metal honeycomb carrier in an oxygen-containing atmosphere at 500 to 950 ℃ for 1 to 5 hours after purging the metal honeycomb carrier with a high-pressure air gun carrier.
13. The method for producing an exhaust gas purifying catalyst according to claim 11, wherein said drying includes blowing hot air at 60 to 120 ℃ to a water loss rate of > 90%.
14. The method for producing an exhaust gas purifying catalyst according to claim 11, wherein said calcination includes heat preservation at 500 to 600 ℃ for 2 to 3 hours.
15. The method for producing an exhaust gas purifying catalyst according to claim 11, wherein the Pt-M 1 -Al 2 O 3 The oxide is prepared by the following method:
platinum nitrate solution and M 1 -Al 2 O 3 Mixing the powder to make the platinum nitrate solution be immersed in M in equal volume 1 -Al 2 O 3 Drying the powder to obtain Pt-M 1 -Al 2 O 3 An oxide.
16. The method for producing an exhaust gas purifying catalyst according to claim 11, wherein the Rh-M 2 -Ba oxide is prepared by the following method:
at 60-90 ℃, M is contained 2 Ion and Ba 2+ Mixing the salt solution of (2) with rhodium nitrate solution to obtain a first mixed solution, adding citric acid into the first mixed solution, maintaining the temperature and stirring for 1-3 h to obtain a second mixed solution, and sequentially drying and roasting the second mixed solution to obtain Rh-M 2 -Ba oxide.
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