A catalyst for synergistic treatment of CO and VOCs, its preparation method and application

Abstract

This invention provides a catalyst for the synergistic treatment of CO and VOCs, its preparation method, and its application. The catalyst comprises a matrix and a first coating and a second coating sequentially supported on the matrix. The first coating comprises a first support, a first active component, a sulfur inhibitor, and a first binder. The first support comprises an MFI hierarchical porous molecular sieve, and the first active component comprises ruthenium and platinum. The second coating comprises a second support, a second active component, and a second binder. The second support comprises titanium dioxide, and the second active component comprises chromium oxide and molybdenum oxide. The catalyst provided by this invention employs a dual-coating design. The first coating solves the problems of catalyst resistance to water gradients, susceptibility to sulfur, and chlorine poisoning. The second coating can oxidize low-valence sulfur compounds such as hydrogen sulfide, carbonyl sulfide, and carbon disulfide in flue gas to high-valence sulfur dioxide and rapidly desorb them, while also protecting the inner coating, significantly extending the catalyst's service life.

Description

Technical Field

[0001] This invention belongs to the field of flue gas treatment technology, and relates to a catalyst for the synergistic treatment of CO and VOCs, its preparation method and application. Background Technology

[0002] As my country's efforts to prevent and control air pollution continue to deepen, the emissions of some unconventional pollutants have gradually attracted attention, with carbon monoxide (CO) and volatile organic compounds (VOCs) becoming key concerns.

[0003] Solid waste disposal, chemical, steel, and non-ferrous smelting industries are major emitters of carbon monoxide and VOCs. Currently, catalytic oxidation processes are mainly used to reduce emissions. However, even after desulfurization, their flue gas still contains a certain amount of sulfur-containing substances (organic sulfur such as carbonyl sulfide and thiols cannot be reduced by desulfurization) and chlorine-containing substances. These poisoning substances can significantly shorten the lifespan of catalysts. Therefore, there is an urgent need for a highly resistant (water-resistant, sulfur-resistant, chlorine-resistant) integrated high-efficiency catalyst for the synergistic treatment of carbon monoxide and VOCs.

[0004] CN118698571A discloses a method for preparing and applying a manganese-based core-shell denitrification catalyst for the combined removal of CO and VOCs. The catalyst uses manganese dioxide as the active material and iron, copper, and phosphorus as auxiliary agents. The preparation process involves first dispersing manganese dioxide in a mixture of ethanol and water, then sequentially adding a phosphorus precursor, urea, an iron-copper precursor solution, and an ethanol solution of tetraethyl orthosilicate. The precipitate produced by the reaction is then separated, purified, and the reaction product is obtained. Finally, the reaction product is calcined to obtain the manganese-based core-shell denitrification catalyst. Although this catalyst possesses the ability to synergistically treat multiple pollutants, it uses manganese oxide as the active material. Manganese oxide is a commonly used descaling agent for hydrogen sulfide and carbonyl sulfide. It reacts with hydrogen sulfide to form manganese sulfide, and the catalyst will rapidly deactivate in the presence of hydrogen sulfide.

[0005] CN117983243A discloses a sulfur-resistant metal-based catalytic oxidation catalyst, its preparation method, and its application. The catalyst uses at least one of Pt, Rh, Ru, and Pd as the active material, and one or more of metal oxides BeO, Al2O3, CeO2, Cr2O3, MnO2, V2O5, and ZnO as the promoter, with FeCrAl alloy as the support. The preparation process involves first fabricating a FeCrAl alloy honeycomb matrix with a regular structure, then uniformly coating the noble metal active material and oxides onto the surface of the FeCrAl alloy honeycomb matrix, followed by drying and calcination to obtain an intermediate sample. Finally, SiO2 and TiO2 are coated onto the surface of the intermediate sample as protective layers, followed by drying and calcination to obtain the catalyst. This catalyst exhibits excellent performance, but its sulfur resistance mainly relies on the inhibition of acidic sulfide adsorption by acidic sites, failing to address the poisoning effects of neutral sulfides such as carbon disulfide and organic sulfur.

[0006] Therefore, it is of great significance to provide a catalyst for the synergistic treatment of CO and VOCs that combines oxidation performance with sulfur and chlorine resistance and has a simple preparation method. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a catalyst for the synergistic treatment of CO and VOCs, its preparation method, and its application. The catalyst provided by this invention employs a dual-coating design. The inner coating (first coating) solves the problems of low purification efficiency, poor water resistance, and susceptibility to sulfur and chlorine poisoning in synergistic CO and VOCs catalysts. The outer coating (second coating) oxidizes low-valence sulfur compounds such as hydrogen sulfide, carbonyl sulfide, and carbon disulfide in flue gas into high-valence sulfur dioxide and rapidly desorbs them, while simultaneously protecting the inner coating and significantly extending the catalyst's lifespan.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a catalyst for the synergistic treatment of CO and VOCs, the catalyst comprising a matrix and a first coating and a second coating sequentially loaded on the matrix; The first coating comprises a first carrier, a first active component, an antisulfur agent, and a first binder. The first carrier comprises an MFI hierarchical porous molecular sieve, and the first active component comprises ruthenium and platinum. The second coating includes a second carrier, a second active component, and a second binder. The second carrier includes titanium dioxide, and the second active component includes chromium oxide and molybdenum oxide.

[0009] In this invention, the CO and VOCs synergistic treatment catalyst employs a dual-coating design. The inner coating uses a ruthenium-platinum dual-noble metal system as the active component to address the catalyst's susceptibility to chlorine poisoning. Simultaneously, it utilizes a molecular sieve with a multi-level porous structure (MFI) as a carrier to optimize the diffusion pathways of poisoning substances such as water, sulfur, and chlorine, enabling rapid desorption of these substances. Furthermore, it incorporates an anti-sulfur agent with excellent anti-sintering properties. The outer coating uses chromium and molybdenum as active components to resist and withstand sulfur, with titanium dioxide, rich in acidic sites, as a carrier. This allows for the oxidation of low-valence sulfur compounds such as hydrogen sulfide, carbonyl sulfide, and carbon disulfide in flue gas to high-valence sulfur dioxide, followed by rapid desorption, thus protecting the inner coating. Therefore, the CO and VOCs synergistic treatment catalyst provided by this invention exhibits high resistance and long lifespan.

[0010] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0011] Preferably, the matrix comprises honeycomb cordierite or mullite.

[0012] Preferably, the loading amount of the first coating on the substrate is 4wt.% to 6wt.%, for example, 4wt.%, 4.5wt.%, 5wt.%, 5.5wt.%, or 6wt.%.

[0013] Preferably, the loading amount of the second coating on the substrate is 2wt.% to 3wt.%, for example, 2wt.%, 2.2wt.%, 2.5wt.%, 2.7wt.% or 3wt.%.

[0014] Preferably, the MFI multi-level porous molecular sieve includes mesoporous channels and microporous channels.

[0015] Preferably, the diameter of the mesopores is 2nm to 10nm, such as 2nm, 5nm, 7nm, 9nm or 10nm, and the diameter of the micropores is 0.7nm to 2nm, such as 0.7nm, 1nm, 1.2nm, 1.5nm, 1.7nm or 2nm.

[0016] In this invention, MFI hierarchical porous molecular sieve is used as a carrier for precious metal active materials. Its special pore structure, which combines mesoporous and microporous structures, is conducive to the rapid desorption of poisoning substances such as water, sulfur, and chlorine, thereby mitigating catalyst poisoning and extending the catalyst's service life.

[0017] Preferably, the loading amount of the precious metal on the first carrier is 0.1wt.% to 3wt.%, for example, 0.1wt.%, 0.3wt.%, 0.5wt.%, 1wt.%, 1.5wt.%, 2wt.%, 2.5wt.% or 3wt.%.

[0018] Preferably, the mass ratio of ruthenium to platinum is 1:(0.3~0.6), for example, 1:0.3, 1:0.4, 1:0.5 or 1:0.6.

[0019] The inner coating of this invention uses ruthenium as the core and platinum as the auxiliary ruthenium-platinum dual noble metal system as the active component, which has better chlorine resistance. Under the premise of ensuring catalyst activity, it solves the problem of catalyst poisoning by chlorine. Ruthenium has better chlorine resistance in the catalytic process, while platinum has better oxidation performance. By controlling the mass ratio of ruthenium to platinum at 1:(0.3~0.6), the chlorine resistance of the catalyst can be improved while ensuring the oxidation capacity of the catalyst.

[0020] Preferably, the antisulfur agent comprises a cerium-zirconium solid solution.

[0021] In this invention, pure cerium oxide is prone to sintering at high temperatures, leading to a significant decrease in performance; while cerium-zirconium solid solution, due to its special cubic lattice structure, has high resistance to sintering, thereby improving the catalyst's sulfur resistance and extending its service life.

[0022] Preferably, the specific surface area of ​​the cerium-zirconium solid solution is 50 m². 2 / g~100m 2 / g, for example 50m 2 / g、60m 2 / g、70m 2 / g、80m 2 / g、90m 2 / g or 100m 2 / g etc.

[0023] Preferably, the antisulfur agent accounts for 3 wt.% to 15 wt.% of the mass of the first coating, such as 3 wt.%, 5 wt.%, 8 wt.%, 10 wt.%, 12 wt.%, or 15 wt.%.

[0024] Preferably, the first adhesive comprises a hydrophobic adhesive, more preferably SiO2.

[0025] Preferably, the first adhesive accounts for 8 wt.% to 30 wt.% of the mass of the first coating, such as 8 wt.%, 12 wt.%, 17 wt.%, 20 wt.%, 25 wt.%, or 30 wt.%.

[0026] Preferably, the loading amount of the second active component on the second carrier is 12 wt.% to 27 wt.%, for example, 12 wt.%, 15 wt.%, 19 wt.%, 23 wt.% or 27 wt.%.

[0027] Preferably, the mass ratio of chromium oxide to molybdenum oxide is (1.4~2):1, for example, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, etc.

[0028] Preferably, the second adhesive comprises a hydrophilic adhesive, more preferably Al2O3.

[0029] Preferably, the second adhesive accounts for 6.5 wt.% to 13 wt.% of the mass of the second coating, for example, 6.5 wt.%, 8 wt.%, 8.5 wt.%, 10 wt.%, 12 wt.%, 13 wt.%, etc.

[0030] In a second aspect, the present invention provides a method for preparing a CO and VOCs synergistic treatment catalyst as described in the first aspect, the preparation method comprising: S1. The first carrier suspension, the noble metal salt solution and the dispersant are mixed and subjected to a first ball milling. After a first calcination, a solid powder is obtained. Then, the solid powder, the dispersant, the antisulfur agent, the first binder precursor and the solvent are mixed and subjected to a second ball milling to obtain a first coating slurry. S2. Immerse the substrate in the first coating slurry of S1. After immersion, remove the substrate and calcine it again to obtain a substrate loaded with the first coating. S3. Titanium dioxide, chromium oxide, molybdenum oxide, dispersant, second binder precursor and solvent are mixed and then ball-milled in a third process to obtain the second coating slurry; S4. Immerse the substrate loaded with the first coating described in S2 into the second coating slurry described in S3. After the immersion is completed, remove the substrate and calcine it in a third calcination to obtain the CO and VOCs synergistic treatment catalyst.

[0031] Preferably, in the first carrier suspension in S1, the mass percentage of the first carrier is 15wt.% to 35wt.%, for example, 15wt.%, 20wt.%, 25wt.%, 30wt.%, or 35wt.%.

[0032] Preferably, the precious metal salt solution comprises a precious metal salt and a solvent, wherein the precious metal salt comprises a precious metal chloride or a precious metal nitrate.

[0033] Preferably, the mass concentration of the noble metal salt solution is 4 wt.% to 6 wt.%, for example, 4 wt.%, 4.5 wt.%, 5 wt.%, 5.5 wt.%, or 6 wt.%.

[0034] Preferably, the dispersant comprises any one or a combination of at least two of polyethylene glycol, sodium dodecylbenzenesulfonate, polyacrylamide, polyvinylpyrrolidone, or Tween 20.

[0035] Preferably, the first binder precursor in S1 comprises an acidic silica sol.

[0036] Preferably, the mass ratio of the solid powder, dispersant, antisulfur agent and first binder precursor in S1 is 1:(0.04~0.25):(0.15~0.6):(0.5~1), for example 1:0.04:0.15:0.5, 1:0.08:0.2:0.6, 1:0.1:0.2:0.7, 1:0.15:0.4:0.8, 1:0.2:0.5:0.9 or 1:0.25:0.6:1, etc.

[0037] Preferably, the rotational speeds of the first ball mill in S1, the second ball mill in S1, and the third ball mill in S3 are each independently 100 r / min to 400 r / min, for example, 100 r / min, 200 r / min, 300 r / min, or 400 r / min, and the time for each is independently 2 h to 6 h, for example, 2 h, 3 h, 4 h, 5 h, or 6 h.

[0038] Preferably, the first ball mill in S1, the second ball mill in S1, and the third ball mill in S3 are each independently ball milled until the average particle size of the product is ≤500nm, such as 100nm, 200nm, 300nm, 400nm, or 500nm.

[0039] Preferably, after the first ball milling is completed in S1, the product is dried in a rotary evaporator.

[0040] Preferably, the rotation speed of the rotary evaporator is 30 r / min to 120 r / min, for example, 30 r / min, 50 r / min, 70 r / min, 100 r / min or 120 r / min, and the temperature is 90℃ to 110℃, for example, 90℃, 95℃, 100℃, 105℃ or 110℃.

[0041] Preferably, the first calcination temperature in S1 is 400℃~600℃, such as 400℃, 450℃, 500℃, 550℃ or 600℃, and the time is 3h~8h, such as 3h, 4h, 5h, 6h, 7h or 8h.

[0042] Preferably, the synthesis method of the first carrier includes a layer-bulk hybridization method.

[0043] Preferably, the layered-bulk hybrid method includes: hydrothermal crystallization treatment of the precursor solution of the first carrier, followed by washing, filtration and first drying of the product to obtain the MFI hierarchical porous molecular sieve.

[0044] In this invention, the layered-bulk hybrid synthesis method makes it easier to control the pore diameter of the molecular sieve, and a suitable pore diameter is conducive to the rapid desorption of poisoned substances, slows down catalyst poisoning, and extends the service life of the catalyst.

[0045] Preferably, the temperature of the hydrothermal crystallization treatment is 60℃~90℃, such as 60℃, 70℃, 80℃ or 90℃, and the time is 20h~25h, such as 20h, 21h, 22h, 23h, 24h or 25h.

[0046] Preferably, the washing continues until the washing solution is neutral.

[0047] Preferably, the temperature of the first drying is 70℃~90℃, such as 70℃, 75℃, 80℃, 85℃ or 90℃.

[0048] Preferably, the antisulfur agent in S1 includes a cerium-zirconium solid solution, and the preparation method of the cerium-zirconium solid solution includes a co-precipitation hydrothermal reflux method.

[0049] Preferably, the co-precipitation hydrothermal reflux method includes: using cerium nitrate and zirconium nitrate as raw materials, and ammonia water as a precipitant, reacting at a pH of 10-11 to obtain a precipitate, and then filtering, washing and drying the precipitate in sequence, and calcining it at 450℃-550℃ for 3h-6h to obtain the cerium-zirconium solid solution.

[0050] Preferably, the substrate described in S2 is pretreated before use.

[0051] Preferably, the pretreatment includes: immersing the matrix in an oxalic acid solution, washing it, and then performing a second drying.

[0052] Preferably, the oxalic acid solution has a mass concentration of 30 wt.% to 70 wt.%, such as 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, or 70 wt.%.

[0053] Preferably, the soaking temperature is 70℃~90℃, such as 70℃, 75℃, 80℃, 85℃ or 90℃, and the soaking time is 2h~3h, such as 2h, 2.2h, 2.5h, 2.7h or 3h.

[0054] Preferably, the temperature of the second drying is 60°C to 120°C, such as 60°C, 80°C, 100°C or 120°C.

[0055] Preferably, the temperatures of the second roasting in S2 and the third roasting in S4 are each independently 400℃~500℃, such as 400℃, 420℃, 440℃, 460℃, 480℃ or 500℃, and the times are each independently 2h~6h, such as 2h, 3h, 4h, 5h or 6h.

[0056] Preferably, the second binder precursor in S3 comprises boehmite.

[0057] Preferably, the mass ratio of titanium dioxide, chromium oxide, molybdenum oxide, dispersant, and second binder precursor in S3 is 1:(0.1~0.25):(0.06~0.15):(0.03~0.2):(0.15~0.3), for example 1:0.1:0.06:0.03:0.15, 1:0.15:0.08:0.07:0.2, 1:0.2:0.1:0.1:0.25, or 1:0.25:0.15:0.2:0.3, etc.

[0058] Thirdly, the present invention also provides the application of the CO and VOCs synergistic treatment catalyst as described in the first aspect in flue gas treatment.

[0059] Compared with the prior art, the present invention has the following beneficial effects: The catalyst provided by this invention adopts a double-coating design. The inner coating solves the problems of low purification efficiency, poor water resistance, and easy sulfur and chlorine poisoning in the synergistic treatment of CO and VOCs. The outer coating can oxidize low-valence sulfur such as hydrogen sulfide, carbonyl sulfide, and carbon disulfide in flue gas into high-valence sulfur dioxide and desorb it quickly. At the same time, it protects the inner coating and greatly extends the service life of the catalyst. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0061] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0062] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0063] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0064] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0065] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0066] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0067] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0068] In this invention, "optional" means that something is optional, that is, it refers to either "with" or "without". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0069] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0070] The coating loading of the CO and VOCs synergistic treatment catalysts in the following embodiments is calculated as follows: Coating loading = Mass of surface coating layer / Mass of cordierite or mullite support × 100%.

[0071] Example 1 This embodiment provides a catalyst for the synergistic treatment of CO and VOCs, comprising a honeycomb cordierite matrix and a first coating (4.58 wt.%) and a second coating (2.25 wt.%) sequentially loaded onto the matrix. The first coating uses MFI hierarchical porous molecular sieve as the first support, ruthenium-platinum dual noble metals as the first active component (1.1 wt.% loaded on the first support, with a ruthenium to platinum mass ratio of 1:0.47), cerium-zirconium solid solution as an antisulfur agent (8.9 wt.% of the first coating), and SiO2 as the first binder. The second coating uses titanium dioxide as the support, chromium oxide and molybdenum oxide as the second active components (13.7 wt.% and 6.85 wt.% loaded on the second support, respectively), and Al2O3 as the second binder. The preparation method is as follows: (1) The honeycomb cordierite carrier was immersed in an oxalic acid solution with a temperature of 80℃ and a mass concentration of 60wt.% for 2 hours. After taking it out, the oxalic acid solution was rinsed off with deionized water and dried at 80℃ to obtain the matrix.

[0072] (2) MFI hierarchical porous molecular sieves were synthesized by layer-bulk hybridization. The silicon source (tetraethyl orthosilicate), aluminum source (aluminum nitrate), dual template agent (Bola type surfactant and tetraalkylammonium hydroxide) and water were mixed and hydrothermally crystallized at 80°C for 24 hours. After rinsing with deionized water until neutral, the mixture was filtered and dried at 80°C.

[0073] (3) Mix 500g of MFI multi-level porous molecular sieve and 2L of deionized water to prepare a suspension A with a mass concentration of 20%; mix 35g of platinum nitrate solution with a mass concentration of 5% and 75g of ruthenium nitrate solution with a mass concentration of 5% to prepare a precious metal mixed solution B; add precious metal mixed solution B and 20g of polyethylene glycol to suspension A and mix evenly, then put it into a ball mill and ball mill for 3h, with the speed controlled at 200r / min, until the particle size is less than 500nm; put the ball-milled suspension into a rotary evaporator, with the drying temperature of the rotary evaporator controlled at 100℃ and the speed controlled at 60r / min, until the material is dried; finally, transfer the material to a muffle furnace and calcine at 550℃ for 4h to obtain solid powder.

[0074] (4) Cerium-zirconium solid solution was prepared by co-precipitation hydrothermal reflux method. Cerium nitrate and zirconium nitrate were used as raw materials, ammonia water was used as precipitant, the pH value was controlled at 10, and the precipitate was obtained after aging for 24 hours. The precipitate was filtered, washed and dried, and then calcined at 500℃ for 4 hours to obtain cerium-zirconium solid solution.

[0075] (5) Add 200g of acidic silica sol (silica content 30wt.%), 15g of polyacrylamide, 15g of Tween 20, 45g of cerium zirconium solid solution and 400g of catalyst active powder to 2L of deionized water and mix evenly. Then put it into a ball mill and ball mill for 4 hours, with the speed controlled at 250r / min, until the particle size is less than 500nm to obtain the first coating slurry.

[0076] (6) Immerse the pretreated substrate in the first coating slurry, remove it and blow out the slurry in the pores, and then bake it at 450°C for 4 hours to obtain the substrate loaded with the first coating.

[0077] (7) Add 40g of boehmite (alumina content 80wt.%), 40g of chromium oxide, 20g of molybdenum oxide, 10g of Tween 20 and 200g of titanium dioxide to 2L of deionized water and mix evenly. Then put it into a ball mill and ball mill for 3h, with the speed controlled at 250r / min, until the particle size is less than 500nm to obtain the second coating slurry.

[0078] (8) Immerse the substrate loaded with the first coating into the second coating slurry, remove it and blow out the slurry in the pores, and then calcine it at 450°C for 4 hours to obtain the CO and VOCs synergistic treatment catalyst.

[0079] Example 2 This embodiment provides a catalyst for the synergistic treatment of CO and VOCs, comprising a honeycomb cordierite matrix and a first coating (5.26 wt.%) and a second coating (2.36 wt.%) sequentially loaded onto the matrix. The first coating uses MFI hierarchical porous molecular sieve as the first support, ruthenium-platinum dual noble metals as the first active component (0.83 wt.% loaded on the first support, with a ruthenium to platinum mass ratio of 1:0.33), cerium-zirconium solid solution as an antisulfur agent (6.9 wt.% by mass in the first coating), and SiO2 as the first binder. The second coating uses titanium dioxide as the support, chromium oxide and molybdenum oxide as the second active components (12.0 wt.% and 8.6 wt.% loaded on the second support, respectively), and Al2O3 as the second binder. The preparation method is as follows: (1) The honeycomb cordierite carrier was immersed in an oxalic acid solution with a mass concentration of 60% at 80℃ for 2 hours. After taking it out, the oxalic acid solution was rinsed off with deionized water and dried at 80℃ to obtain the matrix.

[0080] (2) MFI hierarchical porous molecular sieves were synthesized by layer-bulk hybridization. The silicon source (tetraethyl orthosilicate), aluminum source (aluminum nitrate), dual template agent (Bola type surfactant and tetraalkylammonium hydroxide) and water were mixed and hydrothermally crystallized at 80°C for 24 hours. After rinsing with deionized water until neutral, the mixture was filtered and dried at 80°C.

[0081] (3) Mix 500g of MFI multi-level porous molecular sieve and 2L of deionized water to prepare a suspension A with a mass concentration of 20%; mix 24g of platinum chloride solution with a mass concentration of 5% and 72g of ruthenium chloride solution with a mass concentration of 5% to prepare a precious metal mixed solution B; add the precious metal mixed solution B and 20g of sodium dodecylbenzenesulfonate to suspension A and mix evenly, then put it into a ball mill and ball mill for 3h at a speed of 200r / min until the particle size is less than 500nm; put the ball-milled suspension into a rotary evaporator and dry it at a temperature of 100℃ and a speed of 60r / min until the material is dry; finally, transfer the material to a muffle furnace and calcine it at 550℃ for 4h to obtain a solid powder.

[0082] (4) Cerium-zirconium solid solution was prepared by co-precipitation hydrothermal reflux method. Cerium nitrate and zirconium nitrate were used as raw materials, ammonia water was used as precipitant, the pH value was controlled at 10.5, and the precipitate was obtained after aging for 24 hours. The precipitate was filtered, washed and dried, and then calcined at 500℃ for 4 hours to obtain cerium-zirconium solid solution.

[0083] (5) Add 200g of acidic silica sol (silica content 30wt.%), 15g of polyacrylamide, 15g of Tween 20, 40g of cerium zirconium solid solution and 480g of catalyst active powder to 2L of deionized water and mix evenly. Then put it into a ball mill and ball mill for 4 hours, controlling the speed at 250r / min, until the particle size is less than 500nm to obtain the first coating slurry.

[0084] (6) Immerse the pretreated substrate in the first coating slurry, remove it and blow out the slurry in the pores, and then bake it at 450°C for 4 hours to obtain a substrate loaded with the first coating.

[0085] (7) Add 40g of boehmite (alumina content 80wt.%), 35g of chromium oxide, 25g of molybdenum oxide, 10g of Tween 20 and 200g of titanium dioxide to 2L of deionized water and mix evenly. Then put the mixture into a ball mill and ball mill for 3 hours at a speed of 250r / min until the particle size is less than 500nm to obtain the second coating slurry.

[0086] (8) Immerse the substrate loaded with the first coating into the second coating slurry, remove it and blow out the slurry in the pores, and then calcine it at 450°C for 4 hours to obtain the CO and VOCs synergistic treatment catalyst.

[0087] Example 3 This embodiment provides a catalyst for the synergistic treatment of CO and VOCs, comprising a honeycomb cordierite matrix and a first coating (5.65 wt.%) and a second coating (2.59 wt.%) sequentially loaded onto the matrix. The first coating uses MFI hierarchical porous molecular sieve as the first support, ruthenium-platinum dual noble metals as the first active component (0.73 wt.% loaded on the first support, with a ruthenium to platinum mass ratio of 1:0.5), cerium-zirconium solid solution as an antisulfur agent (7.6 wt.% by mass in the first coating), and SiO2 as the first binder. The second coating uses titanium dioxide as the support, chromium oxide and molybdenum oxide as the second active components (chromium oxide and molybdenum oxide loaded on the second support at 15.7 wt.% and 8.5 wt.%, respectively), and Al2O3 as the second binder. The preparation method is as follows: (1) The honeycomb cordierite carrier was immersed in an oxalic acid solution with a mass concentration of 60% at 80℃ for 2 hours. After taking it out, the oxalic acid solution was rinsed off with deionized water and dried at 80℃ to obtain the matrix.

[0088] (2) MFI hierarchical porous molecular sieves were synthesized by layer-bulk hybridization. The silicon source (tetraethyl orthosilicate), aluminum source (aluminum nitrate), dual template agent (Bola type surfactant and tetraalkylammonium hydroxide) and water were mixed and hydrothermally crystallized at 80°C for 24 hours. After rinsing with deionized water until neutral, the mixture was filtered and dried at 80°C.

[0089] (3) Mix 500g of MFI multi-level porous molecular sieve and 2L of deionized water to prepare a suspension A with a mass concentration of 20%; mix 30g of platinum nitrate solution with a mass concentration of 5% and 60g of ruthenium nitrate solution with a mass concentration of 5% to prepare a precious metal mixture B; add the precious metal mixture B and 20g of polyethylene glycol to suspension A and mix evenly, then put it into a ball mill and ball mill for 3h at a speed of 200r / min until the particle size is less than 500nm; put the ball-milled suspension into a rotary evaporator and dry it at a temperature of 100℃ and a speed of 60r / min until the material is dry; finally, transfer the material to a muffle furnace and calcine it at 550℃ for 4h to obtain a solid powder.

[0090] (4) Cerium-zirconium solid solution was prepared by co-precipitation hydrothermal reflux method. Cerium nitrate and zirconium nitrate were used as raw materials, ammonia water was used as precipitant, the pH value was controlled at 11, and the precipitate was obtained after aging for 24 hours. The precipitate was filtered, washed and dried, and then calcined at 500℃ for 4 hours to obtain cerium-zirconium solid solution.

[0091] (5) Add 200g of acidic silica sol (silica content 30wt.%), 15g of polyacrylamide, 15g of Tween 20, 42g of cerium zirconium solid solution and 450g of catalyst active powder to 2L of deionized water and mix evenly. Then put it into a ball mill and ball mill for 4 hours, with the speed controlled at 250r / min. Ball mill until the particle size is less than 500nm to obtain the first coating slurry.

[0092] (6) Immerse the pretreated substrate in the first coating slurry, remove it and blow out the slurry in the pores, and then bake it at 450°C for 4 hours to obtain a substrate loaded with the first coating.

[0093] (7) Add 40g of boehmite (alumina content 80wt.%), 48g of chromium oxide, 26g of molybdenum oxide, 10g of Tween 20 and 200g of titanium dioxide to 2L of deionized water and mix evenly. Then put the mixture into a ball mill and ball mill for 3 hours at a speed of 250r / min until the particle size is less than 500nm to obtain the second coating slurry.

[0094] (8) Immerse the substrate loaded with the first coating into the second coating slurry, remove it and blow out the slurry in the pores, and then calcine it at 450°C for 4 hours to obtain the CO and VOCs synergistic treatment catalyst.

[0095] Example 4 This embodiment provides a catalyst for the synergistic treatment of CO and VOCs, comprising a honeycomb cordierite matrix and a first coating (4 wt.% loading) and a second coating (2 wt.% loading) sequentially loaded on the matrix. The first coating uses MFI hierarchical porous molecular sieve as the first support, ruthenium-platinum dual noble metals as the first active component (0.1 wt.% loading on the first support, with a ruthenium to platinum mass ratio of 1:0.3), cerium-zirconium solid solution as an antisulfur agent (3 wt.% mass percentage in the first coating), and SiO2 as the first binder. The second coating uses titanium dioxide as the support, chromium oxide and molybdenum oxide as the second active components (7 wt.% and 5 wt.% loading on the second support, respectively), and Al2O3 as the second binder. The preparation method is as follows: (1) The honeycomb cordierite carrier was immersed in an oxalic acid solution with a mass concentration of 30% at a temperature of 70℃ for 3 hours. After taking it out, the oxalic acid solution was rinsed off with deionized water and dried at 60℃ to obtain the matrix.

[0096] (2) MFI hierarchical porous molecular sieves were synthesized by layer-bulk hybridization. The silicon source (tetraethyl orthosilicate), aluminum source (aluminum nitrate), dual template agent (Bola type surfactant and tetraalkylammonium hydroxide) and water were mixed and hydrothermally crystallized at 60°C for 25 hours. After rinsing with deionized water until neutral, the mixture was filtered and dried at 70°C.

[0097] (3) Mix 500g of MFI multi-level porous molecular sieve and 2.8L of deionized water to prepare a suspension A with a mass concentration of 15%; mix 3.3g of platinum nitrate solution with a mass concentration of 4% and 11g of ruthenium nitrate solution with a mass concentration of 4% to prepare a precious metal mixed solution B; add precious metal mixed solution B and 20g of polyethylene glycol to suspension A and mix evenly, then put it into a ball mill and ball mill for 2 hours at a speed of 400r / min until the particle size is less than 500nm; put the ball-milled suspension into a rotary evaporator and dry it at a temperature of 90℃ and a speed of 120r / min until the material is dry; finally, transfer the material to a muffle furnace and calcine it at 400℃ for 8 hours to obtain a solid powder.

[0098] (4) Cerium-zirconium solid solution was prepared by co-precipitation hydrothermal reflux method. Cerium nitrate and zirconium nitrate were used as raw materials, ammonia water was used as precipitant, the pH value was controlled at 10, and the precipitate was obtained after aging for 24 hours. The precipitate was filtered, washed and dried, and then calcined at 500℃ for 4 hours to obtain cerium-zirconium solid solution.

[0099] (5) Add 110g of acidic silica sol (silica content 30wt.%), 13g of polyacrylamide, 13g of Tween 20, 12.5g of cerium zirconium solid solution and 365g of catalyst active powder to 2L of deionized water and mix evenly. Then put it into a ball mill and ball mill for 2 hours at a speed of 400r / min until the particle size is less than 500nm to obtain the first coating slurry.

[0100] (6) Immerse the pretreated substrate in the first coating slurry, remove it and blow out the slurry in the pores, and then bake it at 400°C for 8 hours to obtain the substrate loaded with the first coating.

[0101] (7) Add 32.5g of boehmite (alumina content 80wt.%), 28g of chromium oxide, 20g of molybdenum oxide, 11g of Tween 20 and 326g of titanium dioxide to 2L of deionized water and mix evenly. Then put the mixture into a ball mill and ball mill for 2 hours at a speed of 400r / min until the particle size is less than 500nm to obtain the second coating slurry.

[0102] (8) Immerse the substrate loaded with the first coating into the second coating slurry, remove it and blow out the slurry in the pores, and then calcine it at 400°C for 8 hours to obtain the CO and VOCs synergistic treatment catalyst.

[0103] Example 5 This embodiment provides a catalyst for the synergistic treatment of CO and VOCs, comprising a honeycomb cordierite matrix and a first coating (6 wt.% loading) and a second coating (3 wt.% loading) sequentially loaded on the matrix. The first coating uses MFI hierarchical porous molecular sieve as the first support, ruthenium-platinum dual noble metals as the first active component (3 wt.% loading on the first support, ruthenium to platinum mass ratio 1:0.6), cerium-zirconium solid solution as an antisulfur agent (15 wt.% mass percentage in the first coating), and SiO2 as the first binder. The second coating uses titanium dioxide as the support, chromium oxide and molybdenum oxide as the second active components (chromium oxide and molybdenum oxide loadings of 18 wt.% and 9 wt.% respectively on the second support), and Al2O3 as the second binder. The preparation method is as follows: (1) The honeycomb cordierite carrier was immersed in an oxalic acid solution with a temperature of 90℃ and a mass concentration of 70% for 2.5h. After taking it out, the oxalic acid solution was rinsed off with deionized water and dried at 120℃ to obtain the matrix.

[0104] (2) MFI hierarchical porous molecular sieves were synthesized by layer-bulk hybridization. The silicon source (tetraethyl orthosilicate), aluminum source (aluminum nitrate), dual template agent (Bola type surfactant and tetraalkylammonium hydroxide) and water were mixed and hydrothermally crystallized at 90°C for 20 hours. After rinsing with deionized water until neutral, the mixture was filtered and dried at 90°C.

[0105] (3) Mix 500g of MFI multi-level porous molecular sieve and 0.92L of deionized water to prepare a suspension A with a mass concentration of 35%; mix 56g of platinum nitrate solution with a mass concentration of 6% and 94g of ruthenium nitrate solution with a mass concentration of 6% to prepare a precious metal mixed solution B; add the precious metal mixed solution B and 20g of polyethylene glycol to suspension A and mix evenly, then put it into a ball mill and ball mill for 6h at a speed of 100r / min until the particle size is less than 500nm; put the ball-milled suspension into a rotary evaporator and dry it at a temperature of 110℃ and a speed of 30r / min until the material is dry; finally, transfer the material to a muffle furnace and calcine it at 600℃ for 3h to obtain a solid powder.

[0106] (4) Cerium-zirconium solid solution was prepared by co-precipitation hydrothermal reflux method. Cerium nitrate and zirconium nitrate were used as raw materials, ammonia water was used as precipitant, the pH value was controlled at 10, and the precipitate was obtained after aging for 24 hours. The precipitate was filtered, washed and dried, and then calcined at 500℃ for 4 hours to obtain cerium-zirconium solid solution.

[0107] (5) Add 300g of acidic silica sol (silica content 30wt.%), 20g of polyacrylamide, 20g of Tween 20, 45g of cerium zirconium solid solution and 165g of catalyst active powder to 2L of deionized water and mix evenly. Then put it into a ball mill and ball mill for 6 hours. The speed is controlled at 100r / min. Ball mill until the particle size is less than 500nm to obtain the first coating slurry.

[0108] (6) Immerse the pretreated substrate in the first coating slurry, remove it and blow out the slurry in the pores, and then bake it at 600°C for 3 hours to obtain the substrate loaded with the first coating.

[0109] (7) Add 65g of boehmite (alumina content 80wt.%), 72g of chromium oxide, 36g of molybdenum oxide, 13g of Tween 20 and 240g of titanium dioxide to 2L of deionized water and mix evenly. Then put the mixture into a ball mill and ball mill for 6 hours at a speed of 100r / min until the particle size is less than 500nm to obtain the second coating slurry.

[0110] (8) Immerse the substrate loaded with the first coating into the second coating slurry, remove it and blow out the slurry in the pores, and then calcine it at 600°C for 3 hours to obtain the CO and VOCs synergistic treatment catalyst.

[0111] Example 6 The difference between this embodiment and embodiment 3 is that the antisulfur agent is cerium oxide; step (4) is omitted in the preparation process, and the cerium-zirconium solid solution in step (5) is replaced with cerium oxide; The remaining preparation methods and parameters are consistent with those in Example 1.

[0112] Example 7 The difference between this embodiment and Embodiment 1 is that the first binder, acidic silica sol, is replaced with an equal amount of effective material in the second binder, boehmite; in step (5) of the preparation process, 200g of acidic silica sol is replaced with 75g of boehmite. The remaining preparation methods and parameters are consistent with those in Example 1.

[0113] Example 8 The difference between this embodiment and Embodiment 1 is that the second binder, boehmite, is replaced with an equal amount of the first binder, acidic silica sol; in step (7) of the preparation process, 40g of boehmite is replaced with 106.7g of acidic silica sol. The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Example 9 The difference between this embodiment and embodiment 1 is that the mass ratio of ruthenium to platinum is 1:1; in step (3) of the preparation process, 55g of platinum nitrate solution with a mass concentration of 5% and 55g of ruthenium nitrate solution with a mass concentration of 5% are mixed to prepare a noble metal mixture B. The remaining preparation methods and parameters are consistent with those in Example 1.

[0115] Comparative Example 1 The difference between this comparative example and Example 1 is that the CO and VOCs synergistic treatment catalyst does not contain a second coating; steps (7) and (8) are omitted in the preparation process. The remaining preparation methods and parameters are consistent with those in Example 1.

[0116] Comparative Example 2 The difference between this comparative example and Example 2 is that the first active component is a palladium-platinum dual noble metal; and ruthenium chloride in step (3) is replaced with palladium chloride during the preparation process. The remaining preparation methods and parameters are consistent with those in Example 2.

[0117] Comparative Example 3 The difference between this comparative example and Example 1 is that the first carrier is a β molecular sieve; step (2) is not performed in the preparation process, and the MFI hierarchical porous molecular sieve is replaced with a β molecular sieve in step (3); The remaining preparation methods and parameters are consistent with those in Example 1.

[0118] Comparative Example 4 The difference between this comparative example and Example 1 is that the second support is also an MFI hierarchical porous molecular sieve; in step (7) of the preparation process, titanium dioxide is replaced with an MFI hierarchical porous molecular sieve. The remaining preparation methods and parameters are consistent with those in Example 1.

[0119] Comparative Example 5 The difference between this comparative example and Example 1 is that the second active component does not contain molybdenum oxide; and molybdenum oxide is not added in step (7) of the preparation process. The remaining preparation methods and parameters are consistent with those in Example 1.

[0120] Performance testing Example 1 and Comparative Example 1: At a temperature of 240°C and a space velocity of 15000 h⁻¹ -1 The flue gas moisture content is 15%, and the sulfur dioxide concentration is 50 mg / m³. 3 The hydrogen sulfide concentration is 150 mg / m³. 3 The carbonyl sulfide concentration is 150 mg / m³. 3 The carbon disulfide concentration was 150 mg / m³. 3 Under the same conditions, the catalysts prepared in Example 1 and Comparative Example 1 were subjected to long-term stability evaluation, and the test results are shown in Table 1.

[0121] Example 2 and Comparative Example 2: At a temperature of 240°C and a space velocity of 15000 h⁻¹ -1 The flue gas moisture content is 15%, and the sulfur dioxide concentration is 35 mg / m³. 3 The hydrogen chloride concentration is 300 mg / m³. 3 Under the same conditions, the catalysts prepared in Example 2 and Comparative Example 2 were subjected to long-term stability evaluation, and the test results are shown in Table 1.

[0122] Examples 3 and 6: At a temperature of 240°C and a space velocity of 15000 h⁻¹ -1 The flue gas moisture content is 10%, and the sulfur dioxide concentration is 35 mg / m³. 3 The hydrogen sulfide concentration is 100 mg / m³. 3 The carbonyl sulfide concentration is 100 mg / m³. 3 The carbon disulfide concentration is 100 mg / m³. 3 The hydrogen chloride concentration is 50 mg / m³. 3 Under the same conditions, the catalysts prepared in Example 3 and Example 6 were subjected to long-term stability evaluation, and the test results are shown in Table 1.

[0123] Examples 4 and 5: At a temperature of 240°C and a space velocity of 15000 h⁻¹ -1 The flue gas moisture content is 15%, and the sulfur dioxide concentration is 35 mg / m³. 3The hydrogen sulfide concentration is 100 mg / m³. 3 The carbonyl sulfide concentration is 100 mg / m³. 3 The carbon disulfide concentration is 100 mg / m³. 3 The hydrogen chloride concentration is 50 mg / m³. 3 Under the same conditions, the catalysts prepared in Examples 4 and 5 were subjected to long-term stability evaluation, and the test results are shown in Table 1.

[0124] Examples 1, 7, and 8: At a temperature of 240°C and a space velocity of 15000 h⁻¹ -1 The flue gas moisture content was 20%, and the sulfur dioxide concentration was 35 mg / m³. 3 The hydrogen chloride concentration is 25 mg / m³. 3 Under the same conditions, the catalysts prepared in Examples 1, 7 and 8 were subjected to long-term stability evaluation, and the test results are shown in Table 2.

[0125] Examples 1, 9 and Comparative Examples 3-5: at a temperature of 240°C and a space velocity of 15000 h⁻¹ -1 The flue gas moisture content is 15%, and the sulfur dioxide concentration is 35 mg / m³. 3 The hydrogen sulfide concentration is 100 mg / m³. 3 The carbonyl sulfide concentration is 100 mg / m³. 3 The carbon disulfide concentration is 100 mg / m³. 3 The hydrogen chloride concentration is 300 mg / m³. 3 Under the same conditions, the catalysts prepared in Examples 1, 9 and Comparative Examples 3-5 were subjected to long-term stability evaluation, and the test results are shown in Table 3.

[0126] It should be noted that in Tables 1 and 2, the data before " / " represents carbon monoxide efficiency, and the data after " / " represents VOCs efficiency.

[0127] Table 1 Table 2 Table 3 As shown in Tables 1-3, the CO and VOCs synergistic treatment catalyst provided by this invention can achieve good purification effect for the synergistic treatment of CO and VOCs in industrial flue gas.

[0128] As can be seen from the comparison of the data of Example 1 and Comparative Example 1 in Table 1, the first coating and the second coating of the present invention work synergistically. The catalyst second coating can serve as a protective layer against low-valence sulfur under the same flue gas conditions (hydrogen sulfide concentration 150 mg / m³).3 Carbonyl sulfide concentration 150 mg / m³ 3 Carbon disulfide concentration 150 mg / m³ 3 This method can achieve better flue gas purification effect. The catalyst deactivation rate of carbon monoxide is reduced from 8.17% / 1000h to 1.29% / 1000h ([deactivation rate per 1000h = 0h purification efficiency - 4000h purification efficiency] / 4, the same below), and VOCs are reduced from 13.86% / 1000h to 1.35% / 1000h. Furthermore, adding a second coating to the substrate can reduce the catalyst reaction temperature by 60℃.

[0129] As can be seen from the comparison of the data of Example 2 and Comparative Example 2 in Table 1, the inner coating, with the ruthenium-platinum dual noble metal system as the active component, reduced the catalyst deactivation rate of carbon monoxide from 11.00% / 1000h to 1.78% / 1000h and VOCs from 11.70% / 1000h to 1.91% / 1000h compared to ordinary platinum-palladium catalysts, and the chlorine tolerance concentration decreased from 25 mg / m³. 3 Increase to 300 mg / m 3 Furthermore, as can be seen from the comparison of data from Example 1 and Example 9 in Table 3, the present invention controls the mass ratio of ruthenium to platinum at 1:(0.3~0.6), which can better balance the activity and stability of the catalyst.

[0130] As can be seen from the comparison of the data of Example 3 and Example 6 in Table 1, the use of cerium-zirconium solid solution as a sulfur sacrificial agent in the inner coating of the catalyst can extend the service life of the catalyst compared with the use of cerium oxide. Using cerium-zirconium solid solution as an anti-sulfur agent can make the catalyst stable and non-sintering at 700°C for a long time, and can withstand short-term impact (4 hours) at 900°C, which can ensure the anti-sulfur ability of the catalyst in high-temperature operating environment and extend the service life of the catalyst.

[0131] Furthermore, a comparison of the data from Examples 1 and 7-8 in Table 2 shows that in this invention, the first coating uses a hydrophobic binder, acidic silica sol, which can effectively resist the influence of water in the flue gas on the activity and stability of the precious metal active substances in the first coating. The second coating uses a hydrophilic binder, pseudoboehmite, which can effectively filter water in the flue gas from entering the first coating through the second coating. The synergistic effect of the two coatings can achieve better results.

[0132] A comparison of the data from Example 1 and Comparative Examples 3-5 in Table 3 shows that the MFI hierarchical porous molecular sieve used as the carrier for the noble metal active material in the inner coating of the catalyst has a unique pore structure that optimizes the diffusion path of poisoning substances such as water, sulfur, and chlorine, thus mitigating catalyst poisoning and extending the catalyst's lifespan by more than 50%. In contrast, titanium dioxide is more suitable as the carrier for the outer coating. As shown in Table 3, molybdenum oxide and chromium oxide in the outer coating work synergistically; both must be present simultaneously to achieve better results.

[0133] As can be seen from the data comparison between Example 1 and Example 9 in Table 3, the inner coating is based on ruthenium, which has better chlorine resistance, and platinum is used as an auxiliary. The mass ratio of ruthenium to platinum is controlled within the preferred range of the present invention, which can solve the problem of easy chlorine poisoning of the catalyst while ensuring the catalyst activity and ensuring the service life of the catalyst.

[0134] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A catalyst for the synergistic treatment of CO and VOCs, characterized in that, The catalyst comprises a matrix and a first coating and a second coating sequentially loaded on the matrix; The first coating comprises a first carrier, a first active component, an antisulfur agent, and a first binder. The first carrier comprises an MFI hierarchical porous molecular sieve, and the first active component comprises ruthenium and platinum. The second coating includes a second carrier, a second active component, and a second binder. The second carrier includes titanium dioxide, and the second active component includes chromium oxide and molybdenum oxide.

2. The catalyst for synergistic treatment of CO and VOCs according to claim 1, characterized in that, The matrix comprises honeycomb cordierite or mullite; Preferably, the loading amount of the first coating on the substrate is 4 wt.% to 6 wt.%; Preferably, the loading amount of the second coating on the substrate is 2wt.% to 3wt.%.

3. The CO and VOCs synergistic treatment catalyst according to claim 1 or 2, characterized in that, The MFI multi-level porous molecular sieve includes mesoporous channels and microporous channels; Preferably, the diameter of the mesoporous channels is 2nm~10nm, and the diameter of the microporous channels is 0.7nm~2nm; Preferably, the loading amount of the first active component on the first support is 0.1 wt.%-3 wt.%; Preferably, the mass ratio of ruthenium to platinum is 1:(0.3~0.6); Preferably, the antisulfur agent comprises a cerium-zirconium solid solution; Preferably, the specific surface area of ​​the cerium-zirconium solid solution is 50 m². 2 / g~100m 2 / g; Preferably, the antisulfur agent accounts for 3 wt.% to 15 wt.% of the mass of the first coating; Preferably, the first adhesive comprises a hydrophobic adhesive, more preferably SiO2; Preferably, the first adhesive accounts for 8 wt.% to 30 wt.% of the mass of the first coating.

4. The CO and VOCs synergistic treatment catalyst according to any one of claims 1-3, characterized in that, The loading amount of the second active component on the second support is 12 wt.%~27 wt.%; Preferably, the mass ratio of chromium oxide to molybdenum oxide is (1.4~2):1; Preferably, the second adhesive comprises a hydrophilic adhesive, more preferably Al2O3; Preferably, the second adhesive accounts for 6.5 wt.% to 13 wt.% of the mass of the second coating.

5. A method for preparing a catalyst for the synergistic treatment of CO and VOCs as described in any one of claims 1-4, characterized in that, The preparation method includes: S1. The first carrier suspension, the noble metal salt solution and the dispersant are mixed and subjected to a first ball milling. After a first calcination, a solid powder is obtained. Then, the solid powder, the dispersant, the antisulfur agent, the first binder precursor and the solvent are mixed and subjected to a second ball milling to obtain a first coating slurry. S2. Immerse the substrate in the first coating slurry of S1. After immersion, remove the substrate and calcine it again to obtain a substrate loaded with the first coating. S3. Titanium dioxide, chromium oxide, molybdenum oxide, dispersant, second binder precursor and solvent are mixed and then ball-milled in a third process to obtain the second coating slurry; S4. Immerse the substrate loaded with the first coating described in S2 into the second coating slurry described in S3. After the immersion is completed, remove the substrate and calcine it in a third calcination to obtain the CO and VOCs synergistic treatment catalyst.

6. The preparation method according to claim 5, characterized in that, S1 In the first carrier suspension, the mass percentage of the first carrier is 15 wt.%~35 wt.%; Preferably, the mass concentration of the noble metal salt solution in S1 is 4 wt.%~6 wt.%; Preferably, the dispersant in S1 comprises any one or a combination of at least two of polyethylene glycol, sodium dodecylbenzenesulfonate, polyacrylamide, polyvinylpyrrolidone, or Tween 20; Preferably, the first adhesive precursor in step S1 comprises an acidic silica sol; Preferably, the mass ratio of the solid powder, dispersant, antisulfur agent and first binder precursor in S1 is 1:(0.04~0.25):(0.15~0.6):(0.5~1); Preferably, the rotational speeds of the first ball mill in S1, the second ball mill in S1, and the third ball mill in S3 are each independently 100 r / min to 400 r / min, and the time for each is independently 2 h to 6 h; Preferably, the first ball mill in S1, the second ball mill in S1, and the third ball mill in S3 are each independently ball milled until the average particle size of the product is ≤500nm.

7. The preparation method according to claim 5 or 6, characterized in that, S1 After the first ball milling is completed, the product is placed in a rotary evaporator to dry; Preferably, the rotary evaporator has a rotation speed of 30 r / min to 120 r / min and a temperature of 90℃ to 110℃; Preferably, the first calcination temperature in S1 is 400℃~600℃, and the time is 3h~8h.

8. The preparation method according to claim 6 or 7, characterized in that, The synthesis method of the first carrier includes a layered-bulk hybridization method; Preferably, the layered-bulk hybrid method includes: hydrothermal crystallization treatment of the precursor solution of the first support, followed by washing, filtration and first drying of the product to obtain the MFI hierarchical porous molecular sieve; Preferably, the hydrothermal crystallization treatment is performed at a temperature of 60°C to 90°C for a time of 20 to 25 hours. Preferably, the washing continues until the washing solution is neutral; Preferably, the temperature of the first drying is 70°C to 90°C.

9. The preparation method according to any one of claims 5-8, characterized in that, The substrate described in S2 is pretreated before use; Preferably, the pretreatment includes: immersing the matrix in an oxalic acid solution, washing it, and then performing a second drying; Preferably, the oxalic acid solution has a mass concentration of 30 wt.% to 70 wt.%. Preferably, the soaking temperature is 70℃~90℃, and the soaking time is 2h~3h; Preferably, the temperature for the second drying is 60°C to 120°C; Preferably, the temperatures of the second calcination in S2 and the third calcination in S4 are each independently 400℃~500℃, and the times are each independently 2h~6h; Preferably, the second binder precursor in step S3 comprises boehmite; Preferably, the mass ratio of titanium dioxide, chromium oxide, molybdenum oxide, dispersant, and second binder precursor in S3 is 1:(0.1~0.25):(0.06~0.15):(0.03~0.2):(0.15~0.3).

10. The application of a CO and VOCs synergistic treatment catalyst as described in any one of claims 1-4 in flue gas treatment.

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