Preparation method of pickering type scr catalytic functional emulsion containing composite metal oxide particles

Abstract

The application provides a preparation method of a Pickering type SCR catalytic functional emulsion containing composite metal oxide particles. The composite metal oxide particles prepared by a wet chemical method are used as emulsifiers, water is used as a continuous phase, and a water-insoluble organic solvent is used as a dispersed phase. The stable O / W type catalytic functional emulsion is obtained by high-speed shearing homogenization and emulsification in a sealed container. The composite metal oxide nanoparticles with no irritation, high low-temperature catalytic activity and easily available raw materials are used as the SCR catalyst and emulsifier to replace the traditional surfactant. The Pickering type SCR catalytic functional emulsion prepared by the application has better dispersion performance and stability than the catalytic functional emulsion stabilized by the traditional surfactant. The preparation method is simple, the prepared emulsion can be uniformly loaded on the surface of various filter carriers, the reaction activity of the catalyst is well reserved, and the binding firmness between the catalyst and the filter carrier is high.

Description

Technical Field

[0001] This invention relates to the field of high-temperature flue gas SCR catalytic denitrification, specifically to a method for preparing a Pickering-type SCR catalytic functional emulsion containing composite metal oxide particles. Background Technology

[0002] The main pollutants emitted from flue gas include sulfur oxides, nitrogen oxides, and highly toxic substances such as dioxins and trace heavy metals such as Cr and Hg contained in fly ash. To effectively control air pollutant emissions, a series of new flue gas denitrification technologies have been developed after years of research, such as high-temperature, medium-temperature, and low-temperature SCR denitrification technologies, and SNCR denitrification technologies. By loading SCR denitrification catalysts onto dust collector filter media and integrating SCR denitrification technology into baghouse dust collectors, an integrated SCR denitrification and dust removal technology is formed. This technology can solve technical problems such as high investment costs for denitrification equipment, easy clogging of catalysts by dust, catalyst wear and even poisoning and failure, and NH3 escape, achieving short-process, low-cost operation for integrated dust and nitrogen removal. Currently, the main method for combining denitrification catalysts and filter bags in industrial production is the impregnation method. The loading process involves adding surfactants to an aqueous dispersion of the denitrification catalyst to prepare a catalytic functional emulsion. The filter material is then impregnated into the emulsion, and the catalyst is loaded under capillary force. Compared with other loading methods, this method is simpler and more economical, but it still has problems such as uneven dispersion of the loaded catalyst on the surface of the filter material and poor adhesion strength.

[0003] Pickering emulsions are a class of emulsions stabilized by nano / micron-sized solid particles. They possess excellent stability, resistance to aggregation, flocculation, and austenitization, making them widely applicable in the food, cosmetics, and pharmaceutical industries. Compared to small-molecule surfactants and traditional emulsions stabilized by natural macromolecules, the adsorption process of the solid particles acting as emulsifiers at the water-oil interface in Pickering emulsions is irreversible. This is because the particles not only reduce the total free energy of the system but also provide a spatial physical barrier for the contact between droplets, giving Pickering emulsions greater stability. This eliminates the adverse effects of surfactants used in traditional emulsions, such as foaming, air trapping, biological interactions, or irritation.

[0004] Metal oxide particles, such as nano-manganese dioxide, iron oxide, and copper oxide, have been widely studied and applied in the field of low-temperature denitrification due to their rich variable valence states, excellent low-temperature redox capabilities in NH3-SCR reactions, and abundant oxygen vacancies.

[0005] This invention uses composite metal oxide particles as emulsifiers and SCR catalysts to stably form Pickering emulsions with SCR catalytic function. This emulsion is then combined with filter materials, which can improve the problems of uneven dispersion and poor adhesion strength of catalytic emulsions prepared by the traditional surfactant method when loaded onto the filter material surface, thereby improving the dispersion and loading strength of the catalyst on the filter material surface. Summary of the Invention

[0006] In view of the defects and shortcomings of existing methods for preparing catalytic emulsions using surfactants and the process of loading filter media, the purpose of this invention is to provide a method for preparing a Pickering-type SCR catalytic functional emulsion containing composite metal oxide particles. This method can effectively solve the problems of short stabilization time and poor dispersibility of catalytic emulsions prepared with traditional surfactants, as well as poor dispersion uniformity and low loading strength after loading filter media.

[0007] Another object of the present invention is to provide a Pickering-type SCR catalytic functional emulsion containing composite metal oxide particles prepared by the above method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing a Pickering-type SCR catalytic functional emulsion containing composite metal oxide particles, comprising the following steps:

[0010] (1) Preparation of composite metal oxide nanoparticle dispersion: The composite metal oxide particles were prepared by wet chemical method, which included: weighing two or more metal oxide particles and ultrasonically dispersing them in deionized water; then adding a certain proportion of anhydrous ethanol and mixing them evenly, drying them in air at 120°C for 2-4 hours to remove excess water; finally, heating the dried block to 300°C at a heating rate of 10°C / min and stabilizing it for 2-3 hours for sintering; after the material cooled to room temperature, grinding it, adding a certain mass proportion of deionized water, and ultrasonically dispersing it to obtain the composite metal oxide particle dispersion.

[0011] (2) Preparation of Pickering catalytic functional emulsion: The above-mentioned composite metal oxide particle dispersion was mixed with the oil phase, and homogenized by high-speed shearing. Then, a certain amount of PTFE aqueous dispersion was added and mixed to obtain a Pickering type SCR catalytic functional emulsion containing composite metal oxide particles.

[0012] The composite metal oxide particles mentioned in step (1) are prepared from two or more of the following: nano MnO2, nano CeO2, nano Fe2O3, nano CuO, Ti-Ce-Zr-Ox (molar ratio Ti:Ce:Zr = 10:1:1), CuMn / TiO2 (molar ratio Mn:Cu = 2:1), Mn-Co-Ce / TiO2 (molar ratio Mn:Co:Ce = 2:1:1), and Fe2O3-MnO2-CeO2 / TiO2 (molar ratio Fe:Mn:Ce = 1:5:1). The proportion of Mn element in the metal oxide must be >2wt%, and the particle size of the metal oxide particles is 100-500nm. The volume ratio of anhydrous ethanol to deionized water is 1:(1-10).

[0013] The ultrasonic dispersion power of the metal nanoparticles in step (1) in deionized water is 30-120W, and the time is 0.2-0.5h; the ultrasonic dispersion power of the composite metal oxide particle dispersion after sintering and grinding is 100-300W, and the time is 0.5-1h, wherein the particle size of the composite metal oxide particles after grinding is 100-500nm; the mass percentage concentration of solid particles in the obtained composite metal oxide particle dispersion is 1%-20%, and the particle size of the dispersed particles is 1-100μm.

[0014] The oil phase mentioned in step (2) is one of dimethyl silicone oil (viscosity coefficient 500-1000 mPa.s), dichloromethane, toluene, n-dodecane, n-hexane and cyclopentadimethylsiloxane. Except for dimethyl silicone oil, all the above reagents are analytical grade. The volume ratio of the composite metal oxide particle dispersion to the oil phase is 1:(0.05~0.2).

[0015] The high-speed shear rate mentioned in step (2) is 5,000 to 20,000 rpm / min, the processing time is 2 to 10 min; the solid content of PTFE water dispersion is 10 wt% to 60 wt%, the average particle size is 0.1 to 1 μm, and the mass ratio of PTFE to composite metal oxide particles is (0.2 to 4.0):1.

[0016] The present invention provides a Pickering-type SCR catalytic functional emulsion containing composite metal oxide particles prepared by the preparation method described above. The emulsion type is oil-in-water (O / W) and the droplet particle size is 1-100 μm.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The preparation process of this invention is simple, green and safe. Using composite metal oxide particles as raw materials, it ensures excellent denitrification performance, has low preparation cost, and is easy to scale up for production. The stability and dispersibility of the Pickering-type SCR catalytic functional emulsion can be controlled by adjusting the concentration of composite metal oxide particles, the water-oil volume ratio, and the amount of PTFE dispersion added.

[0019] In the Pickering-type SCR catalytic functional emulsion containing composite metal oxide particles prepared by this invention, under the influence of oil-water interfacial tension and the hydrophilic and hydrophobic properties of solid particles, the composite metal oxide particles can stably exist on the oil-water interface, coating the oil phase droplets to form an O / W type Pickering emulsion. It has good stability and dispersibility and is not prone to aggregation. It can be stored for a long time without demulsification. It can replace the use of small molecule surfactants in the preparation of traditional SCR catalytic emulsions, reducing the harm to the environment and human health. It has a good application prospect in the field of denitrification catalytic filter media loading.

[0020] This invention utilizes the unique reducing properties and oxygen storage and release capabilities of nano-cerium dioxide, which exhibit a synergistic effect when combined with manganese dioxide. The loading of Mn can block the reaction of NH3 and Ce. 4+ Direct contact with Ce reduces Ce 4+ The oxidation of NH3 is more conducive to improving catalytic activity. Using composite metal oxide particles as emulsifiers and SCR catalysts, a Pickering emulsion with SCR catalytic function is stably formed. Combining this with filter materials can improve the problems of uneven dispersion and poor adhesion strength of catalytic emulsions prepared by the traditional surfactant method on the filter material surface, and improve the dispersion and loading strength of the catalyst on the filter material surface. Attached Figure Description

[0021] Figure 1-1 and Figure 1-2 The images show the initial state of the Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2 particles prepared in Example 1, and its appearance and droplet microscopic images after the emulsion has been left to stand for 30 days.

[0022] Figure 2-1 and Figure 2-2 The images show the initial state of the SCR catalytic functional emulsion (control group) prepared by the conventional surfactant method in Example 1, and the appearance and droplet micrographs of the emulsion after standing for 30 days.

[0023] Figure 3The droplet size distribution curves of the Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2 particles prepared in Example 1 (experimental group) and the corresponding SCR catalytic functional emulsion prepared by the surfactant method (control group) are shown in the initial state after preparation and after the emulsion has been left to stand for 30 days.

[0024] Figure 4-1 and Figure 4-2 The figures show a comparison of the catalyst dispersion after the Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2 particles prepared in Example 1 (experimental group) and the corresponding SCR catalytic functional emulsion prepared by the surfactant method (control group) were loaded onto the filter media.

[0025] Figure 5-1 and Figure 5-2 The figures show a comparison of the catalytic denitrification efficiency and loading stability of the Pickering-type SCR catalytic functional emulsion (experimental group) prepared in Examples 1-6 and the SCR catalytic functional emulsion prepared by the traditional surfactant method (control group) after loading filter media.

[0026] Figure 6 This is a flowchart for the preparation of Pickering-type SCR catalytic functional emulsions. Detailed Implementation

[0027] The embodiments of the present invention are described in detail below. These embodiments are intended to explain the present invention and should not be construed as limiting the present invention. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0028] Example 1: A Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2 particles, the preparation process of which is as follows:

[0029] 5.0g of nano CeO2 particles and 2.0g of nano MnO2 particles were placed in 10mL of deionized water and ultrasonically dispersed at 30W for 0.2h. Then, 10mL of ethanol was added and mixed evenly. The mixture was dried at 120℃ in air for 2h to remove excess moisture. Finally, the remaining dried lumps were heated to 300℃ at a heating rate of 10℃ / min and stabilized for 2h for sintering. After the material cooled to room temperature, it was ground to 100nm. 0.5g of the composite MnO2-CeO2 particles prepared above were weighed and added to 50mL of deionized water. The mixture was ultrasonically dispersed at 100W for 0.5h to obtain a composite MnO2-CeO2 particle dispersion.

[0030] The above-mentioned composite MnO2-CeO2 particle dispersion was mixed with 0.25 mL of n-dodecane and homogenized and sheared for 2 min at 5000 rpm / min. Then, 1 mL of PTFE aqueous dispersion with a solid content of 10 wt% and an average particle size of 0.1 μm was added and mixed evenly to obtain a Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2 particles.

[0031] Example 2: A Pickering-type SCR catalytic functional emulsion containing composite MnO2-Fe2O3 particles, the preparation process of which is as follows:

[0032] 10.0g of nano Fe2O3 particles and 4.0g of nano MnO2 particles were placed in 50mL of deionized water and ultrasonically dispersed at 120W for 0.2h. Then, 20mL of ethanol was added and mixed evenly. The mixture was dried at 120℃ in air for 4h to remove excess moisture. Finally, the remaining dried lumps were heated to 300℃ at a heating rate of 10℃ / min and stabilized for 4h for sintering. After the material cooled to room temperature, it was ground to 500nm. 10g of the above-prepared composite MnO2-Fe2O3 particles were weighed and added to 50mL of deionized water. The mixture was ultrasonically dispersed at 300W for 1h to obtain a composite MnO2-Fe2O3 particle dispersion.

[0033] The above-mentioned composite MnO2-Fe2O3 particle dispersion was mixed with 10 mL of n-dodecane and homogenized and sheared for 10 min at 20000 rpm / min. Then, 7.3 mL of PTFE aqueous dispersion with a solid content of 60 wt% and an average particle size of 1 μm was added and mixed evenly to obtain a Pickering-type SCR catalytic functional emulsion containing composite MnO2-Fe2O3 particles.

[0034] Example 3: A Pickering-type SCR catalytic functional emulsion containing composite MnO2-CuO particles, the preparation process of which is as follows:

[0035] 6.0g of nano-CuO particles and 3.0g of nano-MnO2 particles were placed in 50mL of deionized water and ultrasonically dispersed at 80W for 0.3h. Then, 10mL of ethanol was added and mixed evenly. The mixture was dried at 120℃ in air for 3h to remove excess moisture. Finally, the remaining dried lumps were heated to 300℃ at a heating rate of 10℃ / min and stabilized for 2.5h for sintering. After the material cooled to room temperature, it was ground to 300nm. 5g of the above-prepared composite MnO2-CuO particles were weighed and added to 50mL of deionized water. The mixture was ultrasonically dispersed at 200W for 0.8h to obtain a composite MnO2-CuO particle dispersion.

[0036] The above-mentioned composite MnO2-CuO particle dispersion was mixed with 5 mL of n-dodecane and homogenized and sheared for 6 min at 15000 rpm / min. Then, 14.6 mL of PTFE aqueous dispersion with a solid content of 30 wt% and an average particle size of 0.5 μm was added and mixed evenly to obtain a Pickering-type SCR catalytic functional emulsion containing composite MnO2-CuO particles.

[0037] Example 4: A Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2-Fe2O3 particles, the preparation process of which is as follows:

[0038] 5.0g of nano CeO2 particles, 2.5g of nano Fe2O3 particles, and 2.5g of nano MnO2 particles were placed in 50mL of deionized water and ultrasonically dispersed at 100W for 0.4h. Then, 30mL of ethanol was added and mixed evenly. The mixture was dried at 120℃ in air for 4h to remove excess moisture. Finally, the remaining dried lumps were heated to 300℃ at a heating rate of 10℃ / min and stabilized for 2h for sintering. After the material cooled to room temperature, it was ground to 400nm. 5g of the above-prepared composite MnO2-CeO2-Fe2O3 particles were weighed and added to 50mL of deionized water. The mixture was ultrasonically dispersed at 200W for 0.7h to obtain a composite MnO2-CeO2-Fe2O3 particle dispersion.

[0039] The above-mentioned composite MnO2-CeO2-Fe2O3 particle dispersion was mixed with 10 mL of n-dodecane and homogenized and sheared at 12000 rpm / min for 6 min. Then, 7.5 mL of PTFE aqueous dispersion with a solid content of 40 wt% and an average particle size of 0.2 μm was added and mixed evenly to obtain a Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2-Fe2O3 particles.

[0040] Example 5: A Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2-CuO particles, the preparation process of which is as follows:

[0041] 5.0g of nano CeO2 particles, 2.5g of nano CuO particles, and 2.5g of nano MnO2 particles were placed in 50mL of deionized water and ultrasonically dispersed at 80W for 0.5h. Then, 25mL of ethanol was added and mixed evenly. The mixture was dried at 120℃ in air for 4h to remove excess moisture. Finally, the remaining dried lumps were heated to 300℃ at a heating rate of 10℃ / min and stabilized for 2h for sintering. After the material cooled to room temperature, it was ground to 500nm. 5g of the above-prepared composite MnO2-CeO2-CuO particles were weighed and added to 50mL of deionized water. The mixture was ultrasonically dispersed at 250W for 0.6h to obtain a composite MnO2-CeO2-CuO particle dispersion.

[0042] The above-mentioned composite MnO2-CeO2-CuO particle dispersion was mixed with 10 mL of n-dodecane and homogenized and sheared for 6 min at 12000 rpm / min. Then, 7.5 mL of PTFE aqueous dispersion with a solid content of 50 wt% and an average particle size of 0.3 μm was added and mixed evenly to obtain a Pickering-type SCR catalytic functional emulsion containing composite MnO2-CeO2-CuO particles.

[0043] Example 6: A Pickering-type SCR catalytic functional emulsion containing composite MnO2-Fe2O3-CuO particles, the preparation process of which is as follows:

[0044] 5.0g of nano Fe2O3 particles, 2.5g of nano CuO particles, and 2.5g of nano MnO2 particles were placed in 50mL of deionized water and ultrasonically dispersed at 100W for 0.4h. Then, 30mL of ethanol was added and mixed evenly. The mixture was dried at 120℃ in air for 3h to remove excess moisture. Finally, the remaining dried lumps were heated to 300℃ at a heating rate of 10℃ / min and stabilized for 3h for sintering. After the material cooled to room temperature, it was ground to 500nm. 5g of the above-prepared composite MnO2-Fe2O3-CuO particles were weighed and added to 50mL of deionized water and ultrasonically dispersed at 200W for 0.6h to obtain a composite MnO2-Fe2O3-CuO particle dispersion.

[0045] The above-mentioned composite MnO2-Fe2O3-CuO particle dispersion was mixed with 8 mL of n-dodecane and homogenized and sheared at 16000 rpm / min for 6 min. Then, 7 mL of PTFE aqueous dispersion with a solid content of 60 wt% and an average particle size of 0.2 μm was added and mixed evenly to obtain a Pickering-type SCR catalytic functional emulsion containing composite MnO2-Fe2O3-CuO particles.

[0046] Example 7: A Pickering-type SCR catalytic functional emulsion-supported filter material containing composite metal oxide particles degrades nitrogen oxides. The process is as follows:

[0047] To investigate the catalytic denitrification activity of the obtained Pickering-type SCR catalytic functional emulsion, the Pickering emulsions prepared in Examples 1-6 were used to catalytically degrade NO on supported filter media. X Experiment. The specific experimental procedure is as follows: The original substrate filter media was cut into pieces with a diameter of about 7 cm, placed in a beaker containing deionized water, and ultrasonically cleaned for 15 minutes to remove fine particles and grease from the surface and internal pores of the filter media. It was then dried in a 200℃ oven for 2 hours, followed by drying in a vacuum drying oven at 120℃ to remove internal moisture. The weight was recorded. Using the Pickering-type SCR catalytic functional emulsions prepared in Examples 1-6, the filter media were immersed and repeatedly turned, stirred and impregnated with a mechanical stirrer for 3 hours, and then allowed to stand for 3 hours to load the impregnation. The filter media were then removed and dried in a vacuum drying oven at 160℃ to obtain the catalytic filter media prepared by the impregnation method. The above catalytic filter media were tested for nitrogen oxide removal performance using a fixed-bed denitrification performance evaluation device to evaluate the catalytic denitrification activity of the prepared Pickering-type SCR catalytic functional emulsion. This was used as the experimental group. The NOx removal efficiency of the catalytic filter media was measured using... This can be defined as the ratio of the difference between the NO concentration at the catalytic reaction inlet and the NO concentration in the exhaust gas at the outlet to the inlet NO concentration. The calculation formula is as follows:

[0048]

[0049] Wherein, NOin is the NO concentration (ppm) at the inlet of the fixed-bed reactor; NOout is the NO concentration (ppm) at the outlet of the fixed-bed reactor.

[0050] Example 8: Evaluation of the catalyst loading effect of a Pickering-type SCR catalytic emulsion-supported filter media containing composite metal oxide particles. The process is as follows:

[0051] To investigate the loading strength of the catalyst on the filter media after loading the Pickering-type SCR catalytic functional emulsion, the loading strength of the catalyst on the filter media was tested using the Pickering emulsions prepared in Examples 1-6. The specific testing procedure is as follows: The catalytic filter media samples were tested using a Martindale abrasion tester, and the test procedure followed GB / T 21196.3-2007. All samples were tested in parallel three times, and the average weight was taken. The formula for calculating the loading strength of the samples is as follows:

[0052]

[0053] Wherein, loading firmness refers to the load firmness, i.e. the mass retention rate (%) of the catalytic filter material sample before and after the test; m before wear refers to the mass (g) of the catalytic filter material sample before wear; and m after wear refers to the mass (g) of the catalytic filter material sample after wear.

[0054] The SCR catalytic functional emulsion-supported filter material prepared using the traditional surfactant method will be used to catalyze the degradation of NO. X A catalyst loading stability test was conducted as a control group. The specific experimental procedure is as follows: A certain mass of composite metal oxide particles was taken and placed in a 100 mL centrifuge tube. 50 mL of deionized water was added, and the particles were thoroughly ultrasonically dispersed to obtain a metal oxide nanoparticle dispersion. A certain mass of C was added... 12-14 A dispersion of secondary alcohol polyoxyethylene ether and PTFE in water was manually shaken for 3 minutes to obtain an SCR catalytic functional emulsion stabilized by a surfactant (control group corresponding to the emulsion in Example 1: 0.5 g of composite MnO2-CeO2 particles were weighed, C...). 12-14 The secondary alcohol polyoxyethylene ether had a mass of 0.05 g, and the PTFE aqueous dispersion had a volume of 1 mL; the control group corresponding to the emulsion in Example 2: the composite MnO2-Fe2O3 particles had a mass of 10 g, C 12-14 The secondary alcohol polyoxyethylene ether had a mass of 1g, and the PTFE aqueous dispersion had a volume of 7.3mL; the control group corresponding to the emulsion in Example 3: the composite MnO2-CuO particles had a mass of 5g, C 12-14 The secondary alcohol polyoxyethylene ether had a mass of 0.5 g, and the PTFE aqueous dispersion had a volume of 14.6 mL; the control group corresponding to the emulsion in Example 4: the composite MnO2-CeO2-Fe2O3 particles had a mass of 5 g, C 12-14 The secondary alcohol polyoxyethylene ether had a mass of 0.5 g, and the PTFE aqueous dispersion had a volume of 7.5 mL; the control group corresponding to the emulsion in Example 5: the composite MnO2-CeO2-CuO particles had a mass of 5 g, C 12-14 The secondary alcohol polyoxyethylene ether had a mass of 0.5 g, and the PTFE aqueous dispersion had a volume of 7.5 mL; the control group corresponding to the emulsion in Example 6: the composite MnO2-Fe2O3-CuO particles had a mass of 5 g, C 12-14 The mass of secondary alcohol polyoxyethylene ether was 0.5 g, and the volume of PTFE aqueous dispersion was 7 mL. The process of testing the emulsion-loaded filter media, nitrogen oxide removal performance, and catalyst loading effect was the same as in Examples 7-8, and other experimental conditions were also kept consistent.

[0055] Figure 2-1 and Figure 2-2The images show the initial state and droplet microstructure of the SCR catalytic functional emulsion (control group) prepared by the conventional surfactant method in Example 1, after preparation, and after standing for 30 days. Droplet size distribution curves for the experimental and control groups were obtained using a laser particle size analyzer. Figure 3 The average droplet size (Table 1) shows that, compared with the SCR catalytic functional emulsion prepared by the surfactant method, the Pickering-type SCR catalytic functional emulsion exhibits a dispersion state similar to the initial state after standing for 30 days. Although the droplet size increases slightly, the overall stability of the emulsion is better, indicating that long-term storage of the emulsion will not destroy the stability of the SCR catalytic functional emulsion itself. On the other hand, the SCR catalytic functional emulsion prepared by the surfactant method shows a significant difference in dispersion state from the initial state after standing for 30 days. The emulsion exhibits obvious stratification, and the average droplet size test results also show a significant increase in the emulsion droplet size, indicating that the control group emulsion has poor stability and is not suitable for long-term storage and use.

[0056] Table 1 Comparison of droplet sizes of SCR catalytic functional emulsions prepared by different methods

[0057]

[0058] Table 2 compares the denitrification efficiency of the Pickering-type SCR catalytic functional emulsion (experimental group) containing composite MnO2-CeO2 particles prepared in Example 1, loaded onto filter media, with that of the same mass of composite MnO2-CeO2 particles at the same reaction temperature. It can be seen that under the same reaction conditions, the denitrification efficiency of the Pickering-type SCR catalytic functional emulsion (experimental group) loaded onto filter media is basically close to that of the composite MnO2-CeO2 particles, both exceeding 80%. This indicates that the Pickering-type SCR catalytic functional emulsion prepared with composite MnO2-CeO2 particles does not affect the catalytic performance of the composite MnO2-CeO2 particles themselves, and has broad application prospects in the field of catalytic degradation.

[0059] Table 2. Comparison of denitrification efficiency between composite MnO2-CeO2 particles and Pickering-type SCR catalytic emulsion containing composite MnO2-CeO2 particles (experimental group)

[0060]

[0061]

[0062] Figure 4-1 and Figure 4-2The figures show a comparison of the catalyst dispersion after loading the Pickering-type SCR catalytic functional emulsion (experimental group) prepared in Example 1 and the corresponding SCR catalytic functional emulsion prepared by the surfactant method (control group) onto the filter media. It can be observed that, compared to the SCR catalytic functional emulsion prepared by the surfactant method, the Pickering-type SCR catalytic functional emulsion, after loading the filter media, forms a dense and uniformly distributed catalyst layer on the surface of the filter media fibers. Although many raised agglomerated particles are observed adhering to the fiber surface, there is no obvious pore blockage, and the original three-dimensional network structure of the filter media fibers is basically maintained. This is more conducive to the full contact between the reactant gas and the catalytic filter media, promoting the forward SCR catalytic reaction, and does not significantly affect the gas permeability and filtration performance of the filter media itself. In contrast, after loading the filter media with the SCR catalytic functional emulsion prepared by the surfactant method in the control group, the catalyst agglomerates into small pieces, forming blockages between the pores of the filter media fibers, and a large portion of the fiber surface does not form a dense catalyst layer.

[0063] Figure 5-1 and Figure 5-2 The figures show a comparison of the catalytic denitrification efficiency and loading strength of the Pickering-type SCR catalytic functional emulsion (experimental group) prepared in Examples 1-6 and the SCR catalytic functional emulsion prepared by the traditional surfactant method (control group) after loading filter media. It can be seen that compared with the SCR catalytic functional emulsion prepared by the surfactant method, the Pickering-type SCR catalytic functional emulsion, after loading filter media, exhibits higher denitrification efficiency and loading strength due to its more uniform loading and dispersion. At 210℃, the improvement in both denitrification efficiency and loading strength is approximately 10%. The results indicate that the Pickering-type SCR catalytic functional emulsion prepared in this invention can significantly enhance the denitrification reactivity and loading strength of the catalytic filter media, improving the problems of uneven catalyst dispersion and poor adhesion strength on the filter media surface after loading filter media with the SCR catalytic functional emulsion prepared by the traditional surfactant method.

[0064] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a Pickering-type SCR catalytic functional emulsion containing composite metal oxide particles, characterized in that, The method includes the following steps: (1) Take 5.0 g of nano CeO2 particles and 2.0 g of nano MnO2 particles and put them into 10 mL of deionized water and ultrasonically disperse them at 30 W ultrasonic power for 0.2 h. Then add 10 mL of ethanol and mix evenly. Dry them in air atmosphere at 120 ℃ for 2 h to remove excess water. Finally, heat the remaining dried block to 300 ℃ at a heating rate of 10 ℃ / min and stabilize it for 2 h for sintering. After the material cools to room temperature, grind it to 100 nm. Weigh 0.5 g of the above-prepared composite MnO2-CeO2 particles and add them to 50 mL of deionized water. Ultrasonically disperse them at 100 W power for 0.5 h to obtain composite MnO2-CeO2 particle dispersion. (2) The above-mentioned composite MnO2-CeO2 particle dispersion was mixed with 0.25 mL of n-dodecane and homogenized and sheared for 2 min at 5000 rpm / min. Then, 1 mL of PTFE aqueous dispersion with a solid content of 10 wt% and an average particle size of 0.1 μm was added and mixed evenly to obtain a Pickering type SCR catalytic functional emulsion containing composite MnO2-CeO2 particles. The initial particle size of the emulsion droplets was 1.5 μm, and the particle size after standing for 30 days was 5.5 μm.

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