Highly selective anti-coking co oxidation catalysts and methods for making same

Abstract

This invention provides a highly selective CO oxidation catalyst with resistance to carbon buildup and its preparation method. The CO oxidation catalyst includes a support, an active component supported on the surface and / or interior of the support, and an auxiliary agent; wherein the active component includes a noble metal element, and the auxiliary agent includes a non-noble metal element; based on 100% of the total mass of the support, the content of the auxiliary agent is less than 10%, preferably 3-6%; based on 100% of the total mass of the support and the auxiliary agent, the content of the active component is less than 1.5%, preferably 0.5-1.5%. The CO oxidation catalyst of this invention has the characteristics of resistance to NOx, resistance to carbon buildup, resistance to NO oxidation, and high CO catalytic combustion activity, exhibiting excellent performance in catalytic combustion of CO, especially in catalytic combustion of CO from iron and steel sintering flue gas.

Description

Technical Field

[0001] This invention relates to a highly selective catalyst for CO oxidation against carbon deposits and its preparation method, specifically to a catalyst for catalytic combustion of CO in steel sintering flue gas and its preparation method, belonging to the field of air pollution control technology. Background Technology

[0002] CO is one of the major air pollutants today. It is a colorless, odorless, and toxic gas that can directly endanger human health. Under sunlight, it can also combine with VOCs (volatile organic compounds) and NOx. x Photochemical reactions produce ozone, causing ozone pollution. As air pollution control efforts continue and ambient air quality improves, the requirements for CO emissions are becoming increasingly stringent. Iron and steel sintering flue gas contains a large amount of CO, with CO content generally ranging from 6000 to 10000 mg / Nm³. 3 Its governance has become a key issue of concern for steel companies worldwide.

[0003] Currently, due to the complex atmosphere of steel sintering flue gas and the lack of effective end-of-pipe treatment technologies, the main methods for reducing CO emissions from steel sintering flue gas are source control and process control. Even after source control and process control, the CO content in the sintering flue gas is still around 1000 mg / Nm³. 3 Therefore, developing efficient end-of-pipe control technologies is essential, as it can completely solve the problem of high CO emissions in the steel industry. Currently, end-of-pipe treatment technologies for CO emissions from steel sintering flue gas have become a research hotspot.

[0004] Catalytic combustion has attracted much attention due to its high removal rate, lack of secondary pollution, low energy consumption, high safety level of flameless oxidation, simple process, and wide applicability. It has become one of the main methods for controlling VOCs and CO emissions in many industries. The CO content in steel sintering flue gas is high, and catalytic combustion can release a large amount of heat, making it essential to fully utilize this heat. Placing a CO catalytic combustion device before the SCR denitrification device for steel sintering flue gas can provide a large amount of heat for the SCR denitrification reaction, effectively saving energy for enterprises.

[0005] However, the flue gas atmosphere in steel sintering is complex, containing a small amount of VOCs. The catalytic combustion of VOCs is far more difficult than that of CO. Under CO catalytic combustion conditions, unoxidized VOCs will deposit on the surface of the catalytic combustion catalyst, leading to catalyst deactivation due to carbon buildup over long periods. Furthermore, placing the CO catalytic combustion unit before the SCR denitrification unit in the steel sintering flue gas to provide supplemental heating for the SCR denitrification reaction will introduce NO into the CO catalytic combustion environment. x NO xThis will affect the catalytic combustion of CO, and at the same time, a large amount of NO will be oxidized into NO2, which will increase the difficulty of subsequent SCR denitrification.

[0006] Therefore, it is necessary to develop a NO-resistant x The development of highly active and selective CO oxidation catalysts that resist carbon buildup and are not prone to NO oxidation has become an urgent technical problem to be solved. Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In view of the technical problems existing in the prior art, the present invention first provides a highly selective CO oxidation catalyst with resistance to carbon deposition. The CO oxidation catalyst of the present invention has resistance to NO. x It has the characteristics of resisting carbon buildup, not easily oxidizing NO, and having high catalytic combustion activity for CO.

[0009] Furthermore, the present invention also provides a method for preparing a CO oxidation catalyst, which is simple and effective, uses readily available raw materials, is easy to operate, and can achieve mass production.

[0010] Furthermore, the CO oxidation catalyst of the present invention can be used in the catalytic combustion of CO-containing flue gas, especially in the catalytic combustion of CO in steel sintering flue gas.

[0011] Solution for solving the problem

[0012] [1] A CO oxidation catalyst, comprising a support, an active ingredient and an auxiliary agent supported on the surface and / or inside the support; wherein,

[0013] The active ingredient includes precious metal elements, and the auxiliary agent includes non-precious metal elements.

[0014] Based on the total mass of the carrier (100%), the content of the auxiliary agent is less than 10%, preferably 3-6%;

[0015] Based on the total mass of the carrier and the auxiliary agent (100%), the content of the active ingredient is less than 1.5%, preferably 0.5% to 1.5%.

[0016] [2] According to the CO oxidation catalyst described in [1] above, wherein the noble metal element includes platinum and / or palladium; and / or,

[0017] The carrier includes a cerium oxide carrier and / or an aluminum oxide carrier.

[0018] [3] The CO oxidation catalyst according to [1] or [2] above, wherein the auxiliary agent includes a first non-precious metal element and a second non-precious metal element, preferably, the mass ratio of the first non-precious metal element to the second non-precious metal element is 0.2 to 3:1.

[0019] [4] According to the CO oxidation catalyst described in [3] above, the first non-precious metal element includes magnesium and / or sodium, and the second non-precious metal element includes one or more combinations of vanadium, tungsten and molybdenum.

[0020] [5] The CO oxidation catalyst according to any one of [1]-[4] above, wherein the specific surface area of ​​the CO oxidation catalyst is 25 m². 2 / g or more, pore volume of 0.1cm 3 / g or more.

[0021] [6] A method for preparing a CO oxidation catalyst according to any one of [1]-[5] above, comprising the following steps:

[0022] The precursor of the auxiliary agent is dissolved in a solvent to obtain a precursor solution of the auxiliary agent;

[0023] The carrier is immersed in the precursor solution of the auxiliary agent once to obtain the first impregnation product;

[0024] The first impregnated product is dried once to obtain the first dried product;

[0025] The first dried product is subjected to a calcination treatment to obtain the first calcined product;

[0026] The active ingredient precursor is dissolved in a solvent to obtain an active ingredient precursor solution;

[0027] The first calcined product was impregnated a second time in the active ingredient precursor solution to obtain the second impregnated product;

[0028] The second impregnated product is subjected to a second drying process to obtain a second dried product;

[0029] The second dried product was subjected to a second calcination treatment to obtain a CO oxidation catalyst.

[0030] [7] According to the preparation method described in [6] above, wherein the auxiliary agent precursor includes one or more of magnesium salt, sodium salt, vanadium salt, tungsten salt and molybdenum salt; the active ingredient precursor includes one or more of platinum salt, rubidium salt, silver salt, ruthenium salt and palladium salt; and / or,

[0031] The primary impregnation and / or the secondary impregnation are equal-volume impregnations.

[0032] [8] According to the preparation method described in [6] or [7] above, the temperature of the primary drying treatment and / or the secondary drying treatment is 50 to 90°C, and the time of the primary drying treatment and / or the secondary drying treatment is 3 to 9 hours.

[0033] [9] The preparation method according to any one of [6]-[8] above, wherein the temperature of the first calcination treatment and / or the second calcination treatment is 500-700°C, and the time of the first calcination treatment and / or the second calcination treatment is 1-3h; preferably, the first calcination treatment and / or the second calcination treatment is carried out in an air atmosphere.

[0034]

[10] Use of a CO oxidation catalyst according to any one of [1]-[5] above in the catalytic combustion of CO, preferably in the catalytic combustion of CO in sintering flue gas of iron and steel.

[0035] The effects of the invention

[0036] The CO oxidation catalyst of the present invention has NO resistance x It features resistance to carbon buildup, resistance to oxidation of NO and CO, and high catalytic combustion activity, exhibiting excellent performance in catalytic combustion of CO, especially in catalytic combustion of CO in steel sintering flue gas.

[0037] Furthermore, the preparation method of the CO oxidation catalyst of the present invention is simple and effective, the raw materials are easy to obtain, the operation is convenient, and it can achieve mass production. Attached Figure Description

[0038] Figure 1 These are XRD comparison diagrams of the CO oxidation catalysts of Examples 1-3 of the present invention and the conventional industrial catalytic combustion catalysts of Comparative Examples 1 and 2.

[0039] Figure 2 This is a comparison diagram of toluene-TPD between the CO oxidation catalysts of Examples 1-3 of the present invention and the conventional industrial catalytic combustion catalysts of Comparative Examples 1 and 2.

[0040] Figure 3 The figures show the CO oxidation catalysts of Examples 1-3 and the conventional industrial catalytic combustion catalysts of Comparative Examples 1 and 2 of this invention, in the atmosphere of sintering flue gas from steelmaking, and their catalytic combustion performance.

[0041] Figure 4 The figures show the NO oxidation reaction performance of the CO oxidation catalysts of Examples 1-3 and the conventional industrial catalytic combustion catalysts of Comparative Examples 1 and 2 during the catalytic combustion of CO in the atmosphere of steel sintering flue gas.

[0042] Figure 5This is a transmission electron microscope (TEM) image of the CO oxidation catalyst of Example 1 of the present invention. Detailed Implementation

[0043] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0044] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0045] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0046] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0047] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0048] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0049] Unless otherwise stated, in this instruction manual, "more" in "multiple", "multi-variety", "multiple", etc., means a value of 2 or more.

[0050] In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes both the scenario in which the event occurs and the scenario in which the event does not occur.

[0051] <First Aspect>

[0052] A first aspect of the present invention provides a CO oxidation catalyst comprising a support, an active ingredient supported on the support, and an auxiliary agent; wherein,

[0053] The active ingredient includes precious metal elements, and the auxiliary agent includes non-precious metal elements.

[0054] Based on the total mass of the carrier (100%), the content of the active ingredient is 1.5% or less, preferably 0.5% to 1.5%; the content of the adjuvant is 10% or less, preferably 3% to 6%.

[0055] The CO oxidation catalyst of the present invention has NO resistance x It features resistance to carbon buildup, resistance to oxidation of NO and CO, and high catalytic combustion activity, exhibiting excellent performance in catalytic combustion of CO, especially in catalytic combustion of CO in steel sintering flue gas.

[0056] The CO oxidation catalyst of the present invention has a specific surface area of ​​25 m². 2 / g or more, pore volume of 0.1cm 3 / g or more. Due to the presence of additives, the specific surface area and pore volume of the CO oxidation catalyst will be reduced to some extent. Even with the reduction in specific surface area and pore volume, the present application still exhibits superior catalytic combustion performance of CO.

[0057] carrier

[0058] The support of this invention has a porous structure and a certain specific surface area. This invention does not particularly limit the support; it can be any support commonly used in the art, such as cerium oxide supports and / or aluminum oxide supports. Preferably, to better realize the function of the CO oxidation catalyst of this invention, a cerium oxide support is preferred. Cerium oxide supports possess unique oxygen storage and release properties and high-temperature rapid oxygen vacancy diffusion capabilities, enabling the CO oxidation catalyst of this invention to function more effectively. The cerium oxide support of this invention, with its excellent oxygen storage and release properties and… When used as a catalyst support, redox properties have shown unique advantages in the catalytic oxidation and combustion of CO.

[0059] Additives

[0060] In this invention, the additive includes a non-precious metal element. The inventors of this invention have discovered that by using a non-precious metal element as an additive, the NO conversion rate can be reduced, thereby obtaining an anti-NO agent. x A CO oxidation catalyst that resists carbon buildup and is not easily oxidized by NO.

[0061] In some specific embodiments, based on the total mass of the carrier (100%), the content of the additive is less than 10%, preferably 3-6%, for example: 1%, 2%, 3.5%, 4%, 4.5%, 5%, 5.5%, 7%, 8%, 9%, etc. When the content of the additive is less than 10%, it can effectively reduce the adsorption of VOCs and the oxidation of NO. However, if the content of the additive is too high, it may affect the catalytic oxidation combustion performance of CO.

[0062] In some specific embodiments, the present invention preferably uses two different non-precious metal elements. Specifically, the additive includes a first non-precious metal element and a second non-precious metal element. When the first non-precious metal element is used to modify the support, it can reduce the number of acidic sites on the catalyst surface, reduce the catalyst acidity, thereby reducing the catalyst's adsorption capacity for VOCs and giving the catalyst good anti-carbon deposition performance. When the second non-precious metal element is used to modify the support, it can promote the reaction of NO2 and CO to generate NO and CO2, thereby improving the catalyst's oxidation capacity for CO and improving macroscopic selectivity, that is, CO is completely oxidized while NO is not oxidized.

[0063] Furthermore, to maximize the effectiveness of the additive, in this invention, the mass ratio of the first non-precious metal element to the second non-precious metal element is 0.2 to 3:1. When the mass ratio of the first non-precious metal element to the second non-precious metal element is 0.2 to 3:1, both the first and second non-precious metal elements can effectively exert their effects, and they have a synergistic effect.

[0064] In some specific implementation schemes, considering that the roles of the first non-precious metal element and the second non-precious metal element can be effectively played, the first non-precious metal element includes magnesium and / or sodium, and the second non-precious metal element includes one or more combinations of vanadium, tungsten and molybdenum.

[0065] Active ingredients

[0066] The active ingredient of this invention includes a noble metal element. Noble metals have good catalytic activity; therefore, this invention enables the CO oxidation catalyst to achieve the catalytic combustion of CO by using a noble metal element.

[0067] In this invention, considering the cost of the active ingredient, the content of the active ingredient in the CO oxidation catalyst of this invention, based on the total mass of the support and the auxiliary agent as 100%, is less than 1.5%, preferably 0.5% to 1.5%, for example: 0.2%, 0.3%, 0.4%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, etc.; generally speaking, an active ingredient content of less than 1.5% can achieve excellent catalytic combustion performance of CO.

[0068] In some specific implementation schemes, considering that the role of the precious metal elements can be effectively played, the precious metal elements include platinum and / or palladium.

[0069] <Second aspect>

[0070] A second aspect of the present invention provides a method for preparing a CO oxidation catalyst according to the first aspect of the present invention, comprising the following steps:

[0071] The precursor of the auxiliary agent is dissolved in a solvent to obtain a precursor solution of the auxiliary agent;

[0072] The carrier is impregnated in the precursor solution of the auxiliary agent to obtain the first impregnation product;

[0073] The first impregnated product is dried once to obtain the first dried product;

[0074] The first dried product is subjected to a calcination treatment to obtain the first calcined product;

[0075] The active ingredient precursor is dissolved in a solvent to obtain an active ingredient precursor solution;

[0076] The first calcined product was impregnated in an active ingredient precursor solution to obtain a second impregnated product;

[0077] The second impregnated product is subjected to a second drying process to obtain a second dried product;

[0078] The second dried product was subjected to a second calcination treatment to obtain a CO oxidation catalyst.

[0079] The CO oxidation catalyst of the present invention has NO resistance x It features resistance to carbon buildup, resistance to oxidation of NO and CO, and high catalytic combustion activity, exhibiting excellent performance in catalytic combustion of CO, especially in catalytic combustion of CO in steel sintering flue gas.

[0080] Preparation of the first calcination product

[0081] The preparation method of this invention first dissolves the auxiliary agent precursor in a solvent to obtain an auxiliary agent precursor solution. In this invention, the auxiliary agent precursor may include one or more of magnesium salts, sodium salts, vanadium salts, tungsten salts, and molybdenum salts. Specifically, the magnesium salt may be one or more of magnesium nitrate, magnesium acetate, or magnesium chloride; the sodium salt may be one or more of sodium nitrate, sodium acetate, or sodium chloride; the vanadium salt may be ammonium metavanadate; the tungsten salt may be ammonium metatungstate; the molybdenum salt may be one or more of molybdenum nitrate, molybdenum acetate, or molybdenum chloride; and the platinum salt may be one or more of platinum nitrate, platinum acetate, or chloroplatinic acid.

[0082] In some specific embodiments, the auxiliary agent precursor includes a first auxiliary agent precursor and a second auxiliary agent precursor; the first auxiliary agent precursor includes a magnesium salt and / or a sodium salt, and the second auxiliary agent precursor includes one or more combinations of vanadium salt, tungsten salt and molybdenum salt.

[0083] The present invention does not particularly limit the solvent used to dissolve the precursor of the dissolving agent; it can be a solvent commonly used in the art, such as water.

[0084] The present invention does not impose any particular limitation on the concentration of the precursor solution of the auxiliary agent, which can generally be 1 to 3 mol / L, for example: 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, etc.

[0085] Next, the carrier is impregnated in the additive precursor solution to obtain the first impregnated product. For impregnation, the present invention preferably uses equal-volume impregnation. The equal-volume impregnation method generally involves determining the saturated water absorption capacity, i.e., water absorption rate, of the carrier before impregnation. Then, an equal volume of the desired additive precursor solution is prepared, and the carrier is impregnated in the additive precursor solution. The present invention does not particularly limit the method for determining the saturated water absorption capacity; it can be determined according to existing methods, or equal-volume impregnation can be performed according to the saturated water absorption capacity provided in the product instructions.

[0086] In this invention, the immersion time of the carrier in the auxiliary agent precursor solution is not particularly limited, as long as equal volume immersion is achieved. Generally, the immersion time in the auxiliary agent precursor solution can be 1-3 hours, for example: 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, etc.

[0087] Furthermore, the first impregnated product is subjected to a drying treatment to obtain a first dried product. This drying treatment removes the solvent physically adsorbed on the surface. Specifically, in this invention, the temperature of the first drying treatment is 50–90°C, for example: 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, etc.; the drying time is 3–9 hours, for example: 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0088] Furthermore, the first dried product is subjected to a calcination treatment to obtain a first calcined product. Through a single calcination treatment, the additives can be uniformly loaded in the form of oxides onto the surface and / or interior of the carrier.

[0089] Specifically, the temperature of the primary calcination treatment is 500–700℃, for example, 550℃, 600℃, 650℃, etc.; the duration of the primary calcination treatment is 1–3 hours, for example, 1.5 hours, 2 hours, 2.5 hours, etc. Preferably, the primary calcination treatment can be carried out in an air atmosphere. Specifically, the primary calcination treatment includes heating to 500–700℃ and calcining for 1–3 hours at a heating rate of 1–20℃ / min.

[0090] Preparation of CO oxidation catalysts

[0091] The active ingredient precursor is dissolved in a solvent to obtain an active ingredient precursor solution. In this invention, the active ingredient precursor includes one or more combinations of platinum salts, rubidium salts, silver salts, ruthenium salts, and palladium salts. The platinum salt can be one or more combinations of platinum nitrate, platinum acetate, chloroplatinic acid, etc. The rubidium salt can be one or more combinations of rubidium chloride, rubidium carbonate, rubidium sulfate, etc. The silver salt can be silver nitrate, etc. The ruthenium salt can be nitrosyl nitrate (IIl) solution, etc. The palladium salt can be one or more combinations of palladium nitrate, palladium acetate, palladium chloride, etc.

[0092] The present invention does not impose any particular limitation on the solvent used to dissolve the active ingredient precursor, and it can be a solvent commonly used in the art, such as water.

[0093] The present invention does not impose any particular limitation on the concentration of the precursor solution of the active ingredient, which can generally be 0.01 to 0.12 mol / L, for example: 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, etc.

[0094] Next, the first calcined product is impregnated in an active ingredient precursor solution to obtain a second impregnated product. Similarly, for impregnation, the present invention preferably uses the above-described equal-volume impregnation method.

[0095] In this invention, the impregnation time of the first calcined product in the active ingredient precursor solution is not particularly limited, as long as equal volume impregnation is achieved. Generally, the impregnation time in the auxiliary agent precursor solution can be 3-5 hours, for example: 3.2 hours, 3.5 hours, 3.8 hours, 4 hours, 4.2 hours, 4.5 hours, 4.8 hours, etc.

[0096] Furthermore, the second impregnated product is subjected to a secondary drying treatment to obtain a second dried product; by performing the drying treatment, the solvent physically adsorbed on the surface can be removed. Specifically, in this invention, the temperature of the secondary drying treatment is 50-90℃, for example: 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, etc.; the time of the secondary drying treatment is 3-9h, for example: 4h, 5h, 6h, 7h, 8h, etc.

[0097] Furthermore, the second dried product is subjected to a second calcination treatment to obtain a CO oxidation catalyst. Through calcination, the active components can be uniformly loaded in the form of oxides on the surface and / or inside the support.

[0098] Specifically, the temperature of the secondary calcination treatment is 500–700℃, for example, 550℃, 600℃, 650℃, etc.; the time of the secondary calcination treatment is 1–3 hours, for example, 1.5 hours, 2 hours, 2.5 hours, etc. Preferably, the secondary calcination treatment can be carried out in an air atmosphere. Specifically, the secondary calcination treatment includes heating to 500–700℃ and calcining for 1–3 hours at a heating rate of 1–20℃ / min.

[0099] <Third aspect>

[0100] A third aspect of the present invention provides the use of the CO oxidation catalyst according to the first aspect of the present invention in the catalytic combustion of CO, preferably in the catalytic combustion of CO in iron and steel sintering flue gas.

[0101] Example

[0102] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0103] Example 1

[0104] (1) Weigh 5.8g of sodium nitrate and 6.03g of ammonium metavanadate and dissolve them in 80mL of water. Stir to form the first impregnation solution. Then, put 100g of cerium oxide support into the first impregnation solution and stir continuously for 2 hours to obtain a wet cerium oxide support loaded with non-precious metal salt, i.e., the first impregnation product.

[0105] (2) The first impregnation product obtained in step (1) is dried at 60°C for 7 hours to obtain a dry cerium oxide carrier loaded with non-precious metal salts, i.e., the first dried product. Then, the first dried product is heated to 600°C at a heating rate of 2°C / min and calcined for 2 hours to obtain a cerium oxide carrier loaded with non-precious metals, i.e., the first calcined product. The sodium content is 1.5wt% and the alum content is 2.5wt% based on the total mass of the carrier (100%).

[0106] (3) Weigh 5.6g of platinum nitrate solution, wherein the platinum content of the platinum nitrate solution is 18.09wt%, dissolve it in 80mL of water, and stir to form a second impregnation solution. Then, put 100g of the first calcined product obtained in step (2) into the second impregnation solution and stir continuously for 4h to achieve equal volume impregnation, thereby obtaining the catalyst wet precursor loaded with noble metal salt, i.e., the second impregnation product.

[0107] (4) The second impregnation product obtained in step (3) is dried at 60°C for 7 hours to obtain a catalyst precursor loaded with noble metal salt, namely the second dried product. The second dried product is heated to 550°C at a heating rate of 2°C / min and calcined for 2 hours to obtain a CO oxidation catalyst, wherein the platinum content is 1 wt% based on the total mass of the first calcined product as 100%.

[0108] Example 2

[0109] (1) Weigh 19.42g of magnesium nitrate and 4.9g of ammonium metavanadate and dissolve them in 80mL of water. Stir to form the first impregnation solution. Then, put 100g of cerium oxide support into the first impregnation solution and stir continuously for 2 hours to achieve equal volume impregnation, and obtain cerium oxide wet support loaded with non-noble metal salt, i.e., the first impregnation product.

[0110] (2) The first impregnation product obtained in step (1) is dried at 70°C for 7 hours to obtain a dry cerium oxide carrier loaded with non-precious metal salts, namely the first dried product. Then, the first dried product is heated to 650°C at a heating rate of 5°C / min and calcined for 1.5 hours to obtain a cerium oxide carrier loaded with non-precious metals, namely the first calcined product, wherein, based on the total mass of the carrier as 100%, the content of metallic magnesium is 3wt% and the content of metallic alum is 2wt%.

[0111] (3) Weigh 5.6g of platinum nitrate solution, wherein the platinum content of the platinum nitrate solution is 18.09wt%, and dissolve it in 80mL of water, forming a second impregnation solution while stirring. Then, put 100g of the first calcined product obtained in step (2) into the second impregnation solution and stir continuously for 4h to achieve equal volume impregnation, thereby obtaining the catalyst wet precursor loaded with noble metal salt, i.e., the second impregnation product.

[0112] (4) The second impregnation product obtained in step (3) is dried at 60°C for 6.5 h to obtain a catalyst dry precursor loaded with noble metal salt, namely the second dried product. The second dried product is heated to 600°C at a heating rate of 5°C / min and calcined for 2 h to obtain a CO oxidation catalyst, wherein the platinum content is 1 wt% based on the total mass of the first calcined product as 100%.

[0113] Example 3

[0114] (1) Weigh 9.8g magnesium nitrate, 7.91g sodium nitrate, 2.46g ammonium metavanadate, and 2.05g ammonium metatungstate and dissolve them in 80mL of water, stirring to form the first impregnation solution. Then, 100g cerium oxide support is placed in the first impregnation solution and stirred continuously for 2 hours to achieve equal volume impregnation, resulting in a wet cerium oxide support loaded with non-noble metal salts, i.e., the first impregnation product.

[0115] (2) The first impregnation product obtained in step (1) is dried at 65°C for 9 hours to obtain a dry cerium oxide carrier loaded with non-precious metal salts, namely the first dried product. Then, the first dried product is heated to 650°C at a heating rate of 2°C / min and calcined for 2 hours to obtain a cerium oxide carrier loaded with non-precious metals, namely the first calcined product, wherein, based on the total mass of the carrier as 100%, the content of metallic magnesium is 1.5wt%, the content of metallic sodium is 2wt%, the content of metallic alum is 1wt%, and the content of metallic tungsten is 1.5wt%.

[0116] (3) Weigh 5.6g of platinum nitrate solution, wherein the platinum content of the platinum nitrate solution is 18.09wt%, dissolve it in 80mL of water, and form a second impregnation solution while stirring. Then, put 100g of the first calcined product obtained in step (2) into the second impregnation solution and stir continuously for 4h to achieve equal volume impregnation, thereby obtaining the catalyst wet precursor loaded with noble metal salt, i.e., the second impregnation product.

[0117] (4) The second impregnation product obtained in step (3) is dried at 65°C for 6 hours to obtain a catalyst precursor loaded with noble metal salt, namely the second dried product. The second dried product is heated to 550°C at a heating rate of 2°C / min and calcined for 3 hours to obtain a CO oxidation catalyst, wherein the platinum content is 1 wt% based on the total mass of the first calcined product as 100%.

[0118] Comparative Example 1

[0119] (1) Weigh 5.6g of platinum nitrate solution, wherein the platinum content of the platinum nitrate solution is 18.09wt%, and dissolve it in a certain amount of 80mL of water. Stirring the solution to form an impregnation solution. Then, a certain amount of 100g of cerium oxide support is added to the impregnation solution and stirred continuously for 4 hours to achieve equal volume impregnation, thereby obtaining a wet cerium oxide support loaded with noble metal salt, i.e., the impregnation product.

[0120] (2) The impregnation product obtained in step (1) is dried at 80°C for 9 hours to obtain a cerium oxide dry support loaded with noble metal salt, i.e., the dried product. The dried product is then heated to 600°C at a heating rate of 2°C / min and calcined for 3 hours to obtain a Pt / CeO2 catalytic combustion catalyst, wherein the platinum content is 1.5 wt% based on the total mass of the support (100%).

[0121] Comparative Example 2

[0122] (1) Weigh 5.6g of platinum nitrate solution, wherein the platinum content of the platinum nitrate solution is 18.09wt%, and dissolve it in 80mL of water to form an impregnation solution while stirring. Then, 100g of alumina support (γ-Al2O3) is added to the impregnation solution and impregnated for 4h with continuous stirring to achieve equal volume impregnation, thereby obtaining alumina wet support loaded with noble metal salt, i.e., the impregnation product.

[0123] (2) The impregnation product obtained in step (1) was dried at 80°C for 9 hours to obtain alumina dry support loaded with noble metal salt, i.e., the dried product. The dried product was then heated to 600°C at a heating rate of 2°C / min and calcined for 3 hours to obtain Pt / γ-Al2O3 catalytic combustion catalyst, wherein the platinum content was 1.5 wt% based on the total mass of the support (100%).

[0124] Performance testing

[0125] 1. XRD test

[0126] The CO oxidation catalysts of Examples 1-3 and the conventional industrial catalytic combustion catalysts of Comparative Examples 1-2 were analyzed using powder X-ray diffraction with CuK₂O₃ catalysts. α The radiation experiment conditions were analyzed, and the results are as follows: Figure 1 As shown.

[0127] Figure 1 These are the XRD patterns of the CO oxidation catalysts of Examples 1-3 and Comparative Examples 1-2 of the present invention, and conventional industrial catalytic combustion catalysts. Figure 1It can be seen that only the characteristic diffraction peaks of the cerium oxide and alumina support are present in the XRD patterns of each catalyst, indicating that the noble metal active component and the auxiliary component on the CO oxidation catalyst of this invention have good dispersibility.

[0128] 2. Toluene-TPD test

[0129] Under CO oxidation conditions in steel sintering flue gas, VOCs are not easily catalytically combusted and are ultimately adsorbed onto the catalyst, causing catalyst deactivation due to carbon buildup. The catalyst's ability to adsorb VOCs determines the amount of carbon buildup and the ease with which deactivation occurs. Toluene is the most difficult VOC component to catalytically combust and the most easily adsorbed onto the catalyst surface to form carbon deposits in steel sintering flue gas. Therefore, toluene was chosen to examine the VOCs adsorption capacity of various catalysts.

[0130] The CO oxidation catalysts of Examples 1-3 and the conventional industrial catalytic combustion catalysts (0.1 g) of Comparative Examples 1-2 were treated at 300°C for 1 h under nitrogen atmosphere at a flow rate of 100 ml / min (programmed temperature increase from 30°C to 300°C over 30 min). Then, they were treated at 50°C under a toluene and N2 mixture (1000 ppm toluene, nitrogen as the balance gas, programmed temperature increase from 30°C to 50°C over 10 min) at a gas flow rate of 100 ml / min. The mixture was then replaced with pure N2 at the same flow rate and maintained for 1 h to remove weakly adsorbed toluene. Under an N2 atmosphere, the temperature was programmed to increase from 50°C to 500°C at a heating rate of 10°C / min.

[0131] Figure 2 These are toluene-TPD diagrams of the CO oxidation catalysts of Examples 1-3 and Comparative Examples 1-2 of the present invention, and conventional industrial catalytic combustion catalysts. Figure 2 It can be seen that the CO oxidation catalyst of the present invention hardly adsorbs VOCs, while the conventional industrial catalytic combustion catalysts of Comparative Examples 1-2 have a strong ability to adsorb VOCs. The present invention successfully obtains a highly selective CO oxidation catalyst that does not adsorb VOCs and resists carbon deposition.

[0132] 3. Experiment on CO catalytic combustion in flue gas atmosphere of steel sintering

[0133] 0.1 g of the CO oxidation catalysts from Examples 1-3 and the conventional industrial catalytic combustion catalysts from Comparative Examples 1 and 2 were used in experiments. Specifically, the CO oxidation catalysts from Examples 1-3 and the conventional industrial catalytic combustion catalysts from Comparative Examples 1 and 2 were placed in fixed-bed reactors, respectively. The reaction gas was simulated flue gas from steel sintering, with a mass hourly space velocity (WHSV) of 60,000 mL / (g·h). The CO conversion rate and NO conversion rate of the catalysts at different reaction temperatures in the steel sintering flue gas atmosphere were tested. The CO conversion rate is the conversion rate of CO to CO2, and the NO conversion rate is the conversion rate of NO to NO2. The results are as follows: Figure 3 and Figure 4 As shown in Table 1, the simulated gas composition of the steel sintering flue gas is as described in Table 1.

[0134] Table 1

[0135] Components carbon monoxide Nitric oxide Nitrogen dioxide oxygen concentration 10000ppm 275ppm 30ppm 15％

[0136] Depend on Figure 3 It can be seen that the CO oxidation catalyst of the present invention catalyzes the combustion of CO in the atmosphere of iron and steel sintering flue gas. 90％ All were below 205℃, while the conventional industrial catalytic combustion catalysts of Comparative Examples 1 and 2 showed To values ​​for the catalytic combustion of CO in the atmosphere of steel sintering flue gas. 90％ The temperatures are approximately 265°C and 240°C, respectively.

[0137] Depend on Figure 4 It can be seen that the CO oxidation catalyst of the present invention hardly oxidizes NO when catalytically burning CO in the atmosphere of steel sintering flue gas, while the conventional industrial catalytic combustion catalysts of Comparative Examples 1 and 2 oxidize a large amount of NO when catalytically burning CO in the atmosphere of steel sintering flue gas.

[0138] And from Figure 2 , 3 and Figure 4 As can be seen from the above, the CO oxidation catalyst of the present invention is superior to conventional industrial catalytic combustion catalysts in terms of catalytic combustion of CO, non-oxidation of NO, and anti-carbon deposition in the atmosphere of iron and steel sintering flue gas. The preparation method of the present invention is simple, easy to implement, and convenient to operate.

[0139] 4. Specific surface area and pore volume test

[0140] The specific surface area and pore volume of the CO oxidation catalysts of Examples 1-3 and the conventional industrial catalytic combustion catalysts of Comparative Examples 1-2 were measured using a physical adsorption analyzer (McClair, Japan). The specific surface area was calculated using the Brunauer-Emmett-Teller (BET) method, and the pore volume was calculated using the non-local density functional theory (NLDFT) method. The results are shown in Table 2.

[0141] Table 2

[0142] CO oxidation catalyst <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> Example 1 30.1 0.14 Example 2 46.7 0.17 Example 3 32.1 0.15 Comparative Example 1 65.6 0.21 Comparative Example 2 153.3 0.25

[0143] As shown in Table 2, the presence of additives reduces the specific surface area and pore volume of the CO oxidation catalyst to some extent. Even with the reduced specific surface area and pore volume, the catalyst of this application still exhibits superior catalytic combustion performance for CO.

[0144] 5. Transmission electron microscopy (TEM) testing

[0145] Figure 5 A transmission electron microscope (TEM) image of the CO oxidation catalyst of Example 1 of the present invention is shown, as follows: Figure 5 It can be seen that the active ingredients and additives are highly dispersed on the surface of the catalyst support, and no large-sized nanoparticles of the active or additive components are observed.

[0146] Industrial availability

[0147] The CO oxidation catalyst provided by this invention can be industrially prepared and applied to the catalytic combustion of CO in steel sintering flue gas.

[0148] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0149] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A CO oxidation catalyst, characterized in that, Includes a carrier, active ingredients and adjuvants loaded on the surface and / or inside the carrier; wherein, The active ingredient includes precious metal elements, and the auxiliary agent includes non-precious metal elements. Based on the total mass of the carrier being 100%, the content of the auxiliary agent is less than 10%; Based on the total mass of the carrier and the auxiliaries being 100%, the content of the active ingredient is less than 1.5%; The carrier includes a cerium oxide carrier; the additives include a first non-precious metal element and a second non-precious metal element. The first non-precious metal element includes magnesium and / or sodium, and the second non-precious metal element includes one or more combinations of vanadium, tungsten and molybdenum.

2. The CO oxidation catalyst according to claim 1, characterized in that, Based on the total mass of the carrier being 100%, the content of the auxiliary agent is 3-6%; The content of the active ingredient is 0.5-1.5% based on the total mass of the carrier and the auxiliary agent as 100%.

3. The CO oxidation catalyst according to claim 1 or 2, characterized in that, The precious metal elements include platinum and / or palladium.

4. The CO oxidation catalyst according to claim 1 or 2, characterized in that, The mass ratio of the first non-precious metal element to the second non-precious metal element is 0.2~3:

1.

5. The CO oxidation catalyst according to claim 1 or 2, characterized in that, The specific surface area of ​​the CO oxidation catalyst is 25 m². 2 / g or more, pore volume of 0.1cm 3 / g or more.

6. A method for preparing a CO oxidation catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: The precursor of the auxiliary agent is dissolved in a solvent to obtain a precursor solution of the auxiliary agent; The carrier is immersed in the precursor solution of the auxiliary agent once to obtain the first impregnation product; The first impregnated product is dried once to obtain the first dried product; The first dried product is subjected to a calcination treatment to obtain the first calcined product; The active ingredient precursor is dissolved in a solvent to obtain an active ingredient precursor solution; The first calcined product was impregnated a second time in the active ingredient precursor solution to obtain the second impregnated product; The second impregnated product is subjected to a second drying process to obtain a second dried product; The second dried product was subjected to a second calcination treatment to obtain a CO oxidation catalyst.

7. The preparation method according to claim 6, characterized in that, The auxiliary precursor includes magnesium salts and / or sodium salts, as well as one or more combinations of vanadium salts, tungsten salts and molybdenum salts; The active ingredient precursor includes one or more of platinum salts, rubidium salts, silver salts, ruthenium salts, and palladium salts; and / or, The primary impregnation and / or the secondary impregnation are equal-volume impregnations.

8. The preparation method according to claim 6 or 7, characterized in that, The temperature of the primary drying process and / or the secondary drying process is 50~90℃, and the time of the primary drying process and / or the secondary drying process is 3-9h.

9. The preparation method according to claim 6 or 7, characterized in that, The temperature of the primary calcination treatment and / or the secondary calcination treatment is 500~700℃, and the time of the primary calcination treatment and / or the secondary calcination treatment is 1-3h.

10. The preparation method according to claim 9, characterized in that, The primary calcination treatment and / or the secondary calcination treatment are carried out in an air atmosphere.

11. Use of a CO oxidation catalyst according to any one of claims 1-5 in the catalytic combustion of CO.

12. The use according to claim 11, characterized in that, The CO oxidation catalyst is used in the catalytic combustion of CO in steel sintering flue gas.

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