Hexaaluminate / glass fiber honeycomb composite material for decomposing laughing gas as well as preparation method and application of hexaaluminate / glass fiber honeycomb composite material
By preparing hexaaluminate/glass fiber honeycomb composite materials, the problems of low specific surface area of catalyst support and uneven distribution of active sites were solved, achieving efficient decomposition of N2O, which is suitable for the treatment of nitrous oxide under industrial high air velocity conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-03-13
AI Technical Summary
Existing catalyst supports have low specific surface area and uneven distribution of active sites. Traditional hexaaluminate powders are prone to sintering and difficult to fix. Noble metal catalysts are expensive. Transition metal oxides have insufficient activity at low temperatures and are prone to deactivation at high temperatures, resulting in low N2O decomposition efficiency and uneconomical operation.
A method for preparing hexaaluminate/glass fiber honeycomb composite material was adopted. The glass fiber honeycomb carrier was pretreated by calcination, acid washing and baking. Hexaaluminate powder was dispersed in a xanthan gum-glycerol-water-polyethylene glycol system and mixed with silica sol to form a uniform silica sol composite suspension. This suspension was then coated on the glass fiber honeycomb carrier to form a stable composite material.
The specific surface area of the glass fiber honeycomb carrier is increased, ensuring the uniform distribution and firm adhesion of hexaaluminate active sites, achieving an N2O decomposition efficiency of over 95% at around 850℃, and making it suitable for industrial applications under high air velocity conditions.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental catalytic materials technology, specifically relating to a hexaaluminate / glass fiber honeycomb composite material for decomposing nitrous oxide, its preparation method, and its application. Background Technology
[0002] In the process of producing nitric acid via ammonia contact oxidation, the incomplete oxidation of ammonia easily produces the byproduct N2O, whose greenhouse effect is 298 times that of CO2. Therefore, highly efficient catalytic materials are urgently needed to achieve N2O decomposition. Traditional powder catalysts (such as hexaaluminates) are prone to sintering and difficult to immobilize. Powder catalysts placed in the reactor have low specific surface area and insufficient exposure of active sites. Limitations of existing N2O decomposition catalysts: Noble metal catalysts have advantages; Rh, Pt, and other noble metals exhibit high activity at low temperatures (200–400℃) (N2O conversion rate >90%), but are expensive and prone to sintering at high temperatures. Transition metal oxides suffer from insufficient activity at low temperatures and are prone to phase transition deactivation at high temperatures (>700℃). Hexaaluminate catalysts exhibit excellent high-temperature stability; however, traditional hexaaluminates are in powder form, resulting in large pressure drops and easy dispersion when used directly, requiring immobilization on a support.
[0003] Existing catalyst support technologies mainly include cordierite honeycomb ceramics, alumina-coated supports, and metal fiber supports, but these suffer from low specific surface area and low loading of active sites. Traditional processes typically involve impregnating a catalyst precursor solution onto the support, followed by calcination to form the active component. However, the problem with hexaaluminate powder catalysts is their synthesis temperature (>1200℃), which prevents direct loading via solution precursors, leading to uneven distribution of active sites. Coating methods involve mixing catalyst powder with a binder (such as silica sol) and then coating it onto the support surface. While this method allows for higher loading, the high-density powder is prone to sedimentation, resulting in uneven coating and potential clogging of support pores. Summary of the Invention
[0004] To address the problems in the prior art, this invention provides a hexaaluminate / glass fiber honeycomb composite material for decomposing nitrous oxide, its preparation method, and its application.
[0005] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The first aspect of this invention provides a method for preparing a hexaaluminate / glass fiber honeycomb composite material for decomposing nitrous oxide, comprising the following steps: (1) Cut the glass fiber honeycomb into blocks and calcine them at 500-600℃ for 2-3 hours. After calcination, acid washing and drying are performed to obtain the glass fiber honeycomb carrier. (2) The hexaaluminate powder was calcined at 600-800℃ for 2-4 h, and then ground. The ground hexaaluminate powder was added to xanthan gum-glycerol-water-polyethylene glycol system and dispersed evenly to obtain a hexaaluminate suspension. The hexaaluminate suspension was mixed with silica sol, stirred and mixed evenly, and then subjected to ultrasonic treatment. After ultrasonic treatment, a silica sol composite suspension was obtained. (3) The silica sol composite suspension prepared in step (2) is coated onto the glass fiber honeycomb carrier prepared in step (1). After coating, it is dried and then calcined at 500-600℃ for 2-3 hours. After calcination, it is cooled to room temperature to obtain the hexaaluminate / glass fiber honeycomb composite material.
[0006] Preferably, the mass-volume concentration of hexaaluminate powder in the hexaaluminate suspension in step (2) is 40–160 g / L.
[0007] Preferably, the preparation process of the xanthan gum-glycerol-water-polyethylene glycol system in step (2) is as follows: glycerol and water are mixed evenly to obtain a dispersion medium; polyethylene glycol is added to the dispersion medium and stirred to dissolve to obtain a glycerol-water-polyethylene glycol mixture; xanthan gum solution is added to the glycerol-water-polyethylene glycol mixture and stirred to mix evenly to obtain the xanthan gum-glycerol-water-polyethylene glycol system. The xanthan gum solution contains xanthan gum powder at a mass-volume concentration of 1%–2%; glycerol accounts for 15%–25% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system; water accounts for 25%–35% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system; polyethylene glycol accounts for 5%–15% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system; and the xanthan gum solution accounts for 35%–45% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system.
[0008] Preferably, in step (2), the volume ratio of the hexaaluminate suspension to the silica sol is (2-5):1, and the SiO2 content in the silica sol is 20wt%-30wt%.
[0009] More preferably, the particle size of SiO2 in the silica sol is 10–20 nm.
[0010] Preferably, the D50 particle size of the hexaaluminate powder after grinding in step (2) is 1 to 5 μm, and the D90 particle size is not greater than 10 μm.
[0011] More preferably, the grinding method in step (2) is ball milling, using zirconia balls as the grinding medium, and the grinding time is 1 to 2 hours.
[0012] Preferably, in step (2), the hexaaluminate powder is synthesized by the method in the reference (Liu et al., Preparation of nanospheres of LaAlO3 and its defluorination performance under acidic conditions (Chemical Industry Progress, 2024, 43 (6), 43-47)). LaAlO3 hexaaluminate is prepared by direct coprecipitation. By controlling the reaction condition of pH=6, the uniform combination of La³⁺ and Al³⁺ is achieved, and hexaaluminate is obtained.
[0013] Preferably, the heating rate of step (1) calcination, step (2) calcination, and step (3) roasting is 4-5℃ / min.
[0014] Preferably, in step (2), the stirring speed is 500-800 rpm and the stirring time is 20-40 min; in step (2), the ultrasonic power is 150-300W, the ultrasonic frequency is 40-50 kHz, the ultrasonic time is 10-30 min, and the ultrasonic process uses a pulse mode (working for 2 seconds and pausing for 1 second) to prevent local overheating.
[0015] More preferably, the viscosity of the silica sol composite suspension after ultrasonic treatment is 300-600 mPa·s (25℃), and the pH value is 7.0-9.0.
[0016] Preferably, step (1) involves ultrasonic soaking in nitric acid with a concentration of 1 to 1.5 mol / L for 1 to 1.5 hours for acid washing.
[0017] Preferably, in step (1), the glass fiber honeycomb is cut into cubes with a side length of 2cm to 3cm.
[0018] Preferably, in step (3), a pressure spray gun or ultrasonic spraying equipment is used for spraying, and the nozzle diameter of the spraying equipment is 0.2 to 0.8 mm.
[0019] Preferably, in step (3), the rotation speed of the glass fiber honeycomb carrier is 10 to 50 rpm; the distance between the spraying equipment and the surface of the glass fiber honeycomb carrier is 15 to 30 cm; and the spraying pressure is 0.2 to 0.5 MPa.
[0020] Preferably, step (3) is carried out by intermittent spraying, spraying for 5 to 30 seconds and pausing for 1 to 5 minutes, so that the slurry on the surface of the carrier can fully penetrate and flow level under the action of capillary, while avoiding excessive slurry from clogging the honeycomb channels.
[0021] A second aspect of the present invention provides a hexaaluminate / glass fiber honeycomb composite material prepared by the above preparation method.
[0022] The third aspect of the present invention provides an application of the hexaaluminate / glass fiber honeycomb composite material described in the second aspect in the decomposition of nitrous oxide (N2O).
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention pre-treats glass fiber honeycomb to prepare glass fiber honeycomb carriers. First, low-speed heating and calcination are used to avoid cracking caused by thermal stress, while simultaneously ablating residual organic matter and impurities. Further acid washing removes surface organic contaminants and metallic impurities, forming a micron-level rough surface. After the aforementioned calcination pre-treatment and acid washing etching process, the specific surface area of the glass fiber honeycomb is increased from 2 to 10 m² of the original fiber. 2 / g increased to 30-40 m 2 / g.
[0024] (2) In this invention, the hexaaluminate is calcined to remove moisture and impurities, stabilize the crystal structure, and ensure that its catalytic active sites are in the best state. After calcination, its particle size distribution is controlled by ball milling to prevent blockage of the honeycomb channels of the glass fiber honeycomb carrier during the spraying process, so that the hexaaluminate can penetrate deeply and adhere firmly to the microstructure of the glass fiber.
[0025] (3) The present invention prepares xanthan gum-glycerol-water-polyethylene glycol system to disperse hexaaluminate. By utilizing the stability of xanthan gum and the dispersibility of glycerol-water-polyethylene glycol, hexaaluminate is formulated into a uniform and stable hexaaluminate suspension, and mixed with silica sol to prepare a silica sol composite suspension. The composite suspension has good stability and dispersibility and is suitable for subsequent carrier spraying.
[0026] (4) The hexaaluminate / glass fiber honeycomb composite material of the present invention has a good ability to catalyze the decomposition of N2O, and can achieve a decomposition efficiency of about 95% at about 850°C. Attached Figure Description
[0027] Figure 1 The efficiency curves of N2O decomposition by hexaaluminate / glass fiber honeycomb composite material and hexaaluminate powder in Examples 1 to 4 of this invention are shown. Figure 2 The efficiency curves of N2O decomposition by the hexaaluminate / glass fiber honeycomb composite material in Example 2 of the present invention at different space velocities are shown. Figure 3 The curves show the change in the powder catalyst loading rate on the surface of the hexaaluminate / glass fiber honeycomb composite material under ultrasonic treatment in Examples 1, 5 to 7 of this invention. Detailed Implementation
[0028] The method described in this invention will be explained in detail below with specific examples.
[0029] Example 1 The specific steps of the preparation method for a hexaaluminate / glass fiber honeycomb composite material for decomposing nitrous oxide are as follows: (1) The glass fiber honeycomb was cut into cubes with a side length of 2 cm. The cut glass fiber honeycomb was subjected to high-temperature treatment, with the temperature increased to 500°C at a rate of 5°C / min and calcined for 2 h. The calcined glass fiber was then subjected to acid washing treatment by ultrasonic soaking in 1 mol / L nitric acid at room temperature for 1 h to obtain pretreated glass fiber honeycomb. The pretreated glass fiber honeycomb was then dried in an oven at 100°C for 1 h to obtain the glass fiber honeycomb carrier. After the calcination pretreatment and acid washing etching process, the specific surface area of the glass fiber honeycomb was increased from 2 to 10 m² of the original fiber. 2 / g increased to 30-40 m 2 / g; (2) Take 10 mL of glycerol and 15 mL of water respectively and mix them as a dispersion medium. Add 5 mL of polyethylene glycol as a dispersant to the dispersion medium and stir with a magnetic stirrer until completely mixed to form a glycerol-water-polyethylene glycol mixture. Take 0.2 g of xanthan gum powder and dissolve it in 20 mL of deionized water. Stir at 60°C until completely dissolved to obtain a xanthan gum solution. Slowly add the xanthan gum solution to the glycerol-water-polyethylene glycol mixture and continue stirring for 10 to 20 min to ensure uniform mixing to form a xanthan gum-glycerol-water-polyethylene glycol system. (3) Reference method (Liu et al. (Chemical Industry Progress. 2024, 43 (6), 43-47)), LaAlO3 hexaaluminate was prepared by direct coprecipitation, and the reaction condition of pH=6 was controlled to achieve La 3+ With Al 3+ The uniform combination of the components yielded hexaaluminate; the synthesized hexaaluminate powder was calcined at 500℃ for 2 h, and the calcined hexaaluminate powder was ball-milled for 1 h using zirconia balls as the grinding medium. After ball milling, the D50 particle size was 2 μm and the D90 particle size was 10 μm; then 2 g of ball-milled hexaaluminate powder was added to the xanthan gum-glycerol-water-polyethylene glycol system prepared in step (2), and initially dispersed by magnetic stirring for 30 min, and then further broken up the particle agglomerates by ultrasonic treatment for 30 min to obtain a uniform and stable hexaaluminate suspension; (4) Add 12.5 mL of neutral silica sol to the hexaaluminate suspension prepared in step (3) according to a volume ratio of 4:1 between the hexaaluminate suspension and silica sol. The neutral silica sol has a SiO2 content of 25 wt% and a particle size of 25 nm. Place the mixture on a magnetic stirrer and stir at 600 rpm for 30 min to ensure thorough mixing. Then transfer the mixture to an ultrasonic processor and sonicate it at a power of 200 W and a frequency of 40 kHz for 30 min. During the sonication process, a pulse mode (working for 2 seconds and pausing for 1 second) is used to prevent local overheating. After ultrasonic treatment, a silica sol composite suspension with a viscosity of 300 mPa·s (25 °C) and a pH of 9.0 is obtained. (5) Add the silica sol composite suspension prepared in step (4) into a pressure spray gun with a nozzle diameter of 0.4 mm and spray it onto the glass fiber honeycomb carrier prepared in step (1). During spraying, the rotation speed of the glass fiber honeycomb carrier is 30 rpm, the distance between the spray gun and the glass fiber honeycomb carrier is 20 cm, and the spraying pressure is 0.5 MPa. Adopt an intermittent spraying strategy. After spraying for 30 seconds, pause for 5 minutes to allow the slurry on the surface of the glass fiber honeycomb carrier to fully penetrate and level under the action of capillary action, while avoiding excessive slurry from clogging the honeycomb channels. Repeat the above spraying-standing process 3 times until the slurry on the surface of the glass fiber honeycomb is evenly covered. (6) The wet composite material obtained in step (5) is first placed in an oven and dried at 100°C for 3 hours to allow the moisture in the slurry to evaporate initially and the structure to stabilize initially. The fully dried composite material is placed in a muffle furnace and calcined in an air atmosphere by programmed heating from room temperature to 500°C at a heating rate of 5 °C / min, and held at this temperature for 2 hours. After calcination, the composite material is cooled to room temperature with the furnace to obtain the hexaaluminate / glass fiber honeycomb composite material.
[0030] Example 1 prepared a hexaaluminate / glass fiber honeycomb composite material with a hexaaluminate loading rate of 20% and a loading amount of 0.100 g / cm³. 3 .
[0031] Example 2 Example 2 is basically the same as Example 1, except that in step (3), 4 g of ball-milled hexaaluminate powder is added to the xanthan gum-glycerol-water-polyethylene glycol system prepared in step (2). The hexaaluminate / glass fiber honeycomb composite material prepared in Example 2 has a hexaaluminate loading rate of 25% and a loading amount of 0.190 g / cm³. 3 .
[0032] Example 3 Example 3 is basically the same as Example 1, except that in step (3), 6 g of ball-milled hexaaluminate powder is added to the xanthan gum-glycerol-water-polyethylene glycol system prepared in step (2). The hexaaluminate / glass fiber honeycomb composite material prepared in Example 3 has a hexaaluminate loading rate of 27% and a loading amount of 0.250 g / cm³. 3 .
[0033] Example 4 Example 4 is basically the same as Example 1, except that in step (3), 8 g of ball-milled hexaaluminate powder is added to the xanthan gum-glycerol-water-polyethylene glycol system prepared in step (2). In Example 4, the hexaaluminate loading rate is 32%, and the loading amount is 0.30 g / cm³. 3 .
[0034] Performance testing: The N2O decomposition experiment was conducted using the hexaaluminate / glass fiber honeycomb composite material prepared according to this invention. The specific process was as follows: The hexaaluminate / glass fiber honeycomb composite material prepared according to this invention was placed in a high-throughput evaluation device, and a reaction gas containing the pollutant nitrous oxide (N2O) was introduced at a certain rate. The composition of the reaction gas was N2O (7%) and He (93%). The high-throughput evaluation device was heated to 500℃, and the concentration of the degraded gas was analyzed using infrared photochromatography. The removal rate of nitrous oxide was obtained through a standard curve. The temperature was further increased, and the removal rate of nitrous oxide by the hexaaluminate / glass fiber honeycomb composite material was measured every 50℃ within the range of 550–900℃.
[0035] (1) N2O removal rate under different hexaaluminate loadings in Examples 1 to 4 The hexaaluminate / glass fiber honeycomb composite materials prepared in Examples 1 to 4 were placed in a high-throughput evaluation device. These composite materials, shaped as glass fiber blocks with sides of 2 cm, were used for N₂O decomposition experiments. The reaction gas inlet rate was 100 mL / min, at which point the space velocity reached 10000 h⁻¹. -1 The N2O removal rate results are as follows: Figure 1 As shown.
[0036] Depend on Figure 1It is known that the removal efficiency of N2O exhibits a diminishing marginal effect with increasing hexaaluminate loading. Specifically, when the hexaaluminate content in the hexaaluminate suspension increases from 2g to 4g, the removal efficiency significantly improves. However, when the hexaaluminate content in the hexaaluminate suspension further increases to 6g or even 8g, the efficiency gain is far lower than the increase in catalyst dosage. This indicates that at a hexaaluminate loading of 4g, the active sites of the catalyst are close to saturation, achieving excellent catalytic performance. Therefore, this invention selects 4g as the optimized hexaaluminate loading, which does not pursue an absolute efficiency extreme, but rather achieves the best balance between catalytic performance, material economy, and coating stability. This ensures high removal efficiency, significantly reduces raw material costs, and effectively avoids the risk of pore blockage and coating peeling caused by excessive loading.
[0037] (2) Removal rate of N2O at different gas space velocities The results above indicate that the 4g hexaaluminate loading (Example 2) is the optimal hexaaluminate loading. Therefore, the N2O removal rate of the composite material in Example 2 was measured at different gas hourly space velocities. The gas was introduced into the high-throughput evaluation device at rates of 100 mL / min, 200 mL / min, and 300 mL / min, respectively, i.e., space velocities of 10000 h⁻¹. -1 20000h -1 30000h -1 The N2O removal rate results are as follows: Figure 2 As shown.
[0038] Depend on Figure 2 It can be seen that even if the airspeed is 10,000 h... -1 Increase to 30,000h -1 Although the N2O removal efficiency of the composite material of this invention is expected to decrease somewhat, it still remains at a high level (>85%). This confirms that the present invention still possesses excellent and practical catalytic performance under high space velocities typical of industrial plants. High space velocities mean that a unit of catalyst can handle a larger volume of gas, which is key to achieving reactor miniaturization and reducing equipment investment. Therefore, this composite material successfully overcomes the bottleneck of laboratory catalysts, which struggle to balance high activity and high processing capacity.
[0039] Experimental Example 5 Example 5 is basically the same as Example 1, except that in step (4), the xanthan gum-glycerol-water-polyethylene glycol system was prepared according to a volume ratio of hexaaluminate suspension to silica sol of 5:1, and the amount of silica sol added was 10 mL; the amount of hexaaluminate powder added was 1.92 g. The hexaaluminate loading rate in Example 5 was 19.7%, and the loading amount was 0.092 g / cm³. 3 .
[0040] Experimental Example 6 Example 6 is basically the same as Example 1, except that in step (4), the xanthan gum-glycerol-water-polyethylene glycol system was prepared according to a volume ratio of hexaaluminate suspension to silica sol of 3:1, and the amount of silica sol added was 16.7 mL; the amount of hexaaluminate powder added was 2.13 g. The hexaaluminate loading rate in Example 6 was 20.6%, and the loading amount was 0.114 g / cm³. 3 .
[0041] Experimental Example 7 Example 7 is basically the same as Example 1, except that in step (4), the xanthan gum-glycerol-water-polyethylene glycol system was prepared according to a volume ratio of hexaaluminate suspension to silica sol of 2:1, and the amount of silica sol added was 25 mL; the amount of hexaaluminate powder added was 2.4 g. The hexaaluminate loading rate in Example 7 was 21.3%, and the loading amount was 0.119 g / cm³. 3 .
[0042] Performance testing: In composite materials, silica sol mainly plays a binding role. To evaluate the effect of silica sol dosage on catalyst loading stability, the samples were subjected to ultrasonic treatment of varying durations to simulate the usage environment, and the changes in loading were measured. The ultrasonic conditions were: ultrasonic power of 250W and ultrasonic frequency of 40kHz. Ultrasonic treatment for 30 minutes was recorded as one cycle. The loading rate of composite materials with different silica sol dosages in Examples 1, 5-7 was measured as a function of ultrasonic frequency. The results are as follows: Figure 3 As shown.
[0043] Figure 3 The results show that after a period of time, the catalyst loading rate tends to stabilize. At a volume ratio of 4:1 (Example 1), the catalyst loading rate decreases most slowly after ultrasonication, and its residual loading rate is significantly higher than in other examples. This phenomenon demonstrates that this ratio ensures the formation of a stable three-dimensional bonding network in the silica sol while avoiding coating embrittlement caused by excessive binder introduction. Thus, it achieves excellent adhesion strength and durability of the catalyst layer while significantly saving binder usage. The preferred ratio of this invention maintains a stable high loading platform even under long-term ultrasonic treatment, reflecting the reliability and long-term effectiveness of this composite material in practical applications.
[0044] The above experiments demonstrate that, even when hexaaluminate is loaded onto glass fiber honeycomb, it still exhibits a certain catalytic effect. Controlling the gas space velocity can yield better results. In industry, the problem with powdered catalysts is their difficulty in placement during use. While unloaded powdered catalysts showed good catalytic performance in experiments because they are more readily contacted with the gas in the evaluation pipeline, achieving such removal rates is difficult in industrial applications. This invention reduces the use of powdered catalysts, but in practical applications, the removal rate of pollutants in the gas is still only around 80%. Solving the problem of catalyst placement difficulties in the removal of harmful waste gases in industrial production has broad engineering application prospects.
[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a hexaaluminate / glass fiber honeycomb composite material for decomposing nitrous oxide, characterized in that, Includes the following steps: (1) Cut the glass fiber honeycomb into blocks and calcine them at 500-600℃ for 2-3 hours. After calcination, acid washing and drying are carried out in sequence to obtain glass fiber honeycomb carrier. (2) The hexaaluminate powder was calcined at 600-800℃ for 2-4 h, and then ground. The ground hexaaluminate powder was added to xanthan gum-glycerol-water-polyethylene glycol system and dispersed evenly to obtain a hexaaluminate suspension. The hexaaluminate suspension was mixed with silica sol, stirred and mixed evenly, and then subjected to ultrasonic treatment. After ultrasonic treatment, a silica sol composite suspension was obtained. (3) The silica sol composite suspension prepared in step (2) is coated onto the surface of the glass fiber honeycomb carrier prepared in step (1). After coating, it is dried and then calcined at 500-600℃ for 2-3 hours. After calcination, it is cooled to room temperature to obtain the hexaaluminate / glass fiber honeycomb composite material.
2. The preparation method according to claim 1, characterized in that, In step (2), the mass-volume concentration of hexaaluminate powder in the hexaaluminate suspension is 40–160 g / L.
3. The preparation method according to claim 2, characterized in that, Step (2) The preparation process of the xanthan gum-glycerol-water-polyethylene glycol system is as follows: Glycerol and water are mixed evenly to obtain a dispersion medium. Polyethylene glycol is added to the dispersion medium and stirred to dissolve to obtain a glycerol-water-polyethylene glycol mixture. The xanthan gum solution is added to the glycerol-water-polyethylene glycol mixture and stirred to mix evenly to obtain the xanthan gum-glycerol-water-polyethylene glycol system. The xanthan gum solution contains xanthan gum powder at a mass-volume concentration of 1%–2%; glycerol accounts for 15%–25% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system; water accounts for 25%–35% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system; polyethylene glycol accounts for 5%–15% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system; and the xanthan gum solution accounts for 35%–45% of the volume percentage of the xanthan gum-glycerol-water-polyethylene glycol system.
4. The preparation method according to claim 3, characterized in that, In step (2), the volume ratio of the hexaaluminate suspension to the silica sol is (2-5):1, and the SiO2 content in the silica sol is 20wt%-30wt%.
5. The preparation method according to claim 1, characterized in that, After grinding in step (2), the D50 particle size of the hexaaluminate powder is 1-5 μm, and the D90 particle size is no greater than 10 μm.
6. The preparation method according to claim 1, characterized in that, The heating rates for steps (1) calcination, (2) calcination, and (3) roasting are all 4℃ / min to 5℃ / min.
7. The preparation method according to claim 1, characterized in that, Step (2) The stirring speed is 500-800 rpm and the stirring time is 20-40 min; Step (2) The ultrasonic power is 150-300 W, the ultrasonic frequency is 40-50 kHz, and the ultrasonic time is 10-30 min; Step (1) Acid washing treatment is performed by ultrasonic soaking in nitric acid with a concentration of 1-2 mol / L for 1-1.5 h.
8. The preparation method according to claim 5, characterized in that, Step (3) The coating method is spraying. When spraying, a pressure spray gun or ultrasonic spraying equipment is used. The nozzle diameter of the spraying equipment is 0.2 to 0.8 mm. The rotation speed of the glass fiber honeycomb carrier is 10 to 50 rpm. The distance between the spraying equipment and the surface of the glass fiber honeycomb carrier is 15 to 30 cm. The spraying pressure is 0.2 to 0.5 MPa.
9. A hexaaluminate / glass fiber honeycomb composite material prepared by the method according to any one of claims 1 to 8.
10. The application of the hexaaluminate / glass fiber honeycomb composite material of claim 9 in the decomposition of nitrous oxide.