Ceramic unit body, honeycomb ceramic carrier, preparation method of honeycomb ceramic carrier and tail gas catalysis core body

Abstract

The invention provides a ceramic unit body, a honeycomb ceramic carrier, a preparation method of the honeycomb ceramic carrier and a tail gas catalysis core body, the two ends of the ceramic unit body are a gas inlet end and a gas outlet end respectively, and the ceramic unit body is provided with a plurality of compartments which are partitioned by partition walls and extend in the longitudinal direction of the ceramic unit body; the compartments comprise first compartments and second compartments which are alternately arranged in the cross section of the ceramic unit body, the first compartments are opened on one side of the air inlet end and blocked on one side of the air outlet end, and the second compartments are blocked on one side of the air inlet end and opened on one side of the air outlet end; a plurality of air holes for communicating the first compartment with the second compartment are formed in the partition wall; the average aperture of the opening of the air holes in one side of the first compartment is Di, and the average aperture of the opening of the air holes in one side of the second compartment is Do, and Dilt; do. The ceramic unit body and the honeycomb ceramic carrier provided by the invention can improve the waste gas purification efficiency.

Description

Technical Field

[0001] The 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] The pollutants emitted by diesel vehicles mainly include carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and particulate matter (also known as PM, which is composed of dry soot, liquid hydrocarbons and a small amount of sulfate). Generally, in the exhaust gas purification device, a soot oxidation catalyst (DOC), a diesel soot filter (DPF), a reductant injector and a selective catalytic reduction (SCR) device are installed in sequence on the exhaust line that discharges the exhaust gas. The exhaust gas generated by the engine is applied to the soot oxidation catalyst, the diesel soot filter and the selective catalytic reduction device in sequence. The harmful substances contained in the exhaust gas are removed. The DOC oxidizes the carbon monoxide and hydrocarbons contained in the exhaust gas into carbon dioxide, and the filter collects the particulate matter (PM) contained in the exhaust gas and selectively catalytically reduces it. The device uses a reductant or a nitrogen group injected from a reductant injector to adsorb nitrogen oxides contained in the exhaust gas. The diesel particulate filter (DPF) is generally coated with a catalyst, which has the function of oxidizing accumulated soot and oxidizing 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 the waste needs to be solved urgently. Summary of the invention

[0004] The object of the present invention is to provide a ceramic unit body, a honeycomb ceramic carrier and a preparation method thereof, 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 the exhaust gas.

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

[0006] A ceramic unit body, wherein 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 are open on one side of the air inlet end and blocked on one side of the air outlet end, and the second compartments are 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 size of the pores opening on the first compartment side is Di, the average pore size of the pores opening on the second compartment side is Do, and Di <Do。

[0009] In some embodiments of the present invention, in at least one of the pores, the number of openings on the first compartment side is at least two, and the aperture of at least one of the openings on the first compartment side is smaller than the aperture of the pore opening 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 size 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 size 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 cell 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 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, binders and pore-forming agents to obtain a dry mix;

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

[0023] A3, kneading, kneading, 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, and the process of oxidation sintering is: exposing the air inlet end of the green body that has completed oxygen-free sintering to the air, performing negative pressure extraction on the air outlet end of the green body, so that air passes through the first compartment, the pores, and the second compartment from the air inlet end of the green body and then leaves the green body from the air outlet end to form the pores, so that the average pore diameter Do of the opening of the pores on the second compartment side is larger than the average pore diameter Di of the opening of the pores on the first compartment side;

[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 kneading machine 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 100wt.%, the silicon carbide powder accounts for 50-75wt.%, preferably 50-65wt.%, the silicon powder accounts for 15-25wt.%, preferably 15-20wt.%, the alkaline earth metal carbonate accounts for 1-2wt.%, the metal oxide powder accounts for 0.2-1wt.%, the auxiliary agent accounts for 0.5-1.5wt.%, the binder accounts for 6-15wt.%, the pore former accounts for 3-18wt.%, and the lubricant accounts for 5-11wt.%.

[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 former 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, which is composed of the above-mentioned ceramic unit bodies or ceramic unit bodies made 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 carrier 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 column.

[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 prepared 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, the exhaust gas catalytic core comprising:

[0049] The above honeycomb ceramic carrier 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 catalyst 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 the present 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 capable of simultaneously loading a DOC oxidation catalyst (i.e., a soot oxidation catalyst) and a DPF oxidation catalyst, wherein 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 simultaneously, wherein 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 drawings required for use in the description of the embodiments will be briefly introduced below. 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 paying any creative work.

[0058] Figure 1 A schematic diagram of the appearance of a honeycomb ceramic carrier in which the cross-sectional area of ​​the first compartment is larger than the cross-sectional area of ​​the second compartment provided in the first embodiment of the present invention;

[0059] Figure 2 for Figure 1 A schematic diagram of the structure of the honeycomb ceramic carrier at a first observation angle;

[0060] Figure 3 for Figure 2 A partial enlarged schematic diagram of the middle A area;

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

[0062] Figure 5 for Figure 4 A partial enlarged schematic diagram of the middle B area;

[0063] Figure 6 for Figure 1 A schematic diagram of a cross-sectional structure of a honeycomb ceramic carrier cut along its longitudinal direction;

[0064] Figure 7 for Figure 6 Schematic cross-section of the pores on the middle partition wall;

[0065] Figure 8 A flowchart of a method for preparing a ceramic unit body provided in a third embodiment of the present invention;

[0066] Fig. 9 A flowchart of a method for preparing a honeycomb ceramic substrate provided in a fourth embodiment of the present invention;

[0067] Fig.10 A SEM morphology image of the pores of the honeycomb ceramic carrier provided in the fifth embodiment of the present invention at the aperture sampling area on one side of the first compartment;

[0068] Fig.11 A SEM morphology image of the pores of the honeycomb ceramic carrier provided in the fifth embodiment of the present invention at the aperture sampling area on one side of the second compartment;

[0069] Fig.12 A SEM morphology image of the pores of the honeycomb ceramic carrier provided in the fifth embodiment of the present invention after partial enlargement of the aperture sampling area on one side of the first compartment;

[0070] Fig.13 A SEM morphology image of the pores of the honeycomb ceramic carrier provided in the fifth embodiment of the present invention after partial enlargement of the aperture sampling area on one side of the first compartment;

[0071] Fig.14 This is a SEM morphology of the partition wall of the honeycomb ceramic carrier provided in the fifth embodiment of the present invention. The main reference numerals in the drawings of the present invention specification are explained as follows:

[0072] 01-inlet side; 02-outlet side; 11-first compartment; 12-second compartment. DETAILED DESCRIPTION

[0073] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work belong to 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 used to limit the present invention.

[0074] Any specific numerical value disclosed herein (including the endpoint of the numerical range) is not limited to the exact value of the numerical value, but should be understood to also cover values ​​close to the exact value, such as all possible numerical values ​​within the range of ±5% of the exact value. In addition, for the disclosed numerical range, the endpoint values ​​of the range, the endpoint values ​​and the specific point values ​​in the range, and the specific point values ​​can be arbitrarily combined to obtain one or more new numerical ranges, and these new numerical ranges should also be regarded as specifically disclosed herein.

[0075] The terms used in the present disclosure are only intended to describe specific exemplary embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "a kind of" and "the" as used in the present disclosure may be intended to also include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive, thus illustrating 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 term "comprise" should be understood as a non-limiting term for describing and claiming the various embodiments described in the present disclosure, in some aspects, the term may be alternatively understood as a more restrictive and limited term, such as "consisting of..." or "consisting essentially of..." Thus, for any given embodiment of a narration composition, material, component, element, feature, integer, operation and / or process step, the present disclosure also particularly includes an embodiment consisting of or essentially 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 the embodiments.

[0076] Any method steps, processes, and operations described in the present disclosure should not be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless expressly identified as a certain order of performance. It should also be understood that additional or alternative steps may be used unless otherwise stated.

[0077] In the present invention, except for the contents explicitly described, any matters or items not mentioned are directly applicable to those known in the art without any change. Moreover, any embodiment described in the present disclosure can be freely combined with one or more other embodiments described in the present disclosure, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new contents that have not been disclosed or anticipated in the present disclosure, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0078] 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.

[0079] Unless otherwise stated, when % is mentioned herein, it means wt. %.

[0080] It is worth noting that the DOC recorded in the specification of the present invention refers to Diesel Oxidation Catalyst, i.e., diesel oxidation catalyst; and DPF refers to Diesel Particulate Filter, i.e., diesel particulate filter.

[0081] It is worth noting that the soot particles described in the specification of the present invention, also known as PM, are composed of dry soot, liquid hydrocarbons and a small amount of sulfate. The soot particles can be regarded as the product produced during the incomplete combustion of diesel. The ceramic unit body, honeycomb ceramic carrier and exhaust gas catalytic core provided by the present invention can promote the efficiency of passive regeneration of the soot particles, where "passive regeneration" refers to "removing particulate matter in the particle trap by reducing the activation energy of the oxidation reaction of the soot particles without external energy or intervention, and only using the heat brought by the exhaust gas to complete the reaction."

[0082] In the context of the present disclosure, Di represents the average pore size of the openings of the pores on the first compartment side, and Do represents the average pore size of the openings of the pores on the second compartment side.

[0083] In the context of the present disclosure, cell density refers to the number of compartments per square inch of area, in mesh; wherein the compartments include both the first compartment and the second compartment.

[0084] It is worth noting that, in some embodiments of the present invention, the above-mentioned tail gas catalyst core can be used for catalytic purification of tail gas or waste gas, and more specifically, can be used for waste gas or tail gas generated by incomplete combustion of diesel.

[0085] First aspect

[0086] See also Figures 1 to 7 , a ceramic unit cell, see Figure 6 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 in the longitudinal direction of the ceramic unit body; see Figures 2 to 5 , the compartments include first compartments 11 and second compartments 12 alternately arranged in a cross section of the ceramic unit body; see Figure 6 and Figure 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, see Figure 7The average pore size of the pores opening on the first compartment 11 side is Di, the average pore size of the pores opening on the second compartment 12 side is Do, and Di <Do。

[0087] 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.

[0088] Specifically, the ceramic unit body provided by the present invention has a unique structural design of the partition wall between the two compartments inside it: Figure 6 and Figure 7 , the average pore size Di of the pores opening on one side of the first compartment 11 is smaller than the average pore size Do of the pores opening on one 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 "the pore size gradually increases 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 the soot particles temporarily stay in the first compartment 11. In some embodiments of the present invention, the first compartment 11 is coated with a catalyst that can catalyze the soot particles to fully oxidize and react. When the soot particles are fully oxidized by the catalyst in the first compartment 11, 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 prevent the particles carried by the airflow from remaining inside the pores and causing blockage, and can also allow a part of the catalyst applied in the second compartment 12 to be applied around the air outlet of the conical pores, that is, the coating area of ​​the catalyst applied 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 promote the reaction.

[0089] In some embodiments of the present invention, in at least one of the pores, the number of openings on the first compartment 11 side is at least two, and the aperture of at least one of the openings on the first compartment 11 side is smaller than the aperture of the pore and the opening on the second compartment 12 side. Figure 7 The air hole on the left side 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.

[0090] In some embodiments of the present invention, in at least one of the pores, the number of its openings on the second compartment 12 side is at least two, and the aperture of at least one of the openings on the second compartment 12 side is larger than the aperture of the opening of the pore on the first compartment 11 side. For details, see Figure 7 The air hole on the right side has only one air inlet opening on the side of the first compartment 11 but two air outlet openings on the side of the second compartment 12, that is, the gas from the first compartment 11 enters the second compartment 12 through the only air inlet opening and then into the air hole and finally through the two air outlet openings of the air hole.

[0091] 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, regarding the selection of the size range of Di, it is best to isolate the soot particles generated by the incomplete combustion of diesel from the pores. Thus, in some embodiments of the present invention, when the first compartment 11 is coated with a catalyst that can promote the full oxidation and combustion of the soot particles, the pores that meet the above Di size design principle can temporarily isolate the soot particles in the first compartment 11, and then the soot particles can pass through the pores under the airflow to reach the second compartment 12.

[0092] In some embodiments of the present invention, the average pore size Do∈[11,23] of the pores opening on one side of the second compartment 12 is in micrometers, preferably, Do∈[15,23] in micrometers. It is worth noting that the larger pore size structure of the conical pores can increase the coating area of ​​the catalyst when the catalyst is subsequently coated on the second compartment 12, and the larger the catalyst coating area, the more conducive to the catalytic reaction.

[0093] 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 understandable that a first compartment 11 having a square cross-section or a rectangular cross-section is surrounded by second compartments 12 adjacent thereto on all four sides, so that the gas entering the first compartment 11 can directly enter the second compartment 12 after leaving, thereby improving the compactness of the ceramic unit structure and reducing the waste of space and materials.

[0094] 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 compactness of the ceramic unit body and reduce the waste of space and materials.

[0095] 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.

[0096] 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 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 to the circulation of gas and 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.

[0097] 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 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.

[0098] 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 to the circulation of gas and 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.

[0099] In some embodiments of the present invention, the cross-sectional area of ​​the first compartment is greater than the cross-sectional area of ​​the second compartment. It is worth noting that the larger first compartment can fully reduce the honeycomb ceramic back pressure after the filter captures the soot particles, reducing energy consumption, and at the same time, the first compartment is coated with a higher content of oxidation catalyst, which can effectively convert the captured soot particles, and passively regenerate and convert more soot particles at a lower temperature, reducing the active regeneration of the filter.

[0100] 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.

[0101] 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.

[0102] Second aspect

[0103] See also Figure 8 A method for preparing the above-mentioned ceramic unit body comprises the following steps: A1, dry-mixing silicon carbide powder, silicon powder, alkaline earth metal carbonate, metal oxide powder, additive, binder and pore-forming agent; A2, wet-mixing the dry mixture obtained in step A1 with water and 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 comprises 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 from the air inlet end 01 of the green body sequentially passes through the first compartment 11, the pores, the second compartment 12 and then leaves the green body from the air outlet end 02 to form the pores, so that the average pore size Do of the pores on the second compartment 12 side is larger than the average pore size Di of the pores on the first compartment 11 side.

[0104] It is understandable that when preparing the above-mentioned ceramic unit body, since the method of "pore-forming agent in the raw material" is used to form holes, the morphology of the pores on the partition walls in the final product is different; however, the present invention prepares the ceramic unit body by "first anaerobic sintering, then oxidative 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 to become 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".

[0105] 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.

[0106] 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.

[0107] In some embodiments of the present invention, a biaxial kneading machine is used for kneading, and the kneading time is 30 to 180 minutes.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] In some embodiments of the present invention, in the steps A1 and A2, based on the mass of the total raw materials being 100wt.%, the silicon carbide powder accounts for 50-75wt.%, preferably 50-65wt.%, the silicon powder accounts for 15-25wt.%, preferably 15-20wt.%, the alkaline earth metal carbonate accounts for 1-2wt.%, the metal oxide powder accounts for 0.2-1wt.%, the auxiliary agent accounts for 0.5-1.5wt.%, the binder accounts for 6-15wt.%, the pore former accounts for 3-18wt.%, and the lubricant accounts for 5-11wt.%. The mass percentage of the total raw materials is the sum of the mass percentages of the raw materials, excluding the mass of water.

[0112] 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 former is 8-40 μm.

[0113] 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.

[0114] In some embodiments of the present invention, the metal oxide is selected from at least one of aluminum oxide and titanium oxide.

[0115] In some embodiments of the present invention, the auxiliary agent is selected from at least one of bentonite and kaolin.

[0116] 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 alcohol includes monohydric alcohol, dihydric alcohol, and polyhydric alcohol, preferably C1-C8, more preferably C1-C4 monohydric alcohol, dihydric alcohol, and polyhydric alcohol. Examples of the organic alcohol include, but are not limited to, 1,2-propylene glycol, ethylene glycol, butanediol, 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.

[0117] 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.

[0118] In some embodiments of the present invention, the lubricant is glycerol.

[0119] The third aspect

[0120] A honeycomb ceramic carrier is composed of the above-mentioned ceramic unit bodies or the ceramic unit bodies made 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.

[0121] In some embodiments of the present invention, 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.

[0122] In some embodiments of the present invention, the honeycomb ceramic carrier is a cylinder or a polygonal column.

[0123] The fourth aspect

[0124] See also Fig. 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 obtained by the above-mentioned method; B2, subjecting the ceramic unit bodies to splicing, grinding and skin grafting treatments in sequence to obtain the honeycomb ceramic carrier.

[0125] Fifth Aspect

[0126] The present invention provides an exhaust gas catalytic core, comprising: the honeycomb ceramic carrier mentioned above or the honeycomb ceramic carrier prepared by the method mentioned above; 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; Figure 6 and Figure 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 .

[0127] 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.

[0128] In some embodiments of the present invention, the first catalyst is a DPF, namely a Diesel Particle Filter; and the second catalyst is a DOC, namely a Diesel Oxidation Catalyst.

[0129] The present invention designs the above-mentioned ceramic unit body, honeycomb ceramic carrier and exhaust gas catalytic core body, and its conception is to provide a kind of integrated DPF and DOC functions while making full use of the pore structure of wall-flow honeycomb ceramics, and at the same time load DPF oxidation catalyst and DOC oxidation catalyst, and effectively reduce the total volume and cost of the post-treatment system. The silicon carbide DPF and DOC honeycomb ceramic carriers are very important, and the regeneration temperature equilibrium point after loading is lower, and the capture efficiency and exhaust gas conversion rate are similar to those of the DPF+DOC exhaust gas treatment system. At the same time, the volume and cost of the diesel vehicle emission system are saved.

[0130] The silicon carbide honeycomb ceramic carrier that can be coated with an oxidation catalyst provided by the present invention increases the contact area between the catalyst and the reaction gas by controlling the pore density of the carrier and increasing the opening area on the outlet side of the carrier. Both DPF and DOC catalysts can be coated at the same time, and the conversion rate of exhaust gas and the particle capture efficiency are similar to those of the DPF+DOC exhaust system, saving the volume and cost of the exhaust system of diesel vehicles.

[0131] Example 1

[0132] 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 metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 10% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 300 mesh mold with a wall thickness of 3mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 .

[0133] Example 2

[0134] 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, the second silicon carbide powder accounts for 11.5wt.% of the total silicon carbide powder, 20% of metal silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of auxiliary agent, 9% of binder, and 4% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5 minutes and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading 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 mold with a wall thickness of 6mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 .

[0135] Example 3

[0136] In this embodiment, 59wt.% 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, 20% of metal silicon powder, 1% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of additives, 7% of binder, and 3% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 300 mesh mold with a wall thickness of 8mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 .

[0137] Example 4

[0138] In this embodiment, 61wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 86wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 14wt.% of the total silicon carbide powder, 20% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 7% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 3mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 .

[0139] Example 5

[0140] 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, the second silicon carbide powder accounts for 8.3wt.% of the total silicon carbide powder, 18% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 6mil. Then, it is subjected to 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. Among them, 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 skin 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 .

[0141] Example 6

[0142] In this embodiment, 63wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 90wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 10wt.% of the total silicon carbide powder, 19% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 6% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 8mil. Then, it is subjected to 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. Among them, 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 skin 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 .

[0143] Example 7

[0144] In this embodiment, 60wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 75wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 25wt.% of the total silicon carbide powder, 16% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 500 mesh mold with a wall thickness of 3mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 .

[0145] Example 8

[0146] In this embodiment, 61wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 84wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 16wt.% of the total silicon carbide powder, 17% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 500 mesh mold with a wall thickness of 6mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 .

[0147] Example 9

[0148] In this embodiment, 61wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 75wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 25wt.% of the total silicon carbide powder, 15% of metal silicon powder, 2% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of auxiliary agent, 8% of binder, and 4% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 500 mesh mold with a wall thickness of 8mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 .

[0149] Example 10

[0150] In this embodiment, 58wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 86wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 14wt.% of the total silicon carbide powder, 16% of metal silicon powder, 2% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of auxiliary agent, 9% of binder, and 4% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 9.5% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 300 mesh mold with a wall thickness of 6mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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 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, the second silicon carbide powder accounts for 17wt.% of the total silicon carbide powder, 15% of metal silicon powder, 1% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 0.5% of auxiliary agent, 7% of binder, and 15% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 6% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 300 mesh mold with a wall thickness of 6mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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, 59wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 87wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 13wt.% of the total silicon carbide powder, 18% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 6mil. Then, it is subjected to 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. Among them, 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 skin 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] Embodiment 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, the second silicon carbide powder accounts for 16wt.% of the total silicon carbide powder, 15% of metal silicon powder, 2% of alkaline earth metal carbonate, 1% of metal oxide powder, 1% of auxiliary agent, 7% of binder, and 15% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 8% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 6mil. Then, it is subjected to 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. Among them, 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 skin 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] Embodiment 14

[0157] In this embodiment, 56wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 82wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 18wt.% of the total silicon carbide powder, 18% of metal silicon powder, 2% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of auxiliary agent, 9% of binder, and 3% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, and the rotation speed is 95rpm. After the dry mixing is completed, 10.5% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, and the wet mixing time is 5min, and the rotation speed is 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 500 mesh mold with a wall thickness of 6mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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] Embodiment 15

[0159] In this embodiment, 54wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 89wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 11wt.% of the total silicon carbide powder, 16% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 6% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 500 mesh mold with a wall thickness of 8mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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, 56wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 82wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 18wt.% of the total silicon carbide powder, 17% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 10% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 200-mesh mold with a wall thickness of 6mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. 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. Among them, 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 skin 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 1.428 mm 2 .

[0162] Embodiment 17

[0163] In this embodiment, 54wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 84wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 16wt.% of the total silicon carbide powder, 17% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 10.5% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 300 mesh mold with a wall thickness of 12mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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] Embodiment 18

[0165] In this embodiment, 58wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 83wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 17wt.% of the total silicon carbide powder, 18% of metal silicon powder, 1.5% of alkaline earth metal carbonate, 0.5% of metal oxide powder, 1% of additives, 10% of binder, and 2% of pore-forming agent are added to a plow mixer for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 9% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 6mil. Then, it is subjected to 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. Among them, 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 skin 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] Embodiment 19

[0167] In this embodiment, 50wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 90wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 10wt.% of the total silicon carbide powder, 15% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing is completed, 7% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5 minutes and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60 minutes; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 6mil. Then, it is subjected to 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. Among them, 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 skin 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, 57wt.% of silicon carbide powder, of which the first silicon carbide powder accounts for 86wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 14wt.% of the total silicon carbide powder, 16% of metal 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 for dry mixing for 15 minutes, with a rotation speed of 95rpm. After the dry mixing, 10% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a double-shaft kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 600 mesh mold with a wall thickness of 3mil. Then, microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering are performed. During the oxidation sintering process, the outlet of the unit body is negatively pressured and extracted, so that air passes through the inlet side of the unit body, the porous partition wall, and the outlet side in sequence. Among them, 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 skin 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, the second silicon carbide powder accounts for 16wt.% of the total silicon carbide powder, 17% of metal 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 for dry mixing for 15min, with a rotation speed of 95rpm. After the dry mixing, 9% of lubricant and 35% of water by mass fraction of the raw materials are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a biaxial kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 300 mesh mold with a wall thickness of 3mil. It is then subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, oxidation sintering, and oxidation sintering without negative pressure extraction process. The silicon carbide honeycomb ceramic carrier that can be 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.% of silicon carbide powder, of which the first silicon carbide powder accounts for 86wt.% of the total silicon carbide powder, the second silicon carbide powder accounts for 14wt.% of the total silicon carbide powder, 16% of metal 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 for dry mixing for 15min, with a rotation speed of 95rpm. After the dry mixing, 10% of lubricant and 35% of water by mass fraction of the raw material are added for wet mixing, with a wet mixing time of 5min and a rotation speed of 95rpm. The obtained raw material mixture is added to a biaxial kneading machine for kneading for 60min; after the kneaded mud is kneaded, it is put into an extruder and extruded into a unit body using a 400 mesh mold with a wall thickness of 6mil. It is then subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, oxidation sintering, and oxidation sintering without negative pressure extraction process. The silicon carbide honeycomb ceramic carrier that can be 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 of the above Examples 1 to 19 and Comparative Examples 1 to 3 are listed in Table 1 below.

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

[0176]

[0177]

[0178] The porosity of the honeycomb ceramic carrier obtained in the above-mentioned embodiments and comparative examples was obtained by drainage method. The pore volume was tested by mercury intrusion method, by making a sample block with a length, width and height of 10mm*10mm*15mm by unit system, and measuring it by using the mercury intrusion instrument (MicroActive AutoPore V9600 Version 2.03.00) of American Micromeritics. The test method is the national standard: GB / T21650.1-2008, and the results are shown in Table 2 below.

[0179] The average pore size of the openings of the pores located on the air inlet side and the average pore size of the openings of the pores located on the air outlet side of the honeycomb ceramic carrier 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 a plurality of 1 mm*1 mm 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, and the magnification is 400 times. 5 to 8 samples are randomly sampled, and a 500 μm*500 μm area is taken from each sample; (2) The pore size of the 1st to Nth (N is 5 to 8) regions is measured, and the average pore size D of each region is calculated. n (n is 1 to N); (3) Calculate D1 to D N The average value D is calculated, and the standard deviation of the above set of average data is calculated as 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 sizes on the inlet and outlet sides are obtained, and the results are shown in Table 2 below.

[0180] 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 to 500°C and a heating range of 50K / min and is listed in Table 2 below.

[0181] It is worth mentioning that the “average pore size Di at the air inlet end” in Table 2 refers to the “average pore size of the opening of the pore on the air inlet side”, the “average pore size Do at the air outlet end” in Table 2 refers to the “average pore size of the opening of the pore on the air outlet side”, and the “aperture difference between the air outlet end and the air inlet end” in Table 2 refers to the “difference between the average pore size of the opening of the pore on the air inlet side and the average pore size of the opening of the pore on the air outlet side”.

[0182] Table 2 Performance parameters of honeycomb ceramic carriers obtained in various embodiments and comparative examples

[0183]

[0184]

[0185]

[0186] The carriers prepared in Examples 1 to 19 were coated with catalysts and subjected to back pressure amplification tests. The PN23 test method for the carriers coated with DOC and DPF catalysts was as follows: the World Harmonized Transient Cycle (WHTC) was used to measure PN>23nm data. The test results are shown in Table 3.

[0187] The conversion rates of NO, CO and HC were measured, and the regeneration equilibrium temperature and the light-off temperature were tested. The test results are shown in Table 3.

[0188] 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.

[0189] The DPF oxidation catalyst is coated on the wall of the intake channel. 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 .

[0190] The DOC oxidation catalyst is coated on the filter wall of the particle 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 .

[0191] Table 3 Catalytic performance of honeycomb ceramic carriers obtained in various embodiments and comparative examples

[0192]

[0193]

[0194] It can be seen from Table 3 above that in Examples 1-19 of the present invention, Do (pore size of the wall next to the outlet) - Di (pore size of the wall next to the inlet) satisfies being greater than 3 μm, that is to say, the filter of the present invention satisfies high capture efficiency, and can load both the DOC oxidation catalyst and the DPF oxidation catalyst at the same time, and has a high conversion rate for NOx, CO, and HC after loading.

[0195] Specifically, the mesh number of Comparative Example 1 is relatively high, and its NOx and HC conversion rates are similar to those of the embodiment, but its high mesh number greatly increases the amount of catalyst coating, which is not conducive to cost saving. Compared with the embodiment, Comparative Examples 2 and 3 do not use negative pressure to extract air from the outlet side of the unit body, and the oxidation effect is not significant, so that the inlet side pore diameter is the same, and the oxidation sintering is less, and the pore diameter is larger. The PN value measured after the WHTC cycle is higher, and the NOx and HC conversion rates are slightly lower. Compared with Example 1, the reduction in mesh number in Example 16 leads to an increase in the active regeneration conversion temperature and the regeneration equilibrium temperature point, which is not conducive to energy consumption. 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 after the carrier is coated with a catalyst.

[0196] Therefore, the filter prepared by the present invention by improving the oxidation sintering means and the inlet and outlet diameter difference in the preparation process has both DOC oxidation catalyst and DPF oxidation catalyst, which can effectively improve the filtration efficiency and emission conversion efficiency, reduce the catalyst coating pressure increase, and thus reduce automobile energy consumption.

[0197] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims. In addition, the specification uses specific examples to illustrate the principles and implementation methods of the present invention. 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 a limitation on the present invention.

Claims

1. A ceramic unit body, 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 in the longitudinal direction of the ceramic unit body; The compartments include a first compartment (11) and a second compartment (12) alternately arranged in a cross section of the ceramic unit body, the first compartment (11) being 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) being blocked on one side of the air inlet end (01) and open on one side of the air outlet end (02); 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 (11) side is Di, the average pore diameter of the pores opening on the second compartment (12) side is Do, and Di <Do。 2. The ceramic unit body according to claim 1, characterized in that: In at least one of the pores, the number of openings on the first compartment (11) side is at least two, and the aperture of at least one of the openings on the first compartment (11) side is smaller than the aperture of the opening of the pore on the second compartment (12) side; And / or, in at least one of the pores, 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 pore on the side of the first compartment (11).

3. The ceramic unit body according to claim 2, characterized in that: The average pore size Di∈[8,20] of the pores on one side of the first compartment (11) is in micrometers, preferably, Di∈[12,20], in micrometers; And / or, the average pore size of the opening of the pores on one side of the second compartment (12) is Do∈[11,23], in micrometers, preferably, Do∈[15,23], in micrometers.

4. The ceramic unit body according to claim 1, characterized in that: The cross-sections of the first compartment (11) and the second compartment (12) are both square or rectangular; And / or, the first compartments (11) and the second compartments (12) are arranged alternately in a checkerboard pattern in the cross section of the ceramic unit body.

5. The ceramic unit body according to any one of claims 1 to 4, characterized in that: The thickness of the partition wall is 75 to 250 μm, preferably 125 to 200 μm; And / or, the cross-sectional area of ​​the first compartment (11) is greater 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 body according to any one of claims 1 to 4, characterized in that: The porosity of the ceramic unit body is 35-55%; And / or, the cell density of the compartment in the ceramic unit body is 200-500 meshes.

7. A method for preparing the ceramic unit body according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: A1, dry-mixing silicon carbide powder, silicon powder, alkaline earth metal carbonate, metal oxide powder, additives, binders and pore-forming agents to obtain a dry mix; A2, wet-mixing the dry mixture obtained in step A1 with water and a lubricant to obtain a wet mixture; A3, kneading, kneading, extruding, drying, plugging, degreasing, and sintering the wet mixture obtained in step A2 to obtain the ceramic unit body; The sintering in step A3 includes oxygen-free sintering and oxidation sintering performed sequentially, and the process of oxidation sintering is as follows: 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 passes through the first compartment (11), the pores, the second compartment (12) and then leaves the green body from the air outlet end (02) in sequence from the air inlet end (01) of the green body, 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); 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; Preferably, the wet mixing time is 1 to 20 minutes, and the wet mixing speed is 50 to 200 rpm; Preferably, a biaxial kneading machine is used for kneading, and the kneading time is 30 to 180 minutes.

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

9. The method according to claim 7, characterized in that: In the 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.

10. The method according to claim 7, characterized in that In the 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.

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

12. The method according to claim 8 or 11, characterized in that: The average particle size of the silicon powder is 3 to 10 μm, the average particle size of the alkaline earth metal carbonate is 2 to 6 μm, the average particle size of the metal oxide is 3 to 8 μm, and the average particle size of the pore former is 8 to 40 μm.

13. The method according to claim 8 or 11, 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 aluminum oxide 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 polyvinyl pyrrolidone; 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; The lubricant is glycerin.

14. A honeycomb ceramic carrier, characterized in that: The honeycomb ceramic carrier is composed of a ceramic unit body as described in any one of claims 1 to 6 or a ceramic unit body prepared by the method as described in any one of claims 7 to 13, 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.

15. The honeycomb ceramic carrier according to claim 14, characterized in that: 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, characterized in that: The honeycomb ceramic carrier is a cylinder or a polygonal column.

17. A method for preparing the honeycomb ceramic carrier according to any one of claims 14 to 16, characterized in that: The method comprises the following steps: B1, providing a ceramic unit body as claimed in any one of claims 1 to 6, or providing a ceramic unit body prepared by the method as claimed in any one of claims 7 to 13; B2, the ceramic unit bodies are sequentially subjected to splicing, grinding and skin grafting processes to obtain the honeycomb ceramic carrier.

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

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