Honeycomb ceramic carrier and preparation method thereof, exhaust gas catalytic core

Abstract

The present invention provides a honeycomb ceramic substrate, a preparation method thereof, and an exhaust gas catalytic core. The honeycomb ceramic substrate contains silicon carbide, wherein the crystalline phases of the silicon carbide include 4H-SiC and 6H-SiC. The mass of the 4H-SiC accounts for 13% to 30% of the total mass of the honeycomb ceramic substrate, and the mass of the 6H-SiC accounts for 40% to 55% of the total mass of the honeycomb ceramic substrate. The porosity of the honeycomb ceramic substrate is 45% to 70%, preferably 50% to 65%. The honeycomb ceramic substrate provided by the present invention can achieve a higher cost-effectiveness while ensuring excellent porosity, pore volume, and thermal diffusivity.

Description

Technical Field

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

[0002] In some current technologies, honeycomb ceramic filters for efficient diesel engine particulate matter capture often utilize high-purity silicon carbide as the primary aggregate. 4H-SiC, 6H-SiC, 3C-SiC, and 15R-SiC are all different crystalline forms of silicon carbide, each with unique physical and chemical properties that determine their suitability and advantages in applications such as honeycomb ceramics. Below is a comparison of these crystalline forms in honeycomb ceramics: 3C-SiC, with its cubic lattice structure, differs from other hexagonal SiC crystalline forms and has relatively low thermal conductivity, making it unsuitable for applications requiring extremely high thermal conductivity. 15R-SiC, however, is less studied and has fewer applications than the other crystalline forms, requiring further investigation. 4H-SiC and 6H-SiC, due to their high thermal conductivity and excellent high-temperature stability, are well-suited for use in high-temperature honeycomb ceramics. Overall, 4H-SiC and 6H-SiC are more commonly used in high-temperature applications such as honeycomb ceramics due to their superior physical properties. Due to limited research, the potential of 15R-SiC in honeycomb ceramics remains to be explored. The choice of each crystal form will depend on the specific application and performance requirements. Currently, commercially available SiC honeycomb ceramic materials all utilize high-purity SiC, with 6H-SiC comprising over 90% by mass, resulting in a relatively high cost.

[0003] Therefore, seeking a honeycomb ceramic substrate with a higher cost performance has become an urgent problem to be solved in this field. Summary of the Invention

[0004] The object of the present invention is to provide a honeycomb ceramic substrate and a preparation method thereof, and an exhaust gas catalytic core, which have a higher cost-effectiveness while ensuring better porosity, pore volume and thermal diffusion coefficient.

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

[0006] A honeycomb ceramic carrier contains silicon carbide, the crystal phases of the silicon carbide include 4H-SiC and 6H-SiC, the mass of the 4H-SiC accounts for 13% to 30% of the total mass of the honeycomb ceramic carrier, the mass of the 6H-SiC accounts for 40% to 55% of the total mass of the honeycomb ceramic carrier, and the porosity of the honeycomb ceramic carrier is 45% to 70%, preferably 50% to 65%.

[0007] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC is 1:(2-4), preferably 1:(2-3).

[0008] In some embodiments of the present invention, the honeycomb ceramic carrier further contains elemental silicon, and the mass of the elemental silicon accounts for 10-25% of the total mass of the honeycomb ceramic carrier, preferably 15-25%;

[0009] And / or, the honeycomb ceramic support further contains silicon dioxide, and the mass of the silicon dioxide accounts for 5 to 25%, preferably 8 to 18%, of the total mass of the honeycomb ceramic support.

[0010] In some embodiments of the present invention, the thermal diffusion coefficient of the honeycomb ceramic substrate is 5 to 25 mm 2 / s, preferably 16 to 20 mm 2 / s.

[0011] In some embodiments of the present invention, the raw materials of the honeycomb ceramic carrier include a main material and an auxiliary material, wherein the main material includes two or three of the following: a first silicon carbide powder with a particle size of 30 to 50 μm, a second silicon carbide powder with a particle size of 15 to 30 μm, and a third silicon carbide powder with a particle size of less than 15 μm;

[0012] Preferably, the particle size of the first silicon carbide powder is 35 to 45 μm, the particle size of the second silicon carbide powder is 20 to 30 μm, and the particle size of the third silicon carbide powder is 4 to 12 μm.

[0013] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.15-0.25):1, preferably (0.17-0.23):1;

[0014] And / or, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.4):1, preferably (0.3-0.35):1;

[0015] And / or, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.25):1, preferably (0.15-0.2):1.

[0016] In some embodiments of the present invention, the main material further comprises elemental silicon powder, metal oxide, clay, and / or the auxiliary material comprises a binder and a pore-forming agent;

[0017] Preferably, the mass of the silicon carbide powder accounts for 60-90% of the mass of the main material, more preferably 75-85%, the mass of the elemental silicon powder accounts for 15-25% of the mass of the main material, more preferably 15-20%, the mass of the metal oxide accounts for 0.1-2.5% of the mass of the main material, more preferably 0.5-2%, the mass of the clay accounts for 0.1-2% of the mass of the main material, more preferably 0.5-1.5%, the mass of the binder accounts for 4-10% of the mass of the main material, more preferably 5-8%, and the mass of the pore-forming agent accounts for 2-30% of the mass of the main material, more preferably 5-15%.

[0018] In some embodiments of the present invention, the mass of the first silicon carbide powder accounts for 0% to 50% of the mass of the main material, more preferably 4 to 40%, the mass of the second silicon carbide powder accounts for 25% to 75% of the mass of the main material, more preferably 30 to 70%, and the mass of the third silicon carbide powder accounts for 0 to 5% of the mass of the main material, more preferably 1 to 4%;

[0019] Alternatively, the mass ratio of the first, second and third silicon carbide powders is (0-50):(30-75):(0-5), wherein the masses of the first and third silicon carbide powders are not zero at the same time.

[0020] In some embodiments of the present invention, the pore-forming agent is selected from at least one of polyacrylic acid, polyacrylamide, polyvinyl alcohol, polymethyl methacrylate microspheres, starch, and expanded microspheres;

[0021] And / or, the pore-forming agent has a D10 ≥ 10 μm and a D90 ≤ 35 μm.

[0022] In some embodiments of the present invention, the particle size specifications of the elemental silicon powder are D10>1 μm and D90<15 μm, the particle size specifications of the metal oxide are D10>2.8 μm and D90<8 μm, and the particle size specifications of the clay are D10>2 μm and D90<17 μm;

[0023] and / or, the binder is selected from at least one of polyvinyl alcohol, polyethylene glycol, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose;

[0024] In some embodiments of the present invention, the metal oxide is at least one selected from calcium oxide, sodium oxide, magnesium oxide, aluminum oxide, barium oxide, iron oxide, and copper oxide.

[0025] In some embodiments of the present invention, the pore density of the honeycomb ceramic substrate is 200 to 400 cpsi, preferably 275 to 305 cpsi.

[0026] In some embodiments of the present invention, the median pore diameter D50 of the honeycomb ceramic support is 10 to 30 μm, preferably 10 to 18 μm.

[0027] In some embodiments of the present invention, the pore volume of the honeycomb ceramic support is 0.18 to 0.6 mL / g, preferably 0.2 to 0.3 mL / g.

[0028] In order to achieve the above object, the present invention also provides the following technical solutions:

[0029] A method for preparing the above-mentioned honeycomb ceramic carrier comprises the following steps:

[0030] S1, providing raw materials, wherein the raw materials include silicon carbide powder, elemental silicon powder, metal oxide, clay, binder and pore former;

[0031] S2, mixing, kneading, mixing, extruding, drying, cutting, and sintering the raw materials in step S1 to obtain a ceramic unit body;

[0032] S3, sequentially subjecting the ceramic unit bodies to splicing, grinding, and skin grafting to obtain the honeycomb ceramic carrier.

[0033] In some embodiments of the present invention, the silicon carbide powder includes two or three of the following: a first silicon carbide powder having a particle size of 30 to 50 μm, a second silicon carbide powder having a particle size of 15 to 30 μm, and a third silicon carbide powder having a particle size of less than 15 μm;

[0034] Preferably, the particle size of the first silicon carbide powder is 35 to 45 μm, the particle size of the second silicon carbide powder is 20 to 30 μm, and the particle size of the third silicon carbide powder is 4 to 12 μm.

[0035] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.15-0.25):1, preferably (0.17-0.23):1;

[0036] And / or, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.4):1, preferably (0.3-0.35):1;

[0037] And / or, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.25):1, preferably (0.15-0.2):1.

[0038] In some embodiments of the present invention, in step S2, a pore plugging step is further included between sintering and drying.

[0039] In some embodiments of the present invention, in step S2, the raw materials are mixed by first dry mixing and then wet mixing;

[0040] And / or, in step S2, the drying is performed by microwave drying;

[0041] And / or, in the step S2, the sintering is performed by first sintering without oxygen and then sintering with oxygen.

[0042] In order to achieve the above object, the present invention also provides the following technical solutions:

[0043] An exhaust gas catalytic core, comprising:

[0044] The honeycomb ceramic carrier mentioned above or the honeycomb ceramic carrier made by the above method; and

[0045] The catalyst is coated on the inner wall surface of the pores of the honeycomb ceramic carrier.

[0046] Further areas of applicability will become apparent from the description provided in this disclosure.

[0047] 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.

[0048] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0049] The present invention provides a silicon carbide honeycomb ceramic structure with a special crystal phase ratio, which achieves low cost and excellent performance. That is, by using a honeycomb ceramic carrier made of 4HSiC-6HSiC with a specific crystal phase ratio, better performance is obtained, especially a thermal diffusion coefficient of 5 to 25 mm 2 / s, bringing the performance of this honeycomb ceramic substrate up to the state-of-the-art, while also achieving lower production costs due to the specific ratio of 4HSiC-6HSiC crystal phases in silicon carbide. Especially at high porosity, the honeycomb ceramic substrate provided by the present invention exhibits improved pore volume and thermal diffusivity, while offering a higher cost-performance ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some implementation plans of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0051] Figure 1 A flow chart of a method for preparing a honeycomb ceramic substrate provided in the first embodiment of the present invention;

[0052] Figure 2 XRD patterns of high-purity silicon carbide, primary silicon carbide powder, secondary silicon carbide powder, and tertiary silicon carbide powder raw materials provided in the second embodiment of the present invention;

[0053] Figure 3 These are the XRD patterns of the finished carriers of Comparative Example 1, Comparative Example 2, Example 1, Example 5, and Example 8 of the present invention. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0055] Any specific numerical value disclosed herein (including the endpoints of a numerical range) is not limited to the exact value of the numerical value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Moreover, for a disclosed numerical range, any combination of the endpoints of the range, between the endpoints and the specific points in the range, and between the specific points can be used to generate one or more new numerical ranges, and these new numerical ranges should also be considered to be specifically disclosed herein.

[0056] The terms used in this disclosure are intended only to describe specific exemplary embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used in this disclosure may be intended to also include plural forms. The terms "comprise", "include", "contain", and "have" are inclusive and therefore illustrate the presence of the features, elements, compositions, steps, integers, operations, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or their collections. Although the open-ended term "comprising" should be understood as a non-limiting term for describing and claiming the various embodiments described in this disclosure, in some aspects, the term may alternatively be understood as a more restrictive and limited term, such as "consisting of" or "substantially consisting of". Thus, for any given embodiment of a narration composition, material, component, element, feature, integer, operation, and / or process step, the disclosure also specifically includes an embodiment consisting of or substantially consisting of such a composition, material, component, element, feature, integer, operation, and / or process step. In the case of "consisting of," alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations and / or process steps, while in the case of "consisting essentially of," any additional compositions, materials, components, elements, features, integers, operations and / or process steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, features, integers, operations and / or process steps that do not materially affect the basic and novel characteristics may be included in such embodiments.

[0057] Any method steps, processes, and operations described in this disclosure are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless expressly identified as a certain order of performance. It is also to be understood that additional or alternative steps may be used unless otherwise stated.

[0058] In this application, except for the contents explicitly described, any matters or issues not mentioned are directly applicable to those known in the art without any changes. Moreover, any embodiment described in this disclosure can be freely combined with one or more other embodiments described in this disclosure, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated in this disclosure, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0059] 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.

[0060] Unless otherwise stated, when % is mentioned herein, it means wt.%.

[0061] It is worth noting that the definitions or explanations of some parameters in the specification of the present invention are as follows:

[0062] Pore ​​volume, also known as pore volume, refers to the total volume of pores per unit mass of porous solids. It is one of the important characteristic values ​​of porous structure adsorbents or catalysts. It is usually expressed as the volume of adsorbent micropores per unit weight of adsorbent, with the unit of cm3 / g.

[0063] Thermal diffusivity, commonly denoted by the symbol α, is a physical quantity that describes the ability of a material to propagate temperature. Its units are square meters per second (m² / s) and can be calculated using the formula α = λ / ρc, where λ represents thermal conductivity (W / (m·K)), ρ is density (kg / m³), and c is specific heat capacity (J / (kg·K)).11 The thermal diffusivity reflects the rate at which temperature changes propagate when a material is subjected to thermal stimulation. A larger α value indicates a greater ability for the material to equalize temperature, meaning that temperature changes propagate more rapidly within the material.

[0064] It is worth noting that, in the cumulative pore volume of the partition wall measured by the mercury intrusion method, the pore diameter at which the cumulative pore volume is 10% of the total pore volume is taken as D10, the pore diameter at which the cumulative pore volume is 50% of the total pore volume is taken as D50, that is, the median pore diameter, and the pore diameter at which the cumulative pore volume is 90% of the total pore volume is taken as D90.

[0065] In the context of this disclosure, cell density refers to the number of cells per square inch in the cross section of the honeycomb ceramic substrate, with the unit being cpsi. Cells herein include both open cells and closed cells.

[0066] First aspect

[0067] A honeycomb ceramic carrier contains silicon carbide, wherein the crystal phases of the silicon carbide include 4H-SiC and 6H-SiC, the mass of the 4H-SiC accounts for 13% to 30% of the total mass of the honeycomb ceramic carrier, the mass of the 6H-SiC accounts for 40% to 55% of the total mass of the honeycomb ceramic carrier, and the porosity of the honeycomb ceramic carrier is 45% to 70%, preferably 50% to 65%.

[0068] The honeycomb ceramic carrier provided by the present invention has a higher cost-performance ratio while ensuring better porosity, pore volume and thermal diffusion coefficient.

[0069] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC is 1:(2-4), preferably 1:2.

[0070] In some embodiments of the present invention, the honeycomb ceramic carrier further contains elemental silicon, and the mass of the elemental silicon accounts for 10-25%, preferably 15-25%, of the total mass of the honeycomb ceramic carrier.

[0071] In some embodiments of the present invention, the honeycomb ceramic support further contains silicon dioxide, and the mass of the silicon dioxide accounts for 5 to 25%, preferably 8 to 18%, of the total mass of the honeycomb ceramic support.

[0072] In some embodiments of the present invention, the thermal diffusion coefficient of the honeycomb ceramic substrate is 5 to 25 mm 2 / s, preferably 16 to 20 mm 2 / s.

[0073] In some embodiments of the present invention, the raw materials of the honeycomb ceramic carrier include main materials and auxiliary materials, wherein the main materials include two or three of the following: a first silicon carbide powder with a particle size of 30 to 50 μm, a second silicon carbide powder with a particle size of 15 to 30 μm, and a third silicon carbide powder with a particle size less than 15 μm.

[0074] In some embodiments of the present invention, the particle size of the first silicon carbide powder is 35-45 μm, the particle size of the second silicon carbide powder is 20-30 μm, and the particle size of the third silicon carbide powder is 4-12 μm.

[0075] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.15-0.25):1, preferably (0.17-0.23):1.

[0076] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.4):1, preferably (0.3-0.35):1.

[0077] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.25):1, preferably (0.15-0.2):1.

[0078] In some embodiments of the present invention, the main material further includes elemental silicon powder, metal oxides, and clay.

[0079] In some embodiments of the present invention, the auxiliary materials include a binder and a pore-forming agent.

[0080] In some embodiments of the present invention, the mass of the silicon carbide powder accounts for 60-90% of the mass of the main material, more preferably 75-85%, the mass of the elemental silicon powder accounts for 15-25% of the mass of the main material, more preferably 15-20%, the mass of the metal oxide accounts for 0.1-2.5% of the mass of the main material, more preferably 0.5-2%, the mass of the clay accounts for 0.1-2% of the mass of the main material, more preferably 0.5-1.5%, the mass of the binder accounts for 4-10% of the mass of the main material, more preferably 5-8%, and the mass of the pore-forming agent accounts for 2-30% of the mass of the main material, more preferably 5-15%. In the context of the present invention, the total mass of the main materials, i.e., the silicon carbide powder, elemental silicon powder, metal oxide, and clay, always adds up to 100%, that is, the total mass of the main materials refers to the total mass of the silicon carbide powder, elemental silicon powder, metal oxide, and clay.

[0081] In some embodiments of the present invention, the mass of the first silicon carbide powder accounts for 0% to 50% of the mass of the main material, more preferably 4 to 40%, the mass of the second silicon carbide powder accounts for 25% to 75% of the mass of the main material, more preferably 30 to 70%, and the mass of the third silicon carbide powder accounts for 0 to 5% of the mass of the main material, more preferably 1 to 4%;

[0082] Alternatively, the mass ratio of the first, second and third silicon carbide powders is (0-50):(30-75):(0-5), wherein the masses of the first and third silicon carbide powders are not zero at the same time.

[0083] In some embodiments of the present invention, the pore-forming agent is selected from at least one of polyacrylic acid, polyacrylamide, polyvinyl alcohol, polymethyl methacrylate microspheres, starch, and expanded microspheres.

[0084] In some embodiments of the present invention, the pore-forming agent has a D10 ≥ 10 μm and a D90 ≤ 35 μm.

[0085] In some embodiments of the present invention, the particle size specifications of the elemental silicon powder are D10>1 μm and D90<15 μm.

[0086] In some embodiments of the present invention, the particle size specifications of the metal oxide are D10>2.8 μm and D90<8 μm.

[0087] In some embodiments of the present invention, the particle size specifications of the clay are D10>2 μm and D90<17 μm.

[0088] In some embodiments of the present invention, the binder is selected from at least one of polyvinyl alcohol, polyethylene glycol, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose.

[0089] In some embodiments of the present invention, the metal oxide is at least one selected from calcium oxide, sodium oxide, magnesium oxide, aluminum oxide, barium oxide, iron oxide, and copper oxide.

[0090] In some embodiments of the present invention, the pore density of the honeycomb ceramic substrate is 200 to 400 cpsi, preferably 275 to 305 cpsi.

[0091] In some embodiments of the present invention, the pore size of the honeycomb ceramic support is 10 to 30 μm, preferably 10 to 18 μm.

[0092] In some other embodiments of the present invention, the porosity of the honeycomb ceramic support is 30-70%, preferably 35-60%.

[0093] In some embodiments of the present invention, the pore volume of the honeycomb ceramic support is 0.18 to 0.6 mL / g, preferably 0.2 to 0.3 mL / g.

[0094] It is worth noting that the honeycomb ceramic carrier provided by the present invention can be used as an exhaust catalytic core, and further can be used for catalytic purification of exhaust or waste gas, more specifically, it can be used for catalytic purification of waste gas generated by incomplete combustion of diesel.

[0095] In some embodiments of the present invention, the honeycomb ceramic carrier has a plurality of compartments extending along its longitudinal direction, a portion of the compartments are sealed and blocked at one end of the longitudinal direction of the honeycomb ceramic carrier, and another portion of the compartments are sealed and blocked at the other end, a partition wall is provided between the two compartments to form an adjacent wall, and a plurality of pores are provided on the partition wall for airflow exchange between the two compartments.

[0096] Second aspect

[0097] See also Figure 1 A method for preparing the above-mentioned honeycomb ceramic carrier comprises the following steps: S1, providing raw materials, wherein the raw materials include silicon carbide powder, elemental silicon powder, metal oxide, clay, binder and pore-forming agent; S2, mixing, kneading, mixing, extruding, drying, cutting and sintering the raw materials in step S1 to obtain ceramic unit bodies; S3, splicing, grinding and grafting the ceramic unit bodies in sequence to obtain the honeycomb ceramic carrier.

[0098] In some embodiments of the present invention, the silicon carbide powder includes two or three of the following: a first silicon carbide powder with a particle size of 30 to 50 μm, a second silicon carbide powder with a particle size of 15 to 30 μm, and a third silicon carbide powder with a particle size less than 15 μm.

[0099] In some embodiments of the present invention, the particle size of the first silicon carbide powder is 35-45 μm, the particle size of the second silicon carbide powder is 20-30 μm, and the particle size of the third silicon carbide powder is 4-12 μm.

[0100] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.15-0.25):1, preferably (0.17-0.23):1.

[0101] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.4):1, preferably (0.3-0.35):1.

[0102] In some embodiments of the present invention, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.25):1, preferably (0.15-0.2):1.

[0103] In some embodiments of the present invention, in step S2, a pore plugging step is further included between sintering and drying.

[0104] In some embodiments of the present invention, in step S2, the raw materials are mixed by first dry mixing and then wet mixing.

[0105] In some embodiments of the present invention, in step S2, the drying is performed by microwave drying.

[0106] In some embodiments of the present invention, in step S2, the sintering is performed by first sintering without oxygen and then sintering with oxygen.

[0107] The third aspect

[0108] An exhaust gas catalytic core comprises: the honeycomb ceramic carrier mentioned above or the honeycomb ceramic carrier prepared by the above method; and a catalyst coated on the inner wall surface of the pores of the honeycomb ceramic carrier.

[0109] It is worth noting that the exhaust catalytic core provided by the present invention can be used for catalytic purification of exhaust gas or waste gas, and more specifically can be used for catalytic purification of waste gas generated by incomplete combustion of diesel.

[0110] Example 1

[0111] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, of which the first silicon carbide powder accounts for 47wt.%, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.2:1, the second silicon carbide powder accounts for 33wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.3:1, the proportion of elemental silicon powder is 18wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.5wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 2.2wt.%; the above-mentioned binder is polyethylene glycol; the above-mentioned pore-forming agent is polyacrylic acid and starch, and the mass ratio of polyacrylic acid to starch in the pore-forming agent is 1:1; the above-mentioned metal oxide is calcium oxide.

[0112] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 45.2 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0113] Example 2

[0114] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 75wt.%, of which the first silicon carbide powder accounts for 43wt.%, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.18:1, the second silicon carbide powder accounts for 32wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.3:1, the elemental silicon powder accounts for 20.8wt.%, the clay accounts for 1.5wt.%, the metal oxide powder accounts for 2.2wt.%, the binder accounts for 6.8wt.%, and the pore-forming agent accounts for 2.2wt.%; the binder is carboxymethyl cellulose; the pore-forming agent is polylactic acid and starch, and the mass ratio of polylactic acid and starch in the pore-forming agent is 1:1; the metal oxide is sodium oxide.

[0115] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 45.2 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0116] Example 3

[0117] In this embodiment, the proportion of silicon carbide powder is 77wt.%, of which the first silicon carbide powder accounts for 38wt.%, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.17:1, the second silicon carbide powder accounts for 39wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.31:1, the proportion of elemental silicon powder is 19.8wt.%, the proportion of clay is 1.5wt.%, the proportion of the main material of metal oxide powder is 1.7wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 7wt.%; the above-mentioned binder is methyl cellulose; the above-mentioned pore-forming agent is polyvinyl butyral and starch, and the mass ratio of polyvinyl butyral and starch in the pore-forming agent is 1:1; the above-mentioned metal oxide is magnesium oxide.

[0118] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 45.2 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0119] Example 4

[0120] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, of which the proportion of the first silicon carbide powder is 35wt.%, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.16:1, the proportion of the second silicon carbide powder is 40wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.33:1, the proportion of the third silicon carbide powder is 5wt.%, the mass ratio of the third silicon carbide powder is 0.16:1, and the proportion of the second silicon carbide powder is 0.16:1. The mass ratio of 4H-SiC to 6H-SiC is 0.18:1, the proportion of elemental silicon powder is 18wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.5wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 9.3wt.%; the above-mentioned binder is ethyl cellulose; the above-mentioned pore-forming agent is polyacrylic acid, starch, and polyvinyl alcohol, and the mass ratio of polyacrylic acid, starch, and polyvinyl alcohol in the pore-forming agent is 1:1:1; the above-mentioned metal oxide is copper oxide.

[0121] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 45.5 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting to obtain a honeycomb ceramic carrier.

[0122] Example 5

[0123] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 83wt.%, of which the proportion of the first silicon carbide powder is 35wt.%, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.2:1, the proportion of the second silicon carbide powder is 45wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.36:1, the proportion of the third silicon carbide powder is 5wt.%, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is 0. The mass ratio of SiC to 6H-SiC is 0.22:1, the proportion of elemental silicon powder is 15.2wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.3wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 10.1wt.%; the above-mentioned binder is polyethylene glycol; the above-mentioned pore-forming agent is polyvinyl acetate, starch, and polyvinyl alcohol, and the mass ratio of polyvinyl acetate, starch, and polyvinyl alcohol in the pore-forming agent is 1:1:1; the above-mentioned metal oxide is iron oxide.

[0124] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 46 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting to obtain a honeycomb ceramic carrier.

[0125] Example 6

[0126] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, of which the proportion of the first silicon carbide powder is 25wt.%, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.25:1, the proportion of the second silicon carbide powder is 50wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.32:1, the proportion of the third silicon carbide powder is 5wt.%, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is 0. The mass ratio of SiC to 6H-SiC is 0.19:1, the proportion of elemental silicon powder is 18.2wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.3wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 13.5wt.%; the above-mentioned binder is polyethylene glycol; the above-mentioned pore-forming agent is polyvinyl alcohol and polymethyl methacrylate microspheres, and the mass ratio of polyvinyl alcohol and polymethyl methacrylate microspheres in the pore-forming agent is 1:1; the above-mentioned metal oxide is aluminum oxide.

[0127] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 46 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting to obtain a honeycomb ceramic carrier.

[0128] Example 7

[0129] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, of which the proportion of the first silicon carbide powder is 15wt.%, and the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.23:1. The proportion of the second silicon carbide powder is 60wt.%, and the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.38:1. The proportion of the third silicon carbide powder is 5wt.%, and the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is 0. -SiC and 6H-SiC have a mass ratio of 0.13:1, the proportion of elemental silicon powder is 18wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.5wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 17.6wt.%; the above-mentioned binder is ethyl cellulose; the above-mentioned pore-forming agent is polyvinyl alcohol and polymethyl methacrylate microspheres, and the mass ratio of polyvinyl alcohol and polymethyl methacrylate microspheres in the pore-forming agent is 1:1; the above-mentioned metal oxide is calcium oxide.

[0130] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 46.5 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting to obtain a honeycomb ceramic carrier.

[0131] Example 8

[0132] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, of which the proportion of the first silicon carbide powder is 5wt.%, the mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is 0.25:1, the proportion of the second silicon carbide powder is 70wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.3:1, the proportion of the third silicon carbide powder is 5wt.%, the mass ratio of the third silicon carbide powder is 0. The mass ratio of 4H-SiC to 6H-SiC is 0.25:1, the proportion of elemental silicon powder is 18wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.5wt.%, the proportion of binder is 2wt.%, and the proportion of pore-forming agent is 22.7wt.%; the above-mentioned binder is ethyl cellulose; the above-mentioned pore-forming agent is polyacrylic acid, polyacrylamide, and starch, and the mass ratio of polyacrylic acid, polyacrylamide, and starch in the pore-forming agent is 1:1; the above-mentioned metal oxide is barium oxide.

[0133] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 46.8 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0134] Example 9

[0135] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, excluding the first silicon carbide powder, the proportion of the second silicon carbide powder is 75wt.%, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is 0.4:1, the proportion of the third silicon carbide powder is 5wt.%, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is 0.15:1, the proportion of elemental silicon powder is 17.8wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.7wt.%, the proportion of binder is 2wt.%, and the proportion of pore-forming agent is 23.23wt.%; the above-mentioned binder is methyl cellulose; the above-mentioned pore-forming agent is polyacrylic acid, starch, and polyacrylamide, and the mass ratio of polyacrylic acid, starch, and polyacrylamide in the pore-forming agent is 1:1:1; the above-mentioned metal oxide is sodium oxide.

[0136] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 46.8 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0137] Comparative Example 1

[0138] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, high-purity silicon carbide powder with a single particle size is used, and the particle size of the silicon carbide powder is 30.3μm. The mass ratio of 4H-SiC to 6H-SiC in the high-purity silicon carbide powder is 0.05:1, the proportion of elemental silicon powder is 18wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.5wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 3wt.%; the above-mentioned binder is ethyl cellulose; the above-mentioned pore-forming agent is polyacrylic acid and starch, and the mass ratio of polyacrylic acid and starch in the pore-forming agent is 1:1; the above-mentioned metal oxide is aluminum oxide.

[0139] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 45.2 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0140] Comparative Example 2

[0141] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, high-purity silicon carbide powder with a single particle size is used, and the particle size of the silicon carbide powder is 30.1μm. The mass ratio of 4H-SiC to 6H-SiC in the high-purity silicon carbide powder is 0.03:1, the proportion of elemental silicon powder is 18wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.5wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 2.8wt.%; the above-mentioned binder is carboxymethyl cellulose; the above-mentioned pore-forming agent is polyacrylic acid and starch, and the mass ratio of polyacrylic acid and starch in the pore-forming agent is 1:1; the above-mentioned metal oxide is magnesium oxide.

[0142] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 45.2 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0143] Comparative Example 3

[0144] In this embodiment, relative to the main material, the proportion of silicon carbide powder is 80wt.%, high-purity silicon carbide powder of a single particle size is used, and the particle size of the silicon carbide powder is 30.5μm. The mass ratio of 4H-SiC to 6H-SiC in the high-purity silicon carbide powder is 0.05:1, the proportion of elemental silicon powder is 18wt.%, the proportion of clay is 0.5wt.%, the proportion of metal oxide powder is 1.5wt.%, the proportion of binder is 6.8wt.%, and the proportion of pore-forming agent is 23wt.%; the above-mentioned binder is glycerol; the above-mentioned pore-forming agent is polyacrylic acid, polyacrylamide and starch, and the mass ratio of polyacrylic acid, polyacrylamide and starch in the pore-forming agent is 1:1; the above-mentioned metal oxide is barium oxide

[0145] All the above raw materials are added to a plowshare mixer for dry mixing, wherein the dry mixing time is 15 minutes and the dry mixing speed is 95 rpm; after the dry mixing is completed, water is added for wet mixing, wherein the proportion of water relative to the main material is 45.2 wt.%, the wet mixing time is 5 minutes, and the wet mixing speed is 95 rpm; after the wet mixing is completed, the obtained mixture is put into a biaxial kneader for kneading, and the kneading time is 60 minutes; after the kneading is completed, the mud is kneaded, and after the mud kneading is completed, it is put into the extruder to extrude to obtain a unit body; the unit body is sequentially subjected to microwave drying, pore plugging, degreasing, oxygen-free sintering, and oxidation sintering, and then splicing, skin grinding, and skin grafting are performed in sequence to obtain a honeycomb ceramic carrier.

[0146] Comparative Examples 1 and 2, relative to Example 1, used high-purity silicon carbide powder of a single particle size, and the mass ratio of 4H-SiC to 6H-SiC in the powder was less than 0.1:1. Comparative Example 3, relative to Example 9, used high-purity silicon carbide powder of a single particle size, and the mass ratio of 4H-SiC to 6H-SiC in the powder was less than 0.1:1.

[0147] The particle size ratios of the silicon carbide powders in the above-mentioned embodiments and comparative examples are shown in Table 1 below.

[0148] Table 1 Partial formulations of various embodiments and comparative examples

[0149]

[0150]

[0151] Table 2 below shows the product properties of each embodiment and comparative example. Each group of crystal phases was analyzed by XRD (X-ray diffraction analyzer), using a JS / YQXRD-201 model with a scanning angle range of 10° to 80°, a scanning speed of 0.2 s / step, and a scanning step of 0.02° / step. The median pore size, average pore size, porosity, and pore volume were measured using mercury intrusion porosimetry, using a mercury intrusion porosimeter (MicroActive AutoPore V9600 Version 2.03.00) produced by Micromeritics (USA). The test method complies with the national standard: GB / T 21650.1-2008. The thermal diffusivity test method is a laser thermal conductivity meter. A sample with a side length of 10mm*10mm and a thickness of 1mm is cut and measured using a German NETZSCH laser thermal conductivity meter (LFA467) at a heating interval of 50k / min. The test method is in accordance with the national standard: GB / T22588-2008.

[0152] Table 2 Honeycomb ceramic substrate properties of various embodiments and comparative examples

[0153]

[0154] It is worth noting that during the preparation process, 6H-SiC will be transformed into SiO2 and CO2. At this time, the content of 6H-SiC crystal phase will decrease, and the SiO2 content will increase, resulting in an increase in the ratio of 4H-SiC to 6H-SiC.

[0155] In comparison, Examples 1 to 9 are made of SiC powder with a low cost and special crystal phase ratio. Among them, Example 1 has similar performance data such as thermal diffusion coefficient, porosity, and pore volume as those of Comparative Examples 1 and 2. Compared with Comparative Example 3, Examples 8 and 9 have higher thermal diffusion coefficients at high porosity. This shows that the SiC powder with a low cost and special crystal phase ratio used in the present invention is beneficial for preparing a honeycomb ceramic carrier with various properties similar to those of high-purity SiC honeycomb ceramics without reducing product performance, and has a special crystal phase ratio, wherein the crystal phase ratio of 4H to 6H is 0.25 to 0.5; and under high porosity, the honeycomb ceramic carrier of the present invention has higher thermal conductivity.

[0156] See also Figure 2 , Figure 2From top to bottom, they are the XRD patterns of high-purity silicon carbide (1), silicon carbide primary powder (2), silicon carbide secondary powder (3), and silicon carbide tertiary powder (4). It can be seen from the figure that the four SiC raw materials are composed of 4H-SiC and 6H-SiC crystal phases, among which there are 6 main peaks representing 6H-SiC crystal phase. The two main peaks represent the 4H-SiC crystal phase 4H-SiC is a hexagonal silicon carbide with a stacking sequence of four repeating layers along the c-axis in its crystal structure, and its basic stacking sequence is ABAC...; 6H-SiC is a hexagonal silicon carbide with a stacking sequence of six repeating layers along the c-axis in its crystal structure, and its basic stacking sequence is ABCACB...; wherein, each group of crystal phases was analyzed by X-ray diffraction analyzer (JS / YQXRD-201), with a scanning angle range of 10° to 80°, a scanning speed of 0.2 s / step, and a scanning step of 0.02° / step; the semi-quantitative analysis method of XRD is in accordance with GB_T42676-2023.

[0157] It can be seen that the mass ratio of 4H-SiC to 6H-SiC in the high-purity silicon carbide powder raw material is 0.05, the mass ratio of 6H-SiC exceeds 90%, and the peak value of 4H-SiC is significantly lower than that of the other three raw materials. Figure 2 The mass ratio of 4H-SiC to 6H-SiC in the primary silicon carbide powder is 0.19, of which the elemental silicon powder accounts for 0.1%. The mass ratio of 4H-SiC to 6H-SiC in the secondary silicon carbide powder is 0.36, of which the elemental silicon powder accounts for 0.2%. The mass ratio of 4H-SiC to 6H-SiC in the tertiary silicon carbide powder is 0.19, of which the elemental silicon powder accounts for 0.58%.

[0158] See also Figure 3 , Figure 3 The XRD patterns of the finished carriers of Comparative Example 1 (5), Comparative Example 2 (6), Example 1 (7), Example 5 (8), and Example 8 (9) are shown from top to bottom. It can be seen from the XRD patterns of each product that the finished products obtained in the above-mentioned embodiments and comparative examples, i.e., the honeycomb ceramic carriers, contain four crystal phases in total: 4H-SiC(◆) and The peak value of 4H-SiC in the comparative example is significantly lower; among them, the mass ratio of 4H-SiC to 6H-SiC in comparative example 1 (10) is 0.072, the mass ratio of 4H-SiC to 6H-SiC in comparative example 2 (11) is 0.067, the mass ratio of 4H-SiC to 6H-SiC in embodiment 1 (12) is 0.412, the mass ratio of 4H-SiC to 6H-SiC in embodiment 5 (13) is 0.279, and the mass ratio of 4H-SiC to 6H-SiC in embodiment 8 (14) is 0.395. It can be seen that the crystal phase peak value of 4H-SiC in the comparative example is significantly lower or even tends to be stable, and the peak value of 6H-SiC is higher, while the crystal phase peak value of 4H-SiC in the embodiment is higher, and the peak value of 6H-SiC is lower than that of the comparative example.

[0159] The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims. In addition, the principle and implementation of the present invention are explained in detail in the specification using specific examples. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. The content of this specification should not be understood as limiting the present invention.

Claims

1. A honeycomb ceramic substrate, characterized in that: The honeycomb ceramic carrier contains silicon carbide, the crystal phase of the silicon carbide includes 4H-SiC and 6H-SiC, the mass of the 4H-SiC accounts for 13% to 30% of the total mass of the honeycomb ceramic carrier, the mass of the 6H-SiC accounts for 40% to 55% of the total mass of the honeycomb ceramic carrier, and the porosity of the honeycomb ceramic carrier is 45% to 70%; The thermal diffusion coefficient of the honeycomb ceramic carrier is 5 to 25 mm 2 / s; The raw materials of the honeycomb ceramic carrier include a main material, wherein the main material includes two or three of the following: a first silicon carbide powder with a particle size of 30 to 50 μm, a second silicon carbide powder with a particle size of 15 to 30 μm, and a third silicon carbide powder with a particle size of less than 15 μm; in, The mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.15-0.25):1; and / or, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.4):1; And / or, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.25):1; The mass ratio of the first, second and third silicon carbide powders is (0-50):(30-75):(0-5), wherein the masses of the first and third silicon carbide powders are not zero at the same time.

2. The honeycomb ceramic carrier according to claim 1, characterized in that The porosity of the honeycomb ceramic carrier is 50-65%.

3. The honeycomb ceramic carrier according to claim 1, characterized in that The mass ratio of the 4H-SiC to the 6H-SiC is 1:(2-4).

4. The honeycomb ceramic carrier according to claim 1, characterized in that The mass ratio of the 4H-SiC to the 6H-SiC is 1:

2.

5. The honeycomb ceramic carrier according to claim 1, characterized in that The honeycomb ceramic carrier further contains elemental silicon, and the mass of the elemental silicon accounts for 10 to 25% of the total mass of the honeycomb ceramic carrier; And / or, the honeycomb ceramic support further contains silicon dioxide, and the mass of the silicon dioxide accounts for 5 to 25% of the total mass of the honeycomb ceramic support.

6. The honeycomb ceramic carrier according to claim 1, characterized in that The honeycomb ceramic carrier further contains elemental silicon, and the mass of the elemental silicon accounts for 15 to 25% of the total mass of the honeycomb ceramic carrier; And / or, the honeycomb ceramic support further contains silicon dioxide, and the mass of the silicon dioxide accounts for 8 to 18% of the total mass of the honeycomb ceramic support.

7. The honeycomb ceramic carrier according to claim 1, characterized in that: The thermal diffusion coefficient of the honeycomb ceramic carrier is 16 to 20 mm 2 / s.

8. The honeycomb ceramic carrier according to claim 1, characterized in that: The particle size of the first silicon carbide powder is 35 to 45 μm, the particle size of the second silicon carbide powder is 20 to 30 μm, and the particle size of the third silicon carbide powder is 4 to 12 μm.

9. The honeycomb ceramic carrier according to claim 1, characterized in that: The mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.17-0.23):1; and / or, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.35):1; And / or, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.2):

1.

10. The honeycomb ceramic carrier according to claim 1, characterized in that The main material further comprises elemental silicon powder, metal oxide, and clay, and the raw materials of the honeycomb ceramic carrier further comprise auxiliary materials, which comprise a binder and a pore-forming agent.

11. The honeycomb ceramic carrier according to claim 10, characterized in that: The mass of the silicon carbide powder accounts for 60-90% of the mass of the main material, the mass of the elemental silicon powder accounts for 15-25% of the mass of the main material, the mass of the metal oxide accounts for 0.1-2.5% of the mass of the main material, the mass of the clay accounts for 0.1-2% of the mass of the main material, the mass of the binder accounts for 4-10% of the mass of the main material, and the mass of the pore-forming agent accounts for 2-30% of the mass of the main material.

12. The honeycomb ceramic carrier according to claim 10, characterized in that: The mass of the silicon carbide powder accounts for 75-85% of the mass of the main material, the mass of the elemental silicon powder accounts for 15-20% of the mass of the main material, the mass of the metal oxide accounts for 0.5-2% of the mass of the main material, the mass of the clay accounts for 0.5-1.5% of the mass of the main material, the mass of the binder accounts for 5-8% of the mass of the main material, and the mass of the pore-forming agent accounts for 5-15% of the mass of the main material.

13. The honeycomb ceramic carrier according to claim 10, characterized in that: The pore-forming agent is selected from at least one of polyacrylic acid, polyacrylamide, polyvinyl alcohol, polymethyl methacrylate microspheres, starch, and expanded microspheres; And / or, the pore-forming agent has a D10 ≥ 10 μm and a D90 ≤ 35 μm.

14. The honeycomb ceramic carrier according to claim 10, characterized in that: The particle size specifications of the elemental silicon powder are D10>1μm and D90<15μm, the particle size specifications of the metal oxide are D10>2.8μm and D90<8μm, and the particle size specifications of the clay are D10>2μm and D90<17μm; and / or, the binder is selected from at least one of polyvinyl alcohol, polyethylene glycol, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose; And / or, the metal oxide is at least one selected from calcium oxide, sodium oxide, magnesium oxide, aluminum oxide, barium oxide, iron oxide, and copper oxide.

15. The honeycomb ceramic support according to any one of claims 1 to 14, characterized in that: The pore density of the honeycomb ceramic carrier is 200-400 cpsi.

16. The honeycomb ceramic support according to any one of claims 1 to 14, characterized in that: The pore density of the honeycomb ceramic carrier is 275 to 305 cpsi.

17. The honeycomb ceramic support according to any one of claims 1 to 14, characterized in that: The median pore diameter D50 of the honeycomb ceramic carrier is 10 to 30 μm.

18. The honeycomb ceramic support according to any one of claims 1 to 14, characterized in that The median pore diameter D50 of the honeycomb ceramic carrier is 10 to 18 μm.

19. The honeycomb ceramic support according to any one of claims 1 to 14, characterized in that: The pore volume of the honeycomb ceramic carrier is 0.18-0.6 mL / g.

20. The honeycomb ceramic support according to any one of claims 1 to 14, characterized in that The pore volume of the honeycomb ceramic carrier is 0.2-0.3 mL / g.

21. A method for preparing the honeycomb ceramic support according to any one of claims 1 to 20, characterized in that: The method comprises the following steps: S1, providing raw materials, wherein the raw materials include silicon carbide powder, elemental silicon powder, metal oxide, clay, binder and pore former; S2, mixing, kneading, mixing, extruding, drying, cutting, and sintering the raw materials in step S1 to obtain a ceramic unit body; S3, sequentially subjecting the ceramic unit bodies to splicing, grinding, and skin grafting to obtain the honeycomb ceramic carrier.

22. The method according to claim 21, characterized in that The silicon carbide powder includes two or three of the following: a first silicon carbide powder with a particle size of 30 to 50 μm, a second silicon carbide powder with a particle size of 15 to 30 μm, and a third silicon carbide powder with a particle size less than 15 μm.

23. The method according to claim 22, characterized in that The particle size of the first silicon carbide powder is 35 to 45 μm, the particle size of the second silicon carbide powder is 20 to 30 μm, and the particle size of the third silicon carbide powder is 4 to 12 μm.

24. The method according to claim 22, characterized in that The mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.15-0.25): 1; and / or, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.4):1; And / or, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.25):

1.

25. The method according to claim 22, wherein The mass ratio of 4H-SiC to 6H-SiC in the first silicon carbide powder is (0.17-0.23):1; and / or, the mass ratio of 4H-SiC to 6H-SiC in the second silicon carbide powder is (0.3-0.35):1; And / or, the mass ratio of 4H-SiC to 6H-SiC in the third silicon carbide powder is (0.15-0.2):

1.

26. The method according to any one of claims 21 to 25, characterized in that In the step S2, there is also a pore plugging step between sintering and drying.

27. The method according to any one of claims 21 to 25, characterized in that In step S2, the raw materials are mixed by first dry mixing and then wet mixing; And / or, in step S2, the drying is performed by microwave drying; And / or, in the step S2, the sintering is performed by first sintering without oxygen and then sintering with oxygen.

28. An exhaust gas catalytic core, characterized in that: The exhaust gas catalytic core comprises: The honeycomb ceramic support according to any one of claims 1 to 20 or the honeycomb ceramic support prepared by the method according to any one of claims 21 to 27; and The catalyst is coated on the inner wall surface of the pores of the honeycomb ceramic carrier.

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