A flower-like CeO2 supported transition metal oxide catalytic coating-net-like porous material and a preparation method and application thereof

Abstract

The application provides a flower-shaped CeO2 loaded transition metal oxide catalytic coating-meshed porous material and a preparation method and application thereof, and belongs to the technical field of porous medium combustion. The application utilizes a coprecipitation method to precipitate a precipitator and cerium salt to prepare flower-shaped CeO2, then adds transition metal salt to prepare flower-shaped CeO2 loaded transition metal oxide, sprays the flower-shaped CeO2 loaded transition metal oxide to the surface of a meshed porous material, and obtains the flower-shaped CeO2 loaded transition metal oxide catalytic coating-meshed porous material after heat treatment. The prepared flower-shaped CeO2 loaded transition metal oxide catalytic coating-meshed porous material has high infrared radiation performance, low NO x emission characteristics, and can be used for porous medium ammonia combustion.

Description

Technical Field

[0001] This invention relates to the field of porous media combustion technology, and in particular to a flower-like CeO2-supported transition metal oxide catalytic coating-network porous material, its preparation method, and its application. Background Technology

[0002] Ammonia, as a novel zero-carbon fuel and a good hydrogen storage medium, produces no carbon oxide emissions during combustion, making it a promising clean fuel. However, ammonia combustion still faces several challenges. Compared to hydrocarbon fuels, it exhibits lower combustion stability, lower combustion temperature, and higher NOx emissions. x High emissions and low flame propagation speed. NOx from ammonia combustion. x It originates from two aspects: one is thermal NO. x This means that the combustion temperature is too high, causing N2 and O2 in the air to react chemically to produce NO. x Second, fuel-type NO x This means that ammonia fuel contains nitrogen (N), which is oxidized to NO during combustion. x Among them, fuel-type NO x It is the main source, and fuel-type NO x The formation rate of NO is higher than that of thermal NO. x Much faster.

[0003] Porous media combustion is a stable, "super-insulated" combustion of fuel gas and combustion air within a porous medium material with high temperature resistance and good heat transfer properties. The heat generated during combustion is transferred upstream of the burner through thermal convection and conduction, thereby increasing the initial combustion temperature of the premixed fuel gas, enabling direct combustion of low-calorific-value gases, and widening the lean-burn limit of the fuel while reducing NO₂ levels. x Pollutant emissions. Currently, stable combustion of pure ammonia can be achieved in porous media, reducing NO emissions. x Emissions. However, ammonia combustion in porous media still faces challenges. Firstly, although porous media combustion technology can reduce NO emissions... x Emissions, but can only address thermal NOx emissions. x The issue of emissions is that ammonia combustion primarily produces fuel-type NO. x The levels still exceed the standard. Secondly, although porous media combustion technology can achieve stable combustion of ammonia, the laminar combustion rate of ammonia is low, and the combustion products are mainly H2O(g) and N2(g), resulting in poor high-temperature radiation performance. Consequently, the heat radiated by ammonia during combustion in porous media is lower than that of hydrocarbon fuels, and the combustion efficiency is not high, which restricts its practical application in industry.

[0004] At present, the skilled person has carried out in-depth research and technical development to solve the problem of ammonia combustion in porous media, such as Chinese patent CN 116498980A discloses a porous media combustion device for ammonia catalytic pyrolysis combustion, which uses the combustion flue gas for preheating of ammonia in the catalytic pyrolysis reactor, and makes ammonia partially pyrolyze into N2 and H2 under the action of the catalyst, and the mixed gas after pyrolysis is introduced into the porous media burner to burn. This technology is carried out by designing the burner, and the high-temperature flue gas generated by combustion is used to deliver energy to the outside and preheat ammonia for ammonia catalytic pyrolysis. It is beneficial to improve the combustion efficiency, reduce the fuel type NO x emission, but part of the heat of ammonia combustion is needed for ammonia catalytic pyrolysis, which loses the energy delivered to the outside, thereby affecting the high-temperature radiation performance, and the increased catalytic pyrolysis device also increases the complexity of the combustion system and the difficulty of practical application. SUMMARY

[0005] The purpose of the present application is to provide a flower-shaped CeO2 supported transition metal oxide catalytic coating-net-like porous material and a preparation method and application thereof, and the flower-shaped CeO2 supported transition metal oxide catalytic coating-net-like porous material for ammonia combustion has low NO x emission and excellent high-temperature infrared radiation efficiency, and the preparation process is simple and low in cost.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a flower-shaped CeO2 supported transition metal oxide catalytic coating-net-like porous material, comprising the following steps:

[0008] Mixing cerium salt, a first precipitating agent and water to carry out a first coprecipitation reaction to obtain a flower-shaped cerium dioxide precursor;

[0009] Carrying out a first calcination on the flower-shaped cerium dioxide precursor to obtain a flower-shaped cerium dioxide;

[0010] Mixing the flower-shaped cerium dioxide, a transition metal nitrate, a second precipitating agent and water to carry out a second coprecipitation reaction to obtain a cerium dioxide supported transition metal oxide precursor;

[0011] Carrying out a second calcination on the cerium dioxide supported transition metal oxide precursor to obtain a cerium dioxide supported transition metal oxide;

[0012] Mixing the cerium dioxide supported transition metal oxide and a binder, spraying the obtained coating slurry on the surface of the net-like porous material, and sequentially carrying out drying and heat treatment to obtain a flower-shaped CeO2 supported transition metal oxide catalytic coating-net-like porous material.

[0013] Preferably, the cerium salt comprises cerium nitrate; the first precipitant comprises ammonium bicarbonate, ammonium carbonate, sodium carbonate or sodium bicarbonate; and the molar ratio of the first precipitant to the cerium salt is 1-5:1.

[0014] Preferably, the step of mixing the cerium salt, the first precipitant and water comprises mixing the cerium salt with water to obtain a cerium salt solution, mixing the first precipitant with water to obtain a first precipitant solution, and adding the first precipitant solution to the cerium salt solution; the concentration of the cerium salt solution is 0.01-0.5 mol / L, and the concentration of the first precipitant solution is 0.01-0.5 mol / L.

[0015] The temperature of the first co-precipitation reaction is 0-80°C, and the time is 0.1-8 h.

[0016] Preferably, the temperature of the first calcination is 500-600°C, and the holding time is 1-4 h, and the temperature is raised to the temperature of the first calcination at a rate of 0.5-5°C / min.

[0017] Preferably, the transition metal nitrate comprises one or more of copper nitrate, manganese nitrate, cobalt nitrate, iron nitrate and nickel nitrate; and the second precipitant comprises ammonium bicarbonate, ammonium carbonate, sodium carbonate or sodium bicarbonate.

[0018] Preferably, the ratio of the flower-like cerium dioxide, the transition metal nitrate and the second precipitant is (10-100) g:(0.01-0.1) mol:(0.01-0.1) mol; and the molar ratio of the second precipitant to the transition metal nitrate is (1-5):1.

[0019] The step of mixing the flower-like cerium dioxide, the transition metal nitrate, the second precipitant and water comprises dispersing the flower-like cerium dioxide in water to obtain a flower-like cerium dioxide suspension, mixing the transition metal nitrate with water to obtain a transition metal nitrate solution, mixing the second precipitant with water to obtain a second precipitant solution, and adding the transition metal nitrate solution to the flower-like cerium dioxide suspension and then adding the second precipitant solution dropwise; the content of the flower-like CeO2 in the flower-like cerium dioxide suspension is 5-50 wt%; the concentration of the transition metal nitrate solution is 0.01-0.5 mol / L, and the concentration of the second precipitant solution is 0.01-0.5 mol / L.

[0020] Preferably, the temperature of the second co-precipitation reaction is 0-60°C, and the time is 0.5-6 h; the temperature of the second calcination is 500-600°C, and the holding time is 1-4 h, and the temperature is raised to the temperature of the second calcination at a rate of 0.5-5°C / min.

[0021] Preferably, the material of the reticular porous material comprises silicon carbide, aluminum oxide or zirconium oxide.

[0022] The temperature of the heat treatment is 500-650 DEG C, and the holding time is 1-4 h; the temperature is raised to the temperature of the heat treatment at a rate of 0.5-3 DEG C / min.

[0023] The application provides a flower-shaped CeO2 loaded transition metal oxide catalytic coating-reticular porous material prepared by the preparation method.

[0024] The application provides application of the flower-shaped CeO2 loaded transition metal oxide catalytic coating-reticular porous material in the field of porous medium ammonia combustion.

[0025] The application provides a preparation method of a flower-shaped CeO2 loaded transition metal oxide catalytic coating-reticular porous material. 2 / g), and high active oxygen content (O active / (O active +O lattice ) = 54.8%) of the coating formed after the heat treatment. x The prepared flower-shaped CeO2 loaded transition metal oxide catalytic coating-reticular porous material has the characteristics of high infrared radiation performance and low NO x emission, can be used for porous medium ammonia combustion, and can achieve the purposes of improving high-temperature radiation performance of ammonia combustion in the porous material and reducing fuel-type NOx emission exceeding the standard.

[0026] Compared with the prior art, the application has the following positive effects:

[0027] The application combines the porous medium combustion technology with the catalytic combustion technology, utilizes the structural characteristics of high surface area of the porous material, sprays the flower-shaped CeO2 loaded transition metal oxide catalytic coating on the surface, the oxygen vacancies on the surface of cerium oxide have good oxygen storage capacity and redox capacity, which is beneficial to the SCR reaction of unreacted NH3 and NO x in the combustion process, thereby reducing fuel-type NO x emission and reducing the leakage of unburned NH3.

[0028] Firstly, the multiple pore structures generated by the internal and mutual stacking of the flower-like CeO2 particles are used to adjust the surface morphology of the coating. The micro-porosity of the coating surface is improved, the projection depth and scattering area are increased, which is beneficial to enhance the absorption and emission of infrared waves in the coating, and thus the infrared emissivity is improved. The improvement of the infrared emissivity is beneficial to improve the infrared radiation performance of the porous material. Secondly, on the basis of the flower-like CeO2, transition metal oxides are loaded to stimulate the oxygen vacancies of CeO2, improve the relative content of surface active oxygen and the migration rate of lattice oxygen, and thus the catalytic activity of CeO2 is increased. In addition, compared with single metal oxide catalyst, there is a synergistic effect between multi-component metal oxide catalysts, which can significantly improve the catalytic activity, promote the NH3-SCR reaction, and reduce the NO x emission. Furthermore, the loaded transition metal oxides are in the form of sub-micron particles, which are well dispersed on the flower-like CeO2 and can inhibit the sintering phenomenon in the combustion process, thereby delaying the deactivation of the coating catalyst in the combustion process. The coating prepared by the present application has the characteristics of high specific surface area, which is also beneficial to the adsorption of ammonia in the combustion process and promotes the catalytic combustion reaction.

[0029] The porous medium burner prepared by the present application has a radiation efficiency of 80-92% at 800-1200℃, a heating efficiency of 39-43℃ / min, and the NOx emission of the porous medium burner is reduced from 8000-10000ppm to meet the NO x emission standard compared with the porous medium burner without catalytic coating.

[0030] The present application has the characteristics of simple process and low cost, the net-like porous material used is not limited to a specific material, and the application flexibility is high, which can greatly reduce the application difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 SEM image of the flower-like CeO2 powder prepared in Example 1 of the present application;

[0032] Figure 2 SEM image of the flower-like CeO2 powder loaded with copper oxide prepared in Example 1 of the present application;

[0033] Figure 3 SEM image of the flower-like CeO2 powder loaded with copper and manganese oxides prepared in Example 2 of the present application;

[0034] Figure 4 SEM image of the fracture section of the pore rib of the flower-like CeO2 loaded with transition metal oxide catalytic coating-net-like porous material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0035] In the present application, the required raw materials or reagents are commercially available unless otherwise specified.

[0036] The present application provides a preparation method of a flower-like CeO2 supported transition metal oxide catalytic coating-meshed porous material, comprising the following steps:

[0037] Mixing cerium salt, first precipitant and water to perform a first co-precipitation reaction to obtain a flower-like cerium dioxide precursor;

[0038] Performing a first calcination on the flower-like cerium dioxide precursor to obtain a flower-like cerium dioxide;

[0039] Mixing the flower-like cerium dioxide, transition metal nitrate, second precipitant and water to perform a second co-precipitation reaction to obtain a cerium dioxide supported transition metal oxide precursor;

[0040] Performing a second calcination on the cerium dioxide supported transition metal oxide precursor to obtain a cerium dioxide supported transition metal oxide;

[0041] Mixing the cerium dioxide supported transition metal oxide and a binder, spraying the obtained coating slurry on the surface of a meshed porous material, and sequentially performing drying and heat treatment to obtain a flower-like CeO2 supported transition metal oxide catalytic coating-meshed porous material.

[0042] The present application mixes cerium salt, first precipitant and water to perform a first co-precipitation reaction to obtain a flower-like cerium dioxide precursor.

[0043] In the present application, the cerium salt preferably includes cerium nitrate; the first precipitant includes ammonium bicarbonate, ammonium carbonate, sodium carbonate or sodium bicarbonate; and the molar ratio of the first precipitant to cerium salt is preferably 1-5:1, and more preferably 2-3:1.

[0044] In the present application, the step of mixing the cerium salt, first precipitant and water preferably comprises: mixing the cerium salt with water to obtain a cerium salt solution, mixing the first precipitant with water to obtain a first precipitant solution, and dropping the first precipitant solution into the cerium salt solution. The present application preferably dissolves the cerium salt in water, stirs to obtain a cerium salt solution at a temperature range of 0-80℃, dissolves the precipitant in water, stirs to obtain a first precipitant solution at a temperature range of 0-80℃, continuously stirs the above cerium salt solution at a temperature range of 0-80℃, drops the first precipitant solution into the cerium salt solution, continues to stir for 0.1-3h, and more preferably 2h after dropping, and then performs a first co-precipitation reaction under static conditions.

[0045] In the present application, the concentration of the cerium salt solution is preferably 0.01-0.5 mol / L, more preferably 0.1-0.3 mol / L; and the concentration of the first precipitant solution is preferably 0.01-0.5 mol / L, more preferably 0.1-0.3 mol / L.

[0046] The amount of water used for mixing the cerium salt, the first precipitant and water in the present application can meet the concentration of each solution as described above.

[0047] In the present application, the temperature of the first co-precipitation reaction is preferably 0-80°C, more preferably 0-50°C, and further preferably 25-30°C, and the time is preferably 0.1-8 h, more preferably 2-6 h; and the first co-precipitation reaction is preferably carried out under static condition.

[0048] After the first co-precipitation reaction is completed, the product obtained is preferably filtered, the precipitate is collected by centrifugation, the precipitate is washed with deionized water and ethanol alternately, and the precipitate is dried at 80-110°C for 12-36 h to obtain a flower-like CeO2 precursor powder.

[0049] After the flower-like cerium dioxide precursor is obtained, the flower-like cerium dioxide precursor is subjected to first calcination to obtain flower-like cerium dioxide.

[0050] In the present application, the temperature of the first calcination is preferably 500-600°C, more preferably 500-550°C; the holding time is preferably 1-4 h, more preferably 2-3 h; the temperature is raised to the temperature of the first calcination at a rate of 0.5-5°C / min (more preferably 1-3°C / min); and the first calcination is preferably carried out in an air atmosphere. After the calcination is completed, the furnace is cooled to room temperature to obtain a flower-like CeO2 powder.

[0051] After the flower-like cerium dioxide is obtained, the flower-like cerium dioxide, a transition metal nitrate, a second precipitant and water are mixed to carry out a second co-precipitation reaction to obtain a cerium dioxide supported transition metal oxide precursor.

[0052] In the present application, the transition metal nitrate preferably includes one or more of copper nitrate, manganese nitrate, cobalt nitrate, iron nitrate and nickel nitrate; and the second precipitant preferably includes ammonium bicarbonate, ammonium carbonate, sodium carbonate or sodium bicarbonate. When the transition metal nitrate is two or more of the above, the present application does not have a special limitation on the ratio of different kinds of transition metal nitrates, and any ratio is acceptable.

[0053] In the present application, the ratio of the amounts of the flower-like cerium dioxide, the transition metal nitrate and the second precipitant is preferably 10-100 g:0.01-0.1 mol:0.01-0.1 mol, and the molar ratio of the second precipitant to the transition metal nitrate is preferably (1-5):1.

[0054] In the present application, the step of mixing the flower-like ceria, the transition metal nitrate, the second precipitant and water preferably comprises: dispersing the flower-like ceria in water to obtain a flower-like ceria suspension; mixing the transition metal nitrate with water to obtain a transition metal nitrate solution, mixing the second precipitant with water to obtain a second precipitant solution; adding the transition metal nitrate solution to the flower-like ceria suspension, and then adding the second precipitant solution dropwise. In the present application, the flower-like CeO2 is preferably ultrasonically dispersed in water for 1-30 min, more preferably for 10 min, to obtain a flower-like CeO2 suspension. The above suspension is stirred at a speed of 100-500 rpm, more preferably at a speed of 200 rpm, and the stirring is maintained continuously. The transition metal nitrate solution is added, and the stirring is continued for 0.5-3 h to mix the solution uniformly. The stirring is maintained, and the second precipitant solution is added dropwise to the above suspension to perform a second co-precipitation reaction.

[0055] In the present application, the content of the flower-like CeO2 in the flower-like CeO2 suspension is 5-50 wt%, more preferably 20-30 wt%. The concentration of the transition metal nitrate solution is 0.01-0.5 mol / L, more preferably 0.02-0.3 mol / L. The concentration of the second precipitant solution is preferably 0.01-0.5 mol / L, more preferably 0.04-0.1 mol / L.

[0056] The amount of water used in the mixing of the flower-like ceria, the transition metal nitrate, the second precipitant and water in the present application satisfies the above-mentioned concentration ranges of the respective solutions.

[0057] In the present application, the temperature of the second co-precipitation reaction is preferably 0-60°C, more preferably 25-30°C. The time of the second co-precipitation reaction is preferably 0.5-6 h, more preferably 2-5 h.

[0058] After the second co-precipitation reaction is completed, the product obtained is preferably filtered, and the precipitate is collected by centrifugation. The precipitate is washed alternately with deionized water and ethanol, and is dried at 80-110°C for 12-36 h to obtain a flower-like CeO2 supported transition metal oxide precursor powder.

[0059] After the flower-like CeO2 supported transition metal oxide precursor is obtained, the flower-like CeO2 supported transition metal oxide precursor is subjected to a second calcination to obtain a flower-like CeO2 supported transition metal oxide.

[0060] In the present application, the temperature of the second calcination is preferably 500-600°C, and the holding time is preferably 1-4 h, more preferably 2-3 h. The temperature is raised to the temperature of the second calcination at a rate of 0.5-5°C / min, more preferably at a rate of 1-2°C / min. The second calcination is preferably performed in an air atmosphere.

[0061] After obtaining the ceria supported transition metal oxide, the ceria supported transition metal oxide is mixed with a binder, the obtained coating slurry is sprayed on the surface of the reticulated porous material, and drying and heat treatment are sequentially performed to obtain the flower-shaped ceria supported transition metal oxide catalytic coating-reticulated porous material.

[0062] In the present application, the binder preferably comprises an aluminum sol or a silicon sol; the mass ratio of the ceria supported transition metal oxide to the binder is 3:7-7:3, and more preferably 4:5.

[0063] In the present application, the material of the reticulated porous material preferably comprises silicon carbide, aluminum oxide or zirconium oxide; the present application does not have special limitations on the preparation method of the reticulated porous material, and the reticulated porous material can be prepared according to methods well known in the art.

[0064] In the embodiments of the present application, taking an aluminum oxide reticulated porous material as an example: using a polyurethane sponge as a template, an Al2O3 reticulated porous material is prepared by a slurry coating process:

[0065] 80wt% of plate brick corundum powder (325 mesh) and 20wt% of α-Al2O3 micro powder (<1.2μm) are placed in a stirring pot, and 1.5wt% of ammonium lignosulfonate, 0.4wt% of sodium carboxymethyl cellulose and 0.3wt% of polycarboxylate based on the total amount of the mixed powder are added to the mixed powder, and then deionized water is mixed, and after continuous stirring for 60min, an aluminum oxide slurry (solid content of 77.4wt%) is prepared, the polyurethane sponge template is immersed in the aluminum oxide slurry, and the excess slurry is squeezed out using a roller machine, the prepared green body is dried in a 110℃ oven, and after pre-burning at 1300℃ for 2h, an aluminum oxide porous ceramic preform is obtained; then, α-Al2O3 micro powder and deionized water are used as raw materials, and the impregnation slurry (solid content of 71.4wt%) is prepared by planetary ball milling for 3h; the above impregnation slurry is used to impregnate the aluminum oxide porous ceramic preform by vacuum impregnation for 0.5h, and then the sample is taken out and dried at 110℃, and then sintered at 1500℃ for 2h to obtain an aluminum oxide reticulated porous material with a size of 50*50*20mm and a pore size density of 10ppi.

[0066] The loading amount of the flower-shaped ceria supported transition metal oxide catalytic coating on the reticulated porous material is preferably 1-12wt%, and more preferably 5-8wt%.

[0067] After the coating slurry is sprayed on the surface of the reticulated porous material, the present application preferably performs drying at a temperature of 80-110℃ for 12-36h, and then performs heat treatment, and cools to room temperature in the furnace to obtain the flower-shaped ceria supported transition metal oxide catalytic coating-reticulated porous material.

[0068] In the present application, the temperature of the heat treatment is preferably 500-650 DEG C, more preferably 500-550 DEG C; the holding time is preferably 1-4 h, more preferably 1-2 h; and the temperature is raised to the temperature of the heat treatment at a rate of 0.5-3 DEG C / min (more preferably 1-2 DEG C / min).

[0069] The present application provides a flower-like CeO2 supported transition metal oxide catalytic coating-net-like porous material prepared by the preparation method.

[0070] The present application provides an application of the flower-like CeO2 supported transition metal oxide catalytic coating-net-like porous material in the field of porous medium ammonia combustion. The method for the application is not specially limited in the present application, and the application according to the method well known in the art is available.

[0071] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limitations to the protection scope of the present application.

[0072] In the following examples, the preparation of the alumina net-like porous material is as described above.

[0073] Example 1

[0074] 1) 21.72 g of cerium nitrate hexahydrate was dissolved in 500 mL of deionized water to obtain a cerium nitrate solution with a concentration of 0.1 mol / L, which was stirred at 0 DEG C; 11.86 g of ammonium bicarbonate was dissolved in 500 mL of deionized water to obtain an ammonium bicarbonate solution with a concentration of 0.3 mol / L, which was stirred at 0 DEG C; the above cerium nitrate solution was continuously stirred at 0 DEG C, and the ammonium bicarbonate solution was added dropwise into the cerium nitrate solution to obtain a precipitate solution, which was continuously stirred for 2 h, and then was left to stand at 0 DEG C for 6 h; the precipitate was collected by filtration and centrifugation, and was washed with deionized water and ethanol alternately; the precipitate was dried at 110 DEG C for 36 h to obtain a flower-like CeO2 precursor powder;

[0075] 2) The flower-like CeO2 precursor powder was placed in a muffle furnace, and was heated to 500 DEG C at a rate of 1 DEG C / min in an air atmosphere, and was kept at 500 DEG C for 2 h; the furnace was cooled to room temperature to obtain a flower-like CeO2 powder;

[0076] 3) Take 30 g of flower-like CeO2 powder into deionized water, control the content of flower-like CeO2 powder to be 20 wt%, ultrasonic dispersion for 10 min, prepare flower-like CeO2 suspension, stir the above suspension, the stirring speed is 200 rpm, keep the stirring state, add 100 mL of copper nitrate solution with a concentration of 0.2 mol / L (0.02 mol), continue to stir for 0.5 h to mix uniformly, keep the stirring state, add 100 mL of ammonium bicarbonate solution with a concentration of 0.4 mol / L (0.04 mol) into the above suspension dropwise, obtain a precipitation solution, keep stirring at 25°C for 5 h, collect the precipitate by filtration and centrifugation, clean the precipitate with deionized water and ethanol alternately, place it in a drying oven at 110°C for 36 h, and prepare flower-like CeO2 loaded transition metal oxide precursor powder;

[0077] 4) Put the above flower-like CeO2 loaded transition metal oxide precursor powder into a muffle furnace, heat it to 600°C at a rate of 2°C / min in an air atmosphere, keep the temperature for 2 h, cool the furnace to room temperature, and prepare flower-like CeO2 loaded transition metal oxide powder;

[0078] 5) Mix 20 g of the above flower-like CeO2 loaded transition metal oxide powder with 25 g of a binder (aluminum sol) to prepare coating slurry, spray the coating slurry onto the surface of an alumina reticular porous material (the pore size density is 10 ppi per 50*50*20 mm), dry the coating slurry at 110°C for 12 h after spraying, the loading amount of the coating on the reticular porous material is 8 wt%, heat it to 500°C at a rate of 1°C / min, keep the temperature for 1 h, cool the furnace to room temperature, and obtain flower-like CeO2 loaded transition metal oxide catalytic coating-alumina reticular porous material.

[0079] Example 2

[0080] The difference from Example 1 is that in step 3), copper nitrate solution and manganese nitrate solution with a concentration of 0.2 mol / L are respectively configured, copper nitrate solution and manganese nitrate solution are mixed according to a copper:manganese molar ratio of 1:1 to obtain a copper-manganese mixed solution, and the copper-manganese two kinds of metal salt total moles are 0.02 mol.

[0081] Example 3

[0082] The difference from Example 1 is that in step 3), copper nitrate solution, manganese nitrate solution and cobalt nitrate solution with a concentration of 0.2 mol / L are respectively configured, the three kinds of solutions are mixed according to a copper:manganese: cobalt molar ratio of 1:1:1 to obtain a copper-manganese-cobalt mixed solution, and the copper-manganese-cobalt three kinds of metal salt total moles are 0.02 mol.

[0083] Characterization and testing

[0084] Figure 1 SEM image of the flower-like CeO2 powder prepared in Example 1 of the present application; from Figure 1 It can be seen that the prepared powder presents a flower-like structure, the particle size distribution is uniform, and there are pores inside the flower-like particles and between the flower-like particles, forming a multi-layered porous structure. This structure is beneficial to improve the absorption and emission of infrared waves in the final coating, thus improving the infrared emissivity and the high-temperature radiation performance of the porous medium.

[0085] Figure 2 SEM image of the flower-like CeO2 supported copper oxide powder prepared in Example 1 of the present application; from Figure 2 It can be seen that the copper oxide presents sub-micron particles, which are well dispersed and supported on the flower-like CeO2 particles.

[0086] Figure 3 SEM image of the flower-like CeO2 supported copper and manganese oxide powder prepared in Example 2 of the present application; from Figure 3 It can be seen that the copper and manganese oxides present micron particles, which are supported on the flower-like CeO2 particles.

[0087] Figure 4 SEM image of the fracture section of the flower-like CeO2 supported transition metal oxide catalytic coating-meshed porous material prepared in Example 1 of the present application; from Figure 4 It can be seen that the coating is well combined with the skeleton, and the coating presents a porous structure.

[0088] Test Example

[0089] The prepared material was placed in a porous medium burner for combustion evaluation, and the specific test was as follows:

[0090] NO x Test conditions: The prepared material was placed in a porous medium burner, and the test conditions were that the ammonia flow was 4.21 NL / min, the air flow was adjusted to control the equivalence ratio of ammonia and air to be 0.8-1.5, and the tail gas NO x emission was measured.

[0091] Heating efficiency test: A beaker containing pure water was placed directly above the porous medium burner, and the change of water temperature with time was monitored to determine the heating efficiency of the burner.

[0092] The results showed that:

[0093] The flower-like CeO2 supported transition metal oxide coating-meshed porous material prepared in Example 1 was detected: the mid-infrared emissivity of the flower-like CeO2 supported transition metal oxide powder was as high as 91%, the specific surface area was 92.7 m 2 / g, with high active oxygen content (O active / (O active +O lattice ) = 54.8%. The radiation efficiency of the porous medium burner at a combustion temperature of 1000-1200°C is 80-83%, the heating efficiency of the porous medium burner is 39-40°C / min, and the NO x emission of the porous medium burner is reduced from 8000-10000 ppm to meet the national NO x emission standard (30 mg / m 3 or less).

[0094] The porous medium ammonia combustion flower-like CeO2 supported transition metal oxide coating-net-like porous material prepared in Example 2 was detected: the radiation efficiency of the porous medium burner at a combustion temperature of 900-1000°C is 85-88%, the heating efficiency of the porous medium burner is 39-41°C / min, and the NO x emission of the porous medium burner is reduced from 8000-10000 ppm to meet the national NO x emission standard (30 mg / m 3 or less).

[0095] The porous medium ammonia combustion flower-like CeO2 supported transition metal oxide coating-net-like porous material prepared in Example 3 was detected: the radiation efficiency of the porous medium burner at a combustion temperature of 800-900°C is 88-92%, the heating efficiency of the porous medium burner is 40-43°C / min, and the NO x emission of the porous medium burner is reduced from 8000-10000 ppm to meet the national NO x emission standard (30 mg / m 3 or less).

[0096] The above is only a preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can also make several improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. Use of a flower-like CeO2 supported transition metal oxide catalytic coating- reticulated porous material in the field of porous media ammonia combustion, characterized in that, The preparation method of the flower-like CeO2 supported transition metal oxide catalytic coating-net porous material comprises the following steps: Mixing cerium salt, first precipitant and water, carrying out first coprecipitation reaction to obtain flower-like cerium dioxide precursor; Carrying out first calcination on the flower-like cerium dioxide precursor to obtain flower-like cerium dioxide; Mixing the flower-like cerium dioxide, transition metal nitrate, second precipitant and water, carrying out second coprecipitation reaction to obtain cerium dioxide supported transition metal oxide precursor; Carrying out second calcination on the cerium dioxide supported transition metal oxide precursor to obtain cerium dioxide supported transition metal oxide; Mixing the cerium dioxide supported transition metal oxide and binder, spraying the obtained coating slurry on the surface of the net porous material, and sequentially carrying out drying and heat treatment to obtain the flower-like CeO2 supported transition metal oxide catalytic coating-net porous material. The transition metal nitrate comprises one or more of copper nitrate, manganese nitrate, cobalt nitrate, iron nitrate and nickel nitrate.

2. Use according to claim 1, characterized in that, The cerium salt comprises cerium nitrate; the first precipitant comprises ammonium bicarbonate, ammonium carbonate, sodium carbonate or sodium bicarbonate; and the molar ratio of the first precipitant to the cerium salt is 1-5:

1.

3. Use according to claim 2, characterized in that, The step of mixing the cerium salt, first precipitant and water comprises the following steps: mixing the cerium salt with water to obtain cerium salt solution, mixing the first precipitant with water to obtain first precipitant solution, and dropping the first precipitant solution into the cerium salt solution; the concentration of the cerium salt solution is 0.01-0.5 mol / L, and the concentration of the first precipitant solution is 0.01-0.5 mol / L. The temperature of the first coprecipitation reaction is 0-80 DEG C, and the time is 0.1-8 h.

4. Use according to claim 3, characterized in that, The temperature of the first calcination is 500-600 DEG C, the holding time is 1-4 h, and the temperature is raised to the temperature of the first calcination at a rate of 0.5-5 DEG C / min.

5. The use according to claim 1, characterized in that, The second precipitant comprises ammonium bicarbonate, ammonium carbonate, sodium carbonate or sodium bicarbonate.

6. The application according to claim 1 or 5, characterized in that, The use amount ratio of the flower-like cerium dioxide, transition metal nitrate and second precipitant is (10-100) g:(0.01-0.1) mol:(0.01-0.1) mol; and the molar ratio of the second precipitant to the transition metal nitrate is (1-5):

1. The step of mixing the flower-like cerium dioxide, transition metal nitrate, second precipitant and water comprises the following steps: dispersing the flower-like cerium dioxide in water to obtain flower-like cerium dioxide suspension; mixing the transition metal nitrate with water to obtain transition metal nitrate solution, mixing the second precipitant with water to obtain second precipitant solution; adding the transition metal nitrate solution into the flower-like cerium dioxide suspension, and then dropping the second precipitant solution; the content of flower-like CeO2 in the flower-like cerium dioxide suspension is 5-50 wt%; the concentration of the transition metal nitrate solution is 0.01-0.5 mol / L, and the concentration of the second precipitant solution is 0.01-0.5 mol / L.

7. Use according to claim 6, characterized in that, The temperature of the second co-precipitation reaction is 0-60 DEG C, and the time is 0.5-6h; the temperature of the second calcination is 500-600 DEG C, and the holding time is 1-4h, and the temperature is raised to the temperature of the second calcination at a rate of 0.5-5 DEG C / min.

8. The use according to claim 1, characterized in that, The material of the netted porous material includes silicon carbide, alumina or zirconia; The temperature of the heat treatment is 500-650 DEG C, and the holding time is 1-4h; the temperature is raised to the temperature of the heat treatment at a rate of 0.5-3 DEG C / min.

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