Anti-aging high-activity CO oxidation catalyst and preparation method thereof

Abstract

The present invention discloses an anti-aging, highly active CO oxidation catalyst and its preparation method, relating to the field of catalyst technology. The technical solution comprises the following components by mass percentage: 0.1-2% of an iridium-ruthenium alloy active component, 80-90% of a tantalum-doped zirconia carrier, and 10-20% of a composite additive; the composite additive is a composite oxide of MoO3 and Nb2O5, with a mass ratio of MoO3 to Nb2O5 of (1-3):1. By optimizing the active component, carrier, and additive system, combined with an innovative preparation process, the present invention significantly improves the catalyst's CO conversion rate and sulfur poisoning resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to an aging-resistant high-activity CO oxidation catalyst and a preparation method thereof. Background Art

[0002] The sintering process, a critical step in steel production, produces flue gas containing large amounts of harmful gases such as carbon monoxide (CO) and sulfur dioxide (SO2). These gases not only cause serious environmental pollution but also pose a threat to human health. To effectively remove these harmful gases, CO oxidation catalysts based on precious metals such as platinum (Pt) and palladium (Pd) have traditionally been used.

[0003] However, the traditional Pt / Pd noble metal catalyst system faces numerous challenges in practical application. First, the high price of precious metals such as Pt and Pd leads to high catalyst costs, which increases production costs for steel companies. Second, these catalysts are sensitive to sulfur poisoning and easily deactivate in sulfur-containing environments, reducing catalytic efficiency and service life. Furthermore, insufficient high-temperature stability is a major drawback. In high-temperature sintering environments, the catalysts are prone to structural changes or sintering, further affecting catalytic performance.

[0004] In addition to the aforementioned issues, conventional catalyst supports and additive systems also have limitations in their ability to regulate oxygen vacancies. Oxygen vacancies are a crucial component of active sites on the catalyst surface and play a crucial role in the adsorption and activation of CO. However, this limited ability of supports and additives to regulate oxygen vacancies results in insufficient catalytic activity, making it difficult to meet the requirements for efficient purification.

[0005] In view of the above problems, the development of an efficient, stable and sulfur-poisoning-resistant CO oxidation catalyst has important practical significance and scientific research value. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide an aging-resistant and highly active CO oxidation catalyst and a preparation method thereof. By optimizing the active components, carrier and auxiliary agent system and combining an innovative preparation process, the CO conversion rate and sulfur poisoning resistance of the catalyst are significantly improved.

[0007] The technical solution of the present invention is:

[0008] On the one hand, the present invention provides an aging-resistant and highly active CO oxidation catalyst, comprising the following components in mass percentage: 0.1-2% of an iridium-ruthenium alloy active component, 80-90% of a tantalum-doped zirconia carrier, and 10-20% of a composite additive; the composite additive is a composite oxide of MoO3 and Nb2O5, and the mass ratio of MoO3 to Nb2O5 is (1-3):1.

[0009] Preferably, in the iridium-ruthenium alloy active component, the mass ratio of iridium to ruthenium is 1:(1-5).

[0010] Preferably, in the tantalum-doped zirconia carrier, the molar ratio of zirconium to tantalum is (9-19):1.

[0011] In another aspect, the present invention provides a method for preparing the above-mentioned aging-resistant high-activity CO oxidation catalyst, comprising the following steps:

[0012] S1 Support Preparation: Tantalum-doped zirconia support was prepared by sol-gel combustion synthesis;

[0013] S2 carrier pretreatment: calcining the tantalum-doped zirconia carrier by gradient calcination method, first raising the temperature to 400-450℃ at a rate of 5-10℃ / min, keeping it warm for 1-2h, then raising the temperature to 550-600℃ at a rate of 3-5℃ / min, keeping it warm for 2-3h;

[0014] S3 composite additive impregnation: using ammonium tartrate as a complexing agent, MoO3 was loaded on the tantalum-doped zirconia support by the first impregnation, followed by a second impregnation using ultrasound-assisted microwave drying to load Nb2O5 on the tantalum-doped zirconia support;

[0015] S4 active component loading: The iridium-ruthenium alloy active component is loaded on a tantalum-doped zirconia carrier impregnated with a composite additive using a supercritical CO2 fluid deposition method to obtain an aging-resistant and highly active CO oxidation catalyst.

[0016] Preferably, in step S1, preparing the tantalum-doped zirconia support by the sol-gel combustion synthesis method comprises the following steps:

[0017] (1) Dissolving metal salts: Dissolve zirconium oxynitrate and tantalum pentachloride (TaCl5) in deionized water and stir until transparent; add combustion agent and continue stirring; adjust the pH of the solution to 3-4 to promote complexation reaction and form a uniform sol;

[0018] (2) Gelation and drying: Place the solution in a water bath at 80-90°C and continue stirring to evaporate until it becomes a viscous gel; transfer to an oven for drying to obtain a porous xerogel precursor;

[0019] (3) Combustion synthesis: The porous xerogel precursor is ground into powder to ensure uniformity, the powder is placed in a refractory crucible, and the temperature is raised to 250-300 °C in a muffle furnace at 5-10 °C / min to trigger a self-propagating combustion reaction;

[0020] (4) High temperature calcination: Continue to raise the temperature to 600-800°C and keep it at this temperature for 2-4 hours to completely decompose the organic matter and obtain tantalum-doped zirconia crystals;

[0021] (5) Cooling and grinding: Cool naturally to room temperature and grind again to obtain a tantalum-doped zirconia carrier.

[0022] Preferably, in step (1), the combustion agent is glycine and citric acid in a mass ratio of 1: (2-3); the molar ratio of zirconyl nitrate and tantalum pentachloride is (9-19): 1; the combustion agent and Zr 4+ 、Ta 5+ The molar ratio of the total moles is (1.5-2):1.

[0023] Preferably, in step (2), the drying temperature is 100-110° C. and the drying time is 10-12 h.

[0024] Preferably, in step S3, the first impregnation loading of MoO3 comprises the following steps:

[0025] (1) Solution preparation: Prepare ammonium molybdate ((NH4)6Mo7O) with a concentration of 0.1-0.5 mol / L using deionized water. 24 4H2O) precursor solution, add ammonium tartrate ((NH4)2C4H4O6) at a molar ratio of ammonium tartrate to Mo of (1-2):1, stir until completely dissolved, and adjust the solution pH to 3-5 to inhibit the rapid hydrolysis of MoO3;

[0026] (2) Equal volume impregnation: the precursor solution is added dropwise to the tantalum-doped zirconia support until the pore volume is saturated;

[0027] (3) Static aging: Static aging at room temperature for 6-12 hours in a sealed environment to promote uniform adsorption of Mo complexes;

[0028] (4) Drying and calcination: Dry at 60-80°C for 12 h, slowly remove moisture, and then calcine in a muffle furnace at 400-500°C for 4-5 h at a heating rate of 2-3°C / min to form a MoO3 crystalline phase;

[0029] The secondary impregnation loading of Nb2O5 includes the following steps:

[0030] 1) Solution preparation: Prepare a 0.05-0.2 mol / L ammonium niobium oxalate (NH4NbO(C2O4)2·nH2O) precursor solution using oxalic acid solution;

[0031] 2) Ultrasonic-assisted impregnation: The tantalum-doped zirconia support loaded with the MoO3 precursor was immersed in the niobium oxalate precursor solution and placed in a 40-50 kHz ultrasonic bath for 30-60 minutes;

[0032] 3) Microwave-enhanced drying: Drying is carried out in microwave pulse mode, with a power of 300-600W, starting for 30-40s and stopping for 15-20s, until completely dried;

[0033] 4) Decomposition and crystallization: Pre-sinter at 200-250℃ for 2-3h to decompose organic matter, then heat to 450-550℃ and calcine for 3-4h to form Nb2O5.

[0034] Preferably, in step S4, the supercritical CO2 fluid deposition method includes the following steps:

[0035] (1) Preparation of iridium-ruthenium alloy precursor solution: prepare iridium acetylacetonate (Ir(acac)3) and ruthenium acetylacetonate (Ru(acac)3) solutions with methanol, with the methanol ratio being 5-10 vol.%, and dissolve them with ultrasound assistance until the solution is clear and free of precipitation; filter through a 0.22-0.25 μm organic filter membrane to remove undissolved impurities;

[0036] (2) Preactivation: The tantalum-doped zirconia support loaded with the composite additive is treated at 250-350°C for 1-22 h in a H2 / N2 (5 vol.% H2) atmosphere to enhance the activity of the surface hydroxyl groups;

[0037] (3) Supercritical setting: Place the carrier in a reactor at 40-60°C, 10-15 MPa, and a CO2 flow rate of 0.5-2 L / min, introduce pure CO2 to a supercritical state, and maintain for 30 minutes to exclude air;

[0038] (4) Precursor injection: Inject the iridium-ruthenium alloy precursor solution into the reactor through a high-pressure pump to ensure that CO2 and the precursor are fully mixed;

[0039] (5) Dynamic impregnation: Maintain supercritical conditions for 2-4 hours under stirring conditions to allow the precursor to be uniformly adsorbed into the pores of the support;

[0040] (6) Decompression deposition: Release the pressure (rate ≤ 0.5 MPa / min), CO2 gradually vaporizes, and the precursor is directionally deposited on the support surface;

[0041] (7) Hydrogen reduction: Introduce H2 / Ar mixed gas (H2 accounts for 5-10 vol.%) into a tube furnace, heat it to 300-400℃ at 2℃ / min, and keep it at this temperature for 2-3h to make Ir 3+ 、Ru 3+ Reduce to metallic state; further heat to 450-550℃ and keep warm for 1-2h to promote alloying.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention significantly improves the CO conversion rate and sulfur poisoning resistance of the catalyst by optimizing the active components, carrier and additive system and combining it with an innovative preparation process. It is particularly suitable for high-humidity and high-sulfur sintering flue gas environments.

[0044] 2. The present invention uses Ir-Ru alloy to replace conventional Pt / Pd as the active component. By utilizing the high stability of Ir and the electronic synergistic effect of Ru, the Ir-Ru alloy may form a bimetallic interface structure. The surface-exposed Ir-Ru atomic pairs can provide unique bifunctional active sites. Through the geometric-electronic double synergistic effect, a dynamic balance between CO adsorption strength and oxygen activation ability is achieved, while taking into account high activity, stability and anti-poisoning. In addition, the Ir-Ru alloy inhibits SO2 adsorption through electronic regulation, promotes dynamic desorption of sulfur oxides through interface synergy, and the high stability of Ir prevents deep penetration of sulfate, making it significantly superior to traditional Pt / Pd catalysts in anti-SO2 poisoning performance. At the same time, the present invention develops a tantalum-doped zirconia carrier, through Ta 5+ Stable oxygen vacancies are induced to generate, thereby enhancing the catalyst's ability to activate oxygen and promoting the oxidation of SO2 to easily desorbed SO3, rather than forming stable sulfates, thereby reducing the poisoning of active sites by sulfur species. At the same time, the stable presence of oxygen vacancies can inhibit the dissociative adsorption of water molecules on the carrier surface, reduce the generation of hydroxyl groups, avoid carrier phase changes under hydrothermal conditions, maintain the integrity of the carrier structure, and thus reduce the poisoning of the catalyst by water. In addition, the present invention also constructs a Mo-Nb system, in which MoO3 provides acidic sites and Nb2O5 enhances electron transfer. Through the dual synergy of acidic site activation and electron transfer, all-round optimization of the CO oxidation reaction kinetics is achieved, while giving the catalyst excellent anti-poisoning, thermal stability and wide temperature range adaptability.

[0045] 3. This invention innovatively combines supercritical deposition and gradient calcination technology to achieve highly dispersed loading of active components, thereby forming more interfacial contact points between the active components and the support, forming more "metal-oxide interface" active sites, enhancing the interfacial coordination of the CO oxidation reaction, and improving the reaction activity of the catalyst. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0047] Example 1

[0048] The aging-resistant, highly active CO oxidation catalyst of this embodiment comprises the following components by weight: 1% of an iridium-ruthenium alloy active component (with a mass ratio of iridium to ruthenium of 1:1), 85% of a tantalum-doped zirconia support (with a molar ratio of zirconium to tantalum of 9:1), and 14% of a composite additive. The composite additive is a composite oxide of MoO3 and Nb2O5, with a mass ratio of MoO3 to Nb2O5 of 1:1.

[0049] The preparation method of the aging-resistant high-activity CO oxidation catalyst of this embodiment comprises the following steps:

[0050] S1 Support Preparation: Tantalum-doped zirconium oxide support was prepared by sol-gel combustion synthesis method, including the following steps:

[0051] (1) Dissolving metal salts: dissolve zirconium oxynitrate and TaCl5 in a molar ratio of 9:1 in deionized water and stir until transparent; add glycine and citric acid in a mass ratio of 1:2 to the above solution and continue stirring for 30 minutes; adjust the pH of the solution to 3 with dilute nitric acid to promote the complexation reaction and form a uniform sol; the combustible agent and Zr 4+ 、Ta 5+ The molar ratio of the total moles of is 1.5:1;

[0052] (2) Gelation and drying: The solution was placed in a 90°C water bath and continuously stirred to evaporate until it became a viscous gel; the solution was transferred to an oven and dried at 100°C for 12 h to obtain a porous xerogel precursor;

[0053] (3) Combustion synthesis: The porous xerogel precursor was ground into powder to ensure uniformity, and the powder was placed in a refractory crucible and heated to 250 °C in a muffle furnace at 5 °C / min to trigger the self-propagating combustion reaction;

[0054] (4) High-temperature calcination: Continue to raise the temperature to 600°C and keep it for 4 hours to completely decompose the organic matter to obtain tantalum-doped zirconia crystals;

[0055] (5) Cooling and grinding: Cool naturally to room temperature and grind again to obtain a tantalum-doped zirconia carrier.

[0056] S2 carrier pretreatment: The tantalum-doped zirconia carrier was calcined by a gradient calcination method, firstly raised to 400°C at a rate of 5°C / min, kept warm for 1 hour, and then raised to 600°C at a rate of 3°C / min, kept warm for 2 hours.

[0057] S3 composite auxiliary agent impregnation, wherein the first impregnation loading MoO3 includes the following steps:

[0058] (1) Solution preparation: Prepare a 0.1 mol / L ammonium molybdate precursor solution with deionized water, add ammonium tartrate at a molar ratio of ammonium tartrate to Mo of 1:1, stir until completely dissolved, and adjust the solution pH to 4 with dilute nitric acid to inhibit the rapid hydrolysis of MoO3;

[0059] (2) Equal volume impregnation: the precursor solution is added dropwise to the tantalum-doped zirconia support until the pore volume is saturated;

[0060] (3) Static aging: Static aging for 12 h at room temperature in a sealed environment to promote uniform adsorption of Mo complexes;

[0061] (4) Drying and calcination: Dry at 60°C for 12 h to slowly remove moisture, then calcinate at 500°C in a muffle furnace for 4 h at a heating rate of 3°C / min to form a MoO3 crystal phase;

[0062] The secondary impregnation loading of Nb2O5 includes the following steps:

[0063] 1) Solution preparation: Prepare an ammonium niobium oxalate precursor solution with a concentration of 0.05 mol / L using oxalic acid solution;

[0064] 2) Ultrasonic-assisted impregnation: The tantalum-doped zirconia support loaded with the MoO3 precursor was immersed in the niobium oxalate precursor solution and placed in a 40 kHz ultrasonic bath for 60 min;

[0065] 3) Microwave-enhanced drying: Drying was performed using microwave pulse mode, 30s on, 15s off, at a power of 300W, until completely dry;

[0066] 4) Decomposition and crystallization: Pre-sinter at 200℃ for 3h to decompose organic matter, then heat to 550℃ and calcine for 3h to form Nb2O5.

[0067] S4 Active Component Loading: The iridium-ruthenium alloy active component is loaded on a tantalum-doped zirconia support impregnated with a composite additive using a supercritical CO2 fluid deposition method to obtain an aging-resistant and highly active CO oxidation catalyst. The specific steps include:

[0068] (1) Preparation of iridium-ruthenium alloy precursor solution: iridium acetylacetonate and ruthenium acetylacetonate solutions were prepared with methanol, with the methanol ratio being 5 vol.%, and ultrasonically assisted dissolution (40 kHz, 30 min) was performed until the solution was clear and free of precipitation; the solution was filtered through a 0.22 μm organic filter membrane to remove undissolved impurities;

[0069] (2) Preactivation: The tantalum-doped zirconia support loaded with the composite additive was treated at 250 °C for 2 h in a H2 / N2 (5 vol.% H2) atmosphere to enhance the activity of the surface hydroxyl groups;

[0070] (3) Supercritical setting: Place the carrier in a reactor at 40°C, 15 MPa, and a CO2 flow rate of 0.5 L / min, introduce pure CO2 to a supercritical state, and maintain for 30 min to exclude air;

[0071] (4) Precursor injection: Inject the iridium-ruthenium alloy precursor solution into the reactor through a high-pressure pump to ensure that CO2 and the precursor are fully mixed;

[0072] (5) Dynamic impregnation: Turn on magnetic stirring (500 rpm) and maintain supercritical conditions for 4 h to allow the precursor to be uniformly adsorbed in the pores of the support;

[0073] (6) Decompression deposition: Release the pressure (rate 0.2 MPa / min), CO2 gradually vaporizes, and the precursor is directionally deposited on the support surface;

[0074] (7) Hydrogen reduction: H2 / Ar mixed gas (H2 accounts for 5 vol.%) was introduced into a tube furnace, and the temperature was raised to 300℃ at 2℃ / min and kept at this temperature for 3h to make Ir 3+ 、Ru 3+ Reduce to metallic state; further heat to 550℃ and keep warm for 1h to promote alloying;

[0075] (8) In-situ alloying verification

[0076] XRD analysis: Detect whether the characteristic peaks of Ir-Ru alloy (such as face-centered cubic phase, 2θ≈40.5°, 47.2°) appear.

[0077] TEM-EDS scan: confirm the overlap between Ir and Ru element distributions (correlation coefficient > 0.9 is required).

[0078] The aging-resistant and highly active CO oxidation catalyst prepared in this example was used in a small test to simulate the composition of steel sintering flue gas. The initial activity test conditions were 4000 ppm CO + 15% O2, a space velocity of 100,000 h -1 The anti-poisoning aging test conditions were 4000ppm CO + 15% O2 + 2000ppm SO2 + 1000ppm NO + 50ppm NH3 + 15% H2O. The CO conversion rate was 98.2% at 270°C under initial activity test conditions. After 24 hours of aging under the same anti-poisoning aging test conditions, the CO conversion rate was 93.6%.

[0079] Example 2

[0080] The aging-resistant, highly active CO oxidation catalyst of this embodiment comprises the following components by weight: 0.5% of an iridium-ruthenium alloy active component (with a mass ratio of iridium to ruthenium of 1:3), 88% of a tantalum-doped zirconium oxide support (with a molar ratio of zirconium to tantalum of 15:1), and 11.5% of a composite additive. The composite additive is a composite oxide of MoO3 and Nb2O5, with a mass ratio of MoO3 to Nb2O5 of 2:1.

[0081] The preparation method of the aging-resistant high-activity CO oxidation catalyst of this embodiment comprises the following steps:

[0082] S1 Support Preparation: Tantalum-doped zirconium oxide support was prepared by sol-gel combustion synthesis method, including the following steps:

[0083] (1) Dissolving metal salts: dissolve zirconium oxynitrate and TaCl5 in a molar ratio of 15:1 in deionized water and stir until transparent; add the combustion agent glycine and citric acid in a mass ratio of 1:3 to the above solution and continue stirring for 30 minutes; adjust the solution pH to 4 with dilute nitric acid to promote the complexation reaction and form a uniform sol; the combustion agent and Zr 4+ 、Ta 5+ The molar ratio of the total moles of is 2:1;

[0084] (2) Gelation and drying: The solution was placed in a 90°C water bath and continuously stirred to evaporate until it became a viscous gel; the solution was transferred to an oven and dried at 110°C for 12 h to obtain a porous xerogel precursor;

[0085] (3) Combustion synthesis: The porous xerogel precursor was ground into powder to ensure uniformity, and the powder was placed in a refractory crucible and heated to 300 °C in a muffle furnace at 5 °C / min to trigger a self-propagating combustion reaction;

[0086] (4) High-temperature calcination: Continue to raise the temperature to 700°C and keep it at this temperature for 3 hours to completely decompose the organic matter and obtain tantalum-doped zirconia crystals;

[0087] (5) Cooling and grinding: Cool naturally to room temperature and grind again to obtain a tantalum-doped zirconia carrier.

[0088] S2 carrier pretreatment: The tantalum-doped zirconia carrier was calcined by a gradient calcination method, firstly raised to 450°C at a rate of 8°C / min, kept warm for 2h, and then raised to 600°C at a rate of 5°C / min, kept warm for 3h.

[0089] S3 composite auxiliary agent impregnation, wherein the first impregnation loading MoO3 includes the following steps:

[0090] (1) Solution preparation: Prepare a 0.3 mol / L ammonium molybdate precursor solution with deionized water, add ammonium tartrate at a molar ratio of ammonium tartrate to Mo of 2:1, stir until completely dissolved, and adjust the solution pH to 5 with dilute nitric acid to inhibit the rapid hydrolysis of MoO3;

[0091] (2) Equal volume impregnation: the precursor solution is added dropwise to the tantalum-doped zirconia support until the pore volume is saturated;

[0092] (3) Static aging: Static aging for 10 h at room temperature in a sealed environment to promote uniform adsorption of Mo complexes;

[0093] (4) Drying and calcination: Dry at 70°C for 12 h to slowly remove moisture, then calcinate in a muffle furnace at 450°C for 5 h at a heating rate of 3°C / min to form a MoO3 crystalline phase;

[0094] The secondary impregnation loading of Nb2O5 includes the following steps:

[0095] 1) Solution preparation: Prepare a 0.1 mol / L ammonium niobium oxalate precursor solution using oxalic acid solution;

[0096] 2) Ultrasonic-assisted impregnation: The tantalum-doped zirconia support loaded with the MoO3 precursor was immersed in the niobium oxalate precursor solution and placed in a 50 kHz ultrasonic bath for 60 min;

[0097] 3) Microwave-enhanced drying: Drying was performed using microwave pulse mode, 40s on, 20s off, with a power of 500W, until completely dry;

[0098] 4) Decomposition and crystallization: Pre-calcine at 250℃ for 2h to decompose organic matter, then heat to 550℃ and calcine for 3h to form Nb2O5.

[0099] S4 Active Component Loading: The iridium-ruthenium alloy active component is loaded on a tantalum-doped zirconia support impregnated with a composite additive using a supercritical CO2 fluid deposition method to obtain an aging-resistant and highly active CO oxidation catalyst. The specific steps include:

[0100] (1) Preparation of iridium-ruthenium alloy precursor solution: iridium acetylacetonate and ruthenium acetylacetonate solutions were prepared with methanol, with the methanol ratio being 8 vol.%, and ultrasonically assisted dissolution (40 kHz, 30 min) was performed until the solution was clear and free of precipitation; the solution was filtered through a 0.25 μm organic filter membrane to remove undissolved impurities;

[0101] (2) Preactivation: The tantalum-doped zirconia support loaded with the composite additive was treated at 300 °C for 10 h in a H2 / N2 (5 vol.% H2) atmosphere to enhance the activity of the surface hydroxyl groups;

[0102] (3) Supercritical setting: Place the carrier in a reactor at 60°C, 13 MPa, and a CO2 flow rate of 2 L / min, introduce pure CO2 until the supercritical state is reached, and maintain for 30 min to exclude air;

[0103] (4) Precursor injection: Inject the iridium-ruthenium alloy precursor solution into the reactor through a high-pressure pump to ensure that CO2 and the precursor are fully mixed;

[0104] (5) Dynamic impregnation: Turn on magnetic stirring (600 rpm) and maintain supercritical conditions for 3 h to allow the precursor to be uniformly adsorbed in the pores of the support;

[0105] (6) Decompression deposition: Release the pressure (rate 0.3 MPa / min), CO2 gradually vaporizes, and the precursor is directionally deposited on the support surface;

[0106] (7) Hydrogen reduction: H2 / Ar mixed gas (H2 accounts for 8 vol.%) was introduced into a tube furnace, and the temperature was raised to 400℃ at 2℃ / min and kept at this temperature for 2h to make Ir 3+ 、Ru 3+ Reduce to a metallic state; further heat to 550°C and hold for 2 hours to promote alloying;

[0107] (8) In-situ alloying verification

[0108] XRD analysis: Detect whether the characteristic peaks of Ir-Ru alloy (such as face-centered cubic phase, 2θ≈40.5°, 47.2°) appear.

[0109] TEM-EDS scan: confirm the overlap between Ir and Ru element distributions (correlation coefficient > 0.9 is required).

[0110] The aging-resistant, highly active CO oxidation catalyst prepared in this example was used in a small-scale test to simulate the composition of steel sintering flue gas. Under the same test conditions as in Example 1, the CO conversion rate was measured to be 97.8% under the initial activity test conditions of 270°C, and the CO conversion rate after aging was 92.6%.

[0111] Example 3

[0112] The aging-resistant, highly active CO oxidation catalyst of this embodiment comprises the following components by weight: 1.5% of an iridium-ruthenium alloy active component (with a mass ratio of iridium to ruthenium of 1:5), 82% of a tantalum-doped zirconium oxide support (with a molar ratio of zirconium to tantalum of 19:1), and 16.5% of a composite additive. The composite additive is a composite oxide of MoO3 and Nb2O5, with a mass ratio of MoO3 to Nb2O5 of 3:1.

[0113] The preparation method of the aging-resistant high-activity CO oxidation catalyst of this embodiment comprises the following steps:

[0114] S1 Support Preparation: Tantalum-doped zirconium oxide support was prepared by sol-gel combustion synthesis method, including the following steps:

[0115] (1) Dissolving metal salts: dissolve zirconium oxynitrate and TaCl5 in a molar ratio of 19:1 in deionized water and stir until transparent; add the combustion agent glycine and citric acid in a mass ratio of 1:2 to the above solution and continue stirring for 30 minutes; adjust the solution pH to 3 with dilute nitric acid to promote the complexation reaction and form a uniform sol; the combustion agent and Zr 4+ 、Ta 5+ The molar ratio of the total moles of is 1.8:1;

[0116] (2) Gelation and drying: The solution was placed in a 90°C water bath and continuously stirred to evaporate until it became a viscous gel; the solution was transferred to an oven and dried at 110°C for 12 h to obtain a porous xerogel precursor;

[0117] (3) Combustion synthesis: The porous xerogel precursor was ground into powder to ensure uniformity, and the powder was placed in a refractory crucible and heated to 300 °C in a muffle furnace at 5 °C / min to trigger a self-propagating combustion reaction;

[0118] (4) High-temperature calcination: Continue to raise the temperature to 800°C and keep it for 2 hours to completely decompose the organic matter and obtain tantalum-doped zirconia crystals;

[0119] (5) Cooling and grinding: Cool naturally to room temperature and grind again to obtain a tantalum-doped zirconia carrier.

[0120] S2 carrier pretreatment: The tantalum-doped zirconia carrier was calcined by a gradient calcination method, firstly raised to 400°C at a rate of 10°C / min, kept warm for 2h, and then raised to 600°C at a rate of 5°C / min, kept warm for 3h.

[0121] S3 composite auxiliary agent impregnation, wherein the first impregnation loading MoO3 includes the following steps:

[0122] (1) Solution preparation: Prepare a 0.5 mol / L ammonium molybdate precursor solution with deionized water, add ammonium tartrate at a molar ratio of ammonium tartrate to Mo of 2:1, stir until completely dissolved, and adjust the solution pH to 5 with dilute nitric acid to inhibit the rapid hydrolysis of MoO3;

[0123] (2) Equal volume impregnation: the precursor solution is added dropwise to the tantalum-doped zirconia support until the pore volume is saturated;

[0124] (3) Static aging: Static aging for 12 h at room temperature in a sealed environment to promote uniform adsorption of Mo complexes;

[0125] (4) Drying and calcination: Dry at 80°C for 12 h to slowly remove moisture, then calcinate in a muffle furnace at 500°C for 5 h at a heating rate of 3°C / min to form a MoO3 crystal phase;

[0126] The secondary impregnation loading of Nb2O5 includes the following steps:

[0127] 1) Solution preparation: Prepare a 0.2 mol / L ammonium niobium oxalate precursor solution using oxalic acid solution;

[0128] 2) Ultrasonic-assisted impregnation: The tantalum-doped zirconia support loaded with the MoO3 precursor was immersed in the niobium oxalate precursor solution and placed in a 50 kHz ultrasonic bath for 60 min;

[0129] 3) Microwave-enhanced drying: Drying was performed using microwave pulse mode, 40s on, 15s off, at a power of 600W, until completely dry;

[0130] 4) Decomposition and crystallization: Pre-sinter at 250℃ for 3h to decompose organic matter, then heat to 550℃ and calcine for 4h to form Nb2O5.

[0131] S4 Active Component Loading: The iridium-ruthenium alloy active component is loaded on a tantalum-doped zirconia support impregnated with a composite additive using a supercritical CO2 fluid deposition method to obtain an aging-resistant and highly active CO oxidation catalyst. The specific steps include:

[0132] (1) Preparation of iridium-ruthenium alloy precursor solution: iridium acetylacetonate and ruthenium acetylacetonate solutions were prepared with methanol, with the methanol ratio being 10 vol.%, and ultrasonically assisted dissolution (40 kHz, 30 min) was performed until the solution was clear and free of precipitation; and filtered through a 0.25 μm organic filter membrane to remove undissolved impurities;

[0133] (2) Preactivation: The tantalum-doped zirconia support loaded with the composite additive was treated at 350 °C for 22 h in a H2 / N2 (5 vol.% H2) atmosphere to enhance the activity of the surface hydroxyl groups;

[0134] (3) Supercritical setting: Place the carrier in a reactor at 60°C, 12 MPa, and a CO2 flow rate of 2 L / min, introduce pure CO2 until the supercritical state is reached, and maintain for 30 min to exclude air;

[0135] (4) Precursor injection: Inject the iridium-ruthenium alloy precursor solution into the reactor through a high-pressure pump to ensure that CO2 and the precursor are fully mixed;

[0136] (5) Dynamic impregnation: Turn on magnetic stirring (800 rpm) and maintain supercritical conditions for 4 h to allow the precursor to be uniformly adsorbed in the pores of the support;

[0137] (6) Decompression deposition: Release the pressure (rate 0.5 MPa / min), CO2 gradually vaporizes, and the precursor is directionally deposited on the support surface;

[0138] (7) Hydrogen reduction: A H2 / Ar mixed gas (H2 accounts for 10 vol.%) was introduced into a tubular furnace, and the temperature was raised to 400°C at 2°C / min and kept at this temperature for 3 h to make Ir 3+ 、Ru 3+ Reduce to a metallic state; further heat to 550°C and hold for 2 hours to promote alloying;

[0139] (8) In-situ alloying verification

[0140] XRD analysis: Detect whether the characteristic peaks of Ir-Ru alloy (such as face-centered cubic phase, 2θ≈40.5°, 47.2°) appear.

[0141] TEM-EDS scan: confirm the overlap between Ir and Ru element distributions (correlation coefficient > 0.9 is required).

[0142] The aging-resistant, highly active CO oxidation catalyst prepared in this example was used in a small-scale test to simulate the composition of steel sintering flue gas. Under the same test conditions as in Example 1, the CO conversion rate was measured to be 98.5% under the initial activity test conditions of 280°C, and the CO conversion rate after aging was 95.6%.

[0143] Example 4

[0144] The aging-resistant, highly active CO oxidation catalyst of this embodiment comprises the following components by weight: 0.8% of an iridium-ruthenium alloy active component (with a mass ratio of iridium to ruthenium of 1:3), 87% of a tantalum-doped zirconia support (with a molar ratio of zirconium to tantalum of 16:1), and 12.2% of a composite additive. The composite additive is a composite oxide of MoO3 and Nb2O5, with a mass ratio of MoO3 to Nb2O5 of 2:1.

[0145] The preparation method of the aging-resistant high-activity CO oxidation catalyst of this embodiment comprises the following steps:

[0146] S1 Support Preparation: Tantalum-doped zirconium oxide support was prepared by sol-gel combustion synthesis method, including the following steps:

[0147] (1) Dissolving metal salts: dissolve zirconium oxynitrate and TaCl5 in a molar ratio of 16:1 in deionized water and stir until transparent; add the combustion agent glycine and citric acid in a mass ratio of 1:2 to the above solution and continue stirring for 30 minutes; adjust the solution pH to 4 with dilute nitric acid to promote the complexation reaction and form a uniform sol; the combustion agent and Zr 4+ 、Ta 5+ The molar ratio of the total moles of is 2:1;

[0148] (2) Gelation and drying: The solution was placed in an 80°C water bath and continuously stirred to evaporate until it became a viscous gel; the solution was transferred to an oven and dried at 105°C for 11 h to obtain a porous xerogel precursor;

[0149] (3) Combustion synthesis: The porous xerogel precursor was ground into powder to ensure uniformity, and the powder was placed in a refractory crucible and heated to 300 °C in a muffle furnace at 10 °C / min to trigger the self-propagating combustion reaction;

[0150] (4) High-temperature calcination: Continue to raise the temperature to 700°C and keep it at this temperature for 3 hours to completely decompose the organic matter and obtain tantalum-doped zirconia crystals;

[0151] (5) Cooling and grinding: Cool naturally to room temperature and grind again to obtain a tantalum-doped zirconia carrier.

[0152] S2 carrier pretreatment: The tantalum-doped zirconia carrier was calcined by a gradient calcination method, firstly increasing the temperature to 450°C at a rate of 10°C / min, keeping it warm for 1 hour, and then increasing it to 550°C at a rate of 3°C / min, keeping it warm for 3 hours.

[0153] S3 composite auxiliary agent impregnation, wherein the first impregnation loading MoO3 includes the following steps:

[0154] (1) Solution preparation: Prepare a 0.5 mol / L ammonium molybdate precursor solution with deionized water, add ammonium tartrate at a molar ratio of ammonium tartrate to Mo of 2:1, stir until completely dissolved, and adjust the solution pH to 3 with dilute nitric acid to inhibit the rapid hydrolysis of MoO3;

[0155] (2) Equal volume impregnation: the precursor solution is added dropwise to the tantalum-doped zirconia support until the pore volume is saturated;

[0156] (3) Static aging: Static aging for 6 h at room temperature in a sealed environment to promote uniform adsorption of Mo complexes;

[0157] (4) Drying and calcination: Dry at 80°C for 12 h to slowly remove moisture, then calcinate at 400°C in a muffle furnace for 4.5 h at a heating rate of 2°C / min to form a MoO3 crystalline phase;

[0158] The secondary impregnation loading of Nb2O5 includes the following steps:

[0159] 1) Solution preparation: Prepare an ammonium niobium oxalate precursor solution with a concentration of 0.05 mol / L using oxalic acid solution;

[0160] 2) Ultrasonic-assisted impregnation: The tantalum-doped zirconia support loaded with the MoO3 precursor was immersed in the niobium oxalate precursor solution and placed in a 45kHz ultrasonic bath for 30 minutes;

[0161] 3) Microwave-enhanced drying: Drying was performed using microwave pulse mode, 30s on and 20s off, with a power of 600W, until completely dry;

[0162] 4) Decomposition and crystallization: Pre-sinter at 250℃ for 3h to decompose organic matter, then heat to 450℃ and calcine for 4h to form Nb2O5.

[0163] S4 Active Component Loading: The iridium-ruthenium alloy active component is loaded on a tantalum-doped zirconia support impregnated with a composite additive using a supercritical CO2 fluid deposition method to obtain an aging-resistant and highly active CO oxidation catalyst. The specific steps include:

[0164] (1) Preparation of iridium-ruthenium alloy precursor solution: iridium acetylacetonate and ruthenium acetylacetonate solutions were prepared with methanol, with the methanol ratio being 10 vol.%, and ultrasonically assisted dissolution (40 kHz, 30 min) was performed until the solution was clear and free of precipitation; and filtered through a 0.25 μm organic filter membrane to remove undissolved impurities;

[0165] (2) Preactivation: The tantalum-doped zirconia support loaded with the composite additive was treated at 350°C for 20 h in a H2 / N2 (5 vol.% H2) atmosphere to enhance the activity of the surface hydroxyl groups;

[0166] (3) Supercritical setting: Place the carrier in a reactor at 50°C, 10 MPa, and a CO2 flow rate of 2 L / min, introduce pure CO2 until the supercritical state is reached, and maintain for 30 min to exclude air;

[0167] (4) Precursor injection: Inject the iridium-ruthenium alloy precursor solution into the reactor through a high-pressure pump to ensure that CO2 and the precursor are fully mixed;

[0168] (5) Dynamic impregnation: Turn on magnetic stirring (800 rpm) and maintain supercritical conditions for 2 h to allow the precursor to be uniformly adsorbed in the pores of the support;

[0169] (6) Decompression deposition: Release the pressure (rate 0.4 MPa / min), CO2 gradually vaporizes, and the precursor is directionally deposited on the support surface;

[0170] (7) Hydrogen reduction: H2 / Ar mixed gas (H2 accounts for 10 vol.%) was introduced into a tube furnace, and the temperature was raised to 350°C at 2°C / min and kept at this temperature for 3 h to make Ir 3+ 、Ru 3+ Reduce to a metallic state; further heat to 450°C and hold for 2 hours to promote alloying;

[0171] (8) In-situ alloying verification

[0172] XRD analysis: Detect whether the characteristic peaks of Ir-Ru alloy (such as face-centered cubic phase, 2θ≈40.5°, 47.2°) appear.

[0173] TEM-EDS scan: confirm the overlap between Ir and Ru element distributions (correlation coefficient > 0.9 is required).

[0174] The aging-resistant, highly active CO oxidation catalyst prepared in this example was used in a small-scale test to simulate the composition of steel sintering flue gas. Under the same test conditions as in Example 1, the CO conversion rate was measured to be 98% under the initial activity test conditions of 280°C, and the CO conversion rate after aging was 94.8%.

[0175] Example 5

[0176] The aging-resistant, highly active CO oxidation catalyst of this embodiment comprises the following components by weight: 1.2% of an iridium-ruthenium alloy active component (with a mass ratio of iridium to ruthenium of 1:3), 84% of a tantalum-doped zirconia support (with a molar ratio of zirconium to tantalum of 9:1), and 14.8% of a composite additive. The composite additive is a composite oxide of MoO3 and Nb2O5, with a mass ratio of MoO3 to Nb2O5 of 2:1.

[0177] The preparation method of the aging-resistant high-activity CO oxidation catalyst of this embodiment comprises the following steps:

[0178] S1 Support Preparation: Tantalum-doped zirconium oxide support was prepared by sol-gel combustion synthesis method, including the following steps:

[0179] (1) Dissolving metal salts: dissolve zirconium oxynitrate and TaCl5 in a molar ratio of 9:1 in deionized water and stir until transparent; add glycine and citric acid in a mass ratio of 1:2 to the above solution and continue stirring for 30 minutes; adjust the pH of the solution to 3 with dilute nitric acid to promote the complexation reaction and form a uniform sol; the combustible agent and Zr 4+ 、Ta 5+ The molar ratio of the total moles of is 1.5:1;

[0180] (2) Gelation and drying: The solution was placed in an 85°C water bath and continuously stirred to evaporate until it became a viscous gel; the solution was transferred to an oven and dried at 110°C for 10 h to obtain a porous xerogel precursor;

[0181] (3) Combustion synthesis: The porous xerogel precursor was ground into powder to ensure uniformity, and the powder was placed in a refractory crucible and heated to 300 °C in a muffle furnace at 5 °C / min to trigger a self-propagating combustion reaction;

[0182] (4) High-temperature calcination: Continue to raise the temperature to 800°C and keep it at this temperature for 3 hours to completely decompose the organic matter and obtain tantalum-doped zirconia crystals;

[0183] (5) Cooling and grinding: Cool naturally to room temperature and grind again to obtain a tantalum-doped zirconia carrier.

[0184] S2 carrier pretreatment: The tantalum-doped zirconia carrier was calcined by a gradient calcination method, firstly raised to 400°C at a rate of 5°C / min, kept warm for 1 hour, and then raised to 550°C at a rate of 4°C / min, kept warm for 2 hours.

[0185] S3 composite auxiliary agent impregnation, wherein the first impregnation loading MoO3 includes the following steps:

[0186] (1) Solution preparation: Prepare a 0.5 mol / L ammonium molybdate precursor solution with deionized water, add ammonium tartrate at a molar ratio of ammonium tartrate to Mo of 2:1, stir until completely dissolved, and adjust the solution pH to 5 with dilute nitric acid to inhibit the rapid hydrolysis of MoO3;

[0187] (2) Equal volume impregnation: the precursor solution is added dropwise to the tantalum-doped zirconia support until the pore volume is saturated;

[0188] (3) Static aging: Static aging for 6 h at room temperature in a sealed environment to promote uniform adsorption of Mo complexes;

[0189] (4) Drying and calcination: Dry at 80°C for 12 h to slowly remove moisture, then calcinate at 400°C in a muffle furnace for 4 h at a heating rate of 2°C / min to form a MoO3 crystalline phase;

[0190] The secondary impregnation loading of Nb2O5 includes the following steps:

[0191] 1) Solution preparation: Prepare a 0.2 mol / L ammonium niobium oxalate precursor solution using oxalic acid solution;

[0192] 2) Ultrasonic-assisted impregnation: The tantalum-doped zirconia support loaded with the MoO3 precursor was immersed in the niobium oxalate precursor solution and placed in a 50 kHz ultrasonic bath for 50 min;

[0193] 3) Microwave-enhanced drying: Drying was performed using microwave pulse mode, 40s on, 20s off, with a power of 500W, until completely dry;

[0194] 4) Decomposition and crystallization: Pre-calcine at 220℃ for 3h to decompose organic matter, then heat to 500℃ and calcine for 4h to form Nb2O5.

[0195] S4 Active Component Loading: The iridium-ruthenium alloy active component is loaded on a tantalum-doped zirconia support impregnated with a composite additive using a supercritical CO2 fluid deposition method to obtain an aging-resistant and highly active CO oxidation catalyst. The specific steps include:

[0196] (1) Preparation of iridium-ruthenium alloy precursor solution: iridium acetylacetonate and ruthenium acetylacetonate solutions were prepared with methanol, with the methanol ratio being 10 vol.%, and ultrasonically assisted dissolution (40 kHz, 30 min) was performed until the solution was clear and free of precipitation; and filtered through a 0.24 μm organic filter membrane to remove undissolved impurities;

[0197] (2) Preactivation: The tantalum-doped zirconia support loaded with the composite additive was treated at 350°C for 1 h in a H2 / N2 (5 vol.% H2) atmosphere to enhance the activity of the surface hydroxyl groups;

[0198] (3) Supercritical setting: Place the carrier in a reactor at 60°C, 10 MPa, and a CO2 flow rate of 1 L / min, introduce pure CO2 to a supercritical state, and maintain for 30 min to exclude air;

[0199] (4) Precursor injection: Inject the iridium-ruthenium alloy precursor solution into the reactor through a high-pressure pump to ensure that CO2 and the precursor are fully mixed;

[0200] (5) Dynamic impregnation: Turn on magnetic stirring (800 rpm) and maintain supercritical conditions for 4 h to allow the precursor to be uniformly adsorbed in the pores of the support;

[0201] (6) Decompression deposition: Release the pressure (rate 0.5 MPa / min), CO2 gradually vaporizes, and the precursor is directionally deposited on the support surface;

[0202] (7) Hydrogen reduction: A H2 / Ar mixed gas (H2 accounts for 10 vol.%) was introduced into a tubular furnace, and the temperature was raised to 400°C at 2°C / min and kept at this temperature for 3 h to make Ir 3+ 、Ru 3+ Reduce to metallic state; further heat to 500℃ and keep warm for 2h to promote alloying;

[0203] (8) In-situ alloying verification

[0204] XRD analysis: Detect whether the characteristic peaks of Ir-Ru alloy (such as face-centered cubic phase, 2θ≈40.5°, 47.2°) appear.

[0205] TEM-EDS scan: confirm the overlap between Ir and Ru element distributions (correlation coefficient > 0.9 is required).

[0206] The aging-resistant, highly active CO oxidation catalyst prepared in this example was used in a small-scale test to simulate the composition of steel sintering flue gas. Under the same test conditions as in Example 1, the CO conversion rate was measured to be 98.3% under the initial activity test conditions of 280°C, and the CO conversion rate after aging was 94.3%.

[0207] Comparative Example 1

[0208] The difference from Example 1 is that in the composite additive, the mass ratio of MoO3 to Nb2O5 is 5:1.

[0209] The CO oxidation catalyst prepared in Comparative Example 1 was used in a pilot test simulating the composition of steel sintering flue gas. Under the same testing conditions as Example 1, the CO conversion rate was 83.8% at 270°C for initial activity testing, and 70.6% after aging. This is because excessive Mo addition leads to excessive and strong acidic sites, resulting in excessive CO adsorption, NH3 enrichment, and increased side reactions, ultimately reducing catalytic efficiency and poisoning resistance.

[0210] Comparative Example 2

[0211] The difference from Example 1 is that in the composite additive, the mass ratio of MoO3 to Nb2O5 is 0.8:1.

[0212] The CO oxidation catalyst prepared in Comparative Example 2 was used in a pilot test simulating the composition of steel sintering flue gas. Under the same testing conditions as Example 1, the CO conversion rate was 76.9% at 270°C for initial activity testing, and 65.7% after aging. This is because the insufficient Mo content results in a lack of acidic sites in the catalyst, weakening its CO adsorption capacity and thus reducing the catalyst's activity.

[0213] Comparative Example 3

[0214] The difference from Example 1 is that the active component is pure iridium.

[0215] The CO oxidation catalyst prepared in Comparative Example 3 was used in a small test to simulate the composition of steel sintering flue gas. Under the same test conditions as Example 1, its CO conversion rate was measured to be 82.5% under the initial activity test conditions of 270°C, and the CO conversion rate after aging was 71.7%.

[0216] Comparative Example 4

[0217] The difference from Example 1 is that the active component is pure ruthenium.

[0218] The CO oxidation catalyst prepared in Comparative Example 4 was used in a small test to simulate the composition of steel sintering flue gas. Under the same test conditions as Example 1, its CO conversion rate was measured to be 75.8% under the initial activity test conditions of 270°C, and the CO conversion rate after aging was 62.3%.

[0219] Compared to Example 1, the catalyst performance of Comparative Examples 3-4 decreased. This is because the core of the electronic synergistic effect between Ir and Ru lies in optimizing the electronic state of active sites through charge transfer, energy band modulation, and interfacial coupling, weakening CO adsorption and preventing active site blockage; promoting O2 activation and providing sufficient active oxygen species; lowering the reaction energy barrier and accelerating CO→CO2 conversion; and enhancing stability and resisting poisoning and sintering. Therefore, the lack of Ru in Comparative Example 3 and Ir in Comparative Example 4 weakens the electronic synergistic effect between the active species, thereby reducing the catalyst's activity and resistance to poisoning.

[0220] Comparative Example 5

[0221] The difference from Example 1 is that a Pt / Pd active component (the mass ratio of Pt to Pd is 1:3) is used instead of the iridium-ruthenium alloy active component.

[0222] The CO oxidation catalyst prepared in Comparative Example 5 was used in a pilot test simulating the composition of steel sintering flue gas. Under the same testing conditions as in Example 1, the CO conversion rate was 82.7% at 270°C for initial activity testing, and 69.6% after aging. This is because Ir / Ru oxides can lower the reaction energy barrier through lattice oxygen participation, while Pt / Pd relies on a traditional adsorbate mechanism, resulting in a high reaction energy barrier and, consequently, low reactivity. Furthermore, the Ir / Ru surface is more inert: Pt / Pd is easily poisoned by small molecules such as NO and SO2, resulting in occupied surface active sites, while Ir / Ru has weaker binding energy for adsorbates and is more resistant to poisoning.

[0223] Comparative Example 6

[0224] The difference from Example 1 is that the carrier is a Ce-doped zirconia carrier.

[0225] The CO oxidation catalyst prepared in Comparative Example 6 was used in a small test to simulate the composition of steel sintering flue gas. Under the same test conditions as Example 1, its CO conversion rate was measured to be 73.2% under the initial activity test conditions of 270°C, and the CO conversion rate after aging was 63.6%.

[0226] The present invention develops a tantalum-doped zirconia carrier by Ta 5+ Inducing the generation of stable oxygen vacancies, thereby enhancing the catalyst's ability to activate oxygen, promoting the oxidation of SO2 to easily desorbed SO3, rather than forming stable sulfates, and reducing the poisoning of sulfur species on active sites. The oxygen storage and release capacity of CeO2 depends on Ce 3+ / Ce 4+ During the cycle, active oxygen accumulates on the surface and is easily combined with SO3 to form stable Ce2(SO4)3, which leads to catalyst poisoning.

[0227] Comparative Example 7

[0228] The difference from Example 1 is that MoO3 is not added to the composite auxiliary agent.

[0229] The CO oxidation catalyst prepared in Comparative Example 7 was used in a pilot test to simulate the composition of steel sintering flue gas. Under the same testing conditions as in Example 1, the CO conversion rate was 75.9% at 270°C for initial activity testing, and 60.9% after aging. This is because the absence of MoO₃ reduces the catalyst's acidic sites, weakening its ability to adsorb and activate CO, resulting in decreased catalyst activity and resistance to poisoning.

[0230] Comparative Example 8

[0231] The difference from Example 1 is that no Nb2O5 is added to the composite auxiliary agent.

[0232] The CO oxidation catalyst prepared in Comparative Example 8 was used in a pilot test simulating the composition of steel sintering flue gas. Under the same test conditions as Example 1, the CO conversion rate was 80.5% at 270°C for initial activity testing, and 68.7% after aging. This is due to a weakening of the synergistic effect of electrons, which reduces the catalyst's activity and poisoning resistance.

Claims

1. A aging-resistant and highly active CO oxidation catalyst, characterized in that: The invention comprises the following components in percentage by mass: 0.1-2% of an iridium-ruthenium alloy active component, 80-90% of a tantalum-doped zirconia carrier, and 10-20% of a composite auxiliary agent; the composite auxiliary agent is a composite oxide of MoO3 and Nb2O5, and the mass ratio of MoO3 to Nb2O5 is (1-3):

1.

2. The aging-resistant high-activity CO oxidation catalyst according to claim 1, characterized in that In the iridium-ruthenium alloy active component, the mass ratio of iridium to ruthenium is 1:(1-5).

3. The aging-resistant high-activity CO oxidation catalyst according to claim 1, characterized in that: In the tantalum-doped zirconia carrier, the molar ratio of zirconium to tantalum is (9-19):

1.

4. The method for preparing an aging-resistant high-activity CO oxidation catalyst according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1 Support Preparation: Tantalum-doped zirconia support was prepared by sol-gel combustion synthesis; S2 carrier pretreatment: calcining the tantalum-doped zirconia carrier by gradient calcination method, first raising the temperature to 400-450℃ at a rate of 5-10℃ / min, keeping it warm for 1-2h, then raising the temperature to 550-600℃ at a rate of 3-5℃ / min, keeping it warm for 2-3h; S3 composite additive impregnation: using ammonium tartrate as a complexing agent, MoO3 was loaded on the tantalum-doped zirconia support by the first impregnation, followed by a second impregnation using ultrasound-assisted microwave drying to load Nb2O5 on the tantalum-doped zirconia support; S4 active component loading: The iridium-ruthenium alloy active component is loaded on a tantalum-doped zirconia carrier impregnated with a composite additive using a supercritical CO2 fluid deposition method to obtain an aging-resistant and highly active CO oxidation catalyst.

5. The method for preparing an aging-resistant and highly active CO oxidation catalyst according to claim 4, wherein: In step S1, the sol-gel combustion synthesis method for preparing the tantalum-doped zirconia support includes the following steps: (1) Dissolving metal salts: dissolve zirconium oxynitrate and tantalum pentachloride in deionized water and stir until transparent; add combustion agent and continue stirring; adjust the solution pH to 3-4; (2) Gelation and drying: Place the solution in a water bath at 80-90°C and continue stirring to evaporate until it becomes a viscous gel; transfer to an oven for drying to obtain a porous xerogel precursor; (3) Combustion synthesis: The porous xerogel precursor is ground into powder, and the powder is placed in a muffle furnace and heated to 250-300°C at 5-10°C / min to trigger a self-propagating combustion reaction; (4) High temperature calcination: Continue to raise the temperature to 600-800°C and keep it at this temperature for 2-4 hours to completely decompose the organic matter and obtain tantalum-doped zirconia crystals; (5) Cooling and grinding: Cool naturally to room temperature and grind again to obtain a tantalum-doped zirconia carrier.

6. The method for preparing an aging-resistant and highly active CO oxidation catalyst according to claim 5, wherein: In step (1), the combustion agent is glycine and citric acid in a mass ratio of 1: (2-3); the combustion agent and Zr 4+ 、Ta 5+ The molar ratio of the total moles is (1.5-2):

1.

7. The method for preparing an aging-resistant and highly active CO oxidation catalyst according to claim 5, wherein: In step (2), the drying temperature is 100-110° C. and the drying time is 10-12 h.

8. The method for preparing an aging-resistant and highly active CO oxidation catalyst according to claim 4, wherein: In step S3, the first impregnation loading of MoO3 includes the following steps: (1) Solution preparation: Prepare a 0.1-0.5 mol / L ammonium molybdate precursor solution with deionized water, add ammonium tartrate at a molar ratio of ammonium tartrate to Mo of (1-2):1, stir until completely dissolved, and adjust the solution pH to 3-5; (2) Equal volume impregnation: the precursor solution is added dropwise to the tantalum-doped zirconia support until the pore volume is saturated; (3) Static aging: Static aging at room temperature in a sealed environment for 6-12 hours; (4) Drying and calcination: Dry at 60-80°C for 12 h, then calcinate in a muffle furnace at 400-500°C for 4-5 h at a heating rate of 2-3°C / min to form a MoO3 crystalline phase; The secondary impregnation loading of Nb2O5 includes the following steps: 1) Solution preparation: Prepare an ammonium niobium oxalate precursor solution with a concentration of 0.05-0.2 mol / L using oxalic acid solution; 2) Ultrasonic-assisted impregnation: The tantalum-doped zirconia support loaded with the MoO3 precursor was immersed in the niobium oxalate precursor solution and placed in a 40-50 kHz ultrasonic bath for 30-60 minutes; 3) Microwave-enhanced drying: Drying is carried out in microwave pulse mode, with a power of 300-600W, starting for 30-40s and stopping for 15-20s, until completely dried; 4) Decomposition and crystallization: pre-sinter at 200-250℃ for 2-3h, then heat to 450-550℃ and calcine for 3-4h.

9. The method for preparing an aging-resistant and highly active CO oxidation catalyst according to claim 4, wherein: In step S4, the supercritical CO2 fluid deposition method includes the following steps: (1) Preparation of iridium-ruthenium alloy precursor solution: prepare iridium acetylacetonate and ruthenium acetylacetonate solutions with methanol, with the methanol ratio being 5-10 vol.%; (2) Preactivation: Treat the tantalum-doped zirconia support loaded with the composite additive at 250-350°C for 1-22h in a H2 / N2 atmosphere; (3) Supercritical setting: Place the carrier in a reactor at 40-60°C, 10-15 MPa, and a CO2 flow rate of 0.5-2 L / min, introduce pure CO2 to a supercritical state, and maintain for 30 minutes to exclude air; (4) Precursor injection: Inject the iridium-ruthenium alloy precursor solution into the reactor to ensure that CO2 and the precursor are fully mixed; (5) Dynamic impregnation: Maintain supercritical conditions for 2-4 hours under stirring conditions to allow the precursor to be uniformly adsorbed into the pores of the support; (6) Decompression deposition: The pressure is released, CO2 gradually vaporizes, and the precursor is directionally deposited on the support surface; (7) Hydrogen reduction: Introduce H2 / Ar mixed gas into a tube furnace, raise the temperature to 300-400℃ at 2℃ / min, and keep it at this temperature for 2-3h to make Ir 3+ 、Ru 3+ Reduce to metallic state; further heat to 450-550℃ and keep warm for 1-2h to promote alloying.