A co oxidation catalyst, its preparation method and use

Abstract

The application relates to the technical field of catalysts, and discloses a CO oxidation catalyst, a preparation method and application thereof. The CO oxidation catalyst comprises a composite carrier and Nb2O5, K species and Pt species loaded on the composite carrier; the composite carrier comprises TiO2 and La2O3; and a Pt-O-K bond is formed between the K species and the Pt species. The CO oxidation catalyst has good sulfur resistance, good catalytic stability during long-time use, and high catalytic activity.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a CO oxidation catalyst, its preparation method, and its application. Background Technology

[0002] Catalytic oxidation technology is considered an effective method for removing CO from industrial flue gas due to its high efficiency and low secondary pollution. Pt-based catalysts are currently a commonly used CO oxidation catalyst; however, under actual long-term operation, impurities in the flue gas, such as SO2 and H2O, can cause irreversible deactivation of Pt-based catalysts. SO2 forms sulfates on the catalyst surface, altering the catalyst's chemical properties. Furthermore, the presence of H2O exacerbates SO2 poisoning on the catalyst surface, forming viscous H2SO4 that coats the catalyst surface. These factors lead to a sharp decline in catalyst performance. Therefore, developing highly active and stable CO catalysts for industrial flue gas has become a challenge.

[0003] To extend catalyst lifespan and reduce costs, researchers have developed acidic oxide doping methods, leveraging the acidic properties of SO2, to dope Pt-based catalysts with acidic oxides (such as WO3). These oxides attract the outermost electrons of Pt, suppressing electron pairing between SO2 and the Pt surface, thus inhibiting SO2 adsorption. However, the common practice of doping with acidic oxides before loading the active Pt component often leads to decreased catalytic activity. This is because commonly used CO catalysis supports (such as TiO2, ZrO2, and CeO2) provide the necessary oxygen for the reaction. Furthermore, the metal-support interaction (SMSI effect) between the active support and the active component plays a crucial role in controlling the valence state and electron transfer of the active component. Doping with acidic oxides interrupts this interaction, slowing down the CO oxidation rate on the active component. Therefore, conventional acidic oxide doping methods sacrifice catalytic activity for improved stability. Summary of the Invention

[0004] To address the aforementioned technical problem—that while doping with acidic oxides can improve the stability of Pt-based CO oxidation catalysts, it can also lead to a decrease in catalytic activity—this invention provides a CO oxidation catalyst, its preparation method, and its applications. This CO oxidation catalyst exhibits good resistance to sulfur (SO2), good catalytic stability during long-term use, and also possesses high catalytic activity.

[0005] The specific technical solution of this invention is as follows:

[0006] In a first aspect, the present invention provides a CO oxidation catalyst, comprising a composite support and Nb2O5, K species and Pt species supported on the composite support; the composite support comprises TiO2 and La2O3; and Pt-OK bonds are formed between the K species and the Pt species.

[0007] In this invention, by loading Nb2O5 into the catalyst, the outermost electrons of Pt can be attracted, thereby suppressing the electron pairing process between SO2 and the Pt surface, thus improving the catalyst's sulfur resistance and enabling the catalyst to have better catalytic stability when used for the oxidation treatment of CO in SO2-containing flue gas.

[0008] The introduction of Nb₂O₅ hinders the interaction between Pt and the active support TiO₂, leading to a decrease in catalytic activity. Therefore, this invention introduces the K species, which, after being doped into the catalyst, can form Pt-OK bonds with the Pt species, replacing the Pt-O-Ti bonding mode between Pt and the support. A strong metal-promoter interaction occurs between Pt and the K species. K acts as an electron promoter, modifying the electronic state of nearby Pt sites. During the formation of Pt-OK, electronegative O attracts electrons from Pt, and the electron-deficient Pt is ionic on the catalyst surface. In CO catalysis, the acquisition of active oxygen (O₂, hydroxyl groups) by the catalyst is a crucial step. The promoting effect of K species on O₂ adsorption on the catalyst is attributed to the independent s electrons in K's outermost shell, which, as electron donors, promote the adsorption of electron-acceptor gases (CO, O₂) on the catalyst surface. Furthermore, to maintain local charge balance, negatively charged hydroxyl groups (OH⁻ or...)... The K species are adsorbed on the surface of the positively charged groups formed by Pt and K. Therefore, the doping of K species can effectively stabilize the hydroxyl groups around Pt, providing the catalyst with the oxygen required for low-temperature oxidation, thereby reducing the catalyst's dependence on the active support TiO2 and solving the problem of decreased catalytic activity caused by Nb2O5 doping.

[0009] Furthermore, compared to Na, the K element used in this invention has a larger ionic radius, allowing for more effective dispersion within the catalyst. It also enhances the efficiency of the catalytic reaction by altering the electron density, resulting in better stability and activity of the catalyst at high temperatures or high SO2 concentrations. Moreover, K species can form stronger interactions between Pt and TiO2, particularly at high temperatures, helping to reduce Pt aggregation and maintain the dispersion of its active sites. This advantage may become more pronounced during long-term catalytic reactions.

[0010] Compared to other acidic oxides, this invention uses Nb₂O₅ to improve the sulfur resistance of the catalyst, offering the following advantages: Nb₂O₅ can form a stronger coordination structure with K species, further polarizing the hydroxyl groups on the oxide surface, thereby enhancing the activation ability of oxygen species. Simultaneously, Nb₂O₅ can more effectively stabilize Pt-OK bonds at low temperatures, thus improving the low-temperature activity of the catalyst.

[0011] Furthermore, by introducing La2O3 into the support to form a composite support, the present invention can further enhance the acidic environment, strengthen the electronic coupling of Pt-OK, and thus endow the CO oxidation catalyst with better catalytic activity and catalytic stability.

[0012] Preferably, the mass ratio of TiO2 to La2O3 is 8~10:1.

[0013] Preferably, the K species is a K oxide; the Pt species is a Pt oxide.

[0014] Secondly, the present invention provides a method for preparing the CO oxidation catalyst, comprising the following steps:

[0015] S1: K + After the solution is mixed with the composite carrier, it is dried and calcined.

[0016] S2: After mixing the product from step S1 with the Nb2O5 precursor solution, the mixture is dried and calcined.

[0017] S3: Combine the product from step S3 with Pt 2+ After the solutions are mixed, they are dried and calcined.

[0018] In the above preparation process, the sequence of first loading K species and then loading Nb₂O₅ yields the following effects: the pre-loaded K can form more uniform basic active sites on the support surface. These sites can form a stronger coordination structure during the subsequent dispersion of Nb₂O₅, thereby improving acidity and catalytic activity. Furthermore, alkali metal pretreatment may alter the hydroxyl distribution on the support surface, optimizing other potentially involved redox reaction pathways. Through these methods, the prepared catalyst can exhibit higher catalytic activity and maintain high activity even after prolonged use.

[0019] Preferably, in step S1, the composite carrier and K + The mass ratio is 10:0.07~0.10.

[0020] Preferably, in step S2, the mass ratio of the product from step S1 to the Nb element in the Nb2O5 precursor solution is 10:0.1~0.3.

[0021] Preferably, in step S3, the product of step S3 is reacted with Pt. 2+ The mass ratio is 1:0.03~0.08.

[0022] Preferably, in step S1, the K + The solution is a K2CO3 solution; in step S2, the Nb2O5 precursor is Nb(NO3)5; in step S3, the Pt 2+ The solution is a Pt(NO3)2 solution.

[0023] Preferably, in steps S1 to S3, the calcination is all aerobic calcination, with a temperature of 500 to 550°C and a time of 2 to 3 hours.

[0024] Thirdly, the present invention provides the application of the CO oxidation catalyst in the catalytic CO oxidation reaction.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) By loading Nb2O5 into the catalyst, the present invention can improve the catalyst’s resistance to sulfur (SO2). Furthermore, Nb2O5 can form a stronger coordination structure with K and more effectively stabilize the Pt-OK bond at low temperatures, thus improving the catalytic activity and catalytic stability to a greater extent.

[0027] (2) This invention solves the problem of decreased catalytic activity caused by the doping of acidic oxide Nb2O5 by loading K species into the catalyst. The larger ionic radius of K and its stronger interaction between Pt and TiO2 can be used to give the catalyst better catalytic activity and catalytic stability.

[0028] (3) By introducing La2O3 into the catalyst support, the present invention can enhance the electronic coupling of Pt-OK, thereby giving the catalyst better catalytic activity and catalytic stability.

[0029] (4) In the process of preparing the catalyst, the present invention adopts the order of first loading K species and then loading Nb2O5, which can further improve the catalytic activity and catalytic stability of the catalyst. Attached Figure Description

[0030] Figure 1 The results show the catalytic activity of the CO oxidation catalysts in Examples 1 and Comparative Examples 1-5.

[0031] Figure 2 The results show the catalytic stability test results of the CO oxidation catalysts in Example 1 and Comparative Examples 1-5.

[0032] Figure 3The results show the catalytic activity test results of the CO oxidation catalysts in Examples 1-3.

[0033] Figure 4 The results show the catalytic stability test results of the CO oxidation catalysts in Examples 1-3. Detailed Implementation

[0034] The present invention will be further described below with reference to embodiments.

[0035] General Implementation Examples

[0036] First, this invention relates to a CO oxidation catalyst, comprising a composite support and Nb₂O₅, K, and Pt species supported on the composite support; the composite support comprises TiO₂ and La₂O₃; and Pt-OK bonds are formed between the K and Pt species. In the above-mentioned CO oxidation catalyst, the synergistic effect of TiO₂, La₂O₃, Nb₂O₅, K, and Pt species enables the catalyst to exhibit high catalytic activity and good resistance to sulfur (SO₂), maintaining high catalytic activity even after long-term use in SO₂-containing flue gas.

[0037] In some specific embodiments, the mass ratio of TiO2 to La2O3 is 8~10:1.

[0038] In some specific embodiments, the K species is a K oxide; the Pt species is a Pt oxide.

[0039] Second, the present invention relates to a method for preparing the above-mentioned CO oxidation catalyst, the steps of which include:

[0040] S1: K + After the solution is mixed with the composite carrier, it is dried and calcined.

[0041] S2: After mixing the product from step S1 with the Nb2O5 precursor solution, the mixture is dried and calcined.

[0042] S3: Combine the product from step S3 with Pt 2+ After the solutions are mixed, they are dried and calcined.

[0043] In the above preparation method, by adopting the order of first loading K species and then loading Nb2O5, the catalytic activity and catalytic stability of the catalyst can be further improved.

[0044] In some specific embodiments, in step S1, the composite carrier and K + The mass ratio is 10:0.07~0.10.

[0045] In some specific embodiments, in step S2, the mass ratio of the product of step S1 to the Nb element in the Nb2O5 precursor solution is 10:0.1~0.3.

[0046] In some specific embodiments, in step S3, the product of step S3 is reacted with Pt 2+ The mass ratio is 1:0.03~0.08.

[0047] In some specific embodiments, in step S1, the K + The solution is a K2CO3 solution; in step S2, the Nb2O5 precursor is Nb(NO3)5; in step S3, the Pt 2+ The solution is a Pt(NO3)2 solution.

[0048] In some specific embodiments, in steps S1 to S3, the calcination is all aerobic calcination, with a temperature of 500 to 550°C and a time of 2 to 3 hours.

[0049] Third, the present invention relates to the application of the above-mentioned CO oxidation catalyst in the catalytic CO oxidation reaction.

[0050] In some specific embodiments, the temperature of the CO oxidation reaction is not lower than 95°C.

[0051] The present invention will now be described through specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0052] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used in this invention are conventional in the art and can be obtained through conventional commercial means; unless otherwise specified, the methods used in this invention are conventional methods in the art.

[0053] Example 1: Preparation of catalyst Pt-Nb2O5-K / TiO2-La2O3

[0054] The CO oxidation catalyst (Pt-Nb2O5-K / TiO2-La2O3) was prepared through the following steps:

[0055] S1: Loading K species

[0056] Under 70℃ water bath conditions, 0.14g of K2CO3 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of TiO2-La2O3 composite support (composed of TiO2 and La2O3 in a mass ratio of 9:1) was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 500℃ for 2 hours in air atmosphere to obtain K / TiO2-La2O3.

[0057] S2: Loaded with Nb2O5

[0058] Under 70℃ water bath conditions, 0.606g of Nb(NO3)5 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of K / TiO2-La2O3 prepared in step S1 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain Nb2O5-K / TiO2-La2O3.

[0059] S3: Pt-loaded species

[0060] Under 70℃ water bath conditions, 13.4 mL of 5 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of Nb2O5-K / TiO2-La2O3 prepared in step S2 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain the CO oxidation catalyst, denoted as "Pt-Nb2O5-K / TiO2-La2O3".

[0061] Example 2: Preparation of catalyst Pt-Nb2O5-K / TiO2-La2O3

[0062] The CO oxidation catalyst (Pt-Nb2O5-K / TiO2-La2O3) was prepared through the following steps:

[0063] S1: Loading K species

[0064] Under 70℃ water bath conditions, 0.13g of K2CO3 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of TiO2-La2O3 composite support (composed of TiO2 and La2O3 in a mass ratio of 8:1) was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 550℃ for 2 hours in air atmosphere to obtain K / TiO2-La2O3.

[0065] S2: Loaded with Nb2O5

[0066] Under 70℃ water bath conditions, 0.434g of Nb(NO3)5 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of K / TiO2-La2O3 prepared in step S1 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 550℃ for 2 hours in air atmosphere to obtain Nb2O5-K / TiO2-La2O3.

[0067] S3: Pt-loaded species

[0068] Under 70℃ water bath conditions, 15.5 mL of 10 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of Nb2O5-K / TiO2-La2O3 prepared in step S2 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder and placed in a muffle furnace for calcination at 550℃ for 2 hours in air atmosphere to obtain the CO oxidation catalyst, denoted as "Pt-Nb2O5-K / TiO2-La2O3".

[0069] Example 3: Preparation of catalyst Pt-Nb2O5-K / TiO2-La2O3

[0070] The CO oxidation catalyst (Pt-Nb2O5-K / TiO2-La2O3) was prepared through the following steps:

[0071] S1: Loading K species

[0072] Under 70℃ water bath conditions, 0.17g of K2CO3 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of TiO2-La2O3 composite support (composed of TiO2 and La2O3 in a mass ratio of 10:1) was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 500℃ for 3 hours in air atmosphere to obtain K / TiO2-La2O3.

[0073] S2: Loaded with Nb2O5

[0074] Under 70℃ water bath conditions, 1.301g of Nb(NO3)5 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of K / TiO2-La2O3 prepared in step S1 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and placed in a muffle furnace for calcination at 500℃ for 3 hours in air atmosphere to obtain Nb2O5-K / TiO2-La2O3.

[0075] S3: Pt-loaded species

[0076] Under 70℃ water bath conditions, 11.7 mL of 5 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of Nb2O5-K / TiO2-La2O3 prepared in step S2 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder and placed in a muffle furnace for calcination at 500℃ for 3 hours in air atmosphere to obtain the CO oxidation catalyst, denoted as "Pt-Nb2O5-K / TiO2-La2O3".

[0077] Comparative Example 1: Preparation of catalyst Pt-WO3-K / TiO2-La2O3

[0078] The only difference between this comparative example and Example 1 is that the type of acidic oxide in the catalyst of this comparative example has been changed, with Nb2O5 replaced by WO3. All other steps are the same as in Example 1.

[0079] Specifically, the CO oxidation catalyst (Pt-WO3-K / TiO2-La2O3) in this comparative example was prepared through the following steps:

[0080] S1: Loading K species

[0081] Under 70℃ water bath conditions, 0.14g of K2CO3 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of TiO2-La2O3 composite support (composed of TiO2 and La2O3 in a mass ratio of 9:1) was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 500℃ for 2 hours in air atmosphere to obtain K / TiO2-La2O3.

[0082] S2: Load WO3

[0083] Under 70℃ water bath conditions, add 0.24g of (NH4)6W7O to a beaker containing 100mL of deionized water. 24 After fully dissolving in 6H2O, add 10g of K / TiO2-La2O3 obtained in step S1 and stir until viscous. After drying in a 100℃ oven overnight to remove excess moisture, grind into powder, place in a muffle furnace, and calcine at 500℃ for 2 hours in air atmosphere to obtain WO3-K / TiO2-La2O3.

[0084] S3: Pt-loaded species

[0085] Under 70℃ water bath conditions, 13.4 mL of 5 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of WO3-K / TiO2-La2O3 prepared in step S2 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain the CO oxidation catalyst, denoted as "Pt-WO3-K / TiO2-La2O3".

[0086] Comparative Example 2: Preparation of catalyst Pt-K-Nb2O5 / TiO2-La2O3

[0087] The only difference between this comparative example and Example 1 is that the loading order of species K and Nb2O5 has been changed, with Nb2O5 being loaded first and then species K. All other steps are the same as in Example 1.

[0088] Specifically, the CO oxidation catalyst (Pt-K-Nb2O5 / TiO2-La2O3) in this comparative example was prepared through the following steps:

[0089] S1: Loaded with Nb2O5

[0090] Under 70℃ water bath conditions, 0.606g of Nb(NO3)5 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of TiO2-La2O3 composite support (composed of TiO2 and La2O3 in a mass ratio of 9:1) was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 500℃ for 2 hours in air atmosphere to obtain Nb2O5 / TiO2-La2O3.

[0091] S2: Loading K species

[0092] Under 70℃ water bath conditions, 0.14g of K2CO3 was added to a beaker containing 100mL of deionized water. After complete dissolution, 10g of Nb2O5 / TiO2-La2O3 prepared in step S2 was added, and the mixture was stirred until viscous. After removing excess moisture by placing the mixture in a 100℃ oven overnight, it was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain K-Nb2O5 / TiO2-La2O3.

[0093] S3: Pt-loaded species

[0094] Under 70℃ water bath conditions, 13.4 mL of 5 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of K-Nb2O5 / TiO2-La2O3 prepared in step S2 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder, placed in a muffle furnace, and calcined at 500℃ for 2 h in air atmosphere to obtain the CO oxidation catalyst, denoted as "Pt-K-Nb2O5 / TiO2-La2O3".

[0095] Comparative Example 3: Preparation of catalyst Pt-(Nb2O5-K) / TiO2-La2O3

[0096] The only difference between this comparative example and Example 1 is that the loading order of species K and Nb2O5 has been changed, and species K and Nb2O5 are loaded together on the support. All other steps are the same as in Example 1.

[0097] Specifically, the CO oxidation catalyst (Pt-(Nb2O5-K) / TiO2-La2O3) of this comparative example was prepared by the following steps:

[0098] S1: Loaded with K species and Nb2O5

[0099] Under 70℃ water bath conditions, 0.14g K2CO3 and 0.606g Nb(NO3)5 were added to a beaker containing 100mL deionized water and allowed to dissolve completely. Then, 10g of TiO2-La2O3 composite support (composed of TiO2 and La2O3 in a mass ratio of 9:1) was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 500℃ for 2 hours in air atmosphere to obtain (Nb2O5-K) / TiO2-La2O3.

[0100] S2: Pt-loaded species

[0101] Under 70℃ water bath conditions, 13.4 mL of 5 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of (Nb2O5-K) / TiO2-La2O3 prepared in step S1 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain the CO oxidation catalyst, denoted as "Pt-(Nb2O5-K) / TiO2-La2O3".

[0102] Comparative Example 4: Preparation of catalyst Pt-Nb2O5-K / TiO2

[0103] The only difference between this comparative example and Example 1 is that the support used in this comparative example is TiO2, which does not contain La2O3. All other steps are the same as in Example 1.

[0104] Specifically, the CO oxidation catalyst (Pt-Nb2O5-K / TiO2) of this comparative example was prepared through the following steps:

[0105] S1: Loading K species

[0106] Under 70℃ water bath conditions, 0.14g of K2CO3 was added to a beaker containing 100mL of deionized water and dissolved completely. Then, 10g of TiO2 support was added and stirred until viscous. After drying in a 100℃ oven overnight to remove excess moisture, the mixture was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain K / TiO2.

[0107] S2: Loaded with Nb2O5

[0108] Under 70℃ water bath conditions, 0.606g of Nb(NO3)5 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of K / TiO2 prepared in step S1 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain Nb2O5-K / TiO2.

[0109] S3: Pt-loaded species

[0110] Under 70℃ water bath conditions, 13.4 mL of 5 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of Nb2O5-K / TiO2 prepared in step S2 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain a CO oxidation catalyst, denoted as "Pt-Nb2O5-K / TiO2".

[0111] Comparative Example 5: Preparation of catalyst Pt-Nb2O5-Na / TiO2-La2O3

[0112] The only difference between this comparative example and Example 1 is that the K species in this comparative example is replaced with the Na species in the catalyst. All other steps are the same as in Example 1.

[0113] Specifically, the CO oxidation catalyst (Pt-Nb2O5-Na / TiO2-La2O3) in this comparative example was prepared through the following steps:

[0114] S1: Na-loaded species

[0115] Under 70℃ water bath conditions, 0.14g of Na2CO3 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of TiO2-La2O3 composite support (composed of TiO2 and La2O3 in a mass ratio of 9:1) was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and calcined in a muffle furnace at 500℃ for 2 hours in air atmosphere to obtain Na / TiO2-La2O3.

[0116] S2: Loaded with Nb2O5

[0117] Under 70℃ water bath conditions, 0.606g of Nb(NO3)5 was added to a beaker containing 100mL of deionized water and allowed to dissolve completely. Then, 10g of Na / TiO2-La2O3 prepared in step S1 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the mixture was ground into powder and placed in a muffle furnace for calcination at 500℃ for 2 hours in air atmosphere to obtain Nb2O5-Na / TiO2-La2O3.

[0118] S3: Pt-loaded species

[0119] Under 70℃ water bath conditions, 13.4 mL of 5 g / L Pt(NO3)2 solution was added to a beaker containing 100 mL of deionized water and stirred until homogeneous. Then, 9.95 g of Nb2O5-Na / TiO2-La2O3 prepared in step S2 was added and stirred until viscous. After removing excess moisture by placing in a 100℃ oven overnight, the solution was ground into powder, placed in a muffle furnace, and calcined at 500℃ for 2 h in air atmosphere to obtain a CO oxidation catalyst, denoted as "Pt-Nb2O5-Na / TiO2-La2O3".

[0120] Test Example: Catalytic Activity and Catalytic Stability Test

[0121] The CO oxidation catalysts prepared according to the methods in the various embodiments and comparative examples were used to catalyze the oxidation of CO in flue gas. The flue gas conditions (all component contents are volume fractions) were: CO 8000 ppm, O2 16%, N2 as balance gas, and space velocity 30000 h⁻¹. -1 The CO conversion rates measured at different temperatures are shown in the figure. Figure 1 and Figure 3 ( Figure 1 "Pt-Nb2O5-K / TiO2-La2O3" refers to the catalyst prepared according to the method in Example 1.

[0122] The CO oxidation catalysts prepared according to the methods in the various embodiments and comparative examples were used to catalyze the oxidation of CO in flue gas. The flue gas conditions (all component contents are volume fractions) were as follows: CO 8000 ppm, O2 16%, SO2 50 ppm, H2O 15%, N2 as the balance gas, temperature 170°C, and space velocity 30000 h⁻¹. -1 The CO conversion rates measured after continuous use for different periods are shown in the figure. Figure 2 and Figure 4 ( Figure 2 "Pt-Nb2O5-K / TiO2-La2O3" refers to the catalyst prepared according to the method in Example 1.

[0123] from Figures 1-4 From this, we can see that:

[0124] (1) Compared with the catalyst (Pt-WO3-K / TiO2-La2O3) in Comparative Example 1, the catalyst (Pt-Nb2O5-K / TiO2-La2O3) in Example 1 has higher catalytic activity and stability. The reason is presumably that Nb2O5 can form a stronger coordination structure with K species than WO3, further polarizing the hydroxyl groups on the oxide surface, thereby enhancing the activation ability of oxygen species; at the same time, Nb2O5 can also more effectively stabilize Pt-OK bonds at low temperatures, thereby improving the low-temperature activity of the catalyst.

[0125] (2) Compared with the catalysts of Comparative Example 2 (Pt-K-Nb2O5 / TiO2-La2O3) and Comparative Example 3 (Pt-(Nb2O5-K) / TiO2-La2O3), the catalyst of Example 1 has higher catalytic activity and stability. The reason is presumably that when the order of loading K species first and then Nb2O5 is adopted, the pre-loaded K can form more uniform basic active sites on the support surface. These sites can form a stronger coordination structure during the subsequent dispersion of Nb2O5, thereby improving acidity and catalytic activity. In addition, alkali metal pretreatment may change the hydroxyl distribution on the support surface and optimize other possible redox reaction pathways. However, when the loading order of K species and Nb2O5 is changed, or when both are loaded together, the above effects cannot be produced.

[0126] (3) Compared with the catalyst (Pt-Nb2O5-K / TiO2) in Comparative Example 4, the catalyst in Example 1 has higher catalytic activity and stability. The reason is speculated to be that, compared with using TiO2 alone as a support, introducing La2O3 into the support to form a composite support can further enhance the acidic environment, strengthen the electronic coupling of Pt-OK, and thus endow the CO oxidation catalyst with better catalytic activity and catalytic stability.

[0127] (4) Compared with the catalyst of Comparative Example 5 (Pt-Nb2O5-Na / TiO2-La2O3), the catalyst of Example 1 has higher catalytic activity and stability. The reason is speculated to be that: compared with Na, K has a larger ionic radius, which can be more effectively dispersed in the catalyst and improve the efficiency of the catalytic reaction by changing the electron density. This enables the catalyst to exhibit better stability and activity at high temperature or high SO2 concentration. In addition, K species can form stronger interactions between Pt and TiO2, especially under high temperature conditions, which helps to reduce the aggregation of Pt and thus maintain the dispersion of its active sites. This advantage may be more obvious in the long-term reaction of the catalyst.

[0128] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a CO oxidation catalyst, characterized in that the steps include... include: S1: K + After the solution is mixed with the composite carrier, it is dried and calcined. S2: After mixing the product from step S1 with the Nb2O5 precursor solution, the mixture is dried and calcined. S3: Combine the product from step S2 with Pt 2+ After mixing the solutions, the mixture is dried and calcined to obtain a CO oxidation catalyst comprising a composite support and Nb2O5, K species and Pt species supported on the composite support; the composite support comprises TiO2 and La2O3; and Pt-OK bonds are formed between the K species and Pt species.

2. The preparation method according to claim 1, characterized in that, The mass ratio of TiO2 to La2O3 is 8~10:

1.

3. The preparation method according to claim 1, characterized in that, The K species is a K oxide; the Pt species is a Pt oxide.

4. The preparation method according to claim 1, characterized in that, In step S1, the composite carrier and K + The mass ratio is 10:0.07~0.

10.

5. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of the product from step S1 to the Nb element in the Nb2O5 precursor solution is 10:0.1~0.

3.

6. The preparation method according to claim 1, characterized in that, In step S3, the product of step S2 and Pt 2+ The mass ratio is 1:0.03~0.

08.

7. The preparation method according to any one of claims 1 to 6, characterized in that, In step S1, the K + The solution is a K2CO3 solution; in step S2, the Nb2O5 precursor is Nb(NO3)5; in step S3, the Pt 2+ The solution is a Pt(NO3)2 solution.

8. The preparation method according to claim 1, characterized in that, In steps S1 to S3, the calcination is all aerobic calcination, with a temperature of 500 to 550°C and a time of 2 to 3 hours.

9. The application of the CO oxidation catalyst prepared by the preparation method according to any one of claims 1 to 8 in the catalytic CO oxidation reaction.

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