Catalyst for co-processing CO and escaped NH3 as well as preparation method and application of catalyst

Abstract

The invention relates to the technical field of catalytic materials, and discloses a catalyst for co-processing CO and escaping NH3 as well as a preparation method and application of the catalyst. The catalyst comprises a catalyst carrier; an exposed platinum active site and an exposed vanadium active site are loaded on the catalyst carrier, and the platinum active site and the vanadium active site are bonded through a Pt-O-V bond. According to the catalyst, N2 selectivity and CO and NH3 conversion rates can be well considered, when the catalyst is used for treating CO and escaped NH3, the risk of NOx over-standard emission can be effectively reduced, an NH3-SCO catalytic bed layer can be prevented from being additionally arranged in the middle section of an SCR and CO catalytic bed layer, and therefore the occupied area of a flue gas tail end treatment device is reduced, and the process complexity is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic materials, and in particular to a catalyst for synergistically treating CO and escaped NH3, and a preparation method and application thereof. Background Art

[0002] A large amount of NO is produced during the sintering process in steel plants. x and CO and other waste gases. NO x The production of NO is due to the reaction between N2 and O2 under high temperature. x The most effective method is the selective catalytic reduction (SCR) technology. This method uses ammonia injection to inject the reducing agent NH3 into the flue gas, which reacts with NO at a certain temperature (150-300°C). x The reaction finally generates harmless N2 and H2O. With the implementation of ultra-low emission regulations for industrial flue gas, NO x The concentration should not exceed 50 mg / m 3 In order to meet the requirements, it is used to reduce NO in actual working conditions. x The NH3 often exceeds their normal stoichiometric ratio of 1:1 to ensure that NO x On the other hand, manufacturers do not conduct sufficient computational fluid dynamics (CFD) flow field simulation when designing the SCR system. This lack of accurate simulation in engineering design may lead to excessive NH3 injection in the reactor, thereby increasing the risk of NH3 slip.

[0003] Pt-based catalyst catalytic oxidation technology is an effective means of removing CO. At the same time, catalysis of CO can release 283KJ of reaction heat per mole. The released energy is converted to the SCR reaction system that requires high-temperature reaction through a heat exchanger to achieve the purpose of saving fuel. In the exhaust gas treatment process, due to the scarcity of precious metal Pt, the CO catalyst bed will be arranged at the end of the SCR catalyst bed. This may cause the NH3 escaping from the SCR catalyst bed to react with the Pt-based catalyst to undergo an amide reaction and be converted into NO again. x , causing NO x The risk of exceeding the emission standard. The specific reaction formula is as follows: NH3+O2→-NH+-OH, -NH+O2→-HNO2, -NHO2→NO+-OH, 2NO+O→2NO2.

[0004] The selective catalytic oxidation of NH3 (NH3-SCO) to convert it into harmless N2 and H2O is a promising process for eliminating NH3 emissions. The NH3-SCO catalytic bed is installed between the SCR and CO catalytic beds. It can remove the escaped NH3 and prevent it from being converted into NO in the CO catalytic bed. x, but it will increase the floor space occupied by the flue gas terminal treatment device and the complexity of the process. In addition, the main reaction of NH3-SCO technology is that NH3 is oxidized to N2 and H2O, but the current NH3-SCO catalyst has the problem of catalytic activity and selectivity being difficult to balance. Precious metal catalysts have the characteristics of high NH3 oxidation activity and poor N2 selectivity (easy to form NO and N2O by-products), while non-precious metal catalysts have the characteristics of low NH3 oxidation activity and high N2 selectivity. Summary of the invention

[0005] In order to solve the above technical problems, that is, the method of installing an NH3-SCO catalyst bed in the middle section of the SCR and CO catalyst bed to remove the escaped NH3 will increase the floor space occupied by the flue gas terminal treatment device and the process complexity, and the NH3-SCO catalyst has the problem of difficulty in balancing the catalytic activity and selectivity, the present invention provides a catalyst for synergistically treating CO and escaped NH3, its preparation method and application. The catalyst of the present invention can better balance the N2 selectivity and the CO and NH3 conversion rate, and when used to treat CO and escaped NH3, it can effectively reduce NO x The risk of exceeding emission standards can be reduced, and the addition of an NH3-SCO catalytic bed in the middle section of the SCR and CO catalytic beds can be avoided, thereby reducing the footprint of the flue gas end treatment device and reducing the process complexity.

[0006] The specific technical scheme of the present invention is: In a first aspect, the present invention provides a catalyst for synergistically treating CO and escaped NH3, comprising a catalyst carrier; the catalyst carrier is loaded with exposed platinum active sites and exposed vanadium active sites, and the platinum active sites and the vanadium active sites are bonded by Pt-OV bonds.

[0007] The catalyst of the present invention is loaded with dual active sites of platinum (Pt) and vanadium (V), and the distance between the two active sites is relatively close. The catalytic process is as follows Figure 1 Specifically, CO and NH3 first undergo catalytic oxidation reaction on the surface of the active component Pt to produce CO2, N2, and NO. x The heat of oxidation will rapidly increase the surface temperature of the active sites, and then the newly generated NO x The continuously introduced NH3 reacts at the V site using the reaction heat to generate N2 and H2O, thereby completing the harmless conversion of CO and NH3. The reaction equations at the two active sites are as follows: 1) Reaction formula at the Pt site: 2CO+O2→2CO2; 4NH3+5O2→4NO+6H2O; 4NH3+2O2→N2O+3H2O; 2) Reaction formula at the V site: 4NO+4NH3+O2→4N2+6H2O; N2O+2NH3+O2→2N2+3H2O.

[0008] In this way, the NO generated during the Pt-catalyzed CO oxidation reaction can be removed under the coordinated action of the Pt site and the V site. x Byproducts, at the same time, the heat generated during the Pt catalytic reaction can be used to promote the reduction reaction of V species (i.e., oxidation state change), thereby increasing the rate of V catalytic oxidation of NH3. Therefore, the use of the catalyst of the present invention for harmless conversion of CO and NH3 can better balance N2 selectivity and CO and NH3 conversion rate.

[0009] In addition, industrial waste gas often contains impurity gases such as H2O and SO2, which are easy to react with the active components on the catalyst surface, resulting in a decrease in catalyst activity. Compared with other catalytic materials, the present invention uses Pt and V elements as active components. The two cooperate with each other and can maintain good catalytic stability in complex industrial waste gas. The reason is that: on the one hand, Pt can generate CO2 and NO through its efficient CO and NH3 oxidation reaction. x , and generate heat. These oxidation products help drive the reoxidation process of the V species at higher temperatures, allowing the V species to continue to remain active. On the other hand, Pt is naturally inert to SO2 and will not be oxidized by SO2 to form sulfates, thereby protecting its chemical properties. In addition, thanks to the strong acid properties of the V species, it also has good sulfur resistance.

[0010] Preferably, in the catalyst, the total mass proportion of platinum element and vanadium element is 1-5%, and the mass ratio between platinum element and vanadium element is 1:4-5.

[0011] Preferably, the platinum active site is platinum oxide; and the vanadium active site is vanadium oxide.

[0012] Preferably, the catalyst carrier is anatase TiO2.

[0013] In a second aspect, the present invention provides a method for preparing the catalyst, comprising the following steps: (1) ammonium metavanadate, oxalic acid and water are mixed, and a catalyst carrier is added, mixed, dried and calcined to obtain a primary supported product; (2) Pt 2+ The solution is mixed with the primary loading product, dried, and calcined to obtain the catalyst.

[0014] In the process of preparing the catalyst of the present invention, the method of first loading the V site and then loading the Pt site can ensure that the catalyst carrier is loaded with exposed Pt active sites and exposed V active sites, so that both active sites can contact the reactants and effectively catalyze the reaction. When the method of first loading the Pt site and then loading the V site is adopted, the Pt site is easily covered by the V species, resulting in no exposed Pt active sites in the catalyst, causing the Pt site to fail.

[0015] Preferably, in steps (1) and (2), the calcination temperature is 500-550° C. and the calcination time is 2-2.5 h.

[0016] Preferably, in step (1), the mass ratio of the ammonium metavanadate to the oxalic acid is 1:1.5-3.0, and the mass volume ratio of the catalyst carrier to water is 1 g:10-15 mL.

[0017] Preferably, in step (2), the primary loading product is reacted with Pt 2+ The mass volume ratio of the solution is 1g:0.5~3mL.

[0018] In a third aspect, the present invention provides use of the catalyst in a synergistic catalytic oxidation reaction of CO and NH3, wherein the products of the oxidation reaction of CO and NH3 are CO2, N2 and H2O.

[0019] When used to catalyze the oxidation reaction of CO and NH3, the catalyst of the present invention can reduce NO x The production of by-products can achieve higher N2 selectivity, and at the same time, the reaction heat released during the CO catalytic reaction can be used to accelerate the NH3 catalytic reaction, achieving higher CO and NH3 conversion rates.

[0020] Preferably, the temperature of the synergistic catalytic CO and NH3 oxidation reaction is 220-330°C.

[0021] In a fourth aspect, the present invention provides the use of the catalyst in treating waste gas containing NO x and CO; the application comprises the following steps: S1: Mix the exhaust gas with NH3 and use the selective catalytic reduction (SCR) method to reduce NO x Converted into N2 to obtain preliminary treated exhaust gas; S2: The preliminarily treated exhaust gas is brought into contact with the catalyst and reacted, so that CO and escaped NH3 introduced during the selective catalytic reduction process are converted into CO2 and N2 respectively.

[0022] In the SCR process, NO xDuring the SCR process, the use of excessive NH3 will introduce escaped NH3 into the treated exhaust gas. The use of the catalyst of the present invention to treat the exhaust gas after SCR can achieve the harmless conversion of this part of the escaped NH3 and the CO that cannot be removed during the SCR process. In this way, only one catalyst bed of the present invention is required at the end of the SCR catalyst bed to achieve the NO in the exhaust gas. x and CO removal, and reduce NO x To reduce the risk of exceeding emission standards, there is no need to install NH3-SCO catalytic bed in the middle section of SCR and CO catalytic bed, thus reducing the footprint of flue gas terminal treatment device, reducing process complexity and difficulty, and saving waste gas treatment costs.

[0023] Preferably, in step S2, the reaction temperature is 220-330°C.

[0024] Compared with the prior art, the present invention has the following advantages: (1) The catalyst of the present invention can achieve harmless conversion of CO and NH3, and can better balance N2 selectivity and CO and NH3 conversion rate. Therefore, it is suitable for treating NO-containing x When treating waste gas with CO, it can effectively remove CO and escaped NH3, and reduce NO x The risk of exceeding emission standards is eliminated, and there is no need to install an NH3-SCO catalytic bed in the middle section of the SCR and CO catalytic beds, which can reduce the footprint of the flue gas end treatment device and reduce process complexity.

[0025] (2) The catalyst of the present invention can prevent the active components from reacting with impurity gases (such as H2O and SO2) in industrial waste gas, and thus has good catalytic stability during use and can maintain high catalytic activity for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the catalytic process of the catalyst of the present invention.

[0027] Figure 2 The CO and NH3 conversion rates of the catalysts of Example 1 and Comparative Examples 1 and 2 at different temperatures.

[0028] Figure 3 The N2 selectivity of the catalysts of Example 1 and Comparative Examples 1 and 2 at different temperatures.

[0029] Figure 4 The CO and NH3 conversion rates of the catalyst of Comparative Example 4 at different temperatures. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the embodiments.

[0031] Overall embodiment A catalyst for synergistically treating CO and escaped NH3 comprises a catalyst carrier; the catalyst carrier is loaded with exposed platinum active sites and exposed vanadium active sites, and the platinum active sites and the vanadium active sites are bonded via Pt-OV bonds.

[0032] As a specific implementation manner, in the catalyst, the total mass proportion of platinum element and vanadium element is 1-5%, and the mass ratio between platinum element and vanadium element is 1:4-5.

[0033] As a specific implementation, the platinum active site is platinum oxide; the vanadium active site is vanadium oxide.

[0034] As a specific implementation, the catalyst carrier is anatase TiO2.

[0035] A method for preparing the above catalyst comprises the following steps: (1) ammonium metavanadate, oxalic acid and water are mixed, and a catalyst carrier is added, mixed, dried and calcined to obtain a primary supported product; (2) Pt 2+ The solution is mixed with the primary loading product, dried, and calcined to obtain the catalyst.

[0036] As a specific implementation, in steps (1) and (2), the calcination temperature is 500-550° C. and the calcination time is 2-2.5 h.

[0037] As a specific implementation, in step (1), the mass ratio of the ammonium metavanadate to the oxalic acid is 1:1.5-3.0, and the mass volume ratio of the catalyst carrier to water is 1 g:10-15 mL.

[0038] As a specific embodiment, in step (2), the primary loading product and Pt 2+ The mass volume ratio of the solution is 1g:0.5~3mL.

[0039] The catalyst is used in the synergistic catalytic oxidation reaction of CO and NH3, wherein the products of the oxidation reaction of CO and NH3 are CO2, N2 and H2O.

[0040] As a specific implementation manner, the temperature of the synergistic catalytic CO and NH3 oxidation reaction is 220-330°C.

[0041] Application of the above catalyst in the treatment of waste gas containing NO x and CO; the application comprises the following steps: S1: Mix the exhaust gas with NH3 and use the selective catalytic reduction (SCR) method to reduce NO xConverted into N2 to obtain preliminary treated exhaust gas; S2: The preliminarily treated exhaust gas is brought into contact with the catalyst and reacted, so that CO and escaped NH3 introduced during the selective catalytic reduction process are converted into CO2 and N2 respectively.

[0042] As a specific implementation, in step S2, the reaction temperature is 220-330°C. Specific embodiments 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.

[0044] 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.

[0045] Example 1: Preparation of catalyst Pt-V / TiO2 The catalyst (Pt-V / TiO2) of this embodiment was prepared by the following steps: (1) Loading vanadium oxide: Under 70℃ water bath condition, add 0.39g H2C2O4 to a beaker containing 100mL deionized water, add 0.257g NH4VO3 after dissolving, stir thoroughly until the solution turns dark green, add 9.75g anatase TiO2 powder, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put in a muffle furnace, calcine at 500℃ in air atmosphere for 2h, and obtain anatase TiO2 loaded with vanadium oxide (denoted as V / TiO2).

[0046] (2) Loading platinum oxide: Under 70℃ water bath condition, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then take 9.95g V / TiO2 powder prepared in step (1) and add it, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put into a muffle furnace, and calcine at 500℃ in air atmosphere for 2h to obtain anatase TiO2 loaded with vanadium oxide and platinum oxide (denoted as Pt-V / TiO2).

[0047] In the catalyst prepared in this embodiment, the mass proportions of platinum and vanadium are 0.5% and 2% respectively.

[0048] Example 2: Preparation of catalyst Pt-V / TiO2 The catalyst (Pt-V / TiO2) of this embodiment was prepared by the following steps: (1) Loading vanadium oxide: Under 70℃ water bath condition, add 0.20g H2C2O4 to a beaker containing 100mL deionized water, add 0.128g NH4VO3 after dissolving, stir thoroughly until the solution turns dark green, add 9.87g anatase TiO2 powder, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put in a muffle furnace, calcine at 500℃ in air atmosphere for 2h, and obtain anatase TiO2 loaded with vanadium oxide (denoted as V / TiO2).

[0049] (2) Loading platinum oxide: Under 70℃ water bath condition, add 5.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then take 9.95g V / TiO2 powder prepared in step (1) and add it, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put into a muffle furnace, and calcine at 500℃ in air atmosphere for 2h to obtain anatase TiO2 loaded with vanadium oxide and platinum oxide (denoted as Pt-V / TiO2).

[0050] In the catalyst prepared in this embodiment, the mass proportions of platinum and vanadium are 0.2% and 1% respectively.

[0051] Example 3: Preparation of catalyst Pt-V / TiO2 The catalyst (Pt-V / TiO2) of this embodiment was prepared by the following steps: (1) Loading vanadium oxide: Under 70℃ water bath condition, add 0.78g H2C2O4 to a beaker containing 100mL deionized water, add 0.51g NH4VO3 after dissolving, stir thoroughly until the solution turns dark green, add 9.5g anatase TiO2 powder, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put in a muffle furnace, calcine at 500℃ in air atmosphere for 2h, and obtain anatase TiO2 loaded with vanadium oxide (denoted as V / TiO2).

[0052] (2) Loading platinum oxide: Under 70℃ water bath condition, add 26.8mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then take 9.95g V / TiO2 powder prepared in step (1) and add it, stir until viscous. Place it in a 100℃ oven overnight to remove excess water, then grind it into powder, put it in a muffle furnace, and calcine it at 500℃ in air atmosphere for 2h to obtain anatase TiO2 loaded with vanadium oxide and platinum oxide (denoted as Pt-V / TiO2).

[0053] In the catalyst prepared in this embodiment, the mass proportions of platinum and vanadium are 1% and 4% respectively.

[0054] Comparative Example 1: Preparation of Catalyst Pt / TiO2 The catalyst (Pt / TiO2) of this comparative example was prepared by the following steps: Under 70℃ water bath conditions, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then take 9.95g of anatase TiO2 powder and stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put into a muffle furnace, and calcine at 500℃ in air atmosphere for 2h to obtain anatase TiO2 loaded with platinum oxide (denoted as Pt / TiO2).

[0055] Comparative Example 2: Preparation of Catalyst V / TiO2 The catalyst (V / TiO2) of this comparative example was prepared by the following steps: Under 70℃ water bath condition, add 0.39g H2C2O4 to a beaker containing 100mL deionized water, add 0.257g NH4VO3 after dissolving, stir thoroughly until the solution turns dark green, add 9.75g anatase TiO2 powder, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put in a muffle furnace, calcine at 500℃ in air atmosphere for 2h, and obtain anatase TiO2 loaded with vanadium oxide (denoted as V / TiO2).

[0056] Comparative Example 3: Preparation of Catalyst Pt / TiO2+V / TiO2 The catalyst (Pt / TiO2+V / TiO2) of this comparative example was prepared by the following steps: (1) Preparation of Pt / TiO2: Under 70℃ water bath conditions, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then take 9.95g of anatase TiO2 powder and stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put into a muffle furnace, and calcine at 500℃ in air atmosphere for 2h to obtain anatase TiO2 loaded with platinum oxide (denoted as Pt / TiO2).

[0057] (2) Preparation of V / TiO2: Under 70℃ water bath condition, add 0.39g H2C2O4 to a beaker containing 100mL deionized water, add 0.257g NH4VO3 after dissolving, stir thoroughly until the solution turns dark green, add 9.75g anatase TiO2 powder, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put in a muffle furnace, calcine at 500℃ in air atmosphere for 2h, and obtain anatase TiO2 loaded with vanadium oxide (denoted as V / TiO2).

[0058] (3) Mixing: Take 5.44 g of the Pt / TiO2 powder prepared in step (1) and 4.56 g of the V / TiO2 powder prepared in step (2), mix them evenly, and obtain a mixed catalyst (denoted as Pt / TiO2+V / TiO2).

[0059] Comparative Example 4: Preparation of Catalyst V-Pt / TiO2 The catalyst (V-Pt / TiO2) of this comparative example was prepared by the following steps: (1) Loading platinum oxide: Under 70℃ water bath conditions, add 13.4mL 5g / L Pt(NO3)3 solution to a beaker containing 100mL deionized water, stir evenly, then take 9.95g TiO2 powder and add it, stir until viscous. Place it in a 100℃ oven overnight to remove excess water, then grind it into powder, put it in a muffle furnace, and calcine it at 500℃ in air atmosphere for 2h to obtain anatase TiO2 loaded with platinum oxide (denoted as Pt / TiO2).

[0060] (2) Loading vanadium oxide: Under 70°C water bath conditions, add 0.39g H2C2O4 to a beaker containing 100mL deionized water, add 0.257g NH4VO3 after dissolving, stir thoroughly until the solution changes color to dark green, add 9.75g Pt / TiO2 powder prepared in step (1), and stir until viscous. Place in a 100°C oven overnight to remove excess water, then grind into powder, place in a muffle furnace, and calcine at 500°C in an air atmosphere for 2h to obtain anatase TiO2 loaded with vanadium oxide and platinum oxide (denoted as V-Pt / TiO2).

[0061] Comparative Example 5: Preparation of Catalyst Pd-V / TiO2 The catalyst (Pd-V / TiO2) of this comparative example was prepared by the following steps: (1) Loading vanadium oxide: Under 70℃ water bath condition, add 0.39g H2C2O4 to a beaker containing 100mL deionized water, add 0.257g NH4VO3 after dissolving, stir thoroughly until the solution turns dark green, add 9.75g anatase TiO2 powder, stir until viscous. Place in a 100℃ oven overnight to remove excess water, then grind into powder, put in a muffle furnace, calcine at 500℃ in air atmosphere for 2h, and obtain anatase TiO2 loaded with vanadium oxide (denoted as V / TiO2).

[0062] (2) Loading palladium oxide: Under 70℃ water bath condition, add 21.6mL 5g / L Pd(NO3)2 solution to a beaker containing 100mL deionized water, stir evenly, then take 9.95g V / TiO2 powder prepared in step (1) and add it, stir until viscous. Place it in a 100℃ oven overnight to remove excess water, then grind it into powder, put it in a muffle furnace, and calcine it at 500℃ in air atmosphere for 2h to obtain anatase TiO2 loaded with vanadium oxide and palladium oxide (denoted as Pd-V / TiO2) Test Example 1: Catalytic efficiency and selectivity test The catalysts prepared in the embodiments and comparative examples were used to catalyze the reaction of the mixed gas of CO and NH3. The flue gas conditions were as follows (the contents of the following components are all volume fractions): CO 0.8%, O2 16%, NH3 100ppm, N2 as the balance gas, and the air velocity was 30000h -1 .

[0063] The CO and NH3 conversion rates and N2 selectivity at different temperatures were measured using the catalysts of Example 1 and Comparative Examples 1 and 2. Figure 2 and Figure 3 ; Using the catalyst of Comparative Example 4, the CO and NH3 conversion rates at different temperatures were measured. Figure 4 The conversion rates and selectivities measured using the catalysts of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1.

[0064] Table 1 Catalytic efficiency and selectivity test results of catalysts Analyzing the data in Table 1, we can see that: (1) Examples 1 to 3 have high CO conversion, NH3 conversion and N2 selectivity. This shows that the use of the catalyst of the present invention can achieve harmless conversion of CO and NH3, and can better balance N2 selectivity and CO and NH3 conversion. Due to these characteristics, when the catalyst of the present invention is used to treat NO x When treating waste gas with CO, it can effectively remove CO and escaped NH3, and reduce NO x The risk of exceeding emission standards is eliminated, and there is no need to install an NH3-SCO catalytic bed in the middle section of the SCR and CO catalytic beds, which can reduce the footprint of the flue gas end treatment device and reduce process complexity.

[0065] (2) Compared with Comparative Example 1, Example 1 has significantly higher N2 selectivity. This is because: the catalyst of Comparative Example 1 has only Pt active sites, at which side reactions are likely to occur to generate nitrogen oxides (4NH3+5O2→4NO+6H2O; 4NH3+2O2→N2O+3H2O), resulting in low N2 selectivity; Example 1 uses Pt active sites in combination with V active sites, and the nitrogen oxides generated at the Pt active sites can be converted into nitrogen (4NO+4NH3+O2→4N2+6H2O; N2O+2NH3+O2→2N2+3H2O) under the catalysis of the V active sites, thereby effectively improving N2 selectivity.

[0066] (3) Compared with Comparative Example 2, the CO and NH3 conversion rates of Example 1 are greatly improved. This is because: the catalyst of Comparative Example 2 has only V active sites, which cannot catalyze CO oxidation, and has low activity in catalyzing NH3 conversion; Example 1 uses Pt active sites in combination with V active sites, can utilize Pt active sites to catalyze CO oxidation, and can utilize the reaction heat generated by Pt active sites to promote the reaction at V active sites.

[0067] (4) Compared with Comparative Example 3, Example 1 has higher CO and NH3 conversion rates and higher N2 selectivity. This is because: in Comparative Example 3, the Pt active site and the V active site are not present in the same catalyst, the nitrogen oxides generated on the Pt active site are difficult to be fully converted into nitrogen by the V active site, and the reaction heat released on the Pt active site cannot be well transferred to the V active site; while Example 1 sets both the Pt active site and the V active site in the catalyst, which can make the two cooperate better, promote the conversion of CO and NH3, and timely convert the nitrogen oxides generated on the Pt site into nitrogen.

[0068] (5) Compared with Comparative Example 4, Example 1 has higher CO and NH3 conversion rates. This is because: in Comparative Example 4, the loading order of Pt sites and V sites was swapped, with Pt sites loaded first and V sites loaded second. In this order, Pt sites are easily covered by V species, resulting in no exposed Pt active sites in the catalyst, leading to failure of Pt sites; while in Example 1, V sites are loaded first and then Pt sites, which ensures that exposed Pt active sites and exposed V active sites are loaded on the catalyst carrier, so that both active sites can contact the reactants and effectively catalyze the reaction.

[0069] Test Example 2: Catalytic stability test The catalysts prepared in Examples 1 to 3 and Comparative Example 5 were used to catalyze the reaction of a mixed gas of CO and NH3, and their catalytic stability in the presence of SO2 and H2O was tested. The flue gas conditions were as follows (the contents of the following components are all volume fractions): CO 0.8%, O2 16%, NH3 100ppm, SO2 50ppm, H2O 15%, N2 as the balance gas, and an air velocity of 30000h -1 , the temperature was 220°C. After the initial use and after 2 hours of continuous use, the CO and NH3 conversion rates were measured respectively, and the conversion rate decrease rate after 2 hours of continuous use was calculated. The results are shown in Table 2. The conversion rate decrease rate after 2 hours of use was calculated according to the following formula: decrease rate = (initial conversion rate - conversion rate after 2 hours) / initial conversion rate × 100%.

[0070] Table 2 Catalyst stability test results Analyzing the data in Table 2, we can see that: After the catalysts of Examples 1 to 3 were used continuously for 2 hours, the CO and NH3 conversion rates decreased slightly; compared with Example 1, Comparative Example 5 replaced the Pt active site with a Pd active site, and the CO and NH3 conversion rates decreased significantly after 2 hours of use. This shows that the use of two specific metal active sites (Pt site and V site) in the catalyst of the present invention can give the catalyst better catalytic stability, so that it can still maintain a high catalytic efficiency after long-term use. This is because: on the one hand, Pt can generate CO2 and NO through its efficient CO and NH3 oxidation reaction. x , and generate heat. These oxidation products help drive the reoxidation process of V species at higher temperatures, allowing V species to continue to remain active; on the other hand, Pt is naturally inert to SO2 and will not be oxidized by SO2 to form sulfates, thus protecting its chemical properties.

[0071] 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 catalyst for synergistically treating CO and escaped NH3, characterized in that: It comprises a catalyst carrier; the catalyst carrier is loaded with exposed platinum active sites and exposed vanadium active sites, and the platinum active sites and the vanadium active sites are bonded via Pt-OV bonds.

2. The catalyst according to claim 1, characterized in that In the catalyst, the total mass of platinum and vanadium accounts for 1-5%, and the mass ratio between platinum and vanadium is 1:4-5.

3. The catalyst according to claim 1 or 2, characterized in that The platinum active site is platinum oxide; the vanadium active site is vanadium oxide.

4. The catalyst according to claim 1, characterized in that The catalyst carrier is anatase TiO2.

5. A method for preparing the catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) ammonium metavanadate, oxalic acid and water are mixed, and a catalyst carrier is added, mixed, dried and calcined to obtain a primary loading product; (2) Pt 2+ The solution is mixed with the primary loading product, dried, and calcined to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that: In steps (1) and (2), the calcination temperature is 500-550° C. and the calcination time is 2-2.5 h.

7. The preparation method according to claim 5, characterized in that: In step (1), the mass ratio of the ammonium metavanadate to the oxalic acid is 1:1.5-3.0, and the mass volume ratio of the catalyst carrier to water is 1 g:10-15 mL.

8. The preparation method according to claim 5, characterized in that: In step (2), the primary loading product and Pt 2+ The mass volume ratio of the solution is 1g:0.5~3mL.

9. Use of the catalyst according to any one of claims 1 to 4 in the synergistic catalytic oxidation reaction of CO and NH3, characterized in that: The products of the oxidation reaction of CO and NH3 are CO2, N2 and H2O.

10. Use of the catalyst according to any one of claims 1 to 4 in waste gas treatment, characterized in that: The exhaust gas contains NO x and CO; the application comprises the following steps: S1: Mix the exhaust gas with NH3 and use the selective catalytic reduction method to reduce NO x Converted into N2 to obtain preliminary treated exhaust gas; S2: The preliminarily treated exhaust gas is brought into contact with the catalyst and reacted, so that CO and escaped NH3 introduced during the selective catalytic reduction process are converted into CO2 and N2 respectively.

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