A composite catalyst for simultaneous removal of CO and NO and its preparation method and application x A composite catalyst for simultaneous removal of CO and NO and its preparation method and application

Abstract

The application discloses a composite catalyst for synergistically removing CO and NO x , a preparation method and application thereof, and relates to the technical field of industrial catalysis. The catalyst is obtained by calcining a composite component CuCeM1O x and a molecular sieve component CuM2-SSZ-13 after mechanical ball milling. The CuCeM1O x is prepared by a mechanical ball milling method, and the CuM2-SSZ-13 is prepared by a hydrothermal synthesis method. After the two components are compounded, multi-component micro-uniform mixing and structural synergy are realized. By adjusting the component ratio and process parameters of the two components, the synergistic removal performance of the catalyst in the coupling reaction of CO oxidation and NH3 selective catalytic reduction is significantly improved. The catalyst is suitable for purifying industrial waste gas containing CO and NO x of a steel sintering tail gas and a non-electricity industry, has a simple preparation process, is easy to produce on a large scale, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of industrial catalysis technology, and in particular to a method for the synergistic removal of CO and NO. x Composite catalysts, their preparation methods, and applications. Background Technology

[0002] As a vital economic foundation, the steel industry, while supporting industrial development, is also a major source of air pollutants. In the long-process steel production chain, the sintering step is a key pollutant generator. Its core function is to mix iron ore powder, fuels (coke powder, anthracite, etc.), and fluxes (limestone, quicklime, etc.) and sinter them at high temperatures to provide qualified raw materials for blast furnace ironmaking. However, this high-temperature sintering process generates a large amount of flue gas with complex composition and drastically fluctuating concentrations, including carbon monoxide (CO) and nitrogen oxides (NOx). x These are two typical and highly hazardous pollutants.

[0003] The CO in sintering flue gas mainly originates from the incomplete combustion of fuel, resulting in not only a huge total emission volume but also a wide range of concentration fluctuations; NO x It is mainly produced by the oxidation of nitrogen in fuel and nitrogen in the air under high temperature conditions. It has strong oxidizing and toxic properties, and the large-scale emission of both will pose a serious threat to the ecological environment and human health.

[0004] Traditional sintering flue gas treatment uses independent end-of-pipe treatment technologies, targeting CO and NO. x Purification is carried out separately: For CO, it is mainly converted into CO2 by high-temperature combustion in an ignition and holding furnace at the top of the sintering machine or a dedicated CO incinerator. This method consumes a large amount of energy and has high operating costs; for NO... x Selective catalytic reduction (SCR) technology is commonly used, which involves injecting reducing agents such as ammonia (NH3) or urea into the flue gas to reduce NO within a specific temperature window. x It is reduced to harmless N2.

[0005] However, this segmented treatment model has significant limitations: on the one hand, the CO oxidation process requires a high reaction temperature, while the optimal activity window of the NH3-SCR catalyst often does not match it, resulting in the need for additional complex heat exchange and temperature control devices, which further increases energy consumption and operating costs; on the other hand, the large amount of CO present in the flue gas will compete with NH3 for the active sites of the SCR catalyst, which will not only inhibit the denitrification efficiency, but may also lead to catalyst poisoning and deactivation, affecting the stability of the treatment effect.

[0006] Therefore, it is necessary to develop a method that can efficiently and synergistically remove CO and NO within a single reaction unit and under the same temperature conditions. xThe composite catalyst enables the integrated deep purification of two pollutants, which is of great practical significance for reducing the cost of sintering flue gas treatment in the steel industry, improving purification efficiency, and promoting the green and low-carbon development of the industry. It has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a method for synergistic removal of CO and NO. x This invention provides a composite catalyst, its preparation method, and its application to address the problems existing in the prior art. The composite catalyst provided by this invention can achieve the reaction of CO and NO under the same reaction conditions. x The composite catalyst exhibits highly efficient synergistic removal of CO and NO, and its preparation method is simple, reproducible, and easily scalable. Under the same operating conditions, the composite catalyst of this invention can effectively remove both CO and NO. x It achieves simultaneous and efficient removal, thereby completing the integrated deep purification of sintering flue gas with a simplified process and lower operating costs.

[0008] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention: providing a method for synergistic removal of CO and NO. x The composite catalyst consists of a metal oxide composite component CuCeM1O x It was obtained by mechanical ball milling and then calcining with molecular sieve component CuM2-SSZ-13; The CuCeM1O x It is obtained by mechanical ball milling and calcination using Ce salt, Cu salt and M1 salt as raw materials; The CuM2-SSZ-13 is a Cu and metal M2 modified SSZ-13 molecular sieve; M1 is selected from at least one of Sm, Ni, Fe, Zr and Pr; M2 is selected from at least one of Ce, Mn and Ni.

[0009] Furthermore, the CuCeM1O x In the CuM2-SSZ-13, the mass ratio of Ce:Cu:M1 is (15~40):(4~10):(0.1~2); in the CuM2-SSZ-13, the mass ratio of Cu:M2 is (2~4):(0.2~1.5).

[0010] Furthermore, the CuCeM1O x The mass ratio of CuM2-SSZ-13 is (1-9):(3-7).

[0011] This invention also provides the above-mentioned method for synergistic removal of CO and NO. x The method for preparing the composite catalyst includes the following steps: (1) The Ce salt, Cu salt and M1 salt are mixed and ball-milled in a non-aqueous medium, and then subjected to a first drying treatment and a first calcination treatment to obtain the CuCeM1O. x ; (2) The Cu salt and M2 salt are mixed with silicon source, aluminum source and organic template agent, and subjected to hydrothermal crystallization. After separation and second drying treatment, ammonium exchange is performed, followed by second calcination treatment to obtain CuM2-SSZ-13. (3) The CuCeM1O x The mixture was mixed with CuM2-SSZ-13 and mechanically ball-milled in a dispersion medium, followed by a third drying treatment and a third calcination treatment to obtain the product used for the synergistic removal of CO and NO. x Composite catalyst.

[0012] In step (2), the purpose of ammonium exchange is to exchange the inorganic base cations in the molecular sieve synthesized by hydrothermal crystallization, thereby providing more ion exchange sites.

[0013] Furthermore, the temperature of the first calcination treatment is 400~600 ℃, and the time is 4~8 hours; Furthermore, the hydrothermal crystallization temperature is 140~170 ℃, and the crystallization time is 2~7 days; the second calcination treatment temperature is 500~800 ℃, and the time is 3~8 hours.

[0014] Furthermore, the temperature of the third calcination treatment is 400~600 ℃, and the time is 4~8 hours.

[0015] Furthermore, the non-aqueous medium includes one or more of methanol, ethanol, isopropanol, n-butanol, acetone, and n-hexane; the temperature of the first drying treatment is 50~120 °C, and the time is 6~12 hours.

[0016] Furthermore, the temperature of the second drying process is 90~120 ℃, and the time is 6~12 hours; the concentration of ammonium salt used during ammonium exchange is 0.01~0.5M.

[0017] Furthermore, the dispersion medium includes one or more of deionized water, ethanol, isopropanol, and n-hexane; the temperature of the third drying treatment is 90~120 ℃, and the time is 6~12 hours.

[0018] The second technical solution of the present invention: providing the above-mentioned method for synergistic removal of CO and NO. x Application of composite catalysts in CO catalytic oxidation and / or NH3 selective catalytic reduction (NH3-SCR) reactions.

[0019] The third technical solution of the present invention provides a coupled reactor for CO catalytic oxidation and NH3 selective catalytic reduction, filled with the above-mentioned materials for synergistic removal of CO and NO. x Composite catalyst.

[0020] The fourth technical solution of the present invention provides a system for treating exhaust gas from a steel sintering machine, comprising the above-mentioned coupled reactor for CO catalytic oxidation and NH3 selective catalytic reduction.

[0021] This invention provides a composite catalyst that can react carbon monoxide (CO) and nitrogen oxides (NO) under the same reaction conditions. x The efficient synergistic removal of NO x It exhibits significant advantages in terms of conversion rate, N2 selectivity, and CO conversion rate, successfully verifying the synergistic design concept of "CO oxidation heating and NH3-SCR denitrification".

[0022] The preparation method of the composite catalyst of this invention is simple and has excellent reproducibility, and has the potential for large-scale production. The composite catalyst system has the characteristics of clear structure and adjustable composition, which provides a broad design space for customizing special catalysts for different industrial flue gas scenarios such as steel and coking.

[0023] This invention effectively addresses the challenges posed by multiple pollutants (especially NO) in non-power industries under low-temperature, high-CO-concentration environments. x This breakthrough addresses the technical bottlenecks in collaborative control, providing a highly promising solution for pollution control in related fields.

[0024] The present invention discloses the following technical effects: The composite catalyst of this invention achieves uniform composite and structural synergy of multiple components at the microscale through secondary mechanical ball milling of metal oxide composite components and molecular sieve components. This effectively overcomes the limitations of traditional segmented treatment technologies, enabling efficient and synergistic removal of CO and NO under the same reaction conditions. x It eliminates the need for complex heat exchange and temperature control devices, significantly reducing energy consumption and operating costs.

[0025] The composite catalyst of this invention has both excellent CO oxidation activity and NH3 selective catalytic reduction performance. The heat released by CO oxidation can create favorable temperature conditions for the denitrification reaction, forming a positive synergistic effect, while avoiding the competitive inhibition of CO on the active sites of the SCR catalyst.

[0026] The preparation method of this invention is simple, reproducible, and has adjustable components. It allows for the customization of specialized catalysts for different industrial flue gas scenarios, and is suitable for exhaust gases from steel sintering machines and various CO and NO-containing gases in non-electric industries. xThe industrial waste gas purification technology provides an efficient solution for the synergistic control of multiple pollutants in non-power industries, and has broad application prospects. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The X-ray diffraction (XRD) patterns are those of the catalysts prepared in Examples 1-5 and Comparative Examples 1-2 of this invention.

[0029] Figure 2 The catalysts prepared in Examples 1-3 and Comparative Examples 1-3 in the CO oxidation coupled with NH3-SCR reaction for NO x Conversion rate (a), N2 selectivity (b), and CO conversion rate (c). Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0036] First aspect of the present invention: providing a method for synergistic removal of CO and NO x The composite catalyst consists of a metal oxide composite component CuCeM1O x It was obtained by mechanical ball milling and then calcining with molecular sieve component CuM2-SSZ-13; The CuCeM1O x It is obtained by mechanical ball milling and calcination using Ce salt, Cu salt and M1 salt as raw materials; The CuM2-SSZ-13 is a Cu and metal M2 modified SSZ-13 molecular sieve; M1 is selected from at least one of Sm, Ni, Fe, Zr and Pr; M2 is selected from at least one of Ce, Mn and Ni.

[0037] Furthermore, the CuCeM1O x In the CuM2-SSZ-13, the mass ratio of Ce:Cu:M1 is (15~40):(4~10):(0.1~2); in the CuM2-SSZ-13, the mass ratio of Cu:M2 is (2~4):(0.2~1.5).

[0038] Furthermore, the CuCeM1O x The mass ratio of CuM2-SSZ-13 is (1-9):(3-7).

[0039] Second aspect of the present invention: providing the above-mentioned method for synergistic removal of CO and NO. x The method for preparing the composite catalyst includes the following steps: (1) Cerium (Ce) salt, copper (Cu) salt and auxiliary metal (M1) salt are placed in a ball milling jar along with an appropriate amount of zirconium oxide ball milling media in a certain proportion. An appropriate amount of non-aqueous media is added as a process control agent. The mixture is ball milled at 100-500 rpm for 1-6 hours at room temperature. The precursors are induced to undergo solid-phase reaction or mechanical alloying by high-energy mechanical force to achieve uniform mixing at the molecular level.

[0040] (2) After ball milling, the resulting slurry is dried to completely remove the solvent, resulting in a loose precursor powder. Finally, the powder is placed in a muffle furnace for calcination to completely convert the metal salt into the corresponding oxide complex. After natural cooling, highly dispersible CuCeM1O can be obtained. x Composite materials.

[0041] (3) Dissolve copper salt and auxiliary metal (M2) salt in an aqueous solution containing complexing agent in a certain proportion, stir thoroughly to form CuM2 complex; then add KOH, NaAlO2, N,N,N-trimethyl-1-adamantyl ammonium hydroxide and tetraethyl orthosilicate in sequence, stir evenly to obtain initial gel.

[0042] (4) The initial gel obtained in step (3) is subjected to hydrothermal crystallization. After the reaction is completed, the solid product is collected, filtered, washed and dried, and then ammonium exchange is performed. Finally, the organic template agent is removed by calcination to obtain CuM2-SSZ-13 molecular sieve.

[0043] (5) CuCeM1O x The composite material and CuM2-SSZ-13 molecular sieve were placed in a ball mill jar at a certain ratio, along with an appropriate amount of zirconia microspheres and a small amount of dispersion medium. The mixture was ball-milled at 100-500 rpm for 0.5-2 hours at room temperature. After ball milling, the resulting slurry was dried and calcined to finally obtain CuCeM1O. x / CuM2-SSZ-13 composite catalyst.

[0044] Furthermore, the temperature of the first calcination treatment is 400~600 ℃, and the time is 4~8 hours; Furthermore, the hydrothermal crystallization temperature is 140~170 ℃, and the crystallization time is 2~7 days; the second calcination treatment temperature is 500~800 ℃, and the time is 3~8 hours.

[0045] Furthermore, the temperature of the third calcination treatment is 400~600 ℃, and the time is 4~8 hours.

[0046] Furthermore, the non-aqueous medium includes one or more of methanol, ethanol, isopropanol, n-butanol, acetone, and n-hexane; the temperature of the first drying treatment is 50~120 °C, and the time is 6~12 hours.

[0047] Furthermore, the temperature of the second drying process is 90~120 ℃, and the time is 6~12 hours; the concentration of ammonium salt used during ammonium exchange is 0.01~0.5M.

[0048] Furthermore, the dispersion medium includes one or more of deionized water, ethanol, isopropanol, and n-hexane; the temperature of the third drying treatment is 90~120 ℃, and the time is 6~12 hours.

[0049] Third aspect of the present invention: providing the above-mentioned method for synergistic removal of CO and NO. x Application of composite catalysts in CO catalytic oxidation and / or NH3 selective catalytic reduction (NH3-SCR) reactions.

[0050] Fourth aspect of the present invention: Provides a coupled reactor for CO catalytic oxidation and NH3 selective catalytic reduction, packed with the above-mentioned reactor for synergistic removal of CO and NO. x Composite catalyst.

[0051] Fifth aspect of the present invention: A system for treating exhaust gas from a steel sintering machine is provided, comprising the above-mentioned coupled reactor for CO catalytic oxidation and NH3 selective catalytic reduction.

[0052] Example 1 This embodiment provides a CuCeSmO x The preparation method of the CuCe-SSZ-13 composite catalyst includes the following steps: (1) According to the metal mass ratio of Ce:Cu:Sm of 30:7:0.5, accurately weigh 12.08 g of cerium nitrate hexahydrate, 3.46 g of copper nitrate trihydrate and 0.19 g of samarium nitrate hexahydrate, and place them in a ball mill jar; add zirconia grinding balls as the ball milling medium and add an appropriate amount of ethanol as a process control agent. Seal the ball mill jar and ball mill at 300 rpm for 4 hours at room temperature to obtain a uniform slurry.

[0053] (2) The slurry obtained in step (1) was dried in an oven at 70 °C for 10 hours to obtain a dried precursor. The precursor was then transferred to a muffle furnace and calcined at 400 °C for 8 hours. After calcination, the precursor was allowed to cool naturally to room temperature to obtain CuCeSmO. x Composite oxide powder.

[0054] (3) According to the metal mass ratio of Cu:Ce of 3:0.5, accurately weigh 0.91 g of copper nitrate trihydrate and 0.13 g of cerium nitrate hexahydrate, and dissolve them together in an aqueous solution containing tetrasodium ethylenediaminetetraacetate to form a clear metal complex solution. Then, add 0.72 g of potassium hydroxide, 0.52 g of sodium aluminate, 22 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide and 26.62 g of tetraethyl orthosilicate in sequence, and stir continuously for 2 hours to form a uniform initial gel.

[0055] (4) The initial gel was transferred to a polystainless steel hydrothermal reactor and crystallized at 150 °C for 4 days. After the reaction, the solid product was filtered and repeatedly washed with deionized water until the filtrate was neutral. The washed solid was dried at 100 °C for 8 hours to obtain molecular sieve powder. Subsequently, the molecular sieve powder was placed in a 0.1 mol / L ammonium chloride solution and ion exchanged at 80 °C for 5 hours. After the exchange was completed, it was filtered and washed again and dried at 100 °C. Finally, the dried sample was calcined at 600 °C for 5 hours to completely remove the organic template agent and obtain CuCe-SSZ-13 molecular sieve.

[0056] (5) According to CuCeSmO x The mass ratio of CuCe-SSZ-13 to CuCe is 4:6. 4 g of CuCeSmO obtained in step (2) is accurately weighed. x The composite material and 6 g of CuCe-SSZ-13 molecular sieve prepared in step (4) were placed in a ball mill jar; zirconium oxide grinding balls and an appropriate amount of ethanol were added as dispersion media. The ball mill jar was sealed and ball milled at 300 rpm for 1 hour at room temperature. After ball milling, the resulting slurry was dried at 90 °C for 10 hours, and then the dried solid powder was placed in a muffle furnace and calcined at 500 °C for 6 hours to finally obtain CuCeSmO x / CuCe-SSZ-13 composite catalyst.

[0057] Comparative Example 1 This comparative example provides a catalyst, which is the CuCeSmO prepared in Example 1. x Composite oxide powder.

[0058] Comparative Example 2 This comparative example provides a catalyst, which is the CuCe-SSZ-13 molecular sieve prepared in Example 1.

[0059] Comparative Example 3 This comparative example provides a CuCeSmO prepared by a physical mixing method. x The preparation process of the CuCe-SSZ-13 composite catalyst includes the following steps: Steps (1) to (4) are the same as in Example 1.

[0060] (5) According to CuCeSmO x The mass ratio of CuCe-SSZ-13 to CuCe is 4:6. 4 g of CuCeSmO obtained in step (2) is accurately weighed. xThe composite material and 6 g of CuCe-SSZ-13 molecular sieve prepared in step (4) were placed in an agate mortar. The two were physically mixed by manual grinding for 30 minutes at room temperature until homogeneous. The homogeneous powder was then transferred to a muffle furnace and calcined at 500 °C for 6 hours to finally obtain CuCeSmO. x / CuCe-SSZ-13 composite catalyst.

[0061] Example 2 This embodiment provides a CuCeNiO x The preparation method of the CuMn-SSZ-13 composite catalyst includes the following steps: (1) According to the mass ratio of Ce:Cu:Ni metal of 20:5:0.3, accurately weigh 8.68 g of cerium nitrate hexahydrate, 1.93 g of copper nitrate trihydrate and 0.12 g of nickel nitrate hexahydrate and place them in a ball mill jar; add zirconium oxide ball milling media and an appropriate amount of methanol as process control agent to the jar, seal the ball mill jar, and ball mill at 400 rpm for 2 hours at room temperature.

[0062] (2) After ball milling, the resulting slurry was dried in an oven at 60 °C for 12 hours to obtain a dried precursor. Subsequently, the dried precursor powder was placed in a muffle furnace and calcined at 450 °C for 7 hours. After calcination, the sample was allowed to cool naturally to room temperature in the furnace to obtain CuCeNiO. x Composite material powder.

[0063] (3) According to the Cu:Mn metal mass ratio of 2.5:0.4, accurately weigh 0.85 g of copper nitrate trihydrate and 0.18 g of manganese nitrate tetrahydrate, and dissolve them together in an aqueous solution containing triethylenetetramine to form a clear metal complex solution. Subsequently, add 0.65 g of potassium hydroxide, 0.48 g of sodium aluminate, 20 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide and 25.5 g of tetraethyl orthosilicate to the solution in sequence, and stir continuously for 2.5 hours to form a uniform initial gel.

[0064] (4) The initial gel was transferred to a hydrothermal reactor and crystallized in an oven at 155 °C for 5 days. After the reaction, the solid product was filtered and repeatedly washed with deionized water until the filtrate was neutral. The washed solid product was dried at 90 °C for 12 hours to obtain molecular sieve powder. The dried molecular sieve powder was placed in a 0.3 mol / L ammonium chloride solution and ion-exchanged at 80 °C for 5 hours. After the ion exchange was completed, it was filtered and washed again and dried at 90 °C. Finally, the ammonium-exchanged molecular sieve was calcined at 550 °C for 5 hours to remove the organic template agent, and CuMn-SSZ-13 molecular sieve was obtained.

[0065] (5) According to CuCeNiO x The mass ratio of CuMn-SSZ-13 is 2:6. Accurately weigh 2.5g of the prepared CuCeNiO2 as described above. x The composite material and 7.5 g of CuMn-SSZ-13 molecular sieve were placed in a ball mill jar. Zirconia ball milling media and an appropriate amount of isopropanol were added as dispersion media. The ball mill jar was sealed and ball milled at 250 rpm for 2 hours at room temperature. After ball milling, the resulting slurry was dried at 100 °C for 8 hours. Finally, the dried solid powder was placed in a muffle furnace and calcined at 550 °C for 5 hours to obtain CuCeNiO. x / CuMn-SSZ-13 composite catalyst.

[0066] Example 3 This embodiment provides a CuCeFeO x The preparation method of the CuNi-SSZ-13 composite catalyst includes the following steps: (1) Weigh 15.25 g of cerium nitrate hexahydrate, 4.12 g of copper nitrate trihydrate and 0.48 g of ferric nitrate nonahydrate precisely into a ball mill jar according to the mass ratio of Ce:Cu:Fe metals of 38:8:1.2. Add zirconium oxide ball milling media and an appropriate amount of acetone as a process control agent to the jar, seal the ball mill jar, and ball mill at 350 rpm for 1.5 hours at room temperature.

[0067] (2) After ball milling, the resulting slurry was dried in an oven at 60 °C for 12 hours. Then, the dried precursor powder was placed in a muffle furnace and calcined at 500 °C for 4 hours. After calcination, the sample was allowed to cool naturally to room temperature inside the furnace to obtain CuCeFeO. x Composite material powder.

[0068] (3) According to the Cu:Ni metal mass ratio of 3.2:0.9, accurately weigh 1.05 g of copper nitrate trihydrate and 0.32 g of nickel nitrate hexahydrate, and dissolve them together in an aqueous solution containing triethylamine to form a clear metal complex solution. Subsequently, add 0.78 g of potassium hydroxide, 0.58 g of sodium aluminate, 24 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide and 28.35 g of tetraethyl orthosilicate to the solution in sequence, and stir continuously for 4 hours to form a uniform initial gel.

[0069] (4) The initial gel was transferred to a hydrothermal reactor and crystallized in an oven at 165 °C for 3 days. After the reaction, the solid product was filtered and washed repeatedly with deionized water until the filtrate was neutral. The washed solid product was dried at 110 °C for 6 hours. The dried molecular sieve powder was placed in a 0.5 mol / L ammonium chloride solution and ion-exchanged at 80 °C for 5 hours. After the ion exchange was completed, it was filtered and washed again and dried at 110 °C. Finally, the ammonium-exchanged molecular sieve was calcined at 500 °C for 6 hours to remove the organic template agent, yielding CuNi-SSZ-13 molecular sieve.

[0070] (5) According to CuCeFeO x The mass ratio of CuNi-SSZ-13 is 5:5. Accurately weigh 5 g of the CuCeFeO prepared above. x The composite material and 5 g of CuNi-SSZ-13 molecular sieve were placed in a ball mill jar. Zirconia ball milling media and an appropriate amount of n-hexane were added as dispersion media. The ball mill jar was sealed and ball milled at 400 rpm for 0.5 hours at room temperature. After ball milling, the resulting slurry was dried at 120 °C for 6 hours. Finally, the dried solid powder was placed in a muffle furnace and calcined at 450 °C for 5 hours to obtain CuCeFeO. x / CuNi-SSZ-13 composite catalyst.

[0071] Example 4 This embodiment provides a CuCeZrO x The preparation method of the CuCe-SSZ-13 composite catalyst includes the following steps: (1) Accurately weigh 10.42 g of cerium nitrate hexahydrate, 2.96 g of copper nitrate trihydrate, and 0.26 g of zirconium nitrate pentahydrate into a ball mill jar according to a Ce:Cu:Zr metal mass ratio of 25:6:0.8. Add zirconium oxide ball milling media and an appropriate amount of n-butanol as a process control agent to the jar, seal the ball mill jar, and ball mill at 250 rpm for 3 hours at room temperature.

[0072] (2) After ball milling, the resulting slurry was dried in an oven at 120 °C for 6 hours. Then, the dried precursor powder was placed in a muffle furnace and calcined at 500 °C for 7 hours. After calcination, the sample was allowed to cool naturally to room temperature inside the furnace to obtain CuCeZrO. x Composite material powder.

[0073] (3) Accurately weigh 0.98 g of copper nitrate trihydrate and 0.21 g of cerium nitrate hexahydrate according to the Cu:Ce metal mass ratio of 2.8:0.7, and dissolve them together in an aqueous solution containing tetrasodium ethylenediaminetetraacetate to form a clear metal complex solution. Subsequently, add 0.68 g of potassium hydroxide, 0.48 g of sodium aluminate, 20.5 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide and 25.80 g of tetraethyl orthosilicate to the solution in sequence, and stir continuously for 3 hours to form a uniform initial gel.

[0074] (4) The initial gel was transferred to a hydrothermal reactor and crystallized in an oven at 145 °C for 6 days. After the reaction, the solid product was filtered and washed repeatedly with deionized water until the filtrate was neutral. The washed solid product was dried at 100 °C for 4 hours. The dried molecular sieve powder was placed in a 0.08 mol / L ammonium chloride solution and ion-exchanged at 80 °C for 5 hours. After the exchange was completed, it was filtered and washed again and dried at 100 °C. Finally, the ammonium-exchanged molecular sieve was calcined at 650 °C for 4 hours to remove the organic template agent, yielding CuCe-SSZ-13 molecular sieve.

[0075] (5) According to CuCeZrO x The mass ratio of CuCe-SSZ-13 is 3:7. Accurately weigh 3 g of the prepared CuCeZrO2 as described above. x The composite material and 7 g of CuCe-SSZ-13 molecular sieve were placed in a ball mill jar. Zirconia ball milling media and an appropriate amount of deionized water were added as dispersion media. The ball mill jar was sealed and ball milled at 150 rpm for 2 hours at room temperature. After ball milling, the resulting slurry was dried at 120 °C for 4 hours. Finally, the dried solid powder was placed in a muffle furnace and calcined at 600 °C for 4 hours to obtain CuCeZrO. x / CuCe-SSZ-13 composite catalyst.

[0076] Example 5 This embodiment provides a CuCePrO x The preparation method of the CuMn-SSZ-13 composite catalyst includes the following steps: (1) According to the mass ratio of Ce:Cu:Pr metals of 38:9:1.8, accurately weigh 17.82 g of cerium nitrate hexahydrate, 5.28 g of copper nitrate trihydrate and 0.85 g of praseodymium nitrate hexahydrate and place them in a ball mill jar. Add zirconium oxide ball milling media and an appropriate amount of n-hexane as a process control agent to the jar, seal the ball mill jar, and ball mill at 200 rpm for 2 hours at room temperature.

[0077] (2) After ball milling, the resulting slurry was dried in an oven at 80 °C for 6 hours. Then, the dried precursor powder was placed in a muffle furnace and calcined at 600 °C for 5 hours. After calcination, the sample was allowed to cool naturally to room temperature inside the furnace to obtain CuCePrO. x Composite material powder.

[0078] (3) According to the Cu:Mn metal mass ratio of 3.8:1.4, accurately weigh 1.32 g of copper nitrate trihydrate and 0.62 g of manganese nitrate tetrahydrate, and dissolve them together in an aqueous solution containing disodium ethylenediaminetetraacetate to form a clear metal complex solution. Subsequently, add 0.85 g of potassium hydroxide, 0.62 g of sodium aluminate, 26 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide and 30.25 g of tetraethyl orthosilicate to the solution in sequence, and stir continuously for 4 hours to form a uniform initial gel.

[0079] (4) The initial gel was transferred to a hydrothermal reactor and crystallized in an oven at 170 °C for 3 days. After the reaction, the solid product was filtered and washed repeatedly with deionized water until the filtrate was neutral. The washed solid product was dried at 120 °C for 6 hours. The dried molecular sieve powder was placed in a 0.3 mol / L ammonium chloride solution and ion-exchanged at 80 °C for 5 hours. After the ion exchange was completed, the product was filtered and washed again and dried at 120 °C. Finally, the ammonium-exchanged molecular sieve was calcined at 650 °C for 3 hours to remove the organic template agent, yielding CuMn-SSZ-13 molecular sieve.

[0080] (5) According to CuCePrO x The mass ratio of CuMn-SSZ-13 is 8:2. Accurately weigh 8 g of the CuCePrO prepared above. x The composite material and 2 g of CuMn-SSZ-13 molecular sieve were placed in a ball mill jar. Zirconia ball milling media and an appropriate amount of ethanol were added as dispersion media. The ball mill jar was sealed and ball milled at 350 rpm for 1 hour at room temperature. After ball milling, the resulting slurry was dried at 90 °C for 7 hours. Finally, the dried solid powder was placed in a muffle furnace and calcined at 400 °C for 8 hours to obtain CuCePrO. x / CuMn-SSZ-13 composite catalyst.

[0081] XRD tests were performed on the catalysts prepared in Examples 1-5 and Comparative Examples 1-2, and the results are as follows: Figure 1 As shown.

[0082] Example 6 CuCeNiO xThe preparation method of the CuCe-SSZ-13 composite catalyst includes the following steps: (1) According to the mass ratio of Ce:Cu:Ni metal of 20:5:0.2, accurately weigh 10.42 g of cerium nitrate hexahydrate, 2.96 g of copper nitrate trihydrate and 0.08 g of nickel nitrate hexahydrate and place them in a ball mill jar. Add zirconium oxide ball milling media and an appropriate amount of acetone as process control agent to the jar, seal the ball mill jar, and ball mill at 250 rpm for 1.5 hours at room temperature.

[0083] (2) After ball milling, the resulting slurry was dried in an oven at 85 °C for 10 hours. Subsequently, the dried precursor powder was placed in a muffle furnace and calcined at 450 °C for 6 hours. After calcination, the sample was allowed to cool naturally to room temperature in the furnace to obtain CuCeNiO. x Composite material powder.

[0084] (3) Accurately weigh 0.98 g of copper nitrate trihydrate and 0.21 g of cerium nitrate hexahydrate according to the Cu:Ce metal mass ratio of 2.8:0.7, and dissolve them together in an aqueous solution containing tetrasodium ethylenediaminetetraacetate to form a clear metal complex solution. Subsequently, add 0.68 g of potassium hydroxide, 0.48 g of sodium aluminate, 20.5 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide and 25.8 g of tetraethyl orthosilicate to the solution in sequence, and stir continuously for 2 hours to form a uniform initial gel.

[0085] (4) The initial gel was transferred to a hydrothermal reactor and crystallized in an oven at 140 °C for 7 days. After the reaction, the solid product was filtered and repeatedly washed with deionized water until the filtrate was neutral. The washed solid product was dried at 110 °C for 7 hours to obtain molecular sieve powder. The dried molecular sieve powder was placed in a 0.15 mol / L ammonium chloride solution and ion-exchanged at 80 °C for 5 hours. After the exchange was completed, it was filtered and washed again and dried at 110 °C. Finally, the ammonium-exchanged molecular sieve was calcined at 600 °C for 5 hours to remove the organic template agent, and CuCe-SSZ-13 molecular sieve was obtained.

[0086] (5) According to CuCeNiO x The mass ratio of CuCe-SSZ-13 is 3:7. Accurately weigh 3.0 g of the prepared CuCeNiO2 as described above. xThe composite material and 7.0 g of CuCe-SSZ-13 molecular sieve were placed in a ball mill jar. Zirconia ball milling media and isopropanol were added as dispersion media. The ball mill jar was sealed and ball milled at 200 rpm for 2 hours at room temperature. After ball milling, the resulting slurry was dried at 100 °C for 6 hours. Finally, the dried solid powder was placed in a muffle furnace and calcined at 600 °C for 5 hours to obtain CuCeNiO. x / CuCe-SSZ-13 composite catalyst.

[0087] Example 7 The only difference from Example 6 is that the mass ratio of Ce:Cu:Ni metal is 20:5:0.5, and the corresponding raw material mass ratio is: 10.42 g cerium nitrate hexahydrate, 2.96 g copper nitrate trihydrate and 0.2 g nickel nitrate hexahydrate.

[0088] Example 8 The only difference from Example 6 is that the mass ratio of Ce:Cu:Ni metal is 20:5:1.0, and the corresponding raw material mass ratio is: 10.42 g cerium nitrate hexahydrate, 2.96 g copper nitrate trihydrate and 0.4 g nickel nitrate hexahydrate.

[0089] Example 9 The only difference from Example 6 is that the mass ratio of Ce:Cu:Ni metal is 20:5:1.8, and the corresponding raw material mass ratio is: 10.42 g cerium nitrate hexahydrate, 2.96 g copper nitrate trihydrate and 0.72 g nickel nitrate hexahydrate.

[0090] Example of effect verification: To verify the catalytic performance of the prepared catalyst in the coupled reaction of CO catalytic oxidation and NH3-SCR, the catalysts of Examples 1-3 and Comparative Examples 1-3 were tested in a fixed-bed reactor under the following conditions: catalyst loading was 0.25 g (particle size 60-80 mesh). The catalyst described in this invention is suitable for CO concentrations of 200-6000 ppm and NO concentrations of 1-3. x Under typical industrial waste gas conditions with concentrations of 200–1500 ppm, this test can effectively treat actual flue gas within this concentration range. The simulated flue gas composition used in this performance test was: 500 ppm NH3 and 500 ppm NO. x 5000 ppm CO, 5% O2, with N2 as the balance gas.

[0091] The test results of the performance of the CO catalytic oxidation coupled reaction with NH3-SCR are as follows: Figure 2 As shown in the figure. The test results indicate that the coupling reaction performance of different catalysts varies significantly, and the composite structure design exhibits a clear advantage: Throughout the entire test temperature range, CuCeSmO in Example 1 x NO from CuCe-SSZ-13 catalyst x The conversion rates were all superior to those of the catalysts in Comparative Examples 1-3. Comparative Example 1's CuCeSmO x The lowest activity was observed in CuCe-SSZ-13 (Comparative Example 2) and CuCeSmO (Comparative Example 3). x Although the CuCe-SSZ-13 (physical mixture) exhibits some SCR activity, it does not reach the high level of Example 1. Regarding N2 selectivity, the catalysts of Example 1 are all superior to Comparative Examples 1-3, while the CuCeSmO catalyst of Comparative Example 1... x Overall selectivity was poor. Regarding CO oxidation performance, the catalysts of Example 1, Comparative Example 1, and Comparative Example 3 all achieved complete CO conversion after reaching a certain temperature. Example 1 showed stronger CO oxidation ability at low temperatures, but its low-temperature CO conversion rate was lower than that of Comparative Example 1. (Combined NO...) x In terms of conversion rate, N2 selectivity, and CO oxidation performance, Example 1 is the catalyst with the most balanced overall performance, achieving a combination of high activity, high selectivity, and good stability across the entire temperature window.

[0092] Comparing Examples 1-3, it can be seen that the low-temperature NO conversion rate of Example 2 is significantly better than that of Examples 1 and 3, indicating that its low-temperature activity is more prominent; while the low-temperature activity of Example 3 is between the two. Regarding N2 selectivity, Examples 1-3 have near 100% selectivity in the low-temperature region, with a slight decrease in the medium- and high-temperature ranges. As for CO conversion rate, all three achieved complete conversion over a relatively wide temperature range, with Example 2 exhibiting the strongest low-temperature CO oxidation ability.

[0093] Overall, different catalysts exhibited significant performance differences in the coupled NH3-SCR and CO oxidation reactions, demonstrating the regulatory effect of active components, structure, or preparation methods on catalytic performance. In practical applications, a suitable catalyst system can be selected based on the target temperature window and specific requirements for activity and selectivity.

[0094] In summary, the composite catalyst developed in this invention exhibits superior overall performance. By structurally combining a highly efficient CO oxidation component with an SCR catalyst, high NO content is achieved. xThe design achieves a synergistic improvement in conversion rate, excellent N2 selectivity, and strong low-temperature CO oxidation activity. It utilizes the heat released from the CO oxidation reaction to promote the SCR reaction, forming a positive synergistic effect, thus fully meeting the performance requirements of complex coupled reaction systems. In contrast, the single-component catalyst in Comparative Example 1 has insufficient SCR catalytic function; the single SCR catalyst in Comparative Example 2 is limited by its weak CO oxidation capacity; and although Comparative Example 3 uses a physical mixing method, its SCR activity and CO oxidation activity are both lower than those of the catalyst prepared by ball milling. These comparative systems all fail to meet the comprehensive requirements of coupled reactions for multifunctional synergy. These results further confirm the significant necessity and superiority of composite structure design in systems involving multiple reaction couplings.

[0095] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for synergistic removal of CO and NO x The composite catalyst, characterized in that, Composed of metal oxide composite component CuCeM1O x It was obtained by mechanical ball milling and then calcining with molecular sieve component CuM2-SSZ-13; The CuCeM1O x It is obtained by mechanical ball milling and calcination using Ce salt, Cu salt and M1 salt as raw materials; The CuM2-SSZ-13 is a Cu and M2 modified SSZ-13 molecular sieve; M1 is selected from at least one of Sm, Ni, Fe, Zr and Pr; M2 is selected from at least one of Ce, Mn and Ni.

2. The method for synergistic removal of CO and NO according to claim 1 x The composite catalyst, characterized in that, The CuCeM1O x In the CuM2-SSZ-13, the mass ratio of Ce:Cu:M1 is (15~40):(4~10):(0.1~2); in the CuM2-SSZ-13, the mass ratio of Cu:M2 is (2~4):(0.2~1.5).

3. The method for synergistic removal of CO and NO according to claim 1 x The composite catalyst, characterized in that, The CuCeM1O x The mass ratio of CuM2-SSZ-13 is (1-9):(3-7).

4. The method for synergistic removal of CO and NO as described in any one of claims 1-3 x The method for preparing the composite catalyst is characterized in that, Includes the following steps: (1) The Ce salt, Cu salt and M1 salt are mixed and ball-milled in a non-aqueous medium, and then subjected to a first drying treatment and a first calcination treatment to obtain the CuCeM1O. x ; (2) The Cu salt and M2 salt are mixed with silicon source, aluminum source and organic template agent, and subjected to hydrothermal crystallization. After separation and second drying treatment, ammonium exchange is performed, followed by second calcination treatment to obtain CuM2-SSZ-13. (3) The CuCeM1O x The mixture was mixed with CuM2-SSZ-13 and mechanically ball-milled in a dispersion medium, followed by a third drying treatment and a third calcination treatment to obtain the product used for the synergistic removal of CO and NO. x Composite catalyst.

5. The preparation method according to claim 4, characterized in that, The temperature of the first calcination treatment is 400~600℃, and the time is 4~8 hours.

6. The preparation method according to claim 4, characterized in that, The hydrothermal crystallization temperature is 140~170 ℃, and the crystallization time is 2~7 days; the second calcination treatment temperature is 500~800 ℃, and the time is 3~8 hours.

7. The preparation method according to claim 4, characterized in that, The third calcination treatment is carried out at a temperature of 400~600℃ for 4~8 hours.

8. The method for synergistic removal of CO and NO as described in any one of claims 1-3 x Application of composite catalysts in the coupled reaction of CO catalytic oxidation and NH3 selective catalytic reduction.

9. A coupled reactor for CO catalytic oxidation and NH3 selective catalytic reduction, characterized in that, Filled with the product as described in any one of claims 1-3 for the synergistic removal of CO and NO. x Composite catalyst.

10. A system for treating exhaust gas from a steel sintering machine, characterized in that, It includes the CO catalytic oxidation and NH3 selective catalytic reduction coupled reactor as described in claim 9.

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