Preparation method of gradient honeycomb hole structure SiC catalytic membrane
A gradient honeycomb pore structure SiC catalytic membrane was prepared by 3D printing and chemical etching, which solved the clogging problem of traditional SiC catalytic membranes under high dust flue gas conditions, and achieved high flux and high catalytic activity, making it suitable for deep purification of high temperature flue gas.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2026-04-30
- Publication Date
- 2026-06-09
AI Technical Summary
Traditional homogeneous honeycomb SiC catalytic membranes are prone to clogging under high dust load flue gas conditions, leading to a rapid increase in pressure drop and flux decay, and it is difficult to achieve uniform integration of catalytic function and efficient exposure of active sites.
A gradient honeycomb pore structure SiC catalytic film was prepared by using programmable 3D printing technology combined with chemical etching. The uniform integration of catalytic components was achieved by layer-by-layer exposure curing and high-temperature sintering, and the catalytic active sites were optimized by chemical etching.
It significantly improves the flux stability and catalytic activity of the membrane, and can simultaneously retain dust and degrade nitrogen oxides and volatile organic compounds, making it suitable for the deep purification of high-temperature flue gas.
Smart Images
Figure CN122164386A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of inorganic separation membrane and catalytic material technology, specifically relating to a silicon carbide (SiC) porous catalytic membrane for high-temperature gas purification and its preparation method, particularly relating to a method for preparing a SiC catalytic membrane with a gradient honeycomb pore structure. Background Technology
[0002] High-temperature industrial flue gas (such as that from steel, cement, glass, and waste incineration processes) typically contains multiple pollutants, including dust, nitrogen oxides (NOx), and volatile organic compounds (VOCs). The efficient and synergistic removal of these pollutants is a key challenge in air pollution control. Ceramic membrane filtration coupled with catalytic oxidation technology, which loads catalytically active components onto a porous ceramic filter to simultaneously complete particulate matter filtration and gaseous pollutant catalytic degradation within a single device, is considered a highly promising solution. Among these technologies, SiC ceramics, due to their excellent high-temperature stability, high thermal conductivity, outstanding mechanical strength, and good chemical inertness, have become one of the most ideal carrier materials for this application.
[0003] Currently, traditional extrusion molding of SiC porous ceramics has significant limitations. Traditional honeycomb ceramics typically have a uniform parallel channel structure. When treating high-dust flue gas, the pressure drop at the channel inlet is prone to rapid dust bridging and blockage, leading to a sharp increase in filtration efficiency and requiring frequent backflushing and regeneration, affecting the continuity and economy of system operation. To improve anti-clogging performance, researchers have attempted to prepare porous ceramics with gradient pore sizes, such as by stacking multiple layers of pore-forming agents with different particle sizes or by using centrifugal molding. However, these traditional methods struggle to precisely control the continuity and complexity of gradient changes, and interface defects easily arise between layers due to shrinkage mismatch, affecting overall strength.
[0004] Photopolymerization 3D printing technology has provided a revolutionary means for fabricating ceramic components with complex three-dimensional structures. This technology can precisely mold arbitrarily designed structures based on digital models, including periodic minimal curved surface structures (such as Gyroid and diamond structures) that are impossible to achieve using traditional methods. It has been used to fabricate high-throughput, low-torsion SiC films (such as CN119161204A). However, existing research has largely focused on using this technology to fabricate carriers with uniform structures or periodic topology optimization. There are few systematic reports on the design and fabrication of "function-oriented" gradient structures (such as honeycomb structures with continuously varying pore size and wall thickness) designed to actively manage flow fields and achieve dust gradient interception to optimize filtration performance.
[0005] Furthermore, the effective integration of catalytic functions presents another major challenge. While co-sintering can introduce catalytic components in a single step, the components may react with SiC or undergo over-sintering at high temperatures, leading to a decrease in activity. Subsequent acid etching (such as CN115448726B) can effectively enhance catalytic activity, but how to combine this post-processing with the fabrication of precise three-dimensional gradient structures, ensuring that the etching process does not damage the carefully designed fine structure while maximizing the exposure of catalytic sites, remains an unsolved technical problem.
[0006] Therefore, there is an urgent need in the field for a preparation method that can systematically integrate customizable three-dimensional gradient structure design, uniform integration and robust immobilization of catalytic components, and post-treatment activity enhancement for catalysis, in order to develop a new generation of SiC catalytic membranes with excellent anti-clogging performance, high throughput, high catalytic activity and long lifespan, to meet the stringent requirements of deep purification of multiple pollutants in high-temperature industrial flue gas. Summary of the Invention
[0007] The purpose of this invention is to provide a method for preparing a gradient honeycomb pore structure SiC catalytic membrane. This method addresses the challenges of conventional homogeneous honeycomb or uniform three-dimensional porous SiC catalytic membranes, which are prone to clogging at the inlet end when exposed to high dust load flue gas, leading to a rapid increase in pressure drop and rapid flux decay. It also addresses the difficulty of conventional preparation methods in systematically combining the three key requirements of "anti-clogging structural design," "integrated catalytic function," and "efficient exposure of active sites." By utilizing programmable 3D printing technology, the method achieves precise gradient design of the SiC catalytic membrane pore structure as needed, thereby optimizing the internal flow field and dust distribution. This significantly improves the membrane's flux stability while maintaining high catalytic activity.
[0008] The technical solution of the present invention is as follows: A method for preparing a SiC catalytic film with a gradient honeycomb pore structure, characterized by comprising the following steps: A. SiC powder, catalytically active components, photosensitive resin monomers, photoinitiators and rheology modifiers are mixed in a predetermined ratio, and dispersed by ball milling and vacuum rotary degassing to obtain a uniform ceramic slurry suitable for photocuring. B. The ceramic slurry is introduced into a photopolymerization 3D printing device, and a ceramic film green body is formed by a layer-by-layer exposure curing process according to the preset gradient structure three-dimensional model. The gradient structure is manifested as the pore size and pore wall thickness of the honeycomb channels changing regularly along the spatial dimension. C. The green body is subjected to thermal decomposition and high-temperature sintering in sequence to obtain a SiC ceramic film with a gradient honeycomb pore structure; D. The SiC ceramic film is subjected to chemical etching to selectively modify some substances, expose and optimize catalytic active sites, and then dried to obtain the gradient honeycomb pore structure SiC catalytic film.
[0009] Preferably, the SiC powder has a particle size of 5-25 μm and a content of 40-55 wt% of the ceramic slurry; the catalytically active component is cobalt trioxide (Co2O3) with a particle size of 0.5-20 μm and a content of 1-10 wt% of the ceramic slurry; the photosensitive resin is trimethylolpropane triacrylate (TMPTA) with a content of 37-57 wt% of the ceramic slurry; the auxiliary additives are BYK P104S dispersant and BYK 045 defoamer, each with a content of 0.5-2 wt% of the ceramic slurry; and the photoinitiator is 814 photoinitiator and 789 photoinitiator, each with a content of 0.5-2 wt% of the ceramic slurry.
[0010] Preferably, the ball milling speed is 400~600 rpm and the mixing time is 3~7 h; the SiC slurry degassing speed is 1500~2500 rpm and the degassing time is 1~2 h.
[0011] Preferably, the size of the gradient honeycomb structure support unit is 1.0~2.0 mm, the wall thickness of the inlet unit is 0.1~0.5 mm, the wall thickness of the outlet unit is 0.4~0.8 mm, and the thickness of the separation layer is 50~200 μm.
[0012] Preferably, the slice thickness is 25~75 μm and the exposure intensity is 200~500 mJ / cm2.
[0013] Preferably, the temperature of the debinding process is 700~900 ℃, the heating rate is 1~2.5 ℃ / min, and the holding time is 3~5 h; the temperature of the sintering process is 1200~1500 ℃, the heating rate is 1~2.5 ℃ / min, and the holding time is 3~5 h.
[0014] Preferably, the chemical etching solution is a nitric acid solution with an acid concentration of 1-4 mol / L, an immersion time of 2-5 h, a drying temperature of 100-120 ℃, and a drying time of 8-12 h.
[0015] The gradient honeycomb pore structure SiC catalytic membrane of the present invention can be used for the in-depth treatment of pollutants in industrial exhaust gas.
[0016] The beneficial effects of this invention are: 1. By utilizing photopolymerization 3D printing technology, complex gradient structure digital models can be precisely materialized, a feat impossible with traditional extrusion and injection molding processes. The gradient honeycomb pore structure endows the catalytic membrane with higher stable flux and longer continuous operating cycles.
[0017] 2. This method achieves integrated preparation of the entire process, from "structural design to catalytic component addition, molding, sintering, and activation," resulting in a simple and controllable process. The catalytic component is uniformly introduced during the slurry stage and firmly bonded through co-sintering, avoiding common problems in subsequent loading processes such as uneven coating and easy detachment.
[0018] 3. Building upon a robust gradient support, the innovative post-chemical etching process goes beyond simple cleaning; it activates the catalytic phase. This step selectively modifies the catalytic material, creating abundant surface defects and nanostructures, significantly increasing the number and accessibility of active sites. Consequently, the catalytic membrane maintains excellent filtration performance while possessing high catalytic activity comparable to powdered catalysts.
[0019] 4. The prepared SiC catalytic membrane can simultaneously trap dust and degrade nitrogen oxides and VOCs, making it particularly suitable for the deep, efficient, and long-term treatment of high-temperature flue gas in highly polluting industries such as steel, cement, and waste incineration, and it has broad prospects for industrial application. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the support structure of the gradient honeycomb pore structure catalytic membrane material prepared in Example 3.
[0021] Figure 2 This is a cross-sectional SEM image of the gradient honeycomb pore structure catalytic membrane material prepared in Example 3.
[0022] Figure 3 This is a SEM image of the gradient honeycomb pore structure catalytic membrane material prepared in Example 3.
[0023] Figure 4 This is a pore size distribution diagram of the gradient honeycomb pore structure catalytic membrane material prepared in Example 3.
[0024] Figure 5 The graph shows the NO oxidation performance of the gradient honeycomb pore structure catalytic membrane material prepared in Example 3. Detailed Implementation
[0025] The present invention will be further explained in detail below with reference to the embodiments. The following embodiments are only for illustrating the present invention, but the implementation of the present invention is not limited thereto. Example 1
[0026] A method for preparing a SiC catalytic membrane with a gradient honeycomb pore structure, the specific steps of which are as follows: Preparation of ceramic slurry: SiC powder with a particle size of 5 μm was selected, with a content of 40 wt% of the ceramic slurry; Co2O3 with a particle size of 0.5 μm was selected, with a content of 1 wt% of the ceramic slurry; TMPTA was selected, with a content of 57 wt% of the ceramic slurry; BYK P104S dispersant and BYK 045 defoamer were each selected, with a content of 0.5 wt% of the ceramic slurry; 814 photoinitiator and 789 photoinitiator were each selected, with a content of 0.5 wt% of the ceramic slurry. The above materials were ball-milled at 400 rpm for 3 h, and then degassed and rotated at 1500 rpm for 1 h to obtain the ceramic slurry.
[0027] The ceramic slurry was introduced into a photopolymerization 3D printing device. A gradient honeycomb structure was constructed using 3D modeling software, with a support unit size of 1.0 mm, an inlet unit wall thickness of 0.1 mm, an outlet unit wall thickness of 0.4 mm, a separation layer thickness of 50 μm, a slice thickness of 25 μm, and an exposure intensity of 200 mJ / cm². Subsequently, the temperature was increased to 700 °C at a rate of 1 °C / min in air and held for 3 h to complete the slurry removal. Then, the temperature was increased to 1200 °C at a rate of 1 °C / min and held for 3 h to complete sintering. Finally, the slurry was impregnated with a 1 mol / L nitric acid solution for 2 h and dried at 100 °C for 8 h. The prepared SiC catalyst membrane had an average pore size of 1.8 μm and a gas permeability of 270 m³ / (m²•h•kPa). Example 2
[0028] A method for preparing a SiC catalytic membrane with a gradient honeycomb pore structure, the specific steps of which are as follows: Preparation of ceramic slurry: SiC powder with a particle size of 25 μm was selected, with a content of 45 wt% of the ceramic slurry; Co2O3 with a particle size of 20 μm was selected, with a content of 10 wt% of the ceramic slurry; TMPTA was selected, with a content of 37 wt% of the ceramic slurry; BYK P104S dispersant and BYK 045 defoamer were each selected, with a content of 2 wt% of the ceramic slurry; 814 photoinitiator and 789 photoinitiator were each selected, with a content of 2 wt% of the ceramic slurry. The above materials were ball-milled at 600 rpm for 7 h, and then degassed and rotated at 2500 rpm for 2 h to obtain the ceramic slurry.
[0029] The ceramic slurry was introduced into a photopolymerization 3D printing device. A gradient honeycomb structure was constructed using 3D modeling software, with a support unit size of 2.0 mm, an inlet unit wall thickness of 0.5 mm, an outlet unit wall thickness of 0.8 mm, a separation layer thickness of 200 μm, a slice thickness of 75 μm, and an exposure intensity of 500 mJ / cm². Subsequently, the temperature was increased to 900 °C at a rate of 2.5 °C / min in air and held for 5 h to complete sintering. Then, the temperature was increased to 1500 °C at a rate of 2.5 °C / min and held for 5 h to complete sintering. Finally, the sample was impregnated with a 4 mol / L nitric acid solution for 5 h and dried at 120 °C for 12 h. The prepared SiC catalyst membrane had an average pore size of 9.7 μm and a gas permeability of 780 m³ / (m²•h•kPa). Example 3
[0030] A method for preparing a SiC catalytic membrane with a gradient honeycomb pore structure, the specific steps of which are as follows: Preparation of ceramic slurry: SiC powder with a particle size of 10 μm was selected, with a content of 55 wt% of the ceramic slurry; Co2O3 with a particle size of 5 μm was selected, with a content of 2 wt% of the ceramic slurry; TMPTA was selected, with a content of 39 wt% of the ceramic slurry; BYK P104S dispersant and BYK 045 defoamer were each selected, with a content of 1 wt% of the ceramic slurry; 814 photoinitiator and 789 photoinitiator were each selected, with a content of 1 wt% of the ceramic slurry. The above materials were ball-milled at 500 rpm for 5 h, and then degassed and rotated at 2000 rpm for 1.5 h to obtain the ceramic slurry.
[0031] The ceramic slurry was introduced into a photopolymerization 3D printing device. A gradient honeycomb structure was constructed using 3D modeling software, with a support unit size of 1.5 mm, an inlet unit wall thickness of 0.3 mm, an outlet unit wall thickness of 0.6 mm, a separation layer thickness of 100 μm, a slice thickness of 50 μm, and an exposure intensity of 300 mJ / cm². Subsequently, the temperature was increased to 800 °C at a rate of 1.5 °C / min in air and held for 4 h to complete sintering. Then, the temperature was increased to 1300 °C at a rate of 1.5 °C / min and held for 4 h to complete sintering. Finally, the sample was impregnated with a 2 mol / L nitric acid solution for 3 h and dried at 110 °C for 10 h. The prepared SiC catalyst membrane had an average pore size of 4.1 μm and a gas permeability of 520 m³ / (m²•h•kPa).
[0032] Figure 1 This is a schematic diagram of the support for the gradient honeycomb pore structure SiC catalytic membrane prepared in this embodiment. Figure 2This is the cross-sectional microstructure of the gradient honeycomb pore structure SiC catalytic membrane prepared in this embodiment. The ceramic membrane separation layer is about 100 μm thick, the inlet unit wall thickness is 0.3 mm, and the outlet unit wall thickness is 0.6 mm, which is consistent with the parameters of the digital model. The microstructure has high forming accuracy, no deformation after sintering, and good strength. Figure 3 This shows the microstructure of the gradient honeycomb pore structure SiC catalytic membrane prepared in this embodiment. The neck adhesion of the SiC membrane material did not change significantly after acid etching, indicating that the acid solution only etched the fine Co2SiO4 particles on the surface of the SiC particles, shaping them into small-diameter Co3O4 particles, thereby improving the catalytic performance of the membrane material. Figure 4 This is a pore size distribution diagram of the gradient honeycomb structure SiC catalytic membrane prepared in this embodiment. The pore size distribution is well concentrated, with the main pore size around 4.1 μm. Example 4
[0033] A method for preparing a SiC catalytic membrane with a gradient honeycomb pore structure, the specific steps of which are as follows: Preparation of ceramic slurry: SiC powder with a particle size of 10 μm was selected, with a content of 55 wt% of the ceramic slurry; Co2O3 with a particle size of 5 μm was selected, with a content of 2 wt% of the ceramic slurry; TMPTA was selected, with a content of 39 wt% of the ceramic slurry; BYK P104S dispersant and BYK 045 defoamer were each selected, with a content of 1 wt% of the ceramic slurry; 814 photoinitiator and 789 photoinitiator were each selected, with a content of 1 wt% of the ceramic slurry. The above materials were ball-milled at 500 rpm for 5 h, and then degassed and rotated at 2000 rpm for 1.5 h to obtain the ceramic slurry.
[0034] The ceramic slurry was introduced into a photopolymerization 3D printing device. A gradient honeycomb structure was constructed using 3D modeling software, with a support unit size of 1.2 mm, an inlet unit wall thickness of 0.2 mm, an outlet unit wall thickness of 0.5 mm, a separation layer thickness of 100 μm, a slice thickness of 25 μm, and an exposure intensity of 200 mJ / cm². Subsequently, the temperature was increased to 800 °C at a rate of 2 °C / min in air and held for 4 h to complete sintering. Then, the temperature was increased to 1300 °C at a rate of 2 °C / min and held for 4 h to complete sintering. Finally, the sample was impregnated with a 3 mol / L nitric acid solution for 4 h and dried at 120 °C for 10 h. The prepared SiC catalyst membrane had an average pore size of 4.4 μm and a gas permeability of 490 m³ / (m²•h•kPa). Example 5
[0035] The performance testing steps for SiC catalytic films with gradient honeycomb pore structure are as follows: The catalytic membrane prepared in Example 3 was placed in a test fixture. The test conditions were: an inlet gas rate of 250 mL / min, 10% vol O2, 500 ppm NO, with N2 as the equilibrium gas, and the test was conducted at a reaction temperature of 100–360 °C.
[0036] The NO oxidation performance test results of the gradient honeycomb pore structure SiC catalytic membrane prepared in Example 3 are as follows: Figure 5 As shown, the NO oxidation efficiency can reach 79%.
Claims
1. A method for preparing a SiC catalytic membrane with a gradient honeycomb pore structure, characterized in that, Includes the following steps: A. SiC powder, catalytically active components, photosensitive resin monomers, photoinitiators and rheology modifiers are mixed in a predetermined ratio, and dispersed by ball milling and vacuum rotary degassing to obtain a uniform ceramic slurry suitable for photocuring. B. The ceramic slurry is introduced into a photopolymerization 3D printing device, and a ceramic film green body is formed by a layer-by-layer exposure curing process according to the preset gradient structure three-dimensional model. The gradient structure is manifested as the pore size and pore wall thickness of the honeycomb channels changing regularly along the spatial dimension. C. The green body is subjected to thermal decomposition and high-temperature sintering in sequence to obtain a SiC ceramic film with a gradient honeycomb pore structure; D. The SiC ceramic film is subjected to chemical etching to selectively modify some substances, expose and optimize catalytic active sites, and after drying, the gradient honeycomb pore structure SiC catalytic film is obtained.
2. The method for preparing a gradient honeycomb pore structure SiC catalytic film according to claim 1, characterized in that, In step A, the SiC powder has a particle size of 5-25 μm and a content of 40-55 wt% of the ceramic slurry; the catalytically active component is cobalt trioxide with a particle size of 0.5-20 μm and a content of 1-10 wt% of the ceramic slurry; the photosensitive resin is trimethylolpropane triacrylate, with a content of 37-57 wt% of the ceramic slurry; the auxiliary additives are BYK-P104S dispersant and BYK-045 defoamer, each with a content of 0.5-2 wt% of the ceramic slurry; and the photoinitiators are 814 photoinitiator and 789 photoinitiator, each with a content of 0.5-2 wt% of the ceramic slurry.
3. The method for preparing a gradient honeycomb pore structure SiC catalytic film according to claim 1, characterized in that, In step A, the ball milling speed is 400~600 rpm and the mixing time is 3~7 h; the degassing speed of the ceramic slurry is 1500~2500 rpm and the degassing time is 1~2 h.
4. The method for preparing a gradient honeycomb pore structure SiC catalytic film according to claim 1, characterized in that, In step B, the gradient honeycomb structure support unit constructed by the photopolymerization 3D printing process using 3D modeling software has a size of 1.0~2.0 mm, an inlet unit wall thickness of 0.1~0.5 mm, an outlet unit wall thickness of 0.4~0.8 mm, and a separation layer thickness of 50~200 μm.
5. The method for preparing a gradient honeycomb pore structure SiC catalytic membrane according to claim 1, characterized in that, In step B, the slice thickness for the photopolymerization 3D printing process is 25–75 μm, and the exposure intensity is 200–500 mJ / cm². 2 .
6. The method for preparing a gradient honeycomb pore structure SiC catalytic film according to claim 1, characterized in that, In step C, the temperature for the debinding process is 700~900 ℃, the heating rate is 1~2.5 ℃ / min, and the holding time is 3~5 h; the temperature for the sintering process is 1200~1500 ℃, the heating rate is 1~2.5 ℃ / min, and the holding time is 3~5 h.
7. The method for preparing a gradient honeycomb pore structure SiC catalytic membrane according to claim 1, characterized in that, In step D, the chemical etching solution is a nitric acid solution with an acid concentration of 1-4 mol / L, the immersion time is 2-5 h, the drying temperature is 100-120 ℃, and the drying time is 8-12 h.