A carrier structure for a three-way catalyst

Abstract

This invention relates to a carrier structure for a three-way catalytic converter, and pertains to the field of three-way catalytic converters. The carrier body includes an axial gradient structure along the axial airflow direction, characterized by a decreasing pore size gradient and an increasing pore density gradient. The carrier body also has a radial gradient structure along the radial direction away from the center, characterized by an increasing pore size gradient and a decreasing pore density gradient. This application effectively solves the problem of unreasonable flow resistance in traditional carriers.

Description

Technical Field

[0001] This invention relates to the field of three-way catalytic converters, and more particularly to a support structure for a three-way catalytic converter. Background Technology

[0002] As a core component of automotive exhaust purification systems, the three-way catalytic converter's carrier structure design directly determines the exhaust purification efficiency, system back pressure, and service life.

[0003] Currently, most mainstream three-way catalytic converter carriers on the market adopt a homogeneous honeycomb structure. This type of carrier uses a catalytic coating loaded with noble metals such as Pt, Pd, and Rh on a substrate to utilize the redox properties of these noble metals to remove carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) from the exhaust gas. x Purification treatment.

[0004] However, traditional carriers employ a uniform pore size and density design across the entire surface area, which cannot adapt to the velocity distribution characteristics of exhaust gas in the carrier cross section, resulting in unreasonable flow resistance. Summary of the Invention

[0005] To address the problem of unreasonable flow resistance in traditional carriers, this invention provides a carrier structure for a three-way catalytic converter.

[0006] This invention provides a support structure for a three-way catalytic converter, employing the following technical solution: A support structure for a three-way catalytic converter includes a support body, wherein the support body has an axial gradient structure with decreasing pore size gradient and increasing pore density gradient along the axial airflow direction, and a radial gradient structure with increasing pore size gradient and decreasing pore density gradient along the radial direction away from the center.

[0007] By adopting the above technical solution and designing an axial gradient structure, the coarse-hole inlet can significantly reduce the initial resistance to airflow and make the airflow unfold more smoothly. The airflow velocity is relatively slow, so it can react and contact the carrier normally and fully. When the airflow passes through the fine-hole, the airflow velocity increases, which allows the airflow to leave the carrier quickly and carry away heat, making it less likely for heat to accumulate at the tail of the carrier.

[0008] Optionally, the carrier body includes an inner ring portion and an outer ring portion located outside the inner ring portion; the inner ring portion is divided into multiple channel regions along the airflow direction, and the axial gradient structure includes channels located in each of the channel regions, wherein the channel diameter decreases gradually with respect to the channel region, and the channel density increases gradually with respect to the channel region.

[0009] Optionally, the radial gradient structure includes an inner channel located in the inner ring and an outer channel located in the outer ring; the diameter of the inner channel is smaller than the diameter of the outer channel; and the pore density of the inner channel is greater than the pore density of the outer channel.

[0010] Optionally, the surface of the carrier body is coated with a catalytic coating containing Pt, Pd, and Rh noble metals; the Rh noble metal content of the catalytic coating on the inlet side of the carrier body is higher than that on the outlet side of the carrier body, and the Pt and Pd noble metal content of the catalytic coating on the inlet side is lower than that on the outlet side of the carrier body. The thickness of the catalytic coating in the inner pores is less than the thickness of the catalytic coating in the outer pores.

[0011] By adopting the above technical solution, Rh noble metal can reduce nitrogen oxides NOx, while Pt and Pd noble metals can oxidize carbon monoxide CO and hydrocarbons CH. When the exhaust gas passes through the inlet side of the carrier body, it can be quickly ignited, thereby enhancing the reduction of nitrogen oxides NOx. When the exhaust gas passes through the outlet side, carbon monoxide CO and hydrocarbons CH can be deeply oxidized. Meanwhile, the inner channel has a thin catalytic coating with a low precious metal content, which can prevent local overheating and sintering when the exhaust gas passes through; the outer channel has a thick catalytic coating with a high precious metal content, which can improve the utilization rate.

[0012] Optionally, the surface of the carrier body is densely covered with pores, and the pore diameter gradually increases in the direction away from the surface of the carrier body; the catalytic coating is formed by coating layer by layer, consisting of an anchoring layer that penetrates into the pores, a catalytic layer for catalysis, and an intermediate auxiliary layer that binds the anchoring layer and the catalytic layer.

[0013] By adopting the above technical solution and designing a porous microstructure on the wall, the catalytic coating can be fixedly connected to the wall of the carrier body through the anchoring layer, ensuring the structural strength of the catalytic coating and improving the adhesion of the catalytic coating.

[0014] Optionally, the intermediate additive layer array has through holes communicating with the anchoring layer, and the catalyst layer is coated on the outside of the intermediate additive layer and connected to the anchoring layer through the through holes.

[0015] By adopting the above technical solution, and by designing the intermediate auxiliary layer as a connected porous network structure, the catalyst layer can be directly connected to the anchoring layer. The Pt / Pd / Rh noble metal particles in the catalyst layer can be anchored through the oxygen vacancies of the intermediate auxiliary layer, thus avoiding agglomeration.

[0016] Optionally, the inner ring is formed of a plurality of carrier sheet units and an adhesive layer connecting adjacent carrier sheet units.

[0017] By adopting the above technical solution, multiple carrier sheet units are laminated to form the inner ring, which is beneficial for the processing of microstructures in a single carrier sheet unit. After the processing of a single carrier sheet unit is completed, the entire inner ring carrier is formed.

[0018] Optionally, each of the channels on the carrier sheet unit has an inclined angle with the axis, and the inclined directions of the channels on adjacent carrier sheet units are opposite.

[0019] By adopting the above technical solution, when the exhaust gas passes through the channel, the serrated zigzag channel can increase the contact area between the catalytic coating and the airflow, so that the exhaust gas molecules in the airflow can fully react.

[0020] Optionally, the included angle of inclination of the channels in the inner ring increases gradually in units of channel regions; the channels in adjacent channel regions are aligned.

[0021] Optionally, the inner ring is slidably mounted on the outer ring, and the carrier body further includes ceramic springs symmetrically arranged at both ends of the inner ring and a sealing ring for fixing the ceramic springs to the outer ring; when the airflow passes through the carrier body, the inner ring moves toward the air outlet side of the carrier body and resets its vibration when the airflow stops; Both the outer wall of the inner ring and the inner wall of the outer ring are spaced apart by protruding rings. When cooled at low temperature, the protruding rings of the two separate from each other, and when expanded at high temperature, the protruding rings of the two engage and fix each other.

[0022] By adopting the above technical solution, the ceramic spring drives the inner ring to move back and forth during the alternation of hot and cold. During the movement, the convex rings collide with each other, causing the inner ring to vibrate slightly, thereby shaking off and removing the carbon deposits on the carrier body.

[0023] In summary, this application includes at least one of the following beneficial technical effects: The coarse-pore inlet can significantly reduce the initial resistance to airflow and allow the airflow to spread more smoothly. The airflow velocity is slower, so it can react and contact with the carrier normally and fully. When the airflow passes through the fine-pore inlet, the airflow velocity increases, which allows the airflow to leave the carrier quickly and can carry away heat, so that heat is not easy to accumulate at the tail of the carrier. By designing a porous microstructure on the wall, the catalytic coating can be fixedly connected to the wall of the carrier body through an anchoring layer, ensuring the structural strength of the catalytic coating and improving its adhesion. When the temperature changes, the ceramic spring drives the inner ring to move back and forth. During the movement, the convex rings collide with each other, causing the inner ring to vibrate slightly, thereby shaking off and removing the carbon deposits on the carrier body. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the support structure of a three-way catalytic converter according to an embodiment of the present invention; Figure 2 This is an exploded view of the catalytic coating according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of the carrier body according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the inner ring portion according to an embodiment of the present invention.

[0025] The parts referred to by the numbers in the above figures are as follows: 1. Carrier body; 2. Catalytic coating; 21. Anchoring layer; 22. Intermediate additive layer; 23. Catalytic layer; 24. Through hole; 3. Pore; 4. Inner ring; 41. Carrier sheet unit; 42. Adhesive layer; 5. Outer ring; 6. Ceramic spring; 7. Sealing ring; 8. Inner channel; 9. Outer channel. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0027] This application discloses a support structure for a three-way catalytic converter.

[0028] Reference Figure 1 A three-way catalytic converter carrier structure includes a carrier body 1, which is used to adsorb and treat automobile exhaust gas. The carrier body 1 is cylindrical and made of metal, and its surface is coated with a catalytic coating 2, in which precious metals such as Pt, Pd, and Rh are loaded as catalysts.

[0029] The carrier body 1 has through-holes along the axial direction, and the cross-section of the carrier body 1 is densely covered with holes to form a honeycomb-like pore structure. The catalytic coating 2 is mainly coated on the pore walls, and the catalytic coating 2 treats the exhaust gas as it passes through the pores.

[0030] Reference Figure 2 To ensure that the catalytic coating 2 adheres firmly to the surface of the carrier body 1, the surface of the carrier body 1 has a wall microstructure to enhance the bonding strength of the catalytic coating 2. The wall microstructure includes pores 3 densely distributed on the surface of the carrier body 1, the pore diameter of the pores 3 gradually increasing in the direction away from the surface of the carrier body 1, and is in the shape of an inverted cone.

[0031] Meanwhile, the catalytic coating 2 includes an anchoring layer 21, an intermediate auxiliary agent layer 22, and a catalytic layer 23.

[0032] Anchoring layer 21 engages with and interlocks within pores 3. Intermediate additive layer 22 is located outside anchoring layer 21 and coated on the surface of carrier body 1. Intermediate additive layer 22 has a continuous porous network structure, its array having through holes 24 communicating with anchoring layer 21. Catalytic layer 23 is coated on the outside of intermediate additive layer 22, and catalytic layer 23 is connected to anchoring layer 21 through through holes 24 of intermediate additive layer 22. Intermediate additive layer 22 serves as a bonding layer connecting anchoring layer 21 and catalytic layer 23, and catalytic layer 23 is used for treating exhaust gas.

[0033] The anchoring layer 21 is mainly composed of γ-Al₂O₃, aluminum sol, and silica sol. The intermediate additive layer 22 is mainly composed of CeO₂-ZrO₂ solid solution and a small amount of La₂O₃ / Nd₂O₃, with La₂O₃ / Nd₂O₃ acting as a stabilizer. The catalyst layer 23 is mainly composed of Pt / Pd / Rh noble metal nanoparticles and a thin γ-Al₂O₃ coating, with the Pt / Pd / Rh noble metal nanoparticles used for the oxidation-reduction of exhaust gas molecules.

[0034] The coating slurry of the anchoring layer 21 penetrates into the pores 3 and, after curing, forms a micro-mortise and tenon structure, mechanically interlocking with the wall of the carrier body 1. Simultaneously, aluminum sol and silica sol form Si-O-Al covalent bonds at the interface, achieving chemical anchoring. The intermediate additive layer 22 covers the surface of the anchoring layer 21, forming a continuous porous network that does not clog the through-holes 24. The catalyst layer 23 is enriched on the surface of the intermediate additive layer 22 and at the entrance of the through-holes 24, facilitating contact with exhaust gas molecules. Furthermore, Pt / Pd / Rh noble metal particles can be anchored through the oxygen vacancies in the intermediate additive layer 22, preventing agglomeration.

[0035] In this embodiment, the Rh noble metal content of the catalytic coating 2 on the inlet side of the carrier body 1 is higher than that on the outlet side, and the Pt and Pd noble metal contents on the inlet side are lower than those on the outlet side.

[0036] When the exhaust gas flows through the carrier body 1, under the catalytic action of the Rh noble metal on the intake side, the nitrogen oxides NOx in the exhaust gas are reduced to nitrogen N2 and oxygen O2. At the same time, some of the nitrogen oxides NOx will also react directly with carbon monoxide CO and hydrocarbons CH in the exhaust gas to generate nitrogen N2, carbon dioxide CO2 and water.

[0037] When the exhaust gas flows to the outlet side after the reaction, under the catalytic action of Pt and Pd noble metals, carbon monoxide (CO) and hydrocarbons (CH) in the exhaust gas can be oxidized to carbon dioxide (CO2). During this process, the oxygen produced by the reaction on the inlet side can be supplied to the outlet side.

[0038] Based on the above distribution of precious metals, the exhaust gas can be quickly ignited when it passes through the intake side of the carrier body 1, thereby enhancing the reduction of nitrogen oxides (NOx). Furthermore, carbon monoxide (CO) and hydrocarbons (CH) can be deeply oxidized when the exhaust gas passes through the outlet side.

[0039] Reference Figure 2 and Figure 3 The carrier body 1 includes an inner ring portion 4 and an outer ring portion 5. The inner ring portion 4 is cylindrical, and the outer ring portion 5 is cylindrical. The outer ring portion 5 is fitted over the outer side of the inner ring portion 4. Here, the channel on the outer ring portion 5 is defined as the outer channel 9, and the channel on the inner ring portion 4 is defined as the inner channel 8.

[0040] In this embodiment, the carrier body 1 employs different pore structures from its center to its edge, i.e., it has a radial gradient structure. Specifically, as the pores move away from the center of the carrier body 1, the pore diameter gradient increases while the pore density gradient decreases. That is, the pore diameter of the inner pores 8 is smaller than that of the outer pores 9, and the pore density of the inner pores 8 is greater than that of the outer pores 9. Furthermore, the thickness of the catalytic coating 2 in the inner pores 8 is less than that in the outer pores 9.

[0041] High-density, small-sized inner channels 8 are arranged in the inner ring portion 4 of the carrier body 1, while low-density, large-sized outer channels 9 are arranged in the outer ring portion 5. This structure can match the exhaust gas velocity distribution, allowing high flow areas to correspond to high reaction areas and low flow areas to correspond to low-resistance channels. Furthermore, the outer channels 9 of the outer ring portion 5 provide a low-resistance path for the airflow, compensating for the higher resistance of the inner ring portion 4.

[0042] Meanwhile, because the catalytic coating 2 of the inner channel 8 is thin and has a low precious metal content, local overheating and sintering can be avoided when the exhaust gas passes through. Furthermore, because the catalytic coating 2 of the outer channel 9 is thick and has a high precious metal content, its utilization rate can be improved.

[0043] In this embodiment, the carrier body 1 has an axial gradient structure along the axial airflow direction, in which the pore diameter gradient decreases and the pore density gradient increases. Specifically, the pore diameter at the front end of the carrier body 1 is larger than the pore diameter at the rear end of the carrier body 1, and the pore density at the front end of the carrier body 1 is smaller than the pore density at the rear end of the carrier body 1.

[0044] Furthermore, the inner ring 4 is divided into multiple channel regions along the airflow direction. The orifice diameter of the inner channel 8 decreases progressively with respect to each channel region; that is, the orifice diameter remains constant within a single channel region, while there is a gradient change in the orifice diameter between adjacent channel regions. Additionally, the orifice density of the inner channel 8 increases progressively with respect to each channel region.

[0045] The channel structure of the outer ring 5 is the same as that of the inner ring 4, and will not be described in detail here.

[0046] Reference Figure 3 and Figure 4 Furthermore, the inner ring portion 4 includes multiple carrier sheet units 41 and an adhesive layer 42. The multiple carrier sheet units 41 are stacked, and adjacent carrier sheet units 41 are connected by the adhesive layer 42.

[0047] In this embodiment, the inner channels 8 on each carrier sheet unit 41 are inclined, and the axis of the inner channel 8 has an inclined angle with the axis of the carrier sheet unit 41. Furthermore, when multiple carrier sheet units 41 are bonded together, the inclination directions of the inner channels 8 of adjacent carrier sheet units 41 are opposite, so that the channels of the inner ring portion 4 present a zigzag shape.

[0048] Meanwhile, the inclination angles of the inner channels 8 in different channel regions are different. The inclination angles of the inner channels 8 increase gradually along the airflow direction. Furthermore, the channels in adjacent channel regions are directly opposite each other. That is, the inclination angles of the inner channels 8 on the carrier sheet unit 41 of a single channel region are all the same, and only the inclination directions of the inner channels 8 on adjacent carrier sheet units 41 are opposite. However, the inclination angles of the inner channels 8 on the carrier sheet units 41 in adjacent channel regions are different.

[0049] Reference Figure 3 Furthermore, in this embodiment, the inner ring portion 4 is slidably mounted on the outer ring portion 5, and the carrier body 1 also includes a ceramic spring 6 and a sealing ring 7. The ceramic spring 6 is symmetrically arranged at both ends of the inner ring portion 4, and the sealing ring 7 abuts against the ceramic spring 6 and is fixedly connected to the outer ring portion 5, thereby fixing the ceramic spring 6 to the outer ring portion 5. At the same time, the outer wall of the inner ring portion 4 and the inner wall of the outer ring portion 5 are both provided with convex rings at intervals. The convex rings are circular and their size is on the micrometer scale. Moreover, the convex rings separate from each other when cooled at low temperature and engage and fix each other when expanded at high temperature.

[0050] When the exhaust gas passes through the carrier body 1 and impacts the inner ring 4, since the carrier body 1 is still in a low-temperature cooling state, the inner ring 4 can move along the flow direction of the exhaust gas and compress the ceramic spring 6 on the exhaust side of the carrier body 1. When the temperature of the carrier body 1 rises, the convex ring on the outer wall of the inner ring 4 and the convex ring on the inner wall of the outer ring 5 expand due to heat and mesh with each other to fix them, thereby locking the inner ring 4 and the outer ring 5. During this process, the ceramic spring 6 can relieve the force on the inner ring 4.

[0051] After the carrier body 1 cools down again, the inner ring 4 is reset. During this process, the inner ring 4 moves back and forth, and the convex rings collide with each other, causing the inner ring 4 to vibrate slightly, thereby shaking off and removing the carbon deposits on the carrier body 1.

[0052] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A support structure for a three-way catalytic converter, comprising a support body (1), characterized in that, The carrier body (1) has an axial gradient structure with decreasing pore diameter gradient and increasing pore density gradient along the axial airflow direction, and the carrier body (1) has a radial gradient structure with increasing pore diameter gradient and decreasing pore density gradient along the radial direction away from the center.

2. The support structure for a three-way catalytic converter according to claim 1, characterized in that, The carrier body (1) includes an inner ring (4) and an outer ring (5) located outside the inner ring (4); the inner ring (4) is divided into multiple channel regions along the direction of airflow, and the axial gradient structure includes channels located in each channel region. The channel diameter decreases gradually in units of channel regions, and the channel density increases gradually in units of channel regions.

3. The support structure for a three-way catalytic converter according to claim 2, characterized in that, The radial gradient structure includes an inner channel (8) located in the inner ring (4) and an outer channel (9) located in the outer ring (5); the diameter of the inner channel (8) is smaller than the diameter of the outer channel (9); the pore density of the inner channel (8) is greater than the pore density of the outer channel (9).

4. The support structure for a three-way catalytic converter according to claim 3, characterized in that, The surface of the carrier body (1) is coated with a catalytic coating (2) containing Pt, Pd and Rh noble metals; the Rh noble metal content of the catalytic coating (2) on the inlet side of the carrier body (1) is higher than that on the outlet side of the carrier body (1), and the Pt and Pd noble metal content of the catalytic coating (2) on the inlet side is lower than that on the outlet side of the carrier body (1). The thickness of the catalytic coating (2) of the inner channel (8) is less than the thickness of the catalytic coating (2) of the outer channel (9).

5. The support structure for a three-way catalytic converter according to claim 4, characterized in that, The surface of the carrier body (1) is densely covered with pores (3), and the pore size of the pores (3) gradually increases in the direction away from the surface of the carrier body (1); the catalytic coating (2) is formed by coating layer by layer from the anchoring layer (21) that penetrates into the pores (3), the catalytic layer (23) for catalysis, and the intermediate auxiliary agent layer (22) that binds the anchoring layer (21) and the catalytic layer (23).

6. The support structure for a three-way catalytic converter according to claim 5, characterized in that, The intermediate additive layer (22) array has through holes (24) communicating with the anchoring layer (21), and the catalyst layer (23) is coated on the outside of the intermediate additive layer (22) and connected to the anchoring layer (21) through the through holes (24).

7. The support structure for a three-way catalytic converter according to claim 2, characterized in that, The inner ring (4) is formed by a plurality of carrier sheet units (41) and an adhesive layer (42) connecting adjacent carrier sheet units (41).

8. The support structure for a three-way catalytic converter according to claim 7, characterized in that, Each of the carrier sheet units (41) has an inclined angle between the channel and the axis, and the channels on adjacent carrier sheet units (41) have opposite inclination directions.

9. The support structure for a three-way catalytic converter according to claim 8, characterized in that, The included angle of inclination of the channels in the inner ring (4) increases gradually in units of channel regions; the channels in adjacent channel regions are directly opposite each other.

10. The support structure for a three-way catalytic converter according to claim 2, characterized in that, The inner ring (4) is slidably mounted on the outer ring (5). The carrier body (1) also includes ceramic springs (6) symmetrically arranged at both ends of the inner ring (4) and a sealing ring (7) that fixes the ceramic springs (6) to the outer ring (5). When the airflow passes through the carrier body (1), the inner ring (4) moves toward the air outlet side of the carrier body (1) and resets its vibration when the airflow stops. The outer wall of the inner ring (4) and the inner wall of the outer ring (5) are both provided with convex rings at intervals. When cooled at low temperature, the convex rings of the two separate from each other, and when expanded at high temperature, the convex rings of the two engage and fix each other.

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