A filter material layered catalyst for catalytic oxidation of flue gas CO and a preparation method and application thereof

Abstract

This invention discloses a layered filter media catalyst for the catalytic oxidation of CO in flue gas and its preparation method, belonging to the field of catalyst technology. The layered filter media catalyst comprises, from the inside out, a cordierite support layer, a Pt-W / TiO2 active catalyst layer, and a molecular sieve filter media protective layer. The Pt-W / TiO2 active catalyst layer is supported on the surface of the cordierite support layer; the molecular sieve filter media protective layer coats the surface of the Pt-W / TiO2 active catalyst layer. This invention fundamentally solves the problem of catalyst deactivation under complex pollutant environments after desulfurization, achieving efficient CO removal and long-term stable catalyst operation, providing a low-cost, high-reliability technical solution for the deep treatment of sintering flue gas.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a filter media layered catalyst for the catalytic oxidation of CO in flue gas, its preparation method and application. Background Technology

[0002] The sintering process in the steel industry is one of the main sources of air pollutant emissions. Its flue gas has a complex composition and contains high concentrations of CO (typically 5000-10000 mg / m³). 3 SO2, NO x And particulate matter (including heavy metals). With increasingly stringent environmental standards, sintering flue gas needs to undergo multiple processes such as desulfurization and denitrification. Among these, CO catalytic oxidation is a key link in synergistic emission reduction, which can effectively reduce carbon emissions and recover heat energy. However, existing CO catalysts face severe challenges in practical applications: since the desulfurization process is usually placed before CO catalytic oxidation (or in some processes the catalyst is placed after desulfurization), residual particulate matter in the flue gas (such as desulfurization byproducts and heavy metal compounds) is prone to deposit on the catalyst surface, forming physical coverage or chemical poisoning, leading to deactivation of active sites, a significant reduction in catalyst life (usually less than 6 months), high replacement frequency, and a significant increase in operating costs.

[0003] Currently, research on catalytic oxidation catalysts for CO in sintering flue gas mainly focuses on two aspects: optimization of active components and modification of the support. For example, patent CN120515490A discloses a molecular sieve-coated noble metal-rare earth metal / TiO2 monolithic catalyst, which blocks sulfur species and heavy metal poisoning through the molecular sieve confinement effect and exhibits high activity in CO oxidation. However, its molecular sieve coating layer is mainly chemically protective and does not have an independent physical filter layer, so it cannot effectively intercept submicron-sized particles in the desulfurized flue gas, and there is still a risk of surface blockage during long-term operation. Patent CN121103420A uses a molecular sieve support to load noble metals such as Pt and Pd through ion exchange, and has the properties of resistance to SO2, water, HCl and alkali metal poisoning. However, its monolayer structure exposes the active components directly to the flue gas, and heavy metal ions (such as Pb and Zn) can still penetrate the support pores, leading to irreversible poisoning. Patent CN119500119A improves the sulfur resistance of Pt / CeO2 catalysts by modifying them with rare earth metals (La, Pr, etc.), but its CeO2 support has limited adsorption capacity for particulate matter and lacks a tiered protection design, making it prone to deactivation due to ash accumulation under high-dust conditions in sintering flue gas. Furthermore, patent CN103263918A developed a Pt-PbTiO3 nanocatalyst, using a wet chemical method to obtain highly dispersed Pt particles to improve low-temperature activity; however, the PbTiO3 support lacks a targeted filter coating, making it difficult to resist particulate matter erosion and heavy metal deposition. While patent CN117643917A proposes a catalytic filter media concept, achieving strong bonding between the catalyst and filter media through in-situ growth to synergistically remove dioxins and particulate matter, it focuses on dioxin treatment but does not optimize CO oxidation active sites, and the lack of a tiered design between the filter media layer and the active layer results in low CO mass transfer efficiency.

[0004] In summary, the core deficiency of existing technologies lies in the fact that the catalyst structure design does not fully consider the complex pollutant environment after sintering flue gas desulfurization. Specifically, fine particulate matter (particle size <10 μm) and heavy metal ions (such as As, Pb, Cd) generated during the desulfurization process can easily penetrate the pre-dust removal device and interact strongly with the active sites on the catalyst surface. Particulate matter covering the active centers hinders reactant diffusion, while heavy metals occupy the sites of precious metals such as Pt and Pd through chemical adsorption, causing irreversible poisoning. Although some existing technologies attempt to improve resistance to chemical poisoning through molecular sieve coating or ion exchange, they all lack an independent physical protective layer and cannot prevent particulate matter deposition. In addition, although the filter design of patent CN117643917A focuses on particulate matter interception, it is not efficiently coupled with the CO oxidation active layer and is mismatched with the application scenario. Furthermore, the mismatch in the thermal expansion coefficients of single-layer catalysts can easily lead to coating peeling, further shortening their lifespan.

[0005] Therefore, existing CO catalysts have three major bottlenecks in their application after sintering flue gas desulfurization: poor resistance to poisoning, short lifespan, and high maintenance costs. How to provide a new catalyst that combines high catalytic activity with long-term resistance to poisoning is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a layered filter catalyst for the catalytic oxidation of CO in flue gas, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A layered catalyst for the catalytic oxidation of CO in flue gas comprises, from the inside out, a molecular sieve filter material protective layer, a Pt-W / TiO2 active catalyst layer, a cordierite support layer, a Pt-W / TiO2 active catalyst layer, and a molecular sieve filter material protective layer; The Pt-W / TiO2 active catalytic layer is supported on the surface of the cordierite support layer; The molecular sieve filter material protective layer is coated on the surface of the active catalyst layer.

[0008] Beneficial effects: The layered catalyst provided by this invention uses a layered structure design of "active catalyst layer - filter material protective layer". It uses cordierite carrier layer as support skeleton and Pt-W / TiO2 as active component layer as CO oxidation core to achieve efficient CO oxidation. The outer molecular sieve filter material protective layer intercepts particulate matter and heavy metals in flue gas, fundamentally solving the problem of catalyst deactivation under complex pollutant environment after desulfurization. It achieves efficient CO removal and long-term stable operation of catalyst, providing a low-cost and highly reliable technical solution for deep treatment of sintering flue gas.

[0009] More preferably, the overall loading of the molecular sieve filter media protective layer of the filter media layered catalyst is 100~300 g / m³. 2 This ensures high activity and low pressure drop.

[0010] Preferably, the cordierite carrier layer includes a honeycomb pore structure with a pore size of 20-100 mesh, more preferably 20 mesh, 30 mesh, 40 mesh, 50 mesh or 100 mesh.

[0011] Beneficial Effects: This invention uses cordierite honeycomb ceramic as a carrier, mainly utilizing its low coefficient of thermal expansion and high mechanical strength. The pore size range of 20-100 mesh has been optimized: Pores that are too large (>100 mesh) result in insufficient specific surface area, limiting the loading of active components; pores that are too small (<20 mesh) cause a sharp increase in pressure drop when flue gas passes through, increasing fan energy consumption. This range maximizes the adhesion area of ​​the active layer while ensuring gas throughput.

[0012] Preferably, in the Pt-W / TiO2 active catalyst layer, the Pt loading is 0.05~0.2 wt.% and the W loading is 0.5~5 wt.%.

[0013] More preferably, the Pt loading is 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.15 wt%, and 0.2 wt%; the W loading is 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, and 5 wt%; and the molecular sieve filter material protective layer has a loading of 100 g / m³. 2 150 g / m 2 200g / m 2 250 g / m 2 300 g / m 2 .

[0014] More preferably, the Pt-W / TiO2 active catalyst layer further includes rare earth metal La, and the loading of La is 0.5 wt%.

[0015] Beneficial effects: This invention constructs a Pt-W bimetallic synergistic active center. Pt serves as the main active site responsible for CO adsorption and oxidation. The introduction of W is not an inert filling, but rather modulates the d-band center of Pt through electronic effects, weakening the strong chemisorption of SO2 and heavy metals (such as Pb) on the Pt surface, thereby significantly improving the resistance to poisoning. In addition, the addition of 0.5 wt% La aims to utilize the oxygen vacancy effect of rare earth metals to promote the dissociation and adsorption of O2, further reducing the low-temperature ignition temperature.

[0016] Preferably, the protective layer of the molecular sieve filter material is SAPO-34 or SAPO-18 molecular sieve; The thickness of the molecular sieve filter material protective layer is 1~3μm, and the micropore diameter is 0.3~0.4 nm.

[0017] Beneficial effects: The molecular sieve filter material protective layer in this invention is grown in situ and coated on the surface of the active layer. Its microporous structure (pore size 0.3~0.4 nm) can selectively intercept submicron-sized particulate matter (such as desulfurization by-products and heavy metal compounds) in flue gas, while allowing CO and O2 small molecules to diffuse to the active site, thus achieving synergy between physical shielding and chemical protection.

[0018] A method for preparing a layered catalyst for the catalytic oxidation of CO in flue gas includes the following steps: The active layer sol was loaded onto the cordierite carrier layer by vacuum impregnation, and after calcination, a Pt-W / TiO2 active catalytic layer was formed, thus obtaining the Pt-W / TiO2 matrix. The Pt-W / TiO2 matrix was then immersed in the initial gel of the molecular sieve to grow a molecular sieve in situ. After calcination and reduction, the molecular sieve was activated to form a molecular sieve filter material protective layer, thus obtaining the layered catalyst of the filter material.

[0019] Beneficial effects: This invention employs an in-situ growth process, enabling the formation of strong chemical bonds (Si-O-Ti bonds) between the molecular sieve filter material protective layer and the Pt-W / TiO2 active catalyst layer, thus solving the problem of easy coating detachment in traditional physical coating processes. This integrated structure ensures the structural stability of the catalyst under the high-velocity scouring of industrial flue gas.

[0020] Preferably, the vacuum impregnation process involves a vacuum degree of -0.08 to -0.10 MPa, a time of 20 to 40 min, and a temperature of 20 to 40 °C.

[0021] Beneficial effects: This vacuum range completely eliminates air from the cordierite honeycomb ceramic channels, removing bubble obstruction. The negative pressure driving force allows the Pt-W / TiO2 sol to penetrate deeply into the support rather than merely adhering to the surface, significantly improving the loading and distribution uniformity of the active components. Simultaneously, controlling the temperature below 40 ℃ effectively suppresses the volatilization of ethanol solvent in the sol, maintaining suitable viscosity and flowability, preventing "pore sealing" caused by premature gelation at the pore openings, and ensuring consistent activity throughout the catalyst.

[0022] More preferably, the method for preparing the active layer sol includes the following steps: Titanium source, platinum salt and tungsten salt were dissolved in a mixed solvent at a molar ratio of Ti:Pt:W = 1:(0.002~0.015):(0.002~0.02). The mixture was stirred and hydrolyzed at 50-70 °C for 3-6 h. After aging for 10-16 h, a binder was added to form a homogeneous sol.

[0023] More preferably, the molar ratio of the titanium source, platinum salt, and tungsten salt is 1:0.002:0.002, 1:0.005:0.008, 1:0.01:0.01, 1:0.012:0.015, or 1:0.015:0.02.

[0024] More preferably, the titanium source is tetraisopropyl titanate or tetrabutyl titanate.

[0025] The platinum salt is chloroplatinic acid (H2PtCl6) or platinum nitrate (PtNO3).

[0026] The tungsten salt is ammonium tungstate or ammonium metatungstate.

[0027] The binder is silica sol, and the amount added is 3-8% of the total mass, more preferably 3%, 4%, 5%, 6%, 7% or 8%.

[0028] The mixed solvent is obtained by mixing anhydrous ethanol and acetylacetone in a volume ratio of (2~4):1, more preferably 2:1, 2.5:1, 3:1, 3.5:1 or 4:1.

[0029] More preferably, the hydrolysis temperature is 50 ℃, 55 ℃, 60 ℃, 65 ℃ or 70 ℃; the hydrolysis time is 3 h, 4 h, 5 h or 6 h; and the aging time is 10 h, 12 h, 14 h or 16 h.

[0030] Beneficial effects: This sol formulation is designed to achieve atomic-level dispersion of Pt and W on a TiO2 support. Acetylacetone, as a chelating agent, effectively controls the hydrolysis rate of titanium alkoxides, preventing the aggregation or sedimentation of Pt and W precursors. The addition of a silica sol binder enhances the adhesion of the sol to the support surface, preventing coating cracking after calcination.

[0031] Preferably, the calcination temperature is 500-600 ℃, more preferably 500 ℃, 520 ℃, 550 ℃, 580 ℃ or 600 ℃, and the calcination time is 3-6 h, more preferably 3 h, 4 h, 5 h or 6 h.

[0032] More preferably, the calcination atmosphere is air, and the heating rate is 5 °C / min.

[0033] More preferably, the calcination process further includes a drying step, wherein the drying conditions are 80-120°C for 6-12 hours; more preferably, the drying temperature is 80°C, 90°C, 100°C, 110°C or 120°C; and the drying time is 6 hours, 8 hours, 10 hours or 12 hours.

[0034] Beneficial effects: The above-mentioned calcination steps are crucial for transforming amorphous sol into anatase TiO2 support. The temperature range of 500-600 ℃ ensures the integrity of TiO2 crystal transformation while preventing Pt particle sintering and growth due to excessively high temperatures. The stepped drying and calcination process effectively eliminates stress caused by solvent evaporation, ensuring a crack-free coating.

[0035] More preferably, the initial molecular sieve gel comprises the following raw materials: silicon source, aluminum source, phosphorus source, template agent, and deionized water; The amount of raw materials added is obtained by adjusting the molar ratio of Si, Al, P, template agent and H2O to (1~5):(4~14):(2~16):(3~10):(80~200), more preferably 1:4:2:3:80, 2:8:6:5:120, 3:10:10:7:150, 4:12:14:9:180 or 5:14:16:10:200.

[0036] The silicon source is one or more of silica sol, fumed silica, or tetraethyl orthosilicate; The aluminum source is one or more of aluminum isopropoxide, boehmite, or aluminum sulfate. The phosphorus source is one or both of phosphoric acid or ammonium dihydrogen phosphate. The template agent is one or both of tetraethylammonium hydroxide (TEAOH) or morpholine.

[0037] Preferably, the temperature for in-situ growth of the molecular sieve is 160-200℃, more preferably 160℃, 170℃, 180℃, 190℃ or 200℃; and the time is 2-5 days, more preferably 2 days, 3 days, 4 days or 5 days.

[0038] Beneficial effects: The thickness of the molecular sieve layer in this invention is controlled by the reaction time. The thickness is 1-2 μm after 2-3 days of reaction and 2-3 μm after 4-5 days of reaction. This temperature range ensures the complete formation of the SAPO molecular sieve framework structure.

[0039] Preferably, the calcination reduction is performed by calcining at 400 °C for 4 h in an O2 / N2 atmosphere containing 3-25% oxygen, followed by reduction at 400 °C for 4 h in an H2 / N2 atmosphere containing 1-7% hydrogen.

[0040] More preferably, the O2 concentration is 3%, 10%, 15%, 20% or 25%; and the H2 concentration is 1%, 3%, 5% or 7%.

[0041] Beneficial effects: This two-step process aims to precisely control the valence state of Pt. Specifically, calcination in an oxygen-containing atmosphere completely removes the organic template agent within the molecular sieve channels, clearing the microporous pathways; the second step, reduction in a hydrogen atmosphere, converts the oxidized Ptⁿ into its oxidized state. + Reduced to highly active metallic Pt 0 This is the true active center where the CO oxidation reaction occurs.

[0042] Preferably, the calcination and reduction process further includes a step of removing residual template agent, wherein the residual template agent is removed by treating the sample at 300°C for 2 hours in a nitrogen atmosphere.

[0043] Beneficial effects: Low-temperature nitrogen treatment, as an auxiliary method, can gently remove physically adsorbed organic matter without damaging the molecular sieve framework, and protect the active layer from high-temperature impact.

[0044] Application of a layered filter media catalyst for CO catalytic oxidation of flue gas in the catalytic oxidation of CO in steel sintering flue gas.

[0045] More preferably, the CO concentration in the sintering flue gas of the steelmaking process is 5000~10000 mg / m³. 3 SO2 concentration ≤ 200 ppm, particulate matter concentration ≤ 50 mg / m³ 3 airspeed 10,000 h -1 .

[0046] More preferably, the reaction temperature during the application process is 180-250℃.

[0047] Beneficial effects: The application parameter range is matched to the actual operating conditions of steel sintering flue gas. The reaction temperature window of 180-250℃ avoids the flue gas dew point corrosion zone, while utilizing the heat energy of the sintering flue gas itself, eliminating the need for additional heating. The monolithic catalyst is designed for 10,000 h... -1 It can maintain a low pressure drop (<500 Pa) even at high air speeds, fully meeting the online operation requirements of industrial plants.

[0048] Compared with the prior art, the present invention has the following advantages and technical effects: This invention utilizes the Pt-W electronic synergistic effect to reduce the activation energy of CO oxidation, lowering the ignition temperature by 20-30 °C compared to traditional Pt / TiO2 catalysts, achieving both high catalytic activity and low-temperature ignition. Secondly, in the layered filter catalyst provided by this invention, the molecular sieve filter layer can intercept particulate matter and heavy metals through size sieving, while the oxygen storage function of W dynamically removes poisons. Under conditions of SO2 and Pb coexistence, the activity retention rate is >90%, and the lifespan is extended to over 12 months, demonstrating excellent resistance to poisoning. Furthermore, the layered filter catalyst provided by this invention uses an in-situ growth process to chemically bond the active layer and protective layer, preventing coating peeling. The integral design has a pressure drop of <500 Pa, exhibiting strong structural stability and suitability for industrial sintering flue gas systems. Finally, this invention utilizes W to partially replace precious metals, achieving ultra-low Pt usage, while the filter layer is regenerable, reducing replacement frequency and making it suitable for widespread application. Attached Figure Description

[0049] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1This is a schematic diagram of the honeycomb-like pore structure of the Pt-W / TiO2-filter media layered catalyst obtained in Example 1 of the present invention; Figure 2 This is a schematic diagram of the structure of a single pore in the Pt-W / TiO2-filter media layered catalyst obtained in Example 1 of the present invention. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels; Among them, the cordierite honeycomb ceramic carrier was purchased from Puli Environmental Company; The initial gel of the molecular sieve includes the following raw materials: silicon source, aluminum source, phosphorus source, template agent and deionized water. The silicon source is tetraethyl orthosilicate, the aluminum source is aluminum isopropoxide and aluminum sulfate, and the phosphorus source is phosphoric acid and ammonium dihydrogen phosphate. The proportion of each raw material is adjusted according to the mass ratio of Si, Al, P, TEAOH and H2O.

[0053] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3℃.

[0054] Example 1 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 °C. After impregnation, it was dried at 100 °C for 8 h and then calcined at 550 °C for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶5∶120) and hydrothermally reacted at 180 ℃ for 3 days. After the reaction, it was washed and dried, calcined at 400 ℃ for 4 h in a 10% O2 / N2 atmosphere, and then reduced at 400 ℃ for 4 h in a 3% H2 / N2 atmosphere to form a molecular sieve filter material protective layer with a thickness of 1.5 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst, the structure of which is as follows: Figure 1 and 2 As shown.

[0055] Example 2 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.0005 mol chloroplatinic acid and 0.002 mol ammonium tungstate in a mixed solvent of 160 mL anhydrous ethanol and 40 mL acetylacetone, add 6 g silica sol, stir and hydrolyze at 55 °C for 5 h, and age at room temperature for 14 h to obtain active layer sol; (2) The active layer sol was loaded onto a 50-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 25 min at 25 ℃. After impregnation, it was dried at 110 ℃ for 5 h and then calcined at 520 ℃ for 4 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶morpholine∶H2O=3∶10∶8∶6∶150) and hydrothermally reacted at 190 °C for 4 days. After the reaction was completed, the matrix was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 15% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 5% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 2.0 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0056] Example 3 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetrabutyl titanate, 0.0015 mol platinum nitrate and 0.0015 mol ammonium tungstate in a mixed solvent of 140 mL anhydrous ethanol and 60 mL acetylacetone, add 4 g silica sol, stir and hydrolyze at 65 °C for 3 h, and age at room temperature for 10 h to obtain active layer sol; (2) The active layer sol was loaded onto a 25-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 35 min at 25 ℃. After impregnation, it was dried at 90 ℃ for 10 h and then calcined at 580 ℃ for 3 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=4∶12∶12∶8∶180) and hydrothermally reacted at 170 °C for 5 days. After the reaction was completed, the matrix was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 20% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 7% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 3.0 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0057] Example 4 A method for preparing a Pt-W / TiO2-filter media stratified catalyst differs from Example 1 only in that the amounts of chloroplatinic acid and ammonium tungstate added are changed, along with the type of template agent and the hydrothermal reaction temperature. The method specifically includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.0005 mol chloroplatinic acid and 0.003 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; Step (2) The active layer sol is loaded onto a 30-mesh cordierite honeycomb ceramic carrier using a vacuum impregnation method. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier is impregnated in the active layer sol obtained in step (1) at 25 ℃ for 30 min. After impregnation, it is dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer, thus obtaining the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶tetraethylammonium hydroxide∶H2O=2∶8∶6∶5∶120) and hydrothermally reacted at 170 °C for 5 days. After the reaction was completed, the matrix was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 10% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 3.0 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0058] Example 5 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.0015 mol chloroplatinic acid and 0.005 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol. (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in a mixed gel of SAPO-34 and SAPO-18 in a mass ratio of 1:1 and hydrothermally reacted at 200 °C for 2 days. After the reaction was completed, the matrix was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 10% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 1.0 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0059] Example 6 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetrabutyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 65 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 100-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 20 h at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=5∶14∶6∶5∶120) and hydrothermally reacted at 180 °C for 3 days. After the reaction was completed, the matrix was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 10% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 1.5 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0060] Example 7 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶32∶5∶120) and hydrothermally reacted at 130 °C for 2 days. After the reaction was completed, it was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 5% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 1.0 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0061] Example 8 A method for preparing a Pt-W / TiO2-filter media layered catalyst differs from Example 1 only in that 0.001 mol of lanthanum nitrate (La loading 0.5 wt%) is added in step (1), and SAPO-34 is used as the initial molecular sieve gel in step (3). The method specifically includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (SAPO-34) and hydrothermally reacted at 180 °C for 3 days. After the reaction was completed, it was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 10% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 1.5 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0062] Example 9 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶5∶400) and hydrothermally reacted at 180 °C for 3 days. After the reaction was completed, the matrix was washed and dried, calcined at 600 °C for 3 h in an atmosphere of 10% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 1.5 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0063] Example 10 A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 h at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶6∶120) and hydrothermally reacted at 190 °C for 5 days. After the reaction was completed, it was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 10% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer with a thickness of 3 μm, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0064] Comparative Example 1 The only difference from Example 1 is that tungsten salt is not added in step (1), and the specific steps include: (1) Dissolve 0.1 mol tetraisopropyl titanate and 0.001 mol chloroplatinic acid in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol. (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-TiO2 active catalyst layer and obtain a Pt-TiO2 matrix. (3) The Pt-TiO2 matrix was immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶5∶120) and hydrothermally reacted at 180 °C for 3 days. After the reaction was completed, the matrix was washed and dried, calcined at 400 °C for 4 h in an atmosphere of 10% O2 / N2, and then reduced at 400 °C for 4 h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer, thus obtaining the filter material layering catalyst.

[0065] Comparative Example 2 The only difference from Example 1 is that in step (3), in-situ growth of the molecular sieve filter layer is not performed. Specifically, the following steps are included: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix.

[0066] Comparative Example 3 The only difference from Example 1 is that the molecular sieve filter media layer and the active layer are physically mixed and then coated, specifically including the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶5∶120) and the active layer sol were physically mixed at a mass ratio of 1:1 and coated onto a 30-mesh cordierite honeycomb ceramic carrier. The mixture was dried at 100 °C for 8 h and calcined at 550 °C for 5 h to obtain the catalyst.

[0067] Comparative Example 4 The only difference from Example 1 is that it does not include the active layer sol, and specifically includes the following steps: A 30-mesh cordierite honeycomb ceramic carrier was immersed in an initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶5∶120) and subjected to a hydrothermal reaction at 180 ℃ for 3 days. After the reaction, the carrier was washed and dried, calcined at 400 ℃ for 4 h in a 10% O2 / N2 atmosphere, and then reduced at 400 ℃ for 4 h in a 3% H2 / N2 atmosphere to obtain the filter material stratification catalyst.

[0068] Comparative Example 5 The only difference from Example 1 is that step (3) does not include the hydrothermal reaction process, and specifically includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The Pt-W / TiO2 matrix is ​​immersed in the initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶5∶120), calcined at 400℃ for 4h in an atmosphere of 10% O2 / N2, and then reduced at 400℃ for 4h in an atmosphere of 3% H2 / N2 to form a molecular sieve filter material protective layer, thus obtaining the catalyst.

[0069] Comparative Example 6 The only difference from Example 1 is that in step (3), the initial molecular sieve gel is coated onto the Pt-W / TiO2 matrix, specifically including the following steps: A method for preparing a Pt-W / TiO2-filter media stratified catalyst includes the following steps: (1) Dissolve 0.1 mol tetraisopropyl titanate, 0.001 mol chloroplatinic acid and 0.001 mol ammonium tungstate in a mixed solvent of 150 mL anhydrous ethanol and 50 mL acetylacetone, add 5 g silica sol, stir and hydrolyze at 60 °C for 4 h, and age at room temperature for 12 h to obtain active layer sol; (2) The active layer sol was loaded onto a 30-mesh cordierite honeycomb ceramic carrier by vacuum impregnation. Specifically, under vacuum conditions, the cordierite honeycomb ceramic carrier was impregnated in the active layer sol obtained in step (1) for 30 min at 25 ℃. After impregnation, it was dried at 100 ℃ for 8 h and then calcined at 550 ℃ for 5 h to form a Pt-W / TiO2 active catalyst layer and obtain the Pt-W / TiO2 matrix. (3) The initial molecular sieve gel (Si∶Al∶P∶TEAOH∶H2O=2∶8∶6∶5∶120) was coated on the surface of the Pt-W / TiO2 matrix at 200 g / m 2 After drying at 100 °C for 8 h, a molecular sieve filter material protective layer is formed, thus obtaining the Pt-W / TiO2-filter material layered catalyst.

[0070] Technical effects: 1. The Pt loading, W loading, and filter bed loading of the catalysts obtained in Examples 1-10 and Comparative Examples 1-6 were determined. See Table 1 for details. Table 1 As can be seen from Table 1, the present invention achieves the optimal balance between catalyst structure and performance by precisely controlling the loading of each component.

[0071] First, the introduction of W is key to improving anti-poisoning performance. Comparing Example 1 (containing W) and Comparative Example 1 (without W), both had a Pt loading of 0.1 wt%, but only Example 1 exhibited the superior anti-SO2 and anti-Pb performance shown in Table 2 (T90 only 210 °C, retention rate 94.5%). This proves that W, as an additive, is not an inert filler, but rather effectively inhibits the strong chemisorption of poisons by forming an electronic synergistic effect with Pt. Meanwhile, Examples 4 (W loading 3 wt%) and 5 (W loading 5 wt%) show that appropriately increasing the W content can further enhance the stability of the active component without causing active site coverage problems due to excessive loading.

[0072] Secondly, the loading of the molecular sieve filter media protective layer is strictly controlled at 100~300 g / m². 2 Within this range, this is the core design that balances "dust removal efficiency" and "mass transfer resistance". In Example 10, the filter media loading reached 300 g / m³. 2 The dust removal efficiency is >99.5% as shown in Table 2; while the load in Example 7 is 170 g / m³. 2 It can still maintain high activity. If the loading is too low (e.g., below 100g / m³), it will remain highly active. 2 (Not listed), a continuous and dense protective layer cannot be formed; if the concentration is too high (e.g., exceeding 300 g / m³), a continuous and dense protective layer cannot be formed. 2 This will significantly increase the resistance to gas diffusion, leading to an increase in pressure drop and ignition temperature.

[0073] Furthermore, the ultra-low Pt loading design demonstrates economic efficiency. In Examples 1-10, the Pt loading was controlled at an extremely low level of 0.05~0.15 wt%, far lower than that of traditional commercial catalysts (typically >0.5 wt%). In particular, Example 4, with only 0.05 wt% Pt, still maintained good catalytic activity thanks to the synergistic effect of W and the protection of the filter layer, significantly reducing the cost of precious metals.

[0074] Finally, the integrity of the layered structure is crucial. Comparative Example 2, lacking a filter media layer (with a loading of 0), resulted in direct exposure of the active layer, leading to a sharp decline in the anti-poisoning ability shown in Table 2. Comparative Example 3, employing a physical mixing method, had a filter media loading of only 150 g / m³. 2Furthermore, the weak bonding force prevents it from providing long-term protection. This demonstrates that the integrated "active layer-protective layer" structure constructed using the in-situ growth process of this invention is a necessary condition for ensuring the long-life operation of the catalyst.

[0075] In summary, the data in Table 1 fully verify the rationality and necessity of the loading range in the claims, and the optimized combination of the contents of each component is the material basis for achieving the technical effect of "high activity, long life and low cost" of this invention.

[0076] 2. The CO catalytic oxidation performance of the catalysts obtained in Examples 1-10 and Comparative Examples 1-6 was tested. The flue gas composition was [CO]=5000ppm, [O2]=10%, [SO2]=200ppm, [Pb]=10ppm, and N2 equilibrium was maintained; the space velocity was 10000 h⁻¹. -1 The temperature range was 150~300 ℃. The CO conversion results are shown in Table 2.

[0077] Table 2 As shown in Table 2, the Pt-W / TiO2-filter media layered catalysts provided in Examples 1-10 of this invention exhibit excellent CO catalytic oxidation performance and anti-poisoning ability in complex sintering flue gas containing SO2 and Pb. Specifically, Example 1 achieved complete CO conversion at 195 °C in an SO2-free atmosphere (T... 90 Under an atmosphere containing SO2 (200 ppm) T 90 The temperature was only raised to 210 °C, and the activity retention rate was as high as 94.5% after Pb poisoning test; while Example 5, by optimizing the W loading (5 wt%), achieved a higher activity retention rate under the same conditions. 90 Further reducing the temperature to 200 °C, the activity retention rate after Pb poisoning increased to 95.2%, highlighting the enhanced anti-poisoning effect of high W content. Example 8, through the introduction of La rare earth metal modification, T... 90 The temperature was as low as 190 °C, indicating that the oxygen vacancy effect of rare earth metals can synergistically enhance low-temperature activity.

[0078] A comparative analysis of the overall data from the embodiments and comparative examples in Table 2 reveals that, firstly, the introduction of W in this invention exhibits an electronic modulation effect: the introduction of W (loading amount 0.5~5 wt%) in all embodiments significantly enhances the anti-poisoning performance of Pt. For example, Example 4 (Pt loading amount 0.05 wt%, W loading amount 3 wt%) still maintains T even with low amounts of precious metals. 90 ≤205 ℃ ， Comparative Example 1 (without W) in the presence of SO2, T 90The temperature spiked to 265 °C, but the activity retention rate was only 72.6%, demonstrating that W improved oxygen activation capacity and anti-poisoning stability by optimizing the d-band center of Pt. Secondly, the molecular sieve filter layer plays a crucial role: Examples 2 (SAPO-18 filter media), 3 (SAPO-34 filter media), and 10 (thick filter layer) show that different molecular sieve types and thicknesses (1~3 μm) can effectively intercept particulate matter, resulting in an activity retention rate >91% after Pb poisoning. In contrast, Comparative Example 2 (without filter layer) showed a lower activity retention rate in dusty flue gas. 90 At 280 °C, the activity retention rate was only 68.4%, indicating that physical protection of the filter media layer is indispensable. Furthermore, the in-situ growth process in this invention has significant advantages: Examples 6 (carrier pore size optimization) and 9 (high-temperature calcination) achieve strong bonding between the filter media layer and the active layer through in-situ growth, with a load decay of <5% in long-term testing. In contrast, Comparative Example 3 (physically mixed filter media) has a weak bonding force, resulting in a filter media layer shedding rate >20% and an activity retention rate of only 81.2%, demonstrating the superiority of the in-situ growth process in structural stability. Simultaneously, the various parameters in this invention exhibit synergistic optimization effects: Examples 7 (short hydrothermal time) and 10 (long hydrothermal time) show that the filter media layer growth conditions need to balance activity and stability; Examples 5 and 8 demonstrate that the synergy between W and rare earth metals can further enhance anti-poisoning ability, with Example 8 showing that T in the presence of SO2... 90 At only 205 ℃, the activity retention rate is 93.8%.

[0079] In summary, this invention, through the organic combination of the Pt-W electronic synergistic effect and the physical protection of the filter material obtained by utilizing the initial gelation of molecular sieves, systematically achieved efficient catalytic oxidation and long-term stable operation of CO in sintering flue gas in Examples 1-10. All examples met the T... 90 With performance indicators of ≤210 ℃ and SO2 / Pb poisoning resistance retention rate >88%, and by solving the problem of poisoning and deactivation of traditional catalysts in flue gas after desulfurization through layered structure design, it provides a reliable solution for industrial applications.

[0080] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A filter material layered catalyst for catalytic oxidation of CO in flue gas, characterized by, From the inside out, it includes a molecular sieve filter media protective layer, a Pt-W / TiO2 active catalytic layer, a cordierite support layer, a Pt-W / TiO2 active catalytic layer, and a molecular sieve filter media protective layer. The Pt-W / TiO2 active catalytic layer is supported on the surface of the cordierite support layer; The molecular sieve filter material protective layer is coated on the surface of the Pt-W / TiO2 active catalyst layer.

2. The layered catalyst for CO catalytic oxidation in flue gas according to claim 1, characterized in that, The cordierite carrier layer includes a honeycomb-like pore structure with a pore size of 20-100 mesh.

3. The layered catalyst for catalytic oxidation of CO in flue gas according to claim 1, characterized in that, In the Pt-W / TiO2 active catalyst layer, the Pt loading is 0.05~0.2 wt.% and the W loading is 0.5~5 wt.%.

4. The layered catalyst for catalytic oxidation of CO in flue gas according to claim 1, characterized in that, The protective layer of the molecular sieve filter media is SAPO-34 or SAPO-18 molecular sieve; The thickness of the molecular sieve filter material protective layer is 1~3μm, and the micropore diameter is 0.3~0.4 nm.

5. A method for preparing a layered catalyst for catalytic oxidation of CO in flue gases according to any one of claims 1 to 4, characterized in that, Includes the following steps: The active layer sol was loaded onto the cordierite carrier layer by vacuum impregnation, and after calcination, a Pt-W / TiO2 active catalytic layer was formed, thus obtaining the Pt-W / TiO2 matrix. The Pt-W / TiO2 matrix was then immersed in the initial gel of the molecular sieve to grow the molecular sieve in situ. After calcination and reduction, a molecular sieve filter material protective layer was formed, thus obtaining the layered catalyst of the filter material.

6. The method for preparing a layered catalyst for catalytic oxidation of CO in flue gas according to claim 5, characterized in that, The calcination temperature is 500-600℃, and the time is 3-6 hours.

7. The method for preparing a layered catalyst for catalytic oxidation of CO in flue gas according to claim 5, characterized in that, The in-situ growth of molecular sieves is carried out at a temperature of 160-200℃ for 2-5 days.

8. The method for preparing a layered catalyst for catalytic oxidation of CO in flue gas according to claim 5, characterized in that, The roasting and reduction process involves roasting at 400 °C for 4 h in an O2 / N2 atmosphere containing 3-25% oxygen, followed by reduction at 400 °C for 4 h in an H2 / N2 atmosphere containing 1-7% hydrogen.

9. The application of the filter media layered catalyst for CO catalytic oxidation of flue gas as described in any one of claims 1-4 in the CO catalytic oxidation of sintering flue gas in iron and steel.

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