Ceramic unit, honeycomb ceramic carrier and preparation method therefor, and exhaust gas catalytic core

Abstract

A ceramic unit. Two ends of the ceramic unit are respectively an air intake end (01) and an air output end (02). The ceramic unit is provided with a plurality of compartments, which are separated by partition walls and extend in the longitudinal direction of the ceramic unit. The compartments comprise first compartments (11) and second compartments (12) that are alternately arranged in a cross section in the ceramic unit, wherein the sides of the first compartments (11) at the air intake end (01) are open, and the sides of the first compartments (11) at the air output end (02) are blocked; the sides of the second compartments (12) at the air intake end (01) are blocked, and the sides of the second compartments (12) at the air output end (02) are open; each partition wall is provided with a plurality of air holes for connecting the first compartments (11) to the second compartments (12); and the average pore diameter of the openings of the air holes at the side of the first compartments (11) is Di, and the average pore diameter of the openings of the air holes at the side of the second compartments (12) is Do, Di being smaller than Do. The ceramic unit can improve the waste gas purification efficiency. Further provided are a honeycomb ceramic carrier provided with the ceramic unit, and a preparation method therefor, and an exhaust gas catalytic core provided with the ceramic unit.

Description

Ceramic unit, honeycomb ceramic carrier and preparation method thereof, exhaust gas catalytic core Technical Field

[0001] The present invention relates to the field of honeycomb ceramic catalysis, and in particular to a ceramic unit body, a honeycomb ceramic carrier and a preparation method thereof, and an exhaust gas catalytic core. Background Art

[0002] Diesel vehicle exhaust pollutants primarily include carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM, also known as PM, composed of dry soot, liquid hydrocarbons, and a small amount of sulfate). Typically, an exhaust gas purification system consists of a soot oxidation catalyst (DOC), a diesel soot filter (DPF), a reductant injector, and a selective catalytic reduction (SCR) device, installed in sequence on the exhaust pipe that discharges the exhaust gas. The exhaust gas generated by the engine is sequentially applied to the DOC, the DPF, and the SCR device, removing harmful substances contained in the exhaust gas. The DOC oxidizes the carbon monoxide and hydrocarbons contained in the exhaust gas into carbon dioxide, while the filter collects and selectively catalytically reduces particulate matter (PM) contained in the exhaust gas. The device uses a reductant or nitrogen oxide injected from the reductant injector to adsorb nitrogen oxides contained in the exhaust gas. The DPF is typically coated with a catalyst that oxidizes accumulated soot, carbon monoxide, and hydrocarbons. If the catalyst loading level in the filter is high enough, the functionality of an upstream soot oxidation catalyst can be integrated into the DPF.

[0003] Therefore, how to improve the conversion rate of exhaust gas and the capture efficiency of particles in waste need to be solved urgently. Summary of the Invention

[0004] The purpose of the present invention is to provide a ceramic unit body, a honeycomb ceramic carrier and its preparation method, and an exhaust gas catalytic core, which can be coated with a soot oxidation catalyst and a DPF oxidation catalyst at the same time to improve the conversion rate of exhaust gas and the capture efficiency of particles in exhaust gas.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A ceramic unit body, wherein the two ends of the ceramic unit body in the longitudinal direction are respectively an air inlet end and an air outlet end, and the ceramic unit body has a plurality of compartments separated by partition walls and extending in the longitudinal direction of the ceramic unit body;

[0007] The compartments include first compartments and second compartments alternately arranged in a cross section of the ceramic unit body, the first compartments being open on one side of the air inlet end and blocked on one side of the air outlet end, and the second compartments being blocked on one side of the air inlet end and open on one side of the air outlet end;

[0008] The partition wall is provided with a plurality of pores connecting the first compartment and the second compartment; the average pore diameter of the pores opening on the first compartment side is Di, the average pore diameter of the pores opening on the second compartment side is Do, and Di <Do。

[0009] In some embodiments of the present invention, at least one of the air holes has at least two openings on the first compartment side, and the aperture of at least one of the openings on the first compartment side is smaller than the aperture of the air hole on the second compartment side.

[0010] And / or, in at least one of the pores, the number of its openings on the second compartment side is at least two, and the aperture of at least one of the openings on the second compartment side is larger than the aperture of the opening of the pore on the first compartment side.

[0011] In some embodiments of the present invention, the average pore diameter Di∈[8,20] of the pores on one side of the first compartment is in micrometers, preferably, Di∈[12,20], in micrometers;

[0012] And / or, the average pore diameter of the opening of the pore on one side of the second compartment is Do∈[11,23], in micrometers, preferably, Do∈[15,23], in micrometers.

[0013] In some embodiments of the present invention, the cross-sections of the first compartment and the second compartment are both square or rectangular;

[0014] And / or, the first compartments and the second compartments are alternately arranged in a checkerboard pattern in a cross section of the ceramic unit body.

[0015] In some embodiments of the present invention, the thickness of the partition wall is 75 to 250 μm, preferably 125 to 200 μm;

[0016] And / or, the cross-sectional area of ​​the first compartment is greater than the cross-sectional area of ​​the second compartment, or the cross-sectional area of ​​the first compartment is smaller than the cross-sectional area of ​​the second compartment, or the cross-sectional area of ​​the first compartment is equal to the cross-sectional area of ​​the second compartment.

[0017] In some embodiments of the present invention, the distribution density of the pores on the partition wall, i.e., the porosity, is 35-55%;

[0018] And / or, the pore density of the compartment in the ceramic unit body is 200-500 meshes.

[0019] In order to achieve the above object, the present invention also provides the following technical solutions:

[0020] A method for preparing the above-mentioned ceramic unit body, the method comprising the following steps:

[0021] A1, dry-mixing silicon carbide powder, silicon powder, alkaline earth metal carbonate, metal oxide powder, additives, a binder, and a pore-forming agent to obtain a dry mix;

[0022] A2, wet mixing the dry mix obtained in step A1 with water and a lubricant to obtain a wet mix;

[0023] A3, kneading, mixing, extruding, drying, plugging, degreasing, and sintering the wet mixture obtained in step A2 to obtain the ceramic unit body;

[0024] The sintering in step A3 includes oxygen-free sintering and oxidation sintering performed sequentially. The oxidation sintering process is as follows: exposing the air inlet end of the green body that has completed oxygen-free sintering to air, and performing negative pressure extraction on the air outlet end of the green body, so that air passes through the first compartment, the pores, the second compartment, and then leaves the green body from the air outlet end in sequence, thereby forming the pores, so that the average pore diameter Do of the opening of the pore on the side of the second compartment is larger than the average pore diameter Di of the opening on the side of the first compartment;

[0025] Preferably, the dry mixing is performed using a plowshare high-speed mixer, the dry mixing time is 10 to 30 minutes, and the dry mixing speed is 50 to 200 rpm;

[0026] Preferably, the wet mixing time is 1 to 20 minutes, and the wet mixing speed is 50 to 200 rpm;

[0027] Preferably, a biaxial kneader is used for kneading, and the kneading time is 30 to 180 minutes.

[0028] In some embodiments of the present invention, in step A1, the negative pressure used in the negative pressure extraction is (-0.05) to (-0.02) MPa.

[0029] In some embodiments of the present invention, in step A1, the silicon carbide powder includes a first silicon carbide powder having an average particle size of 20 to 30 μm and a second silicon carbide powder having an average particle size of 3 to 8 μm.

[0030] In some embodiments of the present invention, in step A1, based on the total amount of the silicon carbide powder being 100 wt.%, the first silicon carbide powder accounts for 70 to 95 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 5 to 30 wt.% of the total silicon carbide powder.

[0031] In some embodiments of the present invention, in step A1, based on the mass of the total raw materials as 100 wt.%, the proportion of the silicon carbide powder is 50-75 wt.%, preferably 50-65 wt.%, the proportion of the silicon powder is 15-25 wt.%, preferably 15-20 wt.%, the proportion of the alkaline earth metal carbonate is 1-2 wt.%, the proportion of the metal oxide powder is 0.2-1 wt.%, the proportion of the auxiliary agent is 0.5-1.5 wt.%, the proportion of the binder is 6-15 wt.%, the proportion of the pore-forming agent is 3-18 wt.%, and the proportion of the lubricant is 5-11 wt.%.

[0032] In some embodiments of the present invention, the average particle size of the silicon powder is 3-10 μm, the average particle size of the alkaline earth metal carbonate is 2-6 μm, the average particle size of the metal oxide is 3-8 μm, and the average particle size of the pore-forming agent is 8-40 μm.

[0033] In some embodiments of the present invention, the alkaline earth metal carbonate is selected from at least one of magnesium carbonate, strontium carbonate, barium carbonate, and calcium carbonate.

[0034] In some embodiments of the present invention, the metal oxide is aluminum oxide.

[0035] In some embodiments of the present invention, the auxiliary agent is selected from at least one of bentonite and kaolin.

[0036] In some embodiments of the present invention, the binder is selected from at least one of organic alcohols, potassium laurate, modified cellulose, polyethylene oxide, and polyvinyl pyrrolidone.

[0037] In some embodiments of the present invention, the pore-forming agent is selected from at least one of walnut powder, graphite, benzoic acid, starch, ammonium bicarbonate, ammonium chloride, polymethyl methacrylate, and expanded microspheres.

[0038] In some embodiments of the present invention, the lubricant is glycerol.

[0039] In order to achieve the above object, the present invention also provides the following technical solutions:

[0040] A honeycomb ceramic carrier is composed of the above-mentioned ceramic unit bodies or ceramic unit bodies produced by the above-mentioned method. Each of the ceramic unit bodies is distributed and connected in the cross section of the honeycomb ceramic carrier, and the longitudinal direction of the ceramic unit bodies is the same as the longitudinal direction of the honeycomb ceramic carrier.

[0041] In some embodiments of the present invention, the thermal conductivity of the honeycomb ceramic support is 5 to 30 W / m·K, preferably 10 to 30 W / m·K, and more preferably 13 to 25 W / m·K.

[0042] In some embodiments of the present invention, the honeycomb ceramic carrier is a cylinder or a polygonal prism.

[0043] In order to achieve the above object, the present invention also provides the following technical solutions:

[0044] A method for preparing the above-mentioned honeycomb ceramic carrier, characterized in that the method comprises the following steps:

[0045] B1, providing the above-mentioned ceramic unit body, or providing a ceramic unit body produced by the above-mentioned method;

[0046] B2, the ceramic unit bodies are sequentially subjected to splicing, grinding, and skin grafting processes to obtain the honeycomb ceramic carrier.

[0047] In order to achieve the above object, the present invention also provides the following technical solutions:

[0048] An exhaust gas catalytic core, comprising:

[0049] The honeycomb ceramic carrier mentioned above or the honeycomb ceramic carrier prepared by the above method;

[0050] A first catalyst is applied to the inner wall surface of the first compartment of the honeycomb ceramic support;

[0051] The second catalyst is applied to the inner wall surface of the second compartment of the honeycomb ceramic support.

[0052] In some embodiments of the present invention, the exhaust gas catalytic core is used to catalyze exhaust gas containing soot particles, the first catalyst is used to promote oxidation of the soot particles, and the second catalyst is used to catalyze conversion of carbon monoxide, hydrocarbons, and nitrogen oxides.

[0053] Further areas of applicability will become apparent from the description provided in this disclosure.

[0054] The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0055] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0056] The present invention provides a wall-flow honeycomb ceramic carrier that can simultaneously load a DOC oxidation catalyst (i.e., a soot oxidation catalyst) and a DPF oxidation catalyst. The regeneration temperature equilibrium point after loading is lower, and the capture efficiency and exhaust gas conversion rate are similar to those of a DOC+DPF exhaust gas treatment system, while saving the volume and cost of a diesel vehicle exhaust system. Specifically, by controlling the pore density of the carrier and increasing the opening area on the outlet side of the carrier, the contact area between the catalyst and the reaction gas is increased, and both DOC and DPF catalysts can be coated at the same time. The exhaust gas conversion rate and particle capture efficiency are similar to those of a DOC+DPF exhaust system, saving the volume and cost of a diesel vehicle waste exhaust system. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some implementation plans of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0058] FIG1 is a schematic diagram of the appearance of a honeycomb ceramic support in which the cross-sectional area of ​​the first compartment is larger than the cross-sectional area of ​​the second compartment, provided by the first embodiment of the present invention;

[0059] FIG2 is a schematic structural diagram of the honeycomb ceramic substrate in FIG1 at a first viewing angle;

[0060] FIG3 is a partial enlarged schematic diagram of area A in FIG2 ;

[0061] 4 is a schematic structural diagram of a honeycomb ceramic support in which the cross-sectional area of ​​the first compartment is equal to the cross-sectional area of ​​the second compartment provided by the second embodiment of the present invention at a second viewing angle;

[0062] FIG5 is a partial enlarged schematic diagram of area B in FIG4 ;

[0063] FIG6 is a schematic cross-sectional structure diagram of the honeycomb ceramic substrate in FIG1 taken along its longitudinal direction;

[0064] FIG7 is a schematic cross-sectional view of the air holes on a portion of the partition wall in FIG6 ;

[0065] FIG8 is a flow chart of a method for preparing a ceramic unit body according to a third embodiment of the present invention;

[0066] FIG9 is a flow chart of a method for preparing a honeycomb ceramic substrate according to a fourth embodiment of the present invention;

[0067] FIG10 is a SEM morphology of the pores of the honeycomb ceramic support provided in the fifth embodiment of the present invention at the aperture sampling area on one side of the first compartment;

[0068] FIG11 is a SEM morphology of the pores of the honeycomb ceramic support provided in the fifth embodiment of the present invention at the aperture sampling area on one side of the second compartment;

[0069] FIG12 is a partially enlarged SEM morphology of the pores of the honeycomb ceramic support provided by the fifth embodiment of the present invention at the aperture sampling area on one side of the first compartment;

[0070] FIG13 is a partially enlarged SEM morphology of the pores of the honeycomb ceramic support provided by the fifth embodiment of the present invention at the aperture sampling area on one side of the first compartment;

[0071] Figure 14 is a SEM morphology of the partition wall of the honeycomb ceramic support provided by the fifth embodiment of the present invention. The main reference numerals in the drawings of the present invention are as follows: 01 - air inlet side; 02 - air outlet side; 11 - first compartment; 12 - second compartment. DETAILED DESCRIPTION

[0072] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0073] Any specific numerical value disclosed herein (including the endpoints of a numerical range) is not limited to the exact value of the numerical value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Moreover, for a disclosed numerical range, any combination of the endpoints of the range, between the endpoints and the specific points in the range, and between the specific points can be used to generate one or more new numerical ranges, and these new numerical ranges should also be considered to be specifically disclosed herein.

[0074] The terms used in this disclosure are intended only to describe specific exemplary embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used in this disclosure may be intended to also include plural forms. The terms "comprise", "include", "contain", and "have" are inclusive and therefore illustrate the presence of the features, elements, compositions, steps, integers, operations, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or their collections. Although the open-ended term "comprising" should be understood as a non-limiting term for describing and claiming the various embodiments described in this disclosure, in some aspects, the term may alternatively be understood as a more restrictive and limited term, such as "consisting of" or "substantially consisting of". Thus, for any given embodiment of a narration composition, material, component, element, feature, integer, operation, and / or process step, the disclosure also specifically includes an embodiment consisting of or substantially consisting of such a composition, material, component, element, feature, integer, operation, and / or process step. In the case of "consisting of," alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations and / or process steps, while in the case of "consisting essentially of," any additional compositions, materials, components, elements, features, integers, operations and / or process steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, features, integers, operations and / or process steps that do not materially affect the basic and novel characteristics may be included in such embodiments.

[0075] Any method steps, processes, and operations described in this disclosure are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless expressly identified as a certain order of performance. It is also to be understood that additional or alternative steps may be used unless otherwise stated.

[0076] In the present invention, except for the contents explicitly described, any matters or issues not mentioned are directly applicable to those known in the art without any changes. Moreover, any embodiment described in this disclosure can be freely combined with one or more other embodiments described in this disclosure, and the technical solutions or technical ideas formed thereby are considered part of the original disclosure or original description of the present invention, and should not be regarded as new content not disclosed or anticipated in this disclosure, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0077] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition herein shall prevail.

[0078] Unless otherwise stated, when % is mentioned herein, it means wt.%.

[0079] It is worth noting that the DOC described in the specification of the present invention refers to Diesel Oxidation Catalyst, that is, diesel oxidation catalyst; DPF refers to Diesel Particulate Filter, that is, diesel particulate filter.

[0080] It is worth noting that the soot particles described in this specification, also known as PM, are composed of dry soot, liquid hydrocarbons, and a small amount of sulfate. Soot particles can be considered as products produced during the incomplete combustion of diesel. The ceramic unit, honeycomb ceramic carrier, and exhaust catalytic core provided by the present invention can promote the efficiency of passive regeneration of soot particles. "Passive regeneration" refers to "removing particulate matter from the particle trap by reducing the activation energy of the soot oxidation reaction, without the need for external energy or intervention, and using only the heat generated by the exhaust gas to complete the reaction."

[0081] In the context of the present disclosure, Di represents the average pore diameter of the openings of the pores on the first compartment side, and Do represents the average pore diameter of the openings of the pores on the second compartment side.

[0082] In the context of this disclosure, cell density refers to the number of cells per square inch of area, in mesh; wherein the cells include both first and second compartments.

[0083] It is worth noting that, in some embodiments of the present invention, the above-mentioned exhaust catalytic core can be used for catalytic purification of exhaust gas or waste gas, and more specifically, can be used for exhaust gas or waste gas generated by incomplete combustion of diesel.

[0084] First aspect

[0085] Referring to Figures 1 to 7, a ceramic unit body, referring to Figure 6, wherein the two ends of the ceramic unit body in the longitudinal direction are an air inlet end 01 and an air outlet end 02, respectively, and the ceramic unit body has a plurality of compartments separated by partition walls and extending along the longitudinal direction of the ceramic unit body; referring to Figures 2 to 5, the compartments include a first compartment 11 and a second compartment 12 alternately arranged in the cross section of the ceramic unit body; referring to Figures 6 and 7, the first compartment 11 is open on one side of the air inlet end 01 and blocked on one side of the air outlet end 02, and the second compartment 12 is blocked on one side of the air inlet end 01 and open on one side of the air outlet end 02; wherein, referring to Figure 7, the average pore size of the pores opening on one side of the first compartment 11 is Di, the average pore size of the pores opening on one side of the second compartment 12 is Do, and Di <Do。

[0086] It is worth noting that, since the present invention also provides a honeycomb ceramic carrier composed of a plurality of the above-mentioned ceramic unit bodies, the present invention specification may refer to the structural schematic diagram of the above-mentioned honeycomb ceramic carrier when introducing the structure of the above-mentioned ceramic unit bodies.

[0087] Specifically, the ceramic unit body provided by the present invention has a unique structural design for the partition wall between the two compartments inside it: referring to Figures 6 and 7, the average pore size Di of the pores opening on the side of the first compartment 11 is smaller than the average pore size Do of the pores opening on the side of the second compartment 12. In other words, each pore on the partition wall almost presents a conical structure, that is, the pore size of each pore has a trend of "gradually increasing along the direction of airflow movement"; wherein, the small-aperture air inlet can block the unburned and oxidized soot particles outside the conical pores, so that these soot particles temporarily stay in the first compartment 11. In some embodiments of the present invention, the first compartment 1 1 is coated with a catalyst that can catalyze the full oxidation reaction of the soot particles. After the soot particles are fully oxidized in the first compartment 11 by the catalyst, they can enter the conical pores and reach the second compartment 12 under the influence of the airflow. In addition, the large-aperture air outlet of the conical pores can, on the one hand, prevent the particles carried by the airflow from remaining inside the pores and causing blockage. On the other hand, it allows a portion of the catalyst coated in the second compartment 12 to be coated around the air outlet of the conical pores, that is, the coating area for the catalyst coated in the second compartment 12 is increased. It can be understood that the larger the catalyst coating area, the more conducive it is to fully promoting the reaction.

[0088] In some embodiments of the present invention, in at least one of the air holes, the number of its openings on the side of the first compartment 11 is at least two, and the aperture of at least one of the openings on the side of the first compartment 11 is smaller than the aperture of the air hole and the aperture of the opening on the side of the second compartment 12. Specifically, referring to the air hole on the left side of Figure 7, it has two air inlet openings on the side of the first compartment 11 and one air outlet opening on the side of the second compartment 12, that is, the gas from the first compartment 11 enters the interior of the air hole through the two air inlet openings and finally enters the second compartment 12 through the only air outlet opening of the air hole.

[0089] In some embodiments of the present invention, in at least one of the air holes, the number of its openings on the side of the second compartment 12 is at least two, and the aperture of at least one of the openings on the side of the second compartment 12 is larger than the aperture of the opening of the air hole on the side of the first compartment 11. Specifically, referring to the air hole on the right side of Figure 7, it has only one air inlet opening on the side of the first compartment 11 but has two air outlet openings on the side of the second compartment 12, that is, the gas from the first compartment 11 enters the interior of the air hole through the single air inlet opening and finally enters the second compartment 12 through the two air outlet openings of the air hole.

[0090] In some embodiments of the present invention, the average pore size Di∈[8,20] of the pores opening on one side of the first compartment 11 is in micrometers, preferably, Di∈[12,20] in micrometers. It is understandable that the size range of Di is selected so as to preferably isolate the soot particles generated by incomplete combustion of diesel from the pores. Thus, in some embodiments of the present invention, when a catalyst that promotes the full oxidation and combustion of the soot particles is coated in the first compartment 11, the pores that meet the above-mentioned Di size design principle can temporarily isolate the soot particles in the first compartment 11, and then the soot particles can be carried by the airflow through the pores to reach the second compartment 12.

[0091] In some embodiments of the present invention, the average pore diameter Do∈[11,23], in micrometers, of the pores opening on one side of the second compartment 12 is preferably Do∈[15,23], in micrometers. It is worth noting that the larger pore diameter of the conical pores increases the catalyst coating area when the catalyst is subsequently applied to the second compartment 12. A larger catalyst coating area is more conducive to the catalytic reaction.

[0092] In some embodiments of the present invention, the cross-sections of the first compartment 11 and the second compartment 12 are both square or rectangular. It is understood that a first compartment 11 having a square or rectangular cross-section is surrounded on all four sides by adjacent second compartments 12. This allows gas entering the first compartment 11 to directly enter the second compartment 12 after exiting, thereby improving the compactness of the ceramic unit and reducing space and material waste.

[0093] In some embodiments of the present invention, the first compartment 11 and the second compartment 12 are alternately arranged in a checkerboard pattern in the cross section of the ceramic unit body; this design concept can improve the structural compactness of the ceramic unit body and reduce space and material waste.

[0094] In some embodiments of the present invention, the thickness of the partition wall is 3 to 10 mil (about 75 to 250 μm), preferably 5 to 8 mil (about 125 to 200 μm). It is worth noting that the thickness of the partition wall of the ceramic unit body is set within this range. On the one hand, it can reduce the pressure difference between the air inlet side 01 and the air outlet side 02 of the ceramic unit body. It can be understood that the smaller the pressure difference, the more conducive to the circulation of gas and the purification reaction. The thicker the wall, the deeper the pores and the longer the flow path of the air flow in the pores, which will eventually lead to a larger pressure difference between the air inlet side 01 and the air outlet side 02 of the ceramic unit body. On the other hand, the appropriate wall thickness can ensure that the ceramic unit body has sufficient rigidity to avoid deformation, brittle fracture and other problems during service.

[0095] In some embodiments of the present invention, the porosity of the ceramic unit body is 35-55%, preferably 35-45%. Porosity is the ratio of the volume of the pores to the total volume of the material. It is worth noting that the porosity of the ceramic unit body is set within this range. On the one hand, it can reduce the pressure difference between the air inlet side 01 and the air outlet side 02 of the ceramic unit body. It can be understood that the smaller the pressure difference, the more conducive it is to the circulation of gas and the progress of the purification reaction; on the other hand, the appropriate porosity can ensure that the ceramic unit body has sufficient rigidity to avoid deformation, brittle fracture and other problems during service.

[0096] In some embodiments of the present invention, the distribution density of the pores on the partition wall, also known as the porosity, is 35-55%. The "distribution density" refers to the ratio of the cross-sectional area of ​​the pores to the area of ​​the partition wall. It is worth noting that the distribution density of the pores of the ceramic unit body is set within this range. On the one hand, it can reduce the pressure difference between the air inlet side 01 and the air outlet side 02 of the ceramic unit body. It can be understood that the smaller the pressure difference, the more conducive it is to the circulation of gas and the purification reaction; on the other hand, the appropriate pore distribution density can ensure that the ceramic unit body has sufficient rigidity to avoid deformation, brittle fracture and other problems during service.

[0097] In some embodiments of the present invention, the compartment density of the compartment in the cross section of the ceramic unit body, that is, the pore density is 200 to 500 meshes. It is worth noting that the compartment density of the ceramic unit body is set within this range. On the one hand, it can reduce the air pressure difference between the air inlet side 01 and the air outlet side 02 of the ceramic unit body. It can be understood that the smaller the air pressure difference, the more conducive it is to the circulation of gas and the progress of the purification reaction; on the other hand, the appropriate compartment density can ensure that the ceramic unit body has sufficient rigidity to avoid deformation, brittle fracture and other problems during service. In addition, under certain conditions, a larger compartment density can increase the coating area of ​​the catalyst to facilitate the full promotion of the reaction.

[0098] In some embodiments of the present invention, the cross-sectional area of ​​the first compartment is larger than that of the second compartment. It is worth noting that the larger first compartment can significantly reduce the back pressure of the honeycomb ceramic after the filter captures soot particles, thereby reducing energy consumption. Furthermore, the first compartment can contain a higher content of oxidation catalyst, effectively converting captured soot particles. This allows for passive regeneration at lower temperatures to convert more soot particles, reducing the need for active filter regeneration.

[0099] In some embodiments of the present invention, a cross-sectional area of ​​the first compartment is smaller than a cross-sectional area of ​​the second compartment.

[0100] In some embodiments of the present invention, the cross-sectional area of ​​the first compartment is equal to the cross-sectional area of ​​the second compartment.

[0101] Second aspect

[0102] Referring to Figure 8, a method for preparing the above-mentioned ceramic unit body includes the following steps: A1, dry-mixing silicon carbide powder, silicon powder, alkaline earth metal carbonate, metal oxide powder, additives, binders and pore-forming agents; A2, wet-mixing the dry mixture obtained in step A1 with water and a lubricant; A3, kneading, slurrying, extrusion molding, drying, plugging, degreasing and sintering the wet mixture obtained in step A2 to obtain the ceramic unit body; wherein the sintering in step A3 includes oxygen-free sintering and oxidation sintering performed in sequence, and the process of oxidation sintering is: exposing the air inlet end 01 of the green body that has completed oxygen-free sintering to the air, and performing negative pressure extraction on the air outlet end 02 of the green body, so that air is allowed to leave the green body from the air inlet end 01 of the green body through the first compartment 11, the pores, the second compartment 12 in sequence, and then from the air outlet end 02 to form the pores, so that the average pore diameter Do of the opening of the pores on the side of the second compartment 12 is larger than the average pore diameter Di of the opening on the side of the first compartment 11.

[0103] It is understandable that when preparing the above-mentioned ceramic unit body, the method of "pore-forming agent in the raw material" is used to form pores, which makes the morphology of the pores on the partition wall of the final product different; however, the present invention prepares the ceramic unit body by "first oxygen-free sintering, then oxidation sintering", so that the end of the pore close to the air inlet side 01 is oxidized first, so that the small-sized silicon at this position is oxidized into larger-sized silicon dioxide, so that most of the pores can achieve the effect of "the aperture of the air inlet port is smaller than the aperture of the air outlet port, thereby obtaining pores with a conical structure".

[0104] In some embodiments of the present invention, a plowshare high-speed mixer is used for dry mixing, the dry mixing time is 10 to 30 minutes, and the dry mixing speed is 50 to 200 rpm.

[0105] In some embodiments of the present invention, the wet mixing time is 1 to 20 minutes, and the wet mixing speed is 50 to 200 rpm.

[0106] In some embodiments of the present invention, a biaxial kneader is used for kneading, and the kneading time is 30 to 180 minutes.

[0107] In some embodiments of the present invention, in step A1, the negative pressure used in the negative pressure extraction is (-0.05) to (-0.02) MPa.

[0108] In some embodiments of the present invention, in step A1, the silicon carbide powder includes a first silicon carbide powder having an average particle size of 20 to 30 μm and a second silicon carbide powder having an average particle size of 3 to 8 μm.

[0109] In some embodiments of the present invention, in step A1, based on the total amount of the silicon carbide powder being 100 wt.%, the first silicon carbide powder accounts for 70 to 95 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 5 to 30 wt.% of the total silicon carbide powder.

[0110] In some embodiments of the present invention, in steps A1 and A2, based on 100 wt.% of the total raw materials, the silicon carbide powder accounts for 50-75 wt.%, preferably 50-65 wt.%, the silicon powder accounts for 15-25 wt.%, preferably 15-20 wt.%, the alkaline earth metal carbonate accounts for 1-2 wt.%, the metal oxide powder accounts for 0.2-1 wt.%, the additive accounts for 0.5-1.5 wt.%, the binder accounts for 6-15 wt.%, the pore-forming agent accounts for 3-18 wt.%, and the lubricant accounts for 5-11 wt.%. The mass percentage of the total raw materials is the sum of the mass percentages of the individual raw materials, excluding the mass of water.

[0111] In some embodiments of the present invention, the average particle size of the silicon powder is 3-10 μm, the average particle size of the alkaline earth metal carbonate is 2-6 μm, the average particle size of the metal oxide is 3-8 μm, and the average particle size of the pore-forming agent is 8-40 μm.

[0112] In some embodiments of the present invention, the alkaline earth metal carbonate is selected from at least one of magnesium carbonate, strontium carbonate, barium carbonate, and calcium carbonate.

[0113] In some embodiments of the present invention, the metal oxide is selected from at least one of aluminum oxide and titanium oxide.

[0114] In some embodiments of the present invention, the auxiliary agent is selected from at least one of bentonite and kaolin.

[0115] In some embodiments of the present invention, the binder is selected from at least one of organic alcohols, potassium laurate, modified cellulose, polyethylene oxide, and polyvinyl pyrrolidone. The organic alcohols include monohydric alcohols, dihydric alcohols, and polyhydric alcohols, preferably C1-C8, and more preferably C1-C4 monohydric alcohols, dihydric alcohols, and polyhydric alcohols. Examples of the organic alcohols include, but are not limited to, 1,2-propylene glycol, ethylene glycol, butylene glycol, 1,3-propylene glycol, and pentaerythritol. The modified cellulose includes, but is not limited to, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, and propyl cellulose.

[0116] In some embodiments of the present invention, the pore-forming agent is selected from at least one of walnut powder, graphite, benzoic acid, starch, ammonium bicarbonate, ammonium chloride, polymethyl methacrylate, and expanded microspheres.

[0117] In some embodiments of the present invention, the lubricant is glycerol.

[0118] The third aspect

[0119] A honeycomb ceramic carrier is composed of the above-mentioned ceramic unit bodies or the ceramic unit bodies produced by the above-mentioned method. The ceramic unit bodies are distributed and connected in the cross section of the honeycomb ceramic carrier, and the longitudinal direction of the ceramic unit bodies is the same as the longitudinal direction of the honeycomb ceramic carrier.

[0120] In some embodiments of the present invention, the thermal conductivity of the honeycomb ceramic support is 5 to 30 W / m·K, preferably 10 to 30 W / m·K, and more preferably 13 to 25 W / m·K.

[0121] In some embodiments of the present invention, the honeycomb ceramic carrier is a cylinder or a polygonal prism.

[0122] The fourth aspect

[0123] Referring to Figure 9, the present invention provides a method for preparing the above-mentioned honeycomb ceramic carrier, comprising the following steps: B1, providing the above-mentioned ceramic unit body, or providing a ceramic unit body prepared by the above-mentioned method; B2, subjecting the ceramic unit bodies to splicing, grinding, and grafting treatments in sequence to obtain the honeycomb ceramic carrier.

[0124] The fifth aspect

[0125] The present invention provides an exhaust gas catalytic core, comprising: the above-mentioned honeycomb ceramic carrier or the honeycomb ceramic carrier prepared by the above-mentioned method; a first catalyst applied to the inner wall surface of the first compartment 11 of the honeycomb ceramic carrier; a second catalyst applied to the inner wall surface of the second compartment 12 of the honeycomb ceramic carrier; referring to Figures 6 and 7, the first compartment 11 is open on one side of the air inlet end 01 and blocked on one side of the air outlet end 02, and the second compartment 12 is blocked on one side of the air inlet end 01 and open on one side of the air outlet end 02.

[0126] In some embodiments of the present invention, the exhaust gas catalytic core is used to catalyze exhaust gas containing soot particles, the first catalyst is used to promote oxidation of the soot particles, and the second catalyst is used to catalyze carbon monoxide, hydrocarbons, and nitrogen oxides.

[0127] In some embodiments of the present invention, the first catalyst is a DPF, ie, a diesel particle filter; and the second catalyst is a DOC, ie, a diesel oxidation catalyst.

[0128] The present invention designs the aforementioned ceramic unit, honeycomb ceramic substrate, and exhaust gas catalytic core. The concept is to provide a system that integrates the functions of a DPF and a DOC while fully utilizing the pore structure of a wall-flow honeycomb ceramic. Simultaneously loading both the DPF and DOC oxidation catalysts, the silicon carbide DPF and DOC honeycomb ceramic substrate is crucial for effectively reducing the overall volume and cost of the aftertreatment system. After loading, the regeneration temperature equilibrium point is lower, and the capture efficiency and exhaust gas conversion rate are similar to those of a DPF+DOC exhaust gas treatment system. This also reduces the volume and cost of diesel vehicle exhaust systems.

[0129] The silicon carbide honeycomb ceramic substrate, which can be coated with an oxidation catalyst, increases the contact area between the catalyst and the reactant gases by controlling the substrate's pore density and increasing the open area on the substrate's outlet side. Simultaneously coating both DPF and DOC catalysts, the substrate achieves exhaust gas conversion and particle capture efficiencies comparable to those of a DPF+DOC exhaust system, saving both volume and cost in diesel vehicle exhaust systems.

[0130] Example 1

[0131] In this embodiment, 54.5wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 88wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 12wt.% of the total silicon carbide powder, 19% of metallic silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 10% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 10% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 300 mesh die with a wall thickness of 3mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.02MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.946mm 2 , the cross-sectional area of ​​the second compartment is 1.177 mm 2 .

[0132] Example 2

[0133] In this embodiment, 56.5wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 88.5wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 11.5wt.% of the total silicon carbide powder, 20% of metallic silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 9% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 8% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes. After the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 300 mesh die with a wall thickness of 6mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.946mm 2, the cross-sectional area of ​​the second compartment is 1.177 mm 2 .

[0134] Example 3

[0135] In this embodiment, 59 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 88 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 12 wt.% of the total silicon carbide powder, 20% of metallic silicon powder, 1% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of additive, 7% of binder, and 3% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 8% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 300 mesh die with a wall thickness of 8 mils. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.946mm 2 , the cross-sectional area of ​​the second compartment is 1.177 mm 2 .

[0136] Example 4

[0137] In this embodiment, 61wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 86wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 14wt.% of the total silicon carbide powder, 20% of metallic silicon powder, 1.5% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 0.5% of additives, 6.5% of binder, and 3% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 7% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The obtained raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 3mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.04MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550mm 2 , the cross-sectional area of ​​the second compartment is 0.912mm 2 .

[0138] Example 5

[0139] In this embodiment, 60wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 91.7wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 8.3wt.% of the total silicon carbide powder, 18% of metallic silicon powder, 2% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1.5% of additives, 7% of binder, and 3% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 8% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 6mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550mm 2, the cross-sectional area of ​​the second compartment is 0.912mm 2 .

[0140] Example 6

[0141] In this embodiment, 63wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 90wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 10wt.% of the total silicon carbide powder, 19% of metallic silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 0.5% of additives, 6% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 6% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 8mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550mm 2 , the cross-sectional area of ​​the second compartment is 0.912mm 2 .

[0142] Example 7

[0143] In this embodiment, 60wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 75wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 25wt.% of the total silicon carbide powder, 16% of metallic silicon powder, 2% of alkaline earth metal carbonate, 1% of metal oxide powder, 1.5% of additives, 7.5% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 8% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 500 mesh die with a wall thickness of 3mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.188mm 2 , the cross-sectional area of ​​the second compartment is 0.716mm 2 .

[0144] Example 8

[0145] In this embodiment, 61wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 84wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 16wt.% of the total silicon carbide powder, 17% of metallic silicon powder, 1.5% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 7% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 8% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 500 mesh die with a wall thickness of 6mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.05MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.188mm 2, the cross-sectional area of ​​the second compartment is 0.716mm 2 .

[0146] Example 9

[0147] In this embodiment, 61wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 75wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 25wt.% of the total silicon carbide powder, 15% of metallic silicon powder, 2% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of additive, 8% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 8% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 500 mesh die with a wall thickness of 8mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.05MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.188mm 2 , the cross-sectional area of ​​the second compartment is 0.716mm 2 .

[0148] Example 10

[0149] In this embodiment, 58 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 86 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 14 wt.% of the total silicon carbide powder, 16% of metallic silicon powder, 2% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 9% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 9.5% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; the kneaded mud is kneaded and then put into an extruder and extruded into a unit body using a 300 mesh die with a wall thickness of 6 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.946mm 2 , the cross-sectional area of ​​the second compartment is 1.177 mm 2 .

[0150] Example 11

[0151] In this embodiment, 55wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 93wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 17wt.% of the total silicon carbide powder, 15% of metallic silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 0.5% of additives, 7% of binder, and 15% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 6% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 300 mesh die with a wall thickness of 6mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.946mm 2, the cross-sectional area of ​​the second compartment is 1.177 mm 2 .

[0152] Example 12

[0153] In this embodiment, 59 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 87 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 13 wt.% of the total silicon carbide powder, 18% of metallic silicon powder, 2% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 13.5% of binder, and 5% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 8% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 6 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550mm 2 , the cross-sectional area of ​​the second compartment is 0.912mm 2 .

[0154] Example 13

[0155] In this embodiment, 51wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 84wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 16wt.% of the total silicon carbide powder, 15% of metallic silicon powder, 2% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of additive, 7% of binder, and 15% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 8% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes. After the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 6mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550mm 2 , the cross-sectional area of ​​the second compartment is 0.912mm 2 .

[0156] Example 14

[0157] In this embodiment, 56 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 82 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 18 wt.% of the total silicon carbide powder, 18% of metallic silicon powder, 2% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 9% of binder, and 3% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 10.5% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; the kneaded mud material is kneaded and then put into an extruder and extruded into a unit body using a 500 mesh die with a wall thickness of 6 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.188mm 2, the cross-sectional area of ​​the second compartment is 0.716mm 2 .

[0158] Example 15

[0159] In this embodiment, 54 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 89 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 11 wt.% of the total silicon carbide powder, 16% of metallic silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 6.5% of binder, and 15% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 6% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 500 mesh die with a wall thickness of 8 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.188mm 2 , the cross-sectional area of ​​the second compartment is 0.716mm 2 .

[0160] Example 16

[0161] In this embodiment, 56 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 82 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 18 wt.% of the total silicon carbide powder, 17% of metallic silicon powder, 2% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 9.5% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 10% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 200 mesh die with a wall thickness of 6 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 2.372mm 2 , the cross-sectional area of ​​the second compartment is 1.428mm 2 .

[0162] Example 17

[0163] In this embodiment, 54 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 84 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 16 wt.% of the total silicon carbide powder, 17% of metallic silicon powder, 1.5% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of auxiliary agent, 9% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 10.5% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 300 mesh die with a wall thickness of 12 mils. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.946mm 2, the cross-sectional area of ​​the second compartment is 1.177 mm 2 .

[0164] Example 18

[0165] In this embodiment, 58 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 83 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 17 wt.% of the total silicon carbide powder, 18% of metallic silicon powder, 1.5% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additive, 10% of binder, and 2% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 9% of lubricant and 35% of water by mass of the raw materials are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes. After the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 6 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550mm 2 , the cross-sectional area of ​​the second compartment is 0.912mm 2 .

[0166] Example 19

[0167] In this embodiment, 50 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 90 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 10 wt.% of the total silicon carbide powder, 15% of metallic silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 0.5% of additives, 6% of binder, and 20% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 7% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 6 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550mm 2 , the cross-sectional area of ​​the second compartment is 0.912mm 2 .

[0168] Comparative Example 1

[0169] In this embodiment, 57 wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 86 wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 14 wt.% of the total silicon carbide powder, 16% of metallic silicon powder, 2% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of additive, 9% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95 rpm. After the dry mixing is completed, 10% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95 rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 600 mesh die with a wall thickness of 3 mil. Then, it undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that the air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. The negative pressure at the outlet is -0.03MPa. Subsequently, the above-mentioned silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst is obtained through the steps of splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 0.884mm 2, the cross-sectional area of ​​the second compartment is 0.531 mm 2 .

[0170] Comparative Example 2

[0171] In this embodiment, 57wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 84wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 16wt.% of the total silicon carbide powder, 17% of metallic silicon powder, 2% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of auxiliary agent, 9% of binder, and 4% of pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 9% of lubricant and 35% of the raw material mass fraction of water are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The obtained raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 300 mesh die with a wall thickness of 3mil. It then undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, oxidation sintering, and oxidation sintering without negative pressure extraction process. The silicon carbide honeycomb ceramic substrate capable of being coated with an oxidation catalyst is obtained by sequentially performing steps such as splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.946 mm 2 , the cross-sectional area of ​​the second compartment is 1.177 mm 2 .

[0172] Comparative Example 3

[0173] In this embodiment, 57wt.% silicon carbide powder, of which the first silicon carbide powder accounts for 86wt.% of the total silicon carbide powder, and the second silicon carbide powder accounts for 14wt.% of the total silicon carbide powder, 16% metallic silicon powder, 2% alkaline earth metal carbonate, 1% metal oxide powder, 1% additive, 9% binder, and 4% pore-forming agent are added to a plow mixer and dry-mixed for 15 minutes at a rotation speed of 95rpm. After the dry mixing is completed, 10% lubricant and 35% water of the raw material mass fraction are added for wet mixing for 5 minutes at a rotation speed of 95rpm. The resulting raw material mixture is added to a biaxial kneader and kneaded for 60 minutes; after the kneaded mud is slurried, it is put into an extruder and extruded into a unit body using a 400 mesh die with a wall thickness of 6mil. It then undergoes microwave drying, pore plugging, degreasing, oxygen-free sintering, oxidation sintering, and oxidation sintering without negative pressure extraction. The silicon carbide honeycomb ceramic substrate capable of being coated with an oxidation catalyst is obtained by sequentially performing steps such as splicing, grinding, and grafting. The cross-sectional area of ​​the first compartment of the honeycomb ceramic unit body provided in this embodiment is 1.550 mm 2 , the cross-sectional area of ​​the second compartment is 0.912mm 2.

[0174] The types of raw materials in Examples 1 to 19 and Comparative Examples 1 to 3 are listed in Table 1 below.

[0175] Table 1 Types of raw materials for Examples 1 to 19 and Comparative Examples 1 to 3 (Silicon carbide powder, silicon powder, and lubricant are not listed)

[0176] The porosity of the honeycomb ceramic substrates obtained in the above-mentioned examples and comparative examples was measured using the water displacement method. Pore volume was measured using mercury intrusion porosimetry (Mercury Intrusion Porosimetry) using a MicroActive AutoPore V 9600 Version 2.03.00 mercury intrusion porosimeter (MicroActive AutoPore V 9600 Version 2.03.00, manufactured by Micromeritics, Inc., USA) on a 10 mm x 10 mm x 15 mm sample. The test method adhered to the national standard GB / T 21650.1-2008. The results are shown in Table 2 below.

[0177] The average pore diameter of the openings of the pores on the air inlet side and the average pore diameter of the openings of the pores on the air outlet side of the honeycomb ceramic carriers obtained in the above embodiments and comparative examples are obtained by the following method: (1) the partition wall of the honeycomb ceramic carrier is made into multiple 1mm*1mm samples, and the samples are divided into the inlet side and the outlet side. The same side is tested during the test process. The surface to be tested is placed in a scanning electron microscope (model: JS / YQ SEM-101) for scanning. The magnification is 400 times. 5 to 8 samples are randomly sampled, and a 500μm*500μm area is taken from each sample; (2) the pore diameters of the 1st to Nth areas (N is 5 to 8) are measured, and the average pore diameter D of each area is calculated. n (n is 1 to N); (3) Calculate D1 to D N The average value D of the above set of average data is calculated, and the standard deviation σ=sqrt(((D1-D) 2 +(D2-D) 2 +......+(D n -D) 2 ) / N), where n is 1 to N; (4) when the standard deviation σ is less than 1.5 μm, the average value is valid, that is, D is the average pore size on one side of the partition wall; the average pore size on the inlet side and the outlet side is obtained, and the results are shown in Table 2 below.

[0178] Thermal conductivity test method of the honeycomb ceramic carriers obtained in the above embodiments and comparative examples: The thermal conductivity of the honeycomb ceramic carriers of the above invention was tested using an LFA 467 laser thermal conductivity meter at a temperature range of 25-500°C and a heating range of 50K / min and is listed in Table 2 below.

[0179] It is worth noting that the “average pore diameter Di at the air inlet end” in Table 2 refers to the “average pore diameter of the opening of the pore on the air inlet side”, the “average pore diameter Do at the air outlet end” in Table 2 refers to the “average pore diameter of the opening of the pore on the air outlet side”, and the “difference in pore diameter between the air outlet end and the air inlet end” in Table 2 refers to the “difference between the average pore diameter of the opening of the pore on the air inlet side and the average pore diameter of the opening of the pore on the air outlet side”.

[0180] Table 2 Performance parameters of honeycomb ceramic supports obtained in various embodiments and comparative examples

[0181] The carriers prepared in Examples 1 to 19 were catalyst coated and subjected to back pressure amplification tests. The PN23 test method for the carriers coated with DOC and DPF catalysts was: the World Harmonized Transient Cycle (WHTC) was used to measure PN>23nm data. The test results are shown in Table 3.

[0182] The conversion rates of NO, CO and HC were measured, and the regeneration equilibrium temperature and light-off temperature were tested. The test results are shown in Table 3.

[0183] Coated catalyst: The DOC oxidation catalyst and the DPF oxidation catalyst are catalyst slurries containing precious metals, and the slurry coating contains aluminum oxide and / or oxides composed of rare earth elements.

[0184] The DPF oxidation catalyst is coated on the wall of the intake duct. The precious metals in the slurry coating include Pt and Pd. The mass ratio of Pt to Pd is 1:0-5:1, and the concentration of precious metals is 10g / ft 3 -20g / ft 3 .

[0185] The DOC oxidation catalyst is coated on the filter wall of the particulate filter from the outlet end. The precious metals in the catalyst on the filter wall include Pt and Pd. The mass ratio of Pt to Pd is 5:1-0:1, and the concentration of precious metals is 10g / ft 3 -20g / ft 3 .

[0186] Table 3 Catalytic performance of honeycomb ceramic supports obtained in various examples and comparative examples

[0187] It can be seen from Table 3 above that in Examples 1-19 of the present invention, the Do (pore size of the wall on the outlet side) - Di (pore size of the wall on the inlet side) satisfies the requirement of being greater than 3 μm, that is, the filter of the present invention meets the requirements of high capture efficiency, can load the DOC oxidation catalyst and the DPF oxidation catalyst at the same time, and has a high conversion rate of NOx, CO, and HC after loading.

[0188] Specifically, Comparative Example 1, with its higher mesh size, achieved similar NOx and HC conversion rates to those of the Examples. However, the high mesh size significantly increased the catalyst coating, hindering cost savings. Compared to the Examples, Comparative Examples 2 and 3 lacked negative pressure to extract air from the unit outlet, resulting in less pronounced oxidation. This resulted in less oxidation and sintering at the same inlet aperture, leading to larger apertures. This resulted in higher PN values ​​measured through the WHTC cycle and slightly lower NOx and HC conversion rates. Compared to Example 1, the reduced mesh size in Example 16 resulted in higher active regeneration conversion temperatures and regeneration equilibrium temperatures, adversely affecting energy efficiency. Compared with Example 1, Example 17 has a thicker wall thickness, which is not conducive to reducing the back pressure, and the thicker wall thickness will make its heat conduction slower, thereby increasing its active regeneration conversion temperature and regeneration equilibrium temperature point; the low porosity of Example 18 will also lead to a higher back pressure; the high porosity of Example 19 makes the structure of the honeycomb ceramic unstable and the compressive strength low. At the same time, the increased porosity reduces the thermal conductivity of the honeycomb ceramic carrier, thereby increasing the active regeneration conversion temperature and regeneration equilibrium temperature point of the carrier after being coated with the catalyst.

[0189] Therefore, the filter prepared by the present invention by improving the oxidation sintering means and the difference between the inlet and outlet diameters in the preparation process has both DOC oxidation catalyst and DPF oxidation catalyst, which can effectively improve the filtration efficiency and the conversion efficiency of emissions, reduce the catalyst coating pressure increase, and thus reduce the energy consumption of the vehicle.

[0190] The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims. In addition, the principle and implementation of the present invention are explained in detail in the specification using specific examples. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. The content of this specification should not be understood as limiting the present invention.

Claims

1. A ceramic unit, characterized in that, The two ends of the ceramic unit body in the longitudinal direction are respectively an air inlet end (01) and an air outlet end (02), and the ceramic unit body has a plurality of compartments separated by partition walls and extending along the longitudinal direction of the ceramic unit body; The compartments include a first compartment (11) and a second compartment (12) alternately arranged in the cross-section of the ceramic unit body. The first compartment (11) is open on one side of the air inlet end (01) and blocked on one side of the air outlet end (02). The second compartment (12) is blocked on one side of the air inlet end (01) and open on one side of the air outlet end (02); Wherein, a plurality of air holes connecting the first compartment and the second compartment are provided on the partition wall; the average pore diameter of the openings of the air holes on the side of the first compartment (11) is Di, and the average pore diameter of the openings of the air holes on the side of the second compartment (12) is Do, and Di < Do.

2. The ceramic unit according to claim 1, characterized in that, In at least one of the air holes, the number of openings on the side of the first compartment (11) is at least two, and the pore diameter of at least one of the openings on the side of the first compartment (11) is smaller than the pore diameter of the opening of the air hole on the side of the second compartment (12); And / or, in at least one of the air holes, the number of openings on the side of the second compartment (12) is at least two, and the pore diameter of at least one of the openings on the side of the second compartment (12) is larger than the pore diameter of the opening of the air hole on the side of the first compartment (11).

3. The ceramic unit according to claim 1 or 2, characterized in that, The average pore diameter Di of the air holes on the side of the first compartment (11) ∈ [8, 20], the unit is micrometer, preferably, Di ∈ [12, 20], the unit is micrometer; And / or, the average pore diameter Do of the openings of the air holes on the side of the second compartment (12) ∈ [11, 23], the unit is micrometer, preferably, Do ∈ [15, 23], the unit is micrometer.

4. The ceramic unit according to any one of claims 1 to 3, characterized in that, The cross-sectional shapes of the first compartment (11) and the second compartment (12) are both square or rectangular; And / or, the first compartment (11) and the second compartment (12) are alternately arranged in a checkerboard pattern in the cross-section of the ceramic unit body.

5. The ceramic unit according to any one of claims 1 to 4, characterized in that The thickness of the partition wall is 75 - 250 μm, preferably 125 - 200 μm; And / or, the cross-sectional area of the first compartment (11) is larger than the cross-sectional area of the second compartment (12), or the cross-sectional area of the first compartment (11) is smaller than the cross-sectional area of the second compartment (12), or the cross-sectional area of the first compartment (11) is equal to the cross-sectional area of the second compartment (12).

6. The ceramic unit according to any one of claims 1 to 5, characterized in that, The porosity of the ceramic unit body is 35 - 55%; And / or, the pore density of the compartments in the ceramic unit body is 200 - 500 mesh.

7. A method for preparing a ceramic unit as described in any one of claims 1 to 6, characterized in that, The method includes the following steps: A1, dry-mix silicon carbide powder, silicon powder, alkaline earth metal carbonate, metal oxide powder, additives, binder and pore-forming agent to obtain a dry-mixed material; A2, wet-mix the dry-mixed material obtained in step A1 with water and lubricant to obtain a wet-mixed material; A3. Knead, refine the wet mixture obtained in step A2, extrude into shape, dry, plug the holes, degrease, and sinter to obtain the ceramic unit body; Among them, the sintering in step A3 includes anaerobic sintering and oxidation sintering carried out in sequence. The process of oxidation sintering is as follows: expose the air inlet end (01) of the green body that has completed anaerobic sintering to air, perform negative pressure extraction on the air outlet end (02) of the green body, so that air sequentially passes through the first compartment (11), pores, and the second compartment (12) from the air inlet end (01) of the green body and then leaves the green body from the air outlet end (02) to form the pores, such that the average pore diameter Do of the opening on the side of the second compartment (12) is larger than the average pore diameter Di of the opening on the side of the first compartment (11); Preferably, a plow knife high-speed mixer is used for the dry mixing, the dry mixing time is 10 - 30 min, and the dry mixing rotation speed is 50 - 200 rpm; Preferably, the wet mixing time is 1 - 20 min, and the wet mixing rotation speed is 50 - 200 rpm; Preferably, a double-shaft kneader is used for kneading, and the kneading time is 30 - 180 min.

8. The method according to claim 7, characterized in that, In step A3, the magnitude of the negative pressure used for the negative pressure extraction is (-0.05) - (-0.02) MPa.

9. The method according to claim 7 or 8, characterized in that, In step A1, the silicon carbide powder includes a first silicon carbide powder with an average particle size of 20 - 30 μm and a second silicon carbide powder with an average particle size of 3 - 8 μm.

10. The method according to any one of claims 7 to 9, characterized in that In step A1, based on the total amount of the silicon carbide powder being 100 wt.%, the proportion of the first silicon carbide powder in the total silicon carbide powder is 70 - 95 wt.%, and the proportion of the second silicon carbide powder in the total silicon carbide powder is 5 - 30 wt.%.

11. The method according to any one of claims 7 to 10, characterized in that, In step A1, based on the mass of the total raw materials being 100 wt.%, the proportion of the silicon carbide powder is 50 - 75 wt.%, preferably 50 - 65 wt.%, the proportion of the silicon powder is 15 - 25 wt.%, preferably 15 - 20 wt.%, the proportion of the alkaline earth metal carbonate is 1 - 2 wt.%, the proportion of the metal oxide powder is 0.2 - 1 wt.%, the proportion of the auxiliary agent is 0.5 - 1.5 wt.%, the proportion of the binder is 6 - 15 wt.%, the proportion of the pore-forming agent is 3 - 18 wt.%, and the proportion of the lubricant is 5 - 11 wt.%.

12. The method according to any one of claims 7 to 11, characterized in that, The average particle size of the silicon powder is 3 - 10 μm, the average particle size of the alkaline earth metal carbonate is 2 - 6 μm, the average particle size of the metal oxide is 3 - 8 μm, and the average particle size of the pore-forming agent is 8 - 40 μm.

13. The method according to any one of claims 7 to 12, characterized in that, It has one or more of the following characteristics: The alkaline earth metal carbonate is selected from at least one of magnesium carbonate, strontium carbonate, barium carbonate, and calcium carbonate; The metal oxide is selected from at least one of alumina and titanium oxide; The auxiliary agent is selected from at least one of bentonite and kaolin; The binder is selected from at least one of organic alcohols, potassium laurate, modified cellulose, polyethylene oxide, and polyvinylpyrrolidone; The pore former is selected from at least one of walnut powder, graphite, benzoic acid, starch, ammonium bicarbonate, ammonium chloride, polymethyl methacrylate, and expandable microspheres; The lubricant is glycerol.

14. A honeycomb ceramic carrier, characterized in that, The honeycomb ceramic carrier is composed of the ceramic unit body described in any one of claims 1 to 6 or the ceramic unit body obtained by the method described in any one of claims 7 to 13. Each of the ceramic unit bodies is distributed and joined in the cross-section of the honeycomb ceramic carrier, and the longitudinal direction of the ceramic unit body is the same as the longitudinal direction of the honeycomb ceramic carrier.

15. The honeycomb ceramic carrier according to claim 14, wherein, The thermal conductivity of the honeycomb ceramic carrier is 5 to 30 W / m·K, preferably 10 to 30 W / m·K, and more preferably 13 to 25 W / m·K.

16. The honeycomb ceramic carrier according to claim 14 or 15, characterized in that, The honeycomb ceramic carrier is a cylinder or a prism.

17. A method for preparing a honeycomb ceramic carrier as described in any one of claims 14 to 16, characterized in that, The method includes the following steps: B1, providing the ceramic unit body described in any one of claims 1 to 6, or providing the ceramic unit body obtained by the method described in any one of claims 7 to 13; B2, after successively subjecting the ceramic unit body to splicing, skin grinding, and skin planting treatments, obtaining the honeycomb ceramic carrier.

18. An exhaust gas catalytic core, characterized in that, The tail gas catalytic core includes: The honeycomb ceramic carrier described in any one of claims 14 to 16 or the honeycomb ceramic carrier obtained by the method described in claim 17; A first catalyst, applied to the inner wall surface of the first compartment (11) of the honeycomb ceramic carrier; A second catalyst, applied to the inner wall surface of the second compartment (12) of the honeycomb ceramic carrier.

19. The exhaust gas catalytic core according to claim 18, characterized in that, The tail gas catalytic core is used for catalyzing the tail gas containing soot particles. The first catalyst is used to promote the oxidation of the soot particles, and the second catalyst is used to catalyze the conversion of carbon monoxide, hydrocarbons, and nitrogen oxides.

Images