Multifunctional catalyst and preparation method thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a multifunctional catalyst and a preparation method thereof.The multifunctional catalyst comprises a catalyst carrier provided with a first functional area and a second functional area in the axial direction; the first zone coating is arranged on the catalyst carrier corresponding to the first functional zone; the second zone coating is arranged on the catalyst carrier corresponding to the second functional zone; the first functional area is used for active regeneration ignition, the second functional area is used for active regeneration and passive regeneration of soot, and the first functional area and the second functional area are both configured to be used for oxidizing diesel engine tail gas pollutants. According to the multifunctional catalyst, one catalyst carrier is divided into a plurality of functional areas, the size is smaller, and compared with a traditional catalyst for a diesel engine, the cost is reduced by 10% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and particularly relates to a multifunctional catalyst and a preparation method thereof. Background Art

[0002] A diesel engine exhaust purification system typically includes catalyst components such as a DOC, DPF, SCR, and ASC. The diesel oxidation catalyst (DOC) is one of the most important components. The DOC oxidizes CO and HC (hydrocarbons) produced by diesel combustion into CO2 and H2O, raising the exhaust temperature. Furthermore, it converts NO into NO2, which has the ability to oxidize particulate matter captured by the downstream DPF (Diesel Particulate Filter), such as soluble organic fractions (SOF) and soot.

[0003] With increasingly stringent regulations on automobile emissions and rising prices for precious metals used as active sites, reducing the size and cost of DOC / DPF systems is a key issue in current development. Therefore, existing catalysts still need improvement. Summary of the Invention

[0004] The purpose of the present invention is to provide a multifunctional catalyst and a preparation method thereof. The multifunctional catalyst of the present invention divides a catalyst carrier into multiple functional zones, is smaller in size, and reduces the cost by more than 10% compared with traditional diesel engine catalysts.

[0005] A first aspect of the present invention provides a multifunctional catalyst, which includes a catalyst carrier having a first functional zone and a second functional zone along the axial direction, and a first zone coating arranged on the catalyst carrier corresponding to the first functional zone and a second zone coating arranged on the catalyst carrier corresponding to the second functional zone; the first zone coating includes at least one of a first coating, a second coating and a third coating, and the second zone coating includes a fourth coating; the third coating and the fourth coating are each filled in the wall pores of the catalyst carrier in its corresponding functional zone, and the third coating and the fourth coating are formed of the same slurry; the first functional zone is used for active regeneration and ignition, and the second functional zone is used for active and passive regeneration of soot, and the first functional zone and the second functional zone are both configured to oxidize diesel exhaust pollutants.

[0006] In some embodiments of the present invention, the first zone coating includes one of the first coating, the second coating, and the third coating, and the first coating or the second coating is composited on the surface of the catalyst carrier.

[0007] In some embodiments of the present invention, the first zone coating layer includes at least two of the first coating layer, the second coating layer, and the third coating layer, and the coating layers are stacked in a direction perpendicular to the axial direction of the catalyst carrier.

[0008] In some embodiments of the present invention, the second coating layer is composited on the surface of the catalyst carrier, and the first coating layer is composited on the surface of the second coating layer on the side away from the catalyst carrier.

[0009] In some embodiments of the present invention, the thickness of the third coating layer and the fourth coating layer are independently less than or equal to the wall thickness of the corresponding catalyst carrier; and / or the thickness of the first coating layer is 5 μm to 30 μm; and / or the thickness of the second coating layer is 5 μm to 60 μm.

[0010] In some embodiments of the present invention, in the first zone coating, along the axial direction of the catalyst carrier, the coating length of the first coating is smaller than the coating length of the second coating, the coating length of the second coating is ≤ the length of the first functional zone of the catalyst carrier, and the filling length of the third coating is ≤ the length of the first functional zone of the catalyst carrier; and / or, in the second zone coating, along the axial direction of the catalyst carrier, the filling length of the fourth coating is ≤ the length of the second functional zone of the catalyst carrier; and / or, in the catalyst carrier, along its axial direction, the length of the first functional zone is ≤ the length of the second functional zone.

[0011] In some embodiments of the present invention, both the first zone coating and the second zone coating contain precious metals, and the precious metals include at least one of Pt and Pd. Based on the catalyst, the mass ratio of the precious metals Pt:Pd in ​​the coating is between 1:0 and 0:1; and / or, based on the catalyst, the concentration of the precious metals in the coating is ≥2 g / cft; preferably 2 g / cft to 100 g / cft.

[0012] In some embodiments of the present invention, in the first zone coating, the concentration of the precious metal in the first coating is 15 g / cft to 100 g / cft; and / or, the concentration of the precious metal in the second coating is 10 g / cft to 100 g / cft; and / or, the concentration of the precious metal in the third coating is 1 g / cft to 10 g / cft; and / or, in the second zone coating, the concentration of the precious metal in the fourth coating is 1 g / cft to 10 g / cft.

[0013] In some embodiments of the present invention, the concentration of the precious metal in the first coating layer is greater than the concentration of the precious metal in the second coating layer, which is greater than the concentration of the precious metal in the third coating layer.

[0014] In some embodiments of the present invention, the raw materials for forming the first coating, the second coating, the third coating, and the fourth coating each independently include a coating carrier and a precious metal material containing at least one of Pt and Pd, and the coating carrier in the raw materials for forming each coating each independently includes at least one of alumina, modified alumina, cerium oxide, and a cerium-zirconium solid solution.

[0015] In some embodiments of the present invention, the particle size of aluminum oxide in the raw material for forming the first coating layer is 4 μm to 30 μm; and / or the particle size of aluminum oxide in the raw material for forming the second coating layer is 4 μm to 30 μm; and / or the particle size of aluminum oxide in the raw material for forming the third coating layer is 1 μm to 15 μm.

[0016] The second aspect of the present invention also provides a method for preparing the multifunctional catalyst described in the first aspect, and the preparation method includes the following steps: dividing the catalyst carrier into a first functional zone and a second functional zone, and according to the specific setting method of each coating in the first zone coating and the second zone coating, filling the slurry forming the fourth coating or the third coating into the wall holes of the catalyst carrier in the corresponding functional zone through the air inlet end or the air outlet end of the catalyst carrier; coating the slurry forming the second coating on the surface of the catalyst carrier in the corresponding functional zone through the air inlet end of the catalyst carrier; and / or coating the slurry forming the first coating on the surface of the catalyst carrier in the corresponding functional zone through the air inlet end of the catalyst carrier.

[0017] In this invention, the first functional zone ignites fuel injected from the diesel engine's post-injection fuel or from the post-treatment fuel nozzle, raising the catalyst's internal temperature to a regeneration temperature above 550°C. This ignites the soot, leading to a vigorous oxidation reaction and removal. During the non-regeneration period, the first functional zone oxidizes organic pollutants such as HC, CO, and SOFC in diesel engine exhaust. It also oxidizes NO to NO2, increasing the passive regeneration rate of soot.

[0018] In the present invention, the second functional zone is the main capture zone for carbon soot, and is also the active and passive regeneration zone for carbon soot. The coating slurry in the second zone enters the wall of the catalyst carrier, which can improve the distribution of the pores of the wall-flow carrier. It is the main area for filtering diesel exhaust particles, and at the same time, the carbon soot is formed into a filter cake and stored on the wall; when active regeneration occurs, the carbon soot and oxygen react violently (the first functional zone ignites the diesel to increase the temperature); when passive regeneration occurs, the carbon soot and NO2 undergo an oxidation reaction (NO2 is produced by oxidation in the first functional zone). The second functional zone also has the ability to oxidize NO to NO2, and can maintain a higher NO2 concentration in the exhaust direction, maintaining a higher passive regeneration rate. The second functional zone can also oxidize organic pollutants such as HC, CO, SOFC, etc. in diesel exhaust.

[0019] The multifunctional catalyst in this invention is coated on a monolithic wall-flow substrate, resulting in a smaller footprint and over 10% lower cost than traditional diesel engine catalysts. The monolithic catalyst provides soot filtration, specifically PM and PN reduction, as well as soot and ash capture and storage. The catalyst captures and stores soot and ash from diesel engine exhaust, and also allows for regeneration after soot capture.

[0020] The arrangement of the first functional zone and the second functional zone of the multifunctional catalyst in the present invention makes the structural division clearer and facilitates the calibration application.

[0021] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of a cross section of a multifunctional catalyst in an embodiment of the present invention along a direction perpendicular to the axial direction of the catalyst carrier.

[0024] Figure 2 It is a schematic cross-sectional view of a multifunctional catalyst in another embodiment of the present invention along a direction perpendicular to the axial direction of the catalyst carrier.

[0025] Figure 3 It is a schematic cross-sectional view of a multifunctional catalyst in another embodiment of the present invention along a direction perpendicular to the axial direction of the catalyst carrier.

[0026] Figure 4 It is a schematic cross-sectional view of a multifunctional catalyst in another embodiment of the present invention along a direction perpendicular to the axial direction of the catalyst carrier.

[0027] Description of reference numerals:

[0028] 100-Multifunctional catalyst;

[0029] 10-catalyst carrier; 11-first functional zone; 12-second functional zone; 20-first coating layer, 30-second coating layer; 40-third coating layer; 50-fourth coating layer. DETAILED DESCRIPTION

[0030] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0031] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0032] In the description of the embodiments of the present invention, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present invention, "plurality" means more than two, unless otherwise specifically defined.

[0033] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] In the description of the embodiments of the present invention, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exists simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0035] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0036] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0037] Some terms used in the present invention are explained below to facilitate understanding by those skilled in the art.

[0038] DPF: Diesel particulate filter, used to capture particulate matter in exhaust gas. When the mass of captured particulate matter reaches a certain level, passive or active regeneration is required to restore the DPF's ability to capture particulate matter.

[0039] DOC: Diesel oxide catalyst, installed before DPF, is used to convert NO in exhaust gas into NO2, while increasing the exhaust gas temperature and assisting the normal operation of DPF and SCR.

[0040] DDPF: An integrated oxidation trap that is coated with DOC-formulated catalysts and DPF-formulated catalysts in separate areas, taking into account the functions of both.

[0041] DPF high temperature regeneration: The DPF temperature is raised to about 600°C, and the carbon in the DPF is reacted with oxygen to eliminate the DPF carbon.

[0042] DPF passive regeneration: Utilize the principle of NO2 reacting with carbon in DPF to eliminate the carbon intercepted in DPF carbon. NO2 comes from the front DOC, and the maximum proportion of NO2 generated is around 350℃.

[0043] In the present invention, the unit g / cft of the precious metal content represents the precious metal content in the unit volume of the catalyst. For example, the precious metal content in the first coating layer represents the precious metal content of the first coating layer in the unit volume of the first functional zone catalyst, the precious metal content in the second coating layer represents the precious metal content of the second coating layer in the unit volume of the first functional zone catalyst, the precious metal content in the third coating layer represents the precious metal content of the third coating layer in the unit volume of the first functional zone catalyst, and the precious metal content in the fourth coating layer represents the precious metal content of the second functional zone catalyst per volume.

[0044] The first aspect of the present invention provides a multifunctional catalyst, Figures 1 to 4According to the introduction, the multifunctional catalyst 100 includes a catalyst carrier 10 having a first functional zone 11 and a second functional zone 12 along the axial direction, and a first zone coating arranged on the catalyst carrier 10 corresponding to the first functional zone 11 and a second zone coating arranged on the catalyst carrier 10 corresponding to the second functional zone 12; wherein, the first zone coating includes at least one of a first coating 20, a second coating 30 and a third coating 40, and the second zone coating includes a fourth coating 50; the third coating 40 and the fourth coating 50 are each filled in the wall pores of the catalyst carrier 10 in its corresponding functional zone, and the third coating 40 and the fourth coating 50 are formed of the same slurry; the first functional zone 11 is used for active regeneration and ignition; the second functional zone 12 is used for active and passive regeneration of soot; the first functional zone 11 and the second functional zone 12 are both configured to oxidize diesel exhaust pollutants.

[0045] In an embodiment of the present invention, a multifunctional catalyst can effectively reduce HC compounds, CO, NO, PM, and PN in diesel engine exhaust. The multifunctional catalyst includes a catalyst carrier and a coating composited on the surface of the catalyst carrier. The catalyst carrier has a first functional zone and a second functional zone along its axial direction, and the coating includes a first zone coating corresponding to the first functional zone and a second zone coating corresponding to the second functional zone. The first functional zone serves as the diesel engine exhaust intake port, with active regeneration and ignition occurring in the first functional zone, while active and passive soot regeneration can occur in the second functional zone. Both the first and second functional zones function to oxidize diesel engine exhaust pollutants. Diesel engine exhaust pollutants include HC compounds, CO, SOFC, NO, and the like.

[0046] In some embodiments of the present invention, the multifunctional catalyst is formed by coating an integral carrier, and the catalyst as a whole has a soot filtering function, specifically including PM reduction, PN reduction function, and soot and ash capture and storage function. The soot and ash in the diesel engine exhaust are captured and stored by the catalyst.

[0047] In some embodiments of the present invention, the catalyst carrier includes a wall-flow carrier, such as a monolithic wall-flow carrier as the catalyst carrier.

[0048] In some embodiments of the present invention, the material of the catalyst carrier includes one of cordierite, silicon carbide, aluminum titanate, and mullite.

[0049] In some embodiments of the present invention, the end face of the catalyst carrier may be cylindrical, square, annular, etc.

[0050] In some embodiments of the present invention, the catalyst carrier adopts an alternating pore structure.

[0051] In the embodiment of the present invention, the first zone coating includes one of the first coating 20, the second coating 30 and the third coating 40. It can be understood that the first zone coating only contains the first coating 20, in which case the first coating 20 is compounded on the surface of the catalyst support 10; or the first zone coating only contains the second coating 30, in which case the second coating 30 is compounded on the surface of the catalyst support 10. Figure 4 or the first zone coating contains only the third coating 40, at this time the third coating 40 is filled in the wall pores of the catalyst carrier 10 corresponding to the first functional zone 11, that is, the third coating 40 is formed inside the wall of the catalyst carrier 10.

[0052] In an embodiment of the present invention, the second zone coating only contains the fourth coating 50, which can be understood as only the fourth coating 50 being compounded on the catalyst carrier 10 corresponding to the second functional zone 12. At this time, the fourth coating 50 is filled in the wall holes of the catalyst carrier 10 corresponding to the second functional zone 12, that is, the fourth coating 50 is formed inside the wall of the catalyst carrier 10.

[0053] In an embodiment of the present invention, the first zone coating layer includes at least two of a first coating layer 20 , a second coating layer 30 and a third coating layer 40 , and the coating layers are stacked in a direction perpendicular to the axial direction of the catalyst carrier 10 .

[0054] In some embodiments of the present invention, the first zone coating comprises a first coating 20 and a second coating 30 arranged in a stacked manner. In this case, the second coating 30 is composited on the surface of the catalyst carrier 10, and the first coating 20 is composited on the side of the second coating 30 away from the catalyst carrier 10. Figure 1 and Figure 2 shown.

[0055] In an embodiment of the present invention, the thickness of the first coating layer 20 is 5 μm to 30 μm. For example, the thickness of the first coating layer 20 can be one of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, and 30 μm, or any value within the above range.

[0056] In an embodiment of the present invention, the thickness of the second coating layer 30 is 5 μm to 60 μm. For example, the thickness of the second coating layer 30 can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, 56 μm, 57 μm, 58 μm, 59 μm, 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm, 66 μm, 67 μm, 68 μm, 69 μm, 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm, 81 μm, 82 μm, 83 m, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, 60μm or any value that meets the above range.

[0057] In the embodiment of the present invention, the filling thickness of the third coating layer 40 is less than or equal to the wall thickness of the corresponding catalyst carrier 10 .

[0058] In the embodiment of the present invention, the filling thickness of the fourth coating layer 50 is less than or equal to the wall thickness of the corresponding catalyst carrier 10 .

[0059] In an embodiment of the present invention, in the first zone coating, along the axial direction of the catalyst carrier 10, the coating length of the first coating 20 is less than the coating length of the second coating 30, the coating length of the second coating 30 is ≤ the length of the first functional zone 11 of the catalyst carrier 10, and the filling length of the third coating 40 is ≤ the length of the first functional zone 11 of the catalyst carrier. The specific length of each coating can be set according to functional requirements.

[0060] In an embodiment of the present invention, in the second zone coating, along the axial direction of the catalyst carrier 10, the filling length of the fourth coating 50 is ≤ the length of the second functional zone 12 of the catalyst carrier. The specific length of the coating can be set according to functional requirements.

[0061] In the embodiment of the present invention, in the catalyst carrier 10, along the axial direction thereof, the length b of the first functional area 11 is less than the length (ab) of the second functional area 12, see Figure 1 As shown, the specific length of each functional area can be set according to functional requirements without limitation.

[0062] In an embodiment of the present invention, both the first region coating layer and the second region coating layer contain precious metals, and the precious metals include at least one of Pt and Pd.

[0063] In some embodiments of the present invention, based on the multifunctional catalyst, the mass ratio of Pt:Pd in ​​the precious metal is between 1:0 and 0:1. For example, the mass ratio of Pt:Pd in ​​the precious metal coating can be 1:0, 0:1, 1:1, or any other value within the above range.

[0064] In some embodiments of the present invention, the concentration of the precious metal in the coating is ≥ 2 g / cft based on the multifunctional catalyst.

[0065] In some embodiments of the present invention, the concentration of the precious metal in the coating is 2 g / cft to 100 g / cft based on the multifunctional catalyst. For example, the concentration of the precious metal may be 2 g / cft, 3 g / cft, 4 g / cft, 5 g / cft, 6 g / cft, 7 g / cft, 8 g / cft, 9 g / cft, 10 g / cft, 11 g / cft, 12 g / cft, 13 g / cft, 14 g / cft, 15 g / cft, 16 g / cft, 18 g / cft, 20 g / cft, 22 g / cft, 24 g / cft, 25 g / cft, 26 g / cft, 28 g / cft, 30 g / cft, 32 g / cft, 34 g / cft, 35 g / cft, 36 g / cft, 38 g / cft, 40 g / cft, 42 g / cft, 44 g / cft, 45 g / cft, 46 g / cft, 48 g / cft, g / cft, 82g / cft, 84g / cft, 85g / cft, 86g / cft, 88g / cft, 90g / cft, 92g / cft, 94g / cft, 95g / cft, 96g / cft, 98g / cft and 100g / cft or any value meeting the above range.

[0066] In some embodiments of the present invention, in the first zone coating, the concentration of the precious metal in the first coating layer 20 is 15 g / cft to 100 g / cft. For example, the concentration of the precious metal in the first coating layer 20 can be 15 g / cft, 16 g / cft, 17 g / cft, 18 g / cft, 19 g / cft, 20 g / cft, 22 g / cft, 24 g / cft, 25 g / cft, 26 g / cft, 28 g / cft, 30 g / cft, 32 g / cft, 34 g / cft, 35 g / cft, 36 g / cft, 38 g / cft, 40 g / cft, 42 g / cft, 44 g / cft, 45 g / cft, 46 g / cft, 48 g / cft, 50 g / cft, 52 g / cft, 54 g / cft, 55 g / cft, g / cft, 90g / cft, 92g / cft, 94g / cft, 95g / cft, 96g / cft, 98g / cft and 100g / cft or any value meeting the above range.

[0067] In some embodiments of the present invention, in the first zone coating, the concentration of the precious metal in the second coating 30 is 10 g / cft to 100 g / cft. For example, the concentration of the precious metal in the second coating 30 may be 10 g / cft, 11 g / cft, 12 g / cft, 13 g / cft, 14 g / cft, 15 g / cft, 16 g / cft, 17 g / cft, 18 g / cft, 19 g / cft, 20 g / cft, 22 g / cft, 24 g / cft, 25 g / cft, 26 g / cft, 28 g / cft, 30 g / cft, 32 g / cft, 34 g / cft, 35 g / cft, 36 g / cft, 38 g / cft, 40 g / cft, 42 g / cft, 44 g / cft, 45 g / cft, 46 g / cft, 48 g / cft, 50 g / cft , 52g / cft, 54g / cft, 55g / cft, 56g / cft, 58g / cft, 60g / cft, 62g / cft, 64g / cft, 65g / cft, 68g / cft, 70g / cft, 72g / cft, 74g / cft, 75g / cft, 76g / cft, 78g / cft, 80g / cft, 82g / cft, 84g / cft, 85g / cft, 86g / cft, 88g / cft, 90g / cft, 92g / cft, 94g / cft, 95g / cft, 96g / cft, 98g / cft, 100g / cft or any value meeting the above range.

[0068] In some embodiments of the present invention, in the first zone coating, the concentration of the precious metal in the third coating layer 40 is 1 g / cft to 10 g / cft. For example, the concentration of the precious metal in the third coating layer 40 can be one of 1 g / cft, 2 g / cft, 3 g / cft, 4 g / cft, 5 g / cft, 6 g / cft, 7 g / cft, 8 g / cft, 9 g / cft, and 10 g / cft, or any value within the above range.

[0069] In some embodiments of the present invention, the concentration of precious metals in the first coating layer 20 is greater than the concentration of precious metals in the second coating layer 30, which is greater than the concentration of precious metals in the third coating layer 40. Of course, it can also be understood that the concentration of precious metals in the slurry forming the first coating layer 20 is greater than the concentration of precious metals in the slurry forming the second coating layer 30, which is greater than the concentration of precious metals in the slurry forming the third coating layer 40.

[0070] In some embodiments of the present invention, in the second zone coating, the concentration of the precious metal in the fourth coating layer 50 is 1 g / cft to 10 g / cft. For example, the concentration of the precious metal in the fourth coating layer 50 can be one of 1 g / cft, 2 g / cft, 3 g / cft, 4 g / cft, 5 g / cft, 6 g / cft, 7 g / cft, 8 g / cft, 9 g / cft, and 10 g / cft, or any value within the above range.

[0071] In the embodiment of the present invention, the raw materials for forming the first coating layer 20 , the second coating layer 30 , the third coating layer 40 and the fourth coating layer 50 independently include a coating carrier and a precious metal material containing at least one of Pt and Pd.

[0072] In some embodiments of the present invention, the noble metal material includes at least one of platinum nitrate, palladium nitrate, platinum chloride, palladium chloride, platinum acetate, and palladium acetate.

[0073] In some embodiments of the present invention, the coating carrier in the raw materials forming each coating layer independently includes at least one of alumina, modified alumina, cerium oxide, and a cerium-zirconium solid solution. For example, the coating carrier can be alumina, a mixed carrier of alumina and cerium oxide, or a mixed carrier of alumina and a cerium-zirconium solid solution.

[0074] In some embodiments of the present invention, the particle size of aluminum oxide in the raw material for forming the first coating layer 20 is 4 μm to 30 μm. For example, the particle size of aluminum oxide in the raw material for forming the first coating layer can be one of 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, and 30 μm, or any value within the above range.

[0075] In some embodiments of the present invention, the particle size of aluminum oxide in the raw material for forming the second coating layer 30 is 4 μm to 30 μm. For example, the particle size of aluminum oxide in the raw material for forming the second coating layer can be one of 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, and 30 μm, or any value within the above range.

[0076] In some embodiments of the present invention, the particle size of aluminum oxide in the raw material for forming the third coating layer 40 is 1 μm to 15 μm. For example, the particle size of aluminum oxide in the raw material for forming the third coating layer 40 can be one of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, and 15 μm, or any value within the above range.

[0077] In some embodiments of the present invention, the raw materials for forming the first coating layer 20 , the second coating layer 30 , the third coating layer 40 and the fourth coating layer 50 further independently include at least one of a pH adjuster, a binder and a thickener.

[0078] In some embodiments of the present invention, the pH adjuster includes at least one of acetic acid and ammonia water.

[0079] In some embodiments of the present invention, the binder includes at least one of pseudo-boehmite, aluminum sol, silica sol, and silica-alumina sol.

[0080] In an embodiment of the present invention, the thickener includes at least one of hydroxyethyl cellulose, polyacrylic acid, polyurethane, polyvinyl alcohol, gelatin, pectin, and gum arabic.

[0081] In some embodiments of the present invention, the preparation method of the slurry for forming the first coating 20 includes: placing alumina in a beaker, adding deionized water, and stirring to mix uniformly; then adding platinum nitrate solution and palladium nitrate solution, stirring to fully disperse them; then slowly adding pseudo-boehmite, stirring to mix uniformly; then adding acetic acid dropwise to adjust the pH value to 3.0; finally, slowly adding hydroxyethyl cellulose, stirring thoroughly, so that the slurry viscosity increases to 7000 mPa.s.

[0082] In some embodiments of the present invention, the preparation method of the slurry for forming the second coating 30 includes: placing alumina in a beaker, adding deionized water, and stirring to mix uniformly; then adding platinum nitrate solution and palladium nitrate solution, and stirring to fully disperse them; slowly adding pseudo-boehmite, and stirring to mix uniformly; adding acetic acid dropwise to adjust the pH value of the slurry to 3.0; and finally slowly adding hydroxyethyl cellulose and stirring to increase the viscosity of the slurry to 7000 mPa.s.

[0083] In some embodiments of the present invention, the preparation method of the slurry for forming the third coating 40 includes: placing an alumina carrier in a beaker, adding deionized water, and stirring to mix evenly; adding platinum nitrate solution and palladium nitrate solution, and stirring to fully disperse them; slowly adding pseudo-boehmite, and stirring to mix evenly; adding acetic acid dropwise to adjust the pH value of the slurry to 3.0; and finally slowly adding hydroxyethyl cellulose and stirring thoroughly to increase the viscosity of the slurry to 7000 mPa.s.

[0084] It is worth mentioning that the preparation method of the slurry for forming the fourth coating layer 50 in the present invention is the same as the preparation method of the slurry for forming the third coating layer 40 , and the slurries used in the two are exactly the same.

[0085] The second aspect of the present invention provides a method for preparing the multifunctional catalyst described in the first aspect. The key to the preparation method is to divide the catalyst carrier into a first functional zone and a second functional zone, and according to the specific setting method of each coating in the first zone coating and the second zone coating, the slurry forming the fourth coating or the third coating is filled into the wall holes of the catalyst carrier in the corresponding functional zone through the air inlet end or the air outlet end of the catalyst carrier; the slurry forming the second coating is coated on the surface of the catalyst carrier in the corresponding functional zone through the air inlet end of the catalyst carrier; and / or, the slurry forming the first coating is coated on the surface of the catalyst carrier in the corresponding functional zone through the air inlet end of the catalyst carrier.

[0086] In some embodiments of the present invention, see Figure 1 As shown, the slurry forming the fourth coating layer or the third coating layer is filled into the wall holes of the catalyst carrier corresponding to the first functional area and the second functional area through the air inlet end of the catalyst carrier to obtain the fourth coating layer and the third coating layer; the slurry forming the second coating layer is coated on the surface of the catalyst carrier in the first functional area through the air inlet end of the catalyst carrier to obtain the second coating layer; the slurry forming the first coating layer is coated on the surface of the second coating layer through the air inlet end of the catalyst carrier to obtain the first coating layer.

[0087] In some embodiments of the present invention, see Figure 2 As shown, the slurry forming the fourth coating layer is filled into the wall holes of the catalyst carrier corresponding to the second functional zone through the air outlet end of the catalyst carrier to obtain the fourth coating layer; the slurry forming the second coating layer is coated on the surface of the catalyst carrier corresponding to the first functional zone through the air inlet end of the catalyst carrier to obtain the second coating layer; the slurry forming the first coating layer is coated on the surface of the second coating layer through the air inlet end of the catalyst carrier to obtain the first coating layer.

[0088] In some embodiments of the present invention, see Figure 3 As shown, the slurry forming the fourth coating layer or the third coating layer is filled into the wall pores of the catalyst carrier corresponding to the first functional zone and the second functional zone through the air inlet end of the catalyst carrier to obtain the fourth coating layer and the third coating layer; the slurry forming the second coating layer is coated on the surface of the catalyst carrier corresponding to the first functional zone through the air inlet end of the catalyst carrier to obtain the second coating layer.

[0089] In some embodiments of the present invention, see Figure 4As shown, the slurry forming the fourth coating layer is filled into the wall holes of the catalyst carrier corresponding to the second functional zone through the gas outlet end of the catalyst carrier to obtain the fourth coating layer; the slurry forming the second coating layer is coated on the surface of the catalyst carrier corresponding to the first functional zone through the gas inlet end of the catalyst carrier to obtain the second coating layer.

[0090] It is worth mentioning that the first zone coating and the second zone coating are mainly arranged corresponding to the intake channel of the catalyst carrier, specifically arranged on the inner wall surface of the intake channel and inside the pore wall of the catalyst carrier.

[0091] In some embodiments of the present invention, the filling thickness of the slurry forming the fourth coating layer is less than or equal to the wall thickness of the catalyst carrier corresponding to the second functional area based on the wall thickness direction of the catalyst carrier or based on the axial direction perpendicular to the catalyst carrier.

[0092] In some embodiments of the present invention, based on the axial direction of the catalyst carrier, the filling length of the slurry forming the fourth coating layer is less than or equal to the length of the second functional area of ​​the catalyst carrier.

[0093] In some embodiments of the present invention, the filling thickness of the slurry forming the third coating layer is less than or equal to the wall thickness of the catalyst carrier corresponding to the first functional area based on the wall thickness direction of the catalyst carrier or based on the axial direction perpendicular to the catalyst carrier.

[0094] In some embodiments of the present invention, based on the axial direction of the catalyst carrier, the filling length of the slurry forming the third coating layer is less than or equal to the length of the first functional area of ​​the catalyst carrier.

[0095] In some embodiments of the present invention, the coating thickness of the slurry for forming the second coating layer is 5 μm to 60 μm based on the wall thickness direction of the catalyst carrier or based on the axial direction perpendicular to the catalyst carrier. For example, the coating thickness of the slurry for forming the second coating layer can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, One of 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, 60μm or any value that meets the above range.

[0096] In some embodiments of the present invention, based on the axial direction of the catalyst carrier, the coating length of the slurry forming the second coating layer is less than or equal to the length of the first functional area of ​​the catalyst carrier.

[0097] In some embodiments of the present invention, the coating thickness of the slurry forming the first coating layer is 5 μm to 30 μm based on the wall thickness direction of the catalyst carrier or based on the axial direction perpendicular to the catalyst carrier. For example, the coating thickness of the slurry forming the first coating layer can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, or any value that meets the above range.

[0098] In some embodiments of the present invention, based on the axial direction of the catalyst support, the coating length of the slurry forming the first coating layer is shorter than the coating length of the slurry forming the second coating layer.

[0099] In the embodiments of the present invention, the multifunctional catalyst described in the first aspect of the present invention or the multifunctional catalyst prepared by the preparation method described in the second aspect of the present invention can be used as, but not limited to, a catalyst for a diesel engine.

[0100] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following examples are all commercially available or can be obtained through existing methods; the amounts of the experimental reagents used, unless otherwise specified, are the amounts used in conventional experimental procedures; and the experimental methods, unless otherwise specified, are all conventional methods.

[0101] The slurry for forming the first coating layer 20 (hereinafter referred to as slurry A) is prepared by placing alumina with a particle size D50 of 13 μm in a beaker, adding deionized water, and stirring to mix thoroughly; then adding platinum nitrate solution and palladium nitrate solution and stirring to fully disperse them; slowly adding pseudo-boehmite and stirring to mix thoroughly; then gradually adding acetic acid dropwise to adjust the pH of the slurry to 3.0; and finally slowly adding hydroxyethyl cellulose and stirring thoroughly to increase the slurry viscosity to 7000 mPa·s. The total mass of the precious metals platinum and palladium in slurry A accounts for 1.5% of the total weight of slurry A.

[0102] The slurry for forming the second coating layer 30 (hereinafter referred to as slurry B) is prepared by placing alumina with a particle size D50 of 13 μm in a beaker, adding deionized water, and stirring to mix thoroughly; adding platinum nitrate solution and palladium nitrate solution, and stirring to fully disperse them; slowly adding pseudo-boehmite and stirring to mix thoroughly; adding acetic acid dropwise to adjust the pH of the slurry to 3.0; and finally, slowly adding hydroxyethyl cellulose and stirring thoroughly to increase the slurry viscosity to 7000 mPa·s. The total mass percentage of the precious metals platinum and palladium in slurry B is 1.05% by weight of the total weight of slurry B.

[0103] The slurry for forming the third coating layer 40 (hereinafter referred to as slurry C) is prepared by placing an alumina support with a particle size D50 of 7 μm in a beaker, adding deionized water, and stirring to mix thoroughly; adding a platinum nitrate solution and a palladium nitrate solution, and stirring to fully disperse them; slowly adding pseudo-boehmite and stirring to mix thoroughly; adding acetic acid dropwise to adjust the pH of the slurry to 3.0; and finally, slowly adding hydroxyethyl cellulose and stirring thoroughly to increase the slurry viscosity to 7000 mPa·s. The total mass percentage of the precious metals platinum and palladium in slurry C is 0.47% by weight of the total weight of slurry C.

[0104] The slurry for forming the fourth coating layer 50 (hereinafter referred to as slurry D, similar to slurry C) is prepared by placing an alumina support with a particle size D50 of 7 μm in a beaker, adding deionized water, and stirring to mix thoroughly; adding a platinum nitrate solution and a palladium nitrate solution, and stirring to fully disperse them; slowly adding pseudo-boehmite and stirring to mix thoroughly; adding acetic acid dropwise to adjust the pH of the slurry to 3.0; and finally, slowly adding hydroxyethyl cellulose and stirring thoroughly to increase the slurry viscosity to 7000 mPa·s. The total mass percentage of the precious metals platinum and palladium in slurry D is 0.47% by weight of the total weight of slurry D.

[0105] Example 1

[0106] A multifunctional catalyst, the cross-sectional view of which is shown in FIG. Figure 1 As shown, the preparation of the catalyst includes:

[0107] Slurry C was filled into the wall pores of the support corresponding to the first and second functional zones through the air inlet of the wall-flow support. The filling length of slurry C was 90%a, and the filling thickness of slurry C was equal to the wall thickness of the wall-flow support, thereby forming a third coating layer 40 and a fourth coating layer 50. The concentration of the precious metal in the third coating layer 40 and the fourth coating layer 50 was independently 2 g / cft.

[0108] Slurry B was applied to the surface of the wall-flow support corresponding to the first functional zone through the air inlet end of the wall-flow support. The coating thickness of slurry B was 30 μm and the coating length was 40%a, thereby forming a second coating layer 30. The concentration of the precious metal in the second coating layer 30 was 20 g / cft.

[0109] Slurry A was coated on the surface of the second coating layer 30 through the air inlet end of the wall-flow carrier. The coating thickness of slurry A was 20 μm and the coating length was 20%a, thereby obtaining the first coating layer 20. The precious metal concentration in the first coating layer 20 was 32.5 g / cft.

[0110] Example 2

[0111] A multifunctional catalyst, the cross-sectional view of which is shown in FIG. Figure 2 As shown, the preparation of the catalyst includes:

[0112] Slurry C was filled into the wall pores of the wall-flow carrier corresponding to the second functional zone through the gas outlet of the wall-flow carrier. The filling length of slurry C was 55%a, and the filling thickness of slurry C was equal to the wall thickness of the wall-flow carrier, thereby forming a fourth coating 50. The concentration of the precious metal in the fourth coating 50 was 2 g / cft.

[0113] Slurry B was applied to the surface of the wall-flow support corresponding to the first functional zone through the air inlet end of the wall-flow support. The coating thickness of slurry B was 30 μm and the coating length was 40%a, thereby forming a second coating layer 30. The concentration of the precious metal in the second coating layer 30 was 20 g / cft.

[0114] Slurry A was coated on the surface of the second coating layer 30 through the air inlet end of the wall-flow carrier. The coating thickness of slurry A was 20 μm and the coating length was 20%a, thereby obtaining the first coating layer 20. The precious metal concentration in the first coating layer 20 was 32.5 g / cft.

[0115] Example 3

[0116] A multifunctional catalyst, the cross-sectional view of which is shown in FIG. Figure 3 As shown, the preparation of the catalyst includes:

[0117] Slurry C was filled into the wall pores of the support corresponding to the first and second functional zones through the air inlet of the wall-flow support. The filling length of slurry C was 90%a, and the filling thickness of slurry C was equal to the wall thickness of the wall-flow support, thereby forming a third coating layer 40 and a fourth coating layer 50. The concentration of the precious metal in the third coating layer 40 and the fourth coating layer 50 was independently 2 g / cft.

[0118] Slurry B was applied to the surface of the wall-flow support corresponding to the first functional zone through the air inlet end of the wall-flow support. The coating thickness of slurry B was 30 μm and the coating length was 40%a, thereby forming a second coating layer 30. The concentration of the precious metal in the second coating layer 30 was 20 g / cft.

[0119] Example 4

[0120] A multifunctional catalyst, the cross-sectional view of which is shown in FIG. Figure 4 As shown, the preparation of the catalyst includes:

[0121] Slurry C was filled into the wall pores of the wall-flow carrier corresponding to the second functional zone through the gas outlet of the wall-flow carrier. The filling length of slurry C was 55%a, and the filling thickness of slurry C was equal to the wall thickness of the wall-flow carrier, thereby forming a fourth coating 50. The concentration of the precious metal in the fourth coating 50 was 2 g / cft.

[0122] Slurry B was applied to the surface of the wall-flow support corresponding to the first functional zone through the air inlet end of the wall-flow support. The coating thickness of slurry B was 30 μm and the coating length was 40%a, thereby forming a second coating layer 30. The concentration of the precious metal in the second coating layer 30 was 20 g / cft.

[0123] In the present invention, the captured soot can ignite the diesel through the first functional area 11, causing the DDPF to undergo active regeneration. The first functional area 11 cooperates with the second functional area 12 to undergo passive regeneration.

[0124] The first functional zone 11 ignites fuel injected from the diesel engine's post-injection fuel or from the post-treatment fuel injector, raising the catalyst's internal temperature to a regeneration temperature exceeding 550°C. This ignites the soot, leading to a vigorous oxidation reaction and removal. During the non-regeneration period, the first functional zone oxidizes organic pollutants such as HC, CO, and SOFC in diesel engine exhaust. It also oxidizes NO to NO2, increasing the passive regeneration rate of soot.

[0125] The second functional zone 12 is the main capture zone for carbon soot, and is also the active and passive regeneration zone for carbon soot. The coating slurry in the second zone enters the wall of the catalyst carrier, which can improve the distribution of the wall-flow carrier pores. It is the main area for filtering diesel exhaust particles, and at the same time, the carbon soot is formed into a filter cake and stored on the wall; when active regeneration occurs, the carbon soot and oxygen react violently with combustion (the first functional zone 11 ignites the diesel to increase the temperature); when passive regeneration occurs, the carbon soot and NO2 undergo an oxidation reaction (NO2 is produced by oxidation in the first functional zone). The second functional zone 12 also has the ability to oxidize NO to NO2, and can maintain a higher NO2 concentration in the exhaust direction, maintaining a higher passive regeneration rate. The second functional zone 12 can also oxidize organic pollutants such as HC, CO, SOFC, etc. in diesel exhaust.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multifunctional catalyst, characterized in that The catalyst carrier comprises a first functional zone and a second functional zone along the axial direction, and a first zone coating provided on the catalyst carrier corresponding to the first functional zone and a second zone coating provided on the catalyst carrier corresponding to the second functional zone; The first zone coating comprises at least one of a first coating, a second coating and a third coating, and the second zone coating comprises a fourth coating; the third coating and the fourth coating are each filled in the wall pores of the catalyst support in its corresponding functional zone, and the third coating and the fourth coating are formed of the same slurry; The first functional area is used for active regeneration and ignition, and the second functional area is used for active soot regeneration and passive regeneration. The first functional area and the second functional area are both configured to oxidize diesel engine exhaust pollutants.

2. The multifunctional catalyst according to claim 1, wherein The first zone coating comprises one of the first coating, the second coating, and the third coating, The first coating layer or the second coating layer is composited on the surface of the catalyst carrier.

3. The multifunctional catalyst according to claim 1, wherein The first zone coating layer includes at least two of the first coating layer, the second coating layer, and the third coating layer, and the coating layers are stacked in a direction perpendicular to the axial direction of the catalyst carrier.

4. The multifunctional catalyst according to claim 3, wherein The second coating layer is compounded on the surface of the catalyst carrier, and the first coating layer is compounded on the surface of the second coating layer on the side away from the catalyst carrier.

5. The multifunctional catalyst according to claim 1, wherein The thickness of the third coating layer and the fourth coating layer are independently less than or equal to the wall thickness of the catalyst support corresponding thereto; and / or, The thickness of the first coating layer is 5 μm to 30 μm; and / or, The thickness of the second coating layer is 5 μm to 60 μm.

6. The multifunctional catalyst according to claim 1, wherein In the first zone coating, along the axial direction of the catalyst support, the coating length of the first coating is shorter than the coating length of the second coating, the coating length of the second coating is ≤ the length of the first functional zone of the catalyst support, and the filling length of the third coating is ≤ the length of the first functional zone of the catalyst support; and / or, In the second zone coating, along the axial direction of the catalyst carrier, the filling length of the fourth coating is ≤ the length of the second functional zone of the catalyst carrier; and / or, In the catalyst carrier, along the axial direction thereof, the length of the first functional zone is ≤ the length of the second functional zone.

7. The multifunctional catalyst according to claim 1, characterized in that The first zone coating and the second zone coating both contain precious metals, and the precious metals include at least one of Pt and Pd. Based on the catalyst, the mass ratio of the precious metal Pt:Pd in ​​the coating is between 1:0 and 0:1; and / or, The concentration of the noble metal in the coating is ≥ 2 g / cft based on the catalyst; preferably 2 g / cft to 100 g / cft.

8. The multifunctional catalyst according to claim 1, wherein In the first zone coating, the concentration of the precious metal in the first coating is 15 g / cft to 100 g / cft; and / or, the concentration of the precious metal in the second coating is 10 g / cft to 100 g / cft; and / or, the concentration of the precious metal in the third coating is 1 g / cft to 10 g / cft; and / or, In the second zone coating, the concentration of the precious metal in the fourth coating is 1 g / cft to 10 g / cft; Preferably, the concentration of the precious metal in the first coating layer is greater than that in the second coating layer, and the concentration of the precious metal in the third coating layer is greater than that in the third coating layer.

9. The multifunctional catalyst according to claim 1, wherein The raw materials for forming the first coating layer, the second coating layer, the third coating layer, and the fourth coating layer independently include a coating carrier and a precious metal material containing at least one of Pt and Pd, and the coating carrier in the raw materials for forming each coating layer independently includes at least one of alumina, modified alumina, cerium oxide, and a cerium-zirconium solid solution; Preferably, the particle size of aluminum oxide in the raw material for forming the first coating is 4 μm to 30 μm; and / or the particle size of aluminum oxide in the raw material for forming the second coating is 4 μm to 30 μm; and / or the particle size of aluminum oxide in the raw material for forming the third coating is 1 μm to 15 μm.

10. A method for preparing the multifunctional catalyst according to any one of claims 1 to 9, characterized in that: The following steps are involved: The catalyst carrier is divided into a first functional zone and a second functional zone, and according to the specific arrangement of each coating layer in the first zone coating layer and the second zone coating layer, the slurry for forming the fourth coating layer or the third coating layer is filled into the wall pores of the catalyst carrier in the corresponding functional zone through the air inlet end or the air outlet end of the catalyst carrier; Applying the slurry for forming the second coating layer onto the surface of the catalyst support corresponding to the functional area through the air inlet end of the catalyst support; and / or, The slurry for forming the first coating layer is coated on the surface of the catalyst support corresponding to the functional area through the air inlet end of the catalyst support.

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