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CN115518675B - Has low temperature NO x SCR catalyst with adsorption function and application thereof - Google Patents

Has low temperature NO x SCR catalyst with adsorption function and application thereof Download PDF

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Publication number
CN115518675B
CN115518675B CN202211111496.0A CN202211111496A CN115518675B CN 115518675 B CN115518675 B CN 115518675B CN 202211111496 A CN202211111496 A CN 202211111496A CN 115518675 B CN115518675 B CN 115518675B
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coating
catalyst
substrate
zone
partition
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CN115518675A (en
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汪秀秀
庞磊
冯坦
董才月
赵俊平
赵月
陈镇
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Dongfeng Trucks Co ltd
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Dongfeng Trucks 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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/72—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing iron group metals, noble metals or copper
    • B01J29/74—Noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
    • 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
    • B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B01J23/745—Iron
    • 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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/72—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing iron group metals, noble metals or copper
    • B01J29/76—Iron group metals or copper
    • 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
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • 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
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
    • B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
    • 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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  • Oil, Petroleum & Natural Gas (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Catalysts (AREA)

Abstract

The application discloses a low-temperature NO-bearing device X The SCR catalyst with the adsorption function and the application thereof are characterized in that a flow-through type monolithic substrate is adopted as a catalyst product, a partition coating catalyst is arranged on the substrate, the partition coating catalyst comprises a first partition coating, a second partition coating and a third partition coating, the first partition coating is clung to the wall of the substrate and is positioned at the air inlet end of the substrate, the second partition coating is clung to the wall of the substrate and is positioned at the air outlet end of the substrate, the sum of the lengths of the first partition coating and the second partition coating is equal to the total length of the substrate, and the third partition coating is positioned on the second partition coating and has the same length as the second partition coating; the first zone coating comprises a passive nitrogen oxide adsorption catalyst composition and the second zone coating comprises NO 2 Reduction catalyst composition, third zone coating comprising NO X Reducing the catalyst composition; the first zone coating absorbs NO in the tail gas at a temperature below 150 DEG C X And releasing NO above 250 DEG C X The method comprises the steps of carrying out a first treatment on the surface of the The second zone coating layer will NO X NO of a certain proportion of 2 Convert to NO, make NO 2 And the concentration ratio of NO is 0.8-1.2: 1, a step of; the third zone coating layer will NO X Conversion to N 2 。

Description

Has low temperature NO X SCR catalyst with adsorption function and application thereof
Technical Field
The application belongs to the field of catalysts for post-treatment of tail gas of fuel vehicles, and particularly relates to a catalyst with low-temperature NO X An SCR catalyst with adsorption function and application thereof.
Background
Negative weather effect based on oxynitrideImpact, the U.S. Environmental Protection Agency (EPA) prescribes the reduction of nitrogen dioxide (NO) 2 ) Nitric Oxide (NO) and nitrous oxide (N) 2 O) is collectively referred to as NO X . The tail gas of diesel vehicle with high air-fuel ratio is NO X The main source of emissions. As a typical lean-burn engine, diesel vehicles generally employ a combination of selective reduction catalytic SCR technology and cooled exhaust gas recirculation technology to meet stringent emissions regulations. However, the SCR catalyst can only exert good NO if the exhaust gas temperature reaches the ignition temperature (more than 200 ℃) X And the emission reduction effect is achieved. The tail gas temperature during cold start of diesel vehicle is below 180deg.C and lasts for about 3min, during which NO X The emissions are discharged into the air with little treatment. NO of cold start emission X Contributing to total NO X 80% of the emissions. In addition, in order to improve the fuel economy, technologies such as advanced combustion, engine miniaturization, turbocharging and the like are continuously updated and applied to diesel engines, so that the exhaust temperature is low, and the duration and the strength of the cold start effect are more remarkable.
To solve NO in tail gas of cold start stage X Emission problem, passive NO X Adsorbents (PNAs) have been developed to adsorb NO at low SCR activity X With the increase of the temperature of the tail gas, the SCR to be downstream can catalyze with high efficiency, and the PNA can convert NO X Rapidly release and recover NO X Adsorption function.
Kangmins proposes a PNA-carrying architecture, namely DOC+PNA+SCRF (i.e. SCR catalyst coated on a particle trap (DPF) +CC-SCR. The system has excellent NO X The emission reduction effect, but involves 5 post-processing units outside the machine, the system architecture is complex, the implementation cost is high, and great pressure is brought to packaging and arrangement. Zhuang Xinmo discloses a DOC and PNA coupling scheme called DCSC unit, and performs various patent layouts aiming at different framework structure molecular sieve components of DCSC. The disadvantage of this unit is that since DCSC contains a large amount of noble metal active components, which are unevenly distributed in the carrier multi-stage pore canal, agglomeration easily occurs at high temperature to form large particles, and these agglomerated particles have a large charge density, which easily gives out electrons, to NO in the original emission X Oxidation is far greater than adsorptionWith passive NO, resulting in DCSC expression X Low adsorption capacity and NO due to DCSC treatment 2 Far higher than NO, unfavorable for subsequent NH 3 SCR rapid reaction, reducing the rate of selective catalytic reduction treatment.
Disclosure of Invention
To solve NO in tail gas in cold start stage in the prior art X The application provides the following technical scheme:
in a first aspect, the present application provides a method for producing a low temperature NO X The adsorption function SCR catalyst adopts a flow-through monolithic substrate, a partition coating catalyst is arranged on the substrate, the partition coating catalyst comprises a first partition coating, a second partition coating and a third partition coating, wherein the first partition coating is clung to the wall of the substrate and is positioned at the air inlet end of the substrate, the second partition coating is clung to the wall of the substrate and is positioned at the air outlet end of the substrate, the sum of the lengths of the first partition coating and the second partition coating is equal to the total length of the substrate, and the third partition coating is positioned on the second partition coating and has the same length as the second partition coating; the first zone coating comprises a passive nitrogen oxide adsorption catalyst composition and the second zone coating comprises NO 2 Reduction catalyst composition, third zone coating comprising NO X Reducing the catalyst composition; the first zone coating absorbs NO in the tail gas at a temperature below 150 DEG C X And releasing NO above 250 DEG C X The method comprises the steps of carrying out a first treatment on the surface of the The second zone coating layer will NO X NO of a certain proportion of 2 Convert to NO, make NO 2 And the concentration ratio of NO is 0.8-1.2: 1, a step of; the third zone coating layer will NO X Conversion to N 2 。
In some embodiments provided by the present application, the sum of the third zone coating and the second zone coating thickness is equal to the first zone coating thickness.
In some embodiments provided herein, the length of the second zone coating and the third zone coating is 30% to 70%, preferably 70%, of the total length of the substrate.
In some embodiments provided herein, a passive oxynitride adsorption catalyst composition, NO 2 Reduction catalyst composition, NO X The loading ratio of the reduction catalyst composition is 30-50:10：95～120。
in some embodiments provided herein, the passive nox adsorber catalyst composition in the first zone coating has an loading of from 30 to 50g/L; NO in the second zone coating 2 The loading of the reduction catalyst composition was 10.+ -.2 g/L; NO in the third zone coating X The loading of the reduction catalyst composition is 95-120 g/L.
In some embodiments of the present application, the substrate is one of cordierite, silicon carbide, and a metal material.
In some embodiments of the present application, the metal material is one of Fe-Cr-Ni alloy, co-Cr-Ni alloy, and Ni-Cr-Mo alloy.
In some embodiments provided herein, a passive oxynitride adsorption catalyst composition includes a precious metal active ingredient that is at least one of Pd, ag, co, and a first adsorptive refractory carrier that is a first molecular sieve or metal oxide.
In some embodiments provided herein, the passive oxynitride adsorption catalyst composition further comprises a base metal or a rare earth metal, at least one of the base metals being Mn, co, zr, ni, the rare earth metal being Ce or La.
In some embodiments of the application provided, NO 2 The reduction catalyst composition comprises NO 2 Reducing the active ingredient and a second adsorptive refractory carrier, NO 2 The reduction active component is one or more of ferric oxide, cobalt oxide, copper oxide, barium oxide, calcium oxide, magnesium oxide, strontium oxide, tin oxide and germanium oxide, and the second adsorptive refractory carrier is silicon oxide or gamma-alumina.
In some embodiments of the application provided, NO X The reduction catalyst composition comprises NO X Reducing the active ingredient and a third adsorptive refractory carrier, NO X The reducing active ingredient is one or more of Cu, mn, V, fe, co, W, ni, zn, ti, cr, Y, zr, nb, mo, and the third adsorptive refractory carrier comprises one or more of analcite, chabazite, heulandite, stilbite, erionite, mordenite, calcium zeolite, and sodium zeoliteOr a symbiotic mixture.
In a second aspect, the present application provides a method comprising providing a low temperature NO X A lean burn engine tail gas treatment device of an SCR catalyst with an adsorption function.
Compared with the prior art, the application uses PNA catalyst and NO 2 The reduction catalyst and the SCR catalyst are supported on the same substrate, and the PNA catalyst solves the problem of low-temperature cold start NO X Emissions problems, NO 2 The reduction catalyst improves oxidation side reaction of PNA catalyst, on one hand, ensures NO and NO in tail gas 2 The equilibrium of (2) is close to 1:1, promoting a rapid SCR reaction, on the other hand, avoiding low temperature NO X The adsorption reaction generates excessive NO 2 From the source control N 2 O is generated and reacted.
Drawings
FIG. 1 coating scheme one employed in comparative examples 3-5 of the present application.
FIG. 2 shows a second coating scheme employed in examples 1 to 3 of the present application.
FIG. 3 coating scheme III employed in comparative examples 6-7 of the present application.
Detailed Description
The application is further described in connection with the following examples which are provided solely for the purpose of better illustrating the technical solution of the application and are not intended to limit the claims. The application is not limited to the specific examples and embodiments described herein. Further modifications and improvements may readily occur to those skilled in the art without departing from the spirit and scope of the application.
Existing lean burn engine exhaust treatment systems include separate PNA units and SCR units, where the PNA units oxidize 40% -90% of the NO to NO 2 Thereby leading to NO and NO 2 The ratio is much less than 1:1, impeding the rapid SCR reaction. The application coats PNA catalyst and SCR catalyst on different areas of the same monolithic substrate to form a catalyst with low temperature NO X SCR catalyst with adsorption function and NO increasing on substrate 2 Reduction catalyst coating for oxidizing more than 90% of NO to NO 2 Re-establishmentReducing to NO, thereby regulating NO and NO 2 The ratio is close to 1:1, promoting rapid SCR reaction.
The application provides a low-temperature NO X The adsorption function SCR catalyst adopts a flow-through monolithic substrate, a partition coating catalyst is arranged on the substrate, the partition coating catalyst comprises a first partition coating, a second partition coating and a third partition coating, wherein the first partition coating is clung to the wall of the substrate and is positioned at the air inlet end of the substrate, the second partition coating is clung to the wall of the substrate and is positioned at the air outlet end of the substrate, the sum of the lengths of the first partition coating and the second partition coating is equal to the total length of the substrate, and the third partition coating is positioned on the second partition coating and has the same length as the second partition coating; the first zone coating comprises a passive nitrogen oxide adsorption catalyst composition and the second zone coating comprises NO 2 Reduction catalyst composition, third zone coating comprising NO X Reducing the catalyst composition; the first zone coating absorbs NO in the tail gas at a temperature below 150 DEG C X And releasing NO above 250 DEG C X The method comprises the steps of carrying out a first treatment on the surface of the The second zone coating layer will NO X NO of a certain proportion of 2 Convert to NO, make NO 2 And the concentration ratio of NO is 0.8-1.2: 1, a step of; the third zone coating layer will NO X Conversion to N 2 。
In some embodiments provided herein, a passive oxynitride adsorption catalyst composition, NO 2 Reduction catalyst composition, NO X The loading ratio of the reduction catalyst composition is 30-50: 10: 95-120. Within this ratio range, it is ensured that the second zone coating will be partially NO 2 Can reduce NO to NO and then convert NO 2 Is adjusted to approximately 1:1.
In some embodiments provided by the present application, the sum of the third zone coating and the second zone coating thickness is equal to the first zone coating thickness.
In some embodiments provided herein, the passive nox adsorber catalyst composition in the first zone coating has an loading of from 30 to 50g/L; NO in the second zone coating 2 The loading of the reduction catalyst composition was 10.+ -.2 g/L; NO in the third zone coating X The loading of the reduction catalyst composition is 95-120 g/L. Passive oxynitride in the first zone coatingThe loading of the compound adsorption catalyst composition needs to balance low-temperature adsorption performance and system back pressure, so the loading is set to be 30-50 g/L, and when the loading is lower than 30g/L, the NO is discharged from the cold start tail of the engine X Can not be fully adsorbed, and the NO can be further reduced by increasing the loading capacity X Concentration, above 50g/L, of cold start NO X The conversion efficiency is not further improved, and the back pressure of the system is increased to influence the fuel economy of the engine. Second zone coating NO 2 The loading of the reduction catalyst composition was controlled to 10.+ -.2 g/L, which is the main concern for NO 2 Is not limited, and the reduction efficiency of the catalyst is improved.
In some embodiments of the present application, the substrate is one of cordierite, silicon carbide, and a metal material.
In some embodiments of the present application, the metal material is one of Fe-Cr-Ni alloy, co-Cr-Ni alloy, and Ni-Cr-Mo alloy.
In some embodiments provided herein, a passive oxynitride adsorption catalyst composition includes a precious metal active ingredient that is at least one of Pd, ag, co, and a first adsorptive refractory carrier that is a first molecular sieve or metal oxide. The first molecular sieve refers to one of a small pore molecular sieve with an eight-membered ring structure, a medium pore molecular sieve with a ten-membered pore structure and a large pore molecular sieve with a twelve-membered ring structure, and the first molecular sieve can further refer to one of BEA, FAU, MFI, CHA, LTA, AEI, FER, MCM, in particular to one of Beta, HEBA, SSZ-13, ZSM-5, SSZ-39 and HZSM-11. The first molecular sieve has a grain size of 0.01-10 μm and Si/al=1-30. Further, the grain size of the first molecular sieve is 100-1000 nm. The metal oxide is one of gamma-alumina, cerium oxide, praseodymium oxide, zirconium oxide and tungsten oxide and its composite oxide.
In some embodiments provided herein, the passive oxynitride adsorption catalyst composition further comprises a base metal or a rare earth metal, at least one of the base metals being Mn, co, zr, ni, the rare earth metal being Ce or La.
Preferably, the noble metal content is from 0.1wt% to 5wt% of the passive nox adsorber catalyst composition and the base metal is from 0.1wt% to 1wt% of the passive nox adsorber catalyst composition.
In some embodiments of the application provided, NO 2 The reduction catalyst composition comprises NO 2 Reducing the active ingredient and a second adsorptive refractory carrier, NO 2 The reduction active component is one or more of ferric oxide, cobalt oxide, copper oxide, barium oxide, calcium oxide, magnesium oxide, strontium oxide, tin oxide and germanium oxide, and the second adsorptive refractory carrier is silicon oxide or gamma-alumina. NO (NO) 2 The reduction catalyst composition is preferably a symbiotic mixture of at least one of iron oxide, cobalt oxide, copper oxide, barium oxide, calcium oxide, magnesium oxide and one or two of silicon oxide and gamma-alumina.
In some embodiments of the application provided, NO X The reduction catalyst composition comprises NO X Reducing the active ingredient and a third adsorptive refractory carrier, NO X The reducing active ingredient is one or more of Cu, mn, V, fe, co, W, ni, zn, ti, cr, Y, zr, nb, mo, and the third adsorptive refractory carrier comprises one or a symbiotic mixture of analcite, chabazite, heulandite, stilbite, erionite, mordenite, calcium zeolite, and sodium zeolite. More preferably, the third adsorptive refractory carrier is one or a symbiotic mixture of BEA, FAU, MFI, CHA, LTA, AEI, MOR, KFI, ROH frameworks, NO X The reducing active ingredient is a symbiotic mixture of one or more of Cu, fe, W, ti, zr, mo.
In a second aspect, the present application provides a method comprising providing a low temperature NO X A lean burn engine tail gas treatment device of an SCR catalyst with an adsorption function. With the composite catalyst provided by the present application, NO PNA unit is added, preferably, the composite catalyst comprises a catalyst having low-temperature NO X The lean-burn engine tail gas treatment device of the SCR catalyst with the adsorption function is provided with a DOC unit, a DPF unit and a low-temperature NO unit according to the tail gas flowing direction X An adsorption function SCR catalyst unit and an ASC unit.
The following table shows the low temperature NO provided by the application X Adsorption-functional SCR catalysts examples 1 to 3 and comparative examples 1 to 7Parameter table for each coating.
TABLE 1
Table 1 (subsequent)
Example 1:
the present embodiment provides a method for generating NO with low temperature X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: palladium nitrate is added into FER microporous molecular sieve slurry with Si/Al=25 and grain size of 800nm, after being stirred uniformly, 10% of alumina binder is added, and water is added to adjust the solid content of the slurry to 30%, so as to obtain first slurry. The first slurry was applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2 mils, a length of 5 inches, and a diameter of 12 inches from the inlet end in a top feed, 40Hz negative pressure suction mode, with a dry load of 30g/L, a length of 1.5 inches, and calcined in air at 550 c after drying to form a first zone coating.
S2: mixing gamma-alumina with particle size of 1-3 microns with water to obtain alumina suspension, adding nanometer barium oxide colloid suspension in the weight ratio of alumina to barium oxide of 6:4, and stirring to obtain the second slurry. And (3) coating the second slurry to the other end of the straight-through cordierite substrate from the air outlet end in a mode of feeding at the upper side and sucking at a negative pressure of 40Hz, wherein the coating length is 3.5 inches, the uploading dry weight is 10g/L, drying and calcining in air at 550 ℃ to form a second zone coating, as shown in figure 2, wherein the sum of the lengths of the first zone coating and the second zone coating is the total length of the substrate, and the thickness of the first zone coating is larger than that of the second zone coating.
S3: adding water into SSZ-39 molecular sieve with Cu content of 3.5%, stirring and dispersing for 30min, then adding 5% of alumina binder, adding water and regulating to solid content to 30%, thus obtaining third slurry. And (3) coating third slurry on the surface of the second zone coating from the air outlet end in a mode of feeding and negative pressure suction at 40Hz, wherein the coating length is 3.5 inches, covering the whole second zone coating, drying the third slurry with the uploading dry weight of 100g/L, and calcining in air at 550 ℃ to form a third zone coating, thus obtaining the catalyst product, and the catalyst product is marked as catalyst No. 2.
Example 2:
the present embodiment provides a method for generating NO with low temperature X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: silver nitrate is added into SSZ-13 microporous molecular sieve slurry with atomic ratio Si/Al=14 and grain size of 100nm, after being stirred uniformly, 10 percent of alumina binder is added, and water is added to adjust the solid content of the slurry to 30 percent, so as to obtain first slurry. The first slurry was applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2 mils, a length of 5 inches, and a diameter of 12 inches, with a dry weight of 40g/L and a length of 2 inches, from the inlet end, in a 40Hz negative pressure suction mode, and dried and calcined in air at 550℃ to form a first zone coating.
S2: mixing gamma-alumina with particle size of 1-3 μm with water to obtain alumina suspension, adding nano ferric oxide suspension according to the mass ratio of 3:7 of alumina to ferric oxide, and stirring uniformly to obtain second slurry. And (3) coating the second slurry to the other end of the straight-through cordierite substrate from the air outlet end in a mode of feeding at the upper side and sucking at a negative pressure of 40Hz, wherein the coating length is 3 inches, the uploading dry weight is 10g/L, drying and calcining in air at 550 ℃ to form a second zone coating, wherein the sum of the lengths of the first zone coating and the second zone coating is the total length of the substrate, and the thickness of the first zone coating is larger than that of the second zone coating, as shown in figure 2.
S3: adding water into BEA molecular sieve with D50 of 5-8 μm and Fe of 5.2%, stirring and dispersing for 30min, then adding 10% of alumina binder, adding water and regulating the solid content to 30%, thus obtaining third slurry. And (3) coating third slurry on the surface of the second area coating from the air outlet end in a mode of feeding at the upper part and sucking at a negative pressure of 40Hz, wherein the coating length is 3.5 inches, covering the whole second area coating, drying the third slurry with the uploading dry weight of 120g/L, and calcining in air at 550 ℃ to form the third area coating, thus obtaining the catalyst product.
Example 3:
the present embodiment provides a method for generating NO with low temperature X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: palladium nitrate is added into FER microporous molecular sieve slurry with Si/Al=25 and grain size of 800nm, after being stirred uniformly, 10% of alumina binder is added, and water is added to adjust the solid content of the slurry to 30%, so as to obtain first slurry. From the air inlet end, the slurry was applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2mil, a length of 5 inches, and a diameter of 12 inches, with a dry load of 35g/L, a length of 2 inches, and calcined in air at 550 ℃ after drying, in a 40Hz negative pressure suction mode, to form a first zone coating.
S2: mixing gamma-alumina with particle size of 1-3 μm with water to obtain alumina suspension, adding nano barium oxide colloid suspension according to the mass ratio of alumina to barium oxide of 6:4, and stirring uniformly to obtain the second slurry. And (3) coating the second slurry to the other end of the straight-through cordierite substrate from the air outlet end in a mode of feeding at the upper side and sucking at a negative pressure of 40Hz, wherein the coating length is 2 inches, the uploading dry weight is 10g/L, drying and calcining in air at 550 ℃ to form a second zone coating, wherein the sum of the lengths of the first zone coating and the second zone coating is the total length of the substrate, and the thickness of the first zone coating is larger than that of the second zone coating.
S3: adding water into SSZ-39 molecular sieve containing Cu 3.5%, stirring and dispersing for 30min, then adding 5% of alumina binder, adding water and regulating the solid content to be 28%, thus obtaining slurry. And (3) coating third slurry on the surface of the second area coating from the air outlet end in a mode of feeding at the upper part and sucking at a negative pressure of 40Hz, wherein the coating length is 3.5 inches, covering the whole second area coating, drying the third slurry with the uploading dry weight of 95g/L, and calcining in air at 550 ℃ to form the third area coating, thus obtaining the catalyst product.
Comparative example 1:
this comparative example provides a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
SSZ-39 molecular sieve with D50 of 5-8 μm and Cu content of 3.2wt.% is added with water, stirred and dispersed for 30min, then 5% alumina binder (hydrated alumina, TREO oxide content of 73.60%) is added, and water is added to adjust the solid content to 30%, thus obtaining slurry. And (3) coating the slurry on a through cordierite ceramic carrier with 600 meshes, a wall thickness of 3.2mil, a length of 5 inches and a diameter of 12 inches in a mode of negative pressure suction at a 40Hz upper feeding and air outlet end, drying, and calcining in air at 550 ℃ to obtain the catalyst product.
Comparative example 2:
this comparative example provides a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
adding water into BEA molecular sieve containing 4.0% of Fe, stirring and dispersing for 30min, then adding 10% of alumina binder, adding water and regulating the solid content to be 32%, thus obtaining slurry. The slurry was applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2 mils, a length of 5 inches, and a diameter of 12 inches by means of a 40Hz negative pressure suction at the upper feed and exit ends. Drying and calcining in air at 550 ℃ to obtain the catalyst product.
Comparative example 3:
this comparative example provides a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: palladium nitrate is added into FER microporous molecular sieve slurry with Si/Al=25, grain size of 800nm and molecular sieve D50 of 5-8 mu m, after being stirred uniformly, 10% of alumina binder is added, and water is added to adjust the solid content to 30%, so as to obtain first slurry. The first slurry was uniformly applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2mil, a length of 5 inches, and a diameter of 12 inches by means of a 40Hz negative pressure suction at the upper feed and exit ends, dried at an upload dry weight of 35g/L, and calcined in air at 550 c to form a first zone coating having a precious metal content of 0.45wt%.
S2: mixing gamma-alumina with particle size of 1-3 μm with water to obtain alumina suspension, adding nano barium oxide colloid suspension according to the mass ratio of alumina to barium oxide of 7:3, and stirring uniformly to obtain second slurry with solid content of 30%. And uniformly coating the second slurry on the surface of the first area coating in a mode of negative pressure suction at the upper feeding end and the air outlet end of 40Hz, wherein the uploading dry weight is 10g/L, and calcining in air at 550 ℃ after drying to form the second area coating.
S3: adding water into a commercially available SSZ-39 molecular sieve with the D50 of 5-8 mu m and the Cu content of 3.5%, stirring and dispersing for 30min, then adding 5% of an alumina binder, and adding water to adjust the solid content to 30%, thus obtaining third slurry. Uniformly coating the third slurry on the surface of the second area coating in a mode of negative pressure suction at the upper feeding end and the air outlet end of 40Hz, drying the third slurry at the dry weight of 95g/L, and calcining the third slurry in air at 550 ℃ to form a third area coating, thus obtaining a catalyst product, and marking the catalyst product as catalyst No. 1.
Comparative example 4:
this comparative example provides a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: silver nitrate is added into gamma-alumina suspension with the average particle size of 100nm, after being stirred uniformly, 10 percent of alumina binder is added, and water is added to adjust the solid content to 28 percent, so as to obtain first slurry. The first slurry was uniformly applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2mil, a length of 5 inches, and a diameter of 12 inches with an upload dry weight of 50g/L by means of a 40Hz negative pressure suction at the upper feed and outlet ends. After drying, the first zone coating was formed by calcination in air at 550 ℃.
S2: mixing gamma-alumina with particle size of 1-3 μm with water to obtain alumina suspension, adding nanometer barium oxide colloid suspension according to the mass ratio of alumina to barium oxide of 6:4, and stirring uniformly to obtain second slurry. And uniformly coating the second slurry on the surface of the first area coating in a mode of negative pressure suction at the upper feeding end and the air outlet end of 40Hz, wherein the uploading dry weight is 10g/L, and calcining in air at 550 ℃ after drying to form the second area coating.
S3: the BEA molecular sieve containing 5.2wt% fe was dispersed by adding water with stirring for 30 minutes, then 10% alumina binder was added, and water was added to adjust to 30% solids to obtain a third slurry. And uniformly coating the third slurry on the surface of the second area coating in a mode of negative pressure suction at the upper feeding end and the air outlet end of 40Hz, drying the third slurry at the dry weight of 115g/L, and calcining the third slurry in air at 550 ℃ to form a third area coating, thus obtaining the catalyst product.
Comparative example 5:
this comparative example provides a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: adding cobalt oxide into SSZ-13 microporous molecular sieve slurry with Si/Al=14 and grain size of 200nm, stirring uniformly, and adding water to adjust the solid content of the slurry to 30% to obtain first slurry. The first slurry was uniformly applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2mil, a length of 5 inches, and a diameter of 12 inches by means of a 40Hz negative pressure suction at the upper feed and exit ends, dried at a dry weight of 50g/L, and calcined in air at 550 c to form a first zone coating.
S2: mixing gamma-alumina with particle size of 1-3 μm with water to obtain alumina suspension, adding nanometer barium oxide colloid suspension according to the mass ratio of alumina to barium oxide of 6:4, and stirring uniformly to obtain second slurry. And uniformly coating the second slurry on the surface of the first area coating in a mode of negative pressure suction at the upper feeding end and the air outlet end of 40Hz, wherein the uploading dry weight is 10g/L, and calcining in air at 550 ℃ after drying to form the second area coating.
S3: adding water into SSZ-39 molecular sieve containing Cu 3.5%, stirring and dispersing for 30min, then adding 5% of alumina binder, adding water and regulating the solid content to 30%, thus obtaining third slurry. And uniformly coating the third slurry on the surface of the second area coating in a mode of negative pressure suction at the upper feeding end and the air outlet end of 40Hz, drying the third slurry with the dry weight of 95g/L, and calcining the third slurry in air at 550 ℃ to form a third area coating, thus obtaining the catalyst product.
Comparative example 6:
this comparative example provides a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: silver nitrate is added into SSZ-13 microporous molecular sieve slurry with Si/Al=14 and grain size of 200nm, after being stirred uniformly, 10 percent of alumina binder is added, and water is added to adjust the solid content of the slurry to 30 percent. From the air inlet end, the slurry was applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2mil, a length of 5 inches, and a diameter of 12 inches, with a dry load of 45g/L and a length of 2.5 inches, in a top feed, 40Hz negative pressure suction, and calcined in air at 550℃after drying to form a first zone coating.
S2: mixing gamma-alumina with particle size of 1-3 μm with water to obtain alumina suspension, adding nano ferric oxide suspension according to the mass ratio of 3:7 of alumina to ferric oxide, and stirring uniformly to obtain a second slurry. The second slurry was applied to the other end of the flow-through cordierite substrate from the gas outlet end in a top feed, 40Hz negative pressure suction, with a 2.5 inch length, 10g/L dry weight, and dried and calcined in air at 550 c to form a second zone coating, as shown in fig. 3, where the sum of the first and second zone coating lengths is the total substrate length, and the two thicknesses are the same.
S3: adding water into BEA molecular sieve containing 5.2% of Fe, stirring and dispersing for 30min, then adding 10% of alumina binder, adding water and regulating the solid content to be 30%, thus obtaining third slurry. And (3) coating the third slurry on the surfaces of the first area coating layer and the second area coating layer from the air inlet end in a mode of feeding at the upper part and sucking at the negative pressure of 40Hz, wherein the coating length is 5 inches, the uploading dry weight is 115g/L, and calcining in air at 550 ℃ after drying to form the third area coating layer, thus obtaining the catalyst product.
Comparative example 7:
this comparative example provides a low temperature NO X The preparation method of the SCR catalyst with the adsorption function comprises the following steps:
s1: palladium nitrate is added into FER microporous molecular sieve slurry with Si/Al=25 and grain size of 800nm, after being stirred evenly, 10 percent of alumina binder is added, and water is added to adjust the solid content of the slurry to 30 percent. From the air inlet end, the slurry was applied to a through-type cordierite substrate having a mesh size of 600, a wall thickness of 3.2mil, a length of 5 inches, and a diameter of 12 inches, at a dry weight of 30/L, a length of 3.5 inches, and calcined in air at 550 ℃ after drying, in a 40Hz negative pressure suction mode, to form a first zone coating.
S2: mixing gamma-alumina with particle size of 1-3 μm with water to obtain alumina suspension, adding nano ferric oxide suspension according to the mass ratio of 3:7 of alumina to ferric oxide, and stirring uniformly to obtain second slurry. And (3) coating the second slurry to the other end of the straight-through cordierite substrate from the air outlet end in a mode of feeding at the upper part and sucking at a negative pressure of 40Hz, wherein the coating length is 2 inches, the uploading dry weight is 10g/L, drying and calcining in air at 550 ℃ to form a second zone coating, wherein the sum of the lengths of the first zone coating and the second zone coating is the total length of the substrate, and the thicknesses of the first zone coating and the second zone coating are the same.
S3: adding water into SSZ-39 molecular sieve containing Cu 3.5%, stirring and dispersing for 30min, then adding 5% of alumina binder, adding water and regulating the solid content to be 28%, thus obtaining third slurry. And (3) coating the third slurry on the surfaces of the first area coating layer and the second area coating layer from the air inlet end in a mode of feeding at the upper part and sucking at the negative pressure of 40Hz, wherein the coating length is 5 inches, the uploading dry weight is 95g/L, and calcining in air at 550 ℃ after drying to form a third area coating layer, thus obtaining the catalyst product, and the catalyst product is marked as catalyst No. 3.
After the catalyst products obtained in 3 examples and 7 comparative examples of the present application were subjected to a hydrothermal aging test at 650℃for 100 hours, test samples having a diameter of 1 inch and a length of 5 inches were drilled, respectively, to conduct a steady-state performance test. The experimental conditions are shown in table 2. The temperature rising rate is set to be 6 ℃/min in the test process, the temperature is raised to 500 ℃, and second acquisition data of the concentration of each gas phase component at the inlet and the outlet are continuously recorded.
Table 2 steady state performance test atmosphere conditions
According to the inlet NO concentration and the outlet NO 2 Concentration and outlet N 2 The ratio of the result of subtracting the outlet NO concentration from the sum of 2 times the O concentration is NO X Conversion rate. The following table shows the NO of the catalyst articles obtained in the examples and comparative examples X Conversion properties. Cold start NO X Adsorption efficiency was defined as the first time the inlet temperature reached 200 ℃ from the beginning.
TABLE 3 steady state performance test results
Results: comparative example 1 is a full length Cu-SSZ-39 catalyst and comparative example 2 is a full length Fe-BEA catalyst, the advantage of comparative example 1 over comparative example 2 is mainly better low temperature zone efficiency, but if under more stringent regulatory restrictions, at cold start (below 200 ℃ C.), there is still some NO X And the emission is easy to exceed the standard. It is therefore desirable to further increase the conversion efficiency in the low temperature zone. The advantages of comparative example 2 are mainly that the efficiency in the high temperature zone (. Gtoreq.300 ℃) is better than that of the copper-based catalyst, and are not elaborated on in the present application.
The third zone coating of example 1, example 3, comparative example 5, comparative example 7 is all Cu-SSZ-39, which has the main effect of converting NO released after adsorption of the first zone coating X And the second zone coating partially reduced NO. The first zone coating and the second zone coating of comparative examples 3 and 5 are of full coating height, while the second zone coating and the third zone coating of examples 1, 3, 7 are 30% -70% and 70% -30% respectively and different catalytic materials, since the second zone coating of comparative examples 3, 5 completely covers the first zone coating, ensuring that the NO desorbed from the first zone coating X Fully absorbed and catalytically reduced by the second zone coating, ensures NO 2 And NO in a proper proportion, thusThe conversion efficiency of comparative examples 3 and 5 was relatively improved. Whereas in example 1, example 3, comparative example 7 the first zone coating and the second zone coating are in "flow-through" relationship, partially desorbed NO X Without reduction by the second zone coating, the first zone coating adsorbs NO X During the release process, it is not completely reduced by the second zone coating, but directly enters the third zone coating for NH 3 SCR catalytic reaction, conversion efficiency is slightly lower.
In accordance with the examples described above in comparative examples 4, 2, and 6, the first zone coating and the second zone coating of examples 2 and 6 are in "flow-through" relationship, partially desorbed NO X Without reduction by the second zone coating, the first zone coating adsorbs NO X During the release process, it is not completely reduced by the second zone coating, but directly enters the third zone coating for NH 3 SCR catalytic reaction, therefore, conversion efficiency is slightly lower.
Both sulfur poisoning tests and regeneration tests of the samples were performed in a fixed bed quartz reactor. N at 600 DEG C 2 Pretreating under atmosphere for 30min, then cooling the catalyst to 250deg.C, and introducing 50ppm SO 2 、5％O 2 、10％H 2 O，N 2 As equilibrium gas, hold for 40min, space velocity (GHSV) of 76000mL g cat -1 ·h -1 Finally, the sulfated SCR catalyst is obtained. Catalyst regeneration desulfurization is carried out at 550℃at 500ppm NH 3 、500ppmNO、10％O 2 、8％CO 2 、7％H 2 O and N 2 And regenerating the catalyst in the SCR atmosphere serving as the balance gas for 30min, wherein the airspeed is the same as that of the catalyst. After completion of sulfur poisoning and regeneration tests, steady state performance tests were performed using the simulated gases of table 2. The test procedure is as above, and the NO of the catalyst is calculated X Conversion efficiency. Table 4 shows NO of the catalyst article X Conversion properties. Cold start NO X Adsorption efficiency was defined as the first time the inlet temperature reached 200 ℃ from the beginning.
TABLE 4 test results of catalyst articles provided by the application before and after sulfur poisoning
As shown in table 4, coating scheme one (comparative example 3, comparative example 4, comparative example 5) employed a layered design with a first zone coating having a greater reaction interface with a second zone coating than coating scheme two and coating scheme three. And, since the second zone coating separates the first zone coating containing noble metal having oxidizing ability from the third zone coating, the first zone coating generates NO 2 Is effectively reduced, thereby avoiding NO 2 Escape direct with NH 3 Contact is made to reduce N 2 And (3) generating O. From the steady state performance test results, it can be seen that the outlet of the catalyst involved in coating scheme one is at the highest N 2 The O concentration was much lower than coating scheme two (example 1, example 2, example 3), coating scheme three (comparative example 6, comparative example 7).
Coating scheme two (example 1, example 2, example 3) provides a first zone coating on the inlet end and directly in contact with the exhaust gas, thus having better low temperature adsorptivity. At test temperatures below 175℃the NO X The conversion efficiency is high. After the temperature is higher than 200 ℃, the contact surface of the catalyst reduction layer limited by the scheme 2 is smaller, and NO is contained in the catalyst reduction layer at the same temperature X The conversion efficiency is slightly lower.
Coating protocol III (comparative example 6, comparative example 7) the first zone coating was applied to the substrate to avoid SO 2 Oxidized with NH 3 Or the active center in the catalyst forms stable sulfur species to cover the catalyst surface to reduce the catalytic reduction activity, thereby the catalyst product has better sulfur resistance than the coating scheme II, and NO after the light-off temperature of the surface catalyst is reached X The conversion efficiency is slightly higher.
While the application has been described with respect to the preferred embodiments, it will be understood that the application is not limited thereto, but is capable of modification and variation without departing from the spirit of the application, as will be apparent to those skilled in the art.

Claims (9)

1. NO with low temperature X The adsorption function SCR catalyst adopts a flow-through type monolithic substrate, and is characterized in that: the catalyst product adopts a flow-through monolithic substrate, a partition coating catalyst is arranged on the substrate, the partition coating catalyst comprises a first partition coating, a second partition coating and a third partition coating, wherein the first partition coating is clung to the wall of the substrate and is positioned at the air inlet end of the substrate, the second partition coating is clung to the wall of the substrate and is positioned at the air outlet end of the substrate, the sum of the lengths of the first partition coating and the second partition coating is equal to the total length of the substrate, and the third partition coating is positioned on the second partition coating and has the same length as the second partition coating; the first zone coating comprises a passive nitrogen oxide adsorption catalyst composition and the second zone coating comprises NO 2 A reduction catalyst composition, the third zone coating comprising NO X Reducing the catalyst composition; the first zone coating absorbs NO in the tail gas at a temperature of less than 150 DEG C X And releasing NO above 250 DEG C X The method comprises the steps of carrying out a first treatment on the surface of the The second zone coating layer will NO X NO of a certain proportion of 2 Convert to NO, make NO 2 And the concentration ratio of NO is 0.8-1.2: 1, a step of; the third zone coating layer will NO X Conversion to N 2 ；
Passive oxynitride adsorption catalyst composition and NO 2 Reduction catalyst composition, NO X The loading ratio of the reduction catalyst composition is 30-50: 10: 95-120.
2. The method of claim 1 having low temperature NO X The SCR catalyst with the adsorption function is characterized in that: the loading capacity of the passive oxynitride adsorption catalyst composition in the first zone coating is 30-50 g/L; NO in the second zone coating 2 The loading of the reduction catalyst composition was 10.+ -.2 g/L; NO in the third zone coating X The loading of the reduction catalyst composition is 95-120 g/L.
3. The method of claim 1 having low temperature NO X The SCR catalyst with the adsorption function is characterized in that: the base material is one of cordierite, silicon carbide and metal materials.
4. A process according to claim 3 having low temperature NO X The SCR catalyst with the adsorption function is characterized in that: the metal material is one of Fe-Cr-Ni alloy, co-Cr-Ni alloy and Ni-Cr-Mo alloy.
5. The method of claim 1 having low temperature NO X The SCR catalyst with the adsorption function is characterized in that: the passive oxynitride adsorption catalyst composition comprises a noble metal active ingredient and a first adsorptive refractory carrier, wherein the noble metal active ingredient is at least one of Pd and Ag, and the first adsorptive refractory carrier is a first molecular sieve or metal oxide.
6. The method of claim 5 having low temperature NO X The SCR catalyst with the adsorption function is characterized in that: the passive oxynitride adsorption catalyst composition further comprises a base metal or a rare earth metal, wherein the base metal is at least one of Mn, co, zr, ni, and the rare earth metal is Ce or La.
7. The method of claim 1 having low temperature NO X The SCR catalyst with the adsorption function is characterized in that: the NO 2 The reduction catalyst composition comprises NO 2 Reducing the active ingredient and a second adsorptive refractory carrier, said NO 2 The reduction active component is one or more of ferric oxide and barium oxide, and the second adsorptive refractory carrier is silicon oxide or gamma-alumina.
8. The method of claim 1 having low temperature NO X The SCR catalyst with the adsorption function is characterized in that: the NO X The reduction catalyst composition comprises NO X Reducing the active ingredient and a third adsorptive refractory carrier, said NO X The reducing active ingredient is one or more of Cu and Fe, and the third adsorptive refractory carrier comprises one or a symbiotic mixture of analcite, chabazite, heulandite, stilbite, erionite, mordenite, calcium zeolite and sodium zeolite.
9. A lean burn engine exhaust treatment device comprising a low temperature NO according to any one of claims 1 to 8 X An SCR catalyst with adsorption function.
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CN114433202A (en) * 2021-12-23 2022-05-06 惠州市瑞合环保科技有限公司 Diesel engine tail gas purification SCR catalyst and coating process thereof

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CN107106982A (en) * 2014-11-19 2017-08-29 庄信万丰股份有限公司 Combination S CR and PNA is controlled for discharged at lower temperature
CN110573235A (en) * 2017-04-24 2019-12-13 庄信万丰股份有限公司 Passive NOxAdsorbent and process for producing the same
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