Composite catalyst for nitrous oxide decomposition and preparation method thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a composite catalyst for nitrous oxide decomposition and a preparation method thereof.The composite catalyst is of a three-dimensional flower-shaped structure and comprises a composite carrier and active metal loaded on the composite carrier; the composite carrier is composed of a modification additive and a carrier oxide; the performance additive is composed of alkali metal oxide and rare earth metal oxide; the carrier oxide is selected from one of aluminum oxide, titanium dioxide and silicon dioxide; the active metal comprises cobalt oxide and vanadium oxide. The multi-metal catalyst has the advantages that the multi-metal catalyst with a three-dimensional flower-shaped structure is formed by loading cobalt and vanadium active metals on aluminum oxide and under the synergistic effect of alkali metal and rare earth metal, so that the stability and durability of the catalyst in a high-temperature environment are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a composite catalyst for decomposition of nitrous oxide and a preparation method thereof. BACKGROUND

[0002] Nitrous oxide (N2O) is a key greenhouse gas, with a global warming effect (GWE) 310 times that of carbon dioxide and 21 times that of methane. In addition, N2O not only destroys the ozone layer, but also causes global climate change, with a residence time in the atmosphere of up to 150 years. In industrial production, especially in the production of nitric acid and adipic acid, a large amount of N2O is released, accounting for 97% of total industrial emissions. Therefore, how to effectively regulate and eliminate N2O has become an important issue in global environmental protection.

[0003] Currently, the elimination methods of N2O mainly include thermal decomposition and catalytic decomposition. Thermal decomposition requires high temperature conditions of 1200-1500℃, consumes a large amount of energy, and produces greenhouse gases such as CO2. The catalytic decomposition method has the advantages of simple process, no secondary pollution, and low investment cost, and is an economical and efficient method. However, the existing catalysts are easily deactivated at high temperature, especially in the temperature range of 800-1000℃, which affects the process efficiency and environmental benefits.

[0004] The gas produced in the production of nitric acid usually contains 500-2000ppm of N2O, 200-3000ppm of NOx, 1-5% of O2, and other components.

[0005] Patent CN102658195A describes a Fe / ZSM-5 zeolite catalyst for reducing the content of N2O in gas and a preparation method thereof. The catalyst is prepared by loading Fe on ZSM-5 zeolite molecular sieve, and can operate at a lower temperature, mainly suitable for treating gas with low N2O content, especially the gas in nitric acid production workshops. Patent CN101875015A modifies the molecular sieve with iron ions and noble metal ions in order to reduce the activity temperature of the catalyst. Most of the research aims to reduce the activity temperature of the catalyst while ensuring the efficiency of N2O decomposition. The above-mentioned catalysts are mainly suitable for low temperature conditions, and there is still a lack of effective solutions for the rapid decline of catalyst activity under high temperature conditions.

[0006] To solve the above technical problems, researchers have been exploring new and efficient N2O decomposition catalysts. Currently, the research mainly focuses on three types of catalysts: noble metal catalysts, composite metal oxide catalysts, and molecular sieve catalysts. However, these catalysts each have their limitations, such as high cost of noble metal catalysts and complicated preparation process of molecular sieve catalysts, and oxygen in the reaction system will affect the activity of the catalyst. SUMMARY

[0007] The present application aims at overcoming the deficiencies in the prior art, and provides a composite catalyst for decomposition of nitrous oxide and a preparation method thereof, which significantly improves the stability and durability of the catalyst under high temperature environment by loading cobalt and vanadium active metals on alumina and forming a three-dimensional flower-shaped structure of the multi-metal catalyst through synergistic effect of alkali metals and rare earth metals.

[0008] The present application is realized by the following technical solutions: on one hand, a composite catalyst for decomposition of nitrous oxide is provided, which is a three-dimensional flower-shaped structure and comprises a composite carrier and active metals loaded on the composite carrier.

[0009] The composite carrier is composed of a modified auxiliary agent and a carrier oxide;

[0010] The modified auxiliary agent is composed of alkali metal oxides and rare earth metal oxides;

[0011] The carrier oxide is selected from one of alumina, titanium dioxide and silicon dioxide;

[0012] The active metals include cobalt oxides and vanadium oxides.

[0013] Further, the alkali metal oxides are selected from cesium oxides;

[0014] The rare earth metal oxides are selected from one or more of cerium oxides, lanthanum oxides, praseodymium oxides, neodymium oxides, promethium oxides, samarium oxides, europium oxides and gadolinium oxides.

[0015] Further, the molar ratio of the metal elements of the cesium oxides, the rare earth metal oxides and the carrier oxides is 0.005-0.05:0.05-0.5:0.8-1.

[0016] Further, the mass percentage content of the cobalt element is 1-6wt%; and the mass percentage content of the vanadium element is 0.5-5wt%.

[0017] Further, the composite carrier is composed of cesium oxides, cerium oxides and alumina; and specifically as shown in the following formula (I):

[0018] Co-V / Cs x Ce y Al z O m Formula (I);

[0019] The mass percentage of Co in the above formula (I) is 1.5-5 wt%; the mass percentage of V is 0.5-5 wt%; the value of x is 0.005-0.05; the value of y is 0.00.5-0.5; the value of z is 0.8-1, and m is the atomic ratio of oxygen required to satisfy the valence of each element.

[0020] Through the above technical solution, the three-dimensional flower-shaped structure carrier of the application takes alumina as the core, and cesium and cerium are uniformly distributed on the surface of the alumina, the mutual interaction of the three surfaces enhances the stability of the carrier, the composite carrier is calcined by using reducing gas hydrogen, so that the carrier surface structure is formed with defect oxygen vacancy structure, which is beneficial to the adsorption of noble metals. Further, the noble metals cobalt and vanadium are highly dispersed in the form of oxides at the oxygen vacancy position on the surface of the carrier by using the hydrothermal method, the catalyst growth structure is controlled by the ratio of ethylene glycol and aqueous solution, and the cobalt and vanadium are tightly fixed at the oxygen vacancy position of the composite carrier by calcining in an air atmosphere, which is beneficial to further exerting the coordination and synergistic effect of cesium and cerium additives and active metals, and improving the catalyst activity.

[0021] The composite carrier oxide has p-type semiconductor properties, and the introduction of cesium and cerium in alumina is to make the electrons flow from the metal to the semiconductor and the holes flow from the semiconductor to the metal when the semiconductor contact is formed, to form an electron accumulation layer near the semiconductor region, and because of the existence of the Schottky barrier and the formation of the metal-semiconductor interface built-in electric field, they will prevent the electrons from returning to the metal from the semiconductor, so that the composite carrier obtained can have more oxygen vacancies, which is more conducive to improving the catalyst activity. The active components CoO and V2O5 have reversible redox property, strong oxidizing property and high charge mobility, and their crystal face structure and oxygen vacancy density directly enhance the catalytic activity, which performs excellently in ultra-low temperature denitration and other reactions, and the introduction of the active components into the alumina composite carrier can further promote the exchange of electrons and holes, and the strong interaction between Co / V oxides and Cs / Ce oxides weakens the corresponding metal-oxygen bond, and improves the catalytic reduction property of the active components.

[0022] The catalyst can efficiently decompose N2O in the temperature range of 500-1000℃, especially in the high temperature range of 800-1000℃, effectively solving the problem of easy deactivation of existing catalysts at high temperature, and prolonging the service life of the catalyst. The good high-temperature activity of the catalyst is due to its unique redox property, doped electron structure optimization and interface synergistic effect, which together enhance the reaction kinetics and stability. The transition metal oxides such as CoO have adjustable Co 2+ / Co 3+The redox pair promotes the adsorption and activation of N2O molecules at high temperatures and accelerates the breaking of N-O bonds to generate N2 and O2. This mechanism is derived from the close matching of the electronic donor-acceptor interaction on the catalyst surface with the frontier orbital arrangement of the N2O reactant. The introduction of Cs, Ce, Al and other additives adjusts the work function and oxygen vacancy density of the catalyst, enhances the surface oxygen mobility, and thus improves the high-temperature reaction rate. The composite catalyst CoO-V2O5 realizes efficient decomposition of N2O through interfacial redox behavior, CoO activates O2 and generates N2O intermediates, while the V2O5 interface promotes the dissociation of N-O bonds and inhibits the formation of by-products, maintaining high conversion at high temperatures. The CoO-based catalyst has excellent lattice stability at high temperatures, avoiding sintering and deactivation, ensuring the persistent exposure of active sites, and doping additives further strengthen the lattice structure and improve the high-temperature aging resistance.

[0023] A method for preparing the composite catalyst is also provided, comprising the following steps:

[0024] Step 1) Synthesis of the carrier;

[0025] The aluminum nitrate solution is placed in a 40-80°C water bath, and ammonia water is added dropwise under stirring until the pH reaches 10-11. The mixture is then transferred to a hydrothermal reactor and reacted at 110-160°C for 10-24 hours. After filtration, washing with deionized water, drying at 120-150°C for 10-24 hours, and calcining at 500-700°C for 6-8 hours, an aluminum oxide carrier is obtained.

[0026] Step 2) Preparation of the modified carrier;

[0027] The aluminum oxide carrier obtained in step 1) is crushed to a particle size of ≤50μm, and a mixed solution containing cesium nitrate and cerium nitrate is added. After stirring for 6-8 hours, the mixture is dried at 120-150°C for 10-24 hours and calcined at 500-700°C for 6-8 hours to obtain a Cs-Ce-Al composite carrier.

[0028] Step 3) Reduction treatment;

[0029] The carrier obtained in step 2) is reduced and calcined at 200-500°C for 2-6 hours in a reducing atmosphere.

[0030] Step 4) Active metal loading;

[0031] To the carrier treated in step 3), a cobalt nitrate solution and an ammonium metavanadate solution are added, followed by a mixed solvent of ethylene glycol and water in a volume ratio of 1-5:1. The mixture is stirred to form a slurry, dried at 120-150°C for 10-24 hours, and calcined at 500-700°C in static air for 6-8 hours to obtain the catalyst.

[0032] Further, in step 1), the ammonia water is added at a rate of 2-6mL / min.

[0033] Furthermore, in step 3), the reducing atmosphere is selected from H2, CO, or an inert gas containing H2.

[0034] Further, in step 4), the mass ratio of the mixed solvent of ethylene glycol and water to the carrier is 10 to 30:1.

[0035] Further, in step 4), the catalyst has a specific surface area ≥ 100 m². 2 / g.

[0036] Through the above technical solution, the three-dimensional flower-like Cs / Ce-Al composite oxide supported diatomic CO-V catalyst of the present invention exhibits high dispersibility and specific surface area, improving catalyst activity and treatment efficiency, and meeting the growing demands of industrial applications. This catalyst demonstrates excellent performance under high temperature and high pressure conditions, achieving a nitrous oxide decomposition rate of over 95%, significantly improving N2O removal efficiency.

[0037] This invention uses a three-dimensional flower-like Cs / Ce-Al composite oxide as a support and controls the formation of a three-dimensional flower-like structure of the catalyst using a hydrothermal method. This not only increases the specific surface area, dispersion, uniformity and high-temperature stability of the support, but also enhances the electron transfer between metals. This method is simple, has low production cost, and is conducive to industrial production.

[0038] Beneficial effects

[0039] This invention significantly improves the stability and durability of a multi-metal catalyst with a three-dimensional flower-like structure by loading cobalt and vanadium active metals onto alumina and using cesium and cerium as dual promoters.

[0040] The three-dimensional flower-like Cs / Ce-Al composite oxide-supported diatomic CO-V catalyst of this invention exhibits high dispersibility and specific surface area, improving catalyst activity and treatment efficiency, thus meeting the growing demands of industrial applications. This catalyst demonstrates excellent performance under high temperature and high pressure conditions, achieving a nitrous oxide decomposition rate of over 95%, significantly enhancing N2O removal efficiency.

[0041] The catalyst of this invention exhibits excellent anti-aging properties and maintains stable catalytic activity at high temperatures, effectively extending its service life and reducing replacement and maintenance costs. The active metal is in close contact with the support, and through the interaction between the metal and the composite support, electron transfer occurs between Co and the support promoter Cs. This strong interaction allows Co to exist in a +2 oxidation state during the reaction, which is more beneficial for the adsorption and activation of reactants.

[0042] The catalyst of the present application is also suitable for removal of N2O in tail gas of nitric acid or adipic acid device and other processes, has strong practicability and market application value, can effectively reduce N2O emission, and makes positive contribution to environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a scanning electron microscope image of the catalyst of Example 1.

[0044] Figure 2 It is a scanning electron microscope image of the catalyst of Example 1.

[0045] Figure 3 It is a scanning electron microscope image of the catalyst of Example 4.

[0046] Figure 4 It is a scanning electron microscope image of the catalyst of Example 6.

[0047] Figure 5 It is a scanning electron microscope image of the catalyst of Example 6. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with specific examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0049] All other examples obtained by those skilled in the art based on the examples in the present application without making creative efforts are within the protection scope of the present application. The experimental methods in the following examples without specific conditions are usually according to conventional conditions or according to the conditions suggested by manufacturers. All percentages, ratios, proportions or parts are by weight unless otherwise specified.

[0050] The reagents and raw materials used in the examples and comparative examples of the present application can be obtained through commercial channels unless otherwise specified.

[0051] Example 1: 1.5%Co-0.5%V / Cs 0.005 Ce 0.05 Al 0.8 O 1.3 Preparation of catalyst

[0052] Step one, take the 80 ml, 1 mol / L aluminum nitrate solution has been configured into a flask, in 60 ℃ water bath stirring dropwise add ammonia to adjust the pH to 10, continue to stir 30 min after the mixture was transferred to hydrothermal reactor, 125 ℃ conditions for 16 h. The hydrothermal reaction slurry was filtered, washed, 120 ℃ oven drying 12 h, the dried solid into the muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcined 6 h. The resulting solid grinding to powder, add 5 ml, 0.1 mol / L cesium nitrate solution and 5 ml, 1 mol / L cerium nitrate solution, stirring 8 hours, prepared slurry, dried in 120 ℃ oven for 12 hours, then placed in the muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcined 6 hours. Again the solid grinding to powder placed in the tube furnace H2(1.5% hydrogen, helium balance gas) atmosphere 500 ℃ (heating rate 2 ℃ / min) calcined 2 h, prepared by hydrogen treatment of cesium cerium composite oxide carrier.

[0053] Step two, take 5 g of the cesium cerium composite oxide carrier obtained in step one, grinding to powder, add the 1.27 ml, 1 mol / L cobalt nitrate solution and 0.5 ml, 1 mol / L ammonium metavanadate solution has been configured, then add 10 ml of ethylene glycol and 50 ml of deionized water, stirring 8 hours, prepared slurry, the slurry was dried in 120 ℃ oven for 12 h, the dried solid placed in the muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcined 6 h, prepared three-dimensional flower-like structure of cesium cerium aluminum composite oxide supported bimetallic CO-V catalyst.

[0054] Example 2: 1.5% Co-0.5% V / Cs 0.05 Ce 0.5 Al1O 2.53 Preparation of catalyst

[0055] Step 1: Take the prepared 100 ml, 1 mol / L aluminum nitrate solution into a flask, and add ammonia water to adjust the pH to 10 while stirring in a 60°C water bath. Continue stirring for 30 min, then transfer the mixture to a hydrothermal reactor, and react at 130°C for 18 h. Filter the hydrothermal reaction slurry, wash, and dry in a 130°C oven for 14 h. Put the dried solid into a muffle furnace at 550°C (heating rate 2°C / min) and calcine for 7 h. Grind the obtained solid into powder, add 50 ml, 0.1 mol / L cesium nitrate solution and 50 ml, 1 mol / L cerium nitrate solution, and stir for 7 h to prepare a slurry. Dry in a 130°C oven for 14 h, then calcine in a muffle furnace at 550°C (heating rate 2°C / min) for 7 h. Grind the solid again and place it in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 400°C (heating rate 2°C / min) for 3 h to prepare the hydrogen-treated cesium-cerium composite oxide carrier.

[0056] Step 2: Take 5 g of the cesium-cerium composite oxide carrier obtained in Step 1, grind into powder, add 1.27 ml, 1 mol / L cobalt nitrate solution and 0.5 ml, 1 mol / L ammonium metavanadate solution, and then add 20 ml of ethylene glycol and 40 ml of deionized water. Stir for 7 h to prepare a slurry. Dry the obtained slurry in a 130°C oven for 13 h, and then calcine the dried solid in a muffle furnace at 550°C (heating rate 2°C / min) for 7 h to prepare a three-dimensional flower-shaped structure cesium-cerium-aluminum composite oxide supported bimetallic CO-V catalyst.

[0057] Example 2 improves the content of cesium, cerium and aluminum on the composite carrier compared to Example 1. The hydroxyl groups and other functional groups formed by oxygen atoms on the surface of the carrier can serve as metal anchoring sites, promoting uniform dispersion of metal particles and inhibiting agglomeration, thereby improving catalytic efficiency.

[0058] Example 3: 5% Co-5% V / Cs 0.05 Ce 0.5 Al1O 2.53 Preparation of catalyst

[0059] Step 1, take the 100 ml, 1 mol / L aluminum nitrate solution configured in the flask, in the 60 ℃ water bath, stirring, adding ammonia water to adjust the pH to 10, continue to stir for 30 min, then transfer the mixed solution to the hydrothermal reactor, react at 135 ℃ for 18 h. The hydrothermal reaction slurry was filtered, washed, and dried in an oven at 140 ℃ for 10 h. The dried solid was placed in a muffle furnace at 600 ℃ (heating rate 2 ℃ / min) and calcined for 6 h. The obtained solid was ground into powder, 50 ml, 0.1 mol / L cesium nitrate solution and 50 ml, 1 mol / L cerium nitrate solution were added, stirred for 8 hours, prepared slurry, dried in 140 ℃ oven for 10 hours, then placed in muffle furnace at 600 ℃ (heating rate 2 ℃ / min) calcined for 4 hours. The solid was ground again and placed in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 550 ℃ (heating rate 2 ℃ / min) for 2 h to prepare the hydrogen-treated cesium-cerium composite oxide carrier.

[0060] Step 2, take 5 g of the cesium-cerium composite oxide carrier obtained in step 1, grind into powder, add 4.24 ml of 1 mol / L cobalt nitrate solution and 4.9 ml of 1 mol / L ammonium metavanadate solution, then add 30 ml of ethylene glycol and 30 ml of deionized water, stir for 6 hours, prepare the slurry, dry the obtained slurry in a 140 ℃ oven for 10 h, and then place the dried solid in a muffle furnace at 600 ℃ (heating rate 2 ℃ / min) and calcine for 4 h to prepare a three-dimensional flower-shaped structure cesium-cerium-aluminum composite oxide supported bimetallic CO-V catalyst.

[0061] Example 3 has higher active metal cobalt and vanadium content than Example 2, and the surface lattice oxygen of transition metal oxides CoO and V2O5 increases, which can accelerate the oxygen transfer process in the redox reaction, and is beneficial to the improvement of reaction conversion rate.

[0062] Example 4: 5%Co-3%V / Cs 0.02 Ce 0.5 Al 0.9 O 2.36 Preparation of catalyst

[0063] Step 1, take the 90ml, 1mol / L aluminum nitrate solution configured in the flask, in the 60℃ water bath, add ammonia water to adjust the pH to 10, continue to stir for 30min, then transfer the mixed solution to the hydrothermal reactor, react at 130℃ for 16h. The hydrothermal reaction slurry was filtered, washed, and dried in a 150℃ oven for 12h. The dried solid was placed in a muffle furnace at 500℃ (heating rate 2℃ / min) and calcined for 4h. The obtained solid was ground into powder, 20ml, 0.1mol / L cesium nitrate solution and 50ml, 1mol / L cerium nitrate solution were added, stirred for 6 hours, and a slurry was prepared. The slurry was dried in a 150℃ oven for 12h, and then calcined in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. The solid was ground again and placed in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 400℃ (heating rate 2℃ / min) for 4h to obtain the cesium-cerium composite oxide carrier treated by hydrogen.

[0064] Step 2, take 5g of the cesium-cerium composite oxide carrier obtained in step 1, grind into powder, add 4.24ml of 1mol / L cobalt nitrate solution and 2.95ml of 1mol / L ammonium metavanadate solution, then add 10ml of ethylene glycol and 50ml of deionized water, stir for 6 hours to prepare a slurry. The obtained slurry was dried in a 150℃ oven for 12h, and the dried solid was calcined in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h to obtain a three-dimensional flower-shaped structure cesium-cerium-aluminum composite oxide supported bimetallic CO-V catalyst.

[0065] Example 4: The ratio of active metal cobalt and vanadium to composite carrier cesium and cerium is optimized compared to the above examples. Excessive oxidation of the metal surface will cover the active center, reducing the N2O adsorption capacity. At the same time, high oxygen carriers may promote non-target oxidation of N2O in impurity gas systems, reducing selectivity. Therefore, by further adjusting the catalyst formula, a catalyst with high conversion rate and selectivity is obtained.

[0066] Example 5: 5%Co-3%V / Cs 0.02 Ce 0.3 Al 0.9 O 1.96 Preparation of catalyst

[0067] Step one, take commercially available titanium dioxide powder 7.2g (i.e. Ti content 0.09mol), add 20ml, 0.1mol / L cesium nitrate solution and 50ml, 1mol / L cerium nitrate solution, stir for 6 hours, prepare slurry, dry in 120℃ oven for 16 hours, then put in muffle furnace at 550℃ (heating rate 2℃ / min) for 4 hours. Again grind the solid and put in tube furnace under H2 (1.5% hydrogen, helium balance gas) atmosphere at 400℃ (heating rate 2℃ / min) for 2h, to prepare the hydrogen treated cesium cerium composite oxide carrier.

[0068] Step two, take 5g of the cesium cerium composite oxide carrier obtained in step one, grind to powder, add 4.24ml of prepared 1mol / L cobalt nitrate solution and 2.95ml of prepared 1mol / L ammonium metavanadate solution, then add 10ml of ethylene glycol and 50ml of deionized water, stir for 8 hours, prepare slurry, dry the obtained slurry in a 120℃ oven for 16h, calcine the dried solid in a muffle furnace at 550℃ (heating rate 2℃ / min) for 4h, to prepare the three-dimensional flower-shaped structure cesium cerium aluminum composite oxide supported bimetallic CO-V catalyst.

[0069] Example 5: The carrier is replaced by titanium dioxide in comparison with example 4, the effect of alumina and titanium dioxide carrier in this catalyst is similar, which improves the stability and durability of the catalyst in high temperature environment, and no powdering phenomenon occurs during long time high temperature operation.

[0070] Example 6: 5%Co-3%V / Cs 0.02 La 0.5 Al 0.9 O 2.11 Preparation of catalyst

[0071] Step one, take 90ml of prepared 1mol / L aluminum nitrate solution into a flask, add ammonia water in a 60℃ water bath while stirring to adjust the pH to 10, continue stirring for 30min, then transfer the mixture to a hydrothermal reaction kettle, react at 130℃ for 16h. The hydrothermal reaction slurry is filtered, washed, dried in a 150℃ oven for 12h, and then calcined in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. Grind the obtained solid to powder, add 20ml of 0.1mol / L cesium nitrate solution and 50ml of 1mol / L lanthanum nitrate solution, stir for 6 hours, prepare slurry, dry in a 150℃ oven for 12 hours, then calcine in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4 hours. Again grind the solid and put in tube furnace under H2 (1.5% hydrogen, helium balance gas) atmosphere at 400℃ (heating rate 2℃ / min) for 4h, to prepare the hydrogen treated cesium lanthanum composite oxide carrier.

[0072] Step two, take 5g of the lanthanum cesium composite oxide carrier obtained in step one, grind into powder, add the prepared 4.24ml, 1mol / L cobalt nitrate solution and 2.95ml, 1mol / L ammonium metavanadate solution, then add 10ml of ethylene glycol and 50ml of deionized water, stir for 6 hours, prepare the slurry, dry the obtained slurry in an oven at 150℃ for 12h, and then calcine the dried solid in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h, to obtain a three-dimensional flower-shaped structure of cesium lanthanum aluminum composite oxide supported bimetallic CO-V catalyst.

[0073] In example 6, the rare earth element is replaced by lanthanum, and the prepared catalyst has similar effect on N2O decomposition, indicating that the rare earth elements have similar properties, and Ce, La and other additives can adjust the work function and oxygen vacancy density of the catalyst, and enhance the surface oxygen mobility.

[0074] Example 7: 5%Co-3%V / Cs 0.02 Nd 0.5 Al 0.9 O 2.11 Preparation of catalyst

[0075] Step one, take the prepared 90ml, 1mol / L aluminum nitrate solution and put it into a flask, add ammonia water in a 60℃ water bath while stirring to adjust the pH to 10, continue stirring for 30min, then transfer the mixed solution to a hydrothermal reaction kettle, and react at 130℃ for 16h. The hydrothermal reaction slurry is filtered, washed, dried in an oven at 150℃ for 12h, and then calcined in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. The obtained solid is ground into powder, 20ml of 0.1mol / L cesium nitrate solution and 50ml of 1mol / L neodymium nitrate solution are added, stirred for 6 hours, and then prepared into a slurry. Dry the slurry in an oven at 150℃ for 12h, and then calcine the dried solid in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. The solid is ground again and placed in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 400℃ (heating rate 2℃ / min) for 4h to obtain a hydrogen-treated cesium neodymium composite oxide carrier.

[0076] Step two, take 5g of the lanthanum cesium composite oxide carrier obtained in step one, grind into powder, add the prepared 4.24ml, 1mol / L cobalt nitrate solution and 2.95ml, 1mol / L ammonium metavanadate solution, then add 10ml of ethylene glycol and 50ml of deionized water, stir for 6 hours, prepare the slurry, dry the obtained slurry in an oven at 150℃ for 12h, and then calcine the dried solid in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h, to obtain a three-dimensional flower-shaped structure of cesium lanthanum aluminum composite oxide supported bimetallic CO-V catalyst.

[0077] Example 7: Compared with Example 4, the rare earth element is replaced by neodymium, and the prepared catalyst has similar effect on N2O decomposition, indicating that the rare earth elements have similar properties, and Ce, Nd and other additives can adjust the work function and oxygen vacancy density of the catalyst, and enhance the surface oxygen mobility.

[0078] Example 8: 5% Co-3% V / Cs 0.02 Ce 0.3 Al 0.9 O 1.96 Preparation of catalyst

[0079] Step one: Take the prepared 90ml, 1mol / L aluminum nitrate solution into a flask, add ammonia water to adjust the pH to 10 in a 60℃ water bath, continue stirring for 30min, then transfer the mixture to a hydrothermal reactor, and react at 130℃ for 16h. The hydrothermal reaction slurry is filtered, washed, and dried in a 150℃ oven for 12h. The dried solid is calcined in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. The obtained solid is ground into powder, 20ml, 0.1mol / L cesium nitrate solution and 30ml, 1mol / L cerium nitrate solution are added, and stirred for 6h to prepare a slurry. The slurry is dried in a 150℃ oven for 12h, and then calcined in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. The solid is ground again and placed in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 400℃ (heating rate 2℃ / min) for 4h to prepare the hydrogen-treated cesium-cerium composite oxide carrier.

[0080] Step two: Take 5g of the cesium-cerium composite oxide carrier obtained in step one, grind it into powder, add 4.24ml of 1mol / L cobalt nitrate solution and 2.95ml of 1mol / L ammonium metavanadate solution, and then add 10ml of ethylene glycol and 50ml of deionized water, stir for 6h to prepare a slurry. The obtained slurry is dried in a 150℃ oven for 12h, and then calcined in a muffle furnace at 500℃ (heating rate 2℃ / min) for 4h to prepare a three-dimensional flower-shaped structure cesium-cerium-aluminum composite oxide supported bimetallic CO-V catalyst.

[0081] Example 8: Compared with Example 4, the Cs:Ce:Al molar ratio is adjusted to 0.02:0.3:0.9, and the decrease of Ce content leads to the decrease of oxygen vacancy density, which affects the promotion of the catalyst to the redox reaction.

[0082] Example 9: 5% Co-3% V / Cs 0.02 Ce 0.1 Al 0.9 O 1.56 Preparation of catalyst

[0083] Step one, take the prepared 90ml, 1mol / L aluminum nitrate solution into a flask, in 60℃ water bath, stirring, adding ammonia water to adjust pH to 10, continue stirring for 30min, then transfer the mixture to hydrothermal reactor, react at 130℃ for 16h. The hydrothermal reaction slurry was filtered, washed, dried in 150℃ oven for 12h, then the dried solid was calcined in muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. The obtained solid was ground into powder, 20ml, 0.1mol / L cesium nitrate solution and 10ml, 1mol / L cerium nitrate solution were added, stirred for 6h, prepared slurry, dried in 150℃ oven for 12h, then calcined in muffle furnace at 500℃ (heating rate 2℃ / min) for 4h. The solid was ground again and placed in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 400℃ (heating rate 2℃ / min) for 4h to prepare the hydrogen treated cesium-cerium composite oxide carrier.

[0084] Step two, take 5g of the cesium-cerium composite oxide carrier obtained in step one, grind into powder, add prepared 4.24ml, 1mol / L cobalt nitrate solution and 2.95ml, 1mol / L ammonium metavanadate solution, then add 10ml ethylene glycol and 50ml deionized water, stir for 6h, prepare slurry, dry the obtained slurry in 150℃ oven for 12h, then calcine the dried solid in muffle furnace at 500℃ (heating rate 2℃ / min) for 4h to prepare three-dimensional flower-like structure cesium-cerium-aluminum composite oxide supported bimetallic CO-V catalyst.

[0085] Example 9: adjust the Cs:Ce:Al molar ratio to 0.02:0.1:0.9, reduce the Ce content, which leads to the decrease of oxygen vacancy density, affecting the promotion of the catalyst to the redox reaction.

[0086] Comparative example 1: 5% Co / Cs 0.02 Ce 0.5 Al 0.9 O 2.36 Preparation of catalyst

[0087] Step one, take the 90 ml, 1 mol / L aluminum nitrate solution which has been configured into a flask, in 60 ℃ water bath, stirring while adding ammonia to adjust pH to 10, continue to stir for 30 min, then transfer the mixed solution to hydrothermal reactor, 130 ℃ for 16 h. The hydrothermal reaction slurry was filtered, washed, dried in 150 ℃ oven for 12 h, the dried solid was placed in a muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcination for 4 h. The resulting solid was ground to powder, add 20 ml, 0.1 mol / L cesium nitrate solution and 50 ml, 1 mol / L cerium nitrate solution, stirring for 6 hours, prepared slurry, dried in 150 ℃ oven for 12 hours, then placed in a muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcination for 4 hours. Again the solid was ground and placed in a tube furnace H2(1.5% hydrogen, helium balance gas) atmosphere 400 ℃ (heating rate 2 ℃ / min) calcination for 4 h, prepared after hydrogen treatment of cesium cerium composite oxide carrier.

[0088] Step two, take 5 g of the cesium cerium composite oxide carrier obtained in step one, grind to powder, add the 4.24 ml, 1 mol / L cobalt nitrate solution which has been configured, then add 10 ml of ethylene glycol and 50 ml of deionized water, stir for 6 hours, prepared slurry, the slurry was dried in 150 ℃ oven for 12 h, the dried solid was placed in a muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcination for 4 h, prepared three-dimensional flower-like structure cesium cerium aluminum composite oxide supported bimetallic CO-V catalyst.

[0089] Comparative example 2: 3% V / Cs 0.02 Ce 0.5 Al 0.9 O 2.36 Preparation of catalyst

[0090] Step one, take the 90 ml, 1 mol / L aluminum nitrate solution which has been configured into a flask, in 60 ℃ water bath, stirring while adding ammonia to adjust pH to 10, continue to stir for 30 min, then transfer the mixed solution to hydrothermal reactor, 130 ℃ for 16 h. The hydrothermal reaction slurry was filtered, washed, dried in 150 ℃ oven for 12 h, the dried solid was placed in a muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcination for 4 h. The resulting solid was ground to powder, add 20 ml, 0.1 mol / L cesium nitrate solution and 50 ml, 1 mol / L cerium nitrate solution, stirring for 6 hours, prepared slurry, dried in 150 ℃ oven for 12 hours, then placed in a muffle furnace 500 ℃ (heating rate 2 ℃ / min) calcination for 4 hours. Again the solid was ground and placed in a tube furnace H2(1.5% hydrogen, helium balance gas) atmosphere 400 ℃ (heating rate 2 ℃ / min) calcination for 4 h, prepared after hydrogen treatment of cesium cerium composite oxide carrier.

[0091] Step two, take 5 g of the cesium cerium composite oxide carrier obtained in step one, grind to powder, add the prepared 2.95 ml of 1 mol / L ammonium metavanadate solution, add 10 ml of ethylene glycol and 50 ml of deionized water, stir for 6 hours, prepare the slurry, dry the obtained slurry in an oven at 150°C for 12 h, and calcine the dried solid in a muffle furnace at 500°C (heating rate 2°C / min) for 4 h to obtain a three-dimensional flower-shaped structure cesium cerium aluminum composite oxide supported bimetallic CO-V catalyst.

[0092] Comparative example 3: 5% Co-3% V / Ce 0.5 Al 0.9 O 2.35 Preparation of catalyst

[0093] Step one, take the prepared 90 ml of 1 mol / L aluminum nitrate solution and put it into a flask, add ammonia water in a 60°C water bath while stirring to adjust the pH to 10, continue stirring for 30 min, then transfer the mixture to a hydrothermal reaction kettle and react at 130°C for 16 h. The hydrothermal reaction slurry is filtered, washed, dried in an oven at 150°C for 12 h, and then calcined in a muffle furnace at 500°C (heating rate 2°C / min) for 4 h. The obtained solid is ground to powder, 50 ml of 1 mol / L cerium nitrate solution is added, stirred for 6 hours, and a slurry is prepared. Dry the slurry in an oven at 150°C for 12 h, and then calcine in a muffle furnace at 500°C (heating rate 2°C / min) for 4 h. The solid is ground again and placed in a tube furnace under H2 (1.5% hydrogen, helium balance gas) atmosphere at 400°C (heating rate 2°C / min) for 4 h to obtain a hydrogen-treated cesium cerium composite oxide carrier.

[0094] Step two, take 5 g of the cesium cerium composite oxide carrier obtained in step one, grind to powder, add the prepared 2.95 ml of 1 mol / L ammonium metavanadate solution, add 10 ml of ethylene glycol and 50 ml of deionized water, stir for 6 hours, prepare the slurry, dry the obtained slurry in an oven at 150°C for 12 h, and calcine the dried solid in a muffle furnace at 500°C (heating rate 2°C / min) for 4 h to obtain a three-dimensional flower-shaped structure cesium cerium aluminum composite oxide supported bimetallic CO-V catalyst.

[0095] Comparative example 4: 5% Co-3% V / Cs 0.02 Al 0.9 O 1.36 Preparation of catalyst

[0096] Step one, take the 90 ml, 1 mol / L aluminum nitrate solution which has been configured into a flask, in 60 ℃ water bath, stirring, adjusting pH to 10 by adding ammonia water, continue to stir for 30 min, then transfer the mixture to hydrothermal reactor, react at 130 ℃ for 16 h. The hydrothermal reaction slurry is filtered, washed, dried in 150 ℃ oven for 12 h, and then calcined at 500 ℃ (heating rate 2 ℃ / min) in a muffle furnace for 4 h. The obtained solid is ground into powder, 20 ml, 0.1 mol / L cesium nitrate solution is added, stirred for 6 hours, and then the slurry is prepared, dried in 150 ℃ oven for 12 h, and then calcined at 500 ℃ (heating rate 2 ℃ / min) in a muffle furnace for 4 h. The solid is ground again and placed in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 400 ℃ (heating rate 2 ℃ / min) for 4 h to obtain the cesium cerium composite oxide carrier treated by hydrogen.

[0097] Step two, take 5 g of the cesium cerium composite oxide carrier obtained in step one, grind into powder, add 4.24 ml of 1 mol / L cobalt nitrate solution and 2.95 ml of 1 mol / L ammonium metavanadate solution which have been configured, then add 10 ml of ethylene glycol and 50 ml of deionized water, stir for 6 hours, and then prepare the slurry. The obtained slurry is dried in a 150 ℃ oven for 12 h, and then calcined at 500 ℃ (heating rate 2 ℃ / min) in a muffle furnace for 4 h to obtain the three-dimensional flower-shaped structure cesium cerium aluminum composite oxide supported bimetallic CO-V catalyst.

[0098] Comparative example 5: preparation of 5% Co-3% V / Al2O3 catalyst

[0099] Step one, take the 100 ml, 1 mol / L aluminum nitrate solution which has been configured into a flask, in 60 ℃ water bath, stirring, adjusting pH to 10 by adding ammonia water, continue to stir for 30 min, then transfer the mixture to hydrothermal reactor, react at 125 ℃ for 16 h. The hydrothermal reaction slurry is filtered, washed, dried in 120 ℃ oven for 12 h, and then calcined at 500 ℃ (heating rate 2 ℃ / min) in a muffle furnace for 6 h. The obtained solid is ground into powder, and then placed in a tube furnace under H2(1.5% hydrogen, helium balance gas) atmosphere at 500 ℃ (heating rate 2 ℃ / min) for 2 h to obtain the aluminum oxide carrier treated by hydrogen.

[0100] Step two, take 5 g of the alumina support obtained in step one, grind into powder, add the prepared 4.24 ml of 1 mol / L cobalt nitrate solution and 2.95 ml of 1 mol / L ammonium metavanadate solution, then add 10 ml of ethylene glycol and 50 ml of deionized water, stir for 8 hours, prepare the slurry, dry the obtained slurry in an oven at 120°C for 12 h, and then calcine the dried solid in a muffle furnace at 500°C (heating rate 2°C / min) for 6 h, to obtain a three-dimensional flower-like structure alumina supported bimetallic CO-V catalyst.

[0101] Preparation of 5% Co / Al2O3 catalyst

[0102] Step one, take the prepared 100 ml of 1 mol / L aluminum nitrate solution and put it into a flask, adjust the pH to 10 by adding ammonia water while stirring in a 60°C water bath, continue stirring for 30 min, then transfer the mixture to a hydrothermal reaction kettle and react at 125°C for 16 h. The hydrothermal reaction slurry is filtered, washed, dried in an oven at 120°C for 12 h, and then calcined in a muffle furnace at 500°C (heating rate 2°C / min) for 6 h. The obtained solid is ground into powder, then placed in a tube furnace and calcined in H2 (1.5% hydrogen, helium balance gas) atmosphere at 500°C (heating rate 2°C / min) for 2 h to obtain an alumina support treated by hydrogen.

[0103] Step two, take 5 g of the alumina support obtained in step one, grind into powder, add the prepared 4.24 ml of 1 mol / L cobalt nitrate solution, then add 10 ml of ethylene glycol and 50 ml of deionized water, stir for 8 hours, prepare the slurry, dry the obtained slurry in an oven at 120°C for 12 h, and then calcine the dried solid in a muffle furnace at 500°C (heating rate 2°C / min) for 6 h, to obtain a three-dimensional flower-like structure alumina supported monometallic Co catalyst.

[0104] Preparation of 3% V / Al2O3 catalyst

[0105] Step one, take the prepared 100 ml of 1 mol / L aluminum nitrate solution and put it into a flask, adjust the pH to 10 by adding ammonia water while stirring in a 60°C water bath, continue stirring for 30 min, then transfer the mixture to a hydrothermal reaction kettle and react at 125°C for 16 h. The hydrothermal reaction slurry is filtered, washed, dried in an oven at 120°C for 12 h, and then calcined in a muffle furnace at 500°C (heating rate 2°C / min) for 6 h. The obtained solid is ground into powder, then placed in a tube furnace and calcined in H2 (1.5% hydrogen, helium balance gas) atmosphere at 500°C (heating rate 2°C / min) for 2 h to obtain an alumina support treated by hydrogen.

[0106] Step two, take 5 g of alumina carrier obtained in step one, grind to powder, add the prepared 2.95 ml of 1 mol / L ammonium metavanadate solution, add 10 ml of ethylene glycol and 50 ml of deionized water, stir for 8 hours, prepare the slurry, dry the obtained slurry in an oven at 120℃ for 12h, and calcine the dried solid in a muffle furnace at 500℃ (heating rate 2℃ / min) for 6h, to obtain a three-dimensional flower-shaped structure alumina supported single-metal V catalyst.

[0107] Effect implementation example

[0108] The present application adopts a tubular fixed bed reactor for catalyst activity evaluation. The catalyst is sieved to 30-50 mesh, and 0.5 g of the prepared catalyst is loaded in the reaction tube of the fixed bed reactor. The reaction gas composition is 2500 ppm N2O, 0.8% NO, 5% O2, and nitrogen as the balance gas. The flow rate of the reaction gas is 600 mL / min, the space velocity is 60000 h-1, and the activity evaluation temperature range is 500-1000℃. During the catalyst evaluation, the nitrogen oxide content in the outlet gas of the reactor is analyzed after reaching the target temperature and stabilizing for 2 hours, and then the temperature is gradually increased.

[0109] 1. Preparation of 1 mol / L aluminum nitrate solution: weigh 37.5 g of aluminum nitrate nonahydrate solid and dissolve in 83.8 g of deionized water to prepare;

[0110] 2. Preparation of 0.1 mol / L cesium nitrate solution: weigh 2 g of cesium nitrate solid and dissolve in 102.6 g of deionized water to prepare;

[0111] 3. Preparation of 1 mol / L cerium nitrate solution: weigh 43.4 g of cerium nitrate hexahydrate solid and dissolve in 89.2 g of deionized water to prepare;

[0112] 4. Preparation of 1 mol / L cobalt nitrate solution: weigh 29.1 g of cobalt nitrate hexahydrate solid and dissolve in 89.2 g of deionized water to prepare;

[0113] 5. Preparation of 1 mol / L ammonium metavanadate solution: weigh 11.7 g of ammonium metavanadate solid and dissolve in 100 g of deionized water to prepare;

[0114] 6. Preparation of 1 mol / L lanthanum nitrate solution: weigh 43.3 g of lanthanum nitrate hexahydrate solid and dissolve in 89.2 g of deionized water to prepare;

[0115] 7. Preparation of 1 mol / L neodymium nitrate solution: weigh 43.8 g of neodymium nitrate hexahydrate solid and dissolve in 89.2 g of deionized water to prepare;

[0116] Table 1: Nitrous oxide conversion rate results of each example:

[0117]

[0118] In summary, Example 4 is the optimal example, achieving a maximum N2O conversion efficiency of 97%. Compared to the other examples, Example 4 optimizes the ratio of active metal cobalt-vanadium and composite support cesium-cerium, promoting uniform dispersion of metal particles and inhibiting agglomeration, thus accelerating the oxygen transfer process in the redox reaction and obtaining a catalyst with high conversion rate and selectivity. In Example 5, the support was changed to titanium dioxide compared to Example 4. Alumina and titanium dioxide supports have similar functions in this catalyst, improving its stability and durability at high temperatures; no pulverization occurred during prolonged high-temperature operation. In Examples 6 and 7, the rare earth elements were replaced with lanthanum and neodymium, respectively, resulting in catalysts with similar N2O decomposition effects, indicating that rare earth elements have similar properties. Promoters such as Ce, La, and Nd can adjust the work function and oxygen vacancy density of the catalyst, enhancing surface oxygen mobility. In Examples 8 and 9, compared to Example 4, the Cs:Ce:Al molar ratio was adjusted, reducing the Ce content and thus lowering the oxygen vacancy density, affecting the catalyst's promoting effect on the redox reaction and slightly decreasing the N2O conversion efficiency.

[0119] Comparative Examples 1 and 2 showed N2O conversion efficiencies below 66%, indicating a synergistic effect between the active metals cobalt and vanadium in the catalyst. The strong interaction between Co / V oxides weakened the corresponding metal-oxygen bonds, improving the catalytic reductive properties of the active components. Comparative Examples 3 and 4 showed N2O conversion efficiencies below 75%, indicating a strong synergistic effect between the cesium and cerium dual promoters. The composite support obtained by this invention has more oxygen vacancies, which is more conducive to improving catalyst activity and also enhances the catalyst's high-temperature resistance, solving the problem that a single promoter cannot achieve a good catalytic effect. Comparative Examples 5, 6, and 7 showed N2O conversion efficiencies below 50%, indicating an interaction between the active metal and the support. For example, in Example 4, electron transfer occurred between Co and the support promoter Cs. This strong interaction causes Co to exist in the +2 oxidation state during the reaction, which is more beneficial for the adsorption and activation of reactants.

[0120] Catalyst stability evaluation results

[0121] For 5% Co-3% V / Cs 0.02 Ce 0.5 Al 0.9 O 2.36 The catalyst was evaluated for high-temperature stability. The reaction temperature was 850℃, and samples were taken every two hours to analyze the content of the effluent. The results are shown in Table 2 below.

[0122] Time, h 1 3 5 7 9 11 13 15 17 19 21 23 25 Conversion, % 96.3 96.1 96.6 96.5 95.9 95.8 96 95.7 95.6 96.2 96.1 95.5 95.6

[0123] The long-period evaluation experiment is carried out on the catalyst, and the conversion efficiency of N2O of the catalyst can still reach more than 95% after 25h, and no powdering phenomenon of the catalyst is found in the experiment process, indicating that the catalyst has excellent anti-aging performance, can maintain stable catalytic activity in high temperature environment, effectively prolongs the service life of the catalyst, reduces the replacement and maintenance cost, and is suitable for long-period operation of industrial devices.

[0124] Figure 5 The scanning electron microscope pictures of the catalysts of the examples specifically show the scanning electron microscope pictures of the catalysts obtained in Example 1, Example 3, Example 4 and Example 6, and thus it is indicated that the three-dimensional flower-shaped structure catalyst can be obtained by using the synthesis method of the present application, and the growth structure of the catalyst can be finely adjusted by adjusting the proportion of ethylene glycol and pure water.

[0125] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the present application is described in detail with reference to the foregoing examples, for those skilled in the art, it still can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. A composite catalyst for the decomposition of nitrous oxide, characterized in that, The composite catalyst has a three-dimensional flower-like structure, comprising a composite support and an active metal supported on the composite support; The composite carrier is composed of a modifying agent and a carrier oxide; The modifying agent is composed of alkali metal oxides and rare earth metal oxides; The carrier oxide is selected from one of alumina, titanium dioxide, and silicon dioxide; The active metals include cobalt oxide and vanadium oxide.

2. The composite catalyst for nitrous oxide decomposition according to claim 1, characterized in that, The alkali metal oxide is selected from cesium oxides; The rare earth metal oxide is selected from one or more of cerium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, and gadolinium oxide.

3. The composite catalyst for nitrous oxide decomposition according to claim 2, characterized in that, The molar ratio of metal elements in the cesium oxide, the rare earth metal oxide, and the carrier oxide is 0.005–0.05: 0.05–0.5: 0.8–1.

4. The composite catalyst for the decomposition of nitrous oxide according to claim 1, characterized in that, The cobalt element has a mass percentage content of 1-6 wt%; the vanadium element has a mass percentage content of 0.5-5 wt%.

5. The composite catalyst for the decomposition of nitrous oxide according to any one of claims 1-4, characterized in that, The composite carrier is composed of cesium oxide, cerium oxide, and aluminum oxide; specifically as shown in formula (I): Co-V / Cs x Ce y Al z O m Formula (I); In formula (I) above, the mass percentage of Co is 1.5 to 5 wt%; the mass percentage of V is 0.5 to 5 wt%; the value of x is 0.005 to 0.05; the value of y is 0.05 to 0.5; the value of z is 0.8 to 1; and m is the atomic ratio of oxygen required to satisfy the oxidation state of each element.

6. A method for preparing the composite catalyst of claim 5, characterized in that, Includes the following steps: Step 1) Carrier synthesis; Aluminum nitrate solution was placed in a water bath at 40–80°C, and ammonia was added dropwise under stirring until the pH reached 10–11. The solution was then transferred to a hydrothermal reactor and reacted at 110–160°C for 10–24 hours. After filtration, washing with deionized water, drying at 120–150°C for 10–24 hours, and calcining at 500–700°C for 6–8 hours, alumina support was obtained. Step 2) Preparation of modified carrier; The alumina support obtained in step 1) is pulverized, added to a mixed solution containing cesium nitrate and cerium nitrate, stirred for 6-8 hours, dried at 120-150℃ for 10-24 hours and calcined at 500-700℃ for 6-8 hours to obtain the Cs-Ce-Al composite support. Step 3) Reduction process; The carrier obtained in step 2) is reduced and calcined at 200-500℃ for 2-6 hours in a reducing atmosphere to produce the product of step 2); Step 4) Active metal loading; Add cobalt nitrate solution and ammonium metavanadate solution to the carrier treated in step 3), then add a mixed solvent of ethylene glycol and water in a volume ratio of 1 to 5:1, stir to form a slurry, dry at 120 to 150°C for 10 to 24 hours and calcine in static air at 500 to 700°C for 6 to 8 hours to obtain the catalyst.

7. The method according to claim 6, characterized in that, In step 1), the ammonia droplet acceleration rate is 2 to 6 mL / min.

8. The method according to claim 6, characterized in that, In step 3), the reducing atmosphere is selected from H2, CO, or an inert gas containing H2.

9. The method according to claim 6, characterized in that, In step 4), the mass ratio of the mixed solvent of ethylene glycol and water to the carrier is 10 to 30:

1.

10. The method according to claim 6, characterized in that, In step 4), the catalyst has a specific surface area ≥ 100 m². 2 / g.

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