Core-shell layered manganese-cerium-based bifunctional catalyst as well as preparation method and application thereof

Abstract

The invention relates to a core-shell layered manganese-cerium-based bifunctional catalyst and a preparation method and application thereof, and belongs to the technical field of environmental catalytic materials.The preparation method comprises the steps that manganese nitrate and cerium nitrate are dissolved in deionized water according to the molar ratio, a template agent is added, and stirring is conducted to form a homogeneous solution; dropwise adding ammonia water to adjust the pH value to be alkaline to generate manganese-cerium hydroxide coprecipitation; after standing and aging, centrifugally washing and drying to obtain precursor powder; calcining the precursor powder in an air atmosphere to obtain a manganese-cerium solid solution; dispersing the manganese-cerium solid solution in ethanol, adding cerium nitrate and diammonium hydrogen phosphate, adjusting the pH value, and stirring in a water bath to form CePO4 precursor sol; drying the sol to obtain a shell precursor; dispersing the shell layer precursor in deionized water for hydrothermal reaction; centrifugally washing a reaction product to be neutral and performing vacuum drying; and calcining in an H2 / N2 reducing atmosphere to obtain the core-shell structure catalyst taking the manganese-cerium solid solution as the core and CePO4 as the shell.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental catalytic materials, and particularly relates to a core-shell structure manganese-cerium-based bifunctional catalyst, a preparation method thereof, and application of the catalyst in the synergistic catalytic purification of volatile organic compounds (VOCs) and nitrogen oxides (NO x ). BACKGROUND

[0002] Volatile organic compounds (VOCs) and nitrogen oxides (NO x ) are the main pollutants in industrial waste gas, which pose a serious threat to human health and the ecological environment; among them, VOCs can cause respiratory diseases and have a carcinogenic risk, while NO x is the key precursor of photochemical smog, acid rain and ozone layer destruction. Industrial processes account for 40.55% of the total amount of VOCs (steel industry accounts for as high as 26.4%), and ships and agricultural transport vehicles are the main sources of NO x . The current difficulty in pollution control lies in the synergistic catalytic purification of the two types of pollutants, because the molecular sizes of VOCs and NO x are significantly different (the molecular size of VOCs is usually larger than that of NO x ), and traditional single catalysts cannot provide suitable active sites at the same time: VOCs activation needs to rely on Brønsted acid sites to catalyze chain breaking, while NO x adsorption reduction needs Lewis acid sites to combine with adsorbed oxygen to complete oxidative denitration. In the prior art, the two types of pollutants easily compete for adsorption on the surface of a single catalyst, resulting in poor coupling of the reaction path, which is specifically manifested as follows: 1) large molecules of VOCs block the pores and hinder the diffusion of NO x to the active sites; 2) reducing VOCs and NO x3) the reaction intermediates interact to generate N2O and other byproducts, increasing the cost of subsequent processing. In addition, the synergistic mechanism of lattice oxygen and adsorbed oxygen is not clear, resulting in insufficient mineralization rate of VOCs (usually less than 85%). At the level of catalyst design, the existing technology has three limitations: first, there is a lack of molecular size-based screening mechanism, which cannot achieve directional transport and staged catalysis of pollutants through pore zoning; second, the spatial separation of Bronsted acid and Lewis acid sites is insufficient, and the synergistic effect of acid sites is weakened; third, the heterogeneous interface electron transfer effect is not fully utilized, limiting the efficiency of redox cycles. For example, the core-shell carrier disclosed in Chinese invention CN 119236925 A improves the stability of the loading layer by controlling the surface roughness, but does not involve the design of a double-pollutant synergistic catalytic mechanism, and cannot solve the problem of competitive adsorption; the multi-layer core-shell nickel-based catalyst developed in Chinese invention CN 117884131 A optimizes the anti-coking performance and electronic synergistic effect, but its application scenario is single reaction (such as methane reforming), and it does not construct a double-pollutant synergistic catalytic mechanism for VOCs / NO x Zoned catalytic path based on molecular size difference. Selective catalytic reduction (SCR) technology is widely used for denitrification, but in the presence of VOCs, it is easy to cause catalyst poisoning due to competitive adsorption, and the NH3-SCR process can exacerbate the generation of N2O byproducts (concentration can reach more than 50 ppm). In summary, the development of a double-functional catalyst with pore screening function, double-acid site synergy, and heterogeneous interface enhancement is the key breakthrough direction to achieve efficient and synergistic purification of VOCs and NO x High-efficiency synergistic purification; in particular, it needs to solve the problem of limited redox capacity caused by insufficient interface electron transfer efficiency of cerium oxide (CeO2) and cerium phosphate (CePO4) in manganese-cerium-based catalysts. SUMMARY

[0003] The technical problem solved by the present application is to provide a core-shell layered manganese-cerium-based double-functional catalyst, its preparation method and application, which solves the problems of competitive adsorption, multiple byproducts, and poor coupling of catalytic paths in the prior art. The pore screening mechanism is established in the core-shell structure to solve the problem of competitive adsorption caused by the lack of molecular screening mechanism, and the CeO2 / CePO4 heterogeneous interface electron enhancement effect is used to solve the problem of limited redox capacity caused by low electron transfer efficiency, insufficient mineralization rate of VOCs, etc.

[0004] Technical Solution: A method for preparing a core-shell layered manganese-cerium-based bifunctional catalyst, comprising the following steps: (1) dissolving manganese nitrate and cerium nitrate in deionized water at a molar ratio of (2-4):1, adding a template agent and stirring to form a homogeneous solution; (2) adjusting the pH to alkaline by adding ammonia dropwise to generate a coprecipitate of manganese-cerium hydroxide; (3) allowing the catalyst to stand for aging, then centrifuging, washing, and drying to obtain a precursor powder; (4) calcining the precursor powder in an air atmosphere to obtain a manganese-cerium solid solution; (5) dispersing the manganese-cerium solid solution in ethanol, adding cerium nitrate and diammonium hydrogen phosphate, wherein the diammonium hydrogen phosphate provides PO4 3- Ce provided by cerium nitrate 3+ The molar ratio is (1.5-3):1. After adjusting the pH, the CePO4 precursor sol is formed by stirring in a water bath. (6) The sol is dried to obtain the shell precursor. (7) The shell precursor is dispersed in deionized water for hydrothermal reaction. (8) The reaction product is centrifuged and washed until neutral and then dried under vacuum. (9) The product is calcined under a H2 / N2 reducing atmosphere to obtain a core-shell catalyst with manganese cerium solid solution as the core and CePO4 as the shell.

[0005] The molar ratio of manganese nitrate to cerium nitrate in step (1) is 2:1.

[0006] The drying conditions for step (3) are: temperature 60-80℃, time 12-16 hours; the calcination conditions for step (4) are: temperature 500-700℃, time 3-4 hours.

[0007] The PO4 provided by diammonium hydrogen phosphate in step (5) 3- Ce provided by cerium nitrate 3+ The molar ratio is 1.5:1; the water bath conditions for step (5) are: temperature 60-80℃, time 4-5 hours; the drying conditions for step (6) are: temperature 80-100℃, time 12-16 hours.

[0008] The hydrothermal reaction conditions for step (7) are: temperature 160-180℃, time 12-16 hours.

[0009] The vacuum drying conditions for step (8) are: temperature 60-80℃, time 6-8 hours.

[0010] The calcination conditions for step (9) are: temperature 400-500℃, time 2-3 hours.

[0011] The template agent in step (1) is the cationic surfactant CTAB or the block copolymer F127.

[0012] The core-shell layered manganese-cerium-based bifunctional catalyst prepared by the above method has a core layer of manganese-cerium solid solution and a shell layer of cerium phosphate (CePO4), and a CeO2 / CePO4 heterogeneous interface is formed between the core and the shell.

[0013] The above-mentioned core-shell layered manganese-cerium-based bifunctional catalysts in the reaction of VOCs and NO x Applications in collaborative processing.

[0014] Beneficial effects: The core-shell layered manganese-cerium-based bifunctional catalyst prepared by the present invention has the following beneficial effects: (1) It selectively adsorbs VOCs through the outer shell mesoporous layer and catalyzes their chain scission into small molecules through Brønsted acid sites, while the core adsorbs NO through Lewis acid sites. x (1) Small molecules are avoided from competitive adsorption leading to activity inhibition; (2) The CeO2 / CePO4 heterogeneous interface between the core and shell enhances electron transfer ability and improves redox synergistic efficiency; (3) Cerium phosphate in the outer shell selectively adsorbs and catalyzes VOCs chain scission mineralization through Brønsted acid sites. Through oxygen activation and bond breaking, the transfer of oxygen on phosphate controls chain scission and inhibits the generation of by-products such as dioxins; (4) The manganese cerium solid solution in the core adsorbs NO through Lewis acid sites. x It achieves deep oxidation through synergistic adsorption of oxygen and lattice oxygen. Attached Figure Description

[0015] Figure 1 Conversion rate of chlorobenzene (VOCs) in simulated waste gas under different catalysts.

[0016] Figure 2 NO in simulated exhaust gas under different catalysts x Conversion rate. Detailed Implementation

[0017] Example 1 The preparation steps of a core-shell layered manganese-cerium-based bifunctional catalyst are as follows: (1) Prepare the precursor solution by weighing manganese nitrate and cerium nitrate and dissolving them in 100 mL of deionized water at a molar ratio of 2:1. Stir until completely dissolved, add 2 g of CTAB as a template agent, and stir to form a homogeneous solution. (2) Add ammonia water to adjust the pH to 9, and stir continuously to generate manganese cerium hydroxide coprecipitate; (3) Let stand for 12 hours to allow the particles to grow uniformly, collect the precipitate by centrifugation, wash with deionized water and ethanol, and dry in an 80℃ oven for 12 hours to obtain precursor powder. (4) The dried precursor powder was placed in a tube furnace and calcined at 600°C for 3 hours with air to obtain manganese cerium solid solution. (5) Disperse 1g of core material in 50mL of ethanol, add cerium nitrate and diammonium hydrogen phosphate, and PO4 3-With Ce 3+ Mn / Ce molar ratio of 1.5:1, stirring to dissolve, adding ammonia water to adjust pH to 7, stirring in water bath at 60°C for 5 hours, forming CePO4 precursor sol; (6) The sol was placed in an oven at 80°C for 5 hours to dry, obtaining a shell precursor; (7) The precursor was dispersed in 50 mL of deionized water and transferred to a reaction kettle for hydrothermal reaction at 180°C for 12 hours; (8) The reaction product was centrifuged and washed to neutral, and then placed in a vacuum oven at 60°C for vacuum drying for 8 hours; (9) The product was placed in a H2 / N2 atmosphere tube furnace and calcined at 400°C for 2 hours to promote the formation of a heterogeneous structure, and finally a core-shell structure catalyst with a core of Mn-Ce solid solution and a shell of CePO4 was obtained.

[0018] The prepared catalyst was applied to a fixed bed reactor to treat simulated waste gas containing VOCs (taking chlorobenzene as an example) and NO x , with a space velocity of 20,000 h -1 and a temperature of 200-350°C.

[0019] Example 2 The preparation steps of a core-shell layered manganese-cerium-based bifunctional catalyst are as follows: (1) Prepare a precursor solution. Mn(NO3)2 and Ce(NO3)3 were weighed and dissolved in 100 mL of deionized water according to a molar ratio of 2:1, and stirred until completely dissolved. 2 g of CTAB was added as a template agent, and the mixture was stirred to form a homogeneous solution; (2) Ammonia water was added dropwise to adjust the pH to 9, and stirring was continued to form manganese-cerium hydroxide coprecipitate; (3) The mixture was allowed to stand for 12 hours for uniform growth of the particles. The precipitate was collected by centrifugation, washed with deionized water and ethanol, and then placed in an oven at 80°C for drying for 12 hours, obtaining a precursor powder; (4) The dried precursor powder was placed in a tube furnace and calcined at 500°C for 4 hours with air flowing through, obtaining a manganese-cerium solid solution; (5) 1 g of the core layer material was dispersed in 50 mL of ethanol, and Ce(NO3)3 and (NH4)2HPO4 were added according to a molar ratio of 1.5:1, and the mixture was stirred until completely dissolved; 3- With Ce 3+ Mn / Ce molar ratio of 1.5:1, stirring to dissolve, adding ammonia water to adjust pH to 7, stirring in water bath at 60°C for 5 hours, forming CePO4 precursor sol; (6) The sol was placed in an oven at 80°C for 5 hours to dry, obtaining a shell precursor; (7) The precursor was dispersed in 50 mL of deionized water and transferred to a reaction kettle for hydrothermal reaction at 160°C for 16 hours; (8) The reaction product was centrifuged and washed to neutral, and then placed in a vacuum oven at 60°C for vacuum drying for 8 hours; (9) The product was placed in a tube furnace under H2 / N2 atmosphere and calcined at 400°C for 3 hours to promote the formation of heterostructure, and finally a core-shell structure catalyst with Mn-Ce solid solution as the core and CePO4 as the shell was obtained.

[0020] The prepared catalyst was applied to a fixed-bed reactor to treat VOCs (taking chlorobenzene as an example) and NO. x Simulated exhaust gas, space velocity 20,000 h⁻¹ -1 Temperature 200-350℃.

[0021] Example 3 The preparation steps of a core-shell layered manganese-cerium-based bifunctional catalyst are as follows: (1) Prepare the precursor solution by weighing manganese nitrate and cerium nitrate and dissolving them in 100 mL of deionized water at a molar ratio of 2:1. Stir until completely dissolved, add 2 g of F127 as a template agent, and stir to form a homogeneous solution. (2) Add ammonia water to adjust the pH to 9, and stir continuously to generate manganese cerium hydroxide coprecipitate; (3) Let stand for 12 hours to allow the particles to grow uniformly, collect the precipitate by centrifugation, wash with deionized water and ethanol, and dry in an 80℃ oven for 12 hours to obtain precursor powder. (4) The dried precursor powder was placed in a tube furnace and calcined at 500°C for 4 hours to obtain manganese cerium solid solution. (5) Disperse 1g of core material in 50mL of ethanol, add cerium nitrate and diammonium hydrogen phosphate, and PO4 3- With Ce 3+ The molar ratio is 1.5:1. Stir until dissolved, add ammonia dropwise to adjust the pH to 7, stir in a 60℃ water bath for 5 hours to form CePO4 precursor sol; (6) The sol was dried in an oven at 80°C for 5 hours to obtain the shell precursor; (7) Disperse the precursor in 50 mL of deionized water, transfer it to a reaction vessel, and hydrothermally react at 160 °C for 16 hours. (8) Centrifuge and wash the reaction product until it is neutral, and then place it in a vacuum oven at 60°C to dry it for 8 hours. (9) The product was placed in a tube furnace under H2 / N2 atmosphere and calcined at 400°C for 3 hours to promote the formation of heterostructure, and finally a core-shell structure catalyst with Mn-Ce solid solution as the core and CePO4 as the shell was obtained.

[0022] The prepared catalyst was applied to a fixed-bed reactor to treat VOCs (taking chlorobenzene as an example) and NO. x Simulated exhaust gas, space velocity 20,000 h⁻¹ -1 Temperature 200-350℃.

[0023] Comparative Example 1 The preparation steps of the core-shell layered Mn-Ce-based bifunctional catalyst are as follows: (1) Preparation of precursor solution: Mn(NO3)2 and Ce(NO3)3 were weighed and dissolved in 100 mL of deionized water at a molar ratio of 1:1, and stirred until completely dissolved. 2 g of CTAB was added as a template agent, and the mixture was stirred to form a homogeneous solution; (2) Ammonia was added dropwise to adjust the pH to 9, and stirring was continued. Mn-Ce hydroxide coprecipitate was formed; (3) The mixture was allowed to stand for 12 hours for uniform growth of the particles. The precipitate was collected by centrifugation, washed with deionized water and ethanol, and then dried in an 80°C oven for 12 hours to obtain a precursor powder; (4) The dried precursor powder was placed in a tube furnace and calcined at 500°C for 4 hours with air flowing through. A Mn-Ce solid solution was obtained; (5) 1 g of the core layer material was dispersed in 50 mL of ethanol, and Ce(NO3)3 and (NH4)2HPO4 were added. The molar ratio of Ce to PO4 was 1.5:1. The mixture was stirred until dissolved, ammonia was added dropwise to adjust the pH to 7, and stirring was continued in a 60°C water bath for 5 hours to form a CePO4 precursor sol; 3- and Ce 3+ The molar ratio of Ce to PO4 was 1.5:1. The mixture was stirred until dissolved, ammonia was added dropwise to adjust the pH to 7, and stirring was continued in a 60°C water bath for 5 hours to form a CePO4 precursor sol; (6) The sol was dried in an 80°C oven for 5 hours to obtain a shell layer precursor; (7) The precursor was dispersed in 50 mL of deionized water and transferred to a reaction kettle. Hydrothermal reaction was carried out at 160°C for 16 hours; (8) The reaction product was washed by centrifugation until neutral, and then vacuum dried in a 60°C vacuum oven for 8 hours; (9) The product was placed in a H2 / N2 atmosphere tube furnace and calcined at 400°C for 3 hours to promote the formation of a heterogeneous structure. Finally, a core-shell structure catalyst with a core of Mn-Ce solid solution and a shell of CePO4 was obtained.

[0024] The prepared catalyst was applied to a fixed bed reactor to treat simulated waste gas containing VOCs (using chlorobenzene as an example) and NO x at a space velocity of 20,000 h -1 and a temperature of 200-350°C.

[0025] Comparative Example 2 The preparation steps of the core-shell layered Mn-Ce-based bifunctional catalyst are as follows: (1) Preparation of precursor solution: Mn(NO3)2 and Ce(NO3)3 were weighed and dissolved in 100 mL of deionized water at a molar ratio of 2:1, and stirred to form a homogeneous solution; (2) Ammonia was added dropwise to adjust the pH to 9, and stirring was continued. Mn-Ce hydroxide coprecipitate was formed; (3) Let stand for 12 hours to make the particles grow uniformly, collect the precipitate by centrifugation, and dry in an oven at 80°C for 12 hours after washing with deionized water and ethanol to obtain a precursor powder; (4) Place the dried precursor powder in a tube furnace, pass in air at 500°C for calcination for 4 hours to obtain a manganese-cerium solid solution; (5) Disperse 1 g of the core layer material in 50 mL of ethanol, add cerium nitrate and diammonium hydrogen phosphate, PO4 3- , and stir until dissolved. Add ammonia water dropwise to adjust the pH to 7, and stir in a water bath at 60°C for 5 hours to form a CePO4 precursor sol; 3+ (6) Dry the sol in an oven at 80°C for 5 hours to obtain a shell layer precursor; (7) Disperse the precursor in 50 mL of deionized water, and transfer to a reaction kettle for hydrothermal reaction at 160°C for 16 hours; (8) Centrifuge and wash the reaction product until neutral, and then vacuum dry in a vacuum oven at 60°C for 8 hours; (9) Place the product in a H2 / N2 atmosphere tube furnace for calcination at 400°C for 3 hours to promote the formation of a heterogeneous structure, and finally obtain a core-shell structure catalyst with a core of Mn-Ce solid solution and a shell of CePO4.

[0026] The prepared catalyst is applied to a fixed bed reactor to treat simulated waste gas containing VOCs (taking chlorobenzene as an example) and NO x , with a space velocity of 20,000 h -1 and a temperature of 200-350°C.

[0027] Comparative Example 3 A preparation procedure of a core-shell layered manganese-cerium-based bifunctional catalyst is as follows: (1) Prepare a precursor solution. Weigh manganese nitrate and cerium nitrate according to a molar ratio of 2:1, and dissolve in 100 mL of deionized water. Stir until completely dissolved, and add 2 g of CTAB as a template agent. Stir to form a homogeneous solution; (2) Add ammonia water dropwise to adjust the pH to 9, and continue stirring to generate manganese-cerium hydroxide coprecipitate; (3) Let stand for 12 hours to make the particles grow uniformly, collect the precipitate by centrifugation, and dry in an oven at 80°C for 12 hours after washing with deionized water and ethanol to obtain a precursor powder; (4) Place the dried precursor powder in a tube furnace, pass in air at 600°C for calcination for 3 hours to obtain a manganese-cerium solid solution; (5) Disperse 1 g of the core layer material in 50 mL of ethanol, add potassium permanganate and citric acid, and stir until dissolved. Add ammonia water dropwise to adjust the pH to 7, and stir in a water bath at 60°C for 5 hours to form a MnO2 sol; ​(6) The sol was dried in an oven at 80°C for 5 hours to obtain the shell precursor; (7) Disperse the precursor in 50 mL of deionized water, transfer it to a reaction vessel, and hydrothermally react at 180 °C for 12 hours. (8) Centrifuge and wash the reaction product until it is neutral, and then place it in a vacuum oven at 60°C to dry it for 8 hours. (9) The product was placed in a tube furnace under H2 / N2 atmosphere and calcined at 400°C for 2 hours to promote the formation of heterostructure, and finally a core-shell structure catalyst with Mn-Ce solid solution as the core and CePO4 as the shell was obtained.

[0028] The prepared catalyst was applied to a fixed-bed reactor to treat VOCs (taking chlorobenzene as an example) and NO. x The simulated exhaust gas contained 70% VOCs and 70% NO. x Concentration of 30%, space velocity of 20,000 h⁻¹ -1 Temperature 200-350℃.

[0029] The conversion rates of VOCs (chlorobenzene) in simulated waste gas under different catalysts are as follows: Figure 1 As shown. NO in simulated exhaust gas under different catalysts. x Conversion rate, etc. Figure 2 As shown. Figure 1 The data in the figure represent the VOCs (chlorobenzene) conversion rates of simulated waste gas in Examples 1-3 and Comparative Examples 1-3 at a reaction temperature of 350℃. Figure 2 The data in the middle are the simulated waste gas NO in Examples 1-3 and Comparative Examples 1-3 at a reaction temperature of 350℃. x Conversion rate. In the three examples, the core-shell layered manganese-cerium-based bifunctional catalyst prepared in Example 1 was used to simulate the conversion of VOCs (chlorobenzene) and NO in the exhaust gas. x The removal rates were the highest, at 98.5% and 96.2%, respectively; among the three comparative examples, the manganese-cerium-based core-shell catalyst prepared in Comparative Example 1 showed the highest removal rates of VOCs (chlorobenzene) and NO in the simulated waste gas. x The removal rates were the highest, at 87.6% and 91.5%, respectively. Overall, the composite of multiple metals in the core-shell structure better promoted the removal of pollutants and improved the stability of the catalyst.

[0030] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for preparing a core-shell layered manganese-cerium-based bifunctional catalyst, characterized in that, Includes the following steps: (1) Dissolve manganese nitrate and cerium nitrate in deionized water at a molar ratio of (2-4):1, add template agent and stir to form a homogeneous solution; (2) Add ammonia water to adjust the pH to alkaline to generate a coprecipitate of manganese cerium hydroxide; (3) After standing and aging, centrifuge, wash, and dry to obtain precursor powder; (4) Calcine the precursor powder in air atmosphere to obtain manganese cerium solid solution; (5) Disperse the manganese cerium solid solution in ethanol, add cerium nitrate and diammonium hydrogen phosphate, wherein the diammonium hydrogen phosphate provides PO4 3- Ce provided by cerium nitrate 3+ The molar ratio is (1.5-3):

1. After adjusting the pH, the CePO4 precursor sol is formed by stirring in a water bath. (6) The sol is dried to obtain the shell precursor. (7) The shell precursor is dispersed in deionized water for hydrothermal reaction. (8) The reaction product is centrifuged and washed until neutral and then dried under vacuum. (9) The product is calcined under a H2 / N2 reducing atmosphere to obtain a core-shell catalyst with manganese cerium solid solution as the core and CePO4 as the shell.

2. The method according to claim 1, characterized in that, The molar ratio of manganese nitrate to cerium nitrate in step (1) is 2:

1.

3. The method according to claim 1, characterized in that, The drying conditions for step (3) are: temperature 60-80℃, time 12-16 hours; the calcination conditions for step (4) are: temperature 500-700℃, time 3-4 hours.

4. The method according to claim 1, characterized in that, The PO4 provided by diammonium hydrogen phosphate in step (5) 3- Ce provided by cerium nitrate 3+ The molar ratio is 1.5:1; the water bath conditions for step (5) are: temperature 60-80℃, time 4-5 hours; the drying conditions for step (6) are: temperature 80-100℃, time 12-16 hours.

5. The method according to claim 1, characterized in that, The hydrothermal reaction conditions for step (7) are: temperature 160-180℃, time 12-16 hours.

6. The method according to claim 1, characterized in that, The vacuum drying conditions for step (8) are: temperature 60-80℃, time 6-8 hours.

7. The method according to claim 1, characterized in that, The calcination conditions for step (9) are: temperature 400-500℃, time 2-3 hours.

8. The method according to claim 1, characterized in that, The template agent in step (1) is the cationic surfactant CTAB or the block copolymer F127.

9. The core-shell layered manganese-cerium-based bifunctional catalyst prepared by the method according to any one of claims 1-8, wherein the core layer is a manganese-cerium solid solution, the shell layer is cerium phosphate, and a CeO2 / CePO4 heterogeneous interface is formed between the core and the shell.

10. The core-shell layered manganese-cerium-based bifunctional catalyst of claim 9 in the reaction of VOCs and NO x Applications in collaborative processing.

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