CO oxidation catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, and discloses a CO oxidation catalyst and a preparation method and application thereof. The CO oxidation catalyst comprises a composite carrier as well as Nb2O5, K species and Pt species which are loaded on the composite carrier, the composite carrier is prepared from TiO2 and La2O3; a Pt-O-K bond is formed between the K species and the Pt species. The CO oxidation catalyst provided by the invention has better sulfur resistance, has better catalytic stability in a long-time use process, and also has higher catalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a CO oxidation catalyst and a preparation method and application thereof. Background Art

[0002] Catalytic oxidation technology is considered to be 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, but during long-term operation under actual working conditions, impurities in the flue gas, such as SO2 and H2O, will cause irreversible deactivation of the Pt-based catalyst. SO2 will generate sulfate on the catalyst surface, changing the chemical properties of the catalyst. Not only that, the presence of H2O will aggravate the poisoning degree of SO2 on the catalyst surface, and generate viscous H2SO4 with SO2 to cover the catalyst surface. These factors will cause the performance of the catalyst to drop sharply. Therefore, it has become a challenge to develop highly active and highly stable CO catalysts for industrial flue gas.

[0003] In order to extend the service life of the catalyst as much as possible and reduce the cost of the catalyst, researchers doped acidic oxides (such as WO3) on the surface of Pt-based catalysts based on the acid properties of SO2, using acidic oxides to attract the outermost electrons of Pt, so that the electron pairing process between SO2 and the Pt surface is inhibited, thereby achieving the purpose of inhibiting the adsorption of SO2 on the catalyst surface. However, in the doping process, the acidic oxide is often doped in the carrier first, and then the active component Pt is loaded, which will result in a decrease in the catalytic activity of the catalyst. This is because: the commonly used carriers for CO catalysis are active carriers (such as TiO2, ZrO2, CeO2), in which the lattice oxygen provides the O required for the CO catalytic reaction; in addition, the metal-carrier interaction (SMSI effect) between the active carrier and the active component plays an important role in controlling the valence state of the active component and electron transfer; after doping with acidic oxides, the interaction between the active component and the carrier in the catalyst is interrupted, resulting in a slowdown in the CO oxidation reaction rate on the active component. Therefore, the conventional acidic oxide doping method improves catalytic stability at the expense of catalytic activity. Summary of the invention

[0004] In order to solve the above technical problem, that is, although doping with acidic oxides can improve the stability of Pt-based CO oxidation catalysts, it will cause a decrease in catalytic activity, the present invention provides a CO oxidation catalyst and a preparation method and application thereof. The CO oxidation catalyst has good sulfur (SO2) resistance, good catalytic stability during long-term use, and also has high catalytic activity.

[0005] The specific technical scheme of the present invention is: In a first aspect, the present invention provides a CO oxidation catalyst, comprising a composite carrier and Nb2O5, K species and Pt species loaded on the composite carrier; the composite carrier comprises TiO2 and La2O3; a Pt-OK bond is formed between the K species and the Pt species.

[0006] In the present invention, by loading Nb2O5 in the catalyst, the outermost electrons of Pt can be attracted, so that the electron pairing process between SO2 and the Pt surface is inhibited, thereby improving the sulfur resistance of the catalyst and enabling the catalyst to have better catalytic stability when used for the oxidation treatment of CO in flue gas containing SO2.

[0007] The introduction of Nb2O5 will hinder the interaction between Pt and the active carrier TiO2, thereby causing a decrease in catalytic activity. For this reason, the present invention introduces K species, which can form a Pt-OK bond with Pt species after being doped into the catalyst, replacing the Pt-O-Ti bonding mode between Pt and the carrier. A strong metal-promoter interaction can occur between Pt and K species. K, as an electron promoter, modifies the electronic state of the nearby Pt site. In the process of forming Pt-OK, the electronegative O attracts the electrons on Pt, and the electron-deficient Pt will be in the form of ions on the catalyst surface. In CO catalysis, the acquisition of active oxygen (O2, hydroxyl) by the catalyst is a very critical step in the reaction. The promotion of K species to the adsorption of O2 by the catalyst is attributed to the outermost independent s electrons of K. As an electron donor, it promotes the adsorption of electron acceptor gases (CO, O2) on the catalyst surface. In addition, in order to maintain local charge balance, negatively charged hydroxyl groups (OH- or OH*) 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 carrier TiO2, thereby solving the problem of decreased catalytic activity caused by Nb2O5 doping.

[0008] Moreover, compared with the Na element, the K element used in the present invention has a larger ionic radius, can be more effectively dispersed in the catalyst, and improve the efficiency of the catalytic reaction by changing the electron density, which can make the catalyst show better stability and activity at high temperature or high SO2 concentration. In addition, the K species can form a stronger interaction between Pt and TiO2, especially under high temperature conditions, which helps to reduce the aggregation of Pt, thereby maintaining the dispersion of its active sites. This advantage may be more obvious in the long-term reaction of the catalyst.

[0009] Compared with other acidic oxides, the present invention uses Nb2O5 to improve the sulfur resistance of the catalyst, which has the following advantages: Nb2O5 can form a stronger coordination structure with K species, further polarize the hydroxyl groups on the surface of the oxide, thereby enhancing the activation ability of oxygen species. At the same time, Nb2O5 can also more effectively stabilize the Pt-OK bond at low temperatures, thereby improving the low-temperature activity of the catalyst.

[0010] In addition, the present invention can further improve the acidic environment and strengthen the electronic coupling effect of Pt-OK by introducing La2O3 into the carrier to form a composite carrier, thereby giving the CO oxidation catalyst better catalytic activity and catalytic stability.

[0011] Preferably, the mass ratio of TiO2 to La2O3 is 8 to 10:1.

[0012] Preferably, the K species is K oxide; and the Pt species is Pt oxide.

[0013] In a second aspect, the present invention provides a method for preparing the CO oxidation catalyst, comprising the steps of: S1: K + After the solution is mixed with the composite support, it is dried and calcined; S2: mixing the product of step S1 with a Nb2O5 precursor solution, drying and calcining; S3: The product of step S3 is reacted with Pt 3+ After the solutions are mixed, they are dried and calcined.

[0014] In the above preparation process, the order of loading K species first and then loading Nb2O5 can produce the following effects: the pre-loaded K can form more uniform alkaline active sites on the carrier surface, and these sites can form stronger coordination structures in the subsequent dispersion process of Nb2O5, thereby improving acidity and catalytic activity. In addition, alkali metal pretreatment may change the distribution of hydroxyl groups on the carrier surface and optimize other possible redox reaction pathways. In this way, the prepared catalyst can have higher catalytic activity and maintain high activity after long-term use.

[0015] Preferably, in step S1, the composite carrier and K + The mass ratio is 10:0.07~0.10.

[0016] Preferably, 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.

[0017] Preferably, in step S3, the product of step S3 is reacted with Pt 3+ The mass ratio is 1:0.03~0.08.

[0018] Preferably, in step S1, the K + The solution is K2CO3 solution; in step S2, the Nb2O5 precursor is Nb(NO3)5; in step S3, the Pt 3+ The solution is Pt(NO3)3 solution.

[0019] Preferably, in steps S1 to S3, the calcination is oxygen calcination at a temperature of 500 to 550° C. and a time of 2 to 3 hours.

[0020] In a third aspect, the present invention provides use of the CO oxidation catalyst in catalyzing a CO oxidation reaction.

[0021] Compared with the prior art, the present invention has the following advantages: (1) The present invention can improve the sulfur (SO2) resistance of the catalyst by loading Nb2O5 in the catalyst. In addition, Nb2O5 can form a stronger coordination structure with K and more effectively stabilize the Pt-OK bond at low temperatures, thereby improving the catalytic activity and catalytic stability to a greater extent.

[0022] (2) The present invention solves the problem of decreased catalytic activity caused by doping of the acidic oxide Nb2O5 by loading K species in the catalyst. The larger ionic radius of K and the stronger interaction formed between Pt and TiO2 can be used to give the catalyst better catalytic activity and catalytic stability.

[0023] (3) The present invention can enhance the electronic coupling effect of Pt-OK by introducing La2O3 into the catalyst carrier, so that the catalyst has better catalytic activity and catalytic stability.

[0024] (4) In the process of preparing the catalyst, the present invention adopts the order of first loading the K species and then loading the Nb2O5, which can further improve the catalytic activity and catalytic stability of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The catalytic activity test results of the CO oxidation catalysts of Example 1 and Comparative Examples 1-5 are shown.

[0026] Figure 2 The catalytic stability test results of the CO oxidation catalysts of Example 1 and Comparative Examples 1-5 are shown.

[0027] Figure 3 The catalytic activity test results of the CO oxidation catalysts of Examples 1 to 3 are shown.

[0028] Figure 4 The catalytic stability test results of the CO oxidation catalysts of Examples 1 to 3 are shown. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments.

[0030] Overall embodiment First, the present invention relates to a CO oxidation catalyst, comprising a composite carrier and Nb2O5, K species and Pt species loaded on the composite carrier; the composite carrier comprises TiO2 and La2O3; a Pt-OK bond is formed between the K species and the Pt species. In the above CO oxidation catalyst, under the coordinated action of TiO2, La2O3, Nb2O5, K species and Pt species, the catalyst can have a higher catalytic activity and better sulfur (SO2) resistance, and can still maintain a higher catalytic activity after long-term use in flue gas containing SO2.

[0031] In some specific embodiments, the mass ratio of TiO2 to La2O3 is 8 to 10:1.

[0032] In some specific embodiments, the K species is K oxide; and the Pt species is Pt oxide.

[0033] Second, the present invention relates to a method for preparing the above-mentioned CO oxidation catalyst, the steps comprising: S1: K + After the solution is mixed with the composite support, it is dried and calcined; S2: mixing the product of step S1 with a Nb2O5 precursor solution, drying and calcining; S3: The product of step S3 is reacted with Pt 3+ After the solutions are mixed, they are dried and calcined.

[0034] 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.

[0035] In some specific embodiments, in step S1, the composite carrier and K + The mass ratio is 10:0.07~0.10.

[0036] 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.

[0037] In some specific embodiments, in step S3, the product of step S3 is reacted with Pt 3+ The mass ratio is 1:0.03~0.08.

[0038] In some specific embodiments, in step S1, the K+ The solution is K2CO3 solution; in step S2, the Nb2O5 precursor is Nb(NO3)5; in step S3, the Pt 3+ The solution is Pt(NO3)3 solution.

[0039] In some specific embodiments, in steps S1 to S3, the calcination is oxygen calcination at a temperature of 500 to 550° C. and a time of 2 to 3 hours.

[0040] Thirdly, the present invention relates to the use of the above CO oxidation catalyst in catalyzing CO oxidation reaction.

[0041] In some specific embodiments, the temperature of the CO oxidation reaction is not less than 95°C.

[0042] The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0043] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0044] Example 1: Preparation of catalyst Pt-Nb2O5-K / TiO2-La2O3 The CO oxidation catalyst (Pt-Nb2O5-K / TiO2-La2O3) was prepared by the following steps: S1: Loading K species Under 70℃ water bath conditions, add 0.14g K2CO3 to a beaker containing 100mL deionized water. After fully dissolving, add 10g TiO2-La2O3 composite carrier (composed of TiO2 and La2O3 with a mass ratio of 9:1) and stir until viscous. Place in a 100℃ oven overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in an air atmosphere to obtain K / TiO2-La2O3.

[0045] S2: Loaded Nb2O5 Under 70℃ water bath condition, add 0.606g Nb(NO3)5 to a beaker containing 100mL deionized water. After fully dissolving, add 10g K / TiO2-La2O3 prepared in step S1 and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, place in a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain Nb2O5-K / TiO2-La2O3.

[0046] S3: Loading Pt species Under 70℃ water bath condition, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g Nb2O5-K / TiO2-La2O3 prepared in step S2, stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-Nb2O5-K / TiO2-La2O3".

[0047] Example 2: Preparation of catalyst Pt-Nb2O5-K / TiO2-La2O3 The CO oxidation catalyst (Pt-Nb2O5-K / TiO2-La2O3) was prepared by the following steps: S1: Loading K species Under 70℃ water bath conditions, add 0.13g K2CO3 to a beaker containing 100mL deionized water. After fully dissolving, add 10g TiO2-La2O3 composite carrier (composed of TiO2 and La2O3 with a mass ratio of 8:1) and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 550℃ for 2h in an air atmosphere to obtain K / TiO2-La2O3.

[0048] S2: Loaded Nb2O5 Under 70℃ water bath condition, add 0.434g Nb(NO3)5 to a beaker containing 100mL deionized water. After fully dissolving, add 10g K / TiO2-La2O3 prepared in step S1 and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 550℃ for 2h in air atmosphere to obtain Nb2O5-K / TiO2-La2O3.

[0049] S3: Loading Pt species Under 70℃ water bath condition, add 15.5mL 10g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g Nb2O5-K / TiO2-La2O3 prepared in step S2, stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 550℃ for 2h in air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-Nb2O5-K / TiO2-La2O3".

[0050] Example 3: Preparation of catalyst Pt-Nb2O5-K / TiO2-La2O3 The CO oxidation catalyst (Pt-Nb2O5-K / TiO2-La2O3) was prepared by the following steps: S1: Loading K species Under 70℃ water bath conditions, add 0.17g K2CO3 to a beaker containing 100mL deionized water. After fully dissolving, add 10g TiO2-La2O3 composite carrier (composed of TiO2 and La2O3 with a mass ratio of 10:1) and stir until viscous. Place in an oven at 100℃ for one night to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 3h in air atmosphere to obtain K / TiO2-La2O3.

[0051] S2: Loaded Nb2O5 Under 70℃ water bath condition, add 1.301g Nb(NO3)5 to a beaker containing 100mL deionized water. After fully dissolving, add 10g K / TiO2-La2O3 prepared in step S1 and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 3h in air atmosphere to obtain Nb2O5-K / TiO2-La2O3.

[0052] S3: Loading Pt species Under 70℃ water bath condition, add 11.7mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g Nb2O5-K / TiO2-La2O3 prepared in step S2, stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 3h in air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-Nb2O5-K / TiO2-La2O3".

[0053] Comparative Example 1: Preparation of Catalyst Pt-WO3-K / TiO2-La2O3 The difference between this comparative example and Example 1 is that the type of acidic oxide in the catalyst of this comparative example is changed, and Nb2O5 is replaced by WO3. The remaining steps are the same as those of Example 1.

[0054] Specifically, the CO oxidation catalyst (Pt-WO3-K / TiO2-La2O3) of this comparative example was prepared by the following steps: S1: Loading K species Under 70℃ water bath conditions, add 0.14g K2CO3 to a beaker containing 100mL deionized water. After fully dissolving, add 10g TiO2-La2O3 composite carrier (composed of TiO2 and La2O3 with a mass ratio of 9:1) and stir until viscous. Place in a 100℃ oven overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in an air atmosphere to obtain K / TiO2-La2O3.

[0055] S2: Load WO3 In a 70℃ water bath, add 0.24g (NH4)6W7O to a beaker containing 100mL of deionized water. 24 ·6H2O, after fully dissolved, add 10g of K / TiO2-La2O3 prepared in step S1, stir until viscous. Place in an oven at 100℃ for one night to remove excess water, grind into powder, place in a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain WO3-K / TiO2-La2O3.

[0056] S3: Loading Pt species Under 70℃ water bath conditions, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g WO3-K / TiO2-La2O3 prepared in step S2, and stir until viscous. After being placed in an oven at 100℃ for one night to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in an air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-WO3-K / TiO2-La2O3".

[0057] Comparative Example 2: Preparation of Catalyst Pt-K-Nb2O5 / TiO2-La2O3 The difference between this comparative example and Example 1 is that this comparative example changes the loading order of K species and Nb2O5, and changes to loading Nb2O5 first and then loading K species. The remaining steps are the same as Example 1.

[0058] Specifically, the CO oxidation catalyst (Pt-K-Nb2O5 / TiO2-La2O3) of this comparative example was prepared by the following steps: S1: Loading Nb2O5 Under 70℃ water bath conditions, add 0.606g Nb(NO3)5 to a beaker containing 100mL deionized water. After fully dissolving, add 10g TiO2-La2O3 composite carrier (composed of TiO2 and La2O3 with a mass ratio of 9:1) and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in an air atmosphere to obtain Nb2O5 / TiO2-La2O3.

[0059] S2: Loading K species Under 70℃ water bath condition, add 0.14g K2CO3 to a beaker containing 100mL deionized water. After fully dissolving, add 10g Nb2O5 / TiO2-La2O3 prepared in step S2 and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain K-Nb2O5 / TiO2-La2O3.

[0060] S3: Loading Pt species Under 70℃ water bath condition, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g K-Nb2O5 / TiO2-La2O3 prepared in step S2, stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-K-Nb2O5 / TiO2-La2O3".

[0061] Comparative Example 3: Preparation of Catalyst Pt-(Nb2O5-K) / TiO2-La2O3 The difference between this comparative example and Example 1 is that this comparative example changes the loading order of K species and Nb2O5, and loads K species and Nb2O5 onto the carrier together. The remaining steps are the same as Example 1.

[0062] Specifically, the CO oxidation catalyst (Pt-(Nb2O5-K) / TiO2-La2O3) of this comparative example was prepared by the following steps: S1: Loading K species and Nb2O5 Under 70℃ water bath conditions, add 0.14g K2CO3 and 0.606g Nb(NO3)5 to a beaker containing 100mL deionized water. After fully dissolving, add 10g TiO2-La2O3 composite carrier (composed of TiO2 and La2O3 with a mass ratio of 9:1) and stir until viscous. Place in an oven at 100℃ for one night to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain (Nb2O5-K) / TiO2-La2O3.

[0063] S2: Loaded Pt species Under 70℃ water bath condition, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g (Nb2O5-K) / TiO2-La2O3 prepared in step S1, stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-(Nb2O5-K) / TiO2-La2O3".

[0064] Comparative Example 4: Preparation of Catalyst Pt-Nb2O5-K / TiO2 The difference between this comparative example and Example 1 is that the carrier used in this comparative example is TiO2, which does not contain La2O3. The remaining steps are the same as those in Example 1.

[0065] Specifically, the CO oxidation catalyst (Pt-Nb2O5-K / TiO2) of this comparative example was prepared by the following steps: S1: Loading K species Under 70℃ water bath condition, add 0.14g K2CO3 to a beaker containing 100mL deionized water. After fully dissolving, add 10g TiO2 carrier and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain K / TiO2.

[0066] S2: Loaded Nb2O5 Under 70℃ water bath condition, add 0.606g Nb(NO3)5 to a beaker containing 100mL deionized water. After fully dissolving, add 10g K / TiO2 prepared in step S1 and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, place in a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain Nb2O5-K / TiO2.

[0067] S3: Loading Pt species Under 70℃ water bath condition, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g Nb2O5-K / TiO2 prepared in step S2, stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-Nb2O5-K / TiO2".

[0068] Comparative Example 5: Preparation of Catalyst Pt-Nb2O5-Na / TiO2-La2O3 The difference between this comparative example and Example 1 is that in the catalyst of this comparative example, the K species is replaced by the Na species. The remaining steps are the same as those of Example 1.

[0069] Specifically, the CO oxidation catalyst (Pt-Nb2O5-Na / TiO2-La2O3) of this comparative example was prepared by the following steps: S1: Loading Na species Under a 70°C water bath, add 0.14g Na2CO3 to a beaker containing 100mL deionized water, and after fully dissolving, add 10g TiO2-La2O3 composite carrier (composed of TiO2 and La2O3 with a mass ratio of 9:1), and stir until viscous. After being placed in an oven at 100°C for one night to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500°C for 2h in an air atmosphere to obtain Na / TiO2-La2O3.

[0070] S2: Loaded Nb2O5 Under 70℃ water bath condition, add 0.606g Nb(NO3)5 to a beaker containing 100mL deionized water. After fully dissolving, add 10g Na / TiO2-La2O3 prepared in step S1 and stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, place in a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain Nb2O5-Na / TiO2-La2O3.

[0071] S3: Loading Pt species Under 70℃ water bath condition, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then add 9.95g Nb2O5-Na / TiO2-La2O3 prepared in step S2, stir until viscous. Place in an oven at 100℃ overnight to remove excess water, grind into powder, put into a muffle furnace, and calcine at 500℃ for 2h in air atmosphere to obtain a CO oxidation catalyst, recorded as "Pt-Nb2O5-Na / TiO2-La2O3".

[0072] Test example: Catalytic activity and catalytic stability test The CO oxidation catalyst prepared according to the methods in the embodiments and comparative examples was used to catalyze the oxidation of CO in flue gas. The flue gas conditions (the following component contents are all volume fractions) were: CO 8000ppm, O2 16%, N2 as the balance gas, and the space velocity was 30000h -1 The CO conversion rates measured at different temperatures are shown in Figure 1 and Figure 3 ( Figure 1 "Pt-Nb2O5-K / TiO2-La2O3" refers to the catalyst prepared according to the method of Example 1).

[0073] The CO oxidation catalyst prepared according to the methods in the embodiments and comparative examples was used to catalyze the oxidation of CO in flue gas. The flue gas conditions (the following component contents are all volume fractions) were: CO 8000ppm, O2 16%, SO2 50ppm, H2O 15%, N2 as the balance gas, the temperature was 170°C, the air velocity was 30000h -1 After continuous use for different time periods, the measured CO conversion rates are shown in Figure 2 and Figure 4 ( Figure 2 "Pt-Nb2O5-K / TiO2-La2O3" refers to the catalyst prepared according to the method of Example 1).

[0074] from Figures 1 to 4 It can be seen that: (1) Compared with the catalyst of Comparative Example 1 (Pt-WO3-K / TiO2-La2O3), the catalyst of Example 1 (Pt-Nb2O5-K / TiO2-La2O3) has higher catalytic activity and stability. The reason is presumed to be that: compared with WO3, Nb2O5 can form a stronger coordination structure with K species, further polarize the surface hydroxyl groups of the oxide, thereby enhancing the activation ability of oxygen species; at the same time, Nb2O5 can also more effectively stabilize the Pt-OK bond at low temperature, thereby improving the low-temperature activity of the catalyst.

[0075] (2) Compared with the catalyst of comparative example 2 (Pt-K-Nb2O5 / TiO2-La2O3) and the catalyst of comparative example 3 (Pt-(Nb2O5-K) / TiO2-La2O3), the catalyst of Example 1 has higher catalytic activity and stability. The reason is presumed to be that when the order of loading K species first and then loading Nb2O5 is adopted, the pre-loaded K can form more uniform alkaline active sites on the carrier surface, and these sites can form stronger coordination structures in the subsequent dispersion process of Nb2O5, thereby improving acidity and catalytic activity. In addition, alkali metal pretreatment may change the distribution of hydroxyl groups on the carrier surface and optimize other possible redox reaction pathways. However, when the loading order of K species and Nb2O5 is changed, or the two are loaded together, the above effect cannot be produced.

[0076] (3) Compared with the catalyst (Pt-Nb2O5-K / TiO2) of Comparative Example 4, the catalyst of Example 1 has higher catalytic activity and stability. The reason is presumed to be that, compared with using TiO2 alone as a carrier, the introduction of La2O3 into the carrier to form a composite carrier can further improve the acidic environment, strengthen the electronic coupling effect of Pt-OK, and thus give the CO oxidation catalyst better catalytic activity and catalytic stability.

[0077] (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 presumed to be that: compared with the Na element, the K element has a larger ionic radius, can be more effectively dispersed in the catalyst, and improve the efficiency of the catalytic reaction by changing the electron density, which can make the catalyst show better stability and activity at high temperature or high SO2 concentration; and the K species can form a stronger interaction between Pt and TiO2, especially under high temperature conditions, which helps to reduce the aggregation of Pt, thereby maintaining the dispersion of its active sites. This advantage may be more obvious in the long-term reaction of the catalyst.

[0078] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A CO oxidation catalyst, characterized in that It 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-OK bond is formed between the K species and the Pt species.

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

1.

3. The CO oxidation catalyst according to claim 1, characterized in that The K species is K oxide; and the Pt species is Pt oxide.

4. A method for preparing a CO oxidation catalyst according to any one of claims 1 to 3, characterized in that the steps include: S1: K + After the solution is mixed with the composite support, it is dried and calcined; S2: mixing the product of step S1 with a Nb2O5 precursor solution, drying and calcining; S3: The product of step S3 is reacted with Pt 3+ After the solutions are mixed, they are dried and calcined.

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

10.

6. The preparation method according to claim 4, characterized in that: 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.

7. The preparation method according to claim 4, characterized in that: In step S3, the product of step S3 is reacted with Pt 3+ The mass ratio is 1:0.03~0.

08.

8. The preparation method according to any one of claims 4 to 7, characterized in that: In step S1, the K + The solution is K2CO3 solution; in step S2, the Nb2O5 precursor is Nb(NO3)5; in step S3, the Pt 3+ The solution is Pt(NO3)3 solution.

9. The preparation method according to claim 4, characterized in that: In steps S1 to S3, the calcination is all aerobic calcination, the temperature is 500 to 550° C., and the time is 2 to 3 hours.

10. Use of the CO oxidation catalyst according to any one of claims 1 to 3 in catalyzing CO oxidation reactions.

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